Communication between plant cells and interacting microorganisms requires the secretion and uptake of functional molecules to and from the extracellular environment and is essential for the survival ...of both plants and their pathogens. Extracellular vesicles (EVs) are lipid bilayer-enclosed spheres that deliver RNA, protein, and metabolite cargos from donor to recipient cells and participate in many cellular processes. Emerging evidencehas shown that both plant and microbial EVs play important roles in cross-kingdom molecular exchange between hosts and interacting microbes to modulate host immunity and pathogen virulence. Recent studies revealed that plant EVs function as a defense system by encasing and delivering small RNAs (sRNAs) into pathogens, thereby mediating cross-species and cross-kingdom RNA interference to silence virulence-related genes. This review focuses on the latest advances in our understanding of plant and microbial EVs and their roles in transporting regulatory molecules, especially sRNAs, between hosts and pathogens. EV biogenesis and secretion are also discussed, as EV function relies on these important processes.
We present the results of a multiwavelength campaign targeting FRB 20201124A, the third closest repeating fast radio burst (FRB), which was recently localized in a nearby (
z
= 0.0978) galaxy. Deep ...VLA observations led to the detection of quiescent radio emission, which was also marginally visible in X-rays with
Chandra
. Imaging at 22 GHz allowed us to resolve the source on a scale of ≳1″ and locate it at the position of the FRB, within an error of 0.2″. The EVN and e-MERLIN observations sampled small angular scales, from 2 to 100 mas, providing tight upper limits on the presence of a compact source and evidence for diffuse radio emission. We argue that this emission is associated with enhanced star formation activity in the proximity of the FRB, corresponding to a star formation rate (SFR) of ≈10
M
⊙
yr
−1
. The surface SFR at the location of FRB 20201124A is two orders of magnitude larger than what is typically observed in other precisely localized FRBs. Such a high SFR is indicative of this FRB source being a newborn magnetar produced from a supernova explosion of a massive star progenitor. Upper limits to the X-ray counterparts of 49 radio bursts observed in our simultaneous FAST, SRT, and
Chandra
campaign are consistent with a magnetar scenario.
Clostridioides difficile is considered an urgent threat to human health by the US Centers for Disease Control and Prevention. In recent years, C. difficile has been reported increasingly as a cause ...of gastrointestinal disease in children, and the prevalence of hospital-acquired C. difficile infection and community-acquired CDI in children is increasing.
To perform a systematic review and meta-analysis of risk factors for CDI in children.
MEDLINE/PubMed, EMBASE, Web of Science, Scopus, OVID, China National Knowledge Infrastructure, Wanfang (Chinese), SinoMed (Chinese) and Weipu (Chinese) were searched from inception to 12th January 2022. Observational studies (cohort, case–control and cross-sectional) on CDI in children were included in the analysis. Data were pooled using a fixed or random-effects model, and odds ratios (OR) were calculated.
In total, 25 observational studies were included in the analysis. Prior antibiotic exposure OR 1.93, 95% confidence interval (CI) 1.25–2.97, prolonged hospitalization (OR 14.68, 95% CI 13.24–16.28), history of hospitalization (OR 3.67, 95% CI 1.91–7.06), gastric acid suppressants (OR 1.96, 95% CI 1.41–2.73), male gender (OR 1.18, 95% CI 1.05–1.32), neoplastic disease (OR 3.40, 95% CI, 2.85–4.07), immunodeficiency (OR 4.18, 95% CI 3.25–5.37), solid organ transplantation (OR 4.56, 95% CI 3.95–5.27) and enteral feeding (OR 2.21, 95% CI 1.05–4.62) were associated with increased risk of CDI.
This systematic review and meta-analysis provides further evidence for the susceptibility factors of CDI to improve clinicians' awareness of CDI, and prevent C. difficile-associated diarrhoea in children.
Abstract
PSR J2150+3427 is a 0.654 s pulsar discovered by the Commensal Radio Astronomy FAST Survey. From the follow-up observations, we find that the pulsar is in a highly eccentric orbit (
e
= ...0.601) with an orbital period of 10.592 days and a projected semimajor axis of 25.488 lt-s. Using 2.7 yr of timing data, we also measured the rate of periastron advance
ω
̇
= 0.0115(4) deg yr
−1
. An estimate for the total mass of the system using the
ω
̇
gives
M
tot
= 2.59(13)
M
⊙
, which is consistent with most of the known double neutron star (DNS) systems and one neutron star (NS)–white dwarf (WD) system named B2303+46. Combining
ω
̇
with the mass function of the system gives the masses of
M
p
< 1.67 and
M
c
> 0.98
M
⊙
for the pulsar and the companion star, respectively. This constraint, along with the spin period and orbital parameters, suggests that it is possibly a DNS system, and we cannot entirely rule out the possibility of an NS–WD system. Future timing observations will vastly improve the uncertainty in
ω
̇
, and are likely to allow the detection of additional relativistic effects, which can be used to modify the values of
M
p
and
M
c
. With a spin-down luminosity of
E
̇
= 5.07(6) × 10
29
erg s
−1
, PSR J2150+3427 is a very low-luminosity pulsar, with only the binary pulsar J2208+4610 having a smaller
E
̇
.
ABSTRACT
We report the phase-connected timing ephemeris, polarization pulse profiles, Faraday rotation measurements, and Rotating-Vector-Model (RVM) fitting results of 12 millisecond pulsars (MSPs) ...discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST survey (CRAFTS). The timing campaigns were carried out with FAST and Arecibo over 3 yr. 11 of the 12 pulsars are in neutron star–white dwarf binary systems, with orbital periods between 2.4 and 100 d. 10 of them have spin periods, companion masses, and orbital eccentricities that are consistent with the theoretical expectations for MSP–Helium white dwarf (He WD) systems. The last binary pulsar (PSR J1912−0952) has a significantly smaller spin frequency and a smaller companion mass, the latter could be caused by a low orbital inclination for the system. Its orbital period of 29 d is well within the range of orbital periods where some MSP–He WD systems have shown anomalous eccentricities, however, the eccentricity of PSR J1912−0952 is typical of what one finds for the remaining MSP–He WD systems.
ABSTRACT
The follow-up timing observations were carried out for 24 pulsars discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. ...We report their phase-connected timing ephemeris, polarization pulse profiles, and Faraday rotation measurements. With their spin periods spanning from 2.995 ms to 4.34 s, their period derivatives were determined to spread between 7.996(8) × 10−21 and 9.83(3) × 10−15 s s−1, which imply that they have characteristic ages from 1.97 × 106 to 5.93 × 109 yr. It is inferred that PSRs J0211+4235 and J0518+2431 are beyond the ‘traditional death line’. PSR J0211+4235 is beyond the ‘death valley’. The death line model of Zhang et al. also cannot explain the radio presence of PSR J0211+4235. This suggests that radiation theory needs to be improved. Besides, ten of the 22 canonical pulsars show nulling phenomena. Moreover, PSR J1617+1123 exhibits variation of emission and J0540+4542 shows subpulse drifting. The DM of five pulsars is larger than the estimated by the YMW16 electron density model, which could suggest that electron density models need updates for higher Galactic latitude regions. PSRs J0447+2447 and J1928−0548 are isolated millisecond pulsars. With their flux densities spanning from 5(1)–553(106) μJy, some of these new pulsars found by FAST are distant, dim, and low-$\dot{E}$ ones and are suitable for testing pulsar emission theories.
Abstract
Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we have recorded over 1.2 × 10
4
single pulses from PSR B0823+26 (J0826+2637) at 1.25 GHz with 500 MHz bandwidth. ...These high-sensitivity observations detected with FAST are unprecedented. We investigated potentially interesting emission features by analyzing the polarimetric individual pulses during the bright state. The average pulse profile has a weak postcursor component and a wide interpulse along with a narrow main pulse. The pulse energy distribution of the main pulse shows the presence of triple emission modes. When the emission ceases in the main pulse component, low-level emission in the interpulse component is detected, whereas the absence of any emission in the postcursor component is shown. In the postcursor emission region, bright pulses are detected in 422 rotations with the relative pulse energy described by a power-law distribution with index of −2.52 ± 0.09, while the peak flux density ratio appears to follow a logarithmic normal distribution. The intervals between bright pulses can be described with a Poisson process with the occurrence rate estimated to be one bright pulse every 14 s. The fluctuation spectral analysis reveals the existence of a form of periodic amplitude modulation unrelated to subpulse drifting in both the main pulse and interpulse components. Furthermore, the modulation patterns in the main pulse and interpulse are found to be locked in pulse longitude, signifying some information transfer between the two magnetic polar regions.
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