1,059 research outputs found
High density Schottky barrier IRCCD sensors for SWIR applications at intermediate temperature
Monolithic 32 x 64 and 64 x 1:128 palladium silicide (Pd2Si) interline transfer infrared charge coupled devices (IRCCDs) sensitive in the 1 to 3.5 micron spectral band were developed. This silicon imager exhibits a low response nonuniformity of typically 0.2 to 1.6% rms, and was operated in the temperature range between 40 to 140 K. Spectral response measurements of test Pd2Si p-type Si devices yield quantum efficiencies of 7.9% at 1.25 microns, 5.6% at 1.65 microns 2.2% at 2.22 microns. Improvement in quantum efficiency is expected by optimizing the different structural parameters of the Pd2Si detectors. The spectral response of the Pd2Si detectors fit a modified Fowler emission model. The measured photo-electric barrier height for the Pd2Si detectors is 0.34 eV and the measured quantum efficiency coefficient, C1, is 19%/eV. The dark current level of Pd2Si Schottky barrier focal plane arrays (FPAs) is sufficiently low to enable operation at intermediate temperatures at TV frame rates. Typical dark current level measured at 120 K on the FPA is 2 nA/sq cm. The operating temperature of the Pd2Si FPA is compatible with passive cooler performance. In addition, high density Pd2Si Schottky barrier FPAs are manufactured with high yield and therefore represent an economical approach to short wavelength IR imaging. A Pd2Si Schottky barrier image sensor for push-broom multispectral imaging in the 1.25, 1.65, and 2.22 micron bands is being studied. The sensor will have two line arrays (dual band capability) of 512 detectors each, with 30 micron center-to-center detector spacing. The device will be suitable for chip-to-chip abutment, thus providing the capability to produce large, multiple chip focal planes with contiguous, in-line sensors
Charge-coupled-device parallel-to-serial converter
A CCD parallel-to-serial converter comprising two successions of charge transfer stages, recurrently side-loaded with respective ones of parallelly supplied charge packets, then serially unloaded by time-interleaved respective shift register operations. The charge packets converted to time-division-multiplexed serial form are supplied to a shared electrometer, and the electrometer response is de-multiplexed. Preferably, shift register operations are carried forward concurrently at the same rate, but with the final charge transfer stages clocked in phases staggered in time
Radiometric infrared focal plane array imaging system for thermographic applications
This document describes research performed under the Radiometric Infrared Focal Plane Array Imaging System for Thermographic Applications contract. This research investigated the feasibility of using platinum silicide (PtSi) Schottky-barrier infrared focal plane arrays (IR FPAs) for NASA Langley's specific radiometric thermal imaging requirements. The initial goal of this design was to develop a high spatial resolution radiometer with an NETD of 1 percent of the temperature reading over the range of 0 to 250 C. The proposed camera design developed during this study and described in this report provides: (1) high spatial resolution (full-TV resolution); (2) high thermal dynamic range (0 to 250 C); (3) the ability to image rapid, large thermal transients utilizing electronic exposure control (commandable dynamic range of 2,500,000:1 with exposure control latency of 33 ms); (4) high uniformity (0.5 percent nonuniformity after correction); and (5) high thermal resolution (0.1 C at 25 C background and 0.5 C at 250 C background)
Related Party Transactions and Earnings Management
This study examines the association between related party transactions and earnings man-agement, based on a sample of 50 Indonesian publicly listed companies for the periods ending 2004 and 2005. The hypothesis developed in this study draw on past literature and the tenets of agency theory which suggest that the existence of related party transactions represent potential conflict of interest which may results in earnings management and appropriation by controlling shareholder to minority shareholders. The empirical findings of the study suggest that there is no statistically significant evidence of the association between related party transactions and earnings manage-ment attributes. Additional sensitivity analysis conducted with alternative measures of earnings management and related party transactions confirm the initial regression results. The results of this study suggest that the mere presence of related party transactions in Indonesian companies does not necessarily indicate that management engage in greater earnings management. This study pro-vides a valuable starting point for similar research in other developing countries
Multichip imager with improved optical performance near the butt region
A compound imager consists of two or more individual chips, each with at least one line array of sensors thereupon. Each chip has a glass support plate attached to the side from which light reaches the line arrays. The chips are butted together end-to-end to make large line arrays of sensors. Because of imperfections in cutting, the butted surfaces define a gap. Light entering in the region of the gap is either lost or falls on an individual imager other than the one for which it is intended. This results in vignetting and/or crosstalk near the butted region. The gap is filled with an epoxy resin or other similar material which, when hardened, has an index of referaction near that of the glass support plate
A Weak Gravity Conjecture for Scalar Field Theories
We show that the recently proposed weak gravity conjecture\cite{AMNV0601} can
be extended to a class of scalar field theories. Taking gravity into account,
we find an upper bound on the gravity interaction strength, expressed in terms
of scalar coupling parameters. This conjecture is supported by some
two-dimensional models and noncommutative field theories.Comment: version published in JHE
The Chagos Islands cases: the empire strikes back
Good governance requires the accommodation of multiple interests in the cause of decision making. However, undue regard for particular sectional interests can take their toll upon public faith in government administration. Historically, broad conceptions of the good of the commonwealth were employed to outweigh the interests of groups that resisted colonisation. In the decision making of the British Empire, the standard approach for justifying the marginalisation of the interests of colonised groups was that they were uncivilised and that particular hardships were the price to be paid for bringing to them the imperial dividend of industrial society. It is widely assumed that with the dismantling of the British Empire, such impulses and their accompanying jurisprudence became a thing of the past. Even as decolonisation proceeded apace after the Second World War, however, the United Kingdom maintained control of strategically important islands with a view towards sustaining its global role. In an infamous example from this twilight period of empire, in the 1960s imperial interests were used to justify the expulsion of the Chagos islanders from the British Indian Ocean Territory (BIOT). Into the twenty-first century, this forced elision of the UK’s interests with the imperial “common good” continues to take centre stage in courtroom battles over the islanders’ rights, being cited before domestic and international tribunals in order to maintain the Chagossians’ exclusion from their homeland. This article considers the new jurisprudence of imperialism which has emerged in a string of decisions which have continued to marginalise the Chagossians’ interests
Neocortex expansion is linked to size variations in gene families with chemotaxis, cell–cell signalling and immune response functions in mammals
Increased brain size is thought to have played an important role in the evolution of mammals and is a highly variable trait across lineages. Variations in brain size are closely linked to corresponding variations in the size of the neocortex, a distinct mammalian evolutionary innovation. The genomic features that explain and/or accompany variations in the relative size of the neocortex remain unknown. By comparing the genomes of 28 mammalian species, we show that neocortical expansion relative to the rest of the brain is associated with variations in gene family size (GFS) of gene families that are significantly enriched in biological functions associated with chemotaxis, cell–cell signalling and immune response. Importantly, we find that previously reported GFS variations associated with increased brain size are largely accounted for by the stronger link between neocortex expansion and variations in the size of gene families. Moreover, genes within these families are more prominently expressed in the human neocortex during early compared with adult development. These results suggest that changes in GFS underlie morphological adaptations during brain evolution in mammalian lineage
Understanding Lifeguard Recruitment and Selection Practices in Victorian Aquatic and Recreation Centers (ARCs)
Extensive research has focused on human resource management (HRM) and recruitment and selection practices across different settings. However, there is a gap in the scholarly literature in ARC settings, including lifeguards. Additionally, the aquatics industry is experiencing unprecedented levels of lifeguard turnover within aquatic facilities. The recruitment and selection process can impact employee turnover. Therefore, an important first step to address lifeguard turnover is to better understand the current recruitment and selection practices of lifeguards. This study focuses on the recruitment and selection practices of ARC management to better understand the recruitment and selection of lifeguards. The analysis is based on 16 semi-structured interviews with ARC managers involved in lifeguard recruitment and selection. Participants included center managers, assistant center managers, and operations managers/coordinators. A deductive analysis was able to effectively explain the current recruitment and selection practices for recruiting lifeguards in Victorian ARCs
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Survey of women's experiences of care in a new freestanding midwifery unit in an inner city area of London, England - 1: Methods and women׳s overall ratings of care
Objective: To describe and compare women’s choices and experiences of maternity care before and after the opening of the Barkantine Birth Centre, a new freestanding midwifery unit in an inner city area.
Design: Telephone surveys undertaken in late pregnancy and about six weeks after birth in two separate time periods, Phase 1 before the birth centre opened and Phase 2 after it had opened.
Setting: Tower Hamlets, a deprived inner city borough in east London, England, 2007-2010.
Participants: 620 women who were resident in Tower Hamlets and who satisfied the Barts and the London NHS Trust’s eligibility criteria for using the birth centre. Of these, 259 women were recruited to Phase 1 and 361 to Phase 2.
Measurements and findings: Women who satisfied the criteria for birth centre care and who booked antenatally for care at the birth centre were significantly more likely to rate their care as good or very good overall than corresponding women who also satisfied these criteria but booked initially at the hospital. Women who started labour care in spontaneous labour at the birth centre were significantly more likely to be cared for by a midwife they had already met, have one to one care in labour and have the same midwife with them throughout their labour. They were also significantly more likely to report that the staff were kind and understanding, that they were treated with respect and dignity and that their privacy was respected.
Key conclusions and implications for practice: This survey in an inner city area showed that women who chose the freestanding midwifery unit care had positive experiences to report. Taken together with the findings of the Birthplace Programme, It adds further weight to the evidence in support of freestanding midwifery unit care for women without obstetric complications
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