The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10
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 rays
. 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.
). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane
, 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.
Members of the genus Aeromonas are opportunistic pathogen of a variety of aquatic animals that exhibits multidrug resistance, phenotypes, virulence genes and virulence. The present study described ...the species distribution and the potential pathogenicity of Aeromonas isolated from healthy Northern snakehead (Channa argus) in China. Molecular identification revealed that A. veronii biovar veronii (69/167; 41·3%) and A. hydrophila (41/167; 24·6%) were the most common species found in Northern snakehead intestine based on sequencing of the 16S rRNA gene and DNA gyrase subunit B protein. The distribution of seven virulence factors including aer (84·4%), act (80·8%), ser (40·1%), Aha (27·5%), lip (23·4%), exu (15·0%) and LuxS (12·6%) were determined exclusively in Aeromonas isolates. All the seven virulence genes were present in 9·6% (16/167), among which 11 strains were identified as A. veronii biovar veronii. For the strains harbouring seven virulence genes, the 50% lethal doses (LD50) of isolates were lower compared to the isolates carrying two virulence genes. The challenge tests revealed that isolate W31 had the lowest lethal dose, causing 50% mortality at 4·5 × 103 colony‐forming units (CFU) per ml. Furthermore, histopathology of Northern snakehead infected with Aeromonas strains showed necrosis and congestion in liver, spleen and kidney and also damage to the intestine. This study confirms that the Aeromonas strains isolated from healthy Northern snakehead may be a cause of concern for public health.
Significance and Impact of the Study
Aeromonas species are widely distributed in aquatic environments and have considerable virulence potential. The aim of this study was to identify Aeromonas strains isolated from healthy Northern snakehead, and to investigate if Aeromonas species isolated from healthy fish potential pathogenicity with special reference to virulence and epidemiology studies.
Significance and Impact of the Study: Aeromonas species are widely distributed in aquatic environments and have considerable virulence potential. The aim of this study was to identify Aeromonas strains isolated from healthy Northern snakehead, and to investigate if Aeromonas species isolated from healthy fish potential pathogenicity with special reference to virulence and epidemiology studies.
Double neutron star (DNS) merger events are promising candidates of short gamma-ray burst (sGRB) progenitors as well as high-frequency gravitational wave (GW) emitters. On August 17, 2017, such a ...coinciding event was detected by both the LIGO-Virgo gravitational wave detector network as GW170817 and Gamma-Ray Monitor on board NASA's Fermi Space Telescope as GRB 170817A. Here, we show that the fluence and spectral peak energy of this sGRB fall into the lower portion of the distributions of known sGRBs. Its peak isotropic luminosity is abnormally low. The estimated event rate density above this luminosity is at least Formula: see text Gpc
yr
, which is close to but still below the DNS merger event rate density. This event likely originates from a structured jet viewed from a large viewing angle. There are similar faint soft GRBs in the Fermi archival data, a small fraction of which might belong to this new population of nearby, low-luminosity sGRBs.
We report a study of the processes of e^{+}e^{-}→K^{+}D_{s}^{-}D^{*0} and K^{+}D_{s}^{*-}D^{0} based on e^{+}e^{-} annihilation samples collected with the BESIII detector operating at BEPCII at five ...center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb^{-1}. An excess of events over the known contributions of the conventional charmed mesons is observed near the D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0} mass thresholds in the K^{+} recoil-mass spectrum for events collected at sqrts=4.681 GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as (3982.5_{-2.6}^{+1.8}±2.1) MeV/c^{2} and (12.8_{-4.4}^{+5.3}±3.0) MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 σ over the contributions only from the conventional charmed mesons. This is the first candidate for a charged hidden-charm tetraquark with strangeness, decaying into D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0}. However, the properties of the excess need further exploration with more statistics.
We present X-ray timing results of the new black hole candidate MAXI J1535−571 during its 2017 outburst from Hard X-ray Modulation Telescope (Insight-HXMT) observations taken from 2017 September 6 to ...23. Following the definitions given by Belloni, we find that the source exhibits transitions from the low/hard state to the hard intermediate state, and eventually to the soft intermediate state. Quasi-periodic oscillations (QPOs) are found in the intermediate states, which suggest different types of QPOs. With the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of the QPO amplitude and centroid frequency up to 100 keV, which has rarely been explored by previous satellites. We also find that the phase lag at the type-C QPOs centroid frequency is negative (soft lag) and strongly correlated with the centroid frequency. Assuming a geometrical origin of type-C QPOs, the source is consistent with being a high-inclination system.
The cross section for the process e^{+}e^{-}→π^{+}π^{-}J/ψ is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb^{-1} of data collected with the BESIII detector operating ...at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (4222.0±3.1±1.4) MeV/c^{2} and a width of (44.1±4.3±2.0) MeV, while the second one has a mass of (4320.0±10.4±7.0) MeV/c^{2} and a width of (101.4_{-19.7}^{+25.3}±10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in e^{+}e^{-}→π^{+}π^{-}J/ψ for the first time. The statistical significance of this resonance is estimated to be larger than 7.6σ. The mass and width of the second resonance agree with the Y(4360) resonance reported by the BABAR and Belle experiments within errors. Finally, the Y(4008) resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.
The impact of central Asian aridification on the low latitude North Pacific Ocean since the late Miocene remains unclear. To address this question, we systematically studied an abyssal manganese ...nodule from the northwestern Pacific Ocean, which is expected to be sensitive to eolian dust sourced from central Asia. Geochemical variations and the fossilized remains of magnetotactic bacteria within the studied nodule manifest two prominent Asian aridification events at ∼8–7 Ma and 3.6–0 Ma. These results suggest that central Asian aridification impacted both primary productivity and abyssal microbial activity in the NW Pacific Ocean via eolian dust inputs. In contrast to the Pliocene aridification event, the late Miocene event was associated with a primary productivity bloom that is not evident in coeval global primary productivity records, which indicates that the ∼8–7 Asian aridification event was likely due to NE Tibetan Plateau uplift rather than to global cooling.
Plain Language Summary
Central Asian aridification since the late Miocene has had a significant influence on climate, temperature, and North Pacific Ocean productivity through eolian dust inputs transported by westerlies. However, it is unclear whether the low latitude of NW Pacific Ocean responded to this aridification. We systematically analyzed the geochemistry and magnetism of a NW Pacific manganese nodule, and find that Asian aridification since, the late Miocene impacted biogeochemical cycling and abyssal microbial activity in the NW Pacific Ocean via eolian dust input. Our results imply that these two prominent Asian aridification events at around 8–7 Ma and ca. 3.6 Ma can be attributed to the NE Tibetan Plateau uplift and global cooling, respectively.
Key Points
A manganese nodule from the NW Pacific carries a paleoclimatic record of Asian aridification since the Late Miocene
Asian aridification impacted biogeochemical cycling and abyssal microbial activity in the NW Pacific Ocean
Major Asian aridification events at ∼8–7 Ma and ∼3.6–0 Ma may be attributed to NE Tibetan Plateau uplift and global cooling, respectively
Background
Enucleation of pancreatic neuroendocrine tumours (pNETs) via robotic surgery has rarely been described. This study sought to assess the safety and efficiency of robotic surgery for the ...enucleation of small pNETs.
Methods
A comparison was conducted of enucleation of pNETs smaller than 2 cm by robotic or open surgery between January 2000 and May 2015. Propensity score matching was used to balance sex, age, BMI, tumour location and tumour diameter. Pathological results, safety‐related outcomes (postoperative pancreatic fistula (POPF) rate, estimated blood loss, and short‐term mortality and morbidity) and efficiency‐related outcomes (duration of surgery and postoperative length of hospital stay) were compared between the groups.
Results
A cohort of 120 patients with pNET were enrolled in the study (1 : 1 matched for open or robotic surgery, 60 per group). Ninety‐three patients (77·5 per cent) had a grade 1 tumour and 114 (95·0 per cent) had an insulinoma. Robotic surgery had a conversion rate of 5 per cent (3 of 60), and was not associated with an increased POPF rate (10 per cent versus 17 per cent after open surgery; P = 0·283) or grade III–V surgical complications according to the Dindo–Clavien classification (3 versus 10 per cent respectively; P = 0·272). Estimated blood loss was reduced with the robotic approach (32·5 versus 80·0 ml in the open group; P = 0·008), as was duration of surgery (117 versus 150 min; P < 0·001). Length of hospital stay after surgery was similar in the two groups (12·0 versus 13·5 days respectively; P = 0·071).
Conclusion
Robotic surgery for enucleation of pNETs smaller than 2 cm did not increase POPF or major complication rates, and reduced the duration of surgery and estimated blood loss, compared with open surgery. Registration number: NCT02125929 (
https://www.clinicaltrials.gov/).
Robot beats surgeon
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