Quantum cryptography

Though most people think they are science fiction, quantum cryptography systems are now operational, with prototypes protecting Internet traffic across metropolitan areas. These systems are so novel that we can consider quantum cryptography, or more properly, quantum key distribution (QKD), as the third and final insight to transform cryptography in the 20th century.     

Competency-Based Behavior Consultation Training: An Evaluation of Consultant Outcomes, Treatment Effects, and Consumer Satisfaction.

Assessments of consultants, clients, and consumer satisfaction were used to examine the effects of a competency-based consultation training program conducted over 4 years. Using a multiple-baseline framework to assess training effects on consultants and single-case study designs to evaluate changes in client behavior, a number of significant results were found. As predicted, consultants (N=24) significantly increased their consultation skills and knowledge, but with no change in attitudes toward behavioral intervention techniques. Supervised consultation with preschool teachers and parents resulted in a range of behavior change in clients (N=39), with an overall effect size of 0.51. Consumers reported a high level of satisfaction with training and consultation services. Results of a long-term follow-up with consultants indicated positive views and use of consultation. The discussion focuses on these results, and implications for consultation training and future research directions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Three-dimensional reconstruction from images of tilted specimens: the paramyosin filament

The three-dimensional structure of the paramyosin filament has been reconstructed from images obtained when the specimen is tilted at different angles about its long axis. The micrographs were correlated spatially using gold marker beads and digitized. The different views contained in each micrograph were combined using a computational technique involving Fouri***er transforms and the resulting three-dimensional images are presented as various sets of serial sections. The results confirm that the Bear-Selby (1956) net can be seen at all levels in the specimen.     

The seafood supply chain from a fraudulent perspective

Food fraud is an intentional act for economic gain. It poses a risk to food integrity, the economy, public health and consumers’ ethics. Seafood is one commodity which has endured extensive fraudulent activity owing to its increasing consumer demand, resource limitations, high value and complex supply chains. It is essential that these fraudulent opportunities are revealed, the risk is evaluated and countermeasures for mitigation are assigned. This can be achieved through mapping of the seafood supply chains and identifying the vulnerability analysis critical control points (VACCP), which can be exposed, infiltrated and exploited for fraudulent activity. This research systematically maps the seafood supply chain for three key commodities: finfish, shellfish and crustaceans in the United Kingdom. Each chain is comprised of multiple stakeholders across numerous countries producing a diverse range of products distributed globally. For each supply chain the prospect of fraud, with reference to species substitution, fishery substitution, illegal, unreported and unregulated substitution, species adulteration, chain of custody abuse, catch method fraud, undeclared product extension, modern day slavery and animal welfare, has been identified and evaluated. This mapping of the fraudulent opportunities within the supply chains provides a foundation to rank known and emerging risks and to develop a proactive mitigation plan which assigns control measures and responsibility where vulnerabilities exist. Further intelligence gathering and management of VACCPs of the seafood supply chains may deter currently unknown or unexposed fraudulent opportunities.     

Comparing GC–MS,HPLC and H NMR analysis of beef longissimus dorsi tissue extracts to determine the effect of suspension technique and ageing

Beef longissimus dorsi muscle samples matured over a 21 day period were analysed using three different analytical techniques; ¹H NMR, GC–MS and HPLC. The data from the three experimental techniques were correlated with each other to determine if the results were statistically similar to each other. From our analysis we determined that the metabolites measured using ¹H NMR were statistically similar to the compounds quantified using the chromatography techniques (p < 0.001). In addition, using PCA, we were able to show that different metabolites, measured using the various analytical techniques produced very similar scores and loadings plots for all the analysis and extraction techniques undertaken across the 21 day time domain. Using a combination of these three different techniques provides a unique and holistic insight into the biochemistry behind the conversion of muscle to meat which would not be possible using any single technique alone.     

Atomistic Origin of the Enhanced Crystallization Speed and n‐Type Conductivity in Bi‐doped Ge‐Sb‐Te Phase‐Change Materials

Phase‐change alloys are the functional materials at the heart of an emerging digital‐storage technology. The GeTe‐Sb₂Te₃ pseudo‐binary systems, in particular the composition Ge₂Sb₂Te₅ (GST), are one of a handful of materials which meet the unique requirements of a stable amorphous phase, rapid amorphous‐to‐crystalline phase transition, and significant contrasts in optical and electrical properties between material states. The properties of GST can be optimized by doping with p‐block elements, of which Bi has interesting effects on the crystallization kinetics and electrical properties. A comprehensive simulational study of Bi‐doped GST is carried out, looking at trends in behavior and properties as a function of dopant concentration. The results reveal how Bi integrates into the host matrix, and provide insight into its enhancement of the crystallization speed. A straightforward explanation is proposed for the reversal of the charge‐carrier sign beyond a critical doping threshold. The effect of Bi on the optical properties of GST is also investigated. The microscopic insight from this study may assist in the future selection of dopants to optimize the phase‐change properties of GST, and also of other PCMs, and the general methods employed in this work should be applicable to the study of related materials, for example, doped chalcogenide glasses.     

The Variety of Scale

It is a truism that the essential qualities of a work of architecture cannot, since architecture is a visual art, be fully conveyed in words. No one would seriously maintain that this absolves those whose business it is to write or talk about architecture from the obligation to use words with some regard for exactness. Yet all too often we behave as if it did; certain words are bandied about as if all were agreed as to what they meant at any time, whereas in fact they may mean different things at different times, and even different things to different people at one time. Cecil Elliott here takes up the case of one such word, a small but much-abused one, isolating four distinct phenomena which it can denote in an architectural context and pursuing his inquiry beyond the realm of semantics to consider their practical implications for the designer.     

Electrical characteristics of high dielectric constant BCTZ thin films

Abstract

High dielectric constant Ba_0.96Ca_0.04Ti_0.84Zr_0.16O₃ (BCTZ) thin films were deposited on Pt/Ti/SiO₂/Si substrates by spin on metal-organic decomposition (MOD) technique. Undoped and 0.4% Mg-doped BCTZ thin films were annealed in the temperature range from 600 to 900 °C for 1 hour in oxygen environment. The crystal structure of BCTZ thin films was analyzed by X-ray diffraction. The electrical properties of BCTZ thin films were investigated by capacitance—voltage (C—V) characteristics. Also, the electrical properties of these films were compared in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications.     

Chalcogenide Phase-Change Materials: Past and Future

Phase-change (PC), nonvolatile memory (NVM) materials, such as Ge₂Sb₂Te₅ (GST), encode stored digital binary data as structural changes in the material. Reversible, ultrafast (nanosecond) transformations between metastable semiconducting/nonreflective amorphous and near-metallic/reflective crystalline states occur as a result of Joule heating, caused by applied voltage/laser write pulses, in electronic/optical NVMs, respectively. The canonical PCM, GST, was originally discovered and developed for optical NVM; although it also works as an electronic NVM (phase-change random-access memory, PCRAM) material, nevertheless it is not optimal in this role. In this contribution, I will discuss the effects of “doping” (or chemical modification) of GST, with elements such as nitrogen or first-row transition metals, to improve PC characteristics, such as crystal grain size, and optical-reflectivity contrast for optical NVM, and to introduce additional PC functionality, for example, magnetism for electronic NVM, respectively. These studies have been carried out by ab initio molecular-dynamics (AIMD) simulations, in which new compositions of doped PCMs have been obtained by a process of in silico materials discovery. I will also describe a strategy to decrease the rate-limiting crystallization time of PCMs, which does not also decrease long-term data retention in the amorphous state (i.e., deleterious spontaneous crystallization), by means of the use of “priming” prepulses. AIMD simulations indicate the structural-ordering origin of this priming behavior. In this way, we have reduced the crystallization time of GST, from ~10 ns down to ~500 ps, well below the critical switching time of ~1 ns needed to replace volatile Si-based CMOS DRAM by an NVM-equivalent, so-called “universal memory”. Finally, I will outline very recent work which demonstrates that GST PCM cells can also be used to perform “in-memory” Boolean logic operations, thereby combining memory and processing operations in the same cell.