Towards quantum telescopes: demonstration of a two-photon interferometer for precision astrometry.

Classical optical interferometry requires maintaining live, phase-stable links between telescope stations. This requirement greatly adds to the cost of extending to long baseline separations and limits on baselines will in turn limit the achievable angular resolution. Here we describe a novel type of two-photon interferometer for astrometry, which uses photons from two separate sky sources and does not require an optical link between stations. Such techniques may make large increases in interferometric baselines practical, even by orders of magnitude, with a corresponding improvement in astrometric precision benefiting numerous fields in astrophysics. We tested a benchtop analogue version of the two-source interferometer and unambiguously observe correlated behavior in detections of photon pairs from two thermal light sources, in agreement with theoretical predictions. This work opens new possibilities in future astronomical measurements.

Distributed quantum sensing with mode-entangled spin-squeezed atomic states.

Quantum sensors are used for precision timekeeping, field sensing and quantum communication1-3. Comparisons among a distributed network of these sensors are capable of, for example, synchronizing clocks at different locations4-8. The performance of a sensor network is limited by technical challenges as well as the inherent noise associated with the quantum states used to realize the network9. For networks with only spatially localized entanglement at each node, the noise performance of the network improves at best with the square root of the number of nodes10. Here we demonstrate that spatially distributed entanglement between network nodes offers better scaling with network size. A shared quantum nondemolition measurement entangles a clock network with up to four nodes. This network provides up to 4.5 decibels better precision than one without spatially distributed entanglement, and 11.6 decibels improvement as compared to a network of sensors operating at the quantum projection noise limit. We demonstrate the generality of the approach with atomic clock and atomic interferometer protocols, in scientific and technologically relevant configurations optimized for intrinsically differential comparisons of sensor outputs.

Presurgical time and associated factors as predictors of acute perforated appendicitis: a prospective cohort study in a teaching pediatric hospital in Colombia.

BACKGROUND: We aim to determine the association between out and in-hospital factors with time, from the beginning of the symptoms to the surgery, in patients with acute appendicitis treated at Fundación Hospital Pediatrico La Misericordia (HOMI) in Colombia. METHODS: Eleven month prospective cohort study of pediatric patients at HOMI with acute appendicitis diagnosis taken to surgery. Data from the out-of-hospital phase was collected by surveying parents, and the data regarding the in-hospital phase was completed with medical records. We analyzed the association between the time from the beginning of the symptoms to the surgery, and out and in-hospital factors associated with this time using generalized linear models. RESULTS: Eight hundred three patients were included in the study. Total pre-surgical time was longer in perforated appendicitis (PA) group (2.65 days, standard deviation (SD) 1.88 vs. 2.04 days, SD 1.45) (p < 0.01). Factors associated with longer total and out-of-hospital presurgical times were age under 4 years old, lower socioeconomic status, father as a caregiver, self-medication, and underestimating disease severity. CONCLUSIONS: Out-of-hospital timing determines the longer pre-surgical time in complicated appendicitis. Younger age and lower socioeconomic status affect time significantly. We suggest the implementation of strategies in order to lower prehospital time, rates, and costs of complicated appendicitis.

Free Space Ramsey Spectroscopy in Rubidium with Noise below the Quantum Projection Limit.

We demonstrate the utility of optical cavity generated spin-squeezed states in free space atomic fountain clocks in ensembles of 390 000 ^{87}Rb atoms. Fluorescence imaging, correlated to an initial quantum nondemolition measurement, is used for population spectroscopy after the atoms are released from a confining lattice. For a free fall time of 4 milliseconds, we resolve a single-shot phase sensitivity of 814(61) microradians, which is 5.8(0.6) decibels (dB) below the quantum projection limit. We observe that this squeezing is preserved as the cloud expands to a roughly 200 µm radius and falls roughly 300 µm in free space. Ramsey spectroscopy with 240 000 atoms at a 3.6 ms Ramsey time results in a single-shot fractional frequency stability of 8.4(0.2)×10^{-12}, 3.8(0.2) dB below the quantum projection limit. The sensitivity and stability are limited by the technical noise in the fluorescence detection protocol and the microwave system, respectively.

Femtometer displacement resolution with phase-insensitive Doppler sensing.

The measurement of extremely small displacements is of utmost importance for fundamental studies and practical applications. One way to estimate a small displacement is to measure the Doppler shift generated in light reflected off a moving object, converting a displacement measurement into a frequency measurement. Here we show a sensitive device capable of measuring µHz/Hz Doppler frequency shifts corresponding to tens of femtometer displacements for a mirror oscillating at 2 Hz. While the Doppler shift measured is comparable to other techniques, the position sensitivity is orders of magnitude better, and operates over several orders of magnitude of Doppler frequency range. In addition, unlike other interferometric techniques, our device is phase insensitive, making it unusually robust to noise.

Anomalous vibration suppression in a weak-value-emulated heterodyne roll interferometer.

We experimentally validate the vibration suppression capabilities of a weak-value-like protocol. The phase-sensitive heterodyne technique exhibits advantageous characteristics of a weak measurement including anomalous amplification in sensitivity and technical noise suppression. It does not, however, leverage the entanglement between the system and meter to amplify the signal of interest, as is typical in a weak measurement. In this formalism, we demonstrate an amplification in sensitivity to the roll angle of over 700 times. High precision roll experiments anchor numerical simulations to show that the interferometer outperforms standard interferometry by a factor of 500 in terms of peak-to-peak noise amplitude. During the measurement of a rolling stage, technical noise - primarily in the form of vibrations - is substantially attenuated. This is the first demonstration of vibration suppression capabilities that are inherent to the light from a metrology instrument instead of achieved via mechanical damping. The emulation presented in this work also identifies an avenue to achieve anomalous amplification outside of the standard weak measurement protocol.

Ultrasensitive inverse weak-value tilt meter.

We present an interferometric technique for measuring ultrasmall tilts. The information of a tilt in one of the mirrors of a modified Sagnac interferometer is carried by the phase difference between the counter-propagating laser beams. Using a small misalignment of the interferometer, orthogonal to the plane of the tilt, a bimodal (or two-fringe) pattern is induced in the beam's transverse power distribution. By tracking the mean of such a distribution, using a split detector, a sensitive measurement of the phase is performed. With 1.2 mW of continuous-wave laser power, the technique has a shot noise limited sensitivity of 56 frad/Hz and a measured noise floor of 200 frad/Hz for tilt frequencies above 2 Hz. A tilt of 200 frad corresponds to a differential displacement of 4.0 fm in our setup. The novelty of the protocol relies on signal amplification due to the misalignment and on good performance at low frequencies. A noise floor of about 70 prad/Hz is observed between 2 and 100 mHz.

Continuous Matrix Product States for Quantum Fields: An Energy Minimization Algorithm.

The generalization of matrix product states (MPS) to continuous systems, as proposed in the breakthrough Letter of Verstraete and Cirac [Phys. Rev. Lett. 104, 190405 (2010).PRLTAO0031-900710.1103/PhysRevLett.104.190405], provides a powerful variational ansatz for the ground state of strongly interacting quantum field theories in one spatial dimension. A continuous MPS (cMPS) approximation to the ground state can be obtained by simulating a Euclidean time evolution. In this Letter we propose a cMPS optimization algorithm based instead on energy minimization by gradient methods and demonstrate its performance by applying it to the Lieb-Liniger model (an integrable model of an interacting bosonic field) directly in the thermodynamic limit. We observe a very significant computational speed-up, of more than 2 orders of magnitude, with respect to simulating a Euclidean time evolution. As a result, a much larger cMPS bond dimension D can be reached (e.g., D=256 with moderate computational resources), thus helping unlock the full potential of the cMPS representation for ground state studies.

Medication adherence and persistence over time with self-administered TNF-alpha inhibitors among young adult, middle-aged, and older patients with rheumatologic conditions.

OBJECTIVE: Self-injectable TNF inhibitors are increasingly used early in the chronic treatment of moderate to severe rheumatologic conditions. We estimated medication adherence/persistence over time following initiation in young adult and older adult patients with rheumatoid arthritis, ankylosing spondylitis or psoriatic arthritis. METHODS: We conducted a retrospective cohort study of patients aged 18+ years newly initiating etanercept, adalimumab, certolizumab pegol, or golimumab using the Truven Health MarketScan Database between 2009 and 2013. Pharmacy dispensing data were used to calculate 12-month medication possession ratios (MPR) and determine adherence (MPR ≥ 0.80) for up to 3 years after starting therapy. Persistence over each 12-month interval was defined as not having a ≥92-day treatment gap. Multivariable generalized estimating equation models were used to calculate odds ratios (OR) and robust 95% confidence intervals (CI) for associations between patient characteristics and repeated adherence/persistence measures over time. RESULTS: Among 53,477 new users, 14% were young adults (18-34 years), 49% middle-aged (35-54 years), and 37% older adults (55+ years). Overall, 37% of patients were adherent and 83% were persistent in the first year of therapy. The lowest adherence (17%) and persistence (70%) were observed among young adult patients by Year +3. Compared to older adults, middle-aged (OR = 0.73, 95% CI: 0.71-0.76) and young adults (OR = 0.50, 95% CI: 0.47-0.53) were less likely to be adherent. Higher Charlson comorbidity scores, hospitalizations, and emergency department visits were associated with non-adherence/non-persistence. CONCLUSIONS: We observed low adherence to self-administered TNF inhibitors but most patients remained persistent over time. Further efforts to improve adherence in young adults and patients with greater comorbidity are needed.

Anomalous amplification of a homodyne signal via almost-balanced weak values.

We propose precision measurements of ultra-small angular velocities of a mirror within a modified Sagnac interferometer, where the counter-propagating beams are spatially separated, using the recently proposed technique of almost-balanced weak values amplification (ABWV) [Phys. Rev. Lett.116, 100803 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.100803]. The separation between the two beams provides additional amplification with respect to using collinear beams in a Sagnac interferometer. Within the same setup, the weak-value amplification technique is also performed for comparison. Much higher amplification factors can be obtained using the almost-balanced weak values technique, with the best one achieved in our experiments being as high as 1.2×107. In addition, the amplification factor monotonically increases with decreasing of the post-selection phase for the ABWV case in our experiments, which is not the case for weak-value amplification (WVA) at small post-selection phases. Both techniques consist of measuring the angular velocity. The sensitivity of the ABWV technique is ∼38 nrad/s per averaged pulse for a repetition rate of 1 Hz and ∼33 nrad/s per averaged pulse for the WVA technique.

Can Anomalous Amplification be Attained without Postselection?

We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique.

Spin Andreev-like reflection in metal-Mott insulator heterostructures.

Using the time-dependent density-matrix renormalization group (tDMRG), we study the time evolution of electron wave packets in one-dimensional (1D) metal-superconductor heterostructures. The results show Andreev reflection at the interface, as expected. By combining these results with the well-known single-spin-species electron-hole transformation in the Hubbard model, we predict an analogous spin Andreev reflection in metal-Mott insulator heterostructures. This effect is numerically confirmed using 1D tDMRG, but it is expected to also be present in higher dimensions, as well as in more general Hamiltonians. We present an intuitive picture of the spin reflection, analogous to that of Andreev reflection at metal-superconductor interfaces. This allows us to discuss a novel antiferromagnetic proximity effect. Possible experimental realizations are discussed.

Evolución de la tensión arterial durante la gestación, en gestantes sanas inscritas en el programa de control prenatal de una entidad del primer nivel de atención en Manizales, Colombia, 2010: 2013 / The evolution of the blood pressure in relation to the gestational age and the body mass index in pregnant women enrolled in the program of prenatal control in an entity of the first level of attention in Manizales, Colombia, 2010: 2013

Describir los cambios de la tensión arterial de mujeres embarazadas con relación a la edad gestacional y al índice de masa corporal, en una muestra de gestantes controladas en ASSBASALUD ESE (Manizales, Caldas, Colombia) entre los años 2010-2013. Materiales y métodos: Se consultaron historias clínicas de 1923 gestantes sanas. Se efectuaron análisis, por semana, mes y trimestre. Resultados: La relación de presión arterial promedio con cada mes mostró un descenso en las tres presiones, aunque más marcado en la presión arterial diastólica y media, hasta el quinto mes de gestación hasta 103 para PAS, 65 para PAD, y 77 mmHg para PAM en promedio, para iniciar su ascenso hasta el final de la gestación obteniendo las cifras más elevadas en el decimo mes con valores de 106, 67,5 y 80,12 mmHg respectivamente en promedio. Trimestralmente no se encontró una diferencia significativa entre el primero y el segundo trimestre para PAS, pero sí para PAD y PAM, y para los tres casos un aumento marcado en el último trimestre. Por semana se efectuaron estimaciones curvilíneas cuadráticas y cúbicas para las tres presiones, resultando todas significativas con p=0,000, tanto para las regresiones globales, como para el término independiente y los coeficientes. Conclusión: Se encuentra que la presión arterial tiene el mismo comportamiento de la población global, ambas presiones tienen un comportamiento en curva Sigma, pero lo hacen con un promedio inferior a los estudios realizados en Europa, no así en América-Latina donde las cifras también son bajas...

Competition between covalent bonding and charge transfer at complex-oxide interfaces.

Here we study the electronic properties of cuprate-manganite interfaces. By means of atomic resolution electron microscopy and spectroscopy, we produce a subnanometer scale map of the transition metal oxidation state profile across the interface between the high Tc superconductor YBa2Cu3O7-δ and the colossal magnetoresistance compound (La,Ca)MnO3. A net transfer of electrons from manganite to cuprate with a peculiar nonmonotonic charge profile is observed. Model calculations rationalize the profile in terms of the competition between standard charge transfer tendencies (due to band mismatch), strong chemical bonding effects across the interface, and Cu substitution into the Mn lattice, with different characteristic length scales.

Trampas extracelulares de ADN de eosinófilos en alergias / Eosinophil extracellular DNA traps in allergies

La alergia es una reacción de hipersensibilidad iniciada por mecanismos inmunológicos y mediada por anticuerpos o células; se desencadena en individuos previamente sensibilizados a un alérgeno. En la mayoría de los casos, el anticuerpo responsable de la reacción alérgica es la inmunoglobulina E (IgE). Según la naturaleza y el mecanismo de entrada del alérgeno se producirá la IgE específica; en las alergias se afectan determinados órganos y tejidos con producción de sintomatologías específicas. Uno de los mecanismos que los eosinófilos utilizan durante la fase de respuesta de las alergias son sus trampas extracelulares (EET), que han sido poco estudiadas en cuanto a su inducción, regulación y función. Hasta el momento se conoce la presencia de dichas trampas en procesos inflamatorios intestinales, enfermedades autoinmunes y múltiples procesos infecciosos, pero se han hecho pocas investigaciones sobre su implicación en las enfermedades alérgicas. Este es un artículo de revisión sobre la estructura de las EET, las moléculas involucradas en su formación y la posible función que desempeñan en la patogénesis de las alergias. Además, se revisan los principales aspectos de los procesos celulares y moleculares involucrados en la inmunopatogénesis de las alergias y los aspectos centrales de la estructura, composición y funcionamiento de los eosinófilos.

Allergy is a hypersensitivity reaction initiated by specific immunologic mechanisms. It can be mediated by antibodies or cells, developed in individuals previously sensitized by an allergen. In most cases, the antibody responsible for the allergic reaction is immunoglobulin E (IgE). Depending on the nature and mechanism of entry of the allergen, it will bring about the production of specific IgE affecting certain organs and tissues with specific symptoms. Eosinophil extracellular DNA traps or EETs are one of the mechanisms used by eosinophils been well studied in terms of their induction, regulation and function. EETs have been detected in inflammatory intestinal processes, autoimmune diseases and multiple infectious diseases, but few investigations have been made about their involvement in allergic diseases. This is a review about the structure of EETs, the molecules involved in their formation, and their possible role in the pathogenesis of allergies. Furthermore, the main aspects of cellular and molecular processes involved in the immunopathogenesis of allergies, and the central aspects of the structure, composition and functioning of eosinophils are reviewed.

Exotic magnetic order in the orbital-selective Mott regime of multiorbital systems.

The orbital-selective Mott phase of multiorbital Hubbard models has been extensively analyzed before using static and dynamical mean-field approximations. In parallel, the properties of block states (antiferromagnetically coupled ferromagnetic spin clusters) in Fe-based superconductors have also been much discussed. The present effort uses numerically exact techniques in one-dimensional systems to report the observation of block states within the orbital-selective Mott phase regime, connecting two seemingly independent areas of research, and providing analogies with the physics of double-exchange models.

Weak-values technique for velocity measurements.

In a recent Letter, Brunner and Simon proposed an interferometric scheme using imaginary weak values with a frequency-domain analysis to outperform standard interferometry in longitudinal phase shifts [Phys. Rev. Lett105, 010405 (2010)]. Here we demonstrate an interferometric scheme combined with a time-domain analysis to measure longitudinal velocities. The technique employs the near-destructive interference of non-Fourier limited pulses, one Doppler shifted due to a moving mirror in a Michelson interferometer. We achieve a velocity measurement of 400 fm/s and show our estimator to be efficient by reaching its Cramér-Rao bound.

Sistema NADPH oxidasa: nuevos retos y perspectivas / NADPH oxidase system: new challenges and perspectives

El sistema NADPH oxidasa es un complejo multiproteico encargado de producir especies reactivas del oxígeno (ROS, por reactive oxygen species) en diferentes células y tejidos. Es de gran importancia en las células fagocíticas (principalmente neutrófilos y macrófagos) porque participa en la destrucción de microorganismos patógenos, mediante la fagocitosis y la formación de las trampas extracelulares de neutrófilos (NET, por neutrophils extracelular traps), así como en la activación de procesos inflamatorios. Las alteraciones en la producción de ROS por parte de las células fagocíticas a causa de defectos genéticos en los componentes del sistema generan la inmunodeficiencia primaria denominada enfermedad granulomatosa crónica (EGC). Este es un artículo de revisión sobre los componentes del sistema NADPH oxidasa, su distribución celular, mecanismo de activación y acción, así como de las funciones que desempeña en otros tejidos. Además, se revisan los defectos moleculares que llevan a la EGC y el tratamiento de esta, incluyendo la terapia con IFNγ, y finalmente las perspectivas para el estudio del sistema.

The NADPH oxidase system is a multiprotein complex that acts as the main source of reactive oxygen species (ROS) in different cells and tissues. In phagocytic cells (mainly macrophages and neutrophils) it is essential for eliminating pathogenic microorganisms, by phagocytosis and the formation of neutrophil extracellular traps (NETs). It also contributes to inflammatory processes. Genetic defects in the components of the system cause alterations in the production of ROS by phagocytic cells, leading to the primary immunodeficiency known as chronic granulomatous disease (CGD). This is a review article on the components of the NADPH oxidase system, its cellular distribution, activation, mechanisms of action, and roles in other tissues. The different molecular defects that lead to EGC are also reviewed, as well as its treatment, including therapy with IFNγ, and the prospects for the study of the system.

Quantum interference in coherent molecular conductance.

Coherent electronic transport through individual molecules is crucially sensitive to quantum interference. We investigate the zero-bias and zero-temperature conductance through pi-conjugated annulene molecules weakly coupled to two leads for different source-drain configurations, finding an important reduction for certain transmission channels and for particular geometries as a consequence of destructive quantum interference between states with definite momenta. When translational symmetry is broken by an external perturbation we find an abrupt increase of the conductance through those channels. Previous studies concentrated on the effect at the Fermi energy, where this effect is very small. By analyzing the effect of symmetry breaking on the main transmission channels we find a much larger response thus leading to the possibility of a larger switching of the conductance through single molecules.