Publications

Cigarette smokers on average weigh less than nonsmokers. However, among smokers, those who smoke the most weigh the most. To better understand the effects of nicotine on body weight, we investigated the pharmacodynamics of intravenous nicotine and cigarette smoking in low-level smokers (10 or fewer cigarettes per day) and high-level smokers (15 to 30 cigarettes per day). Cigarette smoking and intravenous nicotine increased heart rate and energy expenditure in most smokers. The effects of intravenous nicotine and smoking were of similar magnitude, confirming that the effects of smoking are mediated by nicotine. Nicotine produced a slightly greater increase in heart rate in low-level versus high-level smokers, but energy expenditure increased to a much greater extent in low-level versus high-level smokers. The plots of plasma nicotine concentration versus responses suggest development of acute tolerance to both heart rate acceleration and increased energy expenditure in low-level smokers; high-level smokers show a similar pattern of tolerance for heart rate but show only a brief increase in energy expenditure and a hysteresis curve consistent with either rapid development of tolerance or no effect. Thus there is evidence of differential development or rate of loss of tolerance to cardiovascular versus metabolic effects of nicotine in low-level versus high-level smokers. Pharmacodynamic differences between low-level and high-level smokers may explain, at least in part, the unusual relationship between cigarette consumption and body weight.

Abstract We have studied synchronization mechanism in locally coupled nonlinear oscillators. Here, synchronization takes place by passive coupling based on a reaction–diffusion process. We will compare this mechanism with basic synchronization techniques, showing their similarities and specific properties. In addition to synchronization, passive and local coupling can also ‘awaken’ non‐oscillating cell circuits and trigger oscillation, provided that cells are locally active. This result resembles Turing's and Smale's works showing that locally communicating simple elements can produce very different patterns even if separate elements do not show any activity. This property will be demonstrated for two second‐order cells and also for a large ensemble of oscillatory cells. In latter case, the network of oscillatory cells exhibits very sophisticated spatio‐temporal waves, e.g. spiral waves. Copyright © 2008 John Wiley & Sons, Ltd.

Na-ion batteries have attracted growing attention due to the high abundance and low cost of Na compared with Li. As a promising category of cathode materials for Na-ion batteries, layered oxides have been widely studied. Among the rich diversity of structure, emphasis has been mainly focused on O3 and P2-phases (in Delmas’ denotion 1 . ) Several layered oxides have been studied recently, NaMnO 2 2 , NaNiO 2 3 , Na x CoO 2 4 , Na 2/3 Mn 1/2 Fe 1/2 O 2 5 , etc. For most O3-type oxides, the reversible capacity is limited to 120 mAh/g, corresponding to 0.5 Na per formula unit, while for most P2-type oxides, the reversible capacity is about 160 mAh/g which is equivalent to ≈ 0.67Na extracted and intercalated during cycling. We synthesized a series of O3- and P2-type compounds with the same transition metal components via solid-state reaction and carried out a comparative study between the O3 and P2 structure. Besides performance, we evaluated the structure/valence transition and Na + mobility. The structural transitions during Na + intercalation/deintercalation are similar for most reported O3-type oxides with an O3-P3 transition, while the P2 phases usually experience more reversible phase transitions, accompanied by stacking faults. We carried out in-situ XRD observation to study the structure evolution of our new O3- and P2-type materials. The valence evolution of the transition metals in O3- and P2-type materials was evaluated. A good understanding of the valence evolution of transition metals in layered oxides will benefit the design and tailoring of this category of materials.

Drawing on the Begriffsgeschichte of Reinhart Koselleck and the reflexive sociology of Pierre Bourdieu, my book The Invention of the ‘Underclass’ draws a microhistory of the birth, diffusion, and demise of this racialized folk devil at the intersection of the academic field, the journalistic field, and the politics-policy-philanthropic field. This history illuminates the politics of knowledge about dispossessed and dishonored categories in the metropolis and suggests three notions that can help researchers parse the use and abuse of other social science constructs and thus practice better conceptual hygiene: lemming effects (illustrated by the wild rush to deploy ‘diaspora’), conceptual speculative bubble (as with ‘racial capitalism’), and turnkey problematics (such as the ‘resilient city’ and the ‘creative city’). I discuss the factors that foster the development of epistemic bandwagons, speculation, and turnkeys, and specify the criteria that make for a robust concept in terms of semantics (clarity and neutrality), logics (coherence and type-specificity), and heuristics (empirical adequacy and theoretical productivity).

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.

AbstractMechanisms influencing the ambient temperature mechanical properties of commercial Al–Li alloys 2090, 2091, 8090, and 8091 are examined, with specific emphasis on the role of microstructure. In Part 2, results on fatigue crack propagation behaviour are presented for both ‘long’ (≥ 5 mm) and ‘microstructurally small’ (~1–1000 μm) cracks and compared with behaviour in traditional high strength aluminium alloys. In general, it is found that the growth rates of long fatigue cracks in Al–Li alloys are up to two to three orders of magnitude lower than in traditional 7000 and 2000 series alloys, when compared at an equivalent stress intensity range ∆K. By contrast, corresponding growth rates of microstructurally small fatigue cracks were up to two to three orders of magnitude higher than the long crack results. Such observations are attributed to the prominent role of crack tip shielding in Al–Li alloys resulting from the tortuous and deflected nature of the crack paths which results in a reduced crack tip ‘driving force’ from crack deflection and, more importantly, from the consequent crack closure induced by the wedging of fracture surface asperities. Since microstructurally small cracks are unable to develop the same level of shielding from crack closure by virtue of their limited wake, small crack growth rates are significantly accelerated. Unlike fracture toughness behaviour, artificial aging of commercial Al–Li alloys to peak strength has a mixed influence on the (long crack) resistance. Although behaviour at higher growth rates is relatively unaffected, in 2091 nominal threshold ∆KTH values are increased by 17%, whereas in 8090 and 8091 they are decreased by 16–17%. However, all alloys show reduced effective fatigue thresholds at peak strength after correcting for crack closure.MST/926b

Donation is not from an sp3 orbital: Decomposition analysis, based on absolutely localized molecular orbitals, provides an alternative and somewhat unconventional view of hydrogen bonding in the water dimer. A new description of the electron-donating orbital is uncovered: unlike sp3 lone pairs, a single donor–acceptor orbital pair forms, in which the donating orbital changes its orientation according to the relative positions of the two molecules.

In this paper we study the problem of determining whether two points lie in the same connected component of a semi-algebraic set S. Although we are mostly concerned with sets S ⊆ Rk, our algorithm can also decide if points in an arbitrary set S ⊆ Rk can be joined by joined by a semi-algebraic path, for any real closed field R. Our algorithm computes a one-dimensional semi-algebraic subset R(S) of S (actually of an embedding of S in a space Rk for a certain real extension field R of the given field R. R(S) is called the roadmap of S. The basis of this work is the roadmap algorithm described in [3,4] which worked only for compact, regularly stratified sets.

AbstractA study has been made of the susceptibility to hydrogen attack of a newly developed 3Cr–1 Mo–1Ni pressure-vessel steel, intended for use in coal-conversion vessels, following long-term exposure to high-pressure (14-17 MPa) gaseous hydrogen at 550 and 600°C; the results are compared to the behaviour of 2·25Cr–1Mo steel. To simulate the condition of both surface and mid-section locations of thick-section (400 mm) plate during commercial normalizing, oil quenched and slowly cooled (8 K min−1) structures were examined after tempering at 650 and 700°C, with respect to their strength, ductility, and impact toughness properties. Compared to unexposed samples, structures exposed to hydrogen were observed to show some softening (up to 20% reduction in yield stress) and ‘embrittlement’ (up to 22% reduction in upper-shelf Charpy energies and increases in the transition temperatures by 65–100 K), although there were no visible signs of major microstructural damage. Moreover, the behaviour of the oil-quenched and slow-cooled structures was largely similar. In comparison to 2·25Cr–1 Mo steel, which can become highly susceptible to hydrogen damage in the very slowly cooled state, the present 3Cr–1Mo–1Ni steel was found to have far superior resistance to hydrogen attack. This was attributed primarily to two factors: namely, the increased hardenability, which resulted from the absence of pro-eutectoid ferrite in as-cooled microstructures, and the accelerated kinetics in the carbide precipitation sequence, which resulted in the more rapid replacement of M3C by more stable, higher-alloyed carbides, such as M23C6.MST/95