Microwave radiometer for subsurface temperature measurement

A UHF radiometer, operating at a frequency of 800 MHz, was modified to provide an integral, three frequency voltage standing wave ratio (VSWR) circuit in the radio frequency (RF) head. The VSWR circuit provides readings of power transmission at the antenna-material interface with an accuracy of plus or minus 5 percent. The power transmission readings are numerically equal to the emissivity of the material under observation. Knowledge of material emissivity is useful in the interpretation of subsurface apparent temperatures obtained on phantom models of biological tissue. The emissivities of phantom models consisting of lean beefsteak were found to lie in the range 0.623 to 0.779, depending on moisture content. Radiometric measurements performed on instrumented phantoms showed that the radiometer was capable of sensing small temperature changes occurring at depths of at least 19 to 30 mm. This is consistent with previously generated data which showed that the radiometer could sense temperatures at a depth of 38 mm

Ocean foam generation and modeling

A laboratory investigation was conducted to determine the physical and microwave properties of ocean foam. Special foam generators were designed and fabricated, using porous glass sheets, known as glass frits, as the principal element. The glass frit was sealed into a water-tight vertical box, a few centimeters from the bottom. Compressed air, applied to the lower chamber, created ocean foam from sea water lying on the frit. Foam heights of 30 cm were readily achieved, with relatively low air pressures. Special photographic techniques and analytical procedures were employed to determine foam bubble size distributions. In addition, the percentage water content of ocean foam was determined with the aid of a particulate sampling procedure. A glass frit foam generator, with pore diameters in the range 70 - 100 micrometers, produced foam with bubble distributions very similar to those found on the surface of natural ocean foam patches

Searching for Massive Black Hole Binaries in the first Mock LISA Data Challenge

The Mock LISA Data Challenge is a worldwide effort to solve the LISA data analysis problem. We present here our results for the Massive Black Hole Binary (BBH) section of Round 1. Our results cover Challenge 1.2.1, where the coalescence of the binary is seen, and Challenge 1.2.2, where the coalescence occurs after the simulated observational period. The data stream is composed of Gaussian instrumental noise plus an unknown BBH waveform. Our search algorithm is based on a variant of the Markov Chain Monte Carlo method that uses Metropolis-Hastings sampling and thermostated frequency annealing. We present results from the training data sets and the blind data sets. We demonstrate that our algorithm is able to rapidly locate the sources, accurately recover the source parameters, and provide error estimates for the recovered parameters.Comment: 11 pages, 6 figures, Submitted to CQG proceedings of GWDAW 11, AEI, Germany, Dec 200

Reasons for female neonaticide in India

Invited commentary on ‘Neonaticide in India and the stigma of female gender: report of two cases’, Mishra et al

Use of the MultiNest algorithm for gravitational wave data analysis

We describe an application of the MultiNest algorithm to gravitational wave data analysis. MultiNest is a multimodal nested sampling algorithm designed to efficiently evaluate the Bayesian evidence and return posterior probability densities for likelihood surfaces containing multiple secondary modes. The algorithm employs a set of live points which are updated by partitioning the set into multiple overlapping ellipsoids and sampling uniformly from within them. This set of live points climbs up the likelihood surface through nested iso-likelihood contours and the evidence and posterior distributions can be recovered from the point set evolution. The algorithm is model-independent in the sense that the specific problem being tackled enters only through the likelihood computation, and does not change how the live point set is updated. In this paper, we consider the use of the algorithm for gravitational wave data analysis by searching a simulated LISA data set containing two non-spinning supermassive black hole binary signals. The algorithm is able to rapidly identify all the modes of the solution and recover the true parameters of the sources to high precision.Comment: 18 pages, 4 figures, submitted to Class. Quantum Grav; v2 includes various changes in light of referee's comment

Control in the technical societies: a brief history

By the time control engineering emerged as a coherent body of knowledge and practice (during and just after WW2) professional engineering societies had existed for many decades. Since control engineering is an interdisciplinary branch of the profession, new sections devoted to control were quickly established within the various existing technical societies. In addition, some new bodies devoted specifically or primarily to control were established. This article, a revised version of a paper presented at the IEEE 2009 Conference on the History of Technical Societies, describes how control engineering as a distinct branch of engineering became represented in technical societies in a number of countries

Modeling chemotaxis reveals the role of reversed phosphotransfer and a bi-functional kinase-phosphatase

Understanding how multiple signals are integrated in living cells to produce a balanced response is a major challenge in biology. Two-component signal transduction pathways, such as bacterial chemotaxis, comprise histidine protein kinases (HPKs) and response regulators (RRs). These are used to sense and respond to changes in the environment. Rhodobacter sphaeroides has a complex chemosensory network with two signaling clusters, each containing a HPK, CheA. Here we demonstrate, using a mathematical model, how the outputs of the two signaling clusters may be integrated. We use our mathematical model supported by experimental data to predict that: (1) the main RR controlling flagellar rotation, CheY6, aided by its specific phosphatase, the bifunctional kinase CheA3, acts as a phosphate sink for the other RRs; and (2) a phosphorelay pathway involving CheB2 connects the cytoplasmic cluster kinase CheA3 with the polar localised kinase CheA2, and allows CheA3-P to phosphorylate non-cognate chemotaxis RRs. These two mechanisms enable the bifunctional kinase/phosphatase activity of CheA3 to integrate and tune the sensory output of each signaling cluster to produce a balanced response. The signal integration mechanisms identified here may be widely used by other bacteria, since like R. sphaeroides, over 50% of chemotactic bacteria have multiple cheA homologues and need to integrate signals from different sources

The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems

In this work we examine the Cauchy convergence of both post-Newtonian (T-approximant) and re-summed post-Newtonian (P-approximant) templates for the case of a test-mass orbiting a Kerr black hole along a circular equatorial orbit. The Cauchy criterion demands that the inner product between the $n$ and $n+1$ order approximation approaches unity, as we increase the order of approximation. In previous works, it has been shown that we achieve greater fitting factors and better parameter estimation using the P-approximant templates for both Schwarzschild and Kerr black holes. In this work, we show that the P-approximant templates also display a faster Cauchy convergence making them a superior template to the standard post-Newtonian templates.Comment: 5 pages, Replaced with shortened published versio

Bolometric light curves of supernovae and post-explosion magnetic fields

The various effects leading to diversity in the bolometric light curves of supernovae are examined: nucleosynthesis, kinematic differences, ejected mass, degree of mixing, and configuration and intensity of the magnetic field are discussed. In Type Ia supernovae, a departure in the bolometric light curve from the full-trapping decline of $^{56}$Co can occur within the two and a half years after the explosion, depending on the evolutionary path followed by the WD during the accretion phase. If convection has developed in the WD core during the presupernova evolution, starting several thousand years before the explosion, a tangled magnetic field close to the equipartition value should have grown in the WD. Such an intense magnetic field would confine positrons where they originate from the $^{56}$Co decays, and preclude a strong departure from the full-trapping decline, as the supernova expands. This situation is expected to occur in C+O Chandrasekhar WDs as opposed to edge-lit detonated sub-Chandrasekhar WDs. If the pre-explosion magnetic field of the WD is less intense than 10$^{5-8}$G, a lack of confinement of the positrons emitted in the $^{56}$Co decay and a departure from full-trapping decline would occur. The time at which it takes place can provide estimates of the original magnetic field of the WD, its configuration, and also of the mass of the supernova ejecta. In SN 1991bg, the bolometric light curve suggests absence of a significant tangled magnetic field (intensity lower than $10^{3}$ G). Chandrasekhar-mass models do not reproduce the bolometric light curve of this supernova. For SN 1972E, on the contrary, there is evidence for a tangled configuration of the magnetic field and its light curve is well reproduced by a Chandrasekhar WD explosion.Comment: 54 pages, including 8 figures. To appear in Ap