Depth-integrated primary production in the eastern tropical and subtropical North Atlantic basin from ocean colour imagery

Existing satellite numerical models and data interpolation methods were used to evaluate the scales of variation in the vertical distribution of the phytoplankton biomass and the daily rate of primary production within the subtropical and tropical NE Atlantic Ocean (5-40 N; 6-30 W). The choice of this area was dictated principally by its economical importance, as it represents a large fishing ground due to upwelling activities along the coast of Morocco and Mauritania. After geographical partition of the area of study into 'bio-geochemical provinces' based on bathymetry and surface circulation, up to 300 satellite scenes obtained from the defunct Coastal Zone Color Scanner (CZCS) and covering the full year 1983 were processed into maps of surface chlorophyll and were further analysed into integrated primary production. Analyses of satellite data included a specific method to account for the sensitivity loss of the sensor during the studied period. The results of the productivity model are presented in terms of seasonal variations in the daily and annual photosynthetic carbon production in the various provinces and their contribution to the productivity of the overall study area. A total of 0.82 GtC y-1 was computed for the subtropical and tropical NE Atlantic. One third of this is produced within the coastal zone although it accounts for only 14% of the total area.     

Investitionsgüterhersteller als Anbieter industrieller Lösungen – Bestandsaufnahme des Wandels anhand einer Umfrage

The article is dedicated to the empirical exploration of solution providers in the German capital goods industry. A model – consisting of six principles and success factors for solution management – is used to draw conclusions on the relevance and the need for action to manage the transition towards being a solution provider. The answers from 99 medium-sized companies reveal the following results: 1.) The solution concept offers the opportunity to gain competitive advantage 2.) The potential of providing solutions has been recognised, yet the implementation is lagging behind 3.) A consistent solution management process is a prerequisite for success 4.) Appropriate methods and tools are required along the whole process.     

Role of majority and minority carrier barriers silicon/organic hybrid heterojunction solar cells

A hybrid approach to solar cells is demonstrated in which a silicon p-n junction, used in conventional silicon-based photovoltaics, is replaced by a room-temperature fabricated silicon/organic heterojunction. The unique advantage of silicon/organic heterojunction is that it exploits the cost advantage of organic semiconductors and the performance advantages of silicon to enable potentially low-cost, efficient solar cells.     

Effect of Sediment pH on Resuspension of Kaolinite Sediments

The resuspension of contaminated cohesive sediments can impact water quality by mobilizing sediment particles and adsorbed contaminants. Changes in psysicochemical and electrochemical environments, around resuspended sediment particles, may cause some contaminants to desorb into the water column. The contribution of contaminated sediments to degradation of water quality depends on an estimate of sediment resuspension rates. In this study, the resuspension of Georgia kaolinite sediments under varying pH conditions was investigated in laboratory flume experiments. Because the edge charge of kaolinite particles is pH dependent, kaolinite particles exhibit different modes of particle associations under varying pH conditions. The paper characterizes these particle associations and relates them to the resuspension of kaolinite sediments for varying pH values. Variations in sediment water content, changes from a stratified to a uniform sediment bed, changes in rheological properties, and variations in the electrophoretic mobility of kaolinite particles were all indicative of the changes in particle associations that resulted from changes in sediment pH. The critical shear stress and the erosion rate coefficient were evaluated for varying pH values and explained by particle associations. A rheometer was used to measure rheological properties of the settled sediment bed; the measured yield stresses had a direct correlation with critical shear stresses.     

A generic structure-from-motion framework

We introduce a generic structure-from-motion approach based on a previously introduced, highly general imaging model, where cameras are modeled as possibly unconstrained sets of projection rays. This allows to describe most existing camera types including pinhole cameras, sensors with radial or more general distortions, catadioptric cameras (central or non-central), etc. We introduce a structure-from-motion approach for this general imaging model, that allows to reconstruct scenes from calibrated images, possibly taken by cameras of different types (cross-camera scenarios). Structure-from-motion is naturally handled via camera independent ray intersection problems, solved via linear or simple polynomial equations. We also propose two approaches for obtaining optimal solutions using bundle adjustment, where camera motion, calibration and 3D point coordinates are refined simultaneously. The proposed methods are evaluated via experiments on two cross-camera scenarios—a pinhole used together with an omni-directional camera and a stereo system used with an omni-directional camera.     

Sparse Approximation and the Pursuit of Meaningful Signal Models With Interference Adaptation

In the pursuit of a sparse signal model, mismatches between the signal and the dictionary, as well as atoms poorly selected by the decomposition process, can diminish the efficiency and meaningfulness of the resulting representation. These problems increase the number of atoms needed to model a signal for a given error, and they obscure the relationships between signal content and the elements of the model. To increase the efficiency and meaningfulness of a signal model built by an iterative descent pursuit, such as matching pursuit (MP), we propose integrating into its atom selection criterion a measure of interference between an atom and the model. We define interference and illustrate how it describes the contribution of an atom to modeling a signal. We show that for any nontrivial signal, the convergent model created by MP must have as much destructive as constructive interference, i.e., MP cannot avoid correction in the signal model. This is not necessarily a shortcoming of orthogonal variants of MP, such as orthogonal MP (OMP). We derive interference-adaptive iterative descent pursuits and show how these can build signal models that better fit the signal locally, and reduce the corrections made in a signal model. Compared with MP and its orthogonal variants, our experimental results not only show an increase in model efficiency, but also a clearer correspondence between the signal and the atoms of a representation.      

OCEANcode: The complete set of algorithms and models for the level_2 processing of European CZCS historical data

A complete set of algorithms and models for the level_2 processing of the European CZCS historical data was integrated in the OCEANcode software package. The OCEANcode allows the calibration of the sensor-recorded signal taking into account the instrument sensitivity loss; the correction of the calibrated signal for atmospheric contamination and derive sub-surface reflectances; and then the estimation of the concentration of water constituents. The atmospheric correction is performed on the basis of a reflectance-model-based algorithm. The Rayleigh correction is applied consistently for all water pixels, using a multiple scattering approach, and introducing atmospheric pressure and Ozone concentration data in the computation. The marine aerosol correction uses a pixel-by-pixel iterative procedure, allowing successive estimates of both the marine reflectance in the red spectral region (670nm) and the Angstrom exponent, which links simple wavelengths ratios to reflectance ratios. For case 1 waters, the optical properties of which are essentially dominated by planktonic pigments, the interrelations between marine reflectances and reflectance ratios at various wavelengths are derived from modelled calculations. For identified case 2 waters, where water constituents other than planktonic pigments (i.e. dissolved organics and suspended sediments) dominate the water optical properties, the evaluation of marine reflectances is approximated by means of interpolated Angstrom exponent values computed over case 1 water pixels and of empirical relationships derived from in situ measurements. The computation of chlorophyll-like pigments is performed with algorithms based on blue/green (443-550nm) reflectance ratios, for lower pigment concentration, or on green/green (520-550nm) reflectance ratios, for higher pigment concentration. As for the case of atmospheric corrections, the inter-relations between pigment concentration and reflectance ratios are model-derived for case 1 waters, and empirically determined for case 2 waters.     

Magnetic Nanoparticle Chains in Gelatin Ferrogels: Bioinspiration from Magnetotactic Bacteria

Inspired by chains of ferrimagnetic nanocrystals (NCs) in magnetotactic bacteria (MTB), the synthesis and detailed characterization of ferrimagnetic magnetite NC chain‐like assemblies is reported. An easy green synthesis route in a thermoreversible gelatin hydrogel matrix is used. The structure of these magnetite chains prepared with and without gelatin is characterized by means of transmission electron microscopy, including electron tomography (ET). These structures indeed bear resemblance to the magnetite assemblies found in MTB, known for their mechanical flexibility and outstanding magnetic properties and known to crystallographically align their magnetite NCs along the strongest <111> magnetization easy axis. Using electron holography (EH) and angular dependent magnetic measurements, the magnetic interaction between the NCs and the generation of a magnetically anisotropic material can be shown. The electro‐ and magnetostatic modeling demonstrates that in order to precisely determine the magnetization (by means of EH) inside chain‐like NCs assemblies, their exact shape, arrangement and stray‐fields have to be considered (ideally obtained using ET).     

Optical receiver IC for CD/DVD/blue-laser application

In this paper, an optoelectronic receiver IC for CD, DVD, and Blue-Laser optical data storage applications is presented. The IC was developed in a 0.5-/spl mu/m BiCMOS technology with integrated PIN photodiodes. It includes a new architecture of high-speed and low-noise variable gain transimpedance amplifiers witch current preamplifier input. The amplifier transimpedance gain is programmable over a gain range of 130 /spl Omega/ to 270 k/spl Omega/ by a serial interface. The amplifier small-signal bandwidth is 260 MHz for the highest gain, which gives a gain-bandwidth product of 70 THz/spl Omega/ and a sensitivity improvement by a factor of 2 compared to published OEICs. The amplifiers support a special write/clip mode which realizes a nonlinear gain reduction for high input signals. The output voltage buffers are 130-/spl Omega/ impedance matched for optimized data transmission over a flex cable. The impedance is generated by active-impedance synthesis to increase the output dynamic range.     

Integrated amorphous and polycrystalline silicon thin-filmtransistors in a single silicon layer

Using a masked hydrogen plasma treatment to spatially control the crystallization of amorphous silicon to polycrystalline silicon in desired areas, amorphous and polycrystalline silicon thin-film transistors (TFTs) with good performance have been integrated in a single film of silicon without laser processing. Both transistors are top gate and shared all process steps. The polycrystalline silicon transistors have an electron mobility in the linear regime of ~15 cm²/Vs, the amorphous silicon transistors have a linear mobility of ~0.7 cm²/Vs and both have an ON/OFF current ratios of >10⁵. Rehydrogenation of amorphous silicon after the 600°C crystallization anneal using another hydrogen plasma is the critical process step for the amorphous silicon transistor performance. The rehydrogenation power, time, and reactor history are the crucial details that are discussed in this paper