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The high-strength 7xxx series aluminium alloys can fulfil the need for light, high strength materials necessary to reduce carbon-emissions, and are extensively used in aerospace for weight reduction purposes. However, as all major high-strength materials, these alloys can be sensitive to stress-corrosion cracking (SCC) through anodic dissolution and hydrogen embrittlement (HE). Here, we study at the near-atomic-scale the intra- and inter-granular microstructure ahead and in the wake of a propagating SCC crack. Moving away from model alloys and non-industry standard tests, we perform a double cantilever beam (DCB) crack growth test on an engineering 7xxx Al-alloy. H is found segregated to planar arrays of dislocations and to grain boundaries that we can associate to the combined effects of hydrogen-enhanced localised plasticity (HELP) and hydrogen-enhanced decohesion (HEDE) mechanisms. We report on a Mg-rich amorphous hydroxide on the corroded crack surface and evidence of Mg-related diffusional processes leading to dissolution of the strengthening η-phase precipitates ahead of the crack. High-strength Al alloys are sensitive to stress corrosion cracking and hydrogen embrittlement that limit their applications. Here the authors examine them at near-atomic scale using advanced microscopy and reveal hydrogen at dislocations and grain boundaries, and subsequent microstructural changes. [ABSTRACT FROM AUTHOR]

Simultaneous protocols typically yield poorer stimulus equivalence outcomes than do other protocols commonly used in equivalence research. Two independent groups of three 3-member equivalence sets of stimuli were used in conditional discrimination procedures in two conditions, one using the standard simultaneous protocol and the other using a hybrid simultaneous training and simple-to-complex testing. Participants completed the two conditions in one long session in Experiment 1, but in separate sessions in Experiment 2. The same stimulus sets used in Experiment 1 were randomized for the two conditions in Experiment 2. Overall, accuracy was better with the hybrid than with the standard protocol in both experiments. The equivalence yield was also better under the hybrid than under the standard protocol in each experiment. The results suggest that the order of testing for emergent relations may account for the difficulty often encountered with the standard simultaneous protocol. [ABSTRACT FROM AUTHOR]

The concept map tool set forth by Novak and colleagues is underutilized in education. A meta-analysis has encouraged teachers to make extensive use of concept mapping, and researchers have advocated computer-based concept mapping applications that exploit hyperlink technology. Through an NSF sponsored geosciences education grant, middle and secondary science teachers participated in professional development to apply computer-based concept mapping in project-based learning (PBL) units that investigated local watersheds. Participants attended a summer institute, engaged in a summer through spring online learning academy, and presented PBL units at a subsequent fall science teachers' convention. The majority of 17 teachers who attended the summer institute had previously used the concept mapping strategy with students and rated it highly. Of the 12 teachers who continued beyond summer, applications of concept mapping ranged from collaborative planning of PBL projects to building students' vocabulary to students producing maps related to the PBL driving question. Barriers to the adoption and use of concept mapping included technology access at the schools, lack of time for teachers to advance their technology skills, lack of student motivation to choose to learn, and student difficulty with linking terms. In addition to mitigating the aforementioned barriers, projects targeting teachers' use of technology tools may enhance adoption by recruiting teachers as partners from schools as well as a small number that already are proficient in the targeted technology and emphasizing the utility of the concept map as a planning tool. [ABSTRACT FROM AUTHOR]

Background: The absence of a pharmacokinetic interaction between the proton pump inhibitor esomeprazole (40 mg) and acetylsalicylic acid (aspirin, ASA; 325 mg) has previously been established. Objective: This study set out to investigate the potential for pharmacodynamic interaction between low-dose ASA and esomeprazole in healthy volunteers, by measuring ASA antiplatelet activity. Study Design: This was a single-center, open-label, two-period, randomized crossover study. Participants: Healthy male and female volunteers aged 18-75 years were included. All volunteers received ASA 81 mg once daily for 5 days prior to the study (pre-screen). Subjects were eligible for inclusion if they had aspirin reactivity units (ARU, as measured by the VerifyNow ASA assay) of <550 on Day 6. Intervention: After pre-screening and a washout period of at least 14 days, eligible volunteers received ASA 81 mg with or without esomeprazole 20 mg once daily for 5 days in randomized order, with a 14-day washout between treatments. Main Outcome Measure: The main outcome measure was the antiplatelet activity of ASA, as assessed by ARU ratio relative to baseline in the VerifyNow ASA assay; suppression of serum thromboxane B2 (TXB2) was a secondary endpoint. Statistical comparisons were made using linear mixed models. Results: A total of 29 volunteers (19 aged ≥50 years; 8 women; 21 men) were evaluable for pharmacodynamic analysis (per protocol). All volunteers on both treatments achieved ARU<550 at Day 6. The geometric mean ratio of D ay 6 to D ay 1 (baseline) platelet aggregation was 0.70 (95 % confidence interval [CI] 0.68, 0 .72) with ASA alone and 0.71 (95% CI 0.69, 0. 74) with ASA + esomeprazole. The ratio of platelet aggregation (ASA + esomeprazole /ASA) was 1.02 (95 % CI 0.99, 1.05). ASA administered alone or with esomeprazole reduced serum TXB2 by more than 99.5%. The ratio of suppression of serum TXB2 levels (ASA + esomeprazole / ASA) was 1.06 (95% CI 0.88, 1.29). The combination of ASA and esomeprazole was well tolerated. Conclusion: No pharmacodynamic interaction between low-dose ASA and esomeprazole was found with regard to platelet function. Trial Registration: Registered at ClinicalTrials. gov as NCT01199328. [ABSTRACT FROM AUTHOR]

Intermittent swim stress (ISS) produces deficits in swim escape learning and increases immobility in the forced swim test (FST). A previous attempt to reverse this immobility with the selective serotonin reuptake inhibitor (SSRI), fluoxetine (FLX), was unsuccessful, but the sensitivity of this immobility to other types of antidepressants is unknown. In experiment 1, we evaluate the ability of the norepinephrine (NE) selective reuptake inhibitor (NSRI), desipramine (DES), to reverse the ISS-induced immobility in the FST compared to confined controls (CC), while in experiment 2, we test the efficacy of either the SSRI or NSRI to reverse the immobility produced by either ISS or continuous swim (CS)/FST. Rats were exposed to their respective behavioral pretreatment (ISS, CS/FST, or CC) and were then injected with an antidepressant or saline solution 23.5, 5, and 1 h prior to the FST. In experiment 1, DES reduced immobility and increased the climbing behavior in the ISS group without altering these behaviors in the CC, while in experiment 2, the CS/FST-induced immobility was reduced by both antidepressants (i.e., FLX and DES), while the ISS-induced immobility was only affected by DES. These results suggest that the ISS-induced immobility is mediated through the NE system and may represent a model for atypical depression. [ABSTRACT FROM AUTHOR]

Ailanthus altissima is an invasive, dioecious deciduous tree common at the interface between urban and rural areas in the mid-Atlantic region, U.S.A. To examine spatial patterns of abundance and associations with land use type, we mapped all mature female trees in nine 89.5 ha plots (805.5 ha total area) across a typical urban-to-rural land use gradient using aerial images obtained via remote sensing supplemented by detailed ground referencing. Rural plots were dominated by forest and had the lowest density of mature females (0.007 females ha-1); urban and suburban plots did not differ significantly in mean density (0.37 females ha-1 vs. 0.34 females ha-1, respectively). Individuals in urban plots were more evenly distributed, but were not associated with a wider variety of land uses and were closer to roads or openings than those in suburban plots. Given less available habitat per unit area in urban than in suburban environments, these patterns suggest that Ailanthus fits the profile of an invasive species that may be proliferating outward from urban centers. With continued disturbances associated with development in the suburban areas, and timber harvesting in the rural areas, further spread of Ailanthus seems likely. [ABSTRACT FROM AUTHOR]

In this paper we investigate the use of a shadow-based delineation program for identifying segments in imagery of a closed canopy, deciduous forest, in West Virginia, USA, as a way to reduce the noise associated with per-pixel classification in forested environments. Shadows typically cluster along the boundaries of trees and therefore can be used to provide a network of nodes for the delineation of segments. A minimum cost path algorithm, where cost is defined as the cumulative sum of brightness values traversed along the connecting route, was used to connect shadow clumps. To test this approach, a series of classifications was undertaken using a multispectral digital aerial image of a six hectare test site and a minimum cost path segmentation. Three species were mapped: oaks, red maple and yellow poplar. The accuracy of an aspatial maximum likelihood classification (termed PERPIXEL classification) was 68.5%, compared to 74.0% for classification using the mean vector of the segments identified with the minimum cost path algorithm (MEAN_SEG), and 78% when the most common class present in the segment is assigned to the entire segment (POSTCLASS_SEG). By comparison, multispectral classification of the multispectral data using the field-mapped polygons of individual trees as segments, produced an accuracy of 82.3% when the mean vector of the polygon was used for classification (MEAN_TREE), and 85.7% when the most common class was assigned to the entire polygon (POSTCLASS_TREE). A moving window-based post-classification majority filter (POSTCLASS_MAJ5BY5) produced an intermediate accuracy value, 73.8%. The minimum cost path segmentation algorithm was found to correctly delineate approximately 28% of the trees. The remaining trees were either segmented, aggregated, or a combination of both segmented and aggregated. Varying the threshold that was used to discriminate shadows appeared to have little effect on the number of correctly delineated trees, or on the overall accuracy of the multispectral classification, although it did have a notable effect on the proportions of aggregated and segmented trees. [ABSTRACT FROM AUTHOR]

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the formation of prostanoids by the enzyme cyclooxygenase (COX). Work in the past 15 years has shown that COX exists in two forms: COX1, which is largely associated with physiological functions, and COX2, which is largely associated with pathological functions. Heated debate followed the introduction of selective COX2 inhibitors around 5 years ago: do these drugs offer any advantages over the traditional NSAIDs they were meant to replace, particularly in regard to gastrointestinal and cardiovascular side effects? Here we discuss the evidence and the latest recommendations for the use of selective inhibitors of COX2 as well as the traditional NSAIDs. [ABSTRACT FROM AUTHOR]

Central injection of angiotensin II (ANGII) induces pressor and regional haemodynamic effects. Here we have investigated the systemic and regional cardiovascular changes induced by injection of ANGII into the superficial layer of the superior colliculus (SC) of male rats anaesthetised with urethane. In addition, we have used the AT1 receptor-selective antagonist, losartan, and the AT2 receptor-selective antagonist, PD123319 to characterise the receptor(s) mediating these effects. Injection of ANGII (0.1, 1 and 10 nmol/rat) into the superficial layer of the SC significantly ( P < 0.05) increased, in a dose-dependent manner, the mean arterial blood pressure (MAP) while decreasing the heart rate, (e.g. by 37 ± 4 beats min–1, at 1 nmol, P < 0.05). The increases in blood pressure induced by ANGII (1 nmol; 43 ± 6 mmHg, n = 5) were greatly reduced (> 85%) by pre-administration to the SC of PD123319 (50 nmol/rat), but were unaffected by losartan (50 nmol/rat). Similarly, PD123319 prevented the decrease in heart rate induced by ANGII while losartan did not affect it. Injection of ANGII (1 nmol) also increased ( P < 0.01) total peripheral resistance (TPR; control, 2.36 ± 0.1 mmHg ml–1 min 100 g body weight) by 130 ± 10% ( n = 5) and reduced the cardiac output (CO; control, 99.8 ± 1.3 ml min–1) by 51 ± 3% ( n = 5), as determined by radioactive microspheres. The increase in TPR was associated with increases in the vascular resistances of organs, such as the left and right kidney (390 ± 15%, P < 0.01 and 352 ± 12%, P < 0.01 respectively), the skeletal muscle (91 ± 7%, P < 0.05, n = 5), the stomach (43 ± 2%, P < 0.01, n = 5), the colon (50 ± 3%, P < 0.05, n = 5) and the caecum (65 ± 5%, P < 0.05, n = 5). Pre-treatment of the SC with PD123319 reduced ( P < 0.01) the increases in TPR and vascular resistance, and the reduction in CO caused by ANGII. Losartan did not affect the responses to ANGII. Thus, injection of ANGII into the SC causes complex haemodynamic changes which are sensitive to AT2 receptor antagonism. AT2 receptors are, therefore, the predominant mediators of the actions of ANGII into the superior colliculus of the rat. [ABSTRACT FROM AUTHOR]

Highlights advances in researches concerning endothelins. Effect on blood pressure of mammals; Role in the development of the embryo; Involvement in pathologies such as myocardial ischemia and renal failure; Production of non-peptide antagonists.

Comments on the question of what the endothelin peptides do and how they do it, as discussed at the Third International Conference on Endothelin, held February 15-17, 1993. Investigation of endothelin action is entering a new phase with characterization of the receptors concerned and the advent of selective, potent and orally active receptor antagonists. Selective ETA receptor; Non-selective ETB receptor; Details.