3,972 research outputs found

    Una aproximación estadística al estudio de la carbonatación del hormigón

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    Carbonation is one of the factors that conditions reinforced concrete durability, while porosity is one of the parameters that determines the carbonation rate: as a rule, the greater the porosity, the higher the rate. While many papers have been published on the effect of CO2 penetration in the pore solutions of concretes prepared under different experimental conditions, the literature has yet to address the joint effect of the factors considered in concrete design, such as the water/cement (w/c) ratio, type of cement, type of aggregate and presence of admixtures. The present paper discusses the findings of a statistical study of the impact of the aforementioned factors on both system porosity and carbonation rate. The type of cement, individually and in its interaction with the rest of the factors, proved to be the major determinant in concrete carbonation.La carbonatación es uno de los factores que supedita la durabilidad del hormigón armado, siendo la porosidad uno de los parámetros que más condicionan la velocidad de carbonatación. Son muchos los trabajos que estudian el efecto de la penetración del CO2 en la solución de los poros de hormigones preparados bajo distintas condiciones experimentales, sin embargo, no se encuentran referencias que analicen de forma conjunta el efecto de ciertos factores como son la relación agua/cemento (a/c ratio), el tipo de cemento, el tipo de árido y la presencia de aditivos, normalmente consideradas a la hora de diseñar un hormigón. En este trabajo se discuten los resultados obtenidos tras realizar un estudio estadístico del efecto que tienen los factores previamente mencionados, tanto en la porosidad de estos sistemas como en su nivel de carbonatación. El cemento tanto de manera individual como en sus interacciones con el resto de los factores es el factor que mas afecta a la carbonatación del hormigón

    Computer model validation with functional output

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    A key question in evaluation of computer models is Does the computer model adequately represent reality? A six-step process for computer model validation is set out in Bayarri et al. [Technometrics 49 (2007) 138--154] (and briefly summarized below), based on comparison of computer model runs with field data of the process being modeled. The methodology is particularly suited to treating the major issues associated with the validation process: quantifying multiple sources of error and uncertainty in computer models; combining multiple sources of information; and being able to adapt to different, but related scenarios. Two complications that frequently arise in practice are the need to deal with highly irregular functional data and the need to acknowledge and incorporate uncertainty in the inputs. We develop methodology to deal with both complications. A key part of the approach utilizes a wavelet representation of the functional data, applies a hierarchical version of the scalar validation methodology to the wavelet coefficients, and transforms back, to ultimately compare computer model output with field output. The generality of the methodology is only limited by the capability of a combination of computational tools and the appropriateness of decompositions of the sort (wavelets) employed here. The methods and analyses we present are illustrated with a test bed dynamic stress analysis for a particular engineering system.Comment: Published in at http://dx.doi.org/10.1214/009053607000000163 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    El futuro de las revistas científicas españolas: un esfuerzo científico, social e institucional

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    In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates.In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates.In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates

    Post-2020 biodiversity targets need to embrace climate change

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    Recent assessment reports by the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) have highlighted the risks to humanity arising from the unsustainable use of natural resources. Thus far, land, freshwater, and ocean exploitation have been the chief causes of biodiversity loss. Climate change is projected to be a rapidly increasing additional driver for biodiversity loss. Since climate change and biodiversity loss impact human societies everywhere, bold solutions are required that integrate environmental and societal objectives. As yet, most existing international biodiversity targets have overlooked climate change impacts. At the same time, climate change mitigation measures themselves may harm biodiversity directly. The Convention on Biological Diversity's post-2020 framework offers the important opportunity to address the interactions between climate change and biodiversity and revise biodiversity targets accordingly by better aligning these with the United Nations Framework Convention on Climate Change Paris Agreement and the Sustainable Development Goals. We identify the considerable number of existing and proposed post- 2020 biodiversity targets that risk being severely compromised due to climate change, even if other barriers to their achievement were removed. Our analysis suggests that the next set of biodiversity targets explicitly addresses climate change-related risks since many aspirational goals will not be feasible under even lower-end projections of future warming. Adopting more flexible and dynamic approaches to conservation, rather than static goals, would allow us to respond flexibly to changes in habitats, genetic resources, species composition, and ecosystem functioning and leverage biodiversity's capacity to contribute to climate change mitigation and adaptation

    Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

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    This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.Copyright © 2022 Moreno-Castaño, Salas, Palomo, Martinez-Sanchez, Rovira, Fernández-Avilés, Martínez, Cid, Castro, Escolar, Carreras and Diaz-Ricart

    Cosmological solutions from fake N=2 EYM supergravity

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    We characterise the (fake) supersymmetric solutions of Wick-rotated N=2 d=4 gauged supergravity coupled to non-Abelian vector multiplets. In the time-like case we obtain generalisations of Kastor & Traschen's cosmological black holes: they have a specific time-dependence and the base-space must be 3-dimensional hyperCR/Gauduchon-Tod space. In the null-case, we find that the metric has a holonomy contained in Sim(2), give a general characterisation of the solutions, and give some examples. Finally, we point out that in some cases the solutions we found are non-BPS solutions to N=2 d=4 supergravity coupled to vector multiplets.Comment: 30 pages. Comments and references added, typos correcte

    A mixed-methods feasibility study of a goal-focused manualised intervention to support people with dementia to stay living independently at home with support from family carers: NIDUS (New Interventions for Independence in Dementia Study) Family

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    Objectives: To examine the feasibility and acceptability of NIDUS-Family, a 6–8 session manualised, individually tailored, modular intervention supporting independence at home for people with dementia; and explore participants’ and facilitators’ experiences of the intervention. / Method: In this single group multi-site feasibility study, trained, supervised non-clinically qualified graduates (facilitators) delivered NIDUS-Family to family carer and people living with dementia dyads. We recruited participants from GP practices and memory services in London and Bradford. We completed quantitative outcomes pre- and post-intervention; and conducted qualitative interviews with participants and facilitators. Our pre-specified main outcomes were proportion of potential participants approached who agreed to participate, intervention adherence and acceptability to family carers, and facilitator fidelity to the manual. / Results: We recruited 16 dyads (57% of those approached); 12 (75%) completed the intervention. Of 12 participants rating intervention acceptability, 9 (75%) agreed or strongly agreed that it had helped; 2 (18%) neither agreed nor disagreed and 1 (8%) disagreed. Mean facilitator fidelity was high (81.5%). Dyads set on average 3.9 goals; these most commonly related to getting out and about and increasing activity/hobby participation (n = 10); carer wellbeing (n = 6), managing physical complaints (n = 6); meal preparation/cooking (n = 5); and reducing irritability, frustration or aggression (n = 5). Almost all secondary outcomes changed in a direction indicating improvement. In our qualitative analysis we identified three overarching themes; relationships facilitate change, goal-focused versus manualised approach and balancing the needs of carers and people with dementia. / Conclusion: NIDUS-Family was feasible and acceptable to participants. Following refinements, testing in a pragmatic trial is underway

    Establishing a Reference Baseline for Midday Stem Water Potential in Olive and Its Use for Plant-Based Irrigation Management

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    Midday stem water potential (SWP) is rapidly becoming adopted as a standard tool for plant-based irrigation management in many woody perennial crops. A reference or “baseline” SWP has been used in some crops (almond, prune, grape, and walnut) to account for the climatic influence of air vapor pressure deficit (VPD) on SWP under non-limiting soil moisture conditions. The baseline can be determined empirically for field trees maintained under such non-limiting conditions, but such conditions are difficult to achieve for an entire season. We present the results of an alternative survey-based approach, using a large set of SWP and VPD data collected over multiple years, from irrigation experiments in olive orchards located in multiple countries [Spain, United States (California), Italy, and Argentina]. The relation of SWP to midday VPD across the entire data set was consistent with an upper limit SWP which declined with VPD, with the upper limit being similar to that found in Prunus. A best fit linear regression estimate for this upper limit (baseline) was found by selecting the maximum R2 and minimum probability for various upper fractions of the SWP/VPD relation. In addition to being surprisingly similar to the Prunus baseline, the olive baseline was also similar (within 0.1 MPa) to a recently published mechanistic olive soil-plant-atmosphere-continuum (SPAC) model for “super high density” orchard systems. Despite similarities in the baseline, the overall physiological range of SWP exhibited by olive extends to about −8 MPa, compared to about −4 MPa for economically producing almond. This may indicate that, despite species differences in physiological responses to low water availability (drought), there may be convergent adaptations/acclimations across species to high levels of water availability. Similar to its use in other crops, the olive baseline will enable more accurate and reproducible plant-based irrigation management for both full and deficit irrigation practices, and we present tentative SWP guidelines for this purpose

    Measurement of 73 Ge(n,γ) cross sections and implications for stellar nucleosynthesis

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    © 2019 The Author(s). Published by Elsevier B.V.73 Ge(n,γ) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT=30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of 73 Ge produced in stars, which would explain the low isotopic abundance of 73 Ge in the solar system.Peer reviewe
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