38,535 research outputs found
Core content modules at Leeds Metropolitan University
As part of Leeds Metropolitan Universityâs review of the postgraduate curriculum in 2012â13, Libraries and Learning Innovation (LLI) was asked to lead a project group to create two core content modules for use at Level 7 (Masters level) in Research Practice and Project Management. The rationale for choosing these two areas was the sheer number of modules in these subjects taught across a wide range of disciplines, each of which is currently designed and populated by individual course teams. The group consisted of representatives from the Universityâs Centre for Teaching and Learning, academic staff, learning technologists and academic librarians, and was chaired by the Associate Director of LLI, Wendy Luker
Solving the riddle of codon usage preferences: a test for translational selection
Translational selection is responsible for the unequal usage of synonymous codons in protein coding genes in a wide variety of organisms. It is one of the most subtle and pervasive forces of molecular evolution, yet, establishing the underlying causes for its idiosyncratic behaviour across living kingdoms has proven elusive to researchers over the past 20 years. In this study, a statistical model for measuring translational selection in any given genome is developed, and the test is applied to 126 fully sequenced genomes, ranging from archaea to eukaryotes. It is shown that tRNA gene redundancy and genome size are interacting forces that ultimately determine the action of translational selection, and that an optimal genome size exists for which this kind of selection is maximal. Accordingly, genome size also presents upper and lower boundaries beyond which selection on codon usage is not possible. We propose a model where the coevolution of genome size and tRNA genes explains the observed patterns in translational selection in all living organisms. This model finally unifies our understanding of codon usage across prokaryotes and eukaryotes. Helicobacter pylori, Saccharomyces cerevisiae and Homo sapiens are codon usage paradigms that can be better understood under the proposed model
The Case for Combining a Large Low-Band Very High Frequency Transmitter With Multiple Receiving Arrays for Geospace Research: A Geospace Radar
We argue that combining a highâpower, largeâaperture radar transmitter with several largeâaperture receiving arrays to make a geospace radarâa radar capable of probing nearâEarth space from the upper troposphere through to the solar coronaâwould transform geospace research. We review the emergence of incoherent scatter radar in the 1960s as an agent that unified early, pioneering research in geospace in a common theoretical, experimental, and instrumental framework, and we suggest that a geospace radar would have a similar effect on future developments in space weather research. We then discuss recent developments in radioâarray technology that could be exploited in the development of a geospace radar with new or substantially improved capabilities compared to the radars in use presently. A number of applications for a geospace radar with the new and improved capabilities are reviewed including studies of meteor echoes, mesospheric and stratospheric turbulence, ionospheric flows, plasmaspheric and ionospheric irregularities, and reflection from the solar corona and coronal mass ejections. We conclude with a summary of technical requirements
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Effects of Surface Roughness on the Electrochemical Reduction of CO2 over Cu
We have investigated the role of surface roughening on the CO2 reduction reaction (CO2RR) over Cu. The activity and product selectivity of Cu surfaces roughened by plasma pretreatment in Ar, O2, or N2 were compared with that of electrochemically polished Cu samples. Differences in total and product current densities, the ratio of current densities for HER (the hydrogen evolution reaction) to CO2RR, and the ratio of current densities for C2+ to C1 products depend on the electrochemically active surface and are nearly independent of plasma composition. Theoretical analysis of an electropolished and roughened Cu surface reveals a higher fraction of undercoordinated Cu sites on the roughened surface, sites that bind CO preferentially. Roughened surfaces also contain square sites similar to those on a Cu(100) surface but with neighboring step sites, which adsorb OC-COH, a precursor to C2+ products. These findings explain the increases in the formation of oxygenates and hydrocarbons relative to CO and the ratio of oxygenates to hydrocarbons observed with increasing surface roughness
Associative polynomial functions over bounded distributive lattices
The associativity property, usually defined for binary functions, can be
generalized to functions of a given fixed arity n>=1 as well as to functions of
multiple arities. In this paper, we investigate these two generalizations in
the case of polynomial functions over bounded distributive lattices and present
explicit descriptions of the corresponding associative functions. We also show
that, in this case, both generalizations of associativity are essentially the
same.Comment: Final versio
Foliations on modular curves
It is proved, that a foliation on a modular curve given by the vertical
trajectories of holomorphic differential corresponding to the Hecke eigenform
is either the Strebel foliation or the pseudo-Anosov foliation.Comment: to appear Bulletin of the Brazilian Mathematical Society, New Serie
Hydrodynamics in 1+1 dimensions with gravitational anomalies
The constraints imposed on hydrodynamics by the structure of gauge and
gravitational anomalies are studied in two dimensions. By explicit integration
of the consistent gravitational anomaly, we derive the equilibrium partition
function at second derivative order. This partition function is then used to
compute the parity-violating part of the covariant energy-momentum tensor and
the transport coefficients.Comment: 9 pages, JHEP format.v2; added comments and references, matching
published versio
Characteristics of a crystalline granitic aquifer in north-western Ghana
The groundwater potential of north-western Ghana has been assessed in terms oftransmissivity and specific capacities of the basement aquifers. Data from short-term and constant-discharge pumping tests on 14 boreholes were analysed. The Cooper-Jacob straight line analytical methodwas used to determine the aquifer characteristics. The computed transmissivity values of the aquifers varied significantly from 0.37 to 44.5m2 d-1 ; with their specific capacity values ranging from 1.04 to 56.7 m3 d-1m-1 ⹠The storage coefficient from four observation boreholes indicated that the aquifers were under confined conditions with values in the order of 10-5⹠Total head losses of the boreholes anributed to laminar and turbulent flows ranged from 28 per cent to 84 per cent. The aquifer characteristics confirm that groundwater occurrence is localised, confinedand controlled by the development of secondary porosity. Therefore, to obtain adequate water for sustainable use, groundwater abstraction in the study area should be preceded by extensive geophysical investigations using integrated methods
Verbal abuse in married versus non-married couples: the relationship between perception of acceptability and experience
Verbal abuse can lead to physical abuse if it is not recognized, or is tolerated in one\u27s partner. Participant\u27s perception of the acceptability of verbal abuse (PAVA) was compared to the level of verbal abuse in their own relationship (Conflict Tactics Scales-II). PAVA had a weak positive relationship with the actual occurrence of verbal abuse. PAVA and levels of verbal abuse were highest in very new and more established relationships regardless of relationship status. Males were more accepting of verbal abuse, and reported it less in their relationships. Finally, African American, Hispanic American and Asian American participants reported lower levels of verbal abuse in their relationships. These findings illustrate the complex relationship between the perception and experience of verbal abuse and suggest the need for additional research
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