bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust Conservative Level Set Method for 3D Mixed-Element Meshes — Application to LES of Primary Liquid-Sheet Breakup
Authors: Pringuey Thibault , Cant R. Stewart
Published: July 2016

In this article we detail the methodology developed to construct an efficient interface description technique — the robust conservative level set (RCLS) — to simulate multiphase flows on mixed-element unstructured meshes while conserving mass to machine accuracy. The approach is tailored specifically for industry as the three-dimensional unstructured approach allows for the treatment of very complex geometries. In addition, special care has been taken to optimise the trade-off between accuracy and computational cost while maintaining the robustness of the numerical method. This was achieved by solving the transport equations for the liquid volume fraction using a WENO scheme for polyhedral meshes and by adding a flux-limiter algorithm. The performance of the resulting method has been compared against established multiphase numerical methods and its ability to capture the physics of multiphase flows is demonstrated on a range of relevant test cases. Finally, the RCLS method has been applied to the simulation of the primary breakup of a flat liquid sheet of kerosene in co-flowing high-pressure gas. This quasi-DNS/LES computation was performed at relevant aero-engine conditions on a three-dimensional mixed-element unstructured mesh. The numerical results have been validated qualitatively against theoretical predictions and experimental data. In particular, the expected breakup regime was observed in the simulation results. Finally, the computation reproduced faithfully the breakup length predicted by a correlation based on experimental data. This constitutes a first step towards a quantitative validation.
Remapping-Free Adaptive GRP Method for Multi-Fluid Flows I: One Dimensional Euler Equations
Authors: Qi Jin , Wang Yue , Li Jiequan
Published: July 2016

In this paper, a remapping-free adaptive GRP method for one dimensional (1-D) compressible flows is developed. Based on the framework of finite volume method, the 1-D Euler equations are discretized on moving volumes and the resulting numerical fluxes are computed directly by the GRP method. Thus the remapping process in the earlier adaptive GRP algorithm [17,18] is omitted. By adopting a flexible moving mesh strategy, this method could be applied for multi-fluid problems. The interface of two fluids will be kept at the node of computational grids and the GRP solver is extended at the material interfaces of multi-fluid flows accordingly. Some typical numerical tests show competitive performances of the new method, especially for contact discontinuities of one fluid cases and the material interface tracking of multi-fluid cases.
A Modified Nonlocal Continuum Electrostatic Model for Protein in Water and Its Analytical Solutions for Ionic Born Models
Authors: Xie Dexuan , Volkmer Hans W.
Published: July 2016

A nonlocal continuum electrostatic model, defined as integro-differential equations, can significantly improve the classic Poisson dielectric model, but is too costly to be applied to large protein simulations. To sharply reduce the model’s complexity, a modified nonlocal continuum electrostatic model is presented in this paper for a protein immersed in water solvent, and then transformed equivalently as a system of partial differential equations. By using this new differential equation system, analytical solutions are derived for three different nonlocal ionic Born models, where a monoatomic ion is treated as a dielectric continuum ball with point charge either in the center or uniformly distributed on the surface of the ball. These solutions are analytically verified to satisfy the original integro-differential equations, thereby, validating the new differential equation system.
Efficient Dynamic Floor Field Methods for Microscopic Pedestrian Crowd Simulations
Authors: Hartmann Dirk , Hasel Peter
Published: July 2016

Floor field methods are one of the most popular medium-scale navigation concepts in microscopic pedestrian simulators. Recently introduced dynamic floor field methods have significantly increased the realism of such simulations, i.e. agreement of spatio-temporal patterns of pedestrian densities in simulations with real world observations. These methods update floor fields continuously taking other pedestrians into account. This implies that computational times are mainly determined by the calculation of floor fields. In this work, we propose a new computational approach for the construction of dynamic floor fields. The approach is based on the one hand on adaptive grid concepts and on the other hand on a directed calculation of floor fields, i.e. the calculation is restricted to the domain of interest. Combining both techniques the computational complexity can be reduced by a factor of 10 as demonstrated by several realistic scenarios. Thus on-line simulations, a requirement of many applications, are possible for moderate realistic scenarios.
Investigations on the Droplet Impact onto a Spherical Surface with a High Density Ratio Multi-Relaxation Time Lattice-Boltzmann Model
Authors: Zhang Duo , Papadikis K. , Gu Sai
Published: July 2016

In the current study, a two-dimensional multi-relaxation time (MRT) lattice Boltzmann model which can tolerate high density ratios and low viscosity is employed to simulate the liquid droplet impact onto a curved target. The temporal variation of the film thickness at the north pole of the target surface is investigated. Three different temporal phases of the dynamics behavior, namely, the initial drop deformation phase, the inertia dominated phase and the viscosity dominated phase are reproduced and studied. The effect of the Reynolds number, Weber number and Galilei number on the film flow dynamics is investigated. In addition, the dynamic behavior of the droplet impact onto the side of the curved target is shown, and the effect of the contact angle, the Reynolds number and the Weber number are investigated.
Numerical Study of Singularity Formation in Relativistic Euler Flows
Authors: Gremaud Pierre A. , Sun Yi
Published: July 2016

The formation of singularities in relativistic flows is not well understood. Smooth solutions to the relativistic Euler equations are known to have a finite lifespan; the possible breakdown mechanisms are shock formation, violation of the subluminal conditions and mass concentration. We propose a new hybrid Glimm/central-upwind scheme for relativistic flows. The scheme is used to numerically investigate, for a family of problems, which of the above mechanisms is involved.
Super-Grid Modeling of the Elastic Wave Equation in Semi-Bounded Domains
Authors: Petersson N. Anders , Sjögreen Björn
Published: July 2016

We develop a super-grid modeling technique for solving the elastic wave equation in semi-bounded two- and three-dimensional spatial domains. In this method, waves are slowed down and dissipated in sponge layers near the far-field boundaries. Mathematically, this is equivalent to a coordinate mapping that transforms a very large physical domain to a significantly smaller computational domain, where the elastic wave equation is solved numerically on a regular grid. To damp out waves that become poorly resolved because of the coordinate mapping, a high order artificial dissipation operator is added in layers near the boundaries of the computational domain. We prove by energy estimates that the super-grid modeling leads to a stable numerical method with decreasing energy, which is valid for heterogeneous material properties and a free surface boundary condition on one side of the domain. Our spatial discretization is based on a fourth order accurate finite difference method, which satisfies the principle of summation by parts. We show that the discrete energy estimate holds also when a centered finite difference stencil is combined with homogeneous Dirichlet conditions at several ghost points outside of the far-field boundaries. Therefore, the coefficients in the finite difference stencils need only be boundary modified near the free surface. This allows for improved computational efficiency and significant simplifications of the implementation of the proposed method in multi-dimensional domains. Numerical experiments in three space dimensions show that the modeling error from truncating the domain can be made very small by choosing a sufficiently wide super-grid damping layer. The numerical accuracy is first evaluated against analytical solutions of Lamb’s problem, where fourth order accuracy is observed with a sixth order artificial dissipation. We then use successive grid refinements to study the numerical accuracy in the more complicated motion due to a point moment tensor source in a regularized layered material.
Investigation of Possible Half-Metallic Antiferromagnets on Double Perovskites A2BB′O6 (A=Ca, Sr Ba; B,B′=Transition Metal Elements)
Authors: Chen S. H. , Xiao Z. R. , Liu Y. P. , Wang Y. K.
Published: July 2016

A search was made for possible half-metallic (HM) antiferromagnet (AFM) in all the double perovskites structures of Sr2BB'O6 where BB' pairs are any combination of 3d, 4d or 5d transition elements with the exception of La. Sr can also be replaced by Ca or Ba whenever HM-AFM was found and similar calculations were then performed in order to probe further possibilities. It was found that A2MoOsO6, A2TcReO6, A2CrRuO6, where A=Ca, Sr, Ba, are all potential candidates for HM-AFM. The AFM of A2BB'O6 comes from both the superexchange mechanism and the generalized double exchange mechanism via the B(t2g)-O2pπ-B'(t2g) coupling, With the latter also being the origin of their HM. Also considered were the effects of spin-orbit coupling (SOC) and correlation (+U) by introducing +SOC and +U corrections. It is found that the SOC effect has much less influence than the correlation effect on the HM property of the compounds. For A2TcReO6 and A2CrRuO6, after +U, they become nearly Mott-Insulators. In the future, it is hoped that there will be further experimental confirmation for these possible HM-AFM candidates.
A Nominally Second-Order Cell-Centered Finite Volume Scheme for Simulating Three-Dimensional Anisotropic Diffusion Equations on Unstructured Grids
Authors: Jacq Pascal , Maire Pierre-Henri , Abgrall Rémi
Published: July 2016

We present a finite volume based cell-centered method for solving diffusion equations on three-dimensional unstructured grids with general tensor conduction. Our main motivation concerns the numerical simulation of the coupling between fluid flows and heat transfers. The corresponding numerical scheme is characterized by cell-centered unknowns and a local stencil. Namely, the scheme results in a global sparse diffusion matrix, which couples only the cell-centered unknowns. The space discretization relies on the partition of polyhedral cells into sub-cells and on the partition of cell faces into sub-faces. It is characterized by the introduction of sub-face normal fluxes and sub-face temperatures, which are auxiliary unknowns. A sub-cellbased variational formulation of the constitutive Fourier law allows to construct an explicit approximation of the sub-face normal heat fluxes in terms of the cell-centered temperature and the adjacent sub-face temperatures. The elimination of the sub-face temperatures with respect to the cell-centered temperatures is achieved locally at each node by solving a small and sparse linear system. This systemis obtained by enforcing the continuity condition of the normal heat flux across each sub-cell interface impinging at the node under consideration. The parallel implementation of the numerical algorithm and its efficiency are described and analyzed. The accuracy and the robustness of the proposed finite volumemethod are assessed bymeans of various numerical test cases.
Lack of Information Hides the Impact of Human Activities in Estuarine Fish From Southern of Brazil
Authors: Torres Michelle Cunha , Domingos Fabiola Xochilt Valdez , Rabitto Ines Silva , Randi Marco Antonio Ferreira , Ribeiro Ciro Alberto de Oliveira
Published: July 2016

Brazilian coast are sites of significant chemical discharge impacting the estuaries, natural “nursery” of aquatic organisms. In order to investigate the human impact in Lagoa dos Patos - South of Brazil - gills and liver of croakers Micropogonias furnieri were used as morphological biomarkers . Forty individuals from reference and polluted sites were caught in winter and summer of 2003. The individuals were measured, weighted and liver and gills samples were processed for light and transmission and scanning electron microscopy. Individuals from the polluted area (winter) showed strong morphological evidences of chemical exposure. The observed ultrastructure lesions and alterations confirmed the worst conditions of individuals from polluted site mainly in winter. The sediment remobilization due to rainfall may be the cause of chemical bioavailability. Further chemical studies are necessary in Lagoa dos Patos as the risk of exposure to biota and human populations was demonstrated.
Acute Toxicity of Mixture of Sugarcane Herbicides to Tilapia Fingerlings
Authors: Moura Monica A. M. , Jonsson Claudio M.
Published: July 2016

Sugarcane cultivation is the most important agricultural activity in the State of São Paulo, which is responsible for over half of Brazilian production of the crop. Eutrophication and contamination of hydric resources caused by agricultural chemicals are major problems related to this crop. In the case of herbicides used to control weeds, aquatic organisms can be exposed to more than one toxic agent, and combinations of such pollutants can have different effects on biological systems. The aim of this work was to evaluate the toxic effects of mixtures of herbicides widely used in sugarcane cultivation, namely tebuthiuron (TBUT), ametryn (AMT), and Velpar K (a commercial mixture of diuron (DIU) and hexazinone (HZN)), to tilapia (Oreochromis niloticus) fingerling. The herbicides showed low to moderate toxicity and AMT was notably more toxic then TBUT and DIU+HZN. The mixtures were found to be moderately toxic to the tilapia fingerling (LC50;96h were: TBUT+AMT: 10.76 mg L-1; (DIU+HZN)+TBUT: 43.09 mg L-1; and (DIU+HZN)+TBUT+AMT: 11.90 mg L-1), and a slight antagonism was observed between the components tested. These findings could contribute to the establishment of maximum permissible levels for the herbicides in Brazilian continental water bodies.
Effect of tropical cyclones on the stratosphere–troposphere exchange
observed using satellite observations over the north Indian Ocean
Authors: Venkat Ratnam M. , Ravindra Babu S. , Das S. S. , Basha G. , Krishnamurthy B. V. , Venkateswararao B.
Published: July 2016

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere–troposphere exchange (STE) processes in the upper troposphere and lower stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) radio occultation (RO) measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K), and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and consequentially the STE in the UTLS region.
A semi-empirical model for mesospheric and stratospheric NOy produced by energetic particle precipitation
Authors: Funke Bernd , López-Puertas Manuel , Stiller Gabriele P. , Versick Stefan , von Clarmann Thomas
Published: July 2016

Abstract. The MIPAS Fourier transform spectrometer on board Envisat has measured global distributions of the six principal reactive nitrogen (NOy) compounds (HNO3, NO2, NO, N2O5, ClONO2, and HNO4) during 2002–2012. These observations were used previously to detect regular polar winter descent of reactive nitrogen produced by energetic particle precipitation (EPP) down to the lower stratosphere, often called the EPP indirect effect. It has further been shown that the observed fraction of NOy produced by EPP (EPP-NOy) has a nearly linear relationship with the geomagnetic Ap index when taking into account the time lag introduced by transport. Here we exploit these results in a semi-empirical model for computation of EPP-modulated NOy densities and wintertime downward fluxes through stratospheric and mesospheric pressure levels. Since the Ap dependence of EPP-NOy is distorted during episodes of strong descent in Arctic winters associated with elevated stratopause events, a specific parameterization has been developed for these episodes. This model accurately reproduces the observations from MIPAS and is also consistent with estimates from other satellite instruments. Since stratospheric EPP-NOy depositions lead to changes in stratospheric ozone with possible implications for climate, the model presented here can be utilized in climate simulations without the need to incorporate many thermospheric and upper mesospheric processes. By employing historical geomagnetic indices, the model also allows for reconstruction of the EPP indirect effect since 1850. We found secular variations of solar cycle-averaged stratospheric EPP-NOy depositions on the order of 1 GM. In particular, we model a reduction of the EPP-NOy deposition rate during the last 3 decades, related to the coincident decline of geomagnetic activity that corresponds to 1.8 % of the NOy production rate by N2O oxidation. As the decline of the geomagnetic activity level is expected to continue in the coming decades, this is likely to affect the long-term NOy trend by counteracting the expected increase caused by growing N2O emissions.
Real time retrieval of volcanic cloud particles and SO2 by satellite
using an improved simplified approach
Authors: Pugnaghi Sergio , Guerrieri Lorenzo , Corradini Stefano , Merucci Luca
Published: July 2016

Abstract. Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a volcanic cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the volcanic cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the volcanic cloud. This new version takes into account the layer of atmosphere above the cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the volcanic cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajökull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajökull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajökull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.
Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra
Authors: Juszak Inge , Eugster Werner , Heijmans Monique M. P. D. , Schaepman-Strub Gabriela
Published: July 2016

Abstract. Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17 ± 0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture.
Parameter regionalization of a monthly water balance model for the
conterminous United States
Authors: Bock Andrew R. , Hay Lauren E. , McCabe Gregory J. , Markstrom Steven L. , Atkinson R. Dwight
Published: July 2016

Abstract. A parameter regionalization scheme to transfer parameter values from gaged to ungaged areas for a monthly water balance model (MWBM) was developed and tested for the conterminous United States (CONUS). The Fourier Amplitude Sensitivity Test, a global-sensitivity algorithm, was implemented on a MWBM to generate parameter sensitivities on a set of 109 951 hydrologic response units (HRUs) across the CONUS. The HRUs were grouped into 110 calibration regions based on similar parameter sensitivities. Subsequently, measured runoff from 1575 streamgages within the calibration regions were used to calibrate the MWBM parameters to produce parameter sets for each calibration region. Measured and simulated runoff at the 1575 streamgages showed good correspondence for the majority of the CONUS, with a median computed Nash–Sutcliffe efficiency coefficient of 0.76 over all streamgages. These methods maximize the use of available runoff information, resulting in a calibrated CONUS-wide application of the MWBM suitable for providing estimates of water availability at the HRU resolution for both gaged and ungaged areas of the CONUS.
Upscaling instantaneous to daily evapotranspiration using
modelled daily shortwave radiation for remote sensing applications: an Artificial Neural Network approach
Authors: Wandera Loise , Mallick Kaniska , Kiely Gerard , Roupsard Olivier , Peichl Matthias , Magliulo Vicenzo
Published: July 2016

Abstract. Upscaling instantaneous evapotranspiration retrieved at any specific time-of-daytime (ETi) to daily evapotranspiration (ETd) is a key challenge in regional scale vegetation water use mapping using polar orbiting sensors. Various studies have unanimously cited the short wave incoming radiation (RS) to be the most robust reference variable explaining the ratio between ETd and ETi on the terrestrial surfaces. This study aims to contribute in ETi upscaling for global studies using the ratio between daily and instantaneous incoming short wave radiation (RSd/RSi) as a factor for converting ETi to ETd. The approach relies on the availability of RSd measurements that in many cases is hindered if not by cost but due to the environmental conditions such as cloudiness. This paper proposes an artificial neural network (ANN) machine learning algorithm first to predict RSd from RSi followed by using the RSd/RSi ratio to convert ETi to ETd across different terrestrial ecosystem. Using RSi and RSd observations from multiple subnetworks of FLUXNET database spread across different climates and biomes (to represent inputs that would typically be obtainable from remote sensors during the overpass time) in conjunction with some astronomical variables (derived from simple mathematical computation), we developed ANN model for reproducing RSd and further used it to upscale ETi to ETd. The efficiency of the ANN is evaluated for different morning and afternoon time-of-daytime, under varying sky conditions, and also at different geographic locations. Based on the measurements from 126 sites, we found RS-based upscaled ETd to produce a significant linear relation (R2 = 0.65 to 0.69), low bias (−0.31 to −0.56 MJ m−2 d−1) (appx. 4 %), and good agreement (RMSE 1.55 to 1.86 MJ m−2 d−1) (appx. 10 %) with the observed ETd, although a systematic overestimation of ETd was also noted under persistent cloudy sky conditions. An intercomparison with existing upscaling method at daily, 8-day, monthly, and yearly temporal resolution revealed a robust performance of the ANN driven RS method and was found to produce lowest RMSE under cloudy conditions. The overall methodology appears to be promising and has substantial potential for upscaling ETi to ETd for field and regional scale evapotranspiration mapping studies using polar orbiting satellites.
Real-Time Assessment of Intraoperative Vaulting in Implantable Collamer Lens and Correlation with Postoperative Vaulting
Authors: Titiyal Jeewan S. , Kaur Manpreet , Sahu Suman , Sharma Namrata , Sinha Rajesh
Published: July 2016

Purpose

To assess the intraoperative vaulting in patients undergoing implantable collamer lens (ICL) implantation with microscope-integrated intraoperative optical coherence tomography (iOCT) and correlate it with the postoperative vaulting.

Methods

Forty eyes of 22 consecutive patients undergoing ICL implantation were prospectively evaluated. Vaulting was measured intraoperatively using microscope-integrated iOCT. The ICL-lenticular relationship was dynamically assessed throughout the surgery. Postoperative vaulting was measured using anterior segment optical coherence tomography on the first postoperative day and after 1 month and compared with the intraoperative vaulting. Uncorrected and best-corrected Snellen visual acuity, intraocular pressure (IOP), and anterior and posterior segments were assessed in all cases.

Results

The mean central vaulting noted intraoperatively was 558.4 ± 122.8 µm. Postoperative mean vaulting was 576.0 ± 131.2 µm on day 1 and 551.1 ± 122.5 µm on day 30. There was a significant correlation between the intraoperative and the postoperative day 1 vaulting (paired samples correlation: 0.969, p<0.001) and day 30 vaulting (paired samples correlation: 0.945, p<0.001). An ICL-lenticular touch was not noted at any time during the surgery. The postoperative course was uneventful and no patient developed raised IOP or lenticular changes by the last follow-up.

Conclusions

Intraoperative vaulting correlates well with postoperative vaulting and can aid in on-table detection of extremes of vaulting and decision-making. It enhances the safety of the surgical procedure by providing a real-time display of the intraoperative manipulations.
Causes of Suboptimal Corrected Visual Acuity following Phacoemulsification in a Teaching University Hospital
Authors: Fathallah Mohammed , Eltanamly Rasha M. , Saadeldin Hala , Elnahry Gehad H.
Published: July 2016

Purpose

Cataract is the leading cause of reversible blindness in developing countries, with variable visual outcome following surgery. This work aims at assessing the outcomes of cataract surgery at Kasr Al Ainy Hospital and identifying the reasons for borderline and poor outcome in the studied group.

Methods

A total of 150 eyes of patients with cataract and no other ocular pathology were included in this study. Uncorrected visual acuity (UCVA) and corrected visual acuity (CVA), complete ocular examination using slit-lamp, applanation tonometry, and ophthalmoscopy were performed for all patients. Biometry for intraocular lens power calculation and operative data were recorded. Patients were followed for 6 weeks; UCVA, CVA, and any complications were noted.

Results

Mean preoperative CVA was 0.16 ± 0.16 (SD) and mean postoperative CVA was 0.66 ± 0.33 (p<0.001). Forty-two percent of surgeries were performed by junior staff under training. Thirty-five surgeries were complicated by posterior capsular rupture. Mean CVA at 6 weeks in the uncomplicated group was 0.77 ± 0.22; in the complicated group, 0.28 ± 0.34 (p<0.001). Biometry was accurate in 51.6% of cases. Most important causes for suboptimal outcome were aphakia, astigmatism, posterior capsular opacification, and corneal edema.

Conclusions

Kasr Al Ainy Hospital achieved CVA 6/9 or more in 69.3% and CVA 6/18 or more in 81.3% of patients. The capsular complication rate was high at 23.3%. The high complication rate is attributed to the nature of the teaching hospital where most surgeons were in their learning periods.
Chorioretinal Coloboma in a Patient with Pancreas Divisum: Clinical and Imaging Features
Authors: Pierro Luisa , Corbelli Eleonora , Gagliardi Marco , Albertini Giorgia , Rabiolo Alessandro , Bandello Francesco
Published: July 2016

Purpose

To report the case of a 61-year-old woman with pancreas divisum and an asymptomatic chorioretinal coloboma in its 2 forms: complete and partial.

Methods

Case report.

Results

Dilated fundus examination and photograph revealed a complete and partial coloboma in the right eye. Swept-source optical coherence tomography and swept-source optical coherence tomography angiography (SS-OCTA) were performed. Swept-source optical coherence tomography angiography disclosed the complete coloboma as a black, round, avascular area surrounded by normal vascular tissue in every plexus (i.e., superficial, deep, and choriocapillary). Although irregular and attenuated, the vascular network of the partial coloboma was appreciable in each layer, indicating some degree of vascular preservation.

Conclusions

Chorioretinal coloboma has been linked to several ocular and systemic conditions. To our knowledge, no association between coloboma and pancreas divisum has been reported. In addition, chorioretinal coloboma has not been previously characterized by means of SS-OCTA.
La fiesta peronista: recorridos y apropiaciones entre fotografía, arquitectura efímera y poder político
Authors: Sánchez Franco Marchionni
Published: July 2016

El objetivo de este trabajo es analizar la relación entre algunos de los escenarios, fotografías y afiches utilizados como parte de las estrategias desarrolladas por el aparato de administración peronista y explicar su incidencia en la Fiesta de la Vendimia y su construcción imaginaria en torno de la “nueva Argentina” después de la Segunda Guerra Mundial. En este momento histórico particular, los registros gráficos y fotográficos considerados son una puerta de entrada para el análisis de los fenómenos efímeros que no pueden ser recuperados de otro modo. La estrategia metodológica utilizada es cualitativa y de tipo exploratorio, con un diseño de carácter flexible. Si bien estos testimonios, reflejados en las fuentes descriptas, no nos devuelven la posibilidad de estar en contacto directo con esas experiencias, sino que nos permiten acceder al conjunto de deseos, tensiones, frustraciones, expectativas, debates, los éxitos y los fracasos mediante los cuales se formularon y desarrollaron los proyectos de arquitectura escénica y propaganda política. Palabras clave: Archivos fotográficos; Arquitectura Efímera; Fiesta de la Vendimia; Relaciones de Poder; Peronismo.
Fotografias da Ditadura Civil-Militar brasileira em livros didáticos de história
Authors: Etcheverry Carolina Martins
Published: July 2016

Este artigo tem por objetivo analisar as fotografias da Ditadura presentes nos livros didáticos em circulação no Brasil no período de 1990 a 2015, a partir do ponto de vista da cultura visual. Levando-se em consideração que o livro didático de história é um produto cultural dotado de complexidade, procura-se entender o seu papel como engendrador de processos cognitivos e memoriais. Para tanto, foram pesquisados dez livros didáticos editados no período (e alguns reeditados), dos quais três são utilizados nesse artigo. Algumas mudanças na utilização e na escolha das imagens foram observadas, a exemplo da presença de retratos dos presidentes militares, muito presentes nos livros dos anos 1990, e de movimentos contrários ao regime, que passam a aparecer nas páginas dos livros dos anos 2000. O levantamento e catalogação dessas imagens poderão gerar, além de categorias de análise, novos entendimentos sobre a alteração do modo como passamos a compreender a Ditadura Militar, desde seu surgimento até o presente momento. Palavras-chave: Ensino de história; Manuais didáticos; Cultura Visual; Fotografia.
Energy gap of novel edge-defected graphene nanoribbons
Authors: Yuan Weiqing , Wen Zhongquan , Li Min , Chen Li , Chen Gang , Ruan Desheng , Gao Yang
Published: July 2016

Herein, the effects of width and boundary defects on the energy gap of graphene nanoribbons (GNRs) have been explored and theoretically investigated by means of semi-empirical atomic basis Extended Hückel method. Due to the existence of boundary defects, the energy gap of GNRs is mainly determined by the width of graphene nanoribbons for armchair graphene nanoribbons (AGNRs) or zigzag graphene nanoribbons (ZGNRs). Interestingly, the energy gap of AGNRs with a 120° V-type defect displays the monotone decreasing tendency when the width reaches to 2 nm, while the energy gap of intrinsic AGNRs is oscillatory. At the same time, the energy gap of U-type defected ZGNRs is opened, which differs from the zero energy gap characteristics of the intrinsic zigzag graphene. Furthermore, the size of energy gap of the defected AGNRs and ZGNRs with the same width is proved to be very close. Calculation results demonstrate that the energy gap of GNRs is just inversely proportional to the width and has little to do with the crystallographic direction. All the findings above provide a basis for energy gap engineering with different edge defects in GNRs and signify promising prospects in graphene-based semiconductor electronic devices.
On Teaching the History of California Spanish to HLL using Siri: Methodology and Procedures
Authors: Lamar Prieto Covadonga
Published: July 2016

This article reports results from a study in which two groups of college level students were exposed to interactions with Apple’s Siri in order to foster dialogue about their dialectal features. In this paper, the methodology and procedural challenges behind one of the activities that the participants completed are studied. These activities had been designed to present to them the historical dimensions of the Historical California Spanish dialect, or Californio Spanish, and pursue two different outcomes for the participants: 1) to foster the interest in discovering a dialectal past, and 2) to increase linguistic self-esteem, as a result of an external validation provided by technology.
Epicardial Adipose Tissue Is Increased in Patients With Inflammatory Bowel Disease
Authors: Uysal Fatma , Akbal Erdem , Akbal Ayla , Cevizci Sibel , Arık Kasım , Gazi Emine
Published: July 2016

Objectives

Patients with inflammatory bowel disease (IBD) have high cardiovascular morbidity, and, in general, epicardial adipose tissue thickness is related to atherosclerotic vascular disease. This study aimed to investigate the association between epicardial adipose tissue thickness and carotid intima‐media thickness as markers of early atherosclerosis in patients with IBD.

Methods

The study comprised 47 patients with IBD (25 with Crohn disease and 22 with ulcerative colitis) and 35 control participants. In all individuals, epicardial adipose tissue and carotid intima‐media thickness values were measured by sonography.

Results

The mean age ± SD of the 47 patients with IBD was 42.3 ± 11.2 years, versus 41.4 ± 10.1 years for the control group. The epicardial adipose tissue thickness was higher in both the Crohn disease and ulcerative colitis groups compared to the control group (P < .001), but not the carotid intima‐media thickness (P = .695 and .917, respectively). There was a strong positive correlation between the carotid intima‐media and epicardial adipose tissue thickness values in the Crohn disease and ulcerative colitis groups (r = 0.757; 95% confidence interval, 0.711–0.901; r = 0.786; 95% confidence interval, 0.364–0.615; both P < .001). However, there was no significant difference between the patients who were in the active and inactive disease periods in both groups in terms of carotid intima‐media and epicardial adipose tissue thickness values.

Conclusions

Our findings suggest that epicardial adipose tissue thickness might be a marker for detection of early atherosclerosis in patients with IBD. There was a strong positive correlation between carotid intima‐media thickness and epicardial adipose tissue thickness values in the patients with IBD. However, there was no correlation between IBD activity and carotid intima‐media or epicardial adipose tissue thickness.
Quantitative Ultrasound Assessment of Duchenne Muscular Dystrophy Using Edge Detection Analysis
Authors: Koppaka Sisir , Shklyar Irina , Rutkove Seward B. , Darras Basil T. , Anthony Brian W. , Zaidman Craig M. , Wu Jim S.
Published: July 2016

Objectives

The purpose of this study was to investigate the ability of quantitative ultrasound (US) using edge detection analysis to assess patients with Duchenne muscular dystrophy (DMD).

Methods

After Institutional Review Board approval, US examinations with fixed technical parameters were performed unilaterally in 6 muscles (biceps, deltoid, wrist flexors, quadriceps, medial gastrocnemius, and tibialis anterior) in 19 boys with DMD and 21 age‐matched control participants. The muscles of interest were outlined by a tracing tool, and the upper third of the muscle was used for analysis. Edge detection values for each muscle were quantified by the Canny edge detection algorithm and then normalized to the number of edge pixels in the muscle region. The edge detection values were extracted at multiple sensitivity thresholds (0.01–0.99) to determine the optimal threshold for distinguishing DMD from normal. Area under the receiver operating curve values were generated for each muscle and averaged across the 6 muscles.

Results

The average age in the DMD group was 8.8 years (range, 3.0–14.3 years), and the average age in the control group was 8.7 years (range, 3.4–13.5 years). For edge detection, a Canny threshold of 0.05 provided the best discrimination between DMD and normal (area under the curve, 0.96; 95% confidence interval, 0.84–1.00). According to a Mann‐Whitney test, edge detection values were significantly different between DMD and controls (P < .0001).

Conclusions

Quantitative US imaging using edge detection can distinguish patients with DMD from healthy controls at low Canny thresholds, at which discrimination of small structures is best. Edge detection by itself or in combination with other tests can potentially serve as a useful biomarker of disease progression and effectiveness of therapy in muscle disorders.
Sonographic Visualization of the Rotator Cable in Patients With Symptomatic Full‐Thickness Rotator Cuff Tears
Authors: Bureau Nathalie J. , Blain-Paré Etienne , Tétreault Patrice , Rouleau Dominique M. , Hagemeister Nicola
Published: July 2016

Objectives

To assess the prevalence of sonographic visualization of the rotator cable in patients with symptomatic full‐thickness rotator cuff tears and asymptomatic controls and to correlate rotator cable visualization with tear size, muscular fatty infiltration and atrophy, and the functional outcome in the patients with rotator cuff tears.

Methods

Fifty‐seven patients with rotator cuff tears and 30 asymptomatic volunteers underwent shoulder sonography for prospective assessment of the rotator cable and rotator cuff tear and responded to 2 functional outcome questionnaires (shortened Disabilities of the Arm, Shoulder, and Hand [QuickDASH] and Constant). In the patients with rotator cuff tears, appropriate tests were used to correlate rotator cable visualization with the tear size, functional outcome, muscular fatty infiltration, and atrophy.

Results

The patients with rotator cuff tears included 25 women and 32 men (mean age,57 years; range, 39–67 years), and the volunteers included 13 women and 17 men (mean age, 56 years; range, 35–64 years). The rotator cable was identified in 77% (23 of 30) of controls and 23% (13 of 57) of patients with rotator cuff tears. In the patients, nonvisualization of the rotator cable correlated with larger tears (P < 0.001) and higher grades of supraspinatus atrophy (P = .049) and fatty infiltration (P = .022). There was no significant correlation with functional outcome scores (QuickDASH, P = .989; Constant, P = .073) or infraspinatus fatty infiltration (P = .065).

Conclusions

Nonvisualization of the rotator cable was more prevalent in patients with symptomatic rotator cuff tears than asymptomatic controls and was associated with a larger tear size and greater supraspinatus fatty infiltration and atrophy. Diligent assessment of the supraspinatus muscle should be done in patients with rotator cuff tears without a visible rotator cable, as the integrity of these anatomic structures may be interdependent.
Cerebral Hemodynamics in the Elderly
Authors: Yang Dixon , Cabral Digna , Gaspard Emmanuel N. , Lipton Richard B. , Rundek Tatjana , Derby Carol A.
Published: July 2016

Objectives

We sought to describe the relationship between age, sex, and race/ethnicity with transcranial Doppler hemodynamic characteristics from major intracerebral arterial segments in a large elderly population with varying demographics.

Methods

We analyzed 369 stroke‐free participants aged 70 years and older from the Einstein Aging Study. Single‐gate, nonimaging transcranial Doppler sonography, a noninvasive sonographic technique that assesses real‐time cerebrovascular hemodynamics, was used to interrogate 9 cerebral arterial segments. Individual Doppler spectra and cerebral blood flow velocities were acquired, and the pulsatility index and resistive index were calculated by the device's automated waveform‐tracking function. Multiple linear regression models were used to examine the independent associations of age, sex, and race/ethnicity with transcranial Doppler measures, adjusting for hypertension, history of myocardial infarction or revascularization, and history of diabetes.

Results

Among enrolled participants, 303 individuals had at least 1 vessel insonated (mean age [SD], 80 [6] years; 63% women; 58% white; and 32% black). With age, transcranial Doppler measures of mean blood flow velocity were significantly decreased in the basilar artery (P = .001) and posterior cerebral artery (right, P = .003; left, P = .02). Pulsatility indices increased in the left middle cerebral artery (P = .01) and left anterior cerebral artery (P = .03), and the resistive index was increased in the left middle cerebral artery (P = .007) with age. Women had higher pulsatility and resistive indices compared to men in several vessels.

Conclusions

We report a decreased mean blood flow velocity and weakly increased arterial pulsatility and resistance with aging in a large elderly stroke‐free population. These referential trends in cerebrovascular hemodynamics may carry important implications in vascular diseases associated with advanced age, increased risk of cerebrovascular disease, cognitive decline, and dementia.
Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films
Authors: Maćkowski Sebastian , Czechowski Nikodem , Ashraf Khuram U. , Szalkowski Marcin , Lokstein Heiko , Cogdell Richard J. , Kowalska Dorota
Published: July 2016

We focus on the spectral dependence of plasmon‐induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60‐fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna–Matthews–Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems.
Soy‐ghretropin, a novel ghrelin‐releasing peptide derived from soy protein
Authors: Nakato Junya , Aoki Hayato , Iwakura Hiroshi , Suzuki Hideyuki , Kanamoto Ryuhei , Ohinata Kousaku
Published: July 2016

We investigated exogenous secretagogues of ghrelin, which is an orexigenic hormone isolated from the stomach. We found that the tryptic digest of soy β‐conglycinin stimulated ghrelin secretion by the ghrelin‐producing cell line, MGN3‐1. We then identified a 22‐amino acid peptide corresponding to the β‐conglycinin α‐subunit(192–213) [βCGα(192–213)] from an active fraction separated by HPLC. The N‐terminal undecapeptide of βCGα(192–213), NKNPFLFGSNR, exhibited ghrelin‐releasing activity at a lower dose than that of βCGα(192–213). We named NKNPFLFGSNR ‘soy‐ghretropin’, which corresponds to βCGα(192–202). Neither [des‐N1K2]‐soy‐ghretropin nor [des‐R11]‐soy‐ghretropin stimulated ghrelin secretion; hence, both the N‐ and C‐terminal structures of soy‐ghretropin were indispensable. Orally administered soy‐ghretropin increased plasma ghrelin levels and food intake in vivo. Soy‐ghretropin is the first exogenous ghrelin‐releasing peptide derived from food protein.