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Isometric force-related functional magnetic resonance imaging (fMRI) signals from primary sensorimotor cortex were investigated by imaging during a sustained finger flexion task at a number of force levels related to maximum voluntary contraction. With increasing levels of force, there was an increase in the extent along the central sulcus from which a fMRI(More)
Functional magnetic resonance imaging (fMRI) studies of the human motor system have commonly used movement paradigms which contain a dynamic component; however, the relationship between the fMRI signal for motor tasks with and without a dynamic component is not known. We have investigated the relationship between the fMRI signal during a static finger(More)
BACKGROUND AND PURPOSE Mapping of eloquent cortex using blood-oxygen-level-dependent (BOLD) contrast functional MRI (fMRI) has rapidly gained acceptance as part of the evaluation of patients being considered for neurosurgical interventions. The BOLD signal measures local susceptibility in the blood, which can change during periods of increased neuronal(More)
To investigate risk factors for sporadic infection with Giardia lamblia acquired in the United Kingdom, we conducted a matched case-control study in southwest England in 1998 and 1999. Response rates to a postal questionnaire were 84% (232/276) for cases and 69% (574/828) for controls. In multivariable analysis, swallowing water while swimming (p<0.0001,(More)
A significant role in the planning and preparation for voluntary movement has been ascribed to secondary motor areas located on the medial wall of the cerebral hemispheres, and in particular to the supplementary motor area (SMA). Within the SMA, rostral and caudal subdivisions have been described, and differential roles have been attributed to these regions(More)
BACKGROUND Between roughly 500 BCE and 300 BCE, three distinct regions, the Yangtze and Yellow River Valleys, the Eastern Mediterranean, and the Ganges Valley, saw the emergence of highly similar religious traditions with an unprecedented emphasis on self-discipline and asceticism and with "otherworldly," often moralizing, doctrines, including Buddhism,(More)
Assimilation of carbon-14 labeled bicarbonate into photosynthetic products was measured at four stations in the Southern Ocean. Phytoplankton populations incorporated as much as 80 percent of the fixed carbon into lipid under conditions of low temperatures (-0.2 degrees to -1.8 degrees C) and low light intensities. At higher temperatures (+0.3 degrees to(More)
When a ruling elite is unable to commit to future growth-promoting policies, it may cede political power to a broader segment of the public, as in North and Weingast (1989). Alternatively, as we show in this paper, commitment may be achieved by moving in the opposite direction: installing a single authoritarian ruler who favors growth-promoting policies.(More)