Experimental violation of a cluster state Bell inequality

Cluster states are a new type of multiqubit entangled states with entanglement properties exceptionally well suited for quantum computation. In the present work, we experimentally demonstrate that correlations in a four-qubit linear cluster state cannot be described by local realism. This exploration is based on a recently derived Bell-type inequality [V. Scarani et al., Phys. Rev A 71, 042325 (2005)] which is tailored, by using a combination of three- and four-particle correlations, to be maximally violated by cluster states but not violated at all by GHZ states. We observe a cluster state Bell parameter of $2.59\pm 0.08$, which is more than 7 standard deviations larger than the threshold of 2 imposed by local realism.Comment: 4 pages, 2 figure

The Virtual Acoustic Spaces Unity Spatializer with custom head tracker

The virtual acoustic spaces (VAS) unity spatializer is a plugin for dynamic binaural synthesis for Unity. It can handle impulse responses (IRs) of arbitrary length (limited only by hardware resources). Hence, it is possible to calculate the binaural synthesis not only with head related transfer functions (HRTFs), but also on the basis of binaural room impulse responses (BRIRs). The plugin can also virtualize reflections calculated by raytracing and it is possible to load an individual IR set for each instance. In addition to being compatible with off-the-shelf cross reality (XR) hardware it features a Bluetooth binding for an easily built, custom-made head tracker based on an ESP32 board. It is therefore predestined for audio augmented reality applications

BOOST -- A Satellite Mission to Test Lorentz Invariance Using High-Performance Optical Frequency References

BOOST (BOOst Symmetry Test) is a proposed satellite mission to search for violations of Lorentz invariance by comparing two optical frequency references. One is based on a long-term stable optical resonator and the other on a hyperfine transition in molecular iodine. This mission will allow to determine several parameters of the standard model extension in the electron sector up to two orders of magnitude better than with the current best experiments. Here, we will give an overview of the mission, the science case and the payload.Comment: 11 pages, 2 figures, accepted for publication in Phys. Rev.

A reliability-aware chance-constrained battery sizing method for island microgrid

Island Microgrids can coordinate local energy resources, provide post-fault reliability improvements for local customers, and aggregate local power and energy resources to offer services to the wider system. A crucial component of an Island Microgrid is the battery energy storage system, which can manage local imbalances, alleviate constraints, and improve reliability by enabling post-fault islanding. A planning and sizing method is required to quantify and maximize the benefits of battery energy storage while avoiding over-investment and under-utilization. This paper combines comprehensive reliability assessment with chance-constrained convex optimization, via second-order cone programming, to optimally size energy storage within an Island Microgrid. Chance constraints are applied to the battery state-of-charge to avoid sizing the energy storage to accommodate extreme cases of uncertainty, avoiding uneconomic investment. The probability of reaching a state-of-charge constraint also indicates the likelihood that the battery energy storage system will be unable to facilitate island operation in the event of an outage, which affects the Island Microgrid reliability. The method is demonstrated on a real Austrian distribution network as part of the MERLON project. Results illustrate that an optimal trade-off can be identified between system reliability and operating cost when the probability of violating the chance constraints is 4.8%

Overview of central banks’ in-house credit assessment systems in the euro area

Los sistemas de evaluación del crédito desarrollados internamente por los bancos centrales nacionales (ICAS) son una fuente importante de valoración del riesgo de crédito dentro del marco de los activos de garantía de política monetaria del Eurosistema. En particular, los ICAS permiten que las entidades financieras aporten los préstamos concedidos a sociedades no financieras como garantía en las operaciones crediticias en las que se instrumenta la política monetaria del Eurosistema. En este sentido, los ICAS contribuyen a que los préstamos puedan ser utilizados como colateral, dado que generalmente no son aceptados como tal en la operativa privada de repos, y benefician potencialmente en mayor medida a los bancos de tamaño mediano o pequeño que financian a las pymes. Esto último conduce no solo a una ampliación del conjunto de activos de garantía disponibles en las entidades financieras y a una mejora del mecanismo de transmisión de la política monetaria, sino también a una menor dependencia de fuentes externas de valoración del riesgo de crédito, como las agencias externas de calificación. La importancia de los ICAS se ha puesto de manifiesto en las medidas aprobadas por el Eurosistema en abril de 2020 en respuesta a la crisis del COVID-19. Dichas medidas apoyaron un mayor uso de los préstamos como activos de garantía e, indirectamente, incrementaron la importancia de los ICAS como fuente de valoración del colateral. Este documento analiza en detalle el papel de los ICAS en el contexto de las operaciones crediticias de política monetaria del Eurosistema, describiendo las guías y los requerimientos más relevantes exigidos a los ICAS en términos, entre otros factores, de la estimación de las probabilidades de impago, el papel de los modelos estadísticos frente al análisis experto, la información utilizada en el proceso de evaluación y la validación periódica de su funcionamiento. Adicionalmente, describe los principales aspectos de cada uno de los ICAS actualmente aceptados como sistema de calificación por el Eurosistema, destacando tanto sus elementos comunes como los diferenciales.The in-house credit assessment systems (ICASs) developed by euro area national central banks (NCBs) are an important source of credit risk assessment within the Eurosystem collateral framework. They allow counterparties to mobilise as collateral the loans (credit claims) granted to non-financial corporations (NFCs). In this way, ICASs increase the usability of non-marketable credit claims that are normally not accepted as collateral in private market repo transactions, especially for small and medium-sized banks that lend primarily to small and medium-sized enterprises (SMEs). This ultimately leads not only to a widened collateral base and an improved transmission mechanism of monetary policy, but also to a lower reliance on external sources of credit risk assessment such as rating agencies. The importance of ICASs is exemplified by the collateral easing measures adopted in April 2020 in response to the coronavirus (COVID-19) crisis. The measures supported the greater use of credit claim collateral and, indirectly, increased the prevalence of ICASs as a source of collateral assessment. This paper analyses in detail the role of ICASs in the context of the Eurosystem’s credit operations, describing the relevant Eurosystem guidelines and requirements in terms of, among other factors, the estimation of default probabilities, the role of statistical models versus expert analysis, input data, validation analysis and performance monitoring. It then presents the main features of each of the ICASs currently accepted by the Eurosystem as credit assessment systems, highlighting similarities and differences

Financing essential HIV services: a new economic agenda.

Anna Vassall and colleagues discuss the need for, and challenges facing, innovative and sustainable financing of the HIV response. Please see later in the article for the Editors' Summary

Eplerenone prevents salt-induced vascular stiffness in Zucker diabetic fatty rats: a preliminary report

Background Aldosterone levels are elevated in a rat model of type 2 diabetes mellitus, the Zucker Diabetic fatty rat (ZDF). Moreover blood pressure in ZDF rats is salt-sensitive. The aim of this study was to examine the effect of the aldosterone antagonist eplerenone on structural and mechanical properties of resistance arteries of ZDF-rats on normal and high-salt diet. Methods After the development of diabetes, ZDF animals were fed either a normal salt diet (0.28%) or a high-salt diet (5.5%) starting at an age of 15 weeks. ZDF rats on high-salt diet were randomly assigned to eplerenone (100 mg/kg per day, in food) (ZDF+S+E), hydralazine (25 mg/kg per day) (ZDF+S+H), or no treatment (ZDF+S). Rats on normal salt-diet were assigned to eplerenone (ZDF+E) or no treatment (ZDF). Normoglycemic Zucker lean rats were also divided into two groups receiving normal (ZL) or high-salt diet (ZL+S) serving as controls. Systolic blood pressure was measured by tail cuff method. The experiment was terminated at an age of 25 weeks. Mesenteric resistance arteries were studied on a pressurized myograph. Specifically, vascular hypertrophy (media-to-lumen ratio) and vascular stiffness (strain and stress) were analyzed. After pressurized fixation histological analysis of collagen and elastin content was performed. Results Blood pressure was significantly higher in salt-loaded ZDF compared to ZDF. Eplerenone and hydralazine prevented this rise similarily, however, significance niveau was missed. Media-to-lumen ratio of mesenteric resistance arteries was significantly increased in ZDF+S when compared to ZDF and ZL. Both, eplerenone and hydralazine prevented salt-induced vascular hypertrophy. The strain curve of arteries of salt-loaded ZDF rats was significantly lower when compared to ZL and when compared to ZDF+S+E, but was not different compared to ZDF+S+H. Eplerenone, but not hydralazine shifted the strain-stress curve to the right indicating a vascular wall composition with less resistant components. This indicates increased vascular stiffness in salt-loaded ZDF rats, which could be prevented by eplerenone but not by hydralazine. Collagen content was increased in ZL and ZDF rats on high-salt diet. Eplerenone and hydralazine prevented the increase of collagen content. There was no difference in elastin content. Conclusion Eplerenone and hydralazine prevented increased media-to-lumen ratio in salt-loaded ZDF-rats, indicating a regression of vascular hypertrophy, which is likely mediated by the blood pressure lowering-effect. Eplerenone has additionally the potential to prevent increased vascular stiffness in salt-loaded ZDF-rats. This suggests an effect of the specific aldosterone antagonist on adverse vascular wall remodelling

Photonic entanglement as a resource in quantum computation and quantum communication

Entanglement is an essential resource in current experimental implementations for quantum information processing. We review a class of experiments exploiting photonic entanglement, ranging from one-way quantum computing over quantum communication complexity to long-distance quantum communication. We then propose a set of feasible experiments that will underline the advantages of photonic entanglement for quantum information processing.Comment: 33 pages, 4 figures, OSA styl

Cyclosporine A Impairs Norepinephrine-Induced Vascular Contractility

Usage of cyclosporine A (CsA) after kidney transplantation may be associated with development of nephrotoxicity and vasculopathy, but the mechanisms by which CsA causes vascular dysfunction are still under scrutiny. We established a transplantation model and investigated the effect of CsA on vascular contractility with the aid of a pressurized myograph in comparison with control and unilaterally nephrectomized rats. Results were correlated with mRNA expression studies of α- and β-adrenoreceptors, in mesenteric resistance arteries versus the thoracic aorta. Consequences of everolimus on functional properties as well as adrenoreceptor expression were also studied. CsA significantly downregulated expression of mesenteric adrenoreceptors, whereas no effect on aortic adrenoreceptors was seen. Administration of everolimus had no influence on mRNA adrenoreceptor expression in mesenteric resistance arteries. Furthermore, contractile responses of mesenteric resistance arteries to norepinephrine were markedly reduced after treatment with CsA, while there was no difference in contraction by endothelin. Everolimus did not alter the contractility response at all. In summary, norepinephrine-induced, but not endothelin-induced, contractile responses of mesenteric resistance arteries are blunted in CsA-treated rats. This finding was accompanied by a marked downregulation of adrenoreceptors in mesenteric resistance arteries and was limited to the usage of CsA

Effects of percutaneous coronary intervention on dyspnea in stable coronary artery disease

Background Dyspnea is a frequent symptom in patients with stable coronary artery disease (CAD) and is recognized as a possible angina equivalent. Objectives This study was to assess the impact of percutaneous coronary intervention (PCI) on dyspnea, quality of life, and angina pectoris in patients with stable CAD. Methods The prospective, multi-center PLA-pCi-EBO-pilot trial included 144 patients with symptomatic stable CAD and successful PCI. The prespecified endpoints angina pectoris (Seattle Angina Questionnaire–SAQ) and dyspnea (NYHA scale) were assessed 6 months after PCI. Predictors for symptomatic improvement were assessed with uni- and multivariable logistic regression analyses. Results Patients with concomitant dyspnea had worse SAQ physical limitation scores at baseline (49.5 ± 21.0 vs 58.9 ± 22.0, p = 0.013) but showed no difference for angina frequency or quality of life. Overall, symptomatic burden of angina pectoris and dyspnea was alleviated by PCI. However, patients with concomitant dyspnea had markedly worse scores for physical limitation (78.9 ± 25.0 vs 94.3 ± 10.6, p < 0.001), angina frequency (77.9 ± 22.8 vs 91.1 ± 12.4, p < 0.001), and quality of life (69.4 ± 24.1 vs 82.5 ± 14.4, p < 0.001) after PCI. The prevalence of dyspnea (NYHA class ≥ 2) declined from 73% before PCI to 54%. Of 95 initially dyspneic patients, 57 (60%) improved at least one NYHA class 6 months after PCI. In a multivariable logistic regression analysis, “atypical angina pectoris” was associated with improved NYHA class, whereas “diabetes mellitus” had a negative association. Conclusion PCI effectively reduced dyspnea, which is a frequent and demanding symptom in patients with CAD. The German Clinical Trials Register registration number is DRKS0001752 (www.drks.de)