Controlled Elemental Depth Profile in Sol–Gel-Derived PZT Films

Elemental depth profiles of PZT films prepared by two sol–gel formulations, differing in the zirconium precursor stabilization, were investigated by SIMS analysis. Early decomposition of the zirconium precursor yielded opposing gradients of zirconium and titanium, while simultaneous late decomposition of zirconium and titanium precursors provided profile uniformity. The gradients formed during initial crystallization are irreversible. Both types of films showed excellent hysteresis; however, uniform films exhibited a much higher dielectric constant, indicating superior piezoelectric properties. Non-uniform films displayed a complex CV pattern, consistent with an inhomogeneous structure. Finally, thermal decomposition of the individual metal precursors is crucial for controlling film uniformity.     

A zeolite/polymer membrane for separation of ethanol-water azeotrope

A novel membrane effective in the separation of ethanol-water mixtures by pervaporation was made by combining zeolite NaA and poly(vinyl chloride) modified by 2-(2′-butoxyethoxy)ethyl thiolate. Under ambient conditions, a separation factor (α) of 29 and pervaporability (P) of 4 × 10^?4 g m^?1 h^?1 were obtained for the azeotropic mixture whereas, in the absence of zeolite, the respective values were 7 and 7 × 10^?5. A mechanism was proposed relating the preferential water transport at ≈? 50% zeolite content to an interfacial “phase” between the zeolite and the modified polymer.     

Path Hitting in Acyclic Graphs

An instance of the path hitting problem consists of two families of paths, and ℋ, in a common undirected graph, where each path in ℋ is associated with a non-negative cost. We refer to and ℋ as the sets of demand and hitting paths, respectively. When p∈ℋ and share at least one mutual edge, we say that p hits q. The objective is to find a minimum cost subset of ℋ whose members collectively hit those of . In this paper we provide constant factor approximation algorithms for path hitting, confined to instances in which the underlying graph is a tree, a spider, or a star. Although such restricted settings may appear to be very simple, we demonstrate that they still capture some of the most basic covering problems in graphs. Our approach combines several novel ideas: We extend the algorithm of Garg, Vazirani and Yannakakis (Algorithmica, 18:3–20, 1997) for approximate multicuts and multicommodity flows in trees to prove new integrality properties; we present a reduction that involves multiple calls to this extended algorithm; and we introduce a polynomial-time solvable variant of the edge cover problem, which may be of independent interest. An extended abstract of this paper appeared in Proceedings of the 14th Annual European Symposium on Algorithms, 2006. This work is part of D. Segev’s Ph.D. thesis prepared at Tel-Aviv University under the supervision of Prof. Refael Hassin.     

Analysis of the interaction between the dendritic conductance density and activated area in modulating alpha-motoneuron EPSP: statistical computer model

Five reconstructed alpha-motoneurons (MNs) are simulated under physiological and morphological realistic parameters. We compare the resulting excitatory postsynaptic potential (EPSP) of models, containing voltage-dependent channels on the dendrites, with the EPSP of a passive MN and an active soma and axon model. In our simulations, we apply three different distribution functions of the voltage-dependent channels on the dendrites: a step function (ST) with uniform spatial dispersion; an exponential decay (ED) function, with proximal to the soma high-density location; and an exponential rise (ER) with distally located conductance density. In all cases, the synaptic inputs are located as a gaussian function on the dendrites. Our simulations lead to eight key observations. (1) The presence of the voltage-dependent channels conductance (g(Active)) in the dendrites is vital for obtaining EPSP peak boosting. (2) The mean EPSP peaks of the ST, ER, and ED distributions are similar when the ranges of G (total conductance) are equal. (3) EPSP peak increases monotonically when the magnitude of g(Na_step) (maximal g(Na) at a particular run) is increased. (4) EPSP kinetics parameters were differentially affected; time integral was decreased monotonically with increased g(Na_step), but the rate of rise (the decay time was not analyzed) does not show clear relations. (5) The total G can be elevated by increasing the number of active dendrites; however, only a small active area of the dendritic tree is sufficient to get the maximal boosting. (6) The sometimes large variations in the parameters values for identical G depend on the g(Na_step) and active dendritic area. (7) High g(Na_step) in a few dendrites is more efficient in amplifying the EPSP peak than low g(Na_step) in many dendrites. (8) The EPSP peak is approximately linear with respect to the MNs' R(N) (input resistance).     

Superior Thermoelectric Performance of Textured Ca3Co4−xO9+δ Ceramic Nanoribbons

Calcium cobaltite Ca₃Co_4−xO_9+δ (CCO) is a promising p-type thermoelectric (TE) material for high-temperature applications in air. The grains of the material exhibit strong anisotropic properties, making texturing and nanostructuring mostly favored to improve thermoelectric performance. On the one hand multitude of interfaces are needed within the bulk material to create reflecting surfaces that can lower the thermal conductivity. On the other hand, low residual porosity is needed to improve the contact between grains and raise the electrical conductivity. In this study, CCO fibers with 100% flat cross sections in a stacked, compact form are electrospun. Then the grains within the nanoribbons in the plane of the fibers are grown. Finally, the nanoribbons are electrospun into a textured ceramic that features simultaneously a high electrical conductivity of 177 S cm⁻¹ and an immensely enhanced Seebeck coefficient of 200 µV K⁻¹ at 1073 K are assembled. The power factor of 4.68 µW cm⁻¹ K⁻² at 1073 K in air surpasses all previous CCO TE performances of nanofiber ceramics by a factor of two. Given the relatively high power factor combined with low thermal conductivity, a relatively large figure-of-merit of 0.3 at 873 K in the air for the textured nanoribbon ceramic is obtained.     

Inferring global pereeptual contours from local features

We address the problem of contour inference from partial data, as obtained from state-of-the-art edge detectors.We argue that in order to obtain more pereeptually salient contours, it is necessary to impose generic constraints such as continuity and co-curvilinearity.The implementation is in the form of a convolution with a mask which encodes both the orientation and the strength of the possible continuations. We first show how the mask, called the Extension field is derived, then how the contributions from different sites are collected to produce a saliency map.We show that the scheme can handle a variety of input data, from dot patterns to oriented edgels in a unified manner, and demonstrate results on a variety of input stimuli.We also present a similar approach to the problem of inferring contours formed by end points. In both cases, the scheme is non-linear, non iterative, and unified in the sense that all types of input tokens are handled in the same manner.This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Air Force Office of Scientific Research under Contract No. F49620-90-C-0078, and by a NSF Grant under award No. IRI-9024369. The United States Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation hereon.     

A fluid approach to large volume job shop scheduling

We consider large volume job shop scheduling problems, in which there is a fixed number of machines, a bounded number of activities per job, and a large number of jobs. In large volume job shops it makes sense to solve a fluid problem and to schedule the jobs in such a way as to track the fluid solution. There have been several papers which used this idea to propose approximate solutions which are asymptotically optimal as the volume increases. We survey some of these results here. In most of these papers it is assumed that the problem consists of many identical copies of a fixed set of jobs. Our contribution in this paper is to extend the results to the far more general situation in which the many jobs are all different. We propose a very simple heuristic which can schedule such problems. We discuss asymptotic optimality of this heuristic, under a wide range of previously unexplored situations. We provide a software package to explore the performance of our policy, and present extensive computational evidence for its effectiveness.     

B2B Procurement and Marketplace Transformation

Emerging web technologies and systems have started a revolutionary path that will have a profound impact on procurement processes and systems, especially in the area of indirect procurement and the management of operating resources. In fact, what started as more narrowly focused procurement systems only a couple of years ago, has transformed into a web of technologies, markets, and business strategies that have ramifications well beyond the purchasing function. The focus of this paper is on the marketplace structure, functionality and capabilities of systems, and key factors that buyers need to take into consideration when transforming their procurement processes. Contents management, markets, standards, and outsourcing are important problems that are discussed in this paper.     

A simple velocity-free controller for attitude regulation of a spacecraft with delayed feedback

In this note, we consider the application of a velocity-free controller for attitude regulation of a rigid spacecraft with gas jet actuators when the effects of time-delays in the feedback loop are taken into consideration. Simple sufficient conditions for exponential stability are presented. Some structural properties of the resulting closed-loop system are studied, and relevant design tools are demonstrated.     

An Oral Mixed Fat Load Is Followed by a Modest Anti-inflammatory Adipocytokine Response in Overweight Patients with Metabolic Syndrome

We investigated the postprandial changes in plasma levels of adipocytokines in overweight patients with metabolic syndrome after an oral fat load. After an oral fat load and during a prolonged fast, blood was drawn at 0, 2, 3, 4 and 8 h for measurement of adiponectin, adipsin, cathepsin S, chemerin, hepatic growth factor, interferon‐γ‐inducible protein‐10, leptin, macrophage chemoattractant protein‐1, macrophage migration inhibitory factor, nerve growth factor, retinol binding protein‐4, resistin, serum amyloid A1, tissue inhibitor of metalloproteinase‐1 and thrombopoietin using a microbead‐based Luminex assay. Area under the curves (AUC) were calculated and compared. Plasma adiponectin levels were higher after an oral fat load compared to fasting at t = 2 h (950 ± 513 vs. ?1,881 ± 713 ng/ml) while the plasma levels for adipsin (?9 ± 5 vs. 16 ± 5 ng/ml), chemerin (?122 ± 35 vs. 13 ± 21 ng/ml), SAA‐1 (?391 ± 213 vs. 522 ± 173 ng/ml) and TPO (?335 ± 144 vs. 622 ± 216 ng/ml) were lower after an oral fat load compared to fasting. The baseline corrected AUC for IP‐10 was higher after fat load compared to fasting (median ?116 pg h/ml; IQR ?270 to 10 vs. ?21 pg h/ml; IQR ?136 to 418 (p = 0.047). In conclusion, in overweight male subjects with the metabolic syndrome, an oral fat load is accompanied with a modest anti‐inflammatory response of adipose tissue‐derived adipocytokines.