Updating the Lambda modes of a nuclear power reactor

[EN] Starting from a steady state configuration of a nuclear power reactor some situations arise in which the reactor configuration is perturbed. The Lambda modes are eigenfunctions associated with a given configuration of the reactor, which have successfully been used to describe unstable events in BWRs. To compute several eigenvalues and its corresponding eigenfunctions for a nuclear reactor is quite expensive from the computational point of view. Krylov subspace methods are efficient methods to compute the dominant Lambda modes associated with a given configuration of the reactor, but if the Lambda modes have to be computed for different perturbed configurations of the reactor more efficient methods can be used. In this paper, different methods for the updating Lambda modes problem will be proposed and compared by computing the dominant Lambda modes of different configurations associated with a Boron injection transient in a typical BWR reactor. (C) 2010 Elsevier Ltd. All rights reserved.This work has been partially supported by the Spanish Ministerio de Educacion y Ciencia under projects ENE2008-02669 and MTM2007-64477-AR07, the Generalitat Valenciana under project ACOMP/2009/058, and the Universidad Politecnica de Valencia under project PAID-05-09-4285.González Pintor, S.; Ginestar Peiro, D.; Verdú Martín, GJ. (2011). Updating the Lambda modes of a nuclear power reactor. Mathematical and Computer Modelling. 54(7):1796-1801. https://doi.org/10.1016/j.mcm.2010.12.013S1796180154

Hydrostatic intestinal edema induced signaling pathways: potential role of mechanical forces.

BACKGROUND: Hydrostatic intestinal edema initiates a signal transduction cascade that results in smooth muscle contractile dysfunction. Given the rapid and concurrent alterations in the mechanical properties of edematous intestine observed with the development of edema, we hypothesize that mechanical forces may serve as a stimulus for the activation of certain signaling cascades. We sought to examine whether isolated similar magnitude mechanical forces induced the same signal transduction cascades associated with edema. METHODS: The distal intestine from adult male Sprague Dawley rats was stretched longitudinally for 2 h to 123% its original length, which correlates with the interstitial stress found with edema. We compared wet-to-dry ratios, myeloperoxidase activity, nuclear signal transduction and activator of transcription (STAT)-3 and nuclear factor (NF)-kappa B DNA binding, STAT-3 phosphorylation, myosin light chain phosphorylation, baseline and maximally stimulated intestinal contractile strength, and inducible nitric oxide synthase (iNOS) and sodium hydrogen exchanger 1-3 messenger RNA (mRNA) in stretched and adjacent control segments of intestine. RESULTS: Mechanical stretch did not induce intestinal edema or an increase in myeloperoxidase activity. Nuclear STAT-3 DNA binding, STAT-3 phosphorylation, and nuclear NF-kappa B DNA binding were significantly increased in stretched seromuscular samples. Increased expression of sodium hydrogen exchanger 1 was found but not an increase in iNOS expression. Myosin light chain phosphorylation was significantly decreased in stretched intestine as was baseline and maximally stimulated intestinal contractile strength. CONCLUSION: Intestinal stretch, in the absence of edema/inflammatory/ischemic changes, leads to the activation of signaling pathways known to be altered in intestinal edema. Edema may initiate a mechanotransductive cascade that is responsible for the subsequent activation of various signaling cascades known to induce contractile dysfunction

How large should whales be?

The evolution and distribution of species body sizes for terrestrial mammals is well-explained by a macroevolutionary tradeoff between short-term selective advantages and long-term extinction risks from increased species body size, unfolding above the 2g minimum size induced by thermoregulation in air. Here, we consider whether this same tradeoff, formalized as a constrained convection-reaction-diffusion system, can also explain the sizes of fully aquatic mammals, which have not previously been considered. By replacing the terrestrial minimum with a pelagic one, at roughly 7000g, the terrestrial mammal tradeoff model accurately predicts, with no tunable parameters, the observed body masses of all extant cetacean species, including the 175,000,000g Blue Whale. This strong agreement between theory and data suggests that a universal macroevolutionary tradeoff governs body size evolution for all mammals, regardless of their habitat. The dramatic sizes of cetaceans can thus be attributed mainly to the increased convective heat loss is water, which shifts the species size distribution upward and pushes its right tail into ranges inaccessible to terrestrial mammals. Under this macroevolutionary tradeoff, the largest expected species occurs where the rate at which smaller-bodied species move up into large-bodied niches approximately equals the rate at which extinction removes them.Comment: 7 pages, 3 figures, 2 data table

Functional divergence in the role of N-linked glycosylation in smoothened signaling

The G protein-coupled receptor (GPCR) Smoothened (Smo) is the requisite signal transducer of the evolutionarily conserved Hedgehog (Hh) pathway. Although aspects of Smo signaling are conserved from Drosophila to vertebrates, significant differences have evolved. These include changes in its active sub-cellular localization, and the ability of vertebrate Smo to induce distinct G protein-dependent and independent signals in response to ligand. Whereas the canonical Smo signal to Gli transcriptional effectors occurs in a G protein-independent manner, its non-canonical signal employs Gαi. Whether vertebrate Smo can selectively bias its signal between these routes is not yet known. N-linked glycosylation is a post-translational modification that can influence GPCR trafficking, ligand responsiveness and signal output. Smo proteins in Drosophila and vertebrate systems harbor N-linked glycans, but their role in Smo signaling has not been established. Herein, we present a comprehensive analysis of Drosophila and murine Smo glycosylation that supports a functional divergence in the contribution of N-linked glycans to signaling. Of the seven predicted glycan acceptor sites in Drosophila Smo, one is essential. Loss of N-glycosylation at this site disrupted Smo trafficking and attenuated its signaling capability. In stark contrast, we found that all four predicted N-glycosylation sites on murine Smo were dispensable for proper trafficking, agonist binding and canonical signal induction. However, the under-glycosylated protein was compromised in its ability to induce a non-canonical signal through Gαi, providing for the first time evidence that Smo can bias its signal and that a post-translational modification can impact this process. As such, we postulate a profound shift in N-glycan function from affecting Smo ER exit in flies to influencing its signal output in mice

Exploring Patient Experience of Chest Pain Before and After Implementation of an Early Rule-Out Pathway for Myocardial Infarction: A Qualitative Study.

STUDY OBJECTIVE: High-sensitivity cardiac troponin assays enable myocardial infarction to be excluded in the emergency department (ED). As part of a prospective clinical trial, we explore how introducing an early rule-out pathway may affect patient experience of chest pain. METHODS: In a qualitative study, participants presenting to the ED with suspected acute coronary syndrome, and for whom the diagnosis of myocardial infarction was excluded, were interviewed before (n=23) or after (n=26) implementation of an early rule-out pathway. Preimplementation, diagnosis of myocardial infarction was excluded on serial troponin testing requiring admission to the hospital. Postimplementation, diagnosis could be excluded in the ED, enabling direct patient discharge. Semistructured interviews exploring the patients' illness experience were conducted approximately 1 week postdischarge, transcribed verbatim, and analyzed thematically. Themes emerging pre- and postimplementation are described. RESULTS: Common themes emerged across both pathways: participants commonly sought health care advice before presenting to the ED; a discordance may exist between the objective interpretation of troponin results by clinicians and the patients' experience of illness; and pretest information, trust in the clinician, and active listening may enhance reassurance gained from negative test results. Other themes related to the care pathway were that routine care procedures appeared to be a source of frustration for participants requiring hospital admission, and patients assessed with the early rule-out pathway appeared less likely to appraise their future health status. CONCLUSION: The early rule-out of myocardial infarction may be enhanced by recognition of patient out-of-hospital experience and improved communication surrounding reassurance and future cardiovascular health goals

Translating shared decision-making into health care clinical practices: Proof of concepts

Background: There is considerable interest today in shared decision-making (SDM), defined as a decision-making process jointly shared by patients and their health care provider. However, the data show that SDM has not been broadly adopted yet. Consequently, the main goal of this proposal is to bring together the resources and the expertise needed to develop an interdisciplinary and international research team on the implementation of SDM in clinical practice using a theory-based dyadic perspective. Methods: Participants include researchers from Canada, US, UK, and Netherlands, representing medicine, nursing, psychology, community health and epidemiology. In order to develop a collaborative research network that takes advantage of the expertise of the team members, the following research activities are planned: 1) establish networking and on-going communication through internet-based forum, conference calls, and a bi-weekly e-bulletin; 2) hold a two-day workshop with two key experts (one in theoretical underpinnings of behavioral change, and a second in dyadic data analysis), and invite all investigators to present their views on the challenges related to the implementation of SDM in clinical practices; 3) conduct a secondary analyses of existing dyadic datasets to ensure that discussion among team members is grounded in empirical data; 4) build capacity with involvement of graduate students in the workshop and online forum; and 5) elaborate a position paper and an international multi-site study protocol. Discussion: This study protocol aims to inform researchers, educators, and clinicians interested in improving their understanding of effective strategies to implement shared decision-making in clinical practice using a theory-based dyadic perspective

Presenting Symptoms in Men and Women Diagnosed With Myocardial Infarction Using Sex‐Specific Criteria

Background: Sex‐specific criteria are recommended for the diagnosis of myocardial infarction, but the impact of these on presenting characteristics is unknown. Methods and Results: We evaluated patient‐reported symptoms in 1941 patients (39% women) with suspected acute coronary syndrome attending the emergency department in a substudy of a prospective trial. Standardized criteria defined typical and atypical presentations based on pain nature, location, radiation, and additional symptoms. Diagnosis of myocardial infarction was adjudicated using a high‐sensitivity cardiac troponin I assay with sex‐specific thresholds (>16 ng/L women, >34 ng/L men). Patients identified who were missed by the contemporary assay with a uniform threshold (≥50 ng/L) were reclassified by this approach. Type 1 myocardial infarction was diagnosed in 16% (184/1185) of men and 12% (90/756) of women, with 9 (5%) men and 27 (30%) women reclassified using high‐sensitivity cardiac troponin I and sex‐specific thresholds. Chest pain was the presenting symptom in 91% (1081/1185) of men and 92% (698/756) of women. Typical symptoms were more common in women than in men with myocardial infarction (77% [69/90] versus 59% [109/184]; P=0.007), and differences were similar in those reclassified (74% [20/27] versus 44% [4/9]; P=0.22). The presence of ≥3 typical features was associated with a positive likelihood ratio for the diagnosis of myocardial infarction in women (positive likelihood ratio, 1.18; 95% CI, 1.03–1.31) but not in men (positive likelihood ratio 1.09; 95% CI, 0.96–1.24). Conclusions: Typical symptoms are more common and have greater predictive value in women than in men with myocardial infarction whether or not they are diagnosed using sex‐specific criteria

The Role of Creativity in Entrepreneurship

This paper evaluates the contribution of creativity to entrepreneurship theory and practice in terms of building an holistic and transdisciplinary understanding of its impact. Acknowledgement is made of the subjectivist theory of entrepreneurship which embraces randomness, uncertainty and ambiguity but these factors should then be embedded in wider business and social contexts. The analysis is synthesised into a number of themes, from consideration of its definition, its link with personality and cognitive style, creativity as a process and the use of biography in uncovering data on creative entrepreneurial behaviour. Other relevant areas of discussion include creativity’s link with motivation, actualisation and innovation, as well as the interrogation of entrepreneurial artists as owner/managers. These factors are embedded in a critical evaluation of how creativity contributes to successful entrepreneurship practice. Modelling, measuring and testing entrepreneurial creativity are also considered and the paper includes detailed consideration of several models of creativity in entrepreneurship. Recommendations for future theory and practice are also made

Phase 1/2a Study of the Malaria Vaccine Candidate Apical Membrane Antigen-1 (AMA-1) Administered in Adjuvant System AS01B or AS02A

Contains fulltext : 79496.pdf (publisher's version ) (Open Access)BACKGROUND: This Phase 1/2a study evaluated the safety, immunogenicity, and efficacy of an experimental malaria vaccine comprised of the recombinant Plasmodium falciparum protein apical membrane antigen-1 (AMA-1) representing the 3D7 allele formulated with either the AS01B or AS02A Adjuvant Systems. METHODOLOGY/PRINCIPAL FINDINGS: After a preliminary safety evaluation of low dose AMA-1/AS01B (10 microg/0.5 mL) in 5 adults, 30 malaria-naive adults were randomly allocated to receive full dose (50 microg/0.5 mL) of AMA-1/AS01B (n = 15) or AMA-1/AS02A (n = 15), followed by a malaria challenge. All vaccinations were administered intramuscularly on a 0-, 1-, 2-month schedule. All volunteers experienced transient injection site erythema, swelling and pain. Two weeks post-third vaccination, anti-AMA-1 Geometric Mean Antibody Concentrations (GMCs) with 95% Confidence Intervals (CIs) were high: low dose AMA-1/AS01B 196 microg/mL (103-371 microg/mL), full dose AMA-1/AS01B 279 microg/mL (210-369 microg/mL) and full dose AMA-1/AS02A 216 microg/mL (169-276 microg/mL) with no significant difference among the 3 groups. The three vaccine formulations elicited equivalent functional antibody responses, as measured by growth inhibition assay (GIA), against homologous but not against heterologous (FVO) parasites as well as demonstrable interferon-gamma (IFN-gamma) responses. To assess efficacy, volunteers were challenged with P. falciparum-infected mosquitoes, and all became parasitemic, with no significant difference in the prepatent period by either light microscopy or quantitative polymerase chain reaction (qPCR). However, a small but significant reduction of parasitemia in the AMA-1/AS02A group was seen with a statistical model employing qPCR measurements. SIGNIFICANCE: All three vaccine formulations were found to be safe and highly immunogenic. These immune responses did not translate into significant vaccine efficacy in malaria-naive adults employing a primary sporozoite challenge model, but encouragingly, estimation of parasite growth rates from qPCR data may suggest a partial biological effect of the vaccine. Further evaluation of the immunogenicity and efficacy of the AMA-1/AS02A formulation is ongoing in a malaria-experienced pediatric population in Mali. TRIAL REGISTRATION: www.clinicaltrials.gov NCT00385047