577 research outputs found

    Participation of Bell Telephone Laboratories in Project Echo and Experimental Results

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    On August 12, 1960, Echo I, a 100-foot-diameter spherical balloon, was placed in orbit around the earth by the National Aeronautics and Space Administration. The objective was to demonstrate the feasibility of long-distance communication by microwave reflection from a satellite. A two-way coast-to-coast voice circuit was to be established between the Jet Propulsion Laboratory (JPL) facility in California and a station provided by Bell Telephone Laboratories (STL) in New Jersey. Similar tests were also planned with the Naval Research Laboratory and other stations. This paper describes the general organization and operation of the Holmdel, New Jersey, station, and discusses the results of the experiments performed between the balloon launching and March 1, 1961. Successful voice communication was achieved through a variety of modulation methods including frequency modulation with feedback, amplitude modulation, single-sideband modulation, and narrow-band phase modulation. Careful measurements were also made of the loss in the transmission path

    PPARs and Bone Metabolism

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    In this paper we present first analyses and results of a comprehensive measurement campaign investigating the propagation channel in case of direct (base station free) communication between railway vehicles. The measurements cover urban, suburban and rural environments along a multifaceted regional railway network in the south of Bavaria. Beside different operational conditions like front, rear, and flank approaches of trains, we investigated several topological scenarios on both, single and double track sections along the line. We will also discuss the observed characteristic changes in narrow band signal attenuation and Doppler spectra for passages through forests, hilly areas, stations and a tunnel

    Project Echo: System Calculations

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    The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. This paper describes system calculations made in preparation for the experiment and their adaptation to the problem of interpreting the results. The calculations include path loss computations, expected audio signal-to-noise ratios, and received signal strength based on orbital parameters

    A Qualitative Exploration of the Role of Vape Shop Environments in Supporting Smoking Abstinence

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    E-cigarettes are the most popular method of quitting smoking in England and most are purchased in specialist vape shops. This qualitative study explores how the vape shop environment is experienced by quitters to support smoking abstinence. Semi-structured qualitative interviews were conducted to elicit experiences of e-cigarette use, including experiences of vape shops, in 40 people who had used e-cigarettes in a quit attempt. Observations of six shops in a range of locations were also undertaken. Interview and observation data were analysed using inductive thematic analysis and triangulated. At an individual level, smoking abstinence was supported through shop assistants’ attempts to understand customers’ smoking preferences in order to: (i) tailor advice about the most appropriate product; and (ii) offer an ongoing point of contact for practical help. At an interpersonal level, shops offered opportunity to socialise and reinforce a vaping identity, although the environment was perceived as intimidating for some (e.g., new and female users). At a structural level, shops ensured easy access to products perceived to be good value by customers and had adapted to legislative changes. Vape shops can provide effective behavioural support to quitters to maintain smoking abstinence. Health professionals could capitalise on this through partnership working with shops, to ensure best outcomes for clients wanting to use e-cigarettes to quit smoking

    What is the value of peer involvement in advancing tobacco harm reduction?

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    E-cigarettes are considered a disruptive technology [1], evidencing rapid growth in the financial market and attracting a distinct new customer base of would-be quitters, especially in Great Britain and the USA. Where use is permitted, and regulation is favourable to users [2], e-cigarettes have become the most popular method of smoking cessation [3] and for many are a long-term alternative to smoking [4]. Outside of a medical lens, vaping can be recreational, not just a smoking cessation aid [5]. Simply trying vaping has, for many, had the happy side effect of encouraging smoking cessation through a non-medicalised route. Despite the lack of early research endorsement and the absence of health messaging on e-cigarette use, smokers experimented with them anyway, with many making the switch and quitting smoking completely of their own accord. As the evidence supporting their use as a reduced risk product and a substitute for smoking grew, so too have the endorsements, such that the UK now leads the way in a ‘cautiously permissive’ stance towards the use of e-cigarettes [6, 7]

    Functional disruptions of the brain in low back pain: A potential imaging biomarker of functional disability

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    Chronic low back pain (LBP) is one of the leading causes of disability worldwide. While LBP research has largely focused on the spine, many studies have demonstrated a restructuring of human brain architecture accompanying LBP and other chronic pain states. Brain imaging presents a promising source for discovering noninvasive biomarkers that can improve diagnostic and prognostication outcomes for chronic LBP. This study evaluated graph theory measures derived from brain resting-state functional connectivity (rsFC) as prospective noninvasive biomarkers of LBP. We also proposed and tested a hybrid feature selection method (Enet-subset) that combines Elastic Net and an optimal subset selection method. We collected resting-state functional MRI scans from 24 LBP patients and 27 age-matched healthy controls (HC). We then derived graph-theoretical features and trained a support vector machine (SVM) to classify patient group. The degree centrality (DC), clustering coefficient (CC), and betweenness centrality (BC) were found to be significant predictors of patient group. We achieved an average classification accuracy of 83.1%

    Mammographic density and its interaction with other breast cancer risk factors in an Asian population

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    10.1038/sj.bjc.6606085British Journal of Cancer1045871-874BJCA

    Species-Specific Scaling to Define and Conserve the Northern Great Plains Region

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    Prairie ecosystems are in a continuous state of flux, shifting by processes that include variable weather patterns and climatic conditions, disturbance regimes, and more recently, human-induced modification. Similarly, wildlife resources fluctuate across the landscape as a result of these ever-changing conditions; however, human alterations have increased, removed, and manipulated the ecological processes of the prairie. Specifically, the spatial scales at which humans manage and interact with the landscape are often inconsistent or incompatible with the scales required for the persistence of wildlife populations. Our synthesis demonstrates how the spatial scales at which wildlife in the Northern Great Plains of North America operate have been constrained by human intervention. This process of anthropogenic scaling has affected the decline of many native wildlife populations and in some cases has resulted in the complete extirpation of species from the landscape. We use historical observations and recent quantitative data to describe the primary cause of spatial scale alteration for prairie focal species (i.e. plains bison, pronghorn, grassland birds, Greater Sage-grouse, black-tailed prairie dogs, swift fox, prairie rattlesnakes) using migration, home range, distribution, and dispersal distances as metrics. We then describe the role that spatial scale plays in wildlife management of the prairie landscape from the non-profit, state, and federal perspective and how these entities are managing at the scales of each focal species
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