Crystallographic Aspects of the CDW Instabilities in NbSe3

Charge-density waves (CDW) in some quasi one-dimensional compounds can be depinned from the lattice by an external electric field. In the case of NbSe3, two CDW transitions have been reported with onset temperatures of 144 K and 59 K. From an analysis of the published low-temperature (LT) scanning tunneling microscopy (STM) images, which inherently allow the resolution of domain structures on the atomic scale, an alternative model of the CDW modulated structures in NbSe3 is proposed. In contrast to the existing model, where two incommensurate (IC) modes, q1 = (0,0.241,0) and q2 = (0.5,0.260,0.5) are selectively confined to two of three available structurally distinguished types of bi-capped trigonal prismatic columns, the alternative model [1,2] proceeds from the assumption that both columns of the same pair are alternatively modulated by the two modes, whose IC components add within experimental error into a commensurate value. The observed domains are formed as a result of the different bonding within and between the structural layers, separated by Van der Waals gaps, and of the ability of the two modes to be easily interchanged between two symmetry-related columns of the same type. This assumption is in accord with the published LT STM results, which confirm i.a. the presence of both IC modes above 59 K, where according to the previous model only the q1 contribution should be expected. A pair of two alternatively modulated columns of the same type represents the basic structural unit of the CDW ground state. The two modes can formally be replaced by a single inharmonic modulation, obtained by "beating" between the two IC modes.

A comprehensive laboratory-based program for classification of variants of uncertain significance in hereditary cancer genes

Genetic testing has the potential to guide the prevention and treatment of disease in a variety of settings, and recent technical advances have greatly increased our ability to acquire large amounts of genetic data. The interpretation of this data remains challenging, as the clinical significance of genetic variation detected in the laboratory is not always clear. Although regulatory agencies and professional societies provide some guidance regarding the classification, reporting, and long-term follow-up of variants, few protocols for the implementation of these guidelines have been described. Because the primary aim of clinical testing is to provide results to inform medical management, a variant classification program that offers timely, accurate, confident and cost-effective interpretation of variants should be an integral component of the laboratory process. Here we describe the components of our laboratory's current variant classification program (VCP), based on 20 years of experience and over one million samples tested, using the BRCA1/2 genes as a model. Our VCP has lowered the percentage of tests in which one or more BRCA1/2 variants of uncertain significance (VUSs) are detected to 2.1% in the absence of a pathogenic mutation, demonstrating how the coordinated application of resources toward classification and reclassification significantly impacts the clinical utility of testing.

Shaping the research experiences of graduate students using action research

BACKGROUND

Nursing research capacity is often not optimal in developing countries. Capacity building at the graduate nurse level presents an opportunity for improved research output. Students pursuing a research methods course at a nursing school in Jamaica expressed fear and anxiety towards the course. Action research was used to address this fear and improve learning outcomes.

OBJECTIVE

To determine attitudes towards research and to improve the experience of graduate students pursuing a research methods course at a nursing school in Jamaica.

METHODS

Students (n=44) registered in the Research Methods course of the MScN at a nursing school in Kingston, Jamaica for the academic year 2010/2011, were invited to participate. Each student was assigned a main supervisor and an alternate supervisor and all had equal access to the course leader and content. On completion of the course three focus group discussions of 10-14 students per group were conducted to determine how students felt about the course experience and their attitude towards the course.

RESULTS

Thirty-seven students (mean age of 41.4 ± 1.5 years; 94% female) participated in the exploratory course evaluation exercise. The participants reported that they entered research methods with feelings of apprehension and anxiety. However, these fears were allayed by a combination of factors including interest in students' welfare, affirmation of students, respect for and understanding of students' needs and resourcefulness, and the use of a panel of experts. Barriers included faculty's unrealistic expectations of students' research competencies and the limited time in which to learn and apply concepts. While students thought the course as challenging they felt more confident that they could be successful on completion of the course.

CONCLUSION

Significant improvement in attitudes to research was realized among graduate nursing students using action research at an urban school of nursing in Jamaica.

Mitochondrial protectant pramipexole prevents sex-specific long-term cognitive impairment from early anaesthesia exposure in rats

BACKGROUND

Exposure to general anaesthesia during critical stages of brain development results in long-lasting cognitive impairment. Co-administration of protective agents could minimize the detrimental effects of anaesthesia. Co-administration of R(+)pramipexole (PPX), a synthetic aminobenzothiazol derivative that restores mitochondrial integrity, prevents anaesthesia-induced mitochondrial and neuronal damage and prevents early development of cognitive impairment. Here, we determine the protective effects of PPX into late adulthood in male and female rats.

METHODS

Postnatal day 7 rats of both sexes were exposed to mock anaesthesia or combined midazolam, nitrous oxide, and isoflurane anaesthesia for 6 h with or without PPX. Cognitive abilities were assessed between 5 and 7 months of age using Morris water maze spatial navigation tasks.

RESULTS

Examination of spatial reference memory revealed that female, but not male, neonatal rats exposed to anaesthesia showed slowing of acquisition rates, which was significantly improved with PPX treatment. Examination of memory retention revealed that both male and female anaesthesia-treated rats have impaired memory retention performance compared with sham controls. Co-treatment with PPX resulted in improvement in memory retention in both sexes.

CONCLUSION

PPX provides long-lasting protection against cognitive impairment known to occur when very young animals are exposed to anaesthesia during the peak of brain development. Anaesthesia-induced cognitive impairment appears to be sex-specific with females being more vulnerable than males, suggesting that they could benefit more from early prevention.

Cell-cycle characteristics - alterable determinants of remission duration in a study of 179 standard risk newly diagnosed patients with acute myeloid-leukemia

Prognostic factors were related to remission duration among 179 standard risk newly diagnosed acute myeloid leukemia (AML) patients who received identical induction and consolidation therapies. Following a bromodeoxyuridine infusion, labeling indices of bone marrow aspirate/biopsy, durations of S-phase and cell cycle (Tc) were determined. Patients with slowly cycling myeloblasts had longer remissions (Log rank p=0.03) than those with rapidly cycling myeloblasts. Multivariate analysis demonstrated that both WBC and Tc contributed to remission duration (p=0.01 and 0.005 respectively). Patients with slowly proliferating leukemias have longer remissions probably due to slower regrowth of leukemia between chemotherapy courses.

Laboratory based experiments to assess the use of green and food based compost to improve water quality in a Sustainable Drainage (SUDS) device such as a swale

Many tonnes of compost are generated per year due to door step composting of both garden and kitchen waste. Whilst there are commercial outlets for the finer grade of compost (<10mm) in plant nurseries, there is little demand for the coarser material (>25 mm). This paper reports part of a WRAP-sponsored (Waste Resources Action Programme) study which investigated the potential for green (GC) and mixed green and food (MC) composts to be incorporated into Sustainable Drainage (SUDS) devices such as swales, and replace the topsoil (TS) onto which turf is laid or grass seed distributed. However, it is not known whether compost can replace TS in terms of pollutant remediation, both the trapping of polluted particulates and in dealing with hydrocarbons such as oil, but also from a biofilm development and activity perspective. Using laboratory based experiments utilising leaching columns and an investigation of microbiological development in the composts studied, it was found that many of the differences in performance between MC and GC were insignificant, whilst both composts performed better in terms of pollutant retention than TS. Mixed compost in particular could be used in devices where there may be oil spillages, such as the lorry park of a Motorway Service Area due to its efficiency in degrading oil. Samples of GC and MC were found to contain many of the bacteria and fungi necessary for an active and efficient biofilm which would be an argument in their favour for replacement of TS and incorporation in swales.