The Effect Of Plasma-deposited Polymers On The Nucleate Boiling Behavior Of Copper Heat Transfer Surfaces

The effect of plasma deposited polymers on the nucleate boiling behavior of copper heat transfer surfaces, using water as the boiling liquid, was determined. The monomers used were tetrafluoroethylene (TFE) and methane. It was found that an 18 nm thick coating of TFE enhanced the nucleate boiling, while a 150 nm thick coating reduced the nucleate boiling. Both 15 nm and 150 nm thick coatings of methane reduced the nucleate boiling, with the effect being more pronounced with the thicker coating. A surface energy effect is postulated to explain the enhanced boiling observed. © 1981

Preparation And Characterization Of Composite Hollow Fiber Reverse Osmosis Membranes By Plasma Polymerization. 1. Design Of Plasma Reactor And Operational Parameters

Composite hollow fiber reverse osmosis membranes were prepared by depositing a thin layer (10-50 nm) of plasma polymers on hollow fibers with porous walls (made of polysulfone). The coating was carried out in a semicontinuous manner with six strands of substrate fibers. Operational parameters which influence reverse osmosis characteristics of composite membranes were investigated. © 1984, American Chemical Society. All rights reserved

Impact Of Sleep Restriction And Recovery On Motivation During Repeated Cognitive Performance Testing

Introduction: Both motivation and sleep deprivation affect cognitive performance. Especially during long-lasting studies with repeated cognitive performance tasks there is concern that subjects will lose motivation over time. Results may be confounded due to changes in motivation. Methods: In an ongoing study, 29 healthy volunteers performed 55 cognitive performance tasks at three-hourly intervals in a 12-day inpatient study. After two baseline nights with 8 h time in bed (TIB) the intervention group (N=20; mean age 26 ± 4 years, 9 females) underwent chronic sleep restriction for 5 nights (5 h TIB) with a following recovery night of 8 h TIB. The control group (N=9; mean age 25 ± 5 years, 3 females) had the opportunity to sleep 8 hours every night. Participants completed the Karolinska Sleepiness Scale (KSS) and a questionnaire about their motivation (from 1=very little/not motivated to 5=very motivated) at 6 p.m. on all days. Results: Wilcoxon signed-rank tests showed a significant decrease in motivation (p=.0439) and a significant increase in subjective sleepiness (p=.0184) from baseline (motivation: 2.8 ± 0.6 (SD), sleepiness: 3.2 ± 1.2) to the last day of chronic sleep restriction (motivation: 2.2 ± 0.5, sleepiness: 5.1 ± 1.8) for the experimental group. Motivation remained low after recovery sleep (2.2 ± 0.8; p=.0198). Sleepiness and motivation scores showed a significant Spearman correlation (r=-0.43, p<0.001). Discussion: Chronic sleep restriction for five days leads to an increase in sleepiness and a decrease in motivation. One night of recovery is insufficient to reverse the motivation loss, contrasting with the beneficial effect on sleepiness. During chronic sleep restriction conditions subjective motivation seems to decrease as a function of subjective sleepiness

Wilde Urbaniten: Tier-Mensch-Regime im Habitat Großstadt

Die rechtlich-administrative und räumlich-planende Regulation des Vorkommens wildlebender Tiere im urbanen Raum lässt sich drei historisch gewachsenen Regimen zuordnen: Das Regime der Hygiene konstituiert die wilden Tiere der Stadt als Schädlinge, Lästlinge oder Nützlinge, das der Jagd als Nutzwild, Raubwild oder Raubzeug und das des Naturschutzes als Schutzobjekte, als heimisch oder fremd und als Leistungsträger oder Schädlinge. Dieses Regimedenken wandelt sich derzeit in der räumlichen Planungspraxis. Es wird mit Ansätzen eines integrierenden, die Wirkmächtigkeit von Tieren anerkennenden und nutzenden sowie offensiv-gestaltenden Umgangs mit Tieren experimentiert. Die interdisziplinäre Planungsmethode Animal-Aided Design berücksichtigt Tiere im Planungsprozess als Akteure, die urbane Räume aktiv mitgestalten und die Lebensqualität in der Stadt aufwerten

Congested Traffic States in Empirical Observations and Microscopic Simulations

We present data from several German freeways showing different kinds of congested traffic forming near road inhomogeneities, specifically lane closings, intersections, or uphill gradients. The states are localized or extended, homogeneous or oscillating. Combined states are observed as well, like the coexistence of moving localized clusters and clusters pinned at road inhomogeneities, or regions of oscillating congested traffic upstream of nearly homogeneous congested traffic. The experimental findings are consistent with a recently proposed theoretical phase diagram for traffic near on-ramps [D. Helbing, A. Hennecke, and M. Treiber, Phys. Rev. Lett. {\bf 82}, 4360 (1999)]. We simulate these situations with a novel continuous microscopic single-lane model, the ``intelligent driver model'' (IDM), using the empirical boundary conditions. All observations, including the coexistence of states, are qualitatively reproduced by describing inhomogeneities with local variations of one model parameter. We show that the results of the microscopic model can be understood by formulating the theoretical phase diagram for bottlenecks in a more general way. In particular, a local drop of the road capacity induced by parameter variations has practically the same effect as an on-ramp.Comment: Now published in Phys. Rev. E. Minor changes suggested by a referee are incorporated; full bibliographic info added. For related work see http://www.mtreiber.de/ and http://www.helbing.org

Fraction of uninfected walkers in the one-dimensional Potts model

The dynamics of the one-dimensional q-state Potts model, in the zero temperature limit, can be formulated through the motion of random walkers which either annihilate (A + A -> 0) or coalesce (A + A -> A) with a q-dependent probability. We consider all of the walkers in this model to be mutually infectious. Whenever two walkers meet, they experience mutual contamination. Walkers which avoid an encounter with another random walker up to time t remain uninfected. The fraction of uninfected walkers is investigated numerically and found to decay algebraically, U(t) \sim t^{-\phi(q)}, with a nontrivial exponent \phi(q). Our study is extended to include the coupled diffusion-limited reaction A+A -> B, B+B -> A in one dimension with equal initial densities of A and B particles. We find that the density of walkers decays in this model as \rho(t) \sim t^{-1/2}. The fraction of sites unvisited by either an A or a B particle is found to obey a power law, P(t) \sim t^{-\theta} with \theta \simeq 1.33. We discuss these exponents within the context of the q-state Potts model and present numerical evidence that the fraction of walkers which remain uninfected decays as U(t) \sim t^{-\phi}, where \phi \simeq 1.13 when infection occurs between like particles only, and \phi \simeq 1.93 when we also include cross-species contamination.Comment: Expanded introduction with more discussion of related wor

Double Beta Decay: Historical Review of 75 Years of Research

Main achievements during 75 years of research on double beta decay have been reviewed. The existing experimental data have been presented and the capabilities of the next-generation detectors have been demonstrated.Comment: 25 pages, typos adde

Longitudinal Experience-Wide Association Studies-A Framework for Studying Personality Change

The importance of personality for predicting life outcomes in the domains of love, work, and health is well established, as is evidence that personality traits, while relatively stable, can change. However, little is known about the sources and processes that drive changes in personality traits and how such changes might impact important life outcomes. In this paper, we make the case that the research paradigms and methodological approaches commonly used in personality psychology need to be revised to advance our understanding of the sources and processes of personality change. We proposeLongitudinal Experience-Wide Association Studiesas a framework for studying personality change that can address the limitations of current methods, and we discuss strategies for overcoming some of the challenges associated withLongitudinal Experience-Wide Association Studies.Peer reviewe