1,933 research outputs found
Organic structure determination using 2-D NMR spectroscopy : a problem-based approach / Jeffrey H. Simpson.
No full textpharmacy bookfair2015Includes bibliographical references and index.xvi, 574 pages :"The second edition of this book comes with a number of new figures, passages, and problems. Increasing the number of figures from 290 to 448 has necessarily added considerable length, weight, and, expense. It is my hope that the book has not lost any of its readability and accessibility. I firmly believe that most of the concepts needed to learn organic structure determination using nuclear magnetic resonance spectroscopy do not require an extensive mathematical background. It is my hope that the manner in which the material contained in this book is presented both reflects and validates this belief"-- Provided by publisher
Erratum: The GALAH survey: Chemical homogeneity of the Orion complex (Monthly Notices of the Royal Astronomical Society (2021) 506 ((4232-4250) DOI: 10.1093/mnras/stab1767)
No full textThis is an erratum to the paper 'The GALAH survey: Chemical homogeneity of the Orion complex' (2021, MNRAS, 506, 4232-4250). In the originally published version of this manuscript, there was a typographical error in the name of author Jeffrey D. Simpson; the name was given as Jefferey D. Simpson. This has now been corrected. This paper has been typeset from a Microsoft Word file prepared by the author.Peer-reviewe
sj-docx-1-tae-10.1177_20420188221083512 – Supplemental material for Testosterone concentrations and prescription patterns of 1% testosterone gel in transgender and gender diverse individuals
No full textSupplemental material, sj-docx-1-tae-10.1177_20420188221083512 for Testosterone concentrations and prescription patterns of 1% testosterone gel in transgender and gender diverse individuals by Brendan J. Nolan, Sav Zwickl, Alex F. Q. Wong, Peter Locke, Satu Simpson, Ling Li, Jeffrey D. Zajac and Ada S. Cheung in Therapeutic Advances in Endocrinology and Metabolism</p
Photoalignment Layers for Liquid Crystals from the Di-π-methane Rearrangement
No full textPhotoalignment of nematic liquid crystals is demonstrated using a di-π-methane rearrangement of a designed polymer. The alignment mechanism makes use of the strong coupling of the liquid crystal directors to dibenzobarrelene groups. The large structural changes that accompany photoisomerization effectively passivate segments of the polymer, allowing the remaining dibenzobarrelene groups to dominate the director alignment. Photoisomerization requires triplet sensitization, and the polymer was designed to have a uniaxially fixed rigid structure and rapid triplet energy transfer from the proximate benzophenone units to the dibenzobarrelene groups. The isomerization was observed to be regiospecific, and thin films showed alignment.National Science Foundation (U.S.) (DMR-1005810)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-07-D-004
Kanter Revisited: Gender, Power and (In)visibility
No full textThis paper revisits Kanter's (1977) seminal work Men and Women of the Corporation, rereading her account of numerical advantage and disadvantage through a poststructuralist lens which exposes hidden dimensions of gendered power. This lens is captured in the ‘(In)visibility Vortex’ (Lewis and Simpson, 2010) which highlights struggles and tensions around the norm through processes of preservation and concealment within the norm as well as dynamics of revealing, exposure and disappearance as features of the margins. The study draws on developments in feminist theorizing, specially around visibility, invisibility and power, to facilitate this rereading. In so doing, the author demonstrate that while Kanter retreated from explanations based on the gendering of organizations or from recognition of gendered power, these dynamics can be identified in her text. The authors suggest that rereading classic texts can surface dimensions of organizations that have contemporary significance and can inform future research
Hidden dynamics in models of discontinuity and switching
No full textSharp switches in behaviodr, like impacts, stick slip motion, or electrical relays, can be modelled by differential equations with discontinuities. A discontinuity approximates fine details of a switching process that lie beyond a bulk empirical model. The theory of piecewise-smooth dynamics describes what happens assuming we can solve the system of equations across its discontinuity. What this typically neglects is that effects which are vanishingly small outside the discontinuity can have an arbitrarily large effect at the discontinuity itself. Here we show that such behaviour can be incorporated within the standard theory through nonlinear terms, and these introduce multiple sliding modes. We show that the nonlinear terms persist in more precise models, for example when the discontinuity is smoothed out. The nonlinear sliding can be eliminated, however, if the model contains an irremovable level of unknown error, which provides a criterion for systems to obey the standard Filippov laws for sliding dynamics at a discontinuity. (C) 2014 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).</p
Deletion of vitamin D receptor leads to premature emphysema/COPD by increased matrix metalloproteinases and lymphoid aggregates formation
No full textDeficiency of vitamin D is associated with accelerated decline in lung function. Vitamin D is a ligand for nuclear hormone vitamin D receptor (VDR), and upon binding it modulates various cellular functions. The level of VDR is reduced in lungs of patients with chronic obstructive pulmonary disease (COPD) which led us to hypothesize that deficiency of VDR leads to significant alterations in lung phenotype that are characteristics of COPD/emphysema associated with increased inflammatory response. We found that VDR knock-out (VDR(-/-)) mice had increased influx of inflammatory cells, phospho-acetylation of nuclear factor-kappaB (NF-κB) associated with increased proinflammatory mediators, and up-regulation of matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MMP-12 in the lung. This was associated with emphysema and decline in lung function associated with lymphoid aggregates formation compared to WT mice. These findings suggest that deficiency of VDR in mouse lung can lead to an early onset of emphysema/COPD because of chronic inflammation, immune dysregulation, and lung destruction
Positron beam study of annealed silicon nitride films
No full textPositron annihilation spectroscopy has been used to study silicon nitride films grown by plasma-enhanced chemical vapor deposition and annealed at different temperatures. For both silicon-rich and nitrogen-rich films, the positron line shape (S) parameter increases after annealing for 15 min at temperatures up to 700-800 degrees C. This is understood in terms of the fact that removal of the hydrogen by annealing leads to the presence of unpassivated silicon dangling bond sites and vacancy complexes. Annealing at higher temperatures leads to a reduction in the S parameter, consistent with further hydrogen removal producing unpassivated N- sites. (C) 1996 American Institute of Physics.PT: J; CR: ASOKAKUMAR P, 1994, J APPL PHYS, V76, P4935 GOLDBERG RD, 1995, APPL SURF SCI, V85, P287 GOSSMANN HJ, 1992, APPL PHYS LETT, V61, P540 HABRAKEN FHP, 1991, LPCVD SILICON NITRID, P118 HAKVOORT RA, 1991, APPL PHYS LETT, V59, P1687 HAKVOORT RA, 1993, THESIS DELFT U TECHN HEYNS M, 1991, LPCVD SILICON NITRID, P82 LANDFORD WA, 1978, J APPL PHYS, V49, P2473 LANDFORD WA, 1992, NUCL INSTRUM METH B, V66, P65 LANDHEER D, 1995, J APPL PHYS, V78, P2568 LU Z, 1995, J VAC SCI TECHNOL 1, V13, P607 LYNN KG, 1989, CAN J PHYS, V67, P618 MITCHELL LV, 1990, AIP C P, V218, P121 PEROVIC DD, 1991, PHYS REV B, V43, P14257 RUBLOFF GW, 1990, VACUUM, V41, P790 SCHULTZ PJ, 1988, NUCL INSTRUM METH B, V30, P94 SCHULTZ PJ, 1988, PHYS REV LETT, V61, P187 SCHULTZ PJ, 1988, REV MOD PHYS, V60, P701 SIMPSON PJ, 1991, PHYS REV B, V44, P12180 SMITH DL, 1990, J ELECTROCHEM SOC, V137, P614 SMITH DL, 1990, MATER RES SOC S P, V165, P69; NR: 21; TC: 1; J9: J APPL PHYS; PG: 5; GA: TY119Source type: Electronic(1
Bifurcations of piecewise smooth flows:perspectives, methodologies and open problems
No full textIn this paper the theory of bifurcations in piecewise smooth flows is critically surveyed. The focus is on results that hold in arbitrarily (but finitely) many dimensions, highlighting significant areas where a detailed understanding is presently lacking. The clearest results to date concern equilibria undergoing bifurcations at switching boundaries and limit cycles undergoing grazing and sliding bifurcations. After discussing fundamental concepts such as topological equivalence of two piecewise smooth systems, discontinuity-induced bifurcations are defined for equilibria and limit cycles. Conditions for equilibria to exist in n-dimensions are given, followed by the conditions under which they generically undergo codimension-one bifurcations. The extent of knowledge of their unfoldings is also summarized. Codimension-one bifurcations of limit cycles and boundary-intersection crossing are described together with techniques for their classification. Codimension-two bifurcations are discussed with suggestions for further study
Vacancy generation resulting from electrical deactivation of arsenic
No full textElectrical deactivation of arsenic in highly doped silicon has been studied using the positron-beam technique. Direct experimental evidence linking the formation of arsenic-vacancy complexes (i.e., As-n-v) to the deactivation process is reported. The average number of arsenic atoms per complex, (n) over bar>2, was determined by comparing the observed complex concentrations with those of the deactivated arsenic inferred from Hall-effect measurements. (C) 1995 American Institute of Physics.PT: J; CR: AERS GC, 1991, POSITRON BEAMS SOLIE, P162 ALATALO M, 1995, PHYS REV B, V51, P4176 CHU WK, 1980, LASER SOLID INTERACT, P253 DANNEFAER S, 1987, PHYS STATUS SOLIDI A, V102, P481 DLUBEK G, 1987, PHYS STATUS SOLIDI A, V102, P443 FAHEY PM, 1989, REV MOD PHYS, V61, P289 GOETZLICH J, 1985, ION BEAN PROCESSES A, P349 GOLDBERG RD, 1995, APPL SURF SCI, V85, P287 JACKMAN TE, 1989, APPL PHYS A-SOLID, V49, P335 LIETOILA A, 1981, J APPL PHYS, V52, P230 LIETOLA A, 1980, APPL PHYS LETT, V36, P675 LUNING S, 1992, IEDM, P349 LYNN KG, 1979, PHYS REV B, V20, P3566 PANDEY KC, 1988, PHYS REV LETT, V61, P1282 ROUSSEAU PM, 1994, APPL PHYS LETT, V65, P578 SCHULTZ PJ, 1988, NUCL INSTRUM METH B, V30, P94 SCHULTZ PJ, 1988, REV MOD PHYS, V60, P701 SIMPSON PJ, UNPUB; NR: 18; TC: 38; J9: APPL PHYS LETT; PG: 3; GA: TJ304Source type: Electronic(1
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