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1.
Phys Rev Lett ; 127(8): 082501, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34477443

RESUMO

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f_{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

2.
Rev. Fac. Odontol. (B.Aires) ; 34(76): 37-42, 2019. ilus, tab, graf
Artigo em Espanhol | LILACS | ID: biblio-1102537

RESUMO

Los objetivos de este trabajo fueron conocer la percepción de estudiantes y docentes sobre la implementación de la modalidad de clases expositivas on-line, estimar la frecuencia y oportunidad de acceso por parte de los alumnos y comparar los resultados obtenidos en las calificaciones finales obtenidas con la modalidad teórico presencial y la on-line. El recurso resultó positivo para el 80,62% y 73,33% de alumnos y docentes respectivamente. Los primeros ingresaron cada uno un promedio de 2,75±1,45 veces a cada uno de los 15 módulos y el 60.45% lo hizo 15 días antes del examen. No hubo diferencias entre las calificaciones obtenidas entre dos cohortes que utilizaron las diferentes modalidades. Se concluyó que la modalidad on-line con clase de repaso presencial fue percibida como apropiada y con contenidos relevantes. Fue utilizada por los estudiantes como una herramienta de consulta, con amplia flexibilidad horaria y en reiteradas oportunidades, sin restarle horas a la atención de pacientes (AU)


Assuntos
Humanos , Masculino , Feminino , Adulto , Estudantes de Odontologia , Odontopediatria/educação , Aula , Educação a Distância , Argentina , Faculdades de Odontologia , Epidemiologia Descritiva , Estudos Transversais , Estudos Prospectivos , Tecnologia da Informação
3.
Phys Rev Lett ; 119(11): 112002, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28949229

RESUMO

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/c π^{-} beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c^{2} and 8.5 GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

4.
Phys Rev Lett ; 115(8): 082001, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26340182

RESUMO

The COMPASS Collaboration at CERN has measured diffractive dissociation of 190 GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow peak is observed in the f0(980)π channel with spin, parity and C-parity quantum numbers J(PC)=1(++). We present a resonance-model study of a subset of the spin-density matrix selecting 3π states with J(PC)=2(++) and 4(++) decaying into ρ(770)π and with J(PC)=1(++) decaying into f0(980)π. We identify a new a1 meson with mass (1414(-13)(+15)) MeV/c2 and width (153(-23)(+8)) MeV/c2. Within the final states investigated in our analysis, we observe the new a1(1420) decaying only into f0(980)π, suggesting its exotic nature.

5.
Phys Rev Lett ; 114(6): 062002, 2015 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-25723208

RESUMO

The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015 (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4) fm(3) under the assumption α(π)=-ß(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

6.
Phys Rev Lett ; 108(19): 192001, 2012 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-23003028

RESUMO

The COMPASS Collaboration at CERN has investigated the π- γ → π- π- π+ reaction at center-of-momentum energy below five pion masses, sqrt[s]<5m(π), embedded in the Primakoff reaction of 190 GeV pions impinging on a lead target. Exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, t'<0.001 GeV2/c2. Using partial-wave analysis techniques, the scattering intensity of Coulomb production described in terms of chiral dynamics and its dependence on the 3π-invariant mass m(3π)=sqrt[s] were extracted. The absolute cross section was determined in seven bins of sqrt[s] with an overall precision of 20%. At leading order, the result is found to be in good agreement with the prediction of chiral perturbation theory over the whole energy range investigated.

7.
Phys Rev Lett ; 104(24): 241803, 2010 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-20867295

RESUMO

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1 GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66 GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0)) MeV/c2 and a width of (269±21(-64)(+42)) MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.

9.
Bol. Asoc. Argent. Odontol. Niños ; 36(1/2): 8-10, mar.-jun. 2007. ilus
Artigo em Espanhol | LILACS | ID: lil-467717

RESUMO

La dentinogénesis imperfecta (DI) es descripta como una anomalía congénita de estructura, que puede afectar a una o a ambas denticiones. Se caracteriza por la presencia de piezas dentarias translúcidas u opalescentes, con una dentina irregular, atubular y fibrosa de menor concentración mineral, que oblitera la cámara pulpar y los conductos radiculares. El esmalte es normal química e histológicamente, pero tiende a desprenderse de la dentina, que se desgasta con extraordinaria rapidez. Puede presentarse como una alteración aislada o asociada a un síndrome congénito denominado osteogénesis imperfecta (OI) caracterizado por fragilidad ósea. El propósito de este trabajo es presentar el reporte de una paciente de 5 años derivada con diagnóstico de OI y la rehabilitación de las piezas primarias afectadas, para establecer la función y la estética perdidas


Assuntos
Humanos , Feminino , Pré-Escolar , Dentinogênese Imperfeita/etiologia , Esmalte Dentário/patologia , Osteogênese Imperfeita/complicações , Coroas , Facetas Dentárias , Fluoretos Tópicos/administração & dosagem , Higiene Bucal/educação , Planejamento de Assistência ao Paciente , Resinas Compostas/uso terapêutico
10.
Bol. Asoc. Argent. Odontol. Niños ; 36(1/2): 8-10, mar.-jun. 2007. ilus
Artigo em Espanhol | BINACIS | ID: bin-120730

RESUMO

La dentinogénesis imperfecta (DI) es descripta como una anomalía congénita de estructura, que puede afectar a una o a ambas denticiones. Se caracteriza por la presencia de piezas dentarias translúcidas u opalescentes, con una dentina irregular, atubular y fibrosa de menor concentración mineral, que oblitera la cámara pulpar y los conductos radiculares. El esmalte es normal química e histológicamente, pero tiende a desprenderse de la dentina, que se desgasta con extraordinaria rapidez. Puede presentarse como una alteración aislada o asociada a un síndrome congénito denominado osteogénesis imperfecta (OI) caracterizado por fragilidad ósea. El propósito de este trabajo es presentar el reporte de una paciente de 5 años derivada con diagnóstico de OI y la rehabilitación de las piezas primarias afectadas, para establecer la función y la estética perdidas (AU)


Assuntos
Humanos , Feminino , Pré-Escolar , Osteogênese Imperfeita/complicações , Dentinogênese Imperfeita/etiologia , Esmalte Dentário/patologia , Planejamento de Assistência ao Paciente , Coroas , Fluoretos Tópicos/administração & dosagem , Higiene Bucal/educação , Facetas Dentárias , Resinas Compostas/uso terapêutico
11.
Phys Rev Lett ; 94(20): 202002, 2005 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-16090237

RESUMO

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

12.
Nutr Cancer ; 27(1): 80-3, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-8970187

RESUMO

In a randomized controlled clinical trial, 14 patients requiring resection of tumors were divided in two groups: one group was anesthetized with nitrous oxide [67% N2O-33% O2 (vol/vol)] and the other with propofol. Two other groups of subjects were studied: a group of patients that was undergoing orthopedic procedures and was anesthetized with nitrous oxide [67% N2O-33% O2 (vol/vol)] and a control group (fasted for 10 hrs and no anesthesia). In patients requiring resection of tumors, the blood L-methionine concentration was significantly lower and the blood amino acid pattern was significantly affected after the administration of nitrous oxide (120-310 mins) compared with values after the induction of anesthesia and before surgery. The administration of propofol (120-240 mins) did not produce any of these changes. No patients required blood transfusion during surgery, and the patients had not previously been treated with cancer chemotherapeutic agents. The administration of nitrous oxide (60-150 mins) to patients undergoing orthopedic procedures did not affect blood L-methionine. It is concluded that the administration of nitrous oxide to cancer-bearing patients, but not to those undergoing orthopedic surgery, produced major changes in amino acid metabolism; therefore, consideration should be given to the avoidance of exposure of cancer patients to nitrous oxide.


Assuntos
Aminoácidos/metabolismo , Anestésicos Inalatórios/farmacologia , Anestésicos Intravenosos/farmacologia , Neoplasias Brônquicas/metabolismo , Glioblastoma/metabolismo , Neoplasias Laríngeas/metabolismo , Óxido Nitroso/farmacologia , Propofol/farmacologia , Neoplasias Gástricas/metabolismo , Neoplasias Testiculares/metabolismo , Aminoácidos/sangue , Neoplasias Brônquicas/sangue , Neoplasias Brônquicas/cirurgia , Fraturas Ósseas/sangue , Fraturas Ósseas/metabolismo , Fraturas Ósseas/cirurgia , Glioblastoma/sangue , Glioblastoma/cirurgia , Humanos , Neoplasias Laríngeas/sangue , Neoplasias Laríngeas/cirurgia , Masculino , Ortopedia , Neoplasias Gástricas/sangue , Neoplasias Gástricas/cirurgia , Neoplasias Testiculares/sangue , Neoplasias Testiculares/cirurgia , Fatores de Tempo
13.
Campinas; s.n; 1997. x p.
Tese em Português | Index Psicologia - Teses | ID: pte-30109

RESUMO

O objetivo desta pesquisa foi diagnosticar as variáveis que influenciaram o clima criativo e a inovação dentro das organizações públicas e particulares; considerando como organizações, tanto a escola como a empresa. A amostra foi composta por 80 sujeitos, sendo 40 da organização educacional (pública e particular) estando estas instituições situadas na cidade de Campinas. O instrumento utilizado foi o 'Questionário de Clima e Criatividade', contendo 50 questões. Foi efetuada a Análise de Variância para comparação entre as quatro organizações, nas seguintes variáveis; Desafio e Motivação, Discussão e Debate, Ausência de Conflitos, Tempo para Idéias, Ludismo e Humor, Liberdade, Suporte as Idéias, Alegria e Dinamismo, Correr Risco, Confiança e Abertura. Os resultados foram significativos predominando a organização educacional particular em todas as variáveis estudadas, e, em segundo lugar a organização educacional pública. As organizações empresariais, públicas e particulares se assemelharam. Conclui-se que a organização educacional possui mais características que conduz-se a um clima criativo e inovador do que as organizações empresariais (AU)

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