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41.
42.
J W Tyler J S Cullor M C Thurmond V L Douglas K M Parker 《American journal of veterinary research》1990,51(9):1400-1406
Logistic regression was used to develop models predicting preweaning survival in 334 neonatal swine. Measured risk factors included birth weight, litter size (live born), dam parity, serum IgG concentration, serum ELISA titers recognizing common gram-negative core antigens, and serum concentrations of the third component of complement. Larger birth weights were associated with increased probability of preweaning survival. The highest mortality was observed in litters with more than 12 pigs. Pigs with serum concentration of the third component of complement (C3) in the lowest stratum, less than 20% adult pooled C3 standard (APC3), had reduced mortality, compared with high (greater than 38% APC3) and middle (20 to 38% APC3) groups. Associations between all other variables, including total serum IgG concentration and preweaning survival were not significant. Few pigs had hypogammaglobulinemia, less than 3% of the study population had serum IgG concentrations less than 1 g/dl. Of all measured variables, only birth weight and dam parity were significant predictors of preweaning gain. Larger pigs and pigs born to third or greater parity dams had more preweaning gain than other pigs. 相似文献
43.
Relationships between landcover proportion and indices of landscape spatial pattern 总被引:10,自引:0,他引:10
Recent studies have related percolation theory and critical phenomena to the spatial pattern of landscapes. We generated simulated
landscapes of forest and non-forest landcover to investigate the relationship between the proportion of forest (Pi) and indices of patch spatial pattern. One set of landscapes was generated by randomly assigning each pixel independently
of other pixels, and a second set was generated by randomly assigning rectilinear clumps of pixels. Indices of spatial pattern
were calculated and plotted against Pi. The random-clump landscapes were also compared with real agricultural landscapes.
The results support the use of percolation models as neutral models in landscape ecology, and the performance of the indices
studied with these neutral models can be used to help interpret those indices calculated for real landscapes. 相似文献
44.
45.
Parker JS 《Journal of the American Veterinary Medical Association》2007,230(5):657; author reply 657-657; author reply 658
46.
The NeuroScope, a specific and sensitive indicator of cardiac vagal tone, was used to look for differences in autonomic tone between 25 dogs with naturally occurring diabetes mellitus and 23 healthy control dogs, to determine whether there was any correlation between the dogs' cardiac vagal tone, the duration of diabetes and the adequacy of glycaemic control. The cardiac index of parasympathetic activity (cipa) was determined for each dog over a period of 2600 heartbeats. The mean, median and modal cipa values were significantly lower in the diabetic dogs than in the healthy dogs. There was no significant relationship between the cipa values and the duration of disease or the adequacy of recent glycaemic control in the diabetic dogs, but there was a significant inverse relationship between the cipa values and the bodyweight of the diabetic dogs that was not evident in the normal dogs. The conclusions were based on a 500-heartbeat interval selected from the 2600 heartbeats recorded. 相似文献
47.
Genetic diversity within Australian wheat breeding programs based on molecular and pedigree data 总被引:8,自引:0,他引:8
124 wheat cultivars and breeding lines were screened with 19 microsatellite (SSR) loci generating 160 scorable bands which
were used to construct a genetic distance (GD) matrix. A distance matrix based on coefficient of parentage (COP) scores was
also generated for the cultivars for which good pedigree records were available. The SSR and COP data for 101 of the wheat
cultivars were compared with genetic distance scores obtained using1898 scorable restriction fragment length polymorphism
(RFLP) bands previously generated. Phylograms were generated based on the SSR, RFLP,combined SSR and RFLP and COP data. The
standardised Mantel's Z test showed that the distance matrices generated from all of the data sets were significantly correlated.
Bootstrap analysis showed that, although the SSR and RFLP data were correlated, a large number of SSR loci are required for
determining robust genetic relationships between large numbers of cultivars. In addition, accurate pedigree records are needed
to determine genetic relatedness using COP. The molecular data were also used to determine the level of genetic variability
within breeding programs and to assess the impact of the introduction of semidwarf and other germplasm. The results showed
that the level of genetic diversity in Australian wheat cultivars has increased over time and that in particular, the introduction
of semidwarf germplasm resulted in an increase in the overall diversity.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
48.
OBJECTIVE: To assess the use of folic acid supplementation in relation to small-area measures of social deprivation. DESIGN: Cohort study. SETTING: Antenatal clinic, Women's Outpatients Services, Cumberland Infirmary, Carlisle, UK. SUBJECTS: Four hundred and fifty women attending their 18-week antenatal clinic appointment. No selection criteria were applied. Townsend scores were allocated using postcodes to provide a small-area measure (enumeration district) of social deprivation. RESULTS: Eighty-nine per cent of women took folic acid prior to their 18-week antenatal clinic appointment; 48% of women took folic acid before 4 weeks of gestation. Younger women and more socially deprived women were less likely to use folic acid supplements before 4 weeks of gestation. Women with a family history of neural tube defects were no more likely to take folic acid than were women with no family history of neural tube defects. CONCLUSION: A high proportion of women reported taking folic acid supplements during pregnancy but less than half took them at the most important time in early pregnancy. Younger women and women who were more socio-economically deprived were much less likely to take folic acid during the critical periconceptional period. Future strategies should promote prenatal folic acid supplementation in women under the age of 24 and in women of low socio-economic status. Further attention should also be given to the use of folic acid supplements in women with a family history of neural tube defects. 相似文献
49.
H. Clayton I. P. McTaggart J. Parker L. Swan K. A. Smith 《Biology and Fertility of Soils》1997,25(3):252-260
The aim was to investigate the effects of different N fertilisers on nitrous oxide (N2O) flux from agricultural grassland, with a view to suggesting fertiliser practices least likely to cause substantial N2O emissions, and to assess the influence of soil and environmental factors on the emissions. Replicate plots on a clay loam
grassland were fertilised with ammonium sulphate (AS), urea (U), calcium nitrate (CN), ammonium nitrate (AN), or cattle slurry
supplemented with AN on three occasions in each of 2 years. Frequent measurements were made of N2O flux and soil and environmental variables. The loss of N2O-N as a percentage of N fertiliser applied was highest from the supplemented slurry (SS) treatment and U, and lowest from
AS. The temporal pattern of losses was different for the different fertilisers and between years. Losses from U were lower
than those from AN and CN in the spring, but higher in the summer. The high summer fluxes were associated with high water-filled
pore space (WFPS) values. Fluxes also rose steeply with temperature where WFPS or mineral N values were not limiting. Total
annual loss was higher in the 2nd year, probably because of the rainfall pattern: the percentage losses were 2.2, 1.4, 1.2,
1.1 and 0.4 from SS, U, AN, CN and AS, respectively. Application of U in the spring and AN twice in the summer in the 2nd
year gave an average emission factor of 0.8% – lower than from application of either individual fertiliser. We suggest that
similar varied fertilisation practices, modified according to soil and crop type and climatic conditions, might be employed
to minimise N2O emissions from agricultural land.
Received: 30 August 1996 相似文献
50.
Adams RL Mottram DS Parker JK Brown HM 《Journal of agricultural and food chemistry》2001,49(9):4333-4336
The irreversible binding of selected sulfur-containing flavor compounds to proteins was investigated in aqueous solutions containing ovalbumin and a mixture of disulfides (diethyl, dipropyl, dibutyl, diallyl, and 2-furfuryl methyl) using solid-phase micro-extraction (SPME). In systems which had not been heated, the recovery of disulfides from the headspace above the protein at the native pH (6.7) was similar to that from an aqueous blank. However, significant losses were observed when the pH of the solution was increased to 8.0. When the protein was denatured by heating, much greater losses were observed and some free thiols were produced. In similar heat-denatured systems at pH 2.0, no losses of disulfides were observed. Disulfides containing allyl or furfuryl groups were more reactive than saturated alkyl disulfides. Interchange reactions between protein sulfhydryl groups and the disulfides are believed to be responsible for the loss of the disulfides. 相似文献