On Marilda Sotomayor's extraordinary contribution to matching theory

Financial support the research grants ECO2012-31962, 2014SGR-142, and ICREA AcademiaWe report on Marilda Sotomayor's extraordinay contribution to Matching Theory on the occasion of her 70th anniversar

Acoustic impedance estimation using a gradient-based algorithm with total variation semi-norm regularization

We present an algorithm to estimate blocky images of the subsurface acoustic impedance (AI) from seismic reflection data. We use the total variation semi-norm (TV) to regularize the inversion and promote blocky solutions which are, by virtue of the capability of TV to handle edges properly, adequate to model layered earth models with sharp contrasts. In addition, the use of the TV leads to a convex objective function that can be minimized using a gradientbased algorithm that only requires matrix-vector multiplications and no direct matrix inversion. The latter makes the algorithm numerically stable, easy to apply, and economic in terms of computational cost. Besides, given appropriate a priori information, the algorithm allows to easily incorporate into the inversion scheme the low frequency trend that is missing from the data. Numerical tests on noisy 2D synthetic and field data show that the proposed method is capable of providing consistent and blocky AI images that preserve edges and the subsurface layered structure.Facultad de Ciencias Astronómicas y Geofísica

Simple and fast gradient-based impedance inversion using total variation regularization

We present an algorithm to estimate blocky images of the subsurface acoustic impedance (AI) from poststack seismic data. We regularize the resulting inverse problem, which is inherently ill-posed and non-unique, by means of the total variation semi-norm (TV). This allows us promote stable and blocky solutions which are, by virtue of the capability of TV to handle edges properly, adequate to model layered earth models with sharp contrasts. The use of the TV leads to a convex objective function easily minimized using a gradient-based algorithm that requires, in contrast to other AI inversion methods based on TV regularization, simple matrix-vector multiplications and no direct matrix inversion. The latter makes the algorithm numerically stable, easy to apply, and economic in terms of computational cost. Tests on synthetic and field data show that the proposed method, contrarily to conventional l2- or l1-norm regularized solutions, is able to provide blocky AI images that preserve the subsurface layered structure with good lateral continuity from noisy observations.Facultad de Ciencias Astronómicas y Geofísica

Acoustic impedance estimation using a gradient-based algorithm with total variation semi-norm regularization

We present an algorithm to estimate blocky images of the subsurface acoustic impedance (AI) from seismic reflection data. We use the total variation semi-norm (TV) to regularize the inversion and promote blocky solutions which are, by virtue of the capability of TV to handle edges properly, adequate to model layered earth models with sharp contrasts. In addition, the use of the TV leads to a convex objective function that can be minimized using a gradientbased algorithm that only requires matrix-vector multiplications and no direct matrix inversion. The latter makes the algorithm numerically stable, easy to apply, and economic in terms of computational cost. Besides, given appropriate a priori information, the algorithm allows to easily incorporate into the inversion scheme the low frequency trend that is missing from the data. Numerical tests on noisy 2D synthetic and field data show that the proposed method is capable of providing consistent and blocky AI images that preserve edges and the subsurface layered structure.Facultad de Ciencias Astronómicas y Geofísica

Pyridine nucleotide transhydrogenases enable redox balance of Pseudomonas putida during biodegra dation of aromatic compounds

Supporting informationThe metabolic versatility of the soil bacterium Pseudomonas putida is reflected by its ability to execute strong redox reactions (e.g., mono- and di-oxygenations) on aromatic substrates. Biodegradation of aromatics occurs via the pathway encoded in the archetypal TOL plasmid pWW0, yet the effect of running such oxidative route on redox balance against the background metabolism of P. putida remains unexplored. To answer this question, the activity of pyridine nucleotide transhydrogenases (that catalyze the reversible interconversion of NADH and NADPH) was inspected under various physiological and oxidative stress regimes. The genome of P. putida KT2440 encodes a soluble transhydrogenase (SthA) and a membrane-bound, proton-pumping counterpart (PntAB). Mutant strains, lacking sthA and/or pntAB, were subjected to a panoply of genetic, biochemical, phenomic and functional assays in cells grown on customary carbon sources (e.g., citrate) versus difficult-to-degrade aromatic substrates. The results consistently indicated that redox homeostasis is compromised in the transhydrogenases-defective variant, rendering the mutant sensitive to oxidants. This metabolic deficiency was, however, counteracted by an increase in the activity of NADP+ -dependent dehydrogenases in central carbon metabolism. Taken together, these observations demonstrate that transhydrogenases enable a redox-adjusting mechanism that comes into play when biodegradation reactions are executed to metabolize unusual carbon compounds.This work was supported by the EVOPROG (FP7-ICT-610730), ARISYS (ERC-2012-ADG-322797) and EmPowerPutida (EU-H2020-BIOTEC-2014-2015-6335536), Contracts of the European Union, and the CAMBIOS (RTC-2014-1777-3) and CONTIBUGS (PCIN-2013-040) projects of the Spanish Ministry of Economy and Competitiveness.Peer reviewe

Hasta una epistemología del concepto de cultura

PublishedEste capítulo busca dar cuenta del valor de la epistemología y del paradigma llegado el momento de definir los conceptos que acompañan a cualquier tipo de ejercicio investigativo toda vez que, a partir de ellos, se define el alcance del conocimiento que se desea producir. La importancia de los conceptos en la historiografía radica en su capacidad de sintetizar y reflejar una realidad social e intelectual específica, transformándose en categorías fundamentales para restituir, al menos, un fragmento de un acontecimiento perdido en las profundidades del tiempo histórico

High-resolution prestack seismic inversion using a hybrid FISTA least-squares strategy

A new inversion method to estimate high-resolution amplitude-versus-angle attributes (AVA) attributes such as intercept and gradient from prestack data is presented. The proposed technique promotes sparse-spike reflectivities that, when convolved with the source wavelet, fit the observed data. The inversion is carried out using a hybrid two-step strategy that combines fast iterative shrinkagethresholding algorithm (FISTA) and a standard least-squares (LS) inversion. FISTA, which can be viewed as an extension of the classical gradient algorithm, provides sparse solutions by minimizing the misfit between the modeled and the observed data, and the l1-norm of the solution. FISTA is used to estimate the location in time of the main reflectors. Then, LS is used to retrieve the appropriate reflectivity amplitudes that honor the data. FISTA, like other iterative solvers for l1-norm regularization, does not require matrices in explicit form, making it easy to apply, economic in computational terms, and adequate for solving large-scale problems. As a consequence, the FISTA+LS strategy represents a simple and cost-effective new procedure to solve the AVA inversion problem. Results on synthetic and field data show that the proposed hybrid method can obtain highresolution AVA attributes from noisy observations, making it an interesting alternative to conventional methods.Facultad de Ciencias Astronómicas y Geofísica

Karakterizacija endokrino-metaboličkog profila koji se koristi za procjenu funkcije štitnjače kod pasa pasmina engleski i francuski buldog

This study investigates whether breed or gender affect serum hormone and metabolite concentrations used to evaluate thyroid function in the Bulldog breed. Sixty-seven healthy adult English Bulldogs (n = 20), French Bulldogs (n = 17), German Shepherds (n = 15) and mongrels (n = 15) of both sexes were selected. Determination of serum total thyroxine (TT4), free thyroxine (FT4), and thyroid stimulating hormone (TSH) was performed via a competitive enzymatic chemiluminescent solid-phase immunoassay. Cholesterol and triglyceride concentrations were analyzed by spectrophotometry. Serum concentrations of TT4, FT4, TSH, cholesterol, and triglycerides for French and English Bulldogs were within the international reference ranges for the canine population. Breed had a significant effect on serum levels of TT4 (P = 0.0012) and FT4 (P<0.0001); English and French Bulldogs had higher serum TT4 and FT4 concentrations than German Shepherds and mongrels. Gender had a significant effect only on serum FT4 levels; females exhibited higher levels (P = 0.0309). Cholesterol, triglycerides, and TSH serum concentrations did not differ with breed or gender. Healthy French and English Bulldogs included in this study had higher serum concentrations of TT4 and FT4 compared with German Shepherds and mongrels, and the concentration of FT4 was also higher in females.Ovim radom istraženo je utječu li pasmina i spol na koncentracije hormona i metabolita u serumu koji služi za procjenu funkcije štitnjače u pasa pasmine buldog. Uključeno je ukupno šezdeset i sedam odraslih zdravih pasa oba spola, među kojima je bilo 20 engleskih buldoga, 17 francuskih buldoga, 15 njemačkih ovčara i 15 križanaca. Ukupni tiroksin (TT4), slobodni tiroksin (FT4) i hormon koji stimulira štitnjaču (TSH) određeni su pomoću kompetitivne enzimske kemiluminoscentne imunoanalize. Koncentracije kolesterola i triglicerida analizirane su spektrofotometrijom. Koncentracije TT4, FT4, TSH, kolesterola i triglicerida u serumu za francuske i engleske buldoge bile su unutar međunarodnih referentnih raspona za populaciju pasa. Pasmina je imala signifikantan učinak na razinu TT4 (p = 0,0012) i FT4 (p< 0,0001) u serumu, pri čemu su engleski i francuski buldozi imali veće koncentracije TT4 i FT4 u serumu nego njemački ovčari i križanci. Spol je imao signifikantan utjecaj samo na razinu FT4 u serumu, pri čemu je ta razina bila viša kod ženki (p = 0,0309). Kolesterol, trigliceridi i koncentracije TSH seruma nisu se razlikovali ovisno o pasmini ili spolu. Zdravi francuski i engleski buldozi uključeni u ovo istraživanje su, u usporedbi s njemačkim ovčarima i križancima, imali veće koncentracije TT4 i FT4 u serumu. Također, koncentracija FT4 u serumu bila je viša kod ženki

A hybrid strategy based on fast iterative shrinkage-thresholding algorithm and very fast simulated annealing: application to the prestack seismic inverse problem

With the purpose of characterizing the Earth subsurface, one of the objectives of the inversion of prestack seismic data is to determine contrasts between rock properties from the information contained in the variation of the amplitudes of the reflected compressional waves with the angle of incidence. This amplitude-versus-angle (AVA) variation can be described by various approximations to the so-called Zoeppritz equations, a set of non-linear equations that depend on the physical characteristics of the medium at each side of the interface where the compressional wave strikes. The coefficients of such approximations constitute AVA attributes that may provide important information about fluid content, a key issue for the characterization of hydrocarbon reservoirs. In this work we present a new inversion strategy to estimate efficiently and accurately high-resolution AVA attributes from prestack data. The proposed technique promotes sparse-spike reflectivities that, when convolved with the source wavelet, fit the observed data. Sparse solutions are desirable because they can be used to characterize significant and close reflectors more accurately than using conventional solutions. The inversion is carried out using a hybrid two-step strategy than combines Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) and Very Fast Simulated Annealing (VFSA). FISTA provides sparse solutions by minimizing both the misfit between the modeled and the observed data, and the l1-norm of the solution. VFSA is an stochastic computational algorithm to finding near-optimal solutions to hard optimization problems. At the first stage, FISTA sparse-solutions provide an estimate of the location in time of the main reflectors, information that is subsequently used as an initial guess for the second stage, where accurate reflectivity amplitudes are estimated by solving a more stable overdetermined inverse problem. The second stage also involves the use of VFSA for tuning the location in time of the main reflectors and the source wavelet. FISTA does not require the inversion of matrices in explicit form. At each iteration only matrix-vector multiplications are involved, making it easy to apply, economic in computational terms, and adequate for solving large-scale problems. As a result, the FISTA+VFSA strategy represents a simple and cost-effective new procedure to solve the high-resolution AVA inversion problem. Results on synthetic data show that the proposed hybrid method can obtain high-resolution AVA attributes from noisy observations, even when the number of reflectors is not known a priori and the utilized wavelet is inaccurate, making it an interesting alternative to conventional methods.Facultad de Ciencias Astronómicas y Geofísica

A hybrid strategy based on fast iterative shrinkage-thresholding algorithm and very fast simulated annealing: application to the prestack seismic inverse problem

With the purpose of characterizing the Earth subsurface, one of the objectives of the inversion of prestack seismic data is to determine contrasts between rock properties from the information contained in the variation of the amplitudes of the reflected compressional waves with the angle of incidence. This amplitude-versus-angle (AVA) variation can be described by various approximations to the so-called Zoeppritz equations, a set of non-linear equations that depend on the physical characteristics of the medium at each side of the interface where the compressional wave strikes. The coefficients of such approximations constitute AVA attributes that may provide important information about fluid content, a key issue for the characterization of hydrocarbon reservoirs. In this work we present a new inversion strategy to estimate efficiently and accurately high-resolution AVA attributes from prestack data. The proposed technique promotes sparse-spike reflectivities that, when convolved with the source wavelet, fit the observed data. Sparse solutions are desirable because they can be used to characterize significant and close reflectors more accurately than using conventional solutions. The inversion is carried out using a hybrid two-step strategy than combines Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) and Very Fast Simulated Annealing (VFSA). FISTA provides sparse solutions by minimizing both the misfit between the modeled and the observed data, and the l1-norm of the solution. VFSA is an stochastic computational algorithm to finding near-optimal solutions to hard optimization problems. At the first stage, FISTA sparse-solutions provide an estimate of the location in time of the main reflectors, information that is subsequently used as an initial guess for the second stage, where accurate reflectivity amplitudes are estimated by solving a more stable overdetermined inverse problem. The second stage also involves the use of VFSA for tuning the location in time of the main reflectors and the source wavelet. FISTA does not require the inversion of matrices in explicit form. At each iteration only matrix-vector multiplications are involved, making it easy to apply, economic in computational terms, and adequate for solving large-scale problems. As a result, the FISTA+VFSA strategy represents a simple and cost-effective new procedure to solve the high-resolution AVA inversion problem. Results on synthetic data show that the proposed hybrid method can obtain high-resolution AVA attributes from noisy observations, even when the number of reflectors is not known a priori and the utilized wavelet is inaccurate, making it an interesting alternative to conventional methods.Facultad de Ciencias Astronómicas y Geofísica