bluuebunny/crossref_metadata_2025_split huggingface dataset:
The surface magnetic fields of T Tauri stars
Authors: Hussain Gaitee A. J. , Cameron Andrew Collier , Jardine Moira , Donati Jean-Francois 
Published: April 2009

AbstractWe present surface magnetic field maps of the two accreting T Tauri stars, CV Cha and CR Cha. Our magnetic field maps show evidence for strong, complex multi-polar fields similar to those obtained on young rapidly rotating main sequence stars. Both CV Cha and CR Cha show magnetic field patterns that are more complex than those recovered for the lower mass, fully convective T Tauri star, BP Tau.By comparing our maps with previously published maps of classical T Tauri stars, we infer that magnetic field patterns on T Tauris, and their underlying magnetic field generation mechanisms evolve quickly as they develop radiative cores. This may have implications for the efficiency with which T Tauri stars can effectively lock onto their surrounding disks under the magnetospheric accretion model scenario. This, in turn, has implications for the angular momentum evolution of T Tauri stars as they evolve towards the main sequence.
The magnetic field structure in NGC 253 in presence of a galactic wind
Authors: Heesen Volker , Krause M. , Beck R. , Dettmar R.-J. 
Published: April 2009

AbstractWe present radio continuum polarimetry observations of the nearby edge-on galaxy NGC 253 which possesses a very bright radio halo. Using the vertical synchrotron emission profiles and the lifetimes of cosmic-ray electrons, we determined the cosmic-ray bulk speed as 300±30 km s−1, indicating the presence of a galactic wind in this galaxy. The large-scale magnetic field was decomposed into a toroidal axisymmetric component in the disk and a poloidal component in the halo. The poloidal component shows a prominent X-shaped magnetic field structure centered on the nucleus, similar to the magnetic field observed in other edge-on galaxies. Faraday rotation measures indicate that the poloidal field has an odd parity (antisymmetric). NGC 253 offers the possibility to compare the magnetic field structure with models of galactic dynamos and/or galactic wind flows.
Magnetic fields and cosmic rays in galaxy clusters and large scale structures
Authors: Dolag Klaus , Stasyszyn F. , Donnert J. , Pakmor R. 
Published: April 2009

AbstractIn galaxy clusters, non-thermal components such as magnetic field and high energy particles keep a record of the processes acting since early times till now. These components play key roles by controlling transport processes inside the cluster atmosphere and beyond and therefore have to be understood in detail by means of numerical simulations. The complexity of the intra cluster medium revealed by multi-frequency observations demonstrates that a variety of physical processes are in action and must be included properly to produce accurate and realistic models. Confronting the predictions of numerical simulations with observations allows us to validate different scenarios about origin and evolution of large scale magnetic fields and to investigate their role in transport and acceleration processes of cosmic rays.
Magnetism in the nearby galaxy M 33
Authors: Tabatabaei F. S. , Krause M. , Beck R. , Fletcher A. 
Published: April 2009

AbstractUsing high-resolution data of the linearly polarized intensity and polarization angle at 3.6, 6.2, and 20 cm together with a 3-D model of the regular magnetic field, we study variations of the structure, strength, and energy density of the magnetic field in the Scd galaxy M 33. The regular magnetic field consists of a horizontal component (represented by an axisymmetric mode from 1 to 3 kpc radius and a superposition of axisymmetric and bisymmetric modes from 3 to 5 kpc radius) and a vertical component. However, the inferred ‘vertical field’ may be partly due to a galactic warp. We estimate the average total and regular magnetic field strengths as ≃6.4 and 2.5 μG, respectively. Generation of interstellar magnetic fields by turbulent gas motion in M 33 is indicated as the turbulent and magnetic energy densities are about equal.
Interplay of CR-driven galactic wind, magnetic field, and galactic dynamo in spiral galaxies
Authors: Krause Marita 
Published: April 2009

AbstractFrom our radio observations of the magnetic field strength and large-scale pattern of spiral galaxies of different Hubble types and star formation rates (SFR) we conclude that – though a high SFR in the disk increases the total magnetic field strength in the disk and the halo – the SFR does not change the global field configuration nor influence the global scale heights of the radio emission. The similar scale heights indicate that the total magnetic field regulates the galactic wind velocities. The galactic wind itself may be essential for an effective dynamo action.
Structure of magnetic fields in spiral galaxies
Authors: Kotarba Hanna , Lesch H. , Dolag K. , Naab T. , Johansson P. H. , Stasyszyn F. A. 
Published: April 2009

AbstractWe present a set of global, self-consistentN-body/SPH simulations of the dynamic evolution of galactic discs with gas and including magnetic fields. We have implemented a description to follow the ideal induction equation in the SPH part of the codeVine. Results from a direct implementation of the field equations are compared to a representation by Euler potentials, which pose a ∇ ċB-free description, a constraint not fulfilled for the direct implementation. All simulations are compared to an implementation of magnetic fields in the codeGadget. Starting with a homogeneous field we find a tight connection of the magnetic field structure to the density pattern of the galaxy in our simulations, with the magnetic field lines being aligned with the developing spiral pattern of the gas. Our simulations clearly show the importance of non-axisymmetry of the dynamic pattern for the evolution of the magnetic field.
3D MHD simulations of magnetic fields and radio polarization of barred galaxies
Authors: Kulesza-Żydzik B. , Kulpa-Dybeł K. , Otmianowska-Mazur K. , Kowal G. , Soida M. 
Published: April 2009

AbstractWe present results of three-dimensional, fully nonlinear MHD simulations of a large-scale magnetic field evolution in a barred galaxy. The model does not take into consideration the dynamo process. We find that the obtained magnetic field configurations are highly similar to the observed maps of the polarized intensity of barred galaxies, because the modeled vectors form coherent structures along the bar and spiral arms. Due to the dynamical influence of the bar the gas forms spiral waves which go radially outward. Each spiral arm forms the magnetic arm which stays much longer in the disk, than the gaseous spiral structure. Additionally the modeled total energy of magnetic field grows due to strong compression and shear of non-axisymmetrical bar flows and differential rotation, respectively.
Magnetic fields in irregular galaxies
Authors: Kepley Amanda , Wilcots Eric , Zweibel Ellen , Mühle Stefanie , Everett John , Robishaw Timothy , Heiles Carl , Klein Uli 
Published: April 2009

AbstractThe low masses of irregular galaxies change the behavior of their interstellar medium (ISM) compared to that of normal spirals, so the role of magnetic fields in the ISM in irregulars may be very different than in spirals. We present high-resolution and high-sensitivity observations of the magnetic fields of two irregular galaxies: NGC 4214 and NGC 1569.
Cosmic-ray driven dynamo in the medium of irregular galaxy
Authors: Siejkowski Hubert , Soida Marian , Otmianowska-Mazur Katarzyna , Hanasz Michał , Bomans Dominik 
Published: April 2009

AbstractWe investigate the cosmic ray driven dynamo in the interstellar medium of irregular galaxy. The observations (Chyży et al. 2000, 2003) show that the magnetic field in irregular galaxies is present and its value reaches the same level as in spiral galaxies. However the conditions in the medium of irregular galaxy are very unfavorable for amplification the magnetic field due to slow rotation and low shearing rate.In this work we present numerical model of the interstellar medium in irregular galaxies. The model includes magnetohydrodynamical dynamo driven by cosmic rays in the interstellar medium provided by random supernova explosions. We describe models characterized by different shear and rotation. We find that even slow galactic rotation with low shearing rate gives amplification of the magnetic field. Simulations have shown that high amount of the magnetic energy flow out off the simulation region becoming an efficient source of intergalactic magnetic fields.
Zeeman splitting in the diffuse interstellar medium–The Milky Way and beyond
Authors: Heiles Carl , Robishaw Timothy 
Published: April 2009

AbstractWe begin with a brief review of Zeeman-splitting fundamentals and the importance of circular polarization, i.e. Stokes V. We then turn to modern results in several areas, emphasizing the diffuse interstellar medium in the Galaxy. The median field in the Cold Neutral Medium is determined from HI absorption lines and is about 6 μG; the magnetic and turbulent pressures are comparable. Using HI emission lines the field has been mapped in several areas: the field reverses across the Orion Molecular Cloud; the 3-d field structure has been determined in the ρ Oph region; and in regions having shock-like morphology the field is generally stronger, strong enough to limit further compression. We briefly present new field measurements for: photo-dissociation regions at the edges of HII regions, determined from carbon recombination lines; Ultra Luminous Infrared Galaxies, from OH megamasers; and the 3C 286 damped Lyman-α absorption system, determined from the 21-cm line in absorption. We show the sidelobe response of the Green Bank Telescope, which is surprisingly severe and makes the telescope less than optimum for Zeeman-splitting measurements of HI emission lines. Finally, we compare two techniques for determining field strengths, i.e. Zeeman splitting and the Chandrasekhar-Fermi method, and show why the latter usually gives higher field strengths – and sometimes unrealistically high fields.
Measuring and calibrating galactic synchrotron emission
Authors: Reich Wolfgang , Reich Patricia 
Published: April 2009

AbstractOur position inside the Galaxy requires all-sky surveys to reveal its large-scale properties. The zero-level calibration of all-sky surveys differs from standard ‘relative’ measurements, where a source is measured in respect to its surroundings. All-sky surveys aim to include emission structures of all angular scales exceeding their angular resolution including isotropic emission components. Synchrotron radiation is the dominating emission process in the Galaxy up to frequencies of a few GHz, where numerous ground based surveys of the total intensity up to 1.4 GHz exist. Its polarization properties were just recently mapped for the entire sky at 1.4 GHz. All-sky total intensity and linear polarization maps from WMAP for frequencies of 23 GHz and higher became available and complement existing sky maps. Galactic plane surveys have higher angular resolution using large single-dish or synthesis telescopes. Polarized diffuse emission shows structures with no relation to total intensity emission resulting from Faraday rotation effects in the interstellar medium. The interpretation of these polarization structures critically depends on a correct setting of the absolute zero-level in Stokes U and Q.
Imaging polarimetry as a diagnostic tool
Authors: Gledhill Tim M. 
Published: April 2009

AbstractSome of the earliest polarimetric measurements made in astronomy were concerned with the polarization of the interstellar medium resulting from dust grains aligned in the Galactic magnetic field. More than 50 years later, polarimetry continues to be an important diagnostic of field structure on size scales ranging from planetary to galactic. The use of both linear and circular polarimetry at optical and infrared wavelengths can provide additional insights into the nature of dust particles, their alignment in magnetic fields and the field topology. Given the science benefits that polarimetry offers it is perhaps surprising that the continued existence of polarimetric facilities on current and next generation large telescopes needs to be ensured.
Measuring cosmic magnetic fields with very large telescopes
Authors: Kochukhov Oleg , Piskunov Nicolai 
Published: April 2009

AbstractWe review general properties and capabilities of the instrumentation employed to diagnose cosmic magnetic fields using medium-size and large optical telescopes. During the last decade these spectropolarimeters and high-resolution spectrographs have been successfully used to detect and characterize magnetic fields in stars across the H-R diagram. A new generation of high-resolution spectropolarimeters will benefit from the large collecting area of the future E-ELT and currently operating 8-m class telescopes. We review plans to develop spectropolarimeters for these very large telescopes and outline a number of science cases where new spectropolarimetric instrumentation is expected to play a key role.
A full-Stokes polarimeter for the GREGOR Fabry-Perot interferometer
Authors: Balthasar Horst , Bello González N. , Collados M. , Denker C. , Hofmann A. , Kneer F. , Puschmann K. G. 
Published: April 2009

AbstractOne of the first post-focus instruments of the new solar telescope GREGOR will be a Fabry-Perot spectrometer, which is an upgrade of the Göttingen Fabry-Perot interferometer at the Vacuum Tower Telescope (VTT) on Tenerife. This spectrometer is equipped with a full-Stokes polarimeter. The modulation is performed with two ferroelectric liquid crystals, one acting nominally as quarter-wave plate, and the other as half-wave plate. A modified Savart plate serves as polarimetric beam splitter. With the present liquid crystals, the optimum wavelength range of this polarimeter is between 580 and 660 nm. The spectro-polarimeter will benefit from the capabilities of the new telescope GREGOR which will provide a spatial resolution of about 0″.1 (75 km on the solar surface). Thus we will be able to investigate small magnetic features, and we will study their development with high cadence.
Detecting magnetic fields in large-scale structure with radio polarization
Authors: Brown Shea , Rudnick Lawrence , Farnsworth Damon 
Published: April 2009

AbstractWe present our attempts to detect magnetic fields in filamentary large-scale structure (LSS) by observing polarized synchrotron emission emitted by structure formation shocks. Little is known about the strength and order of magnetic fields beyond the largest clusters of galaxies, and synchrotron emission holds enormous promise as a means of probing magnetic fields in these low density regions. We report on observations taken at the Green Bank Telescope which reveal a possible Mpc extension to the Coma cluster relic. We also highlight the major obstacle that diffuse galactic foreground emission poses for any search for large-scale, low surface-brightness extragalactic emission. Finally we explore cross-correlation of diffuse radio emission with optical tracers of LSS as a means to statistically detecting magnetic fields in the presence of this confounding foreground emission.
Minimal Information About Sample Preparation for Phosphoproteomics
Authors: Carrascal Montserrat , Ovelleiro David , Gay Marina , Abian Joaquin 
Published: April 2009

AbstractThis guideline describes parameters and conditions involved in phosphopeptide sample preparation. It covers from the description and preparation of the cells and tissues to the fractionation and specific enrichment of phosphopeptides for MS analysis. The guideline is prepared in order to easily cope with many of the experimental designs used in phosphoproteomic studies. The document is subdivided as follows:1. General features2. Sample processing3. Protein Purification/Fractionation4. Peptide Purification/Fractionation5. Phosphopeptide enrichment
GENCODE: Creating a Validated Manually Annotated Geneset for the Whole Human Genome
Authors: Bignell A. , Frankish A. , Aken B. , Diekhans M. , Kokocinski F. , Lin M. , Tress M. , Van Baren J. , Barnes I. , Hunt T. , Carvalho-Silva D. , Davidson C. , Donaldson S. , Gilbert J. , Hart E. , Kay M. , Kinsella R. , Lloyd D. , Loveland J. , Mudge J. , Snow C. , Vamathevan J. , Wilming L. , Brent M. , Gerstein M. , Guigó R. , Harte R. , Kellis M. , Searle S. , Harrow J. , Hubbard T. 
Published: April 2009

AbstractThe Human and Vertebrate Analysis and Annotation (HAVANA) group at the Wellcome Trust Sanger Institute produced the manually annotated geneset for the Encyclopedia of DNA Elements (ENCODE) pilot project and, as part of the Gencode subgroup, are reprising this role in the scale up to cover the whole human genome. Our manual annotation is checked computationally and validated experimentally. Loci and transcripts predicted to be absent from the initial annotation are identified by comparison with a number of state-of-the-art algorithms for identifying exons, splice sites, transcripts and pseudogenes. Where novel features are confirmed the annotation is updated. Annotated coding transcripts are analysed to assess their coding potential by investigating patterns of conservation within the coding sequence (CDS) and comparing predicted secondary structures of annotated CDSs to similar proteins with solved structures. Annotated coding transcripts are also checked against the current set of human Consensus CDSs (CCDS) to check agreement with other participating centres (EBI, NCBI, & UCSC).An initial round of annotation and analysis of chromosomes 21 and 22 has shown that while HAVANA annotation is both comprehensive and robust, it has benefitted from computational review. 13 novel non-coding loci, 27 novel splice variants and 6 extensions to existing variants were identified, many of which were found using supporting EST/mRNA sequences that were not present at the time of initial annotation. Fewer than 10 annotated CDSs required reclassification, no CCDS sequences required updating and 26 novel pseudogene were added. The annotation of human chromosome 2 is complete and we are currently annotating chromosomes 3 and 7. Data from all members of Gencode is distributed via DAS and is now visible in our Zmap annotation interface, allowing assessment of computational predictions contemporaneous with first-pass gene annotation.
Evaluation of the quality of the North Sea herring assessment
Authors: Simmonds E. John 
Published: April 2009

Abstract
Simmonds, E. J. 2009. Evaluation of the quality of the North Sea herring assessment. – ICES Journal of Marine Science, 66: 1814–1822. The assessment of North Sea herring has been used to give advice on catch quota for more than 20 years. The data sources comprise acoustic surveys, International Bottom Trawl Surveys, Methot Isaacs–Kidd net post-larval surveys, larval surveys, and catch-at-age data. These sources and their uses are briefly reviewed, and the changes in the weighting attached to each index in the assessment over time are discussed. The performance of the assessment is examined both in historical and analytical retrospectives of spawning–stock biomass and fishing mortality, and in retrospective assessments of numbers by cohort. Increased length of the time-series, the use of a statistical model with appropriate weighting, and a more consistent management strategy have all contributed to the assessment becoming highly stable from one year to the next. The results presented lead to the conclusion that the assessments provide an excellent basis for the management of this stock.
How to collect verifiable length data on tuna from photographs: an approach for sample vessels
Authors: Chang Shui-Kai , Lin Ta-Te , Lin Ghung-Hui , Chang Hsiang-Yun , Hsieh Ching-Lu 
Published: April 2009

Abstract
Chang, S-K., Lin, T-T., Lin, G-H., Chang, H-Y., and Hsieh, C-L. 2009. How to collect verifiable length data on tuna from photographs: an approach for sample vessels. – ICES Journal of Marine Science, 66: 907–915. Length frequencies are essential data for fish stock assessments, particularly for longer-lived species. They are usually provided by commercial vessels, or by port sampling, observers, or sample-vessel programmes, but each of these has limitations. Collection by sample vessels might be the most balanced way if the data quality is verifiable. We introduce a photograph-based length-measurement approach for sample vessels to photograph fish images with a calibration board, using a regular digital camera to obtain length estimates that can be verified after the images are transformed to reduce errors of perspective distortions. We analyse this approach under ideal conditions, develop a set of objective criteria for choosing acceptable photographs from observers, and compare estimated lengths for bigeye tuna (Thunnus obesus) based on this approach with lengths measured by observers. The criteria can serve as guidelines for photographing: if images are captured following these guidelines, the approach shows the potential for obtaining cheaply a large quantity of length estimates that deviate around 3% (up and down) on average from the actual measurements taken by observers.
Expression Level ofABERRANT PANICLE ORGANIZATION1Determines Rice Inflorescence Form through Control of Cell Proliferation in the Meristem
Authors: Ikeda-Kawakatsu Kyoko , Yasuno Naoko , Oikawa Tetsuo , Iida Shigeru , Nagato Yasuo , Maekawa Masahiko , Kyozuka Junko 
Published: April 2009

AbstractTwo types of branches, rachis branches (i.e. nonfloral) and spikelets (i.e. floral), are produced during rice (Oryza sativa) inflorescence development. We previously reported that the ABERRANT PANICLE ORGANIZATION1 (APO1) gene, encoding an F-box-containing protein orthologous to Arabidopsis (Arabidopsis thaliana) UNUSUAL FLORAL ORGANS, suppresses precocious conversion of rachis branch meristems to spikelets to ensure generation of certain number of spikelets. Here, we identified four dominant mutants producing an increased number of spikelets and found that they are gain-of-function alleles of APO1. The APO1 expression levels are elevated in all four mutants, suggesting that an increase of APO1 activity caused the delay in the program shift to spikelet formation. In agreement with this result, ectopic overexpression of APO1 accentuated the APO1 gain-of-function phenotypes. In the apo1-D dominant alleles, the inflorescence meristem starts to increase in size more vigorously than the wild type when switching to the reproductive development phase. This alteration in growth rate is opposite to what is observed with the apo1 mutants that have a smaller inflorescence meristem. The difference in meristem size is caused by different rates of cell proliferation. Collectively, these results suggest that the level of APO1 activity regulates the inflorescence form through control of cell proliferation in the meristem.