Academic literature on the topic 'Forbidden Blocks'
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Journal articles on the topic "Forbidden Blocks"
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Walker, P. M. "Isomer building blocks andK-forbidden decays." Physica Scripta 92, no. 5 (April 12, 2017): 054001. http://dx.doi.org/10.1088/1402-4896/aa694d.
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Haglund, J., J. Morse, and M. Zabrocki. "A Compositional Shuffle Conjecture Specifying Touch Points of the Dyck Path." Canadian Journal of Mathematics 64, no. 4 (August 1, 2012): 822–44. http://dx.doi.org/10.4153/cjm-2011-078-4.
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Abstract We introduce a q, t-enumeration of Dyck paths that are forced to touch the main diagonal at specific points and forbidden to touch elsewhere and conjecture that it describes the action of the Macdonald theory ∇ operator applied to a Hall–Littlewood polynomial. Our conjecture refines several earlier conjectures concerning the space of diagonal harmonics including the “shuffle conjecture” (Duke J. Math. 126 (2005), pp. 195 − 232) for ∇ en[X]. We bring to light that certain generalized Hall–Littlewood polynomials indexed by compositions are the building blocks for the algebraic combinatorial theory of q, t-Catalan sequences, and we prove a number of identities involving these functions.
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Samoshkin, Vladlen, Victor Meleshko, and Artem Yakovenko. "DOPING IN SPORTS AND WAYS COMBATING VIOLATIONS ANTI-DOPING LEGISLATION." Sports Bulletin of the Dnieper 1 (2020): 142–54. http://dx.doi.org/10.32540/2071-1476-2019-1-142.
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Introduction and purpose of the study. In article to perform that doping is one of the serious of problem of modern sport. Defines important questions regarding antidoping rules and anti-doping control in sport. Given the promising solutions to the problems of doping in Ukraine. It is an extremely complex because it involves the interrelated medical, legal, political, moral, organizational, social and pedagogical aspects. To use the doping is the same to spread and the most to chase’s infringement of the law in branch of sport which to lie in the area of several fields by law. Just for this offence to foresee the several kinds of responsibility at the same time-administrative, civic. discipline’s and is particular event the criminal. The hypothesis of the study lies in the fact that in modern Olympics sport to observe the tendency of introduction in quality of doping by new improved substances and methods, gene and cellular doping and other achievement by medicine and biology. And according constantly to widen a list of drugs and methods WADA-AMA which inclusive three measures of inhibition: complete forbidden, forbidden only on the match and the drugs what limited at kinds of sport. Experts of Olympics sport by Ukraine would be constancy monitoring that tendencies and to improve of legislative and normative-legal base and infrastructure of the anti-doping policy which should be brought in line with modern international standards. The aim of the research is to determine the parents’ attitude to systematize the modern knowledge about the ways of effective counteraction to infringe by anti-doping legislation. Methods. Analysis, synthesis and systematization of scientific literature data and materials from the Internet. Results. The analysis of literary sources has found the next. To suppose that the partial modification’ athletes on the gene and cellular level will be appearance earlier than will be official to approve of cellular technologies treatment by ills. The world anti-doping code to action joint with International standards as documents what to concern by of all constituent part doping checkup that nostrified in Ukraine. By effort of WADA-AMA to exploit a new analytic methods to research of human growth hormone and biomarkers of gene doping and steroid profile of athletes. A list complete forbidden by WADA-AMA of drugs and methods include: anabolic mediators, hormones and modulators of metabolism, diuretics and camouflage agents, beta-2 agonists, peptide hormones and factors of growth, to manipulate with blood and urine, genetics doping (sexual modifications). The drugs that forbidden only on the match: stimulates, narcotics, cannabinoids, steroid hormones glucocorticoids. The drugs what limited at kinds of sport: beta-blocks. Method of doping checkup as analysis by proofs of biological passport athlete what to put together with steroid, hematological and endocrinology modules, don’t substitution traditional doping checkup by method search of forbidden substances in specimens but to add its. The underline what adversary of doping to insist on therefore that ergolitic substances and methods to kill the just idea of “fair play” - the moral code of world sport. According to code on the start all athletes must to have equal chances on the victory. Conclusions. Defines such class from forbidden WADA-AMA from a list of drugs and methods what is: complete forbidden; forbidden only on the match; limited the kinds of sport and frequency offence there for internal use. Defines that analysis by proofs of biological passport athlete to add the traditional doping checkup. To accentuate on the fact that doping pursuit to threaten for social functions of sport. Key words: doping, athlete, sport, anti-doping measures
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Rezig, Sadok, Nidhal Rezg, and Zied Hajej. "Online Activation and Deactivation of a Petri Net Supervisor." Symmetry 13, no. 11 (November 20, 2021): 2218. http://dx.doi.org/10.3390/sym13112218.
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This paper highlights algebraic and mathematical properties in symmetry with Petri nets in order to control automated systems such as flexible workshops, which represent one of the most important examples in industry and for discrete event systems in general. This project deals with the problem of forbidden state transition by using a new application of the theory of regions for supervisory control. In the literature, most control synthesis methods suffer greatly from a cumbersome calculation burden of the Petri net supervisor given the complex exploration of the state graph. Our new methodology lightens the computational load of the Petri net supervisor by choosing specific regions on the reachability graph, on which the control is calculated offline using CPLEX. The determined controller is activated online if the process enters the chosen region, and deactivated otherwise. All our experiments were applied in a flexible workshop implemented in our research laboratory, which was used to engrave selected models on glass blocks of different colors.
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Li, Xu Jia. "Homology, Hierarchy, and Space - A Case Study of Wu’s House." Advanced Materials Research 243-249 (May 2011): 1694–700. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1694.
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This paper is a case study of Wu’s house, which is located at the Majiamiao hutong, only several blocks away from the imperial palace—the Forbidden City in Beijing. It is a typical quadrangle called Siheyuan, or "four-side enclosed courtyard". Historians declared that, judging by the architectural style and interior decoration, the house might have been constructed in the late Ming dynasty [1], which means the history of the house could go back for more than 400 years. The complete story of the house and its owners can be divided into three parts: first, a house for a large feudal family before 1949; secondly, a house for a famous dramatist until 1966; and finally, a house for the city poor from the Great Cultural Revolution on. During 400 years of social evolution and revolution, especially in the past 50 years, the house and the families who lived in it underwent great changes. The precise homology and strict hierarchy in Siheyuan, implied by the order of orientation and scale of the buildings within the house, was weakened gradually by the “revolutionists” who tried to establish an absolute equality among the people in every detail of their lives, including their house. However, never will a house like Siheyuan be equal to every member in it because it was born of politics.
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Benedetto, Alessandro, Elena Biasibetti, Chiara Beltramo, Valentina Audino, Simone Peletto, Elena Maria Bozzetta, and Marzia Pezzolato. "Regucalcin expression profiles in veal calf testis: validation of histological and molecular tests to detect sex steroids illicit administration." PeerJ 9 (February 19, 2021): e10894. http://dx.doi.org/10.7717/peerj.10894.
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Background Sex steroids administration in meat producing animals is forbidden within the EU to preserve consumers’ safety, but continuous monitoring to identify resurgence of their misuse is needed. Among biomarkers related to sex steroids abuse in veal calves the regucalcin (RGN) mRNA perturbations in testis have been described in RNAlater samples. To setup novel diagnostic method, to update current tests available in National Residue Control Plans (NRCPs) and in legal dispute when illicit practices on farm animals are suspected, the reliability of RGN profiling was assessed by histological and molecular techniques. Methods Formalin fixed paraffin embedded (FFPE) testis samples, chosen being the most effective preservation strategy adopted by histological NRCPs and allowing easier retrospective analysis if required by legal disputes, were analyzed from veal calves treated with nandrolone, 17β-estradiol and a cocktail of the two hormones. RGN levels were determined by quantitative Real Time PCR and Immunohistochemistry assays. Test performances were assessed and compared by multiple ROC curves. Results Both tests resulted sensitive and specific, allowing to enrich, in future field investigation, novel integrated diagnostic protocols needed to unveil sex steroid abuse. Discussion Developed RT-qPCR and IHC methods confirmed RGN as a useful and robust biomarker to detect illegal administration of sex steroid hormones in veal calves. The developed methods, successfully applied to ten years old FFPE blocks, could allow both retrospective analysis, when supplementary investigations are requested by authorities, and future implementation of current NRCPs.
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Pappalardo, Giovanna, Simone Mineo, Serafina Carbone, Carmelo Monaco, Domenico Catalano, and Giovanni Signorello. "Preliminary Recognition of Geohazards at the Natural Reserve “Lachea Islet and Cyclop Rocks” (Southern Italy)." Sustainability 13, no. 3 (January 21, 2021): 1082. http://dx.doi.org/10.3390/su13031082.
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In this study, we present a preliminary recognition of geohazards at the natural reserve archipelago “Lachea Islet and Cyclop Rocks” by integrating infrared thermography (IRT) and morphological-aerial interpretation. The study area, located in the wider setting of the UNESCO (United Nations Educational, Scientific and Cultural Organization) World Heritage Mount Etna (eastern Sicily), is a worldwide renowned tourist destination suffering from a limited fruition due to the instability of rock masses. The peculiar setting of the area, represented by steep sea rocks and an islet, requires the employment of remote surveying methodologies for the preliminary slope characterization in the perspective of safe ground surveys. In this paper, IRT analysis allowed the recognition of signs of past rockfalls, as well as the presence of loose rock material likely laying in unstable conditions, thanks to the variation of the surface temperature characterizing the slope. The combination of IRT outcomes with morphological-aerial data allowed recognizing the potential source areas of future rockfalls, which were modeled through trajectory simulations. Results showed that a relevant strip of sea surrounding the studied sea rock could be crossed by falling blocks, suggesting the need of instituting a forbidden area for a safe fruition of the reserve. Furthermore, IRT allowed for the recognition of some peculiar features linked to the presence of tectonic lines. Such correspondence was validated by a comparison with literature structural data, proving the potential of such remote methodological approach. This represents a new aspect of the application of IRT to other fields of geosciences, thus representing a starting point for the scientific development of new technological branches.
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Fitzgerald, Des. "A Forest, a Maze, a Garden, a City." Cultural Politics 18, no. 3 (November 1, 2022): 388–406. http://dx.doi.org/10.1215/17432197-9964843.
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Abstract This article argues for a mutation in how mental health is conceived in the early twenty-first century. In this mutation, physical environments, in the form of homes, workplaces, and streetscapes, are understood as central to the production and maintenance of good mental health. Much writing on this topic has taken place within a rhetorical division between stereotypically urban buildings or spaces (tower blocks, for example), which are said to be harmful to the human mind, and idealized rural or green spaces, such as parks or small hamlets, understood to be psychologically restorative. This discourse, which has its roots in both cultural and scientific developments, has rendered mental disorder as, at least in part, a spatial problem—which is to say, as a problem that might be both understood through but also treated by spatial practices. The goal of the article is to establish the ground of this claim and to make some of its epistemic roots visible. The article begins with an ethnographic account of a contemporary intellectual movement aimed at populating urban spaces with trees in the name of global mental health. Then the discussion turns to a series of critical developments in the psychological and neurobiological sciences—the article demonstrates how these, in turn, are efflorescing into new links between the architectural and psychological sciences. The article shows how this scientific discussion is paralleled by developments in urban planning—Ebenezer Howard's program of the early twentieth century, set out in Garden Cities of To-Morrow, is taken as exemplary here. The article ends with a reading of Clive Barker's 1985 short story “The Forbidden” and of the film Candyman, which it gave rise to, whose shared sense of horror at the visceral consequences of failed urban experiments, I argue, should be read as a critical inflection point for the contemporary relationship between psychology and architecture.
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Lei, Wanpeng, Liming Xiong, Junfeng Du, and Jun Yin. "Forbidden Pairs of Disconnected Graphs for Traceability of Block-Chains." Symmetry 14, no. 6 (June 13, 2022): 1221. http://dx.doi.org/10.3390/sym14061221.
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Each traceable graph must be a block-chain; however, a block-chain is not necessarily traceable in general. Whether a given graph is a block-chain or not can be easily verified by a polynomial algorithm. It occurs to us that forbidden subgraph conditions for a block-chain are traceable. In this article, we characterize all pairs of disconnected forbidden subgraphs for the traceability of block-chains, so as to completely solve pairs of forbidden subgraphs for the traceability of block-chains (including disconnected and connected).
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Kulli, V. R., and K. M. Niranjan. "The Semi-splitting Block Graph of a Graph." Journal of Scientific Research 2, no. 3 (August 23, 2010): 485. http://dx.doi.org/10.3329/jsr.v2i3.3626.
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We present here characterizations of graphs whose semi-splitting block graphs are planar, outer planar. Also we characterize graphs whose semi-splitting block graphs are planar and outer planar in terms of forbidden sub graphs. Keywords: Semi-splitting; Block; Planar; Outer planar; Forbidden. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i3.3626 J. Sci. Res. 2 (3), 485-488 (2010)
Dissertations / Theses on the topic "Forbidden Blocks"
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Vishwakarma, Prateek Kumar. "Positivity preservers forbidden to operate on diagonal blocks." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5537.
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The question of which functions acting entrywise preserve positive semidefiniteness has
a long history, beginning with the Schur product theorem [Crelle 1911], which implies
that absolutely monotonic functions (i.e., power series with nonnegative coefficients)
preserve positivity on matrices of all dimensions. A famous result of Schoenberg and
of Rudin [Duke Math. J. 1942, 1959] shows the converse: there are no other such
functions.
Motivated by modern applications, Guillot and Rajaratnam [Trans. Amer. Math.
Soc. 2015] classified the entrywise positivity preservers in all dimensions, which act
only on the off-diagonal entries. These two results are at “opposite ends”, and in both
cases the preservers have to be absolutely monotonic.
The goal of this thesis is to complete the classification of positivity preservers that
act entrywise except on specified “diagonal/principal blocks”, in every case other than
the two above. (In fact we achieve this in a more general framework.) The ensuing
analysis yields the first examples of dimension-free entrywise positivity preservers -
with certain forbidden principal blocks - that are not absolutely monotonic.
Book chapters on the topic "Forbidden Blocks"
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Diner, Öznur Yaşar, Daniël Paulusma, Christophe Picouleau, and Bernard Ries. "Contraction Blockers for Graphs with Forbidden Induced Paths." In Lecture Notes in Computer Science, 194–207. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18173-8_14.
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Esen, Ersin, and A. Aydın Alatan. "Block Based Video Data Hiding Using Repeat Accumulate Codes and Forbidden Zone Data Hiding." In Advances in Multimedia Information Processing - PCM 2009, 731–42. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-10467-1_64.
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"Functions Acting Outside Forbidden Diagonal Blocks." In Matrix Analysis and Entrywise Positivity Preservers, 168–75. Cambridge University Press, 2022. http://dx.doi.org/10.1017/9781108867122.024.
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Thomson, Peter. "Angels and Ghosts in Irkutsk." In Sacred Sea. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195170511.003.0023.
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For thousands of the tsars’ political enemies in imperial Russia, the bad news was that they were being stripped of their wealth, their civil rights, and their aristocratic privileges and exiled to Siberia, perhaps never to return home. The good news was that they were being sent to Irkutsk. In the continent-sized freezer and prison camp that was Siberia, Irkutsk was a place where formerly dignified and refined Russians not only might survive but might even be able to live with something approaching the dignity and refinement of their lives back in St. Petersburg or Moscow. “The best of all Siberian towns is Irkutsk,” Chekhov wrote on his way east to report on the prison camps of Sakhalin Island in the Pacific in 1890. The city is more than 5,000 kilometers from Moscow, 250 kilometers from Mongolia, and twice as close to Beijing’s Forbidden City as to the Kremlin, and even after the first road was cut from Moscow in the 1860s, it took a month of miserable travel to get here under the best conditions. It’s also a place where it was said that you could hear a symphony or an opera as good as any in St. Petersburg, or attend the theater in a hall that would grace the most elegant streets of the Russian capital. Where, today, you can walk down tree-lined sidewalks fronting elegant commercial blocks with well-stocked shops and cafes serving the best coffee west of San Francisco. Where green and gold spires descend to ornate white Orthodox churches and poplar-shaded log houses with gracefully carved eaves and window frames extend for what seem like miles in every direction. Irkutsk was founded in the mid-seventeenth century as a Cossack ostrog, a fort at the confluence of the Irkut and Angara rivers, and by the mid-eighteenth century it had become the administrative center of Eastern Siberia as the Russian Empire pushed its frontier ever eastward. It had also become the economic hub of the region, “the warehouse of Russia,” as the contemporary writer Mark Sergeyev puts it, where, he says, quoting a Russian proverb, “everything was on sale except pigeon’s milk.”
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Joyce, Rosemary A. "Interlude 1." In The Future of Nuclear Waste, 50–58. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190888138.003.0003.
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Stone from the outer rim of an enormous square is dynamited and then cast into large concrete/stone blocks, dyed black, and each about 25 feet on a side. They are deliberately irregular and distorted cubes. The cubic blocks are set in a grid, defining a square, with 5-foot-wide “streets” running both ways. You can get “in” it, but the streets lead nowhere, and they are too narrow to live in, farm in, or even meet in. It is a massive effort to deny use. At certain seasons it is very, very hot inside because of the black masonry’s absorption of the desert’s high sun-heat load. It is an ordered place, but crude in form, forbidding, and uncomfortable....
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Joyce, Rosemary A. "Interlude 3." In The Future of Nuclear Waste, 122–35. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190888138.003.0007.
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THE GOAL THAT THE markers experts imagined for the nuclear waste repository marker was for it to be imposing, impressive, yet unattractive. They wanted to produce a physical installation that could convey these meanings through its form. In Team A’s designs, this involved using “menacing” features like sharp pointed elements, made of materials like stone or metal, disrupting any kind of orderly layout. Where Forbidding Blocks worked as an installation of a kind of “city” that would be physically uncomfortable to live in, and Menacing Earthworks would crowd and overwhelm the visitor, a third design concept, Spikes Bursting through Grid, was more directly threatening (...
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Faxneld, Per. "Helena Petrovna Blavatsky (The Theosophical Society), The Secret Doctrine (1888)." In Satanism: A Reader, 71—C5N58. Oxford University PressNew York, 2023. http://dx.doi.org/10.1093/oso/9780199913534.003.0005.
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Abstract This chapter focuses on Helena Petrovna Blavatsky’s The Secret Doctrine (1888). Blavatsky, the chief ideologist of the Theosophical Society, was the first person to present a positive understanding of Satan in an exclusively esoteric or religious (as opposed to literary or political) context. She argues that Satan—or Lucifer, or the Devil, as she often uses the names interchangeably—brought humankind spiritual wisdom by offering us the forbidden fruit from the Tree of Knowledge in the Garden of Eden. He is therefore “the spirit of Intellectual Enlightenment and Freedom of Thought,” and the so-called Fall of Man was in fact a positive event, an initiation into esoteric knowledge. An important building block in Blavatsky’s construction of Satan was contemporary (semi-) scholarly understandings of ancient Gnosticism.
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Cronin, James E. "Toward a Cold War World Order." In Fragile Victory, 76–103. Yale University Press, 2023. http://dx.doi.org/10.12987/yale/9780300247855.003.0004.
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This chapter confirms whether the emerging Cold War order was truly liberal or conducive to liberalism. In the vast territories controlled by Communist states, liberalism and democracy were not so much alien as forbidden by the ruling parties. It notes the difficulties in characterizing the political order as liberal in large sections of the world that remained part of European empires. The chapter explains how the world was divided behind an illiberal bloc and a Western approach, which was in theory committed to liberalism in politics and to an economy that was capitalist. It highlights that the liberal order that existed in the non-Communist world was still an aspiration, and its future would be worked out within the framework of the Cold War.
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Cervin, Georgia. "From Amateurism to Professionalism." In Degrees of Difficulty, 35–56. University of Illinois Press, 2021. http://dx.doi.org/10.5622/illinois/9780252043772.003.0003.
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Chapter 2 argues that Olympic economic policy was a place of challenge in Cold War gymnastics, rather than cooperation, with opposing views extending from fans and media to differences between the Federation internationale de gymnastique (FIG) and the International Olympic Committee (IOC). Amateurism was a major issue for the IOC under Avery Brundage’s presidency, forbidding athletes any financial benefit from sport. State support rendered the amateur status of Eastern bloc gymnasts questionable. For US gymnasts, the amateur rule contributed to the decreased age of their best women, despite opportunities in collegiate gymnastics. Changed economic prospects coincided with the rise of US gymnastics. By the 1970s, the Olympics were commercializing, with Adidas branding appearing on leotards. By the 1980s, the games were professionalizing, as athletes advertised products and launched entertainment careers. But the FIG remained opposed to professionalization, leading to financial trouble in the 1990s and increasing its dependence on the IOC.
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Keats, Jonathon. "Great Firewall." In Virtual Words. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195398540.003.0018.
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The Chinese government declared 1996 the Year of the Internet. There wasn’t much to it: only one person in ten thousand was connected—at a modem speed of 14.4 kilobits per second—and 86 percent of the population had never encountered a computer. Even in universities email was still a novelty, haltingly introduced in 1994. Yet in one respect China was the most advanced nation on the planet. Using equipment supplied by Sun Microsystems and Cisco, the Chinese Public Security Bureau had corralled the entire country, all 3,705,000 square miles, within a fanghuo qiang, or firewall. The firewall promised to make the internet safe for autocracy. All online communication could be monitored, at least in principle, and access to any website could be denied. On February 1, 1996, Premier Li Peng signed State Council Order 195, officially placing the government “in charge of overall planning, national standardization, graded control, and the development of all areas related to the internet,” and expressly forbidding users “to endanger national security or betray state secrets.” Enforcement was arbitrary. Discipline was imposed by the dread of uncertainty. This was an inevitability, since the Public Security Bureau couldn’t possibly watch all online activity within China, let alone block every objectionable web page worldwide. Interviewed by Wired magazine, the computer engineer overseeing the fanghuo qiang bluntly explained his working policy: “You make a problem for us, and we’ll make a law for you.” In many countries such a firewall might have stifled development, but most Chinese weren’t interested in making problems. They were attracted to the internet’s dazzling potential, as advertised on billboards that encouraged them to “join the internet club, meet today’s successful people, experience the spirit of the age, drink deep of the cup of leisure.” Those who could afford a connection, which cost approximately half the monthly salary of a recent college graduate, casually referred to the fanghuo qiang as the wangguan , calmly evoking the many guan (passes) of the Great Wall as natural features of China’s wan wei wang (ten-thousand-dimensional web).
Conference papers on the topic "Forbidden Blocks"
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Hussein, Mahmoud I., Massimo Ruzzene, Michael J. Leamy, Jason J. Durrie, and Bruce L. Davis. "NEMS Components Design Using Intentionally Defected Dispersive Building Blocks." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68246.
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We propose a hierarchical approach for the design of NEMS components with favorable dynamical characteristics. The approach consists of two steps: (i) design of several defect-engineered crystalline materials through intentional introduction of uniformly distributed defects, and in doing so altering precisely the frequency band structure of these materials, and (ii) allocation of patches of these designed materials to various regions in the component. Through this multiscale dispersive design approach, NEMS components can be designed to act as filters forbidding the transmission of vibrations at certain frequencies or waveguides confining the flow of energy to predetermined paths. Case studies are presented for 1D and 2D nanostructures.
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West, Lawrence C., Janet L. Pan, Susan J. Walker, Roger J. Malik, and John F. Walker. "Inducing normally forbidden transitions within the conduction band of GaAs quantum wells." In Quantum Wells for Optics and Opto-Electronics. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/qwoe.1989.wb4.
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Recently, a new type of intersubband transition in GaAs quantum wells was observed by West and Eglash [1,2]. This transition differed from previous intersubband transitions [3] in that it had a direct, fully allowed, dipole between the envelope wavefunctions rather than the Bloch wavefunctions, was spectrally narrow, and temperature stable. This particular type of intersubband transition was termed a quantum well envelope subband (or state) transition “QWEST.” The Stark energy shift between the first and second conduction subbands in a GaAs quantum well was observed by Harwit and Harris [4]. Infrared detectors utilizing the QWEST have also been made [5] recently.
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Dallas, W. J., and W. Kullmann. "Imaging of biological currents from magnetic fields: simulation." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.thp4.
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Since our algorithm for reconstructing generating currents from magnetic-field measurements uses a vector-Fourier space description of the imaging process, we cast the simulation in these terms. Using the Maxwell equations for static fields, we synthesize the magnetic field which would be generated by a current density distribution. Because we use the discrete Fourier transform, care is taken to configure the current so that the continuity equation is satisfied. We also take into account the spatial-frequency warping and the special form of bounding functions that are required by the discretization. Once the field has been synthesized, a forbidden measurement region is blocked out (including the region occupied by the current source). Multiplicative noise in controlled quantity is mixed into the accessible measurement region. Our reconstruction algorithm is applied. The resulting image or image series is then displayed on a color video display unit.
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Erdogan, T., K. G. Sullivan, and D. G. Hall. "Spontaneous emission from radiating atoms in cylindrically and spherically symmetric periodic structures." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.fee3.
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Recently there has been considerable interest in the concept of a manufactured structure exhibiting a "photonic band gap"—an energy band in the electromagnetic spectrum for which wave propagation is isotropically forbidden. Conventional treatments have employed a Bloch-wave approach to explore the spectral and directional nature of wave propagation in multi-dimensional, translationally invariant, Cartesian periodic structures. Utilizing a classical model, we directly treat the interaction of a radiating dipole with the fields supported by cylindrical and spherical Bragg structures. These novel structures, which are not translationally invariant, are capable of effectively confining light emitted from a central, but finite-sized, region. The size of this region depends on both source and structure characteristics, including the modulation and radial extent of the Bragg structure. We examine the radiative lifetime variations and resonance frequency shifts associated with particular idealizations of the structure and source. The results presented are of fundamental and practical interest owing to the unique geometry of the considered Bragg structures, which have recently been realized as semiconductor laser resonators in the form of cylindrical waveguide diffraction gratings.
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Yablonovitch, Eli. "Photonic band structure." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.me1.
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By analogy to electron waves in a crystal, electromagnetic waves in a 3-D periodic dielectric structure should be described by band theory. The idea of photonic band structure1 is rapidly2–5 gaining acceptance. The concepts of reciprocal space, Brillouin zones, dispersion relations, Bloch wave functions, Van Hove singularities, etc., are now being applied to optical waves. If the depth of refraction index modulation is sufficient, a photonic band gap can exist. This is a frequency band in which electromagnetic modes, spontaneous emission, and zero point fluctuations are all absent. Indeed, a photonic band gap cam be essentially ideal provided the dielectric response is real and dissipationless. In addition to the obvious uses in atomic and laser physics, photonic band structure can now begin to play a role in microwave and millimeter wave electronics. Defects can be introduced into the otherwise perfect 3-D structures, creating electromagnetic donor modes and acceptor modes. Effectively, these defects are purely dielectric single-mode high-Q cavities suitable for a range of frequencies from microwaves to the visible. At the outset it was realized1 that a face-centered-cubic (FCC) array in real space would produce the most spherelike Brillouin zone in reciprocal space. This spherelike geometry increased the likelihood that a forbidden gap would overlap all the way around the surface of the Brillouin zone. But is was unclear what should be the shape in real space of the atoms in this FCC array. The history of this field has been a search for that optimal 3-D dielectric geometry, favored by nature and by Maxwell’s equations. During this same period, electronic band theorists began calculating photonic band structure. It rapidly became apparent that the familiar scalar wave band theory, so frequently used for electrons in solids, was in utter disagreement with experiment on photons.7–10 Recently3–5 a full vector-wave band theory became available, which not only agreed with experiment, it successfully highlighted some discrepancies in the experiment.
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Yablonovitch, E. "Photonic band structure: observation of an energy gap for light in 3-D periodic dielectric structures." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.fw6.
Full textAbstract:
By analogy to electron waves in a crystal, light waves in a 3-D periodic dielectric structure should be described by band theory. Recently, the idea of photonic band structure1 has been introduced. This means that the concepts of reciprocal space, Brillouin zones, dispersion relations, Bloch wave functions, Van Hove singularities, etc. must now be applied to optical waves. If the depth of index of refraction modulation is sufficient, a photonic band gap can exist. This is an energy band in which optical modes, spontaneous emission, and zero point fluctuations are all absent. Therefore, inhibited spontaneous emission can now begin to play a role in a semiconductors and solid-state electronics. It makes sense then to speak of photonic band structure and of a photonic reciprocal space, which has a Brillouin zone ~1000 times smaller than the Brillouin zone of the electrons. If the dielectric constant is periodically modulated in all three dimensions, it is possible to have a photonic band gap which overlaps the electronic band edge and for spontaneous electron-hole recombination to be rigorously forbidden. Indeed the photonic band gap is essentially ideal since the dielectric response can be real and dissipationless. It is interesting that the most natural real space structure for the optical medium is face centered cubic (fee), which is also the most famous atomic arrangement in crystals. The comparison between electronic and photonic band structure is revealing: (a) The underlying dispersion relation for electrons is parabolic, while that for photons is linear. (b) The angular momentum of electrons is 1/2, but the scalar wave approximation is frequently made; in contrast, photons have spin 1 and the vector wave character will likely play a major role in the band structure. (c) The band theory of electrons is only an approximation due to electron-electron repulsion, while photonic band theory is essentially exact since photon interactions are negligible.