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.
A
bstract
By analyzing
e
+
e
−
annihilation data corresponding to an integrated luminosity of 2
.
93 fb
−
1
collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we report the ...first observations of the doubly Cabibbo-suppressed decays
D
+
→ K
+
π
0
π
0
and
D
+
→ K
+
π
0
η
. The branching fractions of
D
+
→ K
+
π
0
π
0
and
D
+
→ K
+
π
0
η
are measured to be (2
.
1 ± 0
.
4
stat
± 0
.
1
syst
) × 10
−
4
and (2
.
1 ± 0
.
5
stat
± 0
.
1
syst
) × 10
−
4
with statistical significances of 8.8
σ
and 5.5
σ
, respectively. In addition, we search for the subprocesses
D
+
→ K
*
(892)
+
π
0
and
D
+
→ K
*
(892)
+
η
with
K
*
(892)
+
→ K
+
π
0
. The branching fraction of
D
+
→ K
*
(892)
+
η
is determined to be (
4.4
−
1.5
stat
+
1.8
±
0
.
2
syst
)
×
10
−
4
, with a statistical significance of 3.2
σ
. No significant signal for
D
+
→ K
*
(892)
+
π
0
is found and we set an upper limit on the branching fraction of this decay at the 90% confidence level to be 5
.
4
×
10
−
4
.
Context.
A link has finally been established between magnetars and fast radio burst (FRB) sources. Within this context, a major issue that remains unresolved pertains to whether sources of ...extragalactic FRBs exhibit X/
γ
-ray outbursts and whether this is correlated with radio activity. If so, the subsequent goal is to identify these sources.
Aims.
We aim to constrain possible X/
γ
-ray burst activity from one of the nearest extragalactic FRB sources currently known. This is to be done over a broad energy range by looking for bursts over a range of timescales and energies that are compatible with those of powerful flares from extragalactic magnetars.
Methods.
We followed up on the observation of the as-yet nearest extragalactic FRB source, located at a mere 149 Mpc distance, namely, the periodic repeater
FRB 180916.J0158+65
. This took place during the active phase between 4 and 7 February 2020, using the Insight–Hard X-ray Modulation Telescope (Insight–HXMT). By taking advantage of the combination of broad-band wavelengths, a large effective area, and several independent detectors at our disposal, we searched for bursts over a set of timescales from 1 ms to 1.024 s with a sensitive algorithm that had been previously characterised and optimised. Moreover, through simulations, we studied the sensitivity of our technique in the released energy-duration phase space for a set of synthetic flares and assuming a range of different energy spectra.
Results.
We constrain the possible occurrence of flares in the 1−100 keV energy band to
E
< 10
46
erg for durations Δ
t
< 0.1 s over several tens of ks exposure.
Conclusions.
We can rule out the occurrence of giant flares similar to the ones that were observed in the few cases of Galactic magnetars. The absence of reported radio activity during our observations prevents us from making any determinations regarding the possibility of simultaneous high-energy emission.
Search for the decay hc→ π0J/ψ Ban, Y.; Boyko, I.; Cai, X. ...
The journal of high energy physics,
05/2022, Letnik:
2022, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
A search for the decay
h
c
→ π
0
J/ψ
is performed using a sample of
hc
produced in the reaction
e
+
e
−
→ π
+
π
−
h
c
. The data samples were collected with the BESIII detector at ...center-of-mass energies between 4.189 and 4.437 GeV, corresponding to a total integrated luminosity of 11 fb
−
1
. No significant signal is observed. Upper limits on the branching ratio
B
(
h
c
→ π
0
J/ψ
)
/
B
(
h
c
→ γη
c
→ γK
+
K
−
π
0
) and on the branching fraction
B
(
h
c
→ π
0
J/ψ
) are determined to be 7
.
5
×
10
−
2
and 4
.
7
×
10
−
4
at 90% confidence level, respectively. The latter is derived from the former using the measured branching fraction of the normalization channel. This is the first determination of the upper limit of the decay
h
c
→ π
0
J/ψ
.
ABSTRACT
We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER, and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray ...spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square amplitude were positively correlated. The QPO amplitude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that ‘failed’ (hard state only) and ‘successful’ outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes.
The Curiosity rover investigated a topographic structure known as Vera Rubin ridge, associated with a hematite signature in orbital spectra. There, Curiosity encountered mudstones interpreted as ...lacustrine deposits, conformably overlying the 300 m‐thick underlying sedimentary rocks of the Murray formation at the base of Mount Sharp. While the presence of hematite (α‐Fe2O3) was confirmed in situ by both Mastcam and ChemCam spectral observations and by the CheMin instrument, neither ChemCam nor APXS observed any significant increase in FeOT (total iron oxide) abundances compared to the rest of the Murray formation. Instead, Curiosity discovered dark‐toned diagenetic features displaying anomalously high FeOT abundances, commonly observed in association with light‐toned Ca‐sulfate veins but also as crystal pseudomorphs in the host rock. These iron‐rich diagenetic features are predominantly observed in “gray” outcrops on the upper part of the ridge, which lack the telltale ferric signature of other Vera Rubin ridge outcrops. Their composition is consistent with anhydrous Fe‐oxide, as the enrichment in iron is not associated with enrichment in any other elements, nor with detections of volatiles. The lack of ferric absorption features in the ChemCam reflectance spectra and the hexagonal crystalline structure associated with dark‐toned crystals points toward coarse “gray” hematite. In addition, the host rock adjacent to these features appears bleached and shows low‐FeOT content as well as depletion in Mn, indicating mobilization of these redox‐sensitive elements during diagenesis. Thus, groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on Vera Rubin ridge.
Plain Language Summary
The NASA rover Curiosity investigated Vera Rubin ridge, a specific landform within the Gale crater on Mars. Scientific missions in orbit around the planet had previously discovered high concentrations of hematite on top of the ridge, an iron‐oxide mineral that commonly forms in water. However, it was not clear from orbit if such conditions existed at the time of the deposition of the sediments (around 3.5 billion years ago) or occurred much later during “diagenesis,” after deposition of the sediments and up to their transformation into rocks. On the surface, the rover did not observe significant differences between the ridge and the terrains encountered before it, except for small, dark geologic features that formed during diagenesis. Their analysis by the ChemCam instrument revealed that these features are composed of hematite—the same iron‐oxide mineral that was observed from orbit—and, interestingly, that the iron required to form them was removed from the adjacent rocks by groundwaters. As such, it appears that groundwaters played an important role in shaping Vera Rubin ridge, and thus partially obscure interpretations on the environmental conditions that existed on the surface of Mars at the time of sedimentation.
Key Points
Images from the Curiosity rover show the presence of dark‐toned diagenetic features at Vera Rubin ridge
ChemCam analyses of these features point toward an Fe‐oxide composition, consistent with crystalline hematite
Depletion of Fe and Mn in bleached halos around the Fe‐oxide features indicates mobility of Fe and Mn during the later stages of diagenesis
Metal implants have been preferentially used in THA due to its biocompatibility, mechanical stability and durability. Yet concerns have emerged regarding their potential to release metallic ions, ...leading to long-term adverse effects, including carcinogenicity. This study aimed to investigate the risk of cancer development in patients with orthopaedic metal implants in total hip arthroplasty (THA).
Patients with THA conducted at a local tertiary implant centre from 2001-2008 were linked to the local cancer registry and followed up to the end of 2023. Standardized incidence ratios (SIRs) for cancer incidence and its confidence interval by Poisson distribution were calculated. Survival analysis was depicted using the Kaplan-Meier method, and the log-rank test was used to assess the differences across groups.
The study cohort included 388 patients and 53 cancers diagnosed during follow-up, at least 5 years post THA. All-site cancer risks were increased in patients with THA (SIR: 1.97; 95% CI: 1.48-2.46), validated with chi-square analysis (chi-square = 15.2551, N = 100,388,
< 0.01). A statistically significant increase in multiple site-specific cancers including haematological cancers were identified.
Patients with THA were found to have an increased risk for cancer compared to the general population during a mean follow-up of 16 years.
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•Stochastic-fuzzy-based fractional programming is developed to optimize ratio problem.•It is capable of reflecting conflicting objectives and complex uncertainties.•Results reveal ...that uncertainties remarkably impact marginal benefit of water use.•Irrigation efficiency is the key factor affecting salt-leaching water allocation.•Sustainable water-resources management alternatives in arid region are suggested.
In this study, a stochastic-fuzzy-based fractional programming (SFFP) method is advanced for optimizing water-resources allocation and soil-salinity control under uncertainty. The developed method can address ratio objective optimization problems of complex system in association with stochastic and fuzzy uncertainties, which can help gain in-depth analysis of the interrelationships between marginal effectiveness and system reliability. Then, SFFP is applied to an irrigation region in the lower reach of Amu Darya River basin, where linear crop yield-salinity functions and salt-leaching functions are introduced into the modeling formulation for reflecting the complicated interactions among water resources, soil salinity, arable land, and electricity supply. Solutions under 96 scenarios related to different irrigation efficiencies, water availabilities, and electricity supplies have been obtained. Our findings are: i) increased water availability, electricity supply, and irrigation efficiency result in high marginal benefit; ii) irrigation efficiency is the key factor influencing water allocation patterns for crop irrigation and salt-leaching, promotion of which can facilitate mitigating economic and environmental losses in the water-deficit and soil-salinized region; iii) leaching water allocation patterns for soil-salinity washing is related to salinity characters of crops and regions, and boosting drought- and salt-tolerance crop can be effective in adaption to risks of water scarcity and land salinization. Compared to the conventional approaches, SFFP can generate more flexible alternatives and achieve higher marginal effectiveness. These findings can provide effective decision support to identify desired water management strategies under multiple uncertainties for supporting agricultural sustainability in arid regions.
Summary
Background
Epidemiologic evidence on coffee consumption reducing the risk of gallstone disease has been contradictory.
Aim
To perform a meta‐analysis of observational studies, to investigate ...an association and dose–response of coffee consumption with gallstone disease.
Methods
We used PubMed and EMBASE databases to identify all published studies before June 2015. A random‐effects model was used to compute a pooled relative risk (RR) and corresponding 95% confidence intervals (CIs).
Results
One case–control study and five prospective cohort studies (with seven cohorts) involving 227 749 participants and 11 477 gallstone disease cases were included. Coffee consumption was significantly associated with a reduced risk of gallstone disease (RR, 0.83; 95% CI, 0.76 to 0.89; I2 = 35.9%), based on prospective studies; specifically, we observed an inverse relation in females, but not in males. The case–control study did not reveal any association between coffee and gallstone disease (OR, 0.99; 95% CI, 0.64 to 1.53). In a dose–response analysis, the RR of gallstone disease was 0.95 (95% CI, 0.91 to 1.00; P = 0.049) per 1 cup/day of coffee consumption. A significant nonlinear dose–response association was also identified (P for nonlinearity = 0.0106). For people who drank 2, 4 and 6 cups of coffee per day, the estimated RRs of gallstone disease were 0.89 (95% CI, 0.79 to 0.99), 0.81 (95% CI, 0.72 to 0.92) and 0.75 (95% CI, 0.64 to 0.88), respectively, compared with the lowest level drinkers.
Conclusion
This study suggests that coffee consumption is related to a significantly decreased risk of gallstone disease.
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