Optimization of self-similar factor approximants

The problem is analyzed of extrapolating power series, derived for an asymptotically small variable, to the region of finite values of this variable. The consideration is based on the self-similar approximation theory. A new method is suggested for defining the odd self-similar factor approximants by employing an optimization procedure. The method is illustrated by several examples having the mathematical structure typical of the problems in statistical and chemical physics. It is shown that the suggested method provides a good accuracy even when the number of terms in the perturbative power series is small.Comment: Latex file, 16 page

Modification of the National Weather Service Distributed Hydrologic Model for subsurface water exchanges between grids

To account for spatial variability of precipitation, as well as basin physiographic properties, the National Weather Service (NWS) has developed a distributed version of its hydrologic component, termed the Hydrology Laboratory-Research Distributed Hydrologic Model (HL-RDHM). Because channels are the only source of water exchange between neighboring computational elements, the absence of such exchange has been identified as a weakness in the model. The primary objective of this paper is to modify the model structure to account for subsurface water exchanges without dramatically altering the conceptual framework of the water balance module. The subsurface exchanges are established by partitioning the slow response components released from the lower layer storages into two parts: the first part involves the grid's conceptual channel, while the second is added to the lower layer storages of the downstream pixel. Realizing the deficiency of the water balance module to locate the lower zone layers in sufficient depths, a complementary study is conducted to test the feasibility of further improvement in the modified model by equally shifting downward the lower zone layers of all pixels over the basin. The Baron Fork at Eldon, Oklahoma, is chosen as the test basin. Ten years of grid-based multisensor precipitation data are used to investigate the effects of the modification, plus shifting the lower zone layers on model performance. The results show that the modified-shifted HL-RDHM can markedly improve the streamflow simulations at the interior point, as well as very high peak-flow simulations at the basin's outlet. Copyright 2011 by the American Geophysical Union

Observation of a red-blue detuning asymmetry in matter-wave superradiance

We report the first experimental observations of strong suppression of matter-wave superradiance using blue-detuned pump light and demonstrate a pump-laser detuning asymmetry in the collective atomic recoil motion. In contrast to all previous theoretical frameworks, which predict that the process should be symmetric with respect to the sign of the pump-laser detuning, we find that for condensates the symmetry is broken. With high condensate densities and red-detuned light, the familiar distinctive multi-order, matter-wave scattering pattern is clearly visible, whereas with blue-detuned light superradiance is strongly suppressed. In the limit of a dilute atomic gas, however, symmetry is restored.Comment: Accepted by Phys. Rev. Let

Assessment of RNAi-induced silencing in banana (Musa spp.)

In plants, RNA- based gene silencing mediated by small RNAs functions at the transcriptional or post-transcriptional level to negatively regulate target genes, repetitive sequences, viral RNAs and/or transposon elements. Post-transcriptional gene silencing (PTGS) or the RNA interference (RNAi) approach has been achieved in a wide range of plant species for inhibiting the expression of target genes by generating double-stranded RNA (dsRNA). However, to our knowledge, successful RNAi-application to knock-down endogenous genes has not been reported in the important staple food crop banana

Singularities of equidistants and global centre symmetry sets of Lagrangian submanifolds

We define the Global Centre Symmetry set (GCS) of a smooth closed m-dimensional submanifold M of R^n, $n \leq 2m$, which is an affinely invariant generalization of the centre of a k-sphere in R^{k+1}. The GCS includes both the centre symmetry set defined by Janeczko and the Wigner caustic defined by Berry. We develop a new method for studying generic singularities of the GCS which is suited to the case when M is lagrangian in R^{2m} with canonical symplectic form. The definition of the GCS, which slightly generalizes one by Giblin and Zakalyukin, is based on the notion of affine equidistants, so, we first study singularities of affine equidistants of Lagrangian submanifolds, classifying all the stable ones. Then, we classify the affine-Lagrangian stable singularities of the GCS of Lagrangian submanifolds and show that, already for smooth closed convex curves in R^2, many singularities of the GCS which are affine stable are not affine-Lagrangian stable.Comment: 26 pages, 2 figure

Etude de la dynamique des populations d’ongulés sauvages par une appréciation de la qualité de leurs trophées dans les Parcs Nationaux de la Pendjari et du W au Bénin

Depuis la réouverture de la chasse sportive au Bénin, des mensurations de trophées d’animaux ont été réalisées de 1999-2004. Les mensurations faites sur des spécimens provenant d’une dizaine d’ongulés sauvages ont fait l’objet d’analyses permettant une appréciation de la qualité des animaux, en termes de classes d’âge. Sur les dix espèces, seulement trois, à savoir le Buffle, le Phacochère et le Cobe defassa ont présenté des trophées très remarquables, les prélèvements n’ayant été opérés que sur de vieux mâles. Les subadultes sont surtout enregistrés chez le Bubale, les Cobes de Buffon et Redunca, le Céphalophe, le Guib et l’Ourébi, ce qui est indicateur d’une raréfaction de mâles adultes. L’étude corrobore aussi l’hypothèse d’une perturbation de la structure des âges des populations de Cobes defassa notamment, car ce sont de vieux mâles qui sont prélevés, créant un écrêtement de la pyramide des âges. La cause de cet écrêtement est donc la chasse sportive bien conduite, qui permet d’éliminer les vieux mâles, de rajeunir et de multiplier les harems. Les mensurations de trophées de gibiers abattus dans les zones cynégétiques des parcs nationaux constituent donc un procédé avéré pour approcher l’étude de la dynamique des populations de faune

A case study of government innovative programmes for increasing access to qualified health personnel in selected rural districts of Zambia

Objective: To document the experiences and lessons learnt from implementing innovative programmes that aim at increasing access to qualified health workers in Gwembe and Chibombo districts by Ministry of Health and participation of health workers.Methods: Qualitative analysis of the participation and satisfaction rates in retention and recruitment incentives for health workers in Gwembe and Chibombo Districts was conducted. Further document review of the current strategies implemented by the government was conducted with regards to them addressing the problems identified by the health workers based on a criterion that was developed. The study used primary and secondary data.Results: The findings indicated that there was high desire by the health workers to leave their current rural job postings and this was mainly due to issues related to their living and working conditions rather than the participation or satisfaction in the existing retention andrecruitment schemes. There was substantial turnover in the health workforces in both districts over the five-year period from 2005-2009, with annual losses ranging from 2 percent to 16 percent of the professional health workforce in each district. These losses were dues to death, retirement and redirection. Overall, there was also very little evidence and the quality of much of what existed was weak hence the difficult to ascertain if these interventions were contributing to an increase in access to qualified health workers in rural areas.Conclusion: To retain staff in the rural areas remains a challenge because of the high desire to leave exhibited by health workers. Bundled interventions therefore coupled with strong national leadership, governance and information systemsare key in ensuring skilled, motivated and supported health workers at the right place and time. In addition, a strong monitoring and evaluation system should be establised to provide evidence and lessons to ascertain which interventions are or are not working and inform further policy decisions on health workforce

On polynomially integrable domains in Euclidean spaces

Let $D$ be a bounded domain in $\mathbb R^n,$ with smooth boundary. Denote $V_D(\omega,t), \ \omega \in S^{n-1}, t \in \mathbb R,$ the Radon transform of the characteristic function $\chi_{D}$ of the domain $D,$ i.e., the $(n-1)-$ dimensional volume of the intersection $D$ with the hyperplane $\{x \in \mathbb R^n: =t \}.$ If the domain $D$ is an ellipsoid, then the function $V_D$ is algebraic and if, in addition, the dimension $n$ is odd, then $V(\omega,t)$ is a polynomial with respect to $t.$ Whether odd-dimensional ellipsoids are the only bounded smooth domains with such a property? The article is devoted to partial verification and discussion of this question

Nonholonomic systems with symmetry allowing a conformally symplectic reduction

Non-holonomic mechanical systems can be described by a degenerate almost-Poisson structure (dropping the Jacobi identity) in the constrained space. If enough symmetries transversal to the constraints are present, the system reduces to a nondegenerate almost-Poisson structure on a ``compressed'' space. Here we show, in the simplest non-holonomic systems, that in favorable circumnstances the compressed system is conformally symplectic, although the ``non-compressed'' constrained system never admits a Jacobi structure (in the sense of Marle et al.).Comment: 8 pages. A slight edition of the version to appear in Proceedings of HAMSYS 200

40 years of veterinary papers in JAC – what have we learnt?

This review, for the occasion of the 40th anniversary of the Journal of Antimicrobial Chemotherapy (JAC), gives an overview of the manuscripts related to veterinary bacteriology published in the journal in the past 40 years with a focus on ‘One Health’ aspects. From 1975 to 2000 the number of manuscripts related to veterinary medicine was limited, but thereafter, the number steadily increased. Most manuscripts published were related to food-producing animals, but companion animals and minor species were also covered. Subjects included antimicrobial usage in animals and the consequences for human medicine, new resistance genes and mechanisms, the prevalence and epidemiology of antimicrobial resistance, and the emergence of resistant bacteria in animals with zoonotic potential such as livestock-associated MRSA (LA-MRSA), methicillin-resistant Staphylococcus pseudintermedius (MRSP) and ESBL-producing Enterobacteriaceae. These manuscripts have added to our knowledge on the risks of transmission of resistant bacteria from animals to humans and the importance of the prudent use of antimicrobial agents in veterinary medicine