Modification of the carboxy-terminal flanking region of a universal influenza epitope alters CD4+ T-cell repertoire selection

Human CD4+ αβ T cells are activated via T-cell receptor recognition of peptide epitopes presented by major histocompatibility complex (MHC) class II (MHC-II). The open ends of the MHC-II binding groove allow peptide epitopes to extend beyond a central nonamer core region at both the amino- and carboxy-terminus. We have previously found that these non-bound C-terminal residues can alter T cell activation in an MHC allele-transcending fashion, although the mechanism for this effect remained unclear. Here we show that modification of the C-terminal peptide-flanking region of an influenza hemagglutinin (HA305−320) epitope can alter T-cell receptor binding affinity, T-cell activation and repertoire selection of influenza-specific CD4+ T cells expanded from peripheral blood. These data provide the first demonstration that changes in the C-terminus of the peptide-flanking region can substantially alter T-cell receptor binding affinity, and indicate a mechanism through which peptide flanking residues could influence repertoire selection

Extravasation of leukocytes in comparison to tumor cells

The multi-step process of the emigration of cells from the blood stream through the vascular endothelium into the tissue has been termed extravasation. The extravasation of leukocytes is fairly well characterized down to the molecular level, and has been reviewed in several aspects. Comparatively little is known about the extravasation of tumor cells, which is part of the hematogenic metastasis formation. Although the steps of the process are basically the same in leukocytes and tumor cells, i.e. rolling, adhesion, transmigration (diapedesis), the molecules that are involved are different. A further important difference is that leukocyte interaction with the endothelium changes the endothelial integrity only temporarily, whereas tumor cell interaction leads to an irreversible damage of the endothelial architecture. Moreover, tumor cells utilize leukocytes for their extravasation as linkers to the endothelium. Thus, metastasis formation is indirectly susceptible to localization signals that are literally specific for the immune system. We herein compare the extravasation of leukocytes and tumor cells with regard to the involved receptors and the localization signals that direct the cells to certain organs and sites of the body

Jet quenching

We present a comprehensive review of the physics of hadron and jet production at large transverse momentum in high-energy nucleus-nucleus collisions. Emphasis is put on experimental and theoretical "jet quenching" observables that provide direct information on the (thermo)dynamical properties of hot and dense QCD matter.Comment: Springer Verlag. Landolt-Boernstein Vol. 1-23A. 49 pages. 36 figures. Minor corrections & references adde

Micro-inverter for integrated grid-tie photovoltaic module using resonant controller

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Two-stage isolated converters for photovoltaic (PV) applications commonly employ a high-frequency transformer (HFT) on the DC-DC side, submitting the DC-AC inverter switches to high voltages and forcing the use of insulated-gate bipolar transistors instead of low-voltage and low-loss metal-oxide-semiconductor field-effect transistors. This paper shows the modeling, control and simulation of a single-phase full-bridge inverter with HFT that can be used as part of a two-stage converter with transformerless DC-DC side or as a single-stage converter (simple DC-AC inverter) for grid-connected PV applications. The inverter is modeled to obtain a small-signal transfer function used to design the P+Resonant current control regulator, whose main advantages are the simplicity for implementation in single-phase systems and zero steady state error with sinusoidal current. A high-frequency step-up transformer results in low-voltage switches and better efficiency compared with converters in which the transformer is used on the DC-DC side. Simulations and experimental results with a 200-W prototype are shown. Copyright (c) 2013 John Wiley & Sons, Ltd.245713722Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [10/15848-7, 08/07956-4, 10/50101-0

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array datasheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.24417951198120