Origin of the Sinai-Negev erg, Egypt and Israel: mineralogical and geochemical evidence for the importance of the Nile and sea level history

The Sinai-Negev erg occupies an area of 13,000 km2 in the deserts of Egypt and Israel. Aeolian sand of this erg has been proposed to be derived from the Nile Delta, but empirical data supporting this view are lacking. An alternative source sediment is sand from the large Wadi El Arish drainage system in central and northern Sinai. Mineralogy of the Negev and Sinai dunes shows that they are high in quartz, with much smaller amounts of K-feldspar and plagioclase. Both Nile Delta sands and Sinai wadi sands, upstream of the dunes, also have high amounts of quartz relative to K-feldspar and plagioclase. However, Sinai wadi sands have abundant calcite, whereas Nile Delta sands have little or no calcite. Overall, the mineralogical data suggest that the dunes are derived dominantly from the Nile Delta, with Sinai wadi sands being a minor contributor. Geochemical data that proxy for both the light mineral fraction (SiO2/10-Al2O3 + Na2O + K2O-CaO) and heavy mineral fraction (Fe2O3-MgO-TiO2) also indicate a dominant Nile Delta source for the dunes. Thus, we report here the first empirical evidence that the Sinai-Negev dunes are derived dominantly from the Nile Delta. Linkage of the Sinai-Negev erg to the Nile Delta as a source is consistent with the distribution of OSL ages of Negev dunes in recent studies. Stratigraphic studies show that during the Last Glacial period, when dune incursions in the Sinai-Negev erg began, what is now the Nile Delta area was characterized by a broad, sandy, minimally vegetated plain, with seasonally dry anastomosing channels. Such conditions were ideal for providing a ready source of sand for aeolian transport under what were probably much stronger glacial-age winds. With the post-glacial rise in sea level, the Nile River began to aggrade. Post-glacial sedimentation has been dominated by fine-grained silts and clays. Thus, sea level, along with favorable climatic conditions, emerges as a major influence on the timing of dune activity in the Sinai-Negev erg, through its control on the supply of sand from the Nile Delta. The mineralogy of the Sinai-Negev dunes is also consistent with a proposed hypothesis that these sediments are an important source of loess in Israel

Fine dust emissions from active sands at coastal Oceano Dunes, California

Sand dunes and other active sands generally have a low content of fine grains and, therefore, are not considered to be major dust sources in current climate models. However, recent remote sensing studies have indicated that a surprisingly large fraction of dust storms are generated from regions covered by sand dunes, leading these studies to propose that sand dunes might be globally relevant sources of dust. To help understand dust emissions from sand dunes and other active sands, we present in situ field measurements of dust emission under natural saltation from a coastal sand sheet at Oceano Dunes in California. We find that saltation drives dust emissions from this setting that are on the low end of the range in emissions produced by non-sandy soils for similar wind speed. Laboratory analyses of sand samples suggest that these emissions are produced by aeolian abrasion of feldspars and removal of clay-mineral coatings on sand grain surfaces. We further find that this emitted dust is substantially finer than dust emitted from non-sandy soils, which could enhance its downwind impacts on human health, the hydrological cycle, and climate.</p

Comparison of Helicobacter Pylori Genotypes Obtained from the Oropharynx and Stomach of the Same Individuals -A Pilot Study

R e c e i ve d M a rc h 3 , 2 0 12 ; A c c e p t e d Ju n e 2 5 , 2 0 1 2 . Key words: Helicobacter pylori -Real-time PCR -Genotyping -OropharynxStomach -Comparison Abstract: Helicobacter pylori has been recently detected in the oral cavity and oropharynx. However, the role it plays in oral and oropharyngeal pathogenesis remains unclear. The virulence of H. pylori strains can be distinguished according to the virulence factors genes carried. Our research has been focused on realtime PCR analysis of cagA and vacA genes of H. pylori strains in tonsils and tonsillar squamous cell cancer and their comparison with H. pylori strains obtained fro

Erratum: The solar orbiter radio and plasma waves (RPW) instrument (Astronomy and Astrophysics (2020) 642 (A12) DOI: 10.1051/0004-6361/201936214)

The erratum concerns Fig. 9 entitled "Antenna radio-electrical properties" for which some of the parameters are not correct. The new figure with new parameters is provided in Fig. 1 of this corrigendum. Fig. 1. Corrected Antenna radio-electrical properties. (Figure Presented)

Perceived Lightness/Darkness and Warmth/Coolness in Chromatic Experience

There are widespread beliefs that red, orange, and yellow are warm colors while blue, green, and purple are cool. In addition, some colors, like yellow, are said to be lighter than others, such as blue. The present study investigated how the psychological dimensions of hue, saturation and lightness contribute to these distinctions, and attempted to relate ratings of these attributes to the Opponent Process Theory. Subjects rated colored chips from the Natural Color System atlas for their warmth/coolness or lightness/darkness. Increases in the percentage of saturation in a color produced warmer ratings with the specific amount of increase depending on the hue. Changes in lightness did not significantly affect warmth/coolness ratings. Increases in saturation and in blackness both produced darker ratings, but the size of the increase in ratings depended on the hue. In addition, hues associated with longer wavelengths were rated as warmer than those associated with shorter wavelengths, while hue had no significant effects on ratings of lightness/darkness. Furthermore, higher ratings of warmth were found to correspond with opponent channel activation in one direction, while lower ratings corresponded with activation in the opposite direction. This suggests that warmth ratings may be associated with the low-level physiological processes involved in color perception, rather than with the psychological dimension of hue, and that the attribution of thermal properties to colors may be more than simply a cognitive process

Role of calcium cycling versus restitution in the mechanism of repolarization alternans

T-wave alternans, a powerful marker of arrhythmic events, results from alternation in action potential duration (APD). The underlying cellular mechanism of APD alternans is unknown but has been attributed to either intracellular calcium (Ca2+) cycling or membrane ionic currents, manifested by a steep slope of cellular APD restitution. To address these mechanisms, high-resolution optical mapping techniques were used to measure action potentials and Ca2+ transients simultaneously from hundreds of epicardial sites in the guinea pig model of pacing-induced T-wave alternans (n=7). The pacing rates (ie, alternans threshold) at which T-wave (369+/-11 bpm), APD (369+/-21 bpm), and Ca2+ (371+/-29 bpm) alternans first appeared were comparable. Importantly, the site of origin of APD alternans and Ca2+ alternans consistently occurred together near the base of the left ventricle, not where APD restitution was steepest. In addition, APD and Ca2+ alternans were remarkably similar both spatially and temporally during discordant alternans. In conclusion, the mechanism underlying T-wave alternans in the intact heart is more closely associated with intracellular Ca2+ cycling rather than APD restitution

Criterios Clínicos para el Manejo de las Complicaciones del Tejido Blando Periimplantar

Fil: Seni, SL. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I; Argentina.Fil: Mollo, LN. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I; Argentina.Fil: Katra, R. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I; Argentina.Fil: Bugatto, AL. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I; Argentina.Fil: Puia, SA. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I; Argentina.Las complicaciones del tejido blando periimplantar condicionan la apariencia estética y el pronóstico clínico de los implantes y son, en la actualidad, cada vez más diagnosticadas. Los defectos gingivales aso-ciados a implantes dentales incluyen recesiones, fe-nestraciones o dehiscencias en la superficie mucosa vestibular, inflamación gingival, ausencia de encía insertada/queratinizada, falta de volumen y presen-cia de concavidades gingivales que generan sombras y oscuridad en la mucosa. La detección de éstas en forma temprana permite establecer un plan de tra-tamiento en busca de soluciones eficaces. Mediante la presentación de una serie de casos, abordaremos distintos procedimientos para aumento de los tejidos blandos periimplantarios y la corrección de defectos. La ganancia de encía queratinizada ha demostrado tener un impacto positivo en la estabilidad a largo pla-zo de todos los tejidos implantarios

Análisis de Factores Etiológicos : desencadenantes de alveolitis

Fil: Markiewicz, J. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.Fil: Bugatto, A. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.Fil: Mollo, L. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.Fil: Katra, R. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.Fil: Seni, S. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.Fil: Puia, S. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Ortodoncia; Argentina.La alveolitis dental se caracteriza por la aparición de dolor agudo que rodea al alvéolo postextracción, que aumenta de intensidad entre el primer y tercer día posterior a la cirugía, seguido por una pérdida parcial o total de coágulo, con o sin halitosis. Si bien su etiología se considera multifactorial, es muy controversial la responsabilidad que tienen los factores de riesgo en su desarrollo

Estudio del Miedo en Pacientes Frente a la Extracción del Tercer Molar

Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I. Buenos Aires, Argentina.Universidad de Buenos Aires. Facultad de Psicología. Maestría en Psicología Educacional. Buenos Aires, Argentina.Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I. Buenos Aires, Argentina.Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I. Buenos Aires, Argentina.Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Cirugía y Traumatología Bucomaxilofacial I. Buenos Aires, Argentina