bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory simulations of astrophysical jets
Authors: Lebedev Sergey V. , Suzuki-Vidal Francisco , Ciardi Andrea , Bocchi Matteo , Bland Simon N. , Burdiak Guy , Chittenden Jerry P. , de Grouchy Phil , Hall Gareth N. , Harvey-Thompson Adam , Marocchino Alberto , Swalding George , Frank Adam , Blackman Eric G. , Camenzind Max 
Published: June 2011

AbstractCollimated outflows (jets) are ubiquitous in the universe, appearing around sources as diverse as protostars and extragalactic supermassive black holes. Jets are thought to be magnetically collimated, and launched from a magnetized accretion disk surrounding a compact gravitating object. We have developed the first laboratory experiment to address time-dependent, episodic phenomena relevant to the poorly understood jet acceleration and collimation region (Ciardi et al., 2009). The experiments were performed on the MAGPIE pulsed power facility (1.5 MA, 250 ns) at Imperial College. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. The results provide a unique view of the possible transition from a relatively steady-state jet launching to the observed highly structured outflows.
Anomalous momentum transport in astrophysical return-current beam plasmas - the two-dimensional electromagnetic case
Authors: Lee Kuang Wu , Büchner Jörg 
Published: June 2011

AbstractAnomalous momentum transport in a typical astrophysical return-current beam plasma system is studied by means of two-dimensional PIC code simulations. A forward going hot electron beam compensated by a cold return beam is considered. A linear dispersion analysis predicts the linerarly unstable wave modes. Our simulation reveals that the nonlinerly generated waves and the consequent wave-particle interactions cause the electron heating and the relaxation of the electron drifts. Both, the developments of electrostatic and electromagnetic waves are analyzed as well as the roles they play in energy conversion. In particular it is found that the relaxation of electron drifts is stronger if the electromagnetic turbulence is taken into account.
Some Properties of prominence eruption associated CMEs during 1996-2009
Authors: Mittal Nishant 
Published: June 2011

AbstractSolar prominences can be viewed as pre-eruptive states of coronal mass ejections (CMEs). Eruptive prominences are the phenomena most related to CMEs observed in the lower layers of the solar atmosphere. We have made a comprehensive statistical study on the CMEs associated with prominence eruptions. We have examined the distribution of CMEs speed and acceleration for prominence eruptions associated CMEs. We also examine the speed-acceleration correlation for these events and there is no correlation between speed and acceleration. The mean angular width is almost similar to normal CMEs. The number variation during solar cycle of prominence activities is similar to the sunspot cycle.
Exploiting solar wind time series correlation with magnetospheric response by using an hybrid neuro-wavelet approach
Authors: Napoli Christian , Bonanno Francesco , Capizzi Giacomo 
Published: June 2011

AbstractThe studies about the Sun rise a strong interest regarding modifications caused by the solar activity on the Earth. For almost a century in literature was discussed the problem of forecasting and analysis of the space weather, which in his definition covers both the near-earth space and the biospheric affection due to the environmental interaction with the Sun. In particular in the last years increased the attention for magnetospheric response in conjunction with the technological infrastructure and the biosphere itself. This to prevent i.e. spacecraft failures or possible treats to human health. Since the main effect of the activity of the Sun is the solar wind, rises the aim to found a correlation between itself and the localized variations induced on the magnetosphere being the purpose to predict long-term variation of the magnetic field from solar wind time series. As recently proposed for solar wind forecasting, an hybrid approach will be here used than joining the wavelet analysis with the prediction capabilities of recurrent neural networks with an adaptive amplitude activation function algorithm in order to avoid the need to standardize or rescaling the input signal and to match the exact range of the activation function.
CME evolution and 3D reconstruction with STEREO Data
Authors: Orlando A. , Zuccarello F. , Romano P. , Zuccarello F. P. , Mierla M. , Spadaro D. , Ventura R. 
Published: June 2011

AbstractWe describe a CME event, occurred in NOAA 11059 on April 3 2010, using STEREO and MDI/SOHO data. We analyze the CME evolution using data provided by SECCHI-EUVI and COR1 onboard STEREO satellites, and we perform a 3D reconstruction of the CME using the LCT-TP method. Using MDI/SOHO line-of-sight magnetograms we analyze the magnetic configuration of NOAA 11059 and we determine the magnetic helicity trend.
Modeling circumstellar envelope with advanced numerical codes
Authors: Procopio P. , De Rosa A. , Burigana C. , Umana G. , Trigilio C. 
Published: June 2011

AbstractWe propose a modeling study on the formation and evolution of the Circumstellar Envelopes (CSEs) of a sample of selected radio-loud objects, based on an innovative interaction between two codes widely used by the scientific community, but in different fields. CLOUDY (Ferland et al. 1998) is a widely used code to model the spectral energy distribution (SED) of the several objects characterized by clouds of gas heated and ionized by a central object. CosmoMC (Lewis & Bridle 2002) instead is usually used for exploring cosmological parameter space. We investigate here on the exploitation of the sampling performance of the Markov-Chain Monte-Carlo (MCMC) engine of CosmoMC to search for a best fit model of the considered objects through the spectral synthesis capacity of CLOUDY.
Collisionless shocks and particle acceleration: Lessons from studies of heliospheric shocks
Authors: Terasawa Toshio 
Published: June 2011

AbstractAcceleration processes at astrophysical collisionless shocks are reviewed with a special emphasis on the importance of in situ observations of heliospheric shocks. Topics to be included are nonlinear reaction of shock acceleration process, effect of neutral particles, and electron acceleration.
Quasi-periodic oscillations in solar X-ray sources
Authors: Mészárosová Hana , Karlický Marian , Fárník František 
Published: June 2011

AbstractWe have searched for quasi-periodic oscillations in the hard X-ray emission of solar flares. We have selected 14 flare events which were divided into two groups: a) the events with the X-ray sources located at the flare loop footpoints and b) the events with the X-ray source above the solar limb, i.e. with the loop-top X-ray source. We found that while in the case with the footpoints X-ray sources the quasi-periods of the recorded oscillations were in the interval 2–380 s, in the events with loop-top sources only the quasi-periods longer than 50 s were recognized. These results are probably connected with the MHD oscillation modes of the flaring loop. While the long periods, which are dominant in loop-top sources, are produced by acoustic oscillations along the whole long loop, in the layers close to the loop footpoints also the MHD wave modes in shorter structures with shorter periods are generated.
An overview of thePlanckmission
Authors: Mandolesi N. , Burigana C. , Gruppuso A. , Procopio P. , Ricciardi S. 
Published: June 2011

AbstractThis paper provides an overview of the ESAPlanckmission and its scientific promises.Planckis equipped with a 1.5–m effective aperture telescope with two actively-cooled instruments observing the sky in nine frequency channels from 30 GHz to 857 GHz: the Low Frequency Instrument (LFI) operating at 20 K with pseudo-correlation radiometers, and the High Frequency Instrument (HFI) with bolometers operating at 100 mK. After the successful launch in May 2009,Planckhas already mapped the sky twice (at the time of writing this review) with the expected behavior and it is planned to complete at least two further all-sky surveys. The first scientific results, consisting of an Early Release Compact Source Catalog (ERCSC) and in about twenty papers on instrument performance in flight, data analysis pipeline, and main astrophysical results, will be released on January 2011. The first publications of the main cosmological implications are expected in 2012.
The EST project
Authors: Zuccarello Francesca ,   the EST team
Published: June 2011

AbstractEST European Solar Telescope is a pan-european project, presently in its Conceptual Design Study financed by the European Commission in the framework of FP7, involving 29 partners, from 14 different countries. The EST project is aimed at the realization of a 4-m class telescope, characterized by an optical design and a set of instruments optimized for extremely high resolution imaging and spectropolarimetric observations from near UV to NIR. EST will be four times larger than any existing high resolution solar telescope and it is designated with the highest priority among the ground-based, medium term (2016-2020) new projects in the ASTRONET Roadmap (Panel C). The EST instruments will measure fundamental astrophysical processes at their intrinsic scales in the Sun's atmosphere to establish the mechanism of magnetic field generation and removal, and of energy transfer from the surface to the upper solar atmosphere and eventually to the whole heliosphere. The conceptual Design Study started on February 2008 and will finish during 2011. EST will be operational at the same time as major ESA and NASA space missions aimed at studying solar activity.
Global MHD simulations of disk-magnetosphere interactions: accretion and outflows
Authors: Romanova M. M. , Lovelace R. V. E. , Ustyugova G. V. , Koldoba A. V. 
Published: June 2011

AbstractWe outline recent progress in understanding the accretion of plasma to rotating magnetized stars obtained from global axisymmetric (2D) and 3D magnetohydrodynamic (MHD) simulations in three main areas: (1.) Formation of jets from disk accretion onto rotating magnetized stars: From simulations where the viscosity and magnetic diffusivity within the disk are described by alpha models, we find long-lasting conical outflows/jets from the disk/magnetosphere boundary in both the case where the star is slowly rotating and where it is rapidly rotating (the “propeller regime”). Most of the mass flux in the outflows is in a hollow cone but inside this cone there is a low-density high-velocity magnetically dominated flow along the open polar field lines of the star. The outflows occur under conditions where the poloidal magnetic flux of the star is bunched up by the accretion disk near the disk/magnetosphere boundary. Recent simulations show that the conical outflows become well-collimated for axial distances of ≲ 20 times the inner disk radius. Exploratory 3D simulations show that conical winds are axisymmetric about the rotational axis (of the star and the disk), even when the dipole field of the star is significantly misaligned. (2.) Formation of intrinsically one-sided jets from disk accretion to rotating magnetized stars: There is strong observational evidence for an asymmetry between the approaching and receding jets from a number of young stars. We discuss the first MHD simulations of the formation asymmetric or one-sided jets arising from disk accretion to a rotating star with an asymmetric (dipole plus quadrupole) magnetic field. (3.) Global axisymmetric and 3D simulations of the magnetorotational instability (MRI) in disk accretion onto magnetized stars: In the axisymmetric simulations we observe cases where there is episodic or quasi-periodic burst of accretion similar to that observed in one X ray source. In 3D MHD simulations of accretion onto stars with tilted dipole fields using our Godunov-type code based on the “cubed sphere” grid we find that the density distribution is much less smooth than in the case of the laminar accretion flow described by α–viscosity. Instead, large turbulent cells dominate the flows and are strongly elongated in the azimuthal direction.
Recent results from simulations of the magnetorotational instability
Authors: Stone James M. 
Published: June 2011

AbstractThe nonlinear saturation of the magnetorotational instability (MRI) is best studied through numerical MHD simulations. Recent results of simulations that adopt the local shearing box approximation, and fully global models that follow the entire disk, are described. Outstanding issues remain, such as a first-principles understanding of the dynamo processes that control saturation with no net magnetic flux. Important directions for future work include a better understanding of basic plasma processes, such as reconnection, dissipation, and particle acceleration, in the MHD turbulence driven by the MRI.
Decay of trefoil and other magnetic knots
Authors: Candelaresi Simon , Del Sordo Fabio , Brandenburg Axel 
Published: June 2011

AbstractTwo setups with interlocked magnetic flux tubes are used to study the evolution of magnetic energy and helicity on magnetohydrodynamical (MHD) systems like plasmas. In one setup the initial helicity is zero while in the other it is finite. To see if it is the actual linking or merely the helicity content that influences the dynamics of the system we also consider a setup with unlinked field lines as well as a field configuration in the shape of a trefoil knot. For helical systems the decay of magnetic energy is slowed down by the helicity which decays slowly. It turns out that it is the helicity content, rather than the actual linking, that is significant for the dynamics.
A Natural Hedge for Equity Indexed Annuities
Authors: Bernard Carole , Boyle Phelim P. 
Published: June 2011

AbstractEquity linked products are popular in many countries. These contracts generally provide a guaranteed return combined with some participation in the market performance, often computed using a complicated formula. Hedging these contracts often presents a real challenge for insurers in particular during a financial crisis. In this paper, we explain how insurers can benefit from selling a pool of different contracts with different sensitivities to certain key variables to reduce risk exposure. We show how they can diversify their menu of policy designs to stabilize the market value of their liabilities against changes in the market volatility and against estimation error in the volatility parameter. We illustrate the methodology with specific examples of equity annuity contracts with opposite sensitivities to vega risk.
THE EXPRESSIVE POWER OF MEMORY LOGICS
Authors: ARECES CARLOS , FIGUEIRA DIEGO , FIGUEIRA SANTIAGO , MERA SERGIO 
Published: June 2011

We investigate the expressive power of memory logics. These are modal logics extended with the possibility to store (or remove) the current node of evaluation in (or from) a memory, and to perform membership tests on the current memory. From this perspective, the hybrid logic ℋℒ (↓), for example, can be thought of as a particular case of a memory logic where the memory is an indexed list of elements of the domain.This work focuses in the case where the memory is a set, and we can test whether the current node belongs to the set or not. We prove that, in terms of expressive power, the memory logics we discuss here lie between the basic modal logic ${\cal K}$ and ℋℒ (↓). We show that the satisfiability problem of most of the logics we cover is undecidable. The only logic with a decidable satisfiability problem is obtained by imposing strong constraints on which elements can be memorized.
Assisting natural forest regeneration in Northern Ethiopia: one intervention is not enough
Authors: Aerts Raf , November Eva , Hermy Martin , Deckers Jozef , Haile Mitiku , Muys Bart 
Published: June 2011

AbstractManagement strategies aimed at rehabilitating degraded and cleared forests often rely on temporary or permanent exclusion of herbivores (wild animals, livestock or both). But in many cases, this simple management technique is not sufficient to induce ecosystem restoration: many negative effects keep the ecosystem in a suboptimal, low biomass state. The presence of such stable states requires restoration measures to act on multiple stress factors simultaneously.Compensating for all limiting factors is neither practically nor economically feasible. But detailed knowledge about the autoecology of tree species – i.e. their site requirements, regeneration strategies and recruitment dynamics – may be used to tailor management to the most pertinent problems. Here we illustrate this approach with results from forest restoration experiments in grazing exclosures in northern Ethiopia using African wild olive (Olea europaea ssp. cuspidata) as a representative Afromontane climax species.The recruitment of African wild olive is affected by seed limitation, restricted seed dispersal and germination and survival limitation. The exclusion of grazing animals as a single measure to restore forest is not enough. Degraded grazing land moves into a state dominated by persistent shrubs, arresting forest succession and discouraging local stakeholders. Direct sowing or planting of seedlings in fertile patches under selected pioneer shrubs, however, may help to overcome this form of bush encroachment, in particular during years with an above-average rainfall.
The variant call format and VCFtools
Authors: Danecek Petr , Auton Adam , Abecasis Goncalo , Albers Cornelis A. , Banks Eric , DePristo Mark A. , Handsaker Robert E. , Lunter Gerton , Marth Gabor T. , Sherry Stephen T. , McVean Gilean , Durbin Richard ,   1000 Genomes Project Analysis Group
Published: June 2011

Abstract
Summary: The variant call format (VCF) is a generic format for storing DNA polymorphism data such as SNPs, insertions, deletions and structural variants, together with rich annotations. VCF is usually stored in a compressed manner and can be indexed for fast data retrieval of variants from a range of positions on the reference genome. The format was developed for the 1000 Genomes Project, and has also been adopted by other projects such as UK10K, dbSNP and the NHLBI Exome Project. VCFtools is a software suite that implements various utilities for processing VCF files, including validation, merging, comparing and also provides a general Perl API.
Availability: http://vcftools.sourceforge.net
Contact: rd@sanger.ac.uk
The role of fisheries data in the development evaluation and impact assessment in support of European fisheries plans
Authors: Simmonds E. J. , Döring R. , Daniel P. , Angot V. 
Published: June 2011

Abstract
Simmonds, E. J., Döring, R., Daniel, P., and Angot, V. 2011. The role of fisheries data in the development evaluation and impact assessment in support of European fisheries plans. – ICES Journal of Marine Science, 68: 1689–1698. The European Commission has two formal requirements for developing multi-annual management plan policies: evaluation of the past performance of existing plans and impact assessments (IAs) of the potential benefits of new proposals. The new policies require the evaluation of fishery management in terms of three specific criteria: (i) effectiveness, i.e. the best method to achieve the objectives; (ii) efficiency, the cost-effectiveness, and proportionality; and (iii) consistency, i.e. limiting trade-offs across economic, social, and environmental domains. To develop policy, there is a need to collect relevant information, then to conduct appropriate analyses that provide documentation to support the policy objectives. This paper discusses the data requirements for good environmental, economic, and social understanding of fishery dynamics and management, describing how fishery data are currently linked to the analytical and management evaluation process using examples from 2009 and 2010. The type of information currently used is considered, along with the timetable of data availability, and its effect on historical evaluation and IAs, which are now formally required when any changes to legislation are proposed in the European Union, including following stakeholder consultation. The possibilities and future needs for such data are discussed.
ROP GTPases Act with the Receptor-Like Protein PAN1 to Polarize Asymmetric Cell Division in Maize
Authors: Humphries John A. , Vejlupkova Zuzana , Luo Anding , Meeley Robert B. , Sylvester Anne W. , Fowler John E. , Smith Laurie G. 
Published: June 2011

AbstractPlant Rho family GTPases (ROPs) have been investigated primarily for their functions in polarized cell growth. We previously showed that the maize (Zea mays) Leu-rich repeat receptor-like protein PANGLOSS1 (PAN1) promotes the polarization of asymmetric subsidiary mother cell (SMC) divisions during stomatal development. Here, we show that maize Type I ROPs 2 and 9 function together with PAN1 in this process. Partial loss of ROP2/9 function causes a weak SMC division polarity phenotype and strongly enhances this phenotype in pan1 mutants. Like PAN1, ROPs accumulate in an asymmetric manner in SMCs. Overexpression of yellow fluorescent protein-ROP2 is associated with its delocalization in SMCs and with aberrantly oriented SMC divisions. Polarized localization of ROPs depends on PAN1, but PAN1 localization is insensitive to depletion and depolarization of ROP. Membrane-associated Type I ROPs display increased nonionic detergent solubility in pan1 mutants, suggesting a role for PAN1 in membrane partitioning of ROPs. Finally, endogenous PAN1 and ROP proteins are physically associated with each other in maize tissue extracts, as demonstrated by reciprocal coimmunoprecipitation experiments. This study demonstrates that ROPs play a key role in polarization of plant cell division and cell growth and reveals a role for a receptor-like protein in spatial localization of ROPs.