2,587 research outputs found

    REVISITING THE ROLE OF OBSERVATION SESSION DURATION ON PRECISE POINT POSITIONING ACCURACY USING GIPSY/OASIS II SOFTWARE

    Get PDF
    The accuracy of GPS precise point positioning (PPP) was previously modelled as a function of the observing session duration T. The NASA, JPL’s software GIPSY OASIS II (GOA-II) along with the legacy products was used to process the GPS data. The original accuracy model is not applicable anymore because JPL started releasing its products using new modelling and analysis strategies as of August 2007, and the legacy products are no longer available. The developments mainly comprise the new orbit and clock determination strategy, second order ionosphere modelling, and single station ambiguity resolution. Previously, the PPP accuracy was studied using v 4.0 of the GOA-II. The accuracy model showed coarser results compared to that of the relative positioning. Here, we processed the data of the International GNSS Service (IGS) stations to refine the accuracy of GOA-II PPP from version 6.3. Considering the above changes we refined the accuracy of PPP. First we modified the previous model used for the accuracy assessment. Then we tested out this model using straightforward polynomial and logarithmic models. The tests indicate the previous formulation still satisfactorily models the accuracy using refined coefficient values Sn = 7.8 mm, Se = 6.8 mm, Sv = 29.9 mm for T ≥ 2 h

    Heteromerization Modulates mu Opioid Receptor Functional Properties in vivo.

    Get PDF
    Mu opioid receptors modulate a large number of physiological functions. They are in particular involved in the control of pain perception and reward properties. They are also the primary molecular target of opioid drugs and mediate their beneficial analgesic effects, euphoric properties as well as negative side effects such as tolerance and physical dependence. Importantly, mu opioid receptors can physically associate with another receptor to form a novel entity called heteromer that exhibits specific ligand binding, signaling, and trafficking properties. As reviewed here, in vivo physical proximity has now been evidenced for several receptor pairs, subsequent impact of heteromerization on native mu opioid receptor signaling and trafficking identified and a link to behavioral changes established. Selective targeting of heteromers as a tool to modulate mu opioid receptor activity is therefore attracting growing interest and raises hopes for innovative therapeutic strategies.journal articlereview20182018 11 13importe

    ON THE PERFORMANCE OF GNSS LEVELLING OVER STEEP SLOPES

    Get PDF
    In geodetic applications variety, one of the main current focuses is recently to determine the heights of ground stations with high accuracy. Specially the possibility of acquiring 3D information of the point positioning with high accuracy is opening up new strategies of investigating the heighting. Global Navigation Satellite System (GNSS) for 3D positioning is undergoing rapid developments andGNSS heighting can be an alternative to terrestrial techniques of height measurements. This paper presents a research study on the use of GNSS heighting in the case of steep slopes and multipath issue. Short baseline solution strategieswere performed by using Bernese Software v. 5.0. The analysis results are also compared to the results of techniques of the terrestrial levelling. The results showthat GNSS can be used as an practical surveying method to the terrestrial levelling with comparable accuracies. Furthermore, one can save up to 1 hour using GNSSinstead of geometric levelling over a steep slope of a 100 m. On the other hand, as usual multipath is the primary error source decreasing the efficiency of GNSS, and it has been studied experimentally in this paper

    Video Coding With Low-Complexity Directional Adaptive Interpolation Filters

    Full text link

    Probability densities for the sums of iterates of the sine-circle map in the vicinity of the quasi-periodic edge of chaos

    Full text link
    We investigate the probability density of rescaled sum of iterates of sine-circle map within quasi-periodic route to chaos. When the dynamical system is strongly mixing (i.e., ergodic), standard Central Limit Theorem (CLT) is expected to be valid, but at the edge of chaos where iterates have strong correlations, the standard CLT is not necessarily to be valid anymore. We discuss here the main characteristics of the central limit behavior of deterministic dynamical systems which exhibit quasi-periodic route to chaos. At the golden-mean onset of chaos for the sine-circle map, we numerically verify that the probability density appears to converge to a q-Gaussian with q<1 as the golden mean value is approached.Comment: 7 pages, 7 figures, 1 tabl

    Experimental and Numerical Dynamic Properties of Two Timber Footbridges Including Seasonal Efects

    Get PDF
    This paper deals with experimental and numerical dynamic analyses of two timber footbridges. Both bridges have a span of 35 m and consist of a timber deck supported by two timber arches. The main purpose is to investigate if the dynamic properties of the bridges are season dependent. To this end, experimental tests are performed during a cold day in winter and a warm day in spring in Sweden. The frst bending and transverse mode frequencies increase 22% and 44%, respectively, due to temperature efects in the case of Vega Bridge. In the case of Hägernäs bridge, the corresponding values are 5% and 26%. For both bridges, the measured damping coefcients are similar in winter and spring. However, the damping coeffcients for the frst bending and transverse modes are diferent for both footbridges: about 1% for the Hägernäs bridge and 3% for the Vega bridge. Finite-element models are also implemented. Both numerical and experimental results show good correspondence. From the analyses performed, it is concluded that the connections between the diferent components of the bridges have a signifcant infuence on the dynamic properties. In addition, the variation of the stifness for the asphalt layer can explain the diferences found in the natural frequencies between spring and winter. However, due to the uncertainties in the modelling of the asphalt layer, this conclusion must be taken with caution

    Orange pickeringite from the algares 30-level adit, aljustrel mine, iberian pyrite belt, portugal

    Get PDF
    Funding Information: Funding: Funding from FEDER (Fundo Europeu de Desenvolvimento Regional)/INTERREG POCTEP GEO-FPI - (Ref. 0052-GEO-FPI-5-E) and EXPLORA, Op ALT20-03-0145-FEDER-000025. Funding by Alentejo 2020, Portugal 2020 and the European Union (ERDF) is acknowledged. J.P. Veiga acknowledges FEDER funds through the COMPETE 2020 Programme and National Funds through the FCT-Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2019, and SFRH/BD/145308/2019 (F.Carvalho) plus UIDP/50025/2020 (U.D. Menda), and funding from the European Institute of Innovation and Technology (EIT), a body of the European Union, under Horizon 2020, the EU Framework Programme for Research and Innovation, through the MineHeritage Project (PA 18111).The sheltered environment of the Algares +30 level adit (underground mine gallery) contributes to the preservation of secondary water-soluble minerals formed on the tunnel walls. The massive sulphide and related stockwork zone are hosted by the Mine Tuff volcanic unit and are exposed in the walls of the gallery, showing intense oxidation and hydrothermal alteration. Minerals from the halotrichite group were identified on the efflorescent salts, typically white fine-acicular crystals but also on aggregates with dark orange/brownish colour. Mineral characterization was performed using several methods and analytical techniques (XRD, XRF-WDS, SEM-EDS, DTA-TG), and the chemical formulas were calculated maintaining the ratio A:B∼= 1:2 in accordance with the general formula of the halotrichite group, AB2 (SO4 )4·22H2 O. This methodology allowed the assignment of the orange colour to the presence of trivalent iron on iron-rich pickeringite in partial substitution of aluminium.publishersversionpublishe

    Spatial dependence in the growth process and implications for convergence rate: evidence on Vietnamese provinces

    Get PDF
    Existing studies on Vietnamese provinces (e.g., Anwar and Nguyen, 2010) tend to assume that province-specific growth is independent of that in its neighbours. However, many studies analysing regional economic growth in China, Brazil and Mexico report the existence of spatial spill-over effects. This paper investigates whether this is the case for 60 Vietnamese provinces for the time-period 1999-2010, using a system-GMM estimator and a Solow growth model augmented with human and physical capital and spatial lag covariates. We report that spatial dependence is a significant determinant of growth and conditional convergence in Vietnamese provinces. We also demonstrate that the rate of convergence decreases as the distance between neighbouring provinces increases. Given these findings, we recommend testing for spatial dependence in growth models for Vietnam and beyond to avoid omitted variable bias and inform evidence-based regional policies that take account of spatial externalities
    corecore