Effect of particle inertia on the turbulence in a suspension

We propose a one-fluid analytical model for a turbulently flowing dilute suspension, based on modified Navier-Stokes equation with a $k$-dependent effective density of suspension, $\rho_ {eff}(k)$, and an additional damping term $\propto \gamma_ p(k)$, representing the fluid-particle friction (described by Stokes law). The statistical description of turbulence within the model is simplified by a modification of the usual closure procedure based on the Richardson-Kolmogorov picture of turbulence with a differential approximation for the energy transfer term. The resulting ordinary differential equation for the energy budget is solved analytically for various important limiting cases and numerically in the general case. In the inertial interval of scales we describe analytically two competing effects: the energy suppression due to the fluid particle friction and the energy enhancement during the cascade process due to decrease of the effective density of the small scale motions. An additional suppression or enhancement of the energy density may occur in the viscous subrange, caused by the variation of the extent of the inertial interval due to the combined effect of the fluid-particle friction and the decrease of the kinematic viscosity of the suspensions. The analytical description of the complicated interplay of these effects supported by numerical calculations is presented. Our findings allow one to rationalize the qualitative picture of the isotropic homogeneous turbulence of dilute suspensions as observed in direct numerical simulations.Comment: 21 pages, 5 figues,included, PRE, submitte

Long Memory Modelling of Inflation with Stochastic Variance and Structural Breaks

We investigate changes in the time series characteristics of postwar U.S. inflation. In a model-based analysis the conditional mean of inflation is specified by a long memory autoregressive fractionally integrated moving average process and the conditional variance is modelled by a stochastic volatility process. We develop a Monte Carlo maximum likelihood method to obtain efficient estimates of the parameters using a monthly data-set of core inflation for which we consider different subsamples of varying size. Based on the new modelling framework and the associated estimation technique, we find remarkable changes in the variance, in the order of integration, in the short memory characteristics and in the volatility of volatility

The Health Systems Funding Platform : is this where we thought we were going?

Background: In March 2009, the Task Force for Innovative International Financing for Health Systems recommended "a health systems funding platform for the Global Fund, GAVI Alliance, the World Bank and others to coordinate, mobilize, streamline and channel the flow of existing and new international resources to support national health strategies." Momentum to establish the Health Systems Funding Platform was swift, with the World Bank convening a Technical Workshop on Health Systems Strengthening (HSS), and serial meetings organized to progress the agenda. Despite its potential significance, there has been little comment in peer-reviewed literature, though some disquiet in the international development community around the scope of the Platform and the capacity of the partners, which appears disproportionate to the available information. Methods: This case study uses documentary analysis, participant observation and 24 in-depth interviews to examine the processes of development and key issues raised by the Platform. Results: The findings show a fluid and volatile process, with debate over whether ongoing engagement in HSS by Global Fund and GAVI represents a dilution of organizational focus, risking ongoing support, or a paradigm shift that facilitates the achievement of targeted objectives, builds systems capacity, and will attract additional resources. Uncertainty in the development of the Platform reflects the flexibility of the recently formed global health initiatives, and the instability of donor commitments, particularly in the current financial climate. But implicit in the conflict is tension between key global stakeholders over defining and ownership of the health systems agenda. Conclusions: The tensions appear to have been resolved through a focus on national planning, applying International Health Partnership principles, though the global financial crisis and key personnel changes may yet alter outcomes. Despite its dynamic evolution, the Platform may offer an incremental path towards increasing integration around health systems, that has not been previously possible

Evaluating Relevance Feedback: An Image Retrieval Interface for Children

Studies on information retrieval for children are not yet\ud common. As young children possess a limited vocabulary\ud and limited intellectual power, they may experience more\ud difficulty in fulfilling their information need than adults.\ud This paper presents an image retrieval user interface that\ud is specifically designed for children. The interface uses relevance feedback and has been evaluated by letting children\ud perform different search tasks. The tasks were performed\ud using two interfaces; a more traditional interface - acting as a control interface - and the relevance feedback interface. \ud One of the remarkable results of this study is that children\ud did not favor relevance feedback controls over traditional\ud navigational controls

Testate amoebae as proxy for water level changes in a brackish tidal marsh

Few studies have examined testate amoebae assemblages of estuarine tidal marshes. This study investigates the possibility of using soil testate amoebae assemblages of a brackish tidal marsh (Scheldt estuary, Belgium) as a proxy for water level changes. On the marsh surface an elevation gradient is sampled to be analyzed for testate amoebae assemblages and sediment characteristics. Further, vegetation, flooding frequency and soil conductivity have been taken into account to explain the testate amoebae species variation. The data reveal that testate amoebae are not able to establish assemblages at the brackish tidal marsh part with flooding frequencies equal to or higher than 36.5%. Further, two separate testate amoebae zones are distinguished based on cluster analysis. The lower zone’s testate amoebae species composition is influenced by the flooding frequency (~ elevation) and particle size, while the species variability in the higher zone is related to the organic content of the soil and particle size. These observations suggest that the ecological meaning of elevation shifts over its range on the brackish tidal marsh. Testate amoeba assemblages in such a brackish habitat show thus a vertical zonation (RMSEP: 0.19 m) that is comparable to the vertical zonation of testate amoebae and other protists on freshwater tidal marshes and salt marshes

Could international compulsory licensing reconcile tiered pricing of pharmaceuticals with the right to health?

BACKGROUND: The heads of the Global Fund and the GAVI Alliance have recently promoted the idea of an international tiered pricing framework for medicines, despite objections from civil society groups who fear that this would reduce the leeway for compulsory licenses and generic competition. This paper explores the extent to which an international tiered pricing framework and the present leeway for compulsory licensing can be reconciled, using the perspective of the right to health as defined in international human rights law. DISCUSSION: We explore the practical feasibility of an international tiered pricing and compulsory licensing framework governed by the World Health Organization. We use two simple benchmarks to compare the relative affordability of medicines for governments - average income and burden of disease - to illustrate how voluntary tiered pricing practice fails to make medicines affordable enough for low and middle income countries (if compared with the financial burden of the same medicines for high income countries), and when and where international compulsory licenses should be issued in order to allow governments to comply with their obligations to realize the right to health. An international tiered pricing and compulsory licensing framework based on average income and burden of disease could ease the tension between governments' human rights obligation to provide medicines and governments' trade obligation to comply with the Agreement on Trade-Related Aspects of Intellectual Property Rights

Correspondence regarding 'Assefa Y, et al., BMC Health Services Research. 2011; 11 (1):81 and 2014; 14(1):45': The Positive-Deviance approach for translating evidence into practice to improve patient retention in HIV care.

The purpose of this correspondence is to describe how the positive-deviance approach can be used to translate evidence into practice, based on successive studies conducted in Ethiopia. In earlier studies, it was identified that retention in antiretroviral treatment care was variable across health facilities; and, seeking compliance across facilities, a framework was developed based on the practices of those positive-deviant health facilities, where performance was noted to be markedly better. It was found that the positive deviance approach was effective in facilitating the transfer of innovative practices (using different mechanisms) from positive-deviant health facilities to negative-deviant health facilities. As a result, the variability in retention in care across health facilities narrowed over time, increasing from 83 to 96% in 2007/8 to 95-97% in 2013/14. In conclusion, the positive-deviance approach is a valuable tool to translate evidence into practice, spread good practices, and help achieving universal health coverage

The Semantics of ΕΝΑΓΩΝΙΟΣ in Greek Literary Criticism

Classics and Classical Civilizatio

APOBEC3G Polymorphism as a Selective Barrier to Cross-Species Transmission and Emergence of Pathogenic SIV and AIDS in a Primate Host

Cellular restriction factors, which render cells intrinsically resistant to viruses, potentially impose genetic barriers to cross-species transmission and emergence of viral pathogens in nature. One such factor is APOBEC3G. To overcome APOBEC3G-mediated restriction, many lentiviruses encode Vif, a protein that targets APOBEC3G for degradation. As with many restriction factor genes, primate APOBEC3G displays strong signatures of positive selection. This is interpreted as evidence that the primate APOBEC3G locus reflects a long-term evolutionary “arms-race” between retroviruses and their primate hosts. Here, we provide direct evidence that APOBEC3G has functioned as a barrier to cross-species transmission, selecting for viral resistance during emergence of the AIDS-causing pathogen SIVmac in captive colonies of Asian macaques in the 1970s. Specifically, we found that rhesus macaques have multiple, functionally distinct APOBEC3G alleles, and that emergence of SIVmac and simian AIDS required adaptation of the virus to evade APOBEC3G-mediated restriction. Our evidence includes the first comparative analysis of APOBEC3G polymorphism and function in both a reservoir and recipient host species (sooty mangabeys and rhesus macaques, respectively), and identification of adaptations unique to Vif proteins of the SIVmac lineage that specifically antagonize rhesus APOBEC3G alleles. By demonstrating that interspecies variation in a known restriction factor selected for viral counter-adaptations in the context of a documented case of cross-species transmission, our results lend strong support to the evolutionary “arms-race” hypothesis. Importantly, our study confirms that APOBEC3G divergence can be a critical determinant of interspecies transmission and emergence of primate lentiviruses, including viruses with the potential to infect and spread in human populations

From international health to global health: how to foster a better dialogue between empirical and normative disciplines.

BACKGROUND: Public health recommendations are usually based on a mixture of empirical evidence and normative arguments: to argue that authorities ought to implement an intervention that has proven effective in improving people's health requires a normative position confirming that the authorities are responsible for improving people's health. While public health (at the national level) is based on a widely accepted normative starting point - namely, that it is the responsibility of the state to improve people's health - there is no widely accepted normative starting point for international health or global health. As global health recommendations may vary depending on the normative starting point one uses, global health research requires a better dialogue between researchers who are trained in empirical disciplines and researchers who are trained in normative disciplines. DISCUSSION: Global health researchers with a background in empirical disciplines seem reluctant to clarify the normative starting point they use, perhaps because normative statements cannot be derived directly from empirical evidence, or because there is a wide gap between present policies and the normative starting point they personally support. Global health researchers with a background in normative disciplines usually do not present their work in ways that help their colleagues with a background in empirical disciplines to distinguish between what is merely personal opinion and professional opinion based on rigorous normative research. If global health researchers with a background in empirical disciplines clarified their normative starting point, their recommendations would become more useful for their colleagues with a background in normative disciplines. If global health researchers who focus on normative issues used adapted qualitative research guidelines to present their results, their findings would be more useful for their colleagues with a background in empirical disciplines. Although a single common paradigm for all scientific disciplines that contribute to global health research may not be possible or desirable, global health researchers with a background in empirical disciplines and global health researchers with a background in normative disciplines could present their 'truths' in ways that would improve dialogue. This paper calls for an exchange of views between global health researchers and editors of medical journals