Nucleation and Growth of GaN on Sapphire by MBE

GaN was grown by molecular beam epitaxy in an effort to determine nucleation and growth conditions which lead to high quality, single-crystal films. Atomic force microscopy (AFM) was used to show that growth under Ga-rich conditions promotes the nucleation of films with large nucleation domains leading to a lower density of intrinsic defects related to domain boundaries. These conditions are also shown to promote a 2-D growth mode resulting in films with a high degree of nucleation domain coalescence and surface roughnesses below 2 nm. Addition of atomic hydrogen, using a thermally-cracked source, is shown to increase the growth rate of Ga-rich growths by a factor of two. The hydrogen appears to be altering the growth kinetics to increase the residence time of nitrogen atoms at the substrate surface. The addition of hydrogen seems to have no effect on the material characteristics as probed by Hall measurements and photoluminescence. In addition, the RF source used to generate active nitrogen species was characterized by means of mass spectroscopy and optical emission spectroscopy. Under normal operating conditions for GaN growth, the source was shown to convert about 5% of the total nitrogen input into neutral, nitrogen atoms and about 0.03% into nitrogen ions which may cause crystal damage during growth

Location-based Marketing: the academic framework

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Over the last several years one could observe revolution in location-based technologies and geospatial information. Location awareness of mobile devices resulted in development of Location-Based Services (LBS) that are realization of that revolution in the most personal and contextual way. The ability to reach consumers in the highly targeted manner based on spatio-temporal criteria, attracted marketers from the early beginning of LBS creating field called Location-Based Marketing. Today decreasing prices of smartphones and wireless internet, as well as integration of location-aware mobile solutions and social media is leading to new possibilities and opportunities. The academic and professional interests of the author made him noticed that although the industry has challenged a significant development, there is lack of publications that would put an academic framework on that progress. The research has fulfilled this gap by extensive investigation of the current state of the art of Location-Based Marketing and its foundations - Location Based Services. The dissertation provides academic framework by comprehensive analysis of the Location-Based Marketing from LBS and marketing perspective. Further the thesis is addressing the issue of significant discrepancy between theoretical concepts of measurable Location-Based Social Media data and the actual data than can be legally accessed and used for marketing analysis purposes by investigation a case study of Location-Based Social Network - Foursqaure and Location-Based Analytics platform VenueLabs

Processing Techniques of MOS Capacitors

Variations in both MOS capacitor structure and fabrication process were characterized using 1MHz C-V measurements. This involved processing MOS capacitors with and without backside oxide, and wet etching versus plasma ashing photoresist. The experimental results show large flatband shifts in wafers that were plasma ashed. ~ longer than expected anneal was utilized to reduce the C-V shifts caused by positive charge build-up in the oxide. The backside oxide did not grossly affect the capacitance measurements

Comparison of Effective Coverage Calculation Methods for Image Quality Assessment Databases

This article provides a comparison of a three methods that can be used for calculating effective coverage of image quality assessment database. The aim of this metric is to show how well the database is filled with variety of images. Foreach image in the database the Spatial Information (SI) and Colorfulness (CF) metric is calculated. The area of convex hull containing all the points on SI x CF plane is indication of total coverage of the database, but it does not show how efficiently this area is utilized. For this purpose an effective coverage was introduced. An analysis is performed for 16 databases - 13 publicaly available and 3 artificial created for the purpose of showing advantages of the effective coverage

¿Existen correlaciones entre los precios actuales de los cereales en Europa?

[EN] This paper evaluates the correlations between European cereal prices in up to 87 markets of 24 Member States. History and geography play a role: The highest correlations are observed between closely located internal markets of the “old” Union; prices are more correlated along transport routes, in particular rivers. We observe that 10 years after the Accession (8 in the case of Rumania and Bulgaria) we do not have a complete integration between the “old” and the “new” Member States. We advance several possible explana-tions: Weaker producers’ organisations, lack of storage facilities, less efficient transport facilities[ES] El artículo analiza las correlaciones de precios de los cereales, en 87 mercados de 24 Estados miembros de la Unión. La historia y la geografía desempeñan su papel: Por un lado, las mayores correla-ciones se observan entre los mercados de la “vieja” Europa y, por otro, también siguen las rutas de trasporte, en particular fluvial. Los Alpes siguen siendo una barrera. No tenemos aún una integración completa entre los «antiguos» y los «nuevos» Estados miembros. Adelantamos algunas explicaciones posibles, en par-ticular, la escasa organización de los productores y las deficiencias en las redes de transporte que todavía requieren inversionesBuczkowski, R.; García Azcárate, T. (2015). Are current EU cereal prices correlated?. Economía Agraria y Recursos Naturales - Agricultural and Resource Economics. 15(2):119-135. doi:10.7201/earn.2015.02.06SWORD11913515

Detection System for Scanning Electron Microscope

The kind of information and the quality of the backscattered electron (BSE) images depend upon numerous features of the detector. Therefore, various types of detectors should be used simultaneously to obtain as much of information as possible. The detection system presented here contains a large area semiconductor detector and a BSE to secondary electrons (SE) converter system. These two different kinds of detectors give different BSE images. After subtracting the signal of a semiconductor detector from that of a converter system, an image with good topography and reduced material contrast can be achieved

The Effect of Urbanization on Ant Abundance and Diversity: A Temporal Examination of Factors Affecting Biodiversity.

Numerous studies have examined the effect of urbanization on species richness and most studies implicate urbanization as the major cause of biodiversity loss. However, no study has identified an explicit connection between urbanization and biodiversity loss as the impact of urbanization is typically inferred indirectly by comparing species diversity along urban-rural gradients at a single time point. A different approach is to focus on the temporal rather than the spatial aspect and perform “before and after” studies where species diversity is cataloged over time in the same sites. The current study examined changes in ant abundance and diversity associated with the conversion of natural habitats into urban habitats. Ant abundance and diversity were tracked in forested sites that became urbanized through construction and were examined at 3 time points - before, during, and after construction. On average, 4.3±1.2 unique species were detected in undisturbed plots prior to construction. Ant diversity decreased to 0.7±0.8 species in plots undergoing construction and 1.5±1.1 species in plots 1 year after construction was completed. With regard to species richness, urbanization resulted in the permanent loss of 17 of the 20 species initially present in the study plots. Recovery was slow and only 3 species were present right after construction was completed and 4 species were present 1 year after construction was completed. The second objective examined ant fauna recovery in developed residential lots based on time since construction, neighboring habitat quality, pesticide inputs, and the presence of invasive ants. Ant diversity was positively correlated with factors that promoted ecological recovery and negatively correlated with factors that promoted ecological degradation. Taken together, these results address a critical gap in our knowledge by characterizing the short- and long-term the effects of urbanization on the loss of ant biodiversity

Signal Mixing Technique for Backscattered Electrons in the Scanning Electron Microscope

Signal mixing technique using asymetrically placed backscattered electron detectors in a scanning electron microscope is presented in this paper. Two types of detectors have been used: a low-take off angle ring scintillation detector (placed around the specimen) and a wide-angle semiconductor detector (placed above the specimen). It has been shown that the discussed configuration gives good real topography in all directions on the specimen surface and also reduces significantly the pseudo-topography effect of flat grain boundaries