Selective production of metallic carbon nanotubes

In this report, we discuss whether the optimal electric field to promote the growth of armchair- type nanotubes (metallic character) evaluated using the previous Huckel-Poisson method can be applied at the tip of a nanotube in a realistic system. Setting the cross-section of a nanotube and the external field by the sheath, we estimate an effective area at the sheath edge. Since the electric charge distribution in a nanotube caused by the external electric field was determined in our previous study, we obtained the electric field distribution out of a nanotube by solving the Poisson equation and clarified the structure of the electric field lines. By determining the effective area, we show the optimal interval of the catalyst metal, which is necessary to selectively grow the metallic nanotubes. When nanotubes grow thickly during the initial stage of growth, a strong electric field cannot be applied to the tips of the tubes. As a tube grows and the tube length increases, we found that the optimal electric field decreased. To maintain the chemical activity at the tip, the sheath electric field must be decreased. We estimated the decreasing rate of the sheath field to the tube length.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Antimatter from supersymmetric dark matter

We propose low-energy antideuterons in cosmic rays as a new possible signature for indirect detection of supersymmetric dark matter. Since the energy spectrum of the antiproton secondary component is still spoilt by considerable theoretical uncertainties, looking for low-energy antideuterons seems a plausible alternative. We apply our calculation to the AMS experiment, when mounted on the International Spatial Station. If a few low-energy antideuterons will be discovered by AMS, this should be seriously taken as a clue for the existence of relic, massive neutralinos in the dark halo of our Galaxy.Comment: 8 pages, 8 figures, Talk presented at the 4th International Symposium On Sources And Detection Of Dark Matter In The Universe (DM 2000), Marina del Rey, California, 23-25 Feb. 200

Photoionization yield and absorption coeffi- cient of xenon in the region 860-1022 deg angstrom

Photoionization yield and absorption coefficient of xenon gas measured by photoelectric method

Some Intensity Measurements in the Vacuum Ultraviolet

Intensity measurements in vacuum ultraviolet - photoelectric yields of untreated metals and semiconductors measured by calibrated thermocoupl

Semidirect product gauge group [SU(3)c×SU(2)L]⋊U(1)Y[SU(3)_{\rm c} \times SU(2)_{\rm L}]\rtimes U(1)_{\rm Y} and quantization of hypercharge

In the Standard Model the hypercharges of quarks and leptons are not determined by the gauge group $SU(3)_{\rm c} \times SU(2)_{\rm L} \times U(1)_{\rm Y}$ alone. We show that, if we choose the semidirect product group $[SU(3)_{\rm c} \times SU(2)_{\rm L}] \rtimes U(1)_{\rm Y}$ as its gauge group, the hyperchages are settled to be $n/6 \mod {\mathbb{Z}}\;(n = 0,1,3,4)$. In addition, the conditions for gauge-anomaly cancellation give strong constraints. As a result, the ratios of the hypercharges are uniquely determined and the gravitational anomaly is automatically canceled. The standard charge assignment to quarks and leptons can be properly reproduced. For exotic matter fields their hypercharges are also discussed.Comment: 17 pages, 2 tables; LaTeX; typos corrected, references added or replaced, argument in Secs. 2 and 3 revised, results unchanged; to be published in Phys. Rew.

Serum vitamin D in patients with mild cognitive impairment and Alzheimer's disease

Objectives: To determine the relevance of Mini-Mental State Examination (MMSE), serum 25-hydroxyvitamin D (25(OH)D3), and 1,25(OH)2D3 concentrations to mild cognitive impairment (MCI) and various stages of Alzheimer's disease (AD). Materials and Methods: The study included 230 participants (>74 years) allocated to three main groups: 1-healthy subjects (HS, n = 61), 2-patients with MCI (n = 61), and 3- patients with Alzheimer's disease (AD) subdivided into three stages: mild (n = 41), moderate (n = 35), and severe AD (n = 32). The cognitive status was evaluated using MMSE. Serum 25 (OH)D3 (ng/ml) and 1,25(OH)2D3 concentrations (pg/ml) were determined by competitive radioimmunoassay. Results: MMSE scores and 25(OH)D3 were decreased in MCI and all stages of the AD in both genders. MMSE variability was due to gender in HS (11%) and to 25(OH)D3 in MCI (15%) and AD (26%). ROC analysis revealed an outstanding property of MMSE in diagnosis of MCI (AUC, 0.906; CI 95%, 0.847–0.965; sensitivity 82%; specificity, 98%) and AD (AUC, 0.997; CI 95%, 0.992–1; sensitivity, 100%; specificity, 98%). 25(OH)D3 exhibited good property in MCI (AUC, 0.765; CI 95%, 0.681–0.849; sensitivity, 90%; specificity, 54%) and an excellent property in diagnosis of AD (AUC, 0.843; CI 95%, 0.782–0.904; sensitivity, 97%; specificity, 79%). Logistic analyses revealed that, in MCI, MMSE could predict (or classify correctly) with 97.6% accuracy (Wald, 15.22, β, −0.162; SE, 0.554; OR = 0.115:0.039–0.341; p =.0001), whereas 25(OH)D3 with 80% accuracy (Wald, 41,013; β, −0.213; SE, 0.033; OR = 0.808: 0.757–863; p =.0001). 25(OH)D3 was the only significant predictor for the severe AD and contributed to MMSE variability. Age and gender were significant predictors only in the moderate AD. In patients with MCI, 25(OH)D3 and 1,25(OH)2D3 were correlated men, but in case of the AD, they were correlated in women. Conclusions: MMSE and serum 25(OH)D3 concentrations could be useful biomarkers for prediction and diagnosis of MCI and various stages of the AD. The results support the utility of vitamin D supplementation in AD therapy regimen. © 2018 The Authors. Brain and Behavior published by Wiley Periodicals, Inc