Long-term trends in the uptake of radiocesium in Rozites caperatus

Measurements of (134)Cs and (137)Cs in Rozites caperatus from 1991 to 2001 showed differences in the uptake pattern of Chernobyl and fallout derived radiocesium over time. The effective half-life of Chernobyl derived (137)Cs was determined to 12.4 years, whereas fallout derived (137)Cs had an effective half-life of 9.8 years. However, the trend for Chernobyl derived (137)Cs was clearly not linear. An effective average half-life of 3.1 years was determined for Chernobyl derived (137)Cs in the period from 1991 to 1994. The corresponding ecological half-life was 3.4 years. In the period from 1994 to 2001 it is possible that the effective half-life was longer than the physical, which indicates that more Chernobyl cesium becomes available than disappears through radioactive decay. The difference may be due to depth distribution of radiocesium, i.e. fallout derived cesium have penetrated deeper than Chernobyl. The changes in the half-lives of Chernobyl derived radiocesium over time together with the half-life of the older fallout derived radiocesium may be valuable in predictions of future radiocesium concentrations in mushrooms and thereby of food chain transfer to man.     

Runoff of particle bound pollutants from urban impervious surfaces studied by analysis of sediments from stormwater traps

Runoff sediments from 68 small stormwater traps around the harbor of urban Bergen, Norway, were sampled and the concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), heavy metals, and total organic carbon (TOC) were determined in addition to grain size. Our study provides empirical data from a large area in the interface between the urban and marine environment, studying the active transport of pollutants from land-based sources. The results of the analyses clearly demonstrate the importance of the urban environment representing a variety of contamination sources, and that stormwater runoff is an important dispersion mechanism of toxic pollutants. The concentrations of different pollutants in urban runoff sediments show that there are several active pollution sources supplying the sewage systems with PCBs, PAHs and heavy metals such as lead (Pb), zinc (Zn) and cadmium (Cd). The concentration of PCB7 in the urban runoff sediments ranged between < 0.0004 and 0.704 mg/kg. For PAH16, the concentration range was < 0.2-80 mg/kg, whereas the concentration ranges of Pb, Zn and Cd were 9-675, 51.3-4670 and 0.02-11.1 mg/kg respectively. Grain size distribution in 21 selected samples varied from a median particle diameter of 13 to 646 microm. However, several samples had very fine-grained particles even up to the 90 percentile of the samples, making them available for stormwater dispersion in suspended form. The sampling approach proposed in this paper will provide environmental authorities with a useful tool to examine ongoing urban contamination of harbors and similar recipients.     

Modeling of nonlinear responses for reciprocal transducers involving polarization switching

Nonlinearities and hysteresis effects in a reciprocal PZT transducer are examined by use of a dynamical mathematical model on the basis of phase-transition theory. In particular, we consider the perovskite piezoelectric ceramic in which the polarization process in the material can be modeled by Landau theory for the first-order phase transformation, in which each polarization state is associated with a minimum of the Landau free-energy function. Nonlinear constitutive laws are obtained by using thermodynamical equilibrium conditions, and hysteretic behavior of the material can be modeled intrinsically. The time-dependent Ginzburg-Landau theory is used in the parameter identification involving hysteresis effects. We use the Chebyshev collocation method in the numerical simulations. The elastic field is assumed to be coupled linearly with other fields, and the nonlinearity is in the E-D coupling. We present numerical results for the reciprocal-transducer system and identify the influence of nonlinearities on the system dynamics at high and low frequency as well as electrical impedance effects due to tuning by a series inductance. It is found that nonlinear effects are not important at high frequencies (1 MHz) subject to high-input voltages, but they become important under high-voltage and off-resonance conditions.     

Error estimation based on Superconvergent Patch Recovery using statically admissible stress fields

In this paper we investigate an approach for a posteriori error estimation based on recovery of an improved stress field. The qualitative properties of the recovered stress field necessary to obtain a conservative error estimator, i.e. an upper bound on the true error, are given. A specific procedure for recovery of an improved stress field is then developed. The procedure can be classified as Superconvergent Patch Recovery (SPR) enhanced with approximate satisfaction of the interior equilibrium and the natural boundary conditions. Herein the interior equilibrium is satisfied a priori within each nodal patch. Compared to the original SPR-method, which usually underestimates the true error, the present approach gives a more conservative estimate. The performance of the developed error estimator is illustrated by investigating two plane strain problems with known closed-form solutions. © 1998 John Wiley & Sons, Ltd.     

利用现代智能电池技术延长电池寿命

锂离子电池因其能量密度高而在便携应用中倍受青睐。但其电池管理系统并不尽如人意。结果不是电池比预期提前结束寿命就是造成剩余电量的浪费。针对对这种情况,智能电源管理系统应运而生,能够准确地对电池剩余电量进行估计,令电池的使用达到最佳化。     

A method for spatial interpolation of wind climatologies

The local wind climate is described by probability distributions for the wind direction and for the wind speed given a certain direction. As an alternative to the latter, the wind speed may be described by its statistical moments which are easily integrated over all directions. This allows representation of the wind climatology as a set of directionally independent statistics and the corresponding normalized directional distributions often called wind roses. The methodology is to spatially interpolate wind climatologies in an irregular mesh by two‐dimensioanl third‐order Bézier polynomials for the directionally independent statistics and linear interpolation for the wind roses. Local Bézier surfaces are set up in a patchwork of triangles and adjusted for approximate first‐order geometric continuity (GC¹) and minimal surface curvature. The wind rose interpolation is calculated relative to a typical local wind direction by means of Fourier transformation. A complementary surface extrapolation method is suggested which retains continuity on the grid boundary and asymptotically linear variation away from this. Copyright © 1999 John Wiley & Sons, Ltd.     

扩声系统语言清晰度的测量

用户都希望自己的扩声系统能满足多种使用需求、声音均匀覆盖全部区域、便于操作并且维护简单,其中最重要的评价标准有以下几点：（1）扩声系统有正确的高频、中频、低频比例,即“音色平衡”;（2）扩声系统播放声音的响度要合适;（3）扩声系统的声音来自正确的方向;（4）扩声系统播放清晰透彻的音乐和语言声音;（5）扩声系统要足够稳定可靠。     

Nanoscale InGaSb heterostructure membranes on Si substrates for high hole mobility transistors

As of yet, III-V p-type field-effect transistors (p-FETs) on Si have not been reported, due partly to materials and processing challenges, presenting an important bottleneck in the development of complementary III-V electronics. Here, we report the first high-mobility III-V p-FET on Si, enabled by the epitaxial layer transfer of InGaSb heterostructures with nanoscale thicknesses. Importantly, the use of ultrathin (thickness, ~2.5 nm) InAs cladding layers results in drastic performance enhancements arising from (i) surface passivation of the InGaSb channel, (ii) mobility enhancement due to the confinement of holes in InGaSb, and (iii) low-resistance, dopant-free contacts due to the type III band alignment of the heterojunction. The fabricated p-FETs display a peak effective mobility of ~820 cm(2)/(V s) for holes with a subthreshold swing of ~130 mV/decade. The results present an important advance in the field of III-V electronics.     

The alliance in couple therapy: Partner influence, early change, and alliance patterns in a naturalistic sample.

Objective: The purpose of this study was to explore the relationship between the alliance and outcome in couple therapy and examine whether the alliance predicted outcomes over and above early change. The authors also investigated partner influence and gender and sought to identify couple alliance patterns that predicted couple outcomes. Method: The authors examined the alliances and outcomes at posttreatment and follow-up of 250 couples seeking treatment for marital distress in a naturalistic setting. The Session Rating Scale was used to measure the alliance; the Outcome Rating Scale and Locke Wallace Marital Adjustment Scale were used to measure outcomes. Couples were White, Euro-Scandinavian, and heterosexual, with a mean age of 38.5 years and average number of years together of 11.8. On a subsample (n = 118) that included couples with 4 or more sessions, the authors investigated the relationship between the alliance and outcome controlling for early change, and patterns of alliance development were delineated. Results: In the full sample, first-session alliances were not predictive of outcomes, but last-session alliances were predictive for both individuals and their partners. In the subsample, third-session alliances predicted outcome significantly above early change (d = 0.25) that exceeded the reliable change index. Couple alliances that started over the mean and increased were associated with significantly more couples achieving reliable or clinically significant change. Gender influences were mixed. Conclusions: Given the current findings suggesting a potential alliance impact over and above symptom relief as well as the importance of ascending alliance scores, continuous assessment of the alliance appears warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in rumen bacterial and archaeal communities over the transition period in primiparous Holstein dairy cows

In the present study, we hypothesized that the rumen bacterial and archaeal communities would change significantly over the transition period of dairy cows, mainly as an adaptation to the classical use of low-grain prepartum and high-grain postpartum diets. Bacterial 16S rRNA gene amplicon sequencing of rumen samples from 10 primiparous Holstein dairy cows revealed no changes over the transition period in relative abundance of genera such as Ruminococcus, Butyrivibrio, Clostridium, Coprococcus, and Pseudobutyrivibrio. However, other dominant genus-level taxa, such as Prevotella, unclassified Ruminococcaceae, and unclassified Succinivibrionaceae, showed distinct changes in relative abundance from the prepartum to the postpartum period. Overall, we observed individual fluctuation patterns over the transition period for a range of bacterial taxa that, in some cases, were correlated with observed changes in the rumen short-chain fatty acids profile. Combined results from clone library and terminal-restriction fragment length polymorphism (T-RFLP) analyses, targeting the methyl-coenzyme M reductase α-subunit (mcrA) gene, revealed a methanogenic archaeal community dominated by the Methanobacteriales and Methanomassiliicoccales orders, particularly the genera Methanobrevibacter, Methanosphaera, and Methanomassiliicoccus. As observed for the bacterial community, the T-RFLP patterns showed significant shifts in methanogenic community composition over the transition period. Together, the composition of the rumen bacterial and archaeal communities exhibited changes in response to particularly the dietary changes of dairy cows over the transition period.