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Search Results: 1 - 10 of 122771 matches for " Jason T. Isaacs "
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Dubins Traveling Salesman Problem with Neighborhoods: A Graph-Based Approach
Jason T. Isaacs,Jo?o P. Hespanha
Algorithms , 2013, DOI: 10.3390/a6010084
Abstract: We study the problem of finding the minimum-length curvature constrained closed path through a set of regions in the plane. This problem is referred to as the Dubins Traveling Salesperson Problem with Neighborhoods (DTSPN). An algorithm is presented that uses sampling to cast this infinite dimensional combinatorial optimization problem as a Generalized Traveling Salesperson Problem (GTSP) with intersecting node sets. The GTSP is then converted to an Asymmetric Traveling Salesperson Problem (ATSP) through a series of graph transformations, thus allowing the use of existing approximation algorithms. This algorithm is shown to perform no worse than the best existing DTSPN algorithm and is shown to perform significantly better when the regions overlap. We report on the application of this algorithm to route an Unmanned Aerial Vehicle (UAV) equipped with a radio to collect data from sparsely deployed ground sensors in a field demonstration of autonomous detection, localization, and verification of multiple acoustic events.
Loss of Androgen Receptor-Dependent Growth Suppression by Prostate Cancer Cells Can Occur Independently from Acquiring Oncogenic Addiction to Androgen Receptor Signaling
Jason M. D'Antonio,Donald J. Vander Griend,Lizamma Antony,George Ndikuyeze,Susan L. Dalrymple,Shahriar Koochekpour,John T. Isaacs
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011475
Abstract: The conversion of androgen receptor (AR) signaling as a mechanism of growth suppression of normal prostate epithelial cells to that of growth stimulation in prostate cancer cells is often associated with AR mutation, amplification and over-expression. Thus, down-regulation of AR signaling is commonly therapeutic for prostate cancer. The E006AA cell line was established from a hormone na?ve, localized prostate cancer. E006AA cells are genetically aneuploid and grow equally well when xenografted into either intact or castrated male NOG but not nude mice. These cells exhibit: 1) X chromosome duplication and AR gene amplification, although paradoxically not coupled with increased AR expression, and 2) somatic, dominant-negative Serine-599-Glycine loss-of-function mutation within the dimerization surface of the DNA binding domain of the AR gene. No effect on the growth of E006AA cells is observed using targeted knockdown of endogenous mutant AR, ectopic expression of wild-type AR, or treatment with androgens or anti-androgens. E006AA cells represent a prototype for a newly identified subtype of prostate cancer cells that exhibit a dominant-negative AR loss-of-function in a hormonally na?ve patient. Such loss-of-function eliminates AR-mediated growth suppression normally induced by normal physiological levels of androgens, thus producing a selective growth advantage for these malignant cells in hormonally na?ve patients. These data highlight that loss of AR-mediated growth suppression is an independent process, and that, without additional changes, is insufficient for acquiring oncogene addiction to AR signaling. Thus, patients with prostate cancer cells harboring such AR loss-of-function mutations will not benefit from aggressive hormone or anti-AR therapies even though they express AR protein.
Strengthening research in community medicine
Isaacs Anton
Indian Journal of Community Medicine , 2007,
Measuring Inter Epidemic Risk in a Dengue Endemic Rural Area Using Aedes larval Indices
Isaacs N
Indian Journal of Community Medicine , 2006,
Endoscopic retrograde cholangiopancreatography training in the United Kingdom: A critical review
Peter Isaacs
World Journal of Gastrointestinal Endoscopy , 2011,
Abstract: Endoscopic retrograde cholangiopancreatography training used to be in virtually all district general hospitals, resulting in a large number of trainees with an inadequate case load and achieving poor levels of skill. Training is now restricted to a small number of trainees working in approved units. Continuous audit of outcomes and the appointment of a training lead in the unit are essential. Use of the global rating scale helps clinicians advise hospital administration on the priorities for a quality training program.
The Land and Nightfall…
Bruce Isaacs.
Nebula , 2005,
Abstract: A Poem.
Macaques as model hosts for studies of HIV-1 infection
Jason T. Kimata*
Frontiers in Microbiology , 2013, DOI: 10.3389/fmicb.2013.00176
Abstract: Increasing evidence indicates that the host range of primate lentiviruses is in part determined by their ability to counteract innate restriction factors that are effectors of the type 1 interferon (IFN-1) response. For human immunodeficiency virus type 1 (HIV-1), in vitro experiments have shown that its tropism may be narrow and limited to humans and chimpanzees because its replication in other non-human primate species is hindered by factors such as TRIM5α (tripartite motif 5 alpha), APOBEC3G (apolipoprotein B mRNA-editing, enzyme-catalytic, polypeptide-like 3), and tetherin. Based on these data, it has been hypothesized that primate lentiviruses will infect and replicate in a new species if they are able to counteract and evade suppression by the IFN-1 response. Several studies have tested whether engineering HIV-1 recombinants with minimal amounts of simian immunodeficiency virus sequences would enable replication in CD4+ T cells of non-natural hosts such as Asian macaques and proposed that infection of these macaque species could be used to study transmission and pathogenesis. Indeed, infection of macaques with these viruses revealed that Vif-mediated counteraction of APOBEC3G function is central to cross-species tropism but that other IFN-induced factors may also play important roles in controlling replication. Further studies of these macaque models of infection with HIV-1 derivatives could provide valuable insights into the interaction of lentiviruses and the innate immune response and how lentiviruses adapt and cause disease.
A Survey of Multiple Planet Systems
Jason T. Wright
Physics , 2009, DOI: 10.1051/eas/1042001
Abstract: As of August 2008, over 30 multiple exoplanet systems are known, and 28% of stars with planets show significant evidence of a second companion. I briefly review these 30 systems individually, broadly grouping them into five categories: 1) systems with 3 or more giant (Msini > 0.2 M_Jup) planets, 2) systems with two giant planets in mean motion resonance (MMR), 3) systems with two giant planets not in MMR but whose dynamical evolution is affected by planet-planet interactions, 4) highly hierarchical systems, having two giant planets with very large period ratios (> 30:1), and 5) systems of ``Super-Earths'', containing only planets with (Msini < 20 M_Earth). It now appears that eccentricities are not markedly higher among planets in known multiple planet systems, and that planets with Msini < 1 M_Jup have lower eccentricities than more massive planets. The distribution of semimajor axes for planets in multiplanet systems does not show the 3-day pile-up or the 1 AU "jump" of the apparently-single planet distribution.
Shadow Theory, data model design for data integration
Jason T. Liu
Computer Science , 2012,
Abstract: For data integration in information ecosystems, semantic heterogeneity is a known difficulty. In this paper, we propose Shadow Theory as the philosophical foundation to address this issue. It is based on the notion of shadows in Plato's Allegory of the Cave. What we can observe are just shadows, and meanings of shadows are mental entities that only exist in viewers' cognitive structures. With enterprise customer data integration example, we proposed six design principles and algebra to support required operations.
Methodology for Comparing Coupling Algorithms for Fluid-Structure Interaction Problems  [PDF]
Jason P. Sheldon, Scott T. Miller, Jonathan S. Pitt
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.42007

The multi-physics simulation of coupled fluid-structure interaction problems, with disjoint fluid and solid domains, requires one to choose a method for enforcing the fluid-structure coupling at the interface between solid and fluid. While it is common knowledge that the choice of coupling technique can be very problem dependent, there exists no satisfactory coupling comparison methodology that allows for conclusions to be drawn with respect to the comparison of computational cost and solution accuracy for a given scenario. In this work, we develop a computational framework where all aspects of the computation can be held constant, save for the method in which the coupled nature of the fluid-structure equations is enforced. To enable a fair comparison of coupling methods, all simulations presented in this work are implemented within a single numerical framework within the deal.ii [1] finite element library. We have chosen the two-dimensional benchmark test problem of Turek and Hron [2] as an example to examine the relative accuracy of the coupling methods studied; however, the comparison technique is equally applicable to more complex problems. We show that for the specific case considered herein the monolithic approach outperforms partitioned and quasi-direct methods; however, this result is problem dependent and we discuss computational and modeling aspects which may affect other comparison studies.

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