Correlations of projectile like fragments in heavy ion reactions at Fermi energy

Correlations between pairs of projectile-like fragments, emitted by the system ${^{16}O}+{^{197}Au}$ at the laboratory bombarding energy of 515 MeV, have been studied under two stipulated conditions: (1) at least one member of the pair is emitted at an angle less than the grazing angle for the system, (2) both the members of the pair are emitted at angles larger than the grazing angle. A surprisingly large difference, by more than an order of magnitude, is found between the correlations for the two cases. This observation could be explained on the basis of a simple semi-classical break up model. Further analysis of the variation of the charge correlation function with the difference in the nuclear charges of the correlated pair showed trends which are consistent with an "inelastic break up process", in which the projectile breaks up at the radius of contact, in such a way that, one fragment (preferably the lighter) is emitted to one side within the grazing angle, while the other orbits around the target nucleus for a while and emerges on the other side, at a negative scattering angle, much like in a deep inelastic scattering.Comment: 19 pages, 12 figures accepted by Eurp. Physics Journal

Lipid Bilayer Composition Affects Transmembrane Protein Orientation and Function

Sperm membranes change in structure and composition upon ejaculation to undergo capacitation, a molecular transformation which enables spermatozoa to undergo the acrosome reaction and be capable of fertilization. Changes to the membrane environment including lipid composition, specifically lipid microdomains, may be responsible for enabling capacitation. To study the effect of lipid environment on proteins, liposomes were created using lipids extracted from bull sperm membranes, with or without a protein (Na+ K+-ATPase or α-amylase). Protein incorporation, function, and orientation were determined. Fluorescence resonance energy transfer (FRET) confirmed protein inclusion in the lipid bilayer, and protein function was confirmed using a colourometric assay of phosphate production from ATP cleavage. In the native lipid liposomes, ATPase was oriented with the β subunit facing the outer leaflet, while changing the lipid composition to 50% native lipids and 50% exogenous lipids significantly altered this orientation of Na+ K+-ATPase within the membranes

Seroprevalence of Toxoplasma gondii in German swine herds

The protozoan parasite Toxoplasma (T) gondii is prevalent worldwide and 1s found in a wide range of warm-blooded hosts mcluding humans. Raw and undercooked pork con taming tissue cysts is an important cause of the T. gondii- infection in humans. The aim of our study was to investigate the occurence of T. gondii-antibodies in German swine herds

Assessment of radiographic screen-film systems: a comparison between the use of a microdensitometer and a drum film digitiser

A high-end drum film digitiser (Tango, Germany) and a calibrated linear microdensitometer developed by PTB were used to assess the modulation transfer function (MTF) and the noise power spectra (NPS) of 3 mammographic screen film systems at optical density levels of 0.8, 1.5 and 2.5. The use of a drum scanner to assess MTF and NPS data appears to be adequate but requires an appropriate characterisation of the scanner to verify its internal noise level and its MTF. It is further necessary to calibrate the scanner output in terms of visual diffuse optical densities. Processing of two-dimensional digital data of grating images need to be more strictly defined for accurate MTF measurements of screen-film systems. Nevertheless, even now it seems to be feasible to use commercially available high-end and well calibrated scanners to assess screen film systems. This is especially important for quality assurance purposes because important parameters of screen film systems such like MTF and NPS can now be determined without using sophisticated microdensitometers which are not commercially availabl

A reassessment of Antarctic plateau reactive nitrogen based on ANTCI 2003 airborne and ground based measurements

The first airborne measurements of nitric oxide (NO) on the Antarctic plateau have demonstrated that the previously reported elevated levels of this species extend well beyond the immediate vicinity of South Pole. Although the current database is still relatively weak and critical laboratory experiments are still needed, the findings here suggest that the chemical uniqueness of the plateau may be substantially greater than first reported. For example, South Pole ground-based findings have provided new evidence showing that the dominant process driving the release of nitrogen from the snowpack during the spring/summer season (post-depositional loss) is photochemical in nature with evaporative processes playing a lesser role. There is also new evidence suggesting that nitrogen, in the form of nitrate, may undergo multiple recycling within a given photochemical season. Speculation here is that this may be a unique property of the plateau and much related to its having persistent cold temperatures even during summer. These conditions promote the efficient adsorption of molecules like HNO3 (and very likely HO2NO2) onto snow-pack surface ice where we have hypothesized enhanced photochemical processing can occur, leading to the efficient release of NOx to the atmosphere. In addition, to these process-oriented tentative conclusions, the findings from the airborne studies, in conjunction with modeling exercises suggest a new paradigm for the plateau atmosphere. The near-surface atmosphere over this massive region can be viewed as serving as much more than a temporary reservoir or holding tank for imported chemical species. It defines an immense atmospheric chemical reactor which is capable of modifying the chemical characteristics of select atmospheric constituents. This reactor has most likely been in place over geological time, and may have led to the chemical modulation of some trace species now found in ice cores. Reactive nitrogen has played a critical role in both establishing and in maintaining this reactor. © 2007 Elsevier Ltd. All rights reserved

Expanding our conceptualization of excessive worry and GAD : the role of fear and avoidance of emotional experiences

Fear of emotional responding and experiential avoidance may play an important role in excessive worry and generalized anxiety disorder (GAD). The goal of the first study was to replicate previous research findings by investigating the role of fear and avoidance of emotional experiences in problematic worry and GAD. Moreover, the study served as an extension of previous research by contrasting the relationship between fear and avoidance of emotional responding and excessive worry with constructs already linked to worry and GAD, such as intolerance of uncertainty. Findings from a nonclinical sample indicated that fear of emotions, in particular fear of anxiety, and experiential avoidance were significantly related to excessive worry, which is the defining feature of GAD. Worry was also highly associated with intolerance of uncertainty. Additional analyses revealed that fear of anxiety, experiential avoidance, and intolerance of uncertainty, all made significant and unique contributions to the prediction of worry. Finally, the results suggested that the tendency to fear and avoid emotional experiences was related to GAD diagnostic criteria. The goal of the second study was to clarify the role of fear of anxiety in worry by assessing whether the experimental manipulation of fear of anxiety affected worry level. The study also assessed the combined effects of fear of anxious responding and intolerance of uncertainty on level of worry by grouping participants according to their tolerance for uncertainty. The results indicated that participants whose fear of anxiety was increased showed higher levels of worry compared to participants whose fear of anxiety was decreased. This finding provides preliminary support for the causal role of fear of anxiety in worry. Moreover, the results showed that increased fear of anxiety in combination with an intolerance for uncertainty led to the highest levels of worry, which suggests that these constructs have an additive effect on worry. The findings from the present research lend support to the integration of new conceptualizations of psychopathology with existing models of excessive worry, which could ultimately increase treatment efficacy for GAD