Method of measuring cross-flow vortices by use of an array of hot-film sensors

The invention is a method for measuring the wavelength of cross-flow vortices of air flow having streamlines of flow traveling across a swept airfoil. The method comprises providing a plurality of hot-film sensors. Each hot-film sensor provides a signal which can be processed, and each hot-film sensor is spaced in a straight-line array such that the distance between successive hot-film sensors is less than the wavelength of the cross-flow vortices being measured. The method further comprises determining the direction of travel of the streamlines across the airfoil and positioning the straight-line array of hot film sensors perpendicular to the direction of travel of the streamlines, such that each sensor has a spanwise location. The method further comprises processing the signals provided by the sensors to provide root-mean-square values for each signal, plotting each root-mean-square value as a function of its spanwise location, and determining the wavelength of the cross-flow vortices by noting the distance between two maxima or two minima of root-mean-square values

What sets the magnetic field strength and cycle period in solar-type stars?

Two fundamental properties of stellar magnetic fields have been determined by observations for solar-like stars with different Rossby numbers (Ro), namely, the magnetic field strength and the magnetic cycle period. The field strength exhibits two regimes: 1) for fast rotation it is independent of Ro, 2) for slow rotation it decays with Ro following a power law. For the magnetic cycle period two regimes of activity, the active and inactive branches, also have been identified. For both of them, the longer the rotation period, the longer the activity cycle. Using global dynamo simulations of solar like stars with Rossby numbers between ~0.4 and ~2, this paper explores the relevance of rotational shear layers in determining these observational properties. Our results, consistent with non-linear alpha^2-Omega dynamos, show that the total magnetic field strength is independent of the rotation period. Yet at surface levels, the origin of the magnetic field is determined by Ro. While for Ro<1 it is generated in the convection zone, for Ro>1 strong toroidal fields are generated at the tachocline and rapidly emerge towards the surface. In agreement with the observations, the magnetic cycle period increases with the rotational period. However, a bifurcation is observed for Ro~1, separating a regime where oscillatory dynamos operate mainly in the convection zone, from the regime where the tachocline has a predominant role. In the latter the cycles are believed to result from the periodic energy exchange between the dynamo and the magneto-shear instabilities developing in the tachocline and the radiative interior.Comment: 43 pages, 14 figures, accepted for publication in The Astrophysical Journa

Spatial interactions in agent-based modeling

Agent Based Modeling (ABM) has become a widespread approach to model complex interactions. In this chapter after briefly summarizing some features of ABM the different approaches in modeling spatial interactions are discussed. It is stressed that agents can interact either indirectly through a shared environment and/or directly with each other. In such an approach, higher-order variables such as commodity prices, population dynamics or even institutions, are not exogenously specified but instead are seen as the results of interactions. It is highlighted in the chapter that the understanding of patterns emerging from such spatial interaction between agents is a key problem as much as their description through analytical or simulation means. The chapter reviews different approaches for modeling agents' behavior, taking into account either explicit spatial (lattice based) structures or networks. Some emphasis is placed on recent ABM as applied to the description of the dynamics of the geographical distribution of economic activities, - out of equilibrium. The Eurace@Unibi Model, an agent-based macroeconomic model with spatial structure, is used to illustrate the potential of such an approach for spatial policy analysis.Comment: 26 pages, 5 figures, 105 references; a chapter prepared for the book "Complexity and Geographical Economics - Topics and Tools", P. Commendatore, S.S. Kayam and I. Kubin, Eds. (Springer, in press, 2014

Magnetic Field Effects on the Structure and Evolution of Overdense Radiatively Cooling Jets

We investigate the effect of magnetic fields on the propagation dynamics and morphology of overdense, radiatively cooling, supermagnetosonic jets, with the help of fully three-dimensional SPMHD simulations. Evaluated for a set of parameters which are mainly suitable for protostellar jets (with density ratios between the jet and the ambient medium 3-10, and ambient Mach number ~ 24), these simulations are also compared with baseline non-magnetic and adiabatic calculations. We find that, after amplification by compression and re-orientation in nonparallel shocks at the working surface, the magnetic field that is carried backward with the shocked gas into the cocoon improves the jet collimation relative to the purely hydrodynamic (HD) systems. Low-amplitude, approximately equally spaced internal shocks (which are absent in the HD systems) are produced by MHD K-H reflection pinch modes. The longitudinal field geometry also excites non-axisymmetric helical modes which cause some beam wiggling. The strength and amount of these modes are, however, reduced (by ~ twice) in the presence of radiative cooling relative to the adiabatic cases. Besides, a large density ratio between the jet and the ambient medium also reduces, in general, the number of the internal shocks. As a consequence, the weakness of the induced internal shocks makes it doubtful that the magnetic pinches could produce by themselves the bright knots observed in the overdense, radiatively cooling protostellar jets.Comment: To appear in ApJ; 36 pages + 16 (gif) figures. PostScript files of figures are available at http://www.iagusp.usp.br/preprints/preprint.htm

Toward a Multi-Dimensional Model of Adolescent Romantic Parasocial Attachment

Relationships with media figures—referred to as parasocial relationships—provide a means for adolescents to explore and define their romantic and sexual identities (Boon & Lomore, 2001; Engle & Kasser, 2005; Karniol, 2001). However, more often than not, adolescents’ romantic attachments to media figures are ignored or dismissed as frivolous in the scholarly literature on youth development (Caughey, 1984; Jenkins, 1992; Willis, 1972). In this paper, we introduce a theoretical model of adolescent romantic parasocial attachment (ARPA) designed to facilitate a comprehensive, developmentally-based line of research that improves our understanding of the ways adolescents experience parasocial romance and the influence their experiences may have on their lives. Implications for the study of adolescent romantic development and future research directions are proposed

Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

We demonstrate quantitative magnetic field mapping with nanoscale resolution, by applying a lock-in technique on the electron spin resonance frequency of a single nitrogen-vacancy defect placed at the apex of an atomic force microscope tip. In addition, we report an all-optical magnetic imaging technique which is sensitive to large off-axis magnetic fields, thus extending the operation range of diamond-based magnetometry. Both techniques are illustrated by using a magnetic hard disk as a test sample. Owing to the non-perturbing and quantitative nature of the magnetic probe, this work should open up numerous perspectives in nanomagnetism and spintronics

Zircon dissolution in a ductile shear zone, Monte Rosa granite gneiss, northern Italy

The sizes, distributions and shapes of zircon grains within variably deformed granite gneiss from the western Alps have been studied. Zircon shows numerous indicators of a metamorphic response in both the host gneiss and a 5 cm wide continuous ductile shear zone, within which the zircon grain sizes range from &#60;1 µm to &#62;50 µm. However, the very fine grain sizes are virtually absent from grain boundaries. Within this zone, zircons consistently have more rounded and embayed margins, which are interpreted as evidence of dissolution in response to fluid influx during shearing. Zircons are preferentially located near metamorphic muscovite in both the host gneiss and the shear zone and tend to show the poorest crystal shape, indicating that fluids linked to the formation and presence of muscovite may enhance both the crystallization of zircon and its subsequent dissolution. Larger zircon crystals typically show a brittle response to deformation when adjacent to phyllosilicates, with fractures consistently perpendicular to the (001) mica cleavage. The variety of metamorphic behaviour observed for zircon indicates that it may be highly reactive in sub-solidus mid-crustal metamorphic environments

The impact of socioeconomic status on arthritis and osteoporosis

Background: Low socioeconomic status has been shown to be associated with both osteoarthri s and rheumatoid arthri s, impac ng on outcomes and even the development of arthri s. However the associa on with osteoporosis has been less clear. The reasons for the associa on may be linked to socioeconomic status through educa onal aspects, income, employment type and even area of residence. Purpose: The purpose of this study was use a monthly surveillance and monitoring system to examine the prevalence of self-reported osteoarthri s, rheumatoid arthri  s and osteoporosis over  me and the associa  on with measures of socioeconomic status