Quick trips to Mars

The design of a Mars Mission Vehicle that would have to be launched by two very heavy lift launch vehicles is described along with plans for a mission to Mars. The vehicle has three nuclear engine for rocket vehicle application (NERVA) boosters with a fourth in the center that acts as a dual mode system. The fourth generates electrical power while in route, but it also helps lift the vehicle out of earth orbit. A Mars Ascent Vehicle (MAV), a Mars transfer vehicle stage, and a Mars Excursion Vehicle (MEV) are located on the front end of this vehicle. Other aspects of this research including aerobraking, heat shielding, nuclear thermal rocket engines, a mars mission summary, closed Brayton cycle with and without regeneration, liquid hydrogen propellant storage, etc. are addressed

Aspects of planar, oblique and interacting shock waves in an ideal dissociating gas

We develop a compact dimensionless framework for the analysis of canonical thermo-chemical nonequilibrium flow fields involving normal, oblique and interacting shock waves. Discontinuous solutions of the conservation equations are coupled with thermodynamic and kinetic models for an ideal dissociating gas. Convenient forms are provided for the variation of the relevant dimensionless parameters across shock waves in dissociating gases. The treatment is carried through in a consistent manner for the pressure–flow deflection angle plane representation of shock wave interaction problems. The contribution of the current paper is a careful nondimensionalization of the problem that yields a tractable formulation and allows results with considerable generality to be obtained

The influence of non-equilibrium dissociation on the flow produced by shock impingement on a blunt body

We describe an investigation of the effects of non-equilibrium thermochemistry on the interaction between a weak oblique shock and the strong bow shock formed by a blunt body in hypersonic flow. This type of shock-on-shock interaction, also known as an Edney type IV interaction, causes locally intense enhancement of the surface heat transfer rate. A supersonic jet is formed by the nonlinear interaction that occurs between the two shock waves and elevated heat transfer rates and surface pressures are produced by the impingement of the supersonic jet on the body. The current paper is motivated by previous studies suggesting that real gas effects would significantly increase the severity of the phenomenon. Experiments are described in which a free-piston shock tunnel is used to produce shock interaction flows with significant gas dissociation. Surprisingly, the data that are obtained show no significant stagnation enthalpy dependence of the ratio of the peak heat transfer rates with and without shock interaction, in contrast to existing belief. The geometry investigated is the nominally two-dimensional flow about a cylinder with coplanar impinging shock wave. Holographic interferometry is used to visualize the flow field and to quantify increases in the stagnation density caused by shock interaction. Time-resolved heat transfer measurements are obtained from surface junction thermocouples about the model forebody. An improved model is developed to elucidate the finite-rate thermochemical processes occurring in the interaction region. It is shown that severe heat transfer intensification is a result of a jet shock structure that minimizes the entropy rise of the supersonic jet fluid whereas strong thermochemical effects are promoted by conditions that maximize the entropy rise (and hence temperature). This dichotomy underlies the smaller than anticipated influence of real gas effects on the heat transfer intensification. The model accurately predicts the measured heat transfer rates. Improved understanding of the influence of real gas effects on the shock interaction phenomenon reduces a significant element of risk in the design of hypersonic vehicles. The peak heat transfer rate for the Edney type IV interaction is shown to be well-correlated, in the weak impinging shock regime, by an expression of the form [equation] for use in practical design calculations

Erektile Dysfunktion bei Männern in der zweiten Lebenshälfte

Zusammenfassung: Hintergrund: Bisherige Studien zur Prävalenz der erektilen Dysfunktion (ED) zeigen unterschiedliche Ergebnisse. Mit der vorliegenden Studie werden die Häufigkeit und graduelle Ausprägung der ED, deren begünstigende Faktoren sowie das Hilfesuchverhalten der Betroffenen untersucht. Stichprobe und Methodik: Eine Zufallsstichprobe von 628 Deutschschweizer Männern (Durchschnittsalter 61,5Jahre) wurde mittels Fragebogen zur sexuellen Funktionsfähigkeit, Komorbidität und zu ihrem Hilfesuchverhalten befragt. Ergebnisse: 9,6% der Befragten berichten über eine vollständige, 18,0% über eine moderate und 41,4% über eine minimale ED. Alle Grade der Störung nehmen mit dem Alter zu und korrelieren mit somatischer bzw. psychischer Komorbidität sowie Medikamenteneinnahme. Nur 3,2% geben an, schon Mittel zur Verbesserung der Erektionsfähigkeit eingenommen bzw. verwendet zu haben. Schlussfolgerungen: Nur ein kleiner Teil von Männern mit ED sucht ärztliche Hilfe. Sachliche Aufklärung und kompetente ärztliche Beratung von Betroffenen erscheinen angesichts der guten Wirksamkeit von PDE-5-Hemmern angebrach

Tabakkonsum bei Erwachsenen mit ADHS

Zusammenfassung: Hintergrund: Untersuchungen aus den USA wiesen Zusammenhänge zwischen der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) und dem Rauchen nach. Bis heute wurden in der Schweiz keine vergleichbaren Studien durchgeführt. Ziel der vorliegenden Arbeit war es, neue Erkenntnisse über die Beziehung der ADHS und dem Tabakkonsum bei erwachsenen ADHS-Patienten aus der Schweiz zu gewinnen. Material und Methoden: Eine schriftliche Befragung zum Tabakkonsum erfolgte bei allen erwachsenen Patienten mit einer ADHS-Diagnose gemäß DSM-IV, die von September 2000 bis Januar 2006 ambulant im Rahmen der Spezialsprechstunde für ADHS der Psychiatrischen Universitätsklinik Zürich behandelt wurden. 100 der 134Patienten konnten in die Studie eingeschlossen werden. Ergebnisse: Der Raucheranteil in der ADHS-Stichprobe lag mit 55% signifikant über dem Raucheranteil in der Schweizer Wohnbevölkerung (31%). Zudem wiesen täglich rauchende ADHS-Patienten eine höhere Konsummenge und stärkere Nikotinabhängigkeit auf und haben früher begonnen, regelmäßig zu rauchen. Ihre Aufhörbereitschaft war hoch und vergleichbar mit Rauchenden aus der Schweizer Wohnbevölkerung. Schlussfolgerungen: Die Resultate dieser Schweizer Studie sind konsistent mit Befunden aus den USA. Viele ADHS-Patienten sind zum Rauchstopp motiviert und sollten in Abhängigkeit ihrer Aufhörmotivation eine Beratung zum Rauchstopp erhalte

Modification of the simple mass balance equation for calculation of critical loads of acidity.

Over the last few years, the simple mass balance equation for the calculation of critical loads of acidity has been gradually modified as the underlying critical load concepts have developed and as problems with particular forms of the equation have been identified, through application in particular countries. The first major update of the equation took place following a workshop held in Vienna, Austria (Hojesky et al. 1993). The workshop was held to discuss problems which had been identified when the then current form of the equation was applied in countries with high rainfall. The problems had largely arisen because of simplifications and assumptions incorporated into the early formulation of the equation. The equation was reformulated to overcome the problems identified at the workshop. However, further problems were identified when the reformulated equation was applied in the UK in situations with a combination of high rainfall, large marine inputs and widespread occurrence of organic soils. A small workshop was, therefore held in Grange-over-Sands, UK in late 1993 to dicuss the problems and to further re-evaluate the equation. The problems had arisen in the UK because of simplifications and assumptions made in the formulation concerning, in particular, cation leaching and uptake. As a result, a more rigorous treatment of these variables was incorporated into the equation. The reformulation of the equation, as derived at the September 1993 workshop is described below

Die subjektive Belastung pflegender Ehepartner von Demenzkranken: Hinweise zur Validität der deutschen Version des Zarit Burden Interviews

Zusammenfassung: Trotz der Vielzahl europäischer Studien über pflegende Angehörige von Demenzkranken gibt es bis heute keine veröffentlichte validierte deutsche Version des am häufigsten angewandten Instruments zur Erfassung der Belastung familiärer Pflegepersonen (Zarit Burden Interview, ZBI). Primäres Ziel dieser Studie war die Analyse der teststatistischen Gütekriterien der deutschen Version des ZBI (G-ZBI). Die Stichprobe bestand aus 37älteren Paaren (n=74), bei denen der Ehemann von einer Demenzerkrankung betroffen war und die Ehefrau den Großteil der Pflege des kranken Partners übernommen hatte. Das G-ZBI weist eine hohe psychometrische Qualität (Cronbachsα=0,91) sowie überzeugende korrelative Zusammenhänge als Validitätshinweise auf (z.B. Wohlbefinden der Pflegeperson, Pflegebedürftigkeit und neuropsychiatrische Symptome des Demenzkranken). Eine Faktorenanalyse als Maß der Konstruktvalidität zeigt uneindeutige Befunde, unterstützt aber die in der Literatur häufig angenommene Eindimensionalität des Instruments. Die psychometrischen Gütekriterien legen nahe, dass das G-ZBI die Qualität eines reliablen und validen Instruments zur Erfassung der subjektiven Belastung pflegender Ehepartner von Demenzkranken besitzt. Die Anwendung des G-ZBI hat praktische und klinische Relevanz bei der Identifikation besonders belasteter und gefährdeter familiärer Pflegepersone

Transition to Mach reflexion of shock waves in steady and pseudosteady flow with and without relaxation

Experiments were conducted in the free-piston shock tube and shock tunnel with dissociating nitrogen and carbon dioxide, ionizing argon and frozen argon to measure the transition condition in pseudosteady and steady flow. The transition condition in the steady flow, in which the wall was eliminated by symmetry, agrees with the calculated von Neumann condition. In the real gases this calculation assumed thermo-dynamic equilibrium after the reflected shock. In the pseudosteady flow of reflexion from a wedge the measured transition angle lies on the Mach-reflexion side of the calculated detachment condition by an amount which may be explained in terms of the displacement effect of the boundary layer on the wedge surface. A single criterion based on the availability of a length scale at the reflexion point explains the difference between the pseudosteady and steady flow transition condition and predicts a hysteresis effect in the transition angle when the shock angle is varied during steady flow. No significant effects on the transition condition due to finite relaxation length could be detected. However, new experiments in which interesting relaxation effects should be evident are suggested

Near-inertial wave scattering by random flows

The impact of a turbulent flow on wind-driven oceanic near-inertial waves is examined using a linearised shallow-water model of the mixed layer. Modelling the flow as a homogeneous and stationary random process with spatial scales comparable to the wavelengths, we derive a transport (or kinetic) equation governing wave-energy transfers in both physical and spectral spaces. This equation describes the scattering of the waves by the flow which results in a redistribution of energy between waves with the same frequency (or, equivalently, with the same wavenumber) and, for isotropic flows, in the isotropisation of the wave field. The time scales for the scattering and isotropisation are obtained explicitly and found to be of the order of tens of days for typical oceanic parameters. The predictions inferred from the transport equation are confirmed by a series of numerical simulations. Two situations in which near-inertial waves are strongly influenced by flow scattering are investigated through dedicated nonlinear shallow-water simulations. In the first, a wavepacket propagating equatorwards as a result from the $\beta$-effect is shown to be slowed down and dispersed both zonally and meridionally by scattering. In the second, waves generated by moving cyclones are shown to be strongly disturbed by scattering, leading again to an increased dispersion.Comment: Accepted for publication in Phys. Rev. Fluid