3,811 research outputs found
M. Hastings, Halluin la Rouge 1919-1939. Aspects d'un communisme identitaire ; J.-P. Molinari, Les ouvriers communistes. Sociologie de l'adhésion ouvrière au PCF
No full textLazar Marc. M. Hastings, Halluin la Rouge 1919-1939. Aspects d'un communisme identitaire ; J.-P. Molinari, Les ouvriers communistes. Sociologie de l'adhésion ouvrière au PCF. In: Politix, vol. 5, n°20, Quatrième trimestre 1992. L'ordre parlementaire, sous la direction de Bastien François, Brigitte Gaïti et Jean-Philippe Heurtin. pp. 179-184
Symmetric Normal Mixture GARCH
No full textNormal mixture (NM) GARCH models are better able to account for leptokurtosis in financial data and offer a more intuitive and tractable framework for risk analysis and option pricing than student’s t-GARCH models. We present a general, symmetric parameterisation for NM-GARCH(1,1) models, derive the analytic derivatives for the maximum likelihood estimation of the model parameters and their standard errors and compute the moments of the error term. Also, we formulate specific conditions on the model parameters to ensure positive, finite conditional and unconditional second and fourth moments. Simulations quantify the potential bias and inefficiency of parameter estimates as a function of the mixing law. We show that there is a serious bias on parameter estimates for volatility components having very low weight in the mixing law. An empirical application uses moment specification tests and information criteria to determine the optimal number of normal densities in the mixture. For daily returns on three US Dollar foreign exchange rates (British pound, euro and Japanese yen) we find that, whilst normal GARCH(1,1) models fail the moment tests, a simple mixture of two normal densities is sufficient to capture the conditional excess kurtosis in the data. According to our chosen criteria, and given our simulation results, we conclude that a two regime symmetric NM-GARCH model, which quantifies volatility corresponding to ‘normal’ and ‘exceptional’ market circumstances, is optimal for these exchange rate data.Volatility regimes, conditional excess kurtosis, normal mixture, heavy trails, exchange rates, conditional heteroscedasticity, GARCH models.
Highly selective aqueous phase selective hydrogenation of phenols over RuO2 nanoparticles supported on MCM-41
No full textSelective aqueous phase hydrogenation of phenol as well as its derivatives is important for the synthesis of chemical intermediates which are crucial for the manufacture of high-tonnage commodities and a multitude of value added platform chemicals. Herein, we report a facile catalyst made of highly dispersed small RuO2 nanoparticles supported on mesoporous MCM-41 using one-pot approach. The optimal 5RuO2-MCM-41 catalyst with particle size 6-8 nm showed excellent activity and selectivity in aqueous phase hydrogenation of phenol and other functionalized substrates, which are building blocks of lignin, to corresponding cyclohexanol products without any additives. These catalysts showed better stability and can be reused several times without any significant drop in activity which proves the heterogeneity of the immobilized oxide catalyst
HAT-P-32b AND HAT-P-33b: TWO HIGHLY INFLATED HOT JUPITERS TRANSITING HIGH-JITTER STARS
No full textWe report the discovery of two exoplanets transiting high-jitter stars. HAT-P-32b orbits the bright V = 11.289 late-F-early-G dwarf star GSC 3281-00800, with a period P = 2.150008 +/- 0.000001 d. The stellar and planetary masses and radii depend on the eccentricity of the system, which is poorly constrained due to the high-velocity jitter (similar to 80 m s(-1)). Assuming a circular orbit, the star has a mass of 1.16 +/- 0.04 M-circle dot and radius of 1.22 +/- 0.02 R-circle dot, while the planet has a mass of 0.860 +/- 0.164 M-J and a radius of 1.789 +/- 0.025 R-J. The second planet, HAT-P-33b, orbits the bright V = 11.188 late-F dwarf star GSC 2461-00988, with a period P = 3.474474 +/- 0.000001 d. As for HAT-P-32, the stellar and planetary masses and radii of HAT-P-33 depend on the eccentricity, which is poorly constrained due to the high jitter (similar to 50 m s(-1)). In this case, spectral line bisector spans (BSs) are significantly anti-correlated with the radial velocity residuals, and we are able to use this correlation to reduce the residual rms to similar to 35ms(-1). We find that the star has a mass of 1.38 +/- 0.04 M-circle dot and a radius of 1.64 +/- 0.03 R-circle dot while the planet has a mass of 0.762 +/- 0.101 M-J and a radius of 1.686 +/- 0.045 R-J for an assumed circular orbit. Due to the large BS variations exhibited by both stars we rely on detailed modeling of the photometric light curves to rule out blend scenarios. Both planets are among the largest radii transiting planets discovered to date
Assessment of circadian rhythms in humans: comparison of real-time fibroblast reporter imaging with plasma melatonin.
No full textWe compared the period of the rhythm of plasma melatonin, driven by the hypothalamic circadian pacemaker, to in vitro periodicity in cultured peripheral fibroblasts to assess the effects on these rhythms of a polymorphism of PER3 (rs57875989), which is associated with sleep timing. In vitro circadian period was determined using luminometry of cultured fibroblasts, in which the expression of firefly luciferase was driven by the promoter of the circadian gene Arntl (Bmal1). The period of the melatonin rhythm was assessed in a 9-d forced desynchrony protocol, minimizing confounding effects of sleep-wake and light-dark cycles on circadian rhythmicity. In vitro periods (32 participants, 24.61±0.33 h, mean±sd) were longer than in vivo periods (31 participants, 24.16±0.17 h; P0.4). Analyses of replicate in vitro assessments demonstrated that circadian period was reproducible within individuals (intraclass correlation=0.62), but in vivo and in vitro period assessments did not correlate (P>0.9). In accordance with circadian entrainment theory, in vivo period correlated with the timing of melatonin (P<0.05) at baseline and with diurnal preference (P<0.05). Individual circadian rhythms can be reliably assessed in fibroblasts but may not correlate with physiological rhythms driven by the central circadian pacemaker.-Hasan, S., Santhi, N., Lazar, A.S., Slak, A., Lo, J., von Schantz, M., Archer, S. N., Johnston, J. D., Dijk, D.-J. Assessment of circadian rhythms in humans: comparison of real-time fibroblast reporter imaging with plasma melatonin
Neutron scattering investigations of spinel ferrimagnets: symmetry and magnetoelastic domain wall patterning
No full textSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2024-12-01The student, Lazar Kish, accepted the attached license on 2022-07-27 at 12:08.The student, Lazar Kish, submitted this Dissertation for approval on 2022-07-27 at 12:28.This Dissertation was approved for publication on 2022-08-08 at 10:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #18437 on 2023-04-12 at 08:09:57The interplay and coupling of distinct order parameters, such as between magnetic order and superconductivity in cuprates or between spin and lattice distortions in type-II multiferroics present some of the most complex problems in condensed matter physics and materials science. Even in situations where the local physics behind such couplings is well described, unexpected behaviors can arise on the mesoscale where local symmetries are broken by defects such as domain-walls, which are ubiquitous features of ordered phases.
My thesis work involves an extended series of neutron and X-ray diffraction and thermodynamic measurements on ferrimagnetic spinel materials (Mn3O4 , MnV2O4 , FeV2O4). These materials are known for strong couplings between spin and lattice degrees of freedom which give rise to giant magnetoelastic and magnetodielectric couplings. Chapter 3 reports on a strain-induced nanoscale patterning of magnetoelastic domain walls in the bulk of single crystals of Mn3O4 and MnV2O4 . The domain-walls are observable using small-angle neutron scattering, which allows us to track their organizational behavior as a function of temperature and applied magnetic field. As I demonstrate with parallel single-crystal neutron diffraction and macroscopic measurements, the response of these domain wall patterns to environmental stress and applied magnetic fields greatly influences the large-scale magnetostrictive and magnetodielectric behaviors. Chapter 4 reports on the discovery of a coherent superstructure modulation in MnV2O4 which develops at the same magnetic transitions as the stripe domains. I will also present my work on the spinel multiferroic FeV2O4 , which has a cascade of low-temperature magnetic and structural transitions. Diffraction results in Chapter 5 imply that the high-temperature space-group of this material may need to be reinterpreted. As Chapter 6 shows, small-angle neutron scattering and neutron diffraction uncover increasingly complex mesoscopic behaviors in this material as symmetries are progressively reduced for each low-temperature phase
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Modelling primary production and environmental thresholds: an example of a UK lowland river
No full textNutrient enrichment and drought conditions are major threats to lowland rivers causing ecosystem degradation and composition changes in plant communities. The controls on primary producer composition in chalk rivers are investigated using a new model and existing data from the River Frome (UK) to explore abiotic and biotic interactions. The growth and interaction of four primary producer functional groups (suspended algae, macrophytes, epiphytes, sediment biofilm) were successfully linked with flow, nutrients (N, P), light and water temperature such that the modelled biomass dynamics of the four groups matched that of the observed. Simulated growth of suspended algae was limited mainly by the residence time of the river rather than in-stream phosphorus concentrations. The simulated growth of the fixed vegetation (macrophytes, epiphytes, sediment biofilm) was overwhelmingly controlled by incoming solar radiation and light attenuation in the water column. Nutrients and grazing have little control when compared to the other physical controls in the simulations. A number of environmental threshold values were identified in the model simulations for the different producer types. The simulation results highlighted the importance of the pelagic–benthic interactions within the River Frome and indicated that process interaction defined the behaviour of the primary producers, rather than a single, dominant driver. The model simulations pose interesting questions to be considered in the next iteration of field- and laboratory-based studie
Chasing coevolutionary signals in intrinsically disordered proteins complexes
No full textIntrinsically disordered proteins/regions (IDPs/IDRs) are crucial components of the cell, they are highly abundant and participate ubiquitously in a wide range of biological functions, such as regulatory processes and cell signaling. Many of their important functions rely on protein interactions, by which they trigger or modulate different pathways. Sequence covariation, a powerful tool for protein contact prediction, has been applied successfully to predict protein structure and to identify protein–protein interactions mostly of globular proteins. IDPs/IDRs also mediate a plethora of protein–protein interactions, highlighting the importance of addressing sequence covariation-based inter-protein contact prediction of this class of proteins. Despite their importance, a systematic approach to analyze the covariation phenomena of intrinsically disordered proteins and their complexes is still missing. Here we carry out a comprehensive critical assessment of coevolution-based contact prediction in IDP/IDR complexes and detail the challenges and possible limitations that emerge from their analysis. We found that the coevolutionary signal is faint in most of the complexes of disordered proteins but positively correlates with the interface size and binding affinity between partners. In addition, we discuss the state-of-art methodology by biological interpretation of the results, formulate evaluation guidelines and suggest future directions of development to the field
A population perspective on mobile phone related tasks
No full textThis paper reports on three mobile phone related tasks carried out by participants in a large scale pilot survey carried out nationally, and in participants homes. The tasks selected represent activities common to mobile phone use, including menu selection styles, pressing small pushbuttons and connecting cables. The results include successful task completion data and subsequent participant ratings of ease of the task. The results are broken down by age and gender, and comparisons are made between tasks. In the paper prototyped menu selection tasks, older participants were considerably less successful than younger participants, although generally both the 'select and confirm' and 'number navigation' interfaces performed badly. In the button pressing tasks, participants fared better with the larger buttons, but the smaller buttons discriminated more against the older participant success rates. Headphone jack plug insertion was less successful than mini-USB plug insertion for most age groups, but was worse for female participants than male. The paper concludes that more research into some of the underlying factors is necessary, but it is clear that current mobile phone designs are failing older users
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