4,166 research outputs found
Branching Feller diffusion for cell division with parasite infection
We describe the evolution of the quantity of parasites in a population of
cells which divide in continuous-time. The quantity of parasites in a cell
follows a Feller diffusion, which is splitted randomly between the two daughter
cells when a division occurs. The cell division rate may depend on the quantity
of parasites inside the cell and we are interested in the cases of constant or
monotone division rate. We first determine the asymptotic behavior of the
quantity of parasites in a cell line, which follows a Feller diffusion with
multiplicative jumps. We then consider the evolution of the infection of the
cell population and give criteria to determine whether the proportion of
infected cells goes to zero (recovery) or if a positive proportion of cells
becomes largely infected (proliferation of parasites inside the cells)
Limit theorems for Markov processes indexed by continuous time Galton--Watson trees
We study the evolution of a particle system whose genealogy is given by a
supercritical continuous time Galton--Watson tree. The particles move
independently according to a Markov process and when a branching event occurs,
the offspring locations depend on the position of the mother and the number of
offspring. We prove a law of large numbers for the empirical measure of
individuals alive at time t. This relies on a probabilistic interpretation of
its intensity by mean of an auxiliary process. The latter has the same
generator as the Markov process along the branches plus additional jumps,
associated with branching events of accelerated rate and biased distribution.
This comes from the fact that choosing an individual uniformly at time t favors
lineages with more branching events and larger offspring number. The central
limit theorem is considered on a special case. Several examples are developed,
including applications to splitting diffusions, cellular aging, branching
L\'{e}vy processes.Comment: Published in at http://dx.doi.org/10.1214/10-AAP757 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Checkpoint inhibitors and the gut
Checkpoint inhibitors have revolutionized treatments in modern oncology, including many conditions previously relegated to palliative therapies only. However, emerging recognition of checkpoint inhibitor-related adverse events has complicated the status of checkpoint inhibitor-related therapies. This review article discusses gastrointestinal adverse events as a result of checkpoint
inhibitor therapy, as well as limitations of current guidelines, thus providing recommendations for guideline revision and future study direction
Nonparametric estimation of the fragmentation kernel based on a PDE stationary distribution approximation
We consider a stochastic individual-based model in continuous time to
describe a size-structured population for cell divisions. This model is
motivated by the detection of cellular aging in biology. We address here the
problem of nonparametric estimation of the kernel ruling the divisions based on
the eigenvalue problem related to the asymptotic behavior in large population.
This inverse problem involves a multiplicative deconvolution operator. Using
Fourier technics we derive a nonparametric estimator whose consistency is
studied. The main difficulty comes from the non-standard equations connecting
the Fourier transforms of the kernel and the parameters of the model. A
numerical study is carried out and we pay special attention to the derivation
of bandwidths by using resampling
Integer Complexity Generalizations in Various Rings
In this paper, we investigate generalizations of the Mahler-Popkens
complexity of integers. Specifically, we generalize to -th roots of unity,
polynomials over the naturals, and the integers mod . In cyclotomic rings,
we establish upper and lower bounds for integer complexity, investigate the
complexity of roots of unity using cyclotomic polynomials, and introduce a
concept of "minimality.'' In polynomials over the naturals, we establish bounds
on the sizes of complexity classes and establish a trivial but useful upper
bound. In the integers mod , we introduce the concepts of "inefficiency'',
"resilience'', and "modified complexity.'' In hopes of improving the upper
bound on the complexity of the most complex element mod , we also use graphs
to visualize complexity in these finite rings.Comment: 44 pages, 11 figures, Research Lab from PROMY
A comprehensive model of the optical spectra of carbon nanotubes on substrate by polarized microscopy
Polarized optical microscopy and spectroscopy are progressively becoming key
methods for the high-throughput characterization of individual carbon nanotubes
(CNTs) and other one-dimensional nanostructures, on substrate and in devices.
The optical response of CNTs on substrate in cross polarization experiments is
usually limited by the polarization conservation of the optical elements in the
experimental setup. We developed a theoretical model taking into account the
depolarization by the setup and the optical response of the substrate. We show
that proper modelization of the experimental data requires to take into account
both non-coherent and coherent light depolarization by the optical elements. We
also show how the nanotube signal can be decoupled from the complex reflection
factor of the anti-reflection substrate which is commonly used to enhance the
optical contrast. Finally, we describe an experimental protocol to extract the
depolarization parameters and the complex nanotube susceptibility, and how it
can improve the chirality assignment of individual carbon nanotubes in complex
cases.Comment: 10 pages, 7 Figures, submitted to PRB. A supplementary information
completes this pape
Defective phagocytic corpse processing results in neurodegeneration and can be rescued by TORC1 activation
This work was supported by NIH Grants R01 GM094452 (K.M.) and F31 GM099425 (J.I.E.), BU Alzheimer's Disease Core Center NIH Grant P30 AG13846, Boston University Undergraduate Research Opportunities Program grants (J.A.T., V.S.), and NIH Grant R01 AG044113 to M.B.F. We thank the Bloomington Stock Center, TRiP at Harvard Medical School, the Kyoto Drosophila Genetic Resource Center, Estee Kurant, Eric Baehrecke, Marc Freeman, and Mary Logan for fly strains. We thank Todd Blute for assistance with electron microscopy and the Developmental Studies Hybridoma Bank for antibodies. (R01 GM094452 - NIH; F31 GM099425 - NIH; R01 AG044113 - NIH; P30 AG13846 - BU Alzheimer's Disease Core Center NIH Grant; Boston University Undergraduate Research Opportunities Program)https://www.jneurosci.org/content/36/11/3170.longPublished versionPublished versio
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