Theory of lossless polarization attraction in telecommunication fibers: erratum

An erroneous procedure of averaging the components of the Stokes vector of a polarization scrambled beam over the Poincare sphere introduced in our earlier paper [J. Opt. Soc. Am. B 28, 100-108 (2011)] has been corrected

The term structure of interest rates in a heterogeneous monetary union

Es difícil cuadrar la reacción asimétrica de las curvas de tipos en el área del euro tras el anuncio del programa de compras de emergencia frente a la pandemia (PEPP, por sus siglas en inglés) del Banco Central Europeo (BCE) con la interpretación ortodoxa de los efectos de las compras de bonos por parte de los bancos centrales, que enfatiza un mecanismo de «extracción de riesgo de duración». Motivados por esta observación, construimos un modelo de curvas de tipos soberanas en una unión monetaria de dos países, uno de los cuales emite bonos sin riesgo de impago, mientras que los bonos del otro pueden sufrir un impago. Obtenemos una solución analítica afín para la estructura temporal de los tipos soberanos, y descomponemos los rendimientos en componentes relacionados con la prima de plazo y con el riesgo de crédito. A continuación, extendemos el modelo básico para endogenizar la probabilidad de impago por parte del país periférico. Debido a la posibilidad de no poder refinanciar la deuda durante una crisis de liquidez, la probabilidad de impago soberano es una función creciente de la oferta de bonos soberanos neta de las tenencias del banco central. Calibramos el modelo para Alemania e Italia, y mostramos que el modelo replica bien la reacción de las curvas de tipos de estos países al anuncio del PEPP. Un mecanismo que llamamos «extracción de riesgo de impago» explica la mayor parte del impacto sobre los tipos italianos. La flexibilidad del diseño del PEPP aumentó de manera material el impacto de las compras.The highly asymmetric reaction of euro area yield curves to the announcement of the ECB’s pandemic emergency purchase programme (PEPP) is hard to reconcile with the standard “duration risk extraction” view of the transmission of central banks’ asset purchase policies. This observation motivates us to build a no-arbitrage model of the term structure of sovereign interest rates in a two-country monetary union, in which one country issues default-free bonds and the other issues defaultable bonds. We derive an affine term structure solution, and we decompose yields into term premium and credit risk components. In an extension, we endogenise the peripheral default probability, showing that the possibility of rollover crises makes it an increasing function of bond supply net of central bank holdings. We calibrate the model to Germany and Italy, showing that it matches well the reaction of these countries’ yield curves to the PEPP announcement. A channel we call “default risk extraction” accounts for most of the impact on Italian yields. The programme’s flexible design substantially enhanced this impact

Modular allylation of C(sp³)-H bonds by combining decatungstate photocatalysis and HWE olefination in flow

The late-stage introduction of allyl groups provides an opportunity to synthetic organic chemists for subsequent diversification, furnishing a rapid access to new chemical space. Here, we report the development of a modular synthetic sequence for the allylation of strong aliphatic C(sp(3))–H bonds. Our sequence features the merger of two distinct steps to accomplish this goal, including a photocatalytic Hydrogen Atom Transfer and an ensuing Horner–Wadsworth–Emmons (HWE) reaction. This practical protocol enables the modular and scalable allylation of valuable building blocks and has been applied to structurally complex molecules

Effectiveness of a home-environmental intervention package and an early child development intervention on child health and development in high-altitude rural communities in the Peruvian Andes: a cluster-randomised controlled trial

Unsafe drinking water, poor sanitation and hygiene, exposure to household air pollution and low cognitive and socio-emotional stimulation are risk factors affecting children in low- and middle-income countries. We implemented an integrated home-environmental intervention package (IHIP), comprising a kitchen sink, hygiene education and a certified improved biomass cookstove, and an early child development (ECD) programme to improve children´s health and developmental outcomes in the rural high-altitude Andes of Peru

Socio-cultural factors for breastfeeding cessation and their relationship with child diarrhoea in the rural high-altitude Peruvian Andes - a qualitative study

BACKGROUND: In some areas of the world, breast milk is seen as a potential source of child diarrhoea. While this belief has been explored in African and Southeast Asian countries, it remains vastly understudied in Latin American contexts. We investigate socio-cultural factors contributing to breastfeeding cessation in rural high-altitude populations of the Peruvian Andes. The role of socio- cultural factors in the local explanatory model of child diarrhoea, and whether these perceptions were integrated in the local healthcare system were assessed. METHODS: Within the framework of a randomised controlled trial, we conducted semi-structured interviews with 40 mothers and 15 health personnel from local healthcare centres involved in the trial. RESULTS: Cultural beliefs on breastfeeding cessation included the perception that breast milk turned into "blood" after six months and that breastfeeding caused child diarrhoea. We identified eight local types of child diarrhoea, and women linked six of them with breastfeeding practices. "Infection" was the only diarrhoea mothers linked to hygiene and the germ disease concept and perceived as treatable through drug therapy. Women believed that other types of diarrhoea could not be treated within the formal healthcare sector. Interviews with health personnel revealed no protocol for, or consensus about, the integration of the local explanatory model of child diarrhoea in local healthcare and service provision. CONCLUSIONS: The local explanatory model in rural Andean Peru connected breastfeeding with child diarrhoeas. Cultural beliefs regarding diarrhoea management may increase home treatments, even in cases of severe diarrhoeal episodes. Future national breastfeeding support programmes should promote peer-counselling approaches to reduce negative attitudes towards breastfeeding and health practitioners. Local explanatory models should be incorporated into provincial and regional strategies for child diarrhoea management to promote equity in health and improve provider-patient relationships

Reference standard for the uncertainty estimation of X–ray Computed Tomography measurements of complex macro-and micro-geometries

Traditionally, measuring both macro and micro geometries with a single device has been challenging in metrology. Coordinate Measuring Machines (CMM) are common devices for the inspection of large features, while optical microscopes can achieve resolutions in the order of micrometers in small areas. X-Ray Computed Tomography (XCT) has become a solution not only to characterize both micro and macro geometries, but also to inspect internal features without destroying the sample. In this field, various reference standards have been developed in order to verify the capabilities of XCT systems, these artefacts include geometrical features or profiles for roughness inspection. This paper shows the design and develompent of a reference standard for XCT test which includes internal and external geometrical features and profiles for macro and micro geometrical inspection. The model is manufactured by additive manufacturing (AM), easing the process of fabrication of the artefact and allowing to test the capabilities of this technology to produce reference standards

The Visibility Graph: a new method for estimating the Hurst exponent of fractional Brownian motion

Fractional Brownian motion (fBm) has been used as a theoretical framework to study real time series appearing in diverse scientific fields. Because its intrinsic non-stationarity and long range dependence, its characterization via the Hurst parameter H requires sophisticated techniques that often yield ambiguous results. In this work we show that fBm series map into a scale free visibility graph whose degree distribution is a function of H. Concretely, it is shown that the exponent of the power law degree distribution depends linearly on H. This also applies to fractional Gaussian noises (fGn) and generic f^(-b) noises. Taking advantage of these facts, we propose a brand new methodology to quantify long range dependence in these series. Its reliability is confirmed with extensive numerical simulations and analytical developments. Finally, we illustrate this method quantifying the persistent behavior of human gait dynamics.Comment: 5 pages, submitted for publicatio

Population of Merging Compact Binaries Inferred Using Gravitational Waves through GWTC-3

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMWe report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star-black hole mergers. We infer the binary neutron star merger rate to be between 10 and 1700 Gpc-3 yr-1 and the neutron star-black hole merger rate to be between 7.8 and 140 Gpc-3 yr-1, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and 44 Gpc-3 yr-1 at a fiducial redshift (z=0.2). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional to (1+z)κ with κ=2.9-1.8+1.7 for z≲1. Using both binary neutron star and neutron star-black hole binaries, we obtain a broad, relatively flat neutron star mass distribution extending from 1.2-0.2+0.1 to 2.0-0.3+0.3M⊙. We confidently determine that the merger rate as a function of mass sharply declines after the expected maximum neutron star mass, but cannot yet confirm or rule out the existence of a lower mass gap between neutron stars and black holes. We also find the binary black hole mass distribution has localized over- and underdensities relative to a power-law distribution, with peaks emerging at chirp masses of 8.3-0.5+0.3 and 27.9-1.8+1.9M⊙. While we continue to find that the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above approximately 60M⊙, which would indicate the presence of a upper mass gap. Observed black hole spins are small, with half of spin magnitudes below χi≈0.25. While the majority of spins are preferentially aligned with the orbital angular momentum, we infer evidence of antialigned spins among the binary population. We observe an increase in spin magnitude for systems with more unequal-mass ratio. We also observe evidence of misalignment of spins relative to the orbital angular momentu