OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Helman” ,找到相关结果约41条。
A Gradient Search Algorithm for the Maximal Visible Area Polygon Problem  [PDF]
Helman I. Stern, Moshe Zofi
American Journal of Operations Research (AJOR) , 2015, DOI: 10.4236/ajor.2015.53013
Abstract: This paper provides a gradient search algorithm for finding the maximal visible area polygon (VAP) viewed by an interior point in a simple polygon P. The algorithm is based on a natural partition of P into convex sets, such that each element of the partition is associated with a unique analytical form of the area function. We call this partition a back diagonal partition of P. Our maximal VAP algorithm converges in a finite number of steps, and is polynomial with a complexity of \"\" , for a simple polygon P with n vertices, and r reflex vertices. We use the maximal VAP algorithm as a basis for a greedy heuristic for the well known guardhouse problem with a computation complexity of \"\" .
Solving the Multi Observer 3D Visual Area Coverage Scheduling Problem by Decomposition  [PDF]
Helman I. Stern, Moshe Zofi, Moshe Kaspi
American Journal of Operations Research (AJOR) , 2011, DOI: 10.4236/ajor.2011.13014
Abstract: This paper presents two solution methodologies for the Visual Area Coverage Scheduling problem. The objective is to schedule a number of dynamic observers over a given 3D terrain such that the total visual area covered (viewed) over a planning horizon is maximal. This problem is a more complicated extension of the Set Covering Problem, known to be Np-Hard. We present two decomposition based heuristic methods each containing three stages. The first methodology finds a set of area covering points, and then partitions them into routes (cover first, partition second). The second methodology partitions the area into a region for each observer, and then finds the best covering points and routes (partition first, cover second). In each, a last stage determines dwell (view) times so as to maximize the visible coverage smoothly over the terrain. Comparative tests were made for the two methods on real terrains for several scenarios. When comparing the best solutions of both methods the CF-PS method was slightly better. However, because of the increased computation time we suggest that the PF-CS method with a fine terrain approximation be used. This method is faster as partitioning the terrain into separate regions for each observer results in smaller coverage and routing problems. A sensitivity analysis of the number of observation points to the total number of terrain points covered depicted the classical notion of decreasing returns to scale, increasing in a convex manner as the number of observation points was increased. The best method achieved 100 percent coverage of the terrain by using only 2.7 percent of its points as observation points. Experts stated that the computer based solutions can save precious time and help plan observation missions with satisfying results.
Doen a versus Enfermidade na Clínica Geral
Cecil G. Helman
Campos - Revista de Antropologia Social , 2009,
Learning Optimal Augmented Bayes Networks
Vikas Hamine,Paul Helman
Computer Science , 2005,
Abstract: Naive Bayes is a simple Bayesian classifier with strong independence assumptions among the attributes. This classifier, desipte its strong independence assumptions, often performs well in practice. It is believed that relaxing the independence assumptions of a naive Bayes classifier may improve the classification accuracy of the resulting structure. While finding an optimal unconstrained Bayesian Network (for most any reasonable scoring measure) is an NP-hard problem, it is possible to learn in polynomial time optimal networks obeying various structural restrictions. Several authors have examined the possibilities of adding augmenting arcs between attributes of a Naive Bayes classifier. Friedman, Geiger and Goldszmidt define the TAN structure in which the augmenting arcs form a tree on the attributes, and present a polynomial time algorithm that learns an optimal TAN with respect to MDL score. Keogh and Pazzani define Augmented Bayes Networks in which the augmenting arcs form a forest on the attributes (a collection of trees, hence a relaxation of the stuctural restriction of TAN), and present heuristic search methods for learning good, though not optimal, augmenting arc sets. The authors, however, evaluate the learned structure only in terms of observed misclassification error and not against a scoring metric, such as MDL. In this paper, we present a simple, polynomial time greedy algorithm for learning an optimal Augmented Bayes Network with respect to MDL score.
Paleoenvironmental Implications from Biomarker Investigations on the Pliocene Lower Sajau Lignite Seam in Kasai Area, Berau Basin, Northeast Kalimantan, Indonesia  [PDF]
Khalda Az Zahra, Ahmad Helman Hamdani, R. Tina Rosmalina
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.35016

Pliocene age lignites from Lower Sajau seam, from borehole in Berau Basin, Northeast Kalimantan, Indonesia were investigated with respect to organic geochemistry by HPLC, GC and GC/MS. The analysis was conducted to drilling sequence of Kasai Coal Field, Berau Basin which has been applied to identify organic sources and maturity of organic matter. The result of normalized yields of the soluble organic matter (SOM) data indicates saturated and aromatic proportion of hydrocarbon are very low (under 10%), this was reflecting that lignite coal is still in immature stage. Moreover, biomarker hydrocarbon such as diterpenoids was not found from the sample that indicates absence of gymnosperm precursor in the paleo-peat. In contrast, there was great abundance of terpenoid biomarkers including lupane and oleanane showing domination of angiosperms indicate that angiosperm was dominated vegetation source. There also hopanoid biomarkers explaining acidic depositional environment in coal formation and microbes-affected conditions in peat formation process. Ratio of Tm/Ts shows paleomire where ratios value of Tm/Ts is in range of oxide condition.

Estrategia y Política de Transporte Internacional
Eugenio Helman,Sergio Albano,Bruno Cignacco
Economic Analysis Working Papers , 2006,
Abstract: Ante la existencia de relieves con vías hidrográficas de importancia se presenta como más eficiente el transporte acuático en comparación a las demás alternativas, pudiéndose utilizar en ríos de suficiente caudal el sistema mediante barcazas. El sistema de barcazas hace necesaria la coparticipación publica- privada, evaluándose a tal efecto los impactos económicos y medioambientales. Por otra parte, se resalta la importancia de los barcos “ro-ro” que agilizan la operatoria portuaria, logrando descensos de costos y una eficiente combinación de medios. Todas estas vías de transportación deben estar articuladas dentro de un sistema integrador que considere las potencialidades regionales teniendo en cuenta los centros geoestratégicos más relevantes y las conexiones bioceánicas de la región. A modo ejemplificativo se exponen las principales características del Río Bermejo, con sus principales canales básicos y su impacto socioeconómico. La invención de la esclusa permitió la unión a grandes niveles, a punto tal que la descarga a través de una turbina puede ser aprovechada para nivelar esclusas. El aprovechamiento nacional e internacional: Ríos como los de Alemania, a partir del Rhin y el complejo sistema de afluentes, los canales holandeses, la interconexión de los ríos Loire, Sena, Garma, Saona, Ródano y Rhin. En consecuencia, se esta avanzando en la estandarización de la construcción de barcazas. Ejemplo: Bélgica. Hoy en Rosario existe un proyecto para la construcción de barcazas. Comparación desde el punto de vista económico de distintas formas de transporte: Costos Por cada HP transportado Buque 1 Camión 150 Km. Barcaza 2 Ferrocarril 500 Km. Ferrocarril 7 Barcaza 4000 Km. Camión 32
Low Dose Histone Deacetylase Inhibitor, Depsipeptide (FR901228), Promotes Adenoviral Transduction in Human Rhabdomyosarcoma Cell Lines
Fariba Navid,Blaine T. Mischen,Lee J. Helman
Sarcoma , 2004, DOI: 10.1080/13577140410001679220
Abstract: Purpose. Transduction of rhabdomyosarcoma (RMS) cells with adenoviral vectors for in vivo and in vitro applications has been limited by the low to absent levels of coxackie and adenovirus receptor (CAR). This study investigates the potential use of low doses of a histone deacetylase inhibitor, depsipeptide (FR901228), currently in Phase II human trials, to enhance adenoviral uptake in six rhabdomyosarcoma cell lines.
Depression, Antidepressant Use and Mortality in Later Life: The Health in Men Study
Osvaldo P. Almeida,Helman Alfonso,Graeme J. Hankey,Leon Flicker
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011266
Abstract: Depression is associated with increased mortality, but it is unclear if this relationship is dose-dependent and if it can be modified by treatment with antidepressants.
Which women stop smoking during pregnancy and the effect on breastfeeding duration
Roslyn C Giglia, Colin W Binns, Helman S Alfonso
BMC Public Health , 2006, DOI: 10.1186/1471-2458-6-195
Abstract: A 12 month longitudinal study was conducted in two public maternity hospitals in Perth, Australia between mid-September 2002 and mid-July 2003. While in hospital, participating mothers completed a self-administered baseline questionnaire. Follow up telephone interviews were conducted at 4, 10, 16, 22, 32, 40 and 52 weeks.A total of 587 (55%) mothers participated in the study. Two hundred and twenty six (39%) mothers reported smoking prior to pregnancy and 77 (34%) of these stopped smoking during pregnancy. Women who were pregnant for the first time were twice as likely (OR = 2.05; 95% CI 1.047 – 4.03; p < 0.05) to quit smoking as multiparous women. Women who smoked more than 10 cigarettes per day were significantly less likely to quit smoking during pregnancy (OR = 0.36; 95% CI 0.18 – 0.69; p < 0.05). Women who consumed alcohol before pregnancy were three times more likely to quit smoking (OR = 2.58; 95% CI 1.00 – 6.66; p < 0.05). Quitting smoking during pregnancy was significantly associated with breastfeeding for longer than six months (OR = 3.70; 95% CI 1.55 – 8.83; p < 0.05).Pregnancy is a time when many women are motivated to quit smoking and providing targeted smoking cessation interventions at this time, which take into account factors predictive of quitting smoking, are more likely to be successful.Despite considerable public understanding of the dangers of smoking during pregnancy, prevalence levels in Australia range between approximately 17%, reported in 2001, and 35%, reported in 1996 [1,2].Substantial public health gains remain to be made in perinatal mortality and morbidity through the reduction of smoking during pregnancy [3] and pregnancy appears to be a time when women are highly motivated to quit smoking in the best interests of their unborn foetus. However, despite this not all women choose to quit smoking at this time and the differences between women who do stop smoking during pregnancy and those who don't may be caused by factors that can be in
Discordant antibody and cellular responses to Pneumocystis major surface glycoprotein variants in mice
Lisa R Bishop, Daniel Helman, Joseph A Kovacs
BMC Immunology , 2012, DOI: 10.1186/1471-2172-13-39
Abstract: Proliferative responses to each of two recombinant Msg variant proteins were seen in mice immunized with either recombinant protein, but no proliferation to these antigens was seen in mice immunized with crude Pneumocystis antigens or in mice that had cleared infection, although the latter animals demonstrated proliferative responses to crude Pneumocystis antigens and native Msg. IL-17 and MCP-3 were produced in previously infected animals in response to the same antigens, but not to recombinant antigens. Antibody responses to the recombinant P. murina Msg variant proteins were seen in all groups of animals, demonstrating that all groups were exposed to and mounted immune responses to Msg. No human PBMC samples proliferated following stimulation with P. jirovecii Msg, while antibody responses were detected in sera from 4 of 5 samples.Cross-reactive antibody responses to Msg variants are common, while cross-reactive T cell responses are uncommon; these results support the hypothesis that Pneumocystis utilizes switching of Msg variant expression to avoid host T cell responses.

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