4,339 research outputs found
The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon
The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat
Patterns of recruitment and injury in a heterogeneous airway network model
In respiratory distress, lung airways become flooded with liquid and may collapse due
to surface-tension forces acting on air-liquid interfaces, inhibiting gas exchange. This pa-
per proposes a mathematical multiscale model for the mechanical ventilation of a network
of occluded airways, where air is forced into the network at a fixed tidal volume, allowing
investigation of optimal recruitment strategies. The temporal response is derived from
mechanistic models of individual airway reopening, incorporating feedback on the airway
pressure due to recruitment. The model accounts for stochastic variability in airway di-
ameter and stiffness across and between generations. For weak heterogeneity, the network
is completely ventilated via one or more avalanches of recruitment (with airways recruited
in quick succession), each characterised by a transient decrease in the airway pressure;
avalanches become more erratic for airways that are initially more flooded. However, the
time taken for complete ventilation of the network increases significantly as the network
becomes more heterogeneous, leading to increased stresses on airway walls. The model
predicts that the most peripheral airways are most at risk of ventilation-induced damage.
A positive-end-expiratory pressure (PEEP) reduces the total recruitment time but at the
cost of larger stresses exerted on airway walls
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P-curve analysis of autonomous and controlling motivation priming effects supports their evidential value
Extant literature consistently demonstrates the level of self-determination individuals experience or demonstrate during an activity can be primed. However, considering most of this literature comes from a period wherein p-hacking was prevalent (pre-2015), it may be that these effects reflect false positives. The aim of the present study was to investigate whether published literature showing autonomous and controlling motivation priming effects contain evidential value or not. A systematic literature search was conducted to identify relevant priming research, while set rules determined which effects from each study would be used in p-curve analysis. Two p-curves including 33 effects each were constructed. P-curve analyses, even after excluding surprising effects (e.g., effects large in magnitude), demonstrated that literature showing autonomous and controlling motivation priming effects contained evidential value. The present findings support prior literature suggesting the effects of autonomous and controlling motivation primes exist at the population level. They also reduce (but do not eliminate) concerns from broader psychology that p-hacking may underlie reported effects
Atomic transition frequencies, isotope shifts, and sensitivity to variation of the fine structure constant for studies of quasar absorption spectra
Theories unifying gravity with other interactions suggest spatial and
temporal variation of fundamental "constants" in the Universe. A change in the
fine structure constant, alpha, could be detected via shifts in the frequencies
of atomic transitions in quasar absorption systems. Recent studies using 140
absorption systems from the Keck telescope and 153 from the Very Large
Telescope, suggest that alpha varies spatially. That is, in one direction on
the sky alpha seems to have been smaller at the time of absorption, while in
the opposite direction it seems to have been larger.
To continue this study we need accurate laboratory measurements of atomic
transition frequencies. The aim of this paper is to provide a compilation of
transitions of importance to the search for alpha variation. They are E1
transitions to the ground state in several different atoms and ions, with
wavelengths ranging from around 900 - 6000 A, and require an accuracy of better
than 10^{-4} A. We discuss isotope shift measurements that are needed in order
to resolve systematic effects in the study. The coefficients of sensitivity to
alpha-variation (q) are also presented.Comment: Includes updated version of the "alpha line" lis
Exercise and GLUT4 in human subcutaneous adipose tissue
To examine the effect of acute and chronic exercise on adipose tissue GLUT4 expression, a total of 20 healthy, male subjects performed one of two studies. Ten subjects performed cycle ergometer exercise for 60 min at 73 ± 2% VO2 peak and abdominal adipose tissue samples were obtained immediately before and after exercise and after 3 h of recovery. Another 10 subjects completed 10 days of exercise training, comprising a combination of six sessions of 60 min at 75% VO2 peak and four sessions of 6 Ă 5 min at 90% VO2 peak, separated by 3 min at 40% VO2 peak. Abdominal adipose tissue and vastus lateralis muscle samples were obtained before training and 24 h after the last training session. A single bout of exercise did not change adipose tissue GLUT4 mRNA; however, there was a small, but significant, reduction in adipose tissue GLUT4 protein expression 3 h after exercise. There were no changes in adipose tissue GLUT4 or COXâIV expression following exercise training. In contrast, skeletal muscle GLUT4 and COXâIV were increased by 47% and 44%, respectively following exercise training. The exercise trainingâinduced increase in GLUT4 expression was similar in both type I and type IIa single muscle fibers. Our results indicate that neither a single exercise bout, nor 10 days of exercise training, increased adipose tissue GLUT4, in contrast with the increases observed in skeletal muscle GLUT4 expression
Mental health challenges facing male survivors of child sexual abuse: implications for mental health nurses
Child sexual abuse (CSA) is an issue of epidemic proportions in the United Kingdom (UK) and an international public health problem. Evidence suggests that in the UK one in twenty children have been sexually abused, with one in three not telling anyone about it at the time of the abuse. Conservative estimates suggest that around one in six men have experienced sexual abuse before the age of 18. CSA has been correlated with the development of numerous mental health problems, abused men often displaying externalising behaviours, including substance misuse, âriskyâ sexual behaviours, anti-social behaviour, and offending. This paper reports on one aspect of a research study focusing specifically on male survivors of CSA and its effect on their mental health. Using narrative research, face to face interviews were used to collect the stories of four men who participated in the research. Interviews were audio-recorded and transcribed verbatim. Analysis used a two-phase approach; initially, each narrative was analysed as a whole, with an across transcripts analysis then being carried out identifying shared themes emerging from the individual stories. Whilst findings from the second phase of the analysis identifies four themes, it is the theme of âBlocking the Memoriesâ that is the focus for this paper. Making a valuable contribution to existent knowledge regarding the experiences of men who were sexually abused as children, this paper will help to inform mental health practitioners who are likely to deliver care to male survivors of CSA
Exploring male survivors of childhood sexual abuse experiences of specialist counselling services
Global estimates suggest 5% to 10% of men report experience of childhood sexual abuse (CSA). However, male CSA is significantly underreported, with men being reluctant to disclose due to vulnerability, stigmatisation, homophobic responses, and fearing a loss of masculinity. A lack of research and service provision targeted towards men suggests male survivors of CSA are marginalised. This qualitative study, using a narrative approach, focused on four adult male survivors of CSA. The aim of the study was to explore their experiences of engaging in counselling and support services for CSA from non-statutory and voluntary organisations. Face-to-face narrative interviews were audio-recorded and transcribed verbatim. Analysis was undertaken using a two-phase approach; firstly, each narrative was analysed as a whole, secondly, an across transcripts analysis was carried out to identify shared themes and divergences that emerged from the individual stories. In this paper findings from the second phase of the analysis are presented. Three themes regarding male survivorsâ experiences of specialist counselling services were identified; âTrust Me, Iâm a Doctor,â âTrust me, Iâm a Counsellor,â and âCounsellor or Mother?â This is the first academic study focusing specifically on menâs experience of support for CSA in the United Kingdom from a service user perspective. Making an original contribution to the knowledge base regarding counselling experiences and the effectiveness of therapy for male CSA survivors, it will help to inform professional counselling services who are likely to come into contact with male survivors of CSA
A western diet increases serotonin availability in rat small intestine
Diet-induced obesity is associated with changes in gastrointestinal function and induction of a mild inflammatory state. Serotonin (5-HT) containing enterochromaffin (EC) cells within the intestine respond to nutrients and are altered by inflammation. Thus, our aim was to characterize the uptake and release of 5-HT from EC cells of the rat ileum in a physiologically relevant model of diet-induced obesity. In chow-fed (CF) and Western diet-fed (WD) rats electrochemical methods were used to measure compression evoked (peak) and steady state (SS) 5-HT levels with fluoxetine used to block the serotonin reuptake transporter (SERT). The levels ofmRNAfor tryptophan hydroxylase 1 (TPH1) and SERT were determined by quantitative PCR, while EC cell numbers were determined immunohistochemically. In WD rats, the levels of 5-HT were significantly increased (SS: 19.2±3.7 ±M; peak: 73.5±14.1 ±M) compared with CF rats (SS: 12.3±1.8 ±M; peak: 32.2±7.2 ±M), while SERTdependent uptake of 5-HT was reduced (peak WD: 108% of control versus peak CF: 212% control). In WD rats, there was a significant increase in TPH1 mRNA, a decrease in SERT mRNA and protein, and an increase in EC cells. In conclusion, our data show that foods typical of a Western diet are associated with an increased 5-HT availability in the rat ileum. Increased 5-HT availability is driven by the up-regulation of 5-HT synthesis genes, decreased re-uptake of 5-HT, and increased numbers and/or 5-HT content of EC cells which are likely to cause altered intestinal motility and sensation in vivo. Copyright © 2010 The Endocrine Society. All rights reserved
Body, Self and Consciousness according to TirumĆ«larâs Tirumandiram: A comparative study with Kashmir Ćaivism
Tirumularâs Tirumandiram is the earliest known Tamil treatise on yoga. This text is considered to be both, a devotional work as well as a tantric text. Unlike other major Siddha compositions, Tirumandiram does not contain any section on medicinal preparations or alchemy. It is the only Tamil text where the sections are named tanáčiram. In contrast to the popular pluralistic Ćaiva SiddhÄnta, Tirumandiram, one of the twelve Saiva cannons (tirumurai), is monistic in its philosophy. This study, while elaborating on the metaphysics of the text Tirumandiram, also examines the shared philosophical thoughts between the monistic Kashmir Ćaivism and Tamil Siddha mystics
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