1,384 research outputs found
Analog quantum chemistry simulation
Quantum computers hold the promise to provide outstanding computational speed
ups in chemical problems, like the determination of the electronic ground state
energy of molecules. Here, we demonstrate that the same goal can be achieved
with an analog quantum simulator which combines two well-established
technologies, namely, ultra-cold atoms in optical lattices and cavity QED. In
the proposed simulator, fermionic atoms hopping in an optical potential play
the role of electrons, additional optical potentials provide the nuclear
attraction, while a single spin excitation over a Mott insulator mediates the
electronic Coulomb repulsion. We analyze the impact of discretization and
finite size effects of the lattice, and provide the working conditions required
for the precise determination of the electronic energy of simple molecules.Comment: 12 pages, 5 figure
Atlas Toolkit: Fast registration of 3D morphological datasets in the absence of landmarks
Image registration is a gateway technology for Developmental Systems Biology, enabling computational analysis of related datasets within a shared coordinate system. Many registration tools rely on landmarks to ensure that datasets are correctly aligned; yet suitable landmarks are not present in many datasets. Atlas Toolkit is a Fiji/ImageJ plugin collection offering elastic group-wise registration of 3D morphological datasets, guided by segmentation of the interesting morphology. We demonstrate the method by combinatorial mapping of cell signalling events in the developing eyes of chick embryos, and use the integrated datasets to predictively enumerate Gene Regulatory Network states
CaDIS: Cataract dataset for surgical RGB-image segmentation
Video feedback provides a wealth of information about surgical procedures and is the main sensory cue for surgeons. Scene understanding is crucial to computer assisted interventions (CAI) and to post-operative analysis of the surgical procedure. A fundamental building block of such capabilities is the identification and localization of surgical instruments and anatomical structures through semantic segmentation. Deep learning has advanced semantic segmentation techniques in the recent years but is inherently reliant on the availability of labelled datasets for model training. This paper introduces a dataset for semantic segmentation of cataract surgery videos complementing the publicly available CATARACTS challenge dataset. In addition, we benchmark the performance of several state-of-the-art deep learning models for semantic segmentation on the presented dataset. The dataset is publicly available at https://cataracts-semantic-segmentation2020.grand-challenge.org/
The Freundlich model of adsorption for calculation of specific surface areaS
The specific surface area of solids and the surface area occupied by the active phase (metal or oxide) on a support are parameters of the utmost importance in adsorption and catalysis. For the determination of the former, the BET equation is universally established. For the evaluation of the latter the works of selective chemisorption, initiated by Emmett and Brunauer (I ), for metals and by Bridges et al. (2) and Weller et al. (3), for oxides have come to represent important contributions. Some of the classical models of adsorption have also been used for evaluation of specific surfaces (Langmuir equation) (4) and the dispersion of supported metals or oxides (Freundlich equation) (5). Both of them are applicable to physisorption as well as chemisorption processes
Selective Harmonic Mitigation Technique for Cascaded H-Bridge Converters With Nonequal DC Link Voltages
Multilevel converters have received increased interest
recently as a result of their ability to generate high quality
output waveforms with a low switching frequency. This makes
them very attractive for high power applications. A Cascaded HBridge
converter is a multilevel topology which is formed from
the series connection of H-Bridge cells. Optimized pulse width
modulation techniques such as Selective Harmonic Elimination
(SHE-PWM) or Selective Harmonic Mitigation (SHM-PWM) are
capable of pre-programming the harmonic profile of the output
waveform over a range of modulation indices. Such modulation
methods may however not perform optimally if the DC links of
the Cascaded H-Bridge Converter are not balanced. This paper
presents a new SHM-PWM control strategy which is capable of
meeting grid codes even under non-equal DC link voltages. The
method is based on the interpolation of different sets of angles
obtained for specific situations of imbalance. Both simulation
and experimental results are presented to validate the proposed
control method
Developing Dementia-Friendly Tourism Destinations: An Exploratory Analysis
Dementia is emerging as a global issue. Increases in life expectancy create an older population structure with accompanying health needs but also high lifestyle expectations. For example existing generations have come to expect to be able to participate in leisure and tourism activities in later life, which can be constrained by the onset of dementia. Leading healthy lifestyles and engaging in tourism activities are viewed as fundamental to remaining active and contributing to slowing the progress of dementia. This study is the first to examine the challenges and implications of the growing scale of dementia and the business opportunities this may create for destinations wishing to achieve dementia-friendly status. The paper reports results from an initial scoping study with tourism businesses in a coastal resort in the United Kingdom with such ambitions to assess the nature of the issues that arose from a series of face-to-face interviews
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