Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays¹. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.

[Effect of acupuncture on pain and cerebral hemodynamics in patients with migraine: a randomized controlled trial]

OBJECTIVE

To observe the therapeutic effect between acupuncture combined with medication and simple medication on migraine and cerebral hemodynamics.

METHODS

A total of 120 patients with migraine were randomized into an acupuncture plus medication group (60 cases, 3 cases dropped off) and a medication group (60 cases, 6 cases dropped off). In the medication group, flunarizine hydrochloride capsule was given orally before sleep, 10 mg a day. On the basis of the treatment in the medication group, acupuncture was applied at Sizhukong (TE 23), Shuaigu (GB 8), Taiyang (EX-HN 5), Fengchi (GB 20) and etc. in the acupuncture plus medication group, 30 min each time, once a day. Treatment for 4 weeks was required in both groups. Before and after treatment, the visual analogue scale (VAS) score, indexes of cerebral hemodynamic [blood flow velocity of anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA), vertebral artery (VA) and basilar artery (BA)] and total TCM syndrome score were observed, and the clinical therapeutic effect and the incidence of the adverse events were evaluated in both groups.

RESULTS

Compared before treatment, the VAS scores, the blood flow velocity of ACA, MCA, PCA, VA, BA and the total TCM syndrome scores were decreased in both groups (P<0.05). After treatment, the VAS score, the blood flow velocity of ACA, MCA, PCA, VA, BA and the total TCM syndrome score in the acupuncture plus medication group were lower than those in the medication group (P<0.05). The total effective rate was 96.5% (55/57) in the acupuncture plus medication group, which was superior to 90.7% (49/54) in the medication group (P<0.05). There was no statistical difference in the incidence of adverse events between the two groups (P>0.05).

CONCLUSION

Acupuncture combined with flunarizine hydrochloride capsule can effectively relieve the pain in patients with migraine, reduce the cerebral blood flow velocity, the efficacy is superior to simple flunarizine hydrochloride capsule.

Transcatheter Closure of Perimembranous Ventricular Septal Defects Using Dual Wire-Maintaining Technique

OBJECTIVE

The present study was designed to evaluate the safety and feasibility of transcatheter closure of perimembranous ventricular septal defects (PmVSDs) with dual wire-maintaining technique (DWMT).

PATIENTS/METHODS

From January 2010 to December 2013, a total of 241 patients (men: 109, women: 132; mean age: 22.2±15.4 years) with congenital PmVSDs were randomised to either the conventional technique (CT) group (n=118) or the DWMT group (n=123).

RESULTS

In the CT group, the track wire was withdrawn before occluder insertion. In the DWMT group, the track wire was maintained in the delivery sheath during the procedure. Both the procedure time and fluoroscope time were reduced significantly in the DWMT group patients who required device replacement compared with CT group patients (median time: 46.0±14.8min vs. 56.0±15.2min, p<0.05; 15.0±11.6min vs. 22.0±10.1min, p<0.05). There was no difference in the incidence of complications between the two groups.

CONCLUSION

The DWMT is safe and feasible for transcatheter treatment of PmVSDs, especially in patients requiring device replacement, for it avoids reconstruction of the "arteriovenous wire loop", left ventriculography from the contralateral femoral route, or the use of a larger femoral artery short sheath.

Overexpression of G100S mutation in PRKAG2 causes Wolff-Parkinson-White syndrome in zebrafish

The Wolff-Parkinson-White (WPW) syndrome was believed to be associated with PRKAG2 gene mutations. In this study, we verified the pathopoiesis of G100S mutation, a novel mutation only discovered in Chinese patients with WPW, in cardiac disorder. Similar to R302Q, when overexpressed PRKAG2 G100S mutant in zebrafish, we observed a thicker heart wall, detected a decreased AMPK enzymatic activity by tissue AMPK kinase activity colorimetric technique, as well as examined an increased glycogen storage in heart wall using the method for periodic acid-Schiff staining, in comparison with the zebrafish without exogenous PRKAG2 (mock) or with wild-type PRKAG2 (WT). Taken together, we concluded PRKAG2 G100S mutation might contribute to impair the AMP-activated protein kinase function, which resulted in increased cardiac glycogen storage, serving as a pathogenesis for WPW syndrome in Chinese.

Vascular smooth muscle cell proliferation is influenced by let-7d microRNA and its interaction with KRAS

BACKGROUND

Several microRNAs (miRNAs) have been reported to regulate cardiovascular biological and pathological processes through inhibiting the translation of certain RNA transcripts. However, little is known about the association between miRNAs and vascular smooth muscle cell (VSMC) proliferation. The aim was to investigate the role of miRNAs in VSMC growth and the potential mechanism.

METHODS AND RESULTS

Primary VSMCs were isolated from the medial layer of the thoracic aorta obtained from spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). miRNA microarrays were used to analyze the difference in miRNA expression between VSMCs of SHR and WKY rats and were validated using TaqMan real-time PCR. Of the potentially related genes under the influence of let-7d identified through literature search, KRAS was verified by western blot and functionally analyzed using miRNA mimics transfection and analysis of transfectants by cell enumeration was made using CCK-8 and flow cytometric analysis of cell cycle progression. let-7d-transfected VSMCs from SHR, WKY and human coronary arteries expressed significantly lower amounts of KRAS protein, displayed reduced cell growth and led to a greater number of cells in the G1 phase than the G2/M phases of the cell cycle.

CONCLUSIONS

let-7d was significantly downregulated in VSMCs as an important regulator of cell proliferation. RAS might be involved in the proliferation regulation by let-7d.

Transcatheter closure of perimembranous ventricular septal defects using a novel wire-maintaining technique

OBJECTIVES

We aimed to evaluate the clinical feasibility and safety of a novel wire-maintaining technique (WMT) for transcatheter closure of perimembranous ventricular septal defects (PmVSDs).

BACKGROUND

Transcatheter device closure of PmVSDs has been increasingly performed and this procedure is now offered as primary therapy at many institutions.

METHODS

A total of 103 patients with complex PmVSDs were randomized to either the conventional technique (CT) group (n = 51) or the WMT group (n = 52). In the CT group, the track wire was withdrawn before the occluder insertion and deployment. If inappropriate, the initial occluder was withdrawn and the "arteriovenous wire loop" was re-established. In the WMT group, the track wire was maintained in the delivery sheath during the procedure. If the initial occluder was inappropriate, the delivery sheath could be reintroduced over the maintained wire.

RESULTS

For those patients who could not achieve optimal results with the initially selected occluders and required further device replacement, the procedure and fluoroscope time was reduced significantly in the WMT group compared with the CT group ([50.8 +/- 13.2] min vs. [61.5 +/- 15.4] min, P < 0.01 and [21.6 +/- 8.6] min vs. [27.3 +/- 7.4] min, P < 0.05; respectively). There was no difference in the incidence of complications of two groups.

CONCLUSIONS

The WMT was feasible and safe for the transcatheter treatment of PmVSDs, especially for those complex defects with great challenge. Using this novel technique, the reconstruction of "arteriovenous wire loop" could be avoided in patients requiring device replacement.