Mechanism of metallization and superconductivity suppression in YBa2(_2(Cu0.97_{0.97}Zn0.03)3_{0.03})_3O6.92_{6.92} revealed by 67^{67}Zn NQR

We measure the nuclear quadrupole resonance (NQR) signal on the Zn site in nearly optimally doped YBa$_2$Cu$_3$O$_{6.92}$, when Cu is substituted by 3\% of isotopically pure $^{67}$Zn. We observe that Zn creates large insulating islands, confirming two earlier conjectures: that doping provokes an orbital transition in the CuO$_2$ plane, which is locally reversed by Zn substitution, and that the islands are antiferromagnetic. Also, we find that the Zn impurity locally induces a breaking of the D$_4$ symmetry. Cluster and DFT calculations show that the D$_4$ symmetry breaking is due to the same partial lifting of degeneracy of the nearest-neighbor oxygen sites as in the LTT transition in La$_{2-x}$Ba$_x$CuO$_4$, similarly well-known to strongly suppress superconductivity. These results show that in-plane oxygen $2p^5$ orbital configurations are principally involved in the metallicity and superconductivity of all high-T$_c$ cuprates, and provide a qualitative symmetry-based constraint on the SC mechanism.Comment: extended version, to appear in New Journal of Physic

The Management of Research and Development (Selected papers from a conference in Wroclaw, Poland, September 1978)

This paper is one of two IIASA Collaborative Papers containing papers presented at the Third International Conference on the Management of Research, Development and Education held at Wroclaw, Poland in September 1978. The conference was, on this occasion, jointly organized by Dr. Karol Pelc, Director of the Forecasting Research Center of the Technical University of Wroclaw and by Professor Gennady Dobrov, Deputy Director, Institute of Cybernetics, Kiev and at that time a member of the staff of the Management and Technology Area of the International Institute for Applied Systems Analysis. Formally, it was jointly sponsored by the Wroclaw Technical University and IIASA. It is always difficult to decide what to do about conference proceedings. The greatest value of such conferences is usually the meeting between minds -- the exchange of information and understanding between people from different cultures and academic backgrounds. This was particularly true at the Wroclaw conference where there was strong representation from ten countries, both East and West. It was a rare opportunity for scientists to identify potential collaborators and discover who was working in which field. Such opportunities are too few. Nevertheless, the Conference Scientific Committee felt that a number of the papers should be made available for reference in a more accessible form, and with their help, we have made a selection for issue as IIASA Collaborative Papers. A complete list of the 40 papers read at the conference are given as an Appendix to this collection -- copies of individual papers can be obtained by request from the Forecasting Research Center, Technical University of Wroclaw. The introductory paper to the conference was on "Main Problems in the Control of Scientific and Technological Creative Activities, Application of Innovations and Education of Scientific Staff" and was given by Professor Jan Kaczmarek, Scientific Secretary of the Polish Academy of Sciences and a member of the IIASA Council. We felt that this was of sufficient interest for a separate issue, and appears as IIASA CP-80-19. For the rest we have selected thirteen papers for issue in this volume, and have divided them into three groups. The first group of five papers is concerned with problems of strategic decision making in the field of science and technology. The first, by Petrasek, provides a new method of classifying the tasks in a forecasting problem which should help in improving the relevance of the results to real-life decisions. Baworowski emphasizes the importance of technology forecasting in developing a producers strategy, and the importance of matching the forecasting procedure to needs at all levels. Two papers, by Schulze and Pelc, are then concerned with the analysis of factors determining national strategy for science and development. Finally, we have a paper by Dierkes and Thienen which discusses the problems of getting a satisfactory debate over science policy issues, and considers the "Science Court" -- proposed originally by Kantrowitz -- as a possible solution. The next group of papers is concerned with structural changes in science and technology and their impact on the management of interdisciplinary research. The first of these is by Albrecht and Otto who discuss, on the basis of extensive historical studies, the dangers of generalizing over the science-technology-production cycle without making clear differentiation between different classes of technology, as well as other factors. Eto shows some of the problems arising from the development of new sciences -- both basic and mission oriented sciences -- and discusses the implications. Glowiak and Winnicki follow this theme in discussing the managerial action needed to stimulate new fields of technological expertise, such as environmental engineering. Finally, Dobrov, Randolph and Nurminski present some work undertaken at IIASA relating to technological change in agriculture, and in particular draw attention to the problems introduced by the rapidly decreasing output-input energy ratio. The third group of papers deals with broader questions of management of R&D and of technological change. Bobryshev and Chereshkin discuss, in particular, the development of a planned management information system for research and development in the USSR. Wasniowski considers four questions related to the management of long range programs, namely: What is a long range program? What are the problems of formulation and management? Why is technology assessment needed? Why is systems analysis needed? He discusses the use of computer conferencing and the use of gaming. Ball, Miller and Pearson then give a detailed study of the development of single cell protein, and pay particular attention to the problem of matching technology to market needs. Finally, Jermakowicz and Ruszkiewicz undertake a study of the machinery industry in Poland which enable them to identify some of the major organizational factors influencing the effectiveness of the Science-Technology-Production cycle in industrial enterprises. All the papers are presented here as given at the conference. In the interests of economy we have not attempted to edit them in any way. We would like to take this opportunity of thanking the members of the Scientific Committee of the conference for their help with regard to the conduct of the conference and the subsequent selection of papers for publication. It was another example of successful international collaboration

Energy-Based Plasmonicity Index to Characterize Optical Resonances in Nanostructures

Resonances sustained by plasmonic nanoparticles provide extreme electric field confinement and enhancement into the deep subwavelength domain for a plethora of applications. Recent progress in nanofabrication made it even possible to tailor the properties of nanoparticles consisting of only a few hundred atoms. These nanoparticles support both single-particle-like resonances and collective plasmonic charge density oscillations. Prototypical systems sustaining both features are graphene nanoantennas. In pushing the frontier of nanoscience, traditional identification, and classification of such resonances is at stake again. We show that in such nanostructures, the concerted electron cloud oscillation in real space does not necessarily come along with collective dynamics of conduction band electrons in energy space. This unveils an urgent need for a discussion of how a plasmon in nanostructures should be defined. Here, we propose to define it relying on energy space dynamics. The unambiguous identification of the plasmonic nature of a resonance is crucial to find out whether desirable plasmon-assisted features, such as frequency conversion processes, can be expected from a resonance. We elaborate an energy-based figure of merit that classifies the nature of resonances in nanostructures, motivated by tight binding simulations with a toy model consisting of a linear chain of atoms. We apply afterward the proposed figure of merit to a doped hexagonal graphene nanoantenna, which is known to support plasmons in the near infrared and single-particle-like transitions in the visible

Proper acceleration, geometric tachyon and dynamics of a fundamental string near Dpp branes

We present a detailed analysis of our recent observation that the origin of the geometric tachyon, which arises when a D$p$-brane propagates in the vicinity of a stack of coincident NS5-branes, is due to the proper acceleration generated by the background dilaton field. We show that when a fundamental string (F-string), described by the Nambu-Goto action, is moving in the background of a stack of coincident D$p$-branes, the geometric tachyon mode can also appear since the overall conformal mode of the induced metric for the string can act as a source for proper acceleration. We also studied the detailed dynamics of the F-string as well as the instability by mapping the Nambu-Goto action of the F-string to the tachyon effective action of the non-BPS D-string. We qualitatively argue that the condensation of the geometric tachyon is responsible for the (F,D$p$) bound state formation.Comment: 26 pages, v2: added references, v3: one ref. updated, to appear in Class. and Quant. Gravit

Non-Critical String Duals of N=1 Quiver Theories

We construct N=1 non-critical strings in four dimensions dual to strongly coupled N=1 quiver gauge theories in the Coulomb phase, generalizing the string duals of Argyres-Douglas points in N=2 gauge theories. They are the first examples of superstrings vacua with an exact worldsheet description dual to chiral N=1 theories. We identify the dual of the non-critical superstring using a brane setup describing the field theory in the classical limit. We analyze the spectrum of chiral operators in the strongly coupled regime and show how worldsheet instanton effects give non-perturbative information about the gauge theory. We also consider aspects of D-branes relevant for the holographic duality.Comment: JHEP style; 40 pages, 3 figures; v2: minor corrections, refs added, version to appear in JHE

Positive energy unitary irreducible representations of D=6 conformal supersymmetry

We give a constructive classification of the positive energy (lowest weight) unitary irreducible representations of the D=6 superconformal algebras osp(8*/2N). Our results confirm all but one of the conjectures of Minwalla (for N=1,2) on this classification. Our main tool is the explicit construction of the norms of the states that has to be checked for positivity. We give also the reduction of the exceptional UIRs.Comment: 27 pages, TeX with harvmac, amssym.def, amssym.tex; v.2: minor corrections and references added; v.3: minor corrections; v.4: to appear in J. Phys.

Low energy electron attachment to cyanamide (NH2CN)

Cyanamide (NH2CN) is a molecule relevant for interstellar chemistry and the chemical evolution of life. In the present investigation, dissociative electron attachment to NH2CN has been studied in a crossed electronmolecular beams experiment in the electron energy range from about 0 eV to 14 eV. The following anionic species were detected: NHCN-, NCN-, CN-, NH2-, NH-, and CH2-. The anion formation proceeds within two broad electron energy regions, one between about 0.5 and 4.5 eV and a second between 4.5 and 12 eV. A discussion of possible reaction channels for all measured negative ions is provided. The experimental results are compared with calculations of the thermochemical thresholds of the anions observed. For the dehydrogenated parent anion, we explain the deviation between the experimental appearance energy of the anion with the calculated corresponding reaction threshold by electron attachment to the isomeric form of NH2CN-carbodiimide(VLID)1020340Accepted versio

Recognition of Face Identity and Emotion in Expressive Specific Language Impairment

Objective: To study face and emotion recognition in children with mostly expressive specific language impairment (SLI-E). Subjects and Methods: A test movie to study perception and recognition of faces and mimic-gestural expression was applied to 24 children diagnosed as suffering from SLI-E and an age-matched control group of normally developing children. Results: Compared to a normal control group, the SLI-E children scored significantly worse in both the face and expression recognition tasks with a preponderant effect on emotion recognition. The performance of the SLI-E group could not be explained by reduced attention during the test session. Conclusion: We conclude that SLI-E is associated with a deficiency in decoding non-verbal emotional facial and gestural information, which might lead to profound and persistent problems in social interaction and development. Copyright (C) 2012 S. Karger AG, Base

Spectral compression of single photons

Photons are critical to quantum technologies since they can be used for virtually all quantum information tasks: in quantum metrology, as the information carrier in photonic quantum computation, as a mediator in hybrid systems, and to establish long distance networks. The physical characteristics of photons in these applications differ drastically; spectral bandwidths span 12 orders of magnitude from 50 THz for quantum-optical coherence tomography to 50 Hz for certain quantum memories. Combining these technologies requires coherent interfaces that reversibly map centre frequencies and bandwidths of photons to avoid excessive loss. Here we demonstrate bandwidth compression of single photons by a factor 40 and tunability over a range 70 times that bandwidth via sum-frequency generation with chirped laser pulses. This constitutes a time-to-frequency interface for light capable of converting time-bin to colour entanglement and enables ultrafast timing measurements. It is a step toward arbitrary waveform generation for single and entangled photons.Comment: 6 pages (4 figures) + 6 pages (3 figures

SL(2,R)/U(1) Supercoset and Elliptic Genera of Non-compact Calabi-Yau Manifolds

We first discuss the relationship between the SL(2;R)/U(1) supercoset and N=2 Liouville theory and make a precise correspondence between their representations. We shall show that the discrete unitary representations of SL(2;R)/U(1) theory correspond exactly to those massless representations of N=2 Liouville theory which are closed under modular transformations and studied in our previous work hep-th/0311141. It is known that toroidal partition functions of SL(2;R)/U(1) theory (2D Black Hole) contain two parts, continuous and discrete representations. The contribution of continuous representations is proportional to the space-time volume and is divergent in the infinite-volume limit while the part of discrete representations is volume-independent. In order to see clearly the contribution of discrete representations we consider elliptic genus which projects out the contributions of continuous representations: making use of the SL(2;R)/U(1), we compute elliptic genera for various non-compact space-times such as the conifold, ALE spaces, Calabi-Yau 3-folds with A_n singularities etc. We find that these elliptic genera in general have a complex modular property and are not Jacobi forms as opposed to the cases of compact Calabi-Yau manifolds.Comment: 39 pages, no figure; v2 references added, minor corrections; v3 typos corrected, to appear in JHEP; v4 typos corrected in eqs. (3.22) and (3.44