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Pre-sleep screen time and screen time addiction as shared determinants of poor sleep and obesity in adolescents aged 11-14 years in Scotland
Get PDFFunding: This research was supported by the University of St Andrews as part of a doctoral research programme.Background The overall quantity of screen time has been associated with short sleep duration and increasingly sedentary lifestyles, leading to adiposity. The aim of this research was to explore which components of screen time usage are shared determinants of poor sleep and higher adiposity in adolescents, using data from the Teen Sleep Well Study. Methods A cross-sectional study of adolescents aged 11–14 years in Fife, Scotland was conducted. Sleep was measured objectively using the Actigraph GT3X-BT and subjectively using validated questionnaires. Adiposity was assessed using body fat percentage (BF%) and obesity was measured using body mass index percentile (BMIp). Four components of screen time were addressed using questionnaires: the timing of screen time, quantity of screen time, location of screen time, and screen time addiction. Descriptive statistics and statistical tests such as Pearson correlation tables, and adjusted regression analyses were used. Mediation analyses explored wellbeing as a factor in the association between screen time and sleep and obesity. Results Sixty-two participants (33 female/29 male, mean age 12.2 ± 1.1 years, mean BMIp 60.3 ± 32.1) completed the study. Excessive screen time pre-sleep (30 min before sleep) and post-sleep (first 30 min after waking), excessive screen time on a weekend, and screen time addiction were shared determinants of higher adiposity, a later chronotype (evening-preference) and poor sleep outcomes: poor sleep habits, increased insomnia symptoms (IS) and increased sleep onset variability. Mediation analyses confirmed that adolescent wellbeing mediated the association between pre-sleep screen time and IS (36.3%) and BF% (21.9%), post-sleep screen time and IS (37.7%) and BF% (30.4%), videogaming addiction and IS (31.9%) and BF% (34.6%), social media addiction and IS (35.0%) and BF% (17.4%), mobile phone addiction and IS (34.0%) and BF% (10.6%), weekday screen time and IS (58.1%) and BF% (39.8%), and weekend screen time and IS (51.4%) and BF% (38.0%). Conclusions These screen time behaviours, alongside wellbeing should be considered in multi-component health-promoting interventions aimed at improving adolescent sleep and reducing obesity risk. Future research should employ longitudinal designs to clarify the directionality of these associations and determine the effectiveness of interventions that target both screen time behaviours and wellbeing.Peer reviewe
Distribution and habitat use of deep-diving cetaceans in the central and north-eastern North Atlantic
Get PDFFunding: We acknowledge Colciencias (Departamento Administrativo de Ciencia, Tecnología e Innovación, Colombia), University of St Andrews, and NAMMCO for funding NCRM.Major changes in the distribution of some cetaceans have been observed coincident with changing oceanography of the North Atlantic in the last 30 years. This study aimed to improve understanding of the underlying ecological drivers of any changes in deep-diving cetacean distribution. We used data from two series of summer surveys (in Iceland-Faroes and Norway) to model density of sperm (Physeter macrocephalus), long-finned pilot (Globicephala melas) and northern bottlenose (Hyperoodon ampullatus) whales as a function of static (relief), physical, and biological oceanographic covariates using GAMs. The best models, based on a robust model selection framework, were used to predict distribution. The study period was divided into two periods, 1987-1989 and 1998-2015, based on environmental changes in the area and data availability. The common covariates that best explained these three species’ distributions (in both periods) were bathymetric variables and SST. The selected dynamic temperature-related covariates for sperm and pilot whales were for spring, but for bottlenose whales were for summer. Summer relationships were also found for the three species for the other dynamic variables, except spring chlorophyll-a for bottlenose whales. The difference in seasonal relationships for bottlenose whales may be related to a previously suggested north-south summer migration. As expected, the predicted high-use areas for all three species were deep waters, with some overlap among them in the central Norwegian Sea, and the Central North Atlantic, including the Irminger Sea. Differences in distribution likely reflect differences in prey. Changes in distribution between the two periods appear more as a range expansion than a shift, which could result from an increase in suitable habitat due to warming waters. This new knowledge will help improve understanding of how these species may respond over this wide area to a changing environment and inform their conservation.Peer reviewe
Widespread reforestation before European influence on Amazonia
Get PDFFunding: Ecuadorian work was conducted under Ecuadorian Collection Permit 08-2017-IC. M.B.B. acknowledges funding from the National Science Foundation (grants EAR1338694 and BCS0926973) and the National Aeronautics and Space Administration (grant NNX14AD31G). C.N.H.M. and M.N.N. acknowledge funding from the European Research Council (ERC 2019 StG 853394). M.N.N. also acknowledges a Florida Institute of Technology postdoctoral award. T.K. acknowledges a NERC-funded PhD studentship.An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts.Peer reviewe
The mechanism of ruthenium-catalyzed directed C─H arylation of arenes : the key role of bis-cyclometalated intermediates
Get PDFFunding: The authors thank Engineering and Physical Sciences Research Council (EPSRC) for support via awards EP/L014017/2 (SAM, CLM) and GR/K44619 (NMR at University of Manchester), the European Research Council for an Advanced Grant (RuCat, 833337, IL), Heriot-Watt University for James-Watt Scholarships to SEN and AC, and the University of St. Andrews for financial support (SAM).The mechanism of Ru-catalyzed N-directed C-H ortho-arylation with haloarenes has been under intense scrutiny over the last decade, with conflicting proposals concerning the relevance of various catalytic intermediates and the nature of the key steps. This work presents experimental and computational studies that address these long-standing questions. Stoichiometric, catalytic, and mechanistic kinetic studies, supported by DFT calculations, reveal that bis-cyclometallated ruthenium species are key intermediates in these reactions. These studies also show that oxidative addition with bromoarenes proceeds via a concerted oxidative addition pathway, as demonstrated by DFT and experimental kinetic orders. Bromoarene activation does not proceed at mono-cyclometalated species. In the catalytic process, zero order kinetics are observed on both reaction substrates, an observation that is rationalized by DFT calculations which predict a rate-limiting step within the product-release stage. These results showcase how detailed experimental and DFT studies can combine to probe mechanistic questions, as well as resolving opposing views around the mechanism of these Ru-catalyzed arylations that form the basis of promising mild C─H functionalizations.Peer reviewe
John Witherspoon’s ethics and ‘Sir Isaac Newton’s bulldog’
Get PDFThis article explores the consistency of John Witherspoon’s ethics between Scotland and America by comparing Witherspoon’s (in)famous satire of moderatism, Ecclesiastical Characteristics: Or, the Arcana of Church Policy (Glasgow, 1753), with Witherspoon’s ‘Lectures on Moral Philosophy’, delivered at Princeton from 1769. In doing so, it is the first article to draw attention to, and to assess, the fundamental role that ‘Sir Isaac Newton’s bulldog’, Samuel Clarke, plays in both the Scottish Arcana and American ‘Lectures’. Although scholars frequently debate whether there are ‘two Witherspoons’ – not least because Witherspoon’s American ‘Lectures’ seem to borrow so heavily from his nemesis in Scotland, Francis Hutcheson – it is argued here that Witherspoon’s ethics are consistently Clarkean as opposed to Hutchesonian, in Scotland and America. By investigating the constancy of Witherspoon’s ethics, as underpinned by his consistent use of Clarke, in both the Arcana and ‘Lectures on Moral Philosophy’, this article claims that Clarke’s ethical rationalism and Newtonianism are the key to interpreting Witherspoon’s position on ‘Ethics’ in the ‘Lectures’, as well as appreciating the moral philosophical subtlety of his satirical language in the Arcana.Peer reviewe
How do EU banks’ funding costs respond to the CRD IV? : An assessment based on the banking union directives database
Get PDFFunding: Lena Tonzer and Eleonora Sfrappini have benefited from funding from the European Social Fund ( ESF: ZS/2017/03/84462 ).The establishment of the European Banking Union constitutes a major change in the regulatory framework of the banking system. Main parts are implemented via directives that show staggered transposition timing across EU member states. Based on the newly compiled Banking Union Directives Database, we assess how banks’ funding costs responded to the Capital Requirements Directive IV (CRD IV). We find evidence of a weak increase in funding costs that results from an increase in cost of equity which is mostly offset by a decline in cost of debt. The diverging trends stem from countries with an ex-ante lower regulatory capital stringency and an ex-post quicker activation of capital buffers, which is in line with banks’ short-run adjustment needs but longer-run benefits from increased financial stability.Peer reviewe
Remaking Charles Dickens for 21st-century Russia
No full textCharles Dickens’s writing entered the Russian cultural sphere only a year after he published The Pickwick Papers in England. In 1838, extracts from The Pickwick Papers appeared concurrently in different translations in several Russian journals. Canonical 19th-century writers and thinkers (including Nikolai Gogol, Vissarion Belinsky, Fyodor Dostoevsky, and Lev Tolstoy) read the novels in Russian, French, German, or English, either serialized in journals or as books. The popularity of Dickens in Russian translation was such that by the centenary of his birth in 1912 the third complete works—with new translations of all the novels—had been published. His stories of childhood were by then commonly excerpted and rewritten in magazines for Russian children. During Soviet times, Dickens increased in importance and was embedded in both official and private cultural spheres. His realism, his interest in poverty, and his own childhood experience of deprivation in London all rendered him suitable for retranslation for the new mass reader and for Soviet children, all of whom were to be furnished with negative portrayals of life under capitalism. Despite these propagandistic intentions, children and adults often identified with the suffering of Dickens’s child characters and found comfort in his reliable happy endings. In the Soviet Union, novels by Dickens typically held positive associations of warmth, safety, and moral consistency. They also offered inspiration for imaginative travel to a foreign country they could not dream of visiting in person. This convergence of official and personal appreciations of Dickens resulted in the publication of the most complete of complete works: thirty volumes of completely new translations supported by detailed scholarly apparatus. This so-called dark green edition was published in time for the 150th anniversary of Dickens’s birth in 1962, and a five-kopek postage stamp with a portrait of Dickens was issued in the same year. By the 2000s, a reading public who read Dickens as children in the Soviet Union could now read Dickens in English, on and offline, and even visit London for themselves. Two hundred years after Dickens’s birth, in 2012, the glossy Russian magazine Snob dedicated a special issue to Dickens with new commissions from notable writers including Eduard Limonov, Evgenii Popov, and Marina Stepnova. For the special issue’s editors, Dickens was less a representative of English culture than a conduit of nostalgia for their childhoods in the Soviet Union. At the same time, they noted that Dickens’s reception in Russia had come full circle: from the hypercapitalist publishing environment of Victorian London to the wild capitalism of Putin’s Russia.Peer reviewe
Investigations into perovskite oxides as potential positive electrode materials for potassium-ion batteries
No full textToday, nations worldwide are transitioning from fossil fuels to renewable energy sources to achieve net-zero carbon emissions. Grid-scale energy storage technologies, such as potassium-ion batteries, have gained attention as cost-effective and sustainable alternatives to lithium-ion batteries. However, their commercial adoption remains limited due to the lack of suitable positive electrode materials.
This thesis explores the synthesis, crystal structure, morphology and structural stability of four double perovskite materials, KLaMnWO₆, KLaFeNbO₆ (Ar), KLaFeNbO₆ (reduced), and KLaFeMoO₆-K₂MoO₄, as positive electrode materials for KIB. Their electrochemical performance, including redox reaction, specific capacity, and cycling stability, were also investigated.
KLaMnWO₆ was first investigated due to its previously reported synthesis method by G. King. Structural analysis revealed a potassium deficiency in the as-synthesised KLaMnWO₆, which could not be fully avoided after optimising synthesis conditions. Electrochemical testing demonstrated that KLaMnWO₆ had a low reversible specific capacity of 20 mA h/g after 30 cycles. In-situ/operando X-ray absorption spectroscopy confirmed the Mn²⁺/Mn³⁺ served as the redox couple.
KLaFeNbO₆ was synthesised for the first time in this study under either a pure Ar atmosphere or a reducing atmosphere of 5% H₂ in Ar. The crystal structure of KLaFeNbO₆, with a space group of Pnma, was determined by conducting Rietveld refinements against the neutron powder diffraction data. After particle size reduction and carbon-coating, KLaFeNbO₆ (Ar) presented a reversible specific capacity of 24 mA h/g after 30 cycles, while KLaFeNbO₆ (reduced) showed inferior electrochemical performance.
KLaFeMoO₆-K₂MoO₄ demonstrated the best electrochemical performance among all studied materials. The crystallographic analysis reveals that the double perovskite phase adopts a monoclinic P2₁/n structure, thereby refuting the reported cubic Fm-3m structure by
G. Huo, et al. Upon optimisation through particle size reduction and carbon coating, the KLaFeMoO₆-K₂MoO₄ composite showed a reversible specific capacity of 46.76 mA h/g over 30 cycles, closely approaching its theoretical capacity
Materials design criteria for ultrahigh thermoelectric power factors in metals
Get PDFFunding: This work has received funding from the UK Research and Innovation fund (project reference EP/X02346X/1) and from the European Union–Next-Generation EU via the Italian call PRIN 2022, project code 2022XZ2ZM8.Metals have high electronic conductivities, but very low Seebeck coefficients, which traditionally make them unsuitable for thermoelectric materials. Recent studies, however, showed that metals could deliver ultrahigh thermoelectric power factors (PFs) under certain conditions. In this work, we theoretically examine the electronic structure and electronic transport specifications that allow for such high PFs. Using Boltzmann transport equation (BTE) simulations and a multiband electronic structure model, we show that metals with (i) a high degree of transport asymmetry between their bands, (ii) strong interband scattering, and (iii) a large degree of band overlap, can provide ultrahigh power factors. We show that each of these characteristics adds to the steepness of the transport distribution function of the BTE, which allows for an increase of the Seebeck coefficient to sizable values, simultaneously with an increase in the electrical conductivity. This work generalizes the concept that transport asymmetry (i.e., a mixture of energy regions of high and low contributions to the electrical conductivity), through a combination of different band masses, scattering strengths, energy filtering scenarios, etc., can indeed result in very high thermoelectric power factors, even in the absence of a material band gap. Under certain conditions, transport asymmetry can overcompensate for any performance degradation to the PF due to bipolar conduction and the naturally low Seebeck coefficients that otherwise exist in this class of materials.Peer reviewe
Igneous rocks as a viable source of fixed nitrogen to the prebiotic world
Get PDFFunding: This work was financially supported by a NERC Frontiers grant to EES (NE/V010824/1), a NERC IAPETUS DTP studentship to FH (NE/S007431/1), and a NERC Standard Grant to SM (NE/V011383/1).The origin and early evolution of life on Earth and other habitable worlds requires constant supply of ammonic nitrogen (N). Previously proposed abiotic ammonium sources rely on sporadic and heterogeneously distributed high energy processes, such as lightning, subaerial volcanic degassing, or deep sea hydrothermal vents to generate bioavailable nitrogen from atmospheric N2 gas. Here we explore weathering of ammonium contained in felsic igneous rocks as an alternative source. We find that this process could have supplied 108–109 mol yr−1 of bioavailable N to surface environments in the early Archean, leading to dissolved concentrations of 0.023 ± 0.017 μM in freshwater and 0.01–0.1 μM in seawater. In terrestrial settings, evaporation paired with elevated N supplies from locally enriched felsic bedrock may have led to concentrations approaching 1 μM. Rock weathering would thus have constituted a smaller flux than the sum of all proposed high energy sources of fixed N, but with the major benefit that it was reliably present, especially in terrestrial settings. Weathering of differentiated igneous rocks should thus be considered in models of the emergence of life on Earth and beyond.Peer reviewe
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