Thermodynamics and optical conductivity of unconventional spin density waves

We consider the possibility of formation of an unconventional spin density wave (USDW) in quasi-one dimensional electronic systems. In analogy with unconventional superconductivity, we develop a mean field theory of SDW allowing for the momentum dependent gap $\Delta({\bf k})$ on the Fermi surface. Conditions for the appearence of such a low temperature phase are investigated. The excitation spectrum and basic thermodynamic properties of the model are found to be very similar to those of d-wave superconductors in spite of the different topology of their Fermi surfaces. Several correlation functions are calculated, and the frequency dependent conductivity is evaluated for various gap functions. The latter is found to reflect the maximum gap value, however with no sharp onset for absorbtion.Comment: 13 pages, 11 figures, submitted to Phys. Rev.

Unconventional charge density wave driven by electron-phonon coupling

We report our study on unconventional charge density waves (UCDW) (i.e. a charge density wave with wavevector dependent gap) in pure quasi-one dimensional conductors. We develop a new possible mechanism of establishment of such a low temperature phase, in which the driving force of the phase transition is the electron-phonon interaction with coupling depending on both the momentum transfer q and the momentum of the scattered electron k. Mean field treatment is applied to obtain the excitation spectrum, correlation functions such as the density correlator and the optical conductivity, and the effective mass of the phase excitation. The fluctuation of the order parameter leads to the sliding of the UCDW as a whole. In the absence of impurities, we calculated the effect of this fluctuation on the optical properties. The inclusion of the collective mode significantly alters the optical conductivity, and leads to an effective mass which is nonmonotonic in temperature as opposed to conventional CDWs.Comment: 11 figures, 13 pages, Revtex4 styl

Magnetotransport in d-wave density waves

Angle dependent magnetoresistance (ADMR) and giant Nernst effect are hallmarks of unconventional density waves (UDW). Here these transport properties for d-wave density wave (d-DW) are computed for quasi-two-dimensional systems. The present theory describes ADMR observed in the pseudogap phase of Y_0.68Pr_0.32Ba_2Cu_3O_7 and CeCoIn_5 single crystals very satisfactorily.Comment: 7 pages, 6 figure

Aggregation of Heterogeneous Flexibility Resources Providing Services for System Operators and the Market Participants

Power systems characterized by large, centralized generation sources and the typical flow of energy from the transmission grid to the distribution grid towards consumers are evolving. The increasing penetration of intermittent and distributed renewable energy generation is forcing system operators to increase the volume of balancing capabilities and procure flexibility services at the distribution grid level that must be supported by the aggregation of small-scale resources connected at the distribution grid. This paper suggests an aggregator framework that provides services for both operators of transmission and distribution systems while optimizes its portfolio to perform on wholesale energy trading markets too. Overlaying phases of multi-period optimization runs are proposed that incorporate stochastic renewable energy generation as well as load forecasts and, moreover, the continuously changing business context while enabling cooperation between optimization phases throughout the business process

Akut és szubakut klinikai állapotok radiológiai intervenciója: fókuszban a nem vascularis intervenciók es a haemoptysis kezelése

Interventional radiology provides fast, straightforward and tolerable solutions for many medical problems including acute and subacute situations. Aspiration and drainage of fluid collections, biliary and endourologic interventions and gastrointestinal interventions are parts of non-vascular interventions. In addition, the authors discuss in detail interventional radiological treatment options in patients with hemoptysis. In acute cases interventions must be performed within 12-24 hours. For background, an everyday 24 hours service should be provided with well-trained personnel, high quality equipment and devices, and a reasonable financial reimbursement should be included, too. Multidisciplinary teamwork, consultations, consensus in indications and structured education should make these centers function most effectively

Local density of states and Friedel oscillations around a non-magnetic impurity in unconventional density wave

We present a mean-field theoretical study on the effect of a single non-magnetic impurity in quasi-one dimensional unconventional density wave. The local scattering potential is treated within the self-consistent $T$-matrix approximation. The local density of states around the impurity shows the presence of resonant states in the vicinity of the Fermi level, much the same way as in $d$-density waves or unconventional superconductors. The assumption for different forward and backscattering, characteristic to quasi-one dimensional systems in general, leads to a resonance state that is double peaked in the pseudogap. The Friedel oscillations around the impurity are also explored in great detail, both within and beyond the density wave coherence length $\xi_0$. Beyond $\xi_0$ we find power law behavior as opposed to the exponential decay of conventional density wave. The entropy and specific heat contribution of the impurity are also calculated for arbitrary scattering strengths.Comment: 13 pages, 4 figure