An interpersonal perspective of perceived stress: Examining the prosocial coping response patterns of stressed managers

We adopt an interpersonal perspective and examine the adaptive effects of managers' perceived stress on their behavior towards subordinates. Drawing from the transactional model of stress (Lazarus & Folkman, 1984), we advance a model that highlights the propensity for stressed managers to engage in prosocial coping behaviors towards their employees, which in turn are related to lower levels of turnover and higher levels of job performance. We tested our predictions in a sample of 281 employees and their 53 managers working in a clothing retailer in Turkey. Consistent with predictions, we found positive effects of managers' perceived stress on their prosocial coping behaviors and employee outcomes. Managers' perceived stress was positively related to sharing credit with employees for managers who held positive implicit prototypes about employees. Results also indicated that managers' perceived stress was positively related to sharing knowledge with their subordinates regardless of implicit follower prototypes. Both sharing credit and sharing knowledge, in turn, were related to turnover intentions and actual turnover, and sharing credit was related to job performance. This study extends past work by adopting an interpersonal perspective of stress and demonstrating that managerial stress can have positive effects on employee outcomes via prosocial coping behaviors.     

Association of benzo(a)pyrene with dissolved organic matter: Prediction of Kdom from structural and chemical properties of the organic matter

The affinity of dissolved organic matter (DOM) for binding a polycyclic aromatic hydrocarbon, benzo(a)pyrene (BaP), was measured for 11 surface and ground waters and a commercial humic acid. The hydrophobic-acid (HbA) and hydrophobic-neutral (HbN) compositions of the DOM, solution absorptivity at 270nm (ABS₂₇₀), and DOM molar volumes were determined. Waters enriched in HbA material had a larger molar volume and higher aromatic content (as indicated by the ABS₂₇₀). There was a good correlation between the size and HbA content of the DOM from the different sources and the K_dom for binding BaP. An excellent predictive relationship (r² = 0.9) was demonstrated between the ABS₂₇₀ of a water and the K_dom for binding BaP. Based on these results, it is suggested that binding of BaP to DOM depends not only on the hydrophobicity of DOM, but also on the existence of an open structure within the DOM to provide access of the aqueous solute to hydrophobic domains within the DOM.     

Flooding patterns of the Okavango Wetland in Botswana between 1972 and 2000

The inundated area of the Okavango Delta changes annually and interannually. The variability relates to regional precipitation over the catchment area in the Angolan highlands, and to local rainfall. The patterns of the wetland were captured using more than 3000 satellite images for the period 1972 to 2000, near daily NOAA AVHRR data for 1985-2000, and less frequent images of the Landsat sensors from 1972 onwards. One AVHRR image for every 10-day period was classified into land and water using an unsupervised classification method. Evaluation against Landsat TM and ERS2-ATSR data indicate an agreement of 89% for the size of estimated inundation area. Results show that the wetland area has varied between approximately 2450 km2 and 11400 km2 during the last 30 years.     

Uptake and release of phosphorus by phytoplankton in the Chesapeake Bay estuary,USA

The phytoplankton uptake and release rates for inorganic phosphate, dissolved organic phosphate and polyphosphate were estimated during 5 cruises on the Chesapeake Bay over a 9-month period. Phosphorus in all pools turned over in several minutes to 100 h, and each soluble pool appeared to contain fractions which were metabolically useful to the phytoplankton. Maximal uptake rates (V _m ) for orthophosphate ranged from 0.02 to 2.95 μg-at P (1.h)^-1 with half saturation constants (K _s ) between 0.09 and 1.72 μg-at P l^-1. At low soluble reactive phosphorus concentrations, the uptake rate of trace ³²P orthophosphate was initially rapid, but declined after 15 to 60 min incubation. The data suggest that the initial uptake phase was dominated by exchange of ³²PO₄ ^≡ for ³¹PO₄ ^≡ in the membrane transport systems whereas the subsequent phase represented the net incorporation of orthophosphate into phytoplankton cells.     

Histological investigation of the reproductive cycles of the limpets <Emphasis Type="Italic">Patella </Emphasis><Emphasis Type="Italic">vulgata</Emphasis> and <Emphasis Type="Italic">Patella ulyssiponensis</Emphasis>

This study devised a staging system for, and monitored, the gonad development of the limpet species Patella vulgata and Patella ulyssiponensis on the South West coast of Ireland using histological techniques. Maturation began in the males of both species in January and in the females it began in March. There was no statistical difference in gonad development between sexes and between species. Spawning in the male P. vulgata occurred from September to December 2003 and in September and October 2004. In female P. vulgata spawning occurred from October to December 2003, no spawning of females was observed in 2004. In male P. ulyssiponensis spawning occurred in November and December 2003 and from September 2004 to December 2004. Spawning was observed from November 2003 to January 2004 and in September 2004 in female P. ulyssiponensis. Sex ratios also varied between the species and between months sampled. Nevertheless more males were observed in both species.     

Geographic variation in polyphenolic levels of Northeastern Pacific kelps and rockweeds

Brown algal polyphenolic compounds are secondary metabolites whose functions may include protecting plants from pathogens or damage by UV radiation, and deterring feeding by herbivores. We present here the first analysis of spatial variation (at scales from tens of meters to hundreds of kilometers) in concentration of these compounds in two orders of brown algae from the northeastern Pacific Ocean. In kelps (order Laminariales), variation among sites was significant in only 25% of species examined and was consistent within families (high in the Alariaceae and low in the Laminariaceae and Lessoniaceae). In rockweeds (order Fucales, family Fucaceae), site variation was high in three of four species examined. Both the proportion of high polyphenolic kelp species and the magnitude of spatial variation within species from both kelps and rockweeds were much higher than would have been predicted from previous studies in other regions. In one kelp (Laminaria groenlandica), significant differences between sites occurred at scales of only tens of meters. No latitudinal clines were observed. Differences in phenolic concentrations of kelps spanned nearly an order of magnitude in one species, Hedophyllum sessile. Phenolic levels were significantly higher in members of the Fucales than the Laminariales, but showed no significant differences between intertidal and subtidal species. Received: 22 July 1996 / Accepted: 26 October 1998     

Estrogenicity of pyrethroid insecticide metabolites

There is concern that insecticides are able to mimic the action of 17beta-estradiol by interaction with the human estrogen receptor. Pyrethroids are commonly used insecticides and several have been assessed for potential endocrine disrupting activity by various methods. It has been noted that some metabolites of pyrethroids, in particular, permethrin and cypermethrin, have chemical structures that are more likely to interact with the cellular estrogen receptor than the parent pyrethroid. For this study permethrin and cypermethrin metabolites 3-(4-hydroxy-3-phenoxy)benzyl alcohol, 3-(4-hydroxy-3-phenoxy)benzoic acid, and N-3-(phenoxybenzoyl)glycine were synthesised, and together with the commercially available 3-phenoxybenzyl alcohol, 3-phenoxybenzaldehyde, and 3-phenoxybenzoic acid, were studied in a recombinant yeast assay expressing human estrogen receptors (YES). Three metabolites, 3-phenoxybenzyl alcohol, 3-(4-hydroxy-3-phenoxy)benzyl alcohol, and 3-phenoxybenzaldehyde, showed estrogenic activity of approximately 10(5) less than that of 17beta-estradiol. No activity was observed in the yeast assay for 3-phenoxybenzoic acid, 3-(4-hydroxy-3-phenoxy)benzoic acid, and N-3-(phenoxybenzoyl)glycine. The results from this study show that pyrethroid metabolites are capable of interacting with the human estrogen receptor, and so might present a risk to human health and environmental well being. The impact would be expected to be small, but still add to the overall environmental xenoestrogen load.     

Local extinction of grassland plants: the landscape matrix is more important than patch attributes

Past studies of local extinctions in fragmented habitats most often tested the influence of fragment size and isolation while ignoring how differences in the surrounding landscape matrix may govern extinction. We assessed how both the spatial attributes of remnant patches (area and isolation) and landscape factors (extent of urbanization and maximum inter-fire interval) influence the persistence of native plant species in grasslands in western Victoria, Australia. Persistence was determined in 2001 by resurveying 30 remnants first surveyed in the 1980s, and correlates of extinction were assessed using Bayesian logistic regression models. On average, 26% of populations of native species became locally extinct over two decades. Area and isolation had little effect on the probability of local extinction, but urbanization and longer maximum inter-fire intervals increased extinction risk. These findings suggest that the native grasslands studied are relatively insensitive to area- and isolation-based fragmentation effects and that short-term persistence of plant populations requires the maintenance of habitat quality. The latter is strongly influenced by the landscape matrix surrounding remnant patches through changes in fire regimes and increased exogenous disturbance.     

A respirometric method to measure mineralization of polymeric materials in a matured compost environment

A respirometric method was developed to measure the mineralization of polymeric materials in a matured compost environment. For the purpose of evaluating the method, results obtained for the mineralization of glucose and cellulose are presented. The matured compost, in addition to supplied nutrients, micronutrients, and an inoculum, serves as the matrix which supports the microbial activity. Recovery of the substrate carbon in the form of carbon dioxide from the glucose and cellulose added to test vessels was 68 and 70%, respectively. A statistical evaluation of the results obtained on substrate mineralization was carried out and showed acceptable reproducibility between replicate test vessels and test runs. The testing protocol developed has the following important characteristics: (1) the test reactors are maintained at 53 °C at a high solids loading (60% moisture), which has certain characteristics that are similar to a thermophilic compost environment; (2) the test matrix providing microbial activity is derived from readily available organic materials to facilitate reproducibility of the method in different laboratories; (3) the equipment required to perform this test is relatively inexpensive; and (4) the information obtained on polymer mineralization is vital to the study and development of biodegradable polymeric materials.Guest Editor: Dr. Graham Swift, Rohm & Haas.     

Wintertime Vertical Variations in Particulate Matter (PM) and Precursor Concentrations in the San Joaquin Valley during the California Regional Coarse PM/Fine PM Air Quality Study

Abstract

Air quality monitoring was conducted at a rural site with a tower in the middle of California’s San Joaquin Valley (SJV) and at elevated sites in the foothills and mountains surrounding the SJV for the California Regional PM₁₀/M_2.5 Air Quality Study. Measurements at the surface and on a tower at 90 m were collected in Angiola, CA, from ecember 2000 through February 2001 and included hourly black carbon (BC), particle counts from optical particle counters, nitric oxide, ozone, temperature, relative humidity, wind speed, and direction. Boundary site measurements were made primarily using 24-hr integrated particulate matter (PM) samples. These measurements were used to understand the vertical variations of PM and PM precursors, the effect of stratification in the winter on concentrations and chemistry aloft and at the surface, and the impact of aloft-versus-surface transport on PM concentrations. Vertical variations of concentrations differed among individual species. The stratification may be important to atmospheric chemistry processes, particularly nighttime nitrate formation aloft, because NO₂ appeared to be oxidized by ozone in the stratified aloft layer. Additionally, increases in accumulation-mode particle concentrations in the aloft layer during a fine PM (PM_2.5) episode corresponded with increases in aloft nitrate, demonstrating the likelihood of an aloft nighttime nitrate formation mechanism. Evidence of local transport at the surface and regional transport aloft was found; transport processes also varied among the species. The distribution of BC appeared to be regional, and BC was often uniformly mixed vertically. Overall, the combination of time-resolved tower and surface measurements provided important insight into PM stratification, formation, and transport.