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[en] Understanding past and projected drought patterns across Central America’s ‘Dry Corridor’ (CADC) is crucial for adaptation planning and impact mitigation, especially in small-scale agricultural communities. We analyzed historical and predicted drought patterns in the CADC by calculating Standardized Precipitation Index (SPI) values from local rain gauge records, reanalysis data and a 20-member ensemble of bias-corrected, downscaled CMIP-5 GCMs at both seasonal (3 month) and annual (12 month) scales. Trends in drought frequency, duration, intensity were assessed for three, 30 year future periods compared to historical values. Our results suggest a decrease in mean annual rainfall of 8%–14% in the CADC under moderate to high emissions scenarios, respectively, by end-of-century (2071–2100) relative to a historical baseline (1950–2005). However, projected changes to drought characteristics under these scenarios are more pronounced, with seasonal-scale droughts projected to lengthen by 12%–30%, intensify by 17%–42% and increase in frequency by 21%–24% by end-of-century. Annual-scale, longer-term droughts are projected to lengthen by 68% under moderate emissions, potentially triple in length under high emissions and to intensify by 27%–74%. These results were similar yet slightly more pronounced for some drought metrics when just considering rainy/cropping season months (May–Oct). End-of-century changes to rainfall reliability and drought occurrence such as these would severely impact millions of vulnerable inhabitants in the CADC and should be considered in adaptation policymaking efforts. (letter)
[en] The present study was aimed at carrying out a survey on the knowledge and acceptance level of food irradiation. The work was carried out in Santiago, Chile. As an above-average level country in South and Central America, the results may give an indication about the situation in other countries. The survey could also provide an indication about the impression of the public regarding the international 'Radura' symbol, indicating on a food product that has been irradiated. A total of 497 persons were interviewed. Among the interviewed people, 76.5% did not know that irradiation could be used as a method for food preservation; 46% expressed their belief that irradiated food means the same as radioactive food. Nevertheless, 91% claimed that they would become consumers of irradiated food if they knew that 'irradiated' is not 'radioactive' and that proper irradiation enhances food safety; 95.8% of the interviewed persons were not familiar with the 'Radura' symbol. However, 55.8% expressed their opinion that they would buy irradiated food because of the symbol, affirming that the 'Radura' symbol transmits the sensation of confidence and safety.
[en] The establishment of a nuclear-weapon-free zone in Latin America by means of the Tlatelolco Treaty is one of the finest contributions made by the countries of the region to the political ideal of peace and to international law as applied to disarmament. The history of this Treaty and its main provisions are given in the article introduced
[en] Hepatitis B virus (HBV) exists as 9 major genotypes and multiple subtypes, many of which exhibit differences in pathogenicity and treatment response. Genotype H identified in Central America is associated with low incidence of liver disease and HCC, but higher incidence of occult HBV (low level HBV DNA positivity, HBsAg negative). The replication phenotype of genotype H associated with less severe forms of liver disease is unknown. We hypothesized that the reduced pathogenesis associated with this genotype may be due to by lower rates of viral replication and/or secretion compared to other characterised strains. We used transient transfection and infection cell culture models to characterise the replication phenotype, compared to our D3 reference strain. Genotype H exhibited reduced viral replication and altered envelope protein expression compared to genotype D, with functional studies showing that low replication was in part likely due to sequence differences in the major transcriptional regulatory region.
[en] The paper describes the institutional support to develop projects on renewable energy, also describes the different ways to obtain financial support from the public sector and the interaction among private sector, universities and non governmental agencies in training, research and generation of energy
[en] In spite of the extensive use of fire as an agricultural agent in Central America today, little is known of its history of biomass burning or agriculture. As an indicator of the burning practices on the adjacent land, a sedimentary record of carbonized particles sheds light on the trends in frequency and areal extent of biomass burning. This research focuses on a sediment core recovered from an anoxic site in the Pacific Ocean adjacent to the Central American Isthmus and reports a five-century record of charcoal deposition. The research illustrates that biomass burning has been an important ecological factor in the Pacific watershed of Central America at least during the past five centuries. Fluxes of charcoal have generally decreased toward the present suggesting a reduction in the charcoal source function. Perhaps, five centuries ago, the frequency of biomass burning was greater than it is today, larger areas were burned, or biomass per unit area of burned grassland was greater. The major type of biomass burned throughout this five-century period has been grass, as opposed to woods, indicating that any major deforestation of the Pacific watershed of Central America occurred prior to the Conquest
[en] The studies of Atlantic-Pacific Interoceanic Sea-Level Canal Study Commission are are not as yet completed, although there is no reason at this time to doubt that the 1 December 1970 deadline for the Commission's final report will be met. Since it has not been published, I am unable to pass on to you any of its conclusions; they simply do not exist today. And it would be improper for me to reveal the substance of the Commission's deliberations to date or to speculate upon what their outcome may be. But many elements of the work being conducted under my supervision - The Engineering Feasibility Study - are already in the public domain. It is to them that my remarks here are addressed. Of the six basic routes we have considered in our studies for possible sea-level canal alinements, four could involve nuclear excavating techniques. The so-called nuclear alternatives are Route 8 along the Nicaragua-Costa Rica border, Route 17 across the Darien Isthmus of Panama, Route 23 crossing the Panama-Colombia border and Route 25 across the western tip of Colombia. The conventionally excavated routes are Route 10 west of the Panama Canal Zone and Route 14 along the alinement of the present canal. The engineering studies examine from a technical standpoint the feasibility of constructing these routes and estimate their costs. To accomplish this we have made conceptual designs for canals capable of transiting at least 40,000 vessels annually (and possibly several times that many) and of accommodating ships of up to 250,000 dwt in size. Thus, in terms of basic requirements, all alternatives - conventional and nuclear - have been made comparable. Beginning with the northernmost route, let us now consider the four nuclear alternatives. Route 8 is 137 miles in length. Its maximum elevations are slightly less than 800 feet in the Continental Divide and about 400 feet through the so-called Eastern Divide. The rock to be excavated is primarily volcanic tuff. It is readily apparent that this route is not competitive with other nuclear alternatives because of its location in a relatively well developed, built-up region. Its construction would require the evacuation of more than one-quarter million people from the exclusion area for the duration of nuclear operations and for about a year thereafter. This would almost certainly be politically unacceptable. There would be an additional requirement on shot days for the temporary evacuation of an estimated 30,000 people from high rise buildings in Managua and San Jose to avoid casualties from possible structural collapse caused by ground shock. The magnitude of these problems can be expressed to some degree in terms of the estimated cost of their resolution. In this case, they constitute a major part - $1.7 billion - of the Route 8 construction costs which we estimate to be $3.5 billion