bluuebunny/crossref_metadata_2025 huggingface dataset:
TorchQL: A Programming Framework for Integrity Constraints in Machine Learning
Authors: Naik Aaditya , Stein Adam , Wu Yinjun , Naik Mayur , Wong Eric
Published: April 2024

Finding errors in machine learning applications requires a thorough exploration of their behavior over data. Existing approaches used by practitioners are often ad-hoc and lack the abstractions needed to scale this process. We present TorchQL, a programming framework to evaluate and improve the correctness of machine learning applications. TorchQL allows users to write queries to specify and check integrity constraints over machine learning models and datasets. It seamlessly integrates relational algebra with functional programming to allow for highly expressive queries using only eight intuitive operators. We evaluate TorchQL on diverse use-cases including finding critical temporal inconsistencies in objects detected across video frames in autonomous driving, finding data imputation errors in time-series medical records, finding data labeling errors in real-world images, and evaluating biases and constraining outputs of language models. Our experiments show that TorchQL enables up to 13x faster query executions than baselines like Pandas and MongoDB, and up to 40% shorter queries than native Python. We also conduct a user study and find that TorchQL is natural enough for developers familiar with Python to specify complex integrity constraints.
Distributions for Compositionally Differentiating Parametric Discontinuities
Authors: Michel Jesse , Mu Kevin , Yang Xuanda , Bangaru Sai Praveen , Collins Elias Rojas , Bernstein Gilbert , Ragan-Kelley Jonathan , Carbin Michael , Li Tzu-Mao
Published: April 2024

Computations in physical simulation, computer graphics, and probabilistic inference often require the differentiation of discontinuous processes due to contact, occlusion, and changes at a point in time. Popular differentiable programming languages, such as PyTorch and JAX, ignore discontinuities during differentiation. This is incorrect for
parametric discontinuities
—conditionals containing at least one real-valued parameter and at least one variable of integration. We introduce Potto, the first differentiable first-order programming language to soundly differentiate parametric discontinuities. We present a denotational semantics for programs and program derivatives and show the two accord. We describe the implementation of Potto, which enables separate compilation of programs. Our prototype implementation overcomes previous compile-time bottlenecks achieving an 88.1x and 441.2x speed up in compile time and a 2.5x and 7.9x speed up in runtime, respectively, on two increasingly large image stylization benchmarks. We showcase Potto by implementing a prototype differentiable renderer with separately compiled shaders.
Deriving Dependently-Typed OOP from First Principles
Authors: Binder David , Skupin Ingo , Süberkrüb Tim , Ostermann Klaus
Published: April 2024

The
expression problem
describes how most types can easily be extended with new ways to
produce
the type or new ways to
consume
the type, but not both. When abstract syntax trees are defined as an algebraic data type, for example, they can easily be extended with new consumers, such as
print
or
eval
, but adding a new constructor requires the modification of all existing pattern matches. The expression problem is one way to elucidate the difference between functional or data-oriented programs (easily extendable by new consumers) and object-oriented programs (easily extendable by new producers). This difference between programs which are extensible by new producers or new consumers also exists for dependently typed programming, but with one core difference: Dependently-typed programming almost exclusively follows the functional programming model and not the object-oriented model, which leaves an interesting space in the programming language landscape unexplored. In this paper, we explore the field of dependently-typed object-oriented programming by
deriving it from first principles
using the principle of duality. That is, we do not extend an existing object-oriented formalism with dependent types in an ad-hoc fashion, but instead start from a familiar data-oriented language and derive its dual fragment by the systematic use of defunctionalization and refunctionalization. Our central contribution is a dependently typed calculus which contains two dual language fragments. We provide type- and semantics-preserving transformations between these two language fragments: defunctionalization and refunctionalization. We have implemented this language and these transformations and use this implementation to explain the various ways in which constructions in dependently typed programming can be explained as special instances of the general phenomenon of duality.
PyDex: Repairing Bugs in Introductory Python Assignments using LLMs
Authors: Zhang Jialu , Cambronero José Pablo , Gulwani Sumit , Le Vu , Piskac Ruzica , Soares Gustavo , Verbruggen Gust
Published: April 2024

Students often make mistakes in their introductory programming assignments as part of their learning process. Unfortunately, providing custom repairs for these mistakes can require a substantial amount of time and effort from class instructors. Automated program repair (APR) techniques can be used to synthesize such fixes. Prior work has explored the use of symbolic and neural techniques for APR in the education domain. Both types of approaches require either substantial engineering efforts or large amounts of data and training. We propose to use a large language model trained on code, such as Codex (a version of GPT), to build an APR system -- PyDex -- for introductory Python programming assignments. Our system can fix both syntactic and semantic mistakes by combining multi-modal prompts, iterative querying, test-case-based selection of few-shots, and program chunking. We evaluate PyDex on 286 real student programs and compare to three baselines, including one that combines a state-of-the-art Python syntax repair engine, BIFI, and a state-of-the-art Python semantic repair engine for student assignments, Refactory. We find that PyDex can fix more programs and produce smaller patches on average.
Seneca: Taint-Based Call Graph Construction for Java Object Deserialization
Authors: Santos Joanna C. S. , Mirakhorli Mehdi , Shokri Ali
Published: April 2024

Object serialization and deserialization are widely used for storing and preserving objects in files, memory, or database as well as for transporting them across machines, enabling remote interaction among processes and many more. This mechanism relies on reflection, a dynamic language that introduces serious challenges for static analyses. Current state-of-the-art call graph construction algorithms do not fully support object serialization/deserialization, i.e., they are unable to uncover the callback methods that are invoked when objects are serialized and deserialized. Since call graphs are a core data structure for multiple types of analysis (e.g., vulnerability detection), an appropriate analysis cannot be performed since the call graph does not capture hidden (vulnerable) paths that occur via callback methods. In this paper, we present Seneca, an approach for handling serialization with improved soundness in the context of call graph construction. Our approach relies on taint analysis and API modeling to construct sound call graphs. We evaluated our approach with respect to soundness, precision, performance, and usefulness in detecting untrusted object deserialization vulnerabilities. Our results show that Seneca can create sound call graphs with respect to serialization features. The resulting call graphs do not incur significant runtime overhead and were shown to be useful for performing identification of vulnerable paths caused by untrusted object deserialization.
Message-Observing Sessions
Authors: Kavanagh Ryan , Pientka Brigitte
Published: April 2024

We present Most, a process language with message-observing session types. Message-observing session types extend binary session types with type-level computation to specify communication protocols that vary based on messages observed on other channels. Hence, Most allows us to express global invariants about processes, rather than just local invariants, in a bottom-up, compositional way. We give Most a semantic foundation using traces with binding, a semantic approach for compositionally reasoning about traces in the presence of name generation. We use this semantics to prove type soundness and compositionality for Most processes. We see this as a significant step towards capturing message-dependencies and providing more precise guarantees about processes.
Iterative-Epoch Online Cycle Elimination for Context-Free Language Reachability
Authors: Xu Pei , Lei Yuxiang , Sui Yulei , Xue Jingling
Published: April 2024

Context-free language reachability (CFL-reachability) is a fundamental framework for implementing various static analyses. CFL-reachability utilizes context-free grammar (CFG) to extend the expressiveness of ordinary graph reachability from an unlabeled graph to an edge-labeled graph. Solving CFL-reachability requires a (sub)cubic time complexity with respect to the graph size, which limits its scalability in practice. Thus, an approach that can effectively reduce the graph size while maintaining the reachability result is highly desirable. Most of the existing graph simplification techniques for CFL-reachability work during the preprocessing stage, i.e., before the dynamic CFL-reachability solving process. However, in real-world CFL-reachability analyses, there is a large number of reducible nodes and edges that can only be discovered during dynamic solving, leaving significant room for on-the-fly improvements.

This paper aims to reduce the graph size of CFL-reachability dynamically via online cycle elimination. We propose a simple yet effective approach to detect collapsible cycles in the graph based on the input context-free grammar. Our key insight is that symbols with particular forms of production rules in the grammar are the essence of transitivity of reachability relations in the graph. Specifically, in the graph, a reachability relation to a node v_i can be "transited" to another node v_j if there is a transitive relation from v_i to v_j, and cycles formed by transitive relations are collapsible. In this paper, we present an approach to identify the transitive symbols in a context-free grammar and propose an iterative-epoch framework for online cycle elimination. From the perspective of non-parallelized CFL-reachability solving, our iterative-epoch framework is well compatible with both the standard (unordered) solver and the recent ordered solver, and can significantly improve their performance. Our experiment on context-sensitive value-flow analysis for C/C++ and field-sensitive alias analysis for Java demonstrates promising performance improvement by our iterative-epoch cycle elimination technique. By collapsing cycles online, our technique accelerates the standard solver by 17.17× and 13.94× for value-flow analysis and alias analysis, respectively, with memory reductions of 48.8% and 45.0%. Besides, our technique can also accelerate the ordered solver by 14.32× and 8.36× for value-flow analysis and alias analysis, respectively, with memory reductions of 55.2% and 57.8%.
Adaptive, Sociable and Ready for Anything: Undergraduate Students Are Resilient When Faced with Technological Change
Authors: Hossain Elahi , Cox Anna L. , Dowthwaite Anna , Rogers Yvonne
Published: April 2024

Attending university is an important time for many young people's social lives. But changes are afoot with new innovative digital higher-education experiences being built, shifting students' social lives further online. However, it is unclear how a longer-term shift to a digital university ecosystem will impact students and their social relations and how current technologies could amplify their social experience. We report a focus group study investigating the impact of a primarily digital university experience on the social relationships of incoming undergraduates. In line with existing research, we demonstrate how technology-mediated communications can benefit some aspects of students' social relations and less so for others. Our novel contribution is evidence of students' remarkable adaptiveness when facing an online-only university experience. Crucially, our participants identified and utilised the nuances of different online platforms to start and maintain new relationships. This way, they preserved their ability to nurture social relationships, even when dealing with an unexpected learning environment. We provide design recommendations for future metaversities and discuss students' resilience in sustaining personal relationships that can inform online-centric university models.
Computers as Bad Social Actors: Dark Patterns and Anti-Patterns in Interfaces that Act Socially
Authors: Alberts Lize , Lyngs Ulrik , Van Kleek Max
Published: April 2024

Interfaces increasingly mimic human social behaviours. Beyond prototypical examples like chatbots, basic automated systems like app notifications or self-checkout machines likewise address or 'talk to' people in person-like ways. Whilst early evidence suggests social cues can enhance user experience, we lack a good understanding of when, and why, their use in interaction design may be inappropriate. We combined a qualitative survey (n=80) with experience sampling, interview, and workshop studies (n=11) to understand people's attitudes and preferences regarding how a range of automated systems talk to/at them. We thematically analysed examples of phrasings or conduct our participants disliked, their reasons, and how they would prefer to be treated instead. One category of inappropriate use we identified is when social design elements are used to manipulate user behaviour. We distinguish four such tactics: 'agents' playing on users' emotions (e.g., guilt-tripping, coaxing), being pushy, mothering users, or being passive-aggressive. Another category regards pragmatics: personal or situational factors that can make even a seemingly helpful or friendly message come across as rude, tactless, invasive, etc. These include contextual insensitivity (e.g., embarrassing users in public); expressing clearly false personalised care; or treating a user in ways they find misaligned with the system's role or the nature of their relationship. We discuss these inappropriate uses in terms of an emerging 'social' class of dark and anti-patterns. From participant suggestions, we offer recommendations for improving how interfaces treat people in interaction, including broader normative reflections on treating users respectfully.
Material Mediation in Collaborative Activity
Authors: Bødker Susanne , Hoggan Eve , Larsen-Ledet Ida
Published: April 2024

The material qualities of technological mediators are vital to collaborative activity, but current paradigms for collaboration support leave the potential of material mediation largely untapped. The HCI literature addresses both material mediation for individuals and coordination between collaborators - but rarely does it discuss the more direct role of the material as standing between people: its communicative role. This paper unfolds a material/linguistic analysis of four empirical examples from previous work on collaborative writing to showcase how material qualities of both tools and the text-in-progress, used in both planned and improvised manners, help co-authors shift between levels of collaboration, from independent co-ordinated activity to highly collaborative co-constructive activity. On one hand, we see co-authors successfully collaborating through material means; on the other, we see frustrations resulting from limited material expressivity in current tools. This duality between the significance of material mediation and obstacles to drawing on its potential makes clear that our conception of materiality needs elaboration. We point to multimodality as one opportunity for this.
Design Tensions in Online Freelancing Platforms: Using Speculative Participatory Design to Support Freelancers' Relationships with Clients
Authors: Huang Jessica , Ma Ning F. , Rivera Veronica A. , Somani Tabreek , Lee Patrick Yung Kang , Mcgrenere Joanna , Yoon Dongwook
Published: April 2024

This paper explores the design challenges that arise in supporting online freelancers to navigate relationships with clients. Prior studies have shown that current platform designs can lead to worker precarity in freelancer-client relationships, such as power imbalances, information asymmetry, and labor abuse. To envision alternative designs that empower workers in managing their relationships with clients, we engaged 22 Upwork freelancers in participatory speculative design activities. Through this co-design process, we identified design tensions that constrain design options as a result of conflicting values and priorities that could only be balanced and compromised rather than completely resolved. Six design tensions were identified in the context of designing for four different phases of freelancing. We observed three patterns in these tensions: 1) the freelancers' need for client involvement in their tasks and career growth, which conflicted with their skepticism that clients had sufficient incentives to be involved; 2) that there was often no viable balancing option for some tensions, but they could be addressed through changes in the platform's incentive structure; and 3) some tensions occurred not only between freelancers and clients, but also within the freelancer community. We present three approaches for addressing these design tensions and discuss how this research can support more equitable and healthy freelancer-client relationships.
AI-Powered Reminders for Collaborative Tasks: Experiences and Futures
Authors: Morrison Katelyn , Iqbal Shamsi T. , Horvitz Eric
Published: April 2024

Email continues to serve as a central medium for managing collaborations. While unstructured email messaging is lightweight and conducive to coordination, it is easy to overlook commitments and requests for collaborations that are embedded in the text of free-flowing communications. Twenty-one years ago, Bellotti et al. proposed TaskMaster with the goal of redesigning the email interface to have explicit task management capabilities. Recently, AI-based task recognition and reminder services have been introduced in major email systems as one approach to managing asynchronous collaborations. While these services have been provided to millions of people around the world, there is little understanding of how people interact with and benefit from them. We explore knowledge workers' experiences with Microsoft's Viva Daily Briefing Email to better understand how AI-powered reminders can support asynchronous collaborations. Through semi-structured interviews and surveys, we shed light on how AI-powered reminders are incorporated into workflows to support asynchronous collaborations. We identify what knowledge workers prefer AI-powered reminders to remind them about and how they would like to interact with these reminders. Using mixed methods and a self-assessment methodology, we investigate the relationship between information workers' work styles and the perceived value of the Viva Daily Briefing Email to identify users who are more likely to benefit from AI-powered reminders for asynchronous collaborations. We conclude by discussing the experiences and futures of AI-powered reminders for collaborative tasks and asynchronous collaborations.
"Pinocchio had a Nose, You have a Network!": On Characterizing Fake News Spreaders on Arabic Social Media
Authors: Fawzi Mahmoud , Magdy Walid
Published: April 2024

The detection and analysis of fake news and its origins has become a main task associated with the overall objective of social media regulation in recent years. The majority of work has been dedicated towards detecting misinformation with some focus on analyzing the flow of fake news across social networks. However, there is less attention to the characteristics of social media users who consume this fake news. In this work, we investigate the possibility of predicting users' reactions towards fake news and defining some network characteristics for each users' group. We utilized a set of fact-checking websites in the Arab world that report social media posts spreading fake news and the interactions with them. We defined three sets of users: 1) Spreaders, who spread fake news, 2) Checkers, who constantly share fact-checking threads, and 3) Refuters, who respond to fake-news posts declaring their inaccuracy. We build a classifier that uses users' network graph to predict their reactions with an accuracy exceeding 93%. We applied further analysis for the most significant features of each users group and noticed that spreaders interact with more accounts that use their mother tongue, a considerable number of famous state-sponsored accounts, and accounts that get suspended while checkers and refuters interact with more foreign accounts and news-reporting entities. Central nodes in the networks of spreaders were found to be linked with state-sponsored media, whereas central nodes in the networks of checkers included organizations with a cross-cultural nature.
It's About the Journey - Capturing Stories of the Fluctuating Experiences of Youth Kidney Transplant Patients
Authors: Dunbar Julia C. , Pratt Wanda , Bascom Emily , Currier Cara , Garcia Joseph William Tan , Smith Jodi , Snyder Jaime , Pollack Ari H
Published: April 2024

Youth who undergo a kidney transplant can experience a fluctuation of successes and challenges throughout their chronic illness journey. Designing to capture their journey could help youth to reflect on their experiences, collaborate on their care, and be empowered to live their lives to the fullest. We interviewed 11 youth kidney transplant patients and 12 caregivers to elicit their transplant journey experiences. We found that probing participants about specific parts of their transplant journey gave them structure to tell us rich stories about their experiences. Based on our findings, we discuss informing the design of a tool to support the capturing of stories for youth with chronic illnesses. Designing such tool could help youth and their caregivers to identify barriers, support reflection, and promote self-efficacy. Youth with chronic illnesses already have to change so many aspects of their lives to accommodate their illness, however, by giving them a platform to capture their chronic illness journey, it could encourage them to take more control of their lives and better collaborate with others.
"I will just have to keep driving": A Mixed-methods Investigation of Lack of Agency within the Thai Motorcycle Rideshare Driver Community
Authors: Tieanklin Nussara , Breda Joseph , Althoff Tim , Heimerl Kurtis
Published: April 2024

This paper presents a mixed-methods study of app-based motorcycle taxis in Thailand to explore the social dynamics of rideshare drivers and their exercised autonomy both through social pressure and a hostile work environment. As motorcycle taxis are open-air vehicles, drivers can be exposed to prolonged air pollution and other weather events, potentially impacting their health. In an initial quantitative study of server-side rideshare logs, we unexpectedly found that drivers do not exercise the autonomy provided by their rideshare platform to avoid air pollution events. This prompted a follow-on investigation through semi-structured interviews of both drivers and passengers in three provinces to explore why these drivers fail to experience the autonomy promised by gig-work in this context and elucidated further examples this lack of autonomy experienced by drivers. Our study sheds light on the social context that may constrain a driver's agency, including financial pressures, weather conditions, conflicts with local taxi organizations, and a false perception that drivers need to work around the ride assignment algorithm to avoid being blacklisted. We find that when leveraging app-based rideshare opportunities, drivers simultaneously perceive increased flexibility in their work hours and a lack of agency to prioritize their health and safety. We conclude with a discussion on potential interventions aimed at mitigating the forces preventing drivers from exercising their autonomy.
Adopting Third-party Bots for Managing Online Communities
Authors: Hwang Sohyeon , Kiene Charles , Ong Serene , Shaw Aaron
Published: April 2024

Bots have become critical for managing online communities on platforms, especially to match the increasing technical sophistication of online harms. However, community leaders often adoptthird-party bots, creating room for misalignment in their assumptions, expectations, and understandings (i.e., their technological frames) about them. On platforms where sharing bots can be extremely valuable, how community leaders can revise their frames about bots to more effectively adopt them is unclear. In this work, we conducted a qualitative interview study with 16 community leaders on Discord examining how they adopt third-party bots. We found that participants addressed challenges stemming from uncertainties about a bot's security, reliability, and fit through emergent social ecosystems. Formal and informal opportunities to discuss bots with others across communities enabled participants to revise their technological frames over time, closing gaps in bot-specific skills and knowledge. This social process of learning shifted participants' perspectives of the labor of bot adoption into something that was satisfying and fun, underscoring the value of collaborative and communal approaches to adopting bots. Finally, by shaping participants' mental models of the nature, value, and use of bots, social ecosystems also raise some practical tensions in how they support user creativity and customization in third-party bot use. Together, the social nature of adopting third-party bots in our interviews offers insight into how we can better support the sharing of valuable user-facing tools across online communities.
A Survey of Multimodal Perception Methods for Human–Robot Interaction in Social Environments
Authors: Duncan John A. , Alambeigi Farshid , Pryor Mitchell W.
Published: April 2024

Human–robot interaction (HRI) in human social environments (HSEs) poses unique challenges for robot perception systems, which must combine asynchronous, heterogeneous data streams in real time. Multimodal perception systems are well-suited for HRI in HSEs and can provide more rich, robust interaction for robots operating among humans. In this article, we provide an overview of multimodal perception systems being used in HSEs, which is intended to be an introduction to the topic and summary of relevant trends, techniques, resources, challenges, and terminology. We surveyed 15 peer-reviewed robotics and HRI publications over the past 10+ years, providing details about the data acquisition, processing, and fusion techniques used in 65 multimodal perception systems across various HRI domains. Our survey provides information about hardware, software, datasets, and methods currently available for HRI perception research, as well as how these perception systems are being applied in HSEs. Based on the survey, we summarize trends, challenges, and limitations of multimodal human perception systems for robots, then identify resources for researchers and developers and propose future research areas to advance the field.
A Review on the Impact of Data Representation on Model Explainability
Authors: Haghir Chehreghani Mostafa
Published: April 2024

In recent years, advanced machine learning and artificial intelligence techniques have gained popularity due to their ability to solve problems across various domains with high performance and quality. However, these techniques are often so complex that they fail to provide simple and understandable explanations for the outputs they generate. To address this issue, the field of
explainable artificial intelligence
has recently emerged. However, most data generated in different domains are inherently structural; that is, they consist of parts and relationships among them. Such data can be represented using either a simple
data-structure
or
form
, such as a
vector
, or a complex data-structure, such as a
graph
. The effect of this representation form on the explainability and interpretability of machine learning models is not extensively discussed in the literature. In this survey article, we review efficient algorithms proposed for learning from inherently structured data, emphasizing how their representation form affects the explainability of learning models. A conclusion of our literature review is that using complex
forms
or
data-structures
for data representation improves not only the learning performance but also the explainability and transparency of the model.
Grid Cells in Cognition: Mechanisms and Function
Authors: Dong Ling L. , Fiete Ila R.
Published: April 2024

The activity patterns of grid cells form distinctively regular triangular lattices over the explored spatial environment and are largely invariant to visual stimuli, animal movement, and environment geometry. These neurons present numerous fascinating challenges to the curious (neuro)scientist: What are the circuit mechanisms responsible for creating spatially periodic activity patterns from the monotonic input-output responses of single neurons? How and why does the brain encode a local, nonperiodic variable—the allocentric position of the animal—with a periodic, nonlocal code? And, are grid cells truly specialized for spatial computations? Otherwise, what is their role in general cognition more broadly? We review efforts in uncovering the mechanisms and functional properties of grid cells, highlighting recent progress in the experimental validation of mechanistic grid cell models, and discuss the coding properties and functional advantages of the grid code as suggested by continuous attractor network models of grid cells.
Groundwater Institutions in the Face of Global Climate Change
Authors: Zhao Jinhua , Hendricks Nathan P. , Li Haoyang
Published: April 2024

We review the literature on the performance of groundwater institutions, including command-and-control (CAC) approaches, market-based institutions (MBIs), and voluntary approaches, and evaluate how they will perform as agriculture adapts to climate change. Both CAC approaches and MBIs lead to uneven distributional impacts on farmers, and voluntary approaches have not been successful in reducing water withdrawal on a large scale. A polycentric approach of regulation plus local management might perform well. Climate change will increase the irrigation demand for groundwater and demand flexible and properly scoped institutions that attend to local conditions.
A Highly Synergistic Dual-Cathode Electro-Fenton Process with Self-Regulation of pH and Coating Stability for the Effective Degradation of Refractory Pollutants
Authors: Zhao Jieyu , Zhang Jiye , An Zhijia , Liang Yajie , Zhao Yisong , Pei Pei , Wang Lin , Gao Weiqi , Jin Li
Published: April 2024

As a result of issues related to pH control and the competition between H2O2 production and activation at the same sites, the applications of electro-Fenton (EF) pollutant remediation systems are limited. This work designed a synergistic dual-cathode EF system that exhibits self-adjustment of pH and stable electrode coatings. This system is based on using biomass as the active cathode material for H2O2 generation and the interaction between a stainless-steel mesh and FeOCl to reduce Fe3+ ions. The synergistic factor for this dual-cathode system was calculated to be 85.2%. Significantly, the production and activation of H2O2 in this composite system are unaffected by pH and the pH value can be adjusted between 9.67 and 3.7 without adding any acidic reagents. This process allows for the degradation of recalcitrant organic pollutants over the pH range of 3 to 9 without pre-acidification or challenges related to iron sludge and effluent chromaticity. Various organic pollutants, including antibiotics and organic dyes, can be effectively decomposed using this technology, which also exhibits good stability throughout 22 continuous trials over 1400 min. This work demonstrates a novel yet viable approach to highly efficient, inexpensive pollutant treatment with good reusability, a wide pH range and no iron leaching.
Optimizing Wireless Sensor Networks through Ant Colony-Based Localized Mesh Topology
Authors: Gupta Shilpa , Chopra Amit , Bala Madhu , Sharma Ritika
Published: April 2024

The growing need for faster and more effective data handling and data transfer capabilities of a network require energy-efficient and more powerful smart sensor devices. These devices have become increasingly necessary in wireless sensor networks (WSN). The architecture or topology of WSN can greatly impact the organizational efficacy and connectivity among the sensor nodes employed within the given area. It is foremost important to implement a robust network topology which must be capable of ensuring continuous and reliable communication within the whole network. This research paper presents an effective approach based on Ant colony scheme to optimize mesh network topology ant colony optimization (ACO) is used to place the sensor nodes optimally in the given area of the whole network. The proposed research carries out comprehensive performance evaluation of the network under various QoS parameters such as bandwidth, throughput, delay, residual energy and routing load. These parameters shows the effectiveness or adaptability of the network with different and dynamically changing communication requirements suggested by this topology scheme. The network based on the proposed method has been simulated several times and the achieved simulation patterns have been analyzed under the mentioned QoS constraints.
Impact of CeCo-Coated Metallic Interconnectors on SOCs Towards Performance, Cr-Oxide-Scale, and Cr-Evaporation
Authors: Grosselindemann C. , Reddy M. J. , Störmer H. , Esau D. , Dorn M. , Bauer F. M. , Ewald D. , Wissmeier L. , Froitzheim J. , Weber A.
Published: April 2024

The performance of a solid oxide cell (SOC) depends on the operating environment. Regarding single cell tests with ideal contacting (gold, platinum, nickel meshes) and inert flow fields (Al2O3), performance is limited by intrinsic losses in the cell. Contact losses and poisoning effects are minimized. In a SOC-stack with metallic interconnectors, performance is affected by contact resistances, chromium (Cr) evaporation, and limitations in gas supply. Here, 1 cm2 single cells were tested with a stack-like contact applying metallic flow fields made from three different steel grades (Crofer 22 APU, AISI 441, UNS S44330) with and without a cerium-cobalt PVD-coating. Cell performance and losses were analyzed by IV-characteristics, impedance spectroscopy, and DRT analysis. For all uncoated interconnectors, significant performance losses due to increased contact losses and air electrode polarization were observed, which is attributed to Cr-oxide scale formation on the metallic interconnectors and Cr-poisoning of the air electrode as revealed by scanning electron microscopy-energy-dispersive X-ray spectroscopy. A CeCo-coating leads to similar oxide scales irrespective of the substrate material. Moreover, with the coating the electrochemical performance drastically improved due to decreased contact losses and an effective blocking of Cr-evaporation leading to a cell performance close to the ideal case for all three steel grades.
Gas Transport Resistance of Hydrocarbon-Based Catalyst Layers in Proton-Exchange Membrane Fuel Cells
Authors: Liepold Hannes , Nguyen Hien , Heizmann Philipp A. , Klose Carolin , Vierrath Severin , Münchinger Andreas
Published: April 2024

Recent developments in hydrocarbon-based proton exchange membrane fuel cells have significantly narrowed the performance gap compared to state-of-the-art cells using perfluorosulfonic acid ionomers (PFSA). However, balancing protonic resistance and gas transport resistance in the catalyst layer remains a challenge at low humidity. This study investigates gas transport resistance and its components in sulfonated phenylated polyphenylene-based catalyst layers using various limiting current methods. Results show that increasing the dry ionomer to carbon (I/C) ratio from 0.2 to 0.4, a measure to catch up with protonic resistance of PFSA-based catalyst layers, significantly increases gas transport resistance in the cathode catalyst layer by 28 %. The data suggest a strong correlation between local gas transport resistance and IEC. A high IEC is beneficial for the gas transport through the ionomer film. However, at low ionomer volume fractions the local gas transport resistance is dominated by the I/C independent interfacial resistance. Furthermore, a low IEC hydrocarbon ionomer, such as Pemion® PP1-HNN4–00-X (IEC = 2.5 meq g−1), not only exhibits a beneficial interfacial resistance, but also suppresses excessive ionomer swelling, which typically occurs during operating conditions where liquid water is forming.
Review—Reference Electrodes in Proton Exchange Membrane Water Electrolysis: Previous Approaches, Current Application, and Perspectives
Authors: Bühre Lena V. , Bensmann Boris , Hanke-Rauschenbach Richard
Published: April 2024

The commercialization of proton exchange membrane water electrolysis cells (PEMWEs), which are essential for a greener and more sustainable future, is hindered by the high costs of noble metal catalysts, as well as the degradation of the catalysts and membranes. Examining the electrodes’ characteristics with reference electrodes (REs) yields insights into their individual performance and can, e.g., help assess new catalyst layer designs, their interplay with the adjacent porous transport layer, or understand the complex and multi-faceted degradation mechanisms. This review provides an overview of previous approaches and the evolution of RE designs in PEMWE. By discussing the strengths and limitations of different RE setups, readers are enabled to make more informed decisions about their experiments’ design and choose the best RE setup for their specific research question.
Electrodeposition of Cu with Amino Acids toward Electrocatalytic Enhancement of CO2 Reduction Reaction
Authors: Tsuda Yuki , Yoshii Kazuki , Gunji Takao , Takeda Sahori , Takeichi Nobuhiko
Published: April 2024

This study investigates the effect of five amino acids on the electrodeposition of Cu to enhance its electrocatalytic performance in CO2 reduction reactions (CO2RR). The amino acids significantly influenced the deposition potential, crystallite size, and surface morphology of the electrodeposited Cu. Electrodeposited Cu with amino acids exhibit significantly smaller crystallites and higher particle density on carbon paper relative to amino acid-free samples. The integration of amino acids into the electrodeposited Cu was confirmed via high-angle annular dark-field scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and hard X-ray photoelectron spectroscopy. All electrodeposited Cu exhibits a higher faradaic efficiency (FE) in the electrochemical reduction of CO2 to CH4 relative to Cu foil (24.2%), regardless of the presence or absence (55.0%) of amino acids when the electrolysis was conducted at −1.27 V vs RHE. Electrodeposited Cu with L-histidine, containing an imidazole group, demonstrates a higher FE of CH4 (67.6%) and effectively suppressed the hydrogen evolution reaction, highlighting the crucial role of amino acid functional groups, particularly imidazole, in augmenting the electrochemical conversion of CO2 to CH4. The study demonstrates the critical influence of specific functional groups in amino acids on the catalytic efficiency of electrodeposited Cu in CO2RR electrocatalysis applications.
Pioglitazone does not enhance exogenous glucose oxidation or metabolic clearance rate during aerobic exercise in men under acute high-altitude exposure
Authors: Margolis Lee M. , Wilson Marques A. , Drummer Devin J. , Carrigan Christopher T. , Murphy Nancy E. , Allen Jillian T. , Dawson M. Alan , Mantzoros Christos S. , Young Andrew J. , Pasiakos Stefan M.
Published: April 2024

Short-term (5 days) use of the oral insulin sensitizer pioglitazone does not alter circulating glucose or insulin responses to enhance exogenous glucose oxidation during steady-state aerobic exercise in young healthy men under simulated acute (8 h) high-altitude (460 mmHg) conditions. These results indicate that dysregulations in glucose metabolism in native lowlanders sojourning at high altitude may not be due to insulin resistance at peripheral tissue.
Creep Energy Evolution of Red-Bed Soft Rocks in South China under Chemical-Stress-Seepage Coupling
Authors: Zhang Shuguang , Peng Fanyao , Li Yingbo , Liu Zhifeng , Liu Wenbo
Published: April 2024

The red-bed soft rocks in South China have obvious creep characteristics and are prone to engineering geological disasters such as landslide and foundation settlement under the action of rainfall, groundwater, and load. In order to reveal its creep characteristics and mechanism under complex conditions, a step-loading creep test was carried out under chemical-stress-seepage coupling, and the energy evolution law of the whole creep process was analyzed based on linear energy storage and energy dissipation theory. The results also show that the acid chemical solution has the greatest influence on the triaxial strength and creep strength, and the creep damage and energy evolution of red-bed soft rock are universal. The creep damage and total strain increase with the increase of acidity, the decrease of confining pressure, and the increase of seepage pressure. The evolution law of creep damage shows the characteristics of slow-acceleration-rapid growth, and with the increase of load level, it has obvious transfer and accumulation. After entering the constant velocity creep stage, the damage rate begins to accelerate. The proportion of instantaneous strain and creep strain in the total strain increment is about 50%, and confining pressure has little influence on their respective proportions. The instantaneous strain is more sensitive to the acidity of the chemical solution, and the proportion of creep strain increases gradually with the increase of seepage pressure. The relationship between elastic energy density and total energy density is linear. The elastic energy density and dissipated energy density in the loading stage and creep stage all increase nonlinearly with loading time. The density of dissipated energy in the creep phase is lower than that in the loading phase, but the opposite is true in the higher stress phase, and the law of energy dissipation can explain the hardening damage effect in the creep process of soft rock samples. The research results provide a new perspective for us to reveal the mechanical properties and failure mechanism of red-bed soft rocks and provide an important theoretical basis for predicting and evaluating the creep instability and long-term stability of such rocks.
Community Engagement in Health Promotion: Results from a Realist Multiple Case Study
Authors: Hogeling Lette , Koelen Maria , Vaandrager Lenneke
Published: April 2024

Community engagement (CE) has long been endorsed by policy makers and health practitioners. However, uncertainties remain about the workings and outcomes of CE. This study aims to provide in‐depth insights into them. In a multiple case study, we investigated three participatory health promotion projects for families in vulnerable situations in the Netherlands. We adopted a realist approach combined with a theory of change (ToC) model. We then analysed the qualitative data for context–mechanism–outcome (CMO) configurations to refine this ToC. Results show that CE can strengthen social networks, empower families, and increase perceived health. However, specific contexts in combination with CE project approaches may or may not trigger positive responses. Participants may feel that they matter when asked to actively contribute to a project, which in turn can enhance their self‐confidence. In another context, we found that families were overwhelmed by the responsibilities given to them in the project, leading to feelings of stress and withdrawal from the project. We present a list of CMO configurations and refine the ToC accordingly. Our main conclusion is that flexibility is key when CE is implemented in health promotion. Also, our findings question physical health outcomes as a realistic ambition for CE projects with groups in vulnerable situations.
Black Carp Mylopharyngodon piceus (Richardson, 1846) Mouth Gape and Size Preference of a Bivalve Prey
Authors: Kroboth Patrick T. , Stahlschmidt Benjamin H. , Chapman Duane C.
Published: April 2024

Black carp Mylopharyngodon piceus (Richardson, 1846) have been widely used as biological control of snails in aquaculture and were imported to the United States in the 1970s and 1980s for this purpose. Prior research emphasizes the species’ propensity to control gastropods, but since subsequent escape and establishment of black carp in portions of the Mississippi River Basin, concerns now focus on the numerous endangered and endemic bivalve species upon which black carp may predate. Black carp mouth gape may limit predation on larger bivalves, but bite force is also a factor. We used regression of fish length to mouth gape of wild-caught black carp and compared these results to tank forage size preference trials with bivalve prey Corbicula fluminea clams. Wild-caught black carp ranged from 429 to 1580 mm total length, a size range larger than measured in previous studies. Regression of fish length and mouth gape indicated greater variability among sizes, as expected from wild versus cultured populations. Clam consumption was size-dependent. Black carp commonly engulfed but did not consume the largest clams in tank feeding trials. Shell width was a better predictor of successful consumption than length or height. Predation was restricted at sizes less than the mouth gape of test black carp as observed by individuals engulfing but failing to consume prey. This result indicates that either bite force or the pharyngeal apparatus gape (i.e., the distance between the pharyngeal teeth and keratinous pad) limited successful crushing of engulfed shells. Bivalve predation by black carp is limited by both a fish’s ability to engulf prey and the ability to fracture the shell of larger prey items that cannot be broken or swallowed whole. The results of this research may be used to assess potential prey sizes of wild black carp and anticipated effects of predation on bivalve communities.