A Study of Correlations between Rock Bolt Pull-Out Tests and Rock Mass Rating Scores in Underground Mining

Rock bolt pullout testing is a common method of testing the strength of ground support in underground mining over time. Bolts that fail the pullout test fail either due to shear failure at the head of the bolt or by slipping in one piece out of structurally incompetent rock. There are many methods for quantifying rock mass strength; in this study, Bieniawski's Rock Mass Rating (RMR) system is used. This study focuses on the correlation between slipped rock bolt pullout tests with low RMR scores in underground mines. Underground mine sites participating in this study are located in Eastern Nevada, which is infamous for its low rock strength. Bolts used in this study are inflatable friction bolts, primarily Swellex bolts by Atlas Copco but with a few other manufacturers of inflatable friction bolts as well. When data was controlled for corrosive weakening of the bolt and normalized for bolt length, correlations between slipped pull-tests and low RMR scores were generally strong, positive, and statistically significant

Upper Bound on the Dark Matter Total Annihilation Cross Section

We consider dark matter annihilation into Standard Model particles and show that the least detectable final states, namely neutrinos, define an upper bound on the total cross section. Calculating the cosmic diffuse neutrino signal, and comparing it to the measured terrestrial atmospheric neutrino background, we derive a strong and general bound. This can be evaded if the annihilation products are dominantly new and truly invisible particles. Our bound is much stronger than the unitarity bound at the most interesting masses, shows that dark matter halos cannot be significantly modified by annihilations, and can be improved by a factor of 10--100 with existing neutrino experiments.Comment: 4 pages, 3 figures; version accepted for publication in PR

Molecular principles underlying dual RNA specificity in the Drosophila SNF protein

The first RNA recognition motif of the Drosophila SNF protein is an example of an RNA binding protein with multi-specificity. It binds different RNA hairpin loops in spliceosomal U1 or U2 small nuclear RNAs, and only in the latter case requires the auxiliary U2A′ protein. Here we investigate its functions by crystal structures of SNF alone and bound to U1 stem-loop II, U2A′ or U2 stem-loop IV and U2A′, SNF dynamics from NMR spectroscopy, and structure-guided mutagenesis in binding studies. We find that different loop-closing base pairs and a nucleotide exchange at the tips of the loops contribute to differential SNF affinity for the RNAs. U2A′ immobilizes SNF and RNA residues to restore U2 stem-loop IV binding affinity, while U1 stem-loop II binding does not require such adjustments. Our findings show how U2A′ can modulate RNA specificity of SNF without changing SNF conformation or relying on direct RNA contacts

Serotype k Streptococcus mutans Binding to Collagen and Fibrinogen in Nicotine

poster abstractBackground: Streptococcus mutans is a gram-positive coccus-shaped, facultatively anaerobic bacterium that is commonly found in the human oral cavity and is a major contributor to tooth decay. The bacterium has the potential to make its way into the blood stream and adhere to endothelial cell proteins such as collagen and fibrinogen in the arteries through specific receptors potentially leading to atherosclerosis. Endothelial cells secrete cell-associated and cell-free collagen and fibrinogen. Specifically, serotype k S. mutans have been associated with atherosclerosis and nicotine has been shown to increase the biofilm formation of S. mutans (serotype k). The focus of this research was to measure S. mutans ability to bind to collagen type I and fibrinogen when the cells were grown in the presence of nicotine. Methods: S. mutans serotype k strains 51, 52, and 89 were cultured in 0–2 mg/mL nicotine. Formaldehyde was added to kill the cells followed by labeling the cells with biotin. Collagen type I and fibrinogen were coated (1 μg/mL) onto 96-well microtiter plates. The plates were washed and 1% BSA was added to block the wells. Then the biotinylated nicotine-treated S. mutans were added, incubated to allow binding to the endothelial cell proteins, and washed. Finally, ExtrAvidin HRP and OPD were added to the plate and the optical density was measured at an absorbance of 490 nm. Results: The optical density was directly related to the relative number of cells bound to collagen type I and fibrinogen. Conclusion: The results demonstrated a significant increase in all three strains of S. mutans binding to the proteins when cultured in 1 and 2 mg/mL concentrations of nicotine compared to the 0 nicotine control. The increased numbers of nicotine-treated S. mutans binding to the endothelial cell proteins may have the ability to contribute to atherosclerosis

Mesenteric Vascular Dysregulation and Intestinal Inflammation Accompanies Experimental Spinal Cord Injury

Cervical and high thoracic spinal cord injury (SCI) drastically impairs autonomic nervous system function. Individuals with SCI at thoracic spinal-level 5 (T5) or higher often present cardiovascular disorders that include resting systemic arterial hypotension. Gastrointestinal (GI) tissues are critically dependent upon adequate blood flow and even brief periods of visceral hypoxia triggers GI dysmotility. The aim of this study was to test the hypothesis that T3-SCI induces visceral hypoperfusion, diminished postprandial vascular reflexes and concomitant visceral inflammation. We measured in vivo systemic arterial blood pressure and superior mesenteric artery (SMA) and duodenal blood flow in anesthetized T3-SCI rats at 3 days and 3 weeks post-injury either fasted or following enteral feeding of a liquid mixed-nutrient meal (Ensure™). In separate cohorts of fasted T3-SCI rats, markers of intestinal inflammation were assayed by qRT-PCR. Our results show that T3-SCI rats displayed significantly reduced SMA blood flow under all experimental conditions (p\u3c0.05). Specifically, the anticipated elevation of SMA blood flow in response to duodenal nutrient infusion (postprandial hyperemia) was either delayed or absent after T3-SCI. The dysregulated SMA blood flow in acutely-injured T3-SCI rats coincides with abnormal intestinal morphology and elevation of inflammatory markers, all of which resolve after 3 weeks. Specifically, Icam1, Ccl2 (MCP-1) and Ccl3 (MIP-1α) were acutely elevated following T3-SCI. Our data suggest that arterial hypotension diminishes mesenteric blood flow necessary to meet mucosal demands at rest and during digestion. The resulting GI ischemia and low-grade inflammation may be an underlying pathology leading to GI dysfunction seen following acute T3-SCI

Last Province Aboard: New Brunswick and National Medicare

Introduced as a federal-provincial cost-sharing program in the 1960s, medicare aligned ideologically with Premier Louis J. Robichaud’s Equal Opportunity program. New Brunswick was one of the first Canadian provinces to support the adoption of universal healthcare, but it was the last province to implement medicare. This article examines the federal-provincial negotiations surrounding medicare in order to shed light on the scope of Robichaud’s program of Equal Opportunity, to re-evaluate the last years of the Robichaud administration, and to explore why the Progressive Conservative government of Richard Hatfield was responsible for the implementation of medicare in New Brunswick.Le régime d’assurance-maladie, introduit dans les années 1960 comme un programme fédéral-provincial à coûts partagés, était conforme à l’idéologie du programme « Chances égales pour tous » du premier ministre Louis J. Robichaud. Le Nouveau-Brunswick fut l’une des premières provinces canadiennes à appuyer l’adoption de l’assurance-maladie universelle, mais il fut la dernière province à la mettre en œuvre. Cet article examine les négociations fédérales-provinciales entourant le programme d’assurance-maladie en vue de jeter un nouvel éclairage sur la portée du programme « Chances égales » de Robichaud, de réévaluer les dernières années de l’administration Robichaud et d’explorer pourquoi c’est le gouvernement progressiste-conservateur de Richard Hatfield qui fut responsable de la mise en œuvre de l’assurance-maladie au Nouveau-Brunswick

Effects of Nicotine on Aerobic and Anaerobic Serotype K Streptococcus mutans Biofilm Formation

poster abstractAtherosclerosis is a specific form of arteriosclerosis where the walls of arteries began to thicken as a result of bacterial invasion and accumulation of inflammatory white blood cells. There could be a direct correlation of atherosclerosis and the intake of nicotine. Nicotine has been reported to increase the amount of the cariogenic oral bacteria known as Streptococcus mutans; thus possibly leading to an increase of dental caries. Serotype K S. mutans has been associated strongly with atherosclerosis. Objective: This study focused on the biofilm formation of S. mutans serotype K when incubated in various dilutions of nicotine. Methods: S. mutans UA159 (stereotype C), and stereotype K strains 89, 52, and 51 were cultured in tryptic soy broth (TSB) overnight and then added to dilutions of TSB with 1% sucrose (TSBS) containing concentrations of nicotine between 0 and 32 mg/ml. Each dilution was added to 96-well microtiter plates, inoculated with bacteria and incubated for 24 hours aerobically at 37oC in 5% CO2 and anaerobically. The plates were treated with formaldehyde, crystal violet, and isopropanol and biofilm formation was measured at an absorbance of 490 nm. Results: Strains UA159, 89, 52, and 51 all demonstrated significantly higher biofilm formation (p<0.05) at a nicotine dilution of 8 mg/ml. When comparing the anaerobic results to the aerobic results, anaerobic incubation increased the overall biofilm formation across the majority of nicotine dilutions. Conclusion: It was established that when S. mutans strains UA159, 89, 52, and 51 were incubated anaerobically and aerobically biofilm formation was enhanced. Smoking can lead to a higher population of S. mutans in the oral cavity that potentially has traits of significantly enhanced biofilm formation when presented with moderately high levels of nicotine which may lead to increased binding to endothelial cells contributing to atherosclerosis

Does tailoring instructional style to a medical student\u27s self-perceived learning style improve performance when teaching intravenous catheter placement? A randomized controlled study.

BACKGROUND: Students may have different learning styles. It is unclear, however, whether tailoring instructional methods for a student\u27s preferred learning style improves educational outcomes when teaching procedures. The authors sought to examine whether teaching to a student\u27s self-perceived learning style improved the acquisition of intravenous (IV) catheter placement skills. The authors hypothesized that matching a medical student\u27s preferred learning style with the instructor\u27s teaching style would increase the success of placing an IV catheter. METHODS: Using the VARK model (i.e., visual [V], auditory [A], read/write [R] and kinesthetic [K]), third-year medical students reported their self-perceived learning style and were subsequently randomized to instructors who were trained to teach according to a specific learning format (i.e., visual, auditory). Success was gauged by: 1) the placement of an IV on the first attempt and 2) the number of attempts made until an IV line was successfully placed. RESULTS: The average number of attempts in the matched learning style group was 1.53, compared to 1.64 in the unmatched learning style group; however, results were not statistically significant. Both matched and unmatched groups achieved a similar success rate (57 and 58 %, respectively). Additionally, a comparison of success between the unmatched and matched students within each learning style modality yielded no statistical significance. CONCLUSIONS: Results suggest that providing procedural instruction that is congruent with a student\u27s self-perceived learning style does not appear to improve outcomes when instructing students on IV catheter placement