Studies of thermal conductivity in Fermi-Pasta-Ulam like lattices

The pioneering computer simulations of the energy relaxation mechanisms performed by Fermi, Pasta and Ulam can be considered as the first attempt of understanding energy relaxation and thus heat conduction in lattices of nonlinear oscillators. In this paper we describe the most recent achievements about the divergence of heat conductivity with the system size in 1d and 2d FPU-like lattices. The anomalous behavior is particularly evident at low energies, where it is enhanced by the quasi-harmonic character of the lattice dynamics. Remakably, anomalies persist also in the strongly chaotic region where long--time tails develop in the current autocorrelation function. A modal analysis of the 1d case is also presented in order to gain further insight about the role played by boundary conditions.Comment: Invited article to appear in the Chaos focus issue on "Studies of Nonlinear Problems. I" by Enrico Fermi, John Pasta, and Stanislaw Ulam

I/O: Reinforcing Newsmaking Practices Through Algorithmic Media

Recent developments in communication and information technology have disrupted the long-established dominance of mass media over the production and distribution of news. As an effort to reclaim their role of society’s information gatekeeper, media companies absorb digital technology as instruments of institutional power to reproduce its own logic in the digital space. This paper dis-cusses two interrelated modalities of algorithmic news: economically efficient production, where news outlets utilize quantitative metrics to improve content effectiveness and desirability; and shared-gatekeeping, where visibility and distribution of information are contextual and based on users’ behaviour. The paper proposes that algorithmic media hides under its supposed objectivity and neutrality to become a new gatekeeper “organism”, which not only regulates flows of infor-mation, but also interprets and negotiates both public interests and the value of the news

A multifactorial approach to honeybees health: from multiple causes to consequences and possible actions

In the last decades, large-scale losses of honey bee (Apis mellifera L.) colonies have been recorded all over the world. After years of intense investigation, no specific causal agent for the widespread colony losses has been found but rather a multifactorial origin has been proposed for this syndrome. Biotic and abiotic factors contribute to this phenomenon, but several studies indicate that the ectoparasitic mite Varroa destructor and the Deformed Wing Virus (DWV) play an important role. Recent research has shown that DWV infections at low viral levels are asymptomatic because the honey bee immune competence is able to contain virus replication. As soon as any stress factor interferes with this equilibrium, competing for metabolic resources or negatively acting on immunity, uncontrolled viral replication is promoted, resulting in the transition from a benign covert infection to a devastating overt disease. Xenobiotics, abiotic stressors, malnutrition and other factors can further contribute to complicate the situation. The aim of this thesis was to investigate, at the individual level, how different stress factors and nutrition interact to influence the survival of honey bees. To this aim, we subdivided the study in two phases; in the first one, we assessed how several stress factors as well as pollen influence honey bee health. In a second phase of this study, we investigated how some of these stressors act in combination with the others and in combination with nutrition. We selected seven factors that are possibly implicated in the multifactorial syndrome related to colony losses: pollen, as a natural supply of amino acids and lipids for the honey bee; hydroxymethylfurfural (HMF), a toxic compound contained in additional sugars syrups; acidity, which normally characterizes the sugar syrups mentioned above; nicotine, which is a toxic alkaloid that bees can encounter in the environment and with a mode of action similar to that of neonicotinoid insecticides; a temperature 2-3 degrees below that normally found within the hive; V. destructor, the most dangerous ectoparasite of honey bees and Deformed wing virus (DWV), a key pathogen of honey bees. We confirmed the beneficial effect of pollen nutrition on honey bees as negatively affected by parasites and pathogens. To gain insight into the mechanisms underlying these effects, we interfered with the energetic pathway of mite infested bees using rapamycin, a chemical inhibitor of mTOR, a protein complex that regulates cell growth and other key cellular processes. We observed that rapamycin, just like pollen, decreases DWV load in a manner that could be related to the stimulation of autophagy. More in general, we noted the important role played by nutrition in the interactions between honey bee and other stressors. We also documented for the first time a kind of physiological anorexia triggered by V. destructor infestation, which leads to a reduced energy availability that influences the capacity of honey bees to cope with other stressors. Moreover, we shed light on the possible detrimental side effects of supplementary nutrition administered to bees by beekeepers with homemade sugar syrups. In fact, acidity and HMF that are normally present in such syrups are toxic for honey bees. Lastly, with this work we showed how unpredictable it can be the relationship between stress factors. Since an analytic study of all the factors that can affect honey bee health is unimaginable, the attention should be focused on the metabolic process accounting for the observed interactions in order to develop one or several models that could help to predict the outcome of such interactions

Contabilidad del crecimiento en la República Dominicana 1990-2018: Nueva evidencia

This paper uses fresh data from the Conference Board Total Economy databases to account for the Dominican Republic´s sources of long-run growth in 1990-2018. We adjust for the effects of real business cycles by calculating GDP growth between cyclical maximums and for the quality of production factors and the distinction between ICT capital and NON-ICT capital investment. We find the main factors that explain the GDP rate of growth are, in the order: 1) The Non-ICT Capital, 2) The Labor Quantity, 3) The Total Factor Productivity, followed to a less extent by, the ICT Capital and Labor quality contributions. Indeed, the Total Factor Productivity explains about 10% or less of the total growth on average. This is consistent with the timing and sequencing of structural reforms implemented in Dominican Republic and the recent investments in the most productive sectors.Este documento utiliza datos recientes de las bases de datos de Conference Board Total Economy para dar cuenta de las fuentes de crecimiento a largo plazo de la República Dominicana entre 1990 y 2018. Ajustamos los efectos de los ciclos económicos reales calculando el crecimiento del PIB entre picos cíclicos y controlando la calidad de los factores de producción y la diferencia entre la inversión de capital TIC y No TIC. Encontramos que los principales factores que explican la tasa de crecimiento del PIB son, en el orden: 1) El capital no TIC, 2) La cantidad de trabajo, 3) La productividad total de los factores, seguido en menor medida por, el Capital TIC y las contribuciones de calidad del Trabajo. De hecho, la productividad total de los factores explica aproximadamente el 24% del crecimiento total. Esto es consistente con el momento y la secuencia de las reformas estructurales implementadas en República Dominicana.Fil: Grandes, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Económicas; ArgentinaFil: Frizzera, Franco. Universidad de Buenos Aires. Facultad de Ciencias Económicas; Argentin

ORIGIN OF LIGHT SCATTERING FROM DISORDERED SYSTEMS

Anelastic light scattering is computed numerically for model disordered systems (linear chains and 2-dimensional site and bond percolators), with and without electrical disorder. A detailed analysis of the vibrational modes and of their Raman activity evidences that two extreme mechanisms for scattering may be singled out. One of these resembles scattering from finite size systems, while the other mechanisms originates from spatial fluctuations of the polarizability and is such that modes in even small frequency intervals may have very different Raman activities. As a consequence, the average coupling coefficient $C(\omega)$ is the variance of a zero-average quantity. Our analysis shows that for both linear chains and 2-dimensional percolators the second mechanism dominates over the first, and therefore Raman scattering from disordered systems is essentially due to spatial fluctuations.Comment: 12 pages, Latex, 7 figures available on request

A suspensão do Paraguai no MERCOSUL: problema interno, solução externa

O Paraguai foi suspenso do MERCOSUL após o impeachment do Presidente Fernando Lugo. Como consequência, o último empecilho para a inclusão da Venezuela no bloco – a aprovação por parte do Senado paraguaio – foi superado. A condicionante imposta para o retorno do Paraguai ao bloco é reconhecer a Venezuela como membro. Suspenso por um problema interno, o retorno está sujeito a uma solução externa.  Palavras-Chave: Paraguai; MERCOSUL; Venezuela

Análise de discurso como ferramenta fundamental dos estudos de Segurança – Uma abordagem Construtivista

A Análise de Discurso (AD) é uma ferramenta essencial para os estudos de Segurança nas Relações Internacionais. A proposta desse artigo consiste em fazer uma breve e sucinta discussão sobre a importância dos discursos, tendo como base o chamado Construtivismo Crítico.Palavras-Chaves: Análise de Discurso; Construtivismo; Segurança

A method for continuous sub-annual mapping of forest disturbances using optical time series

Forest disturbances have a major impact on ecosystem dynamics both at local and global scales. Accordingly, it is important to acquire objective information about the location, nature and timing of such events to improve the understanding of their impact, update forest management policies and disturbance mitigation strategies. To this date, remotely sensed data have been widely used for the detection of stand replacing disturbances (SRD) such as windthrows and wildfires. In contrast, less effort has been devoted to the detection of non-stand replacing disturbances (NSRD), typically characterized by slower and gradual temporal dynamics. To address this gap, we propose a method for the automated detection of both SRD and NSRD. The proposed method can detect both past and recent disturbances, with a monthly temporal resolution, in a near real-time fashion by processing new images as they are acquired. Differently from existing approaches that handle the time series as a one-dimensional (1D) temporal trajectory, the method analyzes the sequence of images by organizing them in a two-dimensional (2D) grid-like structure. This representation allows us to model both the intra- and inter-annual variations of the time series taking advantage of the annual cyclical nature of the plant phenology. The method has been tested on study areas attacked by bark beetles achieving a user’s accuracy and producer’s accuracy of 0.91±0.08 and 0.81±0.07 (with 95% confidence intervals) for the disturbed areas, respectively

Mapping a European spruce bark beetle outbreak using sentinel-2 remote sensing data

Insect outbreaks affect forests, causing the deaths of trees and high economic loss. In this study, we explored the detection of European spruce bark beetle (Ips typographus, L.) outbreaks at the individual tree crown level using multispectral satellite images. Moreover, we explored the possibility of tracking the progression of the outbreak over time using multitemporal data. Sentinel-2 data acquired during the summer of 2020 over a bark beetle–infested area in the Italian Alps were used for the mapping and tracking over time, while airborne lidar data were used to automatically detect the individual tree crowns and to classify tree species. Mapping and tracking of the outbreak were carried out using a support vector machine classifier with input vegetation indices extracted from the multispectral data. The results showed that it was possible to detect two stages of the outbreak (i.e., early, and late) with an overall accuracy of 83.4%. Moreover, we showed how it is technically possible to track the evolution of the outbreak in an almost bi-weekly period at the level of the individual tree crowns. The outcomes of this paper are useful from both a management and ecological perspective: it allows forest managers to map a bark beetle outbreak at different stages with a high spatial accuracy, and the maps describing the evolution of the outbreak could be used in further studies related to the behavior of bark beetle

Fatores de risco na mortalidade de pacientes brasileiros hospitalizados com Covid-19: clínicos, sociais, econômicos e regionais

In the year 2020, Brazil occupied third place worldwide in case numbers and second place in deaths from Covid-19. Understanding the factors of risk, social inequality and ethnic health is of paramount importance, according to population multiplicity and its political and economic weaknesses. The context of Brazil has presented gravity in the outbreak, for social and economic factors and its complex racial composition. The objective of this research was to define the risk factors of mortality from patients who need hospitalization during the infection of the Covid-19 virus, based on their economic, social and epidemiological characteristics. Public data of 1,956,350 epidemiological records of Brazilian patients who sought hospital care at the COVID-19 pandemic from February/2020 to May/2021 were used. Descriptive statistics allowed to quantify the impact of the pandemic, demonstrating the differences between regions, ethnicities, ages and the registered comorbidities. For prediction analysis, the logistics regression method was used. The related factors of the patient evolve to death, considering his comorbidities and social factors, primarily his relative income and if illiterate were evaluated. Chances of death are higher among patients with comorbidities, neurological (1.99) and renal (1.97) diseases and immunodeficiency disorders (1.69). While relative income (2,45) indicates that social factors have greater influence on mortality than the studied comorbidities. Patients’ resident in the northern region has a greater chance of mortality than those of the Center-South. We conclude that the socioeconomic circumstances, which were also extremely significant, had a stronger impact on the risks of covid-19 mortality in Brazil during the study period than naturally occurring (neurological, kidney and immunodeficiency diseases). Since more people are susceptible to impoverished circumstances, regional variables in mortality rates are important.No ano de 2020, o Brasil ocupou o terceiro lugar mundial em números de casos e o segundo lugar em mortes por COVID-19. Entender os fatores de riscos, desigualdade social e étnicas em saúde é de suma importância, conforme a multiplicidade populacional e suas fragilidades políticas e econômicas. O contexto do Brasil tem apresentado gravidade no surto, pelos fatores sociais e econômicos e por sua composição racial complexa. O objetivo desta pesquisa foi definir os fatores de risco de mortalidade dos pacientes que necessitam de hospitalização durante a infecção do vírus COVID-19, a partir das suas características econômicas, sociais e epidemiológicas. Foram utilizados dados públicos de 1.956.350 registros epidemiológicos de pacientes brasileiros que procuraram assistência hospitalar na pandemia COVID-19 de fevereiro/2020 a maio/2021. A estatística descritiva permitiu quantificar o impacto da pandemia, demonstrando as diferenças entre regiões, etnias, idades e as comorbidades registradas. Para a análise de predição, foi utilizado o método de regressão logística. Foram avaliados os fatores relacionados de o paciente evoluir para o óbito, considerando suas comorbidades e seus fatores sociais, primordialmente sua renda relativa e se é analfabeto. As chances de morte são maiores entre pacientes com comorbidades, doenças neurológicas (1,99) e renal (1,97) e distúrbios da imunodeficiência (1,69). Enquanto a renda relativa (2,45) indica que os fatores sociais têm maior influência na mortalidade do que as comorbidades estudadas. Os pacientes residentes na região Norte têm maior chance de mortalidade em relação aos do Centro-Sul. Concluímos que as circunstâncias socioeconômicas, que também foram extremamente significativas, tiveram um impacto mais forte nos riscos de mortalidade COVID- 19 no Brasil durante o período do estudo do que as comorbidades que ocorrem naturalmente (doenças neurológicas, renais e de imunodeficiência). Dado que mais pessoas são suscetíveis a circunstâncias empobrecidas, as variáveis regionais nas taxas de mortalidade são importantes