Restricted configuration path integral Monte Carlo.

Quantum Monte Carlo (QMC) belongs to the most accurate simulation techniques for quantum many-particle systems. However, for fermions, these simulations are hampered by the sign problem that prohibits simulations in the regime of strong degeneracy. The situation changed with the development of configuration path integral Monte Carlo (CPIMC) by Schoof et al. [Contrib. Plasma Phys. 51, 687 (2011)] that allowed for the first ab initio simulations for dense quantum plasmas [Schoof et al., Phys. Rev. Lett. 115, 130402 (2015)]. CPIMC also has a sign problem that occurs when the density is lowered, i.e., in a parameter range that is complementary to traditional QMC formulated in coordinate space. Thus, CPIMC simulations for the warm dense electron gas are limited to small values of the Brueckner parameter-the ratio of the interparticle distance to the Bohr radius-rs=r¯/aB≲1. In order to reach the regime of stronger coupling (lower density) with CPIMC, here we investigate additional restrictions on the Monte Carlo procedure. In particular, we introduce two different versions of "restricted CPIMC"-called RCPIMC and RCPIMC+-where certain sign changing Monte Carlo updates are being omitted. Interestingly, one of the methods (RCPIMC) has no sign problem at all, but it introduces a systematic error and is less accurate than RCPIMC+, which neglects only a smaller class of the Monte Carlo steps. Here, we report extensive simulations for the ferromagnetic uniform electron gas with which we investigate the properties and accuracy of RCPIMC and RCPIMC+. Furthermore, we establish the parameter range in the density-temperature plane where these simulations are both feasible and accurate. The conclusion is that RCPIMC and RCPIMC+ work best at temperatures in the range of Θ = kBT/EF ∼ 0.1…0.5, where EF is the Fermi energy, allowing to reach density parameters up to rs ∼ 3…5, thereby partially filling a gap left open by existing ab initio QMC methods.

Investigation on radiofrequency and laser (980 nm) effects after endoluminal treatment of saphenous vein insufficiency in an ex-vivo model.

OBJECTIVES: An ex-vivo model for the experimental evaluation of endoluminal thermal procedures for occlusion of saphenous veins was developed. Radiofrequency obliteration (RFO) and endovenous laser therapy (ELT) were compared using this model. DESIGN: Experimental ex-vivo treatment study. MATERIALS AND METHODS: The model consists of the subcutaneous foot veins from freshly slaughtered cows which were reperfused in situ with heparinised bovine blood. The veins were treated with either radiofrequency (RFO n=5) or with endoluminal 980 nm laser light (ELT n=5) using a continuous pull-back for RFO and a stepwise illumination and pull-back protocol for ELT. Immediately after treatment perivenous tissue and veins were examined macroscopically. In a second study the same treatment parameters were used in four further vein segments with RFO (n=2) and ELT (n=2). These vein segments were examined microscopically in HE-stained histological sections. RESULTS: Induration of the vessel wall and contraction of the vessel lumen were observed after RFO. Laser treatment produced carbonised lesions of the vein wall. After 12-24 laser exposures these lesions often became transmural, causing complete perforation of the vessel wall. Histological evaluation after radiofrequency treatment demonstrated homogenous circular thermal tissue alteration with disintegration of intima and media structures. Histological evaluation after endovenous laser treatment showed large variations of thermal tissue effects. Tissue effects ranged from major tissue ablation and vessel wall disruption to minor effects located between laser exposures and on the opposite vessel wall. CONCLUSIONS: Our model is suitable for systematic scientific evaluation of endovenous thermal occlusion procedures. Our first results and theoretical considerations indicate that endovenous laser treatment should be modified in order to ensure controlled homogenous circular thermal damage, avoiding vessel wall perforation and damage to perivascular structures.

[The depletion of chemical disinfectants during their use (local consumption)]. / Die Erschöpfung von chemischen Desinfektionsmitteln während ihrer Anwendung (lokaler Verbrauch).

The concentration of chemical disinfectants decreases in the contact volume, where bacteria and the chemical disinfectant meet. This can be described quantitatively if one assumes that the latter is consumed in proportion to the number of bacteria killed. The local consumption is controlled by diffusion and hence depends on the thickness of the contact volume which determines the concentration gradient. Local consumption may drastically affect quantitative tests of chemical disinfectants if no precaution is taken.

[Non-drug modification of blood pressure in a health resort]. / Nichtmedikamentöse Beeinflussung des Blutdruckes zur Kur.

1,049 patients between 30 and 69 years were treated in a sanitarium for 28 days. Here no change of the medicamentous therapy which had influence on the blood pressure took place. As remedies of cure were applied: physical conditional training, changes of nutrition including restriction of calories and Na, physiotherapy including sauna. The average decrease of blood pressure at the end of the cure was in patients with normal blood pressure 4.42 Torr (0.59 kPa) systolically and 3.52 Torr (0.47 kPa) diastolically, in patients with borderline hypertension 15.39 Torr (2.05 kPa) systolically and 6.32 Torr (0.84 kPa) diastolically and in patients with hypertension 27.59 Torr (3.67 kPa) systolically and 11.49 Torr (1.53 kPa) diastolically. In a former year of cure without conditional training and with more insignificant reduction of body weight no reduction of blood pressure was the result in patients with normal blood pressure, in patients with borderline hypertension a clearly more insignificant, and only in patients with hypertension simultaneously using antihypertensive medicaments a similarly expressed reduction of the blood pressure was achieved. On the basis of a rescreening the efforts for a permanent success of the non-medicamentous reduction of the blood pressure was discussed.

Education at school about sexually transmitted diseases.

Although sex education in West German schools started officically in 1968, a survey of 700 children aged 14 to 15 years showed that they understood more about birth control than about sexually transmitted disease (STD). This contrasts with the rising incidence of gonorrhoea and falling birth rate. There is a general lack of published information of STD and it is proposed that an international body like the IUVDT should be formed to promote the spread of information.

[General, non-medicamentous treatment of arterial hypertension]. / Allgemeine, nichtmedikamentöse Behandlung des arteriellen Bluthochdrucks.

This review focuses on the following aspects of nonpharmacological management concerning elevation of blood pressure: historical development, highlights and theses, possibilities of intervention, as well as favorable observations, advantages (in early diagnosis), disadvantages, fields of application, and integration of this form of treatment into a comprehensive strategy of hypertension control at a population level. A selection of detailed results is elaborated including: possible failure in primary classification of elevated blood pressure and its consequences, the reducibility of the hypertension problem if nonpharmacological measures are generally used, risk factor prevalences in medical and non-medical university cadres, blood pressure reduction in a spa, and hemodynamic changes induced by nonpharmacological or combined antihypertensive treatment simultaneously with drugs. Finally, reference is made to international results, as well as to the importance of the relation between diagnosing and treating blood pressure elevation concomitantly with a simultaneous management of other main risk factors that must be influenced in order to reduce the cardiac risk in hypertensives.