Free Decay of Turbulence and Breakdown of Self-Similarity

It has been generally assumed, since the work of von Karman and Howarth in 1938, that free decay of fully-developed turbulence is self-similar. We present here a simple phenomenological model of the decay of 3D incompressible turbulence, which predicts breakdown of self-similarity for low-wavenumber spectral exponents $n$ in the range $n_c<n<4$, where $n_c$ is some threshold wavenumber. Calculations with the eddy-damped quasi-normal Markovian approximation give the value as $n_c\approx 3.45$. The energy spectrum for this range of exponents develops two length-scales, separating three distinct wavenumber ranges.Comment: 8 pages, no figure

House Flies: Manure, Media, and Microbes

This study was conducted to determine if there is a difference in bacterial abundance in house flies based on sex and rearing environment (manure versus artificial media) for house flies. This is important in determining the effectiveness of the facilities where the flies are being raised. Although, previous studies have shown differences in bacterial abundance between male and female house flies, it still remains unknown whether there is a discrepancy in bacterial abundance between rearing environments in the lab. We hypothesized that there would be a greater abundance of bacteria in females than males and a greater bacterial abundance in the manure environment than the artificial media. We determined that there was no significant difference between house fly sex or the environments in which they were raised. These results are meaningful because they introduce evidence of forced interaction that could skew the bacterial counts. In the future, the results would be more telling with a larger sample size.

Feedback methods for inverse simulation of dynamic models for engineering systems applications

Inverse simulation is a form of inverse modelling in which computer simulation methods are used to find the time histories of input variables that, for a given model, match a set of required output responses. Conventional inverse simulation methods for dynamic models are computationally intensive and can present difficulties for high-speed applications. This paper includes a review of established methods of inverse simulation,giving some emphasis to iterative techniques that were first developed for aeronautical applications. It goes on to discuss the application of a different approach which is based on feedback principles. This feedback method is suitable for a wide range of linear and nonlinear dynamic models and involves two distinct stages. The first stage involves design of a feedback loop around the given simulation model and, in the second stage, that closed-loop system is used for inversion of the model. Issues of robustness within closed-loop systems used in inverse simulation are not significant as there are no plant uncertainties or external disturbances. Thus the process is simpler than that required for the development of a control system of equivalent complexity. Engineering applications of this feedback approach to inverse simulation are described through case studies that put particular emphasis on nonlinear and multi-input multi-output models

Chronic pain assessments in children and adolescents : a systematic literature review of the selection, administration, interpretation, and reporting of unidimensional pain intensity scales

Background. Advances in pain assessment approaches now indicate which measures should be used to capture chronic pain experiences in children and adolescents. However, there is little guidance on how these tools should best be administered and reported, such as which time frames to use or how pain scores are categorised as mild, moderate, or severe. Objective. To synthesise current evidence on unidimensional, single-item pain intensity scale selection, administration, interpretation, and reporting. Methods. Databases were searched (inception: 18 January 2016) for studies in which unidimensional pain intensity assessments were used with children and adolescents with chronic pain. Ten quality criteria were developed by modifying existing recommendations to evaluate the quality of administration of pain scales most commonly used with children. Results. Forty-six studies met the inclusion criteria. The highest score achieved was 7 out of a possible 10 (median: 5; IQR: 4–6). Usage of scales varied markedly in administrator/completer, highest anchors, number of successive assessments, and time referent periods used. Conclusions. Findings suggest these scales are selected, administered, and interpreted inconsistently, even in studies of the same type. Furthermore, methods of administration are rarely reported or justified making it impossible to compare findings across studies. This article concludes by recommending criteria for the future reporting of paediatric chronic pain assessments in studies

Exercise rehabilitation for recovery from critical illness (Protocol)

Queen Margaret University, Edinburgh, UK. As part of an ongoing research education programme.This is the protocol for a review and there is no abstract. The objectives are as follows: The objective of this systematic review is to assess the effectiveness of exercise rehabilitation programmes, initiated after ICU discharge, on improving functional exercise capacity and quality of life in adult ICU survivors who have been mechanically ventilated for more than 24 hours. We will compare an exercise intervention to any other intervention or a control or 'usual care' programme. Exercise includes any structured or taught programmes. Respiratory or inspiratory muscle training is excluded due to it being initiated within the ICU environment, for example with weaning from a ventilator, and not as post-discharge rehabilitation as required for this review.sch_phyAngus 1997 Angus, DC. Understanding the incidence and long-term outcomes of ARDS. In: Gullo, A editor(s). 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[PUBMED: 3535411] Guyatt 2008 Guyatt GH, Oxman AD, Kunz R, Vist GE, Falck-Ytter Y, Schunemann HJ, et al.What is quality of evidence- and why is it important to clinicians?. BMJ 2008;336:995-8. [PUBMED: 18456631] Higgins 2008 Higgins JPT, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.1 [updated September 2008]. Available from www.cochrane-handbook.org: The Cochrane Collaboration, 2008. Iversen 2003 Iversen MD, Fossel AH, Katz JN. Enhancing function in older adults with chronic low back pain: a pilot study of endurance training. Archives of Physical Medicine and Rehabilitation 2003;84 (9):1324-31. [PUBMED: 13680569] Jolliffe 2001 Jolliffe J, Rees K, Taylor RRS, Thompson DR, Oldridge N, Ebrahim S. Exercise-based rehabilitation for coronary heart disease. Cochrane Database of Systematic Reviews 2001, Issue 1. [DOI: 10.1002/14651858.CD001800.] King 1998 King J, Crowe J. Mobilisation practices in Canadian critical care units. Physiotherapy Canada 1998;50(3):206-11. [MEDLINE: 0346574] Kouidi 2002 Kouidi E. Exercise training in dialysis patients: why, when, and how?. Artificial Organs 2002;26(12):1009-13. [PUBMED: 12460377] Krishnan 2002 Krishnan KR, Delong M, Kraemer H, Carney R, Spiegel D, Gordon C, et al.Comorbidity of depression with other medical diseases in the elderly. Biological Psychiatry 2002;52(6):559-88. [PUBMED: 12361669] Lavie 2009 Lavie CJ, Thomas RJ, Squires RW, Allison TG, Milani RV. Exercise training and cardiac rehabilitation in primary and secondary prevention of coronary heart disease. Mayo Clinic Proceedings 2009; 84(4):373-83. [PUBMED: 19339657] Lewis 2003 Lewis M. Intensive care unit rehabilitation within the United Kingdom: a review. Physiotherapy 2003;89(9):531-8. [DOI: 10.1016/S0031-9406(05)60179-4] Martin 2005 Martin M, Salim A, Murray J, Demetriades D, Belzberg H, Rhee P. The decreasing incidence and mortality of acute respiratory distress syndrome after injury: a 5-year observational study. Journal of Trauma 2005;50(5):1107-13. [PUBMED: 16385287] Mazzeo 2001 Mazzeo RS, Tanaka H. Exercise prescription for the elderly: current recommendations. Sports Medicine 2001;31(11):809-18. [PUBMED: 11583105] Miller 2002 Miller MD, Crotty M, Giles LC, Bannerman E, Whitehead C, Cobiac L, et al.Corrected arm muscle area: an independent predictor of long-term mortality in community dwelling older adults?. Journal of the America Geriatrics Society 2002;50(7): 1272-7. [PUBMED: 12133024] Paffenbarger 1986 Paffenbarger RS, Hyde RT, Wing AL, Hseih CC. Physical activity, all-cause mortality, and longevity of college alumni. New England Journal of Medicine 1986;314(10):605-13. [PUBMED: 3945246] Puhan 2006 Puhan MA, Busching G, Schunemann HJ, VanOort E, Zaugg C, Frey M. Interval versus continuous high-intensity exercise in chronic obstructive pulmonary disease: a randomized trial. Annals of Internal Medicine 2006;145(11):816-25. [PUBMED: 17146066] Rantanen 2000 Rantanen T, Harris T, Leveille SG, Visser M, Foley D, et al.Muscle strength and body mass index as long-term predictors of mortality in initially healthy men. Journal of Gerontology. Series A: Biological Sciences and Medical Sciences 2000;55(3):M168-73. [PUBMED: 10795731] RevMan 5.0 The Nordic Cochrane Centre, The Cochrane Collaboration. Review Manager (RevMan). 5.0. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2008. Schweickert 2009 Schweickert WD, Pohlman MC, Pohlman AS, Nigos C, Pawlik AJ, Esbrook CL, et al.Early physical and occupational therapy in mechanically ventilated, critically ill patients: a randomised controlled trial. Lancet 2009;373(epub):1874-82. [PUBMED: 19446324] Smith 2006 Smith TP, Kennedy SL, Smith M, Orent S, Fleshner M. Physiological improvements and health benefits during an exercisebased comprehensive rehabilitation program in medically complex patients. Exercise Immunology Review 2006;12:86-96. [PUBMED: 17201074] Stiller 2000 Stiller K. Physiotherapy in intensive care: toward an evidence-based practice. Chest 2000;118(6):1801-13. [PUBMED: 11115476] Storch 2008 Storch EK, Kruszynski DM. From rehabilitation to optimal function: role of clinical exercise therapy. Current Opinion in Critcal Care 2008;14(4):451-5. [PUBMED: 18614911] Wiles 2009 Wiles L, Stiller K. Passive limb movements for patients in an intensive care unit: A survey of physiotherapy practice in Australia. Journal of Critical Care 2009;epub:ahead of print. [PUBMED: 19819105] Yoshida 1999 Yoshida T, Kohzuki M, Yoshida K, Hiwatari M, Kamimoto M, Yamamoto C, et al.Physical and psychological improvements after phase II cardiac rehabilitation in patients with myocardial infarction. Nursing & Health Sciences 1999;1(3):163-70. [PUBMED: 10894639] Indicates the major publication for the study8pub1756pubArt.

A feasibility study for the detection of upper atmospheric winds using a ground based laser Doppler velocimeter

A possible measurement program designed to obtain the information requisite to determining the feasibility of airborne and/or satellite-borne LDV (Laser Doppler Velocimeter) systems is discussed. Measurements made from the ground are favored over an airborne measurement as far as for the purpose of determining feasibility is concerned. The expected signal strengths for scattering at various altitude and elevation angles are examined; it appears that both molecular absorption and ambient turbulence degrade the signal at low elevation angles and effectively constrain the ground based measurement of elevation angles exceeding a critical value. The nature of the wind shear and turbulence to be expected are treated from a linear hydrodynamic model - a mountain lee wave model. The spatial and temporal correlation distances establish requirements on the range resolution, the maximum detectable range and the allowable integration time

Laser Doppler velocimeter system simulation for sensing aircraft wake vortices. Part 2: Processing and analysis of LDV data (for runs 1023 and 2023)

A data analysis program constructed to assess LDV system performance, to validate the simulation model, and to test various vortex location algorithms is presented. Real or simulated Doppler spectra versus range and elevation is used and the spatial distributions of various spectral moments or other spectral characteristics are calculated and displayed. Each of the real or simulated scans can be processed by one of three different procedures: simple frequency or wavenumber filtering, matched filtering, and deconvolution filtering. The final output is displayed as contour plots in an x-y coordinate system, as well as in the form of vortex tracks deduced from the maxima of the processed data. A detailed analysis of run number 1023 and run number 2023 is presented to demonstrate the data analysis procedure. Vortex tracks and system range resolutions are compared with theoretical predictions

Laser Doppler velocimeter system simulation for sensing aircraft wake vortices

A hydrodynamic model of aircraft vortex wakes in an irregular wind shear field near the ground is developed and used as a basis for modeling the characteristics of a laser Doppler detection and vortex location system. The trailing vortex sheet and the wind shear are represented by discrete free vortices distributed over a two-dimensional grid. The time dependent hydrodynamic equations are solved by direct numerical integration in the Boussinesq approximation. The ground boundary is simulated by images, and fast Fourier Transform techniques are used to evaluate the vorticity stream function. The atmospheric turbulence was simulated by constructing specific realizations at time equal to zero, assuming that Kolmogoroff's law applies, and that the dissipation rate is constant throughout the flow field. The response of a simulated laser Doppler velocimeter is analyzed by simulating the signal return from the flow field as sensed by a simulation of the optical/electronic system