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Search Results: 1 - 10 of 461356 matches for " A. Tarantola "
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Ground Penetrating Radar: Analysis of point diffractors for modeling and inversion
Albane Saintenoy,A. Tarantola
Physics , 2013,
Abstract: The three electromagnetic properties appearing in Maxwell's equations are dielectric permittivity, electrical conductivity and magnetic permeability. The study of point diffractors in a homogeneous, isotropic, linear medium suggests the use of logarithms to describe the variations of electromagnetic properties in the earth. A small anomaly in electrical properties (permittivity and conductivity) responds to an incident electromagnetic field as an electric dipole, whereas a small anomaly in the magnetic property responds as a magnetic dipole. Neither property variation can be neglected without justification. Considering radiation patterns of the different diffracting points, diagnostic interpretation of electric and magnetic variations is theoretically feasible but is not an easy task using Ground Penetrating Radar. However, using an effective electromagnetic impedance and an effective electromagnetic velocity to describe a medium, the radiation patterns of a small anomaly behave completely differently with source-receiver offset. Zero-offset reflection data give a direct image of impedance variations while large-offset reflection data contain information on velocity variations.
Effect of urea treatment on the nutritive value of local sorghum and millet straw: a comparative study on growing performance of Djallonke rams
M. Mattoni,A. Schiavone,M. Tarantola,G. Ladetto
Italian Journal of Animal Science , 2010, DOI: 10.4081/ijas.2007.1s.318
Abstract: Two tons of and chopped millet and sorghum straws have been treated with an urea solution at 5% (100 kg of straw, sprinkled with 50 lt. of solution). Treated straws were used as basic diet (900 g day) associated to 100 g of cotton cake for 24 growing Djallonke rams in comparison to non treated straws. Four groups of animals were fed for 98 days with: urea treated sorghum (UTSS), not treated sorghum straw (NTSS), treated millet (UTMS), non treated millet straw (NTMS). Treated straws presented an increase of NDF of about 9%, of total nitrogen from 2 to 3 times while digestibility of dry matter increased respectively by 8,8% and 23,0% respectively in treated sorghum and millet. Also dry matter intake increased by 4,5% and 15,5% for treated sorghum and millet respectively compared to non treated. Mean weekly weight gain were significantly higher (P<0.05) for UTSS e UTMS compared to NTSS e NTMS. While the weekly weight gain, did not differed between UTSS vs. UTMS and NTSS vs. NTMS. At the end of the trial the UTSS and UTMS group presented a weight gain of about 40% and 38.7%, of their initial weight; while the gain for both NTSS and NTMS was respectively of 31.1% and 29.5%.
Effect of slaughter age on meat qualitative traits of veal calves
M.I. Tarantola,A. Schiavone,G. Preziuso,C. Russo
Italian Journal of Animal Science , 2011, DOI: 10.4081/ijas.2003.s1.343
Abstract: Veal calves breeding holds an important of bovine meat production part over all our country, as for the appreciation by the consumers for its pale coloured flesh, believed to be more digestible, than for favourable use of Frisian males that are slaughtered because they exceed the restocking of beef (Balasini, 2000)...
Altered alkaline phosphatase activity in obese Zucker rats liver respect to lean Zucker and Wistar rats discussed in terms of all putative roles ascribed to the enzyme
V. Bertone,E. Tarantola,A. Ferrigno,E. Gringeri
European Journal of Histochemistry , 2011, DOI: 10.4081/ejh.2011.e5
Abstract: Biliary complications often lead to acute and chronic liver injury after orthotopic liver transplantation (OLT). Bile composition and secretion depend on the integrated action of all the components of the biliary tree, starting from hepatocytes. Fatty livers are often discarded as grafts for OLT, since they are extremely vulnerable to conventional cold storage (CS). However, the insufficiency of donors has stimulated research to improve the usage of such marginal organs as well as grafts. Our group has recently developed a machine perfusion system at subnormothermic temperature (20°C; MP20) that allows a marked improvement in preservation of fatty and even of normal rat livers as compared with CS. We sought to evaluate the response of the biliary tree of fatty liver to MP20, and a suitable marker was essential to this purpose. Alkaline phosphatase (AlkP, EC, frequently used as marker of membrane transport in hepatocytes and bile ducts, was our first choice. Since no histochemical data were available on AlkP distribution and activity in fatty liver, we have first settled to investigate AlkP activity in the steatotic liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. The AlkP reaction in Wistar rats was in accordance with the existing data and, in particular, was present in bile canaliculi of hepatocytes in the periportal region and midzone, in the canals of Hering and in small bile ducts but not in large bile ducts. In lean ZR liver the AlkP reaction in Hering canals and small bile ducts was similar to Wistar rat liver but hepatocytes had lower canalicular activity and besides presented moderate basolateral reaction. The difference between lean Zucker and Wistar rats, both phenotypically normal animals, could be related to the fact that lean Zucker rats are genotypically heterozygous for a recessive mutated allele. In fatty liver, the activity in ductules and small bile ducts was unchanged, but most hepatocytes were devoid of AlkP activity with the exception of clusters of macrosteatotic hepatocytes in the mid-zone, where the reaction was intense in basolateral domains and in distorted canaliculi, a typical pattern of cholestasis. The interpretation of these data was hindered by the fact that the physiological role of AlkP is still under debate. In the present study, the various functions proposed for the role of the enzyme in bile canaliculi and in cholangiocytes are reviewed. Independently of the AlkP role, our data suggest that AlkP does not seem to be a reliable marker to study the initial step o
Foreword: Public health, public policy, politics and policing
Daniel Tarantola
Harm Reduction Journal , 2012, DOI: 10.1186/1477-7517-9-22
Abstract: Harm reduction, as a public health, encompasses a wide and diverse array of approaches aimed at minimizing individual and collective negative impacts of risky behaviours. Road safety measures such as speed limitation and the enforcement of seat belt and motorcycle helmet legislation are examples of such measures. In the realm of HIV/AIDS, harm reduction approaches have had significant impacts on HIV transmission among men who have sex with men (MSM) and injecting drug users (IDUs) as well as in the context of heterosexual and transactional sex. Elimination of risk, vulnerability and impact will remain remote goals until a cure and highly effective vaccines become available, and most-at-risk populations are no longer subjected to discrimination and social exclusion. Until then, harm reduction approaches have proven the approaches of choice, demonstrated by declining HIV prevalence and incidence over the last two decades in populations where prevention and early access to treatment have been instituted at scale.Evidence abounds supporting the introduction in public policy and in practice of measures aimed principally at minimizing the spread of HIV (and Hepatitis B and C) resulting from the sharing of unsterile paraphernalia. Those who have patiently and rigorously collected, analysed and disseminated this evidence have produced a very robust body of evidence for policy change. Often in adverse environments, they have established that making sterile injection equipment available to drug users and switching from injection – involving high risks of blood-borne contamination – to less harmful forms of drug use, including the oral administration of opiate substitutes, substantially lowers risk and transmission of HIV. They have repeatedly shown that these measures are effective on the individual and community levels when combined with individual counselling, community networking and public information. Notably, they have also documented that these approaches do not impact
Facing the reality of AIDS - a 15-year process?
Tarantola Daniel
Bulletin of the World Health Organization , 2001,
Stress and strain in symmetric and asymmetric elasticity
Albert Tarantola
Physics , 2009,
Abstract: Usual introductions of the concept of motion are not well adapted to a subsequent, strictly tensorial, theory of elasticity. The consideration of arbitrary coordinate systems for the representation of both, the points in the laboratory, and the material points (comoving coordinates), allows to develop a simple, old fashioned theory, where only measurable quantities -like the Cauchy stress- need be introduced. The theory accounts for the possibility of asymmetric stress (Cosserat elastic media), but, contrary to usual developments of the theory, the basic variable is not a micro-rotation, but the more fundamental micro-rotation velocity. The deformation tensor here introduced is the proper tensorial equivalent of the poorly defined deformation "tensors" of the usual theory. It is related to the deformation velocity tensor via the matricant. The strain is the logarithm of the deformation tensor. As the theory accounts for general Cosserat media, the strain is not necessarily symmetric. Hooke's law can be properly introduced in the material coordinates (as the stiffness is a function of the material point). A particularity of the theory is that the components of the stiffness tensor in the material (comoving) coordinates are not time-dependent. The configuration space is identified to the part of the Lie group GL(3)+, that is geodesically connected to the origin of the group.
Image and Reciprocal Image of a Measure. Compatibility Theorem
Albert Tarantola
Mathematics , 2008,
Abstract: It is proposed that to the usual probability theory, three definitions and a new theorem are added, the resulting theory allows one to displace the central role usually given to the notion of conditional probability. When a mapping $\phi$ is defined between two measurable spaces, to each measure $\mu$ introduced on the first space, there corresponds an image $\phi[\mu]$ on the second space, and, reciprocally, to each measure $\nu$ defined on the second space the corresponds a reciprocal image $\phi^{-1}[\nu]$ on the first space. As the intersection $\cap$ of two measures is easy to introduce, a relation like $ \phi[ \mu \cap \phi^{-1} [\nu] ] = \phi[\mu] \cap \nu $ makes sense. It is, indeed, a theorem of the theory. This theorem gives mathematical consistency to inferences drawn from physical measurements.
Using pulsars to define space-time coordinates
Bartolome Coll,Albert Tarantola
Physics , 2009,
Abstract: Fully relativistic coordinates have been proposed for (relativistically) running a "GPS" system. These coordinates are the arrival times of the light signals emitted by four "satellites" (clocks). Replacing the signals emitted by four controlled clocks by the signals emitted by four pulsars defines a coordinate system with lower accuracy, but valid across the whole Solar System. We here precisely define this new coordinate system, by choosing four particular pulsars and a particular event as the origin of the coordinates.
Mathematical Basis for Physical Inference
Albert Tarantola,Klaus Mosegaard
Physics , 2000,
Abstract: While the axiomatic introduction of a probability distribution over a space is common, its use for making predictions, using physical theories and prior knowledge, suffers from a lack of formalization. We propose to introduce, in the space of all probability distributions, two operations, the OR and the AND operation, that bring to the space the necessary structure for making inferences on possible values of physical parameters. While physical theories are often asumed to be analytical, we argue that consistent inference needs to replace analytical theories by probability distributions over the parameter space, and we propose a systematic way of obtaining such "theoretical correlations", using the OR operation on the results of physical experiments. Predicting the outcome of an experiment or solving "inverse problems" are then examples of the use of the AND operation. This leads to a simple and complete mathematical basis for general physical inference.
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