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

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

Non-equilibrium spin noise spectroscopy of a single quantum dot operating at fiber telecommunication wavelengths

We report on the spin and occupation noise of a single, positively charged (InGa)As quantum dot emitting photons in the telecommunication C-band. The spin noise spectroscopy measurements are carried out at a temperature of 4.2 K in dependence on intensity and detuning in the regime beyond thermal equilibrium. The spin noise spectra yield in combination with an elaborate theoretical model the hole-spin relaxation time of the positively charged quantum dot and the Auger recombination and the electron-spin relaxation time of the trion state. The extracted Auger recombination time of this quantum dot emitting at 1.55 μm is comparable to the typical Auger recombination times on the order of a few μs measured in traditionally grown InAs/GaAs quantum dots emitting at around 900 nm

Symbolic Model Checking of Product-Line Requirements Using SAT-Based Methods

Product line (PL) engineering promotes the de- velopment of families of related products, where individual products are differentiated by which optional features they include. Modelling and analyzing requirements models of PLs allows for early detection and correction of requirements errors – including unintended feature interactions, which are a serious problem in feature-rich systems. A key challenge in analyzing PL requirements is the efficient verification of the product family, given that the number of products is too large to be verified one at a time. Recently, it has been shown how the high-level design of an entire PL, that includes all possible products, can be compactly represented as a single model in the SMV language, and model checked using the NuSMV tool. The implementation in NuSMV uses BDDs, a method that has been outperformed by SAT-based algorithms. In this paper we develop PL model checking using two leading SAT-based symbolic model checking algorithms: IMC and IC3. We describe the algorithms, prove their correctness, and report on our implementation. Evaluating our methods on three PL models from the literature, we demonstrate an improvement of up to 3 orders of magnitude over the existing BDD-based method.NSERC Discovery Grant, 155243-12 || NSERC / Automotive Partnership Canada, APCPJ 386797 - 09 || Ontario Research Fund, RE05-04

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

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

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