22,309 research outputs found
Cough and dyspnea during bronchoconstriction: comparison of different stimuli
Abstract
Background
Bronchial challenge tests are used to evaluate bronchial responsiveness in diagnosis and follow-up of asthmatic patients. Challenge induced cough has increasingly been recognized as a valuable diagnostic tool. Various stimuli and protocols have been employed. The aim of this study was to compare cough and dyspnea intensity induced by different stimuli.
Methods
Twenty asthmatic patients underwent challenge tests with methacholine, bradykinin and exercise. Cough was counted during challenge tests. Dyspnea was assessed by modified Borg scale and visual analogue scale. Statistical comparisons were performed by linear mixed-effects model.
Results
For cough evaluation, bradykinin was the most potent trigger (p < 0.01). In terms of dyspnea measured by Borg scale, there were no differences among stimuli (p > 0.05). By visual analogue scale, bradykinin induced more dyspnea than other stimuli (p ≤ 0.04).
Conclusion
Bradykinin seems to be the most suitable stimulus for bronchial challenge tests intended for measuring cough in association with bronchoconstriction
Single Hole Green's Functions in Insulating Copper Oxides at Nonzero Temperature
We consider the single hole dynamics in a modified model at finite
temperature. The modified model includes a next nearest () and next-next
nearest () hopping. The model has been considered before in the zero
temperature limit to explain angle resolved photo-emission measurements. We
extend this consideration to the case of finite temperature where long-range
anti-ferromagnetic order is destroyed, using the self-consistent Born
approximation. The Dyson equation which relates the single hole Green's
functions for a fixed pseudo-spin and for fixed spin is derived. The Green's
function with fixed pseudo-spin is infrared stable but the Green's function
with fixed spin is close to an infrared divergency. We demonstrate how to
renormalize this Green's function in order to assure numerical convergence. At
non-zero temperature the quasi-particle peaks are found to shift down in energy
and to be broadened.Comment: 7 pages, RevTex, 5 Postscript figure
Spectral Function in Mott Insulating Surfaces
We show theoretically the fingerprints of short-range spiral magnetic
correlations in the photoemission spectra of the Mott insulating ground states
realized in the triangular silicon surfaces K/Si(111)-B and SiC(0001). The
calculated spectra present low energy features of magnetic origin with a
reduced dispersion ~10-40 meV compared with the center-of-mass spectra
bandwidth ~0.2-0:3 eV. Remarkably, we find that the quasiparticle signal
survives only around the magnetic Goldstone modes. Our findings would position
these silicon surfaces as new candidates to investigate non-conventional
quasiparticle excitations.Comment: 5 pages, 4 figures. To be published in Journal of Physics: Condensed
Matte
Hole photoproduction in insulating copper oxide
Basing on t-J model we calculate the k-dependence of a single hole
photoproduction probability for CuO2 plane at zero doping. We also discuss the
radiation of spin-waves which can substantially deform the shape of
photoemission spectra.Comment: latex 8 pages, 3 figure
Laboratory animals and respiratory allergies: The prevalence of allergies among laboratory animal workers and the need for prophylaxis
OBJECTIVE: Subjects exposed to laboratory animals are at a heightened risk of developing respiratory and allergic diseases. These diseases can be prevented by simple measures such as the use of personal protective equipment. We report here the primary findings of the Laboratory Animals and Respiratory Allergies Study regarding the prevalence of allergic diseases among laboratory animal workers, the routine use of preventive measures in laboratories and animal facilities, and the need for prevention programs. METHODS: Animal handlers and non-animal handlers from 2 Brazilian universities (University of São Paulo and State University of Campinas) answered specific questionnaires to assess work conditions and symptoms. These subjects also underwent spirometry, a bronchial challenge test with mannitol, and skin prick tests for 11 common allergens and 5 occupational allergens (rat, mouse, guinea pig, hamster, and rabbit). RESULTS: Four hundred fifty-five animal handlers (32±10 years old [mean±SD], 209 men) and 387 non-animal handlers (33±11 years old, 121 men) were evaluated. Sensitization to occupational allergens was higher among animal handlers (16%) than non-animal handlers (3%,
Normal Fermi Liquid Behavior of Quasiholes in the Spin-Polaron Model for Copper Oxides
Based on the t-J model and the self-consistent Born approximation, the
damping of quasiparticle hole states near the Fermi surface is calculated in a
low doping regime. Renormalization of spin-wave excitations due to hole doping
is taken into account. The damping is shown to be described by a familiar form
characteristic of the 2-dimensional
Fermi liquid, in contrast with the earlier statement reported by Li and Gong
[Phys. Rev. B {\bf 51}, 6343 (1995)] on the marginal Fermi liquid behavior of
quasiholes
Hole-hole superconducting pairing in the t-J model induced by spin-wave exchange
We study numerically the hole pairing induced by spin-wave exchange. The
contact hole-hole interaction is taken into account as well. It is assumed that
antiferromagnetic order is preserved at all scales relevant to pairing. The
strongest pairing is obtained for the d-wave symmetry of the gap. Dependence of
the value of the gap on hole concentration and temperature is presented. For
the critical temperature we obtain Tc about 100 K at the hole concentration
delta = 0.2-0.3.Comment: replaced with a revised version to appear in PRB, 6 pages, REVTeX
3.0, figures not change
Identificação de germoplasma e desenvolvimento de cultivares de arroz com elevados teores de ferro e zinco.
Objetivando disseminar o uso de cultivares de arroz de terras altas mais ricas em ferro e zinco foram avaliadas 194 das mais de 3.600 variedades locais coletadas no Brasil nos últimos 30 anos pela Empresa Brasileira de Pesquisa Agropecuária (Embrapa). Zebu Ligeiro e Chatão Branco, mais ricas em zinco e ferro, respectivamente, estão em processo de disseminação e avaliação, de forma participativa, junto a agricultores familiares do Maranhão, nos municípios de Miranda do Norte, Vargem Grande, Chapadinha e Brejo, em estreita colaboração com a Agência de Extensão Rural e Pesquisa do Estado do Maranhão (AGERP).Resumo também em inglês
Green mecanochemical process for carbon nanotubes coating with humic acid: application and ecotoxicity evaluation.
Nanomaterials (NM) are promising for environmental remediation due to their unreleased properties such as high surface area and reactivity. Chemical oxidations (H2SO4/HNO3) have been applied to carbon NM in order to favor their application, but these are expensive and hazardous. In this work, industrial grade multiwalled carbon nanotubes (raw-MWCNT) were coated with humic acid (HA) by a ball milling processing (solid state). The aim was to apply a green mechanochemical process to improve the colloidal stability of MWCNTs and their removal capacity of metals. The HA-MWCNT complex was studied by atomic force microscope (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), dynamic light scattering (DLS), electrophoretic light scattering (ELS) and ultraviolet-visible spectroscopy (UV-Vis). Cu2+ sorption from water by HA-MWCNT, MWCNT-COOH and milledMWCNT were compared. Acute bioassays (96h) were performed with Daphnia magna exposed to 0.0; 0.1; 1.0; 5.0 and 10.0 mg/L of HA-MWCNT. Our results showed that the coating process enhanced the zeta potential of raw-MWCNT of -25.4±0.2 mV to -37.4±0.7 mV and reduced their hydrodynamic diameter of 393.2±27.3 nm to 212.5±5.6 nm in ultrapure water. AFM images of HA-MWCNT showed that it has an irregular surface, due to the humic acid coating. The complex was 4 times (84±1.8%) more efficient to remove Cu2+ than MWCNTCOOH (20.0±1.4%) and 11 times compared to milled-MWCNT (7.6±3.1%). The increases in Oxygen and the reductions in Carbon on surface of HA-MWCNT relative to raw-MWCNT and milled-MWCNT indicated the introduction of functional oxygenated groups on MWCNT. The HA-MWCNT did not show acute toxicity against D. magna. These results suggest that the coating changes the MWCNT surface, resulting in a material with potential to metal remediation, prepared without oxidizing acids and that did not show toxicity on D. magna
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