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HERC2 coordinates ubiquitin-dependent assembly of DNA repair factors on damaged chromosomes.

Nature cell biology | Jan 22, 2010

Regulatory ubiquitylation is emerging as an important mechanism to protect genome integrity in cells exposed to DNA damage. However, the spectrum of known ubiquitin regulators of the DNA damage response (DDR) is limited and their functional interplay is poorly understood. Here, we identify HERC2 as a factor that regulates ubiquitin-dependent retention of repair proteins on damaged chromosomes. In response to ionising radiation (IR), HERC2 forms a complex with RNF8, a ubiquitin ligase involved in the DDR. The HERC2-RNF8 interaction requires IR-inducible phosphorylation of HERC2 at Thr 4827, which in turn binds to the forkhead-associated (FHA) domain of RNF8. Mechanistically, we provide evidence that HERC2 facilitates assembly of the ubiquitin-conjugating enzyme Ubc13 with RNF8, thereby promoting DNA damage-induced formation of Lys 63-linked ubiquitin chains. We also show that HERC2 interacts with, and maintains the levels of, RNF168, another ubiquitin ligase operating downstream of RNF8 (Refs 7, 8). Consequently, knockdown of HERC2 abrogates ubiquitin-dependent retention of repair factors such as 53BP1, RAP80 and BRCA1. Together with the increased radiosensitivity of HERC2-depleted cells, these results uncover a regulatory layer in the orchestration of protein interactions on damaged chromosomes and they underscore the role of ubiquitin-mediated signalling in genome maintenance.

Pubmed ID: 20023648 RIS Download

Mesh terms: BRCA1 Protein | Bone Neoplasms | Carrier Proteins | Cells, Cultured | Chromosomes, Human | DNA Damage | DNA Repair | DNA-Binding Proteins | Guanine Nucleotide Exchange Factors | Humans | Intracellular Signaling Peptides and Proteins | Kidney | Lysine | Mutation | Nuclear Proteins | Osteosarcoma | Phosphorylation | RNA, Small Interfering | Ubiquitin | Ubiquitin-Protein Ligases | Ubiquitination | Ultraviolet Rays

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Cold Salad-Style Udon Noodles with Tomatoes and Shiso Leaves

Cold Salad-Style Udon Noodles with Tomatoes and Shiso Leaves

This is a recipe for refreshing and delicious cold salad-style udon noodles. The fresh shiso leaves, the sour-sweet tomatoes, and the rich-flavor and crunchiness of the fried onions are addictive.

Ingredients: 1 serving

Frozen udon noodles
1 packet
Shiso leaves
5 leaves
Fried onions
1 tablespoon
2 x concentrate mentsuyu (use as is)
2 tablespoons

1. Prepare the udon noodles as directed on the package. I used microwavable noodles this time.
2. Place the noodles in a colander and rinse under running water to cool. Cut the tomatoes into 1 cm cubes. Remove the shiso leaf stems, and cut them in half lengthwise. Pile and roll them up and cut them into thin strips.
3. Drain the udon noodles, transfer onto a serving plate, top them with fried onions and tomatoes in that order, swirl in the mentsuyu, add the shiso leaves on top and it is done.
4. Here are the udon noodles that I used this time. This can be cooked in a microwave instead of boiling, so it's especially perfect for a hot summer day!

Story Behind this Recipe

I was introduced to these delicious udon noodles that I can microwave instead of boiling, so I made a delicious and refreshing dish that is easy to make even on a hot summer day.


MUSCLE, MUltiple Sequence Comparison by Log-Expectation, is a program for creating multiple alignments of amino acid or nucleotide sequences.  MUSCLE is claimed to achieve both better average accuracy and better speed than ClustalW2 or T-Coffee, depending on the chosen options.

To run this software interactively in a Linux environment run the commands:

module load muscle
muscle -in <seqs.fa> -out <alignedseqs.fa>

For documentation, refer to MUSCLE Homepage.

Additional Information

Support level:
Software category:


Ujjwal Neogi

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BACKGROUND Short term efficacy of combination antiretroviral therapy (cART) in resource-constrained settings is comparable to that found in western studies. However, long term data are limited. India has the third largest HIV infected population in the world but the long-term outcome of first line therapy according to the national guidelines has not been(More)
This review presents data on genetic and functional analysis of some of the HIV-1 genes derived from HIV-1 infected individuals from north India (Delhi, Punjab and Chandigarh). We found evidence of novel B/C recombinants in HIV-1 LTR region showing relatedness to China/Myanmar with 3 copies of Nfκb sites; B/C/D mosaic genomes for HIV-1 Vpr and novel B/C(More)
BACKGROUND HIV-1 subtype B (HIV-1B) still dominates in resource-rich countries but increased migration contributes to changes in the global subtype distribution. Also, spread of non-B subtypes within such countries occurs. The trend of the subtype distribution from the beginning of the epidemic in the country has earlier not been reported in detail. Thus(More)
BACKGROUND High plasma viremia in HIV-1 infection is associated with rapid CD4 cell decline and faster disease progression. Children with HIV infection have high viral loads, particularly in early childhood. In this study we sought to understand the relationship between duration of HIV-1 infection and viral dynamics among perinatally-infected children and(More)
INTRODUCTION Human APOBEC3G/F (hA3G/F) restricts retroviral replication through G-to-A hypermutations, which can generate drug-resistant progenies in vitro. The clinical relevance is still inconclusive. To bridge this gap, we aim to study the role of these hypermutations in evolution of drug resistance; we characterised hA3G/F-mediated hypermutations in the(More)
HIV-1 Rev protein regulates the expression of HIV-1 transcripts by binding to a highly structured stem loop structure called the Rev Responsive Element (RRE) present in the genomic and partially spliced RNAs. Genetic variation in this structure is likely to affect binding of Rev protein and ultimately overall gene expression and replication. We(More)
HIV-1 epidemic in India is largely driven by subtype C but other subtypes or recombinants have also been reported from several states of India. This is mainly due to the co-circulation of other genetic subtypes that potentially can recombine to generate recombinant/mosaic genomes. In this study, we report detail genetic characterization of HIV-1 envelope(More)


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Winchip PC3-10666 DDR3 1333MHz 64A0TRHN8G17E E-mail
Reviews - Featured Reviews: Memory
Written by Olin Coles
Friday, 07 December 2007
Table of Contents: Page Index
Winchip PC3-10666 DDR3 1333MHz 64A0TRHN8G17E
Closer Look: Winchip PC3-10666
DDR3 Comparison Review Progress
DDR3 RAM Testing Methodology
Test Results: 64A0TRHN8G17E
Final Thoughts and Conclusion

Test Results: 64A0TRHN8G17E DDR3

Testing RAM is a subject which requires a bit of technical knowledge. I have recently found a few other sites using nothing except video games to benchmark the RAM product they are reviewing, and this whole practice made no sense at all to me. Video games are GPU and CPU dependant, and RAM has a very small impact on framerate performance - as I will prove to you in my own tests. So keeping all of this in mind, I use the tools that belong in a system memory review; I use system memory tests for my benchmarks. Additionally, I don't spend three (usually tiny) pages discussing how I overclocked or how I made it to tighter timings. Every memory module comes with its very own limit, so one size doesn't fit all and this kit may not be the same as the next.

As it turned out, the Winchip PC3-10666 64A0TRHN8G17E DDR3 1333MHz 2x1GB 1.65V RAM kit could overclock to only 1381MHz from the default 1333MHz without adding any additional voltage and keeping the default clock latency values of 8-8-8-15. Keep in mind that the default memory voltage is only 1.65V, which means that there is still a good amount of room for safe voltage increases, but I'm rather skeptical of the possibilities based on this very minimal natural overclock.

Our first results were recorded from Lavalys EVEREST using the Cache and Memory Benchmark tool. The results shown below represent the average measurement obtained from the Winchip PC3-10666 64A0TRHN8G17E DDR3 kit at the 1:1 RAM-to-CPU multiplier of 1333MHz and the front side bus set to 333MHz to produce 1333MHz. After testing the default speed, I then test at the 1333 SPD-set baseline and then the overclocked speed of 1381MHz with a 345MHz FSB. The results for the average read, write, and copy bandwidth from EVEREST are displayed below.

Lavalys EVEREST.png

Everest is among my most trusted benchmark programs, and the Cache and Benchmark tool is one of the more reliable in terms of consistent results. The chart above shows that while the difference between 1066MHz and 1333MHz are noticeable, the extra 48MHz over the stock 1333MHz speed amounted to nealy no measurable increase in added bandwidth; the most notable improvement is over the 1333MHz baseline where the read bandwidth improved by nearly 3%.

With both CPU-Z and EVEREST reporting memory clocks at 8-8-8-15, I will believe that the ASUS P5K3 BIOS settings were configured correctly.

Next up was the PassMark Performance Test benchmark which runs several different system memory tests in a row. Although some of the tests are specific to the performance of the RAM, others take the CPU clock speed and front side bus into account when developing a score. Most important are the memory read and write tests, and the score based tests are bias towards CPU speed and other hardware factors.

Passmark Performance Test.png

Passmark's Performance Test offers the most consistent memory test results of the entire group, with each of the test runs resulting in a score nearly identical to the previous test run. Ideally, all of these programs should be this consistent, but until they are I would consider Performance Test to be the best tool available for testing system memory bandwidth.

SiSoft Sandra Lite.png

SiSoftware Sandra Lite XIIc offered identical results nearly the same in regards to increased performance; according to the chart above. Although the bandwidth tests are of a different nature, the improvement of 1381MHz over 1333MHz still resulted in nearly 2-3% in both the integer bandwidth and float buffered tests.

The last of our memory testing applications to run is RightMark Memory Analyzer. This program may not offer the same level of consistent test results that Performance Test does, but instead it offers a more technical approach to testing the system memory. Plus, this is a Benchmark Reviews favorite - because it's free.

RightMark Memory Analyzer.png

RightMark Memory Analyzer offer nearly the same tests that EVEREST and Performance Test have, and could be considered a bit redundant, but then again this is a technology article and us geeks like our redundancy. While it's true that Memory Analyzer hasn't been updated in over a year and seems out of development, it's still not a bad tool since it gives the second most consistent results every single run (unlike Sandra). It also offers an average "real" RAM read and write bandwidth result which most enthusiasts don't appreciate because it combines the results of dozens of tests. This is the layman's alternative to the Sciencemark v2.0 test suite, which is also gone but not forgotten.

World in Conflict.jpg

Finally, I tested with the memory multiplier set at 1:1 for 1333MHz against the overclocked 1381MHz setting in the game World in Conflict. Realizing that games can be either CPU or GPU bound, this made it difficult for me to compare all of the memory sets since the clock speed of the processor would change as I adjust the front side bus for the desired RAM speed. In the end a 48MHz system memory improvement over the 1333MHz SPD setting gave the framerate in World in Conflict only 1 FPS more in the minimum and average framerate. This mediocre improvement is evidence of how insignificant the system memory speed is in relation to video game performance.

But don't misunderstand me, because system memory could have a much larger impact on game performance if you use it to overclock the processor. This means that faster RAM allows for a faster CPU, and in turn produces a faster framerate. But in the world of system memory benchmarks, comparing the different sets of RAM in a game is pointless.

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Information Society Essays

INTRODUCTION HISTORY OF INFORMATION SOCIETY The collocation “information society” as it is now used first emerged in Japanese social science(s) in the early 1960’s. The Japanese version of the expression (joho shakai, johoka shakai) was born during a conversation in 1961 between Kisho Kurokawa, the famous architect, and Tudao Umesao, the renowned historian and anthropologist. It debuted in written texts as the title of a study published in January 1964. The author was the aforementioned Jiro Kamishima but the title was given to the study by the editor Michiko Igarashi (Sociology in Information Societies).
Three authors are in competition to win the imaginary award for being the first to use the collocation “information society” in their book’s title and due to the reconstruction difficulties in regard to the dates of preparation and publication of the manuscripts, it is almost impossible to decide which publication was the first: Yujiro Hayashi’s bestseller of 1969 (Johoka Shakai: Hado No Shakai Kara Sofuto no Shakai e, The Information Society: From Hard to Soft Society) or the introductory and popularising books by Yoneji Masuda and Konichi Kohyma published in 1968 (Joho Shakai Nyumon – Introduction to an Information Society).
However, there is no doubt at all that the birth and fast consolidation of the concept is linked inexorably to the island country: as early as 1971 a systematising “dictionary” on information society was published in Japan (Johoka Shakai Jiten, Dictionary of Information Societies). The first English language reference dates from 1970 and can also be linked to Yoneji Masuda, who used the expression in his lecture at a conference (it Information Society – what is it exactly? (The meaning, history and conceptual framework of an expression) appeared in print in the same year).
Of course all of this does not imply that the literature (in English) of the information society does not have even earlier antecedents. It was just that different expressions were used for the newly emerged social-economic entity, namely post-industrial society and white collar revolution. A common characteristic of these proto-concepts is that they isolated one of the components, i. e. one part, ofthe rapidly changing economic-social complex and suggested that it was sufficient to describe –in both a descriptive and metaphorical sense – the whole.
As a result of this, several dozen terms, each with a different approach, proliferated between 1950 and 1980 and then – in our opinion around 1980 – they merged into a comprehensive, joint umbrella term combining the concept of information and society: this new concept included and encapsulated all the previous partial concepts and even preserved the expressive power, approach and attitude they represented. The expression “post-industrial society ” was coined in 1914 in Great Britain by Ananda K.
Coomaraswamy and Arthur J. Penty, and later revived from 1958 in America (primarily by Daniel Bell) and from the end of the 1960s in French social sciences (likewise by Alan Touraine). At the beginning observers used it in a strongly normative (what should it be like? ) or strongly predictive (what will it be like? ) sense, but a shared presupposition of the authors was the accelerating “decomposition” and transformation of those industrial structures that had developed over a period of some two hundred years.
Another aspect of the same structural changes was analyzed by the Australian economist Colin Clark, who introduced the concept “the third (tertiary) sector” in 1940, drawing attention to the growing importance of services as opposed to material production (service economy=tertiary sector). In regard to technology, which forms the basis of production, the term “automation” (later “cybernation”), introduced by the automotive engineer of the Ford company D.
S. Harder in 1946, facilitated the discussions for decades, and dozens of evocative terms were originated to designate the sweeping changes generated by the hurtling development of information technology, Of these the most well-known were the various manifestations of the computer and the scientific-technological revolution. The term “brain work” replaced “manual work” and opened the way towards the concept of information society.
This was identified by the economist Alfred Marshall and the social philosopher and revolutionary Peter Kropotkin at about the same time, around 1890. For a while the word “intelligentsia” (“intelligence”), which spread in German-speaking areas after 1848 and in Russian-speaking areas after 1860, seemed to be a lucky choice to express the growing importance of those social groups in the labour market that emerged who were using their intellectual performance and knowledge to make a living.
However, because of the increasing ideological “interference” connected to the word, the term “white-collar work” spread more widely in the 1950s and it also became an “official” term used to denote a basic category in statistics and employment. At first the term, created by Upton Sinclair in 1919, was used exclusively for office workers and those officials who moved from manufacturing industry towards intellectual work; however, later it was extended to workers who carried out activities requiring certain (mainly high) qualifications.
Interestingly, it took a long time for teachers and scientists to “make it” into this category; this happened only at the beginning of the 1960s. Not long after this, the term knowledge worker was coined in 1967 by Peter Drucker. From the end of the 1960s until the beginning of the 1980s it seemed that the term “post-industrial society” would become an umbrella term used to describe the major social transformation that had taken place, but the term became more and more contradictory and vague.
On the one hand, the “traditional manufacturing industry based on manual work” was never the same as “industry”: it was Fritz Machlup, one of the pioneers of the information society discourse, who, using the language of economics, showed at the beginning of the 1960s that the production of knowledge is an economic activity and could be described with the terms used in the analysis of the industrial sector. He defined a unified knowledge industry by organizing a structure using more than 30 industries. He reviewed the conceptual field, and then described one of its sectors, the knowledge producing sector, in detail.
Finally, he pointed out that the biggest and most important sector of this industry was education. However, due to the increasingly complicated patterns of information, knowledge processes and institutes, other terms became successively unsuitable since they tried to balance the growing complexity of production by including the quaternary and quandary sectors. Neither term, “white-collar” nor “brain work” was able to reflect the process by which knowledge itself was upgraded in the case of each worker and by which traditional industries became increasingly information and knowledge intensive.
Furthermore, “post-industrialist” had the secondary meaning of “post-capitalist”, which presented a problem since the capitalist foundation had not changed in spite of the many fundamental internal realignments concerning mainly the proprietary, power, and welfare dimensions. In the end the term “information society”, which was the umbrella term used to describe the elemental social changes that took place in the second half of the 20th century, remained alone in the ring.
But not for long: the term quickly filtered through to the political sphere and the language of the media, and as a result of this it has had to face multiple challenges ever since. INFORMATION SOCIETY DEFINITION Information society is defined as a new form of social existence in which the storage, production and flow of networked information. Information society is a post-industrial society in which information technology (IT) is transforming every aspect of cultural, political, and social life and which is based on the production and distribution of information.
It is based on the production and distribution of information. It is a term used to describe the most recent stage of social history. Information society studies is an area of science that emerged in the 1990s for the systematic study of information society issues and its ‘’translation’’ into higher education curricula. Post-industrial society means the term was the most frequently used one before the expression ‘’information society gained overall acceptance.
Social informatics is a strongly interdisciplinary research field exploring the meso- and micro levels of information society and the social issues pertaining to telecommunication and computing. White collar revolution – Jean Gottmann used this expression for the title of Chapter 11 of his book Mega polis, published in 1961. By the turn of the millennium the use of the concept information society had already become widespread and was not only an everyday term in the social science vocabulary but was a term preferred by those involved in political planning, political marketing and in the world of business.
In the 20th century the most developed countries gradually entered the state of information society and it is expected that within a matter of a few decades the majority of the world’s population will be living and working in a global information society. The concept “information society” as a political and ideological construct has developed under the direction of neo-liberal globalization, whose main goal has been to accelerate the establishment of an open and “self-regulated” world market.
In fact, at the end of the century, when the majority of the developed countries had already adopted ICT infrastructure development policies, there is a spectacular peak in the share market of the communications industry CHARACTERISTICS OF INFORMATION SOCIETY Information society gives a pervasive influence of IT on home, work, and recreational aspects of the individual’s daily routine. It is a stratification into new classes those who are information-rich and those who are information-poor.
Information society also loosening of the nation state’s hold on the lives of individuals and the rise of highly sophisticated criminals who can steal identities and vast sums of money through information related (cyber) crime. FEATURES OF INFORMATION SOCIETY 1. ICT based 2. Change in communication pattern (e –mail, teleconferencing, and virtual office) 3. Information utilities (smart card, virtual education) 4. Borderless information (open sky concept) 5. Intellectual based industry (value is increase by knowledge, not labor) 6. Service industry 7. Knowledge workers . Global village 9. Network community 10. Source of power is information in the hands of many as opposed to an industrial society where the strategic source is capital. SOME RISING ISSUES REGARDING INFORMATION SOCIETY One of the greatest challenges of establishing information society is the effort to eliminate global property. The development of an information society is highly complex many of us are unprepared for the needs, challenges and opportunities presented by the information age. The ICT also gives impact to the world trade like the internet will facilitate ross-selling product. As a result, the big company will invest more money on the establishment of international trade. A growing disparity, between information rich and information poor. digital divide. Availability of basic infrastructure and ICT are the some other issues. In summary, Information society is based on these traits. First is the technology. Sophisticated IT for the production, recording, transmission and retrieval of information of all formats bringing about the high levels of interconnectedness, globalization and dependence on IT.
Secondly, extensive production of information coupled with high proportions of the labor force employed directly and directly in information activities. Third, in economy sector, information being a major commodity, being bought and sold extensively. Fourth, Operation. Integrated channels and appliances for the handling of information at large may replace specialized channels and appliances for the handling of specific forms of electronic information. Lastly, Culture. The economic and social accent on information has turned it to be a culture shrinking time and space constraints and the emergence of global virtual symbolism and realities.
CHANGES IN SOCIETY Information society began with the use of mainframe computers to access vast amounts of information. Creation, distribution and manipulation of information became the most significant economic and cultural activity in the evolving information society. While, knowledge society is creating, sharing, and using of knowledge to bring prosperity and a sense of well-being to its people. “Value added”. We also define knowledge as active and dynamic information. KNOWLEDGE SOCIETY DEFINITION Knowledge Society refers to any society where knowledge is the primary production resource instead of capital and labor.
It may also refer to the use a certain society gives to information. A Knowledge society creates shares and uses knowledge for the prosperity and well-being of its people”. CHARACTERISTIC OF KNOWLEDGE SOCIETY Knowledge societies have the characteristic that knowledge forms a major component of any human activity. Economic, social, cultural, and all other human activities become dependent on a huge volume of knowledge and information. A knowledge society is one in which knowledge becomes a major creative force.
Knowledge societies are not a new occurrence. For example, fishermen have long shared the knowledge of predicting the weather to their community and this knowledge gets added to the social capital of the community. What is new is that ?With current technologies, knowledge societies need not be constrained by geographic proximity ? Current technology offers much more possibilities for sharing, archiving and retrieving knowledge ? Knowledge has become the most important capital in the present age, and hence the success of any society lies in harnessing it.
EXAMPLES OF SOCIETIES THAT CAN BLOSSOM TO KNOWLEDGE SOCIETIES People from the same field ?Teachers teaching the same subject. ?Fans of the same musical group ?Artists with similar interests People from different fields ?Engineers talking to scientists about a scientific issue related to their engineering project ? Researchers of different fields discussing a common research problem ? Artists interested in fractals getting in touch with programmers DEFINING SCOPE OF INFORMATION AND COMMUNICATION TECHNOLOGIES (ICTS)
The driving forces of the information revolution and the ‘information society’ are the development, diffusion and use of information and communication technologies (ICTs) in contemporary societies. ICTs refer to the various technologies that enhance the creation, storage, processing, communication and dissemination of information. ICTs also refer to the different infrastructures used in these processes, their applications and the numerous services these infrastructures render. We identify the following technologies as the elements of ICTs: Media of Communication (e. . radio, television,) Information machine (e. g. Computers). Telecommunications technologies and equipment (Satellites, fiber optic cables, phones, facsimiles machines) the development in telecommunications has impacted enormously on the applications of ICTs and their uses. K- ECONOMY The K- economy refers to knowledge economy also refers to the use of knowledge technologies (such as knowledge engineering and knowledge management) to produce economic benefits is about knowledge and ability to use it and to create new knowledge value and wealth.
Wealth is measured by the results of knowledge that is inventively applied. Three things to do to prepare for K- economy are have sound knowledge about a particular discipline. Have the skills to apply that knowledge and inculcate proper values and attitudes in you. The reality of K-economy is customers are increasingly knowledgeable. The environment is complex. The ability to navigate and utilize information and learn new skills is key success factors. Values have changed and the focus should be in creating and using intellectual assets. INFORMATION PROFESSIONALS IN THE KNOWLEDGE SOCIETY
Information professionals are responsible for the capture, management and transfer of information and knowledge within and organization. Information specialist, documentation specialist, information / database manager and etc need to understand the business of their enterprise and how they should fit into overall enterprise structure. They also need to knowledgeable and flexible in adapting application of new technologies to their enterprise. THE ANALOGY OF THE GROWING PLANT OF INFORMATION SOCIETY Society grows its roots of development through the cooperative support of individuals, organizations, and tools.
Information Professionals grow as plants to be part of the Knowledge World with the same support of individuals, organizations, and tools. CONCLUSION As a result of this approach is the conceptual network that can be explained along with a general understanding of information society. With the brief history of the information society and examines the relationship between the concept and related notions such as knowledge society and K- economy. Information society is very important. Information society really gives a pervasive influence of IT on home, work, and recreational aspects of the individual’s daily routine.
It is a stratification into new classes those who are information-rich and those who are information-poor. However, knowledge society is the primary production resource instead of capital and labor. It may also refer to the use a certain society gives to information. A Knowledge society “creates shares and uses knowledge for the prosperity and well-being of its people. As a conclusion, in such a connected world, information society and knowledge society are two assets we must count on because they are key to success.

Jasmine from Graduate Way


• Open Access

Elizabeth A. Leger, Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV, USA.
Tel.: +775 784 5872; fax: +775 784 4789; e-mail: eleger@cabnr.unr.edu

Widespread invasion by Bromus tectorum (cheatgrass) in the Intermountain West has drastically altered native plant communities. We investigated whether Elymus multisetus (big squirreltail) is evolving in response to invasion and what traits contribute to increased performance. Seedlings from invaded areas exhibited significantly greater tolerance to B. tectorum competition and a greater ability to suppress B. tectorum biomass than seedlings from adjacent uninvaded areas. To identify potentially adaptive traits, we examined which phenological and phenotypic traits were correlated with seedling performance within the uninvaded area, determined their genetic variation by measuring sibling resemblance, and asked whether trait distribution had shifted in invaded areas. Increased tolerance to competition was correlated with early seedling root to shoot ratio, root fork number, and fine root length. Root forks differed among families, but none of these traits differed significantly across invasion status. Additionally, we surveyed more broadly for traits that varied between invaded and uninvaded areas. Elymus multisetus plants collected from invaded areas were smaller, allocated more biomass to roots, and produced a higher percentage of fine roots than plants from uninvaded areas. The ability of native populations to evolve in response to invasion has significant implications for the management and restoration of B. tectorum-invaded communities.

The impact of invasive species on native species, communities, and ecosystem processes has been recognized for decades (Elton 1958; Lodge 1993). Biologic invasions dramatically affect the distribution, abundance, and fitness of many native species (Williamson 1996; Mack et al. 2000). While biologic invasions are considered a significant threat to biodiversity (Sala et al. 2000; Stein et al. 2000), they do not result in the extinction of all native species impacted; many native species are able to persist alongside invaders (Hironaka and Tisdale 1963; Levine and Rees 2004; Mealor et al. 2004; Stohlgren et al. 2006). These persistent native species may possess traits (i.e. preadaptations) or sufficient phenotypic plasticity that allows for successful coexistence with invaders (MacNeil et al. 2001; Carroll et al. 2005). Preadapted traits can increase in frequency in invaded populations, or under the right circumstances, native species may evolve new mechanisms, such as chemical defenses or improved competitive ability, to cope with the invaders. Both types of rapid evolutionary responses have been documented in native populations (Schlaepfer et al. 2005; Strauss et al. 2006). Most research involving rapid evolution in native species responding to invaders has focused on native–invader interactions across trophic levels (e.g. predator–prey, host–pathogen relationships, Strauss et al. 2006). To date, there are fewer studies that address evolutionary response of native plant populations to plant invaders (e.g. Callaway et al. 2005; Lau 2006; Mealor and Hild 2007; Cipollini and Hurley 2008; Leger 2008; Ferrero-Serrano et al. 2010), but all have found evidence that some native plants can evolve in response to invasive competitors. The experiment presented here differs from previous ones in that, in addition to determining whether native populations have evolved increased ability to compete with invaders, we also identify particular traits that are evolving, as well as determine the amount of genetic variation within populations for adaptive morphological and phenological traits.

The conversion of Great Basin rangeland to Bromus tectorum L. (cheatgrass) is one of the most severe ecological degradations in the United States (Mack 1981; D’Antonio and Vitousek 1992). A combination of heavy grazing, which reduces the vigor of native perennial species, and B. tectorum invasion, which shortens fire return interval and alters nutrient cycling, has resulted in large-scale conversion of Artemisia spp. (sagebrush)-dominated plant communities to B. tectorum-dominated communities (Young et al. 1972; Evans et al. 2001; Brooks et al. 2004; Chambers et al. 2007). By 2000, nearly 12.7 million hectares of the Great Basin had been converted to B. tectorum and 45% was estimated to be at risk of conversion (Menakis et al. 2003; Bradley and Mustard 2005).

Bromus tectorum has strong negative impacts on native perennial plant fitness (Aguirre and Johnson 1991; Nasri and Doescher 1995; Rafferty and Young 2002; Humphrey and Schupp 2004). A few native grass species appear to be relatively tolerant of B. tectorum invasion, including the closely related E. multisetus M.E. Jones (big squirreltail) and Elymus elymoides Raf. (Swezey) (bottlebrush squirreltail) (Hironaka and Tisdale 1963; Booth et al. 2003; Leger 2008). Both are highly selfing, short-lived perennials that reproduce effectively from seed, persist in disturbed areas, and survive moderate fires, with gene flow occurring primarily through wind-dispersed seeds (Young and Evans 1977; Britton et al. 1990; Jones 1998; Larson et al. 2003). A tolerance for disturbance has made both squirreltail species of interest for the restoration of burned and B. tectorum-invaded areas (Jones 1998; Richards et al. 1998; Humphrey and Schupp 2002). Direct comparison between squirreltail and annual grass competitors in relative growth rate (Hironaka and Sindelar 1975; Arredondo et al. 1998), productivity under both low and high N availability (James 2008), and germination percentage and phenology (Young et al. 2003) usually favor the invader, suggesting that no individual strategy can account for squirreltail’s tolerance of invasion.

Increased ability to tolerate B. tectorum competition has been demonstrated in mature E. multisetus plants collected from B. tectorum-invaded areas (Leger 2008), but shifts in seedling performance have not been investigated. The transition from seed to seedling is the most vulnerable stage of plant life (Kitajima 2007) and is crucial for a successful restoration from seed; examination of seedling performance is an important measure for estimating fitness differences between plants. Any trait with inherited phenotypic variation that increases seedling establishment in B. tectorum-invaded areas would likely be favored by natural selection and increase in frequency over time in invaded populations. Measuring the performance of seeds from the same plant (i.e. siblings) can provide an estimate of genetic variation in particular traits. Family-level analysis has been used for decades to address the questions of inheritance and natural selection (Endler 1986; Falconer and MacKay 1996) but is not frequently applied in the context of native plant restoration.

The goals of this study are twofold: (i) to test whether seedlings of E. multisetus plants collected from invaded areas are more successful when grown with B. tectorum than seedlings from nearby uninvaded areas and (ii) to identify what growth traits may help E. multisetus seedlings to establish in B. tectorum-invaded areas. We conducted a common garden greenhouse experiment with maternal families collected from invaded and uninvaded areas with known differences in adult competitive ability (Leger 2008), and we measured E. multisetus seedling performance and B. tectorum biomass production. Two methodologies were used to identify potentially important traits. First, we identified traits that were correlated with increased tolerance of B. tectorum competition in seedlings, quantified genetic variation of these traits, and asked whether adaptive traits have shifted between uninvaded and invaded populations. If populations are evolving in response to B. tectorum pressure and if traits correlated with performance in the greenhouse are also important in the field, we would expect to see an increased frequency of inherited performance-related traits within invaded areas. Secondly, we surveyed all growth traits that varied in frequency between uninvaded and invaded populations, casting a wider net to identify additional traits that may confer a competitive advantage to native plants growing in invaded areas.

Materials and methods

Seed collection methods

Seeds of E. multisetus were collected in June 2007 from a sagebrush steppe plant community in Balls Canyon, Sierra County, California (Fig. 1.; 139840.740 N, 120803.360 W, 1600 m elevation), where a shift in invasion status occurs over a relatively small geographic area (ranging from 0%B. tectorum in uninvaded areas to 40%B. tectorum cover in invaded areas). Detailed description of community composition of the collection area is recorded in Leger (2008). At the time of seed collection, B. tectorum invasion at this site followed fence line boundaries, with B. tectorum occurring in an area that has received a longer annual season of higher intensity grazing than uninvaded areas for ∼100 years (C. Ross, personal communication). To ensure that the greatest differences between collections were disturbance history and current B. tectorum cover, rather than other abiotic conditions, all collection sites were located within 1.2 km of each other (Fig. 1). However, there are uncontrolled environmental differences between invaded and uninvaded collection sites, namely elevation and soil type. At Balls Canyon, invaded seed collection sites are, on average, 36 m lower than uninvaded areas. Higher elevation sites also exhibit different soil types than lower elevation sites; while all series are well drained and exhibit the same bedrock, the soils at higher elevation collection sites contain a higher percentage of coarse material (>2 mm) (NRCS 2008). A portion of the study area burned in 2006, and the remainder burned in 2007, and currently, the density and cover of B. tectorum in uninvaded areas sampled for this study has increased (E. Leger, personal observation), indicating that the lack of invasion in the higher elevation sites was probably due to differences in disturbance history, rather than lack of suitable environmental conditions for invasion.

Figure 1.

 Study location in Balls Canyon, Sierra County, California, with invaded and uninvaded areas in close proximity. The fence line (visible from aerial photos, but marked here for emphasis) represents a management boundary separating invaded areas (east) from uninvaded areas (west).

Seeds were collected from individual E. multisetus plants from four invaded and uninvaded sites (Fig. 1) and stored at room temperature. All seeds collected from an individual represent a maternal family line, and a ‘family’ refers to seeds collected from an individual plant in the field. Twenty-five families were randomly selected from the available pool of seeds from invaded and uninvaded sites (50 families total). Depending on seed availability, 18–20 seeds from each family were used for this experiment (991 plants total). For brevity, families and seedlings produced from seeds collected in invaded sites are subsequently referred to as ‘invaded families’ and ‘invaded plants’ and families and seedlings produced from seeds collected at uninvaded sites, ‘uninvaded families’ and ‘uninvaded plants.’ Seeds of B. tectorum were bulk-collected from the invaded portion of the study area in June 2007.

Greenhouse and data collection methods

The experiment was conducted under controlled greenhouse conditions: 4.4–26.6°C temperature range; 5–25% relative humidity; full daytime sunlight. Potting mix was locally produced (R.C. Donovan, Reno, NV) and contained bark, compost, decomposed granite, and perlite. Laboratory tests of the potting mix revealed very low mineral N (3 ppm), high alkalinity (pH = 8.0), and low estimated water holding capacity (44%) (A and L Western Agricultural Laboratories Report #08-136-060 2008). To allow for maximum rooting depth, we used pots designed for revegetation horticulture (Stuewe and Sons TPOT1; 10.2 × 10.2 × 35.6 cm; 3.2 L). Seeds received no pregermination treatment, and one individually weighed E. multisetus seed was directly sown into each pot on 26 March 2008. To create competitive conditions, we sowed five B. tectorum seeds into each of 14–16 pots for each squirreltail family (n = 791). This density was chosen to produce a competitive environment but was lower than field densities to facilitate root harvests (described elsewhere). An additional four pots per family were established as noncompeting controls (n = 200). Pots for the same family were sown together and then moved into randomly assigned positions to achieve a complete random design. We misted the soil surface immediately after sowing and continued misting twice daily for 2 weeks. For the remainder of the experiment, plants were hand-watered to saturation when the bottom third of root zone was dry (4- to 14-day intervals), which maintained relatively droughty conditions, and no supplemental fertilizer was added.

We measured or calculated a total of 47 growth traits including above-ground and below-ground measures (root methods are described in detail below): seed weight; emergence date; early growth rate (leaf number and length); root, shoot, and total biomass weight (mg) at 10, 50, and 100 days; leaf number and root to shoot ratio (R:S) at 10, 50, and 100 days; total root length (cm), root diameter (mm), number of root tips, number of root forks, and root length in five 0.1 mm size classes at 10, 50, and 100 days after peak germination. Three sequential harvests were conducted on seedlings grown in competition with B. tectorum. Harvest dates were selected to correspond to important phenological benchmarks, including seedling establishment phase (10 days after peak germination), the active growth phase (50 days), and the end of growing season (100 days). Plants for harvest were randomly selected within families. Two plants per family (n = 100) were harvested at 10 days after peak germination, (14–16 April 2008), and three plants per family (n = 150) were harvested at 50 days (16–18 May 2008). At 100 days, owing to the time requirements for root harvest, we were only able to harvest one competing and one noncompeting plant per family (n = 100, 15–18 July 2008). At 100 days, leaf number was recorded for all live plants (n = 669). Plant traits were deliberately measured at a common time, rather than at a particular age/size class, to measure E. multisetus performance relative to B. tectorum in a realistic seedling competition scenario (B. tectorum seeds typically emerge within 24–36 h of planting, which was the case in this experiment as well). Thus, differences between plants harvested on the same date may reflect patterns determined by ontology of trait development (e.g. Fransen et al. 1999; Aanderud et al. 2003) as well as fixed differences in traits.

Emergence began on 1 April 2008 and was recorded daily until last recorded emergence on 15 April 2008. By 4 April 2008, 820 of 921 seeds had emerged, which represented over 90% of all emergents, and all seedling ages are displayed from 4 April, representing the end of peak germination. For a subset of 406 seedlings, leaf length and number were measured on 23 April and 15 May 2008. Early seedling growth rate was quantified as [May leaf number−April leaf number]/May leaf number. To extract roots at harvest, we cut away pots and gently removed planting media by misting with water. Elymus multisetus were identified by leaf and root characteristics and manually separated from B. tectorum roots. Harvested roots and shoots were refrigerated (<48 h) and then digitally scanned for analysis using WinRhizo software (Regent Instruments Inc, Saint-Foy, QC). WinRhizo was utilized to quantify the following root characteristics: total root length (cm), root diameter (mm), number of root tips and root forks (measurements of root branching), and root length (cm) in five 0.1-mm-diameter size classes. Root and shoot biomass measurements were taken by drying (7 days at 60°C) and weighing root and shoot biomass separately. Total biomass was calculated as shoot + root weight. No plants produced seeds in the first year of growth, and not all families produced seeds under competition in the second year of growth, so common-garden-produced seed was collected and weighed from a subset of noncompeting control plants from each family that were maintained through July 2009.

Relative competitive performance index (CPI) was used to quantify seedling tolerance to B. tectorum competitors (Keddy et al. 1998). CPI is the percent decrease in plant performance when grown with competitors and was calculated as: [Leaf number without competition−leaf number with competition]/leaf number without competition. Leaf number is strongly correlated with plant biomass in E. multisetus (presented in results) and was used as a proxy for plant size in CPI calculation. We calculated family means for leaf number with and without competition, and these mean values were used for CPI calculation. To quantify B. tectorum suppression, above-ground biomass was collected from all pots containing B. tectorum (n = 507) at 100 days. In 32 competition pots, there was no E. multisetus emergent, but four or more B. tectorum emergents. Elymus multisetus seeds that failed to emerge were significantly smaller than seeds that did emerge (presented in results), indicating that failure of E. multisetus emergence in some pots was likely related to seed factors, rather than to soil characteristics or pot placement. Pots without E. multisetus seedlings were used to calculate mean B. tectorum weight grown alone, and B. tectorum shoots were dried and weighed in same manner as E. multisetus.

Analysis methods

Statistical analyses were performed using JMP 7.0.2 (SAS Institute, Cary, NC, USA). Analysis of variance (ANOVA) was used to compare the effects of invasion status and family on 47 growth traits of E. multisetus seedlings in competition. For seed weight, emergence date, early growth rates, 10-day harvest data, 50-day harvest data, 100-day leaf number, and next-generation seed weight, the ANOVA model included the following factors: invasion status (invaded or uninvaded); collection site (random factor, nested in status); family (random factor, nested in status and site). Family was removed from ANOVA models for the analysis of 100-day biomass and 100-day root traits, because only one plant per family was measured in each competition condition, as well as from ANOVA of CPI, because they were calculated using family means. Seed weight and emergence date comparisons included all data, rather than just competing plants, because these traits were not affected by competition condition. For B. tectorum biomass, two separate ANOVAs were conducted to analyze the effect of three levels of competition condition (grown alone, or grown with invaded/uninvaded E. multisetus) and the family of E. multisetus competitor. For this second analysis of B. tectorum biomass, E. multisetus family was nested within collection site. When analyses were significant, means were compared a posteriori using Tukey Honestly significant difference (HSD). Several growth traits were log-transformed to improve fit to assumptions of ANOVA (indicated in Table 1). Raw means and standard errors, rather than transformed values or least means square, are reported for all growth trait and competitive ability measurements. Spearman’s ρ was used to determine nonparametric correlations between family mean CPI and family means for each growth trait among uninvaded families. No adjustments were made for multiple comparisons in these analyses because the goal of these experiments was to maximize the chances of identifying potentially important traits, which can serve as the foundation for additional follow-up testing in this and other native perennial grass species.

Table 1.   Traits of Elymus multisetus grown in competition with Bromus tectorum that varied significantly by invasion status, family, or both.
Response variablenr2StatusSiteFamily
  1. Sites represent collection locations within invaded and uninvaded areas. At 100 days, root, shoot, and total weights were only measured for one plant per family, and therefore, family is not indicated as an analysis factor for these traits; this is indicated by ‘–’. Numerator degrees of freedom for the factors status, site, and family are 1, 6, and 42, respectively. Significant factors (α = 0.05) are highlighted in bold. Asterisks demark traits whose values were log-transformed for analysis.

Early traits
 Seed weight (g)9910.4469.77<0.00017.72<0.000114.14<0.0001
 Emergence date9500.090.080.77991.980.06641.860.0009
 Early growth rate (leaf no.)4020.4733.93<0.000123.17<0.00013.04<0.0001
 Early growth rate (leaf length)4020.2911.910.000610.58<0.00011.690.0065
10-day traits
 10-day total weight (mg)990.620.010.93242.380.04251.580.061
 10-day (0.201–0.3 mm)*990.690.890.34956.33<0.00011.720.0346
50-day traits
 50-day total weight (mg)1470.617.090.009110.35<0.00011.970.0033
 50-day shoot weight (mg)*1480.665.220.024516.10<0.00012.200.0007
 50-day root weight (mg)*1480.570.760.384010.04<0.00011.730.0138
 50-day R:S1470.506.400.01305.74<0.00011.390.0953
 50-day leaf no.1480.668.420.004612.45<0.00012.480.0001
 50-day root total root length (cm)*1450.530.110.73494.210.00082.020.0026
 50-day root tips*1450.502.690.10413.760.00211.690.0185
 50-day root forks*1450.561.500.22303.690.00242.350.0003
 50-day root diameter (mm)*1450.6458.21<0.00014.390.00061.550.0412
 50-day % fine roots (<0.2 mm)1450.6540.05<0.00016.46<0.00011.830.0079
 50-day (<0.1 mm)*1450.570.120.72913.320.00512.500.0001
 50-day (0.101–0.2 mm)*1450.493.910.05092.820.01441.700.0169
 50-day (0.301–0.4 mm)*1450.533.670.05846.15<0.00011.550.0398
 50-day (>0.4 mm)*1450.6437.90<0.00015.38<0.00012.020.0026
100-day traits
 100-day total weight (mg)*490.467.450.00934.800.0009
 100-day shoot weight (mg)*500.427.220.01034.110.0025
 100-day root weight (mg)*490.446.390.01544.400.0016
 100-day leaf no.*4820.5766.34<0.000139.66<0.00016.17<0.0001

At 100 days, E. multisetus plants grown in competition with B. tectorum had 81.4% less total biomass (< 0.0001, F1,100 = 46.88, r= 0.32), 70% less root biomass (< 0.0001, F1,100 = 33.15, r= 0.25), 90.2% less shoot biomass (< 0.0001, F1,101 = 51.80, r= 0.34), and 82.5% fewer leaves (< 0.0001, F1,672 = 708.12, r= 0.51) than control plants grown without competition. At 100 days, leaf number was highly correlated with total biomass (< 0.0001, F1,100 = 672.98, r= 0.87), root biomass (< 0.0001, F1,100 = 223.42, r= 0.70), and shoot biomass (< 0.0001, F1,101 = 10005.48, r= 0.91). Fifty-day leaf number was also highly correlated with 50-day total, root, and shoot biomass (all < 0.001). However, at 10 days, leaf number was not significantly correlated with any biomass measure (all > 0.05), as most plants had ≤3 leaves at this time, regardless of their size.

CPI and Bromus tectorum suppression

Competitive performance index varied significantly by invasion status (= 0.0160, F1,50 = 6.30, r= 0.31) and collection site (= 0.0496, F6,50 = 2.33, r= 0.31). Mean CPI of invaded families was significantly lower than that of uninvaded families (Fig. 2), indicating that plants from invaded areas showed a smaller decline in size when grown in competition with B. tectorum. Of the top ten B. tectorum–tolerating families, eight were from invaded areas (not shown). Bromus tectorum shoot biomass varied significantly between control plants (i.e. grown alone), those grown with invaded and uninvaded E. multisetus (< 0.0001, F2,508 = 60.55, r= 0.19, Fig. 3). Bromus tectorum shoot biomass was highest when grown with uninvaded E. multisetus, followed by B. tectorum alone, and smallest when grown with invaded E. multisetus (Fig. 3). Bromus tectorum weight also varied significantly among the E. multisetus families with which it was grown (< 0.0001, F42,476 = 5.73, r= 0.68, Fig. 4). Additionally, ranking of B. tectorum biomass by family revealed that seven of the ten families with the lowest B. tectorum biomass (i.e. most suppressive) were from invaded areas (Fig. 4).

Figure 2.

 Relative competitive performance index (CPI) of Elymus multisetus plants that differ in their exposure to Bromus tectorum in the field. Values are means ± SE. Letters represent significant differences between plants from invaded an uninvaded areas (α = 0.05). Plants with lower CPI values are better tolerators of competition, showing a smaller reduction in biomass when growth with B. tectorum.

Figure 3.

Bromus tectorum shoot biomass production when grown with Elymus multisetus seedlings that differ in invasion history. Values are means ± SE, and letters represent significant differences between groups (α = 0.05). Lower B. tectorum weight signifies a greater suppressive effect and is seen in plants collected from invaded areas.

Figure 4.

Elymus multisetus families varied significantly in their effect on Bromus tectorum weight. Values are family means ± SE. Families collected from invaded areas are labeled ‘I’ and colored white, while families from uninvaded areas are labeled ‘U’ and colored gray.

Growth traits in a competitive environment

When grown in competition with B. tectorum, E. multisetus seedlings exhibited 14 growth traits that varied significantly by invasion status and 19 growth traits that varied significantly by family (Table 1). Of the 23 growth traits that varied significantly by invasion status or family, 61 (14 traits) were found in the 50-day harvest group when we had increased statistical power because of greater sample size, while none were from the 10-day harvest group. Field-collected seeds from invaded areas exhibited significantly lower seed weights (4.32 ± 0.046 mg) than uninvaded plants (4.78 ± 0.039 mg, Table 1), and these differences persisted in seeds collected from noncompeting control plants grown in common garden (< 0.0001, F1,200 = 209.72, r= 0.91). Seeds produced in the common garden were larger than field-collected seeds, but invaded plants still produced smaller seeds (5.2 ± 0.04 mg) than uninvaded plants (6.1 ± 0.04 mg). Additionally, at each harvest date, invaded plants exhibited lower root, shoot, and total biomass, with significant differences in shoot and total biomass at 50 days and in all three measures at 100 days (Table 1; Fig. 5A–C). Invaded plants exhibited significantly lower early leaf growth rates (0.33 ± 0.013 leaves added; 0.26 ± 0.013 cm leaf length gained, Table 1) than uninvaded plants (0.45 ± 0.018 leaves added; 0.39 ± 0.035 cm leaf length gained, Table 1). Invaded plants exhibited higher R:S at 50 and 100 days, but not at 10 days; this difference was significant at 50 days (Table 1; Fig. 5D). At both 50 and 100 days, invaded plants had significantly lower leaf numbers than uninvaded plants (Tables 1 and 2). The average root diameter of invaded plants at 50 days was significantly smaller than that of uninvaded plants (Tables 1 and 2). The total length of large diameter roots (>0.4 mm) varied significantly by invasion status, with uninvaded plants exhibiting greater length of large diameter roots than invaded plants (Tables 1 and 2). Finally, at each harvest date, invaded plants exhibited higher percentages of fine roots than uninvaded plants, with significant differences at 50 days (Tables 1 and 2). Four root diameter size classes exhibited detectable family-level differences at 50 days, while only one family-level difference in root distribution was detected at 10 days (Table 1).

Figure 5.

Elymus multisetus size and allocation, for seedlings collected from invaded and uninvaded areas. Values are means ± SE at the three harvest events at 10, 50, and 100 days from peak emergence. Asterisks represent significant differences (α = 0.05) between means on a given harvest day.

Table 2.   Values for growth traits of Elymus multisetus grown in competition with Bromus tectorum by invasion status from three different harvest dates.
 10 day50 day100 day
  1. Values are untransformed means (SE). Significant differences between traits are displayed in Table 1.

Leaf number1.22 (0.06)1.20 (0.06)8.04 (0.60)6.32 (0.46)10.84 (0.36)7.81 (0.27)
Root length (cm)17.12 (0.97)16.80 (0.87)671.18 (44.97)684.01 (43.54)1067.57 (107.53)1160.37 (154.01)
Root tips49.92 (5.12)48.80 (3.88)1535.03 (130.21)1389.32 (120.84)4026.08 (467.44)3717.69 (538.23)
Root forks49.22 (3.78)51.88 (4.87)3361.81 (364.69)3926.24 (365.90)7143.76 (1022.56)8096.50 (1537.62)
Root diameter (mm)0.32 (0.01)0.31 (0.01)0.26 (0.01)0.21 (0.01)0.23 (0.01)0.21 (0.01)
% fine roots (<0.2 mm)0.34 (0.02)0.39 (0.02)0.72 (0.01)0.78 (0.01)0.74 (0.01)0.78 (0.01)
Root diameter size classes (root length in cm)
 <0.1 mm1.86 (0.22)1.68 (0.15)216.22 (20.91)237.86 (21.85)423.41 (49.67)451.23 (66.27)
 0.101–0.2 mm4.09 (0.37)4.92 (0.37)269.78 (15.24)295.20 (14.42)359.96 (28.81)451.00 (52.80)
 0.201–0.3 mm2.60 (0.19)2.49 (0.20)46.24 (3.19)49.78 (3.15)81.22 (8.42)78.60 (10.14)
 0.301–0.4 mm6.37 (0.43)5.65 (0.37)46.56 (3.62)49.34 (2.94)80.49 (8.79)80.12 (9.86)
 >0.4 mm2.15 (0.21)2.03 (0.24)90.67 (6.86)50.29 (5.62)119.38 (19.02)96.32 (19.74)

Traits correlated with CPI

Within uninvaded families, three growth traits were significantly correlated with CPI: 10-day R:S (= 0.0178), 10-day root forks (= 0.0427), and 10 day length of small diameter roots (0.101–0.200 mm, = 0.0309). Lower CPI (i.e. greater competitive ability) was correlated with higher 10-day R:S, more root forks, and greater total length of small diameter roots (Fig. 6). While 10-day root forks did not vary significantly between families when considering plants from both invaded and uninvaded areas (Table 1), among only uninvaded plants, 10-day root forks varied significantly by family (= 0.0224, F21,49 = 2.13, r= 0.70). Neither 10-day R:S nor the length of small diameter roots varied between families within uninvaded plants. Analysis of all harvested plants did not detect differences between invaded and uninvaded plants for 10-day root forks, R:S, or small diameter (0.101–0.200 mm) roots. For these three traits, power analysis revealed large sample size requirements (>1000) to detect invasion status differences.

Figure 6.

 Ten-day root traits that are significantly correlated with competitive performance index (CPI) in uninvaded families. Traits are graphed by performance rank. To produce an intuitive graph, lower numeric value of rank signifies better competitive performance (i.e. the lowest CPI value is ranked ‘1’) and the greatest R:S, root length, or number of root forks are also ranked ‘1’.

Influence of seed weight on performance

Several early growth traits were significantly affected by seed weight. Larger seeds were more likely to emerge (< 0.0001, F1,989 = 30.20, r= 0.03; nonemergent: 3.8 ± 0.1 mg; emergent: 4.6 ± 0.02 mg). Ten-day root biomass (< 0.0001, F2,99 = 28.13, r= 0.22), shoot biomass (< 0.0001, F2,100 = 26.62, r= 0.22), and total biomass (< 0.0001, F2,99 = 36.10, r= 0.27) increased with increasing seed weight. The length of roots in the three largest diameter classes root classes also increased with increasing seed weight (all < 0.02). No 50-day or 100-day growth traits were affected by seed weights (all > 0.05). Neither CPI nor B. tectorum biomass were affected by initial seed weight (> 0.05).

Evidence is emerging that biologic invasions can produce rapid evolutionary change in native plant populations (Callaway et al. 2005; Lau 2006; Mealor and Hild 2007; Cipollini and Hurley 2008; Leger 2008; Ferrero-Serrano et al. 2010). Our findings were consistent with the hypothesis that B. tectorum is exerting a strong selection pressure on native grass populations in the Great Basin: we found that E. multisetus seedlings from invaded areas were more tolerant of competition and better able to suppress B. tectorum than plants from nearby uninvaded areas. In the Great Basin, B. tectorum invasion is associated with other disturbances such as heavy grazing and fire. Therefore, trait differences observed across the invasion boundary in this study may result from additional factors that affect plant fitness, including grazing history or soil type, both of which are known to differ between invaded and uninvaded collection sites. Nonetheless, as confirmed by our results, competition with B. tectorum is known to have strong effects on the fitness of perennial native plants; wholesale invasion certainly has the ability to impose strong selection on such plants. Regardless of the number of selective agents involved, results from this type of experiment can identify plants that perform well in the presence of B. tectorum and that may offer the best potential for restoring invaded rangelands.

The ability to suppress B. tectorum biomass varied significantly by family, indicating genetic variation for this trait exists in natural populations. Although the difference in B. tectorum tolerance was small-only a 3% decrease in CPI for invaded plants, B. tectorum suppression was 30% higher for invaded plants than uninvaded plants. We do not know whether these differences are sufficient to provide a measurable advantage to E. multisetus from invaded populations when growing in a natural setting. Field testing is underway to determine whether the lower CPI and greater ability to suppress B. tectorum exhibited by invaded seedlings will result in greater survival of these plants in invaded areas.

The findings from both our correlative analysis and our examination of shifts in traits suggest that root growth plays a significant role in E. multisetus seedling performance when in competition with B. tectorum. Our most conservative approach for finding adaptive traits was a three-step process of assessing which traits were correlated with CPI within the presumed ancestral gene pool (i.e. uninvaded areas), determining the level of genetic variation in these traits, and examining whether trait values have shifted in the invaded populations. Of the 47 growth traits measured, three were correlated with CPI and all were related to root growth at 10 days. Although type I statistical errors are possible when analyses are conducted on a large number of traits, the fact that all CPI-correlated traits were identified from the earliest seedling stage suggests that these relationships are biologically important, rather than statistical artifacts. Greater tolerance to competition was associated with greater fine root production, higher R:S, and more root forking in young seedlings (Fig. 6). We did not detect a shift across invasion status for these traits, indicating either that traits have not shifted in response to B. tectorum or that we lacked the power to detect a shift. Identifying traits that are easier to measure and are reasonable proxies for root traits (e.g. resource capture) could increase sample sizes and improve the resolution of this method. Differences in root traits were also observed in our broader comparative analysis. Invaded plants produced a significantly higher percentage of fine roots and roots of smaller average diameter at 50 days (Tables 1 and 2). At 50 and 100 days, invaded plants allocated a relatively greater proportion of biomass to root production (Fig. 5).

When competition is mostly for soil resources (e.g. in situations with low soil fertility or high water stress), allocation to below-ground resource capture (measured by high R:S, high specific root length, high fine root production) improves plant performance (McGraw and Chapin 1989; Aerts et al. 1991; Tilman and Wedin 1991; Casper and Jackson 1997; Aerts and Chapin 2000). Several mechanisms have been suggested to explain the importance of fine roots in resource acquisition, including improved opportunistic nutrient foraging (Fitter 1994), adventitious root production in ephemeral nutrient patches (Drew et al. 1973; Robinson et al. 1999), and enhanced nitrogen uptake at terminal roots (Pregitzer et al. 2002). Fine root production and increased root biomass have been linked to resource capture and competitive ability in Great Basin plants (e.g. Bilbrough and Caldwell 1997; James et al. 2009). Root forks may contribute to increased competitive ability in nutrient-poor environments, where root morphology rather than physiology may confer the greatest advantage in nutrient uptake ability (Aerts 1999). For example, in an examination of genetic variation of root morphology in white clover, it was suggested that genotypes with a high number of root tips and forks will possess highly branched root systems that can explore a larger volume of soil per unit root weight, thereby improving nutrient uptake (Jahufer et al. 2008).

Both alone and in competition with B. tectorum, invaded plants were smaller than uninvaded plants. They possessed fewer leaves (Tables 1 and 2), had lower total, root, and shoot biomass (Table 1; Fig. 5), and added biomass more slowly. Nonetheless, seedlings from plants collected from B. tectorum-invaded areas were better at suppressing B. tectorum. This result is contrary to the prevailing theory that greater plant size confers greater competitive ability (Gaudet and Keddy 1988; Keddy et al. 2002). There are other plant–plant interactions besides direct competition that can result in the appearance of competitive advantage. For example, it is possible that some plants reduce the size of their neighbors releasing an allelopathic compound or stimulating the growth of soil organisms that inhibit plant growth, rather than superior resource capture (Allen and Allen 1986; Mahall and Callaway 1992). Although we did not investigate these mechanisms, they may account for our observed disassociation between biomass and competitive ability.

Beyond seeing an unexpected negative relationship between E. multisetus size and competitive ability, we observed that B. tectorum produced significantly more biomass when grown with E. multisetus from uninvaded areas than when it was grown alone, potentially indicative of a facilitative effect (Fig. 3). Interactions between plants are increasingly recognized to contain facilitative components through mechanisms such as soil aeration, root exudation (which can facilitate nutrient availability or alter biotic soil communities), or amelioration of abiotic stress (reviewed in Brooker et al. 2008). We do not know which, if any, of these mechanisms are responsible for the apparent facilitative effect of larger E. multisetus seedlings from uninvaded areas on B. tectorum, but a similar facilitative relationship has been observed in interactions between other desert annual forbs and their competitors (E. Leger, unpublished data). Results of this experiment suggest that a mechanism more complex than a positive relationship between size and competitive ability may be involved in interactions between plants in arid systems.

Our finding that smaller native plants possessed greater tolerance to B. tectorum competition than larger plants may not be that unusual; there can be adaptive value in being a small plant (Aarssen et al. 2006), especially in desert systems. Size does not always predict the impact of resource limitation: in a study of six annual species, greater biomass in isolation did not confer advantage in offspring production under competition; in fact, the most fecund species under competition exhibited relatively small biomass in isolation (Neytcheva and Aarssen 2008). Through its high seed production and soil water exploitation, B. tectorum can drastically reduce resources for native grass seedling establishment (Melgoza et al. 1990), creating highly competitive conditions where small size may be advantageous. Furthermore, in arid systems where plants are often water stressed, there can be disadvantages to greater biomass (e.g. higher transpiration and tissue maintenance costs) that result in mortality; smaller seedlings have shown a greater ability to survive drought conditions (Hendrix et al. 1991).

Invaded plants were not only smaller seedlings; they also had smaller seeds than uninvaded plants. Within a species, bigger seeds typically produce bigger seedlings, though the effect often weakens after development of the first photosynthetic tissue (e.g. Stanton 1984; Kitajima 2007). Our results were consistent with this pattern, with larger seeds producing larger seedlings for both invaded and uninvaded sources at 10 days, while initial seed weight was not significantly related to B. tectorum tolerance, B. tectorum suppression, or any 50- or 100-day growth traits, indicating that the importance of seed weight diminished over time. Nongenetic maternal provisioning can influence seed size (Roach and Wulff 1987); however, it is unlikely that larger seed size of uninvaded plants was due purely to maternal effects, as seed size differences persisted in seed collected from plants grown in a common garden, which is consistent with some degree of genetic control. Seed size is not the only growth trait that can be influenced by maternal environment, and as plants evaluated in this experiment were field collected, there are other maternal environment effects that may have affected performance which were not evaluated here. Given the large variation in family performance (Table 1, Fig. 4), even among plants that were experiencing the same maternal environment, it is likely that there was a genetic component to the differences we found between families and populations, and between invaded and uninvaded areas.

We observed family-level variation at a high frequency, which is evidence that many growth traits are inherited (Table 1). Genetic variation in fitness-related traits is the basis for natural selection, and greater genetic variation represents increased evolutionary potential and a greater likelihood of long-term population persistence (Frankel 1974; Stockwell et al. 2003). Elymus multisetus and E. elymoides are known to have a high degree of morphological variation among populations (Jones et al. 2003), relatively high amplified fragment length polymorphism (AFLP) diversity within populations compared to other perennial grass species (Larson et al. 2003), and our work demonstrates that E. multisetus also has a large amount of family-level genetic variation in growth traits. Because these grasses occur in a wide range of habitats across the Great Basin and are relatively tolerant of disturbance (Jones 1998), it is possible that the large amount of variation observed within these species is a result of their relatively large range sizes, persistence under recent disturbance, and high population densities. Populations with low genetic diversity may not possess sufficient evolutionary potential to persist under new sources of disturbance, such as climate change, land use changes, or new biologic invasions (Rice and Emery 2003; Harris et al. 2006). Although not all the inherited traits we measured were related to performance in greenhouse conditions, the level of genetic variation that we detected may improve the chances for long-term persistence of E. multisetus populations in a changing environment.

The ability of native populations to evolve in response to B. tectorum invasion has significant implications for the management and restoration of invaded communities. If long-invaded populations possess increased tolerance and competitive ability with B. tectorum (Figs 2 and 3), then seed from invaded populations could be an effective tool in restoring nearby B. tectorum-degraded areas. However, seed selection need not be limited to long-invaded populations, as there exists significant genetic variation in how seedlings respond to B. tectorum within uninvaded populations (Fig. 4). Screening plants for inherited performance-related traits and the subsequent choice of genotypes or populations that exhibit high tolerance or suppression of B. tectorum for use in restoration may improve restoration success. Additional traits may be important for survival, growth, and reproduction in B. tectorum-invaded areas, including germination timing, fire and/or grazing tolerance, and disease resistance, which also warrant investigation.

One final consideration for land managers is that restoration projects often introduce large volumes of seed into an ecosystem and may affect both the quantity and quality of local genetic variation. Commercially available seed is often derived from a single source population and sometimes even from a single genotype (Young et al. 2003; Jones and Larson 2005; Shaw et al. 2005). Because nonlocal genotypes can have a deleterious effect on the fitness of local populations (Waser et al. 2000; Montalvo and Ellstrand 2001), there is widespread concern about genetic swamping during large-scale restoration (Montalvo et al. 1997; Hufford and Mazer 2003; McKay et al. 2005). The impact of large-scale seeding on the genetic integrity of existing native populations and the ecosystem as a whole remains poorly understood (Knapp and Dyer 1998; Broadhurst et al. 2008). If B. tectorum-invaded populations are rapidly evolving novel genotypes, then the introduction of high quantities of nonlocal seed near long-invaded populations may reduce both their fitness and evolutionary potential.

The invasion of B. tectorum is converting large areas of the Great Basin from native perennial-dominated to B. tectorum-dominated plant communities; however, some native plants are able to persist in these invaded areas and may evolve in response to long-term B. tectorum presence. Our findings were consistent with the hypothesis that B. tectorum is exerting strong selective pressure on native grass populations in the Great Basin. This study provides examples of two methods for assessing potentially adaptive growth traits: (i) directly testing which traits correlate with increased performance, in either greenhouse or field settings; (ii) comparing traits of successful populations (identified by persistence in invaded areas) with plants growing in uninvaded areas. Both methods have the potential to identify important traits for persistence of native plants in invaded, disturbed, or altered environments. The ability to identify which traits are beneficial and the degree of genetic variation in these traits will help to advance our understanding of the mechanisms of contemporary evolutionary change. It can also serve a practical function by informing management and restoration of native populations in invaded or otherwise disturbed areas.

Erin Espeland, Erin Goergen, Akiko Endo, Anna Koster, Sandra Li, Phil Samuels, Kestrel Schmidt, Cassandra Woodward and Hiroaki Zamma assisted with data collection and field work. Matt Forister and Mary Peacock provided helpful suggestions on the manuscript. Jan Dawson, Chris Ross, and the California Department of Fish and Game provided historical information and access to the seed collection sites.


What Is Bulging Disc Syndrome?

Your spine is made up of a number of intervertebral discs that separate the bones of the spine (vertebrae). These intervertebral discs are made up of two layers: the inner layer is soft and pulpy and is closer to the spinal cord, and the outer layer is tough and fibrous. The outer layer is made of a strong material that allows it to function properly.

The intervertebral discs in the spine provide support, absorb shock, and help to maintain the proper shape and structure of the back. Even though the outer layer of the intervertebral disc is tough, it may wear down or break. When this happens, the inner layer pushes outwards and can protrude into the space between the vertebrae. The result of this process is known as a bulging disc.

Bulging disc syndrome is quite common and often patients have no symptoms.  However, if the inner layer protrudes close enough to a spinal nerve, a patient may report discomfort and may have debilitating symptoms. Because the bulging disc is constantly pressing against the nerve or is at least in close proximity to the nerve, patients also often experience constant pain. Most bulging discs occur in the lumbar (low back) or cervical (neck) region. Pain is often felt in these areas but may radiate into other areas of the body, including the arms and legs.

Causes Of Bulging Disc Syndrome

Oftentimes, bulging discs occur for no reason. However, they are commonly associated with increasing age and wear and tear over time. Additionally, bulging discs can occur because of improper bending and repeated poor body positioning (poor posture while sitting or standing). Normal spinal movements place relatively low pressure on the spine, whereas stressful movements (such as heaving lifting) can increase pressure on the various regions throughout the spine. This pressure can cause tearing of the outer layer of the intervertebral disc. The inner layer of the disc then bulges out towards the intervertebral space where it may compress or irritate a spinal nerve, resulting in pain. The pain can be caused by the disc’s location in relation to the nerve or by the molecules that are released by the inner layer as it bulges outward.

Intervertebral discs in the neck or lower back are most at risk for disc bulging.  When discs bulge in the neck, chronic pain may occur in the neck, head, or face. Additionally, chronic pain may also be felt in the shoulders, arms, or fingers. When discs bulge in the low back, chronic pain may occur in the lower back, pelvis, or buttocks. Additionally, chronic pain may also be felt in the legs, feet, or toes. Numbness and tingling may also occur when a bulging disc is present. Bulging disc syndrome is diagnosed by physical exam as well as by special imaging, such as magnetic resonance imaging (MRI) or disc fluoroscopy (discography).

Treatment For Bulging Disc Syndrome

Various treatments exist for bulging disc syndrome. A common and effective treatment is an epidural injection, which involves injecting an anesthetic into the space where the affected nerve is located. The injection also includes a steroid that helps to reduce the inflammation that can be caused by the bulging disc. While epidural injections are relatively conservative, the use of steroids can impair the immune system and may also lead to weight gain and diabetes in some individuals.

If there is no relief from an epidural injection, more specific treatment methods may be offered. One option is disc denervation, which involves reducing pain signals by disrupting the affected nerve. The area surrounding the disc will be numbed with medication and then a probe is inserted into the area of the nerve.  This probe delivers radiofrequency waves that help to reduce the signals from the nerve, thereby decreasing the sensation of pain.

A discectomy, also known as percutaneous disc decompression, is another surgical option that may be offered that targets the disc. This surgery involves removing the damaged and protruding disc tissue.

The Styker Dekompressor® is a tool that is used to perform this procedure. It is inserted via the skin to remove the damaged and protruding disc material without damaging the nerves. This procedure has been shown to significantly reduce pain for up to two years post-operatively. The main risks that are associated with this procedure include bleeding, infection, and nerve damage. Because this procedure involves the use of anesthetic, there are also side effects that can be caused by the anesthetic, which include chest pain, nausea, and nerve damage.

When the outer layer of an intervertebral disc breaks down, the inner layer may protrude outward resulting in bulging disc syndrome. This can cause chronic pain if the protruding disc is in close proximity to a spinal nerve. Most commonly, discs in the low back and neck region are affected resulting in chronic low back or neck pain that can also radiate to the extremities.

There are various treatment options for bulging disc syndrome that range from relatively conservative measures to more invasive procedures. The invasive procedures that are available carry more risk but they also provide more effective pain relief and are longer lasting. Speaking to your doctor will help to determine the best treatment option for your condition.

  1. Igarashi T, Kikuchi S, Shubayev V, Myers RR. 2000 Volvo Award winner in basic science studies: Exogenous tumor necrosis factor-alpha mimics nucleus pulposus-induced neuropathology. Molecular, histologic, and behavioral comparisons in rats. 2000;25(23):2975-2980.


Comparative evaluation of 3D virtual ligand screening methods: impact of the molecular alignment on enrichment

In the early stage of drug discovery programs, when the structure of a complex involving a target and a small molecule is available, structure-based virtual ligand screening methods are generally preferred. However, ligand-based strategies like shape-similarity search methods can also be applied. Shape-similarity search methods consist in exploring a pseudo-binding-site derived from the known small molecule used as a reference. Several of these methods use conformational sampling algorithms which are also shared by corresponding docking methods: for example Surflex-dock/Surflex-sim, FlexX/FlexS, ICM, and OMEGA-FRED/OMEGA-ROCS. Using 11 systems issued from the challenging “own” subsets of the Directory of Useful Decoys (DUD-own), we evaluated and compared the performance of the above-cited programs in terms of molecular alignment accuracy, enrichment in active compounds, and enrichment in different chemotypes (scaffold-hopping). Since molecular alignment is a crucial aspect of performance for the different methods, we have assessed its impact on enrichment. We have also illustrated the paradox of retrieving active compounds with good scores even if they are inaccurately positioned. Finally, we have highlighted possible positive aspects of using shape-based approaches in drug-discovery protocols when the structure of the target in complex with a small molecule is known.

David Giganti, Hélène Guillemain, Jean-Louis Spadoni, Michael Nilges, Jean-François Zagury, Matthieu Montes
June 28, 2010
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Spotlight: Mohamed Hassan bridges gap between medical system and the East African community

“I see my job as a bridge between cultures.”
University of Minnesota Health Hepatologist/Gastroenterologist Mohamed Hassan is passionate about helping members of Minnesota’s East African community navigate the healthcare system.

Understanding healthcare can be confusing. For immigrants and refugees living in the United States, the challenge is often magnified by linguistic and cultural barriers.

University of Minnesota Health Hepatologist and Gastroenterologist Mohamed Hassan, MD, born in Somalia, is doing all he can to help bridge the gap between Minnesota's large East African community and local healthcare providers. We spoke with Hassan about his own background, and his passion for helping Somalis navigate and understand the Minnesota healthcare system.

What drove you to become a doctor?
As a young boy back in Africa, I never dreamed that I would become a doctor. There just weren’t many Somali doctors in Somalia to emulate. Once I began my studies, I knew becoming a doctor would give me an opportunity to do something for the people of my country. Just as I finished my residency and fellowship, civil war broke out and I was forced to move to the United States. Although I had to give up the idea of practicing medicine in Somalia, I did not give up medicine. I moved to the Twin Cities to continue my goal after learning about the work being done at the University of Minnesota for the Somali community.

What is your role as a hepatologist / gastroenterologist?
First and foremost, hepatologists and gastroenterologists specialize in the prevention, diagnosis and treatment of disorders of the digestive tract and liver. However, a large part of my job is education. A good number of the patients I see at University of Minnesota Medical Center originated from East African countries where vaccines and preventative measures that are familiar in the US are still relatively uncommon. While it is important to diagnose and treat diseases such as hepatitis, it is equally if not more important to teach patients about how to protect themselves from contracting and spreading diseases.

Learn more about our hepatology and gastroenterology services.

Why are you passionate about community engagement?
Growing up in the Horn of Africa, I saw first-hand the effect of diseases of the digestive tract—and viral hepatitis—can have on people. Roughly 10 to 12 percent of East African test positive for Hepatitis B and between 3 and 7 percent have Hepatitis C. Both of these diseases can lead to cirrhosis and liver cancer. While many immigrants from these countries have adapted to the medical system of the U.S., there is still a lot of mistrust and misunderstanding. Often I see my job as a bridge between cultures. I’ve found that even if a competent American doctor tells them something, they still need to hear it from me to know it is sound. This is why my role so important.

How do you bridge the cultural gap?
There are many ways my colleagues and I work to ensure immigrants understand not only the U.S. health system, but how to protect themselves against diseases. We conduct numerous outreach programs in the Somali community, including the University of Minnesota Health Somali and Oromo Liver Health Fair. Liver disease is a serious problem for East African immigrants, and many don’t fully understand treatment options. There is a fear of the unknown.

Take organ donation for example. Checking “organ donor” on a driver’s license is something many Minnesotans do. This is not the case in the Somali community. Some Somalis believe that being an organ donor would set them up for medical experiments. Others believe it goes against religious beliefs. My job is to share information, answer questions and talk to them in a way they will understand—in their own language.


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March 4, 2:00 PM
Bagley Wright Theatre

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Why do some people stay sick while others become well? And where do we find the road to recovery? Lisa Kron, the multi-talented humorist, performer, playwright, and Tony Award-winning writer and lyricist behind the recent Broadway hit Fun Home, takes us on a surprising and complicated journey exploring these questions in this acclaimed comedy—which is not about her mom.

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Distance from to

Distance from Falkland Islands to Gros-Islet

Distance from Falkland Islands to Gros-Islet is 7,300 kilometers. This air travel distance is equal to 4,536 miles.

The air travel (bird fly) shortest distance between Falkland Islands and Gros-Islet is 7,300 km= 4,536 miles.

If you travel with an airplane (which has average speed of 560 miles) from Falkland Islands to Gros-Islet, It takes 8.1 hours to arrive.

Falkland Islands

59° 31´ 24.9960'' W
Altitude-22 m
CountryFalkland Islands

Falkland Islands Distances to Countries

Falkland IslandsDistance
Distance from American Samoa to Falkland Islands10,149 km
Distance from Czech Republic to Falkland Islands13,322 km
Distance from Cuba to Falkland Islands8,344 km

Gros-Islet is located in Saint Lucia.

GPS Coordinates14° 5´ 3.6960'' N
60° 56´ 43.0080'' W
Altitude61 m
CountrySaint Lucia


Pinterest • The world’s catalogue of ideas

Rama is the seventh avatar of the God Vishnu in Hinduism, and a king of Ayodhya in Hindu scriptures. Along with Krishna, the eighth avatar of Vishnu, Rama is considered to be the most important avatar of Vishnu. He is also one of the most popular gods in Hinduism and is widely worshipped throughout Nepal and India.

The road ahead for Sai devotees - Inspiration from the Mahabharata

In the Mahabharata a group of brothers, known as the Pandava brothers, are pitted against their rival cousins, the Kauravas, who divest the eldest Pandava brother of his kingdom and his wife in a fixed gambling match. Forced into exile for 13 years during which time, the brothers prepare for war with their cousins. The Pandavas prevail in an 18-day battle that causes great loss of life on both sides.

Gifted with the power of his divine father, he soared through the heavens toward the sun. Vāyu went with him, covering him with a cool breeze so that he would not be burned by the sun. The sun-god also withheld his blazing rays as he understood that Hanumān was a great servant of Viṣṇu who would later assist Him on earth.

Airavat. Indra's multi-trunked elephant from Hindu mythology, at Juna Mahal, Dungarpur. Source: Meena Kadri

Labyrinth Maze: The Chakravyuha. The Chakravyuh, or Padmavyuh, described in the "Mahabharata," is a multi-tier defensive formation that looks like a blooming lotus (padma, पद्म) or disc (chakra, चक्र) when viewed from above. The warriors at each interleaving position would be in an increasingly tough position to fight. Some people believe it was this formation that gave rise to the labyrinth.


Shan-Chyun Ku

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The p-median problem on a tree T is to find a set S of p vertices on T that minimize the sum of distances from T's vertices to S. For this problem, Tamir [14] had an O(pn 2)-time algorithm, while Gavish and Sridhar [6] had an O(nlog n)-time algorithm for the case of p=2. In this paper, we study two generalizations of the 2-median problem, which are obtained(More)
Let T = (V , E) be a free tree in which each vertex has a weight and each edge has a length. Let n = |V |. Given T and parameters k and l, a (k, l)-tree core is a subtree X of T with diameter l, having k leaves, which minimizes the sum of the weighted distances from all vertices in T to X. In this paper, two efficient algorithms are presented for finding a(More)
In this paper, we study the problem of locating a median path of limited length on a tree under the condition that some existing facilities are already located. The existing facilities may be located at any subset of vertices. Upper and lower bounds are proposed for both the discrete and continuous models. In the discrete model, a median path is not allowed(More)
including the one proposed in [5]. Minieka showed that all the eight problems can be solved in polynomial time except the one of finding the maximum distancesum tree of a specified length, which was proved to be NP-hard later in [8]. Recently, in [6,7], Peng and Lo have proposed efficient parallel algorithms on the EREW PRAM for optimally locating in a tree(More)