On some properties of the asymptotic Samuel function

The asymptotic Samuel function generalizes to arbitrary rings the usual order function of a regular local ring. Here we explore some natural properties in the context of excellent, equidimensional rings containing a field. In addition, we establish some results regarding the Samuel Slope of a local ring. This is an invariant related with algorithmic resolution of singularities of algebraic varieties. Among other results, we study its behavior after certain faithfully flat extensions.Comment: 21 page

Hydrological and erosion response at micro-plot to -catchment scale following forest wildfire, north-central Portugal

Wildfires can have important impacts on hydrological and soil erosion processes, due to the destruction of vegetation cover and changes to soil properties. According to Shakesby and Doerr (2006), these wildfire effects are: i) much better known at small spatial scales (especially erosion plots) than at the scale of catchments; ii) much better studied with respect to overland flow and streamflow (and, then, especially peak discharges) than to soil erosion. Following up on a precursor project studying runoff generation and the associated soil losses from micro-plot to slope-scale in Portuguese eucalypt forests, the EROSFIRE-II project addresses the connectivity of these processes across hillslopes as well as within the channel network. This is done in the Colmeal study area in central Portugal, where the outlet of an entirely burnt catchment of roughly 10 ha was instrumented with a gauging station continuously recording water level and tubidity, and five slopes were each equipped with 4 runoff plots of < 0,5 m2 (“micro-plot”) and 4 slope-scale plots as well as 1 slope-scale sediment fence. Starting one month after the August 2008 wildfire, the plots were monitored at 1- to 2-weekly intervals, depending on the occurrence of rainfall. The gauging station became operational at the end of November 2008, since the in-situ construction of an H-flume required several weeks. A preliminary analysis of the data collected till the end of 2008, focusing on two slopes with contrasting slope lengths as well as the gauging station: revealed clear differences in runoff and erosion between: (i) the micro-plot and slope-scale plots on the same hillslope; (ii) the two slopes; (iii) an initial dry period and a subsequent much wetter period; (iv) the slopes and the catchment-scale, also depending on the sampling period. These results suggest that the different processes govern the hydrological and erosion response at different spatial scales as well as for different periods, with soil water repellency playing a role during the initial post-fire period. The current presentation will review these preliminary results based on the data collected during the first year after the wildfire

Differences in ATP generation via glycolysis and oxidative phosphorylation, and relationships with sperm motility, in mouse species

Mouse sperm produce enough ATP to sustain motility by anaerobic glycolysis and respiration. However, previous studies indicated that an active glycolytic pathway is required to achieve normal sperm function, and identified glycolysis as the main source of ATP to fuel the motility of mouse sperm. All the available evidence has been gathered for the lab mouse, while comparative studies including closely related mouse species have revealed (a) a wide range of variation in sperm motility and ATP production, and (b) that the lab mouse shows comparatively low values in these traits. In this study, we compared the relative reliance on the usage of glycolysis or oxidative phosphorylation as ATP sources for sperm motility between mouse species that exhibit significantly different sperm performance parameters. We found that the sperm of species with higher oxygen consumption/lactate excretion rate ratio were able to produce higher amounts of ATP, achieving higher swimming velocities. Additionally, we show that the species with higher respiration/glycolysis ratio have a higher degree of dependence upon active oxidative phosphorylation. Moreover, we characterize for the first time, two mouse species in which sperm depend on functional oxidative phosphorylation to achieve normal performance. Finally, we discuss that sexual selection through sperm competition could promote adaptations in sperm energetic metabolism tending to increase the usage of oxidative phosphorylation in relation to glycolysis, as this would constitute a more efficient pathway for the generation of ATP (and faster sperm).Peer reviewe

Three-Dimensional Propagation of Magnetohydrodynamic Waves in Solar Coronal Arcades

We numerically investigate the excitation and temporal evolution of oscillations in a two-dimensional coronal arcade by including the three-dimensional propagation of perturbations. The time evolution of impulsively generated perturbations is studied by solving the linear, ideal magnetohydrodynamic (MHD) equations in the zero-beta approximation. As we neglect gas pressure the slow mode is absent and therefore only coupled MHD fast and Alfven modes remain. Two types of numerical experiments are performed. First, the resonant wave energy transfer between a fast normal mode of the system and local Alfven waves is analyzed. It is seen how, because of resonant coupling, the fast wave with global character transfers its energy to Alfvenic oscillations localized around a particular magnetic surface within the arcade, thus producing the damping of the initial fast MHD mode. Second, the time evolution of a localized impulsive excitation, trying to mimic a nearby coronal disturbance, is considered. In this case, the generated fast wavefront leaves its energy on several magnetic surfaces within the arcade. The system is therefore able to trap energy in the form of Alfvenic oscillations, even in the absence of a density enhancement such as that of a coronal loop. These local oscillations are subsequently phase-mixed to smaller spatial scales. The amount of wave energy trapped by the system via wave energy conversion strongly depends on the wavelength of perturbations in the perpendicular direction, but is almost independent from the ratio of the magnetic to density scale heights.Comment: 27 pages, 11 figure

History-based Self-Organizing Traffic Lights

Managing traffic in cities is nowadays a complex problem involving considerable physical and economical resources. Multi-agent Systems (MAS) consist of a set of distributed, usually co-operating, agents that act autonomously. The traffic in a city can be simulated by a MAS with different agents, cars and traffic lights, that interact to obtain an overall goal: to reduce average waiting times for the traffic users. In this paper, we describe an agent-based simulator to model traffic in cities.Using this simulator, we present a self-organizing solution to efficiently manage urban traffic. We compare our proposal with recent approaches, providing better results than classical and alternative self-organizing methods, with lower resources and investments

Gobernanza global: visiones teóricas y pluralidad de actores

A presente pesquisa tem o objetivo de fazer uma análise teórica sobre o movimento da governança global, através do estudo dos principais atores, articulações e mecanismos alternativos. A metodologia utilizada no trabalho foi revisão bibliográfica de abordagem qualitativa. Teve-se como critério a utilização de literatura clássica, artigos, estudos contemporâneos sobre a temática. A delimitação temporal da pesquisa se deu a partir da década de 1990, devido á ascensão dos processos de globalização após a guerra-fria, da nova ordem multipolar e do recrudescimento do neoliberalismo. Ocorreram assim mudanças nos paradigmas internacionais das relações políticas e econômicas entre atores heterogêneos e plurais –Estados nacionais, empresas multinacionais, sociedade civil global, organizações internacionais, blocos regionais-. Isso ampliou os cenários e espaços de disputa pelo poder. Essas dinâmicas comportam uma pluralidade de atores públicos e privados que disputam espaço e relacionam-se ao mesmo tempo. É nesse cenário de disputa, controle e condução pelo poder que as dinâmicas da governança global são estabelecidas, sem necessariamente um governo mundial constituído e revestido de uma única autoridade. O caráter contraditório e por vezes não explícito da governança global tem apresentado desafios teóricos para qualquer tentativa de entender seu funcionamento e sua evolução.The objective of this research is to carry out a theoretical analysis of the global governance movement through the study of the main actors, articulations and alternative mechanisms. The methodology used in the study was a bibliographical review of a qualitative approach. The criteria included the use of classical literature, articles and contemporary studies on the subject. The temporal delimitation of the research began in the 1990s, due to the rise of globalization processes after the Cold War, with the new multipolar order and the resurgence of neo-liberalism. So many changes occurred in international paradigms of political and economic relations between heterogeneous actors and plurals - nation states, multinational corporations, global civil society, international organizations, regional blocks - that the scenarios and spaces of power struggle expanded. These dynamics involve a plurality of public and private actors competing for space and relating at the same time. It is in this scenario that dispute for and control of the power dynamics of global governance are established, without necessarily a single world government anointed with authority. The contradictory, and sometimes not explicit, character of global governance has presented theoretical challenges for any attempts to understand its operation and its evolution.La presente investigación tiene como objetivo hacer un análisis teórico sobre el movimiento de la gobernanza global a través del estudio de los principales actores, articulaciones y mecanismos alternativos. La metodología utilizada en el trabajo fue revisión bibliográfica de abordaje cualitativa. Se tuvo como criterio la utilización de literatura clásica, artículos, estudios contemporáneos sobre la temática. La delimitación temporal de la investigación se dio a partir de la década de 1990, debido al acenso de los procesos de globalización después de la guerra fría, al nuevo orden multipolar y al recrudecimiento del neoliberalismo. Ocurrieron de esta forma cambios en los paradigmas internacionales de las relaciones políticas y económicas entre actores heterogéneos y plurales –Estados nacionales, empresas multinacionales, sociedad civil global, organizaciones internacionales, bloques regionales.- Eso amplió los escenarios y espacios de disputa por el poder. Esas dinámicas comprenden una pluralidad de actores públicos y privados que disputan espacio y se relacionan al mismo tiempo. Es en ese escenario de disputa, control y conducción por el poder que las dinámicas de la gobernanza global son establecidas, sin necesariamente un gobierno mundial constituido y revestido de una única autoridad. El carácter contradictorio y muchas veces no explícito de gobernanza global ha presentado desafíos teóricos para cualquier intento de entender su funcionamiento y evolución.Instituto de Relaciones Internacionale

Gobernanza global: visiones teóricas y pluralidad de actores

A presente pesquisa tem o objetivo de fazer uma análise teórica sobre o movimento da governança global, através do estudo dos principais atores, articulações e mecanismos alternativos. A metodologia utilizada no trabalho foi revisão bibliográfica de abordagem qualitativa. Teve-se como critério a utilização de literatura clássica, artigos, estudos contemporâneos sobre a temática. A delimitação temporal da pesquisa se deu a partir da década de 1990, devido á ascensão dos processos de globalização após a guerra-fria, da nova ordem multipolar e do recrudescimento do neoliberalismo. Ocorreram assim mudanças nos paradigmas internacionais das relações políticas e econômicas entre atores heterogêneos e plurais –Estados nacionais, empresas multinacionais, sociedade civil global, organizações internacionais, blocos regionais-. Isso ampliou os cenários e espaços de disputa pelo poder. Essas dinâmicas comportam uma pluralidade de atores públicos e privados que disputam espaço e relacionam-se ao mesmo tempo. É nesse cenário de disputa, controle e condução pelo poder que as dinâmicas da governança global são estabelecidas, sem necessariamente um governo mundial constituído e revestido de uma única autoridade. O caráter contraditório e por vezes não explícito da governança global tem apresentado desafios teóricos para qualquer tentativa de entender seu funcionamento e sua evolução.The objective of this research is to carry out a theoretical analysis of the global governance movement through the study of the main actors, articulations and alternative mechanisms. The methodology used in the study was a bibliographical review of a qualitative approach. The criteria included the use of classical literature, articles and contemporary studies on the subject. The temporal delimitation of the research began in the 1990s, due to the rise of globalization processes after the Cold War, with the new multipolar order and the resurgence of neo-liberalism. So many changes occurred in international paradigms of political and economic relations between heterogeneous actors and plurals - nation states, multinational corporations, global civil society, international organizations, regional blocks - that the scenarios and spaces of power struggle expanded. These dynamics involve a plurality of public and private actors competing for space and relating at the same time. It is in this scenario that dispute for and control of the power dynamics of global governance are established, without necessarily a single world government anointed with authority. The contradictory, and sometimes not explicit, character of global governance has presented theoretical challenges for any attempts to understand its operation and its evolution.La presente investigación tiene como objetivo hacer un análisis teórico sobre el movimiento de la gobernanza global a través del estudio de los principales actores, articulaciones y mecanismos alternativos. La metodología utilizada en el trabajo fue revisión bibliográfica de abordaje cualitativa. Se tuvo como criterio la utilización de literatura clásica, artículos, estudios contemporáneos sobre la temática. La delimitación temporal de la investigación se dio a partir de la década de 1990, debido al acenso de los procesos de globalización después de la guerra fría, al nuevo orden multipolar y al recrudecimiento del neoliberalismo. Ocurrieron de esta forma cambios en los paradigmas internacionales de las relaciones políticas y económicas entre actores heterogéneos y plurales –Estados nacionales, empresas multinacionales, sociedad civil global, organizaciones internacionales, bloques regionales.- Eso amplió los escenarios y espacios de disputa por el poder. Esas dinámicas comprenden una pluralidad de actores públicos y privados que disputan espacio y se relacionan al mismo tiempo. Es en ese escenario de disputa, control y conducción por el poder que las dinámicas de la gobernanza global son establecidas, sin necesariamente un gobierno mundial constituido y revestido de una única autoridad. El carácter contradictorio y muchas veces no explícito de gobernanza global ha presentado desafíos teóricos para cualquier intento de entender su funcionamiento y evolución.Instituto de Relaciones Internacionale

Consumers’ preferences and willingness to pay for fish products with health and environmental labels: Evidence from five european countries

Seafood products are important sources of protein and components of a healthy and sustainable diet. Understanding consumers’ preferences for fish products is crucial for increasing fish consumption. This article reports the consumer preferences and willingness to pay (WTP) for different fish species and attributes on representative samples in five European countries (n = 2509): France, Germany, Italy, Spain, and the UK. Consumer choices were investigated for fresh fish in a retail market under hypothetical situations arranged by a labelled choice experiment conducted for seven fish species: Cod, herring, seabass, seabream, salmon, trout, and pangasius. The results show the highest premiums for wild-caught fish than farm-raised alternatives. Ready-to-cook products are generally preferred to whole fish, whereas fish fillet preference is more species-specific. The results show positive premiums for a sustainability label and nutrition and health claims, with high heterogeneity across countries and species. With consumers’ preferences and WTP being largely country-and fish-dependent, businesses (fish companies, retailers, and others) should consider the specific market context and adapt their labelling strategies accordingly. Public authorities campaigns should inform consumers about the tangible benefits related with health and environmental labels