Statistical theory of the atom in momentum space

In 1992, Englert [Phys. Rev. A, 45;127--134] found a momentum energy functional for atoms and discussed the relation to the Thomas-Fermi functional (Lenz [Z. Phys., 77;713--721]). We place this model in a mathematical setting. Our results include a proof of existence and uniqueness of a minimizing momentum density for this momentum energy functional. Further, we investigate some properties of this minimizer, among them the connection with Euler's equation. We relate the minimizers of the Thomas-Fermi functional and the momentum energy functional found by Englert by explicit transforms. It turns out that in this way results well-known in the Thomas-Fermi model can be transferred directly to the model under consideration. In fact, we gain equivalence of the two functionals upon minimization. Finally, we consider momentum dependent perturbations. In particular, we show that the atomic momentum density converges to the minimizer of the momentum energy functional as the total nuclear charge becomes large in a certain sense. This thesis is based on joint work with Prof. Dr. Heinz Siedentop and the main contents will also appear in a joint article

Experimental insight into the magnetic and electrical properties of amorphous Ge1-xMnx

We present a study of the electrical and magnetic properties of the amorphous Ge1-xMnx.DMS, with 2% ≤ x ≤ 17%, by means of SQUID magnetometry and low temperature DC measurements. The thin films were grown by physical vapour deposition at 50°C in ultrahigh vacuum. The DC electrical characterizations show that variable range hopping is the main mechanism of charge transport below room temperature. Magnetic characterization reveals that a unique and smooth magnetic transition is present in our samples, which can be attributed to ferromagnetic percolation of bound magnetic polarons

Can the FUT2 non-secretor phenotype associated with gut microbiota increase the children susceptibility for type 1 diabetes? A mini review

The global toll of type 1 diabetes (T1D) has steadily increased over the last decades. It is now widely acknowledged that T1D pathophysiology is more complex than expected. Indeed, a multifaceted interplay between genetic, metabolic, inflammatory and environmental factors exists that leads to heterogeneous clinical manifestations across individuals. Children with non-secretor phenotype and those affected by T1D share low abundance of bifidobacteria, low content of short-chain fatty acids, intestinal phosphatase alkaline and a high incidence of inflammatory bowel diseases. In this context, host-gut microbiota dyad may represent a relevant contributor to T1D development and progression due to its crucial role in shaping host immunity and susceptibility to autoimmune conditions. The FUT2 gene is responsible for the composition and functional properties of glycans in mucosal tissues and bodily secretions, including human milk. FUT2 polymorphisms may profoundly influence gut microbiota composition and host susceptibility to viral infections and chronic inflammatory disease. In this minireview, the possible interplay between mothers’phenotype, host FUT2 genetic background and gut microbiota composition will be discussed in perspective of the T1D onset. The study of FUT2-gut microbiota interaction may add a new piece on the puzzling T1D etiology and unveil novel targets of intervention to contrast T1D development and progression. Dietary interventions, including the intake of a-(1, 2)-fucosyl oligosaccharides in formula milk and the use of specific prebiotics and probiotics, could be hypothesized

Statistical theory of the atom in momentum space

In 1992, Englert [Phys. Rev. A, 45;127--134] found a momentum energy functional for atoms and discussed the relation to the Thomas-Fermi functional (Lenz [Z. Phys., 77;713--721]). We place this model in a mathematical setting. Our results include a proof of existence and uniqueness of a minimizing momentum density for this momentum energy functional. Further, we investigate some properties of this minimizer, among them the connection with Euler's equation. We relate the minimizers of the Thomas-Fermi functional and the momentum energy functional found by Englert by explicit transforms. It turns out that in this way results well-known in the Thomas-Fermi model can be transferred directly to the model under consideration. In fact, we gain equivalence of the two functionals upon minimization. Finally, we consider momentum dependent perturbations. In particular, we show that the atomic momentum density converges to the minimizer of the momentum energy functional as the total nuclear charge becomes large in a certain sense. This thesis is based on joint work with Prof. Dr. Heinz Siedentop and the main contents will also appear in a joint article

Growth of room temperature ferromagnetic Ge1-xMnx quantum dots on hydrogen passivated Si (100) surfaces

A method for the synthesis of room-temperature ferromagnetic dilute semiconductor Ge1-xMnx (5 % < x < 8 %) quantum dots by molecular beam epitaxy by selective growth on hydrogen terminated silicon (100) surface is presented. The functionalized substrates, as well as the nanostructures, were characterized in situ by reflection high-energy electron diffraction. The quantum dots density and equivalent radius were extracted from field emission scanning electron microscope pictures, obtained ex-situ. Magnetic characterizations were performed by superconducting quantum interference device vibrating sample magnetometry revealing that ferromagnetic order is maintained up to room temperature: two different ferromagnetic phases were identified by the analysis of the field cooled – zero field cooled measurements

A 2 GHz Bandpass Analog to Digital Delta-sigma Modulator for CDMA Receivers with 79 DB Dynamic Range in 1.23 MHz Bandwidth

This paper presents the design of a second-order single-bit analog-to-digital continuous-time delta-sigma modulator that can be used in wireless CDMA receivers. The continuous-time delta-sigma modulator samples at 2 GHz, consumes 18 mW at 1.8 V and has a 79-dB signal-to-noise ratio (SNR) over a 1.23-MHz bandwidth. The continuous-time delta-sigma modulator was fabricated in a 0.18- m 1-poly 6-metal, CMOS technology and has an active area of approximately 0.892 mm2 . The delta-sigma modulator\u27s critical performance specifications are derived from the CDMA receiver specifications

Niveles de representación sobre estructura de la materia y fenómenos asociados en estudiantes de séptimo de la institución educativa gabriela mistral.

En este trabajo de investigación se busca sistematizar una experiencia de aula en la cual se indagan las representaciones sobre la estructura de la materia y fenómenos asociados que tienen los estudiantes del grado séptimo de la Institución Educativa (IE) Gabriela Mistral que se encuentra ubicada en el departamento de Caquetá municipio de Belén de los Andaquíes. La estructura de materia, como concepto estructural de la química, se encuentra en la malla curricular del área de ciencias naturales desde el grado sexto y se va profundizando (complejizando) en los siguientes grados de la educación secundaria. El aprendizaje de este concepto exige la interacción de los diferentes niveles de representación de la química: macroscópico, microscópico y simbólico. Se propone la aplicación de un instrumento, para el diagnóstico (ID) de los niveles de representación de los estudiantes, como activada para indagar las ideas previas (IP) de los estudiantes sobre este tema específico como punto de partida para el diseño de una unidad didáctica (UD) sobre la estructura de la materia y fenómenos asociados donde se trabaja: partículas subatómicas y los modelos atómicos. Como una actividad de evaluación de los aprendizajes se aplica el instrumento diagnostico para evidenciar posibles cambios en las representaciones sobre la estructura de la materia y fenómenos asociados. El objetivo de este trabajo, entre otros, es el de sistematizar la experiencia de aula, como una forma de cualificar la práctica del docente-investigador, aportar al proceso de aprendizajes de los estudiantes, y finalmente se busca que este trabajo sirva de referente para las prácticas de otros integrantes de la comunidad educativa, como también aportar al campo de la didáctica de las ciencias naturales-química.This research work seeks to systematize a classroom experience in which are investigated the representations about the structure of the subject that students of the seventh grade of the Educational Institution (IE) Gabriela Mistral which is located in the department of Caquetá, municipality of Belén de los Andaquíes. The structure of matter, as a structural concept of chemistry, is found in the curriculum of the natural sciences area from the sixth grade and it deepens (becomes more complex) in the following grades of secondary education. Learning this concept requires the interaction of the different levels of representation of chemistry: macroscopic, microscopic, and symbolic. The application of an instrument is proposed, for the diagnosis (ID) of the levels of representation of the students, as activated to investigate the previous ideas (IP) of the students on this specific topic as a starting point for the design of a unit didactics (UD) on the structure of matter where you work: subatomic particles and atomic models. As a learning evaluation activity, the diagnostic instrument is applied to show possible changes in the representations about the structure of the matter. The objective of this work, among others, is to systematize the classroom experience, to qualify the practice of the teacher-researcher, contribute to the learning process of the students, and finally it is sought that this work serves as a reference for the practices of other members of the educational community, as well as contributing to the field of natural science-chemistry didactics

Gruppo elettrovalvola perfezionata per impianti fluidici di condizionamento e relativo gruppo contabilizzatore

Un gruppo servovalvola definente un condotto collegabile ad una linea di un impianto termoidraulico tramite mezzi di collegamento filettati rilasciabili, comprende un dispositivo a turbina alloggiato nel condotto, una prima pluralità di magneti permanenti portati da un rotore del dispositivo a turbina, una seconda pluralità di poli magnetici accoppiati magneticamente alla prima pluralità di magneti permanenti, una centralina di controllo collegata ai poli magnetici, una batteria collegata alla centralina di controllo per essere caricata tramite il dispositivo a turbina, un trasmettitore collegato alla centralina di controllo per trasmettere / ricevere dati a distanza, un attuatore di regolazione fluidica configurato per regolare il flusso nel condotto e controllato / alimentato tramite la centralina di controllo e la batteri

A flow SPR immunosensor based on a sandwich direct method

In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10-3 and 10-1 M, a measurement time of ≤20 min and a high selectivity both towardsβ-lactam antibiotics and antibiotics of different classes. © 2016 by the author