Self-organized transient facilitated atomic transport in Pt/Al(111)

During the course of atomic transport in a host material, impurity atoms need to surmount an energy barrier driven by thermodynamic bias or at ultra-low temperatures by quantum tunneling. In the present article we demonstrate using atomistic simulations that at ultra-low temperature transient inter-layer atomic transport is also possible without tunneling when the Pt/Al(111) impurity/host system self-organizes itself spontaneously into an intermixed configuration. No such extremely fast athermal concerted process has been reported before at ultra low temperatures. The outlined novel transient atomic exchange mechanism could be of general validity. We find that the source of ultra-low temperature heavy particle barrier crossing is intrinsic and no external bias is necessary for atomic intermixing and surface alloying in Pt/Al although the dynamic barrier height is few eV. The mechanism is driven by the local thermalization of the Al(111) surface in a self-organized manner arranged spontaneously by the system without any external stimulus. The core of the short lived thermalized region reaches the local temperature of $\sim 1000$ K (including few tens of Al atoms) while the average temperature of the simulation cell is $\sim 3$ K. The transient facilitated intermixing process also takes place with repulsive impurity-host interaction potential leading to negative atomic mobility hence the atomic injection is largely independent of the strength of the impurity-surface interaction. We predict that similar exotic behaviour is possible in other materials as well.Comment: 12 pages, 8 figures, full paper at: http://www.mfa.kfki.hu/~sule/papers/ptonal.pdf . J. Chem. Phys. (2008), in pres

Calibration of thickness-dependent k-factors for germanium X-ray lines to improve energy-dispersive X-ray spectroscopy of SiGe layers in analytical transmission electron microscopy

We show that the accuracy of energy-dispersive X-ray spectroscopy can be improved by analysing and comparing multiple lines from the same element. For each line, an effective k-factor can be defined that varies as a function of the intensity ratio of multiple lines (e.g. K/L) from the same element. This basically performs an internal self-consistency check in the quantification using differently absorbed X-ray lines, which is in principle equivalent to an absorption correction as a function of specimen thickness but has the practical advantage that the specimen thickness itself does not actually need to be measured

Education and older adults at the University of the Third Age

This article reports a critical analysis of older adult education in Malta. In educational gerontology, a critical perspective demands the exposure of how relations of power and inequality, in their myriad forms, combinations, and complexities, are manifest in late-life learning initiatives. Fieldwork conducted at the University of the Third Age (UTA) in Malta uncovered the political nature of elder-learning, especially with respect to three intersecting lines of inequality - namely, positive aging, elitism, and gender. A cautionary note is, therefore, warranted at the dominant positive interpretations of UTAs since late-life learning, as any other education activity, is not politically neutral.peer-reviewe

Diffusion and jump-length distribution in liquid and amorphous Cu33_{33}Zr67_{67}

Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu$_{33}$Zr$_{67}$ in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability

Effect of strain on surface diffusion in semiconductor heteroepitaxy

We present a first-principles analysis of the strain renormalization of the cation diffusivity on the GaAs(001) surface. For the example of In/GaAs(001)-c(4x4) it is shown that the binding of In is increased when the substrate lattice is expanded. The diffusion barrier \Delta E(e) has a non-monotonic strain dependence with a maximum at compressive strain values (e 0) studied. We discuss the consequences of spatial variations of both the binding energy and the diffusion barrier of an adatom caused by the strain field around a heteroepitaxial island. For a simplified geometry, we evaluate the speed of growth of two coherently strained islands on the GaAs(001) surface and identify a growth regime where island sizes tend to equalize during growth due to the strain dependence of surface diffusion.Comment: 10 pages, 8 figures, LaTeX2e, to appear in Phys. Rev. B (2001). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Screening of MAMLD1 Mutations in 70 Children with 46,XY DSD: Identification and Functional Analysis of Two New Mutations

More than 50% of children with severe 46,XY disorders of sex development (DSD) do not have a definitive etiological diagnosis. Besides gonadal dysgenesis, defects in androgen biosynthesis, and abnormalities in androgen sensitivity, the Mastermind-like domain containing 1 (MAMLD1) gene, which was identified as critical for the development of male genitalia, may be implicated. The present study investigated whether MAMLD1 is implicated in cases of severe 46,XY DSD and whether routine sequencing of MAMLD1 should be performed in these patients

Going Mobile with Primary Care: Smartphone-Telemedicine for Asthma Management in Young Urban Adults (TEAMS)

Background: The majority of adults with persistent asthma have chronically uncontrolled disease and interventions to improve outcomes are needed. We evaluated the efficacy, feasi- bility, and acceptability of a multi-component smartphone-telemedicine program (TEAMS) to deliver asthma care remotely, support provider adherence to asthma management guide- lines, and improve patient outcomes. Methods: TEAMS utilized: (1) remote symptom monitoring, (2) nurse-led smartphone-tele- medicine with self-management training for patients, and (3) Electronic medical record- based clinical decision support software. Adults aged 18-44 (N=33) and primary care providers (N=4) were recruited from a safety-net practice in Upstate New York. Asthma con- trol, quality of life, and FEV1 were measured at 0, 3 and 6 months. Acceptability was assessed via survey and end-of-study interviews. Paired t-test and mixed effects modeling were used to evaluate the effect of the intervention on asthma outcomes. Results: At baseline, 80% of participants had uncontrolled asthma. By 6-months, 80% classi- fied as well-controlled. Improvements in control and quality of life were large (d=1.955, d=1.579). FEV%pred increased 4.2% (d=1.687) with the greatest gain in males, smokers, and lower educational status. Provider adherence to national guidelines increased from 43.3% to 86.7% (CI = 22.11-64.55) and patient adherence to medication increased from 45.58% to 85.29% (CI = 14.79-64.62). Acceptability was 95.7%; In follow up interviews, 29/30 patients and all providers indicated TEAMS worked better than usual care, supported effective self- management, and reduced symptoms over time, which led to greater self-efficacy and motivation to manage asthma. Discussion: Based on these findings, we conclude that smartphone telemedicine could substantially improve clinical asthma management, adherence to guidelines, and patient outcomes

A mixed‐methods analysis of younger adults\u27 perceptions of asthma, self‐management, and preventive care: This isn\u27t helping me none

Background: Young adults (ages 18‐44) have increased emergency department use for asthma and poor adherence to medications. The objective of this mixed‐methods study was to understand experiences with and approaches to managing asthma, of which little is known in this age group. Methods: Surveys (Asthma Control Questionnaire, Asthma Quality of Life Questionnaire) and 1:1 semi‐structured interviews were used to explore experiences with asthma, symptoms, self‐management behaviors, and relationship to asthma control and quality of life. Qualitative data were analyzed using content analysis techniques. Descriptive statistics and bivariate correlations were used to examine distributive characteristics and associations between variables. Results: Forty urban adults participated (mean age 32.7 ± 6.2, 1σ). Coughing was reported nearly 46% more often than wheezing, with 42.5% (17/40) coughing until the point of vomiting most days. Most participants delayed using medication for symptoms due to misperceptions about inhalers. Higher symptom frequency and worse asthma control were associated with greater use of non‐pharmacologic symptom management strategies (r=0.645, p\u3c0.001; r=0.360, p=0.022, respectively). Five themes were identified regarding young adults experiences with asthma: (1) having asthma means being limited and missing out on life; (2) healthcare for asthma is burdensome and other things are more important; (3) there is not enough personal benefit in medical interactions to make preventive care worthwhile; (4) there is insufficient support and education about asthma for adults; and (5) people normalize chronic symptoms over time and find ways of coping that fit with their lifestyle. Conclusions & Clinical Relevance: Young adults may tolerate symptoms without using quick‐relief medication or seeking preventive care. Increasing engagement with preventive services will require decreasing perceived burdens and increasing the personal benefits of care. Evaluating for non‐pharmacologic approaches to managing symptoms and asthma‐related coughing may identify uncontrolled asthma. Enhanced training for clinicians in patient‐centric asthma care may be needed

Serotonin tranporter methylation and response to cognitive behaviour therapy in children with anxiety disorders

Anxiety disorders that are the most commonly occurring psychiatric disorders in childhood, are associated with a range of social and educational impairments and often continue into adulthood. Cognitive behaviour therapy (CBT) is an effective treatment option for the majority of cases, although up to 35-45% of children do not achieve remission. Recent research suggests that some genetic variants may be associated with a more beneficial response to psychological therapy. Epigenetic mechanisms such as DNA methylation work at the interface between genetic and environmental influences. Furthermore, epigenetic alterations at the serotonin transporter (SERT) promoter region have been associated with environmental influences such as stressful life experiences. In this study, we measured DNA methylation upstream of SERT in 116 children with an anxiety disorder, before and after receiving CBT. Change during treatment in percentage DNA methylation was significantly different in treatment responders vs nonresponders. This effect was driven by one CpG site in particular, at which responders increased in methylation, whereas nonresponders showed a decrease in DNA methylation. This is the first study to demonstrate differences in SERT methylation change in association with response to a purely psychological therapy. These findings confirm that biological changes occur alongside changes in symptomatology following a psychological therapy such as CBT