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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) \nspectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at \nUV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity \nto examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline (Δm15(B) = 1.69 ± 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.
Vapor−liquid equilibria for dendritic-polymer solutions were obtained using a classic gravimetric-sorption method; the amount of solvent absorbed by the dendrimer was measured as a function of solvent vapor pressure. Three series of dendrimers, each with the same tertiary amine core structure, but different surface groups, were investigated in a variety of organic solvents in the range 50−75 °C. The dendrimer surface groups were dodecylamines, octadecyl amides, and polyisobutylene. Solvent absorption depends strongly on dendrimer composition and generation number.
Abstract An effective procedure is summarized without derivation for estimating the maximum response of a class of torsionally‐coupled, multi‐storey buildings due to earthquake ground motion characterized by response spectra. The analysis procedure is shown to be efficient and to provide insight into torsional coupling effects because the maximum response of such a torsionally‐coupled, N ‐storey building in its nj th mode of vibration is determined exactly by analysing (i) the response in the j th vibration mode ( j = 1,2, N ) of the corresponding torsionally‐uncoupled, N ‐storey system; and (ii) the response in the n th vibration mode ( n = 1, 2 for a one‐way symmetric plan) of an associated torsionally‐coupled, one‐storey system. It is also demonstrated that an earlier, simpler approach in which the total (considering all vibration modes) response of the building is determined from the total response of the two simpler systems is strictly valid only under restrictive conditions, which are identified, but the simpler approach leads to results that are accurate to a useful degree.
Modern distributed and networked systems are highly heterogeneous in many dimensions, including available bandwidth, processor speed, disk capacity, security, failure rate, and pattern of failures. The theme of this dissertation is that this heterogeneity can not only be handled, but rather should generally be viewed as an asset. We begin by introducing a framework, the price of heterogeneity, to model the effect of heterogeneity in parallel and distributed systems. Our results in this framework show broad classes of systems in which heterogeneity cannot be a disadvantage. We then develop practical methods for distributed systems to adapt to and take advantage of heterogeneity. The U0 distributed hash table achieves improved load balance, route length, and congestion with low overhead in environments with heterogeneous node capacities, such as bandwidth or processing speed. Addressing heterogeneity in reliability, we show that randomization in node selection strategies typically reduces failure rates—a property that permits better understanding of subtle properties of existing systems, as well as the design of new systems. Finally, we study how to improve stability in the Internet's inter-domain routing protocol, while carefully managing tradeoffs with network operators' perferred routes. These results show how both performance and reliability can be improved in heterogeneous environments.
This study investigated preferential encoding of threat material in subjects with posttraumatic stress disorder (PTSD) with a modified dot-probe paradigm. This paradigm indexes attentional bias by measuring response latency to name neutral target words that are presented adjacent to or distant from threat words. Motor vehicle accident survivors with PTSD (n = 15), subclinical PTSD (n = 15), and low anxiety (n = 15) were required to name target words that were presented either adjacent to or distant from strong threat, mild threat, positive, and neutral words. PTSD subjects named targets faster when they were in close proximity to mild threat words. Results suggested that PTSD subjects' attention was drawn to the mild threat stimuli and are discussed in the context of network models of PTSD.
A new rate law for the growth of anodic passive films on metal surfaces is derived from the point defect model (PDM). The model recognizes both the growth of the barrier oxide layer into the metal via the generation of oxygen vacancies at the metal/film interface and the dissolution of the barrier layer at the film/solution interface. The new rate law accounts for the existence of a steady state in film thickness, as well as for the transients in thickness and film growth current as the potential is stepped in the positive or negative direction from an initial steady state. The predictions of the PDM, with respect to the thickness of the barrier layer, are compared with those of the high field model. The latter cannot account for the existence of steady states or the decrease in barrier layer thickness on stepping the potential in the negative direction. The predicted transients in film thickness and growth current density are in good fidelity with the measured transients on tungsten in pH 1.5 phosphate buffer solution as the voltage is cycled between 10 V in reference to saturated calomel electrode and 6 Finally, the new rate law accounts for passive film thinning under negative potential step conditions as the pH is changed over the range of 1.5 to 5.1 and as the initial and final voltages are changed in a systematic manner, such that the voltage excursion is constant. © 2001 The Electrochemical Society. All rights reserved.
Mildly acidic OH groups undergo transition-metal-catalyzed reversible addition across the CC bonds of cyclic and acyclic dienes. For example, the simple complex [Pd(PPh3)4] (1 mol %) effectively catalyzes both the forward addition of phenol across dienes and the reverse elimination of phenol from allylic ethers (see scheme). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z52621_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
