Somali Current rings in the eastern Gulf of Aden

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C09039, doi:10.1029/2005JC003338.New satellite-based observations reveal that westward translating anticyclonic rings are generated as a portion of the Somali Current accelerates northward through the Socotra Passage near the mouth of the Gulf of Aden. Rings thus formed exhibit azimuthal geostrophic velocities exceeding 50 cm/s, are comparable in overall diameter to the width of the Gulf of Aden (250 km), and translate westward into the gulf at 5–8 cm/s. Ring generation is most notable in satellite ocean color imagery in November immediately following the transition between southwest (boreal summer) and northeast (winter) monsoon regimes. The observed rings contain anomalous fluid within their core which reflects their origin in the equator-crossing Somali Current system. Estimates of Socotra Passage flow variability derived from satellite altimetry provide evidence for a similar ring generation process in May following the winter-to-summer monsoon transition. Cyclonic recirculation eddies are observed to spin up on the eastern flank of newly formed rings with the resulting vortex pair translating westward together. Recent shipboard and Lagrangian observations indicate that vortices of both sign have substantial vertical extent and may dominate the lateral circulation at all depths in the eastern Gulf of Aden.This investigation is a component of the Red Sea Outflow Experiment (REDSOX) sponsored by the U.S. National Science Foundation through grants OCE 98-18464 and OCE 04-24647 to the Woods Hole Oceanographic Institution and OCE 98-19506 and OCE 03-51116 to the University of Miami

Dynamics of Wind Setdown at Suez and the Eastern Nile Delta

BACKGROUND: Wind setdown is the drop in water level caused by wind stress acting on the surface of a body of water for an extended period of time. As the wind blows, water recedes from the upwind shore and exposes terrain that was formerly underwater. Previous researchers have suggested wind setdown as a possible hydrodynamic explanation for Moses crossing the Red Sea, as described in Exodus 14. METHODOLOGY/PRINCIPAL FINDINGS: This study analyzes the hydrodynamic mechanism proposed by earlier studies, focusing on the time needed to reach a steady-state solution. In addition, the authors investigate a site in the eastern Nile delta, where the ancient Pelusiac branch of the Nile once flowed into a coastal lagoon then known as the Lake of Tanis. We conduct a satellite and modeling survey to analyze this location, using geological evidence of the ancient bathymetry and a historical description of a strong wind event in 1882. A suite of model experiments are performed to demonstrate a new hydrodynamic mechanism that can cause an angular body of water to divide under wind stress, and to test the behavior of our study location and reconstructed topography. CONCLUSIONS/SIGNIFICANCE: Under a uniform 28 m/s easterly wind forcing in the reconstructed model basin, the ocean model produces an area of exposed mud flats where the river mouth opens into the lake. This land bridge is 3-4 km long and 5 km wide, and it remains open for 4 hours. Model results indicate that navigation in shallow-water harbors can be significantly curtailed by wind setdown when strong winds blow offshore

Management of osteoporosis in central and eastern Europe (CEE): conclusions of the “2nd Summit on Osteoporosis—CEE”, 21–22 November 2008, Warsaw, Poland

In November 2008, the “2nd Summit on Osteoporosis—Central and Eastern Europe (CEE)” was held in Warsaw, Poland. Discussions at this meeting focused on the identification and discussion of diagnostic, preventive, and therapeutic measures used in CEE. Evaluated information was used to identify issues regarding diagnosis and therapy of osteoporosis in these countries to facilitate the subsequent setup of appropriate support and development strategies. The main debate was structured according to the following five subjects: (1) present status and future perspectives for implementation of FRAX® into local (CEE) diagnostic algorithms, (2) principles of drug selection in osteoporosis treatment in CEE countries, (3) nonpharmacological interventions in osteoporosis treatment and prophylaxis in CEE countries, (4) treatment benefit evaluation, and (5) cost–effectiveness and evaluation of reimbursement policies in CEE countries. The most important and substantial comments of the delegates are summarized in the present article. The multinational panel of experts with representatives from many CEE countries as well as Austria and Switzerland made the “2nd Summit on Osteoporosis—CEE” a perfect platform to identify issues and needs regarding diagnosis and therapy of osteoporosis as well as the cost–effectiveness of osteoporosis management in CEE countries. The information gained will serve as a basis for the development of strategies to resolve the identified issues at the “3rd Summit on Osteoporosis—CEE” in November 2009

Chitosan particles agglomerated scaffolds for cartilage and osteochondral tissue engineering approaches with adipose tissue derived stem cells

It is well accepted that natural tissue regeneration is unlikely to occur if the cells are not supplied with an extracellular matrix (ECM) substitute. With this goal, several different methodologies have been used to produce a variety of 3D scaffolds as artificial ECM substitutes suitable for bone and cartilage tissue engineering. Furthermore, osteochondral tissue engineering presents new challenges since the combination of scaffolding and co-culture requirements from both bone and cartilage applications is required in order to achieve a successful osteochondral construct. In this paper, an innovative processing route based on a chitosan particles aggregation methodology for the production of cartilage and osteochondral tissue engineering scaffolds is reported. An extensive characterization is presented including a morphological evaluation using Micro-Computed Tomography (μCT) and 3D virtual models built with an image processing software. Mechanical and water uptake characterizations were also carried out, evidencing the potential of the developed scaffolds for the proposed applications. Cytotoxicity tests show that the developed chitosan particles agglomerated scaffolds do not exert toxic effects on cells. Furthermore, osteochondral bilayered scaffolds could also be developed. Preliminary seeding of mesenchymal stem cells isolated from human adipose tissue was performed aiming at developing solutions for chondrogenic and osteogenic differentiation for osteochondral tissue engineering applications.Fundação para a Ciência e a Tecnologia (FCT)European NoE EXPERTISSUES (NMP3-CT-2004-500283)European STREP Project HIPPOCRATES (NMP3-CT-2003-505758

Mississippi River and Sea Surface Height Effects on Oil Slick Migration

Millions of barrels of oil escaped into the Gulf of Mexico (GoM) after the 20 April, 2010 explosion of Deepwater Horizon (DH). Ocean circulation models were used to forecast oil slick migration in the GoM, however such models do not explicitly treat the effects of secondary eddy-slopes or Mississippi River (MR) hydrodynamics. Here we report oil front migration that appears to be driven by sea surface level (SSL) slopes, and identify a previously unreported effect of the MR plume: under conditions of relatively high river discharge and weak winds, a freshwater mound can form around the MR Delta. We performed temporal oil slick position and altimeter analysis, employing both interpolated altimetry data and along-track measurements for coastal applications. The observed freshwater mound appears to have pushed the DH oil slick seaward from the Delta coastline. We provide a physical mechanism for this novel effect of the MR, using a two-layer pressure-driven flow model. Results show how SSL variations can drive a cross-slope migration of surface oil slicks that may reach velocities of order km/day, and confirm a lag time of order 5–10 days between mound formation and slick migration, as observed form the satellite analysis. Incorporating these effects into more complex ocean models will improve forecasts of slick migration for future spills. More generally, large SSL variations at the MR mouth may also affect the dispersal of freshwater, nutrients and sediment associated with the MR plume

Circulating KCNH2 Current-Activating Factor in Patients with Heart Failure and Ventricular Tachyarrhythmia

It is estimated that approximately half of the deaths in patients with HF are sudden and that the most likely causes of sudden death are lethal ventricular tachyarrhythmias such as ventricular tachycardia (VT) or fibrillation (VF). However, the precise mechanism of ventricular tachyarrhythmias remains unknown. The KCNH2 channel conducting the delayed rectifier K(+) current (I(Kr)) is recognized as the most susceptible channel in acquired long QT syndrome. Recent findings have revealed that not only suppression but also enhancement of I(Kr) increase vulnerability to major arrhythmic events, as seen in short QT syndrome. Therefore, we investigated the existence of a circulating KCNH2 current-modifying factor in patients with HF.We examined the effects of serum of HF patients on recombinant I(Kr) recorded from HEK 293 cells stably expressing KCNH2 by using the whole-cell patch-clamp technique. Study subjects were 14 patients with non-ischemic HF and 6 normal controls. Seven patients had a history of documented ventricular tachyarrhythmias (VT: 7 and VF: 1). Overnight treatment with 2% serum obtained from HF patients with ventricular arrhythmia resulted in a significant enhancement in the peaks of I(Kr) tail currents compared to the serum from normal controls and HF patients without ventricular arrhythmia.Here we provide the first evidence for the presence of a circulating KCNH2 channel activator in patients with HF and ventricular tachyarrhythmias. This factor may be responsible for arhythmogenesis in patients with HF

Transcription profiling of HCN-channel isotypes throughout mouse cardiac development

Hyperpolarization-activated ion channels, encoded by four mammalian genes (HCN1-4), contribute in an important way to the cardiac pacemaker current If. Here, we describe the transcription profiles of the four HCN genes, the NRSF, KCNE2 and Kir2.1 genes from embryonic stage E9.5 dpc to postnatal day 120 in the mouse. Embryonic atrium and ventricle revealed abundant HCN4 transcription but other HCN transcripts were almost absent. Towards birth, HCN4 was downregulated in the atrium and almost vanished from the ventricle. After birth, however, HCN isotype transcription changed remarkably, showing increased levels of HCN1, HCN2 and HCN4 in the atrium and of HCN2 and HCN4 in the ventricle. HCN3 showed highest transcription at early embryonic stages and was hardly detectable thereafter. At postnatal day 10, HCN4 was highest in the sinoatrial node, being twofold higher than HCN1 and fivefold higher than HCN2. In the atrium, HCN4 was similar to HCN1 and sevenfold higher than HCN2. In the ventricle, in contrast, HCN2 was sixfold higher than HCN4, while HCN1 was absent. Subsequently all HCN isotype transcripts declined to lower adult levels, while ratios of HCN isotypes remained stable. In conclusion, substantial changes of HCN isotype transcription throughout cardiac development suggest that a regulated pattern of HCN isotypes is required to establish and ensure a stable heart rhythm. Furthermore, constantly low HCN transcription in adult myocardium may be required to prevent atrial and ventricular arrhythmogenesis