8,724 research outputs found
Human resourcing in academic libraries : the 'lady librarian', the call for flexible staff and the need to be counted
This paper reports on a recent set of research findings into human resource (HR) deployment in academic, college and national libraries in the UK and Ireland by selectively summarising these findings. The recommendations are that libraries should make available for comparison by others not only their library service provision, i.e. opening hours, but also staff provision, i.e. staffing numbers and demographics and staff deployment, with a view to benchmarking levels of flexibility. This work highlights the lack of existing benchmarking facilities in UK universities and colleges of higher education, relating to HR deployment in libraries, and recommends that Sconul extends the existing data collection in its Annual Statistical return to include this HR area
Gene expression analysis of bovine embryonic disc, trophoblast and parietal hypoblast at the start of gastrulation
In cattle early gastrulation-stage embryos (Stage 5), four tissues can be discerned: (i) the top layer of the embryonic disc consisting of embryonic ectoderm (EmE); (ii) the bottom layer of the disc consisting of mesoderm, endoderm and visceral hypoblast (MEH); (iii) the trophoblast (TB); and (iv) the parietal hypoblast. We performed microsurgery followed by RNA-seq to analyse the transcriptome of these four tissues as well as a developmentally earlier pre-gastrulation embryonic disc. The cattle EmE transcriptome was similar at Stages 4 and 5, characterised by the OCT4/SOX2/NANOG pluripotency network. Expression of genes associated with primordial germ cells suggest their presence in the EmE tissue at these stages. Anterior visceral hypoblast genes were transcribed in the Stage 4 disc, but no longer by Stage 5. The Stage 5 MEH layer was equally similar to mouse embryonic and extraembryonic visceral endoderm. Our data suggest that the first mesoderm to invaginate in cattle embryos is fated to become extraembryonic. TGFβ, FGF, VEGF, PDGFA, IGF2, IHH and WNT signals and receptors were expressed, however the representative members of the FGF families differed from that seen in equivalent tissues of mouse embryos. The TB transcriptome was unique and differed significantly from that of mice. FGF signalling in the TB may be autocrine with both FGFR2 and FGF2 expressed. Our data revealed a range of potential inter-tissue interactions, highlighted significant differences in early development between mice and cattle and yielded insight into the developmental events occurring at the start of gastrulation
Spin-Dependent Tunneling of Single Electrons into an Empty Quantum Dot
Using real-time charge sensing and gate pulsing techniques we measure the
ratio of the rates for tunneling into the excited and ground spin states of a
single-electron AlGaAs/GaAs quantum dot in a parallel magnetic field. We find
that the ratio decreases with increasing magnetic field until tunneling into
the excited spin state is completely suppressed. However, we find that by
adjusting the voltages on the surface gates to change the orbital configuration
of the dot we can restore tunneling into the excited spin state and that the
ratio reaches a maximum when the dot is symmetric.Comment: 4 pages, 3 figure
Serotonin signaling through the 5-HT1B receptor and NADPH oxidase 1 in pulmonary arterial hypertension
Objective: Serotonin can induce human pulmonary artery smooth muscle cell (hPASMC) proliferation through reactive oxygen species (ROS), influencing the development of pulmonary arterial hypertension (PAH). We hypothesise that in PASMCs, serotonin induces oxidative stress through NADPH-oxidase-derived ROS generation and reduced Nrf-2 anti-oxidant systems, promoting vascular injury.
Approach and Results: HPASMCs from controls and PAH patients, and PASMCs from Nox1-/- mice, were stimulated with serotonin in the absence/presence of inhibitors of Src kinase, the 5-HT1B receptor and NADPH oxidase 1 (Nox1). Markers of fibrosis were also determined. The pathophysiological significance of our findings was examined in vivo in serotonin transporter overexpressing (SERT+) female mice, a model of pulmonary hypertension (PH).
We confirmed serotonin increased superoxide and H2O2 production in these cells. For the first time, we show that serotonin increased oxidized protein tyrosine phosphatases and peroxiredoxin-SO3H and decreased Nrf-2 and catalase activity in hPASMCs. ROS generation was exaggerated, and dependent on c-Src, 5-HT1B receptor and the serotonin transporter in PAH-hPASMCs. Proliferation and extracellular matrix remodeling were exaggerated in PAH-hPASMCs and dependent on 5-HT1B receptor signaling and Nox1, confirmed in PASMCs from Nox1-/- mice. In SERT+ mice, SB216641, a 5-HT1B receptor antagonist, prevented development of PH in a ROS-dependent manner.
Conclusions: Serotonin can induce c-Src-regulated Nox1-induced ROS and Nrf-2 dysregulation, contributing to increased post-translational oxidative modification of proteins, activation of redox-sensitive signaling pathways in hPASMCs; associated with mitogenic responses. 5-HT1B receptors contribute to experimental PH by inducing lung ROS production. Our results suggest 5-HT1B receptor-dependent c-Src-Nox1-pathways contribute to vascular remodeling in PAH
Electrical control of spin relaxation in a quantum dot
We demonstrate electrical control of the spin relaxation time T_1 between
Zeeman split spin states of a single electron in a lateral quantum dot. We find
that relaxation is mediated by the spin-orbit interaction, and by manipulating
the orbital states of the dot using gate voltages we vary the relaxation rate
W= (T_1)^-1 by over an order of magnitude. The dependence of W on orbital
confinement agrees with theoretical predictions and from these data we extract
the spin-orbit length. We also measure the dependence of W on magnetic field
and demonstrate that spin-orbit mediated coupling to phonons is the dominant
relaxation mechanism down to 1T, where T_1 exceeds 1s.Comment: 4 pages, 3 figure
Detection of solvents using a distributed fibre optic sensor
A fibre optic sensor that is capable of distributed detection of liquid solvents is presented. Sensor interrogation using optical time domain reflectometry (OTDR) provides the capability of locating solvent spills to a precision of ±2 m over a total sensor length that may extend to 20 km
The effect of iron-oxidising bacteria on the stability of gold (I) thiosulphate complex
An acidophilic, iron-oxidising bacterial consortium was collected from Rio Tinto near Berrocal, Spain. This primary enriched culture was used to examine the effect of acidophilic iron-oxidising bacteria on the stability of soluble gold (I) thiosulphate. Stationary phase cultures and separate components of the cultures (i.e., aqueous ferric iron, iron oxyhydroxide precipitates and non-mineralised bacterial cells) were exposed to gold (I) thiosulphate solutions forming different experimental-gold systems. These experimental systems rapidly removed gold from solutions containing 0.002 mM–20 mM gold thiosulphate. Scanning and transmission electron microscopy demonstrated that the different culture fractions immobilised gold differently: the entire bacterial culture-gold systems precipitated 100 nm-size gold colloids; aqueous ferric iron–gold systems precipitated colloidal gold sulphide that ranged in diameter from 200 nm to 2 μm; iron oxyhydroxide-gold systems precipitated 5 nm-size gold sulphide colloids; and the bacteria-gold systems precipitated gold colloids ~ 2 nm in size along the bacterial cell envelope. Aqueous and solid ferric iron was critical in the destabilisation of the gold (I) thiosulphate complex. Analysis of the entire bacterial culture-, aqueous ferric iron- and iron oxyhydroxide-gold systems exposed to 2 mM gold using X-ray absorption near edge spectroscopy demonstrated that Au+ was immobilised from solution as gold sulphide (Au2S). The reaction between iron-oxidising bacteria and their ferric iron by-products with gold (I) thiosulphate demonstrated that thiosulphate ions would be an unstable gold complexing ligand in nature. Gold (I) thiosulphate is intuitively transformed into nanometer-scale gold sulphide or elemental gold within natural, acidic weathering environments with the potential to precipitate gold in jarosite that can subsequently be preserved in gossans over geological time
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