Quantum Critical Transport Near the Mott Transition

We perform a systematic study of incoherent transport in the high temperature crossover region of the half-filled one-band Hubbard model. We demonstrate that the family of resistivity curves displays characteristic quantum critical scaling of the form $\rho(\delta U,T)=\rho_{c}(T)f(T/T_{o}(\delta U))$, with $T_{o}(\delta U)\sim\delta U^{z\nu}$, and $\rho_{c}(T)\sim T$. The corresponding $\beta$-function displays a "strong coupling" form $\beta\sim\ln(\rho_{c}/\rho)$, reflecting the peculiar mirror symmetry of the scaling curves. This behavior, which is surprisingly similar to some experimental findings, indicates that Mott quantum criticality may be acting as the fundamental mechanism behind the unusual transport phenomena in many systems near the metal-insulator transition.Comment: Published version; 4+epsilon pages, 4 figure

Charge fluctuations, hydrodynamics and transport in the square-lattice Hubbard model

Recent experimental results suggest that a particular hydrodynamic theory describes charge fluctuations at long wavelengths in the square-lattice Hubbard model. Due to the continuity equation, the correlation functions for the charge and the current are directly connected: the parameters of the effective hydrodynamic model thus determine the optical conductivity. Here we investigate the validity of the proposed hydrodynamic theory in the full range of parameters of the Hubbard model. In the non-interacting case, there is no effective hydrodynamics, and the charge fluctuations present a rich variety of non-universal behaviors. At weak coupling, the optical conductivity is consistent with the hydrodynamic theory: at low frequency one observes a Lorentzian-shaped Drude peak, but the high-frequency asymptotics is necessarily different; the high-temperature limit for the product of the two hydrodynamic model parameters is also in agreement with numerical data. At strong coupling, we find that a generalization of the proposed hydrodynamic law is consistent with our quantum Monte Carlo, as well as the finite-temperature Lanczos results from literature. Most importantly, the temperature dependence of the hydrodynamic parameters as well as the dc resistivity are found to be very similar in the weak and the strong-coupling regimes.Comment: 27 pages, 23 figure

Detection and analysis of new psittacine beak and feather disease virus (PBFDv) nucleotide sequences

ΔΕΝ ΥΠΑΡΧΕΙ ΠΕΡΙΛΗΨΗPsittacine beak and feather disease (PBFD) affects a large number of Psittaciformes species. In this study, five White Cockatoo parrots (Cacatua alba) with clinical signs of PBFD were examined. After euthanasia, a full necropsy of parrots was performed and organs with macroscopic changes were sampled for routine histopathological evaluation. To confirm the presence of psittacine beak and feather disease virus (PBFDv), feather samples were analyzed with the PCR method. Sequence analysis of the obtained PCR products indicated their close relationship (99%) to other PBFDv isolates. Six variable nucleotide sites were discovered, two missense and four silent mutations. This paper presents the evidence of new PBFDv sequence in Cockatoo species

Occupational exposure to blood and body fluids among health-care workers in Serbia

© 2014 S. Karger AG, Basel. Objectives: The aim of this study was to examine the epidemiology of occupational accidents and self-reported attitude of health-care workers (HCWs) in Serbia. Subjects and Methods: A cross-sectional study was conducted among HCWs in selected departments of five tertiary care hospitals and in one secondary care hospital in February 2012. A previously developed self-administered questionnaire was provided to HCWs who had direct daily contact with patients. χ2 test and Student's t test were used for statistical analysis of the data. Results: Of the 1,441 potential participants, 983 (68.2%) completed the questionnaire: 655 (66.7%) were nurses/medical technicians, 243 (24.7%) were physicians and 85 (8.6%) were other personnel. Of the 983 participants, 291 (29.6%) HCWs had had at least one accident during the previous year and 106 (40.2%) of them reported it to the responsible person. The highest prevalence (68.6%) of accidents was among nurses/technicians (p = 0.001). Accidents occurred more often in large clinical centers (81.1%; p < 0.001) and in the clinical ward, intensive care unit and operating theater (p = 0.003) than in other departments. Seventy-six (13.1%) nurses/medical technicians had an accident during needle recapping (p < 0.001). Of all the HCWs, 550 (55.9%) were fully vaccinated, including significantly more doctors (154, 63.4%) than participants from other job categories (p < 0.001). Conclusion: There was a relatively high rate of accidents among HCWs in our hospitals, most commonly amongst nurses and staff working in clinical wards, intensive care units and operating theaters. The most common types of accidents were needlestick injuries and accidents due to improper handling of contaminated sharp devices or occuring while cleaning instruments or by coming into contact with blood through damaged skin or through the conjunctiva/mucous membranes

PROmiRNA: a new miRNA promoter recognition method uncovers the complex regulation of intronic miRNAs

The regulation of intragenic miRNAs by their own intronic promoters is one of the open problems of miRNA biogenesis. Here, we describe PROmiRNA, a new approach for miRNA promoter annotation based on a semi-supervised statistical model trained on deepCAGE data and sequence features. We validate our results with existing annotation, PolII occupancy data and read coverage from RNA-seq data. Compared to previous methods PROmiRNA increases the detection rate of intronic promoters by 30%, allowing us to perform a large-scale analysis of their genomic features, as well as elucidate their contribution to tissue-specific regulation. PROmiRNA can be downloaded from http://promirna.molgen.mpg.de