1,528 research outputs found
Resolution studies of cosmic-ray tracks in a TPC with GEM readout
A large volume TPC is a leading candidate for the central tracking detector
at a future high energy linear collider. To improve the resolution a new
readout based on micro-pattern gas detectors is being developed. Measurements
of the spatial resolution of cosmic-ray tracks in a GEM TPC are presented. We
find that the resolution suffers if the readout pads are too wide with respect
to the charge distribution at the readout plane due to insufficient charge
sharing. For narrow pads of 2 x 6 mm**2 we measure a resolution of 100
micometer at short drift distances in the absence of an axial magnetic field.
The dependence of the spatial resolution as a function of drift distance allows
the determination of the underlying electron statistics. Our results show that
the present technique uses about half the statistical power available from the
number of primary electrons. The track angle effect is observed as expected.Comment: 18 pages, 8 figures, version as published in Nucl. Inst. Met
Measurement of electron screening in muonic lead
Energies of the transitions between high-lying (n≥6) states of muonic lead were accurately determined. The results are interpreted as a ∼2% test of the electron screening. The agreement between experiment and theory is good if it is assumed that the refilling of the electron K shell is fast. The present results furthermore severely restrict possible ionization of the electron L shell
Swimming exercise enhances brain plasticity in fish
It is well-established that sustained exercise training can enhance brain plasticity and boost cognitive performance in mammals, but this phenomenon has not received much attention in fish. The aim of this study was to determine whether sustained swimming exercise can enhance brain plasticity in juvenile Atlantic salmon. Brain plasticity was assessed by both mapping the whole telencephalon transcriptome and conducting telencephalic region-specific microdissections on target genes. We found that 1772 transcripts were differentially expressed between the exercise and control groups. Gene ontology (GO) analysis identified 195 and 272 GO categories with a significant overrepresentation of up- or downregulated transcripts, respectively. A multitude of these GO categories was associated with neuronal excitability, neuronal signalling, cell proliferation and neurite outgrowth (i.e. cognition-related neuronal markers). Additionally, we found an increase in proliferating cell nuclear antigen (pcna) after both three and eight weeks of exercise in the equivalent to the hippocampus in fish. Furthermore, the expression of the neural plasticity markers synaptotagmin (syt) and brain-derived neurotrophic factor (bdnf) were also increased due to exercise in the equivalent to the lateral septum in fish. In conclusion, this is the first time that swimming exercise has been directly linked to increased telencephalic neurogenesis and neural plasticity in a teleost, and our results pave the way for future studies on exercise-induced neuroplasticity in fish.</p
Reduced breeding success of cormorants (Phalacrocorax carbo sinensis) in relation to persistent organochlorine pollution of aquatic habitats in the netherlands.
Parallel Gaussian Process Optimization with Upper Confidence Bound and Pure Exploration
In this paper, we consider the challenge of maximizing an unknown function f
for which evaluations are noisy and are acquired with high cost. An iterative
procedure uses the previous measures to actively select the next estimation of
f which is predicted to be the most useful. We focus on the case where the
function can be evaluated in parallel with batches of fixed size and analyze
the benefit compared to the purely sequential procedure in terms of cumulative
regret. We introduce the Gaussian Process Upper Confidence Bound and Pure
Exploration algorithm (GP-UCB-PE) which combines the UCB strategy and Pure
Exploration in the same batch of evaluations along the parallel iterations. We
prove theoretical upper bounds on the regret with batches of size K for this
procedure which show the improvement of the order of sqrt{K} for fixed
iteration cost over purely sequential versions. Moreover, the multiplicative
constants involved have the property of being dimension-free. We also confirm
empirically the efficiency of GP-UCB-PE on real and synthetic problems compared
to state-of-the-art competitors
Combined dietary supplementation of long chain inulin and Lactobacillus acidophilus W37 supports oral vaccination efficacy against Salmonella Typhimurium in piglets
Routine use of antibiotics in livestock animals strongly contributed to the creation of multidrug-resistant Salmonella Typhimurium strains (STM). Vaccination is an alternative to the use of antibiotics but often suffers from low efficacy. The present study investigated whether long-chain inulin (lcITF) and Lactobacillus acidophilus W37 (LaW37) can support vaccination efficacy against STM and if the interventions influence possible gut microbiota changes. Piglets received daily supplementation until sacrifice. Animals were vaccinated on day 25 after birth, one day after weaning, and were challenged with STM on days 52-54. Dietary intervention with lcITF/LaW37 enhanced vaccination efficacy by 2-fold during challenge and resulted in higher relative abundance of Prevotellaceae and lower relative abundance of Lactobacillaceae in faeces. Although strongest microbial effects were observed post STM challenge on day 55, transient effects of the lcITF/LaW37 intervention were also detected on day 10 after birth, and post-weaning on day 30 where increased relative abundance of faecal lactobacilli was correlated with higher faecal consistency. LcITF treatment increased post-weaning feed efficiency and faecal consistency but did not support vaccination efficacy. Vaccination in immune-immature young animals can be enhanced with functional additives which can simultaneously promote health in an ingredient-dependent fashion
Determination of alpha_s using Jet Rates at LEP with the OPAL detector
Hadronic events produced in e+e- collisions by the LEP collider and recorded
by the OPAL detector were used to form distributions based on the number of
reconstructed jets. The data were collected between 1995 and 2000 and
correspond to energies of 91 GeV, 130-136 GeV and 161-209 GeV. The jet rates
were determined using four different jet-finding algorithms (Cone, JADE, Durham
and Cambridge). The differential two-jet rate and the average jet rate with the
Durham and Cambridge algorithms were used to measure alpha(s) in the LEP energy
range by fitting an expression in which order alpah_2s calculations were
matched to a NLLA prediction and fitted to the data. Combining the measurements
at different centre-of-mass energies, the value of alpha_s (Mz) was determined
to be
alpha(s)(Mz)=0.1177+-0.0006(stat.)+-0.0012$(expt.)+-0.0010(had.)+-0.0032(theo.)
\.Comment: 40 pages, 17 figures, Submitted to Euro. Phys. J.
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