Mean-field theory for scale-free random networks

Random networks with complex topology are common in Nature, describing systems as diverse as the world wide web or social and business networks. Recently, it has been demonstrated that most large networks for which topological information is available display scale-free features. Here we study the scaling properties of the recently introduced scale-free model, that can account for the observed power-law distribution of the connectivities. We develop a mean-field method to predict the growth dynamics of the individual vertices, and use this to calculate analytically the connectivity distribution and the scaling exponents. The mean-field method can be used to address the properties of two variants of the scale-free model, that do not display power-law scaling.Comment: 19 pages, 6 figure

Organic livestock production - trapped between aroused consumer expectations and limited resources

Literature reviews reveal that the implementation of organic standards have failed to clearly improve status of animal health and welfare on many farms in comparison to conventional production. The a huge variability with respect to this issue between organic farms indicate profound discrepancies between claim and reality of organic livestock farming. Thus, the hypothesis that the implementation of minimum standards will automatically provide benefits for the issue of animal health and welfare has been refuted by farm practice. As a consequence, organic farmers and retailers can no longer stick to the claim that organic products of animal origin are of higher value with respect to the issue of animal health and welfare. Reasons for the limited effects of the organic standards are multi-factorial and assumed to be farm specific in the fist place. On the other hand, limited availability of resources such as nutrients, labour time and investments within organic farm systems together with a high pressure on the production costs by retailers make any improvments very difficult. In order to preserve the credibility of organic agriculture and the confidence of the consumers in organic products there is a need for more transparency and for a change in the paradigm from a standard-oriented to an output-oriented approach. Credible information about the specific level of product and process qualities emerged by each farm has to be provided. Simultaneously, a high level of animal health and welfare has to be honoured by premium prices to cover the additional costs and efforts that are needed to improve the current situation

The University as a Pluralistic System: The Case of Minority Faculty Recruitment and Retention

Recently there has been considerable emphasis placed in higher education on the recruitment and retention of minority faculty. There is an expanding literature indicating the problems relating to the inadequate pool of such faculty and strategies and approaches related to effective recruitment and retention.[1] It is apparent that there is considerable interest in this area. Given the predicted demographic patterns and characteristics in the population during the remainder of this century, it is understandable that colleges and universities are pursuing a more diverse faculty. The recruitment and retention of minority faculty, however, is only one component -- though a critically important one -- of the total university environment. The extent of effectiveness in this area will depend upon the totality of the other components in which it is embedded and that characterize the university as a whole

Sense and sensibilities

There are many aspects relating to our profession that lead to varying degrees of inner and outer conflict. These have to be looked at objectively, rationalised and managed appropriately so that they inflict the least possible damage to us, to those around us and particularly to the individuals whose wellbeing is our avowed quest.peer-reviewe

Orbital variations and outbursts of the unusual variable star V1129 Centauri

The variable star V1129 Cen is classified in the GCVS as being of $\beta$ Lyr type. Unusual for such stars, it exhibits outbursts roughly once a year, lasting for $\sim$40 days. For this reason, a relationship to the dwarf novae has been suspected. Here, for the first time a detailed analysis of the light curve of the system is presented. Based on observations with high time resolution obtained at the Observat\'orio do Pico dos Dias and on the long term ASAS light curve the orbital variations of the system are studied. They are dominated by ellipsoidal variations and partial eclipses of a probably slightly evolved F2 star in a binary with an orbital period of $21^{\rm h}$ $26^{\rm m}$. Comparison with the characteristics of dwarf novae show that the observational properties of V1129 Cen can be explained if it is just another dwarf novae, albeit with an unusually bright and early type mass donor which outshines the accretion disk and the mass gainer to a degree that many normal photometric and spectroscopic hallmarks of cataclysmic variables remain undetected

Nährstoffanalyse von Lupinen mittels Nah-Infra-Rot-Spektroskopie (NIRS). (BLE-Projekt 01HS043) [Analysis of nutrient components of lupine by near-infra-read-spectroscopy] Laufzeit: 11.11.2002 - 15.12.2003

Versuchsbeschreibung/Fragestellung: Aufgrund des Fütterungsverbotes von Tiermehl kommt den heimischen Körnerleguminosen in Zukunft eine wachsende Bedeutung als Eiweißergänzungsfuttermittel zu. Kenntnisse über die Nährstoffzusammensetzung und die Gehalte an wertbestimmenden Aminosäuren sind für einen gezielten Einsatz in der Rationsgestaltung unerlässlich. In der landwirtschaftlichen Praxis wird von einer Analyse der Rohnährstoffe häufig nur unzureichend Gebrauch gemacht. Die Nahinfrarotspektroskopie (NIRS) hat sich als eine zeit- und kostensparende Analysemethode bewährt und ist geeignet, die Zurückhaltung der Landwirte abzubauen. Für die Untersuchung von Lupinen mittels NIRS-Verfahrens fehlen jedoch die dafür notwendigen Kalibrierungen. Ziel des Untersuchungsvorhabens ist die Entwicklung einer Kalibrierung für die Rohnährstoffanalyse von Weißen, Gelben und Blauen Lupinen anhand des NIRS-Verfahrens. voraussichtliche Veröffentlichung der Ergebnisse: Dezember 200

Possibilities and limitations of protein supply in organic poultry and pig production. Summary of Results from EEC 2092/91 (Organic) Revision

One of the main objectives of organic agriculture is to establish a largely closed nutrient cycle within the farm system. To limit the input of nutrients in quantity and quality is relevant both to plant and livestock production. If nutrient input is unavoidable to ensure an adequate supply for the farm animals, this should preferably originate from organic systems, while the input of conventional feed stuffs should be restricted to a minimum, and synthetic products are banned. Dealing with limited availability of feed and nutrient resources is therefore a main feature of organic livestock production. The organic approach stands in contrast to the situation in conventional livestock production where the use of feeds and nutrients is restricted primarily by the purchase price. While conventional production has to face various local, regional and global problems caused by excess import and use of concentrated feeds, problems of organic livestock production are primarily related to a lack of nutrients at the farm or herd level. Due to these system-related conditions, there is concern about been able to formulate adequate rations for the nutritional-physiological needs of livestock, especially in relation to essential amino acids in the feeding of poultry and pigs. Nutritional imbalances encountered in practice might lead to deteriorating animal health and welfare. On the other hand, there is also concern that allowing conventional feedstuffs to be fed in organic livestock production. This could result in intensification of production, causing the same problems in organic as in intensive livestock production, such as animal health problems, risk of residues and GM contamination. Thus, extending the derogation for conventional feed in the EU regulation may have a damaging effect on consumer confidence in organic animal products. Work within an the EU funded research project “Organic Revision” (Research to support the revision of the EU Regulation on Organic Agriculture) has the aim to provide knowledge on how to achieve 100% organic feed rations for livestock and simultaneously avoid negative effects on the farm animals. The first step in the project is to obtain an overview of the many different and system related aspects of the protein supply in organic poultry and pig production. The nutritional-physiological effects of a variation in protein supply with respect to growth performance and protein accretion in broilers, turkeys, laying hens and pigs are examined by literature review. Furthermore, the potential effects of the supply with amino acids on product quality and animal health and welfare are addressed. Many different aspects are taken into account to discuss the question of whether extending the derogation concerning the use of non-organic feedstuffs should be considered with respect to the objectives and framework conditions of organic livestock production