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The contexts where drugs are self-administered play an important role in regulating persistent drug taking and in relapse to such taking after periods of abstinence. Here, we review the behavioral and brain mechanisms enabling contexts to promote and prevent relapse to drug seeking. We review the key brain structures, their neuropharmacology and their connectivity. We discuss the similarities and differences between the mechanisms for context-induced reinstatement of drug seeking vs. other forms of relapse to drug seeking in animal models and we highlight the numerous deficits in our understanding. We emphasize that current understanding, although significant, defies explanations in terms of models at the level of brain structures and their connectivity. Rather, we show that there is significant functional compartmentalization and segregation within these structures during reinstatement and extinction of drug seeking that parallels their anatomical segregation into circuits and channels. A key challenge is to recognize this complexity, understand how these circuits and channels are organized, as well as understand how different modes of activity of ensembles of neurons within them promote abstinence or relapse to drug seeking. [ABSTRACT FROM AUTHOR]

Examines polyolefin-organoclay nanocomposites containing a synthetic tetrasilisic fluoromica. Preparation of the nanocomposites from metallocene-catalyzed and conventional Ziegler-Natta-catalyzed linear low-density polyethylenes; Effects of maleic-anhydride grafted compatibilizer; Crystallization; Dynamic mechanical thermal analysis.

A letter to the editor is presented in response to the article on antenatal sonographic findings of congenital anterior urethral diverticulum.

Many clinicians use ultrasound estimates of fetal weight to assess fetal growth. This study assessed the accuracy of the Hadlock IV equation, the equation used at the Royal Hospital for Women, Randwick, NSW, in estimating birth weight. The accuracy of the Hadlock IV equation was assessed based on systematic and random error as well as absolute error. 709 women who underwent ultrasound examination within 8 weeks of delivery between January 2009-May 2011 were included. 305 women underwent ultrasound less than 2 weeks before delivery. The systematic, random and absolute errors of the Hadlock IV equation were -0.47, 27.45 and 8.52%, respectively. This study demonstrates that clinicians may rely on ultrasound estimates of fetal weight performed by well-trained staff in a tertiary institution within 2 weeks of delivery. The accuracy diminishes as the interval between testing and delivery increases. Absolute errors tended to increase with increasing birth weight for all ultrasound-delivery intervals., (© 2013 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.)

Transvaginal ultrasound with an empty bladder is recommended as a standardised ultrasonic technique for the accurate diagnosis of the retroverted uterus. Using this method, the prevalence of the retroverted uterus in 480 general gynaecological patients attending for subspecialist gynaecological ultrasound was 18%. The anteverting effect of the full bladder required for transabdominal ultrasound reduces the prevalence of the retroverted uterus to 13% (P < 0.001).