182 research outputs found
Segregation of an intruder in a heated granular dense gas
A recent segregation criterion [V. Garz\'o, Phys. Rev. E \textbf{78},
020301(R) (2008)] based on the thermal diffusion factor of an
intruder in a heated granular gas described by the inelastic Enskog equation is
revisited. The sign of provides a criterion for the transition
between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE).
The present theory incorporates two extra ingredients not accounted for by the
previous theoretical attempt. First, the theory is based upon the second Sonine
approximation to the transport coefficients of the mass flux of intruder.
Second, the dependence of the temperature ratio (intruder temperature over that
of the host granular gas) on the solid volume fraction is taken into account in
the first and second Sonine approximations. In order to check the accuracy of
the Sonine approximation considered, the Enskog equation is also numerically
solved by means of the direct simulation Monte Carlo (DSMC) method to get the
kinetic diffusion coefficient . The comparison between theory and
simulation shows that the second Sonine approximation to yields an
improvement over the first Sonine approximation when the intruder is lighter
than the gas particles in the range of large inelasticity. With respect to the
form of the phase diagrams for the BNE/RBNE transition, the kinetic theory
results for the factor indicate that while the form of these diagrams
depends sensitively on the order of the Sonine approximation considered when
gravity is absent, no significant differences between both Sonine solutions
appear in the opposite limit (gravity dominates the thermal gradient). In the
former case (no gravity), the first Sonine approximation overestimates both the
RBNE region and the influence of dissipation on thermal diffusion segregation.Comment: 9 figures; to be published in Phys. Rev.
Thermal diffusion segregation in granular binary mixtures described by the Enskog equation
Diffusion induced by a thermal gradient in a granular binary mixture is
analyzed in the context of the (inelastic) Enskog equation. Although the Enskog
equation neglects velocity correlations among particles which are about to
collide, it retains spatial correlations arising from volume exclusion effects
and thus it is expected to apply to moderate densities. In the steady state
with gradients only along a given direction, a segregation criterion is
obtained from the thermal diffusion factor measuring the amount of
segregation parallel to the thermal gradient. As expected, the sign of the
factor provides a criterion for the transition between the Brazil-nut
effect (BNE) and the reverse Brazil-nut effect (RBNE) by varying the parameters
of the mixture (masses, sizes, concentration, solid volume fraction, and
coefficients of restitution). The form of the phase diagrams for the BNE/RBNE
transition is illustrated in detail for several systems, with special emphasis
on the significant role played by the inelasticity of collisions. In
particular, an effect already found in dilute gases (segregation in a binary
mixture of identical masses and sizes {\em but} different coefficients of
restitution) is extended to dense systems. A comparison with recent computer
simulation results shows a good qualitative agreement at the level of the
thermal diffusion factor. The present analysis generalizes to arbitrary
concentration previous theoretical results derived in the tracer limit case.Comment: 7 figures, 1 table. To appear in New J. Phys., special issue on
"Granular Segregation
Modernization and Its Discontents
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67022/2/10.1177_000276427702100208.pd
Global microRNA expression profiles in insulin target tissues in a spontaneous rat model of type 2 diabetes
AIMS/HYPOTHESIS: MicroRNAs regulate a broad range of biological mechanisms. To investigate the relationship between microRNA expression and type 2 diabetes, we compared global microRNA expression in insulin target tissues from three inbred rat strains that differ in diabetes susceptibility. METHODS: Using microarrays, we measured the expression of 283 microRNAs in adipose, liver and muscle tissue from hyperglycaemic (Goto-Kakizaki), intermediate glycaemic (Wistar Kyoto) and normoglycaemic (Brown Norway) rats (n = 5 for each strain). Expression was compared across strains and validated using quantitative RT-PCR. Furthermore, microRNA expression variation in adipose tissue was investigated in 3T3-L1 adipocytes exposed to hyperglycaemic conditions. RESULTS: We found 29 significantly differentiated microRNAs (p(adjusted) < 0.05): nine in adipose tissue, 18 in liver and two in muscle. Of these, five microRNAs had expression patterns that correlated with the strain-specific glycaemic phenotype. MiR-222 (p(adjusted) = 0.0005) and miR-27a (p(adjusted) = 0.006) were upregulated in adipose tissue; miR-195 (p(adjusted) = 0.006) and miR-103 (p(adjusted) = 0.04) were upregulated in liver; and miR-10b (p(adjusted) = 0.004) was downregulated in muscle. Exposure of 3T3-L1 adipocytes to increased glucose concentration upregulated the expression of miR-222 (p = 0.008), miR-27a (p = 0.02) and the previously reported miR-29a (p = 0.02). Predicted target genes of these differentially expressed microRNAs are involved in pathways relevant to type 2 diabetes. CONCLUSION: The expression patterns of miR-222, miR-27a, miR-195, miR-103 and miR-10b varied with hyperglycaemia, suggesting a role for these microRNAs in the pathophysiology of type 2 diabetes, as modelled by the Gyoto-Kakizaki rat. We observed similar patterns of expression of miR-222, miR-27a and miR-29a in adipocytes as a response to increased glucose levels, which supports our hypothesis that altered expression of microRNAs accompanies primary events related to the pathogenesis of type 2 diabetes
Grandidierite and pseudomorphs of high quartz in \u27\u27nanogranite\u27\u27 and \u27\u27felsite inclusion\u27\u27 enclosed in garnet in granulite of the Highland Complex, central Sri Lanka
第6回極域科学シンポジウム[OG] 地圏11月16日(月) 国立極地研究所3階セミナー
The Early Royal Society and Visual Culture
Recent studies have fruitfully examined the intersection between early modern science and visual culture by elucidating the functions of images in shaping and disseminating scientific knowledge. Given its rich archival sources, it is possible to extend this line of research in the case of the Royal Society to an examination of attitudes towards images as artefacts –manufactured objects worth commissioning, collecting and studying. Drawing on existing scholarship and material from the Royal Society Archives, I discuss Fellows’ interests in prints, drawings, varnishes, colorants, images made out of unusual materials, and methods of identifying the painter from a painting. Knowledge of production processes of images was important to members of the Royal Society, not only as connoisseurs and collectors, but also as those interested in a Baconian mastery of material processes, including a “history of trades”. Their antiquarian interests led to discussion of painters’ styles, and they gradually developed a visual memorial to an institution through portraits and other visual records.AH/M001938/1 (AHRC
A teoria do desenvolvimento político e a questão da ordem e da estabilidade
O tema do artigo são teorias sobre o desenvolvimento político dos países pobres produzidas nos Estados Unidos que baseiam suas práticas científicas (a investigação, a classificação e a seleção de temas) em uma determinada representação do que definiria esses países. O artigo possui como questão de fundo a compreensão da passagem de uma representação desenvolvimentista e econômica para uma visão mais centrada na estabilidade e na ordem durante a década de 1960. Para tanto, debruça-se, primeiramente, sobre a série Studies in Political Development, do Committe on Comparative Politics. Com esse objeto é possível abarcar de forma privilegiada as transformações pela qual a teoria clássica teve que passar para abarcar o novo tema da instabilidade. Por fim, a análise das obras clássicas de Huntington indica quais são as características da nova representação que emerge. Dois aspectos-chave são investigados: (i) a representação dos países pobres e a relação que se estabelece entre a teoria do desenvolvimento político, a teoria do desenvolvimento econômico e a teoria da modernização; (ii) o significado de desenvolvimento político. A análise das obras indica que, por meio da inserção do tema da instabilidade, a teoria do desenvolvimento político se consolida como campo de estudos relevante e autônomo, uma vez que tal tema permitiu conceituar o seu objeto - desenvolvimento político - e argumentar que ele não poderia ser inteiramente reduzido à modernização social ou econômica
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Relationship between the incidence of type 1 diabetes and maternal enterovirus antibodies: time trends and geographical variation
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