Does oxidative stress shorten telomeres in vivo? A review

The length of telomeres, the protective caps of chromosomes, is increasingly used as a biomarker of individual health state because it has been shown to predict chances of survival in a range of endothermic species including humans. Oxidative stress is presumed to be a major cause of telomere shortening, but most evidence to date comes from in vitro cultured cells. The importance of oxidative stress as a determinant of telomere shortening in vivo remains less clear and has recently been questioned. We, therefore, reviewed correlative and experimental studies investigating the links between oxidative stress and telomere shortening in vivo. While correlative studies provide equivocal support for a connection between oxidative stress and telomere attrition (10 of 18 studies), most experimental studies published so far (seven of eight studies) partially or fully support this hypothesis. Yet, this link seems to be tissue-dependent in some cases, or restricted to particular categories of individual (e.g. sex-dependent) in other cases. More experimental studies, especially those decreasing antioxidant protection or increasing pro-oxidant generation, are required to further our understanding of the importance of oxidative stress in determining telomere length in vivo. Studies comparing growing versus adult individuals, or proliferative versus non-proliferative tissues would provide particularly important insights

Carrier mediated interlayer exchange, ground state phase diagrams and transition temperatures of magnetic thin films

We investigate the influence of the carrier density and other parameters on the interlayer exchange in magnetic thin film systems. The system consists of ferromagnetic and non-magnetic layers where the carriers are allowed to move from layer to layer. For the ferromagnetic layers we use the Kondo-lattice model to describe interactions between itinerant electrons and local moments. The electrons' properties are calculated by a Green's function's equation of motion approach while the magnetization of the local moments is determined by a minimization of the free energy. As results we present magnetic phase diagrams and the interlayer exchange over a broad parameter range. Additionally we can calculate the transition temperatures for different alignments of the ferromagnetic layers' magnetizations.Comment: accepted for publication in Phys. Rev.

TECHNOLOGICAL ADAPTATION TO RESOURCE SCARCITY IN THE U.S. LUMBER INDUSTRY

This paper provides an econometric investigation of the role of a renewable natural resource, sawlogs, in the production of lumber over the period 1950-1974. The economic scarcity of sawlogs is confirmed. Within a given production technology, the potential for substitution among capital, labor and sawlog inputs is greatly restricted but not impossible. Technological change has been strongly labor-saving but has had a negligible effect on wood requirements. Consequently, the real price of lumber has risen, stimulating development of substitute wood products. Continued decline of the industry is anticipated.Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy,