Land cover change explains the increasing discharge of the Paraná River.

Over the past 40 years, the discharge in South America's Paraná River basin has increased despite no evidence of significant rainfall increases in the basin. In this analysis, we show that the observed multi-decadal increase in discharge can be explained by concomitant changes in land cover that have occurred within the basin during this period. Our analysis also indicates that the peak discharge timing may have shifted concurrently from January/February in the 1970s to March in more recent decades. While land-use effect dominantly alters the long-term temporal dynamics of the river discharge over multi-decades, the change in the seasonality of the discharge can be attributable to the combined effect of the land-use and climate variability. This study suggests that the mean annual discharge is likely to change in the other South American River basins where land transformation is currently taking place, and the shift of the month of peak discharge needs to be taken into consideration to forecast the hydropower generation under changing climate and land conversion.

Infecciones genitales por papilomavirus humanos y cancer: Memorandum de una Reunión de la OMS

There is increasing evidence from molecular biology and clinical investigations that infection with specific types of human papillomavirus (HPV) is associated with anogenital cancers, especially cancer of the cervix uteri. Human papillomavirus types 16 and 18 have been found in the majority of servical cancers investigated; specific viral mechanisms appear to be involved in the malignant conversión of these tumours. However, evidence from epidemiological investigations is still inconclusive. Concerted efforst to study the etiology and natural history of lower genital tract neoplasia and its association with HPV, together with the development of vaccines against specific viral types, are needed in order to make it possible in the future to prevent cervical and other anogenital cancers

Case-control studies of the effect of environmental sanitation on diarrhoea morbidity: methodological implications of field studies in Africa and Asia

The problems and prospects in the use of case-control studies to assess the effects of improvements in environmental sanitation on diarrhoea morbidity are discussed on the basis of two field studies. It is concluded that an adequate design is available for assessing the effects of a single improvement on diarrhoeal disease. The estimates of effect appear to be valid and sufficiently precise. For addressing more complex questions of interactions; sample sizes would have to be increased substantially. The experience with two field studies suggests that there is hope that a simpler protocol may be feasible; in which only limited information is collected; in which few home visits are made; and in which analytical techniques are simple. Until more field studies have been conducted definitive conclusions cannot be reached on the applicability of such a simple; rapid and inexpensive approach

Abastecimiento de agua y servicios de saneamiento: su función en la revolución de la supervivencia infantil / Water supply and sanitation services: our function in the revolution the infantile

Se ha afirmado que las inversiones en programas de abastecimiento de agua y saneamiento no deben constituir un elemento principal de la atención primaria de salud porque no son inversiones en salud que resulten eficaces en función de los costos. En este artículo se demuestra que la metodología empleada para llegar a esta conclusión está afectada en forma sistemática por prejuicios en contra del suministro de agua y los servicios de saneamiento; que tales inversiones suelen ser importantes para la salud aun cuando los efectos directos sean modestos; que los efectos a largo plazo son mucho mayores que los efectos a corto plazo y que, a pesar de estos factores, los efectos a corto plazo producidos en la salud por mejoras en el abastecimiento de agua y el saneamiento son, por lo general, considerables

Abastecimiento de agua y servicios de saneamiento : Su funcion en la revolucion de la supervivencia infantil / A role for water supply and sanitation in the child survival revolution

It has been argued that investments in water supply and sanitation should not be a major element of primary health care because these are not cost-effective health investments. This article demonstrates that the methodology used to arrive at this conclusion is systematically biased against water supply and sanitation; that such investments may be important for health even if the direct effects are modest; that the long-run effects; and that, these factors not withstanding, the short-run impacts of water supply and sanitation improvements on health are usually substantial

Infecciones genitales por papilomavirus humanos y cancer: Memorándum de una Reunión de la OMS

There is increasing evidence from molecular biology and clinical investigations that infection with specific types of human papillomavirus (HPV) is associated with anogenital cancers, especially cancer of the cervix uteri. Human papillomavirus types 16 and 18 have been found in the majority of servical cancers investigated; specific viral mechanisms appear to be involved in the malignant conversion of these tumours. However, evidence from epidemiological investigations is still inconclusive. Concerted efforst to study the etiology and natural history of lower genital tract neoplasia and its association with HPV, together with the developement of vaccines against specific viral types, are needed in order to make it possible in the future to prevent cervical and other anogenital cancers