Effect of the beam-vessel angle on the received acoustic signalfrom blood

In order to explore the feasibility of algorithms to determine the three dimensional (3D) velocity magnitude from the received ultrasonic blood echo from a single line of sight, the signal from small sample volumes is studied as a function of beam-vessel angle. As opposed to previous treatments of the effect of the beam-vessel angle on the received acoustic signal, a wideband signal is transmitted and the returned signal in each sample volume is analyzed. High-resolution experimental M-mode images of radio-frequency (rf) echo signals are used to visualize the flow in individual regions of interest. These experiments confirm the predictions of a theoretical model for the signal and its second moment. It is shown that the two major effects limiting the correlated signal interval are the spread of axial velocities within the sample volume and the transit time across the lateral beam width. Particularly for small beam-vessel angles, the spread of velocities limits the correlated signal interval. In addition, the experimental results demonstrate that accurate velocity estimation for low volume flow rates and particularly for large beam-vessel angles may involve detection of changes in the correlation magnitude. For low volume flow rates, the shape of the correlation surface can be affected by small regions of blood with a strong scattering intensity located near the initial region of interest     

Smoke dilution methods for the evaluation of the smoke emission from burning polymers: A comparative approach

A comparative approach to the determination of smoke emission from burning polymers has been attempted, and a number of combustion conditions and detection devices have been tried to choose a test method for measuring the smoke proiduction of materials. The combustion apparatus adopted is a hot-air quartz furnace that permits the measured by dynamic method from combustion of PAN, PVC and PVC mixed with some metal oxiders, have been compared with those obtained by an accumulation mode. For PVC the intensity of the light scattered from the evolving smoke has been measured as an alternative to smoke density.     

Linear mixture model applied to Amazonian vegetation classification

Many research projects require accurate delineation of different secondary succession (SS) stages over large regions/subregions of the Amazon basin. However, the complexity of vegetation stand structure, abundant vegetation species, and the smooth transition between different SS stages make vegetation classification difficult when using traditional approaches such as the maximum likelihood classifier (MLC). Most of the time, classification distinguishes only between forest/non-forest. It has been difficult to accurately distinguish stages of SS. In this paper, a linear mixture model (LMM) approach is applied to classify successional and mature forests using Thematic Mapper (TM) imagery in the Rondônia region of the Brazilian Amazon. Three endmembers (i.e., shade, soil, and green vegetation or GV) were identified based on the image itself and a constrained least-squares solution was used to unmix the image. This study indicates that the LMM approach is a promising method for distinguishing successional and mature forests in the Amazon basin using TM data. It improved vegetation classification accuracy over that of the MLC. Initial, intermediate, and advanced successional and mature forests were classified with overall accuracy of 78.2% using a threshold method on the ratio of shade to GV fractions, a 7.4% increase over the MLC. The GV and shade fractions are sensitive to the change of vegetation stand structures and better capture biophysical structure information.     

A study on posidonia residue in seawater intakes

The reliability of a sea-water desalination plant relies largely on an efficient intake system. This is not easily ensured in large areas of the Mediterranean, where the residue of a particular seagrass, Posidonia 0ceanica, is often found in large quantities. To separate or avoid this residue, which can cause operational problems, considerable technical and economical efforts are required.

This paper presents the results of a design and operation-oriented experimental study on Posidonia. This study deals with aspects such as concentration in sea-water, distribution of sizes in residue samples, sedimentation properties, bulk densities and resistance of sea-grass cakes to sea-water flow, and is supported by direct practice in desalination in Libya. Experience confirms that the analysis of the behaviour and physical properties of Posidonia residue, together with accurate site survey, enable one to design a tailored solution, thus avoiding an unreliable standardized system or an uneconomical sophisticated or over-dimensioned solution, not necessarily reliable when unassisted by field data.     

Secondary changes in the chemical and isotopic composition of the geothermal fluids in Larderello field

Processes such as condensation of rising steam in colder horizons, mixing of deep steam with shallower waters and non-geothermal gas inflow are known to exist in the vapour-dominated geothermal system of Larderello. Deep steam drawn up by geothermal wells modifies its original chemico-physical characteristics in relation to the presence of one or more ‘secondary’ phenomena occurring in each point of the field. ¹³C/¹²C ratios in CO₂ and CH₄, chloride-ammonia-boric acid contents, H₂/H₂S and gas/steam ratios are used as useful parameters in delimiting the different zones in which this kind of phenomena predominate. Six main areas seem to be characterized geochemically, showing marked variations that are essentially due to differences in the geohydrological situations and thermal conditions.     

CO2 distribution in the atmosphere and noise survey after blow-out in alfina 1 well, Northern Latium, Italy

A water-dominated geothermal reservoir, with a gas cap (mainly CO₂) on the reservoir roof, was individualed in Torre Alfina zone, northern Latium, about 30 km south-east of Monte Amiata.The first exploratory well (Alfina 1), drilled in 1973, blew-out spontaneously so that no production casing could be inserted.After well shut-in several surface gas manifestations appeared which were considered of some risk to the environment.This paper describes the methods used to determine the degree of pollution and the total area involved.The study of the gas dispersion in the atmosphere, the noise resulting from production, and the meteorological conditions in the area, was used in drawing up a disposal plant project; this plant will be assembled on future wells as a safety measure where large quantities of fluids are involved.     

Total body irradiation and acute graft-versus-host disease: the role of gastrointestinal damage and inflammatory cytokines

The influence of bone marrow transplantation (BMT) conditioning regimens on the incidence and severity of graft-versus-host disease (GVHD) has been suggested in clinical BMT. Using murine BMT models, we show here an increase in GVHD severity in several donor-recipient strain combinations after intensification of the conditioning regimen by increasing the total body irradiation (TBI) dose from 900 cGy to 1,300 cGy. Increased GVHD was mediated by systemic increases in tumor necrosis factor alpha (TNF alpha). Histologic analysis of gastrointestinal tracts showed synergistic damage by increased TBI and allogeneic donor cells that permitted increased translocation of lipopolysacharide (LPS) into the systemic circulation. In vitro, LPS triggered excess TNF alpha from macrophages primed by the GVH reaction. In addition, macrophages isolated within 4 hours of conditioning were primed in proportion to the TBI dose itself to secrete TNF alpha. Thus, the higher TBI dose increased macrophage priming and increased gut damage after allogeneic BMT, causing higher systemic levels of inflammatory cytokines and subsequent severe GVHD. These data highlight the importance of conditioning in GVHD pathophysiology and suggest that interventions to prevent LPS stimulation of primed macrophages may limit the severity of GVHD after intensive conditioning for allogeneic BMT.     

Preparation of High - Purity Tl(1223) Ceramics

The influence of changes in the nominal composition and preparation conditions on the formation of Tl(1223) under a high isostatic gas pressure was studied. Optimization of the cation substitution allowed to increase the phase purity, whereas substitution of small amounts of oxygen by fluorine decreased the formation temperature of the Tl(1223) phase and extended the temperature range favorable for grain growth. A two-step reaction involving substantial melting produced well shaped, plate-like grains.     

Methods to Produce Tl(1223) Tapes with Improved Properties

Different methods to prepare superconducting mono- and multifilamentary T1(I223) tapes were developed. High-purity ceramics could be produced by ex-situ or in-situ reaction under a high isostatic gas pressure. Tapes prepared by the PIT method and an in-situ reaction carried out close to the melting point of the oxide were relatively dense and textured. Interesting results were obtained for samples where part of the oxygen atoms in Tl(1223) had been substituted by fluorine. Critical current densities up to 20'000 A/cm² (77 K, 0 T) were reached for tapes produced by the PIT method. Well textured samples were obtained by electrophoretic deposition, the deposited Tl(1223) grains being produced by a synthesis involving substantial melting.