1,564 research outputs found
Detection of colistin resistance in Salmonella enterica using MALDIxin test on the routine MALDI Biotyper Sirius mass spectrometer
Resistance to polymyxins in most Gram-negative bacteria arises from chemical modifications to the lipid A portion of their lipopolysaccharide (LPS) mediated by chromosomally-encoded mutations or the recently discovered plasmid-encoded mcr genes that have further complicated the landscape of colistin resistance. Currently, minimal inhibitory concentration (MIC) determination by broth microdilution, the gold standard for the detection of polymyxin resistance, is time consuming (24 hours) and challenging to perform in clinical and veterinatryveterinary laboratories. Here we present the use of the MALDIxin to detect colistin resistant Salmonella enterica using the MALDxin test on the routine matrix-assisted laser desorption ionization (MALDI) Biotyper Sirius system
Compensation of Strong Thermal Lensing in High Optical Power Cavities
In an experiment to simulate the conditions in high optical power advanced
gravitational wave detectors such as Advanced LIGO, we show that strong thermal
lenses form in accordance with predictions and that they can be compensated
using an intra-cavity compensation plate heated on its cylindrical surface. We
show that high finesse ~1400 can be achieved in cavities with internal
compensation plates, and that the cavity mode structure can be maintained by
thermal compensation. It is also shown that the measurements allow a direct
measurement of substrate optical absorption in the test mass and the
compensation plate.Comment: 8 page
Reconstruction of source location in a network of gravitational wave interferometric detectors
This paper deals with the reconstruction of the direction of a gravitational
wave source using the detection made by a network of interferometric detectors,
mainly the LIGO and Virgo detectors. We suppose that an event has been seen in
coincidence using a filter applied on the three detector data streams. Using
the arrival time (and its associated error) of the gravitational signal in each
detector, the direction of the source in the sky is computed using a chi^2
minimization technique. For reasonably large signals (SNR>4.5 in all
detectors), the mean angular error between the real location and the
reconstructed one is about 1 degree. We also investigate the effect of the
network geometry assuming the same angular response for all interferometric
detectors. It appears that the reconstruction quality is not uniform over the
sky and is degraded when the source approaches the plane defined by the three
detectors. Adding at least one other detector to the LIGO-Virgo network reduces
the blind regions and in the case of 6 detectors, a precision less than 1
degree on the source direction can be reached for 99% of the sky.Comment: Accepted in Phys. Rev.
A First Comparison Between LIGO and Virgo Inspiral Search Pipelines
This article reports on a project that is the first step the LIGO Scientific
Collaboration and the Virgo Collaboration have taken to prepare for the mutual
search for inspiral signals. The project involved comparing the analysis
pipelines of the two collaborations on data sets prepared by both sides,
containing simulated noise and injected events. The ability of the pipelines to
detect the injected events was checked, and a first comparison of how the
parameters of the events were recovered has been completed.Comment: GWDAW-9 proceeding
A first comparison of search methods for gravitational wave bursts using LIGO and Virgo simulated data
We present a comparative study of 6 search methods for gravitational wave
bursts using simulated LIGO and Virgo noise data. The data's spectra were
chosen to follow the design sensitivity of the two 4km LIGO interferometers and
the 3km Virgo interferometer. The searches were applied on replicas of the data
sets to which 8 different signals were injected. Three figures of merit were
employed in this analysis: (a) Receiver Operator Characteristic curves, (b)
necessary signal to noise ratios for the searches to achieve 50 percent and 90
percent efficiencies, and (c) variance and bias for the estimation of the
arrival time of a gravitational wave burst.Comment: GWDAW9 proceeding
Increase in outbreaks of gastroenteritis linked to bathing water in Finland in summer 2014
Peer reviewe
A comparison of methods for gravitational wave burst searches from LIGO and Virgo
The search procedure for burst gravitational waves has been studied using 24
hours of simulated data in a network of three interferometers (Hanford 4-km,
Livingston 4-km and Virgo 3-km are the example interferometers). Several
methods to detect burst events developed in the LIGO Scientific Collaboration
(LSC) and Virgo collaboration have been studied and compared. We have performed
coincidence analysis of the triggers obtained in the different interferometers
with and without simulated signals added to the data. The benefits of having
multiple interferometers of similar sensitivity are demonstrated by comparing
the detection performance of the joint coincidence analysis with LSC and Virgo
only burst searches. Adding Virgo to the LIGO detector network can increase by
50% the detection efficiency for this search. Another advantage of a joint
LIGO-Virgo network is the ability to reconstruct the source sky position. The
reconstruction accuracy depends on the timing measurement accuracy of the
events in each interferometer, and is displayed in this paper with a fixed
source position example.Comment: LIGO-Virgo working group submitted to PR
Detection in coincidence of gravitational wave bursts with a network of interferometric detectors (I): Geometric acceptance and timing
Detecting gravitational wave bursts (characterised by short durations and
poorly modelled waveforms) requires to have coincidences between several
interferometric detectors in order to reject non-stationary noise events. As
the wave amplitude seen in a detector depends on its location with respect to
the source direction and as the signal to noise ratio of these bursts are
expected to be low, coincidences between antennas may not be so likely. This
paper investigates this question from a statistical point of view by using a
simple model of a network of detectors; it also estimates the timing precision
of a detection in an interferometer which is an important issue for the
reconstruction of the source location, based on time delays.Comment: low resolution figure 1 due to file size problem
Benefits of joint LIGO -- Virgo coincidence searches for burst and inspiral signals
We examine the benefits of performing a joint LIGO--Virgo search for
transient signals. We do this by adding burst and inspiral signals to 24 hours
of simulated detector data. We find significant advantages to performing a
joint coincidence analysis, above either a LIGO only or Virgo only search.
These include an increased detection efficiency, at a fixed false alarm rate,
to both burst and inspiral events and an ability to reconstruct the sky
location of a signal.Comment: 11 pages 8 figures, Amaldi 6 proceeding
A Cross-correlation method to search for gravitational wave bursts with AURIGA and Virgo
We present a method to search for transient GWs using a network of detectors
with different spectral and directional sensitivities: the interferometer Virgo
and the bar detector AURIGA. The data analysis method is based on the
measurements of the correlated energy in the network by means of a weighted
cross-correlation. To limit the computational load, this coherent analysis step
is performed around time-frequency coincident triggers selected by an excess
power event trigger generator tuned at low thresholds. The final selection of
GW candidates is performed by a combined cut on the correlated energy and on
the significance as measured by the event trigger generator. The method has
been tested on one day of data of AURIGA and Virgo during September 2005. The
outcomes are compared to the results of a stand-alone time-frequency
coincidence search. We discuss the advantages and the limits of this approach,
in view of a possible future joint search between AURIGA and one
interferometric detector.Comment: 11 pages, 6 figures, submitted to CQG special issue for Amaldi 7
Proceeding
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