The impact of high density receptor clusters on VEGF signaling

Vascular endothelial growth factor (VEGF) signaling is involved in the process of blood vessel development and maintenance. Signaling is initiated by binding of the bivalent VEGF ligand to the membrane-bound receptors (VEGFR), which in turn stimulates receptor dimerization. Herein, we discuss experimental evidence that VEGF receptors localize in caveloae and other regions of the plasma membrane, and for other receptors, it has been shown that receptor clustering has an impact on dimerization and thus also on signaling. Overall, receptor clustering is part of a complex ecosystem of interactions and how receptor clustering impacts dimerization is not well understood. To address these questions, we have formulated the simplest possible model. We have postulated the existence of a single high affinity region in the cell membrane, which acts as a transient trap for receptors. We have defined an ODE model by introducing high- and low-density receptor variables and introduce the corresponding reactions from a realistic model of VEGF signal initiation. Finally, we use the model to investigate the relation between the degree of VEGFR concentration, ligand availability, and signaling. In conclusion, our simulation results provide a deeper understanding of the role of receptor clustering in cell signaling.Comment: In Proceedings HSB 2013, arXiv:1308.572

UNTERSUCHUNG DER VERÄNDERUNGEN IN FADENS DIAMETER UND DREHUNGS-WINKEL BEI DER ZUG- UND DREHBEANSPRUCHUNG

The paper presents a method based on a special equipment and a projector microscope connected with an image processing system for measuring the diameter and the twist angle to study the cross-section contraction and the changes in the surface twist during tensile testing or twisting the yarns. As experimental studies polyester rayon yarn as well as ring-spun and rotor-spun yarns were tested and analysed. It is demonstrated how to use the results in modelling yarns

MODELLING THE BREAKING PROCESS OF TWISTED FIBRE BUNDLES AND YARNS

A brief description of a statistical modelling method is given to predict the total loading and breaking process of fibre bundles generated by the tensile test. Relationships between some normalized strength properties and the twist parameter of bundle, as well as the influence of the elastic part of the twist are examined by using the results of modelling an idealized structure of twisted fibre bundle. As an experimental study ring-spun and rotor-spun yarns are tested and their structure is analysed with the aid of comparing the measured and modelled breaking processes

Critical current of a Josephson junction containing a conical magnet

We calculate the critical current of a superconductor/ferromagnetic/superconductor (S/FM/S) Josephson junction in which the FM layer has a conical magnetic structure composed of an in-plane rotating antiferromagnetic phase and an out-of-plane ferromagnetic component. In view of the realistic electronic properties and magnetic structures that can be formed when conical magnets such as Ho are grown with a polycrystalline structure in thin-film form by methods such as direct current sputtering and evaporation, we have modeled this situation in the dirty limit with a large magnetic coherence length ($\xi_f$). This means that the electron mean free path is much smaller than the normalized spiral length $\lambda/2\pi$ which in turn is much smaller than $\xi_f$ (with $\lambda$ as the length a complete spiral makes along the growth direction of the FM). In this physically reasonable limit we have employed the linearized Usadel equations: we find that the triplet correlations are short ranged and manifested in the critical current as a rapid oscillation on the scale of $\lambda/2\pi$. These rapid oscillations in the critical current are superimposed on a slower oscillation which is related to the singlet correlations. Both oscillations decay on the scale of $\xi_f$. We derive an analytical solution and also describe a computational method for obtaining the critical current as a function of the conical magnetic layer thickness.Comment: Extended version of the published paper. Additional information about the computational method is included in the appendi

A. C. INVERTER DRIVE WITH FIELD ORIENTED CONTROL AND OPTIMUM PWM STRATEGY

The PWM procedures which are minimizing the losses origining from the upper har- monic currents can be applied at field oriented controls as well. Though at the execution of the field oriented control there is no possibility for the sudden change of phase angle position of the voltage vector the time duration of the transient process and the quality characteristics of it equal practically at the accurate execution of field oriented control strategy

Attosecond electronic and nuclear quantum photodynamics of ozone: time-dependent Dyson orbitals and dipole

A nonadiabatic scheme for the description of the coupled electron and nuclear motions in the ozone molecule was proposed recently. An initial coherent nonstationary state was prepared as a superposition of the ground state and the excited Hartley band. In this situation neither the electrons nor the nuclei are in a stationary state. The multiconfiguration time dependent Hartree method was used to solve the coupled nuclear quantum dynamics in the framework of the adiabatic separation of the time-dependent Schr\"odinger equation. The resulting wave packet shows an oscillation of the electron density between the two chemical bonds. As a first step for probing the electronic motion we computed the time-dependent molecular dipole and the Dyson orbitals. The latter play an important role in the explanation of the photoelectron angular distribution. Calculations of the Dyson orbitals are presented both for the time-independent as well as the time-dependent situations. We limited our description of the electronic motion to the Franck-Condon region only due to the localization of the nuclear wave packets around this point during the first 5-6 fs

Random Matrices and the Convergence of Partition Function Zeros in Finite Density QCD

We apply the Glasgow method for lattice QCD at finite chemical potential to a schematic random matrix model (RMM). In this method the zeros of the partition function are obtained by averaging the coefficients of its expansion in powers of the chemical potential. In this paper we investigate the phase structure by means of Glasgow averaging and demonstrate that the method converges to the correct analytically known result. We conclude that the statistics needed for complete convergence grows exponentially with the size of the system, in our case, the dimension of the Dirac matrix. The use of an unquenched ensemble at $\mu=0$ does not give an improvement over a quenched ensemble. We elucidate the phenomenon of a faster convergence of certain zeros of the partition function. The imprecision affecting the coefficients of the polynomial in the chemical potential can be interpeted as the appearance of a spurious phase. This phase dominates in the regions where the exact partition function is exponentially small, introducing additional phase boundaries, and hiding part of the true ones. The zeros along the surviving parts of the true boundaries remain unaffected.Comment: 17 pages, 14 figures, typos correcte

Hypothalamikus struktúrák glutamáterg innervációjának neurokémiai és funkcionális elemzése = Glutamatergic innervation of hypothalamic structures: neurochemical and functional analysis

A [3H]D-aszpartát szelektív felvételén és retrográd transzportján alapuló autoradiográfiás eljárással feltérképeztük a mediális preoptikus areába projiciáló glutamáterg idegsejtek lokalizációját. Leírtuk, hogy vezikuláris glutamát transzporter immunreaktív idegvégződések, melyeket specifikus glutamáterg elemeknek lehet tekinteni, aszimmetrikus szinapszissal kapcsolódnak gonadotrop hormon-releasing hormon immunpozitív neuronokhoz a mediális preoptikus areában, neuropeptid Y, növekedési hormon-releasing hormon és pro-opiomelanocortin tartalmú idegsejtekhez a n. arcuatusban, szomatosztatinerg neuronokhoz a n. periventricularis anteriorban, valamint GABAerg, vazoaktív intesztinális polipeptidet és arginin-vazopresszint tartalmazó idegsejtekhez a n. suprachiasmaticusban. Kimutattuk, hogy nem-NMDA-receptor antagonista a n. paraventricularis hypothalamiba adva blokkolta a szopási inger valamint a formalin-stressz által kiváltott hypophysis prolaktin felszabadulást. | By means of the transmitter specific [3H]D-aspartate retrograde tracing technique we detected the location of glutamatergic neurons projecting to the medial preoptic area. We demonstrated synaptic contacts of the asymmetric type between vesicular glutamate transporter type 2 (selective marker of glutamatergic elements) nerve terminals and various neurons such as gonadotrop hormone-releasing hormone immunoreactive neurons in the medial preoptic area, neuropeptide Y, growth hormone-releasing hormone and pro-opiomelanocortin containing neurons in the arcuate nucleus, somatostatinerg nerve cells in the anterior periventricular nucleus and GABA, vasoactive intestinal polypeptide and arginine-vasopressin immunoreactive neurons in the suprachiasmatic nucleus. We observed that non-NMDA receptor antagonist injected into the hypothalamic paraventricular nucleus blocked the suckling stimulus-induced rise in plasma prolactin and the prolactin response to formalin stress