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Suggestibility in functional neurological disorder: A meta-analysis
No full textObjective Responsiveness to direct verbal suggestions (suggestibility) has long been hypothesized to represent a predisposing factor for functional neurological disorder (FND) but previous research has yielded conflicting results. The aim of this study was to quantitatively evaluate whether FND patients display elevated suggestibility relative to controls via meta-analysis.Methods Four electronic databases were searched in November 2019, with the search updated in April 2020, for original studies assessing suggestibility using standardized behavioural scales or suggestive symptom induction protocols in FND (including somatization disorder) patients and controls. The metaanalysis followed Cochrane, PRISMA, and MOOSE guidelines. Data extraction and study quality coding were performed by two independent reviewers. Standardized suggestibility scores and responsiveness to symptom induction protocols were used to calculate standardized mean differences (SMDs) between groups.Results Of 26,643 search results, 19 articles presenting 11 standardized suggestibility datasets (FND: n=316; control: n=360) and 11 symptom suggestibility datasets (FND: n=1285; control: n=1409) were included in random-effects meta-analyses. Meta-analyses revealed that FND patients displayed greater suggestibility than controls on standardized behavioural scales (SMD, 0.48 [95% CI, 0.15, 0.81]) and greater responsiveness to suggestive symptom induction (SMD, 1.39 [95% CI, 0.92, 1.86]). Moderation analyses presented mixed evidence regarding the extent to which effect sizes covaried with methodological differences across studies. No evidence of publication bias was found.Conclusions These results corroborate the hypothesis that FND is characterized by heightened responsiveness to verbal suggestion. Atypical suggestibility may confer risk for FND and be a cognitive marker that can inform diagnosis and treatment of this condition
Performance Deterioration of Rotorcraft Engines fitted with Particle Separators
No full textMilitary rotorcraft engines operating in harsh environments routinely ingest large quantities of mineral dust, which can degrade components and ultimately reduce operability. Time off-wing for unscheduled maintenance is a costly burden, both financially and operationally. Rapidly predicting engine deterioration rates as a function of the mission presents an opportunity to optimise flow of supplies, better manage fleets, and perform safety risk assessments when dust loading is expected to be particularly high. In the current contribution, we present our ongoing efforts in this field with a new methodology for assessing the effectiveness of inertial particle separators and quantifying the changes they impart to the inbound dust. We demonstrate that both the concentration reduction and the modification to the particle size distribution can be made on the basis of a single independent variable - a generalised Stokes number for inertial particle separators - and a single performance parameter - the corrected separation efficiency. To develop these parameters we conduct numerical simulations of the flow through a generic axi-symmetric inertial particle separator, over a range of five mass flow rates, three scavenge mass flow rates, and 16 particle diameters. In addition to this, a framework is presented to enable an estimation of the dust concentration at the engine intake. This is achieved by correlating the total wake strength to an existing dust landing trial dataset. A coupled rotorcraft-engine model is then used to combined the two methodologies to investigate the influence of engine mass flow rate on dust ingestion rate. A weak non-linear relationship is observed, which arises due to the simultaneous increase in wake strength with engine mass flow rate as rotor power requirements increase. The additional dust stirred up by the stronger wake leads causes this non-linearity. Finally, we show that an improvement in separation efficiency caused by higher engine mass flow rate is far outweighed by the associated increase in dust loading in this condition
Guest-controlled incommensurate modulation in a meta-rigid metal-organic framework material
No full textStructural transitions of host systems in response to guest binding dominate many chemical processes. We re-port an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible “peri-odic-to-aperiodic” structural transition, resulting from a drastic distortion of a [ZnO4N] node controlled by the specific host-guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher dimensional (3+2)D space. We have visualised directly the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H2O upon dehydration to give MFM-520. Filling of MFM-520 with CO2 and SO2 reveals that while CO2 has a minimal structural influence, SO2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO2 under flue-gas-desulfurisation conditions, and the facile release of captured SO2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO2
How external perturbations affect the chemoselectivity of substrate activation by cytochrome P450 OleT
No full textCytochrome P450 enzymes are versatile biocatalysts found in most forms of life. Generally, the cytochrome P450s react with dioxygen and hence are haem-based mono-oxygenases; however, in specific isozymes, H2O2 rather than O2 is used and these P450s act as peroxygenases. The P450 OleTJE is a peroxygenase that binds long to medium chain fatty acids and converts them to a range of products originating from C-hydroxylation, C-hydroxylation, C‒C desaturation and decarboxylation. There is still controversy regarding the details of the reaction mechanism of P450 OleTJE; how the products are formed and whether the product distributions can be influenced by external perturbations. To gain further insights into the structure and reactivity of P450 OleTJE, we set up a range of large active site model complexes as well as full enzymatic structures and did a combination of density functional theory studies and quantum mechanics/molecular mechanics calculations. In particular, the work focused on the mechanisms leading to these products under various reaction conditions. Thus, for a small cluster model, we find a highly selective C-hydroxylation pathway that is preferred over C‒H hydrogen atom abstraction by at least 10 kcal mol‒1. Introduction of polar residues to the model, such as an active site protonated histidine residue or through external electric field effects, lowers the C‒H hydrogen atom abstraction barriers, while a full QM/MM model brings the C‒H and C‒H hydrogen atom abstraction barriers within 1 kcal mol‒1. Our studies; therefore, implicate that environmental effects in the second-coordination sphere can direct and guide selectivities in enzymatic reaction mechanisms
Adaptive landscapes challenge the “lateral-to-sagittal” paradigm for mammalian vertebral evolution
No full textThe evolution of mammals from their extinct forerunners, the non-mammalian synapsids, is one of the most iconic locomotor transitions in the vertebrate fossil record. In the limb skeleton, the synapsid-mammal transition is traditionally characterized by a shift from a sprawling limb posture, resembling that of extant reptiles and amphibians, to more adducted limbs, as seen in modern-day mammals. Based on proposed postural similarities between early synapsids and extant reptiles, this change is thought to be accompanied by a shift from ancestral reptile-like lateral bending to mammal-like sagittal bending of the vertebral column. To test this “lateral-to-sagittal” evolutionary paradigm, we used combinatorial optimization to produce functionally informed adaptive landscapes and determined the functional trade-offs associated with evolutionary changes in vertebral morphology. We show that the synapsid adaptive landscape is different from both extant reptiles and mammals, casting doubt on the reptilian model for early synapsid axial function, or indeed for the ancestral condition of amniotes more broadly. Further, the synapsid-mammal transition is characterized not only by increasing sagittal bending in the posterior column, but also high stiffness, and increasing axial twisting in the anterior column. Therefore, we refute the simplistic lateral-to-sagittal hypothesis, and instead suggest the synapsid-mammal locomotor transition involved a more complex suite of functional changes linked to increasing regionalization of the backbone. These results highlight the importance of fossil taxa for understanding major evolutionary transitions
The compensatory protective effects of social support at work in presenteeism during the Covid pandemic
No full textThe present study investigated the lasting effects of sickness presenteeism on well-being and innovative job performance in the demanding Chinese work context compounded with the precarity of the post pandemic business environment. Adopting the conservation of resources (COR) theory perspective, especially its proposition of compensation of resources, we incorporated social resources at work (supervisory support and collegial support) as joint moderators in the presenteeism-outcomes relationship. We employed a panel design in which all variables were measured twice with six months in between. Data were obtained from 323 Chinese employees working in diverse industries in Taiwan. We found that after controlling for the baseline level of well-being, presenteeism did not have a lasting effect on employees’ exhaustion. However, presenteeism did have a negative lasting effect on employees’ innovative behavior 6 months later. Moreover, we found a significant 3-way interaction of presenteeism, supervisory support and collegial support on employees’ innovative job performance, after controlling for the baseline level of performance. Specifically, when working under illness, employees displayed the best innovative performance with high levels of both supervisory and collegial support, the worst performance with both support being low, and the intermediate when any one of the support being high. This can be taken as the preliminary evidence to support the COR proposition of resource caravans, showing that supervisory support and collegial support compensated for each other as critical resources in alleviating the impact of working under sickness on employees’ innovative performance. Theoretical implications of the findings are discussed, taking into account the macro-cultural context of the East Asian Confucian societies. We also reflected on the managerial implications of the lasting damages of sickness presenteeism and benefits of mobilizing social resources on employees’ well-being and performance
One year on: an updated systematic review of SARS-CoV-2, COVID-19 and audio-vestibular symptoms
No full textOBJECTIVE: The aim was to systematically review the literature to December 2020, in order to provide a timely summary of evidence on COVID-19 and audio-vestibular symptoms. DESIGN: The protocol was registered in the International Prospective Register of Systematic Reviews. The methods were developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Risk of bias was assessed using the National Institute of Heath quality assessment tools.STUDY SAMPLE: After rejecting 850 records, 28 case reports/series and 28 cross-sectional studies met the inclusion criteria.RESULTS: There are multiple reports of hearing loss (e.g., sudden unilateral), tinnitus and rotatory vertigo in adults having a wide range of COVID-19 symptom severity. The pooled estimate of prevalence, based primarily on retrospective recall of symptoms, is 7.6% (CI: 2.5-15.1), 14.8% (CI: 6.3-26.1) and 7.2% (CI: 0.01-26.4), for hearing loss, tinnitus and rotatory vertigo, respectively. However, these could be an over-estimate because it was not always clear that studies were reporting a change in symptom. CONCLUSION: There are multiple reports of audio-vestibular symptoms associated with COVID-19. However, there is a dearth of high-quality studies comparing COVID-19 cases and controls. <br/
A multi-objective Dyna-Q based routing in wireless mesh network
No full textRouting is an essential part for network deployment to maintain and improve the networkperformance. With the rapid demands of various wireless applications, delay and energyefficiency are two fundamentally important aspects in the next-generation communication.A multi-objective Dyna-Q based routing (MODQR) approach to improve both delay andenergy performances is proposed in this paper. For delay, the interference, asymmetricallink condition and probability of transmission failure (PTF) are considered. When derivingthe PTF, the gray physical interference model is used. For energy, the ratio of consumedenergy to energy capacity is used to monitor energy condition. Reinforcement learning is aneffective way to solve the routing problem in a network with uncertain conditions. A pathcan be chosen by iterative exploration and exploitation. Dyna-Q is an effective reinforcementlearning algorithm which can increase the convergence speed. To the best of our knowledge,Dyna-Q is used to solve the multi-objective routing problem for the first time. The path withleast end-to-end delay and largest energy efficiency will be selected. Simulation results showthat MODQR can obtain up to 80.97%, 83.48% and 86.15% better network performancethan three other state-of-the-art routing methods
pH changes induce an axial ligand effect on nonheme iron(IV)-oxo complexes with an appended aminopropyl functionality
No full textNonheme iron enzymes often utilize a high-valent iron(IV)-oxo species for the biosynthesis of natural products, but their high reactivity often precludes structural and functional studies of these complexes. In this work, a combined experimental and computational study is presented on a biomimetic nonheme iron(IV)-oxo complex bearing an aminopyridine macrocyclic ligand and its reactivity towards olefin epoxidation upon changing the identity and coordination ability of the axial ligand. Herein, we show a dramatic effect of the pH on the oxygen atom transfer reaction with substrates. In particular, these changes have occurred due to protonation of the axial-bound pendant amine group, where its coordination to iron is replaced by a solvent molecule or anionic ligand. This axial ligand effect influences the catalysis and we observe enhanced cyclooctene epoxidation yields and turnover numbers in the presence of the unbound protonated pendant amine group. Density functional theory studies were performed to support the experiments and highlight that the replacement of the pendant amine with a neutral or anionic ligand lowers the rate-determining barriers of cyclooctene epoxidation dramatically. The computational work further establishes that the change in oxygen atom transfer is due electrostatic interactions of the pendant amine cation that favorably affects barrier heights