4,614 research outputs found

    Testing the Unbiasedness Hypothesis in the Forward Foreign Exchange Market: A Specification Analysis

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    This paper evaluates two popular regression methods of testing the unbiasedness hypothesis in the forward foreign exchange market. For the 30-day Canada/United States forward foreign exchange market, the evidence overwhelmingly indicates that it is inappropriate to treat the structure of the systematic and stochastic components of the test relations as constant over time. Hence, conclusions inferred from parameter significance testing based upon full-sample estimation can be very misleading. Accordingly, we argue for a specification analysis of the test relations, and more explicit modelling of market fundamentals.The financial support of the Social Sciences and Humanities Research Council of Canada and the Advisory Research Committee of Queen's University is acknowledged

    A real-time prediction of UTC

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    The reference time scale for all scientific and technologic applications on the Earth, the Universal Coordinated Time (UTC), must be as stable, reliable, and accurate as possible. With this in view the BIPM and before it the BIH, have always calculated and then disseminated UTC with a delay of about 80 days. There are three fundamental reasons for doing this: (1) It takes some weeks for data, gathered from some 200 clocks spread world-wide, to be collected and for errors to be eliminated; (2) changes in clock rates can only be measured with high precision well after the fact; and (3) the measurement noise originating in time links, in particular using Loran-C, is smoothed out only when averaging over an extended period. Until mid-1992, the ultimate stability of UTC was reached at averaging times of about 100 days and corresponded to an Allan deviation sigma(sub y)(tau) of about 1,5x10(exp -14) then compared to the best primary clock in the world, the PTB CS2. For several years now, a predicted UTC has been computed by the USNO through an extrapolation of the values as published in deferred time by the BIPM. This is made available through the USNO Series 4, through the USNO Automated Data Service, and through GPS signals. Due to the instability of UTC, the poor predictability of the available clocks, and the intentional SA degradation of GPS signals, the real-time access to this extrapolated UTC has represented the true deferred-time UTC only to within several hundreds of nanoseconds

    Shock compression and isentropic release of granite

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    New equation of state data for a weathered granite shocked to about 125 GPa are reported and combined with the Westerly granite data of McQueen, Marsh & Fritz (1967). The shock velocity (U_s)-particle velocity (U_p) relations can be fitted with two linear regressions: U_s= 4.40 + 0.6U_p for a range of U_p up to about 2 km s^(-1) and U_s= 2.66 + 1.49U_p for a range of about 2 to 5 km s^(-1). The third-order Birch-Murnaghan equation of state parameters are K_(os) = 51-57 GPa and K'_(os) = 1.4-1.8 for the low-pressure regime and K_(os) = 251 ± 30 GPa and an assumed K'_(os) = 4 for the high-pressure regime. Compressive waveforms in dry and water-saturated granite were measured at 10-15 GPa using the VISAR technique. The measured wave profiles were successfully modelled using a Maxwellian stress-relaxation material model. Water-saturated granite is characterized by a ~25 per cent lower yield strength and a ~75 per cent longer material relaxation time than dry granite

    Identification of a non-purple tartrate-resistant acid phosphatase: an evolutionary link to Ser/Thr protein phosphatases?

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    BACKGROUND Tartrate-resistant acid phosphatases (TRAcPs), also known as purple acid phosphatases (PAPs), are a family of binuclear metallohydrolases that have been identified in plants, animals and fungi. The human enzyme is a major histochemical marker for the diagnosis of bone-related diseases. TRAcPs can occur as a small form possessing only the ~35 kDa catalytic domain, or a larger ~55 kDa form possessing both a catalytic domain and an additional N-terminal domain of unknown function. Due to its role in bone resorption the 35 kDa TRAcP has become a promising target for the development of anti-osteoporotic chemotherapeutics. FINDINGS A new human gene product encoding a metallohydrolase distantly related to the ~55 kDa plant TRAcP was identified and characterised. The gene product is found in a number of animal species, and is present in all tissues sampled by the RIKEN mouse transcriptome project. Construction of a homology model illustrated that six of the seven metal-coordinating ligands in the active site are identical to that observed in the TRAcP family. However, the tyrosine ligand associated with the charge transfer transition and purple color of TRAcPs is replaced by a histidine. CONCLUSION The gene product identified here may represent an evolutionary link between TRAcPs and Ser/Thr protein phosphatases. Its biological function is currently unknown but is unlikely to be associated with bone metabolism.This work was funded by the Royal Society of Tropical Medicine and Hygiene through a Dennis Burkitt Fellowship to JJM. ARD is supported by the Economic and Social Research Council. JJM is supported by a Wellcome Trust Research Training Fellowship (GR074833MA)

    Collaborative Tagging of Phenotypic Data for Clinical and Translational Sciences

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    To fully understand results derived from genetic research, a patient’s genotype data must be integrated with other information about the individual (vital signs, height/weight, lab values, disease history – the phenotype of the patient) that can be obtained through clinical records. Within the clinical and translational sciences awards (CTSA), significant effort has been supported to expand translational research through the creation and mining of a phenotypic data warehouse (i2b2) that can be further linked to genotype data. However, this is just a first step towards meaningful use of the available information. Much of the information in electronic clinical records is trapped in unstructured free text, and inaccessible. Transforming this information into usable data has great potential to improve personalized healthcare and enhance the scientific enterprise. We are using “collaborative tagging,” a newer web 2.0 phenomenon used to structure information for accessibility online in which groups of individuals can add any word or phrase as a tag to identify an object (a weblog entry, a picture, etc.). Because taggers create whatever they deem as the most important tags, and are not required to select from a complex tree of predetermined tags, folksonomies can be a more palatable form of data entry than selected from a complex, predetermined list of tags. We will present our results on tagging of clinical notes by UMMS and community-based providers. This presentation was part of the retreat mini-symposium entitled: Data-Driven Approaches for Health Informatics

    Meeting irrigation demands in a water-challenged environment

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    Presented at Meeting irrigation demands in a water-challenged environment: SCADA and technology: tools to improve production: a USCID water management conference held on September 28 - October 1, 2010 in Fort Collins, Colorado.Includes bibliographical references.Accurate estimates of spatially distributed evapotranspiration (ET) using remote sensing inputs could help improve crop water management, the assessment of regional drought conditions, irrigation efficiency, ground water depletion, and the verification of the use of water rights over large irrigated areas. In this study, ET was mapped using surface reflectance and radiometric temperature images from the Landsat 5 satellite in a surface energy budget algorithm driven by a surface aerodynamic temperature (SAT_ET) model. The SAT_ET model was developed using surface temperature, horizontal wind speed, air temperature and crop biophysical characteristic measured over an irrigated alfalfa field in Southeastern Colorado. Estimates of the remote sensing-based ET for a 4.0 hectare alfalfa field and a 3.5 hectare oats field, during the 2009 cropping season, were evaluated using two monolithic weighing lysimeters located at the Colorado State University Arkansas Valley Research Center (AVRC) in Rocky Ford, Colorado. Although the overall model performance was encouraging, results indicated that the SAT_ET model performed well under dry atmospheric and soil conditions and less accurately under high air relative humidity and soil water content conditions. These findings are evidence that SAT_ET needs to be further developed to perform better under a range of environmental and atmospheric conditions
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