68 research outputs found
Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector
A large heat load caused by thermal radiation through a metal shield pipe was
observed in a cooling test of a cryostat for a prototype of a cryogenic
interferometric gravitational wave detector. The heat load was approximately
1000 times larger than the value calculated by the Stefan-Boltzmann law. We
studied this phenomenon by simulation and experiment and found that it was
caused by the conduction of thermal radiation in a metal shield pipe.Comment: 7 pages, 4 figures, 2 tables, Submitted to Jpn. J. Appl. Phy
Estimation of Newtonian noise from KAGRA cooling system
KAGRA is the first km-scale gravitational wave detector to be constructed
underground and employ cryogenics to cool down its test masses. While the
underground location provides a quiet site with low seismic noise, the cooling
infrastructure is known to generate large mechanical vibrations due to
cryocooler operation and structural resonances of the cryostat. As cooling
system components are relatively heavy and in close proximity to the test
masses, oscillation of gravity force induced by their vibration, so-called
Newtonian noise, could contaminate the detector sensitivity. In this paper, we
use the results from vibration analysis of the KAGRA cryostat to estimate
cooling system Newtonian noise in the 1-100 Hz frequency band. Our calculations
show that, while this noise does not limit the current detector sensitivity or
inspiral range, it will be an issue in the future when KAGRA improves its
sensitivity. We conclude that KAGRA may need to implement Wiener filters to
subtract this noise in the future
Multiplex Polymerase Chain Reaction Assay for Early Diagnosis of Viral Infection
Viral reactivation is one of the most serious complications for immunocompromised patients. Under immunosuppressive conditions, some viruses can be reactivated solely or simultaneously and may thus cause life-threatening infection. Therefore, the prompt and proper diagnosis of viral reactivation is important for the initiation of preemptive therapy. For this purpose, we recently developed a multiplex-virus polymerase chain reaction (PCR) assay. The multiplex PCR assay is designed to qualitatively measure the genomic DNA of 12 viruses at once: cytomegalovirus (CMV), human herpesvirus type 6 (HHV-6), HHV-7, HHV-8, Epstein-Barr virus (EBV), varicella-zoster virus (VZV), BK virus (BKV), JC virus (JCV), parvovirus B19 (ParvoB19), herpes simplex virus type 1 (HSV-1), HSV-2, and hepatitis B virus (HBV). When a specific PCR signal is obtained, the viral load is determined by a quantitative real-time PCR. The qualitative multiplex and quantitative real-time PCR procedures take only 3 hours to complete. With this assay system, we can identify viremia at the early stage and thereby prevent it from progressing to overt and symptomatic viral infection in immunocompromised patients, such as those receiving hematopoietic stem cell transplantation
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