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Conformal symmetries in special and general relativity.The derivation and interpretation of conformal symmetries and asymptotic conformal symmetries in Minkowski space-time and in some space-times of general relativity.
The central objective of this work is to present an analysis of the
asymptotic conformal Killing vectors in asymptotically-flat space-times
of general relativity. This problem has been examined by two different
methods; in Chapter 5 the asymptotic expansion technique originated by
Newman and Unti [31] leads to a solution for asymptotically-flat spacetimes
which admit an asymptotically shear-free congruence of null
geodesics, and in Chapter 6 the conformal rescaling technique of Penrose
[54] is used both to support the findings of the previous chapter and to
set out a procedure for solution in the general case. It is pointed out
that Penrose's conformal technique is preferable to the use of asymptotic
expansion methods, since it can be established in a rigorous manner
without leading to the possible convergence difficulties associated with
asymptotic expansions.
Since the asymptotic conformal symmetry groups of asymptotically flat
space-times Are generalisations of the conformal group of Minkowski
space-time we devote Chapters 3 and 4 to a study of the flat space case so
that the results of later chapters may receive an interpretation in terms
of familiar concepts. These chapters fulfil a second, equally important,
role in establishing local isomorphisms between the Minkowski-space
conformal group, 90(2,4) and SU(2,2). The SO(2,4) representation has been
used by Kastrup [61] to give a physical interpretation using space-time
gauge transformations. This appears as part of the survey of
interpretative work in Chapter 7. The SU(2,2) representation of the
conformal group has assumed a theoretical prominence in recent years.
through the work of Penrose [9-11] on twistors. In Chapter 4 we establish
contact with twistor ideas by showing that points in Minkowski space-time
correspond to certain complex skew-symmetric rank two tensors on the
SU(2,2) carrier space. These objects are, in Penrose's terminology [91,
simple skew-symmetric twistors of valence
[J.
A particularly interesting aspect of conformal objects in space-time is
explored in Chapter 8, where we extend the work of Geroch [16] on multipole
moments of the Laplace equation in 3-space to the consideration. of
Q tý =0 in Minkowski space-time. This development hinges upon the fact
that multipole moment fields are also conformal Killing tensors.
In the final chapter some elementary applications of the results of
Chapters 3 and 5 are made to cosmological models which have conformal
flatness or asymptotic conformal flatness. In the first class here we
have 'models of the Robertson-Walker type and in the second class we have
the asymptotically-Friedmann universes considered by Hawking [73].University of Bradford Research Studenshi
Mitochondrial variant enrichment from high-throughput single-cell RNA-seq resolves clonal populations
Reconstructing lineage relationships in complex tissues can reveal mechanisms underlying development and disease. Recent methods combine single-cell transcriptomics with mitochondrial DNA variant detection to establish lineage relationships in primary human cells, but are not scalable to interrogate complex tissues. To overcome this limitation, here we develop a technology for high-confidence detection of mitochondrial mutations from high-throughput single-cell RNA-sequencing. We use the new method to identify skewed immune cell expansions in primary human clonal hematopoiesis
Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology
notes: As the primary author, O’Malley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. ‘Macrobe’ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes – the dominant life form on the planet, both now and throughout evolutionary history – will transform some of the philosophy of biology’s standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology – including biofilm formation, chemotaxis, quorum sensing and gene transfer – that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations
Effects of flaxseed oil supplementation on plasma adiponectin levels in dyslipidemic men
Background: Dietary alpha-linolenic acid (ALA) has been associated with reduced risk of development of atherosclerosis. Adiponectin is a hormone specifically secreted by adipocytes and considered to have anti-atherogenic properties. Aim of the study: We examined the effect of increased dietary intake of ALA on plasma concentration of adiponectin. Methods: Thirty-five non-diabetic, dyslipidemic men, 38-71 years old, were randomly allocated to take either 15 ml of flaxseed oil rich in ALA (8.1 g/day; n = 18), or 15 ml of safflower oil per day, containing the equivalent n-6 fatty acid (11.2 g/day linoleic acid, LA; n = 17) (control group). The intervention period lasted for 12 weeks. Results: Plasma levels of adiponectin did not change after the increase in dietary intake of ALA in the flaxseed oil supplementation group, compared to the control group. No changes in body mass index, serum lipid concentrations, LDL density, or plasma TNF-α were found in the flaxseed oil versus the control group. Conclusions: Dietary ALA has no effect on plasma adiponectin concentration in dyslipidemic men. © 2007 Spinger
What Can Crystallographic Orientation Tell Us About Nakhlite Formation?
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