224 research outputs found

    Navigation, Commercial Exchange and the Problem of Long-Distance Control in England and the English East India Company, 1673-1755

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    In this dissertation I address the related problems of expertise and long-distance control in the context of British navigation and the bureaucratic practices of the English East India Company. Expertise, in particular, is used as a framework from which I build outward to establish a stronger understanding of commercial trade, the circulation of knowledge and, most crucially, the place of the metropole. The first half of this dissertation introduces expertise and long-distances control and puts the concepts into historical context through the example of navigation between 1673 and 1755. Navigation is illustrative of the problem of expertise because it was a contentious subject at the time and, therefore, the contemporary debates can be followed. Expertise is a crucial problem because it directly addresses power and who controls knowledge. Thus, the question of navigational expertise ties directly to the problem of long-distance control. Therefore, my dissertation begins by moving outward from navigational instruction at the Royal Mathematical School to the practice of navigation on Edmond Halleys first Paramore voyage. In the context of global commercial exchange, long-distance control became an increasing priority for those who sought to assert such control from a presumed centre onto agents around the globe. As such, the second half of the dissertation continues to follow actors further away from London with the setting moving to India and China where I contrast the idea of long-distance control with the reality. In practice the East India Company had little ability to impose itself on either its own employees or on the peoples with whom the Company wished to trade. Instead, the Companys efforts often drew attention to its ignorance of Asian trade and served to underline its weakness in the first part of the eighteenth century. The dissertation concludes by questioning the notion of the metropole and the periphery in the history of science and suggests an inversion of the traditional locations, with London now a periphery rather than centre, a state of affairs more in line with the situation at the time

    Uniform Computer Information Transactions Act: Bringing Commercial Law into the 21st Century

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    The e-commerce revolution has redefined the way business is transacted everywhere. Meanwhile, the body of commercial law lags behind the fast pace of technological changes and has yet to effectively address the numerous issues presented by radical changes in the world of commerce such as electronic contracts, electronic signatures, shrinkwrap agreements, and click-wrap agreements. In an effort to establish the Commonwealth of Virginia as a national leader on this subject, in 2000 the Virginia General Assembly passed the Uniform Computer Information Transactions Act ( UCITA ). UCITA legislation has been introduced in a handful of other states but the only other state that has passed UCITA is Maryland. By all accounts it is too early to tell whether these laws will meet the needs of the business community in this era of high technology and whether they will be effective if only passed by a limited number of states

    Estimated workload intensity during volunteer aquarium dives

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    Background: This study aimed to characterize the physiological demands of working dives on volunteer divers at a public aquarium in the USA. Aims: To estimate the workloads associated with volunteer dives in a US aquarium. Methods: Participants completed a medical and diving history questionnaire. Measurements included blood pressure before and after diving and continuous ECG (Holter) monitoring during diving. Dive profiles were recorded using loggers. Mean workload was estimated from total air consumption. Results Twenty-seven divers recorded 49 air dives over 5 days. Two-thirds were male and ages ranged from 40 to 78 years. Typically, each diver made two dives with a 30-60 min surface interval. Mean heart rate while diving was 100 beats per minute (bpm). Mean estimated workload during the dives recorded during this study was 5.8 metabolic equivalents (METS), with a range from 4.1 to 10.5. The highest mean recorded heart rate was 120 bpm over 40 min, vacuuming the floor in the shark exhibit. Conclusions: Given the mean age of this sample and the prevalence of cardiovascular risk factors (body mass index, high cholesterol and hypertension), it may be prudent for aquariums to regularly monitor SAC/kg and heart rate in volunteer divers, to identify which tasks require the highest workload intensity. Divers with existing cardiovascular risk factors might then be employed in dives with lighter workloads. In conclusion, volunteer dives at this aquarium required a mean workload intensity that was described by recreational divers as moderate. The highest workload, at 10 METS for 23 min, would be considered by many recreational divers as exhausting

    Interfacial pattern formation far from equilibrium

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    Over the past few years diffusion-controlled systems have been shown to share a common set of interfacial morphologies. The singular nature of the microscopic dynamics of surface tension and kinetic growth far from equilibrium are critical to morphology selection, with special importance attributed to the anisotropy of these effects. The morphologies which develop can be organized via a morphology diagram according to the driving force and the effective anisotropy. We focus on the properties of the dense-branching morphology (DBM) which appears for sufficiently weak effective anisotropy, and the nature of morphology transitions between the DBM and dendritic growth stabilized by either surface tension or kinetic effects. The DBM is studied in the Hele-Shaw cell, and its structure analyzed by linear stability analysis. A comparison is made between the power spectrum of the structure and the stability analysis. We then provide a detailed account of the morphology diagram and morphology transitions in an anisotropic Hele-Shaw cell. Theoretically the question of morphology transitions is addressed within the boundary-layer model by computing selected velocities as a function of the undercooling for different values of the surface tension and the kinetic term. We argue that the fastest growing morphology is selected whether it is the DBM, surface tension dendrites, or kinetic dendrites. A comparison is made with our experimental results in electrochemical deposition for the correspondence between growth velocities and morphology transitions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26972/1/0000539.pd

    Multi-particle three-dimensional coordinate estimation in real-time optical manipulation

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    oai:ojs.pkp.sfu.ca:article/304We have previously shown how stereoscopic images can be obtained in our three-dimensional optical micromanipulation system [J. S. Dam et al, Opt. Express 16, 7244 (2008)]. Here, we present an extension and application of this principle to automatically gather the three-dimensional coordinates for all trapped particles with high tracking range and high reliability without requiring user calibration. Through deconvolving of the red, green, and blue colour planes to correct for bleeding between colour planes, we show that we can extend the system to also utilize green illumination, in addition to the blue and red. Applying the green colour as on-axis illumination yields redundant information for enhanced error correction, which is used to verify the gathered data, resulting in reliable coordinates as well as producing visually attractive images

    The physical constraints on a new LoBAL QSO at z=4.82

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    Very few low-ionization broad absorption line (LoBAL) QSOs have been found at high redshifts to date. One high-redshift LoBAL QSO, J0122+1216, was recently discovered at the Lijiang 2.4-m Telescope with an initial redshift determination of 4.76. Aiming to investigate its physical properties, we carried out follow-up observations in the optical and near-IR spectroscopy. Near-IR spectra from UKIRT and P200 confirms that it is a LoBAL, with a new redshift determination of 4.82±0.014.82\pm0.01 based on the \mgii~ emission-line. The new \mgii~ redshift determination reveals strong blueshifts and asymmetry of the high-ionization emission lines. We estimated a black hole mass of 2.3×109M\sim 2.3\times 10^9 M_\odot and Eddington ratio of 1.0\sim 1.0 according to the empirical \mgii-based single-epoch relation and bolometric correction factor. It is possible that strong outflows are the result of an extreme quasar environment driven by the high Eddington ratio. A lower limit on the outflowing kinetic power (>0.9%LEdd>0.9\% L_{Edd}) was derived from both emission and absorption lines, indicating these outflows play a significant role in the feedback process to regulate the growth of its black hole as well as host galaxy evolution.Comment: 12 pages, 10 figures. Accepted for publication in The Astrophysical Journa

    The Chandra Source Catalog

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    The Chandra Source Catalog (CSC) is a general purpose virtual X-ray astrophysics facility that provides access to a carefully selected set of generally useful quantities for individual X-ray sources, and is designed to satisfy the needs of a broad-based group of scientists, including those who may be less familiar with astronomical data analysis in the X-ray regime. The first release of the CSC includes information about 94,676 distinct X-ray sources detected in a subset of public ACIS imaging observations from roughly the first eight years of the Chandra mission. This release of the catalog includes point and compact sources with observed spatial extents <~ 30''. The catalog (1) provides access to the best estimates of the X-ray source properties for detected sources, with good scientific fidelity, and directly supports scientific analysis using the individual source data; (2) facilitates analysis of a wide range of statistical properties for classes of X-ray sources; and (3) provides efficient access to calibrated observational data and ancillary data products for individual X-ray sources, so that users can perform detailed further analysis using existing tools. The catalog includes real X-ray sources detected with flux estimates that are at least 3 times their estimated 1 sigma uncertainties in at least one energy band, while maintaining the number of spurious sources at a level of <~ 1 false source per field for a 100 ks observation. For each detected source, the CSC provides commonly tabulated quantities, including source position, extent, multi-band fluxes, hardness ratios, and variability statistics, derived from the observations in which the source is detected. In addition to these traditional catalog elements, for each X-ray source the CSC includes an extensive set of file-based data products that can be manipulated interactively.Comment: To appear in The Astrophysical Journal Supplement Series, 53 pages, 27 figure
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