Seabird metapopulations: searching for alternative breeding habitats

Today, many seabird species nest in port areas, which are also necessary for human economic activity. In this paper, we evaluate, using a metapopulation model, the possibilities for creating alternative breeding sites for the Common Tern (Sterna hirundo) in the Rhine¿Meuse¿Scheldt estuary. We explore 22 scenarios that differ with respect to (1) loss of breeding habitat in port areas, (2) location and size of newly created habitat, and (3) coexistence of old and new habitat. Results indicate that loss of port area habitats results in a serious 41% decline in the breeding population. When the loss in ports is compensated for within the ports, the decline was negligible. Fourteen scenarios result in an increase of the Common Tern metapopulation. In these, extra breeding habitat is created outside the ports in fish-rich waters, resulting in a potential metapopulation increase of 25%. However, the period of overlap between lost and newly created habitat strongly affects the results. A gap between the removal of old and the creation of new breeding areas might cause a drop in the metapopulation level of 30%. The population recovery from this drop might take more than 100 years due to slow recolonization. Our results suggest that conservation of seabird species should be evaluated on a metapopulation scale and that the creation of new habitat may help to compensate for habitat loss in other areas. Furthermore, the results indicate that overlap between the existence of old and newly created breeding habitats is crucial for the success of compensation efforts. However, new locations should be carefully selected, because not only is the suitability of the breeding grounds important, but ample fish availability nearby is also ke

Energy management of people in organizations

Abstract Although energy is a concept that is implied in many motivational theories, is hardly ever explicitly mentioned or researched. The current article first relates theories and research findings that were thus far not explicitly related to energy. We describe theories such as flow, subjective well-being, engagement and burn-out, and make the link with energy more explicit. Also, we make a first link between personality characteristics and energy, and describe the role of leadership in unleashing followers’ energy. Following, we identify how the topic of energy management can be profitably incorporated in research from a scientific as well as a practitioner viewpoint. Finally, we describe several interventions to enhance energy in individuals and organizations

African indigenous vegetables: An overview of the cultivated species

Until the beginning of the 20th century, people in Africa depended to a significant extent on food which had its origins in Africa. A diverse range of originally wild African species was domesticated a long time ago and included rootcrops, cereals, legumes and many different vegetables. Popular food crops from outside the region were introduced into Africa and these exotic crops soon started to dominate the traditional crops. This trend was enforced with the arrival of European settlers and has resulted in most African vegetables becoming minor crops. However, most exotic crops are not successful in either dry or very humid regions and do not do well in the warmer parts of Africa; in these regions indigenous African crops are still important and indigenous vegetables are much in demand because many people no longer have enough money to buy the more expensive exotic crops. Consequently there is now a reversal in the trend away from exotics and towards traditional vegetables. This has generated a call for information, especially from students who wish to focus on such crops, and from extension staff who are under pressure from farmers to advise them. African Indigenous Vegetables, an Overview of the Cultivated Species describes over 100 African vegetable species and covers the 25 most common crops in detail. Where possible, information is provided on the origin of the species and on some botanical aspects. The main emphasis is on their agronomy, providing as much detail as is currently known about these crops. It is to be hoped that this book will contribute towards knowledge of African vegetables and their further advancement

Acrylamide: Increased concentrations in homemade food and first evidence of its variable absorption from food, variable metabolism and placental and breast milk transfer in humans

We have developed a liquid chromatography/mass spectrometry (LC-MS/MS) assay to determine acrylamide in various body fluids. The assay also allows the reliable quantitation of acrylamide in food. In a total of 11 healthy male and female subjects, we were able to show that acrylamide from food given to humans is in fact absorbed from the gut. The half-lives determined in two male subjects were 2.2 and 7 h. Acrylamide was found in human breast milk and penetrated the human placenta (n = 3). The variability of acrylamide concentrations found in this investigation is most likely caused by variable intersubject bioavailability and metabolism. This may be an important indication that the assessment of the risk from acrylamide for the individual may be very difficult without knowing the concentrations of acrylamide in the body. This should be considered in the design of any risk assessment study or post hoc analysis of earlier studies. At this time, we suggest that pregnant women and breast-feeding mothers avoid acrylamide-containing food. Copyright (C) 2002 S. Karger AG, Basel

Photoionization of tungsten ions: experiment and theory for W4+^{4+}

Experimental and theoretical results are reported for single-photon single ionization of the tungsten ion W$^{4+}$. Absolute cross sections have been measured employing the photon-ion merged-beams setup at the Advanced Light Source in Berkeley. Detailed photon-energy scans were performed at 200~meV bandwidth in the 40 -- 105~eV range. Theoretical results have been obtained from a Dirac-Coulomb R-matrix approach employing basis sets of 730 levels for the photoionization of W$^{4+}$. Calculations were carried out for the $4f^{14}5s^2 5p^6 5d^2 \; {^3}{\rm F}_{J}$, $J$=2, ground level and the associated fine-structure levels with $J$=3 and 4 for the W$^{4+}$ ions. In addition, cross sections have been calculated for the metastable levels $4f^{14}5s^2 5p^6 5d^2 \; {^3}{\rm P}_{0,1,2},{^1}{\rm D}_{2},{^1}{\rm G}_{4},{^1}{\rm S}_{0}$. Very satisfying agreement of theory and experiment is found for the photoionization cross section of W$^{4+}$ which is remarkable given the complexity of the electronic structure of tungsten ions in low charge states.Comment: 15 pages, 3 figures, to appear in the Journal of Physics B: Atomic, Molecular and Optical Physic

Impact of fungicide applications for late blight management on huckleberry yields in Cameroon

The influence of late blight infections, caused by Phytophthora infestans, was evaluated on thirteen huckleberry (Solanum scabrum) varieties during the 2000 and 2001 cropping seasons in Dschang, Cameroon. A randomised split block design was used. Plants were sprayed four times with Ridomil Plus® (12% metalaxyl + 60% cuprous oxide) at 2.5 kg ha-1 on a 21-day schedule while control plots were not sprayed. Late blight intensity was recorded weekly and fresh shoot yields were evaluated six times at 14-day intervals. Fungicide applications significantly reduced late blight intensity and consequently increased huckleberry yields. Cumulative shoot yields varied with the variety and fungicide treatment, from 54.14 to 238.33 t ha-1. Yield losses due to late blight infection were estimated at up to 46%. Economic analyses indicated that fungicide sprays are necessary for a late blight protection programme in huckleberry. This spray regime based on fungicide application resulted in net profits of US$694 to$ 8,467 ha-1, depending on the variety used and the trial period. The results show that late blight infections if not controlled, decrease huckleberry yields, and consequently net farm incomes. High yielding resistant varieties or foliar applications of Ridomil Plus® may be incorporated in integrated pathogen management schemes against late blight in huckleberries with a view to minimise use of fungicides. Key Words: Integrated management, Phytophthora infestans, Solanum scabrum, yield loss Résumé L'influence du mildiou, causé par Phytophthora infestans, était évalué sur treize variétés de la morelle noire (Solanum scabrum) pendant les saisons culturalles de l'an 2000 et 2001 à Dschang, Cameroun. Les éssais étaient réalisés en split-blocs pris au hazard. Les plantes étaient traitées quatre fois avec Ridomil Plus (12% de métalaxyl + 60% oxyde cuivreux) à 21 jours d'intervalle à la dose de 2.5 kg ha-1. L'intensité du mildiou a été évalué hebdomadairement et les pousses fraiches ont été récoltées six fois à l'intervalle de 14 jours. Des traitements fongicides ont significativement réduit l'intensité du mildiou et par conséquent augmenté le rendement en pousses. Le rendement total en pousses fraiches a été variable. De 54, 14 à 238,33 t ha-1, selon la variété et le traitement fongicide. Des pertes en rendements associées aux attaques du mildiou ont atteint 46%. Des analyses économiques indiquent que quatre traitements au Ridomil plus"sont nécessaires dans un bon programme de protection de la morelle noire contre le mildiou. Ce régime de traitement a poduit des augmentations en revenu net de USS 694 à 8.467 ha-1, selon la variété utilisée et la période d'essai. Des résultats indiquent que le mildiou peut baisser le rendement de la morelle noire et par conséquent le bénéfice net des planteurs de la morelle noire si les actions appropriées ne sont pas menées pour rayer les effets néfastes de cette maladie. En outre, l'utilisation des variétés résistantes ou des traitements foliaires au Ridomil plus" peut etre incorporée dans des programmes de lutte intégrée contre le mildiou de la morelle noire. Mots Clés: Gestion intégrée, Phytophthora infestans, Solanum scabrum, perte de rendement (Af Crop Sci J 2003 Vol 11 No 3 pp163-170