Klímaváltozás és etika

A bizonytalansági tényezők immár nem a klímaváltozás, a Föld több fokos átlaghőmérséklet-növekedésének tényére vonatkoznak, mint korábban sok tudós vélte, hanem kizárólag arra, hogy milyen mértékben, milyen gyorsan zajlik le, és mely területeket érinti az éghajlatváltozás. A legkomolyabb probléma az, hogy a hihetetlenül komplex és kaotikus meteorológiai rendszert teljesen „összekavarhatja” az átlaghőmérséklet már egy-két fokos növekedése is. Ennek hatásait egész egyszerűen képtelenség felmérni: vezethet elhúzódó viharokhoz az atmoszféra bármely rétegében, de hosszú aszályok-hoz és egyéb szélsőséges időjárási jelenségekhez is. E kihívásra csak a környezettudatos gazdálkodás és üzletpolitika adhat megoldást. Dolgozatában erre mutat be példát a szerző

Evans-Osteotomie kombiniert mit modifizierter Müller-Niederecker-Sehnenverlagerung bei juvenilem Plattfuß

Der juvenile Plattfuß ist die häufigste Fußfehlstellung und Gegenstand aktueller Diskussionen. Treten therapieresistente Schmerzen auf, besteht häufig die Indikation zur Operation. Hier gibt es eine Vielzahl verschiedener Methoden. Ziel der durchgeführten Untersuchung war es, die Evans-Osteotomie kombiniert mit modifizierter Müller-Niederecker-Sehnenverlagerung zu evaluieren. Dafür wurden in dieser retrospektiven Studie 26 Patienten (46 Füße), die im Alter von 6 bis 16 (11,3 ± 2,2) Jahren operiert wurden, nach durchschnittlich 32,4 Monaten nachuntersucht. Gemäß der Pathogenese der Fußdeformität wurden sie in zwei Gruppen eingeteilt: Gruppe A mit primärem Knickplattfuß, Gruppe B mit sekundärem bei infantiler Cerebralparese. Es wurden klinische und radiologische Untersuchungen sowie eine kinetische und kinematische Ganganalyse mit Kontrollgruppe durchgeführt. Postoperativ zeigte sich ein signifikanter Rückgang der Schmerzsymptomatik auf durchschnittlich 0,1 Punkte der numerischen Rating-Skala. 88,5% der Patienten waren „sehr zufrieden“ mit ihrer Lebensqualität. Bei der klinischen Ankle-Hindfoot Scale konnte in Gruppe A ein Durchschnittswert von 94,5 (82-100 min.-max.) erreicht werden, beim Maryland Foot Score 95,5 (82-100 min.-max.). Komplikationen traten in unserem Patientenkollektiv nicht auf. In der Röntgenun-tersuchung zeigte sich eine signifikante Verbesserung bei folgenden Winkeln: Kalkaneus-Boden-Winkel (20,4°, 9-36° min.-max.), Talus-Neigungswinkel (22,7°, 13-31° min.-max.), Kuboid-Abduktionswinkel (0,8°, -17-17° min.-max.), dorsoplantarer Talus-Kalkaneus-Winkel (19,8°, 10-30° min.-max.), lateraler Talus-Metatarsale-I-Winkel (2,7°, -23-27° min.-max.). Bei 19,6% der Füße waren radiologisch osteophytäre Anbauten im Kalkaneo-Kuboid-Gelenk sichtbar. In der Ganganalyse konnten vor allem im Hinblick auf die Verlagerung der Sehne des M. tibialis anterior lediglich geringfügige Unterschiede von wenigen Grad zwischen Gruppe A und Kontrollgruppe detektiert werden, die keine Auswirkung auf ein physiologisches Gangbild zu haben scheinen. Vielmehr sollte in zukünftigen Studien überprüft werden, in wie weit sich das Gangbild durch die Korrektur der Deformität verbessert. Im Vergleich mit anderen Operationsmethoden zeigte sich, dass die Evans-Osteotomie in Kombination mit modifizierter Müller-Niederecker-Sehnenverlagerung sehr gute Ergebnisse bringt und dabei sehr komplikationsarm ist. Langzeitergebnisse, vor allem im Bezug auf arthrotische Veränderungen im Kalkaneo-Kuboid-Gelenk, sowie eine präoperative Ganganalyse sollten Gegenstand weiterer Untersuchungen werden

Analyse der RS,cis/trans-Tocotrienole

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DWBA analysis of the 13C(6Li,d)17O reaction at 10 MeV/nucleon and its astrophysical implications

The value of the alpha spectroscopic factor (S_alpha) of the 6.356 MeV 1/2+ state of 17O is believed to have significant astrophysical implications due to the importance of the 13C(alpha,n)16O reaction as a possible source of neutron production for the s process. To further study this effect, an accurate measurement of the 13C(6Li,d)17O reaction at E_lab = 60 MeV has been performed recently by Kubono et al., who found a new value for the spectroscopic factor of the 6.356 MeV 1/2+ state of 17O based on a distorted wave Born approximation (DWBA) analysis of these data. This new value, S_alpha approximately = 0.011, is surprisingly much smaller than those used previously in astrophysical calculations (S_alpha approximately = 0.3-0.7) and thus poses a serious question as to the role of the 13C(alpha,n)16O reaction as a source of neutron production. In this work we perform a detailed analysis of the same 13C(6Li,d)17O data within the DWBA as well as the coupled reaction channel (CRC) formalism. Our analysis yields an S_alpha value of over an order of magnitude larger than that of Kubono et al. for the 6.356 MeV 1/2+ state of 17O.Comment: 17 pages, 4 figures, minor changes, accepted by Nuclear Physics

Neutron spectroscopy of 26Mg states : Constraining the stellar neutron source 22Ne(α,n)25Mg

This work reports on accurate, high-resolution measurements of the 25Mg(n,γ)26Mg and 25Mg(n,tot) cross sections in the neutron energy range from thermal to about 300 keV, leading to a significantly improved 25Mg(n,γ)26Mg parametrization. The relevant resonances for n+25Mg were characterized from a combined R-matrix analysis of the experimental data. This resulted in an unambiguous spin/parity assignment of the corresponding excited states in 26Mg. With this information experimental upper limits of the reaction rates for 22Ne(α,n)25Mg and 22Ne(α,γ)26Mg were established, potentially leading to a significantly higher (α,n)/(α,γ) ratio than previously evaluated. The impact of these results has been studied for stellar models in the mass range 2 to 25 M⊙

Neutron production in (α,n) reactions

Neutrons can induce background events in underground experiments looking for rare processes. Neutrons in a MeV range are produced in radioactive decays via spontaneous fission and () reactions, and by cosmic rays. Neutron fluxes from radioactivity dominate at large depths ( km w. e.). A number of computer codes are available to calculate cross-sections of () reactions, excitation functions and neutron yields. We have used EMPIRE2.19/3.2.3 and TALYS1.9 to calculate neutron production cross-sections and branching ratios for transitions to the ground and excited states, and modified SOURCES4A to evaluate neutron yields and spectra in different materials relevant to high-sensitivity underground experiments. We report here a comparison of different models and codes with experimental data, to estimate the accuracy of these calculations

Helium burning and neutron sources in the stars

Helium burning represents an important stage of stellar evolution as it contributes to the synthesis of key elements such as carbon, through the triple-alfa process, and oxygen, through the 12C(alfa, gamma)16O reaction. It is the ratio of carbon to oxygen at the end of the helium burning stage that governs the following phases of stellar evolution leading to different scenarios depending on the initial stellar mass. In addition, helium burning in Asymptotic Giant Branch stars, provides the two main sources of neutrons, namely the 13C(alfa, n)16O and the 22Ne(alfa, n)25Mg, for the synthesis of about half of all elements heavier than iron through the s-process. Given the importance of these reactions, much experimental work has been devoted to the study of their reaction rates over the last few decades. However, large uncertainties still remain at the energies of astrophysical interest which greatly limit the accuracy of stellar models predictions. Here, we review the current status on the latest experimental efforts and show how measurements of these important reaction cross sections can be significantly improved at next-generation deep underground laboratories

Polymers and protein-conjugates for tissue engineering

The number of patients in our society needing replacement of severed, missing or malfunctioning tissue due to diseases, traumata or age, is high and still growing. Burn wounds, bone diseases, diabetes or liver insufficiency are examples of such suffering. Conventional attempts of remedy like drug supplementation, mechanical devices or xenografts are often unsatisfactory and fall short of the goal of enabling normal life. An innovative therapy approach is Human Tissue Engineering, a discipline dedicated to the field of regenerative medicine. To fulfill the promises raised by first successes, significant research efforts have been designated on this area, focusing on various subjects, such as cells, scaffold materials, culture conditions, bioactive molecules, and others. An important milestone on the route for Tissue Engineered products, was the use of �intelligent� materials, such as biomimetic polymers, which may themselves influence cell adhesion and direct cell development (Chapter 1). Biomimetic substances are designed to mimic a biological environment, insomuch eliciting cellular responses that help the material to better perform the intended task. A polymer with favorable characteristics with regards to its use as scaffold material for Tissue Engineering applications is the poly(ethylene glycol)-block-poly(lactic acid) copolymer. The poly(ethylene glycol) block is responsible for suppression of unspecific protein adsorption, whereas the main advantages of the poly(lactic acid) block is its biodegradability. If the free group of the poly(ethylene glycol) block provides a reactive group, the polymer is easily processed into a biomimetic polymer, by covalent attachment of a bioactive molecule, such as bFGF. Diblock co-polymers with different molecular weight, namely MePEG2PLA20, MePEG2PLA40, and NH2PEG2PLA40 were synthesized and characterized with the goal of obtaining substances processable to mechanically stable scaffolds for in vivo or in vitro experiments and first steps were undertaken towards the in vivo evaluation of these polymers (Chapter 4). Although PEG chains largely suppress undesired protein adsorption, the shielding of the surface is not complete. As randomly adsorbed proteins are likely to interfere with the targeted tissue development, knowledge on the extent of shielding is crucial. We, therefore, investigated the amount of adsorbed protein to different polymers by processing them into thin films and investigating their interactions with proteins using quartz crystal microbalance techniques (Chapter 5). Covalent linking of molecules to polymers has the advantage of constricting their operating range to the tethering site, thus diminishing undesired side-effects. Moreover, as diffusion of these molecules is inhibited, prolonged reaction times might be an additional benefit. Unfortunately, tethering might interfere with conformational changes of the molecules structure required for its interaction with the substrate or might even affect the active center of the molecule. Therefore, knowledge of the reaction site is crucial. Identification of the reaction sites was attempted using insulin as model protein. Therefore, polymers were linked to the proteins via small molecular weight tags. After removal of the polymer chains the succinic acid tags still marked the reaction sites and the modified proteins were characterized to identify the exact location of these tags (Chapter 6). Chemical modification of proteins might alter the physico-chemical properties of the molecules. For example, tethering of hydrophilic polymers, like PEG, enhances the water solubility of the drug. But also modification of proteins by attachment of hydrophobic substances, such as fatty acids, might improve the characteristics of these proteins. Nature often uses fatty acids as membrane tethering moieties. Lipidized proteins are also candidates for alternative administration routes, like the oral route, being more stable and having enhanced adsorption properties. Unfortunately, modification of proteins might deteriorate their biological activity. Therefore, prior to use each synthesized conjugate must be tested in a suitable model system. Here, insulin was chosen as model protein. After attachment of fatty acids, its biological activity was tested in an insulin dependent chondrocyte cell culture system (Chapter 7)