Structural breaks and long-run trends in commodity prices

The oil shocks of the 1970s, which quadrupled the price of petroleum, marked the end of an abnormal period of price stability and renewed interest in predicting the evolution of commodity prices. But most subsequent studies have focused on the short-run effects of price fluctuations, mainly because they greatly affect the foreign trade of developing countries. Sophisticated compensation mechanisms, such as commodity funds, have been introduced to counterbalance the transitory effects of price shocks. But the long-term evolution of prices also affects policy design and development strategies and may have a more important role in fostering long-run growth. The evidence presented by Prebisch (1950) and Singer (1950) of a secular negative trend in the price of commodities in 1870-1945 implies an increasingly weak position for developing countries relative to industrial economies. This hypothesis by Prebisch and Singer has been strongly debated, both theoretically and empirically, during the past four decades. Using recent advances in econometric theory, the authors analyze the long-run dynamics of the price of the 24 most-traded commodities in 1900-92. The method they use tests for nonstationarity (unit roots) in the series with a technique that allows structural breaks to be endogenously determined. The results show that 15 of the 24 commodity prices present negative trends, six are trendless, and three exhibit positive trends. Thus, the Prebisch-Singer hypothesis though not universal, holds for most commodities. This evidence rejects, to some extent, previous evidence by Cuddington (1992) and others. The authors extend the econometric analysis to determine the persistence of shocks to commodity prices. Knowledge of the persistence of shocks is important when designing counterbalancing policies such as commodity funds. The authors use a nonparametric estimator of persistence (the multiple variance ratio) and find that 19 of the 24 commodity prices present persistence levels substantially lower than previous estimates. This evidence suggests that there may be substantial room for stabilization and price support mechanisms for most commodities.Scientific Research&Science Parks,Environmental Economics&Policies,Economic Theory&Research,Markets and Market Access,Commodities,Environmental Economics&Policies,Economic Theory&Research,Markets and Market Access,Access to Markets,Commodities

Classification, testing and optimization of intrusion detection systems

Modem network security products vary greatly in their underlying technology and architecture. Since the introduction of intrusion detection decades ago, intrusion detection technologies have continued to evolve rapidly. This rapid change has led to the introduction of a wealth of security devices, technologies and algorithms that perform functions originally associated with intrusion detection systems. This thesis offers an analysis of intrusion detection technologies, proposing a new classification system for intrusion detection systems. Working closely with the development of a new intrusion detection product, this thesis introduces a method of testing related technologies in a production environment by outlining and executing a series of denial of service and scan and probe attacks. Based on the findings of these experiments, a series of enhancements to the core intrusion detection product is introduced to improve its capabilities and adapt to modem needs of security products

Topological signature for periodic motion recognition

In this paper, we present an algorithm that computes the topological signature for a given periodic motion sequence. Such signature consists of a vector obtained by persistent homology which captures the topological and geometric changes of the object that models the motion. Two topological signatures are compared simply by the angle between the corresponding vectors. With respect to gait recognition, we have tested our method using only the lowest fourth part of the body's silhouette. In this way, the impact of variations in the upper part of the body, which are very frequent in real scenarios, decreases considerably. We have also tested our method using other periodic motions such as running or jumping. Finally, we formally prove that our method is robust to small perturbations in the input data and does not depend on the number of periods contained in the periodic motion sequence.Comment: arXiv admin note: substantial text overlap with arXiv:1707.0698

Exploring the Factors That Affect World Anti-Doping Code Compliance: An Analysis of Peru’s and Bolivia’s National Anti-Doping Organizations

The purpose of this dissertation was to identify and understand the factors that affect the World Anti-Doping Code compliance of the National Anti-Doping Organizations in Peru and Bolivia. By identifying and understanding these factors, this research may provide useful information on how to strengthen compliance and development strategies. This dissertation used a qualitative basic interpretive design with a sample of anti-doping experts from Peru, Bolivia, and the World Anti-Doping Agency, and a comprehensive document review process. Through coding and thematic analysis of the in-depth interview data and the development of a findings model, three main findings were identified as factors that affect compliance: (1) inadequate anti-doping legislation, resources, and structure; (2) authorities’ limited support and understanding of anti-doping and compliance; and (3) limited understanding of the cultural context, the value of relations, and the potential benefits of sanctions. The data analyzed suggested that the factors that affect compliance are generally heterogenous and context-specific, indicating that the best way to address them requires the implementation of context-based compliance and development strategies. Results indicate that compliance strategy may be strengthened by using different responsive regulatory tactics based on cultural differences and compliance motivations of the World Anti-Doping Code signatories

Study of the preparation process and variation of wall components in chia (Salvia hispanica L.) oil microencapsulation

A study of the microencapsulation process of omega-3 rich oil extracted from chia (Salvia hispanica L.) seeds was carried out, which included a comparative analysis of the microcapsules obtained by the spray- and freeze-drying methods using isolated soy proteins and maltodextrin as wall materials at different proportions. Color characterization of the obtained powders was performed and revealed a darker and yellower appearance of the freeze-dried samples compared with the spray-dried ones. Moisture content was measured for each sample and all presented values around 3.5%. The SEM micrographs revealed that spray-dried microcapsules can occur individually or may form clusters or aggregates, with the particles exhibiting a size range varying from 4 to 10 µm. Encapsulation efficiency was measured, with no significant differences found between drying methods or on varying the proportion of wall components (all samples presented values of aproximately 60%). The oxidative stability of microencapsulated oils under accelerated oxidative conditions revealed protection factors 2-fold higher for all samples. In addition, microencapsulated oil stored under 25 ºC revealed lower hydroperoxide values than those of unencapsulated oil throughout the whole storage test. Finally, oil encapsulated in SPI microcapsules also showed lower HPV values than that of the acceptable limit for virgin and cold-pressed vegetable oils (15 meq. O2/kg oil) during the storage test, while unencapsulated oil attained the acceptable limit in 62 days. This result represents an increase in the time of the oil shelf life of between 30 and 48%.Fil: González, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Martinez, Marcela Lilian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Paredes, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; ArgentinaFil: Leon, Alberto Edel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Ribotta, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentin

SPEA MULTIPLICATA (Mexican Spadefoot). PREDATION

El documento (pdf) incluye dos paginas, la portada de la revista y el texto de la nota cientifica que solo son 4 parrafos, es solo una cuartillawe document a new predator-prey interaction between a neonate Mexican Dusky Rattlesnake (Crotalus triseriatus) and a toad Spea multiplicata.CONACY

Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud

The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual chemical compositions. This may have produced a biased sample of Oort cloud comets in which the most common objects may be rare, particularly those with perihelia well beyond the orbit of the Earth. Within this context, the known Oort cloud comets may not be representative of the full sample. Here, we study the spectral properties in the visible region and the cometary activity of Comet C/2018 F4 (PANSTARRS). We also explore its orbital evolution with the aim of understanding its origin within the context of known minor bodies moving along nearly parabolic or hyperbolic paths. We present observations obtained with the 10.4 m Gran Telescopio Canarias (GTC), derive the spectral class and visible slope of C/2018 F4 and characterise its level of cometary activity. Direct N-body simulations are carried out to explore its orbital evolution. The absolute magnitude of C/2018 F4 is Hr=13.62+/-0.04. Assuming a pV=0.04 its diameter is D<10.4 km. The object presents a conspicuous coma, with a level of activity comparable to those of other comets observed at similar heliocentric distances. Comet C/2018 F4 has a visible spectrum consistent with that of an X-type asteroid, and has a spectral slope S'=4.0+/-1.0 %/1000\AA and no evidence of hydration. The spectrum matches those of well-studied primitive asteroids and comets. The analysis of its dynamical evolution prior to discovery suggests that C/2018 F4 is not of extrasolar origin. Although the present-day heliocentric orbit of C/2018 F4 is slightly hyperbolic, its observational properties and past orbital evolution are consistent with those of a dynamically old comet with an origin in the Oort cloud.Comment: 6 pages, 5 figures. In pres