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Recent glacier change (1965 - 2021) and identification of surge-type glaciers on Severnaya Zemlya, Russian High Arctic
Get PDFGlaciers in the Russian High Arctic are rapidly losing mass due to strong atmospheric and oceanic warming of the Barents-Kara Sea region. However, most studies have concentrated on Novaya Zemlya, despite a 29% acceleration in mass loss on Severnaya Zemlya (SZ) in the past decade (2003-2009 to 2010-2017). Research on SZ has formerly been hindered by its inaccessibility and limited data availability, with long-term trends in glacier change largely unknown. Moreover, records of glacier change on SZ may be complicated by evidence of surging, rather than solely due to climatic perturbations. In this thesis, an assessment of recent glacier change (1965 to 2021) on SZ is presented, along with a new inventory of surge-type glaciers from a high-resolution digital elevation model (Arctic DEM), declassified spy-satellite photography (KH-7/9 Hexagon), and optical satellite imagery (Sentinel 2, ASTER & Landsat 8 & TM). A total of 190 glaciers were mapped at five dates and surveyed for glaciological and geomorphological criteria indicative of former or active surging (e.g., thrust-block moraines and looped medial moraines). The results show that the glacierised area reduced from 17,053 km² in 1965 to 16,275 in 2021 (-778 km²) and retreat rates accelerated post-1997. There is no evidence of summer air temperature warming on northern SZ, with most glacier retreat occurring in the south of SZ where land-terminating glaciers have retreated (some up to 30%), attributed to emerging summer air temperature warming trends. Further north, glacier retreat is attributed to rising ocean temperatures and strong annual atmospheric warming which has likely lengthened the melt season. Additionally, four glaciers are classified as surge-type, seven as likely and nine as possible, comprising 11% of SZ’s glaciers. These glaciers occupy larger basins and are more likely to be marine or lake terminating
Explaining the Paradox of Leader Narcissism – How does Leader Narcissism Interact with Intrapersonal and Contextual Factors?
No full textNarcissism is a personality trait that is associated with an exaggerated preoccupation of the self, lack of empathy, power-striving, and grandiose fantasies. This PhD thesis includes four empirical studies that investigated the intrapersonal and the organizational factors influencing how leader narcissism manifests in attitudes and behaviors. Two empirical chapters, each with two studies, focus on different aspects of leader narcissism. Study 1 (N = 73) and Study 2 (N = 157) in Chapter 2 examine how intrapersonal factors affect trait manifestation. Specifically, I distinguished two subtypes of narcissism – grandiosity and vulnerability – and investigated how they interact with levels of identity, thereby influencing leadership outcomes (abusive supervision, workplace incivility, workplace deviance, and transformational leadership). Levels of identity refers to the extent to which one constructs their self-concept in relation to themselves (individual), and to a group (collective). While the research that was conducted during the peak of the Covid-19 pandemic produced null results, Chapter 2 provides a valuable blueprint for future research that distinguishes leaders’ grandiose and vulnerable narcissism. Chapter 3 investigates the role of organizational factors in affecting how leader narcissism manifests. I studied if the interplay between leader narcissism and motivational climates affects the trust followers have in their leaders (Study 3, N = 546 leaders, 1717 = followers). I focused specifically on performance climates (fostering competition) and mastery climates (fostering cooperation). Study 3 found that there was no direct relationship between leader narcissism and follower trust. However, such a relationship was significant and negative when performance climates were strong rather than weak. Similarly, the relationship between leader narcissism and follower trust was negative and significant when the mastery climates were weak. In addition, a follow-up study provided further insights into the intrapersonal processes: I investigated how narcissistic leaders’ self-enhancement in the agentic and the communal domains was affected by their perceptions of the motivational climates (Study 4a, N = 100; Study 4b, N = 101). The findings showed that different levels of abusive supervision occurred depending on whether leader narcissism interacted with performance or mastery climates, respectively. It was found that higher, rather than lower performance climates triggered narcissistic leaders’ agentic tendencies that resulted in abusive supervision. However, there was no interaction effect between leader narcissism and mastery climates that led to a mediating effect of self-enhancement in the communal domain. Chapter 4 summarizes the studies in this thesis and discusses the implications in relation to future research and management practice
Is there lignin in the Ulva cell wall? A multidisciplinary structural investigation to provide new insights into cell wall evolution and macroscopic complexity in the chlorophyte green seaweeds
Get PDFSeaweeds are not only an integral component of the marine ecosystem via their role in global carbon and sulfur cycles, but also have significant economic value as crops for food and fuel, with certain intertidal seaweeds like the green 'sea lettuce' Ulva (Chlorophyta) appearing as attractive bioenergy feedstocks due to their rapid growth rates and polysaccharide-rich cell wall that can comprise half its total biomass.
Seaweeds have a distinct biochemistry to traditional land plant crops. For example, they lack the phenylpropanoid pathway, a key milestone in land plant evolution that enabled the biosynthesis of the secondary cell wall biopolymer lignin which confers structural support and facilitates water transport in vascular plants.
Despite this, 'lignin-like' fractions are reported in Ulva, and lignin has been found in a coralline red seaweed (Rhodophyta). No alternative pathway for lignin biosynthesis is provided by our current metabolic knowledge, meaning we have limited understanding of how ‘lignin’ arose in seaweeds. Furthermore, the only comprehensive structural investigation into seaweed 'phycolignin' to date has been performed in the coralline reds. Consequently, the presence of an equivalent component in green seaweeds like Ulva is still debatable.
As the primary aim of this thesis, I investigate the identity of the proposed lignin-like fraction of Ulva using confocal microscopy, biochemical assays, and biophysical analysis. To accomplish this, I evaluate the use of a sequential extraction protocol described for charophyte green algae (Streptophyta) to determine which cell wall polysaccharides the proposed structure associates with.
No evidence for lignin-like structures in the Ulva cell wall was identified during this research. Instead, I propose that the previous attributions to lignin in Ulva were misidentifications on account of the limitations of quantification protocols used. Interestingly, a major structural protein component is identified with possible implications for how Ulva mitigates osmotic stress at low tide. The absence of 'phycolignin' in the Ulva cell wall contrary to the lignified coralline seaweeds demonstrates that seaweeds display diverse adaptations to intertidal habitats, and provides support to the current hypothesis that lignin arose convergently in the red lineage, with green seaweeds and land plants sharing a more recent evolutionary history
Machine learning high multiplicity matrix elements for electron-positron and hadron-hadron colliders
Get PDFThe LHC is a large-scale particle collider experiment collecting vast
quantities of experimental data to study the fundamental particles, and forces, of
nature. Theoretical predictions made with the SM can be compared with observables
measured at experiments. These predictions rely on the use of Monte Carlo event
generators to simulate events which demand the evaluation of a matrix element. For
high multiplicity processes this can take up a significant portion of the time spent
simulating an event. In this thesis, we explore the usage of machine learning to
accelerate the evaluation of matrix elements by introducing a factorisation-aware neural
network model. Matrix elements are plagued with singular structures in regions of
phase-space where particles become soft or collinear, however, the behaviour of the
matrix element in these limits is well-understood. By exploiting the factorisation
property of matrix elements in these limits, the model can learn how to best represent
the approximation of the matrix elements as a linear combination of singular
functions. We examine the application of the model to e−e+ annihilation matrix
elements at tree-level and one-loop level, as well as to leading order pp collisions
where the acceleration of event generation is critical for current experiments
Immigrant-background young adults giving accounts of themselves: agentic and dialogic reframing of parental cultural heritage
Get PDFIncreasing research attention has been dedicated to the transfer of cultural resources and practices in immigrant families and the different impacts parental cultural heritage can have on children and young adults who navigate their identities and expectations originating from different cultural influences. This research, however, tends to focus on either specific communities or specific aspects of culture, failing to paint a broader picture of how cultural heritage and identities are constituted, experienced, and narrated by young immigrant-background individuals as they enter adulthood. This thesis draws on a qualitative design that involved reflective journaling, interviewing, and collaborative data analysis conducted with 15 participants from a range of ethnic and economic backgrounds—all 18-29 years old and born in the UK to immigrant parents. On the theoretical level, this research problematises and destabilises the link between cultural heritage, collective identity, and self-identification. Drawing on Judith Butler’s Giving an Account of Oneself, the thesis conceptualises parental cultural heritage as a responsibility and considers the role of agency in negotiating the relationship between the self and culture. It then further explores—aided by Mikhail Bakhtin’s concept of dialogism—immigrant-background individuals’ agentic approaches to reframing cultural heritage and cultural identity through dialogic relations and intersubjectivity. Finally, in critical engagement with Homi Bhabha’s notions of hybridity and agency, immigrant-background individuals’ experiences are contextualised within the workings of society to argue that the agentic and dialogic reframing of cultural heritage has its limits and that experiencing, and giving an account of, cultural hybridity will continue to be difficult unless the prevailing discourse shifts. Beyond its theoretical contribution, this thesis emphasises how discussing the sense of responsibility, agency, and cultural heritage with those experiencing hybrid and migrant-background realities requires innovative methodological approaches to elicit the often unarticulated and tacit narratives and understandings. To address this challenge, the thesis introduces the ‘narrative grounded theory’ approach which marries grounded theory and narrative inquiry to produce methodological tools that encourage participants’ reflectiveness, analytical engagement, and revisiting of their stories on multiple occasions
Rotation curves of mock EAGLE dwarf galaxies vs simulations
Get PDFThe dark matter mass distribution within galaxies has been the subject of extensive studies, leading to the cusp/core problem as one of the main topics of discussion. Mock observations provide a way to bridge the gap between simulations and observations by understanding the source of this discrepancy. In this thesis, we create mock observations of the stellar component of dwarf galaxies from two runs of the EAGLE simulations with different star-formation gas density thresholds, a low threshold (LT) and a high threshold (HT). We use SimSpin to make the observations, and define the observing parameters as those from the MUSE instrument with a redshift of 0.2. The galaxies are observed both with and without atmospheric seeing conditions i.e. a point-spread-function (PSF) convolution of . The kinematics of these galaxies are obtained through GIST, which fits the spectrum of the integral field unit cube and recovers the velocity at each pixel. From the line-of-sight velocity map, we select a slit two pixels wide and recover the rotation curves, which we compare directly with the input EAGLE particle data using a slit of the same size. We find dissimilarities between the two as a result of the fitting routines, which are emphasized by the differences caused by the star formation gas density threshold on the structures of the galaxies. HT galaxies have less ordered rotation which leads to less pronounced absorption lines to be used for the spectrum fit and lower velocities, hence, we find larger discrepancies between the rotation curves at HT than at LT. We attempt different methods of processing one LT galaxy, such as removing the PSF convolution, reducing the signal-to-noise ratio, and changing the spectral template, but the discrepancies remain. In particular, we compare the maximum and the fiducial velocities for the mock observations using the radii from EAGLE and the input EAGLE data and find differences between the two as a result of the choice of radii. In general, the differences between the mocks and EAGLE are not seen across all galaxies, but rather in the sample as a whole. This study demonstrates how we can use instruments such as SimSpin to study the role of observational biases in the study of stellar kinematics
Bank deposits, liquidity management and macroeconomy
Get PDFIn this thesis, we investigate the role of deposits in bank liquidity management and macroeconomy empirically. The
thesis is comprised of three main chapters as follows. This first chapter investigates how banks managed their liquidity during the COVID-19 pandemic. We
evaluate three potential channels banks manage their liquidity: the supply-side through the exercise of market
discipline, the demand-side through internal capital markets, and the balance-sheet channel through unused credit
commitments and wholesale funding. We provide novel empirical evidence on the absence of market discipline
theory and internal capital market theory during the pandemic. Furthermore, it is shown that banks exposed to
higher liquidity risk tend to experience larger deposit outflows and increased their exposure in Fed's liquidity
facilities during the pandemic. The second chapter examines the US tri-party repo market operation by investigating the role of dealer's
riskiness on the repo volume and rate during the post-crisis period (2010:Q2-2019:Q4) and the starting quarter of
the pandemic (2020:Q1). We find the market perception of dealer's risk has negative impact on the reverse repo
amount the dealer undertake. In addition, the second chapter investigates the relationship between bank Liquidity
Mismatch Index (LMI) and the repo volume and rate banks undertake. We provide empirical evidence on LMI has
good explanatory power on both banks' repo volume and rate. Finally, this chapter investigates the role of heterogeneity in deposit rates on predicting the severity of crisis
and output. We show an increase in the heterogeneity has strong predicting power on the future economic
downturns. More importantly, it is found an increase in the heterogeneity in deposit rates coupled with a fragile
financial condition, leads to a more severe crisis. In addition, we show the changes in effective federal funds rate
and deposit rates have significant negative impact on household's consumption and income, and this effect is
heterogeneous among households according to balance sheet positions. This thesis contributes to the ongoing debates on bank liquidity management and the deposits channel of
monetary policy transmission. The findings have important policy implications by showing the unique role of bank
deposits in bank liquidity management and macroeconomy. Our main findings suggest that policy makers should be
aware of the importance of liquidity facilities provided by the Federal Reserve and the repo market, especially
during the liquidity stressed periods, as they are playing an essential role in funding bank's liquidity. Moreover, our
findings relating to households suggest policy makers should aware that the effects on households' consumption
from interest rate changes are heterogeneous among households based on their balance sheet positions
Assembling Single RbCs Molecules with Optical Tweezers
Get PDFOptical tweezer arrays are useful tools for manipulating single atoms and molecules.
An exciting avenue for research with optical tweezers is using the interactions between polar molecules for quantum computation or quantum simulation.
Molecules can be assembled in an optical tweezer array starting from pairs of atoms.
The atoms must be initialised in the relative motional ground state of a common trap.
This work outlines the design of a Raman sideband cooling protocol which is implemented to prepare an 87-Rubidium atom in the motional ground state of an 817 nm tweezer, and a 133-Caesium atom in the motional ground state of a 938 nm tweezer.
The protocol circumvents strong heating and dephasing associated with the trap by operating at lower trap depths and cooling from outside the Lamb-Dicke regime.
By analysing several sources of heating, we design and implement a merging sequence that transfers the Rb atom and the Cs atom to a common trap with minimal motional excitation.
Subsequently, we perform a detailed characterisation of AC Stark shifts caused by the tweezer light, and identify several situations in which the confinement of the atom pair influences their interactions.
Then, we demonstrate the preparation of a molecular bound state after an adiabatic ramp across a magnetic Feshbach resonance.
Measurements of molecular loss rates provide evidence that the atoms are in fact associated during the merging sequence, before the magnetic field ramp.
By preparing a weakly-bound molecule in an optical tweezer, we carry out important steps towards assembling an array of ultracold RbCs molecules in their rovibrational ground states
The Process of Internationalisation: Entry Mode Strategy and International Knowledge Acquisition
No full textThe increase in international business emphasises the need to study international entry strategies. Many studies have endeavoured to develop this field and provide practical guides, but there are still some questions and gaps that are unresolved. This thesis specifically aims to explore firms’ international entry modes and their knowledge acquisition relative to post-entry R&D activities. Considerable research has been done about entry mode decisions – the first step of operating in foreign markets. However, a more comprehensive discussion about entry mode choices is necessary due to the conflicting empirical results and the factors that have been ignored. The thesis combines the two fields that are examined separately in existing studies through a meta-analysis of the entry mode choices associated with the antecedents and outcomes. Based on 1,499 effect sizes from 230 published empirical studies, the thesis examines fifteen antecedents and two post-entry outcomes that are related to two entry mode choices based on resource-based view (RBV) and transaction cost economics (TCE). The two entry mode choices are affected by different antecedents; they have different mediation effects between the antecedents and the outcomes. The antecedents of entry modes may affect the outcomes differently. The complicated direct and indirect effects require more empirical studies connecting antecedents and outcomes in one model.
In addition to the meta-review of entry mode choices, this thesis develops an empirical examination of the R&D investments of multinational enterprises (MNE) after international knowledge acquisition. The analysis focuses on cross-border acquisitions, as they are one of the most important ways to gain knowledge; it explains how the interorganisational knowledge (relative knowledge size and technological overlap) of the acquiring and target firms affects the post-entry R&D intensity. The relationships are examined based on 94 cross-border acquisitions worldwide using the digestibility perspective. The relative knowledge size and the technological overlap both have positive influences on acquirers’ R&D investments. Moreover, the presence of institutional distance has a positive effect on the influence of relative knowledge size but a negative effect on technological overlap influences.
The thesis contributes to international entry strategy by generalising current conflict results and clarifying the ignored relationships. Combining the RBV and the TCE, the thesis strengthens the importance of examining antecedents and outcomes in one model, which extends the knowledge about the mediation effects of entry mode choices. Moreover, the analysis of the interorganisational knowledge in cross-border acquisitions complements the current studies by showing how the asymmetric knowledge between partners affects MNE strategic allocations for R&D investments. By using the digestibility perspective to explain the institutional environments, this study deepens the learning about the influences that international environments have on firms’ digestion of acquired knowledge
Judicial Conduct Regulation Regimes in India and the United Kingdom: A Comparative Study
Get PDFJudicial conduct regulation regimes have a vital role in upholding judicial independence, judicial conduct standards and public trust in the judiciary. However, there is no one right way to regulate judicial conduct. As this thesis underlines, the jurisdictions under study (i.e., England and Wales, Northern Ireland, Scotland, and India) have adopted different approaches to judicial regulation. In India, Scotland, and Northern Ireland, internal mechanisms are primarily responsible for judicial regulation, whereas mostly arm-length bodies carry out similar work in England and Wales. Notwithstanding the structural and functional differences these mechanisms bear, they must administer regulatory protocols fairly and consistently across the judicial hierarchies in the respective jurisdictions. Against this backdrop, the thesis attempts to answer the following question: Do regulatory mechanisms in India and the UK uphold judicial independence and effectively enforce the standards of judicial conduct? As regards India, the thesis draws on empirical data collected from 110 subject experts, whereas it engages in statistical and critical analysis in answering the question in relation to the UK. With respect to India, the study finds that the internal regulatory mechanisms for both higher and subordinate judiciaries do not adequately safeguard judicial independence and that the mechanisms are ineffective in enforcing the standards of judicial conduct. In contrast, the study finds that the regulatory mechanisms in the UK are effective in enforcing the standards of judicial conduct. However, the regulatory architecture in the UK offers inadequate safeguards to (individual and internal) judicial independence. The study concludes that there are notable flaws in the regulatory architecture of India and the UK, particularly in addressing abuses of disciplinary discretion by senior judges, violations of regulatory protocols by first-tier bodies, and the unfair and inconsistent application of regulatory processes by investigative authorities
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