草莓的花芽分化研究

草莓的花芽分化,是草莓花芽形成、结果、确定栽培形式、延长采果期以及获得产量的重要生理生态基础。近年来,国内外对此有较多的研究。本文综述了花芽分化模式,营养生长与休眠、光照、温度,及分化的生理机制等方面的研究结果。     

Evaluation of client compliance with short-term administration of antimicrobials to dogs

OBJECTIVE: To describe the degree of and variability in the level of client compliance and identify determinants of client compliance with short-term administration of antimicrobial medications to dogs. DESIGN: Prospective study. SAMPLE POPULATION: 90 owners of dogs prescribed antimicrobials. PROCEDURE: Eligible clients were invited to participate when antimicrobial medications were dispensed. Data were collected during a follow-up appointment by use of a client questionnaire, residual pill count, and return of an electronic medication monitoring device. Attending veterinarians also completed a questionnaire that asked them to predict client compliance. Methods of assessing compliance were compared with nonparametric tests. Generalized estimating equations were used to investigate potential determinants of compliance. RESULTS: Median compliance rates of 97% of prescribed container openings, 91% of days when the correct number of doses were given, and 64% of doses given on time as assessed by the electronic medication monitoring devices were significantly lower than the median compliance rates of 100% for client self-report of missing doses and pill count. Veterinarians were unable to predict client compliance. The dosage regimen significantly determined compliance. Clients giving antimicrobials once or twice daily were 9 times more likely to be 100% compliant, compared with 3 times daily dosing. CONCLUSIONS AND CLINICAL RELEVANCE: The combination of reported missed doses and pill counts was a significant predictor of compliance as measured by electronic monitoring. Electronic monitoring caps provided useful information only when they were used appropriately. Asking clients about missed doses and performing pill counts are the most practical assessments of compliance in practice.     

A unified nomenclature for quantification and description of water conducting properties of sapwood xylem based on Darcy's law

The literature dealing with the water conducting properties of sapwood xylem in trees is inconsistent in terminology, symbols and units. This has resulted from confusion in the use of either an analogy to Ohm's law or Darcy's law as the basis for nomenclature. Ohm's law describes movement of electricity through a conductor, whereas Darcy's law describes movement of a fluid (liquid or gas) through a porous medium. However, it is generally not realized that, in their full notation, these laws are mathematically equivalent. Despite this, plant physiologists have failed to agree on a convention for nomenclature. As a result, the study of water movement through sapwood xylem is confusing, especially for scientists entering the field. To improve clarity, we suggest the adoption of a single nomenclature that can be used by all plant physiologists when describing water movement in xylem. Darcy's law is an explicit hydraulic relationship and the basis for established theories that describe three-dimensional saturated and unsaturated flow in porous media. We suggest, therefore, that Darcy's law is the more appropriate theoretical framework on which to base nomenclature describing sapwood hydraulics. Our proposed nomenclature is summarized in a table that describes conventional terms, with their formulae, dimensions, units and symbols; the table also lists the many synonyms found in recent literature that describe the same concepts. Adoption of this proposal will require some changes in the use of terminology, but a common rigorous nomenclature is needed for efficient and clear communication among scientists.     

Carbohydrate transfer through root grafts to support shaded trees

We investigated whether root grafts between lodgepole pine (Pinus contorta var. latifolia Dougl. ex. Loud.) trees can transfer sufficient carbohydrate reserves from a source tree to a grafted sink tree to affect the vigor of trees growing in a light-limited environment. Eleven plots were established in early spring and two grafted tree pairs and two independent non-grafted trees were selected at each plot. One tree in a grafted pair and one non-grafted tree were shaded at each plot, whereas the remaining trees were non-shaded during the experimental period. Shaded trees had significantly lower carbohydrate reserves and smaller crowns than non-shaded trees following one growing season. Grafted shaded trees had significantly higher root total nonstructural carbohydrate concentrations than non-grafted shaded trees, indicating that root grafts partially offset the effects of shading. Also, large root grafts transferred proportionately more carbohydrates to the shaded trees than small root grafts. Carbohydrates transferred through root grafts could allow grafted trees to persist under conditions where non-grafted trees would be removed by competition.     

A critical review of the effectiveness of rodent pharmaceutical carcinogenesis testing in predicting for human risk

The pharmaceutical industry and regulatory agency toxicology testing paradigms in the United States currently appear successful, in part because of the continuously increasing life expectancy and the declining age-adjusted cancer rates in the United States. Although drugs likely have a minimal impact on the population statistics for cancer rates, pharmaceutical pathologists and toxicologists must focus on the individual risk for pharmaceutical carcinogenesis. As our understanding of carcinogenesis increases exponentially, and after hundreds if not thousands of rodent cancer tests, significant improvement in the precision of human pharmaceutical carcinogenesis hazard identification should now be possible and would enable a reduction in the substantial false-negative and false positive-rates reported herein. The appropriate use of acute, subchronic, chronic, and special toxicology tests to identify the major associated cancer risk factors, specifically, hormonal modulation, immunosuppression, genetic toxicity, and chronic toxicity, can be recognized through this review of pharmaceutical carcinogens. Significant opportunities exist for improving the effectiveness and efficiency of the current cancer risk assessment paradigm.     

Successful treatment of feline pyothorax associated with an Actinomyces species and Bacteroides melanogenicus

A cat was presented to a veterinary clinic with a severe pleural effusion from which an organism later identified as an Actinomyces spp., probably A. odontolyticus, was isolated along with Bacteroides melanogenicus. It was successfully treated with surgical drainage and a combination of amoxycillin and sulphadiazine/trimethoprim. The fluid was cytologically examined to obtain a provisional diagnosis and to allow treatment to be initiated while the organisms were cultured and identified. The cat is now clinically normal except for slight abdominal respiration, presumably resulting from adhesions following the severe infection.     

High-pressure and high-temperature experiments on core-mantle segregation in the accreting Earth

The abundances of siderophile elements in the Earth's silicate mantle are too high for the mantle to have been in equilibrium with iron in the core if equilibrium occurred at low pressures and temperatures. It has been proposed that this problem may be solved if equilibrium occurred at high pressures and temperatures. Experimental determination of the distribution of siderophile elements between liquid metal and liquid silicate at 100 kilobar and 2000 degrees C demonstrates that it is unlikely that siderophile element abundances were established by simple metal-silicate equilibrium, which indicates that the segregation of the core from the mantle was a complex process.