Altern und Seneszenz im Hinblick auf die Life-History des Menschen

Die vorliegende Arbeit zeigt, dass Altern und Seneszenz ein breit gefächertes Thema ist und ständig neue Erkenntnisse hinzukommen. Fast alle Lebewesen sind mehr oder weniger von Altern und Seneszenz betroffen und der Alterungsprozess wird nicht nur durch die Gene, sondern auch durch die Umwelt beeinflusst. In der Arbeit wird geprüft, ob die StudentInnen Fragen über das Thema Altern beantworten können. Es stellt sich heraus, dass obwohl das Thema Altern während des Studiums kaum behandelt wird, mehr oder weniger StudentInnen die Fragen richtig beantworten können. Werden die Fragen spezifischer, gehen die Meinungen auseinander oder die Fragen werden manchmal einfach ausgelassen. Am liebsten wurde die Frage, ob die Fortpflanzungsfähigkeit irreversibel ist (n= 24) oder die Bedeutung der Menopause (n= 14) nicht beantwortet. Auch Fragen zum männlichen Geschlecht (Beginn der Geschlechtsreife, Fortpflanzungsfähigkeit) (n= 11) oder die Zuordnung der Werte, bei den Vergleichen verschiedener Säugetiere (bis zu 8 StudentInnen), wurden gerne übersprungen. Die eigene Person betreffend, verschwiegen die StudentInnen bevorzugt ihr Geschlecht (n= 8) oder ihre Studienrichtung (n= 11). Bei der Frage nach der Wirkung von Kosmetik-Produkten ist deutlich zu sehen, dass obwohl das Thema Altern und Kosmetik in den Medien sehr stark vertreten ist, die Wirkung nicht eindeutig ist. Sicher sind sich die meisten, dass diese den Alterungsprozess nicht stoppen können, aber was die Verlangsamung des Prozesses betrifft, sind sich Viele nicht sicher. Hier besteht noch ein hoher Aufklärungsbedarf. Fragen, welche den Menschen betreffen, konnten meist sehr gut beantwortet werden. Bei der Fortpflanzungsfähigkeit des Mannes und der Irreversibilität der Fortpflanzungsfähigkeit der Frau gehören einige StudentInnen noch aufgeklärt. Und auch die Definition eines potenziell unsterblichen Lebewesens könnte Klarheit schaffen. Das Ergebnis fällt somit im Großen und Ganzen gut aus. Anhand der letzten Frage, nach dem Interesse zum Thema Altern ist zu sehen, dass ein großer Wunsch nach mehr Informationen seitens der StudentInnen vorhanden ist. Vielleicht wäre es möglich das Thema mehr in das Studium zu integrieren. Nicht nur die LehramtsstudentInnen können viele Menschen, vor allem Kinder und Jugendliche erreichen und sie über dieses Thema informieren. Auch die anderen StudentInnen haben die Aufgabe Menschen ohne Zugang zu diesem Wissen aufzuklären. Das Studium könnte hierzu eine entscheidende Grundlage liefern. Wie wichtig die Auseinandersetzung mit dem Thema Altern ist, zeigt die starke Veränderung der Bevölkerungspyramide einiger Länder. Immer mehr Menschen erreichen ein hohes Alter, wodurch das Thema Altern immer mehr an Bedeutung gewinnt. Wer kümmert sich zukünftig um die alten Menschen und welche finanziellen Mittel stehen zur Verfügung? Setzen wir uns rechtzeitig mit dieser Materie auseinander, können wir in Zukunft besser und vernünftiger damit umgehen. Je früher desto besser.The work in hand shows that aging and senescence are not only broadly topics, but also permanently undergo new findings. Almost every living organism is more or less affected by aging and senescence and the aging process in general is influenced by genes and the environment. The aim of this work should be to prove whether students can answer questions on the topic aging, or not. It appears that although the topic aging is hardly discussed during the biology studies, students are able to answer the questions more or less correctly. If the questions get more specific, the opinions differ or sometimes the questions are not answered but simply left out. Questions on the irreversibility of the fecundity and on the meaning of the menopause were not answered most of the times. Questions concerning the male sex or the assignment of the values, regarding the comparison of different mammals were also often ignored. Some of the interviewed persons wanted to remain anonymous and hence, did not provide any information on their sex nor branch of study. In case of the question on the effects of cosmetic products it can be seen that although the topics aging and cosmetics are currently present in the media, the effects are still not clear. The majority of interviewees are convinced that cosmetics cannot stop the aging process but they are not well informed about the slowdown impact of such products. As one can see this topic still requires considerable clarification. Questions concerning the human being were answered easily. However, regarding male fecundity and female irreversibility of fecundity, there is a knowledge gap with some students, who still need additional information. The definition of a potential immortal living organism could establish clarity. Altogether one can say that the interview results are satisfying. The interest concerning the topic aging and the need for more detailed information in this field shows that it would probably be a good idea to deal with that topic during the biology studies in greater detail. It is not only the future teachers who are able to inform their students about their knowledge on this subject matter, but every biology student who could provide important information for those who do not have any access to this topic area. The constant change of the population pyramid in some countries clearly shows the importance of this subject matter. As the life expectancy of people is constantly increasing the topic aging gains more and more significance. Who will take care of the elderly in the future and which financial resources could be used to support those affected? If we start dealing with this topic matter now, the chance of finding a satisfactory solution will be more realistic - the sooner the better

Synthetic photometry for M and K giants and stellar evolution: hydrostatic dust-free model atmospheres and chemical abundances

Based on a grid of hydrostatic spherical COMARCS models for cool stars, we have calculated observable properties of these objects, which will be mainly used in combination with stellar evolution tracks and population synthesis tools. The high-resolution opacity sampling and low-resolution convolved spectra as well as bolometric corrections for a large number of filter systems are made electronically available. We exploit those data to study the effect of mass, C/O ratio and nitrogen abundance on the photometry of K and M giants. Depending on effective temperature, surface gravity and the chosen wavelength ranges, variations of the investigated parameters cause very weak to moderate and, in the case of C/O values close to 1, even strong shifts of the colours. For the usage with stellar evolution calculations, they will be treated as correction factors applied to the results of an interpolation in the main quantities. When we compare the synthetic photometry to observed relations and to data from the Galactic bulge, we find in general a good agreement. Deviations appear for the coolest giants showing pulsations, mass-loss and dust shells, which cannot be described by hydrostatic models

Atmospheric dynamics in carbon-rich Miras. I. Model atmospheres and synthetic line profiles

Atmospheres of evolved AGB stars are heavily affected by pulsation, dust formation and mass loss, and they can become very extended. Time series of observed high-resolution spectra proved to be a useful tool to study atmospheric dynamics throughout the outer layers of these pulsating red giants. Originating at various depths, different molecular spectral lines observed in the near-infrared can be used to probe gas velocities there for different phases during the lightcycle. Dynamic model atmospheres are needed to represent the complicated structures of Mira variables properly. An important aspect which should be reproduced by the models is the variation of line profiles due to the influence of gas velocities. Based on a dynamic model, synthetic spectra (containing CO and CN lines) were calculated, using an LTE radiative transfer code that includes velocity effects. It is shown that profiles of lines that sample different depths qualitatively reproduce the behaviour expected from observations.Comment: accepted by A&A, 12 pages, 9 figure

Synthetic photometry for carbon-rich giants II. The effects of pulsation and circumstellar dust

By using self-consistent dynamic model atmospheres which simulate pulsation-enhanced dust-driven winds of AGB stars we studied in detail the influence of (i) pulsations of the stellar interiors, and (ii) the development of dusty stellar winds on the spectral appearance of long period variables with carbon-rich atmospheric chemistry. While the pulsations lead to large-amplitude photometric variability, the dusty envelopes cause pronounced circumstellar reddening. Based on one selected dynamical model which is representative of C-type Mira variables with intermediate mass loss rates, we calculated synthetic spectra and photometry for standard broad-band filters from the visual to the near-infrared. Our modelling allows to investigate in detail the substantial effect of circumstellar dust on the resultant photometry. The pronounced absorption of amorphous carbon dust grains leads to colour indices which are significantly redder than the corresponding ones based on hydrostatic dust-free models. Only if we account for this circumstellar reddening we get synthetic colours that are comparable to observations of evolved AGB stars. The photometric variations of the dynamical model were compared to observed lightcurves of the C-type Mira RU_Vir which appears to be quite similar to the model. We found good agreement concerning the principal behaviour of the BVRIJHKL lightcurves and also quantitatively fitting details. The analysed model is able to reproduce the variations of RU_Vir and other Miras in (J-H) vs. (H-K) diagrams throughout the light cycle. Contrasting the model photometry with observational data for a variety of galactic C-rich giants in such colour-colour diagrams proved that the chosen atmospheric model fits well into a sequence of objects with increasing mass loss rates, i.e., redder colour indices.Comment: Accepted for publication in A&

Mid- and Far-Infrared Properties of Dynamical Models of Cabon-Rich . . .

. We have calculated spectral energy distributions and synthetic IRAS colours of carbon-rich long-period variables. On top of dynamical models for the stellar atmosphere and circumstellar envelope which consistently treat the timedependent hydrodynamics, the formation of amorphous carbon grains and grey radiative transfer, frequency-dependent radiative transfer calculations have been carried out in the range between 1 ¯m and 290 ¯m. Calculating the IRAS colours we find that the models lie in regions I (stars without circumstellar shells) and VII (variable stars with carbon-rich circumstellar shells) of the IRAS two colour diagram in accordance with observational results for carbon stars. They form an almost linear sequence (near the black body line) reflecting the different mass loss rates. We compare our results to empirical formulae which link the mass loss rate to the observed flux at 60 ¯m. Furthermore, we have also investigated qualitatively the effects of dust with ff-SiC grains ..