Aggregated motion estimation for real-time MRI reconstruction

Real-time magnetic resonance imaging (MRI) methods generally shorten the measuring time by acquiring less data than needed according to the sampling theorem. In order to obtain a proper image from such undersampled data, the reconstruction is commonly defined as the solution of an inverse problem, which is regularized by a priori assumptions about the object. While practical realizations have hitherto been surprisingly successful, strong assumptions about the continuity of image features may affect the temporal fidelity of the estimated images. Here we propose a novel approach for the reconstruction of serial real-time MRI data which integrates the deformations between nearby frames into the data consistency term. The method is not required to be affine or rigid and does not need additional measurements. Moreover, it handles multi-channel MRI data by simultaneously determining the image and its coil sensitivity profiles in a nonlinear formulation which also adapts to non-Cartesian (e.g., radial) sampling schemes. Experimental results of a motion phantom with controlled speed and in vivo measurements of rapid tongue movements demonstrate image improvements in preserving temporal fidelity and removing residual artifacts.Comment: This is a preliminary technical report. A polished version is published by Magnetic Resonance in Medicine. Magnetic Resonance in Medicine 201

Horizontal Stratification in Access to Danish University Programmes

In this paper, we use register data to examine horizontal stratification within university institutions and university fields of study in Denmark, a country that has experienced a reduction of the social class gap in access to higher education. First, we argue that it is important to use a relatively detailed classification of parents’ occupations to determine how students are endowed with different forms of capital, even when their parents would typically be characterised as belonging to the same social group. Second, we distinguish among disciplines and among university institutions to explain the dynamics of horizontal stratification in the Danish university system. Using unique and exhaustive register data, including all higher education institutions and the entire 1984 cohort as of the age of 24, we uncover distinct differences in the magnitude and type of horizontal stratification in different fields of study and university institutions. Most importantly, we find distinct patterns of horizontal stratification by field of study and parental occupation that would have remained hidden had we used more aggregated classifications for field of study and social origin.</jats:p

Geophysical Applications for Arctic/Subarctic Transportation Planning

This report describes a series of geophysical surveys conducted in conjunction with geotechnical investigations carried out by the Alaska Department of Transportation and Public Facilities. The purpose of the study was to evaluate the value of and potential uses for data collected via geophysical techniques with respect to ongoing investigations related to linear infrastructure. One or more techniques, including direct-current resistivity, capacitive-coupled resistivity, and ground-penetrating radar, were evaluated at sites in continuous and discontinuous permafrost zones. Results revealed that resistivity techniques adequately differentiate between frozen and unfrozen ground, and in some instances, were able to identify individual ice wedges in a frozen heterogeneous matrix. Capacitive-coupled resistivity was found to be extremely promising due to its relative mobility as compared with direct-current resistivity. Ground-penetrating radar was shown to be useful for evaluating the factors leading to subsidence in an existing road. Taken as a whole, the study results indicate that supplemental geophysical surveys may add to the quality of a geotechnical investigation by helping to optimize the placement of boreholes. Moreover, such surveys may reduce the overall investigation costs by reducing the number of boreholes required to characterize the subsurface

Screening asylum seekers in Denmark for torture using a structured questionnaire

The United Nations Committee against Torture recommends systematic torture screening throughout the asylum process.&nbsp;&nbsp; The goal of this study is to evaluate the introduction of a structured questionnaire, coding for torture according to the definition from United Nations Convention Against Torture (UNCAT). This screening for torture is now an integrated part of the medical reception of newly arrived asylum seekers The screening was carried through during a 2 years period as a part of the routine health screening, and alleged torture victims were referred to further medical examination and offered assistance to carry information about the torture to the Immigration Service. The participation rate was 85.2%, and torture was reported&nbsp;among 27.8% of the males, with a mean of 21.2% among both sexes. Key words: Torture, screening, questionnaire, asylum seekers, UNCA