A Unified Model for Black Hole X-Ray Binary Jets?

We have recently put forward a ‘unified’ semi-empirical model for the coupling between accretion and jet production in galactic black hole X-ray binaries. In this paper, we summarise this model and briefly discuss relevant considerations that have arisen since its publication.     

Impact evaluation on groundwater of the infiltration of an urban wastewater geopurification system placed over a detrital aquifer in a semiarid region (Spain)

Over a period of 4 years and 4 months, the geopurification installations at Dehesas de Guadix (Granada, Spain) were monitored to determine the impact on soil and groundwater of the controlled discharge of urban wastewater, and also to identify the best indicators of the entry of the recharged water into the aquifer. The installations are located in an area where the climate is Mediterranean sub-arid, with an average precipitation of less than 287 mm/year, and a rate of evapotranspiration that is almost three times greater. The system was controlled by determining the balance of majority nutrients and boron in the soil and in the groundwater, both at the points affected directly by the wastewater discharge and at others. The quantity of mass discharged was relatively large (COD 14,656 g/m², NO₃ 85 g/m², NO₂ 4 g/m², NH₄ 2,425 g/m², PO₄ 1,143 g/m², K 1,531 g/m², B 63 g/m²). It was observed that the elimination of nutrients within the soil (COD 97.5%, PO₄ 94.4%, K 59.17%, N _total 18.8%, B 12.69%) was very efficient except for the nitrogen, which nevertheless did not reach the groundwater, as it was eliminated at deep levels of the unsaturated zone. Only 12.69% of the boron was removed, and appreciable, increasing amounts of this element did reach the groundwater. Unexpectedly, none of the majority nutrients behaved as a reliable indicator of the impact on groundwater; despite this, the boron and the bicarbonate did clearly reflect the arrival of the recharged water, and are proposed as the best indicators.     

Bacterial killing by Mytilus hemocyte monolayers as a model for investigating the signaling pathways involved in mussel immune defence

The signaling pathways involved in mussel immune defence were investigated utilizing a model of killing of Escherichia coli by Mytilus galloprovincialis hemocytes in a co-culture setting. In particular, the role played by different mitogen activated protein kinases (MAPKs) and by the production of eicosanoids were investigated utilising specific cell permeant, pharmacological enzyme inhibitors. Hemocyte pretreatment with the p38 MAPK inhibitor SB203580 significantly reduced bacterial killing, whereas PD98059 (an inhibitor of ERK--extracellularly regulated kinase--MAPK activation) had no significant effect. Wortmannin also inhibited bacterial killing, indicating a crucial role for PI3-kinase activation in the immune response. Killing of E. coli was also reduced by inhibitors of both PLA2 and cyclooxygenase activities, indicating that eicosanoid production is involved in mediating the response to bacterial challenge. The results demonstrate that bacterial killing by mussel hemocytes is particularly sensitive to inhibitors of the key steps involved in the transduction of bacterial signals into the host cell. Moreover, these data indicate that the hemocyte bactericidal activity can be suitably utilized not only for identifying the signaling pathways involved in the response to bacterial infection, but also as a potential investigative-toxicology model to test drugs and contaminants for their effect on the overall mussel immune defence.     

Tectonics at the intersection of the East Pacific Rise with Tamayo Transform fault

During the Fall of 1979, a manned submersible program, utilizing DSRV ALVIN, was carried out at the intersection of the East Pacific Rise (EPR) with the Tamayo Transform boundary. A total of seven dives were completed in the vicinity of the EPR/Tamayo intersection depression and documented the geologic relationships that characterize the juxtaposition of these types of plate boundaries. The young volcanic terrain of the EPR axis can be traced into and across the Tamayo Transform valley but becomes buried by sedimentary talus that is being shed from sediment scarps along the unstable sediment slope that defines the north side of the intersection depression. Within 4 km of the transform boundary, the dominant trend (000°) of the fissures and faults that disrupt the rise-generated volcanics is markedly oblique to the regional direction of sea floor spreading (120°). Since no evidence was found to suggest that these structures accommodate significant amounts of strike-slip displacement, they are taken to reflect a distortion of the EPR extensional tectonic regime by a transform generated shear couple. The floor of the Tamayo Transform valley in this area is inundated by mass-wasted sediment, and the principal transform displacement zone is characterized at the surface by a narrow (<1.5 km) interval of fault scarps in sediment that trends parallel with the transform valley. Extrapolated to the west, this zone links with zones of transform deformation investigated during earlier submersible studies (CYAMEX and Pastouret, 1981). Evidence of low-level hydrothermal discharge was seen at one locality on the EPR axis and at another 8 km west of the axis at the edge of the zone of transform deformation.     

Monitoring the status of a mechanical cable while in operation by means of the acoustic emission method

The mechanical cable is an essential element in towing operations, remote control of equipment, salvage operations, civil engineering applications, etc.Failure of these cables can result in loss of life and loss of equipment worth hundreds of thousands of dollars. Obviously then, sensors that can indicate the condition of these cables so that the risk to their continued use and their remaining safe life can be determined when in operation are very important from the point of view of commercial and military interest.This paper presents a brief review of research into failure mechanisms of various cables and the acoustic emission signatures of the various cables under simulated loading. The development of a specific operational monitor for a towed cable system is also given.     

Nutrients and zooplankton composition and dynamics in relation to the hydrological pattern in a confined Mediterranean salt marsh (NE Iberian Peninsula)

The role of the hydrological regime in the nutrients and zooplankton composition and dynamics has been analysed in five lagoons of La Pletera salt marshes (NE Iberian Peninsula) during a complete hydrological cycle (2002–2003). Two of the lagoons have their origin in the old river mouths while the other three were recently created in the framework of a Life Restoration project. This fact has also allowed us to study the effect of the lagoon age on nutrient and zooplankton composition and dynamics. The salt marsh hydrology is determined by a prolonged period of confinement without water inputs, irregularly interrupted by sudden water inputs due to flooding events (sea storms or intense rainfalls). While the dynamics of oxidized nitrogen compounds in the lagoons depends on the water inputs variability within each hydrological cycle, the internal load of phosphorus, total nitrogen and organic matter is related more to the cumulative mechanisms during the confinement periods. Accumulation processes may be easily related to lagoon age, since old lagoons have higher content of nutrients and organic matter, suggesting that these lagoons progressively accumulate nutrients during the successive confinement events. This is the usual case for most Mediterranean salt marshes without an artificially manipulated water regime. The zooplankton community in La Pletera integrates the effects of both the hydrological regime and the lagoon age since the former determines the temporal pattern of the main zooplankton species and the latter explains differences in composition and structure between old and new lagoons.     

Interpretation of radon anomalies in seismotectonic and tectonic-gravitational settings: the south-eastern Crati graben (Northern Calabria, Italy)

The study area is located in the south-eastern part of the Crati valley (Northern Calabria, Italy), which is a graben bordered by N–S trending normal faults and crossed by NW–SE normal left-lateral faults. Numerous severe crustal earthquakes have affected the area in historical time. Present-day seismic activity is mainly related to the N–S faults located along the eastern border of the graben. In this area, much seismically induced deep-seated deformation has also been recognised.In the present paper, radon concentrations in soil gas have been measured and compared with (a) lithology, (b) Quaternary faults, (c) historical and instrumental seismicity, and (d) deep-seated deformation.The results highlight the following:

(a) There is no evidence of a strong correlation between lithology and the radon anomalies.

(b) A clear correlation between the N–S geometry of radon anomalies and the orientation of main fault systems has been recognised, except in the southernmost part of the area, where the radon concentrations are strongly affected by the superposition of the N–S and the NW–SE fault systems.

(c) Epicentral zones of instrumental and historical earthquakes correspond to the highest values of radon concentrations, probably indicating recent activated fault segments. In particular, high radon values occur in the zones struck by earthquakes in 1835, 1854, and 1870.

(d) Deep-seated gravitational deformation generally coincides with zones characterised by low radon concentrations.

In the studied area, the anisotropic distribution of radon concentrations is congruent with the presence of neotectonic features and deep-seated gravitational phenomena. The method used in this study could profitably contribute towards either seismic risk or deep-seated gravitational deformation analyses.     

Denitrification rates measured along a salinity gradient in the eutrophic Neuse River estuary, North Carolina, USA

Denitrification rates along a salinity gradient in the eutrophic Neuse River Estuary, North Carolina, were quantified using membrane inlet mass spectrometry (MIMS) within short-term batch incubations. Denitrification rates within the system were highly variable, ranging from 0 to 275 μmol N m⁻² h⁻¹. Intrasite variability increased with salinity, but no significant differences were observed across the salinity gradient. Denitrification rates were positively correlated with sediment oxygen demand at the upstream sampling site where sediment organic carbon levels were lowest. This relationship was not observed in the more saline sampling sites. Denitrification rates were highest during winter. On an annual basis, denitrification accounted for 26% of the dissolved inorganic nitrogen and 12% of the total nitrogen supplied to the system.