Search

Hong-Da Zhang,&ast; Lei Ding,&ast; Li-Jie Mi, Ai-Kai Zhang, Yuan-Dong Liu, Xiang-Nan Li, Xin-Xin Yan, Yu-Jing Shen, Min Tang State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100037, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Min Tang; Yu-Jing Shen, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences & Peking Union Medical College, 167 Beilishi Road, Xicheng District, Beijing, 100037, People’s Republic of China, Email doctortangmin@yeah.net; shenyj0328@126.comBackground: Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in critically ill patients and significantly impacts mortality. This study sought to evaluate the impact of new-onset AF on mortality in a critically ill population.Methods: This study identified 48018 adult patients admitted to the ICU from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients were categorized as no AF, pre-existing AF, or new-onset AF. We analyzed mortality at 3 months, 6 months, and 1 year.Results: Overall, 31,562 (65.73%) patients had no AF, 4877 (10.16%) had pre-existing AF, and 11,579 (24.11%) had new-onset AF. Median ages were 61.47 years (no AF), 76.12 years (pre-existing AF), and 75.26 years (new-onset AF). New-onset AF was associated with the highest mortality rates: 25.16% at 3 months, 29.23% at 6 months, and 34.04% at 1 year, compared to 17.94%, 22.55%, and 28.52% for pre-existing AF, and 14.54%, 17.25%, and 20.69% for no AF respectively (p < 0.001 for all). Multivariate Cox regression indicated that new-onset AF significantly increased the risk of 1-year mortality by 15.5% compared to no AF (HR: 1.155, 95% CI: 1.101– 1.212; p < 0.001) and by 23.9% compared to pre-existing AF (HR: 1.239, 95% CI: 1.164– 1.318; p < 0.001). Kaplan-Meier analysis confirmed lower survival probabilities for new-onset AF over one year compared to the other groups (p < 0.001).Conclusion: In patients with critical illness, new-onset AF is associated with an increased risk of mortality compared with pre-existing AF or no AF.Keywords: atrial fibrillation, mortality, intensive care unit

Congenital diarrheal disorders (CDD) are a group of rare inherited intestinal disorders, among which CDD7 was recently identified to be associated with only 24 mutations in gene coding for diacylglycerol-acyltransferase 1 (DGAT1).

Jian-Jun Wu,1 Ping-An Zhang,1 Ming-Zhe Chen,2 Yi Zhang,1 Wei-Sha Du,1 Xiao-Ning Li,1 Guo-Chao Ji,1 Liang-Duo Jiang,3 Yang Jiao,4,&ast; Xin Li5,&ast; 1Respiratory Department, The Third Affiliated Hospital, Beijing University of Chinese Medicine, Beijing, People’s Republic of China; 2Infectious Disease Department, Henan Provincial Hospital of Traditional Chinese Medicine, Zhengzhou, Henan, People’s Republic of China; 3Respiratory Department, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, People’s Republic of China; 4Respiratory Department, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, People’s Republic of China; 5Glaucoma Department, Eye Hospital, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xin Li, Glaucoma Department, Eye Hospital, China academy of Chinese Medical Sciences, Beijing, People’s Republic of China, Email doudou8295@163.comBackground: Some patients with chronic obstructive pulmonary disease (COPD) benefit from glucocorticoid (GC) treatment, but its mechanism is unclear.Objective: With the help of the Gene Expression Omnibus (GEO) database, the key genes and miRNA-mRNA related to the treatment of COPD by GCs were discussed, and the potential mechanism was explained.Methods: The miRNA microarray dataset (GSE76774) and mRNA microarray dataset (GSE36221) were downloaded, and differential expression analysis were performed. Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the differentially expressed genes (DEGs). The protein interaction network of the DEGs in the regulatory network was constructed with the STRING database, and the key genes were screened through Cytoscape. Potential downstream target genes regulated by differentially expressed miRNAs (DEMs) were predicted by the miRWalk3.0 database, and miRNA-mRNA regulatory networks were constructed. Finally, some research results were validated.Results: ① Four DEMs and 83 DEGs were screened; ② GO and KEGG enrichment analysis mainly focused on the PI3K/Akt signalling pathway, ECM receptor interaction, etc.; ③ CD2, SLAMF7, etc. may be the key targets of GC in the treatment of COPD; ④ 18 intersection genes were predicted by the mirwalk 3.0 database, and 9 pairs of miRNA-mRNA regulatory networks were identified; ⑤ The expression of miR-320d-2 and TFCP2L1 were upregulated by dexamethasone in the COPD cell model, while the expression of miR-181a-2-3p and SLAMF7 were downregulated.Conclusion: In COPD, GC may mediate the expression of the PI3K/Akt signalling pathway through miR-181a-2-3p, miR-320d-2, miR-650, and miR-155-5p, targeting its downstream signal factors. The research results provide new ideas for RNA therapy strategies of COPD, and also lay a foundation for further research.Keywords: COPD, GC, GEO database, miRNA-mRNA, DEMs, DEGs

Wei-Guo Zhang,1,* Jia-Ping Liu,2,* Xiu-Qin Jia,1 Ji-Yang Zhang,1 Xiang-Nan Li,1 Qi Yang1 1Department of Radiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, 100020, People’s Republic of China; 2Department of Radiology, Beijing Xiongke Hospital, Capital Medical University, Beijing, 100049, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qi YangDepartment of Radiology, Beijing Chaoyang Hospital, Capital Medical University, No. 8 Gongti South Road, Chaoyang District, Beijing, 100020, People’s Republic of ChinaTel/Fax +86-85231928Email qiyang856@163.comObjective: This study aimed to investigate the effects of the Sn100 kVp tube voltage mode on the image quality and radiation dose of computed tomography pulmonary angiography (CTPA).Methods: A total of 145 patients who underwent CTPA were randomly divided into five groups: control group (120 kVp, 150 mAs), test group A (Sn100 kVp, 270 mAs), test group B (120 kVp, 30 mAs), test group C (70 kVp, 150 mAs), and test group D (80 kVp, 70 mAs). After image post-processing, the image quality and radiation dose of each group were analyzed.Results: The computed tomography values of images in the four test groups were more than 250 HU, which met the criteria for diagnosis. The signal-to-noise ratio and contrast-to-noise ratio of the images in the four test groups were lower than those in the control group. The radiation dose in each test group was lower than in the control group. The radiation dose was lowest in test group A.Conclusion: The Sn100 kVp energy spectrum purification protocol can meet the requirements for clinical diagnosis, ensure image quality, and reduce the dose of radiation that patients receive.Keywords: Sn100 kVp, CTPA, radiation dose, pulmonary embolism, dual-source CT

Ling Peng,1,2 Li Han,2 Xiao-Ning Li,2 Ya-Fang Miao,2 Fei Xue,2 Chao Zhou1,3 1School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou, People’s Republic of China; 2Department of Respiratory Medicine, Zhoupu Hospital Affiliated to Shanghai University of Medicine and Health Sciences, Shanghai, People’s Republic of China; 3Department of Respiratory Medicine, Guangming Traditional Chinese Medicine Hospital of Pudong New Area, Shanghai, People’s Republic of ChinaCorrespondence: Chao ZhouDepartment of Respiratory Medicine, Guangming Traditional Chinese Medicine Hospital of Pudong New Area, No. 339 DongMen Street. Pudong New District, Shanghai 201399, People’s Republic of ChinaTel +86-21-68019069Email zhou2000sh@163.comBackground: The differential diagnosis of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with acute pulmonary embolism (APE) complications are difficult because of the variability of clinical presentations and the shortage of an unfailing screening biomarkers or instruments.Objective: Aimed to detect and compare the expression of serum microRNAs (miR-1233, miR-134) in AECOPD patients complicated with APE.Patients/Methods: Blood samples were collected from 52 AECOPD patients (13 patients with APE complications, 39 patients without APE) and 10 patients with stable COPD. Serum miRNAs expression was detected with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The levels of plasma D-dimers were determined by detection with an enzyme-linked immunosorbent assay (ELISA). The receiver-operator characteristic (ROC) curve was used for evaluating the diagnostic accuracy of the studied miRNAs.Results: According to the Wells score, 42 of the 52 AECOPD patients were unlikely to have APE (≤ 4 points), whereas the remaining 10 (> 4 points) were likely to have APE. There were 4 cases (4/13 30.8%) in the AECOPD combined with APE group with a Wells score of > 4 points. The expression levels of miR-1233 and miR-134 in the serum were considerably upregulated in the AECOPD+APE group compared with the AECOPD group and the stable COPD group (P< 0.05). The areas under the curve (AUCs) for miR-134 and miR-1233 were, respectively, 0.931 (95% CI 0.863– 0.999) (P< 0.05) and 0.884 (95% CI 0.79– 0.978) (P< 0.05) and were higher compared with the AUC for D-dimer of 0.628 (95% CI 0.447– 0.809), the AUC for age-adjusted D-dimer of 0.705 (95% CI 0.525– 0.885) and the AUC for Wells score of 0.577 (95% CI 0.389– 0.765).Conclusion: Our study indicated that serum miR-1233 and miR-134 have high clinical value in the early diagnosis of AECOPD patients combined with APE, or could be used as potential biomarkers for clinical identification of AECOPD with or without APE complication.Keywords: acute exacerbation of chronic obstructive pulmonary disease, acute pulmonary embolism, D-dimer, microRNA, biomarker

Meng-Jie Yang, Hong-Rong Xu, Hui Li, Wei-Li Chen, Fei Yuan, Xue-Ning Li Department of Clinical Pharmacology, Zhongshan Hospital, Fudan University, Shanghai, People’s Republic of ChinaCorrespondence: Xue-Ning LiDepartment of Clinical Pharmacology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, People’s Republic of ChinaTel +86 21 31587861Fax +86 21 64437963Email li.xuening@zs-hospital.sh.cnPurpose: Aprepitant is used to prevent nausea and vomiting associated with moderately and highly emetogenic chemotherapy. In this open-label, 2-period study, the safety, tolerability, and pharmacokinetics (PK) of aprepitant (EMEND®) were evaluated in healthy Chinese and Caucasian subjects.Patients and Methods: Twelve Chinese and 12 Caucasian subjects were to receive a 125 mg single-dose of aprepitant during period 1; subsequently, after 15 days washout, only Chinese subjects were to receive the 3-day regimen in period 2. In each period, serial blood samples were collected and analyzed by a validated liquid chromatographic and mass spectrometric method to characterize aprepitant PK across both groups.Results: In both Chinese and Caucasian subjects, there were no serious adverse events. AUC0-∞, Cmax, Tmax, and t1/2 were largely comparable between the two ethnicities. Comparing the result of period 1 in Chinese and Caucasian subjects, the geometric least-squares mean maximum plasma concentrations (Cmax) were 1482 ng/mL and 1435 ng/mL, and the area under the concentration–time curve (AUC0-∞) 34,035 hr·ng/mL and 34,188 hr·ng/mL. In period 2, the geometric mean AUC0– 24 on Day 1 and Day 3 were 19,446 hr·ng/mL and 27,843 hr·ng/mL, and the geometric mean Cmax on Day 1 and Day 3 were 1423 ng/mL and 1757 ng/mL, respectively.Conclusion: Aprepitant is generally safe and well tolerated in healthy Chinese and Caucasian subjects. Aprepitant PK is comparable between Chinese and Caucasian subjects following single-dose administration. The PK following a clinical 3-day regimen on healthy Chinese subjects has been characterized.Keywords: pharmacokinetics, aprepitant, chemotherapy-induced nausea and vomiting, ethnicity, healthy subjects

Chao Liu,1 Hong Lu,2 Fei Yuan,1 Wei-Li Chen,1 Hong-Rong Xu,1 Hui Li,1 Cheng-Pang Hsu,3 Ogo Egbuna,3 Jihua Wu,2 Clapton Dias,3 Bassam Abosaleem,3 Jitesh Rana,3 Maria Laura Monsalvo,3 Xue-Ning Li,1 Zhigang Yu4 1Department of Clinical Pharmacology, Zhongshan Hospital, Fudan University, Shanghai, People’s Republic of China; 2Clinical Pharmacology and Early Development, Amgen China R & D Center, Shanghai, People’s Republic of China; 3Research & Development, Amgen Inc., Thousand Oaks, CA, USA; 4Clinical Development, Amgen China R & D Center, Shanghai, People’s Republic of ChinaCorrespondence: Xue-Ning LiDepartment of Clinical Pharmacology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, People’s Republic of ChinaTel +86 21 6026 7666Email li.xuening@zs-hospital.sh.cnZhigang YuResearch & Development, Amgen Inc., Thousand Oaks, CA 91320, USATel +1 805 447-9384Email zhigangy@amgen.comPurpose: Evolocumab is a human monoclonal antibody that reduces circulating low-density lipoprotein cholesterol (LDL-C) by inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9). Data on evolocumab pharmacokinetics and pharmacodynamics are derived mostly from Caucasian populations. The objectives of this study were to characterize the single-dose pharmacokinetic and pharmacodynamic parameters, safety, and tolerability of evolocumab in healthy Chinese subjects.Subjects and methods: This was a phase 1, randomized, double-blind, placebo-controlled study (CTR20150465). Two parallel cohorts were randomized 5:1 to receive single subcutaneous injections of either evolocumab (140 mg or 420 mg) or placebo. Pharmacokinetics, pharmacodynamics, and safety were evaluated through day 85. The primary endpoints were maximum concentration (Cmax) and area under the drug concentration–time curve from time 0 to time of last quantifiable concentration (AUClast).Results: Thirty-six men (median age 26) were enrolled to receive evolocumab 140 mg (n=15), evolocumab 420 mg (n=15), or placebo (n=6). After 140 mg and 420 mg evolocumab, mean (SD) Cmax was 13.8 (3.6 μg/mL and 67.6 (15.2) μg/mL, respectively, and mean (SD) AUClast was 166 (55) day·μg/mL and 1110 (274) day·μg/mL, respectively. LDL-C declined reversibly, with reductions of 70% at 140 mg and 71% at 420 mg. Maximum effects on LDL-C and PCSK9 levels were reached by day 15 and 24 hrs, respectively, at 140 mg, and by day 22 and 4 hrs, respectively, at 420 mg. No serious adverse events occurred and the overall incidence of treatment-emergent adverse events was similar for evolocumab and placebo: 26.7% (140 mg) and 33.3% (placebo); 66.7% (420 mg) and 66.7% (placebo).Conclusion: In this population of healthy Chinese subjects, single 140 mg and 420 mg doses of evolocumab exhibited nonlinear kinetics and more than dose-proportional increases in exposure, were associated with up to 71% reduction in LDL-C, and demonstrated a safety profile similar to placebo.Keywords: cardiovascular disease, homozygous familial hypercholesterolemia, PCSK9 inhibitors, monoclonal antibodies, ethnic sensitivity

Jing-Ping Liu,1 Ye-Zhi Xiao,1 Yu Hu,1 Xiao-Nian Li,2 Ming-Jiang Wu,3 Yong Zhao,1 Yan Zhao,1 Ze-Jin Ma,1 Jing Shen11Department of Chemistry, Yunnan Normal University, Kunming 650092, People’s Republic of China; 2State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Kunming 650201, People’s Republic of China; 3Criminal Science and Technology Key Lab of Yunnan Police College, Kunming 650223, People’s Republic of ChinaCorrespondence: Jing-Ping Liu; Jing ShenDepartment of Chemistry, Yunnan Normal University, No. 298, 121st Street, Yunnan, Kunming 650092, People’s Republic of ChinaTel/Fax +86 8 716 513 2144Email Liujp72@163.com shenjingbox0225@hotmail.comBackground: Neolaxiflorin B is derived from ent-kaurane like laxiflorin J and eriocalyxin B with a relatively low potency as an antitumor agent. During preliminary structure–activity relationship studies, the α,β-unsaturated ketone (enone) system is an important active group.Methods: Seven neolaxiflorin B derivatives containing α,β-unsaturated ketone moieties were synthesized. In vitro, activity was evaluated against three human tumor cell lines and a rat myogenic cell line (HepG2, NSCLC-H292, SNU-1040, and L6, respectively) by MTT assay.Results: Compound 15 appeared a promising antitumor lead due to its cytotoxic potency and relatively high selectivity, with an SI value of 13.14. Flow cytometry analysis was conducted to show that NSCLC-H292 cells were blocked in the G0/G1 phase in the presence of compound 15, thus inhibiting the proliferation of tumor cells.Conclusion: This study has revealed that compound 15 is a promising antitumor lead due to the cytotoxic potencies and the high selectivity it displayed when compared to natural counterparts.Keywords: neolaxiflorin B inspired compounds, unsaturated ketone, antitumor activity

Hongrong Xu,1,* Lei Sheng,1,* Weili Chen,1 Fei Yuan,1 Mengjie Yang,1 Hui Li,1 Xuening Li,1 John Choi,2 Guiyu Zhao,2 Tianxin Hu,2 Yongguo Li,2 Yi Zhang,2 Li Chen2 1Department of Clinical Pharmacology, Zhongshan Hospital, Fudan University, Shanghai, 2Department of Clinical Research & Development, Hua Medicine, Shanghai, People’s Republic of China *These authors have contributed equally to this work Background: HMS5552, a novel fourth-generation glucokinase (GK) activator, has demonstrated promising effects on glycemic control in preclinical models of type 2 diabetes. This single ascending dose study was conducted to investigate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of HMS5552 during its first-in-human exposure.Methods: Sixty healthy subjects were enrolled. In each of six dose-cohorts (5, 10, 15, 25, 35, and 50 mg), ten subjects were randomized with eight subjects receiving the same cohort-dose of HMS5552 and two receiving placebo. Plasma HMS5552 exposure, glucose, and insulin were measured repeatedly during fasting and after a standardized meal. Assessment included safety, PK, and PD endpoints.Results: HMS5552 showed dose-proportional increases in area under the curve 0 to the last quantifiable concentration (AUC0–t) and maximum plasma concentration (Cmax). Slopes estimated by linear regression for AUC0–t and Cmax were ~1.0 (0.932 and 0.933, respectively). Geometric mean elimination half-life ranged from 4.48 to 7.51 hours and apparent clearance ranged from 11.5 to 13.1 L/h across all doses. No significant sex effect was observed in PK parameters. HMS5552 also demonstrated dose-related PD responses in terms of maximum glucose change from baseline (%) and mean glucose area under effect curve 0–4 hours change from baseline (%) (P

Reactor neutrino experiments play a crucial role in advancing our knowledge of neutrinos. In this Letter, the evolution of the flux and spectrum as a function of the reactor isotopic content is reported in terms of the inverse-beta-decay yield at Daya Bay with 1958 days of data and improved systematic uncertainties. These measurements are compared with two signature model predictions: the Huber-Mueller model based on the conversion method and the SM2018 model based on the summation method. The measured average flux and spectrum, as well as the flux evolution with the ^{239}Pu isotopic fraction, are inconsistent with the predictions of the Huber-Mueller model. In contrast, the SM2018 model is shown to agree with the average flux and its evolution but fails to describe the energy spectrum. Altering the predicted inverse-beta-decay spectrum from ^{239}Pu fission does not improve the agreement with the measurement for either model. The models can be brought into better agreement with the measurements if either the predicted spectrum due to ^{235}U fission is changed or the predicted ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu spectra are changed in equal measure.

We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3}  eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3}  eV^{2} for the inverted mass ordering.

This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12 MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10 MeV is rejected with a significance of 6.2 standard deviations. A 29% antineutrino flux deficit in the prompt energy region of 8-11 MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-Q_{β} isotopes in commercial reactors.

The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era. The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment, in combination with the fission rates of fissile isotopes in the reactor, is used to extract the positron energy spectra resulting from the fission of specific isotopes. This information can be used to produce a precise, data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay. The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method. Consistent results are obtained with other unfolding methods. A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated. Given the reactor fission fractions, the technique can predict the energy spectrum to a 2% precision. In addition, we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.

The establishment of a possible connection between neutrino emission and gravitational-wave (GW) bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge. In the Daya Bay experiment, using the data collected from December 2011 to August 2017, a search was performed for electron-Antineutrino signals that coincided with detected GW events, including GW150914, GW151012, GW151226, GW170104, GW170608, GW170814, and GW170817. We used three time windows of 10, 500, and 1000 s relative to the occurrence of the GW events and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates. The detected electron-Antineutrino candidates were consistent with the expected background rates for all the three time windows. Assuming monochromatic spectra, we found upper limits (90% confidence level) of the electron-Antineutrino fluence of (1.13-2.44)×1011 cm-2 at 5 MeV to 8.0×107 cm-2 at 100 MeV for the three time windows. Under the assumption of a Fermi-Dirac spectrum, the upper limits were found to be (5.4-7.0)×109 cm-2 for the three time windows.

The prediction of reactor antineutrino spectra will play a crucial role asreactor experiments enter the precision era. The positron energy spectrum of3.5 million antineutrino inverse beta decay reactions observed by the Daya Bayexperiment, in combination with the fission rates of fissile isotopes in thereactor, is used to extract the positron energy spectra resulting from thefission of specific isotopes. This information can be used to produce aprecise, data-based prediction of the antineutrino energy spectrum in otherreactor antineutrino experiments with different fission fractions than DayaBay. The positron energy spectra are unfolded to obtain the antineutrino energyspectra by removing the contribution from detector response with the Wiener-SVDunfolding method. Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrinoenergy spectrum is proposed and investigated. Given the reactor fissionfractions, the technique can predict the energy spectrum to a 2% precision. Inaddition, we illustrate how to perform a rigorous comparison between theunfolded antineutrino spectrum and a theoretical model prediction that avoidsthe input model bias of the unfolding method.

A high precision calibration of the nonlinearity in the energy response of the Daya Bay Reactor Neutrino Experiment's antineutrino detectors is presented in detail. The energy nonlinearity originates from the particle-dependent light yield of the scintillator and charge-dependent electronics response. The nonlinearity model is constrained by γ calibration points from deployed and naturally occurring radioactive sources, the β spectrum from 12B decays, and a direct measurement of the electronics nonlinearity with a new flash analog-to-digital converter readout system. Less than 0.5% uncertainty in the energy nonlinearity calibration is achieved for positrons of kinetic energies greater than 1 MeV.

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.

This work reports a precise measurement of the reactor antineutrino flux using 2.2 million inverse beta decay (IBD) events collected with the Daya Bay near detectors in 1230 days. The dominant uncertainty on the neutron detection efficiency is reduced by 56% with respect to the previous measurement through a comprehensive neutron calibration and detailed data and simulation analysis. The new average IBD yield is determined to be (5.91±0.09)×10-43 cm2/fission with total uncertainty improved by 29%. The corresponding mean fission fractions from the four main fission isotopes U235, U238, Pu239, and Pu241 are 0.564, 0.076, 0.304, and 0.056, respectively. The ratio of measured to predicted antineutrino yield is found to be 0.952±0.014±0.023 (1.001±0.015±0.027) for the Huber-Mueller (ILL-Vogel) model, where the first and second uncertainty are experimental and theoretical model uncertainty, respectively. This measurement confirms the discrepancy between the world average of reactor antineutrino flux and the Huber-Mueller model.

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.

The Daya Bay Collaboration responds to comments posted by S. Parke and R.Zukanovich Funchal regarding our use of Delta(m^2_ee).

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.

A search for a time-varying νe signal was performed with 621 days of data acquired by the Daya Bay Reactor Neutrino Experiment over 704 calendar days. The time spectrum of the measured νe flux normalized to its prediction was analyzed with a Lomb-Scargle periodogram, which yielded no significant signal for periods ranging from 2 hours to nearly 2 years. The normalized time spectrum was also fit for a sidereal modulation under the Standard Model Extension (SME) framework to search for Lorentz and CPT violation (LV-CPTV). Limits were obtained for all six flavor pairs ēμ,ēτ, μτ, ēē,μμ and ττ by fitting them one at a time, constituting the first experimental constraints on the latter three. Daya Bay's high statistics and unique layout of multiple directions from three pairs of reactors to three experimental halls allowed the simultaneous constraint of individual SME LV-CPTV coefficients without assuming others contribute negligibly, a first for a neutrino experiment.

Neutrons produced by cosmic ray muons are an important background forunderground experiments studying neutrino oscillations, neutrinoless doublebeta decay, dark matter, and other rare-event signals. A measurement of theneutron yield in the three different experimental halls of the Daya Bay ReactorNeutrino Experiment at varying depth is reported. The neutron yield in DayaBay's liquid scintillator is measured to be $Y_n=(10.26\pm 0.86)\times10^{-5}$, $(10.22\pm 0.87)\times 10^{-5}$, and $(17.03\pm 1.22)\times10^{-5}~\mu^{-1}~$g$^{-1}~$cm$^2$ at depths of 250, 265, and 860meters-water-equivalent. These results are compared to other measurements andthe simulated neutron yield in Fluka and Geant4. A global fit including theDaya Bay measurements yields a power law coefficient of $0.77 \pm 0.03$ for thedependence of the neutron yield on muon energy.

The Daya Bay Experiment consists of eight identically designed detectors located in three underground experimental halls named as EH1, EH2, EH3, with 250, 265 and 860 meters of water equivalent vertical overburden, respectively. Cosmic muon events have been recorded over a two-year period. The underground muon rate is observed to be positively correlated with the effective atmospheric temperature and to follow a seasonal modulation pattern. The correlation coefficient α, describing how a variation in the muon rate relates to a variation in the effective atmospheric temperature, is found to be αEH1 = 0.362±0.031, αEH2 = 0.433±0.038 and αEH3 = 0.641±0.057 for each experimental hall.

The disappearance of reactor $\bar{\nu}_e$ observed by the Daya Bayexperiment is examined in the framework of a model in which the neutrino isdescribed by a wave packet with a relative intrinsic momentum dispersion$\sigma_\text{rel}$. Three pairs of nuclear reactors and eight antineutrinodetectors, each with good energy resolution, distributed among threeexperimental halls, supply a high-statistics sample of $\bar{\nu}_e$ acquiredat nine different baselines. This provides a unique platform to test theeffects which arise from the wave packet treatment of neutrino oscillation. Themodified survival probability formula was used to fit Daya Bay data, providingthe first experimental limits: $2.38 \cdot 10^{-17} < \sigma_{\rm rel} < 0.23$.Treating the dimensions of the reactor cores and detectors as constraints, thelimits are improved: $10^{-14} \lesssim \sigma_{\rm rel} < 0.23$, and an upperlimit of $\sigma_{\rm rel}

The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW_{th} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective ^{239}Pu fission fractions F_{239} from 0.25 to 0.35, Daya Bay measures an average IBD yield σ[over ¯]_{f} of (5.90±0.13)×10^{-43}  cm^{2}/fission and a fuel-dependent variation in the IBD yield, dσ_{f}/dF_{239}, of (-1.86±0.18)×10^{-43}  cm^{2}/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the ^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield is found to be energy dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes ^{235}U, ^{239}Pu, ^{238}U, and ^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10^{-43}  cm^{2}/fission have been determined for the two dominant fission parent isotopes ^{235}U and ^{239}Pu. A 7.8% discrepancy between the observed and predicted ^{235}U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.

A measurement of electron antineutrino oscillation by the Daya Bay Reactor Neutrino Experiment is described in detail. Six 2.9-GWth nuclear power reactors of the Daya Bay and Ling Ao nuclear power facilities served as intense sources of νe's. Comparison of the νe rate and energy spectrum measured by antineutrino detectors far from the nuclear reactors (∼1500-1950 m) relative to detectors near the reactors (∼350-600 m) allowed a precise measurement of νe disappearance. More than 2.5 million νe inverse beta-decay interactions were observed, based on the combination of 217 days of operation of six antineutrino detectors (December, 2011-July, 2012) with a subsequent 1013 days using the complete configuration of eight detectors (October, 2012-July, 2015). The νe rate observed at the far detectors relative to the near detectors showed a significant deficit, R=0.949±0.002(stat)±0.002(syst). The energy dependence of νe disappearance showed the distinct variation predicted by neutrino oscillation. Analysis using an approximation for the three-flavor oscillation probability yielded the flavor-mixing angle sin22θ13=0.0841±0.0027(stat)±0.0019(syst) and the effective neutrino mass-squared difference of |Δmee2|=(2.50±0.06(stat)±0.06(syst))×10-3 eV2. Analysis using the exact three-flavor probability found Δm322=(2.45±0.06(stat)±0.06(syst))×10-3 eV2 assuming the normal neutrino mass hierarchy and Δm322=(-2.56±0.06(stat)±0.06(syst))×10-3 eV2 for the inverted hierarchy.

A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GWth nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946±0.020 (0.992±0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4-6 MeV was found in the measured spectrum, with a local significance of 4.4σ. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2×10^{-4}≲|Δm_{41}^{2}|≲0.3  eV^{2} mass range. The resulting limits on sin^{2}2θ_{14} are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm_{41}^{2}|≲0.2  eV^{2} region.

This article reports an improved independent measurement of neutrino mixing angle θ13 at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β-decays with the emitted neutron captured by hydrogen, yielding a data set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced Li9 and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin22θ13=0.071±0.011 in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.

This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18)  cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43)  cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th}  ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3}  eV^{2} in the three-neutrino framework.

A new measurement of the $\theta_{13}$ mixing angle has been obtained at theDaya Bay Reactor Neutrino Experiment via the detection of inverse beta decaystagged by neutron capture on hydrogen. The antineutrino events for hydrogencapture are distinct from those for gadolinium capture with largely differentsystematic uncertainties, allowing a determination independent of thegadolinium-capture result and an improvement on the precision of $\theta_{13}$measurement. With a 217-day antineutrino data set obtained with sixantineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficitobserved at the far hall is interpreted as $\sin^22\theta_{13}=0.083\pm0.018$in the three-flavor oscillation model. When combined with thegadolinium-capture result from Daya Bay, we obtain$\sin^22\theta_{13}=0.089\pm0.008$ as the final result for thesix-antineutrino-detector configuration of the Daya Bay experiment.

A new measurement of the $\theta_{13}$ mixing angle has been obtained at theDaya Bay Reactor Neutrino Experiment via the detection of inverse beta decaystagged by neutron capture on hydrogen. The antineutrino events for hydrogencapture are distinct from those for gadolinium capture with largely differentsystematic uncertainties, allowing a determination independent of thegadolinium-capture result and an improvement on the precision of $\theta_{13}$measurement. With a 217-day antineutrino data set obtained with sixantineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficitobserved at the far hall is interpreted as $\sin^22\theta_{13}=0.083\pm0.018$in the three-flavor oscillation model. When combined with thegadolinium-capture result from Daya Bay, we obtain$\sin^22\theta_{13}=0.089\pm0.008$ as the final result for thesix-antineutrino-detector configuration of the Daya Bay experiment.

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

The Daya Bay Reactor Neutrino Experiment was designed to achieve a sensitivity on the value of sin22θ13 to better than 0.01 at 90% CL. The experiment consists of eight antineutrino detectors installed underground at different baselines from six nuclear reactors. With data collected with six antineutrino detectors for 55 days, Daya Bay announced the discovery of a non-zero value for sin22θ13 with a significance of 5.2 standard deviations in March 2012. The most recent analysis with 139 days of data acquired in a six-detector configuration yields sin22θ13=0.089±0.010(stat.)±0.005(syst.), which is the most precise measurement of sin22θ13 to date. © 2013.

The Daya Bay reactor antineutrino experiment is designed to make a precision measurement of the neutrino mixing angle θ13, and recently made the definitive discovery of its non-zero value. It utilizes a set of eight, functionally identical antineutrino detectors to measure the reactor flux and spectrum at baselines of ∼ 300-2000 m from the Daya Bay and Ling Ao Nuclear Power Plants. The Daya Bay antineutrino detectors were built in an above-ground facility and deployed side-by-side at three underground experimental sites near and far from the nuclear reactors. This configuration allows the experiment to make a precision measurement of reactor antineutrino disappearance over km-long baselines and reduces relative systematic uncertainties between detectors and nuclear reactors. This paper describes the assembly and installation of the Daya Bay antineutrino detectors. © 2013 IOP Publishing Ltd and Sissa Medialab srl.

We report an improved measurement of the neutrino mixing angle θ13 from the Daya Bay Reactor Neutrino Experiment. We exclude a zero value for sin22θ13 with a significance of 7.7 standard deviations. Electron antineutrinos from six reactors of 2.9 GW th were detected in six antineutrino detectors deployed in two near (flux-weighted baselines of 470 m and 576 m) and one far (1648 m) underground experimental halls. Using 139 days of data, 28909 (205308) electron antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to the expected number of antineutrinos assuming no oscillations at the far hall is 0.944±0.007(stat.)±0.003(syst.). An analysis of the relative rates in six detectors finds sin22θ13=0. 089±0.010(stat.)±0.005(syst.) in a three-neutrino framework. © 2013 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

Radiative decays of the radially excited charmonium resonance, (Formula presented) into (Formula presented) (Formula presented) and (Formula presented) final states have been measured in a sample of (Formula presented) (Formula presented) events collected by the BES Collaboration. The branching ratios (Formula presented) and (Formula presented) are obtained. When compared to the corresponding radiative (Formula presented) decays, the observed (Formula presented) radiative decay rates into (Formula presented) and (Formula presented) are consistent with the prediction of the “12%” rule. © 2003 The American Physical Society.

Radiative decays of the radially excited charmonium resonance, (Formula presented) into (Formula presented) (Formula presented) and (Formula presented) final states have been measured in a sample of (Formula presented) (Formula presented) events collected by the BES Collaboration. The branching ratios (Formula presented) and (Formula presented) are obtained. When compared to the corresponding radiative (Formula presented) decays, the observed (Formula presented) radiative decay rates into (Formula presented) and (Formula presented) are consistent with the prediction of the “12%” rule. © 2003 The American Physical Society.

The branching fraction of the ψ(2S) decay into τ+τ - has been measured for the first time using the BES detector at the Beijing Electron-Positron Collider. The result is Bττ=(2.710. 43±0.55)× 10-3, where the first error is statistical and the second is systematic. This value, along with those for the branching fractions into e+e- and μ+ μ- of this resonance, satisfy well the relation predicted by the sequential lepton hypothesis. Combining all these values with the leptonic width of the resonance, the total width of the ψ(25) is determined to be (252±37) keV. ©2002 The American Physical Society.

The Beijing Spectrometer (BES) detector is a general purpose solenoid detector at the Beijing Electron Positron Collider in Beijing, China. The recent upgrade of the initial BES detector to the improved BES II detector is described. A new drift chamber, time-of-flight counter, luminosity monitor compatible with a low-β lattice was built as well as the vertex chamber.

The Beijing Spectrometer (BES) detector is a general purpose solenoid detector at the Beijing Electron Positron Collider in Beijing, China. The recent upgrade of the initial BES detector to the improved BES II detector is described. A new drift chamber, time-of-flight counter, luminosity monitor compatible with a low-β lattice was built as well as the vertex chamber.

The first measurement of (Formula presented) and an upper limit for (Formula presented) are determined from 22.3 (Formula presented) of (Formula presented) annihilation data at a c.m. energy of 4.03 GeV. The data were recorded by the Beijing Spectrometer (BES) at BEPC. A recoil charge method is applied to charm threshold data to determine the charge of the D meson in the recoil from (Formula presented) reconstructed (Formula presented) (Formula presented) mesons. The branching fractions (Formula presented) and (Formula presented) are determined from 10 events with a reconstructed D and a recoiling (Formula presented) In addition, a 90% C.L. upper limit of (Formula presented) is determined from a search for semileptonic decays of the (Formula presented) © 2000 The American Physical Society.

Using a sample of 3.8 M (Formula presented) events accumulated with the BES detector, the process (Formula presented) is studied. The angular distributions are compared with the general decay amplitude analysis of Cahn. We find that the dipion system requires some D wave amplitude, as well as S wave. On the other hand, the (Formula presented) relative angular momentum is consistent with being pure S wave. The decay distributions have been fit to heavy quarkonium models, including the Novikov-Shifman model. This model, which is written in terms of the parameter (Formula presented) predicts that D wave pions should be present. We determine (Formula presented) based on the joint (Formula presented) distribution. The fraction of D wave amplitude as a function of (Formula presented) is found to decrease with increasing (Formula presented) in agreement with the model. We have also fit the Mannel-Yan model, which is another model that allows D wave pions. © 2000 The American Physical Society.

The cross section for charmed meson production at √s=4.03 and 4.14 GeV has been measured with the Beijing Spectrometer. The measurement was made using 22.3 pb-1 of e+e- data collected at 4.03 GeV and 1.5 pb-1 of e+e- data collected at 4.14 GeV. Inclusive observed cross sections for the production of charged and neutral D mesons and momentum spectra are presented. Observed cross sections were radiatively corrected to obtain tree level cross sections. Measurements of the total hadronic cross section are obtained from the charmed meson cross section and an extrapolation of results from below the charm threshold. ©2000 The American Physical Society.