186 research outputs found
Critical interaction constants for binary gas mixtures for use in the Redlich-Kwong equation of state
In this work, critical interaction constants were used to evaluate the interaction coefficients of the Redlich - Kwong constants for bin-ary gas mixtures. From these constants, the pressure - volume - temperature behavior of the mixtures was calculated using the Redlich - Kwong equation.
The critical interaction constants, T12 and P12 , were evaluated for binary mixtures by solving, simultaneously, two second degree equations relating terminal slopes for critical pressure loci and the mole fractions of the components present. The feasibility of this method was tested by calculating P-V-T data for binary mixtures and comparing this with values obtained using the standard combination rules of Redlich and Kwong.
Solutions to the second degree equations were obtained for 90 % of the systems tested. Where P-V-T data was available to test these constants, however, the combination rules of Redlich and Kwong were found, generally, to give better results
Low Temperature Mechanical Testing of Carbon-Fiber/Epoxy-Resin Composite Materials
The use of cryogenic fuels (liquid oxygen and liquid hydrogen) in current space transportation vehicles, in combination with the proposed use of composite materials in such applications, requires an understanding of how such materials behave at cryogenic temperatures. In this investigation, tensile intralaminar shear tests were performed at room, dry ice, and liquid nitrogen temperatures to evaluate the effect of temperature on the mechanical response of the IM7/8551-7 carbon-fiber/epoxy-resin system. Quasi-isotropic lay-ups were also tested to represent a more realistic lay-up. It was found that the matrix became both increasingly resistant to microcracking and stiffer with decreasing temperature. A marginal increase in matrix shear strength with decreasing temperature was also observed. Temperature did not appear to affect the integrity of the fiber-matrix bond
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Modelling Chablis vintage quality in response to inter-annual variation in weather
Weather during grape production affects wine quality. Changes in the weather in the Chablis region of France and in the quality of Chablis wines (vintage scores) from 1963 to 2018 were analysed. Chablis wine quality improved over this period, with no Poor vintages after 1991. Summer temperature and sunshine duration both increased progressively between 1963 to 2018 with fewer frost days but no linear change detected in precipitation. Chablis vintage score was modelled as a function of mean temperature from April to September (curvilinear relation, maximum score at 16-17 °C), mean minimum temperature in September (an index of cool nights; negative relation), and total rainfall from June to September (negative relation). This simple three-factor model distinguished between Poor and higher-quality Chablis vintages well, but less so between Good and Excellent vintages. Application of the model to different climate change scenarios (assuming current viticultural and oenological practices) suggests that vintage scores will decline (slightly to substantially, dependent upon emissions scenario) by the 2041 to 2070 period. This reduction in quality would, however, be minimised if warming of cool nights is less than currently forecast. The Chablis vintage score model may help identify sites with suitable climates for premium white wine from Chardonnay grapevines in emerging cool climate viticulture regions as well as aid Chablis producers mitigating the effects of climate change
Ecological and genetic correlates of long-term population trends in the Park Grass Experiment
The Park Grass Experiment (PGE) is the longest observed set of experimental plant communities in existence. Although the gross composition of the vegetation was at equilibrium over the 60-yr period from 1920 to 1979, annual records show that individual species exhibited a range of dynamics. We tested two hypotheses to explain why some species initially increased nd why subsequently some of these (the outbreak species) decreased gain. The study was designed around eight phylogenetically ndependent contrasts (PICs), each containing related species with ifferent dynamics. Our first hypothesis was that persistent increasers and utbreakers have higher intrinsic rates of natural increase than ontrol species (species without trends), allowing them to spread hen interspecific competition is reduced by drought. This was tested by measuring establishment and seed production of species in ield experiments, with and without interspecific competition. Seed production in outbreak species responded more strongly to release from interspecific competition than it did in either of the ther groups of species. Our second hypothesis was that outbreak species eventually declined because they lacked the genetic variation ecessary to adapt to the novel habitats to which they had initially spread. We tested this by measuring mating systems and genetic diversity in persistent and outbreak species in the PGE. In seven out of seven PICs tested, the outbreak species was more selfing than its persistent relative. There was a significant positive correlation between outcrossing rate and gene diversity. These results support roles for both ecological and genetic traits in long-term dynamics
Presentations: from Kac-Moody groups to profinite and back
We go back and forth between, on the one hand, presentations of arithmetic
and Kac-Moody groups and, on the other hand, presentations of profinite groups,
deducing along the way new results on both
Eigentheory of Cayley-Dickson algebras
We show how eigentheory clarifies many algebraic properties of Cayley-Dickson
algebras. These notes are intended as background material for those who are
studying this eigentheory more closely.Comment: 17 page
Loneliness and the Emotional Experience of Absence
In this paper, we develop an analysis of the structure and content of loneliness. We argue that this is an emotion of absence-an affective state in which certain social goods are regarded as out of reach for the subject of experience. By surveying the range of social goods that appear to be missing from the lonely person's perspective, we see what it is that can make this emotional condition so subjectively awful for those who undergo it, including the profound sense of being unable to realise oneself, in collaboration with others
Whole exome sequencing identifies genetic variants in inherited thrombocytopenia with secondary qualitative function defects
Inherited thrombocytopenias are a heterogeneous group of disorders characterised
by abnormally low platelet counts which can be associated with abnormal bleeding.
Next generation sequencing has previously been employed in these disorders for the
confirmation of suspected genetic abnormalities, and more recently in the discovery
of novel disease causing genes. However its full potential has not previously been
utilised. Over the past 6 years we have sequenced the exomes from 55 patients,
including 37 index cases and 18 additional family members, all of whom were
recruited to the UK Genotyping and Phenotyping of Platelets study. All patients had
inherited or sustained thrombocytopenia of unknown aetiology with platelet counts
varying from 11-186x109
/L. Of the 51 patients phenotypically tested, 37 (73%), had
an additional secondary qualitative platelet defect. Using whole exome sequencing
analysis we have identified “pathogenic” or “likely pathogenic” variants in 46%
(17/37) of our index patients with thrombocytopenia. In addition, we report variants
of uncertain significance in 12 index cases which include novel candidate genetic
variants in previously unreported genes in four index cases. These results
demonstrate that whole exome sequencing is an efficient method for elucidating
potential pathogenic genetic variants in inherited thrombocytopenia. Whole exome
sequencing also has the added benefit of discovering potentially pathogenic genetic
variants for further study in novel genes not previously implicated in inherited
thrombocytopenia
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