Virulence Genotype and Phylogenetic Groups in relation to Chinese Herb Resistance among Escherichia Coli from Patients with acute Pyelonephritis

Background: Clinical isolates of herb-resistant uropathogenic E. coli were isolated. It was possible that the virulence genotypes and phylogenetic background of E. coli differed between Chinese herb-resistant E. coli and -susceptible isolates. For this purpose, the prevalence of virulence factors (VFs) and phylogenetic background, with regard to Chinese herb resistance, among E. coli strains causing acute pyelonephritis from China were investigated.Materials and Methods: E. coli isolates from patients with acute pyelonephritis were used in this study. Standard disc diffusion methodology was used to test the susceptibility of Chinese herbal concoction against E. coli strains. Multiplex PCR amplifications employed three markers (chuA, yjaA, and TSPE4.C2) to classify E. coli isolates into one of four phylogenetic groups (group A, B1, B2, or D). The isolates were also tested for 14 virulence-associated traits (VFs) of uropathogenic E. coli.Results: A total of 115 E. coli strains were isolated. 79 (68.7%) were susceptible and 36 (31.3%) were resistant to the herbal concoction. 20.9% of the isolates encoded three or more of VFs for which they were screened, with 13.9% in susceptible isolates and 36.1% in resistant isolates. The key VFs (fyuA and/or iutA siderophores) present in >80% of isolates. The papA and papC adhesins were detected in the majority of resistant isolates (72.2% and 63.9% respectively). 78.5% of susceptible isolates belong to phylogenetic groups A, while 83.3% of resistant isolates belong to group B2.Conclusion: PapA and papC are significant VFs with an essential role in contributing to Chinese herb-resistance. Chinese herb-resistance is associated with a shift towards more virulent strains and B2 phylogenetic group.Key words: Escherichia coli; Virulence factors; Phylogenetic group; Chinese herb-resistance

Pulsed THz radiation due to phonon-polariton effect in [110] ZnTe crystal

Pulsed terahertz (THz) radiation, generated through optical rectification (OR) by exciting [110] ZnTe crystal with ultrafast optical pulses, typically consists of only a few cycles of electromagnetic field oscillations with a duration about a couple of picoseconds. However, it is possible, under appropriate conditions, to generate a long damped oscillation tail (LDOT) following the main cycles. The LDOT can last tens of picoseconds and its Fourier transform shows a higher and narrower frequency peak than that of the main pulse. We have demonstrated that the generation of the LDOT depends on both the duration of the optical pulse and its central wavelength. Furthermore, we have also performed theoretical calculations based upon the OR effect coupled with the phonon-polariton mode of ZnTe and obtained theoretical THz waveforms in good agreement with our experimental observation.Comment: 9 pages, 5 figure

Constitutive modeling of steel-polypropylene hybrid fiber reinforced concrete using a non-associated plasticity and its numerical implementation

This paper presents a non-associated plasticity-based constitutive model for hybrid steel–polypropylene fiber reinforced concrete (HFRC) materials in an attempt to characterize the stress–strain responses under multiaxial loading scenarios. Together with a five-parameter loading surface and uncoupled hardening and softening regimes, a nonlinear plastic potential function is particularly introduced into the constitutive model with the material constants experimentally determined through a true triaxial compression test, which allows a more accurate estimation of the volumetric dilatency of HFRC. The influence of fiber parameters on the plastic flow direction is also addressed. Furthermore, the developed model is implemented into ABAQUS finite element package through a User-defined Material (UMAT) subroutine that can be applicable for the convenient use in numerical simulation of HFRC materials. A substepping scheme with error control for integrating the elasto-plastic stress–strain rate equations is presented in detail. Subsequently, the proposed model is evaluated by available multiaxial compression test results of both plain concrete and FRC reported by other researchers. It is shown that the constitutive model can realistically capture the stress–strain responses as well as the volumetric deformation of HFRC having various fiber reinforcement indices

Scanning tunneling spectroscopy of superconducting LiFeAs single crystals: Evidence for two nodeless energy gaps and coupling to a bosonic mode

The superconducting compound, LiFeAs, is studied by scanning tunneling microscopy and spectroscopy. A gap map of the unreconstructed surface indicates a high degree of homogeneity in this system. Spectra at 2 K show two nodeless superconducting gaps with $\Delta_1=5.3\pm0.1$ meV and $\Delta_2=2.5\pm0.2$ meV. The gaps close as the temperature is increased to the bulk $T_c$ indicating that the surface accurately represents the bulk. A dip-hump structure is observed below $T_c$ with an energy scale consistent with a magnetic resonance recently reported by inelastic neutron scattering

Exploring knowledge learning in collaborative information seeking process

Knowledge learning is recognized as an important component in people's search process. Existing studies on this topic usually measure the knowledge growth before and after a search. However, there still lacks a fine-grained understanding of users' knowledge change patterns within a search process and users' adoption of different sources for learning. In this on-going project, we are exploring answers to both questions in collaborative information seeking (CIS) since the CIS tasks are usually exploratory, which triggers learning, and involve diverse learning resources such as self-explored search content, partners' search content and explicit communication between them. Through analyzing the data from a controlled laboratory user study with both collaborative and individual information seeking conditions, we demonstrated that users' knowledge keeps growing in both conditions, but they issue significantly more diverse queries in the collaborative condition. Our analysis of users' queries also revealed that the adoption of different learning resources varies at different information seeking stages, and the adoption is influenced by the nature of search tasks too. Finally, we propose several insights for system design to enhance knowledge learning in collaborative information seeking process

Korteweg-de Vries description of Helmholtz-Kerr dark solitons

A wide variety of different physical systems can be described by a relatively small set of universal equations. For example, small-amplitude nonlinear Schrödinger dark solitons can be described by a Korteweg-de Vries (KdV) equation. Reductive perturbation theory, based on linear boosts and Gallilean transformations, is often employed to establish connections to and between such universal equations. Here, a novel analytical approach reveals that the evolution of small-amplitude Helmholtz–Kerr dark solitons is also governed by a KdV equation. This broadens the class of nonlinear systems that are known to possess KdV soliton solutions, and provides a framework for perturbative analyses when propagation angles are not negligibly small. The derivation of this KdV equation involves an element that appears new to weakly nonlinear analyses, since transformations are required to preserve the rotational symmetry inherent to Helmholtz-type equations

General analysis on the use of tesla's resonators in domino forms for wireless power transfer

In this paper, we present a brief overview of historical developments of wireless power and an analysis on the use of Tesla's resonators in domino forms for wireless power transfer. Relay resonators are spaced between the transmitter and receiver coils with the objectives of maximizing energy efficiency and increasing the overall transmission distance between the power source and the load. Analytical expressions for the optimal load and maximum efficiency at resonance frequency are derived. These equations are verified with practical measurements obtained from both coaxial and noncoaxial domino resonator systems. To avoid the use of high operating frequency for wireless power transfer in previous related research, the technique presented here can be used at submegahertz operation so as to minimize the power loss in both the power supply and the output stage. We demonstrated both theoretically and practically that unequal spacing for the coaxial straight domino systems has better efficiency performance than the equal-spacing method. Also, the flexibility of using resonators in various domino forms is demonstrated. © 2012 IEEE.published_or_final_versio