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.
We study the evolution of the temporal properties of MAXI J1820+070 during the 2018 outburst in its hard state from MJD 58,190 to 58,289 with Insight-HXMT in a broad energy band 1-150 keV. We find ...different behaviors of the hardness ratio, the fractional rms and time lag before and after MJD 58,257, suggesting a transition occurred around this point. The observed time lags between the soft photons in the 1-5 keV band and the hard photons in higher energy bands, up to 150 keV, are frequency-dependent: the time lags in the low-frequency range, 2-10 mHz, are both soft and hard lags with a timescale of dozens of seconds but without a clear trend along the outburst; the time lags in the high-frequency range, 1-10 Hz, are only hard lags with a timescale of tens of milliseconds; they first increase until around MJD 58,257 and decrease after this date. The high-frequency time lags are significantly correlated to the photon index derived from the fit to the quasi-simultaneous NICER spectrum in the 1-10 keV band. This result is qualitatively consistent with a model in which the high-frequency time lags are produced by Comptonization in a jet.
Abstract
We select and characterize a sample of massive (log(
M
*
/
M
⊙
) > 10.6) quiescent galaxies (QGs) at 3 <
z
< 5 in the latest Cosmological Evolution Survey catalog (COSMOS2020). QGs are ...selected using a new rest-frame color-selection method, based on their probability of belonging to the quiescent group defined by a Gaussian mixture model (GMM) trained on rest-frame colors (
NUV
−
U
,
U
−
V
,
V
−
J
) of similarly massive galaxies at 2 <
z
< 3. We calculate the quiescent probability threshold above which a galaxy is classified as quiescent using simulated galaxies from the
shark
semi-analytical model. We find that, at
z
≥ 3 in
shark
, the GMM/
NUVU
−
VJ
method outperforms classical rest-frame
UVJ
selection and is a viable alternative. We select galaxies as quiescent based on their probability in COSMOS2020 at 3 <
z
< 5, and compare the selected sample to both
UVJ
- and
NUVrJ
-selected samples. We find that, although the new selection matches
UVJ
and
NUVrJ
in number, the overlap between color selections is only ∼50%–80%, implying that rest-frame color commonly used at lower-redshift selections cannot be equivalently used at
z
> 3. We compute median rest-frame spectral energy distributions for our sample and find the median QG at 3 <
z
< 5 has a strong Balmer/4000 Å break, and residual
NUV
flux indicating recent quenching. We find the number densities of the entire quiescent population (including post-starbursts) more than doubles from 3.5 ± 2.2 × 10
−6
Mpc
−3
at 4 <
z
< 5 to 1.4 ± 0.4 × 10
−5
Mpc
−3
at 3 <
z
< 4, confirming that the onset of massive galaxy quenching occurs as early as 3 <
z
< 5.
Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into ...a single compound has important scientific implications. Here we report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state then further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. The electrical resistivity measurement with V shape change signals the transition from a Rashba type topological trivial to a topological insulator phase at 2 GPa, which is caused by an energy gap close then reopen with band inverse. Superconducting transition appears at 8 GPa with a critical temperature T
of 5.3 K. Structure refinements indicate that the consecutive phase transitions are correlated to the changes in the Bi-Te bond and bond angle as function of pressures. The Hall Effect measurements reveal an intimate relationship between superconductivity and the unusual change in carrier density that points to possible unconventional superconductivity.
Elevated standardised mortality ratio of cardiovascular diseases (CVD) in patients with brain tumours may result from differences in the CVD incidences and cardiovascular risk factors. We compared ...the risk of CVD among patients with a primary malignant or non-malignant brain tumour to a matched general population cohort, accounting for other co-morbidities.
Using data from the Secured Anonymised Information Linkage (SAIL) Databank in Wales (United Kingdom), we identified all adults aged ≥ 18 years in the primary care database with first diagnosis of malignant or non-malignant brain tumour identified in the cancer registry in 2000-2014 and a matched cohort (case-to-control ratio 1:5) by age, sex and primary care provider from the general population without any cancer diagnosis. Outcomes included fatal and non-fatal major vascular events (stroke, ischaemic heart disease, aortic and peripheral vascular diseases) and venous thromboembolism (VTE). We used multivariable Cox models adjusted for clinical risk factors to compare risks, stratified by tumour behaviour (malignant or non-malignant) and follow-up period.
There were 2869 and 3931 people diagnosed with malignant or non-malignant brain tumours, respectively, between 2000 and 2014 in Wales. They were matched to 33,785 controls. Within the first year of tumour diagnosis, malignant tumour was associated with a higher risk of VTE (hazard ratio HR 21.58, 95% confidence interval 16.12-28.88) and stroke (HR 3.32, 2.44-4.53). After the first year, the risks of VTE (HR 2.20, 1.52-3.18) and stroke (HR 1.45, 1.00-2.10) remained higher than controls. Patients with non-malignant tumours had higher risks of VTE (HR 3.72, 2.73-5.06), stroke (HR 4.06, 3.35-4.93) and aortic and peripheral arterial disease (HR 2.09, 1.26-3.48) within the first year of diagnosis compared with their controls.
The elevated CVD and VTE risks suggested risk reduction may be a strategy to improve life quality and survival in people with a brain tumour.
PREMISE OF THE STUDY: Land-plant plastid genomes have only rarely undergone significant changes in gene content and order. Thus, discovery of additional examples adds power to tests for causes of ...such genome-scale structural changes. METHODS: Using next-generation sequence data, we assembled the plastid genome of saguaro cactus and probed the nuclear genome for transferred plastid genes and functionally related nuclear genes. We combined these results with available data across Cactaceae and seed plants more broadly to infer the history of gene loss and to assess the strength of phylogenetic association between gene loss and loss of the inverted repeat (IR). KEY RESULTS: The saguaro plastid genome is the smallest known for an obligately photosynthetic angiosperm (~113 kb), having lost the IR and plastid ndh genes. This loss supports a statistically strong association across seed plants between the loss of ndh genes and the loss of the IR. Many nonplastid copies of plastid ndh genes were found in the nuclear genome, but none had intact reading frames; nor did three related nuclear-encoded subunits. However, nuclear pgr5, which functions in a partially redundant pathway, was intact. CONCLUSIONS: The existence of an alternative pathway redundant with the function of the plastid NADH dehydrogenase-like complex (NDH) compex may permit loss of the plastid ndh gene suite in photoautotrophs like saguaro. Loss of these genes may be a recurring mechanism for overall plastid genome size reduction, especially in combination with loss of the IR.
In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT) Satellite, which was launched on 2017 June 15. The new pulsar ...navigation method "Significance Enhancement of Pulse-profile with Orbit-dynamics" is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from 2017 August 31 to September 5. Using the five-day long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard: High Energy X-ray Telescope, Medium Energy X-ray Telescope, and Low Energy X-ray Telescope, respectively. By combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3 ) and 10 m s−1 (3 ), respectively.
This paper studies the cumulative effect of various parameters, namely anionic polyacrylamide (APAM) concentration, oil concentration, pH, trans-membrane pressure (TMP), and total dissolved solid ...(TDS), and obtains optimal parameters for the minimum relative flux (J/J₀) declining in aqueous solutions with response surface methodology (RSM). In order to analyze the mutual interaction and optimal values of parameters affecting ultrafiltration, a central composite rotatable design (CCRD), one method of RSM, was employed. The analysis of variance (ANOVA) of the cubic polynomial model demonstrated that this model was highly significant and reliable. The results show that the effect of APAM and oil on J/J₀ has an inverse trend with pH value increasing. Moreover, the mutual interaction of initial APAM (oil) concentration (CAPAM₍ₒᵢₗ₎) and pH (TMP) were negligible, while the mutual interaction of CAPAM and Cₒᵢₗ has an obvious effect, i.e. the effect of initial feed CAPAM became more important at higher values of initial feed Cₒᵢₗ, and the J/J₀ was only about 4%. The favorable operate conditions in this ultrafiltration process were at low CAPAM, Cₒᵢₗ, pH, and TMP, which agreed with the conclusions of many authors, while considering water production, CAPAM and Cₒᵢₗ<50mg/L, pH<4, and TMP<0.075MPa could be accepted.
Abstract
DNA damage and repair are linked to cancer. DNA damage that is induced endogenously or from exogenous sources has the potential to result in mutations and genomic instability if not properly ...repaired, eventually leading to cancer. Inflammation is also linked to cancer. Reactive oxygen and nitrogen species (RONs) produced by inflammatory cells at sites of infection can induce DNA damage. RONs can also amplify inflammatory responses, leading to increased DNA damage. Here, we focus on the links between DNA damage, repair, and inflammation, as they relate to cancer. We examine the interplay between chronic inflammation, DNA damage and repair and review recent findings in this rapidly emerging field, including the links between DNA damage and the innate immune system, and the roles of inflammation in altering the microbiome, which subsequently leads to the induction of DNA damage in the colon. Mouse models of defective DNA repair and inflammatory control are extensively reviewed, including treatment of mouse models with pathogens, which leads to DNA damage. The roles of microRNAs in regulating inflammation and DNA repair are discussed. Importantly, DNA repair and inflammation are linked in many important ways, and in some cases balance each other to maintain homeostasis. The failure to repair DNA damage or to control inflammatory responses has the potential to lead to cancer.
We report observations of stimulated electromagnetic emission (SEE) induced by high power high frequency (HF) radio waves near the third electron gyroharmonic (3fce ${f}_{\mathrm{ce}}$) at European ...Incoherent Scatter Radar (EISCAT). It is discovered that stimulated Brillouin scattering (SBS) spectrum behaves similarly as spectral ion lines of the incoherent scatter radar (ISR) for HF pumping frequency above 3fce ${f}_{\mathrm{ce}}$. The SBS spectral width shows correlation with electron to ion temperature ratio Te/Ti. A new inversion method is proposed by incorporating the SBS spectral width within an artificial neural network approach to achieve electron temperature inversion for ionospheric turbulent plasmas. This work provides a potential new technique to diagnose parameters in the modified ionosphere when the ISR is not available.
Plain Language Summary
Nonlinear interaction of high‐power electromagnetic waves and magnetized plasmas produces a plethora of fundamental phenomena. Stimulated electromagnetic emissions (SEEs) arises from nonlinear interaction and induces plasma turbulence observable by incoherent scatter radars (ISR). It is important to compare SEE and ISR spectral lines for understanding nonlinear physics in the resonance regime. The SEE‐based methods may provide complimentary diagnostic tools to the traditional ISR theory. In addition, the SEE‐based inversion theory and method is still lacking due to nonlinear wave‐wave and wave‐particle interaction. The physical correlation between SEEs and ISR spectra will provide benefit for better inversion techniques. This work reports experimental observation and parameter inversion of stimulated Brillouin scatter (SBS) at EISCAT (European Incoherent Scatter Radar). We successfully discover similarity between the ISR ion lines and SBS near the third electron gyroharmonic by high power radio waves at EISCAT. A new diagnostic technique based on SEEs have been developed using physical model and an artificial neural network approach. The inversion of SEEs overcomes the non‐Maxwellian limitations on ISR measurements. These observations demonstrate a physical intrinsic correlation between ISR ion and SBS lines, which provides possibilities for developing new inversion techniques based on SBS in comparison with well‐known ISR theory.
Key Points
Discovery of similarity between high frequency‐induced stimulated Brillouin scattering (SBS) and incoherent scatter radar spectrum
Intelligent stimulated electromagnetic emission inversion architecture proposed by incorporating physical insights within an artificial neural network approach
Novel ionospheric electron temperature inversion based on SBS and downshifted maximum spectral lines
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