不同磷化氢浓度下3个不同抗性的小眼书虱品系的完全死亡时间

在(25±1)℃,(75±5)%相对湿度条件下,分别控制100、200、300、400和500 mL/m3的磷化氢浓度,比较研究了抗性倍数分别约为1、5和12倍的小眼书虱3个品系的完全死亡时间.结果表明:在以上相应磷化氢浓度下抗性倍数为1的R1品系的完全死亡时间分别为22 d、19 d、13 d、7 d和7 d.抗性倍数为5的R5品系的完全死亡时间分别为31 d、28 d、22 d、19 d和13 d.对于抗性倍数为12的R12品系,在100 mL/m3的浓度下第31天时仍有存活,在200mL/m3、300 mL/m3、400 mL/m3和500 mL/m3的磷化氢浓度下的完全死亡时间则分别为31 d、28 d、19 d和16 d.     

高温对腐食酪螨的作用研究初报

本文报道了在８５％ｒ．ｈ．和不同高温条件下，杀死腐食酪螨成螨的情况；在５５．０℃时，需８分钟；在５２．５℃、５０．０℃、４７．５℃时，分别需要１０、１５、２５分钟；在４５．ｏ℃、４２．５℃、４０．０℃时，则分别需要２．５、１１、２８小时。     

Association between depressive symptoms and mortality risk in chronic kidney disease.

Objective: Previous examinations of depression as a predictor of mortality in end-stage renal disease have yielded inconsistent findings. We sought to clarify the possible link with mortality by assessing depression at an earlier stage of renal impairment before the uremic disease state and depressive symptoms become highly confounded, and then following patients during the period of disease progression. Design: Prospective design using an assessment of depression before initiation of renal replacement therapy to predict mortality status an average of 81 months later in patients in the early stages of chronic kidney disease. Main Outcome Measures: Mortality status. Results: After controlling for relevant mortality risk factors (i.e., age, gender, presence of diabetes and cardiovascular disease, and potassium level), results of Cox regression analyses indicated that higher levels of nonsomatic depression symptoms were predictive of an increased mortality risk, χ2(1, N = 359) = 8.02, p = .005. Patients with nonsomatic depression scores 1 SD above the mean had an estimated mortality rate 21.4% higher than average scorers in this sample. Conclusion: Clinical implications of these findings point to the importance of assessment and treatment of depressive symptoms in patients with chronic kidney disease. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A cross-validation deletion-substitution-addition model selection algorithm: Application to marginal structural models

The cross-validation deletion-substitution-addition (cvDSA) algorithm is based on data-adaptive estimation methodology to select and estimate marginal structural models (MSMs) for point treatment studies as well as models for conditional means where the outcome is continuous or binary. The algorithm builds and selects models based on user-defined criteria for model selection, and utilizes a loss function-based estimation procedure to distinguish between different model fits. In addition, the algorithm selects models based on cross-validation methodology to avoid “over-fitting” data. The cvDSA routine is an R software package available for download. An alternative R-package (DSA) based on the same principles as the cvDSA routine (i.e., cross-validation, loss function), but one that is faster and with additional refinements for selection and estimation of conditional means, is also available for download. Analyses of real and simulated data were conducted to demonstrate the use of these algorithms, and to compare MSMs where the causal effects were assumed (i.e., investigator-defined), with MSMs selected by the cvDSA. The package was used also to select models for the nuisance parameter (treatment) model to estimate the MSM parameters with inverse-probability of treatment weight (IPTW) estimation. Other estimation procedures (i.e., G-computation and double robust IPTW) are available also with the package.     

Age differences in social preferences among Taiwanese and mainland Chinese: The role of perceived time.

Socioemotional selectivity theory holds that as people recognize the inevitable constraint of time imposed by mortality, their social goals change, motivating them to limit social contacts to those with whom they are emotionally close. This theory was tested among Taiwanese and Mainland Chinese. As predicted, results showed that older adults (aged 60–90 years) in both cultures were more likely than younger adults (aged 18–30 years) to prefer familiar social partners who were most likely to provide emotionally close social interactions. Mainland Chinese, who as a group have shorter actuarial life expectancy, were more likely to prefer familiar social partners than were Taiwanese. These age and cultural differences were eliminated when differences in perceived time were statistically controlled for. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

沼蛤幼虫管道湍流灭杀试验研究Ⅱ:灭杀效果

沼蛤(Limnoperna fortunei)作为典型入侵性底栖动物,可造成管道严重堵塞,威胁技术供水系统正常运转。前期试验研究了致紊材料对管道水力特性的改变,为验证致紊材料对管道沼蛤幼虫灭杀效果,本研究选用水力学试验推荐的4种致紊材料并采用普通和加密两种方式布置在管道中。分别进行了脉动灭杀试验(试验系统流量=0.018 m~3/s)和死循环(系统补给流量≈0 m~3/s)灭杀试验,采样和显微观测统计不同发育阶段幼虫的密度及死亡率。结果表明试验期间沼蛤幼虫基本处于前期壳顶阶段,经过脉动管后死亡方式主要为组织流出、组织脱落和壳体破碎。脉动试验中6 mm孔板对沼蛤幼虫灭杀效果最好,加密布置可以提升大孔径孔板和筛网的灭杀效果。采用幼虫相对体长d*(幼虫体长与Kolmogorov长度尺度之比)衡量致紊材料的灭杀效果,当下游主流区(d*)_(max)0.7时灭杀效果明显。死循环在5 min内可以迅速提高沼蛤幼虫死亡率,之后死亡率基本稳定,所以如能保证幼虫在脉动场中被作用达一定时间,即能对其进行有效灭杀。     

On-farm deaths of dairy cows are associated with features of freestall barns

On-farm death (OFD) of a dairy cow is always a financial loss for a farmer, and potentially a welfare issue that has to be addressed within the dairy industry. The aim of this study was to explore the associations between OFD of dairy cows, housing, and herd management in freestall barns. To achieve the goal, we followed 10,837 cows calving in 2011 in 82 herds. Data were gathered with observations and a structured interview during farm visits and from a national dairy herd improvement database. The hazard of OFD was modeled with a shared frailty survival model, with SAS 9.3 PHREG procedure (SAS Institute Inc., Cary, NC). The study population was 58% Ayrshire and 42% Holstein cows. The median herd size and mean milk yield in the study herds were 116 cows and 9,151 kg of milk per cow per year. The overall probability of OFD was 6.0%; 1.8% of the cows died unassisted and 4.2% were euthanized. Variation in OFD percentage between individual herds was large, from 0 to 16%, accounting for 0 to 58% of all removals in the herds. Keeping close-up dry cows in their own group was associated with higher hazard of OFD [hazard ratio (HR) = 1.37] compared with keeping them in the same pen with far-off dry cows. Higher hazard on OFD was observed when barns had only one kind of calving pen; single (HR = 2.09) or group pens (HR = 1.72), compared with having both of those types. The hazard of OFD was lower if the whole herd was housed in barns or pens that had only 1 type of feed barrier at the feed bunk, namely post-and-rail (HR = 0.51) or a type with barriers between the cow's heads (HR = 0.49), compared with having 2 types. Lower OFD hazard was observed with wider than 340 cm of walking alley next to the feeding table (HR = 0.75), and with housing a whole herd in pens with only 1 type of walking alley surface, specifically slatted (HR = 0.53) or solid (HR = 0.48), compared with having both types. The hazard of OFD was higher with stalls wider than 120 cm (HR = 1.38) compared with narrower stalls. The hazard of OFD was also associated with breed, parity, and calving season. This study identified many factors that contribute to the incidence of OFD of dairy cows. The solutions for reducing on-farm mortality include housing, management, and breeding choices that are most probably herd specific.     

Invited review: The welfare of young calves transported by road

The transport of young calves is a welfare concern. Young calves aged ≤3 mo are particularly vulnerable to compromised welfare, and are at a relatively high risk of morbidity and mortality compared with adult cattle. Calves face several potential challenges to welfare during and after transport, including food and water deprivation, disease, injury, and stress from handling, social mixing, and new environments. The key risk factors identified for poor calf welfare associated with transport include long transport and fasting durations, young age at transport, poor colostral immunity, timing within the calving season, lack of bedding in trucks, and high stocking density. Maximizing calf welfare thus requires a multifaceted approach, such as minimizing transport and fasting durations, transporting at an appropriate stocking density with comfortable bedding, only transporting calves that are healthy and fit, and optimizing pre-transport calf management. More research is needed to understand the effect of transport on the mental or affective state of calves.     

Sire contribution to fertilization failure and early embryo survival in cattle

Despite passing routine laboratory tests of semen quality, bulls used in artificial insemination (AI) exhibit a significant range in field fertility. The objective of this study was to determine whether subfertility in AI bulls is due to issues of sperm transport to the site of fertilization, fertilization failure, or failure of early embryo or conceptus development. In experiment 1, Holstein-Friesian bulls (3 high fertility, HF, and 3 low fertility, LF) were selected from the national population of AI bulls based on adjusted fertility scores from a minimum of 500 inseminations (HF: +4.37% and LF: ?12.7%; mean = 0%). Superovulated beef heifers were blocked based on estimated number of follicles at the time of AI and inseminated with semen from HF or LF bulls (n = 3–4 heifers per bull; total 19 heifers). Following slaughter 7 d later, the number of corpora lutea was counted and the uteri were flushed. Recovered structures (oocytes/embryos) were classified according to developmental stage and stained with 4′,6-diamidino-2-phenylindole to assess number of cells and accessory sperm. Overall recovery rate (total structures recovered/total corpora lutea) was 52.6% and was not different between groups. Mean (± standard error of the mean) number of embryos recovered per recipient was 8.7 ± 5.2 and 9.4 ± 5.5 for HF and LF, respectively. Overall fertilization rate of recovered structures was not different between groups. However, more embryos were at advanced stages of development (all blastocyst stages combined), reflected in a greater mean embryo cell number on d 7 for HF versus LF bulls. Number of accessory sperm was greater for embryos derived from HF than for LF bulls. The aim of experiment 2 was to evaluate the effect of sire fertility on survival of bovine embryos to d 15. Day 7 blastocysts were produced in vitro using semen from the same HF (n = 3) and LF (n = 3) bulls and transferred in groups of 5–10 to synchronized heifers (n = 7 heifers per bull; total 42 heifers). Conceptus recovery rate on d 15 was higher in HF (59.4%,) versus LF (45.0%). Mean length of recovered conceptuses for HF bulls was not affected by fertility status. In conclusion, while differences in field fertility among AI sires used in this study were not reflected in fertilization rate, differences in embryo quality were apparent as early as d 7. These differences likely contributed to the higher proportion of conceptuses surviving to d 15 in HF bulls.     

Efficacy of contact insecticides for the control of the lesser mealworm,Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

The lesser mealworm, Alphitobius diaperinus is a common pest of poultry farming facilities, the presence of which harbors diseases and economic loss, but it also occurs in different types of storage and processing facilities, such as feed mills. In this study, we evaluated the efficacy of three contact insecticides, alpha cypermethrin, spinosad, and pirimiphos methyl, against adults and larvae of A. diaperinus in a series of two bioassays. In the first series of bioassays, mortality rates were determined after 1, 3, 7 and 14 days of exposure on concrete dishes treated with the above insecticides. The results show that all three insecticides were effective for the control of this species, since after 14 days of exposure mortality exceeded 90% for both adults and larvae. Spinosad had a definite advantage over the other two insecticides, providing complete (100%) insect mortality after 14 days of exposure. In the second series of bioassays, the presence of food was evaluated to determine the effects of immediate and delayed mortality. We found that the presence of food in the concrete dishes decreased the levels of delayed mortality of the exposed individuals. All three insecticides showed an increased level of delayed mortality, either with or without food, but mortality did not reach 100% for any of the combinations tested. These results present a valid series of data for creating a standardized means of control against this pest that has beset poultry facilities for years.