bluuebunny/crossref_metadata_2025_split huggingface dataset:
Externalization of policy advice: Theory, methodology and evidence
Authors: Veselý Arnošt 
Published: July 2013

AbstractThis paper examines to what extent advisory activities previously performed inside the government have been relocated to places outside of government. Although this process, labelled as externalization of policy advice, is widely taken as a universal trend, here it is shown that empirical findings suggest a more complicated picture. The level of externalization differs across policy domains, countries and over time. There are also different meanings of externalization and it has both quantitative and qualitative dimensions. In this article it is argued that the provision of policy advice can be conceptualized in terms of two competing processes: externalization and filling-in. The strength of these processes depends upon a wide range of factors. An overview of the empirical findings on externalization is provided and the factors assumed to be conducive to externalization are outlined. The article concludes with implications for further research, arguing that empirical research should be more theory-driven and enhanced by the inclusion of other research designs and methods.
Interfacial instability of coupled-rotating inviscid fluids
Authors: Ghantous Malek , Bye John A. T. 
Published: July 2013

AbstractWe consider the three-dimensional, cylindrical equivalent to the problem of instability between two inviscid fluids due to a velocity shear between them, known as Kelvin–Helmholtz instability. We begin by developing the solution to the linearized equations for a rotating fluid. While this solution is not in itself new, we carry the analysis further than previous treatments by including non-zero modes and considering the effect of the surface tension, particularly on the dispersion relation. We then consider a system of two fluids rotating at different rates and derive its dispersion relation, which is rather more complicated than that for a single rotating fluid. While a general analytic solution is unattainable, by investigating some special cases we show that the fundamental mode is always stable, and that Kelvin–Helmholtz instability also exists for the system. We compare our results with experiments and conclude by suggesting some hypothetical links between the theory and nature.
Unsteady separation leading to secondary and tertiary vortex dynamics: the sub-- and sub--phenomena
Authors: Kalita Jiten C. , Sen Shuvam 
Published: July 2013

AbstractStudies on the$\alpha $- and$\beta $-phenomena, terms coined by Bouard & Coutanceau (J. Fluid Mech., vol. 101, 1980, pp. 583–607) for the flow past an impulsively started circular cylinder, have been confined only to the very early stages of the flow. In this paper, besides making a comprehensive in-depth analysis of these phenomena for a much longer period of time, we report the existence of some tertiary vortex phenomena for the first time, which we term the sub-$\alpha $- and sub-$\beta $-phenomena. The mechanism of unsteady flow separation at high Reynolds numbers for the flow past a circular cylinder developed in the last two decades has been used to understand these flow phenomena. The flow is computed using a recently developed compact finite difference method for the biharmonic form of the two-dimensional Navier–Stokes equations for the range of Reynolds number$500\leq \mathit{Re}\leq 10\hspace{0.167em} 000$. We specifically choose$\mathit{Re}= 5000$to describe the interplay among the primary, secondary and tertiary vortices leading to these interesting vortex dynamics. We also report a$\beta $-like phenomenon which is very similar to the$\beta $-phenomenon, but slightly differs in details. We offer a new perception of the$\alpha $-phenomenon by defining its existence in a strong and weak sense along with a clearer characterization of the$\beta $-phenomenon. Apart from numerical computation, a detailed theoretical characterization using topological aspects of the boundary layer separation leading to the secondary and tertiary vortex phenomena has also been carried out. We compare our numerical results with established experimental and numerical results wherever available and an excellent match with the experimental results is obtained in all cases.
Laminarization mechanisms and extreme-amplitude states in rapidly rotating plane channel flow
Authors: Wallin Stefan , Grundestam Olof , Johansson Arne V. 
Published: July 2013

AbstractFully developed plane channel flow rotating in the spanwise direction has been studied analytically and numerically. Linear stability analysis reveals that all cross-flow modes are stable for supercritical rotation numbers, $Ro\gt R{o}_{c} $, where $R{o}_{c} $ will approach 3 from below for increasing Reynolds number. Plane Tollmien–Schlichting (TS) waves are independent of rotation and always linearly unstable for supercritical Reynolds numbers. Direct numerical simulation (DNS) of the laminarization process reveals that the turbulence is damped when $Ro$ approaches $R{o}_{c} $. Hence, the laminarization is dominated by linear mechanisms. The flow becomes periodic for supercritical Reynolds numbers and rotation rates, i.e. when $Ro\gt R{o}_{c} $ and $Re\gt R{e}_{c} $. At such rotation rates, all oblique (cross-flow) modes are damped and when the disturbance amplitude becomes small enough, the TS modes start to grow exponentially. Secondary instabilities are initially blocked by the rotation since all cross-flow modes are linearly stable and the breakdown to turbulence will be strongly delayed. Hence, the TS waves will reach extremely high amplitudes, much higher than for typical turbulent fluctuations. Eventually, the extreme-amplitude state with TS-like waves will break down to turbulence and the flow will laminarize due to the influence of the rapid rotation, thus completing the cycle that will then be repeated. This flow is strongly dominated by linear mechanisms, which is remarkable considering the extremely high amplitudes involved in the processes of laminarization of the turbulence at $Ro\geq R{o}_{c} $ and the growth of the unstable TS waves.
Grid turbulence in dilute polymer solutions: PEO in water
Authors: Vonlanthen Richard , Monkewitz Peter A. 
Published: July 2013

AbstractGrid turbulence of polyethylene oxide (PEO) solutions (Polyox WSR-301 in${\mathrm{H} }_{2} \mathrm{O} $) has been investigated experimentally for three concentrations of 25, 50 and 100 weight ppm, at a turbulence Reynolds number based on a Taylor microscale of${\mathit{Re}}_{\lambda } \approx 100$. For the first time, time sequences of turbulence spectra have been acquired at a rate of 0.005 Hz to reveal the spectral evolution due to mechanical degradation of the polymers. In contrast to spectra averaged over the entire degradation process, the sequence of spectra reveals a clear but time-dependent Lumley scale at which the energy spectrum changes abruptly from the Kolmogorov${\kappa }^{- 5/ 3} $inertial range to a${\kappa }^{- 3} $elastic range, in which the rate of strain is maintained constant by the polymers. The scaling of the initial Lumley length with Kolmogorov dissipation rate${\epsilon }_{0} $and molecular weight is determined, and a cascade model for the temporal decrease of molecular weight, i.e. for the breaking of polymer chains is presented. Finally, a heuristic model spectrum is developed which covers the cases of both maximum and partial turbulence reduction by polymers.
Two-scale dynamics of flow past a partial cross-stream array of tidal turbines
Authors: Nishino Takafumi , Willden Richard H. J. 
Published: July 2013

AbstractThe characteristics of flow past a partial cross-stream array of (idealized) tidal turbines are investigated both analytically and computationally to understand the mechanisms that determine the limiting performance of partial tidal fences. A two-scale analytical partial tidal fence model reported earlier is further extended by better accounting for the effect of array-scale flow expansion on device-scale dynamics, so that the new model is applicable to short fences (consisting of a small number of devices) as well as to long fences. The new model explains theoretically general trends of the limiting performance of partial tidal fences. The new model is then compared to three-dimensional Reynolds-averaged Navier–Stokes (RANS) computations of flow past an array of various numbers (up to 40) of actuator disks. On the whole, the analytical model agrees well with the RANS computations, suggesting that the two-scale dynamics described in the analytical model predominantly determines the fence performance in the RANS computations as well. The comparison also suggests that the limiting performance of short partial fences depends on how much of device far-wake mixing takes place within the array near-wake region. This factor, however, depends on the structures of the wake and therefore on the type/design of devices to be arrayed.
Split energy–helicity cascades in three-dimensional homogeneous and isotropic turbulence
Authors: Biferale L. , Musacchio S. , Toschi F. 
Published: July 2013

AbstractWe investigate the transfer properties of energy and helicity fluctuations in fully developed homogeneous and isotropic turbulence by changing the nature of the nonlinear Navier–Stokes terms. We perform a surgery of all possible interactions, by keeping only those triads that have sign-definite helicity content. In order to do this, we apply an exact decomposition of the velocity field in a helical Fourier basis, as first proposed by Constantin & Majda (Commun. Math. Phys, vol. 115, 1988, p. 435) and exploited in great detail by Waleffe (Phys. Fluids A, vol. 4, 1992, p. 350), and we evolve the Navier–Stokes dynamics keeping only those velocity components carrying a well-defined (positive or negative) helicity. The resulting dynamics preserves translational and rotational symmetries but not mirror invariance. We give clear evidence that this three-dimensional homogeneous and isotropic chiral turbulence is characterized by a stationary inverse energy cascade with a spectrum ${E}_{back} (k)\sim {k}^{- 5/ 3} $ and by a direct helicity cascade with a spectrum ${E}_{forw} (k)\sim {k}^{- 7/ 3} $. Our results are important to highlight the dynamics and statistics of those subsets of all possible Navier–Stokes interactions responsible for reversal events in the energy-flux properties, and demonstrate that the presence of an inverse energy cascade is not necessarily connected to a two-dimensionalization of the flow. We further comment on the possible relevance of such findings to flows of geophysical interest under rotations and in thin layers. Finally we propose other innovative numerical experiments that can be achieved by using a similar decimation of degrees of freedom.
A variable neighborhood search method for a two-mode blockmodeling problem in social network analysis
Authors: BRUSCO MICHAEL , DOREIAN PATRICK , LLOYD PAULETTE , STEINLEY DOUGLAS 
Published: July 2013

AbstractThis paper presents a variable neighborhood search (VNS) algorithm that is specially designed for the blockmodeling of two-mode binary network matrices in accordance with structural equivalence. Computational results for 768 synthetic test networks revealed that the VNS heuristic outperformed a relocation heuristic (RH) and a tabu search (TS) method for the same problem. Next, the three heuristics were applied to two-mode network data pertaining to the votes of member countries on resolutions in the United Nations General Assembly. A comparative analysis revealed that the VNS heuristic often provided slightly better criterion function values than RH and TS, and that these small differences in criterion function values could sometimes be associated with substantial differences in the actual partitions obtained. Overall, the results suggest that the VNS heuristic is a promising approach for blockmodeling of two-mode binary networks. Recommendations for extensions to stochastic blockmodeling applications are provided.
REGULAR CONGRUENCES ON AN IDEMPOTENT-REGULAR-SURJECTIVE SEMIGROUP
Authors: GIGOŃ ROMAN S. 
Published: July 2013

AbstractA semigroup $S$ is called idempotent-surjective (respectively, regular-surjective) if whenever $\rho $ is a congruence on $S$ and $a\rho $ is idempotent (respectively, regular) in $S/ \rho $, then there is $e\in {E}_{S} \cap a\rho $ (respectively, $r\in \mathrm{Reg} (S)\cap a\rho $), where ${E}_{S} $ (respectively, $\mathrm{Reg} (S)$) denotes the set of all idempotents (respectively, regular elements) of $S$. Moreover, a semigroup $S$ is said to be idempotent-regular-surjective if it is both idempotent-surjective and regular-surjective. We show that any regular congruence on an idempotent-regular-surjective (respectively, regular-surjective) semigroup is uniquely determined by its kernel and trace (respectively, the set of equivalence classes containing idempotents). Finally, we prove that all structurally regular semigroups are idempotent-regular-surjective.
EMERGING CHRISTIAN MEDIA IN EGYPT: CLERICAL AUTHORITY AND THE VISUALIZATION OF WOMEN IN COPTIC VIDEO FILMS
Authors: Armanios Febe , Amstutz Andrew 
Published: July 2013

AbstractThis article examines the depiction of women and gender within Coptic Orthodox video films or “hagiopics” produced between 1987 and 2010. As part of a recent religious renewal, hagiopics have expanded, altered, and reinvented traditional stories of saints and pious figures and have also generated, within this traditionally patriarchal setting, a wider space for the articulation of female voices. While their inclusion can be seen as potentially empowering for women, this paper suggests that during Pope Shenouda III's reign (1971–2012), the films became a powerful vehicle for broadcasting the church's conservative teachings on female power and authority, marriage and marital dissolution, spousal abuse, and femininity. By highlighting an array of exemplary female characters, hagiopics capture women's role as custodians of a distinctive Coptic ethos and of family and communal cohesiveness. The films’ emphasis on women's physical modesty, submissiveness, and obedience to male figureheads also hints at the modern church's anxieties about women's increasing autonomy in choosing marriage partners and their growing demands for more equal treatment within the church.
Nonlinear interaction of obliquely propagating Alfvén waves and kinetic Alfvén waves in solar wind plasmas
Authors: YADAV NITIN , SHARMA R. P. 
Published: July 2013

AbstractThe nonlinear interaction of kinetic Alfvén waves (KAWs) with other possible plasma modes is considered to be responsible for the observed solar wind turbulent spectrum. In the present paper, a new channel of interaction between a KAW and an obliquely propagating Alfvén wave (AW) has been proposed. The governing dynamical equations are derived and the nonlinear interaction between the two wave modes KAW and AW is studied. The growth rate of modulational instability has been calculated. The nonlinear evolution of KAW filamentation and turbulent spectra has also been discussed. In the inertial range, energy cascade follows nearly Kolmogorov scaling, and after inertial range it follows −2.5 scaling in dispersive range. The obtained results indicate that the proposed mechanism may be responsible for transferring the energy from smaller wavenumbers to larger wavenumbers in the solar wind plasmas. The relevance of the present study with recent Cluster spacecraft observations has also been pointed out.
Harmonic generation by the propagation of two-colour laser beams in an underdense plasma
Authors: JHA PALLAVI , VERMA NIRMAL KUMAR , SAROCH AKANKSHA 
Published: July 2013

AbstractAn analytical theory is developed for studying the phenomenon of generation of efficient odd and even high harmonics by the propagation of two-colour linearly polarized laser beams in a homogeneous underdense plasma. The wave equation governing the evolution of the amplitude of various harmonics driven by the current density at corresponding frequencies is set up. The ratio of the fundamental frequencies of the two laser beams is considered to be an arbitrary integer. A numerical evaluation of amplitudes of the third, fourth and fifth harmonics has been presented. It is seen that the third harmonic amplitude generated by the two-colour system is enhanced in comparison to that obtained by a single laser beam. The detuning distance for the former is also increased in comparison to the latter case.
Administrator-scholars and the Writing of History in Early British India: A review article
Authors: LEES JAMES 
Published: July 2013

AbstractThe histories of Asian peoples penned by British East India Company officials during the early years of colonial rule—rightly—have long been considered to be doubtful source material within the historiography of South Asia. Their credibility was suspect well before the middle of the twentieth century, when Bernard Cohn's work began to present the British colonial state as one that relentlessly sought to categorize Indian society, and to use the distorted information thus gained to impose its government.However, the histories of these administrator-scholars still retain value—not as accurate studies of their subjects, perhaps, but as barometers of the times in which they were written and also in the unexpected ways in which some continue to resonate in the present. To illustrate that point, this paper will review three recent monographs which deal with the writings and historical legacies of some of the Company's most prominent early nineteenth-century administrator-scholars. These are: Jason Freitag'sServing Empire, Serving Nation: James Tod and the Rajputs of Rajasthan; Jack Harrington'sSir John Malcolm and the Creation of British India; and Rama Mantena's work centred around the antiquarian pursuits of Colin Mackenzie,The Origins of Modern Historiography in India: Antiquarianism and Philology, 1780–1880.1
Critical population status of the jaguar Panthera onca in the Argentine Chaco: camera-trap surveys suggest recent collapse and imminent regional extinction
Authors: Quiroga Verónica Andrea , Boaglio Gabriel Iván , Noss Andrew Jay , Di Bitetti Mario Santiago 
Published: July 2013

AbstractThe population of jaguars Panthera onca in the semi-arid Chaco Province is the least well-known in Argentina. Its status in the region is described only from interviews that confirmed its presence until 2003. To update information on the distribution and population density of this species we undertook three camera-trap surveys, combined with searches for sign, at sites across latitudinal and protection gradients, and 156 interviews with local inhabitants across three larger areas. The camera-trap sites were located in areas with the highest density of records in the Argentine Chaco: Copo National Park (1,204 trap days, 24 stations, 344 km of transects), Aborigen Reserve (1,993 trap days, 30 stations, 251 km of transects) and El Cantor (2,129 trap days, 35 stations, 297 km of transects). We did not obtain any photographs of jaguars. We recorded very few jaguar tracks, and only in the Aborigen Reserve (n = 3) and El Cantor (n = 1). The map of distribution points confirmed through interviews suggests that the jaguar range has not changed significantly in the past 10 years; however, the camera-trap and sign surveys suggest that densities are extremely low. Before our study the Chaco population was thought to be the largest in Argentina. This perception was incorrect: the Chaco jaguar population is the most threatened in the country. Systematic, intensive studies are essential to provide the necessary information for decision-making for the management and conservation of threatened species.
On the Structure and Life Histories of British Fresh-water Furcocercariae
Authors: Harper W. F. 
Published: July 2013

Three species of furcocercariae are described. By means of direct animal experiment with secondary, intermediate and final hosts I have shown that one species develops into Tetracotyle typica Dies., the larva of Strigea tarda Steenstrup, and a connected detailed account of this life cycle is here given. Of the two other species, both of which are new, I have been able to trace the development of one into Tetracotyle n.sp. in Planorbis crista L., and P. albus Müll. Feeding experiments with this new Tetracotyle using ducklings as final hosts failed, however, to produce the corresponding adult.Effect of the parasite on the host. The usual results of helminth infection of this nature are observable, namely, marked disruption of liver tissue and in many cases complete parasitic castration of the molluscs infected.Double infection. In the course of my investigations on larval Trematodes I have met with one example of double infection with sporocysts, viz. Cercaria F.1 and F.2, within one and the same individual of Planorbis albus Müll. This condition was found only on one occasion, Cercaria F.1 being in predominance. Instances of double infection have been recorded by Faust (1971) and Sewell (1922), and from this country by Hesse (1923) and Brown (1926). The condition, however does not appear to be a common one.
Thinking through drawing
Authors: Magnani Lorenzo 
Published: July 2013

AbstractThe concept ofmanipulative abductionis devoted to capture the role of action in many interesting cognitive situations: action provides otherwise unavailable information that enables the agent to solve problems by starting and performing a suitable abductive process of generation or selection of hypotheses. We observe that many external things, usually inert from an epistemological point of view, can be transformed intoepistemic mediators. I will present some details derived from the history of the discovery of the non-Euclidean geometries that illustrate the relationships between strategies for anomaly resolution and visual thinking. Geometrical diagrams are external representations that play both amirrorrole (to externalize rough mental models) and anunveilingrole (as gateways to imaginary entities). I describe them as epistemic mediators able to perform various explanatory, non-explanatory, and instrumental abductive tasks (discovery of new properties or new propositions/hypotheses, provision of suitable sequences of models as able to convincingly verifying theorems, etc.). I am also convinced that they can be exploited and studied in everyday non-mathematical applications also to the aim of promoting new trends in artificial intelligence modeling of various aspects of hypothetical reasoning: finding routes, road signs, buildings maps, for example, in connection with various zooming effects of spatial reasoning. I also think that the cognitive activities of optical, mirror, and unveiling diagrams can be studied in other areas of manipulative and model-based reasoning, such as the ones involving creative, analogical, and spatial inferences, both in science and everyday situations so that this can extend the epistemological, computational, and the psychological theory.