784 research outputs found

    Ablation debris control by means of closed thick film filtered water immersion

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    The performance of laser ablation generated debris control by means of open immersion techniques have been shown to be limited by flow surface ripple effects on the beam and the action of ablation plume pressure loss by splashing of the immersion fluid. To eradicate these issues a closed technique has been developed which ensured a controlled geometry for both the optical interfaces of the flowing liquid film. This had the action of preventing splashing, ensuring repeatable machining conditions and allowed for control of liquid flow velocity. To investigate the performance benefits of this closed immersion technique bisphenol A polycarbonate samples have been machined using filtered water at a number of flow velocities. The results demonstrate the efficacy of the closed immersion technique: a 93% decrease in debris is produced when machining under closed filtered water immersion; the average debris particle size becomes larger, with an equal proportion of small and medium sized debris being produced when laser machining under closed flowing filtered water immersion; large debris is shown to be displaced further by a given flow velocity than smaller debris, showing that the action of flow turbulence in the duct has more impact on smaller debris. Low flow velocities were found to be less effective at controlling the positional trend of deposition of laser ablation generated debris than high flow velocities; but, use of excessive flow velocities resulted in turbulence motivated deposition. This work is of interest to the laser micromachining community and may aide in the manufacture of 2.5D laser etched patterns covering large area wafers and could be applied to a range of wavelengths and laser types

    Project Prometheus: Design and Analysis of a Modular Aerostructure for a Small Launch Vehicle

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    Project Prometheus is a sub-team of the Alabama Rocket Engineering System (ARES) project, which has been in development for about four years. This system is a bi-propellant pressure-fed rocket meant to prove new technology and launch to about 30,000 ft. Project Prometheus is the structural and integration sub-team of Project ARES. The team has worked since August 2020, moving from concept, through preliminary and critical design, and then onto analysis and testing validation and manufacturing. This paper walks through the main requirements, design decisions with rationale, analysis proving the validity of the design, and highlights the important features and the transferability of the concept to other small launch vehicle applications

    Being away or being there: British holidaymakers' motivations and experiences visiting Alanya, Turkey

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    This thesis investigates British holidaymakers' motivations, behaviours and experiences visiting Alanya, Turkey, based on the analysis of quantitative and qualitative data gathered through structured self-administrated questionnaire and semi-structured interviews. Employing a convenience sample of 505 holidaymakers visiting a coastal holiday resort in the Mediterranean, the thesis provides a destination-based analysis of the tourist experience process in three analytical phases. Utilising qualitative and quantitative techniques, the study investigates and addresses, in particular, two specific issues: Motivators, constraints and facilitators of holiday choice; and evaluation of holiday/destination behaviour and experiences. The underlying characteristic of Alanya holiday was found to be seeking 'fun in the sun'. ‗Being away‘ was more important than ‗being there‘ as long as sunny weather and the 'right price‘ were guaranteed. Coastal pleasures dominated the holiday activity, and social and cultural contacts were also significant. Motivations, constraints and facilitators were significant determinants of holiday choice and holiday activity patterns. Supporting consumption experiences were the facilitators of peak experiences. Both peak and supporting consumption experiences were crucial in combination for holidaymakers‘ satisfaction. Preferences and perceptions indicated both similarities and differences between holidaymakers. Differences that are rather more significant were based on repeat visitation patterns. Socio-demographic characteristics were more significant for pre-and on-site experience phases. Trip characteristics were more significant for on-site- and post-experience phases. This study adds substantially to our understanding of tourist motivations, behaviours and experiences and provides additional evidence in terms of their complexity and heterogeneity. Demonstrating the relevance of peak touristic experiences and supporting consumption experiences, the study highlighted the importance of the constraints/facilitators, on the structural, interpersonal and intrapersonal levels. Using mixed methods research design and studying three phases of the tourist experience process simultaneously, the study provides both a theoretical and a methodological base for future research. The study has important implications for the management and marketing of destination experiences. This study calls for cross-national research involving its replication with random sampling in the same resort area, and other tourist resorts in the Mediterranean

    5-HT2B antagonism arrests non-canonical TGF-β1-induced valvular myofibroblast differentiation

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    Transforming growth factor-β1 (TGF-β1) induces myofibroblast activation of quiescent aortic valve interstitial cells (AVICs), a differentiation process implicated in calcific aortic valve disease (CAVD). The ubiquity of TGF-β1 signaling makes it difficult to target in a tissue specific manner; however, the serotonin 2B receptor (5-HT2B) is highly localized to cardiopulmonary tissues and agonism of this receptor displays pro-fibrotic effects in a TGF-β1-dependent manner. Therefore, we hypothesized that antagonism of 5-HT2B opposes TGF-β1-induced pathologic differentiation of AVICs and may offer a druggable target to prevent CAVD. To test this hypothesis, we assessed the interaction of 5-HT2B antagonism with canonical and non-canonical TGF-β1 pathways to inhibit TGF-β1-induced activation of isolated porcine AVICs in vitro. Here we show that AVIC activation and subsequent calcific nodule formation is completely mitigated by 5-HT2B antagonism. Interestingly, 5-HT2B antagonism does not inhibit canonical TGF-β1 signaling as identified by Smad3 phosphorylation and activation of a partial plasminogen activator inhibitor-1 promoter (PAI-1, a transcriptional target of Smad3), but prevents non-canonical p38 MAPK phosphorylation. It was initially suspected that 5-HT2B antagonism prevents Src tyrosine kinase phosphorylation; however, we found that this is not the case and time-lapse microscopy indicates that 5-HT2B antagonism prevents non-canonical TGF-β1 signaling by physically arresting Src tyrosine kinase. This study demonstrates the necessity of non-canonical TGF-β1 signaling in leading to pathologic AVIC differentiation. Moreover, we believe that the results of this study suggest 5-HT2B antagonism as a novel therapeutic approach for CAVD that merits further investigation

    Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist

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    Citation: Frese, D. A., Reinhardt, C. D., Bartle, S. J., Rethorst, D. N., Hutcheson, J. P., Nichols, W. T., . . . Thomson, D. U. (2016). Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist. Journal of Animal Science, 94(2), 581-591. doi:10.2527/jas2015-9824Angus crossbred steers (n = 40; 563 +/- 44 kg) were used to examine the effects of handling method and fat thickness on the blood chemistry and physiology of market steers. Steers were blocked by backfat (BF) thickness and were randomly assigned to treatment groups: low-stress handling (LSH) and aggressive handling (AH). Cattle were then ran-domly assigned to one of 5 blocks containing 4 steers from the LSH and AH treatments. Steers in the LSH treatment were walked and AH cattle were run through a course of 1,540 m. Blood samples were obtained via jugular venipuncture before handling (BASE), at 770 m (LAP1), at 1,540 m (LAP2), and at1 h (1H) and 2 h (2H) after finishing the course. Blood samples were analyzed for plasma lactate (LAC), creatinine kinase (CK), base excess (BE), blood pH (pH), serum cortisol (CORT) concentrations, and venous carbon dioxide (PvCO2) and oxygen (PvO2) pressures. Heart rate (HR), respiratory rate (RR), and rectal temperature (TEMP) were measured at the same intervals. Cattle in the AH treatment had greater (P 0.14). Blood pH in AH cattle was decreased compared with that in LSH cattle (P 0.13) at BASE, 1H, or 2H. Heart rate and TEMP were increased in AH cattle compared to LSH (P > 0.01). Serum cortisol was increased (P < 0.05) in AH compared to that in LSH cattle at LAP1 (87.5 vs. 58.9 nmol/ L), LAP2 (144.4 vs. 93.1 nmol/ L), and 1H (113.5 vs. 53.1 nmol/ L). Although RR was not differ-ent between LSH and AH, PvCO2 was decreased in AH compared to that in LSH (P < 0.05) at LAP2 (30.6 vs. 39.3 mmHg) and PvO2 was increased at LAP1 (42.7 vs. 33.5 mmHg) and at LAP2 (51.5 vs. 36.6 mmHg). Lactate was increased in AH cattle in the thicker BF group at 1H (P < 0.05), and blood pH was decreased at LAP1, LAP2, and 1H (P < 0.05) compared to the thinner BF cohorts. Four AH steers became exhausted (EXH) and did not complete the course. Increased CK, decreased PvCO2, and muscle tremors occurred in EXH steers compared to non-exhausted AH cohorts. Results of this study show that AH causes physiologic and blood chemistry changes in steers, which can be potentially detrimental to cattle, emphasizing the need for lowstress handling practices

    The Energetic Particle Detector (EPD) Investigation and the Energetic Ion Spectrometer (EIS) for the Magnetospheric Multiscale (MMS) Mission

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    Abstract The Energetic Particle Detector (EPD) Investigation is one of 5 fields-and-particles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth’s magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly’s Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from a required low energy limit of 20 keV for protons and 45 keV for oxygen ions, up to \u3e0.5 MeV (with capabilities to measure up to \u3e1 MeV). FEEPS measures instantaneous all sky images of energetic electrons from 25 keV to \u3e0.5 MeV, and also measures total ion energy distributions from 45 keV to \u3e0.5 MeV to be used in conjunction with EIS to measure all sky ion distributions. In this report we describe the EPD investigation and the details of the EIS sensor. Specifically we describe EPD-level science objectives, the science and measurement requirements, and the challenges that the EPD team had in meeting these requirements. Here we also describe the design and operation of the EIS instruments, their calibrated performances, and the EIS in-flight and ground operations. Blake et al. (The Flys Eye Energetic Particle Spectrometer (FEEPS) contribution to the Energetic Particle Detector (EPD) investigation of the Magnetospheric Magnetoscale (MMS) Mission, this issue) describe the design and operation of the FEEPS instruments, their calibrated performances, and the FEEPS in-flight and ground operations. The MMS spacecraft will launch in early 2015, and over its 2-year mission will provide comprehensive measurements of magnetic reconnection at Earth’s magnetopause during the 18 months that comprise orbital phase 1, and magnetic reconnection within Earth’s magnetotail during the about 6 months that comprise orbital phase 2
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