| 551. |
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| 552. |
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| 553. |
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| 554. |
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| 555. |
- Ross, Owen A., et al.
(author)
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Association of LRRK2 exonic variants with susceptibility to Parkinson's disease: a case-control study
- 2011
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In: Lancet Neurology. - 1474-4465. ; 10:10, s. 898-908
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Journal article (peer-reviewed)abstract
- Background The leucine-rich repeat kinase 2 gene (LRRK2) harbours highly penetrant mutations that are linked to familial parkinsonism. However, the extent of its polymorphic variability in relation to risk of Parkinson's disease (PD) has not been assessed systematically. We therefore assessed the frequency of LRRK2 exonic variants in individuals with and without PD, to investigate the role of the variants in PD susceptibility. Methods LRRK2 was genotyped in patients with PD and controls from three series (white, Asian, and Arab-Berber) from sites participating in the Genetic Epidemiology of Parkinson's Disease Consortium. Genotyping was done for exonic variants of LRRK2 that were identified through searches of literature and the personal communications of consortium members. Associations with PD were assessed by use of logistic regression models. For variants that had a minor allele frequency of 0.5% or greater, single variant associations were assessed, whereas for rarer variants information was collapsed across variants. Findings 121 exonic LRRK2 variants were assessed in 15 540 individuals: 6995 white patients with PD and 5595 controls, 1376 Asian patients and 962 controls, and 240 Arab-Berber patients and 372 controls. After exclusion of carriers of known pathogenic mutations, new independent risk associations were identified for polymorphic variants in white individuals (M1646T, odds ratio 1.43, 95% CI 1.15-1.78; p=0.0012) and Asian individuals (A419V, 2.27, 1.35-3.83; p=0.0011). A protective haplotype (N551K-R1398H-K1423K) was noted at a frequency greater than 5% in the white and Asian series, with a similar finding in the Arab-Berber series (combined odds ratio 0.82, 0.72-0.94; p=0.0043). Of the two previously reported Asian risk variants, G2385R was associated with disease (1.73, 1.20-2.49; p=0.0026), but no association was noted for R1628P (0.62, 0.36-1.07; p=0.087). In the Arab-Berber series, Y2189C showed potential evidence of risk association with PD (4.48, 133-15.09; p=0.012). Interpretation The results for LRRK2 show that several rare and common genetic variants in the same gene can have independent effects on disease risk. LRRK2, and the pathway in which it functions, is important in the cause and pathogenesis of PD in a greater proportion of patients with this disease than previously believed. These results will help discriminate those patients who will benefit most from therapies targeted at LRRK2 pathogenic activity. Funding Michael J Fox Foundation and National Institutes of Health.
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| 556. |
- Ross, Russell G., et al.
(author)
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Clathrate and other solid phases in the tetrahydrofuran–water system : thermal conductivity and heat capacity under pressure
- 1982
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In: Canadian journal of chemistry (Print). - : Canadian Science Publishing. - 0008-4042 .- 1480-3291. ; 60:7, s. 881-892
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Journal article (peer-reviewed)abstract
- Solid phases in the tetrahydrofuran–water (THF–H2O) system were investigated in the temperature range 100–260 K and at pressures up to 1.5 GPa. Thermal conductivity, λ, and heat capacity per unit volume, ρcp, were measured, using the transient hot-wire method. We made measurements on solid phases having nominal compositions THF•17H2O, THF•7.1H2O, and THF•4.6H2O, which we refer to as phases α, β, and γ, respectively. Phase α is known to be a structure II clathrate hydrate, and λ for this phase was found to be similar to other crystalline solids which are glass-like in relation to their thermal properties. Low-energy excitations are known to be relevant to the properties of glass-like solids, and, in the case of phase α, were probably rotational vibrations of the THF guest molecules. Phase β was similar, and we inferred that it was probably a structure I clathrate hydrate. Phase γ behaved nearly like a normal crystal phase at low temperatures, but λ became almost independent of temperature near melting. At 1.1 GPa and 130 K, we found evidence that phase α transformed, on pressurization, to a metastable modification which may be a new high-density form of clathrate hydrate. The astrophysical implications of our results were mentioned briefly.
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| 557. |
- Ross, Russell G.
(author)
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Equation of state and transport properties of solids
- 1986
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In: Physica B+C. - : Elsevier. - 0378-4363. ; 139-140, s. 153-158
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Journal article (peer-reviewed)abstract
- Methods for measuring both the equation of state and the thermal conductivity of solids under pressure are briefly reviewed. The equation of state is shown to be of considerable importance in analysing data for thermal conductivity, using the alkali halides for purposes of illustration.
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| 558. |
- Ross, Russell G.
(author)
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New dimensions in the study of phonon thermal conductivity through the use of high pressure
- 1982
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In: High Pressure in Research and Industry. ; , s. 95-107
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Conference paper (peer-reviewed)abstract
- High pressure is a powerful variable in investigating heat transfer in nonmetallic solids. The effects of phase transitions, and density changes generally, can now be studied using several different techniques of adequate accuracy. Only temperatures > the Debye temperature are considered. Solids for which data are available include relatively simple solids like the alkali and silver halides, as well as many more-complex molecular solids. For the latter, the effects of various forms of structural disorder is a recurrent theme, which can be illustrated by means of solids such as high pressure ices, ammonium chloride, plastic crystal phases and clathrate hydrates.
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| 559. |
- Ross, Russell G.
(author)
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Predicting the equation of state of condensed materials through use of low-pressure expansion and room-temperature compression data
- 1992
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In: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 53:7, s. 857-864
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Journal article (peer-reviewed)abstract
- Empirical prediction of the equation of state (EOS) over an area in pressure-temperature (p-T) space was attempted using primary data for low-pressure (p0) expansion and room-temperature (T0) compression together with various ansatz to effectively restrict the functional form which the EOS could have. Tests against experimental data for the EOS of a variety of substances at p-T co-ordinates which were not on the p0 isobar or T0 isotherm showed that some ansatz could successfully predict the EOS at a general p-T co-ordinate which was within the ranges of the primary data. However, success rate in prediction was only at about the 50% level and furthermore no systematics were detected which would enable prior selection of the appropriate ansatz to be applied to a specific substance. Theoretical models for the EOS which include a general assumption of one of the ansatz under consideration were therefore shown to be lacking in empirical justification. It was concluded that at present reliable knowledge of the EOS over an area in p-T space can only be obtained through direct experimental determination.
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| 560. |
- Ross, Russell G.
(author)
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Thermal conductivity and disorder in nonmetallic materials
- 1991
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In: Physics and chemistry of liquids (Print). - : Taylor & Francis. - 0031-9104 .- 1029-0451. ; 23:4, s. 189-210
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Journal article (peer-reviewed)abstract
- Experimental results for thermal conductivity λ are presented and discussed for a range of nonmetallic materials. Disorder, involving both static and dynamic aspects, is covered over a range from well-ordered solids to glasses. Amongst intermediately-disordered (ID) solids which are considered the cases of plastic crystal phases, the glassy crystal state, inclusion compounds and chiral substances receive detailed attention. Emphasis is given to relatively-high temperature (T) where results for λ of glasses and ID solids are shown to be similar. It is demonstrated how data for λ(T) which have been measured under isobaric conditions can be transformed to isochoric conditions, and this transformation is shown to be important for purposes of analysis of results. Limitations at high temperature of the phonon picture of heat transport are explored using an empirical approach and an alternative picture involving hopping of localized vibrational excitations is also briefly discussed.
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