74 research outputs found
Accretion, Outflows, and Winds of Magnetized Stars
Many types of stars have strong magnetic fields that can dynamically
influence the flow of circumstellar matter. In stars with accretion disks, the
stellar magnetic field can truncate the inner disk and determine the paths that
matter can take to flow onto the star. These paths are different in stars with
different magnetospheres and periods of rotation. External field lines of the
magnetosphere may inflate and produce favorable conditions for outflows from
the disk-magnetosphere boundary. Outflows can be particularly strong in the
propeller regime, wherein a star rotates more rapidly than the inner disk.
Outflows may also form at the disk-magnetosphere boundary of slowly rotating
stars, if the magnetosphere is compressed by the accreting matter. In isolated,
strongly magnetized stars, the magnetic field can influence formation and/or
propagation of stellar wind outflows. Winds from low-mass, solar-type stars may
be either thermally or magnetically driven, while winds from massive, luminous
O and B type stars are radiatively driven. In all of these cases, the magnetic
field influences matter flow from the stars and determines many observational
properties. In this chapter we review recent studies of accretion, outflows,
and winds of magnetized stars with a focus on three main topics: (1) accretion
onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and
(3) winds from isolated massive magnetized stars. We show results obtained from
global magnetohydrodynamic simulations and, in a number of cases compare global
simulations with observations.Comment: 60 pages, 44 figure
Emergence of phlebotomine sandflies (Diptera: Psychodidade) in non-flooded forest floor in Central Amazon, Brazil: a modified emergence trap model
Information concerning the potential natural breeding sites of phlebotomine sandflies are of high epidemiological importance. However, few studies have been conducted on the subject. This is due especially to the difficulties in finding as well as extracting immature sandflies that develop in the soil and organic matter of the forest floor. In the present study, a modified emergence trap model was tested in order to find potential breeding sites. This model was tested in the Pitinga Village, situated in the Presidente Figueredo municipality, in the State of Amazonas. Twenty-seven individuals belonging to nine species (Lutzomyia umbratilis,L. monstruosa,L. ayrozai,L. anduzei,L. trichopyga,L. davisi,L. geniculata,L. georgii e L. saulensis.) were collected. Lutzomyia umbratilis showed the highest number of individuals (37.1%) of all species captured in the area. The phlebotomine productivity was estimated as 2.2 sandflies per 100 mÂČ/day. September showed the highest density of individuals, with a productivity of 5.8.InformaçÔes acerca de potenciais criadouros naturais de flebotomĂneos sempre foram de fundamental interesse epidemiolĂłgico. Contudo, sĂŁo poucas as informaçÔes advindas dos diversos estudos realizados atĂ© o momento. Isto se deve principalmente Ă s dificuldades de localização e extração dos imaturos que se desenvolvem no solo e matĂ©ria orgĂąnica do chĂŁo de florestas. No presente estudo o modelo modificado de armadilha de emergĂȘncia foi testado na Vila do Pitinga, municĂpio de Presidente Figueiredo, Estado do Amazonas, a fim de localizar potenciais criadouros naturais. Vinte e sete indivĂduos de nove espĂ©cies (Lutzomyia umbratilis,L. monstruosa,L. ayrozai,L. anduzei,L. trichopyga,L. davisi,L. geniculata,L. georgii e L. saulensis) foram coletados. Lutzomyia umbratilis foi a espĂ©cie com maior nĂșmero de indivĂduos, 10, representando 37,1% do total. A produção de flebotomĂneos foi estimada em 2,2 flebotomĂneos por 100 mÂČ por dia. Em setembro, mĂȘs com maior nĂșmero de indivĂduos, esta produção foi de 5,8
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