Sixty GHz IMPATT diode development

The objective of this program is to develop 60 GHz GaAs IMPATT Diodes suitable for communications applications. The performance goal of the 60 GHz IMPATT is 1W CW output power with a conversion efficiency of 15 percent and 10 year life time. During the course of the program, double drift (DD) GaAs IMPATT Diodes have been developed resulting in the state of the art performance at V band frequencies. A CW output power of 1.12 W was demonstrated at 51.9 GHz with 9.7 percent efficiency. The best conversion efficiency achieved was 15.3 percent. V band DD GaAs IMPATTs were developed using both small signal and large signal analyses. GaAs wafers of DD flat, DD hybrid, and DD Read profiles using molecular beam epitaxy (MBE) were developed with excellent doping profile control. Wafer evaluation was routinely made by the capacitance versus voltage (C-V) measurement. Ion mass spectrometry (SIMS) analysis was also used for more detailed profile evaluation

Improving the Representation and Conversion of Mathematical Formulae by Considering their Textual Context

Mathematical formulae represent complex semantic information in a concise form. Especially in Science, Technology, Engineering, and Mathematics, mathematical formulae are crucial to communicate information, e.g., in scientific papers, and to perform computations using computer algebra systems. Enabling computers to access the information encoded in mathematical formulae requires machine-readable formats that can represent both the presentation and content, i.e., the semantics, of formulae. Exchanging such information between systems additionally requires conversion methods for mathematical representation formats. We analyze how the semantic enrichment of formulae improves the format conversion process and show that considering the textual context of formulae reduces the error rate of such conversions. Our main contributions are: (1) providing an openly available benchmark dataset for the mathematical format conversion task consisting of a newly created test collection, an extensive, manually curated gold standard and task-specific evaluation metrics; (2) performing a quantitative evaluation of state-of-the-art tools for mathematical format conversions; (3) presenting a new approach that considers the textual context of formulae to reduce the error rate for mathematical format conversions. Our benchmark dataset facilitates future research on mathematical format conversions as well as research on many problems in mathematical information retrieval. Because we annotated and linked all components of formulae, e.g., identifiers, operators and other entities, to Wikidata entries, the gold standard can, for instance, be used to train methods for formula concept discovery and recognition. Such methods can then be applied to improve mathematical information retrieval systems, e.g., for semantic formula search, recommendation of mathematical content, or detection of mathematical plagiarism.Comment: 10 pages, 4 figure

A Survey on Retrieval of Mathematical Knowledge

We present a short survey of the literature on indexing and retrieval of mathematical knowledge, with pointers to 72 papers and tentative taxonomies of both retrieval problems and recurring techniques.Comment: CICM 2015, 20 page

Semantic Tagging of Mathematical Expressions

Semantic tagging of mathematical expressions (STME) gives semantic meanings to tokens in mathematical expressions. In this work, we propose a novel STME approach that relies on neither text along with expressions, nor labelled train-ing data. Instead, our method only requires a mathemati-cal grammar set. We point out that, besides the grammar of mathematics, the special property of variables and user habits of writing expressions help us understand the im-plicit intents of the user. We build a system that considers both restrictions from the grammar and variable properties, and then apply an unsupervised method to our probabilis-tic model to learn the user habits. To evaluate our system, we build large-scale training and test datasets automatically from a public math forum. The results demonstrate the significant improvement of our method, compared to the maximum-frequency baseline. We also create statistics to reveal the properties of mathematics language

Nanofiltration of hormone mimicking trace organic contaminants

The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore size were used in laboratory-scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound ¾ nonylphenol, tert-butyl phenol, or bisphenol A. Retention of the compounds was determined at various solution chemistries, namely aqueous solution pH, ionic strength, and presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking compounds appears similar to that of natural hormones as reported in our previous work. While the solution pH can dramatically influence the retention of hormone mimicking compounds by a loose NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in the presence of natural organic matter in the feed solution, ionic strength appears to play a significant role in solute-solute and solute-membrane interactions, resulting in increased retention due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic strength

Insight from the draft genome of Dietzia cinnamea P4 reveals mechanisms of survival in complex tropical soil habitats and biotechnology potential

The draft genome of Dietzia cinnamea strain P4 was determined using pyrosequencing. In total, 428 supercontigs were obtained and analyzed. We here describe and interpret the main features of the draft genome. The genome contained a total of 3,555,295 bp, arranged in a single replicon with an average G+C percentage of 70.9%. It revealed the presence of complete pathways for basically all central metabolic routes. Also present were complete sets of genes for the glyoxalate and reductive carboxylate cycles. Autotrophic growth was suggested to occur by the presence of genes for aerobic CO oxidation, formate/formaldehyde oxidation, the reverse tricarboxylic acid cycle and the 3-hydropropionate cycle for CO2 fixation. Secondary metabolism was evidenced by the presence of genes for the biosynthesis of terpene compounds, frenolicin, nanaomycin and avilamycin A antibiotics. Furthermore, a probable role in azinomycin B synthesis, an important product with antitumor activity, was indicated. The complete alk operon for the degradation of n-alkanes was found to be present, as were clusters of genes for biphenyl ring dihydroxylation. This study brings new insights in the genetics and physiology of D. cinnamea P4, which is useful in biotechnology and bioremediation

Greenland ice sheet surface mass loss: recent developments in observation and modeling

Surface processes currently dominate Greenland ice sheet (GrIS) mass loss. We review recent developments in the observation and modelling of GrIS surface mass balance (SMB), published after the July 2012 deadline for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). Since IPCC AR5 our understanding of GrIS SMB has further improved, but new observational and model studies have also revealed that temporal and spatial variability of many processes are still poorly quantified and understood, e.g. bio-albedo, the formation of ice lenses and their impact on lateral meltwater transport, heterogeneous vertical meltwater transport (‘piping’), the impact of atmospheric circulation changes and mixed-phase clouds on the surface energy balance and the magnitude of turbulent heat exchange over rough ice surfaces. As a result, these processes are only schematically or not at all included in models that are currently used to assess and predict future GrIS surface mass loss

In situ functionalization of a cellulosic-based activated carbon with magnetic iron oxides for the removal of carbamazepine from wastewater

The main goal of this work was to produce an easily recoverable waste-based magnetic activated carbon (MAC) for an efficient removal of the antiepileptic pharmaceutical carbamazepine (CBZ) from wastewater. For this purpose, the synthesis procedure was optimized and a material (MAC4) providing immediate recuperation from solution, remarkable adsorptive performance and relevant properties (specific surface area of 551 m2 g-1 and saturation magnetization of 39.84 emu g-1) was selected for further CBZ kinetic and equilibrium adsorption studies. MAC4 presented fast CBZ adsorption rates and short equilibrium times (< 30-45 min) in both ultrapure water and wastewater. Equilibrium studies showed that MAC4 attained maximum adsorption capacities (qm) of 68 ± 4 mg g-1 in ultrapure water and 60 ± 3 mg g-1 in wastewater, suggesting no significant interference of the aqueous matrix in the adsorption process. Overall, this work provides evidence of potential application of a waste-based MAC in the tertiary treatment of wastewaters.publishe

Northern Eurasia Future Initiative (NEFI): facing the challenges and pathways of global change in the twenty-first century

© 2017, The Author(s). During the past several decades, the Earth system has changed significantly, especially across Northern Eurasia. Changes in the socio-economic conditions of the larger countries in the region have also resulted in a variety of regional environmental changes that can have global consequences. The Northern Eurasia Future Initiative (NEFI) has been designed as an essential continuation of the Northern Eurasia Earth Science Partnership Initiative (NEESPI), which was launched in 2004. NEESPI sought to elucidate all aspects of ongoing environmental change, to inform societies and, thus, to better prepare societies for future developments. A key principle of NEFI is that these developments must now be secured through science-based strategies co-designed with regional decision-makers to lead their societies to prosperity in the face of environmental and institutional challenges. NEESPI scientific research, data, and models have created a solid knowledge base to support the NEFI program. This paper presents the NEFI research vision consensus based on that knowledge. It provides the reader with samples of recent accomplishments in regional studies and formulates new NEFI science questions. To address these questions, nine research foci are identified and their selections are briefly justified. These foci include warming of the Arctic; changing frequency, pattern, and intensity of extreme and inclement environmental conditions; retreat of the cryosphere; changes in terrestrial water cycles; changes in the biosphere; pressures on land use; changes in infrastructure; societal actions in response to environmental change; and quantification of Northern Eurasia’s role in the global Earth system. Powerful feedbacks between the Earth and human systems in Northern Eurasia (e.g., mega-fires, droughts, depletion of the cryosphere essential for water supply, retreat of sea ice) result from past and current human activities (e.g., large-scale water withdrawals, land use, and governance change) and potentially restrict or provide new opportunities for future human activities. Therefore, we propose that integrated assessment models are needed as the final stage of global change assessment. The overarching goal of this NEFI modeling effort will enable evaluation of economic decisions in response to changing environmental conditions and justification of mitigation and adaptation efforts