A model of chlorophyll a destruction by Calanus spp. and implications for the estimation of ingestion rates using the gut fluorescence method

Chlorophyll a (chl a) destruction by groups of Calanus spp. with different long-term in situ feeding histories was compared. For copepods that had fed during both pre- and early-bloom conditions, degrees of chl a destruction were relatively constant at high ingestion rates and increased as ingestion rates decreased. Assuming that 2 pools of chlorophyll bleaching enzymes (CBEs) were involved in the destruction of chl a (one derived from the copepods and one from the ingested algae), a new model was developed to describe the kinetics of chl a destruction. In this model, the CBE activity of each pool was described using a Michaelis-Menten expression and the total CBE activity was given by the sum of the 2 expressions. Parameter estimates of V(c)(max), the maximum activity of the copepod CBE, were higher for the early-bloom copepods than for the pre-bloom copepods, suggesting that the former had a higher destructive capacity. Estimates of R(p)(max), the phytoplankton 'CBE activity coefficient' which is analogous to V(max), were similar between the 2 groups of experiments. This is reasonable since most of the food fed to the copepods was healthy, actively growing diatoms. The model could also describe the kinetics of chl a destruction for Calanus spp. that had fed during late-bloom conditions. For the late-bloom data, V(c)(max) and R(p)(max) values were higher than for the pre- and early-bloom copepods and phytoplankton. This suggests that the late-bloom copepods and the in situ phytoplankton that they ate had higher destructive capacities, perhaps because the spring-bloom was more advanced. Expressions were derived from the new model to describe the relationship between real ingestion rate (I(r)) and apparent ingestion rate (I(a)), over a range of I(a) values, where the latter are values which would have been determined using gut fluorescence methodology. Correction factors (I(r)/I(a)) varied by a factor of less than 2 (for I(a) values ranging from 0.1 to 100 ng chi a ind.-1 h-1) between different groups of copepods (pre-, early- and late-bloom) and sources of algae (actively growing and senescent). In future it will be important to validate this model under controlled conditions (e.g. using single species of copepods and phytoplankton food) and to assess whether correction factors derived from our model are generally applicable, if results of studies using gut fluorescence methods are to be interpreted properly

The supercuspidal representations of p-adic classical groups

Let G be a unitary, symplectic or special orthogonal group over a locally compact non-archimedean local field of odd residual characteristic. We construct many new supercuspidal representations of G, and Bushnell-Kutzko types for these representations. Moreover, we prove that every irreducible supercuspidal representation of G arises from our constructions.Comment: 55 pages -- minor changes from 1st version (mostly in sections 2.2, 4.2 and 6.2). To appear in Inventiones mathematicae, 2008 (DOI is not yet active as at 12 Nov 2007

Risk mapping for HPAI H5N1 in Africa - Improving surveillance for virulent bird flu: Final report and maps

More than 85 percent of households in rural Africa raise poultry for food, income, or both, and many people live in close contact with their birds. The possibility of an epidemic of highly pathogenic avian influenza (HPAI) H5N1 is therefore a major concern. Since 2006 bird fl u has been introduced into at least 11 countries in Africa, and over 600 outbreaks reported. Vigilance is key to limiting the disease but animal health personnel cannot monitor everywhere at once. This risk-mapping project was designed to help prioritize their efforts by showing in which places outbreaks are more likely to occur. A risk map is a complex, computer-generated image that shows the spatial distribution of the predicted risk of a disease. It is based on the spatial distribution of “risk factors” associated with an increased risk of disease, and the relative importance of each of these factors. In the case of virulent bird fl u, risk factors include major transport routes, markets where poultry may be traded, and wetlands with the possibility of contact between poultry and wild birds. Researchers in this project have prepared risk maps for bird fl u in Africa using multi-criteria decision modeling (MCDM). In this way they have integrated data and information from such diverse sources as published scientific literature, maps available in the public domain, field surveys and expert consultations

Amélioration de la surveillance de l’influenza aviaire de type H5N1 - Cartographie du risque d’influenza aviaire de type H5N1 en Afrique: Rapport final et cartes de risqué d’influenza aviaire

Plus de 85% des ménages ruraux en Afrique élèvent la volaille aux fins d’alimentation, de revenu ou les deux, et de nombreuses personnes vivent en contact étroit avec leurs oiseaux. La possibilité d’une épidémie de l’influenza aviaire hautement pathogène (IAHP) de type H5N1 est donc une grande préoccupation. Depuis 2006, la grippe aviaire est apparue dans au moins 11 pays africains et plus de 600 foyers d’épidémie ont été signalés. La vigilance est essentielle en vue de limiter la maladie mais le personnel de santé animale ne peut faire un suivi partout à la fois. Ce projet de cartographie de facteurs de risques a été conçu en vue d’aider à prioriser leurs efforts en indiquant les lieux où il existe un risque très élevé de flambées de la maladie. La cartographie des risques est une image complexe générée par ordinateur qui montre la répartition spatiale des facteurs de risques prévus d’une maladie. Elle est fondée sur la répartition spatiale des « facteurs de risques » associés au risque accru de maladie et à l’importance relative de chacun de ces facteurs. Dans le cas d’une grippe aviaire de type H5N1, les facteurs de risques sont les principales voies de transport, les marchés de volailles et les points d’eau avec possibilité de contact entre les oiseaux domestiques et sauvages. Pour ce projet, les chercheurs ont préparé des cartes de risques de grippe aviaire en Afrique en utilisant la modélisation de décision multicritères (MCDM). De cette façon, ils ont intégré les données et les informations de diverses sources telles que les publications scientifi ques, les cartes disponibles dans le domaine public, les études de terrain et les consultations d’expert

Influence of tree species and forest land use on soil hydraulic conductivity and implications for surface runoff generation

Forest planting is increasingly being incorporated into land management policies to mitigate diffuse pollution and localised flooding because forest soils are associated with enhanced hydraulic properties and lower surface runoff compared to soils under other vegetation types. Despite this, our understanding of the effects of different tree species and forest land use on soil hydraulic properties is limited. In this study we tested for the effects of two tree species, sycamore (Acer pseudoplatanus) and Scots pine (Pinus sylvestris), subject to contrasting land use systems, namely ungrazed forest and livestock grazed forest, on soil surface saturated hydraulic conductivity (Kfs) at a long term (23 year) experimental site in Scotland. Additionally these forest land use systems were compared to grazed pasture. Kfs was found to be significantly higher under ungrazed Scots pine forest (1239 mm hr− 1) than under ungrazed sycamore forest (379 mm hr− 1) and under both of these forest types than under pasture (32 mm hr− 1). However, this measure did not differ significantly between the sycamore and Scots pine grazed forest and pasture. It was inferred, from comparison of measured Kfs values with estimated maximum rainfall intensities for various return periods at the site, that surface runoff, as infiltration excess overland flow, would be generated in pasture and grazed forest by storms with a return period of at least 1 in 2 years, but that surface runoff is extremely rare in the ungrazed forests, regardless of tree species. We concluded that, although tree species with differing characteristics can create large differences in soil hydraulic properties, the influence of land use can mask the influence of trees. The choice of tree species may therefore be less important than forest land use for mitigating the effects of surface runoff

Bibliografia

In order to determine whether small-sided game (SSG) locomotor performance can serve as a fitness indicator, we (1) compared 6-a-side (6v6) SSG-intensity of players varying in fitness and skill, (2) examined the relationship of the 6v6-SSG and Yo-Yo IR2 and (3) assessed the reliability of the 6v6-SSG. Thirty-three professional senior, 30 professional youth, 62 amateur and 16 professional woman football players performed 4 × 7 min 6v6-SSGs recorded by a Local Position Measurement system. A substantial subgroup (N = 113) also performed the Yo-Yo IR2. Forty-seven amateur players performed two or three 6v6-SSGs. No differences in 6v6-SSG time-motion variables were found between professional senior and professional youth players. Amateurs showed lower values than professional seniors on almost all time-motion variables (ES = 0.59‒1.19). Women displayed lower high-intensity time-motion variables than all other subgroups. Total distance run during 6v6-SSG was only moderately related to Yo-Yo IR2 distance (r = 0.45), but estimated metabolic power, high speed (>14.4 km ·