MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical-chemical vapor deposition

The MgB2 coated superconducting tapes have been fabricated on textured Cu (0 0 1) and polycrystalline Hastelloy tapes using coated conductor technique, which has been developed for the second generation high temperature superconducting wires. The MgB2/Cu tapes were fabricated over a wide temperature range of 460-520 {\deg}C by using hybrid physical-chemical vapor deposition (HPCVD) technique. The tapes exhibited the critical temperatures (Tc) ranging between 36 and 38 K with superconducting transition width (\DeltaTc) of about 0.3-0.6 K. The highest critical current density (Jc) of 1.34 \times 105 A/cm2 at 5 K under 3 T is obtained for the MgB2/Cu tape grown at 460^{\circ}C. To further improve the flux pinning property of MgB2 tapes, SiC is coated as an impurity layer on the Cu tape. In contrast to pure MgB2/Cu tapes, the MgB2 on SiC-coated Cu tapes exhibited opposite trend in the dependence of Jc with growth temperature. The improved flux pinning by the additional defects created by SiC-impurity layer along with the MgB2 grain boundaries lead to strong improvement in Jc for the MgB2/SiC/Cu tapes. The MgB2/Hastelloy superconducting tapes fabricated at a temperature of 520 {\deg}C showed the critical temperatures ranging between 38.5 and 39.6 K. We obtained much higher Jc values over the wide field range for MgB2/Hastelloy tapes than the previously reported data on other metallic substrates, such as Cu, SS, and Nb. The Jc values of Jc(20 K, 0 T) \sim5.8 \times 106 A/cm2 and Jc(20 K, 1.5 T) ~2.4 \times 105 A/cm2 is obtained for the 2-\mum-thick MgB2/Hastelloy tape. This paper will review the merits of coated conductor approach along with the HPCVD technique to fabricate MgB2 conductors with high Tc and Jc values which are useful for large scale applications.Comment: 17 pages, 12 figures, accepted for publication in Current Applied Physics as a review articl

The On-orbit Calibrations for the Fermi Large Area Telescope

The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope began its on--orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Self-emulsifying therapeutic system: a potential approach for delivery of lipophilic drugs

Self-emulsifying therapeutic system (SETs) provide an effective and intelligent solution to the various issues related to the formulation of hydrophobic drugs with limited solubility in gastrointestinal fluid. Although the potential utility of SETs is well known, only in recent years has a mechanistic understanding of the impact of these systems on drug disposition emerged. These in situ emulsion-forming systems have a high stability when incorporated in various dosage forms. SETs are being looked upon as systems which can overcome the problems associated with delivery of poorly water soluble drugs. An in-depth knowledge about lipids and surfactants that can contribute to these systems, criterion for their selection and the proportion in which they can be used, represent some crucial factors determining the in vivo performance of these systems. This article presents a comprehensive account of various types of self-emulsifying formulations with emphasis on their composition and examples of currently marketed preparations.O sistema terapêutico auto-emulsionante (SETs) fornece solução eficaz e inteligente para os vários problemas relativos à formulação de fármacos hidrofóbicos com solubilidade limitada no fluido gastrintestinal. Embora a utilidade potencial dos SETs seja bem conhecida, só recentemente se compreendeu, mecanisticamente,o impacto desses sistemas na disposição de fármacos. Estes sistemas de formação de emulsão in situ têm alta estabilidade, quando incorporados em várias formas de dosagem. Os SETs têm sido considerados como sistemas que podem resolver problemas associados à liberação de fármacos pouco solúveis em água. O conhecimento profundo dos lipídios e tensoativos que podem ser utilizados para estes sistemas e o critério para a sua seleção e proporção na qual eles são utilizados são alguns dos fatores cruciais que determinam o desempenho do sistema in vivo. Este artigo apresenta o relato abrangente de vários tipos de formulações auto-emulsificantes, com ênfase em sua composição e exemplos das preparações que são correntemente comercializadas

CMOS-compatible polarization rotator design based on asymmetrical periodic loaded waveguide structure

Silicon-on-insulator (SOI) technology has been a promising platform for photonic applications. However, the high index-contrast between silicon and the top cladding (SiO2 or air) of the SOI waveguides makes the modal birefringence hard to control. Consequently, SOI based photonics integrated circuits (PICs) are in general highly polarization-sensitive, making polarization management important. In this paper, a polarization rotator (PR) design on the 220 nm SOI platform is demonstrated through numerical simulations and experiments. The demonstrated PR design is based on asymmetrical periodic loaded waveguide structures. The demonstrated design features compact device footprint and can be fabricated by CMOS compatible process. In addition, no special cladding is required to break the vertical symmetry of the waveguide. The design has shown promising performance over the C-band wavelengths (1530 nm-1565 nm) by simulations. However, the fabrication requirements are stringent for the design, thus the performance of the fabricated devices are limited by the current fabrication technology

SOI polarization rotators with asymmetrical periodic perturbations

We demonstrate the design and experimental results of two polarization rotator designs based on asymmetrical periodic loaded SOI waveguides. The devices feature CMOS compatible fabrication process, with compact footprints (<20 μm in length). Both designs operate within a 25 nm wavelengths range

Compact polarization rotator design based on asymmetrical periodic loaded SOI waveguides

We propose a polarization rotator design based on an asymmetrical periodic loaded waveguides on SOI platforms. The device features high conversion efficiency. The fabrication is CMOS compatible with a two-step lithography etching

Deliberate Robbery, or the Calculating Samaritan

. In this paper we introduce the deliberating robber, an example of reasoning about preferences in a logic of desires. We show that two defeasible reasoning schemes proposed in qualitative decision theory derive counterintuitive consequences. 1 Introduction In the usual approaches to planning in AI, a planning agent is provided with a description of some state of affairs, a goal state, and charged with the task of discovering (or performing) some sequence of actions to achieve that goal. Contextsensitive goals are provided for situations in which the agent encounters goals that it cannot achieve, for example when its objectives can be satisfied to varying degrees, such as time taken to fill a tank or amount of fluid spilled. The desirability aspect of context-sensitive goals is formalized with preferencebased or utilitarian semantics, which are provided by decision theory [8, 10, 3]. 3 Besides expressing the desirability of a state, adopting a goal represents some commitment to purs..

Contextual Deontic Logic

In this article we propose contextual deontic logic (CDL). Contextual obligations are written as O(ffjfinfl), and are to be read as `ff should be the case if fi is the case, unless fl is the case&apos;. The unless clause is analogous to the justification in Reiter&apos;s default rules. We show how contextual obligations can be used to solve certain aspects of contrary-to-duty paradoxes of dyadic deontic logic

Prohairetic Deontic Logic and Qualitative Decision Theory

In this paper we introduce Prohairetic Deontic Logic, a preference-based dyadic deontic logic. An obligation `ff should be (done) if fi is (done)&apos; is true if (1) no :ff fi is preferred to an fffi and (2) the preferred fi are ff. We show that this mixed representation solves several problems of deontic logic. Moreover, we discuss the relation between preferencebased deontic logic and qualitative decision theory. Introduction Deontic logic is a modal logic developed in philosophical logic. Absolute and conditional obligations are represented by the modal formulas Off and O(ff j fi), where the latter is read as `ff ought to be (done) if fi is (done).&apos; The development of preference-based deontic logic is plagued by the following three (related) problems: Strong preference problem. Preferences for ff 1 and ff 2 conflict for ff 1 :ff 2 and :ff 1 ff 2 . Contrary-to-duty problem. A contrary-to-duty obligation is an obligation that refers to a sub-ideal situation. Reasoning structures lik..