The Spectral Energy Distribution of Self-gravitating Interstellar Clouds I. Spheres

We derive the spectral energy distribution (SED) of dusty, isothermal, self gravitating, stable and spherical clouds externally heated by the ambient interstellar radiation field. For a given radiation field and dust properties, the radiative transfer problem is determined by the pressure of the surrounding medium and the cloud mass expressed as a fraction of the maximum stable cloud mass above which the clouds become gravitational unstable. To solve the radiative transfer problem a ray-tracing code is used to accurately derive the light distribution inside the cloud. This code considers both non isotropic scattering on dust grains and multiple scattering events. The dust properties inside the clouds are assumed to be the same as in the diffuse interstellar medium in our galaxy. We analyse the effect of the pressure, the critical mass fraction, and the ISRF on the SED and present brightness profiles in the visible, the IR/FIR and the submm/mm regime with the focus on the scattered emission and the thermal emission from PAH-molecules and dust grains.Comment: accepted for publication in ApJS, May 2008, v176n1 issu

Laterality of motor activity during normal and disturbed sleep

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Multicomponent aerosol dynamics model UHMA: model development and validation

A size-segregated aerosol dynamics model UHMA (University of Helsinki Multicomponent Aerosol model) was developed for studies of multicomponent tropospheric aerosol particles. The model includes major aerosol microphysical processes in the atmosphere with a focus on new particle formation and growth; thus it incorporates particle coagulation and multicomponent condensation, applying a revised treatment of condensation flux onto free molecular regime particles and the activation of nanosized clusters by organic vapours (Nano-K&#246;hler theory), as well as recent parameterizations for binary H₂SO₄-H₂O and ternary H₂SO₄-NH₃-H₂O homogeneous nucleation and dry deposition. The representation of particle size distribution can be chosen from three sectional methods: the hybrid method, the moving center method, and the retracking method in which moving sections are retracked to a fixed grid after a certain time interval. All these methods can treat particle emissions and atmospheric transport consistently, and are therefore suitable for use in large scale atmospheric models. In a test simulation against an accurate high resolution solution, all the methods showed reasonable treatment of new particle formation with 20 size sections although the hybrid and the retracking methods suffered from artificial widening of the distribution. The moving center approach, on the other hand, showed extra dents in the particle size distribution and failed to predict the onset of detectable particle formation. In a separate test simulation of an observed nucleation event, the model captured the key qualitative behaviour of the system well. Furthermore, its prediction of the organic volume fraction in newly formed particles, suggesting values as high as 0.5 for 3&ndash;4 nm particles and approximately 0.8 for 10 nm particles, agrees with recent indirect composition measurements

Nanostructuring Graphene by Dense Electronic Excitation

The ability to manufacture tailored graphene nanostructures is a key factor to fully exploit its enormous technological potential. We have investigated nanostructures created in graphene by swift heavy ion induced folding. For our experiments, single layers of graphene exfoliated on various substrates and freestanding graphene have been irradiated and analyzed by atomic force and high resolution transmission electron microscopy as well as Raman spectroscopy. We show that the dense electronic excitation in the wake of the traversing ion yields characteristic nanostructures each of which may be fabricated by choosing the proper irradiation conditions. These nanostructures include unique morphologies such as closed bilayer edges with a given chirality or nanopores within supported as well as freestanding graphene. The length and orientation of the nanopore, and thus of the associated closed bilayer edge, may be simply controlled by the direction of the incoming ion beam. In freestanding graphene, swift heavy ion irradiation induces extremely small openings, offering the possibility to perforate graphene membranes in a controlled way.Comment: 16 pages, 5 figures, submitted to Nanotechnolog

The Right to participate:Beyond the instrumental use of stakeholders in imagining the lived experience of the city

By taking a closer look at the assumptions and methods driving the current citizen participation paradigm, this paper addresses the risk of tokenistic involvement of citizens and other stakeholders in approaches such as co-design and citizen science. These participatory processes are highly demanding to plan, difficult to manage, and can lead to serious misinterpretations of the citizens’ intentions and behaviour: reimagining participatory processes would be thus in order (Bannon &amp; al. 2018). Encouraged by this, in this paper we look into 1) what type of alternative forms of participation might there be and 2) in which ways they restore ownership. We then proceed to ask further 3) how design can contribute to creating such alternative forms of citizen participation. As a case we refer to the sharp distinction distinguishable between the digital representation of urban existence and the lived experience of urban dwellers. The critical theoretical impetus can be traced back to (at least) the critical engagement with digital media in works such as “On the Internet” (Dreyfus 2001), which highlighted the absence of bodies and embodiment in digital environments. While we do agree that we need to remain critical about what aspects of human existence can be represented in digital media and which cannot, we also recognise that we are not merely the dot on a map, yet, “being a dot on a map” is part of our lived experience as urban subjects (Kingwell, 2008). In our paper, we will explore the role that digital representations of oneselves get in the participatory approaches to the experience of the city. We will address the everyday use of such services as digital maps as well as the potential use of such self-representations in artistic and educational practices to re-materialize our digital doubles and data traces. The proposed paper contributes to bridging recent developments in design ethics and participatory methods in a way which further underlines the importance of understanding the citizens’ perspective in urban design processes. This means also further emphasis on interpersonal and relational aspects of citizen participation as well as probing into more experimental forms of research design in the urban studies context. References: Bannon, Liam, Jeffrey Bardzell, and Susanne Bødker 2018. “Reimagining participatory design”, Interactions 26, 1 (Jan/Feb 2019), pp. 26–32. https://doi.org/10.1145/3292015 Dreyfus, Hubert L. 2001. On the internet / Hubert Dreyfus. London &amp; New York: Routledge. Kingwell, M. 2008. Concrete reveries: Consciousness and the city. London: Penguin

CCN activation and cloud processing in simplified sectional aerosol models with low size resolution

International audienceWe investigate the influence of low size resolution, typical to sectional aerosol models in large scale applications, on cloud droplet activation and cloud processing of aerosol particles. A simplified cloud scheme with five approaches to determine the fraction of activated particles is compared with a detailed reference model under different atmospheric conditions. In general, activation approaches which assume a distribution profile within the critical model size sections predict the cloud droplet concentration most accurately under clean and moderately polluted conditions. In such cases, the deviation from the reference simulations is below 15% except for very low updraft velocities. In highly polluted cases, the concentration of cloud droplets is significantly overestimated due to the inability of the simplified scheme to account for the kinetic limitations of the droplet growth. Of the profiles examined, taking into account the local shape of the particle size distribution is the most accurate although in most cases the shape of the profile has little relevance. While the low resolution cloud model cannot reproduce the details of the out-of-the-cloud aerosol size distribution, it captures well the amount of sulphate produced in aqueous-phase reactions as well as the distribution of the sulphate between the cloud droplets. Overall, the simplified cloud scheme with low size resolution performs well for clean and moderately polluted regions that cover most of the Earth's surface and is therefore suitable for large scale models

A phylogeny of members of the family Taeniidae based on the mitochondrial cox1 and nad1 gene data

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Technical note: Analytical formulae for the critical supersaturations and droplet diameters of CCN containing insoluble material

International audienceIn this paper, we consider the cloud drop activation of aerosol particles consisting of water soluble material and an insoluble core. Based on the Köhler theory, we derive analytical equations for the critical diameters and supersaturations of such particles. We demonstrate the use of the equations by comparing the critical supersaturations of particles composed of ammonium sulfate and insoluble substances with those of model organic particles with varying molecular sizes

On the hygroscopic growth of ammoniated sulfate particles of non-stoichiometric composition

International audienceThe hygroscopic growth of ammoniated sulfate particles was studied by measurements and model calculations for particles with varying ammonium-to-sulfate ratio. In the measurements, the ammonium-to-sulfate ratio was adjusted by using mixtures of ammonium sulfate and ammonium bisulfate in generating the solid particles. The hygroscopic growth was measured using a tandem differential mobility analyzer. The measurements were simulated using a thermodynamical equilibrium model. The calculations indicated that the solid phases in particle with ammonium-to-sulfate ratio between 1.5?2, were ammonium sulfate and letovicite. Both in the calculations and in the experiments the hygroscopic growth was initiated at relative humidities less than the theoretical deliquescence relative humidity of these particles. This indicates that the particles were multi-phase particles including solids and liquids. The equilibrium model yielded a satisfactory prediction of the hygroscopic growth of particles generated from a solution with 1:1 mass ratio between dissolved ammonium sulfate and ammonium bisulfate. However, for particles with 3:1 and 10:1 mass ratios, the model predictions overestimated the growth at relative humidities between about 60% and the point of complete deliquescence (close to 80% RH). In contrast, a model, in which letovicite was allowed to dissolve only after complete dissolution of ammonium sulfate, reproduced the observations well. This indicates that the dry particles had a letovicite core surrounded by an ammonium sulfate shell