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1.
Phys Rev Lett ; 126(24): 241103, 2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34213924

RESUMO

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.

2.
Science ; 373(6553): 425-430, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34261813

RESUMO

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.

3.
Phys Rev Lett ; 127(3): 031102, 2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34328784

RESUMO

We report observations of gamma-ray emissions with energies in the 100-TeV energy region from the Cygnus region in our Galaxy. Two sources are significantly detected in the directions of the Cygnus OB1 and OB2 associations. Based on their positional coincidences, we associate one with a pulsar PSR J2032+4127 and the other mainly with a pulsar wind nebula PWN G75.2+0.1, with the pulsar moving away from its original birthplace situated around the centroid of the observed gamma-ray emission. This work would stimulate further studies of particle acceleration mechanisms at these gamma-ray sources.

4.
Nature ; 594(7861): 33-36, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34002091

RESUMO

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.

5.
Phys Rev Lett ; 126(14): 141101, 2021 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-33891464

RESUMO

We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of π^{0}'s produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk.

6.
Eur Rev Med Pharmacol Sci ; 23(21): 9180-9188, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31773668

RESUMO

OBJECTIVE: The objective of this paper is to determine whether SIRT3 could retard intervertebral disc degeneration and study the mechanism. MATERIALS AND METHODS: We chose the 3-month mice to establish intervertebral disc degeneration model and study the effect of SIRT3 on the intervertebral disc by Western blotting, quantitative Real Time-Polymerase Chain Reaction (qRT-PCR), immunohistochemistry. Mouse nucleus pulposus cells were cultured to study the exact mechanism. RESULTS: The expression of SIRT3 was decreased in degenerated human nucleus pulposus. Intervertebral discs of mice treated with theacrine expressed more collagen II and less collagen X. In addition, nucleus pulposus cells stimulated with interleukin-1ß (IL-1ß) expressed less SIRT3 than that in the control group and nucleus pulposus cells with SIRT3 overexpress vectors expressed more collagen II FOXO3a and superoxide dismutase 2 (SOD2), indicating that SIRT3 could improve the intervertebral disc degeneration by anti-oxidative stress. CONCLUSIONS: SIRT3 is a protective factor for intervertebral discs and can reduce oxidative stress in the intervertebral disc.


Assuntos
Proteína Forkhead Box O3/biossíntese , Degeneração do Disco Intervertebral/fisiopatologia , Sirtuína 3/fisiologia , Superóxido Dismutase/biossíntese , Animais , Colágeno/biossíntese , Colágeno Tipo II/biossíntese , Humanos , Interleucina-1beta/farmacologia , Disco Intervertebral , Degeneração do Disco Intervertebral/metabolismo , Camundongos , Núcleo Pulposo , Estresse Oxidativo/fisiologia , Fatores de Proteção , Transdução de Sinais/fisiologia , Sirtuína 3/biossíntese
7.
Phys Rev Lett ; 123(5): 051101, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31491288

RESUMO

We report on the highest energy photons from the Crab Nebula observed by the Tibet air shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon number measured in an air shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.

8.
Zhonghua Yi Xue Za Zhi ; 98(34): 2749-2753, 2018 Sep 11.
Artigo em Chinês | MEDLINE | ID: mdl-30220173

RESUMO

Objective: To investigate the effect and mechanism of microRNA-146a (miR-146a) on Toll-Like Receptor 4 (TLR4) inflammatory signal pathway in the lung tissues of rats with mechanical ventilator-induced lung injury. Methods: Thirty-two healthy male Sprague-Dawley rats were randomly divided into 4 groups (n=8 each): group A, normal control group, no mechanical ventilation, spontaneous breathing; group B, mechanical ventilation injury; group C, mechanical ventilation injury plus no-load virus transfection; group D, mechanical ventilation injury plus virus transfection; in group B, C, and D, mechanical ventilation were performed, respiratory rate was controlled at 80 beats/min, tidal volume was 40 ml/kg, inhaled oxygen concentration (FiO2) was 21%, inhalation/expiration ratio was 1∶2, positive end expiratory pressure ventilation (PEEP) was 0, each group were ventilated 4 hours daily, 7 days continuously to establish ventilator induced lung injury (VILI) rat model. Paraffin-embedded sections of lung tissue were stained with HE, the morphology and damage of lung tissue were observed under microscope. The lungs wet and dry ratio (W/D), the levels of inflammatory cytokines interleukin (IL)-1ß, IL-2 and tumor necrosis factor (TNF)-α were determined. Real-time PCR was used to detect the expression of TLR4 mRNA. The level of TLR4 protein was determined by Western blot. Results: The levels of lung tissue W/D and lung injury scores in group B (6.41±0.10, 11.38±0.92), group C (6.45±0.19, 11.75±1.04), group D (5.95±0.14, 7.53±4.78) were significantly increased than those in group A (4.33±0.08, 0.25±0.46), and in group D they were significantly decreased than group C (all P<0.01). The levels of IL-1ß, IL-2, TNF-α in group B[(36.07±4.28) pg/ml, (5.02±0.63) ng/ml, (382.57±35.41) ng/ml], group C[(35.82±5.47) pg/ml, (4.98±0.71) ng/ml, (375.13±36.95) ng/ml], group D[(27.01±3.18) pg/ml, (3.96±0.82) ng/ml, (297.56±39.08) ng/ml]were significantly increased than those in group A[(21.46±3.15) pg/ml, (2.45±0.17) ng/ml, (195.92±18.07) ng/ml], and in group D they were significantly decreased than group C (all P<0.01). The relative expression levels of TLR4 mRNA and TLR4 proteins in group B (29.57±5.10, 0.75±0.110), group C (27.27±4.72, 0.77±0.130), group D (12.89±2.58, 0.48±0.057) were significantly increased than those in group A (1.02±0.13, 0.18±0.025), and in group D they were significantly decreased than group C (all P<0.01). There was no significant difference of all the above indicators between group B and C (all P>0.05). Conclusions: MiR-146a can reduce acute lung inflammation and TLR4 expression in lungs of rats with mechanical ventilator-induced lung injury. MiR-146a may inhibit the inflammatory response through TLR4 signaling pathway.


Assuntos
Lesão Pulmonar Induzida por Ventilação Mecânica , Animais , Líquido da Lavagem Broncoalveolar , Pulmão , Masculino , MicroRNAs , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Receptor 4 Toll-Like
9.
Zhonghua Jie He He Hu Xi Za Zhi ; 41(2): 100-104, 2018 Feb 12.
Artigo em Chinês | MEDLINE | ID: mdl-29429215

RESUMO

Objective: To improve the understanding of chronic pulmonary aspergillosis (CPA) by analyzing the clinical manifestations, imaging and pathological features, diagnosis, treatment and prognosis of this disease. Methods: Cases of CPA, proven by microbiological evidence based on pathological study in Fuzhou General Hospital of the People's Liberation Army and Affiliated Fuzhou City First Hospital of Fijian Medical University from January 2006 to October 2016 were retrospectively analyzed. Results: The patients consisted of 17 males and 12 females, aged 24 to 75 years, mean (42±16) years. The underlying disorders included post-tuberculosis infection (n=11), bronchiectasis (n=8), chronic obstructive pulmonary disease (n=3) and diabetes mellitus (n=2). The main clinical symptoms included productive cough (n=25), chronic sputum production (n=18) and hemoptysis (n=15). Serum GM antigen tests were performed in 19 cases, and the result was positive in 12 patients. BALF GM antigen tests were performed in 2 cases, both of which were positive. Chest CT showed that the lesions were located predominantly in the upper lobes (n=24). Single cavity with interior irregular intraluminal material (n=16) and multiple cavities with interior irregular intraluminal material (n=10) were the most frequent CT findings, while the "air crescent sign" was found in 13 cases. In the 22 patients who underwent surgical treatment, Aspergillus filaments were found in the cavity (n=20) or the bronchi (n=2) of lung samples, and histological examination didn't show tissue invasion by fungi. Surgical therapy was performed in 22 patients, with complete remission in 19 cases, and death in 3 cases. Anti-fungal therapy was administered in 6 patients, with partial remission in 4, and stable disease in 2 cases. One patient was not treated. Conclusions: CPA is more frequently seen in patients with underlying chronic pulmonary diseases. The common CT findings are single or multiple cavities with interior irregular intraluminal materials. Aspergillus filament in the cavity or bronchi of lung samples, without parenchymal invasion, is the proof of CPA. The surgical cure rate for simple aspergilloma and aspergillus nodule is high, while the risk of operation for chronic cavitary disease is high. GM antigen test may be an evidence for diagnosing CPA.


Assuntos
Aspergillus/isolamento & purificação , Hemoptise , Aspergilose Pulmonar/diagnóstico , Adulto , Idoso , China , Feminino , Humanos , Pulmão , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
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