Semi-empirical molecular orbital calculations of the ground and excited state potential surfaces for photodissociation of Pararosaniline leucocyanide incorporating solvent stabilization

The excited state and ground state potential surfaces are calculated for the photoionization of Pararosaniline leucocyanide using MNDO-SCF and INDO-SCF-CI molecular orbital methods. These potential surfaces are corrected for influence of polar media using Onsager reaction field theory and incorporating dipole-dipole interaction. These calculations support a mechanism of photochromism in which photodissociation occurs from the first singlet excited state

Learning to Eat French

Ferguson’s Accounting for Taste reveals a gap in our understanding: How did French culinary discourse move beyond the bourgeois sphere in which it emerged in the nineteenth century? Picking up on her comparison of the Proustian synthesis of regional and national culinary culture in the Recherche to the project of national identity creation in the Third Republic’s best-selling textbook, Le Tour de la France par deux enfants, this essay argues that the culinary model Ferguson describes was in fact widely disseminated through mass primary education under the Third Republic. Examining an overlooked corpus of primary school readers and textbooks, I show that food and cooking provided object lessons imparting practical and scientific knowledge to enlighten the masses, and textbooks canonized regional specialties as part of a new national geographic consciousness. At the same time, I underscore the limits of this consensual image of a national culinary culture, which collided with the class habits and horizons of the urban and rural masses attending l’école républicaine

Strategic insight and age-related goal-neglect influence risky decision-making

Maximizing long-run gains often requires taking on some degree of risk, yet decision-makers often exhibit risk aversion: RA), rejecting risky prospects even when these may have higher expected value than safer alternatives. We investigated whether explicit strategy instruction and practice can decrease prepotent RA, and whether aging impacts the efficacy of such an intervention. Participants performed a paired lottery task with options varying in risk and magnitude, both before and after practice with a similar task that encouraged maximization of expected value and instruction to use this strategy in risky decisions. In both younger and older adults, strategy training reduced RA. Although RA was age-equivalent at baseline, larger training effects were observed in younger adults. These effects were not explained by risk-related: i.e., affective) interference effects or computation ability, but were consistent with a progressive, age-related neglect of the strategy across trials. Our findings suggest that strategy training can diminish RA, but that training efficacy is reduced among older adults, in part, due to goal neglect. We discuss implications for neural mechanisms that may distinguish older and younger adults’ risky decision-making

Emotional awareness moderates the relationship between childhood abuse and borderline personality disorder symptom dimensions

Objective: To examine pathways to borderline personality disorder (BPD), focusing on childhood abuse and emotional attention and clarity. Method: Among 293 community residents (mean age = 43.1; 53.9% female), measured associations between the BPD symptom dimensions of disturbed relatedness, affective dysregulation, and behavioral dysregulation and (a) childhood abuse (emotional, physical, and sexual); (b) emotional attention and clarity; and (c) negative affect, using structured interviews, the Schedule for Non-Adaptive and Adaptive Personality-2, the Trait Meta Mood Scale, and the Positive and Negative Affect Scale, respectively. Results: All forms of childhood abuse were associated with BPD symptom dimensions. Emotional attention and clarity moderated the effects of childhood physical and emotional abuse on behavioral dysregulation and disturbed relatedness. All results held when controlling for negative affect. Conclusion: The relations between childhood abuse and BPD are robust. Emotional attention and clarity may help elucidate the links between childhood abuse and BPD

Neural Dynamics Tracking Subjective Cognitive Effort

What patterns of brain activity reflect engagement with highly demanding cognitive tasks? How do these patterns relate to subjective, phenomenal effort? Answering these questions is critical to understanding what causes some people to experience cognitive tasks as more effortful than others. Subjective experience, in turn, is vital, with trait tendencies to exert effort having been linked to career and academic success. High subjective effort, as in schizophrenia and depression, can thus be extremely problematic. And yet, poor operational definitions have constrained research into basic questions about what neural dynamics track subjective effort. Here, a powerful, new behavioral economic operationalization is employed, in combination with fMRI, to investigate brain dynamics corresponding to subjectively costly cognitive effort. Brain regions varying in activity by working memory load and cognitive control demands are strong candidates for tracking subjective effort (Westbrook & Braver, 2015). To identify such regions, I examined BOLD data, collected while participants performed a well established working memory task (the N-back; Kirchner, 1958) that is both subjectively effortful, and for which subjective effort varies as a monotonic function of load (Westbrook et al., 2013). I focused my search within independently-defined networks of nodes that co-vary (within-network) across a wide range of brain states. Specifically, I examined a subset of a priori task-positive networks, as identified by Power et al. (2011), which typically show increasing, and a task-negative network which typically shows decreasing activity with greater load. Importantly, variation was examined over N-back loads for which data has never been published, thus the present study reveals novel insights about activity-load functions in independently-defined functional networks from very low (N = 1) to very high loads (N = 6). As expected, all task-positive networks showed robustly greater activity during the N-back. However, patterns of variation by load differed by network. While the task positive fronto-parietal (FP), dorsal attention (DorAtt), and salience (Sal) networks showed inverted-U functions, peaking mid-range (at the 2- or 3-back) and decreasing after, the cingulo-opercular network (CO) showed robust activity that did not further vary by load. Rather than encoding load per se, the CO simply encoded that a participant was performing the N-back. The task-negative default mode network (DMN) was robustly and increasingly de activated across all load levels examined. Given that both subjective effort (Westbrook et al., 2013) and DMN deactivation are approximately monotonic functions of load, the DMN is a strong candidate for tracking variation in subjective effort with load. By contrast, inverted-U functions in the FP, Sal, and DorAtt networks do not straightforwardly map to monotonically increasing effort. Performance measures instead suggest that inverted-U functions tracked individual differences in adaptive strategy shifting. Namely, when participants were divided by 3-back performance, better performers showed a pronounced inverted-U (over N = 1—3) while worse performers did not. Interestingly, a similar pattern was found when dividing participants according subjective effort, providing tentative support to a hypothesis that subjective effort acts as a cue to shift strategies adaptively under excessive demands. In any case, surprisingly, in none of the networks did load-specific changes in brain activity predict load-specific changes in subjective effort. Critically, although load-specific patterns of brain activity did not predict subjective effort, load-independent brain activity predicted individual differences in subjective effort. Namely, higher average brain activity in any of the task-positive networks predicted greater subjective effort. At the sub-network level, this was notably true for two key regions that have been implicated as core components of a cognitive control system, and also hypothesized to track effort costs: the dorsal anterior cingulate cortex (dACC) and the dorsolateral prefrontal cortex (dlPFC) (McGuire et al., 2010). Importantly, after controlling for performance, the dACC remained a reliable predictor of subjective effort, while the dlPFC did not, supporting that the dACC tracks cognitive effort apart from task difficulty (while the dlPFC may not). This is consistent with strong prior theory implicating the dACC in regulating the intensity of cognitive control in response to flagging performance and in proportion to the expected value of doing so (Shenhav et al., 2013). The present results begin to answer basic questions about how the brain tracks subjective effort. They also lay the foundation for future work addressing why subjective effort can be so much greater for some individuals, like those with schizophrenia or depression, and also future work developing interventions for promoting desirable effort expenditure

Examining ego fidelity

Deficits in individuals’ self-views have been linked to multiple negative psychological outcomes. Although self-views are important for understanding psychopathology, they are not sufficient. Specifically, they fail to capture how individuals’ actions are influenced by their values. We propose a new construct, ego fidelity, to refer to a disposition toward oneself, others, and situations that draws on internal values as a source of motivation. The purpose of the present research is to distinguish ego fidelity from self-esteem and self-efficacy. This research also aims to examine the incremental predictive utility of ego fidelity for understanding why individuals act the way they do in uncertain situations, and to identify features of psychopathology that ego fidelity may help to explain above and beyond related constructs. These goals were achieved across five studies intended to: (1) distinguish ego fidelity from self-esteem and self-efficacy, as well as identify personality factors related to ego fidelity; (2) examine connections between ego fidelity and why individuals act the way they do in uncertain situations; and (3) identify features of psychopathology that ego fidelity may help to explain above and beyond self-esteem or self-efficacy. Finally, the present research aims to validate two measures of the ego fidelity, the Ego Fidelity Scale and the Ego Fidelity Interview. Ego fidelity was found to have some predictive utility above and beyond self-esteem and self-efficacy for certain personality features and traits related to psychopathology (e.g., social anxiety), though further refinement of the measures developed and presented as a result of this research will be necessary to improve of understanding of the relations between these constructs

The pyrolysis of menthol

Research on the pyrolysis or organic compounds has received an increasing amount of attention in recent years. The pyrolysis of terpene hydrocarbons has been of interest primarily because of their wide-spread and abundant natural occurrence. In addition terpenes have been investigated because of their interesting stereochemistry. Menthol is a C10 monocyolic terpene alcohol. Its thermal decomposition at temperatures greater than 500°C has not been investigated previously because of inadequate methods of analysis. The pyrolysis of other terpene hydrocarbons has revealed new routes to useful intermediates from relatively cheap source materials. Menthol, however, has never been considered as a possibility in these studies. The stereochemistry of menthol has led to its extensive use in studying the mechanism of thermal elimination reactions. The mechanism of thermal decomposition in pyrolysis reaction has been reported for several terpene hydrocarbons. Such investigations prior to this study, however, did not include menthol. The objects or this investigation were; a) to study the pyrolysis of menthol from 450° to 750° C and determine the major products of the reaction both qualitatively and quantitatively, and b) to postulate and discuss mechanisms of the pyrolysis based on these results

What do MRI radiographers really know?

Magnetic Resonance Imaging (MRI) is an important diagnostic imaging tool that has seen rapid expansion in recent years with a commensurate increase in the number of radiographers undertaking MRI scans. This imaging modality is a complex one and the strong magnetic fields associated with MRI scanners pose a very serious risk to patients and staff. Therefore it is essential that MR radiographers receive appropriate training in the correct operation and safe use of MRI. The education of radiographers undertaking MRI examinations is largely provided “in-house” by radiographers or applications specialists. This training is usually informal and focuses on essential safety training and the use of scanner software. This learning is not usually formally assessed and therefore its value is not properly evaluated. In 2007 the authors, acting as independent consultants, developed a number of assessment tools to enable quick and effective evaluation of theoretical knowledge and skills related to the clinical use of MRI in a group of individuals with a range of MRI experience. A total of 47 individuals with a range of MRI experience were tested using an Objective Structured Clinical Examination (OSCE). Some were also given a viva voce. Our results show that the majority of radiographers in our sample could not answer more than half the OSCE questions correctly and a significant and unacceptable number did not convince us they could practice MRI safely. Very few of the examinees had adequate knowledge of image quality issues and parameter manipulation. A few also raised concerns over their radiographic credentials

Functional Characterisation of Perovskite Films for Solar Cell Applications

The world is currently faced with an energy dilemma; as global demand for power continues to soar, pressure is mounting to move away from fossil fuels towards low-carbon alternatives. In this setting, highly efficient, low-cost photovoltaics, which turn solar photons into electricity offer an attractive solution. The efficiency of such photovoltaics is essentially underpinned by the competition between extraction and recombination of photogenerated charges. In this thesis, we use a combination of transient optical, structural and device characterisation techniques to elucidate the key factors governing these two processes in perovskite solar cells. In Chapter 3, we address the issue of charge extraction at perovskite|hole transport layer interfaces. We find that a remarkably small driving energy (∆E ∼ 0.1 eV) between the perovskite valence band and the highest occupied molecular orbital (HOMO) of the hole transport layer is required to induce efficient hole injection (> 75%). We also find that the rate of recombination of injected holes in Cs0.05(MA0.17FA0.83)0.95PbI3 systems is slower compared to MAPbI3. In Chapter 4, we show that passivation of perovskite with phenethylammonium iodide results in an enhancement of the efficiency from 12.95% to 16.73% and an improvement in stability – taken as the time for efficiency to drop to 80% of its initial value – from a few hours to over 21 days. Optical characterisation reveals that a bilateral passivation mechanism is behind these improvements, where iodide anions fill iodide vacancies and the phenethylammonium cation induces a 2D heterostructure. Finally, we bring these two strands of research together in Chapter 5 by correlating the extent of passivation from transport layers with an enhancement in the interfacial charge injection yield. Throughout, we make constant reference to the impact of our findings on perovskite solar cell device parameters and set out design rules for their optimum efficiency and stability

Archiving and disseminating integrative structure models.

Limitations in the applicability, accuracy, and precision of individual structure characterization methods can sometimes be overcome via an integrative modeling approach that relies on information from all available sources, including all available experimental data and prior models. The open-source Integrative Modeling Platform (IMP) is one piece of software that implements all computational aspects of integrative modeling. To maximize the impact of integrative structures, the coordinates should be made publicly available, as is already the case for structures based on X-ray crystallography, NMR spectroscopy, and electron microscopy. Moreover, the associated experimental data and modeling protocols should also be archived, such that the original results can easily be reproduced. Finally, it is essential that the integrative structures are validated as part of their publication and deposition. A number of research groups have already developed software to implement integrative modeling and have generated a number of structures, prompting the formation of an Integrative/Hybrid Methods Task Force. Following the recommendations of this task force, the existing PDBx/mmCIF data representation used for atomic PDB structures has been extended to address the requirements for archiving integrative structural models. This IHM-dictionary adds a flexible model representation, including coarse graining, models in multiple states and/or related by time or other order, and multiple input experimental information sources. A prototype archiving system called PDB-Dev ( https://pdb-dev.wwpdb.org ) has also been created to archive integrative structural models, together with a Python library to facilitate handling of integrative models in PDBx/mmCIF format