Methodology of geotechnical design as applied on the Sveti Marko tunnel

Integralna metoda projektiranja objedinjuje empirijski, racionalni i opažački pristup projektiranju tunela. Opisuje se primjena integralne metode na tunelu Sv. Marko koja je omogućila potpunu kontrolu nad geotehničkom konstrukcijom tunela u svim fazama izvedbe te uspješni završetak gradnje. Prikazana su projektna rješenja, program i druga faza projektiranja, tehnologija izvođenja, rezultati mjerenja i povratne analize te intervencije tijekom gradnje.The paper starts with the assertion that the integral method of design combines empirical, rational and observational approaches to tunnel design. The application of the integral method at the Sveti Marko tunnel is described. This method enabled the total control of the geotechnical structure of the tunnel in all phases of realization, and allowed successful completion of the construction work. The authors present design solutions, the program and the second stage of design, construction technology, back analysis and measurement results, and interventions made in the course of tunnel construction..

Polyphenols as Inhibitors of Antibiotic Resistant Bacteria-Mechanisms Underlying Rutin Interference with Bacterial Virulence

The rising incidence of antibiotic resistant microorganisms urges novel antimicrobials development with polyphenols as appealing potential therapeutics. We aimed to reveal the most promising polyphenols among hesperetin, hesperidin, naringenin, naringin, taxifolin, rutin, isoquercitrin, morin, chlorogenic acid, ferulic acid, p-coumaric acid, and gallic acid based on antimicrobial capacity, antibiofilm potential, and lack of cytotoxicity towards HaCaT, and to further test its antivirulence mechanisms. Although the majority of studied polyphenols were able to inhibit bacterial growth and biofilm formation, the most promising activities were observed for rutin. Further investigation proved rutin's ability to prevent/eradicate Pseudomonas aeruginosa and MRSA urinary catheter biofilms. Besides reduction of biofilm biomass, rutin antibiofilm mechanisms included reduction of cell viability, exopolysaccharide, and extracellular DNA levels. Moderate reduction of bacterial adhesion to human keratinocytes upon treatment was observed. Rutin antivirulence mechanisms included an impact on P. aeruginosa protease, pyocyanin, rhamnolipid, and elastase production and the downregulation of the lasI, lasR, rhlI, rhlR, pqsA and mvfR genes. Rutin also interfered with membrane permeability. Polyphenols could repress antibiotic resistant bacteria. Rutin has shown wide antimicrobial and antibiofilm capacity employing a range of mechanisms that might be used for the development of novel antimicrobials

Universal Relationship Between Giant Magnetoresistance and Anisotropic Magnetoresistance in Spin Valve Multilayers

We measure the giant magnetoresistance (GMR) with the current both parallel and perpendicular to the direction of the magnetization in the ferromagnetic (FM) layers and thus probe the anisotropy of the effective mean free paths for the spin-up and spin-down electrons, seen in the anisotropic magnetoresistance. We find that the difference of the GMR in the two configurations, when expressed in terms of the sheet conductance, displays a nearly universal behavior as a function of GMR. On interpreting the results within the Boltzmann transport formalism we demonstrate the importance of bulk scattering for GMR.Comment: REVTEX, 2 figure

Weak Pseudogap Behavior in the Underdoped Cuprate Superconductors

We report on an exact solution of the nearly antiferromagnetic Fermi liquid spin fermion model in the limit \pi T << \omega_{sf}, which demonstrates that the broad high energy features found in ARPES measurements of the spectral density of the underdoped cuprate superconductors are determined by strong antiferromagnetic (AF) correlations and precursor effects of an SDW state. We show that the onset temperature, T^{cr}, of weak pseudo-gap (pseudoscaling) behavior is determined by the strength, \xi, of the AF correlations, and obtain the generic changes in low frequency magnetic behavior seen in NMR experiments with \xi(T^{cr}) \approx 2, confirming the Barzykin and Pines crossover criterion.Comment: REVTEX, 4 pages, 3 EPS figure

Theory of the Optical Conductivity in the Cuprate Superconductors

We present a study of the normal state optical conductivity in the cuprate superconductors using the nearly antiferromagnetic Fermi liquid (NAFL) description of the magnetic interaction between their planar quasiparticles. We find that the highly anisotropic scattering rate in different regions of the Brillouin zone, both as a function of frequency and temperature, a benchmark of NAFL theory, leads to an average relaxation rate of the Marginal Fermi Liquid form for overdoped and optimally doped systems, as well as for underdoped systems at high temperatures. We carry out numerical calculations of the optical conductivity for several compounds for which the input spin fluctuation parameters are known. Our results, which are in agreement with experiment on both overdoped and optimally doped systems, show that NAFL theory explains the anomalous optical behavior found in these cuprate superconductors.Comment: REVTEX file, 8 PostScript figure

Antiferromagnetic Excitations and Van Hove Singularities in YBa2_2Cu3_3O6+x_{6+x}

We show that in quasi-two-dimensional $d$-wave superconductors Van Hove singularities close to the Fermi surface lead to novel magnetic quasi-particle excitations. We calculate the temperature and doping dependence of dynamical magnetic susceptibility for YBCO and show that the proposed excitations are in agreement with inelastic neutron scattering experiments. In addition, the values of the gap parameter and in-plane antiferromagnetic coupling are much smaller than usually believed.Comment: REVTeX, 4 pages + 3 PostScript (compressed) figures; to appear in Phys. Rev. B (Rap. Comm.

The Anomalous Hall Effect in YBa2_2Cu3_3O7_7

The temperature dependence of the normal state Hall effect and magnetoresistance in YBa$_2$Cu$_3$O$_7$ is investigated using the Nearly Antiferromagnetic Fermi Liquid description of planar quasiparticles. We find that highly anisotropic scattering at different regions of the Fermi surface gives rise to the measured anomalous temperature dependence of the resistivity and Hall coefficient while yielding the universal temperature dependence of the Hall angle observed for both clean and dirty samples. This universality is shown to arise from the limited momentum transfers available for the anomalous, spin fluctuation scattering and is preserved for any system with strong antiferromagnetic correlations.Comment: REVTeX, 10 pages + 4 figures in a single (compressed/uuencoded) PostScript fil

Microscopic theory of weak pseudogap behavior in the underdoped cuprate superconductors I: General theory and quasiparticle properties

We derive in detail a novel solution of the spin fermion model which is valid in the quasi-static limit pi T<<omega_sf, found in the intermediate (pseudoscaling) regime of the magnetic phase diagram of cuprate superconductors, and use it to obtain results for the temperature and doping dependence of the single particle spectral density, the electron-spin fluctuation vertex function, and the low frequency dynamical spin susceptibility. The resulting strong anisotropy of the spectral density and the vertex function lead to the qualitatively different behavior of_hot_ (around k=(pi,0)) and_cold_ (around k=(pi/2,pi/2)) quasiparticles seen in ARPES experiments. We find that the broad high energy features found in ARPES measurements of the spectral density of the underdoped cuprate superconductors are determined by strong antiferromagnetic (AF) correlations and incoherent precursor effects of an SDW state, with reduced renormalized effective coupling constant. The electron spin-fluctuation vertex function, i.e. the effective interaction of low energy quasiparticles and spin degrees of freedom, is found to be strongly anisotropic and enhanced for hot quasiparticles; the corresponding charge-fluctuation vertex is considerably diminished. We thus demonstrate that, once established, strong AF correlations act to reduce substantially the effective electron-phonon coupling constant in cuprate superconductors.Comment: REVTEX with EPS figures, uses multicol.sty, epsfig,sty, psfig.st

On the Origin of Peak-dip-hump Structure in the In-plane Optical Conductivity of the High TCT_C Cuprates; Role of Antiferromagnetic Spin Fluctuations of Short Range Order

An improved U(1) slave-boson approach is applied to study the optical conductivity of the two dimensional systems of antiferromagnetically correlated electrons over a wide range of hole doping and temperature. Interplay between the spin and charge degrees of freedom is discussed to explain the origin of the peak-dip-hump structure in the in-plane conductivity of high $T_C$ cuprates. The role of spin fluctuations of short range order(spin singlet pair) is investigated. It is shown that the spin fluctuations of the short range order can cause the mid-infrared hump, by exhibiting a linear increase of the hump frequency with the antiferromagnetic Heisenberg coupling strength