16 results on '"Szücs, T."'
Search Results
2. Proton-Capture Rates on Carbon Isotopes and Their Impact on the Astrophysical ^{12}C/^{13}C Ratio.
- Author
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Skowronski J, Boeltzig A, Ciani GF, Csedreki L, Piatti D, Aliotta M, Ananna C, Barile F, Bemmerer D, Best A, Broggini C, Bruno CG, Caciolli A, Campostrini M, Cavanna F, Colombetti P, Compagnucci A, Corvisiero P, Davinson T, Depalo R, Di Leva A, Elekes Z, Ferraro F, Formicola A, Fülöp Z, Gervino G, Gesuè RM, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Lugaro M, Marigo P, Masha E, Menegazzo R, Paticchio V, Perrino R, Prati P, Rapagnani D, Rigato V, Schiavulli L, Sidhu RS, Straniero O, Szücs T, and Zavatarelli S
- Abstract
The ^{12}C/^{13}C ratio is a significant indicator of nucleosynthesis and mixing processes during hydrogen burning in stars. Its value mainly depends on the relative rates of the ^{12}C(p,γ)^{13}N and ^{13}C(p,γ)^{14}N reactions. Both reactions have been studied at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy down to the lowest energies to date (E_{c.m.}=60 keV) reaching for the first time the high energy tail of hydrogen burning in the shell of giant stars. Our cross sections, obtained with both prompt γ-ray detection and activation measurements, are the most precise to date with overall systematic uncertainties of 7%-8%. Compared with most of the literature, our results are systematically lower, by 25% for the ^{12}C(p,γ)^{13}N reaction and by 30% for ^{13}C(p,γ)^{14}N. We provide the most precise value up to now of 3.6±0.4 in the 20-140 MK range for the lowest possible ^{12}C/^{13}C ratio that can be produced during H burning in giant stars.
- Published
- 2023
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3. Direct Measurement of the ^{13}C(α,n)^{16}O Cross Section into the s-Process Gamow Peak.
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Ciani GF, Csedreki L, Rapagnani D, Aliotta M, Balibrea-Correa J, Barile F, Bemmerer D, Best A, Boeltzig A, Broggini C, Bruno CG, Caciolli A, Cavanna F, Chillery T, Colombetti P, Corvisiero P, Cristallo S, Davinson T, Depalo R, Di Leva A, Elekes Z, Ferraro F, Fiore E, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Lugaro M, Marigo P, Masha E, Menegazzo R, Mossa V, Pantaleo FR, Paticchio V, Perrino R, Piatti D, Prati P, Schiavulli L, Stöckel K, Straniero O, Szücs T, Takács MP, Terrasi F, Vescovi D, and Zavatarelli S
- Abstract
One of the main neutron sources for the astrophysical s process is the reaction ^{13}C(α,n)^{16}O, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model the nucleosynthesis during this process the reaction cross section needs to be known in the 150-230 keV energy window (Gamow peak). At these sub-Coulomb energies, cross section direct measurements are severely affected by the low event rate, making us rely on input from indirect methods and extrapolations from higher-energy direct data. This leads to an uncertainty in the cross section at the relevant energies too high to reliably constrain the nuclear physics input to s-process calculations. We present the results from a new deep-underground measurement of ^{13}C(α,n)^{16}O, covering the energy range 230-300 keV, with drastically reduced uncertainties over previous measurements and for the first time providing data directly inside the s-process Gamow peak. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular, the two radioactive nuclei ^{60}Fe and ^{205}Pb, as well as ^{152}Gd.
- Published
- 2021
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4. The baryon density of the Universe from an improved rate of deuterium burning.
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Mossa V, Stöckel K, Cavanna F, Ferraro F, Aliotta M, Barile F, Bemmerer D, Best A, Boeltzig A, Broggini C, Bruno CG, Caciolli A, Chillery T, Ciani GF, Corvisiero P, Csedreki L, Davinson T, Depalo R, Di Leva A, Elekes Z, Fiore EM, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Kievsky A, Kochanek I, Lugaro M, Marcucci LE, Mangano G, Marigo P, Masha E, Menegazzo R, Pantaleo FR, Paticchio V, Perrino R, Piatti D, Pisanti O, Prati P, Schiavulli L, Straniero O, Szücs T, Takács MP, Trezzi D, Viviani M, and Zavatarelli S
- Abstract
Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN)
1,2 . Among the light elements produced during BBN1,2 , deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density and also depends on the number of neutrino species permeating the early Universe. Although astronomical observations of primordial deuterium abundance have reached percent accuracy3 , theoretical predictions4-6 based on BBN are hampered by large uncertainties on the cross-section of the deuterium burning D(p,γ)3 He reaction. Here we show that our improved cross-sections of this reaction lead to BBN estimates of the baryon density at the 1.6 percent level, in excellent agreement with a recent analysis of the cosmic microwave background7 . Improved cross-section data were obtained by exploiting the negligible cosmic-ray background deep underground at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Laboratori Nazionali del Gran Sasso (Italy)8,9 . We bombarded a high-purity deuterium gas target10 with an intense proton beam from the LUNA 400-kilovolt accelerator11 and detected the γ-rays from the nuclear reaction under study with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances to probe the physics of the early Universe.- Published
- 2020
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5. Successful Prediction of Total α-Induced Reaction Cross Sections at Astrophysically Relevant Sub-Coulomb Energies Using a Novel Approach.
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Mohr P, Fülöp Z, Gyürky G, Kiss GG, and Szücs T
- Abstract
The prediction of stellar (γ,α) reaction rates for heavy nuclei is based on the calculation of (α,γ) cross sections at sub-Coulomb energies. These rates are essential for modeling the nucleosynthesis of so-called p nuclei. The standard calculations in the statistical model show a dramatic sensitivity to the chosen α-nucleus potential. The present study explains the reason for this dramatic sensitivity which results from the tail of the imaginary α-nucleus potential in the underlying optical model calculation of the total reaction cross section. As an alternative to the optical model, a simple barrier transmission model is suggested. It is shown that this simple model in combination with a well-chosen α-nucleus potential is able to predict total α-induced reaction cross sections for a wide range of heavy target nuclei above A≳150 with uncertainties below a factor of 2. The new predictions from the simple model do not require any adjustment of parameters to experimental reaction cross sections whereas in previous statistical model calculations all predictions remained very uncertain because the parameters of the α-nucleus potential had to be adjusted to experimental data. The new model allows us to predict the reaction rate of the astrophysically important ^{176}W(α,γ)^{180}Os reaction with reduced uncertainties, leading to a significantly lower reaction rate at low temperatures. The new approach could also be validated for a broad range of target nuclei from A≈60 up to A≳200.
- Published
- 2020
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6. Half-life measurement of 65 Ga with γ-spectroscopy.
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Gyürky G, Halász Z, Kiss GG, Szücs T, and Fülöp Z
- Abstract
The literature half-life value of
65 Ga is based on only one experiment carried out more than 60 years ago and it has a relatively large uncertainty. In the present work this half-life is determined based on the counting of the γ-rays following the β-decay of65 Ga. Our new recommended half-life is t1/2 = (15.133 ± 0.028) min which is in agreement with the literature value but almost one order of magnitude more precise., (Copyright © 2019 Elsevier Ltd. All rights reserved.)- Published
- 2019
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7. Approaching the Gamow Window with Stored Ions: Direct Measurement of ^{124}Xe(p,γ) in the ESR Storage Ring.
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Glorius J, Langer C, Slavkovská Z, Bott L, Brandau C, Brückner B, Blaum K, Chen X, Dababneh S, Davinson T, Erbacher P, Fiebiger S, Gaßner T, Göbel K, Groothuis M, Gumberidze A, Gyürky G, Heil M, Hess R, Hensch R, Hillmann P, Hillenbrand PM, Hinrichs O, Jurado B, Kausch T, Khodaparast A, Kisselbach T, Klapper N, Kozhuharov C, Kurtulgil D, Lane G, Lederer-Woods C, Lestinsky M, Litvinov S, Litvinov YA, Löher B, Nolden F, Petridis N, Popp U, Rauscher T, Reed M, Reifarth R, Sanjari MS, Savran D, Simon H, Spillmann U, Steck M, Stöhlker T, Stumm J, Surzhykov A, Szücs T, Nguyen TT, Taremi Zadeh A, Thomas B, Torilov SY, Törnqvist H, Träger M, Trageser C, Trotsenko S, Varga L, Volknandt M, Weick H, Weigand M, Wolf C, Woods PJ, and Xing YM
- Abstract
We report the first measurement of low-energy proton-capture cross sections of ^{124}Xe in a heavy-ion storage ring. ^{124}Xe^{54+} ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. The ^{125}Cs reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.
- Published
- 2019
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8. Direct Capture Cross Section and the E_{p}=71 and 105 keV Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction.
- Author
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Ferraro F, Takács MP, Piatti D, Cavanna F, Depalo R, Aliotta M, Bemmerer D, Best A, Boeltzig A, Broggini C, Bruno CG, Caciolli A, Chillery T, Ciani GF, Corvisiero P, Davinson T, D'Erasmo G, Di Leva A, Elekes Z, Fiore EM, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Karakas A, Kochanek I, Lugaro M, Marigo P, Menegazzo R, Mossa V, Pantaleo FR, Paticchio V, Perrino R, Prati P, Schiavulli L, Stöckel K, Straniero O, Szücs T, Trezzi D, and Zavatarelli S
- Abstract
The ^{22}Ne(p,γ)^{23}Na reaction, part of the neon-sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. Its rate is controlled by a number of low-energy resonances and a slowly varying nonresonant component. Three new resonances at E_{p}=156.2, 189.5, and 259.7 keV have recently been observed and confirmed. However, significant uncertainty on the reaction rate remains due to the nonresonant process and to two suggested resonances at E_{p}=71 and 105 keV. Here, new ^{22}Ne(p,γ)^{23}Na data with high statistics and low background are reported. Stringent upper limits of 6×10^{-11} and 7×10^{-11} eV (90% confidence level), respectively, are placed on the two suggested resonances. In addition, the off-resonant S factor has been measured at unprecedented low energy, constraining the contributions from a subthreshold resonance and the direct capture process. As a result, at a temperature of 0.1 GK the error bar of the ^{22}Ne(p,γ)^{23}Na rate is now reduced by 3 orders of magnitude.
- Published
- 2018
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9. Erratum: Three New Low-Energy Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction [Phys. Rev. Lett. 115, 252501 (2015)].
- Author
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Cavanna F, Depalo R, Aliotta M, Anders M, Bemmerer D, Best A, Boeltzig A, Broggini C, Bruno CG, Caciolli A, Corvisiero P, Davinson T, di Leva A, Elekes Z, Ferraro F, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Menegazzo R, Mossa V, Pantaleo FR, Prati P, Scott DA, Somorjai E, Straniero O, Strieder F, Szücs T, Takács MP, and Trezzi D
- Abstract
This corrects the article DOI: 10.1103/PhysRevLett.115.252501.
- Published
- 2018
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10. Improved Direct Measurement of the 64.5 keV Resonance Strength in the ^{17}O(p,α)^{14}N Reaction at LUNA.
- Author
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Bruno CG, Scott DA, Aliotta M, Formicola A, Best A, Boeltzig A, Bemmerer D, Broggini C, Caciolli A, Cavanna F, Ciani GF, Corvisiero P, Davinson T, Depalo R, Di Leva A, Elekes Z, Ferraro F, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Menegazzo R, Mossa V, Pantaleo FR, Piatti D, Prati P, Somorjai E, Straniero O, Strieder F, Szücs T, Takács MP, and Trezzi D
- Abstract
The ^{17}O(p,α)^{14}N reaction plays a key role in various astrophysical scenarios, from asymptotic giant branch stars to classical novae. It affects the synthesis of rare isotopes such as ^{17}O and ^{18}F, which can provide constraints on astrophysical models. A new direct determination of the E_{R}=64.5 keV resonance strength performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) accelerator has led to the most accurate value to date ωγ=10.0±1.4_{stat}±0.7_{syst} neV, thanks to a significant background reduction underground and generally improved experimental conditions. The (bare) proton partial width of the corresponding state at E_{x}=5672 keV in ^{18}F is Γ_{p}=35±5_{stat}±3_{syst} neV. This width is about a factor of 2 higher than previously estimated, thus leading to a factor of 2 increase in the ^{17}O(p, α)^{14}N reaction rate at astrophysical temperatures relevant to shell hydrogen burning in red giant and asymptotic giant branch stars. The new rate implies lower ^{17}O/^{16}O ratios, with important implications on the interpretation of astrophysical observables from these stars.
- Published
- 2016
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11. Three New Low-Energy Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction.
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Cavanna F, Depalo R, Aliotta M, Anders M, Bemmerer D, Best A, Boeltzig A, Broggini C, Bruno CG, Caciolli A, Corvisiero P, Davinson T, di Leva A, Elekes Z, Ferraro F, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Menegazzo R, Mossa V, Pantaleo FR, Prati P, Scott DA, Somorjai E, Straniero O, Strieder F, Szücs T, Takács MP, and Trezzi D
- Abstract
The ^{22}Ne(p,γ)^{23}Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle affects the synthesis of the elements between ^{20}Ne and ^{27}Al in asymptotic giant branch stars and novae. The ^{22}Ne(p,γ)^{23}Na reaction rate is very uncertain because of a large number of unobserved resonances lying in the Gamow window. At proton energies below 400 keV, only upper limits exist in the literature for the resonance strengths. Previous reaction rate evaluations differ by large factors. In the present work, the first direct observations of the ^{22}Ne(p,γ)^{23}Na resonances at 156.2, 189.5, and 259.7 keV are reported. Their resonance strengths are derived with 2%-7% uncertainty. In addition, upper limits for three other resonances are greatly reduced. Data are taken using a windowless ^{22}Ne gas target and high-purity germanium detectors at the Laboratory for Underground Nuclear Astrophysics in the Gran Sasso laboratory of the National Institute for Nuclear Physics, Italy, taking advantage of the ultralow background observed deep underground. The new reaction rate is a factor of 20 higher than the recent evaluation at a temperature of 0.1 GK, relevant to nucleosynthesis in asymptotic giant branch stars.
- Published
- 2015
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12. First direct measurement of the 2H(α,γ)6Li cross section at big bang energies and the primordial lithium problem.
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Anders M, Trezzi D, Menegazzo R, Aliotta M, Bellini A, Bemmerer D, Broggini C, Caciolli A, Corvisiero P, Costantini H, Davinson T, Elekes Z, Erhard M, Formicola A, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Junker M, Lemut A, Marta M, Mazzocchi C, Prati P, Rossi Alvarez C, Scott DA, Somorjai E, Straniero O, and Szücs T
- Abstract
Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.
- Published
- 2014
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13. First direct measurement of the 17O(p,γ)18F reaction cross section at Gamow energies for classical novae.
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Scott DA, Caciolli A, Di Leva A, Formicola A, Aliotta M, Anders M, Bemmerer D, Broggini C, Campeggio M, Corvisiero P, Elekes Z, Fülöp Z, Gervino G, Guglielmetti A, Gustavino C, Gyürky G, Imbriani G, Junker M, Laubenstein M, Menegazzo R, Marta M, Napolitani E, Prati P, Rigato V, Roca V, Somorjai E, Salvo C, Straniero O, Strieder F, Szücs T, Terrasi F, and Trezzi D
- Abstract
Classical novae are important contributors to the abundances of key isotopes, such as the radioactive (18)F, whose observation by satellite missions could provide constraints on nucleosynthesis models in novae. The (17)O(p,γ)(18)F reaction plays a critical role in the synthesis of both oxygen and fluorine isotopes, but its reaction rate is not well determined because of the lack of experimental data at energies relevant to novae explosions. In this study, the reaction cross section has been measured directly for the first time in a wide energy range E(c.m.)~/= 200-370 keV appropriate to hydrogen burning in classical novae. In addition, the E(c.m.)=183 keV resonance strength, ωγ=1.67±0.12 μeV, has been measured with the highest precision to date. The uncertainty on the (17)O(p,γ)(18)F reaction rate has been reduced by a factor of 4, thus leading to firmer constraints on accurate models of novae nucleosynthesis.
- Published
- 2012
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14. Half-life measurement of 66Ga with γ-spectroscopy.
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Gyürky G, Farkas J, Halász Z, and Szücs T
- Subjects
- Half-Life, Radiation Dosage, Algorithms, Gallium Radioisotopes analysis, Gallium Radioisotopes chemistry, Radiometry methods, Spectrometry, Gamma methods
- Abstract
The half-life of (66)Ga, an isotope very important for high-energy efficiency calibration of γ-detectors, has been measured using γ-spectroscopy. In order to reduce systematic uncertainties, different source production methods and γ-counting conditions have been applied. A half-life value of t(1/2)=(9.312±0.032)h has been obtained in agreement with a recent measurement but in contradiction with some of the earlier results., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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15. [Surgical management of thrombosis of the inferior vena cava].
- Author
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Gyurkó G, Szücs T, Ezsely F, and Scherfel T
- Subjects
- Adult, Female, Humans, Male, Middle Aged, Radiography, Thrombophlebitis diagnostic imaging, Vena Cava, Inferior diagnostic imaging, Thrombophlebitis surgery, Vena Cava, Inferior surgery
- Published
- 1982
16. Immunopathologic role of proteoglycan antigens in rheumatoid joint disease.
- Author
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Glant T, Csongor J, and Szücs T
- Subjects
- Adult, Aged, Cartilage, Articular immunology, Cell Movement, Female, Humans, Knee, Lymphocyte Activation, Male, Middle Aged, Spondylitis, Ankylosing immunology, Synovitis immunology, Arthritis, Rheumatoid immunology, Proteoglycans immunology
- Abstract
Cell-mediated immunity to proteoglycan antigens was assessed by leucocyte migration inhibition and by lymphocyte stimulation tests in patients with rheumatoid arthritis or with ankylosing spondylarthritis, in patients with relapsing synovitis after a single trauma to their knee joints, and in healthy donors. Both tests revealed a sensitization in most of the patients examined with various proteoglycan antigens derived from human cartilaginous tissues, rheumatoid synovial fluid, and species-common antigen of bovine nasal cartilage. Antibodies against proteoglycan antigens of human articular cartilage were detected by solid-phase radioimmunoassay in eleven out of twenty-nine sera from patients with rheumatoid arthritis and in four out of six rheumatoid synovial fluids. The results suggest that the cartilage antigenic components released by an inflammatory process or trauma may trigger a vicious circle of chronic inflammation and joint destruction.
- Published
- 1980
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