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2010-01-01
Resumen en español El objetivo de este trabajo es medir la radiactividad natural en pizarras utilizadas como material de construcción. Se analizaron pizarras fabricadas en la región de Extremadura-España como caso de estudio. Las concentraciones se determinaron por espectrometría gamma utilizando detectores coaxiales de HPGe. Se determinaron las actividades equivalente de radio y varios índices de riesgo. Así mismo se compararon los resultados con los obtenidos en la bibliografía en (mas) otros países del mundo. Los resultados muestran que los valores medios de concentración debido al 40K, 226Ra y 232Th fueron 840, 29 y 75 Bq/kg, respectivamente. La actividad equivalente de radio fue inferior al valor de 370 Bq/kg establecido como norma, y los otros índices de riesgo también fueron inferiores a sus límites Resumen en inglés The aim of this work is to measure the natural radioactivity in slates used as building material. Slates manufactured in the region of Extremadura-Spain were used as a study case. The concentrations were determined by gamma spectrometry using an HPGe coaxial detector. Radium equivalent activities (Ra eq) and various hazard indices were also calculated. Results were also compared with the data available in the literature for other countries of the world. The results show t (mas) hat the average values of the concentrations due to 40K, 226Ra and 232Th were found 840, 29 and 75 Bq/kg, respectively. The radium equivalent activity was less than the accepted standard criterion value of 370 Bq/kg and the values of other hazard indices were also below their limit values
2005-12-01
Resumen en español La hipótesis etiológica de la leucemia infantil, que adjudica a los campos electromagnéticos de baja frecuencia la inducción de esta enfermedad, continúa sin confirmación. Para esclarecer la posible influencia del componente magnético del campo electromagnético de baja frecuencia (ELF) en la vivienda, teniendo en cuenta el influjo de la radiactividad natural, se desarrolló un estudio de caso control en Ciudad de La Habana en el período comprendido de 1996 al 200 (mas) 0, a partir de la incidencia de leucemia infantil. Niños sanos y enfermos, respectivamente, fueron pareados por edad, escuela y sexo, seleccionados en el Registro Nacional de Cáncer. La varianza combinada del campo ELF y del perfil gamma mostró estructuras contrastadas en las viviendas de sanos y de enfermos, y se halló que el riesgo se incrementa con la intensidad del campo magnético. En el lugar y período estudiados, el componente magnético del campo ELF explicaría alrededor del 16 % de la incidencia y la dosis gamma equivalente a cerca del 3,0 de la leucemia infantil. Resumen en inglés The etiological hypothesis of childhood leukemia that relates low frequency electromagnetic fields to the induction of this disease is still unconfirmed. In order to clarify the possible influence of the magnetic component of low frequency electromagnetic field (ELF) on the house, taking into account the natural radioactivity inflow, a case-control study was carried out in the City of Havana from 1996 to 2000, on the basis of childhood leukemia incidence. Healthy and sick (mas) children were respectively matched by age, school and sex, being all the cases selected from the National Registry of Cancer. The combined variance of ELF electromagnetic field and gamma profile showed contrasting structures in the houses of healthy and of sick children, and it was found that the risk increases with the electromagnetic field intensity. In the studied period and place, the magnetic component of the ELF electromagnetic field would account for approximately 16 % of leukemia incidence as well as the gamma dose equivalent to 3 % of childhood leukemia cases.
Two-proton emission in the decay of Ar-31
18 pages, 7 figures, 2 tables.-- PACS nrs.: 23.40.Hc; 27.30.+t. | Several beta-delayed two-proton branches were observed in the decay of Ar-31, the most intense ones proceeding through the isobaric analogue state (IAS) in Cl-31. The mechanism of the two-proton emission is studied via the energy and ...
The nuclear structure of Th-229
25 pages, 5 tables, 9 figures.-- PACS nrs.: 21.10.-k; 23.20.-g; 23.20.Lv; 23.20.Nx.-- Available online Dec 5, 2001. | The γ-rays following the β- decay of Ac-229 have been investigated by means of γ-ray singles and γγ-coincidence measurements using Ge detectors. Multipolarities of 40 transitions in ...
The nuclear structure of Fr-227
26 pages, 4 tables, 10 figures.-- PACS nrs.: 21.10.−k; 23.20.−g; 23.20.Lv; 23.20.Nx. | The γ-rays following the β- decay of Rn-227 have been investigated by means of γ-ray singles and γγ-coincidence measurements using an array of 12 Compton-suppressed Ge detectors. The fast-timing βγγ(t) method has ...
The doubly closed shell nucleus Sn-132(50)82
23 pages, 4 tables, 10 figures. | The structure of excited states in Sn-132, fed in the β-decay of In-132, has been investigated. Absolute intensities were deduced from γ-singles measurements. From multi-spectrum analysis of γ-lines the half-life of In-132 was determined to be 186 ± 22 ms. A level s...
The beta 2p decay mechanism of Ar-31 | The β2p decay mechanism of Ar-31
23 pages, 10 figures.-- PACS nrs.: 23.40.Hc; 27.30.+t.-- Printed version published on Sep 11, 2000. | We have measured the beta-decay of Ar-31 with a high granularity setup sensitive to multiparticle decay branches. Two-proton emission is observed from the isobaric analog state in Cl-31 to the four ...
Study of β-delayed 3-body and 5-body breakup channels observed in the decay of Li-11
12 pages, 5 figures, 3 tables.-- PACS nrs.: 23.40.Hc; 27.20.+n.-- Printed version published Sep 15, 2008.-- ArXiv pre-print available at: http://arxiv.org/abs/0806.3025 | The β-delayed charged particle emission from Li-11 has been studied with emphasis on the three-body nαHe-6 and five-body 2α3n cha...
Study of the giant Gamow-Teller resonance in nuclear β-decay: The case of Ar-32
19 pages, 9 figures, 3 tables. | Delayed proton and gamma emissions following the β-decay of Ar-32 have been studied. The half-life of Ar-32 is 98 ± 2 ms, and the T = 2 analogue state in Cl-32 lies at the excitation energy 5036 ± 12 keV. From the intensity of the feeding to this state the proton int...
Search for stable octupole deformation in Fr-225
52 pages, 11 figures, 10 tables.-- PACS nrs.: 23.20.−g; 23.20.Lv; 25.45.Hi; 25.55.−e; 27.90.+b. | Levels in Fr-225 have been studied by gamma-ray and conversion-electron spectroscopy following the beta-decay of Rn-225 and by the Ra-226(t,alpha)Fr-225 single-proton-pickup reaction. Multipolarities we...
Quenched E1 transition rates in Th-231
24 pages, 5 tables, 5 figures.-- PACS nrs.: 21.10.−k; 21.10.Tg; 21.10.Re; 23.20.−g; 23.20.Lv; 27.90.+b. | The fast timing βγγ(t) method has been used to measure lifetimes of the low-lying levels in Th-231 populated in the β- decay of Ac-231. The half-life of the K-π = 5/2(-) band-head at 185.7-keV w...
Quadrupole deformed and octupole collective bands in Ra-228
19 pages, 4 tables, 4 figures.-- PACS nrs.: 21.10.-k; 23.20.-g; 23.20.Lv; 23.20.Nx. | Spins and parities for collective states in Ra-228 have been determined from conversion electron measurements with a mini-orange β spectrometer. The fast-timing βγγ(t) method has been used to measure lifetimes of T...
Properties of the C-12 10 MeV state determined through β-decay
16 pages, 1 table, 10 figures.-- PACS nrs.: 23.40.-s; 26.20.+f; 27.20.+n.-- Printed version published Oct 3, 2005. | The β-delayed triple-α particle decay of B-12 has been measured with a setup that favours coincidence detection. A broad state in C-12, previously reported around 10 MeV, has been see...
Probing the Li-11 halo structure through β-decay into the Be-11(*) (18 MeV) state
10 pages, 1 table, 4 figures.-- PACS nrs.: 23.40.Hc; 27.20.+n. | An experimental study of β-delayed charged particles (H, He, Be) from Li-11 shows a β-feeding to an excited state at 18.15(15) MeV in Be-11 with a large Gamow-Teller strength, B-GT ≥ 1.6. Branching ratios and reduced widths of 2-, 3- a...
Persistence of octupole correlations in Ra-231
38 pages, 8 tables, 9 figures.-- PACS nrs.: 23.20.-g; 21.10.Tg; 21.10.Re; 27.90.+b.-- Printed version published Apr 9, 2001. | The structure of Ra-231, the heaviest odd Ra nucleus currently accessible for detailed spectroscopic investigation, has been studied in the beta (-) decay of Fr-231. The mai...
2003-12-01
Resumen en español Las diferencias regionales en la composición de las agregaciones de fitoplancton en varias lagunas costeras del Delta Exterior del Río Magdalena (costa caribeña colombiana) fueron determinadas utilizando el conteo microscópico y mediciones de pigmentos por HPLC. Los sitios de estudio pueden ser clasificados como 1) un grupo de lagunas límnicas con concentraciones de chl a relativamente bajas (5.5-19 µg/l) y una alta carga de materia inorgánica, 2) un grupo de lagun (mas) as salobres con una alta concentración de clorofila a (chl a) (62-90 µg/l) y una gran cantidad de seston orgánico, (dos lagunas en transición entre el grupo 1 y 2, y 3) una bahía completamente marina con una muy baja concentración de chl a (0.3 µg/l) y de seston. Las variaciones regionales en la salinidad de las lagunas se deben a la incursión de agua proveniente del Río Magdalena o a la entrada de agua de mar desde el Caribe. Todas las lagunas son de baja profundidad (menos de 2 m) con profundidades de disco Secchi pequeñas (20 a 30 cm). Con excepción de las lagunas salobres eutróficas, en donde ambos métodos mostraron a las cianobacterias como el grupo algal prevalente, se encontraron grandes discrepancias en la composición de las comunidades algales según el método aplicado.De acuerdo con el análisis microscópico, el fitoplancton de la bahía marina y el de las lagunas límnicas y transientes estuvo constituído principalmente (en varios casos exclusivamente) de diatomeas. Por otra parte, el análisis de pigmento indicó a las cianobacterias como el grupo algal dominante en todas las lagunas costeras, con un incremento porcentual desde las lagunas límnicas a través de las en transición hasta las lagunas salobres.La filtración fraccionada de fitoplancton marcado con 14C reveló que las algas con tamaño 20 µm jugaron un rol insignificante en la producción primaria. Solamente en la bahía del mar Caribe el 14% del 14CO2 fue asimilado por organismos >20 µm. Asumimos que los organismos pequeños están poco representados en las observaciones microscópicas debido a las grandes dificultades en su conteo e identificación de, debido al detritus y/o sedimento presente en las muestras. Por esto, creemos que estos pequeños organismos (probablemente cianobacterias picoplanctónicas) son representadas de una mejor manera a través del análisis de pigmentos. Resumen en inglés The regional differences in the composition of the phytoplankton assemblages in several coastal lagoons of the "Outer Delta of the Río Magdalena" (Caribbean coast of Colombia) were determined using microscopic counting and HPLC-pigment measurements. The study sites can be classified as 1) a group of limnic lagoons with relatively low (5.5-19 µg/l) chlorophyll a (chl a)concentrations and high inorganic suspension loading, 2) a group of brackish lagoons with high (62-90 � (mas) �g/l) chl a concentrations and high amounts of organic seston, (two further lagoons form a transition between group 1 and 2, and 3) a fully marine Caribbean bay with very low (0.3 µg/l) chl a and seston concentrations. The regional variations in salinity of the lagoons are due to inflow of water from the Río Magdalena or to inflow of Caribbean Sea water. All lagoons are very shallow (less than 2 m) with small Secchi depths (20 to 30 cm). With the exception of the eutrophic brackish lagoons, where both methods indicated cyanobacteria to be the prevalent algal group, great discrepancies were encountered in all other study sites between the compositions of the algal communities obtained with both approaches. According to the microscopic analysis the phytoplankton of the marine Caribbean bay and the limnic and transient coastal lagoons consisted mainly (in several cases exclusively) of diatoms. The pigment analysis, on the other hand, indicated that cyanobacteria were the dominant algal group in all coastal lagoons, their percentage increased from the limnic over the transient to the brackish lagoons. Fractionated filtration of 14C-labelled phytoplankton revealed that algae of 20µm size played only an insignificant role in primary production. Only in the Caribbean bay 14% of the 14CO2 was taken up by organisms >20µm. We assume that the small forms are greatly underrepresented in microscopic observations due to extreme difficulties in identification and counting caused by detritus and/or sediment loadings of the samples. We therefore believe that these small forms (probably mostly picoplanktonic cyanobacteria) are better represented by pigment analysis.
2008-04-01
Resumen en español El objetivo de este estudio fue demostrar la llegada al cerebro de la molécula de eritropoyetina recombinante humana, con bajo contenido en ácidos siálicos, administrada por vía nasal en el gerbo de Mongolia y el primate Macaca fascicularis, así como la seguridad de aplicación nasal en ambas especies. Se emplearon 18 gerbos de Mongolia a los cuales se les administró eritropoyetina marcada con I125. La radioactividad asociada al bulbo olfatorio y al cerebelo fue det (mas) erminada mediante un contador gamma. En un segundo experimento se administró eritropoyetina por vía nasal en 10 monos. El contenido de eritropoyetina en suero y líquido cefalorraquídeo obtenido por punción lumbar fue determinado por un ELISA que cuantifica la cantidad de molécula presente por mL. Se detectó un 0,8% de la radioactividad aplicada por la vía nasal, en el bulbo olfatorio, 5 min después de la aplicación en el gerbil de Mongolia. En el M. fascicularis se determinó un 0,15% de la dosis aplicada por vía nasal en el líquido cefalorraquídeo lumbar a los 15 min. No se observaron cambios en los parámetros sanguíneos en estas especies. Los resultados sugieren que la vía nasal constituye una alternativa de acceso no invasivo y seguro de la molécula de eritropoyetina humana recombinante al SNC, que puede tener uso como neuroprotector en accidentes cerebrovasculares, que constituyen en la actualidad un problema de salud humana. Resumen en inglés Our propose was to demonstrate the brain access of the recombinant human erythropoietin, with low sialic acid content, in the Mongolian gerbil and Macaca fascicularis, as well as the safety of nasal administration in both species. Eighteen Mongolian gerbils received intranasally I125 labelled erythropoietin. Olfactory bulb and cerebellum-associated radioactivity were measured by a gamma counter. In a second experiment, erythropoietin was intranasally administered to 10 mo (mas) nkeys. Erythropoietin content in serum and cerebrospinal fluid obtained by lumbar puncture was determined by an ELISA method. From the intranasal administered radioactivity, a 0,8% was detected in the olfactory bulb at 5 min. In M. fascicularis, a 0,15% of the dose was determined in the cerebrospinal fluid 15 min after the intranasal administration. Treatment related-changes in blood parameters in both species were not observed. Results suggest that nasal route may be an alternative, non invasive and sure mode of access to the brain for the erythropoietin, which can be used as neuroprotector in stroke, a current health problem nowadays.
24 pages, 9 figures.-- PACS nrs.: 23.40.Hc; 27.20.+n; 24.80.+y.-- Available online 17 August 2001. | In β-decay experiments on C-9 at CERN/ISOLDE the β-strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in B-9. A large β-strength...
Octupole correlations in Ra-229
36 pages, 5 tables, 9 figures.-- PACS nrs.: 23.20.−g; 21.10.Tg; 21.10.Re; 27.90.+b. | The structure of Ra-229 has been studied in the β- decay of Fr-229. Spins and parities have been determined from the conversion electron measurements, while half-lives for the 137.5, 142.7, 168.8, 213.0 and 479.0 k...
32 pages, 7 figures, 5 tables.-- PACS nrs.: 21.10.-k; 21.10.Tg; 21.10.Re; 23.20.-g; 23.20.Lv; 27.90.+b.-- Printed version published Oct 15, 2008.-- ArXiv pre-print available at: http://arxiv.org/abs/0808.0790 | The low-energy structure of Ac-231 has been investigated by means of γ ray spectroscopy f...
New information on β-delayed neutron emission from Be-12, Be-14
17 pages, 3 tables, 5 figures, 1 appendix.-- PACS nrs.: 23.40.Hc; 27.20.+n. | The β-delayed neutron branches from neutron-rich Be-isotopes have been measured with a setup sensitive down to thermal energies. For Be-14 a new value of P(n) = 101 ± 4% has been found for the total neutron-emission probab...
New information on the β-decay of Li-11 from Doppler broadened γ lines
16 pages, 2 tables, 4 figures.-- PACS nrs.: 23.40.-s; 23.20.-g; 27.20.+n.-- Printed version published May 17, 2004. | The γ-ray spectrum following β-decay of Li-11 has been remeasured at the ISOLDE facility at CERN. Two new transitions were observed through the use of large Ge-detectors. Most γ-deca...
MARIE CURIE, UNA GRAN CIENTIFICA, UNA GRAN MUJER
2006-01-01
Resumen en español Marie Curie y su esposo Pierre, fueron los descubridores de la radioactividad, junto a los elementos polonio y radio. Marie dedicó más de treinta y cinco años de su carrera científica al estudio de esta entidad. Con tenacidad y esfuerzo logró destacarse en una época donde el machismo y la xenofobia estaban presentes en todas partes. Por sus méritos, fue la primera persona en recibir dos premios Nobel: el de Física en 1903 y el de Química en 1911. Para los autores de esta publicación es un orgullo traer nuevamente a la luz la vida y obra de esta extraordinaria mujer Resumen en inglés Marie Curie and her husband Pierre, were the discoverers of radioactivity and also the polonium and radium elements. Marie dedicated thirthy five years of her scientific career to the study of this subject. With her tenacity and effort, she managed to stand out in a time where you could find sexism and xenophobia in every corner. Because of her merits she was the first person in receive two Nobel prizes: Physics in 1903 and Chemistry in 1911. For the authors of this publication it is an honor to bring this extraordinary women's life and work back to life
Low-lying resonance states in the Be-9 continuum
8 pages, 1 table, 4 figures.-- PACS nrs.: 23.40.Hc; 21.10.Hw; 27.20.+n.-- Printed version published Jul 7, 2005. | Excited states in Be-9 from 2 to 9 MeV are studied via beta delayed particle emission from Li-9. The broad overlapping particle unbound states are investigated using an extension of an ...
2000-10-01
Resumen en español Se realizó un estudio en una población de quebracho colorado chaqueño (Schinopsis balansae Engl.), principal especie forestal de valor económico del Parque Chaqueño Húmedo de Argentina, seleccionando ejemplares por su altura y diámetro altura de pecho (DAP). Se colocó una solución de KH2 32PO4 , a 0,10 m y 0,20 m de profundidad. Semanalmente durante 70 días, se determinó la concentración de radioactividad en hojas maduras y enteras de las ramas de un año. En (mas) ambas profundidades se detectó la presencia de raíces fisiológicamente activas, siendo mayor en la profundidad de 0,10 m, coincidiendo con la profundidad del horizonte A Resumen en inglés The study was conducted on a population of quebracho colorado chaqueño (Schinopsis balansae Engl.), the principal forest species of economic value in Argentina’s Chaqueño Húmedo Park. Individuals of this species were selected according to their height and trunk diameter (DAP). A solution of KH2 32PO4 was applied at two different depths 0.10 m and 0.20 m. For 70 days, the concentration of radioactivity in whole mature leaves in the one year old branches was determined (mas) weekly. The presence of physiologically active roots was detected at both depths, but the highest root activity was registered at 0.10 m coinciding with the A soil horizon
Beta-delayed triton emission in the decay of He-8
8 pages,1 table, 5 figures. | A β-delayed triton branch with an intensity of (0.9 ± 0.1)% has been observed in the decay of He-8. The triton energy spectrum was measured with a specially designed ΔE − E telescope. These data as well as an earlier measured β-delayed neutron spectrum cannot be explain...
22 pages, 6 figures.-- PACS nrs.: 23.40.−s; 27.30.+t; 29.30.Ep; 29.30.Kv; 21.60.Cs. | Erratum to this paper published on Oct 1998 in Nuclear Physics A 641(4): 529 (1998), available at: https://digital.csic.es/handle/10261/12171 | A complete study of Ar-31 beta decay has been made by high-resolution ...
2006-10-01
Resumen en español Presentamos el caso de una mujer de 66 años con diagnóstico de hiperparatiroidismo primario por adenoma paratiroideo ectópico mediastinal realizado por gammagrafía paratiroidea con 99mtc-metoxi-isobutil-isonitrito (Tc99-MIBI). Fue intervenida exitosamente mediante la técnica de videotoracoscopia. Durante el procedimiento se utilizó la medición de parathormona y a los 10 minutos de extirpado el adenoma se obtuvo un descenso mayor del 50% del basal. La sonda de detec (mas) ción gamma no fue efectiva in situ por la superposición del radioisótopo con el miocardio pero confirmó la radioactividad dentro del quirófano una vez extirpado el adenoma. La paciente normalizó los valores de calcemia y parathormona en el postoperatorio y permaneció normocalcémica luego de 9 meses de seguimiento. En nuestro caso, la localización prequirúrgica y el monitoreo de parathormona intraoperatoria fueron de gran utilidad para el éxito quirúrgico, la sonda detectora marcada con Tc99-MIBI no fue efectiva in situ pero confirmó la radioactividad una vez extirpado el adenoma. El tratamiento quirúrgico endoscópico por videotoracoscopia fue bien tolerado, menos doloroso que la toracotomía y acortó el tiempo de internación. Resumen en inglés We report a 66 years old woman with a diagnosis of primary hyperparathyroidism. Localization to mediastinum was obtained with parathyroid scintigraphy using 99mtc-methoxy-isobutyl-isonitrite (Tc99-MIBI). The patient was successfully operated upon by means of a videothora-coscopic approach. During the procedure serum parathormone was measured before and 10 minutes after adenomectomy, showing a more than 50% reduction from the basal level. An attempt to detect the precise s (mas) ite of the adenoma with a Tc99-MIBI probe was unsuccessful because of its proximity to the myocardium, but radioactivity was confirmed on the surgical specimen after resection. The patient's calcemia and parathormone levels became normal during the postoperative course and she remains normocalcemic 9 months after the procedure. In our case, preoperative localization and intraoperative parathormone measurements were both very useful for confirming surgical success; the intraoperative localization with a radioactive probe was not useful, but radioactivity was confirmed after resection on the surgical specimen. The endoscopic surgical procedure with videothoracoscopy was well tolerated, less painful than a thoracotomy, and it shortened the hospitalization period.
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