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COVID-19 has caused drastic changes to almost all aspects of daily life, with education being the center of these changes and concerns. In particular, teaching approaches have been rapidly reoriented to online versions. Although there is a growing body of literature exploring the views of education during this crisis, a critical need exists to document challenges confronting educators in online teaching. In this paper, we explore the online teaching barriers and motivations of 55 in-service teachers in the Philippines, and how these variables contributed to their perceptions of stress regarding online teaching immediately after the pandemic started. Results demonstrated that respondents’ perceptions of interest in online teaching significantly reduced their perceptions of stress regarding online teaching. However, barriers to online teaching, online communication self-efficacy, and the utility value of online teaching perceived by respondents positively predicted their perceptions of stress regarding online teaching. Furthermore, this paper discusses the future perspectives of online teaching transformation based on expectancy value and self-efficacy theories. Especially, the findings of this paper provide a first look at the stress mechanisms of in-service teachers and initial information regarding stress reduction and professional development of in-service teachers in online teaching.

Self-efficacy is easily the most important construct for engagement and success in achievement contexts. In this article, we aim to promote a better understanding of theory-driven practices that fo...

PurposeGrounded in hydrodynamic theory, proximal isovelocity surface area (PISA) is a simplistic and practical technique widely used to quantify valvular regurgitation flow. PISA provides a relatively reasonable, though slightly underestimated flow rate for circular orifices. However, for elliptical orifices frequently seen in functional mitral regurgitation, PISA underestimates the flow rate. Based on data obtained with computational fluid dynamics (CFD) and in vitro experiments using systematically varied orifice parameters, we hypothesized that flow rate underestimation for elliptical orifices by PISA is predictable and within a clinically acceptable range.MethodsWe performed 45 CFD simulations with varying orifice areas 0.1, 0.3 and 0.5 cm2, orifice aspect ratios 1:1, 2:1, 3:1, 5:1, and 10:1, and peak velocities (Vmax) 400, 500 and 600 cm/s. The ratio of computed effective regurgitant orifice area to true effective area (EROAC/EROA) against the ratio of aliasing velocity to peak velocity (VA/Vmax) was analyzed for orifice shape impact. Validation was conducted with in vitro imaging in round and 3:1 elliptical orifices.ResultsPlotting EROAC/EROA against VA/Vmax revealed marginal flow underestimation with 2:1 and 3:1 elliptical axis ratios against a circular orifice (A/Vmax), rising to ≤35% for 10:1 ratio. In vitro modeling confirmed CFD findings; there was a 8.3% elliptical EROA underestimation compared to the circular orifice estimate.ConclusionPISA quantification for regurgitant flow through elliptical orifices produces predictable, but generally small, underestimation deemed clinically acceptable for most regurgitant orifices.

Grounded in hydrodynamic theory, proximal isovelocity surface area (PISA) is a simplistic and practical technique widely used to quantify valvular regurgitation flow. PISA provides a relatively reasonable, though slightly underestimated flow rate for circular orifices. However, for elliptical orifices frequently seen in functional mitral regurgitation, PISA underestimates the flow rate. Based on data obtained with computational fluid dynamics (CFD) and in vitro experiments using systematically varied orifice parameters, we hypothesized that flow rate underestimation for elliptical orifices by PISA is predictable and within a clinically acceptable range. We performed 45 CFD simulations with varying orifice areas 0.1, 0.3 and 0.5 cm

Graphical abstract, Highlights • Angle correction may be needed when PISA is applied to a near commissural MR jet. • Four-dimensional flow MRI enabled MR volume quantification with 3D jet visualization. • Exercise-induced VT may have complex structural, genetic, and ECG etiologies.

PURPOSE: This study investigated the impact of bicuspid aortic valve (BAV) on valve morphology and motion as well as proximal and aortic hemodynamics using a same-day echocardiography and cardiac MRI. METHODS: Transthoracic echocardiography, two-dimensional cine MRI of the aortic valve, and aortic 4D flow MRI were performed on the same day in 9 normofunctional BAV patients (age=41±12, 3 female), 4 BAV with moderate to severe aortic stenosis (AS) (age=63±5, 1 female), and 36 healthy tricuspid aortic valve controls (age=52±10, 21 female). Valve opening and closing timings and transvalvular peak velocity were measured using B-mode and Doppler echocardiogram, respectively. Valve orifice morphology at fully-opened state was characterized using cine MRI. Ascending aortic (AAo) wall shear stress (WSS) was measured using 4D flow MRI data. RESULTS: Valve motion timings were similar between BAV and controls. BAV was associated with increased orifice aspect ratio (1.44±0.11 vs. 1.10±0.13, PCONCLUSION: A same-day echo and MRI imaging allows for comprehensive assessment of the impact of aortic valve disease on valve function and hemodynamics. In this pilot application to BAV, we found increased orifice aspect ratio may be responsible for increased transvalvular peak velocity and maximum AAo WSS.

Aim For dosimetry in radioligand therapy, the time-integrated activity coefficients (TIACs) for organs at risk and for tumour lesions have to be determined. The used sampling scheme affects the TIACs and therefore the calculated absorbed doses. The aim of this work was to develop a general and flexible method, which analyses numerous clinically applicable sampling schedules using true time-activity curves (TACs) of virtual patients. Method Nine virtual patients with true TACs of the tumours were created using a physiologically-based pharmacokinetic (PBPK) model and individual biokinetic data of five patients with neuroendocrine tumours and four with meningioma. 111 In-DOTATATE was used for pre-therapeutic dosimetry. In total, 15,120 sampling schemes, each consisting of 4 time points, were investigated. Gaussian noise of different levels was added to the corresponding true time-activity points. A bi-exponential function was used to fit the simulated time-activity data. For each investigated sampling schedule, 1000 replications were performed. Patient-specific and population-specific optimal sampling schedules were determined using the relative root-mean-square error ( rRMSE). Furthermore, the fractions of TIACs a ˜ deviating >5% ( f Δ a ˜ > 5 % ) and >10% ( f Δ a ˜ > 10 % ) from the true TIAC a ˜ true were used for additional evaluations e.g. to investigate the effect of varying single time points. Results Almost all patient-specific and all population-specific optimal sampling schedules have t4 ≥ 96 h for all noise levels. Changing the latest time point from the population-specific optimal time to e.g. 48 h leads to a median increase of f Δ a ˜ > 10 % from 0.1% to 88% for the lowest investigated noise level. Using the determined population-specific optimal schedules, results in more accurate and precise results than established schedules from the literature. Conclusion A method of determining the optimal sampling schedule for dosimetry, which considers clinical working hours and measurement uncertainties, has been developed and applied. The simulation study shows that optimised sampling schedules result in high accuracy and precision of the determined TIACs.

This study aims to systematically verify if the simplified geometry and flow profile of the left ventricular outflow tract (LVOT) assumed in 2D echocardiography is appropriate while examining the utility of 4D flow MRI to assess valvular disease. This prospective study obtained same-day Doppler echocardiography and 4D flow MRI in 37 healthy volunteers (age: 51.9 ± 18.2, 20 females) and 7 aortic stenosis (AS) patients (age: 64.2 ± 9.6, 1 female). Two critical assumptions made in echocardiography for aortic valve area assessment were examined, i.e. the assumption of (1) a circular LVOT shape and (2) a flat velocity profile through the LVOT. 3D velocity and shape information obtained with 4D flow MRI was used as comparison. It was found that the LVOT area was lower (by 26.5% and 24.5%) and the velocity time integral (VTI) was higher (by 28.5% and 30.2%) with echo in the healthy and AS group, respectively. These competing errors largely cancelled out when examining individual and cohort averaged LVOT stroke volume. The LVOT area, VTI and stroke volume measured by echo and 4D flow MRI were 3.6 ± 0.7 vs. 4.9 ± 1.0 cm

PURPOSE The purpose of this study was to evaluate the accuracy of four-dimensional (4D) flow MRI for direct assessment of peak velocity, flow volume, and momentum of a mitral regurgitation (MR) flow jets using an in vitro pulsatile jet flow phantom. We systematically investigated the impact of spatial resolution and quantification location along the jet on flow quantities with Doppler ultrasound as a reference for peak velocity. METHODS Four-dimensional flow MRI data of a pulsatile jet through a circular, elliptical, and 3D-printed patient-specific MR orifice model was acquired with varying spatial resolution (1.5-5 mm isotropic voxel). Flow rate and momentum of the jet were quantified at various axial distances (x = 0-50 mm) and integrated over time to calculate Voljet and MTIjet . In vivo assessment of Voljet and MTIjet was performed on 3 MR patients. RESULTS Peak velocities were comparable to Doppler ultrasound (3% error, 1.5 mm voxel), but underestimated with decreasing spatial resolution (-40% error, 5 mm voxel). Voljet was similar to regurgitant volume (RVol) within 5 mm, and then increased linearly with the axial distance (19%/cm) because of flow entrainment. MTIjet remained steady throughout the jet (2%/cm) as theoretically predicted. Four and 9 voxels across the jet were required to measure flow volume and momentum-time-integral within 10% error, respectively. CONCLUSION Four-dimensional flow MRI detected accurate peak velocity, flow rate, and momentum for in vitro MR-mimicking flow jets. Spatial resolution significantly impacted flow quantitation, which otherwise followed predictions of flow entrainment and momentum conservation. This study provides important preliminary information for accurate in vivo MR assessment using 4D flow MRI.

Advances in flow visualization techniques based on optics, such as lasers and digital cameras, have contributed considerably to the development of various flow models. However, the uses of optical techniques for flow visualization in porous media are limited owing to the complexity or opaqueness of the medium. This study demonstrates the utilization of magnetic resonance velocimetry to visualize a flow field in a textile material. By using phase-contrast magnetic resonance imaging, a three-dimensional, three-component velocity vector field was obtained for induced flow through a cut-pile carpet owing to the suction of a vacuum cleaner nozzle. As a result, we were able to experimentally identify the flow-dominant region in the carpet. Specifically, velocity vector plots and flow streamlines facilitated the identification of the flow paths, and indicated that the flow was strongest beneath the narrow walls of the vacuum nozzle. In addition, the pressure field in the carpet was estimated by an omni-directional integral method based on the utilization of the visualized velocity field, which showed where the pressure loss was maximized.

Four-dimensional flow magnetic resonance imaging (4D flow MRI) is a versatile tool to obtain hemodynamic information and anatomic information simultaneously. The wall shear stress (WSS), a force exerted on a vessel wall in parallel, is one of the hemodynamic parameters available with 4D flow MRI and is thought to play an important role in clinical applications such as assessing the development of atherosclerosis. Nevertheless, the accuracy of WSS obtained with 4D flow MRI is rarely evaluated or reported in literature, especially in the in vivo studies. We propose a novel and facile criterion called Reynolds resolution to assess the accuracy of WSS estimation in 4D flow MRI studies. Reynolds resolution consists of a spatial resolution, encoding velocity, kinematic viscosity of a working fluid, and signal-to-noise ratio, which are readily accessible information in 4D flow MRI measurements. We explored the relationship between Reynolds resolution and the WSS error. To include diverse and extensive cases, we measured three circular tubing flows with a diameter of 40, 8, and 2 mm. The 40 mm tubing flow was measured by 3 Tesla (T) human MR scanner with a knee coil and spatial resolution of 0.5 mm. The 8 and 2 mm tubing flows were both measured by 4.7 T MR scanner, but the scans were performed with a conventional birdcage coil (8 mm tubing) and a custom-made solenoid coil (2 mm tubing), respectively. The spatial resolution was varied from 0.2, 0.4 or 0.8 mm for the 8 mm tubing flow, but was fixed at 0.090 mm for 2 mm tubing flow. In addition, the near-wall velocity gradient, required to be determined prior to the WSS, was calculated using two methods; these included assuming a linear velocity profile or quadratic velocity profile near wall. The accuracy of WSS obtained using each method and tubing flow was evaluated against the theoretical WSS value. As a result, we found that Reynolds resolution is in logarithmic relation to the WSS error.

Magnetic resonance velocimetry (MRV) is a versatile flow visualization technique that is used to measure three-component velocity vectors in a 3D space. However, the spatial resolution of MRV is relatively poor in comparison with optical flow visualization techniques, thereby limiting its applicability to small-scale flows and wall shear stress (WSS) estimation. Thus, we built a solenoid RF coil and evaluated its performance in terms of spatial resolution improvement by measuring the laminar flow in a circular tubing. The coil was developed for a 4.7 Tesla MRI system and for tightly wrapping a flow tubing with an inner diameter of 2 mm. The custom-made RF coil could precisely capture the velocity vectors in a voxel that was 11 times smaller than a commercial coil at the same SNR. Therefore, the WSS errors estimated using the custom-made and commercial coils were 8.5 % and 42.3 %, respectively.

Introduction: Relative apical sparing of longitudinal strain (RALS, the ratio of apical strain vs the rest of the heart) on echocardiography has been found to have high sensitivity and specificity for differentiating cardiac amyloidosis (CA) from other causes of left ventricular hypertrophy. Previous studies have shown no significant difference between amyloid subtypes, systemic light-chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) Hypothesis: There will be a significant difference in sensitivity and specificity of RALS to detect CA across amyloid subtypes. Methods: A cohort of patients with either AL or ATTR amyloid was identified, with a control cohort of patients with left ventricular hypertrophy (LVH) of other etiologies. Speckle tracking echocardiography was performed on EchoPAC (GE Medical Systems) software to obtain values of basal, mid, and apical longitudinal strain for each patient; relative apical strain was then calculated. Results: The TTR group (n=22) was older (66.4±7.9, 76.6±11.6, p=0.001) and more likely to be female (p=0.009) than the AL group (n=30), both groups had similar rates of hypertension, diabetes mellitus, and end stage renal disease. Echocardiographic markers of diastolic function were decreased in both groups; the AL group had decreased left ventricle end diastolic volume (60.9±25.5, 94.9±50.2, p=0.012) and mean wall thickness (1.4±0.3, 1.6±0.4 p=0.017). ROC analysis using a RALS cutoff of 2 to differentiate AL and ATTR from the LVH control group revealed similar specificity (AL 85%, ATTR 85%) and sensitivity (AL 40%, ATTR 50%). Difference in area-under-curve (AUC) was not significant (p=0.2) (figure). Conclusions: ATTR and AL amyloid have similar specificity, but ATTR has a trend towards improved sensitivity over AL for detection of CA using RALS with the previously validated threshold of 2. This might become significant with a larger sample, work that is currently on-going..

Introduction: Relative apical longitudinal strain (RALS) is defined as (average apical LS/(average basal & mid-ventricular LS)). A threshold of 2 has been found to have high sensitivity and specificity for differentiating cardiac amyloidosis (CA) from other causes of left ventricular hypertrophy (LVH). This threshold was developed using General Electric (GE) software, and its reproducibility among different software vendors is unknown. Hypothesis: In patients with CA, regional segmental LS patterns and relative apical longitudinal strain will vary among software vendors. Methods: Speckle-tracking echocardiography was retroactively performed by an experienced technician on two patient cohorts, CA (n=52) and LVH (n=52), using software from two independent vendors: EchoPAC (GE Medical Systems) and TomTEC (TOMTEC Imaging Systems GMBH). For each vendor and patient, strain values for the basal, mid, and apical segments were averaged to obtain three regional LS values which were then used to calculate global longitudinal strain (GLS) and RALS. Results: EchoPAC demonstrated greater average apical LS (-16.5±5.7 vs -13.1±6.6, p Conclusions: Software measurements of regional LS and thus RALS vary between vendors. Further efforts are needed for intervendor regional strain fidelity. For now, different RALS thresholds to diagnose CA may be needed for various vendors.

Introduction: 4D flow MRI can assess transvalvular velocity, but validation against continuous wave (CW) Doppler echo is limited in high-velocity regurgitation and stenosis situations. We sought to compare 4D flow MRI and echo peak velocity using a pulsatile echo-MRI flow phantom. Materials and Methods: An MRI-compatible flow phantom with restrictive orifice situated was driven by a left ventricular assist device at 50 bpm (figure 1A). Three orifice shapes were tested: circular, elliptical and 3D-printed patient-specific mitral regurgitant orifice model of prolapse with areas of 0.5, 0.41 and 0.35 cm 2 , respectively. CW Doppler was acquired with peak velocity extracted from the profile. Retrospectively-gated 4D flow MRI was performed (spatial resolution = 2 mm isotropic, temporal resolution = 36 ms, encoding velocity = 400 cm/s). Maximal velocity magnitude was extracted volumetrically (figure 1B). An echo-mimicking profile was also obtained with a “virtual” ultrasound beam in the 4D flow data to simulate CW Doppler (figure 1C). Bland-Altman analysis was used to assess the agreement of temporal peak velocities. Results: 4D flow MRI demonstrated a centrally directed jet for the circular and elliptical orifices and an oblique jet for the prolapse orifice (figure 1B). Peak velocities were in excellent agreement between 4D flow MRI vs. echo for the circular (peak: 5.13 vs. 5.08 m/s, bias = 0.06 ± 0.66 m/s, figure 1D) and the elliptical orifice (peak: 4.95 vs. 4.79 m/s, bias = 0.07 ± 0.87 m/s, figure 1E). The prolapse orifice velocity was underestimated somewhat by MRI by ~10% (peak: 4.41 vs. 4.90 m/s, bias=0.26±1.18, figure 1F). Conclusion: 4D flow MRI can quantify high velocities like echo for simple geometries while underestimating for more complex geometry, likely due to partial volume effects. Further investigation is warranted to systematically investigate the effects of 4D flow MRI spatial and temporal resolution as well as the jet angle on velocity quantification accuracy.

PURPOSE This study used a 5D flow framework to explore the influence of arrhythmia on thrombogenic hemodynamic parameters in patients with atrial fibrillation (AF). METHODS A fully self-gated, 3D radial, highly accelerated free-running 5D flow sequence with interleaved four-point velocity-encoding was acquired using an in vitro arrhythmic flow phantom and in 25 patients with a history of AF (68 ± 8 y, 6 female). Self-gating signals were used to calculate AF burden, bin data, and tag each k-space line with its RRLength . Data were binned as an RR-resolved dataset with four RR-interval bins (RR1-RR4, short-to-long) for compressed sensing reconstruction. AF burden was calculated as interquartile range of all intrascan RR-intervals divided by median RR-interval, and left atrial (LA) stasis as the percent of the cardiac cycle where the velocity was

BACKGROUND Four-dimensional (D) flow magnetic resonance imaging (MRI) is limited by time-consuming and nonstandardized data analysis. We aimed to test the efficiency and interobserver reproducibility of a dedicated 4D flow MRI analysis workflow. MATERIALS AND METHODS Thirty retrospectively identified patients with bicuspid aortic valve (BAV, age=47.8±11.8 y, 9 male) and 30 healthy controls (age=48.8±12.5 y, 21 male) underwent Aortic 4D flow MRI using 1.5 and 3 T MRI systems. Two independent readers performed 4D flow analysis on a dedicated workstation including preprocessing, aorta segmentation, and placement of four 2D planes throughout the aorta for quantification of net flow, peak velocity, and regurgitant fraction. 3D flow visualization using streamlines was used to grade aortic valve outflow jets and extent of helical flow. RESULTS 4D flow analysis workflow time for both observers: 5.0±1.4 minutes per case (range=3 to 10 min). Valve outflow jets and flow derangement was visible in all 30 BAV patients (both observers). Net flow, peak velocity, and regurgitant fraction was significantly elevated in BAV patients compared with controls except for regurgitant fraction in plane 4 (91.1±29.7 vs. 62.6±19.6 mL/s, 37.1% difference; 121.7±49.7 vs. 90.9±26.4 cm/s, 28.9% difference; 9.3±10.1% vs. 2.0±3.4%, 128.0% difference, respectively; P

Carotid endarterectomy (CEA) influences the carotid endoluminal anatomy, which results in hemodynamic changes before and after surgery. We investigated the hemodynamics of severe carotid artery stenosis before and after conventional endarterectomy with/without patch repair. An in vitro experiment utilizing carotid phantoms, which underwent a procedure that emulated CEA with/without the patch repair, was performed with a high-spatiotemporal resolution using 4D flow MRI. We evaluated an abnormal region of carotids, which consists of the normalized time-averaged wall shear stress (NTA|WSS|) and the oscillatory shear index (OSI), to account for continuous high-shear regions (high NTA|WSS| and low OSI) and chaotic low-shear regions, i.e., stenosis-prone regions (low NTA|WSS| and high OSI). The use of normalized hemodynamic parameters (e.g., NTA|WSS|) allowed comparison of diverse cases with different conditions of hemodynamics and vessel geometry. We observed that the stenosis-prone regions of the carotids with patches were noticeably larger than the corresponding regions in no-patch carotids. A large recirculating flow zone found in the stenosis-prone region of the internal carotid artery (ICA) of the postoperative carotids with patches partially blocks the flow path into ICA, and consequently the flow rate was not recovered after surgery unlike an expectation.

We tested the effectiveness of the intervention program designed to enhance children's math motivation by simultaneously strengthening their growth mindsets and weakening their gender stereotypes. Both the intervention and control programs consisted of six bi-weekly 40-min sessions that were evenly distributed over three months and administered during regular school hours. Repeated measures analyses of variance with group (between-subject factor: intervention vs. control) and time (within-subject factor: pretest vs. posttest) revealed significant Group × Time interactions for all outcomes but test anxiety. Growth mindset, perceived competence, persistence, and achievement of the intervention group increased, while those of the control group decreased. Gender stereotypic beliefs exhibited the opposite pattern. Also, growth mindset and gender stereotypes correlated negatively only for the intervention group. Path analysis demonstrated that the growth mindset of students after the intervention predicted their math persistence and achievement directly and indirectly via their perceived competence in math.

Magnetic resonance velocimetry (MRV) is a versatile flow visualization technique that has been utilized for medical applications. Recently, MRV has been used to visualize engineering flows, but most engineers are still unfamiliar with the technique. In this paper, we introduce the basic principles and experimental configurations of MRV in detail and evaluate the accuracy of MRV applied to measure the mean velocity fields of turbulent flows in a circular pipe. A Philips Achieva 3.0 T Tx MRI scanner is used to provide a magnetic field and acquire resonance signals for flow visualization. Fully developed turbulent flows with Reynolds numbers of 6800, 9900 and 19400 were measured, and the axial mean velocity vectors were obtained with a spatial resolution of 0.5 mm for the three directions. Results show that the mean velocity profiles are in good agreement with reference data sets when properly scaled in both the inner and outer layers.

We present an automatic method to estimate flow rate through the orifice in in-vitro 2D color-flow Doppler echocardiographic images. Flow rate properties are important for the assessment of pathologies like mitral regurgitation. We expect this method to be transferable to in-vivo patient data. The method consists of two main parts: (a) detecting a bounding box which encloses aliasing contours and its surroundings (namely a region representative of flow convergence area), (b) application of Convolutional Neural Networks for regression to estimate the flow convergence area. Best result achieved is the 5% mean error for validation data which is from other experiments that were used for training. Given the small number of training data, this method shows promising results.

To explore the feasibility of using four-dimensional (4D) flow MRI to quantify blood flow and kinetic energy (KE) in the heart during strenuous exercise.For this prospective study, cardiac 4D flow MRI was performed in 11 healthy young adult participants (eight men, three women; mean age, 26 years ± 1 [standard deviation]) at rest and during exercise with an MRI-compatible exercise stepper between March 2016 and July 2017. Flow was measured in the ascending aorta (AAo) and main pulmonary artery (MPA). KE was quantified in the left and right ventricle. Significant changes in flow and KE during exercise were identified by usingNine participants successfully completed both rest and exercise imaging. Internal flow consistency analysis in systemic and pulmonary circulation showed average relative differences of 10% at rest and 16% during exercise. For flow measurements in the AAo and MPA, relative differences between observers never exceeded 6% in any vessel and showed excellent correlation, even during exercise. Relative differences were increased for KE, typically on the order of 30%, with poor interobserver correlation between measurements.Four-dimensional flow MRI can quantify increases in flow in the AAo and MPA during strenuous exercise and is highly repeatable. KE had reduced repeatability because of suboptimal segmentation methods and requires further development before clinical implementation.

Drawing upon expectancy-value theory ( Eccles et al., 1983 ), we aimed to test the cross-cultural validity of scales for assessing adolescent students' values and costs in Germany, China, and Korea with a focus on gender and age differences and the potential cross-cultural generalizability of the structural relations. In each country (N = 483 in Germany, N = 598 in China, and N = 617 in Korea), we assessed students' self-efficacy, values, and costs in math and English using the same questionnaires. Within each country, the scales showed evidence of strong measurement invariance across both gender and age, and there were gender and age differences in the mean levels of values and costs. Weak measurement invariance was shown across countries. The structural relations among self-efficacy, values, and costs were very similar across the two academic subjects within each country, whereas there were slight differences between countries.

We developed the real-time analysis of chemotactic motion of microbial cells (Euglena gracilis), for on-chip cytotoxicity sensing for environmental chemical substances. TheEuglenacells were confined in a closed-type micro-aquarium in a PDMS microchip, and their movements were taken by a CMOS video camera. When 1.5%-H2O2was introduced into a microchannel running aside of the micro-aquarium, the H2O2molecules permeated into the micro-aquarium by diffusion through porous PDMS wall, and the cells fell into continuous rotation instead of single step turning and/or straightforward swimming. Such an abnormal swimming behavior is the result of metabolic disturbing effects evoked by radical oxygen species released from H2O2. In order to sensing the metabolic disturbing effects, we achieved real-time categorization of the swimming traces into straightforward swimming or continuous rotation; firstly the swimming traces in the video image were sectioned into squares, and then the aspect ratio and filling factor for each square were calculated. High aspect ratio or small filling factor corresponded to straightforward swimming, whereas low aspect ratio and high filling factor to continuous rotation. This motion analysis enables to measure the metabolic disturbing effects on swimmingEuglenacells quantitatively, which is important to detect unidentified toxic substances in environments.

We found that the transient freezing behavior in photophobic responses of Euglena gracilis is a good indicator of the metabolic status of the cells. The transient blue light photophobic responses of E. gracilis cells were investigated on-chip using a new measurement, 'trace momentum' (TM), to evaluate their swimming activity quantitatively in real time. When blue light of intensity >30 mW cm(-2) was repeatedly switched on and off, a large negative spike in the TM was observed at the onset of the 'blue-light-off' phase. Single-cell trace analysis at a blue light intensity of 40 mW cm(-2) showed that 48% (on average, n = 15) of tumbling Euglena cells ceased activity ('freezing') for 2-30 s at the onset of blue-light-off before commencing forward motion in a straight line (termed 'straightforward swimming'), while 45% smoothly commenced straightforward swimming without delay. The proportion of freezing Euglena cells depended on the blue light intensity (only 20% at 20 mW cm(-2)). When the cells were stimulated by four blue light pulses at the higher intensity, without pre-exposure, the transient freezing behavior was more prominent but, on repeating the stimuli after an 80 min interval in red light, the same cells did not freeze. This shows that the metabolism of the cells had changed to anti-freezing during the interval. The relationship between the interval time with/without light irradiation and the blue light adaptation was elucidated experimentally. The origin of the freezing behavior is considered to be a shortage of a metabolic substance that promotes smooth switching of flagellum movement from in situ rotation mode to a straightforward swimming mode.

On-chip cytotoxicity sensing for liquid substances was investigated by using the microbial chemotaxis of Euglena gracilis. The Euglena cells were confined in a closed-type micro-aquarium in a PDMS microchip, and the micro-aquarium was isolated from two microchannels to flow test and reference liquid substances. Small molecules of liquids permeated into PDMS and diffused into the water in the micro-aquarium, and thus, the chemical concentration gradient of test liquids was built in the micro-aquarium. The negative chemotactic movements of Euglena cells were observed for ethanol down to 0.5% within 2-5 min after the injection of diluted ethanol into one of the separated microchannels (counter reference = pure water). On the other hand, when 0.5% H2O2was introduced as a test liquid (counter reference = pure water), the Euglena cells fell into continuous rotation instead of single step turning and/or straight forward swimming. As a result, total swimming activity in the micro-aquarium decreased even after H2O2flow was switched back to water. The observation shows that the types of cytotoxic effects can be identified through the cell movement analysis.

We tested the interaction between task value and self-efficacy on defensive pessimism, academic cheating, procrastination and self-handicapping among 574 Korean 11th graders in the context of English as a foreign language. We hypothesised that perceiving high value in tasks or domains for which self-efficacy was low would pose a threat to perceived self-worth, leading students to resort to various maladaptive achievement strategies. Hierarchical multiple regression analyses demonstrated that, consistent with our hypothesis, the relationships of task value with academic cheating and procrastination depended on the level of self-efficacy. Perceiving high intrinsic value positively predicted academic cheating for students with low self-efficacy but not for students with high self-efficacy. Likewise, perceiving intrinsic or utility value positively predicted procrastination for students with low self-efficacy but not for students with high self-efficacy. Our findings support the major tenets of self-worth theory.

We investigated on-chip cytotoxicity gas sensing using the bacterial chemotaxis of Euglena confined in a microaquarium. The sensor chip made from PDMS had one microaquarium and two microfluidic channels passing aside of the microaquarium. The chemotactic microbial cells were confined in the microaquarium, whereas two gases (one sample and one reference) flowed in the two isolated microchannels. Gas molecules move from the microchannels into the microaquarium by permeation through porous PDMS wall, and dissolve into the water in the microaquarium, where Euglena cells are swimming. The chemotactic movements of Euglena were observed with an optical microscope and measured as traces in real time. By injecting CO2 and air into each microchannel separately, the Euglena cells in the microaquarium moved to air side, escaping from CO2. This observation showed that the concentration gradient of CO2 was produced in the water in the microaquarium. The CO2-avoiding movement of Euglena was increased largely at a CO2 concentration of 40%, and then moderately increased above 60%. Some Euglena cells stopped swimming at the air side of the microaquarium and remained there even after CO2 has been removed, which can be used as the indicator of CO2 history.

Using living microbial cells in computational processing is a fascinating challenge to incorporate their autonomous adaptation and exploration abilities into a physical computing algorithm [1]. When the stimulus to the cells is given as analog values, more flexible solutions would be expected in microbe-based neurocomputing [1] owing to the diversity of reaction threshold among the cells. We have investigated the optical analog feedback in Euglena-based neurocomputing, for a task to select some from 16 compartments with avoiding the first and second nearest compartments [2].

Polydiacetylene (PDA), conjugated polymer, is an attractive sensor material that has a unique optical property to transform its color from visible blue to fluorescent red upon environmental perturbations like heat, pH, specific metal ions, and etc. In this study, we propose a novel method to detect metal ions by using polydiacetylene (PDA)-embedded sensor microfibers fabricated with a 3-D hydrodynamic focusing technique using alginate and calcium solutions. Moreover, by changing the head groups of PDA, we successfully detected Al3+ and Zn2+ ions up to 1mM using PDA micro fibers.Copyright © 2011 by KSME