94 research outputs found
Frequency and surface dependence of the mechanical loss in fused silica
We have compiled measurements of the mechanical loss in fused silica from
samples spanning a wide range of geometries and resonant frequency in order to
model the known variation of the loss with frequency and surface-to-volume
ratio. This improved understanding of the mechanical loss has contributed
significantly to the design of advanced interferometric gravitational wave
detectors, which require ultra-low loss materials for their test mass mirrors.Comment: 5 pages, 3 figure but 5 figure file
Systematic measurement of the intrinsic losses in various kinds of bulk fused silica
We systematically measured and compared the mechanical losses of various
kinds of bulk fused silica. Their quality factors ranged widely from 7x10^5 to
4x10^7, the latter being one of the highest reported among bulk fused silica.
We observed frequency-dependent losses and a decrease in the losses upon
annealing.Comment: 14 pages, 4 figures, Submitted to Phys. Lett.
Formation of a transdisciplinary community of practice in rural areas, with an interactive database of co-created knowledge: A case study in Noto, Japan
Many rural areas suffer from severe depopulation, and the absence of a university is one reason for outmigration. Where research and education are valued, however, such rural areas can attract scholars and students visiting from universities and other external institutions. Scholarly outputs of research, such as research articles and project reports, particularly those from community-based research (CBR), can themselves become an asset for use by local communities. We consider that CBR can contribute to asset-based community development (ABCD) when a transdisciplinary community of practice (TDCOP) emerges and drives the processes of collaborative creation and use of the knowledge. A particularly critical mechanism, which is currently lacking, is to allow the local community to collect knowledge outputs and make them easily available to interested actors within and outside of the community. We assume that a core tool in this mechanism is an interactive database. It can be equipped with a user interface, allowing enjoyable and active searches, and possibly a mechanism by which users themselves can contribute to gradual development of the database. We formed a study group of researchers and practitioners to conduct a case study in the Noto region of Japan. We identified the existing assets in Noto, including the knowledge created through CBR, and then collected and shared our own experiences and practices, as well as lessons learned from other regions in Japan, to explore the principles of designing a database. A CBR database should not only be a static inventory of past research, but also capable of facilitating new cycles of knowledge co-creation. With a comprehensive and easily accessible inventory of knowledge in place, we conclude that there is high potential in enabling CBR itself to be an asset, which can help achieve ABCD in rural communities
Optimizing Nervous System-Specific Gene Targeting with Cre Driver Lines: Prevalence of Germline Recombination and Influencing Factors.
The Cre-loxP system is invaluable for spatial and temporal control of gene knockout, knockin, and reporter expression in the mouse nervous system. However, we report varying probabilities of unexpected germline recombination in distinct Cre driver lines designed for nervous system-specific recombination. Selective maternal or paternal germline recombination is showcased with sample Cre lines. Collated data reveal germline recombination in over half of 64 commonly used Cre driver lines, in most cases with a parental sex bias related to Cre expression in sperm or oocytes. Slight differences among Cre driver lines utilizing common transcriptional control elements affect germline recombination rates. Specific target loci demonstrated differential recombination; thus, reporters are not reliable proxies for another locus of interest. Similar principles apply to other recombinase systems and other genetically targeted organisms. We hereby draw attention to the prevalence of germline recombination and provide guidelines to inform future research for the neuroscience and broader molecular genetics communities
Coincidence analysis to search for inspiraling compact binaries using TAMA300 and LISM data
Japanese laser interferometric gravitational wave detectors, TAMA300 and
LISM, performed a coincident observation during 2001. We perform a coincidence
analysis to search for inspiraling compact binaries. The length of data used
for the coincidence analysis is 275 hours when both TAMA300 and LISM detectors
are operated simultaneously. TAMA300 and LISM data are analyzed by matched
filtering, and candidates for gravitational wave events are obtained. If there
is a true gravitational wave signal, it should appear in both data of detectors
with consistent waveforms characterized by masses of stars, amplitude of the
signal, the coalescence time and so on. We introduce a set of coincidence
conditions of the parameters, and search for coincident events. This procedure
reduces the number of fake events considerably, by a factor
compared with the number of fake events in single detector analysis. We find
that the number of events after imposing the coincidence conditions is
consistent with the number of accidental coincidences produced purely by noise.
We thus find no evidence of gravitational wave signals. We obtain an upper
limit of 0.046 /hours (CL ) to the Galactic event rate within 1kpc from
the Earth. The method used in this paper can be applied straightforwardly to
the case of coincidence observations with more than two detectors with
arbitrary arm directions.Comment: 28 pages, 17 figures, Replaced with the version to be published in
Physical Review
Results of the search for inspiraling compact star binaries from TAMA300's observation in 2000-2004
We analyze the data of TAMA300 detector to search for gravitational waves
from inspiraling compact star binaries with masses of the component stars in
the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the
years 2000-2004, are used for the event search. We combine the results of
different observation runs, and obtained a single upper limit on the rate of
the coalescence of compact binaries in our Galaxy of 20 per year at a 90%
confidence level. In this upper limit, the effect of various systematic errors
such like the uncertainty of the background estimation and the calibration of
the detector's sensitivity are included.Comment: 8 pages, 4 Postscript figures, uses revtex4.sty The author list was
correcte
Observation results by the TAMA300 detector on gravitational wave bursts from stellar-core collapses
We present data-analysis schemes and results of observations with the TAMA300
gravitational-wave detector, targeting burst signals from stellar-core collapse
events. In analyses for burst gravitational waves, the detection and
fake-reduction schemes are different from well-investigated ones for a
chirp-wave analysis, because precise waveform templates are not available. We
used an excess-power filter for the extraction of gravitational-wave
candidates, and developed two methods for the reduction of fake events caused
by non-stationary noises of the detector. These analysis schemes were applied
to real data from the TAMA300 interferometric gravitational wave detector. As a
result, fake events were reduced by a factor of about 1000 in the best cases.
The resultant event candidates were interpreted from an astronomical viewpoint.
We set an upper limit of 2.2x10^3 events/sec on the burst gravitational-wave
event rate in our Galaxy with a confidence level of 90%. This work sets a
milestone and prospects on the search for burst gravitational waves, by
establishing an analysis scheme for the observation data from an
interferometric gravitational wave detector
Stable Operation of a 300-m Laser Interferometer with Sufficient Sensitivity to Detect Gravitational-Wave Events within our Galaxy
TAMA300, an interferometric gravitational-wave detector with 300-m baseline
length, has been developed and operated with sufficient sensitivity to detect
gravitational-wave events within our galaxy and sufficient stability for
observations; the interferometer was operated for over 10 hours stably and
continuously. With a strain-equivalent noise level of , a signal-to-noise ratio (SNR) of 30 is expected for
gravitational waves generated by a coalescence of 1.4 -1.4
binary neutron stars at 10 kpc distance. %In addition, almost all noise sources
which limit the sensitivity and which %disturb the stable operation have been
identified. We evaluated the stability of the detector sensitivity with a
2-week data-taking run, collecting 160 hours of data to be analyzed in the
search for gravitational waves.Comment: 5 pages, 4 figure
- …