Effect of jet fuel aromatics on in-flame soot distribution and particle morphology in a small-bore compression ignition engine

This study reports the effect of fuel aromatic content on soot particle development inside the cylinder of an optically accessible engine. A custom-made set of fuels of 4%, 14% and 24% aromatic content was carefully studied under pilot-main injection conditions. Time-resolved imaging of cool frame, OH* chemiluminescence signals and soot luminosity were performed to visualise the overall reaction development. Planar laser induced fluorescence imaging of HCHO and incandescence imaging of soot were also performed to obtain detailed understanding of reactions and soot distributions. Soot is analysed at a particle level. Using the thermophoresis-based particle sampling method, soot aggregates were collected from multiple in-bowl locations. The subsequent transmission electron microscope (TEM) imaging of the collected soot particles enables structural analysis of soot particles as well as sub-nano-scale carbon layers. The results showed that the aromatic content has little impact on reactions and flame development among the tested fuels. However, the soot formation starts to occur earlier, and its growth rate is much higher for a higher aromatic fuel. As a result, both the peak soot and remaining soot is measured higher for a higher aromatic fuel. The carbon-layer fringe analysis shows more mature, graphitised structures with higher aromatics at both formation-dominant and oxidation-dominant stages. The most noticeable trend is observed from larger soot aggregates for a higher aromatic fuel while the overall shapes are similar

How partisan politics influence government policies in response to ageing populations

Since old-age programmes mitigate life-course risks that are relevant to individuals across socio-economic groups in ageing societies, all parties have a political incentive to support these initiatives. Nevertheless, pre-existing partisan commitments bind the policy instruments that parties use. Cabinet-level analyses of OECD economies demonstrate that left incumbency relies more on public expenditure than right-wing governments. What is more important is that, in the context of large elderly populations, pension coverage is greater under right-leaning governments, while pension replacement rates are higher in left-leaning governments. This shows that party behaviour related to life course-related policies cannot be explained by the conventional pro-expansion versus the pro-retrenchment partisan politics. Rather, a focus on partisan variation in the use of policy instruments is required.The politics and administration of institutional chang

The influence of the aortic valve angle on the hemodynamic features of the thoracic aorta

Since the first observation of a helical flow pattern in aortic blood flow, the existence of helical blood flow has been found to be associated with various pathological conditions such as bicuspid aortic valve, aortic stenosis, and aortic dilatation. However, an understanding of the development of helical blood flow and its clinical implications are still lacking. In our present study, we hypothesized that the direction and angle of aortic inflow can influence helical flow patterns and related hemodynamic features in the thoracic aorta. Therefore, we investigated the hemodynamic features in the thoracic aorta and various aortic inflow angles using patient-specific vascular phantoms that were generated using a 3D printer and time-resolved, 3D, phase-contrast magnetic resonance imaging (PC-MRI). The results show that the rotational direction and strength of helical blood flow in the thoracic aorta largely vary according to the inflow direction of the aorta, and a higher helical velocity results in higher wall shear stress distributions. In addition, right-handed rotational flow conditions with higher rotational velocities imply a larger total kinetic energy than left-handed rotational flow conditions with lower rotational velocities.115Ysciescopu

Fibrosis Evaluation by Transient Elastography in Patients With Long-Term Sustained HCV Clearance

BACKGROUND: Reversibility of advanced fibrosis after HCV-clearance is an important goal of therapy. OBJECTIVES: Measuring liver stiffness (LS) by transient elastography (TE) might be helpful in this setting. PATIENTS AND METHODS: We evaluated 104 patients with biopsy-proven chronic hepatitis C (CHC) and sustained virological response (SVR) after Peg-Interferon (IFN) plus ribavirin since at least 18 months. HCV-eradication was confirmed searching for serum HCV-RNA (TMA® sensitivity > 5-10 IU/ml). Data from literature reported the best LS cut-off values for different stages of liver fibrosis were 7.1 kPa for Metavir stage 2 (F2), 9.5 kPa for F3 and 12.5 for cirrhosis (F4). RESULTS: TE was not reliable in four SVR obese patients. Metavir-stage of biopsy was F0-1 in 28, F2 in 47, F3 in 17 and F4 in eight patients. The median interval elapsed since achieving SVR was 36 months (range: 18-77, SD¬¬:18). Stratifying patients according to the histological stage assessed before treatment, a clear-cut gradient of LS values was observed from F0-1: median: 3.8 kPa (range: 3.5-4.9) to F2: 4.6 kPa (3.8-6.0), F3: 6.2 kPa (4.8-8.6) and F4: 8.4 kPa (6.2-9.2) (P = 0.001). Overall, 86 patients had lower values of LS than the expected LS values according to Metavir-stage. At multivariate logistic analysis γ-GT and histological steatosis were independently associated with persistence of higher values of LS. CONCLUSION: Long term responders to IFN-based therapies have lower LS values than those who are untreated and still viraemic. High levels of γ-GT and liver steatosis, all markers of insulin resistance, may hamper reduction of liver stiffness after HCV-clearance

Charge disproportionation and the pressure-induced insulator?metal transition in cubic perovskite PbCrO3

The perovskite PbCrO3 is an antiferromagnetic insulator. However, the fundamental interactions leading to the insulating state in this single-valent perovskite are unclear. Moreover, the origin of the unprecedented volume drop observed at a modest pressure of P = 1.6 GPa remains an outstanding problem. We report a variety of in situ pressure measurements including electron transport properties, X-ray absorption spectrum, and crystal structure study by X-ray and neutron diffraction. These studies reveal key information leading to the elucidation of the physics behind the insulating state and the pressure-induced transition. We argue that a charge disproportionation 3Cr4+ → 2Cr3+ + Cr6+ in association with the 6s-p hybridization on the Pb2+ is responsible for the insulating ground state of PbCrO3 at ambient pressure and the charge disproportionation phase is suppressed under pressure to give rise to a metallic phase at high pressure. The model is well supported by density function theory plus the correlation energy U (DFT+U) calculations.Fil: Cheng, Jinguang. University Of Texas At Austin; Estados Unidos. Chinese Academy Of Sciences; República de China. University of Tokyo. Institute for Solid State Physics; JapónFil: Kweon, K. E.. University Of Texas At Austin; Estados UnidosFil: Larregola, Sebastian Alberto. University Of Texas At Austin; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ding, Yang. Argonne National Laboratory; Estados UnidosFil: Shirako, Y.. University Of Texas At Austin; Estados UnidosFil: Marshall, L. G.. University Of Texas At Austin; Estados Unidos. Northeastern University; Estados UnidosFil: Li, Z. Y.. University Of Texas At Austin; Estados UnidosFil: Li, X.. University Of Texas At Austin; Estados UnidosFil: Dos Santos, António M.. Oak Ridge National Laboratory. Quantum Condensed Matter Division; Estados UnidosFil: Suchomel, M. R.. Argonne National Laboratory; Estados UnidosFil: Matsubayashi, K.. University of Tokyo. Institute for Solid State Physics; JapónFil: Uwatoko, Y.. University of Tokyo. Institute for Solid State Physics; JapónFil: Hwang, G. S.. University Of Texas At Austin; Estados UnidosFil: Goodenough, John B.. University Of Texas At Austin; Estados UnidosFil: Zhou, J. S.. University Of Texas At Austin; Estados Unido

Multipole interaction between atoms and their photonic environment

Macroscopic field quantization is presented for a nondispersive photonic dielectric environment, both in the absence and presence of guest atoms. Starting with a minimal-coupling Lagrangian, a careful look at functional derivatives shows how to obtain Maxwell's equations before and after choosing a suitable gauge. A Hamiltonian is derived with a multipolar interaction between the guest atoms and the electromagnetic field. Canonical variables and fields are determined and in particular the field canonically conjugate to the vector potential is identified by functional differentiation as minus the full displacement field. An important result is that inside the dielectric a dipole couples to a field that is neither the (transverse) electric nor the macroscopic displacement field. The dielectric function is different from the bulk dielectric function at the position of the dipole, so that local-field effects must be taken into account.Comment: 17 pages, to be published in Physical Review

Flow Measurements via Two-particle Azimuthal Correlations in Au + Au Collisions at sqrt(s_NN) = 130 GeV

Two particle azimuthal correlation functions are presented for charged hadrons produced in Au + Au collisions at RHIC sqrt(s_NN) = 130 GeV. The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values v_2 show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone, epsilon, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low p_T. A breakdown of this epsilon scaling is observed for charged hadrons with p_T > 1.0 GeV/c for the most central collisions.Comment: 6 pages, RevTeX 3, 4 figures, 307 authors, submitted to Phys. Rev. Lett. on 11 April 2002. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (will be made) publicly available at http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm

Net Charge Fluctuations in Au + Au Interactions at sqrt(s_NN) = 130 GeV

Data from Au + Au interactions at sqrt(s_NN) = 130 GeV, obtained with the PHENIX detector at RHIC, are used to investigate local net charge fluctuations among particles produced near mid-rapidity. According to recent suggestions, such fluctuations may carry information from the Quark Gluon Plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.Comment: 6 pages, RevTeX 3, 3 figures, 307 authors, submitted to Phys. Rev. Lett. on 21 March, 2002. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (will be made) publicly available at http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm

Measurement of the mid-rapidity transverse energy distribution from sNN=130\sqrt{s_{NN}}=130 GeV Au+Au collisions at RHIC

The first measurement of energy produced transverse to the beam direction at RHIC is presented. The mid-rapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that E_T / N_ch remains relatively constant as a function of centrality. The energy density calculated via Bjorken's prescription for the 2% most central Au+Au collisions at sqrt(s_NN)=130 GeV is at least epsilon_Bj = 4.6 GeV/fm^3 which is a factor of 1.6 larger than found at sqrt(s_NN)=17.2 GeV (Pb+Pb at CERN).Comment: 307 authors, 6 pages, 4 figures, 1 table, submitted to PRL 4/18/2001; revised version submitted to PRL 5/24/200