Outcomes of Cystoid Macular Edema Following Descemet's Membrane Endothelial Keratoplasty in a Referral Center for Keratoplasty in Spain: Retrospective Study

The aim of this study was to analyze the outcomes of eyes with visually significant cystoid macular œdema (vs-CMO) after Descemet membrane endothelial keratoplasty (DMEK) in a referral center for keratoplasty in Spain. We conducted a retrospective, single-surgeon case series of eyes that developed post-DMEK vs-CMO performed between January 2011 and December 2020. Data collected included: indication for DMEK; biometric data; ocular comorbidities; past medical history; time to detection of vs-CMO after DMEK (T, weeks); best-corrected visual acuity (BCVA, logMAR) and central retinal thickness (CRT, µm) at diagnosis of vs-CMO, after resolution of CMO, and at last follow-up; and management strategy. Main outcomes analyzed were incidence of vs-CMO, improvement in BCVA and CRT after treatment of vs-CMO. Of 291 consecutive DMEK surgeries, 14 eyes of 13 patients (4.8%) developed vs-CMO. Five patients (38.5%) had history of CMO, and 28.6% of eyes had ophthalmic comorbidities. Median (P25-P75) T was 4 (3-10) weeks. Treatment success was observed in 12/13 eyes (92.3%), two of which required second-line treatment. In successful cases (median time-to-resolution 3.0 (2.0-3.5) months), median BCVA improved from 0.60 (0.40-0.80) logMAR to 0.30 (0.15-0.40) logMAR (p = 0.002) after treatment, and median CRT improved from 582.5 (400.0-655.0) µm to 278.0 (258.0-294.0) µm (p = 0.005). In our study, we found a 4.8% rate of post-DMEK vs-CMO, with most cases occurring in the first 3 months after surgery. Good functional and anatomical outcomes are expected in most eyes, without treatment-related complications or implications in graft outcomes. Additional studies are encouraged to determine a standardized protocol for post-DMEK vs-CMO.info:eu-repo/semantics/publishedVersio

THETA-rhythm makes the world go round:dissociative effects of TMS theta versus alpha entrainment of right pTPJ on embodied perspective transformations

Being able to imagine another person's experience and perspective of the world is a crucial human ability and recent reports suggest that humans "embody" another's viewpoint by mentally rotating their own body representation into the other's orientation. Our recent Magnetoencephalography (MEG) data further confirmed this notion of embodied perspective transformations and pinpointed the right posterior temporo-parietal junction (pTPJ) as the crucial hub in a distributed network oscillating at theta frequency (3-7 Hz). In a subsequent transcranial magnetic stimulation (TMS) experiment we interfered with right pTPJ processing and observed a modulation of the embodied aspects of perspective transformations. While these results corroborated the role of right pTPJ, the notion of theta oscillations being the crucial neural code remained a correlational observation based on our MEG data. In the current study we therefore set out to confirm the importance of theta oscillations directly by means of TMS entrainment. We compared entrainment of right pTPJ at 6 Hz vs. 10 Hz and confirmed that only 6 Hz entrainment facilitated embodied perspective transformations (at 160° angular disparity) while 10 Hz slowed it down. The reverse was true at low angular disparity (60° between egocentric and target perspective) where a perspective transformation was not strictly necessary. Our results further corroborate right pTPJ involvement in embodied perspective transformations and highlight theta oscillations as a crucial neural code

Density Changes in Low Pressure Gas Targets for Electron Scattering Experiments

A system of modular sealed gas target cells has been developed for use in electron scattering experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). This system was initially developed to complete the MARATHON experiment which required, among other species, tritium as a target material. Thus far, the cells have been loaded with the gas species 3H, 3He, 2H, 1H and 40Ar and operated in nominal beam currents of up to 22.5 uA in Jefferson Lab's Hall A. While the gas density of the cells at the time of loading is known, the density of each gas varies uniquely when heated by the electron beam. To extract experimental cross sections using these cells, density dependence on beam current of each target fluid must be determined. In this study, data from measurements with several beam currents within the range of 2.5 to 22.5 uA on each target fluid are presented. Additionally, expressions for the beam current dependent fluid density of each target are developed.Comment: 8 pages, 12 figures, 4 table

Entre negro oscuro y moreno claro: discursos e identidades étnicas en niños y niñas afrodescendientes en contexto escolar en Bogotá

A partir del análisis del discurso y la psicología social, este texto intenta comprender la manera como construyen las identidades étnicas niños y niñas afrodescendientes entre seis y doce años en contextos escolares en Bogotá. El objetivo es identificar los mecanismos discursivos que permiten conocer cómo se originan los procesos identitarios a partir de aceptación o negación de lo étnico, y que pueden llevar o incidir en procesos de adaptación, resistencia o negociación. Los hallazgos sugieren que los niños inician temprano su autoidentificación étnica a partir del color de la piel, en el que diferencian una amplia escala cromática, tendiente al blanquemiento. Tienen distinto grado de valoración étnica que va del orgullo al rechazo. En las relaciones interétnicas tienden a negar el conflicto o a minimizarlo y existe una tendencia a negarse a hablar de él. Identifican la causa del problema como un asunto de cantidad, en el que ellos son minoría en Bogotá. En las dinámicas interétnicas algunos aceptan los estereotipos que se les asignan; otros lo rechazan y otros se burlan de ellos

Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering

We propose to conduct a measurement of the Virtual Compton Scattering reaction in Hall C that will allow the precise extraction of the two scalar Generalized Polarizabilities (GPs) of the proton in the region of $Q^2=0.05~(GeV/c)^2$ to $Q^2=0.50~(GeV/c)^2$. The Generalized Polarizabilities are fundamental properties of the proton, that characterize the system's response to an external electromagnetic (EM) field. They describe how easily the charge and magnetization distributions inside the system are distorted by the EM field, mapping out the resulting deformation of the densities in the proton. As such, they reveal unique information regarding the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents together. Recent measurements of the proton GPs have challenged the theoretical predictions, particularly in regard to the electric polarizability. The magnetic GP, on the other hand, can provide valuable insight to the competing paramagnetic and diamagnetic contributions in the proton, but it is poorly known within the region where the interplay of these processes is very dynamic and rapidly changing.The unique capabilities of Hall C, namely the high resolution of the spectrometers combined with the ability to place the spectrometers in small angles, will allow to pin down the dynamic signature of the GPs through high precision measurements combined with a fine mapping as a function of $Q^2$. The experimental setup utilizes standard Hall C equipment, as was previously employed in the VCS-I (E12-15-001) experiment, namely the HMS and SHMS spectrometers and a 10 cm liquid hydrogen target. A total of 59 days of unpolarized 75 $\mu A$ electron beam with energy of 1100 MeV (6 days) and 2200 MeV (53 days) is requested for this experiment

Search for axion-like particles through nuclear Primakoff production using the GlueX detector

We report on the results of the first search for the production of axion-like particles (ALP) via Primakoff production on nuclear targets using the GlueX detector. This search uses an integrated luminosity of 100 pb$^{-1}\cdot$nucleon on a $^{12}$C target, and explores the mass region of 200 < $m_a$ < 450 MeV via the decay $X\rightarrow\gamma\gamma$. This mass range is between the $\pi^0$ and $\eta$ masses, which enables the use of the measured $\eta$ production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the coupling on the scale of $O$(1 TeV). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background in GlueX, which we treat by using data on $^4$He to estimate and subtract these backgrounds. We comment on how this search can be improved in a future higher-statistics dedicated measurement

A Direct Measurement of Hard Two-Photon Exchange with Electrons and Positrons at CLAS12

One of the most surprising discoveries made at Jefferson Lab has been the discrepancy in the determinations of the proton's form factor ratio $\mu_p G_E^p/G_M^p$ between unpolarized cross section measurements and the polarization transfer technique. Over two decades later, the discrepancy not only persists but has been confirmed at higher momentum transfers now accessible in the 12-GeV era. The leading hypothesis for the cause of this discrepancy, a non-negligible contribution from hard two-photon exchange, has neither been conclusively proven or disproven. This state of uncertainty not only clouds our knowledge of one-dimensional nucleon structure but also poses a major concern for our field's efforts to map out the three-dimensional nuclear structure. A better understanding of multi-photon exchange over a wide phase space is needed. We propose making comprehensive measurements of two-photon exchange over a wide range in momentum transfer and scattering angle using the CLAS12 detector. Specifically, we will measure the ratio of positron-proton to electron-proton elastic scattering cross sections, using the proposed positron beam upgrade for CEBAF. The experiment will use 2.2, 4.4, and 6.6 GeV lepton beams incident on the standard CLAS12 unpolarized hydrogen target. Data will be collected by the CLAS12 detector in its standard configuration, except for a modified trigger to allow the recording of events with beam leptons scattered into the CLAS12 central detector. The sign of the beam charge, as well as the polarity of the CLAS12 solenoid and toroid, will be reversed several times in order to suppress systematics associated with local detector efficiency and time-dependent detector performance. The proposed high-precision determination of two-photon effects will be...Comment: Experimental Proposal E12+23-008 submitted to Jefferson Lab PAC 51, 34 pages, 18 figure

Hemocompatibility of Silicon-Based Substrates for Biomedical Implant Applications

Silicon membranes with highly uniform nanopore sizes fabricated using microelectromechanical systems (MEMS) technology allow for the development of miniaturized implants such as those needed for renal replacement therapies. However, the blood compatibility of silicon has thus far been an unresolved issue in the use of these substrates in implantable biomedical devices. We report the results of hemocompatibility studies using bare silicon, polysilicon, and modified silicon substrates. The surface modifications tested have been shown to reduce protein and/or platelet adhesion, thus potentially improving biocompatibility of silicon. Hemocompatibility was evaluated under four categories—coagulation (thrombin–antithrombin complex, TAT generation), complement activation (complement protein, C3a production), platelet activation (P-selectin, CD62P expression), and platelet adhesion. Our tests revealed that all silicon substrates display low coagulation and complement activation, comparable to that of Teflon and stainless steel, two materials commonly used in medical implants, and significantly lower than that of diethylaminoethyl (DEAE) cellulose, a polymer used in dialysis membranes. Unmodified silicon and polysilicon showed significant platelet attachment; however, the surface modifications on silicon reduced platelet adhesion and activation to levels comparable to that on Teflon. These results suggest that surface-modified silicon substrates are viable for the development of miniaturized renal replacement systems

Top-down social modulation of interpersonal observation-execution.

Cyclical upper limb movement can involuntarily deviate from its primary movement axis when the performer concurrently observes incongruent biological motion (i.e. interpersonal observation-execution). The current study examined the social modulation of such involuntary motor interference using a protocol that reflected everyday social interactions encountered in a naturalistic social setting. Eighteen participants executed cyclical horizontal arm movements during the observation of horizontal (congruent) or curvilinear (incongruent) biological motion. Both prior to, and during the interpersonal observation-execution task, participants also received a series of social words designed to prime a pro-social or anti-social attitude. The results showed greater orthogonal movement deviation, and thus interference, for the curvilinear compared to horizontal stimuli. Importantly, and opposite to most of the previous findings from work on automatic imitation and mimicry, there was a greater interference effect for the anti-social compared to pro-social prime condition. These findings demonstrate the importance of interpreting the context of social primes, and strongly support predictions of a comparison between the prime construct and the self-concept/-schema and the top-down response modulation of social incentives