660 research outputs found
Deciphering the Link between Doubly Uniparental Inheritance of mtDNA and Sex Determination in Bivalves: Clues from Comparative Transcriptomics
Bivalves exhibit an astonishing diversity of sexual systems and sex-determining mechanisms. They can be gonochoric, hermaphroditic or androgenetic, with both genetic and environmental factors known to determine or influence sex. One unique sex-determining system involving the mitochondrial genome has also been hypothesized to exist in bivalves with doubly uniparental inheritance (DUI) of mtDNA. However, the link between DUI and sex determination remains obscure. In this study, we performed a comparative gonad transcriptomics analysis for two DUI-possessing freshwater mussel species to better understand the mechanisms underlying sex determination and DUI in these bivalves. We used a BLAST reciprocal analysis to identify orthologs between Venustaconcha ellipsiformis and Utterbackia peninsularis and compared our results with previously published sex-specific bivalve transcriptomes to identify conserved sex-determining genes. We also compared our data with other DUI species to identify candidate genes possibly involved in the regulation of DUI. A total of 3c12,000 orthologous relationships were found, with 2,583 genes differentially expressed in both species. Among these genes, key sex-determining factors previously reported in vertebrates and in bivalves (e.g., Sry, Dmrt1, Foxl2) were identified, suggesting that some steps of the sex-determination pathway may be deeply conserved in metazoans. Our results also support the hypothesis that a modified ubiquitination mechanism could be responsible for the retention of the paternal mtDNA in male bivalves, and revealed that DNA methylation could also be involved in the regulation of DUI. Globally, our results suggest that sets of genes associated with sex determination and DUI are similar in distantly-related DUI species
Seebeck Effect in Magnetic Tunnel Junctions
Creating temperature gradients in magnetic nanostructures has resulted in a
new research direction, i.e., the combination of magneto- and thermoelectric
effects. Here, we demonstrate the observation of one important effect of this
class: the magneto-Seebeck effect. It is observed when a magnetic configuration
changes the charge based Seebeck coefficient. In particular, the Seebeck
coefficient changes during the transition from a parallel to an antiparallel
magnetic configuration in a tunnel junction. In that respect, it is the analog
to the tunneling magnetoresistance. The Seebeck coefficients in parallel and
antiparallel configuration are in the order of the voltages known from the
charge-Seebeck effect. The size and sign of the effect can be controlled by the
composition of the electrodes' atomic layers adjacent to the barrier and the
temperature. Experimentally, we realized 8.8 % magneto-Seebeck effect, which
results from a voltage change of about -8.7 {\mu}V/K from the antiparallel to
the parallel direction close to the predicted value of -12.1 {\mu}V/K.Comment: 16 pages, 7 figures, 2 table
Stress response inside perturbed particle assemblies
The effect of structural disorder on the stress response inside three
dimensional particle assemblies is studied using computer simulations of
frictionless sphere packings. Upon applying a localised, perturbative force
within the packings, the resulting {\it Green's} function response is mapped
inside the different assemblies, thus providing an explicit view as to how the
imposed perturbation is transmitted through the packing. In weakly disordered
arrays, the resulting transmission of forces is of the double-peak variety, but
with peak widths scaling linearly with distance from the source of the
perturbation. This behaviour is consistent with an anisotropic elasticity
response profile. Increasing the disorder distorts the response function until
a single-peak response is obtained for fully disordered packings consistent
with an isotropic description.Comment: 8 pages, 7 figure captions To appear in Granular Matte
Giant thermoelectric effect in Al2O3 magnetic tunnel junctions
Thermoelectric effects in magnetic nanostructures and the so-called spin
caloritronics are attracting much interest. Indeed it provides a new way to
control and manipulate spin currents which are key elements of spin-based
electronics. Here we report on giant magnetothermoelectric effect in Al2O3
magnetic tunnel junctions. The thermovoltage in this geometry can reach 1 mV.
Moreover a magneto-thermovoltage effect could be measured with ratio similar to
the tunnel magnetoresistance ratio. The Seebeck coefficient can then be tuned
by changing the relative magnetization orientation of the two magnetic layers
in the tunnel junction. Therefore our experiments extend the range of
spintronic devices application to thermoelectricity and provide a crucial piece
of information for understanding the physics of thermal spin transport.Comment: 9 pages, 7 figures, added reference
Precision Determination of the Neutron Spin Structure Function g1n
We report on a precision measurement of the neutron spin structure function
using deep inelastic scattering of polarized electrons by polarized
^3He. For the kinematic range 0.014<x<0.7 and 1 (GeV/c)^2< Q^2< 17 (GeV/c)^2,
we obtain at an average . We find relatively large negative
values for at low . The results call into question the usual Regge
theory method for extrapolating to x=0 to find the full neutron integral
, needed for testing quark-parton model and QCD sum rules.Comment: 5 pages, 3 figures To be published in Phys. Rev. Let
Neurogenesis Drives Stimulus Decorrelation in a Model of the Olfactory Bulb
The reshaping and decorrelation of similar activity patterns by neuronal
networks can enhance their discriminability, storage, and retrieval. How can
such networks learn to decorrelate new complex patterns, as they arise in the
olfactory system? Using a computational network model for the dominant neural
populations of the olfactory bulb we show that fundamental aspects of the adult
neurogenesis observed in the olfactory bulb -- the persistent addition of new
inhibitory granule cells to the network, their activity-dependent survival, and
the reciprocal character of their synapses with the principal mitral cells --
are sufficient to restructure the network and to alter its encoding of odor
stimuli adaptively so as to reduce the correlations between the bulbar
representations of similar stimuli. The decorrelation is quite robust with
respect to various types of perturbations of the reciprocity. The model
parsimoniously captures the experimentally observed role of neurogenesis in
perceptual learning and the enhanced response of young granule cells to novel
stimuli. Moreover, it makes specific predictions for the type of odor
enrichment that should be effective in enhancing the ability of animals to
discriminate similar odor mixtures
Smart Mobility Blueprint for Illinois
R27-228Connected, automated, shared, and electric (CASE) technologies have invoked Mobility 4.0\u2014a connected, digitized, multimodal, and autonomous system of systems. This project established a flexible and adaptable blueprint that would streamline multidisciplinary and multistakeholder efforts as well as leverage available resources to prepare the Illinois Department of Transportation and other transportation agencies. Illinois has several strengths that make it an attractive location for CASE technology companies, including a talent pool from top-ranked universities, well-developed transportation infrastructure, government support, and a robust ecosystem of collaboration and innovation. Illinois also faces potential challenges (e.g., competition from other states and countries, limited access to funding, regulatory hurdles, and infrastructure readiness for new mobility technologies). Seven smart mobility pillars were identified in this study for Illinois\u2014namely, connected and automated (CA) freight, scaling intelligent transportation systems, farm automation, insurance, urban mobility, CA logistics, and alternative fuels. The balanced scorecard ranked the pillars as follows (from highest): alternative fuels, scaling intelligent transportation systems, CA freight, farm automation, CA logistics, insurance, and urban mobility. Tactical focus areas were also identified per pillar and were prioritized with suggested leads and stakeholders to champion the CASE directives and opportunities. Near-term actions for Illinois were also suggested that included establishing a central structure for Illinois\u2019 CASE program, enriching the knowledge base and experience, preparing transportation infrastructure, partnerships with external stakeholders, and expansion of laws, regulations, and policies that will help administer and grow CASE technology deployment and integration
Measurement of the Proton and Deuteron Spin Structure Function g_1 in the Resonance Region
We have measured the proton and deuteron spin structure functions g_1^p and
g_1^d in the region of the nucleon resonances for W^2 < 5 GeV^2 and and GeV^2 by inelastically scattering 9.7 GeV polarized
electrons off polarized and targets. We observe
significant structure in g_1^p in the resonance region. We have used the
present results, together with the deep-inelastic data at higher W^2, to
extract . This is the first
information on the low-Q^2 evolution of Gamma toward the Gerasimov-Drell-Hearn
limit at Q^2 = 0.Comment: 7 pages, 2 figure
Spin Caloritronics
This is a brief overview of the state of the art of spin caloritronics, the
science and technology of controlling heat currents by the electron spin degree
of freedom (and vice versa).Comment: To be published in "Spin Current", edited by S. Maekawa, E. Saitoh,
S. Valenzuela and Y. Kimura, Oxford University Pres
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