Use of the geostrophic approximation to estimate time-varying zonal currents at the Equator

Moored thermistor chains at 2°N and 2°S and current-temperature moorings at 0° are used to examine the accuracy of geostrophically estimated zonal velocity on the equator in the eastern (110°W) and werstern (165°E) Pacific. The meridionally differentiated form of the geostrophic balance is used to eliminate large errors due to wind-balanced cross-equatorial pressure gradients. Statistical analyses indicate that for time scales longer then 30-50 days, the observed and geostrophically estimated zonal velocities are similar (correlation coefficients of O.6-0.9 and comparable amplitudes). Thus low-frequency equatorial current oscillations are reasonably well represented by the geostrophic approximation. However, the mean currents are poorly resolved with the available array. In the eastern Pacific the mean zonal speed difference over the 10 month comparison period is 25 cm s-1 at 25 m and increases to 60 cm s-1 at 125 m. At 165°E mean differences in the upper 250 m are tipically 50 cm s-1 over a 4-month record

The response of the Western Equatorial Pacific ocean to Westerly wind bursts during november 1989 to january 1990

Several 5 to 10 m s-1 westerly wind bursts of 10-15 days' duration occurred in the Western Equatorial Pacific during november 1989 to January 1990. The response to these wind bursts was characterized by a 400- to 600 km wide eastward jet in the upper 100-150 m along the equator between 135°E and the date line. Flow in this jet accelarated to speeds of over 100 cm s-1 within 1 week after the onset of westerly winds in november 1989 in association with super thyphoon Irma. In addition, a 20 to 40 cm s-1 westward counterflow developed between 2°N and 2°S below the surface jet separating it from the eastward flow of the Equatorial undercurrent in the thermocline. Changes in surface layer zonal volume transport in the Western Pacific due to westerly wind bursts were 25-56 Sv based on comparison of three shipboard velocity transects in november and december 1989. Although fluctuations in current speeds in the thermocline were generally smaller and less directly related to local wind forcing than those in the surface layer, the Equatorial undercurrent decelerated to less than 20 cm s-1 (i.e., less than half its speed before the onset of westerlies) by early december 1989. (D'après résumé d'auteur

Amélioration des systèmes d'observations pour la surveillance en temps réel de la structure thermique du Pacifique tropical

Grâce à l'aide du MRES, le groupe de recherche d'océanographie physique SURTROPAC, du Centre ORSTOM de Nouméa-Nouvelle-Calédonie a pu s'impliquer à fond dans une coopération internationale de mise en place et d'analyse des données issues d'un nouveau réseau de mesures dans le Pacifique. Ce réseau est constitué d'un ensemble de bouées, mouillées par grand fond, et équipées de chaîne à thermistance, de capteur de vent et d'un transmetteur de données ARGOS. Il permet de suivre en temps quasi réel la variabilité des vents de surface et de la structure thermique des couches de sub-surface de l'Océan Pacifique Equatorial et d'en comprendre les mécanismes. Parallèlement il a été testé un nouveau système de transmission de données bathythermographiques par satellite sur deux navires marchands que le groupe SURTROPAC utilise pour assurer la couverture de l'état thermique du Pacifique Tropical. Ces deux études font partie intégrante du grand programme international TOGA (Tropical Ocean and Global Atmosphere) de dix années qui a pour but essentiel la compréhension et la prédiction des fluctuations interannuelles du climat de notre planète. (Résumé d'auteur

Organic Pollutants, Heavy Metals and Toxicity in Oil Spill impacted Salt Marsh Sediment Cores, Staten Island, New York City, USA

Sediment cores from Staten Island's salt marsh contain multiple historical oil spill events that impact ecological health. Microtox solid phase bioassay indicated moderate to high toxicity. Multiple spikes of TPH (6524 to 9586 mg/kg) and Σ16 PAH (15.5 to 18.9 mg/kg) were co-incident with known oil spills. A high TPH background of 400–700 mg/kg was attributed to diffuse sources. Depth-profiled metals Cu (1243 mg/kg), Zn (1814 mg/kg), Pb (1140 mg/kg), Ni (109 mg/kg), Hg (7 mg/kg), Cd 15 (mg/kg) exceeded sediment quality guidelines confirming adverse biological effects. Changes in Pb206/207 suggested three metal contaminant sources and diatom assemblages responded to two contamination events. Organic and metal contamination in Saw Mill Creek Marsh may harm sensitive biota, we recommend caution in the management of the 20–50 cm sediment interval because disturbance could lead to remobilisation of pre-existing legacy contamination into the waterway

Cryo-electron tomography of biological specimens

Cryo-electron tomography (CET) is an imaging technique capable of visualizing the three-dimensional (3-D) structure of complex viruses, cells, and tissues in hydrated state. With the current resolution of 4-5 nm, CET can resolve supramolecular complexes that are responsible for many cellular functions. This paper discusses the important considerations in CET of biological specimens and identify areas where digital signal processing can make a decisive contribution. Topics discussed include the principles of electron tomography and CET, image background and feature contrasts in CET, acquisition and alignment of projection images, reconstruction of the image volume, denoising and segmentation of tomograms, and feature recognition in cellular tomograms

The effects of trauma on intimate relationships: A qualitative study with clinical couples

Research has traditionally focused on the development of symptoms in those who experienced trauma directly but has overlooked the impact of trauma on victims' families. In recent years, researchers and clinicians have begun to examine how individual exposure to traumatic events affects the spouses or partners, children, and professional helpers of trauma survivors. The current study examines qualitative interview data from 17 individuals, analyzed using a retroductive methodology to identify how intimate relationships are affected when there is a history of trauma exposure. The following primary themes were identified: increased communication, decreased communication, increased cohesion/connection, decreased cohesion/connection, increased understanding, decreased understanding, sexual intimacy problems, symptoms of relationship distress, support from partner, and relationship resources. Areas for future research and clinical implications are identified

Failing boys and moral panics: perspectives on the underachievement debate

The paper re-examines the underachievement debate from the perspective of the ‘discourse of derision’ that surrounds much writing in this area. It considers the contradictions and inconsistencies which underpin much of the discourse – from a reinterpretation of examination scores, to the conflation of the concepts of ‘under’ and ‘low’ achievement and finally to the lack of consensus on a means of defining and measuring the term underachievement. In doing so, this paper suggests a more innovative approach for understanding, re-evaluating and perhaps rejecting the notion of underachievement

Complementarity of information sent via different bases

We discuss quantitatively the complementarity of information transmitted by a quantum system prepared in a basis state in one out of several different mutually unbiased bases (MUBs). We obtain upper bounds on the information available to a receiver who has no knowledge of which MUB was chosen by the sender. These upper bounds imply a complementarity of information encoded via different MUBs and ultimately ensure the security in quantum key distribution protocols.Comment: 9 pages, references adde