A deep learning approach to diabetic blood glucose prediction

We consider the question of 30-minute prediction of blood glucose levels measured by continuous glucose monitoring devices, using clinical data. While most studies of this nature deal with one patient at a time, we take a certain percentage of patients in the data set as training data, and test on the remainder of the patients; i.e., the machine need not re-calibrate on the new patients in the data set. We demonstrate how deep learning can outperform shallow networks in this example. One novelty is to demonstrate how a parsimonious deep representation can be constructed using domain knowledge

A near-infrared study of the star forming region RCW 34

We report the results of a near-infrared imaging study of a $7.8 \times 7.8$ arcmin$^2$ region centered on the 6.7 GHz methanol maser associated with the RCW 34 star forming region using the 1.4m IRSF telescope at Sutherland. A total of 1283 objects were detected simultaneously in J, H, and K for an exposure time of 10800 seconds. The J-H, H-K two-colour diagram revealed a strong concentration of more than 700 objects with colours similar to what is expected of reddened classical T Tauri stars. The distribution of the objects on the K {\it vs} J-K colour-magnitude diagram is also suggestive that a significant fraction of the 1283 objects is lower mass pre-main sequence stars. We also present the luminosity function for the subset of about 700 pre-main sequence stars and show that it suggests ongoing star formation activity for about $10^7$ years. An examination of the spatial distribution of the pre-main sequence stars shows that the fainter (older) part of the population is more dispersed over the observed region and the brighter (younger) subset is more concentrated around the position of the O8.5V star. This suggests that the physical effects of the O8.5V star and the two early B-type stars on the remainder of the cloud out of which they formed, could have played a role in the onset of the more recent episode of star formation in RCW 34.Comment: Accepted for publication in The Astronomical Journa

How do methanol masers manage to appear in the youngest star vicinities and isolated molecular clumps?

General characteristics of methanol (CH3OH) maser emission are summarized. It is shown that methanol maser sources are concentrated in the spiral arms. Most of the methanol maser sources from the Perseus arm are associated with embedded stellar clusters and a considerable portion is situated close to compact HII regions. Almost 1/3 of the Perseus Arm sources lie at the edges of optically identified HII regions which means that massive star formation in the Perseus Arm is to a great extent triggered by local phenomena. A multiline analysis of the methanol masers allows us to determine the physical parameters in the regions of maser formation. Maser modelling shows that class II methanol masers can be pumped by the radiation of the warm dust as well as by free-free emission of a hypercompact region hcHII with a turnover frequency exceeding 100 GHz. Methanol masers of both classes can reside in the vicinity of hcHIIs. Modelling shows that periodic changes of maser fluxes can be reproduced by variations of the dust temperature by a few percent which may be caused by variations in the brightness of the central young stellar object reflecting the character of the accretion process. Sensitive observations have shown that the masers with low flux densities can still have considerable amplification factors. The analysis of class I maser surveys allows us to identify four distinct regimes that differ by the series of their brightest lines.Comment: 8 pages, 4 figures, invited presentation at IAU242 "Astrophysical Masers and their environments

Inferences from the kinematic properties of 6.7 GHz methanol masers

Context. It is now well established that the strong and widespread 6.7 GHz methanol masers are associated with young high mass stars. A still unsolved question is where in the circumstellar environment the masers arise. Aims.We address this question by considering an ensemble of rest frame maser velocities of 337 maser features. Methods. The CS(2-1) spectra of 63 methanol maser sources were used to derive systemic velocities and velocity dispersion of the thermal gas. Using the systemic velocities and the velocities of the 337 maser features in the 63 sources, a single distribution of rest frame maser velocities was constructed. This distribution as well as other kinematic information about the masers are used to evaluate four proposed scenarios for where the masers might arise in the circumstellar environment. Results.It is shown that kinematically the masers are not associated with hot cores. We also argue that the scenario in which the masers are associated with an external generated planar shock that propagates into a rotating core cannot explain the observed kinematic properties of the masers. It was found that a simple Keplerian-like disk model is consistent with the observed distribution of rest frame maser velocities. Although outflows have the potential to explain the data, it was not possible to fully test this possibility due to the diverse nature of outflows

On the Identification of High Mass Star Forming Regions using IRAS: Contamination by Low-Mass Protostars

We present the results of a survey of a small sample (14) of low-mass protostars (L_IR < 10^3 Lsun) for 6.7 GHz methanol maser emission performed using the ATNF Parkes radio telescope. No new masers were discovered. We find that the lower luminosity limit for maser emission is near 10^3 Lsun, by comparison of the sources in our sample with previously detected methanol maser sources. We examine the IRAS properties of our sample and compare them with sources previously observed for methanol maser emission, almost all of which satisfy the Wood & Churchwell criterion for selecting candidate UCHII regions. We find that about half of our sample satisfy this criterion, and in addition almost all of this subgroup have integrated fluxes between 25 and 60 microns that are similar to sources with detectable methanol maser emission. By identifying a number of low-mass protostars in this work and from the literature that satisfy the Wood & Churchwell criterion for candidate UCHII regions, we show conclusively for the first time that the fainter flux end of their sample is contaminated by lower-mass non-ionizing sources, confirming the suggestion by van der Walt and Ramesh & Sridharan.Comment: 8 pages with 2 figures. Accepted by Ap

New Periodic 6.7 GHz Class II Methanol Maser Associated with G358.460-0.391

Eight new class II methanol masers selected from the 6.7 GHz Methanol Multibeam survey catalogues I and II were monitored at 6.7 GHz with the 26m Hartebeesthoek Radio Astronomy Observatory (HartRAO) radio telescope for three years and seven months, from February 2011 to September 2014. The sources were also observed at 12.2 GHz and two were sufficiently bright to permit monitoring. One of the eight sources, namely G358.460-0.391, was found to show periodic variations at 6.7 GHz. The period was determined and tested for significance using the Lomb-Scargle, epoch-folding and Jurkevich methods, and by fitting a simple analytic function. The best estimate for the period of the 6.7 GHz class II methanol maser line associated with G358.460-0.391 is 220.0 $\pm$ 0.2 day.Comment: 8 pages, 11 figures, accepted for publication in MNRAS. The appendix of 4 pages (with 16 figures) will be published as online versio

Spectral Energy Distributions of 6.7 GHz methanol masers

The 6.7 GHz maser transition of methanol has been found exclusively towards massive star forming regions. A majority of the masers have been found to lack the presence of any associated radio continuum. This could be due to the maser emission originating prior to the formation of an HII region around the central star, or from the central object being too cool to produce a HII region. One way to distinguish between the two scenarios is to determine and model the spectral energy distributions (SEDs) of the masers. We observed a sample of 20 6.7 GHz methanol masers selected from the blind Arecibo survey, from centimeter to submillimeter wavelengths. We combined our observations with existing data from various Galactic plane surveys to determine SEDs from centimeter to near-infrared wavelengths. We find that 70% of the masers do not have any associated radio continuum, with the rest of the sources being associated with hypercompact and ultracompact HII regions. Modeling the SEDs shows them to be consistent with rapidly accreting massive stars, with accretion rates well above 10^{-3} M_sun/yr. The upper limits on the radio continuum are also consistent with any ionized region being confined close to the stellar surface. This confirms the paradigm of 6.7 GHz methanol masers being signposts of early phases of massive star formation, mostly prior to the formation of a hypercompact HII region.Comment: 15 pages, 4 figures; Accepted by A&

Absolute positions of 6.7-GHz methanol masers

The ATCA, MERLIN and VLA interferometers were used to measure the absolute positions of 35 6.7 GHz methanol masers to subarcsecond or higher accuracy. Our measurements represent essential preparatory data for Very Long Baseline Interferometry, which can provide accurate parallax and proper motion determinations of the star-forming regions harboring the masers. Our data also allow associations to be established with infrared sources at different wavelengths. Our findings support the view that the 6.7 GHz masers are associated with the earliest phases of high-mass star formation.Comment: A&A accepted 29 pages, 6 figures, 5 table

The Arecibo Methanol Maser Galactic Plane Survey--I: Data

We present the results of an unbiased survey for 6.7 GHz methanol masers in the Galactic plane carried out using the 305 m Arecibo radio telescope. A total of 18.2 square degrees was surveyed with uniform sampling at 35.2 deg < l < 53.7 deg, |b| < 0.41 deg. The large collecting area of Arecibo and the sensitive C-Band High receiver allowed the survey to be complete at the level of 0.27 Jy making this the most sensitive blind survey carried out to date. We detected a total of 86 sources, 48 of which are new detections. Most of the new detections have a peak flux density below 2 Jy. Many methanol masers are clustered, reflecting the formation of massive stars in clusters.Comment: Accepted by Ap