143 research outputs found
Muonium-Antimuonium Oscillations in an extended Minimal Supersymmetric Standard Model with right-handed neutrinos
The electron and muon number violating muonium-antimuonium oscillation
process in an extended Minimal Supersymmetric Standard Model is investigated.
The Minimal Supersymmetric Standard Model is modified by the inclusion of three
right-handed neutrino superfields. While the model allows the neutrino mass
terms to mix among the different generations, the sneutrino and slepton mass
terms have only intra-generation lepton number violation but not
inter-generation lepton number mixing. So doing, the muonium-antimuonium
conversion can then be used to constrain those model parameters which avoid
further constraint from the decay bounds. For a wide range of
parameter values, the contributions to the muonium-antimuonium oscillation time
scale are at least two orders of magnitude below the sensivity of current
experiments. However, if the ratio of the two Higgs field VEVs, , is
very small, there is a limited possibility that the contributions are large
enough for the present experimental limit to provide an inequality relating
with the light neutrino mass scale which is generated by
see-saw mechanism. The resultant lower bound on as a function of
is more stringent than the analogous bounds arising from the muon and
electron anomalous magnetic moments as computed using this model.Comment: 29 pages, 7 figures, 3 tables, Late
SIVALHIPPUS PTYCHODUS AND SIVALHIPPUS PLATYODUS (PERISSODACTYLA, MAMMALIA) FROM THE LATE MIOCENE OF CHINA
Herein, the authors report on skulls, mandibles and postcranial specimens of two species of Chinese Sivalhippus, S. ptychodus and S. platyodus. We frame our description and analyses within the context of newly described characters of the cheek teeth of Hippotherium from the Pannonian C of the Vienna Basin, the oldest and most primitive Old World hipparions. Our report includes original skull, mandibular and limited postcranial material of Sivalhippus ptychodus and skulls and dentitions of Sivalhippus platyodus from the Paleontological Museum of Uppsala (PMU, Uppsala, Sweden), the American Museum of Natural History (AMNH, New York, USA) and the Licent Collection in Tianjin Natural History Museum (Tianjin, China). The skull, maxillary and mandibular material we attribute to Sivalhippus ptychodus and Sivalhippus platyodus exhibit some primitive features for Old World hipparions and synapamorphies of the face and dentition that unite it with the Sivalhippus clade. Our analysis shows that S. ptychodus and S. platyodus differ significantly from the Cormohipparion occidentale – Hippotherium primigenium clade. Species belonging to the Sivalhippus clade are found in IndoPakistan (S. nagriensis, S. theobaldi, S. perimensis and S. anwari), Libya and Kenya (S. turkanensis) and Uganda (S. macrodon). We hypothesize that the Sivalhippus clade originated in South Asia where it is earliest represented by Sivalhipus nagriensis, ca. 10.4 Ma and underwent range extension into Africa and China circa 9-7 Ma
CODY enables quantitatively spatiotemporal predictions on in vivo gut microbial variability induced by diet intervention
Microbial variations in the human gut are harbored in temporal and spatial heterogeneity, and quantitative prediction of spatiotemporal dynamic changes in the gut microbiota is imperative for development of tailored microbiome-directed therapeutics treatments, e.g. precision nutrition. Given the high-degree complexity of microbial variations, subject to the dynamic interactions among host, microbial, and environmental factors, identifying how microbiota colonize in the gut represents an important challenge. Here we present COmputing the DYnamics of microbiota (CODY), a multiscale framework that integrates species-level modeling of microbial dynamics and ecosystem-level interactions into a mathematical model that characterizes spatial-specific in vivo microbial residence in the colon as impacted by host physiology. The framework quantifies spatiotemporal resolution of microbial variations on species-level abundance profiles across site-specific colon regions and in feces, independent of a priori knowledge. We demonstrated the effectiveness of CODY using cross-sectional data from two longitudinal metagenomics studies—the microbiota development during early infancy and during short-term diet intervention of obese adults. For each cohort, CODY correctly predicts the microbial variations in response to diet intervention, as validated by available metagenomics and metabolomics data. Model simulations provide insight into the biogeographical heterogeneity among lumen, mucus, and feces, which provides insight into how host physical forces and spatial structure are shaping microbial structure and functionality
Mixing in chaotic flows with swimming bacteria
This is a manuscript accepted for publication on Physical Review Fluids,
Gallery of Fluid Motion special issue. The manuscript is associated with a
poster winner of the 39th Annual Gallery of Fluid Motion Award, for work
presented at the 74th Annual Meeting of the American Physical Society's
Division of Fluid Dynamics (Phoenix, AZ, USA 2021).Comment: This is a manuscript accepted for publication on Physical Review
Fluids, Gallery of Fluid Motion special issu
Solving the Discretised Multiphase Flow Equations with Interface Capturing on Structured Grids Using Machine Learning Libraries
This paper solves the discretised multiphase flow equations using tools and
methods from machine-learning libraries. The idea comes from the observation
that convolutional layers can be used to express a discretisation as a neural
network whose weights are determined by the numerical method, rather than by
training, and hence, we refer to this approach as Neural Networks for PDEs
(NN4PDEs). To solve the discretised multiphase flow equations, a multigrid
solver is implemented through a convolutional neural network with a U-Net
architecture. Immiscible two-phase flow is modelled by the 3D incompressible
Navier-Stokes equations with surface tension and advection of a volume fraction
field, which describes the interface between the fluids. A new compressive
algebraic volume-of-fluids method is introduced, based on a residual
formulation using Petrov-Galerkin for accuracy and designed with NN4PDEs in
mind. High-order finite-element based schemes are chosen to model a collapsing
water column and a rising bubble. Results compare well with experimental data
and other numerical results from the literature, demonstrating that, for the
first time, finite element discretisations of multiphase flows can be solved
using an approach based on (untrained) convolutional neural networks. A benefit
of expressing numerical discretisations as neural networks is that the code can
run, without modification, on CPUs, GPUs or the latest accelerators designed
especially to run AI codes.Comment: 34 pages, 18 figures, 4 table
A Forward Reachability Perspective on Robust Control Invariance and Discount Factors in Reachability Analysis
Control invariant sets are crucial for various methods that aim to design
safe control policies for systems whose state constraints must be satisfied
over an indefinite time horizon. In this article, we explore the connections
among reachability, control invariance, and Control Barrier Functions (CBFs) by
examining the forward reachability problem associated with control invariant
sets. We present the notion of an "inevitable Forward Reachable Tube" (FRT) as
a tool for analyzing control invariant sets. Our findings show that the
inevitable FRT of a robust control invariant set with a differentiable boundary
is the set itself. We highlight the role of the differentiability of the
boundary in shaping the FRTs of the sets through numerical examples. We also
formulate a zero-sum differential game between the control and disturbance,
where the inevitable FRT is characterized by the zero-superlevel set of the
value function. By incorporating a discount factor in the cost function of the
game, the barrier constraint of the CBF naturally arises as the constraint that
is imposed on the optimal control policy. As a result, the value function of
our FRT formulation serves as a CBF-like function, which has not been
previously realized in reachability studies. Conversely, any valid CBF is also
a forward reachability value function inside the control invariant set, thereby
revealing the inverse optimality of the CBF. As such, our work establishes a
strong link between reachability, control invariance, and CBFs, filling a gap
that prior formulations based on backward reachability were unable to bridge.Comment: The first two authors contributed equally to this wor
The Grizzly, November 3, 2016
Search for New VPAA / Dean Comes to an End • Alumni to Speak on AAAS Education Panel • Suspense Thriller Takes UC Stage • International Perspective: Chinese Student Takes on U.S. Public Transportation • Sustainable Students Create Change in Wismer • Homecoming King and Queen Reflect on Time at UC • Opinions: Drake\u27s Diss Track About Kid Cudi Crossed the Line; Tradition of Homecoming Court Needs to Go • Splash! Bears Back in Action! • UC Athlete Making a Difference Off the Fieldhttps://digitalcommons.ursinus.edu/grizzlynews/1654/thumbnail.jp
Genome-Wide Association Study of Smoking Trajectory and Meta-Analysis of Smoking Status in 842,000 Individuals
Here we report a large genome-wide association study (GWAS) for longitudinal smoking phenotypes in 286,118 individuals from the Million Veteran Program (MVP) where we identified 18 loci for smoking trajectory of current versus never in European Americans, one locus in African Americans, and one in Hispanic Americans. Functional annotations prioritized several dozen genes where significant loci co-localized with either expression quantitative trait loci or chromatin interactions. The smoking trajectories were genetically correlated with 209 complex traits, for 33 of which smoking was either a causal or a consequential factor. We also performed European-ancestry meta-analyses for smoking status in the MVP and GWAS & Sequencing Consortium of Alcohol and Nicotine use (GSCAN) (Ntotal = 842,717) and identified 99 loci for smoking initiation and 13 loci for smoking cessation. Overall, this large GWAS of longitudinal smoking phenotype in multiple populations, combined with a meta-GWAS for smoking status, adds new insights into the genetic vulnerability for smoking behavior
Cardiac magnetic resonance T1 and extracellular volume mapping with motion correction and co-registration based on fast elastic image registration
10.1007/s10334-017-0668-2Magnetic Resonance Materials in Physics, Biology and Medicine311115-12
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