Risk Factors for Neonatal Sepsis and Method for Reduction of Blood Culture Contamination

Background: False-positive blood cultures findings may lead to a falsely increased morbidity and increased hospital costs.Method: The survey was conducted as retrospective - prospective study and included 239 preterm infants (born before 37 weeks of gestation) who were treated in Neonatal Intensive Care Unit (NICU) in Institute for Child and Youth Health Care of Vojvodina during one year (January 1st, 2012 to December 31st, 2012). The retrospective part of the study focused on examination of incidence of neonatal sepsis and determination of risk factors. In the prospective part of the study infants were sub-divided into two groups: Group 1- infants hospitalized in NICU during the first 6 months of the study; blood cultures were taken by the ‘’clean technique’’ and checklists for this procedure were not taken. Group 2- neonates hospitalized in NICU during last 6 months of the study; blood cultures were taken by ‘’sterile technique’’ and checklists for this procedure were taken.Results: The main risk factors for sepsis were prelabor rupture of membranes, low gestational age, low birth weight, mechanical ventilation, umbilical venous catheter placement, and abdominal drainage. Staphylococcus aureus and coagulase negative Staphylococcus were the most frequently isolated microorganisms in false-positive blood samples.Conclusions: Education of employees, use of checklists and sterile sets for blood sampling, permanent control of false positive blood cultures, as well as regular and routine monthly reports are crucial for successful reduction of contamination rates

Exact solution of electronic transport in semiconductors dominated by scattering on polaronic impurities

The scattering of electrons on impurities with internal degrees of freedom is bound to produce the signatures of the scatterer's own dynamics and results in nontrivial electronic transport properties. Previous studies of polaronic impurities in low-dimensional structures, like molecular junctions and one-dimensional nanowire models, have shown that perturbative treatments cannot account for a complex energy dependence of the scattering cross section in such systems. Here we derive the exact solution of polaronic impurities shaping the electronic transport in bulk (3D) systems. In the model with a short-ranged electron-phonon interaction, we solve for and sum over all elastic and inelastic partial cross sections, abundant in resonant features. The temperature dependence of the charge mobility shows the power-law dependence, $\mu(T)\propto T^{-\nu}$, with $\nu$ being highly sensitive to impurity parameters. The latter may explain nonuniversal power-law exponents observed experimentally, e.g. in high-quality organic molecular semiconductors.Comment: 5 pages, 6 figure

Electrodynamics of electron doped iron-pnictide superconductors: Normal state properties

The electrodynamic properties of Ba(Fe$_{0.92}$Co$_{0.08})_2$As$_{2}$ and Ba(Fe$_{0.95}$Ni$_{0.05})_As$_{2}$single crystals have been investigated by reflectivity measurements in a wide frequency range. In the metallic state, the optical conductivity consists of a broad incoherent background and a narrow Drude-like component which determines the transport properties; only the latter contribution strongly depends on the composition and temperature. This subsystem reveals a$T^2$behavior in the dc resistivity and scattering rate disclosing a hidden Fermi-liquid behavior in the 122 iron-pnictide family. An extended Drude analysis yields the frequency dependence of the effective mass (with$m^*/m_b\approx 5$ in the static limit) and scattering rate that does not disclose a simple power law. The spectral weight shifts to lower energies upon cooling; a significant fraction is not recovered within the infrared range of frequencies.Comment: 13 pages, 9 figure

Magnetic vortex lattice in HgBa2CuO4+x observed by small-angle neutron scattering

We report a direct observation of the magnetic vortex lattice in the model high-temperature superconductor HgBa2CuO4+x. Using small-angle neutron scattering on high-quality crystals, we observe two equal domains of undistorted triangular vortex lattices well-aligned with the tetragonal crystallographic axes. The signal decreases rapidly with increasing magnetic field and vanishes above 0.4 Tesla, which we attribute to a crossover from a three-dimensional to a two-dimensional vortex system, similar to previous results for the more anisotropic compound Bi2.15Sr1.95CaCu2O8+x. Our result indicates that a triangular vortex lattice at low magnetic fields is a generic property to cuprates with critical temperatures above 80 K.Comment: 6 pages, 4 figures, submitted to PR