Prediction of the Compressive Strength and Dynamic Modulus of Fiber Reinforced Concrete by Ultrasonic Pulse Velocity Measurement at Early Ages

This research investigates the relationship between early age ultrasonic pulse velocity and the compressive strength and dynamic modulus of steel, polypropylene, nylon, and glass fiber reinforced concrete. Previous studies prove that adding fibers to concrete alters the propagation of ultrasonic pulse velocity waves. Therefore, each type of fiber-reinforced concrete will have a unique relationship between ultrasonic pulse velocity and its compressive strength and dynamic modulus depending on fiber type, fiber volume fraction, water to cement ratio, and test age. To test this hypothesis, an experimental program comprising of one hundred eighty-nine 100 mm x 200 mm fiber reinforced concrete cylinders with varying fiber types, fiber volume fractions, and water-to-cement ratios will be tested using destructive and nondestructive test methods at the ages of 1, 3, 7, and 28 days. This research develops simple mathematical equations capable of predicting the compressive strength and dynamic modulus of different types of fiber-reinforced concrete based on early age ultrasonic pulse velocity. The equations for the prediction of the early age compressive strength of FRC had a coefficient of variation ranging from 6.4% to 14.6%. The equations for the prediction of the early age dynamic modulus of FRC had a coefficient of variation ranging from 3.3% to 9.2%. These equations can predict the compressive strength and dynamic modulus of multiple types of fiber reinforced concrete due to the incorporation of different fiber properties as variables in the equations

Rhegmatogenous retinal detachment masquerading as exudative panuveitis with intense anterior chamber inflammatory reaction.

Purpose:This is a retrospective case report illustrating the diagnostic and therapeutic challenges associated with a chronic rhegmatogenous retinal detachment masquerading as a severe panuveitis with intense anterior chamber inflammation. We have included clinical features, anterior segment and fundus photography, B-scan ultrasonography, fluorescein angiography, and intraoperative findings. Observations:A 26-year-old male presented with features of unilateral panuveitis: hypotony, anterior segment inflammation (posterior synechiae and anterior chamber cell with fibrin clumping), diffuse choroidal thickening, and retinal detachment. Laboratory investigations for infectious or rheumatologic processes were negative, and empiric systemic corticosteroid therapy was unsuccessful. This prompted suspicion for an alternate primary etiology, and pars plana vitrectomy revealed small retinal breaks as the underlying cause of the retinal detachment and inflammation. Conclusions:Rhegmatogenous retinal detachments are a known cause of intraocular inflammation. Nevertheless, it remains a challenge to recognize retinal breaks in this setting, particularly with robust anterior segment inflammation and posterior findings resembling severe exudative uveitis. Being aware of this unique presentation may prevent delays in diagnosis and have important prognostic implications

Phantom Accretion by Black Holes and the Generalized Second Law of Thermodynamics

The accretion of a phantom fluid with non-zero chemical potential by black holes is discussed with basis on the Generalized Second Law of thermodynamics. For phantom fluids with positive temperature and negative chemical potential we demonstrate that the accretion process is possible, and that the condition guaranteeing the positiveness of the phantom fluid entropy coincides with the one required by Generalized Second Law. In particular, this result provides a complementary confirmation that cosmological phantom fluids do not need to have negative temperatures

Examining Portuguese High School Students’ Attitudes Toward Physical Education

Portugal ranks fourth among countries with the highest rate of overweight population, considering that 67.6% of the Portuguese population over the age of 15 is overweight or obese. To our knowledge, limited studies have investigated students' attitudes toward physical education in Portugal. Such research is necessary because it can provide valuable insights for policy and application in the curriculum development for physical education, which may eventually increase participation in physical and sports activities. This study analyzed students' attitudes toward physical education (PE) according to sociodemographic variables, including grade level, socioeconomic status, and gender, and their participation in extracurricular sports activities and respective PE grades. The sample comprised 476 high school students (from the 7th, 8th, and 9th-grade levels) from five public schools located in Portugal. The Students' Attitudes toward Physical Education Questionnaire was adapted and validated for use with Portuguese students as a two-factor model. Findings show that students generally have a moderately positive attitude toward PE. However, students' positive attitudes tend to decrease throughout high school, which is particularly significant in the 9th grade. Furthermore, students' attitudes are influenced by gender, extracurricular sports practice, and grades. These findings may help stakeholders reflect on how to frame PE in a more meaningful way to create a solid foundation for maintaining an active lifestyle throughout life. Implications for further research and practice are discussed.info:eu-repo/semantics/publishedVersio

Portuguese Students’ Perceptions About the Motivational Climate in Physical Education

info:eu-repo/semantics/acceptedVersio

Global Stability of a Premixed Reaction Zone (Time-Dependent Liñan’s Problem)

Global stability properties of a premixed, three-dimensional reaction zone are considered. In the nonadiabatic case (i.e., when there is a heat exchange between the reaction zone and the burned gases) there is a unique, spatially one-dimensional steady state that is shown to be unstable (respectively, asymptotically stable) if the reaction zone is cooled (respectively, heated) by the burned mixture. In the adiabatic case, there is a unique (up to spatial translations) steady state that is shown to be stable. In addition, the large-time asymptotic behavior of the solution is analyzed to obtain sufficient conditions on the initial data for stabilization. Previous partial numerical results on linear stability of one-dimensional reaction zones are thereby confirmed and extended

Influence of different pre-treatment methods on the immobilization of brewer’s yeast on corn cob particles

Fundação para a Ciência e Tecnologia (FCT

Autonomous golf ball picking robot design and development

The golf ball picking task is a daily that requires human intensive labor. This document presents the hardware developing process of an autonomous golf ball picking robot which aims to efficiently perform this task. It has a maintenance capacity of a 25,000 m2 practice field. Compared to a similar device in the market this robot has twice the maximum speed and three times more container capacity.QREN GOLFmINHO nº1583, FCt - Fundação Ciência e Tecnologia