gebhart/patrepeval huggingface dataset:
The mechanism of the long spark formation (1979)

The aim of this paper is to present the state of the art of the research on the physics of long sparks. The reference configuration is a non uniform long gap subjected to positive impulse voltages, which is the laboratory schematization of the most critical conditions occurring in the design of EHV apparatus. Under these conditions, the spark formation develops through different subsequent phases : the inception of the first ionization phenomena, the development of corona streamers, the formation of the corona stem and of the leader channel, the leader propagation, the time-evolution of the leader characteristics, the appearance of channel reilluminations, the final jump and the transition to the highly conductive spark channel. Each phase is governed by a complex interaction of electromagnetic, hydrodynamic and thermodynamic elementary processes. Each chapter of the paper presents both the experimental results and the theoretical models which have been obtained for each single phase. In recent years a number of sophisticated measuring systems have been used to study the local conditions of the different discharge phases (space charge distribution, electric field, electron energy, gas temperature and density, etc...) : the first part of each chapter presents a summary of these experimental results, in order to define the physical conditions under which the discharge develops, and to select the elementary phenomena which appear to be dominant. The second part of each chapter presents the different theoretical models, which have been obtained by simplifying the basic electromagnetic, hydrodynamic and thermodynamic equations, according to the dominant phenomena. The good agreement between computed and experimental results, over a large variety of test conditions, certify the large steps forward, which have been taken in the last years by the research on the physics of long sparks. The final objective, i.e. the formulation of a complete breakdown model, able to predict the discharge features in all the possible practical configurations, starting from the physics of the elementary phenomena, is not yet realized, but it appears as a realistic possibility of the further development of the research in this area.
Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials (2014)

The toroidal dipole is a peculiar electromagnetic excitation that can not be presented in terms of standard electric and magnetic multipoles. A static toroidal dipole has been shown to lead to violation of parity in atomic spectra and many other unusual electromagnetic phenomena. The existence of electromagnetic resonances of toroidal nature was experimentally demonstrated only recently, first in the microwave metamaterials, and then at optical frequencies, where they could be important in spectroscopy analysis of a wide class of media with constituents of toroidal symmetry, such as complex organic molecules, fullerenes, bacteriophages, etc. Despite the experimental progress in studying toroidal resonances, no direct link has yet been established between microscopic toroidal excitations and macroscopic scattering characteristics of the medium. To address this essential gap in the electromagnetic theory, we have developed an analytical approach for calculating the transmissivity and reflectivity of thin slabs of materials that exhibit toroidal dipolar excitations.
Mechanism of deuterium addition and exchange with propene over Ni/SiO2 and Pt/SiO2 catalysts at low temperatures (1987)

The mechanism of the deuterium addition and exchange reaction of propene over Ni/SiO2 and Pt/SiO2 has been studied by applying microwave spectroscopy as well as kinetic measurements. The associative mechanism prevails in the presence of gaseous deuterium, while the dissociative mechanism operates in its absence. Over the Ni catalyst, the central carbon C2 of propene is most active for exchange and n-propyl (associative) and isopropenyl (dissociative) species are the predominant intermediates. Over the Pt catalyst, the terminal methylene carbon C1 is most active and isopropyl and n-propenyl species are the predominant intermediates.
Microoptomechanical pumps assembled and driven by holographic optical vortex arrays (2004)

Beams of light with helical wavefronts can be focused into ring-like optical traps known as optical vortices. The orbital angular momentum carried by photons in helical modes can be transferred to trapped mesoscopic objects and thereby coupled to a surrounding fluid. We demonstrate that arrays of optical vortices created with the holographic optical tweezer technique can assemble colloidal spheres into dynamically reconfigurable microoptomechanical pumps assembled by optical gradient forces and actuated by photon orbital angular momentum.
Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) (2012)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC) and carotid intimal medial thickness (C-IMT) provide information about the burden of disease. However, despite multiple validation studies of CAC, and C-IMT, these modalities do not accurately assess plaque characteristics, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events. [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity, an important source of cellular inflammation in vessel walls. More recently, we and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy as well as longer term therapeutic lifestyle changes (16 months). The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.
Release of nitric oxide during the T cell-independent pathway of macrophage activation. Its role in resistance to Listeria monocytogenes (1993)

Immunodeficient mice are remarkably resistant to Listeria monocytogenes (LM) infection. We examined the role that nitric oxide (NO.) plays in the CB-17/lcr SCID (SCID) response to LM. SCID spleen cells produced large quantities of NO. (as measured by nitrite formation) when incubated in the presence of heat-killed LM. NO. production was dependent on the release of IFN-gamma by the SCID NK cells. When tested directly, macrophages produced large quantities of nitrite in response to LM, but only in the presence of IFN-gamma. The production of NO. induced by LM was not affected by neutralizing antibodies to TNF or IL-1. The production of NO. was inhibited by addition of either of two inhibitors of NO.synthase, NG-monomethyl arginine, or aminoguanidine. In a different situation, NK cells that were stimulated by TNF and Listeria products to release IFN-gamma did not produce NO.. Macrophages cultured with IFN-gamma killed live LM. This increased killing of LM was significantly inhibited by amino-guanidine. In vivo, administration of aminoguanidine resulted in a marked increase in the mortality and spleen bacterial loads of LM-infected SCID or immunocompetent control mice. We conclude that NO. is a critical effector molecule of T cell-independent natural resistance to LM as studied in the SCID mouse, and that the NO.-mediated response is essential for both SCID and immunocompetent host to survive after LM infection.
Consistent and Heritable Alterations of DNA Methylation Are Induced by Tissue Culture in Maize (2014)

Abstract Plants regenerated from tissue culture and their progenies are expected to be identical clones, but often display heritable molecular and phenotypic variation. We characterized DNA methylation patterns in callus, primary regenerants, and regenerant-derived progenies of maize using immunoprecipitation of methylated DNA (meDIP) to assess the genome-wide frequency, pattern, and heritability of DNA methylation changes. Although genome-wide DNA methylation levels remained similar following tissue culture, numerous regions exhibited altered DNA methylation levels. Hypomethylation events were observed more frequently than hypermethylation following tissue culture. Many of the hypomethylation events occur at the same genomic sites across independent regenerants and cell lines. The DNA methylation changes were often heritable in progenies produced from self-pollination of primary regenerants. Methylation changes were enriched in regions upstream of genes and loss of DNA methylation at promoters was associated with altered expression at a subset of loci. Differentially methylated regions (DMRs) found in tissue culture regenerants overlap with the position of naturally occurring DMRs more often than expected by chance with 8% of tissue culture hypomethylated DMRs overlapping with DMRs identified by profiling natural variation, consistent with the hypotheses that genomic stresses similar to those causing somaclonal variation may also occur in nature, and that certain loci are particularly susceptible to epigenetic change in response to these stresses. The consistency of methylation changes across regenerants from independent cultures suggests a mechanistic response to the culture environment as opposed to an overall loss of fidelity in the maintenance of epigenetic states.
Elastic monitoring framework for cloud infrastructures (2012)

This study presents a scalable and elastic distributed system for monitoring cloud infrastructure based on a pure peer-to-peer architecture. Its distributed nature enables deploying long-living queries across the network to monitor a diverse set of entities and metrics, spanning across all layers of a cloud stack that can change rapidly. This allows for aggregating low-level metrics from operating systems, to higher-level application-specific metrics derived from services, databases or application log files. The observed metrics and information can be evaluated and used to reliably trigger policies to automate complex management tasks within a cloud environment. The architecture incorporates a query framework for obtaining high-level information and a policy framework to provide self-management capabilities to monitored cloud infrastructure. The system has been implemented as a proof of concept. Details and statistical results are provided to validate the scalability of the underlying architecture.
Silicon nitride microclips for the kinematic location of optic fibres in silicon V-shaped grooves (1998)

Flexible silicon nitride clips are used to hold single mode optical fibres in position in grooves etched in silicon substrates to connect either subsurface or surface mounted optical components. The fabrication process for the buried fibre connector requires only one lithographic step, and a silicon substrate coated with a 3 m thick silicon nitride film. The light coupled between two single mode optic fibres buried in the same V groove has been measured as a function of the separation of the ends of the fibres. The Young's modulus and mechanical properties of silicon nitride from various sources have been measured using the clips. In another process using two lithographic steps a clipped fibre is made having the fibre core level with the silicon surface or up to 20 m above it, and the tolerances are sufficiently tight for optical system manufacture. Light coupling has been demonstrated between a semiconductor laser and a fibre. The clip technology is versatile and tolerant of lateral and angular misalignments during insertion. Fabrication and mechanical design rules for the silicon nitride clip technology are summarized, and possible applications in fibre connection, waveguide sensor and telecommunication systems are discussed.
Histamine H1 and H4 receptor expression on the ocular surface of patients with chronic allergic conjunctival diseases (2017)

H4R is useful as biomarkers of allergic inflammation on ocular surfaces. Most notably, H4R expressed on eosinophils is useful as a biomarker of eosinophilic inflammation of the ocular surface.
Query processing issues in object-oriented database system-preliminary ideas (2002)

Object-oriented database technology is being developed to provide support for advanced applications such as engineering databases, office information systems, and knowledge bases. Successful deployment of these systems requires the provision of full set of features and capabilities found in traditional data managers (e.g., relational systems). An important feature is a declarative query language and its associated query processor. Development of query models and design of query processors is well understood in traditional database management systems. However, the task is complicated in object-oriented systems due to the richness of the data model. The query models necessarily become more complex and their optimization significantly more difficult. The author discusses the issues that need to be considered in the development of query models and in the implementation of query processors in object-oriented database systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Camptocormia in Parkinson's Disease (2010)

Objectives. Abnormalities of posture represent one of the main features of Parkinson's disease (PD). Among them, camptocormia has been considered as rare in PD. We investigated frequency and clinical features of camptocormia in PD patients. Methods. 153 PD patients (mean 68.5 ± 10.7 years old, duration 5.9 ± 2.4 years) outpatiently recruited. After neurologic examination, patients were rated on the Unified PD Rating Scale motor scale (UPDRS Part III), minimental state examination (MMSE). Also we evaluated patients with camptocormia by MRI. Of the 153 PD patients, 27 had camptocormia (mean age, 67.9 ± 7.9 years old; disease duration, 6.1 ± 3.9 years). For further evaluation, we recruited age- and sex-matched 27 PD patients without camptocormia (11 men and 16 women; mean age ± SD, 69.2 ± 10.1 years, duration 6.0 ± 2.7 years) These selected 54 patients completed several self-assessments. Lumbar and thoracic paraspinal muscles were studied by EMG. Results. There were no significant differences in age, duration, severity, and drug dose between patients with and without camptocormia. Analysis of NMSS subitems indicated that PD patients tended to show lower scores for sleep/fatigue, attention/memory, and miscellaneous items. Conclusions. We found significant differences concerning nonmotor signs and symptoms evaluated by FAB, PDQ-8, FSQ, VAS-F, and NMSS between patients with and without camptocormia. Our findings indicate that camptocormia is a relatively common sign in PD and that patients with camptocormia scores on the PDQ-8 compared with PD patients without camptocormia. This suggests that improvements in camptocormia of PD patients may improve their QOL.
产生强天气的中尺度对流系统—MCCs,中-β系统和大型对流线的环境场之比较研究 (1991)

1.引言由卫星观测提供的新的宏观远景已经证实了深厚对流云及其伴随的强天气通常被组织在各种具有中尺度空间和时间的结构里。这些结构中的大部分如Maddox(1980)定义的近似圆形的中-α尺度的中尺度对流复合体(MCCs)。还有另一种中-β系统,它们在类似的形势里发展,但其大小或生命史都不及MCCs。有些系统发展成非常长的对流线,它的面积较大,并
Preparation and Characterization of γ-Al<sub>2</sub>O<sub>3</sub> with Rich Brønsted Acid Sites and Its Application in the Fluid Catalytic Cracking Process (2014)

The objective of this work is to investigate the surface acidity of γ-Al2O3 after modification and its application in reducing coke formation in the fluid catalytic cracking (FCC) process. γ-Al2O3 with rich Brönsted acid sites and reduced Lewis acid sites was prepared by the sol–gel method using NH4BF4 as a modifier to develop a new functional material to adjust surface acidity. N2 sorption, powder X-ray diffraction (XRD), 27Al magic angle spinning nuclear magnetic resonance (27Al MAS NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were used to characterize the structure and surface properties of the prepared γ-Al2O3. The results showed that partial fluorination of the surface of γ-Al2O3 generated small quantities of a pyrochlore-type phase which was formed mainly by substitution of the OH group on six-coordinated aluminum with fluorine. In addition, boron insertion in the structure of γ-Al2O3 reduced the Lewis acid concentration and increased the surface area of γ-Al2O3. After aging in an alkaline solution with a F/Al mole ratio of 0.45, the modified γ-Al2O3 demonstrated high surface area (276 m2/g) with gamma alumina structure due to the synergistic effect of boron and fluorine doping by using NH4BF4. However, most importantly the modified γ-Al2O3 exhibited the high Brönsted/Lewis acid ratio of 0.75. In the bench-scale tests with heavy oil, the modified γ-Al2O3 showed good catalytic performance by increasing conversion of heavy oil to light oil while reducing coke formation.
Signal peptide cleavage regions. Functional limits on length and topological implications. (1994)

As a first step toward understanding the topology of the signal peptide with respect to the membrane during the protein export process, we have examined the constraints on the length of the cleavage region needed to achieve signal peptidase recognition and cleavage. Using the signal peptide of Escherichia coli alkaline phosphatase, a series of cleavage region mutants has been constructed. Variations in length were brought about by replacing the wild type cleavage region of the signal peptide with polymers of increasingly more residues. In each case, alanine residues are used exclusively in the -1 and -3 positions to provide only one viable cleavage site. Glutamine residues are used in all other positions in order to vary the length from 3 to 13 total residues. Analysis of these mutants revealed that cleavage regions ranging from 3 to 9 residues are completely and efficiently processed. The extent of processing drops substantially thereafter, with no processing observed for signal peptides with 13-residue long cleavage regions. A second mutant with a 13-residue long cleavage region was designed and analyzed to ensure that the lack of processing reflected a cleavage problem and not a translocation defect. The results are consistent with the notion that the signal peptidase active site is in close proximity to the periplasmic surface of the inner membrane and that interaction of the cleavage region with the signal peptidase probably depends on, and is constrained by, other interactions involving the signal peptide.
Structural analysis of lipopolysaccharides from <i>Haemophilus influenzae</i> serotype f (2003)

Structural elucidation of the lipopolysaccharide (LPS) from three serotype f Haemophilus influenzae clinical isolates RM6255, RM7290 and RM6252 has been achieved using NMR spectroscopy techniques and ESI-MS on O-deacylated LPS and core oligosaccharide material (OS) as well as ESI-MSn on permethylated dephosphorylated OS. This is the first study to report structural details on LPS from serotype f strains. We found that the LPSs of all strains were highly heterogeneous mixtures of glycoforms expressing the common H. influenzae structural element l-alpha-d-Hepp-(1-->2)-[PEtn-->6]-l-alpha-d-Hepp-(1-->3)-[beta-d-Glcp-(1-->4)]-l-alpha-d-Hepp-(1-->5)-[PPEtn-->4]-alpha-Kdo-(2-->6)-lipid A with variable length of OS chains linked to each of the heptoses. The terminal heptose (HepIII) in RM6255 is substituted at the O-3 position by a beta-d-Glcp residue whereas HepIII in strains RM7290 and RM6252 is substituted at O-2 by the globoside unit (alpha-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-beta-d-Glc) or truncated versions thereof. The central heptose (HepII) is substituted by an alpha-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-beta-d-Glcp-(1-->4)-alpha-d-Glcp unit in RM7290 and RM6252 or truncated versions thereof. Strain RM6255 does not express galactose in its LPS and only shows a cellobiose unit elongating from HepII (beta-d-Glcp-(1-->4)-alpha-d-Glcp). ESI-MSn on dephosphorylated and permethylated OS provided information on the existence of additional minor isomeric glycoforms.
Folding of the Amino-terminal Domain of Apolipoprotein B Initiates Microsomal Triglyceride Transfer Protein-dependent Lipid Transfer to Nascent Very Low Density Lipoprotein (1997)

The initial assembly of apolipoprotein B100 (apoB) into lipoprotein particles occurs cotranslationally. To examine steps required to initiate this process, the intracellular folding and assembly of the amino-terminal 28% of apoB (apoB28) was examined using several criteria including nonreducing gel electrophoresis, sensitivity to dithiothreitol (DTT)-mediated reduction, and buoyant density gradient centrifugation. In hepatoma cells, after a 1-min pulse with radiolabeled amino acids, labeled apoB28 migrated during gel electrophoresis in the folded position and was resistant to reduction in vivo with 2 mM DTT. A similar rate and extent of folding was observed in Chinese hamster ovary cells, a microsomal triglyceride transfer protein (MTP)-negative cell line that can neither lipidate nor efficiently secrete apoB28. Amino-terminal folding of apoB28 was essential for its subsequent intracellular lipidation as apoB28 synthesized in hepatoma cells under reducing conditions remained lipid poor (d > 1.25 g/ml) and was retained intracellularly. Upon DTT removal, reduced apoB28 underwent a process of rapid (t1/2 approximately 2 min) post-translational folding followed by a slower process of MTP-dependent lipidation. As with the cotranslational assembly pathway, post-translational lipidation of apoB28 displayed a strict dependence upon amino-terminal folding. We conclude that: 1) folding of the amino-terminal disulfide bonded domain of apoB is achieved prior to the completion of translation and is independent of MTP and events associated with buoyant lipoprotein formation and 2) domain-specific folding of apoBs amino-terminal region is required to initiate MTP-dependent lipid transfer to nascent apoB in the hepatic endoplasmic reticulum.