Vladimir Filkov

ORCID: 0000-0003-0492-4393
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About
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Research Areas
  • Software Engineering Research
  • Open Source Software Innovations
  • Bioinformatics and Genomic Networks
  • Complex Network Analysis Techniques
  • Gene expression and cancer classification
  • Knowledge Management and Sharing
  • Software Engineering Techniques and Practices
  • Software System Performance and Reliability
  • Scientific Computing and Data Management
  • Mobile Crowdsensing and Crowdsourcing
  • Gene Regulatory Network Analysis
  • Wikis in Education and Collaboration
  • Plant Molecular Biology Research
  • Genomics and Chromatin Dynamics
  • Software Reliability and Analysis Research
  • Advanced Data Processing Techniques
  • Big Data and Business Intelligence
  • Microbial Metabolic Engineering and Bioproduction
  • Expert finding and Q&A systems
  • Topic Modeling
  • Plant Gene Expression Analysis
  • BIM and Construction Integration
  • Genetic Mapping and Diversity in Plants and Animals
  • Advanced Software Engineering Methodologies
  • Opinion Dynamics and Social Influence

University of California, Davis
2016-2025

University of California Davis Medical Center
2023

University of California System
2013-2022

Agricultural Research Service
2011

United States Department of Agriculture
2011

Stony Brook University
1999-2002

State University of New York
2002

Laboratoire d'Informatique de Paris-Nord
2002

What is the effect of programming languages on software quality? This question has been a topic much debate for very long time. In this study, we gather large data set from GitHub (729 projects, 80 Million SLOC, 29,000 authors, 1.5 million commits, in 17 languages) an attempt to shed some empirical light question. reasonably sample size allows us use mixed-methods approach, combining multiple regression modeling with visualization and text analytics, study language features such as static...

10.1145/2635868.2635922 article EN 2014-11-04

Software processes comprise many steps; coding is followed by building, integration testing, system deployment, operations, among others. process and automation have been areas of key concern in software engineering, ever since the pioneering work Osterweil; market pressures for Agility, open, decentralized, development provided additional progress this area. But do these innovations actually help projects? Given numerous confounding factors that can influence project performance, it be a...

10.1145/2786805.2786850 article EN 2015-08-26

Software engineering researchers have long been interested in where and why bugs occur code, predicting they might turn up next. Historical bug-occurence data has key to this research. Bug tracking systems, code version histories, record when, how by whom were fixed; from these sources, datasets that relate file changes bug fixes can be extracted. These historical used test hypotheses concerning processes of introduction, also build statistical prediction models. Unfortunately, humans are...

10.1145/1595696.1595716 article EN 2009-08-24

Software development is usually a collaborative venture. Open Source (OSS) projects are no exception; indeed, by design, the OSS approach can accommodate teams that more open, geographically distributed, and dynamic than commercial teams. This, we find, leads to quite diverse. Team diversity, predominantly in offline groups, known correlate with team output, mostly positive effects. How about OSS? Using GitHub, largest publicly available collection of projects, studied how gender tenure...

10.1145/2702123.2702549 article EN 2015-04-17

Commercial software project managers design organizational structure carefully, mindful of available skills, division labour, geographical boundaries, etc. These "cathedrals" are to be contrasted with the "bazaar-like" nature Open Source Software (OSS) Projects, which have no pre-designed structure. Any that exists is dynamic, self-organizing, latent, and usually not explicitly stated. Still, in large, complex, successful, OSS projects, we do expect subcommunities will form spontaneously...

10.1145/1453101.1453107 article EN 2008-11-09

Stack Overflow is a popular on-line programming question and answer community providing its participants with rapid access to knowledge expertise of their peers, especially benefitting coders. Despite the popularity Overflow, role in work cycle open-source developers yet be understood: on one hand, participation it has potential increase individual thus improving speeding up development process. On other may interrupt regular working rhythm developer, hence also possibly slow down In this...

10.1109/socialcom.2013.35 article EN International Conference on Social Computing 2013-09-01

Abstract Discovery of rare mutations in populations requires methods, such as TILLING (for Targeting Induced Local Lesions Genomes), for processing and analyzing many individuals parallel. Previous protocols employed enzymatic or physical discrimination heteroduplexed from homoduplexed target DNA. Using mutant rice (Oryza sativa) wheat (Triticum durum), we developed a method based on Illumina sequencing genes amplified multidimensionally pooled templates representing 768 per experiment....

10.1104/pp.110.169748 article EN cc-by PLANT PHYSIOLOGY 2011-04-29

Historically, mailing lists have been the preferred means for coordinating development and user support activities. With emergence popularity growth of social Q&A sites such as StackExchange network (e.g., StackOverflow), this is beginning to change. Such offer different socio-technical incentives their participants than do, e.g., rich web environments store manage content collaboratively, or a place showcase knowledge expertise more vividly peers potential recruiters. A key difference...

10.1145/2531602.2531659 article EN 2014-02-07

Continuous Integration (CI) has become a disruptive innovation in software development: with proper tool support and adoption, positive effects have been demonstrated for pull request throughput scaling up of project sizes. As any other innovation, adopting CI implies adapting existing practices order to take full advantage its potential, "best practices" that end proposed. Here we study the adaptation evolution code writing submission, issue closing, testing as TRAVIS is adopted by hundreds...

10.1109/ase.2017.8115619 article EN 2017-10-01

The pull-based development model, enabled by git and popularised collaborative coding platforms like Bit Bucket, Gitorius, GitHub, is widely used in distributed software teams. While this model lowers the barrier to entry for potential contributors (since anyone can submit pull requests any repository), it also increases burden on integrators (i.e., Members of a project's core team, responsible evaluating proposed changes integrating them into main line), who struggle keep up with volume...

10.1109/msr.2015.42 article EN 2015-05-01

The team aspects of software engineering have been a subject great interest since early work by Fred Brooks and others: how well do people together in teams? why join what happens if teams are distributed? Recently, the emergence project ecosystems such as GitHub created an entirely new, higher level organization. supports numerous teams; they share common technical platform (for activities) social (via following, commenting, etc). We explore evidence for socialization precursor to joining...

10.1145/2786805.2786854 article EN 2015-08-26

The pull-based development model, enabled by git and popularised collaborative coding platforms like Bit Bucket, Gitorius, GitHub, is widely used in distributed software teams. While this model lowers the barrier to entry for potential contributors (since anyone can submit pull requests any repository), it also increases burden on integrators (i.e., Members of a project's core team, responsible evaluating proposed changes integrating them into main line), who struggle keep up with volume...

10.5555/2820518.2820564 article EN Mining Software Repositories 2015-05-16

Significance While all eukaryotic circadian clocks depend on transcriptional feedback loops, the plant network is uniquely complex. An apparent redundancy in clock two types of transcription factors that antagonistically regulate common target genes. Here, we show that, although loss either repressor- or activator-type perturbs pace and development, simultaneous both restores near–wild-type development largely rescues period phase phenotypes at ambient temperatures. However, higher-order...

10.1073/pnas.1805524115 article EN Proceedings of the National Academy of Sciences 2018-06-18

Angiosperm trees reorient their woody stems by asymmetrically producing a specialized xylem tissue, tension wood, which exerts strong contractile force resulting in negative gravitropism of the stem. Here, we show, Populus trees, that initial gravity perception and response occurs cells through sedimentation starch-filled amyloplasts relocalization auxin transport protein, PIN3. Gibberellic acid treatment stimulates rate wood formation gravibending enhances tissue-specific expression an...

10.1105/tpc.15.00531 article EN The Plant Cell 2015-09-26

Abstract Purpose To explore the information in routine digital subtraction angiography (DSA) and evaluate deep learning algorithms for automated identification of anatomic location DSA sequences. Methods abdominal aorta, celiac, superior mesenteric, inferior bilateral external iliac arteries was labeled with from retrospectively collected endovascular procedures performed between 2010 2020 at a tertiary care medical center. “Key” images within each sequence demonstrating parent vessel first...

10.1007/s10278-024-01351-z article EN cc-by Deleted Journal 2025-01-09

We address possible limitations of publicly available data sets yeast gene expression. study the predictability known regulators via time-series analysis, and show that less than 20% regulatory pairs exhibit strong correlations in Cho/Spellman sets. By analyzing relationships, we designed an edge detection function which identified candidate regulations with greater fidelity standard correlation methods. develop general methods for integrated analysis coarse These include 1) automated period...

10.1089/10665270252935485 article EN Journal of Computational Biology 2002-04-01

With the exploding volume of microarray experiments comes increasing interest in mining repositories such data. Meaningfully combining results from varied on an equal basis is a challenging task. Here we propose general method for integrating heterogeneous data sets based consensus clustering formalism. Our analyzes source-specific clusterings and identifies set-partition which as close possible to all them. We develop criterion assess potential benefit multiple sets, i.e. whether integrated...

10.1142/s0218213004001867 article EN International Journal of Artificial Intelligence Tools 2004-12-01

Software systems are decomposed hierarchically, for example, into modules, packages and files. This hierarchical decomposition has a profound influence on evolvability, maintainability work assignment. Hierarchical is thus clearly of central concern empirical software engineering researchers; but it also poses quandary. At what level do we study phenomena, such as quality, distribution, collaboration productivity? the files? packages? or modules? How does affect truth, meaning, relevance...

10.1109/ase.2011.6100074 article EN 2021 36th IEEE/ACM International Conference on Automated Software Engineering (ASE) 2011-11-01

Code reuse has well-known benefits on code quality, coding efficiency, and maintenance. Open Source Software (OSS) programmers gladly share their own they happily others'. Social programming platforms like GitHub have normalized foraging via common platforms, enabling search across different projects. Removing project borders may facilitate more efficient foraging, consequently faster programming. But looking for projects takes longer and, once found, be challenging to tailor one's needs....

10.1109/msr.2017.15 article EN 2017-05-01

Software development has always inherently required multitasking: developers switch between coding, reviewing, testing, designing, and meeting with colleagues. The advent of software ecosystems like GitHub enabled something new: the ability to easily projects. Developers also have social incentives contribute many projects; prolific contributors gain recognition (eventually) economic rewards. Multitasking, however, comes at a cognitive cost: frequent context-switches can lead distraction,...

10.1145/2884781.2884875 article EN Proceedings of the 44th International Conference on Software Engineering 2016-05-13

Security policies, which specify what applications are allowed to do, notoriously difficult correctly. Many were found request over-liberal permissions. On mobile platforms, this might prevent a cautious user from installing an otherwise harmless application or, even worse, increase the attack surface in vulnerable applications. As result of such difficulties, programmers frequently ask about them on-line fora. Our goal is gain some insight into both misuse permissions and discussions We...

10.1109/msr.2013.6624000 article EN 2013-05-01

Social synchrony (SS) is an emergent phenomenon in human society. People often mimic others which, over time, can result large groups behaving similarly. Drawing from prior empirical studies of SS online communities, here we propose a discrete network model based on four attributes: 1) depth action; 2) breadth impact, i.e., number actions are performed with group people involved; 3) heterogeneity role, higher degree play more important roles; and 4) lastly, emergence phenomenon, it far...

10.1109/tcyb.2017.2696998 article EN IEEE Transactions on Cybernetics 2017-05-12

Software defect prediction aims to automatically locate defective code modules better focus testing resources and human effort. Typically, software pipelines are comprised of two parts: the first extracts program features, like abstract syntax trees, by using external tools, second applies machine learning-based classification models those features in order predict modules. Since such approaches depend on specific feature extraction learning classifiers have be custom-tailored effectively...

10.1145/3377811.3380389 article EN 2020-06-27

Understanding one's work environment is important for success, especially when working in teams. In virtual collaborative environments this amounts to being aware of the technical and social attributes team members. Focusing on Open Source Software teams, naturally very diverse both socially technically, we report results a user survey that tries resolve how teamwork individual are perceived by developers collaborating GITHUB, those perceptions influence their work. Our findings can be used...

10.1109/chase.2015.14 article EN 2015-05-01
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