Retinal degeneration in nine Swedish Jämthund dogs

The Jämthund is the fourth most common breed in Sweden with approximately 1600 pups registered each year. Although it has been known that some adult dogs go blind, so they cannot hunt, the Jämthund dog has historically not been screened for hereditary eye diseases. This report describes nine Swedish Jämthund dogs with retinal degeneration. These dogs represent all Jämthund dogs diagnosed with progressive retinal atrophy (PRA) by the Swedish Eye Panel and registered with the Swedish Kennel Club from January 1998 to September 2008. The dogs were examined with indirect opthalmoscopy and slitlamp biomicroscopy. Additionally, electroretinograms (ERGs) following ECVO guidelines were performed in two dogs (one affected and one normal) and the eyes from three affected dogs were examined by light‐microscopy postmortem. Typical findings were bilateral symmetric generalized retinal degeneration with tapetal hyper‐reflectivity, attenuation of blood vessels and pigment clumping in the nontapetal fundus. These retinal findings progressed with time in two dogs after re‐examination. Visual impairment, especially under dim light conditions, was observed in the affected dogs. ERG from one affected dog showed profoundly reduced rod responses, whereas cone responses were better preserved. Microscopic changes in the eyes from three dogs were characterized by a severe diffuse predominantly outer retinal degeneration and atrophy. Re‐sequencing of the prcd‐gene for eight of the nine investigated dogs revealed that none of the individuals carried disease allele that has been associated with prcd‐PRA in other breeds. In conclusion, ophthalmoscopic, electroretinographic, and light‐microscopic alterations observed in nine Jämthund dogs were compatible with PRA. The prcd mutation was excluded as a cause of this retinopathy.     

An assessment of catches and harvest of recreational shore angling in the north of Portugal

Abstract  Recreational shore angling in the Atlantic Ocean between Moledo and Aveiro (Portugal) was examined using roving creel surveys (March/September 2001). Cooperation was high (90% of 2310 anglers approached). At least 39 species of fish were caught at a rate of approximately 0.5 fish angler h⁻¹. An estimated 7319 kg of Dicentrarchus labrax (L.), with 45.6% below the minimum legal size, and 2040 kg of sea breams (genus Diplodus ), correspond to 5.75% and 1.19% of the commercial landings in the same geographical area, respectively. The results shed light on a number of issues relevant to integrated coastal management, including temporal and spatial distribution of fishing effort, species caught, sizes of fish, catch rates, and factors influencing catches and angler satisfaction. Whilst the results suggest that the catches of sea breams and sea bass by day-time recreational shore angling in northern Portugal are small compared with commercial fishing, other recreational activities, such as boat fishing and spear-fishing, must be assessed.     

在电工教学中推广“行为引导型”教学法的研究

“行为引导型”教学法倡导学生参与“教与学”的全过程。具有激励学生学习和焕发学生内在学习动机的功能。在电工教学中推广“行为引导型”教学法要做到转变教学思想，创设开放性的课堂环境，深入挖掘整合教材。     

Study of Lightning Impulse Breakdown Voltage Correction of PositiveRod-Plate Short Air Gaps on Altitude

The air pressure of the high altitude condition in the artificial climate chamber is simulated, and the laboratory investigation of positive rod plate lightning impulse discharge performance were carried out on the short air gaps of 200 mm, 300 mm and 450 mm according to the test method demanded in IEC 60.1. Based the tested results, it is put forward that the positive lightning impulse breakdown voltage of a short air gap at the air pressure of the high altitude district is a power function of the air pressure with a special index less than 1, which indicates that the effect of the air pressure on the breakdown voltage decreases by 8.7% with the increase of the altitude by 1 kilometer. According to the theoretical analysis, it is proposed that the air pressure suggests the comprehensive changes of the basic atmospheric parameters of the temperature, the reltive air density and the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the absolute humidity, thus it could be used as the characteristic variable which expresses the effect of the atmospheric condition on the breakdown voltage of an air gap.     

我国木材干燥设备市场亟待技术规范与正确导向

本文列举了我国木材干燥设备市场中大量技术混乱的事实，有针对性地提出了技术规范的依据，并就如何从技术与体制创新、木材干燥方法、木材树种、干燥设备、干燥工艺、配套系统等方面进行正确引导进行了探讨。     

Internal fracture fixation

Over the past decade, many improvements to small animal internal fracture fixation have been developed, including improved fixation techniques and a more diverse selection of implants. The understanding that appropriate fixation selection is based on a plethora of biologic, mechanical, and clinical factors has also emerged. Classically, the methods of internal fracture fixation have used pins, wires, screws, and plates to rigidly stabilize fractures that have been anatomically reduced with significant disruption to the biologic fracture environment. Newer methods attempt to minimize trauma to the soft tissues surrounding a fracture and promote biologic osteosynthesis using such implants as interlocking nails and plate-rod fixations. This review provides an overview of both the traditional and current principles of small animal internal fracture fixation.     

基于鱼类上溯行为的导鱼堰设计与效果评估

河道内鱼类上溯路径不唯一,聚集位置更是难以预测,对鱼类上溯行为进行有效引导有助于提升过鱼设施进口的效率。为此,该研究提出了一种导鱼堰的概念和设计方法,结合姚家坪水电站的过鱼设施,利用流场三维数值模拟、鱼类洄游（active fish migration,AFM）模型和实鱼试验对导鱼堰的效果进行评估。结果表明：姚家平水利枢纽工程的导鱼堰上下游水面落差为0.36～0.40 m,过堰水流流速可达1.5～2.8 m/s,形成阻鱼的屏障,并在导鱼堰下游侧形成了诱导鱼类向集鱼渠进鱼口游动的唯一低流速上溯通道,鱼类聚集点趋于唯一,验证了导鱼堰方案的合理性。利用鱼类洄游模型对导鱼堰的导鱼效果进行预测,结果表明,下游高水位和低水位2种工况下,90%以上的鱼类游动路径均表现出相似的规律,鱼类沿河道右岸和导鱼堰下游侧的低流速通道上溯,并最终聚集在集鱼渠的进鱼口处。放鱼试验中试验个体全部进入集鱼渠,结果进一步证实导鱼堰可以有效引导鱼类游动路线,并在集鱼渠进鱼口处形成唯一的聚集区。本文提出的导鱼堰丰富了生态水工建筑物的形式,可为过鱼设施进口的水力设计及下游河道的局部整治提供参考。     

机用虎钳的快速夹紧装置设计

分析了传统机用虎钳装夹费时费力、效率低的缺点,并有针对性地设计了一种快速夹紧装置。阐述了该装置的结构和工作原理,并对其中的关键零件夹紧圆杆和弹性夹套进行了优化设计,取得了良好的效果。     

某无人直升机发动机曲轴轴承润滑性能分析

在分析内燃机曲柄连杆动力学和曲轴动力润滑的基础上,建立该系统的动力学与流体动力润滑耦合的动力学分析模型。利用AVL Excite动力学分析软件,以双缸四冲程水冷活塞发动机二支撑方案与三支撑方案为研究对象,通过对其主轴承油膜压力进行计算分析,得出曲轴三支撑方案主轴承油膜边缘压力小于100MPa,满足无限寿命要求。     

香料线滤棒爆口探索及其解决方案研究

为解决香料线滤棒(橙味香料)的爆口问题,进行滤棒成型试验。结果表明:橙味香料中的桔子油和甜橙精油会溶解滤棒搭口粘合剂热熔胶,从而引起滤棒爆口。针对此问题,采用了搭口冷热双胶线技术和伺服同步可调胶量的泵压式供胶系统,并结合对不同厂家提供的冷胶进行筛选,最终有效地解决了橙味香料引起的滤棒爆口。同时,为滤棒爆口和高透成形纸渗胶2个技术难题提供了解决思路。