99 research outputs found
Large scale distribution of total mass versus luminous matter from Baryon Acoustic Oscillations: First search in the SDSS-III BOSS Data Release 10
Baryon Acoustic Oscillations (BAOs) in the early Universe are predicted to
leave an as yet undetected signature on the relative clustering of total mass
versus luminous matter. A detection of this effect would provide an important
confirmation of the standard cosmological paradigm and constrain alternatives
to dark matter as well as non-standard fluctuations such as Compensated
Isocurvature Perturbations (CIPs). We conduct the first observational search
for this effect, by comparing the number-weighted and luminosity-weighted
correlation functions, using the SDSS-III BOSS Data Release 10 CMASS sample.
When including CIPs in our model, we formally obtain evidence at of
the relative clustering signature and a limit that matches the existing upper
limits on the amplitude of CIPs. However, various tests suggest that these
results are not yet robust, perhaps due to systematic biases in the data. The
method developed in this Letter, used with more accurate future data such as
that from DESI, is likely to confirm or disprove our preliminary evidence.Comment: 6 pages, 2 figures, accepted for publication in PR
PREVALENCE AND CHARACTERIZATION OF LISTERIA MONOCYTOGENES ISOLATED FROM DIFFERENT FOOD PRODUCTS
During the period 2006-2009, 453 samples of various food products were collected and analyzed for Listeria monocytogenes. In order to increase the knowledge of the ecology and epidemiology of this organism, isolates were characterized by serotyping, and PCR for the presence of the main virulence-associated genes and genetic relatedness
Scale Dependence of Halo Bispectrum from Non-Gaussian Initial Conditions in Cosmological N-body Simulations
We study the halo bispectrum from non-Gaussian initial conditions. Based on a
set of large -body simulations starting from initial density fields with
local type non-Gaussianity, we find that the halo bispectrum exhibits a strong
dependence on the shape and scale of Fourier space triangles near squeezed
configurations at large scales. The amplitude of the halo bispectrum roughly
scales as . The resultant scaling on the triangular shape is consistent
with that predicted by Jeong & Komatsu based on perturbation theory. We
systematically investigate this dependence with varying redshifts and halo mass
thresholds. It is shown that the dependence of the halo bispectrum is
stronger for more massive haloes at higher redshifts. This feature can be a
useful discriminator of inflation scenarios in future deep and wide galaxy
redshift surveys.Comment: 27 pages, 10 figures; revised argument in section 6, added appendix
C, JCAP accepted versio
Statistical Determination of Bulk Flow Motions
We present here a new parameterization for the bulk motions of galaxies and
clusters (in the linear regime) that can be measured statistically from the
shape and amplitude of the two-dimensional two-point correlation function. We
further propose the one-dimensional velocity dispersion (v_p) of the bulk flow
as a complementary measure of redshift-space distortions, which is
model-independent and not dependent on the normalisation method. As a
demonstration, we have applied our new methodology to the C4 cluster catalogue
constructed from Data Release Three (DR3) of the Sloan Digital Sky Survey. We
find v_p=270^{+433}km/s (also consistent with v_p=0) for this cluster sample
(at z=0.1), which is in agreement with that predicted for a WMAP5-normalised
LCDM model (i.e., v_p(LCDM=203km/s). This measurement does not lend support to
recent claims of excessive bulk motions (\simeq1000 km/s) which appear in
conflict with LCDM, although our large statistical error cannot rule them out.
From the measured coherent evolution of v_p, we develop a technique to
re-construct the perturbed potential, as well as estimating the unbiased matter
density fluctuations and scale--independent bias.Comment: 8 pages, 5 figure
A new Low Gain Avalanche Diode concept: the double-LGAD
This paper describes the new concept of the double-LGAD. The goal is to
increase the charge at the input of the electronics, keeping a time resolution
equal or better than a standard (single) LGAD; this has been realized by adding
the charges of two coupled LGADs while still using a single front-end
electronics. The study here reported has been done starting from single LGAD
with a thickness of 25 \textmu{m}, 35 \textmu{m} and 50 \textmu{m}.Comment: arXiv admin note: text overlap with arXiv:2208.0571
Brittle asthma a report of 2 cases
Brittle asthma, even though it is thought to be a rare form of Asthma, may form the bulk of our difficult to treat asthma and frequently unresponsive exacerbation. Brittle Asthma. Brittle asthma is a rare form of severe asthma characterized by a wide variation of Peak Expiratory Flow (PEF)1, in spite of high doses of inhaled steroids and bronchodilator therapy. Brittle asthmatic patients have very serious and often, life threatening, attacks. There are two forms of brittle asthma.Case PresentationWe present the cases of a 45yr old Nurse anesthetics who was diagnosed >5yrs ago and a 56yr old unemployed who was diagnosed >15yrs ago. Both have been stable for years on add on maintenance therapy with high doses of inhaled corticosteroid and β2 agonist as oral salbutamol and an inhaler therapy during exacerbation. Recently, both patients noticed worsening of symptoms despite high dose therapy, They have been in and out of hospital recently for uncontrolled asthma. They later had to be admitted in ICU because of respiratory insufficiency. These two lapsed into brittle asthma with recurrent bronchospasm, due to repeated to anesthetic agents and environmental exposure at home respectively.Keywords: Brittle Asthma, Peak Expiratory Flow (PEF), Respiratory Insufficiency, environmental exposur
First results on monolithic CMOS detector with internal gain
: In this paper we report on a set of characterisations carried out on the first monolithic
LGAD prototype integrated in a customised 110 nm CMOS process having a depleted active volume
thickness of 48 μm. This prototype is formed by a pixel array where each pixel has a total size of
100 μm × 250 μm and includes a high-speed front-end amplifier. After describing the sensor and
the electronics architecture, both laboratory and in-beam measurements are reported and described. Optical characterisations performed with an IR pulsed laser setup have shown a sensor internal gain of
about 2.5. With the same experimental setup, the electronic jitter was found to be between 50 ps and
150 ps, depending on the signal amplitude. Moreover, the analysis of a test beam performed at the
Proton Synchrotron (PS) T10 facility of CERN with 10 GeV/c protons and pions indicated that the
overall detector time resolution is in the range of 234 ps to 244 ps. Further TCAD investigations, based
on the doping profile extracted from C(V) measurements, confirmed the multiplication gain measured
on the test devices. Finally, TCAD simulations were used to tune the future doping concentration of
the gain layer implant, targeting sensors with a higher avalanche gain. This adjustment is expected
to enhance the timing performance of the sensors of the future productions, in order to cope with
the high event rate expected in most of the near future high-energy and high-luminosity physics
experiments, where the time resolution will be essential to disentangle overlapping events and it
will also be crucial for Particle IDentification (PID
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples
We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance Λ cold dark matter (ΛCDM) cosmological model, the DR11 sample covers a volume of 13 Gpc3 and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the BAO feature. The acoustic features are detected at a significance of over 7σ in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, rd, which has a value of rd,fid = 149.28 Mpc in our fiducial cosmology. We find DV = (1264 ± 25 Mpc)(rd/rd,fid) at z = 0.32 and DV = (2056 ± 20 Mpc)(rd/rd,fid) at z = 0.57. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line of sight yields measurements at z = 0.57 of DA = (1421 ± 20 Mpc)(rd/rd,fid) and H = (96.8 ± 3.4 km s−1 Mpc−1)(rd,fid/rd). Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat CDM model with a cosmological constant.Publisher PDFPeer reviewe
Measurements of the Cherenkov effect in direct detection of charged particles with SiPMs
In this paper, different Silicon PhotoMultiplier (SiPM) sensors have been
tested with charged particles to characterize the Cherenkov light produced in
the sensor protection layer. A careful position scan of the SiPM response has
been performed with different prototypes, confirming the large number of firing
cells and proving almost full efficiency, with the SiPM filling factor
essentially negligible. This study also allowed us to study the time resolution
of such devices as a function of the number of firing cells, reaching values
below 20 ps. These measurements provide significant insight into the
capabilities of SiPM sensors in direct detection of charged particles and their
potential for several applications
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