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Volume Determination (volume + determination)
Selected AbstractsVolume determination for bulk materials in bunkersINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2004S. A. Ahmed Abstract A simple model for the determination of the shape of large granular piles in complicated geometries is discussed. An eikonal formulation of the problem is proposed. Two distinct cases arise. In cylindrical geometries, i.e., if both container and possible obstacles have vertical walls, the problem is equivalent to a two-dimensional travel time problem with obstacles, while in general geometries, this analogy breaks down. In the first case, classical one-sided discretizations are generalized to handle obstacles without loss in accuracy. In the second case, a fast and efficient numerical method is proposed, implemented and tested. The discrete problems are solved through fast marching. Copyright © 2004 John Wiley & Sons, Ltd. [source] Fluid Volumes Determination by Impedance Spectroscopy and Hematocrit Monitoring: Application to Pediatric HemodialysisARTIFICIAL ORGANS, Issue 2 2001Marianne Fenech Abstract: A method for extracting fluid volumes from multifrequency bioimpedance, which takes into account the body geometry and the presence of nonconducting elements, was tested on 12 young dialyzed patients against correlations for total body water volumes (TBW) from Watson et al. and Humes et al. Our calculations of TBW from impedance were found to overestimate Humes' values by 0.25 L (0.8%) postdialysis and by 2.08 L (6.5%) predialysis. Extracellular water (ECW) was found to contribute an average of 93% of ultrafiltered volume. Intracellular water volume (ICW) determination from impedance was found to be too imprecise to predict its variation during dialysis; therefore, ICW variations were calculated as the difference between ultrafiltration and ECW changes. The continuous recording of hematocrit by an optical device monitored changes in plasma and interstitial volumes. In most cases, ultrafiltration was compensated mainly by a contribution from interstitial fluid, and the drop in plasma volume was generally moderate. [source] The urban market for farmers' water rights,IRRIGATION AND DRAINAGE, Issue 4 2003Stephen Merrett stress de répartition; irrigation; droits à l'eau; provision urbaine Abstract Allocation stress, that is, access conflicts between the agricultural, domestic, industrial, urban service and environmental uses of water, is set to become more intense in the future because of global population growth and climate change. Because of the dominant role of irrigation water use at the global level, it is imperative to explore the possibilities of reducing farmers' use of water or, at the very least, of slowing its growth. One process by which the scale of irrigation is reduced occurs when farmers choose to sell their water rights to actors that apply these released flows in towns and cities for household, manufacturing and urban service uses. In this paper a theory of price and volume determination of such markets is presented, using concepts of urban actors' maximum bid price and farmers' minimum release price for water rights. The limits of the theory are then discussed with respect to timescale, water concessions, part-sales, sales of land, the legal context, third-party effects, market structure and transaction costs. The main conclusion is that the market equilibrium approach is rarely applicable and that fieldwork will in general have to deal with arcane, one-off bilateral trades. Copyright © 2003 John Wiley & Sons, Ltd. Les contraintes d'allocation de l'eau, c'est-a-dire, les conflits d'accès à l'eau entre secteurs agricole, domestique, industriel, urbain et de l'environnment, vont augmenter dans le futur, à cause du changement du climat et de la croissance de la population mondiale. Le rôle dominant de l'irrigation tend de réduire l'usage de l'eau dans la secteur agricole. Cette réduction se produit quand les fermiers vendent leur droits à l'eau aux acteurs urbains. Dans cet article on présente une théorie des prix et quantités de ces marchés. On présente aussi les limites de la théorie et on conclut que l'approche par équilibre du marché s'applique rarement et qu'il faut en pratique considerer egalement des transactions obscures et bilatérals. Copyright © 2003 John Wiley & Sons, Ltd. [source] Eignung eines großen Flüssigkeits- und eines Luftpyknometers zur Bestimmung des Rohvolumens von Feststoffen unterschiedlicher Art und GrößeJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2005Berthold Deller Abstract Das Feststoffvolumen von Materialien, die sowohl relativ große als auch spezifisch leichte Bestandteile enthalten, kann nach DIN ISO 11508 (mit relativ kleinen Flüssigkeitspyknometern (FP) und submerser Wägung in Wasser) nicht bestimmt werden. Deshalb wurde geprüft, ob es ohne Zerkleinerung des Untersuchungsmaterials in einem größeren FP (ca. 280,cm3) oder einem Luftpyknometer (LP) genau genug zu ermitteln ist. Materialien mit gröberen Bestandteilen bzw. Feststoffe mit sehr unterschiedlicher Rohdichte ergaben mit dem FP größere Differenzen zwischen Parallelansätzen als die wiederholte Befüllung mit Wasser und die Untersuchung von feinkörnigen Mineralböden erwarten ließ. Die wesentliche Ursache dafür wird in der materialspezifischen Inhomogenität gesehen. Das FP scheint somit für die Untersuchung von Materialien mit Partikeldurchmessern von bis zu 3,cm grundsätzlich geeignet. Die Bestimmung muss jedoch jeweils an mindestens zwei Parallelproben erfolgen und ggf. erweitert werden, um verlässliche Mittelwerte zu erhalten. Die gleiche Bestimmung mit einem selbst gebauten LP ergab zu niedrige Werte für das Rohvolumen, wenn die Materialien ofentrocken, lufttrocken und feucht waren (Ausnahme: solche mit kompakten und relativ großen Partikeln). Die Fehler traten sowohl bei der Messung durch Luftdrucksenkung (ca. ,300 hPa) als auch unter Druckerhöhung (ca. 100,hPa) auf. Das Volumen von reinem Wasser konnte demgegenüber unter Druckerhöhung wesentlich genauer und richtiger bestimmt werden. Nach Kochen der Proben (wie für die Flüssigkeitspyknometrie) und Überdecken mit Wasser in der LP-Messkammer waren die Ergebnisse deutlich besser mit denen des FP vergleichbar und plausibler. Die Fehlerursachen werden darin gesehen, dass die Messung durch adsorbierte Luft (getrocknete und lufttrockene Proben) gestört wird bzw. Wasser von den Materialoberflächen während des Messvorganges verdampft. Suitability of a large liquid pycnometer and an air pycnometer to determine the raw volume of solids of different type and size The raw volume of materials, which contain constituents of relatively large size as well as of low density, can not be determined according to ISO 11508 without grinding. Therefore, this study should show if the analysis can be performed on original-sized materials with a large liquid pycnometer (LP, volume of about 280,cm3) or a self-made air pycnometer (AP). When materials of particle size up to 16,mm and/or of very different raw density were analyzed with the LP, the differences between parallel measurements were considerably greater than those of fine-textured soils and than those expected from repeated filling of the LP with water. They are ascribed mainly to the inhomogeneity of the samples and less to measuring errors. Consequently, the LP used seems to be suitable for the determination of particles with constituent size of up to 3,cm. However, the volume determination of every sample has to be performed at least twice. If the results do not meet the required precision, more repetitious measurements have to be performed, or the sample amount has to be enlarged. The same determination with the AP led to comparable and plausible results only in the case of water and of materials with compact constituents of relatively great size mainly (sand and fine gravel), when the samples were oven-dry, air-dry, or fairly moist. The results of the other materials were comparable, when the same sample preparation was performed as with liquid pycnometry (heating-up in water) and when they were covered by water in the measuring cell during measurement. The deviations from LP measurements were reduced, when measuring was performed by increasing air-pressure conditions (100 hPa) instead of lowering (,300 hPa), but to an insufficient degree. The reason for erroneous results was attributed to the existence of adsorbed air on particle surfaces (dry materials) and the evaporation of water during the measuring step (moist samples), respectively. [source] High-throughput screening techniques for rapid PEG-based precipitation of IgG4 mAb from clarified cell culture supernatantBIOTECHNOLOGY PROGRESS, Issue 3 2010Carol Knevelman Abstract Locating optimal protein precipitation conditions for complex biological feed materials is problematic. This article describes the application of a series of high-throughput platforms for the rapid identification and selection of conditions for the precipitation of an IgG4 monoclonal antibody (mAb) from a complex feedstock using only microliter quantities of material. The approach uses 96-microwell filter plates combined with high-throughput analytical methods and a method for well volume determination for product quantification. The low material, time and resource requirements facilitated the use of a full factorial Design of Experiments (DoE) for the rapid investigation into how critical parameters impact the IgG4 precipitation. To aid the DoE, a set of preliminary range-finding studies were conducted first. Data collected through this approach describing Polyethylene Glycol (PEG) precipitation of the IgG4 as a function of mAb concentration, precipitant concentration, and pH are presented. Response surface diagrams were used to explore interactions between parameters and to inform selection of the most favorable conditions for maximum yield and purification. PEG concentrations required for maximum yield and purity were dependant on the IgG4 concentration; however, concentrations of 14 to 20% w/v, pH 6.5, gave optimal levels of yield and purity. Application of the high-throughput approach enabled 1,155 conditions to be examined with less than 1 g of material. The level of insights gained over such a short time frame is indicative of the power of microwell experimentation in allowing the rapid identification of appropriate processing conditions for key bioprocess operations. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Longitudinal pulmonary status of cystic fibrosis children with meconium ileusPEDIATRIC PULMONOLOGY, Issue 4 2004Zhanhai Li PhD Abstract Although meconium ileus (MI) is the earliest manifestation of cystic fibrosis (CF), and is associated with poorer growth, the longitudinal pulmonary progression of CF children with MI is not clear. To test the hypothesis that MI is associated with worse pulmonary outcomes, we prospectively compared from diagnosis to 12 years of age 32 CF children with MI to 50 CF children without MI who were diagnosed during early infancy through neonatal screening. Pulmonary outcome measures included respiratory symptoms, respiratory infections, pathogens, antibiotic usage, hospitalizations, quantitative chest radiology, spirometry, and lung volume determinations. Obstructive lung disease was defined as percent predicted spirometry values below the lower limits of normal. Longitudinal analyses revealed no significant differences in cough, wheezing, respiratory infections, prevalence of and median times to acquisition of Pseudomonas aeruginosa or Staphylococcus aureus, antibiotic usage, and chest radiograph scores between the two groups. However, MI children showed significantly worse forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), forced expiratory flow between 25,75% of FVC (FEF25,75), % predicted FEV1, % predicted FEF25,75, and total lung capacity (TLC). These differences were particularly apparent beginning at age 8,10 years. MI children also had higher rates of and shorter median times to obstructive lung disease. Subgroup analyses showed MI children treated surgically and those treated medically had similar pulmonary outcomes. In conclusion, MI children have worse lung function and more obstructive lung disease than those without MI. Such abnormalities are accompanied by reduced lung volume. MI is a distinct CF phenotype with more severe pulmonary dysfunction. Pediatr Pulmonol. 2004; 38:277,284. © 2004 Wiley-Liss, Inc. [source] Accurate calculation of the density of proteinsACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2000Michael L. Quillin On the basis of theoretical calculations, Andersson & Hovmöller have recently suggested that the long-established value of 1.35,g,cm,3 for the mean density of proteins should be revised to 1.22,g,cm,3[Andersson & Hovmller (2000), Acta Cryst. D56, 789790]. To substantiate their assertion, these authors used the Voronoi algorithm to calculate the mean atomic volume for 30 representative protein structures. The Voronoi procedure requires that atoms of interest be bounded on all sides by other atoms. Volume calculations for surface atoms that are not surrounded or are only sparsely surrounded by other atoms either are not possible or may be unreliable. In an attempt to circumvent this problem, Andersson & Hovmöller rejected atoms with calculated volumes that were indeterminate or were greater than 50,Å3. In the present study, it is shown that this criterion is not sufficiently restrictive to ensure accurate volume determinations. When only strictly buried atoms are included in the volume calculations using the Voronoi algorithm, the mean density is found to be 1.47 ± 0.05,g,cm,3. In addition, an alternate procedure based on the Connolly algorithm that permits all protein atoms to be included in volume calculations gives 1.43 ± 0.03,g,cm,3 for the mean density of the same set of proteins. The latter two calculated values are mutually consistent and are in better agreement with the experimental value. [source] | |||||||||||||