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 plane3-6, 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.

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.

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.

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.

[Analysis of influencing factors of high-frequency hearing loss among male noise workers in an automobile manufacturing enterprise].

Objective: To analysis of high-frequency hearing loss status and risk factors among male noise workers in an automobile manufacturing enterprise in Guangzhou. Methods: From February 2020, a cluster sampling method was used to select 3486 male workers exposed to noise in an automobile manufacturing enterprise in Guangzhou in 2018. After screening, 2608 were selected as the research objects. Pure tone hearing threshold test, noise exposure level test and questionnaire survey were conducted, and the cumulative noise exposure was calculated. Chi square test and unconditional logistic regression were used to analyze the correlation between various factors and high frequency hearing loss. Results: The detection rate of high-frequency hearing loss in noise exposed workers was 34.20% (892/2608) , there were significant differences in the two groups among age, marital status, years of noise exposure, noise exposure equivalent A sound level, CNE, different working hours and exposure to electromagnetic radiation (P<0.05) . Multiple logistic regression analysis showed that age, CNE and exposure to electromagnetic radiation were independent risk factors for high-frequency hearing loss (P<0.05) , three shifts and two shifts were the protective factors for the occurrence of high-frequency hearing loss (OR=0.523, P<0.01) . Conclusion: Noise exposure is the main influencing factor of high-frequency hearing loss of noise-receiving workers in automobile manufacturing enterprises. Enterprises should strengthen noise control in the workplace, improve the working environment of electromagnetic radiation, and implement a scientific and healthy work shift system.

[Combined effect of noise and hand-transmitted vibration on noise-induced hearing loss in the automobile manufacturing industry].

Objective: To investigate the combined effect of noise and hand-transmitted vibration on noise-induced hearing loss (NIHL) in the automobile manufacturing industry. Methods: From September 2018 to January 2019, cluster sampling was used to select 998 workers in an automobile factory as study subjects, among whom 352 workers exposed to noise alone were enrolled as noise group, 342 workers exposed to noise and hand-transmitted vibration were enrolled as combined effect group, and 304 workers without exposure to occupational hazardous factors were enrolled as control group. A questionnaire survey and pure tone audiometry were performed for all study subjects. An analysis of variance was used for comparison of continuous data between groups, and the chi-square test was used for comparison of categorical data between groups; a ordinal polytomous logistic regression analysis was used to investigate the influencing factors for NIHL (with 0.05 as the inclusion criteria and 0.10 as the exclusion criteria for independent variables) . Results: There was a significant difference in L(Aeq, 8 h) between groups (P<0.05) ; the noise group and the combined effect group had a significantly higher L(Aeq, 8 h) than the control group (P<0.05) , while there was no significant difference in L(Aeq, 8 h) between the noise group and the combined effect group (P>0.05) . The control group had a significantly lower detection rate of hearing loss than the noise group and the combined effect group (P<0.0125) , and the combined effect group had a significantly higher detection rate of hearing loss than the noise group (P<0.0125) . The ordinal polytomous logistic regression analysis showed that after adjustment for confounding factors such as age, working years, sex, smoking, and drinking, both noise exposure and exposure to both noise and hand-transmitted vibration had an influence on workers' hearing (P<0.05) , and the workers exposed to both noise and hand-transmitted vibration had a higher risk of hearing loss than those exposed to noise alone. Conclusion: There may be a combined effect of noise and hand-transmitted vibration in the automobile manufacturing industry, which can increase the risk of NIHL in workers.

The nuclear hormone receptor E75A regulates vitellogenin gene (Al-Vg) expression in the mirid bug Apolygus lucorum.

Apolygus lucorum is the predominant pest of Bacillus thuringiensis (Bt) cotton in China. 20-hydroxyecdysone (20E) plays a key role in the reproduction of this insect. To better understand the mechanism underlying 20E-regulated reproduction, the nuclear hormone receptor E75 isoform-A of Ap. lucorum (Al-E75A) was cloned and its expression analysed. A 2241-bp sequence of Al-E75A cDNA encoded an open reading frame of a polypeptide with a predicted molecular mass of 69.04 kDa. Al-E75A mRNA was detected in female adult stages of Ap. lucorum with peak expression in 7-day-old animals. Al-E75A was also expressed in several tissues, particularly in the fat body and ovary. A 3.2 kb Al-E75A mRNA was detected in all tissues by Northern blot. The fecundity and longevity were significantly decreased in female adults treated with Al-E75A small interfering RNA. The rates of egg incubation rates were considerably lower in the RNA interference-treated animals compared to the untreated controls. In order to investigate the molecular mechanism underlying the effects described above, vitellogenin (Al-Vg) was selected for further investigation. The expression pattern of Al-Vg was similar to that of Al-E75A and was up-regulated by 20E. After knockdown of Al-E75A, the expression profile of Al-Vg and the protein levels were down-regulated. These findings suggest that Al-E75A plays a crucial role in the regulation of Al-Vg expression in Ap. lucorum.

[Prevalence of breast and gynecological diseases in female workers in the administrative office and workshop of an automobile part factory].

Objective: To investigate the prevalence of breast and gynecological diseases in female workers in the administrative office and workshop of an automobile part factory, and to provide a basis for promoting the health of female workers. Methods: In March 2015, color ultrasound examination of the breast, uterus, and bilateral adnexa was performed for all female workers, and routine gynecological examination, routine leucorrhea examination, and thinprep liquid-based cytology test were performed for married female workers. The detection rates of breast and gynecological diseases in female workers in the administrative office and workshop were analyzed. Results: In the 314 female workers, the overall detection rate of breast and gynecological diseases was 86.31%; the detection rate of abnormal breast ultrasound results was 72.93%, mainly breast hyperplasia; the detection rate of abnormal gynecological ultrasound results was 12.14%, mainly hysteromyoma, pelvic effusion, and uterus-rectum fossa effusion. The overall detection rate of cervicitis or vaginitis in married female workers was 66.86%. The univariate analysis showed that compared with those in the administrative office, the female workers in the workshop had significantly higher detection rates of breast hyperplasia and grade 2 breast lesions on the Breast Imaging-Reporting and Data System (BI-RADS) and significantly lower detection rates of hysteromyoma and grade 3 breast lesions on the BI-RADS (all P <0.05) . The multivariate analysis showed that age was a risk factor for hysteromyoma (OR=1.261) , age and working in the workshop were risk factors for breast hyperplasia (OR=1.065 and 1.834) , married status was a protective factor against breast hyperplasia and grade 2 breast lesions on the BI-RADS (OR=0.334 and 0.450) , and working in workshop was a risk factor for grade 2 breast lesions on the BI-RADS (OR=1.890) and a protective factor against grade 3 breast lesions on the BI-RADS (OR=0.355) . Conclusion: Female workers in an automobile part factory have high prevalence rates of breast and gynecological diseases. Night shifts for female workers in the workshop should be reduced as much as possible, and female workers, especially those in the administrative office, should be guided to release pressure and take a balanced diet.

Ecdysone receptor isoform-B mediates soluble trehalase expression to regulate growth and development in the mirid bug, Apolygus lucorum (Meyer-Dür).

Ecdysone receptor (EcR) is the hormonal receptor of ecdysteroids and strictly regulates growth and development in insects. However, the action mechanism of EcR is not very clear. In this study, the cDNA of EcR isoform-B was cloned from Apolygus lucorum (AlEcR-B) and its expression profile was investigated. We reduced AlEcR-B mRNA expression using systemic RNA interference in vivo, and obtained knockdown specimens. Examination of these specimens indicated that AlEcR-B is required for nymphal survival, and that reduced expression is associated with longer development time and lower nymphal weight. To investigate the underlying molecular mechanism of the observed suppression effects, we selected trehalase for a detailed study. Transcript encoding soluble trehalase (AlTre-1) was up-regulated by 20-hydroxyecdysone and in agreement with the mRNA expression of AlEcR-B. The expression profile of AlTre-1, soluble trehalase activity and translated protein level in the midgut of surviving nymphs were down-regulated, compared with controls, after the knockdown expression of AlEcR-B. By contrast, membrane-bound trehalase activity, the related gene expression and translated protein level remained at their initial levels. However, trehalose content significantly increased and the glucose content significantly decreased under the same conditions. We propose that AlEcR-B controls normal carbohydrate metabolism by mediating the expression of AlTre-1 to regulate the growth and development in A. lucorum, which provide an extended information into the functions of AlEcR-B.

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 (LHAASO) of the bright GRB 221009A, which serendipitously occurred within the instrument's 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 and then rose to a peak ~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 of ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

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.

The gas density measurement of one long distance supersonic molecular beam.

The gas density of the supersonic molecular beam (SMB) is a crucial parameter for the fueling or diagnostic process in the tokamak experiments. Using the microphone, one improved method of gas density measurement is proposed, which can greatly improve the measurement capacity by about 3 orders of magnitude by studying the pulsed signal characteristic of the microphone when it is pushed by the SMB. The gas density of the SMB is measured within the axial range of 20-2000 mm, and the axial central density at 2000 mm is about 100 times less than that at 20 mm. It is also found that the radial density distribution follows the Gaussian function in both free expansion (where the SMB can expand freely without any influence from the vacuum chamber) and restricted expansion (where the expansion of the SMB is restricted inside the flight tube of the vacuum system). And the axial central density decreases with the axial distance, which follows the inverse square law in the free expansion, but it deviates from this law in the restricted expansion.