Design of a compliant wheel for a miniature rover to be used on Mars

The Jet Propulsion Laboratory has identified the need for a compliant wheel for a miniature martian rover vehicle. This wheel must meet requirements of minimum mass, linear radial deflection, and reliability in cryogenic conditions over a five year lifespan. Additionally, axial and tangential deflections must be no more than 10 percent of the radial value. The team designed a wheel by use of finite element and dimensionless parameter analysis. Due to the complex geometry of the wheel, a finite element model describing its behavior was constructed to investigate different wheel configurations. Axial and tangential deflections were greatly reduced but did not meet design criteria. A composite material was selected for its high strength, toughness, fatigue resistance, and damping characteristics. The team chose a Kevlar fiber filled thermoplastic composite. This report is divided into four primary sections. First, the introduction section gives background information, defines the task, and discusses the scope and limitations of the project. Second, the alternative designs section introduces alternative design solutions, addresses advantages and disadvantages of each, and identifies the parameters used to determine the best design. Third, the design solution section introduces the methods used to evaluate the alternates, and gives a description of the design process used. Finally, the conclusion and recommendations section evaluates the wheel design, and offers recommendations pertaining to improvement of the design solution

MacEwan University Wi-Fi Analysis

MacEwan Unversity has recently upgraded its wireless infrastructure on campus. The goal was to determine whether or not wireless bandwidth speeds were consistent across an area of the school, and if they were not, which areas had the strongest and weakest connections. The results could be taken as a reflection of the new system’s effectiveness and coverage. To assess wireless bandwidth speeds, both the upload and download speeds were measured across regions of the campus library using the mobile app Speedtest.net by Ookla which downloads chunks of data to a mobile device to measure connection speed. To ensure that the samples were representative, speeds were measured through various times of the day and different days of the week. These temporal dimensions were used as blocks in the experimental design. Preliminary data collection also indicated a significant difference in mobile device used, and so the use of either Apple’s iPhone 6 or Samsung’s Galaxy S3 was also selected as a block in order to prevent the age of the device becoming a nuisance factor in the experiment. In the end, the results indicated that wireless speeds were inconsistent across the library. The results provided a heat map which showed that some areas had a significantly higher bandwidth speed than other areas. The results of this study could be used to plan future changes to wireless router layout and influence new infrastructure decisions. In addition, the research methodology could be further developed and extended to any Wi-Fi or cellular service. *Indicates faculty mento

Porting or Not Porting? Availability of Exclusive Games in the Mobile App Market

Mobile games dominate the mobile app markets and contribute over half of the mobile app revenues. In order to attract more users and generate higher revenues, the platforms such as Apple iOS and Google Android, would like to partner with the game developers and have the developers exclusively stay at their own platforms to entice more consumer demands. For example, the game developer “Electronic Arts” agrees to offer Apple iOS a two-month exclusive window for the well-known mobile game “Plants vs. Zombies 2”. The benefits of the exclusivity to the platforms and app developers are unclear and not studies in the literature. This study aims (1) to provide managerial insights for the platforms and app developers, and (2) to analyze the pros and cons of the partnership strategy, e.g. when offering an exclusive deal, how do the platforms and developers maximize the corresponding profits by the exclusive deal, and what is the optimal exclusive duration

Thermal Dissipation and Variability in Electrical Breakdown of Carbon Nanotube Devices

We study high-field electrical breakdown and heat dissipation from carbon nanotube (CNT) devices on SiO2 substrates. The thermal "footprint" of a CNT caused by van der Waals interactions with the substrate is revealed through molecular dynamics (MD) simulations. Experiments and modeling find the CNT-substrate thermal coupling scales proportionally to CNT diameter and inversely with SiO2 surface roughness (~d/{\Delta}). Comparison of diffuse mismatch modeling (DMM) and data reveals the upper limit of thermal coupling ~0.4 W/K/m per unit length at room temperature, and ~0.7 W/K/m at 600 C for the largest diameter (3-4 nm) CNTs. We also find semiconducting CNTs can break down prematurely, and display more breakdown variability due to dynamic shifts in threshold voltage, which metallic CNTs are immune to; this poses a fundamental challenge for selective electrical breakdowns in CNT electronics

Quantitative Determination of Spatial Protein-protein Proximity in Fluorescence Confocal Microscopy

To quantify spatial protein-protein proximity (colocalization) in fluorescence microscopic images, cross-correlation and autocorrelation functions were decomposed into fast and slowly decaying components. The fast component results from clusters of proteins specifically labeled and the slow one from background/image heterogeneity. We show that the calculation of the protein-protein proximity index and the correlation coefficient are more reliably determined by extracting the fast-decaying component.Comment: 19 pages, 5 figure

Comparisons of the GlideScope and Macintosh Laryngoscope in Tracheal Intubation by Medical Students on Fresh Human Cadavers

AbstractObjectiveThe GlideScope Video Laryngoscope (GS) is an intubating device that provides equal or better glottic views than conventional laryngoscopes, but correct tube placement is more time-consuming, even when performed by experienced operators. The aim of this study was to investigate the use of the GS compared with the more conventional Macintosh laryngoscope in easy and difficult tracheal intubation when performed by inexperienced medical students on fresh human cadaversPatients and MethodsForty-one medical students were assigned to perform tracheal intubation using the direct Macintosh laryngoscope (DL) and the GS. Each student was given four attempts, with a maximum of 180 seconds for each attempt, to successfully intubate the trachea with a 6.5-mm tracheal tube in each of two scenarios, one with an easy airway and the other with a difficult airway cadaver.ResultsThe total time of intubation for the easy airway cadaver was significantly longer in the GS group (61.4 ± 4.8 seconds vs. 40.6 ± 5.3 seconds; p < 0.001) despite the modified Cormack-Lehane scores showing no difference between the two groups. In the difficult airway cadaver, total time of intubation was significant shorter in the GS group (64.3 ± 6.5 seconds vs. 98.7 ± 10.2 seconds; p < 0.001)ConclusionMost inexperienced operators found the GS to be more time-consuming for tracheal intubation than DL in the easy airway cadaver. However, an obvious advantage was demonstrated when the GS was used for the difficult airway

Bone morphogenetic protein 7 sensitizes O6-methylguanine methyltransferase expressing-glioblastoma stem cells to clinically relevant dose of temozolomide.

BackgroundTemozolomide (TMZ) is an oral DNA-alkylating agent used for treating patients with glioblastoma. However, therapeutic benefits of TMZ can be compromised by the expression of O6-methylguanine methyltransferase (MGMT) in tumor tissue. Here we used MGMT-expressing glioblastoma stem cells (GSC) lines as a model for investigating the molecular mechanism underlying TMZ resistance, while aiming to explore a new treatment strategy designed to possibly overcome resistance to the clinically relevant dose of TMZ (35&nbsp;μM).MethodsMGMT-expressing GSC cultures are resistant to TMZ, and IC50 (half maximal inhibitory concentration) is estimated at around 500&nbsp;μM. Clonogenic GSC surviving 500&nbsp;μM TMZ (GSC-500&nbsp;μM TMZ), were isolated. Molecular signatures were identified via comparative analysis of expression microarray against parental GSC (GSC-parental). The recombinant protein of top downregulated signature was used as a single agent or in combination with TMZ, for evaluating therapeutic effects of treatment of GSC.ResultsThe molecular signatures characterized an activation of protective stress responses in GSC-500&nbsp;μM TMZ, mainly including biotransformation/detoxification of xenobiotics, blocked endoplasmic reticulum stress-mediated apoptosis, epithelial-to-mesenchymal transition (EMT), and inhibited growth/differentiation. Bone morphogenetic protein 7 (BMP7) was identified as the top down-regulated gene in GSC-500&nbsp;μM TMZ. Although augmenting BMP7 signaling in GSC by exogenous BMP7 treatment did not effectively stop GSC growth, it markedly sensitized both GSC-500&nbsp;μM TMZ and GSC-parental to 35&nbsp;μM TMZ treatment, leading to loss of self-renewal and migration capacity. BMP7 treatment induced senescence of GSC cultures and suppressed mRNA expression of CD133, MGMT, and ATP-binding cassette drug efflux transporters (ABCB1, ABCG2), as well as reconfigured transcriptional profiles in GSC by downregulating genes associated with EMT/migration/invasion, stemness, inflammation/immune response, and cell proliferation/tumorigenesis. BMP7 treatment significantly prolonged survival time of animals intracranially inoculated with GSC when compared to those untreated or treated with TMZ alone (p = 0.0017), whereas combination of two agents further extended animal survival compared to BMP7 alone (p = 0.0489).ConclusionsThese data support the view that reduced endogenous BMP7 expression/signaling in GSC may contribute to maintained stemness, EMT, and chemoresistant phenotype, suggesting that BMP7 treatment may provide a novel strategy in combination with TMZ for an effective treatment of glioblastoma exhibiting unmethylated MGMT

Ribosomal Proteins RPS11 and RPS20, Two Stress-Response Markers of Glioblastoma Stem Cells, Are Novel Predictors of Poor Prognosis in Glioblastoma Patients.

Glioblastoma stem cells (GSC) co-exhibiting a tumor-initiating capacity and a radio-chemoresistant phenotype, are a compelling cell model for explaining tumor recurrence. We have previously characterized patient-derived, treatment-resistant GSC clones (TRGC) that survived radiochemotherapy. Compared to glucose-dependent, treatment-sensitive GSC clones (TSGC), TRGC exhibited reduced glucose dependence that favor the fatty acid oxidation pathway as their energy source. Using comparative genome-wide transcriptome analysis, a series of defense signatures associated with TRGC survival were identified and verified by siRNA-based gene knockdown experiments that led to loss of cell integrity. In this study, we investigate the prognostic value of defense signatures in glioblastoma (GBM) patients using gene expression analysis with Probeset Analyzer (131 GBM) and The Cancer Genome Atlas (TCGA) data, and protein expression with a tissue microarray (50 GBM), yielding the first TRGC-derived prognostic biomarkers for GBM patients. Ribosomal protein S11 (RPS11), RPS20, individually and together, consistently predicted poor survival of newly diagnosed primary GBM tumors when overexpressed at the RNA or protein level [RPS11: Hazard Ratio (HR) = 11.5, p&lt;0.001; RPS20: HR = 4.5, p = 0.03; RPS11+RPS20: HR = 17.99, p = 0.001]. The prognostic significance of RPS11 and RPS20 was further supported by whole tissue section RPS11 immunostaining (27 GBM; HR = 4.05, p = 0.01) and TCGA gene expression data (578 primary GBM; RPS11: HR = 1.19, p = 0.06; RPS20: HR = 1.25, p = 0.02; RPS11+RPS20: HR = 1.43, p = 0.01). Moreover, tumors that exhibited unmethylated O-6-methylguanine-DNA methyltransferase (MGMT) or wild-type isocitrate dehydrogenase 1 (IDH1) were associated with higher RPS11 expression levels [corr (IDH1, RPS11) = 0.64, p = 0.03); [corr (MGMT, RPS11) = 0.52, p = 0.04]. These data indicate that increased expression of RPS11 and RPS20 predicts shorter patient survival. The study also suggests that TRGC are clinically relevant cells that represent resistant tumorigenic clones from patient tumors and that their properties, at least in part, are reflected in poor-prognosis GBM. The screening of TRGC signatures may represent a novel alternative strategy for identifying new prognostic biomarkers