We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential ...cross sections of the reaction e^{+}e^{-}→nover ¯n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6 pb^{-1} in total at twelve center-of-mass energies between sqrts=2.0-2.95 GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrts=2.3935 GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.
BACKGROUND
The aim of this study was to investigate the effect of chromosomal polymorphic variations on the outcome of IVF and embryo transfer (IVF–embryo transfer) treatment for infertile couples.
...METHODS
During the period from October 2006 to December 2009, 1978 infertile couples who had received their first IVF–embryo transfer treatment cycle in our hospital were selected for this retrospective study, and the frequency of chromosomal polymorphic variations was calculated. From these, 1671 couples were selected and divided into three groups: 1402 couples with normal chromosomes (Group 1/control group), 82 couples with chromosomal polymorphic variations in only females (Group 2) and 187 couples with chromosomal polymorphic variations in only males (Group 3). The clinical pregnancy rates (CPR), early miscarriage rates and ongoing pregnancy rates after IVF–embryo transfer treatment were compared.
RESULTS
There were no statistically significant differences among the three groups in implantation rates (29.37% in the control group, 29.70% in Group 2 and 31.41% in Group 3, P > 0.05) and CPR (45.86, 46.34 and 51.87%, respectively, P > 0.05). Although there was a trend toward higher first trimester pregnancy loss rates in Group 3 (male chromosomal polymorphic variations), but not in Group 2, compared with normal karyotype couples (10.31 versus 6.84%), the difference did not reach significance (P > 0.05).
CONCLUSIONS
Chromosomal polymorphic variations appear to have no adverse effects on the outcome of IVF–embryo transfer treatment.
Using 2.93 fb −1 of e+e− collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector, we report the first measurements of the absolute branching fractions of 14 hadronic ...D0(+) decays to exclusive final states with an η , e.g., D0 → K−π+η , K0Sπ0η , K+K−η , K0SK0Sη, K−π+π0η , K0Sπ+π−η , K0Sπ0π0η , and π+π−π0η ; D+ → K0Sπ+η,K0SK+η, K−π+π+η, K0Sπ+π0η, π+π+π−η , and π+π0π0η. Among these decays, the D0 → K−π+η and D+→K0Sπ+η decays have the largest branching fractions, which are B (D0 → K−π+η) = ( 1.853 ± 0.02 5 stat ± 0.03 1 syst ) % and B ( D+ → K0Sπ+η ) = ( 1.309 ± 0.03 7 stat ± 0.03 1 syst ) % , respectively. The charge-parity asymmetries for the six decays with highest event yields are determined, and no statistically significant charge-parity violation is found.
Combining transmission electron microscopes and density functional theory calculations, we report the nucleation and growth mechanisms of room temperature rolling induced face-centered cubic titanium ...(fcc-Ti) in polycrystalline hexagonal close packed titanium (hcp-Ti). Fcc-Ti and hcp-Ti take the orientation relation: 〈0001〉hcp||〈001〉fcc and , different from the conventional one. The nucleation of fcc-Ti is accomplished via pure-shuffle mechanism with a minimum stable thickness of three atomic layers, and the growth via shear-shuffle mechanisms through gliding two-layer disconnections or pure-shuffle mechanisms through gliding four-layer disconnections. Such phase transformation offers an additional plastic deformation mode comparable to twinning.
Abstract
The interaction between the solar wind and the magnetosphere is one of the most important research subjects in the fields of astrophysics and space physics. For more than half a century, ...based on the pressure balance assumption between the solar wind and the magnetosphere and considering other important factors, such as the interplanetary magnetic field and magnetic reconnection process, the dynamic processes at the magnetopause have been extensively analyzed. However, the responses of magnetopause to the solar wind dynamic pressure variations are still complicated to understand. Here, we show that the interaction between the solar wind and the magnetosphere can be regarded as a quasi-elastodynamic process. The driving frequency of the solar wind is determined as a crucial reason for the phase difference between solar wind dynamic pressure variations and magnetopause standoff distance. The low-pass filter effect and oscillation properties of the magnetopause can also be well explained by the forced damped vibrations. Moreover, the quasi-elastodynamic processes predict deformations at the magnetopause, which resemble the magnetopause surface wave. Finally, a three-dimensional time-dependent magnetopause model is constructed and verified by observation. Based on 12,242 magnetopause crossing events, it is found that the new model reveals ∼9.7% better prediction accuracy than the widely used time-independent model. These results can also shed light on our understanding of the solar-wind–magnetopause interaction for other planets.
Observation of e+e- → γX(3872) at BESIII Achasov, M N; Albayrak, O; Ambrose, D J ...
Physical review letters,
2014-Mar-07, Letnik:
112, Številka:
9
Journal Article
Recenzirano
Odprti dostop
With data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.009 to 4.420 GeV, the process e+e-→ γX(3872) is observed for the first time ...with a statistical significance of 6.3σ. The measured mass of the X(3872) is (3871.9 ± 0.7s tat ± 0.2 syst) MeV/c(2), in agreement with previous measurements. Measurements of the product of the cross section σe+e- → γX(3872) and the branching fraction BX(3872)→π+π-J/ψ at center-of-mass energies 4.009, 4.229, 4.260, and 4.360 GeV are reported. Our measurements are consistent with expectations for the radiative transition process Y(4260) → γX(3872).
A series of Ce-incorporated SBA-15 mesoporous materials were synthesized through direct hydrothermal synthesis method and further impregnated with 12 wt.% Ni. The samples were characterized by ...ICP-AES, XRD, N
2 physisorption, XPS, TPR, H
2 chemisorption, TGA, temperature-programmed hydrogenation (TPH) and TEM measurements. The low-angle XRD and N
2 physisorption results showed the Ce successfully incorporated into the framework of SBA-15. The catalytic properties of these catalysts were investigated in methane reforming with CO
2. The Ce/Si molar ratio had a significant influence on the catalytic performance. The highest catalytic activity and long-term stability were obtained over the Ni/Ce-SBA-15 (Ce/Si = 0.04) sample. The improved catalytic behavior could be attributed to the cerium impact in the framework of SBA-15, where cerium promoted the dispersion of nano-sized Ni species and inhibited the carbon formation. In comparison with the effect of CeO
2 crystallites in SBA-15, cerium in the framework of SBA-15 promoted the formation of the nickel metallic particles with smaller size. The XRD and TGA results exhibited that carbon deposition was responsible for activity loss of Ni/SBA-15 and Ni/Ce-SBA-15 (Ce/Si = 0.06) catalysts. TEM results showed that the hexagonal mesopores of SBA-15 were still kept intact after reaction and the pore walls of SBA-15 prevented the aggregation of nickel.
Daily PM
2.5 and water-soluble inorganic ions (Na
+, NH
4
+, K
+, Mg
2+, Ca
2+, Cl
−, NO
3
− and SO
4
2−) were collected in Xi'an (34.23°N, 108.88°E), China from March 2006 to March 2007. PM
2.5 was ...collected using battery-powered mini-volume samplers. And the ions were determined by ion chromatography from the measured aerosol mass. The annual average mass concentration of PM
2.5 was found to be 194.1
±
78.6
μg
m
−
3
, which exceeded substantially the international guidelines for health concerns. The seasonal average mass concentration of PM
2.5 was highest in winter (266.8
μg
m
−
3
) and lowest in summer (138.6
μg
m
−
3
). The three highest abundant ions were SO
4
2−, NO
3
−, and NH
4
+, with average concentrations of 35.6
±
19.5
μg
m
−
3
, 16.4
±
10.1
μg
m
−
3
, and 11.4
±
6.8
μg
m
−
3
, which were accounted for 18.7%, 8.0%, and 5.7% of the PM
2.5 mass, respectively. The major ions were in the species of (NH
4)
2SO
4, NH
4HSO
4 and NH
4NO
3, and their concentrations were highest in winter, due to high coal combustion. The concentrations of Ca
2+ were higher in spring than other seasons, due to the higher mineral dust concentrations. Ca
2+ was strongly correlated with CO
3
2−, which was calculated as the difference in the measured cations minus anions. Ion balance calculations indicate that the PM
2.5 was acidic, and this result is consistent with the measurement of pH values. Sulfur oxidation ratio was higher in summer and autumn, which implies that the formation of secondary sulfate-rich particles is favored by warm and relatively moist weather. Nitrogen oxidation ratio was highest in autumn.
► Coal combustion has heavy impact on the variations of water-soluble ions. ► PM
2.5 in non-spring was acidic, while the aerosol was less acidic and possibly even alkaline in spring due to the buffering effects of mineral dust. ► Relationship between CO
3
2- and Ca
2+ implies that Ca
2CO
3 was the major form for the aerosol carbonate.
We theoretically study field-induced domain wall motion in an electrically insulating ferromagnet with hard- and easy-axis anisotropies. Domain walls can propagate along a dissipationless wire ...through spin wave emission locked into the known soliton velocity at low fields. In the presence of damping, the usual Walker rigid-body propagation mode can become unstable for a magnetic field smaller than the Walker breakdown field.
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