355 research outputs found

    Localization and blow-up of thermal waves in nonlinear heat conduction with peaking

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    The authors consider the initial-boundary value problem for the porous medium equation ut =(um)xx in (0,∞)×(0,T), where m>1, 00}as t↑T under the hypothesis that ψ(t)↑∞ as t↑T is investigated. The effect of localization of the blowing-up boundary function when lim sup t↑T ζ(t)<∞ is investigated. It is established that localization occurs if and only if lim sup t↑T (∫ t 0 ψ m (s)ds)/ψ(t)<∞, and some estimates concerning the asymptotic behaviour of the solution near the singular point t=T and in the blow-up set Ω={x≄0: lim sup t↑T u(x,t)=∞} are given. Various estimates from above and below on the length ω=supΩ of the blow-up set are obtained. These theorems make more precise some previous results concerning the localization of the boundary blowing-up function which were given in the book by A. A. SamarskiÄ­, the reviewer et al. [Peaking modes in problems for quasilinear parabolic equations(Russian), "Nauka'', Moscow, 1987]. Proofs of the theorems are based on comparison with some explicit solutions and on construction of different kinds of weak sub- and supersolutions. The authors use some special integral identities and estimates of the solution and its derivatives by means of the maximum principle. A special comparison theorem above blow-up sets for different boundary functions is proved

    Investor inattention to all-cash acquisition announcements: a joint day-time analysis in the Spanish market

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    Prior studies suggest that investors have limited attention, which determines the speed with which information is incorporated into share prices and, in turn, affects the efficiency of the markets. Unlike other corporate events, the information contained in an acquisition announcement is generally less standard and more complicated to process. Therefore, investor inattention is less likely around this event. In this study we test the existence of investor inattention for a sample of all-cash acquisition announcements of listed and unlisted target firms released by listed Spanish firms from 1998 to 2018. Cash acquisitions allow us to control for the strategic behavior of overvalued companies engaged in stock-financed acquisitions. We perform a joint analysis of day of the week and time of trade from both a univariate and a multivariate perspective, after controlling for several factors that are related to the market reaction to acquisition announcements. Consistent with the notion that investors are less attentive to Friday announcements, we find a significant lower market reaction to acquisition announcements released during market trading hours both in terms of price and trading volume

    Sensor-based assessment of soil salinity during the first years of transition from flood to sprinkler irrigation

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    A key issue for agriculture in irrigated arid lands is the control of soil salinity, and this is one of the goals for irrigated districts when changing from flood to sprinkling irrigation. We combined soil sampling, proximal electromagnetic induction, and satellite data to appraise how soil salinity and its distribution along a previously flood-irrigated field evolved after its transformation to sprinkling. We also show that the relationship between NDVI (normalized difference vegetation index) and ECe (electrical conductivity of the soil saturation extracts) mimics the production function between yield and soil salinity. Under sprinkling, the field had a double crop of barley and then sunflower in 2009 and 2011. In both years, about 50% of the soil of the entire studied field— 45 ha—had ECe &lt; 8 dS m-1i.e., allowing barley cultivation, while the percent of surface having ECe = 16 dS m-1 increased from 8.4% in 2009 to 13.7% in 2011. Our methodology may help monitor the soil salinity oscillations associated with irrigation management. After quantifying and mapping the soil salinity in 2009 and 2011, we show that barley was stunted in places of the field where salinity was higher. Additionally, the areas of salinity persisted after the subsequent alfalfa cropping in 2013. Application of differential doses of water to the saline patches is a viable method to optimize irrigation water distribution and lessen soil salinity in sprinkler-irrigated agriculture

    VariaciĂłn anual de esporas en el aire de la ciudad de Palencia, de 1990 a 1992

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    The Role of Journey Purpose in Road Traffic Injuries: A Bayesian Network Approach

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    Road traffic injuries are now regarded as the eighth leading cause of death globally. For example, in 2016, 102,362 traffic injuries took place in Spain in which 174,679 drivers suffered injuries. These findings necessitated the development of the current study which focuses on the prime factors that cause this type of injuries. The aim of this study, therefore, is to explore the behavioral factors that entail a higher risk of suffering either a serious or a fatal injury for drivers. Methods. The findings are based on information and data provided by “Dirección General de Tráfico” (DGT) in Spain on traffic injuries that occurred in the year 2016. Reviewing a wide range of the literature, the authors identified the most influential variables and created a model using the Bayesian networks. The variables that define the model are grouped into four factors: vehicle factor, road factor, circumstantial factor and human factor. Results. The results suggest that the principal variables that determine a higher probability of serious or fatal injuries in traffic injuries are: lack of using appropriate safety accessories, high-speed violations, distractions as well as errors. Finally, the research shows the severity probability based on reason of displacement (“in itinere,” on business, or in leisure)

    No AGN evidence in NGC 1614 from deep radio VLBI observations

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    We present deep dual-band 5.0- and 8.4-GHz European VLBI Network (EVN) observations of NGC 1614, a local luminous infrared galaxy with a powerful circumnuclear starburst ring, and whose nuclear engine origin is still controversial. We aim at detecting and characterizing compact radio structures both in the nuclear region and in the circumnuclear ring. We do not find any compact source in the central 200 pc region, setting a very tight 5s upper limit of 3.7 × 1036 and 5.8 × 1036 erg s-1, at 5.0 and 8.4 GHz, respectively. However, we report a clear detection at both frequencies of a compact structure in the circumnuclear ring, 190 pc to the north of the nucleus, whose luminosity and spectral index are compatible with a core-collapse supernova, giving support to the high star formation rate in the ring. Our result favours the pure starburst scenario, even for the nucleus of NGC 1614, and shows the importance of radio VLBI (very long baseline interferometry) observations when dealing with the obscured environments of dusty galaxies

    Attractive and repulsive interactions in the inelastic scattering of NO by Ar: A comparison between classical trajectory and close-coupling quantum mechanical results

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    The rotationally inelastic scattering of NO by Ar was studied on a potential energy surface at the collision energy of a high resolution experiment. The study entailed the calculationm of the state-resolved integral and differential cross sections for all the excited levels of NO in the lowest spin-orbit manifold. The quasiclassical approach was shown to satisfactorily reproduce few observations seen in both the experimental and quantum mechanical state-resolved differential cross-sections. © 2003 American Institute of PhysicsFunded by the Ministry of Science and Technology of Spain under Grants No. BQU2002-04627-C02 and No. REN 2000-1557, by the European Union through the RTN Reaction Dynamics ~HPRN-CT-1999-0007!, and by the U.S. National Science Foundation ~Grant No. CHE-9971810! The research was performed within the Unidad Asociada ‘‘QuĂ­mica FĂ­sica Molecular’’ between the Universidad Complutense and the CSIC.Peer Reviewe

    Novel Ir1–xCoxO2 thin films: Growth and characterization

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    Ir1–xCoxO2 thin films have been prepared by reactive co–sputtering deposition at room temperature. Composition, structure, electronic properties and electric and magnetic behavior have been analyzed by different techniques including XRR, XRD, TEM microscopy, SQUID magnetometry, electrical resistivity and XAS spectroscopy. After annealing, an Ir1–xCoxO2 substitutional solid solution phase with rutile crystal structure was achieved for a wide Co-doping range 0 ≀ x ≀ 0.6. Starkly departing from the highly insulating behavior of CoO and Co3O4, the electrical resistivity at room temperature of our films is only slightly higher than that of IrO2. Likewise, our work shows that the magnetic response of the doped films is very similar to that of the paramagnetic parent IrO2. Neither ferromagnetism nor enhanced paramagnetism is observed. XAS spectra indicate a Co3+ oxidation state and, correspondingly, an oxidation state of ∌5+ for Ir ions in the polycrystalline Ir0.6Co0.4O2 film. By application of sum rules, a 13 % increase in the spin–orbit coupling is found despite the lattice shrinkage causes a detrimental bandwidth broadening

    Data on the working population in Spain related to training, workplace conditions and accident rates

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    Obtaining data on worker accident rates is necessary in order to analyze the causes and variables involved in the occurrence of said accidents. The majority of these data, collected after the accident occurs, do not consider the employee's working conditions. Here are presented the data on workplace accidents and the conditions of the workers by analyzing the generic data supplied as part of the 7th National Survey of Workplace Conditions (EWCS) in Spain, conducted in 2011. These data will yield the variables needed to determine if the information on workplace risks provided by the survey respondents has an appreciable effect on the occurrence of occupational accidents in the working population, and will also be used to explore other variables

    Renormalizing Partial Differential Equations

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    In this review paper, we explain how to apply Renormalization Group ideas to the analysis of the long-time asymptotics of solutions of partial differential equations. We illustrate the method on several examples of nonlinear parabolic equations. We discuss many applications, including the stability of profiles and fronts in the Ginzburg-Landau equation, anomalous scaling laws in reaction-diffusion equations, and the shape of a solution near a blow-up point.Comment: 34 pages, Latex; [email protected]; [email protected]
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