559 research outputs found

    Injector for liquid fueled rocket engine

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    An injector for liquid fueled rocket engines wherein a generally flat core having a frustoconical dome attached to one side of the core to serve as a manifold for a first liquid, with the core having a generally circular configuration having an axis. The other side of the core has a plurality of concentric annular first slots and a plurality of annular concentric second slots alternating with the first slots, the second slots having a greater depth than said first slots. A bore extends through the core for inletting a second liquid into said core, the bore intersecting the second slots to feed the second liquid into the second slots. The core also has a plurality of first passageways leading from the manifold to the first annular slots for feeding the first liquid into said first slots. A faceplate brazed to said other side of the core is provided with apertures extending from the first and second slots through said face plate, these apertures being positioned to direct fuel and liquid oxygen into contact with each other in the combustion chamber. The first liquid may be liquid oxygen and the second liquid may be kerosene or liquid hydrogen

    Biofluorescence in Arctic snailfishes

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    12 pages : illustrations (chiefly color) ; 26 cm.Biofluorescence has recently been reported to be phylogenetically widespread and phenotypically variable across bony fishes, and is most common in tropical coral reef lineages. Here we provide the first documentation of prominent biofluorescence in Arctic fishes including two juvenile specimens of Liparis gibbus (variegated snailfish) collected from the coastal waters of Eastern Greenland, as well as an adult L. tunicatus (kelp snailfish) collected in the Bering Strait off of Little Diomede Island, AK. Observations of L. gibbus were made during nighttime dives within kelp forests in iceberg habitats in Southeastern Greenland in August 2019. The juvenile L. gibbus specimens exhibit both green (523-530 nm) and red (674-678 nm) biofluorescence on discrete anatomical areas, which provides a rare example of multiple fluorescent colors emitted from a single individual. Notably, the adult L. tunicatus emitted only red fluorescence in a bilaterally symmetrical pattern of discrete red dots and blotches. Potential weak green biofluorescence was also noted in a flatfish (Hippoglossoides platessoides) collected in Greenland, but in no other Arctic species. As the distribution and function of biofluorescence in marine fishes is further examined, this report adds context to its widespread geographical and environmental distributions, and shows that, although rare, biofluorescence does occur in Arctic fish lineages

    Extended Warm Gas in the ULIRG Mrk273: Galactic Outflows and Tidal Debris

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    We present new HST ACS medium- and narrow-band images and long-slit, optical (4000 - 7200A) spectra obtained using the Isaac Newton Telescope (INT) on La Palma, of the merging system Mrk273. The HST observations sample the [OIII]4959,5007 emission from the galaxy and the nearby continuum. The images show that the morphologies of the extended continuum and the ionised gas emission from the galaxy are decoupled, extending almost perpendicular to each other. In particular, we detect for the first time a spectacular structure of ionised gas in the form of filaments extending ~23 kpc to the east of the nuclear region. The quiescent ionised gas kinematics at these locations suggests that these filaments are tidal debris left over from a secondary merger event that are illuminated by an AGN in the nuclear regions. The images also reveal a complex morphology in the nuclear region of the galaxy for both the continuum and the [OIII] emission. Kinematic disturbance, in the form of broad (FWHM > 500 km s-1) and/or strongly shifted (abs(\DeltaV) >150 km s-1) emission line components, is found at almost all locations within a radius of ~4 kpc to the east and west of the northern nucleus. We fit the profiles of all the emission lines of different ionisation with a kinematic model using up to 3 Gaussian components. From these fits we derive diagnostic line ratios that are used to investigate the ionisation mechanisms at the different locations in the galaxy. We show that, in general, the line ratios are consistent with photoionization by an AGN as the main ionisation mechanism. Finally, the highest surface brightness [OIII] emission is found in a compact region that is coincident with the so-called SE nuclear component. The compactness, kinematics and emission line ratios of this component suggest that it is a separate nucleus with its own AGN.Comment: Accepted for Publication in A&

    Accessing Healthy Food: A sentinel mapping study of healthy food retailing in Scotland

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    This study on the availability of an affordable healthy food shopping basket was commissioned by the Food Standards Agency Scotland and undertaken between 2005 and 2007 by the Centre for the Study of Retailing in Scotland

    The Effects of Astaxanthin on Cognitive Function and Neurodegeneration in Humans: A Critical Review

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    Oxidative stress is a key contributing factor in neurodegeneration, cognitive ageing, cognitive decline, and diminished cognitive longevity. Issues stemming from oxidative stress both in relation to cognition and other areas, such as inflammation, skin health, eye health, and general recovery, have been shown to benefit greatly from antioxidant use. Astaxanthin is a potent antioxidant, which has been outlined to be beneficial for cognitive function both in vitro and in vivo. Given the aforementioned promising effects, research into astaxanthin with a focus on cognitive function has recently been extended to human tissue and human populations. The present critical review explores the effects of astaxanthin on cognitive function and neurodegeneration within human populations and samples with the aim of deciphering the merit and credibility of the research findings and subsequently their potential as a basis for therapeutic use. Implications, limitations, and areas for future research development are also discussed. Key findings include the positive impacts of astaxanthin in relation to improving cognitive function, facilitating neuroprotection, and slowing neurodegeneration within given contexts

    HST/ACS Emission Line Imaging of Low Redshift 3CR Radio Galaxies I: The Data

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    We present 19 nearby (z<0.3) 3CR radio galaxies imaged at low- and high-excitation as part of a Cycle 15 Hubble Space Telescope snapshot survey with the Advanced Camera for Surveys. These images consist of exposures of the H-alpha (6563 \AA, plus [NII] contamination) and [OIII] 5007 \AA emission lines using narrow-band linear ramp filters adjusted according to the redshift of the target. To facilitate continuum subtraction, a single-pointing 60 s line-free exposure was taken with a medium-band filter appropriate for the target's redshift. We discuss the steps taken to reduce these images independently of the automated recalibration pipeline so as to use more recent ACS flat-field data as well as to better reject cosmic rays. We describe the method used to produce continuum-free (pure line-emission) images, and present these images along with qualitative descriptions of the narrow-line region morphologies we observe. We present H-alpha+[NII] and [OIII] line fluxes from aperture photometry, finding the values to fall expectedly on the redshift-luminosity trend from a past HST/WFPC2 emission line study of a larger, generally higher redshift subset of the 3CR. We also find expected trends between emission line luminosity and total radio power, as well as a positive correlation between the size of the emission line region and redshift. We discuss the associated interpretation of these results, and conclude with a summary of future work enabled by this dataset.Comment: 18 pages, 12 figures, accepted for publication in ApJ

    Quantifying full phenological event distributions reveals simultaneous advances, temporal stability and delays in spring and autumn migration timing in long-distance migratory birds

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    Acknowledgements We thank all Fair Isle Bird Observatory staff and volunteers for help with data collection and acknowledge the foresight of George Waterston and Ken Williamson in instigating the observatory and census methodology. We thank all current and previous directors of Fair Isle Bird Observatory Trust for their contributions, particularly Dave Okill and Mike Wood for their stalwart support for the long-term data collection and for the current analyses. Dawn Balmer and Ian Newton provided helpful guidance on manuscript drafts. We thank Ally Phillimore and two anonymous referees for helpful comments. This study would have been impossible without the Fair Isle community's invaluable support and patience over many decades, which is very gratefully acknowledged. WTSM and JMR designed and undertook analyses, wrote the paper and contributed to data collection and compilation, MB contributed to analysis and editing, all other authors oversaw and undertook data collection and compilation and contributed to editing.Peer reviewedPostprin

    Information acquisition differences between experienced and novice time trial cyclists

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    Purpose: To use eye-tracking technology to directly compare information acquisition behavior of experienced and novice cyclists during a self-paced 10 mile (16.1 km) time-trial. Method: Two groups of novice (N=10) and experienced cyclists (N=10) performed a 10-mile self-paced time-trial (TT) on two separate occasions during which a number of feedback variables (speed, distance, power output, cadence, heart rate, and time) were projected within their view. A large RPE scale was also presented next to the projected information and participants. Participants were fitted with a head-mounted eye32 tracker and heart rate monitor. Results: Experienced cyclists performed both time-trials quicker than novices (F1,18=6.8, P=.018) during which they primarily looked at speed (9 of 10 participants) whereas novices primarily looked at distance (6 of 10 participants). Experienced cyclists looked at primary information for longer than novices across the whole time-trial (24.5±4.2% vs. 34.2±6.1%, t18=4.2, P<0.001) and less frequently than novices during the last quarter of the time-trial (49±19 vs. 80±32, t18=-2.6, P=0.009). The most common combination of primary and secondary information looked at by experienced cyclists was speed and distance respectively. Looking at ten different primary-secondary feedback permutations, the novices were less consistent than the experienced cyclists in their information acquisition behavior. Conclusion: This study challenges the importance placed on knowledge of the endpoint to pacing in previous models, especially for experienced cyclists for whom distance feedback was looked at secondary to, but in conjunction with, information about speed. Novice cyclists have a greater dependence upon distance feedback, which they look at for shorter and more frequent periods of time than the experienced cyclists. Experienced cyclists are more selective and consistent in attention to feedback during time-trial cycling

    Orion Crew Exploration Vehicle Launch Abort System Guidance and Control Analysis Overview

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    Aborts during the critical ascent flight phase require the design and operation of Orion Crew Exploration Vehicle (CEV) systems to escape from the Crew Launch Vehicle (CLV) and return the crew safely to the Earth. To accomplish this requirement of continuous abort coverage, CEV ascent abort modes are being designed and analyzed to accommodate the velocity, altitude, atmospheric, and vehicle configuration changes that occur during ascent. Aborts from the launch pad to early in the flight of the CLV second stage are performed using the Launch Abort System (LAS). During this type of abort, the LAS Abort Motor is used to pull the Crew Module (CM) safely away from the CLV and Service Module (SM). LAS abort guidance and control studies and design trades are being conducted so that more informed decisions can be made regarding the vehicle abort requirements, design, and operation. This paper presents an overview of the Orion CEV, an overview of the LAS ascent abort mode, and a summary of key LAS abort analysis methods and results

    Post-feeding activity of Lucilia sericata (Diptera: Calliphoridae) on common domestic indoor surfaces and its effect on development.

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    Developmental data of forensically important blowflies used by entomologists to estimate minimum post mortem interval (mPMI) are established under controlled laboratory conditions for various temperature ranges throughout the stages of egg, 1st-3rd instar, puparia, and adult fly emergence. However, environmental conditions may influence the patterns of development and behaviour of blowflies, potentially impacting on these established development rates. Previous studies investigating indoor colonisation have focused on the delay to oviposition, with behaviour during the post-feeding phase in this setting often overlooked. The environment in which third instar larvae disperse when searching for a pupariation site may vary drastically at both outdoor and indoor scenarios, influencing the activity and distance travelled during this phase and possibly affecting developmental rates. This study investigated the effect of eight common domestic indoor surfaces on dispersal time, distance travelled, and behaviour of post-feeding Lucilia sericata as well as any resulting variation in development. It was found that pupariation and puparia length within a pupariation medium of sawdust (often used in laboratory settings) produced comparable results with that of carpeted environments (those deemed to be 'enclosed'). Non-carpeted environments (those which were 'exposed') produced a delay to pupariation likely due to increased activity and energy expenditure in searching for pupariation sites which enabled burial. In addition, the observed speed of travel during dispersal was seen via time lapse photography to be greater within 'exposed' conditions. Larvae which dispersed upon burnt laminate flooring were observed to travel faster than in all other conditions and showed the only significant variation (P=0.04) in the day of emergence in comparison to the control condition of sawdust. This study has demonstrated that wandering phase activity is affected by the environmental surface which has potential implications for estimating both the distance travelled by dispersing larvae in indoor conditions and with further research, may be a consideration in mPMI calculations.This work was supported by the University of Derby Undergraduate Research Scholarly Scheme (grant number URSS056)
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