285 research outputs found
Interactions of hadrons in the CALICE SiW ECAL prototype
This article presents results of test beams obtained for pions with energies between 2 and 10 GeV which interact in the volume of the highly granular CALICE Silicon-Tungsten electromagnetic calorimeter prototype (SiW ECAL). An algorithm optimised to ïŹnd interactions in the SiW ECAL at small hadron energies is developed. This allows identifying the interaction point in the calorimeter at an efficiency between 62% and 83% depending on the energy of the primary particle. The unprecedented granularity of the SiW ECAL allows for the distinction between different interaction types. This in turn permits more detailed examinations of hadronic models than was possible with traditional calorimeters. So far, it is possible to disentangle minimum ionising particle (MIP) events, elastic Ï-nucleus scattering and spallation reactions which lead to the start of a internuclear cascade or which result in a small number of highly ionising particles. Various observables are compared with predictions from hadronic physics lists as contained in the simulation toolkit geant4
Party finance reform as constitutional engineering? The effectiveness and unintended consequences of party finance reform in France and Britain
In both Britain and France, party funding was traditionally characterized by a laissez faire approach and a conspicuous lack of regulation. In France, this was tantamount to a 'legislative vacuum'. In the last two decades, however, both countries have sought to fundamentally reform their political finance regulation regimes. This prompted, in Britain, the Political Parties, Elections and Referendums Act 2000, and in France a bout of 'legislative incontinence' â profoundly transforming the political finance regime between 1988 and 1995. This article seeks to explore and compare the impacts of the reforms in each country in a bid to explain the unintended consequences of the alternative paths taken and the effectiveness of the new party finance regime in each country. It finds that constitutional engineering through party finance reform is a singularly inexact science, largely due to the imperfect nature of information, the limited predictability of cause and effect, and the constraining influence of non-party actors, such as the Constitutional Council in France, and the Electoral Commission in Britain
Unexpected band gap increase in the Fe2VAl Heusler compound
Knowing the electronic structure of a material is essential in energy
applications to rationalize its performance and propose alternatives. Materials
for thermoelectric applications are generally small-gap semiconductors and
should have a high figure of merit ZT. Even if the Fe2VAl Heusler compound has
a decent ZT, its conductive nature (semi-metal or semiconductor) is not yet
clarified especially at low temperature. In this paper, we focus our DFT
calculations on the effect of temperature on the bandgap of Fe2VAl. In contrast
to what is usually observed, we show that both the temperature increase and the
formation of thermally-activated Al/V inversion defects (observed
experimentally), open the bandgap. Such an unusual behavior is the key for
reconciling all bandgap measurements performed on the Fe2VAl compound using a
standard GGA functional and could be an efficient way for improving the
thermoelectric properties of this family of materials.Comment: 10 pages, 5 figure
A precise characterisation of the top quark electro-weak vertices at the ILC
Top quark production in the process at a future linear
electron positron collider with polarised beams is a powerful tool to determine
indirectly the scale of new physics. The presented study, based on a detailed
simulation of the ILD detector concept, assumes a centre-of-mass energy of
GeV and a luminosity of
equally shared between the incoming beam polarisations of . Events are selected in which the top pair
decays semi-leptonically and the cross sections and the forward-backward
asymmetries are determined. Based on these results, the vector, axial vector
and tensorial conserving couplings are extracted separately for the photon
and the component. With the expected precision, a large number of models
in which the top quark acts as a messenger to new physics can be distinguished
with many standard deviations. This will dramatically improve expectations from
e.g. the LHC for electro-weak couplings of the top quark.Comment: This work is an update of arXiv:1307.8102, minor changes w.r.t. v1
(typos, wrong grammar, incomplete sentences etc.
Leading interactions in the - compound
The present study shows that the electronic structure of the
- family of compounds () is based on
weakly interacting two-leg ladders, in contrast with the zig-zag chain model
one could expect from their crystal structure. Spin dimer analysis, based on
extended H\"{u}ckel tight-binding calculations, was performed to determine the
structure of the dominant transfer and magnetic interactions in the room
temperature - phase. Two different two-legs ladders,
associated with different charge/spin orders are proposed to describe these
one-dimensional -type systems. The antiferromagnetic ladders are packed
in an 'IPN' geometry and coupled to each other through weak antiferromagnetic
interactions. This arrangement of the dominant interactions explains the
otherwise surprising similarities of the optical conductivity and Raman spectra
for the one-dimensional -type phases and the two-dimensional
-type ones such as the well-known - system
The virulent, emerging genotype B of Deformed wing virus is closely linked to overwinter honeybee worker loss
Bees are considered to be threatened globally, with severe overwinter losses
of the most important commercial pollinator, the Western honeybee, a major
concern in the Northern Hemisphere. Emerging infectious diseases have risen to
prominence due to their temporal correlation with colony losses. Among these
is Deformed wing virus (DWV), which has been frequently linked to colony
mortality. We now provide evidence of a strong statistical association between
overwintering colony decline in the field and the presence of DWV genotype-B
(DWV-B), a genetic variant of DWV that has recently been shown to be more
virulent than the original DWV genotype-A. We link the prevalence of DWV-B
directly to a quantitative measure of overwinter decline (workforce mortality)
of honeybee colonies in the field. We demonstrate that increased prevalence of
virus infection in individual bees is associated with higher overwinter
mortality. We also observed a substantial reduction of infected colonies in
the spring, suggesting that virus-infected individuals had died during the
winter. Our findings demonstrate that DWV-B, plus possible A/B recombinants
exhibiting DWV-B at PCR primer binding sites, may be a major cause of elevated
overwinter honeybee loss. Its potential emergence in naĂŻve populations of bees
may have far-reaching ecological and economic impacts
Stability, Entrapment and Variant Formation of Salmonella Genomic Island 1
<div><h3>Background</h3><p>The <em>Salmonella</em> genomic island 1 (SGI1) is a 42.4 kb integrative mobilizable element containing several antibiotic resistance determinants embedded in a complex integron segment In104. The numerous SGI1 variants identified so far, differ mainly in this segment and the explanations of their emergence were mostly based on comparative structure analyses. Here we provide experimental studies on the stability, entrapment and variant formation of this peculiar gene cluster originally found in <em>S</em>. Typhimurium.</p> <h3>Methodology/Principal Findings</h3><p>Segregation and conjugation tests and various molecular techniques were used to detect the emerging SGI1 variants in <em>Salmonella</em> populations of 17 <em>Salmonella enterica</em> serovar Typhimurium DT104 isolates from Hungary. The SGI1s in these isolates proved to be fully competent in excision, conjugal transfer by the IncA/C helper plasmid R55, and integration into the <em>E. coli</em> chromosome. A trap vector has been constructed and successfully applied to capture the island on a plasmid. Monitoring of segregation of SGI1 indicated high stability of the island. SGI1-free segregants did not accumulate during long-term propagation, but several SGI1 variants could be obtained. Most of them appeared to be identical to SGI1-B and SGI1-C, but two new variants caused by deletions via a short-homology-dependent recombination process have also been detected. We have also noticed that the presence of the conjugation helper plasmid increased the formation of these deletion variants considerably.</p> <h3>Conclusions/Significance</h3><p>Despite that excision of SGI1 from the chromosome was proven in SGI1<sup>+</sup><em>Salmonella</em> populations, its complete loss could not be observed. On the other hand, we demonstrated that several variants, among them two newly identified ones, arose with detectable frequencies in these populations in a short timescale and their formation was promoted by the helper plasmid. This reflects that IncA/C helper plasmids are not only involved in the horizontal spreading of SGI1, but may also contribute to its evolution.</p> </div
honeybee workers exhibit conserved molecular responses to diverse pathogens
Background Organisms typically face infection by diverse pathogens, and hosts
are thought to have developed specific responses to each type of pathogen they
encounter. The advent of transcriptomics now makes it possible to test this
hypothesis and compare host gene expression responses to multiple pathogens at
a genome-wide scale. Here, we performed a meta-analysis of multiple published
and new transcriptomes using a newly developed bioinformatics approach that
filters genes based on their expression profile across datasets. Thereby, we
identified common and unique molecular responses of a model host species, the
honey bee (Apis mellifera), to its major pathogens and parasites: the
Microsporidia Nosema apis and Nosema ceranae, RNA viruses, and the
ectoparasitic mite Varroa destructor, which transmits viruses. Results We
identified a common suite of genes and conserved molecular pathways that
respond to all investigated pathogens, a result that suggests a commonality in
response mechanisms to diverse pathogens. We found that genes differentially
expressed after infection exhibit a higher evolutionary rate than non-
differentially expressed genes. Using our new bioinformatics approach, we
unveiled additional pathogen-specific responses of honey bees; we found that
apoptosis appeared to be an important response following microsporidian
infection, while genes from the immune signalling pathways, Toll and Imd, were
differentially expressed after Varroa/virus infection. Finally, we applied our
bioinformatics approach and generated a gene co-expression network to identify
highly connected (hub) genes that may represent important mediators and
regulators of anti-pathogen responses. Conclusions Our meta-analysis generated
a comprehensive overview of the host metabolic and other biological processes
that mediate interactions between insects and their pathogens. We identified
key host genes and pathways that respond to phylogenetically diverse
pathogens, representing an important source for future functional studies as
well as offering new routes to identify or generate pathogen resilient honey
bee stocks. The statistical and bioinformatics approaches that were developed
for this study are broadly applicable to synthesize information across
transcriptomic datasets. These approaches will likely have utility in
addressing a variety of biological questions
In vivo recordings of brain activity using organic transistors.
In vivo electrophysiological recordings of neuronal circuits are necessary for diagnostic purposes and for brain-machine interfaces. Organic electronic devices constitute a promising candidate because of their mechanical flexibility and biocompatibility. Here we demonstrate the engineering of an organic electrochemical transistor embedded in an ultrathin organic film designed to record electrophysiological signals on the surface of the brain. The device, tested in vivo on epileptiform discharges, displayed superior signal-to-noise ratio due to local amplification compared with surface electrodes. The organic transistor was able to record on the surface low-amplitude brain activities, which were poorly resolved with surface electrodes. This study introduces a new class of biocompatible, highly flexible devices for recording brain activity with superior signal-to-noise ratio that hold great promise for medical applications
Widespread Wolbachia infection in terrestrial isopods and other crustaceans
Wolbachia bacteria are obligate intracellular alpha-Proteobacteria of arthropods and nematodes. Although widespread among isopod crustaceans, they have seldom been found in non-isopod crustacean species. Here, we report Wolbachia infection in fourteen new crustacean species. Our results extend the range of Wolbachia infections in terrestrial isopods and amphipods (class Malacostraca). We report the occurrence of two different Wolbachia strains in two host species (a terrestrial isopod and an amphipod). Moreover, the discovery of Wolbachia in the goose barnacle Lepas anatifera (subclass Thecostraca) establishes Wolbachia infection in class Maxillopoda. The new bacterial strains are closely related to B-supergroup Wolbachia strains previously reported from crustacean hosts. Our results suggest that Wolbachia infection may be much more widespread in crustaceans than previously thought. The presence of related Wolbachia strains in highly divergent crustacean hosts suggests that Wolbachia endosymbionts can naturally adapt to a wide range of crustacean hosts. Given the ability of isopod Wolbachia strains to induce feminization of genetic males or cytoplasmic incompatibility, we speculate that manipulation of crustacean-borne Wolbachia bacteria might represent potential tools for controlling crustacean species of commercial interest and crustacean or insect disease vectors.This research was funded by a European Research Council Starting Grant (FP7/2007-2013 grant 260729 EndoSexDet) to RC and a Comité Mixte de Coopération Universitaire Franco-Tunisien grant to DB and FCC
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