Investigation of a hopping transporter concept for lunar exploration

Performance and dynamic characteristics determined for hopping transporter for lunar exploratio

Scientific results of the Bryotrop expedition to Zaire and Rwanda : 7., life strategies of epiphytic bryophytes from tropical lowland and montane forests, ericaceous woodlands and the Dendrosenecio subpáramo of the eastern Congo basin and the adjacent mountains (Parc National de Kahuzi-Biega/Zaire, Forêt de Nyungwe/Rwanda)

Life strategies of epiphytic bryophytes are studied along an altitudinal gradient from the eastern Congo basin (tropical lowland zone) to the mountains of the East-African graben (tropical subalpine/alpine Zone; BRYOTROP III-transect). Three strategies, Colonists, Perennial shuttle species and Perennial stayers can be observed, which are further subdivided according to their reproduction tactic (high sexual reproductive effort, high asexual reproductive effort, moderately or low sexual and asexual reproductive effort). Of these, only taxa with a long life span (perennials) are of importance, indicating the unchanging and constant ecological conditions and long-lasting microsites, provided by the epiphytic habitats. The basis for the life strategy pattern analysis along the altitudinal gradient were plant sociological investigations and the determination of the mean percentage cover values for the different life strategy categories. By this, the distribution and occurrence of the different strategies within the communities and the altitudinal zones can be shown

Gravity-Induced Shape Transformations of Vesicles

We theoretically study the behavior of vesicles filled with a liquid of higher density than the surrounding medium, a technique frequently used in experiments. In the presence of gravity, these vesicles sink to the bottom of the container, and eventually adhere even on non - attractive substrates. The strong size-dependence of the gravitational energy makes large parts of the phase diagram accessible to experiments even for small density differences. For relatively large volume, non-axisymmetric bound shapes are explicitly calculated and shown to be stable. Osmotic deflation of such a vesicle leads back to axisymmetric shapes, and, finally, to a collapsed state of the vesicle.Comment: 11 pages, RevTeX, 3 Postscript figures uuencode

Diffusing proteins on a fluctuating membrane: Analytical theory and simulations

Using analytical calculations and computer simulations we consider both the lateral diffusion of a membrane protein and the fluctuation spectrum of the membrane in which the protein is embedded. The membrane protein interacts with the membrane shape through its spontaneous curvature and bending rigidity. The lateral motion of the protein may be viewed as diffusion in an effective potential, hence, the effective mobility is always reduced compared to the case of free diffusion. Using a rigorous path-integral approach we derive an analytical expression for the effective diffusion coefficient for small ratios of temperature and bending rigidity, which is the biologically relevant limit. Simulations show very good quantitative agreement with our analytical result. The analysis of the correlation functions contributing to the diffusion coefficient shows that the correlations between the stochastic force of the protein and the response in the membrane shape are responsible for the reduction. Our quantitative analysis of the membrane height correlation spectrum shows an influence of the protein-membrane interaction causing a distinctly altered wave-vector dependence compared to a free membrane. Furthermore, the time correlations exhibit the two relevant timescales of the system: that of membrane fluctuations and that of lateral protein diffusion with the latter typically much longer than the former. We argue that the analysis of the long-time decay of membrane height correlations can thus provide a new means to determine the effective diffusion coefficient of proteins in the membrane.Comment: 12 pages, 8 figure

Giant vesicles at the prolate-oblate transition: A macroscopic bistable system

Giant phospholipid vesicles are shown to exhibit thermally activated transitions between a prolate and an oblate shape on a time scale of several seconds. From the fluctuating contour of such a vesicle we extract ellipticity as an effective reaction coordinate whose temporal probability distribution is bimodal. We then reconstruct the effective potential from which we derive an activation energy of the order of $k_BT$ in agreement with theoretical calculations. The dynamics of this transition is well described within a Kramers model of overdamped diffusion in a bistable potential. Thus, this system can serve as a model for macroscopic bistability.Comment: 10 pages, LaTeX, epsfig, 4 eps figures included, to appear in Europhys. Let

Die Greenlight-Laservaporisation der Prostata zur Therapie des benignen Prostatasyndroms: Entwicklung und Stellenwert

Zusammenfassung: Die Greenlight-Laservaporisation hat in den letzten 10Jahren breiten Einsatz in der Therapie des benignen Prostatasyndroms (BPS) gefunden. Neben der Steigerung der Effektivität des Lasers durch eine Erhöhung der maximalen Leistung auf zunächst 80W und später 120W führten auch die guten Ergebnisse der klinischen Evaluationen zu einer zunehmenden Akzeptanz dieses Lasersystems. In der vorliegenden Arbeit werden wesentliche Ergebnisse der klinischen Evaluation der Technik aus den letzten Jahren dargelegt, an denen Schweizer Kliniken maßgeblich beteiligt waren. Hier sind v.a. die geringe peri- und postoperative Morbidität sowie die bisher guten kurz- und mittelfristigen funktionellen Ergebnisse zu nennen. Neben diesen Vorteilen, die v.a. in der nahezu blutungsfreien Durchführung des Eingriffs begründet liegen, werden jedoch ebenso die Nachteile und Limitationen der Laservaporisation beleuchtet, die möglicherweise auch spezifische klinische Nebenwirkungen zur Folge haben. Der zukünftige Stellenwert der Technik wird daher auch vor dem Hintergrund der noch ausstehenden Langzeitdaten weiter evaluiert werden müsse

Influence of epidermal growth factor on long-term potentiation in the hippocampal slice.

Rat hippocampal slices were perfused with epidermal growth factor (EGF) at a concentration of 10−8 M. EGF is a well known mitogen which exhibits neurotrophic action on neurons of the CNS. During extra- and intracellular recordings in the pyramidal cell body layer of the CA1-region no influence of EGF on evoked potentials was seen if single-pulse or paired-pulse stimulation was used. Furthermore EGF has no influence on the resting membrane potential of the cells investigated. However after tetanic stimulation a significant increase in the magnitude of long-term potentiation was observed. Therefore it is concluded, that EGF might be involved in modulation of neuronal plasticity