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

CPD damage recognition by transcribing RNA polymerase II.

Cells use transcription-coupled repair (TCR) to efficiently eliminate DNA lesions such as ultraviolet light–induced cyclobutane pyrimidine dimers (CPDs). Here we present the structure-based mechanism for the first step in eukaryotic TCR, CPD-induced stalling of RNA polymerase (Pol) II. A CPD in the transcribed strand slowly passes a translocation barrier and enters the polymerase active site. The CPD 5′-thymine then directs uridine misincorporation into messenger RNA, which blocks translocation. Artificial replacement of the uridine by adenosine enables CPD bypass; thus, Pol II stalling requires CPD-directed misincorporation. In the stalled complex, the lesion is inaccessible, and the polymerase conformation is unchanged. This is consistent with nonallosteric recruitment of repair factors and excision of a lesion-containing DNA fragment in the presence of Pol II

Multifractal properties of critical eigenstates in two-dimensional systems with symplectic symmetry

The multifractal properties of electronic eigenstates at the metal-insulator transition of a two-dimensional disordered tight-binding model with spin-orbit interaction are investigated numerically. The correlation dimensions of the spectral measure $\widetilde{D}_{2}$ and of the fractal eigenstate $D_{2}$ are calculated and shown to be related by $D_{2}=2\widetilde{D}_{2}$. The exponent $\eta=0.35\pm 0.05$ describing the energy correlations of the critical eigenstates is found to satisfy the relation $\eta=2-D_{2}$.Comment: 6 pages RevTeX; 3 uuencoded, gzipped ps-figures to appear in J. Phys. Condensed Matte

Drawing Graphs within Restricted Area

We study the problem of selecting a maximum-weight subgraph of a given graph such that the subgraph can be drawn within a prescribed drawing area subject to given non-uniform vertex sizes. We develop and analyze heuristics both for the general (undirected) case and for the use case of (directed) calculation graphs which are used to analyze the typical mistakes that high school students make when transforming mathematical expressions in the process of calculating, for example, sums of fractions

Metal-insulator transition in a multilayer system with a strong magnetic field

We study the Anderson localization in a weakly coupled multilayer system with a strong magnetic field perpendicular to the layers. The phase diagram of 1/3 flux quanta per plaquette is obtained. The phase diagram shows that a three-dimensional quantum Hall effect phase exists for a weak on-site disorder. For intermediate disorder, the system has insulating and normal metallic phases separated by a mobility edge. At an even larger disorder, all states are localized and the system is an insulator. The critical exponent of the localization length is found to be $\nu=1.57\pm0.10$.Comment: Latex file, 3 figure

Self-Averaging, Distribution of Pseudo-Critical Temperatures and Finite Size Scaling in Critical Disordered Systems

The distributions $P(X)$ of singular thermodynamic quantities in an ensemble of quenched random samples of linear size $l$ at the critical point $T_c$ are studied by Monte Carlo in two models. Our results confirm predictions of Aharony and Harris based on Renormalization group considerations. For an Ashkin-Teller model with strong but irrelevant bond randomness we find that the relative squared width, $R_X$, of $P(X)$ is weakly self averaging. $R_X\sim l^{\alpha/\nu}$, where $\alpha$ is the specific heat exponent and $\nu$ is the correlation length exponent of the pure model fixed point governing the transition. For the site dilute Ising model on a cubic lattice, known to be governed by a random fixed point, we find that $R_X$ tends to a universal constant independent of the amount of dilution (no self averaging). However this constant is different for canonical and grand canonical disorder. We study the distribution of the pseudo-critical temperatures $T_c(i,l)$ of the ensemble defined as the temperatures of the maximum susceptibility of each sample. We find that its variance scales as $(\delta T_c(l))^2 \sim l^{-2/\nu}$ and NOT as $\sim l^{-d}. We find that$R_\chi$is reduced by a factor of$\sim 70$with respect to$R_\chi (T_c)$by measuring$\chi$of each sample at$T_c(i,l)$. We analyze correlations between the magnetization at criticality$m_i(T_c,l)$and the pseudo-critical temperature$T_c(i,l)$in terms of a sample independent finite size scaling function of a sample dependent reduced temperature$(T-T_c(i,l))/T_c$. This function is found to be universal and to behave similarly to pure systems.Comment: 31 pages, 17 figures, submitted to Phys. Rev.

Trait self-control and beliefs about the utility of emotions for initiatory and inhibitory self-control

How do people with high trait self-control achieve their success? This research aimed to provide evidence for beliefs about emotion utility as a potential mechanism. Specifically, because beliefs about the utility of emotions predict emotion regulation and successful performance, we investigate the hypothesis that trait self-control influences beliefs about the utility of emotions for self-control. Two preregistered studies examined whether beliefs about the utility of emotions in everyday self-control situations varied depending on the person (trait self-control) and the situation (initiatory or inhibitory self-control). Our key finding was that people considered positive emotions more useful for self-control than negative emotions. This effect was also moderated by situational and individual factors, such that positive emotions were considered especially useful by participants with high trait self-control and in situations requiring initiatory self-control (with the opposite effect for negative emotions). This research suggests a potential role for instrumental emotion regulation in self-control success

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

Quantum Hall Effect in Three Dimensional Layered Systems

Using a mapping of a layered three-dimensional system with significant inter-layer tunneling onto a spin-Hamiltonian, the phase diagram in the strong magnetic field limit is obtained in the semi-classical approximation. This phase diagram, which exhibit a metallic phase for a finite range of energies and magnetic fields, and the calculated associated critical exponent, $\nu=4/3$, agree excellently with existing numerical calculations. The implication of this work for the quantum Hall effect in three dimensions is discussed.Comment: 4 pages + 4 figure