8,615 research outputs found
sj-docx-1-pss-10.1177_0956797620939054 – Supplemental material for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention
No full textSupplemental material, sj-docx-1-pss-10.1177_0956797620939054 for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention by Gordon Pennycook, Jonathon McPhetres, Yunhao Zhang, Jackson G. Lu and David G. Rand in Psychological Science</p
sj-pdf-2-pss-10.1177_0956797620939054 – Supplemental material for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention
No full textSupplemental material, sj-pdf-2-pss-10.1177_0956797620939054 for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention by Gordon Pennycook, Jonathon McPhetres, Yunhao Zhang, Jackson G. Lu and David G. Rand in Psychological Science</p
sj-docx-3-pss-10.1177_0956797620939054 – Supplemental material for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention
No full textSupplemental material, sj-docx-3-pss-10.1177_0956797620939054 for Fighting COVID-19 Misinformation on Social Media: Experimental Evidence for a Scalable Accuracy-Nudge Intervention by Gordon Pennycook, Jonathon McPhetres, Yunhao Zhang, Jackson G. Lu and David G. Rand in Psychological Science</p
Synthesis of erythrocyte glutathione in healthy adults consuming the safe amount of dietary protein
No full textBackground: The finding that plasma glutathione turnover decreases as dietary protein intake decreases suggests that the safe amount of dietary protein, although sufficient for maintenance of nitrogen balance, may be insufficient for maintenance of cellular glutathione. Objective: Our objective was to determine the effect of the safe protein intake on the erythrocyte glutathione synthesis rate and its relation with urinary 5-L-oxoproline excretion. Design: Erythrocyte glutathione synthesis and urinary 5-L-oxoproline excretion were measured in young adults (6 men and 6 women) by using an infusion of [13C2]glycine on 3 occasions: initially during the subjects' habitual protein intake (1.13 g · kg–1 · d–1) and on days 3 and 10 of consumption of a diet providing the safe protein intake (0.75 g · kg–1 · d–1). Results: Compared with baseline values, the fractional synthesis rate of erythrocyte glutathione was significantly lower (P < 0.05) on days 3 and 10 of the diet with the safe protein intake. Urinary 5-L-oxoproline excretion increased significantly (P < 0.05) above baseline by the third day of the diet with the safe protein intake and remained elevated. Erythrocyte glutathione concentrations and absolute synthesis rates decreased by day 3 but recovered to baseline values by day 10. Erythrocyte concentrations of cysteine, methionine, and serine remained unchanged, whereas erythrocyte concentrations of glycine, glutamic acid, and glutamine increased significantly by day 10. Conclusion: During adaptation to the safe amount of dietary protein, there are changes in the concentration and kinetics of erythrocyte glutathione that suggest a reduced antioxidant capacity and possible increased susceptibility to oxidant stress
A First- and Second-Order Motion Energy Analysis of Peripheral Motion Illusions Leads to Further Evidence of “Feature Blur” in Peripheral Vision
No full textAnatomical and physiological differences between the central and peripheral visual systems are well documented. Recent findings have suggested that vision in the periphery is not just a scaled version of foveal vision, but rather is relatively poor at representing spatial and temporal phase and other visual features. Shapiro, Lu, Huang, Knight, and Ennis (2010) have recently examined a motion stimulus (the “curveball illusion”) in which the shift from foveal to peripheral viewing results in a dramatic spatial/temporal discontinuity. Here, we apply a similar analysis to a range of other spatial/temporal configurations that create perceptual conflict between foveal and peripheral vision.To elucidate how the differences between foveal and peripheral vision affect super-threshold vision, we created a series of complex visual displays that contain opposing sources of motion information. The displays (referred to as the peripheral escalator illusion, peripheral acceleration and deceleration illusions, rotating reversals illusion, and disappearing squares illusion) create dramatically different perceptions when viewed foveally versus peripherally. We compute the first-order and second-order directional motion energy available in the displays using a three-dimensional Fourier analysis in the (x, y, t) space. The peripheral escalator, acceleration and deceleration illusions and rotating reversals illusion all show a similar trend: in the fovea, the first-order motion energy and second-order motion energy can be perceptually separated from each other; in the periphery, the perception seems to correspond to a combination of the multiple sources of motion information. The disappearing squares illusion shows that the ability to assemble the features of Kanisza squares becomes slower in the periphery.The results lead us to hypothesize “feature blur” in the periphery (i.e., the peripheral visual system combines features that the foveal visual system can separate). Feature blur is of general importance because humans are frequently bringing the information in the periphery to the fovea and vice versa
On the Perturbation of LU, Cholesky, and QR Factorizations
No full textIn this paper error bounds are derived for a first order expansion of the LU factorization of a perturbation of the identity. The results are applied to obtain perturbation expansions of the LU, Cholesky, and QR factorizations. This report is available by anonymous ftp from thales.cs.umd.edu in the directory pub/reports. y Department of Computer Science and Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742. This work was supported in part by the Air Force Office of Scientific Research under Contract AFOSR-87-0188 and was done while the author was a visiting faculty member at the Institute for Mathematics and Its Applications, The University of Minnesota, Minneapolis, MN 55455. On the Perturbation of LU, Cholesky, and QR Factorizations G. W. Stewart ABSTRACT In this paper error bounds are derived for a first order expansion of the LU factorization of a perturbation of the identity. The results are applied to obtain perturbation expansions of..
Modelling of the <sup>177m</sup>Lu/<sup>177</sup>Lu radionuclide generator
No full textIn order to determine the potential of 177mLu/177Lu radionuclide generator in 177Lu production it is important to establish the technical needs that can lead to a clinically acceptable 177Lu product quality. In this work, a model that includes all the processes and the parameters affecting the performance of the 177mLu/177Lu radionuclide generator has been developed. The model has been based on the use of a ligand to complex 177mLu ions, followed by the separation of the freed 177Lu ions. The dissociation kinetics of the Lu-ligand complex has been found to be the most crucial aspect governing the specific activity and 177mLu content of the produced 177Lu. The dissociation rate constants lower than 1*10-11 s-1 would be required to lead to onsite 177Lu production with specific activity close to theoretical maximum of 4.1 TBq 177Lu/mg Lu and with 177mLu content of less than 0.01%. Lastly, the calculations suggest that more than one patient dose per week can be supplied for a period of up to 7 months on starting with the 177mLu produced using 3 g Lu2O3 target with 60% 176Lu enrichment. The requirements of the starting 177mLu activity production needs to be adapted depending on the required patient doses, and the technical specifications of the involved 177mLu-177Lu separation process.RST/Applied Radiation & IsotopesChemE/Catalysis Engineerin
Solid phase extraction-based separation of the nuclear isomers <sup>177m</sup>Lu and <sup>177</sup>Lu
No full textA solid phase extraction based 177mLu-177Lu separation method has been investigated for its feasibility to be used in the radionuclide generator. The use of 2,2′,2”-(10-(2,6-dioxotetrahydro-2H-pyran-3-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid, (DOTAGA-anhydride) allowed grafting of DOTA (1,4,7,10-tetraazacyclododecane N,N′,N″,N‴-tetraacetic acid) complex on the surface of commercially available amino propyl silica. The grafting of DOTA has been confirmed by several characterization techniques. The thermogravimetric analysis reveals that the 0.33 mmol DOTA groups have been grafted per gram of silica. However, during the Lu ion complexation, a 10 times lower Lu adsorption capacity of 0.03 mmol g−1 could be achieved under the studied reaction conditions. The results indicate that the grafting of DOTA on solid affects the Lu coordination and also influences the kinetics of Lu-DOTA complexation. The weak coordination resulted in high 177mLu leakage, while the unreacted DOTA groups interfer with the 177Lu release. This is evident from the 0.3% 177mLu leakage combined with a177Lu extraction efficiency of 25%. Overall, the results show a177mLu-177Lu separation with a maximum 177Lu/177mLu activity ratio of 25. But this is still far away from clinically acceptable activity ratio of 10,000 for which future work is recommended.RST/Applied Radiation & Isotope
Investigation on the Lu-Kumar queueing network
No full textMulti-class re-entrant networks are common in semiconductor, communication and other complex manufacturing systems. The project seeks to investigate the Lu-Kumar re-entrant queueing network through simulation. The Lu-Kumar network is a simple re-entrant system used as a starting point in examining multi-class queueing networks. Insights gained through simulation can have potential application in improving manufacturing systems.
It is common to find literature that discusses the stability of such systems using fluid models. This project takes on a different approach by examining the stability of such systems using a deterministic model through simulation.
The experimental results show that the stability conditions of the Lu-Kumar network in a deterministic model is different from those proved using fluid models. The stability conditions established using fluid models do not apply in a deterministic case. The deterministic model have discrete regions of stability, the author conjectures that it is most likely achieved through synchronization.
Further exploration on the intrinsic properties of the model is conducted through simulation using Poisson arrivals and exponential service times. It is found that the network has a linear relationship with M/M/1 queue times, with the virtual station showing the strongest linearity. The results support the author’s belief that the Lu-Kumar re-entrant network can be approximated to a G/G/k queue model if the coefficient of variation can be determined.
In addition, recommendations are provided for future work to further develop the understanding of multi-class re-entrant queueing networks.Bachelor of Engineering (Mechanical Engineering
G-jitter effects on half floating-zone convection in intermediate-frequency range
No full textThe g-jitter influence on thermocapillary convection and critical Marangoni number in a liquid bridge of half-floating rone was discussed in the low frequency range of 0.4 to 1.5 Hz in a previous paper. This paper extended the experiments to the intermediate frequency range of 2 to 18 Hz, which htrs often been recorded as vibration environment of spacecrafts. The experiment was completed on the deck of a vibration machine, which gave a periodical applied acceleration to simulate the effects of g-jitter. The experimental results in the intermediate frequency range are different from that in the low frequency range. The velocity field and the shape of the free surface have periodical fluctuations in response to g-jitter. The amplitude of the periodical varying part of the temperature response decreases obviously with increasing frequency of g-jitter and vanishes almost when the frequency of g-jitter is high enough. The critical Marangoni number is defined to describe the transition from a periodical convection in response to g-jitter to an oscillatory convection due to internal instability, and will increase with increasing g-jitter frequency. According to the spectral analysis, it can be found that the oscillatory part of temperature is a superposition of two harmonic waves if the Marangoni number is larger than a critical value
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