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Search Results: 1 - 10 of 219732 matches for " C. Salvo "
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Enhancement of microbial motility due to speed-dependent nutrient absorption
Mario E. Di Salvo,C. A. Condat
Physics , 2013, DOI: 10.1088/1478-3975/11/1/016004
Abstract: Marine microorganisms often reach high swimming speeds, either to take advantage of evanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part of their energetic budget must be allocated to motion, it is reasonable to assume that some fast-swimming microorganisms may increase their nutrient intake by increasing their speed v. We formulate a model to investigate this hypothesis and its consequences, finding the steady state solutions and analyzing their stability. Surprisingly, we find that even modest increases in nutrient absorption may lead to a significant increase of the microbial speed. In fact, evaluations obtained using realistic parameter values for bacteria indicate that the speed increase due to the enhanced nutrient absorption may be quite large.
Latent Class Approach to Estimate the Willingness to Pay for Transit User Information  [PDF]
Pietro Zito, Giuseppe Salvo
Journal of Transportation Technologies (JTTs) , 2012, DOI: 10.4236/jtts.2012.23021
Abstract: The aim of analysis is to understand how unreliable information influences user behaviour and how much it discourages public transport use. For this purpose, a Stated Preference Survey was carried out in order to know the preferences of public transport users relating to information needs and uncertainty on the information provided by Advanced Traveller Information System (ATIS). The perceived uncertainty is defined as information inaccuracy. In our study, we considered the difference between forecasted or scheduled waiting time at the bus stop and/or metro station provided by ATIS, and that experienced by user, to catch the bus and/or metro. A questionnaire was submitted to an appropriate sample of Palermo’s population. A Latent Class Logit model was calibrated, taking into account attributes of cost, information inaccuracy, travel time, waiting time, and cut-offs in order to reveal preference heterogeneity in the perceived information. The calibrated model showed various sources of preference heterogeneity in the perceived information of public transport users as highlighted by the analysis reported. Finally, the willingness to pay was estimated, confirming a great sensitivity to the perceived information, provided by ATIS.
Maxwell’s Dynamical Philosophy: An Early Solution to the Problem of a Discrepancy between Particles and Waves  [PDF]
Salvo D’Agostino
Advances in Historical Studies (AHS) , 2014, DOI: 10.4236/ahs.2014.33012
Abstract: J. C. Maxwell contributed to an important philosophy of science, the so-called Dynamical Philosophy and Dynamical Approach to his theories. He meant it by a Dynamical Approach a theory of motions of the moving particle that could dispense with the detailed mechanism of motion. In order to develop this type of approach, he applied a modified form of Lagrange's equations in his 1865 essay “A Dynamical Theory of the Electromagnetic Field” and in his master opus “A Treatise on Electricity and Magnetism”. But an attentive historical research has also realized that he used an analogous approach in his contribution to a kinetic theory of gases, the well known statistical law of velocities.
A Good Chance for the Cat’s Life: Erwin Schroedinger’s New Statistics and a Second Quantization Theory of Quantum  [PDF]
Salvo D’Agostino
Advances in Historical Studies (AHS) , 2015, DOI: 10.4236/ahs.2015.41001
Abstract: In his paper on the Cat’s uncertain situation between life and death, S. intended to criticize the Copenhagen interpretation of Quantum Mechanics and, conversely, to assert the consistency of his own wavelike view of the theory. His ideas contrasted with Heisenberg and Bohr’s positions, but also with Einstein’s attempt at a classically statistical interpretation of a quantum theory. His criticism therefore did not intend to discredit the whole Quantum Mechanics. In the fifties, he proposed a second quantization approach to a many particles state of the theory, which included his New Statistics. He asserted that the new approach modified some aspects of his famous 1926 equations. In my paper, I argue that S.’s new ideas in the fifties are related to his 1920 and 1926 contributions on rarified gas theory.
An Overview of the Nineteenth and Twentieth Centuries’ Theories of Light, Ether, and Electromagnetic Waves  [PDF]
Salvo D’Agostino
Advances in Historical Studies (AHS) , 2016, DOI: 10.4236/ahs.2016.51001
Abstract: Johannes Kepler, the seventeenth century celebrated astronomer, considered vision as the effect of its alleged cause—the Lumen. Since many centuries, scientists and philosophers of Light were especially interested in theories and experiments on the cause-effect relationship between our vision and its alleged cause. But the Nineteenth and Twentieth Centuries’ contributions of Helmholtz, Maxwell, Hertz, and Lorentz, proved that Light was an electromagnetic wavelike phenomenon, which propagated trough space or ether by an exceptionally high velocity. In my paper I analyze some of the reasons that might justify the controversies among the major experts in Physics and Electrodynamics. In 1905 Albert Einstein found that abolishing Ether would remarkably improve his new Special Relativity theory, and Maxwell’s and Hertz’s Electrodynamics. His theory was accepted by a large majority of physicists, Max Planck included, but he also found a ten-year silence on the side of Poincaré, and moderate oppositions from Lorentz, the great expert in classical Electrodynamics.
Equivalence Principle and Ether: Two Revolutionary Kernels of Einstein’s General Relativity  [PDF]
Salvo D’agostino
Advances in Historical Studies (AHS) , 2016, DOI: 10.4236/ahs.2016.55019
Abstract: Einstein’s discovery of the Equivalence Principle is to be considered as the most fundamental concept at the origin of his General Relativity. I highlight that the ether problem is related with Enstein’s conception of gravitational waves as a perturbation of the space-time curvature, formalized as a specific space-time process, and not as the effect of a whatever supporting medium. Quite differently, the nineteenth century field theory of gravitation supported by physicists such as Maxwell, Heaviside, and Hertz, was based on a search for substantial ether, and on a parallelism with Maxwell’s theory of electromagnetic waves. The negative results of their theories proved that parallelism was a wrong approach. Einstein’s genius superseded their approach by considering that it was not a matter of the ether’s constitution, but of a fundamental change in the role and nature of physics. In my paper I refer to Einstein’s different approaches to ether since his 1905 Special Relativity up to his 1950’ views. I argue that his different attempts were symptoms of the difficulty of his revolutionary innovation.
RELACIóN DE LA ESTRUCTURA ANATóMICA CON LA PERMEABILIDAD Y TASA DE SECADO DE LA MADERA DE PINUS RADIATA D.DON
Linette SALVO
MADERAS : Ciencia y Tecnología , 2004,
Abstract:
A teoria dos jogos e as negocia es da ALCA
Salvo, Mauro
Análise , 2007,
Abstract: Este artigo tem como objetivo o histórico das negocia es para a forma o da área de Livre Comércio das Américas - LACA, levando-se em conta a abordagem da teoria dos jogos. Busca-se apontar os erros e acertos das decis es tomadas, principalmente pelo Brasil, além de identificar as estratégias adotadas para cada um dos jogadores (ou grupo deles) a fim de antecipar futuras decis es e caminhos a serem seguidos. Em suma, tentar-se-á aplicar a teoria dos jogos ao caso da ALCA com vista a responder determinadas perguntas, tais como: o Brasil adotou a estratégia correta? Quais concess es podemos ou devemos tomar e quais podemos ou devemos demandar? Como solucionar impasses e avan ar no jogo? O Brasil tem chance de obter êxito nas negocia es? Há um equilíbrio possível?
Diagnóstico de la infección por Treponema pallidum en pacientes con sífilis temprana y neurosífilis mediante reacción de la polimerasa en cadena Laboratory diagnosis of Treponema pallidum infection in patients with early syphilis and neurosyphilis through a PCR-based test
Patricia García C,Bruno Grassi C,Félix Fich S,Aurelio Salvo L
Revista chilena de infectología , 2011,
Abstract: La sífilis es una enfermedad de transmisión sexual producida por Treponema pallidum, cuyo diagnóstico se realiza presuntivamente basándose en aspectos clínicos y análisis de especificidad limitada. La reacción de la polimerasa en cadena (RPC) ha sido planteada como una alternativa diagnóstica de mayor sensibilidad y especificidad. El objetivo de este trabajo fue validar una RPC para el diagnóstico de sífilis temprana (ST) y neurosífilis (NS). Se utilizaron muestras de lesiones muco-cutáneas y de LCR de pacientes con sospecha de cursar ST y NS respectivamente, previamente diagnosticados, utilizando un estándar de oro ampliado. La RPC fue realizada con partidores dirigidos al gen tpN47. De las 21 muestras de pacientes con ST, la RPC resultó positiva en 20, lo que resulta en una sensibilidad clínica de 95%. De las 8 muestras de pacientes con NS, la RPC resultó positiva en 4, obteniéndose una sensibilidad clínica de 50%. La especificidad clínica para ST y NS fue de 100%. La excelente sensibilidad y especificidad de la RPC para muestras muco-cutáneas permitió la exitosa implementación de este análisis en nuestro laboratorio para el diagnóstico de rutina. Si bien la sensibilidad de la RPC en LCR es baja, es muy útil para apoyar el diagnóstico clínico. Syphilis is a sexually transmitted disease caused by Treponema pallidum. The diagnosis is based mainly in clinical presentation and non-specific assays. PCR-based diagnosis has been suggested as an attractive alternative method. The aim of this study was the validation of a PCR-based test for the diagnosis of early syphilis (ES) and neurosyphilis (NS). Clinical samples of mucocutaneous lesions and cerebrospinal fluid (CSF) specimens from patients previously diagnosed for ES and NS respectively using an enlarged gold standard, were tested by PCR. The reaction was done using primers targeting the tpN47gene. Twenty out of 21 mucocutaneous samples from patients diagnosed with ES were positive by PCR, with a clinical sensitivity of 95%. Four out of 8 CSF samples from patients previously diagnosed with NS were positive by PCR, with a clinical sensitivity of 50%. The clinical specificity for both ES and NS was 100%. The PCR sensitivity and specificity for mucocutaneous samples allowed us to implement this assay in our laboratory for routine diagnosis. Although the sensitivity of the PCR in CSF was low, it may be useful to support clinical diagnosis.
ESTUDIO EXPLORATORIO DE LA VARIABILIDAD RADIAL Y APICAL DEL TAMA?O Y FRECUENCIA DE LOS CANALES RESINíFEROS EN PINO RADIATA
Ananías,R. A; Lastra,J; Salvo,L; Contreras,H; Barría,C; Peredo,M;
Maderas. Ciencia y tecnología , 2010, DOI: 10.4067/S0718-221X2010000200008
Abstract: radial and apical variation in resin canals of radiata pine were studied. the frequency and size of resin canals were examined, using microscopic techniques from a commercial software. wood samples from standing trees were taken, showing three different levels of external resin-bleeding intensity : moderate, light and intense. the variability of the resin canals were examined according to the radial position at three different heights ; bottom, breast height diameter and at the beginning of the tree top. the results show that the apical and radial variation of the size and frequency of resin canals appeared weakly correlated with the intensity level of the tree resin-bleeding of the standing radiata pine trees.
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