2,043 research outputs found
A Dodecalogue of Basic Didactics from Applications of Abstract Differential Geometry to Quantum Gravity
We summarize the twelve most important in our view novel concepts that have
arisen, based on results that have been obtained, from various applications of
Abstract Differential Geometry (ADG) to Quantum Gravity (QG). The present
document may be used as a concise, yet informal, discursive and peripatetic
conceptual guide-cum-terminological glossary to the voluminous technical
research literature on the subject. In a bonus section at the end, we dwell on
the significance of introducing new conceptual terminology in future QG
research by means of `poetic language'Comment: 16 pages, preliminary versio
3D Printing Provides a Precise Approach in the Treatment of Tetralogy of Fallot, Pulmonary Atresia with Major Aortopulmonary Collateral Arteries.
Patients with tetralogy of Fallot, pulmonary atresia, and multiple aortopulmonary collateral arteries (Tet PA MAPCAs) have a wide spectrum of anatomy and disease severity. Management of these patients can be challenging and often require multiple high-risk surgical and interventional catheterization procedures. These interventions are made challenging by complex anatomy that require the proceduralist to mentally reconstruct three-dimensional anatomic relationships from two-dimensional images. Three-dimensional (3D) printing is an emerging medical technology that provides added benefits in the management of patients with Tet PA MAPCAs. When used in combination with current diagnostic modalities and procedures, 3D printing provides a precise approach to the management of these challenging, high-risk patients. Specifically, 3D printing enables detailed surgical and interventional planning prior to the procedure, which may improve procedural outcomes, decrease complications, and reduce procedure-related radiation dose and contrast load
An Evaluated Certification Services System for the German National Root CA - Legally Binding and Trustworthy Transactions in E-Business and E-Government
National Root CAs enable legally binding E-Business and E-Government
transactions. This is a report about the development, the evaluation and the
certification of the new certification services system for the German National
Root CA. We illustrate why a new certification services system was necessary,
and which requirements to the new system existed. Then we derive the tasks to
be done from the mentioned requirements. After that we introduce the initial
situation at the beginning of the project. We report about the very process and
talk about some unfamiliar situations, special approaches and remarkable
experiences. Finally we present the ready IT system and its impact to
E-Business and E-Government.Comment: 6 pages; 1 figure; IEEE style; final versio
Loop quantum black hole
In this paper we consider the Kantowski-Sachs space-time in Ashtekar
variables and the quantization of this space-time starting from the complete
loop quantum gravity theory. The Kanthowski-Sachs space-time coincides with the
Schwarzschild black hole solution inside the horizon. By studying this model we
can obtain information about the black hole singularity and about the dynamics
across the point r=0. We studied this space-time in ADM variables in two
previous papers where we showed that the classical black hole singularity
disappears in quantum theory. In this work we study the same model in Ashtekar
variables and we obtain a regular space-time inside the horizon region and that
the dynamics can be extend further the classical singularity.Comment: 12 pages, latex. We introduce and we calculate the spectrum of the
operator 1/|E
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Assessment of surface solar irradiance derived from real-time modelling techniques and verification with ground-based measurements
This study focuses on the assessment of surface solar radiation (SSR) based on operational neural network (NN) and multi-regression function (MRF) modelling techniques that produce instantaneous (in less than 1 min) outputs. Using real-time cloud and aerosol optical properties inputs from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat Second Generation (MSG) satellite and the Copernicus Atmosphere Monitoring Service (CAMS), respectively, these models are capable of calculating SSR in high resolution (1 nm, 0.05 degree, 15 min) that can be used for spectrally integrated irradiance maps, databases and various applications related to energy exploitation. The real-time models are validated against ground-based measurements of the Baseline Surface Radiation Network (BSRN) in a temporal range varying from 15 min to monthly means, while a sensitivity analysis of the cloud and aerosol effects on SSR is performed to ensure reliability under different sky and climatological conditions. The simulated outputs, compared to their common training dataset created by the radiative transfer model (RTM) libRadtran, showed median error values in the range −15 to +15 % for the NN that produces spectral irradiances (NNS), 5–6 % underestimation for the integrated NN and close to zero errors for the MRF technique. The verification against BSRN revealed that the real-time calculation uncertainty ranges from −100 to +40 and −20 to +20 W/m^2, for the 15 min and monthly mean global horizontal irradiance (GHI) averages, respectively, while the accuracy of the input parameters, in terms of aerosol and cloud optical thickness (AOD and COT), and their impact on GHI, was of the order of 10 % as compared to the ground-based measurements. The proposed system aims to be utilized through studies and real-time applications which are related to solar energy production planning and use
Algebraic description of spacetime foam
A mathematical formalism for treating spacetime topology as a quantum
observable is provided. We describe spacetime foam entirely in algebraic terms.
To implement the correspondence principle we express the classical spacetime
manifold of general relativity and the commutative coordinates of its events by
means of appropriate limit constructions.Comment: 34 pages, LaTeX2e, the section concerning classical spacetimes in the
limit essentially correcte
Millimeter Wave Scattering from Neutral and Charged Water Droplets
We investigated 94GHz millimeter wave (MMW) scattering from neutral and
charged water mist produced in the laboratory with an ultrasonic atomizer.
Diffusion charging of the mist was accomplished with a negative ion generator
(NIG). We observed increased forward and backscattering of MMW from charged
mist, as compared to MMW scattering from an uncharged mist. In order to
interpret the experimental results, we developed a model based on classical
electrodynamics theory of scattering from a dielectric sphere with
diffusion-deposited mobile surface charge. In this approach, scattering and
extinction cross-sections are calculated for a charged Rayleigh particle with
effective dielectric constant consisting of the volume dielectric function of
the neutral sphere and surface dielectric function due to the oscillation of
the surface charge in the presence of applied electric field. For small
droplets with (radius smaller than 100nm), this model predicts increased MMW
scattering from charged mist, which is qualitatively consistent with the
experimental observations. The objective of this work is to develop indirect
remote sensing of radioactive gases via their charging action on atmospheric
humid air.Comment: 18 pages, 8 figure
Gut dysfunction in patients with multiple sclerosis and the role of spinal cord involvement in the disease.
Bowel and bladder symptoms are highly prevalent in patients with multiple sclerosis (MS). Bladder dysfunction (affecting 75% of these patients) is caused by disease in the spinal cord, whilst the pathophysiology of bowel dysfunction is unknown. Pathways regulating both the organs lie in close proximity to the spinal cord, and coexistence of their dysfunction might be the result of a common pathophysiology. If so, the prevalence of bladder symptoms should be greater in patients with MS and bowel symptoms. This hypothesis is tested in the study. We also evaluated how patient-reported symptoms quantify bowel dysfunction
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