79 research outputs found

    Allergy to propolis in Polish beekeepers

    Get PDF
    According to the literature propolis is a non-toxic and safe substance. However, propolis can induce allergy. Beekeepers may be the group most affected by contact allergy and propolis is an occupational contact allergen for them. To determine the prevalence of propolis contact allergy in beekeepers and theirs families and its possible association with other coexistent conditions. The questionnaire "Allergy to propolis among beekeepers" was distributed to beekeepers by hand through the Beekeepers Associations, especially the Provincial Association of Apiarists in Krakow. The study was conducted on adults of both genders who had given informed consent to participate in the study. The program Statistica was used for data management and statistical analysis. A total of 2540 questionnaires were distributed, including 1360 questionnaires from Malopolska region. Five hundred and fifty-eight questionnaires were returned, including 345 from Malopolska region. The response rate was 21.97% (25.4% Malopolska region). Among 558 beekeepers propolis contact allergy occurred in 17 cases (3.05%). Four hundred anf four of 558 beekeepers used propolis as a therapeutic agent. Eleven of 404 (2.72%) beekeepers reported propolis allergy. Only 5 beekeepers reported concomitant propolis allergy after contact with this substance during beekeeping and using propolis as a therapeutic agent. Among 2205 members of families who were using propolis only 14 patients (0.63%) reported propolis allergy. Allergy to propolis in Polish beekeepers does not seem to be a common phenomenon

    Finite VEVs from a Large Distance Vacuum Wave Functional

    Get PDF
    We show how to compute vacuum expectation values from derivative expansions of the vacuum wave functional. Such expansions appear to be valid only for slowly varying fields, but by exploiting analyticity in a complex scale parameter we can reconstruct the contribution from rapidly varying fields.Comment: 39 pages, 16 figures, LaTeX2e using package graphic

    Orthotopic liver transplantation for alcoholic liver disease

    Get PDF
    Alcohol abuse is the most common cause of end‐stage liver disease in the United States, but many transplant centers are unwilling to accept alcoholic patients because of their supposed potential for recidivism, poor compliance with the required immunosuppression regimen and resulting failure of the allograft. There is also concern that alcohol‐induced injury in other organs will preclude a good result. From July 1, 11982, to April 30, 1988, 73 patients received orthotopic liver transplants at the University of Pittsburgh for end‐stage alcoholic liver disease. Fifty‐two (71%) of these were alive at 25 ± 9 mo (mean ± S. D.) after transplantation, when a phone survey of these patients, their wives/husbands, and their physicians was performed to evaluate their subsequent use of alcohol, current medical condition and employment. Data obtained were compared with those for nonalcoholic patients selected as transplant controls. The recidivism rate has been 11.5%, with most patients drinking only socially. Fifty‐four percent of the survivors are employed, 21% classify themselves as homemakers and only 11 (21%) are unable to work. Twenty‐one patients died after transplantation; the most frequent cause of death was sepsis (43%), and intraoperative death was the next most common cause (28.6%). These data demonstrate that alcoholic patients can be transplanted successfully and achieve good health not significantly different from that of individuals transplanted for other causes. Thus orthotopic liver transplantation is a therapeutic option that should be considered for individuals with end‐stage alcoholic liver disease who desire such therapy. Copyright © 1990 American Association for the Study of Liver Disease

    Charge-density wave formation in Sr_{14}Cu_{24}O_{41}

    Full text link
    The electrodynamic response of the spin-ladder compound Sr14−x_{14-x}Cax_xCu24_{24}O41_{41} (x=0,3,9x=0, 3, 9) has been studied from radiofrequencies up to the infrared. At temperatures below 250 K a pronounced absorption peak appears around 12 cm−1^{-1} in Sr14_{14}Cu24_{24}O41_{41} for the radiation polarized along the chains/ladders (E∄c{\bf E}\parallel {\bf c}). In addition a strongly temperature dependent dielectric relaxation is observed in the kHz - MHz range. We explain this behavior by a charge density wave which develops in the ladders sub-system and produces a mode pinned at 12 cm−1^{-1}. With increasing Ca doping the mode shifts up in frequency and eventually disappears for x=9x=9 because the dimensionality of the system crosses over from one to two dimensions, giving way to the superconducting ground state under pressure.Comment: One name added to author list 4 pages, 2 figures, email: [email protected]

    Ordering phenomena in quasi one-dimensional organic conductors

    Full text link
    Low-dimensional organic conductors could establish themselves as model systems for the investigation of the physics in reduced dimensions. In the metallic state of a one-dimensional solid, Fermi-liquid theory breaks down and spin and charge degrees of freedom become separated. But the metallic phase is not stable in one dimension: as the temperature is reduced, the electronic charge and spin tend to arrange themselves in an ordered fashion due to strong correlations. The competition of the different interactions is responsible for which broken-symmetry ground state is eventually realized in a specific compound and which drives the system towards an insulating state. Here we review the various ordering phenomena and how they can be identified by optic and magnetic measurements. While the final results might look very similar in the case of a charge density wave and a charge-ordered metal, for instance, the physical cause is completely different. When density waves form, a gap opens in the density of states at the Fermi energy due to nesting of the one-dimension Fermi surface sheets. When a one-dimensional metal becomes a charge-ordered Mott insulator, on the other hand, the short-range Coulomb repulsion localizes the charge on the lattice sites and even causes certain charge patterns. We try to point out the similarities and conceptional differences of these phenomena and give an example for each of them. Particular emphasis will be put on collective phenomena which are inherently present as soon as ordering breaks the symmetry of the system.Comment: Review article Naturwissenschaften 200

    Gauge Invariant Higgs mass bounds from the Physical Effective Potential

    Get PDF
    We study a simplified version of the Standard Electroweak Model and introduce the concept of the physical gauge invariant effective potential in terms of matrix elements of the Hamiltonian in physical states. This procedure allows an unambiguous identification of the symmetry breaking order parameter and the resulting effective potential as the energy in a constrained state. We explicitly compute the physical effective potential at one loop order and improve it using the RG. This construction allows us to extract a reliable, gauge invariant bound on the Higgs mass by unambiguously obtaining the scale at which new physics should emerge to preclude vacuum instability. Comparison is made with popular gauge fixing procedures and an ``error'' estimate is provided between the Landau gauge fixed and the gauge invariant results.Comment: 23 pages, 2 figures, REVTE

    Signatures of polaronic excitations in quasi-one-dimensional LaTiO3.41_{3.41}

    Full text link
    The optical properties of quasi-one-dimensional metallic LaTiO3.41_{3.41} are studied for the polarization along the aa and bb axes. With decreasing temperature modes appear along both directions suggestive for a phase transition. The broadness of these modes along the conducting axis might be due to the coupling of the phonons to low-energy electronic excitations across an energy gap. We observe a pronounced midinfrared band with a temperature dependence consistent with (interacting) polaron models. The polaronic picture is corroborated by the presence of strong electron-phonon coupling and the temperature dependence of the dc conductivity.Comment: 5 pages, 5 figure

    Electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ

    Get PDF
    We study the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by means of density-functional band theory, Hubbard model calculations, and angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant quantitative and qualitative discrepancies to band theory. We demonstrate that the dispersive behavior as well as the temperature-dependence of the spectra can be consistently explained by the finite-energy physics of the one-dimensional Hubbard model at metallic doping. The model description can even be made quantitative, if one accounts for an enhanced hopping integral at the surface, most likely caused by a relaxation of the topmost molecular layer. Within this interpretation the ARPES data provide spectroscopic evidence for the existence of spin-charge separation on an energy scale of the conduction band width. The failure of the one-dimensional Hubbard model for the {\it low-energy} spectral behavior is attributed to interchain coupling and the additional effect of electron-phonon interaction.Comment: 18 pages, 9 figure

    The gauge invariant effective potential: equilibrium and non-equilibrium aspects

    Get PDF
    We propose a gauge invariant formulation of the effective potential in terms of a gauge invariant order parameter, for the Abelian Higgs model. The one-loop contribution at zero and finite temperature is computed explicitly, and the leading terms in the high temperature expansion are obtained. The result is contrasted to the effective potential obtained in several covariant gauge-fixing schemes, and the gauge invariant quantities that can be reliably extracted from these are identified. It is pointed out that the gauge invariant effective potential in the one-loop approximation is complex for {\em all values} of the order parameter between the maximum and the minimum of the tree level potential, both at zero and non-zero temperature. The imaginary part is related to long-wavelength instabilities towards phase separation. We study the real-time dynamics of initial states in the spinodal region, and relate the imaginary part of the effective potential to the growth rate of equal-time gauge invariant correlation functions in these states. We conjecture that the spinodal instabilities may play a role in non-equilibrium processes {\em inside} the nucleating bubbles if the transition is first order.Comment: 27 pages revtex 3.0, no figures; one reference adde
    • 

    corecore