5,364 research outputs found
Association of tumor satellite distance with prognosis and contra-lateral neck recurrence of tongue squamous cell carcinoma.
No full textLigation of the internal maxillary artery to reduce the intraoperative bleeding during total maxillectomy
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Sensitivities for coherent elastic scattering of solar and supernova neutrinos with future NaI(Tl) dark matter search detectors of COSINE-200/1T
Full text linkWe investigate the prospects for measuring the coherent elastic
neutrino-nucleus scattering of solar and supernova neutrinos in future NaI(Tl)
dark matter detection experiments. Considering the reduced background and
improved light yield of the recently developed NaI(Tl) crystals, more than
3 observation sensitivities of the supernova neutrino within the Milky
Way are demonstrated. In the case of the solar neutrino, approximately 3
observations are marginal with a 1 ton NaI(Tl) experiment assuming an order of
magnitude reduced background, five photoelectron thresholds, and 5-year data
exposure
Improving the light collection using a new NaI(Tl) crystal encapsulation
No full text© 2020 Elsevier B.V. NaI(Tl) crystals are used as particle detectors in a variety of rare-event search experiments because of their superb light-emission quality. The crystal light yield is generally high, above 10 photoelectrons per keV, and its emission spectrum is peaked around 400 nm, which matches well to the sensitive region of bialkali photocathode photomultiplier tubes. However, since NaI(Tl) crystals are hygroscopic, a sophisticated method of encapsulation has to be applied that prevents moisture from chemically attacking the crystal and thereby degrading the emission. In addition, operation with low energy thresholds, which is essential for a number of new phenomenon searches, is usually limited by the crystal light yield; in these cases higher light yields can translate into lower thresholds that improve the experimental sensitivity. Here we describe the development of an encapsulation technique that simplifies the overall design by attaching the photo sensors directly to the crystal so that light losses are minimized. The light yield of a NaI(Tl) crystal encapsulated with this technique was improved by more than 30%, and as many as 22 photoelectrons per keV have been measured. Consequently, the energy threshold can be lowered and the energy resolution improved. Detectors with this higher light yield are sensitive to events with sub-keV energies and well suited for low-mass dark matter particle searches and measurements of neutrino-nucleus coherent scattering11Nsciescopu
Evaluation of KO-Tab 1-2-3: a wash-resistant 'dip-it-yourself' insecticide formulation for long-lasting treatment of mosquito nets.
Full text linkINTRODUCTION: Insecticide-treated nets (ITN) are an important method of preventing malaria. To remain effective, they need to be re-treated with pyrethroid insecticide at approximately yearly intervals. Systems for re-treating nets in Africa are limited, and the vast majority of nets in use have never been treated or were treated only once. Bayer Environmental Science (BES) has developed a long-lasting formulation 'KO-Tab 1-2-3' which can be applied to the net post-manufacture, under field conditions, and renders the insecticide wash-resistant. METHODS: The performance of polyester nets treated with three kinds of BES long-lasting formulations, a conventional ITN (treated with standard KO-Tab) and PermaNet 2.0 were evaluated after washing samples of treated netting up to 30 times using standard WHO procedures. Performance was measured using 'three-minute exposure' and 'median time to knockdown' bioassay tests and by measuring the levels of deltamethrin using high-pressure liquid chromatography. RESULTS: The conventional ITN was largely stripped of deltamethrin within 5-10 washes and insecticidal efficacy in bioassay declined to suboptimal levels. With PermaNet and KO-Tab 1-2-3 the loss of deltamethrin was much slower: insecticide content halved within 20 washes and there was no loss of biological efficacy in three-minute exposure bioassays in WHO cylinders even after 30 washes. After 30 washes there remained on the netting 16% (4.4 mg/m2) of the loading dose of KO-Tab 1-2-3 and 28% (18.8 mg/m2) of the loading dose of PermaNet. CONCLUSION: KO-Tab 1-2-3 was confirmed to be a long-lasting insecticide formulation. This finding raises the prospect of conventional polyester nets being converted into long-lasting insecticidal nets through simple dipping in the community or at home. This single development, if widely adopted, could transform the malaria control landscape in Africa and have a major impact on malaria
Limits on interactions between weakly interacting massive particles and nucleons obtained with NaI(Tl) crystal detectors
No full textLimits on the cross section for weakly interacting massive particles (WIMPs) elastic scattering on nuclei in NaI(Tl) detectors at the Yangyang Underground Laboratory are obtained from a 2967.4 kg·day data exposure. The nuclei recoiling from the scattering process are identified by the pulse shape of the scintillation light signals that they produce. The data are consistent with a no nuclear-recoil hypothesis, and WIMP-mass-dependent 90% confidence-level upper-limits are set on WIMP-nuclei elastic scattering cross sections. These limits partially exclude the DAMA/LIBRA allowed region for WIMP-sodium interactions with the same NaI(Tl) target material. The 90% confidence level upper limit on the WIMP-nucleon spin-independent cross section is 3.26×10 −4 pb for a WIMP mass of 10 GeV/c 2 . © 2019, The Author(s)11Nsciescopu
Tangle-bearing neurons survive despite disruption of membrane integrity in a mouse model of tauopathy
Full text linkNeurofibrillary tangles (NFTs) are associated with neuronal loss and correlate with cognitive impairment in Alzheimer disease, but how NFTs relate to neuronal death is not clear. We studied cell death in Tg4510 mice that reversibly express P301L mutant human tau and accumulate NFTs using in vivo multiphoton imaging of neurofibrillary pathology, propidium iodide (PI) incorporation into cells, caspase activation, and DNA labeling. We first observed that in live mice, a minority of neurons were labeled with the caspase probe or with PI fluorescence. These markers of cell stress were localized in the same cells and appeared specifically within NFT-bearing neurons. Contrary to expectations, the PI-stained neurons did not die during a day of observation; the presence of Hoechst-positive nuclei in them on the subsequent day indicated that the NFT-associated membrane disruption, as suggested by PI staining, and caspase activation do not lead to immediate death of neurons in this tauopathy model. This unique combination of in vivo multiphoton imaging with markers of cell death and pathological alteration is a powerful tool for investigating neuronal damage associated with neurofibrillary pathology
Development of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment
No full textThe annual modulation signal observed by the DAMA experiment is a long-standing question in the community of dark matter direct detection. This necessitates an independent verification of its existence using the same detection technique. The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors providing interesting checks on the DAMA signal. However, due to higher backgrounds in the NaI(Tl) crystals used in COSINE-100 relative to those used for DAMA, it was difficult to reach final conclusions. Since the start of COSINE-100 data taking in 2016, we also have initiated a program to develop ultra-pure NaI(Tl) crystals for COSINE-200, the next phase of the experiment. The program includes efforts of raw powder purification, ultra-pure NaI(Tl) crystal growth, and detector assembly techniques. After extensive research and development of NaI(Tl) crystal growth, we have successfully grown a few small-size (0.61–0.78 kg) thallium-doped crystals with high radio-purity. A high light yield has been achieved by improvements of our detector assembly technique. Here we report the ultra-pure NaI(Tl) detector developments at the Institute for Basic Science, Korea. The technique developed here will be applied to the production of NaI(Tl) detectors for the COSINE-200 experiment
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