67 research outputs found
Flux density measurements for 32 pulsars in the 20 cm band
Flux density measurements provide fundamental observational parameters that
describe a pulsar. In the current pulsar catalogue, 27% of radio pulsars have
no flux density measurement in the 20 cm observing band. Here, we present the
first measurements of the flux densities in this band for 32 pulsars observed
using the Parkes radio telescope and provide updated pulse profiles for these
pulsars. We have used both archival and new observations to make these
measurements. Various schemes exist for measuring flux densities. We show how
the flux densities measured vary between these methods and how the presence of
radio-frequency-interference will bias flux density measurementsComment: Accepted by RA
Probing the Emission States of PSR J1107−5907
The emission from PSR J1107−5907 is erratic. Sometimes the radio pulse is undetectable, at other times the pulsed emission is weak, and for short durations the emission can be very bright. In order to improve our understanding of these state changes, we have identified archival data sets from the Parkes radio telescope in which the bright emission is present, and find that the emission never switches from the bright state to the weak state, but instead always transitions to the "off" state. Previous work had suggested the identification of the "off" state as an extreme manifestation of the weak state. However, the connection between the "off" and bright emission reported here suggests that the emission can be interpreted as undergoing only two emission states: a "bursting" state consisting of both bright pulses and nulls, and the weak emission state
A single pulse study of PSR J1022+1001
Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we
have recorded 10^5 single pulses from PSR J1022+1001. We studied the
polarization properties, their energy distribution and their times of arrival.
This is only possible with the high sensitivity available using FAST. There is
no indication that PSR~J1022+1001 exhibits giant pulse, nulling or traditional
mode changing phenomena. The energy in the leading and trailing components of
the integrated profile is shown to be correlated. The degree of both linear and
circular polarization increases with the pulse flux density for individual
pulses. Our data indicates that pulse jitter leads to an excess noise in the
timing residuals of 67 ns when scaled to one hour, which is consistent with Liu
et al. (2015). We have unsuccessfully trialled various methods to improve
timing precision through the selection of specific single pulses. Our work
demonstrates that FAST can detect individual pulses from pulsars that are
observed in order to detect and study gravitational waves. This capability
enables detailed studies, and parameterisation, of the noise processes that
affect the sensitivity of a pulsar timing array.Comment: Accepted by Ap
Wide Bandwidth Observations of Pulsars C, D and J in 47 Tucanae
We report the first wideband observations of pulsars C, D and J in the
globular cluster 47Tucanae (NGC 104) using the Ultra-Wideband Low (UWL)
receiver system recently installed on the Parkes 64 m radio telescope. The wide
frequency range of the UWL receiver (704-4032 MHz), along with the
well-calibrated system, allowed us to obtain flux density measurements and
polarization pulse profiles. The mean pulse profiles have significant linear
and circular polarization, allowing for determination of the Faraday rotation
measure for each pulsar. Precise measurements of the dispersion measures show a
significant deviation in the value for pulsar D compared to earlier results.
Searches for new pulsars in the cluster are on-going and we have determined
optimal bands for such searches using the Parkes UWL receiver system
Probing the Emission States of PSR J1107−5907
The emission from PSR J1107−5907 is erratic. Sometimes the radio pulse is undetectable, at other times the pulsed emission is weak, and for short durations the emission can be very bright. In order to improve our understanding of these state changes, we have identified archival data sets from the Parkes radio telescope in which the bright emission is present, and find that the emission never switches from the bright state to the weak state, but instead always transitions to the "off" state. Previous work had suggested the identification of the "off" state as an extreme manifestation of the weak state. However, the connection between the "off" and bright emission reported here suggests that the emission can be interpreted as undergoing only two emission states: a "bursting" state consisting of both bright pulses and nulls, and the weak emission state
Overall survival and cancer-specific survival were improved in local treatment of metastatic prostate cancer
BackgroundFor metastatic prostate cancer (mPCa), radical prostatectomy (RP) and radiation therapy (RT) may improve overall survival (OS) and cancer-specific survival (CSS). Compared with RT, RP shows significant advantages in improving patient outcomes. External beam radiation therapy (EBRT) even slightly elevates CSM with no statistical difference in OS compared with no local treatment (NLT).ObjectiveTo evaluate OS and CSS after local treatment (LT) (including RP and RT) versus NLT in mPCa.Design, setting, and participantsWithin the Surveillance, Epidemiology and End Results (SEER) database (2000-2018), 20098 patients with metastatic prostate cancer were selected in this study, of which 19433 patients had no local treatment, 377 patients with radical prostate treatment, and 288 patients with RT.Outcome measurements and statistical analysisMultivariable competing risks regression analysis after propensity score matching (PSM) was used to calculate CSM. Multivariable Cox regression analysis was used to identify the risk factors. Kaplan-Meier methods were used to calculate OS.Results and limitationsA total of 20098 patients were included: NLT (n = 19433), RP (n=377) and RT (n=288). In a competing risk regression analysis after PSM (ratio 1:1), RP resulted in a significantly lower CSM (hazard ratio [HR] 0.36, 95% confidence interval [CI] 0.29-0.45) than NLT, while RT showed a slightly lower CSM (HR 0.77, 95% CI 0.63-0.95). In a competing risk regression analysis after PSM (ratio 1:1), RP led to a lower CSM (HR 0.56, 95% CI 0.41-0.76) versus RT. As for all-cause mortality (ACM), RP (HR 0.37, 95% CI 0.31-0.45) and RT (HR 0.66, 95% CI 0.56-0.79). also showed a downward trend. In terms of OS, RP and RT significantly improved the survival probability compared with NLT, with the effect of RP being more pronounced. Obviously, older age, Gleason scores ≥8, AJCC T3-T4 stage, AJCC N1, AJCC M1b-M1c were all associated with higher CSM (P <0.05). The same results held true for ACM. The limitation of this article is that it is not possible to assess the effect of differences in systemic therapy on CSM in mPCa patients and clinical trials are needed to verify the results.ConclusionsFor patients with mPCa, both RP and RT are beneficial to patients, and the efficacy of RP is better than RT from the perspective of CSM and ACM. Older age, higher gleason scores and the more advanced AJCC TNM stage all put patients at higher risk of dying.Patient summaryA large population-based cancer database showed that in addition to first-line therapy (hormonal treatment), RP and radiotherapy can also benefit patients with mPCa
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