79 research outputs found
Eikonal Approximation to 5D Wave Equations as Geodesic Motion in a Curved 4D Spacetime
We first derive the relation between the eikonal approximation to the Maxwell
wave equations in an inhomogeneous anisotropic medium and geodesic motion in a
three dimensional Riemannian manifold using a method which identifies the
symplectic structure of the corresponding mechanics. We then apply an analogous
method to the five dimensional generalization of Maxwell theory required by the
gauge invariance of Stueckelberg's covariant classical and quantum dynamics to
demonstrate, in the eikonal approximation, the existence of geodesic motion for
the flow of mass in a four dimensional pseudo-Riemannian manifold. These
results provide a foundation for the geometrical optics of the five dimensional
radiation theory and establish a model in which there is mass flow along
geodesics. Finally we discuss the case of relativistic quantum theory in an
anisotropic medium as well. In this case the eikonal approximation to the
relativistic quantum mechanical current coincides with the geodesic flow
governed by the pseudo-Riemannian metric obtained from the eikonal
approximation to solutions of the Stueckelberg-Schr\"odinger equation. This
construction provides a model for an underlying quantum mechanical structure
for classical dynamical motion along geodesics on a pseudo-Riemannian manifold.
The locally symplectic structure which emerges is that of Stueckelberg's
covariant mechanics on this manifold.Comment: TeX file. 17 pages. Rewritten for clarit
Spatial distributions of local illumination color in natural scenes
In natural complex environments, the elevation of the sun and the presence of occluding objects and mutual reflections cause variations in the spectral composition of the local illumination across time and location. Unlike the changes in time and their consequences for color appearance and constancy, the spatial variations of local illumination color in natural scenes have received relatively little attention. The aim of the present work was to characterize these spatial variations by spectral imaging. Hyperspectral radiance images were obtained from 30 rural and urban scenes in which neutral probe spheres were embedded. The spectra of the local illumination at 17 sample points on each sphere in each scene were extracted and a total of 1904 chromaticity coordinates and correlated color temperatures (CCTs) derived. Maximum differences in chromaticities over spheres and over scenes were similar. When data were pooled over scenes, CCTs ranged from 3000 K to 20,000 K, a variation of the same order of magnitude as that occurring over the day. Any mechanisms that underlie stable surface color perception in natural scenes need to accommodate these large spatial variations in local illumination color.This work was supported by the Centro de FĂsica of Minho University, Braga, Portugal, by the European Regional Development Fund through Program COMPETE (FCOMP-01-0124-FEDER-009858/029564), by the National Portuguese funds through Fundação para a CiĂȘncia e a Tecnologia, Portugal (Grants PTDC/EEA-EEL/098572/2008 and PTDC/MHC-PCN/4731/2012), and by the Engineering and Physical Sciences Research Council, United Kingdom (Grants GR/R39412/01, EP/B000257/1 and EP/E056512/1). We thank Paulo D. A. Pinto and JoĂŁo M. M. Linhares for collaboration
in the acquisition of hyperspectral data of some scenes and Paulo
D. A. Pinto for the preparation of the gray spheres
Exploring Immune Development in Infants With Moderate to Severe Atopic Dermatitis
Background: Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in infancy with a complex pathology. In adults, the clinical severity of AD has been associated with increases in T helper cell type (Th) 2, Th22, and Th17 serum markers, including high levels of CC chemokine ligand (CCL) 17 and CCL22 chemokines. Objective: To explore the possible association between serum chemokine levels and AD severity in infants with moderate-to-severe AD and elevated immunoglobulin E (IgE). Subjects and methods: Serum samples (nâ=â41) obtained from a randomized, double-blind, and clinical dietary intervention study were used to study biomarkers in infants with AD. Baseline- and post-intervention samples (4âmonths) were used, six chemokines and nine ratios thereof were analyzed using Luminex and correlated to AD severity. In the initial study, the infants were randomized to receive extensively hydrolyzed whey-based formula without (control) or with short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides (9:1) and Bifidobacterium breve M-16V (active). Results: 31 Infants up to 11âmonths of age, with an objective-SCORAD score (oSCORAD)ââ„â20 and elevated total-IgE and/or specific-IgE levels were included. In time, the median oSCORAD decreased in both groups by -8 (control, pâ<â0.05; active, pâ<â0.01). Irrespective of dietary intervention, several changes in Th2 chemokines (CCL17 and CCL22), inflammatory chemokine (CCL20), and the Th1 chemokine, CXC chemokine ligand (CXCL) 9, were detected over time. Overall CCL17 correlated to oSCORAD (râ=â0.446, pâ<â0.01). After 4âmonths of dietary intervention, CXCL9 was higher (pâ<â0.01) in the active group compared with control [active, 2.33 (1.99-2.89); controls, 1.95 (1.77-2.43) log 10 median (range)]. In addition, a reduction in Th2/Th1 chemokine ratios for CCL17/CXCL9, CCL22/CXCL9, CCL20/CXCL10, and CCL20/CXCL11 was detected associated with the active intervention. Conclusion: While this study is small and exploratory in nature, these data contribute to immune biomarker profiling and understanding of AD in infants
Flow cytometry immunophenotyping for diagnostic orientation and classification of pediatric cancer based on the EuroFlow Solid Tumor Orientation Tube (STOT)
Early diagnosis of pediatric cancer is key for adequate patient management and improved outcome. Although multiparameter flow cytometry (MFC) has proven of great utility in the diagnosis and classification of hematologic malignancies, its application to non-hematopoietic pediatric tumors remains limited. Here we designed and prospectively validated a new single eight-color antibody combination-solid tumor orientation tube, STOT-for diagnostic screening of pediatric cancer by MFC. A total of 476 samples (139 tumor mass, 138 bone marrow, 86 lymph node, 58 peripheral blood, and 55 other body fluid samples) from 296 patients with diagnostic suspicion of pediatric cancer were analyzed by MFC vs. conventional diagnostic procedures. STOT was designed after several design-test-evaluate-redesign cycles based on a large panel of monoclonal antibody combinations tested on 301 samples. In its final version, STOT consists of a single 8-color/12-marker antibody combination (CD99-CD8/(nu)myogenin/CD4-EpCAM/CD56/GD2/(sm)CD3-CD19/(cy)CD3-CD271/CD45). Prospective validation of STOT in 149 samples showed concordant results with the patient WHO/ICCC-3 diagnosis in 138/149 cases (92.6%). These included: 63/63 (100%) reactive/disease-free samples, 43/44 (98%) malignant and 4/4 (100%) benign non-hematopoietic tumors together with 28/38 (74%) leukemia/lymphoma cases; the only exception was Hodgkin lymphoma that required additional markers to be stained.& nbsp;In addition, STOT allowed accurate discrimination among the four most common subtypes of malignant CD45(-) CD56(++) non-hematopoietic solid tumors: 13/13 (GD2(++) (nu)myogenin(-) CD271(-/+) (nu)MyoD1(-) CD99(-) EpCAM(-)) neuroblastoma samples, 5/5 (GD2(-) (nu)myogenin(++) CD271(++) (nu)MyoD1(++) CD99(-/+) EpCAM(-)) rhabdomyosarcomas, 2/2 (GD2(-/+) (nu)myogenin(-) CD271(+) (nu)MyoD1(-) CD99(+) EpCAM(-)) Ewing sarcoma family of tumors, and 7/7 (GD2(-) (nu)myogenin(-) CD271(+) (nu)MyoD1(-) CD99(-) EpCAM(+)) Wilms tumors. In summary, here we designed and validated a new standardized antibody combination and MFC assay for diagnostic screening of pediatric solid tumors that might contribute to fast and accurate diagnostic orientation and classification of pediatric cancer in routine clinical practice.Stemcel biology/Regenerative medicine (incl. bloodtransfusion
Highly-parallelized simulation of a pixelated LArTPC on a GPU
The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype
Changes in the economic aspects of farming with data for farm business analysis
SIGLELD:7644.371(1981/82) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Report on farming in the Eastern Counties of England 1987/88 Changes in the economic aspects of farming with data for farm business analysis
9.00; incorporating Farm Planning Data 1987/1988SIGLEAvailable from British Library Document Supply Centre- DSC:7644.371(1987/88) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
SOME UNRESOLVED ISSUES OF CONTROL IN CONSUMER TESTS: THE EFFECTS OF EXPECTED MONETARY REWARD AND HUNGER
Prestatieverbetering over langere tijd: Het effect van lean op doorlooptijden op het LMMI , St. Elisabeth-Tweesteden Ziekenhuis
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