bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing the size of a magnetosphere of a young solar-like star
Authors: Hamilton Catrina M. , Johns-Krull C. M. , Mundt R. , Herbst W. , Winn J. N.
Published: April 2009

We have obtained high resolution spectra of the pre-main sequence binary system KH 15D (V582 Mon) while the star is fully visible, fully occulted, and during several ingress and egress events over the course of five contiguous observing seasons. The Hα line profile is a standard probe of the magnetospheric accretion flows on young stars such as KH 15D. We use these time series data to map out the size of the magnetosphere and find that it changes size from one observing season to the next.
Numerical simulations of magnetized winds of solar-like stars
Authors: Vidotto Aline A. , Opher M. , Jatenco-Pereira V. , Gombosi T. I.
Published: April 2009

We investigate magnetized solar-like stellar winds by means of self-consistent three-dimensional (3D) magnetohydrodynamics (MHD) numerical simulations. We analyze winds with different magnetic field intensities and densities as to explore the dependence on the plasma-β parameter. By solving the fully ideal 3D MHD equations, we show that the plasma-β parameter is the crucial parameter in the configuration of the steady-state wind. Therefore, there is a group of magnetized flows that would present the same terminal velocity despite of its thermal and magnetic energy densities, as long as the plasma-β parameter is the same.
On MHD rotational transport, instabilities and dynamo action in stellar radiation zones
Authors: Mathis Stéphane , Brun A.-S. , Zahn J.-P.
Published: April 2009

Magnetic field and their related dynamical effects are thought to be important in stellar radiation zones. For instance, it has been suggested that a dynamo, sustained by a m = 1 MHD instability of toroidal magnetic fields (discovered by Tayler in 1973), could lead to a strong transport of angular momentum and of chemicals in such stable regions. We wish here to recall the different magnetic transport processes present in radiative zone and show how the dynamo can operate by recalling the conditions required to close the dynamo loop (BPol → BTor → BPol). Helped by high-resolution 3D MHD simulations using the ASH code in the solar case, we confirm the existence of the m = 1 instability, study its non-linear saturation, but we do not detect, up to a magnetic Reylnods number of 105, any dynamo action.
Direct detection of a magnetic field on the surface of slowly rotating giant stars
Authors: Aurière Michel , Konstantinova-Antova R. , Petit P. , Wade G. , Roudier T.
Published: April 2009

We present first results of the magnetic survey of a sample of slow rotating giant stars for which an X-ray emission or variations of CaII H & K lines have been already detected.
HD 232862: a magnetic and Lithium-rich giant field star
Authors: Lèbre Agnès , Palacios A. , do Nascimento J. D. , De Medeiros J. R. , Konstantinova-Antova R. , Kolev D. , Aurière M.
Published: April 2009

From spectropolarimetric data and spectral synthesis analysis, we report the serendipitous discovery of an unusually high lithium content field giant. HD 232862, classified as a G8II star, appears to be the first Lithium-rich field giant star hosting a surface magnetic field.
Zeeman-Doppler imaging of II Peg
Authors: Carroll Thorsten A. , Kopf Markus , Strassmeier Klaus G. , Ilyin Ilya , Tuominen Ilkka
Published: April 2009

We present Zeeman-Doppler images of the active K2 star II Peg for the years 2004 and 2007. The surface magnetic field was reconstructed with our new ZDI code iMap which provides a full polarized radiative transfer driven inversion to simultaneously reconstruct the surface temperature and magnetic vector field distribution. II Peg shows a remarkable large scale magnetic field structure for both years. The magnetic field is predominantly located at high latitudes and is arranged in active longitudes. A dramatic evolution in the magnetic field structure is visible for the two years, where a dominant and largely unipolar field in 2004 has changed into two distinct and large scale bipolar structures in 2007.
Magnetic Doppler imaging of II Peg
Authors: Kochukhov Oleg , Piskunov N. , Ilyin I. , Tuominen I.
Published: April 2009

Rotational modulation of the intensity and polarization spectra of magnetic stars offers a unique possibility to reconstruct the structure of surface magnetic fields and to investigate their relation to cool starspots. We have developed a new magnetic Doppler imaging code which aims at self-consistent temperature and magnetic mapping of cool active stars. Here we present magnetic Doppler imaging analysis of high-resolution circular polarization observations of the active star II Peg. We demonstrate that a self-consistent approach to magnetic inversion unveils stronger magnetic fields than found previously through disjoint analyses of polarization and intensity observations of active stars.
Discovery of fossil magnetic fields in the intermediate-mass pre-main sequence stars
Authors: Alecian Evelyne , Wade Gregg A. , Catala Claude
Published: April 2009

It is now well-known that the surface magnetic fields observed in cool, lower-mass stars on the main sequence (MS) are generated by dynamos operating in their convective envelopes. However, higher-mass stars (above 1.5 M⊙) pass their MS lives with a small convective core and a largely radiative envelope. Remarkably, notwithstanding the absence of energetically-important envelope convection, we observe very strong (from 300 G to 30 kG) and organised (mainly dipolar) magnetic fields in a few percent of the A and B-type stars on the MS, the origin of which is not well understood. In this poster we propose that these magnetic fields could be of fossil origin, and we present very strong observational results in favour of this proposal.
The surface magnetic fields of T Tauri stars
Authors: Hussain Gaitee A. J. , Cameron Andrew Collier , Jardine Moira , Donati Jean-Francois
Published: April 2009

We 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

We 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

In 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

Using 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

From 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

We 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

We 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

The 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

We 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

We 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

Our 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

Some 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

We 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

One 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

We 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.
Individuelle Lebensqualität von drogenabhängigen Patienten in einem Entzugsprogramm: Selbstbeurteilung in einer Drogenentzugs- und Übergangsstation für Erwachsene
Authors: Frei-Rhein Geneviève , Hantikainen Virpi
Published: April 2009

Mit dieser Untersuchung wurden zwei Ziele verfolgt: Erkenntnisse über die individuelle Lebensqualität (LQ) von drogenabhängigen Patienten (N = 30) während einem freiwilligen Aufenthalt in einer Drogenentzugs- und Übergangsstation in einem schweizerischen psychiatrischen Kontext zu gewinnen sowie die Veränderungen der individuellen LQ im zeitlichen Verlauf von drei Wochen zu untersuchen. Mittels dem halbstrukturierten Instrument «Schedule for the Evaluation of Individual Quality of Life: a Direct Weighting Procedure for Quality of Life Domains» wurden 30 Drogenabhängige (23 Männer, 7 Frauen) kurz nach Klinikeintritt und 16 von ihnen («Durchhalter») nach drei Wochen Klinikaufenthalt befragt. Die qualitativen Inhalte der insgesamt 46 Interviews wurden nach Morse und Field (1998) analysiert. Von den 269 individuell genannten Lebensqualitätsbereichen (LQB) kurz nach Klinikeintritt konnten 37 LQB abgeleitet und diese wiederum neun übergeordneten Themenbereichen zugeordnet werden. In den Interviews nach drei Wochen Klinikaufenthalt blieben die genannten übergeordneten Themenbereiche und LQB grundsätzlich gleich, es wurde aber ein LQB – «strukturelle Bedingungen», welcher sich dem übergeordneten Themenbereich «Belastungsfaktor» zuordnen lässt – zusätzlich generiert. Die Rangfolge einzelner übergeordneter Themenbereiche änderte sich. Der Median des globalen Lebensqualitätswerts (GLQ) aller 30 Teilnehmer kurz nach Klinikeintritt betrug 48.5 von max. 100. Dabei lag der Median für die 16 «Durchhalter» mit 57.7 wesentlich höher als für die 14 «drop outs» (39.9). Nach drei Wochen Klinikaufenthalt stieg der Median der «Durchhalter» auf 63.1. Es zeigte sich, dass Drogenabhängige im Vergleich zur Normalbevölkerung eine niedrigere körperliche oder psychische LQ, im Vergleich zu anderen psychiatrischen Patientengruppen jedoch eine ähnliche LQ aufweisen. Die Methode genoss bei den Teilnehmern eine hohe Akzeptanz und wurde als wenig belastend erlebt. Die Studie zeigte, dass LQ von drogenabhängigen Patienten individuell, multidimensional, dynamisch und komplex ist.
Importance of land use versus atmospheric information verified from cloud simulations from a frontier region in Costa Rica
Authors: Ray Deepak K. , Pielke Roger A. , Nair Udaysankar S. , Welch Ronald M. , Lawton Robert O.
Published: April 2009

Land‐use/land‐cover (LULC) change has been recognized as a key component in global climate change, and numerous climate modeling studies at regional to global scales document this. The research strategies have invariably been to first conduct baseline simulations of current conditions to evaluate model performance. Then simulation of regional climate with land cover changes (LCC) implemented within the model allows differences with the baseline simulation to be used as evidence of global to regional‐scale climate impacts of LCC. However, even state‐of‐the‐art regional climate models require two data sets to conduct reasonable baseline simulations. These are representative current land cover and atmospheric information over the study region. In frontier and developing areas (where most of the rapid land‐use conversion is taking place), these data sets are frequently unavailable and the errors in simulations are due to either inaccurate land cover, insufficient atmospheric information, nonrepresentative model physics, or a combination of one or more of the above. This study shows that in one frontier region, that surrounding the Cordillera de Tilarán of Costa Rica, the accuracy of simulating clouds decreases by 1% to 3% if default model land cover information is used. If the atmospheric data sets used are the ones usually available to researchers (with land cover information held constant), then the model accuracy is reduced by 21% to 25%. Model runs without updated land cover or atmospheric information reduce model accuracy slightly further. Precipitation comparisons also provide similar results. This study thus shows that the critically important data set for conducting accurate simulations is not land cover information but atmospheric information. Researchers may similarly get significant increase in the accuracy of their baseline simulations elsewhere by using radiosondes/rawinsondes over their study region. Finally, since atmospheric information is not available for different landscape scenarios, assessments of the relative role of LULC change will have to continue to rely on using the standard atmospheric data set and the acceptance that the use of more detailed atmospheric data to initialize and provide lateral boundary conditions would have reduced the uncertainties in such landscape sensitivity studies.
Seismic attenuation tomography of the Mariana subduction system: Implications for thermal structure, volatile distribution, and slow spreading dynamics
Authors: Pozgay Sara H. , Wiens Douglas A. , Conder James A. , Shiobara Hajime , Sugioka Hiroko
Published: April 2009

The anelastic structure of a subduction zone can place first‐order constraints on variations in temperature and volatile content. We investigate seismic attenuation across the western Pacific Mariana subduction system using data from the 2003–2004 Mariana Subduction Factory Imaging Experiment. This 11‐month experiment consisted of 20 broadband stations deployed on the arc islands and 58 semibroadband ocean bottom seismographs deployed across the fore arc, island arc, and back‐arc spreading center. We compute amplitude spectra for P and S arrivals from local earthquakes and invert for the path‐averaged attenuation for each waveform along with the seismic moment and corner frequency for each earthquake. Additionally, we investigate earthquake source parameter assumptions and frequency‐dependent exponents (α) ranging from 0 to 0.6. Tomographic inversion of nearly 3000 t* estimates (at α = 0.27) for 2‐D QP−1 and QP/QS structure shows a ∼75 km wide columnar‐shaped high‐attenuation anomaly with QP ∼ 43–60 beneath the spreading center that extends from the uppermost mantle to ∼100 km depth. A weaker high‐attenuation region (QP ∼ 56–70) occurs at depths of 50–100 km beneath the volcanic arc, and the high‐attenuation regions are connected at depths of 75–125 km. The subducting Pacific plate is characterized by low attenuation at depths greater than 100 km, but high attenuation is found in the plate between 50 and 100 km depth. The fore arc shows high attenuation near the volcanic arc and beneath the serpentinite seamounts in the outer fore arc. QS structure is less well resolved than QP because of a smaller data set, but QP/QS ratios are significantly less than 2 throughout the study region. As temperatures estimated from QS−1 are unusually high, we interpret the arc and wedge core anomalies as regions of high temperature with enhanced Q−1 due to hydration and/or melt, the slab and fore‐arc anomalies as indicative of slab‐derived fluids and/or large‐scale serpentinization, and the columnar‐shaped high QP−1 anomaly directly beneath the back‐arc spreading center as indicative of a narrow region of dynamic upwelling and melt production beneath the slow spreading ridge axis.
The source of infrasound associated with long‐period events at Mount St. Helens
Authors: Matoza Robin S. , Garcés Milton A. , Chouet Bernard A. , D'Auria Luca , Hedlin Michael A. H. , De Groot‐Hedlin Catherine , Waite Gregory P.
Published: April 2009

During the early stages of the 2004–2008 Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long‐period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic‐acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo‐acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and source configuration are considered. The simulations show that a shallow source buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from the source epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point source. The observations therefore require a more complex source process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the “valve” sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as recorded at an array 13.4 km to the NW of the volcano are attributed primarily to atmospheric boundary layer propagation effects, superimposed upon amplitude changes at the source.
Motions of gently sloping ground during earthquakes
Authors: Bardet Jean‐Pierre , Liu Fang
Published: April 2009

During past earthquakes, gently sloping ground surfaces have been observed to shift laterally over areas as large as a few square kilometers. These permanent downward motions have been attributed to temporary and partial reductions in shear strength of soil deposits (e.g., liquefaction), static gravity forces, and transient earthquake shakings. These motions, the amplitudes of which remain challenging to predict, have been frequently modeled using Newmark sliding blocks for ground that is statically stable and occasionally partially or completely loses its shear strength during earthquakes. This paper investigates in more details the deformations of gently sloping ground that becomes temporarily unstable under the combined effects of gravitational forces and earthquake shakings. Using a physical model, we propose two definitions of earthquake contributions to the displacement of gently sloping ground, which may include or not the effects of initial velocity. In both cases, Monte Carlo simulations reveal that motions of gently sloping ground are influenced by pulses of earthquake ground velocity for a wide range of reduction in soil shear strength, even for very severe loss of shear strength. For practical purposes, when large soil deposits become unstable during earthquakes, the analysis concludes that the motions of gently sloping ground are likely influenced by earthquake ground velocity.
Using Satellite Data to Investigate the 12 May 2008 Sichuan Earthquake, China
Authors: Pan Gang , Tang DanLing
Published: April 2009

The M 8.0 earthquake that struck Sichuan Province in southwestern China on 12 May 2008 was the most devastating earthquake in that country in the past 5 decades. At least 69,000 deaths have been confirmed and more than 374,000 people were injured, according to China's Ministry of Civil Affairs. Overall, more than 45.5 million people in 10 provinces and regions in China were affected by the earthquake. Landslides and rockfalls damaged or destroyed several mountain roads and railways and buried buildings in the Beichuan‐Wenchuan area of Sichuan Province, cutting off access to the region for several days (Figures 1a and 1b). Landslides also dammed several rivers, and the resultant creation of 36 barrier lakes (dangerous earthquake lakes) threatened about 700,000 people downstream.
Mineral Dust and Climate: Working Group on Dust and Climate Joint INQUA/QUEST Workshop; Villefranche‐sur‐Mer, France, 19–22 October 2008
Authors: Maher Barbara A. , Harrison Sandy P.
Published: April 2009

Mineral aerosol (referred to here as “dust”) is an active climate and paleoclimate system component that may significantly influence the radiative properties of the atmosphere, as well as ocean and atmospheric carbon dioxide (CO2) concentrations, through processes such as iron fertilization. The integrative, cross‐cutting examination of the role and significance of dust provides the rationale for the Dust Indicators and Records of Terrestrial and Marine Paleoenvironments (DIRTMAP) working group sponsored by the International Union of Quaternary Research and the Natural Environment Research Council's Quantifying and Understanding the Earth System (QUEST) program. The working group aims to initiate coordinated progress to improve the representation of dust properties in dust cycle models, with particular focus on dust mineralogy, such as the concentrations of iron oxides and oxyhydroxides as either nanoparticles or mineral coatings, and particle size distribution. These two sets of factors are potentially significant in assessing the effects of dust on both radiative forcing and biogeochemical cycling. The working group also aims to improve model simulation of dust source regions, the episodic nature of dust emissions, and amounts of dust deposition over the continents.
Constraining Carbon Cycle Feedback Using Paleodata: Palaeocarbon Modelling Intercomparison Project Kickoff Workshop; Totnes, United Kingdom, 26–28 January 2009
Authors: Abe‐Ouchi Ayako , Harrison Sandy P.
Published: April 2009

Climate‐induced changes in the terrestrial biosphere and the ocean modulate the release and uptake of carbon dioxide (CO2), and this, in turn, alters atmospheric composition and climate in a process called climate/carbon cycle feedback. The Coupled Carbon Cycle Climate Model Intercomparison Project (C4MIP), using models of the terrestrial and ocean carbon cycles in ocean‐atmosphere general circulation models, has shown that although the feedback is positive, its magnitude is highly uncertain (P. Friedlingstein et al., J. Clim., 19, 3337, 2006). It is important to quantify this feedback adequately because it affects the CO2 emissions consistent with any atmospheric CO2 stabilization.
Phillips Receives 2008 Whipple Award
Authors: Jakosky Bruce , Phillips Roger J.
Published: April 2009

Roger J. Phillips received the Whipple Award at the 2008 AGU Fall Meeting Honors Ceremony, held 17 December in San Francisco, Calif. The award recognizes an individual who has made an outstanding contribution in the field of planetary science.
Minimal Information About Sample Preparation for Phosphoproteomics
Authors: Carrascal Montserrat , Ovelleiro David , Gay Marina , Abian Joaquin
Published: April 2009

This 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

The 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.
Neutrophil Activation in Morbid Obesity, Chronic Activation of Acute Inflammation
Authors: Nijhuis Jeroen , Rensen Sander S. , Slaats Yanti , van Dielen Francois M.H. , Buurman Wim A. , Greve Jan Willem M.
Published: April 2009

Recent studies show that morbid obesity is associated with activation of the innate immune response. Neutrophil activation is a fundamental process in the innate immune response. Therefore, the activation state of neutrophils in severely obese subjects and the effect of bariatric surgery on neutrophil activation was evaluated. Neutrophil activation was assessed by measuring circulating concentrations of myeloperoxidase (MPO) and calprotectin in 37 severely obese and 9 control subjects (enzyme‐linked immunosorbent assay). Moreover, membrane expression of CD66b on circulating neutrophils was measured using flow cytometry in a group of seven severely obese and six control subjects. Immunohistochemical detection of MPO was performed in adipose and muscle tissue. Plasma MPO and calprotectin levels were significantly increased in severely obese subjects as compared to healthy controls, 27.1 ± 10.8 vs. 17.3 ± 5.5 ng/ml (P < 0.001) and 115.5 ± 43.5 vs. 65.1 ± 23.1 ng/ml (P < 0.001) for MPO and calprotectin, respectively. In line, CD66b expression was significantly increased in severely obese individuals, 177.3 ± 43.7 vs. 129.7 ± 9.2 (mean fluorescence intensity) (P < 0.01). Bariatric surgery resulted in decreased calprotectin, but MPO plasma levels remained elevated. Adipose and muscle tissue did not contain increased numbers of MPO expressing cells in severely obese individuals. These results point out that circulating neutrophils are activated to a greater extent in severely obese subjects. Our data support the finding that the innate immune system is activated in severely obese individuals. Moreover, because neutrophils have a short life span, this indicates that the chronic inflammatory condition associated with morbid obesity is characterized by a continuous activation of the innate immune system.
Are Obesity and Physical Activity Clustered? A Spatial Analysis Linked to Residential Density
Authors: Schuurman Nadine , Peters Paul A. , Oliver Lisa N.
Published: April 2009

The aim of this study was to examine spatial clustering of obesity and/or moderate physical activity and their relationship to a neighborhood's built environment. Data on levels of obesity and moderate physical activity were derived from the results of a telephone survey conducted in 2006, with 1,863 survey respondents in the study sample. This sample was spread across eight suburban neighborhoods in Metro Vancouver. These areas were selected to contrast residential density and income and do not constitute a random sample, but within each area, respondents were selected randomly. Obesity and moderate physical activity were mapped to determine levels of global and local spatial autocorrelation within the neighborhoods. Clustering was measured using Moran's I at the global level, Anselin's Local Moran's I at the local level, and geographically weighted regression (GWR). The global‐level spatial analysis reveals no significant clustering for the attributes of obesity or moderate physical activity. Within individual neighborhoods, there is moderate clustering of obesity and/or physical activity but these clusters do not achieve statistical significance. In some neighborhoods, local clustering is restricted to a single pair of respondents with moderate physical activity. In other neighborhoods, any moderate local clustering is offset by negative local spatial autocorrelation. Importantly, there is no evidence of significant clustering for the attribute of obesity at either the global or local level of analysis. The GWR analysis fails to improve significantly upon the global model—thus reinforcing the negative results. Overall, the study indicates that the relationship between the urban environment and obesity is not direct.
BMI and Rates of Suicide in the United States: An Ecological Analysis
Authors: Mukamal Kenneth J. , Wee Christina C. , Miller Matthew
Published: April 2009

BMI has been inversely associated with risk of completed suicide in several cohort studies, but putative mechanisms for this association and its generalizability throughout the United States are uncertain. We ascertained recent population‐based, state‐level data on rates of obesity, completed suicide (by method), firearm ownership, smoking, major depression, income, education, white race, and nonmetropolitan residence, compiled from federal agencies and surveys, and determined the adjusted population‐weighted correlations of statewide obesity rates with measures of completed and attempted suicide. Statewide prevalence of obesity was strongly inversely correlated with age adjusted suicide rate (multivariable‐adjusted r = −0.66; P < 0.001). The correlation was somewhat stronger for rates of nonfirearm‐related (r = −0.75; P < 0.001) than firearm‐related suicides (r = −0.53; P < 0.001), and was of similar magnitude as the positive correlations of firearm prevalence with suicide rate (r = 0.75; P < 0.001) or of obesity with prevalence of diabetes (r = 0.41; P = 0.006). In analyses of fatal and nonfatal suicidal acts, obesity rates were inversely correlated with rates of suicidal acts using firearms (r = −0.53; P = 0.02) and suffocation (r = −0.76; P < 0.001) but not other methods. Obesity rates were also inversely correlated with the case–fatality ratios of acts using poisoning (r = −0.51; P = 0.01). Thus, statewide rates of obesity are strongly inversely correlated with rates of completed suicide in multivariable analyses, a finding that appears to relate to fewer attempts by suffocation and a lower case–fatality ratio for poisonings, although the mechanism for the inverse correlation with firearm‐related suicides requires further elucidation.
High Energy Digestion Efficiency and Altered Lipid Metabolism Contribute to Obesity in BFMI Mice
Authors: Meyer Carola W. , Wagener Asja , Rink Nadine , Hantschel Claudia , Heldmaier Gerhard , Klingenspor Martin , Brockmann Gudrun A.
Published: April 2009

To constitute a valuable resource to identify individual genes involved in the development of obesity, a novel mouse model, the Berlin Fat Mouse Inbred line 860 (BFMI860), was established. In order to characterize energy intake and energy expenditure in obese BFMI860 mice, we performed two independent sets of experiments in male BFMI860 and B6 control mice (10 per line). In experiment 1, we analyzed body fat content noninvasively by dual‐energy X‐ray absorptiometry and measured resting metabolic rate at thermoneutrality (RMRt) and respiratory quotient (RQ) in week 6, 10, and 18. In a second experiment, energy digested (energy intake minus fecal energy loss) was determined by bomb calorimetry from week 6 through week 12. BFMI860 mice were heavier and had higher fat mass (final body fat content was 24.7% compared with 14.6% in B6). They also showed fatty liver syndrome. High body fat accumulation in BFMI860 mice was restricted to weeks 6–10 and was accompanied by hyperphagia, higher energy digestion, higher RQs, and abnormally high blood triglyceride levels. Lean mass–adjusted RMRt was not altered between lines. These results indicate that in BFMI860 mice, the excessive accumulation of body fat is associated with altered lipid metabolism, high energy intake, and energy digestion. Assuming that BFMI860 mice and their obese phenotypes are of polygenic nature, this line is an excellent model for the study of obesity in humans, especially for juvenile obesity and hyperlipidemia.