120 research outputs found
Conserved charges in timelike warped AdS3 spaces
We consider the timelike version of warped anti-de Sitter space (WAdS), which corresponds to the three-dimensional section of the Gödel solution of four-dimensional cosmological Einstein equations. This geometry presents closed timelike curves (CTCs), which are inherited from its four-dimensional embedding. In three dimensions, this type of solution can be supported without matter provided the graviton acquires mass. Here, among the different ways to consistently give mass to the graviton in three dimensions, we consider the parity-even model known as new massive gravity (NMG). In the bulk of timelike WAdS3 space, we introduce defects that, from the three-dimensional point of view, represent spinning massive particlelike objects. For this type of source, we investigate the definition of quasilocal gravitational energy as seen from infinity, far beyond the region where the CTCs appear. We also consider the covariant formalism applied to NMG to compute the mass and the angular momentum of spinning particlelike defects and compare the result with the one obtained by means of the quasilocal stress tensor. We apply these methods to special limits in which the WAdS3 solutions coincide with locally AdS3 and locally AdS2×R spaces. Finally, we make some comments about the asymptotic symmetry algebra of asymptotically WAdS3 spaces in NMG.Fil: Donnay, L.. Université Libre de Bruxelles; BélgicaFil: Fernández Melgarejo, J.J.. Harvard University; Estados UnidosFil: Giribet, Gaston Enrique. Université Libre de Bruxelles; Bélgica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Pontificia Universidad Católica de Valparaíso; ChileFil: Goya, Andrés Fabio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Lavia, Edmundo. Ministerio de Defensa. Armada Argentina. Dirección Gral. de Investigación y Desarrollo de la Ara. Dirección de Investigación de la Armada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Towards an agile participatory urban soundscape planning framework
This paper presents an agile participatory urban soundscape planning process model, which is proposed as a prerequisite on which to build and reference the efficacy of urban soundscape planning. The model was developed through data synthesis and analysis and mapping engagement with diverse stakeholders across four applied soundscape projects in Brighton and Hove, UK. To the best of the authors’ knowledge, the model is the first of its kind in applied soundscape practice. The data was collected through semi-structured interviews with key stakeholders and document analysis of published resources. The framework used for the analysis of the findings comprised four core urban planning stages: goals and objectives, engagement (e.g. prediction/modelling/design/planning), implications, evaluation. The study found that when integrating soundscape planning with core urban planning stages it was necessary to first identify the appropriate stakeholders in relation to the project context. It was found that these stakeholders could be wide-ranging and unexpected, thereby reinforcing the appropriateness of incorporating an agile approach in the resulting model. The study also found that users’ perceptions are central to soundscape practice and need to be considered at each stage of a planning process to produce an effective and sustainable outcome. A variety of specific events, appropriate to the requirements of the stakeholders, are important for engaging planning authorities, users and other stakeholders at different stages. This study also demonstrated that an evidence-based evaluation method is recommended in an agile participatory urban soundscape planning process to assess stakeholders’ engagement at each stage and to inform and guide subsequent steps in the planning process relevant to the local context(s)
Ein Neues Verfahren zur Messung der Bakteriziden Fähigkeit des Vollblutes
Das oben erwahnte Verfahren hat vor den anderen Methoden
besonders die Vorzuge, 1) daβ man dadurch zu einem sicheren Resultat gelangen und gleichzeitig auch jedes Datum mit exakten Ziffern zum Ausdruck bringen kann, 2) daβ bei diesem Verfahren keineswegs erforderlich ist, eine bestimmte Anzahl von Keimen einschlieβende Bakterienaufschwemmung herzusteHen und auch Kontrollversuch anzustellen, 3) daβ es von den Fehlern des Mischverhaltnisses zwischen der Bakterienlosung und dem Blut nicht so erheblich beeinfluβt wird, und 4) daβ man durch dieses Verfahren gleichzeitig mehrere bakterientotende Faktoren untersuchen kann. Ferner hat dieses Verfahren auch den Vorzug, daβ es praktisch sehr einfach auszufuhren ist und nur 6 Stunden nach der Blutentnahme bereits das Ergebnis liefert. Es gestattet ferner, die bakterizide Kraft des Blutes gleichzeitig bei 6 - 8 Menschen zu untersuchen, was mich zur Uberzeugung fuhrt, daβ es in der Klinik hochgeschatzt werden wird. Auch das Verfahren und die ebenfalls vom mir aufgestellte Formel zur zusammenfassenden Beurteilung kann man nach meinem Erachten durch entsprechende Veranderungen einiger Faktoren ohne jede Schwierigkeiten auch fur andere Bakterienarten anwenden. Man wird wohl gegen eine einzige Lucke dieses Verfahrens, daβ die mikroskopische Untersuchung und die Berechnung allzu verwickelt zu sein scheint, Einwand erheben, eine Lucke, zu deren Schluβ jedoch nur eine kurzfristige Ubung erfordert wird, durch
welche die mikroskopische Untersuchung innerhalb 30 Minuten, die Berechnung nur in 5 Minuten vollendet werden kann. (Zur Berechnung bedarf es einer Gauss'schen Logarithmentafel.) Obgleich das geschilderte Verfahren noch viele, genauere Prufungen erheischende Punkte in sich einschlieβt, muβ es hier, wenn auch in Grundzugen, jetzt schon angefuhrt werden,. da ich der festen Uberzeugung bin, daβ es im Vergleich zu den bisherigen Methoden ein dem wirklichen Wert der Bakterizidie des Vollblutes im lebenden Organismus viel naheres Resultat liefert.</p
Modeling the evolution of item rating networks using time-domain preferential attachment
The understanding of the structure and dynamics of the intricate network of connections among people that consumes products through Internet appears as an extremely useful asset in order to study emergent properties related to social behavior. This knowledge could be useful, for example, to improve the performance of personal recommendation algorithms. In this contribution, we analyzed five-year records of movie-rating transactions provided by Netflix, a movie rental platform where users rate movies from an online catalog. This dataset can be studied as a bipartite user-item network whose structure evolves in time. Even though several topological properties from subsets of this bipartite network have been reported with a model that combines random and preferential attachment mechanisms [Beguerisse Díaz et al., 2010], there are still many aspects worth to be explored, as they are connected to relevant phenomena underlying the evolution of the network. In this work, we test the hypothesis that bursty human behavior is essential in order to describe how a bipartite user-item network evolves in time. To that end, we propose a novel model that combines, for user nodes, a network growth prescription based on a preferential attachment mechanism acting not only in the topological domain (i.e. based on node degrees) but also in time domain. In the case of items, the model mixes degree preferential attachment and random selection. With these ingredients, the model is not only able to reproduce the asymptotic degree distribution, but also shows an excellent agreement with the Netflix data in several time-dependent topological properties
Assessing community noise annoyance: a review of two decades of the international technical specification ISO/TS 15666:2003
The robust assessment of noise annoyance is of key importance given that it is the most prevalent community response in populations exposed to environmental noise. In 1993 the International Commission on Biological Effects of Noise Community Response to Noise team began formalizing a standardized methodology for assessing noise annoyance, which resulted in reporting guidelines and recommendations later published as a Technical Specification (TS) by the International Standards Organization in 2003 (ISO/TS 15666: 2003). This TS, intended to inform the international community on the quantification of the exposure-response relationship between noise exposure and annoyance, has been in circulation for nearly two decades and has been updated in 2021 (ISO/TS 15666: 2021) by an international working group (ISO TC43/SC1/WG62). This paper reviews use of the 2003 TS, identifies common adaptations in use and summarizes the revisions. Methodological issues arising from the use of the 5-point verbal and the 11-point numeric scale questions and the scoring of ‘highly annoyed’ are discussed. The revisions are designed to encourage further standardization in noise annoyance research. The paper highlights research needs that if addressed would strengthen the methodology underlying the assessment of noise annoyance including multidimensional assessments of annoyance
Ten questions on the soundscapes of the built environment
Soundscape research represents a paradigm shift from noise control policies towards a new multidisciplinary approach as it involves not only physical measurements but also the cooperation of humanity and social sciences to account for the diversity of soundscapes across countries and cultures, with more focus on how people actually experience the acoustic environments; and it considers environmental sounds as a ‘resource’ rather than a ‘waste’. The ten questions presented in this paper range from the very basic definitions underlying the emerging soundscape ‘science’, to more applied topics about how to use soundscape as a design approach for the planning and management of the built environments. Although significant research activity has been conducted so far, there is still a need to systematically provide the underpinning science and practical guidance in soundscaping. Thus, the last question aims to identify the most crucial gaps in soundscape research and set the agenda for future advancements in the field
Development and testing of Indoor Soundscape Questionnaire for evaluating contextual experience in public spaces
An Indoor Soundscape Questionnaire aiming at the evaluation of indoor public sound environments was designed, statistically tested and presented. It was established through initial pilot studies and three main factors under contextual experience variable are established as (1) psychological factors, (2) space usage factors and (3) demographical factors. In addition to the questions on demographical and space usage factors, detailed questions on psychological factors are designed and statistically tested for expectation, perception and reaction categories of the psychological factor. The questionnaire was applied as part of a case study in enclosed library foyer environments to a group of 270 participants through non-experimental survey data sampling. The reliability and validity scores of the Indoor Soundscape Questionnaire were statistically tested and confirmed. Furthermore, statistical tests were used to derive relationships between contextual experience variables of psychological, space usage and demographical factors. Chi-square test of goodness-of-fit results showed statistical significances of demographical and space usage factors with the psychological factors
Design of urban furniture to enhance the soundscape: A case study
In modern urban scenarios all the aspects of the historical heritage, including public open spaces and ancient buildings, have to meet the high increase of density of infrastructures and constructions, with the consequent change of visual and sound environments. This in turn affects people’s quality of life. Because of the growing interest on this problem, this study investigates the relationship between soundscape and design solutions for urban furniture, considering technical and environmental feasibility of the designing process, from the materials characteristics, to the acoustic and psychoacoustic impact of the tool on the user. The process includes the acoustic suitability of 3D printing materials, the suitability of acoustic design using software simulation, the experimental assessment of the performance of the 3D printed prototype, and the statistical evaluation of the chosen studying parameters and conditions. This paper describes all the stages of the designing process, with a focus on the study of shapes and volumes of the prototype and on its impact on the user’s perception. FEM simulations and experimental tests performed in a semi-anechoic chamber allowed to validate the design process. These analyses proved that the designed prototype of urban furniture can not only positively influence the physical environment but also the psychoacoustic perception of it
CARACTERIZAÇÃO MORFOLÓGICA DE ACESSOS DE GERMOPLASMA DE QUATRO ESPÉCIES BRASILEIRAS DE AMENDOIM-SILVESTRE
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The science of soundscape - summary of the evidence base from the UK acoustics community
The Science of Soundscape – Summary of the Evidence Base from the UK Acoustics Community provides a comprehensive summary of the scientific evidence supporting the use of a soundscape approach in environmental design and planning. The lead author was Peter Rogers; we contributed to the text with a case study, Soundscape approach for a residential development. The paper was written in response to a request from the UK House of Lords for information on the evidence base around soundscapes and their benefits for wellbeing. It provides background on the concept of soundscapes as distinct from just noise levels. Soundscapes consider the perception of sound in context. The paper summarizes evidence from many studies showing health and wellbeing benefits of natural sounds and positive soundscapes. Case studies demonstrate practical applications of soundscape principles in urban design projects. The paper calls for greater inclusion of soundscapes in policy frameworks, citing initial steps taken in Wales. It brings together views of many UK acoustics experts to give a broad scientific summary of the current state of knowledge on soundscapes. The paper makes the case for the science supporting soundscapes as a complement to traditional noise management, with benefits for human health and sustainability. It provides evidence requested by policymakers considering this approach
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