The Balmer decrement of SDSS galaxies

High resolution spectra are necessary to distinguish and correctly measure the Balmer emission lines due to the presence of strong metal and Balmer absorption features in the stellar continuum. This accurate measurement is necessary for use in emission line diagnostics, such as the Balmer decrement (i.e. Halpha/Hbeta), used to determine the attenuation of galaxies. Yet at high redshifts obtaining such spectra becomes costly. Balmer emission line equivalent widths are much easier to measure, requiring only low resolution spectra or even simple narrow band filters and therefore shorter observation times. However a correction for the stellar continuum is still needed for this equivalent width Balmer decrement. We present here a statistical analysis of the Sloan Digital Sky Survey Data Release 7 emission line galaxy sample, using the spectrally determined Balmer emission line fluxes and equivalent widths. Using the large numbers of galaxies available in the SDSS catalogue, we determined an equivalent width Balmer decrement including a statistically-based correction for the stellar continuum. Based on this formula, the attenuation of galaxies can now be obtained from low spectral resolution observations. In addition, this investigation also revealed an error in the Hbeta line fluxes, within the SDSS DR7 MPA/JHU catalogue, with the equivalent widths underestimated by average ~0.35A in the emission line galaxy sample. This error means that Balmer decrement determined attenuations are overestimated by a systematic 0.1 magnitudes in A_V, and future analyses of this sample need to include this correction.Comment: 10 pages, accepted MNRA

The radio properties of optically obscured Spitzer sources

This paper analyses the radio properties of a subsample of optically obscured (R>25.5) galaxies observed at 24um by the Spitzer Space Telescope within the First Look Survey. 96 F[24um]>0.35 mJy objects out of 510 are found to have a radio counterpart at 1.4 GHz, 610 MHz or at both frequencies respectively down to ~40uJy and ~200uJy. IRAC photometry sets the majority of them in the redshift interval z [1-3] and allows for a broad distinction between AGN-dominated galaxies (~47% of the radio-identified sample) and systems powered by intense star-formation (~13%), the remaining objects being impossible to classify. The percentage of radio identifications is a strong function of 24um flux. The radio number counts at both radio frequencies suggest that the physical process(es) responsible for radio activity in these objects have a common origin regardless of whether the source shows mid-IR emission compatible with being an obscured AGN or a star-forming galaxy. We also find that both candidate AGN and star-forming systems follow (although with a large scatter) the relationship between 1.4 GHz and 24um fluxes reported by Appleton et al. (2004) which identifies sources undergoing intense star formation activity. On the other hand, the inferred radio spectral indices alpha indicate that a large fraction of objects in our sample (~60% of all galaxies with estimated alpha) may belong to the population of Ultra Steep Spectrum (USS) Sources, typically 'frustrated' radio-loud AGN. We interpret our findings as a strong indication for concurrent AGN and star-forming activity, whereby the 1.4 GHz flux is of thermal origin, while that at 610 GHz mainly stems from the nuclear source.Comment: 18 pages, 16 figures, to appear in MNRA

Satellite content and quenching of star formation in galaxy groups at z ~ 1.8

We study the properties of satellites in the environment of massive star-forming galaxies at z ~ 1.8 in the COSMOS field, using a sample of 215 galaxies on the main sequence of star formation with an average mass of ~1011M⊙. At z> 1.5, these galaxies typically trace halos of mass ≳1013M⊙. We use optical-near-infrared photometry to estimate stellar masses and star formation rates (SFR) of centrals and satellites down to ~ 6 × 109M⊙. We stack data around 215 central galaxies to statistically detect their satellite halos, finding an average of ~3 galaxies in excess of the background density. We fit the radial profiles of satellites with simple β-models, and compare their integrated properties to model predictions. We find that the total stellar mass of satellites amounts to ~68% of the central galaxy, while spectral energy distribution modeling and far-infrared photometry consistently show their total SFR to be 25-35% of the central's rate. We also see significant variation in the specific SFR of satellites within the halo with, in particular, a sharp decrease at <100 kpc. After considering different potential explanations, we conclude that this is likely an environmental signature of the hot inner halo. This effect can be explained in the first order by a simple free-fall scenario, suggesting that these low-mass environments can shut down star formation in satellites on relatively short timescales of ~0.3 Gyr

Investigating the Far-IR/Radio Correlation of Star Forming Galaxies to z=3

In order to examine the far-IR/radio correlation at high redshift we have studied the Spitzer 70um/far-infrared (far-IR) properties of sub-mJy radio sources from the 13^H XMM-Newton/Chandra Deep Field by redshift and galaxy type: active galactic nucleus (AGN) or star forming galaxy (SFG). We directly detect 70um counterparts (at >3sigma significance) for 22.5% (92/408) of the radio sources, while for the rest we perform stacking analysis by redshift and galaxy type. For the sources detected at 70um we find that the median and scatter of the observed flux density ratio, q70, are similar to previous results in the literature, but with a slight decrease in q70 towards higher redshifts. Of the radio sources detected at 70um 8/92 were already classified as AGN, but two of which maybe SFGs. For the stacked sources we obtain a detection for the SFGs at every redshift bin which implies they have mean flux densities a factor ~5 below the original 70um detection limit. For the stacked AGN we obtain a detection only in our highest redshift bin (1<~z<~5) where we may be sampling hot dust associated with the AGN at rest-frame 12-35um. The combined observed mean value of q70 for the SFGs (detected and non-detected at 70um) decreases gradually with redshift, consistent with tracks derived from empirical spectral energy distributions (SEDs) of local SFGs. Upon closer inspection and when comparing with tracks of appropriate luminosity, the values of q70 broadly agree at low redshift. However, at z~1, the observed q70 (for ULIRGs) is 2sigma below the value seen for local ULIRGs tracks, implying a difference in the SED between local and z~1 ULIRGs. At higher redshifts, the convergence of the tracks and the higher uncertainties in q70 do not allow us to determine if such a difference persists.Comment: 10 pages, 4 figures, accepted for publication in MNRA

SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65 < z < 1.1 galaxies

We report on results from the analysis of a stellar mass-selected (log (M*/M⊙) ≥ 9.0) sample of 1644 galaxies at 0.65 11, in agreement with downsizing scenarios

Dental metric standards for sex estimation in archaeological populations from Iran

Sex estimation of skeletal remains is one of the major components of forensic identification of unknown individuals. Teeth are a potential source of information on sex and are often recovered in archaeological or forensic contexts due to their post-mortem longevity. Currently there is limited data on dental sexual dimorphism of archaeological populations from Iran. This dissertation represents the first study to provide a dental sex estimation method for Iron Age populations. The current study was conducted on the skeletal remains of 143 adults from two Iron Age populations in close temporal and geographic proximity in the Solduz Valley (West Azerbaijan Province of Iran). 2D and 3D cervical mesiodistal and buccolingual and root volume measurements of maxillary and mandibular teeth were used to investigate the degree of sexual dimorphism in permanent dentition and to assess their applicability in sex estimation. In total 1327, 457, and 480 anterior and posterior teeth were used to collect 2D cervical, 3D cervical, and root volume measurements respectively. 2D cervical measurements were taken using Hillson-Fitzgerald dental calliper and 3D measurements were collected using CT images provided by Open Research Scan Archive (ORSA) - Penn Museum. 3D models of the teeth were created using manual segmentation in the Amira 6.01 software package. Since tooth density largely differs from crown to apex, root segmentation required two threshold levels: the segmentation of the root from the jaw and the segmentation of the crown from the root. Thresholds used for root segmentation were calculated using the half maximum height protocol of Spoor et al. (1993) for each skull, and thresholds used for crown segmentation were set visually for each tooth separately. Data was analysed using discriminant function analysis and posterior probabilities were calculated for all produced formulae where sex was previously assessed from morphological features of pelvis and skull. Bootstrapping was used to account for small sample sizes in the analysis. Statistical analysis was carried out using SPSS 23. The percentage of sexual dimorphism was also used to quantify the amount of sexual dimorphism in the sample. The results showed that incisors and canines were the most sexually dimorphic teeth, providing percentages of correct sex classification between 80% and 100% depending on the measurement used. Root volume measurement was shown to be the most sexually dimorphic variable providing an accuracy of over 90% in all functions. The present study provided the first dental metric standards for sex estimation using odontometric data in Iranian archaeological populations. Dental measurements, particularly root volume measurements, were found to be of value for sex assessment and the method presented here could be a useful tool for establishing accurate demographic data from skeletal remains of the Iron Age from Iran

Association of socioeconomic status with overall overweight and central obesity in men and women: the French Nutrition and Health Survey 2006

<p>Abstract</p> <p>Background</p> <p>Identification of subpopulations at high risk of overweight and obesity is crucial for prevention and management of obesity in different socioeconomic status (SES) categories. The objective of the study was to describe disparities in the prevalence of overweight and obesity across socioeconomic status (SES) groups in 18–74 year-old French adults.</p> <p>Methods</p> <p>Analyses were based on a multistage stratified random sample of non-institutionalized adults aged 18–74-years-old from the French Nutrition and Health Survey (ENNS), a cross-sectional national survey carried out in 2006/2007. Collected data included measured anthropometry (weight, height and waist circumference (WC)), demographic and SES data (occupation, education and frequency of holiday trips as a marker of family income). SES factors associated with overweight (BMI ≥ 25) and central obesity (WC above gender-specific references) were identified using multiple logistic regression.</p> <p>Results</p> <p>Almost half (49.3%) of French adults were overweight or obese and 16.9% were obese. In men, the risk of overall overweight or obesity was associated with occupation (p < 0.05), whereas the risk of central obesity was independently associated with occupation (p < 0.05) and frequency of holiday trips (p < 0.01). In women, both overall and central overweight and obesity were independently associated with educational level (respectively p < 10^-3and p < 10^-3) and frequency of holiday trips (respectively p < 0.05 and p < 10^-3).</p> <p>Conclusion</p> <p>The prevalence of overweight and obesity was found to be similar to that of several neighbouring western European countries, and lower than the UK and eastern Europe. Risk of being overweight or obese varied across SES groups both in men and women, but associations were different between men and women, indicating differing determinants.</p

Children’s residential exposure to selected allergens and microbial indicators: endotoxins and (1→3)-β-D-glucans

Objectives: The study was aimed at assessment of exposure to endotoxins, (1→3)-β-D-glucans and mite, cockroach, cat, dog allergens present in settled dust in premises of children as agents which may be significantly correlated with the occurrence of allergic symptoms and diseases in children. Materials and Methods: The study covered 50 homes of one- or two-year-old children in Poland. Samples of settled dust were taken from the floor and the child's bed. The levels of (1→3)-β-D-glucans (floor), endotoxins (floor) and allergens of mite, cat, dog and cockroach (floor and bed) were analyzed. Results: Average geometric concentrations (geometric standard deviation) of endotoxins, (1→3)-β-D-glucans, Der p1, Fel d1, Can f1 and Bla g1 in children homes were on the floor 42 166.0 EU/g (3.2), 20 478.4 ng/g (2.38), 93.9 ng/g (6.58), 119.8 ng/g (13.0), 288.9 ng/g (3.4), 0.72 U/g (4.4) and in their beds (only allergens) 597.8 ng/g (14.2), 54.1 ng/g (4.4), 158.6 ng/g (3.1) 0.6 U/g (2.9), respectively. When the floor was covered with the carpet, higher concentrations of endotoxins, (1→3)-β-D-glucans and allergens (each type) were found in the settled dust (p < 0.05). The trend was opposite in case of allergens (except dog) analyzed from bed dust and significantly higher concentrations were found in the rooms with smooth floor (p < 0.05). Conclusions: Among the analyzed factors only the type of floor significantly modified both the level of biological indicators and allergens. The results of this study could be the base for verifying a hypothesis that carpeting may have a protective role against high levels of cockroach, dog and cat allergens