Ultraviolet Vision May Enhance the Ability of Reindeer to Discriminate Plants in Snow

In reindeer/caribou (Rangifer tarandus), the lens and cornea of the eye transmit ultraviolet (UV) light, and the retinae respond to it electro-physiologically. Here we tie this finding to the unusual visual environment experienced by these animals and propose that their sensitivity to UV light enhances vision at the low luminance characteristic of the polar winter. For such visual enhancement to occur, it is essential that functional components of the environment, such as forage plants, be visually salient under natural UV luminance. However, it is not self-evident that this is the case. Although organic material generally absorbs UV radiation, powerful scattering of UV light by snow crystals may reduce the contrast with the background. We therefore recorded UV images of vegetation in situ on snow-covered pasture under natural winter (March) luminance in northern Norway. For each vegetation scene, we made three monochrome digital images, at 350 – 390 nm (UV-Only), 400 – 750 nm (No-UV), and 350 – 750 nm (control), respectively. Plants at the snow surface appeared in high achromatic contrast against snow in UV-Only images. The contrast was substantially greater in the UV-Only images than in corresponding images in which UV was blocked. We conclude that plants are visually salient under natural UV luminance at wavelengths to which Rangifer are sensitive. This sensitivity is likely to improve the animals’ ability to discriminate forage in snow, particularly at low but relatively UV-enriched twilight luminance.Le cristallin et la cornée de l’oeil du caribou (aussi connu sous le nom de renne) (Rangifer tarandus) transmettent une lumière ultraviolette (UV), à laquelle la rétine envoie une réponse électrophysiologique. Ici, nous faisons le lien entre cette observation et l’environnement visuel inhabituel de ces animaux, puis nous proposons que leur sensibilité à la lumière UV enrichit leur vision dans la faible luminance de l’hiver polaire. Pour que cet enrichissement ait lieu, il est essentiel que les composantes fonctionnelles de l’environnement, comme les plantes fourragères, soient visuellement saillantes sous la luminance UV naturelle. Il ne va cependant pas de soi que c’est le cas. Bien que la matière organique absorbe généralement le rayonnement ultraviolet, la diffusion puissante de la lumière UV découlant de la présence des cristaux de neige peut avoir pour effet de réduire le contraste avec l’arrière-plan. Par conséquent, nous avons enregistré des images ultraviolettes de la végétation in situ dans des pâturages couverts de neige sous la luminance naturelle de l’hiver (en mars), dans le nord de la Norvège. Pour chacune des scènes de végétation, nous avons fait trois images monochromes numériques, soit 350 à 390 nm (UV seulement), 400 à 750 nm (sans UV) et 350 à 750 nm (contrôlé), respectivement. Les plantes à la surface de la neige apparaissaient en fort contraste achromatique contre la neige dans le cas des images en UV seulement. Le contraste était beaucoup plus grand dans les images en UV seulement que dans les images correspondantes pour lesquelles l’UV était bloqué. Nous concluons que les plantes sont visuellement saillantes sous la luminance UV naturelle aux longueurs d’onde auxquelles le Rangifer est sensible. Cette sensibilité est susceptible d’améliorer l’aptitude de cet animal à distinguer le fourrage dans la neige, particulièrement en situation de faible luminance relativement enrichie en UV, au crépuscule

A comparative analysis on the in vivo toxicity of copper nanoparticles in three species of freshwater fish

Copper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and the acute toxicity of spherical 50 nm copper nanoparticles was assessed in juvenile rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas) and zebrafish (Danio rerio) for in vivo aqueous exposures following standardized OECD 203 guideline tests. The fate of the CuNPs in the aqueous media was temperature dependent. At the higher study temperature (26 ± 1 C), there was both an enhanced particle aggregation and higher rate of dissolution compared with that at the lower study temperature (15 ± 1 C). 96 h LC50s of the CuNPs were 0.68 ± 0.15, 0.28 ± 0.04 and 0.22 ± 0.08 mg Cu/L for rainbow trout, fathead minnow and zebrafish, respectively. The 96 h lowest-observed-effect concentration (LOEC) for the CuNPs were 0.17, 0.023 and Conservation Biolog

1999 Quadrantids and the lunar Na atmosphere

Enhancements of the Na emission and temperature from the lunar atmosphere were reported during the Leonids meteor showers of 1995, 1997 and 1998. Here we report a search for similar enhancement during the 1999 Quadrantids, which have the highest mass flux of any of the major streams. No enhancements were detected. We suggest that different chemical-physical properties of the Leonid and Quadrantid streams may be responsible for the difference.Comment: 5 pages, 1 figure, accepted for publication in MNRA

How European Union Membership Can Undermine the Rule of Law in Emerging Democracies

The European Union views the spread of economic prosperity and rule of law to countries emerging from dictatorship as among its primary goals when considering countries as candidates for membership. Existing literature often suggests that EU membership confers significant benefits on the accession countries, and these countries are willing to undergo costly and difficult reforms to reap these benefits. Through strict membership conditions, member states force accession countries to commit to democracy. Drawing on theoretical work in the fields of law, politics, and economics, this article reassesses the conventional wisdom. It argues that, under certain conditions, the reforms required of would-be members could have the perverse effect of undermining the establishment of legitimate law in transitional democracies. Using an agent-based model, the article elucidates a theory in which placing laws on the books around which no societal consensus exists can create perverse incentives for citizens and government officials and may lead to an erosion of the rule of law

How does visual language affect crossmodal plasticity and cochlear implant success?

Cochlear implants (CI) are the most successful intervention for ameliorating hearing loss in severely or profoundly deaf children. Despite this, educational performance in children with CI continues to lag behind their hearing peers. From animal models and human neuroimaging studies it has been proposed the integrative functions of auditory cortex are compromised by crossmodal plasticity. This has been argued to result partly from the use of a visual language. Here we argue that 'cochlear implant sensitive periods' comprise both auditory and language sensitive periods, and thus cannot be fully described with animal models. Despite prevailing assumptions, there is no evidence to link the use of a visual language to poorer CI outcome. Crossmodal reorganisation of auditory cortex occurs regardless of compensatory strategies, such as sign language, used by the deaf person. In contrast, language deprivation during early sensitive periods has been repeatedly linked to poor language outcomes. Language sensitive periods have largely been ignored when considering variation in CI outcome, leading to ill-founded recommendations concerning visual language in CI habilitation

Does congenital deafness affect the structural and functional architecture of primary visual cortex?

Deafness results in greater reliance on the remaining senses. It is unknown whether the cortical architecture of the intact senses is optimized to compensate for lost input. Here we performed widefield population receptive field (pRF) mapping of primary visual cortex (V1) with functional magnetic resonance imaging (fMRI) in hearing and congenitally deaf participants, all of whom had learnt sign language after the age of 10 years. We found larger pRFs encoding the peripheral visual field of deaf compared to hearing participants. This was likely driven by larger facilitatory center zones of the pRF profile concentrated in the near and far periphery in the deaf group. pRF density was comparable between groups, indicating pRFs overlapped more in the deaf group. This could suggest that a coarse coding strategy underlies enhanced peripheral visual skills in deaf people. Cortical thickness was also decreased in V1 in the deaf group. These findings suggest deafness causes structural and functional plasticity at the earliest stages of visual cortex

Toward Male Individualization with Rapidly Mutating Y-Chromosomal Short Tandem Repeats

Peer reviewe

Expanding the diversity of mycobacteriophages: insights into genome architecture and evolution.

Mycobacteriophages are viruses that infect mycobacterial hosts such as Mycobacterium smegmatis and Mycobacterium tuberculosis. All mycobacteriophages characterized to date are dsDNA tailed phages, and have either siphoviral or myoviral morphotypes. However, their genetic diversity is considerable, and although sixty-two genomes have been sequenced and comparatively analyzed, these likely represent only a small portion of the diversity of the mycobacteriophage population at large. Here we report the isolation, sequencing and comparative genomic analysis of 18 new mycobacteriophages isolated from geographically distinct locations within the United States. Although no clear correlation between location and genome type can be discerned, these genomes expand our knowledge of mycobacteriophage diversity and enhance our understanding of the roles of mobile elements in viral evolution. Expansion of the number of mycobacteriophages grouped within Cluster A provides insights into the basis of immune specificity in these temperate phages, and we also describe a novel example of apparent immunity theft. The isolation and genomic analysis of bacteriophages by freshman college students provides an example of an authentic research experience for novice scientists