Studies of non-conventional configuration closed electron drift thrusters

In this paper, we review recent results obtained for segmented electrode and cylindrical Hall thrusters. A low sputtering graphite segmented electrode, placed at the exit of the annular thruster, is shown to affect the plasma potential distribution in the ceramic channel. This effect appears to be correlated with an observed plume reduction compared to a conventional, nonsegmented thruster. In preliminary experiments a 3-cm thruster was operated in the 50-200 W power range. Two operating regimes, stable and oscillating, were observed and investigated

Ion Collection in Hall Thruster Plumes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77342/1/AIAA-11953-462.pd

Mindfulness-Based Cognitive Therapy (MBCT) For Health Anxiety (Hypochondriasis): Rationale, Implementation and Case Illustration.

Recent research has shown that mindfulness-based cognitive therapy (MBCT) could be a useful alternative approach to the treatment of health anxiety and deserves further investigation. In this paper, we outline the rationale for using MBCT in the treatment of this condition, namely its hypothesised impact on the underlying mechanisms which maintain health anxiety, such as rumination and avoidance, hypervigilance to body sensations and misinterpretation of such sensations. We also describe some of the adaptations which were made to the MBCT protocol for recurrent depression in this trial and discuss the rationale for these adaptations. We use a case example from the trial to illustrate how MBCT was implemented and outline the experience of one of the participants who took part in an 8-week MBCT course. Finally, we detail some of the more general experiences of participants and discuss the advantages and possible limitations of this approach for this population, as well as considering what might be useful avenues to explore in future research

Why alternative teenagers self-harm: exploring the link between non-suicidal self-injury, attempted suicide and adolescent identity

Background: The term ‘self-harm’ encompasses both attempted suicide and non-suicidal self-injury (NSSI). Specific adolescent subpopulations such as ethnic or sexual minorities, and more controversially, those who identify as ‘Alternative’ (Goth, Emo) have been proposed as being more likely to self-harm, while other groups such as ‘Jocks’ are linked with protective coping behaviours (for example exercise). NSSI has autonomic (it reduces negative emotions) and social (it communicates distress or facilitates group ‘bonding’) functions. This study explores the links between such aspects of self-harm, primarily NSSI, and youth subculture.<p></p> Methods: An anonymous survey was carried out of 452 15 year old German school students. Measures included: identification with different youth cultures, i.e. Alternative (Goth, Emo, Punk), Nerd (academic) or Jock (athletic); social background, e.g. socioeconomic status; and experience of victimisation. Self-harm (suicide and NSSI) was assessed using Self-harm Behavior Questionnaire and the Functional Assessment of Self-Mutilation (FASM).<p></p> Results: An “Alternative” identity was directly (r ≈ 0.3) and a “Jock” identity inversely (r ≈ -0.1) correlated with self-harm. “Alternative” teenagers self-injured more frequently (NSSI 45.5% vs. 18.8%), repeatedly self-injured, and were 4–8 times more likely to attempt suicide (even after adjusting for social background) than their non-Alternative peers. They were also more likely to self-injure for autonomic, communicative and social reasons than other adolescents.<p></p> Conclusions: About half of ‘Alternative’ adolescents’ self-injure, primarily to regulate emotions and communicate distress. However, a minority self-injure to reinforce their group identity, i.e. ‘To feel more a part of a group’

Effects of Mindfulness-Based Cognitive Therapy on Specificity of Life Goals

This study explored the immediate effects of a course of Mindfulness-Based Cognitive Therapy (MBCT) for chronically depressed participants with a history of suicidality on the specificity of important goals for the future. Participants were randomly allocated to immediate treatment with MBCT or to a waitlist condition and life goals were assessed both before and after the treatment or waiting period. Results showed that participants receiving MBCT reported significantly more specific goals post-treatment whereas those allocated to the waitlist condition showed no significant change. Similarly, participants allocated to MBCT regarded themselves as significantly more likely to achieve their important goals post-treatment, whilst again there was no significant change in the waitlist group. Increases in goal specificity were associated with parallel increases in autobiographical memory specificity whereas increases in goal likelihood were associated with reductions in depressed mood. These results suggest that MBCT may enable participants to clarify their important goals and in doing so increase their confidence in their capacity to move in valued life directions

Oct4-Induced Reprogramming Is Required for Adult Brain Neural Stem Cell Differentiation into Midbrain Dopaminergic Neurons

Neural stem cells (NSCs) lose their competency to generate region-specific neuronal populations at an early stage during embryonic brain development. Here we investigated whether epigenetic modifications can reverse the regional restriction of mouse adult brain subventricular zone (SVZ) NSCs. Using a variety of chemicals that interfere with DNA methylation and histone acetylation, we showed that such epigenetic modifications increased neuronal differentiation but did not enable specific regional patterning, such as midbrain dopaminergic (DA) neuron generation. Only after Oct-4 overexpression did adult NSCs acquire a pluripotent state that allowed differentiation into midbrain DA neurons. DA neurons derived from Oct4-reprogrammed NSCs improved behavioural motor deficits in a rat model of Parkinson's disease (PD) upon intrastriatal transplantation. Here we report for the first time the successful differentiation of SVZ adult NSCs into functional region-specific midbrain DA neurons, by means of Oct-4 induced pluripotency

Generation of Healthy Mice from Gene-Corrected Disease-Specific Induced Pluripotent Stem Cells

Using the murine model of tyrosinemia type 1 (fumarylacetoacetate hydrolase [FAH] deficiency; FAH−/− mice) as a paradigm for orphan disorders, such as hereditary metabolic liver diseases, we evaluated fibroblast-derived FAH−/−-induced pluripotent stem cells (iPS cells) as targets for gene correction in combination with the tetraploid embryo complementation method. First, after characterizing the FAH−/− iPS cell lines, we aggregated FAH−/−-iPS cells with tetraploid embryos and obtained entirely FAH−/−-iPS cell–derived mice that were viable and exhibited the phenotype of the founding FAH−/− mice. Then, we transduced FAH cDNA into the FAH−/−-iPS cells using a third-generation lentiviral vector to generate gene-corrected iPS cells. We could not detect any chromosomal alterations in these cells by high-resolution array CGH analysis, and after their aggregation with tetraploid embryos, we obtained fully iPS cell–derived healthy mice with an astonishing high efficiency for full-term development of up to 63.3%. The gene correction was validated functionally by the long-term survival and expansion of FAH-positive cells of these mice after withdrawal of the rescuing drug NTBC (2-(2-nitro-4-fluoromethylbenzoyl)-1,3-cyclohexanedione). Furthermore, our results demonstrate that both a liver-specific promoter (transthyretin, TTR)-driven FAH transgene and a strong viral promoter (from spleen focus-forming virus, SFFV)-driven FAH transgene rescued the FAH-deficiency phenotypes in the mice derived from the respective gene-corrected iPS cells. In conclusion, our data demonstrate that a lentiviral gene repair strategy does not abrogate the full pluripotent potential of fibroblast-derived iPS cells, and genetic manipulation of iPS cells in combination with tetraploid embryo aggregation provides a practical and rapid approach to evaluate the efficacy of gene correction of human diseases in mouse models

Methodological issues associated with collecting sensitive information over the telephone - experience from an Australian non-suicidal self-injury (NSSI) prevalence study

<p>Abstract</p> <p>Background</p> <p>Collecting population data on sensitive issues such as non-suicidal self-injury (NSSI) is problematic. Case note audits or hospital/clinic based presentations only record severe cases and do not distinguish between suicidal and non-suicidal intent. Community surveys have largely been limited to school and university students, resulting in little much needed population-based data on NSSI. Collecting these data via a large scale population survey presents challenges to survey methodologists. This paper addresses the methodological issues associated with collecting this type of data via CATI.</p> <p>Methods</p> <p>An Australia-wide population survey was funded by the Australian Government to determine prevalence estimates of NSSI and associations, predictors, relationships to suicide attempts and suicide ideation, and outcomes. Computer assisted telephone interviewing (CATI) on a random sample of the Australian population aged 10+ years of age from randomly selected households, was undertaken.</p> <p>Results</p> <p>Overall, from 31,216 eligible households, 12,006 interviews were undertaken (response rate 38.5%). The 4-week prevalence of NSSI was 1.1% (95% ci 0.9-1.3%) and lifetime prevalence was 8.1% (95% ci 7.6-8.6).</p> <p>Methodological concerns and challenges in regard to collection of these data included extensive interviewer training and post interview counselling. Ethical considerations, especially with children as young as 10 years of age being asked sensitive questions, were addressed prior to data collection. The solution required a large amount of information to be sent to each selected household prior to the telephone interview which contributed to a lower than expected response rate. Non-coverage error caused by the population of interest being highly mobile, homeless or institutionalised was also a suspected issue in this low prevalence condition. In many circumstances the numbers missing from the sampling frame are small enough to not cause worry, especially when compared with the population as a whole, but within the population of interest to us, we believe that the most likely direction of bias is towards an underestimation of our prevalence estimates.</p> <p>Conclusion</p> <p>Collecting valid and reliable data is a paramount concern of health researchers and survey research methodologists. The challenge is to design cost-effective studies especially those associated with low-prevalence issues, and to balance time and convenience against validity, reliability, sampling, coverage, non-response and measurement error issues.</p

Influence of 1α, 25-dihydroxyvitamin D3 [1, 25(OH)2D3] on the expression of Sox 9 and the transient receptor potential vanilloid 5/6 ion channels in equine articular chondrocytes

Background Sox 9 is a major marker of chondrocyte differentiation. When chondrocytes are cultured in vitro they progressively de-differentiate and this is associated with a decline in Sox 9 expression. The active form of vitamin D, 1, 25 (OH)2D3 has been shown to be protective of cartilage in both humans and animals. In this study equine articular chondrocytes were grown in culture and the effects of 1, 25 (OH)2D3 upon Sox 9 expression examined. The expression of the transient receptor potential vanilloid (TRPV) ion channels 5 and 6 in equine chondrocytes in vitro, we have previously shown, is inversely correlated with de-differentiation. The expression of these channels in response to 1, 25 (OH)2D3 administration was therefore also examined. Results The active form of vitamin D (1, 25 (OH)2D3) when administered to cultured equine chondrocytes at two different concentrations significantly increased the expression of Sox 9 at both. In contrast 1, 25 (OH)2D3 had no significant effect upon the expression of either TRPV 5 or 6 at either the protein or the mRNA level. Conclusions The increased expression of Sox 9, in equine articular chondrocytes in vitro, in response to the active form of vitamin D suggests that this compound could be utilized to inhibit the progressive de-differentiation that is normally observed in these cells. It is also supportive of previous studies indicating that 1α, 25-dihydroxyvitamin D3 can have a protective effect upon cartilage in animals in vivo. The previously observed correlation between the degree of differentiation and the expression levels of TRPV 5/6 had suggested that these ion channels may have a direct involvement in, or be modulated by, the differentiation process in vitro. The data in the present study do not support this