The function of the cranial crest and jaws of a unique pterosaur from the Early Cretaceous of Brazil

The discovery of a previously undescribed pterosaur, Thalassodromeus sethi, yields information on the function of cranial crests and the feeding strategy developed by these extinct flying reptiles. The material consists of a large skull (length: 1420 millimeters, including the crest) with a huge bony crest that was well irrigated by blood vessels and may have been used for regulation of its body temperature. The rostrum consists of two bladelike laminae, the arrangement of which is analogous to the condition found in the bird Rynchops, which skims over the water to catch food, indicating that T. sethi also may have been a skimmer.     

Form and function of retroviral proviruses

Retroviruses have proved to be useful reagents for studying genetic and epigenetic (such as regulatory) changes in eukaryotic cells, for assessing functional and structural relationships between transposable genetic elements, for inducing insertional mutations, including some important in oncogenesis, and for transporting genes into eukaryotic cells, either after natural transduction of putative cellular oncogenes or after experimental construction of recombinant viruses. Many of these properties of retroviruses depend on their capacity to establish a DNA (proviral) form of their RNA genomes as a stable component of host chromosomes, in either somatic or germinal cells.     

Laboratory-based flight performance of the fall armyworm,Spodoptera frugiperda

In late 2018, the fall armyworm(FAW) Spodoptera frugiperda Smith(Lepidoptera: Noctuidae) made its arrival in China and its populations have since proliferated across most of eastern Asia. While S. frugiperda exhibits a considerable dispersal capacity and engages in long-distance migration, there's only scant information on the species' flight capability. Here, we empirically assessed S. frugiperda flight activity under varying climatic conditions using a flight mill. More specifically, under laboratory conditions, FAW exhibited superior flight performance at 20–25°C and 60–90% relative humidity(RH). When quantifying flight performance over five consecutive nights(i.e., 10 h/night), all flight parameters initially increased and then gradually dropped and FAW adults attained a total flight distance, duration and velocity equal to 63.73 km(48.42–94.12 km)(median, quartile range), 24.12 h(20.87–27.73 h) and 2.73 km h~(–1)(2.13–3.33 km h~(–1)), respectively. Our work constitutes a first comprehensive assessment of S. frugiperda flight performance and provides baseline information for future efforts to forecast spatiotemporal changes in its geographical distribution, movement patterns and invasion trajectories. Such can ultimately permit a timely and targeted deployment of area-wide pest management measures against this newly-invasive pest in China and across eastern Asia.     

Enzyme changes in flight muscle correlated with aging and flight ability in the male housefly

Magnesium-activated adenosine triphosphatase activity in the giant mitochondria (sarcosomes) of the flight muscle of aging male houseflies decreases concomitantly with failure in flight as reflected in the loss of wings during the second week of adult life. Preceding the loss of wings, however, there is a rapid decline in the activity of an alpha-glycerophosphate dehydrogenase which is located in the extramitochondrial fraction and is dependent on nicotinamide adenine dinucleotide.     

Wing-assisted incline running and the evolution of flight

Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient wings in feathered theropod dinosaurs and offers a previously unstudied explanation for the evolution of avian flight.     

农业科技宣传的形式、特点与管理问题探讨

介绍了农业科技宣传的主要形式及其特点,分析了农业科技宣传的运行及存在问题,提出了通过学习提高政策水平和科技水平、建立健全监督机制和鼓励全社会关注农业科技宣传的建议.     

Blood trehalose and flight metabolism in the blowfly

The concentration of trehalose in the blood of Phormia regina was found to determine the rate of energy expenditure during flight as reflected in measurements of the wing-beat frequency. Fat body was found to be the source of blood trehalose; either endogenous or exogenous substrates are used for its synthesis.     

浅谈高校图书馆网络化

论述了高校图书馆网络化应由低到高稳步发展、逐步完善，计算机网络技术应用于高校图书馆可解决长期以来围绕其发展的三个矛盾。     

Formation flight of birds

Formation flight of birds improves aerodynamic efficiency. Theoretically, 25 birds could have a range increase of about 70 percent as compared with a lone bird, the advantage being more pronounced when there is a tail wind. A vee formation is required to equally distribute the drag saving, and, contrary to other statements, the lead bird does not necessarily have the most strenuous position. The angle of the predicted vee compares with that observed in nature; stability mechanisms are described which make it easy and natural for the bird to sense optimal formations.     

球面巨型网格结构的构成、支承方式与力学模型

提出了一种新的结构形式——球面巨型网壳结构。文中重点研究了肋环型和凯威特型球面巨型网格主体结构的具体构成形式、几何拓扑关系,总结了相应的形体控制参数;对子结构的形式及其与主体结构的连接进行了分析;描述了自动成形过程。使用Auto- CAD环境下的Visual C 二次开发工具编制了相应的自动成形程序;并对其主体结构支承方式与力学分析模型进行了探讨．本文工作为对该结构体系开展全面系统的力学性能研究提供了良好的前处理基础．     

透视图的改造和新形式

提出了目前的透视图不能作效果图的新论点,并从理论上进行了证明。同时也列出了改造目前透视图的几种方法,通过比较,确立了在透视图上增加带有标尺的图框线和指引线为最好形式。改造后的透视图不但可作效果图,而且也有反求功能。同时也使透视图的形式与其它工程图样相统一。     

Marsilea vestita: Conversion of the Water Form to the Land Form by Darkness and by Far-Red Light

A period in darkness or in continuous far-red light can cause the ferns of the species Marsilea vestita Hook. and Grev. to develop as a land form in a medium which normally allows only the water form to develop. Far-red light is more effective than darkness in causing this conversion. The difference in the quality of light reaching plants growing in water or on land may cause this conversion to occur in nature.     

从加拿大农业科技体制改革及项目评估系统中得到的启示

1998 -1999年笔者赴加拿大列桥研究中心 ,跟随SteveMorganJones主任学习项目管理。期间对加拿大近年来农业科研单位改革的情况作了较多的调研 ,学习了加拿大农业科研项目评估系统(Study ManagementSystem简称SMS) ,结合我国科研管理体系现状得到一定启示 ,提出一些粗浅的建议与同行商榷。     

Adult nutrition affects reproduction and flight performance of the invasive fall armyworm,Spodoptera frugiperda in China

Floral resources, such as carbohydrate-rich nectar or pollen, can bolster fitness and raise reproductive output of adult lepidopterans. Here, we used laboratory experiments to assess how those plant-derived foods impact adult fecundity, reproductive physiology and flight performance of an invasive strain of the fall armyworm, Spodoptera frugiperda(FAW; Lepidoptera: Noctuidae) in China. More specifically, supplementary feeding on bee pollen and honey enhanced FAW flight duration, testis size, ovarian development, longevity and adult fecundity. FAW adults attained the longest pre-oviposition(10.8 days) and oviposition period(6.8 days) and longevity(19.2 days) on 5% acacia honey. Upon access to 2.5% acacia honey and 2.5‰ pine pollen, S. frugiperda attained the highest mating rate(79.7%), fecundity(644.9 eggs/female) and egg hatching rate(82.3%). Feeding on honey further delayed decay of male testes, while ovarian development was enhanced when female moths were allowed access to 2.5% honey and 2.5‰ pine pollen. Upon feeding on 5% honey solution, S. frugiperda engaged in flight over the longest duration(9.5 h), distance(29.9 km) and speed(3.1 km h~(–1)). Honey had a comparatively greater effect on the above parameters than pollen. Our findings help decipher FAW invasion patterns and population dynamics, facilitate the development of nutritional attractants, and contribute to integrated pest management of this newly-invasive pest in eastern Asia.