Heavy-ion induced two-neutron transfer reactions and the role of pairing / Reacciones de transferencia de dos neutrones inducidas por iones pesados y el papel del apareamiento

Abstract Heavy-ion induced two-neutron transfer reactions (18O,16O) at 84 MeV were studied on several targets up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX magnetic spectrometer to detect the ejectiles. The obtained results indicate of the important role played by the nuclear paring.

Resumen Se estudiaron reacciones de transferencia de dos neutrones inducidas por iones pesados (18O, 16O) a 84 MeV en varios blancos hasta una alta energía de excitación del núcleo residual gracias al uso del espectrómetro magnético MAGNEX para detectar los residuos eyectados. Los resultados obtenidos indican el importante papel desempeñado por el apareamiento nuclear.

The NUMEN project: Heavy-Ion Double Charge Exchange reactions towards 0νββ NME determination / El proyecto NUMEN: reacciones de intercambio de cargas dobles de iones pesados hacia la determinación de 0νββ NME

Abstract NUMEN proposes cross sections measurements of Heavy-Ion double charge exchange reactions as an innovative tool to access the nuclear matrix elements, entering the expression of the life time of Neutrinoless double beta decay (0νββ). A key aspect of the projectis the use at INFN-Laboratori Nazionali del Sud (LNS) of the Superconducting Cyclotron (CS) for the acceleration of the required high resolution and low emittance heavy-ion beams and of MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles. The experimental measurements of double charge exchange reactions induced by heavy ions present a number of challenging aspects, since such reactions are characterized by very low cross sections. First experimental results give encouraging indication on the capability to access quantitative information towards the determination of the Nuclear Matrix Elements for 0νββ decay.

Resumen NUMEN propone mediciones de secciones eficaces de reacciones de intercambio de carga doble de iones pesados como una herramienta innovadora para acceder a los elementos de la matriz nuclear, entrando en la expresión del tiempo de vida de la desintegración beta doble sin neutrino (0νββ). Un aspecto clave del proyecto es el uso en INFN-Laboratori Nazionali del Sud (LNS) del ciclotrón superconductor (CS) para la aceleración de los haces de iones pesados de alta resolución y baja emitancia requeridos y del espectrómetro magnético de gran aceptación MAGNEX para la detección de los residuos eyectados. Las mediciones experimentales de reacciones de intercambio de carga doble inducidas por iones pesados presentan una serie de aspectos desafiantes, ya que tales reacciones se caracterizan por secciones eficaces muy bajas. Los primeros resultados experimentales dan una indicación alentadora sobre la capacidad de acceder a información cuantitativa para la determinación de los Elementos de la Matriz Nuclear para la descomposición de 0νββ.

Erratum: Raman spectral post-processing for oral tissue discrimination - a step for an automatized diagnostic system: erratum.

[This corrects the article on p. 5218 in vol. 8, PMID: 29188115.].

Raman spectral post-processing for oral tissue discrimination - a step for an automatized diagnostic system.

Most oral injuries are diagnosed by histopathological analysis of a biopsy, which is an invasive procedure and does not give immediate results. On the other hand, Raman spectroscopy is a real time and minimally invasive analytical tool with potential for the diagnosis of diseases. The potential for diagnostics can be improved by data post-processing. Hence, this study aims to evaluate the performance of preprocessing steps and multivariate analysis methods for the classification of normal tissues and pathological oral lesion spectra. A total of 80 spectra acquired from normal and abnormal tissues using optical fiber Raman-based spectroscopy (OFRS) were subjected to PCA preprocessing in the z-scored data set, and the KNN (K-nearest neighbors), J48 (unpruned C4.5 decision tree), RBF (radial basis function), RF (random forest), and MLP (multilayer perceptron) classifiers at WEKA software (Waikato environment for knowledge analysis), after area normalization or maximum intensity normalization. Our results suggest the best classification was achieved by using maximum intensity normalization followed by MLP. Based on these results, software for automated analysis can be generated and validated using larger data sets. This would aid quick comprehension of spectroscopic data and easy diagnosis by medical practitioners in clinical settings.

Determinación de la eficiencia de detección de Descripción: Descripción: D:/Scielo/Nucleus html/n 59/img/e01085916.jpgen tiroides utilizando el método Monte Carlo / Determination of the detection efficiency of Descripción: Descripción: D:/Scielo/Nucleus html/n 59/img/e01085916.jpgin thiroid using Monte Carlo method

El Método Monte Carlo fue la base para la estimación de la eficiencia de detección de , utilizando el detector identiFINDER ultra en geometría “tiroides”. Se discute la idoneidad de la metodología de calibración al comparar los resultados del Método Monte Carlo Directo y Corregido, con los valores de eficiencia calculados experimentalmente. El Método Monte Carlo Corregido fue la metodología adoptada debido a que el porcentaje de error estimado, respecto a los resultados experimentales, fue menor que el 10 %. Para las simulaciones, los parámetros geométricos del detector fueron optimizados, utilizando un estudio de tomografía computarizada. El arreglo detector – fuente puntual- fue simulado para obtener los factores de corrección a las distancias prefijadas, y el arreglo detector – maniquí simulador de tiroides- fue simulado para la obtención de la curva de eficiencia de detección, en función de la distancia de medición. Para validar la metodología propuesta, el Laboratorio de Dosimetría Interna del Centro de Protección e Higiene de las Radiaciones participó en un ejercicio de intercomparación regional de estimación, de actividad medida en tiroides, se utilizó para el cálculo de la misma, tanto la metodología tradicional de cálculo de eficiencia como la metodología basada en la utilización del Método Monte Carlo, y se alcanzaron resultados satisfactorios, en todos los casos. Como resultado final de este trabajo, fue obtenida la curva de eficiencia de detección en función de la distancia de , sin necesidad de utilizar simuladores físicos, supliendo, así, la carencia actual de los mismos.

Monte Carlo Method was the base to estimate the detection efficiency of of the identiFINDER ultra detector in “thyroid” geometry. The suitability of the calibration methodology is discussed using a comparison of the results of the Direct Monte Carlo Method and the Transfer Monte Carlo Method calculations with the values of experimentally calculated efficiency. Transfer Monte Carlo Method was the elected methodology because of the differences with the real detection efficiency stay below 10 %. In the simulations, the geometric parameters of the detector were found using a tomography study. The arrangement detector – point source was simulated to obtain the correction factors for preset distances, and the arrangement detector – thyroid phantom was simulated to obtain the detection efficiency curve in function of the distance for . In order to validate the proposed methodology the Internal Dosimetry Laboratory of the Centre for Radiation Protection and Hygiene participated in a regional intercomparison exercise of measured activity estimation in thyroid, for the estimation were used the traditional calculation methodology as well as the methodology base on Monte Carlo Method, the results were satisfactory in both cases. As a final result, the curves of detection efficiency for the measurement of in the thyroid gland was obtained without using physical phantoms, replacing the current lack of it.

SU-E-I-66: Is T2 Individual Correction in MRS for Fat Quantification Tool Necessary?

PURPOSE: In nonalcoholic steatohepatitis (NASH) the fat quantification is necessary. One of the most used in vivo quantification method is the magnetic resonance spectroscopy (MRS). It is well known the importance of T2 correction to improve the accuracy and precision of this method; however the T2 measurements require time consumption. In this work we estimated the T2 values for water and fat in NASH patient with different fat contents in order to verify if a generic T2 correction is adequate for fat quantification in the clinical routine. METHODS: 19 NASH patients (48±10 years, 9 female) underwent MR procedure several times. Imaging was performed on a 3.0T clinical MRI scanner using a 3P-Dixon method. MRS data was acquired using single voxel (3×3×3 cm) PRESS acquisition (TR=1500ms, 1024points, 2 KHz bandwidth). The PRESS acquisition was performed in a single TE (60 ms, 32 averages) and multiple TE (32,45,80 and 135 ms; 16 averages). The software jMRUI was used for peak quantification. The MRS results were T2 corrected using generic values (T2fat=55ms and T2water=25 ms) for single TE data and individual values estimated from multi-TE data before fat fraction calculation. A linear correlation was estimated between the fat fraction obtained using 3P-Dixon and the spectroscopy methods. RESULTS: The T2 values estimated were 69±14 and 27±3 ms for fat and water, respectively. The correlation coefficients between 3P-Dixon and the spectroscopy methods were: 0.75 for MRS-individual and 0.82 for MRS-general. CONCLUSIONS: The procedure using a generic T2 value was more correlated to Dixon than one using individual values, suggesting that is more important a good signal-to-noise ratio than a very precise T2 value for correction. The reduced range of T2water values doesn't reflect any considerable iron deposition in NASH patients. In diseases with low iron deposition it's not necessary the individual T2 correction for fat quantification from MRS data.

Characterization of the InSTEC’s low-background gamma spectrometer for environmental radioactivity studies / Caracterización del espectrómetro gamma de bajo fondo del INSTEC para estudios de radioactividad ambiental

ABSTRACT The capabilities of the LowBackground Gamma Spectrometer (LBGS) at InSTEC were studied for environmental purposes. Fifty three glines were identified in the LBGS background spectrum. The Minimum Detectable Activity for , , , , and were calculated using the detector’s volumetric efficiency simulated by Monte Carlo method. Validation was performed by absolute and relative analysis of radionuclide activities present in a marine sediment certified material.

RESUMEN Se determinan las potencialidades del Espectrómetro Gamma de Bajo Fondo del InSTEC con fines ambientales. Se identificaron 53 líneas gamma en el espectro de fondo natural del espectrómetro. Se calculan las actividades mínimas detectables para los radionucleidos , , , , and empleando la eficiencia volumétrica del detector simulada por Monte Carlo. Como validación se determinan, por vía absoluta y relativa, las actividades de los radionucleidos presentes en un estándar de sedimento marino.

Radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate) / Copolimerización por injerto radioinducido de acrilamida en el poli (3-hidroxibutirato)

The graft copolymer poly (3-hydroxybutyrate)-g- polyacrylamide[P (HB-g-AAm)] was synthesized by radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate). The study was conducted by the simultaneous irradiation method. The structure of [P (HB-g-AAm)] was identified by Fourier Transform Infrared (FTIR) spectroscopy. Thermal behavior of the graft copolymer was also studied by Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). According to the results, FTIR studies showed new signals (stretching-N-H) as an important evidence of grafting. The grafting degree, determined by ATG, was 10% and changes in thermodynamic parameter obtained from the DSC were detected. Such changes show a decrease in crystallinity and an increase in the glass transition temperature. These results demonstrate that the gamma radiation-induced graft copolymerization reaction of acrylamide onto PHB was successively achieved.

En el trabajo se realizó la síntesis del copolímero por injerto poli (3-hidroxibutirato)-g- poliacrilamida [P (HB-g-AAm)] por copolimerización de injerto radioinducido del monómero acrilamidaen el PHB. El estudio se llevó a cabo por el método de la irradiación simultánea. La estructura del copolímero se identificó por espectroscopía Infrarrojo por Transformada de Fourier (FTIR). Además, se realizó el estudio térmico del compuesto obtenido por análisis termogravimétrico (TGA) y calorimetría diferencial de barrido (DSC). De los resultados se encontraron señales (vibraciones de valencia -N-H) por FTIR que constituyen una importante evidencia de la reacción de injerto. El grado de injerto determinado por ATG fue de 10% y se detectaron cambios en los parámetros termodinámicos estudiados por DSC, que muestran una disminución de la cristalinidad y un aumento de la temperatura de transición vítrea. Los resultados demostraron la formación del copolímero por injerto inducido por radiaciones gamma.