138 research outputs found
Polyoxometalates for Nonvolatile Memory Applications
[Not available
Dependence of the 0.5(2e2/h) conductance plateau on the aspect ratio of InAs quantum point contacts with in-plane side gates
The observation of a 0.5 conductance plateau in asymmetrically biased quantum
point contacts with in-plane side gates has been attributed to the onset of
spin-polarized current through these structures. For InAs quantum point
contacts with the same width but longer channel length, there is roughly a
fourfold increase in the range of common sweep voltage applied to the side
gates over which the 0.5 conductance plateau is observed when the QPC aspect
ratio (ratio of length over width of the narrow portion of the structure) is
increased by a factor 3. Non-equilibrium Green s function simulations indicate
that the increase in the size of the 0.5 conductance plateau is due to an
increased importance, over a larger range of common sweep voltage, of the
effects of electron-electron interactions in QPC devices with larger aspect
ratio. The use of asymmetrically biased QPCs with in-plane side gates and large
aspect ratio could therefore pave the way to build robust spin injectors and
detectors for the successful implementation of spin field effect transistorsComment: 30 pages, 9 figure
Phosphoinositide hydrolysis mediated by H1 receptors in autoimmune myocarditis mice
Stimulation of phosphoinositide hydrolysis in myocardium from autoimmune myocarditis mice by ThEA and histamine was assayed. Myocardium from autoimmune heart, but not the normal forms, specifically increased phosphoinositide turnover in the presence of histaminergic agonists. This increment was blocked by a specific H1 antagonist mepyramine and to the same extent by the phospholipase C inhibitor NCDC. By using a binding assay H1 histaminergic receptors were detected in autoimmune heart membrane preparations, but this was not observed in normal heart. These data suggest that autoimmune myocardium expressed a functional H1 receptor that could involve a distinctive mechanism operating in the disease
Cholinoceptor Activation Subserving the Effects of Interferon Gamma on the Contractility of Rat Ileum
Recombinant rat interferon γ stimulated the contractility of
isolated rat ileum at doses of 4–12 units/ml. Muscarinic
cholinoceptors were involved, as treatment of the tissue with
atropine prevented the contractile response of the ileum.
Furthermore, interferon γ increased the affinity of carbachol for
the cholinoceptors and did not change its maximum effect. Neurogenic
pathways were also involved since pretreatment of ileum with
hexamethonium, hemicholinium or tetrodotoxin impaired the
contractile effect of interferon γ. In contrast to the action of
exogenous carbachol, the effects of interferon γ are indirect. They
appear to involve a G protein regulating phosphoinositide turnover
and cytoskeletal structures since they could not be induced in ileum
strips that were pretreated with pertussis toxin, phospholipase C
inhibitors (2-nitro-carboxyphenyl, NN-diphenyl carbamate and
neomycin), cytochalasine B or colchicine
Synthesis And Characterization Of Graphene Oxide –Polyoxometalate Composite Material For Device Applications
Polyoxometalates (POMs) consisting of clusters of d-block transition metals and oxygen
atoms represent an important class of water soluble polynuclear nanomaterial. The tuneable
size, structure and elemental composition of POM draws considerable attention for the
development of functional composite materials of desired chemical and electronic
properties.[1] Graphene can be the promising support for POMs due to its low band gap
energy and fast electron transport properties. These properties of grapheme facilitates
transport of electrons of POMs rapidly and effectively.[2] In the present investigation,
graphene oxide (GO) and reduced graphene oxide (rGO) have been used as a support for
POM-graphene composites for semiconductor, hydrogen production applications.[2] The
deposition of POM on graphene oxide sheets were carried out through electron transfer
interaction and electrostatic interaction between POM and GO sheets. ...
Description of the ERA-CLIM historical upper-air data
Historical, i.e. pre-1957, upper-air data are a valuable source of
information on the state of the atmosphere, in some parts of the world dating back
to the early 20th century. However, to date, reanalyses have only
partially made use of these data, and only of observations made after 1948.
Even for the period between 1948 (the starting year of the NCEP/NCAR (National Centers for Environmental
Prediction/National Center for Atmospheric Research) reanalysis) and the International Geophysical Year in 1957 (the starting
year of the ERA-40 reanalysis), when the global upper-air coverage reached
more or less its current status, many observations have not yet been digitised. The Comprehensive Historical Upper-Air Network (CHUAN) already
compiled a large collection of pre-1957 upper-air data. In the framework of
the European project ERA-CLIM (European Reanalysis of Global Climate Observations), significant amounts of additional upper-air
data have been catalogued (> 1.3 million station days), imaged
(> 200 000 images) and digitised (> 700 000 station
days) in order to prepare a new input data set for upcoming reanalyses. The
records cover large parts of the globe, focussing on, so far, less well
covered regions such as the tropics, the polar regions and the oceans, and
on very early upper-air data from Europe and the US. The total number of
digitised/inventoried records is 61/101 for moving upper-air data, i.e. data
from ships, etc., and 735/1783 for fixed upper-air stations. Here, we give a
detailed description of the resulting data set including the metadata and the
quality checking procedures applied. The data will be included in the next
version of CHUAN. The data are available at <a href="http://dx.doi.org/10.1594/PANGAEA.821222"target="_blank">doi:10.1594/PANGAEA.821222</a>
Uncertainty in Signals of Large-Scale Climate Variations in Radiosonde and Satellite Upper-Air Temperature Datasets
There is no single reference dataset of long-term global upper-air temperature observations, although several
groups have developed datasets from radiosonde and satellite observations for climate-monitoring purposes. The
existence of multiple data products allows for exploration of the uncertainty in signals of climate variations and
change. This paper examines eight upper-air temperature datasets and quantifies the magnitude and uncertainty
of various climate signals, including stratospheric quasi-biennial oscillation (QBO) and tropospheric ENSO
signals, stratospheric warming following three major volcanic eruptions, the abrupt tropospheric warming of
1976–77, and multidecadal temperature trends. Uncertainty estimates are based both on the spread of signal
estimates from the different observational datasets and on the inherent statistical uncertainties of the signal in
any individual dataset.
The large spread among trend estimates suggests that using multiple datasets to characterize large-scale upperair
temperature trends gives a more complete characterization of their uncertainty than reliance on a single
dataset. For other climate signals, there is value in using more than one dataset, because signal strengths vary.
However, the purely statistical uncertainty of the signal in individual datasets is large enough to effectively
encompass the spread among datasets. This result supports the notion of an 11th climate-monitoring principle,
augmenting the 10 principles that have now been generally accepted (although not generally implemented) by
the climate community. This 11th principle calls for monitoring key climate variables with multiple, independent
observing systems for measuring the variable, and multiple, independent groups analyzing the data
Maintaining friendships in early stage dementia: Factors to consider
Friendships and the importance of social connectiveness play a critical role in aging well, regardless of gender, race, social class, or impairment. Yet, dementia takes its toll on social relationships, and many friends withdraw and ‘disappear’, because they can no longer bear to see the changes that are taking place in their diagnosed friend. The dementia care literature documents this abandonment; however, this study examines the opposite occurrence. In order to understand more clearly the role of long-term friendships and how such friendships remain and continue, despite the diagnosis of dementia, this qualitative study examines in depth eight people in the early stages of dementia who have been able to maintain strong friendships despite the diagnosis. Factors that seem to play important roles are: (1) the importance of the friendships, (2) factors affecting the quality of the relationships, (3) mutually beneficial relationships, (4) core values, (5) acceptance and disclosure, and (6) recognition of strengths and understanding of limitations
Perspectives on the Trypanosoma cruzi-host cell receptor interaction
Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets
Dynamical Study of the Delta Excitation in N(e,e' pi) Reactions
The dynamical model developed in [Phys. Rev. C 54, 2660 (1996)] has been
applied to investigate the pion electroproduction reactions on the nucleon. It
is found that the model can describe to a very large extent the recent data of
p(e,e' pi^0) reaction from Jefferson Laboratory and MIT-Bates. The extracted
magnetic dipole(M1), electric dipole(E2), and Coulomb(C2) strengths of the
gamma N -> Delta transition are presented. It is found that the C2/M1 ratio
drops significantly with Q^2 and reaches about -13% at Q^2=4 (GeV/c)^2, while
the E2/M1 ratio remains close to the value \sim -3 % at the Q^2=0 photon point.
The determined M1 transition form factor drops faster than the usual dipole
form factor of the proton. We also find that the non-resonant interactions can
dress the gamma N -> Delta vertex to enhance strongly its strength at low Q^2,
but much less at high Q^2. Predictions are presented for future experimental
tests. Possible developments of the model are discussed.Comment: 39 pages,17 figures, with RevTeX, to be submitted Phys. Rev.
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