Hyperthermia heating apparatus

Electromagnetic energy is delivered to a localized area of a patient's body in a hyperthermic treatment so that it provides a uniform distribution of electromagnetic flux lines within the localized area of the patient's body and produces a uniform and localized heating gradient. An electrode array includes a number of electrodes which are arranged in pair, with the electrodes in each pair being spaced a particular distance apart. The array is driven by a balanced line system which is electromagnetically coupled to each pair of electrodes and which is shielded by a ground coaxial shield which itself is ground to the body of the patient. Each electrode is embedded in a Teflon stand-off in order to move the region of strong field, from the body, produced by rapidly changing potentials. The two pairs of electrodes forming a cross-like geometry are used with the balanced line systems. The electrical power is either multiplexed among the electrodes or the second pair is driven by a potential which is sinusoidal and which is 90% out of phase with the first balanced line system which is also sinusoidal

Application of imaging and ultrasound to the quality grading of beef

The results of a study conducted to assist the Department of Agriculture in the task of considering innovative methods for the grading of carcass beef for human consumption is presented. The processing of photographic, television and ultrasound images of the longissimus dorsi muscle at the 12/13th rib cut was undertaken. The results showed that a correlation could be developed between the quality grade of the carcass as determined by a professional grader, and the fat to area ratio of the muscle as determined by image processing techniques. In addition, the use of ultrasound shows the potential for grading of an unsliced carcass or a live animal

Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence

The TeV spectrum of H1426+428

The BL Lac object H1426+428 was recently detected as a high energy gamma-ray source by the VERITAS collaboration (Horan et al. 2002). We have reanalyzed the 2001 portion of the data used in the detection in order to examine the spectrum of H1426+428 above 250 GeV. We find that the time-averaged spectrum agrees with a power law of the shape dF/dE = 10^(-7.31 +- 0.15(stat) +- 0.16(syst)) x E^(-3.50 +- 0.35(stat) +- 0.05(syst)) m^(-2)s^(-1)TeV^(-1) The statistical evidence from our data for emission above 2.5 TeV is 2.6 sigma. With 95% c.l., the integral flux of H1426+428 above 2.5 TeV is larger than 3% of the corresponding flux from the Crab Nebula. The spectrum is consistent with the (non-contemporaneous) measurement by Aharonian et al. (2002) both in shape and in normalization. Below 800 GeV, the data clearly favours a spectrum steeper than that of any other TeV Blazar observed so far indicating a difference in the processes involved either at the source or in the intervening space.Comment: LaTeX, 8 pages, 4 figures, accepted for publication in Ap

Search for High Energy Gamma Rays from an X-ray Selected Blazar Sample

Our understanding of blazars has been greatly increased in recent years by extensive multi-wavelength observations, particularly in the radio, X-ray and gamma-ray regions. Over the past decade the Whipple 10m telescope has contributed to this with the detection of 5 BL Lacertae objects at very high gamma-ray energies. The combination of multi-wavelength data has shown that blazars follow a well-defined sequence in terms of their broadband spectral properties. Together with providing constraints on emission models, this information has yielded a means by which potential sources of TeV emission may be identified and predictions made as to their possible gamma-ray flux. We have used the Whipple telescope to search for TeV gamma-ray emission from eight objects selected from a list of such candidates. No evidence has been found for VHE emission from the objects in our sample, and upper limits have been derived for the mean gamma-ray flux above 390GeV. These flux upper limits are compared with the model predictions and the implications of our results for future observations are discussed.Comment: 15 pages, 2 figures, Accepted for publication in Ap

A Multi-wavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution

We report results from a multi-wavelength monitoring campaign on Mrk 421 over the period of 2003-2004. The source was observed simultaneously at TeV and X-ray energies, with supporting observations frequently carried out at optical and radio wavelengths. The large amount of simultaneous data has allowed us to examine the variability of Mrk 421 in detail. The variabilities are generally correlated between the X-ray and gamma-ray bands, although the correlation appears to be fairly loose. The light curves show the presence of flares with varying amplitudes on a wide range of timescales both at X-ray and TeV energies. Of particular interest is the presence of TeV flares that have no coincident counterparts at longer wavelengths, because the phenomenon seems difficult to understand in the context of the proposed emission models for TeV blazars. We have also found that the TeV flux reached its peak days before the X-ray flux during a giant flare in 2004. Such a difference in the development of the flare presents a further challenge to the emission models. Mrk 421 varied much less at optical and radio wavelengths. Surprisingly, the normalized variability amplitude in optical seems to be comparable to that in radio, perhaps suggesting the presence of different populations of emitting electrons in the jet. The spectral energy distribution (SED) of Mrk 421 is seen to vary with flux, with the two characteristic peaks moving toward higher energies at higher fluxes. We have failed to fit the measured SEDs with a one-zone SSC model; introducing additional zones greatly improves the fits. We have derived constraints on the physical properties of the X-ray/gamma-ray flaring regions from the observed variability (and SED) of the source. The implications of the results are discussed. (Abridged)Comment: 32 pages, 12 figures, to appear in Ap

A Search for TeV Gamma-Ray Emission from High-Peaked Flat Spectrum Radio Quasars Using the Whipple Air-Cherenkov Telescope

Blazars have traditionally been separated into two broad categories based upon their optical emission characteristics; BL Lacs, with faint or no emission lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission lines. The spectral energy distribution of FSRQs has generally been thought of as being more akin to the low-peaked BL Lacs, which exhibit a peak in the infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs), which exhibit a peak in UV/X-ray region of the spectrum. All blazars currently confirmed as sources of TeV emission are HBLs. Recent surveys have found several FSRQs exhibiting spectral properties similar to HBLs, particularly the synchrotron peak frequency. These objects are potential sources of TeV emission according to several models of blazar jet emission and blazar evolution. Measurements of TeV flux or upper limits could impact existing theories explaining the links between different blazar types and could have a significant impact on our understanding of the nature of objects that are capable of TeV emission. In particular, the presence (or absence) of TeV emission from FSRQs could confirm (or cast doubt upon) recent evolutionary models that expect intermediate objects in a transitionary state between FSRQ and BL Lac. The Whipple 10 meter imaging air-Cherenkov gamma-ray telescope is well suited for TeV gamma-ray observations. Using the Whipple telescope, we have taken data on a small selection of nearby(z<0.1 in most cases), high-peaked FSRQs. Although one of the objects, B2 0321+33, showed marginal evidence of flaring, no significant emission was detected. The implications of this paucity of emission and the derived upper limits are discussed.Comment: accepted for publication in Astrophysical Journa

Spectrum of very high energy gamma-rays from the blazar 1ES 1959+650 during flaring activity in 2002

The blazar 1ES 1959+650 was observed in a flaring state with the Whipple 10 m Imaging Atmospheric Cerenkov Telescope in 2002 May. A spectral analysis has been carried out on the data from that time period, and the resulting very high energy gamma-ray spectrum (E greater than or equal to 316 GeV) can be well fitted by a power law of differential spectral index alpha = 2.78 +/- 0.12(stat) +/- 0.21(sys). On 2002 June 4, the source flared dramatically in the gamma-ray range without any coincident increase in the X-ray emission, providing the first unambiguous example of an orphan\u27\u27 gamma-ray flare from a blazar. The gamma-ray spectrum for these data can also be described by a simple power-law fit with alpha = 2.82 +/- 0.15(stat) +/- 0.30(sys). There is no compelling evidence for spectral variability or for any cutoff to the spectrum

TeV Gamma-Ray Observations of the Galactic Center

We report a possible detection of TeV gamma-rays from the Galactic Center by the Whipple 10m gamma-ray telescope. Twenty-six hours of data were taken over an extended period from 1995 through 2003 resulting in a total significance of 3.7 standard deviations. The measured excess corresponds to an integral flux of \Flux above an energy of $2.8 \mathrm{TeV}$, roughly 40% of the flux from the Crab Nebula at this energy. The 95% confidence region has an angular extent of about 15 arcmin and includes the position of Sgr A*. The detection is consistent with a point source and shows no evidence for variability