Investigation of the stimulation capabilities of a high-resolution neurorecording probe for the application of closed-loop deep brain stimulation

Deep brain stimulation is an established surgical treatment for several neurological and movement disorders, such as Parkinson's disease, in which electrostimulation is applied to targeted deep nuclei in the basal ganglia through implanted electrode leads. Recent technological improvements in the field have focused on the theoretical advantage of current steering and adaptive (closed-loop) deep brain stimulation. Current steering between several active electrodes would allow for improved accuracy when targeting the desired brain structures. This has the additional benefit of avoiding undesired stimulation of neural tracts that are related to side effects, e.g., internal capsule fibres of passage in subthalamic nucleus deep brain stimulation. Closed-loop deep brain stimulation is based on the premise of continuous recording of a proxy for pathological neural activity (such as beta-band power of measured local field potentials in patients with Parkinson's disease) and accordingly adapting the used stimulus parameters. In this study, we investigate the suitability of an existing highresolution neurorecording probe for high-precision neurostimulation. If a subset of the probe's recording electrodes can be used for stimulation, then the probe would be a suitable candidate for closed-loop deep brain stimulation. A finiteelement model is used to calculate the electric potential, induced by current injection through the high-resolution probe, for different sets of active electrodes. Volumes of activated tissue are calculated and a comparison is made between the highresolution probe and a conventional stimulation lead. We investigate the capability of the probe to shift the volume of activated tissue by steering currents to different sets of active electrodes. Finally, safety limits for the injected current are used to determine the size of the volume in which neurons can be activated with the relatively small electrodes patches on the highresolution probe

Microscopic State of Polymer Network Chains upon Swelling and Deformation

We use low-resolution proton NMR to probe the chain deformation in swollen and nonlinearly deformed vulcanized rubber and end-linked PDMS networks on a microscopic level, extending earlier work focusing on uniaxial stretching and isotropic dilation upon swelling toward biaxial deformation and deformation of swollen samples. Previous studies have revealed that chain deformation in bulk samples is best described by tube models, and that chains in swollen samples deform affinely after an initial desinterspersion stage, upon which entanglement-related packing effects are relieved. We test whether a subsequent deformation may also be closer to affine, and find that this is not the case. Unexpectedly, nonisotropic deformation of swollen samples also follows tube-model predictions, which is explained by a dominance of structural inhomogeneities and significant reorganization of the topological constraints active in the swollen and possibly even the bulk state.Fil: Naumova, Anna. Martin Luther Universität Halle Wittenberg; AlemaniaFil: Agudelo Mora, Diana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Villar, Marcelo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Vega, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Valentin, Juan Lopez. Instituto en Ciencia y Tecnología de Polímeros; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Saalwächter, Kay. Martin Luther Universität Halle Wittenberg; Alemani

A neural probe with up to 966 electrodes and up to 384 configurable channels in 0.13 μm SOI CMOS

In vivo recording of neural action-potential and local-field-potential signals requires the use of high-resolution penetrating probes. Several international initiatives to better understand the brain are driving technology efforts towards maximizing the number of recording sites while minimizing the neural probe dimensions. We designed and fabricated (0.13-μm SOI Al CMOS) a 384-channel configurable neural probe for large-scale in vivo recording of neural signals. Up to 966 selectable active electrodes were integrated along an implantable shank (70 μm wide, 10 mm long, 20 μm thick), achieving a crosstalk of −64.4 dB. The probe base (5 × 9 mm2) implements dual-band recording and a 1

A 128-channel real-time VPDNN stimulation system for a visual cortical neuroprosthesis

With the recent progress in developing large-scale micro-electrodes, cortical neuroprotheses supporting hundreds of electrodes will be viable in the near future. We describe work in building a visual stimulation system that receives camera input images and produces stimulation patterns for driving a large set of electrodes. The system consists of a convolutional neural network FPGA accelerator and a recording and stimulation Application-Specific Integrated Circuit (ASIC) that produces the stimulation patterns. It is aimed at restoring visual perception in visually impaired subjects. The FPGA accelerator, VPDNN, runs a visual prosthesis network that generates an output used to create stimulation patterns, which are then converted by the ASIC into current pulses to drive a multi-electrode array. The accelerator exploits spatial sparsity and the use of reduced bit precision parameters for reduced computation, memory and power for portability. Experimental results from the VPDNN show that the 94.5K parameter 14-layer CNN receiving an input of 128 × 128 has an inference frame rate of 83 frames per sec (FPS) and uses only an incremental power of 0.1 W, which is at least 10× lower than that measured from a Jetson Nano. The ASIC adds a maximum delay of 2ms, however it does not impact the FPS thanks to double-buffered memory. Index Terms—Visual prosthesis, convolutional neural network, FPGA Accelerator, stimulation and recording ASI

α-FAPbI3 powder presynthesized by microwave irradiation for photovoltaic applications

The development of up-scalable and high-throughput methodologies to fabricate high-efficiency lead halide perovskite solar cells (PSCs) based on α-phase formamidinium lead iodide (FAPbI3) is one of the main challenges of making solar energy economical. In this context, PSCs based on α-phase formamidinium lead iodide (FAPbI3) are receiving special attention as this perovskite has the highest theoretical photoconversion efficiency (PCE). This manuscript reports an easy, fast and environmentally-friendly way to prepare α-FAPbI3 black powders by a microwave-assisted synthesis and their application in solar cells. The α-FAPbI3 powders consist of micrometric particles that can be stored for weeks in a closed vial at ambient conditions. This technique presents an enormous potential for upscaling FAPbI3 powders synthesis prerequisite necessary for large scale commercialization. The performance of the presynthesized FAPbI3-based solar cell was comparable with that of PSCs fabricated with the conventional procedure from precursors solutions, leading to a maximum PCE value of 18.15%, with an VOC=1.07 V, a Jsc=24.28 mA/cm2 and an FF=70%. The presynthesized FAPbI3-based solar cell was further modified through the addition of methylammonium chloride (MACl) in order to study the generality of the approach. The optical band gap for the presynthesized perovskite shifted from ∼1.43 eV to ∼1.55 eV with the MACl addition (30 mol%), indicating the formation of a mixed methylammonium and formamidinium based perovskite material (MAFAPbI3). In addition, the incorporation of MACl led to an increase in the grain size and the disappearance of the residual δ-phase perovskite, thus improving the efficiency of the final device.Funding for open access charge: CRUE-Universitat Jaume

Post-transplant renal anaemia: a call to action from a national study in routine clinical practice

Background Post-transplant anemia is a prevalent yet often overlooked condition that poses significant risks. Current guidelines consider the same treatment recommendations and goals for these patients as for chronic kidney disease patients not on dialysis. Previous reports demonstrated a lack of awareness and suboptimal management, indicating a pressing need for improvement. We therefore wanted to update the information on post-transplant anemia. We aimed to describe the present state of anemia management, goals and adherence to guidelines within a representative sample of the kidney transplant (KTx) population.Methods We designed a retrospective nationwide multicenter study including outpatients from eight KTx hospitals. Nephrologists gathered data from electronic medical records encompassing demographics, comorbidities, KTx characteristics and immunosuppressive therapy, and information pertaining to anemia management (laboratory values, previously prescribed treatments and subsequent adjustments). The European statement on the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines was the reference for definitions, drug prescriptions and targets. Anemia occurring within the initial 6 months post-transplantation was classified as early onset.Results We included 297 patients with post-transplant anemia aged 62.8 years (standard deviation 13.6), 60% of whom were male. They had received a graft from cardiac death or brain death donors (61.6% and 31.1%, respectively) a median of 2.5 years (0.5-8.7) before. Among them 77% (n = 228) were classified as having late post-transplant anemia, characterized by a higher prevalence of microcytic and iron deficiency anemia. A total of 158 patients were on erythropoietic-stimulating agents (ESAs) treatment, yet surprisingly 110 of them lacked iron supplementation. Notably, 44 patients had an indication for iron supplementation and among them, 30 exhibited absolute iron deficiency. Out of the 158 patients receiving ESAs, only 39 surpassed the limit for the ESA resistance index, indicating poor response. This resistance was more frequent among patients with early post-transplant anemia (26.1% vs 9.2%). We have identified iron profile, early post-transplant anemia and estimated glomerular filtration rate as factors associated with the highest risk of resistanceConclusion We found that hemoglobin targets are individualized upwards in post-transplant anemia. In this setting, iron therapy continues to be underutilized, especially intravenous, and iron deficiency and prior events (blood transfusion or hospital admission) explain most of the hyporesponsiveness to ESA. This highlights missed opportunities for precise prescription targeting and adherence to established guidelines, suggesting a need for improved management strategies in post-transplant anemia patients

Use of High-Flow Cannula in Pediatric Patients With Respiratory Failure: A Prospective Cohort Study in Three High-Altitude Hospitals

BACKGROUND AND AIMS: Acute respiratory failure (ARF) is a common cause of morbimortality, and a frequent reason for admission to the pediatric intensive care unit (PICU). It requires a high-flow oxygen device as treatment. Our aim is to determine the frequency and main indications for the use of high-flow nasal cannula (HFNC), and the prevalence of HFNC failure and its main causes, in three hospitals. METHODS: It is a multicenter prospective cohort study, developed in three hospitals in Bogota. Eligible patients were children older than 1 month and younger than 18 years who presented ARF and required management with an HFNC. The study was carried out between April 2020 and December 2021. The follow-up was carried out at 1, 6, and 48 h after starting the management. RESULTS: Of 685 patients included in the study, 296 developed ARF. The prevalence of patients with ARF who required management with HFNC was 48%. The frequency of the pathologies that cause the ARF was: Bronchiolitis was the most frequent pathology (34.5%), followed by asthmatic crisis (15.5%) and pneumonia (12.7%). The average time of use of HFNC was 81.6 h. Regarding treatment failure with HFNC, 15 patients presented torpid evolution and required invasive mechanical ventilation, with a prevalence of therapeutic failure of the HFNC of 10.6%. CONCLUSION: The use of HFNC is more frequent in patients with bronchiolitis, in children under 2 years of age and in males, which is in line with what has been reported in the literature. In addition, the failure rate of HFNC is low (10.6%), and it may be useful in other pathologies besides bronchiolitis, such as asthma, pneumonia, among others. It opens the possibility to continue evaluating the role of HFNC in pediatric pathology in new studies

Use of High-Flow Cannula in Pediatric Patients with Respiratory Failure: A Prospective Cohort Study in Three High-Altitude Hospitals

BACKGROUND AND AIMS: Acute respiratory failure (ARF) is a common cause of morbimortality, and a frequent reason for admission to the pediatric intensive care unit (PICU). It requires a high-flow oxygen device as treatment. Our aim is to determine the frequency and main indications for the use of high-flow nasal cannula (HFNC), and the prevalence of HFNC failure and its main causes, in three hospitals. METHODS: It is a multicenter prospective cohort study, developed in three hospitals in Bogota. Eligible patients were children older than 1 month and younger than 18 years who presented ARF and required management with an HFNC. The study was carried out between April 2020 and December 2021. The follow-up was carried out at 1, 6, and 48 h after starting the management. RESULTS: Of 685 patients included in the study, 296 developed ARF. The prevalence of patients with ARF who required management with HFNC was 48%. The frequency of the pathologies that cause the ARF was: Bronchiolitis was the most frequent pathology (34.5%), followed by asthmatic crisis (15.5%) and pneumonia (12.7%). The average time of use of HFNC was 81.6 h. Regarding treatment failure with HFNC, 15 patients presented torpid evolution and required invasive mechanical ventilation, with a prevalence of therapeutic failure of the HFNC of 10.6%. CONCLUSION: The use of HFNC is more frequent in patients with bronchiolitis, in children under 2 years of age and in males, which is in line with what has been reported in the literature. In addition, the failure rate of HFNC is low (10.6%), and it may be useful in other pathologies besides bronchiolitis, such as asthma, pneumonia, among others. It opens the possibility to continue evaluating the role of HFNC in pediatric pathology in new studies