Making identity assurance and authentication strength work for federated infrastructures

In both higher Research and Education (R&E) as well as in research-/ e-infrastructures (in short: infrastructures), federated access and single sign-on by way of national federations, operated in most cases by NRENs, are used as a means to provide users with access to a variety of services. Whereas in national federations institutional accounts, e.g. provided by a university, are typically used to access services, many infrastructures also accept other sources of identity: provided by \u27\u27community identity providers\u27\u27, social identity providers, or governmental IDs. In order to assess and communicate the quality of identities being used and authentications being performed, so called Level of Assurance (LoA) frameworks are used. Because sophisticated LoA frameworks like NIST 800-63-3, Kantara IAF 1420 or eIDAS regulation are often considered too complex to be used in R&E scenarios, the REFEDS Assurance Suite, a more lightweight approach, has been developed. To select an appropriate assurance level, Service Providers need to weigh risks and potential harms in relation to the kind of service they offer. However, the management of risks is often implicitly assumed and little or no guidance to determine the appropriate assurance level is given. In this paper, first, common LoA frameworks and their relation to risk management are investigated. Following that, their components are compared against the REFEDS Assurance Suite using a graphical representation. The focus of this paper lies in providing guidance and best practices based on example scenarios for both Service Providers to request the appropriate REFEDS assurance level, as well as for Identity Provider operators on how to implement REFEDS assurance components

The long-period Galactic Cepheid RS Puppis - II. 3D structure and mass of the nebula from VLT/FORS polarimetry

The long-period Cepheid RS Pup is surrounded by a large dusty nebula reflecting the light from the central star. Due to the changing luminosity of the central source, light echoes propagate into the nebula. This remarkable phenomenon was the subject of Paper I.The origin and physical properties of the nebula are however uncertain: it may have been created through mass loss from the star itself, or it could be the remnant of a pre-existing interstellar cloud. Our goal is to determine the 3D structure of the nebula, and estimate its mass. Knowing the geometrical shape of the nebula will also allow us to retrieve the distance of RS Pup in an unambiguous manner using a model of its light echoes (in a forthcoming work). The scattering angle of the Cepheid light in the circumstellar nebula can be recovered from its degree of linear polarization. We thus observed the nebula surrounding RS Pup using the polarimetric imaging mode of the VLT/FORS instrument, and obtained a map of the degree and position angle of linear polarization. From our FORS observations, we derive a 3D map of the distribution of the dust, whose overall geometry is an irregular and thin layer. The nebula does not present a well-defined symmetry. Using a simple model, we derive a total dust mass of M(dust) = 2.9 +/- 0.9 Msun for the dust within 1.8 arcmin of the Cepheid. This translates into a total mass of M(gas+dust) = 290 +/- 120 Msun, assuming a dust-to-gas ratio of 1.0 +/- 0.3 %. The high mass of the dusty nebula excludes that it was created by mass-loss from the star. However, the thinness nebula is an indication that the Cepheid participated to its shaping, e.g. through its radiation pressure or stellar wind. RS Pup therefore appears as a regular long-period Cepheid located in an exceptionally dense interstellar environment.Comment: 14 pages, 21 figures. Accepted for publication in A&

On the evolutionary and pulsation mass of Classical Cepheids: III. the case of the eclipsing binary Cepheid CEP0227 in the Large Magellanic Cloud

We present a new Bayesian approach to constrain the intrinsic parameters (stellar mass, age) of the eclipsing binary system CEP0227 in the LMC. We computed evolutionary models covering a broad range in chemical compositions and in stellar mass. Independent sets of models were constructed either by neglecting or by including a moderate convective core overshooting (beta=0.2) during central H-burning phases. Models were also constructed either by neglecting or by assuming a canonical (eta=0.4,0.8) or an enhanced (eta=4) mass loss rate. The solutions were computed in three different planes: luminosity-temperature, mass-radius and gravity-temperature. By using the Bayes Factor, we found that the most probable solutions were obtained in the gravity-temperature plane with a Gaussian mass prior distribution. The evolutionary models constructed by assuming a moderate convective core overshooting (beta=0.2) and a canonical mass loss rate (eta=0.4) give stellar masses for the primary Cepheid M=4.14^{+0.04}_{-0.05} M_sun and for the secondary M=4.15^{+0.04}_{-0.05} M_sun that agree at the 1% level with dynamical measurements. Moreover, we found ages for the two components and for the combined system t=151^{+4}_{-3} Myr that agree at the 5% level. The solutions based on evolutionary models that neglect the mass loss attain similar parameters, while those ones based on models that either account for an enhanced mass loss or neglect convective core overshooting have lower Bayes Factors and larger confidence intervals. The dependence on the mass loss rate might be the consequence of the crude approximation we use to mimic this phenomenon. By using the isochrone of the most probable solution and a Gaussian prior on the LMC distance, we found a distance modulus 18.53^{+0.02}_{-0.02} mag and a reddening value E(B-V)= 0.142^{+0.005}_{-0.010} mag that agree well with literature estimates.Comment: Accepted for publication in ApJ. 17 pages, 9 figure

Liquid Xenon Detectors for Positron Emission Tomography

PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated performance shows that an energy resolution of <10% (FWHM) and a sensitivity of 15% are achievable. First tests with a prototype TPC indicate position resolution <1 mm (FWHM).Comment: Paper presented at the International Nuclear Physics Conference, Vancouver, Canada, 201

Solidification of oils and organic liquids

The suitability of selected solidification media for application in the disposal of low-level oil and other organic liquid wastes has been investigated. In the past, these low-level wastes (LLWs) have commonly been immobilized by sorption onto solid absorbents such as vermiculite or diatomaceous earth. Evolving regulations regarding the disposal of these materials encourage solidification. Solidification media which were studied include Portland type I cement; vermiculite plus Portland type I cement; Nuclear Technology Corporation's Nutek 380-cement process; emulsifier, Portland type I cement-sodium silicate; Delaware Custom Materiel's cement process; and the US Gypsum Company's Envirostone process. Waste forms have been evaluated as to their ability to reliably produce free standing monolithic solids which are homogeneous (macroscopically), contain < 1% free standing liquids by volume and pass a water immersion test. Solidified waste form specimens were also subjected to vibratory shock testing and flame testing. Simulated oil wastes can be solidified to acceptable solid specimens having volumetric waste loadings of less than 40 volume-%. However, simulated organic liquid wastes could not be solidified into acceptable waste forms above a volumetric loading factor of about 10 volume-% using the solidification agents studied

Zmym4 is required for early cranial gene expression and craniofacial cartilage formation

The Six1 transcription factor plays important roles in the development of cranial sensory organs, and point mutations underlie craniofacial birth defects. Because Six1’s transcriptional activity can be modulated by interacting proteins, we previously screened for candidate interactors and identified zinc-finger MYM-containing protein 4 (Zmym4) by its inclusion of a few domains with a bona fide cofactor, Sine oculis binding protein (Sobp). Although Zmym4 has been implicated in regulating early brain development and certain cancers, its role in craniofacial development has not previously been described

Dynamic correlations in symmetric electron-electron and electron-hole bilayers

The ground-state behavior of the symmetric electron-electron and electron-hole bilayers is studied by including dynamic correlation effects within the quantum version of Singwi, Tosi, Land, and Sjolander (qSTLS) theory. The static pair-correlation functions, the local-field correction factors, and the ground-state energy are calculated over a wide range of carrier density and layer spacing. The possibility of a phase transition into a density-modulated ground state is also investigated. Results for both the electron-electron and electron-hole bilayers are compared with those of recent diffusion Monte Carlo (DMC) simulation studies. We find that the qSTLS results differ markedly from those of the conventional STLS approach and compare in the overall more favorably with the DMC predictions. An important result is that the qSTLS theory signals a phase transition from the liquid to the coupled Wigner crystal ground state, in both the electron-electron and electron-hole bilayers, below a critical density and in the close proximity of layers (d <~ r_sa_0^*), in qualitative agreement with the findings of the DMC simulations.Comment: 13 pages, 11 figures, 2 table

Quasiparticle Effective Mass for the Two- and Three-Dimensional Electron Gas

We calculate the quasiparticle effective mass for the electron gas in two and three dimensions in the metallic region. We employ the single particle scattering potential coming from the Sj\"{o}lander-Stott theory and enforce the Friedel sum rule by adjusting the effective electron mass in a scattering calculation. In 3D our effective mass is a monotonically decreasing function of $r_s$ throughout the whole metallic domain, as implied by the most recent numerical results. In 2D we obtain reasonable agreement with the experimental data, as well as with other calculations based on the Fermi liquid theory. We also present results of a variety of different treatments for the effective mass in 2D and 3D.Comment: 12 pages, 2 figure