3,110 research outputs found
Draft toxicological profile for JP-5, JP-8, and jet A fuels
No full textA Toxicological Profile for JP-5 and JP-8 was released in 1998. This present edition supersedes any previously released draft or final profile.Chemical manager(s)/author(s): John Risher, Obaid Faroon, ATSDR, Division of Toxicology and Human Health Sciences, Atlanta, GA; Fernando Llados, Lisa Ingerman, Mario Citra, SRC, Inc., North Syracuse, NY
The relationship between serotonin, decision-making and mood
No full textThe serotonin (5-HT) system has been implicated in both depression and reward and punishment processing. This thesis presents data from four studies designed to better understand the role of serotonin in decision-making and mood. Following the general introduction and description of the main experimental methods, the first experimental chapter presents a study that examined the relationship between naturally-varying 5-HT1A receptor availability, measured using positron emission tomography, and decision-making in healthy volunteers. This study identified correlations between 5-HT1A receptor availability in the hippocampal complex and both impulsivity and sensitivity to the probability of an outcome during decision-making. The second experimental chapter examined decision-making in healthy volunteers 3 days following MDMA (3,4-methylenedioxymethamphetamine) administration, when serotonin transmission is thought to be reduced. A specific type of decision-making process, “pruning” (the reflexive avoidance of aversive outcomes when searching through a tree of potential decisions), was significantly attenuated 3 days following MDMA administration. However, the expected positive relationship between the attenuation in this decision-making process and low mood was not observed. The third experimental chapter attempted to extend this finding using the acute tryptophan depletion method, which removes tryptophan (the precursor to serotonin) from the diet and is thought to reduce serotonin synthesis. Performance on three decision making tasks (pruning, gambling and impulsivity) was examined in healthy volunteers following tryptophan depletion. Results revealed that treatment decreased participants’ choosing of high probability gambles. The final chapter examined pruning in unmedicated depressed patients, and found that they behaved very similarly to healthy volunteers when evaluating aversive outcomes in the context of a tree of potential decisions, despite the hypothesised disruption to the serotonin system in this disorder. These experiments provide a more complete understanding of the relationship between serotonin, decision-making and mood, and are discussed in relation to theories of depression that pose a central role for disrupted decision-making
Shock tube study of JP-10 ignition delay time
No full textJP-10 (exo-tetrahydrodicyclopentadiene, C10H16) ignition delay times were measured in a preheated shock tube. The vapor pressures of the JP-10 were measured directly by using a high-precision vacuum gauge, to remedy the difficulty in determining the gaseous concentrations of heavy hydrocarbon fuel arising from the adsorption on the wall in shock tube experiments. The whole variation of pressure and emission of the OH or CH radicals were observed in the ignition process by a pressure transducer and a photomultiplier with a monochromator. The emission of the OH or CH radicals was used to identify the time to ignition. Experiments were performed over the pressure range of 151-556 kPa, temperature range of 1000-2100 K, fuel concentrations of 0.1%-0.55% mole fraction, and stoichiometric ratios of 0.25, 0.5, 1.0 and 2.0. The experimental results show that for the lower and higher temperature ranges, there are different dependency relationships of the ignition time on the temperature and the concentrations of JP-10 and oxygen
Neural and Behavioural Correlates of Empathy and Morality and their Associations with Psychopathic Traits
No full textPsychopathy is a personality disorder that can be defined by profound disturbances in empathic response to others and repeated engagement in immoral behaviour. This thesis set out to investigate how individual differences in psychopathic traits in the general population are associated with variability in distinct components of empathy and morality. This thesis endeavoured to answer five outstanding research questions: 1) Given the complexity and multidimensionality of empathy and morality constructs, which components of these constructs are associated with psychopathic traits at the behavioural level? [Chapters 2-3] 2) Are behavioural correlates of empathy and morality in psychopathic traits specific to affective-interpersonal traits/lifestyle-antisocial traits, or common to both? [Cs. 2-3] 3) Are these correlates consistent across genders? [Cs. 2-3] 4) Are associations between psychopathic traits and empathic [C. 4] and 5) moral processing reflected at the neural level [C. 5]? This thesis’ findings suggest that: 1) individual differences in psychopathic traits are associated with lesser empathic response to emotional stimuli, lesser propensity to feel moral emotions and atypical moral decision-making; 2) empathic atypicalities are driven by the joint variance between affective-interpersonal and lifestyle-antisocial facets, but those related to affective aspects of moral cognition seem to be driven by variance in affective-interpersonal traits; 3) empathic and moral atypicalities seem to be similar in men and women; 4) atypical amygdala and anterior insula function may represent neural markers of disrupted empathic processing for individuals with high levels of psychopathic traits; and 5) atypical functioning of the vmPFC/mOFC during moral processing may contribute to the disordered lifestyle and antisocial behaviour exhibited by individuals with high levels of psychopathic traits. These findings contribute to a more comprehensive understanding of the empathic and moral processing impairments that underlie psychopathic traits
The interaction between emotion and economic decision-making
No full textEmotions play an important role in daily life decisions. For example, we are likely to choose, judge, or evaluate things around us in different ways depending on whether we are feeling sad, anxious, or happy. Emotional reactions to life events and outcomes, such as winning an award, or getting a divorce, should also predict individuals’ subsequent decisions. However, the mechanisms by which such interactions between emotions and decisions unfold are still poorly understood. The aim of this thesis was two-fold: first, to characterize a computational model of how emotions are integrated into decisions; second, to provide a better understanding of the cognitive and neural mechanisms by which manipulating emotions can alter decisions. Following the general introduction and methods description, the first experimental chapter shows that integrating emotions (self-report feelings) in a computational model of decision-making could reliably predict people’s gambling choices, indicating a unique contribution of feelings to decisions. The second experimental chapter explores the influence of incidental emotional priming on gambling choice and the underlying neural mechanisms, using functional magnetic resonance imaging (fMRI). The findings suggest that how external emotions impact decisions, at both behavioural and neural levels, varied with individual differences in levels of trait anxiety. The third experimental chapter attempts to extend this finding by testing how risky decisions are altered in patients with clinical anxiety, relative to healthy controls; demonstrating a dissociation between sensitivity to risk, which was enhanced in anxiety, and sensitivity to monetary losses, which was not associated with anxiety. This thesis provides a more complete understanding of the complex interactions between emotions, mood and decision-making. In the final chapter the findings are discussed in light of influential theories in cognitive neuroscience and behavioural economics that posit a central role for emotions in determining the choices we make
Dynamics of Network Formation Processes in the Co-Author Model
No full textThis article studies the dynamics in the formation processes of a mutual consent network in game theory setting: the Co-Author Model. In this article, a limited observation is applied and analytical results are derived. Then, 2 parameters are varied: the number of individuals in the network and the initial probability of the links in the network in its initial state. A simulation result shows a finding that is consistent with an analytical result for a state of equilibrium while it also shows different possible equilibria.Dynamics, Network, Game Theory, Model,Simulation, Equilibrium, Complexity
An equivalent formulation of the Fan-Raspaud Conjecture and related problems
No full textIn 1994, it was conjectured by Fan and Raspaud that every simple bridgeless cubic graph has three perfect matchings whose intersection is empty. In this paper we answer a question recently proposed by Mkrtchyan and Vardanyan, by giving an equivalent formulation of the Fan-Raspaud Conjecture. We also study a possibly weaker conjecture originally proposed by the first author, which states that in every simple bridgeless cubic graph there exist two perfect matchings such that the complement of their union is a bipartite graph. Here, we show that this conjecture can be equivalently stated using a variant of Petersen-colourings, we prove it for graphs having oddness at most four and we give a natural extension to bridgeless cubic multigraphs and to certain cubic graphs having bridges
Habenula responses during appetitive and aversive conditioning in major depressive disorder
No full textThe lateral habenula (LHb) has been shown to respond to cues that predict aversive stimuli in non-human primates (Matsumoto & Hikosaka, 2009, Nat Neurosci, 12 (1), 77-84) and has been implicated in reinforcement processing and the pathophysiology of major depression (MDD) (Roiser et al, Biol Psychiatry, 66 (5), 441-450), possibly via reciprocal connections with monoaminergic nuclei. We report the first high-resolution fMRI investigation of haemodynamic responses during appetitive and aversive conditioning in the LHb in unipolar MDD. Additionally, we report the first assessment of tonic habenula function using quantitative Arterial Spin Labelling (ASL) in MDD
Ephemisms as communication vehicle in the Tiv language and literature
No full textThe beauty of Tiv language and literature is achieved when communication or discourse is laced with euphemistic expressions. Euphemisms aid in turning impolite utterances into polite ones. This study, therefore, investigates the communicative potentials of euphemisms in the Tiv language and literature. The study discusses formations of euphemisms, classifies euphemisms and explores the effects of euphemisms. Connotative theory of meaning has been deployed in this study because the interpretation of euphemisms is contextually and connotatively loaded. Methodologically, the author used primary and secondary materials. The author used a participant-observation tool for data collection. Being a native speaker of the Tiv language, the author collected, translated and classified euphemisms. Secondary materials were sourced from textbooks, journal articles, online sources and dictionaries. The following findings were made: euphemisms constitute phrasal or idiomatic synonyms; they beautify or spice our daily communication; they can becloud meanings. This study will benefit preachers, writers, lecturers/teachers, researchers, semanticists, public speakers, politicians and students
Open Access to Peer-Reviewed Research through Author/Institution Self-Archiving: Maximizing Research Impact by Maximizing Online Access
No full textAll refereed journals will soon be available online; most of them already are. This means that anyone will be able to access them from any networked desk-top. The literature will all be interconnected by citation, author, and keyword/subject links, allowing for unheard-of power and ease of access and navigability. Successive drafts of pre-refereeing preprints will be linked to the official refereed draft, as well as to any subsequent corrections, revisions, updates, comments, responses, and underlying empirical databases, all enhancing the self-correctiveness, interactivity and productivity of scholarly and scientific research and communication in remarkable new ways. New scientometric indicators of digital impact are also emerging <http://opcit.eprints.org> to chart the online course of knowledge. But there is still one last frontier to cross before science reaches the optimal and the inevitable: Just as there is no longer any need for research or researchers to be constrained by the access-blocking restrictions of paper distribution, there is no longer any need to be constrained by the impact-blocking financial fire-walls of Subscription/Site-License/Pay-Per-View (S/L/P) tolls for this give-away literature. Its author/researchers have always donated their research reports for free (and its referee/researchers have refereed for free), with the sole goal of maximizing their impact on subsequent research (by accessing the eyes and minds of fellow-researchers, present and future) and hence on society. Generic (OAi-compliant) software is now available free so that institutions can immediately create Eprint Archives in which their authors can self-archive all their refereed papers for free for all forever <http://www.eprints.org/>. These interoperable Open Archives <http://www.openarchives.org> will then be harvested into global, jointly searchable "virtual archives" (e.g., <http://arc.cs.odu.edu/>). "Scholarly Skywriting" in this PostGutenberg Galaxy will be dramatically (and measurably) more interactive and productive, spawning its own new digital metrics of productivity and impact, allowing for an online "embryology of knowledge.
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