2,327 research outputs found
Tapered-amplified AR-coated laser diodes for Potassium and Rubidium atomic-physics experiments
We present a system of room-temperature extended-cavity grating-diode lasers
(ECDL) for production of light in the range 760-790nm. The extension of the
tuning range towards the blue is permitted by the weak feedback in the cavity:
the diodes are anti-reflection coated, and the grating has just 10%
reflectance. The light is then amplified using semiconductor tapered amplifiers
to give more than 400mW of power. The outputs are shown to be suitable for
atomic physics experiments with potassium (767nm), rubidium (780nm) or both, of
particular relevance to doubly-degenerate boson-fermion mixtures
Crude glycerol in the diets of the juveniles ofAmazon catfish(female Pseudoplatystoma punctifer x male Leiarius marmoratus)
This research aimed to determine the best inclusion level of crude glycerol in the diet of the Amazon catfish (Pintado), through zootechnical performance, body composition, metabolic profile and histopathology. The experiment was conducted at the Laboratory of Morphophysiology and Biochemistry of Neotropical Fishes of the Federal University of Tocantins. There was used 150 juvenilles of pintado, these with initial weight of 6,83 ± 1,11 (g) and 10,06 ± 0,57 (cm) lenght in a completely randomised design, with 3 replications (10 animals in each one). They were fed with five diets containing increasing levels of glycerol (0 g kg-1, 50 g kg-1, 75 g kg-1, 100 g kg-1, and 125 g kg-1) during 90 days (30 days of adaption and 60 experimental days). The indexes were evaluated and they did not present statistical difference between each other, except for the specific growth rate, which showed a moderate linear behavior and muscular glycogen that at the level of 125 g kg-1 presented a lower concentration compared with the control diet (0 g kg-1). Regarding histology, the crude glycerin did not cause significant hepatic and renal changes in the referred specie, since the alterations found in the two tissues were considered lesions that did not compromise the functioning of the organ or that are reversible. Finally, it was indicated that the juveniles of Amazon Pintado are able to metabolize the crude glycerin up to 100 g kg-1level
MAD@VLT: Deep into the Madding Crowd of Omega Centauri
We present deep and accurate Near-Infrared (NIR) photometry of the Galactic
Globular Cluster (GC) Omega Cen. Data were collected using the Multi-Conjugate
Adaptive Optics Demonstrator (MAD) on VLT (ESO). The unprecedented quality of
the images provided the opportunity to perform accurate photometry in the
central crowded regions. Preliminary results indicate that the spread in age
among the different stellar populations in Omega Cen is limited.Comment: 6 pages, 3 figures, to appear in the Springer Astrophysics and Space
Science Proceedings, "Science with the VLT in the ELT era", ed. A. Moorwoo
Measurement of shower development and its Moli\`ere radius with a four-plane LumiCal test set-up
A prototype of a luminometer, designed for a future e+e- collider detector,
and consisting at present of a four-plane module, was tested in the CERN PS
accelerator T9 beam. The objective of this beam test was to demonstrate a
multi-plane tungsten/silicon operation, to study the development of the
electromagnetic shower and to compare it with MC simulations. The Moli\`ere
radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using
a parametrization of the shower shape. Very good agreement was found between
data and a detailed Geant4 simulation.Comment: Paper published in Eur. Phys. J., includes 25 figures and 3 Table
Performance of fully instrumented detector planes of the forward calorimeter of a Linear Collider detector
Detector-plane prototypes of the very forward calorimetry of a future
detector at an e+e- collider have been built and their performance was measured
in an electron beam. The detector plane comprises silicon or GaAs pad sensors,
dedicated front-end and ADC ASICs, and an FPGA for data concentration.
Measurements of the signal-to-noise ratio and the response as a function of the
position of the sensor are presented. A deconvolution method is successfully
applied, and a comparison of the measured shower shape as a function of the
absorber depth with a Monte-Carlo simulation is given.Comment: 25 pages, 32 figures, revised version following comments from
referee
Climate dynamics and fluid mechanics: Natural variability and related uncertainties
The purpose of this review-and-research paper is twofold: (i) to review the
role played in climate dynamics by fluid-dynamical models; and (ii) to
contribute to the understanding and reduction of the uncertainties in future
climate-change projections. To illustrate the first point, we focus on the
large-scale, wind-driven flow of the mid-latitude oceans which contribute in a
crucial way to Earth's climate, and to changes therein. We study the
low-frequency variability (LFV) of the wind-driven, double-gyre circulation in
mid-latitude ocean basins, via the bifurcation sequence that leads from steady
states through periodic solutions and on to the chaotic, irregular flows
documented in the observations. This sequence involves local, pitchfork and
Hopf bifurcations, as well as global, homoclinic ones. The natural climate
variability induced by the LFV of the ocean circulation is but one of the
causes of uncertainties in climate projections. Another major cause of such
uncertainties could reside in the structural instability in the topological
sense, of the equations governing climate dynamics, including but not
restricted to those of atmospheric and ocean dynamics. We propose a novel
approach to understand, and possibly reduce, these uncertainties, based on the
concepts and methods of random dynamical systems theory. As a very first step,
we study the effect of noise on the topological classes of the Arnol'd family
of circle maps, a paradigmatic model of frequency locking as occurring in the
nonlinear interactions between the El Nino-Southern Oscillations (ENSO) and the
seasonal cycle. It is shown that the maps' fine-grained resonant landscape is
smoothed by the noise, thus permitting their coarse-grained classification.
This result is consistent with stabilizing effects of stochastic
parametrization obtained in modeling of ENSO phenomenon via some general
circulation models.Comment: Invited survey paper for Special Issue on The Euler Equations: 250
Years On, in Physica D: Nonlinear phenomen
ECFA Detector R&D Panel, Review Report
Two special calorimeters are foreseen for the instrumentation of the very
forward region of an ILC or CLIC detector; a luminometer (LumiCal) designed to
measure the rate of low angle Bhabha scattering events with a precision better
than 10 at the ILC and 10 at CLIC, and a low polar-angle
calorimeter (BeamCal). The latter will be hit by a large amount of
beamstrahlung remnants. The intensity and the spatial shape of these
depositions will provide a fast luminosity estimate, as well as determination
of beam parameters. The sensors of this calorimeter must be radiation-hard.
Both devices will improve the e.m. hermeticity of the detector in the search
for new particles. Finely segmented and very compact electromagnetic
calorimeters will match these requirements. Due to the high occupancy, fast
front-end electronics will be needed. Monte Carlo studies were performed to
investigate the impact of beam-beam interactions and physics background
processes on the luminosity measurement, and of beamstrahlung on the
performance of BeamCal, as well as to optimise the design of both calorimeters.
Dedicated sensors, front-end and ADC ASICs have been designed for the ILC and
prototypes are available. Prototypes of sensor planes fully assembled with
readout electronics have been studied in electron beams.Comment: 61 pages, 51 figure
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