University of Maryland, Baltimore County

About: University of Maryland, Baltimore County is a education organization based out in Baltimore, Maryland, United States. It is known for research contribution in the topics: Population & Aerosol. The organization has 8749 authors who have published 20843 publications receiving 795706 citations. The organization is also known as: UMBC.

Application of the Manakov-PMD equation to studies of signal propagation in optical fibers with randomly varying birefringence

Abstract: We report on our investigations of the Manakov-polarization mode dispersion (PMD) equation which can be used to model both nonreturn-to-zero (NRZ) and soliton signal propagation in optical fibers with randomly varying birefringence We review the derivation of the Manakov-PMD equation from the coupled nonlinear Schrodinger equation, and we discuss the physical meaning of its terms We discuss our numerical approach for solving this equation, and we apply this approach to both NRZ and soliton propagation, We show by comparison with the coupled nonlinear Schrodinger equation, integrated with steps that are short enough to follow the detailed polarization evolution, that our approach is orders of magnitude faster with no loss of accuracy Finally, we compare our approach to the widely used coarse-step method and demonstrate that the coarse-step method is both efficient and valid

The Structure and Coherence of Competence from Childhood through Adolescence

Abstract: The structure and coherence of competence from childhood (ages 8-12) to late adolescence (ages 17-23) was examined in a longitudinal study of 191 children. Structural equation modeling was utilized to test a conceptual model and alternative models. Results suggest that competence has at least 3 distinct dimensions in childhood and 5 in adolescence. These dimensions reflect developmental tasks related to academic achievement, social competence, and conduct important at both age levels in U.S. society, and the additional tasks of romantic and job competence in adolescence. As hypothesized, rule-breaking versus rule-abiding conduct showed strong continuity over time, while academic achievement and social competence showed moderate continuity. Results also were consistent with the hypothesis that antisocial behavior undermines academic attainment and job competence.

Multimodel estimates of intercontinental source-receptor relationships for ozone pollution

Abstract: Understanding the surface O-3 response over a "receptor" region to emission changes over a foreign "source" region is key to evaluating the potential gains from an international approach to abate ozone (O-3) pollution. We apply an ensemble of 21 global and hemispheric chemical transport models to estimate the spatial average surface O-3 response over east Asia (EA), Europe (EU), North America (NA), and south Asia (SA) to 20% decreases in anthropogenic emissions of the O-3 precursors, NOx, NMVOC, and CO (individually and combined), from each of these regions. We find that the ensemble mean surface O-3 concentrations in the base case (year 2001) simulation matches available observations throughout the year over EU but overestimates them by > 10 ppb during summer and early fall over the eastern United States and Japan. The sum of the O-3 responses to NOx, CO, and NMVOC decreases separately is approximately equal to that from a simultaneous reduction of all precursors. We define a continental-scale "import sensitivity" as the ratio of the O-3 response to the 20% reductions in foreign versus "domestic" (i.e., over the source region itself) emissions. For example, the combined reduction of emissions from the three foreign regions produces an ensemble spatial mean decrease of 0.6 ppb over EU (0.4 ppb from NA), less than the 0.8 ppb from the reduction of EU emissions, leading to an import sensitivity ratio of 0.7. The ensemble mean surface O-3 response to foreign emissions is largest in spring and late fall (0.7-0.9 ppb decrease in all regions from the combined precursor reductions in the three foreign regions), with import sensitivities ranging from 0.5 to 1.1 (responses to domestic emission reductions are 0.8-1.6 ppb). High O-3 values are much more sensitive to domestic emissions than to foreign emissions, as indicated by lower import sensitivities of 0.2 to 0.3 during July in EA, EU, and NA when O-3 levels are typically highest and by the weaker relative response of annual incidences of daily maximum 8-h average O-3 above 60 ppb to emission reductions in a foreign region(< 10-20% of that to domestic) as compared to the annual mean response (up to 50% of that to domestic). Applying the ensemble annual mean results to changes in anthropogenic emissions from 1996 to 2002, we estimate a Northern Hemispheric increase in background surface O-3 of about 0.1 ppb a(-1), at the low end of the 0.1-0.5 ppb a(-1) derived from observations. From an additional simulation in which global atmospheric methane was reduced, we infer that 20% reductions in anthropogenic methane emissions from a foreign source region would yield an O-3 response in a receptor region that roughly equals that produced by combined 20% reductions of anthropogenic NOx, NMVOC, and CO emissions from the foreign source

Effects of domestic violence on children's behavior problems and depression.

Abstract: The Children's Depression Inventory, Child Behavior Checklist, and Youth Self-Report were completed by mothers, fathers, and their 8- to 12-year-old children to assess the effects of various types of domestic violence on children's behavior problems and depression. One hundred and ten Israeli children from lower-class families were identified through social service records. Thirty-three of the children had been physically abused by their parents within the last 6 months, 16 had witnessed spouse abuse, 30 had been both victims and witnesses of domestic violence, and 31 had experienced no known domestic violence. Overall, domestic violence had effects on child development that varied in magnitude and nature depending on the type of domestic violence and who reported the information about the child's adjustment. During the past 30 years, domestic violence and its effects on children's development have received considerable attention in the scientific and popular media (Cicchetti & Carlson, 1989). Although there is some evidence that children who are victims and/or witnesses of domestic violence have more social and emotional problems than their nonabused counterparts, findings have varied across studies. Because of the difficulties in recruiting samples, investigators have usually studied children from violent families that are characterized by multiple stressors (e.g., histories of drug and alcohol abuse, single parenting, shelter residence, and poverty) and multiple forms of maltreatment (i.e., neglect, sexual abuse, spouse abuse, and child abuse; Aber & Cicchetti, 1984). Unfortunately, it has been difficult to systematically measure these stresses and to evaluate how they exacerbate, moderate, or mask the effects of maltreatment on