Parameterizations of sub-attractors in hyperbolic balance laws

This article investigates the properties of the global attractor of hyperbolic balance laws on the circle, given by : u_t+f(u)_x=g(u). The new tool of sub-attractors is introduced. They contain all solutions on the global attractor up to a given number of zeros. The article proves finite dimensionality of all sub-attractors, provides a full parameterization of all sub-attractors and derives a system of ODEs for the embedding parameters that describes the full PDE dynamics on the sub-attractor

Slow motion of quasi-stationary multi-pulse solutions by semistrong interaction in reaction-diffusion systems

In this paper, we study a class of singularly perturbed reaction-diffusion systems, which exhibit under certain conditions slowly varying multi-pulse solutions. This class contains among others the Gray-Scott and several versions of the Gierer-Meinhardt model. We first use a classical singular perturbation approach for the stationary problem and determine in this way a manifold of quasi-stationary $N$-pulse solutions. Then, in the context of the time-dependent problem, we derive an equation for the leading order approximation of the slow motion along this manifold. We apply this technique to study 1-pulse and 2-pulse solutions for classical and modified Gierer-Meinhardt system. In particular, we are able to treat different types of boundary conditions, calculate folds of the slow manifold, leading to slow-fast motion, and to identify symmetry breaking singularities in the manifold of 2-pulse solutions

UV light induced photoreduction in phosphate and fluoridephosphate glasses doped with Ni2+, Ta5+, Pb2+, and Ag+ compounds

The photoreduction of polyvalent ions was studied in high purity fluoride-phosphate and metaphosphate glasses doped with Ni2+ (3d8), Ta5+ (5d0), Pb2+ (6d2), and Ag+ (3d10). Compared to the undoped base glasses all doped samples display different electronic transitions in the UV at the irradiation wavelength. Glass samples containing 50 to 5000 ppm dopants were irradiated with excimer lasers at 193 and 248 nm, respectively. The subsequent defect centers, formed at ppm levels, were characterized by EPR and optical UV-VIS spectroscopy. The observed laser induced transmission losses in the UV and visible range increased in the order Ni, Ta, Pb to Ag. Extrinsic electron centers are formed by photoreduction of the dopants. (Ni2+)- is characterized by an optical transition with a maximum at 355 nm and an EPR signal around g ≈ 2.07. The maxima of the optical transitions of the (Pb2+)- -EC are positioned at 395 and 500 nm, of the (Ta5+)- -EC at 465 nm. The photoionization products of silver depend strongly on the silver concentration. At a silver content of 50 ppm only the (Ag+)- -EC is formed, visible in the optical spectra with a maximum around 450 nm. Α second silver species, (Ag+)2 -, which absorbs at 305 nm, is additionally observed in the sample doped with a silver concentration of 500 ppm. In the sample doped with 5000 ppm silver a third defect, the photooxidized (Ag+)+ -HC, with an optical band maximum at 405 nm and an EPR signal around g ≈ 2.3 is observed as well. The formation of extrinsic electron centers causes in all glasses an increase in the formation of intrinsic hole centers and often a decrease in the formation of intrinsic electron centers. Defect generation curves show that a very rapid darkening in the glasses is initiated by the addition of any of these dopants. The recovery rates of the defeets formed depend strongly on the dopant, not on the glass matrix

Slow motion of quasi-stationary multi-pulse solutions by semistrong interaction in reaction-diffusion systems

In this paper, we study a class of singularly perturbed reaction-diffusion systems, which exhibit under certain conditions slowly varying multi-pulse solutions. This class contains among others the Gray-Scott and several versions of the Gierer-Meinhardt model. We first use a classical singular perturbation approach for the stationary problem and determine in this way a manifold of quasi-stationary $N$-pulse solutions. Then, in the context of the time-dependent problem, we derive an equation for the leading order approximation of the slow motion along this manifold. We apply this technique to study 1-pulse and 2-pulse solutions for classical and modified Gierer-Meinhardt system. In particular, we are able to treat different types of boundary conditions, calculate folds of the slow manifold, leading to slow-fast motion, and to identify symmetry breaking singularities in the manifold of 2-pulse solutions

Irradiation-induced defects in different glasses demonstrated on a metaphosphate glass

The influence of the two polyvalent ions, cobalt and nickel, on the formation of irradiation-induced defects was studied in several different model glasses (silicate, borosilicate, fluoride- and phosphate glasses). In this article the defects are demonstrated on the example of the (SrPO3)2-metaphosphate glass P100. Sample plates of high-purity glasses, undoped and doped with 0.3 mol% CoO and NiO, were irradiated with a UV lamp and with X-rays. The subsequent defect centers, formed at ppm levels, were characterized by EPR as well as optical UV-VIS spectroscopy. Defect recovery experiments were also studied in these glasses. The newly found optical bands and EPR signals evolving in the irradiated glass are in part characteristic for intrinsic defects. These are different types of electron centers (EC) and hole centers (HC) connected with phosphate groups. Other signals arise from extrinsic defects, which are caused by the two dopant ions. The predominant extrinsic defect stems from the photooxidation of Co2+ to (Co2+)2. As an HC the latter replaces some of the intrinsie phosphate-bonded HC and dominates the optical spectra with two bands at 300 and 400 nm. In the glass P100 lamp irradiation photoionizes only Co2+ but not Ni2+. Α new optical band at 330 nm, as well as a new EPR signal at g = 2.08 can be seen only after X-ray irradiadon. Both can be attributed to a nickel-related EC created via the photoreduction of Ni2+ to (Ni2+)-. At the same time the band of the intrinsic oxygen-related HC is intensified. Generally X-ray irradiation causes stronger irradiation-induced defects (excitation of inner electrons) than UV-lamp irradiation (selective excitation of valence electrons)

Influence of melting and annealing conditions on the optical spectra of a borosilicate glass doped with CoO and NiO

In the high-viscosity borosilicate glass (NBS2) doped with 0.3 mol% CoO or NiO quenching resulted in a freeze-in snap-shot of the glass structure within the dopants' transformation process from their high-temperature tetrahedral coordination to the octahedral form normally present in this glass at room temperature. In this transitional state the octahedral, tetrahedral and a third pseudotetrahedral transitional coordination are simultaneously present. The optical spectra of the doped glasses are discussed in relation to the different melting and cooling conditions applied. Quenched glasses were also tempered on a heating table, which permitted to take the optical spectra at each temperature step. In contrast to Co2+, Ni2+ has a strong octahedral preference. Thus for NiO-doped NBS2 glass tempering or annealing always results in relaxation into the octahedral coordination. For Co2+, which is also octahedrally coordinated in the annealed NBS2, tempering of the quenched glass leads to a relaxation into octahedrally and tetrahedrally coordinated Co2+. These structural changes are especially strong when the applied temperatures lie 150 to 200 °C above Tg of the NBS2 glass where also the viscosity-temperature curve implies structural changes within the glass matrix

Gender identity and expression in focus: The report of the United Nations Independent Expert on sexual orientation and gender identity, by Victor Madrigal-Borloz.: Published by the United Nations on 12/07/2018 United Nations official document number: A/73/152

In his recent report, the United Nations Independent Expert on protection against violence and discrimination based on sexual orientation and gender identity, Victor Madrigal-Borloz, examines the “process of abandoning the classification of certain forms of gender as a pathology” – “depathologization”—and elaborates on the “full scope of the duty of the State to respect and promote respect of gender recognition as a component of identity” (p. 2). The report also discusses active measures to respect gender identity and concludes with a list of recommendations. While other United Nations special procedures and agencies have addressed and condemned violence and discrimination on the grounds of gender identity and expression, this report provides a deeper analysis on its root causes. It is the first special procedures report that exclusively addresses human rights with regard to gender identity and expression, and must be considered a mile-stone in the development and enunciation of international human rights law in this regard

Formation of radiation defects in Silicate and borosilicate glasses caused by UV lamp and excimer laser Irradiation

Solarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transmission in the UV-B region (280 to 320 nm) was investigated for their use as Container glasses in the solar disinfection of drinking water. The samples were coloured by doping with NiO or CoO. The influence of the Fe³⁺/Fe²⁺ content and of the reducing component Sn²⁺ was investigated on both the initial transmission of the glasses and the solarizadon. The samples were irradiated with a 1 kW Xe lamp and a XeCl excimer laser. The solarization depends on the glass matrix and is enhanced by colouring ions. The influence of Fe³⁺/Fe²⁺ and Sn²⁺ on the defect generation is different for glasses coloured with NiO than for those coloured with CoO. For the samples investigated it was possible to simulate the loss of transmission in the UV-B region due to long-time irradiation with sunlight by a laser experiment

Time resolved fluorescence measurements on Tb3+ and Mn2+ doped glasses

Tb3+ (4f8) and Mn2+ (3d5) ions, known as active luminescent centres for blue, green and red fluorescence, were doped in various fluoride, phosphate and Silicate glasses with well known structure. Narrow bands of f-f transitions with strong emission of Tb3+ in the blue, green and red and broad bands of d-d transitions of Mn2+ were measured with green emission in high optical basicity glasses with tetrahedrally coordinated Mn2+. Orange to red Mn2+ emission was found in glasses with low optical basicity where Mn2+ is octahedrally coordinated. Lifetimes, τe, in the range of milliseconds were recorded in dependence of glass composition and dopant concentration for both Tb3+ and Mn2+ doped glasses. Fluorescence lifetimes are as well shortened by higher basicity of the glasses as by increasing dopant concentration