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We present a system able to discriminate pulses according to their duration with potential applications in all-optical signal multiplexing. The device is based on a directional coupler with nonlinear cores and metallic claddings with dimensions in a nanometric scale. Simulations are carried out using the FDTD technique for ultrashort pulses of femtosecond order. It is shown that the device is able to separate such pulses respect to a time-width threshold which depends on the total energy of the pulse.

En el debate en torno al papel de las lenguas extranjeras de finales del siglo xix en Estados Unidos, las dos estrategias más empleadas eran: la defensa del valor pragmático del idioma en relación con la política exterior norteamericana y la reivindicación de la tradición cultural asociada a la lengua meta. En los textos sobre el español se observa una tercera estrategia: la articulación de una hermandad continental, según la capacidad del lenguaje, para favorecer la comprensión simpatética entre los pueblos. Este trabajo analiza los matices con que los distintos sedimentos de la noción de simpatía influyen en tal criterio moral. The two most frequent strategies employed in the debate on the role of foreign languages in the United States at the end of the nineteenth century were: The defense of the pragmatic value of the languages for matters concerning US foreign policy, and the vindication of the cultural tradition linked to the language to be learnt. In the case of Spanish, a third strategy was also brought to bear: The articulation of a panamerican fraternity varying according to the capacity of each individual language to encourage a sympathetic understanding between peoples. This text analyzes the influence on this moral argument of the different nuances of the term sympathy.

We study switching operation in a plasmonic coupler using fs-pulses. Simulations using the finite difference time-domain method (FDTD) are carried out showing how the output changes as the pulse energy increases raising from zero to a maximum. Both cases of neglecting and realistic losses are considered in order to compare. The work is intended to explore the use of pulses for all-optical signal processing in a potentially interesting system for integrated photonics at the nanometric scale.

We present a method to study the dynamics of a quasi-two dimensional Bose-Einstein condensate which initially contains several vortices at arbitrary locations. The method allows one to find the analytical solution for the dynamics of the Bose-Einstein condensate in a homogeneous medium and in a parabolic trap, for the ideal non-interacting case. Secondly, the method allows one to obtain algebraic equations for the trajectories of the position of phase singularities present in the initial condensate along with time (the vortex lines). With these equations, one can predict quantities of interest, such as the time at which a vortex and an antivortex contained in the initial condensate will merge. For the homogeneous case, this method was introduced in the context of photonics. Here, we adapt it to the context of Bose-Einstein condensates, and we extend it to the trapped case for the first time. Also, we offer numerical simulations in the non-linear case, for repulsive and attractive interactions. We use a numerical split-step simulation of the non-linear Gross-Pitaevskii equation to determine how these trajectories and quantities of interest are changed by the interactions. We illustrate the method with several simple cases of interest, both in the homogeneous and parabolically trapped systems.

In this work, the unique optical properties of surface plasmon polaritons (SPPs), i.e. subwavelength confinement or strong electric field concentration, are exploited to demonstrate the propagation of light signal at 600 nm along distances in the range from 17 to 150 μm for Au nanostripes 500 nm down to 100 nm wide (30 nm of height), respectively, both theoretically and experimentally. A low power laser is coupled into an optical fiber tip that is used to locally excite the photoluminescence of colloidal quantum dots (QDs) dispersed in their surroundings. Emitted light from these QDs is generating the SPPs that propagate along the metal waveguides. Then, the above-referred propagation lengths were directly extracted from this novel experimental technique by studying the intensity of light decoupled at the output edge of the waveguide. Furthermore, an enhancement of the propagation length up to 0.4 mm is measured for the 500-nm-wide metal nanostripe, for which this effect is maximum. For this purpose, a simultaneous excitation of the same QDs dispersed in poly(methyl methacrylate) waveguides integrated with the metal nanostructures is performed by end-fire coupling an excitation laser energy as low as 1 KW/cm . The proposed mechanism to explain such enhancement is a non-linear interference effect between dielectric and plasmonic (super)modes propagating in the metal-dielectric structure, which can be apparently seen as an effective amplification or compensation effect of the gain material (QDs) over the SPPs, as previously reported in literature. The proposed system and the method to create propagating SPPs in metal waveguides can be of interest for the application field of sensors and optical communications at visible wavelengths, among other applications, using plasmonic interconnects to reduce the dimensions of photonic chips.

Background: The aim of this study was to compare the postoperative analgesic efficacy when a tibial nerve block was added to the femoral nerve block for total knee arthroplasty (TKA). Methods: A total of 60 patients were randomly assigned to the experimental group (EG) or the control group (CG) in a 1:1 ratio. The thirty patients who formed the CG underwent an ultrasound-guided femoral nerve block together with neuraxial anaesthesia and the administration of opioids and NSAIDs through an intravenous elastomeric pump for the management of the postoperative pain; the other thirty, who formed the EG, underwent neuraxial anaesthesia together with femoral and tibial nerve blocks. The efficacy of the analgesic effect was evaluated based on the numerical pain rating scale (NPRS) and on the need for analgesic rescue at different time intervals within 48 h after surgery. Results: At 24 h, the mean NPRS score in the EG and CG at rest was 1.50 ± 1.19 and 1.63 ± 1.60 [U = 443.5, p = 0.113], respectively. With joint movement, the mean NPRS score was 2.80 ± 1.49 and 3.57 ± 1.79 [U = 345, p = 0.113], respectively. Ten patients in the EG [33.3%] and 24 in the CG [80%] required rescue analgesia [Phi = 0.471, p < 0.001]. At 48 h, the mean NPRS score in the EG and CG at rest was 0.33 ± 0.60 and 0.43 ± 0.72 [U = 428, p = 0.681], respectively. With movement, the mean NPRS score was 1.03 ± 0.99 in the EG and 1.60 ± 1.07 in the CG [U = 315, p = 0.038]. No patient in the EG group required rescue analgesia, while three patients in the CG [10%] did [Phi = 0.229, p = 0.076]. The mean opioid dosage in the CG was 300 mg, whereas in the EG it was 40 mg ± 62.14 [U < 0.05, p < 0.001]. Conclusions: Adding a tibial nerve block to the femoral nerve block in TKA may achieve the same analgesic efficacy within 48 h after surgery and would reduce the systematic use of opioids.

We report a hollow-core negative-curvature fiber (HC-NCF) optical signal amplifier fabricated by the filling of the air microchannels of the fiber with all-inorganic CsPbBr3 perovskite nanocrystals (PNCs). The optimum fabrication conditions were found to enhance the optical gain, up to +3 dB in the best device. Experimental results were approximately reproduced by a gain assisted mechanism based on the nonlinear optical properties of the PNCs, indicating that signal regeneration can be achieved under low pump powers, much below the threshold of stimulated emission. The results can pave the road for new functionalities of the HC-NCF with PNCs, such as optical amplification, nonlinear frequency conversion and gas sensors.

In topological photonics, bulk‐edge correspondence is conventionally imported by direct analogy with electronic systems, overlooking the fundamentally distinct space‐time symmetries of Maxwell's and Schrödinger's equations. In this work, we challenge this prevailing paradigm by demonstrating that nontrivial bulk topology alone is insufficient to guarantee localized edge states in photonic platforms. Using a Su–Schrieffer–Heeger‐inspired photonic crystal, we unveil a generalized bulk‐edge correspondence intrinsically shaped by the relativistic nature of electromagnetic waves. This constraint imposes a strict frequency cutoff, a feature fundamentally absent in electronic topological insulators, which enables a new regime of frequency‐controlled spatial localization near the cutoff. Furthermore, we demonstrate that this generalized correspondence is polarization‐dependent: transverse electric and transverse magnetic edge modes exist in different parameter regimes and exhibit distinct dispersion relations, including different zero‐dispersion points. Our framework redefines the theoretical boundaries of topological photonics, unlocking new opportunities for polarization‐selective dispersion engineering and robust pulse propagation in topological photonic platforms. We show that unlike in electronic systems, localized edge states in topological photonics are governed not only by nontrivial bulk topology, but also by polarization‐dependent light‐line confinement conditions inherent to Maxwell's equations. This fundamentally generalized bulk‐edge correspondence unlocks new regimes of tunable near‐cutoff localization and unconventional edge state dispersion beyond the limits of conventional photonic platforms.

BackgroundRevision shoulder arthroplasty may involve the need to remove a well-fixed humeral stem. To avoid this, convertible platform systems have been introduced. The biomechanics of reverse total shoulder arthroplasty (rTSA) differs from anatomic shoulder arthroplasty (aTSA). The different humeral osteotomy and soft tissue tension may jeopardize the optimal results of the converted rTSA.The aim was to evaluate the radiographic parameters of soft tissue distraction when converting an aTSA to rTSA in a platform system and assess the capability of conversion without “over-stuffing” the shoulder in the “best-case scenario”.MethodsRadiographic analysis of soft tissue distraction parameters: difference in acromio-humeral distance, difference in lateral humeral offset and difference in latero-inferior displacement were evaluated in aTSA and in the converted rTSA in six different implants. Image analysing software was used on 10 non-deformed osteoarthritic shoulder X-rays to simulate conversion.ResultsThe greatest increase in arm length was found for Tornier Ascend Flex (26.8 ± 3.6 mm) while the smallest increase was observed with Lima SMR (19.3 ± 4 mm).The humerus remained most lateralized with the Zimmer Anatomical/Inverse ( − 1.4 ± 2.9 mm) while Lima SMR ( − 15.8 ± 2.7 mm) was more medialized. The greatest increase in latero-inferior distance was found in the onlay systems.A group analysis of onlay rTSA showed an increase of 46% in arm length (p < 0.0001), 83% larger humeral offset (p < 0.0001) and 144% increase in latero-inferior distraction (p < 0.0001) when compared to inlay rTSA.ConclusionThe conversion of aTSA to rTSA using a convertible platform system may lead to significant increase in radiographic parameters corresponding to soft tissue tension. This may alter the biomechanics, restrict the convertibility or jeopardize the optimal clinical outcome of rTSA even in the best-case scenario.

Electromagnetism plays an essential role, both in basic and applied physics research [...]