Broadband Measurement of Complex Permittivity Using Reflection Method and Coaxial Probes

This paper describes and evaluates a method for determining complex permittivity, and presents results of permittivity measurement of some substances. Complex permittivity of a phantom of biological muscle tissue, of some industrial chemicals and dielectrics is found. A non-destructive and non-invasive method based on reflection coefficient measurement of an open-ended coaxial line attaching the material under test is used. Two coaxial probes are under investigation. Vector measurement of the reflection coefficient on the interface between probes and measured samples is performed with the aid of network analyzer in the frequency range from 300 kHz to 3 GHz. Numerical modeling (FDTD) is compared with measurement. The results indicate that using the coaxial probe with dimensions of N connector the method is suitable in the frequency range approximately from 30 MHz to 1 GHz and using the probe with dimensions of SMA connector in range approximately from 30 MHz to 3 GHz

Comparison of Constant and Temperature Dependent Blood Perfusion in Temperature Prediction for Superficial Hyperthermia

The purpose of this study was to determine whether prediction of the 3D temperature profile for superficial hyperthermia using constant blood perfusion model could be matched to one with a temperature dependent blood perfusion. We compared three different constant blood perfusion scenarios with one temperature dependent blood perfusion using a layered model of biological tissue consisting of skin (2 mm), fat (10 mm) and muscle (108 mm). For all four scenarios the maximum temperature of 43 °C was found in the muscle tissue in the close proximity (1 – 3 mm) of fat layer. Cumulative histograms of temperature versus volume were identical for the region of 100x100x40 mm3 under the applicator aperture for the three constant blood perfusion models. For temperature dependent blood perfusion model, 85 % of the studied region was covered with the temperature equal or higher than 40 °C in comparison with 43 % for the constant blood perfusion models. Hence this study demonstrates that constant blood perfusion scenarios cannot be matched to one with a temperature dependent blood perfusion

Contamination of short GRBs by giant magnetar flares: significance of downwards revision in distance to SGR 1806-20

We highlight how the downward revision in the distance to the star cluster associated with SGR1806-20 by Bibby et al. reconciles the apparent low contamination of BATSE short GRBs by intense flares from extragalactic magnetars without recourse to modifying the frequency of one such flare per 30 years per Milky Way galaxy. We also discuss the variety in progenitor initial masses of magnetars based upon cluster ages, ranging from ~50 Msun for SGR 1806-20 and 1E 1647-455 in Westerlund 1 to ~15 Msun for SGR 1900+14 and presumably 1E 1841-045 if it originated from one of the massive RSG clusters #2 or #3

New BVI_C Photometry of Low-mass Pleiades Stars: Exploring the Effects of Rotation on Broadband Colors

We present new BVI_C photometry for 350 Pleiades proper motion members with 9 < V ≾ 17. Importantly, our new catalog includes a large number of K- and early M-type stars, roughly doubling the number of low-mass stars with well-calibrated Johnson/Cousins photometry in this benchmark cluster. We combine our new photometry with existing photometry from the literature to define a purely empirical isochrone at Pleiades age (≈100 Myr) extending from V = 9 to 17. We use the empirical isochrone to identify 48 new probable binaries and 14 likely nonmembers. The photometrically identified single stars are compared against their expected positions in the color-magnitude diagram (CMD). At 100 Myr, the mid K and early M stars are predicted to lie above the zero-age main sequence (ZAMS) having not yet reached the ZAMS. We find in the B – V versus V CMD that mid K and early M dwarfs are instead displaced below (or blueward of) the ZAMS. Using the stars' previously reported rotation periods, we find a highly statistically significant correlation between rotation period and CMD displacement, in the sense that the more rapidly rotating stars have the largest displacements in the B – V CMD

The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs

We report parallax measurements for 70 ultracool dwarfs (UCDs). Using both literature values and our sample, we report new polynomial relations between spectral type and M$_{JHK}$. Including resolved L/T transition binaries in the relations, we find no reason to differentiate between a "bright" (unresolved binary) and "faint" (single source) sample across the L/T boundary. Isolating early T dwarfs, we find that the brightening of T0-T4 sources is prominent in M$_{J}$ where there is a [1.2 - 1.4] magnitude difference. A similar yet dampened brightening of [0.3 - 0.5] magnitude happens at M$_{H}$ and a plateau or dimming of [-0.2 - -0.3] magnitude is seen in M$_{K}$. Comparing with evolutionary models that vary gravity, metallicity, and cloud thickness we find that a near constant temperature of 1200 $\pm$100 K along a narrow spectral subtype of T0-T4 is required to account for the brightening and color magnitude diagram of the L-dwarf/T-dwarf transition. Furthermore, there is a significant population of both L and T dwarfs which are red or potentially "ultra-cloudy" compared to the models, many of which are known to be young indicating a correlation between enhanced photospheric dust and youth. For the low surface-gravity or young companion L dwarfs we find that 8 out of 10 are at least [0.2-1.0] magnitude underluminous in M$_{JH}$ and/or M$_{K}$ compared to equivalent spectral type objects. We speculate that this is a consequence of increased dust opacity and conclude that low-surface gravity L dwarfs require a completely new spectral-type/absolute magnitude polynomial for analysis.Comment: 65 pages, Accepted for publication to Ap

Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf

We report the detection of periodic (p = 1.96 hours) bursts of extremely bright, 100% circularly polarized, coherent radio emission from the M9 dwarf TVLM 513-46546. Simultaneous photometric monitoring observations have established this periodicity to be the rotation period of the dwarf. These bursts, which were not present in previous observations of this target, confirm that ultracool dwarfs can generate persistent levels of broadband, coherent radio emission, associated with the presence of kG magnetic fields in a large-scale, stable configuration. Compact sources located at the magnetic polar regions produce highly beamed emission generated by the electron cyclotron maser instability, the same mechanism known to generate planetary coherent radio emission in our solar system. The narrow beams of radiation pass our line of sight as the dwarf rotates, producing the associated periodic bursts. The resulting radio light curves are analogous to the periodic light curves associated with pulsar radio emission highlighting TVLM 513-46546 as the prototype of a new class of transient radio source.Comment: 12 pages, 3 figures, accepted for publication in ApJ Letter

Observational constraints on the afterglow of GRB 020531

We present the data acquired by the TAROT automated observatory on the afterglow of GRB 020531. Up to now, no convincing afterglow emission has been reported for this short/hard GRB at any wavelength, including X-ray and optical. The combination of our early limits, with other published data allows us to put severe constraints on the afterglow magnitude and light curve. The limiting magnitude is 18.5 in R band, 88 minutes after the GRB, and the decay slope power law index could be larger than 2.2.Comment: 4 pages, submitted to A&A (letter

Loop-mediated isothermal amplification (LAMP) assays for the species-specific detection of Eimeria that infect chickens

<p>Abstract</p> <p>Background</p> <p><it>Eimeria </it>parasites can cause the disease coccidiosis in poultry and even subclinical infection can incur economic loss. Diagnosis of infection predominantly relies on traditional techniques including lesion scoring and faecal microscopy despite the availability of sensitive molecular assays, largely due to cost and the requirement for specialist equipment. Despite longstanding proven efficacy these traditional techniques demand time and expertise, can be highly subjective and may under-diagnose subclinical disease. Recognition of the tight economic margins prevailing in modern poultry production and the impact of avian coccidiosis on poverty in many parts of the world has highlighted a requirement for a panel of straightforward and sensitive, but cost-effective, <it>Eimeria </it>species-specific diagnostic assays.</p> <p>Results</p> <p>Loop-mediated isothermal amplification (LAMP) is an uncomplicated, quick and relatively inexpensive diagnostic tool. In this study we have developed a panel of species-specific LAMP assays targeting the seven <it>Eimeria </it>species that infect the chicken. Each assay has been shown to be genuinely species-specific with the capacity to detect between one and ten eimerian genomes, equivalent to less than a single mature schizont. Development of a simple protocol for template DNA preparation from tissue collected post mortem with no requirement for specialist laboratory equipment supports the use of these assays in routine diagnosis of eimerian infection. Preliminary field testing supports this hypothesis.</p> <p>Conclusions</p> <p>Development of a panel of sensitive species-specific LAMP assays introduces a valuable new cost-effective tool for use in poultry husbandry.</p