We perform a spectroscopic survey of the foreground population in Orion. A with MMT/Hectospec. We use these data, along with archival spectroscopic data and photometric data, to derive spectral types, extinction values, and masses for 691 stars. Using the Spitzer Space Telescope data, we characterize the disk properties of these sources. We identify 37 new transition disk (TD) objects, 1 globally depleted disk candidate, and 7 probable young debris disks. We discover an object with a mass of. less than 0.018-0.030 M-circle dot, which harbors a flaring disk. Using the Ha emission line, we characterize the accretion activity of the sources with disks, and confirm that the. fraction of accreting TDs is lower than that of optically thick disks (46% +/- 7% versus 73% +/- 9%, respectively). Using kinematic data from the Sloan Digital Sky Survey and APOGEE INfrared Spectroscopy of the Young Nebulous Clusters program (IN-SYNC), we confirm that the foreground population shows similar kinematics to their local molecular clouds and other young stars in the same regions. Using the isochronal ages, we find that the foreground population has a median age of. around 1-2 Myr, which is similar to that of other young stars in Orion. A. Therefore, our results argue against the presence of a large and old foreground cluster in front of Orion. A.

Recent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been recognized as a member of this "iron-complex" cluster class, and we provide here a chemical and kinematic analysis of > 300 red giant branch and asymptotic giant branch member stars using high-resolution spectra obtained with the Magellan-M2FS and VLT-FLAMES instruments. Multiple lines of evidence indicate that NGC 6273 possesses an intrinsic metallicity spread that ranges from about [Fe/H] = -2 to -1 dex, and may include at least three populations with different [Fe/H] values. The three populations identified here contain separate first (Na/Al-poor) and second (Na/Al-rich) generation stars, but a Mg-Al anti-correlation may only be present in stars with [Fe/H] greater than or similar to -1.65. The strong correlation between [La/Eu] and [Fe/H] suggests that the sprocess must have dominated the heavy element enrichment at higher metallicities. A small group of stars with low [alpha/Fe] is identified and may have been accreted from a former surrounding field star population. The cluster's large abundance variations are coupled with a complex, extended, and multimodal blue horizontal branch (HB). The HB morphology and chemical abundances suggest that NGC 6273 may have an origin that is similar to omega Cen and M54.

We present the results of a new spectroscopic survey for dusty intervening absorption systems, particularly damped Ly alpha absorbers (DLAs), toward reddened quasars. The candidate quasars are selected from mid-infrared photometry from the Wide-field Infrared Survey Explorer combined with optical and near-infrared photometry. Out of 1073 candidates, we secure low-resolution spectra for 108 using the Nordic Optical Telescope on La Palma, Spain. Based on the spectra, we are able to classify 100 of the 108 targets as quasars. A large fraction (50%) is observed to have broad absorption lines (BALs). Moreover, we find six quasars with strange breaks in their spectra, which are not consistent with regular dust reddening. Using template fitting, we infer the amount of reddening along each line of sight ranging from A(V). approximate to. 0.1 to 1.2 mag (assuming a Small Magellanic Cloud extinction curve). In four cases, the reddening is consistent with dust exhibiting the 2175 angstrom feature caused by an intervening absorber, and for two of these, an Mg II absorption system is observed at the best-fit absorption redshift. In the rest of the cases, the reddening is most likely intrinsic to the quasar. We observe no evidence for dusty DLAs in this survey. However, the large fraction of BAL quasars hampers the detection of absorption systems. Out of the 50 non-BAL quasars, only 28 have sufficiently high redshift to detect Ly alpha in absorption.

We present new spatially resolved surface photometry in the far-ultraviolet (FUV) and near-ultraviolet (NUV) from images obtained by the Galaxy Evolution Explorer (GALEX) and IRAC1 (3.6 mu m) photometry from the Spitzer Survey of Stellar Structure in Galaxies (S(4)G). We analyze the radial surface brightness profiles mu(FUV), mu(NUV), and mu[3.6], as well as the radial profiles of (FUV - NUV), (NUV -[3.6]), and (FUV -[3.6]) colors in 1931 nearby galaxies (z < 0.01). The analysis of the 3.6 mu m surface brightness profiles also allows us to separate the bulge and disk components in a quasi-automatic way and to compare their light and color distribution with those predicted by the chemo-spectrophotometric models for the evolution of galaxy disks of Boissier & Prantzos. The exponential disk component is best isolated by setting an inner radial cutoff and an upper surface brightness limit in stellar mass surface density. The best-fitting models to the measured scale length and central surface brightness values yield distributions of spin and circular velocity within a factor of two of those obtained via direct kinematic measurements. We find that at a surface brightness fainter than mu([3.6]) = 20.89 mag arcsec(-2), or below 3 x 10(8) M-circle dot kpc(-2) in stellar mass surface density, the average specific star formation rate (sSFR) for star-forming and quiescent galaxies remains relatively flat with radius. However, a large fraction of GALEX Green Valley galaxies show a radial decrease in sSFR. This behavior suggests that an outside-in damping mechanism, possibly related to environmental effects, could be testimony of an early evolution of galaxies from the blue sequence of star-forming galaxies toward the red sequence of quiescent galaxies.

Outbursts on young stars are usually interpreted as accretion bursts caused by instabilities in the disk or the star-disk connection. However, some protostellar outbursts may not fit into this framework. In this paper, we analyze optical and near-infrared spectra and photometry to characterize the 2015 outburst of the probable young star ASASSN-15qi. The similar to 3.5mag brightening in the V band was sudden, with an unresolved rise time of less than one day. The outburst decayed exponentially by 1mag for 6. days and then gradually back to the pre-outburst level after 200 days. The outburst is dominated by emission from similar to 10,000K gas. An explosive release of energy accelerated matter from the star in all directions, seen in a spectacular cool, spherical wind with a maximum velocity of 1000 km s(-1). The wind and hot gas both disappeared as the outburst faded and the source returned to its quiescent F-star spectrum. Nebulosity near the star brightened with a delay of 10-20 days. Fluorescent excitation of H-2 is detected in emission from vibrational levels as high as v = 11, also with a possible time delay in flux increase. The mid-infrared spectral energy distribution does not indicate the presence of warm dust emission, though the optical photospheric absorption and CO overtone emission could be related to a gaseous disk. Archival photometry reveals a prior outburst in 1976. Although we speculate about possible causes for this outburst, none of the explanations are compelling.

Purpose: The purpose of this paper is to examine how material, vital for the designprocess (supporting documents) is handled throughout the entire process. From obtaining the material from the document-administer until the material is transformed and applicable in a BIM-software in the design-process. Method: The first method is a case study that contains semi-structured interviews with one large as well as one small design-firm in Sweden, but also the biggest client regarding infrastructure in Sweden. Secondly, the other part of this thesis work is to perform an experiment containing two parts where the first one is to examine supporting material of an ongoing infrastructure-project and evaluate the quality, as well as constructing conversion rules to evaluate how supporting documents can be implemented. Findings: All the respondents in the conducted survey reported that supporting material regarding electric-, telecommunication- and fibre-optic cables were supporting material with the lowest degree of accuracy. Furthermore, the most used file-format is DWG, but file-formats like PDF, JPG, XML and LAS are also file-formats that is used according to the respondents. All the respondents suggest that a standardised way of using supporting documents would be an efficient way of standardising the process. The findings from the experiment concluded that the most used file-format used as supporting material is DWG (79%), followed by PDF (21 %). The quality varied between different providers. Supporting material provided straight from the contractor in DWG had great or excellent quality. Material as PDF/JPG needed to be processed in order to be used in a BIM-software. The implementing of conversion rules resulted in way of implementing these. In order to use this, the supporting document needs to be digital, in this case as DWG-files. Well established ways of using colours, layers and names in the CAD-software is vital. Implications: In order to make the way of handling the supporting material more efficient, a standardised way of handling these need to be used, as well as standardised file-formats. By making the supporting material digital, this will make the material more accessible, thus is the quality of e.g. PDF and JPG “not sufficient” because a BIMuser must convert these files manually, which provide one source of error. Therefore, these files lack interoperability. Regarding the material provided by the contractor, the design-firm need to have direct communication with the provider of the supporting material to take advantage of DWG-files and use the same file-formats, layers etc., to reduce the time it takes to convert the supporting documents manually. Limitations: A limitation is that only one large and one small design-firm is analysed. One part of a complete BIM-software is used, so the external validity is low, because the result may only be used in another small design-firm with the same project configurations and programmes. The experiment, where Conversion Rules were examined did only embrace wells (water-systems). / Syfte: Syftet med detta examensarbete är att ta reda på hur underlagshanteringen ser ut igenom hela processen från tillhandahållning av underlaget till implementering i projekteringsprocessen. Metod: Den första är en fallstudie som består av kvalitativa semi-strukturerade intervjuer med en stor och en liten konsultfirma inom projekteringsprocessen, såväl som den största beställaren av infrastrukturprojekt i Sverige. Den andra delen är ett experiment som är uppdelat i två delar där den första är att ta reda på hur underlag ser ut och bedöma dessa i ett pågående infrastrukturprojekt. Den andra delen är att upprätta så kallade konverteringsregler för att importera underlag i en BIM-mjukvara. Resultat: Samtliga respondenter i intervjuerna svarade att underlag gällande el-, teleoch fiberoptikkablar är underlag med lägst grad av träffsäkerhet/noggrannhet. Vidare svarade respondenterna att DWG är filformatet som oftast används. Andra filformat som PDF, JPG, XML och LAS är även det filformat som används. Samtliga respondenter redogjorde även för vissa åtgärder som kan vidtas för att standardisera underlagshantering i branschen. Däribland efterfrågas en standardisering av underlagshantering gällande lagernamn, färger, filformat osv. I experimentet visade det sig att underlag i DWG-format svarar för (79 %) av underlagen, följt av PDF (21 %). Kvaliteten varierade mellan olika källor, där underlag tillhandahållna direkt av entreprenören i DWG hade bra eller utomordentlig kvalitet. Underlag i from av PDF/JPG måste omvandlas för hand för att kunna används i en BIM-mjukvara. Implementeringen av konverteringsregler resulterade i en arbetsgång för att implementera konverteringsregler i projekteringsprocessen. För att göra detta krävs underlag i DWG-format. Konsekvenser: För att göra underlagshanteringsprocessen mer effektiv, behövs ett standardiserat sätt att använda dessa, såväl som filformat. Genom att digitalisera underlag bidrar detta till att höja antagningsgraden i CAD- och BIM-mjukvaror. Således är kvalitén av exempelvis PDF och JPG ”inte tillräckligt” på grund av att en person manuellt måste omvandla dessa filer, som bidrar till en felkälla. Därav är interoperabiliteten bristfällig. Gällande material tillhandahållen av entreprenören, så måste en god kommunikation upprättas mellan de båda parterna för att dra nytta av underlag i DWG, och använda samma filformat, lager etcetera, för att reducera tidsåtgången i att konvertera exempelvis PDF-filer manuellt. Begränsningar: Endast en stor och en lite konsultfirma analyseras. Endast en del av en komplett BIM-mjukvara används, därav låg extern validitet, då resultatet endast kan appliceras i en annan liten konsultfirma med samma projekt-konfigurationer och program. I experimentet där konverteringsregler utreddes inkluderades endast brunnar (VA).

Electric and magnetic fields in the vicinity of strong sources of radiation (e.g. radar and broadcasting) can exceed the limits mentioned in the national standards for the exposition of persons. Field probes are needed to warn personnel if they are going too close to the RF-sources. For acceptance reasons the field probes should be universal in such a way that no user adjustment of frequency is required. The limits for power density, electric and magnetic field strength depend on the frequency. In contrast, field probes covering a large frequency range, e.g. 1 MHz to 18 GHz or even larger, normally have a flat frequency response. Therefore, the person using the field probe has to know the frequency of the electromagnetic field and to evaluate fieldstrength with respect to the frequency dependent limit value defined by law. Human mistakes while making that evaluation can lead to expositions above the limit value. On the other hand, the evaluation of the power density in the presence of multiple strong sources of radiation at different frequencies with different limit values also leads to measurement problems. A new approach has been undertaken to overcome these difficulties in the development of a rectifying field probe. It consists in shaping the antenna factor of the probe inversely proportional to the limit value. The isotropic response of field probes can be achieved, if three dipole antennas are arranged perpendicular to each other. The presence of dielectric supporting material leads to degradation of the isotropic response of such a field probe. The effect will be investigated. For typical substrates the isotropic response is degraded by up to 3.8 dB. An compensation for this effect will be proposed that leads to a residual unisotropic response of less than 0.2 dB.

Electric and magnetic fields in the vicinity of strong sources of radiation (e.g. radar and broadcasting) can exceed the limits mentioned in the national standards for the exposition of persons. Field probes are needed to warn personnel if they are going too close to the RF-sources. For acceptance reasons the field probes should be universal in such a way that no user adjustment of frequency is required. The limits for power density, electric and magnetic field strength depend on the frequency. In contrast, field probes covering a large frequency range, e.g. 1 MHz to 18 GHz or even larger, normally have a flat frequency response. Therefore, the person using the field probe has to know the frequency of the electromagnetic field and to evaluate fieldstrength with respect to the frequency dependent limit value defined by law. Human mistakes while making that evaluation can lead to expositions above the limit value. On the other hand, the evaluation of the power density in the presence of multiple strong sources of radiation at different frequencies with different limit values also leads to measurement problems. A new approach has been undertaken to overcome these difficulties in the development of a rectifying field probe. It consists in shaping the antenna factor of the probe inversely proportional to the limit value. The isotropic response of field probes can be achieved, if three dipole antennas are arranged perpendicular to each other. The presence of dielectric supporting material leads to degradation of the isotropic response of such a field probe. The effect will be investigated. For typical substrates the isotropic response is degraded by up to 3.8 dB. An compensation for this effect will be proposed that leads to a residual unisotropic response of less than 0.2 dB.