3,922 research outputs found
Experimental evaluation of outer planets probe thermal insulation concepts
An experimental program was conducted to evaluate various thermal insulation concepts for use in the Outer Planets Probe (OPP) during entry and descent into the atmospheres of Jupiter, Saturn, and Uranus. Phenolic fiberglass honeycomb specimens representative of the OPP structure were packed and tested with various fillers: Thermal conductivity measurements were made over a temperature range of 300 K to 483 K and pressures from vacuum up to 10 atmospheres in helium and nitrogen gas environments. The conductivity results could not be fully explained so new test specimens were designed with improved venting characteristics, and tested to determine the validity of the original data. All of the conductivity data showed results that were substantially higher than expected. The original test data in helium were lower than the data from the redesigned specimens, probably due to inadequate venting of nitrogen gas from the original specimens. The thermal conductivity test results show only a marginal improvement in probe thermal protection performance for a filled honeycomb core compared to an unfilled core. In addition, flatwise tension tests showed a severe bond strength degradation due to the inclusion of either the powder or foam fillers. In view of these results, it is recommended that the baseline OPP design utilize an unfilled core
Outer planets probe testing
An atmospheric entry Probe is being developed by NASA Ames Research Center (ARC) to conduct in situ scientific investigations of the outer planets' atmospheres. A full scale engineering model of an MDAC-E Probe configuration, was fabricated by NASA ARC. Proof-of-concept test validation of the structural and thermal design is being obtained at NASA ARC. The model was successfully tested for shock and dynamic loading and is currently in thermal vacuum testing
Would You Choose to be Happy? Tradeoffs Between Happiness and the Other Dimensions of Life in a Large Population Survey
A large literature documents the correlates and causes of subjective well-being, or happiness. But few studies have investigated whether people choose happiness. Is happiness all that people want from life, or are they willing to sacrifice it for other attributes, such as income and health? Tackling this question has largely been the preserve of philosophers. In this article, we find out just how much happiness matters to ordinary citizens. Our sample consists of nearly 13,000 members of the UK and US general populations. We ask them to choose between, and make judgments over, lives that are high (or low) in different types of happiness and low (or high) in income, physical health, family, career success, or education. We find that people by and large choose the life that is highest in happiness but health is by far the most important other concern, with considerable numbers of people choosing to be healthy rather than happy. We discuss some possible reasons for this preference
Outer planet probe engineering model thermal vacuum test
A thermal vacuum test was performed on the engineering model of the outer planets atmospheric entry probe. Steady state runs at three simulated radioisotope heating unit loads and one transient run simulating the pre-entry power profile were made to determine the thermal characteristics of the engineering model. An analytic simulation of the model was correlated to the test data. Several steady state and one transient run were made with the model attached to the spacecraft adapter to determine the thermal interface between the model and the adapter
Speeding up simulations of relativistic systems using an optimal boosted frame
It can be computationally advantageous to perform computer simulations in a
Lorentz boosted frame for a certain class of systems. However, even if the
computer model relies on a covariant set of equations, it has been pointed out
that algorithmic difficulties related to discretization errors may have to be
overcome in order to take full advantage of the potential speedup. We summarize
the findings, the difficulties and their solutions, and show that the technique
enables simulations important to several areas of accelerator physics that are
otherwise problematic, including self-consistent modeling in three-dimensions
of laser wakefield accelerator stages at energies of 10 GeV and above.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July
2009, eConf C09072
"Das schnelle Date". Internetgestützte Sexkontakte und HIV-Infektionsrisiko. Ergebnisse einer 2006 durchgeführten Internetbefragung
Der seit Ende der 1990er Jahre diskutierten Frage, ob bei Sexualkontakten, die über Kontaktseiten
im Internet hergestellt werden, in geringerem Umfang präventive Vorkehrungen in Hinblick auf
HIV-Übertragungen erfolgen als bei andernorts angebahnten Kontakten, sollte in einer im
Frühjahr 2006 durchgeführten Online-Umfrage nachgegangen werden. Die Umfrage erfolgte
über vier Dating-Portale für heterosexuelle Frauen und Männer und über vier Portale für homound
bisexuelle Männer. Von den berücksichtigten 5.050 Fragebögen entfielen 76 Prozent auf
Männer, die ausschließlich gleichgeschlechtliche Sexualkontakte in den 12 Monaten vor der
Befragung angaben, 11 Prozent der Männer wurden aufgrund ihrer Angaben als bisexuell und
weitere 11 Prozent als heterosexuell definiert. Frauen stellten lediglich 2 Prozent der
BefragungsteilnehmerInnen.
Etwa drei Viertel aller Befragten schätzten an Kontaktseiten, das sie darüber Menschen „mit
gleichen Vorlieben“ kennenlernen können, dabei muss es sich nicht um sexuelle Vorlieben
handeln: So haben etwa 22 Prozent der Frauen, 12 Prozent der homosexuellen, 9 Prozent der
heterosexuellen und 6 Prozent der bisexuellen Männer überhaupt keine(n) Sexpartner(in) in den
12 Monaten vor der Befragung gesucht. Online gesucht aber keine(n) Partner(in) gefunden haben
18 Prozent der Frauen, 21 Prozent der homosexuellen, 24 Prozent der bisexuellen und 45 Prozent
der heterosexuellen Männer.
Etwa die Hälfte der homo- und bisexuellen Männer haben ihre SexualpartnerInnen mehrheitlich
oder ausschließlich über das Internet kennengelernt, während dies nur auf 39 Prozent der
heterosexuellen Männer zutrifft (zwei Drittel geben dies in der kleinen Gruppe der Frauen an).
Dass heterosexuelle Männer die geringsten Erfolge beim Anbahnen von Sexualkontakten über
das Internet haben, zeigen auch andere erhobene Daten.
Unter den Befragungsteilnehmern erfolgte regelmäßiger Kondomgebrauch bei Vaginal- oder
Analverkehr – je nach Gruppenzugehörigkeit - zu sehr unterschiedlichen Anteilen. 55 Prozent
der homosexuellen und 47 Prozent der bisexuellen Männer benutzten grundsätzlich Kondome,
38 Prozent der heterosexuellen Männer und 34 Prozent der Frauen gaben dies an. Hinsichtlich
des Risikos, sich mit HIV zu infizieren (ungeschützter Anal- oder Vaginalverkehr mit
PartnerInnen mit unbekanntem oder diskordantem Serostatus - Expositionsrisiko), bestanden
nur geringe Unterschiede zwischen homo- (27%), bi- (31%) und heterosexuellen Männern (26%)
bzw. Frauen (27%). Ein Transmissionsrisiko konnte lediglich in der Teilgruppe der
homosexuellen (8%) und bisexuellen (1%) Männer festgestellt werden, da in den anderen beiden
Gruppen niemand HIV-positiv war.
Es zeigt sich, dass bei der überwiegenden Mehrheit aller Befragten das HIV-bezogene sexuelle
Risikoverhalten bei online- und offline-Dates gleich ist.
Are people more likely to risk an HIV infection with sex partners they meet online as compared to
those whom they meet offline? This question has been the subject of research since the late 1990s
in several post-industrialized countries. This paper presents the results of a study conducted in
Germany in 2006. A link to an anonymous, self-administered online questionnaire was posted on
four dating websites for heterosexual men and women and on four dating websites for men who
have sex with men. Of the 5,050 respondents included in the analysis, 76 per cent were men who
reported sexual contacts in the previous twelve months exclusively with other men; 11 per cent
could be classified as bisexual men (sexual contacts with men and women), and 11 per cent as
heterosexual men (sexual contact with women only).. Two per cent of all respondents were
women; because of the small number of respondents this group was not further stratified in the
analysis.
Finding persons “with similar interests” was the most frequently expressed positive aspect of
dating websites (78% among homosexual men, 80% among bisexual men, 74% among
heterosexual men, and 73% among women). This did not necessarily mean similar sexual
interests: 22 per cent of the women, 12 per cent of the homosexual men, 6 per cent of the bisexual
men, and 9 per cent of the heterosexual men claimed they had not been looking for sex partners
during their visits to the sites in the previous twelve months. Many respondents reported being
unsuccessful in finding a sex partner online: 18 per cent of the women, 21 per cent of the
homosexual men, 24 per cent of the bisexual men, and 45 per cent of the heterosexual men.
While during the previous twelve months half of the homo- and bisexual men found most (if not
all) of their sex partners on the Internet, the respective proportions were 39 per cent among
heterosexual men, and 67% in the small group of female respondents.
Taken together, heterosexual men were the least successful in finding sex partners on the
Internet.
Regular use of condoms for every anal or vaginal intercourse was reported by 55 per cent of the
homosexual men, 47 per cent of the bisexual men, 38 of the heterosexual men, and 34 per cent of
the women. However, regarding unprotected anal or vaginal intercourse with a sex partner of
unknown or discordant HIV serostatus, the proportions among the different subgroups were very
similar (homosexual men: 27%; bisexual men: 31%; heterosexual men: 26%; women: 27%). The
risk of transmitting a known HIV infection to sex partners was only present among homosexual
(8%) and bisexual (1%) men, primarily because only respondents from these two subgroups
identified as HIV-positive.
For the large majority (83-86%) of men, HIV risk behaviours are the same, regardless if sex
partners are met online or offline
- …