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61.
Food and Environmental Virology - Retail foodservice establishments (FSE) frequently utilize washes with sanitizing agents during fresh produce preparation. This study evaluated the efficacy of... 相似文献
62.
Leaf-cutter ants with worn mandibles cut half as fast,spend twice the energy,and tend to carry instead of cut 总被引:1,自引:0,他引:1
Robert M. S. Schofield Kristen D. Emmett Jack C. Niedbala Michael H. Nesson 《Behavioral ecology and sociobiology》2011,65(5):969-982
The importance of mechanical wear in the behavioral ecology and energetics of small organisms is an open question. We investigated
wear in leaf-cutter ants, Atta cephalotes, because their cutting technique can be imitated and the leaves are the main energy source for the colony. We found that
a razor-sharp (50-nm radius) “V-blade” that cuts leaves between the first and second mandibular teeth was dulled (∼10-μm radius)
and often nearly worn away on foragers. We found that the force required to cut standard leaves, using mandibles removed from
foragers cutting in the wild, varied by a factor of 2.5 with tooth wear, defined as the difference between pupal and actual
tooth length. We also found that wear significantly reduced the cutting rate. From the distribution of wear among the cutting
foragers, we estimated that the wild colony would have spent 44% less of both energy and time making the observed cuts if
the cutters’ mandibles had all been pristine. Finally, wear correlated with behavioral differences—foragers with the most
worn 10% of mandibles almost exclusively carried rather than cut. This previously unreported form of task partitioning suggests
that eusociality may extend useful lifespans by making it possible to switch tasks as skills decline. We developed a model,
assuming that ants do work at a constant rate proportional to their mass, to predict the cutting rate from head width, tooth
wear, and force to cut leaves with a scalpel (R = 0.62), and we used this estimate to argue that the partitioning of cutting and carrying was sub-optimal but better than
random. Wear’s strong effect on performance may promote wear-avoiding behavior and wear-resistant mandible composition; it
may affect leaf selection and worker lifespan and it raises the possibility that wear is a similarly important constraint
for many other small organisms. 相似文献
63.
Abstract Energy- and water-saving have been promoted as ways of saving money while there has been controversy about the effects (if any) of such measures on resident health. In public housing in the US, energy saving has taken the form of Energy Savings Performance Contracts (ESPC) that pay for renovations out of future savings. In an attempt to test feasibility and pilot research methods we conducted a study of the relationship between gas and water use, exterior heat sensor locations, and basement ventilation with indices developed from resident-reported living conditions and health symptoms in a single housing development. The data sources that we had available to us were not ideal. In particular, we were unable to obtain water use data that coincided in time with our health survey data. Also, we did not have enough surveys in buildings with high water or gas use and had to pool those buildings with other buildings for analysis. Nevertheless, we found several associations between our measures of energy use and resident reports of health symptoms. The associations that we found were generally in the direction that energy and water savings were associated with fewer symptoms and fewer environmental problems. There is a need for studies that obtain better input data but that generally follow the approach we developed. 相似文献
64.
The institutional structure and public service delivery apparatus required to meet the future effects of climate change already exist in Norway. However, there are huge challenges in coordinating these institutions at different authority levels for climate change adaptation purposes. Based upon a broad case study, this article presents how local actors consider the multi-level coordination of different levels of government and policy sectors to function today, which are the mechanisms that are used and what are the coordination challenges that are identified. Based upon the challenges revealed, this article discusses how best can the government-level institutions be organised for better goal attainment. We argue here that the elected regional level in Norway – the counties – has a huge potential to act as a multi-level coordination actor. 相似文献
65.
An Erratum has been published for this article in Remediation 16(1) 2005, 155–157. Water‐level data collection is a fundamental component of groundwater investigations and remediation. While the locations and depths of monitored wells are important, the frequency of data collection may have a large impact on conclusions made about site hydrogeology. Data‐logging water‐level probes may be programmed to record water levels at frequent intervals, providing site decision makers with abundant, detailed information on the response of an aquifer to both anticipated and unforeseen stresses. In this study, a network of movable probes has provided several years of hourly water‐ level data. The understanding of the site's phytoremediation system has been enhanced by the continuous data, but subsequent insights into an unexpected situation regarding the site's infrastructure have been the most valuable result of the monitoring program. © 2005 Wiley Periodicals, Inc. 相似文献
66.
Environmental contamination with ionic chromium has been identified as a problem at numerous Superfund and RCRA Corrective Action sites. In many cases, contamination of groundwater to levels above existing standards or criteria may be a potential problem both for direct consumption of groundwater and for transport of mobile forms of chromium to areas such as basements where it can becontacted. In the environment, chromium occurs in two forms: trivalent and hexavalent. The trivalent form is generally immobile and nontoxic; hexavalent chromium is generally mobile and toxic. This article first presents the extent of the chromium problem, reviews the environmental chemistry literature on chromium, and reviews existing treatment technology for chromium immobilization in the nontoxic trivalent state. Finally, we present a case study where immobilization of chromium occurred through natural processes allowing a modified no-action scenario for site remediation. 相似文献
67.
Ton H. Snelder Doug J. Booker John M. Quinn Cathy Kilroy 《Journal of the American Water Resources Association》2014,50(1):111-127
Regression models of mean and mean annual maximum (MAM) cover were derived for two categories of periphyton cover (filaments and mats) using 22 years of monthly monitoring data from 78 river sites across New Zealand. Explanatory variables were derived from observations of water quality variables, hydrology, shade, bed sediment grain size, temperature, and solar radiation. The root mean square errors of these models were large (75‐95% of the mean of the estimated values). The at‐site frequency distributions of periphyton cover were approximated by the exponential distribution, which has the mean cover as its single parameter. Independent predictions of cover distributions at all sites were calculated using the mean predicted by the regression model and the theoretical exponential distribution. The probability that cover exceeds specified thresholds and estimates of MAM cover, based on the predicted distributions, had large uncertainties (~80‐100%) at the site scale. However, predictions aggregated by classes of an environmental classification accurately predicted the proportion of sites for which cover exceeded nominated criteria in the classes. The models are useful for assessing broad‐scale patterns in periphyton cover and for estimating changes in cover with changes in nutrients, hydrological regime, and light. 相似文献
68.
69.
Kristen M. Hart Autumn R. Sartain Zandy-Marie Hillis-Starr Brendalee Phillips Philippe A. Mayor Kimberly Roberson Roy A. Pemberton Jr. Jason B. Allen Ian Lundgren Susanna Musick 《Marine Biology》2013,160(10):2567-2580
Surveys of juvenile hawksbills around Buck Island Reef National Monument, US Virgin Islands from 1994 to 1999 revealed distributional patterns and resulted in a total of 75 individual hawksbill captures from all years; turtles ranged from 23.2 to 77.7 cm curved carapace length (CCL; mean 42.1 ± 12.3 cm SD). Juveniles concentrated where Zoanthid cover was highest. Length of time between recaptures, or presumed minimum site residency, ranged from 59 to 1,396 days (mean 620.8 ± 402.4 days SD). Growth rates for 23 juveniles ranged from 0.0 to 9.5 cm year?1 (mean 4.1 ± 2.4 cm year?1SD). Annual mean growth rates were non-monotonic, with the largest mean growth rate occurring in the 30–39 cm CCL size class. Gastric lavages indicated that Zoanthids were the primary food source for hawksbills. These results contribute to our understanding of juvenile hawksbill ecology and serve as a baseline for future studies or inventories of hawksbills in the Caribbean. 相似文献
70.
The Gaps between Theory and Practice in Selecting Nature Reserves 总被引:15,自引:0,他引:15