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 study the process e^{+}e^{-}→Λ_{c}^{+}Λover ¯_{c}^{-} at twelve center-of-mass energies from 4.6119 to 4.9509 GeV using data samples collected by the BESIII detector at the BEPCII collider. The ...Born cross sections and effective form factors (|G_{eff}|) are determined with unprecedented precision after combining the single and double-tag methods based on the decay process Λ_{c}^{+}→pK^{-}π^{+}. Flat cross sections around 4.63 GeV are obtained and no indication of the resonant structure Y(4630), as reported by Belle, is found. In addition, no oscillatory behavior is discerned in the |G_{eff}| energy dependence of Λ_{c}^{+}, in contrast to what is seen for the proton and neutron cases. Analyzing the cross section together with the polar-angle distribution of the Λ_{c}^{+} baryon at each energy point, the moduli of electric and magnetic form factors (|G_{E}| and |G_{M}|) are extracted and separated. For the first time, the energy dependence of the form factor ratio |G_{E}/G_{M}| is observed, which can be well described by an oscillatory function.
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 ν¯e’s. Comparison of the ν¯e 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 ν¯e disappearance. More than 2.5 million ν¯e 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 ν¯e 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 ν¯e 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.
Background
Chronic sinusitis (CRS) is a common otorhinolaryngologic disease that is frequently encountered in everyday practice, but there is a lack of precise data regarding the prevalence of CRS in ...developing countries. We performed a national investigation in China to determine the prevalence and associated factors of CRS.
Methods
We conducted a cross‐sectional investigation in 2012. A stratified four‐stage sampling method was used to select participants randomly from seven cities in mainland China. All participants were interviewed face‐to‐face via a standardized questionnaire. Unconditional logistic regression analyses were conducted to examine the association between smoking and sinusitis after adjusting for socio‐demographic factors.
Results
This study included a total of 10 636 respondents from seven cities. The overall prevalence of CRS was 8.0% and ranged from 4.8% to 9.7% in seven centres. Chronic sinusitis affected approximately 107 million people in mainland China. Chronic sinusitis was particularly prevalent among people with specific medical conditions, including allergic rhinitis, asthma, chronic obstructive pulmonary disease and gout. The prevalence was slightly higher among males (8.79%) than females (7.28%) (P = 0.004), and the prevalence varied by age group, ethnicity and marital status and education (P < 0.05), but not by household per capita income or living space (P > 0.05). Both second‐hand tobacco smoke and active smoking were independent risk factors for CRS (P = 0.001).
Conclusions
Chronic sinusitis is an important public health problem in China. Our study provides important information for the assessment of the economic burden of CRS and the development and promotion of public health policies associated with CRS particularly in developing countries.
Background
According to some guidelines for the management of gastric cancer, adjuvant chemotherapy is recommended for patients with pT3–4 or node‐positive disease. The aim of this study was to ...define low‐ and high‐risk groups in terms of survival, and to predict the benefit of adjuvant fluoropyrimidine plus oxaliplatin (F‐OX) chemotherapy.
Methods
Patients with pT3–4 or node‐positive gastric cancer after gastrectomy with D2 lymphadenectomy between 2000 and 2013 were included. The performance of a previously published nomogram was assessed by discrimination and calibration. Patients were stratified into risk groups on the basis of the nomogram‐predicted overall survival probability. The efficacy of F‐OX within each risk subgroup was assessed using the log rank test and Cox regression analysis weighted by inverse propensity score.
Results
Some 1464 patients were included. The nomogram showed better discrimination than the seventh AJCC staging classification (concordance index 0·72 versus 0·68 respectively; P = 0·008) and accurate calibration. F‐OX was not associated with improved survival in patients in the low‐risk group, whereas it reduced the risk of death by over 20 per cent in the intermediate‐ and high‐risk groups (P = 0·036 and P < 0·001 respectively) (P for interaction = 0·014).
Conclusion
A nomogram can aid in individualized decision‐making regarding the administration of F‐OX after gastrectomy for cancer.
Facilitates individualized treatment
Recent studies indicated that high-entropy alloys (HEAs) possess unusual structural and thermal features, which could greatly affect dislocation motion and contribute to the mechanical performance, ...however, a HEA matrix alone is insufficiently strong for engineering applications and other strengthening mechanisms are urgently needed to be incorporated. In this work, we demonstrate the possibility to precipitate nanosized coherent reinforcing phase, i.e., L12-Ni3(Ti,Al), in a fcc-FeCoNiCr HEA matrix using minor additions of Ti and Al. Through thermomechanical processing and microstructure controlling, extraordinary balanced tensile properties at room temperature were achieved, which is due to a well combination of various hardening mechanisms, particularly precipitation hardening. The applicability and validity of the conventional strengthening theories are also discussed. The current work is a successful demonstration of using integrated strengthening approaches to manipulate the properties of fcc-HEA systems, and the resulting findings are important not only for understanding the strengthening mechanisms of metallic materials in general, but also for the future development of high-performance HEAs for industrial applications.
Through controlled thermomechanical processes and microstructure, extraordinary balanced tensile properties at room temperature were achieved via formation of a high density of nanosized coherent reinforcing phase, i.e., L12–Ni3(Ti,Al), in a fcc-FeCoNiCr high-entropy alloy matrix. Display omitted
Using
e
+
e
−
collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2595
)
−
+
c
.
c
.
and
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
...2625
)
−
+
c
.
c
.
are measured for the first time at center-of-mass energies of
s
=
4918.0
and 4950.9 MeV. Nonzero cross sections are observed very close to the production threshold. The measured Born cross sections of
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2625
)
−
+
c
.
c
.
are about 2–3 times greater than those of
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2595
)
−
+
c
.
c
.
, providing the similar behavior as semileptonic decays of
Λ
b
0
, but different behavior from that in the hadronic decays of
Λ
b
0
. The Born cross sections are
15.6
±
3.1
±
0.9
pb
and
29.4
±
3.7
±
2.7
pb
for
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2595
)
−
+
c
.
c
.
, and are
43.4
±
4.0
±
4.1
pb
and
76.8
±
6.5
±
4.2
pb
for
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2625
)
−
+
c
.
c
.
at
s
=
4918.0
and 4950.9 MeV, respectively. Based on the polar angle distributions of the
Λ
¯
c
(
2625
)
−
and
Λ
c
(
2625
)
+
, the form-factor ratios
|
G
E
|
2
+
3
|
G
M
|
2
/
|
G
C
|
are determined for
e
+
e
−
→
Λ
c
+
Λ
¯
c
(
2625
)
−
+
c
.
c
.
for the first time, which are
5.95
±
4.07
±
0.15
and
0.94
±
0.32
±
0.02
at
s
=
4918.0
and 4950.9 MeV, respectively. All of these first uncertainties are statistical and second systematic.
Published by the American Physical Society
2024
Based on a data sample of 10 billion
J
/
ψ
events collected with the BESIII detector, improved measurements of the Dalitz decays
η
/
η
′
→
γ
e
+
e
−
are performed, where the
η
and
η
′
are produced ...through the radiative decays
J
/
ψ
→
γ
η
/
η
′
. The branching fractions of
η
→
γ
e
+
e
−
and
η
′
→
γ
e
+
e
−
are measured to be
(
7.07
±
0.05
±
0.23
)
×
10
−
3
and
(
4.83
±
0.07
±
0.14
)
×
10
−
4
, respectively. Within the single-pole model, the parameter of electromagnetic transition form factor for
η
→
γ
e
+
e
−
is determined to be
Λ
η
=
(
0.749
±
0.027
±
0.007
)
GeV
/
c
2
. Within the multipole model, we extract the electromagnetic transition form factors for
η
′
→
γ
e
+
e
−
to be
Λ
η
′
=
(
0.802
±
0.007
±
0.008
)
GeV
/
c
2
and
γ
η
′
=
(
0.113
±
0.010
±
0.002
)
GeV
/
c
2
. The results are consistent with both theoretical predictions and previous measurements. The characteristic sizes of the interaction regions for the
η
and
η
′
are calculated to be
(
0.645
±
0.023
±
0.007
)
fm
and
(
0.596
±
0.005
±
0.006
)
fm
, respectively. In addition, we search for the dark photon in
η
/
η
′
→
γ
e
+
e
−
, and the upper limits of the branching fractions as a function of the dark photon are given at 90% confidence level.
Published by the American Physical Society
2024
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