New Steiglitz-Mcbride adaptive lattice notch filters Cousseau, Juan Edmundo; Scoppa, Juan P.; Doñate, Pedro Darío Two novel adaptive notch filters are presented. The updating algorithms are based on the Steiglitz-McBride error criterion minimization and the basic realizations of the notch filters are all-pass based lattice filters. The proposed realizations represent an extension of a previous ad-hoc scheme for adaptive notch filtering and avoid finding the roots of a high order polynomial to obtain the unknown frequencies of interest. Since the structure is based on the lattice realization, suitable properties with finite length precision realizations can be expected. Computer simulations are included to verify the adaptive filter performance when compared with alternative realizations.

A mathematical model for zoning of protected natural areas Verdiell, Adriana Beatriz; Sabatini, M.; Maciel, Maria Cristina; Rodríguez Iglesias, Ricardo Manuel When formulated in mathematical terms, the problem of zoning a protected natural area subject to both box and spatial constraints results in a combinatorial optimization problem belonging to the NP-hard class. This fact and the usual dimension of the problem (regularly in the tens of thousands order) suggest the need to apply a heuristic approach. In this contribution we describe a quantitative method for zoning protected natural areas based on a simulated annealing algorithm. Building upon previous work by Bos (1993), we introduce three main innovations (a quadratic function of distance between land units, a non-symmetric matrix of compatibilities among uses, and a spatial connection constraint) that make the approach applicable for ecological purposes. When applied to solving small-size simulated problems, the results were indistinguishable from those obtained via an exact, enumerative method. A coarse-scale zoning of Talampaya National Park (Argentina) rendered maps remarkably similar to those produced by subject area experts using a non-quantitative consensus-seeking approach. Results are encouraging and show particular potential for the periodical update of zoning of protected natural areas. Such a capability is crucial for application in developing countries where both human and financial resources are usually scarce but still critical for updating zoning and management plans.

Interaction of catechol and gallic acid with titanium dioxide in aqueous suspensions. 1. Equilibrium studies Araujo, Paula Zulema; Morando, Pedro Juan; Blesa, Miguel Angel The adsorption isotherms of catechol (1,2-dihydroxybenzene) and gallic acid (3,4,5-trihydroxybenzoic acid) onto titanium dioxide (Degussa P-25) were measured at various pH values and room temperature using attenuated total reflection Fourier transform infrared (FTIR-ATR) data, processed by singular value decomposition. The affinity is largely pH independent, although the deprotonatation of the carboxylic group in gallic acid might produce a slight increase in the affinity. Catechol was shown to form two complexes, with Langmuir stability constants log K of 4.66 (strong mode) and 3.65 (weak mode). Both complexes have the same spectral signature, and mononuclear and binuclear chelate structures are proposed for them. Gallic acid chemisorbs by complexation through two -OH groups and forms one complex only, log K= 4.70. The third -OH and the pendant carboxylate do not influence much the stability of the surface complex. Comparison with literature data demonstrates that the affinity of 4-chlorocatechol is also similar, whereas 2,3-dihidroxynaphthalene and 4-nitrocatechol form more stable complexes, probably because of the solvation contribution to the overall Gibbs adsorption energy. All quoted constants refer to the surface complexation equilibria written as follows: (≡Ti-OH) 2 + H2L = (≡Ti)2-L + 2H2O, i.e., as electroneutral processes. The FTIR-ATR spectra of the surface complexes are also discussed. © 2005 American Chemical Society.

A constitutive equation and generalized Gassmann modulus for multimineral porous media Carcione, Jose M.; Helle, Hans B.; Santos, Juan Enrique; Ravazzoli, Claudia Leonor We derive the time-domain stress-strain relation for a porous medium composed of n - 1 solid frames and a saturating fluid. The relation holds for nonuniform porosity and can be used for numerical simulation of wave propagation. The strain-energy density can be expressed in such a way that the two phases (solid and fluid) can be mathematically equivalent. From this simplified expression of strain energy, we analogize two-, three-, and n-phase porous media and obtain the corresponding coefficients (stiffnesses). Moreover, we obtain an approx imation for the generalized Gassmann modulus. The Gassmann modulus is the bulk modulus of a saturated porous medium whose matrix (frame) is homogeneous. That is, the medium consists of two homogeneous constituents: a mineral composing the frame and a fluid. Gassmann's modulus is obtained at the low-frequency limit of Biot's theory of poroelasticity. Here, we assume that all constituents move in phase, a condition similar to the dynamic compatibility condition used by Biot, by which the P-wave velocity is equal to Gassmann's velocity at all frequencies. Our results are compared with those of the Berryman-Milton (BM) model, which provides an exact generalization of Gassmann's modulus to the three-phase case. The model is then compared to the wet-rock moduli obtained by static finite-element simulations on digitized images of microstructure and is used to fit experimental data for shaly sandstones. Finally, an example of a multimineral rock (n > 3) saturated with different fluids is given.

Sensitized photooxidation of thyroidal hormones. Evidence for heavy atom effect on singlet molecular oxygen [O2(1Δ g)]-mediated photoreactions Miskoski, Sandra; Soltermann, Arnaldo Teseo; Molina, Patricia Gabriela; Günther, Mauricio German; Zanocco, Antonio L.; Garcia, Norman Andino Thyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photo-oxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5-dliodothyronine,3,3′,5- triiodothyronine and 3,3′,5,5′-tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3-iodotyrosine and 3,5-diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1Δg,)]- mediated and superoxide ion-mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 108-109 M-1 s-1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type-II (O2(1Δg) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, kγ, and the quotient between reactive and overall rate constants (kγ/kt, values, in the range of 0.7-0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem-crossrag deactivation route within the encounter complex with the concomitant reduction of effective photooxidation.

Cambios del fósforo en suelos bajo diferentes rotaciones de cultivos Suñer, Liliana; Galantini, Juan Alberto; Rosell, Ramon Antonio Los contenidos de fósforo (P) total del suelo pueden ser relativamente altos, desde 200 a 5000 µg g-1 (Kuo, 1996), pero la capacidad del suelo de proveer P es muy variable. En la región pampeana, sólo una pequeña fracción que varía de 5 a 20 µg P g-1 está disponible para los cultivos (García, 2001). De esta manera, aún cuando la reserva de P total en el suelo exceda ampliamente los requerimientos del cultivo, éste podría sufrir deficiencias.

Análisis Textural de Cuarzo Hidrotermal del Depósito El Pantanito, provincia de Mendoza: nuevos aportes sobre su génesis; Hydrothermal quartz textural analysis from El Pantanito epithermal ore deposit, province of Mendoza: New contributions on its genesis. Rubinstein, Nora Alicia; Gargiulo, Maria Florencia El análisis textural del cuarzo hidrotermal del depósito El Pantanito, permitió realizar nuevos aportes sobre la génesis de esta mineralización epitermal de Au de baja sulfuración. Este depósito se localiza en el Bloque de San Rafael, provincia de Mendoza y está alojado en una secuencia volcánica permo-triásica, con características geoquímicas transicionales entre un régimen de subducción y uno de intraplaca continental. La ocurrencia conjunta de pseudomorfos de cuarzo según calcita, sílice coloforme - crustiforme y adularia, permite establecer que el nivel de erosión se encuentra dentro de la paleozona de ebullición ascendente. La superposición de texturas típicas de diferentes profundidades de formación, sugiere un proceso de tipo telescópico producido por la propagación, en profundidad, del frente de ebullición y por lo tanto de la zona de depositación de metales preciosos.; Hydrothermal quartz textural analysis from El Pantanito epithermal ore deposit, province of Mendoza: New contributions on its genesis. Hydrothermal quartz textural analysis from El Pantanito ore deposit, provide new information about the genesis of this low sulphidation Au epithermal mineralization. It is located in the San Rafael Massif, province of Mendoza, Argentina, and is hosted by a permo-triassic volcanic sequence with geochemical characteristics transitional between subduction and continental intraplate settings. The combined occurrence of calcite pseudomorphically replaced by quartz, crustiform-colloform silica and adularia, reflect that the erosion level is within the paleozone of boiling upflow. Overprinting of textures generated at different depths within the deposit, suggests telescoping produced by downward propagation of the boiling front and therefore the domain of precious metal deposition.

Mass transfer studies at rotating cylinder electrodes of expanded metal Grau, Javier Mario; Bisang, Jose Maria Mass transfer has been studied at rotating cylinder electrodes of expanded metal using the reduction of ferricyanide as test reaction. The experimental data are well correlated by an empirical expression between the Sherwood number and the Reynolds number both in terms of the hydraulic diameter as characteristic length and including two additional dimensionless parameters in order to characterize the geometry of the expanded metal. Comparisons of the mass-transfer performance of the expanded metal electrodes with other three-dimensional structures are made.

Neuronal and astroglial alterations in the hippocampus of a mouse model for type 1 diabetes Revsin, Yanina; Saravia, Flavia Eugenia; Roig, Paulina; Lima, Analia Ethel; de Kloet, E. Ronald; Homo Delarche, Francoise; de Nicola, Alejandro Federico The influence of diabetes mellitus on brain pathology is increasingly recognized. Previous contributions of our laboratory demonstrated in models of type 1 diabetes (nonobese diabetic and streptozotocin (STZ)-treated mice), a marked astrogliosis and neurogenesis deficit in hippocampus and increased expression of hypothalamic neuropeptides. In the present investigation, we further analyzed alterations of astroglia and neurons in the hippocampus of mice 1 month after STZ-induced diabetes. Results showed that these STZ-diabetic mice presented: (a) increased number of astrocytes positive for apolipoprotein-E (Apo-E), a marker of ongoing neuronal dysfunction; (b) abnormal expression of early gene products associated with neuronal activation, including a high number of Jun + neurons in CA1 and CA3 layers and dentate gyrus, and of Fos-expressing neurons in CA3 layer; (c) augmented activity of NADPH-diaphorase, linked to oxidative stress, in CA3 region. These data support the concept that uncontrolled diabetes leads to hippocampal pathology, which adjoin to changes in other brain structures such as hypothalamus and cerebral cortex.

Vibrational spectra of Hg3TeO6 and Hg2TeO5 Baran, Enrique José; Weil, Matthias The infrared and Raman spectra of the crystalline hexaoxotellurates Hg3TeO6 and Hg2TeO5 were recorded and discussed on the basis of a site symmetry analysis derived from known structural data. Approximate values for the Tesingle bondO bond force constants are reported and some comparisons with related species are made.

Arsenic concentration in water and bovine milk in Cordoba, Argentina. Preliminary results Pérez Carrera, Alejo Leopoldo; Fernandez Cirelli, Alicia The Chaco Pampean Plain of central Argentina constitutes one of the largest regions of high arsenic (As) groundwaters known, covering around 1r106 km2 (Smedley & Kinniburg, 2002; Farı´as et al. 2004). The high-As groundwaters are from Quaternary deposits of loess (mainly silt) with intermixed rhyolitic or dacitic volcanic ash (Nicolli et al. 1989, Smedley et al. 1998, 2002). Early in the last century an endemic disease due to contamination of drinking water with arsenic was recognised. This disease is called HACRE (Hidroarsenicismo Crónico Regional Endémico, Chronic Endemic Regional Hydroarsenism) and is connected with a particular type of skin cancer (Astolfi et al. 1981)

Pharmacokinetics and synovial fluid concentrations of flurbiprofen enantiomers in horses: chiral inversion Soraci, Alejandro Luis; Tapia, Maria Ofelia; Garcia, Jorge Flurbirpofen (FBP), a member of the 2-aryl propionate nonsteroidal anti-inflammatory drug class, has potent anti-inflammatory and analgesic properties. The commercial preparation is a racemic mixture of the R(−) and S(+) enantiomers of FBP. In this study, R(−) and S(+) FBP were used to investigate the metabolic chiral inversion. Each enantiomer was administered separately (0.25 mg/kg) and in a racemic mixture (0.5 mg/kg) intravenously to horses. Plasma and synovial concentration of each enantiomer was determined and the disposition of each was analyzed. After intravenous administration of R(−) FBP and S(+) FBP to horses no chiral inversion was detected. After the administration of the FBP racemate and individual enantiomers no differences were observed between pharmacokinetic parameters [t1/2â (h), Cl (L/h·kg), AUC (ìg·h/mL), Vss (L/kg) and MRT (h)] for R(−) and S(+) FBF. Synovial fluid concentrations of both FBP enantiomers were lower than plasma concentrations and no stereoselective differences were detected. These data indicate that the disposition of FBF in horses is not enantioselective and demonstrate a difference in the pharmacokinetic behavior of the enantiomers as compared with other 2-aryl-propionic acids, such as carprofen, ketoprofen and vedaprofen in the horse.

Primates fósiles en la Patagonia : elementos para una filogenia de los Platirrinos Tejedor, Marcelo Fabian Los primates fósiles de la Patagonia tienen enorme relevancia para comprender la sistemática y filogenia de los platirrinos neotropicales. En las provincias argentinas de Neuquén, Chubut y Santa Cruz, se han descubierto al menos 8 especies incluidas en 6 géneros de platirrinos fósiles del Mioceno inferior a medio. Estos son representantes de las subfmilias Cebinae, Pitheciinae y posiblemente Atelinae, y fueron datados entre 20 y 15.8 millones de años.

Double Hopf bifurcation analysis using frequency domain methods Itovich, Griselda Rut; Moiola, Jorge Luis The dynamic behavior close to a non-resonant double Hopf bifurcation is analyzed via a frequency-domain technique. Approximate expressions of the periodic solutions are computed using the higher order harmonic balance method while their accuracy and stability have been evaluated through the calculation of the multipliers of the monodromy matrix. Furthermore, the detection of secondary Hopf or torus bifurcations (Neimark–Sacker bifurcation for maps) close to the analyzed singularity has been obtained for a coupled electrical oscillatory circuit. Then, quasi-periodic solutions are likely to exist in certain regions of the parameter space. Extending this analysis to the unfolding of the 1:1 resonant double Hopf bifurcation, cyclic fold and torus bifurcations have also been detected in a controlled oscillatory coupled electrical circuit. The comparison of the results obtained with the suggested technique, and with continuation software packages, has been included.

Antioxidants and methimazole in the treatment of Graves' disease: Effect on urinary malondialdehyde levels Guerra, Liliana Noemi; Rios, Maria del Carmen; Miler, Eliana Andrea; Moiguer, Silvia; Karner, Mirta; Burdman, Jose Adolfo We have postulated that metabolic oxidation could be the source of signs and symptoms of hyperthyroidism. The present study was designed to evaluate urinary malondialdehyde levels in Graves' disease and compare this oxidative stress biomarker with the clinical evolution of patients suffering this illness. We evaluated the concentration of urinary and serum malondialdehyde (MDA) in 36 patients with Graves' disease. Patients were treated with the antithyroid drug methimazole (MMI; Group A) or antioxidant mixture (200 mg vitamin E, 3 mg β-carotene, 250 mg vitamin C, 1 mg Cu, 7.5 mg Zn, 1.5 mg Mn, and 15 μg Se; Group B). MDA concentrations were higher in hyperthyroid patients compared to euthyroid controls, and a positive correlation was observed between serum and urinary MDA levels. Group A decreased urinary MDA to control values. There was a positive correlation between the clinical score and the heart rate of patients with urinary MDA before and during the treatment with MMI (Group A). Similar results were observed after treatment with the antioxidant mixture. Urinary MDA might be a good parameter in the follow-up of patients during MMI treatment. We proposed that oxidative stress correlates with signs and symptoms of hyperthyroidism.

Insecticide resistance in Argentine populations of tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae); Resistência a Inseticidas em Populações Argentinas de Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) Lietti, Marcela; Botto, Eduardo Norberto; Alzogaray, Raúl Adolfo The tomato leafminer, Tuta absoluta (Meyrick), is one of the key pests of tomato in Argentina. Since its dispersal in the 1970s, chemical control has been the main method of controlling it. However, reduced efficacy of some of the recommended insecticides has been observed since the 1980s. The aim of this work was to study the toxicity of three insecticides widely used in chemical control of T. absoluta (abamectin, deltamethrin and methamidophos) on larvae from a laboratory susceptible population (CASTELAR) and two greenhouse populations (ROSARIO and BELLA VISTA). Insecticides were dissolved in acetone and topically applied to the mid-dorsal abdominal region of two-day old 4th instar larvae. LD50 values were estimated and the Resistance Ratio (RR) for each insecticide was calculated (RR = LD50 value of each greenhouse population/LD50 value of the susceptible population). ROSARIO and BELLA VISTA populations showed the following RRs values: > 68.38 for deltamethrin; 2.48 and 3.49 for abamectin, respectively; and 0.79 and 0.86 for metamidophos, respectively. Deltamethrin resistance observed in ROSARIO could be due to the high selective pressure exerted by pyrethroids in this location. Deltamethrin resistance in BELLA VISTA is more difficult to explain, because pyrethroids were scarcely used in the greenhouse where the insects were sampled. The incipient abamectin resistance detected in the BELLA VISTA population could result from the frequent use of this insecticide in this location, although natural variation can not be discarded.; A traça-do-tomateiro, Tuta absoluta (Meyrick), é uma das pragas chaves no tomateiro na Argentina. O controle químico tem sido o principal método de controle empregado a partir da sua dispersão nos anos 70. Contudo, tem-se observado uma redução na eficácia de alguns dos inseticidas recomendados a partir da década de 80. O objetivo deste trabalho foi estudar a toxicidade de três inseticidas amplamente usados no controle químico de T. absoluta (abamectina, deltametrina e metamidofós) em larvas de uma população susceptível de laboratório (CASTELAR) e duas populações colectadas em casa de vegetação (ROSARIO e BELLA VISTA). Inseticidas foram diluídos em acetona e aplicados topicamente na região dorsal mediana do abdome de larvas no segundo dia do quarto estágio larval. Para cada inseticida estimou-se o LD50 e calculou-se o Nível de Resistência (NR = LD50 de cada população de casa de vegetação/LD50 população de laboratório). As populações de ROSARIO e BELLA VISTA mostraram os seguintes NRs: > 68.38 para deltametrina; 2.48 e 3.49 para abamectina, respetivamente; e 0.79 e 0.86 para metamidofós, respetivamente. A resistência a deltametrina observada em ROSARIO pode ser resultante da alta pressão seletiva exercida pelos piretróides nessa localidade. A resistência incipiente a abamectina detectada em BELLA VISTA pode ter sido causado pelo uso freqüente do inseticida nessa localidade ou pode estar associada à variação natural.

Endothelin-1 stimulates the Na+/Ca2+ exchanger reverse mode through intracellular Na+ (Na+i)-dependent and Na+i-independent pathways Aiello, Ernesto Alejandro; Villa-Abrille, María Celeste; Dulce, Raul; Cingolani, Horacio Eugenio; Perez, Nestor Gustavo This study aimed to explore the signaling pathways involved in the positive inotropic effect (PIE) of low doses of endothelin-1 (ET-1). Cat papillary muscles were used for force and intracellular Na(+) concentration (Na(+)(i)) measurements, and isolated cat ventricular myocytes for patch-clamp experiments. ET-1 (5 nmol/L) induced a PIE and an associated increase in Na(+)(i) that were abolished by Na(+)/H(+) exchanger (NHE) inhibition with HOE642. Reverse-mode Na(+)/Ca(2+) exchanger (NCX) blockade with KB-R7943 reversed the ET-1-induced PIE. These results suggest that the ET-1-induced PIE is totally attributable to the NHE-mediated Na(+)(i) increase. However, an additional direct stimulating effect of ET-1 on NCX after the necessary increase in Na(+)(i) could occur. Thus, the ET-1-induced increase in Na(+)(i) and contractility was compared with that induced by partial inhibition of the Na(+)/K(+) ATPase by lowering extracellular K(+) (K(+)(o)). For a given Na(+)(i), ET-1 induced a greater PIE than low K(+)(o). In the presence of HOE642 and after increasing contractility and Na(+)(i) by low K(+)(o), ET-1 induced an additional PIE that was reversed by KB-R7943 or the protein kinase C (PKC) inhibitor chelerythrine. ET-1 increased the NCX current and negatively shifted the NCX reversal potential (E(NCX)). HOE642 attenuated the increase in NCX outward current and abolished the E(NCX) shift. These results indicate that whereas the NHE-mediated ET-1-induced increase in Na(+)(i) seems to be mandatory to drive NCX in reverse and enhance contractility, Na(+)(i)-independent and PKC-dependent NCX stimulation appears to additionally contribute to the PIE. However, it is important to stress that the latter can only occur after the primary participation of the former.

Plant functional traits, herbivore selectivity and response to sheep grazing in Patagonian steppe grasslands Cingolani, Ana María; Posse Beaulieu, Gabriela; Collantes, Marta Beatriz 1. In some ecosystems there is a positive feedback between forage quality and grazing intensity. This involves three components of plant tolerance to grazing: functional traits, herbivore selectivity and response to grazing. We analysed the relationships between these components at species and community levels in Patagonian steppe grasslands. 2. We measured plant functional traits [height, specific leaf area (SLA) and foliar toughness] and estimated sheep selectivity and grazing response indices for 35 plant species. Sheep selectivity indices were obtained from microhistological and species availability data, and grazing response indices from species abundances in sites with contrasting grazing intensities. We performed correlations and multiple regressions among the three types of variables across the pool of 35 species. 3. To analyse data at the community level, we computed weighted averages of traits and sheep selectivity indices for 34 floristic samples taken from each side of 17 fence lines with contrasting grazing intensities. Correlations between mean trait values and sheep selectivity across the 34 samples, and paired comparisons of those variables between sides of the fences, were performed. 4. Taller plants had leaves with lower SLA and/or higher toughness. Short species of intermediate toughness were selected more often by sheep, while SLA was not related to sheep selectivity. Short species with high SLA increased with grazing, while toughness and sheep selectivity were unrelated to grazing response. 5. At the community level, short swards with high average SLA had high selectivity indices and were more abundant on the most intensively grazed sides of fence lines. Leaf toughness was unrelated to other traits or to sheep selectivity, and showed no significant response to grazing. 6. Synthesis and applications. Intensive grazing can increase the forage value of grasslands by the creation of lawns dominated by tolerant species. However, results from this study showed that some plant species that were avoided by grazers also increased, indicating a potential risk of a shift in composition of grazing lawns towards states of low forage value. This suggests that periodic resting of lawns could be a good management strategy to favour palatable species, thereby minimizing the risk of undesirable shifts in the overall species composition.

Processes of Evolutionary Self-Organization in High Inflation Experiences Tohmé, Fernando Abel; Dabús, Carlos Darío; London, Silvia We study some features of the processes that have generated high inflation in Latin- American countries. The statistical evidence shows that these inflationary experiences are fractional brownian noises. Several authors showed that self-organized criticality (SOC) processes may constitute the best explanation of the origin of such noises. But this hypothesis requires that the underlying structure remains timeinvariant. We conjecture, instead, that the economic structures evolve in time being, at each stage of their evolution, self-organized structures. We find that such ESO (evolutionary self-organized) processes still generate fractional brownian noises. Thus, they seem to provide a better explanation for the economic phenomenon of high inflation.

Un código para la nación: familia, mujeres, derechos de propiedad y herencia en Argentina durante el siglo XIX Zeberio, Blanca Liliana La construcción de un nuevo orden social y político en la Argentina del siglo XIX presuponía, entre otros aspectos, la creación de un aparato jurídico institucional que sentara las bases de una sociedad centrada en el individuo como sujeto y creara reglas que aseguraran la consolidación de los mercados y de la propiedad privada...