3,639 research outputs found
Detection of liquid xenon scintillation light with a Silicon Photomultiplier
We have studied the feasibility of a silicon photomultiplier (SiPM) to detect
liquid xenon (LXe) scintillation light. The SiPM was operated inside a small
volume of pure LXe, at -95 degree Celsius, irradiated with an internal Am-241
alpha source. The gain of the SiPM at this temperature was estimated to be 1.8
x 10^6 with bias voltage at 52 V. Based on the geometry of the setup, the
quantum efficiency of the SiPM was estimated to be 22% at the Xe wavelength of
178 nm. The low excess noise factor, high single photoelectron detection
efficiency, and low bias voltage of SiPMs make them attractive alternative UV
photon detection devices to photomultiplier tubes (PMTs) for liquid xenon
detectors, especially for experiments requiring a very low energy detection
threshold, such as neutralino dark matter searches
Suppression of 12-O-tetradecanoylphorbol-13-acetate-induced ornithine decarboxylase activity by resveratrol derivatives
As demonstrated previously, resveratrol (3,4',5-trihydroxy-trans-stilbene) inhibits 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ornithine decarboxylase (ODC), the key rate limiting enzyme in mammalian polyamine synthesis. Using human bladder epithelial carcinoma HTB-24 cells in culture where resveratrol inhibits induction with an IC50 of 8.8 µM, we now report potential metabolites demonstrate greater activity [tetrabutylammonium (E)-4-(3,5-dihydroxystyryl)phenyl sulfate (IC50 1.2 µM), resveratrol tripotassium 3,5,4'-trisulfate (IC50 1.8 µM), resveratrol tripotassium 3,4'-disulfate (IC50 1.8 µM), and resveratrol tripotassium 3,5-disulfate (IC50 2.3 µM)]. Based on RT-PCR studies, ODC inhibition occurs at the transcriptional level, but this was not due to direct inhibition of protein kinase C (e.g., resveratrol IC50, 79 µM; resveratrol tripotassium 3,5-disulfate IC50, 49 µM). Additional work is underway to more fully investigate this potentially important observation. [This work was supported by program project P01 CA48112 awarded by the National Cancer Institute. SL acknowledges Indo-US Science and Technology Forum (IUSSTF), New Delhi for a Research Fellowship]
Tips for New Horse Owners
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Horses can be kept at a person’s own place or boarded at a commercial stable. Keeping a horse on a person’s acreage provides more management control, saves time and expenses, and can reduce the risk of injuries and disease. Most importantly, it allows fuller enjoyment and greater learning-experiences. However, it also requires more management, knowledge, and time. Remember, horses must be cared for daily
Adiabatically coupled systems and fractional monodromy
We present a 1-parameter family of systems with fractional monodromy and
adiabatic separation of motion. We relate the presence of monodromy to a
redistribution of states both in the quantum and semi-quantum spectrum. We show
how the fractional monodromy arises from the non diagonal action of the
dynamical symmetry of the system and manifests itself as a generic property of
an important subclass of adiabatically coupled systems
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