644 research outputs found

    Supersymmetric black holes in 2D dilaton supergravity: baldness and extremality

    Full text link
    We present a systematic discussion of supersymmetric solutions of 2D dilaton supergravity. In particular those solutions which retain at least half of the supersymmetries are ground states with respect to the bosonic Casimir function (essentially the ADM mass). Nevertheless, by tuning the prepotential appropriately, black hole solutions may emerge with an arbitrary number of Killing horizons. The absence of dilatino and gravitino hair is proven. Moreover, the impossibility of supersymmetric dS ground states and of nonextremal black holes is confirmed, even in the presence of a dilaton. In these derivations the knowledge of the general analytic solution of 2D dilaton supergravity plays an important role. The latter result is addressed in the more general context of gPSMs which have no supergravity interpretation. Finally it is demonstrated that the inclusion of non-minimally coupled matter, a step which is already nontrivial by itself, does not change these features in an essential way.Comment: 30 pages, LaTeX, v2: mayor revision (rearranged title, shortened abstract, revised introduction, inserted section from appendix to main text, added subsection with new material on non-SUGRA gPSMs, added clarifying remarks at some places, updated references); v3: corrected minor misprints, added note with a new referenc

    Chemical-physical and ecological characterisation in the environmental project of a polluted coastal area: the Bagnoli case study

    Get PDF
    The Bagnoli Bay (southern Tyrrhenian Sea, Naples, Italy) has been impacted for about one century by heavy anthropogenic pollution due to an important steel plant. A multidisciplinary environmental research, aimed at the reclamation of the marine contaminated area, was planned in order to evaluate, through quantitative data, the chemical-physical and ecological characteristics of marine sediments; the latter ones are strictly related to the composition and structure of benthic foraminiferal assemblages. A comprehensive statistical approach, considering all data, was attempted in order to single out the influence of pollutants on the single species distribution. The results show strong heavy metal pollution (Fe, Mn, Pb and Zn) in the vicinity of the industrial plant. Many foraminiferal species (Haynesina germanica, Miliolinella subrotunda,Quinqueloculina parvula), have a good tolerance to some trace metals while, Bulimina sublimbata, Elphidiummacellum and Miliolinella dilatata show a good tolerance to PAHs pollution

    A machine learning resource allocation solution to improve video quality in remote education

    Get PDF
    The current global pandemic crisis has unquestionably disrupted the higher education sector, forcing educational institutions to rapidly embrace technology-enhanced learning. However, the COVID-19 containment measures that forced people to work or stay at home, have determined a significant increase in the Internet traffic that puts tremendous pressure on the underlying network infrastructure. This affects negatively content delivery and consequently user perceived quality, especially for video-based services. Focusing on this problem, this paper proposes a machine learning-based resource allocation solution that improves the quality of video services for increased number of viewers. The solution is deployed and tested in an educational context, demonstrating its benefit in terms of major quality of service parameters for various video content, in comparison with existing state of the art. Moreover, a discussion on how the technology is helping to mitigate the effects of massively increasing internet traffic on the video quality in an educational context is also presented

    Composição proximal em filés, rendimento de carcaça e de cortes de jundiá (rhamdia quelen) alimentados com rações contendo diferentes óleos vegetais.

    Get PDF
    Este trabalho teve por objetivos avaliar a influência de óleos vegetais no desenvolvimento corporal de jundiá (Rhamdia quelen, Heptapteridae) e sua relação com o rendimento de carcaça, partes comestíveis e composição química do filé. Testaram-se seis rações com 32% de proteína bruta, sendo avaliados óleos de arroz, canola ou soja com 5 e 10% de inclusão durante 90 dias. Foram utilizados 180 peixes (peso inicial=71±0,81g) distribuídos ao acaso em 18 caixas de 280L (10 peixes/caixa) em um sistema de recirculação de água, com temperatura controlada (25,9±0,9ºC). Não houve diferenças para os parâmetros produtivos entre os tratamentos testados ao final do experimento (P<0,05). Os peixes alimentados com maiores níveis de óleo nas dietas depositaram maior porcentagem de gordura no filé. Conclui-se que os óleos de canola, arroz e soja utilizados como alternativas em dietas na recria de jundiá proporcionam bom rendimento de carcaça e de partes comestíveis. E, as rações contendo óleo de canola possibilitam menor deposição de gordura no filé de juvenis de jundiá em nível de 5%

    Improved quality of online education using prioritized multi-agent reinforcement learning for video traffic scheduling

    Get PDF
    The recent global pandemic has transformed the way education is delivered, increasing the importance of videobased online learning. However, this puts a significant pressure on the underlying communication networks and the limited available bandwidth needs to be intelligently allocated to support a much higher transmission load, including video-based services. In this context, this paper proposes a Machine Learning (ML)-based solution that dynamically prioritizes content viewers with heterogeneous video services to increase their Quality of Service (QoS) and perceived Quality of Experience (QoE). The proposed approach makes use of the novel Prioritized Multi- Agent Reinforcement Learning solution (PriMARL) to decide the prioritization order of the video-based services based on networking conditions. However, the performance in terms of QoS and QoE provisioning to learners with different profiles and networking conditions depends on the type of scheduler employed in the frequency domain to conduct the scheduling and the radio resource allocation. To decide the best approach to be followed, we employ the proposed PriMARL solution with different types of scheduling rules and compare them with other state-of-theart solutions in terms of throughput, delay, packet loss, Peak Signal-to-Noise Ratio (PSNR), and Mean Opinion Score (MOS) for different traffic loads and characteristics. We show that the proposed solution achieves the best user QoE results

    Generalized Kahler Geometry from supersymmetric sigma models

    Full text link
    We give a physical derivation of generalized Kahler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri regarding the equivalence between generalized Kahler geometry and the bi-hermitean geometry of Gates-Hull-Rocek. When cast in the language of supersymmetric sigma models, this relation maps precisely to that between the Lagrangian and the Hamiltonian formalisms. We also discuss topological twist in this context.Comment: 18 page

    Exercise prescription to improve clinical practice on cancer patients suffering chemotherapy-induced peripheral neuropathy undergoing treatment: a systematic review

    Get PDF
    This document aims to summarize and analyze systematically the current body of evidence about the effects of specific exercise proto- cols on physical function, balance control and quality of life in patients with peripheral neuropathy (PNP) induced by chemotherapy. Methods: Systematic Review, Literature survey Specific terms were identified for the literature research in MEDLINE, Scopus, Bandolier, PEDro, and Web of Science. Only studies pub- lished in peer-reviewed journals written in English language were considered. Four manuscripts were classified as eligible with 88 total participants, with an average of 57.1 years old. Quality appraisal classified two studies as high quality investigations while two with low quality. Results were summarized in the following domains: \u201cCIPN symptoms\u201d, \u201cStatic balance control\u201d, \u201cDynamic balance control\u201d, \u201cQuali- ty of life and Physical function\u201d. Results Specific exercise protocols were able to counteract common symptoms of chemotherapy-induced peripheral neuropathy (CIPN) during chemotherapy treatments. Significant improvements were detected on postural control. Additionally, patients\u2019 quality of life and inde- pendence were found ameliorated after exercise sessions, together with reductions on altered sensations and in other peripheral neu- ropathy symptoms. Combined exercise protocols including endurance, strength and sensorimotor training showed larger improvements. Conclusions Exercise prescriptions for cancer patients undergoing chemotherapy with CIPN symptoms should be recommended since these exercise interventions appeared as feasible and have been demonstrated as useful tools to counteract some common side effects of chemother- apeutic agents
    corecore