102 research outputs found
Learning Discrete Weights and Activations Using the Local Reparameterization Trick
In computer vision and machine learning, a crucial challenge is to lower the
computation and memory demands for neural network inference. A commonplace
solution to address this challenge is through the use of binarization. By
binarizing the network weights and activations, one can significantly reduce
computational complexity by substituting the computationally expensive floating
operations with faster bitwise operations. This leads to a more efficient
neural network inference that can be deployed on low-resource devices. In this
work, we extend previous approaches that trained networks with discrete weights
using the local reparameterization trick to also allow for discrete
activations. The original approach optimized a distribution over the discrete
weights and uses the central limit theorem to approximate the pre-activation
with a continuous Gaussian distribution. Here we show that the probabilistic
modeling can also allow effective training of networks with discrete activation
as well. This further reduces runtime and memory footprint at inference time
with state-of-the-art results for networks with binary activations
Raman Spectra of Titanium Carbide MXene from Machine-Learning Force Field Molecular Dynamics
MXenes represent one of the largest class of 2D materials with promising
applications in many fields and their properties tunable by the surface group
composition. Raman spectroscopy is expected to yield rich information about the
surface composition, but the interpretation of measured spectra has proven
challenging. The interpretation is usually done via comparison to simulated
spectra, but there are large discrepancies between the experimental and earlier
simulated spectra. In this work, we develop a computational approach to
simulate Raman spectra of complex materials that combines machine-learning
force-field molecular dynamics and reconstruction of Raman tensors via
projection to pristine system modes. The approach can account for the effects
of finite temperature, mixed surfaces, and disorder. We apply our approach to
simulate Raman spectra of titanium carbide MXene and show that all these
effects must be included in order to properly reproduce the experimental
spectra, in particular the broad features. We discuss the origin of the peaks
and how they evolve with surface composition, which can then be used to
interpret experimental results
Shrinking the Quadratic Estimator
We study a regression characterization for the quadratic estimator of weak
lensing, developed by Hu and Okamoto (2001,2002), for cosmic microwave
background observations. This characterization motivates a modification of the
quadratic estimator by an adaptive Wiener filter which uses the robust Bayesian
techniques described in Strawderman (1971) and Berger (1980). This technique
requires the user to propose a fiducial model for the spectral density of the
unknown lensing potential but the resulting estimator is developed to be robust
to misspecification of this model. The role of the fiducial spectral density is
to give the estimator superior statistical performance in a "neighborhood of
the fiducial model" while controlling the statistical errors when the fiducial
spectral density is drastically wrong. Our estimate also highlights some
advantages provided by a Bayesian analysis of the quadratic estimator
On digital bioprocessing for manufacturing intelligence: Application of process analytical technology (PAT) and process data analytics (PDA) for upstream process development and intensification
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Controlled defect production in monolayer MoS2 via electron irradiation at ultralow accelerating voltages
Control on spatial location and density of defects in 2D materials can be
achieved using electron beam irradiation. Conversely, ultralow accelerating
voltages (less than or equal to 5kV) are used to measure surface morphology,
with no expected defect creation. We find clear signatures of defect creation
in monolayer (ML) MoS2 at these voltages. Evolution of E' and A1' Raman modes
with electron dose, and appearance of defect activated peaks indicate defect
formation. To simulate Raman spectra of MoS2 at realistic defect distributions,
while retaining density-functional theory accuracy, we combine machine-learning
force fields for phonons and eigenmode projection approach for Raman tensors.
Simulated spectra agree with experiments, with sulphur vacancies as suggested
defects. We decouple defects, doping and carbonaceous contamination using
control (hBN covered and encapsulated MoS2) samples. We observe cryogenic PL
quenching and defect peaks, and find that carbonaceous contamination does not
affect defect creation. These studies have applications in photonics and
quantum emitters.Comment: 35 pages, 19 figures, 4 table
Cataclysmic Variables from SDSS II. The Second Year
The first full year of operation following the commissioning year of the
Sloan Digital Sky Survey has revealed a wide variety of newly discovered
cataclysmic variables. We show the SDSS spectra of forty-two cataclysmic
variables observed in 2002, of which thirty-five are new classifications, four
are known dwarf novae (CT Hya, RZ Leo, T Leo and BZ UMa), one is a known CV
identified from a previous quasar survey (Aqr1) and two are known ROSAT or
FIRST discovered CVs (RX J09445+0357, FIRST J102347.6+003841). The SDSS
positions, colors and spectra of all forty-two systems are presented. In
addition, the results of follow-up studies of several of these objects identify
the orbital periods, velocity curves and polarization that provide the system
geometry and accretion properties. While most of the SDSS discovered systems
are faint (>18th mag) with low accretion rates (as implied from their spectral
characteristics), there are also a few bright objects which may have escaped
previous surveys due to changes in the mass transfer rate.Comment: Accepted for publication in The Astronomical Journal, Vol. 126, Sep.
2003, 44 pages, 25 figures (now with adjacent captions), AASTeX v5.
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Implementation of Clinical Practice Guidelines for Hospitalized Patients With COVID-19 in Academic Medical Centers
This survey study assesses the rate at which US academic medical centers have adopted evidenced-based guidelines for the management of COVID-19 into practice
A Mixed Blessing: Market-Mediated Religious Authority in Neopaganism
This research explores how marketplace dynamics affect religious authority in the context of Neopagan religion. Drawing on an interpretivist study of Wiccan practitioners in Italy, we reveal that engagement with the market may cause considerable, ongoing tensions, based on the inherent contradictions that are perceived to exist between spirituality and commercial gain. As a result, market success is a mixed blessing that can increase religious authority and influence, but is just as likely to decrease authority and credibility. Using an extended case study method, we propose a theoretical framework that depicts the links between our informants’ situated experiences and the macro-level factors affecting religious authority as it interacts with market-mediated dynamics at the global level. Overall, our study extends previous work in macromarketing that has looked at religious authority in the marketplace) and how the processes of globalization are affecting religion
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