LLANO DE LOS JUNCOS. TEJEDA [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Cyclone‐Anticyclone Asymmetry of Eddy Detection on Gridded Altimetry Product in the Mediterranean Sea

International audienceWe perform an Observing System Simulation Experiment (OSSE), that simulates the satellite sampling and the mapping procedure on the sea surface of the high-resolution model CROCO-MED60v40, to investigate the reliability and the accuracy of the detected eddies. The main result of this study is a strong cyclone-anticyclone asymmetry of the eddy detection on the altimetry products AVISO/CMEMS in the Mediterranean Sea. Large scale cyclones having a characteristic radius larger than the local deformation radius are much less reliable than large scale anticyclones. We estimate, that less than 60

Selecting parameters for the Rainbow signature scheme

Abstract. Multivariate public key cryptography is one of the main approaches to guarantee the security of communication in a post-quantum world. One of the most promising candidates in this area is the Rainbow signature scheme, which was first proposed by J. Ding and D. Schmidt in 2005. In this paper we develop a model of security for the Rainbow signature scheme. We use this model to find parameters for Rainbow over GF(16), GF(31) and GF(256) which, under certain assumptions, guarantee the security of the scheme for now and the near future

Absence of adynamic bone disease in African-Americans with CKD Stage 5 after 3 years of vitamin D therapy guided by iPTH and the PTH-(1-84)/N-terminally truncated PTH fragments ratio

Background: Secondary hyperparathyroidism is a frequent complication of chronic kidney disease (CKD). The goal of treatment is to achieve circulating levels of parathyroid hormone (PTH) associated without over suppression of bone turnover. This is commonly achieved by treatment with vitamin D analogs. Doses of vitamin D compounds are usually monitored by measurement of circulating levels of PTH. Study design: To prospectively assess the effects on bone histology of two different protocols for dosing vitamin D. Setting and participants: African-American patients from the same geographic area, managed by the same team of physicians in three dialysis clinics were studied. Patients were treated with vitamin D for 3 years and underwent bone biopsies for assessment of bone turnover. Dosing of vitamin D during the 3 years prior to the biopsy was done following two different guidelines. One group was treated following K/ DOQI guidelines adapted to the bio-intact PTH assay (Protocol A), the other group was managed (Protocol B) following K/DOQI guidelines for intact PTH and/or the ratio of PTH-(1-84)/N-terminally truncated fragments (PTH ratio). Predictor: Levels of circulating PTH and/or PTH ratio. Outcome: Prevalence of low bone turnover. Measurements: Qualitative and quantitative assessment of bone histology after tetracycline labeling. Results: 7 out of 22 patients managed following Protocol Awere found to have low bone turnover (32%) by bone histology. None of the 21 patients managed by Protocol B for guidance of vitamin D therapy, had low bone turnover. Limitations: Lack of bone biopsy at the beginning of study. Conclusions: This report indicates that the additional information provided by the PTH ratio represents a distinct advantage in avoiding low bone turnover over the use of a single PTH assay to guide vitamin D dosing in African-American patients with CKD Stage 5 on dialysis. © 2009 Dustri-Verlag Dr. K. Feistle

Impact of assimilation of absolute dynamic topography on Arctic Ocean circulation

Copyright \ua9 2024 Smith, H\ue9bert-Pinard, Gauthier, Roy, Peterson, Veillard, Faug\ue8re, Mulet and Morales Maqueda.The ocean circulation is typically constrained in operational analysis and forecasting systems through the assimilation of sea level anomaly (SLA) retrievals from satellite altimetry. This approach has limited benefits in the Arctic Ocean and surrounding seas due to data gaps caused by sea ice coverage. Moreover, assimilation of SLA in seasonally ice-free regions may be negatively affected by the quality of the Mean Sea Surface (MSS) used to derive the SLA. Here, we use the Regional Ice Ocean Prediction System (RIOPS) to investigate the impact of assimilating Absolute Dynamic Topography (ADT) fields on the circulation in the Arctic Ocean. This approach avoids the use of a MSS and additionally provides information on sea level in ice covered regions using measurements across leads (openings) in the sea ice. RIOPS uses a coupled ice-ocean model on a 3-4 km grid-resolution pan-Arctic domain together with a multi-variate reduced-order Kalman Filter. The system assimilates satellite altimetry and sea surface temperature together with in situ profile observations. The background error is modified to match the spectral characteristics of the ADT fields, which contain less energy at small scales than traditional SLA due to filtering applied to reduce noise originating in the geoid product used. A series of four-year reanalyses demonstrate significant reductions in innovation statistics with important impacts across the Arctic Ocean. Results suggest that the assimilation of ADT can improve circulation and sea ice drift in the Arctic Ocean, and intensify volume transports through key Arctic gateways and resulting exchanges with the Atlantic Ocean. A reanalysis with a modified Mean Dynamic Topography (MDT) is able to reproduce many of the benefits of the ADT but does not capture the enhanced transports. Assimilation of SLA observations from leads in the sea ice appears to degrade several circulation features; however, these results may be sensitive to errors in MDT. This study highlights the large uncertainties that exist in present operational ocean forecasting systems for the Arctic Ocean due to the relative paucity and reduced quality of observations compared to ice-free areas of the Global Ocean. Moreover, this underscores the need for dedicated and focused efforts to address this critical gap in the Global Ocean Observing System