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Numrering	Referens	Omslagsbild	Hitta
1.	Ahmad, Iftikhar, et al. (författare) Using algorithmic trading to analyze short term profitability of Bitcoin 2021 Ingår i: PeerJ Computer Science. - : PeerJ Publishing. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract Cryptocurrencies such as Bitcoin (BTC) have seen a surge in value in the recent past and appeared as a useful investment opportunity for traders. However, their short term profitability using algorithmic trading strategies remains unanswered. In this work, we focus on the short term profitability of BTC against the euro and the yen for an eight-year period using seven trading algorithms over trading periods of length 15 and 30 days. We use the classical buy and hold (BH) as a benchmark strategy. Rather surprisingly, we found that on average, the yen is more profitable than BTC and the euro; however the answer also depends on the choice of algorithm. Reservation price algorithms result in 7.5% and 10% of average returns over 15 and 30 days respectively which is the highest for all the algorithms for the three assets. For BTC, all algorithms outperform the BH strategy. We also analyze the effect of transaction fee on the profitability of algorithms for BTC and observe that for trading period of length 15 no trading strategy is profitable for BTC. For trading period of length 30, only two strategies are profitable.
2.	Capuccini, Marco, et al. (författare) On-demand virtual research environments using microservices 2019 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 5 Tidskriftsartikel (refereegranskat)abstract The computational demands for scientific applications are continuously increasing. The emergence of cloud computing has enabled on-demand resource allocation. However, relying solely on infrastructure as a service does not achieve the degree of flexibility required by the scientific community. Here we present a microservice-oriented methodology, where scientific applications run in a distributed orchestration platform as software containers, referred to as on-demand, virtual research environments. The methodology is vendor agnostic and we provide an open source implementation that supports the major cloud providers, offering scalable management of scientific pipelines. We demonstrate applicability and scalability of our methodology in life science applications, but the methodology is general and can be applied to other scientific domains.
3.	Carbonell, Marcos Fernandez, et al. (författare) Comparing supervised and unsupervised approaches to multimodal emotion recognition 2021 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract We investigated emotion classification from brief video recordings from the GEMEP database wherein actors portrayed 18 emotions. Vocal features consisted of acoustic parameters related to frequency, intensity, spectral distribution, and durations. Facial features consisted of facial action units. We first performed a series of person-independent supervised classification experiments. Best performance (AUC = 0.88) was obtained by merging the output from the best unimodal vocal (Elastic Net, AUC = 0.82) and facial (Random Forest, AUC = 0.80) classifiers using a late fusion approach and the product rule method. All 18 emotions were recognized with above-chance recall, although recognition rates varied widely across emotions (e.g., high for amusement, anger, and disgust; and low for shame). Multimodal feature patterns for each emotion are described in terms of the vocal and facial features that contributed most to classifier performance. Next, a series of exploratory unsupervised classification experiments were performed to gain more insight into how emotion expressions are organized. Solutions from traditional clustering techniques were interpreted using decision trees in order to explore which features underlie clustering. Another approach utilized various dimensionality reduction techniques paired with inspection of data visualizations. Unsupervised methods did not cluster stimuli in terms of emotion categories, but several explanatory patterns were observed. Some could be interpreted in terms of valence and arousal, but actor and gender specific aspects also contributed to clustering. Identifying explanatory patterns holds great potential as a meta-heuristic when unsupervised methods are used in complex classification tasks.
4.	Carvalho, Joao Frederico, 1988-, et al. (författare) An algorithm for calculating top-dimensional bounding chains 2018 Ingår i: PEERJ COMPUTER SCIENCE. - : PEERJ INC. - 2376-5992. Tidskriftsartikel (refereegranskat)abstract We describe the Coefficient-Flow algorithm for calculating the bounding chain of an (n-1)-boundary on an n-manifold-like simplicial complex S. We prove its correctness and show that it has a computational time complexity of O(vertical bar S(n-1)vertical bar) (where S(n-1) is the set of (n-1)-faces of S). We estimate the big-O coefficient which depends on the dimension of S and the implementation. We present an implementation, experimentally evaluate the complexity of our algorithm, and compare its performance with that of solving the underlying linear system.
5.	Chae, Han, et al. (författare) Cloninger’s TCI associations with adaptive and maladaptive emotion regulation strategies 2019 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 7 Tidskriftsartikel (refereegranskat)abstract Background. Cognitive emotion regulation plays a crucial role in psychopathology, resilience and well-being by regulating response to stress situations. However, the relationship between personality and adaptive and maladaptive regulation has not been sufficiently examined. Methods. Adaptive and maladaptive cognitive emotion regulation strategies of 247 university students were measured using the Cognitive Emotion Regulation Questionnaire (CERQ) and their temperament and character characteristics were analyzed with the Temperament and Character Inventory – Revised Short (TCI-RS). Two-step hierarchical multiple regression analyses were used to analyze whether TCI-RS explains the use of adaptive and maladaptive cognitive emotion regulation strategies. The latent classes of cognitive emotion regulation strategies were extracted with Latent Class Analysis (LCA) and significant differences in the subscales of CERQ and TCI-RS were examined with Analysis of Covariance (ANCOVA) and Profile Analysis after controlling for sex and age. Results. The two-step hierarchical multiple regression model using the seven TCI-RS subscales explained 32.30% of the adaptive and 41.70% of the maladaptive CERQ subscale scores when sex and age were introduced in the first step as covariates. As for temperament, Novelty Seeking (NS) and Persistence (PS) were pivotal for adaptive and Harm Avoidance (HA) and PS for maladaptive CERQ total scores. In addition, the character traits Self-Directedness (SD) and Cooperativeness (CO) were critical for high adaptive and low maladaptive CERQ scores. Four latent emotion regulation classes were confirmed through LCA, and distinct TCI-RS profiles were found. The temperament trait HA and character trait SD were significantly different among the four latent emotion regulation classes. Discussion. This study demonstrated that SD and CO are related to cognitive emotion regulation strategies along with psychological health and well-being, and that PS exhibits dualistic effects when combined with NS or HA on response to stressful situations. The importance of developing mature character represented by higher SD and CO in regard to mental health and its clinical implementation was discussed.
6.	Dobslaw, Felix, 1983-, et al. (författare) Automated black-box boundary value detection 2023 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 9 Tidskriftsartikel (refereegranskat)abstract Abstract Software systems typically have an input domain that can be subdivided into sub-domains, each of which generates similar or related outputs. Testing it on the boundaries between these sub-domains is critical to ensure high-quality software. Therefore, boundary value analysis and testing have been a fundamental part of the software testing toolbox for a long time and are typically taught early to software engineering students. Despite its many argued benefits, boundary value analysis for a given software specification or application is typically described in abstract terms. This allows for variation in how testers apply it and in the benefits they see. Additionally, its adoption has been limited since it requires a specification or model to be analysed. We propose an automated black-box boundary value detection method to support software testers in performing systematic boundary value analysis. This dynamic method can be utilized even without a specification or model. The proposed method is based on a metric referred to as the program derivative, which quantifies the level of boundariness of test inputs. By combining this metric with search algorithms, we can identify and rank pairs of inputs as good boundary candidates, i.e., inputs that are in close proximity to each other but with outputs that are far apart. We have implemented the AutoBVA approach and evaluated it on a curated dataset of example programs. Furthermore, we have applied the approach broadly to a sample of 613 functions from the base library of the Julia programming language. The approach could identify boundary candidates that highlight diverse boundary behaviours in over 70% of investigated systems under test. The results demonstrate that even a simple variant of the program derivative, combined with broad sampling and search over the input space, can identify interesting boundary candidates for a significant portion of the functions under investigation. In conclusion, we also discuss the future extension of the approach to encompass more complex systems under test cases and datatypes.
7.	Dobslaw, Felix, et al. (författare) Automated black-box boundary value detection 2023 Ingår i: PeerJ Computer Science. - 2376-5992. ; 9 Tidskriftsartikel (refereegranskat)abstract Software systems typically have an input domain that can be subdivided into subdomains, each of which generates similar or related outputs. Testing it on the boundaries between these sub-domains is critical to ensure high-quality software. Therefore, boundary value analysis and testing have been a fundamental part of the software testing toolbox for a long time and are typically taught early to software engineering students. Despite its many argued benefits, boundary value analysis for a given software specification or application is typically described in abstract terms. This allows for variation in how testers apply it and in the benefits they see. Additionally, its adoption has been limited since it requires a specification or model to be analysed. We propose an automated black-box boundary value detection method to support software testers in performing systematic boundary value analysis. This dynamic method can be utilized even without a specification or model. The proposed method is based on a metric referred to as the program derivative, which quantifies the level of boundariness of test inputs. By combining this metric with search algorithms, we can identify and rank pairs of inputs as good boundary candidates, i.e., inputs that are in close proximity to each other but with outputs that are far apart. We have implemented the AutoBVA approach and evaluated it on a curated dataset of example programs. Furthermore, we have applied the approach broadly to a sample of 613 functions from the base library of the Julia programming language. The approach could identify boundary candidates that highlight diverse boundary behaviours in over 70% of investigated systems under test. The results demonstrate that even a simple variant of the program derivative, combined with broad sampling and search over the input space, can identify interesting boundary candidates for a significant portion of the functions under investigation. In conclusion, we also discuss the future extension of the approach to encompass more complex systems under test cases and datatypes.
8.	Dobslaw, Felix, et al. (författare) Automated black-box boundary value detection 2023 Ingår i: PeerJ Computer Science. - 2376-5992. ; 9 Tidskriftsartikel (refereegranskat)abstract Software systems typically have an input domain that can be subdivided into subdomains, each of which generates similar or related outputs. Testing it on the boundaries between these sub-domains is critical to ensure high-quality software. Therefore, boundary value analysis and testing have been a fundamental part of the software testing toolbox for a long time and are typically taught early to software engineering students. Despite its many argued benefits, boundary value analysis for a given software specification or application is typically described in abstract terms. This allows for variation in how testers apply it and in the benefits they see. Additionally, its adoption has been limited since it requires a specification or model to be analysed. We propose an automated black-box boundary value detection method to support software testers in performing systematic boundary value analysis. This dynamic method can be utilized even without a specification or model. The proposed method is based on a metric referred to as the program derivative, which quantifies the level of boundariness of test inputs. By combining this metric with search algorithms, we can identify and rank pairs of inputs as good boundary candidates, i.e., inputs that are in close proximity to each other but with outputs that are far apart. We have implemented the AutoBVA approach and evaluated it on a curated dataset of example programs. Furthermore, we have applied the approach broadly to a sample of 613 functions from the base library of the Julia programming language. The approach could identify boundary candidates that highlight diverse boundary behaviours in over 70% of investigated systems under test. The results demonstrate that even a simple variant of the program derivative, combined with broad sampling and search over the input space, can identify interesting boundary candidates for a significant portion of the functions under investigation. In conclusion, we also discuss the future extension of the approach to encompass more complex systems under test cases and datatypes.
9.	Erlenhov, Linda, 1979, et al. (författare) Dependency management bots in open-source systems—prevalence and adoption 2022 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 8 Tidskriftsartikel (refereegranskat)abstract Bots have become active contributors in maintaining open-source repositories. However, the definitions of bot activity in open-source software vary from a more lenient stance encompassing every non-human contributions vs frameworks that cover contributions from tools that have autonomy or human-like traits (i.e., Devbots). Understanding which of those definitions are being used is essential to enable (i) reliable sampling of bots and (ii) fair comparison of their practical impact in, e.g., developers’ productivity. This paper reports on an empirical study composed of both quantitative and qualitative analysis of bot activity. By analysing those two bot definitions in an existing dataset of bot commits, we see that only 10 out of 54 listed tools (mainly dependency management) comply with the characteristics of Devbots. Moreover, five of those Devbots have similar patterns of contributions over 93 projects, such as similar proportions of merged pull-requests and days until issues are closed. Our analysis also reveals that most projects (77%) experiment with more than one bot before deciding to adopt or switch between bots. In fact, a thematic analysis of developers’ comments in those projects reveal factors driving the discussions about Devbot adoption or removal, such as the impact of the generated noise and the needed adaptation in development practices within the project.
10.	Farshin, Alireza, 1992-, et al. (författare) Overcoming the IOTLB wall for multi-100-Gbps Linux-based networking 2023 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 9, s. e1385- Tidskriftsartikel (refereegranskat)abstract This article explores opportunities to mitigate the performance impact of IOMMU on high-speed network traffic, as used in the Linux kernel. We first characterize IOTLB behavior and its effects on recent Intel Xeon Scalable & AMD EPYC processors at 200 Gbps, by analyzing the impact of different factors contributing to IOTLB misses and causing throughput drop (up to 20% compared to the no-IOMMU case in our experiments). Secondly, we discuss and analyze possible mitigations, including proposals and evaluation of a practical hugepage-aware memory allocator for the network device drivers to employ hugepage IOTLB entries in the Linux kernel. Our evaluation shows that using hugepage-backed buffers can completely recover the throughput drop introduced by IOMMU. Moreover, we formulate a set of guidelines that enable network developers to tune their systems to avoid the “IOTLB wall”, i.e., the point where excessive IOTLB misses cause throughput drop. Our takeaways signify the importance of having a call to arms to rethink Linux-based I/O management at higher data rates.
11.	Fasi, Massimiliano, 1989-, et al. (författare) Numerical behavior of NVIDIA tensor cores 2021 Ingår i: PeerJ Computer Science. - : PeerJ, Inc. - 2376-5992. ; 7, s. 1-19 Tidskriftsartikel (refereegranskat)abstract We explore the floating-point arithmetic implemented in the NVIDIA tensor cores, which are hardware accelerators for mixed-precision matrix multiplication available on the Volta, Turing, and Ampere microarchitectures. Using Volta V100, Turing T4, and Ampere A100 graphics cards, we determine what precision is used for the intermediate results, whether subnormal numbers are supported, what rounding mode is used, in which order the operations underlying the matrix multiplication are performed, and whether partial sums are normalized. These aspects are not documented by NVIDIA, and we gain insight by running carefully designed numerical experiments on these hardware units. Knowing the answers to these questions is important if one wishes to: (1) accurately simulate NVIDIA tensor cores on conventional hardware; (2) understand the differences between results produced by code that utilizes tensor cores and code that uses only IEEE 754-compliant arithmetic operations; and (3) build custom hardware whose behavior matches that of NVIDIA tensor cores. As part of this work we provide a test suite that can be easily adapted to test newer versions of the NVIDIA tensor cores as well as similar accelerators from other vendors, as they become available. Moreover, we identify a non-monotonicity issue affecting floating point multi-operand adders if the intermediate results are not normalized after each step.
12.	Garcia, Danilo, 1973 (författare) How “Dirty” is the Dark Triad? Dark Character Profiles, Swearing, and Sociosexuality 2020 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 8, s. 1-18 Tidskriftsartikel (refereegranskat)abstract Malevolent character traits (i.e., the Dark Triad: Machiavellianism, narcissism, and psychopathy) are associated to emotional frigidity, antagonism, immoral strategic thinking, betrayal, exploitation, and sexual promiscuity. Despite the fact that character is a complex adaptive system, almost every study has solely investigated the linear association between malevolent character and attitudes towards both swearing and sociosexual orientation (i.e., behavior, attitude, and desire regarding promiscuous sexual behavior). In contrast, the aim in this set of studies was to evaluate these associations in relation to specific profiles of malevolent character (i.e., the Dark Cube). In two studies participants responded to the Dark Triad Dirty Dozen, the Taboo Words’ Offensiveness and Usage Inventories (i.e., attitudes towards 30 swear words’ level of offensiveness and usage) (Study 1: N1 = 1,000) and the Sociosexual Orientation Inventory Revised (Study 2: N2 = 309). Participants were clustered according to all eight possible combinations based on their dark trait scores (M/m = high/low Machiavellianism; N/n = high/low narcissism; P/p = high/low psychopathy). The results of this nonlinear approach suggested that the frequent usage, not level of offensiveness, of swear words was associated to Machiavellianism and narcissism. In other words, individuals with high levels in these traits might swear and are verbally offensive often, because they do not see swearing as offensive (cf. with the attitude- behavior-cognition-hypothesis of taboo words; Rosenberg, Sikström & Garcia, 2017). Moreover, promiscuous sociosexual attitude and desire were related to each dark trait only when the other two were low. Additionally, promiscuous sociosexual behavior was not associated to these malevolent character traits. That is, individuals high in the dark traits are willing to and have the desire to engage in sexual relations without closeness, commitment, and other indicators of emotional bonding. However, they do not report high levels of previous sexual experience, relationships, and infidelity. Hence, they approve and desire for it, but they are not actually doing it. The use of person- centered and non-linear methods, such as the Dark Character Cube, seem helpful in the advancement of a coherent theory of a biopsychosocial model of dark character.
13.	Grambow, M., et al. (författare) Using application benchmark call graphs to quantify and improve the practical relevance of microbenchmark suites 2021 Ingår i: Peerj Computer Science. - : PeerJ. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract Performance problems in applications should ideally be detected as soon as they occur, i.e., directly when the causing code modification is added to the code repository. To this end, complex and cost-intensive application benchmarks or lightweight but less relevant microbenchmarks can be added to existing build pipelines to ensure performance goals. In this paper, we show how the practical relevance of microbenchmark suites can be improved and verified based on the application flow during an application benchmark run. We propose an approach to determine the overlap of common function calls between application and microbenchmarks, describe a method which identifies redundant microbenchmarks, and present a recommendation algorithm which reveals relevant functions that are not covered by microbenchmarks yet. A microbenchmark suite optimized in this way can easily test all functions determined to be relevant by application benchmarks after every code change, thus, significantly reducing the risk of undetected performance problems. Our evaluation using two time series databases shows that, depending on the specific application scenario, application benchmarks cover different functions of the system under test. Their respective microbenchmark suites cover between 35.62% and 66.29% of the functions called during the application benchmark, offering substantial room for improvement. Through two use cases-removing redundancies in the microbenchmark suite and recommendation of yet uncovered functions-we decrease the total number of microbenchmarks and increase the practical relevance of both suites. Removing redundancies can significantly reduce the number of microbenchmarks (and thus the execution time as well) to similar to 10% and similar to 23% of the original microbenchmark suites, whereas recommendation identifies up to 26 and 14 newly, uncovered functions to benchmark to improve the relevance. By utilizing the differences and synergies of application benchmarks and microbenchmarks, our approach potentially enables effective software performance assurance with performance tests of multiple granularities.
14.	Granjard, Alexandre, et al. (författare) Occupation and life satisfaction among individuals with mental illness: The mediation role of self-reported psychophysiological health 2021 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 9 Tidskriftsartikel (refereegranskat)abstract Background: Unemployment can diminish physical, psychological and social health. In this context, research shows that people with mental illness have even more difficulties finding occupation. Thus, some countries, such as Sweden, strive after creating job opportunities for this specific group. We investigated the effect of having an occupation on life satisfaction among individuals with mental illness and whether self-reported physical and psychological health mediated the relationship between being (un)employed and life satisfaction. Method: Two-hundred eighty-seven individuals (148 males, 134 females, and 5 missing information) with mental illness, who received support and services from Swedish Municipalities in Blekinge, self-reported occupation, life satisfaction, and physical and psychological health. Results: Participants who reported having an occupation reported also significantly higher levels of life satisfaction, physical health, and psychological health compared to those without occupation. Nevertheless, these differences were rather small (Eta2 < 0.06). Moreover, the indirect effect of having an occupation on life satisfaction through physical and psychological health was significant. Finally, the total indirect effect of physical and psychological health (i.e., psychophysiological health) accounted for 53% of the total effect of having an occupation on life satisfaction. Conclusion: For individuals with mental illness there seems to be an almost equal importance of indirect and direct effects of having an occupation on their levels of life satisfaction. More specifically, while there are differences in life satisfaction within this population in relation to having an occupation, having an occupation leads to the sense of good psychophysiological health, which in turn helps individuals with mental illness to feel satisfied with their lives.
15.	Guo, Yunfang, et al. (författare) Studying the impact of CI on pull request delivery time in open source projects-a conceptual replication 2019 Ingår i: Peerj Computer Science. - : PeerJ. - 2376-5992. ; 5 Tidskriftsartikel (refereegranskat)abstract Nowadays, continuous integration (CI) is indispensable in the software development process. A central promise of adopting CI is that new features or bug fixes can be delivered more quickly. A recent repository mining study by Bernardo, da Costa & Kulesza (2018) found that only about half of the investigated open source projects actually deliver pull requests (PR) faster after adopting CI, with small effect sizes. However, there are some concerns regarding the methodology used by Bernardo et al., which may potentially limit the trustworthiness of this finding. Particularly, they do not explicitly control for normal changes in the pull request delivery time during a project's lifetime (independently of CI introduction). Hence, in our work, we conduct a conceptual replication of this study. In a first step, we replicate their study results using the same subjects and methodology. In a second step, we address the same core research question using an adapted methodology. We use a different statistical method (regression discontinuity design, RDD) that is more robust towards the confounding factor of projects potentially getting faster in delivering PRs over time naturally, and we introduce a control group of comparable projects that never applied CI. Finally, we also evaluate the generalizability of the original findings on a set of new open source projects sampled using the same methodology. We find that the results of the study by Bernardo et al. largely hold in our replication. Using RDD, we do not find robust evidence of projects getting faster at delivering PRs without CI, and we similarly do not see a speed-up in our control group that never introduced CI. Further, results obtained from a newly mined set of projects are comparable to the original findings. In conclusion, we consider the replication successful.
16.	Guo, Yunfang, et al. (författare) Studying the impact of CI on pull request delivery time in open source projects - a conceptual replication 2019 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 5 Tidskriftsartikel (refereegranskat)abstract Nowadays, continuous integration (CI) is indispensable in the software development process. A central promise of adopting CI is that new features or bug fixes can be delivered more quickly. A recent repository mining study by Bernardo, da Costa & Kulesza (2018) found that only about half of the investigated open source projects actually deliver pull requests (PR) faster after adopting CI, with small effect sizes. However, there are some concerns regarding the methodology used by Bernardo et al., which may potentially limit the trustworthiness of this finding. Particularly, they do not explicitly control for normal changes in the pull request delivery time during a project’s lifetime (independently of CI introduction). Hence, in our work, we conduct a conceptual replication of this study. In a first step, we replicate their study results using the same subjects and methodology. In a second step, we address the same core research question using an adapted methodology. We use a different statistical method (regression discontinuity design, RDD) that is more robust towards the confounding factor of projects potentially getting faster in delivering PRs over time naturally, and we introduce a control group of comparable projects that never applied CI. Finally, we also evaluate the generalizability of the original findings on a set of new open source projects sampled using the same methodology. We find that the results of the study by Bernardo et al. largely hold in our replication. Using RDD, we do not find robust evidence of projects getting faster at delivering PRs without CI, and we similarly do not see a speed-up in our control group that never introduced CI. Further, results obtained from a newly mined set of projects are comparable to the original findings. In conclusion, we consider the replication successful.
17.	Habibi, Mojtaba, et al. (författare) Psychometric properties of the Multi- group Ethnic Identity Measure (MEIM) in a sample of Iranian young adults 2021 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 9, s. 1-27 Tidskriftsartikel (refereegranskat)abstract Background: This study examines the factor structure, reliability and test-retest validity of the 12-item Iranian version of the Multi-group Ethnic Identity Measure (MEIM). Additionally, the MEIM’s concurrent validity was tested by investigating the association between ethnic identity and subjective well-being. Method: The scale was translated into Persian language and was administered to 426 students (193 female) at a major public university in Tehran along with the Positive Affect Negative Affect Schedule, and the Satisfaction with Life Scale. Results: The confirmatory factor analysis supported the two-factor first-order commitment, and exploration - consisting of 12 items, and the second-order unidimensional factor structure of general ethnic identity. Moreover, we found evidence for good internal consistency, test re-test reliability, and concurrent validity. Conclusion: The MEIM Persian version was found to be a valid and reliable measure to examine ethnic identity in this Iranian student population, for both males and females. These results support the utility of the Persian version of the MEIM for its use in middle-eastern contexts.
18.	Hebenstreit, Konstantin, et al. (författare) A comparison of chain-of-thought reasoning strategies across datasets and models 2024 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 10, s. 1-13 Tidskriftsartikel (refereegranskat)abstract Emergent chain-of-thought (CoT) reasoning capabilities promise to improve the performance and explainability of large language models (LLMs). However, uncertainties remain about how reasoning strategies formulated for previous model generations generalize to new model generations and different datasets. In this small-scale study, we compare different reasoning strategies induced by zero-shot prompting across six recently released LLMs (davinci-002, davinci-003, GPT-3.5-turbo, GPT-4, Flan-T5- xxl and Cohere command-xlarge). We test them on six question-answering datasets that require real-world knowledge application and logical verbal reasoning, including datasets from scientific and medical domains. Our findings demonstrate that while some variations in effectiveness occur, gains from CoT reasoning strategies remain robust across different models and datasets. GPT-4 benefits the most from current state-of-the-art reasoning strategies and performs best by applying a prompt previously discovered through automated discovery.
19.	Hestetun Thomassen, Jon, et al. (författare) Grab what you can—an evaluation of spatial replication to decrease heterogeneity in sediment eDNA metabarcoding 2021 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 9, s. 1-21 Tidskriftsartikel (refereegranskat)abstract Environmental DNA methods such as metabarcoding have been suggested as possible alternatives or complements to the current practice of morphology-based diversity assessment for characterizing benthic communities in marine sediment. However, the source volume used in sediment eDNA studies is several magnitudes lower than that used in morphological identification. Here, we used data from a North Sea benthic sampling station to investigate to what extent metabarcoding data is affected by sampling bias and spatial heterogeneity. Using three grab parallels, we sampled five separate sediment samples from each grab. We then made five DNA extraction replicates from each sediment sample. Each extract was amplified targeting both the 18S SSU rRNA V1–V2 region for total eukaryotic composition, and the cytochrome c oxidase subunit I (COI) gene for metazoans only. In both datasets, extract replicates from the same sediment sample were significantly more similar than different samples from the same grab. Further, samples from different grabs were less similar than those from the same grab for 18S. Interestingly, this was not true for COI metabarcoding, where the differences within the same grab were similar to the differences between grabs. We also investigated how much of the total identified richness could be covered by extract replicates, individual sediment samples and all sediment samples from a single grab, as well as the variability of Shannon diversity and, for COI, macrofaunal biotic indices indicating environmental status. These results were largely consistent with the beta diversity findings, and show that total eukaryotic diversity can be well represented using 18S metabarcoding with a manageable number of biological replicates. Based on these results, we strongly recommend the combination of different parts of the surface of single grabs for eDNA extraction as well as several grab replicates, or alternatively box cores or similar. This will dilute the effects of dominating species and increase the coverage of alpha diversity. COI-based metabarcoding consistency was found to be lower compared to 18S, but COI macrofauna-based indices were more consistent than direct COI alpha diversity measures.
20.	Hirsch, D., et al. (författare) More ties than we thought 2015 Ingår i: PeerJ. - : PeerJ Inc.. - 2167-8359. ; 2015:1 Tidskriftsartikel (refereegranskat)abstract We extend the existing enumeration of neck tie-knots to include tie-knots with a textured front, tied with the narrow end of a tie. These tie-knots have gained popularity in recent years, based on reconstructions of a costume detail from The Matrix Reloaded, and are explicitly ruled out in the enumeration by Fink & Mao (2000). We show that the relaxed tie-knot description language that comprehensively describes these extended tie-knot classes is context free. It has a regular sub-language that covers all the knots that originally inspired the work. From the full language, we enumerate 266,682 distinct tie-knots that seem tie-able with a normal neck-tie. Out of these 266,682, we also enumerate 24,882 tie-knots that belong to the regular sub-language.
21.	Kashfi, Pariya, 1980, et al. (författare) Integrating User eXperience practices into software development processes: implications of the UX characteristics 2017 Ingår i: Peerj Computer Science. - : PeerJ. - 2376-5992. Tidskriftsartikel (refereegranskat)abstract User eXperience (UX) is a key factor in the success of software systems. Many software companies face challenges in their work with UX. Existing research does not analyze UX practices and challenges in relation to other software quality characteristics or, in particular, in relation to usability. A better understanding of these challenges can help researchers and practitioners better address them in the future. In this empirical study, we have interviewed 17 practitioners with different backgrounds and occupations from eight software development companies. Their responses are coded, and analyzed with thematic analysis. We report eight themes of challenges that practitioners face in their work with UX. While some of these challenges partly overlap with those reported in existing literature about usability or other software quality characteristics, the participants of our study either view many of the challenges as unique to UX, or more severe in the case of UX. Although at a superficial level challenges of x and other quality characteristics overlap, we differentiate these challenges at a deeper level through the five main characteristics of i UX: subjective, holistic, dynamic, context dependent and worthwhile. In particular, we dentified that these characteristics have at least 20 implications (i.e.' additional difficulties) for day-to-day work of practitioners. We found that 11 of these implications have been previously reported in literature, However to the best of our knowledge, the remaining nine implications are unique to our study. These implications can explain why practitioners perceive the challenges to be more severe than for other quality characteristics. Most importantly, they l can explain the industry's lopsided focus on the pragmatic aspect of UX. Our findings can be useful for researchers in identifying new and industry-relevant re search areas and for practitioners to learn from empirically investigated challenges. UX work, and base their improvement efforts on such knowledge. Identifying and investigating the overlaps underlines the importance of these challenges, and can also help finding research areas not only for enhancing UX work but also software quality in general. It also (makes it easier for practitioners to spot, better understand as well as find mitigation strategies for UX, through learning from past experiences and developments in the area of software quality.
22.	Katsikas, Georgios P., 1987-, et al. (författare) SNF: synthesizing high performance NFV service chains 2016 Ingår i: PeerJ Computer Science. - PeerJ, Inc. San Diego CA 92191, San Francisco, USA : PeerJ. - 2376-5992. ; , s. 1-30 Tidskriftsartikel (refereegranskat)abstract In this paper we introduce SNF, a framework that synthesizes (S) network function (NF) service chains by eliminating redundant I/O and repeated elements, while consolidating stateful cross layer packet operations across the chain. SNF uses graph composition and set theory to determine traffic classes handled by a service chain composed of multiple elements. It then synthesizes each traffic class using a minimal set of new elements that apply single-read-single-write and early-discard operations. Our SNF prototype takes a baseline state of the art network functions virtualization (NFV) framework to the level of performance required for practical NFV service deployments. Software-based SNF realizes long (up to 10 NFs) and stateful service chains that achieve line-rate 40 Gbps throughput (up to 8.5x greater than the baseline NFV framework). Hardware-assisted SNF, using a commodity OpenFlow switch, shows that our approach scales at 40 Gbps for Internet Service Provider-level NFV deployments.
23.	Lee, Joonbum, et al. (författare) Investigating the correspondence between driver head position and glance location 2018 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 2018 Tidskriftsartikel (refereegranskat)abstract The relationship between a driver's glance orientation and corresponding head rotation is highly complex due to its nonlinear dependence on the individual, task, and driving context. This paper presents expanded analytic detail and findings from an effort that explored the ability of head pose to serve as an estimator for driver gaze by connecting head rotation data with manually coded gaze region data using both a statistical analysis approach and a predictive (i.e., machine learning) approach. For the latter, classification accuracy increased as visual angles between two glance locations increased. In other words, the greater the shift in gaze, the higher the accuracy of classification. This is an intuitive but important concept that we make explicit through our analysis. The highest accuracy achieved was 83% using the method of Hidden Markov Models (HMM) for the binary gaze classification problem of (a) glances to the forward roadway versus (b) glances to the center stack. Results suggest that although there are individual differences in head-glance correspondence while driving, classifier models based on head-rotation data may be robust to these differences and therefore can serve as reasonable estimators for glance location. The results suggest that driver head pose can be used as a surrogate for eye gaze in several key conditions including the identification of high-eccentricity glances. Inexpensive driver head pose tracking may be a key element in detection systems developed to mitigate driver distraction and inattention.
24.	Mehta, Pooja, et al. (författare) Harvesting social media sentiment analysis to enhance stock market prediction using deep learning 2021 Ingår i: PeerJ Computer Science. - : MDPI. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract Information gathering has become an integral part of assessing people's behaviors and actions. The Internet is used as an online learning site for sharing and exchanging ideas. People can actively give their reviews and recommendations for variety of products and services using popular social sites and personal blogs. Social networking sites, including Twitter, Facebook, and Google+, are examples of the sites used to share opinion. The stock market (SM) is an essential area of the economy and plays a significant role in trade and industry development. Predicting SM movements is a well-known and area of interest to researchers. Social networking perfectly reflects the public's views of current affairs. Financial news stories are thought to have an impact on the return of stock trend prices and many data minin g techniques are used address fluctuations in the SM. Machine learning can provide a more accurate and robust approach to handle SM-related predictions. We sought to identify how movements in a company's stock prices correlate with the expressed opinions (sentiments) of the public about that company. We designed and implemented a stock price prediction accuracy tool considering public sentiment apart from other parameters. The proposed algorithm considers public sentiment, opinions, news and historical stock prices to forecast future stock prices. Our experiments were performed using machine-learning and deep-learning methods including Support Vector Machine, MNB classifier, linear regression, Naive Bayes and Long Short-Term Memory. Our results validate the success of the proposed methodology.
25.	Mkhitaryan, Samvel, et al. (författare) FCMpy : a python module for constructing and analyzing fuzzy cognitive maps 2022 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 8, s. e1078- Tidskriftsartikel (refereegranskat)abstract FCMpy is an open-source Python module for building and analyzing Fuzzy Cognitive Maps (FCMs). The module provides tools for end-to-end projects involving FCMs. It is able to derive fuzzy causal weights from qualitative data or simulating the system behavior. Additionally, it includes machine learning algorithms (e.g., Nonlinear Hebbian Learning, Active Hebbian Learning, Genetic Algorithms, and Deterministic Learning) to adjust the FCM causal weight matrix and to solve classification problems. Finally, users can easily implement scenario analysis by simulating hypothetical interventions (i.e., analyzing what-if scenarios). FCMpy is the first open-source module that contains all the functionalities necessary for FCM oriented projects. This work aims to enable researchers from different areas, such as psychology, cognitive science, or engineering, to easily and efficiently develop and test their FCM models without the need for extensive programming knowledge.
26.	Nima, Ali Al, et al. (författare) Validation of a general subjective well-being factor using Classical Test Theory 2020 Ingår i: PeerJ. - : PeerJ. - 2376-5992 .- 2167-8359. ; 8, s. 1-29 Tidskriftsartikel (refereegranskat)abstract Background: Subjective Well-Being (SWB) is usually conceptualized in terms of an affective (i.e., judgements of biological emotional reactions and experiences) and a cognitive component (i.e., judgements of life satisfaction in relation to a psychological self-imposed ideal). Recently, researchers have suggested that judgements of harmony in life can replace or at least complement the cognitive component of SWB. Here, however, we go beyond that suggestion and propose that harmony in life should be seen as SWB’s social component since it is the sense of balance between the individual and the world around her—a process that comprises acceptance, adaptation, and balance. By adding judgements of one’s social interactions (i.e., harmony in life) to judgments of one’s life satisfaction (psycho) and judgements of one’s emotional reactions (bio), we propose a tentatively biopsychosocial model of SWB. As a first step, we used different factorial models in order to determine if both a general factor and specific sub-factors contribute to the biopsychosocial model of SWB. Method: A total of 527 participants responded to the Positive Affect Negative Affect Schedule (PANAS; 20 items), the Satisfaction with Life Scale (SWLS; five items), and the Harmony in life Scale (HILS; five items). We conducted exploratory and confirmatory factor analyses to validate the biopsychosocial model of subjective well-being and a general factor (SWBS). Results: The 20 PANAS items reflected a mixture of general latent structure saturation and specific latent structure saturation, but contributed to their respective specific latent factor (PA: 48%; NA: 49%) more than to the general latent SWBS factor (positive affect: 25%; negative affect: 32%). The five SWLS items contributed to a larger degree to the general SWBS factor (72%) than to life satisfaction itself (22%), while the five HILS items contributed to even a larger degree to the general SWBS factor (98%) than to harmony in life (0%). The bifactor model was the best model compared with all other models we tested (χ2 = 1660.78, df =375, p < .001; Satorra Bentler χ2 =1265.80, df =375, p < .001; CFI =.92; Tucker-Lewis Index =.91; RMSEA =.067). This model of a general SWBS factor explained about 64% of the total variance in the model, while specific SWBS components together explained 15% of the total variance. Conclusion: Our study suggests SWB as a general factor in a multidimensional biopsychosocial model. Indeed, as much as 64% of the variance of SWB was explained by this general factor. The SWB components, however, contributed to a different degree to each corresponding factor in the model. For instance, while the affective and cognitive components seem to be their own constructs and also part of the general SWB factor, the social component tested here contributed 0% to its own variance but 98% to the general factor.
27.	Qadri, Azam Mehmood, et al. (författare) Heart failure survival prediction using novel transfer learning based probabilistic features 2024 Ingår i: PeerJ Computer Science. - : PEERJ INC. - 2376-5992. ; 10 Tidskriftsartikel (refereegranskat)abstract Heart failure is a complex cardiovascular condition characterized by the heart's inability to pump blood effectively, leading to a cascade of physiological changes. Predicting survival in heart failure patients is crucial for optimizing patient care and resource allocation. This research aims to develop a robust survival prediction model for heart failure patients using advanced machine learning techniques. We analyzed data from 299 hospitalized heart failure patients, addressing the issue of imbalanced data with the Synthetic Minority Oversampling (SMOTE) method. Additionally, we proposed a novel transfer learning-based feature engineering approach that generates a new probabilistic feature set from patient data using ensemble trees. Nine fine-tuned machine learning models are built and compared to evaluate performance in patient survival prediction. Our novel transfer learning mechanism applied to the random forest model outperformed other models and state-of-the-art studies, achieving a remarkable accuracy of 0.975. All models underwent evaluation using 10-fold crossvalidation and tuning through hyperparameter optimization. The findings of this study have the potential to advance the field of cardiovascular medicine by providing more accurate and personalized prognostic assessments for individuals with heart failure.
28.	Semeniuta, Oleksandr, 1990, et al. (författare) EPypes: a framework for building event-driven data processing pipelines 2019 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 2019:2 Tidskriftsartikel (refereegranskat)abstract Many data processing systems are naturally modeled as pipelines, where data flows though a network of computational procedures. This representation is particularly suitable for computer vision algorithms, which in most cases possess complex logic and a big number of parameters to tune. In addition, online vision systems, such as those in the industrial automation context, have to communicate with other distributed nodes. When developing a vision system, one normally proceeds from ad hoc experimentation and prototyping to highly structured system integration. The early stages of this continuum are characterized with the challenges of developing a feasible algorithm, while the latter deal with composing the vision function with other components in a networked environment. In between, one strives to manage the complexity of the developed system, as well as to preserve existing knowledge. To tackle these challenges, this paper presents EPypes, an architecture and Python-based software framework for developing vision algorithms in a form of computational graphs and their integration with distributed systems based on publish-subscribe communication. EPypes facilitates flexibility of algorithm prototyping, as well as provides a structured approach to managing algorithm logic and exposing the developed pipelines as a part of online systems.
29.	Semeniuta, Oleksandr, et al. (författare) Event-driven industrial robot control architecture for the Adept V+ platform 2019 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 2019:7 Tidskriftsartikel (refereegranskat)abstract Modern industrial robotic systems are highly interconnected. They operate in a distributed environment and communicate with sensors, computer vision systems, mechatronic devices, and computational components. On the fundamental level, communication and coordination between all parties in such distributed system are characterized by discrete event behavior. The latter is largely attributed to the specifics of communication over the network, which, in terms, facilitates asynchronous programming and explicit event handling. In addition, on the conceptual level, events are an important building block for realizing reactivity and coordination. Eventdriven architecture has manifested its effectiveness for building loosely-coupled systems based on publish-subscribe middleware, either general-purpose or robotic-oriented. Despite all the advances in middleware, industrial robots remain difficult to program in context of distributed systems, to a large extent due to the limitation of the native robot platforms. This paper proposes an architecture for flexible event-based control of industrial robots based on the Adept V+ platform. The architecture is based on the robot controller providing a TCP/IP server and a collection of robot skills, and a high-level control module deployed to a dedicated computing device. The control module possesses bidirectional communication with the robot controller and publish/subscribe messaging with external systems. It is programmed in asynchronous style using pyadept, a Python library based on Python coroutines, AsyncIO event loop and ZeroMQ middleware. The proposed solution facilitates integration of Adept robots into distributed environments and building more flexible robotic solutions with eventbased logic.
30.	Srivastava, Arpan, et al. (författare) Deep learning based respiratory sound analysis for detection of chronic obstructive pulmonary disease 2021 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract In recent times, technologies such as machine learning and deep learning have played a vital role in providing assistive solutions to a medical domain’s challenges. They also improve predictive accuracy for early and timely disease detection using medical imaging and audio analysis. Due to the scarcity of trained human resources, medical practitioners are welcoming such technology assistance as it provides a helping hand to them in coping with more patients. Apart from critical health diseases such as cancer and diabetes, the impact of respiratory diseases is also gradually on the rise and is becoming life-threatening for society. The early diagnosis and immediate treatment are crucial in respiratory diseases, and hence the audio of the respiratory sounds is proving very beneficial along with chest X-rays. The presented research work aims to apply Convolutional Neural Network based deep learning methodologies to assist medical experts by providing a detailed and rigorous analysis of the medical respiratory audio data for Chronic Obstructive Pulmonary detection. In the conducted experiments, we have used a Librosa machine learning library features such as MFCC, Mel-Spectrogram, Chroma, Chroma (Constant-Q) and Chroma CENS. The presented system could also interpret the severity of the disease identified, such as mild, moderate, or acute. The investigation results validate the success of the proposed deep learning approach. The system classification accuracy has been enhanced to an ICBHI score of 93%. Furthermore, in the conducted experiments, we have applied K-fold Cross-Validation with ten splits to optimize the performance of the presented deep learning approach.
31.	Striegl, Julian, et al. (författare) Deep learning-based dimensional emotion recognition for conversational agent-based cognitive behavioral therapy 2024 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 10 Tidskriftsartikel (refereegranskat)abstract Internet-based cognitive behavioral therapy (iCBT) offers a scalable, cost-effective, accessible, and low-threshold form of psychotherapy. Recent advancements explored the use of conversational agents such as chatbots and voice assistants to enhance the delivery of iCBT. These agents can deliver iCBT-based exercises, recognize and track emotional states, assess therapy progress, convey empathy, and potentially predict longterm therapy outcome. However, existing systems predominantly utilize categorical approaches for emotional modeling, which can oversimplify the complexity of human emotional states. To address this, we developed a transformer-based model for dimensional text-based emotion recognition, fine-tuned with a novel, comprehensive dimensional emotion dataset comprising 75,503 samples. This model significantly outperforms existing state-of-the-art models in detecting the dimensions of valence, arousal, and dominance, achieving a Pearson correlation coefficient of r = 0 . 90, r = 0 . 77, and r = 0 . 64, respectively. Furthermore, a feasibility study involving 20 participants confirmed the model's technical effectiveness and its usability, acceptance, and empathic understanding in a conversational agent-based iCBT setting, marking a substantial improvement in personalized and effective therapy experiences.
32.	Tavara, Shirin, et al. (författare) Effects of network topology on the performance of consensus and distributed learning of SVMs using ADMM 2021 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 7 Tidskriftsartikel (refereegranskat)abstract The Alternating Direction Method of Multipliers (ADMM) is a popular and promising distributed framework for solving large-scale machine learning problems. We consider decentralized consensus-based ADMM in which nodes may only communicate with one-hop neighbors. This may cause slow convergence. We investigate the impact of network topology on the performance of an ADMM-based learning of Support Vector Machine using expander, and mean-degree graphs, and additionally some of the common modern network topologies. In particular, we investigate to which degree the expansion property of the network influences the convergence in terms of iterations, training and communication time. We furthermore suggest which topology is preferable. Additionally, we provide an implementation that makes these theoretical advances easily available. The results show that the performance of decentralized ADMM-based learning of SVMs in terms of convergence is improved using graphs with large spectral gaps, higher and homogeneous degrees.
33.	Thörn, Jonathan, et al. (författare) Quality assuring the quality assurance tool : Applying safety-critical concepts to test framework development 2022 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 8, s. e1131-e1131 Tidskriftsartikel (refereegranskat)abstract The quality of embedded systems is demonstrated by the performed tests. The quality of such tests is often dependent on the quality of one or more testing tools, especially in automated testing. Test automation is also central to the success of agile development. It is thus critical to ensure the quality of testing tools. This work explores how industries with agile processes can learn from safety-critical system development with regards to the quality assurance of the test framework development. Safety-critical systems typically need adherence to safety standards that often suggests substantial upfront documentation, plans and a long-term perspective on several development aspects. In contrast, agile approaches focus on quick adaptation, evolving software and incremental deliveries. This article identifies several approaches of quality assurance of software development tools in functional safety development and agile development. The extracted approaches are further analyzed and processed into candidate solutions, i.e., principles and practices for the test framework quality assurance applicable in an industrial context. An industrial focus group with experienced practitioners further validated the candidate solutions through moderated group discussions. The two main contributions from this study are: (i) 48 approaches and 25 derived candidate solutions for test framework quality assurance in four categories (development, analysis, run-time measures, and validation and verification) with related insights, e.g., a test framework should be perceived as a tool-chain and not a single tool, (ii) the perceived value of the candidate solutions in industry as collected from the focus group.
34.	Verdecchia, Roberto, et al. (författare) Empirical evaluation of an architectural technical debt index in the context of the Apache and ONAP ecosystems 2022 Ingår i: PeerJ Computer Science. - : PeerJ. - 2376-5992. ; 8 Tidskriftsartikel (refereegranskat)abstract Background. Architectural Technical Debt (ATD) in a software-intensive system denotes architectural design choices which, while being suitable or even optimal when adopted, lower the maintainability and evolvability of the system in the long term, hindering future development activities. Despite the growing research interest in ATD, how to gain an informative and encompassing viewpoint of the ATD present in a software-intensive system is still an open problem. Objective. In this study, we evaluate ATDx, a data-driven approach providing an overview of the ATD present in a software-intensive system. The approach, based on the analysis of a software portfolio, calculates severity levels of architectural rule violations via a clustering algorithm, and aggregates results into different ATD dimensions. Method. To evaluate ATDx, we implement an instance of the approach based on SonarQube, and run the analysis on the Apache and ONAP ecosystems. The analysis results are then shared with the portfolio contributors, who are invited to participate in an online survey designed to evaluate the representativeness and actionability of the approach. Results. The survey results confirm the representativeness of the ATDx, in terms of both the ATDx analysis results and the used architectural technical debt dimensions. Results also showed the actionability of the approach, although to a lower extent when compared to the ATDx representativeness, with usage scenarios including refactoring, code review, communication, and ATD evolution analysis. Conclusions. With ATDx, we strive for the establishment of a sound, comprehensive, and intuitive architectural view of the ATD identifiable via source code analysis. The collected results are promising, and display both the representativeness and actionability of the approach. As future work, we plan to consolidate the approach via further empirical experimentation, by considering other development contexts (e.g., proprietary portfolios and other source code analysis tools), and enhancing the ATDx report capabilities.

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