On the Scientific Applications of IGS Products: An Assessment of the Reprocessed TIGA Solutions and Combined Products

Global sea levels have risen since the early 19th century and this rise is likely to accelerate through the 21st century and beyond. Much of the past information on sea level rise stems from the instrumental records of tide gauges, which measure changes in sea level relative to a tide gauge benchmark (TGBM) situated on land. In order to assess regional or global sea level changes the vertical land movements (VLM) at the tide gauge and its TGBM need to be monitored. GNSS, in particular GPS, has been recognized as one space-geodetic technique to provide highly accurate estimates of VLM in a geocentric reference frame for tide gauges and their TGBMs. As it turned out, this scientific application of GNSS poses the most stringent requirements on the consistency and homogeneity on the data, processing strategies, satellite products, bias models and reference frames used in the analysis of GNSS measurements. Under the umbrella of the International GNSS Service (IGS), the Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has the objective to provide highly-accurate positions and VLM estimates for a global network of tide gauges contributing to the Global Sea Level Observing System (GLOSS) and the Permanent Service for Mean Sea Level (PSMSL). As such TIGA forms an important contribution of the IGS to the goals of the Global Geodetic Observing System (GGOS), the Global Climate Observing System (GCOS) and the World Climate Research Programme (WCRP). To achieve the TIGA-WG objectives, five TIGA Analysis Centers (TACs) contributed re-processed global GPS network solutions to TIGA, employing the latest bias models and processing strategies in accordance with the second IGS re-processing campaign (repro2). These individual TAC solutions were then used to compute the combined products by the TIGA Combination Centre (TCC) at the University of Luxembourg using an in-house modified version of the CATREF software package. In this study, we present and internally evaluate the individual TAC and TIGA combined products. We investigate station positions, scale and origin biases, including their frequency content. We also externally evaluate the combined products, particularly the VLM estimates, using solutions from the ITRF2008, ITRF2014 and the glacial isostatic adjustment model ICE-6G (VM5a). Finally, we draw some conclusions on the recent advances and remaining limitations of the various IGS products required for the challenging application to sea level studies

A Global Vertical Land Movement Data Set from a Combination of Global Navigation Satellite System Solutions

Coastal sea-level measurements by tide gauges provide the longest instrumental records of sea-levels with some stretching from the 19th century to present. The derived mean sea-level (MSL) records provide sea-level relative to a nearby tide gauge benchmark (TGBM), which allows for the continuation of this record in time after, for example, equipment modifications. Any changes in the benchmark levels induced by vertical land movements (VLM) affect the MSL records and hence the computed sea-levels. In the past, MSL records affected by VLM were often excluded from further analyses or the VLM were modelled using numerical models of the glacial isostatic adjustment (GIA) process. Over the last two decades Global Navigation Satellite System (GNSS), in particular Global Positioning System (GPS), measurements at or close to tide gauges and the development of the associated processing strategies, have made it possible to obtain estimates of VLM in a geocentric reference system, such as the International Terrestrial Reference Frame release 2008 (ITRF2008) that approach the required accuracy for sea-level studies. Furthermore, the GPS-derived VLM estimates have been shown to improve estimates of sea-level change compared to those using the aforementioned GIA models as these models cannot predict local subsidence or uplift. The International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group has recently re-processed the global GNSS data set from its archive (1000+ stations for 1995-2014) to provide VLM estimates tuned for the sea-level community. To achieve this, five TIGA Analysis Centers (TAC) contributed their reprocessed global GPS network solutions to the WG, all employing the latest bias models and processing strategies in accordance with the second re-processing compaign (repro2) of the IGS. These individual solutions were then combined by the TIGA Combination Center (TCC) to produce, for the first time, a TIGA combined solution (Release 0.99). This combined solution allows an evaluation of each individual TAC solution while also providing a means to gauge the quality and reliability of the combined solution, which is generally regarded as superior to the individual TAC solutions. Using time series analysis methods, estimates of VLM can then be derived from the daily position estimates, which are sub-sequentially employed to investigate coastal sea-levels. In this study, we show results from the evaluation of the relevant solutions, provide an evaluation of the TIGA VLM estimates and give examples of their impact on sea-level estimates for selected tide gauges from around the world. The TAC and TIGA combined solutions, as well as the derived VLM data sets are available from the IGS TIGA WG and will be accessible through SONEL (www.sonel.org) in the near future

Myc and cell cycle control

Soon after the discovery of the Myc gene (c-Myc), it became clear thatMyc expression levels tightly correlate to cell proliferation. The entry in cell cycle of quiescent cells upon Myc enforced expression has been described in manymodels. Also, the downregulation or inactivation ofMyc results in the impairment of cell cycle progression. Given the frequent deregulation of Myc oncogene in human cancer it is important to dissect out the mechanisms underlying the role ofMyc on cell cycle control. Several parallel mechanisms account forMyc-mediated stimulation of the cell cycle. First,most of the critical positive cell cycle regulators are encoded by genes induced byMyc. These Myc target genes include Cdks, cyclins and E2F transcription factors. Apart from its direct effects on the transcription, Myc is able to hyperactivate cyclin/Cdk complexes through the induction of Cdk activating kinase (CAK) and Cdc25 phosphatases. Moreover, Myc antagonizes the activity of cell cycle inhibitors as p21 and p27 through different mechanisms. Thus, Myc is able to block p21 transcription or to induce Skp2, a protein involved in p27 degradation. Finally, Myc induces DNA replication by binding to replication origins and by upregulating genes encoding proteins required for replication initiation. Myc also regulates genes involved in the mitotic control. A promising approach to treat tumors with deregulated Myc is the synthetic lethality based on the inhibition of Cdks. Thus, the knowledge of the Myc-dependent cell cycle regulatory mechanisms will help to discover new therapeutic approaches directed against malignancies with deregulated Myc. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.The work in the laboratory of the authors is funded by grants SAF11-23796 from Spanish Ministry of Industry and Innovation, and ISCIII-RETIC RD12/0036/0033 from Spanish Ministry of Health to JL, and FIS 11/00397 to MDD. GB is recipient of a fellowship form the FPI Program. We apologize to colleagues whose work has not been cited in the form of their original papers but in reviews and whose work has not been discussed due to space limitations or unintentional omission

The comparative responsiveness of Hospital Universitario Princesa Index and other composite indices for assessing rheumatoid arthritis activity

Objective To evaluate the responsiveness in terms of correlation of the Hospital Universitario La Princesa Index (HUPI) comparatively to the traditional composite indices used to assess disease activity in rheumatoid arthritis (RA), and to compare the performance of HUPI-based response criteria with that of the EULAR response criteria. Methods Secondary data analysis from the following studies: ACT-RAY (clinical trial), PROAR (early RA cohort) and EMECAR (pre-biologic era long term RA cohort). Responsiveness was evaluated by: 1) comparing change from baseline (Delta) of HUPI with Delta in other scores by calculating correlation coefficients; 2) calculating standardised effect sizes. The accuracy of response by HUPI and by EULAR criteria was analyzed using linear regressions in which the dependent variable was change in global assessment by physician (Delta GDA-Phy). Results Delta HUPI correlation with change in all other indices ranged from 0.387 to 0.791); HUPI's standardized effect size was larger than those from the other indices in each database used. In ACT-RAY, depending on visit, between 65 and 80% of patients were equally classified by HUPI and EULAR response criteria. However, HUPI criteria were slightly more stringent, with higher percentage of patients classified as non-responder, especially at early visits. HUPI response criteria showed a slightly higher accuracy than EULAR response criteria when using Delta GDA-Phy as gold standard. Conclusion HUPI shows good responsiveness in terms of correlation in each studied scenario (clinical trial, early RA cohort, and established RA cohort). Response criteria by HUPI seem more stringent than EULAR''s

SARI : un nouvel outil en ligne pour le traitement interactif des séries temporelles

L'outil SARI permet aux utilisateurs de visualiser les séries dans un navigateur Web, de retirer des discontinuités et points aberrants, d'ajuster des modèles de façon interactive et de sauvegarder les résultats. Une liste exhaustive des fonctionnalités a été implémentée pour aider l'utilisateur dans l'extraction de l'information recherchée

SARI : un nouvel outil en ligne pour le traitement interactif des séries temporelles

L'outil SARI permet aux utilisateurs de visualiser les séries dans un navigateur Web, de retirer des discontinuités et points aberrants, d'ajuster des modèles de façon interactive et de sauvegarder les résultats. Une liste exhaustive des fonctionnalités a été implémentée pour aider l'utilisateur dans l'extraction de l'information recherchée

SARI : logiciel interactif et en ligne d'analyse de séries chronologiques

GNSS position time series contain signals induced by earth deformation, but also by systematic errors, at different time scales, from sub-daily tidal deformation to inter-annual surface-loading deformation and secular tectonic plate rotation. SARI allows users to visualize GNSS position time series, but also any other series, and interactively remove outliers and discontinuities, fit models and save the results. A comprehensive list of features is included to help the user extracting relevant information from the series, including spectral analysis with the Lomb–Scargle periodogram and wavelet transform, signal filtering with the Kalman filter and the Vondrák smoother, and estimation of the time-correlated stochastic noise of the residuals. The software can be run on a local machine if all the package dependencies are satisfied or remotely via a public web server with no requirement other than having an internet connection.This poster was presented at the Résif Scientific and Technical Meetings held in Biarritz in November 2019. The French seismological and geodetic network Résif is a national research infrastructure dedicated to the observation and understanding of the structure and dynamics of the Internal Earth. Résif is based on high-tech observation networks, composed of seismological, geodetic and gravimetric instruments deployed in a dense manner throughout France. The data collected make it possible to study with high spatial and temporal resolution the deformation of the ground, surface and deep structures, seismicity on a local and global scale and natural hazards, and more particularly seismic events, on French territory. Résif is part of the European (EPOS - European Plate Observing System) and global systems of instruments used to image the Earth's interior as a whole and to study many natural phenomena.SARI permet aux utilisateurs de visualiser des séries chronologiques, à partir des positions GNSS ou de toute autre série, et de supprimer interactivement les valeurs aberrantes et les discontinuités, d'ajuster les modèles paramétriques et non paramétriques et de sauvegarder les résultats. Une liste complète de caractéristiques est incluse pour aider l'utilisateur à extraire l'information pertinente de séries d'échantillons inégaux, y compris l'analyse spectrale avec le parodogramme de Lomb et la transformée en ondelettes ; le filtrage du signal avec le filtre de Kalman et le lisseur de Vondrák ; l'estimation du bruit stochastique des résidus lié au temps et la détection automatique du décalage. SARI peut être exécuté sur un serveur Web public sans autre exigence qu'une connexion Internet. Ce poster a été présenté aux Rencontres scientifiques et techniques Résif qui se sont déroulées à Biarritz en novembre 2019. Résif est une infrastructure de recherche nationale dédiée à l’observation et la compréhension de la structure et de la dynamique Terre interne. Résif se base sur des réseaux d’observation de haut niveau technologique, composés d’instruments sismologiques, géodésiques et gravimétriques déployés de manière dense sur tout le territoire français. Les données recueillies permettent d’étudier avec une haute résolution spatio-temporelle la déformation du sol, les structures superficielles et profondes, la sismicité à l’échelle locale et globale et les aléas naturels, et plus particulièrement sismiques, sur le territoire français. Résif s’intègre aux dispositifs européens (EPOS - European Plate Observing System) et mondiaux d’instruments permettant d’imager l’intérieur de la Terre dans sa globalité et d’étudier de nombreux phénomènes naturels

Geodetic secular velocity errors due to interannual surface loading deformation,

International audienceGeodetic vertical velocities derived from data as short as 3 yr are often assumed to be representative of linear deformation over past decades to millennia. We use two decades of surface loading deformation predictions due to variations of atmospheric, oceanic and continental water mass to assess the effect on secular velocities estimated from short time-series. The interannual deformation is time-correlated at most locations over the globe, with the level of correlation depending mostly on the chosen continental water model. Using the most conservative loading model and 5-yr-long time-series, we found median vertical velocity errors of 0.5 mm yr−1 over the continents (0.3 mm yr−1 globally), exceeding 1 mm yr−1 in regions around the southern Tropic. Horizontal velocity errors were seven times smaller. Unless an accurate loading model is available, a decade of continuous data is required in these regions to mitigate the impact of the interannual loading deformation on secular velocities

Geodetic secular velocity errors due to interannual surface loading deformation,

International audienceGeodetic vertical velocities derived from data as short as 3 yr are often assumed to be representative of linear deformation over past decades to millennia. We use two decades of surface loading deformation predictions due to variations of atmospheric, oceanic and continental water mass to assess the effect on secular velocities estimated from short time-series. The interannual deformation is time-correlated at most locations over the globe, with the level of correlation depending mostly on the chosen continental water model. Using the most conservative loading model and 5-yr-long time-series, we found median vertical velocity errors of 0.5 mm yr−1 over the continents (0.3 mm yr−1 globally), exceeding 1 mm yr−1 in regions around the southern Tropic. Horizontal velocity errors were seven times smaller. Unless an accurate loading model is available, a decade of continuous data is required in these regions to mitigate the impact of the interannual loading deformation on secular velocities