Increased cortical curvature reflects white matter atrophy in individual patients with early multiple sclerosis

AbstractObjectiveWhite matter atrophy occurs independently of lesions in multiple sclerosis. In contrast to lesion detection, the quantitative assessment of white matter atrophy in individual patients has been regarded as a major challenge. We therefore tested the hypothesis that white matter atrophy (WMA) is present at the very beginning of multiple sclerosis (MS) and in virtually each individual patient. To find a new sensitive and robust marker for WMA we investigated the relationship between cortical surface area, white matter volume (WMV), and whole-brain-surface-averaged rectified cortical extrinsic curvature. Based on geometrical considerations we hypothesized that cortical curvature increases if WMV decreases and the cortical surface area remains constant.MethodsIn total, 95 participants were enrolled: 30 patients with early and advanced relapsing–remitting MS; 30 age-matched control subjects; 30 patients with Alzheimer's disease (AD) and 5 patients with clinically isolated syndrome (CIS).Results29/30 MS and 5/5 CIS patients showed lower WMV than expected from their intracranial volume (average reduction 13.0%, P<10−10), while the cortical surface area showed no significant differences compared with controls. The estimated WMV reductions were correlated with an increase in cortical curvature (R=0.62, P=0.000001). Discriminant analysis revealed that the curvature increase was highly specific for the MS and CIS groups (96.7% correct assignments between MS and control groups) and was significantly correlated with reduction of white matter fractional anisotropy, as determined by diffusion tensor imaging and the Expanded Disability Status Scale. As expected by the predominant gray and WM degeneration in AD, no systematic curvature increase was observed in AD.ConclusionWhole-brain-averaged cortical extrinsic curvature appears to be a specific and quantitative marker for a WMV–cortex disproportionality and allows us to assess “pure” WMA without being confounded by intracranial volume. WMA seems to be a characteristic symptom in early MS and can already occur in patients with CIS and should thus be considered in future MS research and clinical studies

The Lantern Vol. 64, No. 2, Spring 1997

• Year\u27s End, with Resolutions • Addicted • Muerte, Carlos • Motions • At the Wyeth Gallery • Between Contexts • I\u27m Allowed (and More Nonsense) • Wall and Piece • Timekeeper\u27s Workspace • The Process • Second Sex: A Portrait of the Artist as a Woman • On the Side of the Road • Joe • To Matthew Arnold • A Deep Sleep on Hydrocodone • Madness of a Night • Return • The Sudden Grave • A Farce • Twists of Fur • Ambiguity • The Odor of Continuums • My Father\u27s Daughter • The Meaning of Life • I Aim to Tell • Nobody\u27s Fanhttps://digitalcommons.ursinus.edu/lantern/1150/thumbnail.jp

Self ignition of hydrogen-air mixtures with inclined porthole injection in supersonic flows

Experiments were performed in the T4 shock tunnel to investigate the self ignition of hydrogen in a supersonic air stream. Hydrogen was injected into the flow over an inclined flat plate for oncoming Mach numbers of 7.9 to 8.0. The nozzle-supply enthalpy was kept between 3.1 and 3.4 MJ/kg and two different pressure levels were used in the tests. Measurements of surface pressures were used to infer the location of ignition but only small pressure increases were obtained when combustion occurred. Therefore multiple tests at nominally the same condition were used so that statistical methods could be used to identify the ignition lengths. The ignition lengths of the hydrogen air mixture directly behind a strong leading edge shock indicate that Pergament's method is able to predict the ignition length to within 35% for the observed autoignition over the range of conditions tested

Output dynamics of the G7 countries--stochastic trends and cyclical movements

Using a time series framework, the paper studies the interactions of the annual real per capita GDP data of the G7 countries. Evidence is found of six common nonstationary processes behind the international output dynamics. In addition, there is evidence for the existence of a common business cycle among these countries. The trend and cycle components of each output series are obtained with a procedure that accounts for the presence of both the common nonstationary and cyclical factors. It is found that the relative variability and the correlation of the trend and cycle components are not similar across the G7 countries.