Non-linear response to electric field in extended Hubbard models

The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various non-linear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the {\it fidelity susceptibility} of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time-scales as long as the fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating regime, dissipative regime or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular

Field effect on surface states in a doped Mott-Insulator thin film

Surface effects of a doped thin film made of a strongly correlated material are investigated both in the absence and presence of a perpendicular electric field. We use an inhomogeneous Gutzwiller approximation for a single band Hubbard model in order to describe correlation effects. For low doping, the bulk value of the quasiparticle weight is recovered exponentially deep into the slab, but with increasing doping, additional Friedel oscillations appear near the surface. We show that the inverse correlation length has a power-law dependence on the doping level. In the presence of an electrical field, considerable changes in the quasiparticle weight can be realized throughout the system. We observe a large difference (as large as five orders of magnitude) in the quasiparticle weight near the opposite sides of the slab. This effect can be significant in switching devices that use the surface states for transport

Population's perspectives toward biobanks in scientific research: a study from Jordan.

BackgroundBiobanks (biorepositories) were established to compile collected bio-specimens for future research and usage. The collection/storage of bio-specimens triggers several social, legal, and ethical implications where public attitudes can represent the core measurement/parameter in defining the most acceptable practices and ethical approaches when dealing with biobanks.AimThe aim of this study was to explore and understand population's perspectives, expectations, and concerns toward biobanks in Jordan.MethodsA cross-sectional survey that included closed-ended questions was distributed among Jordanians. A total of 500 participants who are representative of the Jordanian population were included in this study.ResultsThere was overwhelming support (>85%) for the establishment of biobanks in Jordan, and most of the participants agreed on the importance of biobanks and samples' donation for promoting medical research. Enthusiasm in biobanking participation was associated with the sociodemographic characteristics of participants including age, educational level, and previous knowledge of biobanks. Moreover, considering sample donation as a religiously good deed appeared to have the strongest positive correlation with willingness to donate bio-specimens for future research. Also, participants' trust in medical and research services, especially the protection of their privacy and confidentiality, was the most critical concern when they decided to participate in biobanks.ConclusionPopulation's attitude toward biobanks in Jordan was positive and promising, and can encourage the future establishment of different biobanks. It is also necessary to take into consideration certain sociodemographic characteristics when discussing specific information with potential biobanks' donors

Seedling emergence as influenced by aggregate size and bulk density

Non-Peer ReviewedProducers in western Canada are becoming increasingly interested in conservation tillage. A thorough understanding of how seedlings interact with the soil surrounding them is required to develop criteria for designing effective furrow openers and packing devices suitable for use in conservation tillage systems. To facilitate interpretation of the results of a field evaluation study of furrow openers for zero tillage seeders,·we conducted a greenhouse experiment designed to assess the impact of bulk density and aggregate size distribution of the seedbed on the emergence of Hard Red Spring Wheat (Triticum aestivum L). Seeds of wheat (c.v. Lancer) were germinated in seedbeds with five aggregate size distributions with geometric mean diameter ranging from 0.44 to 12.67 mm, and four bulk densities ranging from 1.0 to L6 Mg m-3 arranged in a factorial design. The soil used in this study was taken from the Ap horizon of a Swinton silt loam (Orthic Brown Chernozemic). Number of seedlings emerged and speed of emergence were affected by bulk density and aggregate size of the seedbed, and by the interaction of both variables. In general increasing bulk density or aggregate size reduced and delayed emergence, but in seedbeds with high bulk density or with large aggregates, the effect of the other variable was negligible. Increased bulk density delayed emergence mainly by decreasing the volume of voids in the soil. This elevated the interfacial stress to. the elongating coleoptile. The detrimental effect of increased aggregate size was mainly due to increase in the length of the path the coleoptile had to traverse to reach the soil surface, as it elongated through the inter-aggregate voids. Compaction of the seedbed to achieve the higher bulk densities in the coarser-aggregate seedbeds resulted in substantial breakdown of larger aggregates. Consequently, as the interfacial stress was increased by compaction, the path length was decreased, and both effects cancelled each other

Compact printed multiband antenna with independent setting suitable for fixed and reconfigurable wireless communication systems

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This paper presents the design of a low-profile compact printed antenna for fixed frequency and reconfigurable frequency bands. The antenna consists of a main patch, four sub-patches, and a ground plane to generate five frequency bands, at 0.92, 1.73, 1.98, 2.4, and 2.9 GHz, for different wireless systems. For the fixed-frequency design, the five individual frequency bands can be adjusted and set independently over the wide ranges of 18.78%, 22.75%, 4.51%, 11%, and 8.21%, respectively, using just one parameter of the antenna. By putting a varactor (diode) at each of the sub-patch inputs, four of the frequency bands can be controlled independently over wide ranges and the antenna has a reconfigurable design. The tunability ranges for the four bands of 0.92, 1.73, 1.98, and 2.9 GHz are 23.5%, 10.30%, 13.5%, and 3%, respectively. The fixed and reconfigurable designs are studied using computer simulation. For verification of simulation results, the two designs are fabricated and the prototypes are measured. The results show a good agreement between simulated and measured results

Synthesis and physico-chemical studies of a novel noncentrosymmetric heptacoordinated cadmium(II) compound containing a tripodal amine, CdCl2[N(C2H6N)3]2

A new noncentrosymmetric Cd(II) complex with thetripodal amine tris(2-aminoethyl)amine, CdCl2[N(C2H6N)3]2, has been prepared and characterized by single crystal X-ray diffraction, solid state NMR and IR spectroscopies. In the complex, the Cd(II) ion is surrounded by sevennitrogen atoms. The organic molecule acts as both a tri-and a tetradentate ligand. The cationic complexes are linked to each other forming layers parallel to the (a, b)plan. The Cl- counter ions occupy the cavities created inside these layers. The 13C CP-MAS NMR spectra are in agreement with the X-ray structure. DFT calculations allow the attribution of the carbon peaks to the differentatoms.The vibrational absorption bands were identified by infrared spectroscopy and DFT calculations allowed their attributions

Printed Multiband Antenna with Independent Setting Suitable for Fixed and Reconfigurable Wireless Communication Systems

published_or_final_versio

Degradation of human kininogens with the release of kinin peptides by extracellular proteinases of Candida spp.

The secretion of proteolytic enzymes by pathogenic microorganisms is one of the most successful strategies used by pathogens to colonize and infect the host organism. The extracellular microbial proteinases can seriously deregulate the homeostatic proteolytic cascades of the host, including the kinin-forming system, repeatedly reported to he activated during bacterial infection. The current study assigns a kinin-releasing activity to secreted proteinases of Candida spp. yeasts, the major fungal pathogens of humans. Of several Candida species studied, C. parapsilosis and C. albicans in their invasive filamentous forms are shown to produce proteinases which most effectively degrade proteinaceous kinin precursors, the kininogens. These enzymes, classified as aspartyl proteinases, have the highest kininogen-degrading activity at low pH (approx. 3.5), but the associated production of bradykinin-related peptides from a small fraction of kininogen molecules is optimal at neutral pH (6.5). The peptides effectively interact with cellular B2-type kinin receptors. Moreover, kinin-related peptides capable of interacting with inflammation-induced B1-type receptors are also formed, but with a reversed pH dependence. The presented variability of the potential extracellular kinin production by secreted aspartyl proteinases of Candida spp. is consistent with the known adaptability of these opportunistic pathogens to different niches in the host organism