In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy ...physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.
Summary
Background
Studies have showed that 10‐day sequential treatment regimen achieved higher Helicobacter pylori eradication rate than standard triple therapies.
Aim
To compare a 10‐day sequential ...therapy and standard triple therapy in Chinese children with H. pylori infection.
Methods
A prospective, multicentre, open‐label, randomised controlled trial was conducted in four tertiary medical centres in China. Children with H. pylori gastritis were randomly assigned to a 10‐day sequential therapy consisting of omeprazole and amoxicillin for 5 days followed by omeprazole, clarithromycin and metronidazole for the remaining 5 days, or 7‐day or 10‐day standard triple therapy comprising of omeprazole, amoxicillin and clarithromycin. H. pylori eradication was assessed by H. pylori stool antigen test.
Results
A total of 360 patients were included. The eradication rate achieved with the 10‐day sequential therapy was significantly higher than either the 7‐day or 10‐day standard triple treatment, either by the intention‐to‐treat analysis (81.4% vs. 61.9% or 67.7%, P < 0.05) or per‐protocol analysis (89.7% vs. 70.8% or 77.8%, P < 0.05).
Conclusions
The 10‐day sequential regimen was significantly more effective than standard 7‐day or 10‐day triple regimens in eradicating H. pylori infection in Chinese children.
Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances
. It has long been speculated that magnetars are the engine powering ...repeating bursts from FRB sources
, but no convincing evidence has been collected so far
. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts
. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare
. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.
Glycolysis is critical for cancer stem cell reprogramming; however, the underlying regulatory mechanisms remain elusive. Here, we show that pyruvate dehydrogenase kinase 1 (PDK1) is enriched in ...breast cancer stem cells (BCSCs), whereas depletion of PDK1 remarkably diminishes ALDH
subpopulations, decreases stemness-related transcriptional factor expression, and inhibits sphere-formation ability and tumor growth. Conversely, high levels of PDK1 enhance BCSC properties and are correlated with poor overall survival. In mouse xenograft tumor, PDK1 is accumulated in hypoxic regions and activates glycolysis to promote stem-like traits. Moreover, through screening hypoxia-related long non-coding RNAs (lncRNAs) in PDK1-positive tissue, we find that lncRNA H19 is responsible for glycolysis and BCSC maintenance. Furthermore, H19 knockdown decreases PDK1 expression in hypoxia, and ablation of PDK1 counteracts H19-mediated glycolysis and self-renewal ability in vitro and in vivo. Accordingly, H19 and PDK1 expression exhibits strong correlations in primary breast carcinomas. H19 acting as a competitive endogenous RNA sequesters miRNA let-7 to release Hypoxia-inducible factor 1α, leading to an increase in PDK1 expression. Lastly, aspirin markedly attenuates glycolysis and cancer stem-like characteristics by suppressing both H19 and PDK1. Thus, these novel findings demonstrate that the glycolysis gatekeeper PDK1 has a critical role in BCSC reprogramming and provides a potential therapeutic strategy for breast malignancy.
HIAF (High Intensity heavy ion Accelerator Facility), a new facility planned in China for heavy ion related researches, consists of two ion sources, a high intensity Heavy Ion Superconducting Linac ...(HISCL), a 45 Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage ring system. The key features of HIAF are unprecedented high pulse beam intensity and versatile operation mode. The HIAF project aims to expand nuclear and related researches into presently unreachable region and give scientists possibilities to conduct cutting-edge researches in these fields. The general description of the facility is given in this article with a focus on the accelerator design.
Using a low background data sample of 9.7×10^{5} J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII ...detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
► ET were measured for three years using EC and LAS at three sites over a basin. ► The seasonal and interannual variations of observed ET at two scales were analyzed. ► ET differences among the years ...and sites, from EC and LAS measurements were analyzed. ► ET measurements were compared to field water balance calculations and MODIS products.
Evapotranspiration (ET) observations were made for 3years (2008–2010), using eddy covariance (EC) systems and large aperture scintillometers (LAS), in typical underlying surfaces across the Hai River Basin: orchards (Miyun, MY), cropland in the suburbs (Daxing, DX), and cropland in the plains (Guantao, GT). Reliable data were obtained after carefully data processing, and the seasonal and interannual variability in ET was quantitatively analyzed. The annual ET during 2008–2010 ranged from 510–730mm for the EC measurements and 430–560mm for the LAS measurements. The differences in ET among the years and sites were connected with differences in soil moisture and crop growing conditions. The difference in the source areas of EC and LAS measurements and the heterogeneity in their source areas are the primary causes of the discrepancy between EC and LAS measurements. The EC and LAS measurements are compared to the field water balance method calculation and MOD16 ET (the MODIS ET product from the MODIS Global Evapotranspiration Project), respectively. The average difference was 0.85% (mean relative error) and 33.80mm (root mean square error) between the EC measurements and field water balance method calculations, and 7.72% and 47.08mm between LAS measurements and MOD16 ET from 2008 to 2010 at the three sites. We found a decreasing tendency for ET in the past 15years across the Hai River Basin, especially after the year of 2005.
The cross sections of e^{+}e^{-}→π^{+}π^{-}h_{c} at center-of-mass energies from 3.896 to 4.600 GeV are measured using data samples collected with the BESIII detector operating at the Beijing ...Electron Positron Collider. The cross sections are found to be of the same order of magnitude as those of e^{+}e^{-}→π^{+}π^{-}J/ψ and e^{+}e^{-}→π^{+}π^{-}ψ(2S), but the line shape is inconsistent with the Y states observed in the latter two modes. Two structures are observed in the e^{+}e^{-}→π^{+}π^{-}h_{c} cross sections around 4.22 and 4.39 GeV/c^{2}, which we call Y(4220) and Y(4390), respectively. A fit with a coherent sum of two Breit-Wigner functions results in a mass of (4218.4_{-4.5}^{+5.5}±0.9) MeV/c^{2} and a width of (66.0_{-8.3}^{+12.3}±0.4) MeV for the Y(4220), and a mass of (4391.5_{-6.8}^{+6.3}±1.0) MeV/c^{2} and a width of (139.5_{-20.6}^{+16.2}±0.6) MeV for the Y(4390), where the first uncertainties are statistical and the second ones systematic. The statistical significance of Y(4220) and Y(4390) is 10σ over one structure assumption.
Although the sun is really far away from us, some solar activities could still influence the performance and reliability of space-borne and ground-based technological systems on Earth. Those ...time-varying conditions in space caused by the sun are also called solar storm or space weather. It is known that aviation activities can be affected during solar storms, but the exact effects of space weather on aviation are still unclear. Especially how the flight delays, the top topic concerned by most people, will be affected by space weather has never been thoroughly researched. By analyzing huge amount of flight data (~ 4 × 10
records), for the first time, we quantitatively investigate the flight delays during space weather events. It is found that compared to the quiet periods, the average arrival delay time and 30-min delay rate during space weather events are significantly increased by 81.34% and 21.45% respectively. The evident negative correlation between the yearly flight regularity rate and the yearly mean total sunspot number during 22 years also confirms such correlation. Further studies show that the flight delay time and delay rate will monotonically increase with the geomagnetic field fluctuations and ionospheric disturbances. These results indicate that the interferences in communication and navigation during space weather events may be the most probable reason accounting for the increased flight delays. The above analyses expand the traditional field of space weather research and could also provide us with brand new views for improving the flight delay predications.
The spin and parity of the Z_{c}(3900)^{±} state are determined to be J^{P}=1^{+} with a statistical significance larger than 7σ over other quantum numbers in a partial wave analysis of the process ...e^{+}e^{-}→π^{+}π^{-}J/ψ. We use a data sample of 1.92 fb^{-1} accumulated at sqrts=4.23 and 4.26 GeV with the BESIII experiment. When parametrizing the Z_{c}(3900)^{±} with a Flatté-like formula, we determine its pole mass M_{pole}=(3881.2±4.2_{stat}±52.7_{syst}) MeV/c^{2} and pole width Γ_{pole}=(51.8±4.6_{stat}±36.0_{syst}) MeV. We also measure cross sections for the process e^{+}e^{-}→Z_{c}(3900)^{+}π^{-}+c.c.→J/ψπ^{+}π^{-} and determine an upper limit at the 90% confidence level for the process e^{+}e^{-}→Z_{c}(4020)^{+}π^{-}+c.c.→J/ψπ^{+}π^{-}.
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