Complete Measurement of the Λ Electromagnetic Form Factors

The exclusive process e^{+}e^{-}→ΛΛ[over ¯], with Λ→pπ^{-} and Λ[over ¯]→p[over ¯]π^{+}, has been studied at sqrt[s]=2.396  GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9  pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst)  pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.

Amplitude Analysis of D_{s}^{+}→π^{+}π^{0}η and First Observation of the W-Annihilation Dominant Decays D_{s}^{+}→a_{0}(980)^{+}π^{0} and D_{s}^{+}→a_{0}(980)^{0}π^{+}

We present the first amplitude analysis of the decay D_{s}^{+}→π^{+}π^{0}η. We use an e^{+}e^{-} collision data sample corresponding to an integrated luminosity of 3.19  fb^{-1} collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. We observe for the first time the W-annihilation dominant decays D_{s}^{+}→a_{0}(980)^{+}π^{0} and D_{s}^{+}→a_{0}(980)^{0}π^{+}. We measure the absolute branching fraction B(D_{s}^{+}→a_{0}(980)^{+(0)}π^{0^{(}+)},a_{0}(980)^{+(0)}→π^{+(0)}η)=(1.46±0.15_{stat}±0.23_{sys})%, which is larger than the branching fractions of other measured pure W-annihilation decays by at least one order of magnitude. In addition, we measure the branching fraction of D_{s}^{+}→π^{+}π^{0}η with significantly improved precision.

Extraction of the ^{235}U and ^{239}Pu Antineutrino Spectra at Daya Bay

This Letter reports the first extraction of individual antineutrino spectra from ^{235}U and ^{239}Pu fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses 3.5×10^{6} inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, ^{235}U and ^{239}Pu, are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4-6 MeV, a 7% (9%) excess of events is observed for the ^{235}U (^{239}Pu) spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is 4.0σ for ^{235}U spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at 5.3σ. In the energy range of 4-6 MeV, a maximal local discrepancy of 6.3σ is observed.

[Association between interleukin-17A and 17F single nucleotide polymorphisms and knee osteoarthritis]

Objective: To investigate the association between single nucleotide polymorphisms (SNP) of IL-17A (rs2275913) and IL-17F (rs763780) genes and susceptibility to knee osteoarthritis (KOA) in Chinese Han and Tibetan populations. Methods: A case-control study was conducted. Total of 122 Han KOA patients and 124 Han healthy controls and 76 Tibetan KOA patients and 68 Tibetan healthy controls in Qinghai Province were selected between 2015 and 2017. SNP typing was performed on four groups of rs2275913 and rs763780 polymorphisms by polymerease chain reaction (PCR)-sequencing to detect IL-17A and IL-17 F genotype frequencies and allele frequencies. The t test was used to compare data between groups. Results: The genotype AA frequency of IL-17A (rs2275913) was significantly different between the Han KOA and the control group (OR=2.625, P=0.016). Compared with the frequency of allele A in healthy control group, the allele A frequency in Han KOA group was significantly higher(OR=1.445, P=0.047); the genotype frequency of IL-17A,however,was comparable between the KOA and the healthy control in Tibetan population (OR=1.696, 1.355, both P>0.05); there were also not difference in the IL-17F (rs763780) genotype frequency and allele frequency between the Han KOA and Tibetan KOA groups and two control groups,respectively (OR=1.346, 1.126, both P>0.05). Conclusion: It is highly likely that the pathogenesis of KOA in Chinese Han population is positively related to the genotype AA and allele A of IL-17A (rs2275913).

Study of e^{+}e^{-}→γωJ/ψ and Observation of X(3872)→ωJ/ψ

We study the e^{+}e^{-}→γωJ/ψ process using 11.6  fb^{-1} e^{+}e^{-} annihilation data taken at center-of-mass energies from sqrt[s]=4.008  GeV to 4.600 GeV with the BESIII detector at the BEPCII storage ring. The X(3872) resonance is observed for the first time in the ωJ/ψ system with a significance of more than 5σ. The relative decay ratio of X(3872)→ωJ/ψ and π^{+}π^{-}J/ψ is measured to be R=1.6_{-0.3}^{+0.4}±0.2, where the first uncertainty is statistical and the second systematic (the same hereafter). The sqrt[s]-dependent cross section of e^{+}e^{-}→γX(3872) is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the Y(4200), with a mass of 4200.6_{-13.3}^{+7.9}±3.0  MeV/c^{2} and a width of 115_{-26}^{+38}±12  MeV. In addition, to describe the ωJ/ψ mass distribution above 3.9  GeV/c^{2}, we need at least one additional Breit-Wigner resonance, labeled as X(3915), in the fit. The mass and width of the X(3915) are determined. The resonant parameters of the X(3915) agree with those of the Y(3940) in B→KωJ/ψ and of the X(3915) in γγ→ωJ/ψ observed by the Belle and BABAR experiments within errors.

Observation of the Decay X(3872)→π^{0}χ_{c1}(1P)

Using a total of 9.0  fb^{-1} of e^{+}e^{-} collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes e^{+}e^{-}→γX(3872) with X(3872)→π^{0}χ_{cJ} for J=0, 1, 2. We report the first observation of X(3872)→π^{0}χ_{c1}, a new decay mode of the X(3872), with a statistical significance of more than 5σ for all systematic fit variations. Normalizing to the previously established process e^{+}e^{-}→γX(3872) with X(3872)→π^{+}π^{-}J/ψ, we find B(X(3872)→π^{0}χ_{c1})/B(X(3872)→π^{+}π^{-}J/ψ)=0.88_{-0.27}^{+0.33}±0.10, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to π^{0}χ_{c0} and π^{0}χ_{c2} of 19 and 1.1, respectively.

Precision Measurement of the Branching Fractions of η^{'} Decays

Based on a sample of (1310.6±7.0)×10^{6}J/ψ events collected with the BESIII detector, we present measurements of J/ψ and η^{'} absolute branching fractions using the process J/ψ→γη^{'}. By analyzing events where the radiative photon converts into an e^{+}e^{-} pair, the branching fraction for J/ψ→γη^{'} is measured to be (5.27±0.03±0.05)×10^{-3}. The absolute branching fractions of the five dominant decay channels of the η^{'} are then measured for the first time and are determined to be B(η^{'}→γπ^{+}π^{-})=(29.90±0.03±0.55)%, B(η^{'}→ηπ^{+}π^{-})=(41.24±0.08±1.24)%, B(η^{'}→ηπ^{0}π^{0})=(21.36±0.10±0.92)%, B(η^{'}→γω)=(2.489±0.018±0.074)%, and B(η^{'}→γγ)=(2.331±0.012±0.035)%, where the first uncertainties are statistical and the second systematic.

Measurement of the Dynamics of the Decays D_{s}^{+}→η^{(')}e^{+}ν_{e}

Using e^{+}e^{-} annihilation data corresponding to an integrated luminosity of 3.19  fb^{-1} collected at a center-of-mass energy of 4.178 GeV with the BESIII detector, we measure the absolute branching fractions B_{D_{s}^{+}→ηe^{+}ν_{e}}=(2.323±0.063_{stat}±0.063_{syst})% and B_{D_{s}^{+}→η^{'}e^{+}ν_{e}}=(0.824±0.073_{stat}±0.027_{syst})% via a tagged analysis technique, where one D_{s} is fully reconstructed in a hadronic mode. Combining these measurements with previous BESIII measurements of B_{D^{+}→η^{(')}e^{+}ν_{e}}, the η-η^{'} mixing angle in the quark flavor basis is determined to be ϕ_{P}=(40.1±2.1_{stat}±0.7_{syst})°. From the first measurements of the dynamics of D_{s}^{+}→η^{(')}e^{+}ν_{e} decays, the products of the hadronic form factors f_{+}^{η^{(')}}(0) and the Cabibbo-Kobayashi-Maskawa matrix element |V_{cs}| are determined with different form factor parametrizations. For the two-parameter series expansion, the results are f_{+}^{η}(0)|V_{cs}|=0.4455±0.0053_{stat}±0.0044_{syst} and f_{+}^{η^{'}}(0)|V_{cs}|=0.477±0.049_{stat}±0.011_{syst}.

Evidence of a Resonant Structure in the e^{+}e^{-}→π^{+}D^{0}D^{*-} Cross Section between 4.05 and 4.60 GeV

The cross section of the process e^{+}e^{-}→π^{+}D^{0}D^{*-} for center-of-mass energies from 4.05 to 4.60 GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40 GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of 4228.6±4.1±6.3  MeV/c^{2} and a width of 77.0±6.8±6.3  MeV, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the Y(4220) state and the theoretical prediction of a DD[over ¯]_{1}(2420) molecule. This result is the first observation of Y(4220) associated with an open-charm final state. Fits with three resonance functions with additional Y(4260), Y(4320), Y(4360), ψ(4415), or a new resonance do not show significant contributions from either of these resonances. The second enhancement is not from a single known resonance. It could contain contributions from ψ(4415) and other resonances, and a detailed amplitude analysis is required to better understand this enhancement.

[Comparison of three different posterior cervical approaches for treating cervical spine trauma with ossification of posterior longitudinal ligament]

Objective: To investigate the clinical application value of using laminoplasty combine with short-segment pedicle screw fixation in the treatment of cervical spine trauma patients with ossification of posterior longitudinal ligament (OPLL). Methods: Fifty-four cervical spine trauma patients with OPLL from June 2014 to June 2016 were retrospectively analyzed of Department of Spine Surgery, Changzheng Hospital, Naval Military Medical University. There were 31 males and 23 females, aging (68.4±4.3) years (rang: 46 to 82 years). All patients had a history of cervical spine trauma, confirmed by imaging examination of OPLL, and there are signs and symptoms related to cervical spinal cord compression. Eighteen patients underwent one-stage laminoplasty combine with short-segment pedicle screw fixation(group A), and 15 patients underwent posterior cervical laminectomy and pedicle screw fixation (group B). Twenty-one patients underwent posterior laminoplasty (C group). According to the range of OPLL and the compression of the spinal cord, the range of laminoplasty was selected. MRI scan was used to evaluated the compression condition of cervical spine and the injury condition of anterior longitudinal ligament injury and other factors that can cause local instability of the cervical spine. Posterior unilateral pedicle screw fixation (two pedicles) were performed in the instability segment. The neurological function of the patients was assessed by the Japanese Orthopedic Association (JOA) Score before surgery, the second day after surgery, 3 months, 1 year and the last follow-up. The cervical spine X-ray films were used to evaluate cervical curvature, cervical spine activity and internal fixation-related complications. Results: The average follow-up time was 18 months (6-30 months). Satisfactory neurological improvement was achieved in all three groups, and no internal fixation-related complications occurred during follow-up. The range of laminoplasty was 22 cases in 4 segments (C(3)-C(6), C(4)-C(7)) and 17 cases in 5 segments (C(3)-C(7)). Unilateral pedicle screw fixation was performed in 11 patients with C(3-4) fixation and 7 patients with C(4-5) fixation. Cervical curvature was basically the same in the three groups after operation and at the last follow-up. No significant changes in cervical curvature and kyphosis were observed during the follow-up period. The overall cervical mobility (C(2)-C(7)) in group A and group C had no significant difference compared with preoperative (P=0.077). The overall mobility of cervical vertebrae in group B was significantly lower than that before surgery (P=0.013). Conclusions: For cervical spine trauma patients with OPLL, laminoplasty combined short-segment pedicle screw fixation can increase cervical segmental stability while extensive decompression of cervical spinal cord compression. At the same time, to some extent, the complications of postoperative axial symptoms caused by posterior cervical laminectomy and pedicle screw fixation were avoided.

Determination of the Pseudoscalar Decay Constant f_{D_{s}^{+}} via D_{s}^{+}→μ^{+}ν_{μ}

Using a 3.19  fb^{-1} data sample collected at an e^{+}e^{-} center-of-mass energy of E_{cm}=4.178  GeV with the BESIII detector, we measure the branching fraction of the leptonic decay D_{s}^{+}→μ^{+}ν_{μ} to be B_{D_{s}^{+}→μ^{+}ν_{μ}}=(5.49±0.16_{stat}±0.15_{syst})×10^{-3}. Combining our branching fraction with the masses of the D_{s}^{+} and μ^{+} and the lifetime of the D_{s}^{+}, we determine f_{D_{s}^{+}}|V_{cs}|=246.2±3.6_{stat}±3.5_{syst}  MeV. Using the c→s quark mixing matrix element |V_{cs}| determined from a global standard model fit, we evaluate the D_{s}^{+} decay constant f_{D_{s}^{+}}=252.9±3.7_{stat}±3.6_{syst}  MeV. Alternatively, using the value of f_{D_{s}^{+}} calculated by lattice quantum chromodynamics, we find |V_{cs}|=0.985±0.014_{stat}±0.014_{syst}. These values of B_{D_{s}^{+}→μ^{+}ν_{μ}}, f_{D_{s}^{+}}|V_{cs}|, f_{D_{s}^{+}} and |V_{cs}| are each the most precise results to date.

First Measurement of the Form Factors in D_{s}^{+}→K^{0}e^{+}ν_{e} and D_{s}^{+}→K^{*0}e^{+}ν_{e} Decays

We report on new measurements of Cabibbo-suppressed semileptonic D_{s}^{+} decays using 3.19  fb^{-1} of e^{+}e^{-} annihilation data sample collected at a center-of-mass energy of 4.178 GeV with the BESIII detector at the BEPCII collider. Our results include branching fractions B(D_{s}^{+}→K^{0}e^{+}ν_{e})=[3.25±0.38(stat)±0.16(syst)]×10^{-3} and B(D_{s}^{+}→K^{*0}e^{+}ν_{e})=[2.37±0.26(stat)±0.20(syst)]×10^{-3}, which are much improved relative to previous measurements, and the first measurements of the hadronic form-factor parameters for these decays. For D_{s}^{+}→K^{0}e^{+}ν_{e}, we obtain f_{+}(0)=0.720±0.084(stat)±0.013(syst), and for D_{s}^{+}→K^{*0}e^{+}ν_{e}, we find form-factor ratios r_{V}=V(0)/A_{1}(0)=1.67±0.34(stat)±0.16(syst) and r_{2}=A_{2}(0)/A_{1}(0)=0.77±0.28(stat)±0.07(syst).

Observation of D^{+}→f_{0}(500)e^{+}ν_{e} and Improved Measurements of D→ρe^{+}ν_{e}

Using a data sample corresponding to an integrated luminosity of 2.93  fb^{-1} recorded by the BESIII detector at a center-of-mass energy of 3.773 GeV, we present an analysis of the decays D^{0}→π^{-}π^{0}e^{+}ν_{e} and D^{+}→π^{-}π^{+}e^{+}ν_{e}. By performing a partial wave analysis, the π^{+}π^{-} S-wave contribution to D^{+}→π^{-}π^{+}e^{+}ν_{e} is observed to be (25.7±1.6±1.1)% with a statistical significance greater than 10σ, besides the dominant P-wave contribution. This is the first observation of the S-wave contribution. We measure the branching fractions B(D^{0}→ρ^{-}e^{+}ν_{e})=(1.445±0.058±0.039)×10^{-3}, B(D^{+}→ρ^{0}e^{+}ν_{e})=(1.860±0.070±0.061)×10^{-3}, and B(D^{+}→f_{0}(500)e^{+}ν_{e},f_{0}(500)→π^{+}π^{-})=(6.30±0.43±0.32)×10^{-4}. An upper limit of B(D^{+}→f_{0}(980)e^{+}ν_{e},f_{0}(980)→π^{+}π^{-})<2.8×10^{-5} is set at the 90% confidence level. We also obtain the hadronic form factor ratios of D→ρe^{+}ν_{e} at q^{2}=0 assuming the single-pole dominance parametrization: r_{V}={[V(0)]/[A_{1}(0)]}=1.695±0.083±0.051, r_{2}={[A_{2}(0)]/[A_{1}(0)]}=0.845±0.056±0.039.

Study of the D^{0}→K^{-}μ^{+}ν_{μ} Dynamics and Test of Lepton Flavor Universality with D^{0}→K^{-}ℓ^{+}ν_{ℓ} Decays

Using e^{+}e^{-} annihilation data of 2.93  fb^{-1} collected at center-of-mass energy sqrt[s]=3.773  GeV with the BESIII detector, we measure the absolute branching fraction of D^{0}→K^{-}μ^{+}ν_{μ} with significantly improved precision: B_{D^{0}→K^{-}μ^{+}ν_{μ}}=(3.413±0.019_{stat}±0.035_{syst})%. Combining with our previous measurement of B_{D^{0}→K^{-}e^{+}ν_{e}}, the ratio of the two branching fractions is determined to be B_{D^{0}→K^{-}μ^{+}ν_{μ}}/B_{D^{0}→K^{-}e^{+}ν_{e}}=0.974±0.007_{stat}±0.012_{syst}, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. A study of the ratio of the two branching fractions in different four-momentum transfer regions is also performed, and no evidence for lepton flavor universality violation is found with current statistics. Taking inputs from global fit in the standard model and lattice quantum chromodynamics separately, we determine f_{+}^{K}(0)=0.7327±0.0039_{stat}±0.0030_{syst} and |V_{cs}|=0.955±0.005_{stat}±0.004_{syst}±0.024_{LQCD}.

Quantitation of Total and Free Thiol β2-Glycoprotein I Levels for Diagnostic and Prognostic Purposes in the Antiphospholipid Syndrome

β₂-Glycoprotein I is the major autoantigen in the antiphospholipid syndrome (APS), a prothrombotic disorder characterized by the occurrence of either venous or arterial thrombosis. In women it is also associated with an increased risk of obstetric complications such as recurrent miscarriages. We have identified that the plasma protein β₂-glycoprotein I in healthy individuals exists in an optimal ratio between two distinct forms, an oxidized and free thiol, reduced form. This ratio is disrupted in pathophysiological conditions associated with increased oxidative stress such as the APS, but also in the setting of age-related macular degeneration and gram-negative sepsis. We have developed assays that quantify plasma/serum levels of total and free thiol β₂-glycoprotein I which can potentially be used for risk stratification and prognostic purposes in the early stages of the aforementioned conditions.

Cyber security detection and monitoring at IHEP private cloud for web services

To improve hardware utilization and save manpower in system maintenance, most of the web services in IHEP have been migrated to a private cloud build upon OpenStack. However, cyber security attacks becomes a serious threats to the cloud progressively. Therefore, a cyber security detection and monitoring system is deployed for this cloud platform. This system collects various security related logs as data sources, and processes them in a framework composed of open source data store, analysis and visualization tools. With this system, security incidents and events can be handled in time and rapid response can be taken to protect cloud platform against cyber security threats.

Measurement of the Absolute Branching Fraction of the Inclusive Semileptonic Λ_{c}^{+} Decay

Using a data sample of e^{+}e^{-} collisions corresponding to an integrated luminosity of 567  pb^{-1} collected at a center-of-mass energy of sqrt[s]=4.6  GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic Λ_{c}^{+} decay with a double-tag method. We obtain B(Λ_{c}^{+}→Xe^{+}ν_{e})=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λ_{c}^{+} lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D^{0} and D^{+}), we obtain the ratio of the inclusive semileptonic decay widths Γ(Λ_{c}^{+}→Xe^{+}ν_{e})/Γ[over ¯](D→Xe^{+}ν_{e})=1.26±0.12.

Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor ν[over ¯]_{e} inverse β decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the inverted hierarchy.

[Differences in anterior segment structure between Chinese Han people and American Caucasians]

Objective: To compare the difference of anterior segment structure between Chinese Han people and American Caucasians, and to explore the confounding factors of anterior chamber angle. Methods: Cross-sectional study. The study was designed to include two healthy groups of Chinese Han people (enrolled from Department of Ophthalmology, Peking University Third Hospital) and American Caucasians (enrolled from Department of Ophthalmology, University of California, San Francisco) from May 2008 to December 2010, each with approximately 120 participants, including 15 persons of each gender in each decade between 40 and 80 years of age. The parameters of the anterior segment were measured by the automatic refractive test, A-ultrasound and ultrasound biomicroscopy. Differences between the two groups were compared with the independent-sample t test or Wilcoxon two-sample test for continuous variable data and the χ(2) test for classified variable data. Multiple linear regression models were performed to analyze the associated factors of anterior chamber angle. Results: There were 118 subjects (118 eyes) and 117 subjects (117 eyes) enrolled in the Chinese and American Caucasians groups, respectively. Compared to Caucasians, Chinese had smaller A-ultrasound measured anterior chamber depth [(3.03±0.34) mm vs. (3.38±0.36) mm, t=-5.791, P<0.001], smaller relative lens position [0.227 (0.198, 0.256) vs. 0.235 (0.191, 0.262), Z=-3.063, P=0.002], smaller axial length [23.3 (20.9,28.3) mm vs. 24.2 (20.8,28.5) mm, Z=-5.510, P<0.001], smaller iris root distance [0.111 (0.000, 0.401) mm vs. 0.142 (0.000, 0.451) mm, Z=-3.188, P=0.001], smaller ciliary body thickness at 1 mm posterior to the scleral spur [0.661 (0.424, 0.892) mm vs. 0.716 (0.467, 0.942) mm, Z=-3.456, P=0.001], smaller trabecular ciliary process distance [0.780 (0.410, 1.400) mm vs. 0.930 (0.420, 1.470) mm, Z=-3.191, P=0.001], smaller trabecular ciliary process angle [73.4° (36.3°, 115.3°) vs. 81.1° (47.9°, 147.9°), Z=-3.407, P=0.001], smaller angle opening distance at 500 μm (AOD500) [0.181 (0.000, 0.703) mm vs. 0.264 (0.000, 0.806) mm, Z=-3.444, P=0.001], smaller angle recess area (ARA) [0.118 (0.011, 0.457) mm(2) vs. 0.179 (0.000, 0.626) mm(2), Z=-3.814, P<0.001], larger spherical equivalent [0.40 (-5.80, 4.00) D vs. -0.70 (-8.00, 4.00) D, Z=-5.454, P<0.001], larger lens thickness [(4.62±0.40) mm vs. (4.52±0.40) mm, t=2.077, P=0.039] and larger iris thickness [0.430 (0.280, 0.600) mm vs. 0.410 (0.240, 0.580) mm, Z=-2.263, P=0.024]. On average, with each decade of the increased age, Chinese had a greater decrease in the AOD500 than Caucasians (0.040 mm in Chinese vs. 0.030 mm in Caucasians), while the angle recess area decreased at the same rate (0.020 mm(2) in both groups). After adjusted for age, gender, spherical equivalent, axial length and other parameters of the anterior segment, the trabecular ciliary process angle [for AOD500, standardized regression coefficient (SRC)=0.487, R(2)=0.549, P<0.001; for ARA, SRC=0.372, R(2)=0.502, P<0.001] and anterior chamber depth (for AOD500, SRC=0.413, R(2)=0.476, P<0.001; for ARA, SRC=0.331, R(2)=0.403, P<0.001) were the main factors of anterior chamber angle parameters for Chinese and Caucasians, respectively. Conclusions: Compared with age and gender matched American Caucasians, Chinese Han people have more crowded anterior chambers and narrower anterior chamber angles. The more anteriorly positioned ciliary processes and shallower anterior chambers are the main factors that contributed to more crowded anterior chambers in Chinese Han people and American Caucasians, respectively. (Chin J Ophthalmol, 2018, 54: 820-826).

Measurement of the Branching Fraction For the Semileptonic Decay D^{0(+)}→π^{-(0)}μ^{+}ν_{μ} and Test of Lepton Flavor Universality

Using a data sample corresponding to an integrated luminosity of 2.93  fb^{-1} taken at a center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we perform an analysis of the semileptonic decays D^{0(+)}→π^{-(0)}μ^{+}ν_{μ}. The branching fractions of D^{0}→π^{-}μ^{+}ν_{μ} and D^{+}→π^{0}μ^{+}ν_{μ} are measured to be (0.272±0.008_{stat}±0.006_{syst})% and (0.350±0.011_{stat}±0.010_{syst})%, respectively, where the former is of much improved precision compared to previous results and the latter is determined for the first time. Using these results along with previous BESIII measurements of D^{0(+)}→π^{-(0)}e^{+}ν_{e}, we calculate the branching fraction ratios to be R^{0}≡B_{D^{0}→π^{-}μ^{+}ν_{μ}}/B_{D^{0}→π^{-}e^{+}ν_{e}}=0.922±0.030_{stat}±0.022_{syst} and R^{+}≡B_{D^{+}→π^{0}μ^{+}ν_{μ}}/B_{D^{+}→π^{0}e^{+}ν_{e}}=0.964±0.037_{stat}±0.026_{syst}, which are compatible with the theoretical expectation of lepton flavor universality within 1.7σ and 0.5σ, respectively. We also examine the branching fraction ratios in different four-momentum transfer square regions, and find no significant deviations from the standard model predictions.