Regional trends and controlling factors of fatal landslides in Latin America and the Caribbean

A new data set of landslides that caused loss of life in Latin America and the Caribbean in the 10-year period from 2004 and 2013 inclusive has been compiled, providing new insight into the impact of landslides in this key part of the world. This data set indicates that in the 10-year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landslides is highly heterogeneous, with areas of high incidence in parts of the Caribbean (most notably Haiti), Central America, Colombia, and southeast Brazil. There is significant interannual variation in the number of landslides, with the El Niño/La Niña cycle emerging as a key control. Our analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. On a national basis we have compared the occurrence of fatality-inducing landslide occurrence with the production of locally authored research articles, demonstrating that there is a landslide research deficit in Latin America and the Caribbean. Understanding better the mechanisms, distribution causes and triggers of landslides in Latin America and the Caribbean must be an essential first step towards managing the hazard

Sample size determination for estimating antibody seroconversion rate under stable malaria transmission intensity

Background In the last decade, several epidemiological studies have demonstrated the potential of using seroprevalence (SP) and seroconversion rate (SCR) as informative indicators of malaria burden in low transmission settings or in populations on the cusp of elimination. However, most of studies are designed to control ensuing statistical inference over parasite rates and not on these alternative malaria burden measures. SP is in essence a proportion and, thus, many methods exist for the respective sample size determination. In contrast, designing a study where SCR is the primary endpoint, is not an easy task because precision and statistical power are affected by the age distribution of a given population. Methods Two sample size calculators for SCR estimation are proposed. The first one consists of transforming the confidence interval for SP into the corresponding one for SCR given a known seroreversion rate (SRR). The second calculator extends the previous one to the most common situation where SRR is unknown. In this situation, data simulation was used together with linear regression in order to study the expected relationship between sample size and precision. Results The performance of the first sample size calculator was studied in terms of the coverage of the confidence intervals for SCR. The results pointed out to eventual problems of under or over coverage for sample sizes ≤250 in very low and high malaria transmission settings (SCR ≤ 0.0036 and SCR ≥ 0.29, respectively). The correct coverage was obtained for the remaining transmission intensities with sample sizes ≥ 50. Sample size determination was then carried out for cross-sectional surveys using realistic SCRs from past sero-epidemiological studies and typical age distributions from African and non-African populations. For SCR < 0.058, African studies require a larger sample size than their non-African counterparts in order to obtain the same precision. The opposite happens for the remaining transmission intensities. With respect to the second sample size calculator, simulation unravelled the likelihood of not having enough information to estimate SRR in low transmission settings (SCR ≤ 0.0108). In that case, the respective estimates tend to underestimate the true SCR. This problem is minimized by sample sizes of no less than 500 individuals. The sample sizes determined by this second method highlighted the prior expectation that, when SRR is not known, sample sizes are increased in relation to the situation of a known SRR. In contrast to the first sample size calculation, African studies would now require lesser individuals than their counterparts conducted elsewhere, irrespective of the transmission intensity. Conclusions Although the proposed sample size calculators can be instrumental to design future cross-sectional surveys, the choice of a particular sample size must be seen as a much broader exercise that involves weighting statistical precision with ethical issues, available human and economic resources, and possible time constraints. Moreover, if the sample size determination is carried out on varying transmission intensities, as done here, the respective sample sizes can also be used in studies comparing sites with different malaria transmission intensities. In conclusion, the proposed sample size calculators are a step towards the design of better sero-epidemiological studies. Their basic ideas show promise to be applied to the planning of alternative sampling schemes that may target or oversample specific age groups

Genetic polymorphism in meat fatty acids in araucano creole sheeps

Meat is a source of proteins and minerals. However, red meats have high levels of saturated fatty acids (SFA) and a low proportion of monounsaturated fatty acids (MUFA), a combination which has been linked to cancer and cardiovascular diseases. In ruminants, there are several genes that regulate the proportions of MUFA in tissues, but the most important is SCD (Stearoyl-CoA desaturase). The polymorphism g.31C >A has been described in the promoter region of the SCD gene, which is associated with changes in the gene expression and MUFA levels in the meat. The aim of this study was to detect the presence of polymorphism g.31C >A in a population of Araucano creole sheep using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Genomic DNA was obtained from 157 Araucano creole sheep. The SCD promoter region was amplified using PCR and the amplicons were digested with restriction enzyme MnlI. The allelic frequency was 0.98 for the C allele and 0.02 for the A allele. The in silico analysis showed that the A allele could alter the expression of SCD. This is the first report of the presence of polymorphism g.31C >A in Chilean sheep, and its association with SCD expression levels and the proportion of MUFA in the meat will require further investigation

Polyphenols and sugars recovery from autohydrolysis of pineapple waste

[Excerpt] The aim of this research was to evaluate the influence of temperature, time and mass/ volume ratio on the release of sugars and polyphenols using an autohydrolysis procedure from pineapple waste. A Box-Bhenken design was used with three factors (time, temperature and mass/volume ratio) and three levels was used. All treatments were performed in triplicate. Nine central points were used. For autohydrlosysis treatments, an oil bath was used [1]. After autohydrolysis, liquid phases or hydrolysates were analyzed for glucose and fructose concentration by high performance liquid chromatography (HPLC) [2]. The FolinCiocalteu assay was used to measure total polyphenols of hydrolysates [3] and HPLC to identify these molecules [4]. (...

Hölder's inequality: some recent and unexpected applications

Holder's inequality, since its appearance in 1888, has played a fundamental role in Mathematical Analysis and may be considered a milestone in Mathematics. It may seem strange that, nowadays, it keeps resurfacing and bringing new insights to the mathematical community. In this survey we show how a variant of Holder's inequality (although well-known in PDEs) was essentially overlooked in Functional/Complex Analysis and has had a crucial (and in some sense unexpected) influence in very recent advances in different fields of Mathematics. Some of these recent advances have been appearing since 2012 and include the theory of Dirichlet series, the famous Bohr radius problem, certain classical inequalities (such as Bohnenblust-Hille or Hardy-Littlewood), and Mathematical Physics

Autohydrolysis extraction of bioactive compounds from pineapple waste

The aim of this research was to evaluate the influence of temperature, time and mass/volume ratio on the release of sugars and polyphenols using an autohydrolysis procedure from pineapple waste and determine its antioxidant activity. A Box-Bhenken design was used with three factors (time, temperature and mass/volume ratio) at three levels. All treatments were performed in triplicate. For autohydrolysis treatments, an oil bath was used [1]. After extraction process, liquid phases or hydrolysates were analyzed for glucose and fructose concentration by high performance liquid chromatography (HPLC) [2]. The Folin-Ciocalteu assay was used to measure total polyphenols of hydrolysates [3] and HPLC to identify these molecules [4]. Free radical scavenging activity (DPPH assay) and radical cation decolorization assay (ABTS) were assayed [5]. Figure 1, shows the antioxidant activity obtained from experimental matrix Box-Bhenken design from autohydrolysis treatments of pineapple waste. It was observed most treatments have higher activity than control, this is due to the abundance of bioactive compounds present in the hydrolysates. Conclusion: Autohydrolysis process is a good alternative for an effective extraction (using water as only reaction medium) of value-added compounds that can be used for alcoholic drinks enriched with natural antioxidants. In addition, this technology is an environmentally friendly extraction alternative in compared with traditional chemical process

Análise e simulações de um filtro banda adaptativo aplicado a um filtro activo série

Neste artigo apresenta-se o trabalho de projecto, simulação, análise e ajuste de parâmetros de um Filtro Banda Adaptativo (FBA), utilizado para, a partir das correntes medidas, gerar um sinal de referência que consiste na componente positiva à frequência fundamental das correntes do sistema trifásico. A necessidade deste sinal de referência deve-se à abordagem seguida no controlo de um Filtro Activo Série. Foram efectuadas várias simulações visando estudar o comportamento do FBA com cargas que originam elevados índices de distorção harmónica e desequilíbrio, nomeadamente rectificadores trifásicos e monofásicos com cargas do tipo RC e RL, sendo consideradas as impedâncias das linhas. As simulações foram efectuadas para diversos valores de ganho do filtro de forma a se observar as tendências de variação das saídas do mesmo.The objective of this paper is to explain the steps taken in the project, simulation, analysis and adjustment of the parameters of an Adaptive Band-Pass Filter used to generate a reference signal, consisting of the direct positive sequence of the fundamental currents of a three-phase system. This signal is required to the control approach of a Series Active Power Filter. Various simulations were performed in order to study the behavioural tendency of the Adaptive Filter. In order to obtain highly distorted current wave-shapes, three phase and single phase rectifiers with RC loads were used. To obtain unbalanced currents different types of loads were used in the single phase rectifiers. For both cases the line impedances were considered. Several simulations were run for different values of the Adaptive Filter gain in order to observe the variation of the Filter outputs.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESE/41170/2001