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In this work, analysis and simulation of all experimentally observed switching modes in hafnium oxide based resistive random access memories are carried out using a simplified electrical conduction model. To achieve switching mode variation, two metal-insulator-metal cells with identical stack combination, but varying oxygen stoichiometry of the hafnia layer, namely, stoichiometric vs highly deficient, are considered. To access the individual switching modes, the devices were subjected to a variety of cycling conditions comprising different voltage and current ranges. For modeling the device behavior, a single or two antiserially connected memdiodes (diode with memory) were utilized. In this way, successful compact simulation of unipolar, bipolar, threshold, and complementary resistive switching modes is accomplished confirming the coexistence of two switching mechanisms of opposite polarity as the basis for all observable switching phenomena in this material. We show that only calibration of the outer current–voltage loops with the memdiode model is necessary for predicting the device behavior in the defined region revealing additional information on the switching process. The correspondence of each memdiode device with the conduction characteristics of the individual top and bottom metal-oxide contacts allows one to assess the role played by each interface in the switching process separately. This identification paves the path for a future improvement of the device performance and functionality by means of appropriate interface engineering. [ABSTRACT FROM AUTHOR]

The angular wavelet analysis is applied for assessing the spatial distribution of breakdown spots in Pt/HfO2/Pt capacitors with areas ranging from 104 to 105 μm². The breakdown spot lateral sizes are in the range from 1 to 3 μm, and they appear distributed on the top metal electrode as a point pattern. The spots are generated by ramped and constant voltage stresses and are the consequence of microexplosions caused by the formation of shorts spanning the dielectric film. This kind of pattern was analyzed in the past using the conventional spatial analysis tools such as intensity plots, distance histograms, pair correlation function, and nearest neighbours. Here, we show that the wavelet analysis offers an alternative and complementary method for testing whether or not the failure site distribution departs from a complete spatial randomness process in the angular domain. The effect of using different wavelet functions, such as the Haar, Sine, French top hat, Mexican hat, and Morlet, as well as the roles played by the process intensity, the location of the voltage probe, and the aspect ratio of the device, are all discussed. [ABSTRACT FROM AUTHOR]

BackgroundFear-avoidance in COPD can have detrimental effects on pulmonary rehabilitation (PR) outcomes and is therefore important to address. This prospective study examined changes in and management of COPD-related anxiety symptoms over the course of a PR program.MethodsPatients with COPD referred to 9-weeks of PR in the municipality of Vejle, Denmark from January to December 2022 completed a six-minute walk test (6MWT) and the following questionnaires, both before and after PR: COPD Anxiety Questionnaire 20-item version (CAF-R), measuring COPD-related anxiety; COPD Assessment Test (CAT), measuring COPD-related disability; 12-Item Short-Form Health Survey (SF-12), measuring health-related quality of life (HR-QoL); sociodemographic and disease-related information. After PR, a subsample of the patients took part in semi-structured interviews exploring their understanding of how they managed COPD-related anxiety during PR. Pre- and post-assessment of COPD-related anxiety and other PR outcomes were analysed with t-tests and correlation analyses. Qualitative interviews were analysed using a thematic analysis approach.ResultsA total of 72 patients with COPD (mean ± SD age 71 ± 8, 53% female) were included in the study, and 13 took part in qualitative interviews. A significant decrease in COPD-related anxiety was observed from before to after PR, corresponding to a small effect size (Cohen's d = 0.32; p = 0.018). Reductions in COPD-related anxiety were not associated with improvements in COPD-related disability, HR-QOL, or functional exercise capacity. The qualitative findings identified four anxiety management strategies, i.e., “planning”, “problem-solving”, “accepting”, and “confronting”, which were influenced by interactions with healthcare professionals and co-patients as well as patients’ own perception.ConclusionsCOPD-related anxiety symptoms was reduced after PR, potentially through the use of various management strategies. The strategies appeared to be influenced by interactional factors during the PR program.

The hysteretic conduction characteristics and fatigue profile of La1/3Ca2/3MnO3 (LCMO)-based memristive devices were investigated. The oxide films were grown by pulsed laser deposition (PLD) and sandwiched between Ag and Pt electrodes. The devices exhibit bipolar resistive switching (RS) effect with well-defined intermediate conduction states that arise from partial SET and RESET events. The current-voltage curves are modeled and simulated using a compact memristive approach. Two equations are considered: one for the electron transport based on the double-diode equation and the other for the memory state of the device driven by the play operator with logistic ridge functions. An expression that accounts for the remnant resistance of the device is obtained after simplifying the model equations in the low-voltage limit. The role played by the power dissipation in the LCMO reset dynamics as well as the asymmetrical reduction of the resistance window caused by long trains of switching pulses are discussed. [ABSTRACT FROM AUTHOR]

Abstract Objective: This review aimed to identify and synthesise the enablers and barriers that influence the long-term (≥ 2 years) sustainment of school-based nutrition programmes. Design: Four databases (PubMed, Cochrane Library, Embase and Scopus) were searched to identify studies reporting on the international literature relating to food and nutrition programmes aimed at school-age (5–14 years) children that had been running for ≥ 2 years (combined intervention and follow-up period). Eligible studies were analysed using the Integrated Sustainability Framework (ISF), which involved deductive coding of programme enablers and barriers. A quality assessment was completed, using the Mixed-Methods Appraisal Tool and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Setting: International school-based nutrition programmes. Subjects: Individuals involved with the implementation of school-based nutrition programmes. Results: From the 7366 articles identified, thirteen studies (seven qualitative, five mixed methods and one quantitative descriptive) were included, from which the enablers and barriers of eleven different nutrition-related programmes were analysed. Thirty-four factors across the five domains of the ISF were identified that influenced the sustained implementation of programmes. The most common barrier was a lack of organisational readiness and resources, whereas the most common enabler was having adequate external partnerships and a supportive environment. Conclusions: These findings have application during the initiation and implementation phases of school-based nutrition programmes. Paying attention to the ‘outer contextual factors’ of the ISF including the establishment and maintenance of robust relationships across whole of government systems, local institutions and funding bodies are crucial for programme sustainment.

The FASER experiment at the LHC is designed to search for light, weakly-interacting particles produced in proton-proton collisions at the ATLAS interaction point that travel in the far-forward direction. The first results from a search for dark photons decaying to an electron-positron pair, using a dataset corresponding to an integrated luminosity of 27.0 fb−1 collected at centre-of-mass energy s=13.6 TeV in 2022 in LHC Run 3, are presented. No events are seen in an almost background-free analysis, yielding world-leading constraints on dark photons with couplings ϵ∼2×10−5−1×10−4 and masses ∼17 MeV−70 MeV. The analysis is also used to probe the parameter space of a massive gauge boson from a U(1)B−L model, with couplings gB−L∼5×10−6−2×10−5 and masses ∼15 MeV−40 MeV excluded for the first time.

An in-depth study of reset processes in RRAMs (Resistive Random Access Memories) based on Ni/HfO2/Si-n+ structures has been performed. To do so, we have developed a physically based simulator where both ohmic and tunneling based conduction regimes are considered along with the thermal description of the devices. The devices under study have been successfully fabricated and measured. The experimental data are correctly reproduced with the simulator for devices with a single conductive filament as well as for devices including several conductive filaments. The contribution of each conduction regime has been explained as well as the operation regimes where these ohmic and tunneling conduction processes dominate. [ABSTRACT FROM AUTHOR]

The generation and conduction state of breakdown spot patterns in HfO2-based metal-insulatormetal structures are investigated using transient infrared thermography in combination with spatial statistics. The spots are created at a low generation rate by applying an appropriate constant voltage stress to the devices. Because of the important thermal effects involved during degradation, the breakdown events leave their fingerprints on the top metal electrode in the form of two-dimensional point patterns. Contrary to what is expected, thermal mappings reveal that many of these failure sites do not longer conduct after their creation, which is consistent with a self-healing behavior. In order to investigate whether the local heat dissipation and thermal propagation induce spatial correlation among the failure events or not, the final breakdown spot spatial distributions are compared with simulations of homogeneous Poisson point processes in the plane and the results are validated against the smoothed residual field and quantile-quantile plots. [ABSTRACT FROM AUTHOR]