The bend stiffness of S-DNA

We formulate and solve a two-state model for the elasticity of nicked, double-stranded DNA that borrows features from both the Worm Like Chain and the Bragg--Zimm model. Our model is computationally simple, and gives an excellent fit to recent experimental data through the entire overstretching transition. The fit gives the first value for the bending stiffness of the overstretched state as about 10 nm*kbt, a value quite different from either B-form or single-stranded DNA.Comment: 7 pages, 1 figur

The Experiences of Mental Illness and Addiction among Men and Women with Co-occurring Disorders

The study presented used empirical phenomenological methods to gain insight into the experiences of chemical dependence and mental illness among men and women with co-occurring disorders. The literature review discussed issues concerning: gender with the self-construal, traditional gender norms, and gender as a factor in the co-occurring disorder population. The results of this study include the following themes: catalysts for change, positive and negative self-concept, substance use as a means of self-medication, and therapeutic factors. Implications for the counseling profession, and implications for further research were discussed

Off-lattice Monte Carlo Simulation of Supramolecular Polymer Architectures

We introduce an efficient, scalable Monte Carlo algorithm to simulate cross-linked architectures of freely-jointed and discrete worm-like chains. Bond movement is based on the discrete tractrix construction, which effects conformational changes that exactly preserve fixed-length constraints of all bonds. The algorithm reproduces known end-to-end distance distributions for simple, analytically tractable systems of cross-linked stiff and freely jointed polymers flawlessly, and is used to determine the effective persistence length of short bundles of semi-flexible worm-like chains, cross-linked to each other. It reveals a possible regulatory mechanism in bundled networks: the effective persistence of bundles is controlled by the linker density.Comment: 4 pages, 4 figure

Evaluation of SIR-A space radar for geologic interpretation: United States, Panama, Colombia, and New Guinea

Comparisons between LANDSAT MSS imagery, and aircraft and space radar imagery from different geologic environments in the United States, Panama, Colombia, and New Guinea demonstrate the interdependence of radar system geometry and terrain configuration for optimum retrieval of geologic information. Illustrations suggest that in the case of space radars (SIR-A in particular), the ability to acquire multiple look-angle/look-direction radar images of a given area is more valuable for landform mapping than further improvements in spatial resolution. Radar look-angle is concluded to be one of the most important system parameters of a space radar designed to be used for geologic reconnaissance mapping. The optimum set of system parameters must be determined for imaging different classes of landform features and tailoring the look-angle to local topography

Infrared Surface Brightness Distances to Cepheids: a comparison of Bayesian and linear-bisector calculations

We have compared the results of Bayesian statistical calculations and linear-bisector calculations for obtaining Cepheid distances and radii by the infrared surface brightness method. We analyzed a set of 38 Cepheids using a Bayesian Markov Chain Monte Carlo method that had been recently studied with a linear-bisector method. The distances obtained by the two techniques agree to 1.5 \pm 0.6% with the Bayesian distances being larger. The radii agree to 1.1% \pm 0.7% with the Bayesian determinations again being larger. We interpret this result as demonstrating that the two methods yield the same distances and radii. This implies that the short distance to the LMC found in recent linear-bisector studies of Cepheids is not caused by deficiencies in the mathematical treatment. However, the computed uncertainties in distance and radius for our dataset are larger in the Bayesian calculation by factors of 1.4-6.7. We give reasons to favor the Bayesian computations of the uncertainties. The larger uncertainties can have a significant impact upon interpretation of Cepheid distances and radii obtained from the infrared surface brightness method.Comment: 27 pages with 9 figure

Social Circuits: Peptidergic Regulation of Mammalian Social Behavior

Mammals have developed patterns of social relationships that enhance the survival of individuals and maximize the reproductive success of species. Although social stimuli and social responses are highly complex, recent studies are providing substantial insights into their neural substrates. Neural pathways employing the nonapeptides vasopressin and oxytocin play a particularly prominent role both in social recognition and the expression of appropriate social responses. New insights into social neuroscience are discussed, along with the relevance of this rapidly developing field to human relationships and disease processes

Automated myocardial perfusion from coronary X-ray angiography

The purpose of our study is the evaluation of an algorithm to determine the physiological relevance of a coronary\ud lesion as seen in a coronary angiogram. The aim is to extract as much as possible information from a standard\ud coronary angiogram to decide if an abnormality, percentage of stenosis, as seen in the angiogram, results in\ud physiological impairment of the blood supply of the region nourished by the coronary artery. Coronary angiography,\ud still the golden standard, is used to determine the cause of angina pectoris based on the demonstration\ud of an important stenose in a coronary artery. Dimensions of a lesion such as length and percentage of narrowing\ud can at present easily be calculated by using an automatic computer algorithm such as Quantitative Coronary\ud Angiography (QCA) techniques resulting in just anatomical information ignoring the physiological relevance of\ud the lesion. In our study we analyze myocardial perfusion images in standard coronary angiograms in rest and\ud in artificial hyperemic phases, using a drug e.g. papaverine intracoronary. Setting a Region of Interest (ROI) in\ud the angiogram without overlying major vessels makes it possible to calculate contrast differences as a function of\ud time, so called time-density curves, in the basal and hyperemic phases. In minimizing motion artifacts, end diastolic\ud images are selected ECG based in basal and hyperemic phase in an identical ROI in the same angiographic\ud projection. The development of new algorithms for calculating differences in blood supply in the region as set\ud are presented together with the results of a small clinical case study using the standard angiographic procedur

CAD of myocardial perfusion

Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol