On the relationship between snow grain morphology and in-situ near infrared calibrated reflectance photographs

Seasonal and permanent snow cover a significant portion of our planet, and its impact on climate is significant. Through specific thermophysical properties, snow controls radiative and turbulent fluxes between the ground and the atmosphere, but many aspects of the energy balance are poorly understood due to lingering uncertainties regarding snow properties, such as grain size in particular. Rapid and accurate measurement method has yet to be developed given the reality of field and laboratory logistical constraints, and the sensitivity of snow to any sort of manipulation.In this paper, we investigate the relationship between snow grain morphology parameters measured from visible (traditional) snow grain photography and optical diameter estimated from Near-InfraRed (NIR) reflectance photographs of snow walls. A total of 51 snowpits were analyzed during our International Polar Year field campaign across a 1000 km South-to-North transect over Eastern Canada. We compared the NIR measurements with the theoretical snow albedo model of Kokhanovsky and Zege (2004). Results show the large difference between the snow specific surface area (SSA) of snow grains derived from snow albedo model and the geometrical (visual) diameter. From three different snow grain classes which can be distinguished from traditional photography, linkages can be made with shape factors required in the optical model in order to retrieve optical grain size from NIR photography.     

Map management for robust long-term visual localization of an autonomous shuttle in changing conditions

Multimedia Tools and Applications - Changes in appearance present a tremendous problem for the visual localization of an autonomous vehicle in outdoor environments. Data association between the...     

Monocular Vision for Mobile Robot Localization and Autonomous Navigation

This paper presents a new real-time localization system for a mobile robot. We show that autonomous navigation is possible in outdoor situation with the use of a single camera and natural landmarks. To do that, we use a three step approach. In a learning step, the robot is manually guided on a path and a video sequence is recorded with a front looking camera. Then a structure from motion algorithm is used to build a 3D map from this learning sequence. Finally in the navigation step, the robot uses this map to compute its localization in real-time and it follows the learning path or a slightly different path if desired. The vision algorithms used for map building and localization are first detailed. Then a large part of the paper is dedicated to the experimental evaluation of the accuracy and robustness of our algorithms based on experimental data collected during two years in various environments.     

Betriebliches Identitätsmanagement

Enterprise Identity Management Systems (EIdMS) are an IT-based infrastructure that needs to be integrated in various business processes and related infrastructures. Assessment and preparation of decisions for the introduction need to take the costs, benefits, and the organizational settings into consideration. A variety of methods for the evaluation and decision support of new IT (e. g. EIdMS) are discussed in the literature – however, these are typically based on single dimensions (e. g. financial or technology aspects). This paper proposes a multidimensional decision support framework, based on the Balanced Scorecard concept. The presented approach introduces four perspectives and a related set of initial decision parameters to support decision making. The perspectives are (a) financial/monetary, (b) business processes, (c) supporting processes and (ICT) infrastructure and (d) information security, risks and compliance. Perspectives and adaptable sets of decision parameters also may serve as foundation for software-based decision support instruments.     

Insufficiency and excess of vitamin D activity (author's transl)

The most important attainments acquired over the past ten years dealing with vitamin D action molecules, their intakes, photosynthesis, main effects, activation, transport, storage, inactivation, activity at the cellular levels are recalled. They are at the basis of the classification of the clinical states arising from either a deficiency or an excess of the vitamin D activity. Six mechanisms may explain the lack of activity : intake or cutaneous to solar exposure deficiency, lack of digestive absorption, liver metabolism disturbances, renal 1-hydroxylase failure, cellular receptors dysfunction, oncogenic rickets. Excess of activity result from intoxication with massive doses of vitamin D, their active metabolites or synthetized analogs ; it may also result from their hypersensitivity either idiopathic or related to sarcoidosis, thyroid as well as adrenocortical insufficiency. These data constitute an introduction to research concerning the role of vitamin D at skin level, in chondrocytes, bone cells and to a clinicopharmacological exposure.     

PVF2 tranducers for Rayleigh waves

PVF2 thin-film transducers have been incorporated in a 8 MHz s.a.w. delay line. The flexibility of the transducer material will allow its use on curved as well as plane surfaces. Losses at frequencies typical in n.d.t. applications are in principle relatively low; it is for such tasks that the use of PVF2 s.a.w. transducers is seen as particularly appropriate.     

Experimental infection of pigs with the newly identified swine hepatitis E virus (swine HEV), but not with human strains of HEV

A novel virus of pigs, swine hepatitis E virus (swine HEV), was recently identified and shown to be antigenically and genetically related to human HEV. In the present study, we attempted to infect specific-pathogen-free (SPF) pigs experimentally with swine HEV or with human strains of HEV. Serum samples collected from naturally infected pigs were used as the source of swine HEV. Pigs inoculated intravenously with serum samples containing swine HEV seroconverted to anti-HEV 4 to 8 weeks postinoculation, and the virus spread to an uninoculated pig. Swine HEV was detected in nasal and rectal swab materials as early as 2 weeks postinoculation and for 4 to 8 weeks thereafter. Viremia appeared 4 to 6 weeks postinoculation and lasted 1 to 3 weeks. The inoculated pigs appeared clinically normal and serum liver enzymes were not significantly elevated. In contrast, pigs were not infected when inoculated intravenously with about 10(5) monkey infectious doses of one of two human strains of HEV (Sar-55 or Mex-14).