Eddies, streams, and convergence zones in turbulent flows

Recent studies of turbulent shear flows have shown that many of their important kinematical and dynamical properties can be more clearly understood by describing the flows in terms of individual events or streamline patterns. These events or flow regions are studied because they are associated with relatively large contributions to certain average properties of the flow, for example kinetic energy, Reynolds stress, or to particular processes in the flow, such as mixing and chemical reactions, which may be concentrated at locations where streamlines converge for fast chemical reactions (referred to as convergence or C regions), or in recirculating eddying regions for slow chemical reactions. The aim of this project was to use the numerical simulations to develop suitable criteria for defining these eddying or vortical zones. The C and streaming (S) zones were defined in order to define the whole flow field. It is concluded that homogeneous and sheared turbulent flow fields are made up of characteristic flow zones: eddy, C, and S zones. A set of objective criteria were found which describe regions in which the streamlines circulate, converge or diverge, and form high streams of high velocity flow

"Community Development Banking, A Proposal to Establish a Nationwide System of Community Development Banks"

This brief proposes that the establishment of a nationwide system of community development banks (CDBs) would advance the capital development of the economy. The proposal is based on the notion that a critical function of the financial system is not being adequately performed by existing institutions for low-income citizens, inner-city minorities, and entrepreneurs who seek modest financing for small businesses. The primary goals of the CDBs are to deliver credit, payment, and savings opportunities to communities not well served by banks and to provide financing throughout a designated area for businesses too small to attract the interest of the investment banking and normal commercial banking communities.

The Mid-IR Spectral Effects of Darkening Agents and Porosity on the Silicate Surface Features of Airless Bodies

We systematically measured the mid-IR spectra of different mixtures of three silicates (antigorite, lizardite, and pure silica) with varying effective porosities and amounts of darkening agent (iron oxide and carbon). These spectra have broad implications for interpretation of current and future mission data for airless bodies, as well as for testing the capabilities of new instruments. Serpentines, such as antigorite and lizardite, are common to airless surfaces, and their mid-IR spectra in the presence of darkening agents and different surface porosities would be typical for those measured by spacecraft. Silica has only been measured in the plumes of Enceladus and presents exciting possibilities for other Saturn-system surfaces due to long range transport of E-ring material. Results show that the addition of the IR-transparent salt, KBr, to simulate surface porosity affected silicate spectra in ways that were not predictable from linear mixing models. The strengthening of silicate bands with increasing pore space, even when only trace amounts of KBr were added, indicates that spectral features of porous surfaces are more detectable in the mid-IR. Combining iron oxide with the pure silicates seemed to flatten most of the silicate features, but strengthened the reststrahlen band of the silica. Incorporating carbon with the silicates weakened all silicate features, but the silica bands were more resistant to being diminished, indicating silica may be more detectable in the mid-IR than the serpentines. We show how incorporating darkening agents and porosity provides a more complete explanation of the mid-IR spectral features previously reported on worlds such as Iapetus

The Meltdown of the Global Economy: A Keynes-Minsky Episode?

The enormity and pervasiveness of the global economic crisis that began in 2008 makes it relevant to analyze the circumstances that can explain this catastrophe. This will also provide clues to the appropriate remedial measures needed to prevent future occurrences of similar developments. The paper begins with some theoretical concerns relating to factors that could trigger a similar crisis. The first of these concerns relates to the deregulated financial institutions and the growing uncertainty that can be witnessed in these liberalized financial markets. The secondrelates to financial engineering with innovations in these markets, simultaneously providing cushions against risks while generating flows of liquidity that remain beyond the conventional sources of bank credit. Interpreting the role of uncertainty, one can observe the connections between investment and finance, both of which are subject to changes in the state of expectations. The initial formulation can be traced back to John Maynard Keynes's General Theory (1936), where liquidity preference is linked to asset prices and new investments. The Keynesian analysis of the impact of uncertainty related expectations was reformulated in 1986 by Hyman P. Minsky, who introduced the possibility of sourcing external finance through debt, which further adds to the impact of uncertainty. Minsky's characterization of deregulated financial markets considers the newfangled sources of nonbank credit, especially with the involvement of banks in the securities market under the universal banking model. As for the institutional arrangements that provide for profits on transactions, financial assets bought and sold in the primary market as initial public offerings of stocks are usually transacted later, in the secondary market, where these are no longer backed by physical assets.In the upswing, finance creates a myriad of financial claims and liabilities, and thus becomes increasingly remote from the real economy, while innovations to hedge and insulate assets continue to proliferate in the financial market, especially in the presence of uncertainty. The paper dwells on an account of the pattern of the financial crisis and its spread in the United States. This is appended by a stylized account of the turn of events in terms of a theoretical model that highlights the role of uncertainty in the process

Singular Effects of Spin-Flip Scattering on Gapped Dirac Fermions

We investigate the effects of spin-flip scattering on the Hall transport and spectral properties of gapped Dirac fermions. We find that in the weak scattering regime, the Berry curvature distribution is dramatically compressed in the electronic energy spectrum, becoming singular at band edges. As a result the Hall conductivity has a sudden jump (or drop) of $e^2/2h$ when the Fermi energy sweeps across the band edges, and otherwise is a constant quantized in units of $e^2/2h$. In parallel, spectral properties such as the density of states and spin polarization are also greatly enhanced at band edges. Possible experimental methods to detect these effects are discussed

Justifying the Special Theory of Relativity with Unconceived Methods

Many realists argue that present scientific theories will not follow the fate of past scientific theories because the former are more successful than the latter. Critics object that realists need to show that present theories have reached the level of success that warrants their truth. I reply that the special theory of relativity has been repeatedly reinforced by unconceived scientific methods, so it will be reinforced by infinitely many unconceived scientific methods. This argument for the special theory of relativity overcomes the critics’ objection, and has advantages over the no-miracle argument and the selective induction for it

The COVID-19 pandemic experiences of parents caring for children with oesophageal atresia/tracheo-oesophageal fistula

Purpose: The COVID-19 pandemic has resulted in a global health crisis of unparalleled magnitude. The direct risk to the health of children is low. However, disease-containment measures have society-wide impacts. This study explored the pandemic experiences of parents of children with oesophageal atresia/tracheo-oesophageal fistula (OA/TOF) in the UK. Design: A phenomenological approach underpinned use of an asynchronous online forum method, in collaboration with a patient support group. Data were evaluated using thematic analysis. Results: The online forum ran between 7 November and 18 December 2020 with 109 participants. Pandemic experiences were divided into themes relating to healthcare and disease containment. Participants described positive experiences with remote healthcare but identified limitations. Delays and cancellations led to escalation of care to an emergency level, slower developmental progress and feelings of being abandoned by services. Inpatient care was perceived as safe but caring alone was emotionally and practically challenging. Disease containment themes revealed anxiety regarding health risks, ‘collateral’ damage to well-being because of isolation, and an impact on finances and employment. Parents described a transition from worry about direct health risks to concern about the impact of isolation on socialisation and development. A process of risk–benefit analysis led some to transition to a more ‘normal life’, while others continued to isolate. Benefits to their child’s health from isolation were reported. Conclusions: Parents’ experiences of caring for a child with OA/TOF during the pandemic were varied. Rapid adoption of telehealth has demonstrated the enormous potential of remote healthcare delivery but requires refinement to meet the needs of the individual. Future pandemic planning should aim to retain community healthcare services to avoid escalation of care to an emergency, manage chronic and developmental concerns, and support parental well-being. Accurate and consistent disease-specific information is highly valued by parents. Third sector organisations are ideally positioned to support this. Data availability statement: No data are available. Although data have been anonymised, we have not made data available to protect the identity of those involved in the research, due to the detail provided by participants

The Social and Economic Importance of Full Employment

Unemployment was singled out by John Maynard Keynes as one of the principle faults of capitalism; the other is excessive inequality. Obviously, there is some link between these two faults: because: since most people living in capitalist economies must work for wages as a major source of their incomes, inability to obtain a job means lower income. If jobs can be provided to the unemployed, inequality and poverty will be reduced although such policy will not directly address the problem of excessive income at the top of the distribution. Most importantly, Keynes wanted to put unemployed labor to work not digging holes, but in socially productive ways. This would help to ensure that the additional effective demand created by government spending would not be exhausted in higher prices as it ran up against bottlenecks or other supply constraints. Further, it would help maintain public support for the government's programs by providing useful output. And it would generate respect for, and feelings of self-worth in, the workers employed in these projects (no worker would want to spend her days digging holes that serve no useful purpose). President Roosevelt's New Deal jobs programs (such as the Works Progress Administration and the Civilian Conservation Corps) are good examples of such targeted job-creating programs. These provided income and employment for workers, actually helped increase the nation's productivity, and left us with public buildings, dams, trails, and even music that we still enjoy today. As our nation (and the world) collapses into deep recession, or even depression, it is worthwhile to examine Hyman P. Minsky's comprehensive approach to resolving the unemployment problem