bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanodiamond dust and the energy distribution of quasars
Authors: Binette L. , Andersen A. C. , Mutschke H. , Haro‐Corzo S. 
Published: February 2006

AbstractThe spectral energy distribution of quasars shows a sharp steepening of the continuum shortward of ≃1100 Å. The steepening could be a result of dust absorption. We present a dust extinction model which considers crystalline carbon grains and compare it with SMC‐like dust extinction consisting of a mixture of silicate grains with graphite or amorphous carbon grains. We show that the sharp break seen in individual quasar spectra of intermediate redshift ∼1–2 can be reproduced by dust absorption provided the extinction curve consists of nanodiamonds, composed of terrestial cubic diamonds or of diamonds similar to the presolar nanodiamonds found in primitive meteorites. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AGN or starburst powered? Untangling the pan‐spectral SEDsof the high‐redshift radio galaxies and sub‐mm galaxies
Authors: Dopita M. A. , Reuland M. , Groves B. , Röttgering H. , van Breugel W. 
Published: February 2006

AbstractHere we show how theoretical pan‐spectral modelling is beginning to decode the physical parameters of the interstellar medium of starburst and high‐redshift galaxies, is revealing the star formation rate, identifying the bolometric contribution due to an embedded AGN and is determining the attenuation of the galaxian light due to foreground dust. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new technique for decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy
Authors: Sánchez S. F. , García‐Lorenzo B. , Jahnke K. , Mediavilla E. , González‐Serrano J. I. , Christensen L. , Wisotzki L. 
Published: February 2006

AbstractWe have developed a new technique to decouple the spectra of the host and the nucleus of type I AGNs using integral field spectroscopy (IFS) data. The technique is a simple extension of methods widely tested in 2D imaging. We present here the results from applying the technique to data taken with INTEGRAL at the 4.2 m WHT telescope on the Seyfert 1 radio‐galaxy 3C 120. We obtained, for the first time, a clean spectra of the host galaxy, without contamination from the nuclear source. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the evolution of the black‐hole/spheroid mass ratio
Authors: Mclure R. J. , Jarvis M. J. , Targett T. A. , Dunlop J. S. , Best P. N. 
Published: February 2006

AbstractWe present the results of a study which uses the 3CRR sample of radio‐loud active galactic nuclei (AGN) to investigate the evolution of the black‐hole:spheroid relation in the most massive early‐type galaxies from 0 < z < 2. Radioloud unification is exploited to obtain virial (line‐width) black‐hole mass estimates from the 3CRR quasars, and stellar mass estimates from the 3CRR radio galaxies, thereby providing black‐hole and stellar mass estimates for a single population of early‐type galaxies. At low redshift (z < 1) the 3CRR sample is consistent with a black‐hole:spheroid ratio ofM bh/M sph ≃ 0.002, in good agreement with that observed locally for quiescent galaxies of similar stellar mass (M sph ≃ 5 × 1011 M⊙). However, over the redshift interval 0 < z < 2 the 3CRR black‐hole:spheroid ratio is found to evolve as M bh/M sph ∝ (1 + z )2.07±0.76, reaching M bh/M sph ≃ 0.008 by redshift z ≃ 2. This evolution is found to be inconsistent with the local black‐hole:spheroid ratio remaining constant at a moderately significant level (98%). If confirmed, the detection of evolution in the 3CRR black‐hole:spheroid mass ratio further strengthens the evidence that, at least for massive early‐type galaxies, the growth of the central supermassive black hole may be completed before that of the host spheroid. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray and radio emission in the nuclei of radio galaxies and thedisk‐jet connection
Authors: Marscher A. P. 
Published: February 2006

AbstractIt appears that relativistic jets are produced by accreting black holes. We might therefore expect that events observed in jets, such as the appearance of bright radio knots moving at apparent superluminal speeds, originate as disturbances in the central engine. This is observed in a number of compact X‐ray binary systems in our Galaxy, manifested as changes in the X‐ray emission state followed by superluminal ejections. The author and collaborators have detected somewhat similar events in the radio galaxies 3C 120 (type Fanaroff‐Riley I) and 3C 111 (FR II). The data both confirm the disk‐jet connection in accreting supermassive black holes and provide constraints on the structure of the jet between the central engine and the millimeter‐wave core. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The jet in the radio galaxy 3C120: Jet/cloud interactions at parsec scales
Authors: Gómez J. L. , Marscher A. P. , Jorstad S. G. , Agudo I. 
Published: February 2006

AbstractThe radio galaxy 3C 120 appears as one of the best sources to study the emission and propagation of relativistic jets in active galactic nuclei. Muti‐wavelength multi‐epoch observations suggest that this Seyfert 1 galaxy is probably the result of a merger and presents a jet in precession that originates from the accretion of material onto a super massive central black hole. Thanks to its proximity and high activity it is possible to monitor the rapid changing rich inner jet structure with unprecedented spatial and temporal resolutions through very long baseline interferometry observations. The jet is pointing close to the line of sight, and is most probably interacting very dynamically with a cloud of properties intermediate of those of the broad and narrow emission‐line regions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Jets and their surroundings: Inevitable dissipation in high‐redshift jets
Authors: de Young D. 
Published: February 2006

AbstractAs jets pass through the ambient medium, dissipation of jet energy and momentum can occur due to interaction with this medium. This dissipation is mediated through the non‐linear development of global surface instabilities that create a turbulent mixing layer which resides initially on the surface of the jet. This layer expands in thickness with time, and in many cases it can permeate the entire jet volume, resulting in a fully mixed and turbulent jet. It is shown that the development of such dissipative mixing layers is inevitable for all classes of jet: subsonic, supersonic, relativistic, and MHD jets. The growth rates of the mixing layers are given, and it is shown that the development of this dissipative process increases rapidly with increasing redshift of the jets. Implications for highly collimated jets and the unsolved problem of jet content are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radio galaxies and type‐2 quasars in the Spitzer Extragalactic First Look Survey
Authors: Lacy M. , Sajina A. , Gates E. , the XFLS Team  
Published: February 2006

AbstractWe use mid‐infrared colour‐colour plots made with data from the Spitzer First Look Survey to explore the emission mechanisms of faint radio sources in that field. Using mid‐infrared colours alone, we are able to see the transition from a starburst‐dominated radio source population at sub‐mJy levels to the radiogalaxy/quasar population at mJy levels. Both FR I and some FR II galaxies show little or no mid‐infrared excess, suggesting they either lack dusty tori, or a strong continuum source to heat them, or both. Objects with hot, dusty tori, most likely radio‐intermediate and radio‐quiet AGN, make up a significant fraction of the faint radio source population. We also discuss the use of mid‐infrared colour‐colour plots to select radio quiet obscured AGN. Early results from imaging the host galaxies of these type‐2 quasars at high spatial resolution with adaptive optics indicates that they, like type‐1 quasars and radio galaxies, are often found to be hosted by giant elliptical galaxies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The VLA Low‐frequency Sky Survey
Authors: Cohen A. S. , Lane W. M. , Kassim N. E. , Lazio T. J. W. , Cotton W. D. , Perley R. A. , Condon J. J. , Erickson W. C. 
Published: February 2006

AbstractWe present an overview of the ongoing VLA Low‐frequency Sky Survey (VLSS, formerly known as 4MASS). The VLSS will map an area of 9.1 sr covering the entire sky above a declination of –30 degrees (or 75% of the full sky), at a frequency of 74 MHz (4 meter wavelength) with an unprecedented combination of sensitivity and resolution at this low frequency. The observational challenges at this wavelength include radio frequency interference (RFI), ionospheric phase distortions and a large field of view filled with sources. These challenges have been surmounted by a variety of new algorithms. The principle data products from the survey will be a set of publicly available images along with a source catalog of approximately 80 000 objects. Thus we will create an online virtual observatory at this previously unexplored frequency which will complement other major surveys at higher frequencies such as the NVSS. The most efficient way currently know to search for high redshift radio galaxies is to select ultra steep spectrum sources from low frequency surveys. The VLSS represents an excellent opportunity to pursue this method with its unique combination of large sky coverage and very low frequency, which may be especially useful for finding objects at z > 5. The observations are now roughly 50% complete, and we expect to complete most of the rest by late 2005. Current data products and more information are available on our website (URL http://lwa.nrl.navy.mil/VLSS). Basic research in radio astronomy at the Naval Research Laboratory is supported by the office of Naval Research. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Most supermassive black hole growth is obscured by dust
Authors: Martínez‐Sansigre A. , Rawlings S. , Lacy M. , Fadda D. , Marleau F. R. , Simpson C. , Willott C. J. , Jarvis M. J. 
Published: February 2006

AbstractWe present an alternative method to X‐ray surveys for hunting down the high‐redshift type‐2 quasar population, using Spitzer and VLA data on the Spitzer First Look Survey. By demanding objects to be bright at 24 µm but faint at 3.6 µm, and combining this with a radio criterion, we find 21 type‐2 radio‐quiet quasar candidates at the epoch at which the quasar activity peaked. Optical spectroscopy with the WHT confirmed 10 of these objects to be type‐2s with 1.4 ≤ z ≤ 4.2 while the rest are blank. There is no evidence for contamination in our sample, and we postulate that our 11 blank‐spectrum candidates are obscured by kpc‐scale dust as opposed to dust from a torus around the accretion disk. By carefully modelling our selection criteria, we conclude that, at high redshift, 50–80% of the supermassive black hole growth is obscured by dust. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Granada workshop on High Redshift Radio Galaxies: An overview
Authors: Röttgering H. J. A. 
Published: February 2006

AbstractThe Granada workshop on High Redshift Radio Galaxies (HzRGs) gave an excellent overview of the progress that has been made in this field during the last 3 years. Here we briefly review some of the results, with an emphasis on what studies of HzRGs can teach us about the formation and evolution of massive galaxies, clusters and active galactic nuclei (AGN). Of great relevance for this workshop are scenarios that describe certain aspects of the evolution of radio galaxies, including (i) the sequence of events after merging of galaxies that ultimately lead to extended powerful radio sources and (ii) the mass assembly and virialization of the hosting massive galaxies and their associated (proto‐)clusters. Furthermore, I briefly discuss two projects that are important for a further understanding of AGN and high redshift radio galaxies. First, using the MIDI instrument mounted on the VLT Interferometer, the dusty tori of nearby AGN can be studied in the range of 8–13 micron at high angular resolution. The first result on the nearby AGN NGC 1068 as presented by Jaffe et al. (2004) indicated the presence of a hot (T > 800 K), compact (≲1 pc) component, possible identified with the base of the jet and a warm (270 K), well‐resolved (3 × 4 pc) component associated with the alleged torus. Second, LOFAR is a new low frequency radio telescope that is currently being build in the Netherlands and is expected to be operational in 2008. With 50 stations spread over an area of 100 km in diameter, its resolution and sensitivity will be unprecedented in the frequency range 10–240 MHz. LOFAR will be a unique instrument that will impact a broad range of astrophysical topics varying from the epoch of reionisation, to gamma ray bursts and cosmic rays. Surveys with LOFAR will be of paramount importance for studies of HzRGs: It will enable (i) defining samples of radio galaxies with redshifts higher than 6, (ii) observations of starbursting galaxies in proto‐clusters, and (iii) mapping out the low‐frequency radio emission of virtually all northern radio‐loud AGN in revolutionary detail. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real‐time measurement of RFR energy distribution in the macaca mulatta head
Authors: Burr John G. , Krupp Jerome H. 
Published: February 2006

AbstractTemperature increases due to absorption of 1.2 GHz, CW, 70 mW/cm2, radio frequency (RF) energy, were measured in 3.3‐cm‐radius homogeneous muscle‐equivalent spheres, M. mulatta cadaver heads (both detached from and attached to the body) and living, anesthetized M. mulatta heads. Temperatures were measured with a Vitek, Model 101 Electrothermia Monitor and temperature distributions were compared to theoretical predictions from a thermal‐response model of a simulated cranial structure. The results show that the thermal response model accurately predicts the temperature distribution in muscle‐equivalent spheres, the distribution of temperature in detached M. mulatta heads when exposed from the back of the head, and the distribution of temperature in attached M. mulatta cadaver heads for animals oriented with body parallel to the H‐field. The temperature distribution in the detached M. mulatta heads varies markedly with exposure orientation, ie, facing forward, backward, or to the side. The orientation of the M. mulatta cadaver body significantly affects the temperature distribution in the head ‐ with H‐field orientation showing high, nonuniform values, and E‐field orientation showing low, uniform values. In live animals blood flow produces a significant short‐term effect on the temperature distribution in the midbrain, but not the cortex. Midbrain temperatures are both significantly higher and lower than the comparable cadaver measurements, depending on location.
Observing‐responses of rats exposed to 1.28‐ and 5.62‐GHz microwaves
Authors: de Lorge John O. , Ezell Clayton S. 
Published: February 2006

AbstractThe effects of microwave irradiation at two different frequencies (1.28 and 5.62 GHz) on observing‐behavior of rodents were investigated. During daily irradiation, eight male hooded rats performed on a two‐lever task; depression of one lever produced one of two different tones and the other lever produced food when depressed in the presence of the appropriate tone. At 5.62 GHz, the observing‐response rate was not consistently affected until the power density approximated 26 mW/cm2 at 1.28 GHz, the observing‐response rate of all rats was consistently affected at a power density of 15 mW/cm2. The respective whole‐body specific absorption rates (SARs) were 4.94 and 3.75 W/Kg. Measurements of localized SAR in a rat‐shaped model of simulated muscle tissue revealed marked differences in the absorption pattern between the two frequencies. The localized SAR in the model's head at 1.28 GHz was higher on the side distal to the source of radiation. At 5.62 GHz the localized SAR in the head was higher on the proximal side. It is concluded that the rat's observing behavior is disrupted at a lower power density at 1.28 than at 5.62 GHz because of deeper penetration of energy at the lower frequency, and because of frequency‐dependent differences in anatomic distribution of the absorbed microwave energy.
Effects of millimeter‐wave radiation on monolayer cell cultures. III. A search for frequency‐specific athermal biological effects on protein synthesis
Authors: Bush L. G. , Hill D. W. , Riazi A. , Stensaas L. J. , Partlow L. M. , Gandhi O. P. 
Published: February 2006

AbstractA method recently developed in this laboratory has been used to directly expose BHK‐21/C13 cells to high levels of microwave radiation without significant microwave‐induced heating (⩽ 0.1 °C). Monolayer cultures were grown on microwave‐transparent polystyrene coverslips, placed on the open end of a wave guide, and maintained at 37.2 °C during irradiation at frequencies in both the E‐ and U‐bands (average power densities 292 and 177 mW/cm2, respectively). Effects of microwave radiation were assessed at 0.1 GHz increments in the ranges of 38–48 GHz and 65–75 GHz. Protein synthesis was measured in quadruplicate cultures that were allowed to incorporate labeled methionine during the 15‐minute period of microwave irradiation. Autoradiographs of each monolayer culture were scanned along the region corresponding to the longer axis of the wave guide aperture using a microdensitometer to quantify incorporation. Since microwave power incident on the cells was previously shown to vary along this axis according to a cosine2 relationship from zero at each edge of the wave guide to twice the average power density at the center of the wave guide, this technique should reveal biological effects that might only be manifested in narrow amplitude domains or “power windows.” Observations of protein synthesis in monolayer cultures irradiated at 202 closely spaced frequencies in the E‐ and U‐bands failed to reveal changes associated with microwave exposure. Thus no evidence was obtained in support of the existence of frequency‐specific athermal biological effects of microwaves. In addition, no support was found for the existence of amplitude‐specific “power windows”.
In vitro study of microwave effects on calcium efflux in rat brain tissue
Authors: Shelton W. W. , Merritt J. H. 
Published: February 2006

AbstractIn this study we investigated the prospect of microwave‐induced alteration of 45Ca2+ efflux from rat neural tissue at low pulse repetition frequencies and low power densities under in vitro conditions. Rat cerebral tissue, preloaded with 45Ca2+, was exposed to pulsed‐microwave radiation (1‐GHz carrier frequency) according to one of several PRF‐power density exposure schemes: 16 Hz at 0.5, 1.0, 2.0, or 15 mW/cm2, or 32 Hz at 1.0 or 2.0 mW/cm2 average power density. Measurements of radioactivity in the efflux medium and in the tissue sample were used to calculate an efflux value for each sample. The results indicate that the radiation conditions used did not alter calcium efflux in rat brain tissue.
Prolonged microwave irradiation of rats: Effects on concurrent operant behavior
Authors: Lebovitz Robert M. 
Published: February 2006

AbstractTwo measures of performance were used to study the effects of pulse‐modulated microwave radiation (PM MWR) on schedule‐controlled operant behavior of rats: 1) cued (SD), fixed‐ratio (FR) bar pressing for food reinforcement; and 2) noncued (Sd) bar pressing in the absence of food reinforcement. The animals were irradiated and the behavioral data were obtained concurrently, during daily three‐hour sessions, five days per week for six to nine weeks. Each experiment began with a two to three‐week baseline interval of sham irradiation; a two to three‐week interval of sham irradiation followed the irradiation phase. The irradiated animals were exposed to 1.3‐Ghz PM MWR (pulse width of 1 microsecond at 600 pulses per second) at whole‐body, average specific absorbed‐dose rates of from 1.5–6.7 mW/g. Control and irradiated animals were tested in identical, cylindrical waveguide exposure/behavioral assemblies; different groups of irradiated and sham‐irradiated animals were used for each dose rate. At 1.5 mW/g, the levels of SD operant responding by control and irradiated animals were comparable, and showed similar progressive diminutions over the course of each daily session. Sd operant responding was more variable, but again comparable, with both groups showing similar, progressive declines in rate of responding during each session. At 3.6 mW/g, no specific effects on SD operant response rates were observed. However, there was an initial and transient increase in the rate of extinction of Sd responding. At 6.7 mW/g, SD response rates were slightly reduced, whereas there was a major reduction in noncued (Sd) operant responding followed by a sharp rebound during the first post‐MWR week. This marked reduction in Sd operant responding at MWR onset was in contrast to the relative stability and persistence of FR responding for food reinforcement.
Effect of nonionizing radiation on the purkinje cells of the rat cerebellum
Authors: Albert E. N. , Sherif M. F. , Papadopoulos N. J. , Slaby F. J. , Monahan J. 
Published: February 2006

AbstractIn one experiment, Sprague Dawley rats (16–21 days of gestation) and their offspring were exposed to 100‐MHz (CW) electromagnetic radiation at 46 mW/cm2 (SAR 2.77 mW/g) for 4 h/day for 97 days. In another experiment, the pregnant rats were irradiated daily from 17 to 21 days of gestation with 2450‐MHz (CW) microwaves at 10 mW/cm2 (SAR 2 mW/g) for 21 h/day. In a third experiment, 6‐day‐old rat pups were irradiated 7 h/day for five days with 2450‐MHz radiation at 10 mW/cm2. Equal numbers of animals were sham irradiated in each group. Quantitative studies of Purkinje cells showed a significant and irreversible decrease in rats irradiated during fetal or fetal and early postnatal life. In animals exposed postnatally, and euthanized immediately after irradiation, significant decrease in the relative number of Purkinje cells was apparent. However, restoration apparently occurred after forty days of recovery.
Biological effects of a 765‐kV transmission line: Exposures and thresholds in honeybee colonies
Authors: Greenberg Bernard , Bindokas Vytautas P. , Gauger James R. 
Published: February 2006

AbstractHoneybee colonies exposed under a 765‐kV, 60‐Hz transmission line at 7 kV/m show the following sequence of effects: 1) increased motor activity with transient increase in hive temperature; 2) abnormal propolization; 3) impaired hive weight gain; 4) queen loss and abnormal production of queen cells; 5) decreased sealed brood; and 6) poor winter survival. When colonies were exposed at 5 different E fields (7, 5.5, 4.1, 1.8, and 0.65–0.85 kV/m) at incremental distances from the line, different thresholds for biologic effects were obtained. Hive net weights showed significant dose‐related lags at the following exposures: 7 kV/m, one week; 5.5 kV/m, 2 weeks; and 4.1 kV/m, 11 weeks. The two lowest exposure groups had normal weight after 25 weeks. Abnormal propolization of hive entrances did not occur below 4.1 kV/m. Queen loss occurred in 6 of 7 colonies at 7 kV/m and 1 of 7 at 5.5 kV/m, but not below. Foraging rates were significantly lower only at 7 and 5.5 kV/m. Hive weight impairment and abnormal propolization occur at lower E‐field intensity than other effects and limit the “biological effects corridor” of the transmission line to approximately 23 m beyond a ground line projection of each outer phase wire. Intrahive E fields of 15–100 kV/m were measured with a displacement current sensor. Step‐potential‐induced currents up to 0.5 μA were measured in an electrically equivalent bee model placed on the honeycomb in a hive exposed at 7 kV/m. At 1.8 kV/m body currents were a few nanoamperes, or two orders of magnitude lower, and these colonies showed no effects. E‐field versus electric shock mechanisms are discussed.