Effects of YouTube Video as Pre-Lecture Preparation

Classroom lectures convey course concepts more effectively when students have prepared in advance. Traditionally, students prepare for lectures by reading the course textbook. Textbooks are the default study material for most educational courses; however, some technical subjects are better conveyed in video format. Therefore, in this study, we encouraged students to supplement their learning resources with web-based video tutorials that provide detailed demonstrations with the respect to technical network configuration and management. YouTube is a video sharing website that can provide free educational tutorials and instructions on technical subject matter, where students can observe practical human-machine interaction to prepare for lectures and increase overall course performance on exams, assignments, and laboratory projects. Our goal was to compare the overall performance as well as the level of active class participation between two groups of the same computer networking course. We found that the group that used YouTube videos for pre-lecture preparation scored approximately 3% higher on exams but 5% lower on homework assignments than the control group (textbook only). There was no statistical significance between the two groups with respect to overall course grades. Study habits and degree of class participation of each student correlated more strongly with overall course performance than whether the student viewed the videos

ROV-based Tracking of a Shallow Water Nocturnal Squid

This paper describes the use of a Remotely Operated Vehicle (ROV) equipped with a monocular vision system to find and track the squid Euprymna scolopes, so that motion behaviors of the squid could be characterized through the use of off-line image processing and state estimation. The ROV was deployed for several nights at several nearshore locations off Oahu, resulting in 10 hours of squid footage. Using blob-tracking image processing techniques and a Particle Filter state estimator, the squid can be detected and tracked. The position, velocity, and acceleration of the squid relative to the stationary ROV can be determined. Experiment results from tracking a simulated squid at known positions in a swimming pool and tracking of live squid in the ocean validate the performance of the tracking system. Results show the 3-D trajectory of the squid in a test feeding video. To the best of the authors’ knowledge, this is the first observatio

Cryogenic STM in 3D vector magnetic fields realized through a rotatable insert

We acknowledge funding from EPSRC (EP/L505079/1 and EP/I031014/1).Spin-polarized scanning tunneling microscopy (SP-STM) performed in vector magnetic fields promises atomic scale imaging of magnetic structure, providing complete information on the local spin texture of a sample in three dimensions. Here, we have designed and constructed a turntable system for a low temperature STM which in combination with a 2D vector magnet provides magnetic fields of up to 5 T in any direction relative to the tip-sample geometry. This enables STM imaging and spectroscopy to be performed at the same atomic-scale location and field-of-view on the sample, and most importantly, without experiencing any change on the tip apex before and after field switching. Combined with a ferromagnetic tip, this enables us to study the magnetization of complex magnetic orders in all three spatial directions.PostprintPeer reviewe

Probing magnetic exchange interactions with helium

Funding: CT and PW acknowledge support from EPSRC (EP/R031924/1) and CMY and LSF from EP/S005005/1. C.H. acknowledges support by the Austrian Science Fund (FWF) Project No. P32144-N36 and the VSC-4 of the Vienna University of Technology. The work was partially supported by the Deutsche Forschungsgemeinschaft (DFG) through Transregional Research Collaboration TRR 80 (Augsburg, Munich, and Stuttgart).Controlling and sensing spin-polarization of electrons forms the basis of spintronics. Here, we report a study of the effect of helium on the spin-polarization of the tunneling current and magnetic contrast in spin-polarized Scanning Tunneling Microscopy. We show that the magnetic contrast in SP-STM images recorded in the presence of helium depends sensitively on the tunneling conditions. From tunneling spectra and their variation across the atomic lattice we establish that the helium can be reversibly ejected from the tunneling junction by the tunneling electrons. The energy of the tunneling electrons required to eject the helium depends on the relative spin-polarization of the tip and sample, making the microscope sensitive to the magnetic exchange interactions. We show that the time-averaged spin polarization of the tunneling current is suppressed in the presence of helium and thereby demonstrate voltage control of the spin polarization of the tunneling current across the tip-sample junction.PostprintPeer reviewe

Finite Element Analysis of Reinforced Concrete Beams with Corrosion Subjected to Shear

Finite element (FE) modeling techniques were developed to isolate the different contributions of corrosion damage to structural response of experimental reinforced concrete beams with shear-dominated behavior. Corrosion-damage parameters included concrete cover spalling due to the expansion of corrosion products; uniform stirrup cross-sectional loss from corrosion; localized stirrup cross-sectional loss due to pitting; debonding of corrosion-damaged stirrups from the concrete. FE analyses were performed including both individual and combined damages. The FE results matched experimental results well and quantitatively estimated capacity reduction of the experimental specimens

The Interstellar Medium and Star Formation in Edge-On Galaxies. I. NGC 891

We analyze images of BIMA 12CO (J = 1 --> 0), VLA HI, and Spitzer 3.6 and 24 \mum emission toward the edge-on galaxy NGC 891 and derive the radial and vertical distributions of gas and the radial distributions of stellar mass and recent star formation. We describe our method of deriving radial profiles for edge-on galaxies, assuming circular motion, and verify basic relationships between star formation rate and gas and stellar content, and between the molecular-to-atomic ratio and hydrostatic midplane pressure, that have been found in other galaxy samples. The Schmidt law index we find for the total gas (H2 + H I) is 0.85\pm0.55, but the Schmidt law provides a poor description of the SFR in comparison to a model that includes the influence of the stellar disk. Using our measurements of the thickness of the gas disk and the assumption of hydrostatic equilibrium, we estimate volume densities and pressures as a function of radius and height in order to test the importance of pressure in controlling the {\rho}H2/{\rho}HI ratio. The gas pressure in two dimensions P(r, z) using constant velocity dispersion does not seem to correlate with the {\rho}H2/{\rho}HI ratio, but the pressure using varying velocity dispersion appears to correlate with the ratio. We test the importance of gravitational instability in determining the sites of massive star formation, and find that the Q parameter using a radially varying gas velocity dispersion is consistent with self-regulation (Q - 1) over a large part of the disk.Comment: 19 pages, 19 figures, accepted for publication in A

Quinazoline-Based Antivirulence Compounds Selectively Target Salmonella PhoP/PhoQ Signal Transduction System

The rapid emergence of multidrug resistance among bacterial pathogens has become a significant challenge to human health in our century. Therefore, development of next-generation antibacterial compounds is an urgent need. Two-component signal transduction systems (TCS) are stimulus-response coupling devices that allow bacteria to sense and elaborate adaptive responses to changing environmental conditions, including the challenges that pathogenic bacteria face inside the host. The differential presence of TCS, present in bacteria but absent in the animal kingdom, makes them attractive targets in the search for new antibacterial compounds. In Salmonella enterica, the PhoP/PhoQ two-component system controls the expression of crucial phenotypes that define the ability of the pathogen to establish infection in the host. We now report the screening of 686 compounds from a GlaxoSmithKline published kinase inhibitor set in a high-throughput whole-cell assay that targets Salmonella enterica serovar Typhimurium PhoP/PhoQ. We identified a series of quinazoline compounds that showed selective and potent downregulation of PhoP/PhoQ-activated genes and define structural attributes required for their efficacy. We demonstrate that their bioactivity is due to repression of the PhoQ sensor autokinase activity mediated by interaction with its catalytic domain, acting as competitive inhibitors of ATP binding. While noncytotoxic, the hit molecules exhibit antivirulence effect by blockage of S. Typhimurium intramacrophage replication. Together, these features make these quinazoline compounds stand out as exciting leads to develop a therapeutic intervention to fight salmonellosis.Fil: Carabajal, María Ayelén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Asquith, Christopher R. M.. University of North Carolina; Estados UnidosFil: Laitinen, Tuomo. University of North Carolina; Estados UnidosFil: Tizzard, Graham J.. University of North Carolina; Estados UnidosFil: Yim, Lucía. Universidad de la República; UruguayFil: Rial, Analía. Universidad de la República; UruguayFil: Chabalgoity, José A.. Universidad de la República; UruguayFil: Zuercher, William J.. University of North Carolina; Estados UnidosFil: Garcia Vescovi, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Overview of NASA GRCs Green Propellant Infusion Mission Thruster Testing and Plume Diagnostics

The Green Propellant Infusion Mission (GPIM) is sponsored by NASA's Space Technology Mission Directorate (STMD) Technology Demonstration Mission (TDM) office. The goal of GPIM is to advance the technology readiness level of a green propulsion system, specifically, one using the monopropellant, AF-M315E, by demonstrating ground handling, spacecraft processing, and on-orbit operations. One of the risks identified for GPIM is potential contamination of sensitive spacecraft surfaces from the effluents in the plumes of AF-M315E thrusters. NASA Glenn Research Center (GRC) is conducting activities to characterize the effects of AF-M315E plume impingement and deposition. GRC has established individual plume models of the 22-N and 1-N thrusters that will be used on the GPIM spacecraft. The models describe the pressure, temperature, density, Mach number, and species concentration of the AF-M315E thruster exhaust plumes. The models are being used to assess the impingement effects of the AF-M315E thrusters on the GPIM spacecraft. The model simulations will be correlated with plume measurement data from Laboratory and Engineering Model 22-N, AF-M315E thrusters. The thrusters will be tested in a small rocket, altitude facility at NASA GRC. The GRC thruster testing will be conducted at duty cycles representatives of the planned GPIM maneuvers. A suite of laser-based diagnostics, including Raman spectroscopy, Rayleigh spectroscopy, Schlieren imaging, and physical probes will be used to acquire plume measurements of AFM315E thrusters. Plume data will include temperature, velocity, relative density, and species concentration. The plume measurement data will be compared to the corresponding simulations of the plume model. The GRC effort will establish a data set of AF-M315E plume measurements and a plume model that can be used for future AF-M315E applications

Blood-brain barrier permeability in survivors of immune-mediated thrombotic thrombocytopenic purpura: A pilot study

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder of systemic microthrombosis and organ ischemia. The etiology of chronic cerebrovascular outcomes in iTTP survivors is largely unknown. In this pilot study, we measured blood-brain barrier (BBB) permeability in patients with iTTP at the start of remission and 6 months later. This prospective pilot study included 7 adult patients with incident iTTP. Eligibility criteria included ADAMTS13 activity, 10% and detectable inhibitor at diagnosis. Patients were recruited from London Health Sciences Centre in Canada (2017-2019) within 3 days of hospital admission and followed for 6 months after remission (defined as normalization of platelet count and lactate dehydrogenase with no clinical signs or symptoms of microvascular injury for more than 30 days after the last plasma exchange). All patients had cerebral computed tomography perfusion scans with BBB permeability surface product measurements. Patients (5 women, 2 men) had a mean age of 48 years (range, 21-77 years). At diagnosis, patients had a mean platelet count of 22 (standard deviation [SD], 25) 3 109/L. At the start of remission, mean BBB permeability surface product was 0.91 (0.30) mL/min/100 g. Six months later, the mean permeability surface product was 0.56 (0.22) mL/min/100 g, with a mean difference of 20.312 mL/min/100 g (95% confidence interval: 20.4729 to 20.1510; P 5.0032). In this pilot study of patients with iTTP, pathologically increased BBB permeability was evident, and although there was some improvement, this persisted 6 months after remission. Future work will explore the chronicity of these findings and their clinical implications

Ethnic disparity and exposure to supplements rather than adverse childhood experiences linked to preterm birth in Pakistani women

Background: Adverse childhood experiences (ACEs) are associated with prenatal mental health and negative pregnancy outcomes in high income countries, but whether the same association exists in Pakistan, a low- to middle-income (LMI) country, remains unclear. Methods: Secondary data analyses of a prospective longitudinal cohort study examining biopsychosocial measures of 300 pregnant women at four sites in Karachi, Pakistan. A predictive multiple logistic regression model for preterm birth (PTB; i.e., \u3c37 weeks’ gestation) was developed from variables significantly (P \u3c 0.05) or marginally (P \u3c 0.10) associated with PTB in the bivariate analyses. Results: Of the 300 women, 263 (88%) returned for delivery and were included in the current analyses. The PTB rate was 11.1%. We found no association between ACE and PTB. Mother\u27s education (P = 0.011), mother\u27s ethnicity (P = 0.010), medications during pregnancy (P = 0.006), age at birth of first child or current age if primiparous (P = 0.049) and age at marriage (P = 0.091) emerged as significant in bivariate analyses. Mother\u27s ethnicity and taking medications remained predictive of PTB in the multivariate model. Limitations: Findings are limited by the relatively small sample size which precludes direct testing for possible interactive effects. Conclusions: In sum, pathways to PTB for women in LMI countries may differ from those observed in highincome countries and may need to be modelled differently to include behavioural response to emotional distress and socio-cultural contexts