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Jessica D Lightsey Sentiel A Rommel Alexander M Costidis Thomas D Pitchford 《Journal of zoo and wildlife medicine》2006,37(3):262-275
Between 1993 and 2003, 713 (24%) of 2,940 dead Florida manatees (Trichechus manatus latirostris) recovered from Florida waters and examined were killed by watercraft-induced trauma. It was determined that this mortality was the result of watercraft trauma because the external wound patterns and the internal lesions seen during gross necropsy are recognizable and diagnostic. This study documents the methods used in determining watercraft-related mortality during gross necropsy and explains why these findings are diagnostic. Watercraft can inflict sharp- and blunt-force trauma to manatees, and both types of trauma can lead to mortality. This mortality may be a direct result of the sharp and blunt forces or from the chronic effects resulting from either force. In cases in which death is caused by a chronic wound-related complication, the original incident is usually considered to be the cause of death. Once a cause of death is determined, it is recorded in an extensive database and is used by Federal and state managers in developing strategies for the conservation of the manatee. Common sequelae to watercraft-induced trauma include skin lesions, torn muscles, fractured and luxated bones, lacerated internal organs, hemothorax, pneumothorax, pyothorax, hydrothorax, abdominal hemorrhage and ascites, and pyoperitoneum. 相似文献
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Scott D. Foster Arūnas P. Verbyla Wayne S. Pitchford 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(2):300-314
The identification of quantitative trait loci (QTL) can be viewed as a subset selection problem. In a simulation study the
least absolute selection and shrinkage operator (LASSO) is shown to be a useful and powerful tool for QTL identification.
LASSO effects are embedded into a mixed model allowing simultaneous modeling of genetic and experimental effects. This provides
the flexibility to model the experiment in conjunction with the power of LASSO QTL identification. Estimation is performed
using an approximation to the restricted likelihood and modified Gaussian elimination. The extended mixed model is used to
analyze a cattle gene mapping dataset. 相似文献
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Recent analyses propose that the key regulatory processes in fisheries are stochastic, characterized by increased recruitment variance at low stock sizes (heteroscedasticity). Here, we investigate the consequences of this idea, with the aim of testing its practical relevance to fisheries management. We argue that stock‐recruitment time series are at least one order of magnitude too short to reliably fit heteroscedastic models; indeed, they are typically insufficient even to establish in which direction recruitment variance changes with stock size. Unreliable estimates of heteroscedasticity can have important management implications, depending on the sign of the coefficient of heteroscedasticity. Maximum sustainable yield (MSY) estimates from simple models, which include heteroscedasticity can be volatile, unrealistically high and sometimes non‐existent, as illustrated by an analysis of North Sea cod (Gadus morhua) data. In contrast, for North Sea herring (clupea harengus) data, heteroscedasticity has a negligible effect on MSY estimates. Statistical models are useful to elucidate broad‐scale regulatory processes, but will need to combined with the mechanistic understanding offered by models of population dynamics before being applied in a management setting. 相似文献
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Breed differences and genetic parameters for melting point, marbling score and fatty acid composition of lot-fed cattle 总被引：2，自引：0，他引：2
By A.E.O.Malau-Aduli M. A.Edriss B. D.Siebert C. D. K.Bottema W. S.Pitchford 《Journal of animal physiology and animal nutrition》2000,83(2):95-105
Fatty acid composition, marbling score and melting point data collected between 1994 and 1996 were analysed. The data were from the adipose tissue of 764 Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu crossbred cattle slaughtered after lot‐feeding at 500 days of age. The aim was to investigate sire‐breed differences and to estimate heritability and genetic and phenotypic correlations. Significant breed differences were found: Jersey crosses had the highest marbling score and Belgian Blue crosses had the lowest. Limousin crosses had the highest melting point and Jersey crosses the lowest. South Devon crosses had the highest proportion of stearate and Jersey crosses the lowest. Desaturation indices in C16 and C18 fatty acids were highest in Jersey crosses and lowest in Limousin and South Devon crosses. In contrast, there were no breed differences in the proportions of palmitate, oleate, total saturated, total mono‐unsaturated fatty acids and elongation index. Heritability estimates of individual fatty acids and their summations, melting point and marbling were low to moderately low (0.05–0.27). Strong genetic correlations of melting point and desaturation index in C16 fatty acids (‐0.93), melting point and stearate (0.62), marbling and stearate (‐0.71) and marbling and desaturation index in C18 fatty acids (0.62) were observed. Phenotypic correlation were generally low. The results imply that fatty acids in the adipose tissue of lot‐fed cattle have a moderately low heritability, hence genetic progress might be slow. 相似文献
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Davies J Honegger JL Tencalla FG Meregalli G Brain P Newman JR Pitchford HF 《Pest management science》2003,59(2):231-237
Herbicides entering the aquatic environment by spray drift, run-off and leaching to field drains may cause adverse effects on non-target aquatic vegetation. The potential for such effects has typically been evaluated from tests with floating, monocotyledonous Lemna sp. However, concern has been expressed as to whether this species could be used to indicate potential effects on other vegetation types, particularly rooted, submerged, emergent or dicotyledonous species. In 1997, the Centre for Aquatic Plant Management undertook development of new tests based on the additional species, Glyceria maxima (Hartm) Holmb, Lagarosiphon major (Ridl) Moss and Myriophyllum spicatum L. The resulting methodology was used to assess the effects of the sulfonylurea herbicide, sulfosulfuron on these species. Data presented here demonstrate that exposure to initial sulfosulfuron concentrations of 3.33 microg litre(-1) for up to 21 days was tolerated by these species and that adverse effects were observed only when plants were exposed to initial concentrations of 3.33 and 10 microg litre(-1) for 70 days. As the occurrence of such high initial concentrations for long periods is unlikely in the aquatic environment, sulfosulfuron is not expected to have adverse effects on the growth of these species. This study has also demonstrated that G maxima, L major and M spicatum grown in small outdoor tanks can be used successfully to assess the effects of crop-protection products on non-target aquatic flora. 相似文献
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A key to maximising response to selection in pastoral cattle kept by groups such as the Sub-Saharan Maasai is an accurate selection of young bulls. A breeding objective was developed based on weight, reproductive rate (days to calving), temperament, tick resistance and trypanotolerance. Accuracy of selection was defined as the correlation between the breeding objective and various selection indices. Accuracy was evaluated assuming availability of information on a range of traits (those in objective plus scrotal circumference) from individuals, parents, grand-parents, half-sibs, progeny and genetic markers. Various scenarios that represent what could occur at the village level were tested. Just selecting on weight alone had an accuracy of 0.538. Additional measurements on the individual (including repeated measures) had a large effect on accuracy. Records on relatives were less helpful than expected. Genetic markers for traits which are difficult to measure (days to calving and trypanotolerance) were helpful for improving accuracy. However, they are unlikely to be used in the near future because of cost and availability. An additional output from this study is simple selection indices that could be implemented immediately at the village level. 相似文献
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JH Waite GR Gladstone WS Lewis P Drossart TE Cravens AN Maurellis BH Mauk S Miller 《Science (New York, N.Y.)》1997,276(5309):104-108
Observations with the High Resolution Imager on the Rontgensatellit reveal x-ray emissions from Jupiter's equatorial latitudes. The observed emissions probably result from the precipitation of energetic (>300 kiloelectron volts per atomic mass unit) sulfur and oxygen ions out of Jupiter's inner radiation belt. Model calculations of the energy deposition by such heavy ion precipitation and of the resulting atmospheric heating rates indicate that this energy source can contribute to the high exospheric temperatures(>800 kelvin at 0.01 microbar) measured by the Galileo probe's Atmospheric Structure Instrument. Low-latitude energetic particle precipitation must therefore be considered, in addition to other proposed mechanisms such as gravity waves and soft electron precipitation, as an important source of heat for Jupiter's thermosphere. 相似文献