A Computational Channel Model for Magnetic Induction-Based Subsurface Applications

There are many underground applications based on magnetic fields generated by an oscillating magnetic source. For them, a magnetic dipole in a three-layered region with upper semi-infinite air layer can be a convenient idealization used for their planning, development, and operation. Solutions are in the form of the well-known Sommerfeld integral expressions that can be evaluated by numerical methods. A set of field expressions to be numerically evaluated by an efficient algorithm are not collected comprehensively yet, or at least in a directly usable form. In this paper, the explicit magnetic field solutions for the vertical magnetic dipole and the horizontal magnetic dipole for a general source-observer location are derived from the Hertz vector. They can be properly combined to model the problem of a tilted magnetic dipole source for horizontally or inclined stratified media. As a result, a complete set of integral equations of the Sommerfeld type valid from the near zone to the far zone are formulated. A method for numerical evaluation of the field expressions for high accurate computations is described. The numerical results are validated using the finite element method for all the possible source-receiver configurations and three well-spanned frequencies of typical subsurface applications. Both numerical solutions agree according to the normalized root-mean-square error-based fit metric. Numerical results for two cases of study are presented to see its usefulness for subsurface applications. A MATLAB implementation of the mathematical description outlined in this paper and the proposed evaluation method is freely available for download

Tenascin-C fragments are endogenous inducers of cartilage matrix degradation

Cartilage destruction is a hallmark of osteoarthritis (OA) and is characterized by increased protease activity resulting in the degradation of critical extracellular matrix (ECM) proteins essential for maintaining cartilage integrity. Tenascin-C (TN-C) is an ECM glycoprotein, and its expression is upregulated in OA cartilage. We aimed to investigate the presence of TN-C fragments in arthritic cartilage and establish whether they promote cartilage degradation. Expression of TN-C and its fragments was evaluated in cartilage from subjects undergoing joint replacement surgery for OA and RA compared with normal subjects by western blotting. The localization of TN-C in arthritic cartilage was also established by immunohistochemistry. Recombinant TN-C fragments were then tested to evaluate which regions of TN-C are responsible for cartilage-degrading activity in an ex vivo cartilage explant assay measuring glycosaminoglycan (GAG) release, aggrecanase and matrix metalloproteinase (MMP) activity. We found that specific TN-C fragments are highly upregulated in arthritic cartilage. Recombinant TN-C fragments containing the same regions as those identified from OA cartilage mediate cartilage degradation by the induction of aggrecanase activity. TN-C fragments mapping to the EGF-L and FN type III domains 3-8 of TN-C had the highest levels of aggrecan-degrading ability that was not observed either with full-length TN-C or with other domains of TN-C. TN-C fragments represent a novel mechanism for cartilage degradation in arthritis and may present new therapeutic targets for the inhibition of cartilage degradation

Changes in male rat urinary protein profile during puberty: a pilot study

BACKGROUND: Androgen-dependent proteins (lipocalins) circulate in blood of male rats and mice and, being small (~ 18 kDa), pass freely into glomerular filtrate. Some are salvaged in proximal nephrons but some escape in urine. Several organic molecules can bind to these proteins causing, where salvage occurs, nephropathy including malignancy in renal cortex. In urine, both free lipocalins and ligands contribute to an increasingly-recognised vital biological role in social communication between adults, especially in the dark where reliance is on smell and taste. Crystal structure of the first-characterised lipocalin of male rats, α2u-globulin, has been determined and peptide sequences for others are available, but no study of occurrence during early puberty has been made. We have followed temporal occurrence in urine of juveniles (n = 3) for non-invasive pilot study by high resolution gradient mini-gel electrophoresis, tryptic digest of excised protein bands, and LC-MS/MS of digest to identify peptide fragments and assign to specific lipocalins. Study objective refers directly to external availability for social communication but also indirectly to indicate kinetics of circulating lipocalins to which some xenobiotics may bind and constitute determinants of renal disease. RESULTS: Mini-gels revealed greater lipocalin complexity than hitherto recognised, possibly reflecting post-translational modifications. Earliest patterns comprised rat urinary protein 1, already evident in Sprague-Dawley and Wistar strains at 36 and 52 days, respectively. By 44 and 57 days major rat protein (α2u-globulin) occurred as the progressively more dominant protein, though as two forms with different electrophoretic mobility, characterised by seven peptide sequences. No significant change in urinary testosterone had occurred in Wistars when major rat protein became evident, but testosterone surged by 107 days concomitant with the marked abundance of excreted lipocalins. CONCLUSIONS: Qualitative temporal changes in the composition of excreted lipocalins early in puberty, and apparent increase in major urinary protein as two resolvable forms, should catalyse systematic non-invasive study of urinary lipocalin and testosterone dynamics from early age, to illuminate this aspect of laboratory rodent social physiology. It could also define the potential temporal onset of nephrotoxic ligand risk, applicable to young animals used as toxicological models

Dipole radio-frequency power from laser plasmas with no dipole moment

The radio-frequency power radiated from laser-target plasmas in a vacuum can be orders of magnitude greater than expected from such sources that have a negligible electric dipole moment. A model combining the Tidman-Stamper circuit model of a laser-target plasma with the theory of radiation from currents immersed in plasmas, however, predicts scaling of electric-dipole power radiated from laser plasmas in agreement with experiments.Comment: 3 pages, 2 figures, as published in Applied Physics Letter

Polarizing Grids, Their Assemblies and Beams of Radiation

This article gives an analysis of the behavior of polarizing grids and reflecting polarizers by solving Maxwell's equations, for arbitrary angles of incidence and grid rotation, for cases where the excitation is provided by an incident plane wave or a beam of radiation. The scattering and impedance matrix representations are derived and used to solve more complicated configurations of grid assemblies. The results are also compared with data obtained in the calibration of reflecting polarizers at the Owens Valley Radio Observatory (OVRO). From this analysis, we propose a method for choosing the optimum grid parameters (wire radius and spacing). We also provide a study of the effects of two types of errors (in wire separation and radius size) that can be introduced in the fabrication of a grid.Comment: 35 pages, 6 figure

An asymptotic form of the reciprocity theorem with applications in x-ray scattering

The emission of electromagnetic waves from a source within or near a non-trivial medium (with or without boundaries, crystalline or amorphous, with inhomogeneities, absorption and so on) is sometimes studied using the reciprocity principle. This is a variation of the method of Green's functions. If one is only interested in the asymptotic radiation fields the generality of these methods may actually be a shortcoming: obtaining expressions valid for the uninteresting near fields is not just a wasted effort but may be prohibitively difficult. In this work we obtain a modified form the reciprocity principle which gives the asymptotic radiation field directly. The method may be used to obtain the radiation from a prescribed source, and also to study scattering problems. To illustrate the power of the method we study a few pedagogical examples and then, as a more challenging application we tackle two related problems. We calculate the specular reflection of x rays by a rough surface and by a smoothly graded surface taking polarization effects into account. In conventional treatments of reflection x rays are treated as scalar waves, polarization effects are neglected. This is a good approximation at grazing incidence but becomes increasingly questionable for soft x rays and UV at higher incidence angles. PACs: 61.10.Dp, 61.10.Kw, 03.50.DeComment: 19 pages, 4 figure

Supported discharge service versus Inpatient care Evaluation (SITE): a randomised controlled trial comparing effectiveness of an intensive community care service versus inpatient treatment as usual for adolescents with severe psychiatric disorders: self-harm, functional impairment, and educational and clinical outcomes.

Background: Clinical guidelines recommend intensive community care service treatment (ICCS) to reduce adolescent psychiatric inpatient care. We have previously reported that the addition of ICCS led to a substantial decrease in hospital use and improved school re-integration. Aim: To undertake a randomised controlled trial (RCT) comparing an inpatient admission followed by an early discharge supported by ICCS with usual inpatient admission (treatment as usual; TAU). In this paper, we report the impact of ICCS on self-harm and other clinical and educational outcomes. Method: 106 patients aged 12-18 admitted for psychiatric inpatient care were randomised (1:1) to either ICCS or TAU. Six months after randomization, we compared the two treatment arms on the number and severity of self-harm episodes, the functional impairment, severity of psychiatric symptoms, clinical improvement, reading and mathematical ability, weight, height and the use of psychological therapy and medication. Results: At six-month follow-up, there were no differences between the two groups on most measures. Patients receiving ICCS were significantly less likely to report multiple episodes (5 or more) of self-harm (OR=0·18, 95% CI: 0·05 to 0·64). Patients admitted to private inpatient units spent on average 118.4 (95% CI: 28·2 to 208.6) fewer days in hospitals if they were in the ICCS group compared to TAU. Conclusion: The addition of ICCS to TAU may lower the risk of multiple self-harm and may reduce the duration of inpatient stay, especially in those patients admitted for private care. Early discharge with ICCS appears to be a viable alternative to standard inpatient treatment

Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau_mu = 2.197013(24) us, is in excellent agreement with the previous world average. The new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F = 1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.Comment: As published version (PRL, July 2007