bluuebunny/crossref_metadata_2025_split huggingface dataset:
The luminosity index for M stars and the distance to the LMC
Authors: Schmidt‐Kaler TH. , Oestreicher M. O. 
Published: July 2007

AbstractOn the bases of the new classification system introduced by Malyuto et al. (1997) a new technique to determine luminosities for M type stars has been established. Due to the lack of accurate distances and their inhomogeneity especially for supergiants the intrinsic scatter is rather high with 0.4 to 0.5 mag. The uncertainty of the zeropoint is 0.07 to 0.08 mag.Applying our new method to M supergiant members of the LMC a distance modulus of 18.34 ± 0.09 mag is derived which agrees well with recent work. The luminosities of the stars range from those of galactic Iab to those of Ia‐Ia‐0 supergiants, i.e. the upper luminosity limit does not exceed that of their galactic counterparts.Like the CaII H and K emission technique of Wilson & Bappu (1957), for which a revised calibration is given, the new method spans an extremely wide range of luminosities. It is less universal, as it can be applied to M stars only, but not to K stars. On the other hand the Wilson‐Bappu‐method requires high resolution spectroscopy so that it is restricted to bright stars in our Galaxy. Our new technique may be applied to faint stars in nearby galaxies since it requires low resolution spectroscopy only.
Hydromagnetic stability analysis of a Solar prominence suspended in an external horizontal magnetic field
Authors: GalindoTrejo J. 
Published: July 2007

AbstractAmong the observed characteristics of quiescent solar prominences, stability is perhaps the most important requirement for theoretical models of these coronal structures. Only stable equilibria can explain the presence of such cool and dense plasma sheets for extended periods of time. Utilizing the MHD‐Energy Principle (Bernstein et al. 1958) we investigate the linear stability properties of the two‐dimensional prominence equilibrium of Osherovich (1985). Incorporating a finite magnetic energy and a continous magnetic field, this model takes into account explicitly an external horizontal magnetic field in which the prominence is suspended. The presented numerical calculations indicate that the prominence model of Osherovich is stable and can explain the main features of reported oscillations. Instabilities occur only when model parameters are unrealistic for physical conditions in solar prominences.
N‐ Versus P‐Coordination in Bis(amino)cyclodiphosph(III)azane Complexes of Aluminum
Authors: Rastätter Marcus , Roesky Peter W. , Gudat Dietrich , Deacon Glen B. , Junk Peter C. 
Published: July 2007

AbstractThe reaction of the bis(amino)cyclodiphosph(III)azane, cis‐{(tBuNH)2(PNtBu)2}, with AlMe3, AlClMe2, AlCl2Me, and AlCl3 is reported. The less Lewis acidic compound AlMe3 forms the adduct cis‐[(tBuNH)2(PNtBu){P(⋅AlMe3)NtBu}] (1), in which the aluminum atom is exclusively coordinated to one phosphorus atom. At elevated temperatures AlMe3 undergoes migratory exchange between the two phosphorus atoms, but no methane elimination is observed. By using the more Lewis acidic compound AlClMe2 the P‐coordinated compound cis‐[(tBuNH)2(PNtBu){P(⋅AlClMe2)NtBu}] (2) can be obtained at low temperatures. Compound 2 rearranges irreversibly to a product in which the AlClMe2 group is coordinated by one exo‐cyclic nitrogen atom. A concomitant 1,2‐H shift from this nitrogen atom onto the phosphorus atom is observed. The N‐coordinated rearrangement product slowly decomposes via a PN bond cleavage in solution. Reaction of the even more Lewis acidic compounds AlCl2Me and AlCl3 finally led to stable adducts, cis‐[(tBuNH)(PNtBu)(tBuN⋅AlCl2Me){P(H)NtBu}] (3), and cis‐[(tBuNH)(PNtBu)(tBuN⋅AlCl3){P(H)NtBu}] (4), in which the aluminum atoms are N‐coordinated by a tBuNPH unit.
Alternative Validation of a LC‐MS/MS‐Multi‐Method for Pesticides in Drinking Water
Authors: Müller Alexander , Flottmann Dirk , Schulz Wolfgang , Seitz Wolfram , Weber Walter H. 
Published: July 2007

AbstractThe development of instrumental analytics such as the LC‐MS/MS has made it possible to quickly determine many component concentrations in a single chromatogram. However, the validation of such multi‐methods needs new strategies for robustness and optimization. Statistical execution of analytical tests is one tool that can be utilized to meet this requirement. A Central Composite Design (CCD) was utilized for the validation of an LC‐MS/MS multi‐method for 84 analytes. The experimental design includes six design variables and two non‐design variables (response variables). Concentration, ionization temperature, dwell time, gradient, flow (of eluent), and spraying/curtain gas (continuous design variables) were varied on five different levels; the whole design encompassed 91 runs. To investigate the robustness of a LC‐MS/MS method both peak sensitivity and chromatographic separation had to be verified. Therefore, two non‐design variables were necessary. The distribution of the peaks over analysis time was applied to describe the quality of the chromatographic separation. The sensitivity was described with the signal to noise ratio (S/N). The evaluation of the measured data was accomplished with the Analysis of Variance (ANOVA) and the Response Surface Methodology (RSM). Three main effects (concentration, ionization temperature, dwell time) and no significant interaction effect were found for the response variable “S/N”. The variables of concentration, ionization temperature, and dwell time had no significant effects for the response variable “S/N”. The ANOVA of the response variable chromatographic separation abandoned no significant effects as well. Therefore, robustness of the method can be guaranteed for all non significant design variables.
Effect of obesity on prostate‐specific antigen recurrence after radiation therapy for localized prostate cancer as measured by the 2006 Radiation Therapy Oncology Group‐American Society for Therapeutic Radiation and Oncology (RTOG‐ASTRO) Phoenix consensus definition
Authors: Stroup Sean P. , Cullen Jennifer , Auge Brian K. , L'Esperance James O. , Kang Song K. 
Published: July 2007

AbstractBACKGROUND.Given the limited data regarding the impact of obesity on treatment outcomes after external beam radiation therapy (EBRT) for the definitive treatment of prostate cancer, the authors sought to evaluate the effect of obesity as measured by body mass index (BMI) on biochemical disease recurrence (BCR) using the most current 2006 Radiation Therapy Oncology Group‐American Society for Therapeutic Radiation and Oncology (RTOG‐ASTRO) Phoenix consensus definition (prostate‐specific antigen [PSA] nadir + 2 ng/mL).METHODS.A retrospective cohort study identified men who underwent primary EBRT for localized prostate cancer between 1989 and 2003 using the Center for Prostate Disease Research (CPDR) Multi‐center National Database. BMI was calculated (in kg/m2) and the data were analyzed. Univariate and multivariate Cox proportional hazards regression analyses were used to determine whether BMI significantly predicted BCR.RESULTS.Of the 1868 eligible patients, 399 (21%) were obese. The median age of the patients and pretreatment PSA level were 70.2 years and 8.2 ng/mL, respectively. Of 1320 patients for whom data were available with which to calculate PSA recurrence (PSA nadir + 2 ng/mL), a total of 554 men (42.0%) experienced BCR. On univariate analysis, BMI was found to be an independent predictor of PSA recurrence (P = .02), as was race, pretreatment PSA level, EBRT dose, clinical T classification, Gleason score, PSA nadir, and the use of androgen‐deprivation therapy (ADT). On multivariate analysis, BMI remained a significant predictor of BCR (P = .008).CONCLUSIONS.To the authors' knowledge, this is the first study to report the association between obesity and BCR after EBRT for localized prostate cancer as measured by the updated 2006 RTOG‐ASTRO definition. A higher BMI is associated with greater odds of BCR after undergoing definitive EBRT. Cancer 2007. Published 2007 by the American Cancer Society.
A peak load control‐based orchestration system for stable execution of hybrid services
Authors: Lee Yonghwan , Min Dugki 
Published: July 2007

AbstractThe prosperity of Internet results in a workflow executing engine's performance instability due to the request congestion for a short period of time. This paper proposes a peak load control (PLC) based orchestration system that can stably execute hybrid services. The PLC mechanism uses the delay time algorithm for controlling a BPEL engine's heavy peak load caused by the request congestion for a short period of time. In order to prove the stable performance of the PLC‐based orchestration system, we analyze the proposed delay time algorithm. According to our experimental results, the proposed delay time algorithm can stably execute structured activities of WSBPEL specification in heavily overloaded state after the saturation phase and has an effect on controlling the states of peak load. In this paper, we also describe a hybrid service architecture model that can represent both Web Services and existing EAs as same type of services. Copyright © 2007 John Wiley & Sons, Ltd.
Surfactant Fouling of Nanofiltration Membranes: Measurements and Mechanisms
Authors: Boussu Katleen , Kindts Céline , Vandecasteele Carlo , Van der Bruggen Bart 
Published: July 2007

AbstractFouling of nanofiltration membranes is studied during filtration of aqueous surfactant solutions under different conditions. To this purpose, four typical nanofiltration membranes (Desal51HL, NF270, NTR7450 and NFPES10) and three typical surfactants (nonionic neodol, anionic SDBS and cationic cetrimide) are selected. Fouling is studied as a function of the surfactant concentration, with and without addition of an electrolyte (NaCl), at different pH and when filtering a mixture of surfactants. Adsorption experiments and hydrophobicity measurements (to study the orientation of the surfactants on the membrane surface) are also performed under the different conditions. The least membrane fouling is found for the anionic surfactant SDBS, while for the cationic surfactant cetrimide very low relative fluxes are observed. Neodol shows an intermediate degree of fouling. Both hydrophobic and electrostatic interactions (in the case of ionic surfactants) between the membrane surface and the surfactant explain the degree of adsorption and hence fouling, as membrane fouling is correlated with the amount of adsorbed surfactant. The difference between cetrimide and SDBS becomes especially visible when changing the pH: increasing the pH leads not only to an opposite orientation of the adsorbed surfactants, but also to an opposite trend in adsorbed amount and membrane fouling. This study permits selection of an optimal nanofiltration membrane to recycle wastewater containing surfactants in the carwash industry. The optimal choice would be a hydrophilic membrane with a low molecular weight cut‐off and a small negative surface charge at neutral pH. Cationic surfactants in the wastewater should also be avoided as much as possible.
Zur statistischen Theorie der Diffusion geladener Teilchen
Authors: Ebeling Werner 
Published: July 2007

AbstractA diffusion equation for a charged particle in an oscillating electric field is derived. We start with the Liouville equation for the distribution function of the whole system consisting of the host fluid and the charged particle. In order to obtain the time evolution of the distribution function of the charged particle in the coordinate space we utilize the technique of projection operators developed by Zwanzig. We find frequency‐ independent diffusion coefficients D = ζ(0) and frequency‐dependent mobilities B = ζ(ω)/kT. in terms of the correlation function magnified image Here ζ is the microscopic velocity of the charged particle and the average is over the equilibrium distribution function of the fluid in the presence of this charged particle. Under appropriate circumstances the correlation function ζ (omega;) may be computed by means of the Langevin‐Kirkwood equation. The relation between our theory and that obtained by Lebowitz and Resibois is discussed. We further show that at higher concentrations of charged particles the gradient of the concentration must be replaced by the gradient of the local osmotic pressure. The theory is applied to ambipolar diffusion.
Lösung der linearisierten Wlassow‐Gleichung für ein anisotropes Elektronenplasma
Authors: Bachmann P. 
Published: July 2007

AbstractEs wird das Anfangswertproblem für die nichtrelativistische, linearisierte Wlassow‐Gleichung für ein Elektronenplasma in einem konstanten äußeren Magnetfeld untersucht. Diesem Anfangswertproblem ist eine Volterrasche Integralgleichung vom Faltungstyp für die Fourier‐Transformierte der Dichtestörung äquivalent. Mittels Laplace‐Transformation wird diese durch Berechnung des Resolventenkerns gelöst. Die Lösung, die nicht spezialisiert ist für bestimmte Verteilungsfunktionen, besteht wie für das magnetfeldfreie Plasma aus drei Anteilen: Der erste hängt nur von der Anfangsstörung ab; der zweite noch zusätzlich von der Gleichgewichtsverteilung; beide zeigen im allgemeinen kein zeitlich‐harmonisches Verhalten. Der dritte Teil hängt exponentiell von der Zeit ab, für ihn gilt eine “Dispersionsgleichung” (Landausche Lösung).Für die folgende Anfangsstörung: f1(χ,v, t = 0) = g(v⊥, v|) exp (ik1·χ) wird die Dichtestörung genauer untersucht, wobei dann noch für g(v⊥, v|) eine Bi‐Maxwell‐Verteilung angenommen wird. Die beiden ersten Anteile, die nach Partialschwingungen mit den Frequenzen nωc entwickelt werden, zeigen im allgemeinen ein Transient‐Verhalten. Für den Fall der senkrechten Ausbreitung zum Magnetfeld wird gezeigt, daß alle Lösungsteile das gleiche zeitliche Verhalten zeigen; insbesondere wird auch für die Landausche Lösung im allgemeinen keine Dispersionsgleichung existieren.Mit Hilfe des hergeleiteten Formalismus wird dann ein einfaches Anfangswertproblem für das kalte Plasma durchgerechnet.
Zur Theorie der künstlich erzeugten laufenden und stehenden Schichten. I
Authors: Fuchs Vladimir 
Published: July 2007

AbstractEs wird gezeigt, daß im stabilen Regime nichttriviale, zeitlich asymptotische Lösungen des Systems der inhomogenen partiellen Differentialgleichungen der Ionisationswellentheorie existieren. Mit Rücksicht auf die Eindeutigkeit dieser Lösungen ergeben sich hiermit für eine günstig gewählte Quelle einzig mögliche Darstellungen der Wellenerscheinungen, die in einem zeitlich dauernd und räumlich lokal gestörten Plasma der positiven Säule ablaufen. Einige Grundeigenschaften dieser Lösungen stimmen gut mit Beobachtungen überein, die bei Experimenten mit künstlich erzeugten stehenden und laufenden Schichten gewonnen wurden, welche hinter einer lokalen stationären oder periodischen Störung entstehen.
Zur Ausbreitung von Wellen kleiner Amplitude in einem unvollständig ionisierten Plasma II
Authors: Wilhelm Johannes , Wisliceny Johann 
Published: July 2007

AbstractIm ersten Teil unserer Arbeit [1] wurde unter dort im einzelnen angegebenen Bedingungen die Dispersionsgleichung (DpGl.) für ein Plasma hergeleitet, in welchem die Neutralteilchenkomponente wesentlich mit zu berücksichtigen ist (Abschnitt I). Die DpGl. wurde für fehlendes äußeres Magnetfeld (II) und für Wellenausbreitung parallel zu einem äußeren, homogenen und konstanten Magnetfeld (III) diskutiert. Nachstehend erfolgt die Diskussion der DpGl. für Ausbreitung der Wellen senkrecht zum äußeren Magnetfeld (IV)1). – Wir gebrauchen nachstehend die in [1] verwandten Bezeichnungen2). Zum Abschnitt IV wurden wie zu II und III einige Beispiele für Dispersionskurven berechnet und zwar für zwei der in I 4 beschriebenen Plasmen für jeweils zwei Werte der Feldstärke des äußeren Magnetfeldes. Zum Vergleich sind auch die Kurven für fehlendes Magnetfeld angegeben, die aus II und III übernommen wurden.
Experimentelle Ergebnisse zum stationären Anodenfall in der Niederdruck‐Edelgasentladung. Teil I
Authors: Zahn Rolf‐Jürgen , Schaal Günter 
Published: July 2007

AbstractNach einem Überblick zu den Anodenerscheinungen, den vorhandenen Modellvorstellungen und dem experimentellen Vorgehen im Anodengebiet der Niederdruckentladung wird über Ergebnisse von Anodenfallmessungen in Helium, Neon und Argon berichtet und ein qualitativer und quantitativer Vergleich mit der Theorie angeführt. Im Ergebnis wird auf deutliche Unterschiede zwischen Theorie und Experiment hingewiesen, deren Quellen in drei Problem‐komplexen bei der Beschreibung des Anodengebietes gesehen werden. Teil II der Arbeit unter‐nimmt es, durch gezielte Versuche Aussagen zu gewinnen, die zum vertieften Verständnis der anodischen Entladungserscheinungen beitragen können.
Modell der Plasmaexpansion
Authors: Hantzsche E. 
Published: July 2007

AbstractDie Expansion eines kleinen Plasmavolumens infolge der Absorption eines kurzen Energieimpulses wird durch ein einfaches Modell beschrieben, mit den Annahmen: alle physikalischen Zustandsgrößen werden durch ihre räumlichen Mittelwerte ersetzt, und Ausgangsgleichungen sind hauptsächlich die Energie‐ und Impulsbilanz des gesamten Plasmas. Die Anfangsphase wird als stationär betrachtet. Damit lassen sich explizite Ausdrücke für die Expansions‐geschwindigkeiten, die kinetische und thermische Energie des Plasmas, die Temperaturen und Drücke gewinnen. Obwohl diese Beziehungen nur Näherungen sind, kann man qualitative und — in begrenztem Maße — auch quantitative Aussagen ableiten. Beispielsweise liegt die kinetische Expansionsenergie zwischen 1/5 und 1/2 der absorbierten Gesamtenergie W0, und die mittlere Temperatur T wächst während der Expansion ∼ W02/5.
Die Geschwindigkeitsverteilung der Ionen in der Freifallsäule
Authors: Valentini H.‐B. 
Published: July 2007

AbstractThe velocity distribution of the ions in the positive column of the free‐fall type discharge is derived by means of the method of characteristics from collisionless Boltzmann equation extended by a source term in plane and cylindrical geometries. A homogeneous axial magnetic field and the initial distribution of ion velocities is taken into account. The formula of Tonks and Langmuir for ion density is reproduced in case of vanishing initial velocity of the ions and vanishing magnetic field.
Stability of Waves in Relativistic Plasma
Authors: Gupta R. M. , Varma N. L. 
Published: July 2007

AbstractThe dispersion relation of electromagnetic waves propagating perpendicular to an applied uniform magnetic field B0 in relativistic plasma is derived. Waves propagating perpendicular to the uniform applied magnetic field can be separated into two modes ‐ one is the linearly polarized transverse wave and the other is a hybrid mode. In the present analysis, dispersion relation of the first mode i. e., for a pure transverse wave is analysed under the assumption that the wavelength is much longer than the cyclotron radii of the electrons. A stability criterion which limits the thermal energy of the electrons along B0 is obtained.
Über stationäre, rotierende, inkompressible Plasmen mit minimalen inneren Verlusten
Authors: Schäfer D. 
Published: July 2007

AbstractDie Forderung, daß nicht nur die Ohmschen, sondern auch die Verluste durch innere Reibung minimalisiert werden sollen, führt zu dem Ansatz, daß sowohl das Magnetfeld H als auch das Geschwindigkeitsfeld v Trkal‐Felder sind:

equation image

mit konstantem α, β. Im rotationssymmetrischen, stationären Fall folgt aus der Bedingung, daß die zum Rand senkrechte Komponente von v, v ⊥ und die toroidale Komponente vφ bzw. H⊥ und Hφ auf dem Rand verschwinden, ein lineares Eigenwertproblem für α, β, das sich insbesondere für rechteckige Grundbereiche leicht lösen läßt.Es ergibt sich:

equation image
.
Zur Theorie der parametrischen Anregung von elektrostatischen Oberflächenwellen in einer Plasmaschicht
Authors: Aliew Ju. M. , Gradow O. M. , Sünder D. 
Published: July 2007

AbstractDispersion relations for electrostatic surface waves in a homogeneous plasma‐layer which interacts with an external electric pumping field parallel to the boundaries are derived in the framework of the kinetic theory. The parametrically excited and purely growing instabilities are investigated. Electric threshold fields and growth rates for the instable surface modes are given. It can be shown that the minimum threshold for parametric excitation occurs for those modes which are symmetric about the midplane of the layer.
Anomales Verhalten des Säulenplasmas von Edelgasentladungen im longitudinalen Magnetfeld
Authors: Deutsch H. , Pfau S. 
Published: July 2007

AbstractEs wurden systematische Messungen der axialen elektrischen Feldstärke im Plasma der positiven Säule stromschwacher Entladungen in den Edelgasen Helium, Neon, Argon und Krypton in Abhängigkeit vom longitudinalen Magnetfeld durchgeführt. Überraschenderweise zeigen die erhaltenen Ergebnisse, daß der Säulengradient mit wachsendem Magnetfeld zunächst ansteigt, um erst nach dem Durchlaufen eines flachen Maximums abzusinken. Dieses im Gegensatz zu den Aussagen der klassischen Diffusionstheorie des Säulenplasmas im Magnetfeld stehende Verhalten konnte in allen Edelgasen beobachtet werden. Die charakteristischen Werte der magnetischen Induktion Bm/p0 für das Maximum hängen nur schwach von den Entladungsparametern ab und betragen für Helium 300 G/Torr, für Neon 500 G/Torr, für Argon 1000 G/Torr und für Krypton etwa 1500 G/Torr. Als Ursache für das Auftreten des Maximums im Gradienten wird die radiale Änderung der Energie‐verteilung der Elektronen in Abhängigkeit vom longitudinalen Magnetfeld angesehen.
A New Model of Crater Formation by Arc Spots
Authors: Hantzsche E. 
Published: July 2007

AbstractThe forces acting on the cathode arc spot surface and removing the molten layer from the crater bottom are composed mainly of the ion pressure, the neutral gas pressure and the evaporation recoil whilst electrostatic forces diminish the effective pressure that is in the order of some 109 dyn/cm2. The motion of the liquid layer caused by these forces is treated with the hydrodynamic equations. A simple solution exists in the special case of constant layer depth, that is achieved a few nanoseconds after spot formation. From this model the layer depths (some 0.1 μm) and the ejection velocities at the crater rims (few 104 cm/s) are calculated. The real spot velocity agrees with the velocity of the melting front below the spot surface, but because of the stochastic character of the spot motion the apparent velocity decreases with growing observation time intervals Δt according to Δt−1/2.
Non Equilibrium Vibrational Population and Dissociation Rates of Oxygen in Electrical Discharges: The Role of Atoms and of the Recombination Process
Authors: Cacciatore M. , Capitelli M. , Dilonardo M. 
Published: July 2007

AbstractThe influence of oxygen atoms on the population densities of vibrational levels of molecular oxygen has been studied for discharge conditions in which the atoms come 1) from electronic transitions to Herzberg and Schumann systems 2) from the pure vibrational mechanism (PVM) discussed in Chem. Phys. 30 (1978) 95.In the first case the atoms deactivate the first vibrational levels of O2, thus reducing the vibrational temperature and the propagation of the introduced vibrational quanta by V — V exchanges.Under these conditions PVM disappears. An assisted recombination dissociation mechanism, however, holds in these conditions, due to the recombination process which induces a strong disequilibrium on the levels near to the dissociation continuum. These levels can redissociate by collisions with heavy particles.The results of pure vibrational mechanism in the presence of atoms are very similar to those discussed in our previous work. The production of oxygen atoms self adjusts to small values due to the increased importance of V — T deactivation by oxygen atoms.