Transfer a song to your phone. Seems pretty fast, right? Now imagine transferring the entire printed catalog of the Library of Congress in a minute and a half. Intel says they've got the technology to make it happen (eventually). More »
The standard cheapo dorm room media center is a few cinderblocks and a few two-by-fours. But that is a pretty ugly and cliched solution. This Freefold shelving system is instead made of cardboard, and it actually looks pretty slick. More »
Family Tracker's not a new app, but this iOS4 update rescues it from near-uselessness. Thanks to the addition of multitasking, you can now track the GPS locations of family members all day, every day. Privacy invasion? Nah. That's just love. More »
One of the main criticisms of the population genetic pillar of the modern evolutionary synthesis was that too often it was a game of “beanbag genetics”. In other words population geneticists treated genes as discrete independent individual elements within a static sea. R.A. Fisher and his acolytes believed that the average effect of fluctuations of genetic background canceled out as there was no systematic bias, and could be ignored in the analysis of long term evolutionary change. Classical population genetics focused on genetic variation as abstract elementary algebras of the arc of particular alleles (or several alleles). So the whole system was constructed from a few spare atomic elements in a classic bottom-up fashion, clean inference by clean inference. Naturally this sort of abstraction did not sit well with many biologists, who were trained in the field or in the laboratory. By and large the conflict was between the theoretical evolutionists, such as R. A. Fisher and J. B. S. Haldane, and the experimental and observational biologists, such as Theodosius Dobzhansky and Ernst Mayr (see Sewall Wright and Evolutionary Biology for a record of the life and ideas of a man who arguably navigated between these two extremes in 20th century evolution because of his eclectic training). With the discovery that DNA was the specific substrate through which Mendelian genetics and evolutionary biology unfolded physically from generation to generation a third set of players, the molecular biologists, entered the fray.
The details of genetics, the abstract models of theorists, the messy instrumentalism of the naturalists, and the physical focus of the molecular researchers, all matter. Through the conflicts between geneticists, some arising from genuine deep substantive disagreement, and some from different methodological foci, the discipline can enrich our understanding of biological phenomena in all its dimensions. Genomics, which canvasses the broad swaths of the substrate of inheritance, DNA, is obviously of particular fascination to me, but we can also still learn something from old fashioned genetics which narrows in on a few genes and their particular dynamics.
A new paper in PLoS Biology, Cryptic Variation between Species and the Basis of Hybrid Performance, uses several different perspectives to explore the outcomes of crossing different species, in particular the impact on morphological and gene expression variation. You’ve likely heard of hybrid vigor, but too often in our society such terms are almost like black-boxes which magically describe processes which are beyond our comprehension (hybrid vigor and inbreeding depression freely move between scientific and folk genetic domains). This paper attempts to take a stab at peeling pack the veil and gaining a more fundamental understanding of the phenomenon. First, the author summary:
A major conundrum in biology is why hybrids between species display two opposing features. On the one hand, hybrids are often more vigorous or productive than their parents, a phenomenon called hybrid vigor or hybrid superiority. On the other hand they often show reduced vigour and fertility, known as hybrid inferiority. Various theories have been proposed to account for these two aspects of hybrid performance, yet we still lack a coherent account of how these conflicting characteristics arise. To address this issue, we looked at the role that variation in gene expression between parental species may play. By measuring this variation and its effect on phenotype, we show that expression for specific genes may be free to vary during evolution within particular bounds. Although such variation may have little phenotypic effect when each locus is considered individually, the collective effect of variation across multiple genes may become highly significant. Using arguments from theoretical population genetics we show how these effects might lead to both hybrid superiority and inferiority, providing fresh insights into the age-old problem of hybrid performance.
There are various ways one presumes that hybrid vigor could emerge. One the one hand the parental lines may be a bit too inbred and therefore have a heavier than ideal load of deleterious alleles which express recessively. Since two lineages will likely have different deleterious alleles, crossing them will result in immediate complementation and masking of the deleterious alleles in heterozygote state. Another model is that two different alleles when combined in heterozygote state have a synergistic fitness effect. We generally know of heterozygote advantage in cases where there’s balancing selection, so that one of the homozygotes is actually far less fit than the other, but the fitness of the heterozygote is superior to both homozygotes. But that is not a necessity, and presumably there could be cases where both homozygotes are of equal fitness, but the heterozygote is of marginally greater fitness.
As for hybrid inferiority, a simple model for that is that lineages have co-adapted complexes of genes which are enmeshed in gene-gene networks. These networks are finely tuned by evolution and introduction of novel alleles from alien lineages may lead in destabilization of the sensitive web of interconnections. This model taken to an extreme is a scenario whereby speciation could occur if two lineages become mutually exclusive on a particular genetic complex which is “mission critical” to biological machinery (imagine that the gene involved in spermatogenesis is effected).
These stories are fine as it goes, but they do have something of an excessively ad hoc aspect. A little light on formalization and heavy on exposition. In this paper the authors aim to fix that problem. To explore genetic interactions in hybrids, and how they effect gene expression, they selected the genus Antirrhinum as their model. These are also known as “snapdragons.” Like many plants Antirrhinum species can hybridize rather easily across species barriers. They observe the effect of taking genes from a set of species and placing them in the genetic background of another. In particular they are focusing on A. majus, hybridizing it with a variety of other Antirrhinum species, as well as introgressing alleles from the other species onto a A. majus genetic background (so an allele on a specific gene is placed within the genome of A. majus).
Just as they focus on a specific genus of organism, so they also focus on a specific set of genes and the molecular and developmental genetic phenomenon associated with those genes. The genes are CYC and RAD, which are located near each other genomically, with CYC being a cis-acting regulator of RAD. In other words, CYC modulates the expression of RAD which is on the same chromosome. Variance in gene expression simply defines the concrete difference in levels of protein product. Mutant variants of CYC and RAD, cyc and rad, are created by insertion of transposons. Insertion of transposons can abolish gene expression, resulting in removal or alteration of function. What is that function? I’m rather weak on botanical morphology, so I’m going to be cursory on this particular issue lest a reader correct me strenuously for misapplication of terminology. So I’ll show you a figure:
I added the labels. C is basically what majus should look like, while G is a totally “ventralized” mutant. B and F approach wild type, but the other outcomes are more mixed. Note the genotypes in the small print. Table 1 measures the expression levels of the gene product for the various genotype:
Look at the first row; mutant variants of CYC which are nonfunctional reduce normal copies of RAD down to 20% levels of gene expression. That’s because CYC is a transcriptional regulator of RAD. The process is not reversed. RAD lacking functionality does not impact CYC (last row). Finally, the heterozygote states does result in reduced dosage of the gene product. Though the phenotypes might be closer to wild type than the mutant, the molecular expression of the gene is substantially changed. This is one of the issues which is always important to remember: the extent of dominance exhibited by a sequence of phenotypes consequent from a particular genotype may vary dependent on which phenotype you are a highlighting. On a molecular level there is incomplete dominance. Additive effects. On the level of exterior morphology there is more perceived dominance. This is not even addressing the issue of pleiotropy, where the same gene may have dominant and recessive expression on two different traits simultaneously in inverted directions (i.e., the recessively expressed allele in trait A may be dominant in B, and vice versa).
Figure 1 shows the different allelic expression levels in hybrids of Antirrhinum species. But what about the impact of the combinations on phenotype? I’ve reedited figure 4 so it fits better on this page:
Here’s the text description for the figure:
GEM spaces for CYC and RAD, showing location of various genotypes and species.
(A) Dorsalisation index for each position in GEM space using values from Table 1. Standard errors for DIcor and expression levels are shown (if error bars are not visible, they are smaller than the symbols). A smooth surface has been fitted to the data (see Materials and Methods for details of surface fitting). Note that the wild-type, C, lies on a plateau while the double heterozygote, E, is on the slope. (B) Top view of the GEM space, incorporating the relative expression values from the species taken from Figure 1 (circles). These values were adjusted assuming that A. majus (red circle) is at position (1, 1) in gene expression space. Triangles indicate expected gene activity values in the double heterozygote (CYC = x×0.6; RAD = y×0.5; see Table 1E). Some of the double heterozygotes are predicted to have DI values above or below the position of A. majus. Triangles pointing upwards indicate species showing notch phenotype. (C) Enlargement of rectangle in (B). bra, A. braun-blanquetii; cha, A. charidemi; lat, A. latifolium; lin, A. linkianum; maj, A. majus; meo, A. meonanthum; pul, A. pulverulentum; str, A. striatum; tor, A. tortuosum; cha-BC, introgression of A. charidemi into A. majus background.
GEM = gene expression–morphology (GEM) space. As I note above the mapping between the manifestation of genetic variation on the molecular level and on the gross morphological level may be subtle. Figure 4 has the two genes under consideration forming a plane through the x and z-axes, while gross morphology is illustrated on y-axis. What’s on the y-axis is actually a principal component which serves as an abstract representation of the morphological variation of the petal structure illustrated in the earlier figure. They call it the “dorsalization index” (Di). The wild type = 1 and the expressed mutant = 0. So the interval 0 to 1 in phenotype space is a good gauge as to the deviation of the morphology from wild type.
The letters in panel A are representations of the letters in the first and second figures within this post. G represents the double homozygote mutant. It stands to reason that its Di is ~ 0. C, B, F, and to some extent E, form a “plateau” where gene expression may vary a fair amount but the morphology remains relatively stable. A, D, H and I represent intermediate cases on the “slope” where changes in genetic architecture produce large shifts in phenotype. The idea of dominance and recessiveness already indicate that not all genetic variation is created equal, and that there are non-linearities in the interaction of genetic variation and phenetic variation. Here using Di and quantitative levels of gene expression one can take the verbal/qualitative insight and translate it into a quantitative relation.
Panel B seems to be similar to L. L. Cavalli-Sforza’s synthetic maps of PC variation of gene frequencies. It’s taking the y-axis in A and transforming it into the clinal grade on the plane. The circles in panel B represent conventional hybrids between A. majus and other species within its genus. There is variation in gene expression levels within these hybrids, but note that they reside on the phenotypic plateau. In contrast, the triangles show double heterozygotes: (CYC RAD)/(cyc cyc). The heterozygote combinations are for a variety of species, as indicated in the figure text. Note that they explore more of the phenotype type space, as evident in panel C, which is just an zoom of the rectangle in panel B.
So far they’ve shown that homozygote mutants abolish the wild type morphology, while heterozygotes of various combinations move over phenotype space. RAD’s expression is contingent on CYC, so that can explain some of the unpredictability of the variation when viewed in light of a simple qualitative model. Additionally, wild type hybrids move in the gene expression dimension, but not in the phenotype space. So next they looked at the impact of a particular species CYC and RAD genes against the majus genetic background in the doubly heterozygote state. In other words we’re not talking about a hybrid where half of the total genome content is from each parental species. We’re talking about introgression of alleles at a specific locus from species A to species B, so that the nature of the total genome content is of species B, except at a particular locus or set of loci, where they are from A. Figure 5 shows the results of such a cross:
The result of these studies show that alleles from A. charidemi are much more efficacious in maintaining wild type phenotype in the heterozygote state than A majus. This is because of underlying gene expression differences across species. Observe that CYCchar is particularly relevant because of the dependence on the RAD locus upon CYC in terms of gene regulation. The presence of charidemi and majus derived alleles on the same chromosome, so that cis--acting dynamics were operative, was achieved through recombination. A further exploration of the expression of each allele individually confirmed that CYCchar had a 30% higher expression than CYCmaj.
OK, so at this point we’ve examined the general topology of GEM. The relation between morphology and gene expression, the nature of the landscapes which describe their relationship. Next, we’ll move to GEF, gene expression–fitness (GEF) spaces. Genes/gene expression, phenotypes, and fitness, are the three-legged-stool of evolution, and specifically natural selection and adaptation. In a proximate sense the relationship between genes and phenotypes are physically mediated by a sequence of developmental pathways over life history. In an ultimate, evolutionary, sense, the relationship between genes and phenotypes are mediated by fitness, with variation in phenotypes over time being driven by variation in genotypes via the engine of fitness differentials. The distinction between evolutionary and non-evolutionary genetics, the abstract/theoretical and concrete/empirical, crops up with something like epistasis. On the one hand epistasis refers to physical relationships between genes. On the other hand it can also describe the variation in trait value which emerges from the interlocus interactions. And finally, it can refer to non-linear fitness effects due to combinations of alleles across loci.
In this case we’ve already seen how variation on the molecular level of gene expression due to genetic differences at two loci do not always translate into variation in morphology. The plateau in GEM space is simply due to the invariance in the morphological dimension. Once variance shows up you see the plane tilt and become steep. GEF space is exactly analogous, except that we are looking at variation in fitness on the y-axis. This is the domain of evolution, the ultimate. This section has only one figure:
GEM was based on concrete observation and experiment. GEF space is more theoretical, insofar as from what I can tell they didn’t measure fitness in actual lineages, but rather hypothesized distributions of fitness from parameters which might give us insight into hybrid vigor and/or breakdown. Red is obviously increased fitness and blue decreased. The surface of the landscape is simply where the gene expression values intersect with realized fitness. There are several alternative topologies here. I’ll quote the figure text:
Gene expression levels for two genes are plotted along the horizontal plane while fitness is along the vertical axis. (A) Radially symmetrical peak. (B) 2-D Projection of (A) showing location of effectively neutral zone and position of two parental genotypes (P1, P2 triangles), the resulting F1 (square) and additional genotypes observed in the F2 (diamonds). The F1 in this case is nearer to the centre of the peak while the F2s have similar fitness to the parents. (C) Diagonal ridge. (D) 2-D projection of diagonal ridge showing tilted elliptical neutral zone. The F1 is nearer to the peak than the parents but some F2 genotypes may now have lower fitness and fall outside the neutral zone. (E) Curved ridge. (F) 2-D projection of curved ridge showing banana-shaped neutral zone. Some F1 genotypes may have lower fitness and fall outside the neutral zone.
First, one has to introduce the concept of ‘drift load.’ A population of a particular genotype has an expected fitness, while in the best-of-all-world’s there is an idealized fitness peak. Random genetic drift will drive the population away from the peak because variance which shifts the gene frequencies from generation to generation. The power of drift to alter gene frequencies is inversely proportional to effective population size, Ne, the proportion of the population contributing to the genes of the next generation (often a rule of thumb is 1/3 of the census size, though this probably applies for human-scale organisms; usually it is much smaller than census). The drift load is the drag on fitness induced by drift, and is defined by the equation: ~1/(4Ne). In other words, as N ? ? the drift load disappears because sample variance is eliminated. But this load is applicable at each loci, so if you sum up across many genes then small increments can produce a non-trivial fitness decrement simply due to the vicissitudes of generation-to-generation variance.
In the figure above the dark red zone is neutral. That means there’s no fitness variance. That’s the “fitness plateau” equivalent to the phenotypic plateau observed above. P1 and P2 are parental generations, different lineages. F1 are hybrids, while F2 are crosses of the hybrid generation. The deviation of P1 and P2 in all the panels from the center of the fitness plateau are indications of drift load. The shape and nature of the fitness plateau are critical in determining the outcomes for the F1 and F2 generation, and consequent vigor or breakdown. Geometrically you see the rationale for hybrid vigor in panel A and B, as F1’s are closer to the center of the fitness plateau as drift load is dampened on the cross. In the text the authors note that ‘the variance around the optimum of the mean of two independent populations is half that of either one, and so the “drift load” is half as great.’ So instead of ~1/(4Ne), you have ~1/(8Ne). This is a gain in fitness which can be substantial over many loci. Over 1,000 genes it would be a gain of 0.125, which is very large, and can explain heterosis. But as many farmers know the F2 generation often exhibits a regress in fitness. “Hybrids do not breed true.” In a Mendelian model some of the offspring of the hybrids will segregate the alleles so that homozygotes will reappear. In panel A the F2 have about the same fitness as the parental cases. In panel B this is not the case; new genotypic combinations presumably are produced which lay outside of the fitness plateau, and this leads to a major hybrid breakdown. In panel C the F1 are slightly below the parental populations in fitness, while the F2 are far below them.
In the discussion they then work back from the theoretical digression to its relevance to observed variation, and their particular model taxon:
The phenotype and fitness of species hybrids will reflect the extent to which these various GEF scenarios apply to the many thousands of genes in the genome. Radial or elliptical neutral domains, centred around a common position in GEF space, would be expected for loci that are under similar normalising selection in multiple environments. This situation likely applies to the CYC and RAD genes as all species in the Antirrhinum group have similar asymmetric closed flowers. It would also be expected for many loci controlling basic physiology and growth. F1 hybrids would therefore be expected to show higher fitness and increased performance with respect to these traits. This provides an explanation for hybrid vigour that avoids the pitfalls of previous models that require fixation of loci with major deleterious effects or that invoke special mechanisms for heterozygote advantage. A similar explanation has been proposed to account for the origin of hybrid vigour between domesticated inbred lines…Hybrid vigour is usually lost in F2s or recombinant inbred lines, indicating that many of the loci involved interact to give tilted rather than untilted neutral zones.
Although hybrid vigour is commonly observed for physiological traits, the overall fitness of species hybrids is often lower than that of the parents, with sterility or other dysgenic effects being observed. This observation may partly reflect adaptation to different environments and thus shifts in the shape of fitness surfaces that drive changes in genotype. However, it may also reflect loci that interact to give curved or L-shaped neutral zones…Such zones will be prevalent for traits that involve more complicated epistatic interactions, perhaps accounting for the dysgenic effects observed in F1s. The negative contribution of loci with curved neutral zones is likely to increase with time, as loci drift towards the extremities of the banana-shaped neutral domains.
Remembering that there is a possible association between cis-elements and physiological traits,. it is interesting to observe that one may be able to infer fitness landscapes from patterns of morphological and genetic variation. I don’t know how robust the generalizations above are, and obviously this particular paper is more about setting up a testable framework than validating that framework, but we’ve come a long way from “beanbag genetics.”
Citation: Rosas U, Barton NH, Copsey L, Barbier de Reuille P, & Coen E (2010). Cryptic Variation between Species and the Basis of Hybrid Performance. PLoS biology, 8 (7) PMID: 20652019
Image Credit: Wikimedia
Lake Ontario has some key differences compared to her equally-sized sister lake, Ontario Lacus: The Great Lake has water; Ontario Lacus has methane, ethane, and propane. The Great Lake invites sunbathers; Lacus’ beaches, almost ten times further from the sun, are icy cold. The Great Lake is located on Earth; Lacus on Saturn’s largest moon, Titan. Despite all these distinctions, new research points to an important similarity: liquid levels in both lakes change with the seasons.
From June 2005 to July 2009, the Ontario Lacus shoreline has receded by about 6 miles, Alexander G. Hayes and his coauthors report in two papers submitted to Icarus and the Journal of Geophysical Research. Looking at other lakes in Titan’s southern hemisphere, it seems they are dropping in depth by about three feet per year.
Despite its shoreline’s rapid retreat, there is little worry that Ontario Lacus and other Titan lakes will disappear forever. Scientists expect that the evaporation is just part of a cycle of evaporation and condensation, that changes with the seasons. The four years of observation, carried out by NASA’s Cassini spacecraft, represents only the period from about mid-summer to fall, since a Titan year lasts 29.5 Earth years.
The discovery that Titan’s lakes are evaporating. . . suggests that there are active weather and geological cycles on Titan analogous to those on Earth. But on Titan the liquid driving those cycles is not water but methane, explained Oded Aharonson, a planetary scientist at the California Institute of Technology.“This is a wonderful opportunity and rare in the solar system to observe a planet with working liquid on its surface, a volatile agent that is responsible for altering its geology and participating in its weather cycle by evaporating and precipitating,” Dr. Aharonson said.[New York Times]
The Synthetic Aperture Radar (SAR) on the Cassinni spacecraft provided the data to help the researchers determine the lakes’ properties and see into their depths. Hayes explains:
“[The liquid] is fairly clear to radar energy—that is, transparent, like liquid natural gas.” Because of this, radar can see through the liquid in Titan’s lakes to a depth of several meters. “Then the radar hits the floor, and bounces back,” he says. “Or, if the lake is deeper than a few meters, the radar is completely absorbed, producing a ‘black’ signature.”[California Institute of Technology]
By watching how images created from this radar data (see image right) changed over four years, the researchers witnessed the evaporation in detail.
“Cassini continues to take our breath away as it fills in the details on the surfaces of these far-off moons,” said Linda Spilker, Cassini project scientist based at JPL.[NASA/JPL]
Given all that evaporated methane, a visit to the surface might have a similar effect.
The amount of methane gas produced by the changes seen so far exceeds the methane expelled by all the cows on Earth over a year, according to the press release. Yeah, might want to rethink that vacation after all. [DiscoveryNews]
Related content:
80beats: Weird Chemistry on Titan *Could* Be a Sign of Methane-Based Life
80beats: New Take on Titan Hints at More Fuel for Potential Life
80beats: New Evidence for Ice-Spewing Volcanoes on Saturn’s Moon Titan
80beats: Hydrocarbon Lake on Saturnian Moon May Be a Hotspot for Alien Life
80beats: On Saturn’s Moon Titan, It’s Raining Methane
Image: NASA & Cassini Radar Science Team, NASA/JPL/Caltech
I feel like a castaway in a sea of glossy black plastic, chrome, and glowing blue buttons. Do we really need every piece of electronics to look the same, sandwiched in this shiny ebony that is the 21st Century beige? More »
For 99 notes, wannabe DJs can get a pair of point and looping controllers designed for use with laptops, CDJs, turntables and mixers. They glow bright red/green, look like dice (kind of) and roll dem phat beatz out. Or something. More »
Thermocuple type K installed on flare (100meter height) is not working, the reading is varying between 40 to 200 deg C instead of showing the ambient temperature,used the correct TC type extension cable and running down from element to FF transmitter for 100meter distance.
what could be th
HotHardware has a thorough review of the HP ZR30w, a 30" LCD monitor with exceptional color resolution. Their verdict? The S-IPS panel and huge color gamut make for an excellent display that's affordable among its peers. More »
Hi
I am at a power plant and we are interested in knowing the advantage of doweling the vertical CW Pump 1100 kw, 910 rpm with pump. media is sea water for cooling the turbine condensor.
Some times during running condition our alignment goes out and we get vibration.
Will
Do you know an early career scientist who has demonstrated excellence in engaging the public on scientific topics? Go nominate her or him for the AAAS Early Career Award for Public Engagement with Science:
A monetary prize of $5,000, a commemorative plaque, complimentary registration to the AAAS Annual Meeting, and reimbursement for reasonable hotel and travel expenses to attend the AAAS Annual Meeting to receive the prize are given to the recipient.For the purposes of this award, public engagement activities are defined as the individual’s active participation in efforts to engage with the public on science- and technology-related issues and promote meaningful dialogue between science and society.
The award will be given at the AAAS Annual Meeting.
Details about eligibility and the submission process here.
The remaining details of Dell Streak's release continue to trickle out. This morning we learned it would eventually run Froyo. Now we know the price: $299 with a 2 year AT&T contract or $549 unlocked. Updated More »
Washington, D.C. – The Commercial Spaceflight Federation is pleased to announce that Andrews Space, Inc., DCI Services and Consulting, MEI Technologies, Special Aerospace Services, and SRA International have joined the Federation as Associate Members. The Commercial Spaceflight Federation now includes over 30 leading aerospace companies.
Bretton Alexander, President of the Commercial Spaceflight Federation, stated, “It is very exciting to have these innovative companies joining the Commercial Spaceflight Federation. Each of them is contributing unique skills and assets to our industry, and each additional company better enables us to accomplish our mission of promoting the growth of the commercial space industry.”
The new associate members of the Commercial Spaceflight Federation made the following statements:
• Jason Andrews, CEO of Andrews Space, Inc. stated, “Andrews strongly supports the CSF’s efforts to promote and develop a robust commercial space industry within the US focused on developing and sustaining critical existing and emerging markets.” (Headquartered in Seattle, Andrews Space, Inc. was founded in 1999 to be a catalyst in the commercialization and development of space, and is an affordable integrator of aerospace systems and developer of advanced space technologies.)
• Chad Brinkley, President of DCI Services and Consulting, stated, “DCI is excited to work with like-minded entities to provide safe and cost-effective space transportation products and services to satisfy our customers’ needs.” (Based in Houston, Texas, DCI Services and Consulting is a systems engineering and integration company focused in the aerospace and defense market.)
• Jim Baker, Director, Commercial Sector, at MEI Technologies stated, “As the commercial spaceflight industry grows, we see our involvement in CSF to not only be a way of providing the critical skills necessary to support our nation’s leadership in space but also to be a part of inspiring the next generation scientists, engineers, and explorers who will maintain that leadership. As such, MEI Technologies is proud to join with our industry colleagues and CSF in advancing commercial spaceflight.” (Headquartered in Houston and founded in 1992 as Muñiz Engineering, MEI Technologies employs more than 800 individuals that serve more than 60 clients in the civil, commercial and defense industries.)
• Heather Bulk, President and CEO of Special Aerospace Services, stated, “We are truly proud to be a member of the Commercial Spaceflight Federation with its strong vision and leadership by the members. SAS looks forward to continuing our journey with those who live by our motto…’who dreams wins!’ ” (Headquartered in Boulder, Colorado, Special Aerospace Services provides experienced program support in the areas of launch vehicles, spacecraft systems, space system engineering, human rating, and space safety.)
• Brian Buckley, SRA International’s Space Systems Group Lead, stated, “Commercial Spaceflight Federation (CSF) is the perfect forum for SRA International to introduce our award-winning Spacecraft Command Language (SCL) product line for flight and ground systems. SCL has contributed to the success of many NASA and DoD missions and we look forward to sharing our software development capabilities and experience in mission critical systems with the CSF.” (Founded in 1978 and headquartered in Fairfax, Virginia, SRA International provides the expert knowledge, technical tools and solutions that governments, agencies and companies need to improve performance, reduce costs and risks, introduce enterprise efficiencies and enhance human health.)
About the Commercial Spaceflight Federation
The mission of the Commercial Spaceflight Federation (CSF) is to promote the development of commercial human spaceflight, pursue ever-higher levels of safety, and share best practices and expertise throughout the industry. The Commercial Spaceflight Federation’s member companies, which include commercial spaceflight developers, operators, spaceports, suppliers, and service providers, are creating thousands of high-tech jobs nationwide, working to preserve American leadership in aerospace through technology innovation, and inspiring young people to pursue careers in science and engineering. For more information please visit http://www.commercialspaceflight.org or contact Executive Director John Gedmark at john@commercialspaceflight.org or at 202.349.1121.
About Andrews Space, Inc.
Headquartered in Seattle, Andrews Space, Inc. was founded to be a catalyst in the commercialization and development of space. Andrews Space has been developing innovative space and aerospace systems for NASA, the Department of Defense, and commercial customers since the company’s inception in 1999. Andrews Space has been involved in initiatives including commercial crew and cargo, operationally responsive spacelift, NASA exploration, and hypersonic platforms. For more information please visit http://www.andrews-space.com.
About DCI Services and Consulting
Headquartered in Houston, TX, near the Johnson Space Center, DCI Services and Consulting is an engineering consulting firm focused on aerospace and systems engineering, technical management, and strategic business development. DCI is currently providing services to participants in NASA’s Commercial Crew Development Program and is engaged on topics such as safety standards for commercial spaceflight, commercial business models and procurement, and Space Station utilization. For more information please visit http://www.dci-sc.com.
About MEI Technologies
MEI Technologies, Inc. provides technical solutions to the commercial and federal technology markets. Founded in 1992 as Muñiz Engineering, the company employs more than 800 individuals that serve more than 60 clients in the civil, commercial and defense industries. Headquartered in Houston, the company operates satellite offices in seven additional states: Colorado (Denver and Colorado Springs), New Mexico (Albuquerque and White Sands Test Facility); Alabama (Huntsville), Maryland (Greenbelt), Georgia (Marietta), Mississippi (Stennis Space Center), and California (San Jose and Los Angeles). For more information please visit http://www.meitechinc.com.
About Special Aerospace Services
Headquartered in Boulder, Colorado, Special Aerospace Services is a small, woman-owned, innovative aerospace services and solutions company. Special Aerospace Services (SAS) provides experienced program support in the areas of launch vehicles, spacecraft systems, space system engineering, human rating and SpaceFlight Safety (TM). SAS supports U.S. and International customers, including NASA’s CCDev and COTS Programs, Defense Threat Reduction Agency, and commercial launch service providers. For more information please visit http://www.specialaerospaceservices.com.
About SRA International
Founded in 1978 and headquartered in Fairfax, Virginia, SRA provides the expert knowledge, technical tools and solutions that governments, agencies and companies need to improve performance, reduce costs and risks, introduce enterprise efficiencies and enhance human health. For complex space-based programs, SRA’s Intelligence & Space Sector delivers products and services at every phase – from mission concept through spacecraft retirement. For more information please visit http://www.sra.com.
# # #
Every three years the Librarian of Congress reviews the Digital Millennium Copyright Act (DMCA), and James H. Billington’s review just expanded digital freedom with this year’s ruling of new exemptions to the copyright law.
Jailbreak that iPhone
First and foremost, Billington ruled that it’s not against the law to jailbreak a phone (the practice of working around the device’s security system and taking more direct control of it). The Electronic Frontier Foundation lobbied hard for this, particularly with the iPhone in mind. Because Apple keeps tight reins on the device—offering only AT&T phone service and acting as gatekeeper for what apps can be added—many people had taken to jailbreaking the phone.
About 4 million iPhone and iPod Touch units had been jailbroken as of last August, and were accessing apps from a sort of black-market storefront called Cydia, the marketplace’s founder told Wired. The store is a haven for many developers that Apple, the gatekeeper to its App Store, has ignored or turned away [Los Angeles Times].
The ruling may be a victory for free use, but that doesn’t mean you should go out and jailbreak that iPhone straight away. Apple, which has staunchly opposed the legalization of jailbreaking, says it leaves the phone open to attacks and the user without access to software upgrades. Oh, and by the way, Steve Jobs and company will still void your warranty if you do it.
Circumventing copyright protection isn’t a crime—sometimes
Billington also ruled that breaking the copyright protection on DVDs is not, by itself, illegal. It’s what you do with it that matters.
College professors and students, documentary filmmakers, and those making noncommercial videos, are now able to circumvent the copyright protection on DVDs in order to use short clips from those DVDs in new works “for the purpose of criticism or comment” [PC World].
Simultaneously, a federal appeals court ruled much to the same effect in a case involving MGE UPS Inc., which makes backup power devices. The company sued after hackers figured out how to bypass a dongle system MGE developed, but the court dismissed the case saying that the act of hacking the system is not itself a violation of the law.
In other words, just circumventing the technology isn’t enough to get into trouble with the DMCA. The circumvention must lead to some violation of copyright [Ars Technica].
Video games and e-books
The rules on e-books have been updated, too. Many of them have restrictions on the read-aloud option, which book publishers wanted so that your e-book couldn’t double as an audio book. The Library of Congress made it legal to work around that restriction, but only if no audio book exists for that title (no matter what it costs).
And hacking video games is now OK, too, so long as you’re doing it for “good faith testing” of possible security problems.
Related Content:
DISCOVER: The Intellectual Property Fight That Could Kill Millions
80beats: iPhone Worms Move from Harmless (Rickroll) to Nasty (Stolen Bank Info)
80beats: Steve Jobs: There’s No iPhone “Antenna-Gate,” But Here’s a Free Case
Bad Astronomy: Resolving the iPhone Resolution
Image: Apple
Dear All, I have Evo N410c Notebook with wireless Lan card on the top. We have Wireless Lan in my office but it does'nt detect. Can anyone help me to get the settings and how those settings should b done in notebook.
hiee frdzz...!!
i want 2 make a vertical Axis wind mill of a low capacity 70W AC....
and i made a ROTOR for it...which gives 42 Rpm at no load at a normal condition...
now suggest me sum hint which machine i have to use to generate 70W..
...
for this rotor..the DC machine is
Particle physicists hunting for the Higgs boson reported their latest findings yesterday at the International Conference on High Energy Physics in Paris. The big two–Europe’s Large Hadron Collider and Fermilab’s Tevatron Collider (in Illinois)–gave updates, and other conference buzz included talk of a new facility, the International Linear Collider, which may one day give physicists a cleaner look at the other colliders’ results.
Large Hadron Collider — More Detailed Models Help the Search
Currently operating at 7 Tera electron Volts (TeV), the Large Hadron Collider is the world’s most powerful particle accelerator. Though electrical malfunctions hindered the collider in 2008, now LHC scientists report that they have made up for lost time: finding in months, what took the Tevatron, with its 2 TeV collisions, decades.
“The scientific community thought it would take one, maybe two years to get to this level, but it happened in three months,” said Guy Wormser, a top French physicist and chairman of the conference.[AFP]
As Symmetry (a Fermilab/SLAC publication) notes, these findings are more than a test of strength–or a simple retracing of the Tevatron’s footsteps. LHC physicists have to show that their facility can reproduce the results other machines have already seen, if one day they are to be sure that their data indicate something new.
As also reported by Symmetry, because the LHC is running at energies 3.5 times the Tevatron’s, these higher energies allow LHC physicists to refine their previous understandings, teasing out details impossible to see at lower energies. Such details may help physicists refine their search for the Higgs, the particle that presumably gives mass to all other particles.
CERN, the European umbrella organization that runs the LHC, says that these tests show the collider is ready for that search.
“Rediscovering our ‘old friends’ in the particle world shows that the LHC experiments are well prepared to enter new territory” said CERN’s Director-General Rolf Heuer. “It seems that the Standard Model is working as expected. Now it is down to nature to show us what is new.”[CERN]
Tevatron — Telling Physicists Where Not to Look
Meanwhile, Tevatron researchers have narrowed the expected mass of the missing particle. The diagram above shows the expected mass ranges, and those excluded by the new Tevatron data and previous Fermilab experiments. For reference, the proton has a mass of a little less than one GeV/c^2.
[P]hysicists’ standard model of the fundamental particle does not predict how much the Higgs itself will weigh. So scientists must go searching for it. Previous experiments show that it probably has a mass between 114 and 185 giga-electron volts (GeV), or 121 and 197 times the mass of the proton. Last year, experimenters working with D0 (aka DZero) and the Tevatron’s other particle detector, CDF [Collider Detector at Fermilab], took a chunk out of that possible range, reporting that the Higgs most likely does not weigh between 162 GeV and 166 GeV. Now, they’ve widened that “exclusion window” to between 158 GeV and 175 GeV.[Science Now]
Given such results, physicists have submitted a proposal to Fermilab asking that the Tevatron’s life be extended beyond 2011 to 2014, but the lab can’t guarantee that given its limited resources and other ongoing experiments and new projects.
Currently CERN officials have scheduled an LHC shutdown for 15 months also in 2011, which might give an operating Tevatron a chance to find the Higgs, Robert Roser of the Tevatron’s CDF detector told The Guardian.
“The LHC won’t be able to say anything about the Higgs particle until well into 2013. If we can run until 2014, we should be able to see the Higgs boson whatever mass it has,” said Roser. [The Guardian]
International Linear Collider — A Future, Cleaner Look?
Given results from the LHC and Fermilab, scientists continue to discuss new colliders, such as the International Linear Collider. Unlike the Tevatron and the LHC, which spin particles in a circle and then collide them, the International Linear Collider will force electrons and their antimatter-pair, positrons, to face off in a straight, approximately 20-mile long tube. Researchers say the collider would complement ongoing research at the LHC, by giving scientists a less powerful but cleaner look at the data, in part because the linear setup will ensure that particles that didn’t smash in the initial collision won’t continue circulating through the detector, Popular Science reports. They hope to start building the detector in 2012, but it will require international funding, the AP reports, amounting to $12.85 billion. Barry Barish, director of the proposed collider, told the AP:
“If we are going to build an ambitious machine, then it’s got to be a global machine.”[AP]
A video describing the ILC is available, here.
Related content:
80beats: LHC Sets a New Personal Record: 10,000 Particle Smash-Ups per Second
80beats: A Sweet Smashup: The LHC Shatters the Collison Energy Record
80beats: In 1 Week, the LHC Will Try to Earn the Title, “Big Bang Machine”
80beats: Rumors of the LHC’s Demise Have Been Greatly Exaggerated
80beats: LHC Beam Zooms Past 1 Trillion Electron Volts, Sets World Record
Images: CERN, Fermilab
Graphing variables is a critical skill in science. If something depends on something else — like the speed of sounds depends on air density, or the surface gravity of an object depends on its size — then if you plot the two things on a graph, you should see a pattern. The result is a line, or a curve. If the two things don’t depend on each other, you get a random collection of dots: a scatter plot.
About a hundred years ago, two astronomers plotted the brightness of stars against their color (from blue to red) and what they found was amazing: a clear connection between the two! In fact, stars fell into several groups, and over the years we’ve learned about why that happens. Most stars are stable, like the Sun, and fall into the Main Sequence of the plot. Some are old, some young, some dying, some dead. And they all have their place in what we now call the Hertzsprung-Russel diagram, or H-R diagram for short. It’s one of the most useful tools astronomers have ever created.
And now my friend Stuart who runs Astronomy Blog has done it one better: he’s created an H-R diagram of media stars. It’s awesome:
That’s really funny, and I wish I had thought of it. The vertical axis is fame, as denoted by Google results, and the horizontal axis is peer-reviewed papers. I’m actually only first author on I think two papers, but I was listed as author on a lot due to my work on Hubble. So I do OK on this diagram. I note that Brian Cox is more luminous than me, but then, he’s an actual rock star. If there were a branch for white main sequence stars, he and I would be in a dead heat.
Next up, I hope: a space-time diagram showing warping due to massive astronomers.
can any body explain me what is a earthlink
I have been asked to calculate the PSCC of a DC supply if the ff is been given,
100 cell battery full load
total internal resistance is 0,011 ohm
total resistance of the battery pole connectors 1 ohm
cable lenght is 100m
Cross sectiona
