On the Measurement of Roller Skew of Tapered Roller Bearings

Roller skew in roller bearings can cause heat generation and reduce bearing life. Therefore, design to minimise its occurrence is essential in bearing development. This study investigated the roller skew of a double row tapered roller bearing under various running conditions. A new system of measurement using two differential variable reluctance transducers (DVRT) was developed. It is evident that the roller skew of the double row tapered roller bearing can be measured. The shaft rotational speed has a significant effect on roller skew but the radial load has little effect.Peer reviewedFinal Accepted Versio

Teaching Through Screens

The COVID-19 pandemic affected educational delivery dramatically, as many classes were transferred from ground to online in just a few weeks. This research explored the impact this transfer had on teachers and students. The research focused on student motivation and productivity in the online environment, as well as teacher presence in and preparedness for the online environment. The problem statement for this research is as follows: The COVID-19 pandemic responses to education diminished teacher presence resulting in a steep decline in student motivation and productivity. In addition to an extensive literature review, three case studies to better understand what had already been successfully done at schools to encourage teacher presence online were completed through reviewing secondary sources that included journal articles. The research showed that students had a better outcome and experience in courses that included teacher- delivered e-streams and teacher-created videos. Students who were able to interact with teachers during e-streams and see their teachers during videos were more motivated and productive, as students felt a connection to the course since the teacher was actively involved. However, the research also showed that teachers needed additional training on how to create e-streams and videos. The visual solution of this research is a website that includes ideas on simple ways to use available technology to create e-streams and videos. The website provides suggestions that can be done quickly to ensure that teachers are present online and is designed for teachers that are offered no other immediate training

The structure of everyday narrative in a city market: An ethnopoetics approach

This paper considers the value of Hymesian ethnopoetics as a means of analysing everyday narrative in conditions of mobility and change. The paper offers an account of the development of ethnopoetics as a means to make visible and valorize narrative in the Native American oral tradition, and as a method of revealing culturally specific relations of form and meaning. Hymes' ethnopoetic approach viewed narrative structure as a reflection of a cultural tradition of meaning‐making. Hymes' analysis proposed that traditional narrative was a culturally shaped way of speaking, and analysis of narrative structure could reveal and recreate culture. His orientation rested on an assumption that the culture of a group was more or less stable and fixed. This paper adopts an approach to analysis based on ethnopoetics, representing everyday narrative dramatically, organized not only as lines and verses, but also as scenes and acts. Representation in scenes and acts makes visible the dynamic nature of the narrative. The paper asks whether Hymes' ground‐breaking work on ethnopoetics still has currency and purchase in 21st‐century conditions of mobility, change, and unpredictability. Analysis of everyday narrative in a city market concludes that, notwithstanding the complexity of notions of 'culture' and 'language' in such conditions, ethnopoetics can be productively applied to everyday contexts for the analysis of narrative

SP-D counteracts GM-CSF-mediated increase of granuloma formation by alveolar macrophages in lysinuric protein intolerance

<p>Abstract</p> <p>Background</p> <p>Pulmonary alveolar proteinosis (PAP) is a syndrome with multiple etiologies and is often deadly in lysinuric protein intolerance (LPI). At present, PAP is treated by whole lung lavage or with granulocyte/monocyte colony stimulating factor (GM-CSF); however, the effectiveness of GM-CSF in treating LPI associated PAP is uncertain. We hypothesized that GM-CSF and surfactant protein D (SP-D) would enhance the clearance of proteins and dying cells that are typically present in the airways of PAP lungs.</p> <p>Methods</p> <p>Cells and cell-free supernatant of therapeutic bronchoalveolar lavage fluid (BALF) of a two-year-old patient with LPI were isolated on multiple occasions. Diagnostic BALF samples from an age-matched patient with bronchitis or adult PAP patients were used as controls. SP-D and total protein content of the supernatants were determined by BCA assays and Western blots, respectively. Cholesterol content was determined by a calorimetic assay or Oil Red O staining of cytospin preparations. The cells and surfactant lipids were also analyzed by transmission electron microscopy. Uptake of Alexa-647 conjugated BSA and DiI-labelled apoptotic Jurkat T-cells by BAL cells were studied separately in the presence or absence of SP-D (1 μg/ml) and/or GM-CSF (10 ng/ml), <it>ex vivo</it>. Specimens were analyzed by light and fluorescence microscopy.</p> <p>Results</p> <p>Here we show that large amounts of cholesterol, and large numbers of cholesterol crystals, dying cells, and lipid-laden foamy alveolar macrophages were present in the airways of the LPI patient. Although SP-D is present, its bioavailability is low in the airways. SP-D was partially degraded and entrapped in the unusual surfactant lipid tubules with circular lattice, <it>in vivo</it>. We also show that supplementing SP-D and GM-CSF increases the uptake of protein and dying cells by healthy LPI alveolar macrophages, <it>ex vivo</it>. Serendipitously, we found that these cells spontaneously generated granulomas, <it>ex vivo</it>, and GM-CSF treatment drastically increased the number of granulomas whereas SP-D treatment counteracted the adverse effect of GM-CSF.</p> <p>Conclusions</p> <p>We propose that increased GM-CSF and decreased bioavailability of SP-D may promote granuloma formation in LPI, and GM-CSF may not be suitable for treating PAP in LPI. To improve the lung condition of LPI patients with PAP, it would be useful to explore alternative therapies for increasing dead cell clearance while decreasing cholesterol content in the airways.</p

Ni-MH storage test and cycle life test

Gates Aerospace Batteries is conducting two long term test programs to fully characterize the NiMH cell technology for aerospace applications. The first program analyzes the effects of long term storage upon cell performance. The second program analyzes cycle life testing and preliminary production lot testing. This paper summarizes these approaches to testing the NiMH couple and culminates with initial storage and testing recommendations. Long term storage presents challenges to deter the adverse condition of capacity fade in NiMH cells. Elevated but stabilized pressures and elevated but stabilized end-of-charge voltages also appear to be a characteristic phenomenon of long term storage modes. However, the performance degradation is dependent upon specific characteristics of the metal-hydride alloy. To date, there is no objective evidence with which to recommend the proper method for storage and handling of NiMH cells upon shipment. This is particularly critical due to limited data points that indicate open circuit storage at room temperature for 60 to 90 days will result in irrecoverable capacity loss. Accordingly a test plan was developed to determine what method of mid-term to long-term storage will prevent irrecoverable capacity loss. The explicit assumption is that trickle charging at some rate above the self-discharge rate will prevent the irreversible chemical changes to the negative electrode that result in the irrecoverable capacity loss. Another premise is that lower storage temperatures, typically 0 C for aerospace customers, will impede any negative chemical reactions. Three different trickle charge rates are expected to yield a fairly flat response with respect to recoverable capacity versus baseline cells in two different modes of open circuit. Specific attributes monitored include: end-of-charge voltage, end-of-charge pressure, mid-point discharge voltage, capacity, and end-of-discharge pressure. Cycle life testing and preliminary production lot testing continue to dominate the overall technology development effort at GAB. The cell life test program reflects continuing improvements in baseline cell designs. Performance improvements include lower and more stable charge voltages and pressures. The continuing review of production lot testing assures conformance to the design criteria and expectations. This is especially critical during this period of transferring technology from research and development status to production

A discrete slug population model determined by egg production

Slugs are significant pests in agriculture (as well as a nuisance to gardeners), and it is therefore important to understand their population dynamics for the construction of efficient and effective control measures. Differential equation models of slug populations require the inclusion of large (variable) temporal delays, and strong seasonal forcing results in a non-autonomous system. This renders such models open to only a limited amount of rigorous analysis. In this paper, we derive a novel batch model based purely upon the quantity of eggs produced at different times of the year. This model is open to considerable reduction; from the resulting two variable discrete-time system it is possible to reconstruct the dynamics of the full population across the year and give conditions for extinction or global stability and persistence. Furthermore, the steady state temporal population distribution displays qualitatively different behavior with only small changes in the survival probability of slugs. The model demonstrates how small variations in the favorability of different years may result in widely different slug population fluctuations between consecutive years, and is in good agreement with field data

Verifying a questionnaire diagnosis of asthma in children using health claims data

<p>Abstract</p> <p>Background</p> <p>Childhood asthma prevalence is widely measured by parental proxy report of physician-diagnosed asthma in questionnaires. Our objective was to validate this measure in a North American population.</p> <p>Methods</p> <p>The 2884 study participants were a subsample of 5619 school children aged 5 to 9 years from 231 schools participating in the Toronto Child Health Evaluation Questionnaire study in 2006. We compared agreement between "questionnaire diagnosis" and a previously validated "health claims data diagnosis". Sensitivity, specificity and kappa were calculated for the questionnaire diagnosis using the health claims diagnosis as the reference standard.</p> <p>Results</p> <p>Prevalence of asthma was 15.7% by questionnaire and 21.4% by health claims data. Questionnaire diagnosis was insensitive (59.0%) but specific (95.9%) for asthma. When children with asthma-related symptoms were excluded, the sensitivity increased (83.6%), and specificity remained high (93.6%).</p> <p>Conclusions</p> <p>Our results show that parental report of asthma by questionnaire has low sensitivity but high specificity as an asthma prevalence measure. In addition, children with "asthma-related symptoms" may represent a large fraction of under-diagnosed asthma and they should be excluded from the inception cohort for risk factor studies.</p

Do Questions Reflecting Indoor Air Pollutant Exposure from a Questionnaire Predict Direct Measure of Exposure in Owner-Occupied Houses?

Home characteristic questions are used in epidemiological studies and clinical settings to assess potentially harmful exposures in the home. The objective of this study was to determine whether questionnaire-reported home characteristics can predict directly measured pollutants. Sixty home inspections were conducted on a subsample of the 2006 population-based Toronto Child Health Evaluation Questionnaire. Indoor/outdoor air and settled dust samples were analyzed. Mean Fel d 1 was higher (p < 0.0001) in homes with a cat (450.58 μg/g) versus without (22.28 μg/g). Mean indoor NO2 was higher (p = 0.003) in homes with gas stoves (14.98 ppb) versus without (8.31 ppb). Self-reported musty odours predicted higher glucan levels (10554.37 μg/g versus 6308.58 μg/g, p = 0.0077). Der f 1 was predicted by the home’s age, but not by reports of carpets, and was higher in homes with mean relative humidity > 50% (61.30 μg/g, versus 6.24 μg/g, p = 0.002). Self-reported presence of a cat, a gas stove, musty odours, mice, and the home’s age and indoor relative humidity over 50% predicted measured indoor levels of cat allergens, NO2, fungal glucan, mouse allergens and dust mite allergens, respectively. These results are helpful for understanding the significance of indoor exposures ascertained by self-reporting in large epidemiological studies and also in the clinical setting

The Effects of Time Pressure on Social Cognitive Problem-Solving by Aggressive and Nonaggressive Boys

This study evaluated the effects of one potential source of arousal, namely time pressure, on the attributions made and the solutions generated in hypothetical social problem situations by aggressive and nonaggressive boys. It was predicted that time pressure would be more disruptive to the social information-processing of aggressive boys as compared to their nonaggressive peers. Thirty aggressive and 32 nonaggressive third- and fourth-grade boys were administered attribution and solution generation tasks under both untimed and time pressured conditions. Level of arousal in both conditions was assessed by experimenter observation and subject self-report. The time pressure condition re-suited in greater arousal than the untimed condition across all subjects. The predicted interaction between group and condition did not reach statistical significance; however, there was a trend suggesting that the aggressive group made more hostile attributions in the time pressured as compared to the untimed condition, whereas the nonaggressive group did not differ between the two conditions. On the solution generation measure, the time pressure condition resulted in all subjects producing a greater number of solutions overall, more types of solutions, and proportionally more aggressive solutions. Results are discussed in terms of the influence of arousal on social information-processing