11,889 research outputs found
Dynamic message-passing equations for models with unidirectional dynamics
Understanding and quantifying the dynamics of disordered out-of-equilibrium
models is an important problem in many branches of science. Using the dynamic
cavity method on time trajectories, we construct a general procedure for
deriving the dynamic message-passing equations for a large class of models with
unidirectional dynamics, which includes the zero-temperature random field Ising
model, the susceptible-infected-recovered model, and rumor spreading models. We
show that unidirectionality of the dynamics is the key ingredient that makes
the problem solvable. These equations are applicable to single instances of the
corresponding problems with arbitrary initial conditions, and are
asymptotically exact for problems defined on locally tree-like graphs. When
applied to real-world networks, they generically provide a good analytic
approximation of the real dynamics.Comment: Final versio
The curious morphology and orientation of Orion proplyd HST-10
HST-10 is one of the largest proplyds in the Orion Nebula and is located
approximately 1' SE of the Trapezium. Unlike other proplyds in Orion, however,
the long-axis of HST-10 does not align with theta 1 C Ori, but is instead
aligned with the rotational axis of the HST-10 disk. This cannot be easily
explained using current photo-evaporation models. In this letter, we present
high spatial resolution near-infrared images of the Orion proplyd HST-10 using
Keck/NIRC2 with the Laser Guide Star Adaptive Optics system, along with
multi-epoch analysis of HH objects near HST-10 using Hubble Space Telescope
WFPC2 and ACS cameras. Our narrow-band near-IR images resolve the proplyd
ionization front (IF) and circumstellar disk down to 23 AU at the distance to
Orion in Br gamma, He I, H_2, and PAH emission. Br gamma and He I emission
primarily trace the IF (with the disk showing prominently in silhouette), while
the H_2 and PAH emission trace the surface of the disk itself. PAH emission
also traces small dust grains within the proplyd envelope which is asymmetric
and does not coincide with the IF. The curious morphology of the PAH emission
may be due to UV-heating by both theta 1C Ori and theta 2A Ori. Multi-epoch HST
images of the HST-10 field show proper motion of 3 knots associated with HH
517, clearly indicating that HST-10 has a jet. We postulate that the
orientation of HST-10 is determined by the combined ram-pressure of this jet
and the FUV-powered photo-ablation flow from the disk surface.Comment: 12 pages, 2 figures. Accepted for publication in ApJ Letters, 4 Nov
201
Review of test methods used for the measurement of hermeticity in packages containing small cavities
Online Learning of Power Transmission Dynamics
We consider the problem of reconstructing the dynamic state matrix of
transmission power grids from time-stamped PMU measurements in the regime of
ambient fluctuations. Using a maximum likelihood based approach, we construct a
family of convex estimators that adapt to the structure of the problem
depending on the available prior information. The proposed method is fully
data-driven and does not assume any knowledge of system parameters. It can be
implemented in near real-time and requires a small amount of data. Our learning
algorithms can be used for model validation and calibration, and can also be
applied to related problems of system stability, detection of forced
oscillations, generation re-dispatch, as well as to the estimation of the
system state.Comment: 7 pages, 4 figure
Rapid changes in shape and number of MHC class II expressing cells in rat airways after Mycoplasma pulmonis infection
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Mycoplasma pulmonis infection in rodents causes a chronic inflammatory airway disease with a strong immunological component, leading to mucosal remodeling and angiogenesis. We sought to determine the effect of this infection on the shape and number of dendritic cells and other major histocompatibility complex (MHC) class II expressing cells in the airway mucosa of Wistar rats. Changes in the shape of subepithelial OX6 (anti-MHC class II)-immunoreactive cells were evident in the tracheal mucosa 2 days after intranasal inoculation with M. pulmonis. By 1 week, the shape of the cells had changed from stellate to rounded (mean shape index increased from 0.42 to 0.77). The number of OX6-positive cells was increased 6-fold at 1 week and 16-fold at 4 weeks. Coincident with these changes, many columnar epithelial cells developed OX6 immunoreactivity, which was still present at 4 weeks. We conclude that M. pulmonis infection creates a potent immunologic stimulus that augments and transforms the OX6-immunoreactive cell population in the airways by changing the functional state of airway dendritic cells, initiating an influx of MHC class II expressing cells, and activating expression of MHC class II molecules by airway epithelial cells
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