Scattering cancellation of the magnetic dipole field from macroscopic spheres

Based on the scattering cancellation technique we suggest a cloak that allows to conceal macroscopic objects, i.e. objects with an optical size comparable to wavelengths in the visible and whose scattering response is dominated by a magnetic dipole contribution. The key idea in our approach is to use a shell of polaritonic spheres around the object to be cloaked. These spheres exhibit an artificial magnetism. In a systematic investigation, where we progressively increase the complexity of the considered structure, we devise the requirements imposed on the shell and outline how it can be implemented with natural available materials

A bottom-up approach to fabricate optical metamaterials by self-assembled metallic nanoparticles

We introduce a novel bottom-up approach to fabricate by self assembly a metamaterial from metallic nanoparticles in a two-step process. In the first step, a metamaterial made of densely packed silver nanoparticles is required. The material dispersion with increasing nanoparticle densities, from dispersed to randomly packed nanoparticles, was measured by spectroscopic ellipsometry, demonstrating high permittivity values in the visible. In the second step, this material was used to prepare spherical clusters by a method based on oil-in-water emulsion. The optical properties of these clusters were equally investigated by spectroscopic means. Comparisons with rigorous numerical simulations clearly indicate that, depending on the cluster size, their spectral response can be unambiguously associated with the excitation of a magnetic dipole resonance. As a consequence, such spherical clusters are promising building blocks for future metamaterials possessing a magnetic response in the visible range

Studie zum aktiven und passiven Wahlrecht von Menschen mit Behinderung

Die Studie beschäftigt sich mit den Voraussetzungen und Grenzen der in § 13 Nr. 2 und 3 Bundeswahlgesetz (BWG) geregelten Wahlrechtsausschlüsse. Sie betreffen Menschen, für die zur Besorgung aller ihrer Angelegenheiten ein Betreuer nicht nur durch einstweilige Anordnung bestellt ist (Nr.2) sowie Menschen, die sich auf Grund einer Anordnung nach § 63 in Verbindung mit § 20 des Strafgesetzbuches in einem psychiatrischen Krankenhaus befinden (Nr. 3). Die Untersuchung verfolgt einen interdisziplinären Ansatz. In ihrem sozialwissenschaftlichen Teil erfolgen empirische Erhebungen über die Anzahl der bundesweit von den genannten Wahlrechtsausschlüssen Betroffenen, deren soziodemographische Merkmale sowie der den Ausschlüssen zugrundeliegenden Krankheitsbildern. Außerdem werden im klinisch-psychologischen Teil die Betroffenenperspektive einbezogen, bestehende und mögliche Assistenzsysteme auch im internationalen Vergleich skizziert und der objektivierbare Bedarf nach Assistenz und die subjektiven Bedürfnisse hinsichtlich derartiger Unterstützungs-und Assistenzmaßnahmen dargestellt. In den juristischen Teilen erfolgt eine Untersuchung der Wahlrechtsausschlüsse in völkerrechtlicher und - damit in Wechselbeziehung stehend - verfassungsrechtlicher Perspektive. Im Mittelpunkt der völkerrechtlichen Untersuchung stehen die Vorgaben durch die Behindertenrechtskonvention (BRK). Deren Vorschriften werden nach den Regeln der Auslegung völkerrechtlicher Verträge interpretiert und im Kontext der Meinung des BRK-Ausschusses sowie der politischen Dynamik in der internationalen Gemeinschaft diskutiert. Im Zentrum des verfassungsrechtlichen Teils der Studie steht zunächst die verfassungsrechtliche Maßstabsentfaltung und hier namentlich das Zusammenspiel der verfassungsrechtlichen Wahlrechtsgrundsätze mit den spezifischen Benachteiligungsverboten von Menschen mit Behinderungen sowie der Bedeutung der BRK. § 13 Nr. 2 und 3 BWG werden sodann an diesem Maßstab überprüft. Abschließend zeigt die Studie 4 Handlungsoptionen auf.The study deals with the prerequisites and the limits of the disenfranchisement regulated in Section 3 No. 2 and 3 Federal Electoral Act. These provisions concern persons on whose behalf a custodian has been appointed to attend to all his or her affairs (No. 2) as well as persons who are accommodated in a psychiatric hospital under an order pursuant to Section 63 of the Penal Code in conjunction with Section 20 of the Penal Code. The study employs an interdisciplinary approach. In the sections of the social science analysis, an empirical survey concerning the number of persons affected in Germany by such disenfranchisement as mentioned above has been made, their sociodemographic attributes as well as the clinical situation under-pinning their disenfranchisement. In addition, the clinical-psychological section of the study describes the existing as well as alternative assistance systems employed internationally and illustrates the individual needs for assistance. The social-science sections are followed by two legal considerations, examining the current German disenfranchisement provisions from both an international and constitutional law perspective, the latter of which is mindful of international law. At the centre of the public international law section stands the International Convention on the Rights of Persons with Disabilities (CRPD). The provisions of this treaty are interpreted in accordance with the customary international rules of treaty interpretation and the result is discussed in the light of the opinion of the CRPD Committee and the political dynamics of the international community. The focus of the section dealing with the German Constitution is based on relevant constitutional standards and principles, especially the interplay between constitutional electoral principle with specific constitutional law on discrimination against people with disabilities as well as similar international law provisions. Section 13 No. 2 and 3 Federal Electoral Act is examined in the light of the constitutional benchmark established. Following on from a comparative law section, the study presents possible options for legislative action

Gouy phase anomaly in photonic nanojets

We investigate in real space amplitude and phase distributions of light in photonic nanojets emerging from micrometer-sized dielectric spheres with a high-resolution interference microscope. Strong localization of light and a Gouy phase anomaly are witnessed. We show that the phase advance of photonic nanojets significantly deviates from a plane wave due to the sudden transition from a converging to a diverging wave front. Understanding such phase anomalies and verifying the presence of photonic nanojets promises to pave the way to prospective applications that may exploit the ability to localize light in spatial domains smaller than the usual resolution limit

Podocytes Produce and Secrete Functional Complement C3 and Complement Factor H

Podocytes are an important part of the glomerular filtration barrier and the key player in the development of proteinuria, which is an early feature of complement mediated renal diseases. Complement factors are mainly liver-born and present in circulation. Nevertheless, there is a growing body of evidence for additional sites of complement protein synthesis, including various cell types in the kidney. We hypothesized that podocytes are able to produce complement components and contribute to the local balance of complement activation and regulation. To investigate the relevant balance between inhibiting and activating sides, our studies focused on complement factor H (CFH), an important complement regulator, and on C3, the early key component for complement activation. We characterized human cultured podocytes for the expression and secretion of activating and regulating complement factors, and analyzed the secretion pathway and functional activity. We studied glomerular CFH and C3 expression in puromycin aminonucleoside (PAN) -treated rats, a model for proteinuria, and the physiological mRNA-expression of both factors in murine kidneys. We found, that C3 and CFH were expressed in cultured podocytes and expression levels differed from those in cultivated glomerular endothelial cells. The process of secretion in podocytes was stimulated with interferon gamma and located in the Golgi apparatus. Cultured podocytes could initiate the complement cascade by the splitting of C3, which can be shown by the generation of C3a, a functional C3 split product. C3 contributed to external complement activation. Podocyte-secreted CFH, in conjunction with factor I, was able to split C3b. Podocytes derived from a patient with a CFH mutation displayed impaired cell surface complement regulation. CFH and C3 were synthesized in podocytes of healthy C57Bl/6-mice and were upregulated in podocytes of PAN treated rats. These data show that podocytes produce functionally active complement components, and could therefore influence the local glomerular complement activation and regulation. This modulating effect should therefore be considered in all diseases where glomerular complement activation occurs. Furthermore, our data indicate a potential novel role of podocytes in the innate immune system

Refraction limit of miniaturized optical systems: A ball-lens example

We study experimentally and theoretically the electromagnetic field in amplitude and phase behind ball-lenses across a wide range of diameters, ranging from a millimeter scale down to a micrometer. Based on the observation, we study the transition between the refraction and diffraction regime. The former regime is dominated by observables for which it is sufficient to use a ray-optical picture for an explanation, e.g., a cusp catastrophe and caustics. A wave-optical picture, i.e. Mie theory, is required to explain the features, e.g., photonic nanojets, in the latter regime. The vanishing of the cusp catastrophe and the emergence of the photonic nanojet is here understood as the refraction limit. Three different criteria are used to identify the limit: focal length, spot size, and amount of cross-polarization generated in the scattering process. We identify at a wavelength of 642 nm and while considering ordinary glass as the ball-lens material, a diameter of approximately 10 µm as the refraction limit. With our study, we shed new light on the means necessary to describe micro-optical system. This is useful when designing optical devices for imaging or illumination

Large-scale analysis of Drosophila core promoter function using synthetic promoters

The core promoter plays a central role in setting metazoan gene expression levels, but how exactly it “computes” expression remains poorly understood. To dissect its function, we carried out a comprehensive structure–function analysis in Drosophila. First, we performed a genome-wide bioinformatic analysis, providing an improved picture of the sequence motifs architecture. We then measured synthetic promoters’ activities of ~3,000 mutational variants with and without an external stimulus (hormonal activation), at large scale and with high accuracy using robotics and a dual luciferase reporter assay. We observed a strong impact on activity of the different types of mutations, including knockout of individual sequence motifs and motif combinations, variations of motif strength, nucleosome positioning, and flanking sequences. A linear combination of the individual motif features largely accounts for the combinatorial effects on core promoter activity. These findings shed new light on the quantitative assessment of gene expression in metazoans