Characteristics of natural remanent magnetization of Nova Petropolis iron meteorite (II)

Nova Petropolis (medium octahedrite, IIIA) was studied magnetically focusing on the acquisition mechanism of natural remanent magnetization (NRM). Thermomagnetic properties, hysteresis properties, NRM stabilities and the study of fine magnetic structures by north seeking bacteria (NSB) were examined. The sample consists of polycrystalline kamacite, taenite and cloudy taenite, while tetrataenite is absent. The NRM directions scattered widely among subsamples, but each subsample was extremely stable against AF demagnetization up to 100mT. The S pole alignments observed by NSB were not parallel completely with the crystallographic axis of kamacite. In order to understand the stable NRM of Nova Petropolis, we must consider the magnetic domains that were reconfigured and stabilized due to deformation by hyper-velocity shocks

Prefrailty and chronic morbidity in the youngest old: an insight from the Lausanne Cohort Lc65+.

OBJECTIVES: To estimate the prevalence of prefrailty, frailty, comorbidity, and disability in the youngest old and to identify chronic diseases associated with individual frailty criteria. DESIGN: Population-based cohort study of noninstitutionalized elderly adults at baseline; cross-sectional analysis. SETTING: Lausanne, Switzerland. PARTICIPANTS: One thousand two hundred eighty-three individuals with complete data on frailty, aged 65 to 70 (58.5% women). MEASUREMENTS: Frailty was assessed according to an adaptation of Fried's criteria (shrinking, weakness, exhaustion, slowness, and low activity, three criteria needed for the diagnosis of frailty, 1 to 2 for prefrailty). Other outcomes were diseases diagnosed by a doctor (≥ 2 chronic diseases: comorbidity) and limitations in activities of daily living (ADLs, basic and instrumental). RESULTS: At baseline, of 1,283 participants 71.1% were classified as nonfrail, 26.4% as prefrail, and 2.5% as frail. The proportion of women increased across these three groups (56.5%, 62.8%, and 71.9%, respectively; P = .01), as did the proportion of individuals with one or more chronic diseases (68.0%, 82.8%, and 90.6%, respectively; P < .001) and the proportion with basic or instrumental ADL disability (1.6%, 10.3%, and 59.4%, respectively; P < .001). Weakness (low grip strength) was the most frequent criterion (14.3%). Prefrail participants had significantly more comorbidity and ADL disability than nonfrail participants (P < .001). When present in isolation, weakness was associated with two to three times greater prevalence of coronary heart disease, other heart diseases, diabetes mellitus, and arthritis. Similarly, a significant association was identified between exhaustion and depression. CONCLUSION: Prefrailty is common in the youngest old. The most prevalent frailty criterion is weakness, which is associated with cardiovascular diseases. Longitudinal studies of the evolution of prefrailty should explore the role of potential interactions between individual frailty criteria and specific chronic diseases

Complex networks: new trends for the analysis of brain connectivity

Today, the human brain can be studied as a whole. Electroencephalography, magnetoencephalography, or functional magnetic resonance imaging techniques provide functional connectivity patterns between different brain areas, and during different pathological and cognitive neuro-dynamical states. In this Tutorial we review novel complex networks approaches to unveil how brain networks can efficiently manage local processing and global integration for the transfer of information, while being at the same time capable of adapting to satisfy changing neural demands.Comment: Tutorial paper to appear in the Int. J. Bif. Chao

Application of COMPOCHIP Microarray to Investigate the Bacterial Communities of Different Composts

A microarray spotted with 369 different 16S rRNA gene probes specific to microorganisms involved in the degradation process of organic waste during composting was developed. The microarray was tested with pure cultures, and of the 30,258 individual probe-target hybridization reactions performed, there were only 188 false positive (0.62%) and 22 false negative signals (0.07%). Labeled target DNA was prepared by polymerase chain reaction amplification of 16S rRNA genes using a Cy5-labeled universal bacterial forward primer and a universal reverse primer. The COMPOCHIP microarray was applied to three different compost types (green compost, manure mix compost, and anaerobic digestate compost) of different maturity (2, 8, and 16 weeks), and differences in the microorganisms in the three compost types and maturity stages were observed. Multivariate analysis showed that the bacterial composition of the three composts was different at the beginning of the composting process and became more similar upon maturation. Certain probes (targeting Sphingobacterium, Actinomyces, Xylella/Xanthomonas/ Stenotrophomonas, Microbacterium, Verrucomicrobia, Planctomycetes, Low G + C and Alphaproteobacteria) were more influential in discriminating between different composts. Results from denaturing gradient gel electrophoresis supported those of microarray analysis. This study showed that the COMPOCHIP array is a suitable tool to study bacterial communities in composts

Magnetic properties of lamellar tetrataenite in Toluca iron meteorite

Magnetic studies were conducted using lamellar tetrataenite extracted from the Toluca octahedrite by a diluted HCl etching technique. Natural remanent magnetization (NRM) in the lamellae is very stable against AF demagnetization and is quite intense, ranging from 2.58 to 37.42×(10)^ Am^2/kg. This NRM is completely demagnetized at about 550℃ of temperature. The most characteristic change in magnetic properties on heating up to about 550℃ is a significant decrease in magnetic coercivity. This observation is consistent with the results obtained from chondrites. The paramagnetic component in lamellar tetrataenite, which is estimated by Mossbauer spectrum analyses, was not detected by conventional magnetic studies

Échange scientifique avec la France. Épisodes significatifs

Note portant sur l’auteur Les traits caractéristiques essentiels qui ont marqué mes quarante ans de collaboration avec la France ont été, sans aucun doute, le fruit de mes années de formation post-universitaire au laboratoire Curie à Paris. Ayant achevé mes études de chimie à ce qui était alors l’Université du Brésil, je suis arrivé à Paris en 1948. Quelques mois plus tard, j’étais accepté par le couple Irène et Frédéric Joliot-Curie, comme stagiaire au Laboratoire Curie de l’Institut du radi..