No abstract

The use of activation analysis for the determination of microgram quantities of Mn and Zn in sea water was investigated.Total Mn and Zn were separated from the other elements of sea water by coprecipitation with iron as hydroxide, and divalcnt Mn and Zn were separated by extraction with diethyldithiocarbamate.Analyses were made from samples of water from different locations and depths of the North Pacific, Atlantic, and the Gulf of Mexico.Evidence indicates a substantial portion of Mn and Zn is held in sea water in a non-dialyzable and non-extractable form.INTRODUC '.lXON Increasing interest in trace elements in sea water makes it desirable to explore the application of sensitive radioactive methods to determine quantities in the micro and sub-microgram range. The presence of a wide variety of elements, over 40, imposes a very stringent requirement on the method of separation of trace elements from interfering elements, especially from the major components (sodium, chloride, magnesium, and bromine) and others which are prcscnt in comparatively large proportions. Induced activity of an element by thermal neutron bombardment and subsequent determination of the radioactive characteristics of a given element is sensitive as well as sclective. Activation analysis for the quantitative determination of Mn is especially favorable because of the high activation cross section of 13 x 1O-24 cm2 and relatively short half-

Two deep-sea cores from the central Caribbean have been dated by the thorium-230/ protactinium-231 method. The ages obtained are in agreement with the ages previously obtained from other deep-sea cores from the same area. Because of their greater precision, the new dates provide a more accurate time scale for the past 170,000 years.

Uranium analyses of sea‐water samples taken from different locations were carried out by the isotope‐dilution method. Uranium was separated by liquid‐liquid extraction from 2000 ml of sea water, for each determination. The small residue of uranium resulting from the chemical separation was analyzed by mounting it on a tantalum filament and examining the U02+ thermal ions in a Nier six‐inch radius, 60° sector‐type mass spectrometer. The results show a concentration of 3.1 to 3.5 micrograms of uranium per kilogram of sea water, with a uranium/sahnity ratio of 9.0 to 9.8 X 10minus;8.

Suicide Attempts in Children and AdolescentsTwenty cases of attemted suicide in patients aged 7 to 15 years old were analysed. An outstanding number of females (15 girls and 5 boys) in their teens (12 to 15 years) were found in the sample. The most commonly employed method for the attempt was drug ingestion (barbiturates, other psychotropic drugs and anticonvulsants). Only a minority of the patients were at vital risk during or after the attempt. In most of them, it was the result of an impulsive action, generally within a disturbed family background (high occurrence of broken parental mariages, alcoholic parents and marital disputes). Less than one half of the subjects admited intentions of serf-destruction. In a certain way most patients were looking for attention from relatives toward their personal problems. (Key words: Suicide Attempts. Children. Adolescents.).Si bien es cierto que la tentativa de suicidio no es frecuente en la ninez y es rara antes de los 10 anos, aumenta considerablemente desde la pubertad y la adolescencia. El suicidio es la cuarta causa de muerte entre los 15 y 19 afios de edad en Francia y EE.UU., despues de los accidentes, homicidios y cancer, y configura la segunda causa de muerte si se amph'a el range de edades entre los 15 y 24 anos 1 . Sin embargo en nuestro medio el problema ha sido poco explorado: salvo por estudios epidemiologicos hechos en adultos 2 . No cncontramos referencias a casos en nifios en nuestro pai's en los ultimos 20 anos. Por este motivo, por el riesgo vital que implica y por constituir, la tentativa de suicidio, un gesto dramatico de demanda de ayuda, presentamos nuestra experiencia en torno a este tema. MATERIAL y METODOSe hizo un analisis retrospective dc 20 casos de tentativa de suicidio atendidos en el Servicio de Neuropsiquiatrfa InfantU del Hospital San Juan de Dies entre Septiembre de 1978 y Junio de 1984, estudiando la edad y sexo de los pacientes, el metodo empleado en el intento, la causa desencadenantc, el caracter premeditado o impulsive de esta, la existencia de riesgo vital, los antecedentes sicopatologicos del paciente, el enjuiciamiento del hecho por paite del nino, la presencm de reincidencias y las caracter isticas del medio familiar. Todos los pacientes fucron cntrevistados por lo menos por_ uno de los autores (E.R.R.) durante plazos variables desde un mes hasta varios anos, aunque tres pacientes solo asistieron a una o dos consultas. Ademas sc obtuvo information de entrevistas con uno de los padres (generalmcnte la madre) o a la persona responsable del nino (abuela o guardadora) en todos los casos. En algunos pacientes se aplicaron examenes psicometricos (W.I.S.C.) y en varios se hicieron visitas domiciliarias por asistentes sociales. RESULTADOSSeis pacientes tenian menos de 12 anos (la manor, de 7 aflos 10 meses), (3 varones), en los otros 14 la edad fluctuaba entre 12 1/12 y 14 3/12 anos en la primera tentativa. La edad en que ocurrieron las reincidencias fluctuaba entre 10 y 15 10/12 anos. Entre los pacientes mayores de 12 anos la proporti...