Seismic Behaviour and Retrofit of Historic Masonry Minaret

U radu se razmatra dinamičko ponašanje blokovima zidanog minareta povijesne džamije u Istanbulu i metoda protupotresne sanacije. S obzirom na visoku seizmičku aktivnost regije, za određivanje bočnih pomaka i načina otkazivanja uslijed seizmičkih djelovanja odabran je prostorni model konačnih elemenata. Provedene analize pokazuju da se najveća oštećenja obično pojavljuju u podnožju i donjem dijelu minareta, te da se ojačavanjem tih dijelova trakama od polimera armiranog vlaknima (engl. FRP - Fiber Reinforced Polymer) poboljšava otpornost na bočne sile. Postignuti rezultati su u smislu seizmičke zaštite obećavajući.The dynamic behaviour of block masonry minaret of a historical mosque in Istanbul is analyzed, and a seismic retrofit method is proposed. Due to high seismicity of the region, a 3D finite element model is used to determine lateral displacements and failure modes under seismic load. The analyses show that the highest damage usually occurs at the base and the lower part of the minaret, and that lateral behaviour can be improved by strengthening these sections with fiber reinforced polymer (FRP) sheets. The results obtained are promising in terms of seismic protection

Measuring Online Student Engagement in Higher Education: Scale Development, Validation, and Psychometric Properties

Student engagement in online learning environments is of particular importance to successful learning experiences due to the unique features of online learning environments (e.g., physical distance, sense of isolation from peers and instructors). Reliable and valid assessment of student engagement is vitally important for making evidence-based decisions for online learning environments. Addressing this need and the limitations of the existing measures, this study presents a tool to assess student engagement in online learning environments, the Online Engagement in Higher Education (OEHE), which has been validated through a series of confirmatory factor analyses, as well as additional validity analyses, and internal consistency reliability analysis. Using data from 235 undergraduate and graduate students, who took at least one online course during the time of data collection in Fall 2021, a hypothesized three-factor model of online student engagement based on Fredricks et al.’s (2004) engagement framework focusing on three core dimensions of behavioral, emotional, and cognitive engagement was adequately confirmed in the context of CFA. The OEHE was also shown to have reasonable evidence of convergent validity and criterion validity, and strong evidence of discriminant validity through Pearson correlations. The OEHE subscales and the final validated instrument with 20 items also were found to have adequate or very high internal consistency reliability. Implications for the OEHE instrument development and validation and recommendations for future studies are discussed to provide insights for online engagement researchers, practitioners, and other stakeholders in online education

Seismic Response Analysis of Masonry Minaret and Possible Strengthening by Fiber Reinforced Cementitious Matrix (FRCM) Materials

This paper presents the analytical study on the dynamic response of a natural stone block masonry minaret of a historical mosque located in Istanbul, Turkey. A three-dimensional finite element model of the whole minaret, adjusted with former in situ ambient vibration test results, was used in order to get probable lateral displacements, stresses, and understanding of failure modes under seismic loading. Particularly, FEM has been used to evaluate the seismic safety of the minaret in present-day condition and after the application of a proposed strengthening method. In this method, by utilizing the fiber reinforced cementitious matrix (FRCM) material, the critical cross-sections were jacketed. The appearing damage for the bare minaret obtained from FEM analyses was located at the boot and transition part of the minaret. After FRCM material was wrapped around these critical cross-sections, the analytical results indicated that such method appears effective in terms of the seismic response. It also appears less invasive in terms of the conservation of historical heritage like minarets without causing aesthetic conflict on the existing structure when compared to other available techniques

Chemical composition of subcritical water extraction extract of Tribulus Terrestris

Subcritical water extraction of Tribulus terrestris leaves and fruits was performed at 100 ºC and 60 atm for 30 min. Chemical composition of volatile extracts was investigated.  A simple lactone compound Loliolide (23,82%) was  main components associated with 26 identified molecules which are mostly oxygenated compounds

Microelement Contents and Fatty Acid Compositions of some Isatis Species Seeds

Isatis species are important biennial, herbaceous shrubs represented by 40 taxa, of which 24 are endemic to Turkey. The chemical compounds found in leaves and roots of all Isatis species have medicinal properties and are used for treatment of a wide range of disorders. No study reports seed characteristics, microelement contents and fatty acid compositions of the seeds of any Isatis species except I. tinctoria. Therefore the study was carried out to find seed fatty oil, fatty acid compositions protein content, characteristics, and microelement contents of I. aucheri, I. cochlearis, I. constricta, I. demiriziana (endemic), I. glauca and I. lusitanica. The results showed fatty oil and protein content of these species in range of 2 to 10% and 16.07 to 25.17%, respectively. Furthermore, these seeds were rich in microelements Al, Ca, Fe, K, Mg, Na and P. Major fatty oil components of these species were determined as erucic, oleic, linoleic and linolenic acid; such that erucic acid content of these species ranged 16.94 to 30.52%

Handbook for the Post-Earthquake Safety Evaluation of Bridges and Roads

It is acknowledged that the most damaging earthquake within the state took place on September 27, 1909 near the Illinois border between Vincennes and Terre Haute. Both nonstructural and structural damage occurred to the buildings in this area, and it was felt strongly in the southwest of Indiana including Indianapolis. Unfortunately, due to the long recurrence interval of strong earthquakes in Mid-America, a large inventory of structures has accumulated without explicit consideration of seismic resistance. Highway bridges are a significant component of this inventory. The seismic vulnerability of highway bridges constructed within the state, especially in southwestern portion of Indiana, presents a problem of serious consequences. The main purpose of this handbook is to provide INDOT personnel of various backgrounds with a rapid and effective methodology for the post-earthquake safety inspection of bridges and roads in Indiana. This methodology is intended to promote and maintain the uniformity of the inspection as much as possible while assessing and rating bridge and road damage. This handbook contains the material necessary for a systematic safety evaluation of bridge structures and roads for a wide range of INDOT personnel. In the handbook, the necessary material is arranged according to two inspection levels. Level 1 inspection consists of the rapid visual evaluation of the bridges and roads in the affected area to establish obviously unsafe structures and roads. The Level 1 section of the handbook is intended for INDOT personnel with a broad range of backgrounds. Level 2 inspection consists of a more in-depth safety evaluation of bridges and roads, as well as temporary repair and long-term monitoring techniques. This segment is designed specifically for INDOT engineers. The Level 2 inspection team will be expected to make a more detailed structural and geotechnical post-earthquake condition assessment of the bridge. The organization and the management of the post-earthquake inspections are under the jurisdiction of INDOT, unless declared a State Disaster by the Governor and taken over by SEMA, and it is outside the scope of this handbook

Coronary arteriovenous fistulas in the adults: natural history and management strategies

<p>Abstract</p> <p>Objective</p> <p>To describe aspects of the natural history and pathophysiology of coronary arteriovenous fistula and to propose potential treatment strategies.</p> <p>Methods</p> <p>Eleven adult patients were treated surgically for coronary arteriovenous fistulas (8 male, 3 female) during the last three years. Mean age was 48,7 ± 9,5 years (range 32-65 years). Diagnosis was made by coronary angiography and transesophageal echocardiography</p> <p>Results</p> <p>All patients were symptomatic due to the associating cardiac disorder or fistula. Presenting symptoms were chest pain, exertional dyspnea and palpitation. All patients were diagnosed by selective angiography. Transthoracic and transoesophageal echocardiography was performed to identify the Qp/Qs ratio in one patient. One patient who had an LAD to pulmonary artery coronary arteriovenous fistula with a vascular malformation needed early reoperation due to recurrence of the fistula. Echocardiographic evaluation at the postoperative third month revealed no residual shunts in all patients.</p> <p>Conclusion</p> <p>Because of the severe complications that may develop due to coronary arteriovenous fistula, we believe that every coronary artery fistula should be treated invasively by surgery or transcatheter closure. But both treatment modalities still need to be evaluated with randomized multicenter studies for long term survival and effectiveness.</p

Teaching Presence in Online Courses: Similar Perceptions but Different Experiences from Multiple Instructor Perspectives

Online course instructors’ perceptions and perspectives regarding their teaching presence as a key presence in online learning environments significantly influence, if not determine, their online teaching practices, which in turn influence the quality of online students’ learning experiences. Although gaining deeper insights into online course instructors’ perceptions and experiences of teaching presence is quite important and valuable for online education, there is still limited qualitative inquiry into this critical presence across diverse online teaching contexts. The purpose in this qualitative, multiple case study was to explore and understand online course instructors’ perceptions and experiences regarding their own presence in their online courses. We explored the perceptions and experiences of eight course instructors teaching undergraduate and graduate-level online courses at a midwestern U.S. college. Our findings indicated that teaching presence was uniformly considered important and necessary by the instructors although their applications and priorities regarding their teaching presence varied. We discussed our themes that emerged from our interview data and offered several theoretical and practical implications regarding teaching presence in online learning environments

Comparison of Shear Bond Strengths of Ceramic Brackets Using Either Self-etching Primer or Conventional Method After Intracoronal Bleaching

Objective:To evaluate initial shear bond strengths (SBSs) of ceramic brackets using either a self-etching primer (SEP) or the conventional method (CM) after intracoronal bleaching with sodium perborate and distilled water.Materials and Method:Eighty human incisors were divided into 4 groups according to bleaching and bonding procedures: group 1, bleaching was not applied and brackets were bonded with SEP; group 2, bleaching was not applied and brackets were bonded with the CM; group 3, intracoronal bleaching with sodium perborate was applied for 3 weeks and brackets were bonded with SEP; group 4, intracoronal bleaching with sodium perborate was applied for 3 weeks and brackets were bonded with the CM. The SEP (Transbond Plus) was applied as recommended by the manufacturer. After SEP application, ceramic brackets were bonded with light cure adhesive (Transbond XT). For the CM, the teeth were etched with 37% phosphoric acid. After etching, a thin uniform coat of primer (Transbond XT Primer) was applied and ceramic brackets were bonded with light cure adhesive (Transbond XT). The SBSs were measured after water storage for 30 days, after 1000 cycles of thermocycling between 58C and 558C. Bond failure location was determined with the adhesive remnant index (ARI).Results:For the SEP method, there was no significant difference between the SBS values of the bleaching and nonbleaching groups. Furthermore, for the CM, the SBS value of the nonbleaching group was not significantly different from that of the bleaching group. The SBS values of the SEP method presented significant differences from the SBS values of the CM (p , 0.001). The SBS values of the SEP application decreased with and without bleaching. ARI scores did not show any significant difference between the groups (p = 0.174).Conclusion:Intracoronal bleaching with sodium perborate and distilled water did not affect the SBS values of ceramic brackets