Business Models for Electronic Commerce - Analysis of Grocery Retailing Industry

Electronic commerce can dramatically alter the current delivery and sales channels, as well as value chains in many industries. Accordingly, consumers will change or supplement their channel preferences with increasing amount of electronic services available. This study focuses on the different types of business models used in the grocery retailing industry, to serve consumers. The empirical part of he analysis is based on a longitudinal analysis of existing EGS’ in 1998 and 1999 in Europe, North America and Pacific Asia. The analysis shows that the majority of the electronic grocery shops are extensions of existing physical stores. There are, however, some signs of interesting new business strategies. These strategies are compared to the theoretical alternatives proposed by the model of Customer Channels and conclusions are drawn regarding the development of electronic commerce in grocery industry

Vacancy-Impurity Complexes in Highly Sb-Doped Si Grown by Molecular Beam Epitaxy

Positron annihilation measurements, supported by first-principles electron-structure calculations, identify vacancies and vacancy clusters decorated by 1–2 dopant impurities in highly Sb-doped Si. The concentration of vacancy defects increases with Sb doping and contributes significantly to the electrical compensation. Annealings at low temperatures of 400–500 K convert the defects to larger complexes where the open volume is neighbored by 2–3 Sb atoms. This behavior is attributed to the migration of vacancy-Sb pairs and demonstrates at atomic level the metastability of the material grown by epitaxy at low temperature.Peer reviewe

Evaluation of a smartphone app for forest sample plot measurements

We evaluated a smartphone app (TRESTIMA(TM)) for forest sample plot measurements. The app interprets imagery collected from the sample plots using the camera in the smartphone and then estimates forest inventory attributes, including species-specific basal areas (G) as well as the diameter (D-gM) and height (H-gM) of basal area median trees. The estimates from the smartphone app were compared to forest inventory attributes derived from tree-wise measurements using calipers and a Vertex height measurement device. The data consist of 2169 measured trees from 25 sample plots (32 m x 32 m), dominated by Scots pine and Norway spruce from southern Finland. The root-mean-square errors (RMSEs) in the basal area varied from 19.7% to 29.3% and the biases from 11.4% to 18.4% depending on the number of images per sample plot and image shooting location. D-gM measurement bias varied from -1.4% to 3.1% and RMSE from 5.2% to 11.6% depending on the tree species. Respectively, H-gM bias varied from 5.0% to 8.3% and RMSE 10.0% to 13.6%. In general, four images captured toward the center of the plot provided more accurate results than four images captured away from the plot center. Increasing the number of captured images per plot to the analyses yielded only marginal improvement to the results.Peer reviewe

Zinc vacancies in the heteroepitaxy of ZnO on sapphire: Influence of the substrate orientation and layer thickness

Positron annihilation spectroscopy has been used to study the vacancy-type defects produced in films grown by metalorganic chemical vapor deposition on different sapphire orientations. Zn vacancies are the defects controlling the positron annihilation spectra at room temperature. Close to the interface (<500nm) their concentration depends on the surface plane of sapphire over which the ZnO film has been grown. The Zn vacancy content in the film decreases with thickness, and above 1μm it is independent of the substrate orientation.Peer reviewe

Correlation between Zn vacancies and photoluminescence emission in ZnO films.

Photoluminescence and positron annihilation spectroscopy have been used to characterize and identify vacancy-type defects produced in ZnO films grown on sapphire by metal-organic chemical-vapor deposition. The photoluminescence of the samples in the near band edge region has been studied, paying particular attention to the emission at 370.5 nm (3.346 eV). This emission has been correlated to the concentration of Zn vacancies in the films, which has been determined by positron annihilation [email protected] [email protected]

Target chamber for a slow positron beam: optimization of count rate and minimization of backscattering effects

Abstract Positrons, which scatter back from the target and annihilate in chamber walls near the detectors, may cause a significant error in annihilation parameters. We have constructed a new UHV target chamber for slow positron beam studies. In our design special care has been taken to reduce the effect of backscattered positrons. Detector wells are designed for two-detector coincidence measurements and they are situated on both sides of the target. The distance of the wells from the target can be adjusted by simple manipulators. This enables optimization regarding the count rate and the rate of backscattered positrons hitting the detector wells. The magnetic field in front of the target is increased by permanent magnets situated behind the target. The increased magnetic field guides the backscattered positrons effectively away from the detectors. The increased magnetic field also focuses the beam spot strongly.

Negative density-distribution relationship in butterflies

Peer reviewe

Vacancy-Impurity Complexes in Highly Sb-Doped Si Grown by Molecular Beam Epitaxy

Positron annihilation measurements, supported by first-principles electron-structure calculations, identify vacancies and vacancy clusters decorated by 1-2 dopant impurities in highly Sb-doped Si. The concentration of vacancy defects increases with Sb doping and contributes significantly to the electrical compensation. Annealings at low temperatures of 400 -500 K convert the defects to larger complexes where the open volume is neighbored by 2 -3 Sb atoms. This behavior is attributed to the migration of vacancy-Sb pairs and demonstrates at atomic level the metastability of the material grown by epitaxy at low temperature. DOI: 10.1103/PhysRevLett.94.165501 PACS numbers: 61.72.-y, 61.82.Fk, 78.70.Bj The interest in highly doped Si is fundamentally related to the miniaturization of field-effect transistors, where increased doping is needed to maintain a sufficient conductance of the source and drain regions The molecular beam epitaxy (MBE) growth at low temperature ( &lt; 600 K) can be applied to achieve metastable doping and free electron concentrations, which become compensated only at 10 21 cm ÿ3 In this work we apply positron annihilation spectroscopy to study vacancies formed in the low-temperature MBE growth of highly Sb-doped Si. Positrons get trapped at open-volume defects. The measured annihilation photons carry information on the electron momentum density, which can be utilized to identify the size of the open volume of the defect and the neighboring dopant atoms. Our results show that the MBE growth creates vacancies and vacancy clusters, which are neighbored by 1-2 Sb atoms. The vacancy concentrations are relevant for the compensation of the Sb doping. We also show that the low-temperature MBE Si is atomically metastable, and annealings at low temperatures of 400 -500 K lead to clustering of vacancies and dopant impurities. We studied Si(100) layers grown by MBE on the Si substrate at 550 K We used a low-energy positron beam to measure the Doppler broadened energy spectrum of the annihilation radiation. The shape of the spectrum was described with conventional S and W parameter