Glyceraldehyde‐3‐phosphate dehydrogenase from spinach chloroplasts has been crystallized by vapour diffusion in the pH range 7–8.5 in (NH4)2SO4 and Tris–HCl buffer or potassium phosphate buffer at ...room temperature. Crystals of the A4 isoform, grown at pH 8.5 in Tris–HCl buffer, diffract to 3.0 Å (at 100 K) using synchrotron radiation. The crystals belong to the orthorhombic C222 space group, with unit‐cell dimensions a = 145.9, b = 185.9 and c = 106.3 Å, and probably contain one tetramer per asymmetric unit. Structure determination by molecular replacement is in progress.
The divertor assembly for the ITER fusion reactor consists of a number of rail mounted cassettes (54 now in ITER FEAT) located in the bottom region of the vacuum vessel. These cassettes shall be ...removed/installed remotely during the life of the reactor by means of specific devices. To demonstrate and optimise the feasibility of the in-vessel maintenance process the Divertor Test Platform (DTP) has been established at the ENEA Research Centre in Brasimone, Italy, as a major part of the large ITER R&D project L7. A first set of tests has been already carried out and reported during 1998, when the basic feasibility of the divertor replacement was demonstrated. In the present period (January 1999–July 2000), new activities, including both site tests and other “external” R&D works, have been carried out in order to refine and improve the ITER divertor maintenance scenario. These include the study of abnormal maintenance operations and of possible handling equipment failure and its consequences; the procurement and testing of new sub-systems (e.g. a force reflection manipulator arm), and the development of remote handling techniques including a virtual reality system. Following a short description of the DTP, this paper reports on the new results and achievements, draws the relevant conclusions, and finally discusses future activities.
Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new ...frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact.
Spatial decoherence near metallic surfaces Fermani, R.; Scheel, S.; Knight, P. L.
Physical review. A, Atomic, molecular, and optical physics,
03/2006, Letnik:
73, Številka:
3
Journal Article
We present a first-principles derivation of spatial atomic-sublevel decoherence near dielectric and metallic surfaces. The theory is based on the electromagnetic-field quantization in absorbing ...dielectric media. We derive an expression for the time variation of the off-diagonal matrix element of the atomic density matrix for arbitrarily shaped substrates. For planar multilayered substrates we find that for small lateral separations of the atom's possible positions the spatial coherence decreases quadratically with the separation and inversely to the squared atom-surface distance.
The ITER divertor assembly consists in 60 cassettes located in the bottom region of the vacuum vessel. Because of erosion and damage, their replacement is expected to be required eight times during ...the machine lifetime. The cassettes will be remotely withdrawn from the vessel through dedicated ducts and they will be transported to a hot cell for refurbishment. To demonstrate the feasibility of the withdrawal operations, and to optimise the maintenance scenario and the handling equipment design, a test facility has been set-up at the ENEA Research Centre of Brasimone (Italy), i.e. the divertor test platform (DTP) that allows to simulate, in full scale, all handling operations inside the vacuum vessel. This paper describes the objectives, test programme, layout, test results and future activities of the DTP.
Phys. Rev. A 73, 032902 (2006) (9 pages) We present a first-principles derivation of spatial atomic-sublevel
decoherence near dielectric and metallic surfaces. The theory is based on the
...electromagnetic-field quantization in absorbing dielectric media. We derive an
expression for the time-variation of the off-diagonal matrix element of the
atomic density matrix for arbitrarily shaped substrates. For planar
multilayered substrates we find that for small lateral separations of the
atom's possible positions the spatial coherence decreases quadratically with
the separation and inversely to the squared atom-surface distance.
We present a first-principles derivation of spatial atomic-sublevel decoherence near dielectric and metallic surfaces. The theory is based on the electromagnetic-field quantization in absorbing ...dielectric media. We derive an expression for the time-variation of the off-diagonal matrix element of the atomic density matrix for arbitrarily shaped substrates. For planar multilayered substrates we find that for small lateral separations of the atom's possible positions the spatial coherence decreases quadratically with the separation and inversely to the squared atom-surface distance.
Se investigó la variación en la distribución espacial y temporal de las características del tamaño de grano de los sedimentos superficiales y se identificaron áreas susceptibles a contaminación ...asociadas al tamaño de grano fino en Bahía Cullera, España. Se analizaron 90 muestras de sedimento superficial que fueron recolectadas durante seis campañas de muestreo a mediados y finales de verano y mediados de otoño de 2002, y a mediados de invierno, primavera y verano de 2003. Se analizó el tamaño de grano aplicando diferentes métodos como el análisis bivariante y funciones discriminantes empleadas en la interpretación de mecanismos y ambientes de depositación. Para identificar las zonas con mayor susceptibilidad de ser contaminadas por substancias tóxicas asociadas a tamaños de grano fino, se obtuvieron mapas de contornos de la distribución del tamaño medio de grano para las seis campañas de muestreo. Los sedimentos superficiales de Bahía Cullera se diferenciaron de acuerdo al escenario de depositación en depósitos de sedimentos marinos someros y depósitos de sedimentos fluviales asociados a la descarga del Río Júcar. La variación espaciotemporal mostró que la concentración de sedimentos gruesos se presentó en la región más cercana a la desembocadura del río, mientras que los sedimentos más finos se concentraron en la zona central y norte de la bahía durante la época de escasez de lluvia, por lo que durante esta época los sedimentos superficiales de estas zonas podrían ser susceptibles de contaminación por substancias nocivas asociadas a tamaños de grano fino.
Localizada en el Mediterráneo español, la Bahía de Cullera está influenciada por las descargas del Río Júcar y por un emisor submarino que descarga sus aguas residuales justo en la desembocadura del ...río. En el marco del proyecto ECOSUD se llevaron a cabo cinco campañas de muestreo entre julio de 2002 y abril de 2003, en 11 estaciones distribuidas a lo largo de la costa y en el emisor submarino, para determinar la distribución espaciotemporal de la calidad bacteriológica (coliformes fecales, Escherichia coli y enterococos) del agua de mar con la finalidad de detectar posibles áreas peligrosas para usos recreativos y de baño de las playas de la bahía, según los estándares determinados por la Comisión Ambiental Europea. Los resultados obtenidos muestran que, en general, la zona costera de Bahía Cullera mantiene una buena calidad en sus aguas de baño. Sin embargo, la influencia de las descargas tanto del emisario submarino como del Río Júcar tiene un impacto en la zona costera, donde el aumento de la concentración bacteriológica disminuye la calidad de las aguas, sobretodo en los meses de verano cuando la actividad turística es intensa. El aporte adicional de fuentes esporádicas de contaminación en la zona del Cabo Cullera ocasiona un incremento por encima del valor máximo permisible de concentración de bacterias (2000 UFC 100 mL-1 para coliformes fecales, 200 UFC 100 mL-1 para enterococos y 500 UFC 100 mL-1 para E. coli). Además, tomando en cuenta que el patrón de corrientes está controlado por el régimen estacional de los vientos, la zona norte podría llegar a ser una futura fuente adicional de bacterias contaminantes a las zonas de la playa, que hasta hoy mantienen una buena calidad de agua.
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