Theory of braided Hopf crossed products Guccione, Jorge Alberto; Guccione, Juan Jose We define a type of crossed product over braided Hopf algebras, which generalizes the ones introduced by Blattner, Cohen and Montgomery and Doi and Takeuchi, and we study some of its properties. For instance, we prove a Maschke´s Theorem for these new crossed products and under suitable hypothesis we construct a natural Morita context which extends the one obtained by Cohen, Fischman and Montgomery.

On the composition of the integral and derivative operators of functional order Hartzstein, Silvia Inés; Viviani, Beatriz Eleonora In this work we show that the composition of the integral and derivative operators of order phi, T_phi = D_phi◦I_phi, is a singular integral operator.This result in addition with the results obtained in [HV2] of boundedness of I_phi and D_phi or the T1-theorems proved in [HV1] yield the fact that T_phi is a Calderón-Zygmund operator bounded on the generalized Besov and Triebel-Lizorkin spaces of functional order.

Bulk hydrosilylation reaction of poly(dimethylsiloxane) chains catalyzed by a platinum salt: Effect of the initial concentration of reactive groups on the final extent of reaction Roth, Leandro E.; Vallés, Enrique M.; Villar, Marcelo Armando Model silicone networks obtained by curing linear poly(dimethylsiloxane) (PDMS) chains with end-vinyl groups, (B2), with a polyfunctional silane-terminated crosslinker of functionality f, (Af), through a hydrosilylation reaction have been widely used. In these networks, the principal characteristics of their ultimate molecular structure are strongly affected by the final extent of reaction reached during the crosslinking reaction. This work analyzes the effect of the initial concentration of the reactive end groups on the maximum attainable extent of reaction under normal bulk crosslinking conditions. This was accomplished by examining the reaction between linear B2 PDMS chains with difunctional and trifunctional silanes. The experimental results were fitted by an exponential equation to have an empirical equation able to predict the maximum extent of reaction to be obtained as a function of the initial concentration of reactive groups. Molecular parameters relevant to this study, such as the degree of polymerization, the weight-average molecular weight for the A2 + B2 system, or the weight fraction of solubles for the A3 + B2 system, were calculated with a mean field theory (recursive approach).

Intestinal passive absorption of hydrosoluble compounds by sparrows: effect of molecular size and luminal nutrients Chediack, Juan Gabriel; Caviedes Vidal, Enrique Juan Raul; Fasulo, Sara Veronica; Yamin, L. J.; Karasov, William We tested predictions that: (1) absorption of water-soluble probes decreases with increasing molecular size, consistent with movement through effective pores in epithelia, and (2) absorption of probes is enhanced when measured in the presence of luminal nutrients, as predicted for paracellular solvent drag. Probes (L-arabinose, L-rhamnose, perseitol, lactulose; MW 150.1–342.3 Da) were gavaged in nonanesthetized House sparrows (Passer domesticus), or injected into the pectoralis, and serially measured in plasma. Bioavailability was calculated as F=AUC by gavage/AUC by injection, where AUC is the area under the curve of plasma probe concentration vs. time. Consistent with predictions, F declined with probe size by 75% from the smallest to the largest probe, and absorption of probes increased by 40% in the presence of luminal glucose or food compared to a mannitol control. Absorption of water-soluble probes by sparrows is much higher than in humans, which is much higher than in rats. These differences seem mainly attributable to differences in paracellular solvent flux and less to differences in effective paracellular pore size.

The two isoforms of the cAMP-dependent protein kinase catalytic subunit are involved in the control of dimorphism in the human fungal pathogen Candida albicans Cloutier, Monikca; Castilla Lozano, Maria del Rocio; Bolduc, Nathalie; Zelada, Alicia Mercedes; Martineau, Philippe; Bouillon, Marlène; Magee, Beatrice B.; Di Bernardo, Maria Susana; Giasson, Luc; Cantore, Maria Leonor We have cloned the Candida albicans TPK2 gene encoding a cAMP-dependent protein kinase (PKA) catalytic subunit and generated a tpk2 homozygous null mutant to assess its ability to germinate in liquid media. N-acetylglucosamine (GlcNAc)-induced germ-tube formation was attenuated in the tpk2 strain and enhanced by compounds that are known to increase the PKA activity in situ. Germination was completely blocked in the presence of the myristoylated derivative of the heat-stable PKA inhibitor (MyrPKI). These results indicate that TPK1 acts positively in regulating the morphogenetic transition in C. albicans in the absence of the TPK2 gene. We were able to identify an mRNA from this second form of PKA in both wild-type and tpk2 null mutant cells. We found that PKA activity measured in the mutant lacking the TPK2 gene was about 10% of that displayed by the wild-type. The finding that the germinative response of tpk2 null mutant to serum was severely diminished at low serum concentrations indicates that the level of PKA is an important determinant of filamentous growth at low serum concentrations. The extent of germination attained at higher serum concentrations (5%) was similar in the wild-type and in the tpk2 null mutant strains suggesting that under these conditions germination was triggered through a PKA-independent pathway.

Imaging study of NGC 3372, the Carina nebula -I. UBVRIJHK photometry of Tr 14, Tr 15, Tr 16 and Car I Tapia, Mauricio Andres; Roth, Miguel; Vazquez, Ruben Angel; Feinstein, Alejandro We present the results of a large-scale imaging photometric study of the stellar population in the northern part of NGC 3372 in the UBVRIJHK bands with a wavelength coverage from 0.33 to 2.5 μm. The observations were made at Las Campanas Observatory. The optical CCD mosaics cover an area approximately of 32 × 22 arcmin2 centred between the Tr 14 and Tr 16 clusters. The survey was extended to cover 12 × 12 arcmin2 at the location of Tr 15. Near-infrared NICMOS3 mosaics covering the areas occupied by these clusters were obtained in the JHK photometric bands. By means of star counts in V, the centres and sizes of each cluster were redetermined yielding: Tr 14 (r = 264 arcsec), Tr 15 (r = 320 arcsec) and Tr 16 (r = 320 arcsec). It was confirmed that Cr 232 is not a true cluster. Multicolour optical photometry was obtained for 4152 stars. Two colour and colour-magnitude diagrams are presented and analysed for each individual cluster and compared to those of the field. We confirm the widespread variations in the dust density and also in the dust size distribution leading to widely different values of AV and reddening laws towards Tr 14 and Tr 16. No spatial patterns were found for these variations. Spectroscopic parallaxes were computed and the results are consistent with all three clusters being at a similar distance from the Sun (〈d〉 = 2.7 kpc) but the data have shown very large scatter in both AV and d. Analyses of the extinction-corrected colour-magnitude diagrams suggest ages between 3 and 60 million years for the stars in Tr 15 and between less than 1 and 6 million years for Tr 14 and Tr 16. A small number of infrared-excess stars were found in Tr 16 and Tr 14 but not in Tr 15. The distribution of stars in Tr 14 seen in the near-infrared suggests that this cluster is partially embedded in a molecular cloud. This molecular cloud extends towards the west reaching its highest density, marked by a CO peak emission, some three arcmin to the south-west of the nucleus of Tr 14. The rich ultraviolet field created by the Tr 14 stars ionizes most of the visible H II region in its vicinity and most of the radio H II region Car I. Evidence is found of ionization fronts leading into the molecular cloud, which appears to be 'wrapping' the Tr 14 cluster. Deep JHK images of the Car I region reveal the presence of an embedded stellar population illuminating a large infrared reflection nebula. It includes at least one O9-B0 star associated with an ultracompact H II region. Nebulous 2.2 μm emission from three of the mid-infrared sources in the Tr 14 region is also found.

Fouling behaviour of polyethersulfone UF membranes made with different PVP Marchese, Jose; Ponce, Mariela Leticia; Ochoa, Nelio Ariel; Prádanos, Pedro; Palacio, Laura; Hernández, Antonio Several polyethersulfone (PES) ultrafiltration membranes have been made with small quantities of polyvinyl-pyrrolidone (PVP) of different molecular weights to increase the permeability without a significant reduction in selectivity. The corresponding fouling mechanism and subsequent structural modifications have been analyzed when in contact with bovine serum albumin (BSA) and DL-histidine (DLH). It has been shown that according to the relative sizes of solute and pores of the membranes: BSA fouls the three membranes externally whereas DLH fouls them internally. Moreover, BSA fouls the non-PVP membranes faster than DLH fouls them slower, according to the action of hydrophobic and electrostatic forces acting at the working pH (4.9). The changes in structure, remaining after water rinsing, is quite similar for the three membranes and both the solutes, as obtained by a r etention test of adequate polyethylene glycols (PEGs).

Transtegumental diffusion of benzimidazole anthelmintics into Moniezia benedeni: correlation with their octanol–water partition coefficients Mottier, Maria de Lourdes; Alvarez, Luis Ignacio; Pis, Ma. Alejandra; Lanusse, Carlos Edmundo The experiments described here report on the correlation between the ex vivo diffusion of different benzimidazole (BZD) anthelmintics into the cestode parasite Moniezia benedeni, and their octanol–water partition coefficients (P.C.). The characterisation of the drug diffusion process into target parasites is relevant to understand the mechanism of drug penetration and the pharmacological activity of anthelmintic drugs. Specimens of the tapeworm M. benedeni, used as a helminth parasite model, were obtained from untreated cattle killed at the local abattoir. The collected parasites were incubated (5–210 min) with either fenbendazole (FBZ),albendazole (ABZ), ricobendazole (RBZ), oxfendazole (OFZ), mebendazole (MBZ), oxibendazole (OBZ), or thiabendazole (TBZ), in a Kreb’s Ringer Tris buffer medium at a final concentration of 5 nmol/ml. After the incubation time elapsed, samples of parasite material were chemically extracted and prepared for high performance liquid chromatography (HPLC) analysis to measure drug/metabolite concentrations. Additionally, the octanol–water P.C. for each molecule was estimated as an indicator of drug lipophilicity,using reversed phase HPLC analysis. All the incubated drugs were recovered from the tapeworms as early as 5 min post incubation. There was a high correlation (r ¼ 0:87) between drug lipophilicity, expressed as octanol–water P.C. (Log P), and drug availability within the parasite. The most lipophilic BZD compounds (FBZ, ABZ, and MBZ), with P.C. values higher than 3.7, were measured at significative higher concentrations within the tapeworm compared to those drugs with the lowest P.C. values. Considering the results from the current and previous studies, it is clear that passive diffusion is a major mechanism of BZD penetration into cestode parasites, where lipid solubility is a determinant factor influencing the diffusion of these anthelmintic molecules through the parasite tegument.

Simulation of an Industrial Packed Column for Reactive Absorption of CO2 Gómez, C.; Borio, Daniel Oscar; Schbib, Noemi Susana − The steady-state simulation of a reactive absorption column is presented. The absorber is used in a large-scale ammonia plant to remove CO2 from the process gas stream. To enhance the absorption process, high pressures and low temperatures are commonly used (T = 45-80 °C, P = 30-40 bar). At the outlet of the absorber, the CO2 content in the process gas must be reduced to less than 500 ppm (dry basis) to avoid an excessive temperature rise in the methanation reactor (downstream of the absorption section). To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory is considered. The heat effects are taken into account. The behaviour of different process variables for a reference operating condition is analyzed. The influence of changes in some operating variables is evaluated.

On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma-optical emission spectrometry Ortega, Claudia Alicia; Cerutti, Estela Soledad; Olsina, Roberto Antonio; Silva, María Fernanda; Martinez, Luis Dante An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30°C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L-1 nitric acid at a flow rate of 1.5 mL min -1, directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 μg L-1. The precision for 10 replicate determinations at the 2.0 μg L-1 Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 μg L-1. The method was successfully applied to the determination of dysprosium in urine.

Cohomology of split algebras and of trivial extensions Cibils, Claude; Marcos, Eduardo; Redondo, Maria Julia; Solotar, Andrea Leonor We consider associative algebras λ over a field provided with a direct sum decomposition of a two-sided ideal M and a sub-algebra A - examples are provided by trivial extensions or triangular type matrix algebras. In this relative and split setting we describe a long exact sequence computing the Hochschild cohomology of λ. We study the connecting homomorphism using the cup-product and we infer several results, in particular the first Hochschild cohomology group of a trivial extension never vanishes.

Report on the 1st International Workshop of the IUGS Lower Cretaceous Ammonite Working Group, the 'Kilian Group' (Lyon, 11 July 2002) Hoedemaeker, Philip J.; Reboulet, Stéphane; Aguirre-Urreta, Maria Beatriz; Alsen, Peter; Aoutem, Mohamed; Atrops, François; Barragan, Ricardo; González Arreola, Celestina; Klein, Jaap; Lukeneder, Alexander; Ploch, Isabela; Raisossadat, Seyed Naser; Rawson, Peter F.; Ropolo, Pierre; Vasícek, Zdenek; Vermeulen, Jean; Wippich, Max G. E. The Lower Cretaceous Ammonite Working Group forms part of the IUGS Subcommission on Cretaceous Stratigraphy (Peter Rawson, chair) and is the successor of the Lower Cretaceous Cephalopod Team that formed part of IGCP Projects 262 and 362 respectively. The latter team had organized five Workshops (Klein & Hoedemaeker, 1999;Hoedemaeker & Rawson, 2000) and this is the first workshop under the new IUGS umbrella, which was organized by Stéphane Reboulet (Université de Lyon 1) directly after the 3rd French Symposium on Stratigraphy (Lyon, 8–10 July 2002). The workshop was attended by 18 members from 13 countries. The attendants agreed to call the group the ‘Kilian Group' after the famous French palaeontologist W. Kilian.

A prothrombin activator from Bothrops erythromelas (jararaca-da-seca) snake venom: characterization and molecular cloning Silva, Márcia B.; Schattner, Mirta Ana; Ramos, Celso R. R.; Junqueira de Azevedo, Inácio L. M.; Guarnieri, Míriam C.; Lazzari, María Ángela; Sampaio, Claudio A. M.; Pozner, Roberto Gabriel; Ventura, Janaina S.; Ho, Paulo L.; Chudzinski Tavassi, Ana M. A novel prothrombin activator enzyme, which we have named 'berythractivase', was isolated from Bothrops erythromelas (jararaca-da-seca) snake venom. Berythractivase was purified by a single cation-exchange-chromatography step on a Resource S (Amersham Biosciences) column. The overall purification (31-fold) indicates that berythractivase comprises about 5% of the crude venom. It is a single-chain protein with a molecular mass of 78 kDa. SDS/PAGE of prothrombin after activation by berythractivase showed fragment patterns similar to those generated by group A prothrombin activators, which convert prothrombin into meizothrombin, independent of the prothrombinase complex. Chelating agents, such as EDTA and o-phenanthroline, rapidly inhibited the enzymic activity of berythractivase, like a typical metalloproteinase. Human fibrinogen Aα-chain was slowly digested only after longer incubation with berythractivase, and no effect on the β- or γ-chains was observed. Berythractivase was also capable of triggering endothelial proinfiammatory and procoagulant cell responses, von Willebrand factor was released, and the surface expression of both intracellular adhesion molecule-1 and E-selectin was up-regulated by berythractivase in cultured human umbilical-vein endothelial cells. The complete berythractivase cDNA was cloned from a B. erythromelas venom-gland cDNA library. The cDNA sequence possesses 2330 bp and encodes a preproprotein with significant sequence similarity to many other mature metalloproteinases reported from snake venoms. Berythractivase contains metalloproteinase, desintegrin-like and cysteine-rich domains. However, berythractivase did not elicit any haemorrhagic response. These results show that, although the primary structure of berythractivase is related to that of snake-venom haemorrhagic metalloproteinases and functionally similar to group A prothrombin activators, it is a prothrombin activator devoid of haemorrhagic activity. This is a feature not observed for most of the snake venom metalloproteinases, including the group A prothrombin activators.

Propagator matrices as matrices of power's series. II. It's relationship with HF's stability problem and alternative solutions Gómez, Carlos Anselmo; Provasi, Patricio Federico; Aucar, Gustavo Adolfo Some non-singlet quasi-instabilities (QIs) cases that arise in the calculation of NMR-Jparameters are analyzed within response theory. The relationship between ‘very close to zero’ eigenvalues of the principal propagator and the rate of convergency for specific coupling pathways is shown by a power series implemented to calculate the principal propagator matrix. A natural criterion for the analysis of the stability problem emerges from that series. This is more general and accurate compared with previous proposals. Its relationship with π-type molecular orbitals is given. We present an alternative scheme to minimize the effects of non-singlet QIs in such a way that the NMR-J parameters become close to the best theoretical calculations for H2CX (X=CH2, NH and O).

Arginine metabolic pathways involved in the modulation of tumor‐induced angiogenesis by macrophages Davel, Lilia Elena; Jasnis, Maria Adela; de la Torre, Eulalia; Gotoh, Tomomi; Diament, Miriam; Magenta, Gabriela Viviana; Sacerdote de Lustig, Eugenia; Sales, María Elena Neovascularization, an essential step for tumor progression and metastasis development, can be modulated by the presence of macrophages (Mps) in the tumor microenvironment. The ability of Mps to regulate the angiogenicity of the LMM3 tumor cell line was studied. Peritoneal Mps from LMM3 tumor‐bearing mice (TMps) potentiate in vivo LMM3 angiogenicity. These results were confirmed by CD31 immunoblotting assays. The activity of TMps depended on nitric oxide synthase (NOS) and arginase (A) activity. By immunoblotting we evidenced that AI and AII isoforms were up‐regulated in TMps while the inducible and neuronal NOS isoforms were highly expressed in normal Mps. TMps might positively modulate tumor growth by stimulating angiogenic cascade mainly through polyamine synthesis.

Body mass and habitat correlates of song structure in a primitive group of birds Bertelli, Sara Beatriz; Tubaro, Pablo Luis We assessed relationships between acoustic frequency, body mass, and habitat in tinamous. This monophyletic group of primitive birds comprises 47 ground dwelling species whose habitats range from dense humid forest to open grasslands.The relationship between frequency and body mass was found to be negative, while the songs of open habitat species exhibited higher frequencies and a wider bandwidth than the closed-habitat ones. Residual variation in song frequency, after controlling for the effect of body mass and phylogeny, tends to differ among habitats. However, a statistical test of this pattern was not possible because of the existence of only five pairs of sister species differing in habitat. In spite of this, positive contrasts of bandwidth were associated with positive contrasts of habitat, confirming that songs of open-habitat species have a wider bandwidth than those of their more closed habitat relatives.

How reliable could economic Hartree-Fock computations be in studying large, folded peptides? A comparative HF and DFT case study on N- and C-protected aspartic acid Koo, Joseph C.P.; Lam, Janice S.W.; Salpietro, Salvatore J.; Chass, Gregory A.; Enriz, Ricardo Daniel; Torday, Ladislaus L.; Varro, Andras; Papp, Julius Gy. In this study, potential energy hypersurfaces have been generated and analyzed for each of the nine possible backbone (BB) conformations for both the endo and exo forms of N-acetyl-L-aspartic acid N′-methylamide. Ab initio calculations were carried out at RHF/3-21G, RHF/6-31G(d), and B3LYP/6-31G(d) levels for all backbone conformations. The relative energies, as well as stabilization energies exerted by the sidechain (SC) on the backbone, were calculated for all stable conformers. All sidechain-sidechain (HO···O=C), backbone-backbone (N-H⋯O=C), and sidechain-backbone (N-H···O=C; N-H···OH) hydrogen bond interactions were analyzed. The appearance of the traditionally absent αL and εL conformers may be recognized as special geometric orientation which the aspartyl residue manifests during peptide folding or ligand docking in a receptor that contains aspartic acids in its ligand recognition sites. At all three levels of theory, there exists a trend between the hydrogen bond distance and ring size. In addition, strikingly high correlations between the torsional angles (R2 = 0.9937 for RHF/6-31G(d) versus RHF/3-21G; R2 = 0.9967 for B3LYP/6-31G(d) versus RHF/6-31G(d); R2 = 0.9914 for B3LYP/6-31G(d) versus RHF/3-21G) and between the ΔE values in kcal/mol (R2 = 0.9424 for RHF/6-31G(d) versus RHF/3-21G; R2 = 0.9108 for B3LYP/6-31G(d) versus RHF/6-31G(d); R2 = 0.9434 B3LYP/6-31G(d) versus RHF/3-21G) found at the different ab initio levels suggest that calculations carried out at the lower levels (i.e. at RHF/3-21G) are still significant.

Orobothriurus atiquipa, a new bothriurid species (Scorpiones) from Lomas in southern Perú Ochoa, José Antonio; Acosta, Luis Eduardo Orobothriurus atiquipa new species (Scorpiones, Bothriuridae) from Lomas formations in the coastal desert of southern Perú is described and illustrated. This species belongs to the alticola species-group, and within the group, it is closely related to O. alticola (Pocock), O. paessleri (Kraepelin) and O. curvidigitus (Kraepelin). The spine formula (4 + 3) on tarsi III–IV is probably an autapomorphy for the new species. Some features of the habitat (the Lomas formation are green isolates in the coastal desert), as well as a distribution map are provided.

Papel del calcio y de la vitamina D en la salud ósea (Parte I) Sánchez, A.; Puche, R.; Zeni, Susana Noemi; Oliveri, María Beatriz; Galich, Ana María; Maffei, L.; Plantalech, L; Poudes, G.; Bregni, Carlos La osteoporosis, definida como una baja masa ósea y alteraciones de la microarquitectura del hueso que predisponen a las fracturas, es una enfermedad que asume características de pandemia y cuya prevalencia crecerá notoriamente en las próximas décadas en todo el mundo, pero sobre todo en Asia y América Latina. Si bien el desarrollo y el mantenimiento de una masa ósea normal dependen en un 70% de factores genéticos, los factores ambientales (como el ejercicio y la nutrición) son de gran importancia, y pueden modificarse favorablemente a nivel poblacional con apropiadas medidas educativas y culturales. Esta revisión se propone pasar revista al metabolismo del calcio y presentar la evidencia disponible sobre el papel que este nutriente (y la vitamina D, crucial para su correcta disponibilidad) tiene en el desarrollo y mantenimiento de un esqueleto sano; sobre la importancia fisiopatológica de la carencia crónica de calcio en el desarrollo de osteopenia en niños, jóvenes, adultos y viejos; y sobre el efecto beneficioso de la suplementación con calcio (y, a veces, de vitamina D) en la prevención y el tratamiento de la osteoporosis.

Una metáfora del vínculo vasallático: El Libro del Buen Amor Rígano, Mariela Elizabeth El objetivo de este trabajo es analizar el desarrollo metafórico de la relación vasallo-señor en el Libro del Buen Amor. El texto presenta, bajo la apariencia de este vínculo, a) la relación entre los seres humanos y la divinidad, sea esta pagana o cristiana, b) entre diversos animales entre sí y, finalmente, c) entre la personificación de costumbres cristianas (Carnal y Cuaresma) y distintos animales. Consideramos, entonces, que puede resultar particularmente interesante un estudio sobre el empleo de los elementos lingüísticos y paralingüísticos como recurso para caracterizar a los diferentes personajes y sus relaciones jerárquicas, puesto que podría ser un indicador de la difusión que este sistema habría alcanzado en ese momento histórico.Este trabajo se enmarca dentro de los lineamientos de la sociolingüística histórica.; The objective of this paper is to analyse the terms of address, the lexicon and the paralinguistic elements that are used in the Libro del Buen Amor (XIV c.) to present metaphorical the tie between beings of different hierarchy like the relationship between a vassal and a lord. This type of metaphors could be a indicator of the diffusion of the courtesy system in this century.