903 research outputs found
Avian Malaria Among House Sparrows: a Survey of Disease and Mosquito Vectors (Diptera: Culicidae) in Reed City, Michigan
Nine of 350 house sparrows caught in Reed City, Michigan, had malaria parasites detectable on Giemsa-stained thin films. All of the infected birds were juveniles, Parasitemias were too low to permit identification of the Plasmodium present. Collection of potential vector mosquitoes showed that Culex pipiens and Culex restuans were present, but in low numbers
The charge and energy spectra of heavy cosmic ray nuclei
A charged particle detector array flown in a high altitude balloon detected and measured some 30,000 cosmic ray nuclei with Z greater than or equal to 12. The charge spectrum at the top of the atmosphere for nuclei with E greater than 650 MeV/n and the energy spectrum for 650 less than or equal to E less than 1800 MeV/n are reported and compared with previously published results. The charge spectrum at the source of cosmic rays is deduced from these data and compared with a recent compilation of galactic abundances
Outdoor music festivals: Cacophonous consumption or melodious moderation?
Large outdoor music festivals have emerged as part of a general expansion of licensed recreational activities, but in research terms they have been largely impenetrable due to commercial sensitivities. These sensitivities notwithstanding, the number and scale of such events necessitate a greater understanding of alcohol and drug use and the potential to promote normative protective behaviours in this context. This study examines self-reported alcohol and drug behaviours of 1589 attendees at a music festival in Scotland during the summer of 2008. Similarities between the outdoor rock music festivals and the dance club scene are considered alongside the challenges associated with risk reduction in these settings. Results show that alcohol was consumed by the majority of samples; however, negative consequences were reported by a minority of respondents, suggesting evidence of controlled hedonism within a situation traditionally associated with unrestrained excess. Similarly, the majority of samples did not use drugs. The majority also report a number of self-regulating protective behaviours suggesting that alcohol and drug use is contained within a developing social culture of ‘controlled intoxication’. Results further suggest that although music festivals are transitory events, there is a degree of consistency amongst attendees. Music festivals may therefore be atypical but potentially effective environments to increase protective behaviours using normative messaging and modern communications media. This study was resourced exclusively by local alcohol and drug partnerships
Electrostatics in wind-blown sand
Wind-blown sand, or "saltation," is an important geological process, and the
primary source of atmospheric dust aerosols. Significant discrepancies exist
between classical saltation theory and measurements. We show here that these
discrepancies can be resolved by the inclusion of sand electrification in a
physically based saltation model. Indeed, we find that electric forces enhance
the concentration of saltating particles and cause them to travel closer to the
surface, in agreement with measurements. Our results thus indicate that sand
electrification plays an important role in saltation.Comment: 4 journal pages, 5 figures, and supplementary material. Article is in
press at PR
Impact of Energy Crops on Soil Management and Erosion
Energy crops are perennials that require less cultivation and inputs than conventional crops, and are low maintenance harvest crops used for biofuels
2-[2-Benzoyl-3,3-bis(methylsulfanyl)prop-2-enylidene]malononitrile
The title compound, C15H12N2OS2, is an example of a push–pull butadiene in which the electron-releasing methylsulfanyl groups and electron-withdrawing nitrile groups on either end of the butadiene chain enhance the conjugation in the system. Short intramolecular C—H⋯S interactions are observed. In the crystal structure, an O⋯C short contact of 2.917 (3) Å is observed
Investigation of cell adhesion in chitosan membranes for peripheral nerve regeneration
Peripheral nerve injuries have produced major concerns in regenerative medicine for several years, as the recovery of normal nerve function continues to be a significant clinical challenge. Chitosan (CHT), because of its good biocompatibility, biodegradability and physicochemical properties, has been widely used as a biomaterial in tissue engineering scaffolding. In this study, CHT membranes were produced with three different Degrees of Acetylation (DA), envisioning its application in peripheral nerve regeneration. The three CHT membranes (DA I: 1%, DA II: 2%, DA III: 5%) were extensively characterized and were found to have a smooth and flat surface, with DA III membrane having slightly higher roughness and surface energy. All the membranes presented suitable mechanical properties and did not show any signs of calcification after SBF test. Biodegradability was similar for all samples, and adequate to physically support neurite outgrowth. The in vitro cell culture results indicate selective cell adhesion. The CHT membranes favoured Schwann cells invasion and proliferation, with a display of appropriate cytoskeletal morphology. At the same time they presented low fibroblast infiltration. This fact may be greatly beneficial for the prevention of fibrotic tissue formation, a common phenomenon impairing peripheral nerve regeneration. The great deal of results obtained during this work permitted to select the formulation with the greatest potential for further biological tests.This work has received funding from the European Community's Seventh Framework Programme (FP7-HEALTH-2011) under grant agreement no 278612 (BIOHYBRID). This study was also funded by European Union's FP7 Programme under grant agreement no REGPOT-CT2012-316331-POLARIS.The authors thank the chitosan raw material provided by Altakitin S.A., (Lisboa, Portugal). We are further thankful to Silke Fischer, Natascha Heidrich, Kerstin Kuhlemann, Jennifer Metzen, Hildegard Streich and Maike Wesemann (all from the Institute of Neuroanatomy, Hannover Medical School) for their technical support
Depurination of Brome mosaic virus RNA3 inhibits its packaging into virus particles
Packaging of the segmented RNA genome of Brome mosaic virus (BMV) into discrete particles is an essential step in the virus life cycle; however, questions remain regarding the mechanism of RNA packaging and the degree to which the viral coat protein controls the process. In this study, we used a plant-derived glycosidase, Pokeweed antiviral protein, to remove 14 specific bases from BMV RNA3 to examine the effect of depurination on virus assembly. Depurination of A771 within ORF3 and A1006 in the intergenic region inhibited coat protein binding and prevented RNA3 incorporation into particles. The disruption of interaction was not based on sequence identity, as mutation of these two purines to pyrimidines did not decrease coat protein-binding affinity. Rather, we suggest that base removal results in decreased thermodynamic stability of local RNA structures required for packaging, and that this instability is detected by coat protein. These results describe a new level of discrimination by coat protein, whereby it recognizes damage to specific viral RNA elements in the form of base removal and selects against incorporating the RNA into particles
Statistical mechanics of secondary structures formed by random RNA sequences
The formation of secondary structures by a random RNA sequence is studied as
a model system for the sequence-structure problem omnipresent in biopolymers.
Several toy energy models are introduced to allow detailed analytical and
numerical studies. First, a two-replica calculation is performed. By mapping
the two-replica problem to the denaturation of a single homogeneous RNA in
6-dimensional embedding space, we show that sequence disorder is perturbatively
irrelevant, i.e., an RNA molecule with weak sequence disorder is in a molten
phase where many secondary structures with comparable total energy coexist. A
numerical study of various models at high temperature reproduces behaviors
characteristic of the molten phase. On the other hand, a scaling argument based
on the extremal statistics of rare regions can be constructed to show that the
low temperature phase is unstable to sequence disorder. We performed a detailed
numerical study of the low temperature phase using the droplet theory as a
guide, and characterized the statistics of large-scale, low-energy excitations
of the secondary structures from the ground state structure. We find the
excitation energy to grow very slowly (i.e., logarithmically) with the length
scale of the excitation, suggesting the existence of a marginal glass phase.
The transition between the low temperature glass phase and the high temperature
molten phase is also characterized numerically. It is revealed by a change in
the coefficient of the logarithmic excitation energy, from being disorder
dominated to entropy dominated.Comment: 24 pages, 16 figure
Turnout and Closeness: Evidence from 60 Years of Bavarian Mayoral Elections
One prediction of the calculus of voting is that electoral closeness positively affects turnout via a higher probability of one vote being decisive. I test this theory with data on all mayoral elections in the German state of Bavaria between 1946 and 2009. Importantly, I use constitutionally prescribed two-round elections to measure electoral closeness and thereby improve on existing work that mostly uses ex- post measures that are prone to endogeneity. The results suggest that electoral closeness matters: A one standard deviation increase in close- ness increases turnout by 1.68 percentage points, which corresponds to 1 6 of a standard deviation in this variable. I also evaluate how other factors like electorate size or rain on election day affect turnout differentially depending on the closeness of the race
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