Microwave method for high-frequency properties of graphene

Graphene is a remarkable material, which is yet to make the transition from unique laboratory phenomenon to useful industrial material. One missing element in the development process is a quick method of quality control of the electrical properties of graphene which may be applied in, or close to, the graphene growth process on an industrial scale. In this study, the authors describe a non-contact method using microwave resonance which potentially solves this problem. They describe the technique, consider its limitations and accuracy and suggest how the method may have future take up.UK NMS Programme, the EU EMRP project ‘GraphOhm’ and ‘MetNEMS’. The EMRP (European Metrology Research Programme

Direct measurement of penetration length in ultra-thin and/or mesoscopic superconducting structures

We describe a method for direct measurement of the magnetic penetration length in thin (10 - 100 nm) superconducting structures having overall dimensions in the range 1 to 100 micrometers. The method is applicable for broadband magnetic fields from dc to MHz frequencies.Comment: Accepted by Journal of Applied P:hysics (Jun 2006).5 pages, 5 figure

Do Blogs Help Students to Learn?: Case Study

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Fabrication and analogue applications of nanoSQUIDs using Dayem bridge junctions

We report here recent work at the U.K. National Physical Laboratory on developing nanoscale SQUIDs using Dayem bridge Josephson junctions. The advantages are simplicity of fabrication, exceptional low-noise performance, toward the quantum limit, and a range of novel applications. Focused ion beam patterned Nb SQUID, possessing exceptionally low noise (∼200 nΦ0/Hz1/2 above 1 kHz), and operating above 4.2 K can be applied to measurement of nanoscale magnetic objects or coupled to nanoelectromechanical resonators, as well as single particle detection of photons, protons, and ions. The limited operating temperature range may be extended by exposing the Dayem bridges to carefully controlled ion beam implantation, leading to nonreversible changes in junction transition temperature.The work reported here was supported in part by the EMRP projects ‘MetNEMS’ NEW-08 and ‘BioQUART’SIB-06. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union

A Randomized Depression Prevention Trial Comparing Interpersonal Psychotherapy—Adolescent Skills Training To Group Counseling In Schools

Given the rise in depression disorders in adolescence, it is important to develop and study depression prevention programs for this age group. The current study examined the efficacy of Interpersonal Psychotherapy-Adolescent Skills Training (IPT-AST), a group prevention program for adolescent depression, in comparison to group programs that are typically delivered in school settings. In this indicated prevention trial, 186 adolescents with elevated depression symptoms were randomized to receive IPT-AST delivered by research staff or group counseling (GC) delivered by school counselors. Hierarchical linear modeling examined differences in rates of change in depressive symptoms and overall functioning from baseline to the 6-month follow-up assessment. Cox regression compared rates of depression diagnoses. Adolescents in IPT-AST showed significantly greater improvements in self-reported depressive symptoms and evaluator-rated overall functioning than GC adolescents from baseline to the 6-month follow-up. However, there were no significant differences between the two conditions in onset of depression diagnoses. Although both intervention conditions demonstrated significant improvements in depressive symptoms and overall functioning, results indicate that IPT-AST has modest benefits over groups run by school counselors which were matched on frequency and duration of sessions. In particular, IPT-AST outperformed GC in reduction of depressive symptoms and improvements in overall functioning. These findings point to the clinical utility of this depression prevention program, at least in the short-term. Additional follow-up is needed to determine the long-term effects of IPT-AST, relative to GC, particularly in preventing depression onset

Assessing the impact of non-random measurement error on inference : a sensitivity analysis approach

Many commonly used data sources in the social sciences suffer from non-random measurement error, understood as mis-measurement of a variable that is systematically related to another variable. We argue that studies relying on potentially suspect data should take the threat this poses to inference seriously and address it routinely in a principled manner. In this article, we aid researchers in this task by introducing a sensitivity analysis approach to non-random measurement error. The method can be used for any type of data or statistical model, is simple to execute, and straightforward to communicate. This makes it possible for researchers to routinely report the robustness of their inference to the presence of non-random measurement error. We demonstrate the sensitivity analysis approach by applying it to two recent studies

Novel methods of fabrication and metrology of superconducting nanostructures

As metrology extends toward the nanoscale, a number of potential applications and new challenges arise. By combining photolithography with focused ion beam and/or electron beam methods, superconducting quantum interference devices (SQUIDs) with loop dimensions down to 200 nm and superconducting bridge dimensions of the order 80 nm have been produced. These SQUIDs have a range of potential applications. As an illustration, we describe a method for characterizing the effective area and the magnetic penetration depth of a structured superconducting thin film in the extreme limit, where the superconducting penetration depth $lambda$ is much greater than the film thickness and is comparable with the lateral dimensions of the device