2,787 research outputs found
High frequency-heated air turbojet
A description is given of a method to heat air coming from a turbojet compressor to a temperature necessary to produce required expansion without requiring fuel. This is done by high frequency heating, which heats the walls corresponding to the combustion chamber in existing jets, by mounting high frequency coils in them. The current transformer and high frequency generator to be used are discussed
Prohibition Harms the Weakest: Does Consumer Irrationality Justify the War on Drugs?
When—if ever—is state control of individual decisions better than self-control?
In the rational consumer model, the answer is never. That paradigm assumes that consumers
know their own preferences, possess all relevant information, process that information correctly,
and make consistent decisions over time. Government interference with individual choices—the
substitution of state control for self-control—can therefore only harm individuals, who would
make optimal decisions on their own.
The rational model has a long history. Many economists still view that model as one useful
approach to positive and normative questions. Other economists and non-economists, however,
believe many consumers are not fully rational. Their alternative assessment arises both from
casual observation of human behavior and from experimental research in behavioral economics
and psychology that appears to challenge the rational consumer model.1
If consumers are not fully rational, the case for self-control rather than state control might seem
less compelling. Government interference would not automatically reduce the well-being of nonrational consumers, since those non-rational consumers might be making sub-optimal decisions
on their own behalf.
I argue, however, that consumer irrationality strengthens, rather than weakens, the case for
self-control. I make that argument in the context of the “War on Drugs”—the US government’s
century-long attempt to eliminate marijuana, cocaine, heroin, and other intoxicating or mindaltering substances. If consumers are rational about drug use, prohibition makes them worse off.
If consumers are not necessarily rational, prohibition might prevent some “bad” decisions to use
drugs unnecessarily, so prohibition may seem worth considering.
As I will explain, however, the War on Drugs is still bad policy — indeed, it’s an even worse policy
if some consumers are non-rational. Prohibition might deter some ill-advised drug use, but its
overall consequences harm irrational consumers more than rational consumers. Self-control as
the approach to drugs might not be perfect, but state control is almost certainly worse
Optimized bone grafting.
Bone grafting is routinely performed in periodontology and oral surgery to fill bone voids. While autogenous bone is considered the gold standard because of its regenerative properties, allografts and xenografts have more commonly been utilized owing to their availability as well as their differential regenerative/biomechanical properties. In particular, xenografts are sintered at high temperatures, which allows for their slower degradation and resorption rates and/or nonresorbable features. As a result, clinicians have combined xenografts with other classes of bone grafts (most notably allografts and autografts in various ratios) for procedures requiring better long-term stability, such as contour grafting, sinus elevation procedures, and vertical bone augmentations. This review addresses the regenerative properties of each class of bone grafts and then highlights the importance of understanding each of their biomechanical and regenerative properties for clinical applications, including extraction site management, contour augmentation, sinus grafting, and horizontal and vertical augmentation procedures. Thereafter, an introduction toward the novel production of nonresorbable bone allografts (NRBAs) via high-temperature sintering is presented. These NRBAs not only pose the advantage of being more biocompatible than xenografts owing to their origin (human vs. animal bone) but also display nonresorbable properties similar to those of xenografts. Thus, while packaging allografts with xenografts in premixtures specific to various clinical indications has never been permitted owing to cross-species contamination and FDA/CE requirements, the discovery and production of NRBAs allows premixing with standard allografts in various ratios without regulatory restrictions. Therefore, premixtures of allografts with NRBAs can be produced in various ratios for specific indications (e.g., a 1:1 ratio similar to an allograft/xenograft mixture for sinus grafting) without the need for purchasing separate classes of bone grafts. This optimized form of bone grafting could theoretically provide clinicians more precise ratios without the need to purchase separate bone grafts. This review highlights the future potential for simplified and optimized bone grafting in periodontology and implant dentistry
Lagrangian dynamical geography of the Gulf of Mexico
We construct a Markov-chain representation of the surface-ocean Lagrangian
dynamics in a region occupied by the Gulf of Mexico (GoM) and adjacent portions
of the Caribbean Sea and North Atlantic using satellite-tracked drifter
trajectory data, the largest collection so far considered. From the analysis of
the eigenvectors of the transition matrix associated with the chain, we
identify almost-invariant attracting sets and their basins of attraction. With
this information we decompose the GoM's geography into weakly dynamically
interacting provinces, which constrain the connectivity between distant
locations within the GoM. Offshore oil exploration, oil spill contingency
planning, and fish larval connectivity assessment are among the many activities
that can benefit from the dynamical information carried in the geography
constructed here.Comment: Submitted to Scientific Report
Polymerization on the Diamond Hierarchical Lattice: The Migdal-Kadanoff Renormalization-Group Scheme
The thermodynamics of the equilibrium polymerization model (grand-canonical ensemble of self-avoiding walks) in two dimensions is worked out by means of the Migdal-Kadanoff renormalization-group technique. This method involves renormalization-group flows in an eight-dimensional parameter space. At the critical point the number of relevant fields (positive exponents) is four. The leading exponent value differs by less than 1% from the (presumed) exact value. The results are exact for the polymerization problem defined on the diamond hierarchical lattice. Some results are peculiar to this lattice and are not expected to hold for Bravais lattices. For instance, the polymerized phase (infinite polymerization index) is dilute (zero density of chemical bonds)
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