Low resolution spectroscopy of ISOGAL sources: Search for early-type stars with infrared excess

An analysis of low resolution spectra and infared data of 29 ISOGAL-DENIS sources with mid-IR excess is presented. Eight ISOGAL sources from our sample with 7-15 micron excess are found to be B and A-type stars, some of them with emission lines. Two ISOGAL sources, J175614.4-240831 (B3-4IIIe) and J173845.3-312403 (B7III), show a bump between 5000 and 6000 Angstroem which maybe attributed to extended red emission (ERE). Some of the B,A and F-type giants with a large infrared excess might be in the post-AGB phase. For about 50% of the sources in this preliminary study, a nearby second (or even multiple) component was found. Such sources, in particular two B-stars, are not discussed when the probability of the optical spectrum being associated with the ISOGAL source is low. These results confirm that the DENIS-ISOGAL I-J/K-[15] diagram is the most suitable diagram to distinguish between early (AB) and late spectral types (KM). It provides the most useful tool to systematically search for nearby early-type stars with an infrared excess among the background of distant AGB stars in ISOGAL fields of the Galactic disk

New infrared carbon stars in the IRAS point source catalog

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

A comparison of two methods of heart rate variability assessment at high altitude.

Heart rate variability (HRV) is a useful index of autonomic function and has been linked to the development of high altitude (HA) related illness. However, its assessment at HA has been undermined by the relative expense and limited portability of traditional HRV devices which have mandated at least a minute heart rate recording. In this study, the portable ithlete(™) HRV system, which uses a 55 s recording, was compared with a reference method of HRV which utilizes a 5 min electrocardiograph recording (CheckMyHeart(™) ). The root mean squares of successive R-R intervals (RMSSD) for each device was converted to a validated HRV score (lnRMSSD × 20) for comparison. Twelve healthy volunteers were assessed for HRV using the two devices across seven time points at HA over 10 days. There was no significant change in the HRV values with either the ithlete (P = 0·3) or the CheckMyHeart(™) (P = 0·19) device over the seven altitudes. There was also a strong overall correlation between the ithlete(™) and CheckMyHeart(™) device (r = 0·86; 95% confidence interval: 0·79-0·91). The HRV was consistently, though non-significantly higher with ithlete(™) than with the CheckMyHeart(™) device [mean difference (bias) 1·8 l; 95% CI -12·3 to 8·5]. In summary, the ithlete(™) and CheckMyHeart(™) system provide relatively similar results with good overall agreement at HA

Automatic updating of histograms in MySQL

Når en spørring blir optimalisert av spørreoptimalisatoren i en database er det mange faktorer som undersøkes før valg av spørreplan blir tatt. En av disse er rekkefølgen tabeller joines i. Rekkefølgen bestemmes i stor grad av kardinaliteten til tabllen. Dersom noen av predikatene kan benyttes til å filtere vekk rader i tabellene før join operasjonen begynner, vil det redusere kjøretiden. Dermed blir dette nesten alltid gjort. Selektiviteten til predikatene blir bestemt av antall rader i tabellen som tilfredstiller predikatet. Dette approksimeres enten ved hjelp av et histogram eller ved bruk av heuristikker. Heuristikker er kontstante verdier som blir bestemt av de som utvikler spørreoptimalisatoren. Disse gir sjelden et like nøyaktig estimat som et histogram. Det er dog slik at et histogram må beregnes, noe som tar opp tid og ressurser. Dersom dataen histogrammet er basert på endres uten at histogramet beregnes på nytt, vil histogrammet være feil og gi et unøyaktig selektivitets estimat. Effekten varierende histogram nøyaktighet og forskjellige oppdaterings startegier for histogram har på kjøretiden til spørringer evalueres i denne rapporten. Sammen med design av kravene til ,og implementeringen av, en database hvor histogram nøyaktighet har en effekt på kjørtiden til spørringer. Til å begynne med presenteres ni forskjellige oppdateringsmetoder hvorav fire implementeres. Senere presenteres fire nye som basis for fremtidig arbeid. Gjennom testing av de implementerte oppdaterings metodene og en gruppe med base metoder, vises det at i den gitte databasen yter unøyaktige histogram dårligere enn nøyaktige histogram, og også verre enn ingen histogram. Det vises videre at gjennom relativt enkle oppdaterings metoder kan ytelsen til databasen økes betraktelig sammenlignet med unøyaktige histogram. Det vises og at oppdaterings metodene som benyttes i to moderne system yter dårlig i vår database

Total solar eclipse 2017 in USA: deep coronal spectra

International audienc

New deep coronal spectra from the 2017 total solar eclipse

International audienceContext. The origin of the high temperature of the solar corona, in both the inner bright parts and the more outer parts showing flows toward the solar wind, is not understood well yet. Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum white-light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona), and the dust component with F-lines (F-corona).Aims. By sufficiently dispersing the W-L spectrum, the Fraunhofer (F) spectrum of the dust component of the corona appears and the continuum Thomson radiation can be evaluated. The superposed emission lines of ions with different degrees of ionization are studied to allow the measurement of temperatures, non-thermal velocities, Doppler shifts, and abundances to constrain the proposed heating mechanisms and understand the origin of flows that lead to solar wind.Methods. We describe a slit spectroscopic experiment of high spectral resolution to provide an analysis of the most typical parts of the quasi-minimum type corona observed during the total solar eclipse of Aug. 21, 2017 from Idaho, USA. Streamers, active region enhancements, and polar coronal holes (CHs) are measured well using deep spectra.Results. Sixty spectra are obtained during the totality with a long slit, covering ±3 solar radii in the range of 510 nm to 590 nm. The K+F continuum corona is exposed well up to two solar radii. The F-corona can be measured even at the solar limb. New weak emission lines were discovered or confirmed. The rarely observed Ar X line is detected almost everywhere; the Fe XIV and Ni XIII lines are clearly detected everywhere. For the first time hot lines are also measured inside the CH regions. The radial variations of the non-thermal turbulent velocities of the lines do not show a great departure from the average values. No significantly large Doppler shifts are seen anywhere in the inner or the middle corona. The wings of the Fe XIV line show some non-Gaussianity.Conclusions. Deep slit coronal spectra offered an opportunity for diagnosing several aspects of coronal physics during a well observed total eclipse without extended investments. The analysis of the ionic emission line profiles offers several powerful diagnostics of the coronal dynamics; the precise measurement of the F-continuum component provides insight into the ubiquitous dust corona at the solar limb