Diode laser pumped, KERR phase-shifting and switching of a diode laser signal in a small area optical fibre

In this paper authors report the first demonstration of a diode laser powered Kerr effect device, consisting of a single birefringent fiber, able to phase-shift and switch an optical signal generated by a second laser diode. They have obtained fast, stable phase-shifting of 90° in a single fiber, at a coupled pump power of only 20 mW. Using this phase shift to induce polarization switching with resultant gating, 25% modulation of the diode laser signal has been observed, with a detection limited-rise time of 10ns.

Spectral measurement of diode lasers with a single-mode birefringent fibre

A new, and very simple spectrometer based on birefringent fiber is described. A resolution of 0.02 angstrom has been achieved, and the system has been used to measure diode laser chirp. A length of 10km of fiber would be sufficient to resolve single mode line widths.

Au@Si-n: Growth behavior, stability and electronic structure

The configurations, stability, and electronic structure of AuSin (n = 1-16) clusters have been investigated within the framework of the density functional theory at the B3PW91/LanL2DZ and PW91/DNP levels. The results show that the Au atom begins to occupy the interior site for cages as small as Si-11 and for Si-12 the Au atom completely falls into the interior site forming Au@Si-12 cage. A relatively large embedding energy and small HOMO-LUMO gap are also found for this Au@Si-12 structure indicating enhanced chemical activity and good electronic transfer properties. All these make Au@Si-12 attractive for cluster-assembled materials.

Magnetic silicon fullerene

A metal-encapsulating silicon fullerene, Eu@Si-20, has been predicted by density functional theory to be by far the most stable fullerene-like silicon structure. The Eu@Si-20 structure is a dodecahedron with D-2h symmetry in which the europium atom occupies the center site. The calculated results show that the europium atom has a large magnetic moment of nearly 7.0 Bohr magnetons. In addition, it was found that a stable "pearl necklace" nanowire, constructed by concatenating a series of Eu@Si-20 units, with the central europium atom, retains the high spin moment. The magnetic structure of the nanowire indicates potential applications in the fields of spintronics and high-density magnetic storage.

裂解气相色谱法讲座Ⅰ——裂解气相色谱法概述

裂解气相色谱法(Pyrolysis Gas Chromatography,简称PGC)是在热裂解和气相色谱两种技术的基础上发展起来的。自1954年W.H.T.Davison等人首先对高聚物的裂解产物进行气相色谱分离记出谱图而加以鉴别以来,经过S.B.Martin,R.S.Lehrle等人把高聚物的裂解技术直接同气相色谱仪连结在一起,由此建立了裂解气相色谱法。三十多年来,通过对裂解装置的不断改进和完善,以及采用毛细管分离、程序升温和微处理机系统,这一方法不仅广泛应用于高分子领域,并且也在微生物、生物、医学、药物、司法检验、地质、矿物燃料等方面得到了日益增长的应用。而方法本身,也从一种经验式的技术,发展为一门相对独立的分枝学科,成为同红外光谱法和核磁共振法相辅相成的分析和研究高分子及非挥发性有机化合物的不可缺少的有效的方法。

贵州红枫湖沉积物-水界面Fe、Mn地球化学研究

在地球环境的界面及其附近，发生着重要的物理、化学和生物反应，进行着频繁的物质交换和输送。研究和认识环境界面的地球化学过程对揭示环境演化、评价环境净化、认识成矿机理均具重要的科学意义。Fe、Mn是地表水环境中两个丰度最大的微量营养元素，也是典型的氧化还原敏感性元素，因其氧化物的吸附特性而对其它微量元素的地球化学行为有着显著的控制作用。因此，Fe、Mn地球化学的研究历来是水环境领域中令人瞩目的一个焦点。地表水环境中Fe、Mn的研究始于海底锰结核的发现及其成因问题的探讨，而Fe、Mn在湖泊研究中受到重视则始于湖泊富营养化问题的出现。二次大战使湖泊Fe、Mn的研究一度中断，直到七十年代因水资源短缺和水环境污染问题的出现才使这一研究重新受到重视，并于近十年得到迅速发展在采样技术、分析方法、Fe、Mn的形态、氧化还原作用、早期成岩作用以及地球化学循环机理的研究上取得了一系列重要的进展。其中以英国Davison的工作最引人注目。一般认为，Fe、Mn在湖泊中的行为受氧化还原边界层的控制。但是，由于研究方法的局限，缺乏将湖水和沉积物作为一个整体的系统研究。尤其是未能对沉积物-水界面及其附近Fe、Mn的行为开展细致的工作，因此在Fe、Mn循环机理的认识上尚存许多疑点。有鉴于此，本项研究着重探讨沉积物-水界面及其附近Fe、Mn的地球化学行为和特征。利用自制的湖泊沉积物和孔隙水取样装置，分别于春秋两季在红枫湖按垂直剖面采集湖水、界面水、孔隙水和沉积物样。采用滤膜技术作湖水、界面水和孔隙水Fe、Mn的形态分析，并作沉积物Fe、Fe~(3+)、Fe~(2+)、Mn、S和孔隙水P、HCO_(3~-)、SO_4~(2-)、NO_(3~-)等项目的分析，完成湖水、界面水的水化学全分析和沉积物的X-射线衍射分析。从而获得以下结果和认识：1.形态。湖水中Fe、Mn均呈微粒态；界面水中Fe呈微粒态，Mn则以微粒态为主，尚有部分离子态；孔隙水中Fe以离子态为主，存在部分胶体态，Mn则以离子态存在。2.特征剖面。春秋季湖水中距沉积物-水界面5m以上，Fe、Mn分布均一，5m以下，Fe、Mn均向界面递增10倍左右；界面水中，Fe、Mn继续向界面递增，但Fe在距界面10cm左右向界面略有递减，同时，在距界面20cm高度Fe的溶解态出现峰值分布，而Mn的溶解态则向界面递增；孔隙水中Fe、Mn均呈峰值分布，并均于12cm深度以下趋于稳定，其中Mn峰位于3cm深度，Fe峰则位下去8cm深度，Fe在10cm深度还存在一谷值分布；沉积物中Fe于7cm深度含量略呈下降趋势，Mn则在界面出现高值，并于0.5cm深度含理突降。3.界面通量。Fe在界面的沉降通量为10.9mg.cm~(-2)a~(-1)，扩散通量为-0.24mg.cm~(-2)a~(-1)，净重通量则为10.7mg.cm~(-2)a~(-1)，扩散量只有沉降通量的2%；Mn在界面的沉降通量为0.203mg.cm~(-2)a~(-1)，扩散通量为-0.062mg.cm~(-2)a~(-1)，净通量则为0.141mg.cm~(-2)a~(-1)，扩散通量占沉降通量的30%。Fe、Mn在界面的平流通量均可忽略不计。4.氧化还原作用。Fe、Mn在沉积物中按氧化电位的高低先后充当有机质分解的主要氧化剂，发生还原溶解，然后经扩散作用重新进入湖水中，并在氧化过程的作用下于界面附近形成微粒态Fe、Mn的富集。5.平衡矿物。沉积物孔隙水中Fe(II）的平衡矿物在8-12cm深度范围内为单硫铁矿（FeS)和黄铁矿（FeS_2)，12cm深度以下为菱铁矿（FeCO_3)；Mn（II）的平衡矿物则为菱锰矿（MnCO_3)。6.界面循环机理。在湖泊中Fe、Mn循环均受沉积物-水界面的控制围绕界面进行，循环过程由还原、扩散、氧化和沉降四个环节组成，其中Mn循环就在界面附近，而Fe循环则深入沉积物内部。Mn的界面循环相当激烈，Fe则较为缓和。Fe、Mn界面循环的结果使界面附近的湖水和沉积物中出现Fe、Mn的富集，其中Fe的富集程度 相对较小，Mn则非常显著。7.环境效应。Mn的界面循环可能导致~（210）Po的沉积后再迁移，而~（210）Pb的沉积后再迁移则可能与Fe的界面循环有关；Fe、Mn界面循环所形成的富集层对湖泊水库的水质构成严重的潜在威胁；根据Fe、Mn的还原优势作用带可以确定湖泊沉积物的氧化还原环境。

A toolkit approach to solar radiation modelling.

Considerable effort is required to implement solar radiation models in software. Many existing implementations have efficiency as their main priority rather than re-usability, and this can adversely affect their further development since the relationships between the software and physical quantities may be obscured. The Solar Toolkit is an attempt to overcome such barriers by exploiting the current abundance of computing resource, and the availability of user-oriented tools such as Microsoft Excel®. The Solar Toolkit takes the form of a set of functions written in Visual Basic for Applications® (VBA) made available under the Academic Free Licence. Transparency is the overriding priority throughout the implementation so that the Toolkit can provide a platform for further modelling initiatives.

The effect of 2 weeks vitamin C supplementation on immunoendocrine responses to 2.5 h cycling exercise in man

Davison G, Gleeson M, 2006. The effect of 2 weeks vitamin C supplementation on immunoendocrine responses to 2.5 h cycling exercise in man. European Journal of Applied Physiology 97(4): 454-461 RAE2008

Antioxidant supplementation and immunoendocrine responses to prolonged exercise

Davison, Glen, et al., 'Antioxidant supplementation and immunoendocrine responses to prolonged exercise', Medicine and Science in Sports and Exercise, (2007) 39(4) pp.645-652 RAE2008

Influence of acute vitamin C and/or carbohydrate ingestion on hormonal, cytokine, and immune responses to prolonged exercise

Davison, G. and Gleeson, M. (2005). Influence of Acute Vitamin C and/or Carbohydrate Ingestion on Hormonal, Cytokine, and Immune Responses to Prolonged Exercise. International Journal of Sport Nutrition and Exercise Metabolism. 15(5), pp.465-479 RAE2008

Bringing the gospel in Hogan and Pueblo, by Rev. J. Dolfin.

http://www.archive.org/details/bringinggospelin00dolfrich

Morphologically cryptic biological species within the liverwort Frullania asagrayana.

UNLABELLED: PREMISE OF THE STUDY: The Frullania tamarisci complex includes eight Holarctic liverwort species. One of these, F. asagrayana, is distributed broadly throughout eastern North America from Canada to the Gulf Coast. Preliminary genetic data suggested that the species includes two groups of populations. This study was designed to test whether the two groups are reproductively isolated biological species. • METHODS: Eighty-eight samples from across the range of F. asagrayana, plus 73 samples from one population, were genotyped for 13 microsatellite loci. Sequences for two plastid loci and nrITS were obtained from 13 accessions. Genetic data were analyzed using coalescent models and Bayesian inference. • KEY RESULTS: Frullania asagrayana is sequence-invariant at the two plastid loci and ITS2, but two clear groups were resolved by microsatellites. The two groups are largely reproductively isolated, but there is a low level of gene flow from the southern to the northern group. No gene flow was detected in the other direction. A local population was heterogeneous but displayed strong genetic structure. • CONCLUSIONS: The genetic structure of F. asagrayana in eastern North America reflects morphologically cryptic differentiation between reproductively isolated groups of populations, near-panmixis within groups, and clonal propagation at local scales. Reproductive isolation between groups that are invariant at the level of nucleotide sequences shows that caution must be exercised in making taxonomic and evolutionary inferences from reciprocal monophyly (or lack thereof) between putative species.

Effects of chronic mild traumatic brain injury on white matter integrity in iraq and afghanistan war veterans

Mild traumatic brain injury (TBI) is a common source of morbidity from the wars in Iraq and Afghanistan. With no overt lesions on structural MRI, diagnosis of chronic mild TBI in military veterans relies on obtaining an accurate history and assessment of behavioral symptoms that are also associated with frequent comorbid disorders, particularly posttraumatic stress disorder (PTSD) and depression. Military veterans from Iraq and Afghanistan with mild TBI (n = 30) with comorbid PTSD and depression and non-TBI participants from primary (n = 42) and confirmatory (n = 28) control groups were assessed with high angular resolution diffusion imaging (HARDI). White matter-specific registration followed by whole-brain voxelwise analysis of crossing fibers provided separate partial volume fractions reflecting the integrity of primary fibers and secondary (crossing) fibers. Loss of white matter integrity in primary fibers (P < 0.05; corrected) was associated with chronic mild TBI in a widely distributed pattern of major fiber bundles and smaller peripheral tracts including the corpus callosum (genu, body, and splenium), forceps minor, forceps major, superior and posterior corona radiata, internal capsule, superior longitudinal fasciculus, and others. Distributed loss of white matter integrity correlated with duration of loss of consciousness and most notably with "feeling dazed or confused," but not diagnosis of PTSD or depressive symptoms. This widespread spatial extent of white matter damage has typically been reported in moderate to severe TBI. The diffuse loss of white matter integrity appears consistent with systemic mechanisms of damage shared by blast- and impact-related mild TBI that involves a cascade of inflammatory and neurochemical events. © 2012 Wiley Periodicals, Inc.

Some models for discretized series of events

A discretized series of events is a binary time series that indicates whether or not events of a point process in the line occur in successive intervals. Such data are common in environmental applications. We describe a class of models for them, based on an unobserved continuous-time discrete-state Markov process, which determines the rate of a doubly stochastic Poisson process, from which the binary time series is constructed by discretization. We discuss likelihood inference for these processes and their second-order properties and extend them to multiple series. An application involves modeling the times of exposures to air pollution at a number of receptors in Western Europe.