Vortex-glass transition in superconducting Nb/Cu superlattices

Nb/Cu superconducting superlattices have been fabricated by dc magnetron sputtering. This system shows a vortex glass transition with critical exponents similar to high temperatures superconductors exponents. The transition dymensionality is governed by the superconducting coupling regime. The vortex glass transition shows a pure two dimensional behavior in decoupled superlattices and a quasi-two dimensional behavior in the superlattice coupling regime.Comment: 9 pages, 3 figure

Optical-fiber source of polarization-entangled photon pairs in the 1550nm telecom band

We present a fiber based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1550nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally-polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal-idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal-idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either the signal or the idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of CHSH form of Bell's inequalities by up to 10 standard deviations of measurement uncertainty.Comment: 12 pages, 4 figures, to be submitted to Phys. Rev. Lett. See also paper QTuB4 in QELS'03 Technical Digest (OSA, Washington, D.C., 2003). This is a more complete versio

The Corona Truth Wars:Epistemic Disputes and Societal Conflicts around a Pandemic—An Introduction to the Special Issue

Ever since the start of the Corona pandemic, different and often conflicting views have emerged about the virus and how to appropriately deal with it. Such epistemic, societal, and economic criticisms, including those about government imposed measures, have often been dismissed as dangerous forms of conspiratorial disinformation that should be (and have been) excluded from the realm of reasonable political discussion. However, since these critiques of emerging hegemonic knowledge and policies often involve significant and complex questioning of epistemic and political claims, and since corresponding plausibilities change over time, such clear distinctions between correct knowledge and foolish, fraudulent, and/or dangerous, disinformation are not easy to draw. In fact, they can be considered political acts in these epistemic disputes over the pandemic. These conflicts, which we refer to as the “Corona Truth Wars,” are not just about knowledge, but have turned into societal conflicts and even outright identity wars that run through families, circles of friends, organizations, and entire societies. In this special issue, we illuminate these dynamics by bringing together a range of scholars who have been struck by the complexity of these controversies and their far-reaching social consequences. Far from understanding these controversies as simple dichotomies between truth and disinformation, or between disinterested science and manipulative politics, these scholars are interested in the various ways in which these dimensions are intertwined. Building on a long tradition of exploring (scientific) knowledge controversies, the six contributions to this special issue show how epistemic struggles over truth are not only fought in the realm of science, but increasingly manifest and interact in everyday politics, social media platforms, daily talk shows, and family dinners. The scholars brought together in this issue, with diverse disciplinary backgrounds and from different geographical regions (Denmark, France, Germany, the Czech Republic, and Israel), present their studies on the various epistemic and social conflicts that have emerged during the Corona pandemic of the last three years.</p

Ion and electron temperatures in the SUMMA mirror device by emission spectroscopy

Ion and electron temperatures, and ion drift were measured in a superconducting magnetic mirror apparatus by observing the Doppler-broadened charge-exchange component of the 667.8 and 587.6 nanometer He lines in He plasma, and the H sub alpha and H sub beta lines in H2 plasma. The second moment of the line profiles was used as the parameter for determining ion temperature. Corrections for magnetic splitting, fine structure, monochromator slit function, and variation in charge-exchange cross section with energy are included. Electron temperatures were measured by the line ratio method for the corona model, and correlations of ion and electron temperatures with plasma parameters are presented

Aluminium-oxide wires for superconducting high kinetic inductance circuits

We investigate thin films of conducting aluminium-oxide, also known as granular aluminium, as a material for superconducting high quality, high kinetic inductance circuits. The films are deposited by an optimised reactive DC magnetron sputter process and characterised using microwave measurement techniques at milli-Kelvin temperatures. We show that, by precise control of the reactive sputter conditions, a high room temperature sheet resistance and therefore high kinetic inductance at low temperatures can be obtained. For a coplanar waveguide resonator with 1.5\,k$\Omega$ sheet resistance and a kinetic inductance fraction close to unity, we measure a quality factor in the order of 700\,000 at 20\,mK. Furthermore, we observe a sheet resistance reduction by gentle heat treatment in air. This behaviour is exploited to study the kinetic inductance change using the microwave response of a coplanar wave guide resonator. We find the correlation between the kinetic inductance and the sheet resistance to be in good agreement with theoretical expectations.Comment: 16 pages, 7 figure

Layer Features of the Lattice Gas Model for Self-Organized Criticality

A layer-by-layer description of the asymmetric lattice gas model for 1/f-noise suggested by Jensen [Phys. Rev. Lett. 64, 3103 (1990)] is presented. The power spectra of the lattice layers in the direction perpendicular to the particle flux is studied in order to understand how the white noise at the input boundary evolves, on the average, into 1/f-noise for the system. The effects of high boundary drive and uniform driving force on the power spectrum of the total number of diffusing particles are considered. In the case of nearest-neighbor particle interactions, high statistics simulation results show that the power spectra of single lattice layers are characterized by different $\beta_x$ exponents such that $\beta_x \to 1.9$ as one approaches the outer boundary.Comment: LaTeX, figures upon reques

A bargaining and property rights perspective on the Belt and Road Initiative: Cases from the Italian port system

Infrastructural assets are vital for a country’s economic and social development. Governments typically provide the regulation and administration of these assets, while multinational enterprises (MNEs) develop, construct, finance, and operate them. The Belt and Road Initiative (BRI) promises infrastructure projects that deliver economic and social benefit for both the host country and the MNE, however, the foreign market entry activities of Chinese MNEs in infrastructure projects might not always be successful. By bridging the bargaining power literature with the economics of property rights perspective, we examine how and why host-country actors at different governance levels influence foreign direct investment. Using a comparative case study approach, we interrogate four attempts by Chinese firms to negotiate access to Italian ports. In particular, we show that for a BRI port investment to take place, there has to be an alignment between the various actors of the property rights nexus regarding the allocation of rights. Chinese investors need to understand the bargaining position and property rights of actors across multiple levels, across space, and be mindful of changes over time when negotiating an infrastructure investment. Host-country governments need to have a clear port infrastructure strategy to avoid wasting resources in lengthy negotiations and useless infrastructure

Effects of Middle-Ear Disorders on Power Reflectance Measured in Cadaveric Ear Canals

Objective: Reflectance measured in the ear canal offers a noninvasive method to monitor the acoustic properties of the middle ear, and few systematic measurements exist on the effects of various middleear disorders on the reflectance. This work uses a human cadaver-ear preparation and a mathematical middle-ear model to both measure and predict how power reflectance R is affected by the middle-ear disorders of static middle-ear pressures, middle-ear fluid, fixed stapes, disarticulated incudostapedial joint, and tympanic-membrane perforations. Design: R was calculated from ear-canal pressure measurements made on human-cadaver ears in the normal condition and five states: (1) positive and negative pressure in the middle-ear cavity, (2) fluidfilled middle ear, (3) stapes fixed with dental cement, (4) incudostapedial joint disarticulated, and (5) tympanic-membrane perforations. The middle-ear model of Kringlebotn (1988) was modified to represent the middle-ear disorders. Model predictions are compared with measurements. Results: For a given disorder, the general trends of the measurements and model were similar. The changes from normal in R, induced by the simulated disorder, generally depend on frequency and the extent of the disorder (except for the disarticulation). Systematic changes in middle-ear static pressure (up to ±300 daPa) resulted in systematic increases in R. These affects were most pronounced for frequencies up to 1000 to 2000 Hz. Above about 2000 Hz there were some asymmetries in behavior between negative and positive pressures. Results with fluid in the middle-ear air space were highly dependent on the percentage of the air space that was filled. Changes in R were minimal when a smaller fraction of the air space was filled with fluid, and as the air space was filled with more saline, R increased at most frequencies. Fixation of the stapes generally resulted in a relatively small low-frequency increase in R. Disarticulation of the incus with the stapes led to a consistent lowfrequency decrease in R with a distinctive minimum below 1000 Hz. Perforations of the tympanic membrane resulted in a decrease in R for frequencies up to about 2000 Hz; at these lower frequencies, smaller perforations led to larger changes from normal when compared with larger perforations. Conclusions: These preliminary measurements help assess the utility of power reflectance as a diagnostic tool for middle-ear disorders. In particular, the measurements document (1) the frequency ranges for which the changes are largest and (2) the extent of the changes from normal for a spectrum of middle-ear disorders

Probing Plasmodium falciparum sexual commitment at the single-cell level

Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign