1,092 research outputs found
Controlled Flooding with Passive Anti-Flooding for Urgent Messages in Body Area Sensor Networks
Hysteresis-Free Nanosecond Pulsed Electrical Characterization of Top-Gated Graphene Transistors
We measure top-gated graphene field effect transistors (GFETs) with
nanosecond-range pulsed gate and drain voltages. Due to high-k dielectric or
graphene imperfections, the drain current decreases ~10% over time scales of
~10 us, consistent with charge trapping mechanisms. Pulsed operation leads to
hysteresis-free I-V characteristics, which are studied with pulses as short as
75 ns and 150 ns at the drain and gate, respectively. The pulsed operation
enables reliable extraction of GFET intrinsic transconductance and mobility
values independent of sweep direction, which are up to a factor of two higher
than those obtained from simple DC characterization. We also observe
drain-bias-induced charge trapping effects at lateral fields greater than 0.1
V/um. In addition, using modeling and capacitance-voltage measurements we
extract charge trap densities up to 10^12 1/cm^2 in the top gate dielectric
(here Al2O3). Our study illustrates important time- and field-dependent
imperfections of top-gated GFETs with high-k dielectrics, which must be
carefully considered for future developments of this technologyComment: to appear in IEEE Transactions on Electron Devices (2014
Funcionamiento del riego particular en los Andes ecuatorianos : recomendaciones para el Plan Nacional de Regio = Fonctionnement de l'irrigation traditionnelle dans les Andes équatoriennes : recommandations pour le Plan National d'Irrigation
Quaternionic and Octonionic Spinors. A Classification
Quaternionic and octonionic realizations of Clifford algebras and spinors are
classified and explicitly constructed in terms of recursive formulas. The most
general free dynamics in arbitrary signature space-times for both quaternionic
and octonionic spinors is presented. In the octonionic case we further provide
a systematic list of results and tables expressing, e.g., the relations of the
octonionic Clifford algebras with the cosets over the Lorentz algebras,
the identities satisfied by the higher-rank antisymmetric octonionic tensors
and so on. Applications of these results range from the classification of
octonionic generalized supersymmetries, the construction of octonionic
superstrings, as well as the investigations concerning the recently discovered
octonionic -superalgebra and its superconformal extension.Comment: 24 pages, LaTe
Mechanical Strength of 17 134 Model Proteins and Cysteine Slipknots
A new theoretical survey of proteins' resistance to constant speed stretching
is performed for a set of 17 134 proteins as described by a structure-based
model. The proteins selected have no gaps in their structure determination and
consist of no more than 250 amino acids. Our previous studies have dealt with
7510 proteins of no more than 150 amino acids. The proteins are ranked
according to the strength of the resistance. Most of the predicted top-strength
proteins have not yet been studied experimentally. Architectures and folds
which are likely to yield large forces are identified. New types of potent
force clamps are discovered. They involve disulphide bridges and, in
particular, cysteine slipknots. An effective energy parameter of the model is
estimated by comparing the theoretical data on characteristic forces to the
corresponding experimental values combined with an extrapolation of the
theoretical data to the experimental pulling speeds. These studies provide
guidance for future experiments on single molecule manipulation and should lead
to selection of proteins for applications. A new class of proteins, involving
cystein slipknots, is identified as one that is expected to lead to the
strongest force clamps known. This class is characterized through molecular
dynamics simulations.Comment: 40 pages, 13 PostScript figure
Extracellular cold inducible RNA-binding protein mediates binge alcohol-induced brain hypoactivity and impaired cognition in mice
Optimum spectral window for imaging of art with optical coherence tomography
Optical Coherence Tomography (OCT) has been shown to have potential for important applications in the field of art conservation and archaeology due to its ability to image subsurface microstructures non-invasively. However, its depth of penetration in painted objects is limited due to the strong scattering properties of artists’ paints. VIS-NIR (400 nm – 2400 nm) reflectance spectra of a wide variety of paints made with historic artists’ pigments have been measured. The best spectral window with which to use optical coherence tomography (OCT) for the imaging of subsurface structure of paintings was found to be around 2.2 μm. The same spectral window would also be most suitable for direct infrared imaging of preparatory sketches under the paint layers. The reflectance spectra from a large sample of chemically verified pigments provide information on the spectral transparency of historic artists’ pigments/paints as well as a reference set of spectra for pigment identification. The results of the paper suggest that broadband sources at ~2 microns are highly desirable for OCT applications in art and potentially material science in general
Brenneria quercina and Serratia spp. isolated from Spanish oak trees: molecular characterization and PCR development
Brenneria quercina has been reported as one of the causal agents of oak decline in Spain. To investigate the bacterial variability of this pathogen from different Spanish oak forests, a collection of 38 bacterial isolates from seven geographic locations and from different oak species was analysed by sequencing 16S rDNA and rep-PCR fingerprinting. All Spanish isolates of B. quercina were grouped by rep-PCR into a homogenous cluster that differed significantly from B. quercina reference strains from California. 16S rDNA analysis revealed that 34 out of 38 isolates were Brenneria . However, four isolates belonged to the genus Serratia , suggesting that this bacterium could cause cankers in oak trees. The information obtained by rep-PCR fingerprint analysis was used to develop PCR primers for the sensitive and specific detection of B. quercina from infected plant tissues. Pathogenicity tests performed with Brenneria and Serratia isolates showed that both were able to grow and cause cankers in oak trees
Deconvolution of dynamic mechanical networks
Time-resolved single-molecule biophysical experiments yield data that contain
a wealth of dynamic information, in addition to the equilibrium distributions
derived from histograms of the time series. In typical force spectroscopic
setups the molecule is connected via linkers to a read-out device, forming a
mechanically coupled dynamic network. Deconvolution of equilibrium
distributions, filtering out the influence of the linkers, is a straightforward
and common practice. We have developed an analogous dynamic deconvolution
theory for the more challenging task of extracting kinetic properties of
individual components in networks of arbitrary complexity and topology. Our
method determines the intrinsic linear response functions of a given molecule
in the network, describing the power spectrum of conformational fluctuations.
The practicality of our approach is demonstrated for the particular case of a
protein linked via DNA handles to two optically trapped beads at constant
stretching force, which we mimic through Brownian dynamics simulations. Each
well in the protein free energy landscape (corresponding to folded, unfolded,
or possibly intermediate states) will have its own characteristic equilibrium
fluctuations. The associated linear response function is rich in physical
content, since it depends both on the shape of the well and its diffusivity---a
measure of the internal friction arising from such processes like the transient
breaking and reformation of bonds in the protein structure. Starting from the
autocorrelation functions of the equilibrium bead fluctuations measured in this
force clamp setup, we show how an experimentalist can accurately extract the
state-dependent protein diffusivity using a straightforward two-step procedure.Comment: 9 pages, 3 figures + supplementary material 14 pages, 4 figure
Cerebello-thalamo-cortical hyperconnectivity as a state-independent functional neural signature for psychosis prediction and characterization
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