A MWPC with a cathode coupled delay line read-out as radioactivity detector for DNA repair studies

A non selective method for the isolation of DNA repair-deficient mutants in mammalian cells is discussed. The method requires radioactive labelling of the short DNA sequences synthesized during repair of damaged regions. Mutants should be recognized by the absence of radioactive incorporation into thier DNA. A multiwire proportional chamber (MWPC) is proposed as a suitable radioactivity detector. The performance of a MWPC prototype with a cathode coupled delay line read-out is described and is shown to be adequate for this application. The main avaantages of a MWPC are reviewed with respect to other methods used for β− radioactivity counting of biological samples, such as liquid scintillators or autoradiography: the proposed detection method is non destructive for the cells, which are being kept alive for further biological studies; furthermore many cell clones can be screened within a reasonable time

ELECTRONIC AUTORADIOGRAPHY OF LIVING HUMAN-CELLS WITH A MWPC

Abstract The use of multiwire proportional chamber (MWPC) for mapping the incorporation of a radioactive precursor of DNA biosynthesis by aggregates of cells is discussed. The resolving power, sensitivity and linearity of the developed system are shown, together with preliminary "electronic autoradiograms" of 14C-labelled cells

DNA-repair deficient cells identification with a multiwire proportional chamber

Abstract Tritium labelled mammalian cells with defective repair of UV-induced damage have been identified by using a MWPC as a position sensitive radioactivity detector. The resolving power (≅1.5mm FWHM), sensitivity (≅101Bq/cm2), efficiency (≅10%) and uniformity (≅4%) of the detection system are shown and "electronic autoradiograms" of normal and mutant cultures are presented; cells, rescued after the radioactivity measurement, retain their cloning ability

Relativistic description of 3He(e,e'p)2H

The Relativistic Distorted-Wave Impulse Approximation is used to describe the $^3$He($e,e^\prime p$)$^2$H process. We describe the $^3$He nucleus within the adiabatic hyperspherical expansion method with realistic nucleon-nucleon interactions. The overlap between the $^3$He and the deuteron wave functions can be accurately computed from a three-body calculation. The nucleons are described by solutions of the Dirac equation with scalar and vector (S-V) potentials. The wave function of the outgoing proton is obtained by solving the Dirac equation with a S-V optical potential fitted to elastic proton scattering data on the residual nucleus. Within this theoretical framework, we compute the cross section of the reaction and other observables like the transverse-longitudinal asymmetry, and compare them with the available experimental data measured at JLab.Comment: 4 pages, 3 figures. Proceedings of the 21st European Few Body Conference held in Salamanca (Spain) in August-September 201

Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids

We have carried out extensive equilibrium molecular dynamics (MD) simulations to investigate the Liquid-Vapor coexistence in partially miscible binary and ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the time evolution of the density profiles and the interfacial properties in a temperature region of the phase diagram where the condensed phase is demixed. The composition of the mixtures are fixed, 50% for the binary mixture and 33.33% for the ternary mixture. The results of the simulations clearly indicate that in the range of temperatures $78 < T < 102 ^{\rm o}$K, --in the scale of argon-- the system evolves towards a metastable alternated liquid-liquid lamellar state in coexistence with its vapor phase. These states can be achieved if the initial configuration is fully disordered, that is, when the particles of the fluids are randomly placed on the sites of an FCC crystal or the system is completely mixed. As temperature decreases these states become very well defined and more stables in time. We find that below $90 ^{\rm o}$K, the alternated liquid-liquid lamellar state remains alive for 80 ns, in the scale of argon, the longest simulation we have carried out. Nonetheless, we believe that in this temperature region these states will be alive for even much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures. Figures with better resolution available upon request. Accepted for publication in Phys. Rev. E Dec. 1st issu

CARBÓN DE LA PANOJA (Sporisorium reilianum f. sp. zeae) DEL MAÍZ (Zea mays L.)

El maíz (Zea mays L.) es un cultivo susceptible a diferentes patologías que pueden desarrollarse a lo largo de su ciclo de crecimiento. En el mismo pueden generarse dos enfermedades que son denominadas con el nombre de carbón: el carbón común del maíz, causado por Ustilago maydis (DC.) Corda y el carbón de la panoja del maíz, causado por Sporisorium reilianum f. sp. zeae (Kühn) Langdon &amp; Fullerton.En Argentina, el carbón común (U. maydis) es el de mayor distribución y el que normalmente se encuentra, campaña tras campaña, en todas las regiones productoras de maíz (Hirschhorn, 1941; Astiz Gassó &amp; Molina, 2010). En la actual campaña agrícola 2020/21, se ha detectado una reemergencia del carbón de la panoja en la zona sur de las provincias de Córdoba y Santa Fe. Atentos a esta situación, y para empezar a generar trabajos de identificación, cuantificación y prevención de esta problemática, es que se publica este informe técnico, donde han participado en conjunto la Universidad Católica de Córdoba, Universidad Nacional de La Plata, Oro Verde, INTA Pergamino, SENASA Córdoba y SENASA Central, desde la Dirección de Información Estratégica Fitosanitaria

Relativistic versus Nonrelativistic Optical Potentials in A(e,e'p)B Reactions

We investigate the role of relativistic and nonrelativistic optical potentials used in the analysis of ($e,e'p$) data. We find that the relativistic calculations produce smaller ($e,e'p$) cross sections even in the case in which both relativistic and nonrelativistic optical potentials fit equally well the elastic proton--nucleus scattering data. Compared to the nonrelativistic impulse approximation, this effect is due to a depletion in the nuclear interior of the relativistic nucleon current, which should be taken into account in the nonrelativistic treatment by a proper redefinition of the effective current operator.Comment: Added one new figure, the formalism section has been enlarged and the list of references updated. Added one appendix. This version will appear in Phys. Rev. C. Revtex 3.0, 6 figures (not included). Full postscript version of the file and figures available at http://www.nikhefk.nikhef.nl/projects/Theory/preprints

Características de la canal y de la carne en la raza caprina Bermeya. Comparación con el Ternasco de Aragón y lechales de la raza Murciano-Granadina

Se ha estudiado la calidad de la raza caprina Bermeya: lechales ligeros (BL) y cabritos pesados de explotación tradicional (BP), que se compararon con productos reconocidos (lechal de la raza Murciano-Granadina (MG) y corderos amparados bajo la IGP Ternasco de Aragón (TA). Los animales fueron criados y sacrificados en condiciones comerciales, y seleccionados por las respectivas Asociaciones de Productores y Consejo Regulador. Los porcentajes de hueso y músculo fueron mayores, y el de grasa inferior, en Bermeya (P < 0,001), encontrándose, igualmente, diferencias en la composición química de la carne. Los animales bermeyos presentaron valores de pH superiores (P < 0,001) a los de MG o TA. Los BP presentaron un índice de rojo y croma mayor respecto a BL. Tanto el tipo de animal como el tiempo de maduración afectaron significativamente a la textura. Así, MG mostró el mayor valor al 20% de compresión (C20) a 2 días de maduración (P < 0,001) y el TA los menores al 80% de compresión (C80) en todos los tiempos de maduración (P < 0,001). Se observaron diferencias significativas en casi todos los ácidos grasos analizados y en la intensidad de olor a especie (P < 0,05), terneza, jugosidad e intensidad de flavor a especie (P < 0,001), valoradas por un panel entrenado. En aceptabilidad global y de la terneza (consumidores), BL presentaron puntuaciones superiores (P < 0,001) a BP, aunque inferiores a las de los productos de referencia. Los resultados obtenidos sugieren, no obstante, una buena aceptación de los productos de la raza Bermeya y un cierto grado de diferenciación con los productos con los que han sido comparados Meat quality characteristics from Bermeya goat breed were studied. Light suckling kids (n = 12) and heavy kids from the traditional production system (n = 10) were compared with reference products from the Spanish market (suckling kids from Murciano-Granadina breed (MG); n = 12 and light lamb included in the Ternasco de Aragón Protected Geographic Indication (TA); n = 12). Animals were reared and slaughtered under commercial conditions, and selected from the respective Breeder Associations. Bermeya carcasses showed greater percentage of bone and muscle (P < 0.001), and lower percentage of fat in comparison with the other types, differing also in the chemical meat composition. pH values were higher in both Bermeya breed types than in MG and TA. Redness and Chroma increased with age in the Bermeya breed. Both type of animal and ageing affected textural variables. Murciano-Granadina meat showed the highest value of compression at 20% (C20) at 2 days of ageing (P < 0.001) and TA the smallest at 80% of compression rate (C80) at all the ageing times analyzed (P < 0.001). Differences between commercial types were observed both in most fatty acids and in the intensity of species odor (P < 0.05), tenderness, juiciness and specie flavour (P < 0.001) evaluated by trained panelists. A higher tenderness and overall acceptability scores were given by consumers to light Bermeya in comparison with heavy Bermeya kids (P < 0.001), and both were lower than those of the reference products. Results suggest a good acceptability and certain degree of differentiation from Bermeya breed products with respect to those compared with