Electrostatic tailoring of magnetic interference in quantum point contact ballistic Josephson junctions

The magneto-electrostatic tailoring of the supercurrent in quantum point contact ballistic Josephson junctions is demonstrated. An etched InAs-based heterostructure is laterally contacted to superconducting niobium leads and the existence of two etched side gates permits, in combination with the application of a perpendicular magnetic field, to modify continuously the magnetic interference pattern by depleting the weak link. For wider junctions the supercurrent presents a Fraunhofer-like interference pattern with periodicity h/2e whereas by shrinking electrostatically the weak link, the periodicity evolves continuously to a monotonic decay. These devices represent novel tunable structures that might lead to the study of the elusive Majorana fermions.Comment: 4.5 pages, 4 color figure

Freedom and Complicity: The Case of Horison and Solidarity, two Congress for Cultural Freedom Journals in Southeast Asia

The current project is a two-pronged study of Horison (Indonesia) and Solidarity (Philippines), two journals funded by the Congress for Cultural Freedom (CCF) during the Cold War in its quest to mount a cultural offensive against the rising threat of communism in Southeast Asia. The first part of the project deals with what Ang Cheng Guan sees as the case of the Cold War ceasing to be an actual historical event and, in turn, transforming into an “object” of historical inquiry (1–17). To this end, the article will provide a short account of both journals’ genesis and history during the Cold War’s peak in the region. Through the use of computer-aided methods, the second part will attempt a “closer” reading of selected editorials from 1966 to 1976 in order to shed light on specific discursive-ideological aspects (i.e., anti-communist intimations) evinced by both journals and their progenitors

Growth cycles in Latin America and developed countries

The Minskyan approach to financial instability and its effects on the real economy have recently been revived in order to explain the exchange rate crises undergone by the so-called emergent economies. Economies of this type are characterized by repeated scarcity of foreign currency, which can be explained by using Neo-Schumpeterian theory. Based on the Minskyan approach and on the Neo-Schumpeterian literature, this study seeks to demonstrate that there is a cyclic recurrence of exchange rate crises in Latin-American (peripheral) economies. By using data on international liquidity, the balance of payments and the increase in production in the G7 economies and in thirteen Latin-American economies, it was found that the Latin-American economies mirror the cycles of international liquidity.financial instability, national innovation system, cycles

Circularly Polarized Resonant Rayleigh Scattering and Skyrmions in the ν\nu = 1 Quantum Hall Ferromagnet

We use the circularly polarized resonant Rayleigh scattering (RRS) to study the quantum Hall ferromagnet at $\nu$ = 1. At this filling factor we observe a right handed copolarized RRS which probes the Skyrmion spin texture of the electrons in the photoexcited grounds state. The resonant scattering is not present in the left handed copolarization, and this can be related to the correlation between Skymionic effects, screening and spin wave excitations. These results evidence that RRS is a valid method for the study of the spin texture of the quantum Hall states

An attractive nucleon-nucleon spin-orbit force from skyrmions with dilatons

Within the skyrmion approach for the nucleon-nucleon force, difficulties have been experienced in obtaining an isoscalar attractive spin-orbit potential, in parallel to the problems of finding attraction in the isoscalar central potential. We here study the spin-orbit force using a skyrmion with four- and six-derivative stabilizing terms in the lagrangian as well as with the crucial addition of a dilaton. With these features present the spin-orbit force proves to be attractive as does the central potential. In the absence of the dilaton, attraction can also be found for the spin-orbit potential but only at the expense of a greatly over-emphasized term with six derivatives and a continuing absence of attraction in the central potential.Comment: 8 pages plus 5 figures in uuencoded tar-compressed for

A study of local approximation for polarization potentials

We discuss the derivation of an equivalent \textit{l}-independent polarization potential for use in the optical Schr\"{o}dinger equation that describes the elastic scattering of heavy ions. Three diffferent methods are used for this purpose. Application of our theory to the low energy scattering of the halo nucleus $^{11}$Li from a $^{12}$C target is made. It is found that the notion of \textit{l}-independent polarization potential has some validity but can not be a good substitute for the \textit{l}-dependent local equivalent Feshbach polarization potential.Comment: 8 pages, 4 figure

High-cadence spectroscopy of M-dwarfs – II. Searching for stellar pulsations with HARPS

Stellar oscillations appear all across the Hertzsprung–Russell diagram. Recent theoretical studies support their existence also in the atmosphere of M dwarfs. These studies predict for them short periodicities ranging from 20 min to 3 h. Our Cool Tiny Beats (CTB) programme aims at finding these oscillations for the very first time. With this goal, CTB explores the short time domain of M dwarfs using radial velocity data from the High Accuracy Radial velocity Planet Searcher (HARPS)-European Southern Observatory and HARPS-N high-precision spectrographs. Here we present the results for the two most long-term stable targets observed to date with CTB, GJ 588 and GJ 699 (i.e. Barnard's star). In the first part of this work we detail the correction of several instrumental effects. These corrections are especially relevant when searching for subnight signals. Results show no significant signals in the range where M dwarfs pulsations were predicted. However, we estimate that stellar pulsations with amplitudes larger than ∼0.5 m s−1 can be detected with a 90 per cent completeness with our observations. This result, along with the excess of power regions detected in the periodograms, opens the possibility of non-resolved very low amplitude pulsation signals. Next generation more precise instrumentation would be required to detect such oscillations. However, the possibility of detecting pulsating M-dwarf stars with larger amplitudes is feasible due to the short size of the analysed sample. This motivates the need for completeness of the CTB survey

Algebraic-eikonal approach to medium energy proton scattering from odd-mass nuclei

We extend the algebraic-eikonal approach to medium energy proton scattering from odd-mass nuclei by combining the eikonal approximation for the scattering with a description of odd-mass nuclei in terms of the interacting boson-fermion model. We derive closed expressions for the transition matrix elements for one of the dynamical symmetries and discuss the interplay between collective and single-particle degrees of freedom in an application to elastic and inelastic proton scattering from $^{195}$Pt.Comment: latex, 14 pages, 4 figures uuencoded, to be published in Physical Review

Two are better than one: Volatility forecasting using multiplicative component GARCH‐MIDAS models

We examine the properties and forecast performance of multiplicative volatility specifications that belong to the class of generalized autoregressive conditional heteroskedasticity–mixed-data sampling (GARCH-MIDAS) models suggested in Engle, Ghysels, and Sohn (Review of Economics and Statistics, 2013, 95, 776–797). In those models volatility is decomposed into a short-term GARCH component and a long-term component that is driven by an explanatory variable. We derive the kurtosis of returns, the autocorrelation function of squared returns, and the R2 of a Mincer–Zarnowitz regression and evaluate the QMLE and forecast performance of these models in a Monte Carlo simulation. For S&P 500 data, we compare the forecast performance of GARCH-MIDAS models with a wide range of competitor models such as HAR (heterogeneous autoregression), realized GARCH, HEAVY (high-frequency-based volatility) and Markov-switching GARCH. Our results show that the GARCH-MIDAS based on housing starts as an explanatory variable significantly outperforms all competitor models at forecast horizons of 2 and 3 months ahead