917 research outputs found

    Investigation of foamed metals for application on space capsules annual report, 29 jun. 1963 - 15 aug. 1964

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    Foamed metal development for space capsules - brazing, variable density beam, thermal testing, mechanical tests, and machinin

    Assessment of Service Life for Regenerative ECLSS Resin Beds

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    The International Space Station (ISS) Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) manage and process water at various levels of cleanliness for multiple purposes. The effluent of theWPA and the influent of the OGA require water at very high levels of purity. The bulk of the water purification that occurs in both systems is performed by consumable activated carbon and ion exchange resin beds. Replacement beds must be available on orbit in order to continue the ISS critical processes of water purification and oxygen generation. Various hurdles exist in order to ensure viable spare resin beds. These include the characteristics of resin beds such as: storage environment, shelf life requirements, microbial growth, and variations in the levels and species of contaminants the beds are required to remove. Careful consideration has been given to match water models, bed capacities and spares traffic models to ensure that spares are always viable. The results of these studies and considerations, in particular, how shelf life requirements affect resin bed life management, are documented in this paper

    Assessment of digital image correlation measurement errors: methodology and results

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    Optical full-field measurement methods such as Digital Image Correlation (DIC) are increasingly used in the field of experimental mechanics, but they still suffer from a lack of information about their metrological performances. To assess the performance of DIC techniques and give some practical rules for users, a collaborative work has been carried out by the Workgroup “Metrology” of the French CNRS research network 2519 “MCIMS (Mesures de Champs et Identification en Mécanique des Solides / Full-field measurement and identification in solid mechanics, http://www.ifma.fr/lami/gdr2519)”. A methodology is proposed to assess the metrological performances of the image processing algorithms that constitute their main component, the knowledge of which being required for a global assessment of the whole measurement system. The study is based on displacement error assessment from synthetic speckle images. Series of synthetic reference and deformed images with random patterns have been generated, assuming a sinusoidal displacement field with various frequencies and amplitudes. Displacements are evaluated by several DIC packages based on various formulations and used in the French community. Evaluated displacements are compared with the exact imposed values and errors are statistically analyzed. Results show general trends rather independent of the implementations but strongly correlated with the assumptions of the underlying algorithms. Various error regimes are identified, for which the dependence of the uncertainty with the parameters of the algorithms, such as subset size, gray level interpolation or shape functions, is discussed

    Promoting Recovery from Substance Misuse through Engagement with Community Assets: Asset Based Community Engagement

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    © The Author(s) 2019. Evidence shows that engagement with community resources can aid the process of recovery from substance misuse, yet systematic approaches to mapping resources and building bridges to these for recovery populations are limited. If done successfully, engagement with resources that are pro-social and afford access to meaningful activities not only provides a platform for personal development, but also has the ability to trigger a social contagion of positive behaviour and improve connectedness within communities. The current paper uses Asset Based Community Development (ABCD) as the basis for an enhanced version called Asset Based Community Engagement (ABCE). The work of ABCD has been pivotal in encouraging citizen-led, strengths-based approaches to community development, yet scientific support for it remains limited. While this approach has gained much traction, it has been subject to criticism for being too optimistic and unsystematic. In response to this, the new framework, ABCE, offers a more structured approach to mapping community resources. It does however advance previous work by acknowledging the need to identify current levels of community engagement and barriers to engagement, in order to support empowerment, maximise personal capital and address barriers to engagement. Identifying barriers to engagement should not draw ABCE away from its strengths-based focus but instead, provide a platform for person-centred, holistic support to be provided to those in recovery. To support the new framework, a workbook has been developed, offering a practical output that is intended to be used by the individual in recovery alongside a member of staff within a professional service supporting the individual

    A tale of two towns: A comparative study exploring the possibilities and pitfalls of social capital among people seeking recovery from substance misuse

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    Background: Social capital has become an influential concept in debating and understanding the modern world. Within the drug and alcohol sector, the concept of ‘recovery capital’ has gained traction with researchers suggesting that people who have access to such capital are better placed to overcome their substance use-related problems than those who do not (Cloud and Granfield, 2008), leading to requests for interventions that focus on building social capital networks (Neale & Stevenson, 2015). While accepting that the concept of social capital has enormous potential for addressing the problems associated with drug use, this paper also considers its ‘dark side’. Methods: Data were drawn from semi-structured interviews with 180 participants including 135 people who use drugs and 45 people who formerly used drugs. Results: High levels of trust, acquired through the establishment of dense social networks, are required to initiate recovery. However, these ‘strong bonds’ may also lead to the emergence of what is perceived by others as an exclusive social network that limits membership to those who qualify and abide by the ‘rules’ of the recovery community, particularly around continuous abstinence. Conclusions: Depending on the nature of the networks and the types of links participants have into them being socially connected can both inhibit and encourage recovery. Therefore, the successful application of social capital within the drugs and alcohol field requires a consideration of not only the presence or absence of social connections but their nature, the value they produce, and the social contexts within which they are developed

    Exploring the Potential Role of Family History of Hypertension on Racial Differences in Sympathetic Vascular Transduction

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    The prevalence of hypertension in Non-Hispanic Black (BL) men surpasses all other racial groups. Our laboratory has previously demonstrated exaggerated vasoconstrictor and blood pressure (BP) responses to spontaneous bursts of muscle sympathetic nerve activity (MSNA; sympathetic vascular transduction) in young, healthy BL men compared to their Non-Hispanic White (WH) counterparts. Because a family history of hypertension (FHH) further compounds cardiovascular risk, we wanted to begin to explore the potential impact of a positive (+) FHH on sympathetic vascular transduction. Whether a +FHH influences sympathetic vascular transduction in WH and/or BL men remains unknown. PURPOSE: To begin to explore if +FHH influences sympathetic vascular transduction within and between racial groups. METHODS: 22 men, nine with a +FHH (4 BL men) and 13 without a FHH (-FHH; 6 BL men) were recruited. Beat-to-beat BP (Finometer), femoral artery blood flow (Doppler ultrasound), and MSNA were measured during a 20-minute quiet rest. The mean BP and leg vascular conductance (LVC; blood flow/mean BP) responses to spontaneous bursts of MSNA were quantified via a signal averaging technique. RESULTS: Resting heart rate, BP, and MSNA were not significantly different between groups (all p\u3e0.05). As previously demonstrated by our laboratory, the BL men exhibited an augmented sympathetic vascular transduction compared to the WH men (e.g., peak BP response, WH men: Δ4.1±0.3, BL men: Δ5.6±0.7 mmHg, p=0.04). When accounting for FHH within the groups, the peak BP (WH +FHH: Δ4.4±0.6 vs. WH -FHH: Δ3.8±0.4 mmHg, p=0.4) and nadir LVC responses (WH +FHH: Δ-0.5±0.07 vs. WH -FHH: Δ-0.5±0.09 ml·min-¹·mmHg-¹, p=0.7) were not significantly different between WH men +FHH and WH men –FHH. Likewise, the BL men +FHH exhibited similar peak BP (BL +FHH: Δ6.2±0.7 vs. BL -FHH: Δ5.3±1.1 mmHg, p=0.5) and nadir LVC (BL +FHH: Δ-1.1±0.44 vs. BL -FHH: Δ-0.6±0.10 ml·min-¹·mmHg-¹, p=0.2) responses to bursts of MSNA compared to the BL men –FHH. CONCLUSION: These preliminary findings do not support a role for +FHH in augmented sympathetic vascular transduction, therefore suggesting that racial differences in sympathetic vascular transduction are independent of FHH

    The position of graptolites within Lower Palaeozoic planktic ecosystems.

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    An integrated approach has been used to assess the palaeoecology of graptolites both as a discrete group and also as a part of the biota present within Ordovician and Silurian planktic realms. Study of the functional morphology of graptolites and comparisons with recent ecological analogues demonstrates that graptolites most probably filled a variety of niches as primary consumers, with modes of life related to the colony morphotype. Graptolite coloniality was extremely ordered, lacking any close morphological analogues in Recent faunas. To obtain maximum functional efficiency, graptolites would have needed varying degrees of coordinated automobility. A change in lifestyle related to ontogenetic changes was prevalent within many graptolite groups. Differing lifestyle was reflected by differing reproductive strategies, with synrhabdosomes most likely being a method for rapid asexual reproduction. Direct evidence in the form of graptolithophage 'coprolitic' bodies, as well as indirect evidence in the form of probable defensive adaptations, indicate that graptolites comprised a food item for a variety of predators. Graptolites were also hosts to a variety of parasitic organisms and provided an important nutrient source for scavenging organisms

    Adaptively evolved Escherichia coli for improved ability of formate utilization as a carbon source in sugar???free conditions

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    Background: Formate converted from CO2 reduction has great potential as a sustainable feedstock for biological production of biofuels and biochemicals. Nevertheless, utilization of formate for growth and chemical production by microbial species is limited due to its toxicity or the lack of a metabolic pathway. Here, we constructed a formate assimilation pathway in Escherichia coli and applied adaptive laboratory evolution to improve formate utilization as a carbon source in sugar-free conditions. Results: The genes related to the tetrahydrofolate and serine cycles from Methylobacterium extorquens AM1 were overexpressed for formate assimilation, which was proved by the 13C-labeling experiments. The amino acids detected by GC/MS showed significant carbon labeling due to biomass production from formate. Then, 150 serial subcultures were performed to screen for evolved strains with improved ability to utilize formate. The genomes of evolved mutants were sequenced and the mutations were associated with formate dehydrogenation, folate metabolism, and biofilm formation. Last, 90 mg/L of ethanol production from formate was achieved using fed-batch cultivation without addition of sugars. Conclusion: This work demonstrates the effectiveness of the introduction of a formate assimilation pathway, combined with adaptive laboratory evolution, to achieve the utilization of formate as a carbon source. This study suggests that the constructed E. coli could serve as a strain to exploit formate and captured CO2

    Genome-wide DNA methylation map of human neutrophils reveals widespread inter-individual epigenetic variation

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    The extent of variation in DNA methylation patterns in healthy individuals is not yet well documented. Identification of inter-individual epigenetic variation is important for understanding phenotypic variation and disease susceptibility. Using neutrophils from a cohort of healthy individuals, we generated base-resolution DNA methylation maps to document inter-individual epigenetic variation. We identified 12851 autosomal inter-individual variably methylated fragments (iVMFs). Gene promoters were the least variable, whereas gene body and upstream regions showed higher variation in DNA methylation. The iVMFs were relatively enriched in repetitive elements compared to non-iVMFs, and were associated with genome regulation and chromatin function elements. Further, variably methylated genes were disproportionately associated with regulation of transcription, responsive function and signal transduction pathways. Transcriptome analysis indicates that iVMF methylation at differentially expressed exons has a positive correlation and local effect on the inclusion of that exon in the mRNA transcript
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