1,107 research outputs found
Effects of obesity, total fasting and realimentation on L-thyroxine (T4), 3,5,3', - L-triiodothyronine (T3), - 3,3',5'-L-triiodorhyronine (rT3), - thyroxine binding globulin (TBG), cortisol, thyrotophin, cortisol-binding globulin (CBG), transferrin, alpha2-haptoglobin and complement C 3 in serum
Realization of a superconducting atom chip
We have trapped rubidium atoms in the magnetic field produced by a
superconducting atom chip operated at liquid Helium temperatures. Up to
atoms are held in a Ioffe-Pritchard trap at a distance of 440
m from the chip surface, with a temperature of 40 K. The trap
lifetime reaches 115 s at low atomic densities. These results open the way to
the exploration of atom--surface interactions and coherent atomic transport in
a superconducting environment, whose properties are radically different from
normal metals at room temperature.Comment: Submitted to Phys. Rev. Let
A Heterosynaptic Learning Rule for Neural Networks
In this article we intoduce a novel stochastic Hebb-like learning rule for
neural networks that is neurobiologically motivated. This learning rule
combines features of unsupervised (Hebbian) and supervised (reinforcement)
learning and is stochastic with respect to the selection of the time points
when a synapse is modified. Moreover, the learning rule does not only affect
the synapse between pre- and postsynaptic neuron, which is called homosynaptic
plasticity, but effects also further remote synapses of the pre- and
postsynaptic neuron. This more complex form of synaptic plasticity has recently
come under investigations in neurobiology and is called heterosynaptic
plasticity. We demonstrate that this learning rule is useful in training neural
networks by learning parity functions including the exclusive-or (XOR) mapping
in a multilayer feed-forward network. We find, that our stochastic learning
rule works well, even in the presence of noise. Importantly, the mean learning
time increases with the number of patterns to be learned polynomially,
indicating efficient learning.Comment: 19 page
High-resolution spatial mapping of a superconducting NbN wire using single-electron detection
Superconducting NbN wires have recently received attention as detectors for
visible and infrared photons. We present experiments in which we use a NbN wire
for high-efficiency (40 %) detection of single electrons with keV energy. We
use the beam of a scanning electron microscope as a focussed, stable, and
calibrated electron source. Scanning the beam over the surface of the wire
provides a map of the detection efficiency. This map shows features as small as
150 nm, revealing wire inhomogeneities. The intrinsic resolution of this
mapping method, superior to optical methods, provides the basis of a
characterization tool relevant for photon detectors.Comment: 2009 IEEE Toronto International Conference, Science and Technology
for Humanity (TIC-STH
DWM07 global empirical model of upper thermospheric storm-induced disturbance winds
We present a global empirical disturbance wind model (DWM07) that represents average geospace-storm-induced perturbations of upper thermospheric (200-600 km altitude) neutral winds. DWM07 depends on the following three parameters: magnetic latitude, magnetic local time, and the 3-h Kp geomagnetic activity index. The latitude and local time dependences are represented by vector spherical harmonic functions ( up to degree 10 in latitude and order 3 in local time), and the Kp dependence is represented by quadratic B-splines. DWM07 is the storm time thermospheric component of the new Horizontal Wind Model (HWM07), which is described in a companion paper. DWM07 is based on data from the Wind Imaging Interferometer on board the Upper Atmosphere Research Satellite, the Wind and Temperature Spectrometer on board Dynamics Explorer 2, and seven ground-based Fabry-Perot interferometers. The perturbation winds derived from the three data sets are in good mutual agreement under most conditions, and the model captures most of the climatological variations evident in the data
Viral expression and molecular profiling in liver tissue versus microdissected hepatocytes in hepatitis B virus - associated hepatocellular carcinoma.
Background: The molecular mechanisms whereby hepatitis B virus (HBV) induces hepatocellular carcinoma (HCC)
remain elusive. We used genomic and molecular techniques to investigate host-virus interactions by studying multiple areas of the same liver from patients with HCC.
Methods: We compared the gene signature of whole liver tissue (WLT) versus laser capture-microdissected (LCM)
hepatocytes along with the intrahepatic expression of HBV. Gene expression profiling was performed on up to 17 WLT specimens obtained at various distances from the tumor center from individual livers of 11 patients with HCC and on selected LCM samples. HBV markers in liver and serum were determined by real-time polymerase chain reaction (PCR)and confocal immunofluorescence.
Results: Analysis of 5 areas of the liver showed a sharp change in gene expression between the immediate perilesional area and tumor periphery that correlated with a significant decrease in the intrahepatic expression of HB surface antigen (HBsAg). The tumor was characterized by a large preponderance of down-regulated genes, mostly involved in the
metabolism of lipids and fatty acids, glucose, amino acids and drugs, with down-regulation of pathways involved in the activation of PXR/RXR and PPARα/RXRα nuclear receptors, comprising PGC-1α and FOXO1, two key regulators
critically involved not only in the metabolic functions of the liver but also in the life cycle of HBV, acting as essential transcription factors for viral gene expression. These findings were confirmed by gene expression of microdissected
hepatocytes. Moreover, LCM of malignant hepatocytes also revealed up-regulation of unique genes associated with
cancer and signaling Pathways, including two novel HCC-associated cancer testis antigen genes, NUF2 and TTK.
Conclusions: Integrated gene expression profiling of whole liver tissue with that of microdissected hepatocytes
demonstrated that HBV-associated HCC is characterized by a metabolism switch-off and by a significant reduction in
HBsAg. LCM proved to be a critical tool to validate gene signatures associated with HCC and to identify genes that may play a role in hepatocarcinogenesis, opening new perspectives for the discovery of novel diagnostic markers and therapeutic targets
Transapical aortic implantation of autologous marrow stromal cell-based tissue-engineered heart valves: first experiences in the systemic circulation
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Emerging pattern of global change in the upper atmosphere and ionosphere
In the upper atmosphere, greenhouse gases produce a cooling effect, instead of a warming effect. Increases in greenhouse gas concentrations are expected to induce substantial changes in the mesosphere, thermosphere, and ionosphere, including a thermal contraction of these layers. In this article we construct for the first time a pattern of the observed long-term global change in the upper atmosphere, based on trend studies of various parameters. The picture we obtain is qualitative, and contains several gaps and a few discrepancies, but the overall pattern of observed long-term changes throughout the upper atmosphere is consistent with model predictions of the effect of greenhouse gas increases. Together with the large body of lower atmospheric trend research, our synthesis indicates that anthropogenic emissions of greenhouse gases are affecting the atmosphere at nearly all altitudes between ground and space
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