Magnetically gated accretion in an accreting ‘non-magnetic’ white dwarf

White dwarfs are often found in binary systems with orbital periods ranging from tens of minutes to hours in which they can accrete gas from their companion stars. In about 15 per cent of these binaries, the magnetic field of the white dwarf is strong enough (at 106 gauss or more) to channel the accreted matter along field lines onto the magnetic poles1,2. The remaining systems are referred to as ‘non-magnetic’, because until now there has been no evidence that they have a magnetic field that is strong enough to affect the accretion dynamics. Here we report an analysis of archival optical observations of the ‘non-magnetic’ accreting white dwarf in the binary system MV Lyrae, whose light curve displays quasi-periodic bursts of about 30 minutes duration roughly every 2 hours. The timescale and amplitude of these bursts indicate the presence of an unstable, magnetically regulated accretion mode, which in turn implies the existence of magnetically gated accretion3,4,5, in which disk material builds up around the magnetospheric boundary (at the co-rotation radius) and then accretes onto the white dwarf, producing bursts powered by the release of gravitational potential energy. We infer a surface magnetic field strength for the white dwarf in MV Lyrae of between 2 × 104 gauss and 1 × 105 gauss, too low to be detectable by other current methods. Our discovery provides a new way of studying the strength and evolution of magnetic fields in accreting white dwarfs and extends the connections between accretion onto white dwarfs, young stellar objects and neutron stars, for which similar magnetically gated accretion cycles have been identified6,7,8,9

Data Mining and Machine Learning in Astronomy

We review the current state of data mining and machine learning in astronomy. 'Data Mining' can have a somewhat mixed connotation from the point of view of a researcher in this field. If used correctly, it can be a powerful approach, holding the potential to fully exploit the exponentially increasing amount of available data, promising great scientific advance. However, if misused, it can be little more than the black-box application of complex computing algorithms that may give little physical insight, and provide questionable results. Here, we give an overview of the entire data mining process, from data collection through to the interpretation of results. We cover common machine learning algorithms, such as artificial neural networks and support vector machines, applications from a broad range of astronomy, emphasizing those where data mining techniques directly resulted in improved science, and important current and future directions, including probability density functions, parallel algorithms, petascale computing, and the time domain. We conclude that, so long as one carefully selects an appropriate algorithm, and is guided by the astronomical problem at hand, data mining can be very much the powerful tool, and not the questionable black box.Comment: Published in IJMPD. 61 pages, uses ws-ijmpd.cls. Several extra figures, some minor additions to the tex

Quality of life and sexual functioning among endometrial cancer patients treated with one week adjuvant high-dose-rate vaginal brachytherapy schedule

Purpose: To examine quality of life (QOL) and sexual functioning in a series of patients with intermediate- and high-intermediate risk endometrial cancer, treated with exclusive adjuvant one week high-dose-rate (HDR) vaginal brachytherapy (VBT) schedule. Material and methods: Between July 2008 and October 2013, 55 patients with diagnosis of endometrial cancer were treated with adjuvant exclusive VBT. All patients had undergone surgical treatment with a laparotomy approach before VBT. Post-operative VBT was administered 6-8 weeks after surgery. Treatment was delivered to vaginal vault using Nucletron HDR unit with iridium-192 source at a dose of 21 Gy/3 fractions of 7 Gy each, three times a week, every other day, prescribed at 0.5 cm depth of vaginal wall, and 3 cm in length from the apex. QOL was assessed using European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire Core-30 (QLQ-C30), and EORTC cancer-specific quality of life questionnaire (QLQ-CX24). Results: Median follow-up time was 92 months (range, 42-162 months). Questionnaires were carried out respectively at 1, 3, 6, 12, 24, 36, 48, and 60 months after the end of BT. Response rate to questionnaires was 100% (n = 55). Nineteen patients (35%) answered all the questions of surveys, while 36 patients (65%) completed the surveys, except for questions on sex activity, vaginal function, and sex enjoyment. Longitudinal analysis during 5-year follow-up period showed a statistically significant trend towards worsening of fatigue, constipation, and diarrhea. Overall physical functioning and role functioning was not impaired after VBT. Over the time, sex enjoyment improved, except for elderly patients. For emotional functioning, sex worry and social functioning presented no significant time-related effect. Conclusions: One week brachytherapy schedule to vaginal cuff is generally well-tolerated. QOL does not worsen after applying vaginal brachytherapy. brachytherapy; endometrial carcinoma; fatigue; quality of life; sexual disfunction

Rms-flux relation in the optical fast variability data of BL Lacertae object S5 0716+714

The possibility that BL Lac S5 0716+714 exhibits a linear root mean square (rms)-flux relation in its IntraDay Variability (IDV) is analysed. The results may be used as an argument in the existing debate regarding the source of optical IDV in Active Galactic Nuclei. 63 time series in different optical bands were used. A linear rms-flux relation at a confidence level higher than 65% was recovered for less than 8% of the cases. We were able to check if the magnitude is log-normally distributed for eight timeseries and found, with a confidence > 95%, that this is not the case.Comment: Accepted by Astrophysics and Space Scienc