Coral Disease and Health Workshop: Coral Histopathology II

The health and continued existence of coral reef ecosystems are threatened by an increasing array of environmental and anthropogenic impacts. Coral disease is one of the prominent causes of increased mortality among reefs globally, particularly in the Caribbean. Although over 40 different coral diseases and syndromes have been reported worldwide, only a few etiological agents have been confirmed; most pathogens remain unknown and the dynamics of disease transmission, pathogenicity and mortality are not understood. Causal relationships have been documented for only a few of the coral diseases, while new syndromes continue to emerge. Extensive field observations by coral biologists have provided substantial documentation of a plethora of new pathologies, but our understanding, however, has been limited to descriptions of gross lesions with names reflecting these observations (e.g., black band, white band, dark spot). To determine etiology, we must equip coral diseases scientists with basic biomedical knowledge and specialized training in areas such as histology, cell biology and pathology. Only through combining descriptive science with mechanistic science and employing the synthesis epizootiology provides will we be able to gain insight into causation and become equipped to handle the pending crisis. One of the critical challenges faced by coral disease researchers is to establish a framework to systematically study coral pathologies drawing from the field of diagnostic medicine and pathology and using generally accepted nomenclature. This process began in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a working group organized under the auspices of the U.S. Coral Reef Task Force, and the International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and was focused on gross morphology and disease signs observed in the field. A resounding recommendation from the histopathologists participating in the workshop was the urgent need to develop diagnostic criteria that are suitable to move from gross observations to morphological diagnoses based on evaluation of microscopic anatomy. (PDF contains 92 pages

Reactive transport modelling of a high-pH infiltration test in concrete

A laboratory-scale tracer test was carried out to characterize the transport properties of concrete from the Radioactive Waste Disposal Facility at El Cabril (Spain). A hyperalkaline solution (K-Ca-OH, pH = 13.2) was injected into a concrete sample under a high entry pressure in order to perform the experiment within a reasonable time span, obtaining a decrease of permeability by a factor of 1000. The concentrations of the tracers, major elements (Ca2+, SO42-, K+ and Na+) and pH were measured at the outlet of the concrete sample. A reactive transport model was built based on a double porosity conceptual model, which considers diffusion between a mobile zone, where water can flow, and an immobile zone without any advective transport. The numerical model assumed that all reactions took place in the immobile zone. The cement paste consists of C-S-H gel, portlandite, ettringite, calcite and gypsum, together with residual alite and belite. Two different models were compared, one with portlandite in equilibrium (high initial surface area) and another one with portlandite reaction controlled by kinetics (low initial surface area). Overall the results show dissolution of alite, belite, gypsum, quartz, C-S-H gel and ettringite and precipitation of portlandite and calcite. Permeability could have decreased due to mineral precipitation.Peer ReviewedPostprint (author's final draft

The Basalt of Patagonia

The samples subjected to the microscopic examination and chemical analysis were provided by the 4th Scientific Expedition to Patagonia by Hiroshima & Hokkaido Univ., 1969. The party collected them on the continental side of the southern Andes between Mendoza and Santa Cruz in Argentina. The present writers tried in the first place to clarify the order of eruption, in the second place to define the petrological and chemical properties of the basalts, and at last some genetic considerations were pursued

Analytical Model Determining the Optimal Block Size in the Block Caving Mining Method

Nowadays along with population growth, industry development, consumption of mineral resources and the fact that the reserves on hand are running out, the depth of surface and underground mines for further exploitation are increasing. During recent years, in underground mining, the block caving method for low-grade and large-scale deposits has shown a growing rate of application. The dimensions of blocks are one of the most important parameters which should be taken into account since it has been proved to have a great deal of effect on technical issues such as commencement of caving and mine design. In this study, some assumptions were considered and having used these assumptions for estimation of optimized length and width of block, a relationship was explored. And finally, it was transformed into an inequality. Solving this inequality provides us with the optimized length and width of the block. The explored relationship was analysed using MATLAB and the resulting graphs thereof were drawn. Simulation was carried out using the Phase2 software and the results were compared with the different modes of the block. In the blocks that were 55, 60 and 65m in length, the total displacement (the total displacement as a result of applying force in order to cave), yielded elements (percent) and Yielded Joints reached a satisfactory condition which enables perfect caving to occur. In addition, in the 70m block, these values reached their maximum. It was concluded in this paper that the optimal block size is between 55 and 65m

Paleocene Cyclic Sedimentation in the Western North Atlantic, ODP Site 1051, Blake Nose

Upper Paleocene (zone CP8b) cyclic sediment from Ocean Drilling Program (ODP) Site 1051 on Blake Nose, western North Atlantic, alternates from white carbonate-rich to green carbonate-poor in response to precessional forcing. Compositional differences between the two bed types are minor: mineral and nannofossil composition of the beds vary subtly, but grain size of the terrigenous component and biogenic silica content remain constant. Iron content determined by sediment magnetic susceptibility and iron intensity determined by a core-scanning XRF correlates negatively with carbonate content and are higher in green beds. Kaolinite content of green beds is slightly higher as well. Green beds exhibit lower evenness values than white beds for nannofossil assemblages and are more dominated by the species Coccolithus. Dominance by Coccolithus indicates more mesotrophic conditions over Blake Nose during deposition of the green beds, which correlates with slightly higher iron and kaolinite contents. The absence of change in terrigenous grain size and the absence of any indication of planktonic blooms indicate that there was a minor, most likely eolian, input of iron and kaolinite during deposition of the green beds. The source area was most likely northwest Africa, which supplied iron and kaolinite when source areas deflated under drier conditions. With this scenario, kaolinite is an indicator of drier climate and source area erosion, rather than the warmer and/or wetter conditions under which it forms in soils. During precessional minima or perihelion summer (the opposite of our current configuration), there was an increased range of seasonal temperatures and an increase in the intensity of summer and winter monsoon circulation. As a consequence, there was more rainfall in northern Africa and drier conditions in the continental interiors at mid-latitudes. Green bed deposition occurred during precessional maxima when the North Atlantic was cooler, northwest Africa drier, and the eolian flux to the western North Atlantic slightly increased