(137)Cs inter-plant concentration ratios provide a predictive tool for coral atolls with distinct benefits over transfer factors

Inter-plant concentration ratios (IPCR) [Bqg(-1)(137)Cs in coral atoll tree food crops/Bqg(-1)(137)Cs in leaves of native plant species whose roots share a common soil volume] can replace transfer factors (TF) to predict (137)Cs concentration in tree food crops in a contaminated area with an aged source term. The IPCR strategy has significant benefits relative to TF strategy for such purposes in the atoll ecosystem. IPCR strategy applied to specific assessments takes advantage of the fact that tree roots naturally integrate (137)Cs over large volumes of soil. Root absorption of (137)Cs replaces large-scale, expensive soil sampling schemes to reduce variability in (137)Cs concentration due to inhomogeneous radionuclide distribution. IPCR [drinking-coconut meat (DCM)/Scaevola (SCA) and Tournefortia (TOU) leaves (native trees growing on all atoll islands)] are log-normally distributed (LND) with geometric standard deviation (GSD)=1.85. TF for DCM from Enewetak, Eneu, Rongelap and Bikini Atolls are LND with GSDs of 3.5, 3.0, 2.7, and 2.1, respectively. TF GSD for Rongelap copra coconut meat is 2.5. IPCR of Pandanus fruit to SCA and TOU leaves are LND with GSD=1.7 while TF GSD is 2.1. Because IPCR variability is much lower than TF variability, relative sampling error of an IPCR field sample mean is up 6- to 10-fold lower than that of a TF sample mean if sample sizes are small (10-20). Other IPCR advantages are that plant leaf samples are collected and processed in far less time with much less effort and cost than soil samples.     

VOCs 组分监测数据在改进香港PATH 模型中的作用

 利用香港2 个监测站的VOCs 组分监测数据对香港PATH 模型进行了验证分析.结果明,PATH 模型在模拟VOCs 组分浓度上存在较大的误差.实际观测的VOCs 组分AOD、OLE、TOL 和XYL 浓度是模型模拟的2~3 倍;而模型模拟的PAR 和ETH 浓度是实际观测的 2~4倍.这些误差可能是由于当前使用的VOCs 排放清单低估了实际的VOCs 排放量,以及在估算来自不同排放源的排放量及组分分布上有较大的不确定性.使用高质量的VOCs 组分监测数据验证PATH 模型有助于指导改进VOCs 排放清单和理解复杂的光化学烟雾污染问题,从而改进和提高PATH 模型.     

Near-real-time determination of hydrogen peroxide generated from cigarette smoke

The ability to monitor hydrogen peroxide (H2O2) in aqueous smoke extracts will advance our understanding of the relationship between cigarette smoke-induced oxidative stress, inflammation, and disease and help elucidate the pathways by which the various smoke constituents exert their pathogenic effects. We have demonstrated, for the first time, the measurement of H2O2 production from cigarette smoke without prior separation of the sample. Cigarettes were tested on a commercial smoking machine, such that the whole smoke or gas vapor phase was bubbled through phosphate buffered saline solution at pH 7.4. Aliquots of these solutions were analyzed using an Amplex Red/horseradish peroxidase fluorimetric assay that required only a 2 minute incubation time, facilitating the rapid, facile collection of data. Catalase was used to demonstrate the selectivity and specificity of the assay for H2O2 in the complex smoke matrix. We measured approximately 7-8 microM H2O2 from two reference cigarettes (i.e., 1R4F and 2R4F). We also observed 9x more H2O2 from whole smoke bubbled samples compared to the gas vapor phase, indicating that the major constituent(s) responsible for H2O2 formation reside in the particulate phase of cigarette smoke. Aqueous solutions of hydroquinone and catechol, both of which are particulate phase constituents of cigarette smoke, generated no H2O2 even though they are free radical precursors involved in the production of reactive oxygen species in the smoke matrix.     

How do significant others influence our driving? A descriptive study of ego–alter dyads in a college population

Objectives: The purpose of this investigation was to describe the mutual influences between drivers and their significant others in a sample of college students, using a social network perspective.

Methods: A web-based survey was made of 65 dyads of drivers and their significant others, in order to examine areas of mutual influence concerning driving. Measures were taken of their frequency of risky driving, including how often they drive, talk on the cell phone, or text with each other while driving. They were also asked whether they have influenced or been influenced by each other to drive safer or in a more risky manner.

Results: The dyads were very similar in how frequently they drive as well as talk to each other on the phone while driving. However, they were unlikely to feel that their driving was influenced by each other, with only 17% of the drivers and 19% of the significant others saying that they have been overtly influenced by (or have influenced) each other's driving behavior often or most of the time. Yet, most (67.7% and 72.1%) said they have ever encouraged or been encouraged by each other to drive more safely, mainly by being told to reduce their speed. In both sets of drivers in these dyads, talking to and texting their significant other while driving was related to risky driving.

Conclusions: These findings suggest that a similarity exits in the driving patterns of young drivers and their significant others, especially concerning talking to each other on the phone while driving. The largest degree of overt social influence appears to center around avoidance of behaviors perceived to be associated with getting a traffic citation. Implications for safety campaign development and future research are presented.     

MODELING TIDAL HYDRODYNAMICS OF SAN DIEGO BAY,CALIFORNIA1

ABSTRACT: In 1983, current data were collected by the National Oceanic and Atmospheric Administration using mechanical current meters. During 1992 through 1996, acoustic Doppler current profilers as well as mechanical current meters and tide gauges were used. These measurements not only document tides and tidal currents in San Diego Bay, but also provide independent data sets for model calibration and verification. A high resolution (100-m grid), depth-averaged, numerical hydrodynamic model has been implemented for San Diego Bay to describe essential tidal hydrodynamic processes in the bay. The model is calibrated using the 1983 data set and verified using the more recent 1992–1996 data. Discrepancies between model predictions and field data in both model calibration and verification are on the order of the magnitude of uncertainties in the field data. The calibrated and verified numerical model has been used to quantify residence time and dilution and flushing of contaminant effluent into San Diego Bay. Furthermore, the numerical model has become an important research tool in ongoing hydrodynamic and water quality studies and in guiding future field data collection programs.     

Kinship,reproductive strategies and social dynamics of yellow-bellied marmots

Summary Social behavior of yellow-bellied marmots was observed for three years in colonies where kinship was known and for one year in a high elevation colony where harems were contiguous. Social dynamics of yellow-bellied marmots is dependent on kinship, group composition, and age-sex classes. This pattern is a consequence of the reproductive strategies of males and females. Females behave cohesively toward sisters or daughters, but not with sons and agonistically toward other females. Males generally behave amicably toward females and agonistically toward males, including their sons. Thus, reproductive strategies limit nepotism. This behavior is consistent with a population process in which sons typically disperse as yearlings. At least some of the variation in the expected patterns of social behaviors is attributable to individual differences. Because male and female reproductive strategies differ, a marmot population consists of two social subsystems. The female unit is the closely-related kin group which may also be a burrow group. The male unit is a harem which usually consists of two or more competing female kin groups.     

Seasonal decline in intracolony genetic relatedness in eastern tent caterpillars: implications for social evolution

Summary Genetic relatedness in social insect colonies may vary spatially or temporally as a result of changes in colony membership due to immigration or to variation in patterns of maternity and paternity. We estimated relatedness for eastern tent caterpillars (Malacosoma americanum) in laboratory colonies derived from egg masses using multilocus genotypic data derived from electrophoresis. This estimate is compared with estimates obtained from colony samples taken in the field at four intervals spanning the larval developmental season. We found that average intracolony relatedness is close to 0.5 initially but declines through the developmental season due to colony merging, showing that caterpillars do not discriminate between siblings and nonsiblings in order to preserve colony family structure. Using the intracolony values together with relatedness values for higher levels of population structure, we estimated the effective mean number of simple families represented in single colonies through the season. The overall effective number of families per tent increased from one at the time of eclosion to 1.3 by the end of the season. Average intracolony relatedness remained relatively high despite the occurrence of colony merging, apparently as a result of the low density of tents on most trees, combined with high relatedness within the original colonies. Thus, high intracolony relatedness is maintained in M. americanum populations through the effects of adult dispersal, mating, and oviposition patterns, rather than through behavioral discrimination mechanisms of the larvae. These findings underscore the importance of considering the causes of temporal variation in genetic relatedness as well as the consequences for the indirect component of inclusive fitness. Correspondence to: J.T. Costa