Effective model of the electronic Griffiths phase

We present simple analytical arguments explaining the universal emergence of electronic Griffiths phases as precursors of disorder-driven metal-insulator transitions in correlated electronic systems. A simple effective model is constructed and solved within Dynamical Mean Field Theory. It is shown to capture all the qualitative and even quantitative aspects of such Griffiths phases.Comment: 9 pages, 7 figures, one reference corrected; minor corrections include

Mechanism of hopping transport in disordered Mott insulators

By using a combination of detailed experimental studies and simple theoretical arguments, we identify a novel mechanism characterizing the hopping transport in the Mott insulating phase of Ca$_{2-x}$Sr$_x$RuO$_4$ near the metal-insulator transition. The hopping exponent $\alpha$ shows a systematic evolution from a value of $\alpha=1/2$ deeper in the insulator to the conventional Mott value $\alpha=1/3$ closer to the transition. This behavior, which we argue to be a universal feature of disordered Mott systems close to the metal-insulator transition, is shown to reflect the gradual emergence of disorder-induced localized electronic states populating the Mott-Hubbard gap.Comment: 5 pages, 3 figures, To be published in Physical Review Letter

Anatomy and radiology of the variations of aortic arch branches in 1,266 patients

Background: The most reliable data about arterial variations, which are very important in surgery and radiology, can be obtained from a large series of patients.Materials and methods: We examined angiographic and multislice computerised tomography (MSCT) images in a group of 1,265 patients and in 1 dissected specimen.Results: While in 946 (74.72%) of the patients a normal vascular pattern (type I) was noticed, in the remaining 320 (25.28%) patients variations of the branchesof the aortic arch were found, which were classified into types II through VIII and a few subtypes. Type II (2.84%) comprised a common origin of the left commoncarotid and subclavian arteries. Type III (15.56%) was related to an origin of the left subclavian artery from the brachiocephalic trunk. Type IV (0.55%) includedthe aortic origin of both common carotid and subclavian arteries, with the rightsubclavian artery having a retroesophageal course. Type V (0.24%) included thesame 4 supra-aortic branches, which, however, arose from a double or a right--sided aortic arch. Type VI (3.63%) comprised the aortic origin of the left vertebralartery, type VII (0.24%) the same origin of the right vertebral artery, and type VIII(2.22%) the aortic origin of the thyroideaima artery. A corresponding embryological background and clinical implications of the described aberrant vessels were presented.Conclusions: In more than one quarter of the cases, the branching pattern of the examined arteries did not follow the classical pattern. Detailed knowledge of aortic branch variations is of great significance in anatomy, embryology, andclinical medicine, especially in radiology and thoracic surgery

ARTreat Project: Three-Dimensional Numerical Simulation of Plaque Formation and Development in the Arteries

Atherosclerosis is a progressive disease characterized by the accumulation of lipids and fibrous elements in arteries. It is characterized by dysfunction of endothelium and vasculitis, and accumulation of lipid, cholesterol, and cell elements inside blood vessel wall. In this study, a continuum-based approach for plaque formation and development in 3-D is presented. The blood flow is simulated by the 3-D Navier-Stokes equations, together with the continuity equation while low-density lipoprotein (LDL) transport in lumen of the vessel is coupled with Kedem-Katchalsky equations. The inflammatory process was solved using three additional reaction-diffusion partial differential equations. Transport of labeled LDL was fitted with our experiment on the rabbit animal model. Matching with histological data for LDL localization was achieved. Also, 3-D model of the straight artery with initial mild constriction of 30% plaque for formation and development is presented

Optical conductivity and vibrational spectra of the narrow-gap semiconductor FeGa3_3

Intermetallic narrow-gap semiconductors have been intensively explored due to their large thermoelectric power at low temperatures and a possible role of strong electronic correlations in their unusual thermodynamic and transport properties. Here we study the optical spectra and vibrational properties of $\mathrm{FeGa_3}$ single crystal. The optical conductivity indicates that $\mathrm{FeGa_3}$ has a direct band gap of $\sim 0.7$\,eV, consistent with density functional theory (DFT) calculations. Most importantly, we find a substantial spectral weight also below 0.4~eV, which is the energy of the indirect (charge) gap found in resistivity measurements and ab initio calculations. We find that the spectral weight below the gap decreases with increasing temperature, which indicates that it originates from the impurity states and not from the electronic correlations. Interestingly, we did not find any signatures of the impurity states in vibrational spectra. The infrared and Raman vibrational lines are narrow and weakly temperature dependent. The vibrational frequencies are in excellent agreement with our DFT calculations, implying a modest role of electronic correlations. Narrow M\" ossbauer spectral lines also indicate high crystallinity of the sample