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‘Since they can’t put Venezuela in their suitcase, they take mosaic tiles from the Maiquetía airport’ : Carlos Cruz-Diez’s kineticism in the time of migration
Get PDFIn the process of displacement caused by the current political and economic crises in Venezuela, the Caracas airport has become a place of powerful significance. The floor of the Simón Bolívar International Airport in Maiquetía features Additive Colour (1974–1978), a mosaic by Venezuelan artist Carlos Cruz-Diez (1923−2019). This public work has acquired exceptional symbolic meanings of political migration due to traveller rituals, documented in newspapers and on social media. Migrants are taking tiles of the airport floor as personal memory triggers of the democratic Venezuela that commissioned Kinetic art. This article analyses how these airport tiles, and Kineticism more generally, have come to acquire meanings of collective memory and national identity for Venezuelans and explains how and why Cruz-Diez’s work has become an intrinsic part of Venezuelan culture.Peer reviewe
Refining acoustic estimation of fish biomass in the ocean and a lake using broadband sampling and target strength modelling
No full textAcoustic technology has been widely accepted as one of the most efficient methods for underwater biological investigation. The paucity of information on the target strength of fish can curb the understanding of their species composition, biomass and distribution, during acoustic studies. In addition, the limitations, regarding the resolution, of traditional continuous wave (CW) echosounders also restricted the acoustic species classification. In this thesis, the more recent broadband (or frequency modulated, FM) echosounders, which offer better range resolution and signal-to-noise ratio (SNR) than traditional echosounders, were used in research in Lake Victoria, East Africa, and the ocean's mesopelagic zone (200-1000 m depth) in order to tackle several key challenges in these fields.
This PhD project uses a combination of broadband echosounding, theoretical modelling, and horizontal acoustic beaming techniques to address the key challenges surrounding fish biomass estimation in different environments. The main themes of the thesis are: 1) developing a Kirchhoff-ray mode (KRM) TS model for dagaa (Rastrineobola argentea), a key species in Lake Victoria, East Africa, to improve its lake-wide biomass estimates, 2) using a horizontal beaming method to investigate the fish distribution and biomass in shallow water (<10 m depth) of Lake Victoria, to aid the lake-wide fisheries management in Lake Victoria, and 3) improving knowledge of the biomass, species composition, and distribution pattern of fish in mesopelagic layers, and aiding in the development of a lowered echosounder suitable for investigating mesopelagic layers.
Key findings from the TS modelling (Chapter 2) indicate that the swimbladder (which comprises 2.6 to 8.2% of body volume) of dagaa accounts for 65% to 90% of the total backscattering intensity at 120 kHz. The KRM model-informed relationship will lead to a substantial reduction (by ca. 30%) in lake-wide estimated biomass. Shallow water (<10 m depth) surveys in Lake Victoria in the Tanzanian (Chapter 3 and Chapter 4) sector suggest that from 2019 to 2023 fish biomass in these shallow margins ranged from 0.15 to 0.36 million tonnes (MT), which equates to between 9.1% and 22.6% of the fish biomass in the Tanzanian open lake (based on the 2020 lake-wide acoustic survey, that observed fish biomass of 1.6 MT). Avoidance behaviour of fish was observed and can result in a 41.5% reduction in the fish density estimation. GAMM (generalized additive mixed effect model) showed the highest fish densities in the major rainy season (February to April). During the dry season (June to August), shallow-water fish density was lower and more variable between regions. Chapter 5 revealed that mesopelagic populations in Mediterranean waters were predominantly comprised of numerous small fish with low individual biomasses. This differs from the situation in Atlantic waters, which exhibit higher biomass but lower biodiversity. Further, estimated fish abundance from trawl nets, ship-borne echosounders, and DSV (Deep-water Sonar and Visual sampler) indicated that DSV reported higher fish density compared to ship-borne echosounders and trawl nets, by factors of up to 3.04 and 20.85, respectively. This suggests that DSV may be less prone to avoidance and sampling biases than ship-borne echosounders and trawl nets, thereby advocating for the use of DSV in surveying the mesopelagic zone.
The TS modelling and broadband acoustic sampling strategies derived in this PhD serve to advance the field of active acoustic observation and enhance our understanding of underwater biological resources. The consequent results will aid both fisheries and conservation management, which now requires more holistic investigation methods for monitoring and assessing the ecosystem
Political theology and democracy : perspectives from South Asia, West Asia, and North Africa
Get PDFFunding: With thanks to the European Union’s Horizon 2020 research and innovation program under grant agreement No. 853051 for a project on ’India’s politics in its vernaculars’.Peer reviewe
Five new diarylbutyrolactones and sesquilignans from Saussurea medusa and their inhibitory effects on LPS-induced NO production
Get PDFFunding information: This work was supported by the Natural Science Foundation of Qinghai Province (No. 2022-ZJ‑930), and the science and innovation platform for the development and construction of special projects of Key Laboratory of Tibetan Medicine Research of Qinghai Province (No. 2022-ZJ‑Y03).Five new diarylbutyrolactones and sesquilignans (1a/1b−4), including one pair of enantiomers (1a/1b), together with ten known analogues (5−14), were isolated from the whole plants of Saussurea medusa. Compound 1 was found to possess an unusual 7,8'-diarylbutyrolactone lignan structure. Separation by chiral HPLC analysis led to the isolation of one pair of enantiomers, (+)-1a and (−)-1b. The structures of the new compounds were elucidated by extensive spectroscopic data. All compounds, except compounds 5, 7 and 9, were isolated from S. medusa for the first time. Moreover, compounds 1−4, 8 and 10−14 had never been obtained from the genus Saussurea previously. Compounds (+)-1a, 2, 5, 7, and 9−11 were found to inhibit the lipopolysaccharide (LPS)-induced release of NO by RAW264.7 cells with IC50 values ranging from 10.1 ± 1.8 to 41.7 ± 2.1 μM. Molecular docking and iNOS expression experiments were performed to examine the interactions between the active compounds and the iNOS enzyme.Peer reviewe
Beyond the feeling individual : insights from sociology on emotions and embeddedness
Get PDFOrganizational scholars have treated emotions mostly as an individual-level phenomenon, with limited theorisation of emotions as an important component in social embeddedness. In this review essay, we argue for the need for a toolkit to study emotions as an inherently social phenomenon. To do so, we apply insights from sociology that have been under-utilized in management and organization research. We focus on three sociological concepts: collective emotions and social bonds, emotional energy and moral batteries, and emotional capital. We then develop an integrative model of emotional embeddedness to emphasize that emotions are socially constructed and socially authorized. We end the paper by setting out a research agenda for more research in management and organization that is informed by these three concepts.Peer reviewe
Methodology development of high sensitivity pulsed EPR and DNP
Get PDFDynamic nuclear polarisation (DNP) is a process that transfers electron spin polarisation to nuclei and is a technique that has been widely used to improve nuclear magnetic resonance (NMR) sensitivity. This thesis presents the implementation of a DNP extension to a home-built high power pulsed electron paramagnetic resonance (EPR) spectrometer, HiPER, integrated with an
arbitrary waveform generator (AWG), operating at 94 GHz. It describes the use of high-peak power inverting chirped pulses to increase the polarisation gradient of dipolar-coupled electrons, where static cross-effect DNP enhancements of 340 are achieved within 3 seconds at 65 K with a mixture of 4-amino TEMPO and DNP juice. Several other nitroxide radical polarising agents are also investigated and systematic study into the DNP temperature dependence for different polarising agents reveals the impact of spectral diffusion and the molecular structure of polarising agents.
In addition, for the first time at 94 GHz, a comparative study is made of different coherent pulsed solid-effect DNP schemes including XiX, TPPM, and the adiabatic solid-effect. An ENDOR upgrade to the DNP/EPR spectrometer is also described, and preliminary room-temperature ¹H ENDOR and low-temperature ¹⁹F ENDOR experiments presented, where a combined approach involving shaped pulse excitation and data processing at an intermediate frequency in down-conversion for DC suppression yields a threefold enhancement in SNR. Finally, a brief summary to ongoing projects on magnet shimming, transition metal DNP and DNP characterisation for lithium dendrites is provided."This work was supported by the China Scholarship Council (CSC) [grant number: 201906320043]; and the University of St Andrews. Funds acquired for individual research projects encapsulated in this thesis are acknowledged within each respective chapter."--Fundin
The blue problem : OLED stability and degradation mechanism
Get PDFFunding: The authors are grateful to Fluxim AG and EPSRC (grants EP/W015137/1 and EP/W524505/1) for financial support.OLED technology has revolutionized the display industry and is promising for lighting. Despite its maturity, there remain outstanding device and materials challenges to address. Particularly, achieving stable and highly efficient blue OLEDs is still proving to be difficult; the vast array of degradation mechanisms at play, coupled with the precise balance of device parameters needed for blue high-performance OLEDs, creates a unique set of challenges in the quest for a suitably stable yet high-performance device. Here, we discuss recent progress in the understanding of device degradation pathways and provide an overview of possible strategies to increase device lifetimes without a significant efficiency trade-off. Only careful consideration of all variables that go into OLED development, from the choice of materials to a deep understanding of which degradation mechanisms need to be suppressed for the particular structure, can lead to a meaningful positive change toward commercializable blue devices.Peer reviewe
The width of Herschel filaments varies with distance
Get PDFFunding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 851435). R.J.S. gratefully acknowledges an STFC Ernest Rutherford fellowship (grant ST/N00485X/1).Context. Filamentary structures in nearby molecular clouds have been found to exhibit a characteristic width of 0.1 pc, as observed in dust emission. Understanding the origin of this universal width has become a topic of central importance in the study of molecular cloud structure and the early stages of star formation. Aims. We investigate how the recovered widths of filaments depend on the distance from the observer by using previously published results from the Herschel Gould Belt Survey. Methods. We obtained updated estimates on the distances to nearby molecular clouds observed with Herschel by using recent results based on 3D dust extinction mapping and Gaia. We examined the widths of filaments from individual clouds separately, as opposed to treating them as a single population. We used these per-cloud filament widths to search for signs of variation amongst the clouds of the previously published study. Results. We find a significant dependence of the mean per-cloud filament width with distance. The distribution of mean filament widths for nearby clouds is incompatible with that of farther away clouds. The mean per-cloud widths scale with distance approximately as 4−5 times the beam size. We examine the effects of resolution by performing a convergence study of a filament profile in the Herschel image of the Taurus Molecular Cloud. We find that resolution can severely affect the shapes of radial profiles over the observed range of distances. Conclusions. We conclude that the data are inconsistent with 0.1 pc being the universal characteristic width of filaments.Peer reviewe
Mistress of the East, goddess of the West: Aphrodite and the development of ancient Greek erotica
Get PDFMy thesis analyses the interlinked complexities of socially constructed sexualities and the identity of Aphrodite from the Archaic to the late-Classical period in order to reinstate a critical connection between ancient Greek conceptions of sex and the divine embodiment of sexuality. Previous scholarship has examined Aphrodite in isolation from sex and sexuality in the ancient Greek world, frequently focusing on her origins in Cyprus and the Near East and/or examining characteristics of her cults in select poleis. Studies on sexuality in ancient Greece often focus on characteristics of hetero/homosexual relationships and/or gender identity. These separate lines of inquiry have led to a notable gap in current scholarship which fails to consider how the cults and iconographies of the Greek goddess of sex relate to ancient Greek explorations of sex.
Using a viewership model which unites analyses of Aphrodite and of erotica in various ancient Greek media within a common interpretative framework, I demonstrate that developments in Aphrodite’s cult personae and material representations in regions where Aphrodite was prominently worshipped, including Sparta, Corinth, and Athens, are reflected in changes in ancient social ideals related to sexuality and gendered desirability.
The Archaic period cults of an armed Aphrodite reflect the divine dichotomy of love and male-instigated violence, a dichotomy similarly explored in Archaic and early-Classical heroic literature and Athenian sympotic vase paintings. Classical Athenian nuptial vase paintings reflect the Athenian emphasis on Aphrodite’s marriage-related cults during the same period. Praxiteles’s late-Classical Aphrodite of Knidos epitomizes contemporary, changing attitudes towards women’s sexuality and the desirability of the nude female form. By analyzing Aphrodite’s cults and associated iconographies in relation to ancient Greek erotica from the Archaic to late-Classical period in select regions, the various links between the divine embodiment of sexuality and the mortal explorations of sex become evident."This work was supported by the British School at Athens, Knossos Research Centre; the Santander Scholarship and Mobility Support Fund; the Russell Trust Postgraduate Award; the Thomas Wiedemann Memorial Fund; and the School of Classics, University of St. Andrews."--Fundin
Water/oil nanoemulsion-based synthesis of BixSn6-2xSy (0.33 ≤ × ≤ 2.95) semiconductor QDs for efficient photocatalytic degradation of MB dye
Get PDFFunding: Open-access funding is provided by the Science, Technology & Innovation Funding Authority (STDF) in cooperation with the Egyptian Knowledge Bank (EKB). The authors would like to thank the University of St Andrews and the Egyptian Government for funding this work.The development of efficient photocatalysts for the photodegradation of organic dyes in wastewater is highly worthwhile. Herein, the nanoemulsion tactic was utilized to synthesize BixSn6-2xSy (0.33 ≤ x ≤ 2.95) photocatalysts with morphological structures that changed from nanowhiskers to quantum dots (QDs). The optical properties of these materials were examined by UV-visible absorbance spectroscopy and photoluminescence, while Mott-Schottky analysis was utilized to study their electronic properties. BixSn6-2xSy materials exhibit appreciable absorption in the UV-visible light range with a direct band gap that increases from 1.23 to 1.46 eV. Both crystal structure and composition greatly affect the photocatalytic activity of BixSn6-2xSy semiconductors. Among the various synthesized photocatalysts, BiSn4S4.5 can efficiently photodegrade methylene blue dye (MB) in the shortest time under UV-visible light. The photocatalytic activity is positively affected by the change of crystal structure from orthorhombic to cubic symmetry. Based on the Mott-Schottky plots, the flat band potential (Efb) and the semiconductor behavior of the fabricated BixSn6-2xSy nanomaterials were determined. The obtained Efb values for SnS, Bi0.33Sn5.34S5.8, BiSn4S5.5, and Bi2.14Sn1.71S4.7 are -0.18 V, -0.42 V, -0.53 V, and -0.51 V (vs. Ag/AgCl), respectively. The Efb value is clearly shifted towards more negative potential values with increasing the Bi molar ratio (x). However, Bi2.95Sn0.1S4.5 semiconductor was found to be of n-type character, having a positive Efb value of +0.66 V (vs. Ag/AgCl). Photocurrent and EIS responses confirm the high stability and photocatalytic activity of BiSn4S5.5, which also achieves the lowest charge transfer resistance. The modified electronic properties of the BixSn6-2xSy semiconductors significantly improve their photocatalytic activity, rendering them to be promising absorbers for sunlight harvesting applications.Peer reviewe
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