A comparison of the socio-cultural influences on body size perceptions and values among European Australian and Indigenous Fijian adolescent girls

Western women are experiencing increases in the prevalence of overweight and obesity despite valuing slimness as ideal and equating thinness with attractiveness and beauty. Pacific populations are also experiencing high prevalence rates of overweight and obesity. A lage body size, however, has many positive connotations among pacific populations that stem from rich cultural practices such as feasts and deliberate fattening of women. There appears to be many sociocultural factors however, such as images of the slim ideal portrayed in Western media, influencing body image concerns that are shared between the two groups. A qualitative study involving semi-structured interviews was conducted to examine and compare the sociocultural influences on body size perceptionsand values. Participants include 16 European Australian and 16 Indigenous Fijian adolescent girls aged between 15 and 17 years. Inductive thematic analysis and analytical induction were qualitativemethods employed to facilitate interpretation of the findings. Preliminary findings suggest that Fijian adolescent girls experience greater conflict than European Australian girls about the desired body size endorsed in their community. Results also suggest that Indigenous Fijian girls place less importance than Australian girls on manipulating their body to achieve a specific ideal. Specific results of this study are reviewed and recommendations for future research are discussed

Bending properties in oxidized porous silicon waveguides

The greatest limit in high-speed communications between different circuit blocks is due to the delays introduced by metal interconnections. Knock-down wire communication bottleneck is, therefore, one of the best goals that current research could reach in the held of fast electronics. A possible solution is to build fast optical links and even better if the technology is based on silicon. To attain these ends, we have made studies into possibility to fabricate optical waveguide based on oxidized porous silicon. In the last few years, such a device: was realized and characterized. Waveguiding in the visible and in the near infrared was demonstrated, With propagation losses of about 3-5 dB/cm for a light with a wavelength of 632.8 nm. Moreover, a design feature of an integrated waveguide based on oxidized porous silicon is that it offers a spontaneous bending of the waveguiding layer at its ends. The edge bending is provided by a convex camber of a leading edge of forming porous silicon. This bending can be exploited to promote a vertical light output with no use of any additional devices. The paper discusses the properties of edge bending, evaluation of the light losses depending on the radius of curvature, and analysis of possibilities to reduce these losses. (C) 2001 Elsevier Science Ltd. All rights reserved

MIUSCAT: extended MILES spectral coverage. I. Stellar populations synthesis models

We extend the spectral range of our stellar population synthesis models based on the MILES and CaT empirical stellar spectral libraries. For this purpose we combine these two libraries with the Indo-U.S. to construct composite stellar spectra to feed our models. The spectral energy distributions (SEDs) computed with these models and the originally published models are combined to construct composite SEDs for single-age, single-metallicity stellar populations (SSPs) covering the range 3465 - 9469\AA at moderately high, and uniform, resolution (FWHM=2.51\AA). The colours derived from these SSP SEDs provide good fits to Galactic globular cluster data. We find that the colours involving redder filters are very sensitive to the IMF, as well as a number of features and molecular bands throughout the spectra. To illustrate the potential use of these models we focus on the NaI doublet at 8200 \AA and with the aid of the newly synthesized SSP model SEDs we define a new IMF-sensitive index that is based on this feature, which overcomes various limitations from previous index definitions for low velocity dispersion stellar systems. We propose an index-index diagram based on this feature and the neighboring CaII triplet at 8600 \AA, to constrain the IMF if the age and [Na/Fe] abundance are known. Finally we also show a survey-oriented spectrophotometric application which evidences the accurate flux calibration of these models for carrying out reliable spectral fitting techniques. These models are available through our user-friendly website.Comment: 16 pages, 17 figures, 2 tables; MNRAS in press. Model predictions available at our website: http://miles.iac.e

Body image, body dissatisfaction and weight status in south asian children: a cross-sectional study

Background Childhood obesity is a continuing problem in the UK and South Asian children represent a group that are particularly vulnerable to its health consequences. The relationship between body dissatisfaction and obesity is well documented in older children and adults, but is less clear in young children, particularly South Asians. A better understanding of this relationship in young South Asian children will inform the design and delivery of obesity intervention programmes. The aim of this study is to describe body image size perception and dissatisfaction, and their relationship to weight status in primary school aged UK South Asian children. Methods Objective measures of height and weight were undertaken on 574 predominantly South Asian children aged 5-7 (296 boys and 278 girls). BMI z-scores, and weight status (underweight, healthy weight, overweight or obese) were calculated based on the UK 1990 BMI reference charts. Figure rating scales were used to assess perceived body image size (asking children to identify their perceived body size) and dissatisfaction (difference between perceived current and ideal body size). The relationship between these and weight status were examined using multivariate analyses. Results Perceived body image size was positively associated with weight status (partial regression coefficient for overweight/obese vs. non-overweight/obese was 0.63 (95% CI 0.26-0.99) and for BMI z-score was 0.21 (95% CI 0.10-0.31), adjusted for sex, age and ethnicity). Body dissatisfaction was also associated with weight status, with overweight and obese children more likely to select thinner ideal body size than healthy weight children (adjusted partial regression coefficient for overweight/obese vs. non-overweight/obese was 1.47 (95% CI 0.99-1.96) and for BMI z-score was 0.54 (95% CI 0.40-0.67)). Conclusions Awareness of body image size and increasing body dissatisfaction with higher weight status is established at a young age in this population. This needs to be considered when designing interventions to reduce obesity in young children, in terms of both benefits and harms

Extreme emission-line galaxies out to z∼\sim1 in zCOSMOS. I. Sample and characterization of global properties

We present a thorough characterization of a large sample of 183 extreme emission-line galaxies (EELGs) at redshift 0.11 < z < 0.93 selected from the 20k zCOSMOS Bright Survey because of their unusually large emission line equivalent widths. We use multiwavelength COSMOS photometry, HST-ACS I-band imaging and optical zCOSMOS spectroscopy to derive the main global properties of EELGs, such as sizes, masses, SFRs, reliable metallicities from both "direct" and "strong-line" methods. The EELGs are compact (R_50 ~ 1.3 kpc), low-mass (log(M*/Msol)~7-10) galaxies forming stars at unusually high specific SFR (log(sSFR/yr) up to ~ -7) compared to main sequence SFGs of the same stellar mass and redshift. At UV wavelengths, the EELGs are luminous and show high surface brightness and include strong Ly$\alpha$ emitters, as revealed by GALEX spectroscopy. We show that zCOSMOS EELGs are high-ionization, low-metallicity systems, with median 12+log(O/H)=8.16, including a handful of extremely metal-deficient galaxies (<10% solar). While ~80% of the EELGs show non-axisymmetric morphologies, including clumpy and tadpole galaxies, we find that ~29% of them show additional low surface-brightness features, which strongly suggest recent or ongoing interactions. As star-forming dwarfs in the local Universe, EELGs are most often found in relative isolation. While only very few EELGs belong to compact groups, almost one third of them are found in spectroscopically confirmed loose pairs or triplets. We conclude that EELGs are galaxies caught in a transient and probably early period of their evolution, where they are efficiently building-up a significant fraction of their present-day stellar mass in an ongoing galaxy-wide starburst. Therefore, the EELGs constitute an ideal benchmark for comparison studies between low- and high-redshift low-mass star-forming galaxies.Comment: Accepted in A&A. Final replacement to match the version in press. It includes a minor change in the title and a new figur

The zCOSMOS redshift survey: how group environment alters global downsizing trends

Context. Groups of galaxies are a common environment, bridging the gap between starforming field galaxies and quiescent cluster galaxies. Within groups secular processes could be at play, contributing to the observed strong decrease of star formation with cosmic time in the global galaxy population. Aims. We took advantage of the wealth of information provided by the first ~10 000 galaxies of the zCOSMOS-bright survey and its group catalogue to study in detail the complex interplay between group environment and galaxy properties. Methods. The classical indicator F_(blue), i.e., the fraction of blue galaxies, proved to be a simple but powerful diagnostic tool. We studied its variation for different luminosity and mass selected galaxy samples, divided as to define groups/field/isolated galaxy subsamples. Results. Using rest-frame evolving B-band volume-limited samples, the groups galaxy population exhibits significant blueing as redshift increases, but maintains a systematic difference (a lower F_(blue)) with respect to the global galaxy population, and an even larger difference with respect to the isolated galaxy population. However moving to mass selected samples it becomes apparent that such differences are largely due to the biased view imposed by the B-band luminosity selection, being driven by the population of lower mass, bright blue galaxies for which we miss the redder, equally low mass, counterparts. By carefully focusing the analysis on narrow mass bins such that mass segregation becomes negligible we find that only for the lowest mass bin explored, i.e., log(M_*/M_☉) ≤ 10.6, does a significant residual difference in color remain as a function of environment, while this difference becomes negligible toward higher masses. Conclusions. Our results indicate that red galaxies of mass log(M_*/M_☉) ≥ 10.8 are already in place at z ~ 1 and do not exhibit any strong environmental dependence, possibly originating from so-called nature or internal mechanisms. In contrast, for lower galaxy masses and redshifts lower than z ~ 1, we observe the emergence in groups of a population of nurture red galaxies: slightly deviating from the trend of the downsizing scenario followed by the global galaxy population, and more so with cosmic time. These galaxies exhibit signatures of group-related secular physical mechanisms directly influencing galaxy evolution. Our analysis implies that these mechanisms begin to significantly influence galaxy evolution after z ~ 1, a redshift corresponding to the emergence of structures in which these mechanisms take place

The zCOSMOS 10k-sample: the role of galaxy stellar mass in the colour-density relation up to z=1

[Abridged] With the first 10000 spectra of the flux limited zCOSMOS sample (I<=22.5) we study the evolution of environmental effects on galaxy properties since z=1.0, and disentangle the dependence among galaxy colour, stellar mass and local density (3D local density contrast `delta', computed with the 5th nearest neighbour approach). We confirm that within a luminosity-limited sample (M_B=1) galaxies 'f_red' depends on delta at least up to z=1, with red galaxies residing mainly in high densities. This trend weakens for increasing z, and it is mirrored by the behaviour of the fraction of galaxies with D4000A break >=1.4. We also find that up to z=1 the fraction of galaxies with log(EW[OII]) >=1.15 is higher for lower delta, and also this dependence weakens for increasing z. Given the triple dependence among galaxy colours, stellar mass and delta, the colour-delta relation found in the luminosity-selected sample can be due to the broad range of stellar masses. Thus, we fix the stellar mass and we find that in this case the colour-delta relation is flat up to z=1 for galaxies with log(M/M_sun)>=10.7. This means that for these masses the colour-delta relation found in a luminosity-selected sample is the result of the combined colour-mass and mass-delta relations. In contrast, we find that for 0.1<=z<=0.5 and log(M/M_sun)<=10.7 'f_red' depends on delta even at fixed mass. In these mass and z ranges, environment affects directly also galaxy colours. We suggest a scenario in which the colour depends primarily on stellar mass, but for relatively low mass galaxies the local density modulates this dependence. These galaxies formed more recently, in an epoch when evolved structures were already in place, and their longer SFH allowed environment-driven physical processes to operate during longer periods of time.Comment: 19 pages, 12 figures, submitted to A&A, revised version after referee comment

The zCOSMOS redshift survey : Influence of luminosity, mass and environment on the galaxy merger rate

The contribution of major mergers to galaxy mass assembly along cosmic time is an important ingredient to the galaxy evolution scenario. We aim to measure the evolution of the merger rate for both luminosity/mass selected galaxy samples and investigate its dependence with the local environment. We use a sample of 10644 spectroscopically observed galaxies from the zCOSMOS redshift survey to identify pairs of galaxies destined to merge, using only pairs for which the velocity difference and projected separation of both components with a confirmed spectroscopic redshift indicate a high probability of merging. We have identified 263 spectroscopically confirmed pairs with r_p^{max} = 100 h^{-1} kpc. We find that the density of mergers depends on luminosity/mass, being higher for fainter/less massive galaxies, while the number of mergers a galaxy will experience does not depends significantly on its intrinsic luminosity but rather on its stellar mass. We find that the pair fraction and merger rate increase with local galaxy density, a property observed up to redshift z=1. We find that the dependence of the merger rate on the luminosity or mass of galaxies is already present up to redshifts z=1, and that the evolution of the volumetric merger rate of bright (massive) galaxies is relatively flat with redshift with a mean value of 3*10^{-4} (8*10^{-5} respectively) mergers h^3 Mpc^{-3} Gyr^{-1}. The dependence of the merger rate with environment indicates that dense environments favors major merger events as can be expected from the hierarchical scenario. The environment therefore has a direct impact in shapping-up the mass function and its evolution therefore plays an important role on the mass growth of galaxies along cosmic time.Comment: submitted to A&A, 17 pages, 12 figure

K+a galaxies in the zCOSMOS Survey: Physical properties of systems in their post-starburst phase

The identities of the main processes triggering and quenching star-formation in galaxies remain unclear. A key stage in evolution, however, appears to be represented by post-starburst galaxies. To investigate their impact on galaxy evolution, we initiated a multiwavelength study of galaxies with k+a spectral features in the COSMOS field. We examine a mass-selected sample of k+a galaxies at z=0.48-1.2 using the spectroscopic zCOSMOS sample. K+a galaxies occupy the brightest tail of the luminosity distribution. They are as massive as quiescent galaxies and populate the green valley in the colour versus luminosity (or stellar mass) distribution. A small percentage (<8%) of these galaxies have radio and/or X-ray counterparts (implying an upper limit to the SFR of ~8Msun/yr). Over the entire redshift range explored, the class of k+a galaxies is morphologically a heterogeneous population with a similar incidence of bulge-dominated and disky galaxies. This distribution does not vary with the strength of the Hdelta absorption line but instead with stellar mass in a way reminiscent of the well-known mass-morphology relation. Although k+a galaxies are also found in underdense regions, they appear to reside typically in a similarly rich environment as quiescent galaxies on a physical scale of ~2-8Mpc, and in groups they show a morphological early-to-late type ratio similar to the quiescent galaxy class. With the current data set, we do not find evidence of statistical significant evolution in either the number/mass density of k+a galaxies at intermediate redshift with respect to the local values, or the spectral properties. Those galaxies, which are affected by a sudden quenching of their star-formation activity, may increase the stellar mass of the red-sequence by up to a non-negligible level of ~10%.Comment: 17 pages, 9 figures. Accepted for publication in Astronomy and Astrophysics on 09/09/2009 (no changes wrt v1

The zCOSMOS survey: the role of the environment in the evolution of the luminosity function of different galaxy types

Aims. An unbiased and detailed characterization of the galaxy luminosity function (LF) is a basic requirement in many astrophysical issues: it is of particular interest in assessing the role of the environment in the evolution of the LF of different galaxy types. Methods. We studied the evolution in the B band LF to redshift z ~ 1 in the zCOSMOS 10k sample, for which both accurate galaxy classifications (spectrophotometric and morphological) and a detailed description of the local density field are available. Results. The global B band LF exhibits a brightening of ~0.7 mag in M^* from z ~ 0.2 to z ~ 0.9. At low redshifts (z -20), while the bright end is populated mainly by spectrophotometric early types. At higher redshift, spectrophotometric late-type galaxies evolve significantly and, at redshift z ~ 1, the contribution from the various types to the bright end of the LF is comparable. The evolution for spectrophotometric early-type galaxies is in both luminosity and normalization: M* brightens by ~0.6 mag but φ^∗ decreases by a factor ~1.7 between the first and the last redshift bin. A similar behaviour is exhibited by spectrophotometric late-type galaxies, but with an opposite trend for the normalization: a brightening of ~0.5 mag is present in M^*, while φ^∗ increases by a factor ~1.8.
Studying the role of the environment, we find that the global LF of galaxies in overdense regions has always a brighter M^* and a flatter slope. In low density environments, the main contribution to the LF is from blue galaxies, while for high density environments there is an important contribution from red galaxies to the bright end.
The differences between the global LF in the two environments are not due to only a difference in the relative numbers of red and blue galaxies, but also to their relative luminosity distributions: the value of M^* for both types in underdense regions is always fainter than in overdense environments. These results indicate that galaxies of the same type in different environments have different properties.
We also detect a differential evolution in blue galaxies in different environments: the evolution in their LF is similar in underdense and overdense regions between z ~ 0.25 and z ~ 0.55, and is mainly in luminosity. In contrast, between z ~ 0.55 and z ~ 0.85 there is little luminosity evolution but there is significant evolution in φ^∗, that is, however, different between the two environments: in overdense regions φ^∗ increases by a factor ~1.6, while in underdense regions this increase reaches a factor ~2.8. Analyzing the blue galaxy population in more detail, we find that this evolution is driven mainly by the bluest types. Conclusions. The “specular” evolution of late- and early-type galaxies is consistent with a scenario where a part of blue galaxies is transformed in red galaxies with increasing cosmic time, without significant changes in the fraction of intermediate-type galaxies. The bulk of this tranformation in overdense regions probably happened before z ~ 1, while it is still ongoing at lower redshifts in underdense environments