173 research outputs found
The factorisation of finite abelian groups
A famous conjecture of Minkowski, concerning the columnation of space-filling lattices, was first proved by Hajos in 1941 by translating the problem into one involving finite abelian groups. The problem solved by Hajos was one concerning a special type of factorisation of finite abelian groups. In the general problem considered in the thesis no restriction is placed on the nature of the factors. It was originally conjectured by Hajos that in any factorisation; one of the factors must possess a non-trivial subgroup as a factor, However, Hajos himself soon found that not all finite abelian groups possess this property. Those which do were called "good" and those which do not were called "bad" Further contributions to determining those groups which are good and those which are had were made by Redei and de Bruijn. But for groups of many types the problem was left undecided. In this thesis the problem is solved completely for finite abelian groups. A special case of this problem for cyclic groups was shown by de Bruijn to be equivalent to a conjecture of his concerning bases for the sets of integers. This conjecture and a generalisation of it are also shown to be true. It is shown first that a cyclotomic polynomial is irreducible over certain fields of reots of unity. This extension of the well-known result that a eyclotomic polynomial is irreducible over the rational field is basic to the following work and is used frecuently throughout the thesis. A theorem, similer to the theorems of de Bruijn, showing that certain types of groups are had is then proved, then, in the main part of the thesis all the groups not shown to be bad by this theorem or one of the theorems of de Bruijn are shown to be good. Hajos gave a method which, be claimed, would give all factorisations of a good group. However it is shown that a correction is needed in this method and the corrected method is then presented. The final section is concerned with the extension of the results to certain types of infinite abelian groups. Under the restriction that one of the factors shall have only a finite number of elements, similar results to these proved for finite groups are obtained for the generalisations of these groups to the infinite cases
Effects of Tectonics and Large Scale Climatic Changes On the Evolutionary History of \u3ci\u3eHyalomma\u3c/i\u3e ticks
Hyalomma Koch, 1844 are ixodid ticks that infest mammals, birds and reptiles, to which 27 recognized species occur across the Afrotropical, Palearctic and Oriental regions. Despite their medical and veterinary importance, the evolutionary history of the group is enigmatic. To investigate various taxonomic hypotheses based on morphology, and also some of the mechanisms involved in the diversification of the genus, we sequenced and analysed data derived from two mtDNA fragments, three nuclear DNA genes and 47 morphological characters. Bayesian and Parsimony analyses based on the combined data (2242 characters for 84 taxa) provided maximum resolution and strongly supported the monophyly of Hyalomma and the subgenus Euhyalomma Filippova, 1984 (including H. punt Hoogstraal, Kaiser and Pedersen, 1969). A predicted close evolutionary association was found between morphologically similar H. dromedarii Koch, 1844, H. somalicum Tonelli Rondelli, 1935, H. impeltatum Schulze and Schlottke, 1929 and H. punt, and together they form a sister lineage to H. asiaticum Schulze and Schlottke, 1929, H. schulzei Olenev, 1931 and H. scupense Schulze, 1919. Congruent with morphological suggestions, H. anatolicum Koch, 1844, H. excavatum Koch, 1844 and H. lusitanicum Koch, 1844 form a clade and so also H. glabrum Delpy, 1949, H. marginatum Koch, 1844, H. turanicum Pomerantzev, 1946 and H. rufipes Koch, 1844. Wide scale continental sampling revealed cryptic divergences within African H. truncatum Koch, 1844 and H. rufipes and suggested that the taxonomy of these lineages is in need of a revision. The most basal lineages in Hyalomma represent taxa currently confined to Eurasia and molecular clock estimates suggest that members of the genus started to diverge approximately 36.25 million years ago (Mya). The early diversification event coincides well with the collision of the Indian and Eurasian Plates, an event that was also characterized by large scale faunal turnover in the region. Using S-Diva, we also propose that the closure of the Tethyan seaway allowed for the genus to first enter Africa approximately 17.73 Mya. In concert, our data supports the notion that tectonic events and large scale global changes in the environment contributed significantly to produce the rich species diversity currently found in the genus Hyalomma
Written information about individual medicines for consumers.
Medicines are the most common intervention in most health services. As with all treatments, those taking medicines need sufficient information: to enable them to take and use the medicines effectively, to understand the potential harms and benefits, and to allow them to make an informed decision about taking them. Written medicines information, such as a leaflet or provided via the Internet, is an intervention that may meet these purposes
The Tryptophan Hydroxylase Inhibitor LX1031 Shows Clinical Benefit in Patients With Nonconstipating Irritable Bowel Syndrome
Serotonin (5-hydroxytryptamine [5-HT]) has an important role in gastrointestinal function. LX1031 is an oral, locally acting, small molecule inhibitor of tryptophan hydroxylase (TPH). Local inhibition of TPH in the gastrointestinal tract might reduce mucosal production of serotonin (5-HT) and be used to treat patients with nonconstipating irritable bowel syndrome (IBS)
Sotagliflozin, a Dual SGLT1 and SGLT2 Inhibitor, as Adjunct Therapy to Insulin in Type 1 Diabetes
To assess the safety and efficacy of dual sodium–glucose cotransporter (SGLT) 1 and SGLT2 inhibition with sotagliflozin as adjunct therapy to insulin in type 1 diabetes
Sport, genetics and the `natural athlete': The resurgence of racial science
This article explores the ethical implications of recent discussions that naturalize the relationship between race, the body and sport within the frame of genetic science. Many suggestions of a racially distributed genetic basis for athletic ability and performance are strategically posited as a resounding critique of the `politically correct' meta-narratives of established sociological and anthropological forms of explanation that emphasize the social and cultural construction of race. I argue that this use of genetic science in order to describe and explain common-sense impressions of racial physiology and sporting ability is founded on erroneous premises of objectivity and disinterest, and inflates the analytical efficacy of scientific truth claims. I suggest that assertions of a value-free science of racial athletic ability reify race as inherited permanent biological characteristics that produce social hierarchies and are more characteristic of a longer history of `racial science'
An MPER antibody neutralizes HIV-1 using germline features shared among donors.
The membrane-proximal external region (MPER) of HIV-1 envelope glycoprotein (Env) can be targeted by neutralizing antibodies of exceptional breadth. MPER antibodies usually have long, hydrophobic CDRH3s, lack activity as inferred germline precursors, are often from the minor IgG3 subclass, and some are polyreactive, such as 4E10. Here we describe an MPER broadly neutralizing antibody from the major IgG1 subclass, PGZL1, which shares germline V/D-region genes with 4E10, has a shorter CDRH3, and is less polyreactive. A recombinant sublineage variant pan-neutralizes a 130-isolate panel at 1.4 μg/ml (IC50). Notably, a germline revertant with mature CDR3s neutralizes 12% of viruses and still binds MPER after DJ reversion. Crystal structures of lipid-bound PGZL1 variants and cryo-EM reconstruction of an Env-PGZL1 complex reveal how these antibodies recognize MPER and viral membrane. Discovery of common genetic and structural elements among MPER antibodies from different patients suggests that such antibodies could be elicited using carefully designed immunogens
A novel cardiovascular risk stratification model incorporating ECG and heart rate variability for patients presenting to the emergency department with chest pain
Human matrix metalloproteinases: An ubiquitarian class of enzymes involved in several pathological processes
Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes
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