The NAIAD experiment for WIMP searches at Boulby mine and recent results     

B. Ahmed  G. J. Alner  H. Araujo  J. C. Barton  A. Bewick  M. J. Carson  D. Davidge  J. V. Dawson  T. Gamble  S. P. Hart  R. Hollingworth  A. S. Howard  W. G. Jones  M. K. Joshi  V. A. Kudryavtsev  T. B. Lawson  V. Lebedenko  M. J. Lehner  J. D. Lewin  P. K. Lightfoot  I. Liubarsky  R. Lüscher  J. E. McMillan  B. Morgan  G. Nicklin  S. M. Paling  R. M. Preece  J. J. Quenby  J. W. Roberts  M. Robinson  N. J. T. Smith  P. F. Smith  N. J. C. Spooner  T. J. Sumner  D. R. Tovey 《Astroparticle Physics》2003,19(6):691-702

The NAIAD experiment (NaI Advanced Detector) for weakly interacting massive particle (WIMP) dark matter searches at Boulby mine (UK) is described. The detector consists of an array of encapsulated and unencapsulated NaI(Tl) crystals with high light yield. Six crystals are collecting data at present. Data accumulated by four of them (10.6 kg × year exposure) have been used to set upper limits on the WIMP–nucleon spin-independent and WIMP–proton spin-dependent cross-sections. Pulse shape analysis has been applied to discriminate between nuclear recoils, as may be caused by WIMP interactions, and electron recoils due to gamma background. Various calibrations of crystals are presented.  相似文献   

The possible response of life zones in China under global climate change   总被引：5，自引：0，他引：5  

Xiongwen Chen  Xin-Shi Zhang  Bai-Lian Li 《Global and Planetary Change》2003,38(3-4):327-337

The response of natural vegetation to climate change is of global concern. In this research, an aggregated Holdridge Life Zone System was used to study the possible response of life zones in China under doubled atmospheric CO₂ concentration with the input climatic parameters at 0.5×0.5° resolution of longitude and latitude from NCAR regional climate model 2 (RegCM2) coupled with the CSIRO global climate model. The results indicate that the latitudinal distribution of life zones would become irregular because of the complicated climate change. In particular, new life zones, such as subtropical desert (SD), tropical desert (TDE) and tropical thorn woodland (TTW), would appear. Subtropical evergreen broadleaved forest (SEBF), tropical rainforest and monsoon forest (TRF), SD, TDE and TTW zones would appear in the northeastern China. Cool-temperate mixed coniferous and broadleaved forest (CMC) and warm-temperate deciduous broadleaved forest (WDBF) zones would appear at latitudes 25–35°N. The temperate desert (TD) in the western China would become Tibetan high-cold plateau (THP), SEBF, WDBF and temperate steppe (TS), and a large part of THP would be replaced by TRF, TDE, SEBF, TS and TTW. The relative area (distribution area/total terrestrial area) of CMC, TRF, TDE and TTW zone would increase about 3%, 21%, 3% and 6%, respectively. However, the relative area of SEBF, TS, TD and THP would decrease about 5%, 3%, 19% and 4%, respectively. In all, the relative area of forests (CCF, CMC, WDBF, SEBF, TRF) would increase about 15%, but the relative area of desert (TD, SD, TDE, and TTW) and THP would decrease about 9% and 4%, respectively. Therefore, responses of different life zones in China to climate change would be dramatic, and nationwide corridors should be considered for the conservation of migrating species under climate change.  相似文献   

A statistical evaluation of anomalous redshift claims     

W.M. Napier 《Astrophysics and Space Science》2003,285(2):419-427

Claims that ordinary spiral galaxies and some classes of QSO show periodicity in their redshift distributions are investigated using recent high-precision data and rigorous statistical procedures. The claims are broadly upheld. The periodicites are strong and easily seen by eye in the datasets. Observational, reduction or statistical artefacts do not seem capable of accounting for them. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

X-ray and ultraviolet observations of the dwarf nova VW Hyi in quiescence     

Dirk Pandel  France A. Córdova  Steve B. Howell 《Monthly notices of the Royal Astronomical Society》2003,346(4):1231-1241

We present an analysis of X-ray and ultraviolet (UV) data of the dwarf nova VW Hyi that were obtained with XMM–Newton during the quiescent state. The X-ray spectrum indicates the presence of an optically thin plasma in the boundary layer that cools as it settles on to the white dwarf. The plasma has a continuous temperature distribution that is well described by a power law or a cooling flow model with a maximum temperature of 6–8 keV. We estimate from the X-ray spectrum a boundary layer luminosity of  8 × 10³⁰ erg s^-1  , which is only 20 per cent of the disc luminosity. The rate of accretion on to the white dwarf is  5 × 10⁻¹² M_⊙ yr⁻¹  , about half of the rate in the disc. From the high-resolution X-ray spectra, we estimate that the X-ray emitting part of the boundary layer is rotating with a velocity of 540 km s⁻¹, which is close to the rotation velocity of the white dwarf but is significantly smaller than the Keplerian velocity. We detect a 60-s quasi-periodic oscillation of the X-ray flux, which is likely to be due to the rotation of the boundary layer. The X-ray and the UV flux show strong variability on a time-scale of ∼1500 s. We find that the variability in the two bands is correlated and that the X-ray fluctuations are delayed by ∼100 s. The correlation indicates that the variable UV flux is emitted near the transition region between the disc and the boundary layer and that accretion rate fluctuations in this region are propagated to the X-ray emitting part of the boundary layer within ∼100 s. An orbital modulation of the X-ray flux suggests that the inner accretion disc is tilted with respect to the orbital plane. The elemental abundances in the boundary layer are close to their solar values.  相似文献   

Protective effect of topically applied polypeptide from Chlamys farreri against ultraviolet radiation-induced chronic skin damage in guinea pig     

Chi Mingliang  Cao Pengli  Yu Guoying  Zhu Li  Wang Yuejun  Wang Chunbo 《中国海洋湖沼学报》2003,21(4):319-323

Polypeptide fromChlamys farreri (PCF), a topical polypeptide isolated fromChlamys farreri, was used in this experiment aimed to investigate the photoprotective effect of PCF against chronic skin damage induced by ultraviolet A (UVA) and ultraviolet B (UVB) radiation. The chronic ultraviolet-irradiated guinea pig model was established, and visible changes in the skin including wrinkling, sagging and erythema were observed. Malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in the dorsal skin were determined using biochemical methods. The results showed: (1) PCF (5 % and 20%) could greatly protect the dorsal skin of guinea pig against wrinkling, sagging and erythema induced by UV radiation in a concentration-dependent manner. (2) PCF could reduce MDA formation in the dorsal skin caused by UV irradiation, while increasing the activities of SOD and GSH-px. (3) The differences among the PCF groups and UV model group were significant (P<0.05,P<0.01). These results indicated that topical application, of PCF provided broad solar UV spectrum photoprotection; and that the antioxidant property of PCF might play a role in photoprotection. Project No. 39970638 supported by the NSFC, and the Science and Technology Bureau of Qingdao (No. 2001-28-50).  相似文献   

Simulation of stellar instabilities with vastly different time-scales using domain decomposition     

M. Grott  S. Chernigovski  W. Glatzel 《Monthly notices of the Royal Astronomical Society》2003,344(4):1119-1130

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蜕壳素对凡纳滨对虾生长及表观消化率的影响     

刘立鹤  郑石轩  徐焕新  郑献昌 《广东海洋大学学报》2003,23(4):30-36

研究了外源性蜕皮激素对凡纳滨对虾生长和表观消化率的影响 ,实验时在基础饲料中分别添加 0 .1%、0 .2 %、0 .4 %的两种市售蜕壳素产品 ,制成 6种外源性脱壳素配合饲料 ,不添加的基础饲料作为对照组 ,试验在 2 6 0L玻璃钢循环水养殖系统中 ,每个剂量组设 3个重复 ,8周生长试验结果表明 :市售蜕壳素产品能有效地促进对虾生长 ,试验结束时 ,试验组虾体增重分别较对照组增加 16 .8%、7.5 2 %、5 .9%、11.4 %、2 9.0 7%、16 .5 3% ,但是凡纳滨对虾对饲料粗蛋白的表观消化率没有明显地提高 ,凡纳滨对虾对脂肪的表观消化率较低。推算凡纳滨对虾饲料中最佳蜕皮酮添加量为 6 0mg/kg。  相似文献   

Numerical manifold method for dynamic nonlinear analysis of saturated porous media     

H. W. Zhang  L. Zhou 《国际地质力学数值与分析法杂志》2006,30(9):927-951

It is well known that the Babuska–Brezzi stability criterion or the Zienkiewicz–Taylor patch test precludes the use of the finite elements with the same low order of interpolation for displacement and pore pressure in the nearly incompressible and undrained cases, unless some stabilization techniques are introduced for dynamic analysis of saturated porous medium where coupling occurs between the displacement of solid skeleton and pore pressure. The numerical manifold method (NMM), where the interpolation of displacement and pressure can be determined independently in an element for the solution of u–p formulation, is derived based on triangular mesh for the requirement of high accurate calculations from practical applications in the dynamic analysis of saturated porous materials. The matrices of equilibrium equations for the second‐order displacement and the first‐order pressure manifold method are given in detail for program coding. By close comparison with widely used finite element method, the NMM presents good stability for the coupling problems, particularly in the nearly incompressible and undrained cases. Numerical examples are given to illustrate the validity and stability of the manifold element developed. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Middle-ear stiffness of the bottlenose dolphin tursiops truncatus     

Miller  B.S. Zosuls  A.L. Ketten  D.R. Mountain  D.C. 《Oceanic Engineering, IEEE Journal of》2006,31(1):87-94

Previous research on the cetacean auditory system has consisted mostly of behavioral studies on a limited number of species. Little quantitative physiologic data exists on cetacean hearing. The frequency range of hearing varies greatly across different mammalian species. Differences among species correlate with differences in the middle-ear transfer function. Middle-ear transfer functions depend on the mechanical stiffness of the middle ear and the cochlear input impedance. The purpose of this study was to measure the middle-ear stiffness for the bottlenose dolphin (Tursiops truncatus), a species specialized for underwater high-frequency hearing and echolocation. Middle-ear stiffness was measured with a force probe that applied a known displacement to the stapes and measured the restoring force. The average middle-ear stiffness in ten dolphin ears was 1.37 N//spl mu/m, which is considerably higher than that reported for most terrestrial mammals. The relationship between middle-ear stiffness and low-frequency hearing cutoff in Tursiops was shown to be comparable to that of terrestrial mammals.  相似文献   

Spinor: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory     

Hector Socas-Navarro  David Elmore  Anna Pietarila  Anthony Darnell  Bruce W. Lites  Steven Tomczyk  Steven Hegwer 《Solar physics》2006,235(1-2):55-73

The Spectro-Polarimeter for Infrared and Optical Regions (SPINOR) is a new spectro-polarimeter that will serve as a facility instrument for the Dunn Solar Telescope at the National Solar Observatory. This instrument is capable of achromatic polarimetry over a very broad range of wavelengths, from 430 to 1600 nm, allowing for the simultaneous observation of several visible and infrared spectral regions with full Stokes polarimetry. Another key feature of the design is its flexibility to observe virtually any combination of spectral lines, limited only by practical considerations (e.g., the number of detectors available, space on the optical bench, etc.). Visiting Astronomers, National Solar Observatory, operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation.  相似文献