对Apriori算法的研究及改进

关联分析是数据挖掘的本质体现,关联规则挖掘就是寻找给定的大量数据项集之间存在的某种规律的过程。Apriori算法是关联规则中最重要的一种挖掘频繁项集的算法,但是它也存在一定的不足。目的为了提高挖掘效率。方法采用实验的方法,在经典Apriori算法的基础上进行改进。结果证明改进的Apriori算法性能优于经典的Apriori算法,尤其是在交易事务条数比较多的情况下,效果更加明显。结论是改进的算法在计算支持度个数时,每次不需要扫描全部数据库,只需要在精简的数据库表中扫描各项所在的行就可以了,大大节省了时间;支持度计数的统计也比较容易,也不会产生过多的冗余,可以在很大程度上降低挖掘的复杂度,提高挖掘算法的效率。     

Circadian and seasonal variability and influence of sex and race on eight clinical chemistry parameters in budgerigars (Melopsittacus undulatus, Shaw 1805)

The aim of the study was to investigate if there is a clinically relevant influence of daytime or season and if there are sex-dependant differences in some frequently determined clinical chemistry parameters. The study was performed with 99 1.5- to 2-year old healthy budgerigars of three races. A harmonic regression analysis was performed taking into account linear and cyclic trends over the year. Correlations were investigated by the calculation of Spearman correlation coefficients. Summarizing, it can be said that some circadian, seasonal, as well as sex- and race-dependant influences have been shown. However, although the differences are statistically significant, they were too small to have an impact on clinical decision making. As clinical chemistry results are in practice independent from the influence factors investigated, their meaning and use as a diagnostic tool is further substantiated.     

Sense and sensitivity--designing surveys based on an imperfect test

Designing a survey to detect the presence of a disease is complicated if the test used to detect the disease has non-perfect sensitivity and specificity. This paper gives two new approximations that simplify such a task. The first gives the cumulative probability distribution of the number of apparently diseased animals detected in the survey and the second gives the probability that no diseased animals are detected if the test used has 100% specificity. Both approximations can be used to determine confidence limits for the true prevalence.

The main purpose of the approximations is to determine the number of animals that need to be tested to be confident that a herd is free of disease, and then to determine the number of herds that need to be tested to demonstrate area freedom. One approach to such an area survey has been to classify each herd as diseased or not based on the number of reactors found in the herd, and then to use the number of herds classified as diseased to determine the area’s status. The paper points out that basing the decision simply on the magnitude of the maximum observed within-herd reactor proportion results in a more accurate survey for the same number of animals and herds tested.     

Reference values for serum biochemical parameters in free-ranging harp seals

Background — The harp seal (Phoca groenlandica) is one of the most important predators in the Northeastern Atlantic ecosystem. Establishing biochemical reference intervals is important for evaluating the health status of harp seals kept in captivity and for evaluating the effects of environmental changes on the health of populations in the wild. Objective — The purpose of this study was to determine reference values for serum biochemical parameters in wild adult harp seals using readily available current methods. Methods — Blood samples were obtained from 14 adult female harp seals and 9 suckling pups on the pack ice of the Greenland Sea in early March 1998. Seven seals were humanely killed on the ice by permission of the Norwegian Directory for Fisheries and in conjunction with several other research projects. The seals were sampled within 15 minutes postmortem. Remaining seals were captured alive and sampled via the extradural intravertebral vein. Serum biochemical parameters were measured using a Technicon Axon analyzer and included electrolytes (sodium, chloride, potassium, magnesium, and calcium), substrates (free fatty acids, triglycerides, fructosamine, and glucose), end products (urea and uric acid), and proteins (total protein, globulins, and albumin). Serum protein electrophoresis also was done. Data were tested for normality and reference limits were calculated as mean ±1.96 × SD. Results between groups were compared using 2‐tailed t‐tests. Results — Serum levels of glucose and triglycerides were lower, but serum levels of urea were higher in dead animals than in animals that were captured alive. Serum levels for 7 of 17 parameters were significantly different in pups compared with adults. Separate reference intervals were calculated for adult seals and seal pups. Conclusion — Both sampling method and age should be considered when evaluating the results of analysis of serum parameters in wild and captive harp seals.     

对分区间法的应用

对对分区间法进行详尽的论述,论证区间端点即为基本列。并说明以基本列必收敛为公理的合理性。使用“对分区间法”可以完成许多理论上的证明。对分区间法体现了分析方法的规范性和技巧性,在理论和实践中有着广泛的应用。     

Sildenafil citrate therapy in 22 dogs with pulmonary hypertension

BACKGROUND: Pulmonary hypertension (PH) is a disease condition characterized by abnormally increased pulmonary artery pressures and often is associated with a poor prognosis. Sildenafil is a phosphodiesterase inhibitor that causes pulmonary arterial vasodilation and reduction in pulmonary artery pressures. HYPOTHESIS: Treatment with sildenafil will improve echocardiographic determinants of PH in dogs, while also improving quality of life and survival. ANIMALS: Twenty-two dogs with clinical and echocardiographic evidence of pulmonary hypertension. METHODS: A retrospective study evaluating the effects of sildenafil on physical examination, ECG and radiographic findings, blood pressure and echocardiographic findings of PH, clinical score, and outcome was completed. PH was defined as a peak tricuspid regurgitation flow velocity > or = 2.8 m/s or a peak pulmonic insufficiency flow velocity > or = 2.2 m/s. RESULTS: Sixteen of 22 dogs with PH were elderly females of small body size. Their clinical score was significantly improved (P = .0003) with sildenafil treatment, but physical examination findings remained unchanged. Heart rate, respiratory rate, vertebral heart size, ECG heart rate, and systolic blood pressure did not change significantly with sildenafil treatment (P > .05). Peak tricuspid regurgitation flow velocities did not change significantly with the treatment of sildenafil, but selected systolic time intervals were significantly improved. Survival times for all dogs ranged from 8 to > 734 days. CONCLUSIONS AND CLINICAL IMPORTANCE: Sildenafil did not significantly lower the degree of measurable PH in dogs. Clinical improvement and increased quality of life was seen with sildenafil treatment, despite lack of significant change in other variables.     

‘酒棉8号’棉花新品种膜下滴灌栽培示范

选用新疆、辽宁和甘肃的14个棉花新品种,以‘新陆早7号’为对照,结合膜下滴灌技术进行了适宜民勤农业生态环境种植的棉花新品种的筛选及膜下滴灌丰产栽培技术的研究.结果表明:‘酒棉8号’新品种光合速率较高(9.60μmol.m-2.s-1),蒸腾速率较低(102.6g.m-2.h-1),平均单铃4.46g,早熟性好,籽棉产量高,该品种在栽培密度为20 000株.(667m-2)、控制株高44.6cm左右、平均单株有效铃数4.3个、全生育期内控制膜下滴灌量为240m3.(667m-2)的情况下产量最高,是民勤县具有推广潜力的棉花膜下滴灌栽培新品种.     

融合梯度幅值和置信度的鸡蛋裂纹图像检测

提出一种融合梯度幅值和置信度的鸡蛋裂纹检测新方法.采集褐壳鸡蛋的裂纹图像,运用提及边缘检测算法获取感兴趣区域图像,采用最大边界算法挑选边界轮廓,融合二者获取裂纹区域图像.对3种典型鸡蛋裂纹图像进行边缘检测新方法与传统边缘检测算子(Log算子、Sobel算子及Canny算子)对比试验,结果表明:融合梯度幅值和置信度的鸡蛋裂纹检测新方法能够克服固定阈值适应性较差的缺陷,提高检测准确率,在消除噪声、增强弱边缘信息方面优于传统边缘检测算子.     

Improving Genetic Engineering Secondary Education Through a Classroom-Ready Online Resource

Genetic engineering has long been used in food production in the United States. However, consumers' science literacy in genetic engineering is poor. Teacher knowledge, time, and resources are lacking in science curriculums on genetic engineering. Through interviews conducted with six high school agriculture teachers we show how a new online resource, The Journey of a Gene, addresses these barriers to help improve their knowledge and increase time spent on genetic engineering. The positive outcomes support funding for genetic engineering education. Education is key to help consumers make informed purchasing decisions and societal decisions about advancing genetic engineering research.     

大学语文与大学生心理素质提高

大学语文在秉承中学语文教学提高学生对祖国语言文字理解和应用能力的优良传统的同时,应着力提高当代大学生的心理素质,培养潇洒旷达的人生态度、百折不挠的个性、直面挫折的勇气及高度的自信心等,以使他们能够妥善处理在学习、生活、求职等领域遇到的困难和挫折。