6,504 research outputs found

    The challenge of detecting intracluster filaments with Faraday Rotation

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    The detection of filaments in the cosmic web will be crucial to distinguish between the possible magnetogenesis scenarios and future large polarization surveys will be able to shed light on their magnetization level. In this work, we use numerical simulations of galaxy clusters to investigate their possible detection. We compute the Faraday Rotation signal in intracluster filaments and compare it to its surrounding environment. We find that the expected big improvement in sensitivity with the SKA-MID will in principle allow the detection of a large fraction of filaments surrounding galaxy clusters. However, the contamination of the intrinsic Faraday Rotation of background polarized sources will represent a big limiter to the number of objects that can be significantly detected. We discuss possible strategies to minimize this effect and increase the chances of detection of the cosmic web with the large statistics expected from future surveys.Comment: 16 pages, accepted to Galaxie

    Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis

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    This study investigates the temperature reduction capacity and water consumption of a fan-pad system installed in a greenhouse located in the coastal regions of Almería. The suitability of this system for coastal zones with high environmental humidity during the summer is analyzed. Historical temperature and relative humidity series are studied, obtaining the thermal difference and maximum, medium, and minimum monthly water consumption of the pads based on the operation data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a decrease of 5.92 ºC in the mean temperature and a water consumption of 13.55 l/h per square meter of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel and compared with that of a new pad of the same model. Over time and with low maintenance, the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of the pad increases by 6.6% due to the greater contact time between the air and the waterMinisterio de Economía y Competitividad de España AGL2015-68050-RUnión Europea (FEDER) AGL2015-68050-

    Assessment of the cooling potential of an indoor living wall using different substrates in a warm climate

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    The use of vertical greenery systems in buildings is becoming very popular as they provide several benefits. In this work, the influence of an indoor living wall on the temperature and humidity in a hall inside the School of Agricultural Engineering (University of Seville) was studied. Four different substrates, Geotextile, Epiweb, Xaxim and coconut fibre, were used to grow the plants in order to assess their performance. Several parameters such as temperature, humidity, plant growth or water consumption were monitored and analyzed during a 4-month period. The cooling effect of the living wall was proven, with an average reduction of 4°C over the room temperature though maximum decrements of 6°C have been observed in warmer conditions. Higher air humidity levels were experienced near the living wall, increasing the overall humidity in the room. All the substrates tested were suitable for plant growing and their behaviour was similar. Geotextile showed the best cooling capacity but higher water consumption, coconut fibre presented degradation problems and Epiweb performance was the poorest. Therefore, these systems have been proven to be very useful and interesting for warm indoor environments due to the cooling effect observed in addition to their bio-filtration capacity and the aesthetic component

    Dynamical evolution of magnetic fields in the intracluster medium

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    We investigate the evolution of magnetic fields in galaxy clusters starting from constant primordial fields using highly resolved (≈4 kpc\approx \rm 4 ~kpc) cosmological MHD simulations. The magnetic fields in our sample exhibit amplification via a small-scale dynamo and compression during structure formation. In particular, we study how the spectral properties of magnetic fields are affected by mergers, and we relate the measured magnetic energy spectra to the dynamical evolution of the intracluster medium. The magnetic energy grows by a factor of ∼\sim 40-50 in a time-span of ∼9\sim 9 Gyr and equipartition between kinetic and magnetic energy occurs on a range of scales (<160 kpc< 160 \rm ~kpc at all epochs) depending on the turbulence state of the system. We also find that, in general, the outer scale of the magnetic field and the MHD scale are not simply correlated in time. The effect of major mergers is to shift the peak magnetic spectra to it smaller scales, whereas the magnetic amplification only starts after ≲\lesssim 1 Gyr. In contrast, continuous minor mergers promote the steady growth of the magnetic field. We discuss the implications of these findings in the interpretation of future radio observations of galaxy clusters.Comment: Accepted in MNRAS; 16 pages, 34 figure

    On Rules and Parameter Free Systems in Bounded Arithmetic

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    We present model–theoretic techniques to obtain conservation results for first order bounded arithmetic theories, based on a hierarchical version of the well known notion of an existentially closed model.Ministerio de Educación y Ciencia MTM2005-0865

    Existentially Closed Models and Conservation Results in Bounded Arithmetic

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    We develop model-theoretic techniques to obtain conservation results for first order Bounded Arithmetic theories, based on a hierarchical version of the well-known notion of an existentially closed model. We focus on the classical Buss' theories Si2 and Ti2 and prove that they are ∀Σbi conservative over their inference rule counterparts, and ∃∀Σbi conservative over their parameter-free versions. A similar analysis of the Σbi-replacement scheme is also developed. The proof method is essentially the same for all the schemes we deal with and shows that these conservation results between schemes and inference rules do not depend on the specific combinatorial or arithmetical content of those schemes. We show that similar conservation results can be derived, in a very general setting, for every scheme enjoying some syntactical (or logical) properties common to both the induction and replacement schemes. Hence, previous conservation results for induction and replacement can be also obtained as corollaries of these more general results.Ministerio de Educación y Ciencia MTM2005-08658Junta de Andalucía TIC-13

    Enfermedad de Parkinson y musicoterapia

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    La enfermedad de Parkinson es la segunda enfermedad neurodegenerativa en España producida por una alteración de la sustancia negra del cerebro. Esta afectación da lugar a un déficit de dopamina, causante de la sintomatología de esta enfermedad. Tanto los síntomas motores como los no motores pueden ser tratados mediante un tratamiento farmacológico, logopédico, psicológico y con rehabilitación física, o mediante terapias novedosas como es el caso de la Musicoterapia. El objetivo es mostrar la importancia de intervenciones como la musicoterapia en el tratamiento de la enfermedad de Parkinson. Para lograr dicho objetivo se ha llevado a cabo una búsqueda bibliográfica a través de la cual se ha obtenido información sobre la enfermedad: clínica, etiología, tratamiento, etc y sobre lo que es la musicoterapia y cómo actúa sobre todas las esferas del ser humano. La música contribuye en gran medida en la mejora de los síntomas motores de la enfermedad de Parkinson, pero también logra que las personas que padecen la enfermedad se sientan mejor, permitiendo que se relacionen con otras personas, lo que supone una mejoría de su calidad de vidaOtroGrado en Enfermerí

    Enhancing cognition before clinical symptoms of dementia.

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    As the title of the special issue indicates, controversy surrounds augmentation of brain cognition in humans. Lacking efficacious drugs for Alzheimer's disease (AD) and with many AD patients recruited for clinical trials that unfortunately do not provide the expected results, one wonders whether to test cognition enhancement strategies in individuals without symptoms of cognition decline. This opinion article presents the view that safe drugs and or dietary supplements should be tested worldwide in aged individuals under the control of a non-for-profit organization

    On the quantifier complexity of Δ n+1 (T)– induction

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    In this paper we continue the study of the theories IΔ n+1 (T), initiated in [7]. We focus on the quantifier complexity of these fragments and theirs (non)finite axiomatization. A characterization is obtained for the class of theories such that IΔ n+1 (T) is Π n+2 –axiomatizable. In particular, IΔ n+1 (IΔ n+1 ) gives an axiomatization of Th Π n+2 (IΔ n+1 ) and is not finitely axiomatizable. This fact relates the fragment IΔ n+1 (IΔ n+1 ) to induction rule for Δ n+1 –formulas. Our arguments, involving a construction due to R. Kaye (see [9]), provide proofs of Parsons’ conservativeness theorem (see [16]) and (a weak version) of a result of L.D. Beklemishev on unnested applications of induction rules for Π n+2 and Δ n+1 formulas (see [2]).Ministerio de Educación y Cultura DGES PB96-134
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