Two rival hypotheses have been proposed for the origin of the compact radio flux observed in radio-quiet quasars (RQQs). It has been suggested that the radio emission in these objects, typically some two or three orders of magnitude less powerful than in radio-loud quasars (RLQs), represents either emission from a circumnuclear starburst or is produced by radio jets with bulk kinetic powers ∼ 1...

It is now generally agreed that some process prevents the diffuse gas in galaxy clusters from cooling significantly, although there is less agreement about the nature of this process. I suggest that cluster gas may be heated by a natural extension of the mechanism establishing the MBH − σ and MBH −Mbulge relations in galaxies, namely outflows resulting from super–Eddington accretion on to the g...

OBJECTIVE This study examines the association between having a history of dating violence and the sexual health of adolescent females. METHODS Black adolescent females (n = 522) completed a survey that assessed dating violence, defined as ever having a physically abusive boyfriend, and an interview that assessed sexual behaviors. RESULTS Dating violence was reported by 18.4% of adolescents ...

The oldest rocks which have been found so far (on the Earth) date to about 3.8 to 3.9 billion years ago (by several radiometric dating methods). Some of these rocks are sedimentary, and include minerals which are themselves as old as 4.1 to 4.2 billion years. Rocks of this age are relatively rare, however rocks that are at least 3.5 billion years in age have been found on North America, Greenla...

Human modification of natural landscapes has influenced surface processes in many settings on Earth. Quantitative data comparing the distribution and behavior of geologic phenomena before and after human arrival are sparse but urgently required to evaluate possible anthropogenic influences on geologic hazards. We conduct field and imagery-based mapping, statistical analysis, and numerical model...

OBJECTIVE To estimate the prevalence of cyber dating abuse among youth aged 14 to 19 years seeking care at school-based health centers and associations with other forms of adolescent relationship abuse (ARA), sexual violence, and reproductive and sexual health indicators. METHODS A cross-sectional survey was conducted during the 2012-2013 school year (participant n = 1008). Associations betwe...

BACKGROUND The present investigation expands upon prior studies by examining the relationship between health in late adolescence and the experience of physical/sexual and non-physical dating violence victimization, including dating violence types that are relevant to today's adolescents (e.g., harassment via email and text messaging). We examined the relationship between physical/sexual and non...

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OBJECTIVES To assess the co-occurrence of past-month physical assault of a dating partner and violence against peers and siblings among a locally representative sample of high school students and to explore correlates of dating violence (DV) perpetration. DESIGN Cross-sectional survey design. SETTING Twenty-two public high schools in Boston, Massachusetts. PARTICIPANTS A sample of urban h...