RESUMO
All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction to a_{µ}^{HVP} for the first time with physical values of m_{u} and m_{d} and dynamical u, d, s, and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δa_{µ}^{HVP,m_{u}≠m_{d}}=+1.5(7)%, in agreement with estimates from phenomenology.
RESUMO
The rare decay Bâπâ^{+}â^{-} arises from bâd flavor-changing neutral currents and could be sensitive to physics beyond the standard model. Here, we present the first ab initio QCD calculation of the Bâπ tensor form factor f_{T}. Together with the vector and scalar form factors f_{+} and f_{0} from our companion work [J. A. Bailey et al., Phys. Rev. D 92, 014024 (2015)], these parametrize the hadronic contribution to Bâπ semileptonic decays in any extension of the standard model. We obtain the total branching ratio BR(B^{+}âπ^{+}µ^{+}µ^{-})=20.4(2.1)×10^{-9} in the standard model, which is the most precise theoretical determination to date, and agrees with the recent measurement from the LHCb experiment [R. Aaij et al., J. High Energy Phys. 12 (2012) 125].
Assuntos
Partículas Elementares , Modelos Teóricos , Física Nuclear , PrótonsRESUMO
We calculate the kaon semileptonic form factor f+(0) from lattice QCD, working, for the first time, at the physical light-quark masses. We use gauge configurations generated by the MILC Collaboration with Nf = 2 + 1 + 1 flavors of sea quarks, which incorporate the effects of dynamical charm quarks as well as those of up, down, and strange. We employ data at three lattice spacings to extrapolate to the continuum limit. Our result, f+(0) = 0.9704(32), where the error is the total statistical plus systematic uncertainty added in quadrature, is the most precise determination to date. Combining our result with the latest experimental measurements of K semileptonic decays, one obtains the Cabibbo-Kobayashi-Maskawa matrix element |V(us)| = 0.22290(74)(52), where the first error is from f+(0) and the second one is from experiment. In the first-row test of Cabibbo-Kobayashi-Maskawa unitarity, the error stemming from |V(us)| is now comparable to that from |V(ud)|.
RESUMO
The semileptonic decay channel BâDτν is sensitive to the presence of a scalar current, such as that mediated by a charged-Higgs boson. Recently, the BABAR experiment reported the first observation of the exclusive semileptonic decay BâDτ(-)ν, finding an approximately 2σ disagreement with the standard-model prediction for the ratio R(D)=BR(BâDτν)/BR(BâDâν), where â = e,µ. We compute this ratio of branching fractions using hadronic form factors computed in unquenched lattice QCD and obtain R(D)=0.316(12)(7), where the errors are statistical and total systematic, respectively. This result is the first standard-model calculation of R(D) from ab initio full QCD. Its error is smaller than that of previous estimates, primarily due to the reduced uncertainty in the scalar form factor f(0)(q(2)). Our determination of R(D) is approximately 1σ higher than previous estimates and, thus, reduces the tension with experiment. We also compute R(D) in models with electrically charged scalar exchange, such as the type-II two-Higgs-doublet model. Once again, our result is consistent with, but approximately 1σ higher than, previous estimates for phenomenologically relevant values of the scalar coupling in the type-II model. As a by-product of our calculation, we also present the standard-model prediction for the longitudinal-polarization ratio P(L)(D)=0.325(4)(3).
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Cycloplegics, corticosteroids, and nonsteroidal anti-inflammatory drugs have been applied in the treatment of postoperative inflammation following cataract extraction. Of these, topical preparations of nonsteroidal anti-inflammatory drugs, such as ketorolac tromethamine 0.5% and diclofenac sodium 0.1%, offer comparable efficacy to corticosteroids in the reduction of postoperative inflammation, and offer lower risks of adverse events in most patients. Comparative studies of these drugs from the past 5 years are highlighted.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Extração de Catarata/efeitos adversos , Uveíte Anterior/tratamento farmacológico , Humanos , Inflamação/tratamento farmacológico , Inflamação/etiologia , Esteroides , Uveíte Anterior/etiologiaRESUMO
PURPOSE: To compare the anti-inflammatory and analgesic efficacy and safety of ketorolac tromethamine 0.5% ophthalmic solution with those of prednisolone acetate 1% in patients having cataract surgery. SETTING: Shawnee Mission Eye Care, Shawnee Mission, Kansas, USA. METHODS: This double-blind, randomized, single-site study comprised 59 healthy men and women with a clinical diagnosis of routine ocular cataract requiring surgical removal. All patients had extracapsular cataract extraction and posterior chamber intraocular lens implantation. After surgery, patients were randomized to receive ketorolac tromethamine 0.5% or prednisolone acetate 1%, self-instilled in the treated eye, according to the following schedule: 1 to 2 drops 4 times daily (week 1); 3 times daily (week 2); 2 times daily (week 3); once daily (week 4). Patients were examined postoperatively on days 1, 7, and 28. Intraocular anti-inflammatory efficacy was assessed by lid edema, lid injection, conjunctival injection, corneal edema, ciliary flush, and anterior chamber cells. Analgesic efficacy was assessed by patient self-rated pain severity, pain frequency, total symptom sum, and overall global improvement. RESULTS: Both treatments produced comparable reductions in intraocular inflammation and pain after cataract surgery and were well tolerated by patients. No adverse events were reported, and there were no significant changes in intraocular pressure in either group. Improvements in visual acuity were also similar in both groups. CONCLUSION: Ketorolac tromethamine 0.5% ophthalmic solution was as effective and well-tolerated as prednisolone acetate 1% solution in controlling postoperative inflammation and pain after cataract surgery.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Extração de Catarata , Complicações Pós-Operatórias/prevenção & controle , Prednisolona/análogos & derivados , Tolmetino/análogos & derivados , Trometamina/análogos & derivados , Adulto , Idoso , Idoso de 80 Anos ou mais , Anti-Inflamatórios/administração & dosagem , Anti-Inflamatórios não Esteroides/administração & dosagem , Método Duplo-Cego , Feminino , Seguimentos , Humanos , Cetorolaco de Trometamina , Implante de Lente Intraocular , Masculino , Pessoa de Meia-Idade , Soluções Oftálmicas/administração & dosagem , Soluções Oftálmicas/uso terapêutico , Medição da Dor , Prednisolona/administração & dosagem , Prednisolona/uso terapêutico , Estudos Retrospectivos , Segurança , Tolmetino/administração & dosagem , Tolmetino/uso terapêutico , Resultado do Tratamento , Trometamina/administração & dosagem , Trometamina/uso terapêutico , Uveíte Anterior/prevenção & controle , Acuidade VisualRESUMO
Large increases in the intraocular pressure (IOP) of postoperative gas-containing eyes may require the removal of gas or fluid to reduce the IOP to the normal range. Application of the ideal gas law to Friedenwald's equation provides a mathematical model of the relationship between IOP, intraocular gas and fluid volumes, and the coefficient of scleral rigidity. This mathematic model shows that removal of a given volume of gas or fluid produces an identical decrease in IOP and that the more gas an eye contains, the greater the volume reduction necessary to reduce the pressure. Application of the model shows that the effective coefficient of scleral rigidity is low (mean K, 0.0021) in eyes with elevated IOP that have undergone vitrectomy and retinal cryopexy and very low (mean K, 0.0013) in eyes with elevated IOP that have undergone placement of a scleral buckle and band. By using the appropriate mean coefficient of rigidity, the volume of material to be aspirated to produce a given decrease in IOP can be predicted with clinically useful accuracy.
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Líquidos Corporais/fisiologia , Gases , Pressão Intraocular/fisiologia , Pressão Atmosférica , Humanos , Matemática , Modelos Biológicos , Esclera/fisiologia , Recurvamento da Esclera , Transtornos da Visão/fisiopatologiaRESUMO
Quantitative, morphometric analysis of 3-dimensional cell shape may prove to be a valuable adjunct to scanning electron microscopy and to the evaluation of epithelial transport phenomena. Therefore, to facilitate the wider use of cell shape analysis, a computer-assisted technique has been developed to supplement or replace the usually tedious and otherwise limited manual techniques previously available. The computer programs described here have been designed to run in a small laboratory computer, do not require a large amount of operator time, and are shown to provide an accuracy and efficiency not practical with manual procedures.
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Células/citologia , Computadores , Animais , Técnicas Citológicas , Matemática , CoelhosRESUMO
With the use of tritiated water, total body water was measured by isotope dilution in 17 normal dogs. Analysis of the plasma arterial disappearance curve up to 20 minutes by a computer program using a weighted least-squares technique makes it possible to predict the final volume of dilution, with acceptable precision from the early curve.