2,506 research outputs found
Degrees of controllability for quantum systems and applications to atomic systems
Precise definitions for different degrees of controllability for quantum
systems are given, and necessary and sufficient conditions are discussed. The
results are applied to determine the degree of controllability for various
atomic systems with degenerate energy levels and transition frequencies.Comment: 20 pages, IoP LaTeX, revised and expanded versio
Monte Carlo simulations of spin transport in nanoscale In0.7Ga0.3As transistors: temperature and size effects
Spin-based metal-oxide-semiconductor field-effect transistors (MOSFET) with a
high-mobility III-V channel are studied using self-consistent quantum corrected
ensemble Monte Carlo device simulations of charge and spin transport. The
simulations including spin-orbit coupling mechanisms (Dresselhaus and Rashba
coupling) examine the electron spin transport in the 25 nm gate length
InGaAs MOSFET. The transistor lateral dimensions (the gate
length, the source-to-gate, and the gate-to-drain spacers) are increased to
investigate the spin-dependent drain current modulation induced by the gate
from room temperature of 300 K down to 77 K. This modulation increases with
increasing temperature due to increased Rashba coupling. Finally, an increase
of up to 20 nm in the gate length, source-to-gate, or the gate-to-drain spacers
increases the spin polarization and enhances the spin-dependent drain current
modulation at the drain due to polarization-refocusing effects
Clinical and functional characterisation of a novel TNFRSF1A c.605T > A/V173D cleavage site mutation associated with tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS), cardiovascular complications and excellent response to etanercept treatment.
Objectives: To study the clinical outcome, treatment
response, T-cell subsets and functional consequences of a
novel tumour necrosis factor (TNF) receptor type 1
(TNFRSF1A) mutation affecting the receptor
cleavage site.
Methods: Patients with symptoms suggestive of tumour
necrosis factor receptor-associated periodic syndrome
(TRAPS) and 22 healthy controls (HC) were screened for
mutations in the TNFRSF1A gene. Soluble TNFRSF1A and
inflammatory cytokines were measured by ELISAs.
TNFRSF1A shedding was examined by stimulation of
peripheral blood mononuclear cells (PBMCs) with phorbol
12-myristate 13-acetate followed by flow cytometric
analysis (FACS). Apoptosis of PBMCs was studied by
stimulation with TNFa in the presence of cycloheximide
and annexin V staining. T cell phenotypes were monitored
by FACS.
Results: TNFRSF1A sequencing disclosed a novel V173D/
p.Val202Asp substitution encoded by exon 6 in one
family, the c.194–14G.A splice variant in another and
the R92Q/p.Arg121Gln substitution in two families.
Cardiovascular complications (lethal heart attack and
peripheral arterial thrombosis) developed in two V173D
patients. Subsequent etanercept treatment of the V173D
carriers was highly effective over an 18-month follow-up
period. Serum TNFRSF1A levels did not differ between
TRAPS patients and HC, while TNFRSF1A cleavage from
monocytes was significantly reduced in V173D and R92Q
patients. TNFa-induced apoptosis of PBMCs and T-cell
senescence were comparable between V173D patients
and HC.
Conclusions: The TNFRSF1A V173D cleavage site
mutation may be associated with an increased risk for
cardiovascular complications and shows a strong
response to etanercept. T-cell senescence does not seem
to have a pathogenetic role in affected patients
The effect of spatial resolution on optical and near-IR studies of stellar clusters: Implications for the origin of the red excess
Recent ground based near-IR studies of stellar clusters in nearby galaxies
have suggested that young clusters remain embedded for 7-10Myr in their
progenitor molecular cloud, in conflict with optical based studies which find
that clusters are exposed after 1-3Myr. Here, we investigate the role that
spatial resolution plays in this apparent conflict. We use a recent catalogue
of young (~\msun) clusters in the nearby spiral
galaxy, M83, along with Hubble Space Telescope (HST) imaging in the optical and
near-IR, and ground based near-IR imaging, to see how the colours (and hence
estimated properties such as age and extinction) are affected by the aperture
size employed, in order to simulate studies of differing resolution. We find
that the near-IR is heavily affected by the resolution, and when aperture sizes
~pc are used, all young/blue clusters move red-ward in colour space, which
results in their appearance as heavily extincted clusters. However, this is due
to contamination from nearby sources and nebular emission, and is not an
extinction effect. Optical colours are much less affected by resolution. Due to
the larger affect of contamination in the near-IR, we find that, in some cases,
clusters will appear to show near-IR excess when large (~pc) apertures are
used. Our results explain why few young (~Myr), low extinction (\av <
1~mag) clusters have been found in recent ground based near-IR studies of
cluster populations, while many such clusters have been found in higher
resolution HST based studies. Additionally, resolution effects appear to (at
least partially) explain the origin of the near-IR excess that has been found
in a number of extragalactic YMCs.Comment: 8 pages, 5 figures, accepted for publication in MNRA
Emotion Effects on Timing: Attention versus Pacemaker Accounts
Emotions change our perception of time. In the past, this has been attributed primarily to emotions speeding up an “internal clock” thereby increasing subjective time estimates. Here we probed this account using an S1/S2 temporal discrimination paradigm. Participants were presented with a stimulus (S1) followed by a brief delay and then a second stimulus (S2) and indicated whether S2 was shorter or longer in duration than S1. We manipulated participants' emotions by presenting a task-irrelevant picture following S1 and preceding S2. Participants were more likely to judge S2 as shorter than S1 when the intervening picture was emotional as compared to neutral. This effect held independent of S1 and S2 modality (Visual: Exps. 1, 2, & 3; Auditory: Exp. 4) and intervening picture valence (Negative: Exps. 1, 2 & 4; Positive: Exp. 3). Moreover, it was replicated in a temporal reproduction paradigm (Exp. 5) where a timing stimulus was preceded by an emotional or neutral picture and participants were asked to reproduce the duration of the timing stimulus. Taken together, these findings indicate that emotional experiences may decrease temporal estimates and thus raise questions about the suitability of internal clock speed explanations of emotion effects on timing. Moreover, they highlight attentional mechanisms as a viable alternative
Spin recovery in the 25nm gate length InGaAs field effect transistore
We augmented an ensemble Monte-Carlo semiconductor device simulator [3] to incorporate electron spin degrees of freedom using a Bloch equation model to investigate the feasibility of spintronic devices. Results are presented for the steady state polarization and polarization decay due to scattering and spin orbit coupling for a III-V MOSFET device as a function of gate voltages, injection polarization and strain
Transcriptomics in ecotoxicology
The emergence of analytical tools for high-throughput screening of biomolecules has revolutionized the way in which toxicologists explore the impact of chemicals or other stressors on organisms. One of the most developed and routinely applied high-throughput analysis approaches is transcriptomics, also often referred to as gene expression profiling. The transcriptome represents all RNA molecules, including the messenger RNA (mRNA), which constitutes the building blocks for translating DNA into amino acids to form proteins. The entirety of mRNA is a mirror of the genes that are actively expressed in a cell or an organism at a given time. This in turn allows one to deduce how organisms respond to changes in the external environment. In this article we explore how transcriptomics is currently applied in ecotoxicology and highlight challenges and trends
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