Non-linear response to electric field in extended Hubbard models

The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various non-linear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the {\it fidelity susceptibility} of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time-scales as long as the fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating regime, dissipative regime or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular

Field effect on surface states in a doped Mott-Insulator thin film

Surface effects of a doped thin film made of a strongly correlated material are investigated both in the absence and presence of a perpendicular electric field. We use an inhomogeneous Gutzwiller approximation for a single band Hubbard model in order to describe correlation effects. For low doping, the bulk value of the quasiparticle weight is recovered exponentially deep into the slab, but with increasing doping, additional Friedel oscillations appear near the surface. We show that the inverse correlation length has a power-law dependence on the doping level. In the presence of an electrical field, considerable changes in the quasiparticle weight can be realized throughout the system. We observe a large difference (as large as five orders of magnitude) in the quasiparticle weight near the opposite sides of the slab. This effect can be significant in switching devices that use the surface states for transport

Expressing Measurement Uncertainty in OCL/UML Datatypes

Uncertainty is an inherent property of any measure or estimation performed in any physical setting, and therefore it needs to be considered when modeling systems that manage real data. Although several modeling languages permit the representation of measurement uncertainty for describing certain system attributes, these aspects are not normally incorporated into their type systems. Thus, operating with uncertain values and propagating uncertainty are normally cumbersome processes, di cult to achieve at the model level. This paper proposes an extension of OCL and UML datatypes to incorporate data uncertainty coming from physical measurements or user estimations into the models, along with the set of operations de ned for the values of these types.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Ophthalmic manifestations of congenital protein C deficiency: A case report and mini review

Background: Homozygous protein C (PC) deficiency is a potentially fatal disease with ocular blinding presentation or sequela. Case presentation: A 5 month-old boy was presented for evaluation of leukocoria. He had a history of frequent bruises and PC deficiency, treated with warfarin. His intraocular pressure was normal. In the left eye leukoma with anterior segment dysgenesis, shallow anterior chamber, and cataract were observed. Fundus was not visible. B-scan revealed a closed funnel retinal detachment. His right eye had a normal anterior segment and a thin retina with anomalous retinal vascular branching at equator and peripheral retina. A fibrovascular tuft on the optic nerve head with induced traction on superior arcade was visible. Total loss of a and b wave of both were appreciated in electroretinography (ERG). Fluorescein angiography (FA) showed very severe leakage at the junction of the vascularized and non-vascularized retina and optic nerve head. Favorable outcome was achieved with lasering of avascular retina in the right eye. Conclusion: The potential for protein C deficiency should be assessed in all infants with leukocoria, anterior segment dysgenesis, retinal detachment and retinal dysplasia. Early diagnosis could save the child's life and vision. © 2020 The Author(s)

A Novel Integration of CWPO Process with Fe3O4@C and Sonication for Oxidative Degradation of 4-Chlorophenol

This current work deals with oxidative destruction of 4-chlorophenol (4-CP) with catalytic wet peroxide oxidation (CWPO) using Fe3O4@C and sonication (US) in aqueous solution. The Fe3O4@C catalyst was synthetized and characterized with Field Emission Electron Microscopy and X-Ray Diffraction. Effect of operational variables, including initial pH, catalyst dosage, H2O2 concentration, 4-CP concentration, and sonication were investigated. A removal efficiency of 99 % was obtained by the CWPO/US-Fe3O4@C process in selected conditions including pH 5, Fe3O4@C dosage of 0.8 g L–1, H2O2 concentration of 20 mM, sonication power of 300 W, and reaction time of 60 min. Results indicated significant 4-CP removal with CWPO/US-Fe3O4@C (99 %) compared to CWPO (67 %) and US (10 %). According to the results, Fe3O4@C nanocomposite can be considered a cost-effective catalyst since it demonstrated acceptable reusability performance in degradation of 4-CP by CWPO/US-Fe3O4@C process. This work is licensed under a Creative Commons Attribution 4.0 International License

ZIF-8 Modified Polypropylene Membrane: A Biomimetic Cell Culture Platform with a View to the Improvement of Guided Bone Regeneration.

PurposeDespite the significant advances in modeling of biomechanical aspects of cell microenvironment, it remains a major challenge to precisely mimic the physiological condition of the particular cell niche. Here, the metal-organic frameworks (MOFs) have been introduced as a feasible platform for multifactorial control of cell-substrate interaction, given the wide range of physical and mechanical properties of MOF materials and their structural flexibility.ResultsIn situ crystallization of zeolitic imidazolate framework-8 (ZIF-8) on the polydopamine (PDA)-modified membrane significantly raised surface energy, wettability, roughness, and stiffness of the substrate. This modulation led to an almost twofold increment in the primary attachment of dental pulp stem cells (DPSCs) compare to conventional plastic culture dishes. The findings indicate that polypropylene (PP) membrane modified by PDA/ZIF-8 coating effectively supports the growth and proliferation of DPSCs at a substantial rate. Further analysis also displayed the exaggerated multilineage differentiation of DPSCs with amplified level of autocrine cell fate determination signals, like BSP1, BMP2, PPARG, FABP4, ACAN, and COL2A. Notably, osteogenic markers were dramatically overexpressed (more than 100-folds rather than tissue culture plate) in response to biomechanical characteristics of the ZIF-8 layer.ConclusionHence, surface modification of cell culture platforms with MOF nanostructures proposed as a powerful nanomedical approach for selectively guiding stem cells for tissue regeneration. In particular, PP/PDA/ZIF-8 membrane presented ideal characteristics for using as a barrier membrane for guided bone regeneration (GBR) in periodontal tissue engineering

Assessment of Surface Soil Moisture Using High-Resolution Multi-Spectral Imagery and Artificial Neural Networks

Many crop production management decisions can be informed using data from high-resolution aerial images that provide information about crop health as influenced by soil fertility and moisture. Surface soil moisture is a key component of soil water balance, which addresses water and energy exchanges at the surface/atmosphere interface; however, high-resolution remotely sensed data is rarely used to acquire soil moisture values. In this study, an artificial neural network (ANN) model was developed to quantify the effectiveness of using spectral images to estimate surface soil moisture. The model produces acceptable estimations of surface soil moisture (root mean square error (RMSE) = 2.0, mean absolute error (MAE) = 1.8, coefficient of correlation (r) = 0.88, coefficient of performance (e) = 0.75 and coefficient of determination (R2) = 0.77) by combining field measurements with inexpensive and readily available remotely sensed inputs. The spatial data (visual spectrum, near infrared, infrared/thermal) are produced by the AggieAir™ platform, which includes an unmanned aerial vehicle (UAV) that enables users to gather aerial imagery at a low price and high spatial and temporal resolutions. This study reports the development of an ANN model that translates AggieAir™ imagery into estimates of surface soil moisture for a large field irrigated by a center pivot sprinkler system

Spatial Scale Gap Filling Using an Unmanned Aerial System: A Statistical Downscaling Method for Applications in Precision Agriculture

Applications of satellite-borne observations in precision agriculture (PA) are often limited due to the coarse spatial resolution of satellite imagery. This paper uses high-resolution airborne observations to increase the spatial resolution of satellite data for related applications in PA. A new variational downscaling scheme is presented that uses coincident aerial imagery products from “AggieAir”, an unmanned aerial system, to increase the spatial resolution of Landsat satellite data. This approach is primarily tested for downscaling individual band Landsat images that can be used to derive normalized difference vegetation index (NDVI) and surface soil moisture (SSM). Quantitative and qualitative results demonstrate promising capabilities of the downscaling approach enabling effective increase of the spatial resolution of Landsat imageries by orders of 2 to 4. Specifically, the downscaling scheme retrieved the missing high-resolution feature of the imageries and reduced the root mean squared error by 15, 11, and 10 percent in visual, near infrared, and thermal infrared bands, respectively. This metric is reduced by 9% in the derived NDVI and remains negligibly for the soil moisture products

Development of constitutive model for precast prestressed concrete segmental columns

The interest of using precast segmental columns in construction of concrete bridges has significantly increased in recent years. One research area of concrete bridges is the application of Precast Prestressed Concrete Segmental (PPCS) Column in any structural analysis software or FE program code. Modeling a PPCS column, which consists of various materials with interaction between them, is complicated and time-consuming. This research attempts to formulate the stiffness matrix of PPCS columns in order to form the constitutive model in linear form to evaluate the response of the columns. A two-dimensional finite element model is presented in the finite element package ANSYS. Parametric studies are conducted by finite element models to verify the constitutive models for the PPCS column with a different number of concrete segments. Comparison between the constitutive model and the FE program results indicates that the constitutive model is accurate enough to predict the deformation of the PPCS columns