Mercury distribution and deposition in glacier snow over western China

Western China is home to the largest aggregate of glaciers outside the polar regions, yet little is known about how the glaciers in this area affect the transport and cycling of mercury (Hg) regionally and globally. From 2005 to 2010, extensive glacier snow sampling campaigns were carried out in 14 snowpits from 9 glaciers over western China, and the vertical distribution profiles of Hg were obtained. The Total Hg (THg) concentrations in the glacier snow ranged from <1 to 43.6 ng L(-1), and exhibited clear seasonal variations with lower values in summer than in winter. Spatially, higher THg concentrations were typically observed in glacier snows from the northern region where atmospheric particulate loading is comparably high. Glacier snowpit Hg was largely dependent on particulate matters and was associated with particulate Hg, which is less prone to postdepositional changes, thus providing a valuable record of atmospheric Hg deposition. Estimated atmospheric Hg depositional fluxes ranged from 0.74 to 7.89 μg m(-2) yr(-1), agreeing very well with the global natural values, but are one to two orders of magnitude lower than that of the neighboring East Asia. Elevated Hg concentrations were observed in refrozen ice layers in several snowpits subjected to intense melt, indicating that Hg can be potentially released to meltwater.     

Characteristics of Extracted Valerenic Acids From Valerian (Valeriana Officinalis) Root by Supercritical Fluid Extraction Using Carbon Dioxide

The extraction of valerenic acids from valerian root by supercritical fluid extraction using CO₂ under different operating conditions was compared to extraction by percolation using 70% ethanol. The yield of total valerenic acids under pressures of 10–20 MPa and temperatures of 40–50°C was about 85% of that achieved by percolation, while the addition of 5% ethanol or methanol as a modifier to the CO₂ resulted in the same yield as percolation. Moreover, maximal extraction was achieved in the faster time of 20 minutes and resulted in a more highly concentrated extract than obtained by percolation which would aid the manufacturing of liquid or dried products. Further studies on a larger scale would clarify the use of this technique commercially.     

A social-interactional model of the development of depressive symptoms in adolescence.

This study used longitudinal, multimethod data to examine specific patterns of behavioral interaction with parents and peers that were hypothesized to predict increasing levels of depressive symptoms in early adolescence. Adolescents' struggles in establishing autonomy and relatedness in interactions with mothers, and a withdrawn, angry, or dependent pattern of behavior with a best friend, were assessed with observational and peer-report methods in a community sample of 143 adolescents, who were also assessed for levels of depressive symptoms at age 13 and with whom the authors followed up 1 year later. Study hypotheses were confirmed, with dysfunctional interaction patterns with parents and peers combining additively to account for substantial change variance in depressive symptoms over time. Results are interpreted as highlighting specific behavioral patterns that may be promising to address via psychosocial interventions targeting adolescent depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting inept discipline: The role of parental depressive symptoms, anger, and attributions.

Relations among parents' psychological difficulties (i.e., depressive symptoms, overt anger), dysfunctional attributions for child misbehavior, and inept discipline were investigated in a representative community sample of 451 mothers and 449 fathers. Depressive symptoms and anger were hypothesized to relate to discipline via their link with parents' attributions. Path analyses revealed that depressive symptoms predicted parent-centered causal attributions (i.e., stable, global, and dispositional), which, in turn, related to laxness. Depressive symptoms also predicted child-centered responsibility attributions (i.e., controllable, intentional, and negative), which, in turn, related to overreactivity. Anger predicted overreactivity directly. The patterns of relations were similar for fathers and mothers. The importance of addressing parents' psychological difficulties and dysfunctional attributions in interventions for families with disruptive children is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

使VoIP用户体验超越QoS

目前，大多数传统网络服务供应商才刚开始推出VoIP服务。在早期阶段，众多供应商仅提供简单的VoIP通信功能，而VoIP的管理功能最多也只能算作初级水平。一旦出了问题，供应商缺乏解决问题的工具和技能。即便是能与ILEC展开竞争的新一代VoIP服务供应商也难以快速明确问题的原因并解决问题。     

Gender differences in negative affectivity among university faculty members.

Negative affectivity (NA) and Type A behavior were assessed in a sample of 96 male and female university teachers. In general, female Ss scored lower than did male Ss on NA. The difference between men and women on the NA component of hostility was quite profound. A small yet significant Gender–TABP (Type A behavior pattern) interaction effect was found in which high Type A women exhibited less NA (principally in the form of trait anxiety) than did high Type A men. Because NA has been related to both psychological and physical health complaints, some speculations are offered concerning physical and psychological health differences between men and women (at least within university faculties). The possibility is also raised of there being different psychological and physical consequences for being high on anger and/or Type A in women vs men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in surface area and concentrations of semivolatile organic contaminants in aging snow

During the winter of 1999/2000 five snowpacks at Turkey Lake Watershed east of Lake Superior were sampled immediately after falling and again after several days of aging for the analysis of specific snow surface area and the concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The snow surface could be determined with a relative coefficient of variation of 6% using frontal chromatography, measuring the retention of ethyl acetate, a substance with known adsorption coefficient on the ice surface. The snow surface area of fresh snow varied from 1000 to 1330 cm2/g and was higher for snow falling during colder days. The aged snow samples had consistently lower surface areas ranging from 520 to 780 cm2/g, corresponding to an average loss of half of the initial surface area during aging. The rate of loss of surface area was faster at higher temperatures. Dieldrin, alpha-HCH, and gamma-HCH were the most abundant OCPs in snowmelt water, but endosulfan, chlordane-related substances, heptachlor epoxide, pp'-DDT, pp'-DDE, and chlorinated benzenes were also consistently present. Three midwinter snowpacks that aged during relatively cold temperatures generally experienced a loss of PCBs and OCPs that was of the same order of magnitude as the observed loss of snow surface area. However, no relationship between the extent of loss and the strength of a contaminants' sorption to snow was apparent. Few significant changes in snowpack concentrations of OCPs and PCBs were observed in a snowpack that fell at relatively high temperatures and aged under colder conditions. Concentrations of OCPs and PCBs increased in a late-winter snowpack that aged while temperatures rapidly increased to above freezing. Concentrations of pp'-DDE and endosulfan-II that increased in snowpacks that saw simultaneous decreases in the levels of pp'-DDT and endosulfan-I hint at the occurrence of sunlight induced conversions in snow. While surface area decreases clearly contribute to the loss of semivolatile organic compounds from metamorphosing snowpacks, other confounding factors play a role in determining concentration changes, in particular in wet snow.