5,024 research outputs found

    A Lost Generation: Syrian Refugees and the Right to Education in Turkey

    Get PDF

    Emission Characteristics of an Axially Staged Sector Combustor for a Small Core High OPR Subsonic Aircraft Engine

    Get PDF
    This paper presents the nitrogen oxides, carbon monoxide, and particulate matter emissions of a single sector axially staged combustor sector designed and fabricated by United Technologies Research Center (UTRC) in partnership with NASA under a compact low-emissions combustor contract supported by the NASA Advanced Air Transport Technology (AATT) N+3 project. The test was conducted at NASA Glenn Research Center's CE-5 combustion test facility. The facility provided inlet air temperatures up to 922 K and pressures up to 19.0 bar. The combustor design concept, called Axially Controlled Stoichiometry (ACS), was developed by Pratt & Whitney (P&W) under NASA's Environmentally Responsible Aviation (ERA) program for an N+2 combustor for use in twin-aisle subsonic aircraft engines. Under the N+3 project the ACS combustor was scaled-down for application to small-core N+3 engines for use in single-aisle aircraft. The results show that the NOx and CO emissions characteristics are similar in both the N+2 and N+3 applications. The non-volatile particulate matter (nvPM) emissions trends are similar to CO emissions with an exception at high fuel-air ratio, as inlet air temperature and pressure conditions change from taxi to approach. Three NOx correlation equations are generated to describe theNOx emissions of this combustor. The percentage landing and takeoff (LTO) NOx reduction of the N+3 ACS combustor is between 82% and 89% relative to the ICAO CAEP/6 standard, which meets the NASA N+3 goal of exceeding 80% LTO NOx reduction

    Call Me BIG PAPA: An Extension of Mason’s Information Ethics Framework to Big Data

    Get PDF
    In 1986, Richard Mason proposed the PAPA framework to address four ethical issues society would likely face in the information age: privacy, accuracy, property, and accessibility. In this paper, we propose an extension to the PAPA framework by appending three additional issues relevant to information ethics in the big data era. First, we outline the four components of Mason’s original PAPA. Second, we briefly review the major technological changes that have occurred since Mason proposed his framework. Third, we outline concepts relevant to the big data context. Fourth, we propose and discuss our extension by appending three ethical issues related to behavioral surveillance, interpretation, and governance to Mason’s original PAPA framework, forming BIG PAPA. Lastly, we discuss how these issues impact practice and how they can inform future research

    Design, theory, and measurement of a polarization insensitive absorber for terahertz imaging

    Full text link
    We present the theory, design, and realization of a polarization-insensitive metamaterial absorber for terahertz frequencies. We derive geometrical-independent conditions for effective medium absorbers in general, and for resonant metamaterials specically. Our fabricated design reaches and absorptivity of 78% at 1.145 ThzComment: 6 Pages, 5 figures; figures update

    Tracing the Origin and Spread of Agriculture in Europe

    Get PDF
    The origins of early farming and its spread to Europe have been the subject of major interest for some time. The main controversy today is over the nature of the Neolithic transition in Europe: the extent to which the spread was, for the most part, indigenous and animated by imitation (cultural diffusion) or else was driven by an influx of dispersing populations (demic diffusion). We analyze the spatiotemporal dynamics of the transition using radiocarbon dates from 735 early Neolithic sites in Europe, the Near East, and Anatolia. We compute great-circle and shortest-path distances from each site to 35 possible agricultural centers of origin—ten are based on early sites in the Middle East and 25 are hypothetical locations set at 5° latitude/longitude intervals. We perform a linear fit of distance versus age (and vice versa) for each center. For certain centers, high correlation coefficients (R > 0.8) are obtained. This implies that a steady rate or speed is a good overall approximation for this historical development. The average rate of the Neolithic spread over Europe is 0.6–1.3 km/y (95% confidence interval). This is consistent with the prediction of demic diffusion (0.6–1.1 km/y). An interpolative map of correlation coefficients, obtained by using shortest-path distances, shows that the origins of agriculture were most likely to have occurred in the northern Levantine/Mesopotamian area

    Researching trust in the police and trust in justice: a UK perspective

    Get PDF
    This paper describes the immediate and more distant origins of a programme of comparative research that is examining cross-national variations in public trust in justice and in the police. The programme is built around a module of the fifth European Social Survey, and evolved from a study funded by the European Commission. The paper describes the conceptual framework within which we are operating – developed in large measure from theories of procedural justice. It reviews some of the methodological issues raised by the use of sample surveys to research issues of public trust in the police, public perceptions of institutional legitimacy and compliance with the law. Finally it gives a flavour of some of the early findings emerging from the programme

    The modern use of the extended humeral head (cuff tear arthropathy) hemiarthroplasty.

    Get PDF
    Today, the treatment of osteoarthritis in the rotator cuff-deficient population is largely dominated by reverse shoulder arthroplasty (RSA). Despite the popularity of and increased familiarity with this procedure, the complication rate of RSA remains significant. An extended humeral head hemiarthroplasty may provide a less invasive alternative for select patients with cuff tear arthropathy (CTA) and preserved glenohumeral active elevation. With the indications for reverse arthroplasty expanding to younger patients, there are concerns about the longevity of this implant, as well as the associated revision burden. In the setting of failed RSA, the bone stock available for glenosphere baseplate fixation can be inadequate for reimplantation. The treatment strategies for complex shoulder deformities and failed RSA are limited by patient-specific issues, such as anatomy and risk factors. In this review, we discuss the potential role of extended humeral head hemiarthroplasty (CTA hemiarthroplasty) as a primary surgical option in select patients (1) who have preserved elevation \u3e 90°, (2) who have maintained stability (intact coracoacromial ligament), and (3) who desire to circumvent the complications associated with RSA. Furthermore, CTA hemiarthroplasty may be used for severe glenoid erosion, for a fragmented acromion, and in the revision setting for failed RSA aimed at a reliable salvage procedure
    corecore