Water-filled heat pipe useful at moderate temperatures

Heat pipe is used in the primary heat exchanger for nuclear power plants, as a heat sink for high-power electronic devices, and in a closed-cycle heat rejection mechanism for cryogenic storage tanks. It serves simultaneously as a heat transfer device and as a structural member

Parametric inference in the large data limit using maximally informative models

Motivated by data-rich experiments in transcriptional regulation and sensory neuroscience, we consider the following general problem in statistical inference. When exposed to a high-dimensional signal S, a system of interest computes a representation R of that signal which is then observed through a noisy measurement M. From a large number of signals and measurements, we wish to infer the "filter" that maps S to R. However, the standard method for solving such problems, likelihood-based inference, requires perfect a priori knowledge of the "noise function" mapping R to M. In practice such noise functions are usually known only approximately, if at all, and using an incorrect noise function will typically bias the inferred filter. Here we show that, in the large data limit, this need for a pre-characterized noise function can be circumvented by searching for filters that instead maximize the mutual information I[M;R] between observed measurements and predicted representations. Moreover, if the correct filter lies within the space of filters being explored, maximizing mutual information becomes equivalent to simultaneously maximizing every dependence measure that satisfies the Data Processing Inequality. It is important to note that maximizing mutual information will typically leave a small number of directions in parameter space unconstrained. We term these directions "diffeomorphic modes" and present an equation that allows these modes to be derived systematically. The presence of diffeomorphic modes reflects a fundamental and nontrivial substructure within parameter space, one that is obscured by standard likelihood-based inference.Comment: To appear in Neural Computatio

Equitability, mutual information, and the maximal information coefficient

Reshef et al. recently proposed a new statistical measure, the "maximal information coefficient" (MIC), for quantifying arbitrary dependencies between pairs of stochastic quantities. MIC is based on mutual information, a fundamental quantity in information theory that is widely understood to serve this need. MIC, however, is not an estimate of mutual information. Indeed, it was claimed that MIC possesses a desirable mathematical property called "equitability" that mutual information lacks. This was not proven; instead it was argued solely through the analysis of simulated data. Here we show that this claim, in fact, is incorrect. First we offer mathematical proof that no (non-trivial) dependence measure satisfies the definition of equitability proposed by Reshef et al.. We then propose a self-consistent and more general definition of equitability that follows naturally from the Data Processing Inequality. Mutual information satisfies this new definition of equitability while MIC does not. Finally, we show that the simulation evidence offered by Reshef et al. was artifactual. We conclude that estimating mutual information is not only practical for many real-world applications, but also provides a natural solution to the problem of quantifying associations in large data sets

Foreign and domestic bank participation in emerging markets: lessons from Mexico and Argentina

It is generally agreed that strong domestic financial systems play an important role in attaining overall economic development and stabilization. The role played by foreign banks in achieving this goal, however, is still controversial. This article brings new evidence to the debate over foreign participation by examining the lending patterns of domestic and foreign banks in Argentina and Mexico during the 1990s. The authors conclude that foreign banks in both countries typically have stronger and less volatile loan growth than their domestic counterparts. The corollary to this finding, however, is that bank health—not ownership per se—is the critical element in the growth, volatility, and cyclicality of bank credit. Still, diversity of ownership is found to contribute to greater credit stability in times of financial system turmoil and weakness.Bank loans - Argentina ; Bank loans - Mexico ; Banks and banking, Foreign ; Argentina ; Mexico

Foreign and Domestic Bank Participation in Emerging Markets: Lessons from Mexico and Argentina

The Asian Crisis has highlighted the importance of strong domestic financial systems in overall economic development and stabilization. Less agreement is evident on the role of foreign banks in achieving this goal. We explore this issue by studying bank-specific data on lending by domestically- and foreign-owned banks in Argentina and Mexico. We find that foreign banks generally have had higher loan growth rates than their domestically-owned counterparts, with lower volatility of lending, contributing to lower overall volatility of credit. Additionally, in both countries, foreign banks show notable credit growth during crisis periods. In Argentina, the loan portfolios of foreign and domestic privately-owned banks are similar, and lending rates analogously respond to aggregate demand fluctuations. In Mexico, foreign and domestic banks with lower levels of impaired assets have similar loan responsiveness and portfolios. State-owned banks (Argentina) and banks with high levels of impaired assets (Mexico) have more stagnant loan growth and weak responsiveness to market signals. Overall, these findings suggest that bank health, and not ownership per se, is the critical element in the growth, volatility, and cyclicality of bank credit. Diversity in ownership appears to contribute to greater stability of credit in times of crisis and domestic financial system weakness.

Flow visualization experiments in a porous nozzle

An experimental approach is described for the study of nozzle flows with large wall-transpiration rates. Emphasizing a qualitative understanding of the flow, the technique uses the hydraulic analogy, whereby a compressible gas flow is simulated by a water flow having a free surface. For simplicity, the simulated gas flow is taken to be two-dimensional. A nozzle with porous walls in the throat region has been developed for use on a water table. A technique for visualizing the transpired fluid has also been devised. These are discussed, and preliminary results are presented which illustrate the success of the experimental approach

Rapid and deterministic estimation of probability densities using scale-free field theories

The question of how best to estimate a continuous probability density from finite data is an intriguing open problem at the interface of statistics and physics. Previous work has argued that this problem can be addressed in a natural way using methods from statistical field theory. Here I describe new results that allow this field-theoretic approach to be rapidly and deterministically computed in low dimensions, making it practical for use in day-to-day data analysis. Importantly, this approach does not impose a privileged length scale for smoothness of the inferred probability density, but rather learns a natural length scale from the data due to the tradeoff between goodness-of-fit and an Occam factor. Open source software implementing this method in one and two dimensions is provided.Comment: 4 pages, 4 figures. Major revision in v3. The "Density Estimation using Field Theory" (DEFT) software package is available at https://github.com/jbkinney/13_def

Alien Registration- Kinney, Freda B. (Mars Hill, Aroostook County)

https://digitalmaine.com/alien_docs/33900/thumbnail.jp

Numerical study of large-eddy breakup and its effect on the drag characteristics of boundary layers

The break-up of a field of eddies by a flat-plate obstacle embedded in a boundary layer is studied using numerical solutions to the two-dimensional Navier-Stokes equations. The flow is taken to be incompressible and unsteady. The flow field is initiated from rest. A train of eddies of predetermined size and strength are swept into the computational domain upstream of the plate. The undisturbed velocity profile is given by the Blasius solution. The disturbance vorticity generated at the plate and wall, plus that introduced with the eddies, mix with the background vorticity and is transported throughout the entire flow. All quantities are scaled by the plate length, the unidsturbed free-stream velocity, and the fluid kinematic viscosity. The Reynolds number is 1000, the Blasius boundary layer thickness is 2.0, and the plate is positioned a distance of 1.0 above the wall. The computational domain is four units high and sixteen units long