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Search Results: 1 - 10 of 189884 matches for " Hand G "
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Ethical Issues in Physiatrist Practice
Hand G
Indian Journal of Physical Medicine and Rehabilitation , 2008,
Abstract: Editorial on Ethical Issues. Medical ethics is at the centre of medical practice. It isrightly gaining much needed renewed focus and attentionin the evolving scenario. The impetus for it may beattributed to the revelations that arose through Nurembergtrials, the framework elements that define research andpublications related compulsions, and indeed the contextand state of affairs of present day medical jurisprudence.The physiatrist’s practice cannot remain untouched bythe moral and ethical dilemmas faced in today’s world.Although the pillars of the specialty are grounded in the
Estimates of the Fast and Termal Flux in Blanket of Critical Reactors by Using Multi-Group Methods  [PDF]
Aybaba Han?erlio?ullari, Asl? Kurnaz, Yosef G. Ali Madee, Ltfei A. Abdalsmd, Salem A. A. Shufat, Khaled M. Elhadad, Hand Hadia Almezogi, Mansur Mohamed Ali Mansur
Open Journal of Applied Sciences (OJAppS) , 2017, DOI: 10.4236/ojapps.2017.72007
Abstract: In this study, based differential equations methods are used to solve equations because these methods are dependent on boundary value data more than other mathematical equations. We have calculated neutron flux, criticality and geometrical eigenvalue by using multi-group method and solving the neutron diffusion equation for finite and infinite cylindrical and spherical reactors in this study. For the calculation of the total neutron flux cross sections, we need the neutron diffusion equation. Thus, we have established the relationship between neuron flow and cross-section of neuron depending on neutron energy. Critical calculations have been made by comparing the results with MNCP (montecarlo n-partical) simulation methods. For necessary computer calculations, the programme, Wolfram-Matematica-7 has been used.
A picture or a 1000 words?
The Turkish Online Journal of Distance Education , 2000,
Conditions for Existence of Dual Certificates in Rank-One Semidefinite Problems
Paul Hand
Mathematics , 2013, DOI: 10.4310/CMS.2014.v12.n7.a11
Abstract: Several signal recovery tasks can be relaxed into semidefinite programs with rank-one minimizers. A common technique for proving these programs succeed is to construct a dual certificate. Unfortunately, dual certificates may not exist under some formulations of semidefinite programs. In order to put problems into a form where dual certificate arguments are possible, it is important to develop conditions under which the certificates exist. In this paper, we provide an example where dual certificates do not exist. We then present a completeness condition under which they are guaranteed to exist. For programs that do not satisfy the completeness condition, we present a completion process which produces an equivalent program that does satisfy the condition. The important message of this paper is that dual certificates may not exist for semidefinite programs that involve orthogonal measurements with respect to positive-semidefinite matrices. Such measurements can interact with the positive-semidefinite constraint in a way that implies additional linear measurements. If these additional measurements are not included in the problem formulation, then dual certificates may fail to exist. As an illustration, we present a semidefinite relaxation for the task of finding the sparsest element in a subspace. One formulation of this program does not admit dual certificates. The completion process produces an equivalent formulation which does admit dual certificates.
PhaseLift is robust to a constant fraction of arbitrary errors
Paul Hand
Mathematics , 2015,
Abstract: Consider the task of recovering an unknown $n$-vector from phaseless linear measurements. This task is the phase retrieval problem. Through the technique of lifting, this nonconvex problem may be convexified into a semidefinite rank-one matrix recovery problem, known as PhaseLift. Under a linear number of exact Gaussian measurements, PhaseLift recovers the unknown vector exactly with high probability. Under noisy measurements, the solution to a variant of PhaseLift has error proportional to the $\ell_1$ norm of the noise. In the present paper, we study the robustness of this variant of PhaseLift to a case with noise and gross, arbitrary corruptions. We prove that PhaseLift can tolerate a small, fixed fraction of gross errors, even in the highly underdetermined regime where there are only $O(n)$ measurements. The lifted phase retrieval problem can be viewed as a rank-one robust Principal Component Analysis (PCA) problem under generic rank-one measurements. From this perspective, the proposed convex program is simpler that the semidefinite version of the sparse-plus-low-rank formulation standard in the robust PCA literature. Specifically, the rank penalization through a trace term is unnecessary, and the resulting optimization program has no parameters that need to be chosen. The present work also achieves the information theoretically optimal scaling of $O(n)$ measurements without the additional logarithmic factors that appear in existing general robust PCA results.
A Markov Random Field Topic Space Model for Document Retrieval
Scott Hand
Computer Science , 2011,
Abstract: This paper proposes a novel statistical approach to intelligent document retrieval. It seeks to offer a more structured and extensible mathematical approach to the term generalization done in the popular Latent Semantic Analysis (LSA) approach to document indexing. A Markov Random Field (MRF) is presented that captures relationships between terms and documents as probabilistic dependence assumptions between random variables. From there, it uses the MRF-Gibbs equivalence to derive joint probabilities as well as local probabilities for document variables. A parameter learning method is proposed that utilizes rank reduction with singular value decomposition in a matter similar to LSA to reduce dimensionality of document-term relationships to that of a latent topic space. Experimental results confirm the ability of this approach to effectively and efficiently retrieve documents from substantial data sets.
A Mesoproterozoic continental flood rhyolite province, the Gawler Ranges, Australia: the end member example of the Large Igneous Province clan
M. J. Pankhurst, B. F. Schaefer, P. G. Betts, N. Phillips,M. Hand
Solid Earth (SE) & Discussions (SED) , 2011, DOI: 10.5194/se-2-25-2011
Abstract: Rhyolite and dacite lavas of the Mesoproterozoic upper Gawler Range Volcanics (GRV) (>30 000 km3 preserved), South Australia, represent the remnants of one of the most voluminous felsic magmatic events preserved on Earth. Geophysical interpretation suggests eruption from a central cluster of feeder vents which supplied large-scale lobate flows >100 km in length. Pigeonite inversion thermometers indicate eruption temperatures of 950–1100 °C. The lavas are A-type in composition (e.g. high Ga/Al ratios) and characterised by elevated primary halogen concentrations (~1600 ppm fluorine, ~400 ppm chlorine). These depolymerised the magma such that temperature-composition-volatile non-Arrhenian melt viscosity modelling suggests they had viscosities of <3.5 log η (Pa s). These physicochemical properties have led to the emplacement of a Large Rhyolite Province, which has affinities in emplacement style to Large Basaltic Provinces. The low viscosity of these felsic magmas has produced a unique igneous system on a scale which is either not present or poorly preserved elsewhere on the planet. The Gawler Range Volcanic Province represents the erupted portion of the felsic end member of the family of voluminous, rapidly emplaced terrestrial magmatic provinces.
Measured and modeled humidification factors of fresh smoke particles from biomass burning: role of inorganic constituents
J. L. Hand,D. E. Day,G. M. McMeeking,E. J. T. Levin
Atmospheric Chemistry and Physics Discussions , 2010,
Abstract: During the 2006 FLAME study (Fire Laboratory at Missoula Experiment), laboratory burns of biomass fuels were performed to investigate the physico-chemical, optical, and hygroscopic properties of fresh biomass smoke. As part of the experiment, two nephelometers simultaneously measured dry and humidified light scattering coefficients (bsp(dry) and bsp(RH), respectively) in order to explore the role of relative humidity (RH) on the optical properties of biomass smoke aerosols. Results from burns of several biomass fuels showed large variability in the humidification factor (f(RH)=bsp(RH)/bsp(dry)). Values of f(RH) at RH=85–90% ranged from 1.02 to 2.15 depending on fuel type. We incorporated measured chemical composition and size distribution data to model the smoke hygroscopic growth to investigate the role of inorganic and organic compounds on water uptake for these aerosols. By assuming only inorganic constituents were hygroscopic, we were able to model the water uptake within experimental uncertainty, suggesting that inorganic species were responsible for most of the hygroscopic growth. In addition, humidification factors at 85–90% RH increased for smoke with increasing inorganic salt to carbon ratios. Particle morphology as observed from scanning electron microscopy revealed that samples of hygroscopic particles contained soot chains either internally or externally mixed with inorganic potassium salts, while samples of weak to non-hygroscopic particles were dominated by soot and organic constituents. This study provides further understanding of the compounds responsible for water uptake by young biomass smoke, and is important for accurately assessing the role of smoke in climate change studies and visibility regulatory efforts.
Neurogenin2 regulates the initial axon guidance of cortical pyramidal neurons projecting medially to the corpus callosum
Randal Hand, Franck Polleux
Neural Development , 2011, DOI: 10.1186/1749-8104-6-30
Abstract: The genetic loss of Ngn2 in mice results in fewer callosal axons projecting towards the midline as well as abnormal midline crossing. shRNA-mediated knockdown of Ngn2 revealed its cell-autonomous requirement for the proper projection of axons from layer 2/3 pyramidal neurons to the midline in vivo. We found that the acute loss of Ngn2 in vivo induces the axon of superficial layer 2/3 neurons to project laterally towards aberrant cortical and subcortical targets.These and previous results demonstrate that Ngn2 is required for the coordinated specification of cardinal features defining the phenotype of cortical pyramidal neurons, including their migration properties, dendritic morphology and axonal projection.The mammalian nervous system consists of a tremendous diversity of neuronal subtypes forming complex functional circuits. In the cerebral cortex, long-distance-projecting glutamatergic pyramidal neurons arise from radial glial progenitors located in the dorsal telencephalon [1]. During cortical neurogenesis in rodents, radial glial progenitors divide asymmetrically to generate another radial glial progenitor and an intermediate progenitor cell (IPC) that translocates to the subventricular zone (SVZ) [1]. These IPCs display a transient multipolar morphology characterized by the dynamic extension and retraction of immature neurites, which might sense their micro-environment and respond to cues polarizing their leading process (future apical dendrite) dorsally towards the cortical plate and their trailing process (future axon) ventrally [2,3]. During this polarization, the neuron adheres to a radial glial cell process and initiates radial migration through the cell-sparse but axon-rich intermediate zone (IZ) towards the pial surface. Upon reaching the top of the cortical plate, just below the pial surface, pyramidal neurons detach from the radial glial cell and undergo terminal translocation before elaborating both their dendritic and axonal processes. In mice, neur
The Discourse of Argumentation
Brian Hand,Emily Schoerning
Mevlana International Journal of Education , 2012,
Abstract: This study seeks to characterize the discourse of classrooms that utilize the Science Writing Heuristic (SWH), an approach to Argument Based Inquiry (ABI). Linguistic behaviors that lend themselves to inclusion in a discourse that supports argumentation are examined, such as frequency of dialog interchange and instances of student-student speech. Students and teachers in SWH classrooms utilize linguistic behaviors that support argumentation significantly more frequently than their counterparts in classrooms that utilize more traditional pedagogies. The linguistic behaviors characterized in this study allow us to more clearly describe the discourse that develops under the SWH approach. This discourse is specifically illuminated as a discourse of argumentation, in which the importance of student voice is a key underlying value.
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