12,346 research outputs found
Morphological evolution of a 3D CME cloud reconstructed from three viewpoints
The propagation properties of coronal mass ejections (CMEs) are crucial to
predict its geomagnetic effect. A newly developed three dimensional (3D) mask
fitting reconstruction method using coronagraph images from three viewpoints
has been described and applied to the CME ejected on August 7, 2010. The CME's
3D localisation, real shape and morphological evolution are presented. Due to
its interaction with the ambient solar wind, the morphology of this CME changed
significantly in the early phase of evolution. Two hours after its initiation,
it was expanding almost self-similarly. CME's 3D localisation is quite helpful
to link remote sensing observations to in situ measurements. The investigated
CME was propagating to Venus with its flank just touching STEREO B. Its
corresponding ICME in the interplanetary space shows a possible signature of a
magnetic cloud with a preceding shock in VEX observations, while from STEREO B
only a shock is observed. We have calculated three principle axes for the
reconstructed 3D CME cloud. The orientation of the major axis is in general
consistent with the orientation of a filament (polarity inversion line)
observed by SDO/AIA and SDO/HMI. The flux rope axis derived by the MVA analysis
from VEX indicates a radial-directed axis orientation. It might be that locally
only the leg of the flux rope passed through VEX. The height and speed profiles
from the Sun to Venus are obtained. We find that the CME speed possibly had
been adjusted to the speed of the ambient solar wind flow after leaving COR2
field of view and before arriving Venus. A southward deflection of the CME from
the source region is found from the trajectory of the CME geometric center. We
attribute it to the influence of the coronal hole where the fast solar wind
emanated from.Comment: ApJ, accepte
Flow interaction between a streamwise oscillating cylinder and a downstream stationary cylinder
In this paper, we present some experimental results about the physical effects of a cylinderâs streamwise oscillation motion on a downstream one in a tandem arrangement. The upstream cylinder undergoes a controlled simple harmonic oscillation at amplitudes A/d = 0.2â0.8, where d is the cylinder diameter, and the frequency ratio of fe/fsfe/fs = 0â3.0, where fefe is the cylinder oscillation frequency and fsfs is the natural frequency of vortex shedding from a single stationary cylinder. Under these conditions, the vortex shedding is locked to the controlled oscillation motion. Flow visualisation using the planar laser-induced fluorescence and qualitative measurements using hot-wire anemometry reveal three distinct flow regimes behind the downstream cylinder. For fe/fs>(fe/fs)cfe/fs>(fe/fs)c , where (fe/fs)c(fe/fs)c is a critical frequency ratio which depends on A/d and Reynolds number Re, a so-called SA-mode occurs. The upstream oscillating cylinder generates binary vortices symmetrically arranged about the centreline, each containing a pair of counter-rotating vortices, and the downstream cylinder sheds vortices alternately at 0.5fe0.5fe . For 0.7â1.
Agronomic practices influence soil biodiversity with strong feedback to plant growth
Non-Peer Reviewe
An empirical analysis of the influence of macroeconomic determinants on World tourism demand
This paper considers three econometric models to determine the relationship between macroeconomic variables and tourism demand. Tourism demand is measured by the inbound visitor's population and also by on-the-ground expenditures. Macroeconomic determinants include the exchange rate, the relative domestic prices, and the World GDP per capita.
The database is an unbalanced panel of 218 countries over the period 1995-2012. There is evidence that an increase in the World's GDP per capita, a depreciation of the national currency, and a decline of relative domestic prices do help boosting the number of arrivals
and the correspondent expenditure level. The World's GDP per capita is more relevant when explaining arrivals, but relative prices become more important when we use expenditures as the proxy for tourism demand. In particular, we cannot reject the hypothesis of a relative prices unitary elasticity of expenditures. Additionally, we have also partitioned our data by
income level and by continent. Results are robust in the first partition, but less robust in the second, although the main conclusions still hold.info:eu-repo/semantics/acceptedVersio
Towards run-time monitoring of web services conformance to business-level agreements
Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable process-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specification, QoS and run-time verification. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This is a position paper towards defining these goals
Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets
Motivated by the recent discovery of a low temperature spin liquid phase in
layered organic compound -(ET)Cu(CN) which becomes a
superconductor under pressure, we examine the phase transition of Mott
insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an
anisotropic triangular lattice. We use a renormalized mean field theory to
study the Gutzwiller projected BCS wavefucntions. The half filled electron
system is a Mott insulator at large on-site repulsion , and is a
superconductor at a moderate . The symmetry of the SC state depends on the
anisotropy, and is gapful with symmetry near the
isotropic limit and is gapless with symmetry at small anisotropy
ratio.Comment: 6 pages, 5 figure
Where do They Head for University Studies? The University Destinations of Chinese IBDP Graduates: A Study of the International Baccalaureate Diploma Program in China
Paper PresentationConference theme: Educational Reform and Social Change: East-West DialogueOver the last decade, the number of IB programs adopted by schools around the world has
dramatically increased by almost 400% (IB, 2009; Lee et al., in-press). In recent years China has also
evidenced an impressive gain in the number of schools adopting IB programs in general and the DP in
particular. Specifically, as of 2011, there were 50 IB schools authorized for the implementation of the
DP in China. Of these, 43 schools have been authorized since 2003 (IB, 2012), illustrating the fast
growth of IBDP schools in China in recent years. Despite such fast growth (and by implication,
popularity) of the IBDP schools in China, empirical studies exploring the impact of Chinese IBDP
studentsâ learning outcomes in terms of their university matriculation to foreign universities seems to
be almost nonexistent. With this in mind, the primary goal of this proposal is to document the patterns
of university destination of IBDP graduates in China over time. To this end, our analysis centers on
the following overarching question: Where have Chinese students who previously graduated from the
50 IB schools been educated? Alongside the focus of the main question, we seek answers to more
specific questions: Are there any trends in their university destinations in terms of geographical region
or university prestige (by ranking)? Are there any significant differences in studentsâ enrolment in
foreign universities before or after the 50 IB schoolsâ adoption of the DP (in the case that the 50 IB
schools implemented different international programs other than the DP before they adopted the IB)?
Does the adoption of the DP contribute to the growth (rate) of DP graduates enrolled in foreign
universities? To investigate these questions, we adopt a theoretical framework from research of
international student mobility. Specifically, we focus on internal and external forces (Altbach,
Reisberg & Rumbley, 2009; Li & Bray, 2007) that influence IB graduatesâ international flow in terms
of university destination. We employ a sequential explanatory design (Creswell, Plano, Gutmann, &
Hanson, 2003). As part of the mixed-methods research project, we plan to collect longitudinal data on
DP graduatesâ destinations for university study since the adoption of the DP. A series of quantitative
analysis (e.g., descriptive trend analysis, pre/post comparison âbefore and afterâ the 50 IB schoolsâ
adoption of the DP, and longitudinal analysis using piecewise modeling) will be employed to
determine trends and patterns in terms of university matriculation of the 50 schools over time. As first
of its kind, this study will evidence the impact of the DP on student preparation for university studies
abroad. In addition, the dataset may be employed for broader purposes (e.g., program development or
evaluation) within the IB and the community of schools in China or East Asian countries.published_or_final_versio
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