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Solitons in optical metamaterials with anti-cubic law of nonlinearity by ETEM and IGEM
摘要： This paper studies soliton perturbation in optical metamaterials, with anticubic nonlinearity. Methods: Two integration approaches, namely, the extended trial equation method (ETEM) and the improved G’/G-expansion method (IGEM) are presented. Results: Bright, dark and singular soliton solutions are retrieved. The existence criteria of these solitons in metamaterials are also demonstrated. All solutions have been verified back into its corresponding equation with the aid of maple package program. Conclusions: Finally, we believe that the executed method is robust and efficient than other methods and the obtained solutions in this paper can help us to understand the variation of solitary waves in optical metamaterials.
关键词： Solitons,Extended trial equation method,Anti-cubic nonlinearity,Improved G’/G-expansion method,Optical metamaterials
更新于2025-09-10 09:29:36
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Show me (more than) the money! Assessing the social and psychological dimensions to energy efficient lighting in Kenya
摘要： Despite economic, social and environmental benefits, the uptake of energy-saving compact fluorescent lamp light bulbs (CFLs) in Kibera, an informal settlement in Nairobi, remains low. We conducted a randomized controlled field experiment involving 651 Kibera residents assessing whether the joint impact of monetary incentives and behavioral interventions (pre-commitment and simplified information highlighting CFL benefits) could increase CFL uptake. A monetary incentive covering the incremental cost of a CFL compared to an incandescent bulb positively impacted uptake. However, adding simplified information more than tripled the impact of the monetary incentive alone, resulting in a remarkable uptake rate of about 84%. While a post endline survey conducted two years following the administration of the randomized control trial does not find lasting effects, this paper provides evidence for additional behavioral hypotheses in developing countries, also assessing the contribution of intelligence and measured discount rates to account for potential household present bias. It is to date the only intervention of its type that explores the extent to which behavioral interventions can complement monetary incentives.
关键词： Energy efficiency,Randomized controlled field trial,Behavioral intervention,Africa
更新于2025-09-10 09:29:36
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Novel Handheld Diffuse Optical Spectroscopy Probe for Breast Cancer Assessment: Clinical Study
摘要： Diffuse optical spectroscopy (DOS) and diffuse optical tomography (DOT) are non-invasive breast cancer assessment modalities which employ near-infrared (NIR) light to measure optical properties of biological tissue. These properties cannot be measured by other methods including X-ray mammography, ultrasound (US) and magnetic resonance imaging (MRI) which are main breast cancer diagnosis tools. The objective of this paper is to test and validate a recently designed and developed hand-held continuous-wave radio-frequency modulated diffuse optical spectroscopy probe in a clinical trial performed on patients who diagnosed to have breast cancer. The probe has an encapsulated light emitting diode (eLED) including four wavelengths (690 nm, 750 nm, 800 nm and 850 nm) and two photodiodes located in reflectance geometry. The direct approach method has been used to extract concentration of two main chronophers in the breast tissue including deoxy-hemoglobin (Hb) and oxy-hemoglobin (HbO2). The results of the clinical trial, which included fourteen patients, show that the RF-DOS probe can correctly classify the cancerous lesion from healthy tissue in the breast. The results prove that the absorption coefficient of the breast tumor is higher than normal tissue due to higher vascularization level in four mentioned wavelengths. Conclusively, the results show 92 percent sensitivity for the extracted absorption coefficient.
关键词： Diffuse optical spectroscopy,Optical properties of biological tissue,Breast cancer,Clinical trial
更新于2025-09-09 09:28:46
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Nematic liquid crystals of bifunctional patchy spheres
摘要： Anisotropic interactions can bring about the formation, through self-assembly, of semi-?exible chains, which in turn can give rise to nematic phases for suitable temperatures and concentrations. A minimalist model constituted of hard cylinders decorated with attractive sites has been already extensively studied numerically. Simulation data shows that a theoretical approach recently proposed is able to properly capture the physical properties of these self-assembly–driven liquid crystals. Here, we investigated a simpler model constituted of bifunctional Kern-Frenkel hard spheres which does not possess steric anisotropy but which can undergo a istropic-nematic transition as a result of their self-assembly into semi-?exible chains. For this model we compare an accurate numerical estimate of isotropic-nematic phase boundaries with theoretical predictions. The theoretical treatment, originally proposed for cylinder-like particles, has been greatly simpli?ed and its predictions are in good agreement with numerical results. Finally, we also assess a crucial, and not obvious, hypothesis used in the theory, i.e. the ability of the Onsager trial function to properly model particle orientation in the presence of aggregation, that has not been properly checked yet.
关键词： nematic phases,semi-?exible chains,Kern-Frenkel hard spheres,Anisotropic interactions,self-assembly,Onsager trial function,isotropic-nematic transition
更新于2025-09-04 15:30:14
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DukeSim: A realistic, rapid, and scanner-specific simulation framework in computed tomography
摘要： The purpose of this study was to develop a CT simulation platform that is 1) compatible with voxel-based computational phantoms, 2) capable of modeling the geometry and physics of commercial CT scanners, and 3) computationally efficient. Such a simulation platform is designed to enable the virtual evaluation and optimization of CT protocols and parameters for achieving a targeted image quality while reducing radiation dose. Given a voxelized computational phantom and a parameter file describing the desired scanner and protocol, the developed platform DukeSim calculates projection images using a combination of ray-tracing and Monte Carlo techniques. DukeSim includes detailed models for the detector quantum efficiency, quantum and electronic noise, detector crosstalk, subsampling of the detector and focal spot areas, focal spot wobbling, and the bowtie filter. DukeSim was accelerated using GPU computing. The platform was validated using physical and computational versions of a phantom (Mercury phantom). Clinical and simulated CT scans of the phantom were acquired at multiple dose levels using a commercial CT scanner (Somatom Definition Flash; Siemens Healthcare). The real and simulated images were compared in terms of image contrast, noise magnitude, noise texture, and spatial resolution. The relative error between the clinical and simulated images was less than 1.4%, 0.5%, 2.6%, and 3%, for image contrast, noise magnitude, noise texture, and spatial resolution, respectively, demonstrating the high realism of DukeSim. The runtime, dependent on the imaging task and the hardware, was approximately 2-3 minutes per rotation in our study using a computer with 4 GPUs. DukeSim, when combined with realistic human phantoms, provides the necessary toolset with which to perform large-scale and realistic virtual clinical trials in a patient and scanner-specific manner.
关键词： simulation,ray tracing,monte carlo,computational human phantoms,computed tomography,virtual clinical trial,in silico modeling,CT simulator
更新于2025-09-04 15:30:14