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Ensuring Access to Safe and Nutritious Food for All Through the Transformation of Food Systems
Annals [...].
Pedometrics: innovation in tropics; Legacy data: how turn it useful?; Advances in soil sensing; Pedometric guidelines to systematic soil surveys.Evento online. Coordenado por: Waldir de Carvalho Junior, Helena Saraiva Koenow Pinheiro, Ricardo Simão Diniz Dalmolin
Early Neanderthal social and behavioural complexity during the Purfleet Interglacial: handaxes in the latest Lower Palaeolithic.
Only a handful of ‘flagship’ sites from the Purfleet Interglacial (Marine Isotope Stage 9, c. 350-290,000 years ago) have been properly examined, but the archaeological succession at the proposed type-site at Purfleet suggests a period of complexity and transition, with three techno-cultural groups represented in Britain. The first was a simple toolkit lacking handaxes (the Clactonian), and
the last a more sophisticated technology presaging the coming Middle Palaeolithic (simple prepared core or proto-Levallois technology). Sandwiched between were Acheulean groups, whose handaxes comprise the great majority of the extant archaeological record of the period – these are the focus of this study. It has previously been suggested that some features of the Acheulean in the Purfleet Interglacial were chronologically restricted, particularly the co-occurrence of ficrons and cleavers. These distinctive forms may have exceeded pure functionality and were perhaps imbued with a deeper social and cultural meaning. This study supports both the previously suggested preference for narrow, pointed morphologies, and the chronologically restricted pairing of ficrons and cleavers. By drawing on a wide spatial and temporal range of sites these patterns could be identified beyond the handful of ‘flagship’ sites
previously studied. Hypertrophic ‘giants’ have now also been identified as a chronologically restricted form. Greater metrical variability was found than had been anticipated, leading to the creation of two new sub-groups (IA and IB) which are tentatively suggested to represent spatial and
perhaps temporal patterning. The picture in the far west of Britain remains unclear, but the possibility of different Acheulean groups operating in the Solent area, and a late survival of the Acheulean, are both suggested. Handaxes with backing and macroscopic asymmetry may represent prehensile or ergonomic considerations not commonly found on handaxes from earlier interglacial periods. It is argued that these forms anticipate similar developments in the Late Middle Palaeolithic in an example of convergent evolution
SYSTEMS METHODS FOR ANALYSIS OF HETEROGENEOUS GLIOBLASTOMA DATASETS TOWARDS ELUCIDATION OF INTER-TUMOURAL RESISTANCE PATHWAYS AND NEW THERAPEUTIC TARGETS
In this PhD thesis is described an endeavour to compile litterature about Glioblastoma key molecular mechanisms into a directed network followin Disease Maps standards, analyse its topology and compare results with quantitative analysis of multi-omics datasets in order to investigate Glioblastoma resistance mechanisms. The work also integrated implementation of Data Management good practices and procedures
Synthesis of new high-pressure A-site manganite perovskites and investigation of their magnetic properties
Perovskites, with the general formula, ABO3, have been extensively studied due to their large
variety of intriguing electronic and magnetic properties, which can be achieved via a number
of possible chemical compositions. The use of A and B site cations of various sizes and charges
induce cation order, giving rise to A2BB’O6 and AA’B2O6 double perovskites (DPv), while,
the combination of cation order into both sublattices in an AA’BB’O6 double double perovskite
(DDPv) is uncommon. However, the well-known DDPv arrangement in A and B-sites is a
layered arrangement of A and A’, which coexists with the rock-salt motif of B and B’. The A-site is usually occupied by a large cation with 12-fold coordination, but it can host smaller
cations comparable in size to B-site cations as it becomes distorted (e.g. larger tilt angles). The
smaller the ionic radius of A, the higher the distortion, and higher pressure is required to
stabilise the structure. Employing the formula A= Mn2+ demonstrates some significant
structural features and magnetic properties. An attempt has been made to synthesise new DPv
and DDPv materials, which contain Mn2+, into the A-site to enhance the physical properties of
the material. Three different compounds were successfully synthesised: Mn2NiReO6,
CaMnCrSbO6 and CaMnMnWO6.
Firstly, Mn2NiReO6 is a new member of the ´all transition metal’ (ATM) double perovskite
family and is obtained under high pressure (8 GPa) and high temperature (1573 K) conditions.
The crystal structure was confirmed by PXRD and NPD, with monoclinic P21/n symmetry,
which shows fully ordered Ni2+ and Re6+ within the octahedral sites in a rock-salt motif and a
large distortion, with the greatest tilt angles observed to date, in A-site manganite double
perovskite oxides. Magnetic structure refinement indicates that all moments are ordered
antiferromagnetically below TM1 = 80 K. However, the unusual continuous spin rotation of Mn
spins occur down to a second transition (TM2 = 42 K). This effect has not been reported in any
of the previous Mn2BB’O6 compounds.
Secondly, CaMnCrSbO6 was synthesised under high pressure (10 GPa) and high temperature
(1373 K) conditions. The compound crystallises via PXRD and NPD with a DDPv structure,
which combines columnar order in the A-site cations (Ca and Mn) and rock-salt order of the
B-site cations (Cr and Sb). The Mn in the A and A` sites show alternating square planar and
tetrahedral coordination. CaMnCrSbO6 has a single magnetic transition at 49 K, where Mn2+
and Cr3+ spin order into antiparallel FM sublattices.
Finally, CaMnMnWO6 crystallises via PXRD and NPD at 10 GPa with the monoclinic P21/n
space group in a DPv structure with rock-salt order of the B sites at a high temperature (1573
K). While at a lower temperature (1273 K), a DDPv structure with the P42/n space group is
observed with A-site cations ordered in the columnar order and B-site cations in the rock salt
environment. The magnetic refinement reveals a spin glass behaviour for the DPv structure,
whereas, the DDPv magnetic structure shows antiferromagnetic coupling between
ferromagnetic sublattices at TC = 45 K
A Cornish palimpsest : Peter Lanyon and the construction of a new landscape, 1938-1964
The thesis examines the emergence of Peter Lanyon as one of the few truly innovative British landscape painters this century. In the Introduction I discuss the problematic nature of landscape art and consider the significance of Lanyon's discovery that direct description and linear perspective can be replaced with allusive representational elements by fusing the emotional and imaginative life of the artist with the physical activity of painting. Chapter One concentrates on the period 1936-8 when Lanyon was taught by Borlase Smart, a key figure in the St Ives art colony between the wars. Chapter Two examines the influence of Adrian Stokes and the links between Lanyon's painting and the theories developed in books such as Colour and Form and The Quattro Cento. Chapter Three analyses the period 1940-45 when Lanyon was directly influenced by the constructivism of Nicholson, Hepworth and Gabo. I look closely at their approaches to abstraction and assess Lanyon's relative position to them. The importance of Neo-Romanticism and the status of St Ives as a perceived avant-garde community is also addressed. In Chapter Four I discuss how Lanyon resolved to achieve a new orientation in his art on his return from wartime service with the RAF by synthesising constructivism, and traditional landscape. The Generation and Surfacing Series demonstrate his preoccupation with a sense of place, a fascination with the relationships between the human body and landscape and his struggle to find a technique and style that was entirely his own. His sense of existential insideness is discussed in Chapter Five through an examination of the work derived from Portreath, St. Just and Porthleven - key places in Lanyon's psychological attachment to the landscape of West Penwith. In Chapter Six I examine Lanyon's attachment to myths and archetypal forms, tracing the influence of Bergson's vitalist philosophy as well as his use of Celtic and classical motifs. Chapter Seven is a discussion of the malaise evident in Lanyon's work by 1955 and the impact of American Abstract Expressionism at the Tate Gallery a year later. In the summer of 1959 Lanyon joined the Cornish Gliding Club and Chapter Eight looks at how this necessitated a dynamic, expanded conception of the landscape and a re-thinking of relations within the picture field. The ability to dissolve boundaries encouraged him to break down distinctions between painting and construction so that abstract sculptural elements were now assembled into independent works of art. Finally, Chapter Nine assesses Lanyon's overall position in relation to his early influences and to St Ives art as a whole, his response to new directions in art coming out of London and NewYork in the early 1960s and the importance of travel as a stimulus for further realignment in his artistic and topographical horizons. His pictorial inventiveness and vitality remained unabated at the time of his death and would undoubtedly have continued to be enriched by travel abroad and contact with new movements in modem art on both sides of the Atlanti
Resilience of power grids and other supply networks: structural stability, cascading failures and optimal topologies
The consequences of the climate crisis are already present and can be expected to become more severe in the future. To mitigate long-term consequences, a major part of the world's countries has committed to limit the temperature rise via the Paris Agreement in the year 2015. To achieve this goal, the energy production needs to decarbonise, which results in fundamental changes in many societal aspects. In particular, the electrical power production is shifting from fossil fuels to renewable energy sources to limit greenhouse gas emissions.
The electrical power transmission grid plays a crucial role in this transformation. Notably, the storage and long-distance transport of electrical power becomes increasingly important, since variable renewable energy sources (VRES) are subjected to external factors such as weather conditions and their power production is therefore regionally and temporally diverse. As a result, the transmission grid experiences higher loadings and bottlenecks appear. In a highly-loaded grid, a single transmission line or generator outage can trigger overloads on other components via flow rerouting. These may in turn trigger additional rerouting and overloads, until, finally, parts of the grid become disconnected. Such cascading failures can result in large-scale power blackouts, which bear enormous risks, as almost all infrastructures and economic activities depend on a reliable supply of electric power. Thus, it is essential to understand how networks react to local failures, how flow is rerouted after failures and how cascades emerge and spread in different power transmission grids to ensure a stable power grid operation.
In this thesis, I examine how the network topology shapes the resilience of power grids and other supply networks. First, I analyse how flow is rerouted after the failure of a single or a few links and derive mathematically rigorous results on the decay of flow changes with different network-based distance measures. Furthermore, I demonstrate that the impact of single link failures follows a universal statistics throughout different topologies and introduce a stochastic model for cascading failures that incorporates crucial aspects of flow redistribution. Based on this improved understanding of link failures, I propose network modifications that attenuate or completely suppress the impact of link failures in parts of the network and thereby significantly reduce the risk of cascading failures. In a next step, I compare the topological characteristics of different kinds of supply networks to analyse how the trade-off between efficiency and resilience determines the structure of optimal supply networks. Finally, I examine what shapes the risk of incurring large scale cascading failures in a realistic power system model to assess the effects of the energy transition in Europe
Stability, Electronic Structure, and Nonlinear Optical Properties in Clusters and Materials: A Synergistic Experimental-Computational Analysis
The main objective of Chemistry as a science is an understanding of how and why certain atoms are bonded together and what effects these bonds cause. Modern computational chemistry offers a wide range of tools that greatly assist the exploration of vast chemical space replacing expensive trial-and-error experimental approaches. Computational chemistry may serve to characterize newly synthesized compounds and provide atomic scale insights inaccessible to experimentalists’ vision. Moreover, predictive power of computational chemistry may be used as a guidance for future experiments and for the rational design of new compounds with desired properties.
This dissertation demonstrates the capabilities of joint experimental and theoretical approaches in the characterization of atomic clusters. Bonding and stability analysis in such systems is crucial for understanding the relations between various atomic-scale changes and resulting alterations in chemical properties. This work also makes use of predictive power of modern theoretical methods to probe new chemical species with peculiar electronic properties. A common thread through the projects presented here has been a rationalization of size-and composition-dependent properties of chemical systems based on the analysis of their electronic structure. An essential part of this dissertation is the deciphering of electronic structure via chemical bonding analysis which helps explain various properties in a chemically intuitive manner
Affinity of Ediacaran skeletal fauna and their environmental context
The Ediacaran-Cambrian boundary (~541 million years ago (Ma)) signifies the start
of the ‘Cambrian Explosion’ of animals, and by 520 Ma most major phyla had emerged.
However, characteristics associated with the Cambrian Explosion, such as motile behaviours
and biomineralisation, originated during the Ediacaran. It is thought that oxygenation is the
key driver of the rise of metabolically costly forms of life. Yet, the drivers behind the
oxygenation of Ediacaran basins are not well known. This thesis contributes to the
understanding of the drivers behind the rise of skeletal animals during the Ediacaran as well
as offering insight into their morphology, affinity and mode of life.
New phosphorus speciation data were collected from siliciclastic samples of the
terminal Ediacaran-Cambrian Nama Group, Namibia (ca. 550-538 Ma), from shelf transects
of the two subbasins in order to determine regional nutrient cycling. This was achieved by
combining redox, nutrient cycling, and biotic distribution and diversity data to understand the
controls behind oxygenation through time. Limited phosphorus cycling, prior to 547 Ma, may
have supported the ferruginous conditions, with possible influence from upwelling from the
deep ocean. However, the reduction in continental run off caused the Nama Basin to transition
from unstable redox conditions to more stable oxic conditions at ~547 Ma with full oxic
conditions across the basin by ~542 Ma. The decrease in recycling of bioavailable phosphorus
into the water column allowed for the development of more stable oxic conditions. This in
turn allowed for the radiation of mobile taxa and biomineralising taxa, both metabolically
costly forms a life, allowing them to inhabit deeper areas of the Nama Basin.
The changing redox conditions determined the availability of habitable areas along
the shelf of the Nama Basin. In oxygenated, or transiently-oxygenated, areas of the shelf
Cloudina was able to form reef-frameworks, often in association with microbial mats. Coeval
Cloudina across the Zaris Subbasin share similar features, such as Cloudina-associated
cements and paired lamina, implying calcification was biologically-controlled where laminae
acted as part of the ‘biomineralisation toolkit’. Cloudina-associated cements may have formed
during life as they form prior to breakage, transportation, and abiotic cement formation.
However, the mineralisation of Cloudina must have been environmentally controlled as
evidenced by the variation of paired lamina thickness and Cloudina wall thickness across the
shelf. The variation in thickness may have been due to physical factors, such as hydrodynamic
energy, or chemical factors, such as seaswater pH.
The affinity of Ediacaran fauna are greatly contested due to the general absence of
preserved diagnostic features and soft tissue. However, this thesis presents new findings of
polytomous branching in cloudinomorphs within the Omkyk Member of the Nama Group.
Polytomous branching is a feature attributed to non-bilaterian taxa and so could suggest that
these cloudinomorphs are of cnidarian origin and are part of a potentially polyphyletic group.
In addition, the discovery of a Lagerstätte within the Omkyk Member shows soft-tissue
preservation of in-situ Namacalathus where a combination of features, such as a U-shaped gut
and organic-rich pores within the skeleton, could suggest a lophotrochazoan affinity. Although
molecular phylogenies predict an older origin, lophotrochozoan fossils were previously known
only from the Early Cambrian and so this discovery provides a potential link between the
Ediacaran and Cambrian biotas
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