3,381 research outputs found
A non-perturbative analysis of symmetry breaking in two-dimensional phi^4 theory using periodic field methods
We describe the generalization of spherical field theory to other modal
expansion methods. The main approach remains the same, to reduce a
d-dimensional field theory into a set of coupled one-dimensional systems. The
method we discuss here uses an expansion with respect to periodic-box modes. We
apply the method to phi^4 theory in two dimensions and compute the critical
coupling and critical exponents. We compare with lattice results and
predictions via universality and the two-dimensional Ising model.Comment: 12 pages, 4 figures, version to appear in Physics Letters
Physiological responses in a simulated canarian wrestling contest
La Lucha Canaria (LC) ha sido recientemente reconocida como deporte por el Consejo Superior de Deportes, aunque su origen se pierde en el tiempo. Sin embargo, no hay ningún trabajo en la bibliografía científica que describa qué ocurre fisiológicamente durante la competición en esta modalidad de lucha, y éste es el objetivo del presente trabajo. Con una muestra de 12 luchadores de alto nivel (puntales) simulamos el sistema de competición actual en Lucha Canaria. Se estudió la frecuencia cardiaca, la tensión arterial y la concentración de lactato en sangre en diferentes momentos de la simulación. Los patrones observados de respuesta de FC, TA y lactato, caracterizan a la competición en LC como un ejercicio intermitente, con picos de intensidad que superan el umbral láctico y determinan incrementos importantes de FC y TA sistólica. Este estudio es el primero en que se valora la respuesta fisiológica del luchador canario en competición.The aim of this article is to describe what happens from a physiological point of view in a Canarian Wrestling (CW) contest. The Spanish National Sports Council recognized Canarian Wrestling as a sport on June 1st, 2009, although its origin is not very well documented. No scientific article exists in the scientific literature to describe what happens physiologically during a CW contest. Twelve high level wrestlers were recruited to simulate a CW match. The study involved data about heart rate (HR), blood pressure (BP) and blood lactate levels (L) at different moments of the combat. The conclusions of the data observed concerning HR, BP and L classify Canarian Wrestling as an intermittent exercise, with intensity peaks that exceed the lactic threshold and high levels of HR and systolic BP. This is the first paper in which the physiological responses in a Canarian Wrestling competition are reported
Poisson-Jacobi reduction of homogeneous tensors
The notion of homogeneous tensors is discussed. We show that there is a
one-to-one correspondence between multivector fields on a manifold ,
homogeneous with respect to a vector field on , and first-order
polydifferential operators on a closed submanifold of codimension 1 such
that is transversal to . This correspondence relates the
Schouten-Nijenhuis bracket of multivector fields on to the Schouten-Jacobi
bracket of first-order polydifferential operators on and generalizes the
Poissonization of Jacobi manifolds. Actually, it can be viewed as a
super-Poissonization. This procedure of passing from a homogeneous multivector
field to a first-order polydifferential operator can be also understood as a
sort of reduction; in the standard case -- a half of a Poisson reduction. A
dual version of the above correspondence yields in particular the
correspondence between -homogeneous symplectic structures on and
contact structures on .Comment: 19 pages, minor corrections, final version to appear in J. Phys. A:
Math. Ge
The Variable Scale Evacuation Model (VSEM): a new tool for simulating massive evacuation processes during volcanic crises
Volcanic eruptions are among the most awesome and powerful displays of nature's force, constituting a major natural hazard for society (a single eruption can claim thousands of lives in an instant). Consequently, assessment and management of volcanic risk have become critically important goals of modern volcanology. Over recent years, numerous tools have been developed to evaluate volcanic risk and support volcanic crisis management: probabilistic analysis of future eruptions, hazard and risk maps, event trees, etc. However, there has been little improvement in the tools that may help Civil Defense officials to prepare Emergency Plans. Here we present a new tool for simulating massive evacuation processes during volcanic crisis: the Variable Scale Evacuation Model (VSEM). The main objective of the VSEM software is to optimize the evacuation process of Emergency Plans during volcanic crisis. For this, the VSEM allows the simulation of an evacuation considering different strategies depending on diverse impact scenarios. VSEM is able to calculate the required time for the complete evacuation taking into account diverse evacuation scenarios (number and type of population, infrastructure, road network, etc.) and to detect high-risk or "blackspots" of the road network. The program is versatile and can work at different scales, thus being capable of simulating the evacuation of small villages as well as huge cities
Variation of the Chlorophyll a Related to Sea Surface Temperature, Wind and Geostrophic Currents in the Cape Verde Region Using Satellite Data
We present a comparative analysis of satellite derived climatologies in the Cape Verde
region (CV). In order to establish chlorophyll a variability, in relation to other oceanographic
phenomena, a set of, relatively long (from five to eight years), time series of chlorophyll a, sea
surface temperature, wind and geostrophic currents, were ensembled for the Eastern Central
Atlantic (ECA). We studied seasonal and inter-annual variability of phytoplankton concentration,
in relation to the rest of the variables, with a special focus in CV. We compared the situation within
the archipelago with those of the surrounding marine environments, such as the North West African
Upwelling (NWAU), North Atlantic Subtropical Gyre (NASTG), North Equatorial Counter Current
(NECC) and Guinea Dome (GD). At the seasonal scale, CV region behaves partly as the
surrounding areas, nevertheless, some autochthonous features were also found. The maximum peak
of the pigment having a positive correlation with temperature is found at the end of the year for all
the points in the archipelago; a less remarkable rise with negative correlation is also detected in
February for points CV2 and CV4. This is behavior that none of the surrounding environments
have shown. This enrichment was found to be preceded by a drastic drop in wind intensity (SW
Monsoon) during summer months. The inter-annual analysis shows a tendency for decreasing of
the chlorophyll a concentration.Utilizando séries temporais (entre cinco e oito anos) de dados de satélite a grande escala
para a zona de Cabo Verde (CV), faz-se uma análise da variabilidade da clorofila a relacionando-a
com outros parâmetros oceanográficos como a temperatura superficial do mar, o vento e as
correntes geostróficas. Estuda-se a variabilidade estacional e interanual da concentração do
fitoplancton em relação ao resto das variáveis comparando a situação nas águas de Cabo Verde
com o ambiente marinho à volta do arquipélago como o Upwelling Nordeste Africano (NWAU), o
Giro Subtropical Norte-Atlântico (NASTG), a Contra Corrente Norte-Equatorial (NECC) e o Domo
da Guiné (GD). À escala estacional, a zona de Cabo Verde comporta-se como parte das regiões
envolventes, no entanto, algumas características autóctonas foram também encontradas. O pico
máximo do pigmento mostrando uma correlação positiva com a temperatura foi encontrado no final
do ano em todos os pontos eulerianos definidos para o arquipélago; um incremento menos notável,
e com uma correlação negativa, também é detectada nos pontos CV2 e CV4. Este comportamento
não foi visto em nenhum dos pontos do ambiente circundante ao arquipélago. O enriquecimento no
final do ano foi precedido por um drástico decréscimo na intensidade do vento (Monsão do SW)
durante os meses de verão. A análise interanual mostra uma tendência para o decréscimo da
concentração da clorofila a
Kirillov structures and reduction of Hamiltonian systems by scaling and standard symmetries
In this paper, we discuss the reduction of symplectic Hamiltonian systems by
scaling and standard symmetries which commute. We prove that such a reduction
process produces a so-called Kirillov Hamiltonian system. Moreover, we show
that if we reduce first by the scaling symmetries and then by the standard ones
or in the opposite order, we obtain equivalent Kirillov Hamiltonian systems. In
the particular case when the configuration space of the symplectic Hamiltonian
system is a Lie group G, which coincides with the symmetry group, the reduced
structure is an interesting Kirillov version of the Lie-Poisson structure on
the dual space of the Lie algebra of G. We also discuss a reconstruction
process for symplectic Hamiltonian systems which admit a scaling symmetry. All
the previous results are illustrated in detail with some interesting examples
A general framework for nonholonomic mechanics: Nonholonomic Systems on Lie affgebroids
This paper presents a geometric description of Lagrangian and Hamiltonian
systems on Lie affgebroids subject to affine nonholonomic constraints. We
define the notion of nonholonomically constrained system, and characterize
regularity conditions that guarantee that the dynamics of the system can be
obtained as a suitable projection of the unconstrained dynamics. It is shown
that one can define an almost aff-Poisson bracket on the constraint AV-bundle,
which plays a prominent role in the description of nonholonomic dynamics.
Moreover, these developments give a general description of nonholonomic systems
and the unified treatment permits to study nonholonomic systems after or before
reduction in the same framework. Also, it is not necessary to distinguish
between linear or affine constraints and the methods are valid for explicitly
time-dependent systems.Comment: 50 page
On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands
The island of Tenerife (Canary Islands, Spain), is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain), and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaña Blanca) about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic) on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called 'forecast gain' measures (and for the first time quantitatively) what is gained in probabilistic terms by applying the (automatic) failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-)Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this 'forecast gain' in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic
CO2 emissions and energy technologies in Western Europe
In this paper, we investigate the path to the green transition in Europe. In so doing, we implement an empirical model of dynamic panel data on a sample of sixteen Western European countries over the period 1980 to 2019. The model is consistent withvariousfeaturesofneoclassicalgrowththeoryincorporatingenergyuse.Ourfocus is on the short-run determinants of carbon emissions within that set of countries. We provide evidence that the relationship between economic activity and CO2 emissions is strong in economies where economic booms depend on energy-intensive sectors. Also,themitigatingroleofrenewableenergytechnologiesiskeywhenenergyintensity rebounds. These circumstances may constitute a challenge for the climate transition goals targeted in the EU’s Recovery Plan, whose main objective at this very moment is to mitigate the economic and social impact of the coronavirus pandemic.Wethank Pau Pujolas, Jesús Rodríguez-López and Jesús Ruiz for helpful comments, and seminar participants at ICAE-UCM and Universidad de Cantabria. We also thank two anonymous referees and the editors for multiple suggestions. We acknowledge the Spanish Ministry of Science and Innovation (Grant PID2019-107161GB) for financial support
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