Classification and quantification of damage due to abrasion in various self-consolidating concrete mixtures using acoustic emission monitoring

The purpose of this thesis was to evaluate and compare the abrasion resistance of various self-consolidating concrete types by means of acoustic emission (AE) analysis. The variables adjusted throughout the study were the type of concrete (normal concrete and self-consolidating concrete), the type of supplementary cementing materials (SCM), the crumb rubber (CR) content and the inclusion of synthetic fibers (SF) of varying lengths and types (flexible and semi-rigid). The abrasion test was performed on cubic concrete specimens in accordance with the rotating-cutter method. Results from the three abrasion tests showed that metakaolin (MK) had the highest abrasion resistance among the mixtures which incorporated SCMs, CR was found to negatively affect the abrasion resistance of the tested samples and flexible SFs exhibited better abrasion resistance compared to their semi-rigid fiber counterparts. Also, the shorter fibers had more resistance capacity against abrasion than the longer fibers of the same type. The effect of changing the aforementioned variables on the abrasion behaviour was evaluated based on the abrasion data and with the assistance of AE analysis. AE signal characteristics such as amplitude, number of hits, and cumulative signal strength were gathered during the test period for each sample. Three additional parameters were determined through b-value analysis and intensity analysis which produced severity (Sr), and historic index (H (t)). The results from the entire study showed a direct correlation between the previously mentioned AE parameters and the abrasion damage in all tested mixtures. The results also allowed for damage classification charts to be developed using the AE intensity parameters [H(t) and Sr] to determine the ranges that indicate the extent of damage due to the abrasion of the tested specimens

The Ursinus Weekly, October 11, 1973

Ursinus hires seven new faculty members for term • Sororities go bananas as bids are accepted • USGA is as potent as students permit • Freshmen elect officers despite near fight over voting procedure • Lord Caradon to speak at next Ursinus forum • Editorial: President Pettit’s letter, Is it bull - - - -? • Faculty portrait: Dr. Peter Perreten • Alumni corner: Alumni leaders seek firmer ties with students • Summer school in review: Japanese-American interaction encouraged • Christian fellowship plans busy fall • Ursinus Bearettes spark southern tournament • Ursinus Booters 2-1 • Cross country eyes MAC championshiphttps://digitalcommons.ursinus.edu/weekly/1001/thumbnail.jp

Development and initial validation of a mathematics-specific spatial vocabulary scale

This study describes the development and initial validation of a mathematics-specific spatial vocabulary measure for upper elementary school students. Reviews of spatial vocabulary items, mathematics textbooks, and Mathematics Common Core State Standards identified 720 mathematical terms, 148 of which had spatial content (e.g., edge). In total, 29 of these items were appropriate for elementary students, and a pilot study (59 fourth graders) indicated that nine of them were too difficult (< 50% correct) or too easy (> 95% correct). The remaining 20 items were retained as a spatial vocabulary measure and administered to 181 (75 girls, mean age = 119.73 months, SD =4.01) fourth graders, along with measures of geometry, arithmetic, spatial abilities, verbal memory span, and mathematics attitudes and anxiety. A Rasch model indicated that all 20 items assessed an underlying spatial vocabulary latent construct. The convergent and discriminant validity of the vocabulary measure was supported by stronger correlations with theoretically related (i.e., geometry) than with more distantly related (i.e., arithmetic) mathematics content and stronger relations with spatial abilities than with verbal memory span or mathematics attitudes and anxiety. Simultaneous regression analyses and structural equation models, including all measures, confirmed this pattern, whereby spatial vocabulary was predicted by geometry knowledge and spatial abilities but not by verbal memory span, mathematics attitudes and anxiety. Thus, the measure developed in this study helps in assessing upper elementary students' mathematics-specific spatial vocabulary

A Protein-Protein Interaction Map of the Trypanosoma brucei Paraflagellar Rod

We have conducted a protein interaction study of components within a specific sub-compartment of a eukaryotic flagellum. The trypanosome flagellum contains a para-crystalline extra-axonemal structure termed the paraflagellar rod (PFR) with around forty identified components. We have used a Gateway cloning approach coupled with yeast two-hybrid, RNAi and 2D DiGE to define a protein-protein interaction network taking place in this structure. We define two clusters of interactions; the first being characterised by two proteins with a shared domain which is not sufficient for maintaining the interaction. The other cohort is populated by eight proteins, a number of which possess a PFR domain and sub-populations of this network exhibit dependency relationships. Finally, we provide clues as to the structural organisation of the PFR at the molecular level. This multi-strand approach shows that protein interactome data can be generated for insoluble protein complexes

Cooperation between Apoptotic and Viable Metacyclics Enhances the Pathogenesis of Leishmaniasis

Mimicking mammalian apoptotic cells by exposing phosphatidylserine (PS) is a strategy used by virus and parasitic protozoa to escape host protective inflammatory responses. With Leishmania amazonensis (La), apoptotic mimicry is a prerogative of the intramacrophagic amastigote form of the parasite and is modulated by the host. Now we show that differently from what happens with amastigotes, promastigotes exposing PS are non-viable, non-infective cells, undergoing apoptotic death. As part of the normal metacyclogenic process occurring in axenic cultures and in the gut of sand fly vectors, a sub-population of metacyclic promastigotes exposes PS. Apoptotic death of the purified PS-positive (PSPOS) sub-population was confirmed by TUNEL staining and DNA laddering. Transmission electron microscopy revealed morphological alterations in PSPOS metacyclics such as DNA condensation, cytoplasm degradation and mitochondrion and kinetoplast destruction, both in in vitro cultures and in sand fly guts. TUNELPOS promastigotes were detected only in the anterior midgut to foregut boundary of infected sand flies. Interestingly, caspase inhibitors modulated parasite death and PS exposure, when added to parasite cultures in a specific time window. Efficient in vitro macrophage infections and in vivo lesions only occur when PSPOS and PS-negative (PSNEG) parasites were simultaneously added to the cell culture or inoculated in the mammalian host. The viable PSNEG promastigote was the infective form, as shown by following the fate of fluorescently labeled parasites, while the PSPOS apoptotic sub-population inhibited host macrophage inflammatory response. PS exposure and macrophage inhibition by a subpopulation of promastigotes is a different mechanism than the one previously described with amastigotes, where the entire population exposes PS. Both mechanisms co-exist and play a role in the transmission and development of the disease in case of infection by La. Since both processes confer selective advantages to the infective microorganism they justify the occurrence of apoptotic features in a unicellular pathogen

Persistent ER Stress Induces the Spliced Leader RNA Silencing Pathway (SLS), Leading to Programmed Cell Death in Trypanosoma brucei

Trypanosomes are parasites that cycle between the insect host (procyclic form) and mammalian host (bloodstream form). These parasites lack conventional transcription regulation, including factors that induce the unfolded protein response (UPR). However, they possess a stress response mechanism, the spliced leader RNA silencing (SLS) pathway. SLS elicits shut-off of spliced leader RNA (SL RNA) transcription by perturbing the binding of the transcription factor tSNAP42 to its cognate promoter, thus eliminating trans-splicing of all mRNAs. Induction of endoplasmic reticulum (ER) stress in procyclic trypanosomes elicits changes in the transcriptome similar to those induced by conventional UPR found in other eukaryotes. The mechanism of up-regulation under ER stress is dependent on differential stabilization of mRNAs. The transcriptome changes are accompanied by ER dilation and elevation in the ER chaperone, BiP. Prolonged ER stress induces SLS pathway. RNAi silencing of SEC63, a factor that participates in protein translocation across the ER membrane, or SEC61, the translocation channel, also induces SLS. Silencing of these genes or prolonged ER stress led to programmed cell death (PCD), evident by exposure of phosphatidyl serine, DNA laddering, increase in reactive oxygen species (ROS) production, increase in cytoplasmic Ca2+, and decrease in mitochondrial membrane potential, as well as typical morphological changes observed by transmission electron microscopy (TEM). ER stress response is also induced in the bloodstream form and if the stress persists it leads to SLS. We propose that prolonged ER stress induces SLS, which serves as a unique death pathway, replacing the conventional caspase-mediated PCD observed in higher eukaryotes