El medio ambiente y el golf en Cataluña : problemas y perspectivas

Cet article expose les résultats d'une recherche sur l'environnement et le golf en Catalogne. On a tout d'abord étudié les changements dans l'utilisation du sol avant et après la construction des terrains de golf. Ensuite on a dressé une typologie des changements survenus afin d'établir une évaluation du paysage. Dans la deuxième partie on a étudié les différents paramètres d'ordre climatique des endroits ou se localisent les terrains de golf on a annalysé les bilans hydriques et d'évapotranspiration. Les données obtenues et les valeurs concemant la consommation d'eau ont pennis d'estimer l'incidence sur l'environnement physique et social des terrains étudiés. L'eau étant le facteur primordial pour l'existence des terrains de golf dans les régions méditerranéennes, il a fallu analyser soigneusement les valeurs de consommation d'eau ainsi que ses différents sources d'approvisionnement. Finalement on afait des recommandations aux terrains existants et à ceux qui sont en project pour une réutilisation continue des eaux, pour éviter l'introduction des lacs artificiels et pour une mise en valeur de tous les éléments du paysage méditerranéen afin de préserver l'environnement dans la mesure du possible.This article summarises the environmental aspects of the results of a research project on golf in Catalonia. The first part studies the changes in land use, based on the comparison between present use and that prior to the construction of each course. This is followed by the establishment of a typology of these changes, with the objective of offering an evaluation of landscape. In the second part, the climatic characteristics of the diferents zones in which the courses are located, are analysed, together with the hydric balance and evapotranspiration levels. On the basis of these statistics and those refering to water consumption, it has been possible to estimate the environmental impact of the courses. Evidently, given that the availability of water is the principal determining factor which enables their existence in Mediterranean regions, aspects not only of consumption, but also of sources of supply, have been carefully examined. Finally some basic recommendations are offered, to facilitate the maintenance of existing courses and construction of news ones within environmentally acceptable parameters. These include the use of treated waste water for irrigation, the avoidance of artificial lakes in course design, and the maximum use of Mediterranean landscape elements, with the objective of conserving, as far as possible the natural environment.L'article presenta els resultats de la investigació sobre el medi ambient i el golf a Catalunya. S'inicia amb l'estudi dels canvis d'usos del sol, a partir de la comparació de l'ús anterior i posterior a la construcció dels camps. Després es passa a l'establiment de la tipologia dels canvis, a fi d'establir una valoració paisatgística. En un segon apartat, s'estudien els diversos paràmetres climàtics de les diverses àrees on es localitzen els camps, i es fa una anàlisi dels balanços hídrics i evapotranspiració. Amb les dades d'aquests paràmetres i els valors dels consums d'aigua s'ha pogut estimar la incidència sobre el medi ambiental i social dels camps estudiats. Com que l'aigua és el factor principal per a l'existència de camps de golf en zones mediterrànies, ha calgut analitzar-la acuradament, tant en els consums com en les diferents fonts d'aprovisionament. Finalment, hem suggerit unes ecomanacions bàsiques per poder continuar mantenint els camps ja existents i els nous mitjançant la reutilització continuada de les aigües, la no introducció de dissenys amb llacs artificials i l'aprofitament de tots els elements del paisatge mediterrani, a fi de preservar tant com es pugui l'entorn natural.El articulo presenta los resultados de la investigación acerca del medio ambiente y el golf en Cataluña. Se inicia con el estudio de los cambios de usos del suelo a partir de la comparación del uso anterior y posterior a la construcción de dichos campos. Luego se procede a la tipologia de los cambios a fin de ofrecer una valoración paisajistica. En un segundo apartado se estudian los distintos parámetros climáticos de las diversas áreas donde se ubican los campos, y se efectúa un análisis de los balances hídricos y de evapotranspiración. Con los datos de dichos parámetros y 10s valores de los consumos de agua, se ha pormenorizado acerca de la incidencia sobre el medio ambiental y social de dichos campos. El agua, al ser el factor principal para la existencia de campos de golf en sectores mediterráneos, ha sido cuidadosamente analizada, tanto en los consumos como las distintas fuentes de abastecimiento. Finalmente, hemos sugerido unas recomendaciones básicas para poder continuar manteniendo los campos ya existentes y los nuevos mediante la reutilización continuada de las aguas, a base de no introducir diseños con lagos artificiales y de aprovechar todos los elementos del paisaje mediterráneo, a fin de preservar en lo posible el medio natural

The efficiency of grain growth in the diffuse interstellar medium

Grain growth by accretion of gas-phase metals is a common assumption in models of dust evolution, but in dense gas, where the timescale is short enough for accretion to be effective, material is accreted in the form of ice mantles rather than adding to the refractory grain mass. It has been suggested that negatively-charged small grains in the diffuse interstellar medium (ISM) can accrete efficiently due to the Coulomb attraction of positively-charged ions, avoiding this issue. We show that this inevitably results in the growth of the small-grain radii until they become positively charged, at which point further growth is effectively halted. The resulting gas-phase depletions under diffuse ISM conditions are significantly overestimated when a constant grain size distribution is assumed. While observed depletions can be reproduced by changing the initial size distribution or assuming highly efficient grain shattering, both options result in unrealistic levels of far-ultraviolet extinction. We suggest that the observed elemental depletions in the diffuse ISM are better explained by higher initial depletions, combined with inefficient dust destruction by supernovae at moderate (nH ∼ 30 cm−3) densities, rather than by higher accretion efficiences

The impact of metallicity-dependent dust destruction on the dust-to-metals ratio in galaxies

The ratio of the mass of interstellar dust to the total mass of metals (the dust-to-metals/DTM ratio) tends to increase with metallicity. This can be explained by the increasing efficiency of grain growth in the interstellar medium (ISM) at higher metallicities, with a corollary being that the low DTM ratios seen at low metallicities are due to inefficient stellar dust production. This interpretation assumes that the efficiency of dust destruction in the ISM is constant, whereas it might be expected to increase at low metallicity; the decreased cooling efficiency of low-metallicity gas should result in more post-shock dust destruction via thermal sputtering. We show that incorporating a sufficiently strong metallicity dependence into models of galaxy evolution removes the need for low stellar dust yields. The contribution of stellar sources to the overall dust budget may be significantly underestimated, and that of grain growth overestimated, by models assuming a constant destruction efficiency

The mass, location and heating of the dust in the Cassiopeia A supernova remnant

We model the thermal dust emission from dust grains heated by synchrotron radiation and by particle collisions, under conditions appropriate for four different shocked and unshocked gas components of the Cassiopeia A (Cas A) supernova remnant (SNR). By fitting the resulting spectral energy distributions (SEDs) to the observed SNR dust fluxes, we determine the required mass of dust in each component. We find the observed SED can be reproduced by $\sim 0.6 \, {\rm M_\odot}$ of silicate grains, the majority of which is in the unshocked ejecta and heated by the synchrotron radiation field. Warmer dust, located in the X-ray emitting reverse shock and blastwave regions, contribute to the shorter wavelength infrared emission but make only a small fraction of the total dust mass. Carbon grains can at most make up $\sim 25 \%$ of the total dust mass. Combined with estimates for the gas masses, we obtain dust-to-gas mass ratios for each component, which suggest that the condensation efficiency in the ejecta is high, and that dust in the shocked ejecta clumps is well protected from destruction by sputtering in the reverse shock.Comment: Accepted by MNRAS, 14 pages, 6 figures. Author accepted manuscript. Accepted on 05/02/2019. Deposited on 05/02/201

Dust masses and grain size distributions of a sample of Galactic pulsar wind nebulae

We calculate dust spectral energy distributions (SEDs) for a range of grain sizes and compositions, using physical properties appropriate for five pulsar wind nebulae (PWNe) from which dust emission associated with the ejecta has been detected. By fitting the observed dust SED with our models, with the number of grains of different sizes as the free parameters, we are able to determine the grain size distribution and total dust mass in each PWN. We find that all five PWNe require large (⁠≥0.1μm⁠) grains to make up the majority of the dust mass, with strong evidence for the presence of micron-sized or larger grains. Only two PWNe contain non-negligible quantities of small (⁠<0.01μm⁠) grains. The size distributions are generally well-represented by broken power laws, although our uncertainties are too large to rule out alternative shapes. We find a total dust mass of 0.02−0.28M⊙ for the Crab Nebula, depending on the composition and distance from the synchrotron source, in agreement with recent estimates. For three objects in our sample, the PWN synchrotron luminosity is insufficient to power the observed dust emission, and additional collisional heating is required, either from warm, dense gas as found in the Crab Nebula, or higher temperature shocked material. For G54.1+0.3, the dust is heated by nearby OB stars rather than the PWN. Inferred dust masses vary significantly depending on the details of the assumed heating mechanism, but in all cases large mass fractions of micron-sized grains are required

Constraining early-time dust formation in core-collapse supernovae

There is currently a severe discrepancy between theoretical models of dust formation in core-collapse supernovae (CCSNe), which predict $\gtrsim 0.01$ M$_\odot$ of ejecta dust forming within $\sim 1000$ days, and observations at these epochs, which infer much lower masses. We demonstrate that, in the optically thin case, these low dust masses are robust despite significant observational and model uncertainties. For a sample of 11 well-observed CCSNe, no plausible model reaches carbon dust masses above $10^{-4}$ M$_\odot$, or silicate masses above $\sim 10^{-3}$ M$_\odot$. Optically thick models can accommodate larger dust masses, but the dust must be clumped and have a low ($<0.1$) covering fraction to avoid conflict with data at optical wavelengths. These values are insufficient to reproduce the observed infrared fluxes, and the required covering fraction varies not only between SNe but between epochs for the same object. The difficulty in reconciling large dust masses with early-time observations of CCSNe, combined with well-established detections of comparably large dust masses in supernova remnants, suggests that a mechanism for late-time dust formation is necessary.Comment: 14 pages, 13 figures. MNRAS accepted 10/07/2

Revisiting the dust destruction efficiency of supernovae

Dust destruction by supernovae is one of the main processes removing dust from the interstellar medium (ISM). Estimates of the efficiency of this process, both theoretical and observational, typically assume a shock propagating into a homogeneous medium, whereas the ISM possesses significant substructure in reality. We self-consistently model the dust and gas properties of the shocked ISM in three supernova remnants (SNRs), using X-ray and infrared (IR) data combined with corresponding emission models. Collisional heating by gas with properties derived from X-ray observations produces dust temperatures too high to fit the far-IR fluxes from each SNR. An additional colder dust component is required, which has a minimum mass several orders of magnitude larger than that of the warm dust heated by the X-ray emitting gas. Dust-to-gas mass ratios indicate that the majority of the dust in the X-ray emitting material has been destroyed, while the fraction of surviving dust in the cold component is plausibly close to unity. As the cold component makes up virtually all the total dust mass, destruction timescales based on homogeneous models, which cannot account for multiple phases of shocked gas and dust, may be significantly overestimating actual dust destruction efficiencies, and subsequently underestimating grain lifetimes

The role of serial European windstorm clustering for extreme seasonal losses as determined from multi-centennial simulations of high resolution global climate model data

Extratropical cyclones are the most damaging natural hazard to affect western Europe. Serial clustering occurs when many intense cyclones affect one specific geographic region in a short period of time which can potentially lead to very large seasonal losses. Previous studies have shown that intense cyclones may be more likely to cluster than less intense cyclones. We revisit this topic using a high resolution climate model with the aim to determine how important clustering is for windstorm related losses. The role of windstorm clustering is investigated using a quantifiable metric (storm severity index, SSI) that is based on near surface meteorological variables (10-metre wind speed) and is a good proxy for losses. The SSI is used to convert a wind footprint into losses for individual windstorms or seasons. 918 years of a present-day ensemble of coupled climate model simulations from the High-Resolution Global Environment Model (HiGEM) are compared to ERA-Interim re-analysis. HiGEM is able to successfully reproduce the wintertime North Atlantic/European circulation, and represent the large-scale circulation associated with the serial clustering of European windstorms. We use two measures to identify any changes in the contribution of clustering to the seasonal windstorm loss as a function of return period. Above a return period of 3 years, the accumulated seasonal loss from HiGEM is up to 20% larger than the accumulated seasonal loss from a set of random resamples of the HiGEM data. Seasonal losses are increased by 10-20% relative to randomised seasonal losses at a return period of 200 years. The contribution of the single largest event in a season to the accumulated seasonal loss does not change with return period, generally ranging between 25-50%. Given the realistic dynamical representation of cyclone clustering in HiGEM, and comparable statistics to ERA-Interim, we conclude that our estimation of clustering and its dependence on the return period will be useful for informing the development of risk models for European windstorms, particularly for longer return periods

School-based curriculum development in Scotland: Curriculum policy and enactment

Recent worldwide trends in curriculum policy have re-emphasised the role of teachers in school-based curriculum development. Scotland&rsquo;s Curriculum for Excellence is typical of these trends, stressing that teachers are agents of change. This paper draws upon empirical data to explore school-based curriculum development in response to Curriculum for Excellence. We focus on two case studies &ndash; secondary schools within a single Scottish local education authority. In the paper we argue that the nature and extent of innovation in schools is dependent upon teachers being able to make sense of often complex and confusing curriculum policy, including the articulation of a clear vision about what such policy means for education within each school

Case study:shipping trend estimation and prediction via multiscale variance stabilisation

<p>Shipping and shipping services are a key industry of great importance to the economy of Cyprus and the wider European Union. Assessment, management and future steering of the industry, and its associated economy, is carried out by a range of organisations and is of direct interest to a number of stakeholders. This article presents an analysis of shipping credit flow data: an important and archetypal series whose analysis is hampered by rapid changes of variance. Our analysis uses the recently developed data-driven Haar–Fisz transformation that enables accurate trend estimation and successful prediction in these kinds of situation. Our trend estimation is augmented by bootstrap confidence bands, new in this context. The good performance of the data-driven Haar–Fisz transform contrasts with the poor performance exhibited by popular and established variance stabilisation alternatives: the Box–Cox, logarithm and square root transformations.</p