通过免疫控制猪伪狂犬病

猪伪狂犬病（ＰＲ）又称阿捷申氏病（ＡＤ）是对全世界养猪危害最大的猪病之一,本病可以多种方式传播,最常见的是母猪传给仔猪。肉猪（生长猪）感染后症状不明显,但被认为是本病重要的保毒宿主和传染来源。本病在国内,尤其是近十年来已传遍了二十多个省市（区）,引起...     

猪水肿病的综合防制

猪水肿病(ED)是由致病性溶血性产肠毒素大肠杆菌引起断奶仔猪以突然发病,运动障碍,叫声嘶哑,胃壁、结肠系膜、眼睑部和全身水肿为特征,与营养因素密切相关的传染性疾病。1950年后,欧洲和美洲的集约化养猪业相当发达,水肿病流行较重,当时研究认为,全价饲料的生产和应用与水肿病发病率的增长呈平行关系。我国北京地区于1956年首次报道本病发生,之后在国内各地陆续报道。本病呈地方性流行,发病率为5%～15%,个别地区可达30%,病死率90%以上,是目前和将来一段时间内危害仔猪育成的重要疾病之一。1病原本病发现之初,只是描述了症状,未能找到病原。…     

猪水肿病的预防和治疗

猪水肿病是由产肠毒素大肠杆菌引起的传染病,多发于断奶后营养状况良好的仔猪,患猪出现水肿症状后治愈率较低。1猪水肿病诊断要点断奶后发育良好的仔猪突然卧地不起,眼睑水肿,伴有神经症状;剖检发现胃贲门和大弯部黏膜下水肿、肠系膜水肿,可初步诊断为本病。诊断时应注意本病与链球菌病、猪瘟、传染性胸膜肺炎或弓形体病等混合感染。2猪水肿病的治疗应标本兼治,即采取消肿解毒、抗菌消炎和全群治疗。消肿解毒强心利尿、降低颅内压、缓解神经症状和组织水肿、清理细菌毒素。口服硫酸钠15克,肌注速尿10mL,静注10%氯化钙5mL、50%葡萄糖50mL、…     

猪弓形体病的诊断与防治

猪弓形体病又称弓状体病、弓浆虫病和毒浆虫病，是由龚地弓形体(Toxoplasma gondii)引起的一种人畜共患的寄生虫原虫病。临床常称“无名高热”病，以高热稽留、呼吸及神经系统症状、皮肤发绀和妊娠母畜的流产、死胎、胎儿畸形为特征。自于恩庶1955年首次在福建发现本病流行以来，随后又在上海、湖北、北京、辽宁、云南、江苏等地的“无名高热”病猪体内分离到弓形虫。近年来，本病常呈暴发流行，给养猪业造成了巨大的经济损失．并且猪肉内含有弓形虫，如生肉类或污染肉类被人食用，就可能传染给人，威胁人类健康。现就四川省某规模化种猪场发生本病的诊治情况报告如下。     

猪弓形体病的防治

猪弓形体病（ｔｏｘｏｐｌａｓｍｏｓｉｓ），又称猪弓浆虫病，是由龚地弓形体寄生在猪体组织细胞中引起的一种人畜共患寄生虫病。猫是本病传播的关键。妊娠母猪感染后表现流产，产死胎、弱胎或畸形胎儿；生长肥育猪持续高热；仔猪常呈现神经症状。本病分布非常广泛，各地...     

猪变应性胃溃疡的防治

随着现代化养猪业的发展，猪胃溃疡病也逐年增加，不仅欧美日本等先进养猪国如此，我国近几年有资料报道，猪屠宰时消化性溃疡检出率占２２．６％，而且以变应性胃溃疡为主。１猪变应性胃溃疡的病因、症状及病理１．１病因本病病因比较复杂，尚不十分清楚。但与饲料、饲养...     

一起猪传染性萎缩性鼻炎的诊治

猪传染性萎缩性鼻炎,是由支气管败血波氏杆菌引起的猪的鼻腔内感染症。本病的传播是通过病猪或带菌猪的鼻汁飞沫直接或间接接触而引起的,可感染各种类别和年龄的猪。传染性极强,患病率高,但死亡率低。其危害主要是降低增重和饲料转化率,给生产者造成很大的经济损失。笔者于1999年4月初于某一个体养猪场发现本病。现将诊治情况报告如下。1　发病情况张家口郊区某个体养猪场从外地引进一头种公猪,由于没有进行隔离观察,而引起本病在场内的流行。此种公猪在引进时,就呈现打喷嚏,将鼻端向食槽、猪栏上摩蹭,鼻腔有脓性鼻汁等症状,但由于怀疑是在…     

基于BP神经网络的大豆叶片病害诊断模型的研究

本文以大豆叶片为研究对象,主要针对大豆灰斑病、霜霉病和细菌性斑点病进行诊断。首先,在东北农业大学教育部大豆生物学重点实验室的实验基地培育灰斑病、霜霉病和细菌性斑点病的纯正样本,然后通过对病斑特征的分析,确定病斑特征与病害种类的关系,建立大豆叶片病害的BP神经网络诊断模型。测试结果表明,针对轻度病害,灰斑病、霜霉病、细菌性斑点病和其它病害的识别精度分别为88.75%,87.50%,87.50%,85.00%;中度病害识别精度分别为91.25%,90.00%,91.25%,88.75%;重度病害识别精度分别为93.75%,92.50%,93.75%,92.50%。     

猪链球菌病的流行及防制

１９９８年以来，我们从山东和河南部分地区送检的５００多猪病例中分离到２０多株链球菌。经分析发现，本病的流行，表现形式及病原学方面发生了新的变化。现总结如下。１　流行情况各种日龄、品种猪均易发病，小到哺乳仔猪，大到已使用几年的种猪都能发生本病。发病季节不明显，一年四季均可发生。有的是链球菌单独引起发病，如河南有一例，猪瘟防疫比较科学，但５０～６０日龄杜长大外三元杂交猪暴发此病；有的与猪瘟、肺疫、喘气病、传染性胸膜肺炎和弓形虫其中的一种或几种并发或继发，如在山东省大部分地区。２　临床症状及病理变化脓…     

宝应地区猪猝死症“调查与防制

近几年来 ,我县生猪中多次发生一种以突然发病、病程短、死亡快为特征的疾病 ,俗称“猝死症”。我们通过流行病学调查 ,结合实验室检查 ,确诊本病的主要病原为魏氏梭菌 ,确诊为猪魏氏梭菌病。经采取综合防制措施 ,取得了较显著控制效果。现将有关情况报告如下。1　流行病学特点1 .1　发病情况　　本病在我县最早于 1 993年发生 ,几年来 ,全县 2 9个乡镇共有生猪 2 62 8头发病 ,死亡2 3 83头 ,死亡率 90 .7%,使用多种抗生素及磺胺类药物治疗 ,效果均不理想。1 .2　发病特点　　本病多呈零星发生 ,无明显的区域性 ,亦无明显的季节性 ,但在春秋…     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).