Incidence of Behavior Problems in Toddlers and Preschool Children from Families Living in Poverty

Few studies have examined the incidence of behavior problems in toddlers and preschool children from families living in poverty. The available research suggests behavior problems occur at higher rates in children living in poverty and may have long-term negative outcomes if not identified and properly treated. This study included an ethnically representative sample of 357 children, five years of age and younger, from a diverse, low-income, urban area. All families’ incomes met the federal threshold for living in poverty. Behavior problems were assessed by parent report through a questionnaire specifically designed for low-income families. Boys and younger children were reported as demonstrating a higher rate of externalizing behaviors than girls and older children. The overall rate of children scoring at least one standard deviation above the sample\u27s mean for challenging behaviors was 17.4% and was not related to the child\u27s gender, age or ethnicity. This study also sampled children\u27s positive behaviors, which is unique in studies of behavior problems. Gender and age were not related to the frequency of reported positive behaviors. Ethnicity did influence scores on the positive scale. African American children appeared to present their parents more difficulty on items reflecting cooperative behaviors than Caucasian or Latino children. The implications of the study are discussed based on the recognized need for universal screening of behavior problems in young children and the small number professional training programs targeting the identification and treatment of early childhood behavior problems, despite the availability of evidence-based treatment programs tailored to young children in low-income families

Aligator.jl - A Julia Package for Loop Invariant Generation

We describe the Aligator.jl software package for automatically generating all polynomial invariants of the rich class of extended P-solvable loops with nested conditionals. Aligator.jl is written in the programming language Julia and is open-source. Aligator.jl transforms program loops into a system of algebraic recurrences and implements techniques from symbolic computation to solve recurrences, derive closed form solutions of loop variables and infer the ideal of polynomial invariants by variable elimination based on Gr\"obner basis computation

Hadronic multiparticle production in extensive air showers and accelerator experiments

Using CORSIKA for simulating extensive air showers, we study the relation between the shower characteristics and features of hadronic multiparticle production at low energies. We report about investigations of typical energies and phase space regions of secondary particles which are important for muon production in extensive air showers. Possibilities to measure relevant quantities of hadron production in existing and planned accelerator experiments are discussed.Comment: To be published in Proceedings of ICRC 2005, 29th International Cosmic Ray Conferenc

Seasonal dynamics of benthic communities in a shallow sublitoral site of Laguna estuarine system (South, Brazil)

The seasonal variability of the benthic community in a shallow sublittoral site was analyzed at the Laguna Estuarine System, a chocked lagoon in South Brazil. Seasonal replicate samples for the microphytobenthos, meiofauna and macrofauna were undertaken from October 2003 to October 2004. The analysis of the different component of the benthos permitted to show a clear temporal asynchrony in the microphytobenthos biomass, meiofauna and macrofauna univariate measures increase and decline. Sediment chlorophyll a and phaeopigments followed a similar seasonal trend, with low biomass in the winter, higher in the summer and intermediate values in spring and autumn. The benthic fauna components of the Laguna Estuarine System also showed a clear seasonal oscillation, but with an opposite pattern of variation. Whilst the number of species and abundance of the macrofauna were significantly higher in the spring and summer, for the meiofauna, both the number of taxa and abundances were significantly higher during the winter and autumn. The results of this study suggested that the divergent seasonal variations of the meiofauna and macrofauna may be linked to their different life strategies, and that biological interactions between meiofauna and macrofauna may also play a significant role in structuring these communites.The seasonal variability of the benthic community in a shallow sublittoral site was analyzed at the Laguna Estuarine System, a chocked lagoon in South Brazil. Seasonal replicate samples for the microphytobenthos, meiofauna and macrofauna were undertaken from October 2003 to October 2004. The analysis of the different component of the benthos permitted to show a clear temporal asynchrony in the microphytobenthos biomass, meiofauna and macrofauna univariate measures increase and decline. Sediment chlorophyll a and phaeopigments followed a similar seasonal trend, with low biomass in the winter, higher in the summer and intermediate values in spring and autumn. The benthic fauna components of the Laguna Estuarine System also showed a clear seasonal oscillation, but with an opposite pattern of variation. Whilst the number of species and abundance of the macrofauna were significantly higher in the spring and summer, for the meiofauna, both the number of taxa and abundances were significantly higher during the winter and autumn. The results of this study suggested that the divergent seasonal variations of the meiofauna and macrofauna may be linked to their different life strategies, and that biological interactions between meiofauna and macrofauna may also play a significant role in structuring these communites

The Starburst Nature of Lyman-Break Galaxies: Testing UV Extinction with X-rays

We derive the bolometric to X-ray correlation for a local sample of normal and starburst galaxies and use it, in combination with several UV reddening schemes, to predict the 2--8 keV X-ray luminosity for a sample of 24 Lyman-break galaxies in the HDF/CDF-N. We find that the mean X-ray luminosity, as predicted from the Meurer UV reddening relation for starburst galaxies, agrees extremely well with the Brandt stacking analysis. This provides additional evidence that Lyman-break galaxies can be considered as scaled-up local starbursts and that the locally derived starburst UV reddening relation may be a reasonable tool for estimating the UV extinction at high redshift. Our analysis shows that the Lyman-break sample can not have far-IR to far-UV flux ratios similar to nearby ULIGs, as this would predict a mean X-ray luminosity 100 times larger than observed, as well as far-IR luminosities large enough to be detected in the sub-mm. We calculate the UV reddening expected from the Calzetti effective starburst attenuation curve and the radiative transfer models of Witt & Gordon for low metallicity dust in a shell geometry with homogeneous or clumpy dust distributions and find that all are consistent with the observed X-ray emission. Finally, we show that the mean X-ray luminosity of the sample would be under predicted by a factor of 6 if the the far-UV is unattenuated by dust.Comment: 7 pages, 3 figures. Accepted for publication in A

Starbursts and Star Clusters in the Ultraviolet

Hubble Space Telescope ultraviolet (UV) images of nine starburst galaxies reveal them to be highly irregular, even after excluding compact sources (clusters and resolved stars). Most (7/9) are found to have a similar intrinsic effective surface brightnesses, suggesting that a negative feedback mechanism is setting an upper limit to the star formation rate per unit area. All starbursts in our sample contain UV bright star clusters indicating that cluster formation is an important mode of star formation in starbursts. On average about 20% of the UV luminosity comes from these clusters. The brightest clusters, or super star clusters (SSC), are preferentially found at the very heart of starbursts. The size of the nearest SSCs are consistent with those of Galactic globular clusters. The luminosity function of SSCs is well represented by a power law with a slope alpha ~ -2. There is a strong correlation between the far infrared excess and the UV spectral slope. The correlation is well modeled by a geometry where much of their dust is in a foreground screen near to the starburst, but not by a geometry of well mixed stars and dust.Comment: 47 pages, text only, LaTeX with aaspp.sty (version 3.0), compressed postscript figures available at ftp://eta.pha.jhu.edu/RecentPublications/meurer

Dust emission from the lensed Lyman break galaxy cB58

We detect 1.2mm continuum emission from dust in the gravitationally lensed Lyman break galaxy MS 1512+36-cB58. Our detected flux is surprisingly low: relative to local starburst galaxies, cB58 appears to produce somewhat less far-IR emission than its UV reddening predicts. After comparing several different estimates of the source's dust content, we conclude that the apparent discrepancy is most likely related to uncertainty in its UV spectral slope. Alternate scenarios to account for a far-IR "deficit" which rely on a high dust temperature or differential magnification are less satisfactory. Our result underscores one of the risks inherent in characterizing the cosmic star formation history from rest-UV data alone.Comment: 5 pages, 1 figure, accepted by A&A Letter