Philippe Bloch: Reducing distance between experiments and CERN
2009-01-01
With its unique combination of several hundred staff members and thousands of users from around the world sharing offices and physics data and profiting from mutually beneficial exchanges of know-how and expertise, the PH Department is a good example of a successful worldwide collaboration, set up as it was to construct and run the Laboratory’s physics experiments. The PH Depart-ment has always played host to thousands of users that contribute to CERN experiments and work on them, and whose numbers are set to grow in the years to come. With his long-standing experience as a user and then as the head of the CERN group within the CMS collaboration, Philippe Bloch, the new PH Department Head, is in favour of closer links between the Department and the experiments. "I think that the PH management should have a direct link to the experiments, and to do so we are holding regular management team meetings comprising members of the Department’s management and the e...
Producing Knowledge to Reduce Rhetorical Distance
DEFF Research Database (Denmark)
Kampf, Constance
foot, the radio an extension of the ear, the television an extension of the eye. From this perspective, exploring the internet as an extension of identity produces fruitful questions about the role of on-line writing in Web presences. The Web changes writing as a knowledge-making practice by offering......Producing Knowledge to Reduce Rhetorical Distance: Extending Identity and Engaging Mainstream Ideology via the Web Constance Kampf, Department of Research Knowledge Communication, Aarhus School of Business, Denmark McLuhan describes technologies as extensions -the wheel being an extension of the...... writers a larger public forum into which they can extend their identity. When the identity being extended represents a minority group, the web offers an opportunity for members of that group to engage mainstream ideology and work at reducing the rhetorical distance between their identity and mainstream...
Hao, Hui-Qin; Zhang, Jian-Wen
2015-05-01
In this paper, we investigate the inhomogeneous reduced Maxwell-Bloch system, which describes the propagation of the intense ultra-short optical pulses through an inhomogeneous two-level dielectric medium. Through symbolic computation, the integrability aspects including the Painlevé integrable condition, Lax pair and infinite conservation laws are derived. By virtue of the Darboux transformation method, one- and two-soliton solutions are generated on the nonvanishing background, including the bright solitons, dark solitons, periodic solutions and some two-soliton solutions. The asymptotic analysis method is performed to verify the elastic interaction between two solitons. Furthermore, by virtue of some figures, the dynamic properties of those solitons are discussed. The results may be useful in the study of the ultrashort pulses propagation in such situations as the model of the two-level dielectric media.
Effectiveness of small barriers as means to reduce clearance distances
Energy Technology Data Exchange (ETDEWEB)
Tchouvelev, Andrei V.; Cheng, Zhong [A.V.Tchouvelev and Associates, 6591 Spinnaker Circle, Mississauga, Ont. (Canada); Agranat, Vladimir M. [Hydrogenics Corp., 5985 McLaughlin Road, Mississauga, Ont. (Canada); Zhubrin, Serguei V. [Flowsolve Limited, 130 Arthur Road, London SW19 8AA (United Kingdom)
2007-07-15
Hydrogen clearance or safety distance can be defined as the minimum distance between a hydrogen leak source and surrounding equipment, property or personnel beyond which the risk to the said recipients associated with existing hydrogen hazards is deemed acceptable. The same principal is applied to determine clearances to ignition sources and air intakes only the criteria in this case are the risk of ignition or the risk of intaking a flammable mixture. The study of effects of small barriers as means to reduce clearance distances for compressed hydrogen releases is important for the development of installation codes and risk mitigation requirements. In this paper, computational fluid dynamics (CFD) modeling techniques were applied to the numerical simulation of the effects of a protective wall of 1 m by 1 m on reducing the size of hydrogen cloud. The protective wall was 1 m away from a 70 MPa (700 bar) 60 L tank, from which an incidental hydrogen release impinged horizontally onto the wall, causing a complicated 3D dispersion of hydrogen cloud. In-house CFD codes first accurately estimated the non-linear hydrogen mass release rate decreasing with time. Then the effects of the wall on the propagation speed of the hydrogen cloud moving behind the wall were investigated using the PHOENICS software package, provided with both the ideal gas law and the real gas law expressed by the Abel-Nobel equation of state (AN-EOS). The distributions of lower flammability limit (LFL) and 50% of LFL hydrogen clouds were described in detail based on the numerical results. It was found that the 50% of LFL hydrogen clouds (2% vol) could propagate behind the wall in less than 0.2 s after the onset of the release. The horizontal extents corresponding to 50% of LFL hydrogen cloud on the central vertical plane are 9.6 m at 5 s when they are predicted using the ideal gas law. When using the real gas law, the predicted extents decrease to 6.3 m at 5 s. The ideal gas law significantly
Bloch-wave engineering of quantum dot-micropillars for cavity quantum electrodynamics experiments
DEFF Research Database (Denmark)
Lermer, Matthias; Gregersen, Niels; Dunzer, Florian;
2012-01-01
We have employed Bloch-wave engineering to realize submicron diameter ultra-high quality factor GaAs/AlAs micropillars (MPs). The design features a tapered cavity in which the fundamental Bloch mode is subject to an adiabatic transition to match the Bragg mirror Bloch mode. The resulting reduced ...
Quantum state transfer via Bloch oscillations
Tamascelli, Dario; Olivares, Stefano; Rossotti, Stefano; Osellame, Roberto; Paris, Matteo G. A.
2016-01-01
The realization of reliable quantum channels, able to transfer a quantum state with high fidelity, is a fundamental step in the construction of scalable quantum devices. In this paper we describe a transmission scheme based on the genuinely quantum effect known as Bloch oscillations. The proposed protocol makes it possible to carry a quantum state over different distances with a minimal engineering of the transmission medium and can be implemented and verified on current quantum technology hardware. PMID:27189630
The Bloch Oscillating Transistor
Seppä, H.; Hassel, J.
2003-01-01
We introduce a new mesoscopic transistor, which consists of a superconducting island connected to superconducting and normal electrodes via two mesoscopic tunnel junctions. Furthermore, the island is being charged through a resistor. The interplay between Bloch oscillations, single-electron effects and ohmic current leads to a device having a high current gain. The operation and characteristics of the transistor are analyzed with a numerical model.
Entangled Bloch Spheres: Bloch Matrix And Two Qubit State Space
Gamel, Omar
2016-01-01
We represent a two qubit density matrix in the basis of Pauli matrix tensor products, with the coefficients constituting a Bloch matrix, analogous to the single qubit Bloch vector. We find the quantum state positivity requirements on the Bloch matrix components, leading to three important inequalities, allowing us to parameterize and visualize the two qubit state space. Applying the singular value decomposition naturally separates the degrees of freedom to local and nonlocal, and simplifies the positivity inequalities. It also allows us to geometrically represent a state as two entangled Bloch spheres with superimposed correlation axes. It is shown that unitary transformations, local or nonlocal, have simple interpretations as axis rotations or mixing of certain degrees of freedom. The nonlocal unitary invariants of the state are then derived in terms of local unitary invariants. The positive partial transpose criterion for entanglement is generalized, and interpreted as a reflection, or a change of a single ...
Differential Bloch Oscillating Transistor Pair
Sarkar, Jayanta; Puska, Antti; Hassel, Juha; Hakonen, Pertti J.
2013-01-01
We examine a Bloch Oscillating Transistor pair as a differential stage for cryogenic low-noise measurements. Using two oppositely biased, nearly symmetric Bloch Oscillating Transistors, we measured the sum and difference signals in the current gain and transconductance modes while changing the common mode signal, either voltage or current. From the common mode rejection ratio we find values $\\sim 20$ dB even under non-optimal conditions. We also characterize the noise properties and obtain ex...
Surface Bloch waves mediated heat transfer between two photonic crystals
Ben-Abdallah, Philippe; Joulain, Karl; Pryamikov, Andrey
2010-01-01
submitted to Applied Physics Letters We theoretically investigate the non-radiative heat transfer between two photonic crystals separated by a small gap in non-equilibrium thermal situation. We predict that the surface Bloch states coupling supported by these media can make heat exchanges larger than those measured at the same separation distance between two massive homogeneous materials made with the elementary components of photonic crystals. These results could find broad applications i...
Bloch-Nordsieck cancellations beyond logarithms in heavy particle decays
Beneke, M.; Braun, Vladimir M.; Zakharov, V. I.
1994-01-01
We investigate the one-loop radiative corrections to the semileptonic decay of a charged particle at finite gauge boson mass. Extending the Bloch-Nordsieck cancellation of infrared logarithms, the subsequent non-analytic terms are also found to vanish after eliminating the pole mass in favor of a mass defined at short distances. This observation justifies the operator product expansion for inclusive decays of heavy mesons and implies that infrared effects associated with the summation of the ...
Wave impedance retrieving via Bloch modes analysis
DEFF Research Database (Denmark)
Andryieuski, Andrei; Ha, S.; Sukhorukov, A.; Malureanu, Radu; Kivshar, Y.; Lavrinenko, Andrei
-ciples violation, like antiresonance behaviour with Im(ε) <0, Im(μ) <0. We employ the Bloch mode analysis of periodic metamaterials to extract the dominating (fundamental) Bloch mode. Then it is possible to determine the Bloch and wave impedances by the surface and volume aver-aging of the electromagnetic field of...... the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance...
The Bloch Vector for N-Level Systems
Kimura, Gen
2003-01-01
We determine the set of the Bloch vectors for N-level systems, generalizing the familiar Bloch ball in 2-level systems. An origin of the structural difference from the Bloch ball in 2-level systems is clarified.
Marsee, Kevin; Tracey J. Woodruff; Axelrad, Daniel A.; Calafat, Antonia M.; Swan, Shanna H.
2006-01-01
Phthalate diesters have been shown to be developmental and reproductive toxicants in animal studies. A recent epidemiologic study showed certain phthalates to be significantly associated with reduced anogenital distance in human male infants, the first evidence of subtle developmental effects in human male infants exposed prenatally to phthalates. We used two previously published methods to estimate the daily phthalate exposures for the four phthalates whose urinary metabolites were statistic...
Electric dipoles on the Bloch sphere
Vutha, Amar C
2014-01-01
The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.
Electric dipoles on the Bloch sphere
Vutha, Amar C.
2015-03-01
The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic and molecular physics.
A theory of generalized Bloch oscillations
DEFF Research Database (Denmark)
Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny;
2016-01-01
Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact cal...
REDUCING THE COGNITIVE LOAD ON ANALYSTS THROUGH HAMMING DISTANCE BASED ALERT AGGREGATION
Directory of Open Access Journals (Sweden)
Peter Mell
2014-07-01
Full Text Available Previous work introduced the idea of grouping alert s at a Hamming distance of 1 to achieve lossless al ert aggregation; such aggregated meta-alerts were shown to increase alert interpretability. However, a mea n of 84023 daily Snort alerts were reduced to a still formidable 14099 meta-alerts. In this work, we add ress this limitation by investigating several approaches that all contribute towards reducing the burden on the analyst and providing timely analysis. We explore m inimizing the number of both alerts and data elemen ts by aggregating at Hamming distances greater than 1. We show how increasing bin sizes can improve aggregation rates. And we provide a new aggregation algorithm that operates up to an order of magnitud e faster at Hamming distance 1. Lastly, we demonstrat e the broad applicability of this approach through empirical analysis of Windows security alerts, Snor t alerts, netflow records, and DNS logs. The result is a reduction in the cognitive load on analysts by mini mizing the overall number of alerts and the number of data elements that need to be reviewed in order for an analyst to evaluate the set of original alerts.
Barefoot Running Reduces the Submaximal Oxygen Cost in Female Distance Runners.
Berrones, Adam J; Kurti, Stephanie P; Kilsdonk, Korey M; Cortez, Delonyx J; Melo, Flavia F; Whitehurst, Michael
2016-08-01
Berrones, AJ, Kurti, SP, Kilsdonk, KM, Cortez, DJ, Melo, FF, and Whitehurst, M. Barefoot running reduces the submaximal oxygen cost in female distance runners. J Strength Cond Res 30(8): 2348-2353, 2016-Being a competitive distance runner is, in part, attributable to a high V[Combining Dot Above]O2max. However, running economy (RE) is a more robust indicator of distance running performance among endurance athletes of similar V[Combining Dot Above]O2max levels. The purpose of this study was to examine the influence of unshod (barefoot) vs. shod (wearing shoes) running on RE (expressed as ml·kg·min) during three 5-minute submaximal running trials representing 65, 75, and 85% of V[Combining Dot Above]O2max. Other physiologic and perceptual variables such as respiratory exchange ratio, lactate, heart rate, and ratings of perceived exertion were also chosen as dependent variables. We measured V[Combining Dot Above]O2max in 14 recreationally active trained distance female runners (age = 27.6 ± 1.6 years; height = 163.3 ± 1.7 cm; weight = 57.8 ± 1.9 kg) who were completely inexperienced with unshod running. After initial testing, each subject was randomized to either unshod or shod for days 2 and 3. We analyzed the data with a 2-way (condition by intensity) repeated-measures analysis of variance. Submaximal oxygen consumption was significantly reduced at 85% of V[Combining Dot Above]O2max (p = 0.018), indicating an improvement in RE, but not during the 65% or 75% trials (p > 0.05, both). No other dependent measure was different between unshod and shod conditions. Our results indicate that the immediate improvement to RE while barefoot occurs at a relatively high fraction of maximal oxygen consumption. For the recreational or competitive distance runner, training or competing while barefoot may be a useful strategy to improve endurance performance. PMID:26808847
First Bloch eigenvalue in high contrast media
Briane, Marc; Vanninathan, Muthusamy
2014-01-01
This paper deals with the asymptotic behavior of the first Bloch eigenvalue in a heterogeneous medium with a high contrast ɛY-periodic conductivity. When the conductivity is bounded in L1 and the constant of the Poincaré-Wirtinger weighted by the conductivity is very small with respect to ɛ-2, the first Bloch eigenvalue converges as ɛ → 0 to a limit which preserves the second-order expansion with respect to the Bloch parameter. In dimension two the expansion of the limit can be improved until the fourth-order under the same hypotheses. On the contrary, in dimension three a fibers reinforced medium combined with a L1-unbounded conductivity leads us to a discontinuity of the limit first Bloch eigenvalue as the Bloch parameter tends to zero but remains not orthogonal to the direction of the fibers. Therefore, the high contrast conductivity of the microstructure induces an anomalous effect, since for a given low-contrast conductivity the first Bloch eigenvalue is known to be analytic with respect to the Bloch parameter around zero.
First Bloch eigenvalue in high contrast media
Energy Technology Data Exchange (ETDEWEB)
Briane, Marc, E-mail: mbriane@insa-rennes.fr [Institut de Recherche Mathématique de Rennes, INSA de Rennes (France); Vanninathan, Muthusamy, E-mail: vanni@math.tifrbng.res.in [TIFR-CAM, Bangalore (India)
2014-01-15
This paper deals with the asymptotic behavior of the first Bloch eigenvalue in a heterogeneous medium with a high contrast εY-periodic conductivity. When the conductivity is bounded in L{sup 1} and the constant of the Poincaré-Wirtinger weighted by the conductivity is very small with respect to ε{sup −2}, the first Bloch eigenvalue converges as ε → 0 to a limit which preserves the second-order expansion with respect to the Bloch parameter. In dimension two the expansion of the limit can be improved until the fourth-order under the same hypotheses. On the contrary, in dimension three a fibers reinforced medium combined with a L{sup 1}-unbounded conductivity leads us to a discontinuity of the limit first Bloch eigenvalue as the Bloch parameter tends to zero but remains not orthogonal to the direction of the fibers. Therefore, the high contrast conductivity of the microstructure induces an anomalous effect, since for a given low-contrast conductivity the first Bloch eigenvalue is known to be analytic with respect to the Bloch parameter around zero.
``Bloch wave'' modification of stimulated Raman by stimulated Brillouin scattering
Dodd, E. S.; Vu, H. X.; DuBois, D. F.; Bezzerides, B.
2013-03-01
Using the reduced-description particle-in-cell (RPIC) method, we study the coupling of backward stimulated Raman scattering (BSRS) and backward stimulated Brillouin scattering (BSBS) in regimes where the reflectivity involves the nonlinear behavior of particles trapped in the daughter plasma waves. The temporal envelope of a Langmuir wave (LW) obeys a Schrödinger equation where the potential is the periodic electron density fluctuation resulting from an ion-acoustic wave (IAW). The BSRS-driven LWs in this case have a Bloch wave structure and a modified dispersion due to the BSBS-driven spatially periodic IAW, which includes frequency band gaps at kLW˜kIAW/2˜k0 (kLW, kIAW, and k0 are the wave number of the LW, IAW, and incident pump electromagnetic wave, respectively). This band structure and the associated Bloch wave harmonic components are distinctly observed in RPIC calculations of the electron density fluctuation spectra and this structure may be observable in Thomson scatter. Bloch wave components grow up in the LW spectrum, and are not the result of isolated BSRS. Self-Thomson scattered light from these Bloch wave components can have forward scattering components. The distortion of the LW dispersion curve implies that the usual relationship connecting the frequency shift of the BSRS-scattered light and the density of origin of this light may become inaccurate. The modified LW frequency results in a time-dependent frequency shift that increases as the IAW grows, detunes the BSRS frequency matching condition, and reduces BSRS growth. A dependence of the BSRS reflectivity on the IAW Landau damping results because this damping determines the levels of IAWs. The time-dependent reflectivity in our simulations is characterized by bursts of sub-picosecond pulses of BSRS alternating with multi-ps pulses of BSBS, and BSRS is observed to decline precipitously as soon as SBS begins to grow from low levels. In strong BSBS regimes, the Bloch wave effects in BSRS are
REDUCING THE EFFECTS OF ISOLATION AND PROMOTING INCLUSIVITY FOR DISTANCE LEARNERS THROUGH PODCASTING
Directory of Open Access Journals (Sweden)
Anthony CHAN
2007-01-01
Full Text Available This article reports on an initiative to explore the potential of using supplementary audio podcast material to reduce the anxiety caused by isolation and to promote a sense of inclusivity amongst both undergraduate and postgraduate students studying an information technology subject in external mode with Australia’s largest provider of distance education. The podcasts were structured as a series of short, 3 to 5 minute talkback radio-style segments, with senior students holding discussions on pertinent issues related to the subject and its content in a relaxed and informal style. Both quantitative and qualitative data was obtained through a web-based survey conducted at the end of semester to gain insight into the views, experiences and perceived learning value of the podcasts from the perspective of the student listeners. Findings suggest that the approach was largely successful in achieving its aforementioned aims. In addition, the student listeners saw the podcasts as being especially effective in clarifying and enhancing their understanding of the subject; providing backup/reinforcement of what they had learnt; as well as supplying guidance on the direction in which to channel their study efforts. Overall, the authors believe podcasting has tremendous potential to assist in acculturating distance learners and aiding them in moving towards complete social and academic integration into institutional life, despite the presence of physical separation. The authors’ future research plans are also briefly outlined.
Claude Bloch scientific works, oeuvre scientifique
Bloch, Claude; De Dominicis, Cyrano; Gillet, Vincent; Messiah, Albert
1975-01-01
Claude Bloch: Scientific Works Oeuvre Scientifique covers the collection of scientific works of Claude Bloch. The book includes topics on field theories with non-localized interaction and notes on the symmetry properties of nuclear wave functions. It also covers theory of nuclear level density; the theory of imperfect fermi gases; the structure of nuclear matter; and the canonical form of an antisymmetric tensor and its application to the theory of superconductivity.
First Bloch eigenvalue in high contrast media
Briane, Marc; Vanninathan, Muthusamy
2014-01-01
16 pages International audience This paper deals with the asymptotic behavior of the first Bloch eigenvalue in a heterogeneous medium with a high contrast $\\varepsilon Y$-periodic conductivity. When the conductivity is bounded in $L^1$ and the constant of the Poincaré-Wirtinger weighted by the conductivity is very small with respect to $\\varepsilon^{-2}$, the first Bloch eigenvalue converges as $\\varepsilon\\to 0$ to a limit which preserves the second-order expansion with respect to the ...
MAGNIFY NETWORK LIFETIME IN WSN BY REDUCING DATA AGGREGATION DISTANCE OF WEAK NODES
Directory of Open Access Journals (Sweden)
Prashant Katoch
2015-12-01
Full Text Available Energy efficient protocols have always played a vital role in conservation of energy in Wireless Sensor Network. One of the major introduced protocols is LEACH a cluster based protocol. To improve its performance, an algorithm named as Maximizing the Network Lifetime of Clustered-based WSN Using Probability of Residual Energy is introduced. This protocol improved the Cluster Head selection process of LEACH by using the concept of residual energy. In the proposed paper, further improvement is done by enhancing the data transmission process. This process heightens the lifetime of the nodes having very less energy left by reducing their data transmission distance. Implemented results in MATLAB shows increase in the stability and lifetime of the network..
DEFF Research Database (Denmark)
Larsen, Gunvor Riber; Guiver, Jo W
2013-01-01
scales including cost, time and cultural difference to express relative distances. Some distances were seen as “zonal”, (e.g. “away from home” or “sun and sea” or winter sports destinations), others “ordinal”, having degrees of difference, time or costs to cross. The desire for distance also resulted...
Observation of Bloch oscillations in molecular rotation
Floß, Johannes; Averbukh, Ilya Sh; Bucksbaum, Philip H
2015-01-01
The periodically kicked quantum rotor is known for non-classical effects such as quantum localisation in angular momentum space or quantum resonances in rotational excitation. These phenomena have been studied in diverse systems mimicking the kicked rotor, such as cold atoms in optical lattices, or coupled photonic structures. Recently, it was predicted that several solid state quantum localisation phenomena - Anderson localisation, Bloch oscillations, and Tamm-Shockley surface states - may manifest themselves in the rotational dynamics of laser-kicked molecules. Here, we report the first observation of rotational Bloch oscillations in a gas of nitrogen molecules kicked by a periodic train of femtosecond laser pulses. A controllable detuning from the quantum resonance creates an effective accelerating potential in angular momentum space, inducing Bloch-like oscillations of the rotational excitation. These oscillations are measured via the temporal modulation of the refractive index of the gas. Our results int...
Fractional Bloch oscillations in photonic lattices
Corrielli, Giacomo; Della Valle, Giuseppe; Longhi, Stefano; Osellame, Roberto; 10.1038/ncomms2578
2013-01-01
Bloch oscillations, the oscillatory motion of a quantum particle in a periodic potential, are one of the most fascinating effects of coherent quantum transport. Originally studied in the context of electrons in crystals, Bloch oscillations manifest the wave nature of matter and are found in a wide variety of different physical systems. Here we report on the first experimental observation of fractional Bloch oscillations, using a photonic lattice as a model system of a two-particle extended Bose-Hubbard Hamiltonian. In our photonic simulator, the dynamics of two correlated particles hopping on a one-dimensional lattice is mapped into the motion of a single particle in a two-dimensional lattice with engineered defects and mimicked by light transport in a square waveguide lattice with a bent axis.
Sandwich reactor lattices and Bloch's theorem
International Nuclear Information System (INIS)
The study of the neutron flux distribution in repetitive sandwiches of reactor material leads to results analogous to the 1-dimensional form of Bloch's theorem for the electronic structure in crystals. This principle makes it possible to perform analytically accurate homogenisations of sandwich lattices The method has been extended to cover multi group diffusion and transport theory. (author)
Fractional Bloch Oscillations in photonic lattices
Directory of Open Access Journals (Sweden)
Corrielli G.
2013-11-01
Full Text Available We present the photonic analogy of the Fractional Bloch Oscillations [1]: the oscillatory motion of interacting particles moving in a periodic potential, under the presence of a static force. The analogy is implemented with the propagation of classical light in a specially engineered photonic waveguides lattice, fabricated in fused silica substrate via femtosecond laser micromachining.
Extended Cesaro Operator from to Bloch Space
Mingzhu Yang
2009-01-01
Let g be a holomorphic function of the unit ball B in several complex variables, and denote by the induced extended Cesaro operator. This paper discussed the boundedness and compactness of acting from to Bloch space in the unit ball.
Bloch mode synthesis: Ultrafast methodology for elastic band-structure calculations
Krattiger, Dimitri; Hussein, Mahmoud I.
2014-12-01
We present a methodology for fast band-structure calculations that is generally applicable to problems of elastic wave propagation in periodic media. The methodology, called Bloch mode synthesis, represents an extension of component mode synthesis, a set of substructuring techniques originally developed for structural dynamics analysis. In Bloch mode synthesis, the unit cell is divided into interior and boundary degrees-of-freedom, which are described, respectively, by a set of normal modes and a set of constraint modes. A combination of these mode sets then forms a reduced basis for the band structure eigenvalue problem. The reduction is demonstrated on a phononic-crystal model and a locally resonant elastic-metamaterial model and is shown to accurately predict the frequencies and Bloch mode shapes with a dramatic decrease in computation time in excess of two orders of magnitude.
Reduced walking speed and distance as harbingers of the approaching grim reaper.
Franklin, Barry A; Brinks, Jenna; Sacks, Roger; Trivax, Justin; Friedman, Harold
2015-07-15
Although treadmill exercise testing can provide an assessment of cardiorespiratory fitness, which serves as an independent prognostic indicator, numerous studies now suggest that usual gait speed, time, or distance covered during walk performance tests and weekly walking distance/time are powerful predictors of mortality and future cardiovascular events in selected patients. This review summarizes the relation between these variables and their association with cardiovascular and all-cause mortality, with specific reference to potential underlying mechanisms and implications for the clinician. Contemporary health care providers have escalating opportunities to promote lifestyle physical activity using pedometers, accelerometers, and smartphone-based health and wellness applications. In conclusion, fitness and/or ambulatory indexes should be considered a "vital sign" in middle-aged and older adults. PMID:25972052
Pogrebnyak, Victor A.; Furlani, Edward P.
2016-05-01
We study wave propagation in uniform materials with periodic boundary profiles and introduce for the first time Bloch resonances and Bloch gaps. Bloch resonances are due to transverse phase matching, i.e., the coupling of two transverse standing waves corresponding to different harmonics. These are distinct from well-known Bragg resonances that result from longitudinal phase matching. We show that Bloch gaps can be engineered over the entire first Brillouin zone up to an infinite wavelength, i.e., kx=0 , where kx is the wave number in the direction of propagation. This is in contrast to Bragg gaps that open at a fixed wavelength, twice the period of the structure. Bloch resonances and gaps can be tuned by reconfiguring the boundary profile and we derive analytical expressions that predict these phenomena when the amplitude of the profile is small. The theory is fundamental as it broadly applies to wave phenomena that span the quantum to continuum scale with applications that range from condensed matter to acoustics. We validate the theory experimentally for the electromagnetic field at GHz frequencies. We also discuss potential photonic and electronic applications of the theory such as a white-light distributed feedback laser and a two-dimensional electron gas transistor.
Pogrebnyak, Victor A; Furlani, Edward P
2016-05-20
We study wave propagation in uniform materials with periodic boundary profiles and introduce for the first time Bloch resonances and Bloch gaps. Bloch resonances are due to transverse phase matching, i.e., the coupling of two transverse standing waves corresponding to different harmonics. These are distinct from well-known Bragg resonances that result from longitudinal phase matching. We show that Bloch gaps can be engineered over the entire first Brillouin zone up to an infinite wavelength, i.e., k_{x}=0, where k_{x} is the wave number in the direction of propagation. This is in contrast to Bragg gaps that open at a fixed wavelength, twice the period of the structure. Bloch resonances and gaps can be tuned by reconfiguring the boundary profile and we derive analytical expressions that predict these phenomena when the amplitude of the profile is small. The theory is fundamental as it broadly applies to wave phenomena that span the quantum to continuum scale with applications that range from condensed matter to acoustics. We validate the theory experimentally for the electromagnetic field at GHz frequencies. We also discuss potential photonic and electronic applications of the theory such as a white-light distributed feedback laser and a two-dimensional electron gas transistor. PMID:27258880
Theory of the Bloch Oscillating Transistor
Hassel, J.; Seppa, H.
2004-01-01
The Bloch oscillating transistor (BOT) is a device, where single electron current through a normal tunnel junction can be used to enhance Cooper pair current in a mesoscopic Josephson junction leading to signal amplification. In this paper we develop a theory, where the BOT dynamics is described as a two-level system. The theory is used to predict current-voltage characteristics and small-signal response. Transition from stable operation into hysteretic regime is studied. By identifying the t...
International Nuclear Information System (INIS)
Partially reduced graphite oxide (GOpr) inherits expanded interlayer distance from the parent, graphite oxide (GO), and electronic conductivity from the grandparent, graphite. Indebted to the dual properties, GOpr shows unique behavior so-called electrochemical activation in organic electrolytes; when GOpr is polarized over a certain electrode potential, graphitic layers in GOpr are injected by solvated ions and become ion adsorbing sites permanently. Resultant gravimetric or volumetric capacitance (up to 200 F g−1 or 150 F ml−1) exceeds that of commercially available activated carbon electrodes for electric double-layer capacitor (EDLC). Previous literatures have reported that larger interlayer distance (d) lowers the on-set potential of electrochemical activation of graphitic carbons. However, the reason of this phenomenon has not yet been studied. In this paper, we combined experimental and theoretical approaches to reveal the effect of interlayer distance and van der Waals energy (UvdW) on the electrochemical activation of graphitic carbon. More specifically, we compared the energy for the electrochemical activation (UEA) and the van der Waals energy with respect to the interlayer distance. For this purpose, we devised an experimental method to measure UEA from cyclic voltammogram, and this method was verified by in-situ electrochemical dilatometry. The theoretical value of UvdW was calculated by semi-empirical density functional theory (DFT) and those experimental and theoretical values were linearly in accordance with each other. This finding signifies that (1) the electrochemical activation of graphitic carbon occurs by overcoming van der Waals energy to expand the interlayer distance, (2) and the on-set potential for electrochemical activation is varied by the interlayer distance because of the different van der Waals energy
A Refresher of the Original Bloch's Law Paper (Bloch, July 1885).
Gorea, Andrei
2015-08-01
In 1885, Adolphe-Moïse Bloch asked the following simple question "Is there a law describing the relationship between the duration of a light and its perceived intensity?" Based on a series of experiments using a Foucault regulator and a candle, Bloch concluded that "when the lighting duration varies from 0.00173 to 0.0518 seconds (…) the [visible] light is markedly in inverse proportion to its duration"-his famous law. As this law pertains to the more general and hotly debated question of accumulation of sensory information over time, it is timely to offer the public a full translation of Bloch's original paper (from French) and to present it within the context of contemporary research. PMID:27433317
Aggregates reduce transport distance of soil organic carbon: are our balances correct?
Directory of Open Access Journals (Sweden)
Y. Hu
2014-06-01
Full Text Available The effect of soil erosion on global carbon cycling, especially as a source or sink for greenhouse gases, has been the subject of intense debate. The controversy arises mostly from the lack of information on the fate of eroded soil organic carbon (SOC whilst in-transit from the site of erosion to the site of longer-term deposition. Solving this controversy requires an improved understanding of the transport distance of eroded SOC, which is principally related to the settling velocity of sediment fractions that carry the eroded SOC. Although settling velocity has already been included in some erosion models, it is often based on mineral particle size distribution. For aggregated soils, settling velocities are affected by their actual aggregate size rather than by mineral particle size distribution. Aggregate stability is, in turn, strongly influenced by SOC. In order to identify the effect of aggregation of source soil on the transport distance of eroded SOC, and its susceptibility to mineralization after transport and temporary deposition, a rainfall simulation was carried out on a silty loam. Both the eroded sediments and undisturbed soil were fractionated into six different size classes using a settling tube apparatus according to their settling velocities. Weight, SOC concentration and instantaneous respiration rates were measured for each of the six class fractions. Our results indicate that: (1 41% of the eroded SOC was transported with coarse aggregates that would be likely re-deposited down eroding hillslopes, rather than with fine particles likely transferred to water courses; (2 erosion was prone to accelerate the mineralization of eroded SOC, and thus might contribute more CO2 to the atmosphere than current estimates which often ignore potential effects of aggregation; (3 preferential deposition of SOC-rich coarse aggregates potentially causes an increase of SOC remaining in the colluvial system and a reduction of SOC flux to the
Bloch's Theorem in the Context of Quaternion Analysis
Gürlebeck, K
2012-01-01
The classical theorem of Bloch (1924) asserts that if $f$ is a holomorphic function on a region that contains the closed unit disk $|z|\\leq 1$ such that $f(0) = 0$ and $|f'(0)| = 1$, then the image domain contains discs of radius $3/2-\\sqrt{2} > 1/12$. The optimal value is known as Bloch's constant and 1/12 is not the best possible. In this paper we give a direct generalization of Bloch's theorem to the three-dimensional Euclidean space in the framework of quaternion analysis. We compute explicitly a lower bound for the Bloch constant.
Role of confined Bloch waves in the near field heat transfer between two photonic crystals
International Nuclear Information System (INIS)
The near field heat transfer between two finite size one-dimensional photonic crystals separated by a small vacuum gap and maintained in nonequilibrium thermal situation is theoretically investigated. The main features of this electromagnetic transfer are discussed and compared with what is generally observed with media that support surface polaritons. It is shown that the presence of surface Bloch waves can significantly enhance heat transfers beyond the far field limit for both polarization states of electromagnetic field at subwavelength separation distances. A specific attention is addressed to the consequence of the slopes of surface Bloch waves dispersion curves on the heat transfer. In particular, it is shown that the localization of surface Bloch waves close to the light line allows to observe a transfer exaltaion at larger separation distances than the Wien wavelength. These results could open new possibilities for the development of innovative near-field technologies such as near-field thermophotovoltaic conversion, plasmon assisted nanophotolitography or near-field spectroscopy.
Origin of the Bloch-type polarization components at the 180° domain walls in ferroelectric PbTiO3
International Nuclear Information System (INIS)
Determination of atomic and electronic structures of ferroelectric domain walls is crucial to understand and explore their unusual properties. Using first-principles calculations based on the density functional theory, we explored the atomic and electronic structures of 180° domain walls in PbTiO3, in order to understand the origin of Bloch-type polarization components. It is found that Bloch-type polarization components originate from the large displacements of Pb atoms and the Pb-O hybridization at the domain walls. The development of Bloch-type polarization components significantly reduce the domain wall energies and change the Peierls barriers of domain wall motion in different orientations
Bloch spaces on bounded symmetric domains in complex Banach spaces
Institute of Scientific and Technical Information of China (English)
DENG; Fangwen
2006-01-01
We give a definition of Bloch space on bounded symmetric domains in arbitrary complex Banach space and prove such function space is a Banach space. The properties such as boundedness, compactness and closed range of composition operators on such Bloch space are studied.
Improved Separability Criteria Based on Bloch Representation of Density Matrices.
Shen, Shu-Qian; Yu, Juan; Li, Ming; Fei, Shao-Ming
2016-01-01
The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for bipartite and multipartite quantum states. Theoretical analysis and some examples show that the proposed criteria can be more efficient than the previous related criteria. PMID:27350031
Bloch-Like Oscillations in Finite Quantum Structures
DEFF Research Database (Denmark)
Duggen, Lars; Willatzen, Morten; Lassen, Benny;
Inspired by several attempts to generate Bloch-like oscillations in different fields of physics [1,2], we examine a multitude of oscillator systems and interactions that lead to Bloch oscillations in finite quantum structures. A general requirement is the existence of a common period in the time ...
The ℋ∞ synchronization of nonlinear Bloch systems via dynamic feedback control approach
International Nuclear Information System (INIS)
We consider an ℋ∞ synchronization problem in nonlinear Bloch systems. Based on Lyapunov stability theory and linear matrix inequality formulation, a dynamic feedback controller is designed to guarantee asymptotic stability of the master-slave synchronization. Moreover, this controller reduces the effect of an external disturbance to the ℋ∞ norm constraint. A numerical example is given to validate the proposed synchronization scheme. (general)
Matveev, V. I.; Makarov, D. N.
2011-09-01
A simple method including nonperturbative shell corrections has been developed for calculating energy losses on complex atoms. The energy losses of fast highly charged ions on neon, argon, krypton, and xenon atoms have been calculated and compared with experimental data. It has been shown that the inclusion of the non-perturbative shell corrections noticeably improves agreement with experimental data as compared to calculations by the Bethe-Bloch formula with the standard corrections. This undoubtedly helps to reduce the number of fitting parameters in various modifications of the Bethe-Bloch formula, which are usually determined semiempirically.
“Bloch wave” modification of stimulated Raman by stimulated Brillouin scattering
International Nuclear Information System (INIS)
Using the reduced-description particle-in-cell (RPIC) method, we study the coupling of backward stimulated Raman scattering (BSRS) and backward stimulated Brillouin scattering (BSBS) in regimes where the reflectivity involves the nonlinear behavior of particles trapped in the daughter plasma waves. The temporal envelope of a Langmuir wave (LW) obeys a Schrödinger equation where the potential is the periodic electron density fluctuation resulting from an ion-acoustic wave (IAW). The BSRS-driven LWs in this case have a Bloch wave structure and a modified dispersion due to the BSBS-driven spatially periodic IAW, which includes frequency band gaps at kLW∼kIAW/2∼k0 (kLW, kIAW, and k0 are the wave number of the LW, IAW, and incident pump electromagnetic wave, respectively). This band structure and the associated Bloch wave harmonic components are distinctly observed in RPIC calculations of the electron density fluctuation spectra and this structure may be observable in Thomson scatter. Bloch wave components grow up in the LW spectrum, and are not the result of isolated BSRS. Self-Thomson scattered light from these Bloch wave components can have forward scattering components. The distortion of the LW dispersion curve implies that the usual relationship connecting the frequency shift of the BSRS-scattered light and the density of origin of this light may become inaccurate. The modified LW frequency results in a time-dependent frequency shift that increases as the IAW grows, detunes the BSRS frequency matching condition, and reduces BSRS growth. A dependence of the BSRS reflectivity on the IAW Landau damping results because this damping determines the levels of IAWs. The time-dependent reflectivity in our simulations is characterized by bursts of sub-picosecond pulses of BSRS alternating with multi-ps pulses of BSBS, and BSRS is observed to decline precipitously as soon as SBS begins to grow from low levels. In strong BSBS regimes, the Bloch wave effects in BSRS are
Unit quaternions and the Bloch sphere
International Nuclear Information System (INIS)
The spinor representation of spin-1/2 states can equally well be mapped to a single unit quaternion, yielding a new perspective despite the equivalent mathematics. This paper first demonstrates a useable map that allows Bloch-sphere rotations to be represented as quaternionic multiplications, simplifying the form of the dynamical equations. Left-multiplications generally correspond to non-unitary transformations, providing a simpler (essentially classical) analysis of time-reversal. But the quaternion viewpoint also reveals a surprisingly large broken symmetry, as well as a potential way to restore it, via a natural expansion of the state space that has parallels to second order fermions. This expansion to ‘second order qubits’ would imply either a larger gauge freedom or a natural space of hidden variables. (paper)
Bloch vector, disclination and exotic quantum holonomy
International Nuclear Information System (INIS)
A topological formulation of the eigenspace anholonomy, where eigenspaces are interchanged by adiabatic cycles, is introduced. The anholonomy in two-level systems is identified with a disclination of the director (headless vector) of a Bloch vector, which characterizes eigenprojectors. The covering map structure behind the exotic quantum holonomy and the role of the homotopy classification of adiabatic cycles are elucidated. The extensions of this formulation to nonadiabatic cycles and N-level systems are outlined. - Highlights: • A topological formulation of the eigenspace anholonomy is proposed. • The covering map structure behind the anholonomy is identified. • The role of homotopy classification of adiabatic cycles is explained. • The anholonomy in two-level systems is associated with disclinations. • The present formulation offers an extension to nonadiabatic cycles
Bloch state tomography using Wilson lines.
Li, Tracy; Duca, Lucia; Reitter, Martin; Grusdt, Fabian; Demler, Eugene; Endres, Manuel; Schleier-Smith, Monika; Bloch, Immanuel; Schneider, Ulrich
2016-05-27
Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high-energy theories, quantum information, and condensed-matter physics. In condensed-matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multiband systems. Using an ultracold gas of rubidium atoms loaded in a honeycomb optical lattice, we realize strong-force dynamics in Bloch bands that are described by Wilson lines and observe an evolution in the band populations that directly reveals the band geometry. Our technique enables a full determination of band eigenstates, Berry curvature, and topological invariants, including single- and multiband Chern and Z₂ numbers. PMID:27230376
Bloch state tomography using Wilson lines
Li, Tracy; Duca, Lucia; Reitter, Martin; Grusdt, Fabian; Demler, Eugene; Endres, Manuel; Schleier-Smith, Monika; Bloch, Immanuel; Schneider, Ulrich
2016-05-01
Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high-energy theories, quantum information, and condensed-matter physics. In condensed-matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multiband systems. Using an ultracold gas of rubidium atoms loaded in a honeycomb optical lattice, we realize strong-force dynamics in Bloch bands that are described by Wilson lines and observe an evolution in the band populations that directly reveals the band geometry. Our technique enables a full determination of band eigenstates, Berry curvature, and topological invariants, including single- and multiband Chern and Z2 numbers.
Unit quaternions and the Bloch sphere
Wharton, K. B.; Koch, D.
2015-06-01
The spinor representation of spin-1/2 states can equally well be mapped to a single unit quaternion, yielding a new perspective despite the equivalent mathematics. This paper first demonstrates a useable map that allows Bloch-sphere rotations to be represented as quaternionic multiplications, simplifying the form of the dynamical equations. Left-multiplications generally correspond to non-unitary transformations, providing a simpler (essentially classical) analysis of time-reversal. But the quaternion viewpoint also reveals a surprisingly large broken symmetry, as well as a potential way to restore it, via a natural expansion of the state space that has parallels to second order fermions. This expansion to ‘second order qubits’ would imply either a larger gauge freedom or a natural space of hidden variables.
Bloch inductance in small-capacitance Josephson junctions
Zorin, A. B.
2005-01-01
We show that the electrical impedance of a small-capacitance Josephson junction includes besides the capacitive term $-i/\\omega C_B$ also an inductive term $i\\omega L_B$. Similar to the known Bloch capacitance $C_B(q)$, the Bloch inductance $L_B(q)$ also depends periodically on the quasicharge $q$, and its maximum value achieved at $q=e (\\textrm{mod} 2e)$ always exceeds the value of the Josephson inductance of this junction $L_J(\\phi)$ at fixed $\\phi=0$. The effect of the Bloch inductance on ...
Bloch Inductance in Small-Capacitance Josephson Junctions
International Nuclear Information System (INIS)
We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/ωCB, an inductive term iωLB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(φ) at fixed φ=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described
Measuring h /mCs and the Fine Structure Constant with Bragg Diffraction and Bloch Oscillations
Parker, Richard
2016-05-01
We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations. In this new scheme, we have achieved a resolution of δα / α =0.25ppb in the fine structure constant measurement, which gives up to 4.4 million radians of phase difference between freely evolving matter waves. We suppress many systematic effects, e.g., Zeeman shifts and effects from Earth's gravity and vibrations, use Bloch oscillations to increase the signal and reduce the diffraction phase, simulate multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implement spatial filtering to further suppress systematic effects. We present our recent progress toward a measurement of the fine structure constant, which will provide a stringent test of the standard model of particle physics.
Interplay between Point-Group Symmetries and the Choice of the Bloch Basis in Multiband Models
Directory of Open Access Journals (Sweden)
Qiang-Hua Wang
2013-11-01
Full Text Available We analyze the point-group symmetries of generic multiband tight-binding models with respect to the transformation properties of the effective interactions. While the vertex functions in the orbital language may transform non-trivially under point-group operations, their point-group behavior in the band language can be simplified by choosing a suitable Bloch basis. We first give two analytically accessible examples. Then, we show that, for a large class of models, a natural Bloch basis exists, in which the vertex functions in the band language transform trivially under all point-group operations. As a consequence, the point-group symmetries can be used to reduce the computational effort in perturbative many-particle approaches, such as the functional renormalization group.
An approximation formula for the Bloch-Siegert shift of the Rabi model
Rapedius, K
2015-01-01
So far the Bloch-Siegert shift of the Rabi model has only been calculated numerically or by means of perturbation theory valid in either the weak or strong driving regime only. Recently Yan, L\\"u, and Zheng [Phys.~Rev.~A {\\bf 91}, 053834 (2015)] showed how to reduce the problem to solving a system of three nonlinear equations. Here, we pursue an alternative approach based on a perturbation expansion extrapolation technique. We are thus able to derive an explicit analytical approximation formula for the Bloch-Siegert shift of the Rabi model which is valid for all parameter regimes from weak to strong driving. Comparison with numerically exact results reveals an excellent agreement over the entire driving-strength range.
The Bloch wave operator: generalizations and applications: Part I. The time-independent case
Killingbeck, J P
2003-01-01
This is part 1 of a two-part review on wave operator theory and methods. The basic theory of the time-independent wave operator is presented in terms of partitioned matrix theory for the benefit of general readers, with a discussion of the links between the matrix and projection operator approaches. The matrix approach is shown to lead to simple derivations of the wave operators and effective Hamiltonians of Loewdin, Bloch, Des Cloizeaux and Kato as well as to some associated variational forms. The principal approach used throughout stresses the solution of the nonlinear equation for the reduced wave operator, leading to the construction of the effective Hamiltonians of Bloch and of Des Cloizeaux. Several mathematical techniques which are useful in implementing this approach are explained, some of them being relatively little known in the area of wave operator calculations. The theoretical discussion is accompanied by several specimen numerical calculations which apply the described techniques to a selection ...
Bloch-Floquet type waves in periodic ferromagnetic layered structure
Directory of Open Access Journals (Sweden)
Danoyan Z.N.
2014-06-01
Full Text Available The Bloch-Floquet type waves existence and propagation in ferromagnetic periodic layered structure are investigated. The dispersion equation obtained and investigated. It is shown that the waves spectrum contains forbidden zones.
Estimates on Bloch constants for planar harmonic mappings
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The Bloch constants for quasiregular harmonic mappings and open planar harmonic mappings are considered. Better estimates are obtained. The results, presented in this paper, improve the one made by Chen et al. and Grigoryan.
Bloch-mode analysis for effective parameters restoration
DEFF Research Database (Denmark)
Lavrinenko, Andrei; Andryieuski, Andrei; Ha, Sangwoo; Sukhorukov, Andrey A.; Kivshar, Yuri S.
surface or volume averaging of the electromagnetic fields of the dominating (fundamental) Bloch modes we are able to determine the Bloch and wave impedances, leading to wave and material effective parameters, respectively. The approach is demonstrated on several examples. We focus our discussion on the...... nature of microfields returned by Maxwell's solvers, showing that ignoring of difference between magnetic strength and induction lead to incorrect determination of the Poynting vector....
Intersubband gain in a Bloch oscillator and Quantum cascade laser
Willenberg, Harald; Dohler, Gottfried H.; Faist, Jerome
2002-01-01
The link between the inversion gain of quantum cascade structures and the Bloch gain in periodic superlattices is presented. The proposed theoretical model based on the density matrix formalism is able to treat the gain mechanism of the Bloch oscillator and Quantum cascade laser on the same footing by taking into account in-plane momentum relaxation. The model predicts a dispersive contribution in addition to the (usual) population-inversion-dependent intersubband gain in quantum cascade stru...
Calculation of the relativistic Bloch correction to stopping power
Ahlen, S. P.
1982-01-01
Bloch's technique of joining the nonrelativistic Bethe and Bohr stopping-power expressions by taking into account wave-packet effects for close collisions is extended to the relativistic case. It is found that Bloch's nonrelativistic correction term must be modified and that charge asymmetric terms appear. Excellent agreement is observed by comparing the results of these calculations to recent data on the stopping power of relativistic heavy ions.
Bloch oscillations of bosonic lattice polarons
Grusdt, F.; Shashi, A.; Abanin, D.; Demler, E.
2014-12-01
We consider a single-impurity atom confined to an optical lattice and immersed in a homogeneous Bose-Einstein condensate (BEC). Interaction of the impurity with the phonon modes of the BEC leads to the formation of a stable quasiparticle, the polaron. We use a variational mean-field approach to study dispersion renormalization and derive equations describing nonequilibrium dynamics of polarons by projecting equations of motion into mean-field-type wave functions. As a concrete example, we apply our method to study dynamics of impurity atoms in response to a suddenly applied force and explore the interplay of coherent Bloch oscillations and incoherent drift. We obtain a nonlinear dependence of the drift velocity on the applied force, including a sub-Ohmic dependence for small forces for dimensionality d >1 of the BEC. For the case of heavy impurity atoms, we derive a closed analytical expression for the drift velocity. Our results show considerable differences with the commonly used phenomenological Esaki-Tsu model.
Uriarte, María; Anciães, Marina; da Silva, Mariana T B; Rubim, Paulo; Johnson, Erik; Bruna, Emilio M
2011-04-01
Seed dispersal is a crucial component of plant population dynamics. Human landscape modifications, such as habitat destruction and fragmentation, can alter the abundance of fruiting plants and animal dispersers, foraging rates, vector movement, and the composition of the disperser community, all of which can singly or in concert affect seed dispersal. Here, we quantify and tease apart the effects of landscape configuration, namely, fragmentation of primary forest and the composition of the surrounding forest matrix, on individual components of seed dispersal of Heliconia acuminata, an Amazonian understory herb. First we identified the effects of landscape configuration on the abundance of fruiting plants and six bird disperser species. Although highly variable in space and time, densities of fruiting plants were similar in continuous forest and fragments. However, the two largest-bodied avian dispersers were less common or absent in small fragments. Second, we determined whether fragmentation affected foraging rates. Fruit removal rates were similar and very high across the landscape, suggesting that Heliconia fruits are a key resource for small frugivores in this landscape. Third, we used radiotelemetry and statistical models to quantify how landscape configuration influences vector movement patterns. Bird dispersers flew farther and faster, and perched longer in primary relative to secondary forests. One species also altered its movement direction in response to habitat boundaries between primary and secondary forests. Finally, we parameterized a simulation model linking data on fruit density and disperser abundance and behavior with empirical estimates of seed retention times to generate seed dispersal patterns in two hypothetical landscapes. Despite clear changes in bird movement in response to landscape configuration, our simulations demonstrate that these differences had negligible effects on dispersal distances. However, small fragments had reduced densities
Scanlan, Aaron T; Madueno, Maria C
2016-09-01
Scanlan, AT and Madueno, MC. Passive recovery promotes superior performance and reduced physiological stress across different phases of short-distance repeated sprints. J Strength Cond Res 30(9): 2540-2549, 2016-Limited research has examined the influence of recovery modalities on run-based repeated-sprint (RS) performance with no data available relative to the sprint phase. This study compared run-based RS performance across various sprint phases and underlying physiological responses between active and passive recoveries. Nine students (21.8 ± 3.6 years; 171.3 ± 6.4 cm; 72.8 ± 12.2 kg) completed 2 bouts (active and passive recoveries) of 10 × 20 m sprints interspersed with 30 s recoveries in a randomized crossover fashion. Sprint times and decrements were calculated for each split (0-5, 5-15, 15-20, and 0-20 m) across each sprint. Blood lactate concentration ([BLa]), heart rate (HR), and rating of perceived exertion (RPE) were measured at various time-points. Passive recovery promoted improved performance times (p ≤ 0.005) and decrements (p ≤ 0.045) across all splits, and lower post-test [BLa] (p ≤ 0.005), HR (bout 3 onwards) (p ≤ 0.014), and RPE (bout 4 onwards) when compared with active recovery. Performance differences between recoveries were less pronounced across the 0-5 m split. Temporal analyses showed significant (p ≤ 0.05) increases in sprint times and decrements primarily with active recovery. The present data indicate that passive recovery promoted superior performance across run-based RS, with earlier performance deterioration and greater physiological load evident during active recovery. These findings can aid the manipulation of interbout activity across RS drills to promote physiological overload and adaptation during training. Further, coaches may develop tactical strategies to overcome the detrimental effects of active recovery and optimize sprint performance in athletes during game-play. PMID:26808862
COMPOSITION OPERATORS ON THE LITTLE BLOCH SPACE IN POLYDISCS
Institute of Scientific and Technical Information of China (English)
Zhou Zehua; Zhu Min; Shi Jihuai
2005-01-01
Let Un be the unit polydisc of Cn and φ = (φ1,…,φn) a holomorphic self map of Un. This paper shows that the composition operator Cφ induced by φ is bounded on the little Bloch space β0*(Un) if and only if φ∈β0*(Un) for every l=1,2,…,n, and also gives a sufficient and necessary condition for the composition operator Cφ to be compact on the little Bloch spaceβ0* (Un).
Quantum Properties of Bloch Point as Nanosized Soliton in Ferromagnetics
Directory of Open Access Journals (Sweden)
M.Yu. Barabash
2014-11-01
Full Text Available It is established that magnetic soliton – Bloch point – has quantum properties which are manifested in the effects of tunneling and above-barrier reflection in a subhelium temperature range. The conditions of the given phenomena are determined.
Energy Technology Data Exchange (ETDEWEB)
Kozlowski, K.K.
2010-12-15
Starting from the form factor expansion in finite volume, we derive the multidimensional generalization of the so-called Natte series for the zero-temperature, time and distance dependent reduced density matrix in the non-linear Schroedinger model. This representation allows one to read-off straightforwardly the long-time/large-distance asymptotic behavior of this correlator. Our method of analysis reduces the complexity of the computation of the asymptotic behavior of correlation functions in the so-called interacting integrable models, to the one appearing in free fermion equivalent models. We compute explicitly the first few terms appearing in the asymptotic expansion. Part of these terms stems from excitations lying away from the Fermi boundary, and hence go beyond what can be obtained by using the CFT/Luttinger liquid based predictions. (orig.)
Dynamics of Bloch oscillating transistor near the bifurcation threshold
Sarkar, Jayanta; Puska, Antti; Hassel, Juha; Hakonen, Pertti J.
2013-01-01
The tendency to bifurcate can often be utilized to improve performance characteristics of amplifiers or even to build detectors. The Bloch oscillating transistor is such a device. Here, we show that bistable behavior can be approached by tuning the base current and that the critical value depends on the Josephson coupling energy EJ of the device. We demonstrate current-gain enhancement for the device operating near the bifurcation point at small EJ. From our results for the current gains at v...
Experimental reconstruction of Wilson lines in Bloch bands
Li, Tracy; Duca, Lucia; Reitter, Martin; Grusdt, Fabian; Demler, Eugene; Endres, Manuel; Schleier-Smith, Monika; Bloch, Immanuel; Schneider, Ulrich
2015-01-01
Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high energy theories, quantum information, and condensed matter physics. In condensed matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multi-band systems. By realizing strong-force dynamics in Bloch bands that are described by Wilson lines, we observe an ev...
Experimental reconstruction of Wilson lines in Bloch bands
Li, Tracy; Duca, Lucia; Reitter, Martin; Grusdt, Fabian; Demler, Eugene; Endres, Manuel; Schleier-Smith, Monika; BLOCH, Immanuel; Schneider, Ulrich
2015-01-01
Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high energy theories, quantum information, and condensed matter physics. In condensed matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multi-band systems. By realizing strong-force dynamics in Bloch bands that are described by Wilson lines, we observe an evolution of band po...
Super Bloch Oscillation in a PT symmetric system
Turker, Z
2016-01-01
Wannier-Stark ladder in a PT symmetric system is generally complex that leads to amplified/damped Bloch oscillation. We show that a non-amplified wave packet oscillation with very large amplitude can be realized in a non-Hermitian tight binding lattice if certain conditions are satisfied. We show that pseudo PT symmetry guarantees the reality of the quasi energy spectrum in our system.
International Nuclear Information System (INIS)
In combined proton-carbon fixed-nozzle treatment facilities with raster scanning delivery, the scattering of proton pencil beams caused by nozzle elements and the relatively large nozzle-to-isocenter distance cause a beam broadening. This may pose limitations to the achievable dose conformity. One way to counteract this effect is by delivering the treatment in a position closer to the nozzle than the room isocenter. Purpose of this study was to assess the potential dosimetric benefit of such solution, in terms of dose conformity and normal tissue sparing, in intensity-modulated proton therapy (IMPT) of intracranial tumors. For 12 patients with intracranial lesions, IMPT-plans were created at two treatment positions: nozzle-to-treatment-isocenter distance: 100 cm (room isocenter) and nozzle-to-treatment-isocenter distance: 60 cm. The resulting plans were compared in terms of dose distributions, dose-volume histograms and selected dosimetric indexes. With comparable target coverage, statistically significant normal tissue sparing was achieved through the reduction of the distance between nozzle and treatment isocenter. The decrease in mean dose (Dmean) was 12.5% to the whole brain, 16.2% to the brainstem, 9.7% and 15.4% to the temporal lobes, 10.0% and 12.9% to the hippocampi, 11.8% and 12.5% to the optic nerves and 0.2% to the chiasm. The volume receiving at least 10% of the prescribed dose (V10%) was reduced by more than 10% for most organs at risk (OARs). The maximum dose (Dnear-max) values to most OARs remained without significant difference. A reduced distance between nozzle and treatment isocenter leads to steeper lateral dose gradients and significantly reduces the volume of OARs adjacent to the target, which receives low to intermediate doses. Technical solutions shifting the treatment isocenter closer to the nozzle should be considered in clinical situations, where critical OARs are adjacent to the beam channel and where the integral dose should be minimized
Orbital magnetism of Bloch electrons I. General formula
International Nuclear Information System (INIS)
We derive an exact formula of orbital susceptibility expressed in terms of Bloch wave functions, starting from the exact one-line formula by Fukuyama in terms of Green's functions. The obtained formula contains four contributions: (1) Landau-Peierls susceptibility, (2) interband contribution, (3) Fermi surface contribution, and (4) contribution from occupied states. Except for the Landau-Peierls susceptibility, the other three contributions involve the crystal-momentum derivatives of Bloch wave functions. Physical meaning of each term is clarified. The present formula is simplified compared with those obtained previously by Hebborn et al. Based on the formula, it is seen first of all that diamagnetism from core electrons and Van Vleck susceptibility are the only contributions in the atomic limit. The band effects are then studied in terms of linear combination of atomic orbital treating overlap integrals between atomic orbitals as a perturbation and the itinerant feature of Bloch electrons in solids are clarified systematically for the first time. (author)
Behaviour of neutrons passing through the Bloch wall
International Nuclear Information System (INIS)
In part I of the present paper the pertinent knowledge about Bloch walls is presented and developed insofar as it appears necessary for the experiments with neutrons, that is to say the direction of magnetization within the domains, the calculation of the variation of magnetization in the wall, the wall thickness, and the zigzag structure of the Bloch wall. In part II it is first clarified why the Bloch wall can be treated as a continuum problem. It shows that this is possible far away from Laue reflexes. For angles far away from Laure-reflex angles the interaction of the periodic structure of the magnetization can be described with the aid of an averaged magnetic flux density. The consequence of it is the possibility of treating the problem by means of a Schroedinger equation with continous interaction. This leads to a law of refraction. The question of the possibilities for explaining the intensity behavior is treated in part III. This part, from different aspects, describes the fact, which already was pointed out in Schaerpf, O., Vehoff, H., Schwink, Ch. 1973, that the spin of the neutrons in passing through the wall is partly taken along by the magnetization gradually rotating in the wall. (orig./WBU)
Continuity, the Bloch-Torrey equation, and Diffusion MRI
Hall, Matt G
2016-01-01
The Bloch equation describes the evolution of classical particles tagged with a magnetisation vector in a strong magnetic field and is fundamental to many NMR and MRI contrast methods. The equation can be generalised to include the effects of spin motion by including a spin flux, which typically contains a Fickian diffusive term and/or a coherent velocity term. This form is known as the Bloch-Torrey equation, and is fundamental to MR modalities which are sensitive to spin dynamics such as diffusion MRI. Such modalities have received a great deal of interest in the research literature over the last few years, resulting in a huge range of models and methods. In this work we make make use of a more general Bloch-Torrey equation with a generalised flux term. We show that many commonly employed approaches in Diffusion MRI may be viewed as different choices for the flux terms in this equation. This viewpoint, although obvious theoretically, is not usually emphasised in the diffusion MR literature and points to inte...
Directory of Open Access Journals (Sweden)
Bernhard Streck
2012-10-01
Full Text Available The essay wants to deconstruct the genre of utopias so popular in the 20th century political writings. Human history shows manifold respect to stories about non-existent worlds which mix reality and non-reality, but outside the area of Abrahamitic beliefs there was rarely hope for a future. The secular version of such eschatological teachings begins with Karl Marx in the 19th century and culminates in the prophetic as well as revolutionary writings of Ernst Bloch around the terrible wars of the 20th century. This philosopher succeeded in both parts of post-war Germany and is still venerated inside and outside the academias. Compared with the so-called dystopias of Max Weber, Aldous Huxley or George Orwell the political visions of Bloch lack any sense of reality and seem to be quite useless to the understanding of present tendencies in world politics.
Zhou Zehua; Liu Yan
2006-01-01
Let be the unit polydisc of and a holomorphic self-map of . , and denote the -Bloch space, little -Bloch space, and little star -Bloch space in the unit polydisc , respectively, where . This paper gives the estimates of the essential norms of bounded composition operators induced by between ( or ) and ( or ). As their applications, some necessary and sufficient conditions for the (bounded) composition operators to be compact from ( or ) into ( or ) are obtained.
Properties of Floquet-Bloch space harmonics in 1D periodic magneto-dielectric structures
DEFF Research Database (Denmark)
Breinbjerg, O.
Recent years have witnessed a significant research interest in Floquet-Bloch analysis for determining the homogenized permittivity and permeability of metamaterials consisting of periodic structures. This work investigates fundamental properties of the Floquet-Bloch space harmonics in a 1-dimensi......-dimensional magneto-dielectric lossless structure supporting a transverse-electric-magnetic Floquet-Bloch wave; in particular, the space harmonic permittivity and permeability, as well as the space harmonic Poynting vector....
Experimental study of Bloch vector analysis in nonlinear, finite, dissipative systems
International Nuclear Information System (INIS)
We have investigated and experimentally demonstrated the applicability of the Bloch vector for one-dimensional, nonlinear, finite, dissipative systems. The case studied is the second harmonic generation from metallodielectric multilayer filters. In particular, we have applied the Bloch vector analysis to Ag/Ta2O5 thin-film multilayer samples and shown the importance of the phase matching calculated through the Bloch vector. The nonlinear coefficients extracted from experimental results are consistent with previous studies. Nowadays, metal-based nanostructures play a fundamental role in nonlinear nanophotonics and nanoplasmonics. Our results clearly suggest that even in these forefront fields the Bloch vector continues to play an essential role.
Excitation of Bloch-like surface waves in quasi-crystals and aperiodic dielectric multilayers.
Koju, Vijay; Robertson, William M
2016-07-01
The existence of Bloch surface waves in periodic dielectric multilayer structures with a surface defect is well known. Not yet recognized is that quasi-crystals and aperiodic dielectric multilayers can also support Bloch-like surface waves. In this work, we numerically show the excitation of Bloch-like surface waves in Fibonacci quasi-crystals and Thue-Morse aperiodic dielectric multilayers using the prism coupling method. We report improved surface electric field intensity and penetration depth of Bloch-like surface waves in the air side in such structures compared to their periodic counterparts. PMID:27367064
Dynamics of cold bosons in optical lattices: effects of higher Bloch bands
Łącki, Mateusz; Delande, Dominique; Zakrzewski, Jakub
2013-01-01
The extended effective multiorbital Bose-Hubbard-type Hamiltonian which takes into account higher Bloch bands is discussed for boson systems in optical lattices, with emphasis on dynamical properties, in relation to current experiments. It is shown that the renormalization of Hamiltonian parameters depends on the dimension of the problem studied. Therefore, mean-field phase diagrams do not scale with the coordination number of the lattice. The effect of Hamiltonian parameters renormalization on the dynamics in reduced one-dimensional optical lattice potential is analyzed. We study both the quasi-adiabatic quench through the superfluid-Mott insulator transition and the absorption spectroscopy, that is, the energy absorption rate when the lattice depth is periodically modulated.
Nonreciprocal Bloch Oscillations in Magneto-Optic Waveguide Arrays
Levy, Miguel
2010-01-01
We show that nonreciprocal optical Bloch-like oscillations can emerge in transversely magnetized waveguide arrays in the presence of an effective index step between the waveguides. Normal modes of the system are shown to acquire different wavenumbers in opposite propagation directions. Significant differences in phase coherence and decoherence between these normal modes are presented and discussed. Non-reciprocity is established by imposing unequal vertical refractive index gradients at the substrate/core, and core/cover interfaces in the presence of transverse magnetization.
Dynamics of Bloch oscillating transistor near bifurcation threshold
Sarkar, Jayanta; Puska, Antti; Hassel, Juha; Hakonen, Pertti J.
2013-01-01
Tendency to bifurcate can often be utilized to improve performance characteristics of amplifiers or even to build detectors. Bloch oscillating transistor is such a device. Here we show that bistable behaviour can be approached by tuning the base current and that the critical value depends on the Josephson coupling energy $E_J$ of the device. We demonstrate record-large current gains for device operation near the bifurcation point at small $E_J$. From our results for the current gains at vario...
Fast algorithm for periodic density fitting for Bloch waves
Lu, Jianfeng
2015-01-01
We propose an efficient algorithm for density fitting of Bloch waves for Hamiltonian operators with periodic potential. The algorithm is based on column selection and random Fourier projection of the orbital functions. The computational cost of the algorithm scales as $\\mathcal{O}\\bigl(N_{\\text{grid}} N^2 + N_{\\text{grid}} NK \\log (NK)\\bigr)$, where $N_{\\text{grid}}$ is number of spatial grid points, $K$ is the number of sampling $k$-points in first Brillouin zone, and $N$ is the number of bands under consideration. We validate the algorithm by numerical examples in both two and three dimensions.
Truncated-Bloch-wave solitons in optical lattices
Wang, Jiandong; Alexander, Tristram J; Kivshar, Yuri S
2009-01-01
We study self-trapped localized nonlinear states in the form of truncated Bloch waves in one-dimensional optical lattices, which appear in the gaps of the linear bandgap spectrum. We demonstrate the existence of families of such localized states which differ by the number of intensity peaks. These families do not bifurcate from the band edge, and their power curves exhibit double branches. Linear stability analysis demonstrates that in deep lattice potentials the states corresponding to the lower branches are stable, whereas those corresponding to the upper branches are unstable, independently of the number of peaks.
Traffic restrictions on Routes Bloch, Maxwell and Bohr
IT Department
2008-01-01
Excavation and pipework is being carried out in the framework of the transfer of the waste water treatment plant for the effluents from the surface treatment workshops from Building 254 to Building 676, currently under construction. This work may encroach onto Routes Bloch, Maxwell and Bohr and disrupt the flow of traffic. Users are requested to comply with the road signs that will be erected. The work is expected to last until the beginning of December 2008. Thank you for your understanding. TS/CE and TS/FM Groups Tel.7 4188 or 16 4314
A formula for the Bloch vector of some Lindblad quantum systems
Salgado, D; Sanchez-Gomez, J. L.
2003-01-01
Using the Bloch representation of an N-dimensional quantum system and immediate results from quantum stochastic calculus, we establish a closed formula for the Bloch vector, hence also for the density operator, of a quantum system following a Lindblad evolution with selfadjoint Lindblad operators.
A formula for the Bloch vector of some Lindblad quantum systems
International Nuclear Information System (INIS)
Using the Bloch representation of an N-dimensional quantum system and immediate results from quantum stochastic calculus, we establish a closed formula for the Bloch vector, hence also for the density operator, of a quantum system following a Lindblad evolution with selfadjoint Lindblad operators
From Bloch to random lasing in ZnO self-assembled nanostructures
DEFF Research Database (Denmark)
Garcia-Fernandez, Pedro David; Cefe, López
2013-01-01
In this paper, we present measurements on UV lasing in ZnO ordered and disordered nanostructures. Bloch lasing is achieved in the ordered structures by exploiting very low group-velocity Bloch modes in ZnO photonic crystals. In the second case, random lasing is observed in ZnO photonic glasses. W...
Wiegmann, P. B.; Zabrodin, A. V.
1993-01-01
We present a new approach to the problem of Bloch electrons in magnetic field,\\\\ by making explicit a natural relation between magnetic translations and the\\\\quantum group $U_{q}(sl_2)$. The approach allows to express the spectrum and\\\\\\ the Bloch function as solutions of the Bethe-Ansatz equations typical for com\\\\pletely integrable quantum systems
Bloch space structure, the qutrit wave function and atom-field entanglement in three-level systems
Sen, Surajit; Nath, Mihir Ranjan; Dey, Tushar Kanti; Gangopadhyay, Gautam
2011-01-01
We have given a novel formulation of the exact solutions for the lambda, vee and cascade three-level systems where the Hamiltonian of each configuration is expressed in the SU(3) basis. The solutions are discussed from the perspective of the Bloch equation and the atom-field entanglement scenario. For the semiclassical systems, the Bloch space structure of each configuration is studied by solving the corresponding Bloch equation and it is shown that at resonance, the eight-dimensional Bloch s...
Bloch-Zener oscillations in a tunable optical honeycomb lattice
Energy Technology Data Exchange (ETDEWEB)
Uehlinger, Thomas; Greif, Daniel; Jotzu, Gregor; Esslinger, Tilman [Institute for Quantum Electronics, ETH Zurich, 8093 Zurich (Switzerland); Tarruell, Leticia [Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland and LP2N, Universite Bordeaux 1, IOGS, CNRS, 351 cours de la Liberation, 33405 Talence (France)
2013-12-04
Ultracold gases in optical lattices have proved to be a flexible tool to simulate many different phenomena of solid state physics [1, 2]. Recently, optical lattices with complex geometries have been realized [3, 4, 5, 6, 7], paving the way to simulating more realistic systems. The honeycomb structure has recently become accessible in an optical lattice composed of mutually perpendicular laser beams. This lattice structure exhibits topological features in its band structure – the Dirac points. At these points, two energy bands intersect linearly and the particles behave as relativistic Dirac fermions. In optical lattices, Bloch oscillations [8] resolved both in time and in quasi-momentum space can be directly observed. We make use of such Bloch-Zener oscillations to probe the vanishing energy gap at the Dirac points as well as their position in the band structure. In small band gap regions, we observe Landau-Zener tunneling [7, 9] to the second band and the regions of maximum transfer can be identified with the position of the Dirac points.
The Quantum Noise of Ferromagnetic π-Bloch Domain Walls
Directory of Open Access Journals (Sweden)
Peter R. Crompton
2009-09-01
Full Text Available We quantify the probability per unit Euclidean-time of reversing the magnetization of a π-Bloch vector, which describes the Ferromagnetic Domain Walls of a Ferromagnetic Nanowire at finite-temperatures. Our approach, based on Langer’s Theory, treats the double sine-Gordon model that defines the π-Bloch vectors via a procedure of nonperturbative renormalization, and uses importance sampling methods to minimise the free energy of the system and identify the saddlepoint solution corresponding to the reversal probability. We identify that whilst the general solution for the free energy minima cannot be expressed in closed form, we can obtain a closed expression for the saddlepoint by maximizing the entanglement entropy of the system as a polynomial ring. We use this approach to quantify the geometric and non-geometric contributions to the entanglement entropy of the Ferromagnetic Nanowire, defined between entangled Ferromagnetic Domain Walls, and evaluate the Euclidean-time dependence of the domain wall width and angular momentum transfer at the domain walls, which has been recently proposed as a mechanism for Quantum Memory Storage.
Shu, Hong; Edwards, Geoffrey; Qi, Cuihong
2001-09-01
In geographic space, it is well known that spatial behaviors of humans are directly driven by their spatial cognition, rather than by the physical or geometrical reality. The cognitive distance in spatial cognition is fundamental in intelligent pattern recognition. More precisely, the cognitive distance can be used to measure the similarities (or relevance) of cognized geographic objects. In the past work, the physical or Euclidean distances are used very often. In practice, many inconsistencies are found between the cognitive distance and the physical distance. Usually the physical distance is overestimated or underestimated in the process of human spatial behaviors and pattern recognition. These inconsistencies are termed distance distortions. The aim of this paper is to illustrate the conceptions of cognitive distance and distance distortion. And if the cognitive distance is argued to be two-dimensional, it exists in heterogeneous space and the property of quasi-metric is shown. If the cognitive distance is multi-dimensional, it exists in homogeneous space and the property of metric is shown. We argue that distance distortions arise from the transformation of homogeneous to heterogeneous space and from the transformation of the two-dimensional cognitive distance to the multi-dimensional cognitive distance. In some sense, the physical distance is an instance of cognitive distance.
Entanglement and the three-dimensionality of the Bloch ball
Energy Technology Data Exchange (ETDEWEB)
Masanes, Ll., E-mail: ll.masanes@gmail.com [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Müller, M. P. [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Pérez-García, D. [Departamento de Analisis Matematico and IMI, Universidad Complutense de Madrid, 28040 Madrid (Spain); Augusiak, R. [ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona (Spain)
2014-12-15
We consider a very natural generalization of quantum theory by letting the dimension of the Bloch ball be not necessarily three. We analyze bipartite state spaces where each of the components has a d-dimensional Euclidean ball as state space. In addition to this, we impose two very natural assumptions: the continuity and reversibility of dynamics and the possibility of characterizing bipartite states by local measurements. We classify all these bipartite state spaces and prove that, except for the quantum two-qubit state space, none of them contains entangled states. Equivalently, in any of these non-quantum theories, interacting dynamics is impossible. This result reveals that “existence of entanglement” is the requirement with minimal logical content which singles out quantum theory from our family of theories.
Computation and visualization of photonic quasicrystal spectra via Blochs theorem
Rodriguez, Alejandro W; Avniel, Yehuda; Johnson, Steven G
2007-01-01
Previous methods for determining photonic quasicrystal (PQC) spectra have relied on the use of large supercells to compute the eigenfrequencies and/or local density of states (LDOS). In this manuscript, we present a method by which the energy spectrum and the eigenstates of a PQC can be obtained by solving Maxwells equations in higher dimensions for any PQC defined by the standard cut-and-project construction, to which a generalization of Blochs theorem applies. In addition, we demonstrate how one can compute band structures with defect states in the higher-dimensional superspace with no additional computational cost. As a proof of concept, these general ideas are demonstrated for the simple case of one-dimensional quasicrystals, which can also be solved by simple transfer-matrix techniques.
Engineering of slow Bloch modes for optical trapping
Energy Technology Data Exchange (ETDEWEB)
Milord, L.; Gerelli, E.; Jamois, C.; Harouri, A.; Benyattou, T., E-mail: taha.benyattou@insa-lyon.fr [Institut des Nanotechnologies de Lyon (INL), CNRS UMR5270, Université de Lyon, INSA-Lyon, Bât “Blaise Pascal,” 7 avenue Jean Capelle, Villeurbanne F-69621 (France); Chevalier, C.; Viktorovitch, P.; Letartre, X. [Institut des Nanotechnologies de Lyon (INL), CNRS UMR5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, Ecully F-69134 (France)
2015-03-23
In the present paper, we propose an approach based on slow Bloch mode microcavity that enables the optical trapping of small nanoparticles over a broad surface. A specific design based on a double-period photonic crystal is presented. It enables an easy coupling using a wide free-space Gaussian beam and the cavity Q factor can be tuned at will. Moreover, the microcavity mode is mainly localized within the photonic crystal holes, meaning that each hole of the microcavity behaves as efficient nanotweezers. Experimental studies have shown that 200 nm and 100 nm particles can be trapped within the microcavity, in a spatial region that corresponds to the size of one hole (200 nm wide). The experimental trap stiffness has been extracted. It shows that this approach is among the most performant ones if we take into account the size of the cavity.
Directory of Open Access Journals (Sweden)
Laura Ghigliotti
2015-11-01
Full Text Available The Greenland shark Somniosus microcephalus (Bloch and Schneider, 1801 is the largest predatory fish in Arctic waters. The socio-economic significance of Greenland shark is demonstrated by its impact on the fishing cultures in Greenland, Scandinavia and Iceland for centuries. The fundamental biology and ecological role of Greenland shark, on the other hand, is virtually unknown. Although knowledge of its life history is limited, increasing evidence indicates that the Greenland shark may undertake long-distance migrations and perform vertical movements from the surface to the deep sea. It is an omnivorous species feeding on carrion and a wide variety of pelagic and bottom-dwelling organisms ranging from invertebrates to mammals, and including active species such as fishes and seals. Accordingly, Greenland shark should be recognized as a top predator, with a strong potential to influence the trophic dynamics of the Arctic marine ecosystem. The sensory biology of Greenland shark is scarcely studied, and considering the importance of olfaction in chemoreception, feeding and other behavioral traits, we examined the architecture of the peripheral olfactory organ where olfactory cues are received from the environment – the olfactory rosette. The structural organization of the olfactory rosette, in terms of histological features of the sensory epithelium, number of primary lamellae and total sensory surface area, provides a first proxy of the olfactory capability of Greenland shark. Based on own results and published studies, the overall morphology of the olfactory rosette is viewed in context of the functional and trophic ecology among other elasmobranch species.
A Floquet-Bloch decomposition of Maxwell's equations, applied to homogenization
Sjöberg, Daniel; Engström, Christian; Kristensson, Gerhard; Wall, David J.N.; Wellander, Niklas
2003-01-01
Using Bloch waves to represent the full solution of Maxwell’s equations in periodic media, we study the limit where the material’s period becomes much smaller than the wavelength. It is seen that for steady-state ﬁelds, only a few of the Bloch waves contribute to the full solution. Effective material parameters can be explicitly represented in terms of dyadic products of the mean values of the non-vanishing Bloch waves, providing a new means of homogenization. The representa...
On Bloch approximation and the boundedness of integration operator on $H^\\infty$
Smith, Wayne; Stolyarov, Dmitriy M.; Volberg, Alexander
2016-01-01
We obtain a necessary and sufficient condition for the operator of integration to be bounded on $H^\\infty$ in a simply connected domain. The main ingredient of the proof is a new result on approximation of Bloch functions.
Spatiotemporal control of light by Bloch-mode dispersion in multi-core fibers
DEFF Research Database (Denmark)
Rasmussen, Per Dalgaard; Sukhorukov, A.A.; Neshev, D.N.;
2008-01-01
We study theoretically the dispersion properties of Bloch modes and nonlinearly-induced defect states in two-dimensional waveguide arrays. We define the conditions for achieving anomalous group-velocity dispersion and discuss possibilities for generation of spatiotemporal solitons....
A dorsal fold in Gymnura micrura (Bloch and Scheneider, 1801 (Chondrichthyes: Gymnuridae
Directory of Open Access Journals (Sweden)
Jorge Luiz Silva Nunes
2009-04-01
Full Text Available This paper reports a dorsal fold which is a membranous structure located on the tail of two juvenile butterfly rays, Gymnura micrura (Bloch & Scheneider, 1801, caught through artisanal fishery in the shallow waters of Maranhão State (Brazil.Neste manuscrito registra-se uma nadadeira dorsal em dois espécimes juvenis de Gymnura micrura (Bloch and Scheneider, 1801 capturadas pela pesca artesanal em águas rasas do estado do Maranhão (Brasil.
Weighted Composition Operators from Bergman-Type Spaces into Bloch Spaces
Indian Academy of Sciences (India)
Songxiao Li; Stevo Stević
2007-08-01
Let be an analytic self-map and be a fixed analytic function on the open unit disk in the complex plane $\\mathbb{C}$. The weighted composition operator is defined by $$u C_\\varphi f=u\\cdot p (f\\circ\\varphi), f\\in H(D).$$ Weighted composition operators from Bergman-type spaces into Bloch spaces and little Bloch spaces are characterized by function theoretic properties of their inducing maps.
Modified Bloch-Redfield Master Equation for Incoherent Excitation of Multilevel Quantum Systems
Tscherbul, Timur V.; Brumer, Paul
2014-01-01
We present an efficient theoretical method for calculating the time evolution of the density matrix of a multilevel quantum system weakly interacting with incoherent light. The method combines the Bloch-Redfield theory with a partial secular approximation for one-photon coherences, resulting in a master equation that explicitly exposes the reliance on transition rates and the angles between transition dipole moments in the energy basis. The modified Bloch-Redfield master equation allows an un...
Optimal cloning of qubits given by arbitrary axisymmetric distribution on Bloch sphere
Bartkiewicz, Karol; Miranowicz, Adam
2010-01-01
We find an optimal quantum cloning machine, which clones qubits of arbitrary symmetrical distribution around the Bloch vector with the highest fidelity. The process is referred to as phase-independent cloning in contrast to the standard phase-covariant cloning for which an input qubit state is a priori better known. We assume that the information about the input state is encoded in an arbitrary axisymmetric distribution (phase function) on the Bloch sphere of the cloned qubits. We find analyt...
Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices
Institute of Scientific and Technical Information of China (English)
GU Huai-Qiang; WANG Zhi-Cheng; JIN Kang; TAN Lei
2006-01-01
@@ We study the Bloch oscillations of two-component Bose-Einstein condensates trapped in spin-dependent optical lattices. The influence of the intercomponent atom interaction on the system is discussed in detail Accelerated breakdown of the Bloch oscillations and revival phenomena are found respectively for the repulsive and attractive case. For both the cases, the system will finally be set in a quantum self-trapping state due to dynamical instability.
An extended q-deformed su(2) algebra and the Bloch electron problem
Fujikawa, Kazuo; KUBO, HARUNOBU
1997-01-01
It is shown that an extended q-deformed $su(2)$ algebra with an extra (``Schwinger '') term can describe Bloch electrons in a uniform magnetic field with an additional periodic potential. This is a generalization of the analysis of Bloch electrons by Wiegmann and Zabrodin. By using a representation theory of this q-deformed algebra, we obtain functional Bethe ansatz equations whose solutions should be functions of finite degree. It is also shown that the zero energy solution is expressed in t...
Mohammad Razaz; Seyyed Ghodratollah Seifossadat; Morteza Razaz; Mahmood Joorabian
2015-01-01
This paper provides an algorithm of fault resistance compensation for digital ground distance relay considering the voltage and current transformer effects. Performance of the conventional ground distance relaying manner is adversely affected by different ground faults and also typical type, called a simultaneous open conductor and ground fault. The proposed scheme by using local-end data only, has shown satisfactory performances under wide variations in fault location, with different values ...
Geometry of the generalized Bloch sphere for qutrit
Goyal, Sandeep K; Singh, Rajeev; Simon, Sudhavathani
2011-01-01
The geometry of the generalized Bloch sphere $\\Omega_3$, the state space of a qutrit is studied. Closed form expressions for $\\Omega_3$, its boundary $\\partial \\Omega_3$, and the set of extremals $\\Omega_3^{\\rm ext}$ are obtained by use of an elementary observation. These expressions and analytic methods are used to classify the 28 two-sections and the 56 three-sections of $\\Omega_3$ into unitary equivalence classes, completing the works of earlier authors. It is shown, in particular, that there are families of two-sections and of three-sections which are equivalent geometrically but not unitarily, a feature that does not appear to have been appreciated earlier. A family of three-sections of obese-tetrahedral shape whose symmetry corresponds to the 24-element tetrahedral point group $T_d$ is examined in detail. This symmetry is traced to the reduction of the adjoint representation of SU(3), the symmetry underlying $\\Omega_3$, into direct sum of the two-dimensional and the two (inequivalent) three-dimensional ...
Allaire, Grégoire; Briane, Marc; Vanninathan, Muthusamy
2016-01-01
in press International audience In this paper we make a comparison between the two-scale asymptotic expansion method for periodic homogenization and the so-called Bloch wave method. It is well-known that the homogenized tensor coincides with the Hessian matrix of the first Bloch eigenvalue when the Bloch parameter vanishes. In the context of the two-scale asymptotic expansion method, there is the notion of high order homogenized equation [5] where the homogenized equation can be improve...
Hidden structures in time evolution of Bloch vector under thermal Jaynes-Cummings model
Azuma, Hiroo
2012-01-01
We reveal hidden structures of time evolution of the Bloch vector, whose dynamics is governed by the thermal Jaynes-Cummings model (JCM). Putting the two-level atom into a certain pure state and the cavity field into a mixed state in thermal equilibrium at initial time, we let the whole system evolve according to the JCM Hamiltonian. During this time evolution, the Bloch vector seems to be in complete disorder and confusion. Because of the thermal photon distribution, both its norm and direction change hard at random, so that the Bloch vector shows a quasichaotic behaviour. However, if we take a different viewpoint compared with ones that we have been used to, we can find some novel structures in the Bloch vector's trajectories plotted at constant time intervals. In this paper, at first, we try to give an explanation of emergence of the quasichaotic behaviour by drawing an analogy between the dynamics of the Bloch vector and that of a compressible fluid. Next, we discuss the following two facts: (1) If we adj...
Quasiperiodicity in time evolution of the Bloch vector under the thermal Jaynes-Cummings model
Azuma, Hiroo; Ban, Masashi
2014-07-01
We study a quasiperiodic structure in the time evolution of the Bloch vector, whose dynamics is governed by the thermal Jaynes-Cummings model (JCM). Putting the two-level atom into a certain pure state and the cavity field into a mixed state in thermal equilibrium at initial time, we let the whole system evolve according to the JCM Hamiltonian. During this time evolution, motion of the Bloch vector seems to be in disorder. Because of the thermal photon distribution, both a norm and a direction of the Bloch vector change hard at random. In this paper, taking a different viewpoint compared with ones that we have been used to, we investigate quasiperiodicity of the Bloch vector’s trajectories. Introducing the concept of the quasiperiodic motion, we can explain the confused behaviour of the system as an intermediate state between periodic and chaotic motions. More specifically, we discuss the following two facts: (1) If we adjust the time interval Δt properly, figures consisting of plotted dots at the constant time interval acquire scale invariance under replacement of Δt by sΔt, where s(>1) is an arbitrary real but not transcendental number. (2) We can compute values of the time variable t, which let |Sz(t)| (the absolute value of the z-component of the Bloch vector) be very small, with the Diophantine approximation (a rational approximation of an irrational number).
Probing the intrinsic optical Bloch-mode emission from a 3D photonic crystal.
Hsieh, Mei-Li; Bur, James A; Du, Qingguo; John, Sajeev; Lin, Shawn-Yu
2016-10-14
We report experimental observation of intrinsic Bloch-mode emission from a 3D tungsten photonic crystal at low thermal excitation. After the successful removal of conventional metallic emission (normal emission), it is possible to make an accurate comparison of the Bloch-mode and the normal emission. For all biases, we found that the emission intensity of the Bloch-mode is higher than that of the normal emission. The Bloch-mode emission also exhibits a slower dependence on [Formula: see text] than that of the normal emission. The observed higher emission intensity and a different T-dependence is attributed to Bloch-mode assisted emission where emitters have been located into a medium having local density of states different than the isotropic case. Furthermore, our finite-difference time-domain (FDTD) simulation shows the presence of localized spots at metal-air boundaries and corners, having intense electric field. The enhanced plasmonic field and local non-equilibrium could induce a strong thermally stimulated emission and may be the cause of our unusual observation. PMID:27606574
Directory of Open Access Journals (Sweden)
Mohammad Razaz
2015-03-01
Full Text Available This paper provides an algorithm of fault resistance compensation for digital ground distance relay considering the voltage and current transformer effects. Performance of the conventional ground distance relaying manner is adversely affected by different ground faults and also typical type, called a simultaneous open conductor and ground fault. The proposed scheme by using local-end data only, has shown satisfactory performances under wide variations in fault location, with different values of fault resistance and having positive and negative of power transfer angle. The presented method which has been carried out on the IEEE 14 bus benchmark is executed in PSCAD/EMTDC and MATLAB software, and the results show the accurate performance of mentioned configuration.
Hung, Yu-Ju; Lin, I-Sheng
2016-07-11
This paper reports a novel approach to the direct observation of Bloch surface waves, wherein a layer of fluorescent material is deposited directly on the surface of a semi-infinite periodic layered cell. A set of surface nano-gratings is used to couple pumping light to Bloch surface waves, while the sample is rotated until the pumping light meets the quasi-phase matching conditions. This study investigated the directional propagation of waves on stripe and circular one-dimensional grating structures by analyzing the dispersion relationship of the first two eigen modes. Our results demonstrate the efficacy of the proposed scheme in visualizing Bloch surface waves, which could be extended to a variety of other devices. PMID:27410869
Experimental realization of Bloch oscillations in a parity-time synthetic silicon photonic lattice
Xu, Ye-Long; Fegadolli, William S.; Gan, Lin; Lu, Ming-Hui; Liu, Xiao-Ping; Li, Zhi-Yuan; Scherer, Axel; Chen, Yan-Feng
2016-01-01
As an important electron transportation phenomenon, Bloch oscillations have been extensively studied in condensed matter. Due to the similarity in wave properties between electrons and other quantum particles, Bloch oscillations have been observed in atom lattices, photonic lattices, and so on. One of the many distinct advantages for choosing these systems over the regular electronic systems is the versatility in engineering artificial potentials. Here by utilizing dissipative elements in a CMOS-compatible photonic platform to create a periodic complex potential and by exploiting the emerging concept of parity-time synthetic photonics, we experimentally realize spatial Bloch oscillations in a non-Hermitian photonic system on a chip level. Our demonstration may have significant impact in the field of quantum simulation by following the recent trend of moving complicated table-top quantum optics experiments onto the fully integrated CMOS-compatible silicon platform. PMID:27095533
Experimental realization of Bloch oscillations in a parity-time synthetic silicon photonic lattice.
Xu, Ye-Long; Fegadolli, William S; Gan, Lin; Lu, Ming-Hui; Liu, Xiao-Ping; Li, Zhi-Yuan; Scherer, Axel; Chen, Yan-Feng
2016-01-01
As an important electron transportation phenomenon, Bloch oscillations have been extensively studied in condensed matter. Due to the similarity in wave properties between electrons and other quantum particles, Bloch oscillations have been observed in atom lattices, photonic lattices, and so on. One of the many distinct advantages for choosing these systems over the regular electronic systems is the versatility in engineering artificial potentials. Here by utilizing dissipative elements in a CMOS-compatible photonic platform to create a periodic complex potential and by exploiting the emerging concept of parity-time synthetic photonics, we experimentally realize spatial Bloch oscillations in a non-Hermitian photonic system on a chip level. Our demonstration may have significant impact in the field of quantum simulation by following the recent trend of moving complicated table-top quantum optics experiments onto the fully integrated CMOS-compatible silicon platform. PMID:27095533
Bloch wave deafness and modal conversion at a phononic crystal boundary
Directory of Open Access Journals (Sweden)
Vincent Laude
2011-12-01
Full Text Available We investigate modal conversion at the boundary between a homogeneous incident medium and a phononic crystal, with consideration of the impact of symmetry on the excitation of Bloch waves. We give a quantitative criterion for the appearance of deaf Bloch waves, which are antisymmetric with respect to a symmetry axis of the phononic crystal, in the frame of generalized Fresnel formulas for reflection and transmission at the phononic crystal boundary. This criterion is used to index Bloch waves in the complex band structure of the phononic crystal, for directions of incidence along a symmetry axis. We argue that within deaf frequency ranges transmission is multi-exponential, as it is within frequency band gaps.
Observation of Bloch oscillations in complex PT-symmetric photonic lattices
Wimmer, Martin; Christodoulides, Demetrios; Peschel, Ulf
2016-01-01
Light propagation in periodic environments is often associated with a number of interesting and potentially useful processes. If a crystalline optical potential is also linearly ramped, light can undergo periodic Bloch oscillations, a direct outcome of localized Wannier-Stark states and their equidistant eigenvalue spectrum. Even though these effects have been extensively explored in conservative settings, this is by no means the case in non-Hermitian photonic lattices encompassing both amplification and attenuation. Quite recently, Bloch oscillations have been predicted in parity-time-symmetric structures involving gain and loss in a balanced fashion. While in a complex bulk medium, one intuitively expects that light will typically follow the path of highest amplification, in a periodic system this behavior can be substantially altered by the underlying band structure. Here, we report the first experimental observation of Bloch oscillations in parity-time-symmetric mesh lattices. We show that these revivals ...
On averaging the Kubo-Hall conductivity of magnetic Bloch bands leading to Chern numbers
International Nuclear Information System (INIS)
The authors re-examine the topological approach to the integer quantum Hall effect in its original form where an average of the Kubo-Hall conductivity of a magnetic Bloch band has been considered. For the precise definition of this average it is crucial to make a sharp distinction between the discrete Bloch wave numbers k1, k2 and the two continuous integration parameters α1, α2. The average over the parameter domain 0 ≤ αj 1, k2. They show how this can be transformed into a single integral over the continuous magnetic Brillouin zone 0 ≤ αj j, j = 1, 2, nj = number of unit cells in j-direction, keeping k1, k2 fixed. This average prescription for the Hall conductivity of a magnetic Bloch band is exactly the same as the one used for a many-body system in the presence of disorder
Experimental realization of Bloch oscillations in a parity-time synthetic silicon photonic lattice
Xu, Ye-Long; Fegadolli, William S.; Gan, Lin; Lu, Ming-Hui; Liu, Xiao-Ping; Li, Zhi-Yuan; Scherer, Axel; Chen, Yan-Feng
2016-04-01
As an important electron transportation phenomenon, Bloch oscillations have been extensively studied in condensed matter. Due to the similarity in wave properties between electrons and other quantum particles, Bloch oscillations have been observed in atom lattices, photonic lattices, and so on. One of the many distinct advantages for choosing these systems over the regular electronic systems is the versatility in engineering artificial potentials. Here by utilizing dissipative elements in a CMOS-compatible photonic platform to create a periodic complex potential and by exploiting the emerging concept of parity-time synthetic photonics, we experimentally realize spatial Bloch oscillations in a non-Hermitian photonic system on a chip level. Our demonstration may have significant impact in the field of quantum simulation by following the recent trend of moving complicated table-top quantum optics experiments onto the fully integrated CMOS-compatible silicon platform.
Non-destructive monitoring of Bloch oscillations in an optical cavity
Keßler, H; Venkatesh, B P; Georges, Ch; Hemmerich, A
2016-01-01
Bloch oscillations are a hallmark of coherent wave dynamics in periodic potentials. They occur as the response of quantum mechanical particles in a lattice if a weak force is applied. In optical lattices with their perfect periodic structure they can be readily observed and employed as a quantum mechanical force sensor, for example, for precise measurements of the gravitational acceleration. However, the destructive character of the measurement process in previous experimental implementations poses serious limitations for the precision of such measurements. In this article we show that the use of an optical cavity operating in the regime of strong cooperative coupling allows one to directly monitor Bloch oscillations of a cloud of cold atoms in the light leaking out of the cavity. Hence, with a single atomic sample the Bloch oscillation dynamics can be mapped out, while in previous experiments, each data point required the preparation of a new atom cloud. The use of a cavity-based monitor should greatly impro...
The Barkas-Effect Correction to Bethe-Bloch Stopping Power
Porter, L. E.
A brief history of the discovery of the Barkas-effect correction to the Bethe-Bloch stopping power formula is presented, followed by a recounting of the initial theoretical calculations prepared as a quantitative explanation. A current version of the modified Bethe-Bloch formula is described in detail. An overview of the current capability to assess the validity of several existing formalisms for calculating the Barkas-effect correction term is provided, in the course of which discussion of numerous sources of uncertainty ensues. Finally, an opinion on the significance of this departure from Bethe-Bloch theory is offered, along with a presentation of a few recent developments and of some areas for focus in future exploration in the field of the stopping power of matter for charged particles.
Bloch wave deafness and modal conversion at a phononic crystal boundary
Laude, Vincent; Moiseyenko, Rayisa P.; Benchabane, Sarah; Declercq, Nico F.
2011-12-01
We investigate modal conversion at the boundary between a homogeneous incident medium and a phononic crystal, with consideration of the impact of symmetry on the excitation of Bloch waves. We give a quantitative criterion for the appearance of deaf Bloch waves, which are antisymmetric with respect to a symmetry axis of the phononic crystal, in the frame of generalized Fresnel formulas for reflection and transmission at the phononic crystal boundary. This criterion is used to index Bloch waves in the complex band structure of the phononic crystal, for directions of incidence along a symmetry axis. We argue that within deaf frequency ranges transmission is multi-exponential, as it is within frequency band gaps.
Bloch-like wave dynamics in disordered potentials based on supersymmetry
Yu, Sunkyu; Hong, Jiho; Park, Namkyoo
2015-01-01
Bloch's theorem for the description of waves in crystals was a major milestone, establishing the principle of bandgaps for electrical, optical, and vibrational waves. Although it was once believed that bandgaps could form only under conditions of periodicity and long-range correlations as the prerequisites for Bloch's theorem, this restriction was disproven by the groundbreaking discoveries of amorphous media and quasicrystals. While network and liquid models have been suggested for the interpretation of Bloch-like waves in disordered media, these approaches 'searching' for random networks with bandgaps have failed in the deterministic creation of bandgaps. Here, we reveal a deterministic pathway to bandgap engineering in disordered media, by applying the notion of supersymmetry to the fundamental wave equation. Inspired by the problem for isospectrality, we follow a methodology in stark contrast to previous methods: we 'transform' ordered potentials into disordered potentials while 'preserving' bandgaps. Our...
International Nuclear Information System (INIS)
The non-Bloch LCAO wave functions for cubic crystals are discussed and applied to the calculation of the matrix elements for electron transitions in an external electric field. The sum of transitions between non-Bloch electron states is compared with the matrix element for a conventional nearly free electron transition. 26 refs., 2 tabs
Sreekumari, T.; Aravindan, C.M.
1993-01-01
Satiation amount, satiation time and handling time of Anabas testudineus (Bloch), an air breathing predatory fish was experimentally estimated using guppy (Lebistes reticulatus) as prey. Weight of the fish and satiation time influenced prey handling time. As satiation time is related to the level of hunger, level of hunger was found to influence handling time of prey.
Floquet-Bloch waves and suppression of vibrations in multi-scale fluid-solid systems
Carta, Giorgio; Movchan, Alexander B
2016-01-01
The paper presents a mathematical model for an industry inspired problem of vibration isolation applied to a cluster of elastic fluid-filled containers. We develop a systematic approach employing full fluid-solid interaction and Floquet-Bloch waves in periodic multi-scale systems. The analytical findings are accompanied by numerical simulations, including frequency response analyses and computations in the transient regime.
Quantum Maxwell-Bloch equations for spontaneous emission in optical semiconductor devices
Hess, Ortwin; Hofmann, Holger F.
1998-01-01
We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous optical semiconductor devices taking into account the quantum noise effects which cause spontaneous emission and amplified spontaneous emission. Analytical expressions derived from the QMBE are presented for the spontaneous emission factor beta and the far field pattern of amplified spontaneous emission in broad area quantum well lasers.
Identification of Bloch-modes in hollow-core Photonic Crystal Fiber cladding
DEFF Research Database (Denmark)
Couny, F.; Benabid, F.; Roberts, John; Burnett, M.T.; Maier, S.A.
2007-01-01
We report on the experimental visualization of the cladding Bloch-modes of a hollow-core photonic crystal fiber. Both spectral and spatial field information is extracted using the approach, which is based on measurement of the near-field and Fresnel-zone that results after propagation over a short...
Decoherence of a qubit as a diffusion on the Bloch sphere
International Nuclear Information System (INIS)
We analyze qubit decoherence in the framework of geometric quantum mechanics. In this framework the qubit density operators are represented by probability distributions which are also the Kähler functions on the Bloch sphere. Interestingly, the complete positivity of the quantum evolution is recovered as ellipticity of the second order differential operator (deformed Laplacian) which governs the evolution of the probability distribution. (paper)
Thermal Two Point Function of a Heavy Muon in hot QED plasma within Bloch Nordsieck Approximation
Takashiba, K.
1995-01-01
The thermal propagator of a heavy muon propagating in a hot QED plasma is examined within the Bloch-Nordsieck approximation, which is valid in the infrared region. It is shown that the muon damping rate is finite, in contrast to the lower-order calculation with hard thermal loop resummations taken into account.
Dhar, Abhishek; Sriram Shastry, B.
2000-09-01
We present a calculation of the lowest excited states of the Heisenberg ferromagnet in 1D for any wave vector. These turn out to be string solutions of Bethe's equations with a macroscopic number of particles in them. They are identified as generalized quantum Bloch wall states, and a simple physical picture is provided for the same.
Dhar, Abhishek; Shastry, B. Sriram
2000-01-01
We present a calculation of the lowest excited states of the Heisenberg ferromagnet in 1-d for any wave vector. These turn out to be string solutions of Bethe's equations with a macroscopic number of particles in them. These are identified as generalized quantum Bloch wall states, and a simple physical picture provided for the same.
McQuinn, Kristen B W; Dolphin, Andrew E; Berg, Danielle; Kennicutt, Robert
2016-01-01
Great investments of observing time have been dedicated to the study of nearby spiral galaxies with diverse goals ranging from understanding the star formation process to characterizing their dark matter distributions. Accurate distances are fundamental to interpreting observations of these galaxies, yet many of the best studied nearby galaxies have distances based on methods with relatively large uncertainties. We have started a program to derive accurate distances to these galaxies. Here we measure the distance to M51 - the Whirlpool galaxy - from newly obtained Hubble Space Telescope optical imaging using the tip of the red giant branch method. We measure the distance modulus to be 8.58+/-0.10 Mpc (statistical), corresponding to a distance modulus of 29.67+/-0.02 mag. Our distance is an improvement over previous results as we use a well-calibrated, stable distance indicator, precision photometry in a optimally selected field of view, and a Bayesian Maximum Likelihood technique that reduces measurement unce...
Equity and Distance Education.
Ridge, Elaine; Waghid, Yusef
2001-01-01
Discusses how distance education can solve South Africa's problems of access to quality higher education, noting the need for radical shifts in perspective and sophisticated understanding of academic literacy. Explores key features of proposals by the Council on Higher Education (developing human capital and reducing high levels of structural…
International Nuclear Information System (INIS)
The University of Florida nuclear engineering sciences (NES) department has been active in distance learning since 1991, offering core courses for a master's degree in health physics through National Technological University (NTU) in conjunction with Colorado State University, University of Illinois, Georgia Institute of Technology, and Purdue University. In addition, the department has undertaken a long-distance lecture to Florida Junior College in Jacksonville and conducted joint research meetings with a research sponsor in Oak Ridge, Tennessee, utilizing the picture phones of AT ampersand T. The NES department is also under contract to the U.S. Department of Energy (DOE) to develop on-line training and maintenance modules for automated chemical analysis systems. These modules will be part of DOE's Office of Technology Development Contaminant Analysis Automation Program. For the education and training portion of the Contaminant Analysis Automation Program, the University of Florida is developing an on-line Human Computer Interface Training/Maintenance Module (HCI-T/MM) maintained at a central source, a computer server in the NES department
DEFF Research Database (Denmark)
Gaididei, Yu. B.; Christiansen, Peter Leth
2008-01-01
We study a parametrically driven Ginzburg-Landau equation model with nonlinear management. The system is made of laterally coupled long active waveguides placed along a circumference. Stationary solutions of three kinds are found: periodic Ising states and two types of Bloch states, staggered and...... unstaggered. The stability of these states is investigated analytically and numerically. The nonlinear dynamics of the Bloch states are described by a complex Ginzburg-Landau equation with linear and nonlinear parametric driving. The switching between the staggered and unstaggered Bloch states under the...
Institute of Scientific and Technical Information of China (English)
LIU Jing; LI Chunsheng; NING Ping
2013-01-01
Pampus cinereus (Bloch,1795) (Stromateidae),a species believed to be widely distributed throughout the Indo-Western Pacific region,was redescribed and a neotype was designated.The designation of a neotype was necessary because of ambiguous data in Bloch's original description and the loss of the original type specimen.Morphological data indicated that 10 recently-collected specimens from the coasts of southern China agreed well with Bloch's original description and figure ofP.cinereus.A neotype for this species was selected from among the 10 specimens,and a detailed description is presented in this paper.
Directory of Open Access Journals (Sweden)
DavidMEagleman
2013-02-01
Full Text Available A popular model for the representation of time in the brain posits the existence of a single, central clock. In that framework, temporal distortions in perception are explained by contracting or expanding time over a given interval. We here present evidence for an alternative account, one which proposes multiple independent timelines coexisting within the brain and stresses the importance of motor predictions and causal inferences in constructing our temporal representation of the world. Participants judged the simultaneity of a beep and flash coming from a single source at different distances. The beep was always presented at a constant delay after a motor action, while the flash occurred at a variable delay. Independent shifts in the implied timing of the auditory stimulus towards the motor action (but not the visual stimulus provided evidence against a central-clock model. Additionally, the hypothesis that the time between action and delayed effect is compressed (known as intentional binding seems unable to explain our results: firstly, because actions and effects can perceptually reverse, and secondly because the recalibration of simultaneity remains even after the participant’s intentional actions are no longer present. Contrary to previous reports, we also find that participants are unable to use distance cues to compensate for the relatively slower speed of sound when audio-visual events are presented in depth. When a motor act is used to control the distal event, however, adaptation to the delayed auditory signal occurs and subjective cross-sensory synchrony is maintained. These results support the hypothesis that perceptual timing derives from and is calibrated by our motor interactions with the world.
Serkin, Vladimir N.; Belyaeva, T. L.
2001-11-01
It is shown that optical solitons in nonlinear fibre-optic communication systems and soliton lasers can be represented as nonlinear Bloch waves in periodic structures. The Bloch theorem is proved for solitons of the nonlinear Schrodinger equation in systems with the dispersion, the nonlinearity, and the gain (absorption coefficient) periodically changing over the length. The dynamics of formation and interaction, as well as stability of the coupled states of nonlinear Bloch waves are investigated. It is shown that soliton Bloch waves exist only under certain self-matching conditions for the basic parameters of the system and reveal a structural instability with respect to the mismatch between the periods of spatial modulation of the dispersion, nonlinearity or gain.
Bloch oscillations as generators of polarons in a 1D crystal
Nazareno, H. N.; Brito, P. E. de
2016-08-01
The main purpose of this work is to characterize the kind of propagation/localization of carriers in a one-dimensional crystalline structure along the tight-binding model while the electron-phonon interaction is taken into account through a deformation potential and the system is under the action of a dc electric field. The lattice was treated in the classical formalism of harmonic vibrations. A remarkable effect is obtained due to the presence of the electric field. On one side the particle performs Bloch oscillations and at the same time it interacts with the lattice and as a result at each turning point of its trajectory phonons are generated that carry with them a fraction of the electronic wave packet, it is the polaron formation. This way the Bloch oscillations pump polarons into the system. We explain why the polaron is formed at returning points of the oscillations.
Quantum Theory of Conducting Matter Newtonian Equations of Motion for a Bloch Electron
Fujita, Shigeji
2007-01-01
Quantum Theory of Conducting Matter: Newtonian Equations of Motion for a Bloch Electron targets scientists, researchers and graduate-level students focused on experimentation in the fields of physics, chemistry, electrical engineering, and material sciences. It is important that the reader have an understanding of dynamics, quantum mechanics, thermodynamics, statistical mechanics, electromagnetism and solid-state physics. Many worked-out problems are included in the book to aid the reader's comprehension of the subject. The Bloch electron (wave packet) moves by following the Newtonian equation of motion. Under an applied magnetic field B the electron circulates around the field B counterclockwise or clockwise depending on the curvature of the Fermi surface. The signs of the Hall coefficient and the Seebeck coefficient are known to give the sign of the major carrier charge. For alkali metals, both are negative, indicating that the carriers are "electrons." These features arise from the Fermi surface difference...
Tilted resonators in a triangular elastic lattice: chirality, Bloch waves and negative refraction
Tallarico, Domenico; Movchan, Alexander B; Colquitt, Daniel J
2016-01-01
We consider a vibrating triangular mass-truss lattice whose unit cell contains a resonator of a triangular shape. The resonators are connected to the triangular lattice by trusses. Each resonator is tilted, i.e. it is rotated with respect to the triangular lattice's unit cell through an angle $\\vartheta_0$. This geometrical parameter is responsible for the emergence of a resonant mode in the Bloch spectrum for elastic waves and strongly affects the dispersive properties of the lattice. Additionally, the tilting angle $\\vartheta_0$ triggers the opening of a band gap at a Dirac-like point. We provide a physical interpretation of these phenomena and discuss the dynamical implications on elastic Bloch waves. The dispersion properties are used to design a structured interface containing tilted resonators which exhibit negative refraction and focussing, as in a "flat elastic lens".
Modified Bloch-Redfield Master Equation for Incoherent Excitation of Multilevel Quantum Systems
Tscherbul, Timur V
2014-01-01
We present an efficient theoretical method for calculating the time evolution of the density matrix of a multilevel quantum system weakly interacting with incoherent light. The method combines the Bloch-Redfield theory with a partial secular approximation for one-photon coherences, resulting in a master equation that explicitly exposes the reliance on transition rates and the angles between transition dipole moments in the energy basis. The modified Bloch-Redfield master equation allows an unambiguous distinction between the regimes of quantum coherent vs. incoherent energy transfer under incoherent light illumination. The fully incoherent regime is characterized by orthogonal transition dipole moments in the energy basis, leading to a dynamical evolution governed by a coherence-free Pauli-type master equation. The coherent regime requires non-orthogonal transition dipole moments in the energy basis, and leads to the generation of noise-induced quantum coherences and population-to-coherence couplings. As a fi...
Chaos synchronization in bi-axial magnets modeled by Bloch equation
International Nuclear Information System (INIS)
In this paper, we show that the bi-axial magnetic material modelled by Bloch equation admits chaotic solutions for a certain set of numerical values assigned to the system of parameters and initial conditions. Using the unidirectional linear and nonlinear feedback schemes, we demonstrate that two such systems can be synchronized together. The chaotic synchronization is discussed in the context of complete synchronization which means that the difference of the states of two relevant systems converge to zero. (author)
Laura Ghigliotti; Julius Nielsen; Jorgen Schou Christiansen; Eva Pisano
2015-01-01
The Greenland shark Somniosus microcephalus (Bloch and Schneider, 1801) is the largest predatory fish in Arctic waters. The socio-economic significance of Greenland shark is demonstrated by its impact on the fishing cultures in Greenland, Scandinavia and Iceland for centuries. The fundamental biology and ecological role of Greenland shark, on the other hand, is virtually unknown. Although knowledge of its life history is limited, increasing evidence indicates that the Greenland shark may unde...
Norm equivalence and composition operators between Bloch/Lipschitz spaces of the ball
Stević Stevo; Clahane Dana D
2006-01-01
For , let and denote, respectively, the -Bloch and holomorphic -Lipschitz spaces of the open unit ball in . It is known that and are equal as sets when . We prove that these spaces are additionally norm-equivalent, thus extending known results for and the polydisk. As an application, we generalize work by Madigan on the disk by investigating boundedness of the composition operator from to .
Institute of Scientific and Technical Information of China (English)
Robert F.Allen
2014-01-01
We study the bounded and the compact weighted composition operators from the Bloch space into the weighted Banach spaces of holomorphic functions on bounded homogeneous domains, with particular attention to the unit polydisk. For bounded homogeneous domains, we characterize the bounded weighted composition operators and determine the operator norm. In addition, we provide sufficient condi-tions for compactness. For the unit polydisk, we completely characterize the compact weighted composition operators, as well as provide ”computable” estimates on the operator norm.
Floquet-Bloch vs. Nicolson-Ross-Weir Extraction for Magneto-Dielectric Bragg Stacks
DEFF Research Database (Denmark)
Clausen, Niels Christian Jerichau; Arslanagic, Samel; Breinbjerg, Olav
We extract and compare the permittivity and permeability from a dielectric and a magnetodielectric Bragg stack with the Floquet-Bloch (FB) method for the infinite stack and the Nicolson-Ross- Weir (NRW) method for the finite stack. While the extracted propagation constants are identical, the wave...... impedances are different. Moreover, the NRWmethod yields magnetic effects for the dielectric Bragg stack, while the FB method gives the expected vacuum permeability, also in the bandgab....
Grating-Coupling-Based Excitation of Bloch Surface Waves for Lab-on-Fiber Nanoprobes
Scaravilli, Michele; Castaldi, Giuseppe; Cusano, Andrea; Galdi, Vincenzo
2016-01-01
In this paper, we investigate for the first time the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, we first demonstrate the possibility to exploit a grating-coupling mechanism for on-tip excitation of BSWs, and highlight the flexibility of the proposed design as well as its intrinsic robustness to unavoidable fabrication tolerances. Subsequently, with a view towards label-free chemical and biological sensing, we present an op...
Positiveness and Pauli exception principle in raw Bloch equations for quantum boxes
Bidégaray-Fesquet, Brigitte
2010-01-01
International audience The aim of this paper is to derive a raw Bloch model for the interaction of light with quantum boxes in the framework of a two-electron-species (conduction and valence) description. This requires a good understanding of the one-species case and of the treatment of level degeneracy. In contrast with some existing literature we obtain a Liouville equation which induces the positiveness and the boundedness of solutions, that are necessary for future mathematical studies...
Positiveness and Pauli exception principle in raw Bloch equations for quantum boxes
Bidégaray-Fesquet, Brigitte
2010-10-01
The aim of this paper is to derive a raw Bloch model for the interaction of light with quantum boxes in the framework of a two-electron-species (conduction and valence) description. This requires a good understanding of the one-species case and of the treatment of level degeneracy. In contrast with some existing literature, we obtain a Liouville equation which induces the positiveness and the boundedness of solutions, that are necessary for future mathematical studies involving higher order phenomena.
Positiveness and Pauli exception principle in raw Bloch equations for quantum boxes
International Nuclear Information System (INIS)
The aim of this paper is to derive a raw Bloch model for the interaction of light with quantum boxes in the framework of a two-electron-species (conduction and valence) description. This requires a good understanding of the one-species case and of the treatment of level degeneracy. In contrast with some existing literature, we obtain a Liouville equation which induces the positiveness and the boundedness of solutions, that are necessary for future mathematical studies involving higher order phenomena.
International Nuclear Information System (INIS)
We study nonlinear wave phenomena in coupled ring resonator optical waveguides in the tight coupling regime. A discrete model for the system dynamics is put forward and its steady-state nonlinear Bloch modes are derived. The switching behaviour of the transmission system is addressed numerically and the results are explained in the light of this analytical result. We also present a numerical study on the spontaneous generation of Bragg solitons from a continuous-wave input. (paper)
Explicit Solutions of the Bethe Ansatz Equations for Bloch Electrons in a Magnetic Field
Hatsugai, Yasuhiro; Kohmoto, Mahito; Wu, Yong-Shi
1994-01-01
For Bloch electrons in a magnetic field, explicit solutions are obtained at the center of the spectrum for the Bethe ansatz equations of Wiegmann and Zabrodin. When the magnetic flux per plaquette is 1 / Q with Q an odd integer, distribution of the roots of the Bethe ansatz equation is uniform except at two points on the unit circle in the complex plane. For the semiclassical limit Q→∞, the wave function is
Muthusamy RAJASEKAR; Muthusamy THANGARAJ; Thathiredypalli R. BARATHKUMAR; Jayachandran SUBBURAJ; Kaliyan MUTHAZHAGAN
2012-01-01
Lates calcarifer (Bloch 1790) is one of the major economically important cultivable fish species in India. In this study, three populations of L. calcarifer was selected to assess the genetic diversity. Of which, two wild (Mudaslodai, Muthupettai) and one captive (Mutukadu) population. The genetic diversity of three populations of this species was studied using Random Amplified Polymorphic DNA (RAPD) markers. Ten random primers were used for the assessment of their genetic diversity and const...
Derivation of Bloch equations from the time convolution less generalized master equation
International Nuclear Information System (INIS)
The generalized Bloch equations (GBE) describing the temporal evolution of a single two-level atom interacting with a classical external field of arbitrary intensity and with a thermodynamic bath are obtained from the time convolutionless generalized master equation or equivalently from the Tokuyama-Mori identity. These GBE are then used to calculate the absorption spectrum of a single two-level atom with frequency modulated by dichotomic noise with time-dependent transition probability. (author)
Zitterbewegung, Bloch Oscillations and Landau-Zener Tunneling in a Quantum Walk
Regensburger, Alois; Hinrichs, Benjamin; Onishchukov, Georgy; Schreiber, Andreas; Silberhorn, Christine; Peschel, Ulf
2011-01-01
We experimentally investigate a discrete time quantum walk in a system of coupled fiber loops and observe typical phenomena known from the wave propagation in periodic structures as ballistic spreading or an oscillation between two internal quantum states similar to Zitterbewegung (trembling motion). If a position-dependent phase gradient is applied we find localization and Bloch oscillations of the field for moderate as well as Landau-Zener tunneling for strong phase gradients.
Dynamic scattering of electron vortex beams – A Bloch wave analysis
International Nuclear Information System (INIS)
Two important applications of electron vortex beams are in electron magnetic chiral dichroism (EMCD) measurements and nanoparticle manipulation. In both cases orbital angular momentum (
Representability of Bloch states on Projector-augmented-wave (PAW) basis sets
Agapito, Luis; Ferretti, Andrea; Curtarolo, Stefano; Buongiorno Nardelli, Marco
2015-03-01
Design of small, yet `complete', localized basis sets is necessary for an efficient dual representation of Bloch states on both plane-wave and localized basis. Such simultaneous dual representation permits the development of faster more accurate (beyond DFT) electronic-structure methods for atomistic materials (e.g. the ACBN0 method.) by benefiting from algorithms (real and reciprocal space) and hardware acceleration (e.g. GPUs) used in the quantum-chemistry and solid-state communities. Finding a `complete' atomic-orbital basis (partial waves) is also a requirement in the generation of robust and transferable PAW pseudopotentials. We have employed the atomic-orbital basis from available PAW data sets, which extends through most of the periodic table, and tested the representability of Bloch states on such basis. Our results show that PAW data sets allow systematic and accurate representability of the PAW Bloch states, better than with traditional quantum-chemistry double-zeta- and double-zeta-polarized-quality basis sets.
Selective scattering between Floquet-Bloch and Volkov states in a topological insulator
Mahmood, Fahad; Chan, Ching-Kit; Alpichshev, Zhanybek; Gardner, Dillon; Lee, Young; Lee, Patrick A.; Gedik, Nuh
2016-04-01
The coherent optical manipulation of solids is emerging as a promising way to engineer novel quantum states of matter. The strong time-periodic potential of intense laser light can be used to generate hybrid photon-electron states. Interaction of light with Bloch states leads to Floquet-Bloch states, which are essential in realizing new photo-induced quantum phases. Similarly, dressing of free-electron states near the surface of a solid generates Volkov states, which are used to study nonlinear optics in atoms and semiconductors. The interaction of these two dynamic states with each other remains an open experimental problem. Here we use time- and angle-resolved photoemission spectroscopy (Tr-ARPES) to selectively study the transition between these two states on the surface of the topological insulator Bi2Se3. We find that the coupling between the two strongly depends on the electron momentum, providing a route to enhance or inhibit it. Moreover, by controlling the light polarization we can negate Volkov states to generate pure Floquet-Bloch states. This work establishes a systematic path for the coherent manipulation of solids via light-matter interaction.
Real-time protein aggregation monitoring with a Bloch surface wave-based approach
Santi, Sara; Barakat, Elsie; Descrovi, Emiliano; Neier, Reinhard; Herzig, Hans Peter
2014-05-01
The misfolding and aggregation of amyloid proteins has been associated with incurable diseases such as Alzheimer's or Parkinson's disease. In the specific case of Alzheimer's disease, recent studies have shown that cell toxicity is caused by soluble oligomeric forms of aggregates appearing in the early stages of aggregation, rather than by insoluble fibrils. Research on new strategies of diagnosis is imperative to detect the disease prior to the onset of clinical symptoms. Here, we propose the use of an optical method for protein aggregation dynamic studies using a Bloch surface wave based approach. A one dimension photonic crystal made of a periodic stack of silicon oxide and silicon nitride layers is used to excite a Bloch surface wave, which is sensitive to variation of the refractive index of an aqueous solution. The aim is to detect the early dynamic events of protein aggregation and fibrillogenesis of the amyloid-beta peptide Aβ42, which plays a central role in the onset of the Alzheimer's disease. The detection principle relies on the refractive index changes caused by the depletion of the Aβ42 monomer concentration during oligomerization and fibrillization. We demonstrate the efficacy of the Bloch surface wave approach by monitoring in real-time the first crucial steps of Aβ42 oligomerization.
Observation of Bloch oscillations in complex PT-symmetric photonic lattices
Wimmer, Martin; Miri, Mohammed-Ali; Christodoulides, Demetrios; Peschel, Ulf
2015-12-01
Light propagation in periodic environments is often associated with a number of interesting and potentially useful processes. If a crystalline optical potential is also linearly ramped, light can undergo periodic Bloch oscillations, a direct outcome of localized Wannier-Stark states and their equidistant eigenvalue spectrum. Even though these effects have been extensively explored in conservative settings, this is by no means the case in non-Hermitian photonic lattices encompassing both amplification and attenuation. Quite recently, Bloch oscillations have been predicted in parity-time-symmetric structures involving gain and loss in a balanced fashion. While in a complex bulk medium, one intuitively expects that light will typically follow the path of highest amplification, in a periodic system this behavior can be substantially altered by the underlying band structure. Here, we report the first experimental observation of Bloch oscillations in parity-time-symmetric mesh lattices. We show that these revivals exhibit unusual properties like secondary emissions and resonant restoration of PT symmetry. In addition, we present a versatile method for reconstructing the real and imaginary components of the band structure by directly monitoring the light evolution during a cycle of these oscillations.
Energy Technology Data Exchange (ETDEWEB)
Clade, P
2005-10-15
From a measurement of the recoil velocity of an atom absorbing a photon, it is possible to deduce a determination of the ratio h/m between the Planck constant and the mass of the atoms and then to deduce a value of the fine structure constant alpha. To do this measurement, we use the technique of Bloch oscillations, which allows us to transfer a large number of recoils to atoms. A velocity sensor, based on velocity selective Raman transition, enables us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 4.4 10{sup -9}, in conjunction with a careful study of systematic effects (5 10{sup -9}), has led us to a determination of alpha with an uncertainty of 6.7 10{sup -9}: {alpha}{sup -1}(Rb) = 137.03599878 (91). This uncertainty is similar to the uncertainty of the best determinations of alpha based on atom interferometry. (author)
Rabi Oscillations in Realistic Superlattice with Finite Bloch Bands
Institute of Scientific and Technical Information of China (English)
FAN Wen-Bin; ZHANG Ping; LUO Ying; ZHAO Xian-Geng
2001-01-01
We investigate the dynamical processes taking place in nanodevices by high-frequency dc-ac fields. We found that Rabi oscillations between minibands are clearly identified under theoretical resonant conditions derived by an ideal two-band superlattice model, the resonant conditions have broadened, and the amount of broadening is about four times of the Rabi oscillation frequency. We also want to elucidate the role of different mechanisms that could lead to loss of quantum coherence. Our results show how the dephasing effects of disorder of interface roughness and doping fluctuation that after some periods destroy coherent oscillations, such as Rabi oscillations,can be reduced dramatically if we apply a bias static electric field to the superlattice system. The doping fluctuation dephasing effect is much stronger than that of interface roughness in the coherent process of realistic superlattices.
Energy Technology Data Exchange (ETDEWEB)
Saenphet, S.; Thaworn, W.; Saenphet, K. [Chiang Mai University, Chiang Mai (Thailand). Faculty of Science
2009-09-15
The acidity of mine water generally makes it toxic to most organisms. The gills, kidneys and livers of Anabas testudineus Bloch fish inhabiting the acidic water (pH 2-4) of an unused lignite mine in Li District, Lamphun Province, Thailand were examined and compared to those of farmed fish. Tissue abnormalities were found in all investigated organs. Deterioration and telangiectasia of gill filaments were found. Liver tissue revealed hemorrhages, blood congestion and necrotic cells with mononuclear cell infiltration. In addition, hypertrophy of the epithelial cells of the renal tubules with reduced lumens, aneurisms of the renal tubules, and contractions of the glomeruli in the Bowman's capsule were observed. These histopathological findings suggest the acidic water in this habitat causes severe damage to the internal organs of fish and consequently alter their physiological status. Since the water in this pond is utilized by local people, these findings highlight the need for adequate water treatment.
Extraction of optical Bloch modes in a photonic-crystal waveguide
Huisman, S R; Stobbe, S; Herek, J L; Lodahl, P; Vos, W L; Pinkse, P W H
2011-01-01
We perform phase-sensitive near-field scanning optical microscopy on photonic-crystal waveguides. The observed intricate field patterns are analyzed by spatial Fourier transformations, revealing several guided TE- and TM-like modes. Using the reconstruction algorithm proposed by Ha, et al. (Opt. Lett. 34 (2009)), we decompose the measured two-dimensional field pattern in a superposition of propagating Bloch modes. This opens new possibilities to study specific modes in near-field measurements. We apply the method to study the transverse behavior of a guided TE-like mode, where the mode extends deeper in the surrounding photonic crystal when the band edge is approached.
Energy Technology Data Exchange (ETDEWEB)
Lyo, Sungkwun Kenneth; Pan, Wei; Reno, John Louis; Wendt, Joel Robert; Barton, Daniel Lee
2008-09-01
We have investigated the physics of Bloch oscillations (BO) of electrons, engineered in high mobility quantum wells patterned into lateral periodic arrays of nanostructures, i.e. two-dimensional (2D) quantum dot superlattices (QDSLs). A BO occurs when an electron moves out of the Brillouin zone (BZ) in response to a DC electric field, passing back into the BZ on the opposite side. This results in quantum oscillations of the electron--i.e., a high frequency AC current in response to a DC voltage. Thus, engineering a BO will yield continuously electrically tunable high-frequency sources (and detectors) for sensor applications, and be a physics tour-de-force. More than a decade ago, Bloch oscillation (BO) was observed in a quantum well superlattice (QWSL) in short-pulse optical experiments. However, its potential as electrically biased high frequency source and detector so far has not been realized. This is partially due to fast damping of BO in QWSLs. In this project, we have investigated the possibility of improving the stability of BO by fabricating lateral superlattices of periodic coupled nanostructures, such as metal grid, quantum (anti)dots arrays, in high quality GaAs/Al{sub x}Ga{sub 1-x}As heterostructures. In these nanostructures, the lateral quantum confinement has been shown theoretically to suppress the optical-phonon scattering, believed to be the main mechanism for fast damping of BO in QWSLs. Over the last three years, we have made great progress toward demonstrating Bloch oscillations in QDSLs. In the first two years of this project, we studied the negative differential conductance and the Bloch radiation induced edge-magnetoplasmon resonance. Recently, in collaboration with Prof. Kono's group at Rice University, we investigated the time-domain THz magneto-spectroscopy measurements in QDSLs and two-dimensional electron systems. A surprising DC electrical field induced THz phase flip was observed. More measurements are planned to investigate this
Institute of Scientific and Technical Information of China (English)
CHEN Li-Xue(陈历学); KIM Dalwoo; SONG Ying-Lin(宋瑛琳); DING Wei-Qiang(丁卫强); LI Wen-Hui(李文惠); LIU Shu-Tian(刘树田)
2004-01-01
One-dimensional photonic crystal of second-order nonlinearity is studied. Among the three waves of the parametric interaction process of down-conversion with a nondispersive medium, two gap-edge localized modes and one travelling-mode are proposed, and an exact phase matching condition is realized using the periodic condition of the Bloch phase. Numerical simulation is implemented by the slow-envelope finite difference time domain method. In the case of a pulse wave pump of amplitude half-width 5.2 × 10-13 s, an intense optical parametric pulse with half-width about 5 × 10-14 s is observed.
DEFF Research Database (Denmark)
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper;
2014-01-01
In open nanophotonic structures, the natural modes are so-called quasi-normal modes satisfying an outgoing wave boundary condition. We present a new scheme based on a modal expansion technique, a scattering matrix approach and Bloch modes of periodic structures for determining these quasi......-normal modes. As opposed to spatial discretization methods like the nite-dierence time-domain method and the nite element method, the present approach satises automatically the outgoing wave boundary condition in the propagation direction which represents a signicant advantage of our new method. The scheme...
Fornasari, Lucia; Floris, Francesco; Patrini, Maddalena; Comoretto, Davide; Marabelli, Franco
2016-05-18
An all-polymer photonic structure constituted by a distributed Bragg reflector topped with an ultrathin fluorescent polymer film has been studied. A Bloch surface wave resonance has been exploited to improve pumping efficiency. A strongly polarization and angle dependent fluorescence signal is found with respect to the light pumping beam and the emitted wavelength. Matching the most favorable condition for the pump coupling and the collection geometry, the signal obtained from the structure appears to be two orders of magnitude larger than the one of the bare emitting film. PMID:27158698
Experimental reconstruction of the Berry curvature in a topological Bloch band
Weitenberg, Christof; Flaeschner, Nick; Rem, Benno; Tarnowski, Matthias; Vogel, Dominik; Luehmann, Dirk-Soeren; Sengstock, Klaus
2016-05-01
Topological properties lie at the heart of many fascinating phenomena in solid state systems such as quantum Hall systems or Chern insulators. The topology can be captured by the distribution of Berry curvature, which describes the geometry of the eigenstates across the Brillouin zone. Employing fermionic ultracold atoms in a hexagonal optical lattice, we engineer the Berry curvature of the Bloch bands using resonant driving and measure it with full momentum resolution. Our results pave the way to explore intriguing phases of matter with interactions in topological band structures.
Sturmberg, Björn C. P.; Dossou, Kokou B.; Lawrence, Felix J.; Poulton, Christopher G.; McPhedran, Ross C.; de Sterke, C. Martijn; Botten, Lindsay C.
2016-05-01
We describe EMUstack, an open-source implementation of the Scattering Matrix Method (SMM) for solving field problems in layered media. The fields inside nanostructured layers are described in terms of Bloch modes that are found using the Finite Element Method (FEM). Direct access to these modes allows the physical intuition of thin film optics to be extended to complex structures. The combination of the SMM and the FEM makes EMUstack ideally suited for studying lossy, high-index contrast structures, which challenge conventional SMMs.
International Nuclear Information System (INIS)
We propose a photonic structure stacked sequentially by one-dimensional photonic crystals and cavities. The whole structure is composed of single-negative and double-negative materials. The optical Wannier–Stark ladder (WSL) can be obtained in a low frequency region by modulating the widths of the cavities in order. We simulate the dynamical behavior of the electromagnetic wave passing through the proposed photonic structure. Due to the dispersive characteristics of the metamaterials, a very narrow WSL can be obtained. The long-period electromagnetic Bloch oscillation is demonstrated theoretically to have a period on a microsecond time scale. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
International Nuclear Information System (INIS)
The author performed the histological analysis of the oocytes of golden (Chinese) carp, Carassius auratus gibelio (Bloch). Its habitat was radioactive-contaminated Belarusian reservoirs within Chernobyl zone. The obtained results revealed that the oocytes underwent some degenerative alterations such as irregular nucleus shape and karyolysis. That was witnessed by examination of the fish of Perstok Lake where water was characterized by the high level of radioactive contamination. It was shown that the alterations were connected with the high level of natural habitat contamination. These alterations were also caused by the high content of radionuclides in fish tissuies and organs
Modified-Bloch-equation description of EPR transient nutations and free induction decay in solids
International Nuclear Information System (INIS)
Based on the experimental work by Boscaino et al on the EPR transient nutations (TNs) and free induction decay (FID) in solids, we propose the modified Bloch equations (MBEs). In addition to the Tomita expression for power-dependent parameter T2u, we give an original phenomenological expression for power-dependent parameter T2v and tuning Δ. Both analytical (in the form of a Torrey solution with these parameters) and numerical solutions of MBE are obtained for TN and for different FID regimes with very good agreement between theory and experiment. We also discuss the meaning and role of the instantaneous diffusion mechanism in the transient pulse experiments. (author)
Bloch-type domain walls in rhombohedral BaTiO.sub.3./sub..
Czech Academy of Sciences Publication Activity Database
Taherinejad, M.; Vanderbilt, D.; Márton, Pavel; Stepkova, Vilgelmina; Hlinka, Jiří
2012-01-01
Roč. 86, č. 15 (2012), "155138-1"-"155138-8". ISSN 1098-0121 R&D Projects: GA ČR GA202/09/0430; GA ČR GAP204/10/0616 Institutional research plan: CEZ:AV0Z10100520 Keywords : domain walls * Bloch domain walls * rhombohedral phase * phase-field approach * first-principles approach Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012 http://prb.aps.org/abstract/PRB/v86/i15/e155138
Explicit Solutions of the Bethe Ansatz Equations for Bloch Electrons in a Magnetic Field
Hatsugai, Yasuhiro; Kohmoto, Mahito; Wu, Yong-Shi
1994-01-01
For Bloch electrons in a magnetic field, explicit solutions are obtained at the center of the spectrum for the Bethe ansatz equations recently proposed by Wiegmann and Zabrodin. When the magnetic flux per plaquette is $1/Q$ where $Q$ is an odd integer, distribution of the roots is uniform on the unit circle in the complex plane. For the semi-classical limit, $ Q\\rightarrow\\infty$, the wavefunction obeys the power low and is given by $|\\psi(x)|^2=(2/ \\sin \\pi x)$ which is critical and unnormal...
Quantum Group, Bethe Ansatz and Bloch Electrons in a Magnetic Field
Hatsugai, Y.; Kohmoto, M.; Wu, Y.-S.
1995-01-01
The wave functions for two dimensional Bloch electrons in a uniform magnetic field at the mid-band points are studied with the help of the algebraic structure of the quantum group $U_q(sl_2)$. A linear combination of its generators gives the Hamiltonian. We obtain analytical and numerical solutions for the wave functions by solving the Bethe Ansatz equations, proposed by Wiegmann and Zabrodin on the basis of above observation. The semi-classical case with the flux per plaquette $\\phi=1/Q$ is ...
UGROŽENE VRSTE RIBA U SVIJETU: Mystus vittatus (Bloch, 1794) (Siluriformes: Bagridae)
Hossain, Yeamin
2014-01-01
Autohtona vrsta, Mystus vittatus (Bloch, 1794), pripadnik porodice Bagridae, široke je distribucije u azijskim zemljama, uključujući Bangladeš, Indiju, Pakistan, Šri Lanku, Nepal i Mianmar. Međutim, prirodne populacije ozbiljno opadaju zbog visokog ribolovnog pritiska, gubitka staništa, zagađenja, prirodnih katastrofa, sanacije močvara i prekomjernog poplavnog zamuljivanja pa se stoga nalazi se u kategoriji osjetljive vrste. U članku se predlažu mjere za očuvanje ostatka izolirane populacije ...
Institute of Scientific and Technical Information of China (English)
SUN Hui-Yuan; HU Yun-Zhi; LIU Li-Hu
2009-01-01
The diameters of the ordinary hard bubbles (OHBs) and soft bubbles in epitaxial garnet films are measured under the microscope at various temperatures. It is found that the bubble diameters of OHBs increase with temperature, and it is concluded that the equilibrium separation between two neighbouring vertical Bloch lines (VBLs) Seq is widened with increasing temperature. At the same time, the results can be understood simply as that there are more VBLs in the domain walls of the first dumbbell domains (IDs) than those in walls of OH Bs at the same temperature.
Weighted Composition Operators from α-Bloch Spaces to H∞%α-Bloch空间到H∞的加权复合算子
Institute of Scientific and Technical Information of China (English)
唐笑敏
2007-01-01
The article not only presents the boundedness and compactness of the weighted composition operator from α-Bloch spaces(or little α-Bloch spaces) to H∞, but also gives some estimates for the norm of the weighted composition operator.
International Nuclear Information System (INIS)
Small-angle scattering of neutrons allows the determination of the orientation of Bloch walls in the interior of bulk single crystals. The zigzag angle psi=280 of the 900 Bloch wall and its field dependence are measured. We also observe walls or wall pieces with psi=00. With 1800 walls we measure zigzag angles of psi approximately equal to 300. (orig.)
Wieser, R
2016-10-01
The derivation of the time dependent Schrödinger equation with transversal and longitudinal relaxation, as the quantum mechanical analog of the classical Landau-Lifshitz-Bloch equation, has been described. Starting from the classical Landau-Lifshitz-Bloch equation the transition to quantum mechanics has been performed and the corresponding von-Neumann equation deduced. In a second step the time Schrödinger equation has been derived. Analytical proofs and computer simulations show the correctness and applicability of the derived Schrödinger equation. PMID:27494599
Tscherbul, Timur V.; Brumer, Paul
2015-03-01
We present an efficient theoretical method for calculating the time evolution of the density matrix of a multilevel quantum system weakly interacting with incoherent light. The method combines the Bloch-Redfield theory with a partial secular approximation for one-photon coherences, resulting in a master equation that explicitly exposes the reliance on transition rates and the angles between transition dipole moments in the energy basis. The partial secular Bloch-Redfield master equation allows an unambiguous distinction between the regimes of quantum coherent vs. incoherent energy transfer under incoherent light illumination. The fully incoherent regime is characterized by orthogonal transition dipole moments in the energy basis, leading to a dynamical evolution governed by a coherence-free Pauli-type master equation. The coherent regime requires non-orthogonal transition dipole moments in the energy basis and leads to the generation of noise-induced quantum coherences and population-to-coherence couplings. As a first application, we consider the dynamics of excited state coherences arising under incoherent light excitation from a single ground state and observe population-to-coherence transfer and the formation of non-equilibrium quasisteady states in the regime of small excited state splitting. Analytical expressions derived earlier for the V-type system [T. V. Tscherbul and P. Brumer, Phys. Rev. Lett. 113, 113601 (2014)] are found to provide a nearly quantitative description of multilevel excited-state populations and coherences in both the small- and large-molecule limits.
Raman fingerprints on the Bloch sphere of a spinor Bose-Einstein condensate
Schultz, Justin T; Murphree, Joseph D; Jayaseelan, Maitreyi; Bigelow, Nicholas P
2016-01-01
We explore the geometric interpretation of a diabatic, two-photon Raman process as a rotation on the Bloch sphere for a pseudo-spin-1/2 system. The spin state of a spin-1/2 quantum system can be described by a point on the surface of the Bloch sphere, and its evolution during a Raman pulse is a trajectory on the sphere determined by properties of the optical beams: the pulse area, the relative intensities and phases, and the relative frequencies. We experimentally demonstrate key features of this model with a $^{87}$Rb spinor Bose-Einstein condensate, which allows us to examine spatially dependent signatures of the Raman beams. The two-photon detuning allows us to precisely control the spin density and imprinted relative phase profiles, as we show with a coreless vortex. With this comprehensive understanding and intuitive geometric interpretation, we use the Raman process to create and tailor as well as study and characterize exotic topological spin textures in spinor BECs.
Dai, Jin; Niemi, Antti J.; He, Jianfeng; Sieradzan, Adam; Ilieva, Nevena
2016-03-01
We inquire how structure emerges during the process of protein folding. For this we scrutinize collective many-atom motions during all-atom molecular dynamics simulations. We introduce, develop, and employ various topological techniques, in combination with analytic tools that we deduce from the concept of integrable models and structure of discrete nonlinear Schrödinger equation. The example we consider is an α -helical subunit of the HIV envelope glycoprotein gp41. The helical structure is stable when the subunit is part of the biological oligomer. But in isolation, the helix becomes unstable, and the monomer starts deforming. We follow the process computationally. We interpret the evolving structure both in terms of a backbone based Heisenberg spin chain and in terms of a side chain based XY spin chain. We find that in both cases the formation of protein supersecondary structure is akin the formation of a topological Bloch domain wall along a spin chain. During the process we identify three individual Bloch walls and we show that each of them can be modelled with a precision of tenths to several angstroms in terms of a soliton solution to a discrete nonlinear Schrödinger equation.
Energy Technology Data Exchange (ETDEWEB)
Tscherbul, Timur V., E-mail: ttscherb@chem.utoronto.ca; Brumer, Paul [Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)
2015-03-14
We present an efficient theoretical method for calculating the time evolution of the density matrix of a multilevel quantum system weakly interacting with incoherent light. The method combines the Bloch-Redfield theory with a partial secular approximation for one-photon coherences, resulting in a master equation that explicitly exposes the reliance on transition rates and the angles between transition dipole moments in the energy basis. The partial secular Bloch-Redfield master equation allows an unambiguous distinction between the regimes of quantum coherent vs. incoherent energy transfer under incoherent light illumination. The fully incoherent regime is characterized by orthogonal transition dipole moments in the energy basis, leading to a dynamical evolution governed by a coherence-free Pauli-type master equation. The coherent regime requires non-orthogonal transition dipole moments in the energy basis and leads to the generation of noise-induced quantum coherences and population-to-coherence couplings. As a first application, we consider the dynamics of excited state coherences arising under incoherent light excitation from a single ground state and observe population-to-coherence transfer and the formation of non-equilibrium quasisteady states in the regime of small excited state splitting. Analytical expressions derived earlier for the V-type system [T. V. Tscherbul and P. Brumer, Phys. Rev. Lett. 113, 113601 (2014)] are found to provide a nearly quantitative description of multilevel excited-state populations and coherences in both the small- and large-molecule limits.
Creating full-Bloch Bose–Einstein condensates with Raman q-plates
Schultz, Justin T.; Hansen, Azure; Murphree, Joseph D.; Jayaseelan, Maitreyi; Bigelow, Nicholas P.
2016-06-01
A coherent two-photon optical Raman interaction in a pseudo-spin-1/2 Bose–Einstein condensate (BEC) serves as a q-plate for atoms, converting spin to orbital angular momentum. This Raman q-plate has a singular pattern in its polarization distribution in analogy to the singular birefringent q-plates used in singular optics. The vortex winding direction and magnitude as well as the final spin state of the BEC depend on the initial spin state and the topology of the optical Raman q-plate beams. Drawing on the mathematical and geometric foundations of singular optics, we derive the equivalent Jones matrix for this Raman q-plate and use it to create and characterize atomic spin singularities in the BEC that are analogous to optical C-point singularities in polarization. By tuning the optical Raman parameters, we can generate a coreless vortex spin texture which contains every possible superposition in a two-state system. We identify this spin texture as a full-Bloch BEC since every point on the Bloch sphere is represented at some point in the cross section of the atomic cloud. This spin–orbit interaction and the spin textures it generates may allow for the observation of interesting geometric phases in matter waves and lead to schemes for topological quantum computation with spinor BECs.
Wannier-Bloch approach to localization in high harmonics generation in solids
Osika, Edyta N; Ortmann, Lisa; Suárez, Noslen; Pérez-Hernández, Jose Antonio; Szafran, Bartłomiej; Ciappina, Marcelo F; Sols, Fernando; Landsman, Alexandra S; Lewenstein, Maciej
2016-01-01
Emission of high-order harmonics from solids provides a new avenue in attosecond science. On one hand, it allows to investigate fundamental processes of the non-linear response of electrons driven by a strong laser pulse in a periodic crystal lattice. On the other hand, it opens new paths toward efficient attosecond pulse generation, novel imaging of electronic wave functions, and enhancement of high-order harmonic generation (HHG) intensity. A key feature of HHG in a solid (as compared to the well-understood phenomena of HHG in an atomic gas) is the delocalization of the process, whereby an electron ionized from one site in the periodic lattice may recombine with any other. Here, we develop an analytic model, based on the localized Wannier wave functions in the valence band and delocalized Bloch functions in the conduction band. This Wannier-Bloch approach assesses the contributions of individual lattice sites to the HHG process, and hence addresses precisely the question of localization of harmonic emission...
Deza, Michel Marie
2016-01-01
This 4th edition of the leading reference volume on distance metrics is characterized by updated and rewritten sections on some items suggested by experts and readers, as well a general streamlining of content and the addition of essential new topics. Though the structure remains unchanged, the new edition also explores recent advances in the use of distances and metrics for e.g. generalized distances, probability theory, graph theory, coding theory, data analysis. New topics in the purely mathematical sections include e.g. the Vitanyi multiset-metric, algebraic point-conic distance, triangular ratio metric, Rossi-Hamming metric, Taneja distance, spectral semimetric between graphs, channel metrization, and Maryland bridge distance. The multidisciplinary sections have also been supplemented with new topics, including: dynamic time wrapping distance, memory distance, allometry, atmospheric depth, elliptic orbit distance, VLBI distance measurements, the astronomical system of units, and walkability distance. Lea...
Bazeia, D
2004-01-01
We investigate a system described by two real scalar fields coupled with gravity in (4, 1) dimensions in warped spacetime involving one extra dimension. The results show that the parameter which controls the way the two scalar fields interact induces the appearence of thick brane which engenders internal structure, driving the energy density to localize inside the brane in a very specific way.
Distance education on geograpgy
Bargailienė, Lina
2005-01-01
Topic: distance education on geography. The target of this master writing is to research the usage of distance education courses to teach geography. This title gives overview on history, popularity and the spread of learning on distance education in Lithuania and the World. It analyses learning procedures and techniques, overviews existing education courses, evaluates distance education software and web services, gives overview of the distance learning course development sta...
Dambov, Risto; Karanakova Stefanovska, Radmila; Dambov, Ilija
2015-01-01
In blasting performance for any purpose and in any location to implement these safeguards is necessary first to determine (calculated) safety distances in terms of the effect of the explosion from some explosive quantity. Calculation of distance safety in blasting performance are refers to: calculation of safety distances from the influence of air - shock waves, calculation of safety distances (zones) of spraying pieces (fragments action) and calculation of safety distances in action of seis...
Deza, Michel Marie
2014-01-01
This updated and revised third edition of the leading reference volume on distance metrics includes new items from very active research areas in the use of distances and metrics such as geometry, graph theory, probability theory and analysis. Among the new topics included are, for example, polyhedral metric space, nearness matrix problems, distances between belief assignments, distance-related animal settings, diamond-cutting distances, natural units of length, Heidegger’s de-severance distance, and brain distances. The publication of this volume coincides with intensifying research efforts into metric spaces and especially distance design for applications. Accurate metrics have become a crucial goal in computational biology, image analysis, speech recognition and information retrieval. Leaving aside the practical questions that arise during the selection of a ‘good’ distance function, this work focuses on providing the research community with an invaluable comprehensive listing of the main available di...
Hardware Euclidean Distance Transform Implementation
Institute of Scientific and Technical Information of China (English)
XIE Ying-hua; ZENG Pei-feng; TANG Li-ping
2004-01-01
Based on an efficient algorithm of Euclidean distance transform for binary images, a circuit of O(N2) size is proposed. With in-place calculation, both the intermediate data storing and the result output use the same memory with the input data. This reduces the amount of memory largely. By replacing multipliers with counters, comparators, and adders, the circuit size is further reduced and its calculation speed is improved also.
Multiflavor bosonic Hubbard models in the first excited Bloch band of an optical lattice
International Nuclear Information System (INIS)
We propose that by exciting ultracold atoms from the zeroth to the first Bloch band in an optical lattice, multiflavor bosonic Hubbard Hamiltonians can be realized in a different way. In these systems, each flavor hops in a separate direction and on-site exchange terms allow pairwise conversion between different flavors. Using band-structure calculations, we determine the parameters entering these Hamiltonians and derive the mean-field ground-state phase diagram for two effective Hamiltonians (two dimensional, two flavors, and three dimensional, three flavors). Further, we estimate the stability of atoms in the first band using second-order perturbation theory and find lifetimes that can be considerably (10-100 times) longer than the relevant time scale associated with intersite hopping dynamics, suggesting that quasiequilibrium can be achieved in these metastable states
Effects of gamma radiations on certain tissues of heteropneustes fossils bloch
International Nuclear Information System (INIS)
In the present investigation effect of gamma radiation on certain tissues (kidney, stomach and gills) of Heteropneustes fossilis Bloch, an Indian Cat fish, were studied. The fish were irradiated with 10 Gy of gamma radiations at the dose rate of 1.60 Gy/minute from a 60Co source. Five fish were autopsied at each post-irradiation time of 1,2,3,7,15 and 30 days. Radiation induced histopathology was observed in all the tissues studied. The radio lesions appeared on day-1 after exposure which became exaggerated on day-2 and 3. Signs of recovery were noticed on day-7 which progressed on day-15 and normal histology was observed on day-30. (author). 18 refs
Bloch oscillations of ultracold atoms and measurement of the fine structure constant
International Nuclear Information System (INIS)
From a measurement of the recoil velocity of an atom absorbing a photon, it is possible to deduce a determination of the ratio h/m between the Planck constant and the mass of the atoms and then to deduce a value of the fine structure constant alpha. To do this measurement, we use the technique of Bloch oscillations, which allows us to transfer a large number of recoils to atoms. A velocity sensor, based on velocity selective Raman transition, enables us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 4.4 10-9, in conjunction with a careful study of systematic effects (5 10-9), has led us to a determination of alpha with an uncertainty of 6.7 10-9: α-1(Rb) = 137.03599878 (91). This uncertainty is similar to the uncertainty of the best determinations of alpha based on atom interferometry. (author)
Geometric optics of Bloch waves in a chiral and dissipative medium
International Nuclear Information System (INIS)
We present a geometric optics theory for the transport of quantum particles (or classical waves) in a chiral and dissipative periodic crystal subject to slowly varying perturbations in space and time. Taking account of some properties of particles and media neglected in previous theory, we find important additional terms in the equations of motion of particles. The (energy) current density field, which traces the geometric optics rays, is not only governed by the Bloch band energy dispersion but also involves there additional fields. These are the angular momentum of the particle, the dissipation dipole density, and various geometric gauge fields in the extended phase space spanned by space time and its reciprocal, momentum, and frequency. For simplicity, the theory is presented using light propagation in photonic crystals.
Electroweak corrections and Bloch-Nordsieck violations in 2-to-2 processes at the LHC
Stirling, W. J.; Vryonidou, E.
2013-04-01
We consider the effect of next-to-leading order (NLO) electroweak corrections to Standard Model 2 → 2 processes, taking into account the potentially large double logarithms originating from both real and virtual corrections. A study of the leading Sudakov logarithms is presented and Bloch-Nordsieck (BN) violations are discussed for processes at the CERN Large Hadron Collider. In particular, we focus on the processes Z/γ+jet and also the ratio of Z to γ production. This ratio is known to be insensitive to NLO QCD corrections but this is not expected to be the case for the electroweak corrections. We also comment on the effect of electroweak corrections and the presence of BN violation for QCD processes, in particular dijet production, and also for purely electroweak processes such as W + H and W + Z associated production.
Electroweak corrections and Bloch-Nordsieck violations in 2-to-2 processes at the LHC
Stirling, W J
2013-01-01
We consider the effect of next-to-leading order (NLO) electroweak corrections to Standard Model 2-to-2 processes, taking into account the potentially large double logarithms originating from both real and virtual corrections. A study of the leading Sudakov logarithms is presented and Bloch-Nordsieck (BN) violations are discussed for processes at the CERN Large Hadron Collider. In particular, we focus on the processes Z/photon+jet and also the ratio of Z to photon production. This ratio is known to be insensitive to NLO QCD corrections but this is not expected to be the case for the electroweak corrections. We also comment on the effect of electroweak corrections and the presence of BN violation for QCD processes, in particular dijet production, and also for purely electroweak processes such as W + H and W + Z associated production.
A note on the Königs domain of compact composition operators on the Bloch space
Directory of Open Access Journals (Sweden)
Jones Matthew
2011-01-01
Full Text Available Abstract Let be the unit disk in the complex plane. We define to be the little Bloch space of functions f analytic in which satisfy lim|z|→1 (1 - |z|2|f'(z| = 0. If is analytic then the composition operator Cφ : f ↦ f ∘ φ is a continuous operator that maps into itself. In this paper, we show that the compactness of Cφ , as an operator on , can be modelled geometrically by its principal eigenfunction. In particular, under certain necessary conditions, we relate the compactness of Cφ to the geometry of , where σ satisfies Schöder's functional equation σ ∘ φ = φ'(0σ. 2000 Mathematics Subject Classification: Primary 30D05; 47B33 Secondary 30D45.
Measuring the fine structure constant with Bragg diffraction and Bloch oscillations
Yu, Chenghui; Estey, Brian; Parker, Richard; Dudley, Jordan; Müller, Holger
2016-05-01
We have demonstrated a new scheme for atom interferometry based on large-momentum-transfer Bragg beam splitters and Bloch oscillations. In this new scheme, we have achieved a resolution of δα / α =0.25ppb in the fine structure constant measurement, which gives up to 4.4 million radians of phase difference between freely evolving matter waves. We have suppressed many systematic effects known in most atom interferometers with Raman beam splitters such as light shift, Zeeman effect shift as well as vibration. We have also simulated multi-atom Bragg diffraction to understand sub-ppb systematic effects, and implemented spatial filtering to further suppress systematic effects. We present our recent progress toward a measurement of the fine structure constant, which will provide a stringent test of the standard model of particle physics.
Quasiclassical analysis of Bloch oscillations in non-Hermitian tight-binding lattices
Graefe, E M; Rush, A
2016-01-01
Many features of Bloch oscillations in one-dimensional quantum lattices with a static force can be described by quasiclassical considerations for example by means of the acceleration theorem, at least for Hermitian systems. Here the quasiclassical approach is extended to non-Hermitian lattices, which are of increasing interest. The analysis is based on a generalised non-Hermitian phase space dynamics developed recently. Applications to a single-band tight-binding system demonstrate that many features of the quantum dynamics can be understood from this classical description qualitatively and even quantitatively. Two non-Hermitian and $PT$-symmetric examples are studied, a Hatano-Nelson lattice with real coupling constants and a system with purely imaginary couplings, both for initially localised states in space or in momentum. It is shown that the time-evolution of the norm of the wave packet and the expectation values of position and momentum can be described in a classical picture.
Bloch waves in an arbitrary two-dimensional lattice of subwavelength Dirichlet scatterers
Schnitzer, Ory
2016-01-01
We study waves governed by the planar Helmholtz equation, propagating in an infinite lattice of subwavelength Dirichlet scatterers, the periodicity being comparable to the wavelength. Applying the method of matched asymptotic expansions, the scatterers are effectively replaced by asymptotic point constraints. The resulting coarse-grained Bloch-wave dispersion problem is solved by a generalised Fourier series, whose singular asymptotics in the vicinities of scatterers yield the dispersion relation governing modes that are strongly perturbed from plane-wave solutions existing in the absence of the scatterers; there are also empty-lattice waves that are only weakly perturbed. Characterising the latter is useful in interpreting and potentially designing the dispersion diagrams of such lattices. The method presented, that simplifies and expands on Krynkin & McIver [Waves Random Complex, 19 347 2009], could be applied in the future to study more sophisticated designs entailing resonant subwavelength elements di...
Sub-cycle control of terahertz high-harmonic generation by dynamical Bloch oscillations
Schubert, O; Langer, F; Urbanek, B; Lange, C; Huttner, U; Golde, D; Meier, T; Kira, M; Koch, S W; Huber, R
2016-01-01
Ultrafast charge transport in strongly biased semiconductors is at the heart of highspeed electronics, electro-optics, and fundamental solid-state physics. Intense light pulses in the terahertz (THz) spectral range have opened fascinating vistas: Since THz photon energies are far below typical electronic interband resonances, a stable electromagnetic waveform may serve as a precisely adjustable bias. Novel quantum phenomena have been anticipated for THz amplitudes reaching atomic field strengths. We exploit controlled THz waveforms with peak fields of 72 MV/cm to drive coherent interband polarization combined with dynamical Bloch oscillations in semiconducting gallium selenide. These dynamics entail the emission of phase-stable high-harmonic transients, covering the entire THz-to-visible spectral domain between 0.1 and 675 THz. Quantum interference of different ionization paths of accelerated charge carriers is controlled via the waveform of the driving field and explained by a quantum theory of inter- and in...
A Bloch-Torrey Equation for Diffusion in a Deforming Media
International Nuclear Information System (INIS)
Diffusion Tensor Magnetic Resonance Imaging (DTMRI)technique enables the measurement of diffusion parameters and therefore, informs on the structure of the biological tissue. This technique is applied with success to the static organs such as brain. However, the diffusion measurement on the dynamically deformable organs such as the in-vivo heart is a complex problem that has however a great potential in the measurement of cardiac health. In order to understand the behavior of the Magnetic Resonance (MR)signal in a deforming media, the Bloch-Torrey equation that leads the MR behavior is expressed in general curvilinear coordinates. These coordinates enable to follow the heart geometry and deformations through time. The equation is finally discredited and presented in a numerical formulation using implicit methods, in order to get a stable scheme that can be applied to any smooth deformations. Diffusion process enables the link between the macroscopic behavior of molecules and the microscopic structure in which they evolve. The measurement of diffusion in biological tissues is therefore of major importance in understanding the complex underlying structure that cannot be studied directly. The Diffusion Tensor Magnetic Resonance Imaging(DTMRI) technique enables the measurement of diffusion parameters and therefore provides information on the structure of the biological tissue. This technique has been applied with success to static organs such as the brain. However, diffusion measurement of dynamically deformable organs such as the in-vivo heart remains a complex problem, which holds great potential in determining cardiac health. In order to understand the behavior of the magnetic resonance (MR) signal in a deforming media, the Bloch-Torrey equation that defines the MR behavior is expressed in general curvilinear coordinates. These coordinates enable us to follow the heart geometry and deformations through time. The equation is finally discredited and presented in a
Directory of Open Access Journals (Sweden)
Claudiu Alexandru Baciu
2015-12-01
Full Text Available In our researches we have determined the variation of certain physiological indexes, such as the oxygen consume, the breathing rhythm, the glycaemia and the number of red blood cells under the action of Coragen insecticide on Carassius auratus gibelio Bloch. Under the action of Coragen, we have registered significant changes in the oxygen consume, the breathing rhythm, the number of red blood cells and glycemia at the Carassius auratus gibelio Bloch items, considered as answers to the stress provoked by emissions. The highest variations of the physiological indexes, from the perspective of the percentage, were noticed at the glycemia, which at the mark was 28 mg/dl, and in the treated sample, with 0.1 ml/l Coragen is 42 mg/dl, representing a 50% growth and at the breathing rhythm in 24 hours, where values significantly decreased with 41.18% at the concentration of 0.07 ml/l and with 39.33% at the concentrations of 0.05 and 0.1 ml/l Coragen. The slightest variations of the physiological indexes, from the perspective of percentage, were noticed at the oxygen consumption, which, at the mark is of 55.302 ml oxygen/kg/hour, and for the treated sample, with 0.1 ml/l Coragen is 34.81 ml oxygen/kg/hour, representing a decrease of 37.06% in 24 hours and the number of red blood cells, where the values have significantly decrease with 9.58%, 13.48%, respectively 18.44% for the concentrations of 0.05, 0.07 and 0.1 ml/l Coragen.
A Bloch-Torrey Equation for Diffusion in a Deforming Media
Energy Technology Data Exchange (ETDEWEB)
Rohmer, Damien; Gullberg, Grant T.
2006-12-29
Diffusion Tensor Magnetic Resonance Imaging (DTMRI)technique enables the measurement of diffusion parameters and therefore,informs on the structure of the biological tissue. This technique isapplied with success to the static organs such as brain. However, thediffusion measurement on the dynamically deformable organs such as thein-vivo heart is a complex problem that has however a great potential inthe measurement of cardiac health. In order to understand the behavior ofthe Magnetic Resonance (MR)signal in a deforming media, the Bloch-Torreyequation that leads the MR behavior is expressed in general curvilinearcoordinates. These coordinates enable to follow the heart geometry anddeformations through time. The equation is finally discretized andpresented in a numerical formulation using implicit methods, in order toget a stable scheme that can be applied to any smooth deformations.Diffusion process enables the link between the macroscopic behavior ofmolecules and themicroscopic structure in which they evolve. Themeasurement of diffusion in biological tissues is therefore of majorimportance in understanding the complex underlying structure that cannotbe studied directly. The Diffusion Tensor Magnetic ResonanceImaging(DTMRI) technique enables the measurement of diffusion parametersand therefore provides information on the structure of the biologicaltissue. This technique has been applied with success to static organssuch as the brain. However, diffusion measurement of dynamicallydeformable organs such as the in-vivo heart remains a complex problem,which holds great potential in determining cardiac health. In order tounderstand the behavior of the magnetic resonance (MR) signal in adeforming media, the Bloch-Torrey equation that defines the MR behavioris expressed in general curvilinear coordinates. These coordinates enableus to follow the heart geometry and deformations through time. Theequation is finally discretized and presented in a numerical formulationusing
Has Distance Learning Become More Flexible? Reflections of a Distance Learning Student
Thomas, Theda
2012-01-01
This paper provides insight into the way in which distance learning had changed over the past 30 years from the perspective of the author as a distance learning student. The question is then asked as to whether current practice is reducing flexibility for distance learning students? The paper starts with a discussion of flexible learning and the…
Székely, Gábor J.; Rizzo, Maria L.
2009-01-01
Distance correlation is a new class of multivariate dependence coefficients applicable to random vectors of arbitrary and not necessarily equal dimension. Distance covariance and distance correlation are analogous to product-moment covariance and correlation, but generalize and extend these classical bivariate measures of dependence. Distance correlation characterizes independence: it is zero if and only if the random vectors are independent. The notion of covariance with respect to a stochas...
Long working distance interference microscope
Sinclair, Michael B.; DeBoer, Maarten P.; Smith, Norman F.
2004-04-13
Disclosed is a long working distance interference microscope suitable for three-dimensional imaging and metrology of MEMS devices and test structures on a standard microelectronics probe station. The long working distance of 10-30 mm allows standard probes or probe cards to be used. This enables nanometer-scale 3-D height profiles of MEMS test structures to be acquired across an entire wafer. A well-matched pair of reference/sample objectives is not required, significantly reducing the cost of this microscope, as compared to a Linnik microinterferometer.
A generalized evidence distance
Institute of Scientific and Technical Information of China (English)
Hongming Mo; Xi Lu; Yong Deng
2016-01-01
How to efficiently measure the distance between two basic probability assignments (BPAs) is an open issue. In this paper, a new method to measure the distance between two BPAs is proposed, based on two existing measures of evidence distance. The new proposed method is comprehen-sive and generalized. Numerical examples are used to ilus-trate the effectiveness of the proposed method.
Waters, John K.
2012-01-01
Whoever said "Distance education begins in the 10th row" was taking a jab at the comatose kids at the back of his classroom, but the comment also taps into the old image of distance learners as disengaged themselves. That was then. Today, distance-learning programs are booming, in part due to demographic realities but also because recent advances…
Pertel, Michael J.
1992-01-01
A table of useful summation formulae are derived, together with a Mathematica package for producing them. The distance distribution in mesh routing networks is derived. The mean and variance of the distance distribution are computed. A program for computing the distance distribution of any mesh is presented.
DISTANCE-BASED UPDATE STRATEGY IN LDCQ
Institute of Scientific and Technical Information of China (English)
Dong Yi; Edward Chan; Huang Zailu
2004-01-01
A new update strategy, distance-based update strategy, is presented in Location Dependent Continuous Query (LDCQ) under error limitation. There are different possibilities to intersect when the distances between moving objects and the querying boundary are different.Therefore, moving objects have different influences to the query result. We set different deviation limits for different moving objects according to distances. A great number of unnecessary updates are reduced and the payload of the system is relieved.
DEFF Research Database (Denmark)
Larsen, Gunvor Riber
holiday could contribute to an understanding of how it is possible to change tourism travel behaviour towards becoming more sustainable. How tourists 'consume distance' is discussed, from the practical level of actually driving the car or sitting in the air plane, to the symbolic consumption of distance......The environmental impact of tourism mobility is linked to the distances travelled in order to reach a holiday destination, and with tourists travelling more and further than previously, an understanding of how the tourists view the distance they travel across becomes relevant. Based on interviews...... with Danish tourists about their holiday mobility and desires, the concept of 'consumption of distance' is developed, a concept which explores how tourists think about and engage with the distance they transcend when travelling on holiday. Consumption of distance is to be understood as a concept that...
Interface Simulation Distances
Directory of Open Access Journals (Sweden)
Pavol Černý
2012-10-01
Full Text Available The classical (boolean notion of refinement for behavioral interfaces of system components is the alternating refinement preorder. In this paper, we define a distance for interfaces, called interface simulation distance. It makes the alternating refinement preorder quantitative by, intuitively, tolerating errors (while counting them in the alternating simulation game. We show that the interface simulation distance satisfies the triangle inequality, that the distance between two interfaces does not increase under parallel composition with a third interface, and that the distance between two interfaces can be bounded from above and below by distances between abstractions of the two interfaces. We illustrate the framework, and the properties of the distances under composition of interfaces, with two case studies.
Luciano Neves dos Santos; Alejandra Filippo Gonzalez; Francisco Gerson de Araújo
2001-01-01
The diet of Cichla monoculus (Bloch & Schneider, 1801) in Lajes's Reservoir, a major impoundment in Rio de Janeiro State, Brazil, was assessed, from fishes collected in 1994,1996 and 1999/2000. Gut contents in individuals was analyzed by the index of relative importance (IRI) which deals with numerical, gravimetrical and frequency of occurrence. Cichla monoculus showed a strong piscivorous habits feeding on Cichlidae, Characidae and Pimelodidae, in decreasing order of importance, with a remar...
International Nuclear Information System (INIS)
In this paper, a generalized variable-coefficient Hirota–Maxwell–Bloch system is investigated, which can describe the propagation of optical solitons in an erbium-doped optical fiber. Higher-step generalized Darboux transformation and rogue-wave solutions are obtained. Rogue-wave interaction is analyzed as follows: (1) Variable coefficients in the system affect the shape, background and number of the wave crests and troughs of the first-step rogue waves for the modulus of the normalized slowly varying amplitude of the complex pulse envelope, modulus of the measure of the polarization of the resonant medium and extant population inversion; (2) Variable coefficients in the system affect the shape, background and number of the wave crests and troughs of the second-step rogue-wave interaction. Those phenomena can not be attained through the existing Hirota–Maxwell–Bloch system
Institute of Scientific and Technical Information of China (English)
Zhang Bing-Zhi; Cui Hu; Li Xiang-Heng; She Wei-Long
2009-01-01
We theoretically study the beam dynamical hehaviour in a modulated optical lattice with a quadratic potential in a photovoltaic photorefractive crystal. We find that two different Bloch oscillation patterns appear for the excitation of both broad and narrow light beams. One kind of optical Landau-Zener tunnelling also appears upon the Bloch oscillation and can be controlled by adjusting the parameter of the optical lattice. Unlike the case of linear potential, the energy radiation due to Landau-Zener tunnelling can be confined in modulated lattices of this kind. For high input intensity levels, the Landau-Zener tunnelling is suppressed by the photovoltaic photorefractive nonlinearity and a symmetry breaking of beam propagation from the modulational instability appears.
Distance Education for People with Visual Impairments
Liakou, Maria; Manousou, Evaggelia
2015-01-01
This paper studies the standards of higher Distance Education, focusing on the Hellenic Open University, for people who have visual impairments, so that it becomes fully accessible and thus helps reduce social exclusion. Specifically, it aims to study the operational context of Distance Education, the possibilities that modern technology provides…
Directory of Open Access Journals (Sweden)
B. Prasanna Venkatesh
2015-12-01
Full Text Available In this paper we give a new description, in terms of optomechanics, of previous work on the problem of an atomic Bose–Einstein condensate interacting with the optical lattice inside a laser-pumped optical cavity and subject to a bias force, such as gravity. An atomic wave packet in a tilted lattice undergoes Bloch oscillations; in a high-finesse optical cavity the backaction of the atoms on the light leads to a time-dependent modulation of the intracavity lattice depth at the Bloch frequency which can in turn transport the atoms up or down the lattice. In the optomechanical picture, the transport dynamics can be interpreted as a manifestation of dynamical backaction-induced sideband damping/amplification of the Bloch oscillator. Depending on the sign of the pump-cavity detuning, atoms are transported either with or against the bias force accompanied by an up- or down-conversion of the frequency of the pump laser light. We also evaluate the prospects for using the optomechanical Bloch oscillator to make continuous measurements of forces by reading out the Bloch frequency. In this context, we establish the significant result that the optical spring effect is absent and the Bloch frequency is not modified by the backaction.
Hartog, den, J.M.P.
1997-01-01
The genus Amphiprion Bloch & Schneider, 1801, is represented in the Seychelles by two species, A. akallopisos Bleeker, 1853, and the endemic A. fuscocaudatus Allen, 1972. Throughout its distributional range Amphiprion akallopisos has exclusively been recorded to associate with the clownfish anemones Heteractis magnifica (Quoy & Gaimard, 1833) and Stichodactyla mertensii Brandt, 1835. During the Netherlands Indian Ocean Programme (NIOP) Seychelles Expedition 19921993 this was confirmed for the...
Traversing psychological distance.
Liberman, Nira; Trope, Yaacov
2014-07-01
Traversing psychological distance involves going beyond direct experience, and includes planning, perspective taking, and contemplating counterfactuals. Consistent with this view, temporal, spatial, and social distances as well as hypotheticality are associated, affect each other, and are inferred from one another. Moreover, traversing all distances involves the use of abstraction, which we define as forming a belief about the substitutability for a specific purpose of subjectively distinct objects. Indeed, across many instances of both abstraction and psychological distancing, more abstract constructs are used for more distal objects. Here, we describe the implications of this relation for prediction, choice, communication, negotiation, and self-control. We ask whether traversing distance is a general mental ability and whether distance should replace expectancy in expected-utility theories. PMID:24726527
Savoie, Baptiste
2012-01-01
Starting with a nearest-neighbors tight-binding model, we rigorously investigate the bulk zero-field orbital susceptibility of a non-interacting Bloch electrons gas in graphene-like solids at fixed temperature and density of particles. In the zero-temperature limit and in the semiconducting situation, we derive a complete expression which holds for an arbitrary number of bands with possible degeneracies. In the particular case of a two-bands gapped model, all involved quantities are exactly written down. Besides the formula we obtain have the special feature to be suitable for numerical computations since it only involves the eigenvalues and associated eigenfunctions of the Bloch Hamiltonian, together with the derivatives (up to the second order) w.r.t. the quasi-momentum of the matrix-elements of the Bloch Hamiltonian. Finally we give a simple application for the two-bands gapped model by considering the case of a dispersion law which is linear w.r.t. the quasi-momentum in the gapless limit. Through this ins...
MOTIVATION FOR DISTANCE EDUCATION
R zvan TEF NESCU; Dumitriu, Ramona; Liliana MOGA
2009-01-01
Beginning with the 1980’s the new information, communication and computer based technologies stimulated the development of the distance education. In Romania the universities adapted rapidly to this type of learning that became an important financing source for most of them. In this article we approach the causes of attraction for the distance education. For this purpose we use an investigation we did on a group of students at Distance Education including interviews regarding their reasons fo...
Normalized information distance
Vitányi, P.M.B.; Balbach, F.J.; Cilibrasi, R.L.; M. Li
2008-01-01
The normalized information distance is a universal distance measure for objects of all kinds. It is based on Kolmogorov complexity and thus uncomputable, but there are ways to utilize it. First, compression algorithms can be used to approximate the Kolmogorov complexity if the objects have a string representation. Second, for names and abstract concepts, page count statistics from the World Wide Web can be used. These practical realizations of the normalized information distance can then be a...
Ziegler, Gerhard
2011-01-01
Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. This book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a reference guide for s
Shear Bloch waves and coupled phonon-polariton in periodic piezoelectric waveguides.
Piliposyan, D G; Ghazaryan, K B; Piliposian, G T
2014-02-01
Coupled electro-elastic SH waves propagating in a periodic piezoelectric finite-width waveguide are considered in the framework of the full system of Maxwell's electrodynamic equations. We investigate Bloch-Floquet waves under homogeneous or alternating boundary conditions for the elastic and electromagnetic fields along the guide walls. Zero frequency stop bands, trapped modes as well as some anomalous features due to piezoelectricity are identified. For mixed boundary conditions, by modulating the ratio of the length of the unit cell to the width of the waveguide, the minimum widths of the stop bands can be moved to the middle of the Brillouin zone. The dispersion equation has been investigated also for phonon-polariton band gaps. It is shown that for waveguides at acoustic frequencies, acousto-optic coupling gives rise to polariton behavior at wavelengths much larger than the length of the unit cell but at optical frequencies polariton resonance occurs at wavelengths comparable with the period of the waveguide. PMID:24139302
A Bloch wave analysis of optical sectioning in aberration-corrected STEM
International Nuclear Information System (INIS)
The reduction in the focal depth of field that occurs through the use of larger apertures in aberration-corrected STEM allows three-dimensional information to be retrieved by optical depth sectioning. This paper explores depth sectioning in zone-axis crystals using Bloch wave calculations. By decomposing the calculation into the contribution from individual states and from individual partial plane waves in the convergent cone of illumination, we explain the form of the electron intensity in the crystal as a function of depth. Two separate effects are found that can cause the intensity maximum to deviate from that of the expected defocus value. Firstly it is found that the unbound, high angle excited states give rise to a behaviour similar to that of the probe focusing in the vacuum, but with a prefocusing effect due to the lensing effect of the potential of the atomic column. Superimposed upon this prefocused peak is an oscillation due to interference between the channelling 1s state and the rest of the wavefunction. This oscillation can actually prevent an intensity maximum being formed at certain depths in the crystal, and will complicate the interpretation of optical sectioning data
Grating-Coupling-Based Excitation of Bloch Surface Waves for Lab-on-Fiber Nanoprobes
Scaravilli, Michele; Cusano, Andrea; Galdi, Vincenzo
2016-01-01
In this paper, we investigate for the first time the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, we first demonstrate the possibility to exploit a grating-coupling mechanism for on-tip excitation of BSWs, and highlight the flexibility of the proposed design as well as its intrinsic robustness to unavoidable fabrication tolerances. Subsequently, with a view towards label-free chemical and biological sensing, we present an optimized design to maximize the sensitivity (in terms of wavelength shift) of the arising resonances with respect to changes in the refractive properties of the surrounding environment. Numerical results indicate that the attained sensitivities are in line with those exhibited by state-of-the-art plasmonic nanoprobes, with the key advantage of exhibiting much narrower spectral resonances. This prototype study paves the way for a new class of miniaturized high-performance surface-wave fiber-optic devices for high-resolution...
Establishment of a cell line from kidney of seabass, Lates calcarifer (Bloch
Directory of Open Access Journals (Sweden)
Phromkunthong, W.
2003-01-01
Full Text Available Primary cell culture from caudal fin and kidney of seabass (Lates calcarifer Bloch using tissue explant method were cultured in three different medias with various salt concentrations. Only seabass kidney (SK cells grew well in Leibovitze's-15 medium containing 8 g/l of NaCl supplemented with 10 % fetal bovine serum at an optimum temperature of 25 oC. Over a period of 24 months, SK cells were subcultured over than 75 passages and exhibited epithelial-like cells. The chromosome number of SK cells was 42. The cells were found to be free from bacterial, fungal and mycoplasma contamination. Seabass cells can be kept at -80 oC and/or in liquid nitrogen (-196 oC for at least 24 months with a survival rate of 83.20 and 74.50 %, respectively. Nine fish viruses were tested for their infectivity and this SK cells were susceptible to sand goby virus (SGV, chub reovirus (CRV, snake-head rhabdovirus (SHRV, red seabream iridovirus (RSIV, seabass iridovirus (SIV and grouper iridovirus-2 (GIV-2.
Application of Berry's phase to the effective mass of Bloch electrons
International Nuclear Information System (INIS)
Berry's phase, although well known since 1984, has received little attention among textbook authors of solid state physics. We attempt to address this lack by showing how the presence of the Berry's phase significantly changes a standard concept (effective mass) found in most solid state texts. Specifically, we show that the presence of a non-zero Berry curvature in Bloch systems makes the traditional concept of an inverse effective mass tensor M-1 problematic, since a routine application of Newton's second law leads to a circular definition. As a consequence, the related concept of cyclotron effective mass m* also requires modification. It is shown that m* is magnetic-field dependent in non-inversion symmetric systems. This has important ramifications for cyclotron resonance experiments, since such experiments yield m* and thereby purportedly give the components of M-1. This work represents a 'case study' in how Berry's phase effects can modify 'standard' solid-state topics in ways that students and instructors may find surprising.
Mass Spectrum of Fermion on Bloch Branes with New Scalar-fermion Coupling
Xie, Qun-Ying; Zhao, Zhen-Hua; Du, Yun-Zhi; Zhang, Yu-Peng
2015-01-01
In order to localize a left- or right-handed fermion zero mode on a thick brane, one usually introduces the Yukawa coupling $\\eta \\bar{\\Psi} F(\\chi) \\Psi$ between a bulk fermion and the background scalar field $\\chi$. However, the Yukawa coupling will do not work if the background scalar is an even function of the extra dimension. Recently, Ref. [Phy. Rev. \\textbf{D} 89 (2014) 086001] has presented a new scalar-fermion coupling form $\\lambda \\bar \\Psi \\Gamma^M \\partial_M F(\\chi) \\gamma^5 \\Psi$ in order to deal with this problem. In this paper, we investigate the localization and mass spectrum of fermion on the Bloch brane by using the new scalar-fermion coupling with $F(\\chi)=\\chi^n$. It is found that the effective potentials have rich structure and may be volcano-like, finite square well-like, and infinite potentials, which depend on the parameter $n$. As a result, there may appear some resonant KK fermions, finite or infinite numbers of bound KK fermions.
Effects of the projectile electronic structure on Bethe-Bloch stopping parameters for Ag
Moussa, D.; Damache, S.; Ouichaoui, S.
2010-06-01
Energy losses of protons and alpha particles in silver have been accurately measured under the same experimental conditions over the velocity range E=(0.192-2.595) MeV/amu using the transmission method. Deduced S(E) stopping powers are compared to most accurate ones from the literature, to values generated by the SRIM-2008 computer code and to ICRU-49 compilation. They were analyzed in the framework of modified Bethe-Bloch theory for extracting Ag target mean excitation and ionization potential, I, and Barkas effect parameter, b. Values of ( 466±5) eV and 1.20±0.01 for these two parameters were inferred from the proton S(E) data while the alpha particle data yielded values of (438±4) eV and 1.38±0.01, respectively. The ( I, b) stopping parameters thus exhibit opposite variations as the projectile charge increases, similarly as we have found previously for nickel [6]. This can be ascribed only to an effect of the projectile electronic structure at low velocities. The obtained results are discussed in comparison to previous ones reported in the literature.
Bloch oscillations in non-Hermitian lattices with trajectories in the complex plane
Longhi, Stefano
2015-10-01
Bloch oscillation (BO), i.e., the oscillatory motion of a quantum particle in a periodic potential, is one of the most striking effects of coherent quantum transport in matter. In the semiclassical picture, it is well known that BOs can be explained owing to the periodic band structure of the crystal and the so-called acceleration theorem: since in the momentum space the particle wave packet drifts with a constant speed without being distorted, in real space the probability distribution of the particle undergoes a periodic motion following a trajectory which exactly reproduces the shape of the lattice band. In non-Hermitian lattices with a complex (i.e., not real) energy band, extension of the semiclassical model is not intuitive. Here we show that the acceleration theorem holds for non-Hermitian lattices with a complex energy band only on average, and that the periodic wave-packet motion of the particle in real space is described by a trajectory in the complex plane, i.e., it generally corresponds to reshaping and breathing of the wave packet in addition to a transverse oscillatory motion. The concept of BOs involving complex trajectories is exemplified by considering two examples of non-Hermitian lattices with a complex band dispersion relation, including the Hatano-Nelson tight-binding Hamiltonian describing the hopping motion of a quantum particle on a linear lattice with an imaginary vector potential and a tight-binding lattice with imaginary hopping rates.
Directory of Open Access Journals (Sweden)
Muthusamy RAJASEKAR
2012-08-01
Full Text Available Lates calcarifer (Bloch 1790 is one of the major economically important cultivable fish species in India. In this study, three populations of L. calcarifer was selected to assess the genetic diversity. Of which, two wild (Mudaslodai, Muthupettai and one captive (Mutukadu population. The genetic diversity of three populations of this species was studied using Random Amplified Polymorphic DNA (RAPD markers. Ten random primers were used for the assessment of their genetic diversity and construction of the dendrogram. A total of 589 scorable bands were obtained, 93.12% of them were polymorphic. The Nei�s gene diversity (H of two wild populations were more (0.0504 � 0.0670 and 0.0519 � 0.0953 than the captive population (0.0489 � 0.0850. The clustering pattern obtained by UPGMA method emphasized the wild populations were clustered in one clade and captive population was deviated into another clade. This study proved that RAPD analysis has the ability to discriminate L. calcarifer populations. Further molecular studies, comprising a higher number of molecular tools are still required to precisely evaluate the genetic structure of all seabass populations along the Indian coast.
Schubert varieties and distances between subspaces of different dimensions
Ye, Ke; Lim, Lek-Heng
2014-01-01
We resolve a basic problem regarding subspace distances that has arisen considerably often in applications: How could one define a notion of distance between two linear subspaces of different dimensions in a way that generalizes the usual Grassmann distance between equidimensional subspaces? We show that a natural solution is given by the distance of a point to a Schubert variety within the Grassmannian. Aside from reducing to the usual Grassmann distance when the subspaces are equidimensiona...
Deza, Michel Marie
2009-01-01
Distance metrics and distances have become an essential tool in many areas of pure and applied Mathematics. This title offers both independent introductions and definitions, while at the same time making cross-referencing easy through hyperlink-like boldfaced references to original definitions.
Normalized information distance
P.M.B. Vitányi; F.J. Balbach; R.L. Cilibrasi; M. Li
2008-01-01
The normalized information distance is a universal distance measure for objects of all kinds. It is based on Kolmogorov complexity and thus uncomputable, but there are ways to utilize it. First, compression algorithms can be used to approximate the Kolmogorov complexity if the objects have a string
ORDERED WEIGHTED DISTANCE MEASURE
Institute of Scientific and Technical Information of China (English)
Zeshui XU; Jian CHEN
2008-01-01
The aim of this paper is to develop an ordered weighted distance (OWD) measure, which is thegeneralization of some widely used distance measures, including the normalized Hamming distance, the normalized Euclidean distance, the normalized geometric distance, the max distance, the median distance and the min distance, etc. Moreover, the ordered weighted averaging operator, the generalized ordered weighted aggregation operator, the ordered weighted geometric operator, the averaging operator, the geometric mean operator, the ordered weighted square root operator, the square root operator, the max operator, the median operator and the min operator axe also the special cases of the OWD measure. Some methods depending on the input arguments are given to determine the weights associated with the OWD measure. The prominent characteristic of the OWD measure is that it can relieve (or intensify) the influence of unduly large or unduly small deviations on the aggregation results by assigning them low (or high) weights. This desirable characteristic makes the OWD measure very suitable to be used in many actual fields, including group decision making, medical diagnosis, data mining, and pattern recognition, etc. Finally, based on the OWD measure, we develop a group decision making approach, and illustrate it with a numerical example.
Institute of Scientific and Technical Information of China (English)
杨小平; 何伟; 孙亚琳; 廖俊宇
2012-01-01
As a tool of data analysis and formalizing for knowledge management, Formal Concept Analysis! FCA) can effective mine knowledge interested for people from lager textual data, and which are held in esteem by many researchers. The premise of FCA is that need a pure and well defined formal context. Extracting characteristic word directly from the text and exploiting document with characteristic words to form textual formal context(TFC) , which lead to generating a highly sparse two-dimensional table with a lot of noise. It seriously affects efficiency of building concept lattice and the structure of lattice. Therefore, it is necessary to find an effective method for reducing the textual formal context. Comprehensively considering the nature of textual formal context in this paper, we propose a method named TFC-Reducing for the reduction of textual formal context from the view of semantic distance between attributes and mathematical theory, and give a method for evaluating reduction of textual formal context, named as information losses entropy ILE and semantic coverage SC.%形式概念分析作为数据分析和知识处理的形式化工具,可以有效的从海量文本数据中挖掘出人们感兴趣的知识,受到许多研究人员的推崇.形式概念分析的前提条件是必须有一个纯净、良好定义的形式背景.从文本中直接提取特征词,利用文本-特征词形成的文本型形式背景(Textual Formal Context TFC)是一个高度稀疏的二维表,带有很多的噪音信息,严重影响形式概念分析的建格效率以及概念格的结构.因此找到一种有效的文本型形式背景约简方法很有必要.本文综合考虑文本型形式背景的本质特征,从属性语义距离和数学原理出发,提出了一种文本型形式背景的约简方法TFC-Reducing,并给出文本型形式背景约简的评价方法-信息损失熵和语义覆盖度.
Game Theory of Social Distancing in Response to an Epidemic
Timothy C Reluga
2010-01-01
Social distancing practices are changes in behavior that prevent disease transmission by reducing contact rates between susceptible individuals and infected individuals who may transmit the disease. Social distancing practices can reduce the severity of an epidemic, but the benefits of social distancing depend on the extent to which it is used by individuals. Individuals are sometimes reluctant to pay the costs inherent in social distancing, and this can limit its effectiveness as a control m...
Estimating distances from parallaxes
Bailer-Jones, C A L
2015-01-01
Astrometric surveys such as Gaia and LSST will measure parallaxes for hundreds of millions of stars. Yet they will not measure a single distance. Rather, a distance must be estimated from a parallax. In this didactic article, I show that doing this is not trivial once the fractional parallax error is larger than about 20%, which will be the case for about 80% of stars in the Gaia catalogue. Estimating distances is an inference problem in which the use of prior assumptions is unavoidable. I investigate the properties and performance of various priors and examine their implications. A supposed uninformative uniform prior in distance is shown to give very poor distance estimates (large bias and variance). Any prior with a sharp cut-off at some distance has similar problems. The choice of prior depends on the information one has available - and is willing to use - concerning, for example, the survey and the Galaxy. I demonstrate that a simple prior which decreases asymptotically to zero at infinite distance has g...
Estimating Distances from Parallaxes
Bailer-Jones, Coryn A. L.
2015-10-01
Astrometric surveys such as Gaia and LSST will measure parallaxes for hundreds of millions of stars. Yet they will not measure a single distance. Rather, a distance must be estimated from a parallax. In this didactic article, I show that doing this is not trivial once the fractional parallax error is larger than about 20%, which will be the case for about 80% of stars in the Gaia catalog. Estimating distances is an inference problem in which the use of prior assumptions is unavoidable. I investigate the properties and performance of various priors and examine their implications. A supposed uninformative uniform prior in distance is shown to give very poor distance estimates (large bias and variance). Any prior with a sharp cut-off at some distance has similar problems. The choice of prior depends on the information one has available—and is willing to use—concerning, e.g., the survey and the Galaxy. I demonstrate that a simple prior which decreases asymptotically to zero at infinite distance has good performance, accommodates nonpositive parallaxes, and does not require a bias correction.
MOTIVATION FOR DISTANCE EDUCATION
Directory of Open Access Journals (Sweden)
R zvan TEF NESCU
2009-10-01
Full Text Available Beginning with the 1980’s the new information, communication and computer based technologies stimulated the development of the distance education. In Romania the universities adapted rapidly to this type of learning that became an important financing source for most of them. In this article we approach the causes of attraction for the distance education. For this purpose we use an investigation we did on a group of students at Distance Education including interviews regarding their reasons for choosing this type of learning.
Superfidelity and trace distance
Energy Technology Data Exchange (ETDEWEB)
Li, Yuan, E-mail: liyuan0401@yahoo.com.cn [College of Mathematics and Information Science, Shaanxi Normal University, Xi' an 710062 (China)
2012-02-20
Trace distance and superfidelity play an important role in quantum information theory. The aim of this Letter is to consider an inequality involving trace distance and superfidelity in infinite dimension and give a necessary and sufficient condition for equality of this inequality. In addition, some related results involving trace distance and superfidelity are obtained. -- Highlights: ► Give a necessary and sufficient condition for saturation of the superfidelity inequality. ► Obtain the upper and lower perturbation bound between a state and its transformation by a quantum operation. ► Study topology structure induced by superfidelity.
Several Growth Characteristics of an Invasive Cyprinid Fish (Carassius gibelio Bloch, 1782
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Sait BULUT
2013-05-01
Full Text Available Age composition, length-weight relationships, growth, and condition factors of the gibel carp (Carassius gibelio Bloch, 1782 were determined using specimens collected from Seyitler Reservoir between July 2005 to June 2006. A total of 149 gibel carp were observed and examined. The age composition of the samples ranged between I and VII years of age. It has been determined than 82.55% of the obtained samples are comprised of females, 16.11% is comprised of males and 1.34% is comprised of immature. The population is dominated by females able to reproduce gynogenetically. The mean fork lengths and mean weights of the population were 14.8-32.5 cm and 43.1-807.3 g respectively. The length-weight relation were calculated as W = 0.0696 L2.132, r=0.838 for females, for males W = 0.2942 L2.6417 r=0.784 and W = 0.0274 L2.9382, r=0.813 for all samples. The mean Fulton Condition Factor was calculated as 2.342 for females, 2.064 for males and 2.276 for all samples. Age-length and age-weight relations were determined according to von Bertalanffy growth equation formula. Growth parameters of the population were Lt = 48.09 [1-e-0.093(t+0.29], and Wt=2323.62 [1-e-0.093(t+0.29]2.9382. The growth performance index value (Ø´ was computed as 5.37 for all specimens.
Institute of Scientific and Technical Information of China (English)
Palanivel Bharadhirajan; Natarajan Periyasamy; Sambantham Murugan
2014-01-01
Objective: To assess the nutritions in Mene maculata (Bloch & Schneider, 1801) (M. maculata). Methods: Fishes (14-16 cm) were obtained from the landings at Parangipettai for the evaluation of biochemical composition. The present study deals with biochemical composition such as protein, carbohydrate, lipid, amino acids fatty acids, vitamins and minerals which were evaluated in the moonfish.Results:protein was high in the tissue (23.16%), followed by the carbohydrate (1.3%) and lipid (2.62%). Totally 20 essential and nonessential amino acids were present at the rate of 46.72% and 43.91%. In the analysis, the fatty acid profile by gas chromatography revealed the presence of higher amount of saturated fatty acid (palmitic acid 22.17%) than monounsaturated fatty acid (oleic acid 14.51%) and polyunsaturated fatty acid (alpha linolenic acid 16.07%). Vitamins were detected in M. maculata. Among them, vitamin A was found in higher levels (124.5 mg/g), whereas vitamin B6 was noticed as lower levels (0.34 mg/g). In the present study, totally 5 macro minerals and 2 trace minerals were reported. The macro mineral calcium (156.7 mg/g) was found at the highest level and other minerals such as sodium (31.98 mg/g), potassium (21.33 mg/g), copper (1.43 mg/g) and magnesium (0.341 mg/g) were also detected in the moonfish.Conclusions:The results of proximate composition in M. maculata showed that the percentage of The result showed that the moonfish M. maculata tissue is a valuable food recipe for human consumption, due to its high quality protein and well-balanced amino acids.
Directory of Open Access Journals (Sweden)
Palanivel Bharadhirajan
2014-01-01
Full Text Available Objective: To assess the nutritions in Mene maculata (Bloch & Schneider, 1801 (M. maculata. Methods: Fishes (14-16 cm were obtained from the landings at Parangipettai for the evaluation of biochemical composition. The present study deals with biochemical composition such as protein, carbohydrate, lipid, amino acids fatty acids, vitamins and minerals which were evaluated in the moonfish. Results: The results of proximate composition in M. maculata showed that the percentage of protein was high in the tissue (23.16%, followed by the carbohydrate (1.3% and lipid (2.62%. Totally 20 essential and nonessential amino acids were present at the rate of 46.72% and 43.91%. In the analysis, the fatty acid profile by gas chromatography revealed the presence of higher amount of saturated fatty acid (palmitic acid 22.17% than monounsaturated fatty acid (oleic acid 14.51% and polyunsaturated fatty acid (alpha linolenic acid 16.07%. Vitamins were detected in M. maculata. Among them, vitamin A was found in higher levels (124.5 mg/g, whereas vitamin B6 was noticed as lower levels (0.34 mg/g. In the present study, totally 5 macro minerals and 2 trace minerals were reported. The macro mineral calcium (156.7 mg/g was found at the highest level and other minerals such as sodium (31.98 mg/g, potassium (21.33 mg/g, copper (1.43 mg/g and magnesium (0.341 mg/g were also detected in the moonfish. Conclusions: The result showed that the moonfish M. maculata tissue is a valuable food recipe for human consumption, due to its high quality protein and well-balanced amino acids.
International Nuclear Information System (INIS)
This paper examines the challenges and rewards that can arise when the teaching of Einsteinian physics has to be accomplished by means of distance education. The discussion is mainly based on experiences gathered over the past 35 years at the UK Open University, where special and general relativity, relativistic cosmology and other aspects of Einsteinian physics, have been taught at a variety of levels, and using a range of techniques, to students studying at a distance
Information distance: New developments
Vitányi, Paul
2012-01-01
In pattern recognition, learning, and data mining one obtains information from information-carrying objects. This involves an objective definition of the information in a single object, the information to go from one object to another object in a pair of objects, the information to go from one object to any other object in a multiple of objects, and the shared information between objects. This is called "information distance." We survey a selection of new developments in information distance.
Venkatesh, B Prasanna; Goldwin, J
2015-01-01
We analyze the optomechanics of an atomic Bose-Einstein condensate interacting with the optical lattice inside a laser-pumped optical cavity and subject to a uniform bias force such as gravity. An atomic wave packet in a tilted lattice undergoes Bloch oscillations; in a cavity the backaction of the atoms on the light leads to a time-dependent modulation of the intracavity lattice at the Bloch frequency. When the Bloch frequency is on the order of the cavity damping rate we find transport of the atoms either up or down the lattice. The transport dynamics can be interpreted as a manifestation of dynamical backaction-induced sideband damping/amplification of the optomechanical Bloch oscillator. Depending on the sign of the pump-cavity detuning, atoms are transported either with or against the bias force accompanied by an up- or down-conversion of the frequency of the pump laser light. We also evaluate the prospects for using the optomechanical Bloch oscillator to make continuous measurements of forces by reading...
Antes, desde y para el exilio. Herencia de esta época (1935/1962 de Ernst Bloch
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Salmerón Infante, Miguel
2009-10-01
Full Text Available The first edition of Erbschaft dieser Zeit was published in Zurich in 1935, during Ernst Bloch’s five-year period of emigration from Nazi-Germany in various European capitals before his final emigration to America for ten years in 1938. In this book Bloch made a courageous stand in defence of the artistic avant-garde against the dogmatic advocates of socialist realism. His particularly adversary was Georg Lukács. But of course one of the most fascinating aspects of the book is that is also reads as a contemporary observation of the rise of the Nazis. Erbschaft is undoubtedly the major work of Weimar Germany Exile.La primera edición de Erbschaft dieser Zeit fue publicada en 1935 en Zurich, durante la emigración de Ernst Bloch de la Alemania nazi por un período de cinco años en el que residió en varias capitales europeas antes de su marcha definitiva a América en 1938, donde vivió diez años. En este libro Bloch hace una encorajinada defensa de la vanguardia artística contra los abogados del realismo socialista. Su adversario específico era Georg Lukács. Pero sin duda alguna uno de los aspectos más fascinantes de este libro es que puede leerse como una observación contemporánea de la ascensión al poder de los nazis. Erbschaft es indudablemente la obra clave del exilio de la Alemania de Weimar.
Haddouk, Lise
2015-01-01
Nowadays in the context of the cyberculture, computer-mediated inter-subjective relationships are part of our everyday lives, in both the professional and personal spheres, and for all age groups. In the clinical field, many applications have been developed to facilitate the exchange of informations and mediate the relationship between patient and therapist. In psychology, more or less immersive technologies are used, to encourage the feeling of presence among the users, and to trigger certain psychological processes. In our research, we have explored the remote clinical interview through videoconferencing, with the development and utilisation of the iPSY platform, totally focused on this objective. In this context, we have considered the notion of intersubjectivity, despite the physical absence. This research is leading us today to envision the notions of distance and presence, and possibly to redefine them. Thus, can we still oppose physical distance to psychological distance? Can we still affirm that the physical absence does not permit a psychological co-presence in certain interactions, like this observed in video interviews? The results show that the psychological processes, activated in this context, are similar to those observed in "traditional" clinical consults between the patient and the therapist. However, certain specifics have led us to consider the concept of distance, here influenced by the framework, and to observe its effects. This distance could possibly constitute a therapeutic lever for some patients, notably for those who have difficulties establishing the right psychological distance in their relationships with others. According to these results, can "distance" still be opposed to "presence", or could it be re-defined? This also opens up questions on the more general concept of digital relationships, and the definition of their specificities. PMID:26799909
Lawrence, Felix J; Dossou, Kokou B; McPhedran, R C; de Sterke, C Martijn
2011-01-01
We present a flexible method that can calculate Bloch modes, complex band structures, and impedances of two-dimensional photonic crystals from scattering data produced by widely available numerical tools. The method generalizes previous work which relied on specialized multipole and FEM techniques underpinning transfer matrix methods. We describe the numerical technique for mode extraction, and apply it to calculate a complex band structure and to design two photonic crystal antireflection coatings. We do this for frequencies at which other methods fail, but which nevertheless are of significant practical interest.
RELACIONES TALLA-PESO DEL BARBUL (Pimelodus clarias f.c. Bloch, 1785) EN LA CUENCA DEL RIO SINU,
Iliana Santos-Sanes,; Charles Olaya-Nieto; Fredys Segura-Guevara; Samir Brú-Cordero; Glenys Tordecilla-Petro
2006-01-01
Objetivo. Establecer las relaciones de talla y peso del barbul (Pimelodus clarias) en la cuenca del río Sinú. Materiales y Métodos. Se estimaron las relaciones talla-peso de 4324 individuos de Barbul (Pimelodus clarias f.c. Bloch, 1785) colectados entre enero 2000 y diciembre 2002. Resultados. La longitud total (LT) osciló entre 13.0-30.0 cm, promedio de 19.5 (±1.6) cm y el peso total (WT) entre 20.0 y 248.1 g, promedio de 65.8 (±23.2) g. Las relaciones lineales estimadas fueron: LT = 1.92 (�...
Bloch k-selective resonant inelastic scattering of hard X-rays from valence electrons of 3d-metals
Enkisch, Hartmut
2002-01-01
Die Form von resonant angeregen Valenz-Fluoreszenzspektren hängt sowohl vonder Energie der einfallenden Strahlung, als auch von Größe und Richtung desImpulsübertrags q ab, falls harte Röntgenstrahlen benutzt werden. DieserEffekt ist auf die elektronische Bandstruktur der Valenz- undLeitungselektronen der Probe, in Kombination mit der Energie- undImpulserhaltung des Streuprozesses zurückzuführen, woraus dieBloch-k-Impulserhaltung des resonant inelastischen Streuprozesses folgt.In dieser Arbeit...
DEFF Research Database (Denmark)
Breinbjerg, Olav; Yaghjian, Arthur D.
For an infinite 1D periodic structure with unit cells consisting of two planar slabs of magnetodielectric materials, the electric field – as well as magnetic field, electric flux density, magnetic flux density, polarization, and magnetization – can be expressed as infinite series of Floquet......-Bloch space harmonics. We discuss how space harmonic permittivity and permeability can be expressed in seemingly different though equivalent forms, and we investigate these parameters of the zeroeth order space harmonic for a particular 1D periodic structure that is based on a previously reported 3D periodic...
International Nuclear Information System (INIS)
With the aid of symbolic computation, the coupled Hirota-Maxwell-Bloch system is investigated with third-order dispersion and higher-order nonlinear effects, which govern the nonlinear pulse propagation in an erbium-doped optical fiber medium. In addition, the Lax pair for the system is explicitly constructed and the soliton-like solutions are derived using the Darboux transformation, which makes it possible to generate the multi-soliton solutions in a recursive manner. Through the graphical analysis of some obtained analytic one- and two-soliton-like solutions, stable propagation and collision between two solitons are discussed. Furthermore, the conservation laws for the system are presented.
Zhang, Wen-Zhuo
2012-01-01
We derive a set of optical Bloch equations (OBEs) directly from the minimal-coupling Hamiltonian density of the bound-state quantum electrodynamics (bound-state QED). Such optical Bloch equations are beyond the former widely-used ones due to that there is no electric dipole approximation (EDA) on the minimal-coupling Hamiltonian density of the bound-state QED. Then our optical Bloch equations can describe a two-level atom interacting with a monochromatic light of arbitrary wavelength, which are suitable to study the spectroscopy and the Rabi oscillations of two-level atoms in X-ray laser beams since that the wavelength of X-ray is close to an atom to make the electric dipole approximation (EDA) invalid.
Directory of Open Access Journals (Sweden)
Vidadi Yusibov
2013-07-01
Full Text Available Alfalfa mosaic virus (AlMV RNAs 1 and 2 with deletions in their 3' non‑translated regions (NTRs have been previously shown to be encapsidated into virions by coat protein (CP expressed from RNA3, indicating that the 3' NTRs of RNAs 1 and 2 are not required for virion assembly. Here, we constructed various mutants by deleting sequences within the 3' NTR of AlMV subgenomic (sg RNA4 (same as of RNA3 and examined the effect of these deletions on replication and translation of chimeric Tobacco mosaic virus (TMV expressing AlMV sgRNA4 from the TMV CP sg promoter (Av/A4 in tobacco protoplasts and Nicotiana benthamiana plants. While the Av/A4 mutants were as competent as the wild-type Av/A4 in RNA replication in protoplasts, their encapsidation, long-distance movement and virus accumulation varied significantly in N. benthamiana. These data suggest that the 3' NTR of AlMV sgRNA4 contains potential elements necessary for virus encapsidation.
Roy, Gourgopal; Fedorkin, Oleg; Fujiki, Masaaki; Skarjinskaia, Marina; Knapp, Elisabeth; Rabindran, Shailaja; Yusibov, Vidadi
2013-07-01
Alfalfa mosaic virus (AlMV) RNAs 1 and 2 with deletions in their 3' non‑translated regions (NTRs) have been previously shown to be encapsidated into virions by coat protein (CP) expressed from RNA3, indicating that the 3' NTRs of RNAs 1 and 2 are not required for virion assembly. Here, we constructed various mutants by deleting sequences within the 3' NTR of AlMV subgenomic (sg) RNA4 (same as of RNA3) and examined the effect of these deletions on replication and translation of chimeric Tobacco mosaic virus (TMV) expressing AlMV sgRNA4 from the TMV CP sg promoter (Av/A4) in tobacco protoplasts and Nicotiana benthamiana plants. While the Av/A4 mutants were as competent as the wild-type Av/A4 in RNA replication in protoplasts, their encapsidation, long-distance movement and virus accumulation varied significantly in N. benthamiana. These data suggest that the 3' NTR of AlMV sgRNA4 contains potential elements necessary for virus encapsidation. PMID:23867804
Gherase, Mihai R
2012-01-01
Diffusive spin exchange is one of the most important relaxation mechanisms in the Nuclear Magnetic Resonance (NMR) applications to medicine and biology. Two models based on the Bloch-McConnell (B-M) and the Bloch-Torrey (B-T) equations are commonly used for modelling the physical processes which determine the NMR lineshapes. Qualitative arguments for each of the two methods can be found in various studies in the literature. However, there is a lack of systematic quantitative investigations of the diffusive exchange spectra calculated with the two methods for the same physical system or model. In this work exact frequency-domain transverse magnetization solutions of the B-M and the B-T equations with boundary conditions for a two-compartment radial diffusive exchange model are presented. Theoretical spectra and the two corresponding metrics were computed by varying three different parameters: diffusive permeability of the separating membrane between the two compartments (P), the radius of the inner spherical c...
Institute of Scientific and Technical Information of China (English)
马速良; 马会萌; 蒋小平; 段国栋; 李娜
2015-01-01
风电功率波动对电网造成不容忽视的影响。风电并网处加入混合储能系统可有效降低风电对电网的影响。首先， 有效地分解风电有功功率，得到混合储能系统需平抑的波动功率；然后，在电池及超级电容器荷电状态、额定功率及充放电时间的允许范围内实现超级电容器优先充放电的协调控制方式；最后，应用映射于Bloch球面的量子遗传算法，确定满足混合储能系统技术要求及工程指标的混合储能系统配置方案，使混合储能系统成本最低。算例分析证明了在监测荷电状态等约束条件下，优先超级电容器充放电控制方式的有效性及 Bloch 球面量子遗传算法配置混合储能系统方法的合理性。%It can not be ignored that active power fluctuations in wind power's influence on the grid. The hybrid energy storage system access to the place in which wind power connected to the power grid can effectively reduce the impact of the intermittency of wind power. Firstly, the fluctuating power of wind power was separated to derive the output power of the hybrid energy storage system Secondly, charging and discharging of the super-capacitor were firstly controlled in the allowable range of the power rating, the states of charge and the durations of charging or discharging of the hybrid energy storage. At last, the Bloch spherical quantum genetic algorithm was applied to decide the combination scheme of hybrid energy storage system to meet the technical requirements of hybrid energy storage system and engineering indicators and make the cost be the lowest. In the example, the validity of the control model based on priority control of super-capacitor charging and discharging and the effectiveness of configuring hybrid energy storage system capacity with the Bloch spherical quantum genetic algorithm was proved.
Sets avoiding integral distances
Kurz, Sascha
2012-01-01
We study open point sets in Euclidean spaces $\\mathbb{R}^d$ without a pair of points an integral distance apart. By a result of Furstenberg, Katznelson, and Weiss such sets must be of Lebesgue upper density zero. We are interested in how large such sets can be in $d$-dimensional volume. We determine the lower and upper bounds for the volumes of the sets in terms of the number of their connected components and dimension, and also give some exact values. Our problem can be viewed as a kind of inverse to known problems on sets with pairwise rational or integral distances.
Distances of Heegaard splittings
Abrams, Aaron; Schleimer, Saul
2003-01-01
J Hempel [Topology, 2001] showed that the set of distances of the Heegaard splittings (S,V, h^n(V)) is unbounded, as long as the stable and unstable laminations of h avoid the closure of V in PML(S). Here h is a pseudo-Anosov homeomorphism of a surface S while V is the set of isotopy classes of simple closed curves in S bounding essential disks in a fixed handlebody. With the same hypothesis we show the distance of the splitting (S,V, h^n(V)) grows linearly with n, answering a question of A C...
Exploring characteristics and motives of long distance commuter cyclists
DEFF Research Database (Denmark)
Hansen, Karsten Bruun; Sick Nielsen, Thomas
2014-01-01
, commuter cyclists (45 km from home to work) have more mobility options, higher incomes, and a longer education than other commuter cyclists. The main motive for longer distance cycling is physical exercise, followed by reduced costs and time used for traveling. The long distance commuter cyclists surveyed......Longer distance cycling is a commuting mode that contributes to sustainability and public health objectives, but little is known about current long distance cyclist's motives. The paper explores longer distance commuter cyclists, their characteristics, practice and motives. Longer distance...
Web-based description of the space radiation environment using the Bethe-Bloch model
Cazzola, Emanuele; Calders, Stijn; Lapenta, Giovanni
2016-01-01
Space weather is a rapidly growing area of research not only in scientific and engineering applications but also in physics education and in the interest of the public. We focus especially on space radiation and its impact on space exploration. The topic is highly interdisciplinary, bringing together fundamental concepts of nuclear physics with aspects of radiation protection and space science. We give a new approach to presenting the topic by developing a web-based application that combines some of the fundamental concepts from these two fields into a single tool that can be used in the context of advanced secondary or undergraduate university education. We present DREADCode, an outreach or teaching tool to rapidly assess the current conditions of the radiation field in space. DREADCode uses the available data feeds from a number of ongoing space missions (ACE, GOES-13, GOES-15) to produce a first order approximation of the radiation dose an astronaut would receive during a mission of exploration in deep space (i.e. far from the Earth’s shielding magnetic field and from the radiation belts). DREADCode is based on an easy-to-use GUI interface available online from the European Space Weather Portal (www.spaceweather.eu/dreadcode). The core of the radiation transport computation to produce the radiation dose from the observed fluence of radiation observed by the spacecraft fleet considered is based on a relatively simple approximation: the Bethe-Bloch equation. DREADCode also assumes a simplified geometry and material configuration for the shields used to compute the dose. The approach is approximate and sacrifices some important physics on the altar of rapid execution time, which allows a real-time operation scenario. There is no intention here to produce an operational tool for use in space science and engineering. Rather, we present an educational tool at undergraduate level that uses modern web-based and programming methods to learn some of the most important
Scalable Parallel Distance Field Construction for Large-Scale Applications.
Yu, Hongfeng; Xie, Jinrong; Ma, Kwan-Liu; Kolla, Hemanth; Chen, Jacqueline H
2015-10-01
Computing distance fields is fundamental to many scientific and engineering applications. Distance fields can be used to direct analysis and reduce data. In this paper, we present a highly scalable method for computing 3D distance fields on massively parallel distributed-memory machines. A new distributed spatial data structure, named parallel distance tree, is introduced to manage the level sets of data and facilitate surface tracking over time, resulting in significantly reduced computation and communication costs for calculating the distance to the surface of interest from any spatial locations. Our method supports several data types and distance metrics from real-world applications. We demonstrate its efficiency and scalability on state-of-the-art supercomputers using both large-scale volume datasets and surface models. We also demonstrate in-situ distance field computation on dynamic turbulent flame surfaces for a petascale combustion simulation. Our work greatly extends the usability of distance fields for demanding applications. PMID:26357251
Distances to star forming regions
Loinard, Laurent
2014-01-01
The determination of accurate distances to star-forming regions are discussed in the broader historical context of astronomical distance measurements. We summarize recent results for regions within 1 kpc and present perspectives for the near and more distance future.
Directory of Open Access Journals (Sweden)
Alexander V. Baryshev
2014-12-01
Full Text Available A one-dimensional photonic crystal (PhC with termination by a metal film—a plasmonic photonic-crystal slab—has been theoretically analyzed for its optical response at a variation of the dielectric permittivity of an analyte and at a condition simulating the molecular binding event. Visualization of the Bloch surface wave resonance (SWR was done with the aid of plasmon absorption in a dielectric/metal/dielectric sandwich terminating a PhC. An SWR peak in spectra of such a plasmonic photonic crystal (PPhC slab comprising a noble or base metal layer was shown to be sensitive to a negligible variation of refractive index of a medium adjoining to the slab. As a consequence, the considered PPhC-based optical sensors exhibited an enhanced sensitivity and a good robustness in comparison with the conventional surface-plasmon and Bloch surface wave sensors. The PPhC biosensors can be of practical importance because the metal layer is protected by a capping dielectric layer from contact with analytes and, consequently, from deterioration.
DEFF Research Database (Denmark)
Pedersen, Knud Ole Helgesen
1999-01-01
A method for implementing a digital distance relay in the power system is described.Instructions are given on how to program this relay on a 80537 based microcomputer system.The problem is used as a practical case study in the course 53113: Micocomputer applications in the power system.The relay is...
Minsky, Yair; Moriah, Yoav; Schleimer, Saul
2006-01-01
We construct knots in S^3 with Heegaard splittings of arbitrarily high distance, in any genus. As an application, for any positive integers t and b we find a tunnel number t knot in the three-sphere which has no (t,b)-decomposition.
Personalizing Distance Learning
Coombs-Richardson, Rita
2007-01-01
This article discusses how a personal approach to online learning can yield a successful experience for adults earning advanced degrees or certification in teaching. Distance learning has become increasingly popular among learners with family and work obligations. Degree-seeking adult learners appreciate the flexibility and convenience of learning…
DEFF Research Database (Denmark)
Hansen, Finn J. S.; Clausen, Christian
2001-01-01
The case study represents an example of a top-down introduction of distance teaching as part of Danish trials with the introduction of multimedia in education. The study is concerned with the background, aim and context of the trial as well as the role and working of the technology and the...
Nerbonne, J.; Kleiweg, P.
2003-01-01
The Linguistic Atlas of the Middle and South Atlantic States (LAMSAS) is admirably accessible for reanalysis (see http://hyde.park.uga.edu/lamsas/, Kretzschmar, 1994). The present paper applies a lexical distance measure to assess the lexical relatedness of LAMSAS's sites, a popular focus of investi
Rahman, Monsurur; Karim, Reza; Byramjee, Framarz
2015-01-01
Many educational institutions in the United States are currently offering programs through distance learning, and that trend is rising. In almost all spheres of education a developing country like Bangladesh needs to make available the expertise of the most qualified faculty to her distant people. But the fundamental question remains as to whether…
Institute of Scientific and Technical Information of China (English)
陈锦锐
2013-01-01
Due to the large amount of exercise, long persistent time, and huge energy consumption, athletes are prone to fatigue and consume too much nutrition in long distance running. There-fore, reasonable nutritional supplement helps to restore physical fitness and effectively relieve fatigue. This paper preliminarily discusses how higher vocational students' reduce fatigue and supplement nutrition in long distance running, aiming to improve the quality and efficiency of higher vocational students' long dis-tance running.% 在长跑运动中，由于运动量较大，持续性时间较长，能量消耗巨大，容易导致疲劳，营养消耗过多；因此合理地补充营养，有助于恢复体能，可以有效缓解疲劳。文中就高职学生开展长跑运动项目时，如何减缓疲劳以及补充营养等问题进行了初步的探讨，目的在于提高高职院校学生长跑运动训练的质量和效率。
Institute of Scientific and Technical Information of China (English)
陈锦锐
2013-01-01
在长跑运动中，由于运动量较大，持续性时间较长，能量消耗巨大，容易导致疲劳，营养消耗过多；因此合理地补充营养，有助于恢复体能，可以有效缓解疲劳。文中就高职学生开展长跑运动项目时，如何减缓疲劳以及补充营养等问题进行了初步的探讨，目的在于提高高职院校学生长跑运动训练的质量和效率。%Due to the large amount of exercise, long persistent time, and huge energy consumption, athletes are prone to fatigue and consume too much nutrition in long distance running. There-fore, reasonable nutritional supplement helps to restore physical fitness and effectively relieve fatigue. This paper preliminarily discusses how higher vocational students' reduce fatigue and supplement nutrition in long distance running, aiming to improve the quality and efficiency of higher vocational students' long dis-tance running.
Rabaglia, Cristina D; Maglio, Sam J; Krehm, Madelaine; Seok, Jin H; Trope, Yaacov
2016-07-01
Human languages may be more than completely arbitrary symbolic systems. A growing literature supports sound symbolism, or the existence of consistent, intuitive relationships between speech sounds and specific concepts. Prior work establishes that these sound-to-meaning mappings can shape language-related judgments and decisions, but do their effects generalize beyond merely the linguistic and truly color how we navigate our environment? We examine this possibility, relating a predominant sound symbolic distinction (vowel frontness) to a novel associate (spatial proximity) in five studies. We show that changing one vowel in a label can influence estimations of distance, impacting judgment, perception, and action. The results (1) provide the first experimental support for a relationship between vowels and spatial distance and (2) demonstrate that sound-to-meaning mappings have outcomes that extend beyond just language and can - through a single sound - influence how we perceive and behave toward objects in the world. PMID:27062226
Jones, Kyle M.; Randtke, Edward A.; Howison, Christine M.; Pagel, Mark D.
2016-03-01
We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion.
The proximal distance algorithm
Lange, Kenneth; Keys, Kevin L.
2015-01-01
The MM principle is a device for creating optimization algorithms satisfying the ascent or descent property. The current survey emphasizes the role of the MM principle in nonlinear programming. For smooth functions, one can construct an adaptive interior point method based on scaled Bregmann barriers. This algorithm does not follow the central path. For convex programming subject to nonsmooth constraints, one can combine an exact penalty method with distance majorization to create versatile a...
Distance and Traditional Education
Liu, Yuliang
2002-01-01
This case study is designed to investigate how distance education technology affects the instructor’s simultaneously teaching the same course via instructional television (ITV) and traditional education (face-to-face) formats. This study involved random observations of the instructor in a graduate course in both instructional television and face-to-face classrooms. In addition, an interview with the instructor was conducted to collect more data. This study has suggested that the instructor wh...
Capachi, Casey
2013-01-01
Distance to Cure A three-part television series by Casey Capachi www.distancetocure.com Abstract How far would you go for health care? This three-part television series, featuring two introductory segments between each piece, focuses on the physical, cultural, and political obstacles facing rural Native American patients and the potential of health technology to break down those barriers to care. Part one,Telemedici...
Towards Secure Distance Bounding
Boureanu, Ioana; Mitrokotsa, Aikaterini; Vaudenay, Serge
2013-01-01
Relay attacks (and, more generally, man-in-the-middle attacks) are a serious threat against many access control and payment schemes. In this work, we present distance-bounding protocols, how these can deter relay attacks, and the security models formalizing these protocols. We show several pitfalls making existing protocols insecure (or at least, vulnerable, in some cases). Then, we introduce the SKI protocol which enjoys resistance to all popular attack-models and features provable security....
International Nuclear Information System (INIS)
This paper describes an analytical method for the wave field induced by a moving load on a periodically supported beam. The Green's function for an Euler beam without support is evaluated by using the direct integration. Afterwards, it introduces the supports into the model established by using the superposition principle which states that the response from all the sleeper points and from the external point force add up linearly to give a total response. The periodicity of the supports is described by Bloch's theorem. The homogeneous system thus obtained represents a linear differential equation which governs rail response. It is initially solved in the homogeneous case, and it admits a no null solution if its determinant is null, this permits the establishment the dispersion equation to Bloch waves and wave bands. The Bloch waves and dispersion curves contain all the physics of the dynamic problem and the wave field induced by a dynamic load applied to the system is finally obtained by decomposition into Bloch waves, similarly to the usual decomposition into dynamic modes on a finite structure. The method is applied to obtain the field induced by a load moving at constant velocity on a thin beam supported by periodic elastic supports.
Padmanabha Chakrabarti; Saroj Kumar Ghosh
2015-01-01
The histological analysis, disposition and histochemical localization of tryptophan were investigated in the pancreas to compare the cellular organization and histochemical characterization in the pancreas of Labeo rohita (Hamilton, 1822), Mystus vittatus (Bloch, 1790) and Notopterus notopterus (Pallas, 1769) having different feeding habits. Histological analysis demonstrated that the exocrine pancreatic tissues were dispersed within the hepatic parenchyma and spleen in L. rohita. Thin septa ...
Euclidean distance geometry and applications
Liberti, Leo; Lavor, Carlile; Maculan, Nelson; Mucherino, Antonio
2012-01-01
Euclidean distance geometry is the study of Euclidean geometry based on the concept of distance. This is useful in several applications where the input data consists of an incomplete set of distances, and the output is a set of points in Euclidean space that realizes the given distances. We survey some of the theory of Euclidean distance geometry and some of the most important applications: molecular conformation, localization of sensor networks and statics.
Awojoyogbe, Bamidele O; Dada, Michael O; Onwu, Samuel O; Ige, Taofeeq A; Akinwande, Ninuola I
2016-04-01
Magnetic resonance imaging (MRI) uses a powerful magnetic field along with radio waves and a computer to produce highly detailed "slice-by-slice" pictures of virtually all internal structures of matter. The results enable physicians to examine parts of the body in minute detail and identify diseases in ways that are not possible with other techniques. For example, MRI is one of the few imaging tools that can see through bones, making it an excellent tool for examining the brain and other soft tissues. Pulsed-field gradient experiments provide a straightforward means of obtaining information on the translational motion of nuclear spins. However, the interpretation of the data is complicated by the effects of restricting geometries as in the case of most cancerous tissues and the mathematical concept required to account for this becomes very difficult. Most diffusion magnetic resonance techniques are based on the Stejskal-Tanner formulation usually derived from the Bloch-Torrey partial differential equation by including additional terms to accommodate the diffusion effect. Despite the early success of this technique, it has been shown that it has important limitations, the most of which occurs when there is orientation heterogeneity of the fibers in the voxel of interest (VOI). Overcoming this difficulty requires the specification of diffusion coefficients as function of spatial coordinate(s) and such a phenomenon is an indication of non-uniform compartmental conditions which can be analyzed accurately by solving the time-dependent Bloch NMR flow equation analytically. In this study, a mathematical formulation of magnetic resonance flow sequence in restricted geometry is developed based on a general second order partial differential equation derived directly from the fundamental Bloch NMR flow equations. The NMR signal is obtained completely in terms of NMR experimental parameters. The process is described based on Bessel functions and properties that can make it
Directory of Open Access Journals (Sweden)
Luciano Neves dos Santos
2001-07-01
Full Text Available The diet of Cichla monoculus (Bloch & Schneider, 1801 in Lajes's Reservoir, a major impoundment in Rio de Janeiro State, Brazil, was assessed, from fishes collected in 1994,1996 and 1999/2000. Gut contents in individuals was analyzed by the index of relative importance (IRI which deals with numerical, gravimetrical and frequency of occurrence. Cichla monoculus showed a strong piscivorous habits feeding on Cichlidae, Characidae and Pimelodidae, in decreasing order of importance, with a remarkable cannibalism on young-of-the-year. Others minor items in the diet were Macrobrachium sp. and Odonata. Changes in feeding composition varied with reservoir's zones and seasons, with higher diversity in Autumn and peaks of cannibalism in lower zone during Spring/Summer. Overall, only one third of fish species composition in the reservoir are predated by C. monoculus. Condition factor (k and fullness index varied closely with higher values in lower zone, and lower records in Winter.
2007-01-01
Using the unique orbit of NASA's Spitzer Space Telescope and a depth-perceiving trick called parallax, astronomers have determined the distance to an invisible Milky Way object called OGLE-2005-SMC-001. This artist's concept illustrates how this trick works: different views from both Spitzer and telescopes on Earth are combined to give depth perception. Our Milky Way galaxy is heavier than it looks, and scientists use the term 'dark matter' to describe all the 'heavy stuff' in the universe that seems to be present but invisible to our telescopes. While much of this dark matter is likely made up of exotic materials, different from the ordinary particles that make up the world around us, some may consist of dark celestial bodies -- like planets, black holes, or failed stars -- that do not produce light or are too faint to detect from Earth. OGLE-2005-SMC-001 is one of these dark celestial bodies. Although astronomers cannot see a dark body, they can sense its presence from the way light acts around it. When a dark body like OGLE-2005-SMC-001 passes in front of a bright star, its gravity causes the background starlight to bend and brighten, a process called gravitational microlensing. When the observing telescope, dark body, and star system are closely aligned, the microlensing event reaches maximum, or peak, brightness. A team of astronomers first sensed OGLE-2005-SMC-001's presence when it passed in front of a star in a neighboring satellite galaxy called the Small Magellanic Cloud. In this artist's rendering, the satellite galaxy is depicted as the fuzzy structure sitting to the left of Earth. Once they detected this microlensing event, the scientists used Spitzer and the principle of parallax to figure out its distance. Humans naturally use parallax to determine distance. Each eye sees the distance of an object differently. The brain takes each eye's perspective and instantaneously calculates how far away the object is. To determine OGLE-2005-SMC-001's distance
International Nuclear Information System (INIS)
The equations of fluid mechanics, coupled with those that describe matter transportation at the molecular level must be handled effectively. Putting the fluid into equations, we model the Bloch NMR flow equations into the harmonic wave equation for the analysis of general fluid flow. We derived the solution of the modelled harmonic equation in non relativistic quantum mechanics and discuss its semi classical application to illustrate its potential wide-ranging usefulness in the search for the best possible data obtainable for general fluid flow analysis. Representing the solution of the derived harmonic wave equation by a normalized state function is quite useful in generating the properly normalized wave functions and in the efficient evaluation of expectation values of many operators that can be fundamental to the analysis of fluid flow especially at the microscopic level. (author)
Ammi, H.; Zemih, R.; Mammeri, S.; Allab, M.
2005-04-01
Recent stopping power measurements in thin polymeric films have been performed for protons of 0.4-3.5 MeV energies using the indirect transmission technique [H. Ammi, S. Mammeri, M. Chekirine, B. Bouzid, M. Allab, Nucl. Instr. and Meth. B 198 (2002) 5]. Experimental stopping data have been analyzed with the modified Bethe-Bloch formula and the mean excitation energies I have been then extracted from the data. Resulting values for each thin film are 76 ± 1 eV in Mylar, 70.8 ± 1 eV in Makrofol, 82.2 ± 1.2 eV in LR-115 and 55.4 ± 1 eV in Polypropylene. The I-extracted values are compared to those IB calculated by using the Bragg's rule.
Sych, Denis V.; Grishanin, Boris A.; Zadkov, Victor N.
2005-06-01
Possibilities of improving characteristics of quantum key distribution (QKD) protocols via variation of character set in quantum alphabets are investigated. QKD protocols with discrete alphabets letters of which form regular polyhedrons on the Bloch sphere (tetrahedron octahedron cube icosahedron and dodecahedron which have 4, 6, 8, 12, and 20 vertexes) and QKD protocol with continuous alphabet which corresponds to the limiting case of a polyhedron with infinitive number of vertexes are considered. Stability of such QKD protocols to the interceptresend and optimal eavesdropping strategies at the individual attacks is studied in detail. It is shown that in case of optimal eavesdropping strategy after safety bases reconciliation critical error rate of the QKD protocol with continuous alphabet surpasses all other protocols. Without basis reconciliation the highest critical error rate have the protocol with tetrahedron-type alphabet.
Long-distance behaviour of the surface-atom Casimir-Polder forces out of thermal equilibrium
International Nuclear Information System (INIS)
Long-distance behaviour of the Casimir-Polder-Lifshitz force between an atom and the surface of a substrate is investigated. When the temperatures of the substrate and the environment are different, the new decay law 1/z3 of the force at large distances is discovered, which is slower than at thermal equilibrium. The force is of a quantum nature and attractive or repulsive depending on whether the temperature of the substrate is higher or lower than that of the environment. A transparent derivation of this law is presented. It is based on a picture of evanescent waves, created in vacuum by the black-body radiation impinging on the surface near the angle of total reflection. Some new experimental possibilities of the measurement of the forces are discussed: oscillations of a Bose-Einstein condensate near the surface, Bloch oscillations of fermions in an optical lattice and phase evolution of a BEC in a double-well trap
Minimal Distances Between SCFTs
Buican, Matthew
2013-01-01
We study lower bounds on the minimal distance in theory space between four-dimensional superconformal field theories (SCFTs) connected via broad classes of renormalization group (RG) flows preserving various amounts of supersymmetry (SUSY). For N=1 RG flows, the ultraviolet (UV) and infrared (IR) endpoints of the flow can be parametrically close. On the other hand, for RG flows emanating from a maximally supersymmetric SCFT, the distance to the IR theory cannot be arbitrarily small regardless of the amount of (non-trivial) SUSY preserved along the flow. The case of RG flows from N=2 UV SCFTs is more subtle. We argue that for RG flows preserving the full N=2 SUSY, there are various obstructions to finding examples with parametrically close UV and IR endpoints. Under reasonable assumptions, these obstructions include: unitarity, known bounds on the c central charge derived from associativity of the operator product expansion, and the central charge bounds of Hofman and Maldacena. On the other hand, for RG flows...
Minimal distances between SCFTs
Buican, Matthew
2014-01-01
We study lower bounds on the minimal distance in theory space between four-dimensional superconformal field theories (SCFTs) connected via broad classes of renormalization group (RG) flows preserving various amounts of supersymmetry (SUSY). For = 1 RG flows, the ultraviolet (UV) and infrared (IR) endpoints of the flow can be parametrically close. On the other hand, for RG flows emanating from a maximally supersymmetric SCFT, the distance to the IR theory cannot be arbitrarily small regardless of the amount of (non-trivial) SUSY preserved along the flow. The case of RG flows from =2 UV SCFTs is more subtle. We argue that for RG flows preserving the full =2 SUSY, there are various obstructions to finding examples with parametrically close UV and IR endpoints. Under reasonable assumptions, these obstructions include: unitarity, known bounds on the c central charge derived from associativity of the operator product expansion, and the central charge bounds of Hofman and Maldacena. On the other hand, for RG flows that break = 2 → = 1, it is possible to find IR fixed points that are parametrically close to the UV ones. In this case, we argue that if the UV SCFT possesses a single stress tensor, then such RG flows excite of order all the degrees of freedom of the UV theory. Furthermore, if the UV theory has some flavor symmetry, we argue that the UV central charges should not be too large relative to certain parameters in the theory.
Minimal distances between SCFTs
Energy Technology Data Exchange (ETDEWEB)
Buican, Matthew [Department of Physics and Astronomy, Rutgers University,Piscataway, NJ 08854 (United States)
2014-01-28
We study lower bounds on the minimal distance in theory space between four-dimensional superconformal field theories (SCFTs) connected via broad classes of renormalization group (RG) flows preserving various amounts of supersymmetry (SUSY). For N=1 RG flows, the ultraviolet (UV) and infrared (IR) endpoints of the flow can be parametrically close. On the other hand, for RG flows emanating from a maximally supersymmetric SCFT, the distance to the IR theory cannot be arbitrarily small regardless of the amount of (non-trivial) SUSY preserved along the flow. The case of RG flows from N=2 UV SCFTs is more subtle. We argue that for RG flows preserving the full N=2 SUSY, there are various obstructions to finding examples with parametrically close UV and IR endpoints. Under reasonable assumptions, these obstructions include: unitarity, known bounds on the c central charge derived from associativity of the operator product expansion, and the central charge bounds of Hofman and Maldacena. On the other hand, for RG flows that break N=2→N=1, it is possible to find IR fixed points that are parametrically close to the UV ones. In this case, we argue that if the UV SCFT possesses a single stress tensor, then such RG flows excite of order all the degrees of freedom of the UV theory. Furthermore, if the UV theory has some flavor symmetry, we argue that the UV central charges should not be too large relative to certain parameters in the theory.
Distance collaborations with industry
Energy Technology Data Exchange (ETDEWEB)
Peskin, A.; Swyler, K.
1998-06-01
The college industry relationship has been identified as a key policy issue in Engineering Education. Collaborations between academic institutions and the industrial sector have a long history and a bright future. For Engineering and Engineering Technology programs in particular, industry has played a crucial role in many areas including advisement, financial support, and practical training of both faculty and students. Among the most important and intimate interactions are collaborative projects and formal cooperative education arrangements. Most recently, such collaborations have taken on a new dimension, as advances in technology have made possible meaningful technical collaboration at a distance. There are several obvious technology areas that have contributed significantly to this trend. Foremost is the ubiquitous presence of the Internet. Perhaps almost as important are advances in computer based imaging. Because visual images offer a compelling user experience, it affords greater knowledge transfer efficiency than other modes of delivery. Furthermore, the quality of the image appears to have a strongly correlated effect on insight. A good visualization facility offers both a means for communication and a shared information space for the subjects, which are among the essential features of both peer collaboration and distance learning.
Permutation-invariant distance between atomic configurations
International Nuclear Information System (INIS)
We present a permutation-invariant distance between atomic configurations, defined through a functional representation of atomic positions. This distance enables us to directly compare different atomic environments with an arbitrary number of particles, without going through a space of reduced dimensionality (i.e., fingerprints) as an intermediate step. Moreover, this distance is naturally invariant through permutations of atoms, avoiding the time consuming associated minimization required by other common criteria (like the root mean square distance). Finally, the invariance through global rotations is accounted for by a minimization procedure in the space of rotations solved by Monte Carlo simulated annealing. A formal framework is also introduced, showing that the distance we propose verifies the property of a metric on the space of atomic configurations. Two examples of applications are proposed. The first one consists in evaluating faithfulness of some fingerprints (or descriptors), i.e., their capacity to represent the structural information of a configuration. The second application concerns structural analysis, where our distance proves to be efficient in discriminating different local structures and even classifying their degree of similarity
Permutation-invariant distance between atomic configurations
Energy Technology Data Exchange (ETDEWEB)
Ferré, Grégoire; Maillet, Jean-Bernard [CEA, DAM, DIF, F-91297 Arpajon (France); Stoltz, Gabriel [Université Paris-Est, CERMICS (ENPC), INRIA, F-77455 Marne-la-Vallée (France)
2015-09-14
We present a permutation-invariant distance between atomic configurations, defined through a functional representation of atomic positions. This distance enables us to directly compare different atomic environments with an arbitrary number of particles, without going through a space of reduced dimensionality (i.e., fingerprints) as an intermediate step. Moreover, this distance is naturally invariant through permutations of atoms, avoiding the time consuming associated minimization required by other common criteria (like the root mean square distance). Finally, the invariance through global rotations is accounted for by a minimization procedure in the space of rotations solved by Monte Carlo simulated annealing. A formal framework is also introduced, showing that the distance we propose verifies the property of a metric on the space of atomic configurations. Two examples of applications are proposed. The first one consists in evaluating faithfulness of some fingerprints (or descriptors), i.e., their capacity to represent the structural information of a configuration. The second application concerns structural analysis, where our distance proves to be efficient in discriminating different local structures and even classifying their degree of similarity.
Transportation Distances on the Circle
Rabin, Julien; Gousseau, Yann
2009-01-01
In this contribution, we study Monge-Kantorovich distances between discrete set of points on the unit circle, when the ground distance between two points x and y on the circle is defined as the L1-shortest path. We first prove that computing a Monge-Kantorovich distance between two given sets of pairwise different points boils down to cut the circle at a well chosen point and to compute the same distance on the real line. This result is then used to prove a formula on the Earth Mover's Distance which is a particular Monge-Kantorovich distance. This formula asserts that the Earth Mover's Distance between two discrete circular normalized histograms can be computed from their cumulative histograms. This formula is used in recent papers on the matching of local features between images, where the Earth Mover's Distance is used to compare circular histograms of gradient orientations.
Pourbaix, D.; Arenou, F.; Halbwachs, J.-L.; Siopis, C.
2013-02-01
Gaia's five-year observation baseline might naively lead to the expectation that it will be possible to fit the parallax of any sufficiently nearby object with the default five-parameter model (position at a reference epoch, parallax and proper motion). However, simulated Gaia observations of a `model Universe' composed of nearly 107 objects, 50% of which turn out to be multiple stars, show that the single-star hypothesis can severely affect parallax estimation and that more sophisticated models must be adopted. In principle, screening these spurious single-star solutions is rather straightforward, for example by evaluating the quality of the fits. However, the simulated Gaia observations also reveal that some seemingly acceptable single-star solutions can nonetheless lead to erroneous distances. These solutions turn out to be binaries with an orbital period close to one year. Without auxiliary (e.g., spectroscopic) data, they will remain unnoticed.
Rybski, Diego; Kropp, Jürgen P
2012-01-01
Urban agglomerations exhibit complex emergent features of which Zipf's law, i.e. a power-law size distribution, and fractality may be regarded as the most prominent ones. We propose a simplistic model for the generation of city-like structures which is solely based on the assumption that growth is more likely to take place close to inhabited space. The model involves one parameter which is an exponent determining how strongly the attraction decays with the distance. In addition, the model is run iteratively so that existing clusters can grow and new ones can emerge. The model is capable of reproducing the size distribution and the fractality of the hull of the largest cluster. While the power-law distribution depends on both, the imposed exponent and the iteration, the fractality seems to be independent of the former and only depends on the latter.
Edit Distance for Pushdown Automata
Chatterjee, Krishnendu; Henzinger, Thomas A.; Ibsen-Jensen, Rasmus; Otop, Jan
2015-01-01
The edit distance between two words $w_1, w_2$ is the minimal number of word operations (letter insertions, deletions, and substitutions) necessary to transform $w_1$ to $w_2$. The edit distance generalizes to languages ${\\cal L}_1, {\\cal L}_2$, where the edit distance is the minimal number $k$ such that for every word from ${\\cal L}_1$ there exists a word in ${\\cal L}_2$ with edit distance at most $k$. We study the edit distance computation problem between pushdown automata and their subclas...
Planning with Reachable Distances
Tang, Xinyu
2009-01-01
Motion planning for spatially constrained robots is difficult due to additional constraints placed on the robot, such as closure constraints for closed chains or requirements on end effector placement for articulated linkages. It is usually computationally too expensive to apply sampling-based planners to these problems since it is difficult to generate valid configurations. We overcome this challenge by redefining the robot\\'s degrees of freedom and constraints into a new set of parameters, called reachable distance space (RD-space), in which all configurations lie in the set of constraint-satisfying subspaces. This enables us to directly sample the constrained subspaces with complexity linear in the robot\\'s number of degrees of freedom. In addition to supporting efficient sampling, we show that the RD-space formulation naturally supports planning, and in particular, we design a local planner suitable for use by sampling-based planners. We demonstrate the effectiveness and efficiency of our approach for several systems including closed chain planning with multiple loops, restricted end effector sampling, and on-line planning for drawing/sculpting. We can sample single-loop closed chain systems with 1000 links in time comparable to open chain sampling, and we can generate samples for 1000-link multi-loop systems of varying topology in less than a second. © 2009 Springer-Verlag.
Game theory of social distancing in response to an epidemic.
Directory of Open Access Journals (Sweden)
Timothy C Reluga
2010-05-01
Full Text Available Social distancing practices are changes in behavior that prevent disease transmission by reducing contact rates between susceptible individuals and infected individuals who may transmit the disease. Social distancing practices can reduce the severity of an epidemic, but the benefits of social distancing depend on the extent to which it is used by individuals. Individuals are sometimes reluctant to pay the costs inherent in social distancing, and this can limit its effectiveness as a control measure. This paper formulates a differential-game to identify how individuals would best use social distancing and related self-protective behaviors during an epidemic. The epidemic is described by a simple, well-mixed ordinary differential equation model. We use the differential game to study potential value of social distancing as a mitigation measure by calculating the equilibrium behaviors under a variety of cost-functions. Numerical methods are used to calculate the total costs of an epidemic under equilibrium behaviors as a function of the time to mass vaccination, following epidemic identification. The key parameters in the analysis are the basic reproduction number and the baseline efficiency of social distancing. The results show that social distancing is most beneficial to individuals for basic reproduction numbers around 2. In the absence of vaccination or other intervention measures, optimal social distancing never recovers more than 30% of the cost of infection. We also show how the window of opportunity for vaccine development lengthens as the efficiency of social distancing and detection improve.
Directory of Open Access Journals (Sweden)
César Roberto Goes Carqueija
1995-01-01
Full Text Available The occurence of Decapoda crustaceans in the diet of Dasyatis guttata (Bloch & Schneider, 1801 (Elasmobranchii. Dasyatididae is reported. Inferences are also made about some aspects of the predator - prey relationship in the area around the Ecological Station.
Stevo Stević
2008-01-01
We introduce an integral-type operator, denoted by PÃÂ†g, on the space of holomorphic functions on the unit ball BÃ¢ÂŠÂ‚Ã¢Â„Â‚n, which is an extension of the product of composition and integral operators on the unit disk. The operator norm of PÃÂ†g from the weighted Bergman space AÃŽÂ±p(B) to the Bloch-type space Ã¢Â„Â¬ÃŽÂ¼(B) or the little Bloch-type space Ã¢Â„Â¬ÃŽÂ¼,0(B) is calculated. The compactness of the operator is characterized in terms of inducing functions g and ÃÂ†. Upper and lower...
Sinkhorn Distances: Lightspeed Computation of Optimal Transportation Distances
Cuturi, Marco
2013-01-01
Optimal transportation distances are a fundamental family of parameterized distances for histograms. Despite their appealing theoretical properties, excellent performance in retrieval tasks and intuitive formulation, their computation involves the resolution of a linear program whose cost is prohibitive whenever the histograms' dimension exceeds a few hundreds. We propose in this work a new family of optimal transportation distances that look at transportation problems from a maximum-entropy ...
Hierarchical traits distances explain grassland Fabaceae species' ecological niches distances
Fort, Florian; Jouany, Claire; CRUZ, Pablo
2015-01-01
Fabaceae species play a key role in ecosystem functioning through their capacity to fix atmospheric nitrogen via their symbiosis with Rhizobium bacteria. To increase benefits of using Fabaceae in agricultural systems, it is necessary to find ways to evaluate species or genotypes having potential adaptations to sub-optimal growth conditions. We evaluated the relevance of phylogenetic distance, absolute trait distance and hierarchical trait distance for comparing the adaptation of 13 grassland ...
Perceptions and Actions of Distance Educators on Academic Procrastination.
Wilkinson, T. W.; Sherman, T. M.
1990-01-01
Describes study of distance educators that investigated academic procrastination in telecommunications-based distance education programs in higher education. Perceptions of the causes of academic procrastination are examined, data collection techniques on academic procrastination is discussed, strategies to reduce procrastination are described,…
Deconfounding Distance Effects in Judgments of Moral Obligation
Nagel, Jonas; Waldmann, Michael R.
2013-01-01
A heavily disputed question of moral philosophy is whether spatial distance between agent and victim is normatively relevant for the degree of obligation to help strangers in need. In this research, we focus on the associated descriptive question whether increased distance does in fact reduce individuals' sense of helping obligation. One problem…
Mohammed Safwan Ali Khan; Abdul Manan Mat Jais; Javeed Hussain; Faiza Siddiqua; Gopala Reddy, A.; P. Shivakumar; Madhuri, D.
2014-01-01
Channa striata (Bloch.) is a fresh water fish belonging to the family Channidae. The stripped snakehead fish possesses wide range of medicinal properties. In view of traditional use of C. striata for wound healing, the present study was undertaken to investigate the beneficial effects of orally administered freeze dried aqueous extract of Channa striata (AECS) in experimentally induced gastric ulcers in Wistar rats. Aspirin induced ulcerogenesis in pyloric ligation model was used for the asse...
Vankara, Anu Prasanna; Vijayalakshmi, C.
2009-01-01
A total of 9 metazoan parasitic species were identified from Mystus vittatus (Bloch) in river Godavari during 2005–2007 including 2 monogeneans, 2 digeneans, 3 acanthocephalans and 2 copepods. Two species of monogeneans (Bifurcohaptor indicus and Thaparocleidus tengra), digeneans (Haplorchoides macrones and metacercariae of Isoparorchis hypselobagri), an acanthocephalan (Raosentis podderi) found during the present study are of common occurrence in this fish. M. vittatus constitutes a new host...
Richter, Marten; Renger, Thomas; Knorr, Andreas
2008-01-01
On the basis of the recent progress in the resolution of the structure of the antenna light harvesting complex II (LHC II) of the photosystem II, we propose a microscopically motivated theory to predict excitation intensity-dependent spectra. We show that optical Bloch equations provide the means to include all 2( N ) excited states of an oligomer complex of N coupled two-level systems and analyze the effects of Pauli Blocking and exciton-exciton annihilation on pump-probe spectra. We use LHC Bloch equations for 14 Coulomb coupled two-level systems, which describe the S (0) and S (1) level of every chlorophyll molecule. All parameter introduced into the Hamiltonian are based on microscopic structure and a quantum chemical model. The derived Bloch equations describe not only linear absorption but also the intensity dependence of optical spectra in a regime where the interplay of Pauli Blocking effects as well as exciton-exciton annihilation effects are important. As an example, pump-probe spectra are discussed. The observed saturation of the spectra for high intensities can be viewed as a relaxation channel blockade on short time scales due to Pauli blocking. The theoretical investigation is useful for the interpretation of the experimental data, if the experimental conditions exceed the low intensity pump limit and effects like strong Pauli Blocking and exciton-exciton annihilation need to be considered. These effects become important when multiple excitations are generated by the pump pulse in the complex. PMID:17924202
Learning Stochastic Tree Edit Distance
Bernard, Marc; Habrard, Amaury; Sebban, Marc
2006-01-01
Trees provide a suited structural representation to deal with complex tasks such as web information extraction, RNA secondary structure prediction, or conversion of tree structured documents. In this context, many applications require the calculation of similarities between tree pairs. The most studied distance is likely the tree edit distance for which improvements in terms of complexity have been achieved during the last decade. However, this classic edit distance usually uses a priori fixe...
Edit Distance for Timed Automata
Chatterjee, Krishnendu; Ibsen-Jensen, Rasmus; Majumdar, Rupak
2013-01-01
The edit distance between two (untimed) traces is the minimum cost of a sequence of edit operations (insertion, deletion, or substitution) needed to transform one trace to the other. Edit distances have been extensively studied in the untimed setting, and form the basis for approximate matching of sequences in different domains such as coding theory, parsing, and speech recognition. In this paper, we lift the study of edit distances from untimed languages to the timed setting. We define ...
Edit Distance with Block Deletions
Dana Shapira; Storer, James A.
2011-01-01
Several variants of the edit distance problem with block deletions are considered. Polynomial time optimal algorithms are presented for the edit distance with block deletions allowing character insertions and character moves, but without block moves. We show that the edit distance with block moves and block deletions is NP-complete (Nondeterministic Polynomial time problems in which any given solution to such problem can be verified in polynomial time, and any NP problem can be converted into...
Mahalanobis' Distance Beyond Normal Distributions
Ekström, Joakim
2011-01-01
Based on the reasoning expressed by Mahalanobis in his original article, the present article extends the Mahalanobis distance beyond the set of normal distributions. Sufficient conditions for existence and uniqueness are studied, and some properties derived. Since many statistical methods use the Mahalanobis distance as e vehicle, e.g. the method of least squares and the chi-square hypothesis test, extending the Mahalanobis distance beyond normal distributions yields a high ratio of output to...
Are contemporary tourists consuming distance?
DEFF Research Database (Denmark)
Larsen, Gunvor Riber
of distance within the theoretical context of leisure mobility (question one) will be explored through the reading and discussion of literature concerned with concepts and theories that are using distance in their premises or as part of their argumentation. This will primarily be literature on mobility, space...... to elaborate constructions of other places; imaginations where distance is a fundamental factor differentiating between places in space. This is, however, by no means a complete list, and following this, a single definition of distance seems a futile exercise, where the benefit would be primarily analytical...
Keeping a healthy distance from senior management
van Houwelingen, Gijs
2015-01-01
markdownabstract__Abstract__ Follow the leader whilst showing a good example to your subordinates – such is the lot of the middle manager. This juggling of obligation and responsibility is made even more complicated when some of the decision-making at the top is deemed unfair. How do middle managers respond in such instances? Do they reproduce the unfair practices of their superiors or react against them? New research shows that creating physical distance from senior management reduces the ch...
Transactional Distance and Autonomy in a Distance Learning Environment
Vasiloudis, G.; Koutsouba, M.; Giossos, Y.; Mavroidis, I.
2015-01-01
This paper studies the transactional distance between the students and the tutor as well as the autonomy of students in a postgraduate course of the Hellenic Open University (HOU). The aim of the paper is to examine how the relation between autonomy and transactional distance evolves during an academic year and how this relation is affected by…
Directory of Open Access Journals (Sweden)
Javier Barrera-Chica
2009-12-01
Full Text Available Objetivo. Estudiar los hábitos alimentarios de la Mayupa (Sternopygus macrurus Bloch & Schneider, 1801 en el río Sinú, Colombia. Materiales y métodos. El contenido estomacal se evaluó con el coeficiente de vacuidad, grado de llenado, grado de digestión, frecuencia de ocurrencia, frecuencia numérica, gravimetría, indice de importancia relativa (IIR y la relación longitud intestinal (LI-longitud total (LT. Resultados. Solo pocos estómagos se encontraron vacíos (CV =6.9% y el 60.0% de las presas se encontraron frescas. Se identificaron cuatro ítems alimentarios: peces, crustáceos, material vegetal y otros. Peces fue el ítem más frecuente (76.9%, abundante (48.3%, con mayor composición por peso (81.9% y con mayor importancia relativa (63.2%. Conclusiones. Los resultados obtenidos permiten inferir que la Mayupa es un pez de hábitos alimentarios carnívoros, con preferencia por los peces.
Dynamics of the time dependent Bloch NMR equations for complex rFB1(t) magnetic field
International Nuclear Information System (INIS)
This study examines the dynamical changes produced by a complex time-dependent rFB1(t) magnetic field in an initially unperturbed magnetic resonance system. The analysis uses the Green's function algorithm as a tool to solve the transverse component of the time-dependent Bloch NMR equations with complex rFB1(t) field. The time development of the system is studied in the Hersenberg picture in which the operators are subject to unitary transformation as the applied rFB1(t) field changes the state of the NMR system from its initial ground state into another coherent state. The detailed features of the rFB1(t) field essentially affect the evolution of the state during its application. The state of the system after the complete cessation of the radio-frequency field is determined exclusively by a Fourier component which is in resonance with the NMR system. The unitary operator allows us to determine all the physically relevant information about the system in terms of a NMR relaxation parameter. (author)
Walker, Christopher M.; Bankson, James A.
2015-03-01
Magnetic resonance imaging (MRI) of hyperpolarized (HP) agents has the potential to probe in-vivo metabolism with sensitivity and specificity that was not previously possible. Biological conversion of HP agents specifically for cancer has been shown to correlate to presence of disease, stage and response to therapy. For such metabolic biomarkers derived from MRI of hyperpolarized agents to be clinically impactful, they need to be validated and well characterized. However, imaging of HP substrates is distinct from conventional MRI, due to the non-renewable nature of transient HP magnetization. Moreover, due to current practical limitations in generation and evolution of hyperpolarized agents, it is not feasible to fully experimentally characterize measurement and processing strategies. In this work we use a custom Bloch-McConnell simulator with pharmacokinetic modeling to characterize the performance of specific magnetic resonance spectroscopy sequences over a range of biological conditions. We performed numerical simulations to evaluate the effect of sequence parameters over a range of chemical conversion rates. Each simulation was analyzed repeatedly with the addition of noise in order to determine the accuracy and reproducibility of measurements. Results indicate that under both closed and perfused conditions, acquisition parameters can affect measurements in a tissue dependent manner, suggesting that great care needs to be taken when designing studies involving hyperpolarized agents. More modeling studies will be needed to determine what effect sequence parameters have on more advanced acquisitions and processing methods.
International Nuclear Information System (INIS)
The motion of the charged particle in a one-dimensional periodic potential of the Kronig-Penney type is considered. The energy band structure, Bloch wave functions (BWF) in coordinate and momentum representation are investigated in detail. Two sharply distinguished groups of states, i.e. below-the-barrier and above-the-barrier, are extracted, and the role of both positively and negatively charged particles in the channeling is explained. It is shown that only with use of a dispersion equation form one can obtain the information on the symmetry properties of the BWF at the edges of energy bands. The estimate of the corresponding regions of the edge coherence in the Brillouin zone is given. In above-the-barrier case the nontrivial effect of parity interchange violation of BWF at the edges of energy bands, connected with the nullification of the reflection coefficient either from the single barrier or well is found. Oscillation behaviour of both allowed and forbidden band widths is revealed. The analytical results for different values of the parameters are illustrated by computer calculations
Delamare-Deboutteville, J; Bowater, R; Condon, K; Reynolds, A; Fisk, A; Aviles, F; Barnes, A C
2015-12-01
Since 2007, 96 wild Queensland groupers, Epinephelus lanceolatus, (Bloch), have been found dead in NE Australia. In some cases, Streptococcus agalactiae (Group B Streptococcus, GBS) was isolated. At present, a GBS isolate from a wild grouper case was employed in experimental challenge trials in hatchery-reared Queensland grouper by different routes of exposure. Injection resulted in rapid development of clinical signs including bilateral exophthalmia, hyperaemic skin or fins and abnormal swimming. Death occurred in, and GBS was re-isolated from, 98% fish injected and was detected by PCR in brain, head kidney and spleen from all fish, regardless of challenge dose. Challenge by immersion resulted in lower morbidity with a clear dose response. Whilst infection was established via oral challenge by admixture with feed, no mortality occurred. Histology showed pathology consistent with GBS infection in organs examined from all injected fish, from fish challenged with medium and high doses by immersion, and from high-dose oral challenge. These experimental challenges demonstrated that GBS isolated from wild Queensland grouper reproduced disease in experimentally challenged fish and resulted in pathology that was consistent with that seen in wild Queensland grouper infected with S. agalactiae. PMID:25117665
Guan, Yue-Yang; Tian, Bo; Zhen, Hui-Lin; Wang, Yu-Feng; Chai, Jun
2016-03-01
In this article, the generalised nonlinear Schrödinger-Maxwell-Bloch system is investigated, which describes the propagation of the optical solitons in an optical fibre doped with two-level resonant impurities like erbium with the fourth-order dispersion taken into account. Bilinear forms are derived via the Hirota method, symbolic computation, and the auxiliary function. Bright solitons can be obtained for the complex envelope of the field and the measure of the polarisation for the resonant medium, while the dark ones have been deduced for the extant population inversion. Propagation of the one and two solitons is analysed with the results that the solitons keep their shapes unchanged after the interaction, except for the phase shifts, which means that the interaction is elastic. Velocities of the solitons decrease when the effect of discreteness and higher-order dispersion increases. For the bound-state solitons, which can be formed among the solitons at the same velocity, the period decreases when the effect of discreteness and higher-order dispersion increases.
Chen, Wen-Jun; Ma, Hong; Yu, De; Zeng, Xiao-Hu
2016-08-01
A novel nuclear magnetic resonance (NMR) experimental scheme, called wideband continuous wave NMR (WB-CW-NMR), is presented in this article. This experimental scheme has promising applications in pulsed magnetic fields, and can dramatically improve the utilization of the pulsed field. The feasibility of WB-CW-NMR scheme is verified by numerically solving modified Bloch equations. In the numerical simulation, the applied magnetic field is a pulsed magnetic field up to 80 T, and the wideband continuous radio frequency (RF) excitation is a band-limited (0.68–3.40 GHz) white noise. Furthermore, the influences of some experimental parameters, such as relaxation time, applied magnetic field strength and wideband continuous RF power, on the WB-CW-NMR signal are analyzed briefly. Finally, a multi-channel system framework for transmitting and receiving ultra wideband signals is proposed, and the basic requirements of this experimental system are discussed. Meanwhile, the amplitude of the NMR signal, the level of noise and RF interference in WB-CW-NMR experiments are estimated, and a preliminary adaptive cancellation plan is given for detecting WB-CW-NMR signal from large background interference. Supported by National Natural Science Foundation of China (11475067), the Innovative Research Foundation of Huazhong University of Science and Technology (2015 ZDTD017) and the Experimental Apparatus Research Project of Wuhan Pulsed High Magnetic Field Center (2015KF17)
Higher Order Radial Derivatives of Bloch Type Functions%Bloch型函数的高阶径向导数
Institute of Scientific and Technical Information of China (English)
卓文新
2002-01-01
讨论了复超球上全纯函数的高阶导数的增长速度,证明了f∈Bα的充分必要条件是supa∈B(1-|z|2)m+α-1|Rmf(z)|＜∞,或supa∈B∫B(1-|z|2)(m+α-1)|Rmf(z)|pJRφα(z)dv(z)＜∞,或(1-|z|2)p(m+α-1)|Rmf(z)|pdv(z)是Bergman-Carleson测度.%In this paper, higher order radial derivatives of Bloch type functions in the unit ball of Cn is discussed and it is proved that for f∈H(B), f∈Bα if and only if supα∈B(1-|z|2)m+α-1|Rmf(z)|＜∞, if and only if supa∈B∫B(1-|z|2)P(m+α-1)|Rmf(z)|PJRφα(z)dv(z)＜∞, if and only if (1-|z|2)P(m+α-1)|Rmf(z)|Pdv(z) is a Bergman-Carleson measure.
International Nuclear Information System (INIS)
Recent measurements of the stopping powers of polysulfone for 0.66-1.74 MeV protons and 1.04-3.20 MeV alpha particles have been analyzed in terms of the modified Bethe-Bloch theory in order to extract values of the parameters characterizing the formalism utilized. Resulting values of mean excitation energy (I) and Barkas-effect parameter (b), respectively, were 83.3 eV and 1.05 for proton data, and 81.1 eV and 1.38 for alpha particle data. The lower energy alpha particle data were included by employing a single effective charge parameter (λ) evaluated at 1.63. The composite weighted value of mean excitation energy, 82.9 eV, lies some 6% above the additivity-based estimate, whereas the corresponding value of Barkas-effect parameter, 1.22, agrees quite well with the prescribed interval of 1.4±0.1
Directory of Open Access Journals (Sweden)
Bogdan Mihai Udroiu
2015-12-01
Full Text Available The main objective of this study is to see how the metylthiophanate fungicide influences the energetic metabolism and the breathing rhythm at Carassius auratus gibelio Bloch L. 1758. Experimental samples were subjected to under-lethal concentrations of 3.75mg/l, 7.5mg/l, 15mg/l and 30mg/l methyl-thiophanate fungicide from 24 to 336 hours. The physiologic parameter with the highest growth rate was the oxygen consumption, which, at the concentration of 7.5mg/l grew by 40.3% in 6 hours, compared to the witness values, registering the value of 179.52 mg oxygen/l/h compared to 127.95 mg oxygen/l/h. Also, the breathing rhythm grew at the concentration of 7.5 mg/l by 24.76% in 6 hours, compared to the witness values. At the concentration of 30mg/l, both physiologic parameters decreased. So, after 6 hours, the oxygen consumption decrease up to 31.38% from the witness values, registering the value of 51.503mg oxygen/l/h compared to 164.09mg oxygen/l/h, and the breathing rhythm decreased to 84.3% compared to the witness martor.
Frazier, Michael J.; Hussein, Mahmoud I.
2016-05-01
It is common for dispersion curves of damped periodic materials to be based on real frequencies as a function of complex wavenumbers or, conversely, real wavenumbers as a function of complex frequencies. The former condition corresponds to harmonic wave motion where a driving frequency is prescribed and where attenuation due to dissipation takes place only in space alongside spatial attenuation due to Bragg scattering. The latter condition, on the other hand, relates to free wave motion admitting attenuation due to energy loss only in time while spatial attenuation due to Bragg scattering also takes place. Here, we develop an algorithm for 1D systems that provides dispersion curves for damped free wave motion based on frequencies and wavenumbers that are permitted to be simultaneously complex. This represents a generalized application of Bloch's theorem and produces a dispersion band structure that fully describes all attenuation mechanisms, in space and in time. The algorithm is applied to a viscously damped mass-in-mass metamaterial exhibiting local resonance. A frequency-dependent effective mass for this damped infinite chain is also obtained. xml:lang="fr"
Directory of Open Access Journals (Sweden)
Dergam Jorge A.
2002-01-01
Full Text Available In the Rio Doce basin of southeastern Brazil, the freshwater fish Hoplias malabaricus (trahira is a widespread predatory characin and one of the few resilient native fishes in a highly impacted lake system. In order to test for genetic differentiation in populations within this basin and for biogeographic relationships among populations of this species in other basins, a study was conducted using RAPD-PCR analysis of Rio Doce samples (N = 63 and phylogeographic analyses with mitochondrial DNA (mtDNA haplotypes, including the Rio Grande and Macacu river basins. In the Rio Doce basin, the patterns of genetic similarity of RAPD-PCR markers (individual fingerprinting and Nei?s genetic distance suggest the existence of two genetically different groups, one composed of the lacustrine populations Carioca and Dom Helvécio, and the other of riverine and the remaining lacustrine populations. The differences in the RAPD-PCR patterns may be explained by the existence of sub-basins within this lacustrine system. A maximum parsimony tree of cytochrome b fragment (383 base pairs supports the view that trahiras of the Rio Doce share a complex biogeographic history with those of neighboring basins. The phylogeographic patterns may be explained by a common history of the watersheds of the Rio Doce, Paraíba do Sul, and Rio Grande basins, corroborating the hypothesis of a Plio-Pleistocene separation of these drainage systems, forming the Mantiqueira "divortium aquarium".
Distance Education and the WWW
Peraya, Daniel
1995-01-01
Examines the evolution of distance education and learning via the use of communication technology. Focuses on distance education as a way of preparing returning adult students to meet demands of the labor market, and reviews uses of the World Wide Web as a communication tool to create electronic classrooms and deliver instructional materials.
"Distance Education", 2000-2010
Oviatt, Darin; Burdis, Jacob; West, Richard E.
2012-01-01
This article analyzes the articles published in the journal "Distance Education" from 2000-2010. The researchers analyzed these articles to determine the primary topics, research methods, key phrases in article titles, authorship, and most highly cited pieces. The development of new approaches to engage in distance education is a recurring theme…
Faculty Attitudes about Distance Education
Smidt, Esther; McDyre, Brian; Bunk, Jennifer; Li, Rui; Gatenby, Tanya
2014-01-01
In recent years, there has been a dramatic increase in distance learning in higher education. Given this, it is extremely important to understand faculty attitudes about distance education, not only because they can vary widely, but also because it is the faculty, through their design and implementation of online courses, that will shape the…
Distance transforms: academics versus industry
Broek, van den Egon L.; Schouten, Th.E.
2011-01-01
In image and video analysis, distance transformations (DT) are frequently used. They provide a distance image (DI) of background pixels to the nearest object pixel. DT touches upon the core of many applications; consequently, not only science but also industry has conducted a significant body of wor
Virtual Bioinformatics Distance Learning Suite
Tolvanen, Martti; Vihinen, Mauno
2004-01-01
Distance learning as a computer-aided concept allows students to take courses from anywhere at any time. In bioinformatics, computers are needed to collect, store, process, and analyze massive amounts of biological and biomedical data. We have applied the concept of distance learning in virtual bioinformatics to provide university course material…
Determining distances using asteroseismic methods
DEFF Research Database (Denmark)
Aguirre, Victor Silva; Casagrande, L.; Basu, Sarbina;
2013-01-01
fluxes, and thus distances for field stars in a self-consistent manner. Applying our method to a sample of solar-like oscillators in the {\\it Kepler} field that have accurate {\\it Hipparcos} parallaxes, we find agreement in our distance determinations to better than 5%. Comparison with measurements of...
Distance Education: Educational Trajectory Control
Isaev, Andrey; Kravets, Alla; Isaeva, Ludmila; Fomenkov, Sergey
2013-01-01
Distance education has become a rather popular form of education recently. The advantages of this form are obvious and well-known. They include asynchronous learning, individualized learning trajectories and convenient case technologies. However, the distance form of education is not able to form the trainee's hands-on experience, especially…
The Psychology of Psychic Distance
DEFF Research Database (Denmark)
Håkanson, Lars; Ambos, Björn; Schuster, Anja;
2016-01-01
and their theoretical underpinnings assume psychic distances to be symmetric. Building on insights from psychology and sociology, this paper demonstrates how national factors and cognitive processes interact in the formation of asymmetric distance perceptions. The results suggest that exposure to other countries...
Map Edit Distance vs Graph Edit Distance for Matching Images
Combier, Camille; Damiand, Guillaume; Solnon, Christine
2013-01-01
Generalized maps are widely used to model the topology of nD objects (such as 2D or 3D images) by means of incidence and adjacency relationships between cells (0D vertices, 1D edges, 2D faces, 3D volumes, ...). Recently, we have introduced a map edit distance. This distance compares maps by means of a minimum cost sequence of edit operations that should be performed to transform a map into another map. In this paper, we introduce labelled maps and we show how the map edit distance may be exte...
Gd(III)-Gd(III) distance measurements with chirp pump pulses
Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar
2015-10-01
The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S = 7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero
The Distance Field Model and Distance Constrained MAP Adaptation Algorithm
Institute of Scientific and Technical Information of China (English)
YUPeng; WANGZuoying
2003-01-01
Spatial structure information, i.e., the rel-ative position information of phonetic states in the feature space, is long to be carefully researched yet. In this pa-per, a new model named “Distance Field” is proposed to describe the spatial structure information. Based on this model, a modified MAP adaptation algorithm named dis-tance constrained maximum a poateriori (DCMAP) is in-troduced. The distance field model gives large penalty when the spatial structure is destroyed. As a result the DCMAP reserves the spatial structure information in adaptation process. Experiments show the Distance Field Model improves the performance of MAP adapta-tion. Further results show DCMAP has strong cross-state estimation ability, which is used to train a well-performed speaker-dependent model by data from only part of pho-
Language distance and tree reconstruction
Petroni, Filippo; Serva, Maurizio
2008-08-01
Languages evolve over time according to a process in which reproduction, mutation and extinction are all possible. This is very similar to haploid evolution for asexual organisms and for the mitochondrial DNA of complex ones. Exploiting this similarity, it is possible, in principle, to verify hypotheses concerning the relationship among languages and to reconstruct their family tree. The key point is the definition of the distances among pairs of languages in analogy with the genetic distances among pairs of organisms. Distances can be evaluated by comparing grammar and/or vocabulary, but while it is difficult, if not impossible, to quantify grammar distance, it is possible to measure a distance from vocabulary differences. The method used by glottochronology computes distances from the percentage of shared 'cognates', which are words with a common historical origin. The weak point of this method is that subjective judgment plays a significant role. Here we define the distance of two languages by considering a renormalized edit distance among words with the same meaning and averaging over the two hundred words contained in a Swadesh list. In our approach the vocabulary of a language is the analogue of DNA for organisms. The advantage is that we avoid subjectivity and, furthermore, reproducibility of results is guaranteed. We apply our method to the Indo-European and the Austronesian groups, considering, in both cases, fifty different languages. The two trees obtained are, in many respects, similar to those found by glottochronologists, with some important differences as regards the positions of a few languages. In order to support these different results we separately analyze the structure of the distances of these languages with respect to all the others.
Language distance and tree reconstruction
International Nuclear Information System (INIS)
Languages evolve over time according to a process in which reproduction, mutation and extinction are all possible. This is very similar to haploid evolution for asexual organisms and for the mitochondrial DNA of complex ones. Exploiting this similarity, it is possible, in principle, to verify hypotheses concerning the relationship among languages and to reconstruct their family tree. The key point is the definition of the distances among pairs of languages in analogy with the genetic distances among pairs of organisms. Distances can be evaluated by comparing grammar and/or vocabulary, but while it is difficult, if not impossible, to quantify grammar distance, it is possible to measure a distance from vocabulary differences. The method used by glottochronology computes distances from the percentage of shared 'cognates', which are words with a common historical origin. The weak point of this method is that subjective judgment plays a significant role. Here we define the distance of two languages by considering a renormalized edit distance among words with the same meaning and averaging over the two hundred words contained in a Swadesh list. In our approach the vocabulary of a language is the analogue of DNA for organisms. The advantage is that we avoid subjectivity and, furthermore, reproducibility of results is guaranteed. We apply our method to the Indo-European and the Austronesian groups, considering, in both cases, fifty different languages. The two trees obtained are, in many respects, similar to those found by glottochronologists, with some important differences as regards the positions of a few languages. In order to support these different results we separately analyze the structure of the distances of these languages with respect to all the others
Spherical Location Under Restricted Distance
Directory of Open Access Journals (Sweden)
U. R. Dhar
1986-07-01
Full Text Available This paper deals with the problem of locating a new facility with respect to n given demand points on earth, with upper bounds imposed on distances between the new facility and each demand points. Distances are measured as the length of the shortest arc of great circle. The proposed algorithm makes use of a Lagrangean relaxation in which the distance constraints, which are not satisfied by the associated unconstrained solution, are incorporated in the economic function. Computational results of a limited number of test problems are presented.
Long working distance incoherent interference microscope
Sinclair, Michael B.; De Boer, Maarten P.
2006-04-25
A full-field imaging, long working distance, incoherent interference microscope suitable for three-dimensional imaging and metrology of MEMS devices and test structures on a standard microelectronics probe station. A long working distance greater than 10 mm allows standard probes or probe cards to be used. This enables nanometer-scale 3-dimensional height profiles of MEMS test structures to be acquired across an entire wafer while being actively probed, and, optionally, through a transparent window. An optically identical pair of sample and reference arm objectives is not required, which reduces the overall system cost, and also the cost and time required to change sample magnifications. Using a LED source, high magnification (e.g., 50.times.) can be obtained having excellent image quality, straight fringes, and high fringe contrast.
Study of speed endurance middle distance runners
Directory of Open Access Journals (Sweden)
Golovaschenko R.V.
2013-12-01
Full Text Available Purpose : To investigate the boost performance speed endurance runners who specialize in middle-distance running . Material and methods : The study involved team members Vinnytsia region in an amount of 44 people, whose average age was 20,2 ± 2,1 years. Classes are held during the 21-day mesocycle, 5 times a week, twice a day. Things were aimed at enhancing the development of indicators of special speed endurance. Results : The dynamics of the running speed of the model segments that characterize speed endurance athletes. Proved that the improved running 400 meter intervals helps reduce travel time competitive distance of 1500 meters. Conclusion : The use of the program contributes to higher speed endurance, which determines the result in the women's 1,500 meters.
ECONOMICS OF DISTANCE EDUCATION RECONSIDERED
Directory of Open Access Journals (Sweden)
Wolfram LAASER
2008-07-01
Full Text Available ABSTRACT According to Gartner a certain hype of e-Learning was followed by a downturn but eLearning will continue to be an important factor in learning scenarios. However the economic viability of e-learning projects will be questioned with more scrutiny than in earlier periods. Therefore it seems to be a good opportunity to see what can be learned from past experience in costing distance learning projects and what aspects are added by current attempts to measure economic efficiency. After reviewing early research about costing distance learning some more recent approaches will be discussed, such as eLearning ROI-calculators and the concept of total cost of ownership. Furthermore some microeconomic effects referring to localization of distance learning courses are outlined. Finally several unsolved issues in costing distance education are summarized.
Sormani, Christina
2015-01-01
Given a time function $\\tau$ on a spacetime $M$, we define a `null distance function', $\\hat{d}_\\tau$, built from and closely related to the causal structure of $M$. In basic models with timelike $\
Distance Learning for Special Populations
Bates, Rodger A.
2012-01-01
Distance education strategies for remotely deployed, highly mobile, or institutionalized populations are reviewed and critiqued. Specifically, asynchronous, offline responses for special military units, Native Americans on remote reservations, prison populations and other geographically, temporally or technologically isolated niche populations are…
Opportunity Cost of Distance Education
Turkoglu, Recep
2004-01-01
In this study, opportunity cost (OC) of distance education (DE) has been examined. In addition, factors which affect OC of DE have been investigated. (Contains 1 table.) [Abstract modified to meet ERIC guidelines.
Distance Education in Technological Age
Directory of Open Access Journals (Sweden)
R .C. SHARMA
2005-04-01
Full Text Available Distance Education in Technological AgeRomesh Verma (Editor, New Delhi: Anmol Publications, 2005, ISBN 81-261-2210-2, pp. 419 Reviewed by R C SHARMARegional DirectorIndira Gandhi National Open University-INDIA The advancements in information and communication technologies have brought significant changes in the way the open and distance learning are provided to the learners. The impact of such changes is quite visible in both developed and developing countries. Switching over to online mode, joining hands with private initiatives and making a presence in foreign waters, are some of the hallmarks of the open and distance education (ODE institutions in developing countries. The compilation of twenty six essays on themes as applicable to ODE has resulted in the book, Distance Education in Technological Age. These essays follow a progressive style of narration, starting from describing conceptual framework of distance education, how the distance education was emerged on the global scene and in India, and then goes on to discuss emergence of online distance education and research aspects in ODE. The initial four chapters provide a detailed account of historical development and growth of distance education in India and State Open University and National Open University Model in India . Student support services are pivot to any distance education and much of its success depends on how well the support services are provided. These are discussed from national and international perspective. The issues of collaborative learning, learning on demand, life long learning, learning-unlearning and re-learning model and strategic alliances have also given due space by the authors. An assortment of technologies like communication technology, domestic technology, information technology, mass media and entertainment technology, media technology and educational technology give an idea of how these technologies are being adopted in the open universities. The study
KNOWLEDGE DISTANCE IN INFORMATION SYSTEMS
Institute of Scientific and Technical Information of China (English)
Yuhua QIAN; Jiye LIANG; Chuangyin DANG; Feng WANG; Wei XU
2007-01-01
In this paper, we first introduce the concepts of knowledge closeness and knowledge distance for measuring the sameness and the difference among knowledge in an information system, respectively.The relationship between these two concepts is a strictly mutual complement relation. We then investigate some important properties of knowledge distance and perform experimental analyses on two public data sets, which show the presented measure appears to be well suited to characterize the nature of knowledge in an information system. Finally, we establish the relationship between the knowledge distance and knowledge granulation, which shows that two variants of the knowledge distance can also be used to construct the knowledge granulation. These results will be helpful for studying uncertainty in information systems.
Some Remarks on Diffusion Distances
Directory of Open Access Journals (Sweden)
Maxim J. Goldberg
2010-01-01
Full Text Available As a diffusion distance, we propose to use a metric (closely related to cosine similarity which is defined as the 2 distance between two 2-normalized vectors. We provide a mathematical explanation as to why the normalization makes diffusion distances more meaningful. Our proposal is in contrast to that made some years ago by R. Coifman which finds the 2 distance between certain 1 unit vectors. In the second part of the paper, we give two proofs that an extension of mean first passage time to mean first passage cost satisfies the triangle inequality; we do not assume that the underlying Markov matrix is diagonalizable. We conclude by exhibiting an interesting connection between the (normalized mean first passage time and the discretized solution of a certain Dirichlet-Poisson problem and verify our result numerically for the simple case of the unit circle.
Distance Dependent Chinese Restaurant Processes
Blei, David M.; Frazier, Peter I.
2009-01-01
We develop the distance dependent Chinese restaurant process (CRP), a flexible class of distributions over partitions that allows for non-exchangeability. This class can be used to model many kinds of dependencies between data in infinite clustering models, including dependencies across time or space. We examine the properties of the distance dependent CRP, discuss its connections to Bayesian nonparametric mixture models, and derive a Gibbs sampler for both observed and mixture settings. We s...
Approaching intonational distance and change
Sullivan, Jennifer Niamh
2011-01-01
The main aim of this thesis is to begin to extend phonetic distance measurements to the domain of intonation. Existing studies of segmental phonetic distance have strong associations with historical linguistic questions. I begin with this context and demonstrate problems with the use of feature systems in these segmental measures. Then I attempt to draw strands from the disparate fields of quantitative historical linguistics and intonation together. The intonation of Belfast...
Real Laboratories for Distance Education
McCracken, Stuart; Zilic, Zeljko; Chan, Henry
2003-01-01
Providing distance laboratory-based courses is becoming critical for distance technical education. In this work, we describe remote laboratories in digital system courses. While the hardware is based on widely used programmable logic, the Internet interfaces include those for remote development, testing and debugging as well as the cooperative work environment. Special attention has been paid to the objectivity of evaluating the remote cooperative work. The web tools for project progress eval...
Distance Education in Technological Age
Sharma, R.C.
2005-01-01
Distance Education in Technological AgeRomesh Verma (Editor), New Delhi: Anmol Publications, 2005, ISBN 81-261-2210-2, pp. 419 Reviewed by R C SHARMARegional DirectorIndira Gandhi National Open University-INDIA The advancements in information and communication technologies have brought significant changes in the way the open and distance learning are provided to the learners. The impact of such changes is quite visible in both developed and developing countries. Switching over to online mode...
International Nuclear Information System (INIS)
The long-term toxic effects of continuous exposure for 6 months, from January to June, to a safe dose (4.5 ppm) of a commercial carbamate pesticide, carbofuran, on the histophysiology of thyroid in adult and young (yearling) Channa punctatus, are described in this investigation. In both the experimental groups, thyroid histology exhibited various abnormalities, including hypertrophy, hyperplasia and degeneration of follicular epithelial cells, and reduction in colloid content. Apart from this, in young experimentals, fibrosis of thyroid components, formation of cystic cellular masses, and rupture of blood vessels resulting in hemorrhage can also be seen and suggest direct action of this pesticide on the thyroid. On the other hand, in both treated groups, retardation of thyroid function was also evidenced by significantly reduced thyroidal radioiodine (131I) uptake and CR (conversion ratio of PB131I in blood serum in relation to total serum 131I uptake) values. Apparently, these histopathological and physiological changes were markedly pronounced in young experimentals, suggesting greater susceptibility of this group to chronic toxicity of carbofuran than that of adults. Thus, on the basis of these results, it can be inferred that carbofuran pesticide, which is washed into water systems in small quantities, induces adverse histophysiological alterations in thyroid, in an age- and size-dependent manner, possibly by acting directly on thyroid and/or through the hypothalamo-pituitary-thyroid axis, in this species
Prendergast, David; Louie, Steven G.
2009-12-01
We present an efficient generalization of the k -space interpolation scheme for electronic structure presented by Shirley [Phys. Rev. B 54, 16464 (1996)]. The method permits the construction of a compact k -dependent Hamiltonian using a numerically optimal basis derived from a coarse-grained set of effective single-particle electronic-structure calculations (based on density-functional theory in this work). We provide some generalizations of the initial approach which reduce the number of required initial electronic-structure calculations, enabling accurate interpolation over the entire Brillouin zone based on calculations at the zone center only for large systems. We also generalize the representation of nonlocal Hamiltonians, leading to a more efficient implementation which permits the use of both norm-conserving and ultrasoft pseudopotentials in the input calculations. Numerically interpolated electronic eigenvalues with accuracy that is within 0.01 eV can be produced at very little computational cost. Furthermore, accurate eigenfunctions—expressed in the optimal basis—provide easy access to useful matrix elements for simulating spectroscopy and we provide details for computing optical transition amplitudes. The approach is also applicable to other theoretical frameworks such as the Dyson equation for quasiparticle excitations or the Bethe-Salpeter equation for optical responses.
Prendergast, David; Louie, Steven G.
2010-03-01
We present an efficient generalization of the k-space interpolation scheme for electronic structure presented by E. L. Shirley, Phys. Rev. B 54, 16464 (1996), which permits the construction of a compact k-dependent Hamiltonian using a numerically optimal basis derived from a coarse-grained set of density functional theory calculations. We provide some generalizations of the initial approach which reduce the number of required initial electronic structure calculations, enabling accurate interpolation over the entire Brillouin zone based on calculations at the zone-center only for large systems. We also generalize the representation of non-local Hamiltonians, leading to a more efficient implementation which permits the use of both norm-conserving and ultrasoft pseudopotentials in the input calculations. Numerically interpolated electronic eigenvalues with accuracy that is within 0.01 eV can be produced at very little computational cost. The approach is also applicable to other theoretical frameworks such as the Dyson equation for quasiparticle excitations or the Bethe-Salpeter equation for optical responses.
Cultivar and row distance interactions in perennial ryegrass
DEFF Research Database (Denmark)
Deleuran, Lise C; Gislum, René; Boelt, Birte
2009-01-01
was not affected in the first-year seed production in three perennial ryegrass cultivars. Regardless of row distance the seed rate was 6 kg ha-1 and hence in-row plant density in autumn and spring was higher at 48 compared with 12 cm; however, in all three cultivars the highest number of reproductive...... tillers was recorded at 12-cm row distance. Row distance affected seed yields of only the diploid amenity cultivar 'Allegro', where a row distance of 48 cm reduced the seed yield compared with 12- and 24-cm row distance. When data from the three cultivars were merged there was a positive correlation...... between the seed yield and seed weight (r=0.72***), whereas the correlation between seed yield and the number of reproductive tillers was negatively correlated (r= - 0.49***). This may reflect choice of cultivars in the experiment with the tetraploid forage cultivar 'Tivoli' having the lowest number of...
La conciencia de la libertad (La filosofía moral como filosofía de la historia en Ernst Bloch)
Gimbernat, José Antonio
1991-01-01
Not available.
A partir del concepto hegeliano de «progreso en la conciencia de la libertad », se puede hacer una lectura de la filosofía moral de Bloch como filosofía de la historia. Ello conduce a una reino reinterpretación libre y materialista de Hegel y a una recuperación de la moral en el marxismo. En diálogo con Kant se hace posible descubrir el potencial utópico del énfasis subjetivo de la moral. El objetivo del reino de la libertad marxiano es la clave de una histor...
方波电场驱动下的Rabi振荡%Rabi Oscillations Between Bloch Bands in a Square-wave Electric Field
Institute of Scientific and Technical Information of China (English)
宫建平; 邵建立; 段素青; 赵宪庚
2006-01-01
We investigate double Bloch bands driven by a square-wave electric field with a tight-binding model. Using Fourier analysis, we analytically obtain resonance conditions of Rabi oscillation and Rabi frequency in the weak-coupling limit. The results are verified by numerical evolution of electrons.%研究了方波电场驱动下的双Bloch带的紧束缚模型.借助Fourier分析,得到了在弱耦合极限下Rabi振荡及Rabi频率的解析解;这些结果均由电子的数值演化所证实.
Vankara, Anu Prasanna; Vijayalakshmi, C
2009-12-01
A total of 9 metazoan parasitic species were identified from Mystus vittatus (Bloch) in river Godavari during 2005-2007 including 2 monogeneans, 2 digeneans, 3 acanthocephalans and 2 copepods. Two species of monogeneans (Bifurcohaptor indicus and Thaparocleidus tengra), digeneans (Haplorchoides macrones and metacercariae of Isoparorchis hypselobagri), an acanthocephalan (Raosentis podderi) found during the present study are of common occurrence in this fish. M. vittatus constitutes a new host record for an acanthocephalan, Raosentis thapari and 2 copepods, Argulus striatus and Lamproglena hospetensis. The occurrence of A. striatus represents unusual for M. vittatus. A new species of acanthocephala, Raosentis godavarensis sp. nov is reported, described and illustrated. PMID:23129893
Robillart, B.; Maynard, G.; Cros, B.; Boudaa, A.; Dubau, J.; Sebban, S.; Goddet, JP.
It has been recently demonstrated experimentally that seeding a high-harmonic pulse into an Optical-Field-Ionized gas can generate a coherent soft x-ray laser beam of up to 1üJ. In order to analyze the physical processes involved in the amplification of the x-ray laser pulse through the plasma amplifier a 3D numerical code named COFIXE_MB has been developed using a Maxwell-Bloch treatment. It brings detailed information about the x-ray pulse evolution, especially regarding the fast evolution of the pulse temporal profile and the spatial filtering of the wave front structure by the amplifier.
Center—Distance Continuous Probability Models and the Distance Measure
Institute of Scientific and Technical Information of China (English)
郑方; 吴文虎; 等
1998-01-01
In this paper,a new statistic model named Center-Distance Continuous Probability Model(CDCPM)for speech recognition is described,which is based on Center-Distance Normal(CDN)distribution.In a CDCPM,the probability transition matrix is omitted,and the observation probability density function(PDF)in each state is in the form of embedded multiple-model(EMM)based on the Nearest Neighbour rule.The experimental results on two giant real-world Chinese speech databases and a real-world continuous-manner 2000 phrase system show that this model is a powerful one.Also,a distance measure for CDPMs is proposed which is based on the Bayesian minimum classification error(MCE) discrimination.
Distance sampling methods and applications
Buckland, S T; Marques, T A; Oedekoven, C S
2015-01-01
In this book, the authors cover the basic methods and advances within distance sampling that are most valuable to practitioners and in ecology more broadly. This is the fourth book dedicated to distance sampling. In the decade since the last book published, there have been a number of new developments. The intervening years have also shown which advances are of most use. This self-contained book covers topics from the previous publications, while also including recent developments in method, software and application. Distance sampling refers to a suite of methods, including line and point transect sampling, in which animal density or abundance is estimated from a sample of distances to detected individuals. The book illustrates these methods through case studies; data sets and computer code are supplied to readers through the book’s accompanying website. Some of the case studies use the software Distance, while others use R code. The book is in three parts. The first part addresses basic methods, the ...
Sensor Localization from Distance and Orientation Constraints.
Porta, Josep M; Rull, Aleix; Thomas, Federico
2016-01-01
The sensor localization problem can be formalized using distance and orientation constraints, typically in 3D. Local methods can be used to refine an initial location estimation, but in many cases such estimation is not available and a method able to determine all the feasible solutions from scratch is necessary. Unfortunately, existing methods able to find all the solutions in distance space can not take into account orientations, or they can only deal with one- or two-dimensional problems and their extension to 3D is troublesome. This paper presents a method that addresses these issues. The proposed approach iteratively projects the problem to decrease its dimension, then reduces the ranges of the variable distances, and back-projects the result to the original dimension, to obtain a tighter approximation of the feasible sensor locations. This paper extends previous works introducing accurate range reduction procedures which effectively integrate the orientation constraints. The mutual localization of a fleet of robots carrying sensors and the position analysis of a sensor moved by a parallel manipulator are used to validate the approach. PMID:27428977
Sensor Localization from Distance and Orientation Constraints
Porta, Josep M.; Rull, Aleix; Thomas, Federico
2016-01-01
The sensor localization problem can be formalized using distance and orientation constraints, typically in 3D. Local methods can be used to refine an initial location estimation, but in many cases such estimation is not available and a method able to determine all the feasible solutions from scratch is necessary. Unfortunately, existing methods able to find all the solutions in distance space can not take into account orientations, or they can only deal with one- or two-dimensional problems and their extension to 3D is troublesome. This paper presents a method that addresses these issues. The proposed approach iteratively projects the problem to decrease its dimension, then reduces the ranges of the variable distances, and back-projects the result to the original dimension, to obtain a tighter approximation of the feasible sensor locations. This paper extends previous works introducing accurate range reduction procedures which effectively integrate the orientation constraints. The mutual localization of a fleet of robots carrying sensors and the position analysis of a sensor moved by a parallel manipulator are used to validate the approach. PMID:27428977
Setting the OTDR for its distance scale calibration
Castellanos, E.; Bermudez, J. C.; Serroukh, I.
2006-02-01
An appropriate setting of the OTDR can help to improve the calibration reducing the uncertainty of measurements. We present some criterions for setting the Optical Time Domain Reflectometer (OTDR) for its distance scale calibration by means of a Recirculting Delay Line (RDL). The evaluation of some parameters such as location of the event, span of measurements, distance range and pulse width were carry out experimentally using a RDL calibrating system.
Exploring characteristics and motives of long distance commuter cyclists
DEFF Research Database (Denmark)
Hansen, Karsten Bruun; Sick Nielsen, Thomas
2014-01-01
, commuter cyclists (45 km from home to work) have more mobility options, higher incomes, and a longer education than other commuter cyclists. The main motive for longer distance cycling is physical exercise, followed by reduced costs and time used for traveling. The long distance commuter cyclists surveyed......, budgets to promote active travel to work as well as the role of psychological beneﬁts as a factor in promoting and sustaining cycling practices....
Exploring characteristics and motives of long distance commuter cyclists
DEFF Research Database (Denmark)
Hansen, Karsten Bruun; Nielsen, Thomas Alexander Sick
2014-01-01
, commuter cyclists (>5 km from home to work) have more mobility options, higher incomes, and a longer education than other commuter cyclists. The main motive for longer distance cycling is physical exercise, followed by reduced costs and time used for traveling. The long distance commuter cyclists surveyed......, budgets to promote active travel to work as well as the role of psychological benefits as a factor in promoting and sustaining cycling practices....
The anisotropy of perceived distance: The eyes story
Directory of Open Access Journals (Sweden)
Tošković Oliver
2011-01-01
Full Text Available The aim of this study is to determine whether the eye position shift changes perceived distance, that is, whether kinesthetic information from eye muscles affects distance perception. Two experiments were done, in a dark room (reduced-cue situation, with 27 participants, psychology undergraduates. Participants had a task to match distances of three stimuli, on three viewing directions, 0, 30 and 60 deg rees relative to the body. Head and body of participants were fixed, and they changed viewing directions only by moving their eyes. Stimuli were 7cm
Random Distances Associated with Rhombuses
Zhuang, Yanyan
2011-01-01
Parallelograms are one of the basic building blocks in two-dimensional tiling. They have important applications in a wide variety of science and engineering fields, such as wireless communication networks, urban transportation, operations research, etc. Different from rectangles and squares, the coordinates of a random point in parallelograms are no longer independent. As a case study of parallelograms, the explicit probability density functions of the random Euclidean distances associated with rhombuses are given in this report, when both endpoints are randomly distributed in 1) the same rhombus, 2) two parallel rhombuses sharing a side, and 3) two rhombuses having a common diagonal, respectively. The accuracy of the distance distribution functions is verified by simulation, and the correctness is validated by a recursion and a probabilistic sum. The first two statistical moments of the random distances, and the polynomial fit of the density functions are also given in this report for practical uses.
Preserving Terminal Distances using Minors
Krauthgamer, Robert
2012-01-01
We introduce the following notion of compressing an undirected graph G with edge-lengths and terminal vertices $R\\subseteq V(G)$. A distance-preserving minor is a minor G' (of G) with possibly different edge-lengths, such that $R\\subseteq V(G')$ and the shortest-path distance between every pair of terminals is exactly the same in G and in G'. What is the smallest f*(k) such that every graph G with k=|R| terminals admits a distance-preserving minor G' with at most f*(k) vertices? Simple analysis shows that $f*(k)\\leq O(k^4)$. Our main result proves that $f*(k)\\geq \\Omega(k^2)$, significantly improving over the trivial $f*(k)\\geq k$. Our lower bound holds even for planar graphs G, in contrast to graphs G of constant treewidth, for which we prove that O(k) vertices suffice.
Ghost imaging with broad distance
Institute of Scientific and Technical Information of China (English)
段德洋; 张路; 杜少将; 夏云杰
2015-01-01
We present a scheme that is able to achieve the ghost imaging with broad distance. The physical nature of our scheme is that the different wavelength beams are separated in free space by an optical media according to the slow light or dispersion principle. Meanwhile, the equality of the optical distance of the two light arms is not violated. The photon correlation is achieved by the rotating ground glass plate (RGGP) and spatial light modulator (SLM), respectively. Our work shows that a monochromic ghost image can be obtained in the case of RGGP. More importantly, the position (or distance) of the object can be ascertained by the color of the image. Thus, the imaging and ranging processes are combined as one process for the first time to the best of our knowledge. In the case of SLM, we can obtain a colored image regardless of where the object is.
Solving the molecular distance geometry problem with inaccurate distance data
Souza, Michael; Lavor, Carlile; Muritiba, Albert; Maculan, Nelson
2013-01-01
We present a new iterative algorithm for the molecular distance geometry problem with inaccurate and sparse data, which is based on the solution of linear systems, maximum cliques, and a minimization of nonlinear least-squares function. Computational results with real protein structures are presented in order to validate our approach.
RELACIONES TALLA-PESO DEL BARBUL (Pimelodus clarias f.c. Bloch, 1785 EN LA CUENCA DEL RIO SINU,
Directory of Open Access Journals (Sweden)
Iliana Santos-Sanes,
2006-12-01
Full Text Available Objetivo. Establecer las relaciones de talla y peso del barbul (Pimelodus clarias en la cuenca del río Sinú. Materiales y Métodos. Se estimaron las relaciones talla-peso de 4324 individuos de Barbul (Pimelodus clarias f.c. Bloch, 1785 colectados entre enero 2000 y diciembre 2002. Resultados. La longitud total (LT osciló entre 13.0-30.0 cm, promedio de 19.5 (±1.6 cm y el peso total (WT entre 20.0 y 248.1 g, promedio de 65.8 (±23.2 g. Las relaciones lineales estimadas fueron: LT = 1.92 (�� 0.16 + 1.20 (± 0.01 LS, r = 0.96; LT = 1.21 (± 0.16 + 1.15 (± 0.01 LH; r = 0.97 y LH = 0.91 (± 0.10 + 1.02 (± 0.01 LS, r = 0.97; con diferencias significativas entre las pendientes de la relación longitud estándar (LS-longitud horquilla (LH. La relación longitud-peso fue: WT = 0.005 (± 0.09 LT 3.16 (± 0.07, n = 4324, r = 0.81, con diferencias estadísticas significativas entre los diferentes coeficientes de crecimiento y factores de condición. Se encontró correlación entre el factor de condición, los niveles del Río Sinú y la época de desove del Barbul, la cual se extiende de marzo a octubre. Conclusión. Los resultados alcanzados en este estudio sugieren que las nuevas condiciones del río no han afectado la dinámica poblacional de la especie en lo que al crecimiento en talla y peso se refiere, y que el Barbul se ha adaptado a estas nuevas condiciones.
Explosion-Earthquake Discrimination at Local Distances
O'Rourke, C. T.; Baker, G. E.; Sheehan, A. F.; Harder, S. H.
2014-12-01
Event discrimination research has largely focused on regional distances over the last couple of decades. Most regional discriminants have not been thoroughly tested at local distances, and a recent investigation of P/S ratios from the Source Physics Experiment (SPE) found that they were less effective locally. As discrimination thresholds are reduced, local methods will need to be validated and the physical bases for their performance will need to be understood. We are assessing new and existing methods of source discrimination at 10 to 200 km distance. We use data from a temporary array deployed around the Bighorn Mountains in Wyoming and from nearby US Array stations. Small magnitude local earthquakes, coal mine explosions, and controlled borehole shots were recorded at over 200 broadband and short-period seismometers spaced at 5-35 km intervals across the tectonically complex area. We assess the local discrimination performance of the P/S amplitude ratio, the presence of the fundamental Rayleigh wave Rg, and the signature of scattered Rg in the coda. P/S amplitudes are used because earthquakes typically have higher S-wave energy relative to P than shallow explosions, but the separation of populations is not always effective at local distances. Site effects have a significant impact that may need to be accounted for, along with propagation effects. Specifically, relative P and S site amplifications at basin and mountain stations vary in such a way that they limit separation of the event populations. The Rg phase is only excited by near-surface events, so its presence indicates the likelihood of a man-made source since most earthquakes occur at too great a depth to excite Rg. We implement two methods for detecting Rg: one that uses the cross-correlation of the Hilbert transformed vertical and the radial seismograms, and one that scans a time-frequency representation for the signature of scattered Rg in the coda. These methods are effective in low signal
Entropy distance: New quantum phenomena
Energy Technology Data Exchange (ETDEWEB)
Weis, Stephan [Max Planck Institute for Mathematics in the Sciences, Inselstr. 22, D-04103 Leipzig (Germany); Knauf, Andreas [Department of Mathematics, Friedrich-Alexander-University Erlangen-Nuremberg, Cauerstr. 11, D-91058 Erlangen (Germany)
2012-10-15
We study a curve of Gibbsian families of complex 3 Multiplication-Sign 3-matrices and point out new features, absent in commutative finite-dimensional algebras: a discontinuous maximum-entropy inference, a discontinuous entropy distance, and non-exposed faces of the mean value set. We analyze these problems from various aspects including convex geometry, topology, and information geometry. This research is motivated by a theory of infomax principles, where we contribute by computing first order optimality conditions of the entropy distance.
Rindler force at large distances
Grumiller, Daniel
2011-01-01
Given some assumptions it is possible to derive the most general theory of gravity at large distances. The force law derived from this theory contains a Rindler term in addition to well-known contributions, a Schwarzschild mass and a cosmological constant. The same force law recently was confronted with solar system precision data. The Rindler force, if present in Nature, has intriguing consequences for gravity at large distances. In particular, the Rindler force is capable of explaining about 10% of the Pioneer anomaly and simultaneously ameliorates the shape of galactic rotation curves.
A contextual normalised edit distance
Higuera, Colin de la; Micó Andrés, Luisa
2008-01-01
In order to better fit a variety of pattern recognition problems over strings, using a normalised version of the edit or Levenshtein distance is considered to be an appropriate approach. The goal of normalisation is to take into account the lengths of the strings. We define a new normalisation, contextual, where each edit operation is divided by the length of the string on which the edit operation takes place. We prove that this contextual edit distance is a metric and that it can be...
Adaptive Distance Protection for Microgrids
DEFF Research Database (Denmark)
Lin, Hengwei; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez;
2015-01-01
Due to the increasing penetration of distributed generation resources, more and more microgrids can be found in distribution systems. This paper proposes a phasor measurement unit based distance protection strategy for microgrids in distribution system. At the same time, transfer tripping scheme is...... adopted to accelerate the tripping speed of the relays on the weak lines. The protection methodology is tested on a mid-voltage microgrid network in Aalborg, Denmark. The results show that the adaptive distance protection methodology has good selectivity and sensitivity. What is more, this system also has...
International Nuclear Information System (INIS)
It is possible to determine the h/mRb ratio between the Planck constant and the mass of the atoms, and then to deduce a value of the fine structure constant alpha, from the accurate measurement of the recoil velocity of an atom absorbing a photon. To perform this measurement we combine the high efficiency of Bloch oscillations with the high sensitivity of a Ramsey-Borde interferometer. The Bloch oscillations technic allows us to transfer a large number of recoils to the atoms (up to 1600 recoil momenta). An interferometric Ramsey-Borde velocity sensor, based on velocity selective Raman transitions, allows us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 3 ppb (3*10-9), in conjunction with a careful study of systematic effects (3.4 ppb), lead us to a determination of alpha with a relative uncertainty of 4.8 ppb. The value of α-1 is 137.03599887(65). It is the best determination of alpha, independent from quantum electrodynamics
Distance Education Instructional Model Applications.
Jackman, Diane H.; Swan, Michael K.
1995-01-01
A survey of graduate students involved in distance education on North Dakota State University's Interactive Video Network included 80 on campus and 13 off. The instructional models rated most effective were role playing, simulation, jurisprudential (Socratic method), memorization, synectics, and inquiry. Direct instruction was rated least…
Lessons in Developing Distance Learning.
Gant, Lenora Peters
1996-01-01
Describes the use of video teletraining (VTT) for distance learning in the Department of Defense. Topics include planning and organizing the VTT facility, staff development, site facilitators, the necessity of protocol, instructional design and development strategies, student involvement and interactivity, and evaluation and assessment. (LRW)
Religious Distance Education Goes Online
Frye, Steven B.
2012-01-01
Looking back on the use of distance education tools by religious groups, one word that stands out is change. The old adage "We've never done it that way before" will become less valid as religious bodies find themselves in the midst of a world inundated with online possibilities that call them to question how they interact with members and…
Opportunity Cost of Distance Education
Directory of Open Access Journals (Sweden)
Recep TURKOĞLU
2004-01-01
Full Text Available In this study; opportunity cost (OC of distance education (DE has been examined. In addition, Factors, which affect OC of DE, have been investigated according to institute, which develops DE and puts it into practice, student/parent whose target of DE program is and teacher who works for DE program.
Distance learning for hospital managers.
Whitener, L; Stevens, C; Cochran, K; Thompson, B G; Williams, M E
1999-01-01
Telemedicine technology enabled this class to meet. The Chapel Hill instructor could not have traveled to Scotland Neck for the classes, and the class members could not have taken time away from their jobs to travel to Chapel Hill. The technology allowed the participants to fit the classes into their schedules. For the group of managers at this small, isolated hospital, the experience of participating in a management class with an expert was a positive one. They were introduced to standard management practices, learned new skills, and formed a support group/team onsite. The students felt close to the leader, yet the physical distance made her an outsider in a way that encouraged frankness. The technology seemed to foster the best of both worlds--intimacy, yet physical distance and, thus, safety. These new managers were able to take part in a course that taught tangible skills for improving their job performance and, more important, afforded access to resources outside of Halifax County. They were able to step away from their daily routine and interact with outsiders and each other in new ways, without the stress and expense of travel. The results of this pilot study indicate that distance learning is feasible for courses of this kind. Staff burnout and turnover are chronic problems in rural facilities, with isolation contributing to job dissatisfaction. Distance learning offers exciting possibilities for addressing these problems in healthcare settings across the country. PMID:10847928
Imai, Keiko; Matoušek, Jiří; Reem, Daniel; Tokuyama, Takeshi
2009-01-01
The bisector of two nonempty sets P and Q in a metric space is the set of all points with equal distance to P and to Q. A distance k-sector of P and Q, where k is an integer, is a (k-1)-tuple (C_1, C_2, ..., C_{k-1}) such that C_i is the bisector of C_{i-1} and C_{i+1} for every i = 1, 2, ..., k-1, where C_0 = P and C_k = Q. This notion, for the case where P and Q are points in Euclidean plane, was introduced by Asano, Matousek, and Tokuyama, motivated by a question of Murata in VLSI design. They established the existence and uniqueness of the distance trisector in this special case. We prove the existence of a distance k-sector for all k and for every two disjoint, nonempty, closed sets P and Q in Euclidean spaces of any (finite) dimension, or more generally, in proper geodesic spaces (uniqueness remains open). The core of the proof is a new notion of k-gradation for P and Q, whose existence (even in an arbitrary metric space) is proved using the Knaster-Tarski fixed point theorem, by a method introduced by ...
Distance Learning: Untried and Untrue
Halfond, Jay A.
2010-01-01
G. K. Chesterton famously once said: "Christianity has not been tried and found wanting; it has been found difficult and not tried." This, the author believes, applies to distance learning as well. There is far too much self-congratulatory hyperbole about the growth and pervasiveness of online learning--which exaggerates reality and overlooks the…
Theological Librarianship from a Distance
Directory of Open Access Journals (Sweden)
Melody Diehl Detar
2015-08-01
Full Text Available This essay examines distance theological librarianship and the field’s suitability for remote librarians. A brief introduction to the landscape of online programs in theological education is followed by an overview of virtual librarianship and how theological librarians may serve students while working from a distance themselves. The essay then describes a method for initiating a remote librarian position in a theological library context, and then reviews the steps of determining whether remote work is feasible and desirable at an institution, approaching leadership with a plan, setting up a trial remote work period, and assessing its success. Particular emphasis is given to communication expectations, modes of virtual reference and instruction, campus committee service and meaningful ways of remaining part of the campus community.
The Gould's Belt distance survey
Loinard, L; Torres, R M; Dzib, S; Rodriguez, L F; Boden, A F
2011-01-01
Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object within 500 pc of the Sun to better than a few percent. Because they are magnetically active, young stars are often associated with compact radio emission detectable using VLBI techniques. Here we will show how VLBI observations have already constrained the distance to the most often studied nearby regions of star-formation (Taurus, Ophiuchus, Orion, etc.) and have started to provide information on their internal structure and kinematics. We will then briefly describe a large project (called The Gould's Belt Distance Survey) designed to provide a detailed view of star-formation in the Solar neighborhood using VLBI observations.
Moral distance in dictator games
Directory of Open Access Journals (Sweden)
Fernando Aguiar
2008-04-01
Full Text Available We perform an experimental investigation using a dictator game in which individuals must make a moral decision --- to give or not to give an amount of money to poor people in the Third World. A questionnaire in which the subjects are asked about the reasons for their decision shows that, at least in this case, moral motivations carry a heavy weight in the decision: the majority of dictators give the money for reasons of a consequentialist nature. Based on the results presented here and of other analogous experiments, we conclude that dicator behavior can be understood in terms of moral distance rather than social distance and that it systematically deviates from the egoism assumption in economic models and game theory. %extit{JEL}: A13, C72, C91
Sublinear distance labeling for sparse graphs
DEFF Research Database (Denmark)
Alstrup, Stephen; Dahlgaard, Søren; Knudsen, Mathias Bæk Tejs; Porat, Ely
A distance labeling scheme labels the $n$ nodes of a graph with binary strings such that, given the labels of any two nodes, one can determine the distance in the graph between the two nodes by looking only at the labels. A $D$-preserving distance labeling scheme only returns precise distances be...
47 CFR 73.808 - Distance computations.
2010-10-01
... Low Power FM Broadcast Stations (LPFM) § 73.808 Distance computations. For the purposes of determining compliance with any LPFM distance requirements, distances shall be calculated in accordance with § 73.208(c... 47 Telecommunication 4 2010-10-01 2010-10-01 false Distance computations. 73.808 Section...
History and Heritage in Distance Education
Anderson, Bill; Simpson, Mary
2012-01-01
Distance education's history is a tremendous resource for all involved in distance education. Some aspects of that history provide enduring touchstones for present distance educators, creating a heritage that should not be overlooked as distance education continues to develop and expand. In this article we draw on the concept of generational…
Distance Education Use in Rural Schools
Hannum, Wallace H.; Irvin, Matthew J.; Banks, Jonathan B.; Farmer, Thomas W.
2009-01-01
A national survey of rural school systems in the United States was conducted to determine the extent to which distance education is being utilized by rural schools, the technologies used, the curriculum areas impacted, the perceived needs for distance education, their satisfaction with distance education, and the barriers to distance education…
Effective Teaching in Distance Education. ERIC Digest.
Mielke, Dan
Distance education is an alternative method for delivering academic course work to students unable to attend traditional campus-based classes. This Digest presents information on the many forms of distance education and keys to successful teaching with distance education. Distance education is a method of education in which the learner is…
Elasticity of Long Distance Travelling
Knudsen, Mette Aagaard
2011-01-01
With data from the Danish expenditure survey for 12 years 1996 through 2007, this study analyses household expenditures for long distance travelling. Household expenditures are examined at two levels of aggregation having the general expenditures on transportation and leisure relative to five other aggregated commodities at the highest level, and the specific expenditures on plane tickets and travel packages at the lowest level. The Almost Ideal Demand System is applied to determine the relat...
Cosmological parallax-distance formula
Singal, Ashok K.
2015-09-01
The standard cosmological parallax-distance formula, as found in the literature, including text-books and reference books on cosmology, requires a correction. This correction stems from the fact that in the standard text-book derivation it has been ignored that any chosen baseline in a gravitationally bound system does not partake in the cosmological expansion. Though the correction is available in the literature for some time, the text-books still continue to use the older, incorrect formula, and its full implications are not yet fully realized. Apart from providing an alternate correct, closed-form expression that is more suitable and convenient for computations for certain limiting cases of FRW () world models, we also demonstrate how one can compute parallax distance for the currently favored flat-space accelerating-universe (, ) cosmologies. Further, we show that the correction in parallax distance at large redshifts could amount to a factor of three or even more. Moreover, even in an infinite universe the parallax distance does not increase indefinitely with redshift and that even the farthest possible observable point may have a finite parallax angle, a factor that needs to be carefully taken into account when using distant objects as the background field against which the parallax of a foreground object is to be measured. Some other complications that could arise in parallax measurements of a distant source, like that due to the deflection of incoming light by the gravitation field of the Sun and other planetary bodies in the solar system, are pointed out.
Geographical distance of innovation collaborations
Jeroen de Jong; Mark Freel
2010-01-01
This paper explores the geographical distance of innovation collaborations in high tech small firms. We test if absorptive capacity is a key determinant. Drawing on survey data from a sample of 316 Dutch high-tech small firms, engaging in 1.245 collaborations, we find most partners to be ‘local’. However, controlling for a variety of potential influences, higher R&D expenditure is positively related to collaboration with more distant organisations.
Distance function of D numbers
Li, Meizhu; Zhang, Qi; Deng, Xinyang; Deng, Yong
2014-01-01
Dempster-Shafer theory is widely applied in uncertainty modelling and knowledge reasoning due to its ability of expressing uncertain information. A distance between two basic probability assignments(BPAs) presents a measure of performance for identification algorithms based on the evidential theory of Dempster-Shafer. However, some conditions lead to limitations in practical application for Dempster-Shafer theory, such as exclusiveness hypothesis and completeness constraint. To overcome these...
Entropy distance: New quantum phenomena
Weis, Stephan; Knauf, Andreas
2012-01-01
We study a curve of Gibbsian families of complex 3 × 3-matrices and point out new features, absent in commutative finite-dimensional algebras: a discontinuous maximum-entropy inference, a discontinuous entropy distance, and non-exposed faces of the mean value set. We analyze these problems from various aspects including convex geometry, topology, and information geometry. This research is motivated by a theory of infomax principles, where we contribute by computing first order optimality cond...
Reduced dynamics for entangled initial state of the full density operator
International Nuclear Information System (INIS)
Starting from the Schroedinger equation for a system and a reservoir, we construct a quantum dynamical map that describes reduced dynamics. We work with an arbitrary initial state for the system and reservoir, and thus refrain from performing any factorizations. The map is found to be nonlinear, not completely positive, and not unique. To investigate the physical implications, the Bloch equations are constructed. If the freedom the new map offers us is fully exploited, then the classic inequality γperpedicular≥γparalell/2 for the damping coefficients must be replaced by a weaker condition. (author)
Coupling-reducing k-points for photonic crystal fibre calculations
DEFF Research Database (Denmark)
Albertsen, Maja; Lægsgaard, Jesper; Barkou Libori, Stig Eigil;
2003-01-01
of the transverse Bloch wave vector, k. We describe a method to derive k-points that minimize the coupling between repeated images of the guided modes in real space. Calculations have been done for a quadratic and a triangular photonic crystal fiber structure. With the new coupling reducing (CR) k......When describing localized electromagnetic modes in dielectric waveguides by the planewave method, a supercell geometry must necessarily be adopted. We demonstrate in the present work that the convergence of the calculations with respect to supercell size depends strongly on the choice...
Support Services for Distance Education
Directory of Open Access Journals (Sweden)
Sandra Frieden
1999-01-01
Full Text Available The creation and operation of a distance education support infrastructure requires the collaboration of virtually all administrative departments whose activities deal with students and faculty, and all participating academic departments. Implementation can build on where the institution is and design service-oriented strategies that strengthen institutional support and commitment. Issues to address include planning, faculty issues and concerns, policies and guidelines, approval processes, scheduling, training, publicity, information-line operations, informational materials, orientation and registration processes, class coordination and support, testing, evaluations, receive site management, partnerships, budgets, staffing, library and e-mail support, and different delivery modes (microwave, compressed video, radio, satellite, public television/cable, video tape and online. The process is ongoing and increasingly participative as various groups on campus begin to get involved with distance education activities. The distance education unit must continuously examine and revise its processes and procedures to maintain the academic integrity and service excellence of its programs. Its a daunting prospect to revise the way things have been done for many years, but each department has an opportunity to respond to new ways of serving and reaching students.
Ghost imaging with broad distance
Duan, De-Yang; Zhang, Lu; Du, Shao-Jiang; Xia, Yun-Jie
2015-10-01
We present a scheme that is able to achieve the ghost imaging with broad distance. The physical nature of our scheme is that the different wavelength beams are separated in free space by an optical media according to the slow light or dispersion principle. Meanwhile, the equality of the optical distance of the two light arms is not violated. The photon correlation is achieved by the rotating ground glass plate (RGGP) and spatial light modulator (SLM), respectively. Our work shows that a monochromic ghost image can be obtained in the case of RGGP. More importantly, the position (or distance) of the object can be ascertained by the color of the image. Thus, the imaging and ranging processes are combined as one process for the first time to the best of our knowledge. In the case of SLM, we can obtain a colored image regardless of where the object is. Project supported by the National Natural Science Foundation of China (Grant Nos. 61178012, 11204156, 11304179, and 11247240), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20133705110001 and 20123705120002), the Scientific Research Foundation for Outstanding Young Scientists of Shandong Province, China (Grant No. BS2013DX034), and the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ024).
Patient education at a distance
International Nuclear Information System (INIS)
Introduction: Historically, education of patients was paternalistic where people have been conditioned to do as the 'doctor' tells them. Traditionally this worked as people tended to have limited access to knowledge of treatment regimen available. However, in the information age, this knowledge is more readily available and it is now common practice to educate people diagnosed with cancer about their treatment and disease process. In fact, dissemination of information is now an intrinsic part of cancer care. Purpose: The primary aim of this study was to investigate the practice of patient education for gynaecological cancers treated with brachytherapy and review the feasibility of designing a distance learning information tool to inform patients about a clinical treatment option available to them in the cancer agency. Methods: The study was divided into two parts. Part 1 was a review of adult learning principles and clinical application. Part 2 explored the feasibility of moving from face-to-face to distance learning in this situation. Conclusions: Adaptation of clinical patient education from a face-to-face learning situation to distance education could be very successful if the basic principles of adult education and facilitation are followed and special care given to maintaining open lines of communication/support for the distant patient
Patient education at a distance
Energy Technology Data Exchange (ETDEWEB)
Mitchell, Fiona [Radiation Therapy, BC Cancer Agency, 600 West 10th Avenue, Vancouver, BC V5Z 4E6 (Canada)]. E-mail: fmitchel@bccancer.bc.ca
2007-02-15
Introduction: Historically, education of patients was paternalistic where people have been conditioned to do as the 'doctor' tells them. Traditionally this worked as people tended to have limited access to knowledge of treatment regimen available. However, in the information age, this knowledge is more readily available and it is now common practice to educate people diagnosed with cancer about their treatment and disease process. In fact, dissemination of information is now an intrinsic part of cancer care. Purpose: The primary aim of this study was to investigate the practice of patient education for gynaecological cancers treated with brachytherapy and review the feasibility of designing a distance learning information tool to inform patients about a clinical treatment option available to them in the cancer agency. Methods: The study was divided into two parts. Part 1 was a review of adult learning principles and clinical application. Part 2 explored the feasibility of moving from face-to-face to distance learning in this situation. Conclusions: Adaptation of clinical patient education from a face-to-face learning situation to distance education could be very successful if the basic principles of adult education and facilitation are followed and special care given to maintaining open lines of communication/support for the distant patient.
Parameter-Free Extended Edit Distance
Muhammad Fuad, Muhammad Marwan
2014-01-01
The edit distance is the most famous distance to compute the similarity between two strings of characters. The main drawback of the edit distance is that it is based on local procedures which reflect only a local view of similarity. To remedy this problem we presented in a previous work the extended edit distance, which adds a global view of similarity between two strings. However, the extended edit distance includes a parameter whose computation requires a long training time. In this paper w...
Editorial ~ Global Diversity of Distance Education
Peter S. Cookson
2001-01-01
In a panel presentation at the recent International Council for Open and Distance Education (ICDE) world conference in Dusseldorf, Germany, I had the opportunity to explain the unique role and mission of International Review of Research in Open and Distance Learning (IRRODL) vis – vis our more established sister journals: Open Praxis, Open Learning, Journal of Distance Education, Distance Education, and American Journal of Distance Education. Although all of these journals share a common comm...
Wu, Xiao-Yu; Tian, Bo; Zhen, Hui-Ling; Sun, Wen-Rong; Sun, Ya
2016-03-01
Under investigation in this paper is a set of the ?-dimensional nonlinear Schrödinger-Maxwell-Bloch (NLS-MB) equations, which describes the optical pulse propagation in an erbium-doped fibre. Employing the Hirota method and symbolic computation, we obtain the one- two- and N-soliton solutions. We prove that the interactions between the two solitons are elastic through the asymptotic analysis on the soliton solutions. Figures are plotted to show the one soliton and the interaction between the two solitons. We find that the decrease of the frequency shift from the resonance can make the angle between the propagation directions and the amplitudes of the two MB solitons bigger, implying that the change of the amplitudes of the two MB solitons is closely related to the propagation directions of the two NLS solitons.
Zeitoun, Philippe; Oliva, Eduardo; Fajardo, Marta; Ros, David; Sebban, Stéphane; Velarde, Pedro
2011-12-01
Seeding plasma-based soft x-ray laser (SXRL) demonstrated diffraction-limited, fully coherent in space and in time beam but with energy not exceeding 1 μJ per pulse. Quasi-steady-state (QSS) plasmas demonstrated to be able to store high amount of energy and then amplify incoherent SXRL up to several mJ. Using 1D time-dependant Bloch-Maxwell model including amplification of noise, we demonstrated that femtosecond HHG cannot be efficiently amplified in QSS plasmas. However, using Chirped Pulse Amplification concept on HHG seed allows to extract most of the stored energy, reaching up to 5 mJ in fully coherent pulses that can be compressed down to 130 fs.
Mattig's relation and dynamical distance indicators
Teerikorpi, Pekka
2016-01-01
We discuss how the redshift (Mattig) method in Friedmann cosmology relates to dynamical distance indicators based on Newton's gravity (Teerikorpi 2011). It belongs to the class of indicators where the relevant length inside the system is the distance itself (in this case the proper metric distance). As the Friedmann model has Newtonian analogy, its use to infer distances has instructive similarities to classical dynamical distance indicators. In view of the theoretical exact linear distance-velocity law, we emphasize that it is conceptually correct to derive the cosmological distance via the route: redshift (primarily observed) --> space expansion velocity (not directly observed) --> metric distance (physical length in "cm"). Important properties of the proper metric distance are summarized.
Mattig's relation and dynamical distance indicators
Teerikorpi, P.; Baryshev, Yu. V.
2016-03-01
We discuss how the redshift (Mattig) method in the Friedmann cosmology relates to dynamical distance indicators based on Newton's gravity (Teerikorpi 2011). It belongs to the class of indicators where the relevant length inside the system is the distance itself (in this case the proper metric distance). As the Friedmann model has a Newtonian analogy, its use to infer distances has instructive similarities to classical dynamical distance indicators. In view of the theoretical exact linear distance-velocity law, we emphasize that it is conceptually correct to derive the cosmological distance via the route: redshift (primarily observed) -> space expansion velocity (not directly observed) -> metric distance (physical length in ``cm''). Important properties of the proper metric distance are summarized.
Distance Measurement Solves Astrophysical Mysteries
2003-08-01
Location, location, and location. The old real-estate adage about what's really important proved applicable to astrophysics as astronomers used the sharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA) to pinpoint the distance to a pulsar. Their accurate distance measurement then resolved a dispute over the pulsar's birthplace, allowed the astronomers to determine the size of its neutron star and possibly solve a mystery about cosmic rays. "Getting an accurate distance to this pulsar gave us a real bonanza," said Walter Brisken, of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Monogem Ring The Monogem Ring, in X-Ray Image by ROSAT satellite CREDIT: Max-Planck Institute, American Astronomical Society (Click on Image for Larger Version) The pulsar, called PSR B0656+14, is in the constellation Gemini, and appears to be near the center of a circular supernova remnant that straddles Gemini and its neighboring constellation, Monoceros, and is thus called the Monogem Ring. Since pulsars are superdense, spinning neutron stars left over when a massive star explodes as a supernova, it was logical to assume that the Monogem Ring, the shell of debris from a supernova explosion, was the remnant of the blast that created the pulsar. However, astronomers using indirect methods of determining the distance to the pulsar had concluded that it was nearly 2500 light-years from Earth. On the other hand, the supernova remnant was determined to be only about 1000 light-years from Earth. It seemed unlikely that the two were related, but instead appeared nearby in the sky purely by a chance juxtaposition. Brisken and his colleagues used the VLBA to make precise measurements of the sky position of PSR B0656+14 from 2000 to 2002. They were able to detect the slight offset in the object's apparent position when viewed from opposite sides of Earth's orbit around the Sun. This effect, called parallax, provides a direct measurement of
ECONOMICS OF DISTANCE EDUCATION RECONSIDERED
Laaser, Wolfram
2008-01-01
ABSTRACT According to Gartner a certain hype of e-Learning was followed by a downturn but eLearning will continue to be an important factor in learning scenarios. However the economic viability of e-learning projects will be questioned with more scrutiny than in earlier periods. Therefore it seems to be a good opportunity to see what can be learned from past experience in costing distance learning projects and what aspects are added by current attempts to measure economic efficiency. After r...
Social interaction distance and stratification
Wendy Bottero amd Ken Prandy.
2003-01-01
There have been calls from several sources recently for a renewal of class analysis that would encompass social and cultural, as well as economic elements. This paper explores a tradition in stratification that is founded on this idea: relational or social distance approaches to mapping hierarchy and inequality which theorize stratification as a social space. The idea of âsocial spaceâ is not treated as a metaphor of hierarchy nor is the nature of the structure determined a priori. Rather...
Unit Distances in Three Dimensions
Kaplan, Haim; Safernova, Zuzana; Sharir, Micha
2011-01-01
We show that the number of unit distances determined by n points in R^3 is O(n^{3/2}), slightly improving the bound of Clarkson et al. established in 1990. The new proof uses the recently introduced polynomial partitioning technique of Guth and Katz [arXiv:1011.4105]. While this paper was still in a draft stage, a similar proof of our main result was posted to the arXiv by Joshua Zahl [arXiv:1104.4987].
Offsets in Electrostatically Determined Distances: Implications for Casimir Force Measurements
Lamoreaux, S K
2011-01-01
The imperfect termination of static electric fields at semiconducting surfaces has been long known in solid state and transistor physics. We show that the imperfect shielding leads to an offset in the distance between two surfaces as determined by electrostatic force measurements. The effect exists even in the case of good conductors (metals) albeit much reduced.
NEW HAUSDORFF DISTANCE-BASED VEHICLE LOCATION
Institute of Scientific and Technical Information of China (English)
陈莹; 韩崇昭
2004-01-01
Objective To realize accurate localization of moving vehicles from single monocular intensity image. Methods The new modified Hausdorff distance(M2HD) was adopted, which used dominant points instead of edge maps as features for measuring similarity between image and model projection. Modified simulated annealing (MSA) algorithm was used to find optimum localization parameters. Results M2HD reduces the computational complexity, and improves the matching precision. Furthermore, MSA can fast find global optimum instead of getting into partial one because of its high parallel and robust performance. Conclusion Experiments confirm that the combination of MSA and M2HD can effectively localize the vehicles that are changed both in translation and rotation
Quantum chromodynamics at large distances
International Nuclear Information System (INIS)
The properties of quantum chromodynamics (QCD)at large distances are considered in the framework of traditional quantum field theory. The parameters that determine the infrared region are determined self-consistently by means of the renormalization-group method. Recent studies that confirm a singular infrared asymptotic behavior M2 /(k2 )2 of the gluon propagator are reviewed. Solutions of the Schwinger--Dyson equation for the quark propagator are found with the necessary properties: spontaneous breaking of the chiral invariance and a nonperturbative nature. The infrared behaviors of the lowest Green's functions are used to calculate the vacuum expectation values of the gluon and quark fields. Good agreement between the calculated vacuum expectation values and their phenomenological values is obtained. The study of the behavior of QCD at large distances leads to the conclusion that at the present level of development of the theory two possibilities can be discussed. The first is the well-known confinement hypothesis; the second has been called incomplete confinement and necessarily implies that open color can be observed. It is shown that the second possibility does not contradict existing experiments. Experimental data on anomalous nuclear fragments and ultra-high-energy radiation from the galactic source Cygnus X-3 are considered as evidence for incomplete confinement. The importance of searches for states with open color is emphasized
Indo-European languages tree by Levenshtein distance
Serva, M.; Petroni, F.
2008-03-01
The evolution of languages closely resembles the evolution of haploid organisms. This similarity has been recently exploited (Gray R. D. and Atkinson Q. D., Nature, 426 (2003) 435; Gray R. D. and Jordan F. M., Nature, 405 (2000) 1052) to construct language trees. The key point is the definition of a distance among all pairs of languages which is the analogous of a genetic distance. Many methods have been proposed to define these distances; one of these, used by glottochronology, computes the distance from the percentage of shared "cognates". Cognates are words inferred to have a common historical origin, and subjective judgment plays a relevant role in the identification process. Here we push closer the analogy with evolutionary biology and we introduce a genetic distance among language pairs by considering a renormalized Levenshtein distance among words with same meaning and averaging on all words contained in a Swadesh list (Swadesh M., Proc. Am. Philos. Soc., 96 (1952) 452). The subjectivity of process is consistently reduced and the reproducibility is highly facilitated. We test our method against the Indo-European group considering fifty different languages and the two hundred words of the Swadesh list for any of them. We find out a tree which closely resembles the one published in Gray and Atkinson (2003), with some significant differences.
Automated working distance adjustment for a handheld OCT-Laryngoscope
Donner, Sabine; Bleeker, Sebastian; Ripken, Tammo; Krueger, Alexander
2014-03-01
Optical coherence tomography (OCT) is an imaging technique which enables diagnosis of vocal cord tissue structure by non-contact optical biopsies rather than invasive tissue biopsies. For diagnosis on awake patients OCT was adapted to a rigid indirect laryngoscope. The working distance must match the probe-sample distance, which varies from patient to patient. Therefore the endoscopic OCT sample arm has a variable working distance of 40 mm to 80 mm. The current axial position is identified by automated working distance adjustments based on image processing. The OCT reference plane and the focal plane of the sample arm are moved according to position errors. Repeated position adjustment during the whole diagnostic procedure keeps the tissue sample at the optimal axial position. The auto focus identifies and adjusts the working distance within the range of 50 mm within a maximum time of 2.7 s. Continuous image stabilisation reduces axial sample movement within the sampling depth for handheld OCT scanning. Rapid autofocus reduces the duration of the diagnostic procedure and axial position stabilisation eases the use of the OCT laryngoscope. Therefore this work is an important step towards the integration of OCT into indirect laryngoscopes.
Measuring Corporate Readiness To Implement Distance Education.
Slick, Joan Friton
2001-01-01
Examines distance education issues for corporations and offers a measurement tool to assess corporate readiness for distance education. Topics include costs; competitive advantages; customized training; effectiveness; organizational support; instructional design; managerial support; and learner attitudes. (Author/LRW)
WEIGHTING DISTANCE MATRICES USING RANK CORRELATIONS
Ilaria Lucrezia Amerise; Agostino Tarsitano
2012-01-01
In a number of applications of multivariate analysis, the data matrix is not fully observed. Instead a set of distance matrices on the same entities is available. A reasonable strategy to construct a global distance matrix is to compute a weighted average of the partial distance matrices, provided that an appropriate system of weights can be defined. The Distatis method developed by Abdi et al. (2005) is a three-step procedure for computing the global distance matrix. An important aspect of t...
Explaining the National Cultural Distance Paradox
Keith D Brouthers; Lance Eliot Brouthers
2001-01-01
Past studies of the relationship between national cultural distance and entry mode choice have produced conflicting results. Some scholars find cultural distance associated with choosing wholly owned modes; others find cultural distance linked to a preference for joint ventures. In this paper we provide both theoretical and empirical evidence to explain the discrepant findings and thus, help to resolve the national cultural distance paradox.© 2001 JIBS. Journal of International Business Studi...
Sleeping distance in wild wolf packs
Knick, S.T.; Mech, L.D.
1980-01-01
Sleeping distances were observed among members of 13 wild wolf (Canis lupus) packs and 11 pairs in northeastern Minnesota to determine if the distances correlated with pack size and composition. The study utilized aerial radio-tracking and observation during winter. Pack size and number of adults per pack were inversely related to pack average sleeping distance and variability. No correlation between sleeping distance and microclimate was observed. Possible relationships between social bonding and our results are discussed.
ROUGH WAY FOR ACADEMICS: Distance Education
GURSUL, Fatih
2010-01-01
This study aims to compare the academics’ perceptions about face to face and distance education, beside finding out the contributions of distance education to them, difficulties they experience in synchronous and asynchronous distance education environments and suggestions for possible solutions of the existing problems. The sample consists of 52 instructors providing distance education courses actively at 7 universities in Turkey, in 2009-2010 academic year. As data collection tool, a su...
THE INFLUENCE OF WOMEN ON DISTANCE EDUCATION
Gail D. CARUTH
2014-01-01
The impact of distance education on women has been significant. Distance education has been a viable means for helping women reach their educational ambitions. Over the last 40 years distance education has increased the ease of access and control over study time. With geographical and time barriers removed, women in particular were able to add the role of student to their list of responsibilities. Women have defeated educational barriers through educational opportunities presented by distance...
The Distances of the Magellanic Clouds
Walker, Alistair R.
1998-01-01
The present status of our knowledge of the distances to the Magellanic Clouds is evaluated from a post-Hipparcos perspective. After a brief summary of the effects of structure, reddening, age and metallicity, the primary distance indicators for the Large Magellanic Cloud are reviewed: The SN 1987A ring, Cepheids, RR Lyraes, Mira variables, and Eclipsing Binaries. Distances derived via these methods are weighted and combined to produce final "best" estimates for the Magellanic Clouds distance ...
Distance Education in Turkish Higher Education
Ömür AKDEMİR
2011-01-01
The term distance education is used to define education where educators and learners are physically separated. The first use of the distance education as a term goes back to 1924 in Turkey. Establishment of the Open Education Faculty of Anadolu University is the first initiative for the appearance of distance education in the Turkish Higher Education. Distance education is offered at different levels of higher education at present. Changes happening in technology and students characteristics ...
FEMALE ADMINISTRATORS PERCEPTIONS OF DISTANCE LEARNING
Mundy, Marie-Anne; Kupczynski, Lori; DAVIS, Rebecca; SPILLETT, Marydee A.
2014-01-01
Gender disparity is evident in tenure track and tenured faculty positions at universities. However, distance education may provide more supportive environments for female academicians to grow and develop. The term distance learning is used to encompass any type of instruction delivered off campus. Distance learning has increased dramatically and has gained strategic importance possibly presenting women with a new realm for advancement. Leaders in distance learning must have qualities such as ...
Angular Diameter Distances in Clumpy Friedmann Universes
Tomita, Kenji
1998-01-01
Solving null-geodesic equations, behavior of angular diameter distances is studied in inhomogeneous cosmological models, which are given by performing N-body simulations with the CDM spectrum. The distances depend on the separation angle of ray pairs, the mass and the radius of particles cosisting of galaxies and dark matter balls, and cosmological model parameters. The calculated distances are compared with the Dyer- Roeder distance, and after many ray-shooting, the average, dispersion and d...
Levenshtein Distance Technique in Dictionary Lookup Methods: An Improved Approach
Haldar, Rishin
2011-01-01
Dictionary lookup methods are popular in dealing with ambiguous letters which were not recognized by Optical Character Readers. However, a robust dictionary lookup method can be complex as apriori probability calculation or a large dictionary size increases the overhead and the cost of searching. In this context, Levenshtein distance is a simple metric which can be an effective string approximation tool. After observing the effectiveness of this method, an improvement has been made to this method by grouping some similar looking alphabets and reducing the weighted difference among members of the same group. The results showed marked improvement over the traditional Levenshtein distance technique.
Perceptual constancy in judgments of egocentric distance: prevailing binocular information
Directory of Open Access Journals (Sweden)
Matsushima Elton H.
2003-01-01
Full Text Available Binocular cues were considered the prevailing information on specifying depth since the beginning of vision research. In the present study, two perceptual responses, the classical verbal report and a more recent method, open-loop walking, were used to assess the role of binocular information for egocentric distance perception. In two cue conditions environments, full- and reduced-cue, observers judged and walked egocentric distances of stimuli presented at eye-level, under binocular or monocular viewing. Results indicated perceptual constancy for open-loop walking and binocular responses, as well as poor performances under strong degradation on visual information (reduced-cue under monocular viewing, thus presenting evidence to support the fundamental role of binocular information on perception of egocentric distances. Besides that, visually directed actions could be adequate measures of perceived distance, with a better reliability than verbal report, since they were quite free of intrusion of inferential processes and perceptual tendencies. In addition, reduced head movements, side-to-side as well as back and forth deflexion movements, could have contributed to a near perfect coupling between binocular disparity information and open-loop walking responses.
Continuity Properties of Distances for Markov Processes
DEFF Research Database (Denmark)
Jaeger, Manfred; Mao, Hua; Larsen, Kim Guldstrand;
2014-01-01
In this paper we investigate distance functions on finite state Markov processes that measure the behavioural similarity of non-bisimilar processes. We consider both probabilistic bisimilarity metrics, and trace-based distances derived from standard Lp and Kullback-Leibler distances. Two desirable...
Rough Way for Academics: Distance Education
Gursul, Fatih
2010-01-01
This study aims to compare the academics' perceptions about face to face and distance education, beside finding out the contributions of distance education to them, difficulties they experience in synchronous and asynchronous distance education environments and suggestions for possible solutions of the existing problems. The sample consists…
Financial Applications of the Mahalanobis Distance
2014-01-01
We describe existing and potential financial applications of the Mahalanobis distance. After a short motivation and a discussion of important properties of this multivariate distance measure, we classify its applications in finance according to the source and nature of its input parameters. Examples illustrate the usefulness of these applications of the Mahalanobis distance for financial market participants.
Perspectives of Research on Distance Education.
Holmberg, Borje
The history of research on distance education was studied. Major research done on distance education in such diverse areas as the United States, Venezuela, and Europe was analyzed. It was discovered that the earliest attempts to develop theories of distance education were mainly concerned with identifying its very concept. Like most educational…
Reduced Calibration Curve for Proton Computed Tomography
Yevseyeva, Olga; de Assis, Joaquim; Evseev, Ivan; Schelin, Hugo; Paschuk, Sergei; Milhoretto, Edney; Setti, João; Díaz, Katherin; Hormaza, Joel; Lopes, Ricardo
2010-05-01
The pCT deals with relatively thick targets like the human head or trunk. Thus, the fidelity of pCT as a tool for proton therapy planning depends on the accuracy of physical formulas used for proton interaction with thick absorbers. Although the actual overall accuracy of the proton stopping power in the Bethe-Bloch domain is about 1%, the analytical calculations and the Monte Carlo simulations with codes like TRIM/SRIM, MCNPX and GEANT4 do not agreed with each other. A tentative to validate the codes against experimental data for thick absorbers bring some difficulties: only a few data is available and the existing data sets have been acquired at different initial proton energies, and for different absorber materials. In this work we compare the results of our Monte Carlo simulations with existing experimental data in terms of reduced calibration curve, i.e. the range—energy dependence normalized on the range scale by the full projected CSDA range for given initial proton energy in a given material, taken from the NIST PSTAR database, and on the final proton energy scale—by the given initial energy of protons. This approach is almost energy and material independent. The results of our analysis are important for pCT development because the contradictions observed at arbitrary low initial proton energies could be easily scaled now to typical pCT energies.
Editorial ~ Global Diversity of Distance Education
Directory of Open Access Journals (Sweden)
Peter S. Cookson
2001-07-01
Full Text Available In a panel presentation at the recent International Council for Open and Distance Education (ICDE world conference in Dusseldorf, Germany, I had the opportunity to explain the unique role and mission of International Review of Research in Open and Distance Learning (IRRODL vis – vis our more established sister journals: Open Praxis, Open Learning, Journal of Distance Education, Distance Education, and American Journal of Distance Education. Although all of these journals share a common commitment to the advancement of the knowledge and practice of open and distance education, each one has a unique role and mission. As the non-refereed international publication of ICDE, Open Praxis focuses primarily on distance education practice worldwide. As a refereed journal based at the Open University (UK, Open Learning regularly publishes articles relating to other parts of the world, although its primary emphasis is distance education theory, research, and practice with a British accent. As the official publication of the Canadian Association of Distance Education, Journal of Distance Education understandably focuses on Canadian distance education, although a significant number of articles in each issue relate to other parts of the world. As another example of an official publication of a national association, (Open and Distance Learning Association of Australia, Distance Education features several articles in most issues describing theory, research and/or practice in other countries. As is consonant with the geographical scope explicit in its title, American Journal of Distance Education emphasizes North American contributions to the theory, research and practice of distance education in North America, although contributions appear occasionally from other parts of the globe.
Generating Signed Distance Fields From Triangle Meshes
DEFF Research Database (Denmark)
Bærentzen, Jakob Andreas; Aanæs, Henrik
A method for generating a discrete, signed 3D distance field is proposed. Distance fields are used in a number of contexts. In particular the popular level set method is usually initialized by a distance field. The main focus of our work is on simplifying the computation of the sign when generating...... leads to a method for generating signed distance fields which is a simple and straightforward extension of the method for generating unsigned distance fields. We prove that our choice of pseudo normal leads to a correct technique for computing the sign....
Continuing engineering education through distance learning
Baukal, C. E.
2010-05-01
The demand for distance continuing engineering education (CEE) is growing. This article describes the following with regard to CEE: the purpose; its importance, trends and unique challenges. Distance education can meet some of these challenges. Benefits and challenges of distance CEE are discussed along with the different types of distance CEE providers including universities, professional and trade organisations, corporate universities, for-profit education providers and government. Some recommendations are given for distance CEE. The specific focus here is on non-degree courses that are generally highly practical and focused.
Institute of Scientific and Technical Information of China (English)
陈昊; 陈小明
2011-01-01
In this paper, we analyse the relationship between cultural distance and export based on the theory of Hofstede＇s five cultural dimensions from the two aspects ：transaction costs and consumer choice. Then we use the data of 19 major trade partners of China in 2003-2009, relying on the modified gravity model, empirical tests cultures from marginal impact on export trade and extent. This study shows that, for every 1% increase in cultural distance, export volume decreased by about 0.185 % , showing that cultural distance exists on the export trade, hinder the development of that culture from the path based on the im- pact of transaction costs than the path based on the impact of consumer choice more significantly. Therefore, exporters should be improved through product design and shorten the trading partners and the cuhural distance between countries, increase the cultural identity of the host country market and the degree of consumers, to improve the level of exports and efficiency.%在借鉴Hofstede文化五维度理论的基础上，从交易成本和消费者选择两个方面分析了文化距离对出口贸易的影响路径，并基于2003-2009年中国19个主要贸易伙伴国家的对外贸易和文化距离数据样本，依靠修正的引力模型，实证检验文化距离对出口贸易的边际影响方向和程度。本文研究表明，文化距离每提高1％，出口贸易额就降低约0．185％，可见交易成本路径依然是文化距离对出口贸易的主要影响机制。
Learner characteristics involved in distance learning
Energy Technology Data Exchange (ETDEWEB)
Cernicek, A.T.; Hahn, H.A.
1991-01-01
Distance learning represents a strategy for leveraging resources to solve educational and training needs. Although many distance learning programs have been developed, lessons learned regarding differences between distance learning and traditional education with respect to learner characteristics have not been well documented. Therefore, we conducted a survey of 20 distance learning professionals. The questionnaire was distributed to experts attending the second Distance Learning Conference sponsored by Los Alamos National Laboratory. This survey not only acquired demographic information from each of the respondents but also identified important distance learning student characteristics. Significant distance learner characteristics, which were revealed statistically and which influence the effectiveness of distance learning, include the following: reading level, student autonomy, and self-motivation. Distance learning cannot become a more useful and effective method of instruction without identifying and recognizing learner characteristics. It will be important to consider these characteristics when designing all distance learning courses. This paper will report specific survey findings and their implications for developing distance learning courses. 9 refs., 6 tabs.
Critical Points in Distance Learning System
Directory of Open Access Journals (Sweden)
Airina Savickaitė
2013-08-01
Full Text Available Purpose – This article presents the results of distance learning system analysis, i.e. the critical elements of the distance learning system. The critical points of distance learning are a part of distance education online environment interactivity/community process model. The most important is the fact that the critical point is associated with distance learning participants. Design/methodology/approach – Comparative review of articles and analysis of distance learning module. Findings – A modern man is a lifelong learner and distance learning is a way to be a modern person. The focus on a learner and feedback is the most important thing of learning distance system. Also, attention should be paid to the lecture-appropriate knowledge and ability to convey information. Distance system adaptation is the way to improve the learner’s learning outcomes. Research limitations/implications – Different learning disciplines and learning methods may have different critical points. Practical implications – The information of analysis could be important for both lecturers and students, who studies distance education systems. There are familiar critical points which may deteriorate the quality of learning. Originality/value – The study sought to develop remote systems for applications in order to improve the quality of knowledge. Keywords: distance learning, process model, critical points. Research type: review of literature and general overview.
Do Improvements in Balance Relate to Improvements in Long-Distance Walking Function after Stroke?
Awad, Louis N.; Reisman, Darcy S.; Binder-Macleod, Stuart A.
2014-01-01
Stroke survivors identify a reduced capacity to walk farther distances as a factor limiting their engagement at home and in community. Previous observational studies have shown that measures of balance ability and balance self-efficacy are strong predictors of long-distance walking function after stroke. Consequently, recommendations to target balance during rehabilitation have been put forth. The purpose of this study was to determine if the changes in balance and long-distance walking funct...
The Distances of the Galactic Novae
Özdönmez, Aykut; Cabrera-Lavers, Antonio; Ak, Tansel
2016-01-01
Utilising the unique location of red clump giants on colour-magnitude diagrams obtained from various near-IR surveys, we derived specific reddening-distance relations towards 119 Galactic novae for which independent reddening measurements are available. Using the derived distance-extinction relation and the independent measurements of reddening we calculated the most likely distances for each system. We present the details of our distance measurement technique and the results of this analysis, which yielded the distances of 73 Galactic novae and allowed us to set lower limits on the distances of 46 systems. We also present the data of reddening-distance relations derived for each nova, which may be useful to analyze the different Galactic components present in the line of sight.
Gallant, Joseph
1999-04-01
One of the goals of physics education is to instill a sense of wonder in our students. We hope our natural curiosity will rub off on them and that they will apply the critical thinking skills we teach them to other aspects of their lives outside the classroom. As an example of this, consider the situation described in Milton's epic poem ``Paradise Lost''. Milton wrote that when the devil was cast out of heaven, he fell for nine days before landing in hell. In Milton's universe, hell is a separate place from Earth, but many people place hell at the center of the Earth. Based on these ideas, we can apply Newton's laws of motion to calculate the distance from heaven to Earth. This exercise is an example of the kind of intellectual exercise a physicist (or a physics student) might carry out when confronted with such information. We apply the basic principles of physics to a situation described in work of literature while making no attempt to validate or refute any philosophy, theology or ideology.
THE GOULD'S BELT DISTANCE SURVEY
Directory of Open Access Journals (Sweden)
L. Loinard
2011-01-01
Full Text Available Observaciones que utilizan la interferometría de muy larga línea de base (VLBI por sus siglas en ingl´es pueden proveer la posición de radiofuentes compactas con una precisión del orden de 50 micro-segundos de arco. Esto es suficiente para medir la paralaje trigonométrica y los movimientos propios de cualquier objeto localizado hasta 500 pc del Sol con una precisión mejor que unos porcientos. Por ser magnéticamente activas, las estrellas jóvenes a menudo emiten emisión radio compacta detectable usando técnicas VLBI. Aquí, mostraremos cómo observaciones VLBI ya han restringido la distancia a las regiones de formación estelar cercanas más frecuentemente estudiadas (Tauro, Ofiuco, Orión, etc. y han empezado a revelar su estructura y su cinemática interna. Luego, describiremos un gran proyecto (llamado The Gould's Belt Distance Survey diseñado para proveer una vista detallada de la formación estelar en la vecindad Solar, usando observaciones VLBI.
Giant Sparks at Cosmological Distances?
Kulkarni, S R; Neill, J D; Zheng, Z; Juric, M
2014-01-01
[Abridged] Millisecond duration bright radio pulses in the 1.4-GHz band and with inferred dispersion measures (DM) well in excess of Galactic values have been reported by Lorimer et al. and Thornton et al.. The all-sky rate of these events is large, ~10^4 per day above ~1 Jy. To add to the mystery there now exists "Perytons'' -- also pulsed and dispersed sources but most certainly of local (artificial or atmospheric) origin. The suggested models now range from sources originating in the Earth's atmosphere, in stellar coronae, in other galaxies and at even cosmological distances. Using a series of physically motivated assumptions combined with the observed properties of these bursts, we explore possible constraints on sites or processes that can account for such high DMs. In our analysis, we focus on the first such reported event by Lorimer et al.: a 30 Jy, 5-ms duration burst with a dispersion measure of 375 cm^-3 pc and exhibiting a steep frequency-dependent pulse width (hereafter dubbed as the Sparker). Ass...
Right Distance or Right Presence?
Directory of Open Access Journals (Sweden)
Edmée Runtz-Christan
2011-05-01
Full Text Available At a time when experts confront each other in order to determine what is essential to knowledge and didactics, to the logic of intention or to the logic of competence, it is necessary to recall that the only thing that the teacher can transmit is the will to know. Neither teaching nor didactics allows the learner to economize in the transition to the act. It is only when the student has decided to learn that they will acquire the knowledge and skills to succeed. It is essential to stimulate the student to act, remembering that, to be viable, the pedagogic relationship must be inscribed within an ethical, institutional and relational system, avoiding dependence or indifference to any of these. How then to convey the will to know without manipulating the student by means of didactic, relational or institutional strategies? How could the presence of the teacher be used to enhance the process of learning? What distances should be respected in order to sustain interest?
Social learning across psychological distance.
Kalkstein, David A; Kleiman, Tali; Wakslak, Cheryl J; Liberman, Nira; Trope, Yaacov
2016-01-01
While those we learn from are often close to us, more and more our learning environments are shifting to include more distant and dissimilar others. The question we examine in 5 studies is how whom we learn from influences what we learn and how what we learn influences from whom we choose to learn it. In Study 1, we show that social learning, in and of itself, promotes higher level (more abstract) learning than does learning based on one's own direct experience. In Studies 2 and 3, we show that when people learn from and emulate others, they tend to do so at a higher level when learning from a distant model than from a near model. Studies 4 and 5 show that thinking about learning at a higher (compared to a lower) level leads individuals to expand the range of others that they will consider learning from. Study 6 shows that when given an actual choice, people prefer to learn low-level information from near sources and high-level information from distant sources. These results demonstrate a basic link between level of learning and psychological distance in social learning processes. PMID:26727663
Moore, Michael G., Ed.; Cozine, Geoffrey T., Ed.
This book brings together a selection of articles published in "The American Journal of Distance Education" that are related to Web-based delivery of distance education. Articles include: "Performance and Perceptions of Distance Learners in Cyberspace" (Peter Navarro and Judy Shoemaker); "Distance Education for Dentists: Improving the Quality of…
Open and Distance Learning Today. Routledge Studies in Distance Education Series.
Lockwood, Fred, Ed.
This book contains the following papers on open and distance learning today: "Preface" (Daniel); "Big Bang Theory in Distance Education" (Hawkridge); "Practical Agenda for Theorists of Distance Education" (Perraton); "Trends, Directions and Needs: A View from Developing Countries" (Koul); "American Distance Education" (Moore); "Creating the…
DEFF Research Database (Denmark)
Larsen, Gunvor Riber
distance is theoretically developed through theories of consumption, mobility and tourism motivation, based on an understanding of distance as both a physical and relative phenomenon. This conceptualisation of consumption of distance is then applied to an inquiry of whether and how 30 Danish tourists...... consume distance when they travel on holiday. The conclusion of the research is that some tourists do, sometimes, consume distance when they travel on holiday, and that this happens when distance is integrated into their holiday mobility as symbolically, as experience or as motivation. This research...... establishes how tourists understand distance as phenomenon, which differs from the way distance is often conceptualised in academic studies of how distance influences travel behaviour. It identifies distance as a significant attraction in its own right for tourists and as a motivator for their holidays...
Microstructural Abnormalities of Short-Distance White Matter Tracts in Autism Spectrum Disorder
Shukla, Dinesh K.; Keehn, Brandon; Smylie, Daren M.; Muller, Ralph-Axel
2011-01-01
Recent functional connectivity magnetic resonance imaging and diffusion tensor imaging (DTI) studies have suggested atypical functional connectivity and reduced integrity of long-distance white matter fibers in autism spectrum disorder (ASD). However, evidence for short-distance white matter fibers is still limited, despite some speculation of…
Use and Perceptions of Second Life by Distance Learners: A Comparison with Other Communication Media
Murray, Jo-Anne; Littleton, Fiona; Dozier, Marshall
2015-01-01
Research has shown that the use of communication media in distance education can reduce feelings of distance and isolation from peers and tutors and provide opportunities for collaborative learning (Bates, 2005). The use of virtual worlds (VW) in education has increased in recent years, with Second Life (SL) being the most commonly used VW in…
Giant sparks at cosmological distances?
Energy Technology Data Exchange (ETDEWEB)
Kulkarni, S. R. [Caltech Optical Observatories 249-17, California Institute of Technology, Pasadena, CA 91125 (United States); Ofek, E. O. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Neill, J. D. [Space Radiation Laboratory 290-17, California Institute of Technology, Pasadena, CA 91125 (United States); Zheng, Z. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112 (United States); Juric, M. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
2014-12-10
Millisecond-duration bright radio pulses at 1.4 GHz with high dispersion measures (DMs) were reported by Lorimer et al., Keane et al., and Thornton et al. Their all-sky rate is ≈10{sup 4} day{sup –1} above ∼1 Jy. Related events are 'Perytons'–similar pulsed, dispersed sources, but most certainly local. Suggested models of fast radio bursts (FRBs) can originate in Earth's atmosphere, in stellar coronae, in other galaxies, and even at cosmological distances. Using physically motivated assumptions combined with observed properties, we explore these models. In our analysis, we focus on the Lorimer event: a 30 Jy, 5 ms duration burst with DM = 375 cm{sup –3} pc, exhibiting a steep frequency-dependent pulse width (the Sparker). To be complete, we drop the assumption that high DMs are produced by plasma propagation and assume that the source produces pulses with frequency-dependent arrival time ('chirped signals'). Within this framework, we explore a scenario in which Perytons, the Sparker, and the FRBs are all atmospheric phenomena occurring at different heights. This model is ad hoc in that we cannot explain why Perytons at higher altitudes show greater DMs or exhibit narrower pulses. Nonetheless, we argue that the Sparker may be a Peryton. We end with two remarks. First, the detection of a single FRB by an interferometer with a kilometer (or longer) baseline will prove that FRBs are of extraterrestrial origin. Second, we urge astronomers to pursue observations and understanding of Perytons since they form (at least) a formidable foreground for the FRBs.
Distance and Cable Length Measurement System
Hernández, Sergio Elias; Acosta, Leopoldo; Toledo, Jonay
2009-01-01
A simple, economic and successful design for distance and cable length detection is presented. The measurement system is based on the continuous repetition of a pulse that endlessly travels along the distance to be detected. There is a pulse repeater at both ends of the distance or cable to be measured. The endless repetition of the pulse generates a frequency that varies almost inversely with the distance to be measured. The resolution and distance or cable length range could be adjusted by varying the repetition time delay introduced at both ends and the measurement time. With this design a distance can be measured with centimeter resolution using electronic system with microsecond resolution, simplifying classical time of flight designs which require electronics with picosecond resolution. This design was also applied to position measurement. PMID:22303169
Testing Distance Estimators with the Fundamental Manifold
Zaritsky, Dennis; Gonzalez, Anthony H
2012-01-01
We demonstrate how the Fundamental Manifold (FM) can be used to cross-calibrate distance estimators even when those "standard candles" are not found in the same galaxy. Such an approach greatly increases the number of distance measurements that can be utilized to check for systematic distance errors and the types of estimators that can be compared. Here we compare distances obtained using SN Ia, Cepheids, surface brightness fluctuations, the luminosity of the tip of the red giant branch, circumnuclear masers, eclipsing binaries, RR Lyrae stars, and the planetary nebulae luminosity functions. We find no significant discrepancies (differences are < 2 sigma) between distance methods, although differences at the ~10% level cannot yet be ruled out. The potential exists for significant refinement because the data used here are heterogeneous B-band magnitudes that will soon be supplanted by homogeneous, near-IR magnitudes. We illustrate the use of FM distances to 1) revisit the question of the metallicity sensiti...
Quadratic distances on probabilities: A unified foundation
Lindsay, Bruce G.; Markatou, Marianthi; Ray, Surajit; Yang, Ke; Chen, Shu-Chuan
2008-01-01
This work builds a unified framework for the study of quadratic form distance measures as they are used in assessing the goodness of fit of models. Many important procedures have this structure, but the theory for these methods is dispersed and incomplete. Central to the statistical analysis of these distances is the spectral decomposition of the kernel that generates the distance. We show how this determines the limiting distribution of natural goodness-of-fit tests. Additionally, we develop...
LEARNING AT A DISTANCE WITH MOBILE PHONE
Khoo Yin Yin; Noor Al-Huda Abdul Karim; Norasibah Abdul Jalil
2015-01-01
This purpose of the study is to examine the effects of mobile learning with Quick Response Code (QR code) to promote distance learners’ motivation towards the Principles of Economics. This mobile learning with QR code allowed the distance learners to learn and communicate anytime and anywhere with their peers and lecturers. A survey method was employed in this study. A set of 25 items questionnaire constructed by the researcher was used as an instrument for the study. A total of 152 distance ...
Edit Distance between Unlabeled Ordered Trees
Micheli, Anne; Rossin, Dominique
2005-01-01
There exists a bijection between one stack sortable permutations --permutations which avoid the pattern $231$-- and planar trees. We define an edit distance between permutations which is coherent with the standard edit distance between trees. This one-to-one correspondence yields a polynomial algorithm for the subpermutation problem for $(231)$ avoiding permutations. Moreover, we obtain the generating function of the edit distance between ordered trees and some special ones. For the general c...
REVIEW: Distance Nurse Education (Uzaktan Hemsirelik Egitimi)
KURUBACAK, Reviewed By Gulsun; BOZ, Belgin
2011-01-01
Distance Nurse Education is the first book in the Turkish literature. The main purpose of this book is to introduce and discuss the dimensions, components and characteristics of Distance Nurse Education. The unique approach of this publication brings together 1) Distance Education, 2) Nurse Education, and 3) ALINE (Active Learning in Nursing Education) Model (Fay, Selz, and Johnson, 2005) together at the same time. This book focuses on the learning activities, learner-centered approach, inter...
DISTANCE NURSE EDUCATION (UZAKTAN HEMSIRELIK EGITIMI)
Gulsun KURUBACAK; BOZ, Belgin
2011-01-01
Distance Nurse Education is the first book in the Turkish literature. The main purpose of this book is to introduce and discuss the dimensions, components and characteristics of Distance Nurse Education. The unique approach of this publication brings together 1) Distance Education, 2) Nurse Education, and 3) ALINE (Active Learning in Nursing Education) Model (Fay, Selz, and Johnson, 2005) together at the same time. This book focuses on the learning activities, learner-centered approach, inter...
Long-distance calls in Neotropical primates
Oliveira Dilmar A.G.; Ades César
2004-01-01
Long-distance calls are widespread among primates. Several studies concentrate on such calls in just one or in few species, while few studies have treated more general trends within the order. The common features that usually characterize these vocalizations are related to long-distance propagation of sounds. The proposed functions of primate long-distance calls can be divided into extragroup and intragroup ones. Extragroup functions relate to mate defense, mate attraction or resource defense...
Federated Technologies for Distance Education - SINED (Mexico)
Cebrián de la Serna, Manuel; Galeana, Lourdes; Murrillo, Georgette
2013-01-01
The Association for the Development of the National Distance Education (SINED, https://www.sined.mx/sined/) is an organization which manages and develops distance education in Mexico. Its public and institutional actions are carried out through networking. Knowledge management is promoted through educational social networking supported by the strategic use of technology. SINED has contributed in various ways to the development of distance education in Mexico, e.g. through a) insta...
Distance Learning: The Case of Political Science
Steffen Schmidt; Mark C. Shelley; Monty Van Wart; Jane Clayton; Erin Schreck
2000-01-01
This article reports the results from a national survey directed to the department chairs of political science to assess the current and future state of distance learning in that discipline. The insights of this research are relevant to all social science fields and offer important insights to other academic disciplines as well. Key findings of the study include the low utilization of distance learning courses, a low degree of importance currently attributed to distance learning and modest ex...
THE IMPORTANCE OF DISTANCE EDUCATION IN NURSING
BOZ YUKSEKDAG, Belgin
2015-01-01
Nursing that the reason of its essence arises from social requirements is a practical discipline. It requires knowledge and skills. This knowledge and skills must be updated with developments in the health field. However, because of their living conditions, nurses cannot continue the formal education. Distance nursing programs provide flexibility to them. In this study will be handed the importance of distance education for nursing and the attitudes of nurses towards distance nursing programs.
A Gentle Introduction to the Kernel Distance
Phillips, Jeff M.; Venkatasubramanian, Suresh
2011-01-01
This document reviews the definition of the kernel distance, providing a gentle introduction tailored to a reader with background in theoretical computer science, but limited exposure to technology more common to machine learning, functional analysis and geometric measure theory. The key aspect of the kernel distance developed here is its interpretation as an L_2 distance between probability measures or various shapes (e.g. point sets, curves, surfaces) embedded in a vector space (specificall...
On the computation of edit distance functions
Martin, Ryan R.
2010-01-01
The edit distance between two graphs on the same labeled vertex set is the size of the symmetric difference of the edge sets. The edit distance function of the hereditary property, $\\mathcal{H}$, is a function of $p\\in[0,1]$ and is the limit of the maximum normalized distance between a graph of density $p$ and $\\mathcal{H}$. This paper uses the symmetrization method of Sidorenko in order to compute the edit distance function of various hereditary properties. For any graph $H$, ${\\rm Forb}(H)$...
Direct Distance Measurements to SN2009ip
Potashov, M; Baklanov, P; Dolgov, A
2013-01-01
We show applicability of our new method, Dense Shell Method (DSM), for measuring astronomical distances using an example of supernova SN2009ip, which had several outbursts. The method is based on the original Baade idea. Distance to this supernova is well measured via Cosmic Distance Ladder and generally assumed to be 20.4 Mpc. Our method directly gives a very close result, namely we find that the median distance is 20.1+/-0.8 (68% CL) Mpc to SN2009ip assuming the most reasonable values for its parameters.
Distance Learning: The Case of Political Science
Directory of Open Access Journals (Sweden)
Steffen Schmidt
2000-06-01
Full Text Available This article reports the results from a national survey directed to the department chairs of political science to assess the current and future state of distance learning in that discipline. The insights of this research are relevant to all social science fields and offer important insights to other academic disciplines as well. Key findings of the study include the low utilization of distance learning courses, a low degree of importance currently attributed to distance learning and modest expectations of future growth, ambivalent acceptance of a future role for distance learning, the common use of Internet-related technologies, low levels of faculty knowledge and interest about distance learning, limited institutional support, and serious doubts about the appropriateness and quality of instruction at a distance. We propose a model of the size and scope of distance learning as a function of three factors: the capacity of distance learning technologies, market demand, and faculty and university interest in distance learning. The article concludes with suggestions of critical areas for future research in this dynamic, fluid post-secondary environment.
Numerical distance protection principles and applications
Ziegler, Gerhard
2008-01-01
Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. Initially this book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is then placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a refere
New bounds for the distance Ramsey number
Kupavskii, Andrey; Raigorodskii, Andrei; Titova, Maria
2013-01-01
In this paper we study the distance Ramsey number $R_{{\\it D}}(s,t,d)$. The \\textit{distance Ramsey number} $R_{{\\it D}}(s,t,d) $ is the minimum number $n$ such that for any graph $ G $ on $ n $ vertices, either $G$ contains an induced $ s $-vertex subgraph isomorphic to a distance graph in $ \\Real^d $ or $ \\bar {G} $ contains an induced $ t $-vertex subgraph isomorphic to the distance graph in $ \\Real^d $. We obtain the upper and lower bounds on $R_{{\\it D}}(s,s,d),$ which are similar to the...
Mahalanobis Distance Based Iterative Closest Point
DEFF Research Database (Denmark)
Hansen, Mads Fogtmann; Blas, Morten Rufus; Larsen, Rasmus
2007-01-01
This paper proposes an extension to the standard iterative closest point method (ICP). In contrast to ICP, our approach (ICP-M) uses the Mahalanobis distance to align a set of shapes thus assigning an anisotropic independent Gaussian noise to each point in the reference shape. The paper introduces...... the notion of a mahalanobis distance map upon a point set with associated covariance matrices which in addition to providing correlation weighted distance implicitly provides a method for assigning correspondence during alignment. This distance map provides an easy formulation of the ICP problem that...
Angular Diameter Distances in Clumpy Friedmann Universes
Tomita, K
1998-01-01
Solving null-geodesic equations, behavior of angular diameter distances is studied in inhomogeneous cosmological models, which are given by performing N-body simulations with the CDM spectrum. The distances depend on the separation angle of ray pairs, the mass and the radius of particles cosisting of galaxies and dark matter balls, and cosmological model parameters. The calculated distances are compared with the Dyer- Roeder distance, and after many ray-shooting, the average, dispersion and distribution of the clumpiness parameter are derived.
Distance based (DBCP) Cluster Protocol for Heterogeneous Wireless Sensor Network
Kumar, Surender; Prateek, Manish; Bhushan, Bharat
2014-01-01
Clustering is an important concept to reduce the energy consumption and prolonging the life of a wireless sensor network. In heterogeneous wireless sensor network some of the nodes are equipped with more energy than the other nodes. Many routing algorithms are proposed for heterogeneous wireless sensor network. Stable Election Protocol (SEP) is one of the important protocol in this category. In this research paper a novel energy efficient distance based cluster protocol (DBCP) is proposed for...
Speed trends in male distance running.
Kruse, Timothy N; Carter, Rickey E; Rosedahl, Jordan K; Joyner, Michael J
2014-01-01
The major cycling "Grand Tours" have shown an attenuation of performance over the last decade. This has been interpreted as circumstantial evidence that newer anti-doping strategies have reduced the use of performance-enhancing drugs. To examine this idea under more controlled conditions, speed trends for world class 5000 m, 10000 m, and marathon performances by men from 1980 to 2013 were analyzed. We obtained comprehensive records from the International Association of Athletics Federations, Association of Road Racing Statisticians, and the Track and Field All-time Performances database webpages. The top 40 performances for each event and year were selected for regression analysis. For the three distances, we noted cumulative performance improvements in the 1990s thru the mid-2000s. After the peak speed years of the mid 2000 s, there has been limited improvement in the 5000 m and 10,000 m and world records set during that time remain in place today, marking the longest period of time between new records since the early 1940s. By contrast marathon speed continues to increase and the world record has been lowered four times since 2007, including in 2013. While the speed trends for 5000 m and 10000 m track results parallel those seen in elite cycling, the marathon trends do not. We discuss a number of explanations other than improved anti-doping strategies that might account for these divergent findings. PMID:25409192
Speed trends in male distance running.
Directory of Open Access Journals (Sweden)
Timothy N Kruse
Full Text Available The major cycling "Grand Tours" have shown an attenuation of performance over the last decade. This has been interpreted as circumstantial evidence that newer anti-doping strategies have reduced the use of performance-enhancing drugs. To examine this idea under more controlled conditions, speed trends for world class 5000 m, 10000 m, and marathon performances by men from 1980 to 2013 were analyzed. We obtained comprehensive records from the International Association of Athletics Federations, Association of Road Racing Statisticians, and the Track and Field All-time Performances database webpages. The top 40 performances for each event and year were selected for regression analysis. For the three distances, we noted cumulative performance improvements in the 1990s thru the mid-2000s. After the peak speed years of the mid 2000 s, there has been limited improvement in the 5000 m and 10,000 m and world records set during that time remain in place today, marking the longest period of time between new records since the early 1940s. By contrast marathon speed continues to increase and the world record has been lowered four times since 2007, including in 2013. While the speed trends for 5000 m and 10000 m track results parallel those seen in elite cycling, the marathon trends do not. We discuss a number of explanations other than improved anti-doping strategies that might account for these divergent findings.
Energy Technology Data Exchange (ETDEWEB)
Su, Chuan-Qi; Gao, Yi-Tian; Yu, Xin [Beijing Univ. of Aeronautics and Astronautics (China). Ministry-of-Education Key Lab. of Fluid Mechanics and National Lab. for Computational Fluid Dynamics; Xue, Long [Beijing Univ. of Aeronautics and Astronautics (China). Ministry-of-Education Key Lab. of Fluid Mechanics and National Lab. for Computational Fluid Dynamics; Aviation Univ. of Air Force, Liaoning (China). Flight Training Base
2015-07-01
Under investigation in this article is a higher-order nonlinear Schroedinger-Maxwell-Bloch (HNLS-MB) system for the optical pulse propagation in an erbium-doped fiber. Lax pair, Darboux transformation (DT), and generalised DT for the HNLS-MB system are constructed. Soliton solutions and rogue wave solutions are derived based on the DT and generalised DT, respectively. Properties of the solitons and rogue waves are graphically presented. The third-order dispersion parameter, fourth-order dispersion parameter, and frequency detuning all influence the characteristic lines and velocities of the solitons. The frequency detuning also affects the amplitudes of solitons. The separating function has no effect on the properties of the first-order rogue waves, except for the locations where the first-order rogue waves appear. The third-order dispersion parameter affects the propagation directions and shapes of the rogue waves. The frequency detuning influences the rogue-wave types of the module for the measure of polarization of resonant medium and the extant population inversion. The fourth-order dispersion parameter impacts the rogue-wave interaction range and also has an effect on the rogue-wave type of the extant population inversion. The value of separating function affects the spatial-temporal separation of constituting elementary rogue waves for the second-order and third-order rogue waves. The second-order and third-order rogue waves can exhibit the triangular and pentagon patterns under different choices of separating functions.
International Nuclear Information System (INIS)
Under investigation in this article is a higher-order nonlinear Schroedinger-Maxwell-Bloch (HNLS-MB) system for the optical pulse propagation in an erbium-doped fiber. Lax pair, Darboux transformation (DT), and generalised DT for the HNLS-MB system are constructed. Soliton solutions and rogue wave solutions are derived based on the DT and generalised DT, respectively. Properties of the solitons and rogue waves are graphically presented. The third-order dispersion parameter, fourth-order dispersion parameter, and frequency detuning all influence the characteristic lines and velocities of the solitons. The frequency detuning also affects the amplitudes of solitons. The separating function has no effect on the properties of the first-order rogue waves, except for the locations where the first-order rogue waves appear. The third-order dispersion parameter affects the propagation directions and shapes of the rogue waves. The frequency detuning influences the rogue-wave types of the module for the measure of polarization of resonant medium and the extant population inversion. The fourth-order dispersion parameter impacts the rogue-wave interaction range and also has an effect on the rogue-wave type of the extant population inversion. The value of separating function affects the spatial-temporal separation of constituting elementary rogue waves for the second-order and third-order rogue waves. The second-order and third-order rogue waves can exhibit the triangular and pentagon patterns under different choices of separating functions.
Directory of Open Access Journals (Sweden)
Latif Taşkaya
2016-03-01
Full Text Available In this study, quality properties and shelf life for gibel carp (Carassius gibelio, Bloch 1782 marinades during stored at 4±1 °C in different sauces was investigated. The marinating process was carried out in 2.5% vinegar, 10% salt and water for 72h at 4±1 °C. After the marination process, fish were removed from the solutions, transferred in to glass jar contain with different sauces (Group A: sunflower oil and tomato paste, Group B: sunflower oil with garlic, red pepper, thyme, basil and mint and the control group: sun flower oil. Sensory, chemical, colour and microbiological analyses were performed during the storage. According the chemical analysis results TVB-N and TBA values of all groups were increased during the storage, but during the stored period did not exceed acceptible limit values. The highest TVB-N and TBA values were group A. (P<0,05. At the end of 135 days of storage, sensory analysis results pointed out that the marinades of group B did not exceed acceptible limit values (P<0,05. The overall microbial load of the fresh samples decreased through out the storage period (P<0,05. By sensory data, shelf life of sauced gibel carp marinades were 120 days (control, 105 days (group A and 135 days (group B.
Xie, Xi-Yang; Tian, Bo; Sun, Wen-Rong; Sun, Ya; Liu, De-Yin
2015-10-01
In this paper, we construct soliton solutions for a generalized variable-coefficient coupled Hirota-Maxwell-Bloch system, which can describe the ultrashort optical pulse propagation in a nonlinear, dispersive fiber doped with two-level resonant atoms. Under certain transformations and constraints, one- and two-soliton solutions are obtained via the Hirota method and symbolic computation, and soliton collisions are graphically presented and analyzed. One soliton is shown to maintain its amplitude and shape during the propagation. Soliton collision is elastic, while bright two-peak solitons and dark two-peak solitons are also observed. We discuss the influence of the coefficients for the group velocity, group-velocity dispersion (GVD), self-phase modulation, distribution of the dopant, and Stark shift on the soliton propagation and collision features, with those coefficients are set as some constants and functions, respectively. We find the group velocity and self-phase modulation can change the solitons' amplitudes and widths, and the solitons become curved when the GVD and distribution of the dopant are chosen as some functions. When the Stark shift is chosen as a certain constant, the two peaks of bright two-peak solitons and dark two-peak solitons are not parallel. In addition, we observe the periodic collision of the two solitons.