Harnessing the need for immediate gratification: Cognitive reconstrual modulates the reward value of temptations.

Many of us succumb to temptations, despite knowing that we will later regret doing so. How can such behavior be avoided? In three studies, the authors tested the hypothesis that reconstruing temptation as a test of a valued internal quality ("willpower") would decrease the tendency to succumb by reducing the appeal of the temptation. In Study 1, participants who construed a challenging handgrip task as a test of willpower resisted the temptation to terminate the painful task longer than participants who did not. In Study 2, participants performed a handgrip task twice. Only participants who changed their construal of the task into a test of willpower improved their performance. In Study 3, participants took a timed math test while being tempted by comedy clips. Participants who reconstrued the situation as willpower test compared with participants who did not, (a) enjoyed the videos less, and (b) were better able to resist the tempting videos. These studies demonstrate that cognitive reconstrual can be used to modify reward contingencies, so that succumbing to temptation becomes less appealing, and resisting temptation becomes more appealing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Active contours: Generalization of the snake mode

Abstract— Segmentation is one of the fundamental issues in the field of image processing and computer vision. Various approaches include differentiating an object in the image as a final goal or for further processing (medical diagnosis, surveillance, 3‐D reconstruction and more). Snakes, a model proposed by Kass, Witkin, and Terzopoulos in 1987, provides an efficient method for segmenting an object through the minimization of its energy. The advantage of snakes is in its ability to use high‐level data given by the algorithm operator, as opposed to other methods such as the Laplace technique. The snakes model inherently imposes strong constraints on a given image in order to successfully segment an object. In this paper, the use of adjustment methods is described, which allow us to generalize the snake model to a wider range of applications. Through the use of pre‐processing techniques, the model's constraints were softened. The main theoretical model and its use in facing a real life image is presented.     

Te-seeded growth of few-quintuple layer Bi2Te3 nanoplates

We report on a Te-seeded epitaxial growth of ultrathin Bi2Te3 nanoplates （down to three quintuple layers （QL）） with large planar sizes （up to tens of micrometers） through vapor transport. Optical contrast has been systematically investigated for the as-grown Bi2Te3 nanoplates on the SiO2/Si substrates, experimentally and computationally. The high and distinct optical contrast provides a fast and convenient method for the thickness determination of few-QL Bi2Te3 nanoplates. By aberration-corrected scanning transmission electron microscopy, a hexagonal crystalline structure has been identified for the Te seeds, which form naturally during the growth process and initiate an epitaxial growth of the rhombohedral- structured Bi2Te3 nanoplates. The epitaxial relationship between Te and Bi2T% is identified to be perfect along both in-plane and out-of-plane directions of the layered nanoplate. Similar growth mechanism might be expected for other bismuth chalcogenide layered materials.     

Twinning‐, Polytypism‐, and Polarity‐Induced Morphological Modulation in Nonplanar Nanostructures with van der Waals Epitaxy

Twinning, polytypism, and polarity are important aspects in nanostructural growth since their presence can affect various properties of the as‐grown products. The morphology of nanostructures grown via van der Waals epitaxy is shown to be strongly influenced by the twinning density and the presence of polytypism within the nanostructures, while the growth direction is driven by the compound polarity. With ZnTe as the model material, vertically aligned nanorods are successfully produced with variable cross‐section and branched crystals (tripods and tetrapods) on only a single type of substrate. Van der Waals epitaxy contributes by relaxing the lattice‐mismatch requirements for epitaxial growth and by enabling a variety of crystal planes in the initial stages of the growth to be interfaced to the substrate, regardless of the polarity of the epitaxial material. These results may provide more flexibility in tuning rationally the morphology of epitaxial nanostructures into other shapes with higher complexity by routine adjustment of growth environment.     

Toward a Model for Backtracking and Dynamic Programming

We propose a model called priority branching trees (pBT) for backtracking and dynamic programming algorithms. Our model generalizes both the priority model of Borodin, Nielson and Rackoff, as well as a simple dynamic programming model due to Woeginger, and hence spans a wide spectrum of algorithms. After witnessing the strength of the model, we then show its limitations by providing lower bounds for algorithms in this model for several classical problems such as Interval Scheduling, Knapsack and Satisfiability.     

Three-dimensional multiple-order twinning of self-catalyzed GaAs nanowires on Si substrates

In this paper we introduce a new paradigm for nanowire growth that explains the unwanted appearance of parasitic nonvertical nanowires. With a crystal structure polarization analysis of the initial stages of GaAs nanowire growth on Si substrates, we demonstrate that secondary seeds form due to a three-dimensional twinning phenomenon. We derive the geometrical rules that underlie the multiple growth directions observed experimentally. These rules help optimizing nanowire array devices such as solar or water splitting cells or of more complex hierarchical branched nanowire devices.     

Composite phenolic resin-based carbon molecular sieve membranes for gas separation

Composite carbon molecular sieve membranes (c-CMSM) were prepared from phenolic resin loaded with boehmite by a single dipping–drying–pyrolysis step. The composite membrane was analyzed by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, mercury porosimetry, CO₂ adsorption and permeation experiments. It was produced a 2 μm thick composite uniform layer on top of a α-Al₂O₃ support. The composite top layer exhibited nanowires of Al₂O₃ 1–2 nm thick and 10–30 nm long well dispersed in a microporous carbon matrix. The micropores network accounted for 63% of the total pore volume (DR isotherm). The c-CMSM exhibited ideal O₂/N₂ and C₃H₆/C₃H₈ permselectivities of 5 and 15, respectively. The performance of the c-CMSM for pair C₃H₆/C₃H₈ was above the upper bound curve for polymeric membranes, making it a promising vehicle for olefin purification.     

The stability chart of double-diffusive processes with parallel flows — construction by the Galerkin and continuation methods

Summary The stability of an infinite fluid layer subject to arbitrary horizontal flow and to arbitrary vertical temperature and salinity distributions is considered. Linear stability analysis is used to investigate the stability under general three-dimensional perturbations.A general discussion of the properties of the stability chart, using only the governing equations, but not their solution for any particular case, is presented in [1]. This paper contributes a numerical scheme, based on a combination of the Galerkin and the continuation methods, to obtain the stability chart from the characteristic equation. The method is applied to an example with a parabolic velocity distribution and linear temperature and salinity fields. The stability chart in the plane of the Rayleigh numbers is obtained for the region corresponding to solar ponds.     

月恋扬州夜 灯映瘦西湖 瘦西湖之夜亮化工程

在古典园林中,利用自然环境,结合现代灯光,营造充满诗情画意的月夜风景,再现“天下三分明月夜,二分无赖是扬州”的盛况。     

Suppression of three dimensional twinning for a 100% yield of vertical GaAs nanowires on silicon

Multiple seed formation by three-dimensional twinning at the initial stages of growth explains the manifold of orientations found when self-catalyzed GaAs nanowires grow on silicon. This mechanism can be tuned as a function of the growth conditions by changing the relative size between the GaAs seed and the Ga droplet. We demonstrate how growing under high V/III ratio results in a 100% yield of vertical nanowires on silicon(111). These results open up the avenue towards the efficient integration of III-V nanowire arrays on the silicon platform.