Charging of highly resistive granular metal films

We have used the Scanning Kelvin probe microscopy technique to monitor the charging process of highly resistive granular thin films. The sample is connected to two leads and is separated by an insulator layer from a gate electrode. When a gate voltage is applied, charges enter from the leads and rearrange across the sample. We find very slow processes with characteristic charging times exponentially distributed over a wide range of values, resulting in a logarithmic relaxation to equilibrium. After the gate voltage has been switched off, the system again relaxes logarithmically slowly to the new equilibrium. The results cannot be explained with diffusion models, but most of them can be understood with a hopping percolation model, in which the localization length is shorter than the typical site separation. The technique is very promising for the study of slow phenomena in highly resistive systems and will be able to estimate the conductance of these systems when direct macroscopic measurement techniques are not sensitive enough.Comment: 8 pages, 7 figure

Characterization of a raspberry Pi as the core for a low-cost multimodal EEG-fNIRS platform.

Poor understanding of brain recovery after injury, sparsity of evaluations and limited availability of healthcare services hinders the success of neurorehabilitation programs in rural communities. The availability of neuroimaging ca-pacities in remote communities can alleviate this scenario supporting neurorehabilitation programs in remote settings. This research aims at building a multimodal EEG-fNIRS neuroimaging platform deployable to rural communities to support neurorehabilitation efforts. A Raspberry Pi 4 is chosen as the CPU for the platform responsible for presenting the neurorehabilitation stimuli, acquiring, processing and storing concurrent neuroimaging records as well as the proper synchronization between the neuroimaging streams. We present here two experiments to assess the feasibility and characterization of the Raspberry Pi as the core for a multimodal EEG-fNIRS neuroimaging platform; one over controlled conditions using a combination of synthetic and real data, and another from a full test during resting state. CPU usage, RAM usage and operation temperature were measured during the tests with mean operational records below 40% for CPU cores, 13.6% for memory and 58.85 ° C for temperatures. Package loss was inexistent on synthetic data and negligible on experimental data. Current consumption can be satisfied with a 1000 mAh 5V battery. The Raspberry Pi 4 was able to cope with the required workload in conditions of operation similar to those needed to support a neurorehabilitation evaluation

Gaze patterns hold key to unlocking successful search strategies and increasing polyp detection rate in colonoscopy

BACKGROUND:  The adenoma detection rate (ADR) is an important quality indicator in colonoscopy. The aim of this study was to evaluate the changes in visual gaze patterns (VGPs) with increasing polyp detection rate (PDR), a surrogate marker of ADR. METHODS:  18 endoscopists participated in the study. VGPs were measured using eye-tracking technology during the withdrawal phase of colonoscopy. VGPs were characterized using two analyses - screen and anatomy. Eye-tracking parameters were used to characterize performance, which was further substantiated using hidden Markov model (HMM) analysis. RESULTS:  Subjects with higher PDRs spent more time viewing the outer ring of the 3 × 3 grid for both analyses (screen-based: r = 0.56, P = 0.02; anatomy: r = 0.62, P < 0.01). Fixation distribution to the "bottom U" of the screen in screen-based analysis was positively correlated with PDR (r = 0.62, P = 0.01). HMM demarcated the VGPs into three PDR groups. CONCLUSION:  This study defined distinct VGPs that are associated with expert behavior. These data may allow introduction of visual gaze training within structured training programs, and have implications for adoption in higher-level assessment

Memory effects in a gas of viscoelastic particles

We study a granular gas of viscoelastic particles (kinetic energy loss upon collision is a function of the particles' relative velocities at impact) subject to a stochastic thermostat. We show that the system displays anomalous cooling and heating rates during thermal relaxation processes, this causing the emergence of thermal memory. In particular, a significant Mpemba effect is present, i.e., an initially hotter/cooler granular gas can cool down/heat up faster than an in comparison cooler/hotter granular gas. Moreover, a Kovacs effect is also observed, i.e., a nonmonotonic relaxation of the granular temperature¿if the gas undergoes certain sudden temperature changes before fixing its value. Our results show that both memory effects have distinct features, very different and eventually opposed to those reported in theory for granular fluids under simpler collisional models. We study our system via three independent methods: approximate solution of the kinetic equation time evolution and computer simulations (both molecular dynamics simulations and direct simulation Monte Carlo method), finding good agreement between them.This work has been partially funded by the Spanish Ministerio de Ciencia, Innovación y Universidades and the Agencia Estatal de Investigación through Grant Nos. MTM2017-84446-C2–2-R (A.L., E.M., and A.T.), FIS2017-84440-C2–2-P (A.T.), and FIS2016-76359-P. (F.V.R.). M.A.L.C. and F.V.R. also acknowledge support from the regional Extremadura Government through Project Nos. GR18079 and IB16087. Computing facilities from the Extremadura Research Centre for Advanced Technologies (CETA-CIEMAT) are also acknowledged. All grants and facilities were provided with partial support from the ERDF

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

A clinical trial to compare the quality of life of HIV+ patients who start monotherapy with LPV/r versus continuing triple therapy with a boosted PI

Purpose of the study: Efficacy, toxicity and complexity of antiretroviral (ARV) regimens may impact the quality of life (QoL). Since over the past years the simplification approach of lopinavir/ritonavir (LPV/r) as monotherapy (MT) has been shown to be non-inferior to triple therapy (TT) in virological and immunological efficacy, the objective of this study was to compare several health- and treatment-related outcomes between both ARV strategies with LPV/r. Methods: A phase IV national, multicenter, controlled, randomized (2:1), open label, parallel-group clinical trial to compare the QoL in patients on ARV TT containing any boosted protease inhibitor (PI), undetectable viral load (VL&#60; 50 cop/mL) in the past 6 months and a CD4 nadir &#x003E; 100 cells/&#x00B5;L, versus those who were simplified to LPV/r MT, for 24 weeks. QoL and health outcomes were evaluated by the Medical Outcomes Study HIV Health Survey (MOS-HIV) and the five-dimensional EuroQol questionnaire (EQ-5D). Treatment satisfaction was assessed by the Spanish Questionnaire of Satisfaction with ARV Treatment (CESTA). Treatment adherence was assessed by the Spanish Multifactorial Adherence questionnaire (GEEMA) and a visual analog scale (VAS). Tolerability, safety and virological and immunological efficacy at week 24 were also analyzed. Summary of results: 225 patients from 29 sites were enrolled (MT: 146, 64.5%; TT: 79, 35.1%). Mean age (years) was 44.5 in MT and 45.2 in TT (p=0.745); mean duration (years) from HIV infection was 13.4 in MT and 12.8 in TT (p=0.587) and 71% were male in both arms. 87.6% of patients completed correctly the study (MT: 88.4%; TT: 86.1%; p=0.674). Health and treatment outcomes evaluated at final study visit are shown in figure 1 1. At study end, 84.1% in MT and 89.6% in TT had undetectable VL (p=0.313) and mean CD4 count were 742.8 cells/&#x00B5;L in MT and 646.5 cells/&#x00B5;L in TT (p=0.060). There were no significant differences in the percentage of patients with virological failure at week 24 as VL &#x003E;50 cop/mL (MT: 8.2%; TT: 3.9%; p=0.271) and as VL &#x003E;200 cop/mL (MT: 3.4%; TT: 0%; p=0.167). Conclusions: The MT simplification strategy with LPV/r maintains comparable virological and immunological efficacy, as well as the tolerability profile, than the TT. The saving resulting from NRTIs withdrawal from the ARV regimen and the good results on QoL and patients treatment satisfaction make MT strategy with LPV/r be taken into account in clinical practice