An Automatic Level Set Based Liver Segmentation from MRI Data Sets

A fast and accurate liver segmentation method is a challenging work in medical image analysis area. Liver segmentation is an important process for computer-assisted diagnosis, pre-evaluation of liver transplantation and therapy planning of liver tumors. There are several advantages of magnetic resonance imaging such as free form ionizing radiation and good contrast visualization of soft tissue. Also, innovations in recent technology and image acquisition techniques have made magnetic resonance imaging a major tool in modern medicine. However, the use of magnetic resonance images for liver segmentation has been slow when we compare applications with the central nervous systems and musculoskeletal. The reasons are irregular shape, size and position of the liver, contrast agent effects and similarities of the gray values of neighbor organs. Therefore, in this study, we present a fully automatic liver segmentation method by using an approximation of the level set based contour evolution from T2 weighted magnetic resonance data sets. The method avoids solving partial differential equations and applies only integer operations with a two-cycle segmentation algorithm. The efficiency of the proposed approach is achieved by applying the algorithm to all slices with a constant number of iteration and performing the contour evolution without any user defined initial contour. The obtained results are evaluated with four different similarity measures and they show that the automatic segmentation approach gives successful results

Fusion System and group actions with abelian isotropy subgroups

Cataloged from PDF version of article.We prove that if a finite group G acts smoothly on a manifold M such that all the isotropy subgroups are abelian groups with rank ≤ k, then G acts freely and smoothly on M × double struk S signn1 ×... × double struk S signnk for some positive integers n1, ..., nk. We construct these actions using a recursive method, introduced in an earlier paper, that involves abstract fusion systems on finite groups. As another application of this method, we prove that every finite solvable group acts freely and smoothly on some product of spheres, with trivial action on homology. Copyright © Edinburgh Mathematical Society 2013

Aspect acquisition in Russian as the weaker language: evidence from a Turkish-Russian child

Aims and objectives/purpose/research questions: This study aims to contribute to the discussion about the weaker language development by examining the effect of restricted input and use on the acquisition of the morphological category of aspect in Russian by a Turkish–Russian bilingual child in a Turkish-dominant environment. The main goal the study pursues is to investigate whether the reduced input and restricted use of Russian, mainly through communication with a Russian-speaking mother, is still sufficient for monolingual-like acquisition of Russian aspect. Design/methodology/approach: This study is a longitudinal case study. Data and analysis: The main source of data collection is video and audio recordings. Twenty-five recordings are available. They cover the period of between two years and 11 months (2;11) and 4;0. First, the data is examined in terms of the availability of perfective and imperfective forms and meanings they (these forms) express in the Russian language. Then, we look into whether the data of the bilingual child is marked with deviations from the monolingual Russian data in terms of error rates and patterns. Findings/conclusions: The findings of the study suggest that despite the reduced input, the acquisition of Russian aspect in the Turkish-dominant environment follows the same pattern as a monolingual acquisition does. Originality, and significance/implications: The study contributes to the discussion about the weaker language development in bilingual contexts and adds to the growing body of research looking at the development of a particular language in a variety of different contexts

Examining possible sources of L2 divergence at the pragmatics interface: Turkish accusative in the end-state grammar of L1 Russian and L1 English users of L2 Turkish

The Interface Hypothesis (IH) postulates that interface structures are potentially vulnerable to incomplete acquisition in the end-state L2. Two plausible explanations have been suggested as possible causes of the L2 divergence at the interface: (1) the interaction between two competing grammatical systems, and (2) differences between monolinguals and bilinguals in integrating information from different domains in L2. This study aims to contribute to a deeper understanding of the interface phenomenon and to examine the extent to which L1 interference might account for L2 divergence at the interface. To this end, the study examines the use of Turkish accusative case (AC) in the end-state L2 grammar of L1 Russian and L1 English advanced users of L2 Turkish. The findings provide additional evidence for the IH and suggest that L2 divergence at the interface is likely to reflect more differences between monolinguals and bilinguals in integrating information from different domains rather than L1 interference

Controlling the charge transfer flow at the graphene/pyrene-nitrilotriacetic acid interface

The fabrication of highly efficient bio-organic nanoelectronic devices is still a challenge due to the difficulty in interfacing the biomolecular component to the organic counterparts. One of the ways to overcome this bottleneck is to add a self-assembled monolayer (SAM) in between the electrode and the biological material. The addition of a pyrene-nitrilotriacetic acid layer to a graphene metal electrode enhances the charge transfer within the device. Our theoretical calculations and electrochemical results show that the formation of a pyrene-nitrilotriacetic acid SAM enforces a direct electron transfer from graphene to the SAM, while the addition of the Ni2+ cation and imidazole reverses the charge transfer direction, allowing an atomic control of the electron flow, which is essential for a true working device. © 2018 The Royal Society of Chemistry

Interfaces in the returnees' heritage language: Is the complete (re-)activation possible?

Aims and objectives/purpose/research questions: The aim of this study is to examine whether the complete (re-)activation of interface domains in the heritage language (HL) is possible or whether interfaces are likely to preserve features typical for the HL even after many years of residing in the country of origin. Design/methodology/approach: We present the group analysis of direct object marking in Turkish, which is a morphology-syntax-pragmatics interface, of Turkish-German returnees, who returned to Turkey after puberty and have been residing in the country for a minimum of 10 and a maximum of 34 years, and compare them with the control group consisting of Turkish speakers who have been living in Turkey all their lives. Data and analysis: The data were collected using a narrative task, a completion task and a grammaticality judgement task, and analysed both quantitatively and qualitatively. Findings/conclusions: The analysis of the narrative task revealed that the returnee participants used case-marking on direct objects productively depending on the discourse and syntactic position of the direct object in their heritage Turkish. However, their performance on the completion and grammaticality judgement tasks diverged from those of the control group. These findings can be considered as a piece of evidence that interface domains stay obstinate to complete (re-)activation and may preserve features typical for the HL many years after the return to the country of origin. Originality: The study suggests relevance of the Interface Hypothesis to the process of HL (re-)activation. Significance/implications: The study contributes to the research on the HL development of returnees after their return to the country of origin

100 GHz resonant cavity enhanced Schottky photodiodes

Cataloged from PDF version of article.Resonant cavity enhanced (RCE) photodiodes are promising candidates for applications in optical communications and interconnects where ultrafast high-efficiency detection is desirable. We have designed and fabricated RCE Schottky photodiodes in the (Al, In) GaAs material system for 900-nm wavelength. The observed temporal response with 10-ps pulsewidth was limited by the measurement setup and a conservative estimation of the bandwidth corresponds to more than 100 GHz. A direct comparison of RCE versus conventional detector performance was performed by high speed measurements under optical excitation at resonant wavelength (895 nm) and at 840 nm where the device functions as a single-pass conventional photodiode. A more than two-fold bandwidth enhancement with the RCE detection scheme was demonstrated

Design and Optimization of High-Speed Resonant Cavity Enhanced Schottky Photodiodes

Cataloged from PDF version of article.Resonant cavity enhanced (RCE) photodiodes (PD’s) are promising candidates for applications in optical communications and interconnects where high-speed high-efficiency photodetection is desirable. In RCE structures, the electrical properties of the photodetector remain mostly unchanged; however, the presence of the microcavity causes wavelength selectivity accompanied by a drastic increase of the optical field at the resonant wavelengths. The enhanced optical field allows to maintain a high efficiency for faster transit-time limited PD’s with thinner absorption regions. The combination of an RCE detection scheme with Schottky PD’s allows for the fabrication of high-performance photodetectors with relatively simple material structures and fabrication processes. In top-illuminated RCE Schottky PD’s, a semitransparent Schottky contact can also serve as the top reflector of the resonant cavity. We present theoretical and experimental results on spectral and high-speed properties of GaAs–AlAs–InGaAs RCE Schottky PD’s designed for 900-nm wavelength

InGaAs-based high-performance p-i-n photodiodes

Cataloged from PDF version of article.In this letter, we have designed, fabricated, and characterized high-speed and high-efficiency InGaAs-based p-i-n photodetectors with a resonant cavity enhanced structure. The devices were fabricated by a microwave-compatible process. By using a postprocess recess etch, we tuned the resonance wavelength from 1605 to 1558 nm while keeping the peak efficiencies above 60%. The maximum quantum efficiency was 66% at 1572 nm which was in good agreement with our theoretical calculations. The photodiode had a linear response up to 6-mW optical power, where we obtained 5-mA photocurrent at 3-V reverse bias. The photodetector had a temporal response of 16 ps at 7-V bias. After system response deconvolution, the 3-dB bandwidth of the device was 31 GHz, which corresponds to a bandwidth-efficiency product of 20 GHz

High-speed GaAs-based resonant-cavity-enhanced 1.3 μm photodetector

Cataloged from PDF version of article.We report GaAs-based high-speed, resonant-cavity-enhanced, Schottky barrier internal photoemissionphotodiodes operating at 1.3 μm. The devices were fabricated by using a microwave-compatible fabrication process. Resonance of the cavity was tuned to 1.3 μm and a nine-fold enhancement was achieved in quantum efficiency. The photodiode had an experimental setup limited temporal response of 16 ps, corresponding to a 3 dB bandwidth of 20 GHz. © 2000 American Institute of Physic