Feeling of control of an action after supra and subliminal haptic distortions.

Here we question the mechanisms underlying the emergence of the feeling of control that can be modulated even when the feeling of being the author of one's own action is intact. With a haptic robot, participants made series of vertical pointing actions on a virtual surface, which was sometimes postponed by a small temporal delay (15 or 65 ms). Subjects then evaluated their subjective feeling of control. Results showed that after temporal distortions, the hand-trajectories were adapted effectively but that the feeling of control decreased significantly. This was observed even in the case of subliminal distortions for which subjects did not consciously detect the presence of a distortion. Our findings suggest that both supraliminal and subliminal temporal distortions that occur within a healthy perceptual-motor system impact the conscious experience of the feeling of control of self-initiated motor actions.

Towards virtual reality exposure therapy for cocaine use disorder: A feasibility study of inducing cocaine craving through virtual reality.

Background: Craving is a core symptom of cocaine use disorders (CUD). Inducing craving in exposure to substance cues is of relevant interest for numerous clinical applications. Virtual reality exposure (VRE) might be a promising candidate for improving cue-exposure paradigms but remains almost not studied for cocaine. This feasibility study's main aim is to assess whether VRE to cocaine cues is capable to induce cocaine craving compared with VRE to neutral cues. Methods: We conducted a within-subjects controlled trial in which cocaine users performed 3 consecutive 10 mins-tasks: VRE to neutral and cocaine cues, and a relaxation-based resting procedure. The primary outcome was the change in Cocaine Craving Questionnaire-Brief (CCQ-Brief) scores between VRE to neutral and cocaine cues. Secondary outcomes included between-tasks changes in scores of cocaine craving, pleasant/unpleasant emotions as well as self-efficacy to cope with craving. Results: We recruited 11 chronic cocaine users including mostly crack smokers (45 %), cocaine snorters (36 %) and injectors (18 %), with 73 % of participants meeting DSM-IV criteria for cocaine dependence and/or abuse. Non-parametrical sign tests indicated significant large increases of CCQ-Brief scores from neutral to cocaine cue-VRE (S(11) = 11, p < 0.01, Cliff's Δ = 0.65, 95 % CI: 0.17-0.88). Exploratory comparative analyses indicated significant changes after our post-cues VRE relaxation procedure, with cocaine craving and emotions restored to baseline. Conclusions: VRE to cocaine cues was feasible and capable to induce cocaine craving in cocaine users. This second VRE-based cue-reactivity study in cocaine paves the way for unexplored research on VRE clinical applications for CUD.

Virtual reality cue-exposure therapy in reducing cocaine craving: the Promoting Innovative COgnitive behavioral therapy for Cocaine use disorder (PICOC) study protocol for a randomized controlled trial.

BACKGROUND: Cocaine craving is a central symptom of cocaine use disorders (CUD). Virtual reality cue-exposure therapy for craving (VRCET) allows more immersive, realistic, and controllable exposure than traditional non-VR cue-exposure therapy (CET), whose efficacy is limited in treating substance use disorders. The purpose of this study is to evaluate the efficacy and acceptability of VRCET, as a stand-alone and add-on intervention (i.e., combined with cognitive therapy), compared to a picture-based CET (PCET), in reducing self-reported cocaine craving in inpatients hospitalized for CUD. METHODS: Fifty-four inpatients hospitalized for CUD will be randomized in one of two intensive 3-week treatment arms: 10 meetings/2-week treatment of VRCET plus 5 meetings/1-week treatment of memory-focused cognitive therapy (MFCT; experimental arm), or 15 meetings/3-week treatment of PCET (active control arm). The Craving Experience Questionnaire (CEQ - F & S) will be used to assess the primary outcome, i.e., the post-treatment decrease of self-reported cocaine craving frequency (within the past 2 weeks) and intensity scores (in VR exposure to cocaine cues). Secondary endpoints include urinary, physiological, and self-reported cocaine use-related measures. Assessments are scheduled at pretreatment, after 2 weeks of treatment (i.e., VRCET vs. PCET), post-treatment (3 weeks, i.e., VRCET + MFCT vs. PCET), and at 1-month follow-up. Acceptability will be evaluated via (i) the Spatial Presence for Immersive Environments - Cybersickness along VRCET and (ii) the Client Satisfaction Questionnaires after 2 weeks of treatment and post-treatment. DISCUSSION: This study will be the first to evaluate the acceptability and efficacy of VRCET for CUD, as a psychotherapeutic add-on, to reduce both cocaine craving frequency and intensity. Additionally, this study will provide evidence about the specific interest of VRCET, compared to a non-VR-based CET, as a cue reactivity and exposure paradigm for treating substance use disorders. TRIAL REGISTRATION: NCT05833529 [clinicaltrials.gov]. Prospectively registered on April 17, 2023.

Graphene sustained nonlinear modes in dielectric waveguides.

We discuss the existence of nonlinear modes sustained by graphene layers in dielectric waveguides. Taking advantage of the almost two dimensional nature of graphene, we introduce the nonlinear effect as a parameter in the continuity equations. We then apply our modeling to a simple slab waveguide to enlighten how graphene can be used to induce huge nonlinear phase shifts at easily accessible power levels.

Graphene-assisted control of coupling between optical waveguides.

The unique properties of optical waveguides electrically controlled by means of graphene layers are investigated. We demonstrate that, thanks to tunable losses induced by graphene layers, a careful design of silicon on silica ridge waveguides can be used to explore passive PT-symmetry breaking in directional couplers. We prove that the exceptional point of the system can be probed by varying the applied voltage and we thus propose very compact photonic structures which can be exploited to control coupling between waveguides and to tailor discrete diffraction in arrays.

Graphene-assisted critically-coupled optical ring modulator.

Graphene's conductivity at optical frequencies can be varied upon injection of carriers. In the present paper, this effect is used to modulate losses of an optical wave traveling inside a ring cavity. This way an optical modulator based on the critical-coupling concept first introduced by Yariv can be realized. Through numerical simulations, we show that a modulator featuring a bandwidth as large as 100 GHz can be designed with switching energy in the order of few fJ per bit. Also, we show that operations with driving voltages below 1.2 volt could be obtained, thus making the proposed modulator compatible with requirements of low-voltage CMOS technology.

Volatility of subliminal haptic feedback alters the feeling of control in schizophrenia.

It has been proposed that agency disorders found in schizophrenia rely on aberrant processing of prediction error. Overreactivity to nonpertinent prediction errors may lead to the attribution of one's own actions to an external source. When applied to perception, this could explain hallucinations. However, experiments in motor control or perception have mainly suggested deficient prediction errors. Using a novel approach based on the manipulation of temporal delays, 23 patients with schizophrenia, 18 patients with bipolar disorder, and 22 healthy participants performed a pointing task with a haptic device that provided haptic feedback without or with delays, which were processed consciously (65 ms) or unconsciously (15 ms). The processing of prediction errors was measured via the adaptation of the hand trajectory, that is, the deceleration in anticipation of the surface, and its modulation as a function of recent history (stable or unstable sensory feedback). Agency was evaluated by measuring the participants' feeling of controlling the device. Only patients with schizophrenia reported a decrease in the feeling of control following subliminally delayed haptic feedback and adapted deceleration durations following subliminally delayed haptic feedback. This effect was correlated with positive symptoms. The overreactivity to subliminal delays was present only when delays occurred repeatedly in an unpredictable way, that is, with a volatile distribution. The results suggest that small temporal uncertainties that should be held as negligible, trigger an aberrant overreactivity which could account for hallucinations and alterations of the patients' conscious feeling of control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Modeling of enhanced field confinement and scattering by optical wire antennas.

We describe the application of full-wave and semi-analytical numerical tools for the modeling of optical wire antennas, with the aim of providing novel guidelines for analysis and design. The concept of antenna impedance at optical frequencies is reviewed by means of finite-element simulations, whereas a surface-impedance integral equation is derived in order to perform an accurate and efficient calculation of the current distribution, and thereby to determine the equivalent-circuit parameters. These are introduced into simple circuits models, directly borrowed from radio frequency, which are applied in order to model the phenomena of enhanced field confinement at the feed gap and light scattering by optical antennas illuminated by plane waves.

Efficacy and Tolerability of Ketotifen in the Treatment Of Seasonal Allergic Conjunctivitis: Comparison between Ketotifen 0.025% and 0.05% Eye Drops.

Purpose: To study the tolerability and efficacy of two formulations of topical ketotifen ophthalmic solutions for the treatment of seasonal allergic conjunctivitis (SAC).Methods: 81 active SAC patients were treated with either ketotifen 0.025% or 0.05% eye drops for 3 weeks. Allergic signs and symptoms were evaluated at baseline (V0), after 7 (V1) and 21 days (V2). Drugs tolerability and ratings of global efficacy were recorded.Results: Both concentrations of ketotifen were highly effective. The total signs and symptoms scores (TSSS) were significantly better reduced by ketotifen 0.025% compared to 0.05% at both V1 and V2 (p < 0.001). Ketotifen 0.025% was better tolerated than 0.05% at the first instillation and at days 2, 4, and 6 (p < 0.0001), and had a better responder rate (p < 0.001) according to the patient's and investigator's assessments.Conclusions: Ketotifen 0.025% was more effective and better tolerated than 0.05% in SAC.

Statistical study of parameters for deep brain stimulation automatic preoperative planning of electrodes trajectories.

PURPOSE: Automatic methods for preoperative trajectory planning of electrodes in deep brain stimulation are usually based on the search for a path that resolves a set of surgical constraints to propose an optimal trajectory. The relative importance of each surgical constraint is usually defined as weighting parameters that are empirically set beforehand. The objective of this paper is to analyze the use of these parameters thanks to a retrospective study of trajectories manually planned by neurosurgeons. For that purpose, we firstly retrieved weighting factors allowing to match neurosurgeons manually planned choice of trajectory on each retrospective case; secondly, we compared the results from two different hospitals to evaluate their similarity; and thirdly, we compared the trends to the weighting factors empirically set in most current approaches. METHODS: To retrieve the weighting factors best matching the neurosurgeons manual plannings, we proposed two approaches: one based on a stochastic sampling of the parameters and the other on an exhaustive search. In each case, we obtained a sample of combinations of weighting parameters with a measure of their quality, i.e., the similarity between the automatic trajectory they lead to and the one manually planned by the surgeon as a reference. Visual and statistical analyses were performed on the number of occurrences and on the rank means. RESULTS: We performed our study on 56 retrospective cases from two different hospitals. We could observe a trend of the occurrence of each weight on the number of occurrences. We also proved that each weight had a significant influence on the ranking. Additionally, we observed no influence of the medical center parameters, suggesting that the trends were comparable in both hospitals. Finally, the obtained trends were confronted to the usual weights chosen by the community, showing some common points but also some discrepancies. CONCLUSION: The results tend to show a predominance of the choice of a trajectory close to a standard direction. Secondly, the avoidance of the vessels or sulci seems to be sought in the surroundings of the standard position. The avoidance of the ventricles seems to be less predominant, but this could be due to the already reasonable distance between the standard direction and the ventricles. The similarity of results between two medical centers tends to show that it is not an exceptional practice. These results suggest that manual planning software may introduce a bias in the planning by proposing a standard position.

Noise evolution and soliton internal modes in dispersion-managed fiber systems.

We perform a linear stability analysis of the Ablowitz-Biondini equations to explain the dynamic evolution of the noise squeezing, caused by the interplay among optical solitons and noise components, of initially uncorrelated statistics in fiber systems with dispersion management.

Comunicación interauricular y embarazo: reporte de un caso / Interauricular shunt in pregnancy: case report

La comunicación intraauricular es la patología congénita más frecuente que se detecta en la edad adulta, siendo más observable en las mujeres, ocupando el tercer lugar entre todas las cardiopatías congénitas precedida por la comunicación interventricular y el ductus. El presente trabajo se trata de una paciente portadora de comunicación interauricular que se diagnostica durante su cuarto embarazo, debido a la sintomatología presentada y la evolución que tuvo hasta la resolución de su embarazo y de su alteración cardiológica...

Cardiopatías congénitas en el adulto: Tetralogía de Fallot / Congenital heart diseases in adults: tetralogy of Fallot

Presentamos el caso clínico de paciente masculino, quien presenta desde la infancia crisis de disnea, pero es en edad adulta en que su cuadro se vuelve más florido, sin presentar cianosis, viene a esta casa asistencial donde se le diagnostica Tetralogía de Fallot. Lo importante de la descripción de este caso, es que este tipo de patología pertenece al grupo de las cardiopatías congénitas cianosantes, pero hay un reducido número de pacientes que no presentan cianosis y son llamados Fallot rosados, como el que describimos a continuación.