Background and purpose
Previous studies suggested that the overall burden of prior infections contributes to cardiovascular diseases and stroke. In the present study, the association between ...infectious burden (IB) and Alzheimer's disease (AD) was examined.
Methods
Antibody titers to common infectious pathogens including cytomegalovirus (CMV), herpes simplex virus type 1 (HSV‐1), Borrelia burgdorferi, Chlamydophila pneumoniae and Helicobacter pylori were measured by enzyme‐linked immunosorbent assay in 128 AD patients and 135 healthy controls. IB was defined as a composite serological measure of exposure to these common pathogens.
Results
Seropositivities toward zero−two, three and four−five of these pathogens were found in 44%, 40% and 16% of healthy controls but in 20%, 44% and 36% of AD patients, respectively. IB, bacterial burden and viral burden were independently associated with AD after adjusting for age, gender, education, APOE genotype and various comorbidities. Mini‐Mental State Examination scores were negatively correlated with IB in all cases. Serum beta‐amyloid protein (Aβ) levels (i.e. Aβ40, Aβ42 and total Aβ) and inflammatory cytokines (i.e. interferon‐γ, tumor necrosis factor α, interleukin‐1β and interleukin‐6) in individuals exposed to four−five infectious pathogens were significantly higher than those exposed to zero−two or three pathogens.
Conclusions
IB consisting of CMV, HSV‐1, B. burgdorferi, C. pneumoniae and H. pylori is associated with AD. This study supports the role of infection/inflammation in the etiopathogenesis of AD.
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Abstract
We report on analysis of observations of the bright transient X-ray pulsar Swift J0243.6+6124 obtained during its 2017-2018 giant outburst with Insight-HXMT, NuSTAR, and Swift observatories. ...We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields.
High-energy photons from the Crab Nebula
The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location ...makes the nebula the brightest gamma-ray source in the sky. The LHAASO Collaboration report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering.
Science
, abg5137, this issue p.
425
Detection of the Crab Nebula at peta–electron volt energies constrains the gamma-ray emission mechanism.
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 × 10
36
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 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.
Summary
Background
Serrated polyps of the colorectum have distinct histological features and malignant potential.
Aim
To assess the association between the presence of serrated polyps and synchronous ...advanced colorectal neoplasia.
Methods
Among 4989 asymptomatic Chinese individuals aged 50–70 years who underwent screening colonoscopy, 281 cases with advanced neoplasia (adenoma ≥1 cm, with tubulovillous/villous histology, with high‐grade dysplasia, or invasive adenocarcinoma) were compared with 4708 controls without advanced neoplasia for age, sex, smoking history, body mass index, family history of colorectal cancer and the presence of serrated polyps. Independent predictors of advanced neoplasia were determined by multivariate logistic regression analysis.
Results
The prevalence of advanced neoplasia and serrated polyps (excluding small distal hyperplastic polyps) was 5.7% and 5.6%, respectively. 3.7% and 0.4% subjects had proximal and large (≥10 mm) serrated polyps, respectively. Independent predictors of synchronous advanced colorectal neoplasia were the presence of sessile serrated adenomas (OR: 4.52; 95% CI: 2.40–8.49), proximal serrated polyps (OR: 2.23, 95% CI: 1.38–3.60), large serrated polyps (OR: 59.25; 95% CI: 18.85–186.21), hyperplastic polyps (OR: 1.66; 95% CI: 1.03–2.67), three or more serrated polyps (OR: 4.86; 95% CI: 1.24–19.15) and one or more non‐advanced tubular adenomas (OR: 3.58, 95% CI: 2.59–4.96).
Conclusion
Detection of proximal, sessile and/or large serrated polyps at screening colonoscopy is independently associated with an increased risk for synchronous advanced neoplasia.
High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of ...phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a 'smoothly broken power-law' model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.
Context.
No robust detection of prompt electromagnetic counterparts to fast radio bursts (FRBs) has yet been obtained, in spite of several multi-wavelength searches having been carried out so far. ...Specifically, X/
γ
-rays counterparts are predicted by some models.
Aims.
We aim to search for prompt
γ
-ray counterparts in the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) data, taking advantage of the unique combination of the large effective area in the keV–MeV energy range, and of sub-ms time resolution.
Methods.
We selected 39 FRBs that were promptly visible from the High-Energy (HE) instrument aboard Insight-HXMT. After calculating the expected arrival times at the location of the spacecraft, we searched for a significant excess in both individual and cumulative time profiles over a wide range of time resolutions, from several seconds down to sub-ms scales. Using the dispersion measures in excess of the Galactic terms, we estimated the upper limits on the redshifts.
Results.
No convincing signal was found, and for each FRB we constrained the
γ
-ray isotropic-equivalent luminosity and the released energy as a function of emission timescale. For the nearest FRB source, the periodic repeater FRB 180916.J0158+65, we find
L
γ
, iso
< 5.5 × 10
47
erg s
−1
over 1 s, whereas
L
γ
, iso
< 10
49
− 10
51
erg s
−1
for the bulk of FRBs. The same values scale up by a factor of ∼100 for a ms-long emission.
Conclusions.
Even on a timescale comparable with that of the radio pulse itself, no keV–MeV emission is observed. A systematic association with either long or short GRBs is ruled out with high confidence, except for sub-luminous events, as is the case for the core-collapse of massive stars (long) or binary neutron star mergers (short) viewed off axis. Only giant flares from extragalactic magnetars at least ten times more energetic than Galactic siblings are ruled out for the nearest FRB.
The Tibetan Plateau is the highest and one of the most demanding environments ever inhabited by humans. We investigated the timing and mechanisms of its initial colonization at the Nwya Devu site, ...located nearly 4600 meters above sea level. This site, dating from 40,000 to 30,000 years ago, is the highest Paleolithic archaeological site yet identified globally. Nwya Devu has yielded an abundant blade tool assemblage, indicating hitherto-unknown capacities for the survival of modern humans who camped in this environment. This site deepens the history of the peopling of the "roof of the world" and the antiquity of human high-altitude occupations more generally.
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