Detection of rotavirus and coronavirus shedding in two beef cow herds in Idaho

Fecal samples were taken at the time of pregnancy examinations and at parturition from two beef herds. They were also taken from sick calves at the onset of disease, and from 25% of the healthy calves at 15 days of age. All fecal samples were examined by electron microscopy for viruses.

Four cows in herd A were detected excreting coronavirus, one at the time of the pregnancy examinations and three at parturition. The first cow was removed from the herd and the others calved at the end of the season. There were no sick calves.

No cows in herd B were detected excreting virus at the time of pregnancy checks, but fourteen coronavirus and two rotavirus carrier cows were found at parturition. All but two calves sampled had large numbers of virus particles in their feces. Clinical illness was associated with dams shedding virus and with nightly low temperatures.

     

简述语言认知教学的理论和策略——第二语言习得(英文)

将部分第二语言习得理论和应用策略汇总,表述语言教育和教学法的系列原则和理论。这些原则和理论解释说明获得第二语言知识能力的惯例和基本规则,探讨学习者个别差异现象重要性,自主学习和指导学习获得第二语言能力的过程以及评估。理解这些理论可以帮助教师制定适当的教学计划,教学策略和合理的教学评估,引导教师和学生遵循低端认知要求,语境嵌入式课程到高端认知要求的连续语言教育和学习发展过程。     

Basidiospores of Phaeolus schweinitzii: a source of soil infestation

Persistent soil infestations with Phaeolus schweinitzii were successfully established in the forest environment using basidiospores, but there was no evidence that the fungus spread freeely through the soil while existing as a competitive saprophyte. Diseased stumps and roots of Sitka spruce remained a source of sporophore production for more than 17 years, but the principal flush of sporulation occurred within the first 7 years after felling.     

Nonenzymatic degradation of citrus pectin and pectate during prolonged heating: effects of pH, temperature, and degree of methyl esterification

The underlying mechanisms governing nonenzymatic pectin and pectate degradation during thermal treatment have not yet been fully elucidated. This study determined the extent of nonenzymatic degradation due to beta-elimination, acid hydrolysis, and demethylation during prolonged heating of citrus pectins and its influence on physicochemical properties. Solutions of citrus pectins, buffered from pH 4.0 to 8.5, were heated at 75, 85, 95, and 110 degrees C for 0-300 min. Evolution of methanol and formation of reducing groups and unsaturated uronides were monitored during heating. Molecular weight and viscosity changes were determined through size exclusion chromatography and capillary viscometry, respectively. Results showed that at pH 4.5, the activation energies of acid hydrolysis, beta-elimination, and demethylation are 95, 136, and 98 kJ/mol, respectively. This means that at this pH, acid hydrolysis occurs more rapidly than beta-elimination. Furthermore, the rate of acid hydrolysis is diminished by higher levels of methyl esterification. Also, citrus pectin (93% esterified) degrades primarily via beta-elimination even under acidic conditions. Acid hydrolysis and beta-elimination caused significant reduction in relative viscosity and molecular weight.     

Hood of the truck statistics for food animal practitioners.

This article offers some tips on working with statistics and develops four relatively simple procedures to deal with most kinds of data with which veterinarians work. The criterion for a procedure to be a "Hood of the Truck Statistics" (HOT Stats) technique is that it must be simple enough to be done with pencil, paper, and a calculator. The goal of HOT Stats is to have the tools available to run quick analyses in only a few minutes so that decisions can be made in a timely fashion. The discipline allows us to move away from the all-too-common guess work about effects and differences we perceive following a change in treatment or management. The techniques allow us to move toward making more defensible, credible, and more quantifiably "risk-aware" real-time recommendations to our clients.     

The amyloid precursor protein has a flexible transmembrane domain and binds cholesterol

C99 is the transmembrane carboxyl-terminal domain of the amyloid precursor protein that is cleaved by γ-secretase to release the amyloid-β polypeptides, which are associated with Alzheimer's disease. Nuclear magnetic resonance and electron paramagnetic resonance spectroscopy show that the extracellular amino terminus of C99 includes a surface-embedded "N-helix" followed by a short "N-loop" connecting to the transmembrane domain (TMD). The TMD is a flexibly curved α helix, making it well suited for processive cleavage by γ-secretase. Titration of C99 reveals a binding site for cholesterol, providing mechanistic insight into how cholesterol promotes amyloidogenesis. Membrane-buried GXXXG motifs (G, Gly; X, any amino acid), which have an established role in oligomerization, were also shown to play a key role in cholesterol binding. The structure and cholesterol binding properties of C99 may aid in the design of Alzheimer's therapeutics.     

Chlorophyll fluorescence of stem cambial tissue reflects dormancy development in Juglans nigra seedlings

Assessment of chlorophyll fluorescence (CF) of forest tree seedlings can provide important insight into physiological function, dormancy status, and stress resistance. This evaluative tool has been measured routinely using foliage on conifer seedlings to assess seedling physiological status during winter dormancy. Absence of foliage during dormancy has thus far precluded the potential application of CF to seedling quality assessment of temperate deciduous hardwood seedlings. Because stems contain chlorophyll, however, assessment of CF using stem tissue may serve as an effective alternative tissue type to facilitate CF measurements. We collected Juglans nigra L. (black walnut) seed from two provenances (Alabama and Indiana, USA) and subjected 1-year-old container seedlings from these provenances to a simulated hardening regime (i.e., progressively decreasing temperatures and photoperiods) in a growth chamber environment over an 18-week period; CF of stem tissue (evaluated as ΦPSII, efficiency of photosystem II) was sampled periodically at seven time intervals. Though both provenance and measurement period significantly affected ΦPSII, measurement period had a much more pronounced effect. Values for ΦPSII fluctuated (ranging from 0.45 to 0.72) during the simulated growth and hardening regimes, generally decreasing over time for both provenances. Our results suggest that physiological status of temperate deciduous seedlings may be effectively evaluated during dormancy by assessing CF of stem tissue.     

Quota allocation for stocks that span multiple management zones: analysis with a vector autoregressive spatiotemporal model

Allocating quotas among stakeholders requires an agreed-upon formula. If the stock unit spans multiple management jurisdictions, the formula may require updated biomass estimates of the stock's spatial distribution with respect to those jurisdictions. Data for calculating stock biomass often come from fishery-independent surveys. While stratified random sampling is a common design, strata boundaries may not always align with state or national jurisdictions, requiring post hoc stratification and imputation to calculate area-specific biomass. The vector autoregressive spatiotemporal (VAST) model was explored as a tool for calculating fish biomass within subareas of a defined stock unit for three different stocks jointly managed by the United States and Canada on Georges Bank in the Northwest Atlantic Ocean. VAST estimated proportions of stock biomass in each nation's waters were compared with an existing allocation algorithm that utilises a loess smooth through the average design-based swept area biomass from three fishery-independent surveys. The ability of VAST to impute biomass when no tows occur in a subarea of a survey stratum was demonstrated, as well as the relatively smoother biomass trend compared with design-based estimates, which may be desirable if the intent is to avoid large inter-annual swings in allocated quota.     

A retrospective study of the MRI findings in 18 dogs with stifle injuries

O bjectives : To make an objective assessment of the usefulness of magnetic resonance imaging in the diagnosis of meniscal damage and cranial cruciate ligament disease in the canine stifle by comparing magnetic resonance imaging findings with surgical findings.
M ethods : Magnetic resonance images of 18 stifles from 18 dogs which had undergone magnetic resonance imaging for the investigation of stifle disease were reviewed. For every stifle, the menisci and cranial cruciate ligaments were assessed according to predetermined criteria. The magnetic resonance imaging findings were compared with the reported surgical findings and the sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated using the surgical findings as the gold standard. Kappa analysis was used as an objective measure of agreement between surgical and magnetic resonance imaging findings. For 11 stifles, meniscal evaluation by three different observers was used to measure interobserver agreement using Kappa analysis.
R esults : Magnetic resonance imaging was demonstrated to be an accurate technique in the detection of meniscal injury (k=0·86), with excellent interobserver agreement (k=0·89 to 1·0). Disruption of cranial cruciate ligament continuity and an increase in ligament intensity were found to be useful criteria in the diagnosis of cranial cruciate ligament rupture.
C linical S ignificance : Magnetic resonance imaging offers a non-invasive alternative to exploratory surgery in the evaluation of cranial cruciate ligament and meniscal disease.