6,574 research outputs found
Efficient inference for genetic association studies with multiple outcomes
Combined inference for heterogeneous high-dimensional data is critical in
modern biology, where clinical and various kinds of molecular data may be
available from a single study. Classical genetic association studies regress a
single clinical outcome on many genetic variants one by one, but there is an
increasing demand for joint analysis of many molecular outcomes and genetic
variants in order to unravel functional interactions. Unfortunately, most
existing approaches to joint modelling are either too simplistic to be powerful
or are impracticable for computational reasons. Inspired by Richardson et al.
(2010, Bayesian Statistics 9), we consider a sparse multivariate regression
model that allows simultaneous selection of predictors and associated
responses. As Markov chain Monte Carlo (MCMC) inference on such models can be
prohibitively slow when the number of genetic variants exceeds a few thousand,
we propose a variational inference approach which produces posterior
information very close to that of MCMC inference, at a much reduced
computational cost. Extensive numerical experiments show that our approach
outperforms popular variable selection methods and tailored Bayesian
procedures, dealing within hours with problems involving hundreds of thousands
of genetic variants and tens to hundreds of clinical or molecular outcomes
The eigenpairs of a Sylvester-Kac type matrix associated with a simple model for one-dimensional deposition and evaporation
A straightforward model for deposition and evaporation on discrete cells of a
finite array of any dimension leads to a matrix equation involving a
Sylvester-Kac type matrix. The eigenvalues and eigenvectors of the general
matrix are determined for an arbitrary number of cells. A variety of models to
which this solution may be applied are discussed.Comment: 7 pages, no figure
Microwave-assisted synthesis of a MK2 inhibitor by Suzuki-Miyaura coupling for study in Werner syndrome cells
Microwave-assisted Suzuki-Miyaura cross-coupling reactions have been employed towards the synthesis of three different MAPKAPK2 (MK2) inhibitors to study accelerated aging in Werner syndrome (WS) cells, including the cross-coupling of a 2-chloroquinoline with a 3-pyridinylboronic acid, the coupling of an aryl bromide with an indolylboronic acid and the reaction of a 3-amino-4-bromopyrazole with 4-carbamoylphenylboronic acid. In all of these processes, the Suzuki-Miyaura reaction was fast and relatively efficient using a palladium catalyst under microwave irradiation. The process was incorporated into a rapid 3-step microwave-assisted method for the synthesis of a MK2 inhibitor involving 3-aminopyrazole formation, pyrazole C-4 bromination using N-bromosuccinimide (NBS), and Suzuki-Miyaura cross-coupling of the pyrazolyl bromide with 4-carbamoylphenylboronic acid to give the target 4-arylpyrazole in 35% overall yield, suitable for study in WS cells
Reforming the Placement of Transfer Students in Introductory Level Mathematics Courses
Transfer has become a significant pathway for obtaining a bachelor’s degree from four-year institutions. As a result, higher education institutions are faced with an increasing population of transfer students with varied academic backgrounds and readiness levels. Determining the placement of transfer students in the appropriate introductory-level mathematics course presents a distinctive challenge, and has not been the focus of many studies. In response, this article offers an analysis of the difficulties associated with the placement of transfer students and of the variety of practices regarding placement across select institutions. A narrative describing the placement system for transfer students adopted at a public four-year university in Massachusetts, as well as recommendations for other institutions for the implementation of a smooth, efficient and transparent mathematics placement system for transfer students, is provided
Analysis of noise-induced transitions from regular to chaotic oscillations in the Chen system
The stochastically perturbed Chen system is studied within the parameter region which permits both regular and chaotic oscillations. As noise intensity increases and passes some threshold value, noise-induced hopping between close portions of the stochastic cycle can be observed. Through these transitions, the stochastic cycle is deformed to be a stochastic attractor that looks like chaotic. In this paper for investigation of these transitions, a constructive method based on the stochastic sensitivity function technique with confidence ellipses is suggested and discussed in detail. Analyzing a mutual arrangement of these ellipses, we estimate the threshold noise intensity corresponding to chaotization of the stochastic attractor. Capabilities of this geometric method for detailed analysis of the noise-induced hopping which generates chaos are demonstrated on the stochastic Chen system. © 2012 American Institute of Physics
A new chapter of healthy indoor air: antiviral air treatments
Aerosol transmission remains a major challenge for the control of respiratory viruses. To date, prevention strategies include masks, vaccinations, physical distancing, travel restrictions, and lockdowns. Such measures are effective but come with heavy societal burdens and rely on public compliance. Additionally, most are simply not suitable as long-term measures. Other strategies evolve around the concept of improved indoor air quality and involve ventilation, relative humidity (RH) control, and air filtration. Unfortunately, natural ventilation increases exposure to airborne pollutants and vector-borne diseases, and incurs substantial energy losses in colder months. Mechanical ventilation concepts, including regular air changes and filtration, are effective but costly, and often require expensive engineering solutions and widespread renovations. Alternative options to reduce the spread of emerging and seasonal infections are sorely needed. In this issue of EMBO Molecular Medicine, Styles et al (2023) describe the use of propylene glycol (PG) to inactivate infectious bioaerosols and virus-containing droplets deposited on surfaces
Kerr Black Holes are Not Unique to General Relativity
Considerable attention has recently focused on gravity theories obtained by
extending general relativity with additional scalar, vector, or tensor degrees
of freedom. In this paper, we show that the black-hole solutions of these
theories are essentially indistinguishable from those of general relativity.
Thus, we conclude that a potential observational verification of the Kerr
metric around an astrophysical black hole cannot, in and of itself, be used to
distinguish between these theories. On the other hand, it remains true that
detection of deviations from the Kerr metric will signify the need for a major
change in our understanding of gravitational physics.Comment: 4 pages, Physical Review Letters in pres
Is there Quark Matter in (Low-Mass) Pulsars?
The effect of the QCD phase transition is studied for the mass-radius
relation of compact stars and for hot and dense matter at a given proton
fraction used as input in core-collapse supernova simulations. The phase
transitions to the 2SC and CFL color superconducting phases lead to stable
hybrid star configurations with a pure quark matter core. In supernova
explosions quark matter could be easily produced due to -equilibrium,
small proton fractions and nonvanishing temperatures. A low critical density
for the phase transition to quark matter is compatible with present pulsar mass
measurements.Comment: 4 pages, 3 figures, talk given at the QM2008 conference, Jaipur,
India, February 4-10, 2008, JPG in pres
The fern genus Pteridium in a trans Euro-Siberian perspective - a morphological synthesis
The taxonomy and distribution of Pteridium Gled. ex Scop, is present across the broad west-east span of the Euro-Siberian region. It is concluded that at least two species of Pteridium - true P. aquiiinum (L.) Kuhn and P
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