Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt

The nucleation of a droplet of stable cylinder phase from a metastable lamellar phase is examined within the single-mode approximation to the mean-field Landau–Brazovskii model for diblock copolymer melts. By employing a variational ansatz for the droplet interfacial profile, an analytic expression for the interfacial free energy of an interface of arbitrary orientation between cylinders and lamellae is found. The interfacial free energy is anisotropic and is lower when the cylinder axis is perpendicular to the interface than when the cylinders lie along the interface. Consequently, the droplet shape computed via the Wulff construction is lens like, being flattened along the axis of the cylinders. The size of the critical droplet and the nucleation barrier are determined within classical nucleation theory. Near the lamellar–cylinder phase boundary, where classical nucleation theory is applicable, critical droplets of size 30–400 cylinders across with aspect ratios of 4–10 and nucleation barriers of (30–40)kBT are typically found. The general trend is to larger critical droplets, higher aspect ratios, and smaller nucleation barriers as the mean-field critical point is approached

Online prevention of postpartum depression for Spanish- and English-speaking pregnant women: A pilot randomized controlled trial

AbstractBackgroundPostpartum depression (PPD) is a maternal mental health problem that affects women from all regions of the world. Unfortunately, even in developed countries, half of the cases go undetected and, consequently, untreated. Individuals from low and middle income countries trend toward underutilization of mental health services, partly due to the limited number of available psychological resources. The primary aims of this pilot randomized controlled trial were to adapt to the Internet using the Mothers and Babies Course/Curso Mamás y Bebés, a prevention of PPD intervention, to describe the characteristics of the pregnant women who engaged in the intervention site, and to obtain preliminary data on the efficacy of the Internet intervention to reduce the risk of PPD.MethodsPregnant women, 18years or older who were interested in using the site for themselves were recruited and randomly assigned to a fully-automated self-help Internet intervention or to an information-only control condition. Randomized participants were invited to complete monthly depression assessments up to six months postpartum. To examine the prevention effects of the Internet intervention, pregnant women who did not meet current criteria for a major depressive episode, who engaged with the study website, and who provided depression data during the postpartum follow-up period were included in the study analyses.ResultsParticipants were 111 predominantly Spanish-speaking (82.9%) and Latino/Hispanic (71.3%) pregnant women residing in 23 countries worldwide. The effect of the prevention intervention condition failed to reach significance at the a priori alpha-level. However, the observed coefficient trended in the hypothesized direction (b=−0.514, χ2 (1)=3.43, p=.061; HR=0.598). The benefits of receiving the e-MB Internet intervention were greater for pregnant women reporting high (vs. low) levels of prenatal depression symptoms (b=−0.605, χ2 (1)=5.20, p=.023).ConclusionsThis study provides preliminary evidence that Internet interventions are a promising method toward expanding the reach of psychological resources to perinatal women at-risk for PPD

Outcomes from an Entry-level Occupational Therapy Doctoral Practice-Scholar Apprenticeship Program

The introduction of the occupational therapy doctoral (OTD) program to the field of occupational therapy (OT) education was intended to advance the field by developing future leaders, increasing advanced practice, and promoting scholarship in practice. Limited information to date is available regarding outcomes of the OTD program related to the future research potential of graduates. One such approach to promoting the scholarship of practice among OTD graduates is the use of the practice-scholar model. The practice-scholar model is designed to build research skills among OTD students to encourage their ongoing commitment to evidence-based practice through implementing their own research in practice. Founded in 2014, the Northern Arizona University (NAU) entry-level OTD program has implemented the practice-scholar model through their practice-scholar apprenticeship (PSA) program. The NAU PSA program involves a mentorship experience with OTD students engaging in faculty and/or community clinician led research. The purpose of this paper is to share evaluation results of the NAU PSA program related to the research development among the program’s graduates. NAU OTD students completed pre and post surveys regarding their expectations towards research and a post qualitative feedback session. Students reported statistically significant improvements in their research self-efficacy skills. Qualitatively students identified their developed research skills, the importance of research and their desire to continue implementing research in the future. The field of OT should continue to identify structural ways to support research in practice to realize the potential of future OTD practitioners

Optical Fiber Systems and Methods

One embodiment of the invention includes a method for forming an optical fiber. The method comprises providing a preform having a core material and a glass cladding material surrounding the core material. The method also comprises drawing the preform at a temperature that is greater than a melting temperature of the core material to form a drawn fiber. The method further comprises cooling the drawn fiber to form the optical fiber having a crystalline fiber core and a cladding that surrounds the crystalline fiber core and extends axially along a length of the crystalline fiber core

Advances in studying phasic dopamine signaling in brain reward mechanisms

The last sixty years of research has provided extraordinary advances of our knowledge of the reward system. Since its discovery as a neurotransmitter by Carlsson and colleagues (1), dopamine (DA) has emerged as an important mediator of reward processing. As a result, a number of electrochemical techniques have been developed to measure DA in the brain. Together, these techniques have begun to elucidate the complex roles of tonic and phasic DA signaling in reward processing and addiction. In this review, we will first provide a guide for the most commonly used electrochemical methods for DA detection and describe their utility in furthering our knowledge about DA's role in reward and addiction. Second, we will review the value of common in vitro and in vivo preparations and describe their ability to address different types of questions. Last, we will review recent data that has provided new mechanistic insight of in vivo phasic DA signaling and its role in reward processing and reward-mediated behavior

Studying the Longest ‘Legal’ U.S. Same-Sex Couples: A Case of Lessons Learned

We review methodological opportunities and lessons learned in conducting a longitudinal, prospective study of same-sex couples with civil unions, recruited from a population-based sample, who were compared with same-sex couples in their friendship circle who did not have civil unions, and heterosexual married siblings and their spouse. At Time 1 (2002), Vermont was the only US state to provide legal recognition similar to marriage to same-sex couples; couples came from other US states and other countries to obtain a civil union. At Time 2 (2005), only one US state had legalized same-sex marriage, and at Time 3 (2013) about half of US states had legalized same-sex marriage, some within weeks of the onset of the Time 3 study. Opportunities included sampling legalized same-sex relationships from a population; the use of heterosexual married couples and same-sex couples not in legalized relationships as comparison samples from within the same social network; comparisons between sexual minority and heterosexual women and men with and without children; improvements in statistical methods for non-independence of data and missing data; and the use of mixed methodologies. Lessons learned included obtaining funding, locating participants over time as technologies changed, and on-going shifts in marriage laws during the study

Differential role of ventral tegmental area acetylcholine and N-methyl-D-aspartate receptors in cocaine-seeking

Exposure to drug-associated cues evokes drug-seeking behavior and is regarded as a major cause of relapse. Cues evoke burst firing of ventral tegmental area (VTA) dopamine (DA) neurons and phasic DA release in the nucleus accumbens (NAc). Cholinergic and glutamatergic input to the VTA is suggested to gate phasic DA activity. However, the role of VTA cholinergic and glutamatergic receptors in regulating phasic dopamine release and cue-induced drug-seeking in cocaine experienced subjects is not known. In male Sprague-Dawley rats, we found that VTA inactivation strongly inhibited, while VTA stimulation promoted, cocaine-seeking behavior during early withdrawal. Blockade of phasic activated D1 receptors in the NAc core also strongly inhibited cue-induced cocaine-seeking--suggesting an important role of phasic DA activity in the VTA to NAc core circuit. Next, we examined the role of VTA acetylcholine receptors (AChRs) and N-methyl-D-aspartate receptors (NMDARs) in regulating both NAc core phasic DA release and cue-induced cocaine-seeking. In cocaine naïve subjects, VTA infusion of the nicotinic acetylcholine receptor (AChR) antagonist mecamylamine, the muscarinic AChR antagonist scopolamine, or the NMDAR antagonist AP-5, led to robust attenuation of phasic DA release in the NAc core. During early cocaine withdrawal, VTA infusion of AP-5 had limited effects on NAc phasic DA release and cue-induced cocaine-seeking while VTA infusion of mecamylamine or scopolamine robustly inhibited both phasic DA release and cocaine-seeking. The results demonstrate that VTA AChRs, but not NMDARs, strongly regulate cue-induced cocaine-seeking and phasic DA release during early cocaine withdrawal