Untersuchungen zur antigenetischen Verwandtschaft aviärer Reoviren aus Broilern mit Malabsorptionssyndrom (MAS)

Avian reoviruses (ARV) are supposed to play an important role in development of malabsorption syndrome (MAS) in broiler flocks. By seriously affecting weight gain, considerable economic losses occur. The present study deals with ARV which had been isolated from broilers with MAS despite vaccination of parental flocks. Thus, the question arose if the isolates were antigenic variants which could bypass protection by vertically transmitted maternal antibodies. For examination, cross neutralization tests were chosen. To gain repeatable results for all ARV isolates, a plaque reduction assay including an immunohistochemical staining method was adapted to ARV. Thereby, different ARV strains induced three distinguishable plaque types on CEL and CEF cells. The examinations on CEL cells included hyperimmune sera raised against vaccine strain S1133, against a flock-specific vaccine strain and against four MAS-strains isolated in the "Klinik für Vögel". Additionally, four pooled serum samples from parental flocks were tested. Besides the vaccine strain S1133, eleven ARV strains/ isolates were examined. The neutralization capacity of hyperimmune sera differed considerably. Sera which were raised against the MAS-isolates showed a clearly reduced neutralization capacity compared to serum a-S1133. ARV strains displayed a considerable antigenic heterogeneity with clear differences to the reference strain S1133. Concurrently, an extended cross reactivity occurred. Remarkably, vaccine strain S1133 was neutralized best by every used serum, whereas the MAS-isolates resisted neutralization to a noticeable extent. These results led to the consideration as to whether the used testing system purely reflects antigenic relatedness or if it is fundamentally affected by the host cell used. Therefore, neutralization examinations with three selected strains which were obtained from four different tissues followed: CEL and CEF cells, embryonic liver and embryonic gut. Additionally, resulting virus stocks of one MAS isolate were neutralized comparing the reaction pattern on CEL and CEF cells. Thereby, the reaction pattern of strain S1133 stayed constant, whereas one MAS isolate was neutralized to a greater extent when it was obtained from embryonic instead of cellular origin. Hence, the formerly noted dominance of the S1133 strain was overcome when a CEL cell system was used. On a CEF cell system, these differences did not occur. In order to determine antigenic relatedness of MAS isolates, R-values were calculated and interpreted by a definition given for foot-and-mouth-disease . Thus, MAS isolates were defined as minor and major subtypes of strain S1133 and were all closely related. For strategies of controlling early ARV infections, especially the partial resistance to neutralization and the lesser immunogenicity of the existing MAS isolates are of great importance. It can be assumed that the inclusion of novel ARV isolates in vaccination protocols will not guarantee complete protection since ARV will retain the ability to escape the systemic humoral immune response. Possibly, stimulation of the cytotoxic immune response provides some potential for controlling early ARV infections. Nevertheless, thorough hygiene protocols remain indispensable and should include regular checking of disinfectants, particularly their capacity to degerminate existing ARV variants

Nitrogen Application Rate Effect on Nitrate-Nitrogen Concentration and Loss in Subsurface Drainage for a Corn-Soybean Rotation

Excess precipitation in Midwest agricultural production areas is often removed artificially via subsurface drainage systems that intercept and divert it to surface waters. Nitrogen (N), either applied as fertilizer or manure or derived from soil organic matter, can be carried as nitrate with the excess water in quantities that may have deleterious effects downstream. A field study was initiated in 1989 in Pocahontas County, Iowa, on 0.05 ha plots of glacially derived clay loams. The objective of this three-phase study was to determine the effect of N application rate on NO3-N concentration and loss in a corn-soybean rotation over a wide range of weather conditions. Nitrogen-rate treatment phases with five seasons each (six for phase II) were imposed on subsurface-drained, continuous-flow-monitored plots over a 16-year period. Phase I N rates ranged from 0 to 168 kg N ha-1 in 56 kg N ha-1 increments. Separate plots were used for each crop in phase I, and significant NO3-N concentration differences were not observed between corn or soybean plots; this led to combining both crops in a split-plot configuration for phases II and III to study system effects. Phase II N rates ranged from 45 to 179 kg N ha-1 in 45 kg N ha-1 increments. Phase III was limited to two rates, 168 and 252 kg N ha-1. Average yearly flow-weighted NO3-N concentrations ranged from 3.9 mg L-1 (45 kg N ha-1, 1995) to 28.7 mg L-1 (252 kg N ha-1, 2001). Average flow-weighted NO3-N concentrations (in mg L-1) ranked by N rate were: 23.4 (252), 13.2 (179), 15.5 (168), 11.9 (134), 11.7 (112), 8.1 (90), 9.5 (56), 5.7 (45), and 8.9 (0). Losses were precipitation dependent and were reflective of individual seasons and rates imposed. Average flow-weighted NO3-N losses (kg ha-1) ranked by N rate and by phase were: 58 (168), 68 (112), 48 (56), 50 (no N) for phase I; 8 (179), 15 (134), 19 (90), 7 (45) for phase II; and 49 (252), 32 (168) for phase III. Results indicate that concentrations generally increased with rate; the effect on losses was variable due to disparity in drainage volumes among years. Corn yield during all periods showed a strong correlation between N rate and yield. As N rate increased, yield increased. It should be noted that at least 50% of the years showed limited yield response to N application above the next to the highest rates. To achieve average NO3-N concentrations less than 10 mg L-1 (USEPA drinking water standard) in subsurface drainage at this site, N application rates would need to be less than 112 kg N ha-1. Rates currently recommended for this area range from 112 to 168 kg N ha-1. Results from this study have significant implications for N fertilizer management and subsurface drainage NO3-N loss to surface waters in the state, the Mississippi River, and the Gulf of Mexico

Characteristics of flight simulator visual systems

The physical parameters of the flight simulator visual system that characterize the system and determine its fidelity are identified and defined. The characteristics of visual simulation systems are discussed in terms of the basic categories of spatial, energy, and temporal properties corresponding to the three fundamental quantities of length, mass, and time. Each of these parameters are further addressed in relation to its effect, its appropriate units or descriptors, methods of measurement, and its use or importance to image quality

Relación entre la memoria de trabajo y el desempeño en matemáticas

This document is the result of an investigation carried out in the Colombian educational context, through a descriptive correlational study that aims to determine the relationship between working memory and performance in mathematics, with the participation of 300 third grade students from primary located in two different contexts, 149 of the I.E. Bolívar de Ubaté and 151 of the I.E. Technician Sacred Heart of Jesus of Chiquinquirá. For the analysis of the working memory variable, two neuropsychological tests were applied, which are the ordering of letters and numbers (Wechsler, 2014) and the Inverse Digit Test (Wechsler, 1987), and for the variable academic performance in mathematics, the grades recorded in the student's academic record; Subsequently, a neuropsychological intervention is designed taking into account the results obtained, which show that there is a moderate correlation of the variables.El presente documento es el resultado de una investigación llevada a cabo en el contexto educativo colombiano, por medio de un estudio descriptivo correlacional que tiene como objetivo determinar la relación que existe entre la memoria de trabajo y el desempeño en matemáticas, con la participación de 300 estudiantes de grado tercero de básica primaria ubicados en dos contextos diferentes, 149 de la I. E. Bolívar de Ubaté y 151 de la I.E. Técnico Sagrado Corazón de Jesús de Chiquinquirá. Para el análisis de la variable de memoria de trabajo se aplicaron dos pruebas neuropsicológicas que son el ordenamiento de letras y números (Wechsler, 2014) y la Prueba de Dígitos inversos de (Wechsler, 1987), y para la variable de desempeño académico en matemáticas, las notas registradas en el historial académico de los estudiantes; posteriormente, se diseña una intervención neuropsicológica teniendo en cuenta los resultados obtenidos y que demuestran que existe una correlación moderada de las variables

Fair Value and Fair Price in Corporate Acquisitions

In statutory corporate acquisitions, dissenters\u27 rights entitle shareholders of acquired corporations to obtain a fair value for their consideration, while common-law fiduciary duties ensure that such shareholders receive a fair price in the transaction. Courts, however, have had difficulty defining and measuring fair value and fair price, leaving this area of the law in disarray. This Article reviews the current framework of appraisal rights and fiduciary duties and proposes refined definitions of fair value and fair price that are based on attractive moral and economic values widely shared by society. The proposal respects the expectations of shareholders and provides guidance for the proper measure of valuations in acquisitions

Fair Value and Fair Price in Corporate Acquisitions

In statutory corporate acquisitions, dissenters\u27 rights entitle shareholders of acquired corporations to obtain a fair value for their consideration, while common-law fiduciary duties ensure that such shareholders receive a fair price in the transaction. Courts, however, have had difficulty defining and measuring fair value and fair price, leaving this area of the law in disarray. This Article reviews the current framework of appraisal rights and fiduciary duties and proposes refined definitions of fair value and fair price that are based on attractive moral and economic values widely shared by society. The proposal respects the expectations of shareholders and provides guidance for the proper measure of valuations in acquisitions

Global Cities as Centers of Cultural Influence: A Focus on Istanbul, Turkey

In different eras, cities such as Babylon, Athens, Rome, London, Madrid and Paris have been highly influential in the development of world culture. In the Fordist and Post-Fordist periods, the primary global culture transmitters have been centered in New York, Los Angeles, Paris, Tokyo and London. As the world becomes increasing more connected and different ‘geographies’ develop, it is inevitable that new global cultural centers will surface to challenge, replace or augment these existing centers. Some of the driving forces behind the predominance of global cultural transmittal centers are the existence of a vibrant and substantial cultural economy, the high level of connection with the global cultural network and the character/level of capital accumulation within these cities. A possible candidate for one of these new cultural centers could be Istanbul due to: (1) the recent regional changes in the economic and geo-political climate; and (2) its unique geographical location, being at the crossroads of Europe, the Middle East and Central Asia. This paper will explore the role of global cultural centers, the importance of a city’s cultural economy, and the position/potential of Istanbul within the evolving global culture