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Search Results: 1 - 10 of 11795 matches for " Charles Huber "
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East African pholcid spiders: an overview, with descriptions of eight new species (Araneae, Pholcidae)
Bernhard A. Huber,Charles M. Warui
European Journal of Taxonomy , 2012, DOI: 10.5852/ejt.2012.29
Abstract: This paper summarizes current knowledge about East African pholcids. East Africa is defined as the area from 12°S to 5°N and from 28° to 42°E, including all of Uganda, Kenya, Burundi, Rwanda, and Tanzania. An annotated list of the 15 genera and 87 species recorded from this area is given, together with distribution maps and an identification key to genera. Most East African species (90%) belong to one of only six genera: Buitinga Huber, 2003 (21 species); Smeringopus Simon, 1890 (18); Pholcus Walckenaer, 1805 (17); Spermophora Hentz, 1841 (12); Leptopholcus Simon, 1893 (5) and Quamtana Huber, 2003 (4). Eight species for which DNA sequence data have been published recently are newly described: Buitinga batwa sp. nov., B. wataita sp. nov., Spermophora mau sp. nov., S. maathaiae sp. nov., S. bukusu sp. nov., S. kirinyaga sp. nov., S. kyambura sp. nov. and Quamtana nyahururu sp. nov. Crossopriza johncloudsleyi Deeleman-Reinhold & van Harten, 2001, previously only known from Yemen, is redescribed based on specimens from Kenya. Additional new records are given for 21 previously described species.
Kinematics of the swimming of Spiroplasma
Jing Yang,Charles W. Wolgemuth,Greg Huber
Physics , 2009, DOI: 10.1103/PhysRevLett.102.218102
Abstract: \emph{Spiroplasma} swimming is studied with a simple model based on resistive-force theory. Specifically, we consider a bacterium shaped in the form of a helix that propagates traveling-wave distortions which flip the handedness of the helical cell body. We treat cell length, pitch angle, kink velocity, and distance between kinks as parameters and calculate the swimming velocity that arises due to the distortions. We find that, for a fixed pitch angle, scaling collapses the swimming velocity (and the swimming efficiency) to a universal curve that depends only on the ratio of the distance between kinks to the cell length. Simultaneously optimizing the swimming efficiency with respect to inter-kink length and pitch angle, we find that the optimal pitch angle is 35.5$^\circ$ and the optimal inter-kink length ratio is 0.338, values in good agreement with experimental observations.
Representing Partitions on Trees
Katharina T. Huber,Vincent Moulton,Charles Semple,Taoyang Wu
Quantitative Biology , 2014,
Abstract: In evolutionary biology, biologists often face the problem of constructing a phylogenetic tree on a set $X$ of species from a multiset $\Pi$ of partitions corresponding to various attributes of these species. One approach that is used to solve this problem is to try instead to associate a tree (or even a network) to the multiset $\Sigma_{\Pi}$ consisting of all those bipartitions $\{A,X-A\}$ with $A$ a part of some partition in $\Pi$. The rational behind this approach is that a phylogenetic tree with leaf set $X$ can be uniquely represented by the set of bipartitions of $X$ induced by its edges. Motivated by these considerations, given a multiset $\Sigma$ of bipartitions corresponding to a phylogenetic tree on $X$, in this paper we introduce and study the set $P(\Sigma)$ consisting of those multisets of partitions $\Pi$ of $X$ with $\Sigma_{\Pi}=\Sigma$. More specifically, we characterize when $P(\Sigma)$ is non-empty, and also identify some partitions in $P(\Sigma)$ that are of maximum and minimum size. We also show that it is NP-complete to decide when $P(\Sigma)$ is non-empty in case $\Sigma$ is an arbitrary multiset of bipartitions of $X$. Ultimately, we hope that by gaining a better understanding of the mapping that takes an arbitrary partition system $\Pi$ to the multiset $\Sigma_{\Pi}$, we will obtain new insights into the use of median networks and, more generally, split-networks to visualize sets of partitions.
Using direct observations on multiple occasions to measure household food availability among low-income Mexicano residents in Texas colonias
Joseph R Sharkey, Wesley R Dean, Julie A St John, J Charles Huber
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-445
Abstract: Because most studies use a single point of data collection to determine the types of foods that are present in the home, which can miss the change in availability within a month and when resources are not available, the primary objective of this pilot study was to examine the feasibility and value of conducting weekly in-home assessments of household food resources over the course of one month among low-income Mexicano families in Texas colonias.We conducted five in-home household food inventories over a thirty-day period in a small convenience sample; determined the frequency that food items were present in the participating households; and compared a one-time measurement with multiple measurements.After the development and pre-testing of the 252-item culturally and linguistically- appropriate household food inventory instrument that used direct observation to determine the presence and amount of food and beverage items in the home (refrigerator, freezer, pantry, elsewhere), two trained promotoras recruited a convenience sample of 6 households; administered a baseline questionnaire (personal info, shopping habits, and food security); conducted 5 in-home assessments (7-day interval) over a 30-day period; and documented grocery shopping and other food-related activities within the previous week of each in-home assessment. All data were collected in Spanish. Descriptive statistics were calculated for mean and frequency of sample characteristics, food-related activities, food security, and the presence of individual food items. Due to the small sample size of the pilot data, the Friedman Test and Kendall's W were used to assess the consistency of household food supplies across multiple observations.Complete data were collected from all 6 Mexicano women (33.2y ± 3.3; 6.5 ± 1.5 adults/children in household (HH); 5 HH received weekly income; and all were food insecure. All households purchased groceries within a week of at least four of the five assessments. The weekly pr
Activation/Inhibition of mast cells by supra-optimal antigen concentrations
Michael Huber
Cell Communication and Signaling , 2013, DOI: 10.1186/1478-811x-11-7
Vegetacion y flora de Pantepui, Region Guayana
Huber, Otto;
Acta Botanica Brasilica , 1987, DOI: 10.1590/S0102-33061987000300005
Abstract: the biogeographical province pantepui, which is herewith defined as the entirety of orographic ecosystems developed in the table mountains ("tepuis") of the guayana shield region above 1.200/1.500 m a.s.1., presents a varied and highly evolved vegetation composed of a specialized flora of some 2.000 - 2.500 species. it harbours two endemic families, the saccifoliaceae and the tepuianthaceae, the latter with a somewhat wider extension into the guayana lowlands. the most important families from the systematic as well ecologic point of view are the asteraceae, rubiaceae, theaceae, ochnaceae, rapateaceae, eriocaulaceae, xyridaceae, bromeliaceae, and cyperaceae. the plant cover consists of a great number of different vegetation types, belonging essentially to four plant formations: the arboreal (low tepui forests), the scrub formation (tepui scrub, paramoid scrub), the herbaceous (tepui meadows), and the pioneer formation on open rocks (lithophytic vegetation). other than the consistent stock of endemic, autochthonous taxa, the phytogeographical relationships of the pantepui flora are with the high andrean flora, the guayanan and amazonian lowland flora, the general neotropical flora, and the pantropical or cosmopolitan flora
Explicit solutions of the Rand Equation
A Huber
International Journal of Engineering, Science and Technology , 2010,
Abstract: In this paper the meaning of a nonlinear partial differential equation (nPDE) of the third-order is shown to the first time. The equation is known as the ‘Rand Equation’ and belongs to a class of less studied nPDEs. Both the explicit physical meaning as well as the behaviour is not known until now. Therefore we believe it is indispensable to study this evolution equation in detail. We perform a classical Lie Group analysis to analyze the point symmetries. By using a similarity reduction we are able to deduce more classes of solutions of general character. Special nonlinear transformations are given in a most general form. In addition, we also study Lie’s non-classical case relating to potential and generalized symmetries. Both the potential and approximate symmetries are discussed to the first time leading to new results. So we expect a better understanding and concrete physical as well as technical application in future.
The physical meaning of a nonlinear evolution equation of the fourth order relating to locally and non-locally supercritical waves
A Huber
International Journal of Engineering, Science and Technology , 2010,
Abstract: In this paper the physical meaning of a nonlinear partial differential equation (nPDE) of the fourth order relating to wave theory is deduced to the first time. The equation under consideration belongs to a class of less studied nPDEs and an explicit physical meaning is not known until now. This paper however bridges the gap between some known results and a concrete application concerning wave theory. We show how one can derive locally supercritical solitary waves as well as locally and nonlocally forced supercritical waves and analytical solutions are given explicitly.
Imaging the brain: visualising “pathological entities”? Searching for reliable protocols within psychiatry and their impact on the understanding of psychiatric diseases
Lara Huber
Poiesis & Praxis , 2009, DOI: 10.1007/s10202-008-0055-1
Abstract: Face à l’augmentation nette des visualisations qui se base sur l’imagerie médicale ces derniers décennies, la présence des coupes du cerveau codé en couleur qui ont générées sur des applications fonctionelles a contribué à la supposition de pouvoir extrapoler si un individu est affecté par un syndrome neurologique, neuropsychologique ou psychiatrique des profils cognitives (“kinds” of brains). Dans le contexte clinique, il est notamment indispensable de remarquer que des visualisations qui se base sur l’imagerie médicale sont suggestive à plus d’un point de vue. Les enregistrements de l’imagerie médicale ne seulement visualisent des entités pathologiques, mais aussi représentent les états psychophysiques d’une manière objective et concrète. D’une vue epistemologique, cet article débat des aspects clé des visualisations qui se base sur des applications fonctionelles des neurosciences.
On an improved method for solving evolution equations of higher order importantly in science and technology
A Huber
International Journal of Engineering, Science and Technology , 2010,
Abstract: In this paper we introduce a new algebraic procedure to compute new classes of solutions of (1+1)-nonlinear partial differential equations (nPDEs) both of physical and technical relevance. The basic assumption is that the unknown solution(s) of the nPDE under consideration satisfy an ordinary differential equation (ODE) of the first order that can be integrated completely. This solution manifold of these first-order ODEs play an essential part in solving given nPDEs. A further important aspect however is the fact that we have the freedom in choosing some parameters bearing positively on the algorithm and hence, the solution-manifold of any nPDEs under consideration are therefore augmented naturally. The present algebraic procedure can widely use to study many nPDE and is not only restricted to time-dependent problems. We note that no numerical methods are necessary and so analytical closed-form classes of solutions result. The algorithm works accurately, is clear structured and can be converted in any computer language. On the contrary it is worth to stress the necessity of such sophisticated methods since a general theory of nPDEs does not exist.
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