Contrast Medium Volume Optimization in Abdominal CT on Basis of Lean Body Weight

This is the final version of the article. Available from Scientific and Academic Publishing via the link in this record.Computed tomography (CT) in abdominal imaging has undergone great advances in recent years. The administration of iodinated contrast media (CM) has evolved along with the evolution of the CT equipment. The most common method for calculation of the CM volume in abdominal CT is based on total body weight (TBW), but in this way some patients get a lower dose and some other patients get a higher dose that the optimal dose they need. In the literature there are many formulas to calculate the CM volume to be administered in abdominal CT, but practice shows that the variability of enhancement is wide. The main objective of this study is to verify that the volume of intravenous CM in abdominal CT calculated on basis of lean body weight (LBW) allows good liver enhancement with small amplitude of variation around the mean, that is, with less variability in enhancement than CM volume calculated on basis of TBW. In conclusion the calculation of the volume of CM on basis of LBW translates into a low variability of liver enhancement–25.50 HU. In our results 96.05% of sample belongs to a good hepatic enhancement. If we stratify sample by groups of BMI, we also verify no significative differences between slims and fat patients when analysed mean hepatic enhancement

Inner Core Translation and the Hemispheric Balance of the Geomagnetic Field

Bulk translation of the Earth’s inner core has been proposed as an explanation of observed quasi-hemispheric seismic structure. An important consequence of inner core translation would be the generation of a spherical harmonic degree one heat flow anomaly at the inner core boundary (ICB) that would provide an inhomogeneous forcing for outer core convection. We use geodynamo simulations to investigate the geomagnetic signature of such heterogeneity. Strong hemispheric heterogeneity at the ICB is found to produce a hemispheric signature in both the morphology of the magnetic field and its secular variation; in particular, we note the formation of high-intensity flux patches at high-latitudes and American longitudes in our model with strong ICB heterogeneity. In our simulations, this model provides the best match to the Earth’s field over the past 400 years according to previously proposed measures of field structure. However, these criteria do not include the hemispheric balance of the field. We propose new criteria to measure this balance and find that our model with strong ICB heterogeneity produces the poorest match to the hemispheric balance of the historical geomagnetic field. Resolution of the hemispheric balance of the magnetic field throughout the Holocene would provide a strong test of any proposal of rapid inner core translation

Diagnóstico laboratorial de trombofilia

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Effects of oxygen depletion on soot production, emission and radiative heat transfer in opposed-flow flame spreading over insulated wire in microgravity

This paper investigates experimentally and numerically pressure effects on soot production and radiative heat transfer in non-buoyant opposed-flow flames spreading over wires coated by Low Density PolyEthylene (LPDE). Experiments, conducted in parabolic flights, consider pressure levels ranging from 50.7 kPa to 121.6 kPa and an oxidizer flowing parallel to the wire's axis at a velocity of 150 mm/s and composed of 20% O2/80% N2 in volume. The numerical model includes a detailed chemistry, a two-equation smoke-point based soot production model, a radiation model coupling the Full-Spectrum correlated-k method with the finite volume method and a simple degradation model for LDPE. An analysis of the experimental data shows that the spread rate, the pyrolysis mass flow rate, and the residence time for soot formation are independent of pressure whereas the soot formation rate is third-order in pressure. The model reproduces quantitatively the effects of pressure on soot production and captures the transition from non-smoking to smoking flames. The radiant fraction increases with pressure because of an enhancement in soot radiation whereas the contribution of radiating gases remains approximately constant over the range of pressures considered. In addition, gas radiation dominates at pressure lower than 75 kPa whereas soot radiation prevails at higher-pressure levels. Consistently with the data obtained at normal gravity, the smoke-point transition is found to occur for a radiant fraction of about 0.3 and the soot oxidation freezing temperature is estimated in the range 1350-1450K. Eventually, whatever the pressure considered, the surface re-radiation from the wire is higher than the incident radiative flux from the flame to the surface along the entire wire. This shows that radiative heat transfer contributes negatively to the heating of the unburnt LDPE and to the heat balance along the pyrolysing surface

Regulation of hypoxia-inducible factor-1α (HIF-1α) expression by interleukin-1β (IL-1β), insulin-like growth factors I (IGF-I) and II (IGF-II) in human osteoarthritic chondrocytes

Objective: Hypoxia-inducible factor 1 alpha regulates genes related to cellular survival under hypoxia. This factor is present in osteroarthritic chondrocytes, and cytokines, such as interleukin-1 beta, participate in the pathogenesis of osteoarthritis, thereby increasing the activities of proteolytic enzymes, such as matrix metalloproteinases, and accelerating cartilage destruction. We hypothesize that Hypoxia Inducible Factor-1 alpha (HIF-1α) can regulate cytokines (catabolic action) and/or growth factors (anabolic action) in osteoarthritis. The purpose of this study was to investigate the modulation of HIF-1α in human osteoarthritic chondrocytes by interleukin-1 beta (IL-1β) and insulin-like growth factors I (IGF-I) and II (IGF-II) and to determine the involvement of the phosphatidylinositol-3- kinase (PI-3K) pathway in this process. Methods: Human osteroarthritic chondrocytes were stimulated with IL-1β, IGF-I and IGF-II and LY294002, a specific inhibitor of PI-3K. Nuclear protein levels and gene expression were analyzed by western blot and quantitative reverse transcription-polymerase chain reaction analyses, respectively. Results: HIF-1α expression was upregulated by IL-1β at the protein level but not at the gene level. IGF-I treatment resulted in increases in both the protein and mRNA levels of HIF-1α, whereas IGF-II had no effect on its expression. However, all of these stimuli exploited the PI-3K pathway. Conclusion: IL-1β upregulated the levels of HIF-1α protein post-transcriptionally, whereas IGF-I increased HIF-1α at the transcript level. In contrast, IGF-II did not affect the protein or gene expression levels of HIF-1α. Furthermore, all of the tested stimuli exploited the PI-3K pathway to some degree. 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