AEC research and development report

Abstract: This technical report contains a comprehensive analysis of the nuclear characteristics of the SM-1 Core I. Comparison of analytical and experimental results for neutron ages and core reactivities of a variety of cases investigated shows that the MUFT III with P-1 slowing down approximation gives the best results. At startup the core reactivity and rod bank worth under various operating conditions are investigated and compared to experiment. Core lifetime was calculated to be 16.8 MWYR compared to 16.4 MWYR experimental. The temperature coefficient has been calculated and compared to experiment as function of burnup. In Appendix A, flux distribution, temperature coefficient, effective delayed neutron fraction and core life are analyzed by Dr. R. L. Murray by one and two group modified theory series expansion calculations

Coastal upwelling off Peru during normal and El Nino times, 1981-1984

Repeated conductivity, temperature, and depth (CTD) sections were made across the continental margin off Peru at 5°S and 10°S between November 1981 and May 1984, i.e., before, during, and after El Nino of 1982-1983. Coastal sea level at Paita (5°S) and Callao (12°S) began to rise in early October 1982 and returned to normal in July 1983. Coastal winds, which are normally favorable for upwelling, remained normal during October 1982; between November 1982 and May 1983 they were weaker than normal at Talara and Paita (5°S) but stronger than normal at Callao (12°S). Between mid-March and mid-April 1983, winds at 5°S were very weak or even unfavorable for upwelling. Repeated CTD sections at 5°S show signs of active upwelling (a negative onshore surface temperature gradient and upward sloping isotherms near the coast) whenever local winds were favorable for upwelling, but not when winds were calm or unfavorable. At 10°S, winds remained favorable for upwelling throughout El Nino. At both 5°S and 10°S, the apparent source depth of upwelling waters, 50-100 m, remained the same before, during, and after El Nino; this layer is normally below the thermocline, but during El Nino it was at the top of the depressed thermocline. The upwelling that occurred during El Nino resulted only in the upwelling of warm, nutrient-poor waters. In May 1983, a CTD section at 10°S indicated that upwelling had ceased there in spite of continued strong, upwelling-favorable winds; this cessation of upwelling is attributed to an alongshore pressure gradient that persisted from mid-March to mid-June 1983, causing onshore geostrophic flow to balance the wind-driven offshore flow in the surface layer

Current measurements off the west coast of South America: November 1981 - March 1985

Several current meter moorings were deployed over the continental margin of Peru along 5° and 10°S to study the Peru current system. The observation period from November 1981 to March 1985 covered the occurrence of El Nino 1982-83. This report presents the six-hourly low-passed data sets of each mooring. Progressive vector diagrams, stick plots and time series of the east- and northward current component, temperature and pressure are shown. Histograms of speed, direction and temperature as well as a statistical page showing means and standard deviations are also included

Numerical study of circulation on the inner Amazon Shelf

Author Posting. © Springer, 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Ocean Dynamics 58 (2008): 187-198, doi:10.1007/s10236-008-0139-4.We studied the circulation on the coastal domain of the Amazon Shelf by applying the hydrodynamic module of the Estuarine and Coastal Ocean Model and Sediment Transport - ECOMSED. The first barotropic experiment aimed to explain the major bathymetric effects on tides and those generated by anisotropy in sediment distribution. We analyzed the continental shelf response of barotropic tides under realistic bottom stress parametrization (Cd), considering sediment granulometry obtained from a faciologic map, where river mud deposits and reworked sediments areas are well distinguished, among others classes of sediments. Very low Cd values were set in the fluid mud regions off the Amapa coast (1.0 10-4 ), in contrast to values around 3:5 10-3 for coarser sediment regions off the Para coast. Three-dimensional experiments represented the Amazon River discharge and trade winds, combined to barotropic tide influences and induced vertical mixing. The quasi-resonant response of the Amazon Shelf to the M2 tide act on the local hydrodynamics by increasing tidal admittance, along with tidal forcing at the shelf break and extensive fluid mud regions. Harmonic analysis of modeled currents agreed well with analysis of the AMASSEDS observational data set. Tidal-induced vertical shear provided strong homogenization of threshold waters, which are subject to a kind of hydraulic control due to the topographic steepness. Ahead of the hydraulic jump, the low-salinity plume is disconnected from the bottom and acquires negative vorticity, turning southeastward. Tides act as a generator mechanism and topography, via hydraulic control, as a maintainer mechanism for the low-salinity frontal zone positioning. Tidally induced southeastward plume fate is overwhelmed by northwestward trade winds so that, along with background circulation, probably play the most important role on the plume fate and variability over the Amazon Shelf

Chronic non-transmural infarction has a delayed recovery of function following revascularization

<p>Abstract</p> <p>Background</p> <p>The time course of regional functional recovery following revascularization with regards to the presence or absence of infarction is poorly known. We studied the effect of the presence of chronic non-transmural infarction on the time course of recovery of myocardial perfusion and function after elective revascularization.</p> <p>Methods</p> <p>Eighteen patients (mean age 69, range 52-84, 17 men) prospectively underwent cine magnetic resonance imaging (MRI), delayed contrast enhanced MRI and rest/stress 99m-Tc-tetrofosmin single photon emission computed tomography (SPECT) before, one and six months after elective coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI).</p> <p>Results</p> <p>Dysfunctional myocardial segments (n = 337/864, 39%) were classified according to the presence (n = 164) or absence (n = 173) of infarction. Infarct transmurality in dysfunctional segments was largely non-transmural (transmurality = 31 ± 22%). Quantitative stress perfusion and wall thickening increased at one month in dysfunctional segments without infarction (p < 0.001), with no further improvement at six months. Despite improvements in stress perfusion at one month (p < 0.001), non-transmural infarction displayed a slower and lesser improvement in wall thickening at one (p < 0.05) and six months (p < 0.001).</p> <p>Conclusions</p> <p>Dysfunctional segments without infarction represent repetitively stunned or hibernating myocardium, and these segments improved both perfusion and function within one month after revascularization with no improvement thereafter. Although dysfunctional segments with non-transmural infarction improved in perfusion at one month, functional recovery was mostly seen between one and six months, possibly reflecting a more severe ischemic burden. These findings may be of value in the clinical assessment of regional functional recovery in the time period after revascularization.</p

Clinical impact and 'natural' course of uncorrected tricuspid regurgitation after implantation of a left ventricular assist device: an analysis of the European Registry for Patients with Mechanical Circulatory Support (EUROMACS)

OBJECTIVES: Data on the impact and course of uncorrected tricuspid regurgitation (TR) during left ventricular assist device (LVAD) implantation are scarce and inconsistent. This study explores the clinical impact and natural course of uncorrected TR in patients after LVAD implantation. METHODS: The European Registry for Patients with Mechanical Circulatory Support was used to identify adult patients with LVAD implants without concomitant tricuspid valve surgery. A mediation model was developed to assess the association of TR with 30-day mortality via other risk factors. Generalized mixed models were used to model the course of post-LVAD TR. Joint models were used to perform sensitivity analyses. RESULTS: A total of 2496 procedures were included (median age: 56 years; men: 83%). TR was not directly associated with higher 30-day mortality, but mediation analyses suggested an indirect association via preoperative elevated right atrial pressure and creatinine (P = 0.035) and bilirubin (P = 0.027) levels. Post-LVAD TR was also associated with increased late mortality [hazard ratio 1.16 (1.06-1.3); P = 0.001]. On average, uncorrected TR diminished after LVAD implantation. The probability of having moderate-to-severe TR immediately after an implant in patients with none-to-mild TR pre-LVAD was 10%; in patients with moderate-to-severe TR pre-LVAD, it was 35% and continued to decrease in patients with moderate-to-severe TR pre-LVAD, regardless of pre-LVAD right ventricular failure or pulmonary hypertension. CONCLUSIONS: Uncorrected TR pre-LVAD and post-LVAD is associated with increased early and late mortality. Nevertheless, on average, TR diminishes progr

Psychological Stress-Induced, IDO1-Dependent Tryptophan Catabolism: Implications on Immunosuppression in Mice and Humans

It is increasingly recognized that psychological stress influences inflammatory responses and mood. Here, we investigated whether psychological stress (combined acoustic and restraint stress) activates the tryptophan (Trp) catabolizing enzyme indoleamine 2,3-dioxygenase 1(IDO1) and thereby alters the immune homeostasis and behavior in mice. We measured IDO1 mRNA expression and plasma levels of Trp catabolites after a single 2-h stress session and in repeatedly stressed (4.5-days stress, 2-h twice a day) naïve BALB/c mice. A role of cytokines in acute stress-induced IDO1 activation was studied after IFNγ and TNFα blockade and in IDO1−/− mice. RU486 and 1-Methyl-L-tryptophan (1-MT) were used to study role of glucocorticoids and IDO1 on Trp depletion in altering the immune and behavioral response in repeatedly stressed animals. Clinical relevance was addressed by analyzing IDO1 activity in patients expecting abdominal surgery. Acute stress increased the IDO1 mRNA expression in brain, lung, spleen and Peyer's patches (max. 14.1±4.9-fold in brain 6-h after stress) and resulted in a transient depletion of Trp (−25.2±6.6%) and serotonin (−27.3±4.6%) from the plasma measured 6-h after stress while kynurenine levels increased 6-h later (11.2±9.3%). IDO1 mRNA up-regulation was blocked by anti-TNFα and anti-IFNγ treatment. Continuous IDO1 blockade by 1-MT but not RU486 treatment normalized the anti-bacterial defense and attenuated increased IL-10 inducibility in splenocytes after repeated stress as it reduced the loss of body weight and behavioral alterations. Moreover, kynurenic acid which remained increased in 1-MT treated repeatedly stressed mice was identified to reduce the TNFα inducibility of splenocytes in vitro and in vivo. Thus, psychological stress stimulates cytokine-driven IDO1 activation and Trp depletion which seems to have a central role for developing stress-induced immunosuppression and behavioral alteration. Since patients showed Trp catabolism already prior to surgery, IDO is also a possible target enzyme for humans modulating immune homeostasis and mood