Numerical simulations of multiple scattering of the f−f-mode by flux tubes

We use numerial simulations to study the absorption and phase shift of surface-gravity waves caused by groups of magnetic flux tubes. The dependence of the scattering coefficients with the distance between the tubes and their positions is analyzed for several cases with two or three flux tubes embedded in a quiet Sun atmosphere. The results are compared with those obtained neglecting completely or partially multiple scattering effects. We show that multiple scattering has a significant impact on the absorption measurements and tends to reduce the phase shift. We also consider more general cases of ensembles of randomly distributed flux tubes, and we have evaluated the effects on the scattering measurements of changing the number of tubes included in the bundle and the average distance between flux tubes. We find that for the longest wavelength incoming waves multiple scattering enhances the absorption, and its efficiency increases with the number of flux tubes and the reduction of the distance between them.Comment: Accepted for publication in The Astrophysical Journa

Evaluation of the capability of local helioseismology to discern between monolithic and spaghetti sunspot models

The helioseismic properties of the wave scattering generated by monolithic and spaghetti sunspots are analyzed by means of numerical simulations. In these computations, an incident f or p1 mode travels through the sunspot model, which produces absorption and phase shift of the waves. The scattering is studied by inspecting the wavefield, computing travel-time shifts, and performing Fourier-Hankel analysis. The comparison between the results obtained for both sunspot models reveals that the differences in the absorption coefficient can be detected above noise level. The spaghetti model produces an steep increase of the phase shift with the degree of the mode at short wavelengths, while mode-mixing is more efficient for the monolithic model. These results provide a clue for what to look for in solar observations to discern the constitution of sunspots between the proposed monolithic and spaghetti models.Comment: Accepted for publication in The Astrophysical Journa

European Employment and Labour Market Policy

European policy strategy has shifted from maintaining a balance between expanding market forces and social development policy to an attitude espousing a neoliberal insistence for deregulation and the strengthening of markets. This change has had negative consequences for employment and labour policy. The relationship between consumption and job security has not been adequately addressed, and the implications of risk and uncertainty for the distribution of income have not been determined. Nor is there any response to the consequences of mass migration following the admission of new member states from Central and Eastern Europe

Tilted: The Familiar Axes of Politics Are Changing, with Momentous Consequences

Economic globalisation and its diverse effects are producing new social and political identities that depart sharply from those forged in the struggles of the past. Colin Crouch presents a guide to the shifting conflict axes within western societies, and their likely consequences

Trade Unions and Local Development Networks

Local economic development is becoming an increasingly important policy arena as governments lose many of their former capacities for economic intervention. Governments can act to promote the competitiveness of firms by improving the ‘collective competition goods’ that are available to firms. An important class of such goods operate at the local level. Examples include improving local infrastructure and policies for ‘place branding’. Unions are often left out of the key groups that formulate policies of this kind, but as this becomes a field of importance to workers, and where economic and social policy come together, unions have a major contribution to make. However, it is difficult for unions to make a significant contribution because of their past record of marginalisation and the difficulty they may have in acquiring competence in this area. The importance of the social issues involved and the democratic deficit of many of the arrangements for managing major urban agglomerations make it urgent that unions grasp this challenge.Die lokale Wirtschaftsentwicklung entwickelt sich zu einem zunehmend wichtigen politischen Schauplatz, da die Regierungen viele der Interventionsmöglichkeiten, die sie früher im Wirtschaftsbereich hatten, verloren haben. Sie können die Wettbewerbsfähigkeit der Unternehmen aktiv fördern, indem sie die „kollektiven Wettbewerbsgüter” verbessern, die den Unternehmen zur Verfügung stehen. Eine wichtige Gruppe dieser Güter ist auf der lokalen Ebene angesiedelt, z.B. die Verbesserung der lokalen Infrastruktur und „Place Branding”-Strategien. Die Gewerkschaften werden bei der Erarbeitung solcher Strategien meist nicht beteiligt, obgleich sie zu diesem Bereich, der auch für Arbeitnehmer an Bedeutung gewinnt und wirtschafts- und sozialpolitische Aspekte miteinander verknüpft, einen wesentlichen Beitrag zu leisten haben. Für die Gewerkschaften ist es jedoch schwierig, einen bedeutenden Beitrag zu leisten, einerseits weil sie in der Vergangenheit marginalisiert worden sind und andererseits weil sie möglicherweise Schwierigkeiten haben, Zuständigkeiten in diesem Bereich zu erlangen. Angesichts der großen Bedeutung der damit verbundenen sozialen Fragen und des demokratischen Defizits bei vielen Maßnahmen zur Planung in großen Ballungsgebieten ist es dringend notwendig, dass die Gewerkschaften diese Herausforderung aufgreifen

Helioseismic holography of simulated sunspots: magnetic and thermal contributions to travel times

Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path towards inversions for sunspot structure.Comment: Accepted for publication in The Astrophysical Journa

Sources Of Student Engagement In Introductory Physics For Life Sciences

We explore the sources of student engagement with curricular content in an Introductory Physics for Life Science (IPLS) course at Swarthmore College. Do IPLS students find some life-science contexts more interesting than others, and, if so, what are the sources of these differences? We draw on three sources of student data to answer this question: (1) quantitative survey data illustrating how interested students were in particular contexts from the curriculum, (2) qualitative survey data in which students describe the source of their interest in these particular contexts, and (3) interview data in which students reflect on the contexts that were and were not of interest to them. We find that examples that make interdisciplinary connections with students’ other coursework in biology and chemistry, and examples that make connections to what students perceive to be the “real world,” are particularly effective at fostering interest. More generally, students describe being deeply engaged with contexts that foster a sense of coherence or have personal meaning to them. We identify various “engagement pathways” by which different life-science students engage with IPLS content, and suggest that a curriculum needs to be flexible enough to facilitate these different pathways

Coal-rock interface detector

A coal-rock interface detector is presented which employs a radioactive source and radiation sensor. The source and sensor are separately and independently suspended and positioned against a mine surface of hydraulic pistons, which are biased from an air cushioned source of pressurized hydraulic fluid

Structure, biologic properties, and expression of surfactant protein D (SP-D)

AbstractSurfactant protein D (SP-D) is a member of the family of collagenous host defense lectins, designated collectins. There is increasing evidence that SP-D, like SP-A, is an important component of the innate immune response to microbial challenge, and that it may participate in other aspects of immune and inflammatory regulation within the lung. SP-D binds to glycoconjugates and/or lipid moieties expressed by a wide variety of microorganisms and certain other organic particles, in vitro. Although binding may facilitate microbial clearance through aggregation or other direct effects on the organism, SP-D also has the capacity to modulate leukocyte function, and in some circumstances, to enhance their killing of microorganisms