54 research outputs found

    Origins of the Ambient Solar Wind: Implications for Space Weather

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    The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

    The Physics of Star Cluster Formation and Evolution

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    © 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe

    Meio modificado de cultura para caracterização de Salmonella lactose positiva A modified culture medium for the characterization of positive lactose strains of Salmonella

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    Foi desenvolvido um meio modificado de cultura para isolamento e caracterização de enterobactérias, visando especialmente salmonelas fermentadoras da lactose. No chamado "Meio modificado" as colônias das duas estirpes de Salmonella (lactose positivas e lactose negativas) apresentam a morfologia idêntica, o que não ocorre quando são empregados os meios rotineiros à base de lactose, para isolamento de enterobactérias. Esse meio é uma modificação do meio de Hektoen Enteric Agar, do qual retirou-se lactose e adicionou-se xilose e L-lisina. Foi verificado que há possibilidade de diferenciar-se os diversos grupos de enterobactérias, empregando um meio de cultura sem lactose e usando como sistema diferenciador xilose e L-lisina. O meio modificado foi também avaliado quantitativamente comparando o seu poder enriquecedor ou inibitório, ao dos meios de Hektoen Enteric Agar, Brilliant Green Agar e SS Agar para diferentes grupos de enterobactérias.<br>A modified culture medium was developed for the purpose of isolating and characterizing the enterobacterias, giving special attention to the Salmonella strains that ferment lactose. In this "Modified Medium" the colonies of the two strains of Salmonella show a morphological similarity. This does not occur with other culture media of enterobacteria, in which the basic carbohydrate is lactose. The Modified Medium is a modification of the Enteric Agar in which the lactose was substituted by xilose and L-lisine. It was verified that there is a possibility of differentiating between the different groups of enterobacteria by using a culture medium with no lactose and using xilose L-lisina as a differentiating system. The Modified Medium was also evaluated quantitatively comparing its enriching or inhibiting power with the Hektoen Enteric Agar, Brilliant Green Agar and the SS Agar media in relation to the different groups of enterobacteria

    Clinical effectiveness of mindfulness-based music therapy on improving emotional regulation in blind older women: A randomized controlled trial

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    BackgroundThis study aimed to investigate clinical effectiveness of a structured eight-week mindfulness-based music therapy (MBMT) program on improving mood regulation in older women with blindness. This investigation compared a MBMT group with a mindfulness intervention (MI) group and a control group.MethodsNinety-two older females with blindness from a residential setting in Hong Kong were recruited and randomly allocated to a MBMT (n=31), MI (n=30), or control (n=31) group. Psychological measurements regarding mood regulation and general mood states (namely, Difficulties in Emotion Regulation Scale [DERS], Geriatric Depression Scale [GDS], and Depression Anxiety Stress Scales-21), were taken at pretest and posttest. Outcome assessors were blinded to group assignment.ResultsData was analyzed based on intention-to-treat basis. At posttest, DERS scores in the MBMT group (mean differences and 95% confidence interval: 12.1, 5.5 to 18.8) and the MI group (7.2, 0.5 to 13.8) were lower than that in the control group. GDS scores in the MBMT group (2.9, 1.7 to 4.0) and the MI group (1.7, 0.6 to 2.9) were lower than those in the control group. Compared with the MI group, the MBMT group improved emotional awareness sub-scores in DERS (2.1, 0.2 to 4.1) and appeared to lower depression in GDS scores (1.1, -0.0 to 2.3; p = .053).ConclusionMBMT seems more beneficial than MI alone for improving emotional regulation in older women with blindness. The combination of mindfulness and music can generate a synergetic effect by enhancing both attention and appraisal components within the emotional-regulation process
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