OALib Journal期刊

ISSN: 2333-9721




2020 ( 8 )

2019 ( 13 )

2018 ( 22 )

2017 ( 35 )


匹配條件: “Jan Kennis” ,找到相關結果約14091條。
Survival and movement of the Congo forest mouse (Deomys ferrugineus): a comparison of primary rainforest and fallow land in Kisangani, Democratic Republic of the Congo
Jan Kennis,C. Laurent,N.D. Amundala,A.M. Dudu
African Zoology , 2012,
Abstract: The congo forest mouse, Deomys ferrugineus, occurs readily in natural and human-altered habitats in the region of Kisangani (Democratic Republic of the Congo). We studied survival and movement patterns of D. ferrugineus in both habitats. Capture-mark-recapture was used to study the effects of habitat on rodent life history both in primary rainforest and fallow land. Survival analyses taking into account trap-happiness effects were conducted using the program MARK. Abundance of D. ferrugineus was generally low within all our study grids, but it was lowest in fallow land compared to primary rainforest. Numbers of reproductively active females captured were not different between habitats but were larger during the rainy seasons. Daily movements of females, but not of males, were smaller in fallow land. Capture-mark-recapture analyses showed recapture probabilities to vary highly between grids and years. Survival probability in the primary forest was higher than in fallow land with a difference of 0.084 over a period of four weeks. This is possibly linked to the more abundant presence of the main food source (insects and termites); however other explanations are discussed in the text.
Assessment of Three Mitochondrial Genes (16S, Cytb, CO1) for Identifying Species in the Praomyini Tribe (Rodentia: Muridae)
Violaine Nicolas, Brigitte Schaeffer, Alain Didier Missoup, Jan Kennis, Marc Colyn, Christiane Denys, Caroline Tatard, Corinne Cruaud, Catherine Laredo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036586
Abstract: The Praomyini tribe is one of the most diverse and abundant groups of Old World rodents. Several species are known to be involved in crop damage and in the epidemiology of several human and cattle diseases. Due to the existence of sibling species their identification is often problematic. Thus an easy, fast and accurate species identification tool is needed for non-systematicians to correctly identify Praomyini species. In this study we compare the usefulness of three genes (16S, Cytb, CO1) for identifying species of this tribe. A total of 426 specimens representing 40 species (sampled across their geographical range) were sequenced for the three genes. Nearly all of the species included in our study are monophyletic in the neighbour joining trees. The degree of intra-specific variability tends to be lower than the divergence between species, but no barcoding gap is detected. The success rate of the statistical methods of species identification is excellent (up to 99% or 100% for statistical supervised classification methods as the k-Nearest Neighbour or Random Forest). The 16S gene is 2.5 less variable than the Cytb and CO1 genes. As a result its discriminatory power is smaller. To sum up, our results suggest that using DNA markers for identifying species in the Praomyini tribe is a largely valid approach, and that the CO1 and Cytb genes are better DNA markers than the 16S gene. Our results confirm the usefulness of statistical methods such as the Random Forest and the 1-NN methods to assign a sequence to a species, even when the number of species is relatively large. Based on our NJ trees and the distribution of all intraspecific and interspecific pairwise nucleotide distances, we highlight the presence of several potentially new species within the Praomyini tribe that should be subject to corroboration assessments.
Promoting social-emotional learning in Chinese schools: A feasibility study of PATHS implementation in Hong Kong
Chi-Ming Kam,Lance Wai-lap Wong,Kennis Mei-sze Fung
International Journal of Emotional Education , 2011,
Abstract: This paper describes a pilot study of a reduced version of the PATHS Curriculum, a Usdeveloped evidence-based SEL program, among schools in Hong Kong SAR (China). Three hundred and sixteen 12th grade students in three elementary schools participated in the study. A limited number of first grade PATHS lessons were adapted and translated into Chinese. Twelve teachers learned and adopted these lessons in their teaching. Students in these classrooms learned about different emotions and practiced self-control. The intervention lasted four months. After the intervention, students showed improvement in emotion understanding, emotion regulation and prosocial behavior. No change was observed in the level of children's problem behaviors. Over 65% of the teachers reported a high degree of satisfaction and willingness to adopt the intervention. The effects of the intervention varied among schools, with variations in the level of intervention and principal support, but not in the quality of implementation. Discussion is focused on the factors that could shape the adoption and implementation of SEL programs, especially the role of the difference in school systems between Hong Kong and the United States.
Lower frequency region mid-infrared spectroscopy by chirped pulse upconversion
Zhu Jingyi,Mathes Tilo,Stahl Andreas D.,Kennis John T.M.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134109004
Abstract: UV/visible pump, mid-IR probe spectroscopy measurements based on the chirped upconversion method were expanded to the frequency region below 1800cm 1 with the nonlinear optical crystal AgGaGeS4. Pump-probe experiments were demonstrated with GaAs and the photoreceptor protein Slr1694.
A Set of Engineered Escherichia coli Expression Strains for Selective Isotope and Reactivity Labeling of Amino Acid Side Chains and Flavin Cofactors
Jennifer Mehlhorn, Helena Steinocher, Sebastian Beck, John T. M. Kennis, Peter Hegemann, Tilo Mathes
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079006
Abstract: Biological reactions are facilitated by delicate molecular interactions between proteins, cofactors and substrates. To study and understand their dynamic interactions researchers have to take great care not to influence or distort the object of study. As a non-invasive alternative to a site-directed mutagenesis approach, selective isotope labeling in combination with vibrational spectroscopy may be employed to directly identify structural transitions in wild type proteins. Here we present a set of customized Escherichia coli expression strains, suitable for replacing both the flavin cofactor and/or selective amino acids with isotope enriched or chemically modified substrates. For flavin labeling we report optimized auxotrophic strains with significantly enhanced flavin uptake properties. Labeled protein biosynthesis using these strains was achieved in optimized cultivation procedures using high cell density fermentation. Finally, we demonstrate how this approach is used for a clear assignment of vibrational spectroscopic difference signals of apoprotein and cofactor of a flavin containing photoreceptor of the BLUF (Blue Light receptors Using FAD) family.
A Longitudinal Analysis of the Stability of Household Money Demand  [PDF]
Jan Tin
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.23046
Abstract: Past aggregate time-series studies, conducted under the assumption of a representative economic agent, frequently show that the demand for narrowly defined M1, especially non-interest-yielding demand deposit, is unstable during periods of financial innovations. Whether this is longitudinally the case among life-cycle savers is unclear. This study utilizes longitudinal data to take another look and find that volatility in the demand for non-interest-earning checking accounts in the mid and late 1990s is attributable solely to the portion held for the transactions motive. When the conventional Baumol-Tobin model is extended to include human capital and family formation variables representing the life-cycle motive, equilibrium money demand is a stable function of both economic and demographic variables.
A Spectral Method in Time for Initial-Value Problems  [PDF]
Jan Scheffel
American Journal of Computational Mathematics (AJCM) , 2012, DOI: 10.4236/ajcm.2012.23023
Abstract: A time-spectral method for solution of initial value partial differential equations is outlined. Multivariate Chebyshev series are used to represent all temporal, spatial and physical parameter domains in this generalized weighted residual method (GWRM). The approximate solutions obtained are thus analytical, finite order multivariate polynomials. The method avoids time step limitations. To determine the spectral coefficients, a system of algebraic equations is solved iteratively. A root solver, with excellent global convergence properties, has been developed. Accuracy and efficiency are controlled by the number of included Chebyshev modes and by use of temporal and spatial subdomains. As examples of advanced application, stability problems within ideal and resistive magnetohydrodynamics (MHD) are solved. To introduce the method, solutions to a stiff ordinary differential equation are demonstrated and discussed. Subsequently, the GWRM is applied to the Burger and forced wave equations. Comparisons with the explicit Lax-Wendroff and implicit Crank-Nicolson finite difference methods show that the method is accurate and efficient. Thus the method shows potential for advanced initial value problems in fluid mechanics and MHD.
Operationalizing Sustainability Principles in the Engineering Profession  [PDF]
Jan Adamowski
Natural Resources (NR) , 2012, DOI: 10.4236/nr.2012.34024
Abstract: The engineering profession has responded to the issue of sustainable development in two main ways. It has responded through public policy statements that acknowledge the magnitude of the problem in addition to pledging to steer engineering towards a more sustainable future, and it has also responded more directly through technological innovation. In this paper, these two responses will be explored with respect to the debate on how to operationalize sustainability principles in practical terms. This paper also attempts to provide the rationale for a philosophy of engineering ethics grounded in the notion of sustainable development. It is hoped that this would lead to a revised “social contract” that would enable engineers to engage more actively in political, technical, economic and social discussions and processes.
Chaos in Planar, Circular, Restricted Three-Body Problem  [PDF]
Jan Vrbik
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.41008

In this article we analyze the motion of a test particle of a planar, circular, restricted three-body problem in resonance, using the Kustaanheimo-Stiefel formalism. We show that a good qualitative description of the motion can be reduced to three simple equations for semi-major axis, eccentricity and resonance angle. Studying these equations reveals the onset of chaos, and sheds a new light on its weak nature. The 7:4 resonance is used as an example.

Compound Means and Fast Computation of Radicals  [PDF]
Jan ?ustek
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.516241
Abstract: In last decades, several algorithms were developed for fast evaluation of some elementary functions with very large arguments, for example for multiplication of million-digit integers. The present paper introduces a new fast iterative method for computing values \"\"?with high accuracy, for fixed \"\"?and \"\". The method is based on compound means and Padé approximations.

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