Evolution of isolated turbulent trailing vortices

In this work, the temporal evolution of a low swirl-number turbulent Batchelor vortex is studied using pseudospectral direct numerical simulations. The solution of the governing equations in the vorticity-velocity form allows for accurate application of boundary conditions. The physics of the evolution is investigated with an emphasis on the mechanisms that influence the transport of axial and angular momentum. Excitation of normal mode instabilities gives rise to coherent large scale helical structures inside the vortical core. The radial growth of these helical structures and the action of axial shear and differential rotation results in the creation of a polarized vortex layer. This vortex layer evolves into a series of hairpin-shaped structures that subsequently breakdown into elongated fine scale vortices. Ultimately, the radially outward propagation of these structures results in the relaxation of the flow towards a stable high-swirl configuration. Two conserved quantities, based on the deviation from the laminar solution, are derived and these prove to be useful in characterizing the polarized vortex layer and enhancing the understanding of the transport process. The generation and evolution of the Reynolds stresses is also addressed

Phase decorrelation, streamwise vortices and acoustic radiation in mixing layers

Several direct numerical simulations were performed and analyzed to study various aspects of the early development of mixing layers. Included are the phase jitter of the large-scale eddies, which was studied using a 2-D spatially-evolving mixing layer simulation; the response of a time developing mixing layer to various spanwise disturbances; and the sound radiation from a 2-D compressible time developing mixing layer

Food for All

This book is a historical review of international food and agriculture since the founding of the international organizations following the Second World War, including the World Bank and the Food and Agriculture Organization of the United Nations (FAO), the World Food Programme (WFP) and into the 1970s, when CGIAR was established and the International Fund for Agricultural Development (IFAD) was created to recycle petrodollars. The book concurrently focuses on the structural transformation of developing countries in Asia and Africa, with some making great strides in small farmer development and in achieving structural transformation of their economies. Some have also achieved Sustainable Development Goals (SDGs), particularly SDG2, but most have not. Not only are some countries, particularly in South Asia and sub-Saharan Africa, lagging behind, but they face new challenges of climate change, competition from emerging countries, population pressure, urbanization, environmental decay, dietary transition, and now pandemics. Lagging developing countries need huge investments in human capital, and physical and institutional infrastructure, to take advantage of rapid change in technologies, but the role of international assistance in financial transfers has diminished. The COVID-19 pandemic has not only set many poorer countries back but starkly revealed the weaknesses of past strategies. Transformative changes are needed in developing countries with international cooperation to achieve better outcomes. Will the change in US leadership bring new opportunities for multilateral cooperation

Food for All

This book is a historical review of international food and agriculture since the founding of the international organizations following the Second World War, including the World Bank and the Food and Agriculture Organization of the United Nations (FAO), the World Food Programme (WFP) and into the 1970s, when CGIAR was established and the International Fund for Agricultural Development (IFAD) was created to recycle petrodollars. The book concurrently focuses on the structural transformation of developing countries in Asia and Africa, with some making great strides in small farmer development and in achieving structural transformation of their economies. Some have also achieved Sustainable Development Goals (SDGs), particularly SDG2, but most have not. Not only are some countries, particularly in South Asia and sub-Saharan Africa, lagging behind, but they face new challenges of climate change, competition from emerging countries, population pressure, urbanization, environmental decay, dietary transition, and now pandemics. Lagging developing countries need huge investments in human capital, and physical and institutional infrastructure, to take advantage of rapid change in technologies, but the role of international assistance in financial transfers has diminished. The COVID-19 pandemic has not only set many poorer countries back but starkly revealed the weaknesses of past strategies. Transformative changes are needed in developing countries with international cooperation to achieve better outcomes. Will the change in US leadership bring new opportunities for multilateral cooperation

Comparison of haemodynamic parameters in two different geriatric age groups undergoing cemented bipolar hemiarthroplasty

Background: To conduct a prospective observational study to compare the haemodynamic changes in two age groups, group A: 60-75yrs and group B: >75yrs during cemented bipolar hemiarthroplasty for hip fractures under spinal anaesthesia.Methods: Patients of either sex belonging to above two groups, with no contra-indications for central neuraxial block received spinal anesthesia at lumbar level. Heart Rate (HR), Systolic Blood Pressure(SBP), Diastolic Blood Pressure(DBP) and Mean Arterial Pressure(MAP), pulse pressure variability(PPV), arterial oxygen saturation (SpO2), Electrocardiogram for any changes and nasal  end tidal CO2 (EtCO2) were recorded at the following time points:  baseline(on table), after giving spinal, after giving surgical position, at the start of surgery, at femoral canal reaming, immediately after cement insertion, every 2 minutes after cement insertion, femoral joint reduction and the end of the surgery. Hypotension, bradycardia, arrythmias, desaturation or unexpected loss of consciousness occurring in peri-cementation period suggestive of ‘Bone cement implantation syndrome’(BCIS) or any other adverse event was recognized and treated.Results: The SBP, HR, PPV, ETCO2, SPO2 and incidence of adverse events; were comparable in both the groups. The difference in the DBP and MAP was statistically significant.Conclusions: The difference in the occurrence of haemodynamic alterations was more in the older age group. Continuous vigilant monitoring during bipolar hemiarthroplasty is required