FITS Files Research Articles

Hypoglycemia Prevention via Personalized Glucose-Insulin Models Identified in Free-Living Conditions.

The objective of this research is to show the effectiveness of individualized hypoglycemia predictive alerts (IHPAs) based on patient-tailored glucose-insulin models (PTMs) for different subjects. Interpatient variability calls for PTMs that have been identified from data collected in free-living conditions during a one-month trial. A new impulse-response (IR) identification technique has been applied to free-living data in order to identify PTMs that are able to predict the future glucose trends and prevent hypoglycemia events. Impulse response has been applied to seven patients with type 1 diabetes (T1D) of the University of Amsterdam Medical Centre. Individualized hypoglycemia predictive alert has been designed for each patient thanks to the good prediction capabilities of PTMs. The PTMs performance is evaluated in terms of index of fitting (FIT), coefficient of determination, and Pearson's correlation coefficient with a population FIT of 63.74%. The IHPAs are evaluated on seven patients with T1D with the aim of predicting in advance (between 45 and 10 minutes) the unavoidable hypoglycemia events; these systems show better performance in terms of sensitivity, precision, and accuracy with respect to previously published results. The proposed work shows the successful results obtained applying the IR to an entire set of patients, participants of a one-month trial. Individualized hypoglycemia predictive alerts are evaluated in terms of hypoglycemia prevention: the use of a PTM allows to detect 84.67% of the hypoglycemia events occurred during a one-month trial on average with less than 0.4% of false alarms. The promising prediction capabilities of PTMs can be a key ingredient for new generations of individualized model predictive control for artificial pancreas.

Marvin: A Tool Kit for Streamlined Access and Visualization of the SDSS-IV MaNGA Data Set

Abstract The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, one of three core programs of the fourth-generation Sloan Digital Sky Survey (SDSS-IV), is producing a massive, high-dimensional integral field spectroscopic data set. However, leveraging the MaNGA data set to address key questions about galaxy formation presents serious data-related challenges due to the combination of its spatially interconnected measurements and sheer volume. For each galaxy, the MaNGA pipelines produce relatively large data files to preserve the spatial correlations of the spectra and measurements, but this comes at the expense of storing the data set in coarse units or “chunks.” This coarse chunking and the total volume of the data make it time-consuming to download and curate locally stored data. Thus, accessing, querying, visually exploring, and performing statistical analyses across the whole data set at a fine-grained scale is extremely challenging using just FITS files. To overcome these challenges, we have developed Marvin, a toolkit consisting of a Python package, Application Programming Interface, and web application utilizing a remote database. Marvin allows users to seamlessly work with MaNGA data by abstracting both remote and local (on-disk) interactions to behind-the-scenes data-handling functions. Combining this capability with additional processing and querying tools, users can create powerful Python workflows that are easy to import and share. Marvin’s web application uses these tools to enable “point-and-click” examination of data cubes and derived maps, as well as search queries for all publicly released MaNGA galaxies. Marvin’s robust and sustainable design minimizes maintenance, while facilitating user-contributed extensions such as high-level analysis code.

An automatic approach of mapping the solar high-resolution image to Helioprojective-Cartesian coordinates system

The ground-based solar high-resolution observation usually only covers a small part of the solar disk, so determining the field of view position of an observed image on the Helioprojective-Cartesian coordinates is the first step in data processing. In the present, most solar physicists manually adjust parameters by trial and error to complete this step, because the mapping information may not be included in the flexible image transport system (FITS) header of a raw image. The manual approach cannot guarantee the accuracy. It is inefficient and has plagued many solar physicists. In this paper, we propose an automatic mapping approach by registering a high-resolution image to a standard calibrated solar full disk using image pre-processing and scale-invariant feature transform (SIFT) technology. Following steps are included. (1) Downsampling and blurring a high-resolution image to roughly fit the scale and the resolution of its corresponding full disk image; (2) scaling the gray level to 256 by local minimum and maximum to meet the requirements of applying the standard OpenCV SIFT processing package; (3) removing the limb-darkening of the reference full disk image with Cartesian to polar coordinate transform method; (4) detecting the feature points by SIFT on both high-resolution and full disk images; (5) matching corresponding point pairs by fast library for approximate nearest neighbors (FLANN); (6) calculating translation, rotation and scale parameters by random sample consensus (RANSAC); (7) recording the registration results in FITS header with standard keywords of the Solar Dynamics Observatory (SDO) image. These keywords can be automatically retrieved by the Solar SoftWare (SSW) system. With this approach, we have successfully registered both active region and quiet sun images observed by the titanium dioxide (TiO) band of the New Vacuum Solar Telescope (NVST) to the continuum of the helioseismic and magnetic imager (HMI) instrument on the SDO, and Hα active region images of NVST to the Global Oscillation Network Group (GONG) with high accuracy (0.25 arcsec for photosphere and 1 arcsec for chromosphere). If a high-resolution image shows bright structures, such as flares, the Hα image of NVST could be registered to 304 A image of the atmospheric imaging assembly (AIA) on SDO with the accuracy of 1 arcsec as well. In addition, the images observed by Hα blue/red wings (±0.7 A) of NVST, TiO of the Goode solar telescope (GST), Hα of the Optical and Near-infrared Solar Eruption Tracer (ONSET) are also successfully registered to SDO/HMI continuum or SDO/AIA 304 A full disk image. Iterative processing is applied to improve accuracy. An automatic SDO or GONG image downloading procedure and an extra interactive user interface are also integrated. This approach has met the requirement of mapping a high-resolution image to the Helioprojective-Cartesian coordinates of full disk. Its weakness is that if a high-resolution image does not show high contrast, such as limb observation of photosphere or quiet sun of chromosphere, it is difficult to get a mapping result, because the whole strategy is based on image feature detection. The procedure will be merged into the observation system of NVST in the future, and will provide great convenience for the solar physicists to use the high-resolution observation data.

Risk factors for development of community-acquired pneumonia in workers of main occupations in production of chrysotile asbestos

Inpatient examination covered 46 workers of main occupations in chrysotile asbestos production, with diagnosed occupational disease “asbestosis”, and reference group comprising 20 healthy workers of the same enterprise. Th e results present comparative analysis of clinical and anamnesis data in dependence on the past pneumonia, studies of immune state in the asbestosis patients and the healthy workers, data on high occurrence of pneumonia in the workers, comparative analysis of respiratory infections occurrence and concomitant diseases according to the outpatients records and medical examinations. Findings are reliable diff erences and earlier respiratory manifestations in the past-pneumonia workers exposed to chrysotile asbestos, higher occurrence (1.3-fold) of chronic bronchitis and severe disorders of bronchial patency. Immune response factors were characterized as pathogenetic links of pneumococcus infectious invasion. Additional risk factors of pneumonia appeared to be frequent respiratory infections, chronic diseases of upper respiratory tract and middle ear, lower functional state of neutrophils, increased auto-reactivity. To evaluate signifi cance of risk factors infl uence, the authors used fi tt ing criterion X2 (chi-square). Intensity of relationships between the risk factor and outcome was evaluated by contingency coeffi cient of Pearson. Signifi cance level (p) for all the calculation was accepted less than 0.05.

AtomNeb: IDL Library for Atomic Data of Ionized Nebulae

Spectra emitted from ionized nebulae typically contain collisionally excited and recombination lines, which can be used to trace physical conditions and chemical abundances of the interstellar medium in our Galaxy and other galaxies. "AtomNeb" is a database containing atomic data stored in the Flexible Image Transport System (FITS) file format, including the data for collisionally excited and recombination lines generally observed in nebular astrophysics. The AtomNeb interface library is equipped with several application programming interface (API) functions developed in the Interactive Data Language (IDL), which can be also used in the GNU Data Language (GDL). This IDL library relies on the FITS file related IDL procedures from the IDL Astronomy User's library. The AtomNeb IDL library, together with the "proEQUIB" IDL library, can be used to perform plasma diagnostics and abundance analysis of emission lines from ionized gaseous nebulae.

Aflak: Visual programming environment enabling end-to-end provenance management for the analysis of astronomical datasets

This paper describes an extendable graphical framework, aflak, which provides a visualization and provenance management environment for the analysis of multi-spectral astronomical datasets. Via its node editor interface, aflak allows the astronomer to compose transforms on input datasets queryable from public astronomical data repositories, then to export the results of the analysis as Flexible Image Transport System (FITS) files, in a manner such that the full provenance of the output data be preserved and reviewable, and that the exported file be usable by other common astronomical analysis software. FITS is the standard of data interchange in astronomy. By embedding aflak’s provenance data into FITS files, we both achieve interoperability with existing software and full reproducibility of the process by which astronomers make discoveries.

Once FITS, Always FITS? Astronomical Infrastructure in Transition

The FITS file format has become the de facto standard for sharing, analyzing, and archiving astronomy data over the last four decades. FITS was adopted by astronomers in the early 1980s to overcome incompatibilities between operating systems. On the back of FITS' success, astronomical data became both backwards compatible and easily shareable. However, new advances in astronomical instrumentation, computational technologies, and analytic techniques have resulted in new data that do not work well within the traditional FITS format. Tensions have arisen between the desire to update the format to meet new analytic challenges and adherence to the original edict for FITS files to be backwards compatible. We examine three inflection points in the governance of FITS: a) initial development and success, b) widespread acceptance and governance by the working group, and c) the challenges to FITS in a new era of increasing data and computational complexity within astronomy.

Fips: An OpenGL based FITS viewer

FITS (Flexible Image Transport System) is a common format for astronomical data storage. It was first standardised in the early 1980s. Even though astronomical data is now processed mostly using software, visual data inspection by a human is still important during equipment or software commissioning and while observing. We present Fips, a cross-platform FITS file viewer open source software. To the best of our knowledge, it is for the first time that the image rendering algorithms are implemented mostly on GPU (graphics processing unit). We show that it is possible to implement a fully-capable FITS viewer using OpenGL interface. We also emphasise the advantages of using GPUs for efficient image handling.

Heasim and skyback simulation tools and their application to the Hitomi mission

We present an introduction to the heasim multimission observation and skyback background, high-energy pseudo Monte Carlo astrophysical simulation tools. Heasim may be used to accurately and efficiently construct flexible image transport system (FITS) event files for simple or composite sources with a wide range of standard and user-defined spatial, spectral, and temporal characteristics. Skyback is designed to enable users to assess the impact of background discrete and diffuse emission on prospective observations, and skyback output may be directly input into heasim. We present a brief overview of heasim and skyback input, algorithms, usage, and output. We also introduce the sxsbranch tool that computes Hitomi soft X-ray spectrometer resolution grade branching ratios, emphasizing its application to simulations. We include several examples of particular relevance to the Hitomi mission.

Study of ambient environment around Asymptotic Giant Branch Carbon Star: IRAS 01142+6306

We studied dust environment such as flux, temperature, mass and inclination angle of the cavity structure around the C-rich Asymptotic giant branch star in 60 μm and 100 μm wavelengths band using Infrared Astronomical Survey. We observed the data of AGB star having IRAS name 01142+6306 corresponding to R.A.(J2000)= 01h 17m 33.504s and Dec.(J2000)= 630 22’ 4.98’. Flexible image transport system image was downloaded from Sky View Observatory; we obtained the surrounding flux density using software Aladinv2.5. The dust color average temperature and mass are found to be 25.08 K and 4.731026 kg (0.00024 Mʘ) respectively. The dust color temperature ranges from 18.76 ± 3.16 K to 33.21 ± 4.07 K. The isolated cavity like structure around AGB star has extension 45.67 parsec and contraction 17.02 parsec was observed using detailed calculation. The core region is found to be edge-on having inclination angle 79.46o. BIBECHANA 16 (2019) 31-40

ACTIN: A tool to calculate stellar activity indices

Magnetic activity in the atmospheres of stars produces a number of spectroscopic signatures that are visible in the shape and strength of spectral lines. These signatures can be used to access, among other things, the variability of the magnetic activity, or its infuence on other parameters such as the measured radial velocity (RV). This latter is of utmost importance for the detection and characterization of planets orbiting other stars. ACTIN is a Python program to calculate stellar activity indices. The program reads input data either from .fits files returned by the pipelines of spectrographs, or from .rdb tables. It extracts automatically the spectral data required to calculate spectral activity indices. The output is an .rdb table, with the calculated stellar activity indices for each date (Julian Date), as well as the RV and Cross-Correlation Function profile parameters, if available. It also outputs timeseries plots of the activity indices and plots the spectral lines used to compute the indices.

FITS Data Source for Apache Spark

We investigate the performance of Apache Spark, a cluster computing framework, for analyzing data from future LSST-like galaxy surveys. Apache Spark attempts to address big data problems have hitherto proved successful in the industry, but its use in the astronomical community still remains limited. We show how to manage complex binary data structures handled in astrophysics experiments such as binary tables stored in FITS files, within a distributed environment. To this purpose, we first designed and implemented a Spark connector to handle sets of arbitrarily large FITS files, called spark-fits. The user interface is such that a simple file “drag-and-drop” to a cluster gives full advantage of the framework. We demonstrate the very high scalability of spark-fits using the LSST fast simulation tool, CoLoRe, and present the methodologies for measuring and tuning the performance bottlenecks for the workloads, scaling up to terabytes of FITS data on the Cloud@VirtualData, located at Universite Paris Sud. We also evaluate its performance on Cori, a High-Performance Computing system located at NERSC, and widely used in the scientific community.

FITS Format for Planetary Surfaces: Definitions, Applications, and Best Practices

Planetary science encompasses a broad number of research fields and brings together several research communities (geologists, astronomers, physicists, geochemists, etc.). Planetary missions produce an impressively growing amount of diverse data requiring an evolution from a mostly manual‐based visual analysis to a more automated and quantitative analysis. Interoperability, openness of data formats, and shared processing techniques are a necessity to efficiently extract scientific information from the data and to guarantee the reproducibility of the scientific results. Unfortunately, the technologies and data formats used by researchers for planetary surface studies and the field of astronomy diverged as these related, but almost completely isolated, domains evolved. In this paper we will describe how a small addition to the Flexible Image Transport System (FITS) standard, widely used in the astronomy investigations, will allow FITS to be more easily used in planetary surface investigations. We will also show how FITS metadata can easily be transformed in the Planetary Data System version 4 metadata archival model and lastly provide example implementations. More than imposing a formal data model, a FITS description for planetary data aims to simplify sharing data across the planetary and astronomy domains and promoting interoperability from raw data formatting to final visualization.

CuFFS: A GPU-accelerated code for Fast Faraday rotation measure Synthesis

Rotation measure (RM) synthesis is a widely used polarization processing algorithm for reconstructing polarized structures along the line of sight. Performing RM synthesis on large datasets produced by telescopes like LOFAR can be computationally intensive as the computational cost is proportional to the product of the number of input frequency channels, the number of output Faraday depth values to be evaluated and the number of lines of sight present in the data cube. The required computational cost is likely to get worse due to the planned large area sky surveys with telescopes like the Low Frequency Array (LOFAR), the Murchison Widefield Array (MWA), and eventually the Square Kilometre Array (SKA). The massively parallel General Purpose Graphical Processing Units (GPGPUs) can be used to execute some of the computationally intensive astronomical image processing algorithms including RM synthesis. In this paper, we present a GPU-accelerated code, called cuFFS or CUDA-accelerated Fast Faraday Synthesis, to perform Faraday rotation measure synthesis. Compared to a fast single-threaded and vectorized CPU implementation, depending on the structure and format of the data cubes, our code achieves an increase in speed of up to two orders of magnitude. During testing, we noticed that the disk I/O when using the Flexible Image Transport System (FITS) data format is a major bottleneck and to reduce the time spent on disk I/O, our code supports the faster HDFITS format in addition to the standard FITS format. The code is written in C with GPU-acceleration achieved using Nvidia's CUDA parallel computing platform. The code is available at https://github.com/sarrvesh/cuFFS.

Dust Structure Around Asymptotic Giant Branch Stars

AbstractThis paper presents mass, temperature profile, and the variation of Planck’s function in different regions around asymptotic giant branch (AGB) stars. The physics of the interstellar medium (ISM) is extremely complex because the medium is very inhomogeneous and is made of regions with fairly diverse physical conditions. We studied the dust environment such as flux, temperature, mass, and inclination angle of the cavity structure around C-rich asymptotic giant branch stars in 60 μm and 100 μm wavelengths band using Infrared Astronomical Survey. We observed the data of AGB stars named IRAS 01142+6306 and IRAS 04369+4501. Flexible image transport system image was downloaded from Sky View Observatory; we obtained the surrounding flux density using software Aladin v2.5. The average dust color temperature and mass are found to be 25.08 K, 23.20 K and 4.73 × ;1026 kg (0.00024 M⊙), 2.58 × 1028 kg (0.013 M⊙), respectively. The dust color temperature ranges from 18.76 K ± 3.16 K to 33.21K ± K and 22.84 K ± 0.18 K to 24.48 K ± 0.63 K. The isolated cavity like structure around the AGB stars has an extension of 45.67 pc × 17.02 pc and 42.25 pc × 17.76 pc, respectively. The core region is found to be edge-on having an inclination angle of 79.46° and 73.99°, respectively.

KAFE: the Key-analysis Automated FITS-images Explorer

We present KAFE—the Key-analysis Automated FITS-images Explorer. KAFE is a web-based FITS image postprocessing analysis tool designed to be applicable in the radio to sub-mm wavelength domain. KAFE was developed to complement selected FITS files with metadata based on a uniform image analysis approach as well as to provide advanced image diagnostic plots. It is ideally suited for data mining purposes and multiwavelength/multi-instrument data samples that require uniform data diagnostic criteria. We present the code structure and interface, the keyword definitions, the products generated for selected users’ science cases, and application examples.

Revisiting the GNSS-R Waveform Statistics and Its Impact on Altimetric Retrievals

This paper analyzes the ocean altimetry precision of global navigation satellite systems’ reflectometry (GNSS-R) by characterizing the noise statistics of the measured waveform. For this purpose, we first investigate the dependence of the altimetry precision on the statistics of the observed waveform and then derive an analytical model of the waveform statistics after incoherent averaging. The main data set used for altimetry analysis and model validation is the GPS L5 signals obtained from an airborne experiment. Two different delay estimators, based on the leading-edge derivative (DER) and the waveform fitting (FIT) over the leading edge, have been implemented. Later, the relationship between the statistics of the observed waveform and the altimetry precision is derived and validated for both the estimators with the airborne data. Then, the analytical model of the statistics of the incoherently averaged waveform is built from the correlation properties of the complex waveform, and also validated with both airborne and the TechDemoSat-1 spaceborne data. After that, the proposed waveform statistics and altimetry precision models are applied to spaceborne cases with different orbit altitudes. The altimetry performance of different onboard processing methods, i.e., conventional GNSS-R and interferometric GNSS-R, and delay estimators, i.e., DER and FIT, are preliminarily assessed. Finally, the dependence of altimetry precision on different parameters is analyzed and a simplified model of altimetry precision is proposed for the spaceborne case.

The Local Volume H i Survey (LVHIS)

The `Local Volume HI Survey' (LVHIS) comprises deep HI spectral line and 20-cm radio continuum observations of 82 nearby, gas-rich galaxies, supplemented by multi-wavelength images. Our sample consists of all galaxies with Local Group velocities v_LG < 550 km/s or distances D < 10 Mpc that are detected in the HI Parkes All Sky Survey (HIPASS). Using full synthesis observations in at least three configurations of the Australia Telescope Compact Array (ATCA), we obtain detailed HI maps for a complete sample of gas-rich galaxies with Dec < -30 deg. Here we present a comprehensive LVHIS Galaxy Atlas, including the overall gas distribution, mean velocity field, velocity dispersion, and position-velocity diagrams, together with a homogeneous set of measured and derived galaxy properties. Our primary goal is to investigate the HI morphologies, kinematics, and environment at high resolution and sensitivity. LVHIS galaxies represent a wide range of morphologies and sizes; our measured HI masses range from ~10^7 to 10^10 Msun, based on independent distance estimates. The LVHIS Galaxy Atlas (including FITS files) is available on-line.

The Galaxy Cluster Merger Catalog: An Online Repository of Mock Observations from Simulated Galaxy Cluster Mergers

Abstract We present the “Galaxy Cluster Merger Catalog.” This catalog provides an extensive suite of mock observations and related data for N-body and hydrodynamical simulations of galaxy cluster mergers and clusters from cosmological simulations. These mock observations consist of projections of a number of important observable quantities in several different wavebands, as well as along different lines of sight through each simulation domain. The web interface to the catalog consists of easily browsable images over epoch and projection direction, as well as download links for the raw data and a JS9 interface for interactive data exploration. The data are presented within a consistent format so that comparison between simulations is straightforward. All of the data products are provided in the standard Flexible Image Transport System file format. The data are being stored on the yt Hub (http://hub.yt), which allows for remote access and analysis using a Jupyter notebook server. Future versions of the catalog will include simulations from a number of research groups and a variety of research topics related to the study of interactions of galaxy clusters with each other and with their member galaxies. The catalog is located at http://gcmc.hub.yt.

Redetection of the Ionospheric Signature of Saturn's “Ring Rain”

AbstractIn April 2011 Saturn's midlatitude ionospheric emissions were detected, exhibiting anomalous (nonsolar) latitudinal variations consistent with the transport of water from specific locations in Saturn's rings, known as “ring rain”. These products, transported to the planet along the magnetic field, may help to explain the unusual pattern of peaks and troughs in electron densities discovered in Saturn's ionosphere by spacecraft flybys. In the present study, we analyzed emissions recorded on 23 April 2013, showing for the first time since the original detection that Saturn's midlatitude emissions are indeed heavily modified. Although the 2013 emissions are dimmer by almost a factor of 3.7, the latitudinal contrast is greater and uncertainties are lower. Increased intensities were found near planetocentric latitudes of 43°, 51°, and 63°, previously identified with sources at the inner edge of the B ring, A ring, and the orbit of Enceladus and associated E ring.