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41.
The Why2-Atlas tutoring system presents students with qualitative physics questions and encourages them to explain their answers through natural language. Although there are inexpensive techniques for analyzing explanations, we claim that better understanding is necessary for use within tutoring systems. In this paper we motivate and describe how the system creates and uses a deeper proof-based representation of student essays in order to provide students with substantive feedback on their explanations. We describe in detail the abductive reasoner, Tacitus-lite+, that we use within the tutoring system. We also discuss evaluation results for an early version of the Why2-Atlas system and a subsequent evaluation of the theorem-proving module. We conclude with the discussion of work in progress and additional future work for deriving more benefits from a proof-based approach for tutoring applications. 相似文献
42.
Abstract We show how many-body ground state entanglement information may be extracted from sub-system energy measurements at zero temperature. A precise relation between entanglement and energy fluctuations is demonstrated in the weak coupling limit. Examples are given with the two-state system and the harmonic oscillator, and energy probability distributions are calculated. Comparisons made with recent qubit experiments show this type of measurement provides another method to quantify entanglement with the environment. 相似文献
43.
Christina M. Rudin-Brown Michael G. LennéJessica Edquist Jordan Navarro 《Accident; analysis and prevention》2012
Although collisions at level crossings are relatively uncommon occurrences, the potential severity of their consequences make them a top priority among safety authorities. Twenty-five fully-licensed drivers aged between 20 and 50 years participated in a driving simulator study that compared the efficacy, and drivers’ subjective perception, of two active level crossing traffic control devices: flashing lights with boom barriers and standard traffic lights. Because of its common usage in most states in Australia, a stop sign-controlled level crossing served as the passive referent. Although crossing violations were less likely at the level crossings controlled by active devices than at those controlled by stop signs, both kinds of active control were associated with a similar number of violations. Further, the majority (72%) of drivers reported preferring flashing lights to traffic lights. Collectively, results indicate that the installation of traffic lights at real-world level crossings would not be likely to offer safety benefits over and above those provided already by flashing lights with boom barriers. Furthermore, the high rate of violations at passively controlled crossings strongly supports the continued practice of upgrading level crossings with active traffic control devices. 相似文献
44.
Jordan Schilbach 《国外电子测量技术》2014,(7)
正1引言移动数据流量的很大部分发生在室内。确保室内高密度用户的最佳网络质量显得特别重要。为了规划、实施和优化室内无线网络,首选必须对所有广泛使用的网络的无线信道质量进行可靠和全面评估。极其轻便和紧凑的路测扫描仪非常适合这一目标。甚至采用背包系统就能并行测量所有相关标准,因此极大缩短了测量时间。因为宽带市场上涌现出智能手机和平板电脑,移动宽带数据业务应用急速增加。仅2012年,全球移动数据 相似文献
45.
Eduardo Di Mauro Matteo Camaggi Nils Vandooren Caleb Bayard Jordan De Angelis Alessandro Pezzella Bill Baloukas Richard Silverwood Abdellah Ajji Christian Pellerin Clara Santato 《Polymer International》2019,68(5):984-991
In the human body, the black‐brown biopigment eumelanin blocks harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV‐absorption properties. We herein report an assessment of the biopigment eumelanin as a nature‐inspired additive for plastics to enhance their UV absorption. Since eumelanin is produced by natural sources and is nontoxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, the eumelanin‐containing films of commercial ethylene–vinyl acetate copolymer, a plastic used for packaging applications, were obtained by melt compounding and compression molding. The biopigment dispersion in the films was improved by means of the melanin free acid treatment. It was observed that eumelanin amounts as low as 0.8 wt% caused an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal stability and photostability of the films: the biopigment proved to be double‐edged, working both as UV‐absorption enhancer and photo‐prooxidant, as thermogravimetric analysis and infrared spectroscopy revealed. © 2019 Society of Chemical Industry 相似文献
46.
Tiana D. Warren Krishna Patel Jordan L. Rivera James R. Eshleman Marc Ostermeier 《American Institute of Chemical Engineers》2020,66(3):e16688
Improved prodrug-activating enzymes have the potential to increase the therapeutic efficacy of gene-directed enzyme prodrug therapy (GDEPT). Yeast cytosine deaminase (yCD) is commonly used to convert the prodrug 5-fluorocytosine (5-FC) to the chemotherapeutic 5-fluorouracil for GDEPT. Mutagenesis studies on yCD aimed at improving its application in GDEPT have been limited to subsets of residues or have sought to improve a single property of the enzyme. We performed comprehensive site-saturation mutagenesis (CSM) on yCD designed to create all 2,983 possible unique protein mutants with a single amino acid substitution. We identified active variants through Escherichia coli genetic complementation and screened these mutants, and combinations thereof, for increased ability to sensitize E. coli and HT1080 fibrosarcoma cells to 5-FC. Several mutants identified in this study showed increased sensitization ability for both E. coli and HT1080 cells indicating that CSM is an effective directed evolution tool for identifying unexpectedly beneficial mutations. 相似文献
47.
48.
Jordan P. Hooker Florian Feist Laura Delafresnaye Leonie Barner Christopher Barner‐Kowollik 《Advanced functional materials》2020,30(26)
A new strategy for particle synthesis is enabled by utilizing modern synthetic, polymer, and photochemical techniques to facilitate the synthesis of highly narrow–disperse multifunctional microspheres from visible‐light induced crosslinking of prepolymers in both a single and dual polymer system. The approach requires no stabilizers, bases, or initiators, and proceeds at ambient temperature to yield microspheres with a tunable size range (0.25–5 µm) in less than 4 h, depending largely on solvent composition, but also polymer concentration (2–10 mg mL?1), ratio, and irradiation intensity (3–20 W). Critically, the visible‐light induced dimerization reaction exploited herein enables simple functional particle syntheses via a single polymer system. Underpinned by an in‐depth kinetic analysis of the particle formation as well as a detailed small molecule study, the mechanism for particle formation is also elucidated. Importantly, inherent advantages of the system are exploited for surface functionalization of residual acrylate and hydroxyl groups (generating inherently fluorescent particles). 相似文献
49.
Chigozie K. Muoto Eric H. Jordan Maurice Gell Mark Aindow 《Journal of Thermal Spray Technology》2011,20(4):802-816
In solution precursor plasma spray chemical precursor solutions are injected into a standard plasma torch and the final material
is formed and deposited in a single step. This process has several attractive features, including the ability to rapidly explore
new compositions and to form amorphous and metastable phases from molecularly mixed precursors. Challenges include: (a) moderate
deposition rates due to the need to evaporate the precursor solvent, (b) dealing on a case by case basis with precursor characteristics
that influence the spray process (viscosity, endothermic and exothermic reactions, the sequence of physical states through
which the precursor passes before attaining the final state, etc.). Desirable precursor properties were identified by comparing
an effective precursor for yttria-stabilized zirconia with four less effective candidate precursors for MgO:Y2O3. The critical parameters identified were a lack of major endothermic events during precursor decomposition and highly dense
resultant particles. 相似文献
50.
Stephen Frith 《Architectural Theory Review》2013,18(1):122-141
Taking a lead from the work of Hannah Arendt and from M. Christine Boyer, this paper seeks to locate the discussion concerning the virtual city in a traditional discourse concerning citizenship. In De civitate Dei, the theme of citizenship is shown to mask a metaphor for order and justice informed by right desire. This order is seen to be couched in late empire dialectics, concerning tlie agonistic state of human identity and of cities, and the necessity for sacrifice in the foundation of city order. Justice is based not in a discussion of rights but of virtue. Augustine renders the virtual city as a symbol of pilgrimage and participation. 相似文献