1,065 research outputs found
Global well-posedness and asymptotic behavior in Besov-Morrey spaces for chemotaxis-Navier-Stokes fluids
In this work we consider the Keller-Segel system coupled with Navier-Stokes
equations in for . We prove the global well-posedness
with small initial data in Besov-Morrey spaces. Our initial data class extends
previous ones found in the literature such as that obtained by
Kozono-Miura-Sugiyama (J. Funct. Anal. 2016). It allows to consider initial
cell density and fluid velocity concentrated on smooth curves or at points
depending on the spatial dimension. Self-similar solutions are obtained
depending on the homogeneity of the initial data and considering the case of
chemical attractant without degradation rate. Moreover, we analyze the
asymptotic stability of solutions at infinity and obtain a class of
asymptotically self-similar ones.Comment: 22 pages. Some typos have been corrected. Some references have been
updated/correcte
A young stellar environment for the superluminous supernova PTF12dam
The progenitors of super luminous supernovae (SLSNe) are still a mystery.
Hydrogen-poor SLSN hosts are often highly star-forming dwarf galaxies and the
majority belongs to the class of extreme emission line galaxies hosting young
and highly star-forming stellar populations. Here we present a resolved
long-slit study of the host of the hydrogen-poor SLSN PTF12dam probing the kpc
environment of the SN site to determine the age of the progenitor. The galaxy
is a "tadpole" with uniform properties and the SN occurred in a star-forming
region in the head of the tadpole. The galaxy experienced a recent star-burst
superimposed on an underlying old stellar population. We measure a very young
stellar population at the SN site with an age of ~3 Myr and a metallicity of
12+log(O/H)=8.0 at the SN site but do not observe any WR features. The
progenitor of PTF12dam must have been a massive star of at least 60 M_solar and
one of the first stars exploding as a SN in this extremely young starburst.Comment: submitted to MNRAS letters. 5 pages, 3 figures, supplementary
material: 2 figures, 2 table
Active Transcriptional Repression by the Rb–E2F Complex Mediates G1 Arrest Triggered by p16INK4a, TGFβ, and Contact Inhibition
AbstractRb inhibits progression from G1 to S phase of the cell cycle. It associates with a number of cellular proteins; however, the nature of these interactions and their relative significance in cell cycle regulation are still unclear. We present evidence that Rb must normally interact with the E2F family of transcription factors to arrest cells in G1, and that this arrest results from active transcriptional repression by the Rb–E2F complex, not from inactivation of E2F. Thus, a major role of E2F in cell cycle regulation is assembly of this repressor complex. We demonstrate that active repression by Rb–E2F mediates the G1 arrest triggered by TGFβ, p16INK4a, and contact inhibition
Mixing and transport of water in a karst catchment: a case study from precipitation via seepage to the spring
One of the best-known and largest karst areas in Germany, the Blautopf Catchment, offers unique access to waters of the unsaturated zone through a large cave system. It was investigated with stable isotopes (<sup>18</sup>O/<sup>16</sup>O and D/H ratios expressed in permille = &permil;) in precipitation, seepage- and groundwater as tracers for water flow, mixing, and storage. The precipitation showed a distinct seasonality with &delta;<sup>18</sup>O values between &minus;2.9 and &minus;24.6&permil; during summer and winter, respectively. However, the isotope signals in seepage water in the caves as well as the discharge were almost completely buffered and ranged around an average &delta;<sup>18</sup>O value of &minus;10&permil;. This value was also close to the long-term average value of local precipitation, &minus;9.3&permil;. The homogeneous isotopic composition of the Blautopf Spring was unexpected, as its highly variable discharge (0.3 to 32 m<sup>3</sup> s<sup>&minus;1</sup>) is typical for a fast responsive karst system. These isotopic similarities could be explained by nearly complete mixing of the water already in the vadose zone. The data set therefore presents a case study to narrow down zones of mixing in karst catchments. It also confirms the minor role of the fast conduit system in the water balance of the Blautopf Catchment
Storage and transport in cave seepage- and groundwater in a South German karst system
International audienceWe investigated one of the best-known and second largest karst areas in Germany (Blautopf Catchment) that offers a unique access waters of the unsaturated zone through a large cave system. As tracers for water flow and storage we measured stable isotopes (18O/16O and D/H ratios) in precipitation, seepage- and groundwater. The precipitation showed a distinct seasonal cycle with ?18O values between ?2.6 and ?22.6? during summer and winter, respectively. However, the isotope signals in seepage water in the caves as well as the discharge were completely buffered and ranged around an average ?18O value of ?10?. This value also matched the long-term average of the precipitation. In addition, the homogeneous isotopic composition of the Blautopf Spring was against expectation for its highly variable discharge (0.3 to 32 m3 s?1) that is typical for a fast responsive karst system. We explain the isotopic similarity between cave seepage and the Blautopf Spring (as an integral signal for groundwater) by nearly complete mixing of the water already in the vadose zone. The latter can be divided into the compartments soil, epikarst and rock matrix that all have good storage capacities and also allow diffusive exchange of solutes between mobile and less mobile matrix water. The above approach revealed new aspects about turnover and flow paths of the infiltrated water and thus helps to constrain the risk by pollution to the groundwater
The host of the Type I SLSN 2017egm: A young, sub-solar metallicity environment in a massive spiral galaxy
Here we present an integral-field study of the massive, high-metallicity
spiral NGC 3191, the host of SN 2017egm, the closest SLSN Type I to date. We
use data from PMAS/CAHA and the public MaNGA survey to shed light on the
properties of the SLSN site and the origin of star-formation in this
non-starburst spiral galaxy. We map the physical properties different
\ion{H}{II} regions throughout the galaxy and characterize their stellar
populations using the STARLIGHT fitting code. Kinematical information allows to
study a possible interaction with its neighbouring galaxy as the origin of
recent star formation activity which could have caused the SLSN. NGC 3191 shows
intense star-formation in the western part with three large SF regions of low
metallicity. The central regions of the host have a higher metallicity, lower
specific star-formation rate and lower ionization. Modeling the stellar
populations gives a different picture: The SLSN region has two dominant stellar
populations with different ages, the youngest one with an age of 2-10 Myr and
lower metallicity, likely the population from which the SN progenitor
originated. Emission line kinematics of NGC 3191 show indications of
interaction with its neighbour MCG+08-19-017 at 45 kpc, which might be
responsible for the recent starburst. In fact, this galaxy pair has in total
hosted 4 SNe, 1988B (Type Ia), SN 2003ds (Type Ic in MCG+08-19-017), PTF10bgl
(SLSN-Type II) and 2017egm, underlying the enhanced SF in both galaxies due to
interaction. Our study shows that one has to be careful interpreting global
host and even gas properties without looking at the stellar population history
of the region. SLSNe seem to still be consistent with massive stars ( 20
M) requiring low () metallicity and those environments
can also occur in massive, late-type galaxies but not necessarily starbursts.Comment: Accepted for publication in A&A, 13 pages, 11 figures, 7 tables.
Abstract has been reduced to match arXiv form requirement
Padronização de perfil metabólico em bovinos tratados com ivermectina por meio da urina em ressonância magnética nuclear (RMN).
O controle de Rhipicephalus (Boophilus) microplus ocorre por meio de antiparasitários e a contaminação dos produtos de origem animal com resÃduos é uma grande preocupação para os agentes de saúde pública e controle ambiental. Metabolômica e Metabonômica são duas ferramentas utilizadas no panorama da bioquÃmica moderna. Enquanto a primeira refere-se ao estudo sistemático dos nÃveis de metabólitos de um organismo, a última correlaciona as alterações destes nÃveis a estÃmulos externos, como doenças e mudanças alimentares. Neste trabalho, utilizou-se a Metabonômica para tentar estabelecer um padrão no perfil metabólico de animais tratados com ivermectina, por meio da RMN de alta resolução na Embrapa Instrumentação Agropecuária. Amostras de urina foram colhidas de 12 bezerras Holandesas da Embrapa Pecuária Sudeste, 0, 3 e 6 h pós tratamento com ivermectina 4% subcutânea (Master LP®, Ouro Fino), na dose de 1 mL/50 Kg e congeladas a -40°C para posterior análise
- …