Melting, vaporization, and energy partitioning for impacts on asteroidal and planetary objects

A three-dimensional smoothed particle hydrodynamics code was used to model normal and oblique impacts of silicate projectiles on asteroidal and planetary bodies. The energy of the system, initially in the kinetic energy of the impactor, is partitioned after impact into internal and kinetic energy of the impactor and the target body. These simulations show that, unlike the case of impacts onto a half-space, a significant amount of energy remains in the kinetic energy of the impacting body, as parts of it travel past the main planet and escape the system. This effect is greater for more oblique impacts, and for impacts onto the small planets. Melting and vaporization of both bodies were also examined. The amount of the target body melted was much greater in the case of smaller targets than for an impact of a similar scale on a larger body

Studies of homogeneous dirhodium catalyst system

Hydroformylation studies were conducted to investigate the effects of various H&sub2;/CO ratios on rac-[Rh&sub2;H&sub2;(μ-CO)&sub2;(et,ph-P4)]²+;, a dirhodium tetraphosphine catalyst system. Similar experiments were also conducted with monometallic catalysts based on BISBI, NAPHOS, and Xantphos, some of the best bisphosphine ligands for hydroformylation catalysis. This was due to the lack of information in literature on the effects of variable ratios and pressures on activities and selectivities of catalysts that contain bisphosphine ligands, and these studies were also used as a basis of comparison for the dirhodium system. Results indicate that the dirhodium system is more efficient with higher H&sub2;/CO ratios (2:1, 90 psig total pressure appears to be near optimum) with good turnover frequencies, high regioselectivities, and lower catalyst fragmentation reactions in comparison to standard 1:1 H&sub2;/CO conditions. The dirhodium catalyst appears to be extremely sensitive to CO induced loss of Rh to deactivate the catalyst. The monometallic systems show that higher H&sub2;/CO ratios increase catalytic activity and yield higher aldehyde regioselectivities, but also increase the percentage of olefin isomerization. The monometallic systems also demonstrate Rh-induced phosphine fragmentation reactions and catalyst decomposition due to the lower CO partial pressures. Due to the increased activity and selectivity obtained when using a 2:1 H&sub2;/CO ratio, in situ high pressure IR studies were conducted to determine if there were any structural differences between the dirhodium catalyst generated at a 1:1 H&sub2;/CO ratio and a 2:1 H&sub2;/CO ratio. Also due to the increased activity and selectivity in 30% water/acetone (by volume) in comparison to acetone, solvent effect studies were conducted to compare structural differences in acetone and 30% water/acetone. Preliminary IR studies suggest that there are not any structural differences in the 2:1 H&sub2;/CO ratio and 30% water/acetone studies in comparison to standard hydroformylation conditions

Theme Overview: Agriculture and Water Quality in the Cornbelt: Overview of Issues and Approaches

Resource /Energy Economics and Policy, Q25,

Effects of physical aging on long-term creep of polymers and polymer matrix composites

For many polymeric materials in use below the glass transition temperature, the long term viscoelastic behavior is greatly affected by physical aging. To use polymer matrix composites as critical structural components in existing and novel technological applications, this long term behavior of the material system must be understood. Towards that end, this study applied the concepts governing the mechanics of physical aging in a consistent manner to the study of laminated composite systems. Even in fiber-dominated lay-ups the effects of physical aging are found to be important in the long-term behavior of the composite. The basic concepts describing physical aging of polymers are discussed. Several aspects of physical aging which have not been previously documented are also explored in this study, namely the effects of aging into equilibrium and a relationship to the time-temperature shift factor. The physical aging theory is then extended to develop the long-term compliance/modulus of a single lamina with varying fiber orientation. The latter is then built into classical lamination theory to predict long-time response of general oriented lamina and laminates. It is illustrated that the long term response can be counterintuitive, stressing the need for consistent modeling efforts to make long term predictions of laminates to be used in structural situations

Efficacy and safety of pharmacotherapies for smoking cessation in anxiety disorders: Subgroup analysis of the randomized, active- and placebo-controlled EAGLES trial.

BackgroundSmoking rates are high in adults with anxiety disorders (ADs), yet little is known about the safety and efficacy of smoking-cessation pharmacotherapies in this group.MethodsPost hoc analyses in 712 smokers with AD (posttraumatic stress disorder [PTSD], n = 192; generalized anxiety disorder [GAD], n = 243; panic disorder [PD], n = 277) and in a nonpsychiatric cohort (NPC; n = 4,028). Participants were randomly assigned to varenicline, bupropion, nicotine-replacement therapy (NRT), or placebo plus weekly smoking-cessation counseling for 12 weeks, with 12 weeks follow-up. General linear models were used to test the effects of treatment group, cohort, and their interaction on neuropsychiatric adverse events (NPSAEs), and continuous abstinence weeks 9-12 (treatment) and 9-24 (follow-up).ResultsNPSAE incidence for PTSD (6.9%), GAD (5.4%), and PD (6.2%) was higher versus NPC (2.1%), regardless of treatment. Across all treatments, smokers with PTSD (odds ratio [OR] = 0.58), GAD (OR = 0.72), and PD (OR = 0.53) had lower continuous abstinence rates weeks 9-12 (CAR9-12) versus NPC. Varenicline demonstrated superior efficacy to placebo in smokers with GAD and PD, respectively (OR = 4.53; 95% confidence interval [CI] = 1.20-17.10; and OR = 8.49; 95% CI = 1.57-45.78); NRT was superior to placebo in smokers with PD (OR = 7.42; 95% CI = 1.37-40.35). While there was no statistically significant effect of any treatment on CAR9-12 for smokers with PTSD, varenicline improved 7-day point prevalence abstinence at end of treatment in this subcohort.ConclusionIndividuals with ADs were more likely than those without psychiatric illness to experience moderate to severe NPSAEs during smoking-cessation attempts, regardless of treatment. While the study was not powered to evaluate abstinence outcomes with these subgroups of smokers with ADs, varenicline provided significant benefit for cessation in those with GAD and PD, while NRT provided significant benefit for those with PD

SPATIOTEMPORAL AND JOINT KINEMATIC DIFFERENCES BETWEEN FOOTSTRIKE PATTERNS IN MALE AND FEMALE 10,000M ATHLETES

The aim of this study was to examine biomechanical differences between footstrike patterns in elite 10,000m racing. Video data of 53 men and 33 women were recorded in competition and used to compare spatiotemporal and joint kinematic variables between rearfoot, midfoot and forefoot strikers, and to find associations. There were no differences between footstrike patterns for speed, step length or cadence, but rearfoot strikers had longer contact times than forefoot and midfoot strikers by 0.017 and 0.014 s, respectively, and shorter flight times by 0.023 and 0.021 s, respectively. The main causes of different footstrike patterns were the ankle and foot angles at initial contact; thigh, knee and shank angles differed little. In women, longer hip-ankle “overstriding” distances were associated with faster running speeds (r = 0.58), and so were a positive contributor to performance

An Integrative Design Methodology to Support an Inter-Organizational Knowledge Management Solution

Design research develops knowledge to respond to real-world challenges and solve authentic problems. In this paper, we adopt a pragmatic and semantic design approach to combine the best of two separate design discourses: the discourse about developing science-based design rules and the discourse on user-centered, participative, and experience-based design. We develop a methodology that combines both discourses and perspectives. Subsequently, this methodology is illustrated by means of a case study of designing and developing a portal for mapping competencies in the multi-stakeholder environment of an IT cluster. This case study suggests design research can become more effective if it adopts a deliberate focus on articulating design rules as well as engaging users in trying out prototypes, to create artifacts that support and drive the dialogue between user-practitioners and design-oriented researchers

Mathematics and Morphogenesis of the City: A Geometrical Approach

Cities are living organisms. They are out of equilibrium, open systems that never stop developing and sometimes die. The local geography can be compared to a shell constraining its development. In brief, a city's current layout is a step in a running morphogenesis process. Thus cities display a huge diversity of shapes and none of traditional models from random graphs, complex networks theory or stochastic geometry takes into account geometrical, functional and dynamical aspects of a city in the same framework. We present here a global mathematical model dedicated to cities that permits describing, manipulating and explaining cities' overall shape and layout of their street systems. This street-based framework conciliates the topological and geometrical sides of the problem. From the static analysis of several French towns (topology of first and second order, anisotropy, streets scaling) we make the hypothesis that the development of a city follows a logic of division / extension of space. We propose a dynamical model that mimics this logic and which from simple general rules and a few parameters succeeds in generating a large diversity of cities and in reproducing the general features the static analysis has pointed out.Comment: 13 pages, 13 figure

The District Role in Instructional Improvement

Are changing conditions affecting the capacity of districts to provide focus, to coordinate support, and to scale up successful reforms? From a study of the roles played by central office staff members in shaping and supporting instructional reforms in three large urban districts, the authors derive an answer

A Tale of Three Watersheds: Nonpoint Source Pollution and Conservation Practices across Iowa

Resource /Energy Economics and Policy, Q25,