Compressibility effects on the scalar mixing in reacting homogeneous turbulence

The compressibility and heat of reaction influence on the scalar mixing in decaying isotropic turbulence and homogeneous shear flow are examined via data generated by direct numerical simulations (DNS). The reaction is modeled as one-step, exothermic, irreversible and Arrhenius type. For the shear flow simulations, the scalar dissipation rate, as well as the time scale ratio of mechanical to scalar dissipation, are affected by compressibility and reaction. This effect is explained by considering the transport equation for the normalized mixture fraction gradient variance and the relative orientation between the mixture fraction gradient and the eigenvectors of the solenoidal strain rate tensor.Comment: In Turbulent Mixing and Combustion, eds. A. Pollard and S. Candel, Kluwer, 200

Development and implementation of a decision pathway for general practitioners for the management or referral of suspected allergy.

Many patients with suspected allergy are referred to specialist care inappropriately. We aimed to develop and implement an online decision pathway to aid General Practitioners' (GPs) management decisions in suspected allergy. Our study involved 1487 GPs, 3 referral management centres, 5 GP system suppliers, 4 primary care trusts, and 1 specialist allergy clinic. The pathway was implemented by 3/5 GP system suppliers, published to Map of Medicine and on a specialist clinic website. In the first year, the pathway ranked in the top 10/160 local care maps accessed via Map of Medicine and was viewed 900 times. Only 96 GPs registered to use the clinic website. Only 110 (7%) GPs responded to the feedback request, of which 13/110 (12%) had used the pathway; nearly all thought it useful. It was used by referral management centres as explanation of rejected referrals. Alternative approaches to embed its use are required. Significance for public healthOne in three people in the UK are affected by allergies during their lifetime. Early diagnosis and appropriate management can improve quality of life and reduce emergency hospitalisation. However, referring patients to secondary care is costly in terms of time and resources. We developed a pathway algorithm to support General Practitioners' (GPs) allergy management and referral decisions to ensure that all referrals to specialist clinics were appropriate. The study illustrates a real world implementation with lessons for those seeking to improve the primary-secondary care interface, implementing pathways in various formats. In the UK, Map of Medicine seems to be the most used software. We demonstrated the difficulty of reaching GPs to encourage adoption of online decision support and suggest new ways forward by expanding care pathways into more detailed protocols for use directly by patients

The Resilience Factor: What Extension Can Learn from Adolescents Coping with Parental Cancer

Using a developmental systems framework and grounded theory methods, the study reported here describes the psychosocial experiences of late adolescents coping with parental cancer. Results suggest three primary psychosocial developmental influences, including multilevel influences, coping strategies to maintain control, and responses to uncertainty and anticipatory grief. Identity and intimacy were the two most salient psychosocial tasks. The central unifying concept of resilience was the primary psychosocial developmental outcome that resulted from coping with parental cancer during late adolescence. This finding illuminates the need for Extension to expand its focus on positive outcomes that can result from coping with life crises during adolescence

Numerical Study of Vortex Reconnection

With a Biot-Savart model of vortex filaments to provide initial conditions, a finite difference scheme for the incompressible Navier-Stokes equation is used in the region of closest approach of two vortex rings. In the Navier-Stokes solution, we see that the low pressure which develops between the interacting vorticity regions causes the distortion of the initially circular vortex cross section and forces the rearrangement of vorticity on a convective time scale which is much faster than that estimated from viscous transport

Can sand dunes be used to study historic storm events?

Knowing the long-term frequency of high magnitude storm events that cause coastal inundation is critical for present coastal management, especially in the context of rising sea levels and potentially increasing frequency and severity of storm events. Coastal sand dunes may provide a sedimentary archive of past storm events from which long-term frequencies of large storms can be reconstructed. This study uses novel portable optically stimulated luminescence (POSL) profiles from coastal dunes to reconstruct the sedimentary archive of storm and surge activity for Norfolk, UK. Application of POSL profiling with supporting luminescence ages and particle size analysis to coastal dunes provides not only information of dunefield evolution but also on past coastal storms. In this study, seven storm events, two major, were identified from the dune archive spanning the last 140 years. These appear to correspond to historical reports of major storm surges. Dunes appear to be only recording (at least at the sampling resolution used here) the highest storm levels that were associated with significant flooding. As such the approach seems to hold promise to obtain a better understanding of the frequency of large storms by extending the dune archive records further back to times when documentation of storm surges was sparse

Positive Youth Development in the Midst of Coping with Parental Cancer: Implications for Youth Development Research and Practice

Four implications for youth development research and practice resulted from a qualitative study on psychosocial developmental experiences of late adolescents coping with parental cancer during late adolescence. The study employed a developmental systems framework and grounded theory methods. Results suggest three primary psychosocial developmental influences, including multilevel influences (individual, familial, and extrafamilial risk and protective factors), coping strategies to maintain control, and responses to uncertainty and anticipatory grief. The particular combination of risk and protective factors present in participants’ lives resulted in positive outcomes; resilience was the central unifying concept that characterized the primary psychosocial developmental outcomes of each participant. This finding illuminates the need to expand our focus in youth development research and practice to include positive developmental outcomes that can result from coping with life crises during adolescence

Predicting the safety and efficacy of butter therapy to raise tumour pHe: an integrative modelling study

Background: Clinical positron emission tomography imaging has demonstrated the vast majority of human cancers exhibit significantly increased glucose metabolism when compared with adjacent normal tissue, resulting in an acidic tumour microenvironment. Recent studies demonstrated reducing this acidity through systemic buffers significantly inhibits development and growth of metastases in mouse xenografts.\ud \ud Methods: We apply and extend a previously developed mathematical model of blood and tumour buffering to examine the impact of oral administration of bicarbonate buffer in mice, and the potential impact in humans. We recapitulate the experimentally observed tumour pHe effect of buffer therapy, testing a model prediction in vivo in mice. We parameterise the model to humans to determine the translational safety and efficacy, and predict patient subgroups who could have enhanced treatment response, and the most promising combination or alternative buffer therapies.\ud \ud Results: The model predicts a previously unseen potentially dangerous elevation in blood pHe resulting from bicarbonate therapy in mice, which is confirmed by our in vivo experiments. Simulations predict limited efficacy of bicarbonate, especially in humans with more aggressive cancers. We predict buffer therapy would be most effectual: in elderly patients or individuals with renal impairments; in combination with proton production inhibitors (such as dichloroacetate), renal glomular filtration rate inhibitors (such as non-steroidal anti-inflammatory drugs and angiotensin-converting enzyme inhibitors), or with an alternative buffer reagent possessing an optimal pK of 7.1–7.2.\ud \ud Conclusion: Our mathematical model confirms bicarbonate acts as an effective agent to raise tumour pHe, but potentially induces metabolic alkalosis at the high doses necessary for tumour pHe normalisation. We predict use in elderly patients or in combination with proton production inhibitors or buffers with a pK of 7.1–7.2 is most promising

High-Resolution Modeling of Multiscale Transient Phenomena in Turbulent Boundary Layers

High fidelity numerical simulation of wall-bounded turbulence requires physically sound representation of the small scale unsteady processes governing near-wall momentum, heat, and mass transfer. Conventional wall treatments do not capture the diverse multiphysics flow regimes relevant to engineering applications. To obtain a robust yet computationally affordable near-wall submodel for turbulent flow computations, the fine-grained spatial structure and time evolution of the near-wall flow is simulated using a model formulated on a 1D domain corresponding to the wall-normal direction. This approach captures the strong variation of flow properties in the wall-normal direction and the transient interactions between this highly inhomogeneous region and the more nearly homogeneous (at fine scales) flow farther from the wall. The 1D simulation utilizes the One Dimensional Turbulence (ODT) methodology, whose formulation for the present application is described in detail. Demonstrations of ODT performance with regard to aspects of flow physics relevant to near-wall flow modeling are presented. The coupling of ODT to a large eddy simulation (LES) of confined turbulent flow is described, and the performance of the coupled formulation is demonstrated. It is concluded that this formulation has the potential to provide the fidelity needed for engineering applications at an affordable computational cost

Diffusion in Stationary Flow from Mesoscopic Non-equilibrium Thermodynamics

We analyze the diffusion of a Brownian particle in a fluid under stationary flow. By using the scheme of non-equilibrium thermodynamics in phase space, we obtain the Fokker-Planck equation which is compared with others derived from kinetic theory and projector operator techniques. That equation exhibits violation of the fluctuation dissipation-theorem. By implementing the hydrodynamic regime described by the first moments of the non-equilibrium distribution, we find relaxation equations for the diffusion current and pressure tensor, allowing us to arrive at a complete description of the system in the inertial and diffusion regimes. The simplicity and generality of the method we propose, makes it applicable to more complex situations, often encountered in problems of soft condensed matter, in which not only one but more degrees of freedom are coupled to a non-equilibrium bath.Comment: 10 pages, accepted in Phys. Rev.