359 research outputs found

    Effects of the second virial coefficient on the adiabatic lapse rate of dry atmospheres

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    We study the effect of the second virial coefficient on the adiabatic lapse rate of a dry atmosphere. To this end, we compute the corresponding adiabatic curves, the internal energy, and the heat capacity, among other thermodynamic parameters. We apply these results to Earth, Mars, Venus, Titan, and the exoplanet G1 851d, considering three physically relevant virial coefficients in each case: the hard-sphere, van der Waals, and the square-well potential. These examples illustrate under which atmospheric conditions the effect of the second virial coefficient is relevant. Taking the latter into account yields corrections towards the experimental values of the lapse rates of Venus and Titan in some instances.Comment: 12 pages, 8 figures. Comments are welcom

    Adiabatic lapse rate of real gases

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    We derive a formula for the dry adiabatic lapse rate of atmospheres composed of real gases. We restrict our study to those described by a family of two-parameter cubic equations of state and the recent Guevara-Rodríguez noncubic equation. Since our formula depends on the adiabatic curves, we compute them all at once, considering molecules that can move, rotate, and vibrate, for any equation of state. To illustrate our results, we estimate the lapse rate of the troposphere of Titan, obtaining a better approximation to the observed data in some instances, when compared to the estimation provided by the virial expansion up to the third order.B.D. acknowledges support from the CONEX-Plus programme funded by the Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie Grant No. 801538. J.E.R. acknowledges financial support from the Consejo de Ciencia y Tecnología del Estado de Puebla. This work has been supported by the Spanish Ministerio de Ciencia Innovación y Universidades-Agencia Estatal de Investigación under Grant No. PID2020-116567GB-C22

    Evaluation of the biodiversity in Bryophytes and Pteridophytes in Nueva’s river basin (Llanes, Asturias, North Iberian Peninsula): scientific grounds for its protection and conservation

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    El valle del río de Nueva, orientado al este, se encuentra muy próximo al mar Cantábrico. Su cuenca alta y media, con una superficie de 5,5 Km2, presenta una elevada biodiversidad de briófitos al haberse identificado 145 taxones (85 musgos, 59 hepáticas y 1 antocerota), lo que representa el 23% de la flora briofítica de Asturias. El muestreo realizado, por cuadrículas UTM de 0,5 Km de lado, nos revela también la riqueza en briófitos de este territorio, ya que se han contabilizado hasta 70 taxones distintos en cada unidad de cuadrícula. Del catálogo elaborado resultan ser novedad para la Península Ibérica Dicranodontium asperulum y, además, para el Principado de Asturias, los musgos: Dicranum scottianum y Plagiothecium platyphyllum, y las hepáticas: Bazzania trilobata var. depauperata, Cephalozia crassifolia, Cephalozia loitlesbergeri, Kurzia sylvatica, Lepidozia cupressina, Nowellia curvifolia y Jungermannia paroica, taxa, la mayoría, de reducida distribución. Se amplía el área de distribución, a escala regional, de otras especies (15 hepáticas y 5 musgos) raras o amenazadas, incluidas en la «Red List of Bryophytes of the Iberian Peninsula» (Sérgio & al. 1994). Se ha realizado un estudio fitosociológico de las comunidades briopteridofíticas, en especial las presididas por helechos de carácter «subtropical» presentes en el área de estudio: Woodwardia radicans, Hymenophyllum tunbrigense, Culcita macrocarpa, Stegnogramma pozoi, Vandenboschia speciosa, etc. En su mayoría, estas comunidades pertenecen a la alianza Hymenophyllion tunbrigensis (Orden Anomodonto-Polypodietalia, Clase Anomodonto-Polypodietea), que agrupa fitocenosis constituidas, fundamentalmente, por briófitos y pteridófitos, que colonizan repisas de peñascos, muros y taludes terrosos compactos sobre una delgada capa de tierra (exocomófitos), desarrolladas en ambientes saturados de humedad ambiental, bajo el dosel de formaciones forestales. Mediante el cálculo de los índices de rareza específica, coeficiente de diversidad fitocenótica y calidad botánica, entre otros, se ha evaluado el territorio con el fin de sentar las bases científicas para su protección y conservación.Nueva’s River Valley lies close to the Cantabrico sea, facing towards the east. The upper and middle part of its basin, with a surface of 5.5 Km2, shows a high diversity of bryophytes, as we have identified 145 taxa (85 mosses, 59 liverworts and 1 hornworts), which represent 23% of the Asturias bryophytic flora. The use as sampling unit UTM squares of 0.5 Km side, shows also the richness in bryophytes of this place, as we have found up to 70 different taxa in each square unit. From the catalogue made, Dicranodontium asperulum turns out to be new for the Iberian Peninsula, as in the same way for Principado de Asturias are the mosses Dicranum scottianum and Plagiothecium platyphyllum, and the liverworts Bazzania trilobata var. depauperata, Cephalozia crassifolia, Cephalozia loitlesbergeri, Kurzia sylvatica, Lepidozia cupressina, Nowellia curvifolia and Jungermannia paroica. Most of these taxa have very reduced distribution area. At the regional level, our data represent to enlarge the area of some other rare or threatened species (15 liverworts and 5 mosses), included in the «Red List of Bryophytes of the Iberian Peninsula» (Sérgio & al. 1994). A phytosociologic study of the bryo-pteridophytic communities has been made, especially on those dominated by ferns bearing «subtropical» character: Woodwardia radicans, Hymenophyllum tunbrigense, Culcita macrocarpa, Stegnogramma pozoi, Vandenboschia speciosa, etc. Most of these communities belong to the alliance Hymenophyllion tunbrigensis (Order Anomodonto-Polypodietalia, Class Anomodonto- Polypodietea). This alliance gathers phytocoenoses mainly made by bryophytes and pteridophytes, that inhabit sides of large rocks, walls and compact earth slopes, rootin in a thin layer of soil (exocomophytes), and developed in a really wet environment, under the canopy of forest formations. Through calculation of the «Rare specific index», coefficient of diversity phytocenotics and of botanic quality, among others, we have evaluated the zone with the aim to lay the scientific grounds for its protection and conservation

    Equilibration of Concentrated Hard Sphere Fluids

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    We report a systematic molecular dynamics study of the isochoric equilibration of hard-sphere fluids in their metastable regime close to the glass transition. The thermalization process starts with the system prepared in a non-equilibrium state with the desired final volume fraction {\phi} but with a prescribed non-equilibrium static structure factor S_0(k; {\phi}). The evolution of the {\alpha}- relaxation time {\tau}{\alpha} (k) and long-time self-diffusion coefficient DL as a function of the evolution time tw is then monitored for an array of volume fractions. For a given waiting time the plot of {\tau}{\alpha} (k; {\phi}, tw) as a function of {\phi} exhibits two regimes corresponding to samples that have fully equilibrated within this waiting time ({\phi} \leq {\phi}(c) (tw)), and to samples for which equilibration is not yet complete ({\phi} \geq {\phi}(c) (tw)). The crossover volume fraction {\phi}(c) (tw) increases with tw but seems to saturate to a value {\phi}(a) \equiv {\phi}(c) (tw \rightarrow \infty) \approx 0.582. We also find that the waiting time t^(eq)_w({\phi}) required to equilibrate a system grows faster than the corresponding equilibrium relaxation time, t^(eq)({\phi}) \approx 0.27 \times [{\tau}{\alpha} (k; {\phi})]^1.43, and that both characteristic times increase strongly as {\phi} approaches {\phi}^(a), thus suggesting that the measurement of equilibrium properties at and above {\phi}(a) is experimentally impossible

    Adam Zagajewski’s aesthetics of the sublime (Longinus)

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    En este trabajo se muestra cómo algunas de las ideas fundamentales formuladas por Longino en su tratado Sobre lo sublime están presentes en la estética de Adam Zagajewski. Se presta especial atención a tres aspectos: a) el concepto de lo sublime y la definición de la poesía, b) la estética de la recepción y c) el papel que la inspiración desempeña en la creatividad.In this paper it is shown how some of the main ideas formulated by Longinus in his treatise On the Sublime are present in the aesthetics of Adam Zagajewski. Special attention is paid to: a) the concept of the sublime and the definition of poetry, b) the aesthetics of reception, and c) the role that inspiration plays in creativity

    Influence of menstrual cycle and oral contraceptive phases on bone (re)modelling markers in response to interval running

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    To explore how sex hormone fluctuations may affect bone metabolism, this study aimed to examine P1NP and β-CTX-1 concentrations across the menstrual and oral contraceptive (OC) cycle phases in response to running. 17β-oestradiol, progesterone, P1NP and β-CTX-1 were analysed pre- and post-exercise in eight eumenorrheic females in the early-follicular, late-follicular, and mid-luteal phases, while 8 OC users were evaluated during the withdrawal and active pill-taking phases. The running protocol consisted of 8 × 3min treadmill runs at 85% of maximal aerobic speed. 17β-oestradiol concentrations (pg·ml−1) were lower in early-follicular (47.22 ± 39.75) compared to late-follicular (304.95 ± 235.85;p = < 0.001) and mid-luteal phase (165.56 ± 80.6;p = 0.003) and higher in withdrawal (46.51 ± 44.09) compared to active pill-taking phase (10.88 ± 11.24;p < 0.001). Progesterone (ng·ml−1) was higher in mid-luteal (13.214 ± 4.926) compared to early-follicular (0.521 ± 0.365; p < 0.001) and late-follicular phase (1.677 ± 2.586;p < 0.001). In eumenorrheic females, P1NP concentrations (ng·ml−1) were higher in late-follicular (69.97 ± 17.84) compared to early-follicular (60.96 ± 16.64;p = 0.006;) and mid-luteal phase (59.122 ± 11.77;p = 0.002). β-CTX-1 concentrations (ng·ml−1) were lower in mid-luteal (0.376 ± 0.098) compared to late-follicular (0.496 ± 0.166; p = 0.001) and early-follicular phase (0.452 ± 0.148; p = 0.039). OC users showed higher post-exercise P1NP concentrations in withdrawal phase (61.75 ± 8.32) compared to post-exercise in active pill-taking phase (45.45 ± 6;p < 0.001). Comparing hormonal profiles, post-exercise P1NP concentrations were higher in early-follicular (66.91 ± 16.26;p < 0.001), late-follicular (80.66 ± 16.35;p < 0.001) and mid-luteal phases (64.57 ± 9.68;p = 0.002) to active pill-taking phase. These findings underscore the importance of studying exercising females with different ovarian hormone profiles, as changes in sex hormone concentrations affect bone metabolism in response to running, showing a higher post-exercise P1NP concentrations in all menstrual cycle phases compared with active pill-taking phase of the OC cycle

    Low temperature regeneration of activated carbons using microwaves: Revising conventional wisdom

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    [EN] The purpose of this work was to explore the application of microwaves for the low temperature regeneration of activated carbons saturated with a pharmaceutical compound (promethazine). Contrary to expectations, microwave-assisted regeneration did not lead to better results than those obtained under conventional electric heating. At low temperatures the regeneration was incomplete either under microwave and conventional heating, being this attributed to the insufficient input energy. At mild temperatures, a fall in the adsorption capacity upon cycling was obtained in both devices, although this was much more pronounced for the microwave. These results contrast with previous studies on the benefits of microwaves for the regeneration of carbon materials. The fall in the adsorption capacity after regeneration was due to the thermal cracking of the adsorbed molecules inside the carbon porous network, although this effect applies to both devices. When microwaves are used, along with the thermal heating of the carbon bed, a fraction of the microwave energy seemed to be directly used in the decomposition of promethazine through the excitation of the molecular bonds by microwaves (microwave-lysis). These results point out that the nature of the adsorbate and its ability to interact with microwave are key factors that control the application of microwaves for regeneration of exhausted activated carbons.EÇ thanks The Council of Higher Education of Turkey (YÖK) for supporting her stay at INCAR (Oviedo) and the financial support of Istanbul University Research Fund (Project 3991) for her PhD thesis. JMB acknowledges CSIC for a JAE predoctoral fellowship. COA thanks the financial support of the projects CTM2008-01956 and CSIC-200980I131.Peer reviewe

    Insights in the Stock Mixing Dynamics of Atlantic Bluefin Tuna in the North Atlantic

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    Effective fisheries management requires accurate stock identification, which can be challenging in mixed stock fisheries such as the Atlantic bluefin tuna (Thunnus thynnus). This species is currently managed considering two stocks known to spawn in the Mediterranean Sea and Gulf of Mexico, respectively. However, recent studies have shown that individuals from both spawning components can interbreed at a recently discovered spawning ground, located in the Slope Sea. A better understanding of the mixing patterns, as well as the proportion in which both stocks interbreed in the Slope Sea are valuable for a reliable Atlantic bluefin tuna stock assessment. With this aim, we assigned genetic origin of 2000 individuals captured at feeding aggregates across the North Atlantic using a 96 SNP panel and analyzed the genetic profile of 500 individuals including 200 potential Slope Sea spawners (i.e., spawning capable individuals captured in this area at the spawning season), using a 8000 SNP array. We confirmed that stock mixing occurs across different feeding aggregates in the North Atlantic, being stronger in the Northwest Atlantic, where the Mediterranean component was a majority at some locations within and near the Slope Sea spawning ground. The analysis of Slope Sea spawner candidate individuals showed nearly equal representation from both Mediterranean and Gulf of Mexico genetic origin individuals, suggesting similar contribution to the Slope Sea origin offspring. Our findings constitute an important progress towards the understanding of the Atlantic bluefin tuna stock mixing dynamics and the relevance of the recently discovered Slope Sea spawning ground for the conservation of the species.En prens

    Parámetros bioquímicos a lo largo de tres microciclos de entrenamiento intenso en triatletas de élite

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    Algunos investigadores han utilizado la información que suministran determinados parámetros sanguíneos para el control biológico del entrenamiento. Entre estos parámetros los más utilizados como indicadores de sobreentrenamiento son: creatina kinasa (CK), urea (U), cortisol (C), testosterona(T) y relación testosterona/cortisol (T/C). El objetivo de este estudio fue determinar la evolución de CK, U, C,T y T/C a lo largo de 3 microciclos (M) de ntrenamiento,comparando los valores tras una sesión de entrenamientointenso con los obtenidos tras una sesión de recuperación. Seis triatletas masculinos de élite participaron en el estudio y fueron seguidos durante un periodo de entrenamiento de 31 semanas. Se estudiaron los microciclos 8, 22 y 31 (M1, M2 y M3, respectivamente). Se realizaron 7 extracciones sanguíneas en los siguientes momentos: una analítica en octubre en el periodo de descanso, y dos analíticas al final de cada M (tras una sesión de entrenamiento y una de recuperación). En cada M se registraron los datos de entrenamiento así como los de percepción de la carga y recuperación. La CK descendió de forma significativa tras una sesión de recuperación después de haber alcanzado valores significativamente superiores a los de referencia (129,5±80,2 U/l) en el M1 (Entrenamiento: 303,2±141,8 U/l vs. Recuperación: 211,3±65,4 U/l; P < 0,05), en el M2 (Entrenamiento: 316,2±134,1 U/l vs. Recuperación: 238,2±149 U/l; P < 0,05) y M3 (Entrenamiento: 383,3±231,0 U/l vs. Recuperación: 209,8±98,2 U/l; P < 0,05). Ni la U ni la T experimentaron variaciones significativas tras una sesión de recuperación, mientras que el C sólo descendió significativamente en M3 (Entrenamiento: 23±2,3 μg/dl vs. Recuperación: 18,9±2,7 μg/dl: P < 0,05). En conclusión, este estudio muestra las variaciones que experimentan varios parámetros sanguíneos a lo largo de tres microciclos de entrenamiento intenso, en los que ninguno de los deportistas experimentó ningún síntoma de sobreentrenamiento
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