Nanowire encapsulation with polymer for electrical isolation and enhanced optical properties

Light management and electrical isolation are essential for the majority of optoelectronic nanowire (NW) devices.Here,we present a cost-effective technique,based on vapor-phase deposition of parylene-C and subsequent annealing,that provides conformal encapsulation,anti-reflective coating,improved optical properties,and electrical insulation for GaAs nanowires.The process presented allows facile encapsulation and insulation that is suitable for any nanowire structure.In particular,the parylene-C encapsulation functions as an efficient antireflection coating for the nanowires,with reflectivity down to ＜1％ in the visible spectrum.Furthermore,the parylene-C coating increases photoluminescence intensity,suggesting improved light guiding to the NWs.Finally,based on this process,a NW LED was fabricated,which showed good diode performance and a clear electroluminescence signal.We believe the process can expand the fabrication possibilities and improve the performance of optoelectronic nanowire devices.     

Compressing Two-Dimensional Routing Tables

We consider an algorithmic problem that arises in the context of routing tables used by Internet routers. The Internet addressing scheme is hierarchical, where a group of hosts are identified by a prefix that is common to all the hosts in that group. Each host machine has a unique 32-bit address. Thus, all traffic between a source group s and a destination group d can be routed along a particular route c by maintaining a routing entry (s, d, c) at all intermediate routers, where s and d are binary bit strings. Many different routing tables can achieve the same routing behavior. In this paper we show how to compute the most compact routing table. In particular, we consider the following optimization problem: given a routing table D with N entries of the form (s, d, c) , determine a conflict-free routing table with fewest entries that has the same routing behavior as D. If the source and destination fields have up to w bits, and there are at most K different route values, then our algorithm runs in worst-case time O( NK w2) .     

The Role of Melodic and Temporal Cues in Perceiving Musical Meter.

A number of different cues allow listeners to perceive musical meter. Three experiments examined effects of melodic and temporal accents on perceived meter in excerpts from folk songs scored in 6/8 or 3/4 meter. Participants matched excerpts with 1 of 2 metrical drum accompaniments. Melodic accents included contour change, melodic leaps, registral extreme, melodic repetition, and harmonic rhythm. Two experiments with isochronous melodies showed that contour change and melodic repetition predicted judgments. For longer melodies in the 2nd experiment, variables predicted judgments best at the beginning of excerpts. The final experiment, with rhythmically varied melodies, showed that temporal accents, tempo, and contour change were the strongest predictors of meter. The authors' findings suggest that listeners combine multiple melodic and temporal features to perceive musical meter. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contracting With Uncertain Level Of Trust

The paper investigates the impact of trust on market efficiency and bilateral contracts. We prove that a market in which agents are trusted to the degree they deserve to be trusted is as efficient as a market with complete trustworthiness. In other words, complete trustworthiness is not a necessary condition for market efficiency. We prove that distrust could significantly reduce market efficiency, and we show how to solve the problem by using appropriately designed multiagent contracts. The problem of trust is studied in the context of a bilateral negotiation game between a buyer and a seller. It is shown that if the seller's trust equals the buyer's trustworthiness, then the social welfare, the amount of trade, and the agents' utility functions are maximized. The paper also studies the efficiency of advance payment contracts as a tool for improving trustworthiness. It is proved that advance payment contracts maximize the social welfare and the amount of trade. Finally, the paper studies the problem of how to make agents truthfully reveal their level of trustworthiness. An incentive–compatible contract is defined, in which agents do not benefit from lying about their trustworthiness. The analysis and the solutions proposed in this paper could help agent designers avoid many market failures and produce efficient interaction mechanisms.     

Acrylamide levels in Finnish foodstuffs analysed with liquid chromatography tandem mass spectrometry

Sample clean-up and HPLC with tandem mass spectrometric detection (LC-MS/MS) was validated for the routine analysis of acrylamide in various foodstuffs. The method used proved to be reliable and the detection limit for routine monitoring was sensitive enough for foods and drinks (38 microg/kg for foods and 5 microg/L for drinks). The RSDs for repeatability and day-to-day variation were below 15% in all food matrices. Two hundred and one samples which included more than 30 different types of food and foods manufactured and prepared in various ways were analysed. The main types of food analysed were potato and cereal-based foods, processed foods (pizza, minced beef meat, meat balls, chicken nuggets, potato-ham casserole and fried bacon) and coffee. Acrylamide was detected at levels, ranging from nondetectable to 1480 microg/kg level in solid food, with crisp bread exhibiting the highest levels. In drinks, the highest value (29 microg/L) was found in regular coffee drinks.     

Biogenic amines in cold-smoked fish fermented with lactic acid bacteria

 It has been proved in previous studies that fish can be fermented by lactic acid bacteria (LAB). Added glucose must be at concentrations of almost 1% to reduce the pH to <5.3, a level which corresponds to the safe pH values for meat products. Because some LAB and some contaminating microbes form biogenic amines, this study was conducted to examine the possible formation of biogenic amines during the fish fermentation process. Other parameters under study were sensory quality, pH value, titrated acid content, weight loss, a _w value, redox potential and microbiological counts. Three groups of fish (rainbow trout) with three different LAB inocula and a group without any inoculum were made. The fermentation of the products made with LAB succeeded. The products were sensorially accepted, the inoculated LAB grew to >8 log cfu/g, the pH reduced to 5.0–5.3 and a _w to 0.927 and the pseudomonads, the predominant flora of fish raw material, disappeared. The fish raw material and the products contained low amounts of biogenic amines with one exception: cadaverine, histamine and tyramine increased in all product groups in one experimental series (II) out of three. The highest concentrations of these amines were in the control products without any LAB inoculation. The LAB used and the contaminants isolated from the products were unable to produce cadaverine, histamine or tyramine. The appearance of these amines could therefore be caused by the non-isolated contaminants of fish raw material. Received: 18 June 1999     

Rigorous and approximate analysis of metallic gratings in soft X-ray and EUV regions

Abstract

In deep ultraviolet and soft X-ray regions the complex refractive indices of metals differ substantially from their values in the visible region of the spectrum. The implications of this fact are analysed for metallic gratings illuminated by electromagnetic fields with wavelengths ranging from soft X‐rays to near infrared, concentrating on short wavelengths. In particular, we study metal-stripe gratings (linear polarizers for visible light) by rigorous diffraction theory to determine the short-wavelength region in which a combination of the geometrical thin-element approximation and the theory of single-layer films can be applied. Then we study inductive grid filters for protection of X-ray detectors from infrared radiation in space applications.     

A Self-Calibrated Pipeline ADC with 200 MHz IF-Sampling Frontend

A 13-bit, 50-MS/s pipeline ADC with IF-sampling capability is presented. A high sampling linearity is obtained through the use of bootstrapped switches. A digital self-calibration algorithm with modified capacitor measurement scheme is employed to improve the accuracy of the first two pipeline stages. The prototype, implemented with a 0.35-m BiCMOS (SiGe) technology, shows a 76.5-dB SFDR at a 194.2-MHz signal frequency and dissipates 715 mW power from a 2.9-V supply.     

Simulation of light propagation by local spherical interface approximation

A new local elementary interface approximation is introduced for the modeling of wave propagation through interfaces between homogeneous media. The incident wave and the surface profile are approximated locally by a spherical wave and a spherical surface, respectively. The wave field travels through the modulated structure according to the laws of geometrical optics, being refracted by the surface and propagating to the output plane locally as a geometric spherical wave. Diffraction theory is applied to propagate the field from the output plane onwards. We provide comparisons of the method with the thin-element approximation, the local plane-wave and interface approach, and rigorous diffraction theory using a sinusoidal surface-relief grating as an example. We illustrate the power of the new method by applying it to the analysis of a diffractive beam splitter.     

High-level parameterizable area estimation modeling for ASIC designs

Architectural design space exploration and early area budgeting for ASIC and IP block development require accurate high level gate count estimation methods without requiring the hardware being fully specified. The proposed method uses hierarchical and parameterizable models requiring minimal amount of information about the implementation technology to meet this goal. The modeling process flow is to: (1) create a block diagram of the design, (2) create a model for each block, and (3) sum up estimates of all sub-blocks by supplying the correct parameters to each sub-model. We discuss the model creation for a few parameterized library blocks as well as three communication blocks and a processor core from real IC projects ranging from 22 to 250 kgates. The average relative estimation error of the proposed method for the library blocks is 3.2% and for the real world examples 4.0%. The best application of this method is early in the design phase when different implementation architectures are compared.