Intrinsic echolocation capability of Hector's dolphin, Cephalorhynchus hectori.

A sonar system's echolocation capabilities can be inferred from the ambiguity distribution (defined here in terms of the conventional signal response function) of each of its transmitted signals. Several records of sounds emitted by Hector's dolphin are analyzed. The computed ambiguity distributions indicate that the sonar clicks of Hector's dolphins should be capable of resolving the ranges of targets as close together as 2 cm apart, but that target velocities cannot be resolved to any useful degree from a single echo.     

On a zero equation model of turbulence

In this paper we study a widely used zero equation model of turbulence. The governing equations are derived by applying to the incompressible Navier-Stokes equations the Reynolds time averaging procedure. We achieve closure by employing the eddy viscosity concept. Using the Implicit Function Theorem we obtain an existence and uniquencess result. We also discuss the existence of nonsingular solutions. Finally, we present an algorithm for solving the modeled equations.     

A Successful Implementation of Locating Passive Cooling Facilities: The Case of Northern Thailand

This paper reports the actual implementation of a location-allocation study, which is one aspect of the overall Passive Cooling (Thailand) Project conducted in Northern Thailand since 1985. The goal has been to generate decision supports for ‘optimal’ placements of cooling facilities and the assignment of sites to these facilities as part of the post-harvest handling-chain operation of agricultural products. The basic questions addressed in this work are the issues of how many facilities to set up and where to locate them for maximum utility. Our selected approach is to use discrete location-allocation modelling, as, among other reasons, the problem at hand has a most natural network setting. Direct methods as well as efficient heuristics are examined, and sample numerical results are reported as illustrations of the continual implementation.     

Determination of some hydroxycholesterols in human serum samples

The simultaneous determination of some hydroxycholesterols in human serum samples is described. The procedure is based on hydrolysis and extraction of these compounds in serum samples, followed by removal of especially cholesterol (making use of reversed-phase high-performance liquid chromatography) and derivatization of the purified compounds to their trimethylsilyl ethers and subsequent gas chromatography using flame ionization detection. Serum levels of 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol and 26-hydroxycholesterol were determined in several groups of patients: normals, untreated patients suffering from cerebrotendinous xanthomatosis, patients suffering from cerebrotendinous xanthomatosis and treated with either chenodeoxycholic acid or cholic acid in an effective dose, patients suffering from cerebro-hepato-renal syndrome, patients suffering from hypercholesterolemia and treated with cholestyramine for prolonged periods and one patient presumed to be suffering from an inborn error of metabolism in bile acid synthesis. It can be concluded that the 7 alpha-hydroxycholesterol concentration in serum is a good parameter for establishing disorders involving the metabolic conversion of 7 alpha-hydroxycholesterol towards bile acids. In addition, 26-hydroxycholesterol levels in patients suffering from cerebrotendinous xanthomatosis are beyond detectable limits, even during treatment with bile acids in an effective dose, whereas in all other conditions this compound is substantially present.     

Electrospraying: an in-situ polymerisation route for fabricating high macroporous scaffolds

This paper reports a direct jet-based polymerisation by polycondensation approach to forming a self-supporting scaffold structure. The processing technique is electrospraying, which is also known as electrohydrodynamic atomization. A specially formulated ethanolic siloxane sol derived from alkoxysilanes was synthesised and electrosprayed using a ring-shaped ground electrode configuration. The medium was seen to electrospray in the stable cone-jet mode, which later gave rise to the growing or forming of “fir-tree” like structures. The materials were characterised using microscopy, solid state NMR, FTIR, XRD and DSC. Hence this paper explains the direct controlled polycondensation from the siloxane sol and further presents the basis by which these scaffolds take shape.     

Cardy's formula for some dependent percolation models

We prove Cardy's formula for rectangular crossing probabilities in dependent site percolation models that arise from a deterministic cellular automaton with a random initial state. The cellular automaton corresponds to the zero-temperature case of Domany's stochastic Ising ferromagnet on the hexagonal lattice  (with alternating updates of two sublattices) [7]; it may also be realized on the triangular lattice 𝕋 with flips when a site disagrees with six, five and sometimes four of its six neighbors. Received: 24 December 2001     

New light on Hensel''s lemma

The historical development of Hensel's lemma is briefly discussed (Section 1). Using Newton polygons, a simple proof of a general Hensel's lemma for separable polynomials over Henselian fields is given (Section 3). For polynomials over algebraically closed, valued fields, best possible results on continuity of roots (Section 4) and continuity of factors (Section 6) are demonstrated. Using this and a general Krasner's lemma (Section 7), we give a short proof of a general Hensel's lemma and show that it is, in a certain sense, best possible (Section 8). All valuations here are non-Archimedean and of arbitrary rank. The article is practically self-contained.     

Computation of Autocorrelations of Interdeparture Times by Numerical Transform Inversion

The generating function of the autocorrelations of the interdeparture times in stationary M/G/1 and GI/M/1 systems involves the probability generating function of the number of customers served in a busy period. The latter function is implicitly determined as a solution to a functional equation. Standard methods for the numerical inversion of generating functions require the values of these functions at many complex arguments. A recently discovered substitution method for contour integrals allows the numerical inversion of implicitly determined generating functions without the numerical solution of the functional equations.     

An improved injector bunching geometry for ATLAS

The bunching system of the ATLAS positive ion injector (PII) has been improved by relocating the harmonic buncher to a point significantly closer to the second stage sine-wave buncher and the injector LINAC. The longitudinal optics design has also been modified and now employs a virtual waist from the harmonic buncher feeding the second stage sine-wave buncher. This geometry improves the handling of space charge for high-current beams, significantly increases the capture fraction into the primary rf bucket and reduces the capture fraction of the unwanted parasitic rf bucket. Total capture and transport through the PII has been demonstrated as high as 80% of the injected dc beam while the population of the parasitic, unwanted rf bucket is typically less than 3% of the total transported beam. To remove this small residual parasitic component a new traveling-wave transmission-line chopper has been developed reducing both transverse and longitudinal emittance growth from the chopping process. This work was supported by the U.S. Department of Energy under contract W-31-109-ENG-38.