2,343 research outputs found

    Parity anomaly of bound states and optical properties in semiconductor superlattices with structural defects

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    We investigate the property of the bound states with an infinite number of classical turning points in the semiconductor superlattices (SLā€™s) with the double-barrier and double-well structural defects. The anomalous parity sequence of these bound states violating the conventional parity rule is predicted. A physical mechanism on the origin of the bound states in the structural defect SLā€™s, different from the mechanism addressed in the previous literature, is proposed. Based upon it, the parity anomaly can be interpreted very well. In addition, we also study the property of the optical transition in this system, for instance, the evaluation of the optical transition probability from the bound states to the bound states, from the bound states to the delocalized scattering states, and from the scattering states to other scattering states, in detail.published_or_final_versio

    Rigorous electromagnetic analysis of a microcylindrical axilens with long focal depth and high transverse resolution

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    We first present nonparaxial designs for a microcylindrical axilens with different long focal depths and rigorously analyze electromagnetic field distributions of the axilens using integral equations and the boundary-element method. Numerical results show that the designed axilenses indeed have the special feature of attaining a long focal depth while keeping high transverse resolution for numerical apertures of 2.4, 2.0, and 1.0. The ratio between the extended focal depth of the designed axilens and the focal depth of the conventional focal lens is 1.41, the corresponding maximal extended focal depth of the axilens can reach 28 Ī¼m, and the spot size of the focal beam is āˆ¼10 Ī¼m over the focal range. Ā© 2001 Optical Society of America.published_or_final_versio

    Enhanced Coagulation of Titanium Tetrachloride Aided by the Modified Compound Bioflocculant

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    Ā© 2015 American Society of Civil Engineers. The compound bioflocculant (CBF) was modified by graft copolymerization of acrylic amide and dimethyl diallyl ammonium chloride, and the novel copolymer was denoted as MCBF. The effect of MCBF used as coagulant aid with titanium tetrachloride (TiCl4) was investigated for both high and low molecule weight natural organic matter (NOM) removal. Floc characteristics were studied using a laser diffraction particle-sizing device. Results indicated that the monomers were successfully grafted onto the CBF, and the molecule weight and zeta potential of CBF were greatly improved. The MCBF with TiCl4 exhibited synergistic effect by promoting NOM removal, especially at low TiCl4 doses. Additionally, using MCBF as a coagulant aid with TiCl4 can significantly increase the floc growth rate, size, strength, and broken-floc recoverability. The effect of MCBF on fractal dimension of flocs generated by TiCl4 depended on NOM properties. Both coagulation performance and floc properties were significantly affected by dosing sequence

    Peixin Yang's Economic thought and its Outcomes in the 1980s, Early in China's Reform, and China's Reform Miracle

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    During the initial period of reform, China's prudent handling of the moneyā€”price relationship while simultaneously bringing inflation and unemployment under control had a far-reaching influence on economic theory as well as practical significance. The country's successful experience constituted a miracle beyond the dreams of authoritative international financial authorities and experts. The famous American Nobel Prize winner, the economist Milton Friedman, once said that anyone who could explain China's success could win the Nobel Prize. In today's complex world, with its recurrent financial turmoil and intensified threat of war, China's successful experience in the early phases of reform has important significance for developing socialism with Chinese characteristics and maintaining the country's economic and financial security and the interests of the great mass of the people. We should sum up this experience to strengthen confidence in our institutions, our path, and our theory

    The disposition and pharmacokinetics of Dioscorea nipponica Makino extract in rats

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    This study was aimed to investigate the disposition and pharmacokinetics of the total saponins of dioscorea (TSD) in rats. Male Sprague-Dawley rats were orally administrated with 3H labeled TSD at a single dose ratio of 80 mg TSD per 1 kg rat. Blood samples and feces were collected at different time points to measure the level of TSD activity. At the final time point, determination of the disposition of TSD in lung, kidney, heart, liver, adrenal, and small intestine were performed. From the blood samples' emission of radioactivity, pharmacokinetic parameters were derived as T1/2 = 33.33 Ā± 4.48 h, T max = 6.5 Ā± 0.71 h, AUC = 119400 Ā± 421097.67, and C max = 2643.33 Ā± 192.26 dpm/ml. There was 51.609% of 3H labeled substance excreted in 24 h. These results suggested that blood concentration of 3H-TSD was extremely low and the majority of TSD was excreted in the feces. The TSD was extensively distributed to multitissues. The radioactivity level was measured to be the highest in the liver, adrenal gland, and wall of the gastrointestinal tract. The radioactivity of TSD was still being detected in blood after 96 h. This showed TSD was excreted in vivo very slowly. Ā© 2008 Academic Journals.published_or_final_versio

    Public cloud data auditing with practical key update and zero knowledge privacy

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    Data integrity is extremely important for cloud based storage services, where cloud users no longer have physical possession of their outsourced files. A number of data auditing mechanisms have been proposed to solve this problem. However, how to update a cloud user\u27s private auditing key (as well as the authenticators those keys are associated with) without the user\u27s re-possession of the data remains an open problem. In this paper, we propose a key-updating and authenticator-evolving mechanism with zero-knowledge privacy of the stored files for secure cloud data auditing, which incorporates zero knowledge proof systems, proxy re-signatures and homomorphic linear authenticators. We instantiate our proposal with the state-of-the-art Shacham-Waters auditing scheme. When the cloud user needs to update his key, instead of downloading the entire file and re-generating all the authenticators, the user can just download and update the authenticators. This approach dramatically reduces the communication and computation cost while maintaining the desirable security. We formalize the security model of zero knowledge data privacy for auditing schemes in the key-updating context and prove the soundness and zero-knowledge privacy of the proposed construction. Finally, we analyze the complexity of communication, computation and storage costs of the improved protocol which demonstrates the practicality of the proposal

    Privacy in crowdsourcing:a systematic review

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    The advent of crowdsourcing has brought with it multiple privacy challenges. For example, essential monitoring activities, while necessary and unavoidable, also potentially compromise contributor privacy. We conducted an extensive literature review of the research related to the privacy aspects of crowdsourcing. Our investigation revealed interesting gender differences and also differences in terms of individual perceptions. We conclude by suggesting a number of future research directions.</p

    Confucian Principles: A Study of Chinese Americansā€™ Interpersonal Relationships in Selected Childrenā€™s Picturebooks

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    [[abstract]]There has not been enough critical analysis of childrenā€™s literature by and about Chinese Americans, especially when compared to other minority groups in the United States. In particular, Chinese American historical books lack extensive analysis. It is important to reflect cultural accuracy in literature and to help children develop clear concepts of self and others by providing precise cultural and physical characteristics of people. While cultural authenticity allows children the opportunity to see a reflection of real experiences within a book instead of seeing stereotypes or misrepresentations, obtaining correct information about a certain time period can help children to see images of immigration accurately represented in literature. Using the Confucian delineation of interpersonal relationships as the major criterion of cultural authenticity, this article examines three currently available childrenā€™s picturebooks set in the historical period between 1848 and 1885. In addition to exploring how Chinese Americansā€™ interpersonal relationships are portrayed in these childrenā€™s historical books, this article argues for more proactive inclusion of the diversity in selection of picturebooks.[[notice]]č£œę­£å®Œ

    Would school closure for the 2009 H1N1 influenza epidemic have been worth the cost?: a computational simulation of Pennsylvania

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    <p>Abstract</p> <p>Background</p> <p>During the 2009 H1N1 influenza epidemic, policy makers debated over whether, when, and how long to close schools. While closing schools could have reduced influenza transmission thereby preventing cases, deaths, and health care costs, it may also have incurred substantial costs from increased childcare needs and lost productivity by teachers and other school employees.</p> <p>Methods</p> <p>A combination of agent-based and Monte Carlo economic simulation modeling was used to determine the cost-benefit of closing schools (vs. not closing schools) for different durations (range: 1 to 8 weeks) and symptomatic case incidence triggers (range: 1 to 30) for the state of Pennsylvania during the 2009 H1N1 epidemic. Different scenarios varied the basic reproductive rate (R<sub>0</sub>) from 1.2, 1.6, to 2.0 and used case-hospitalization and case-fatality rates from the 2009 epidemic. Additional analyses determined the cost per influenza case averted of implementing school closure.</p> <p>Results</p> <p>For all scenarios explored, closing schools resulted in substantially higher net costs than not closing schools. For R<sub>0 </sub>= 1.2, 1.6, and 2.0 epidemics, closing schools for 8 weeks would have resulted in median net costs of 21.0billion(9521.0 billion (95% Range: 8.0 - 45.3billion).Themediancostperinfluenzacaseavertedwouldhavebeen45.3 billion). The median cost per influenza case averted would have been 14,185 (5,423āˆ’5,423 - 30,565) for R<sub>0 </sub>= 1.2, 25,253(25,253 (9,501 - 53,461)forR<sub>0</sub>=1.6,and53,461) for R<sub>0 </sub>= 1.6, and 23,483 (8,870āˆ’8,870 - 50,926) for R<sub>0 </sub>= 2.0.</p> <p>Conclusions</p> <p>Our study suggests that closing schools during the 2009 H1N1 epidemic could have resulted in substantial costs to society as the potential costs of lost productivity and childcare could have far outweighed the cost savings in preventing influenza cases.</p
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