336 research outputs found
FAST observations of an extremely active episode of FRB 20201124A: IV. Spin Period Search
We report the properties of more than 800 bursts detected from the repeating
fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter
Aperture Spherical radio telescope (FAST) during an extremely active episode on
UTC September 25th-28th, 2021 in a series of four papers. In this fourth paper
of the series, we present a systematic search of the spin period and linear
acceleration of the source object from both 996 individual pulse peaks and the
dedispersed time series. No credible spin period was found from this data set.
We rule out the presence of significant periodicity in the range between 1 ms
to 100 s with a pulse duty cycle (when the profile is defined
by a von-Mises function, not a boxcar function) and linear acceleration up to
m s in each of the four one-hour observing sessions, and up to
m s in all 4 days. These searches contest theoretical scenarios
involving a 1 ms to 100 s isolated magnetar/pulsar with surface magnetic field
G and a small duty cycle (such as in a polar-cap emission mode) or a
pulsar with a companion star or black hole up to 100 M and
hours. We also perform a periodicity search of the fine structures and
identify 53 unrelated millisecond-timescale "periods" in multi-components with
the highest significance of 3.9 . The "periods" recovered from the fine
structures are neither consistent nor harmonically related. Thus they are not
likely to come from a spin period. We caution against claiming spin periodicity
with significance below 4 with multi-components from one-off
FRBs. We discuss the implications of our results and the possible connections
between FRB multi-components and pulsar micro-structures.Comment: Accepted by Research in Astronomy and Astrophysics (RAA
CRAFTS for Fast Radio Bursts Extending the dispersion-fluence relation with new FRBs detected by FAST
We report three new FRBs discovered by the Five-hundred-meter Aperture
Spherical radio Telescope (FAST), namely FRB 181017.J0036+11, FRB 181118 and
FRB 181130, through the Commensal Radio Astronomy FAST Survey (CRAFTS).
Together with FRB 181123 that was reported earlier, all four FAST-discovered
FRBs share the same characteristics of low fluence (0.2 Jy ms) and high
dispersion measure (DM, \dmu), consistent with the anti-correlation
between DM and fluence of the entire FRB population. FRB 181118 and FRB 181130
exhibit band-limited features. FRB 181130 is prominently scattered
( ms) at 1.25 GHz. FRB 181017.J0036+11 has full-bandwidth
emission with a fluence of 0.042 Jy ms, which is one of the faintest FRB
sources detected so far. CRAFTS starts to built a new sample of FRBs that fills
the region for more distant and fainter FRBs in the fluence- diagram,
previously out of reach of other surveys. The implied all sky event rate of
FRBs is sky day at the
confidence interval above 0.0146 Jy ms. We also demonstrate here that the
probability density function of CRAFTS FRB detections is sensitive to the
assumed intrinsic FRB luminosity function and cosmological evolution, which may
be further constrained with more discoveries.Comment: 9 Pages, 4 Plots and 1 Table. The Astrophysical Journal Letter
Accepte
The Changing Role of Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma: A Updated Systemic Review and Network Meta-Analysis
Background and Objective: Both induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT; IC+CCRT) and CCRT plus adjuvant chemotherapy (AC; CCRT+AC) are standard treatments for advanced nasopharyngeal carcinoma (NPC). However, no prospective randomized trials comparing these two approaches have been published yet. We conducted this network meta-analysis to address this clinical question.Method: We recruited randomized clinical trials involving patients with advanced NPC randomly allocated to IC+CCRT, CCRT+AC, CCRT, or radiotherapy (RT) alone. Pairwise meta-analysis was first conducted, then network meta-analysis was performed using the frequentist approach. Effect size was expressed as hazard ratio (HR) and 95% confidence interval (CI).Results: Overall, 12 trials involving 3,248 patients were recruited for this study, with 555 receiving IC+CCRT, 840 receiving CCRT+AC, 1,039 receiving CCRT, and 814 receiving radiotherapy (RT) alone. IC+CCRT achieved significantly better overall survival ([HR], 0.69; 95% [CI], 0.51–0.92), distant metastasis-free survival (HR, 0.58; 95% CI, 0.44–0.78), and locoregional recurrence-free survival (HR, 0.67; 95% CI, 0.47–0.98) than CCRT. However, survival outcomes did not significantly differ between IC+CCRT and CCRT+AC, or between CCRT+AC and CCRT arms for all the endpoints. As expected, RT alone is the poorest treatment. In terms of P-score, IC+CCRT ranked best for overall survival (96.1%), distant metastasis-free survival (99.0%) and locoregional recurrence-free survival (87.1%).Conclusions: IC+CCRT may be a better and more promising treatment strategy for advanced NPC; however, head-to-head randomized trials comparing IC-CCRT with CCRT-AC are warranted
Spectra of Free Diquark in the Bethe-Salpeter Approach
In this work, we employ the Bethe-Salpeter (B-S) equation to investigate the
spectra of free diquarks and their B-S wave functions. We find that the B-S
approach can be consistently applied to study the diqaurks with two heavy
quarks or one heavy and one light quarks, but for two light-quark systems, the
results are not reliable. There are a few free parameters in the whole scenario
which can only be fixed phenomenologically. Thus, to determine them, one has to
study baryons which are composed of quarks and diquarks.Comment: 16 pages, no figure
FAST observations of an extremely active episode of FRB 20201124A: III. Polarimetry
As the third paper in the multiple-part series, we report the statistical
properties of radio bursts detected from the repeating fast radio burst (FRB)
source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio
telescope (FAST) during an extremely active episode between the 25th and the
28th of September 2021 (UT). We focus on the polarisation properties of 536
bright bursts with . We found that the Faraday rotation
measures (RMs) monotonically dropped from to in the 4-day window. The RM values were compatible with
the values ( to ) reported 4 month ago (Xu et
al. 2022). However, the RM evolution rate in the current observation window was
at least an order of magnitude smaller than the one ($\sim 500\ {\rm rad \
m^{-2}\, day^{-1}}\le 1\ {\rm rad \ m^{-2} day^{-1}}L/IV/I\sigma$) were observed in 33% of
all bursts. The polarisation of single pulses seems to follow certain complex
trajectories on the Poincar\'e sphere, which may shed light on the radiation
mechanism at the source or the plasma properties along the path of FRB
propagation.Comment: 25 pages, 16 figures. Accepted by Research in Astronomy and
Astrophysics (RAA
Selection of Pru p 3 hypoallergenic peach and nectarine varieties
To the Editor, Peach is an important fruit consumed worldwide. However, it is also one of the most frequently reported allergenic fruits.1 Component diagnosis of peach allergy indicates Pru p 1, Pru p 2, Pru p 3, Pru p 4, Pru p 7, and Pru p 9 are involved.2, 3 Pru p 3 is the dominant allergen responsible for severe allergic reaction,4 and it is considered to be the primary sensitizer to other LTPs in Mediterranean and Central Europe.5 The levels of Pru p 3 differ between varieties.6 To date, measurement of Pru p 3 in a limited number of peach and nectarines from Spain, United States, and Italy has been reported.7 Significant variation of allergen concentration in processed foods containing peach has also been observed.8 The content of Pru p 3 of peach/nectarine determines the potential risk for peach allergic patients. China is the origin of peach with representative genetic diversity to be explored for hypoallergenic varieties.9 A core collection of 103 varieties cultivated in Jiaxing, Zhejiang Province were selected to represent this diversity, including 23 nectarines and 80 peach varieties (with fruit hair, round or flat, 77 cultivated, three wild) (Table S1). The soluble solid content (SSC), ripening date, and peach aroma intensity were recorded. Specific methods are detailed in the Supporting Information. Pru p 3 was quantified by ELISA based on our previous research.6info:eu-repo/semantics/publishedVersio
mammalian target of rapamycin complex 2 controls folding and stability of Akt and protein kinase C
The target of rapamycin (TOR), as part of the rapamycinsensitive TOR complex 1 (TORC1), regulates various aspects of protein synthesis. Whether TOR functions in this process as part of TORC2 remains to be elucidated. Here, we demonstrate that mTOR, SIN1 and rictor, components of mammalian (m)TORC2, are required for phosphorylation of Akt and conventional protein kinase C (PKC) at the turn motif (TM) site. This TORC2 function is growth factor independent and conserved from yeast to mammals. TM site phosphorylation facilitates carboxyl-terminal folding and stabilizes newly synthesized Akt and PKC by interacting with conserved basic residues in the kinase domain. Without TM site phosphorylation, Akt becomes protected by the molecular chaperone Hsp90 from ubiquitination-mediated proteasome degradation. Finally, we demonstrate that mTORC2 independently controls the Akt TM and HM sites in vivo and can directly phosphorylate both sites in vitro. Our studies uncover a novel function of the TOR pathway in regulating protein folding and stability, processes that are most likely linked to the functions of TOR in protein synthesis
Atypical radio pulsations from magnetar SGR 1935+2154
Magnetars are neutron stars with extremely strong magnetic fields, frequently
powering high-energy activity in X-rays. Pulsed radio emission following some
X-ray outbursts have been detected, albeit its physical origin is unclear. It
has long been speculated that the origin of magnetars' radio signals is
different from those from canonical pulsars, although convincing evidence is
still lacking. Five months after magnetar SGR 1935+2154's X-ray outburst and
its associated Fast Radio Burst (FRB) 20200428, a radio pulsar phase was
discovered. Here we report the discovery of X-ray spectral hardening associated
with the emergence of periodic radio pulsations from SGR 1935+2154 and a
detailed analysis of the properties of the radio pulses. The complex radio
pulse morphology, which contains both narrow-band emission and frequency
drifts, has not been seen before in other magnetars, but is similar to those of
repeating FRBs - even though the luminosities are many orders of magnitude
different. The observations suggest that radio emission originates from the
outer magnetosphere of the magnetar, and the surface heating due to the
bombardment of inward-going particles from the radio emission region is
responsible for the observed X-ray spectral hardening.Comment: 47 pages, 11 figure
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