1,039 research outputs found
Age-Related Gene Expression Differences in Monocytes from Human Neonates, Young Adults, and Older Adults.
A variety of age-related differences in the innate and adaptive immune systems have been proposed to contribute to the increased susceptibility to infection of human neonates and older adults. The emergence of RNA sequencing (RNA-seq) provides an opportunity to obtain an unbiased, comprehensive, and quantitative view of gene expression differences in defined cell types from different age groups. An examination of ex vivo human monocyte responses to lipopolysaccharide stimulation or Listeria monocytogenes infection by RNA-seq revealed extensive similarities between neonates, young adults, and older adults, with an unexpectedly small number of genes exhibiting statistically significant age-dependent differences. By examining the differentially induced genes in the context of transcription factor binding motifs and RNA-seq data sets from mutant mouse strains, a previously described deficiency in interferon response factor-3 activity could be implicated in most of the differences between newborns and young adults. Contrary to these observations, older adults exhibited elevated expression of inflammatory genes at baseline, yet the responses following stimulation correlated more closely with those observed in younger adults. Notably, major differences in the expression of constitutively expressed genes were not observed, suggesting that the age-related differences are driven by environmental influences rather than cell-autonomous differences in monocyte development
CAgNVAS II. Proper Motions in the sub-kiloparsec Jet of 3C 78: Novel Constraints on the Physical Nature of Relativistic Jets
Jets from active galactic nuclei are thought to play a role in the evolution
of their host and local environments, but a detailed prescription is limited by
the understanding of the jets themselves. Proper motion studies of compact
bright components in radio jets can be used to produce model-independent
constraints on their Lorentz factor, necessary to understand the quantity of
energy deposited in the inter-galactic medium. We present our initial work on
the jet of radio-galaxy 3C~78, as part of CAgNVAS (Catalogue of proper motions
in Active galactic Nuclei using Very Large Array Studies), with a goal of
constraining nature of jet plasma on larger ( parsec) scales. In 3C~78 we
find three prominent knots (A, B and C), where knot B undergoes subluminal
longitudinal motion ( at 200 pc), while knot C undergoes
extreme (apparent) backward motion and eventual forward motion (,
, at 300 pc). Assuming knots are shocks, we infer the bulk speeds
from the pattern motion of Knots B and C. We model the spectral energy
distribution (SED) of the large-scale jet and observe that a physically
motivated two-zone model can explain most of the observed emission. We also
find that the jet profile remains approximately conical from parsec to
kiloparsec scales. Using the parsec-scale speed from VLBI studies ()
and the derived bulk speeds, we find that the jet undergoes bulk acceleration
between the parsec and the kiloparsec scales providing the first direct
evidence of jet acceleration in a conical and matter-dominated jet.Comment: 18 pages, 14 figure
An Evolutionary Method for the Minimum Toll Booth Problem: the Methodology
This paper considers the minimum toll booth problem (MINTB) for determining a tolling strategy in a transportation network that requires the least number of toll locations, and simultaneously causes the most efficient use of the network. The paper develops a methodology for using the genetic algorithm to solve MINTB and presents the algorithm GAMINTB. The proposed method is tested and validated through a computational study with six example networks. Additional numerical test discovers some interesting properties for the proposed method, and provides guidelines for further application of the GAMINTB
Pdf modeling for premixed turbulent combustion based on the properties of iso-concentration surfaces
In premixed turbulent flames the presence of intense mixing zones located in front of and behind the flame surface leads to a requirement to study the behavior of iso-concentration surfaces defined for all values of the progress variable (equal to unity in burnt gases and to zero in fresh mixtures). To support this study, some theoretical and mathematical tools devoted to level surfaces are first developed. Then a database of direct numerical simulations of turbulent premixed flames is generated and used to investigate the internal structure of the flame brush, and a new pdf model based on the properties of iso-surfaces is proposed
The Clustering of X-ray Luminous Quasars
The clustering of active galactic nuclei (AGN) sheds light on their typical
large (Mpc-scale) environments, which can constrain the growth and evolution of
supermassive black holes. Here we measure the clustering of luminous
X-ray-selected AGN in the Stripe 82X and XMM-XXL-North surveys around the peak
epoch of black hole growth, in order to investigate the dependence of
luminosity on large-scale AGN environment. We compute the auto-correlation
function of AGN in two luminosity bins, erg
s at and erg s at ,
and calculate the AGN bias taking into account the redshift distribution of the
sources using three different methods. Our results show that while the less
luminous sample has an inferred typical halo mass that is smaller than for the
more luminous AGN, the host halo mass may be less dependent on luminosity than
suggested in previous work. Focusing on the luminous sample, we calculate a
typical host halo mass of M, which is similar
to previous measurements of moderate-luminosity X-ray AGN and significantly
larger than the values found for optical quasars of similar luminosities and
redshifts. We suggest that the clustering differences between different AGN
selection techniques are dominated by selection biases, and not due to a
dependence on AGN luminosity. We discuss the limitations of inferring AGN
triggering mechanisms from halo masses derived by large-scale bias.Comment: Accepted for publication in Ap
Identifying barriers to vaccination intention at walk-in vaccination facilities in deprived neighbourhoods:A cross-sectional survey
Objectives: Low COVID-19 vaccination adherence in deprived neighbourhoods is problematic since the prevalence of chronic diseases associated with mortality rates due to COVID-19 is higher in these populations. The aim of this study is to provide an insight about beliefs and considerations relating to vaccination intention among inhabitants of deprived neighbourhoods in the Netherlands. Design: Cross-sectional survey. Setting: Easily accessible vaccination facilities at markets in deprived neighbourhoods in the Netherlands. Participants: Participants were recruited at three vaccination facilities that were set up at markets in deprived neighbourhoods in Rotterdam. A total of 124 surveys were retained for analysis. Main outcome measure: Intention to get vaccinated against COVID-19. Results: The survey was filled out by 124 respondents; 62 % had - prior to visiting the easily accessible locations - intended to get a COVID-19 vaccine and 38 % were hesitant (22.3 % had doubts and 15.7 % did not plan to get vaccinated). Many people mentioned the convenience of an easily accessible location nearby. At the bivariate level, the influence of information from the family was associated with vaccination intention (p < 0.01). In a logistic regression model, both fear of vaccination and fear of side-effects were significantly associated with vaccination intention (ORs 0.56 (CI 0.35–0.89) and 0.47 (CI 0.30–0.73)). Conclusion: The accessibility of a vaccination facility, family influence and fear are relevant factors for the intention to get vaccinated against COVID-19 in people living in deprived neighbourhoods. Interventions should address these factors in order to increase vaccination uptake.</p
Relationship between cellular response and behavioral variability in bacterial chemotaxis
Bacterial chemotaxis in Escherichia coli is a canonical system for the study
of signal transduction. A remarkable feature of this system is the coexistence
of precise adaptation in population with large fluctuating cellular behavior in
single cells (Korobkova et al. 2004, Nature, 428, 574). Using a stochastic
model, we found that the large behavioral variability experimentally observed
in non-stimulated cells is a direct consequence of the architecture of this
adaptive system. Reversible covalent modification cycles, in which methylation
and demethylation reactions antagonistically regulate the activity of
receptor-kinase complexes, operate outside the region of first-order kinetics.
As a result, the receptor-kinase that governs cellular behavior exhibits a
sigmoidal activation curve. This curve simultaneously amplifies the inherent
stochastic fluctuations in the system and lengthens the relaxation time in
response to stimulus. Because stochastic fluctuations cause large behavioral
variability and the relaxation time governs the average duration of runs in
response to small stimuli, cells with the greatest fluctuating behavior also
display the largest chemotactic response. Finally, Large-scale simulations of
digital bacteria suggest that the chemotaxis network is tuned to simultaneously
optimize the random spread of cells in absence of nutrients and the cellular
response to gradients of attractant.Comment: 15 pages, 4 figures, Supporting information available here
http://cluzel.uchicago.edu/data/emonet/arxiv_070531_supp.pd
Global versus local billiard level dynamics: The limits of universality
Level dynamics measurements have been performed in a Sinai microwave billiard
as a function of a single length, as well as in rectangular billiards with
randomly distributed disks as a function of the position of one disk. In the
first case the field distribution is changed globally, and velocity
distributions and autocorrelation functions are well described by universal
functions derived by Simons and Altshuler. In the second case the field
distribution is changed locally. Here another type of universal correlations is
observed. It can be derived under the assumption that chaotic wave functions
may be described by a random superposition of plane waves
Influence of hydrodynamics on many-particle diffusion in 2D colloidal suspensions
We study many-particle diffusion in 2D colloidal suspensions with full
hydrodynamic interactions through a novel mesoscopic simulation technique. We
focus on the behaviour of the effective scaled tracer and collective diffusion
coefficients and , where is the
single-particle diffusion coefficient, as a function of the density of the
colloids . At low Schmidt numbers , we find that
hydrodynamics has essentially no effect on the behaviour of . At
larger , is enhanced at all densities, although the
differences compared to the case without hydrodynamics are minor. The
collective diffusion coefficient, on the other hand, is much more strongly
coupled to hydrodynamical conservation laws and is distinctly different from
the purely dissipative case
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