Evolution of the Magnetic Excitations in Electron-Doped La_{2-x}Ce_{x}CuO_{4}.

We investigated the high energy spin excitations in electron-doped La_{2-x}Ce_{x}CuO_{4}, a cuprate superconductor, by resonant inelastic x-ray scattering (RIXS) measurements. Efforts were paid to disentangle the paramagnon signal from non-spin-flip spectral weight mixing in the RIXS spectrum at Q_{∥}=(0.6π,0) and (0.9π,0) along the (1 0) direction. Our results show that, for doping level x from 0.07 to 0.185, the variation of the paramagnon excitation energy is marginal. We discuss the implication of our results in connection with the evolution of the electron correlation strength in this system.

Linfoma vitreorretiniano: un reto diagnóstico / Vitreoretinal lymphoma: A diagnostic challenge

Se presenta el caso de un varón de 66años remitido por uveítis posterior con edema macular quístico recurrente en relación con posible enfermedad de Lyme previamente tratada. Debido a la recurrencia del edema macular pese al tratamiento corticoideo sistémico y local con dexametasona intravítrea, se instaura tratamiento biológico con adalimumab. Durante el seguimiento el paciente desarrolla lesiones subretinianas bilaterales compatibles con linfoma vitreorretiniano, por lo que se realiza vitrectomía, confirmando el diagnóstico de linfoma de célulaB grande.Se inicia tratamiento con quimioterapia sistémica con BRAM (carmustina, metotrexato, ara-C y rituximab), con buena respuesta. Dos años después, el paciente permanece sin recurrencias a nivel ocular ni sistémico.El linfoma vitreorretiniano es un tipo poco frecuente de linfoma primario del sistema nervioso central. El diagnóstico se ve frecuentemente retrasado debido a la inespecificidad de su sintomatología, que simula una uveítis posterior crónica; de ahí la importancia de la sospecha diagnóstica. (AU)

A 66-year-old man with posterior uveitis and recurrent cystic macular edema related to possible previously treated Lyme disease is presented. Due to the recurrence of macular edema despite systemic and local corticosteroid treatment with intravitreal dexamethasone, biological treatment with adalimumab was established. During follow-up, the patient developed bilateral subretinal lesions compatible with vitreoretinal lymphoma, so vitrectomy was performed, confirming the diagnosis of large B-cell lymphoma.Treatment with systemic chemotherapy with BRAM (carmustine, metotrexate, ara C, and rituximab) was started with a good answer. Two years later, the patient remains without ocular or systemic recurrences.Vitreoretinal lymphoma is a rare type of primary central nervous system lymphoma. The diagnosis is frequently delayed due to the nonspecific symptoms, which mimic chronic posterior uveitis, hence the importance with a diagnostic suspicion. (AU)

Vitreoretinal lymphoma: a diagnostic challenge.

A 66-year-old man with posterior uveitis and recurrent cystic macular edema related to possible previously treated Lyme disease is presented. Due to the recurrence of macular edema despite systemic and local corticosteroid treatment with intravitreal dexamethasone, biological treatment with Adalimumab was established. During follow-up, the patient developed bilateral subretinal lesions compatible with Vitreoretinal Lymphoma (VRL), so vitrectomy was performed, confirming the diagnosis of large B-cell lymphoma. Treatment with systemic chemotherapy with BRAM-Carmustine, Metrotexate, Ara C, and Rituximab was started with a good answer. Two years later, the patient remains without ocular or systemic recurrences. Vitreoretinal Lymphoma is a rare type of primary central nervous system lymphoma. The diagnosis is frequently delayed due to the nonspecific symptoms, which mimic chronic posterior uveitis, hence the importance with a diagnostic suspicion.

The retinal bacillary layer detachment: Clinical features and outcomes in posterior uveitis.

PURPOSE: To describe the clinical characteristics, presentation and response to treatment in posterior uveitis patients with bacillary layer detachment (BLD) seen on optical coherence tomography (OCT). MATERIALS AND METHODS: Retrospective review of patients with posterior uveitis and SD-OCT scans consistent with BLD. Data collected included demographics, uveitic etiology, treatment and duration of follow-up. Outcome measures included macular volume, central subfoveal thickness and visual acuity. RESULTS: Sixteen patients (20 eyes) were included. Twelve were female (75%). The mean age was 43.68 ± 14.7 years. The most frequent etiology of the uveitis was Vogt-Koyanagi-Harada (VKH) disease (n=10), followed by sympathetic ophthalmia (n=2). BLD was bilateral in four patients. Eight patients were treated with intravenous methylprednisolone boluses. Immunosuppressive therapies were required in 8 patients. The mean follow-up was 70 months (range: 2.0-216.0). CONCLUSION: BLD was observed in a series of posterior uveitis cases of various etiologies, showing functional and structural resolution with treatment in most cases.

Total synthesis of the natural (-)-205B alkaloid and its activity toward α7 nAChRs.

A new approach to the synthesis of the (-)-205B alkaloid is described in this paper. This work is characterised by the development of an efficient chirality transfer through a silyl tethered intramolecular alkylation reaction, an unprecedented tandem highly selective iridium catalyzed partial reduction of lactam coupled with an acid promoted aza-Prins reaction, and an almost complete stereochemical control in Shenvi's radical hydrogen atom transfer on an exocyclic methylene. The second part of this work demonstrates the positive allosteric behavior of this natural alkaloid toward α7 nAChRs, in contrast to the reported inhibitory effect of the unnatural enantiomer.

Gapped Collective Charge Excitations and Interlayer Hopping in Cuprate Superconductors.

We use resonant inelastic x-ray scattering to probe the propagation of plasmons in the electron-doped cuprate superconductor Sr_{0.9}La_{0.1}CuO_{2}. We detect a plasmon gap of ∼120 meV at the two-dimensional Brillouin zone center, indicating that low-energy plasmons in Sr_{0.9}La_{0.1}CuO_{2} are not strictly acoustic. The plasmon dispersion, including the gap, is accurately captured by layered t-J-V model calculations. A similar analysis performed on recent resonant inelastic x-ray scattering data from other cuprates suggests that the plasmon gap is generic and its size is related to the magnitude of the interlayer hopping t_{z}. Our work signifies the three dimensionality of the charge dynamics in layered cuprates and provides a new method to determine t_{z}.

Retrospective study of secondary implantation of retroiridial fixation lenses in patients without capsular support: functional results and complications.

INTRODUCTION: The correction of aphakia when there is no adequate capsular support remains a therapeutic challenge. The use of retroiridial fixation lenses has been extended given their lower complication rate compared to other available options. MATERIAL AND METHODS: Retrospective study including all cases operated with an Artisan® retropupillary aphakia implant. RESULTS: 33 eyes were included out of a total of 28 patients. The follow-up period has been 38.55 months (1-96). 32.3% had a lens dislocation and 67.7% had an intraocular lens dislocation. The previous mean best corrected visual acuity (BCVA) was 1.18 ± 0.79 logMAR and post-intervention 0.36 ± 0.62 (p < 0.01). 93.8% of the patients presented a final BCVA equal to or better and 62.5% an improvement of 3 or more lines. The most frequent complication was corectopia (31.3%) and hypotony in the immediate postoperative period (21.9%). An epiretinal membrane (ERM) developed in 18.8% and cystic macular oedema (CME) in 9.4%. The presence of complications in the postoperative period did not statistically influence the final BCVA. CONCLUSIONS: The retropupillary Artisan® lens allows the correction of aphakia with satisfactory visual results and a low rate of complications.

Estudio retrospectivo de implante secundario de lentes de fijación retroiridiana en pacientes sin soporte capsular: resultados funcionales y complicaciones / Retrospective study of secondary implantation of retroiridial fixation lenses in patients without capsular support: functional results and complications

Introducción La corrección de la afaquia en ausencia de un soporte capsular adecuado sigue suponiendo un reto terapéutico. Se ha extendido el uso de las lentes de fijación retroiridiana dada su menor tasa de complicaciones con respecto a otras opciones disponibles. Material y métodos Se realizó un estudio restrospectivo incluyendo todos los casos intervenidos con un implante Artisan® Afaquia retropupilar en un centro de tercer nivel. Resultados Se incluyeron 33 ojos de un total de 28 pacientes. El periodo de seguimiento ha sido de 38,55 meses (1-96). Un 32,3% tenían una luxación del cristalino y un 67,7% de la lente intraocular. La mejor agudeza visual corregida (MAVC) media previa fue 1,18 ± 0,79 logMAR y post intervención de 0,36 ± 0,62 (p < 0,01). El 93,8% de los pacientes presentó una MAVC final igual o mejor a la previa y el 62,5% una mejoría de 3 o más líneas. La complicación más frecuente fue la corectopia (31,3%) y la hipotonía transitoria en el postoperatorio inmediato (21,9%). En un 18,8% se desarrolló una membrana epirretiniana (MER) y en un 9,4% edema macular (EM). La presencia de complicaciones en el postoperatorio no influyó de forma estadísticamente significativa la MAVC final. Conclusiones La lente Artisan® retropupilar permite corregir la afaquia con resultados visuales satisfactorios y con una reducida tasa de complicaciones (AU)

Introduction The correction of aphakia when there is no adequate capsular support remains a therapeutic challenge. The use of retroiridial fixation lenses has been extended given their lower complication rate compared to other available options. Material and method Retrospective study including all cases operated with an Artisan® retropupillary aphakia implant. Results 33 eyes were included out of a total of 28 patients. The follow-up period has been 38.55 months (1-96). 32.3% had a lens dislocation and 67.7% had an intraocular lens dislocation. The previous mean best corrected visual acuity (BCVA) was 1.18 ± 0.79 logMAR and post-intervention 0.36 ± 0.62 (p < 0.01). 93.8% of the patients presented a final BCVA equal to or better and 62.5% an improvement of 3 or more lines. The most frequent complication was corectopia (31.3%) and hypotony in the immediate postoperative period (21.9%). An epiretinal membrane (ERM) developed in 18.8% and cystic macular oedema (CME) in 9.4%. The presence of complications in the postoperative period did not statistically influence the final BCVA. Conclusions The retropupillary Artisan® lens allows the correction of aphakia with satisfactory visual results and a low rate of complications (AU)

Susac syndrome: The importance of an early diagnosis.

A 38-year-old man who attended the emergency department with headache, accompanied by vomiting, bradypsychia and gait instability, for which he was admitted to Neurology for study. During his admission, he began to present bilateral hearing loss and blurred vision in the left eye, with areas of arterial occlusion and hyperfluorescence of the arterial wall being observed in the ophthalmological examination. As a result, he was diagnosed with Susac syndrome. He was treated with systemic corticosteroids, as well as with rituximab and subsequently, with intravenous immunoglobulins and mycophenolate mofetil. The patient managed to preserve visual acuity, with gait instability and bilateral hearing loss as sequelae. Early diagnosis of Susac syndrome is important, because a delay in the start of treatment can lead to irreversible sequelae such as deafness, blindness or neurological involvement.

Síndrome de Susac: la importancia de un diagnóstico precoz / Susac syndrome: The importance of an early diagnosis

Varón de 38 años que acude a urgencias con cefalea, acompañada de vómitos, bradipsiquia e inestabilidad de la marcha, por lo que ingresa en neurología para estudio. Durante el ingreso, comienza con hipoacusia bilateral y visión borrosa en el ojo izquierdo, apreciándose en la exploración oftalmológica áreas de oclusión arterial e hiperfluorescencia de la pared arterial, por lo que es diagnosticado de síndrome de Susac. Se realiza tratamiento con corticoides sistémicos, así como con rituximab, y posteriormente con inmunoglobulinas intravenosas y micofenolato de mofetilo. El paciente consigue preservar la agudeza visual y presenta como secuelas, inestabilidad de la marcha y pérdida de audición bilateral. El diagnóstico precoz del síndrome de Susac es importante, porque un retraso en el inicio del tratamiento puede dar lugar a secuelas irreversibles como sordera, ceguera o afectación neurológica (AU)

A 38-year-old man who attended the emergency department with headache, accompanied by vomiting, bradypsychia and gait instability, for which he was admitted to Neurology for study. During his admission, he began to present bilateral hearing loss and blurred vision in the left eye, with areas of arterial occlusion and hyperfluorescence of the arterial wall being observed in the ophthalmological examination. As a result, he was diagnosed with Susac syndrome. He was treated with systemic corticosteroids, as well as with rituximab and subsequently, with intravenous immunoglobulins and mycophenolate mofetil. The patient managed to preserve visual acuity, with gait instability and bilateral hearing loss as sequelae. Early diagnosis of Susac syndrome is important, because a delay in the start of treatment can lead to irreversible sequelae such as deafness, blindness or neurological involvement (AU)

Quadrupolar magnetic excitations in an isotropic spin-1 antiferromagnet.

The microscopic origins of emergent behaviours in condensed matter systems are encoded in their excitations. In ordinary magnetic materials, single spin-flips give rise to collective dipolar magnetic excitations called magnons. Likewise, multiple spin-flips can give rise to multipolar magnetic excitations in magnetic materials with spin S ≥ 1. Unfortunately, since most experimental probes are governed by dipolar selection rules, collective multipolar excitations have generally remained elusive. For instance, only dipolar magnetic excitations have been observed in isotropic S = 1 Haldane spin systems. Here, we unveil a hidden quadrupolar constituent of the spin dynamics in antiferromagnetic S = 1 Haldane chain material Y2BaNiO5 using Ni L3-edge resonant inelastic x-ray scattering. Our results demonstrate that pure quadrupolar magnetic excitations can be probed without direct interactions with dipolar excitations or anisotropic perturbations. Originating from on-site double spin-flip processes, the quadrupolar magnetic excitations in Y2BaNiO5 show a remarkable dual nature of collective dispersion. While one component propagates as non-interacting entities, the other behaves as a bound quadrupolar magnetic wave. This result highlights the rich and largely unexplored physics of higher-order magnetic excitations.

Magnetic excitations in infinite-layer nickelates.

The discovery of superconductivity in infinite-layer nickelates brings us tantalizingly close to a material class that mirrors the cuprate superconductors. We measured the magnetic excitations in these nickelates using resonant inelastic x-ray scattering at the Ni L 3-edge. Undoped NdNiO2 possesses a branch of dispersive excitations with a bandwidth of approximately 200 milli-electron volts, which is reminiscent of the spin wave of strongly coupled, antiferromagnetically aligned spins on a square lattice. The substantial damping of these modes indicates the importance of coupling to rare-earth itinerant electrons. Upon doping, the spectral weight and energy decrease slightly, whereas the modes become overdamped. Our results highlight the role of Mottness in infinite-layer nickelates.

Strong Superexchange in a d

The discovery of superconductivity in a d^{9-δ} nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni L-edge and O K-edge spectroscopy of the reduced d^{9-1/3} trilayer nickelates R_{4}Ni_{3}O_{8} (where R=La, Pr) and associated theoretical modeling. A magnon energy scale of ∼80 meV resulting from a nearest-neighbor magnetic exchange of J=69(4) meV is observed, proving that d^{9-δ} nickelates can host a large superexchange. This value, along with that of the Ni-O hybridization estimated from our O K-edge data, implies that trilayer nickelates represent an intermediate case between the infinite-layer nickelates and the cuprates. Layered nickelates thus provide a route to testing the relevance of superexchange to nickelate superconductivity.

The ligand-bound state of a G protein-coupled receptor stabilizes the interaction of functional cholesterol molecules.

Cholesterol is a major component of mammalian plasma membranes that not only affects the physical properties of the lipid bilayer but also is the function of many membrane proteins including G protein-coupled receptors. The oxytocin receptor (OXTR) is involved in parturition and lactation of mammals and in their emotional and social behaviors. Cholesterol acts on OXTR as an allosteric modulator inducing a high-affinity state for orthosteric ligands through a molecular mechanism that has yet to be determined. Using the ion channel-coupled receptor technology, we developed a functional assay of cholesterol modulation of G protein-coupled receptors that is independent of intracellular signaling pathways and operational in living cells. Using this assay, we discovered a stable binding of cholesterol molecules to the receptor when it adopts an orthosteric ligand-bound state. This stable interaction preserves the cholesterol-dependent activity of the receptor in cholesterol-depleted membranes. This mechanism was confirmed using time-resolved FRET experiments on WT OXTR expressed in CHO cells. Consequently, a positive cross-regulation sequentially occurs in OXTR between cholesterol and orthosteric ligands.

Resonant inelastic x-ray spectroscopy on UO2 as a test case for actinide materials.

Resonant inelastic x-ray spectroscopy at the uranium N4 absorption edge at 778 eV has been used to reveal the excitations in UO2 up to 1 eV. The earlier (1989) studies by neutron inelastic scattering of the crystal-field states within the 3H4 multiplet are confirmed. In addition, the first excited state of the 3F2 multiplet at ∼520 meV has been established, and there is a weak signal corresponding to the next excited state at ∼920 meV. This represents a successful application of soft x-ray spectroscopy to an actinide sample, and resolves an open question in UO2 that has been discussed for 50 years. The technique is described and important caveats are drawn about possible future applications.

Distinct classes of potassium channels fused to GPCRs as electrical signaling biosensors.

Ligand-gated ion channels (LGICs) are natural biosensors generating electrical signals in response to the binding of specific ligands. Creating de novo LGICs for biosensing applications is technically challenging. We have previously designed modified LGICs by linking G protein-coupled receptors (GPCRs) to the Kir6.2 channel. In this article, we extrapolate these design concepts to other channels with different structures and oligomeric states, namely a tetrameric viral Kcv channel and the dimeric mouse TREK-1 channel. After precise engineering of the linker regions, the two ion channels were successfully regulated by a GPCR fused to their N-terminal domain. Two-electrode voltage-clamp recordings showed that Kcv and mTREK-1 fusions were inhibited and activated by GPCR agonists, respectively, and antagonists abolished both effects. Thus, dissimilar ion channels can be allosterically regulated through their N-terminal domains, suggesting that this is a generalizable approach for ion channel engineering.

Publisher Correction: Electronic structure of the parent compound of superconducting infinite-layer nickelates.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Strongly Correlated Charge Density Wave in La_{2-x}Sr_{x}CuO_{4} Evidenced by Doping-Dependent Phonon Anomaly.

The discovery of charge-density-wave-related effects in the resonant inelastic x-ray scattering spectra of cuprates holds the tantalizing promise of clarifying the interactions that stabilize the electronic order. Here, we report a comprehensive resonant inelastic x-ray scattering study of La_{2-x}Sr_{x}CuO_{4} finding that charge-density wave effects persist up to a remarkably high doping level of x=0.21 before disappearing at x=0.25. The inelastic excitation spectra remain essentially unchanged with doping despite crossing a topological transition in the Fermi surface. This indicates that the spectra contain little or no direct coupling to electronic excitations near the Fermi surface, rather they are dominated by the resonant cross section for phonons and charge-density-wave-induced phonon softening. We interpret our results in terms of a charge-density wave that is generated by strong correlations and a phonon response that is driven by the charge-density-wave-induced modification of the lattice.

High-Temperature Charge-Stripe Correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}.

We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}. By differentiating elastic from inelastic scattering, it is demonstrated that charge-stripe correlations precede both the structural low-temperature tetragonal phase and the transport-defined pseudogap onset. The scattering peak amplitude from charge stripes decays approximately as T^{-2} towards our detection limit. The in-plane integrated intensity, however, remains roughly temperature independent. Therefore, although the incommensurability shows a remarkably large increase at high temperature, our results are interpreted via a single scattering constituent. In fact, direct comparison to other stripe-ordered compounds (La_{1.875}Ba_{0.125}CuO_{4}, La_{1.475}Nd_{0.4}Sr_{0.125}CuO_{4}, and La_{1.875}Sr_{0.125}CuO_{4}) suggests a roughly constant integrated scattering intensity across all these compounds. Our results therefore provide a unifying picture for the charge-stripe ordering in La-based cuprates. As charge correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4} extend beyond the low-temperature tetragonal and pseudogap phase, their emergence heralds a spontaneous symmetry breaking in this compound.