Forbidden Zone Research Articles

The diffusivity–mobility ratio in heavily doped nonlinear optical, optoelectronic and related materials

We study the diffusivity–mobility ratio (DMR) in heavily doped nonlinear compounds forming band tails on the basis of a newly formulated electron dispersion law and III–V, ternary and quaternary materials form a special case of our generalized analysis. The complex nature of the energy spectrum and creation of a new forbidden zone is the consequence of anisotropic energy band constants and the interaction of the impurity atoms in the tails with spin–orbit splitting of valence bands for the other compounds. Analytically, the presence of non-removable poles in the dispersion relation of the undoped material creates the complex energy spectrum for the corresponding heavily doped sample. The DMR for the heavily doped II–VI, IV–VI and stressed materials has been studied. It has been found taking n-type CdGeAs 2,, Cd 3As 2, InAs, InSb, Hg 1− x Cd x Te, In 1− x Ga x As y P 1− y lattice matched to InP, CdS, PbTe, PbSnTe, Pb 1− x Sn x Se and stressed InSb as examples that the DMR increases with the increasing electron concentration with different numerical values and the nature of variations are totally band structure dependent. An experimental method of determining the DMR in heavily doped materials for arbitrary dispersion relations together with three applications in the area of material science in general has been suggested.

Propagation of light through a forbidden zone in chiral media

The particular features of the propagation of light in uniaxial chiral liquid crystals with a large pitch of the spiral are considered. There exist forbidden zones in these systems for fairly large angles of incidence of an extraordinary ray. On the one hand, this results in an efficient reflection of the wave from the zone boundary, and, on the other hand, this causes the wave to decay inside the zone. A case of narrow forbidden zones is studied, and it is shown that optical effects that arise upon propagation of rays near turning points are equivalent to the tunnel and over-barrier reflection effects. The angular dependences of the intensities of rays that were refracted in a forbidden zone and transmitted through it are calculated. The percolation effect is experimentally studied in a mixture of a nematic liquid crystal with a chiral addition. The intensity of a transmitted extraordinary ray is studied as a function of the angle of incidence, which determines the width of the forbidden zone. Both the over-barrier reflection and the percolation effects are observed. The calculation results are shown to agree with experiment.

Multi-objective decision making by reference point theory for a wellbeing economy

Traditionally, perhaps unconsciously, all multi-objective decision methods, reference point theory included, are situated in the production sphere. In production economics, it is quite common that measurement is done in a linear way. The consumption sphere asks for another approach. In the wellbeing economy consumer sovereignty is put central. Indifference Curves visualize the economic Law of Marginal Decreasing Utility on its turn the translation of consumer sovereignty. With reference point theory the danger exists that the Reference Point is situated above the highest possible indifference curve. In addition, a reference point will have a tendency to pull the discrete points of the alternatives into the forbidden zone, the target being to minimize the corresponding distances. The Minkowski Metric shows different forms of reference point theory, which are very unsatisfactory such as the Rectangular Distance Metric and the Euclidean Distance Metric. In this way, one can criticize all other values given to the Minkowsky metric too, with exception of infinity (the Min-Max Metric). Tests show that Min-Max normalized with ratio analysis is the most in concordance with indifference curves analysis.

Light propagation in chiral media with large pitch

Light propagation in uniaxial chiral media with large pitch is studied. In these systems there are forbidden zones for extraordinary beams, which lead to effective reflection on zone boundaries and to wave damping inside the forbidden zone. We analyze the vicinities of the turning points and the transition of an extraordinary wave through the forbidden zone. Narrow forbidden zones with merging turning points are studied in detail. The transition through the forbidden zone is studied experimentally in nematic liquid crystal doped with a chiral addition. There is a good agreement between experimental results and theoretical calculations.

Private Life in Stalin's Russia: Family Narratives, Memory and Oral History

For many years, we knew next to nothing about the private lives of 5 ordinary Soviet citizens during Stalin’s reign. Until very recently, the social history of the Soviet Union written by Soviet and Western historians alike was limited entirely to the public sphere – politics and ideology, and the collective experience of the ‘Soviet masses’. The individual (insofar as he or she appeared at all) featured mainly as a letter-writer to the Soviet 10 authorities (that is, as a public actor rather than a private person or member of a family). Sources were the obvious problem. Apart from a few memoirs by great writers, there was practically no reliable evidence about the private sphere of family life. For ordinary people in the Soviet Union, for the tens of millions 15 who suffered from repression, their family history was a forbidden zone of memory – something they would never talk or write about. During the Soviet period, the personal collections (lichnye fondy) built up in the state and Party archives belonged in the main to well-known public figures in the world of politics, science and culture; their documents 20 were carefully selected by their owners for donation to the state. The memoirs published in the Soviet Union were also generally unrevealing about the private experience of the people who wrote them, although there are some exceptions, particularly among those published in the glasnost

Features of light propagation in chiral media

Light propagation in uniaxial chiral liquid crystals with large pitch was studied. Vicinities of turning points were analyzed, and the effect of extraordinary wave transmission through bandgap layers was considered. It was shown that the description of wave transmission through the forbidden zone in the general case requires taking into account the existence of four singular points, two of which are responsible for the interaction of extraordinary rays and two points are responsible for the interaction of ordinary and extraordinary rays. Ray transmission in the case of wide bandgap layers was analyzed, when regions of applicability of the Wentzel-Kramers-Brillouin (WKB) approximation take place between singular points. The case of narrow bandgap layers, where singular points merge, was studied in detail. It was shown that the effect of ray transmission through such a zone and the above-barrier reflection effect is equivalent to the tunneling effect for the parabolic potential barrier. Angular dependences of the intensity of rays subject to internal refraction and transmitted through the bandgap layer were calculated. It was shown that the tunneling effect can be experimentally observed.

城市建设用地生态适宜性评价的 潜力—限制性分析 ——以大连城市化区为例

Ecological suitability assessment on land use is one of the fundamental works to use the limited land resources in China rationally.The conflict between urban land use and eco-environmental protection is very intense in the rapidly urbanized area,and it's important to do ecological suitability assessment on land use in such an area.Based on summing up the application of GIS technology,this study develops a domestic widely-used weighted factor-overlay method and extends it to a weighted potential-constrain approach which is originally from cost-benefit analysis.The main advantage of this approach is to divide the assessment factors into two groups,one contains ecological potential factors,and the other the ecological constrain factors,to choose the factors under the principle intensively of data obtainable,and to determine their weights by choosing exact means.The employment of this approach could help to determine the ecological suitability classes more scientifically and reasonably.In this study the potential-constrain approach is employed in Dalian city region,the analysis shows:(1) the area that could be intensively developed for urban construction purpose is 850.46 km2 in Dalian city region,being about 6.28% of the total study area;(2) the area that could be developed moderately for construction purpose is 1835.97 km2,or about 13.56% of the total area;and(3) the area that could not be used or being moderately and lightly suitable for construction is 10851.92 km2,or about 80.16% of the total area.Hence the land used for urban construction should be controlled under 20% of the region's total area,and the remaining 80% could not be used for urban development.Furthermore,based on the ecological suitability assessment,four planning zones of construction improvement zone,construction emphasized zone,construction restricted zone and construction forbidden zone could be worked out,in which the development strategies and implementations in each zone are suggested.The following aspects could be discussed in the application of the potential-constrain approach:(1) the resolution of satellitic image,which is the basic data,is one of the most important reasons affecting the precision of the result of assessment,according to different levels and different regional scopes,the right size of satellitic image should be chosen to keep balance between quality and quantity of the data dealt with;and(2) to the exactly assessment object,the factors chosen,the weight determined and the overlaying process should be all considered scientifically and reasonably.

Gas sensor applications of oxygen-ionic electrolytes: Development of their electron model

The objective of the present paper is to provide an electron model of the solid electrolytes with oxygen-ionic conductivity for gas sensors to simulate contact phenomena on the boundary of stabilized zirconia/metal electrode interface within the solid state zone theory. The primary focus of this article is modelling and assessment of the ability of yttria-stabilized zirconia (YSZ)-based solid electrolyte to control oxygen potentials at low temperatures in different environments. The proposed model allows the necessary information with regard to the electrolyte/metal electrode interface and about the character of the electronic conductivity to be obtained. The model also describes that the character of the electronic conductivity in solid electrolytes usually depends on two mechanisms of charge transfer: electrons transfer in the conductivity zone, separated from the valent zone in the solid electrolyte by the wide enough forbidden zone and the spasmodic transitions of electrons from one local level to another within the forbidden zone. Based on the proposed model, it was found that even the small traces of metallic admixtures in the solid oxygen-ionic electrolytes can substantially reduce the limits of the electrolytes applicability both by temperature and the level of measuring partial pressure.

Phenomenon of spontaneous loss of polarization in some porous dielectrics

Recently we have observed that porous CsI prepared by thermal evaporation spontaneouslyloses its polarization faculty with the elapse of time. In this paper the phenomenon ofspontaneous polarization faculty loss (SPFL) of porous CsBr is investigated and comparedwith that for porous CsI under the same experimental conditions. It is assumed that theSPFL phenomenon can be explained by structural modification of these porous materialsafter evaporation as well as by the decrease of their forbidden zone—analogously tocrystallization of Ge amorphous thin films prepared by vapour deposition and carbonnanotubes, respectively.

Tourism and "The Third Ear": Further Prospects for Qualitative Inquiry

This commentary on the state of the art of qualitative research in Tourism Studies is prompted and inspired by the recent appearance of Phillimore and Goodson's valuable coverage of the ontological and epistemological issues involved in the conduct of the enlarging body of qualitative research that has lately emerged in the field. It also stands as a follow-up article to the work of Jamal and Hollinshead in Tourism Management on similar matters. Like the latter, that is, that timely "Qualitative Research as a Forbidden Zone" article, this Tourism Analysis review article is premised upon the view that just as travel and tourism mirror so much of the social, communal, and political realities of the cultural world "out there," so research in Tourism Studies can mirror and much more advantageously utilize so many of the emergent phenomenological and ethnographic advances in research praxis that have followed in the wake of the so-called interpretive turn and the so-called literary turn of the human sciences. In viewing travel and tourism as critical and dynamic fields of seeing, being, experiencing, inventing, and knowing of and about the world, this review article positions travel and tourism as an inherently endlessly creative and mediating field of lived experience that, therefore, should be much more deeply explored interpretively, and thereby "qualitatively," in the light of the new insights that qualitative researchers have lately gained across human science disciplines into matters of meaning, textuality, and rhetorical power. Although The Forbidden Zone of Jamal and Hollinshead (in Tourism Management) explored the relevance of matters of "messy text," "confirmability," "engaged interestedness," and "locality" for Tourism Studies, this follow-up article here in Tourism Analysis peruses related questions of "text," "voice," "reflexivity," and "audience." It broadly concludes that—after Wichroski (1997)—the inexperienced qualitative researcher in travel/tourism/any domain can normally improve his or her sensibilities to the interpretive issues faced and to the contextual situation encountered by learning how to deploy "a third ear" to actively sense the involved difficult matters of "tacit" individual presence, "unstated" communal existence, and "undeclared" researcher power and authority in both the research locales and the investigative processes he/she is engaged in. Although this follow-up (Third Ear) article posits many strengths in the use of qualitative research in Tourism Studies—particularly in tapping the misty plurivocality of populations and the exacting, contested narratives about places and pasts—the endeavor to understand the different styles of interpretive/ethnographic/textual insight that course through various qualitative techniques is no soft option in research, and demands considerable sensitivity to the unfixities of meaning, affiliation, and identity. Overall then, as did Phillimore and Goodson, this Third Ear review article seeks to shift the debate about the merit and value of qualitative research beyond concerns of "technique" and away from the strictures of "method," per se, towards the need for the collective field of Tourism Studies to encourage more of its researchers towards flexible, interpretive approaches that demand enhanced situational use of their human intuitive and creative capacities themselves as a perceptual, diagnostic, and inferential resource. Thereby, the article calls for a more reasoned use of these sorts of creatively informed human capacities where they can be utilized sensitively in critical-vigorous fashion to gauge the held local/situational realities of and about the world, and with critical-rigor over the care in which those found understandings are reflexively captured and crosschecked. But the authors of this review article recognize that the new/emergent intersubjectivities and the new/unfolding moral discourse of qualitative inquiry are still rupturing, still messy, and (for many researchers) still a rather dark matter. As the field of Tourism Studies continues into the 21st century, there are so many new options and opportunities in the engagement with the ever-expanding portfolio of qualitative research approaches—but there is still so much to learn in situ about how each one of them may be sensibly and appropriately deployed in each of those specific research locales.

Construction of Vector of Gene Targeting to Multiple Loci for Leghorn Chicken Based on BAC with Cre/lox P System

Based on the sequence of BAC (Bacterial Artificial Chromosome) along with the Cre/lox P system, the gene-targeting vectors to multiple loci of the repetitive internal transcribed spacers between rDNA genes in Leghorn chicken were constructed. The main material of gene targeting to multiple loci in Leghorn chicken would be obtained. First, the plasmid of pYLSV-TDN with TK, HRDS2, and Neo genes was constructed. The TK-HRDS2- Neo DNA fragment obtained from the plasmid of pYLSV-TDN was digested by Not I/ Hind III and inserted into the upstream of the l ox P site of BAC plasmid for obtaining the selective vector of BAC-TDN. The expression vector of pYLVS-GID with EGFP, hIFN genes, and HRDS1 was then obtained. The plasmid of BAC-TDN-VS-GID was obtained by cotransformation of the selective vector of BAC-TDN and the expression vector of pYLVS-GID to E. coli NS3529 through the action of Cre/lox P system. The gene-targeting vector of BAC-TDN-GID to multiple loci of the ITS region in Leghorn chicken was obtained by cleaving the sequence of pYLVS with the homing endonuclease of I -Sce I and ligating with the linker of LS. The insertion and the insert direction of DNA fragments were identified by restriction digestion or PCR and sequencing in each clone. The significance of the technique of gene-targeting vector to multiple loci is shown as follows. First, the targeting loci were increased to 100–300. Second, the problems of unstable expression of inserted genes were partially solved. Third, the need for safety against toxicity integration was resolved. Fourth, the forbidden zone of gene integrating on the repetitive DNA sequences was broken through.

Copyrights and "Design-Around" Scholarship

A patent is a formidable thing. In the United States, it affords twenty years of nearly ironclad protection to an inventor who can prove, after considerable expenditure of time and money, that some new process for manufacturing widgets is a novel and non obvious addition to what legal practitioners call the prior art-?all those processes for manufacturing widgets that others have thought up in the past. Once the federal government has conferred a patent upon an inventor, competitors must have a care. A successful inven tion inspires imitation, but if the imitation is too close, its author may get slapped with a lawsuit. In the high-dollar world of patents, losing an infringement suit can mean facing damages of millions or even billions of dollars.1 So imitators have to be as ingenious as the inventors they seek to imitate/Patent law encourages such ingenuity by permitting a clever competitor to design around a patent in such a way as to create a product that is the functional equivalent of the protected idea but narrowly avoids entering the forbidden zone of infringement. Economic policy also favors design-arounds. While non-infringing copycat products may threaten patentees' revenues, they also make the marketplace more competitive and drive down the price of prod ucts?consequences that are widely considered to be socially desir able.2 It takes skill and legal acumen to come up with a successful design-around. Many have devoted their careers to brainstorming these legitimate knockoffs. The humanities are perhaps the last place we would expect to

Frequency Dependence of Oil Conductivity at High Pressure

Electric conductivity of materials is defined by a competition of several mechanisms of charge carrier movement: phoretic, ionic and electron‐hole jumping. The relative contribution of them is not constant when thermodynamic conditions are changing. Paraffine and naphtene hydrocarbons are typical dielectrics. Formation of supermolecular structures is accompanied by ordering of asphaltene‐resin and polyaromatic molecules. Solvate shells contain the molecules with less molecular masses. The disperse particle from the centre to periphery is characterized by reduction of conductivity from the values peculiar to “good” semiconductors in a nucleus, “average” in intermediate phase to typical for dielectrics in the disperse media. Threshold of the mobility of charge carriers is determined by temperature, pressure, strength of the external field, width of the forbidden zone, and nature of components of the disperse media and phase. Spectra of conductivity of model asphaltene solutions and Kumkolskaya oil in frequency range from 10−3 up to 106 Hz are measured for pressures up to 1 GPa in temperature interval from 250 to 320 K. Particularly at the analysis of spectra of conductivity the technique offered by Sheu and Mullins is used. Dependences were approximated by power‐law functions according to the concept of Jonscher's “the universal response.” Influence of pressure and temperature to the exponents is analyzed. Values of activation energy are determined. Received data can be useful for prognosis of oil phase behavior at high pressures.

Photon‐induced field desorption of NO from Rh

AbstractThe effect of an electric field on the NO photo‐desorption from Rh was investigated using a pulsed laser atom probe. Experiments were carried out at 78 K by irradiating a [111] oriented Rh field‐emitter tip and a Rh single crystal of 1.4 mm diameter at 6.4 eV and at 3.2 eV photon energy. The energies and masses of the emitted ions were evaluated from time‐of‐flight (ToF) measurements. For 6.4 eV irradiation of the Rh tip, a quadratic yield dependence on the laser fluence has been observed for NO. This is interpreted as a two‐photon ionization of field‐adsorbed NO; this is supported by the same behavior of O2 and Xe but at a comparatively lower yield. In cases where the ionization energy of the probed species (Ar, N2, CO) is higher than 12.8 eV no such effect is observed. Laser irradiation with 2.3 eV photons initiates thermally assisted field desorption of the species at a comparatively higher fluence. Ion energy analysis suggests re‐neutralization of NO+ in the forbidden zone, but the translational energy gained appears to be sufficient to overcome the desorption barrier and field ionizion at the critical distance becomes probable. At low laser fluence a weak linear photo‐desorption process has been detected, presumably caused by substrate‐mediated electronic excitation as a first step. In this model, the photo‐desorbed NO will subsequently be field‐ionized, and accelerated away by the field. For the Rh single crystal, NO photo‐desorption, with two‐photon ionization in a second step, is deduced as the most probable mechanism. Copyright © 2007 John Wiley & Sons, Ltd.

Pressures and Temperatures of Ultrahigh-Pressure Metamorphism: Implications for UHP Tectonics and H2O in Subducting Slabs

Kyanite-phengite eclogites can yield robust P-T equilibration conditions that do not depend on the ferrous/ferric ratios of the constituent minerals. Even rocks lacking kyanite or phengite—for which the ferrous/ferric ratios are calculated stoichiometrically—can yield equilibration conditions that differ by < 0.4 GPa. The range of robust P-T conditions for kyanite-phengite UHP eclogites is more restricted than that reported for eclogites generally, with most in the range 600-800°C and < 4 GPa; none fall in the "forbidden zone" defined by geothermal gradients of ≤ 5 K/km. Most UHP eclogites equilibrated at temperatures below the H2O-saturated solidus for crustal rocks. This is probably because hotter UHP terranes are sufficiently low in viscosity that they mix with their surroundings and lose their identity or re-equilibrate continuously during cooling until the solidus is reached. Lawsonite and chloritoid are not known from UHP eclogites.

Light propagation in a helical medium with a large-scale periodicity

The propagation of light in helical media whose pitch greatly exceeds the radiation wavelength has been investigated. It is shown that such a system includes forbidden zones corresponding to the effect of ray turning. The propagation of an extraordinary ray corresponding to a very narrow forbidden zone has been analyzed in detail. The radiation wave field has been obtained both far from a turning point and in the close vicinity of such a point. It is shown that, in the vicinity of a turning point, mode transformation takes place and the wave acquires an elliptical polarization. The parameters of the ellipticity and the relations between the amplitudes of the waves passed through the forbidden zone and “reflected” from it are calculated.

Persistent transport barrier on the West Florida Shelf

Analysis of drifter trajectories in the Gulf of Mexico has revealed the existence of a region on the southern portion of the West Florida Shelf (WFS) that is not visited by drifters that are released outside of the region. This so-called "forbidden zone" (FZ) suggests the existence of a persistent cross-shelf transport barrier on the southern portion of the WFS. In this letter a year-long record of surface currents produced by a Hybrid-Coordinate Ocean Model simulation of the WFS is used to compute Lagrangian coherent structures (LCSs), which reveal the presence of a persistent cross-shelf transport barrier in approximately the same location as the boundary of the FZ. The location of the cross-shelf transport barrier undergoes a seasonal oscillation, being closer to the coast in the summer than in the winter. A month-long record of surface currents inferred from high-frequency (HF) radar measurements in a roughly 60 km × 80 km region on the WFS off Tampa Bay is also used to compute LCSs, and these also reveal the presence of transient transport barriers. While the HF-radar-derived transport barriers cannot be unambiguously linked to the boundary of the FZ, this analysis does demonstrate the feasibility of monitoring transport barriers on the WFS using a HF-radar-based measurement system. The implications of a persistent cross-shelf transport barrier on the WFS for the development of harmful algal blooms on the shoreward side of the barrier are considered.

Bound and Dark Photonic States in Globular Photonic Crystals

Experimental and theoretical results of globular photonic crystals properties are presented. By using a simple one-dimensional model of glob-ular photonic crystals, we have obtained dispersion laws for three photonic branches. Dependencies of the group velocity and photonic effective mass from the wave vector have been analyzed. We have established that for photons, corresponding to the edge of photonic branch, velocity of moving goes to zero; such type photons we call slowtons. Coherent emission of slowtons may be generated inside globular photonic crystals if the energy of exciting photons outside the crystal is close to the edges of the forbidden zone (gap) of such a crystal. The conditions of dark and bound states existing and generating in globular photonic crystal have been established.

Optical absorption by a semiconductor in the presence of intense radiation fields

Motivated by a recent experiment, the author presents a theoretical study on optical absorption in a semiconductor subjected to pump and probe radiation fields. The electron and hole interactions with midinfrared pump and probe fields are considered and the absorption coefficient is calculated on the basis of a Boltzmann equation approach. It is found that the results obtained theoretically are in line with those observed experimentally and can be used to understand important experimental findings such as the optical absorption in the forbidden zone and the dependence of the absorption of the probe field on intensity and frequency of the pump field.

Simple theory of the density-of-states function in heavily doped non-linear optical and optoelectronic materials

We study theoretically the dispersion relation of the conduction electrons and the corresponding density-of-state (DOS) function in heavily doped non-linear optical, tetragonal, III–V, ternary and quaternary materials forming band tails. It has been found, taking CdGeAs 2, Cd 3As 2, InAs, In 1− x Ga x As y P 1− y lattice matched to InP and Hg 1− x Cd x Te as examples of the aforementioned materials that the complex nature of the energy spectrum, the oscillatory DOS for the negative values of the energy and the creation of a new forbidden zone is due to the presence of the crystal field splitting constant, the anisotropic effective electron mass and the anisotropic spin–orbit splitting for the tetragonal and non-linear optical materials and because of the interaction of the impurity atoms in the tails with the spin–orbit splitting of the valence bands for the other compounds. Analytically, the presence of non-removable poles in the dispersion relation of the undoped material creates the complex energy spectrum for the corresponding heavily doped sample and the solution of the Boltzmann transport equation will introduce new physical ideas and new experimental findings under different external conditions. The results of the perturbed III–V semiconductors whose unperturbed energy band structures are defined by the two band model of Kane and that of parabolic energy bands are special cases of our generalized analysis and no oscillations in the DOS are found in the aforementioned cases. The well-known results of the DOS for all materials in the absence of doping have also been obtained from the theoretical analysis under certain limiting conditions. This compatibility is the indirect test of our generalized formalism.