289 research outputs found
data analysis 2009–2018
Get PDFBACKGROUND
Allergic contact dermatitis caused by shoes is common and new relevant allergens have been identified.
OBJECTIVES
To investigate the pattern of type IV sensitization in patients with suspected allergic contact dermatitis of the feet related to shoes as a presumed culprit trigger.
METHODS
Retrospective analysis of data of the Information Network of Departments of Dermatology (IVDK), 2009-2018.
RESULTS
Six hundred twenty-five patients with presumed shoe dermatitis were identified in a cohort of 119 417 patients. Compared to patients with suspected contact sensitization from other allergen sources (n = 118 792), study group patients were more frequently sensitized to potassium dichromate (10.8% vs 3.5%), colophony (7.2% vs 3.7%), mercaptobenzothiazole (MBT; 4.0% vs 0.6%), mercapto mix (4.6% vs 0.6%), and p-tert-butylphenol formaldehyde resin (1.6% vs 0.5%). Sensitizations to urea formaldehyde resin, melamine formaldehyde resin, glutaraldehyde, tricresyl phosphate, and phenyl glycidylether were rare. Moreover, reactions to compounds in the leather or textile dyes test series were scarce.
CONCLUSION
A distinct sensitization pattern was observed in patients with suspected allergy to shoe materials. Although substances with low sensitization rates should be removed from the leather and shoe patch test series, novel potential allergens should be added
Current patch test results in consecutive patients with, and chemical analysis of, disperse blue (DB) 106, DB 124, and the mix of DB 106 and 124
No full textDisperse blue (DB) 106 and 124 are important textile dye allergens. However, the dye raw material is impure, leading to uncertainty regarding the actual patch test (PT) concentration. To examine, (i) the allergen content of previously and currently used DB 106 and 124 and a respective mix, and (ii) the frequency of positive PT reactions to the DB 106/124 mix and to the single compounds in consecutive PT patients. High performance liquid chromatography (HPLC) analysis and purification of DB 106 and 124, respectively. Descriptive analysis of PT data from the Information network of departments of dermatology obtained between January 2003 and December 2005. Retrospectively, 2 batches of the DB 106/124 mix proved to contain an amount of allergen different to the 1 declared (based on information of suppliers of raw material). However, since February 2005, DB 106 and 124, respectively, are available at a reliable concentration of 0.3% petrolatum. In 2005, the prevalence of positive PT reactions to both the mix (0.89%) and the single constituents combined (0.56%) did not qualify them for inclusion in the standard series. Quality control, providing accurate test concentrations of allergens based on technical grade purity raw materials is necessary for valid diagnosis of contact allergy and comparable epidemiological data
SHOTGLAS
No full textThe presence of extreme horizontal branch (EHB) and blue hook stars in some Galactic globular clusters (GGCs) constitutes one of the remaining mysteries of stellar evolution. While several evolutionary scenarios have been proposed to explain the characteristics of this peculiar population of evolved stars, their observational verification has been limited by the availability of spectroscopic data for a statistically significant sample of such objects in any single GGC. We recently launched the SHOTGLAS project with the aim of providing a comprehensive picture of this intriguing stellar population in terms of spectroscopic properties for all readily accessible GGCs hosting an EHB. In this first paper, we focus on ω Cen, a peculiar, massive GGC that hosts multiple stellar populations. We use non-LTE model atmospheres to derive atmospheric parameters (Teff, log g and N(He)/N(H)) and spectroscopic masses for 152 EHB stars in the cluster. This constitutes the largest spectroscopic sample of EHB stars ever analyzed in a GGC and represents ≈20% of the EHB population of ω Cen. We also search for close binaries among these stars based on radial velocity variations. Our results show that the EHB population of ω Cen is divided into three spectroscopic groups that are very distinct in the Teff − helium abundance plane. The coolest sdB-type stars (Teff ≲ 30 000 K) have a hydrogen-rich atmosphere, populate the theoretical EHB region in the Teff − log g plane, and form 26% of our sample. The hottest sdO-type stars (Teff ≳ 42 000 K) make up 10% of the sample, have a hydrogen-rich atmosphere and are thought to be in a post-EHB evolutionary phase. The majority of our sample is found at intermediate temperatures and consists of sdOB stars that have roughly solar or super-solar atmospheric helium abundances. It is these objects that constitute the blue hook at V > 18.5 mag in the ω Cen color-magnitude diagram. Interestingly, the helium-enriched sdOBs do not have a significant counterpart population in the Galactic field, indicating that their formation is dependent on the particular environment found in ω Cen and other select GGCs. Another major difference between the EHB stars in ω Cen and the field is the fraction of close binaries. From our radial velocity survey we identify two binary candidates, however no orbital solutions could be determined. We estimate an EHB close binary fraction of ≈5% in ω Cen. This low fraction is in line with findings for other GGCs, but in sharp contrast to the situation in the field, where around 50% of the sdB stars reside in close binaries. Finally, the mass distribution derived is very similar for all three spectroscopic groups, however the average mass (0.38 M⊙) is lower than that expected from stellar evolution theory. While this mass conundrum has previously been noted for EHB stars in ω Cen, it so far appears to be unique to that cluster
Cognitive Theory and the Selling of the Flat Tax
Get PDFIn this article, Professor Deborah A. Geier brings to bear the insights of Professor Edward J. McCaffery, regarding the interaction of cognitive theory and the tax world, to the flat tax proposal. The article explores how the perceptual biases described by Professor McCaffery might affect both taxpayers\u27 impressions of the contours of the proposed tax base and their behavioral reponses to the same incentive. The author warns that any errors in her application of Professor McCaffery\u27s work to the flat tax are entirely her own
Observation of a resonance in the spin-orbit scattering of 5(s, p) impurities in Mg and Cu
No full textObservation of a resonance in the spin-orbit scattering of 5 (sip) impurities in Mg and Cu / G. Bergmann ; S. Geier. - In: Solid state communications. 87. 1993. S. 471-47
Texture estimates by means of components: dedicated to Professor Dr. rer. nat. Dr. h.c. Hans-Joachim Bunge on the occasion of his 65th birthday
No full textTexture estimates by means of components / S. Geier ... - In: Zeitschrift für Metallkunde. 85. 1994. S. 545-55
Fels - Geier - Eltern : Untersuchungen zum Gottesbild des Moseliedes (Dtn 32)
No full textDas Moselied gilt wegen seiner kompositorisch zentralen Position am Ende des Pentateuch und seiner poetischen Form als theologischer Spitzentext. Die Autorin fragt nach der Konstruktion des Gottesbildes durch die drei zentralen Metaphern Fels, Geier und Eltern. Nach einer Analyse der Gesamtstruktur des Liedes untersucht sie die Metaphern in zwei Schritten. Dabei bildet die Einordnung der Metaphern in den literarischen Kontext der Hebräischen Bibel den Hintergrund der semantischen und intertextuellen Untersuchung der Metaphern im Moselied. Die Studie ermöglicht damit - jenseits der verbreiteten Dichotomie von »positiven« und »negativen « Gottesbildern - einen differenzierteren Blick auf die Spannungen und Komplexitäten des alttestamentlichen Gottesbildes.Due to its compositionally central position at the end of the Pentateuch and its poetical form, the Song of Moses is counted among the seminal theological texts of the Old Testament. The author explores the construction of the image of God by analysing the three central metaphors of the rock, vulture, and parents. A synchronic and diachronic analysis of the overall structure is followed by an analysis of the metaphors in the light of the history of motives, which places it in the literary context of the Hebrew Bible, as well as opening up the perspective of deutercanonical and Qumran literature, and taking into account iconographic and textual sources from the Ancient Near East. The purpose is to offer a differentiated consideration of the tensions and complexities of the Old Testament image of God beyond the dichotomy of "positive" and "negative"
Transition Metal Complexes and Main Group Frustrated Lewis Pairs for Stoichiometric and Catalytic P-P and H-H Bond Activation
Get PDFStoichiometric and catalytic small molecule activation reactions are vital for the synthesis of new materials. The activation of phosphorus-hydrogen or phosphorus-phosphorus bonds allows for the facile synthesis of new phosphorus-containing molecules for a wide variety of applications.1
An investigation of the P-H dehydrocoupling reaction was undertaken utilizing two rhodium(I) based catalysts. Over the course of this investigation it was found that the Rh(I) systems were also active catalysts for the reverse reaction: phosphorus-phosphorus bond hydrogenation (and hydrosilylation). This reaction was exploited for the synthesis of novel phosphines from P-P bound species. Molecules with P-P bonds were reacted in a stoichiometric fashion with the catalyst precursor, producing a variety of novel species with interesting bonding features which shed some light on the reaction mechanism.
Following the discovery in 2006 that a linked phosphine-borane system could reversibly activate hydrogen2 a tremendous effort has been put forth to understand and expand this unprecedented reactivity.3,4 This new archetype for metal-free small molecule activation, containing a bulky Lewis acid and Lewis base which are unable to bond directly due to steric repulsion, has been termed a “frustrated Lewis pair” (FLP).3,4
The FLP concept is expanded to include bulky P-P bound species, pyridines and P-O bound Lewis bases as partners for B(C6F5)3. In some cases small molecule activation produced ion pairs or zwitterions related to those found for reactions with tertiary phosphines,3,4 but in others novel reaction pathways were discovered including phosphorus-phosphorus bond cleavage, catalytic hydrogenations and the formation of novel intramolecular FLPs. An unexpected situation was observed for the pair of 2,6-lutidine with B(C6F5)3, where adduct formation was observed along with free Lewis acid and base, but H2 activation by the FLP proceeded smoothly.
Covalently bound phosphinoboranes of the general formula R2PB(C6F5)2 are synthesized. While systems with small R groups dimerized, monomers existed for cases with bulkier R groups. These monomers were found to exhibit extraordinarily short phosphorus-boron bonds yet were still capable of H2 activation analogous to bimolecular phosphine-borane systems. These systems also showed unique reactivity with Lewis acids and Lewis bases.
This work further demonstrates the broad and general utility of the FLP concept in the synthesis of new materials and in catalytic transformations.Ph
Ein Gas-Kinetic Scheme Ansatz zur Modellierung und Simulation von Feuer auf massiv paralleler Hardware
Get PDFThis work presents a simulation approach based on a Gas Kinetic Scheme (GKS) for the simulation of fire that is implemented on massively parallel hardware in terms of Graphics Processing Units (GPU) in the framework of General Purpose computing on Graphics Processing Units (GPGPU).
Gas kinetic schemes belong to the class of kinetic methods because their governing equation is the mesoscopic Boltzmann equation, rather than the macroscopic Navier-Stokes equations.
Formally, kinetic methods have the advantage of a linear advection term which simplifies discretization.
GKS inherently contains the full energy equation which is required for compressible flows.
GKS provides a flux formulation derived from kinetic theory and is usually implemented as a finite volume method on cell-centered grids.
In this work, we consider an implementation on nested Cartesian grids.
To that end, a coupling algorithm for uniform grids with varying resolution was developed and is presented in this work.
The limitation to local uniform Cartesian grids allows an efficient implementation on GPUs, which belong to the class of many core processors, i.e. massively parallel hardware.
Multi-GPU support is also implemented and efficiency is enhanced by communication hiding.
The fluid solver is validated for several two- and three-dimensional test cases including natural convection, turbulent natural convection and turbulent decay.
It is subsequently applied to a study of boundary layer stability of natural convection in a cavity with differentially heated walls and large temperature differences.
The fluid solver is further augmented by a simple combustion model for non-premixed flames.
It is validated by comparison to experimental data for two different fire plumes.
The results are further compared to the industry standard for fire simulation, i.e. the Fire Dynamics Simulator (FDS).
While the accuracy of GKS appears slightly reduced as compared to FDS, a substantial speedup in terms of time to solution is found.
Finally, GKS is applied to the simulation of a compartment fire.
This work shows that the GKS has a large potential for efficient high performance fire simulations.Diese Arbeit präsentiert einen Simulationsansatz basierend auf einer gaskinetischen Methode (eng. Gas Kinetic Scheme, GKS) zur Simulation von Bränden, welcher für massiv parallel Hardware im Sinne von Grafikprozessoren (eng. Graphics Processing Units, GPUs) implementiert wurde.
GKS gehört zur Klasse der kinetischen Methoden, die nicht die makroskopischen Navier-Stokes Gleichungen, sondern die mesoskopische Boltzmann Gleichung lösen.
Formal haben kinetische Methoden den Vorteil, dass der Advektionsterms linear ist.
Dies vereinfacht die Diskretisierung.
In GKS ist die vollständige Energiegleichung, die zur Lösung kompressibler Strömungen benötigt wird, enthalten.
GKS formuliert den Fluss von Erhaltungsgrößen basierend auf der gaskinetischen Theorie und wird meistens im Rahmen der Finiten Volumen Methode umgesetzt.
In dieser Arbeit betrachten wir eine Implementierung auf gleichmäßigen Kartesischen Gittern.
Dazu wurde ein Kopplungsalgorithmus für die Kombination von Gittern unterschiedlicher Auflösung entwickelt.
Die Einschränkung auf lokal gleichmäßige Gitter erlaubt eine effiziente Implementierung auf GPUs, welche zur Klasse der massiv parallelen Hardware gehören.
Des Weiteren umfasst die Implementierung eine Unterstützung für Multi-GPU mit versteckter Kommunikation.
Der Strömungslöser ist für zwei und dreidimensionale Testfälle validiert.
Dabei reichen die Tests von natürlicher Konvektion über turbulente Konvektion bis hin zu turbulentem Zerfall.
Anschließend wird der Löser genutzt um die Grenzschichtstabilität in natürlicher Konvektion bei großen Temperaturunterschieden zu untersuchen.
Darüber hinaus umfasst der Löser ein einfaches Verbrennungsmodell für Diffusionsflammen.
Dieses wird durch Vergleich mit experimentellen Feuern validiert.
Außerdem werden die Ergebnisse mit dem gängigen Brandsimulationsprogramm FDS (eng. Fire Dynamics Simulator) verglichen.
Die Qualität der Ergebnisse ist dabei vergleichbar, allerdings ist der in dieser Arbeit entwickelte Löser deutlich schneller.
Anschließend wird das GKS noch für die Simulation eines Raumbrandes angewendet.
Diese Arbeit zeigt, dass GKS ein großes Potential für die Hochleistungssimulation von Feuer hat
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