Investigating the variation of particle distribution and surface texture of top surfaces based on build position in laser powder bed fusion

Quality analysis of additively manufactured (AM) surfaces is complex, yet critical for determining the functionality of parts and technology improvement. To accurately assess the quality of AM parts, it is necessary to consider the industrial application of the technology. This study investigates the variation of accumulated particles on AM top surfaces as a function of build position. It also seeks to study the surface texture variation as a function of build position, focusing on a spatial bandwidth region larger than that of traditional AM surface features, such as weld tracks, to investigate surface tension effects. Ti-6Al-4V cubes were built in a three-by-three array in a single build with fixed processing parameters. Coherence scanning interferometry was used to capture the primary data of the as-built top surfaces of cubes. The ISO 25178-2 methodology was used to extract the S-L surfaces, using the filtration methods defined in ISO 16610-21. The number of particles, coverage, and density were obtained by averaging over five repeated measurements in five different areas on the top surfaces. Particle distribution and surface texture analysis showed a trend from one location to another across the build, which is discussed according to the process variations

Uniform cooling for concentrator photovoltaic cell by micro-encapsulated phase change material slurry in double-layered minichannels

The concentrator photovoltaic (CPV) systems often suffer high heat flux, leading to cell temperatures rising, which will affect its performance and reduce the service life. Double-layered minichannel heat sink (DL-MCHS) is an efficient cooling technology, which could effectively lower down the top temperature of CPV cell. Micro-encapsulated phase change material slurry (MPCS) is a novel type of latent heat functional fluid and has a good application prospect in the field of cooling. Therefore, MPCS flowing in the DL-MCHS, as the thermal management device was investigated for the cooling of CPV cell. Three configurations of minichannels, including staggered arrangement, parallel arrangement and dual unequal arrangement were compared and optimized. On the basis of optimization, the flow and heat transfer performance of MPCS with different concentrations in double-layered straight and wavy minichannels had been numerically studied. The results indicated that the lowest top temperature of dual unequal DL-MCHS obtained by counter arrangement could be reduced by 0.56 °C compared with the parallel arrangement at Re = 152. Both the ΔP and h were significantly influenced by concentrations. When Re reached 262, ΔP of 5 wt% MPCS in wave minichannel with 5 mm wavelength was 44 % larger than that of pure water in straight minichannel, which would consume more pumping power. However, the heat dissipation performance was improved significantly and Nusselt number in double-layered wavy minchannels also increased with the wavelength decreasing. Therefore, Performance Evaluation Criteria (PEC) was proposed to evaluate the overall performance, which was also greatly influenced by particle concentration and channel wavelength. After optimization, the highest PEC of MPCS in the wavy minichannel was achieved to 1.60. Because of the wavy minichannel with concave-convex structure, the obstacle of total thermal resistance became smaller for the wavelength decreasing. These findings of MPCS in minichannel can provide a good theoretical basis and engineering application in the cooling technology of CPV

Perceptions, definitions, and therapeutic interventions for occasional constipation: a ROME working group consensus document

Background & Aims: Functional constipation is the most common of the disorders of gut-brain interaction, affecting approximately 12% of the world population. Although classically considered a chronic condition, many individuals experience shorter yet repetitive bouts of constipation representing a different clinical entity. There has been increased interest in this latter disorder, which has recently been classified as occasional constipation. This Rome Foundation working group document reflects the consensus of an international team of specialists who summarized currently available research to provide a working definition of and treatment algorithm for occasional constipation. The recommendations herein are based on current evidence, accounting for gaps in the literature as well as international variance in definitions and health seeking behaviors for constipation. Methods: The committee members reviewed the scientific literature, focusing specifically on occasional constipation, with the understanding that as a new entity, a paucity of data would be available. We used Rome IV research and clinical definitions to establish the framework for our definition of occasional constipation. Where possible, treatment recommendations were determined on the basis of the earliest extractable data from functional constipation studies, focusing on positive results within the first 2 weeks of treatment. We used the Delphi method to create consensus with 100% agreement between the authors. Results: An evidence-based review of the literature resulted in the definition of occasional constipation as follows: “individuals who experience the presence of at least 1 functional constipation symptom, in the absence of alarm signs or symptoms, occurring at irregular and infrequent intervals, which is bothersome enough to induce a patient to seek medical management.” Medical management whether seeking medical care or self-treatment was left to the individual's discretion, and we did not include time anchors because these thresholds require further investigation. Polyethylene glycol and stimulant laxatives are recommended as first-line interventions, whereas magnesium-containing compounds are suggested in individuals failing to respond to these therapies. There are insufficient data to make recommendations for using fiber or stool softeners. Prescription laxatives should be reserved for individuals with chronic constipation. Conclusions: Occasional constipation is a unique clinical entity characterized by infrequent but recurrent symptoms. Data are limited because consensus definitions have been lacking. Establishing a standardized definition and therapeutic recommendations provides a framework for future studies focusing on epidemiologic and symptoms-based outcomes. Further studies are needed to confirm and refine these recommendations

Constructing selection hyper-heuristics for open vehicle routing with time delay neural networks using multiple experts

Hyper-heuristics are general purpose search methods for solving computationally difficult problems. A selection hyper-heuristic is composed of two key components: a heuristic selection method and move acceptance criterion. Under an iterative single-point search framework, a solution is modified by selecting and applying a predefined low-level heuristic, with a decision then taken to accept or reject the resulting solution. Designing a selection hyper-heuristic is an extremely challenging task. In this study, we investigate computer-aided design of a selection hyper-heuristic for the open vehicle routing problem. A time delay neural network is used as an offline apprenticeship learning method. Our approach first observes the search behaviour of multiple expert human-designed selection hyper-heuristics on a selected sample of training instances, before automatically generating a selection hyper-heuristic capable of solving unseen instances effectively. The proposed approach is tested on open vehicle routing problem instances of different sizes to examine the performance and generality of the selection hyper-heuristics generated. Improved performance is demonstrated over a set of well-known benchmarks from the literature when compared to using the existing expert systems directly

The 2022 symposium on dementia and brain aging in low‐ and middle‐income countries: Highlights on research, diagnosis, care, and impact

Two of every three persons living with dementia reside in low‐ and middle‐income countries (LMICs). The projected increase in global dementia rates is expected to affect LMICs disproportionately. However, the majority of global dementia care costs occur in high‐income countries (HICs), with dementia research predominantly focusing on HICs. This imbalance necessitates LMIC‐focused research to ensure that characterization of dementia accurately reflects the involvement and specificities of diverse populations. Development of effective preventive, diagnostic, and therapeutic approaches for dementia in LMICs requires targeted, personalized, and harmonized efforts. Our article represents timely discussions at the 2022 Symposium on Dementia and Brain Aging in LMICs that identified the foremost opportunities to advance dementia research, differential diagnosis, use of neuropsychometric tools, awareness, and treatment options. We highlight key topics discussed at the meeting and provide future recommendations to foster a more equitable landscape for dementia prevention, diagnosis, care, policy, and management in LMICs. Highlights: Two‐thirds of persons with dementia live in LMICs, yet research and costs are skewed toward HICs. LMICs expect dementia prevalence to more than double, accompanied by socioeconomic disparities. The 2022 Symposium on Dementia in LMICs addressed advances in research, diagnosis, prevention, and policy. The Nairobi Declaration urges global action to enhance dementia outcomes in LMICs

Impact of Vth Instability of Schottky-type p-GaN Gate HEMTs on Switching Behaviors

Schottky-type p-GaN gate Gallium Nitride High Electron Mobility Transistors (GaN-HEMTs) suffer from threshold voltage (Vth) instability phenomenon. Both positive and negative Vth shifts are reported when device undertakes the voltage bias, but the impact of this Vth instability phenomenon on device switching behaviors is less investigated. In this study, the drain-source voltage (Vds) induced bidirectional Vth shift in hard-switching condition is characterized and decoupled by an H-bridge based double-pulse test (DPT). Subsequently, the influence of Vth shift on switching behaviors is theoretically analyzed and demonstrated through SPICE simulation and experiment, showing how a positive shifted Vth can reduce the device turn-on commutation speed and increase the switching losses, and vice versa. The results suggest that the Vth instability phenomenon should be considered in accurate switching modeling

Impact of board diversity on Chinese firms’ cross-border M&A performance: An artificial intelligence approach

In this paper, we examine the impact of board demographic characteristics on Chinese firms’ cross-border Mergers and Acquisition (M&A) performance, especially the gender diversity of the board composition. We unveil that female board proportion exhibits a positive and significant effect on cross-border M&A performance. On the other hand, board member age diversity and board member education diversity play a trivial role on cross-border M&A performance. We further introduce an optimization model called Particle Swarm Optimization (PSO), which is an artificial intelligence technical application, to address the optimal board diversity regarding the M&A performance. We demonstrate that a better organized board structure, such as increasing female board presentation tend to improve cross-border M&A performance of Chinese firms. We argue that the enhanced performance from optimized board diversity might be transmitted through the channel of corporate governance. Furthermore, we reveal that the board diversity effect is stronger in private owned companies compared with state owned companies. Our results can thereby deliver implications of corporate governance

Measurement properties of tools used to assess self-harm in autistic and general population adults

Autistic people are at increased risk of experiencing self-harm compared to the general population. However, it is unclear which tools are being used to assess self-harm in autistic people, or whether existing tools need to be adapted for this group. This two-stage systematic review aimed to identify tools used to assess self-harm in autistic and general population adults, evaluate these tools on their measurement properties, and make recommendations for their appropriate use in research and clinical practice. Four databases were systematically searched (PsycINFO, Embase, MEDLINE and Web of Science). Eight frequently used self-harm assessment tools were identified and assessed for risk of bias, criteria for good measurement properties, and quality of evidence using the COSMIN checklist. Of these, two tools had sufficient evidence of internal consistency (ISAS, QNSSI), and one had been frequently used with autistic adults (NSSI-AT). These three tools may have potential for use with autistic adults but require further investigation for content validity and measurement properties in the autistic population. More research and potential adaptations to current self-harm assessment tools are recommended in order to better conceptualise and understand self-harm and its measurement in autism. [Abstract copyright: Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.

General Purpose Artificial Intelligence Systems (GPAIS): Properties, definition, taxonomy, societal implications and responsible governance

Most applications of Artificial Intelligence (AI) are designed for a confined and specific task. However, there are many scenarios that call for a more general AI, capable of solving a wide array of tasks without being specifically designed for them. The term General Purpose Artificial Intelligence Systems (GPAIS) has been defined to refer to these AI systems. To date, the possibility of an Artificial General Intelligence, powerful enough to perform any intellectual task as if it were human, or even improve it, has remained an aspiration, fiction, and considered a risk for our society. Whilst we might still be far from achieving that, GPAIS is a reality and sitting at the forefront of AI research. This work discusses existing definitions for GPAIS and proposes a new definition that allows for a gradual differentiation among types of GPAIS according to their properties and limitations. We distinguish between closed-world and open-world GPAIS, characterising their degree of autonomy and ability based on several factors such as adaptation to new tasks, competence in domains not intentionally trained for, ability to learn from few data, or proactive acknowledgement of their own limitations. We then propose a taxonomy of approaches to realise GPAIS, describing research trends such as the use of AI techniques to improve another AI (commonly referred to as AI-powered AI) or (single) foundation models. As a prime example, we delve into generative AI (GenAI), aligning them with the terms and concepts presented in the taxonomy. Similarly, we explore the challenges and prospects of multi-modality, which involves fusing various types of data sources to expand the capabilities of GPAIS. Through the proposed definition and taxonomy, our aim is to facilitate research collaboration across different areas that are tackling general purpose tasks, as they share many common aspects. Finally, with the goal of providing a holistic view of GPAIS, we discuss the current state of GPAIS, its prospects, implications for our society, and the need for regulation and governance of GPAIS to ensure their responsible and trustworthy development

Peer-led recovery groups for people with psychosis in South Africa (PRIZE): results of a randomized controlled feasibility trial

AimsThe aims of this feasibility trial were to assess the acceptability and feasibility of peer-led recovery groups for people with psychosis in a low-resource South African setting, to assess the feasibility of trial methods, and to determine key parameters in preparation for a definitive trial.MethodsThe design was an individually randomised feasibility trial comparing recovery groups in addition to treatment as usual (TAU) with TAU alone. Ninety-two isiXhosa-speaking people with psychosis and forty-seven linked caregivers were recruited from primary care clinics and randomly allocated to trial arms in a 1:1 allocation ratio. TAU comprised anti-psychotic medication delivered in primary care. The intervention arm comprised six recovery groups including service users and caregivers. Two-hour recovery group sessions were delivered weekly in a 2-month auxiliary social worker (ASW)-led phase, then a 3-month peer-led phase. To explore acceptability and feasibility, a mixed methods process evaluation included 25 in-depth interviews and 2 focus group discussions at 5 months with service users, caregivers and implementers, and quantitative data collection including attendance and facilitator competence. To explore potential effectiveness, quantitative outcome data (functioning, relapse, unmet needs, personal recovery, stigma, health service use, medication adherence and caregiver burden) were collected at baseline, 2 months and 5 months post randomisation. Trial registration: PACTR202202482587686.ResultsQualitative interviews revealed that recovery groups were broadly acceptable with most participants finding groups to be an enjoyable opportunity for social interaction, and joint problem-solving. Peer facilitation was a positive experience; however a minority of participants did not value expertise by lived experience to the same degree as expertise of professional facilitators. Attendance was moderate in the ASW-led phase (participants attended 59% sessions on average) and decreased in the peer-led phase (41% on average). Participants desired a greater focus on productive activities and financial security. Recovery groups appeared to positively impact on relapse. Relapse occurred in 1 (2.2%) of 46 participants in the recovery group arm compared to 8 (17.4%) of 46 participants in the control arm (risk difference -0.15 [95% CI: −0.26; −0.05]). Recovery groups also impacted on the number of days in the last month totally unable to work (mean 1.4 days recovery groups vs 7.7 days control; adjusted mean difference −6.3 [95%CI: −12.2; −0.3]). There were no effects on other outcomes.ConclusionPeer-led recovery groups for people with psychosis in South Africa are potentially acceptable, feasible and effective. A larger trial, incorporating amendments such as increased support for peer facilitators, is needed to demonstrate intervention effectiveness definitively