Birth sex ratios in sheep over six lambing seasons

Summary The birth sex ratio of a commercial flock of Suffolk × sheep, Ovis aries, were studied over six consecutive lambing seasons. In all, data from 1820 lambs were recorded and analysed. The overall birth sex ratio was 49.56% male lambs. Significantly more males (56.23%) were born to ewes with single lambs than to ewes with like-sex twins (47.73%). Significantly more female lambs were born to ewes with triplet births (41.79% male). A significant difference in the birth sex ratio was observed between the first and second half of the lambing season, among like-sex pairs of twin lambs. More males were born in the first half (51.43%) and significantly more females (43.59% male) in the second half of the lambing season. The results are discussed with reference to the theory of Trivers and Willard (1973).     

Experimental investigation of the effect of occupant characteristics on contemporary seat belt payout behavior in frontal impacts

Objective: The goal of this study was to investigate the influence of the occupant characteristics on seat belt force vs. payout behavior based on experiment data from different configurations in frontal impacts.

Methods: The data set reviewed consists of 58 frontal sled tests using several anthropomorphic test devices (ATDs) and postmortem human subjects (PMHS), restrained by different belt systems (standard belt, SB; force-limiting belt, FLB) at 2 impact severities (48 and 29 km/h). The seat belt behavior was characterized in terms of the shoulder belt force vs. belt payout behavior. A univariate linear regression was used to assess the factor significance of the occupant body mass or stature on the peak tension force and gross belt payout.

Results: With the SB, the seat belt behavior obtained by the ATDs exhibited similar force slopes regardless of the occupant size and impact severities, whereas those obtained by the PMHS were varied. Under the 48 km/h impact, the peak tension force and gross belt payout obtained by ATDs was highly correlated to the occupant stature (P =.03, P =.02) and body mass (P =.05, P =.04), though no statistical difference with the stature or body mass were noticed for the PMHS (peak force: P =.09, P =.42; gross payout: P =.40, P =.48). With the FLB under the 48 km/h impact, highly linear relationships were noticed between the occupant body mass and the peak tension force (R² = 0.9782) and between the gross payout and stature (R² = 0.9232) regardless of the occupant types.

Conclusions: The analysis indicated that the PMHS characteristics showed a significant influence on the belt response, whereas the belt response obtained with the ATDs was more reproducible. The potential cause included the occupant anthropometry, body mass distribution, and relative motion among body segments specific to the population variance. This study provided a primary data source to understand the biomechanical interaction of the occupant with the restraint system. Further research is necessary to consider these effects in the computational studies and optimized design of the restraint system in a more realistic manner.     

A Framework for a Delaware Inland Bays Environmental Classification

Since Delaware's coastal bays have been highly eutrophied for at least twenty years and Maryland's coastal bays are not nutrient stressed, dominance of the fish community in Delaware's coastal bays by Fundulus sp. may be an indicator of nutrient stress. Maryland's coastal bays are menhaden, spot, and anchovy dominated. The dominance of Fundulus sp. in a nutrient-stressed system relates to the hardy nature of these fishes, especially in low-oxygen conditions. Submerged aquatic vegetation as seagrasses (SAV) has been absent from the highly nutrient-stressed Delaware coastal bays for about twenty-five years. In contrast, SAV is still found in Maryland's coastal bays. The loss of SAV as a habitat for young fish may also be contributing to the apparent species shift in Delaware's coastal bays.Indian River Bay is less hospitable to macroalgae (seaweeds) than Rehoboth Bay. Dominance of Ulva in Indian River Bay reflects its tolerance to varying salinities, higher nutrient levels, and increased turbidities, and indicates a stressed system. The total volume of macroalgae, especially in Rehoboth Bay, tends to follow the seasonal cycle for phosphorus.Based on an assessment of the ecological condition of the Delaware and Maryland coastal bays conducted by EMAP in 1993 and other related studies, the author offers a conceptual framework for Delaware's inland bays environmental classification, considering the water quality parameters of turbidity, TSS, Chla, DIN, DIP, and O2 as they relate to presence of SAV, seaweed abundance and diversity, benthic invertebrate diversity, and fish sensitivity to low oxygen.     

The prevention of occupational injuries in two industrial plants using an incident reporting scheme

INTRODUCTION: The aim of this study was to examine whether the introduction of an incident reporting scheme with feedback in two industrial plants had an effect on the number of major incidents. METHOD: An intervention design with measurements before the implementation of the incident reporting scheme and two years later was used to examine the relationship between incident rates, safety climate, the willingness to report incidents and perceived management commitment to safety. RESULTS: The results showed that a successful implementation of an incident reporting scheme was followed by a decline in the incidence of major incidents at a Danish metal plant. A key factor in implementing the scheme was top management commitment, which was lacking at another plant, where the implementation of a similar scheme failed. CONCLUSION: Although the study shows some encouraging results concerning the use of incident reporting schemes to prevent occupational accidents, the possibility to draw causal conclusions is limited in the present study, and further studies are needed before the effectiveness of such schemes can be evaluated with certainty.     

Seasonal development of ozone-induced foliar injury on tall milkweed (Asclepias exaltata) in Great Smoky Mountains National Park

The goals of this study were to document the development of ozone-induced foliar injury, on a leaf-by-leaf basis, and to develop ozone exposure relationships for leaf cohorts and individual tall milkweeds (Asclepias exaltata L.) in Great Smoky Mountains National Park. Plants were classified as either ozone-sensitive or insensitive based on the amount of foliar injury. Sensitive plants developed injury earlier in the season and to a greater extent than insensitive plants. Older leaf cohorts were more likely to belong to high injury classes by the end of each of the two growing seasons. In addition, leaf loss was more likely for older cohorts (2000) and lower leaf positions (2001) than younger cohorts and upper leaves, respectively. Most leaves abscised without prior ozone-like stippling or chlorosis. Failure to take this into account can result in underestimation of the effects of ozone on these plants.     

Recent trends and projections of primary NO2 emissions in Europe

An assessment of recent trends in primary NO₂ emissions has been carried out for ten case study locations across the European Union. Estimates of the percentage of NO_x from road traffic emitted as primary NO₂ (f-NO₂) have been derived for 1995, 2000 and 2005 by combining the results of a literature survey of primary NO₂ emission factors for different vehicle types and technologies with an emission inventory. Estimates of f-NO₂ have also been derived from ambient monitoring data at roadside sites in each case study location using a model.The results of the analysis of trends show that f-NO₂ has increased in recent years and that the rate of increase has been greatest since 2000. f-NO₂ has increased from 8.6% in 2000 to 12.4% in 2004 as an average across the monitoring sites and from an average of 6.3% in 2000 to 10.6% in 2005 as an average of the emission inventory based calculations for the case study countries. f-NO₂ is predicted to increase further to an average of 19.6% in 2010 and 32.0% in 2020 as a result of the further penetration of exhaust after treatment technologies for diesel vehicles in the fleets. This increase is expected to be offset by the large reduction in NO_x emissions over this period, resulting in an increase in NO₂ emissions from road traffic to 2015, followed by a decline to close to 2004 levels by 2020. Estimates of future ambient NO₂ concentrations have also been calculated for the roadside monitoring sites included in the study. At 29 out of 45 of these sites the annual mean NO₂ limit value is predicted to be exceeded in 2010. At 22 of these sites, the annual mean concentration is expected to remain above the limit value until 2020 and beyond.     

SENSITIVITY OF GROUNDWATER FLOW MODELS TO VERTICAL VARIABILITY OF AQUIFER CONSTANTS1

ABSTRACT: The Ogallala aquifer in the Oklahoma Panhandle is in need of better management because of increased groundwater demand which has caused declines in static water levels at an alarming rate. A groundwater management computer model was developed for the Ogallala aquifer in the Texas Panhandle and treats the aquifer as a homogeneous system. In this study, the computer model has been modified in order to evaluate the effects of vertical layering on semi-static water level changes which occur during the dewatering of a single unconfined aquifer. The modified model was applied to a study area near Guymon, Oklahoma, using both the homogeneous and the multilayered cases. The aquifer is characterized by a saturated thickness of 400 feet. The accumulated drawdown values of the homogeneous and the multilayered cases demonstrate that an average difference of approximately 22% of the original saturated thickness occurs between the two cases before the base of the aquifer is encountered. Approximately 25% more time is required to dewater the layered aquifer. Thus, vertical variations of lithology in an aquifer such as the Ogallala should be considered when prediction is made relative to groundwater management.