How common is extra-articular knee deformity? How to achieve a ''safe zone'' alignment total knee arthroplasty in patients with extra-articular deformity.

The need for total knee arthroplasty is increasing considerably and one of the goals is to achieve post-surgical coronal alignment. Robotic surgical assistance achieves a functional alignment, which is a hip-knee-ankle angle of 0°. However, it is not possible to provide robotic assisted surgery to all our patients so we must include the full-length hip-to-ankle AP weight-bearing radiograph in preoperative planning to obtain a "safe zone" alignment, which is a post-surgical hip-knee-ankle Angle of 0 ± 3°. How can we achieve a "safe zone" alignment total knee arthroplasty in patients with extra-articular deformity?

La necesidad de artroplastia total de rodilla está aumentando considerablemente y uno de los objetivos es lograr la alineación coronal postquirúrgica. La asistencia quirúrgica robótica consigue una alineación funcional, que es un ángulo cadera-rodilla-tobillo de 0°. Sin embargo, no es posible ofrecer cirugía asistida por robot a todos nuestros pacientes, por lo que debemos incluir la radiografía AP de soporte de peso de cadera a tobillo de cuerpo entero en la planificación preoperatoria para obtener una alineación de "zona segura", que es un ángulo postquirúrgico cadera-rodilla-tobillo de 0 ± 3°. ¿Cómo podemos conseguir una artroplastia total de rodilla con alineación de "zona segura" en pacientes con deformidad extraarticular?

A high birefringence liquid crystal for lenses with large aperture.

This work presents the application of an experimental nematic liquid crystal (LC) mixture (1929) in a large aperture lens. The LC material is composed of terphenyl and biphenyl derivatives compounds with an isothiocyanate terminal group and fluorinated lateral substituents. The substitution with a strongly polar isothiocyanate group and an aromatic rigid core provides [Formula: see text]-electron coupling, providing high birefringence ([Formula: see text] at 636 nm and 23 °C) and low viscosity ([Formula: see text] = 17.03 mPa s). In addition, it also shows high values of birefringence at near infrared (0.318 at 1550 nm). The synthesis process is simple when comparing materials with high melting temperatures. The excellent properties of this LC mixture are demonstrated in a large aperture LC-tunable lens based on a transmission electrode structure. Thanks to the particular characteristics of this mixture, the optical power is high. The high birefringence makes this LC of specific interest for lenses and optical phase modulators and devices, both in the visible and infrared regions.

Aspherical liquid crystal lenses based on a variable transmission electrode.

In this work, a technique to generate aspherical liquid crystal lenses with positive and negative optical power is experimentally demonstrated. The main enabling element is a micro-metric electrode with variable spatial size. This produces a decreasing resistance towards the lens centre that generates the desired voltage/phase profiles. Then, the voltage is homogeneously distributed across the active area of the lens by micro-metric concentric electrodes. As it is demonstrated, the phase shift can be controlled with voltages from 0 to 4.5 VRMS. As a result, parabolic profiles are obtained both for negative and positive optical powers. Furthermore, this approach avoids some disadvantages of previous techniques; parabolic profiles can be obtained with only one lithographic step and one or two voltage sources. Other complex aspherical profiles could be fabricated using the same technique, such as elliptical or hyperbolic ones.

Analogue of electromagnetically induced transparency in square slotted silicon metasurfaces supporting bound states in the continuum.

In this work, a silicon metasurface designed to support electromagnetically induced transparency (EIT) based on quasi-bound states in the continuum (qBIC) is proposed and theoretically demonstrated in the near-infrared spectrum. The metasurface consists of a periodic array of square slot rings etched in a silicon layer. The interruption of the slot rings by a silicon bridge breaks the symmetry of the structure producing qBIC stemming from symmetry-protected states, as rigorously demonstrated by a group theory analysis. One of the qBIC is found to behave as a resonance-trapped mode in the perturbed metasurface, which obtains very high quality factor values at certain dimensions of the silicon bridge. Thanks to the interaction of the sharp qBIC resonances with a broadband bright background mode, sharp high-transmittance peaks are observed within a low-transmittance spectral window, thus producing a photonic analogue of EIT. Moreover, the resonator possesses a simple bulk geometry with channels that facilitate the use in biosensing. The sensitivity of the resonant qBIC on the refractive index of the surrounding material is calculated in the context of refractometric sensing. The sharp EIT-effect of the proposed metasurface, along with the associated strong energy confinement may find direct use in emerging applications based on strong light-matter interactions, such as non-linear devices, lasing, biological sensors, optical trapping, and optical communications.

Strongly resonant silicon slot metasurfaces with symmetry-protected bound states in the continuum.

In this work, a novel all-dielectric metasurface made of arrayed circular slots etched in a silicon layer is proposed and theoretically investigated. The structure is designed to support both Mie-type multipolar resonances and symmetry-protected bound states in the continuum (BIC). Specifically, the metasurface consists of interrupted circular slots, following the paradigm of complementary split-ring resonators. This configuration allows both silicon-on-glass and free-standing metasurfaces and the arc length of the split-rings provides an extra tuning parameter. The nature of both BIC and non-BIC resonances supported by the metasurface is investigated by employing the Cartesian multipole decomposition technique. Thanks to the non-radiating nature of the quasi-BIC resonance, extremely high Q-factor responses are calculated, both by fitting the simulated transmittance spectra to an extended Fano model and by an eigenfrequency analysis. Furthermore, the effect of optical losses in silicon on quenching the achievable Q-factor values is discussed. The metasurface features a simple bulk geometry and sub-wavelength dimensions. This novel device, its high Q-factors, and strong energy confinement open new avenues of research on light-matter interactions in view of new applications in non-linear devices, biological sensors, and optical communications.

Multifunctional light beam control device by stimuli-responsive liquid crystal micro-grating structures.

There is an increasing need to control light phase with tailored precision via simple means in both fundamental science and industry. One of the best candidates to achieve this goal are electro-optical materials. In this work, a novel technique to modulate the spatial phase profile of a propagating light beam by means of liquid crystals (LC), electro-optically addressed by indium-tin oxide (ITO) grating microstructures, is proposed and experimentally demonstrated. A planar LC cell is assembled between two perpendicularly placed ITO gratings based on microstructured electrodes. By properly selecting only four voltage sources, we modulate the LC-induced phase profile such that non-diffractive Bessel beams, laser stretching, beam steering, and 2D tunable diffraction gratings are generated. In such a way, the proposed LC-tunable component performs as an all-in-one device with unprecedented characteristics and multiple functionalities. The operation voltages are very low and the aperture is large. Moreover, the device operates with a very simple voltage control scheme and it is lightweight and compact. Apart from the demonstrated functionalities, the proposed technique could open further venues of research in optical phase spatial modulation formats based on electro-optical materials.

Positive-negative tunable liquid crystal lenses based on a microstructured transmission line.

In this work, a novel technique to create positive-negative tunable liquid crystal lenses is proposed and experimentally demonstrated. This structure is based on two main elements, a transmission line acting as a voltage divider and concentric electrodes that distribute the voltage homogeneously across the active area. This proposal avoids all disadvantages of previous techniques, involving much simpler fabrication process (a single lithographic step) and voltage control (one or two sources). In addition, low voltage signals are required. Lenses with switchable positive and negative focal lengths and a simple, low voltage control are demonstrated. Moreover, by using this technique other optical devices could be engineered, e.g. axicons, Powell lenses, cylindrical lenses, Fresnel lenses, beam steerers, optical vortex generators, etc. For this reason, the proposed technique could open new venues of research in optical phase modulation based on liquid crystal materials.

Evaluation of Plasma Disappearance Rate Indocyanine Green Clearance as a Predictor of Liver Graft Rejection in Donor Brain Death.

INTRODUCTION: There currently exist no quantitative methods to assess graft viability before the donor procurement procedure. In Europe, around 20% of liver grafts evaluated "in situ" by an experienced surgeon are discarded. The aim of this study is to evaluate the use of the plasma disappearance rate indocyanine green (PDR-ICG) clearance in predicting liver graft rejection to avoid this 20% of futile surgeries. OBJECTIVES: To evaluate PDR-ICG as a predictor of liver graft rejection in death brain donors compared with the gold standard evaluation by an experienced surgeon. MATERIAL AND METHODS: Prospective observational single center study. From March 2017 to July 2019, 29 donors were included in the study, 17 were men and 12 women with a median age of 68 years ± 16.9 years. Donors had an intensive care unit stay of 2 days ± 4 days. PDR-ICG was measured with PICCO2 monitor. Indocyanine green clearance dose was 0.25 mg/kg injected intravenously in the operating room just before donor procurement procedure is initiated. The surgeon was unaware of the PDR-ICG measure until the decision of graft acceptance was taken. Data regarding the donors and biopsy results were included in a prospective database. RESULTS: PDR-ICG measure could be obtained in 10 minutes in all of the cases included. The median PDR-ICG obtained was 18%/min (range, 2.4-31%/min). Graft rejection took place in 15 out of the 29 donors. PDR-ICG value was less than 10%/min in 6 of these rejected grafts and less than 15%/min in 10 donors. All donor grafts with PDR-ICG <15% were discarded. The graft had been discarded in 5 donors with a PDR-ICG >15%. CONCLUSIONS: In our study a plasma disappearance rate <10 would have identified the grafts that would be rejected, thus avoiding the displacement work and expense of the surgical team. These results should be confirmed in a multicentric study.

Ultrahigh-quality factor resonant dielectric metasurfaces based on hollow nanocuboids.

In this work, a dielectric metasurface consisting of hollow dielectric nanocuboids, with ultrahigh quality factor, is theoretically proposed and demonstrated. The variation of the hole size of the cuboid allows for the tuning of the resonant anapole mode in the nanoparticles. The metasurface is designed to operate in two complementary modes, namely electromagnetically induced transparency and narrowband selective reflection. Thanks to the non-radiative nature of the anapole resonances, the minimal absorption losses of the dielectric materials, and the near-field coupling among the metasurface nanoparticles, a very high quality factor of Q=2.5×106 is achieved. The resonators are characterized by a simple bulk geometry and the subwavelength dimensions of the metasurface permit operation in the non-diffractive regime. The high quality factors and strong energy confinement of the proposed devices open new avenues of research on light-matter interactions, which may find direct applications, e.g., in non-linear devices, biological sensors, laser cavities, and optical communications.

Donor Risk Index Has an Impact in Intraoperative Measure of Hepatic Artery Flow and in Clearance of Indocyanine Green: An Observational Cohort Study.

BACKGROUND: The increase in indications for liver transplantation has led to acceptance of donors with expanded criteria. The donor risk index (DRI) was validated with the aim of being a predictive model of graft survival based on donor characteristics. Intraoperative arterial hepatic flow and indocyanine green clearance (plasma clearance rate of indocyanine green [ICG-PDR]) are easily measurable variables in the intraoperative period that may be influenced by graft quality. Our aim was to analyze the influence of DRI on intraoperative liver hemodynamic alterations and on intraoperative dynamic liver function testing (ICG-PDR). METHODS: This investigation was an observational study of a single-center cohort (n = 228) with prospective data collection and retrospective data analysis. Measurement of intraoperative flow was made with a VeriQ flowmeter based on measurement of transit time (MFTT). The ICG-PDR was obtained from all patients with a LiMON monitor (Pulsion Medical Systems AG, Munich, Germany). DRI was calculated using a previously validated formula. Normally distributed variables were compared using Student's t test. Otherwise, the Mann-Whitney U test or Kruskal-Wallis test was applied, depending on whether there were 2 or more comparable groups. The qualitative variables and risk measurements were analyzed using the chi-square test. P < .05 was considered statistically significant. RESULTS: DRI score (mean ± SD) was 1.58 ± 0.31. The group with DRI >1.7 (poor quality) had an intraoperative arterial flow of 234.2 ± 121.35 mL/min compared with the group having DRI < 1.7 (high quality), with an intraoperative arterial flow of 287.24 ± 156.84 mL/min (P = .02). The group with DRI >1.70 had an ICG-PDR of 14.75 ± 6.52%/min at 60 minutes after reperfusion compared to the group with DRI <1.70, with an ICG-PDR of 16.68 ± 6.47%/min at 60 minutes after reperfusion (P = .09). CONCLUSION: Poor quality grafts have greater susceptibility to ischemia-reperfusion damage. Decreased intraoperative hepatic arterial flow may represent an increase in intrahepatic resistance early in the intraoperative period.

Are high-sensitivity troponins always reliable? Donor-recipient troponin transfusion in liver transplantation.

Blood troponins are used to diagnose perioperative myocardial injury and infarction. During liver transplantation, a passive donor-recipient troponin transfer with the graft may result in an increase of troponins in the transplant recipient questioning the diagnosis of myocardial injury. We present a case of liver transplantation with sudden elevation of recipient's serum troponin levels immediately after graft reperfusion and its subsequent normalization in which myocardial damage and other non-ischaemic potential causes were ruled out. Patient consent for publication was obtained prior to submission of the manuscript.

Quantifying pruning impacts on olive tree architecture and annual canopy growth by using UAV-based 3D modelling.

BACKGROUND: Tree pruning is a costly practice with important implications for crop harvest and nutrition, pest and disease control, soil protection and irrigation strategies. Investigations on tree pruning usually involve tedious on-ground measurements of the primary tree crown dimensions, which also might generate inconsistent results due to the irregular geometry of the trees. As an alternative to intensive field-work, this study shows a innovative procedure based on combining unmanned aerial vehicle (UAV) technology and advanced object-based image analysis (OBIA) methodology for multi-temporal three-dimensional (3D) monitoring of hundreds of olive trees that were pruned with three different strategies (traditional, adapted and mechanical pruning). The UAV images were collected before pruning, after pruning and a year after pruning, and the impacts of each pruning treatment on the projected canopy area, tree height and crown volume of every tree were quantified and analyzed over time. RESULTS: The full procedure described here automatically identified every olive tree on the orchard and computed their primary 3D dimensions on the three study dates with high accuracy in the most cases. Adapted pruning was generally the most aggressive treatment in terms of the area and volume (the trees decreased by 38.95 and 42.05% on average, respectively), followed by trees under traditional pruning (33.02 and 35.72% on average, respectively). Regarding the tree heights, mechanical pruning produced a greater decrease (12.15%), and these values were minimal for the other two treatments. The tree growth over one year was affected by the pruning severity and by the type of pruning treatment, i.e., the adapted-pruning trees experienced higher growth than the trees from the other two treatments when pruning intensity was low (<10%), similar to the traditionally pruned trees at moderate intensity (10-30%), and lower than the other trees when the pruning intensity was higher than 30% of the crown volume. CONCLUSIONS: Combining UAV-based images and an OBIA procedure allowed measuring tree dimensions and quantifying the impacts of three different pruning treatments on hundreds of trees with minimal field work. Tree foliage losses and annual canopy growth showed different trends as affected by the type and severity of the pruning treatments. Additionally, this technology offers valuable geo-spatial information for designing site-specific crop management strategies in the context of precision agriculture, with the consequent economic and environmental benefits.

Tunable liquid crystal cylindrical micro-optical array for aberration compensation.

A tunable aberration compensation device for rectangular micro-optical systems is proposed and demonstrated. This device, which is based in nematic liquid crystal and a micro-electrode structure, forms gradients in the index of refraction as a function of voltage. We have developed a fringe skeletonizing application in order to extract the 3D wavefront from an interference pattern. This software tool obtains the optical aberrations using Chebyshev polynomials. By using phase shifted electrical signals the aberrations can be controlled independently. A complete independent control over the spherical and coma aberration has been demonstrated. Also, an independent control over the astigmatism aberration has been demonstrated in a broad range. This device has promising applications where aberration compensation is required. The independent compensation achieved for some coefficients, such as astigmatism for example, is more than 2.4 waves.

Síndrome de distrés respiratorio agudo: revisión a propósito de la definición de Berlín / Acute respiratory distress syndrome: A review of the Berlin definition

El síndrome de distrés respiratorio agudo (SDRA) constituye una entidad de etiología muy diversa. La ausencia de definición universal se ha traducido en una serie de problemas a la hora de realizar un diagnóstico exhaustivo. Por ello, en los estudios publicados hasta el momento, la incidencia del SDRA y lesión pulmonar aguda (LPA) presentan cifras muy variables. La definición de la Conferencia Americana-Europea de Consenso se ha aplicado desde su publicación en 1994 después de 18 años, la Sociedad Europea de Medicina Intensiva convocó en 2011 a un equipo internacional de expertos en Berlín, para revisar la definición de SDRA. El objetivo de la definición de Berlín no es emplearla como pronóstico, sino mejorar la coherencia entre la investigación y la práctica clínica (AU)

Acute Respiratory Distress Syndrome (ARDS) is due to many causes. The absence of a universal definition up until now has led to a series of practical problems for a definitive diagnosis. The incidences of ARDS and Acute Lung Injury (ALI) vary widely in the current literature. The American-European Consensus Conference definition has been applied since its publication in 1994 and has helped to improve knowledge about ARDS. However, 18 years later, in 2011, the European Intensive Medicine Society, requested a team of international experts to meet in Berlin to review the ARDS definition. The purpose of the Berlin definition is not to use it as a prognostic tool, but to improve coherence between research and clinical practice

[Acute respiratory distress syndrome: a review of the Berlin definition]. / Síndrome de distrés respiratorio agudo: revisión a propósito de la definición de Berlín.

Acute Respiratory Distress Syndrome (ARDS) is due to many causes. The absence of a universal definition up until now has led to a series of practical problems for a definitive diagnosis. The incidences of ARDS and Acute Lung Injury (ALI) vary widely in the current literature. The American-European Consensus Conference definition has been applied since its publication in 1994 and has helped to improve knowledge about ARDS. However, 18 years later, in 2011, the European Intensive Medicine Society, requested a team of international experts to meet in Berlin to review the ARDS definition. The purpose of the Berlin definition is not to use it as a prognostic tool, but to improve coherence between research and clinical practice.