1,072 research outputs found
A double peaked pulse profile observed in GX 1+4
The hard X-ray pulsar GX 1+4 was observed several times in the last few years
with a pair of balloon-borne Xenon filled Multi-cell Proportional Counters
(XMPC). In a balloon flight made on 22 March 1995, the source was detected in a
bright state, the average observed source count rate being per
detector. X-ray pulsations with a period of s were detected in
the source with a broad double peak pulse feature. When observed in December
1993 with the same instrument, the pulse profile of GX 1+4 showed a single
peak. This change in the pulse profile to a double pulse structure in about 15
months indicates either activation of the opposite pole of the neutron star if
the magnetic field is asymmetric or possibly a change in the beam pattern, from
a pencil beam to a fan beam. Assuming a fan beam configuration, the pulse
profile is used to find the inclinations of the magnetic axis and the viewing
axis with the spin axis. The derived angles support the GINGA observations of a
dip in the pulse profile which was resolved to have a local maximum in one of
the observations and was explained with resonance scattering of cyclotron line
energy photons by the accretion column (Makishima et al., \markcite{maki1988},
Dotani et al., \markcite{dotani1989}.). Compared to our previous observation of
the same source with the same telescope (Rao et al., \markcite{rao1994}) a
period change rate of is obtained which is the lowest rate
of change of period for this source since its discovery. Average pulse fraction
in the hard X-ray range is low (30%), consistent with its anti correlation with
luminosity as reported by us earlier (Rao et al., \markcite{rao1994}) and the
observed spectrum is very hard (power law photon index ).Comment: 10 pages, to appear in A&
A Multicoloured View of 2S 0114+650
We report the results of radio and X-ray observations of the high mass X-ray
binary 2S 0114+650, made with the Giant Meterwave Radio Telescope and the Rossi
X-ray Timing Explorer respectively. No emission was detected at radio
wavelengths. The neutral hydrogen column density was found to vary over the
orbital period, while no variability over the the super-orbital period was
observed. We discuss the causes of the observed relationships and the
implications for the underlying mechanisms.Comment: 4 pages, 2 figures; to appear in proceedings for "The multicoloured
landscape of compact objects and their explosive progenitors", Cefalu,
Sicily, 2006 June 11-24, AIP, submitte
Systems Medicine of Cancer: Bringing Together Clinical Data and Nonlinear Dynamics of Genetic Networks.
Editoria
Women's Intentions to Engage in Risk-Reducing Behaviours after Receiving Personal Ovarian Cancer Risk Information: An Experimental Survey Study
Risk stratification using genetic and/or other types of information could identify women at increased ovarian cancer risk. The aim of this study was to examine women's potential reactions to ovarian cancer risk stratification. A total of 1017 women aged 45-75 years took part in an online experimental survey. Women were randomly assigned to one of three experimental conditions describing hypothetical personal results from ovarian cancer risk stratification, and asked to imagine they had received one of three results: (a) 5% lifetime risk due to single nucleotide polymorphisms (SNPs) and lifestyle factors; (b) 10% lifetime risk due to SNPs and lifestyle factors; (c) 10% lifetime risk due to a single rare mutation in a gene. Results: 83% of women indicated interest in having ovarian cancer risk assessment. After receiving their hypothetical risk estimates, 29% of women stated they would have risk-reducing surgery. Choosing risk-reducing surgery over other behavioural responses was associated with having higher surgery self-efficacy and perceived response-efficacy, but not with perceptions of disease threat, i.e., perceived risk or severity, or with experimental condition. A substantial proportion of women age 45-75 years may be open to the idea of surgery to reduce risk of ovarian cancer, even if their absolute lifetime risk is only increased to as little as 5 or 10%
Recruitment, adherence, and retention of endometrial cancer survivors in a behavioural lifestyle programme: the Diet and Exercise in Uterine Cancer Survivors (DEUS) parallel randomised pilot trial
Objective: Healthy eating and physical activity may help endometrial cancer survivors (ECS) improve their quality of life. However, most ECS do not meet the relevant guidelines. This pilot trial aimed to test the study feasibility procedures for a definitive trial of a behavioural lifestyle programme. Design and setting: This 24-week parallel two-arm randomised pilot trial took place in two hospitals in London, UK (April 2015âJune 2016). Participants: Sixty disease-free ECS within 3 years of diagnosis. Interventions: Participants were randomised using minimisation to receive the intervention or care as usual. The âShape-Up following cancer treatmentâ programme used self-monitoring, goal-setting, self-incentives, problem-solving and group social support for 12âhours over 8 weeks to help survivors improve their eating and physical activity. Outcome measures: The main outcome measures were recruitment, adherence, and retention rates. Further outcomes included barriers to participation and feedback on programme satisfaction. Results: Of the 296 potentially eligible ECS, 20% (n=60) were randomly allocated to the active intervention (n=29) or control group (n=31). Three participants in each arm were deemed ineligible after randomisation and excluded from analysis. Twenty participants (77%; 95%âCI 61% to 93%) adhered to the intervention and provided generally favourable feedback. At 24 weeks, 25/26 (96%; 95%âCI 89% to 100%) intervention and 24/28 (86%; 95%âCI 73% to 99%) control participants completed their assessment. No intervention-related adverse events were reported. Among eligible survivors who declined study participation (n=83), inconvenience (78%; 95%âCI 69% to 87%) was the most common barrier. Conclusions: The trial was feasible to deliver based on the a priori feasibility criteria. Enhancing recruitment and adherence in a definitive trial will require designs that promote convenience and consider ECS-reported barriers. Trial registration number: NCT02433080; Pre-results. Trial funding: University College London, St. Bartholomewâs Hospital Nurses League, and NIHR University College London Hospitals Biomedical Research Centre
Low Frequency Radio Observations of GRS1915+105 with GMRT
We present the first detailed low frequency radio measurements of the
galactic microquasar GRS1915+105 with GMRT. Simultaneous observations were
carried out at 610 and 244 MHz. Our data does not show any signature of
spectral turn over even at low radio frequency of 244 MHz. We propose that
while the radio emission at high radio frequencies could predominantly come
from compact jets, the emission at lower frequency originates in the lobes at
the end of the jet which acts like a reservoir of low energy electrons.Comment: 7 pages, 3 figure
Quality of Life after Risk-Reducing Hysterectomy for Endometrial Cancer Prevention: A Systematic Review
Background: Risk-reducing hysterectomy (RRH) is the gold-standard prevention for endometrial cancer (EC). Knowledge of the impact on quality-of-life (QoL) is crucial for decision-making. This systematic review aims to summarise the evidence. Methods: We searched major databases until July 2022 (CRD42022347631). Given the paucity of data on RRH, we also included hysterectomy as treatment for benign disease. We used validated quality-assessment tools, and performed qualitative synthesis of QoL outcomes. Results: Four studies (64 patients) reported on RRH, 25 studies (1268 patients) on hysterectomy as treatment for uterine bleeding. There was moderate risk-of-bias in many studies. Following RRH, three qualitative studies found substantially lowered cancer-worry, with no decision-regret. Oophorectomy (for ovarian cancer prevention) severely impaired menopause-specific QoL and sexual-function, particularly without hormone-replacement. Quantitative studies supported these results, finding low distress and generally high satisfaction. Hysterectomy as treatment of bleeding improved QoL, resulted in high satisfaction, and no change or improvements in sexual and urinary function, although small numbers reported worsening. Conclusions: There is very limited evidence on QoL after RRH. Whilst there are benefits, most adverse consequences arise from oophorectomy. Benign hysterectomy allows for some limited comparison; however, more research is needed for outcomes in the population of women at increased EC-risk
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