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Microlensing results from APO monitoring of the double quasar Q0957+561A,B between 1995 and 1998
(2000)
If the halo of the lensing galaxy 0957+561 is made of massive compact objects (MACHOs), they must affect the lightcurves of the quasar images Q0957+561 A and B differently. We search for this microlensing effect in the double quasar by comparing monitoring data for the two images A and B - obtained with the 3.5m Apache Point Observatory from 1995 to 1998 - with intensive numerical simulations. This way we test whether the halo of the lensing galaxy can be made of MACHOs of various masses. We can exclude a halo entirely made out of MACHOs with masses between 10-6 Msun and 10-2 Msun for quasar sizes of less than 3x 1014 h60-1/2 cm, hereby extending previous limits upwards by one order of magnitude.
Menschenrechte
(2000)
Das erste umfassende deutschsprachige Lexikon über die Vereinten Nationen enthält einen menschenrechtlichen Schwerpunktteil. Dieser Beitrag gibt eine grundlegende Einführung in die geistesgeschichtliche Entwicklung der Menschenrechte. Außerdem erläutert er in geraffter Form die Normierung von Menschenrechten auf der universellen Ebene. Abschließend werden verschiedene, häufig diskutierte Problemfelder behandelt. Hierzu zählen Fragen der Universalität von Menschenrechten, das Recht auf Entwicklung und die Durchsetzung und Förderung von Menschenrechten.
Nach einleitenden Ausführungen über die Maßnahmen zum Schutz von Frauenrechten im Rahmen der Vereinten Nationen insgesamt konzentriert sich der Beitrag auf die Darstellung des Übereinkommens zur Beseitigung jeder Form von Diskriminierung der Frau (CEDAW). Dessen materielle Gewährleistungen werden erläutert und der zugehörige Überwachungsmechanismus vorgestellt. Ein abschließender Ausblick stellt die Neuerungen dar, die mit den Individualbeschwerdeverfahren verbunden sein werden, die durch das inzwischen in Kraft getretene Zusatzprotokoll zu erwarten sind.
Dieser in der Grundschule erprobte Multimedia-Baustein für die ökologische Grundbildung versteht sich als Beitrag zur Entwicklung einer innovativen Lernkultur (Nutzung von Computer, Multimedia und Internet in schulischen Lern- und Lehrkontexten) und als Beitrag für die Verbindung von Begegnung mit Originalen und dem Lernen mit modernen Medien und dem Internet das Finden eines optimalen Verhältnisses zwischen selbst gesteuertem Lernen und pädagogisch intendierten Strukturierungen (z.B. in multimedialen Lernumgebungen) die Förderung und Entwicklung komplexen (System-)Denkens und Überwindung monokausalen Denkens sowie die Entwicklung eines modellhaften Ansätzes (animierende und initiierende Wirkung) für fächerübergreifendes, integratives Lernen unter Nutzung moderner Medien (vor allem Multimedia, weil per se integrativ)
Elektronische Struktur niedrigdimensionaler Systeme auf Oberflächen mit zweizähliger Symmetrie
(2000)
Kinetic analysis of the thermic effect of food and its relationship to body composition in humans
(2000)
The course of energy expenditure after a meal can vary widely with regard to the slope of onset, amplitude, and duration of the thermic effect. The aim of the present study was to explore the relationship between the thermic effect of food (TEF), as characterized by kinetic analysis of postprandial energy expenditure, body composition, and variables related to the metabolic syndrome including central obesity, hypertension, and glucose tolerance. A total of 181 men and women (body mass index [BMI] range, 19.4 to 52.2 kg/m2) were characterized for body composition, blood pressure, oral glucose tolerance, and energy expenditure after a test meal. Energy expenditure, as measured by indirect calorimetry, was analyzed over a 6-hour period by 3-parameter curve fitting using equations derived from kinetics describing a biphasic reaction involving 2 consecutive first-order reactions (A->B->C). Apart from total thermic effect of food (TEFk), the curve also provided an estimate of time of peak (Tp) and amplitude of peak (Ap) for each subject. Multiple stepwise regression analysis with TEFk, Ap, and Tp as dependent variables showed significant effects of sex, age, body weight, body fat, -blockade, and body composition on TEF curve parameters. Cluster analysis based on Tp shown 2 distinct clusters with significant differences in age and body fat mass. This study shows that kinetic analysis of postprandial energy expenditure can be used to examine the determinants of the time course of the thermic effect of food in man.
Eichfeldtheorie
(2000)
Editor's note to A. Sakharov
(2000)
Flux Tubes in Weyl Gravity
(2000)
Planeten um andere Sterne
(2000)
Requiem auf West-Berlin
(2000)
Rechtskraft bei Teilklagen
(2000)
Der Erwerb des frühkindlichen Lexikons : eine empirische Studie zur Entwicklung des Wortschatzes
(2000)
Gershom Scholem : Tagebücher nebst Aufsätzen und Entwürfen bis 1923 ; 2. Halbband 1917 - 1923
(2000)
Zitat
(2000)
New substituted 2,5-diphenyl-1,3,4-oxadiazoles are reported as luminescent materials in light emitting diodes LEDs . The investigated new oxadiazoles show efficient blue and green emission in single layer devices. The combination with a hole transporting and red emitting polythiophene led to a white emission with higher quantum efficiency (QE).
Neues Lexikon des Judentums
(2000)
Theoretischer Hintergrund: Zur Erforschung der Entwicklungsepidemiologie psychischer Störungen gilt die prospektive Untersuchung von Risikogruppen als Königsweg. Fragestellung: Beschreibung der Entwicklungsmuster von Kindern mit frühen Belastungen, Ermittlung von Risiko- und Schutzfaktoren für unterschiedliche Entwicklungsresultate und Identifikation von Mechanismen, die differentiellen Verläufen zugrunde liegen. Methode: In einer prospektiven Längsschnittstudie (mit Erhebungswellen im Alter von 0;3, 2, 4 , 8 und 11 Jahren) wurden die Entstehung und der Verlauf von Entwicklungs- und Verhaltensstörungen bei 384 Kindern untersucht. Organische (prä- und perinatale Komplikationen) und psychosoziale Risiken (familiäre Belastungen) wurden in einem zwei- faktoriellen Design variiert. Ergebnisse: Die negativen Folgen früher Risiken waren bis zum Schulalter nachweisbar. Während organische Risiken vor allem die motorische und kognitive Entwicklung beeinträchtigten, konzentrierten sich die Auswirkungen psychosozialer Belastungen auf kognitive und sozial-emotionale Funktionen. Beide Risiken addierten sich in ihren negativen Konsequenzen. Schlussfolgerungen: Frühkindliche Risiken haben spezifische und langfristige Auswirkungen. Kinder mit multiplen Risikobelastungen sind in ihrer Entwicklung am stärksten gefährdet.
Fachdidaktische Literatur
(2000)
Elite und Elitenbildung I : zu den Prinzipien von Auslese und Gleichheit im deutschen Spitzensport
(2000)
Auf der Schaukel : Jugend, Liebe und die Grenzen des Spiels in Italo Calvinos "Il barone rampante"
(2000)
Surface light emitting diodes SLEDs , in which previously microfabricated electrodes were coated with a conjugated polymer, were made with greatly different electrode spacings 250 nm and 10 or 20 mm and with different electrode material combinations. The fabrication process allowed us to compare several electrode materials. The SLED structures also enabled imaging of the light emission zone with fluorescence video microscopy. Conventional sandwich structures were also made for comparison electrode separation 50 nm. In this study, the emitting layer was poly[3- (2',5'-bis(1'',4'',7''trioxaoctyl)phenyl)-2,2'-bithiophene] (EO-PT), a conjugated polymer based on polythiophene with oligo ethyleneoxide side chains. The current-voltage (I(V)) and light-voltage (L(V)) characteristics of the SLEDs were largely insensitive to electrode separation except at high voltages, at which the current in the devices with the largest separations was limited. Sandwich structures had the same light output at a given current. Light could be obtained in forward and reverse bias from indium tin oxide ITO -aluminum, gold silicide-aluminum, and gold silicide-gold SLEDs, but the turn-on voltages were lowest with the ITO-aluminum devices, and these were also the brightest and most reliable. Adding salt to the EO-PT increased the current and brightness, decreased the turn-on voltages, and made the I(V) characteristics symmetric; thus, a device with an electrode separation of 10 mm had the extraordinarily low turn-on voltage of 6 V. The location of the light emission was at the electron-injecting contact.
Since 1993 the southern shore of Lake Gülpe in western Brandenburg has been man-aged with Galloway cattle. This is supported by the so called "Vertragsnaturschutz" (i.e. contract nature conservation) in order to preserve the valuable, species-rich vegetation structure. This is an economically justifiable arrangement for the Galloway cattle-farmer. Permanent botanical plots were monitored in the area for four years. For most species, the observed changes in vegetation are considered as mere fluctuations on the basis of their known ecological requirements and data on hydrological dynamics during the study. Only a few species might indicate succession. A continuation of the present form of land management is recommended for the preservation of the current vegetation structure. However it is advisable to continue with monitoring of the vegetation in order to confirm the results over larger timescales. Until then the management with Galloway cattle is to acclaim as a proper treatment to preserve the southern shore of Lake Gülpe.
The equilibrium states of electrically conducting fluids or plasmas have been a subject of intense study for a long time, motivated in particular by the interest in controlled thermonuclear fusion, as well as that in space and astrophysical phenomena such as plasma loops in the solar corona. If high temperatures prohibit solid walls, a conducting fluid can be held together by the action of an electric current passing through it with the pressure gradients being balanced by the Lorentz force. The resultant configuration is known as a pinch. In this paper we report on studies of the pinch in the geometry of a plane sheet.
The equilibrium states of electrically conducting fluids or plasmas have been a subject of intense study for a long time, motivated in particular by the interest in controlled thermonuclear fusion, as well as that in space and astrophysical phenomena such as plasma loops in the solar corona. If high temperatures prohibit solid walls, a conducting fluid can be held together by the action of an electric current passing through it with the pressure gradients being balanced by the Lorentz force. The resultant configuration is known as a pinch. In this paper we report on studies of the pinch in the geometry of a plane sheet.
A numerical bifurcation analysis of the electrically driven plane sheet pinch is presented. The electrical conductivity varies across the sheet such as to allow instability of the quiescent basic state at some critical Hartmann number. The most unstable perturbation is the two-dimensional tearing mode. Restricting the whole problem to two spatial dimensions, this mode is followed up to a time-asymptotic steady state, which proves to be sensitive to three- dimensional perturbations even close to the point where the primary instability sets in. A comprehensive three- dimensional stability analysis of the two-dimensional steady tearing-mode state is performed by varying parameters of the sheet pinch. The instability with respect to three-dimensional perturbations is suppressed by a sufficiently strong magnetic field in the invariant direction of the equilibrium. For a special choice of the system parameters, the unstably perturbed state is followed up in its nonlinear evolution and is found to approach a three-dimensional steady state.
We investigate numerically the appearance of heteroclinic behavior in a three-dimensional, buoyancy-driven fluid layer with stress-free top and bottom boundaries, a square horizontal periodicity with a small aspect ratio, and rotation at low to moderate rates about a vertical axis. The Prandtl number is 6.8. If the rotation is not too slow, the skewed-varicose instability leads from stationary rolls to a stationary mixed-mode solution, which in turn loses stability to a heteroclinic cycle formed by unstable roll states and connections between them. The unstable eigenvectors of these roll states are also of the skewed-varicose or mixed-mode type and in some parameter regions skewed-varicose like shearing oscillations as well as square patterns are involved in the cycle. Always present weak noise leads to irregular horizontal translations of the convection pattern and makes the dynamics chaotic, which is verified by calculating Lyapunov exponents. In the nonrotating case the primary rolls lose, depending on the aspect ratio, stability to traveling waves or a stationary square pattern. We also study the symmetries of the solutions at the intermittent fixed points in the heteroclinic cycle.