Variability of structural and electronic properties of bulk and monolayer Si2Te3

Since the emergence of monolayer graphene as a promising two-dimensional material, many other monolayer and few-layer materials have been investigated extensively. An experimental study of few-layer Si2Te3 was recently reported, showing that the material has diverse properties for potential applications in Si-based devices ranging from fully integrated thermoelectrics to optoelectronics to chemical sensors. This material has a unique layered structure: it has a hexagonal closed-packed Te sublattice, with Si dimers occupying octahedral intercalation sites. Here we report a theoretical study of this material in both bulk and monolayer form, unveiling a fascinating array of diverse properties arising from reorientations of the silicon dimers between planes of Te atoms. The lattice constant varies up to 5% and the band gap varies up to 40% depending on dimer orientations. The monolayer band gap is 0.4 eV larger than the bulk-phase value for the lowest-energy configuration of Si dimers. These properties are, in principle, controllable by temperature and strain, making Si2T3 a promising candidate material for nanoscale mechanical, optical, and memristive devices.Comment: 9 pages, 4 figure

Building validation tools for knowledge-based systems

The Expert Systems Validation Associate (EVA), a validation system under development at the Lockheed Artificial Intelligence Center for more than a year, provides a wide range of validation tools to check the correctness, consistency and completeness of a knowledge-based system. A declarative meta-language (higher-order language), is used to create a generic version of EVA to validate applications written in arbitrary expert system shells. The architecture and functionality of EVA are presented. The functionality includes Structure Check, Logic Check, Extended Structure Check (using semantic information), Extended Logic Check, Semantic Check, Omission Check, Rule Refinement, Control Check, Test Case Generation, Error Localization, and Behavior Verification

Development of Naphthalene PLIF for Visualizing Ablation Products From a Space Capsule Heat Shield

The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield. To better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process would be beneficial. Here, a technique developed at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products in a hypersonic flow is applied. Although high-temperature ablation is difficult and expensive to recreate in a laboratory environment, low-temperature sublimation creates a limited physics problem that can be used to explore ablation-product transport in a hypersonic flow-field. In the current work, a subscale capsule reentry vehicle model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel. The PLIF technique provides images of the spatial distribution of sublimated naphthalene in the heat-shield boundary layer, separated shear layer, and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. PLIF images have shown high concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. It was shown that, in general, the capsule shear layer appears to be more unsteady at lower angels of attack. The PLIF images demonstrated that during a wind tunnel run, as the model heated up, the rate of naphthalene ablation increased, since the PLIF signal increased steadily over the course of a run. Additionally, the shear layer became increasingly unsteady over the course of a wind tunnel run, likely because of increased surface roughness but also possibly because of the increased blowing. Regions with a relatively low concentration of naphthalene were also identified in the capsule backshell recirculation region and are most likely the result of cross-flow-induced vortices on the capsule afterbody

MRI radiomic features are independently associated with overall survival in soft tissue sarcoma

Purpose: Soft tissue sarcomas (STS) represent a heterogeneous group of diseases, and selection of individualized treatments remains a challenge. The goal of this study was to determine whether radiomic features extracted from magnetic resonance (MR) images are independently associated with overall survival (OS) in STS. Methods and Materials: This study analyzed 2 independent cohorts of adult patients with stage II-III STS treated at center 1 (N = 165) and center 2 (N = 61). Thirty radiomic features were extracted from pretreatment T1-weighted contrast-enhanced MR images. Prognostic models for OS were derived on the center 1 cohort and validated on the center 2 cohort. Clinical-only (C), radiomics-only (R), and clinical and radiomics (C+R) penalized Cox models were constructed. Model performance was assessed using Harrell\u27s concordance index. Results: In the R model, tumor volume (hazard ratio [HR], 1.5) and 4 texture features (HR, 1.1-1.5) were selected. In the C+R model, both age (HR, 1.4) and grade (HR, 1.7) were selected along with 5 radiomic features. The adjusted c-indices of the 3 models ranged from 0.68 (C) to 0.74 (C+R) in the derivation cohort and 0.68 (R) to 0.78 (C+R) in the validation cohort. The radiomic features were independently associated with OS in the validation cohort after accounting for age and grade (HR, 2.4; Conclusions: This study found that radiomic features extracted from MR images are independently associated with OS when accounting for age and tumor grade. The overall predictive performance of 3-year OS using a model based on clinical and radiomic features was replicated in an independent cohort. Optimal models using clinical and radiomic features could improve personalized selection of therapy in patients with STS

VetCompass Australia: A National Big Data Collection System for Veterinary Science

VetCompass Australia is veterinary medical records-based research coordinated with the global VetCompass endeavor to maximize its quality and effectiveness for Australian companion animals (cats, dogs, and horses). Bringing together all seven Australian veterinary schools, it is the first nationwide surveillance system collating clinical records on companion-animal diseases and treatments. VetCompass data service collects and aggregates real-time, clinical records for researchers to interrogate, delivering sustainable and cost-effective access to data from hundreds of veterinary practitioners nationwide. Analysis of these clinical records will reveal geographical and temporal trends in the prevalence of inherited and acquired diseases, identify frequently prescribed treatments, revolutionize clinical auditing, help the veterinary profession to rank research priorities, and assure evidence-based companion-animal curricula in veterinary schools. VetCompass Australia will progress in three phases: (1) roll-out of the VetCompass platform to harvest Australian veterinary clinical record data; (2) development and enrichment of the coding (data-presentation) platform; and (3) creation of a world-first, real-time surveillance interface with natural language processing (NLP) technology. The first of these three phases is described in the current article. Advances in the collection and sharing of records from numerous practices will enable veterinary professionals to deliver a vastly improved level of care for companion animals that will improve their quality of life

Reliability and validity of the Safe Routes to school parent and student surveys

Abstract Background The purpose of this study is to assess the reliability and validity of the U.S. National Center for Safe Routes to School's in-class student travel tallies and written parent surveys. Over 65,000 tallies and 374,000 parent surveys have been completed, but no published studies have examined their measurement properties. Methods Students and parents from two Charlotte, NC (USA) elementary schools participated. Tallies were conducted on two consecutive days using a hand-raising protocol; on day two students were also asked to recall the previous days' travel. The recall from day two was compared with day one to assess 24-hour test-retest reliability. Convergent validity was assessed by comparing parent-reports of students' travel mode with student-reports of travel mode. Two-week test-retest reliability of the parent survey was assessed by comparing within-parent responses. Reliability and validity were assessed using kappa statistics. Results A total of 542 students participated in the in-class student travel tally reliability assessment and 262 parent-student dyads participated in the validity assessment. Reliability was high for travel to and from school (kappa > 0.8); convergent validity was lower but still high (kappa > 0.75). There were no differences by student grade level. Two-week test-retest reliability of the parent survey (n = 112) ranged from moderate to very high for objective questions on travel mode and travel times (kappa range: 0.62 - 0.97) but was substantially lower for subjective assessments of barriers to walking to school (kappa range: 0.31 - 0.76). Conclusions The student in-class student travel tally exhibited high reliability and validity at all elementary grades. The parent survey had high reliability on questions related to student travel mode, but lower reliability for attitudinal questions identifying barriers to walking to school. Parent survey design should be improved so that responses clearly indicate issues that influence parental decision making in regards to their children's mode of travel to school

Proposing new variables for the identification of strategic groups in franchising

The identification of strategic groups in the Spanish franchising area is the main aim of this study. The authors have added some new strategic variables (not used before) to the study and have classified franchisors between sectors and distribution strategy. The results reveal the existence of four perfectly differentiated strategic groups (types of franchisors). One of the major implications of this study is that the variables that build a strategic group vary depending on the respective sector the network operates in and its distribution strategy. This fact indicates that including sector and distribution strategy is absolutely necessary to achieve good classifications of franchisor type

Integrability of Differential-Difference Equations with Discrete Kinks

In this article we discuss a series of models introduced by Barashenkov, Oxtoby and Pelinovsky to describe some discrete approximations to the \phi^4 theory which preserve travelling kink solutions. We show, by applying the multiple scale test that they have some integrability properties as they pass the A_1 and A_2 conditions. However they are not integrable as they fail the A_3 conditions.Comment: submitted to the Proceedings of the workshop "Nonlinear Physics: Theory and Experiment.VI" in a special issue di Theoretical and Mathematical Physic

Proton and carbon ion radiotherapy for primary brain tumors delivered with active raster scanning at the Heidelberg Ion Therapy Center (HIT): early treatment results and study concepts

<p>Abstract</p> <p>Background</p> <p>Particle irradiation was established at the University of Heidelberg 2 years ago. To date, more than 400 patients have been treated including patients with primary brain tumors. In malignant glioma (WHO IV) patients, two clinical trials have been set up-one investigating the benefit of a carbon ion (18 GyE) vs. a proton boost (10 GyE) in addition to photon radiotherapy (50 Gy), the other one investigating reirradiation with escalating total dose schedules starting at 30 GyE. In atypical meningioma patients (WHO °II), a carbon ion boost of 18 GyE is applied to macroscopic tumor residues following previous photon irradiation with 50 Gy.</p> <p>This study was set up in order to investigate toxicity and response after proton and carbon ion therapy for gliomas and meningiomas.</p> <p>Methods</p> <p>33 patients with gliomas (n = 26) and meningiomas (n = 7) were treated with carbon ion (n = 26) and proton (n = 7) radiotherapy. In 22 patients, particle irradiation was combined with photon therapy. Temozolomide-based chemotherapy was combined with particle therapy in 17 patients with gliomas. Particle therapy as reirradiation was conducted in 7 patients. Target volume definition was based upon CT, MRI and PET imaging. Response was assessed by MRI examinations, and progression was diagnosed according to the Macdonald criteria. Toxicity was classified according to CTCAE v4.0.</p> <p>Results</p> <p>Treatment was completed and tolerated well in all patients. Toxicity was moderate and included fatigue (24.2%), intermittent cranial nerve symptoms (6%) and single episodes of seizures (6%). At first and second follow-up examinations, mean maximum tumor diameters had slightly decreased from 29.7 mm to 27.1 mm and 24.9 mm respectively. Nine glioma patients suffered from tumor relapse, among these 5 with infield relapses, causing death in 8 patients. There was no progression in any meningioma patient.</p> <p>Conclusions</p> <p>Particle radiotherapy is safe and feasible in patients with primary brain tumors. It is associated with little toxicity. A positive response of both gliomas and meningiomas, which is suggested in these preliminary data, must be evaluated in further clinical trials.</p