Distribution of resonance widths and dynamics of continuum coupling.

We analyze the statistics of resonance widths in a many-body Fermi system with open decay channels. Depending on the strength of continuum coupling, such a system reveals growing deviations from the standard chi-square (Porter-Thomas) width distribution. The deviations emerge from the process of increasing interaction of intrinsic states through common decay channels; in the limit of perfect coupling this process leads to the superradiance phase transition. The width distribution depends also on the intrinsic dynamics (chaotic versus regular). The results presented here are important for understanding the recent experimental data concerning the width distribution for neutron resonances in nuclei.

Eta/s ratio in finite nuclei.

Experiments at the Relativistic Heavy Ion Collider (RHIC) suggest that the state of matter produced in the experiments has a low shear-viscosity to entropy-density ratio eta/s. We ask here the following question: what is this ratio in the usual finite nuclei at low temperature? We use the experimental and theoretical results for the widths of giant vibrational states in nuclei in order to calculate the above ratio. We find that the values of eta/s are not very different from the ones found in the RHIC experiments.

Brain MRI of nasal MOG therapeutic effect in relapsing-progressive EAE.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) considered to be a T cell-mediated autoimmune disease. Mucosally administered antigens induce regulatory T cells that secrete anti-inflammatory cytokines at the anatomic site where the mucosally administered Ag is located. We have previously reported in a mouse model of stroke that nasal treatment with MOG35-55 peptide reduces ischemic infarct size and improves behavior, by inducing IL-10-secreting T cells. We have also demonstrated that an experimental autoimmune encephalomyelitis (EAE) model in non-obese diabetic (NOD) mice leads to a relapsing progressive disease and that brain lesions can be visualized noninvasively by magnetic resonance imaging (MRI). Here, we investigated whether nasal treatment with 25µg of MOG35-55 after the first attack affects clinical progression and MRI outcome in the NOD model. We found that nasal MOG35-55 treatment administered three times after the first attack and then weekly reduced both the peak clinical disease score and clinical score during remission. Pathology revealed less infiltration of cells and reduction in white-matter damage as measured by Luxol blue staining in treated animals. This model is unique in that there are lesions in the corpus callosum, external capsule, fimbria, internal capsule and thalamus, which is analogous to what is observed in MS. MRI of individual animals using fractional anisotropy (FA) and T1-gadolinum (T1-Gd) imaging was able to identify lesions in all of these anatomic areas, and we found lower levels of brain pathology by MRI in treated mice with both methods. Our results indicate a beneficial effect of nasal MOG on relapsing-progressive EAE and demonstrate that non-invasive MRI imaging may be used to monitor treatment of ongoing disease in this model for testing new therapies for MS.

Dipyridamole cardiac imaging.

Dipyridamole cardiac imaging is a useful alternative technique to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole is still in the investigational phase, while oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow (due to coronary vasodilation) which is in excess of the increase in myocardial oxygen consumption and cardiac output. The disparity in the increase in coronary blood flow relative to the cardiac output results in an increase in myocardial thallium activity and an increase in the myocardial/background activity ratio. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg, and of the oral dose it is 300 to 400 mg, although higher doses may be necessary in some patients. Analysis of the thallium images has been to a large extent based on visual inspection of the planar images. Delayed images are helpful to establish the nature of the perfusion abnormalities (transient or fixed). The process of redistribution is based on disparate rates of washout from the normal and abnormal zones. The sensitivity and specificity of dipyridamole thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole two-dimensional echocardiography has also been used in the detection of coronary artery disease; transient (new or worsening of preexisting) wall motion abnormalities have been found to be a specific marker of coronary artery disease. Transmural as well as regional coronary steal phenomena have been postulated as the mechanism for dipyridamole-induced regional wall motion abnormalities. Compared to exercise two-dimensional echocardiography, dipyridamole echocardiography provides high-quality studies and in higher proportions of patients. The results of dipyridamole thallium imaging have also been extremely important in identifying high-risk patients after acute myocardial infarction or patients with peripheral vascular disease undergoing elective vascular surgery; the presence of a dipyridamole-induced perfusion abnormality identifies patients at high risk for future cardiac events. Thus, dipyridamole cardiac imaging is helpful in the diagnosis of coronary artery disease and in risk stratification.