80 research outputs found
Allergy to propolis in Polish beekeepers
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
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
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Medical studentsâ characteristics as predictors of career practice location: retrospective cohort study tracking graduates of Nepalâs first medical college
Objective: To determine, in one low income country (Nepal), which characteristics of medical students are associated with graduate doctors staying to practise in the country or in its rural areas. Design: Observational cohort study. Setting: Medical college registry, with internet, phone, and personal follow-up of graduates. Participants: 710 graduate doctors from the first 22 classes (1983-2004) of Nepalâs first medical college, the Institute of Medicine. Main outcome measures: Career practice location (foreign or in Nepal; in or outside of the capital city Kathmandu) compared with certain pre-graduation characteristics of medical student. Results: 710 (97.7%) of the 727 graduates were located: 193 (27.2%) were working in Nepal in districts outside the capital city Kathmandu, 261 (36.8%) were working in Kathmandu, and 256 (36.1%) were working in foreign countries. Of 256 working abroad, 188 (73%) were in the United States. Students from later graduating classes were more likely to be working in foreign countries. Those with pre-medical education as paramedics were twice as likely to be working in Nepal and 3.5 times as likely to be in rural Nepal, compared with students with a college science background. Students who were academically in the lower third of their medical school class were twice as likely to be working in rural Nepal as those from the upper third. In a regression analysis adjusting for all variables, paramedical background (odds ratio 4.4, 95% confidence interval 1.7 to 11.6) was independently associated with a doctor remaining in Nepal. Rural birthplace (odds ratio 3.8, 1.3 to 11.5) and older age at matriculation (1.1, 1.0 to 1.2) were each independently associated with a doctor working in rural Nepal. Conclusions: A cluster of medical studentsâ characteristics, including paramedical background, rural birthplace, and lower academic rank, was associated with a doctor remaining in Nepal and with working outside the capital city of Kathmandu. Policy makers in medical education who are committed to producing doctors for underserved areas of their country could use this evidence to revise their entrance criteria for medical school
Orthotopic liver transplantation for alcoholic liver disease
Alcohol abuse is the most common cause of endâstage 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 alcoholâinduced 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 endâstage alcoholic liver disease. Fiftyâtwo (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. Fiftyâfour percent of the survivors are employed, 21% classify themselves as homemakers and only 11 (21%) are unable to work. Twentyâone 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 endâstage 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}
The electrodynamic response of the spin-ladder compound
SrCaCuO () has been studied from
radiofrequencies up to the infrared. At temperatures below 250 K a pronounced
absorption peak appears around 12 cm in SrCuO for
the radiation polarized along the chains/ladders ().
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.
With increasing Ca doping the mode shifts up in frequency and eventually
disappears for 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
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
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 LaTiO
The optical properties of quasi-one-dimensional metallic LaTiO are
studied for the polarization along the and 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
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
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
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