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Early life stress (ELS) is a risk factor for the development of depression in adolescence; the mediating neurobiological mechanisms, however, are unknown. In this study, we examined in early pubertal youth the associations among ELS, cortisol stress responsivity, and white matter microstructure of the uncinate fasciculus and the fornix, two key frontolimbic tracts; we also tested whether and how these variables predicted depressive symptoms in later puberty. A total of 208 participants (117 females; M age = 11.37 years; M Tanner stage = 2.03) provided data across two or more assessment modalities: ELS; salivary cortisol levels during a psychosocial stress task; diffusion magnetic resonance imaging; and depressive symptoms. In early puberty there were significant associations between higher ELS and decreased cortisol production, and between decreased cortisol production and increased fractional anisotropy in the uncinate fasciculus. Further, increased fractional anisotropy in the uncinate fasciculus predicted higher depressive symptoms in later puberty, above and beyond earlier symptoms. In post hoc analyses, we found that sex moderated several additional associations. We discuss these findings within a broader conceptual model linking ELS, emotion dysregulation, and depression across the transition through puberty, and contend that brain circuits implicated in the control of hypothalamic–pituitary–adrenal axis function should be a focus of continued research.
Filamentary structures can form within the beam of protons accelerated during the interaction of an intense laser pulse with an ultrathin foil target. Such behaviour is shown to be dependent upon the formation time of quasi-static magnetic field structures throughout the target volume and the extent of the rear surface proton expansion over the same period. This is observed via both numerical and experimental investigations. By controlling the intensity profile of the laser drive, via the use of two temporally separated pulses, both the initial rear surface proton expansion and magnetic field formation time can be varied, resulting in modification to the degree of filamentary structure present within the laser-driven proton beam.
The counter tube diffractometer method for determining d spacings is often rejected for precision work because of lack of information concerning the nature and significance of the inherent errors. Errors concerned with the geometry of the method, the nature of the X-ray source, and the technique of collecting data have all been analyzed previously in some detail. The findings of these analyses, which are scattered throughout the literature, are reviewed briefly. Errors arising from imperfections in the instrument and misalignment of the X-ray source with respect to the diffractometev have been studied experimentally. The results are presented and discussed in terms of the resultant error in the determination of the lattice parameter of a cubic crystal. Errors determined both analytically and empirically are discussed in relation to the extrapolation procedures commonly used for diffractometers. It is shown that, depending on the construction of the instrument, the effect of imperfections in the gears may almost double the error in the final extrapolated value of a lattice parameter.
The availability of counter-tube diffractometers which can scan both sides of the direct beam makes it possible to locate the zero-angle position by comparing peak positions measured on either side of the beam. These diffractometers may thus be used to determine accurate lattice parameters without the need of a calibrating substance. The feasibility of this method is explored by determining the lattice parameters of pure silver, and the limits of accuracy are discussed.
Synchrotron X-radiation provides unique opportunities for diffraction experiments and, therefore, for extending our understanding of the structure - property interplay in catalyst systems. The present status of opportunities and applications of synchrotron X-ray diffraction techniques in the structural chemistry and catalysis science areas is overviewed, and illustrated by selected recent results.
Neuropsychological dysfunction is a well-established finding in individuals with bipolar disorder type I (BP-I), even during euthymic periods; however, it is less clear whether this also pertains to bipolar disorder type II (BP-II) or those with subthreshold states (SBP; subthreshold bipolar disorder), such as bipolar not otherwise specified (BP-NOS). Herein, we compare the literature regarding neuropsychological performance in BP-II vs BP-I to determine the extent of relative impairment, and we present and review all related studies on cognition in SBP. After systematically searching PubMed, Medline, PsycINFO, and The Cochrane Library, we found 17 papers that comprise all the published studies relevant for this review. The areas that are consistently found to be impaired in BP are executive function, verbal memory, visual spatial working memory, and attention. More studies than not show no significant difference between BP-I and BP-II, particularly in euthymic samples. Preliminary evidence suggests that patients experiencing major depressive episodes who also meet criteria for SBP show similar profiles to BP-II; however, these results pertain only to a depressed sample. SBP were found to perform significantly better than both MDD and healthy controls in a euthymic sample. A consensus on mood state, patient selection, and neuropsychological testing needs to be agreed on for future research. Furthermore, no studies have used the most recent DSM-5 criteria for SBP; future studies should address this. Finally, the underlying bases of cognitive dysfunction in these diagnostic groups need to be further investigated. We suggest recommendations on all of the above current research challenges.
Researchers are becoming increasingly interested in linking specific forms of early life stress (ELS) to specific neurobiological markers, including alterations in the morphology of stress-sensitive brain regions. We used a person-centered, multi-informant approach to investigate the associations of specific constellations of ELS with hippocampal and amygdala volume in a community sample of 211 9- to 13-year-old early adolescents. Further, we compared this approach to a cumulative risk model of ELS, in which ELS was quantified by the total number of stressors reported. Using latent class analysis, we identified three classes of ELS (labeled typical/low, family instability, and direct victimization) that were distinguished by experiences of family instability and victimization. Adolescents in the direct victimization class had significantly smaller hippocampal volume than did adolescents in the typical/low class; ELS classes were not significantly associated with amygdala volume. The cumulative risk model of ELS had a poorer fit than did the person-centered model; moreover, cumulative ELS was not significantly associated with hippocampal or amygdala volume. Our results underscore the utility of taking a person-centered approach to identify alterations in stress-sensitive brain regions based on constellations of ELS, and suggest victimization is specifically associated with hippocampal hypotrophy observed in early adolescence.
Philip Rieff's (1922– 2006) intellectual and cultural inheritance derives from a variety of sources. For example, he was not a religious Jew and mentions of the Holocaust hardly make an appearance in his early work. Yet increasingly “Auschwitz” takes on great moral and cultural significance in his late writings. Rieff made his intellectual name with an intellectual biography of Sigmund Freud, co- written with his first wife Susan Sontag. It still stands as a major achievement, even if his own attitude toward Freud moved from admiration to disapproval over the years. As a sociologist, Rieff was influenced by Emile Durkheim's emphasis on the relationship between a society's cohesion and its religious ethos, not to mention Max Weber's writings on authority and his idea of modernity as intertwined with secularization, a special preoccupation of modern German thought. The philosophy of culture hammered out by Friedrich Nietzsche was also of fundamental importance for Rieff's later work, particularly, of course, for his “death of God” anti- theology. Besides that Rieff was steeped in the advanced art and culture of the twentieth century. In this he was a product of an eclectic and pluralist modernist culture.
But as a theorist of culture, Rieff was indifferent to the philosophical tradition of Greece as it has shaped modern thought, particularly German thought. There's no evidence that Rieff accepted Martin Heidegger's version of Western thought as Seinsvergessenheit (the forgetting of Being). Though he admired Hannah Arendt as “one of the most trustworthy guides to our time and its past,” he never really responded to her claim that the history of Western political ideas was the story of the loss of authentic political thinking. And unlike another (adopted) American conservative, Leo Strauss, with whom he is sometimes compared, Rieff did not choose Athens over Jerusalem, rationality over revelation, natural law over God's commandments. Unlike both Strauss and Arendt, he was largely dismissive of politics, which he considered to be the pursuit of crass material interests and power grabbing. Still, in his late writings, he identified the Hellenic origins of the West with what he called the “first world,” one founded on “taboo” and guided by “fate.” The third world, which we the living allegedly now inhabit, sees the world in terms of the “primacy of possibility” (aka POP), and it is guided by “rules” that regulate the roles the self continually tries on and sheds.