1,386 research outputs found
Variational methods for fractional -Sturm--Liouville Problems
In this paper, we formulate a regular -fractional Sturm--Liouville problem
(qFSLP) which includes the left-sided Riemann--Liouville and the right-sided
Caputo -fractional derivatives of the same order , . We introduce the essential -fractional variational analysis needed
in proving the existence of a countable set of real eigenvalues and associated
orthogonal eigenfunctions for the regular qFSLP when associated
with the boundary condition . A criteria for the first eigenvalue
is proved. Examples are included. These results are a generalization of the
integer regular -Sturm--Liouville problem introduced by Annaby and Mansour
in [1]
Characteristics of Vehicular Traffic Flow at a Roundabout
We construct a stochastic cellular automata model for the description of
vehicular traffic at a roundabout designed at the intersection of two
perpendicular streets. The vehicular traffic is controlled by a self-organized
scheme in which traffic lights are absent. This controlling method incorporates
a yield-at-entry strategy for the approaching vehicles to the circulating
traffic flow in the roundabout. Vehicular dynamics is simulated within the
framework of the probabilistic cellular automata and the delay experienced by
the traffic at each individual street is evaluated for specified time
intervals. We discuss the impact of the geometrical properties of the
roundabout on the total delay. We compare our results with traffic-light
signalisation schemes, and obtain the critical traffic volume over which the
intersection is optimally controlled through traffic light signalisation
schemes.Comment: 10 pages, 17 eps figures. arXiv admin note: text overlap with
arXiv:cond-mat/040107
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Diversity Maximization Under Matroid Constraints
Aggregator websites typically present documents in the form of representative clusters. In order for users to get a broader perspective,it is important to deliver a diversified set of representative documents in those clusters. One approach to diversification is to maximize the average dissimilarity among documents. Another way to capture diversity is to avoid showing several documents from the same category (e.g. from the same news channel). We model the latter approach as a (partition) matroid constraint, and study diversity maximization problems under matroid constraints. We present the first constant-factor approximation algorithm for this problem,using a new technique. Our local search 0:5-approximation algorithm is also the first constant-factor approximation for the maxdispersion problem under matroid constraints. Our combinatorial proof technique for maximizing diversity under matroid constraints uses the existence of a family of Latin squares which may also be of independent interest. In order to apply these diversity maximization algorithms in the context of aggregator websites and as a preprocessing step for our diversity maximization tool, we develop greedy clustering algorithms that maximize weighted coverage of a predefined set of topics. Our algorithms are based on computing a set of cluster centers, where clusters are formed around them. We show the better performance of our algorithms for diversity and coverage maximization by running experiments on real (Twitter) and synthetic data in the context of real-time search over micro-posts. Finally we perform a user study validating our algorithms and diversity metrics
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Fosmanogepix (APX001) Is Effective in the Treatment of Immunocompromised Mice Infected with Invasive Pulmonary Scedosporiosis or Disseminated Fusariosis.
There are limited treatment options for immunosuppressed patients with lethal invasive fungal infections due to Fusarium and Scedosporium Manogepix (MGX; APX001A) is a novel antifungal that targets the conserved Gwt1 enzyme required for localization of glycosylphosphatidylinositol-anchored mannoproteins in fungi. We evaluated the in vitro activity of MGX and the efficacy of the prodrug fosmanogepix (APX001) in immunosuppressed murine models of hematogenously disseminated fusariosis and pulmonary scedosporiosis. The MGX minimum effective concentration (MEC) for Scedosporium isolates was 0.03 μg/ml and ranged from 0.015 to 0.03 μg/ml for Fusarium isolates. In the scedosporiosis model, treatment of mice with 78 mg/kg and 104 mg/kg of body weight fosmanogepix, along with 1-aminobenzotriazole (ABT) to enhance the serum half-life of MGX, significantly increased median survival time versus placebo from 7 days to 13 and 11 days, respectively. Furthermore, administration of 104 mg/kg fosmanogepix resulted in an ∼2-log10 reduction in lung, kidney, or brain conidial equivalents/gram tissue (CE). Similarly, in the fusariosis model, 78 mg/kg and 104 mg/kg fosmanogepix plus ABT enhanced median survival time from 7 days to 12 and 10 days, respectively. A 2- to 3-log10 reduction in kidney and brain CE was observed. In both models, reduction in tissue fungal burden was corroborated with histopathological data, with target organs showing reduced or no abscesses in fosmanogepix-treated mice. Survival and tissue clearance were comparable to a clinically relevant high dose of liposomal amphotericin B (10 to 15 mg/kg). Our data support the continued development of fosmanogepix as a first-in-class treatment for infections caused by these rare molds
The hidden curriculum of a special education program in a Junior Science College in Malaysia
The purpose of this study was to explore the facets of the hidden curriculum in a Junior Science College from the perspective of students labelled as gifted. This college is set up specifically for gifted and high academic achiever students. A qualitative approach was chosen to gather the data from former students and current teachers of this college. The data was collected from three focus group interviews with 16 former students, individual interviews with four students and 6 teachers, observations of school activities and document reviews. The data was analysed manually, codes and categories were identified and a rich description based on the categories was written to answer the research question. The results showed that the hidden curriculum is the result of the practices, procedures, rules, relationships, structures and physical characteristics of the Special Education Program (SEP). Eight themes were identified which resulted in the learning of intrapersonal and interpersonal skills. The study concluded that the hidden curriculum facilitated the transmission of social norms while the learning improved positive interpersonal and intrapersonal skills in the students, in spite of the restrictive nature of the special education program. According to the results, it can be concluded that flexibility and creativity in instruction promotes positive traits in students and teachers
Diffusive transport of light in two-dimensional granular materials
We study photon diffusion in a two-dimensional random packing of monodisperse
disks as a simple model of granular material. We apply ray optics approximation
to set up a persistent random walk for the photons. We employ Fresnel's
intensity reflectance with its rich dependence on the incidence angle and
polarization state of the light. We present an analytic expression for the
transport-mean-free path in terms of the refractive indices of grains and host
medium, grain radius, and packing fraction. We perform numerical simulations to
examine our analytical result.Comment: 9 pages, 3 figure
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