Theory of Weak Hypernuclear Decay

The weak nonmesonic decay of Lambda-hypernuclei is studied in the context of a one-meson-exchange model. Predictions are made for the decay rate, p/n stimulation ratio and the asymmetry in polarized hypernuclear decay.Comment: Standard 41 page Latex fil

Intrinsic switching field distribution of arrays of Ni80Fe20 nanowires probed by in situ\mathit{in\, situ} magnetic force microscopy

The progress of magnetization reversal of weakly packed ferromagnetic Ni80Fe20 nanowire arrays of different diameters (40, 50, 70 and 100 nm) electrodeposited in polycarbonate membranes was studied by magnetic force microscopy (MFM). For such a low packing density of nanomagnets, the dipolar interactions between neighbouring wires can be neglected. The intrinsic switching field distribution has been extracted from in situ MFM images and its width was found to be considerably smaller than for densely packed nanowire arrays.Comment: 4 pages, 5 figures. To appear in Journal of Superconductivity and Novel Magnetis

Magnetic force microscopy investigation of arrays of nickel nanowires and nanotubes

The magnetic properties of arrays of nanowires (NWs) and nanotubes (NTs), 150 nm in diameter, electrodeposited inside nanoporous polycarbonate membranes are investigated. The comparison of the nanoscopic magnetic force microscopy (MFM) imaging and the macroscopic behavior as measured by alternating gradient force magnetometry (AGFM) is made. It is shown that MFM is a complementary technique that provides an understanding of the magnetization reversal characteristics at the microscopic scale of individual nanostructures. The local hysteresis loops have been extracted by MFM measurements. The influence of the shape of such elongated nanostructures on the dipolar coupling and consequently on the squareness of the hysteresis curves is demonstrated. It is shown that the nanowires exhibit stronger magnetic interactions than nanotubes. The non-uniformity of the magnetization states is also revealed by combining the MFM and AGFM measurements.Comment: 7 pages, 5 figure

Toxic effect of antibiotics in grapevine (Vitis vinifera 'Albariño') for embryo emergence and transgenic plant regeneration from embryogenic cell suspension

Regeneration of grapevine (Vitis vinifera L.) from embryogenic cultures after gene transfer is traditionally linked to a selection procedure using antibiotic containing media. The neomycin phosphotransferase II (npt-II) and hygromycin phosphotransferase (hpt) genes that confer resistance to the antibiotics kanamycin and hygromycin, respectively, have been the selectable marker genes most frequently used for selection of transgenic grapevines. In this work, the phytotoxic effects on embryo development and plant growth of these two antibiotics were examined in 'Albariño'. Embryogenic cell suspensions were evaluated based on a twostep strategy using untransformed and transformed tissues. The phytotoxic effect was significantly different at 20 mg∙L-1 (and higher) for kanamycin and at 5 mg∙L-1 (and higher) for hygromycin. Minimal killing concentrations of kanamycin and hygromycin for 'Albariño' cell suspensions were 50 and 12.5 mg∙L-1, respectively. Embryogenic cell suspensions were bombarded using the biolistic system with the construct pBI426, harboring the selectable npt-II gene, and incubated on kanamycin containing media to determine the best inhibitory concentration allowing embryo and shoot development of only transgenic events. Only 20 % of PCR-positive transgenic embryos and 20 % of plant regeneration resulted from embryos emerged on 30 mg∙L-1. However, 80 % of PCR-positive transgenic embryos but only 10 % of plant regeneration were obtained from embryos emerged on 40 mg∙L-1. The method described, based in untransformed and transformed plant material, could be used to determine the optimal antibiotic concentration for other V. vinifera cultivars for efficient selection and regeneration of transgenic events.

Adapting cognitive diagnosis computerized adaptive testing item selection rules to traditional item response theory

Currently, there are two predominant approaches in adaptive testing. One, referred to as cognitive diagnosis computerized adaptive testing (CD-CAT), is based on cognitive diagnosis models, and the other, the traditional CAT, is based on item response theory. The present study evaluates the performance of two item selection rules (ISRs) originally developed in the CD-CAT framework, the double Kullback-Leibler information (DKL) and the generalized deterministic inputs, noisy and gate model discrimination index (GDI), in the context of traditional CAT. The accuracy and test security associated with these two ISRs are compared to those of the point Fisher information and weighted KL using a simulation study. The impact of the trait level estimation method is also investigated. The results show that the new ISRs, particularly DKL, could be used to improve the accuracy of CAT. Better accuracy for DKL is achieved at the expense of higher item overlap rate. Differences among the item selection rules become smaller as the test gets longer. The two CD-CAT ISRs select different types of items: items with the highest possible a parameter with DKL, and items with the lowest possible c parameter with GDI. Regarding the trait level estimator, expected a posteriori method is generally better in the first stages of the CAT, and converges with the maximum likelihood method when a medium to large number of items are involved. The use of DKL can be recommended in low-stakes settings where test security is less of a concern

Efectos de un hidrocarburo aromático policíclico (ß naftoflavona) sobre biomarcadores de efecto en Corydoras paleatus en condiciones de campo y laboratorio

Polycyclic aromatic hydrocarbons (PAHs) are important anthropogenic sources of aquatic contamination. In this study, hepatic biomarker responses of Corydoras paleatus injected with one sublethal dose of a PAH (ß-naftoflavona, BNF) were assessed under laboratory and field conditions. Glutathion-S-transferase (GST) and catalase (CAT) hepatic activities, liver protein content (PC), condition factor (CF) and liver somatic index (LSI) were determined. Two bioassays were performed during winter time: laboratory (la) and field (ca). Fish were injected with 50 mg BNF/kg body weight dissolved in corn oil (ß-la y ßca); control fish received corn oil (C-la y C-ca). There were no differences between controls or in BNF injected fish in the assessed parameters. BNF provoked a tendency of increase in CAT and GST activities and lower values of CP; on the other hand, no differences were observed in the FC and IHS. In BNF field exposed fish (ß-ca) CAT activity was significantly stimulated vs. both field and laboratory controls; GST differences were detected both between ß-ca and ß-la and their respective controls. BNF exposure induced adverse effects principally in the enzymatic biomarkers of C. paleatus and those effects were modulated by the environmental conditions.Facultad de Ciencias Naturales y Muse

Efectos de un hidrocarburo aromático policíclico (ß naftoflavona) sobre biomarcadores de efecto en Corydoras paleatus en condiciones de campo y laboratorio

Polycyclic aromatic hydrocarbons (PAHs) are important anthropogenic sources of aquatic contamination. In this study, hepatic biomarker responses of Corydoras paleatus injected with one sublethal dose of a PAH (ß-naftoflavona, BNF) were assessed under laboratory and field conditions. Glutathion-S-transferase (GST) and catalase (CAT) hepatic activities, liver protein content (PC), condition factor (CF) and liver somatic index (LSI) were determined. Two bioassays were performed during winter time: laboratory (la) and field (ca). Fish were injected with 50 mg BNF/kg body weight dissolved in corn oil (ß-la y ßca); control fish received corn oil (C-la y C-ca). There were no differences between controls or in BNF injected fish in the assessed parameters. BNF provoked a tendency of increase in CAT and GST activities and lower values of CP; on the other hand, no differences were observed in the FC and IHS. In BNF field exposed fish (ß-ca) CAT activity was significantly stimulated vs. both field and laboratory controls; GST differences were detected both between ß-ca and ß-la and their respective controls. BNF exposure induced adverse effects principally in the enzymatic biomarkers of C. paleatus and those effects were modulated by the environmental conditions.Facultad de Ciencias Naturales y Muse

Efectos de un hidrocarburo aromático policíclico (ß naftoflavona) sobre biomarcadores de efecto en Corydoras paleatus en condiciones de campo y laboratorio

Polycyclic aromatic hydrocarbons (PAHs) are important anthropogenic sources of aquatic contamination. In this study, hepatic biomarker responses of Corydoras paleatus injected with one sublethal dose of a PAH (ß-naftoflavona, BNF) were assessed under laboratory and field conditions. Glutathion-S-transferase (GST) and catalase (CAT) hepatic activities, liver protein content (PC), condition factor (CF) and liver somatic index (LSI) were determined. Two bioassays were performed during winter time: laboratory (la) and field (ca). Fish were injected with 50 mg BNF/kg body weight dissolved in corn oil (ß-la y ßca); control fish received corn oil (C-la y C-ca). There were no differences between controls or in BNF injected fish in the assessed parameters. BNF provoked a tendency of increase in CAT and GST activities and lower values of CP; on the other hand, no differences were observed in the FC and IHS. In BNF field exposed fish (ß-ca) CAT activity was significantly stimulated vs. both field and laboratory controls; GST differences were detected both between ß-ca and ß-la and their respective controls. BNF exposure induced adverse effects principally in the enzymatic biomarkers of C. paleatus and those effects were modulated by the environmental conditions.Facultad de Ciencias Naturales y Muse

Biomarcadores hepáticos de la carpa (<i>Cyprinus carpio</i> L.): respuestas antioxidantes inducidas por la β-naftoflavona, un hidrocarburo aromático policíclico

Polycyclic aromatic hydrocarbons (PAHs) exert adverse effects in many aquatic organisms and fish among them. β-naphtoflavone (BNF) is a PAH inductor of biotransformation processes that potentially could enhance the production of reactive oxygen species promoting the responses of the cellular antioxidant defences. Hepatic biomarker responses were assessed in juvenile Cyprinus carpio injected with a sublethal dose of BNF; catalase (CAT), Superoxid dismutase (SOD),Glutathion S-transferase (GST) activities, the condition factor (FC) and the liver somatic index (IHS) were evaluated. Fish were acclimated to experimental conditions for 1 week (continuous flow potable water: 50 ml/ min; 2,5 g fish/L; photoperiod: 12 h L/D; temperature: 22 ºC; daily feeding ad libitum). At the beginning of the assays experimental fish (BNF) (n=10) were intraperitoneally injected with 50 mg BNF/kg. b. w. dissolved in corn oil; controls (C) (n=10) received corn oil. No fish mortality was observed along the assay. After 48 h, fish were killed, livers excised and FC and IHS index were determined. Then, tissues were homogenized and postmitoncondrial fractions were obtained; total protein content, and specific activities of CAT, SOD and GST were determined in this fraction. Statistical differences between groups C and BNF were performed by Student´s t test (p<0.05). A significant increase of GST (22.8%) and SOD (27.3%) activities were observed in BNF fish, but no differences were detected in CAT suggesting there is an effective capacity of SOD in removing the (O2 -) of the cellular media; the absence of differences in CAT would indicate that the formed H2O2 was only partially catalyzed. No statistical differences were observed in the IHS and FC indexes. These results will also allow considering the use of these valuable environmental bioindicators of this test species in the assessment of the quality of water bodies of the Buenos Aires Province.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Automated Analysis of MUTEX Algorithms with FASE

In this paper we study the liveness of several MUTEX solutions by representing them as processes in PAFAS s, a CCS-like process algebra with a specific operator for modelling non-blocking reading behaviours. Verification is carried out using the tool FASE, exploiting a correspondence between violations of the liveness property and a special kind of cycles (called catastrophic cycles) in some transition system. We also compare our approach with others in the literature. The aim of this paper is twofold: on the one hand, we want to demonstrate the applicability of FASE to some concrete, meaningful examples; on the other hand, we want to study the impact of introducing non-blocking behaviours in modelling concurrent systems.Comment: In Proceedings GandALF 2011, arXiv:1106.081