Vector-resonance-multimode instability

The modulation and multimode instabilities are the main mechanisms which drive spontaneous spatial and temporal patterns formation in a vast number of nonlinear systems ranging from biology to the laser physics. Using Er-doped fiber laser as a test bed, here for the first time we demonstrate both experimentally and theoretically a new type of a low threshold vector resonance multimode instability which inherits features of multimode and modulation instabilities. The same as for the multimode instability, the large number of longitudinal modes can be excited without modes synchronization. To enable modulation instability, we modulate the state of polarization of the lasing signal with the period of the beat length by adjustment of the in-cavity birefringence and the state of polarization of the pump wave. As a result, we show regimes tunability from complex oscillatory to periodic with longitudinal modes synchronization in the case of the resonance matching between beat and cavity lengths. Apart from the interest in laser physics for unlocking tunability and stability of dynamic regimes, the proposed mechanism of the vector resonance multimode instability can be of fundamental interest for nonlinear dynamics of various distributed systems

Research organic light-emitting diodes with colloidal quantum dots

In this research we have created light-emitting structures that contain colloidal quantum dots of cadmium selenide in the active layer. To do so, we have used the method of vacuum thermal deposition for the formation of organic layers. This method allowed us to create several OLED structures. We have compared their photo- and electroluminescence spectra, and have revealed necessary conditions for the creation of high quality layers

Decoupling of heavy quarks in HQET

Decoupling of c-quark loops in b-quark HQET is considered. The decoupling coefficients for the HQET heavy-quark field and the heavy-light quark current are calculated with the three-loop accuracy. The last result can be used to improve the accuracy of extracting f_B from HQET lattice simulations (without c-quark loops). The decoupling coefficient for the flavour-nonsinglet QCD current with n antisymmetrized gamma-matrices is also obtained at three loops; the result for the tensor current (n=2) is new.Comment: JHEP3 documentclass; the results in a computer-readable form can be found at http://www-ttp.physik.uni-karlsruhe.de/Progdata/ttp06/ttp06-25/ V2: a few typos corrected, a few minor text improvements, a few references added; V3: several typos in formulas fixe

A Gribov equation for the photon Green's function

We present a derivation of the Gribov equation for the gluon/photon Green's function D(q). Our derivation is based on the second derivative of the gauge-invariant quantity Tr ln D(q), which we interpret as the gauge-boson `self-loop'. By considering the higher-order corrections to this quantity, we are able to obtain a Gribov equation which sums the logarithmically enhanced corrections. By solving this equation, we obtain the non-perturbative running coupling in both QCD and QED. In the case of QCD, alpha_S has a singularity in the space-like region corresponding to super-criticality, which is argued to be resolved in Gribov's light-quark confinement scenario. For the QED coupling in the UV limit, we obtain a \propto Q^2 behaviour for space-like Q^2=-q^2. This implies the decoupling of the photon and an NJLVL-type effective theory in the UV limit.Comment: 12 pages, 5 figures; version to be published in Eur. Phys. J.

The four-loop beta-function in Quantum Chromodynamics

We present the analytical calculation of the four-loop QCD beta-function within the minimal subtraction scheme.Comment: 9 pages, Latex, 1 figure, uses axodraw.st

The 4-loop quark mass anomalous dimension and the invariant quark mass

We present the analytical calculation of the four-loop quark mass anomalous dimension in Quantum Chromodynamics within the minimal subtraction scheme. On the basis of this result we find that the so-called invariant quark mass is a very good reference mass for the accurate evolution of the running MS-bar quark mass in phenomenological applications. We also obtain for the first time a complete 4-th order perturbative QCD expression for a physical quantity, the total Higgs boson decay rate into hadrons, and analyze the infrared fixed point for this case.Comment: 11 pages, Late

Receptor tyrosine kinase activation of RhoA is mediated by AKT phosphorylation of DLC1

We report several receptor tyrosine kinase (RTK) ligands increase RhoA-guanosine triphosphate (GTP) in untransformed and transformed cell lines and determine this phenomenon depends on the RTKs activating the AKT serine/threonine kinase. The increased RhoA-GTP results from AKT phosphorylating three serines (S298, S329, and S567) in the DLC1 tumor suppressor, a Rho GTPase-activating protein (RhoGAP) associated with focal adhesions. Phosphorylation of the serines, located N-terminal to the DLC1 RhoGAP domain, induces strong binding of that N-terminal region to the RhoGAP domain, converting DLC1 from an open, active dimer to a closed, inactive monomer. That binding, which interferes with the interaction of RhoA-GTP with the RhoGAP domain, reduces the hydrolysis of RhoA-GTP, the binding of other DLC1 ligands, and the colocalization of DLC1 with focal adhesions and attenuates tumor suppressor activity. DLC1 is a critical AKT target in DLC1-positive cancer because AKT inhibition has potent antitumor activity in the DLC1-positive transgenic cancer model and in a DLC1-positive cancer cell line but not in an isogenic DLC1-negative cell line

The Large Quark Mass Expansion of Gamma (Z^0 -> hadrons) and Gamma(tau^- -> nu_tau + hadrons) in the Order alpha_s^3

We present the analytical $\alpha_{s}^3$ correction to the $Z^{0}$ decay rate into hadrons. We calculate this correction up to (and including) terms of the order $(m_Z^2/m_{top}^2)^3$ in the large top quark mass expansion. We rely on the technique of the large mass expansion of individual Feynman diagrams and treat its application in detail. We convert the obtained results of six flavour QCD to the results in the effective theory with five active flavours, checking the decoupling relation of the QCD coupling constant. We also derive the large charm quark mass expansion of the semihadronic $\tau$ lepton decay rate in the $\alpha_{s}^3$ approximation.Comment: Postscript generation repaired, The complete postscript file of this article, including figures, is now available at ftp://nikhefh.nikhef.nl/pub/preprints/H94-30.ps.g

Functioning of linear induction accelerator of electrons LIA-30 in the mode of simultaneous forming and acceleration of 2 - 3 high-current relativistic electron beams

The carried out experimental investigations of LIA-30 accelerator injection system as well as the new data on standard operation modes testing in bremsstrahlung pulse generation made it possible to take a new view of electrophysical processes taking place in the accelerating track. In spite of success achieved in searching for optimal acceleration conditions – namely, limitation of edge steepness and amplitude of injection current pulses, definition of the program of forming voltage pulses that accelerate electrons etc. – there still remains to acute the task of decreasing lateral oscillations of high-current relativistic electron beam along the track as a whole and especially in cathode-anode gap where the influence of longitudinal magnetic field irregularities is most evident. When the magnetic field is limited in the track what is related to technical potentialities, the oscillations decrease in the injection system equipped with a two-beam cathode. Moreover, this process of electron beam acceleration becomes more stable even under conditions of parameter changes in the accelerator subsystem operation

The next-to-leading QCD approximation to the Ellis-Jaffe sum rule

The \alpha_s^2 correction to the Ellis-Jaffe sum rule for the structure function g_1 of polarized deep inelastic lepton-nucleon scattering is calculated.Comment: 9 pages, latex, CERN-TH.7208/9