CDM, Feedback and the Hubble Sequence

We have performed TreeSPH simulations of galaxy formation in a standard LCDM cosmology, including effects of star formation, energetic stellar feedback processes and a meta-galactic UV field, and obtain a mix of disk, lenticular and elliptical galaxies. The disk galaxies are deficient in angular momentum by only about a factor of two compared to observed disk galaxies. The stellar disks have approximately exponential surface density profiles, and those of the bulges range from exponential to r^{1/4}, as observed. The bulge-to-disk ratios of the disk galaxies are consistent with observations and likewise are their integrated B-V colours, which have been calculated using stellar population synthesis techniques. Furthermore, we can match the observed I-band Tully-Fisher (TF) relation, provided that the mass-to-light ratio of disk galaxies, (M/L_I), is about 0.8. The ellipticals and lenticulars have approximately r^{1/4} stellar surface density profiles, are dominated by non-disklike kinematics and flattened due to non-isotropic stellar velocity distributions, again consistent with observations.Comment: 6 pages, incl. 4 figs. To appear in the proceedings of the EuroConference "The Evolution of Galaxies: II - Basic Building Blocks", Ile de La Reunion (France), 16-21 October 2001 (Slightly updated version). A much more comprehensive paper about this work with links to pictures of some of the galaxies can be found at http://babbage.sissa.it/abs/astro-ph/020436

Supplementary education at college and its consequences for individuals\u27 labor market outcomes in the United States

The current study seeks to expand our knowledge on extended education and its potential contribution to social inequality by examining socioeconomic disparities in supplementary education (SE) at college and its impact on labor market outcomes. Using data from the United States Education Longitudinal Study, logistic and linear regressions deliver the following main findings: (1) Socioeconomic status (SES) significantly affects SE participation, net of other factors. (2) With higher involvement in SE activities, neither employment nor income prospects significantly increase. (3) Low SES graduates are slightly more likely to benefit from SE than high SES graduates. (4) Among high-impact SE practices, only internships exert a positive effect on labor market outcomes. (DIPF/Orig.

Objectively Measured Sedentary Behavior in Preschool Children: Comparison Between Montessori and Traditional Preschools

Background: This study aimed to compare the levels of objectively-measured sedentary behavior in children attending Montessori preschools with those attending traditional preschools. Methods: The participants in this study were preschool children aged 4 years old who were enrolled in Montessori and traditional preschools. The preschool children wore ActiGraph accelerometers. Accelerometers were initialized using 15-second intervals and sedentary behavior was defined as/15-second. The accelerometry data were summarized into the average minutes per hour spent in sedentary behavior during the in-school, the afterschool, and the total-day period. Mixed linear regression models were used to determine differences in the average time spent in sedentary behavior between children attending traditional and Montessori preschools, after adjusting for selected potential correlates of preschoolers’ sedentary behavior. Results: Children attending Montessori preschools spent less time in sedentary behavior than those attending traditional preschools during the in-school (44.4. min/hr vs. 47.1 min/hr, P=0.03), after-school (42.8. min/hr vs. 44.7 min/hr, P=0.04), and total-day (43.7 min/hr vs. 45.5 min/hr, P = 0. 009) periods. School type (Montessori or traditional), preschool setting (private or public), socio-demographic factors (age, gender, and socioeconomic status) were found to be significant predictors of preschoolers’ sedentary behavior. Conclusions: Levels of objectively-measured sedentary behavior were significantly lower among children attending Montessori preschools compared to children attending traditional preschools. Future research should examine the specific characteristics of Montessori preschools that predict the lower levels of sedentary behavior among children attending these preschools compared to children attending traditional preschools

Diagnosis of flood events in Brisbane (Australia) using a flood index based on daily effective precipitation

Like drought, flood events are extremely detrimental to the community [1, 2]. In the State of Queensland (Australia) the 2010–2011 Summer period saw a very significant flooding that appeared to be exacerbated by La Nina, with damages of magnitudes similar to previous flood in 1974 and mid-1950s [3]. Therefore, a plethora of flood events in this region raises serious questions about how best to address the vulnerability and costs [4]. Several studies documented particularly vulnerable geographic setting of the capital city, Brisbane. To name a few, the worst event was in January 1974 and next in 2010, which flooded most dwellings around Brisbane River catchment, severely in Toowoomba and the Lockyer Creek catchment (where 23 people had drowned). Insurers received some 56,200 claims with payouts totaling $2.55 billion, due to estimated inundations of 18,000 properties. Crucial to any flood mitigation and adaptation is the prediction of events with a good real-time monitoring system. The system should detect precisely the onset dates and corresponding water-intensive properties. A flood event is dependent on how abundant the water resources due to heavy rain are and how the water is dissipated over time. Hence a scientific method for detecting floods should be based on remaining effective precipitation on daily basis, due to heavy rain over a period of time. In this paper we applied an obje400+-ctive flood diagnostic method following an earlier pioneer study [6]. The Flood Index (FI) used in this research was initially developed by [6] based on the concept of daily Effective Precipitation (EP) proposed by [7] using the Available Water Resources Index (AWRI), and later used by [8] for analysis of water abundant seasons. The daily FI was applied to the flood region of Brisbane, the state capital of Queensland, Australia (27°30' S, 153°1' E). In order to compute the FI, the pre-processed daily rainfall data was acquired from Australian Bureau of Meteorology (http://www.bom.gov.au/climate/data-services/). Data for the period 1915–2012 were analysed. Since the FI was a standardized value comparing daily water resources for any Julian date to the yearly maximum values over climatological period, it detected flood starting date (for FI > 0) and represented adequately anomalously high precipitation that potentially triggered flood situation. The severity, intensity and durations were analysed by running sum approach of [9] over identified flood periods between onset and termination dates. Our results demonstrated good skill of the daily Flood Index for objective diagnosis and monitoring of flood events based on water intensive properties. The method allowed for the detection of the event, and quantified its properties for comparison of various events. The method was novel for quantifying floods and appears quite promising for forecasting flood events using time-series approaches

An Atlas of Monte Carlo Models of Dust Extinction in Galaxies for Cosmological Applications

We present an extensive study of the radiative transfer in dusty galaxies based on Monte Carlo simulations. The main output of these simulations are the attenuation curves ${\cal A}_\lambda$ (i.e. the ratio between the observed, dust extinguished, total intensity to the intrinsic unextinguished one of the galaxy as a function of wavelength). We have explored the dependence of ${\cal A}_\lambda$ on a conspicuous set of quantities (Hubble type, inclination, dust optical thickness, dust distribution and extinction properties) for a large wavelength interval, ranging from 1250\AA to the K band, thus finally providing a comprehensive atlas of dust extinction in galaxies, which is electronically available. This study is particularly suitable for inclusion into galaxy formation evolution models and to directly interpret observational data on high redshift galaxies.Comment: 29 pages, aasms4.sty, LaTeX, 5 figures. ApJSS, accepte

Stellar Populations and the Local Group Membership of the Dwarf Galaxy DDO 210

We present deep BVI CCD photometry of the stars in the dwarf galaxy DDO 210. The color-magnitude diagrams of DDO 210 show a well-defined red giant branch (RGB) and a blue plume. The tip of the RGB is found to be at I_TRGB = 20.95 +/- 0.10 mag. From this the distance to DDO 210 is estimated to be d = 950 +/- 50 kpc. The corresponding distance of DDO 210 to the center of the Local Group is 870 kpc, showing that it is a member of the Local Group. The mean metallicity of the red giant branch stars is estimated to be [Fe/H] = -1.9 +/- 0.1 dex. Integrated magnitudes of DDO 210 within the Holmberg radius (r_H=110 arcsec = 505 pc) are derived to be M_B=-10.6 +/- 0.1 mag and M_V=-10.9 +/- 0.1 mag. B and V surface brightness profiles of DDO 210 are approximately consistent with an exponential law with scale lengths r_s(B) = 161 pc and r_s(V) = 175 pc. The brightest blue and red stars in DDO 210 (BSG and RSG) are found to be among the faintest in the nearby galaxies with young stellar populations: _{BSG} = -3.41 +/- 0.11 mag and _{RSG} = -4.69 +/- 0.13 mag. An enhancement of the star formation rate in the recent past (several hundred Myrs) is observed in the central region of DDO 210. The opposite trend is observed in the outer region of the galaxy, suggesting a possible two-component structure of the kind disk/halo found in spiral galaxies. The real nature of this two-component structure must, however, be confirmed with more detailed observations.Comment: Latex file, 17 pages with 9 figures, uses emulateapj.sty To appear in the AJ (in August 1999

A photo-ionized canopy for the shock-excited Criss-Cross Nebula

Aims. We study a new broad well-defined arc of optical nebulosity close to the cloud-shock interacting Criss-Cross Nebula, derive the basic physical properties of the former and revise those of the latter, and compare both objects to simulations of cloud-shock interactions from the literature. Methods. Deep optical, partly wide-field, images were used to reveal the intricate morphology and overall extent of the nebulosities. Optical spectroscopy enabled us to uncover their nature. Results. The two nebulosities obviously are physically linked, but are of different type; the Criss-Cross Nebula is, as was shown also in an earlier paper, excited via a slow shock from the expanding Orion-Eridanus Bubble, but the broad arc is definitely photo-ionized. The source for ionizing photons appears to be hot gas in this bubble. Some results of simulations of interactions of SNRs with interstellar clouds available from the literature bear a striking resemblance to our nebulae, which appear to represent an example - unrivalled in closeness and clarity - for an early to medium stage in the destruction of an isolated cloud over-run by a highly evolved SNR. Thereby the Criss-Cross Nebula is, when seen from the SNR, the rear disrupted part of the original small cloud, whereas the arc probably is its yet rather intact front part.Comment: 6 pages, 3 figures. Figures degraded because of size constraints. Accepted for publication in A&

Soft X-Ray Sources at the Centers of the Elliptical Galaxies NGC 4472 and NGC 4649

Analysis of recent Chandra observations of the elliptical galaxies NGC 4472 and NGC 4649 has revealed faint soft X-ray sources at their centers. The sources are located to within 1'' of the optical centers of the galaxies. They are most likely associated with the central supermassive black holes. Interest in these and several other similar objects stems from the unusually low luminosity of the supermassive black holes embedded in dense interstellar medium. Our Chandra sources have very soft spectra. They are detectable only below ~0.6 keV and have luminosities in the 0.2-2.5 keV energy band of ~ 6 * 10^{37} erg/s and ~1.7 * 10^{38} erg/s in NGC 4649 and NGC 4472, respectively.Comment: Shortened version of the paper published in Astronomy Letter

Psychometric properties of the Caregiver Preparedness Scale in caregivers of stroke survivors

Objective: To evaluate the psychometric characteristics of the Caregiver Preparedness Scale (CPS) in caregivers of stroke survivors. Background: Caregiver preparedness can have an important impact on both the caregiver and the stroke survivor. The validity and reliability of the CPS has not been tested for the stroke-caregiver population. Methods: We used a cross-sectional design to study a sample of 156 caregivers of stroke survivors. Construct validity of the CPS was evaluated by confirmatory factor analysis (CFA). Internal consistency and test-retest reliability were also evaluated. Results: Caregivers were, on average, 54 year old (SD ¼ 13.2) and most were women (64.7%). CFA supported the unidimensionality of the scale (comparative fit index ¼ 0.98). Reliability was also supported: item-reliability index and itemetotal correlations above 0.30; composite reliability index ¼ 0.93; Cronbach’s alpha ¼ 0.94; factor score determinacy ¼ 0.97; and test-retest reliability ¼ 0.92. Conclusion: The CPS is valid and reliable in caregivers of stroke survivors. Scores on this scale may assist health-care providers in identifying caregivers with less preparedness to provide specific interventions

Fracture Density Estimation Using Spectral Analysis of Reservoir Reflections: A Numerical Modeling Approach

We use a 3-D finite difference numerical model to generate synthetic seismograms from a simple fractured reservoir containing evenly spaced, discrete, vertical fractures. The fractures are represented using a single column of anisotropic grid points. Analysis of seismic amplitudes and spectral characteristics were carried out on the top and base reservoir reflections as well as scattered wave coda for models with fracture spacing ranging from 0.01 to 0.1 fractures/m. Results show that the bulk scattered wave energy contained in a common shot gather increases greatly when the fracture spacing is greater than about 1/4 wavelength. Wavenumber spectra for integrated amplitude versus offset from a time window containing the base reservoir reflector show spectral peaks corresponding to the fracture spacing.United States. Dept. of Energy (Grant DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources LaboratoryEni S.p.A. (Firm