85 research outputs found
Violencia de Género: Detección y Pautas de Actuación
En este curso se contempla la violencia de género desde una perspectiva humana, social, asistencial y jurídica.
Se matizarán las principales diferencias y características entre violencia de género y violencia doméstica así como las posibles respuestas a los casos que se nos planteen
Así se destacarán las pautas de actuación ante una víctima de violencia de género y un maltratador
Seminario sobre TFG
El objetivo de esta presentación es ofrecer una información clara y precisa sobre cómo hacer un TFG así como ofrecer herramientas para su elaboració
A GPU-based Correlator X-engine Implemented on the CHIME Pathfinder
We present the design and implementation of a custom GPU-based compute
cluster that provides the correlation X-engine of the CHIME Pathfinder radio
telescope. It is among the largest such systems in operation, correlating
32,896 baselines (256 inputs) over 400MHz of radio bandwidth. Making heavy use
of consumer-grade parts and a custom software stack, the system was developed
at a small fraction of the cost of comparable installations. Unlike existing
GPU backends, this system is built around OpenCL kernels running on
consumer-level AMD GPUs, taking advantage of low-cost hardware and leveraging
packed integer operations to double algorithmic efficiency. The system achieves
the required 105TOPS in a 10kW power envelope, making it among the most
power-efficient X-engines in use today.Comment: 6 pages, 5 figures. Accepted by IEEE ASAP 201
Calibrating CHIME, A New Radio Interferometer to Probe Dark Energy
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit
interferometer currently being built at the Dominion Radio Astrophysical
Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral
hydrogen in the frequency range 400 -- 800\,MHz over half of the sky, producing
a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 --
2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that
will yield constraints on the BAO power spectrum and provide a test-bed for our
calibration scheme. I will discuss the CHIME calibration requirements and
describe instrumentation we are developing to meet these requirements
Limits on the ultra-bright Fast Radio Burst population from the CHIME Pathfinder
We present results from a new incoherent-beam Fast Radio Burst (FRB) search
on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder. Its
large instantaneous field of view (FoV) and relative thermal insensitivity
allow us to probe the ultra-bright tail of the FRB distribution, and to test a
recent claim that this distribution's slope, , is quite small. A 256-input incoherent beamformer was
deployed on the CHIME Pathfinder for this purpose. If the FRB distribution were
described by a single power-law with , we would expect an FRB
detection every few days, making this the fastest survey on sky at present. We
collected 1268 hours of data, amounting to one of the largest exposures of any
FRB survey, with over 2.4\,\,10\,deg\,hrs. Having seen no
bursts, we have constrained the rate of extremely bright events to
\,sky\,day above \,220 Jy\,ms
for between 1.3 and 100\,ms, at 400--800\,MHz. The non-detection also
allows us to rule out with 95 confidence, after
marginalizing over uncertainties in the GBT rate at 700--900\,MHz, though we
show that for a cosmological population and a large dynamic range in flux
density, is brightness-dependent. Since FRBs now extend to large
enough distances that non-Euclidean effects are significant, there is still
expected to be a dearth of faint events and relative excess of bright events.
Nevertheless we have constrained the allowed number of ultra-intense FRBs.
While this does not have significant implications for deeper, large-FoV surveys
like full CHIME and APERTIF, it does have important consequences for other
wide-field, small dish experiments
Characterization of the John A. Galt telescope for radio holography with CHIME
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) will measure the
21 cm emission of astrophysical neutral hydrogen to probe large scale structure
at redshifts z=0.8-2.5. However, detecting the 21 cm signal beneath
substantially brighter foregrounds remains a key challenge. Due to the high
dynamic range between 21 cm and foreground emission, an exquisite calibration
of instrument systematics, notably the telescope beam, is required to
successfully filter out the foregrounds. One technique being used to achieve a
high fidelity measurement of the CHIME beam is radio holography, wherein
signals from each of CHIME's analog inputs are correlated with the signal from
a co-located reference antenna, the 26 m John A. Galt telescope, as the 26 m
Galt telescope tracks a bright point source transiting over CHIME. In this work
we present an analysis of several of the Galt telescope's properties. We employ
driftscan measurements of several bright sources, along with background
estimates derived from the 408 MHz Haslam map, to estimate the Galt system
temperature. To determine the Galt telescope's beam shape, we perform and
analyze a raster scan of the bright radio source Cassiopeia A. Finally, we use
early holographic measurements to measure the Galt telescope's geometry with
respect to CHIME for the holographic analysis of the CHIME and Galt
interferometric data set
An Injection System for the CHIME/FRB Experiment
Dedicated surveys searching for Fast Radio Bursts (FRBs) are subject to
selection effects which bias the observed population of events. Software
injection systems are one method of correcting for these biases by injecting a
mock population of synthetic FRBs directly into the realtime search pipeline.
The injected population may then be used to map intrinsic burst properties onto
an expected signal-to-noise ratio (SNR), so long as telescope characteristics
such as the beam model and calibration factors are properly accounted for. This
paper presents an injection system developed for the Canadian Hydrogen
Intensity Mapping Experiment Fast Radio Burst project (CHIME/FRB). The system
was tested to ensure high detection efficiency, and the pulse calibration
method was verified. Using an injection population of ~85,000 synthetic FRBs,
we found that the correlation between fluence and SNR for injected FRBs was
consistent with that of CHIME/FRB detections in the first CHIME/FRB catalog. We
also noted that the sensitivity of the telescope varied strongly as a function
of the broadened burst width, but not as a function of the dispersion measure.
We conclude that some of the machine-learning based Radio Frequency
Interference (RFI) mitigation methods used by CHIME/FRB can be re-trained using
injection data to increase sensitivity to wide events, and that planned
upgrades to the presented injection system will allow for determining a more
accurate CHIME/FRB selection function in the near future.Comment: 13 pages, 8 figures. Submitted to A
A Detection of Cosmological 21 cm Emission from CHIME in Cross-correlation with eBOSS Measurements of the Lyman- Forest
We report the detection of 21 cm emission at an average redshift in the cross-correlation of data from the Canadian Hydrogen Intensity
Mapping Experiment (CHIME) with measurements of the Lyman- forest from
eBOSS. Data collected by CHIME over 88 days in the ~MHz frequency band
() are formed into maps of the sky and high-pass delay filtered
to suppress the foreground power, corresponding to removing cosmological scales
with at the average redshift.
Line-of-sight spectra to the eBOSS background quasar locations are extracted
from the CHIME maps and combined with the Lyman- forest flux
transmission spectra to estimate the 21 cm-Lyman- cross-correlation
function. Fitting a simulation-derived template function to this measurement
results in a detection significance. The coherent accumulation of the
signal through cross-correlation is sufficient to enable a detection despite
excess variance from foreground residuals times brighter than the
expected thermal noise level in the correlation function. These results are the
highest-redshift measurement of \tcm emission to date, and set the stage for
future 21 cm intensity mapping analyses at
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