579 research outputs found
Climate change memes to prevent anxious dreams : using humor as a coping mechanism for climate change anxiety
Concern about global warming can lead to climate change anxiety, a form of anxiety characterized by excessive worry about the climate crisis and associated consequences on the natural world and human society. It has been suggested by previous research that humor can be used to manage feelings of anxiety. This study seeks to determine if this phenomenon can be applied specifically to climate change anxiety. The research combines a comprehensive literature review with an online survey that leveraged climate change themed internet memes as a proxy for humor to gather opinions about the intersections between these two topics. The survey data supplemented claims made by existing literature, indicating that climate change themed internet memes and humor in general can be useful coping mechanisms to mitigate feelings of climate anxiety. The survey was completed by 93 respondents; most of these participants were women, located in the US, and/or between the ages of 20 and 29. Results from the survey showed that people tend to feel best about their environmental anxiety when they are taking active steps to solve the problem. Conscious decisions such as reducing waste or participating in activist movements are easier to recognize and self-report than more passive coping skills. Reliance on humor was reported as a supplementary coping skill, but many respondents indicated that looking at humorous climate change themed memes did influence their feelings about climate change overall. The scope of this study was relatively small in scale, therefore the results presented in this thesis may not be indicative of broader social trends and likely require further research
Increasing Complexity of a Diterpene Synthase Reaction with a Single Residue Switch
Terpene synthases often catalyze complex reactions involving intricate series of carbocation intermediates. The resulting, generally cyclical, structures provide initial hydrocarbon frameworks that underlie the astonishing structural diversity of the enormous class of terpenoid natural products (\u3e50,000 known), and these enzymes often mediate the committed step in their particular biosynthetic pathway. Accordingly, how terpene synthases specify product outcome has drawn a great deal of attention. In previous work, we have shown that mutational introduction of a hydroxyl group at specific positions within diterpene synthase active sites can short circuit complex cyclization and/or rearrangement reactions, resulting in the production of simpler \u27 diterpenes. Here we demonstrate that the converse change, substitution of an Ile for Thr at the relevant position in a native pimaradiene synthase, leads to a dramatic increase in reaction complexity. Product outcome is shifted from the tricyclic pimaradiene to a rearranged tetracycle, aphidicol-15-ene. Thus, the nature of the residue at this position acts as a true switch for product outcome. In addition, the ability of aliphatic residue substitution to enable a more complex reaction emphasizes the importance of substrate conformation imposed by a largely inert active site. Furthermore, the profound plasticity of diterpene synthases exemplified by this single residue switch for product outcome is consistent with the screening/diversity-oriented hypothesis of natural products metabolism
Evident and latent plasticity across the rice diterpene synthase family with potential implications for the evolution of diterpenoid metabolism in the cereals
The evolution of natural products biosynthetic pathways can be envisioned to occur via a number of mechanisms. Here we provide evidence that latent plasticity plays a role in such metabolic evolution. In particular, rice (Oryza sativa) produces both ent- and syn-copalyl diphosphate (CPP), which are substrates for downstream diterpene synthases. Here we report that several members of this enzymatic family exhibit dual reactivity with some pairing of ent-, syn-, or normal CPP stereochemistry. Evident plasticity was observed, as a previously reported entsandaracopimaradiene synthase also converts syn-CPP to syn-labda-8(17),12E,14-triene, which can be found in planta. Notably, normal CPP is not naturally found in rice. Thus, the presence of diterpene synthases that react with this non-native metabolite reveals latent enzymatic/metabolic plasticity, providing biochemical capacity for utilization of such a novel substrate (i.e., normal CPP) that may arise during evolution, the implications of which are discussed
Probing the promiscuity of ent-kaurene oxidases via combinatorial biosynthesis
The substrate specificity of enzymes from natural products’ metabolism is a topic of considerable interest, with potential biotechnological use implicit in the discovery of promiscuous enzymes. However, such studies are often limited by the availability of substrates and authentic standards for identification of the resulting products. Here, a modular metabolic engineering system is used in a combinatorial biosynthetic approach toward alleviating this restriction. In particular, for studies of the multiply reactive cytochrome P450, ent-kaurene oxidase (KO), which is involved in production of the diterpenoid plant hormone gibberellin. Many, but not all, plants make a variety of related diterpenes, whose structural similarity to ent-kaurene makes them potential substrates for KO. Use of combinatorial biosynthesis enabled analysis of more than 20 such potential substrates, as well as structural characterization of 12 resulting unknown products, providing some insight into the underlying structure–function relationships. These results highlight the utility of this approach for investigating the substrate specificity of enzymes from complex natural products’ biosynthesis
Cardiovascular Magnetic Resonance Imaging of Scar Development Following Pulmonary Vein Isolation: A Prospective Study
Aims Cardiovascular magnetic resonance (MR) provides non-invasive assessment of early (24-hour) edema and injury following pulmonary vein isolation (by ablation) and subsequent scar formation. We hypothesize that 24-hours after ablation, cardiovascular MR would demonstrate a pattern of edema and injury due to ablation and the severity would correlate with subsequent scar. Methods: Fifteen atrial fibrillation patients underwent cardiovascular MR prior to pulmonary vein isolation, 24-hours post (N = 11) and 30-days post (N = 7) ablation, with T2-weighted (T2W) and late gadolinium enhancement (LGE) imaging. Left atrial wall thickness, edema enhancement ratio and LGE enhancement were assessed at each time point. Volumes of LGE and edema enhancement were measured, and the circumferential presence of injury was assessed at 24-hours, including comparison with LGE enhancement at 30 days. Results: Left atrial wall thickness was increased 24-hours post-ablation (10.7±4.1 mm vs. 7.0±1.8 mm pre-PVI, p<0.05). T2W enhancement at 24-hours showed increased edema enhancement ratio (1.5±0.4 for post-ablation, vs. 0.9±0.2 pre-ablation, p<0.001). Edema and LGE volumes at 24-hours were correlated with 30-day LGE volume (R = 0.76, p = 0.04, and R = 0.74, p = 0.09, respectively). Using a 16 segment model for assessment, 24-hour T2W had sensitivity, specificity, and accuracy of 82%, 63%, and 79% respectively, for predicting 30-day LGE. 24-hour LGE had sensitivity, specificity, and accuracy of 91%, 47%, and 84%. Conclusions: Increased left atrial wall thickening and edema were characterized on cardiovascular MR early post-ablation, and found to correlate with 30-day LGE scar
2.5D Flow MRI: 2D phase-contrast of the tricuspid valvular flow with automated valve-tracking
Tricuspid regurgitant velocity is a crucial biomarker in identifying pressure overload in the right heart, associated with diastolic dysfunction and pulmonary hypertension. 2D phase-contrast cannot quantify this flow, and echocardiography is used clinically. We developed a phase-contrast method which utilizes deep-learning algorithms to track the valvular slice in a cardiac phasedependent manner, which we call 2.5D flow. We studied its performance in nine healthy subjects and patients with tricuspid regurgitation. RV stroke volumes correlated better to forward flow volumes by 2.5D flow vs. static 2D phase-contrast (ICC=0.88 vs. 0.62). 2.5D flow characterized regurgitation in a patient
Deuterium imaging of the Warburg effect at sub-millimolar concentrations by joint processing of the kinetic and spectral dimensions
Deuterium metabolic imaging (DMI) is a promising molecular MRI approach, which follows the administration of deuterated substrates and their metabolization. [6,6’-2H2]-glucose for instance is preferentially converted in tumors to [3,3’-2H2]-lactate as a result of the Warburg effect, providing a distinct resonance whose mapping using time-resolved spectroscopic imaging can diagnose cancer. The MR detection of low-concentration metabolites such as lactate, however, is challenging. It has been recently shown that multi-echo balanced steady-state free precession (ME-bSSFP) increases the signal-to-noise ratio (SNR) of these experiments approximately threefold over regular chemical shift imaging; the present study examines how DMI's sensitivity can be increased further by advanced processing methods. Some of these, such as compressed sensing multiplicative denoising and block-matching/3D filtering, can be applied to any spectroscopic/imaging methods. Sensitivity-enhancing approaches were also specifically tailored to ME-bSSFP DMI, by relying on priors related to the resonances' positions and to features of the metabolic kinetics. Two new methods are thus proposed that use these constraints for enhancing the sensitivity of both the spectral images and the metabolic kinetics. The ability of these methods to improve DMI is evidenced in pancreatic cancer studies carried at 15.2 T, where suitable implementations of the proposals imparted eightfold or more SNR improvement over the original ME-bSSFP data, at no informational cost. Comparisons with other propositions in the literature are briefly discussed
Wet Paint: Visual Culture in a Changing Britain – A Round Table Debate
Political decisions and debates regarding the interregional and interna- tional partnerships that constitute Great Britain, including those over Scottish Independence, EVEL (English Votes for English Laws) and proposed legislation on an ‘in/out’ referendum on British membership of the European Union, have contributed to, and intensified, the examination of Britain’s institutions, as well as its national emblems and arche- types. In light of such a dynamic situation, Visual Culture in Britain has asked representatives of British universities, the museum sector and research centres to respond to the idea of a changing Britain through the prism of British art and visual culture, using cogent examples wherever possible, and to outline their observations, understandings and positions within this rapidly developing context
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