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See detailOpen source programming: a new hope for psychometric research
Magis, David ULg

Conference (2016, July 14)

Current psychometric research is most often supported by computer software. New research perspectives often imply intensive simulation studies to validate the tested theories or hypotheses, and therefore ... [more ▼]

Current psychometric research is most often supported by computer software. New research perspectives often imply intensive simulation studies to validate the tested theories or hypotheses, and therefore require accurate, fast and stable implementation. To this regards, open source programming (such as in the R language) is a promising approach allowing for flexible implementation, data generation, replication of studies, and worldwide dissemination. The purpose of this talk is to illustrate how psychometrics and open source programming (with special emphasis on the R language) can interact and contribute to each other, by means of some selected examples. Several topics will be illustrated, among others: why open source programming is (to my opinion) as important as psychometric research; why we need for stable and complete implementation of psychometric and statistical routines for research purposes (for e.g., CAT); how accurate implementation of IRT routines can lead to unexpected theoretical results; why (and how) open source software can be valued as research output. Most examples will arise from the CAT framework and the R package catR for simulating CAT patterns. [less ▲]

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See detailMomentum- and Heat-Flux Parameterization at Dome C, Antarctica: A Sensitivity Study
Vignon, Etienne; Genthon, Christophe; Barral, Hélène et al

in Boundary-Layer Meteorology (2016)

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See detailSanté et sécurité au travail: un modèle intégratif pour prédire les comportements de sécurité.
Laurent, Julie ULg; Chmiel, Nik; Hansez, Isabelle ULg

Conference (2016, July 13)

INTRODUCTION. La santé et la sécurité sont deux thématiques qui ont souvent été traitées séparément dans la littérature scientifique. Hansez et Chmiel (2010) ont démontré la pertinence d’utiliser le ... [more ▼]

INTRODUCTION. La santé et la sécurité sont deux thématiques qui ont souvent été traitées séparément dans la littérature scientifique. Hansez et Chmiel (2010) ont démontré la pertinence d’utiliser le modèle ‘demandes-ressources’ (Bakker et Demerouti, 2007) afin d’expliquer les comportements de sécurité au travail. La présente étude propose d’étendre ce modèle en y incluant un processus d’échange social, spécifiquement lié à la sécurité, en plus des processus motivationnel, cognitif-énergétique et instrumental. METHODES. Notre échantillon est composé de 1922 travailleurs d’une entreprise métallurgique belge. Notre modèle théorique a été testé à l’aide de la modélisation par équations structurales, avec le logiciel MPlus. RESULTATS. Le modèle final présente des indices d’adéquation acceptables (²=3346.63, dl=678, RMSEA=.04, CFI=.92, NNFI=.91). Les résultats montrent que les quatre processus psychologiques sont impliqués. Les violations « situationnelles » (i.e. le fait de commettre des infractions qui sont dues à des lacunes de l’organisation et sans lesquelles le travail ne pourrait pas être réalisé) sont expliquées par (1) un processus motivationnel, puisque les ressources encouragent les travailleurs à être stimulés par leur travail, et ainsi à moins commettre ce type d’infractions (2) un processus instrumental, puisque percevoir l’implication de son management dans la sécurité est associé directement à moins de violations situationnelles, et par (3) un processus social, puisque les ressources de travail permettent aux employés de percevoir l’implication de leur management dans la sécurité, et de répondre à cet intérêt en considérant la sécurité comme faisant partie de leur rôle, ce qui les encourage ensuite à participer à des activités volontaires liées à la sécurité. D’autre part, les violations de « routine » (i.e. le fait de « prendre des raccourcis » et de ce fait ne pas respecter les procédures de sécurité) sont expliquées par les mêmes processus d’échange social et motivationnel, mais aussi par un processus cognitif-énergétique, puisque des conditions de travail contraignantes peuvent mener à plus de stress, associé à son tour à plus de violations de routine. DISCUSSION. La principale limitation de cette étude est la nature auto-rapportée des données, pouvant mener à différents biais. Néanmoins, différentes implications pratiques peuvent être mises en évidence. Les entreprises désireuses de réduire les violations des règles de sécurité devraient considérer à la fois les processus spécifiquement liés à la sécurité et des processus psychologiques plus larges. Par exemple, outre l’importance d’améliorer les conditions de travail considérées comme des ressources, il est important de garder à l’esprit que ces ressources déterminent des processus complexes d’échanges sociaux spécifiquement liés à la sécurité, à travers l’influence primordiale du management. [less ▲]

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See detailA Crypt of Swipes. Charles Burns Haunted by Tintin
Crucifix, Benoît ULg

Conference (2016, July 13)

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See detailShaping (im)mobility in border camps: a case study of the transformation of Calais camps and its actors
Da Silva, Amanda Carolina ULg

Conference (2016, July 13)

This paper explores the transition of informal temporary camps on the French border to a sustainable state, and discusses how local policy decisions and non-state actors worked together for the ... [more ▼]

This paper explores the transition of informal temporary camps on the French border to a sustainable state, and discusses how local policy decisions and non-state actors worked together for the implementation of a semi-permanent exclusion system based on the refugee crisis. I observe this issue as a result of a securitization process. The securitization apparatus (speech acts and policies), produced the immobility of a group. In the other hand actors will emerge to produce mobility. When a situation is defined as a crisis, atypical actions can be employed to protect the «political community». I started from the assumption that dialectic relation between securitization and camps actors had a high impact on the projects of refugees, and so long in their mobility. This is a question of integration policies at the local level. I aim to highlight the local level relevance, where the integration is primarily implemented, and therefore local and regional context should matter as much as the national model for integration (Martiniello, 2013). In Calais, due to the lack of immigrants policies, civilians associations started to react and build informal camps, but due to recent "crisis" the Stat concentrated all refugees in a single camp, 6 kilometers from the city center, called bidonville. [less ▲]

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See detailOperational costs and externalities in optimal intermodal network design
Mostert, Martine ULg; Limbourg, Sabine ULg; Caris, An

Conference (2016, July 13)

Transportation of goods is essential for the economy but also leads to harmful impacts related to human health aspects. Intermodal transport is promoted by Europe to reduce these negative externalities ... [more ▼]

Transportation of goods is essential for the economy but also leads to harmful impacts related to human health aspects. Intermodal transport is promoted by Europe to reduce these negative externalities. The objective of this paper is to analyze at the strategic level how the flow repartition varies between three modes (road, intermodal rail and intermodal inland waterway) according to different implemented policies. A mathematical allocation model is developed and tested on the Belgian case study, in order to determine the observed changes between the single minimization of (operational or health-related external) costs and the introduction of additional road taxes. [less ▲]

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See detailOn the role of interfacial reactions, dissolution and secondary precipitation during the laser additive manufacturing of metal matrix composites - A Review
Mertens, Anne ULg; Lecomte-Beckers, Jacqueline ULg

in Shishkovsky, I.V. (Ed.) New Trends in 3D Printing (2016)

Since current trends in the transportation, energy or mechanical industries impose increasingly demanding service conditions for metallic parts, metal matrix composites (MMC) are the object of a growing ... [more ▼]

Since current trends in the transportation, energy or mechanical industries impose increasingly demanding service conditions for metallic parts, metal matrix composites (MMC) are the object of a growing interest. Powder-based laser additive manufacturing, that allows to make parts with complex shapes, appears particularly adapted for the production of MMCs. This paper reviews the current state-of-the-art in the production of MMCs by additive processes, with the aim of assessing the potentials and difficulties offered by these techniques. Two main processing routes are envisaged i.e. (1) the processing of ex-situ composites in which the reinforcing phase as a powder – often of ceramic particles − is directly mixed with the powder of the matrix alloy, and both powders are simultaneously processed by the laser. (2) Alternatively, the reinforcing phase can be produced in-situ by a chemical reaction during the fabrication of the composite. For both processing routes, a careful control is needed to overcome challenges brought e.g. by the behaviour of the reinforcement particles in the laser beam, by changes in laser absorptivity or by the dissolution of the reinforcing particles in the molten metal, in order to produce metal matrix composites with enhanced usage properties. [less ▲]

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See detailModelling of an automotive multi-evaporator air-conditioning system
Gillet, Thomas ULg; Lemort, Vincent ULg; Rullière, Romuald et al

Scientific conference (2016, July 13)

An automotive multi-evaporator air conditioning system, which is composed of two evaporators and a secondary fluid cooler, was modeled using the LMS Imagine.Lab Amesim® 1D software. The present study ... [more ▼]

An automotive multi-evaporator air conditioning system, which is composed of two evaporators and a secondary fluid cooler, was modeled using the LMS Imagine.Lab Amesim® 1D software. The present study focuses on understanding the dynamic coupling of the several loop components such as the three evaporators having different cooling capacities. This kind of multi-evaporator air-conditioning system has a number of technological barriers that must be overcome. Understanding the behavior of their respective expansion devices and the choice of these latter is also essential to control properly the transient phase and ensure an optimal operation of the air-conditioning system. In order to study the behavior of the loop, step disturbances were simulated on an operating point at medium and high load. The impact of these disturbances on the stability of the supplied cooled air temperature is analyzed for two types of expansion valve. Initial results show that the thermostatic expansion valves can cause instabilities. Furthermore, the electronic expansion valves have to be regulated with an advanced control in order to use their full potential and to try to achieve desired results. [less ▲]

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See detailGamma-Ray Spectrometry: Experimental Measurement and Monte Carlo Simulation using GEANT4 toolkit
Guembou Shouop, Cébastien Joel ULg; Ndontchueng Moyo, Maurice; Chene, Grégoire ULg et al

Poster (2016, July 13)

Nowadays the precision in the measurement has become a challenge for physicists. That is why in recent decades, the interest is very granted to simulation. Since 1940, the method Monte Carlo is more ... [more ▼]

Nowadays the precision in the measurement has become a challenge for physicists. That is why in recent decades, the interest is very granted to simulation. Since 1940, the method Monte Carlo is more useful for validation and even for prediction of the results of the experiment. The aim of this study is to validate experimental models. Our laboratories are equipped with HPGe gamma spectrometers for measuring the natural radioactivity, it becomes interesting to compare and even to improve the performance of our system. Geant4 is used for the construction of the geometry of detection, the physics processes and the primary particles. First and prliminary result was prsented in this paper. [less ▲]

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See detail“Who Cares for Those Who Cared? Ethnography on Ageing Migrant Domestic Workers Negotiations for Social Protection “
Vivas Romero, Maria ULg

Scientific conference (2016, July 12)

How and through which practices do Ageing Migrant Domestic Workers negotiate their access to social protection across borders? How are these negotiations influenced both by their intersecting gender, race ... [more ▼]

How and through which practices do Ageing Migrant Domestic Workers negotiate their access to social protection across borders? How are these negotiations influenced both by their intersecting gender, race, class, generational standpoints and their transnational family relations? This contribution deals with these questions and focuses on the case of Peruvian and Colombian Ageing Migrant Domestic Workers in the city of Brussels. Such migrants share a paradoxical positioning as they contribute productively and reproductively to the development of their receiving and sending societies but experience a lack of formal and informal social protection on both sides. This analysis first maps through a moving ethnography the practices they use to negotiate their access to Social Protection in the areas of: 1- access to labor, 2- social security entitlement and portability, 4- housing and 3- informal symbolic-practical care. Secondly, it theorizes these practices as an assemblage of social protection that’s simultaneously made out of transnational interpersonal relationships and formal support systems. Thirdly, building from the work of Amelina et al, (2012) Transnational and Intersectional lens are used to analyze how the effectiveness of such assemblage is simultaneously affected by these actor’s gender, race, class and generational positioning within the global reproduction of labor as well as by their transnational family relations. Concluding, it’s argued such assemblage of protection increases ageing migrants’ life chances but reproduces and produces social- inequalities at the local, transnational and global level. This contribution provides a glance at how transnational needs for social protection are negotiated across borders. Furthermore, it’s relevant in a context of increasing human mobility where inequalities in access to social protection emerge as a public transnational social question that is relevant both for academics and policy makers. [less ▲]

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See detailArchitectural and Environmental Housing Typology Analysis in Huamachuco, Peru
Meliani, Houmam ULg; Teller, Jacques ULg; Attia, Shady ULg

in La Roche, Pablo; Schiler, Marc (Eds.) Passive and Low Energy Architecture Conference (2016, July 12)

This work focuses on the city of Huamachuco, a town 3200 meters above sea level in Northern Peru. The main aim of this study is to share and disseminate technological knowledge on architecture, building ... [more ▼]

This work focuses on the city of Huamachuco, a town 3200 meters above sea level in Northern Peru. The main aim of this study is to share and disseminate technological knowledge on architecture, building technology and lifestyle of Huamachuco inhabitants. The paper objective is to (1) highlight the concept of architectural quality in Huamachuco, (2) compare the living environment of existing traditional dwellings in comparison with newly constructed concrete dwellings, and to (3) identify the reasons for neglecting ecological construction technologies and materials in the new built environment. The research methodology went through different phases that range from qualitative data collection and quantitative measuring, to data analysis and findings reporting. Firstly, a typological study was conducted visiting 110 houses. The typological study enabled us to describe and understand the housing typologies and classify those under four major typologies according to their construction techniques: 1) adobe, 2) rammed earth, 3) concrete and 4) mixed technique. Secondly, detailed field studies were conducted for representative houses representing the four categories. Finally, 10 houses have been thoroughly audited for using measuring equipment to collect data related to temperature, relative humidity, carbon dioxide concentration, lighting intensity, and envelope thermography. [less ▲]

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See detailThe Methods of Managgement: An Answer to the crisis
Robert, Jocelyne ULg

Conference (2016, July 12)

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See detailFailure multiscale simulations of composite laminates based on a non-local mean-field damage-enhanced homogenization
Wu, Ling ULg; Adam, Laurent; Doghri, Issam et al

Conference (2016, July 12)

A multiscale method is developed to study the failure of carbon fiber reinforced composites. In order to capture the intra-laminar failure, a non-local mean-field homogenization (MFH) method accounting ... [more ▼]

A multiscale method is developed to study the failure of carbon fiber reinforced composites. In order to capture the intra-laminar failure, a non-local mean-field homogenization (MFH) method accounting for the damage evolution of the matrix phase of the composite material [1] is considered. In that formulation, an incremental-secant MFH approach is used to account for the elastic unloading of the fibers during the strain softening of the matrix. In order to avoid the strain/damage localization caused by the matrix material softening, an implicit non-local method [2] was reformulated to account for the composite material anisotropy. As a result, accurate predictions of the composite softening behavior and of the different phases response is possible, even for volume ratios of inclusions around 60%. In particular it is shown that the damage propagation direction in each ply follows the fiber orientation in agreement with experimental data. The delamination process is modeled by recourse to a hybrid discontinuous Galerkin (DG)/ extrinsic cohesive law approach. As for the extrinsic cohesive law (ECL), which represents the fracturing response only, and for which cohesive elements are inserted at failure onset, the method does not suffer from a mesh-dependent effect. However, because of the underlying discontinuous Galerkin method, interface elements are present since the very beginning of the simulation avoiding the need to propagate topological changes in the mesh with the propagation of the delamination. Moreover, the pre-failure response is accurately captured by the material law though the DG implementation, by contrast to usual intrinsic cohesive laws. As a demonstration of the efficiency and accuracy of the method, a composite laminate with a quasi-isotropic sequence ([90/45/-45/90/0]S) and an open-hole geometry is studied using the multiscale method [3] and the results are compared to experimental data. The numerical model is found to predict the damage bands along the fiber directions as observed in the experimental samples inspected by X-ray computed tomography (XCT). Moreover, the predicted delamination pattern is found to match the experimental observations. REFERENCES [1] L. Wu, L. Noels, L. Adam, I. Doghri, An implicit-gradient-enhanced incremental-secant mean- field homogenization scheme for elasto-plastic composites with damage, International Journal of Solids and Structures, 50, 3843-3860, 2013. [2] R. Peerlings, R. de Borst, W. Brekelmans, S. Ayyapureddi, Gradient-enhanced damage for quasi-brittle materials. International Journal for Numerical Methods in Engineering, 39, 3391-3403, 1996. [3] L. Wu, F. Sket, J.M. Molina-Aldareguia, A. Makradi, L. Adam, I. Doghri, L. Noels, A study of composite laminates failure using an anisotropic gradient-enhanced damage mean-field homogenization model, Composite Structures, 126, 246–264, 2015. [less ▲]

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See detailMean-Field-Homogenization-based stochastic multiscale methods for composite materials
Wu, Ling ULg; Lucas, Vincent ULg; Adam, Laurent et al

Conference (2016, July 12)

When considering a homogenization-based multiscale approach, at each integration-point of the macro-structure, the material properties are obtained from the resolution of a micro-scale boundary value ... [more ▼]

When considering a homogenization-based multiscale approach, at each integration-point of the macro-structure, the material properties are obtained from the resolution of a micro-scale boundary value problem. At the micro-level, the macro-point is viewed as the center of a Representative Volume Element (RVE). However, to be representative, the micro-volume-element should have a size much bigger than the micro-structure size. For composite materials which suffer from a large property and geometrical dispersion, either this requires RVE of sizes which cannot usually be obtained numerically, or simply the structural properties exhibit a scatter at the macro-scale. In both cases, the representativity of the micro-scale volume element is lost and Statistical Volume Elements (SVE) [1] should be considered in order to account for the micro-structural uncertainties, which should in turn be propagated to the macro-scale in order to predict the structural properties in a probabilistic way. In this work we propose a non-deterministic multi-scale approach for composite materials following the methodology set in [2]. Uncertainties on the meso-scale properties and their (spatial) correlations are first evaluated through the homogenization of SVEs. This homogenization combines both mean-field method in order to gain efficiency and computational homogenization to evaluate the spatial correlation. A generator of the meso-scale material tensor is then implemented using the spectral method [3]. As a result, a meso-scale random field can be generated, paving the way to the use of stochastic finite elements to study the probabilistic behavior of macro-scale structures. [1] M. Ostoja-Starzewski, X.Wang, Stochastic finite elements as a bridge between random material microstructure and global response, Computer Methods in Applied Mechanics and Engineering, 168, 35–49, 1999. [2] V. Lucas, J.-C. Golinval, S. Paquay, V.-D. Nguyen, L. Noels, L. Wu, A stochastic computational multiscale approach; Application to MEMS resonators. Computer Methods in Applied Mechanics and Engineering, 294, 141–167, 2015. [3] Shinozuka, M., Deodatis, G. Simulation of stochastic processes by spectral representation. Appl. Mech. Rev., 1991: 44(4): 191-204, 1991. [less ▲]

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See detailAccounting conservatism, analysts’ performance and stock market liquidity
Boussaid, Nabila ULg; Hamza, Taher; Sougné, Danielle ULg

Conference (2016, July 11)

This paper investigates whether conditional accounting conservatism has informational benefits to financial market participants. Using a large sample of French firms over the period 2001-2014, we report ... [more ▼]

This paper investigates whether conditional accounting conservatism has informational benefits to financial market participants. Using a large sample of French firms over the period 2001-2014, we report that accounting conservatism improves the firm information environment by providing verifiable information. We specifically document that increases in accounting conservatism are associated with more accurate analyst earnings forecasts, less dispersed forecasts and less volatility in forecast revisions. We also provide evidence that increases in firm accounting conservatism lead to subsequent increases in stock market liquidity, tested on the price impact dimension. Overall, our findings are in line with conservatism being useful to financial markets participants such as financial analysts and investors. [less ▲]

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See detailA Novel Methodology for Hybrid Fire Testing
Sauca, Ana ULg; Gernay, Thomas ULg; Robert, Fabienne et al

in Proceedings of the 6th European Conference on Structural Control (2016, July 11)

This paper describes a novel methodology for conducting stable hybrid fire testing (HTF). During hybrid fire testing, only a part of the structure is tested in a furnace while the reminded structure is ... [more ▼]

This paper describes a novel methodology for conducting stable hybrid fire testing (HTF). During hybrid fire testing, only a part of the structure is tested in a furnace while the reminded structure is calculated separately, here by means of a predetermined matrix. Equilibrium and compatibility at the interface between the tested “physical substructure” and the “numerical substructure” is maintained throughout the test using a dedicated algorithm. The procedures developed so far are sensitive to the stiffness ratio between the physical and the numerical substructure and therefore they can be applied only in some cases. In fire field, the stiffness of the heated physical substructure may change dramatically and the resulting change in stiffness ratio can lead to instability during the test. To overcome this drawback, a methodology independent of the stiffness ratio has been developed, inspired from the Finite Element Tearing and Interconnecting (FETI) method, which has been originally developed for substructuring in numerical analyses. The novel methodology has been successfully applied to a hybrid fire test in a purely numerical environment, i.e. the physical substructure was also modelled numerically. It is shown that stability does not depend on the stiffness ratio and that equilibrium and compatibility can be consistently maintained at the interface during the fire. Finally, the ongoing experimental program aimed at employing and experimentally validating this methodology is described. [less ▲]

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See detailHieroglyphic encoding: The Thot Sign-List (TSL) data model and the hieroglyphic signs in Unicode
Polis, Stéphane ULg; Rosmorduc, Serge

Conference (2016, July 11)

In this paper, we review issues related to the existing hieroglyphic sign-lists, focusing especially on the problematic aspects of the 'Manuel de Codage' (1988) and of the so-called 'Hieroglyphica' (2000 ... [more ▼]

In this paper, we review issues related to the existing hieroglyphic sign-lists, focusing especially on the problematic aspects of the 'Manuel de Codage' (1988) and of the so-called 'Hieroglyphica' (2000) for font-designers and users alike. We propose and discuss a data model for the Thot Sign-List (TSL, in prep.). This data model shall lead to the implementation of a structured and systematically referenced hieroglyphic repertoire, which should ultimately allow a sound extension of the Egyptian Hieroglyphs in Unicode. [less ▲]

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See detailPolarization Measurements of Hot Dust Stars and the Local Interstellar Medium
Marshall, J. P.; Cotton, D. V.; Bott, K. et al

in Astrophysical Journal (2016), 825

Debris discs are typically revealed through the presence of excess emission at infrared wavelengths. Most discs exhibit excess at mid- and far-infrared wavelengths, analogous to the solar system’s ... [more ▼]

Debris discs are typically revealed through the presence of excess emission at infrared wavelengths. Most discs exhibit excess at mid- and far-infrared wavelengths, analogous to the solar system’s Asteroid and Edgeworth-Kuiper belts. Recently, stars with strong (˜1%) excess at near-infrared wavelengths were identified through interferometric measurements. Using the HIgh Precision Polarimetric Instrument, we examined a sub-sample of these hot dust stars (and appropriate controls) at parts-per-million sensitivity in SDSS g‧ (green) and r‧ (red) filters for evidence of scattered light. No detection of strongly polarized emission from the hot dust stars is seen. We, therefore, rule out scattered light from a normal debris disk as the origin of this emission. A wavelength-dependent contribution from multiple dust components for hot dust stars is inferred from the dispersion (the difference in polarization angle in red and green) of southern stars. Contributions of 17 ppm (green) and 30 ppm (red) are calculated, with strict 3-σ upper limits of 76 and 68 ppm, respectively. This suggests weak hot dust excesses consistent with thermal emission, although we cannot rule out contrived scenarios, e.g., dust in a spherical shell or face-on discs. We also report on the nature of the local interstellar medium (ISM), obtained as a byproduct of the control measurements. Highlights include the first measurements of the polarimetric color of the local ISM and the discovery of a southern sky region with a polarization per distance thrice the previous maximum. The data suggest that λ [SUB]max[/SUB], the wavelength of maximum polarization, is bluer than typical. [less ▲]

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