1,204 research outputs found
Use of a Granulocyte Immunofluorescence Assay Designed for Humans for Detection of Antineutrophil Cytoplasmic Antibodies in Dogs with Chronic Enteropathies
Perinuclear antineutrophil cytoplasmic antibodies (pANCA) previously have been shown to be serum markers in dogs with chronic enteropathies, with dogs that have foodâresponsive disease (FRD) having higher frequencies of seropositivity than dogs with steroidâresponsive disease (SRD). The indirect immunofluorescence (IIF) assay used in previous publications is timeâconsuming to perform, with low interobserver agreement. Fortyâfour dogs with FRD, 20 dogs with SRD, 20 control dogs, and 38 softâcoated wheaten terrier (SCWT) or SCWTâcross dogs
High power and ultra-low-noise photodetector for squeezed-light enhanced gravitational wave detectors
Current laser-interferometric gravitational wave detectors employ a self-homodyne
readout scheme where a comparatively large light power (5â50 mW) is detected per photosensitive
element. For best sensitivity to gravitational waves, signal levels as low as the quantum
shot noise have to be measured as accurately as possible. The electronic noise of the detection
circuit can produce a relevant limit to this accuracy, in particular when squeezed states of light
are used to reduce the quantum noise. We present a new electronic circuit design reducing the
electronic noise of the photodetection circuit in the audio band. In the application of this circuit at
the gravitational-wave detector GEO 600 the shot-noise to electronic noise ratio was permanently
improved by a factor of more than 4 above 1 kHz, while the dynamic range was improved by
a factor of 7. The noise equivalent photocurrent of the implemented photodetector and circuit
is about 5 ”A/
â\ud
Hz above 1 kHz with a maximum detectable photocurrent of 20 mA. With the
new circuit, the observed squeezing level in GEO 600 increased by 0.2 dB. The new circuit also
creates headroom for higher laser power and more squeezing to be observed in the future in
GEO 600 and is applicable to other optics experiments
GEO 600 and the GEO-HF upgrade program: successes and challenges
The German-British laser-interferometric gravitational wave detector GEO 600
is in its 14th year of operation since its first lock in 2001. After GEO 600
participated in science runs with other first-generation detectors, a program
known as GEO-HF began in 2009. The goal was to improve the detector sensitivity
at high frequencies, around 1 kHz and above, with technologically advanced yet
minimally invasive upgrades. Simultaneously, the detector would record science
quality data in between commissioning activities. As of early 2014, all of the
planned upgrades have been carried out and sensitivity improvements of up to a
factor of four at the high-frequency end of the observation band have been
achieved. Besides science data collection, an experimental program is ongoing
with the goal to further improve the sensitivity and evaluate future detector
technologies. We summarize the results of the GEO-HF program to date and
discuss its successes and challenges
Cost-benefit analysis for commissioning decisions in GEO600
Gravitational wave interferometers are complex instruments, requiring years
of commissioning to achieve the required sensitivities for the detection of
gravitational waves, of order 10^-21 in dimensionless detector strain, in the
tens of Hz to several kHz frequency band. Investigations carried out by the
GEO600 detector characterisation group have shown that detector
characterisation techniques are useful when planning for commissioning work. At
the time of writing, GEO600 is the only large scale laser interferometer
currently in operation running with a high duty factor, 70%, limited chiefly by
the time spent commissioning the detector. The number of observable
gravitational wave sources scales as the product of the volume of space to
which the detector is sensitive and the observation time, so the goal of
commissioning is to improve the detector sensitivity with the least possible
detector down time. We demonstrate a method for increasing the number of
sources observable by such a detector, by assessing the severity of
non-astrophysical noise contaminations to efficiently guide commissioning. This
method will be particularly useful in the early stages and during the initial
science runs of the aLIGO and adVirgo detectors, as they are brought up to
design performance.Comment: 17 pages, 17 figures, 2 table
The upgrade of GEO600
The German / British gravitational wave detector GEO 600 is in the process of
being upgraded. The upgrading process of GEO 600, called GEO-HF, will
concentrate on the improvement of the sensitivity for high frequency signals
and the demonstration of advanced technologies. In the years 2009 to 2011 the
detector will undergo a series of upgrade steps, which are described in this
paper.Comment: 9 pages, Amaldi 8 conference contributio
The upgrade of GEO 600
The German/ British gravitational wave detector GEO 600 is in the process of being upgraded. The upgrading process of GEO 600, called GEO-HF, will concentrate on the improvement of the sensitivity for high frequency signals and the demonstration of advanced technologies. In the years 2009 to 2011 the detector will undergo a series of upgrade steps, which are described in this paper.Science and Technology Facilities Council (STFC)BMBFMax Planck Society (MPG)State of Lower SaxonyDFG/SFB/Transregio
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