bluuebunny/crossref_metadata_2025_split huggingface dataset:
INTEGRATED PID CONTROLLER DESIGN FOR AN UNMANNED AERIAL VEHICLE WITH STATIC STABILITY
Authors: LI R. , SHI Y. J. , XU H. L. 
Published: July 2013

AbstractThis paper presents an integrated guidance and control (IGC) design method for an unmanned aerial vehicle with static stability which is described by a nonlinear six-degree-of-freedom (6-DOF) model. The model is linearized by using small disturbance linearization. The dynamic characteristics of pitching mode, rolling mode and Dutch rolling mode are obtained by analysing the linearized model. Furthermore, an IGC design procedure is also proposed in conjunction with a proportional–integral–derivative (PID) control method and fuzzy control method. A PID controller is applied in the control loop of the elevator and aileron, and the attitude angle and attitude angular velocity are used as compensation feedback, giving a simple and low-order control law. A fuzzy control method is applied to perform the cross-coupling control of rolling and yawing. Finally, the 6-DOF simulation shows the effectiveness of the developed method.
Determinants of subquotients of Galois representations associated with
abelian varieties
Authors: Larson Eric , Vaintrob Dmitry 
Published: July 2013

AbstractGiven an abelian variety $A$ of dimension $g$ over a number field $K$, and a prime $\ell $, the ${\ell }^{n} $-torsion points of $A$ give rise to a representation ${\rho }_{A, {\ell }^{n} } : \mathrm{Gal} ( \overline{K} / K)\rightarrow {\mathrm{GL} }_{2g} ( \mathbb{Z} / {\ell }^{n} \mathbb{Z} )$. In particular, we get a mod-$\ell $representation ${\rho }_{A, \ell } : \mathrm{Gal} ( \overline{K} / K)\rightarrow {\mathrm{GL} }_{2g} ({ \mathbb{F} }_{\ell } )$ and an $\ell $-adic representation ${\rho }_{A, {\ell }^{\infty } } : \mathrm{Gal} ( \overline{K} / K)\rightarrow {\mathrm{GL} }_{2g} ({ \mathbb{Z} }_{\ell } )$. In this paper, we describe the possible determinants of
subquotients of these two representations. These two lists turn out to be remarkably
similar.Applying our results in dimension $g= 1$, we recover a generalized version of a theorem of Momose on isogeny
characters of elliptic curves over number fields, and obtain, conditionally on the
Generalized Riemann Hypothesis, a generalization of Mazur’s bound on rational
isogenies of prime degree to number fields.
On the role of asymmetries in the reversal of the solar magnetic field
Authors: Brun A. S. , Derosa M. L. , Hoeksema J. T. 
Published: July 2013

AbstractWe study how the solar magnetic field evolves from antisymmetric (dipolar) to symmetric (quadrupolar) state during the course of its 11-yr cycle. We show that based on equatorial symmetries of the induction equation, flux transport solar mean field dynamo models excite mostly the antisymmetric (dipolar) family whereas a decomposition of the solar magnetic field data reveals that both families should be excited to similar amplitude levels. We propose an alternative solar dynamo solution based on North-South asymmetry of the meridional circulation to better reconcile models and observations.
Convective mechanism of amplification and structuring of magnetic fields
Authors: Getling A. V. , Kolmychkov V. V. , Mazhorova O. S. 
Published: July 2013

AbstractMagnetoconvection in a horizontal layer of incompressible fluid is simulated numerically. The initial magnetic field is assumed to be uniform and horizontal. The interaction of quasi-ordered cellular convection with the magnetic field is shown to be able to produce bipolar (and also diverse more complex) configurations of a substantially amplified magnetic field. The operation of this mechanism, which can be regarded as a modification of the mechanism suggested by Tverskoi (1966), is controlled by the very topology of the cellular flow, should be manifest on various spatial scales, and does not require strong initial fields. Magnetic configurations develop both in the central parts of convection cells, where circulatory fluid motion “winds” magnetic field lines, and in the network formed by their peripheral regions due to the “sweeping” of magnetic field lines.
Magnetic helicity as a probe of magnetic flux-tube dynamics in the solar interior
Authors: Sakurai Takashi , Gao Yu , Kuzanyan Kirill 
Published: July 2013

AbstractMagnetic helicity (volume integral of the product of the magnetic field vectorBand the vector potentialA), or its proxy, the current helicity at the surface (surface integral ofB·JorBzJz), is an important quantity which characterizes the helical nature of solar magnetic fields. The current helicity on the Sun shows a tendency, though with large dispersion, that it is positive in the southern hemisphere and negative in the northern hemisphere (the helicity sign rule). However, there are indications that the helicity sign rule may be reversed at activity minimum periods. We will discuss the significance of this property by focusing on the statistical distributions of helicity whether its dispersion follows Gaussian distribution or not.
Topological constraints on magnetic field relaxation
Authors: Candelaresi Simon , Brandenburg Axel 
Published: July 2013

AbstractMagnetic field relaxation is determined by both the field's geometry and its topology. For relaxation processes, however, it turns out that its topology is a much more stringent constraint. As quantifier for the topology we use magnetic helicity and test whether it is a stronger condition than the linking of field lines. Further, we search for evidence of other topological invariants, which give rise to further restrictions in the field's relaxation. We find that magnetic helicity is the sole determinant in most cases. Nevertheless, we see evidence for restrictions not captured through magnetic helicity.
Theory of differential rotation and meridional circulation
Authors: Kitchatinov Leonid L. 
Published: July 2013

AbstractMeridional flow results from slight deviations from the thermal wind balance. The deviations are relatively large in the boundary layers near the top and bottom of the convection zone. Accordingly, the meridional flow attains its largest velocities at the boundaries and decreases inside the convection zone. The thickness of the boundary layers, where meridional flow is concentrated, decreases with rotation rate, so that an advection-dominated regime of dynamos is not probable in rapidly rotating stars. Angular momentum transport by convection and by the meridional flow produce differential rotation. The convective fluxes of angular momentum point radially inward in the case of slow rotation but change their direction to equatorward and parallel to the rotation axis as the rotation rate increases. The differential rotation of main-sequence dwarfs is predicted to vary mildly with rotation rate but increase strongly with stellar surface temperature. The significance of differential rotation for dynamos has the opposite tendency to increase with spectral type.
Solar differential rotation: hints to reproduce a near-surface shear layer in global simulations
Authors: Guerrero G. , Smolarkiewicz P. K. , Kosovichev A. , Mansour N. 
Published: July 2013

AbstractConvective turbulent motions in the solar interior, as well as the mean flows resulting from them, determine the evolution of the solar magnetic field. With the aim to get a better understanding of these flows we study anelastic rotating convection in a spherical shell whose stratification resembles that of the solar interior. This study is done through numerical simulations performed with the EULAG code. Due to the numerical formulation, these simulations are known as implicit large eddy simulations (ILES), since they intrinsically capture the contribution of, non-resolved, small scales at the same time maximizing the effective Reynolds number. We reproduce some previous results and find a transition between buoyancy and rotation dominated regimes which results in anti-solar or solar like rotation patterns. Even thought the rotation profiles are dominated by Taylor-Proudman columnar rotation, we are able to reproduce the tachocline and a low latitude near-surface shear layer. We find that simulations results depend on the grid resolution as a consequence of a different sub-grid scale contribution.
Development and first year of results from the Heliometer of Observatório Nacional
Authors: Andrei Alexandre H. , D'Ávila Victor A. , Neto Eugânio Reis , Penna Jucira L. , Boscardin Sérgio C. , Coletti Alissandro , Oliveira Luiz C. , Sigismondi Costantino 
Published: July 2013

AbstractRecent research on global climate changes points to three distinct sources of climate disturbance: anthropogenic; natural changes in the oceans and atmosphere; and irregularities in the solar cycles. One of the most direct ways to survey an exogenous component of the climatic variability is through the measurement of variations in the diameter and shape of the solar disk. At Observatório Nacional/MCTI, Rio de Janeiro, after several years of diameter observation using a CCD Solar Astrolabe, these measurements are now performed by a state-of-the-art Solar Heliometer. The heliometric method is one of the most successful techniques to measure small variations of angles. Its principle has been used for the latest space borne astrometric missions, aiming to milli-arcsecond precision. The success of this method relies in the fact that it minimizes the dependence of angular measurements to the thermal and mechanical stability of the instrument. However in the classic heliometer the objective is split into two halves to which is applied a linear displacement along the cut, thus still leaving room for a residual dependence with the focus, due to non-concentricity of the beams of the two images. The focus variation, as well as the effects brought by the large temperature variations during solar observations, was tackled in the Solar Heliometer by having all optical elements and their niches made on CCZ, and the telescope tube on carbon fiber, both materials of negligible thermal coefficient. Additionally, the measures are made perpendicular to the separation direction and the plate scale can be known at every time from the solar motion itself. We present the results from the first year of measurements, in special exploring the upheaval of solar activity on late 2011.
Five-element Digital Corrector Receiver for the Chinese Spectral Radioheliograph
Authors: Zhao An , Yan Yihua , Wang Wei , Chen Linjie , Zhang Jian , Liu Fei 
Published: July 2013

AbstractThe design of five-element digital receiver system is decribed. At first, we analyzed the process of data processing in the receiver system. Then we wrote programs to implement the FIR parallel filter and showed its simulation results. Finally the testing result of the correlation receiver system is demonstrated.
Observations of a geomagnetic SI+ – SI− pair and associated solar wind fluctuations
Authors: Bisoi Susanta Kumar , Janardhan P. 
Published: July 2013

AbstractWe report a pair of oppositely directed sudden impulses (SI), in the geomagnetic field (ΔX), at ground stations, called SI+ – SI− pairs, that occurred between 1835 UT and 2300 UT on 23 April 1998. The SI+ – SI− pair, was well correlated with corresponding variations in the solar wind density, while solar wind velocity and the southward component of the interplanetary magnetic field (Bz) did not show any correspondence. This event had no source on the visible solar disk but was associated with a rear-side fast partial halo coronal mass ejection (CME) and an optically occulted M1.4 class solar flare behind the west limb. This event was unique in that one could clearly identify variations in ΔX at ground stations with solar wind parameters.
Frequency and time properties of decimeter narrowband spikes in solar flares
Authors: Wang Shujuan 
Published: July 2013

AbstractIn this paper, we focus to study the frequency and time properties of a group of spikes recorded by the 1.08-2.04 GHz spectrometer of NAOC on 27 October 2003. At the first we calculate the mean and minimum bandwidth of the spikes. We apply two different methods based on the wavelet analysis according to Messmer & Benz (2000). The first method determines the dominant spike bandwidth scale based on their scalegram, and the second method is a feature detection algorithm in the time-frequency plane. Secondly the time profile of each single spike was fitted and analyzed. In particular, we determined the e-folding rise and decay times corresponding to the ascending and decaying parts of the time profile, respectively. Several important correlations were studied and compared with the results in earlier literature, i.e. those between duration and frequency, e-folding rise time and decay time, e-folding decay time and duration, and e-folding decay time and peak flux. Finally some parameters of source region were estimated and the possible decaying mechanism was discussed.
Study of ribbon separation and magnetic reconnection rates
Authors: Xie Wenbin , Zhang Hongqi , Lin Jun , Wang Haimin 
Published: July 2013

AbstractWe study the correlation between the speed of two-ribbon separation and the magnetic flux density during the 2001 April 10 solar flare. A weak negative correlation is found between the ribbon separation speed (Vr) and the longitudinal magnetic flux density (Bz). In addition, we estimate the magnetic reconnection rate (Erec). Along the flare ribbons, Erec fluctuates in the small range except near the HXR source. The localized enhancement of the reconnection rate corresponds to the position of the HXR source.
BET inhibition as a single or combined therapeutic approach in primary paediatric B-precursor acute lymphoblastic leukaemia
Authors: Da Costa D , Agathanggelou A , Perry T , Weston V , Petermann E , Zlatanou A , Oldreive C , Wei W , Stewart G , Longman J , Smith E , Kearns P , Knapp S , Stankovic T 
Published: July 2013

AbstractPaediatric B-precursor ALL is a highly curable disease, however, treatment resistance in some patients and the long-term toxic effects of current therapies pose the need for more targeted therapeutic approaches. We addressed the cytotoxic effect of JQ1, a highly selective inhibitor against the transcriptional regulators, bromodomain and extra-terminal (BET) family of proteins, in paediatric ALL. We showed a potent in vitro cytotoxic response of a panel of primary ALL to JQ1, independent of their prognostic features but dependent on high MYC expression and coupled with transcriptional downregulation of multiple pro-survival pathways. In agreement with earlier studies, JQ1 induced cell cycle arrest. Here we show that BET inhibition also reduced c-Myc protein stability and suppressed progression of DNA replication forks in ALL cells. Consistent with c-Myc depletion and downregulation of pro-survival pathways JQ1 sensitised primary ALL samples to the classic ALL therapeutic agent dexamethasone. Finally, we demonstrated that JQ1 reduces ALL growth in ALL xenograft models, both as a single agent and in combination with dexamethasone. We conclude that targeting BET proteins should be considered as a new therapeutic strategy for the treatment of paediatric ALL and particularly those cases that exhibit suboptimal responses to standard treatment.
Comparative metatranscriptomics reveals kingdom level changes in the rhizosphere microbiome of plants
Authors: Turner Thomas R , Ramakrishnan Karunakaran , Walshaw John , Heavens Darren , Alston Mark , Swarbreck David , Osbourn Anne , Grant Alastair , Poole Philip S 
Published: July 2013

Abstract
Plant–microbe interactions in the rhizosphere have important roles in biogeochemical cycling, and maintenance of plant health and productivity, yet remain poorly understood. Using RNA-based metatranscriptomics, the global active microbiomes were analysed in soil and rhizospheres of wheat, oat, pea and an oat mutant (sad1) deficient in production of anti-fungal avenacins. Rhizosphere microbiomes differed from bulk soil and between plant species. Pea (a legume) had a much stronger effect on the rhizosphere than wheat and oat (cereals), resulting in a dramatically different rhizosphere community. The relative abundance of eukaryotes in the oat and pea rhizospheres was more than fivefold higher than in the wheat rhizosphere or bulk soil. Nematodes and bacterivorous protozoa were enriched in all rhizospheres, whereas the pea rhizosphere was highly enriched for fungi. Metabolic capabilities for rhizosphere colonisation were selected, including cellulose degradation (cereals), H2 oxidation (pea) and methylotrophy (all plants). Avenacins had little effect on the prokaryotic community of oat, but the eukaryotic community was strongly altered in the sad1 mutant, suggesting that avenacins have a broader role than protecting from fungal pathogens. Profiling microbial communities with metatranscriptomics allows comparison of relative abundance, from multiple samples, across all domains of life, without polymerase chain reaction bias. This revealed profound differences in the rhizosphere microbiome, particularly at the kingdom level between plants.
Numerical study on a 0.4 THz second harmonic gyrotron with high power
Authors: Chaojun Lei , Sheng Yu , Hongfu Li , Yinghui Liu , Xinjian Niu , Qixiang Zhao 
Published: July 2013

Terahertz and sub-terahertz science and technology are promising topics today. However, it is difficult to obtain high power source of terahertz wave. In this paper, the mode competition and beam-wave interaction in a gradually tapered cavity are studied to achieve high efficiency of a 0.4THz second harmonic gyrotron in practice. In order to attain high power and stable radiation, the TE32,5 mode is selected as the operating mode of the desired gyrotron to realize single mode oscillation. The issues of studying on the high-order mode gyrotrons are solved effectively by transforming the generalized telegraphist's equations. The efficiency and output power of the gyrotron under different conditions have been calculated by the code, which is based on the transformed equations. Consequently, the results show that single mode second harmonic radiation with power of over 150 kW at frequency of 0.4 THz could be achieved.
Transnational Trade Union Action in Europe
Authors: Larsson Bengt 
Published: July 2013

ABSTRACT
Research on European trade unionism has discussed whether the tendency towards ‘union diplomacy’ has meant that that unions are largely disinterested in mobilizing members and pursue contentious action at the European level. Other studies have identified activities that suggest an Europeanization of political mobilization, in demonstrations and strikes and in cooperation with NGOs and social movements. The present paper analyzes attitudes towards transnational action among trade unions in Europe, as well as the degree to which national unions actually partake in more and less contentious action. The study, which is based on a survey to trade unions in Europe carried out in 2010–11 (n 250), focuses particularly on the production of joint statements and petitions, demonstrations and boycotts, and strikes. The aim was to identify the similarities and differences between industrial relations regimes and sectors in Europe and the analyses have revealed that there are in fact significant differences. Trade unions in the continental social partnership regime and the southern polarized/state centered regime tend to approve of and partake in European demonstrations and boycotts to a higher degree than unions in the other regimes, while the Nordic unions in the organized corporatist regime tend to be more skeptical and also participate to a lower degree. In addition, unions in services and organizing professionals tend to partake and approve of such action to a lower degree than unions in other sectors and national peak level unions.
Brainwave entrainment for better sleep and post‐sleep state of young elite soccer players – A pilot study
Authors: Abeln Vera , Kleinert Jens , Strüder Heiko K. , Schneider Stefan 
Published: July 2013

AbstractThe effect of sleep deprivation on psychophysical performance and well‐being is comprehensively investigated. Research investigating the effect of improved sleep is rare. Just as little exists about attempts to support athletic mental state and performance by improving sleep quality. This study aims to investigate whether sleep quality of top athletes can be improved by auditory brainwave entrainment and whether this leads to enhancements of post‐sleep psychophysical states. In a pilot study, 15 young elite soccer players were stimulated for eight weeks during sleep with binaural beats around 2–8 Hz. Once a week after wake‐up, participants completed three different questionnaires: a sleep diary, an adjective list for psychophysical and motivational state, and a self‐assessment questionnaire for sleep and awakening quality. Fifteen sport students executed the same protocol sleeping on the same pillow, but without stimulation. Subjective ratings of sleep and awakening quality, sleepiness and motivational state were significantly improved only in the intervention group, but did not impact their perceived physical state. In summary, eight weeks of auditory stimulation with binaural beats improved perceived sleep quality and the post‐sleep state of athletes, whereas the effect on physical level is assumed to occur in a time‐delayed fashion. It seems to be worthwhile – to further elaborate long‐time effects and consequences on physical and mental performance.
Decision-contextual and individual influences on scarcity effects
Authors: Ku Hsuan-Hsuan , Kuo Chien-Chih , Yang Yi-Ting , Chung Tzu-Shao 
Published: July 2013

Purpose
– This study aims to examine the relative effectiveness of demand-related and supply-related explanations of the scarcity of a product, and specifically the extent to which decision context and individual factors moderate purchase intention in response to those explanations.

Design/methodology/approach
– The first of two formal experiments examines the effects of the two kinds of scarcity on participants
'
purchase intentions with respect to utilitarian and hedonic product types. The second tests for self-monitoring differences in participants
'
relative susceptibility to scenarios characterizing scarcity as either demand-generated or supply-generated, when their decisions are either private or subject to third-party scrutiny.

Findings
– Experiment 1 shows that participants shopping for a utilitarian product are more inclined to respond positively to what they understand to be demand-generated scarcity, and less inclined to do so if the scarcity was attributed to limited supply; whereas the converse holds true for a hedonic product. Experiment 2 shows that for high self-monitors, increased purchase intention was the outcome of matching the alleged reason for scarcity to the demands of the decision context; low self-monitors were ready to consider demand-scarce products regardless of whether they knew that their consumption decisions would be subject to third-party scrutiny or private.

Originality/value
– The paper identifies contextual and individual factors that explain and predict the extent to which one type of scarcity appeal may be more effective than another in influencing consumers
'
purchasing decisions.