267 research outputs found

    Motivating Studentsā€™ STEM Learning Using Biographical Information

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    Science instruction has focused on teaching students scientific content knowledge and problem-solving skills. However, even the best content instruction does not guarantee improved learning, as studentsā€™ motivation ultimately determines whether or not they will take advantage of the content. The goal of our instruction is to address the ā€œleaky STEM pipelineā€ problem and retain more students in STEM fields. We designed a struggle-oriented instruction that tells stories about how even the greatest scientists struggled and failed prior to their discoveries. We describe how we have gone about designing this instruction to increase studentsā€™ motivation and better prepare them to interact and engage with content knowledge. We first discuss why we took this struggle-oriented approach to instruction by delineating the limitations of content-focused science instruction, especially from a motivational standpoint. Second, we detail how we designed and implemented this instruction in schools, outlining the factors that influenced our decisions under specific situational constraints. Finally, we discuss implications for future designers interested in utilizing this approach to instruction

    Establishing the feasibility of the dosimetric compliance criteria of RTOG 1308: phase III randomized trial comparing overall survival after photon versus proton radiochemotherapy for inoperable stage II-IIIB NSCLC.

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    BACKGROUND: To establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans. METHODS: Twenty-six lung IMRT and 26 proton PSPT plans were included in the study. Dose Volume Histograms (DVHs) for targets and normal structures were analyzed. The quality of IMRT plans was assessed using a knowledge-based engineering tool. RESULTS: Most of the RTOG 1308 dosimetric criteria were achieved. The deviation unacceptable rates were less than 10 % for most criteria; however, a deviation unacceptable rate of more than 20 % was computed for the planning target volume minimum dose compliance criterion. Dose parameters for the target volume were very close for the IMRT and PSPT plans. However, the PSPT plans led to lower dose values for normal structures. The dose parameters in which PSPT plans resulted in lower values than IMRT plans were: lung V5Gy (%) (34.4 in PSPT and 47.2 in IMRT); maximum spinal cord dose (31.7 Gy in PSPT and 43.5 Gy in IMRT); heart V5Gy (%) (19 in PSPT and 47 in IMRT); heart V30Gy (%) (11 in PSPT and 19 in IMRT); heart V45Gy (%) (7.8 in PSPT and 12.1 in IMRT); heart V50% (Gy) (7.1 in PSPT and 9.8 in IMRT) and mean heart dose (7.7 Gy in PSPT and 14.9 Gy in IMRT). CONCLUSIONS: The revised RTOG 1308 dosimetric compliance criteria are feasible and achievable

    Study of a 0.35 THz extended interaction oscillator driven by a pseudospark-sourced sheet electron beam

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    A compact high-power extended interaction oscillator (EIO) driven by a pseudospark-sourced (PS-sourced) sheet electron beam (SEB) is presented at 0.35 THz. It combines the advantages of a planar interaction circuit and a SEB generated from the PS discharge, including a large beam cross-section, high gain per unit length, and high current density with the additional benefit of not requiring an external focusing magnetic field. Staying within what is achievable with microfabrication techniques, the influence of tolerance on the Q value, resonance frequency, and characteristic impedance was investigated. The effect of surface roughness caused by the manufacturing method on Ohmic loss of the material surface was studied. The advanced microfabrication techniques of Ultra Violet Lithographie, Galvanik, and Abformung (UV-LIGA) and Nano-computer numerical control (Nano-CNC), which are capable of realizing high precision and a metal surface of sufficient smoothness, were proposed to manufacture the planar structures. The effect of plasma density in PS-sourced SEB on the resonance frequency of the EIO circuit was investigated. The simulation results showed that the output signal had a slight frequency upshift and a decrease of the output power as the plasma density increased at 0.35 THz, which is consistent with the theoretical analysis. Beam-wave interaction simulations for this planar EIO predicted a peak output power of 1.8 kW at 0.35 THz using an effective value of conductivity of 1.1 Ɨ 10 7 S/m to take into account the skin depth and surface roughness

    Heteroskedasticity of Unknown Form in Spatial Autoregressive Models with Moving Average Disturbance Term

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    In this study, I investigate the necessary condition for the consistency of the maximum likelihood estimator (MLE) of spatial models with a spatial moving average process in the disturbance term. I show that the MLE of spatial autoregressive and spatial moving average parameters is generally inconsistent when heteroskedasticity is not considered in the estimation. I also show that the MLE of parameters of exogenous variables is inconsistent and determine its asymptotic bias. I provide simulation results to evaluate the performance of the MLE. The simulation results indicate that the MLE imposes a substantial amount of bias on both autoregressive and moving average parameters

    Human antibodies targeting cell surface antigens overexpressed by the hormone refractory metastatic prostate cancer cells: ICAM-1 is a tumor antigen that mediates prostate cancer cell invasion

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    Transition from hormone-sensitive to hormone-refractory metastatic tumor types poses a major challenge for prostate cancer treatment. Tumor antigens that are differentially expressed during this transition are likely to play important roles in imparting prostate cancer cells with the ability to grow in a hormone-deprived environment and to metastasize to distal sites such as the bone and thus, are likely targets for therapeutic intervention. To identify those molecules and particularly cell surface antigens that accompany this transition, we studied the changes in cell surface antigenic profiles between a hormone-sensitive prostate cancer line LNCaP and its hormone-refractory derivative C4-2B, using an antibody library-based affinity proteomic approach. We selected a naĆÆve phage antibody display library to identify human single-chain antibodies that bind specifically to C4-2B but not LNCaP. Using mass spectrometry, we identified one of the antibody-targeted antigens as the ICAM-1/CD54/human rhinovirus receptor. Recombinant IgG1 derived from this single-chain antibody binds to a neutralizing epitope of ICAM-1 and blocks C4-2B cell invasion through extracellular matrix in vitro. ICAM-1 is thus differentially expressed during the transition of the hormone-sensitive prostate cancer cell line LNCaP to its hormone-refractory derivative C4-2B, plays an important role in imparting the C4-2B line with the ability to invade, and may therefore be a target for therapeutic intervention

    Time to full enteral feeding for very low-birth-weight infants varies markedly among hospitals worldwide but may not be associated with incidence of necrotizing enterocolitis:The NEOMUNE-NeoNutriNet Cohort Study

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    Background: Transition to enteral feeding is difficult for very low-birth-weight (VLBW; ā‰¤1500 g) infants, and optimal nutrition is important for clinical outcomes. Method: Data on feeding practices and short-term clinical outcomes (growth, necrotizing enterocolitis [NEC], mortality) in VLBW infants were collected from 13 neonatal intensive care units (NICUs) in 5 continents (n = 2947). Specifically, 5 NICUs in Guangdong province in China (GD), mainly using formula feeding and slow feeding advancement (n = 1366), were compared with the remaining NICUs (non-GD, n = 1581, Oceania, Europe, United States, Taiwan, Africa) using mainly human milk with faster advancement rates. Results: Across NICUs, large differences were observed for time to reach full enteral feeding (TFF; 8ā€“33 days), weight gain (5.0ā€“14.6 g/kg/day), āˆ†z-scores (āˆ’0.54 to āˆ’1.64), incidence of NEC (1%ā€“13%), and mortality (1%ā€“18%). Adjusted for gestational age, GD units had longer TFF (26 vs 11 days), lower weight gain (8.7 vs 10.9 g/kg/day), and more days on antibiotics (17 vs 11 days; all P <.001) than non-GD units, but NEC incidence and mortality were similar. Conclusion: Feeding practices for VLBW infants vary markedly around the world. Use of formula and long TFF in South China was associated with more use of antibiotics and slower weight gain, but apparently not with more NEC or higher mortality. Both infant- and hospital-related factors influence feeding practices for preterm infants. Multicenter, randomized controlled trials are required to identify the optimal feeding strategy during the first weeks of life
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