An Efficient Molecular Dynamics Scheme for the Calculation of Dopant Profiles due to Ion Implantation

We present a highly efficient molecular dynamics scheme for calculating the concentration depth profile of dopants in ion irradiated materials. The scheme incorporates several methods for reducing the computational overhead, plus a rare event algorithm that allows statistically reliable results to be obtained over a range of several orders of magnitude in the dopant concentration. We give examples of using this scheme for calculating concentration profiles of dopants in crystalline silicon. Here we can predict the experimental profile over five orders of magnitude for both channeling and non-channeling implants at energies up to 100s of keV. The scheme has advantages over binary collision approximation (BCA) simulations, in that it does not rely on a large set of empirically fitted parameters. Although our scheme has a greater computational overhead than the BCA, it is far superior in the low ion energy regime, where the BCA scheme becomes invalid.Comment: 17 pages, 21 figures, 2 tables. See: http://bifrost.lanl.gov/~reed

Met NIRS productieproces en productkwaliteit bewaken : snelle kwaliteitscontrole voor vlees op de werkvloer

Het werken met Nabij InfraRood Spectroscopie vereist professionele kennis en praktische ervaring met deze techniek. Statistische procescontrôle in combinatie met snelle sensoren leidt tot meer inzicht in en grip op het productieproce

Emotional and behavioral problems in children with dilated cardiomyopathy

Background: Dilated cardiomyopathy (DCM) in children is an important cause of severe heart failure and carries a poor prognosis. Adults with heart failure are at increased risk of anxiety and depression and such symptoms predict adverse clinical outcomes such as mortality. In children with DCM, studies examining these associations are scarce. Aims: We studied whether in children with DCM: (1) the level of emotional and behavioral problems was increased as compared to normative data, and (2) depressive and anxiety problems were associated with the combined risk of death or cardiac transplantation. Methods: To assess emotional and behavioral problems in children with DCM, parents of 68 children, aged 1.5–18 years (6.9±5.7 years), completed the Child Behavior Checklist. Results: Compared to normative data, more young children (1.5–5 years) with DCM had somatic complaints (24.3% vs. 8.0%; p <.001), but fewer had externalizing problems (5.4% vs. 17.0%; p =.049). Overall internalizing problems did not reach significance. Compared to normative data, more older children (6–18 years) showed internalizing problems (38.7% vs. 17.0%; p =.001), including depressive (29.0% vs. 8.0%; p <.001) and anxiety problems (19.4% vs. 8.0%; p =.023), and somatic complaints (29.0% vs. 8.0%; p <.001). Anxiety and depressive problems, corrected for heart failure severity, did not predict the risk of death or cardiac transplantation. Conclusion: Children of 6 years and older showed more depressive and anxiety problems than the normative population. Moreover, in both age groups, somatic problems were common. No association with outcome could be demonstrated