Laboratory accreditation in the UK

Two complementary national laboratory accreditation schemes are run by the National Physical Laboratory (NPL) to provide official recognition of competent British laboratories and an assurance of quality to their customers. The first of these, the British Calibration Service (BCS), was set up in 1966 to accredit laboratories to calibrate instruments, gauges and reference materials. In 1981 the National Testing Laboratory Accreditation Scheme (NATLAS) was formed to extend the service to all kinds of testing. Both BCS and NATLAS form an integral part of the UK national measurement system and were combined to form the National Measurement Accreditation Service on 1 October 1985.     

Questionnaire development: an examination of the Nordic Musculoskeletal questionnaire

This paper describes the outcome of user trials of the Nordic Musculoskeletal Questionnaire which encompassed the views of the following groups: data entry clerks, technical staff, administrative clerks and 481 subjects employed in 10 supermarkets. A significant number of improvements was identified, especially concerning its wording, layout and administration. This has led to a standardized version being produced for use in studying the prevalence of reported symptoms in many types of occupational groups.     

Precession technique and electron diffractometry as new tools for crystal structure analysis and chemical bonding determination

We have developed a new fast electron diffractometer working with high dynamic range and linearity for crystal structure determinations. Electron diffraction (ED) patterns can be scanned serially in front of a Faraday cage detector; the total measurement time for several hundred ED reflections can be tens of seconds having high statistical accuracy for all measured intensities (1-2%). This new tool can be installed to any type of TEM without any column modification and is linked to a specially developed electron beam precession "Spinning Star" system. Precession of the electron beam (Vincent-Midgley technique) reduces dynamical effects allowing also use of accurate intensities for crystal structure analysis. We describe the technical characteristics of this new tool together with the first experimental results. Accurate measurement of electron diffraction intensities by electron diffractometer opens new possibilities not only for revealing unknown structures, but also for electrostatic potential determination and chemical bonding investigation. As an example, we present detailed atomic bonding information of CaF(2) as revealed for the first time by precise electron diffractometry.     

Ultra-Thin Si<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Dislocation Blocking Layers for Ge/Strained Si CMOS Devices

We demonstrate ultra-thin (<150 nm) Si_1−x Ge _x dislocation blocking layers on Si substrates used for the fabrication of tensile-strained Si N channel metal oxide semiconductor (NMOS) and Ge P channel metal oxide semiconductor (PMOS) devices. These layers were grown using ultra high vacuum chemical vapor deposition (UHVCVD). The Ge mole fraction was varied in rapid, but distinct steps during the epitaxial layer growth. This results in several Si_1−x Ge _x interfaces in the epitaxially grown material with significant strain fields at these interfaces. The strain fields enable a dislocation blocking mechanism at the Si_1−x Ge _x interfaces on which we were able to deposit very smooth, atomically flat, tensile-strained Si and relaxed Ge layers for the fabrication of high mobility N and P channel metal oxide semiconductor (MOS) devices, respectively. Both N and P channel metal oxide semiconductor field effect transister (MOSFETs) were successfully fabricated using high-k dielectric and metal gates on these layers, demonstrating that this technique of using ultra-thin dislocation blocking layers might be ideal for incorporating high mobility channel materials in a conventional CMOS process.     

CD28 can promote T cell survival through a phosphatidylinositol 3-kinase-independent mechanism

Phosphatidylinositol 3(PI3)-kinase is implicated in various biological responses, including protection from apoptosis, although its role in antigen-induced T cell death and the molecular effectors it triggers remains ill-defined. Here, we investigated the role of PI3-kinase activity in the prevention of T cell receptor/CD3-induced cell death by CD28. PI3-kinase inhibitors blocked the up-regulation of Bcl-X(L) by CD28, without impairing the prevention of T cell receptor/CD3-triggered apoptosis by CD28, hence showing the existence of a cell-survival pathway independent of PI3-kinase activity and up-regulation of Bcl-X(L). Instead, we show that up-regulation of FasL which is instrumental in CD3-induced apoptosis was prevented upon CD28 co-stimulation. These results indicate that PI3-kinase couples CD28 to Bcl-X(L) up-regulation and provide a molecular basis for the role of CD28 in cell survival through a PI3-kinase-independent mechanism including FasL down-regulation.     

Amino-terminal charge affects the periplasmic accumulation of recombinant heregulin/EGF hybrids exported using the Escherichia coli alkaline phosphatase signal sequence

An Escherichia coli expression system that exploits the bacterial alkaline phosphatase (PhoA) signal sequence to translocate recombinant human epidermal growth factor (hEGF) to the periplasm was used to evaluate how changes in the composition and sequence of amino acids near the PhoA-hEGF junction influence the periplasmic accumulation of recombinant protein. A series of chimeric structural genes was generated by in vitro replacement of hEGF sequence with analogous segments from the EGF-like domain of human heregulin (HRG), significantly altering the electrostatic character of the amino-terminal region of the mature protein. Quantitation of HRG/EGF protein in E. coli periplasmic extracts, by RP-HPLC, showed a fourfold decrease after one of two acidic residues located in the amino-terminal region of the mature hEGF, near the PhoA junction, was replaced. An additional threefold decrease was observed when the second acidic residue was replaced with a positively charged lysine. Further extension of the amino-terminal HRG sequence, beyond the first six residues, resulted in net neutralization of a more distant EGF acidic residue with no additional effect on protein yield. The importance of having a negatively charged group in the amino-terminal region of the mature protein was confirmed when insertion of an aspartic acid near the amino-terminus of two poorly expressed hybrid protein sequences resulted in a five- to eightfold increase in their recovery from the periplasm. This study demonstrates the importance of having negatively charged residues near the fusion junction of recombinant proteins expressed in E. coli using the PhoA signal sequence for protein export.     

Predicting student attitudes about racial diversity and gender equity.

[Correction Notice: An erratum for this article was reported in Vol 4(3) of Journal of Diversity in Higher Education (see record 2011-16523-001). There are two errors in Table 2 under the RWA heading and the Cog-gender heading. The necessary changes are provided in the erratum.] [Correction Notice: An erratum for this article was reported in Journal of Diversity in Higher Education on August 1 2011 (see record 2011-16523-001). There are two errors in Table 2. Under the RWA heading, the SDO row should have indicated a positive correlation of .266**, not -.266**. Under the Cog-gender heading, the SDO row should have indicated a negative correlation of -.438**, not .438**.] Factors related to attitudes about racial diversity and gender equity were examined in an ethnically diverse sample of 432 college students (167 European Americans, 83 African Americans, 81 Asian Americans, and 82 Hispanic Americans). In addition to variables of self-interest (i.e., ethnicity, gender, and political views), social ideology (i.e., social dominance orientation, right-wing authoritarianism) and personality traits (openness to experience) were uniquely predictive of attitudes about racial diversity and gender equity. Hierarchical regressions revealed that social dominance orientation most strongly predicted racial attitudes, while right-wing authoritarianism most strongly predicted gender attitudes. Implications for diversity education efforts related to prejudice reduction are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Optical communication and fiber design

Optical fiber has evolved from a not-so-transparent glass tube to an extraordinarily efficient transmission medium. It is now acknowledged as a central element of modern telecommunication being part of the whole optimization process to further improve transmission system performance and cost. In this paper, we briefly introduce transmission system optimization problematics as well as key fiber characteristics. We then review the elements of fiber design for optimized optical communication networks, including metropolitan, long and ultra-long haul applications and show how fibers have evolved over the last ten years to keep pace with more and more demanding requirement of transmission system.