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.

Stylized Facts of the Gross National Product of Argentina: 1875 - 1999 Abril, Juan Carlos; Blanco, Maria Beatriz The stylized facts of macroeconomic time series can be presented by fitting structural time series models. Within this framework, we study the behaviour of the gross national product of Argentina in the long run and provide a method for modelling this behaviour, which in turn is equivalent to establishing the stylized facts associated with these time series. We analyse the annual data of the gross national product and the gross national product per capita of Argentina from 1875 to 1999. The study of these variables allows, among other things, to know the changes that have been taking place in the economy. The evolution of these variables in time tells us, roughly, if there was progress or not.

Foraging grounds of southern giant petrels (Macronectes giganteus) on the Patagonian shelf Quintana, Flavio Roberto; Dell'arciprete, Olga Patricia During the 1999 and 2000 breeding seasons we used satellite telemetry to track the foraging movements of four southern giant petrels (Macronectes giganteus) nesting on an island off the Argentine coast (45°08′, 66°03′). Three of the four individuals foraged east/southeast of the colony, over the middle continental shelf and the shelf break, between 43° and 51°S. The fourth individual remained in coastal areas to the south and lost the device after 15.5 days at sea. The maximum linear distance from the nest reached during a single foraging trip was 552 km. All birds were able to fly more than 400 km in 1 day, with a maximum of 513 km recorded. The maximum total distance covered in a single foraging trip was 2,540 km. Findings of this study emphasise the importance of the Patagonian continental shelf as foraging grounds for top predators in the South Atlantic Ocean.

Nucleotide sequence of the upstream regulatory region of BoLA-DRB Ripoli, María Verónica; Diaz, Silvina; Peral Garcia, Pilar; Giovambattista, Guillermo The sequence of the proximal upstream regulatory region (URR) of the bovine DRB genes was amplified using oligonucleotide primers designed from the consensus among DRB sequences from different species. The obtained DNA sequence was 234 bp long and composed of highly conserved sequence motifs, showing the same organization as the HLA-DRB, H2-IAb, H2-IEb and ELA-DRB genes. In this paper we report the sequence of the proximal upstream regulatory region (URR) of the bovine DRB genes. These are the first sequence data on the upstream regulatory regions of MHC class II genes in cattle. The reverse oligonucleotide primer (5′-GAGAAATA-CAGACACACCATGC-3′) was designed from the consensus among DRB sequences from different species: BoLA-DRB (accession numbers U77067-68, U78548 and D45357), SLA-DRB (M55165-6), HLA-DRB (S72812 and L07838-40), H2-IEb and H2-IAb (X86151-6). As a forward primer we used the oligonucleotide proposed by Turco et al. (1990) (5′-TGTTTCAGAAAAGGACCTTC-3′), which was designed from the consensus among HLA-DRB sequences corresponding to the promoter region of the DRB genes. A polymerase chain reaction (PCR) was carried out in a total volume of 25 μl comprising 2.5 mM MgCl2 Tris-HCl (pH = 8.4), 50 mM KCl, 100 μM of each dNTP, 0.5 μM of each primer, 1.0 unit Taq polymerase (Gibco BRL, Life-Technologies, Grand Island, NY) and 50-100 ng DNA template. The genomic DNA was extracted from whole blood from one animal of the Saavedreño Creole breed. The amplification profile consisted of 1 min at 94°C, followed by 30 cycles of 45 s at 94°C, 45 s at 55°C and 45 s at 72°C, with a final extension of 3 min at 72°C. The amplification products were cloned into a dT-tailed pGEM-T easy vector (Promega, Madison, WI), and three clones of each PCR product were sequenced on an Applied Biosystems 377 automated sequencer (Bio-Resource Center, Cornell University, Ithaca, NY), using a T7 universal primer. All the sequenced clones exhibited 100% sequence similarity to each other. The nucleotide sequence of the proximal upstream control region of the BoLA-DRB genes (GenBank accession number AY040327) was 234 bp long and composed of highly conserved sequence motifs that included, from the 5′ to the 3′ direction, W, X, Y, CCAAT and TATA-like boxes (Fig. 1), showing the same organization of the conserved regulatory elements as the HLA-DRB, H2-IAb, H2-IEb and ELA-DRB genes (e.g. Louis et al., 1993, 1994; Singal et al., 1993; Singal & Qiu, 1994). Furthermore, the BoLA-DRB URR nucleotide sequence had higher identity with HLA-DRB sequences than with HLA-DQB sequences (data not shown). This suggests that the sequence AY040327 corresponds to a BoLA-DRB promoter. However, we are still unable to assign this sequence to a specific BoLA-DRB gene, as at least three BoLA-DRB genes have been reported to exist (Andersson et al., 1986; Muggli-Cocket & Stone, 1988). BoLA-DRB3 is the most expressed DRB gene in cattle, while DRB1 is expressed at a low level and DRB2 is a pseudogene (Burke et al., 1991).

The Crassispora kosankei-Cystoptychus azcuyi palynozone of the Upper Carboniferous Tupambi Formation, Tarija Basin, northern Argentina Di Pasquo Lartigue, Maria Well-preserved and diverse palynomorph assemblages were recovered from surface and core samples from the middle to upper section of the Tupambi Formation. The latter is the basal unit of the Machareti Group (Upper Carboniferous) of the Tarija Basin, northern Argentina. Assemblages are composed of trilete miospores, one hilate species, monosaccate pollen grains (one species striated), one praecolpate species and green algae (Botryococcus). Two key species are Cystoptychus azcuyi sp. nov. and Crassispora kosankei (Potonié and Kremp) Bharadwaj emend. Smith and Butterworth enable definition of the first palynozone for this basin. The age, as well as the biostratigraphic and paleogeographic significance of the palynoflora is discussed.

Palynological zonation of the Lajas Formation (Middle Jurassic) of the Neuquén Basin, Argentina; Zonación palonológica de la Formación Lajas (Jurásico Medio), Cuenca Neuquina Martinez, Marcelo Adrian En este trabajo es presentada una nueva zonación palinológica para el Jurásico Medio del sector sur de la Cuenca Neuquina, con dos zonas y ocho subzonas creadas en base a esporomorfos y microplanton asociado, con un rango de edad que abarca desde el Aaleniano tardío hasta el Caloviano temprano. La zonación es correlacionada con zonaciones palinológicas previas de la mencionada cuenca. Se menciona el contenido macropaleontológico (principalmente amonites) y micropaleontológico (frecuencias relativas de taxones y grupos supragenéricos); A new palynological zonation for the Middle Jurassic of the southern part of the Neuquén Basin is presented. Two zones and eight subzones based on sporomorphs and associated microplankton of late Aalenian to early Callovian age are defined. These zones are correlated with previous palynological zonations in the Neuquén Basin. The macropaleontologic (mainly ammonites) and micropaleontologic content (relative frequencies of taxa and suprageneric groups) of each depositional sequence previously identified in the study area by other workers are given

Estimation of the plain high-cycle fatigue propagation resistance in steels Chapetti, Mirco Daniel In this work a method to estimate the high cyclic fatigue propagation life of steel specimens under constant loading is presented. This method is based in experimental evidence that the fatigue limit represents the threshold stress for the propagation of nucleated cracks, so that both the fatigue limit and the fatigue resistance depend on the effective resistance of the microstructural barriers that have to be overcome by the nucleated cracks. It is proposed also, that in those cases where the number of cycles that is necessary for the nucleation of the cracks can be neglected, the fatigue crack propagation life can be taken as an estimation of the total fatigue life. The high cycle fatigue propagation life of a structural steel of the type JIS 10C is estimated.

Brief commentary Schattner, Mirta Ana; Lazzari, María Ángela Recently, Tibbles et al. [1] reported that thrombopoietin (TPO) was capable of inducing P-selectin expression independently of calcium movements or platelet aggregation. They also found that leukocyte– platelet aggregates occurred after TPO cell stimulation most probably mediated by P-selection expression. Although they stated that they described a novel role for TPO in platelet function and platelet–leukocyte interactions both activities have been previously described by severalgroups [2–6]. Most of the studies showed that although TPO was not able to induce platelet activation alone it synergized platelet responses, including P-selectin expression, triggered by different agonists.

Reforma a la gestión educativa e identidad profesional de los docentes en Argentina: Estudio de un caso; Educational management reform and professional teacher identity in Argentina: A case study Freytes Frey, Ada Cora Dentro de la reforma educativa argentina, el 3° ciclo de la Educación General Básica (EGB) constituye un aspecto central, ya que plantea importantes quiebres con respecto a la estructura anterior. Este ciclo está integrado por los antiguos 7° grado de la escuela primaria y 1° y 2° año de la secundaria, por lo que implica la convivencia de dos culturas profesionales diferentes: la de los maestros y la de los profesores. A esto se suma la reformulación del rol docente que impulsa la reforma. En este trabajo, se analiza la incidencia de estos procesos en la constitución de la identidad profesional de los docentes del 3° ciclo en la provincia de Buenos Aires. Esto supone una indagación en diversos planos: a) las interpelaciones acerca de la identidad docente presentes en los discursos y lineamientos acerca de la implementación del 3º ciclo de la EGB en dicha provincia; b) los significados y representaciones identitarias que se van constituyendo en las interacciones cotidianas en las escuelas; c) las maneras en que son recibidas y procesadas estas interpelaciones y representaciones por los docentes del 3º ciclo, en un trabajo interpretativo que supone también resistencias y reformulaciones. Este planteo supone un contrapunto entre lo macro -abordado a través del análisis de contenido de ciertos discursos públicos- y lo micro -examinado a través de un estudio de casos múltiples en diversas escuelas bonaerenses-.; Within Argentine educational reform, the 3rd stage of General Basic Education (EGB) is a central aspect, since it involves important differences with regard to the former educative system structure. This stage is composed by the former primary school 7th grade and secondary school 1st and 2nd year. Therefore, it involves the daily interaction of two distinct professional cultures: that of primary and secondary school teachers. In addition, the reform policy promotes a redefinition of teachers’ roles. The paper analyses the impact of this process on the construction of 3rd stage teachers’ professional identity in the Argentine Buenos Aires province. It encompasses different levels of research: a) the interpellations about teaches’ identity found in discourses and political measures regarding the 3rd stage implementation; b) the meanings and representations as to identity constructed during daily interactions in schools; c) the diverse ways these interpellations and representations are received, interpreted and processed by 3rd stage teachers. This approach attempts to explore the macro level through content analysis of public discourses and the micro level through a multiple case study in schools. It also attempts to relate both levels.

Androgen receptors in human melanoma cell lines IIB-MEL-LES and IIB-MEL-IAN and in human melanoma metastases Morvillo, V.; Luthy, Isabel Alicia; Bravo, A. I.; Capurro, M. I.; Portela, P.; Calandra, Ricardo Saul; Mordoh, Jose The presence and characteristics of androgen receptors (AR) have been des­cribed by our group in one human melanoma cell line. We now investigated their presence in two other human melanoma cell lines, IIB-MEL-LES and IIB-MEL-IAN, as well as in biopsies of human metastatic melanoma. Scatchard analysis revealed a single binding component for both cell lines, the apparent dissociation constant obtained being 15 nM, with a binding capacity of 280 fmol/mg total cell protein for IIB-MEL-LES cells and of 14 nM with a binding capacity of 206 fmol/mg total cell protein for IIB-MEL-IAN. When specifi­ci­ty was assessed, as seen before, not only androgen and anti­an­dro­gen, but also non-andro­ge­nic com­pounds were able to compete for [3H]-R1881 binding. When immu­nocyto­che­mis­try of IIB-MEL-LES and IIB-MEL-IAN cells was performed for AR, both cell lines were deeply stained in the nu­cleus whe­reas no staining was found for oestrogen and pro­ges­te­rone receptors. Every specimen of mela­no­ma metas­ta­ses tested for the presence of AR was deeply stained, and the intensity of the stai­ning was high in the majority. Several hormones and antihormones were tested for their ability to affect cell proli­fe­ration. On both cell lines, Testosterone, Dihydrotesterone, Oestradiol and Pro­ges­terone significantly stimulated cell proliferation, with reversion by Hydroxy-Flutamide, Casodex or Tamo­xi­fen.

Carboxylate-Bridged Copper(II)-Lanthanide(III) Complexes [{Cu3Ln2(oda)6(H2O)6}.12H2O]n (Ln = Dy, Ho, Er, Y; oda = oxydiacetate Rizzi, Alberto Claudio; Calvo, Rafael; Baggio, Ricardo Fortunato; Garland, María Teresa; Peña, Octavio; Perec, Mireille The hydrothermal reaction of Ln2O3 (Ln = Dy and Ho), Cu(OAc)2·2H2O, and oxydiacetic acid in the approximate mole ratio of 1:3:8 resulted in the formation of two new members of the isostructural series of polymers formulated as [{Cu3Ln2(oda)6(H2O)6}·12H2O]n, crystallizing in the hexagonal crystal system, space group P6/mcc (No. 192). Temperature-dependent magnetic susceptibilities and EPR spectra are reported for the heterometallic compounds Cu−Dy 1, Cu−Ho 2, Cu−Er 3, and Cu−Y 4. The results are discussed in terms of the structure of the compounds, the electronic properties of the lanthanide ions, and the exchange interactions between the magnetic ions.

A nonlinear panel method in the time domain for seakeeping flow problems D'elia, Jorge; Storti, Mario Alberto; Oñate, Eugenio; Idelsohn, Sergio Rodolfo A Lagrangian-type panel method, in the time domain, is  proposed for potential flows with a moving free surface. After a spatial semi-discretization, with a low-order scheme, the instantaneous velocity-potential and normal displacement on the moving free surface, are obtained by means of a time-marching scheme. The kinematic and dynamic boundary conditions, at the free surface, are non-lineal restrictions over the related Ordinary Differential Equation system and, for handle them, an alternative Steklov-Poincare operator  technique is proposed. The method is applied to sloshing like flow problems.

Optimal Design of Cams Cardona, Alberto; Lens, Elisabeth; Nigro, Norberto Marcelo We present a methodology to design cams for motor engine valve trains using a constrained optimization algorithm. The imposed constraints are the maximum valve lift and timings while the objective function is to maximize the time integral of the valve area opened to gas flow. A piecewise analytically defined acceleration is imposed, so that the time instants controlling the profile of accelerations are used as variables for optimization. The strategy takes into account some geometrical constraints, e.g. to avoid interference between intake and exhaust valves, and between valves and piston. Also, minimum and maximum levels of acceleration are limited to avoid excessive forces in the mechanisms chain, and to prevent the possibility of separation between cam and follower. Once an optimal lift profile is determined, the cam shape is computed using an inverse kinematics analysis that takes into account all the geometric nonlinearities introduced by the kinematical chain. Finally, the whole mechanism is verified in a dynamics analysis to check satisfaction of the criteria for design. Comparisons with standard profiles of motion were made. Also, the profile was evaluated in an experimental device, where the actual valve displacement was measured.

All-hexahedral element meshing: Automatic elimination of self-intersecting dual lines Calvo, Nestor Alberto; Idelsohn, Sergio Rodolfo There has been some degree of success in all-hexahedral meshing. Standard methods start with the object geometry defined by means of an all-quadrilateral mesh, followed by the use of the combinatorial dual to the mesh in order to define the internal connectivities among elements. For all of the known methods using the dual concept, it is necessary to first prevent or eliminate self-intersecting (SI) dual lines of the given quadrilateral mesh. The relevant features of SI lines are studied, giving a method to remove them, which avoids deforming the original geometry. Some examples of resulting meshes are shown where the current meshing method has been successfully applied.

Energy of interaction in colloids and its implications in rheological modeling Quemada, Daniel; Berli, Claudio Luis Alberto This work deals with the problem of deriving theoretical connections between rheology and interparticle forces in colloidal suspensions. The nature of interparticle forces determines the colloidal structure (crystalline order due to long range repulsive forces, flocculation due to attractive forces, etc.) and hence, the flow behavior of suspensions. The aim of this article is to discuss how these interactions enter the modeling of rheometric functions, in particular, the shear viscosity. In this sense, the main interactions commonly appearing in colloids are reviewed, as well as the role they play in phase transition behavior. Then, a series of approaches relating the interaction potential to viscosity is examined. The results of applying these models to experimental data are also discussed. Finally, examples of viscosity modeling for different interaction potentials are given, by using the structural model proposed previously by the authors. The possibility of relating the flow behavior of colloidal suspensions to the interaction between particles offers new perspectives for the study and technical applications of these systems.

Lista de los escorpiones bolivianos (Chelicerata: Scorpiones), con notas sobre su distribución; Checklist of the Bolivian scorpions (Chelicerata: Scorpiones), with notes on their distribution Acosta, Luis Eduardo; Ochoa, José A. Se presenta una lista actualizada de los escorpiones de Bolivia. Se mencionan 24 especies (tres de elias con dudas) y una subespecie, pertenecientes a las familias Bothriuridae, Buthidae e luridae. Para cadaespecie se proporciona una referencia bibliografica abreviada, así como la nómina completa de las localidades para las que ha sido citada. Brachistosternus ferrugineus (Thorell) y el genero andino Orobothriurus Maury (Bothriuridae) se citan por prirnera vez para Bolivia. Se discuten los motivos para excluir de la escorpiofauna boliviana a siete especies nominales citadas por autores previos. Se adjunta una lista de las localidades bolivianas, con sus coordenadas, donde se han recolectado escorpiones.; An updated checklist of the scorpions of BoIivia is presented. Twenty four species (three of them, with doubts) and one subspecies, belonging to the families Bothriuridae, Buthidae and luridae are listed. For each species, an abbreviated bibliographic reference and the complete list of known localities are given. Brachistosternus ferrugineus (Thorell) and the Andean genus Orobothriurus Maury (Bothriuridae) are mentioned for the first time from Bolivia. Seven nominal species cited by previous authors are excluded from the Bolivian scorpiofauna, and the reasons for these exclusions are discussed. All Bolivian localities where scorpions have been collected are listed in a gazetteer.

The arginine deiminase pathway in the wine lactic acid bacterium Lactobacillus hilgardii X1B: Structural and functional study of the arcABC genes Arena, Mario Eduardo; Manca, Maria Cristina; Muñoz, Rosario The genes implicated in the catabolism of the amino acid arginine by Lactobacillus hilgardii X1B were investigated to assess the potential for formation of ethyl carbamate precursors in wine. L. hilgardii X1B can use arginine via the arginine deiminase pathway. The complete nucleotide sequence of the arc genes involved in this pathway has been determined. They are clustered in an operon-like structure in the order arcABC. No evidence was found for the presence of a homologue of the arcD gene, coding for the arginine/ornithine antiporter. The arc genes have been expressed in Escherichia coli resulting in arginine deiminase (ArcA), ornithine carbamoyltransfera (ArcB) and carbamate kinase (ArcC) activities. The results indicate the need for caution in the selection of lactic acid bacteria for conducting malolactic fermentation in wine since arginine degradation could result in high amounts of ethyl carbamate.