Hippocampal volumes are important predictors for memory function in elderly women

<p>Abstract</p> <p>Background</p> <p>Normal aging involves a decline in cognitive function that has been shown to correlate with volumetric change in the hippocampus, and with genetic variability in the APOE-gene. In the present study we utilize 3D MR imaging, genetic analysis and assessment of verbal memory function to investigate relationships between these factors in a sample of 170 healthy volunteers (age range 46–77 years).</p> <p>Methods</p> <p>Brain morphometric analysis was performed with the automated segmentation work-flow implemented in FreeSurfer. Genetic analysis of the APOE genotype was determined with polymerase chain reaction (PCR) on DNA from whole-blood. All individuals were subjected to extensive neuropsychological testing, including the California Verbal Learning Test-II (CVLT). To obtain robust and easily interpretable relationships between explanatory variables and verbal memory function we applied the recent method of conditional inference trees in addition to scatterplot matrices and simple pairwise linear least-squares regression analysis.</p> <p>Results</p> <p>APOE genotype had no significant impact on the CVLT results (scores on long delay free recall, CVLT-LD) or the ICV-normalized hippocampal volumes. Hippocampal volumes were found to decrease with age and a right-larger-than-left hippocampal asymmetry was also found. These findings are in accordance with previous studies. CVLT-LD score was shown to correlate with hippocampal volume. Multivariate conditional inference analysis showed that gender and left hippocampal volume largely dominated predictive values for CVLT-LD scores in our sample. Left hippocampal volume dominated predictive values for females but not for males. APOE genotype did not alter the model significantly, and age was only partly influencing the results.</p> <p>Conclusion</p> <p>Gender and left hippocampal volumes are main predictors for verbal memory function in normal aging. APOE genotype did not affect the results in any part of our analysis.</p

On Radio-Frequency Spectrum Management

This article review lessons learned from the uses of radio-frequency (RF) spectrum at national and international scales. Its main purpose is to stimulate debate on how to allow new wireless systems to operate, and to reduce the chronic apparent shortage of RF spectrum. The article aims at a better understanding of the mechanisms behind spectrum management and their pertinence to the public interest. The main contributions if the article are: • Considering RF spectrum management as a construct that structures radio services and, at the same time, distributes wealth and power; • Highlighting major doctrines of RF spectrum management; • Promoting spectrum management directly by its users; • Promoting cooperation and transparency. The several parts of the paper include the evolution of spectrum exploitation, and a foreseeable future by taking a closer look at major dilemmas and challenges. The paper ends with general comments and conclusions

COST Action 280 “Propagation Impairment Mitigation for Millimetre Wave Radio Systems”

wireless access system

Chemical analyses from sediment cores of giant Troll gas field in the Norwegian North Sea

Acoustic imaging has revealed more than 7000 pockmarks on the seafloor above the Troll East gas field in the Norwegian North Sea. We present the first comprehensive study conducted on one of the World's largest pockmark fields complementing the acoustic data with extensive sampling, geochemical and petrographical studies. Specifically, we aimed at detecting possible active seepage still present over this vast area. The pockmarks are present as isolated structures, on average ~ 35 m wide and up to 100 m in size. In addition, smaller satellite pockmarks surround some of the pockmarks. In contrast to the muddy surroundings, parts of the investigated pockmarks contain laterally extensive carbonate deposits or meter sized carbonate blocks. These blocks provide shelter to abundant colonies of benthic megafauna. The carbonate blocks are comprised of micritic Mg-calcite and calcite, micritic aragonite, and botryoidal aragonite. Framboidal pyrite is also commonly present. Carbon isotopic values of the carbonates are 13C-depleted (d13C as low as - 59.7per mil) and with d18O up to 4.5per mil, indicating a methanogenic origin, possibly linked to gas hydrate dissociation. Pore water extracted from shallow cores from the centre and the flanks of the pockmarks show similar Cl and SO4 profiles as the reference cores outside the pockmarks, ruling out active methane seepage. This conclusion is also supported by seafloor video observations that did not reveal any evidence of visual fluid seepage, and by the absence of microbial mats and by the fact that the carbonate blocks are exposed on the seafloor and party oxidized on the surface. We conclude that methane seepage formed this extensive gas field following to gas hydrate dissociation