1,721,033 research outputs found
Simulating Spatial Distributions, Variability and Uncertainty of Soil Arsenic by Geostatistical Simulations in Geographic Information Systems
No full textVLSI compatible parallel fabrication and characterisation of down-scaled multi-configuration Silicon quantum dot devices
No full textElectron spins in semiconductor quantum dots (QDs) have been increasingly shown in recent years to be a promising platform for realising the qubit – the basic unit of information in quantum computing. A crucial advantage of silicon QDs over alternative platforms is the potential for scalability in a quantum system to contain large numbers of qubits. Electron spins in Si-based QDs also have the benefit of a much longer spin coherence time relative to their extensively researched GaAs based counter parts – a prerequisite which gives the essential time needed for successful quantum gate operations and quantum computations.In this work, we propose and realise the first very large scale integration (VLSI) compatible process capable of fabricating scalable repeatable QD systems in parallel using silicon on insulator (SOI) technology. 3D finite element method (FEM) capacitance and single electron circuit simulations are first utilised to demonstrate the suitability of our double quantum dot (DQD) design dimensions in supporting single electron operation and detection. Here, we also present a new method of detection for single electron turnstile operations which makes use of the periodicity present in the charge stability diagram of a DQD.Through process optimisation, we fabricate 144 high density lithographically defined Si DQDs for the first time in parallel with 80% of the fabricated devices having dimensional variations of less than 5 nm. The novel use of hydrogen silsesquioxane (HSQ) resist with electron beam lithography (EBL) enabled the realisation of lithographically defined reproducible QD dimensions of an average of 51 nm with a standard deviation of 3.4 nm. Combined with an optimised thermal oxidation process, we demonstrate the precise fabrication of different QDs ranging from just 10.6 nm to over 20 nm. These are the smallest lithographically defined high density intrinsic SOI based QDs achieved to date. In addition, we demonstrate the flexibility of our fabrication process in its ability to realise a wide variety of complex device designs repeatedly. A key advantage of our process is its ability to support the scalable fabrication of QD devices without significantly affecting fabrication turnover time.Repeatable characteristic QD Coulomb oscillations and Coulomb diamonds signifying single electron tunnelling through our system are observed in electrical characteristics. Here we achieve precise independent simultaneous control of different QD’s single electron occupation as well as demonstrate evidence suggesting charge detection between QD channels. The unmatched level of clarity observed within Coulomb blockade diamond characteristics at 4.2K enables observations of line splitting of our QD’s excited states at this temperature, and readout of the spin orientation of sequential single electrons filling the QD. Through this spin readout, we gained an idea of the number of electrons stored on the QD and in turn, our ability to control the QD with precision down to the single electron limit.Statistically, we realise a parallel fabrication yield of 69% of devices demonstrating the ability to switch on and off repeatedly at 4K cryogenic temperatures with no leakage and sufficient channel resistances for single electron turnstile operations. This is the highest achieved yield observed to date for fabrication of intrinsic SOI based QD systems
Comparison of sequential Gaussian simulation, simulated annealing simulation and kriging methods for characterizing soil lead
No full textMultivariate Analysis of the soil heavy metal pollution and Landscape patterns analysis in Changhua County in Taiwan
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dynamics of changes in micronucleus frequencies in subjects post cessation of chronic low-dose radiation exposure
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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