Ultrafast Photo-Thermal Switching of Terahertz Spin Currents

Dissipationless and scattering-free spin-based terahertz electronics is the futuristic technology for energy-efficient information processing. Femtosecond light pulse provides an ideal pathway for exciting the ferromagnet (FM) out-of-equilibrium, causing ultrafast demagnetization and superdiffusive spin transport at sub-picosecond timescale, giving rise to transient terahertz radiation. Concomitantly, light pulses also deposit thermal energy at short timescales, suggesting the possibility of abrupt change in magnetic anisotropy of the FM that could cause ultrafast photo-thermal switching (PTS) of terahertz spin currents. Here, a single light pulse induced PTS of the terahertz spin current manifested through the phase reversal of the emitted terahertz photons is demonstrated. The switching of the transient spin current is due to the reversal of the magnetization state across the energy barrier of the FM layer. This demonstration opens a new paradigm for on-chip spintronic devices enabling ultralow-power hybrid electronics and photonics fueled by the interplay of charge, spin, thermal, and optical signals.     

Painterly rendering techniques: a state‐of‐the‐art review of current approaches

In this publication we will look at the different methods presented over the past few decades which attempt to recreate digital paintings. While previous surveys concentrate on the broader subject of non‐photorealistic rendering, the focus of this paper is firmly placed on painterly rendering techniques. We compare different methods used to produce different output painting styles such as abstract, colour pencil, watercolour, oriental, oil and pastel. Whereas some methods demand a high level of interaction using a skilled artist, others require simple parameters provided by a user with little or no artistic experience. Many methods attempt to provide more automation with the use of varying forms of reference data. This reference data can range from still photographs, video, 3D polygonal meshes or even 3D point clouds. The techniques presented here endeavour to provide tools and styles that are not traditionally available to an artist. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance analysis of pseudo 4-phase dual-rail asynchronous protocol

This article presents the performance analysis of novel pseudo 4-phase dual-rail protocol with self-reset and multiple-reset logic for high speed asynchronous applications. The self-reset logic eliminates the need for separate empty phase and hence reduces the number of transitions at the input and the output. The multiple-reset logic reduces the reset phase and hence increases the throughput. The performance of the pseudo 4-phase dual-rail protocol is compared with the existing 4-phase dual-rail protocol by implementing 8-bit and 16-bit asynchronously pipelined carry look ahead adders (CLA) in 0.35?µm technology. The time period decreases up to 32.58% and 35.93% respectively, the reset phase reduces up to 66.39% and 76.18%, respectively, and the operating frequency increases up to 48.4% and 56.2%, respectively, for 8- and 16-bit CLA adders with the pseudo 4-phase dual-rail protocol compared to the conventional 4-phase dual-rail protocol at the cost of increase in area of 8.8% and 3.3%, respectively. The delay-power product in ns-mW of the 8- and 16-bit CLAs is reduced at the maximum of 11.29% and 23.74%, respectively, with the pseudo 4-phase dual-rail protocol compared to the conventional 4-phase dual-rail protocol. The pseudo 4-phase dual-rail protocol is suitable for interfacing with synchronous environments.     

Daily smoking patterns, their determinants, and implications for quitting.

In this article, the authors examine daily temporal patterns of smoking in relation to environmental restrictions on smoking and cessation outcomes. Time-series methods were used for analyzing cycles in 351 smokers who monitored their smoking in real time for 2 weeks. The waking day was divided into 8 "bins" of approximately 2 hr, cigarette counts were tallied for each bin, and temporal patterns of smoking and restriction were analyzed. Cluster analyses of smoking patterns by time of day resulted in 4 clusters: daily decline (n = 30; 9%), morning high (n = 43; 12%), flatline (n = 247; 70%), and daily dip-evening incline (n = 31; 9%). Clusters differed in baseline demographic, smoking, and psychosocial variables. Results suggest that smoking behavior can be characterized by regular patterns of smoking frequency during the waking day: Smoking in the flatline cluster was within ±0.5 standard deviation at all times. For the other clusters, smoking was high in the morning (daily dip-evening incline: +1.7 standard deviations; morning high: +2.8 standard deviations; daily decline: +1.7 standard deviations); moderate (morning high: -0.8 standard deviations; daily decline: +0.3 standard deviations) or low (daily dip-evening incline: -1.0 standard deviations) midday; and high (daily dip-evening incline: +2.0 standard deviations), moderate (morning high: +0.5 standard deviations), or low (daily decline: -1.5 standard deviations) in the evening. Daily smoking patterns were related to environmental smoking restrictions, but the strength of this relationship differed among clusters and by time of day. Clusters differed in lapse risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Silicification and Biosilicification. Part 4. Effect of Template Size on the Formation of Silica

Silicification at neutral pH and under ambient conditions is of growing interest due to its close relationship with biosilicification. In diatoms biosilicification has been reported to occur at (or close to) neutral pH and it has been shown that protein molecules act as catalysts/templates/scaffolds for this elegant materials chemistry. In this investigation various catalysts/templates have been studied for their role in silicification in vitro. We have used functionalized C₆₀ fullerene, R5 (an important polypeptide from the amino acid sequence of a silaffin protein), poly-l-lysine (PLL) and two poly(allylamine hydrochloride) (PAH) samples having different molecular weights. An aqueous silica precursor was used and ordered silica structures were produced in each of the systems studied. The sizes of the silica structures appear to correlate with the size, in solution, of the templating/scaffolding agents. Biological systems exhibit hierarchical structures with remarkable control of morphologies over different length scales. The use of templating/scaffolding agents having different sizes and shapes is one possible paradigm for the production of such structures in vivo.     

Scattering from dielectric and metallic bodies using a high-order, Nystrom, multilevel fast mutipole algorithm

The multilevel fast multipole algorithm (MLFMA) is an established way to accelerate the solution of the integral equations governing scattering of electromagnetic waves. Another way is to use high-order methods, of which the locally corrected Nystrom (LCN) method is, perhaps, the best; it has been applied to metallic scatterers up to order 10. In this paper, the technique (MLFMA + LCN) is extended to handle mixed conducting/dielectric bodies. Results for coated circular and square cylinders, using orders up to 8, demonstrate the efficiency of the method.     

A detailed model for the decomposition of nitramines: RDX and HMX

A unified decomposition scheme for two very important cyclic nitramines used as primary explosives – RDX and HMX – has been constructed using ab initio Density Functional Theory (DFT) calculations. Molecular parameters such as vibrational frequencies and moments of inertia corresponding to the computed potential energy profile of unimolecular decomposition of these nitramines were then used to obtain the thermochemistry of all identified species and reaction rate constants of each individual channel. These primary decomposition reactions were then combined with: (i) important secondary reactions of the key reactive radical intermediates, such as CH₂NNO₂ (Methylene Nitramine MN), CH₂N, NO, NO₂, OH, etc.; (ii) existing nitramie reaction networks [33]. We have developed an improved mechanism for the detailed chemistry of nitramines which can be applied to combustion and detonation phenomena of this class of energetic materials. This revised version was published online in June 2006 with corrections to the Cover Date.     

Low Thermal Conductivity and High Thermoelectric Performance in In<Subscript>4</Subscript>Se<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript> with Phase-Separated Indium Inclusions

We report the thermoelectric properties of undoped hot-pressed In₄Se_3?x (x = 0.05). Stoichiometric imbalance due to selenium deficiency in In₄Se₃ was found to create a secondary phase of elemental indium in the host material. Heat treatment drove grain growth and increased the indium solubility in In₄Se₃. Indium-rich domains at grain surfaces/boundaries in untreated samples were found to redistribute inside the grains and their junctions after heat treatment. Due to enhanced phonon scattering by secondary phase of indium, very low values of thermal conductivity were observed for all samples, leading to a maximum thermoelectric figure of merit (zT) of 1.13 at 723 K along the hot-pressing direction for the heat-treated sample.     

Correlation development for effect of metal contaminants on the oxidation stability of Jatropha curcas biodiesel

The present paper deals with the study on the effect of metal contaminants on the oxidation stability of Jatropha curcas biodiesel (JCB). Taking pyrogallol as the most effective antioxidant based on the earlier work of the authors, JCB was mixed with different transition metals - Fe, Ni, Mn, Co and Cu in different concentrations. Induction period (IP) was measured using Rancimat method (EN 14112). Based on results, several correlations are developed for assessing the oxidation stability in terms of IP as a function of antioxidant and metal concentration. A comparison between the experimental IP values and those predicted by the correlation shows that about 95% of the predicted data points lie within ±10% deviation lines of the experimental results. This is the first study of its kind being reported showing the relationship of IP with antioxidant concentration and metal contaminants. The correlations developed can be used to predict the amount of antioxidants required to stabilize the JCB.     

l-Delay Input and Initial-State Reconstruction for Discrete-Time Linear Systems

Prior results on input reconstruction for multi-input, multi-output discrete-time linear systems are extended by defining l-delay input and initial-state observability. This property provides the foundation for reconstructing both unknown inputs and unknown initial conditions, and thus is a stronger notion than l-delay left invertibility, which allows input reconstruction only when the initial state is known. These properties are linked by the main result (Theorem 4), which states that a MIMO discrete-time linear system with at least as many outputs as inputs is l-delay input and initial-state observable if and only if it is l-delay left invertible and has no invariant zeros. In addition, we prove that the minimal delay for input and state reconstruction is identical to the minimal delay for left invertibility. When transmission zeros are present, we numerically demonstrate l-delay input and state reconstruction to show how the input-reconstruction error depends on the locations of the zeros. Specifically, minimum-phase zeros give rise to decaying input reconstruction error, nonminimum-phase zeros give rise to growing reconstruction error, and zeros on the unit circle give rise to persistent reconstruction error.