The Human Connectome Project's neuroimaging approach

Noninvasive human neuroimaging has yielded many discoveries about the brain. Numerous methodological advances have also occurred, though inertia has slowed their adoption. This paper presents an integrated approach to data acquisition, analysis and sharing that builds upon recent advances, particularly from the Human Connectome Project (HCP). The 'HCP-style' paradigm has seven core tenets: (i) collect multimodal imaging data from many subjects; (ii) acquire data at high spatial and temporal resolution; (iii) preprocess data to minimize distortions, blurring and temporal artifacts; (iv) represent data using the natural geometry of cortical and subcortical structures; (v) accurately align corresponding brain areas across subjects and studies; (vi) analyze data using neurobiologically accurate brain parcellations; and (vii) share published data via user-friendly databases. We illustrate the HCP-style paradigm using existing HCP data sets and provide guidance for future research. Widespread adoption of this paradigm should accelerate progress in understanding the brain in health and disease

Interfacing the DIGICO flux-gate spinner magnetometer to an APPLE IIe microcomputer

International audienc

The shape of the geomagnetic field through the last 8,500 years over part of the northern hemisphere

Regional type curves depicting secular variations of declination and inclination through the last 10,000 calendar years constructed for north-western Europe (356° E, 55° N) and east-central North America (270° E, 46° N) by stacking palaeomagnetic data derived from lake sediment cores are described and analysed. The spectral content and phase relationships of the two pairs of curves show that they have a complex origin with both drifting and standing geomagnetic sources contributing to them. The strongest evidence of drifting sources is provided by the inclination type-curves which exhibit maximum correlation for a phase shift of ~650 years suggestive of westward drift at a rate of about 0.13 degrees a year. At the same time, comparison of the declination type-curves strongly suggests that waxing and waning standing sources were dominant. We show that the difference in relative importance of drifting as compared to standing geomagnetic sources implied by the patterns of correlation deduced respectively for declination and inclination can, at least in principle, be attributed to observation point/geomagnetic source geometry by modelling the secular variation that would be produced by standing but oscillating equatorial dipoles and radial dipoles located deep within the outer core, by a pair of drifting deep-seated radial dipoles of constant intensity, and by drifting sheets of radial dipoles (taken to represent current-loops) located at shallow depth within the outer core. Each of these model sources produces secular variation curves with distinctive shapes and phase relationships. Hence, an attempt is made to identify qualitatively the types and locations of the sources which dominated the secular variations as recorded by our type-curves. One of our most important conclusions is that there appears to be a' turning-point' at ~ 4 750 years before present when the relative amplitudes of the active' standing' sources changed but the characteristics of the drifting sources appear to have remained relatively unchanged.           ARK: https://n2t.net/ark:/88439/y011535 Permalink: https://geophysicsjournal.com/article/263 &nbsp

Determination of the correlation between the electrical resistivity of non-cohesive soils and the degree of compaction

International audienceElectrical resistivity measurements provide potentially powerful tool for estimation of physical parameters of soils and materials used in earthworks and constructions like embankments and dams. The study demonstrates the correlation between the resistivity of non-cohesive soils and the degree of compaction, which is an indicator of important and possibly risks bearing hydraulic piping or tunneling. In this paper we investigate the relationship between electrical resistivity of non-cohesive soils and granulated materials used in earth-works and constructions such as road embankments, and degree of compaction. Laboratory analyses of the last parameter are time consuming and estimated using parameters such as moisture content, bulk density and porosity, the same parameters (mostly obviously porosity and moisture content and including pore water mineralization) determine electrical resistivity. In consequence, electrical resistivity is a potentially well adapted alternative method for determination of the degree of compaction. To investigate the problem, electrical resistivity survey was conducted in a laboratory using soil samples representing fine, medium and coarse sands, submitted to successive steps of compaction. The measurements were carried out in the box, which may be compared with the construction such as an embankment. Obtained resistivity values were analyzed taking into consideration electrode spacing and the physical parameters of soil at each step of compaction