4,743 research outputs found
A variable corona during the transition from type-C to type-B quasi-periodic oscillations in the black hole X-ray binary MAXI J1820+070
We analyze a Neutron Star Interior Composition Explorer (NICER) observation
of the black hole X-ray binary MAXI J1820+070 during a transition from type-C
to type-B quasi-periodic oscillations (QPOs). We find that below ~2 keV, for
the type-B QPOs the rms amplitude is lower and the magnitude of the phase lags
is larger than for the type-C QPOs. Above that energy, the rms and phase-lag
spectra of the type-B and type-C QPOs are consistent with being the same. We
perform a joint fit of the time-averaged spectra of the source, and the rms and
phase-lag spectra of the QPOs with the time-dependent Comptonization model
vkompth to study the geometry of the corona during the transition. We find that
the data can be well-fitted with a model consisting of a small and a large
corona that are physically connected. The sizes of the small and large coronae
increase gradually during the type-C QPO phase whereas they decrease abruptly
at the transition to type-B QPO. At the same time, the inner radius of the disc
moves inward at the QPO transition. Combined with simultaneous radio
observations showing that discrete jet ejections happen around the time of the
QPO transition, we propose that a corona that expands horizontally during the
type-C QPO phase, from ~10^{4} km (~800 Rg) to ~10^{5} km (~8000 Rg) overlying
the accretion disc, transforms into a vertical jet-like corona extending over
~10^{4} km (~800 Rg) during the type-B QPO phase.Comment: 22 pages, 16 figures, 2 tables, accepted for publication in MNRA
ESTUDIO DE LA MERCADOTECNIA EN LA COMPRA Y VENTA DE MIEL: UN ANÃLISIS FACTORIAL
This research describes and analyzes the commercial actions being conducted in six groups of producers bee located on the periphery of the state capital of Puebla, Mexico. We study the guidelines that have developed around the marketing as a discipline dedicated to analysis and implications of commercial actions, taking as a hub consumer preferences. There is some use of marketing tools in selling practices carried out by small groups of producers of honey, with the implementation of factor analysis. We found that the actions that develop commercial producers and honey producers are limited to continue with their daily practice of selling what they produce rather than mainstream approach mercadológico to produce what consumers are willing to buy and pay. The orientation of marketing that is focused primarily applied to the production phase, to ensure the acquisition of its product and promoting its sale, even without incorporating current trends show that the needs and preferences of consumers and the market where participating.Honey, marketing, commercial actions, customers., Agribusiness,
Human Social Behavior and Demography Drive Patterns of Fine-Scale Dengue Transmission in Endemic Areas of Colombia
Dengue is known to transmit between humans and A. aegypti mosquitoes living in neighboring houses. Although transmission is thought to be highly heterogeneous in both space and time, little is known about the patterns and drivers of transmission in groups of houses in endemic settings. We carried out surveys of PCR positivity in children residing in 2-block patches of highly endemic cities of Colombia. We found high levels of heterogeneity in PCR positivity, varying from less than 30% in 8 of the 10 patches to 56 and 96%, with the latter patch containing 22 children simultaneously PCR positive (PCR22) for DEN2. We then used an agent-based model to assess the likely eco-epidemiological context of this observation. Our model, simulating daily dengue dynamics over a 20 year period in a single two block patch, suggests that the observed heterogeneity most likely derived from variation in the density of susceptible people. Two aspects of human adaptive behavior were critical to determining this density: external social relationships favoring viral introduction (by susceptible residents or infectious visitors) and immigration of households from non-endemic areas. External social relationships generating frequent viral introduction constituted a particularly strong constraint on susceptible densities, thereby limiting the potential for explosive outbreaks and dampening the impact of heightened vectorial capacity. Dengue transmission can be highly explosive locally, even in neighborhoods with significant immunity in the human population. Variation among neighborhoods in the density of local social networks and rural-to-urban migration is likely to produce significant fine-scale heterogeneity in dengue dynamics, constraining or amplifying the impacts of changes in mosquito populations and cross immunity between serotypes
Type-A quasi-periodic oscillation in the black hole transient MAXI J1348-630
We present a detailed analysis of the spectral and timing characteristics of a 7-Hz type-A quasi-periodic oscillation (QPO) detected in NICER observations of the black hole X-ray binary MAXI J1348-630 during its high-soft state. The QPO is broad and weak, with an integrated fractional rms amplitude of 0.9 per cent in the 0.5-10 keV band. Thanks to the large effective area of NICER, combined with the high flux of the source and a relatively long accumulative exposure time, we construct the first rms and phase-lag spectra for a type-A QPO. Our analysis reveals that the fractional rms amplitude of the QPO increases with energy from below 1 per cent at 1 keV to ∼3 per cent at 6 keV. The shape of the QPO spectrum is similar to that of the Comptonized component, suggesting that the Comptonized region is driving the variability. The phase lags at the QPO frequency are always soft taking the lowest energy as reference. By jointly fitting the time-averaged spectrum of the source and the rms and phase-lag spectra of the QPO with the time-dependent Comptonization model vkompthdk, we find that the radiative properties of the type-A QPO can be explained by a vertically extended Comptonized region with a size of ∼2300 km.</p
NSMCE2 suppresses cancer and aging in mice independently of its SUMO ligase activity.
The SMC5/6 complex is the least understood of SMC complexes. In yeast, smc5/6 mutants phenocopy mutations in sgs1, the BLM ortholog that is deficient in Bloom's syndrome (BS). We here show that NSMCE2 (Mms21, in Saccharomyces cerevisiae), an essential SUMO ligase of the SMC5/6 complex, suppresses cancer and aging in mice. Surprisingly, a mutation that compromises NSMCE2-dependent SUMOylation does not have a detectable impact on murine lifespan. In contrast, NSMCE2 deletion in adult mice leads to pathologies resembling those found in patients of BS. Moreover, and whereas NSMCE2 deletion does not have a detectable impact on DNA replication, NSMCE2-deficient cells also present the cellular hallmarks of BS such as increased recombination rates and an accumulation of micronuclei. Despite the similarities, NSMCE2 and BLM foci do not colocalize and concomitant deletion of Blm and Nsmce2 in B lymphocytes further increases recombination rates and is synthetic lethal due to severe chromosome mis-segregation. Our work reveals that SUMO- and BLM-independent activities of NSMCE2 limit recombination and facilitate segregation; functions of the SMC5/6 complex that are necessary to prevent cancer and aging in mice.The authors want to thank Jordi Torres and Mark O'Driscoll for comments on the manuscript. Work in OF laboratory related to this project was supported by Fundacion Botin, by Banco Santander through its Santander Universities Global Division and by grants from MINECO (SAF2011-23753 and SAF2014-57791-REDC), Howard Hughes Medical Institute, and the European Research Council (ERC-617840). Work in JM laboratory was funded by a grant from MINECO (BFU2013-49153P).S
Model reduction in the back step fluid–thermal problem with variable geometry
A methodology is presented to undertake the development of reduced-order models (ROMs) in variable geometry fluid–thermal problems using the method of snapshots. First, some snapshots are calculated in computational domains that vary in both shape and number of grid points. These snapshots are projected onto a so-called virtual grid (defined in a virtual geometry) using a smooth transformation. Proper orthogonal decomposition (POD) modes are obtained from the associated virtual snapshots and projected back onto the original grids, where they are used to define expansions of the flow variables. The associated POD mode amplitudes are obtained minimizing a residual, which is calculated in terms of the reconstructed solution. POD modes are calculated using only a part of the computational domain, which will be called the projection window, and the residual is defined using only a limited number of points of the computational domain. This methodology is illustrated addressing the problem of heat transfer downstream of a backward facing step in the 2-D steady, laminar regime, with three free parameters, namely the Reynolds number, the wall temperature, and the step height
Devenires de la Literatura y la Filosofía
Los textos aquí reunidos, que transitan de la filosofía a la literatura y viceversa, son un intento de pensar el devenir no como mero cambio, sino como un proceso inagotable que se opone al principio de no contradicción, que privilegia lo inacabado, lo indiferenciado, lo que se resiste a toda resolución permanente. Por ello mismo es también un devenir cargado de potencia, de posibilidades heterogéneas que pueden permitirnos salir de la Imagen del pensamiento y, así, pensar la diferencia.Universidad Autónoma del Estado de México y Ediciones y Gráficos Eón, S.A. de C.V
Extensive antimicrobial resistance mobilization via Multicopy Plasmid Encapsidation mediated by temperate phages
Objectives: To investigate the relevance of multicopy plasmids in antimicrobial resistance and assess their mobilization mediated by phage particles Methods: Several databases with complete sequences of plasmids and annotated genes were analysed. The 16S methyltransferase gene armA conferring high-level aminoglycoside resistance was used as a marker in eight different plasmids, from different incompatibility groups, and with differing sizes and plasmid copy numbers. All plasmids were transformed into Escherichia coli bearing one of four different lysogenic phages. Upon induction, encapsidation of armA in phage particles was evaluated using qRT-PCR and Southern blotting. Results: Multicopy plasmids carry a vast set of emerging clinically important antimicrobial resistance genes. However, 60% of these plasmids do not bear mobility (MOB) genes. When carried on these multicopy plasmids, mobilization of a marker gene armA into phage capsids was up to 10000 times more frequent than when it was encoded by a large plasmid with a low copy number. Conclusions: Multicopy plasmids and phages, two major mobile genetic elements (MGE) in bacteria, represent a novel high-efficiency transmission route of antimicrobial resistance genes that deserves further investigation
- …