Frequency-tunable metamaterials using broadside-coupled split ring resonators

We present frequency tunable metamaterial designs at terahertz (THz) frequencies using broadside-coupled split ring resonator (BC-SRR) arrays. Frequency tuning, arising from changes in near field coupling, is obtained by in-plane horizontal or vertical displacements of the two SRR layers. For electrical excitation, the resonance frequency continuously redshifts as a function of displacement. The maximum frequency shift occurs for displacement of half a unit cell, with vertical displacement resulting in a shift of 663 GHz (51% of f0) and horizontal displacement yielding a shift of 270 GHz (20% of f0). We also discuss the significant differences in tuning that arise for electrical excitation in comparison to magnetic excitation of BC-SRRs

Optically thin composite resonant absorber at the near-infrared band: a polarization independent and spectrally broadband configuration

Cataloged from PDF version of article.We designed, fabricated, and experimentally characterized thin absorbers utilizing both electrical and magnetic impedance matching at the near-infrared regime. The absorbers consist of four main layers: a metal back plate, dielectric spacer, and two artificial layers. One of the artificial layers provides electrical resonance and the other one provides magnetic resonance yielding a polarization independent broadband perfect absorption. The structure response remains similar for the wide angle of incidence due to the sub-wavelength unit cell size of the constituting artificial layers. The design is useful for applications such as thermal photovoltaics, sensors, and camouflage. (C)2011 Optical Society of Americ

PHOTOGRAMMETRIC MODEL OPTIMIZATION IN DIGITALIZATION OF ARCHITECTURAL HERITAGE: YEDIKULE FORTRESS

The idea of "digitalization of architectural heritage" has recently gained prominence to represent architectural and historical assets. With all these potentials, this study aims to create optimized models that can be used in serious gaming environments by presenting a method of photogrammetry. As a case study, Yedikule Fortress and its surroundings, which have a multi-layered structure that includes many cultural aspects such as Byzantine, Ottoman, and Republican periods in the historical process, have been studied within the scope of digitizing the architectural heritage to create an optimized model for gaming environments. The study was methodologically constructed in three phases: Photogrammetry, polygon modeling, and low poly/high poly baking process. The fortress and its surroundings are modeled using a high-detail point cloud and a high-poly mesh using aerial photogrammetry. The high-poly model was taken as a reference and transferred into a low-poly model as a mesh map, texture, and light characteristics. This allowed the high poly model to operate more efficiently and effectively in game engines. As a result, the study created a detailed and optimized model for the game engines to produce serious games specific to light and texture data, to be used on devices that support mixed reality (MR) technologies

Software defect prediction: do different classifiers find the same defects?

Open Access: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.During the last 10 years, hundreds of different defect prediction models have been published. The performance of the classifiers used in these models is reported to be similar with models rarely performing above the predictive performance ceiling of about 80% recall. We investigate the individual defects that four classifiers predict and analyse the level of prediction uncertainty produced by these classifiers. We perform a sensitivity analysis to compare the performance of Random Forest, Naïve Bayes, RPart and SVM classifiers when predicting defects in NASA, open source and commercial datasets. The defect predictions that each classifier makes is captured in a confusion matrix and the prediction uncertainty of each classifier is compared. Despite similar predictive performance values for these four classifiers, each detects different sets of defects. Some classifiers are more consistent in predicting defects than others. Our results confirm that a unique subset of defects can be detected by specific classifiers. However, while some classifiers are consistent in the predictions they make, other classifiers vary in their predictions. Given our results, we conclude that classifier ensembles with decision-making strategies not based on majority voting are likely to perform best in defect prediction.Peer reviewedFinal Published versio

Study satisfaction among university students during the COVID-19 pandemic: longitudinal development and personal-contextual predictors

The COVID-19 pandemic challenges the well-being and academic success of many students. Yet, little is known about students’ study satisfaction during the COVID-19 pandemic, a multilayered construct which accounts for students’ subjective cognitive well-being and academic success. Besides, previous studies on study satisfaction are mostly cross-sectional and hardly consider the distinct subdimensions of this construct. Therefore, our main goal in this study was to shed light on the understudied development of the subdimensions of study satisfaction (i.e., satisfaction with study content, conditions of studying, and coping with study-related stress) in two semesters amid the COVID-19 pandemic. Additionally, we examined how particular personal (i.e., gender, age, GPA, intrinsic motivation, motivational cost, and academic procrastination) and contextual (i.e., loneliness) factors are related to these subdimensions. We conducted two panel studies with convenience and purposeful samples of university students in Germany (Nstudy1 = 837; Nstudy2 = 719). Participants responded online to questions on each of the subdimensions of study satisfaction at the beginning, middle, and end of each semester but responded to measures of personal and contextual factors only at the beginning of each semester. In both studies, manifest growth curve models indicated a decrease in all subdimensions of study satisfaction as the semester progressed. Generally, gender (male) and intrinsic motivation were positive predictors but age (younger students), motivational cost, and loneliness were negative predictors of different subdimensions of study satisfaction – particularly satisfaction with study content. Overall, motivational costs and loneliness were the most consistent predictors of all subdimensions of study satisfaction across both studies. Our findings provide support for the understanding that study satisfaction could diminish in the face of challenging situations such as in this pandemic. The present study also highlights certain personal and contextual factors that relate to study satisfaction and calls for intensive research into the multidimensional construct of study satisfaction

High Molecular Weight Hyaluronan Promotes Corneal Nerve Growth in Severe Dry Eyes

The purpose of this study was to investigate the effect of high molecular weight hyaluronan (HMWHA) eye drops on subbasal corneal nerves in patients suffering from severe dry eye disease (DED) and to evaluate the damage of subbasal corneal nerves associated with severe DED. Designed as an international, multicenter study, 16 patients with symptoms of at least an Ocular Surface Disease Index (OSDI) score of 33, and corneal fluorescein staining (CFS) of at least Oxford grade 3, were included and randomized into two study arms. The control group continued to use their individual optimum artificial tears over the study period of eight weeks; in the verum group, the artificial tears were substituted by eye drops containing 0.15% HMWHA. At the baseline visit, and after eight weeks, the subbasal nerve plexus of 16 patients were assessed by confocal laser scanning microscopy (CSLM). The images were submitted to a masked reading center for evaluation. Results showed a significant increase of total nerve fiber lengths (CNFL) in the HMWHA group (p = 0.030) when compared to the control group, where the total subbasal CNFL did not significantly change from baseline to week 8. We concluded that in severe DED patients, HMWHA from topically applied eye drops could cross the epithelial barrier and reach the subbasal nerve plexus, where it exercised a trophic effect

Diaphragmatic rupture with right colon and small intestine herniation after blunt trauma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Traumatic diaphragmatic hernias are an unusual presentation of trauma, and are observed in about 10% of diaphragmatic injuries. The diagnosis is often missed because of non-specific clinical signs, and the absence of additional intra-abdominal and thoracic injuries.</p> <p>Case presentation</p> <p>We report a case of a 59-year-old Italian man hospitalized for abdominal pain and vomiting. His medical history included a blunt trauma seven years previously. A chest X-ray showed right diaphragm elevation, and computed tomography revealed that the greater omentum, a portion of the colon and the small intestine had been transposed in the hemithorax through a diaphragm rupture. The patient underwent laparotomy, at which time the colon and small intestine were reduced back into the abdomen and the diaphragm was repaired.</p> <p>Conclusions</p> <p>This was a unusual case of traumatic right-sided diaphragmatic hernia. Diaphragmatic ruptures may be revealed many years after the initial trauma. The suspicion of diaphragmatic rupture in a patient with multiple traumas contributes to early diagnosis. Surgical repair remains the only curative treatment for diaphragmatic hernias. Prosthetic patches may be a good solution when the diaphragmatic defect is severe and too large for primary closure, whereas primary repair remains the gold standard for the closure of small to moderate sized diaphragmatic defects.</p

Mean platelet volume could be a promising biomarker to monitor dietary compliance in celiac disease

Background. Celiac disease (CD) is an autoimmune disease that develops in patients with a genetic predisposition, incurring a susceptibility to gluten-containing foods such as barley, wheat, and rye. The elimination of gluten from the diet is the main therapeutic approach and usually leads to clinical and laboratory improvement. There are no ideal markers that objectively assess dietary compliance in CD patients. Materials and methods. Sixty newly diagnosed CD patients (male/female: 43/17) and 40 healthy subjects (male/female: 23/17) were enrolled in this study. The diagnosis of CD was established by both histological findings of duodenum biopsy (total villous atrophy and lymphocytic infiltration) and positive antibodies against endomysium or gliadin. Results. A significantly higher mean platelet volume (MPV) was observed in the CD group compared with healthy subjects (8.45 +/- 0.96 fL versus 7.93 +/- 0.63 fL; p = 0.004). After introduction of a gluten-free diet, the MPV of CD patients in the dietary adherent group was significantly lower than that of the non-adherent group (8.09 +/- 0.6 fL versus 8.9 +/- 1.08 fL; p = 0.001). Overall dietary adherence rate was 71.6% (43/60 CD patients). In the dietary compliant group, initiation of gluten-free diet was associated with a significant decrease in MPV from base-line values (8.56 fL versus 8.25 fL; p = 0.008). In the non-adherent group, MPV on 3-month follow-up was higher than at base-line (8.05 fL versus 8.91 fL; p = 0.001). Conclusion. MPV could be a promising and easily available biomarker for monitoring of dietary adherence in CD patients at a low cost in comparison with other modalities.WoSScopu