bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environment and luminosity of supernova remnants
Authors: Hunt L. K. , Reynolds S. P. 
Published: May 2006

AbstractThe explosion of supernovae and the evolution of their remnants (SNRs) accelerate cosmic rays over a vast range of timescales. Magnetic fields can be investigated indirectly through one of the observational signatures of this acceleration, namely radio synchrotron emission. With the aim of better understanding the role of the magnetic field in supernova evolution, we explore the variation of SNR radio luminosities with physical conditions in the surrounding interstellar medium. With a data set that comprises more than 90 individual SNRs in 10 galaxies, and a range of 3000 in ISM density and 104 in radio synchrotron luminosity, we find a significant correlation between the two quantities. The observed trends support the hypothesis that adiabatic compression of magnetic fields by itself is insuf.cient to explain the radio emission of the brighter and more luminous in SNRs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamo and hydromagnetic liquid metal experiments
Authors: Colgate S. A. 
Published: May 2006

AbstractMagnetic dynamo experiments are being performed in many laboratories throughout the world. The most successful have been at Karlsruhe and Riga, where liquid sodium has been forced in constrained flows and has produced the predicted positive dynamo gain. The unconstrained flows are being investigated at Wisconsin, Cadarache, and Maryland. These experiments have not reached the critical values of the magnetic Reynolds number,Rm, necessary for dynamo gain, despite the positive predictions of laminar flow theory. Experiments in understanding the relationship of turbulence to MHD are being performed in addition to these at Perm, Princeton, and Swarthmore. A naturally constrained dynamo, using angular momentum gradient, Couette flow, to suppress turbulence is being attempted at New Mexico Tech. Flow constrained by ridged walls is likely to have less turbulence than unconstrained flow where the criterion of constraint is the degree of suppression of the Helmholtz shear flow instability. The study of MHD in conjunction with fluid turbulence has become of major importance in dynamo experiments as well as to future dynamo theory. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cosmic ray driven dynamo in galactic disks: effects of resistivity, SN rate and spiral arms
Authors: Hanasz M. , Otmianowska‐Mazur K. , Kowal G. , Lesch H. 
Published: May 2006

AbstractWe present a further development of the first numerical model of the magnetohydrodynamical dynamo, driven by cosmic rays in the interstellar medium (Hanasz et al. 2004). The cosmic rays are produced in randomly occurring supernova remnants. Our model is described by equations of magnetohydrodynamics supplemented with the diffusion‐advection equation governing the propagation of cosmic rays. The other essential elements of the model are: vertical gravity of the disk, differential rotation and resistivity leading to reconnection of magnetic field lines. We obtain amplification of the large‐scale magnetic field on a timescale of galactic rotation. The model represents a kind of fast, cosmic ray driven galactic dynamo proposed by Parker (1992). The amplification of the large‐scale magnetic field results from the buoyancy of the cosmic ray component in the interstellar medium. We describe five models characterized by different resistivity magnitudes, supply rates of cosmic rays and discuss in more detail a model with periodic SN activity, which mimics the presence of spiral arms in the disk. We find that both the resistivity and spiral arms enhance the efficiency of the cosmic–ray dynamo. The timescale of magnetic field amplification in this model is as short as 140 Myr. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A multi‐scale disk dynamo model
Authors: Stepanov R. , Frick P. , Sokoloff D. 
Published: May 2006

AbstractWe suggest to combine the mean‐field description of the galactic dynamo with a shell description of small‐scale turbulence for high values of hydrodynamic and magnetic Reynolds numbers. The model allows us to keep the balance of energy and realizes the kinematic and non‐linear regimes of the magnetic field generation. The suggested approach gives a possibility to study the role of magnetic helicity in the generation process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radio polarization and RM structure at high Galactic latitudes
Authors: de Bruyn A. G. , Katgert P. , Haverkorn M. , Schnitzeler D. H. F. M. 
Published: May 2006

AbstractWe present WSRT observations at low frequencies (315–388 MHz) of the diffuse polarized emission in an area of 6° × 6° at high Galactic latitude. Polarized emission is found to be ubiquitous with typical levels of about 3–5 K brightness temperature with a generally mottled structure. The Rotation Measure (RM) of the emission varies between values of –5 to +20 rad m–2. Most of the polarized emission appears Faraday thin with a single unresolved valued for the RM. The data suggest both inhomogeneous as well as dissimilar distribution functions of the synchrotron emitting and Faraday rotating media along the line of sight. The systematic patterns in the RM at this high Galactic latitude of +71° also provide evidence for significant variations in the vertical component of the local Galactic magnetic field at a level of 1 μ Gauss. The potential for Galactic polarimetry at even lower frequencies using LOFAR and SKA is briefly discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic fields in halos of spiral galaxies
Authors: Dettmar R.‐J. , Soida M. 
Published: May 2006

AbstractObservations of magnetic fields in halos of edge‐on disk galaxies are discussed in relation to the interstellar disk‐halo interface in disk galaxies. The distribution of extra‐planar diffuse ionized gas correlates on local and global scales with cosmic rays and magnetic fields as inferred from observations of the non‐thermal radio continuum radiation and its polarisation. From the polarisation a large‐scale and well‐ordered magnetic field in these gaseous halos can be deduced. For several objects a significant poloidal component of the halo field is likely. These observations indicate the presence of physical processes which generate and maintain magnetic fields on galactic scales. The importance of differential rotation of the gaseous halos for such processes is briefly discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong magnetic asymmetries in weakly interacting spirals
Authors: Chyży K. T. , Ehle M. , Beck R. 
Published: May 2006

AbstractWe investigate the influence of cluster environment on the structure and evolution of magnetic fields and the interstellar medium in the Virgo cluster spiral NGC 4254. Our sensitive interferometric (VLA) and single dish (Effelsberg) radio polarimetric observations reveal several magnetic spiral arms displaced from optical ones. However, the southern arm, particularly bright in polarized emission, lacks an optical counterpart. In this area the magnetic pitch angle is very small. On the contrary, the northern part of the galaxy with more diffuse total radio emission shows a significant radial component of the magnetic field. At 1.4 GHz the galaxy shows an extended polarized envelope with a highly regular magnetic field extending further than any star‐forming region. The regular component enters the cluster environment and can enrich the cluster‐scale magnetic field. Our XMM‐Newton observations reveal that the broadband X‐ray emission of the hot gas emerges from almost the whole galaxy disk and is tightly associated with regions of star formation. The distribution of Xrays does not show any sign of stripped hot gas around the galaxy disk and rules out strong ram pressure of the hot cluster gas. Magnetic asymmetries and slightly perturbed H I and optical emission probably manifest weak tidal interactions of NGC 4254 with other Virgo cluster members: the dark galaxy VIRGOHI 21 or NGC 4262. We also compare polarimetric properties of NGC 4254 with other Virgo cluster spirals which we currently observe systematically with the Effelsberg radio telescope. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radio sources and the evolution of the intracluster medium
Authors: De Young D. , Jones T. W. 
Published: May 2006

AbstractThe energy available from active galactic nuclei and their accompanying radio sources in clusters of galaxies have been suggested as energy sources that can solve the “cooling flow problem” in rich clusters of galaxies. In particular, fragmentation and subsequent mixing of buoyant radio source bubbles and relics has been proposed as a mechanism for mixing and reheating the intracluster medium. However, inclusion of the effects of the magnetic field present in the ICM of most clusters shows that the situation is more complex than might have been thought. Using self consistent 2‐D and 3‐D MHD calculations of the evolution of radio source bubbles in clusters, including their formation and including both galaxy and cluster gravitational potentials, it is shown that the buoyant bubbles are stable against fragmentation over times comparable to their buoyant risetimes and to the cooling times in clusters. In addition, lifting and mixing of the ICM is confined to volumes directly below the rising bubble and thus does not include an appreciable fraction of the overall volume of the ICM in the inner regions of clusters. Hence some additional mixing and fragmentation mechanisms may be required in order to effectively use radio sources in clusters as a means of general reheating of the ICM on times comparable in inner cluster cooling times. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarization and magnetic fields of giant radio galaxies
Authors: Jamrozy M. 
Published: May 2006

AbstractGiant double radio galaxies with a linear size greater than 1 Mpc (H 0 = 50 km s–1 Mpc–1) are the largest individual objects in the Universe. They are of particular interest in studying a number of astrophysical problems. One of them are magnetic fields associated with these sources, which play a crucial physical rôle in plasma processes over very large scales. In this paper, we report new VLA observations and show high‐frequency total‐power and polarization maps of the sources from the Machalski, Jamrozy & Zola (2001) sample. This sample and a comparison set of ‘normal‐size’ radio galaxies are used to study correlations between different physical properties of the lobes of FRII‐type sources. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear polarization in small radio sources
Authors: Rossetti A. , Mantovani F. , Dallacasa D. 
Published: May 2006

AbstractPolarimetric observations at 5 and 8.4 GHz have been performed for 3 CSS quasars. These observations are part of a programme aimed at studying the polarization characteristics of the core regions, jets, and lobes in such objects and at possibly finding of jet‐cloud interactions in CSSs. The behaviour of the fractional polarization and of the observed polarization angle as a function of λ 2 provides information on the density distribution of the ISM embedding the radio source, on its clumpiness and on the ordered and random components of the interstellar magnetic field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unbiased studies of diffuse extragalactic radio sources
Authors: Rudnick L. , Delain K. M. , Lemmerman J. A. 
Published: May 2006

AbstractWe present an overview of unbiased studies of diffuse extragalactic radio sources. We use a previously developed filtering technique to remove compact sources from large surveys such as WENSS, WISH, and NVSS and examine the residual diffuse emission. A search of these residuals, unbiased by optical or X‐ray selection, has uncovered a wide variety of diffuse sources, including those associated with groups of galaxies, “blank” fields, and previously unrecognized diffuse radio galaxy emission, as well as halos and relics of rich clusters. A second, targeted survey of the brightest X‐ray clusters results in a number of new sources, and illuminates some important selection effects. When the well‐established relationship between X‐ray and radio halo luminosities is extrapolated to lower levels, the apparent correlation holds quite well for any type of diffuse source, even background noise. The observed correlations must therefore be scrutinized for possible selection effects before physical interpretations are made. We briefly mention a wide‐field mapping project to search for large‐scale structures, and goals for the next generation of studies in magnetic field ‐ angular size parameter space. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mergers, relics and magnetic fields: The complex case of A2256
Authors: Clarke T. E. , Ensslin T. 
Published: May 2006

AbstractClusters of galaxies undergo multiple mergers during their lifetimes. Each merger drives shocks into the intracluster medium (ICM) which can heat the thermal gas, accelerate relativistic particles, and compress magnetic fields. Radio observations toward a number of clusters reveal large regions of diffuse synchrotron emission (halos and relics) which are not associated with individual host galaxies but are general properties of the ICM. Clusters host to this diffuse emission reveal significant evidence of recent or on‐going merger activity. We present deep VLA observations of the diffuse radio halo and relic emission in Abell 2256. Our new observations provide the first detailed image of the central diffuse radio halo emission in this cluster. The high fractional polarization of the relic allow us to use Faraday rotation measure observations to place constraints on the merger geometry of the system. In addition, the relic is composed of a number of synchrotron filaments which suggest the presence of spatially intermittent magnetic fields in this cluster. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evidence of gas heating by the central AGN in MKW 3s
Authors: Giacintucci S. , Mazzotta P. , Brunetti G. , Venturi T. , Bardelli S. 
Published: May 2006

AbstractWe present the results of radio observations of the galaxy cluster MKW 3s carried out at 1.28 GHz and 610 MHz with the Giant Metrewave Radio Telescope (GMRT). The Chandra observations of MKW 3s revealed that this cluster is characterized by a complex X‐ray structure hosting both a X‐ray .lament and a X‐ray cavity. The temperature structure of the cluster core is even more complex, with the presence of extended regions of gas heated above the radially averaged gas temperature at any radius. The magnetic field derived from the radio observations is ∼ 2 μG and provides radiative ages of the order of ∼ 2 × 108 yrs. Thanks to this estimate of the magnetic field strength and the comparison between the radio structure and the Chandra data, we found clear evidence for a close connection between the radio activity of the central AGN and the heated gas regions in this cluster. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic turbulence in cool cores of galaxy clusters
Authors: Vogt C. , Enßlin T. A. 
Published: May 2006

AbstractThe analysis of Faraday rotation measurements (RM) gives insight into the properties of cluster magnetic fields. Recently, Kolmogorov‐like magnetic turbulence was reported for the cool core of the Hydra A galaxy cluster which was derived using a maximum likelihood analysis of an RM map of this cluster (Vogt & Enßlin 2005). Here, we present our understanding of this power spectrum by kinetic energy injection through active galaxies which drive a turbulent non‐helical magnetic dynamo. We develop an analytical model of the turbulence in cool cores and show that it fits well to Faraday rotation measurements for a number of cool core clusters. Moreover, our model allows predictions for magnetic fields in clusters in which the appropriate observational information is still missing, and allows predictions for yet unobserved quantities like the hydrodynamical turbulence velocity and characteristic length scale, and suggests some level of magnetic intermittency and large‐scale hydrodynamic viscosity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fast growth of magnetic fields in galaxy clusters: a self‐accelerating dynamo
Authors: Schekochihin A. A. , Cowley S. C. 
Published: May 2006

AbstractWe propose a model of magnetic‐field growth in galaxy clusters whereby the field is ampli.fied by a factor of about 108 over a cosmologically short time of ∼ 108 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field‐amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small‐scale .uctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ∼ 10–15 G to trigger the explosive growth). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MHD simulations of plasma heating in clusters of galaxies
Authors: Asai N. , Fukuda N. , Matsumoto R. 
Published: May 2006

AbstractWe present the results of 2‐D magnetohydrodynamic (MHD) simulations of the plasma heating in clusters of galaxies. Both radiative cooling and anisotropic heat conduction are included. Magnetic turbulence is excited by the motion of gravitating clumps of the dark matter. These simulations enable us to study the thermal stability of a cluster core subjecting to turbulent magnetic fields.We found that moving clumps create hot regions ahead of them and that hot and cool plasmas coexist because magnetic fields suppress the heat conduction. Numerical results indicate that heat conduction from the hot region suspends the decrease of the temperature in the core for more than 1 Gyr. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical approaches to particle propagation and acceleration in turbulent intergalactic medium
Authors: Lazarian A. 
Published: May 2006

AbstractIntercluster medium is expected to be turbulent with turbulence being superAlfvenic at large scales. Magnetic fields substantially modify the turbulent cascade when the turbulence reaches the scales at which the fluctuation velocity gets less than the Alfven velocity. At those scales it is possible to consider three cascades, of fast, slow and Alfven modes with little energy exchange between them. As Alfvenic and slow modes are anisotropic they marginally scatter and accelerate cosmic rays, while fast modes dominate the processes. However, in the presence of cosmic rays the turbulence is modified as cosmic rays transfer the energy of compressible motions (i.e. slow and fast modes) from large scales to the scale of cosmic ray Larmor radius. This results in generation of a new small‐scale Alfvenic component which is not a part of the ordinary MHD cascade. This component does scatter and accelerate cosmic rays. In addition, magnetic reconnection in turbulent medium accelerates cosmic rays. The complexity of the intracluster turbulence calls for observational studies. A new technique Velocity Coordinate Spectrum (VCS) is particularly promising for studies of velocity fluctuations with a new generation of X‐ray observatories. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Future magnetic field studies using the Planck surveyor experiment
Authors: Enßlin T. A. , Waelkens A. , Vogt C. , Schekochihin A. A. 
Published: May 2006

AbstractThe Planck mission will permit measurements of the polarization of the cosmic microwave background and of polarized foregrounds such as our own Galaxy with an unprecedented combination of accuracy and completeness. This will provide information on cosmological and galactic magnetic fields. The latter can be studied in detail via nearly Faraday‐rotation free synchrotron and polarized dust emission. Methods are discussed to extract physically relevant information on the magnetic turbulence from Planck data and other measurements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Management of intrahepatic recurrence after curative treatment of colorectal liver metastases
Authors: Yan T D , Lian K Q , Chang D , Morris D L 
Published: May 2006

Abstract

Background
Management of intrahepatic recurrence after complete surgical treatment for colorectal liver metastases is not well defined. The aim of this study was to analyse the survival results of patients who had repeat liver resection for intrahepatic recurrence and to evaluate prognostic indicators for survival.

Methods
Between 1991 and 2005, 55 patients had repeat liver resection for isolated intrahepatic recurrence. The long-term survival results were assessed. Univariable and multivariable analyses were used to identify prognostic indicators for survival after repeat hepatectomy.

Results
The median survival was 53 (range 2–97) months and the 5-year survival rate was 49 per cent. In univariable analysis, size of largest initial liver metastasis, margin of initial liver surgery, carcinoembryonic antigen (CEA) level before and after initial liver surgery, liver disease-free survival, margin of repeat liver surgery, operation type of repeat surgery and CEA level before and after repeat surgery were significant prognostic factors. In multivariable analysis, largest initial liver metastasis 4 cm or less and CEA level 5 ng/ml or less after repeat liver surgery were independently associated with improved survival.

Conclusion
Repeat hepatectomy can achieve an acceptable survival in selected patients with isolated intrahepatic recurrence.
Psychopathy and malingering of psychiatric disorder in criminal defendants
Authors: Kucharski L. Thomas , Duncan Scott , Egan Shannon S. , Falkenbach Diana M. 
Published: May 2006

AbstractBecause the use of deception is an important clinical characteristic of psychopathy, there is intuitive appeal to the idea that psychopathy and malingering are associated. There is, however, very little research showing that psychopaths are more likely to malinger. We classified a sample of criminal defendants as high, moderate, or low in psychopathy, based on PCL‐R scores, and compared their scores on indices typically used to detect malingering on the MMPI‐2, the PAI and the SIRS. The high psychopathy group scored significantly higher on the MMPI‐2 F and F‐K; the PAI NIM, and the SIRS, but not the MMPI‐2 Fb, F(p), or the PAI RDF or Mal, lending some support for the DSM‐IV recommendation that malingering should be considered whenever there is a diagnosis of antisocial personality disorder. Logistic regression analysis (LGA) revealed that Factor I but not Factor II of the PCL‐R significantly discriminated malingerers from nonmalingerers with 75% correct classification. However, receiver operating characteristic (ROC) analysis revealed that psychopathy ratings had poor sensitivity and specificity in the detection of malingering. Calculation of the percentages of those exceeding accepted cut‐offs on each of the malingering measures revealed that a high percentage of severe psychopaths did not attempt to feign psychiatric disorder. The results suggest that psychopathy is not a clinically useful indictor of malingering. The results are discussed in terms of confirmatory bias and the impact such a bias could have on the evaluation of criminal defendants. Copyright © 2006 John Wiley & Sons, Ltd.