283 research outputs found
Metal-insulator transition in Ca_{1-x}Li_xPd_3O_4
Metal-insulator transition in Ca_{1-x}Li_xPd_3O_4 has been studied through
charge transport measurements. The resistivity, the Seebeck coefficient, and
the Hall coefficient are consistently explained in terms of a simple one-band
picture, where a hole with a moderately enhanced mass is itinerant
three-dimensionally. Contrary to the theoretical prediction [Phys. Rev. B62,
13426 (2000)], CaPd_3O_4 is unlikely to be an excitonic insulator, and holds a
finite carrier concentration down to 4.2 K. Thus the metal-insulator transition
in this system is basically driven by localization effects.Comment: RevTeX4 format, 4 pages, 5 eps figure
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' — 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
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
Elevated virulence of an emerging viral genotype as a driver of honeybee loss.
PublishedJournal ArticleEmerging infectious diseases (EIDs) have contributed significantly to the current biodiversity crisis, leading to widespread epidemics and population loss. Owing to genetic variation in pathogen virulence, a complete understanding of species decline requires the accurate identification and characterization of EIDs. We explore this issue in the Western honeybee, where increasing mortality of populations in the Northern Hemisphere has caused major concern. Specifically, we investigate the importance of genetic identity of the main suspect in mortality, deformed wing virus (DWV), in driving honeybee loss. Using laboratory experiments and a systematic field survey, we demonstrate that an emerging DWV genotype (DWV-B) is more virulent than the established DWV genotype (DWV-A) and is widespread in the landscape. Furthermore, we show in a simple model that colonies infected with DWV-B collapse sooner than colonies infected with DWV-A. We also identify potential for rapid DWV evolution by revealing extensive genome-wide recombination in vivo The emergence of DWV-B in naive honeybee populations, including via recombination with DWV-A, could be of significant ecological and economic importance. Our findings emphasize that knowledge of pathogen genetic identity and diversity is critical to understanding drivers of species decline.This work was supported by the Federal Ministry of Food,
Agriculture and Consumer Protection (Germany): Fit Bee project
(grant 511-06.01-28-1-71.007-10), the EU: BeeDoc (grant 244956),
iDiv (2013 NGS-Fast Track grant W47004118) and the Insect Pollinators
Initiative (IPI grant BB/I000100/1 and BB/I000151/1). The IPI is
funded jointly by the Biotechnology and Biological Sciences Research
Council, the Department for Environment, Food and Rural Affairs,
the Natural Environment Research Council, the Scottish Government
and the Wellcome Trust, under the Living with Environmental
Change Partnership
Brain transcriptomes of honey bees (Apis mellifera) experimentally infected by two pathogens: Black queen cell virus and Nosema ceranae.
This is the final version of the article. Available from Elsevier via the DOI in this record.Regulation of gene expression in the brain plays an important role in behavioral plasticity and decision making in response to external stimuli. However, both can be severely affected by environmental factors, such as parasites and pathogens. In honey bees, the emergence and re-emergence of pathogens and potential for pathogen co-infection and interaction have been suggested as major components that significantly impaired social behavior and survival. To understand how the honey bee is affected and responds to interacting pathogens, we co-infected workers with two prevalent pathogens of different nature, the positive single strand RNA virus Black queen cell virus (BQCV), and the Microsporidia Nosema ceranae, and explored gene expression changes in brains upon single infections and co-infections. Our data provide an important resource for research on honey bee diseases, and more generally on insect host-pathogen and pathogen-pathogen interactions. Raw and processed data are publicly available in the NCBI/GEO database: (http://www.ncbi.nlm.nih.gov/geo/) under accession number GSE81664.Sequencing was performed thanks to the EU-funded 7th Framework project BEE DOC, Grant Agreement 244956. The authors thank Maureen Labarussias for technical support during bee experiments and preparation for sequencing
Large Thermoelectric Power Factor in TiS2 Crystal with Nearly Stoichiometric Composition
A TiS crystal with a layered structure was found to have a large
thermoelectric power factor.The in-plane power factor at 300 K is
37.1~W/Kcm with resistivity () of 1.7 mcm and
thermopower () of -251~V/K, and this value is comparable to that of the
best thermoelectric material, BiTe alloy. The electrical
resistivity shows both metallic and highly anisotropic behaviors, suggesting
that the electronic structure of this TiS crystal has a
quasi-two-dimensional nature. The large thermoelectric response can be ascribed
to the large density of state just above the Fermi energy and inter-valley
scattering. In spite of the large power factor, the figure of merit, of
TiS is 0.16 at 300 K, because of relatively large thermal conductivity,
68~mW/Kcm. However, most of this value comes from reducible lattice
contribution. Thus, can be improved by reducing lattice thermal
conductivity, e.g., by introducing a rattling unit into the inter-layer sites.Comment: 11 pages, 4 figures, to be published in Physical Review
Wave-dominated siliciclastic and carbonate sedimentation in a Lower Cretaceous lake (Cameros basin, northern Spain)
De acuerdo con los datos estructurales, sedimentológicos y bioestratigráficos disponibles, la cuenca de rift del noreste de Cameros (norte de España) presenta el registro de unos 8000 metros de depósitos de sedimentos continentales de edad Jurásico Superior a Cretácico Inferior, con incursiones menores de origen marino. El propósito del presente trabajo es: (1) documentar la presencia en esta cuenca de las facies carbonatadas y silicicláslicas del Grupo Enciso: (2) proponer un modelo deposicional : y (3) realizar la reconstrucción paleoambiental de un gran sistema lacustre. Nuestro modelo deposicional está basado en la integración de datos cartográfícos con los procedentes del análisis de secciones estratigráficas. A partir del estudio de seis secciones estratigráficas, se han podido identificar tres asociaciones de facies diferentes, reconocidas a su vez en otros afloramientos del Grupo Enciso. Estas asociaciones de facies son: 1) asociación de facies de ambiente lacustre abierto 2) asociación de facies de ambiente lacustre marginal siliciclástico (canal distributario, barra de desembocadura pantanosas de shoreface Iake fringin ) y 3 ambiente 1acustre marginal de facies carbonatada (asociaciones de facies palustres dominadas por tormentas y lacustre abierta con desecación. A lo largo del tiempo se alternan dos tipos de margen 1acustre: uno silicicrástico, dominado por la acción del oleaje, y otro carbonatado según un modelo de rampa suavemente inclinada. Se sugiere que el establecimiento de estos dos tipos de depósitos lacustres estuvo controlada por factores climáticos
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
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
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