A microscopic view of secondary ion formation

a b s t r a c t The formation of secondary ions in sputtering is described by combining classical molecular dynamics of the particle kinetics with simple analytical treatments modeling the transfer of kinetic into electronic excitation energy, the transport of excitation away from the point of its generation and the charge transfer between the solid and a sputtered particle. For the simplest case of a metal atom sputtered from a clean metal surface, the predictions of such a model are used to answer a few fundamental questions regarding the ion formation process. The results indicate that the transient local excitation of the bombarded solid plays a dominant role in determining the charge state of a sputtered atom. Moreover, we find that the assumption of a sputtered particle being emitted from an ideal, undisturbed surface with a constant emission velocity -a picture which forms the physical basis of nearly all published secondary ion formation models -is not generally justified

Structural identification of oxidized acyl-phosphatidylcholines that induce platelet activation

Oxidation of low-density lipoprotein (LDL) generates proinflammatory and prothrombotic mediators that may play a crucial role in cardiovascular and inflammatory diseases. In order to study platelet-activating components of oxidized LDL 1-stearoyl-2-arachidonoyl-sn-glycero-3- phosphocholine, a representative of the major phospholipid species in LDL, the 1-acyl-phosphatidylcholines (PC), was oxidized by CuCl2 and H2O2. After separation by high-performance liquid chromatography, three compounds were detected which induced platelet shape change at low micromolar concentrations. Platelet activation by these compounds was distinct from the pathways stimulated by platelet-activating factor, lysophosphatidic acid, lyso-PC and thromboxane A(2), as evidenced by the use of specific receptor antagonists. Further analyses of the oxidized phospholipids by electrospray ionization mass spectrometry structurally identified them as 1-stearoyl-2-azelaoyl-sn-glycero-3-phosphocholine (m/z 694; SAzPC), 1-stearoyl-2-glutaroyl-snglycero-3- phosphocholine (m/z 638; SGPC), and 1-stearoyl-2-( 5-oxovaleroyl)-sn-glycero-3-phosphocholine (m/z 622; SOVPC). These observations demonstrate that novel 1-acyl-PC which had previously been found to stimulate interaction of monocytes with endothelial cells also induce platelet activation, a central step in acute thrombogenic and atherogenic processes. Copyright (C) 2005 S. Karger AG, Basel

Atorvastatin induces associated reductions in platelet P-selectin, oxidized low-density lipoprotein, and interleukin-6 in patients with coronary artery diseases.

The development and progression of atherosclerosis comprises various processes, such as endothelial dysfunction, chronic inflammation, thrombus formation, and lipid profile modification. Statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors that have pleiotropic effects in addition to cholesterol-lowering properties. However, the mechanisms of these effects are not completely understood. Here, we investigated whether atorvastatin affects the levels of malondialdehyde-modified low-density lipoprotein (MDALDL), an oxidized LDL, the proinflammatory cytokine interleukin-6 (IL-6), or platelet P-selectin, a marker of platelet activation, relative to that of LDL cholesterol (LDL-C). Forty-eight patients with coronary artery disease and hyperlipidemia were separated into two groups that were administered with (atorvastatin group) or without (control group) atorvastatin. The baseline MDA-LDL level in all participants significantly correlated with LDL-C (r = 0.71, P < 0.01) and apolipoprotein B levels (r = 0.66, P < 0.01). Atorvastatin (10 mg/day) significantly reduced the LDL-C level within 4 weeks and persisted for a further 8 weeks of administration. Atorvastatin also reduced the MDA-LDL level within 4 weeks and further reduced it over the next 8 weeks. Platelet P-selectin expression did not change until 4 weeks of administration and then significantly decreased at 12 weeks, whereas the IL-6 level was gradually, but not significantly, reduced at 12 weeks. In contrast, none of these parameters significantly changed in the control group within these time frames. The reduction (%) in IL-6 between 4 and 12 weeks after atorvastatin administration significantly correlated with that of MDALDL and of platelet P-selectin (r = 0.65, P < 0.05 and r = 0.70, P < 0.05, respectively). These results suggested that the positive effects of atorvastatin on the LDL-C oxidation, platelet activation and inflammation that are involved in atherosclerotic processes are exerted in concert after lowering LDL-C

Computer simulation of internal electron emission in ion-bombarded metals

a b s t r a c t We present a computer simulation study of internal electron emission in ion-bombarded metal-insulator-metal (MIM) junctions. The computational approach consists of (i) a molecular dynamics part describing the particle kinetics upon projectile impact, (ii) the computation of kinetic electronic excitation as well as its transport and (iii) a thermionic model to calculate the flux of electrons from the top electrode to the bottom electrode of the MIM. The results are compared to recent experiments and discussed in terms of different transport models for the description of hot electron propagation in metals

the Course in Medical Sociology in Hamburg

The Department of Medical Sociology as part of the Medical Faculty of the University of Hamburg has developed a teaching concept focussing on doctor-patient-communication. Elements of the framework for implementing the concept are: 12 hours for the whole course, teaching has to be provided for 20 groups per year, continuous evaluation by students. Each student has to conduct an interview with an (ex-)patient on "patient's view of illness and health care". There is one teaching session about 4 hours for preparation, and another one for discussion of experiences with and results of the interviews.The concept takes into consideration the requirements both of the official curriculum for medical sociology and the new national regulations for physicans' examinations (Ärztliche Appprobationsordnung). In conclusion, a teaching model which is based on having the first experience of a structured patient interview is feasible for about 400 students in their first semester. The concept and in particular the interview are well accepted and positively evaluated by the students. In the last term, mean of overall satisfaction is about 5 on a 6-point agreement scale. The concept of the course in medical sociology (conducting a patient interview) can be applied in other universities. However, transferability depends on a time frame of about 0,75 hours per week during the semester.Im Institut für Medizin-Soziologie der Medizinischen Fakultät Hamburg wurde ein Kurskonzept für das erste Semester entwickelt, das die Arzt-Patienten-Interaktion ins Zentrum stellt. Rahmenbedingungen für die Umsetzung sind: 0,8 Semesterwochenstunden (= ca. 12 Untersichtsstunden), 20 Kurs-Gruppen jährlich einmal im Wintersemester, kontinuierliche studentische Evaluationen.Als Kernelement des Kurses wird von jedem Studierenden ein Interview mit einem (Ex-)Patienten geführt. In je einem Zeitblock von ca. 4 Unterrichtsstunden wird das Interview vor- und nachbereitet. Als Hilfestellung dient ein Skript zum Thema des Kurses "Kranksein und Krankenbehandlung aus Patientensicht". Das Konzept berücksichtigt sowohl den Gegenstandskatalog der Medizinischen Soziologie als auch die Forderung der Approbationsordnung nach stärkeren klinischen Bezügen im Abschnitt Medizin 1.Als Schlussfolgerungen lassen sich festhalten: Ein Kursmodell für ca. 400 Studierende, in dessen Zentrum die erste Erfahrung eines strukturierten Gesprächs mit (Ex-)Patienten steht, ist machbar. Die Ergebnisse der studentischen Evaluation zeigen, dass der Kurs im Verlauf von vier Semestern zunehmend positiv bewertet wird. Im letzten Wintersemester 2005/2006 wird ein Wert von knapp 5 auf einer 6-stufigen Zustimmungsskala im Hinblick auf verschiedene Merkmale der Prozess- und Ergebnisqualität erreicht. Das Konzept ist mit Anpassungen an andere Rahmenbedingungen auch andernorts verwendbar