Quark Potential in a Quark-Meson Plasma

We investigate quark potential by considering meson exchanges in the two flavor Nambu--Jona-Lasinio model at finite temperature and density. There are two kinds of oscillations in the chiral restoration phase, one is the Friedel oscillation due to the sharp quark Fermi surface at high density, and the other is the Yukawa oscillation driven by the complex meson poles at high temperature. The quark-meson plasma is strongly coupled in the temperature region $1\le T/T_c \lesssim 3$ with $T_c$ being the critical temperature of chiral phase transition. The maximum coupling in this region is located at the critical point.Comment: 8 pages and 8 figure

Transport-theoretical Description of Nuclear Reactions

In this review we first outline the basics of transport theory and its recent generalization to off-shell transport. We then present in some detail the main ingredients of any transport method using in particular the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) implementation of this theory as an example. We discuss the potentials used, the ground state initialization and the collision term, including the in-medium modifications of the latter. The central part of this review covers applications of GiBUU to a wide class of reactions, starting from pion-induced reactions over proton and antiproton reactions on nuclei to heavy-ion collisions (up to about 30 AGeV). A major part concerns also the description of photon-, electron- and neutrino-induced reactions (in the energy range from a few 100 MeV to a few 100 GeV). For this wide class of reactions GiBUU gives an excellent description with the same physics input and the same code being used. We argue that GiBUU is an indispensable tool for any investigation of nuclear reactions in which final-state interactions play a role. Studies of pion-nucleus interactions, nuclear fragmentation, heavy ion reactions, hyper nucleus formation, hadronization, color transparency, electron-nucleus collisions and neutrino-nucleus interactions are all possible applications of GiBUU and are discussed in this article.Comment: 173 pages, review article. v2: Text-rearrangements in sects. 2 and 3 (as accepted for publication in Physics Reports

Revista de educación

Número extraordinario 2006, con el título: PISA. Programa para la Evaluación Internacional de Alumnos. Resumen basado en el de la publicaciónSe analiza el rendimiento escolar, desde el punto de vista de los países en vías de desarrollo, del Programa para la Evaluación Internacional de Alumnos (PISA) de la Organización para la Cooperación y el Desarrollo Económico (OCDE), el Trends International Mathematics and Science Study (TIMSS) de la Asociación Internacional para la Evaluación del Rendimiento Educativo (IEA), y del Laboratorio Latinoamericano de Evaluación de la Calidad de la Educación (LLECE) gestionado por la Oficina Regional de la Educación de la UNESCO para América Latina y el Caribe. Se define el concepto de país en vías de desarrollo. Se conceptualiza a partir de cuatro aproximaciones: OCDE, Banco Mundial, Índice de Desarrollo Humano (IDH), e Índice de Transformación Bertelsmann (ITB). Se tienen en cuenta seis estudios: PISA 2000, PISA 2003, IEA 1973, TIMSS 1999, TIMSS 2003, y LLECE 1997. Se analizan los informes oficiales de los estudios anteriores y se presentan tanto en agregación global como por regiones del mundo. Se analizan algunas de las tendencias y se plantean conclusiones. Tanto el análisis como las conclusiones se basan en las posiciones relativas ocupadas por los países en los respectivos estudios y en aquellas de sus resultados nacionales con respecto a los promedios generales o referenciales. Se examinan los resultados de rendimiento entre las variables y las relacionadas con los antecedentes socioeconómicos, tanto a nivel individual como al de la escuela. Se investigan las relaciones de los elementos contenidos en los informes. Se destaca la gran cantidad de información en el caso de PISA frente al de TIMSS. Por último, se analiza la relevancia de los estudios internacionales para los países participantes en general y en particular para aquellos en vías de desarrollo, con comentarios a los estudios de las series PISA y TIMSS. Se recogen los datos en varias tablas.MadridBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]

Low-temperature wafer bonding using solid-liquid inter-diffusion mechanism

The low temperature joining of semiconductor substrates on wafer level by solid-liquid inter-diffusion bonding using the Cu/Ga and Au/In systems is investigated regarding the bonding parameters and their influence on bond interface properties. The focus is on temperature dependence and composition of interface. In the case of Cu/Ga bonding, a phase transition from CuGa2 to Cu9Ga4 was found to be primarily responsible for an increase in bonding strength. After the temperature treatment of 90°C, a shear strength of up to 90 MPa could be achieved. Furthermore, the combination of Au and In with composition ratios suitable for AuIn2 and AuIn intermetallic phase formation was investigated. In the case of AuIn shear strength, 96 MPa was achieved using a bonding temperature of 200°C

Fabrication of a multilayer spiral coil by selective bonding, debonding and MEMS technologies

For the further miniaturization of integrated circuits, the integration of passive components on the chip is one approach. In DC-DC converter applications, the integration of the inductor with high inductivity is one problem. This paper addresses this problem by proposing a new technique for fabricating a multilayer spiral coil that is also useful as part of electromagnetic MEMS (Micro-Electro-Mechanical Systems) actuators. The multilayer coil is made by stacking separately fabricated coil layers and joining them with a selective bonding and debonding technique

Monetary Policy, Corporate Finance and Investment

In response to a change in interest rates, younger firms not paying dividends adjust both their capital expenditure and borrowing significantly more than older firms paying dividends. The reason is that the debt of younger non-dividend payers is far more sensitive to fluctuations in collateral values, which are significantly affected by monetary policy. The results are robust to a wide range of possible confounding factors. Other channels, including movements in interest payments, product demand, profitability and mark-ups, are also significant but seem unlikely to explain the heterogeneity in the response of capital expenditure. Our findings suggest that these types of financial frictions play an important role in the transmission of monetary policy

Structure and thermoelectric properties of PbTe films deposited by thermal evaporation method

Lead telluride (PbTe) thin films have been deposited on SiO2 substrate using thermal evaporation method. The structure of the films was found to have a face-centered cubic (fcc) with predominant grain growth in the (200) direction for both as-deposited and annealed samples up to 350 °C in vacuum for 1 h. The in-plain electrical resistivity and Hall measurements via van der Pauw method as a function of annealed temperatures were measured. It was found that increasing the annealing temperature led to increase in grain size, which in turn caused decrease of electrical resistivity and increase of Seebeck coefficient. The high power factor of 141.0 μWm-1K-2 was obtained for the annealed samples at 350 °C in vacuum for 1 h

Multi-wafer bonding technology for the integration of a micromachined Mirau interferometer

The paper presents the multi-wafer bonding technology as well as the integration of electrical connection to the z-scanner wafer of the micromachined array-type Mirau interferometer. A Mirau interferometer, which is a key-component of optical coherence tomography (OCT) microsystem, consists of a microlens doublet, a MOEMS Z-scanner, a focus-adjustment spacer and a beam splitter plate. For the integration of this MOEMS device heterogeneous bonding of Si, glass and SOI wafers is necessary. Previously, most of the existing methods for multilayer wafer bonding require annealing at high temperature, i.e., 1100 degrees C. To be compatible with MEMS devices, bonding of different material stacks at temperatures lower than 400 degrees C has also been investigated. However, if more components are involved, it becomes less effective due to the alignment accuracy or degradation of surface quality of the not-bonded side after each bonding operation. The proposed technology focuses on 3D integration of heterogeneous building blocks, where the assembly process is compatible with the materials of each wafer stack and with position accuracy which fits optical requirement. A demonstrator with up to 5 wafers bonded lower than 400 degrees C is presented and bond interfaces are evaluated. To avoid the complexity of through wafer vias, a design which creates electrical connections along vertical direction by mounting a wafer stack on a flip chip PCB is proposed. The approach, which adopts vertically-stacked wafers along with electrical connection functionality, provides not only a space-effective integration of MOEMS device but also a design where the Mirau stack can be further integrated with other components of the OCT microsystem easily