Measurements of Pulsating Turbulent Water Flow in a Tube

The experimental method associated with obtaining meaningful information from the hot-film anemometer signals in fully developed pulsating turbulent flow where the pulsations are sinusoidal in time is discussed. The results of a number of experiments in water reveal the nature of the longtime and short-time average velocity and pressure. Velocity measurements between 0.95 radii and the centerline demonstrate that the long-time average velocity distribution is coincident with that for steady turbulent flow at the same Reynolds number. Also, no significant differences between the longtime average axial pressure drop in the pulsating and steady flows were noted, although this requires further investigation in view of the increases in the Reynolds stress observed in pulsating air flow. The distribution of the measured pulsating velocity component depends upon the dimensionless turbulent frequency. At the lowest values of the frequency, the profile is turbulent-like, while at higher values, the maximum in the velocity shifts from the centerline towards the wall and a uniform speed region exists over the central portion of the tube. An eddy viscosity model displays many of the important characteristics of the observed pulsating velocity. Using the results of this model and the experimental observations, limits of the laminar frequency parameter which delineates the response of the flow are suggested. Recordings of the instantaneous velocity signal suggest the short-time behavior of the axial turbulence intensity to be generally that of increasing during deceleration of the flow and decreasing during acceleration

Active drug targeting

Over 100 years ago, Paul Ehrlich first proposed the side-chain theory to explain how living cells mount an immune response in reaction to an infection. His theory stated that upon the encounter of a threat, cells express side-chains to bind dangerous toxins. These side-chains, which he later named receptors, can break off the cell and circulate throughout the body (i.e. antibodies). Specific antibodies link to particular antigens in the same way that Emil Fischer proposed enzymes bind to their receptors, “as lock and key”. Ehrlich described these so-called “keys” or antibodies as “magic bullets”, which target toxins without harming the body. In recent years, research has focused on using antibodies not only for detection of infection, but also as aids for drug targeting. Thereby, antibodies are bound to the surface of carriers (e.g. nanoparticles) and facilitate a directed transport to a specific organ or site in the body. Aptamer- peptide- or folic acid-doped carriers furthermore have been shown to specifically target cancer cells. By using hydrophilic structures as carriers (e.g. polyethylene glycol), negative side effects resulting from the accumulation of innate proteins can be prevented. Currently, there are drug carriers in the pre-clinical development phase for the treatment of bowel cancer. Thereby, nano polymer capsules coated with a specific antibody are used to target a glycoprotein expressed on bowel cancer cells. The polymers have a size of approximately 500 nm and are produced with a so-called “layer-by-layer” procedure. Once the carrier has reached its target site, the drug needs to be released in a controlled manner. This can be facilitated, for example, by applying a magnetic field in the case of iron oxide particles. Once these particles are taken up by the cells, magnetic radiation can be used to excite the particles, resulting in the rupture of the cell and subsequent cell death

Asteroid exploration and utilization

The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources possessed by asteroids have enormous potential for aiding and enhancing human space exploration as well as life on Earth. Project STONER (Systematic Transfer of Near Earth Resources) is based on mining an asteroid and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plan for humans to utilize asteroid resources. Project STONER is divided into two parts: asteroid selection and explorer spacecraft design. The spacecraft design team is responsible for the selection and integration of the subsystems: GNC, communications, automation, propulsion, power, structures, thermal systems, scientific instruments, and mechanisms used on the surface to retrieve and store asteroid regolith. The sample return mission scenario consists of eight primary phases that are critical to the mission

Global Assessment Report on Disaster Risk Reduction 2019

The Global Assessment Report on Disaster Risk Reduction (GAR) is the flagship report of the United Nations on worldwide efforts to reduce disaster risk

Populism and Central Bank Independence

The consensus that surrounded the granting of central bank independence in the pursuit of a price stability oriented monetary policy has been challenged in the aftermath of the global financial crisis, in the light of the rise of populism on the one hand and the expanded mandates of central banks on the other hand. After considering the economic case for independence and the three Ds (distributional, directional and duration effects), the paper examines three different dimensions in the debate of how the rise in populism - or simply general discontent with the status quo - affects central bank independence. Finally, the paper examines how to interpret the legality of central bank mandates, and whether or not central banks have exceeded their powers. This analysis leads us in turn to consider accountability and, in particular, the judicial review of central bank actions and decisions. It is important to have in place adequate mechanisms to "guard the guardians" of monetary and financial stability

Capital Inflows to Latin America: The 1970s and 1990s

For the first time since the onset of the debt crisis in the slimmer or 1982, capital began to return to Latin America during 1990 and 1991.In general, Latin America's re-entry into the international capital markets was perceived as a positive development. However, policy-makers in the region have also voiced concern about the less favourable side-effects of these capital inflows. First, it was feared that the real exchange rate appreciation that of tell accompanies these inflows would adversely affect the international competitiveness of the export sector. Second, there was concern thatthe inflows could be reversed abruptly, possibly doing considerable damage to the domestic financial system in the process. The fear (If reversal was based on the experience of the debt crisis, which followed on the heels of the 'capital bonanza' of 1978-81. This chapter compares the recent capital inflows experience with that of the late 1970s. The analysis examines the differences and similarities between the two episodes over three broad areas:1. Domestic macroeconomic conditions in the recipient countries at the outset of both episodes. 2. The behaviour of the external factors that influence the international allocation of capital.3. The response of key macroeconomic variables, such as the real exchange rate, reserves, and stock prices to the inflow of capital