264 research outputs found
Comparison of FDTD computed and measured radiation patterns of commercial mobile telephones in presence of the human head
Journal ArticleIn this letter, finite-difference time-domain (FDTD) computed radiation patterns of mobile telephones are carefully compared with those measured in our laboratory. The question on the capability of the FDTD method to correctly predict the radiated electromagnetic fields of today's structurally complex mobile telephones is addressed. Two commercially available cellular telephones equipped with two different antennas (one helix and one helix monopole) have been considered and the radiation patterns have been measured and FDTD computed with and without the human head. The FDTD computed and measured radiation patterns show good agreement. This verifies that numerical techniques are suitable for accurately modeling radiation patterns of realistic cellular telephones and, more importantly, that the FDTD method is a valid alternative to measurements in the design of new cellular telephones
Charge Offset Stability in Si Single Electron Devices with Al Gates
We report on the charge offset drift (time stability) in Si single electron
devices (SEDs) defined with aluminum (Al) gates. The size of the charge offset
drift (0.15 ) is intermediate between that of Al/AlO/Al tunnel junctions
(greater than 1 ) and Si SEDs defined with Si gates (0.01 ). This range
of values suggests that defects in the AlO are the main cause of the charge
offset drift instability
Enabling Micro-level Demand-Side Grid Flexiblity in Resource Constrained Environments
The increased penetration of uncertain and variable renewable energy presents
various resource and operational electric grid challenges. Micro-level
(household and small commercial) demand-side grid flexibility could be a
cost-effective strategy to integrate high penetrations of wind and solar
energy, but literature and field deployments exploring the necessary
information and communication technologies (ICTs) are scant. This paper
presents an exploratory framework for enabling information driven grid
flexibility through the Internet of Things (IoT), and a proof-of-concept
wireless sensor gateway (FlexBox) to collect the necessary parameters for
adequately monitoring and actuating the micro-level demand-side. In the summer
of 2015, thirty sensor gateways were deployed in the city of Managua
(Nicaragua) to develop a baseline for a near future small-scale demand response
pilot implementation. FlexBox field data has begun shedding light on
relationships between ambient temperature and load energy consumption, load and
building envelope energy efficiency challenges, latency communication network
challenges, and opportunities to engage existing demand-side user behavioral
patterns. Information driven grid flexibility strategies present great
opportunity to develop new technologies, system architectures, and
implementation approaches that can easily scale across regions, incomes, and
levels of development
Overlapping-gate architecture for silicon Hall bar MOSFET devices in the low electron density regime
We report the fabrication and study of Hall bar MOSFET devices in which an
overlapping-gate architecture allows four-terminal measurements of low-density
2D electron systems, while maintaining a high density at the ohmic contacts.
Comparison with devices made using a standard single gate show that
measurements can be performed at much lower densities and higher channel
resistances, despite a reduced peak mobility. We also observe a voltage
threshold shift which we attribute to negative oxide charge, injected during
electron-beam lithography processing.Comment: 4 pages, 4 figures, submitted for Applied Physics Letter
Altered gene expression changes in Arabidopsis leaf tissues and protoplasts in response to Plum pox virus infection
<p>Abstract</p> <p>Background</p> <p>Virus infection induces the activation and suppression of global gene expression in the host. Profiling gene expression changes in the host may provide insights into the molecular mechanisms that underlie host physiological and phenotypic responses to virus infection. In this study, the <it>Arabidopsis </it>Affymetrix ATH1 array was used to assess global gene expression changes in <it>Arabidopsis thaliana </it>plants infected with <it>Plum pox virus </it>(PPV). To identify early genes in response to PPV infection, an <it>Arabidopsis </it>synchronized single-cell transformation system was developed. <it>Arabidopsis </it>protoplasts were transfected with a PPV infectious clone and global gene expression changes in the transfected protoplasts were profiled.</p> <p>Results</p> <p>Microarray analysis of PPV-infected <it>Arabidopsis </it>leaf tissues identified 2013 and 1457 genes that were significantly (<it>Q </it>≤ 0.05) up- (≥ 2.5 fold) and downregulated (≤ -2.5 fold), respectively. Genes associated with soluble sugar, starch and amino acid, intracellular membrane/membrane-bound organelles, chloroplast, and protein fate were upregulated, while genes related to development/storage proteins, protein synthesis and translation, and cell wall-associated components were downregulated. These gene expression changes were associated with PPV infection and symptom development. Further transcriptional profiling of protoplasts transfected with a PPV infectious clone revealed the upregulation of defence and cellular signalling genes as early as 6 hours post transfection. A cross sequence comparison analysis of genes differentially regulated by PPV-infected <it>Arabidopsis </it>leaves against uniEST sequences derived from PPV-infected leaves of <it>Prunus persica</it>, a natural host of PPV, identified orthologs related to defence, metabolism and protein synthesis. The cross comparison of genes differentially regulated by PPV infection and by the infections of other positive sense RNA viruses revealed a common set of 416 genes. These identified genes, particularly the early responsive genes, may be critical in virus infection.</p> <p>Conclusion</p> <p>Gene expression changes in PPV-infected <it>Arabidopsis </it>are the molecular basis of stress and defence-like responses, PPV pathogenesis and symptom development. The differentially regulated genes, particularly the early responsive genes, and a common set of genes regulated by infections of PPV and other positive sense RNA viruses identified in this study are candidates suitable for further functional characterization to shed lights on molecular virus-host interactions.</p
Hot and repulsive traffic flow
We study a message passing model, applicable also to traffic problems. The
model is implemented in a discrete lattice, where particles move towards their
destination, with fluctuations around the minimal distance path. A repulsive
interaction between particles is introduced in order to avoid the appearance of
traffic jam. We have studied the parameter space finding regions of fluid
traffic, and saturated ones, being separated by abrupt changes. The improvement
of the system performance is also explored, by the introduction of a
non-constant potential acting on the particles. Finally, we deal with the
behavior of the system when temporary failures in the transmission occurs.Comment: 22 pages, uuencoded gzipped postscript file. 11 figures include
Overlapping-gate architecture for silicon Hall bar MOSFET devices in the low electron density and high magnetic field regime
A common issue in low temperature measurements of enhancement-mode
metal-oxide-semiconductor (MOS) field-effect transistors (FETs) in the low
electron density regime is the high contact resistance dominating the device
impedance. In that case a voltage bias applied across the source and drain
contact of a Hall bar MOSFET will mostly fall across the contacts (and not
across the channel) and therefore magneto-transport measurements become
challenging. However, from a physical point of view, the study of MOSFET
nanostructures in the low electron density regime is very interesting (impurity
limited mobility [1], carrier interactions [2,3] and spin-dependent transport
[4]) and it is therefore important to come up with solutions [5,6] that work
around the problem of a high contact resistance in such devices (c.f. Fig. 1
(a)).Comment: 3 page
A Phase I/IIA Clinical Study With A Chimeric Mouse-Human Monoclonal Antibody To The V3 Loop Of Human Immunodeficiency Virus Type 1 Gp120
A phase I/IIA clinical trial with the chimeric mouse-human monoclonal antibody CGP 47 439 to the principal neutralization determinant in the V3 region of human immunodeficiency virus type 1 (HIV-1) strain IIIB envelope protein gp 120 is reported. The trial was an uncontrolled single-center, open-label, multidose tolerability, immunogenicity, and pharmacokinetic study in homosexual men with advanced HIV disease. Patient groups were formed on the basis of the reactivity of the antibody with the gp 120 of their HIV-1 isolates. Intravenous infusions of 1, 10, and 25 mg of antibody were followed by seven escalated doses of 50, 100, and 200 mg, every 3 weeks. The antibody was well tolerated; no toxicity was observed. Some patients showed a transient but insignificant antibody response to the antibody with no apparent adverse reactions or accelerated elimination of it. Substantial serum levels of the antibody were maintained with a mean t1/2β of 8-16 days. A virus burden reduction was observed in some patient
Ternary complex structures of human farnesyl pyrophosphate synthase bound with a novel inhibitor and secondary ligands provide insights into the molecular details of the enzyme’s active site closure
On a Convex Set with Nondifferentiable Metric Projection
A remarkable example of a nonempty closed convex set in the Euclidean plane
for which the directional derivative of the metric projection mapping fails to
exist was constructed by A. Shapiro. In this paper, we revisit and modify that
construction to obtain a convex set with smooth boundary which possesses the
same property
- …