86 resultados para Stress-based forming limit


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Background: Despite its prevalence and prognostic impact, primary cachexia is not well understood. Its potential to cause considerable psychological stress indicates the need for qualitative research to help understand the perspectives of those affected.

Objective: The aims of this study were to describe the perspectives of patients with primary cachexia, of their relatives, and of the healthcare professionals involved in their care and to demonstrate how this evidence can be applied in practice at 4 different levels of application ranging from empathy to coaching.

Methods: A review of the qualitative literature and empirical qualitative investigation was used to understand the experiences of patients and relatives and the perspectives of professionals.

Results: The main worries expressed by patients and relatives concerned appetite loss, changing appearance, prognosis, and social interaction. We also describe their coping responses and their views of professionals’ responses. The main concerns of professionals related to poor communication, lack of clinical guidance, and lack of professional education.

Conclusions: Understanding patients’, families’, and professionals’ perspectives, and mapping that understanding onto what we know about the trajectory and prognosis of the condition, provides the evidence base for good practice. Qualitative research has a central role to play in providing the knowledge base for the nursing care of patients with cachexia.

Implications for Practice: The evidence provided can improve nurses’ insight and assist them in assessment of status, the provision of guidance, and coaching. There is a need for the development of a holistic, information-based integrated care pathway for those with cancer cachexia and their families.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The preparation and characterisation are described of a robust, reversible, hydrogen peroxide optical sensor, based on the fluorescent quenching of the dye ion-pair [Ru(bpy)(3)(2+)(Ph4B-)(2)], by O-2 produced by the catalytic breakdown of H2O2, utilizing the inorganic catalyst RuO2 center dot xH(2)O. The main feature of this system is the one-pot formulation of a coating ink that, when dried, forms an active single-layer fluorescence-based H2O2 sensor, demonstrably capable of detecting H2O2 over the range of 0.01 to 1 M, with a relative standard deviation of ca. 4% and a calculated lower limit of detection of 0.1 mM. These sensors are sterilisable, using dry-heat, and stable when stored over 40 days, without exhibiting any loss in sensitivity or response characteristics.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We discuss the quantum-circuit realization of the state of a nucleon in the scope of simple simmetry groups. Explicit algorithms are presented for the preparation of the state of a neutron or a proton as resulting from the composition of their quark constituents. We estimate the computational resources required for such a simulation and design a photonic network for its implementation. Moreover, we highlight that current work on three-body interactions in lattices of interacting qubits, combined with the measurement-based paradigm for quantum information processing, may also be suitable for the implementation of these nucleonic spin states.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Traditional static analysis fails to auto-parallelize programs with a complex control and data flow. Furthermore, thread-level parallelism in such programs is often restricted to pipeline parallelism, which can be hard to discover by a programmer. In this paper we propose a tool that, based on profiling information, helps the programmer to discover parallelism. The programmer hand-picks the code transformations from among the proposed candidates which are then applied by automatic code transformation techniques.

This paper contributes to the literature by presenting a profiling tool for discovering thread-level parallelism. We track dependencies at the whole-data structure level rather than at the element level or byte level in order to limit the profiling overhead. We perform a thorough analysis of the needs and costs of this technique. Furthermore, we present and validate the belief that programs with complex control and data flow contain significant amounts of exploitable coarse-grain pipeline parallelism in the program’s outer loops. This observation validates our approach to whole-data structure dependencies. As state-of-the-art compilers focus on loops iterating over data structure members, this observation also explains why our approach finds coarse-grain pipeline parallelism in cases that have remained out of reach for state-of-the-art compilers. In cases where traditional compilation techniques do find parallelism, our approach allows to discover higher degrees of parallelism, allowing a 40% speedup over traditional compilation techniques. Moreover, we demonstrate real speedups on multiple hardware platforms.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Considerable evidence has accumulated on the association between pregnancy-specific stress and adverse birth outcomes with an increasing number of measures of pregnancy-specific stress being developed internationally. However, the introduction of these measures has not always been theoretically or psychometrically grounded, resulting in questions about the quality and direction of such research. This review summarizes evidence on the reliability and validity of pregnancy-specific stress measures identified between 1980 and October 2010. Fifteen pregnancy-specific stress measures were identified. Cronbach’s alpha coefficient ranged from 0.51–0.96 and predictive validity data on preterm birth were reported for five measures. Convergent validity data suggest that pregnancy-specific stress is related to, but distinct from, global stress. Findings from this review consolidate current knowledge on pregnancy-specific stress as a consistent predictor of premature birth. This review also advances awareness of the range of measures of pregnancy-specific stress and documents their strengths and limitations based on published reliability and validity data. Careful consideration needs to be given as to which measures to use in future research to maximize the development of stress theory in pregnancy and appropriate interventions for women who experience stress in pregnancy. An international, strategic collaboration is recommended to advance knowledge in this area of study.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, thus conferring resistance to oxidative stress. Using high-resolution mass spectrometry, we recently reclassified one such peroxiredoxin, bacterioferritin comigratory protein (BCP) of Escherichia coli, as an atypical 2-Cys peroxiredoxin that functions through the formation of an intramolecular disulfide bond between the active and resolving cysteine. An engineered E. coli BCP, which lacked the resolving cysteine, retained enzyme activity through a novel catalytic pathway. Unlike the active cysteine, the resolving cysteine of BCP peroxiredoxins is not conserved across all members of the family. To clarify the catalytic mechanism of native BCP enzymes that lack the resolving cysteine, we have investigated the BCP homologue of Burkholderia cenocepacia. We demonstrate that the B. cenocepacia BCP (BcBCP) homologue functions through a 1-Cys catalytic pathway. During catalysis, BcBCP can utilize thioredoxin as a reductant for the sulfenic acid intermediate. However, significantly higher peroxidase activity is observed utilizing glutathione as a resolving cysteine and glutaredoxin as a redox partner. Introduction of a resolving cysteine into BcBCP changes the activity from a 1-Cys pathway to an atypical 2-Cys pathway, analogous to the E. coli enzyme. In contrast to the native B. cenocepacia enzyme, thioredoxin is the preferred redox partner for this atypical 2-Cys variant. BCP-deficient B. cenocepacia exhibit a growth-phase-dependent hypersensitivity to oxidative killing. On the basis of sequence alignments, we believe that BcBCP described herein is representative of the major class of bacterial BCP peroxiredoxins. To our knowledge, this is the first detailed characterization of their catalytic activity. These studies support the subdivision of the BCP family of peroxiredoxins into two classes based on their catalytic activity.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The prevalence of multicore processors is bound to drive most kinds of software development towards parallel programming. To limit the difficulty and overhead of parallel software design and maintenance, it is crucial that parallel programming models allow an easy-to-understand, concise and dense representation of parallelism. Parallel programming models such as Cilk++ and Intel TBBs attempt to offer a better, higher-level abstraction for parallel programming than threads and locking synchronization. It is not straightforward, however, to express all patterns of parallelism in these models. Pipelines are an important parallel construct, although difficult to express in Cilk and TBBs in a straightfor- ward way, not without a verbose restructuring of the code. In this paper we demonstrate that pipeline parallelism can be easily and concisely expressed in a Cilk-like language, which we extend with input, output and input/output dependency types on procedure arguments, enforced at runtime by the scheduler. We evaluate our implementation on real applications and show that our Cilk-like scheduler, extended to track and enforce these dependencies has performance comparable to Cilk++.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Oxidative stress appears to be important in the pathogenesis of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Single-nucleotide polymorphisms (SNPs) of antioxidant enzyme genes may play a part in determining individual susceptibility to these diseases. The Factors Influencing the Barrett's Adenocarcinoma Relationship (FINBAR) study is a population-based, case-control study of BE and EAC in Ireland. DNA from EAC (n = 207), BE (> or =3 cm BE at endoscopy with specialized intestinal metaplasia on biopsy, n = 189) and normal population controls (n = 223) were analyzed. Several SNPs spanning the genes for glutathione S-transferase P1 (GSTP1), manganese superoxide dismutase (MnSOD) and glutathione peroxidase 2 (GPX2) were genotyped using multiplex polymerase chain reaction and SNaPshottrade mark. The chi(2) test was used to compare genotype and allele frequencies between case and control subjects. Linkage disequilibrium between SNPs was quantified using Lewontin's D' value and haplotype frequency estimates obtained using Haploview. Eleven SNPs were genotyped (six for GSTP1, three for MnSOD and two for GPX2); all were in Hardy-Weinberg equilibrium. None was significantly associated with EAC or BE even before Bonferroni correction. Odds ratios for EAC for individual SNPs ranged from 0.68 [95% confidence interval (CI) 0.43-1.08] to 1.25 (95% CI 0.73-2.16), and for BE from 0.84 (95% CI 0.52-1.30) to 1.30 (95% CI 0.85-1.97). SNPs in all three genes were in strong linkage disequilibrium (D' > 0.887) but haplotype analysis did not show any significant association with EAC or BE. SNPs involving the GSTP1, MnSOD and GPX2 genes were not associated with BE or EAC. Further studies aimed at identifying susceptibility genes should focus on different antioxidant genes or different pathways.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

An immunoaffinity chromatographic (IAC) method for the selective extraction and concentration of 13 organophosphorus pesticides (OPs, including coumaphos, parathion, phoxim, quinalphos, dichlofenthion, triazophos, azinphos-ethyl, phosalone, isochlorthion, parathion-methyl, cyanophos, disulfoton, and phorate) prior to analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The IAC column was prepared by covalently immobilizing a monoclonal antibody with broad specificity for OPs on CNBr-activated Sephrose 4B. The column capacity ranged from 884 to 2641 ng/mL of gel. The optimum elution solvent was 0.01 M phosphate-buffered saline containing 80% methanol. The breakthrough volume of the IAC column was found to be 400 mL. Recoveries of OPs from spiked environmental samples by IAC cleanup and HPLC-MS/MS analysis ranged from 60.2 to 107.1%, with a relative standard deviation below 11.1%. The limit of quantitation for 13 OPs ranged from 0.01 to 0.13 ng/mL (ng/g). The application of IAC cleanup coupled to HPLC-MS/MS in real environmental samples demonstrated the potential of this method for the determination of OP residues in environmental samples at trace levels.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

ABSTRACT BACKGROUND: Acute exposure to high-altitude stimulates free radical formation in lowlanders yet whether this persists during chronic exposure in healthy well-adapted and maladapted highlanders suffering from chronic mountain sickness (CMS) remains to be established. METHODS: Oxidative-nitrosative stress [ascorbate radical (A•-), electron paramagnetic resonance spectroscopy and nitrite (NO2-), ozone-based chemiluminescence] was assessed in venous blood of 25 male highlanders living at 3,600 m with (n = 13, CMS+) and without (n = 12, CMS-) CMS. Twelve age and activity-matched healthy male lowlanders were examined at sea-level and during acute hypoxia. We also measured flow-mediated dilatation (FMD), arterial stiffness (AIx-75) and carotid intima-media thickness (IMT). RESULTS: Compared to normoxic lowlanders, oxidative-nitrosative stress was moderately increased in CMS- (P < 0.05) as indicated by elevated A•- (3,191 ± 457 vs. 2,640 ± 445 arbitrary units (AU)] and lower NO2- (206 ± 55 vs. 420 ± 128 nmol/L) whereas vascular function remained preserved. This was comparable to that observed during acute hypoxia in lowlanders in whom vascular dysfunction is typically observed. In contrast, this response was markedly exaggerated in CMS+ (A•-: 3,765 ± 429 AU and NO2- : 148 ± 50 nmol/L) compared to both CMS- and lowlanders (P < 0.05). This was associated with systemic vascular dysfunction as indicated by lower (P < 0.05 vs. CMS-) FMD (4.2 ± 0.7 vs. 7.6 ± 1.7 %) and increased AIx-75 (23 ± 8 vs. 12 ± 7 %) and carotid IMT (714 ± 127 vs. 588 ± 94 µM). CONCLUSIONS: Healthy highlanders display a moderate sustained elevation in oxidative-nitrosative stress that unlike the equivalent increase evoked by acute hypoxia in healthy lowlanders, failed to affect vascular function. Its more marked elevation in patients with CMS may contribute to systemic vascular dysfunction.Clinical Trials Gov Registration # NCT011827921Neurovascular Research Laboratory, Faculty of Health, Science and Sport, University of Glamorgan, Wales, UK;2Sondes Moléculaires en Biologie et Stress Oxydant, Institut de Chimie Radicalaire, CNRS UMR 7273, Aix-Marseille University, France;3Department of Cardiology, University Hospital of Bern, Bern, Switzerland;4Institute of Clinical Physiology, CNR, Pisa, Italy;5Instituto Bolivano de Biologia de Altura, La Paz, Bolivia;6Centre for Clinical and Population Sciences, Queen's University Belfast, Belfast, Northern Ireland,7Botnar Center for Clinical Research, Hirslanden Group, Lausanne, Switzerland;8Facultad de Ciencias, Departamento de Biología, Universidad de Tarapacá, Arica, Chile and9Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland*Drs Bailey, Rimoldi, Scherrer and Sartori contributed equally to this workCorrespondence: Damian Miles Bailey, Neurovascular Research Laboratory, Faculty of Health, Science and Sport, University of Glamorgan, UK CF37 4AT email: dbailey1@glam.ac.uk.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Spanish gluten-free rice, cereals with gluten, and pureed baby foods were analysed for total (t-As) and inorganic As (i-As) using ICP-MS and HPLC-ICP-MS, respectively. Besides, pure infant rice from China, USA, UK and Spain were also analysed. The i-As contents were significantly higher in gluten-free rice than in cereals mixtures with gluten, placing infants with celiac disease at high risk. All rice-based products displayed a high i-As content, with values being above 60% of the t-As content and the remainder being dimethylarsinic acid (DMA). Approximately 77% of the pure infant rice samples showed contents below 150 µg kg(-1) (Chinese limit). When daily intake of i-As by infants (4-12 months) was estimated and expressed on a bodyweight basis (µg d(-1) kg(-1)), it was higher in all infants aged 8-12 months than drinking water maximum exposures predicted for adults (assuming 1 L consumption per day for a 10 µg L(-1) standard).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Ecotoxicological screening of dust sampled throughout a Kenyan tannery was conducted using a luminescence (lux)-based bacterial biosensor for both solid and liquid assays. This was complemented by chemical analysis in an attempt to identify possible causative toxic components. The biosensor results showed a highly significant (p <0.001) difference in both solid and liquid phase toxicity in samples collected from various identified sampling points in the tannery. A positive correlation was observed between results of the solid and liquid phase techniques, for most of the sampling points indicating that the toxic contaminants were bioavailable both in the solid and liquid state. However, the results generally indicated toxicity associated with liquid phase except certain areas in solid phase such as chemical handling, buffing area and weighing. The most toxic tannery area identified was the weighing area (p <0.001), showing the lowest bioluminescence for both the solid (0.38 +/- 2.21) and liquid phases (0.01 +/- 0.001). Chromium was the metal present in the highest concentration indicating levels higher than the stipulated regulatory requirement of 0.5 mg Cr/m3 for total Cr (highest Cr concentration was at chemical handling at 209.24 mg l(-1)) in all dust samples. The weighing area had the highest Ni concentration (1.87 mg l(-1)) and the chemical handling area showed the highest Zn concentration (31.9 mg l(-1)). These results raise environmental health concerns, as occupational exposure to dust samples from this site has been shown to give rise to elevated concentrations (above the stipulated levels) of chromium in blood, urine and some body tissues, with inhalation being the main route. Health and Safety Executive (HSE), UK, and American Conference of Governmental Industrial Hygienist (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), USA stipulates an occupational exposure limit of 0.5 mg Cr/m3 (8 h TWA) for total chromium. However, schedule 1 of Controls of substances hazardous to health (COSHH) regulations developed by HSE, indicate 0.05 mg m3 (8 h TWA reference periods) to be the limit for Cr (VI) exposure. The exposure limit for individual (e.g., Cr, Zn, Ni etc.) contaminants (homogeneity) was not exceeded, but potential impact of heterogeneity (multi-element synergistic effect) on toxicity requires application of the precautionary principle.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The flow of carbon from plant roots into soil supports a range of microbial processes and is therefore critical to ecosystem function and health. Pollution-induced stress, which influences rhizosphere C flow is of considerable potential importance, and therefore needs to be evaluated. This paper reports on a method, based on reporter gene technology, for quantifying pollutant effects on rhizosphere C flow. The method uses the lux-marked rhizobacterium Pseudomonas fluorescens, where bioluminescence output of this biosensor is directly correlated with the metabolic activity and reports on C flow in root exudate. Plantago lanceolata was treated with paraquat (representing a model pollutant stress) in a simple microcosm system. The lux-biosensor response correlated closely with C concentrations in the exudate and demonstrated that the pollutant stress increased the C flow from the plantago roots, 24 h after application of the herbicide. The lux-reporter system therefore potentially offers a technique for use in assessing the impact of pollutant stress on rhizosphere C flow through the soil microbial biomass.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In this paper, a new approach for extracting stress intensity factors (SIFs) by the extended element-free Galerkin method, through a crack closure integral (CCI) scheme, is proposed. The CCI calculation is used in conjunction with a local smoothing technique to improve the accuracy of the computed SIFs in a number of case studies of linear elastic fracture mechanics. The cases involve problems of mixed-mode, curved crack and thermo-mechanical loading. The SIFs by CCI, displacement and stress methods are compared with those based on the M-integral technique reported in the literature. The proposed CCI method involves very simple relations, and still gives good accuracy. The convergence of the results is also examined.