Post List

  • January 18, 2011
  • 03:58 PM
  • 887 views

Leapin’ Blennies

by Kelsey in Mauka to Makai

In true science writer geekdom, I have spent the last week trying to figure out where the name “blenny” comes from. Of course, it comes from the suborder name Blenniodei (in the order Perciformes) and the family name Blenniidae…yada yada yada. But where does the blenn- come from? Most scientific names come from Latin, but [...]... Read more »

  • January 18, 2011
  • 03:45 PM
  • 1,228 views

GO EAST, YOUNG WHALE

by Julia Whitty in Deep Blue Home

(Photo from here.)A 13-year-old western Pacific gray whale (Eschrichtius robustus) is shining some light on the travels of his kind.Flex—as he's called by researchers—was tagged on 4 October on his summer feeding grounds in the Okhotsk Sea off Sakhalin Island, Russia. (Sakhalin Island. Image courtesy NASA's Earth Observatory.)Western Pacific gray whales are among the most endangered whales on Earth, with a population of only 113 to 130 individuals. In contrast, the gray whales who migrate along the western coast of North America—known as the eastern Pacific gray whales—comprise a population estimated at between 15,000 and 22,000 individuals.The good news is that as recently as 1972 Flex and the western grays were believed extinct. Still, the margins are thin. The IUCN Red List categorizes the western grays as critically endangered—the last stage before extinction: [B]ased on an extinction probability exceeding 50% within three generations, or a projected continuing decline of the subpopulation in combination with a mature population size less than 250. In addition, the small absolute subpopulation size, and the estimate of at most 35 reproductive females means that the subpopulation would easily qualify as Endangered. (Gray whale. Photo by Jim Borrowman, Straitwatch, courtesy NOAA.) Until now, no one has known where Flex and his kin go after leaving the Okhotsk Sea. At this time of year the eastern grays have migrated south to the breeding lagoons along Mexico's Baja Peninsula. But the western whales—or at least, Flex—show no signs of heading for warmer water. ... Read more »

Saraux, C., Le Bohec, C., Durant, J., Viblanc, V., Gauthier-Clerc, M., Beaune, D., Park, Y., Yoccoz, N., Stenseth, N., & Le Maho, Y. (2011) Reliability of flipper-banded penguins as indicators of climate change. Nature, 469(7329), 203-206. DOI: 10.1038/nature09630  

  • January 18, 2011
  • 02:05 PM
  • 881 views

Thrilled to have been selected for Open Lab 2011! Here is my post about jarringly awesome sex in earwigs:

by Dr. Carin Bondar in Dr. Carin Bondar - Biologist With a Twist



Size really does matter!  Well endowed male earwigs have their cake and eat it too…
~~
Many animal species employ a polyandrous sexual system, where one female mates with many males and stores sperm in a specialized storage organ.  Since fertilization doesn’t take place immediately (in some cases females can store viable sperm for several weeks), males [...]... Read more »

  • January 18, 2011
  • 01:57 PM
  • 2,182 views

The Emotional Depth of a Turnip—Do Men and Women Read Emotions Differently?

by Krystal D'Costa in Anthropology in Practice


She was clearly upset. The disgust on her face was apparent. As was her frustration when she shook her head at the man standing numbly beside her and said, "You have the emotional depth of a turnip!" The rest of us in the subway car did our best to look busy—headphones were put on, games were played on cell phones, even the morning newspaper made a few reappearances even though it was the evening rush hour.
I have to admit that I was somewhat amused by the situation because I'd recently directed this phrase at a male friend myself, albeit in a less charged environment. The subway man's response was interesting: He appeared bewildered. And the response was eerily similar to that of the recipient of my own statement (though in fairness he accepted my diagnosis with some grace). Admittedly, I don't know the cause of this couple's argument, and I certainly don't know anything about their personalities or the nature of their relationship. Still the perceived shared response made me pause. I don't mean to imply that all men lack complex emotional responses—emotions and relationships are difficult to analyze and label in broad, social terms. Appropriate social and emotional responses are often culturally driven, and produced to various degrees dependent on personality. Nonetheless, regardless of cultural association, some people, both male and female, seem more emotionally expressive and perceptive when compared to others—is there a biological explanation for this?
Possibly. But not in the way you would think.
Emotions are a conscious experience. They're physical and we know they're happening. Even when we incorrectly identify them (e.g., saying "I'm not angry!" when in fact you're furious), we still experience them. But researchers Winkielman and Berridge (2004) have suggested that in some cases, emotional processes may be unconscious, or implicit—that is, we may feel something without being aware that we're having the feeling or behaving in a certain way. We may be influenced by subliminal stimuli. For example, research participants were exposed to several expressive faces and asked to then either pour themselves a drink or rate the drink. After viewing happy expressions, participants were more likely to drink more and pay more for their drink, especially if they were in fact thirsty (122).  Participants were asked to rate their own mood and reported no changes, which suggests no awareness about changes in mood. This consequently implies that they were swayed by subliminal messaging.
Winkielman and Berridge argue that the evolutionary purpose of emotions is to regulate appropriate responses—it helps us negotiate our networks:Basic affective reactions are widely shared by animals, including reptiles and fish, and at least in some species may not involve conscious awareness comparable to that in humans. The original function of emotion was to allow the organism to react appropriately to positive or negative events, and conscious feelings might not always have been required (2004: 122).Basic affective responses, such as liking pleasant experiences or feeling fear in threatening situations, may be hardwired into our social circuitry. These responses are controlled by subcortical structures in the brain—such as the amygdala—which carry out preconscious operations. Anencephalic infants, for example, who possess only a brainstem still demonstrate positive reactions to agreeable experiences like tasting sugar, and negative reactions to tasting bitter items.
The role the amygdala plays in emotional response is not fully understood. As discussed above, there may be some connection between the amygdala and basic affective responses. Anderson and Phelps (2000) presented a case study of a patient known as SP who suffered from lesions in the region of the amydala. In tests that asked her to identify the emotions of others, she demonstrated a diminished sensitivity to interpreting disgust and happiness: Across patients, however, damage to the amygdala is most associated with impairments in the recognition of fear. Further, SP exhibited a pattern of impairment in the evaluation of expressions other than fear that is largely consistent with her extra-amygdalar damage in the right anteromedial temporal lobe. Thus, we conservatively assert that SP's deficits in recognizing expressions of fear are associated with lesions of her amygdala (Anderson and Phelps 2000: 108).There is some belief that the amygdala in particular may play a role in our ability to learn and interpret nonverbal social communication. Both Winkielman and Berridge (2004) and Anderson and Phelps (2000) make reference to the importance for nonhuman primates to recognize social displays of fear and suggest that these responses may be based in this structure: "fearful facial expressions may be important for learning to fear previously neutral environmental stimuli" (Anderson and Phelps 2000: 111).
However, I'm going to work with the assumption that both the subway man and my clueless friend have fully functional amydaloid regions. It's possible that there is a gender difference when it comes to emotional understanding and response. A recent article from Hoffman and colleagues (2010) reports that women are better at interpreting subtle emotional clues. When asked to appropriately label facially expressed emotions, women were significantly better at picking up on low intensity emotional cues, so a glance or a movement may be significant to woman in a way that's very different to a man. In light of the discussion by Winkielman and Berridge, I'll venture to say that women may be more likely to respond to subliminal stimuli as well. Men appear to have trouble distinguishing anger and sadness from each other at low intensity expressions—so men aren't likely to pick up that you're upset if you're silently fuming, ladies.
The reasons for this difference isn't clear. There isn't a clear biological divide as to why women may be more perceptive than men when it comes to emotions. Certainly socialization may play a role in emotional sensitivity. But is that all there is to it? Perhaps emotional sensitivity plays a role in our evolutionary history—in hierarchical groups, it would have been beneficial to be able to read the social cues of others, particularly when they ranked higher within the group. It could have potentially saved the lives of offspring, and assured continued group membership and protection. For example, knowing when to avoid the group's matriarch or the Alpha male, could have been useful knowledge to have.
In this case, and in my own experience, these studies highlight that that there is in fact the potential for a biological and social divide in communication between the sexes that goes beyond simple socialization. Again, this is not to suggest that all men are emotional turnips or that women are all hypersensitive and savvy to emotions, but it does advocate for a bit of patience on both of our parts—particularly in public confrontations.

Referenced:... Read more »

  • January 18, 2011
  • 01:56 PM
  • 1,103 views

Perceptual Learning Stabilises Action: A Test of the Bingham Model

by Andrew Wilson in Notes from Two Scientific Psychologists

Bingham's perception-action model was initially inspired by perceptual judgement studies (using vision and proprioception). The HKB phenomena are movement phenomena, however; simply noting that the same qualitative pattern is seen in different judgement and action studies is a good first step but only suggestive, at best. We therefore next took simultaneous judgement & action measures from a movement task where we manipulated the feedback display (Wilson et al, 2005a). For instance, when the display showed 0°, movement was stable, even when the movement was at, for example, 90°. Perception of relative phase was driving the stability of the movements. On the basis of all this data, the model predicts that the reason 0° and 180° are easy is that the information specifying that you are moving this way is easily perceived. There is provisional evidence to support relative direction of motion as the specifying information (Bogaerts et al, 2003; Wilson et al, 2005b; Wimmers et al, 1992) with relative speed acting as a noise term. This variable certainly predicts the observed pattern, as the relative direction of motion is only stable at 0° and 180°. It is maximally variable at 90°, which would explain why movements here are also maximally unstable. The model is therefore explaining the problem with moving at 90° as a problem detecting the information required to maintain the coordination; as we saw in the case of friction, no information means unstable behaviour. The model therefore makes a critical prediction. If we could improve people's ability to perceive 90°, they should gain the ability to move at 90° without any practice at the movement itself. All previous learning studies had entailed training people to move by having them move, with the help of various forms of transformed feedback methods (visual metronomes or Lissajous plots; more on this when I discuss feedback). The prediction, that movement stability should improve with improved perceptual ability, is a strong test of both the model and the modelling strategy in general, and the experiment to test it was the first half of my dissertation.The experiment itself was actually very straight-forward, although time consuming to run. BaselineWe took Baseline measures of action stability by having participants use a joystick to control a dot on the screen so as to move at 0°, 180° or 90° to an oscillating dot on the screen (Figure 1). We measured movement stability as the proportion of time spent at the target relative phase, +/- 20°. Everyone produced the standard HKB pattern (good movement stability at 0°, good but lower stability at 180°, terrible at 90°; see the black lines in Figure 3). We split the participants into two groups of 6 (Learning and Control), balanced according to their ability to move at 90°. Figure 1. Schematic of the setup for the action taskWe also took Baseline measures of perceptual ability at 90° and 180°. Participants viewed two displays, one moving at the target relative phase and the other at some different relative phase; the magnitude of the difference on each trial was randomly selected from 10 alternatives. This is a two-alternative forced choice (2AFC) psychophysical procedure, using a non-adaptive staircase. We computed the difference required before people could reliably tell the difference between the two displays (75% correct) and used this as an estimate of the threshold. See Figure 2. Figure 2. Schematic of the judgement task.Thresholds at 180° were approximately 11°, i.e. the displays needed to be different by 11° before participants could reliably tell the difference. Baseline thresholds for 90° were 24° - much higher, and also highly variable both within and between participant. This matches nicely to the original visual perception study results. TrainingWe then extensively trained the 6 people in the Learning group on the perceptual judgement task until their thresholds settled out and stopped changing. This took between 7 and 14 sessions, so the training was time consuming. The training had the participants make increasingly difficult discriminations of 90°; they received 'correct'/'incorrect' feedback and were shown 90° again when they made an error. There was no exposure to the movement task.Thresholds at 90° steadily decreased over training, and settled out at 12°, very similar to performance at 180°.Post Training and RetentionThese sessions repeated the Baseline; Post Training was at least 1 day after the final training session, and Retention was at least 1 week after.The question was simple: had the Learning group improved in their ability to move at 90°? What about the Control group, who did the same number of movement trials - had they improved at 90° just by trying the movement?The results were straightforward: only the Learning group improved their movement stability, and only at 90° (the learning did not generalise) - see Figure 3.Figure 3. Movement stability data from the three Assessment sessionsThe conclusion was straight-forward: the Learning group was able to use their improved perceptual ability to maintain movement stability. As we noted in the paper, this is not a case of learning generalising from the perceptual to the action domain: there is only the perception-action domain, and the training altered the perception-action system. This experiment, therefore, clearly demonstrated that movement stability is a function of perceptual ability; 0° isn't stable because there's an attractor there (as per the dynamic pattern hypothesis), there's an attractor there because 0° is stably perceived!Some commentsThere were two ways, in principle, that the perceptual learning might have helped perceive 90°. First, the training could have improved people's discrimination of the relative direction of motion. However, we noted that at 90° this is unavoidably variable and noisy, and so it might not be possible to ever improve detection of it. The alternative is to learn to use a new information variable, one which is detectable and specifies 90°. In support of this, perceptual learning at 90° did not transfer to perceptual or action performance at 0° or 180°. We directly tested this in the second half of my dissertation, which I ... Read more »

Wilson, A., Snapp-Childs, W., & Bingham, G. (2010) Perceptual learning immediately yields new stable motor coordination. Journal of Experimental Psychology: Human Perception and Performance, 36(6), 1508-1514. DOI: 10.1037/a0020412  

  • January 18, 2011
  • 01:13 PM
  • 809 views

Antisocial Personality Disorder: Demon Doctors

by Stas Sajin in Raving Psychology

This is my second article in the series on antisocial personality disorder, which because of my unduly sloth has not been completed yet. The first post can be found by clicking on the link below: 1. History of the Antisocial Personality Disorder – up to 20th century — Those diagnosed with antisocial personality disorder (APD), a [...]... Read more »

Swanger, Andrew J. (1998) Japanese scientists conducted biological research experiments. World War II, 13(2), 62. info:/

  • January 18, 2011
  • 01:09 PM
  • 1,517 views

RNAi in the Nucleus ~ It’s no longer limited to the cytoplasm

by Linda in the Node

Hot off the press from the holidays is an article from PNAS that’s worth a gander if you’re into RNAi. We know RNAi associated with epigenetics is possible in the nucleus (Somehow, siRNAs could trigger the methylation and silencing of genes in the nucleus.) However, one soy bean group was able to provide evidence for [...]... Read more »

Hoffer, P., Ivashuta, S., Pontes, O., Vitins, A., Pikaard, C., Mroczka, A., Wagner, N., & Voelker, T. (2010) Posttranscriptional gene silencing in nuclei. Proceedings of the National Academy of Sciences, 108(1), 409-414. DOI: 10.1073/pnas.1009805108  

Guang, S., Bochner, A., Pavelec, D., Burkhart, K., Harding, S., Lachowiec, J., & Kennedy, S. (2008) An Argonaute Transports siRNAs from the Cytoplasm to the Nucleus. Science, 321(5888), 537-541. DOI: 10.1126/science.1157647  

Heinrichs, A. (2008) Gene expression: Argonaute on the move. Nature Reviews Molecular Cell Biology, 9(9), 666-666. DOI: 10.1038/nrm2473  

  • January 18, 2011
  • 12:31 PM
  • 1,247 views

Nextera™ sample prep enables breakthrough study of copy-number variation

by epibio in EpiCentral

The study of copy-number variation (CNV) in humans has contributed to our understanding of genetic uniqueness, as well as disease. Until recently, it was difficult to assess the number of repeated DNA sequences in the genome. In a recent publication, researchers at the 1000 Genomes Project and collaborators have invented new methods to study and find repetitive DNA sequences in the human genome, and have found that CNVs occur in only 7%-9% of human genes. They used the new techniques to compare the entire genomes of 159 individuals and were able to accurately assay previously unidentified duplicated genes.

For sequencing, the researchers picked and cultured 144 fosmid clones (from libraries prepared by shotgun cloning of genomic DNA) from eight selected individuals. After fosmid DNA purification, clone DNA was arrayed in a 96-well plate (two clones combined from unrelated loci for some). Bar-coded sequencing libraries were created separately from each well using the Nextera DNA Sample Prep Kit (Illumina-compatible), using 100 ng of fosmid DNA per well as the starting material. The 96 bar-coded Nextera libraries were pooled and sequenced on two lanes of an Illumina GAII (paired-end, 2 x 76-bp reads, with an additional 9-bp index read). Reads were mapped to the genome and analyzed as described in the supplementary information.

The authors report:
"We identified 4.1 million ‘singly unique nucleotide’ positions informative in distinguishing specific copies…these data identify human-specific expansions in genes associated with brain development, reveal extensive population genetic diversity, and detect signatures consistent with gene conversion in the human species. Our approach makes ~1000 genes accessible to genetic studies of disease association."
Sudmant, P. et al. (2010). Diversity of Human Copy Number Variation and Multicopy Genes Science, 330 (6004), 641-646 DOI: 10.1126/science.1197005... Read more »

  • January 18, 2011
  • 11:53 AM
  • 716 views

Are petro-states more aggressive?

by Henrik Karlstrøm in STS Guru

Discussing an interesting but seriously flawed article on the link between resources, political stability and aggresion... Read more »

  • January 18, 2011
  • 11:36 AM
  • 86 views

Labelling

by rattitude in Caring Carnivore

Labelling alerts consumers to qualities of the food that are not apparent from its intrinsic appearance.  these qualities are referred to variously as imperceptible, intrinsic or unobservable--and may include statuses such as 'organic' or 'genetically modified'. Concern about these qualities is termed "ethical preference". In the absence of labelling or other information that informs ethical choices, consumer are likely to feel less trust in the product. (Michalopoulos et al, 2008).Understandably, makers of products that many consumers have an ethical aversion (e.g. GM salmon) to tend to resist providing or allowing others to provide labelling relating to the underlying imperceptible quality.Michalopoulos, T., Korthals, M., & Hogeveen, H. (2007). Trading “Ethical Preferences” in the Market: Outline of a Politically Liberal Framework for the Ethical Characterization of Foods Journal of Agricultural and Environmental Ethics, 21 (1), 3-27 DOI: 10.1007/s10806-007-9059-4... Read more »

  • January 18, 2011
  • 10:52 AM
  • 1,314 views

Eocene Florida Plant Remains = Rethink Local Geology A Little

by Greg Laden in Greg Laden's Blog

Sometimes interesting scientific evidence shows up in unexpected places. Years ago, there had been discussion of the possibility that immediate post glacial climate in the North Atlantic coastal region was unusually warm, but the evidence was spotty. Then, I was looking through material taken from a geotechnical boring placed to assess the geology of a part of Boston Harbor where a new tunnel was being planned, and found a large fragment of a clam embedded in clay. The clay was deposited during the last glacial maximum and later, and was associated with the melting of glaciers in the region. As a matter of routine, I gave it to Russell Barber, a mollusk expert and, at the time, my boss. He identified it as a species of razor clam found these days no farther north than the Carolinas. And thus, yet another piece of spotty evidence! Read the rest of this post... | Read the comments on this post...... Read more »

Jarzen, David, & Klug, Curtis. (2010) A preliminary investigation of a lower to middle Eocene palynoflora from Pine Island, Florida, USA . Palylnology, 34(2), 164-179. info:/10.1080/01916121003737421

  • January 18, 2011
  • 10:35 AM
  • 1,613 views

Bushbuck: two species where there was one

by davesbrain in Dave Hubble's ecology spot

Back in the day, the bushbuck was considered a single species, Tragelaphus scriptus, found in various habitats across much of sub-Saharan Africa. Recently however, genetic studies have indicated that T. scriptus is actually a complex of two distinct species, the Kéwel (T. scriptus) and the Imbabala (T. sylvaticus). This evidence shows that these two bushbuck species are more closely related to other tragelaphines than to each other; the Imbabala being closest to the Bongo (T. eurycerus) and Sitatunga (T. spekeii), and the Kéwel to the Nyala (T. angasii) (Moodley et al. 2009).The Kéwel is found from West Africa, across the Sahel into East Africa, and as far south as Angola and the Democratic Republic of Congo (DRC). Meanwhile, the Imbabala is found from the Cape northwards to Angola, Zambia and East Africa, meaning that the two species’ ranges overlap in parts of Angola, DRC and East Africa. The Kéwel is the smaller of the two, and shows clear stripes and patterning on a reddish to yellowish background; there is little or no sexual dimorphism in this ground colour. In contrast, the Imbabala shows considerable colour variation with geography and habitat, especially in males (yellow to red-brown, through brown and olive to almost black), and only the most genetically ancient of populations (from Angola, Zambia, southern DRC, Botswana and northern Zimbabwe) have any significant striping. Even in these cases the horizontal stripe, where it exists, is formed of a series of spots rather than the solid striping of the Kéwel. never occurs. Mountain-dwelling forms of the Imbabala (Gregory Rift Highlands, Mt. Elgon, Imatong Mountains and Ethiopian Highlands) appear larger and are dark with little or no pattern. Until recently, most bushbuck studies focused on the Imbabala, hence little was known about the biology of the Kéwel beyond what could be obtained from museum specimens and hunting trophies.Imbalala bushbuck from Zimbabwe (courtesy of Graeme Guy). For a kewel image from The Gambia see here.Both species are primarily browsers, but will eat other plant matter too. They can be active at any time of day, although are more likely to be nocturnal near humans; their most active times are however early morning and parts of the night, so may appear nocturnal in any case. Most are solitary, with some living in pairs; all have a ‘home range’ of around 5 hectares in the savannah (larger in forests), although these ranges do overlap. Although the split into two species is fairly well understood (even if most non-scientific sources still refer to a single ‘bushbuck’), the more detailed taxonomy remains disputed with numerous potential subspecies and ecotypes having been described. For example, analysis of mt-DNA sequences (cytochrome b and control region) by Moodley & Bruford (2007) identified 23 phylogenetically distinct groups (‘ecotypes’) whose distribution correlated well with the pan-African eco-regions described by Olsen et al. (2001). 19 of these ecotypes corresponded with previously suggested subspecies, while six other haplotypes were newly recognized forms in the Volta region, Niger, Angola. and Luangwa and Zambesi Valleys. However, further research is onging to clarify the taxonomic status of bushbuck species, subspecies and ecotypes, so the situation is likely to remain somewhat fluid for a while – however, this does provide an opportunity to link the use of genetics in taxonomy to large-scale conservation in Africa, given the widespread distribution of bushbuck (in the broad sense) and apparent more local/region distribution of subspecies and ecotypes (Wronski 2009).ReferencesMoodley, Y. & Bruford, M.W. (2007). Molecular Biogeography: Towards an Integrated Framework for Conserving Pan-African Biodiversity. PLoS ONE 2(5): e454. doi:10.1371/journal.pone.0000454Moodley, Y., Bruford, M., Bleidorn, C., Wronski, T., Apio, A., & Plath, M. (2009). Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex Mammalian Biology - Zeitschrift fur Saugetierkunde, 74 (5), 418-422 DOI: 10.1016/j.mambio.2008.05.003Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D. & Powell, G.V.N. (2001). Terrestrial ecoregions of the world: a new map of life on earth. BioScience 51: 933-937. Wronski, T. (2009). Bushbuck, harnessed antelope or both? Gnusletter 28(1): 17-19.... Read more »

Moodley, Y., Bruford, M., Bleidorn, C., Wronski, T., Apio, A., & Plath, M. (2009) Analysis of mitochondrial DNA data reveals non-monophyly in the bushbuck (Tragelaphus scriptus) complex. Mammalian Biology - Zeitschrift fur Saugetierkunde, 74(5), 418-422. DOI: 10.1016/j.mambio.2008.05.003  

  • January 18, 2011
  • 10:14 AM
  • 801 views

Using Fear to Flirt: The “Scary Movie Effect”

by Rob Mitchum in ScienceLife

The Friday the 13th and Nightmare on Elm Street movies aren’t typically thought of as mating strategies. But putting on a scary movie is a trick as old as drive-in theaters for encouraging one’s date to jump in fright and snuggle in just a little bit closer. Birds, so far as we know, aren’t into [...]... Read more »

  • January 18, 2011
  • 10:09 AM
  • 1,656 views

This Week in the Universe: January 11th – January 17th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Planck’s Early Results
Planck Collaboration (2011). Planck Early Results: The Planck mission arXiv arXiv: 1101.2022v1
The Early Results Papers from the Planck Collaboration are based on the data acquired by the Planck satellite between August 13th, 2009 to June 6th, 2010.  This work is “an overview of the history of Planck in its first year of operations” and was released along side Planck’s Early Release Compact Source Catalogue, “the first data product based on Planck to be released publicly”.  Andrew Jaffe has a great summary of the results so far.
For more, see Planck: First results.

Dark Galaxies?
Sukanya Chakrabarti, Frank Bigiel, Philip Chang, & Leo Blitz (2011). Finding Dark Galaxies From Their Tidal Imprints arXiv arXiv: 1101.0815v1
From the abstract:
We describe ongoing work on a new method that allows one to determine the mass and relative position (in galactocentric radius and azimuth) of galactic companions purely from analysis of observed disturbances in gas disks….This approach has broad implications for many areas of astrophysics — for the indirect detection of dark matter (or dark-matter dominated dwarf galaxies), and for galaxy evolution in its use as a decipher for the dynamical impact of satellites on galactic disks. Here, we provide a proof of principle of the method by applying it to infer and quantitatively characterize optically visible galactic companions of local spirals, from the analysis of observed disturbances in outer gas disks.”
The tl;dr version is that they have a technique for detecting companion galaxies that need not be optically visible (which is great, because sometimes we can’t see things for reasons other than them being made out of dark matter) and this paper acts as a proof of concept by using it to correctly infer and characterize galaxies that we already can observe.  Does it say anything about having detected a dark matter galaxy? No.  If such things existed it could be used to detect them (if they were acting as companion to regular matter galaxies), but it doesn’t say anything about their existence.  I genuinely feel I read a different paper than the authors who wrote the below two articles.
For more, see Dark-Matter Galaxy Detected: Hidden Dwarf Lurks Nearby?, The Milky Way might be surrounded by invisible dark matter galaxies.
Not So Standard Standard Candle
This image layout illustrates how NASA's Spitzer Space Telescope was able to show that a "standard candle" used to measure cosmological distances is shrinking -- a finding that affects precise measurements of the age, size and expansion rate of our universe. Image credit: NASA/JPL-Caltech/Iowa State
From the NASA press release:
Astronomers have turned up the first direct proof that “standard candles” used to illuminate the size of the universe, termed Cepheids, shrink in mass, making them not quite as standard as once thought. The findings, made with NASA’s Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age and expansion rate of our universe.
Obviously, this is rather significant, but the immediate consequence of standard candles not being standard isn’t that it will allow for accurate future measurements of things, it’s that it calls into question the current measurements we have (for things like galactic distances).
From lead author of the study, Massimo Marengo*:
When using Cepheids as standard candles, we must be extra careful because, much like actual candles, they are consumed as they burn.
*He’s also an author on a wonderfully titled paper, Close Binaries with Infrared Excess: Destroyers of Worlds?.
For more, see Cosmology Standard Candle not so Standard After All.
Dynamical Coupled Dark Energy?

Baldi, M., & Pettorino, V. (2011). High-z massive clusters as a test for dynamical coupled dark energy Monthly Notices of the Royal Astronomical Society: Letters DOI: 10.1111/j.1745-3933.2010.00975.x
Abstract:
The recent detection by Jee et al. of the massive cluster XMMU J2235.3−2557 at a redshift z≈ 1.4, with an estimated mass M324= (6.4 ± 1.2) × 1014 M⊙, has been claimed to be a possible challenge to the standard ΛCDM cosmological model. More specifically, the probability to detect such a cluster has been estimated to be ∼0.005 if a ΛCDM model with Gaussian initial conditions is assumed, resulting in a 3σ discrepancy from the standard cosmological model. In this Letter we propose to use high-redshift clusters as the one detected in Jee et al. to compare the cosmological constant scenario with interacting dark energy models. We show that coupled dark energy models, where an interaction is present between dark energy and cold dark matter, can significantly enhance the probability to observe very massive clusters at high redshift.
So I actually haven’t read this paper yet, but was told by a cosmologist frien... Read more »

Planck Collaboration. (2011) Planck Early Results: The Planck mission. arXiv. arXiv: 1101.2022v1

Sukanya Chakrabarti, Frank Bigiel, Philip Chang, & Leo Blitz. (2011) Finding Dark Galaxies From Their Tidal Imprints. arXiv. arXiv: 1101.0815v1

  • January 18, 2011
  • 10:00 AM
  • 2,522 views

How does the body use DNA as an antimicrobial agent?

by Brooke N in Smaller Questions

Brief description of neutrophil NET's and current research.... Read more »

  • January 18, 2011
  • 09:21 AM
  • 994 views

Physics of the Riemann Hypothesis

by Marco Frasca in The Gauge Connection

In this blog I discuss frequently about one of the Clay Institute’s Millenium Prize problems: Mass gap and existence of a quantum Yang-Mills theory. Sometime I also used the Perelman’s theorem containing Poincarè’s conjecture to discuss about some properties of quanum gravity and also Cramer-Rao statistical bound. Today on arxiv I have found a beautiful [...]... Read more »

Daniel Schumayer, & David A. W. Hutchinson. (2011) Physics of the Riemann Hypothesis. arxiv. arXiv: 1101.3116v1

  • January 18, 2011
  • 09:05 AM
  • 1,107 views

Evolution's Rainbow, from sparrows' stripes to lizard lesbianism

by Jeremy Yoder in Denim and Tweed

Evolutionary biology is not just the study of how living things change over time, but the study of how the diversity of living things changes over time. Diversity is the raw material sculpted by natural selection, carved into more-or-less discrete chunks by speciation, and lost forever in extinction.

Joan Roughgarden is even more preoccupied with diversity than most evolutionary biologists. Some of her earliest published studies examine the evolution of optimum niche width, the range of resources a species uses, using mathematical modeling [$a] and empirical studies of resource and habitat use in Anolis lizards [$a]. Roughgarden didn't treat a species as a uniform group, but a collection of individuals all making a living in slightly different ways. Among other subjects, her work informed thinking about ecological release, the changes that reshape populations freed from predators or competitors.

.flickr-photo { }.flickr-framewide { float: right; text-align: left; margin-left: 15px; margin-bottom: 15px; width:100%;}.flickr-caption { font-size: 0.8em; margin-top: 0px; } White-throated sparrows are just one species with more than two gender roles. Photo by hjhipster.This interest in the evolutionary context of diversity would eventually become much more personal. In 1998, she came out as transgendered, taking the name Joan after decades spent establishing her scientific reputation under the name she was given at birth, Jonathan. In addition to the challenges inherent to gender transition, Roughgarden's expertise intersects with her identity in one awkward question: in a biological world shaped by natural selection, how can we explain the evolution of lesbians, gay men, and transgendered people—individuals who are not interested in sexual activity that passes on their genes?

Roughgarden's answer was to begin a program of research questioning the dominant way of thinking about sex in an evolutionary context. In 2004, she presented her conclusions comprehensively in the book Evolution's Rainbow, calling for biologists to re-think they way they understood and described sexual behavior throughout the animal kingdom. As another biologist with an admitted personal interest in the question, I've found Evolution's Rainbow to be a great starting point for thinking about sexuality in an evolutionary context.

Human sexuality as one stripe in nature's rainbow

.flickr-photo { }.flickr-frameright2 { float: right; text-align: left; margin-left: 15px; margin-bottom: 15px; width:25%;}.flickr-caption { font-size: 0.8em; margin-top: 0px; } Cover image from Google Books.Evolution's Rainbow takes aim at the idea that most sexual species are divided into neat, binary reproductive roles, in which males aggressively court females who judge them to find the healthiest mate—a model with little room for same-sex attractions, or more than two gender roles. Darwin conceived of this sexual selection to explain traits and behaviors that did not improve an individual's odds of survival—or, indeed, could even reduce them—but that were, he suggested, involved in demonstrating a male's health and virility.

However, Darwin's very Victorian thinking doesn't have much place for same-sex sexuality, or gender roles outside the male-female binary. Roughgarden argued that sexuality in the animal kingdom is much more varied than the aggressive males-choosy females binary. She holds that this diversity of behavior is better explained by a new model, which she terms social selection. The first several chapters of the book are dominated by the first of these points, and Roughgarden rounds up a tremendous array of sexual behaviors. To highlight just three that particularly struck me:

White-throated sparrows (pictured above) have evolved social roles separate from their sexual roles. Male and female white-throated sparrows may have one of two plumage morphs, each associated with different levels of aggressiveness—sparrows with bright white facial stripes sing and respond to other sparrows' songs to defend a nesting territory; birds with duller, "tan" stripes sing less frequently and are less territorial. Mated pairs of sparrows are most successful when they're mixed, but it doesn't matter whether the male or the female in a pair is the aggressive one. Mated pairings between tan-striped males and white-striped females have just as many chicks [$a] as pairings between white-striped males and tan-striped females. Roughgarden proposes that, like the sparrows' stripes, many traits biologists have understood to be signals for sexual roles are actually signaling social roles that need not be strictly associated with males or females.

.flickr-photo { }.flickr-frameright { float: right; text-align: left; margin-left: 15px; margin-bottom: 15px; width:40%;}.flickr-caption { font-size: 0.8em; margin-top: 0px; } Are smaller bluegill males "sneakers," or helpers? Photo by IcK9s.To take another example, male bluegill sunfish may follow one of two developmental pathways, with differing reproductive strategies. Some male bluegills—large males—do not reproduce until they grow big enough to defend a nesting territory; females lay eggs in territories defended by males they favor. Other male bluegills begin their reproductive lives at a much smaller size, by fertilizing unattended eggs in the large males' territories whenever they get the chance. As they grow larger, though, these now-medium-sized males change strategies—they join in the large males' courtship of females, and fertilize some of the eggs laid in the large males' territory. Medium males' coloration resembles that of female bluegills, and their strategy has been described as deceptive, mimicking females to "cuckold" large males [PDF]. Roughgarden favors another explanation: that medium males are collaborating with large males [$a], helping to attract females in return for a chance to reproduce.

Finally, in several species of whiptail lizards, females have evolved that don't need males to reproduce—their eggs are fertile without sperm. Yet these parthenogenetic females copulate with each other, and this same-sex activity helps to stimulate egg-laying. Parthenogenetic females form longer-term associations and share burrows [$a], which is much less common in related, sexually-reproducing species. Roughgarden suggests that for parthenogenetic whiptails, sex has an important role in social interaction even though its reproductive function is diminished.

.flickr-photo { }.flickr-framewide { float: right; text-align: left; margin-left: 15px; margin-bottom: 15px; width:100%;}.flickr-caption { font-size: 0.8em; margin-top: 0px; }... Read more »

Clutton-Brock, T. (2007) Sexual selection in males and females. Science, 318(5858), 1882-5. DOI: 10.1126/science.1133311  

Roughgarden, J. (1972) Evolution of niche width. The American Naturalist, 106(952), 683-718. DOI: 10.1086/282807  

  • January 18, 2011
  • 09:00 AM
  • 1,306 views

The genetics and phenotypes of the Jamaican click beetle (Adaptive Recursion II)

by Kele in Kele's Science Blog

In my last post I started a new short series on some biologists’ attempts to solve what they call an “adaptive recursion” or in other words, to know the full story of a trait from the bottom level of the gene to the top levels of ecology and differential fitness. Ecological descriptions frequently become “just-so [...]... Read more »

Stolz U, Velez S, Wood KV, Wood M, & Feder JL. (2003) Darwinian natural selection for orange bioluminescent color in a Jamaican click beetle. Proceedings of the National Academy of Sciences of the United States of America, 100(25), 14955-9. PMID: 14623957  

  • January 18, 2011
  • 08:27 AM
  • 1,073 views

Evolving Linguistic Replicators: Major Transitions and Grammaticalisation

by Wintz in A Replicated Typo 2.0

Just before Christmas I found myself in the pub speaking to Sean about his work on bilingualism, major transitions and the contrast between language change and the cultural evolution of language. Now, other than revealing that our social time is spent discussing our university work, the conversation brought up a distinction not often made: whilst language change is part of language evolution, the latter is also what we consider to be a major transition. As you evolutionary biologists will know, this concept is perhaps best examined and almost certainly popularised in Maynard Smith & Szathmáry’s (1995) The Major Transitions in Evolution. Here, the authors are not promoting the fallacy of guided evolution, where the inevitable consequence is increased and universal complexity. Their thesis is more subtle: that some lineages become more complex over time, with this increase being attributable to the way in which genetic information is transmitted between generations. In particular, they note eight transitions in the evolution of life:... Read more »

  • January 18, 2011
  • 07:49 AM
  • 1,374 views

Fact or fallacy, a survey of immunisation statements in the print media

by Grant Jacobs in Code for life






Most of us know anecdotally that print media on occasion present immunisation information incorrectly, but you can’t put a finger on how often and when without hard numbers.
A recent research article examining New Zealand newspapers puts numbers to the errors.
Helen Petousis-Harris led a team surveying the immunisation statements in articles printed in four national New Zealand newspapers [...]... Read more »

Petousis-Harris, H., Goodyear-Smith, F., Kameshwar, K., & Turner, N. (2010) Fact or fallacy? Immunisation arguments in the New Zealand print media. Australian and New Zealand Journal of Public Health, 34(5), 521-526. DOI: 10.1111/j.1753-6405.2010.00601.x  

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