Free vorticity field-boundary layer conversions: Effect of boundary configuration and scale

Progress was made on further flow visualization of vortex-leading edge interaction, in conjunction with characterization of the unsteady pressure field. The range of scale of an elliptical leading edge, relative to the incident primary vortex, was determined. The scale of the incident vortex was characterized in terms of mean shear layer parameters. An overview of the interaction mechanism for the range of thin to thick leading-edges is given. The interaction mechanism corresponding to the case where the incident vortex is above the leading-edge is given for hydrogen bubble wires well upstream of and at the tip of the leading edge. A sample of the instantaneous pressure distribution for the case where the incident vortex dives beneath the edge is presented. The effect of scale of the incident vortex relative to that of the leading-edge was examined. The circulation and length scale of the incident vortices in the street are being characterized

Learning to co-operate: China's multilateral approach to Asian financial co-operation

This study explains the ideational sources of China's proactive multilateral diplomacy towards Asian financial co-operation by employing a learning thesis. Challenging prominent materialist explanations (power-transition thesis, realist balancing thesis and economic utility thesis), this study argues that the collective learning of Chinese policy elites through cognitive dissonance, feedback effects and transnational persuasion explains much of the change in China's relational identity and philosophical beliefs regarding regional co-operation. These prior ideational shifts helped to determine China's behaviour change from its muted opposition to Asian financial co-operation in the 1990s to its active support of regional financial co-operation in the early 2000s, as evidenced in the emergence of the Chiang Mai Initiative, Chinese-Japanese-South Korean trilateral financial co-operation and the Asian Bond Fund Initiative. Chinese learning also suggests that more fundamental changes in China's national preference may make its support for Asian financial co-operation more consistent and stable in the foreseeable future than sceptics might anticipate. Copyright © The China Quarterly 2008.published_or_final_versio

Efficacy of Educational Interventions Targeting Primary Care Providers' Practice Behaviors: an Overview of Published Systematic Reviews

Objectives : Primary care providers (e.g., family physicians, pediatricians, registered nurses, physician assistants, and nurse practitioners) could play a pivotal role in the provision of preventive services, especially for very young children (younger than 3 years old) and population groups with limited access to dental care. Given the current problems with access to dental care among low-income Americans, we contend there is a need to involve nondental primary health care providers in screening for and preventing oral health problems. The objective of this overview is to present findings from systematic reviews on the efficacy of continuing medical education, printed educational material, academic outreach, reminders, and local opinion leaders on the adoption of new knowledge and practices by primary care providers. Methods : A search was conducted using the Cochrane Library and MEDLINE. The search aimed to locate systematic reviews published between January 1988 and March 2003. Two researchers independently extracted data and assessed study quality using a modified version of the QUOROM statement. Results : Eleven systematic reviews were included in this overview. The evidence from the included systematic reviews showed that formal continuing medical education (CME) and distributing educational materials did not effectively change primary care providers' behaviors. There are effective interventions available to increase knowledge and change behaviors of primary care providers, such as small group discussion, interactive workshops, educational outreach visits, and reminders. Conclusion : There is a limited knowledge base on the efficacy of the selected interventions on oral health screening by primary care providers. Considering the potential role of primary care providers in improving oral health of underserved populations, this research area should receive more attention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65255/1/j.1752-7325.2004.tb02747.x.pd

Climate dynamics experiments using a GCM simulations

The study of surface-atmosphere interactions has begun with studies of the effect of altering the ocean and land boundaries. A ten year simulation of global climate using observed sea surface temperature anomalies has begun using the NCAR Community Climate Model (CCM1). The results for low resolution (R15) were computed for the first 8 years of the simulation and compared with the observed surface temperatures and the MSU (Microwave Sounding Unit) observations of tropospheric temperature. A simulation at higher resolution (T42) was done to ascertain the effect of interactive soil hydrology on the system response to an El Nino sea surface temperature perturbation. Initial analysis of this simulations was completed

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016-2017

CONTEXT: Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to understanding the crucial physical processes giving rise to jet formation, as well as to their extraordinary radiation output up to γ-ray energies. AIMS: We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm VLBI polarimetric observations, reaching an unprecedented resolution (∼50 μas). We also investigate the variability and physical processes occurring in the source during the observing period, which coincides with a very active state of the source over the entire electromagnetic spectrum. METHODS: We perform the Faraday rotation analysis using 3 and 7 mm data and we compare the obtained rotation measure (RM) map with the polarization evolution in 7 mm VLBA images. We study the kinematics and variability at 7 mm and infer the physical parameters associated with variability. From the analysis of γ-ray and X-ray data, we compute a minimum Doppler factor value required to explain the observed high-energy emission. RESULTS: Faraday rotation analysis shows a gradient in RM with a maximum value of ∼6 × 104⁴ rad m⁻² and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7 mm EVPA orientation is different when the component is exiting the core or crossing a stationary feature at ∼0.1 mas. The interaction between the superluminal component and a recollimation shock at ∼0.1 mas could have triggered the multi-wavelength flares. The variability Doppler factor associated with such an interaction is large enough to explain the high-energy emission and the remarkable optical flare occurred very close in time.Accepted manuscrip

The F-GAMMA program: Multi-frequency study of Active Galactic Nuclei in the Fermi era. Program description and the first 2.5 years of monitoring

To fully exploit the scientific potential of the Fermi mission, we initiated the F-GAMMA program. Between 2007 and 2015 it was the prime provider of complementary multi-frequency monitoring in the radio regime. We quantify the radio variability of gamma-ray blazars. We investigate its dependence on source class and examine whether the radio variability is related to the gamma-ray loudness. Finally, we assess the validity of a putative correlation between the two bands. The F-GAMMA monitored monthly a sample of about 60 sources at up to twelve radio frequencies between 2.64 and 228.39 GHz. We perform a time series analysis on the first 2.5-year dataset to obtain variability parameters. A maximum likelihood analysis is used to assess the significance of a correlation between radio and gamma-ray fluxes. We present light curves and spectra (coherent within ten days) obtained with the Effelsberg 100-m and IRAM 30-m telescopes. All sources are variable across all frequency bands with amplitudes increasing with frequency up to rest frame frequencies of around 60 - 80 GHz as expected by shock-in-jet models. Compared to FSRQs, BL Lacs show systematically lower variability amplitudes, brightness temperatures and Doppler factors at lower frequencies, while the difference vanishes towards higher ones. The time scales appear similar for the two classes. The distribution of spectral indices appears flatter or more inverted at higher frequencies for BL Lacs. Evolving synchrotron self-absorbed components can naturally account for the observed spectral variability. We find that the Fermi-detected sources show larger variability amplitudes as well as brightness temperatures and Doppler factors, than non-detected ones. Flux densities at 86.2 and 142.3 GHz correlate with 1 GeV fluxes at a significance level better than 3sigma, implying that gamma rays are produced very close to the mm-band emission region.Comment: Accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics (18 pages, 9 figures