Adaptive management of alien invasive species: putting the theory into practice Zalba, Sergio Martín; Ziller, Sílvia R. Even though often based on scarce information, many actions due to conservation ofbiodiversity need to be carried out as matters of urgency. In the case of biological invasions, this is acommon situation, as the real possibilities for controlling an invasive alien species are significantlyreduced as it establishes and spreads over natural ecosystems. Adaptive management, that is, man-agement practices planned on a solid experimental basis, allows managers to tackle urgent problemsat the same time they generate essential information to test the effectiveness of control practices andthe precision of assessments of the impacts of invasive species over natural ecosystems or of the needto carry out complementary restoration practices. The basic principles of adaptive management arepresented in this paper with examples of its application in the control of invasive alien species in thepampas of Argentina.

Copper incorporation into recombinant CotA laccase from Bacillus subtilis: characterization of fully copper loaded enzymes Durão, Paulo; Chen, Zhenjia; Fernandes, André T.; Hildebrandt, Peter; Murgida, Daniel Horacio; Todorovic, Smilja; Pereira, Manuela M.; Melo, Eduardo P.; Martins, Lígia O. The copper content of recombinant CotA laccase from Bacillus subtilis produced by Escherichia coli cells is shown to be strongly dependent on the presence of copper and oxygen in the culture media. In copper-supplemented media, a switch from aerobic to microaerobic conditions leads to the synthesis of a recombinant holoenzyme, while the maintenance of aerobic conditions results in the synthesis of a copper-depleted population of proteins. Strikingly, cells grown under microaerobic conditions accumulate up to 80-fold more copper than aerobically grown cells. In vitro copper incorporation into apoenzymes was monitored by optical and electron paramagnetic resonance (EPR) spectroscopy. This analysis reveals that copper incorporation into CotA laccase is a sequential process, with the type 1 copper center being the first to be reconstituted, followed by the type 2 and the type 3 copper centers. The copper reconstitution of holoCotA derivatives depleted in vitro with EDTA results in the complete recovery of the native conformation as monitored by spectroscopic, kinetic and thermal stability analysis. However, the reconstitution of copper to apo forms produced in cultures under aerobic and copper-deficient conditions resulted in incomplete recovery of biochemical properties of the holoenzyme. EPR and resonance Raman data indicate that, presumably, folding in the presence of copper is indispensable for the correct structure of the trinuclear copper-containing site.

Genetic typing of equine arteritis virus isolates from Argentina Echeverria, Maria Gabriela; Diaz, Silvina; Metz, German Ernesto; Serena, Maria Soledad; Panei, Carlos Javier; Nosetto, Edgardo Omar We report the nucleotide sequence and genetic diversity of four Equine Arteritis Virus (EAV) ORF 5 and 6 from Argentina isolates, obtained from asymptomatic virus-shedding stallions. Nucleic acid recovered from the isolates were amplified by RT-PCR and sequenced. Nucleotide and deduced amino acid sequences from the Argentine isolates were compared with 17 sequences available from the GenBank. Phylogenetic analysis revealed that the Argentine isolates grouped together in a definite cluster near European strains. Despite the greater genetic variability among ORF 5 from different isolates and strains of EAV, phylogenetic trees based on ORF 5 and 6 are similar. Both trees showed that virus sequences from America and Europe segregate into distinct clades based on sequence analysis of either ORF 5 or 6. This study constitutes the first characterization of Argentine EAV isolates.

Characterization of Pd-CeOx interaction on α-Al2O3 support Gigola, Carlos Eugenio; Moreno, Mario Sergio Jesus; Costilla, Ignacio Oscar; Sanchez, Miguel Dario The Pd-Ce interaction was studied over CeO2 (0.3-2.5 wt.%)-Pd (1 wt.%)/α-Al2O3 catalysts used in the reforming reaction of CH4 with CO2. The samples were characterized by using high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The activity and selectivity behavior was in good agreement with that of other supported metal catalysts (Ni and Pd) modified with different promoters. The preliminary results of HRTEM would indicate that the CeOx forms small crystallites around the Pd particle. The XPS analysis for the regions of Ce 3d and Pd 3d, gives an account of Ce being present mostly as Ce3+ and a high binding energy for Pd 3d5/2 (335.3 eV), an evidence of Pd-Ce chemical interaction. The Pd/Al XPS intensity ratios vs. the Pd average particle size, determined by TEM, show an excellent correlation for fresh and used catalyst. These results indicate that the diminution of the Pd/Al ratios was due to Pd sintering. Consequently, the small amounts of CeOx species do not cover the Pd particle, in agreement with the HRTEM results. The overall results stand for the promoter action mechanism of the CeOx for the reforming reaction with CO2.

The Lévy fractional Brownian motion family as a new paradigm in the modeling of turbulent wave-front phase Pérez, Darío Gabriel; Zunino, Luciano José; Garavaglia, Mario Jose In Perez et al. [J. Opt. Soc. Am. A 21 (10), 2004] we have given a general formalism to model the turbulent wave-front phase by using fractional Brownian motion processes. Moreover, it extends classical results to non- Kolmogorov turbulence: the Strehl ratio and the angle-of-arrival variance are shown to be dependent on the dynamic state of the turbulence. Nevertheless, this model has its drawbacks as it is unable of handling the stationarity of the phase increments over the full inertial range. The Levy fractional Brownian motion (LfBm) family is then introduced here in order to overcome this problem.

Competitiveness of a Bradyrhizobium sp. Strain in Soils Containing Indigenous Rhizobia Bogino, Pablo Cesar; Banchio, Erika; Bonfiglio, Carlos; Giordano, Walter Fabian The success of rhizobial inoculation on plant roots is often limited by several factors, including environmental conditions, the number of infective cells applied, the presence of competing indigenous (native) rhizobia, and the inoculation method. Many approaches have been taken to solve the problem of inoculant competition by naturalized populations of compatible rhizobia present in soil, but so far without a satisfactory solution. We used antibiotic resistance and molecular profiles as tools to find a reliable and accurate method for competitiveness assay between introduced Bradyrhizobium sp. strains and indigenous rhizobia strains that nodulate peanut in Argentina. The positional advantage of rhizobia soil population for nodulation was assessed using a laboratory model in which a rhizobial population is established in sterile vermiculite. We observed an increase in nodule number per plant and nodule occupancy for strains established in vermiculite. In field experiments, only 9% of total nodules were formed by bacteria inoculated by direct coating of seed, whereas 78% of nodules were formed by bacteria inoculated in the furrow at seeding. In each case, the other nodules were formed by indigenous strains or by both strains (inoculated and indigenous). These findings indicate a positional advantage of native rhizobia or in-furrow inoculated rhizobia for nodulation in peanut.

Time reversal mirror and perfect inverse filter in a microscopic model for sound propagation Calvo, Hernan Laureano; Danieli, Ernesto Pablo; Pastawski, Horacio Miguel Time reversal of quantum dynamics can be achieved by a global change of the Hamiltonian sign (a hasty Loschmidt daemon), as in the Loschmidt Echo experiments in NMR, or by a local but persistent procedure (a stubborn daemon) as in the time reversal mirror (TRM) used in ultrasound acoustics. While the first is limited by chaos and disorder, the last procedure seems to benefit from it. As a first step to quantify such stability we develop a procedure, the perfect inverse filter (PIF), that accounts for memory effects, and we apply it to a system of coupled oscillators. In order to ensure a numerical many-body dynamics intrinsically reversible, we develop an algorithm, the pair partitioning, based on the Trotter strategy used for quantum dynamics. We analyze situations where the PIF gives substantial improvements over the TRM.

Derived invariance of Hochschild–Mitchell (co)homology and one-point extensions Herscovich Ramoneda, Estanislao Benito; Solotar, Andrea Leonor In this article we prove derived invariance of Hochschild-Mitchell homology and cohomology and we extend to k-linear categories a result by Barot and Lenzing concerning derived equivalences and one-point extensions. We also prove the existence of a long exact sequence à la Happel and we give a generalization of this result which provides an alternative approach.

Caracterización de la zona de alteración Central II, bloque San Rafael, provincia de Mendoza; Characteristics of Central II alteration zone, San Rafael Massif, province of Mendoza Gargiulo, Maria Florencia; Rubinstein, Nora Alicia; Carpio, Francisco; Salvarredi, Julio. Se presenta el estudio petrográfico de las muestras de superficie correspondientes a la zona de alteración Central II, localizada en el Bloque San Rafael, provincia de Mendoza (34°54'56" S; 68°37'02" O). La misma está relacionada a la intrusión de un cuerpo hipabisal de composición riolítica alojado en una sucesión de rocas volcánicas y volcaniclásticas de la sección superior del Grupo Choiyoi. La zona de alteración está representada por sericitización generalizada a la que se sobreimponen brechas y venas silíceas, ocasionalmente con textura drusiforme y con bandas tapizadas por agregados diseminados de pirita y calcopirita subordinada, a las que acompaña escasa arsenopirita. Las brechas y venas silíceas conforman una faja de dirección ONO (azimut 290° - 300°) e inclinación vertical, en las que se han reconocido texturas de cuarzo hidrotermal de crecimiento primario, de recristalización y de reemplazo. Entre estas texturas se destacan las crustificaciones complejas, el bandeamiento coloforme y los pseudomorfos de cuarzo según calcita en enrejado, a las que se asocia la presencia de adularia con morfologías sub-rómbica, rómbica y pseudo-acicular. Este conjunto de texturas y morfologías permite establecer que se trata de un sistema epitermal de baja sulfuración con paleozonas de ebullición ascendente.; The goal of this paper is to present the petrographic study from outcrop samples of the Central II alteration zone. This area is located in the San Rafael Massif, province of Mendoza (34°54'56" S; 68°37'02" O) and is related to hypoabyssal rhyolitic bodies that intrude a volcanic-volcaniclastic sequence corresponding to the upper section of Choiyoi Group. The alteration zone is represented by pervasive sericitization overprinted by silicic breccias and veins with WNW trend (Az 290° - 300°) and vertical dip. Hydrothermal veins are mainly composed by quartz with primary growth, recrystalization and replacement textures with minor pyrite, chalcopyrite and scarce arsenopyrite. The combination of crustifiform - colloform silica banding, quartz pseudomorphs of bladed calcite and adularia with different morphologies (sub-rhombic, rhombic and pseudo-acicular) is a clear evidence of a low-sulfidation epithermal system with paleozones of upflow boiling.

Memory effects and peak effect in type II superconductors Pasquini, Gabriela; Luna, Diego Alejandro; Eismann, B.; Bettachini, Víctor; Bekeris, Victoria Isabel A large amount of experimental and theoretical work has been devoted to understand memory effects (ME) in the solid vortex lattice (VL) but has remained, however, controversial until now. In the vicinity of the anomaly known as the peak effect (PE) both the VL mobility and the measured critical current density are found to be dependent of the dynamical history of the sample, in both low Tc (LTS) and high Tc (HTS) superconductors. Experiments in YBa2Cu3O7 (YBCO) crystals have shown that the mobility of the VL increases after assisting the system with a symmetric AC field (or current) of moderated amplitude. On the other hand, after an asymmetric AC field assists vortices, the VL becomes less mobile. These features indicate that ME in these samples cannot be ascribed to an equilibration process, but probably are related to the organization of the lattice after nearest neighbor re-accommodation or induced plastic VL deformation. Recently, we have shown evidence that in YBCO the PE is a dynamic anomaly observed in the non-linear response, and is absent in the Labusch constant derived from the linear Campbell regime. However, this behavior seems not to be extensive to other systems as the traditional LTS NbSe2. In this work, the AC response in the PE region of NbSe2 and YBCO samples are presented and compared. Very salient differences both in the linear and non-linear response as well as in the ME characteristics indicate that a different physics governs the PE phenomena in each case. © 2007 Elsevier B.V. All rights reserved.

Phantom reflexes: Muscle contractions at a frequency not physically present in the input stimuli Manjarrez, Elías; Balenzuela, Pablo; García Ojalvo, Jordi; Vásquez, E.E.; Martínez, Lourdes; Flores, A.; Mirasso, Claudio R. In the motor system, the periodic stimulation of one Ia-afferent input produces reflex muscle contractions at the input frequency. However, we observed that when two Ia monosynaptic reflex-afferent inputs are involved the periodic muscle contractions may occur at a frequency physically not present in the afferent inputs even when these inputs are sub-threshold. How can the muscles respond with such phantom reflex contractions at a frequency physically absent in the sub-threshold Ia-afferent input stimuli? Here we provide an explanation for this phenomenon in the cat spinal cord, that we termed "ghost motor response". We recorded monosynaptic reflexes in the L7 ventral root, intracellular potentials in the motoneurons, and the associated muscular contractions elicited by stimulation of the lateral and medial gastrocnemius nerves. By stimulating with periodic pulses of sub-threshold intensities and distinct frequencies of 2 and 3 Hz the lateral and medial gastrocnemius nerves, respectively, we observed monosynaptic responses and phantom reflex muscle contractions occurring at the fundamental frequency (1 Hz), which was absent in the input stimuli. Thus we observed a reflex ghost motor response at a frequency not physically present in the inputs. We additionally studied the inharmonic case for sub-threshold stimuli and observed muscular contractions occurring at much lower frequencies, which were also conspicuously absent in the inputs. This is the first experimental evidence of a phantom reflex response in the nervous system. The observed behavior was modeled by numerical simulations of a pool of neurons subjected to two different input pulses.

CDW theoretical description of the single ionization of argon by positron and electron impact Otranto, Sebastián; Olson, Ronald E. In this work, we consider the single ionization of Ar by 200 eV positron and electron impact. The quantum mechanical continuum distorted wave (CDW) model is used in the one-active electron approximation. Parametrizations of Hartree-Fock potentials by Garvey et al. are used to represent the interaction of the light particles with the Ar + ion. The post collisional interaction (PCI) between the emitted electron and the receding projectile is naturally considered by the present model. Comparison with recent experimental data for very asymmetric geometries is made. The role of the PCI is studied by analyzing the differences in the angular distributions for positron and electron impact predicted by the CDW model and the first Born approximation.

Evolution of the properties of PtGe/Al2O3 reforming catalysts with Ge content Mariscal, Rafael; García Fierro, José Luis; Yori, Juan Carlos; Parera, Jose; Grau, Javier Mario The effect of the Pt/Ge atomic ratio on the catalytic activity of PtGe/Al2O3 catalysts used in n-heptane reforming was studied. The samples were prepared by the coimpregnation method on chlorinated alumina. The platinum content was 0.5 wt.%, and Ge-loading was varied to obtain Pt/Ge atomic ratios of 0.3, 0.7, 1.4, 2.1 and 3.5. Pt/Al2O3 and Ge/Al2O3 catalysts were also prepared as references. Characterization was carried out by temperature-programmed reduction (TPR), temperature-programmed desorption of ammonia (NH3-TPD), Fourier transform IR spectroscopy (FTIR) with CO as the probe molecule, X-ray photoelectron spectroscopy (XPS), cyclohexane (CH) dehydrogenation, and n-heptane reforming. The preparation method followed in this work revealed a decrease in the metallic activity of Pt due to the presence of Ge. The Ge2+ and Ge4+ species, after reduction at 500 °C, were detected on the surface of PtGe catalysts. The increase in the Ge content led to a decrease in hydrogenolysis activity and the formation of aromatics; an increase in the formation of isomers and cycloparaffins, and a reduction in the production of gas and in deactivation by coke, thereby improving catalyst stability. The results show that the maximum isoparaffin yield of all catalysts tested was obtained for a Ge-loading of 0.27 wt.% (Pt/Ge atomic ratio = 0.7). These changes in the performance of the PtGe catalysts may be attributed to the modifications occurring in the metallic and in the acid function of Pt/Al2O3 due to the introduction of Ge. The metallic catalytic activity of Pt is modified by the geometrical effect (dilution of Pt ensembles) and changes in the electronic properties of platinum. Ge addition produces a weakening of Pt/Al2O3 acid strength and an increase in the acid sites total density by the presence of Ge oxides.

2-Dimension from the topological viewpoint Barmak, Jonathan Ariel; Minian, Elias Gabriel In this paper we study the 2-dimension of a finite poset from the topological point of view. We use homotopy theory of finite topological spaces and the concept of a  beat point to improve the classical results on 2-dimension, giving a more complete answer to the problem of all possible 2-dimensions of  an n-point poset.

New antitumoral acetogenin “guanacone type” derivatives: isolation and bioactivity. Molecular dynamics simulation of diacetyl-guanacone Barrachina, Isabel; Royo, Inmaculada; Baldoni, Hector Armando; Chahboune, Nadia; Suvire, Fernando Daniel; DePedro, Nuria; Zafra Polo, M. Carmen; Bermejo, Almudena; El Aouad, Noureddine; Cabedo, Nuria; Saez, Jairo; Tormo, José R.; Enriz, Ricardo Daniel; Cortes, Diego We describe herein the isolation and semisynthesis of four acetogenin derivatives (1–4) as well as their ability to inhibit the mitochondrial respiratory chain and several tumor cell lines. In addition, four nanoseconds (ns) of MD simulation of compound 4, in a fully hydrated POPC bilayer, is reported.

Modelado de la extracción con hexano de molido de soja pretratado enzimáticamente; Modelling the hexane extraction of soya enzymatically pretreated grits Grasso, Florencia Verónica; Maroto, Beatriz Graciela; Camusso, Celso Clemente; Zaritzky, Noemi Elisabet En este trabajo se estudia la influencia de las variables de proceso que pueden tener efecto sobre el rendimiento de la extracción con hexano a partir de soja molida pretratada enzimáticamente. Se propone a partir de los resultados experimentales, un modelo matemático para el cálculo del rendimiento de la extracción. Los tests estadísticos utilizados para obtener este modelo demostraron que el rendimiento en aceite no depende del pH de la incubación enzimática mientras que si depende tanto de la temperatura como del tiempo de ataque enzimático sobre el molido de soja. El modelo ajustó satisfactoriamente los datos experimentales.; In this work, the influence of the variables which can affect oil extraction from soybean enzymatically pretreated grit using hexane, were studied. From the experimental results, a mathematical model for calculating the extraction yield was proposed. The statistical tests used to obtain this model showed that the yield does not depend on the enzymatic incubation pH but on the temperature and time of enzymatic treatment and on the interaction between time and temperature. The proposed model fit the experimental data well.

Evaluación de disfunción endotelial en pacientes con diabetes tipo 2; Dysfunction endothelial evaluation in type 2 diabetes patients Velarde, María Susana; Prado, María Mercedes; Carrizo, Teresita del Rosariio; Abregu, Adela Victoria; Sanchez, Sara Serafina del V. El objetivo de este trabajo fue estudiar moléculas involucradas en la activación endotelial, tales como la molécula de adhesión sE-Selectina (sE-S) y el péptido vasoconstrictor Endotelina-1 (ET-1) en individuos diabéticos tipo 2 y su asociación con otros factores de riesgo cardiovascular. Se estudiaron 62 pacientes diabéticos que se compararon con un grupo control. Las concentraciones de sE-S y ET-1 fueron significativamente mayores en los diabéticos que en los controles (sE-S: 90,6±26,2 ng/mL vs. 49,5±9,2 ng/mL, p<0,00001; ET-1: 11,3±3,7 vs. 7,7±0,5 pg/mL, p<0,001, respectivamente). Estas moléculas, en pacientes con índice de masa corporal (IMC) normal y aumentado, mostraron diferencias significativas (sE-S: 75,5±22,4 vs. 97,1±32,9 ng/mL, p< 0,05; ET-1: 8,4±2,4 vs. 14,1±4,9 pg/mL, p=0,001, respectivamente). No se encontraron diferencias entre individuos diabéticos normo e hipertensos, no fumadores y fumadores, ni normo e hipercolesterolémicos. El 81% de la población estudiada presentó un pobre control glucémico (HA1c>7%), siendo significativamente mayores los niveles de ET-1 en este grupo (p<0,01) no así para sE-S (p=0,74). Los resultados obtenidos muestran que los pacientes diabéticos presentan activación endotelial reflejada en los niveles elevados de sE-S y ET-1. El IMC aumentado y el pobre control glucémico incrementan la disfunción endotelial en estos pacientes.; The object of this work was to study molecules involved in endothelial activation, such as E-selectin (sE-S) and the vasoconstrictor peptide Endothelin-1 (ET-1) in Type 2 diabetes patients, and their relation with other cardiovascular risk factors. Sixty-two patients with diabetes were compared with matched controls. sE-S and ET-1 concentrations in diabetes patients were significantly elevated compared with controls (sE-S: 90.6±26.2 ng/mL vs 49.5±9.2 ng/mL, p<0.00001; ET-1: 11.3±3.7 vs 7.7±0.5 pg/mL, p<0.001, respectively). sE-S and ET-1 levels in diabetes patients with normal and increased body mass index showed significant differences (sE-S: 75.5±22.4 vs. 97.1±32.9 ng/mL, p<0.05; ET-1: 8.4±2.4 vs. 14.1±4.9 pg/mL, p=0.001 respectively). There were no significant differences in none of the molecules values between patients with or without hypertension, smokers or non-smokers, neither in diabetes patients with or without hypercholesterolemia. Eighty-one percent of the population with diabetes presented a poor glycemic control (HA1c>7%) and in these patients, ET-1 plasma levels were significantly increased (p<0.01), but not sE-S (p=0.74). These results show that obesity and a poor glycemic control increase the endothelial dysfunction in type 2 diabetes patients.

Time dependence of isotopic temperatures Barrañón, Armando; Dorso, Claudio Oscar; López, Jorge A. In this study the double isotope yield ratio thermometer, commonly used in heavy ion reactions, is put to the test in molecular dynamics simulations for a variety of nuclear reactions and energies. Comparing results to other estimates of the temperature and to experimental measurements, it is determined that the double isotope yield temperature indeed reflects the hot and dense phase of the reaction. Correlations between the double isotope yield temperature, the system size, beam energies, and collision times were investigated. © 2007 Elsevier B.V. All rights reserved.

Crop rotation and tillage systems as a proactive strategy in the control of peanut fungal soilborne diseases Vargas Gil, Silvina; Meriles, Jose Manuel; Haro Juarez, Ricardo Javier; Casini, Cristiano; March, Guillermo Juan Soil management practices can affect the population dynamics of soil microbial communities. Cultural practices can be adequately combined to benefit natural populations of microorganisms that may have a role in biological control (actinomycetes, Trichoderma spp., and Gliocladium spp.), thus contributing to the management of peanut fungal soilborne diseases in a sustainable manner within ecological boundaries. During six agricultural cycles, rhizosphere soil samples were taken from a field subjected to crop rotation (soybean, peanut, and maize), peanut being under two tillage systems (no till, reduced tillage) with the aim of quantifying populations of soil microorganisms. The incidence of diseases caused by soilborne fungi in peanut was determined at harvest. The highest amount of actinomycetes, Trichoderma spp., and Gliocladium spp. were recorded when maize was the preceding crop. Regarding tillage systems, the populations of the three groups of microorganisms were higher in peanut under no tillage than under reduced tillage. Under these conditions, the lowest incidence of peanut blight (Sclerotinia minor) and root rot (strains of Fusarium solani) was observed, suggesting a possible natural control of peanut soilborne pathogens. The quantification of actinomycetes, Trichoderma spp., and Gliocladium spp. was used as a tool to explore the impacts of different management systems on microbial groups that may be involved in the biological control of soilborne diseases, with the aim of combining those practices that improve native populations of possible beneficial microorganisms. This manipulation can provide sustainable management strategies in the control of soilborne diseases, avoiding the use of artificial inoculations of microorganisms, and reducing agrochemical application.

Comparative studies of loblolly pine biodegradation and enzyme production by Argentinean white rot fungi focused on biopulping processes Levin, Laura Noemí; Villalba, Laura; Da Re, Cristina Verónica; Forchiassin, Flavia; Papinutti, Víctor Leandro The ability of eight white rot fungi: Coriolopsis rigida, Coriolus versicolor var. antarcticus, Peniophora sp., Phanerochaete sordida, Pycnoporus sanguineus, Steccherinum sp., Trametes elegans and Trametes villosa to selectively delignify loblolly pine (Pinus taeda) chips was studied. They were selected among 34 basidiomycetes from Argentina because of their capacity to decolorize Poly R-478 and Azure B. Fungal pretreatment caused changes in wood chemical composition as well as in physical structure. The present study allowed the identification of a new strain, potentially a candidate for use in softwoods biopulping processes. Results showed that P. sanguineus was able to reduce lignin content in 11% in 14 days of treatment, but also that P. taeda wood suffered notable structural changes of lignin and hemicelluloses during the treatment, as revealed from 13C CP-MAS NMR spectra. An increase of 15% in porosity of decayed wood confirmed physical changes due to fungal attack.