3,634 research outputs found
Geometric inequalities from phase space translations
We establish a quantum version of the classical isoperimetric inequality
relating the Fisher information and the entropy power of a quantum state. The
key tool is a Fisher information inequality for a state which results from a
certain convolution operation: the latter maps a classical probability
distribution on phase space and a quantum state to a quantum state. We show
that this inequality also gives rise to several related inequalities whose
counterparts are well-known in the classical setting: in particular, it implies
an entropy power inequality for the mentioned convolution operation as well as
the isoperimetric inequality, and establishes concavity of the entropy power
along trajectories of the quantum heat diffusion semigroup. As an application,
we derive a Log-Sobolev inequality for the quantum Ornstein-Uhlenbeck
semigroup, and argue that it implies fast convergence towards the fixed point
for a large class of initial states.Comment: 37 pages; updated to match published versio
SDDPM: Speckle Denoising Diffusion Probabilistic Models
Coherent imaging systems, such as medical ultrasound and synthetic aperture
radar (SAR), are subject to corruption from speckle due to sub-resolution
scatterers. Since speckle is multiplicative in nature, the constituent image
regions become corrupted to different extents. The task of denoising such
images requires algorithms specifically designed for removing signal-dependent
noise. This paper proposes a novel image denoising algorithm for removing
signal-dependent multiplicative noise with diffusion models, called Speckle
Denoising Diffusion Probabilistic Models (SDDPM). We derive the mathematical
formulations for the forward process, the reverse process, and the training
objective. In the forward process, we apply multiplicative noise to a given
image and prove that the forward process is Gaussian. We show that the reverse
process is also Gaussian and the final training objective can be expressed as
the Kullback Leibler (KL) divergence between the forward and reverse processes.
As derived in the paper, the final denoising task is a single step process,
thereby reducing the denoising time significantly. We have trained our model
with natural land-use images and ultrasound images for different noise levels.
Extensive experiments centered around two different applications show that
SDDPM is robust and performs significantly better than the comparative models
even when the images are severely corrupted.Comment: 12 pages, 12 figure
Progress in Element Analysis on a High-Voltage Electron Microscope
X-Ray microprobe (XMA) and electron energy-loss (EELS) spectrometers have been installed on the high-voltage electron microscope (HVEM). The probe size has been measured and background reduction is in progress for XMA and EELS as are improvements in electron optics for EELS and sensitivity measurements.
XMA is currently useful for qualitative analysis and has been used by several investigators from our laboratory and outside laboratories. However, EELS background levels are still too high for meaningful results to be obtained. Standards suitable for biological specimens are being measured, and a library for quantitative analysis is being compiled
Pressure effects on charge, spin, and metal-insulator transitions in narrow bandwidth manganite PrCaMnO
Pressure effects on the charge and spin states and the relation between the
ferromagnetic and metallic states were explored on the small bandwidth
manganite PrCaMnO (x = 0.25, 0.3, 0.35). Under pressure,
the charge ordering state is suppressed and a ferromagnetic metallic state is
induced in all three samples. The metal-insulator transition temperature
(T) increases with pressure below a critical point P*, above which
T decreases and the material becomes insulating as at the ambient
pressure. The e electron bandwidth and/or band-filling mediate the
pressure effects on the metal-insulator transition and the magnetic transition.
In the small bandwidth and low doping concentration compound (x = 0.25), the
T and Curie temperature (T) change with pressure in a reverse way
and do not couple under pressure. In the x = 0.3 compound, the relation of
T and T shows a critical behavior: They are coupled in the range
of 0.8-5 GPa and decoupled outside of this range. In the x = 0.35
compound, T and T are coupled in the measured pressure range where
a ferromagnetic state is present
Family visits to libraries and bookshops: observations and implications for digital libraries
This paper explores how families select books for leisure reading. We recruited 17 families (adults and children) for this study, and spent time with each in both bookshops and public libraries. Our research aims to add to understanding of how families interact with books and bookshelves in these places, and how digital libraries might best support the shared needs of these inter-generational users. Much of our understanding of how an eBook should look and feel comes from generalizations about books and assumptions about the needs of those individuals who read them. We explore how children and adults search and browse for books together, with specific focus on the type of information seeking tasks that families undertake and on the families’ shared search and browsing strategies. We further explore the implications of this study for the development of digital libraries for children and families
Measurement and Modeling of Infrared Nonlinear Absorption Coefficients and Laser-induced Damage Thresholds in Ge and GaSb
Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al2O3 anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond pulses, respectively
Temperature dependent optical studies of TiCoO
We present the results of Raman and photoluminescence (PL) studies on
epitaxial anatase phase TiCoO films for = 0-0.07, grown by
pulsed laser deposition. The low doped system (=0.01 and 0.02) shows a Curie
temperature of ~700 K in the as-grown state. The Raman spectra from the doped
and undoped films confirm their anatase phase. The photoluminescence spectrum
is characterized by a broad emission from self-trapped excitons (STE) at 2.3 eV
at temperatures below 120 K. This peak is characteristic of the anatase-phase
TiO and shows a small blueshift with increasing doping concentration. In
addition to the emission from STE, the Co-doped samples show two emission lines
at 2.77 eV and 2.94 eV that are absent in the undoped film indicative of a
spin-flip energy.Comment: 8 pages, 4 figure
A systematic and prospectively validated approach for identifying synergistic drug combinations against malaria.
BACKGROUND: Nearly half of the world's population (3.2 billion people) were at risk of malaria in 2015, and resistance to current therapies is a major concern. While the standard of care includes drug combinations, there is a pressing need to identify new combinations that can bypass current resistance mechanisms. In the work presented here, a combined transcriptional drug repositioning/discovery and machine learning approach is proposed. METHODS: The integrated approach utilizes gene expression data from patient-derived samples, in combination with large-scale anti-malarial combination screening data, to predict synergistic compound combinations for three Plasmodium falciparum strains (3D7, DD2 and HB3). Both single compounds and combinations predicted to be active were prospectively tested in experiment. RESULTS: One of the predicted single agents, apicidin, was active with the AC50 values of 74.9, 84.1 and 74.9 nM in 3D7, DD2 and HB3 P. falciparum strains while its maximal safe plasma concentration in human is 547.6 ± 136.6 nM. Apicidin at the safe dose of 500 nM kills on average 97% of the parasite. The synergy prediction algorithm exhibited overall precision and recall of 83.5 and 65.1% for mild-to-strong, 48.8 and 75.5% for moderate-to-strong and 12.0 and 62.7% for strong synergies. Some of the prospectively predicted combinations, such as tacrolimus-hydroxyzine and raloxifene-thioridazine, exhibited significant synergy across the three P. falciparum strains included in the study. CONCLUSIONS: Systematic approaches can play an important role in accelerating discovering novel combinational therapies for malaria as it enables selecting novel synergistic compound pairs in a more informed and cost-effective manner
BUSINESS PROCESS REDESIGN AND INFORMATION ARCHITECTURE: ESTABLISHING THE MISSING LINKS
Business Process Redesign (BPR) and Information Architecture (IA) have been recognized as high organizational priority agenda items in the 1990s. This paper provides tile premise for integrating these two critical issues. A model depicting the relationship between IA and BPR is presented. IA design and BPR share a common focus on business processes and, when properly conducted, IA design should produce a stable information architecture capable of supporting existing as well as improved business processes. Furthermore, selected IA methods and techniques are recommended for possible application in BPR. Future research is suggested concerning the need to validate this BPR and IA relationship and test the appropriateness of applying IA methodologies to BPR
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