Amazonian Ayahuasca and Mental Health Outcomes

Ayahuasca is a psychedelic plant brew originating from the Amazon Rainforest. It is formed from two basic components, the Banisteriopsis caapi vine, and a plant containing the potent psychedelic dimethyltryptamine (DMT), usually Psychotria viridis. There has been a dramatic increase in interest surrounding ayahuasca since the turn of the millennium. Increasing numbers of tourists are travelling to the Amazon rainforest to drink the brew, with various media outlets, celebrities, and researchers describing benefit from its consumption. Ayahuasca is now present in every continent and retreat centres offering plant medicine experiences in the Amazon rainforest has become a thriving business. Anecdotal evidence varies significantly, ranging from evangelical accounts to horror stories involving physical and psychological harm. This thesis comprises five studies investigating Amazonian ayahuasca use. Initially, the pharmacology of the brew is explored in the form of a systematic review, concluding complex synergistic mechanisms may be present, although further research is needed. The remaining studies utilise observational methodology, investigating the impact of ayahuasca retreats following a traditional Shipibo lineage adapted for ayahuasca tourists in the Peruvian Amazon. The effects of the brew on personality, mental health outcomes, epigenetics, and nature relatedness are documented. Further, a phenomenological analysis of the ayahuasca experience is included. The research in this thesis is amongst the first to investigate Shipibo-style ayahuasca retreats in the Peruvian Amazon. Various ethical issues surrounding the increasing popularity of the brew and potential medicalisation are also discussed. It is hoped that this research will add to the growing body of knowledge surrounding the potential therapeutic effects of ayahuasca, whilst considering risks, ethics, and wider applications

Annealing kinetics of nanoindentation-induced polycrystalline high pressure phases in crystalline silicon

Transformation kinetics of nanoindented zones in silicon containing high pressure crystalline phases (Si III and Si XII) during annealing (100 °C<T<450 °C) have been studied using Raman microspectroscopy and cross-sectional transmission electron microscopy. Signature peaks associated with Si III/XII in the Raman spectra were monitored to track the annealing of these phases to polycrystalline Si I as a function of annealing time and temperature. An overall activation energy for this transformation was found to be 0.67 eV. During annealing, Si XII disappeared faster than Si III, suggesting either that Si XII first converts to Si III or that Si XII transforms to polycrystalline Si I faster than Si III

Rapid, substrate-independent thickness determination of large area graphene layers

Phase-shifting interferometric imaging is shown to be a powerful analytical tool for studying graphene films, providing quantitative analysis of large area samples with an optical thickness resolution of ≤0.05 nm. The technique is readily able to identify single sheets of graphene and to quantitatively distinguish between layers composed of multiple graphene sheets. The thickness resolution of the technique is shown to result from the phase shift produced by a graphene film as incident and reflected light pass through it, rather than from path-length differences produced by surface height variations. This is enhanced by the high refractive index of graphene, estimated in this work to be nG = 2.99 ± 0.18.The authors wish to acknowledge the Australian Research Council for financial support

Annealing of nanoindentation-induced high pressure crystalline phases created in crystalline and amorphous silicon

Thermally induced phase transformation of Si-III/Si-XII zones formed by nanoindentation has been studied during low temperature (200<T<300 °C) thermal annealing by Raman microspectroscopy and transmission electron microscopy. Two sizes of spherical indenter tips have been used to create substantially different volumes of phase transformed zones in both crystalline (c-Si) and amorphous silicon (a-Si) to study the zone size and starting matrix effects. The overall transformation is from Si-III/XII to poly- or nanocrystalline Si-I through intermediate phases of Si-XIII and Si-IV. Attempts have been made to determine the exact transformation pathways. Two scenarios are possible: either Si-XII first transforms to Si-III before transforming to Si-I through the intermediate phases or that Si-XII goes through the intermediate phases while Si-III transforms directly to Si-I. Finally, the phase transformations are slower in the larger indents and the starting matrix (crystalline or amorphous) has a substantial effect on the transformation kinetics of the small indents compared to the larger ones. We attribute this increased stability to both matrix effects (nucleation) and a difference in overall residual stress in indents made in a-Si compared to c-Si

Phase transformation pathways in amorphous germanium under indentation pressure

Nanoindentation-induced phase transformations have been studied in amorphous Ge thin films. These films initially tend to deform via plastic flow of the amorphous phase under load but at a critical pressure a sudden phase transformation occurs. This transformation, to a soft metallic (β-Sn-like)-Ge phase confined under the indenter, is signified by a "pop-in" event on loading. Following "pop-in," the indentation tests fall into two distinct types of behavior. In one case, the rate of deformation with increasing load after "pop-in" increases, and the observed end-phase following complete unloading is observed to be predominately diamond-cubic Ge. In the other case, the deformation rate (slope of the loading curve) remains the same as that before "pop-in," and the end phases following unloading are found to contain predominantly unstable r8 and more stable hexagonal Ge phases. The different transformation pathways for these two cases are shown to be related to the probability that the soft (β-Sn-like)-Ge phase volume, which suddenly forms at the transformation pressure, is either unconstrained by the indenter tip (the first case) or totally constrained under the indenter tip (in the latter case)

Ceremonial Ayahuasca in Amazonian Retreats—Mental Health and Epigenetic Outcomes From a Six-Month Naturalistic Study

Ayahuasca is a natural psychoactive brew, used in traditional ceremonies in the Amazon basin. Recent research has indicated that ayahuasca is pharmacologically safe and its use may be positively associated with improvements in psychiatric symptoms. The mechanistic effects of ayahuasca are yet to be fully established. In this prospective naturalistic study, 63 self-selected participants took part in ayahuasca ceremonies at a retreat centre in the Peruvian Amazon. Participants undertook the Beck Depression Inventory (BDI-II), State-Trait Anxiety Inventory (STAI), Self-compassion Scale (SCS), Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM), as well as secondary measures, pre- and post-retreat and at 6-months. Participants also provided saliva samples for pre/post epigenetic analysis. Overall, a statistically significant decrease in BDI-II (13.9 vs. 6.1, p &lt; 0.001), STAI (44.4 vs. 34.3 p &lt; 0.001) scores, and CORE-OM scores were observed (37.3 vs. 22.3 p &lt; 0.001) at post-retreat, as well as a concurrent increase in SCS (3.1 vs. 3.6, p &lt; 0.001). Psychometric improvements were sustained, and on some measures values further decreased at 6-month follow-up, suggesting a potential for lasting therapeutic effects. Changes in memory valence were linked to the observed psychometric improvements. Epigenetic findings were equivocal, but indicated that further research in candidate genes, such as sigma non-opioid intracellular receptor 1 (SIGMAR1), is warranted. This data adds to the literature supporting ayahuasca's possible positive impact on mental health when conducted in a ceremonial context. Further investigation into clinical samples, as well as greater analyses into the mechanistic action of ayahuasca is advised

Default mode network modulation by psychedelics : a systematic review

Psychedelics are a unique class of drug that commonly produce vivid hallucinations as well as profound psychological and mystical experiences. A grouping of interconnected brain regions characterized by increased temporal coherence at rest have been termed the Default Mode Network (DMN). The DMN has been the focus of numerous studies assessing its role in self-referencing, mind wandering, and autobiographical memories. Altered connectivity in the DMN has been associated with a range of neuropsychiatric conditions such as depression, anxiety, post-traumatic stress disorder, attention deficit hyperactive disorder, schizophrenia, and obsessive-compulsive disorder. To date, several studies have investigated how psychedelics modulate this network, but no comprehensive review, to our knowledge, has critically evaluated how major classical psychedelic agents-lysergic acid diethylamide, psilocybin, and ayahuasca-modulate the DMN. Here we present a systematic review of the knowledge base. Across psychedelics there is consistent acute disruption in resting state connectivity within the DMN and increased functional connectivity between canonical resting-state networks. Various models have been proposed to explain the cognitive mechanisms of psychedelics, and in one model DMN modulation is a central axiom. Although the DMN is consistently implicated in psychedelic studies, it is unclear how central the DMN is to the therapeutic potential of classical psychedelic agents. This article aims to provide the field with a comprehensive overview that can propel future research in such a way as to elucidate the neurocognitive mechanisms of psychedelics

Social Class

Discussion of class structure in fifth-century Athens, historical constitution of theater audiences, and the changes in the comic representation of class antagonism from Aristophanes to Menander