苹果果实日灼预测预报计算机模型

为了及时准确地预测预报苹果果实日灼发生的时间,提高预防措施的效果,特研制了本计算机模型.通过对树上活体果实表面温度进行生长季全程连续监测,同步对比相应的气象资料,研究了主要气象因子(包括气温、日照、风速和相对湿度)与果实表面温度的相关性,确定了上述气象要素与果实表面温度变化的多元回归方程.此外,通过比较研究不同品种、果实发育期以及树势对果实日灼敏感性的差异,确定了不同品种果实日灼阈值温度以及这些因子在影响果实日灼中的效应参数.将模型预测值与田间果实温度实测值进行对比,验证该模型预报结果符合率达85.22%.近两年该模型已开始在美国华盛顿州果园试用.通过在本模型的用户界面下拉菜单中选择品种、月份和树势,并在相应位置输入当日11∶00～14∶00平均日照、气温、风速和相对湿度数值,即可得到当日是否发生果实日灼的预测预报结果.     

A double-blinded placebo-controlled evaluation of adipose-derived mesenchymal stem cells in treatment of canine atopic dermatitis

Mesenchymal stem cells (MSCs) have emerged as a new therapy for various immune-mediated inflammatory diseases. In this study we perform the first double-blinded, placebo-controlled evaluation of the efficacy of adipose-derived allogenic canine MSCs for the treatment of canine atopic dermatitis (cAD). Enrolled canine patients were randomly divided into placebo (PBS saline), low-dose (5?×?10⁵ cells/kg), and high-dose (5?×?10⁶ cells/kg) treatment groups. Each patient received three subcutaneous MSCs treatments or PBS saline at four-week intervals with injections at five sites. Patients were monitored by physical exams, pruritus visual analog scales (PVAS) signed by the primary caretaker, canine atopic dermatitis extent and severity index-4 (CADESI-4) scores by two veterinarians, and complete blood count and serum chemistry analysis along with laboratory analysis for potential biomarkers. Patients were kept off any immune-modulating drugs during the study period, and oral antibiotics and topicals were used for managing pruritus and secondary infections. The PVAS scores and the serum miR-483 levels were significantly lower in the high dose group compared to the placebo group at day90 post first-treatment. The CADESI-4 scores of the high dose group also showed downward trends. No severe adverse effects were observed in any patient in this study. The high dose MSC treatment is efficacious in alleviating the clinical signs of cAD until 30 days after the last subcutaneous administration of MSCs, and miRNA-483 may be a reliable prognostic biomarker for cAD. The MSCs efficacy and potential biomarkers should be further explored by a larger scale clinical trial.

     

Wildlife Conservation on the Rangelands of Eastern and Southern Africa: Past,Present, and Future

Our objective was to assess the status of the large native rangeland mammals in the eastern and southern African countries focusing on conservation strategies that will benefit the animals, their rangeland habitats, and the people who live in this region. Eastern and southern African rangelands are renowned for supporting a globally unique diversity and abundance of large mammals. This wildlife legacy is threatened by changing demographics, increased poaching, habitat fragmentation, and global warming, but there are reasons for optimism. After sharp declines from 1970 to 1990 across Africa, wildlife populations in some countries have subsequently increased due to incentives involving sport hunting and ecotourism. National parks and protected areas, which have been critically important in maintaining African wildlife populations, are being increased and better protected. Over the past 50 years, the number of parks has been doubled and the areas of several parks have been expanded. The major problem is that no more than 20% of the national parks and reserves set aside for wildlife are adequately protected from poaching. The southern African countries where wildlife has recently thrived have robust hunting and ecotourism programs, which economically benefit private landowners. Considerable research shows rural communities dependent on rangelands can be incentivized to participate in large mammal conservation programs if they can economically benefit from wildlife tourism, sport hunting, and the legal sale of animal by-products. Community-based wildlife conservation programs can be economically and ecologically effective in sustaining and enhancing African wildlife biodiversity, including rhinos, elephants, and lions. Low-input ranching wild ungulates for meat and hunting may be an economically viable alternative to traditional range livestock production systems in some areas. However, in many situations, common-use grazing of livestock and wildlife will give the most efficient use of rangeland forages and landscapes while diversifying income and lowering risk.     

Electric resistance as a measure of tree water status during seasonal drought in a tropical dry forest in Costa Rica

Variation in electric resistance of stem tissues was used to measure differences and changes in water status among trees in a tropical dry forest in Costa Rica during the dry season. For more than 30 tree species, stem water content (SWC), measured as electric resistance between nails driven 20 mm deep into tree trunks, correlated well with wood density, saturation water content, dehydration, measured with the pressure chamber, and tree development during drought. At dry sites, SWC was lowest in hardwood trees (characterized by high wood density) and highest in stem-succulent lightwood trees (characterized by low wood density). Among hardwood trees, SWC varied with soil water availability. During the dry season, SWC declined before leaf shedding and increased during rehydration preceding bud break. The time course of seasonal changes in SWC apparently constitutes an indirect measure of variation in the relative water content of outer stem tissues, which determines development of dry-forest trees during the dry season.     

Evaluation of semiochemical toxicity to houseflies and stable flies (Diptera: Muscidae)

BACKGROUND: The housefly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) are cosmopolitan pests of both farm and home environments. Houseflies have been shown to be resistant to a variety of insecticides, and new chemistries are slow to emerge on the market. Toxicities of selected semiochemicals with molecular structures indicative of insecticidal activity were determined against adults from an insecticide‐susceptible laboratory strain of houseflies. The three most active semiochemicals were also evaluated against recently colonized housefly and stable fly strains. RESULTS: Nineteen semiochemicals classified as aliphatic alcohols, terpenoids, ketones and carboxylic esters showed toxicity to houseflies and stable flies. Rosalva (LC₅₀ = 25.98 µg cm^?2) followed by geranyl acetone and citronellol (LC₅₀ = 49.97 and 50.02 µg cm^?2) were identified as the most toxic compounds to houseflies. Permethrin was up to 144‐fold more toxic than rosalva on the susceptible strain. However, it was only 35‐fold more toxic to the insecticide‐tolerant field strain. The compounds generated high toxicity to stable flies, with LC₅₀ values ranging from 16.30 to 40.41 µg cm^?2. CONCLUSION: Quantification of LC₅₀ values of rosalva, citronellol and geranyl acetone against susceptible housefly and field‐collected housefly and stable fly strains showed that semiochemicals could serve as potent insecticides for fly control programs. Copyright © 2010 Society of Chemical Industry     

Photoperiodic control of seasonal development and dormancy in tropical stem-succulent trees

Tropical stem-succulent trees store large quantities of water in their trunks yet remain leafless during the early and mid dry season. In contrast to most other tropical trees, bud break of vegetative buds is not induced in fully hydrated stem succulents between the winter solstice and the spring equinox by leaf abscission, abnormal rain showers or irrigation. Vegetative buds of leafless trees are therefore in a state of endo-dormancy similar to that of temperate perennial plants during early winter. Highly synchronous bud break regularly occurs soon after the spring equinox, often weeks before the first rainfalls of the wet season. These observations suggested that endo-dormancy and bud break might be induced by declining and increasing photoperiods after the autumn and spring equinoxes, respectively. In phenological field observations, we confirmed highly synchronous bud break after the spring equinox in many trees of five stem-succulent species in the northern and southern hemispheres. Shoot growth of potted saplings of Plumeria rubra L. was arrested by a decline in day length below 12 h after the autumn equinox, but continued in saplings maintained in a 13-h photoperiod. Conversely, exposure to a 13-h photoperiod induced bud break of dormant apical buds in saplings and cuttings in January, whereas plants maintained in the natural day length of < 11.7 h remained dormant. Photoperiodic control of endo-dormancy of vegetative buds in stem succulents is thus supported by field observations and experimental variation of the photoperiod. At low latitudes, where annual variation of day length is less than 1 h, bud dormancy is induced and broken by variations in photoperiod of less than 30 min.     

INTRACRANIAL RING ENHANCING LESIONS IN DOGS: A CORRELATIVE CT SCANNING AND NEUROPATHOLOGIC STUDY

This retrospective analysis of 15 dogs with postcontrast ring enhancing brain lesions, each detected by a single Computed Tomography [CT] examination, searched for any association between their CT appearance and the pathologic diagnosis. In a subgroup of these dogs [n = 7] necropsied within 2 days of the last CT scan, we evaluated whether there was any anatomic correlation between the ring zone and the histopathologic features of the lesions. Our study consisted of eight dogs with primary brain tumors [3 meningiomas, 3 astrocytomas, 1 mixed glioma, 1 oligodendroglioma], 4 with metastatic brain tumors [2 fibrosarcomas, 1 mammary carcinoma, 1 melanoma] and 3 with non-neoplastic brain lesions [2 intraparenchymal hemorrhages, 1 pyogranulomatous meningoencephalitis]. The overall size and shape of the contrast enhancing CT lesions, as well as the thickness, surface texture and degree of enhancement of the ring were subjectively evaluated. No association was found between the CT lesion characteristics and the pathologic diagnosis. In the sub-group of dogs euthanatized within 2 days of the CT examination, distinct histologic features which anatomically correlated with the zone of ring enhancement were found in 3 of 7 lesions. The findings of this study are consistent with those of ring-enhancing lesions in people, and indicates that CT ring enhancement is a non-specific phenomenon which can occur in a variety of neoplastic and non-neoplastic lesions in the dog.     

Creating landscape patterns by forest cutting: Ecological consequences and principles

Landscape structural characteristics, such as patch size, edge length, and configuration, are altered markedly when management regimes are imposed on primeval landscapes. The ecological consequences of clearcutting patterns were explored by using a model of the dispersed patch or checkerboard system currently practiced on federal forest lands in the western United States. Thresholds in landscape structure were observed on a gradient of percentages of landscape cutover. Probability of disturbance,e.g., wildfire and windthrow, and biotic components,e.g., species diversity and game populations, are highly sensitive to these structural changes. Altering the spatial configuration and size of clearcuts provides an opportunity to create alternative landscapes that differ significantly in their ecological characteristics. Both ecosystem and heterogeneous landscape perspectives are critical in resource management.     

Effect of bran diet on organic acids in the gastrointestinal tract and apparent digestibility in weanling piglets

Over a period of four weeks 88 piglets of an average weaning weight of 9.5 kg received rations with 2.1, 3.1 and 5.5% crude fibre in the original substance in the form of wheat bran. Between the 42nd and 49th day of life a digestibility investigation was carried out by means of Cr2O3, and on the 42nd and the 63rd day of life the organic acids in the complete gastro-intestinal tract could be ascertained, the causes of which are to be found in the lack of easily soluble carbohydrates (increased passage rate, bran quota). Due to crude fibre, the apparent digestibility of all nutrients decreased, which resulted in a lower live weight on the 63rd day of life. The effect of a bran diet in the alimentary prophylaxis of coli enterotoxaemia is thus furthermore substantiated.