127,387 research outputs found
Dual Hierarchy for Gravitational n-body
No full textThe n-body problem is the simulation of pair-wise interactions between n objects. This problem appears in many forms, with the classic example being the modeling of gravitational forces between point masses, necessary for cosmological simulations. Many approximation approaches have been devised to reduce the complexity of this problem.t-SNE is a data visualization method that requires repeatedly solving a variant of the n-body problem. A recent paper (An Efficient Dual-Hierarchy t-SNE Minimization, van de Ruit et. al.) proposes a novel algorithm that outperforms other t-SNE minimization methods on medium-scale datasets. The report proves the viability of a dual-traversal method that uses an embedding tree to emit forces and an independent field tree to collect forces. Because the embedding tree is a Linear-BVH and the field tree is an orthtree built to a fixed depth, the overall algorithm has linear complexity.This thesis demonstrates how the dual-tree approach can be adapted for gravitational n-body simulations. Following this, it measures the performance against similar implementations of other algorithms and shows that while the adapted Dual Hierarchy approach is faster than Barnes-Hut, it is outperformed by the Fast Multipole Method on realistic large-scale cosmological datasets.https://github.com/JacksonCampolattaro/n-body Git repository containing an implementation of the adapted Dual Hierarchy algorithm for Gravitational n-body, as well as implementations of several other common algorithms compared against during benchmarking.Computer Engineerin
Anton Grabner-Haider, Johann Maier, Kulturgeschichte des frühen Christentums. Von 100 bis 500 n. Chr., Göttingen, Vandenhoeck & Ruprecht, 2008
No full textMatter Michel. Anton Grabner-Haider, Johann Maier, Kulturgeschichte des frühen Christentums. Von 100 bis 500 n. Chr., Göttingen, Vandenhoeck & Ruprecht, 2008. In: Revue d'histoire et de philosophie religieuses, 89e année n°3, Juillet-Septembre 2009. pp. 434-435
A note on mapping class group actions on derived categories
No full textLet Xnbe a cycle of n projective lines and Tn a symplectic torus with n punctures. Using the theory of spherical twists introduced by Seidel and Thomas, the author will define an action of the pure mapping class group of Tn on Db(Coh(Xn)). The motivation comes from homological mirror symmetry for degenerate elliptic curves, which was studied by the author with Treumann and Zaslow
Reactions of n,n-dibromobenzenesulfonamide with alcohols and mercaptans, 1971
No full textN,N-Dibromobenzenesulfonamide reacts with primary alcohols in a 1:2 molar ratio to yield the esters of the alcohols. The reaction is believed to proceed via a free radical mechanism to generate the reac-tive acylbromide species which then reacts with another mole of the alcohol to yield the ester as the final product. Benzyl alcohol and short chain primary alcohols give the corresponding aldehydes as side reactions. NNDBS reacts with secondary alcohols to give ketones and alpha bromoketones. No reaction takes place with tertiary alcohols. N,N-Dibromobenzenesulfonamide reacts with primary, secondary and tertiary mercaptans to yield the disulfide of the mercaptans in each case. When molecular bromine was used as the brominating agent, the alcohols did not react but the corresponding disulfide was obtained from each mercaptan
Experimental investigation into the effect of substrate clamping on the piezoelectric behaviour of thick-film PZT elements
No full textThis paper details an experimental investigation of the clamping effect associated with thick-film piezoelectric elements printed on a substrate. The clamping effect reduces the measured piezoelectric coefficient, d33, of the film. This reduction is due to the influence of the d31 component in the film when a deformation of the structure occurs, by either the direct or indirect piezoelectric effect. Theoretical analysis shows a reduction in the measured d33 of 62%, i.e. a standard bulk lead zirconate titanate (PZT)-5H sample with a manufacturer specified d33 of 593pC/N would fall to 227.8pC/N. To confirm this effect, the d33 coefficients of five thin bulk PZT-5H samples of 220µm thickness were measured before and after their attachment to a metallized 96% alumina substrate. The experimental results show a reduction in d33 of 74% from 529pC/N to 139pC/N. The theoretical analysis was then applied to existing University of Southampton thick-film devices. It is estimated that the measured d33 value of 131pC/N of the thick-film devices is the equivalent of an unconstrained d33 of 345pC/N
On ternary monoid of hypersubstitutions of type ? = (n)
No full textA ternary monoid of hypersubstitutions of type ? = (n) is the set Hyp(n) of all hypersubstitutions of type ? = (n) with a ternary operation which satis es the associative law, and has the identity element ?id . For n = 2 , the idempotent and regular elements, the ideals of submonoids and some algebraic-properties of this monoid were studied by author. In this present paper, we study the algebraic-structural properties of Hyp(n), n > 2 and characterize the idempotent and regular elements. In particular, we describe the relationships between some submonoids of this monoid under the ideal of this submonoids
After seven years in Key West, Florida, author John N. Cole learned to appreciat
No full textAfter seven years in Key West, Florida, author John N. Cole learned to appreciate Maine winters for their beauty and power
Hypergolic ignition by head-on collision of N,N,N',N'-tetramethylethylenediamine and white fuming nitric acid droplets
No full text
Hypergolic ignition by the head-on collision of a smaller N,N,N',N' tetramethylethylenediamine (TMEDA) droplet and a larger white fuming nitric acid (WFNA) droplet was experimentally investigated by using a droplet collision experimental apparatus equipped with a time-resolved shadowgraph, a photodetector and an infrared detector. The investigation was focused on understanding the influence of droplet collision and mixing, which vary with the collisional Weber number (We = 20-220) and the droplet size ratio (Delta = 1.2-2.9) while have a fixed Ohnesorge number (Oh = 2.5x10(-3)), on the hypergolic ignitability and the ignition delay times. The hypergolic ignition was found to critically rely on the heat release from of the liquid-phase reaction of TMEDA and nitric acid, which is subsequent to and enhanced by the effective mixing of the droplets of proper size ratios. Consequently, the ignitability regime nomogram in the We-A space shows that the hypergolic ignition favors small Delta s and large Wes; the ignition delay times tend to decrease with either decreasing Delta, or increasing We, or both. A non-monotonic variation of the ignition delay times with We was observed and attributed to the non-monotonic emergence of jet-like mixing patterns that enhance the droplet mixing and hence the liquid-phase reaction. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.</p
Getting Started as a Medical Teacher in Times of Change
No full textMedical school teaching is a skill that is very often learned on the job. The faculty comprised of researchers and clinicians are expert in many biomedical disciplines, but familiarity with learning theories and pedagogy are usually not included in their knowledge and skill sets. The pressure to see patients and acquire extramural funding leaves little time for faculty to learn how to teach. When coupled with the natural attrition of senior faculty it is necessary to start junior faculty on the correct path to being effective medical educators who are capable of lecturing and facilitating. Institutions cannot afford to have medical educators learn through trial and error. The standards set by the Liaison Committee on Medical Education (LCME) are also creating an urgency to produce competent teachers as quickly as possible. Novice teachers need to be able to use these standards to align their teaching with goals, objectives and the appropriate pedagogy. This article is designed to be a self-directed guide describing some essentials that a newly hired faculty member can quickly use to get started. An institutional faculty development program can then serve to build upon and enrich the experience for the new faculty member.This is the authors' accepted manuscript of the article. The final publication is available at Springer via http://dx.doi.org/doi:10.1007/s40670-014-0098-y.Peer reviewe
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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