Effective Bug Triage based on Historical Bug-Fix Information

International audienceFor complex and popular software, project teams could receive a large number of bug reports. It is often tedious and costly to manually assign these bug reports to developers who have the expertise to fix the bugs. Many bug triage techniques have been proposed to automate this process. In this pa-per, we describe our study on applying conventional bug triage techniques to projects of different sizes. We find that the effectiveness of a bug triage technique largely depends on the size of a project team (measured in terms of the number of developers). The conventional bug triage methods become less effective when the number of developers increases. To further improve the effectiveness of bug triage for large projects, we propose a novel recommendation method called BugFixer, which recommends developers for a new bug report based on historical bug-fix in-formation. BugFixer constructs a Developer-Component-Bug (DCB) network, which models the relationship between developers and source code components, as well as the relationship be-tween the components and their associated bugs. A DCB network captures the knowledge of "who fixed what, where". For a new bug report, BugFixer uses a DCB network to recommend to triager a list of suitable developers who could fix this bug. We evaluate BugFixer on three large-scale open source projects and two smaller industrial projects. The experimental results show that the proposed method outperforms the existing methods for large projects and achieves comparable performance for small projects

2-(4-Bromo­phen­yl)-3,4-dihydro­isoquinolin-2-ium thio­cyanate hemihydrate

In the title hemihydrated salt, C15H13BrN+·NCS−·0.5H2O, the two benzene rings are aligned at a dihedral angle of 46.9 (1)°. The six-membered heterocycle of the dihydro­isoquinoline unit adopts a half-chair conformation. The water mol­ecule and thio­cyanate ion are linked by O—H⋯N hydrogen bonds, generating a four-membered ring motif. In addition, C—H⋯O and C—H⋯S inter­actions link the components into a chain along the c axis. π–π inter­actions [centroid–centroid distance = 3.974 (2) Å] link the chains into sheets and further π—π [centroid–centroid distance = 3.746 (2) Å] and C—H⋯π inter­actions give rise to a three-dimensional nework

Performance of digital image correction technique for mild steel with different strain hardening effects

This paper investigates the performance of Digital Image Correction (DIC) technique in determining the initial fracture toughness of mild steel with different strain hardening effects. To achieve this goal, the results of DIC technique-based method are compared with those of the commonly used unloading compliance (UC) method. The comparison results reveal that the DIC technique-based method exhibit a good agreement with the UC method in determining initial fracture toughness, with a deviation of less than 3.0 %. Additionally, the DIC technique-based method demonstrates the consistency in determining the initial fracture toughness, independent of the ratio of initial pre-crack length to width. Furthermore, the importance of strain hardening effects on initial fracture toughness follows the order of strain hardening capacity, effective yield stress, and yield offset. The significance of this paper is that it provides a deep understanding of the performance of the DIC technique in determining the initial fracture toughness of mild steel.</p

On the Quantum Mechanics for One Photon

This paper revisits the quantum mechanics for one photon from the modern viewpoint and by the geometrical method. Especially, besides the ordinary (rectangular) momentum representation, we provide an explicit derivation for the other two important representations, called the cylindrically symmetrical representation and the spherically symmetrical representation, respectively. These other two representations are relevant to some current photon experiments in quantum optics. In addition, the latter is useful for us to extract the information on the quantized black holes. The framework and approach presented here are also applicable to other particles with arbitrary mass and spin, such as the particle with spin 1/2.Comment: 15 pages, typos corrected, references added, corrections and improvements made owing to the anonymous referee's responsible and helpful remarks, accepted for publication in Journal of Mathematical Physics:

Experimental study of PLLA/INH slow release implant fabricated by three dimensional printing technique and drug release characteristics in vitro

BACKGROUND: Local slow release implant provided long term and stable drug release in the lesion. The objective of this study was to fabricate biodegradable slow release INH/PLLA tablet via 3 dimensional printing technique (3DP) and to compare the drug release characteristics of three different structured tablets in vitro. METHODS: Three different drug delivery systems (columnar-shaped tablet (CST), doughnut-shaped tablet (DST) and multilayer doughnut-shaped tablet (MDST)) were manufactured by the three dimensional printing machine and isoniazid was loaded into the implant. Dynamic soaking method was used to study the drug release characteristics of the three implants. MTT cytotoxicity test and direct contact test were utilized to study the biocompatibility of the implant. The microstructures of the implants’ surfaces were observed with electron microscope. RESULTS: The PLLA powder in the tablet could be excellently combined through 3DP without disintegration. Electron microscope observations showed that INH distributed evenly on the surface of the tablet in a “nest-shaped” way, while the surface of the barrier layer in the multilayer doughnut shaped tablet was compact and did not contain INH. The concentration of INH in all of the three tablets were still higher than the effective bacteriostasis concentration (Isoniazid: 0.025 ~ 0.05 μg/ml) after 30 day’s release in vitro. All of the tablets showed initial burst release of the INH in the early period. Drug concentration of MDST became stable and had little fluctuation starting from the 6th day of the release. Drug concentration of DST and CST decreased gradually and the rate of decrease in concentration was faster in DST than CST. MTT cytotoxicity test and direct contact test indicated that the INH-PLLA tablet had low cytotoxicity and favorable biocompatibility. CONCLUSIONS: Three dimensional printing technique was a reliable technique to fabricate complicated implants. Drug release pattern in MDST was the most stable among the three implants. It was an ideal drug delivery system for the antibiotics. Biocompatibility tests demonstrated that the INH-PLLA implant did not have cytotoxicity. The multilayer donut-shaped tablet provided a new constant slow release method after an initial burst for the topical application of the antibiotic

The feasibility and implementation of a golden beam model in Monaco treatment planning system

Background and purpose: Accelerated go live (AGL) is the entire management process for medical accelerators from installation, commissioning, modeling to radiotherapy implementation. Compared with the traditional time-consuming accelerator acceptance process, AGL has established a set of gold standard models based on the big data of thousands of medical accelerators, which makes the accelerator installation greatly optimized in the data acquisition and modeling stage. This study aimed to evaluate and verify an efficient beam modeling method for Monaco treatment planning system (TPS) using golden beam data (GBD). Methods: Two Elekta Infinity™ linear accelerators with agility head in the Department of Radiation Oncology, Fudan University Shanghai Cancer Center, were installed and matched with the GBD. Then, a customer acceptance test (CAT) and beam model validations were performed on measured percentage depth dose (PDD) and profile for open-field (OF) point-doses in a three-dimensional water tank. Furthermore, a total of 16 clinical cases from different sites were used for radiotherapy planning design, measurement and dose analysis to validate and verify the accuracy of the beam model. Results: For beam model verification, the agreement of all validation PDD and profile was larger than 90%, and the majority point passing rate was larger than 95% (99.4% for linac 1 and 98.5% for linac 2). For point-dose validation, 96.8% and 97.2% of OF point measured were found to be within 2% agreement of TPS-calculations for linac 1 and linac 2, respectively. The deviation of R50 and R90 between TPS calculation and measured were within 3 mm at all evaluated points of electron beam. The Gamma passing rate for all plans was greater than 90% when using 3%/3 mm criteria, and point-dose agreement was within 3%. Conclusion: Compared with the traditional accelerator process from installation to commission, the Monaco TPS modeling process AGL based on GBD can not only ensure the model accuracy, but also shorten the entire process time, which has the feasibility of clinical application

Characteristics and Mechanism of Pb2+ Adsorption From Aqueous Solution Onto Biochar Derived From Microalgae and Chitosan-Modified Microalgae

With increasing aquatic heavy metal pollution and eutrophication, using algae to prepare novel adsorbent materials for remediating heavy metal pollution has recently attracted research attention worldwide. However, microalgae biochar exhibits poor adsorption capacity in certain conditions, and little is known regarding microalgae biochar modification using chitosan. Chitosan has been previously used to directly modify microalgae biochar; however, in this study, chitosan is used to modify algae powder used to prepare biochar. Therefore, in this study, chitosan was used as a microalgae biochar modifier to enhance its applicability and adsorption capacity. Accordingly, two new types of microalgae biochars, chitosan-biochar (CTS-BC) and biochar-chitosan (BC-CTS), were developed as an adsorbent material using Clostridium and adding chitosan as a modifier at different stages of its preparation. These developed microalgae biochars were characterized using Brunauer–Emmett–Teller surface area,X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. The adsorption processes of these biochars can be well described by a pseudo-second-order kinetic model. Pb2+ was dominantly adsorbed by microalgal biochar through chemisorption. Following chitosan modification, several mino, cyano, and aromatic ring groups were attached onto the surface of the microalgal biochar. The Pb2+ adsorption capacity of the chitosan-modified biochar was better than that of the unmodified biochar. The maximum Pb2+ adsorption capacity of CTS-BC under acidic conditions (pH = 5) was 9.41 mg g−1, whereas that of BC-CTS under alkaline conditions (pH = 9) was 9.94 mg g−1, both were higher than that of unmodified microalgae biochar under similar conditions. CTS-BC and BC-CTS possessed excellent stability and reusability for Pb(II) adsorption, the adsorption efficiency still remained above 50% even after three cycles. This study demonstrated that adsorbent materials having a stronger heavy-metal adsorption capacity can be prepared by adding chitosan during different stages of the microalgae biochar preparation process

Contact force sensor based on microfiber Bragg grating

We demonstrate a miniature contact force sensor based on a 30-µm diameter microfiber Bragg grating packaged with a conforming elastomer material features extremely high sensitivity up to 0.8-mN to contract force.Department of Electrical EngineeringDepartment of Electronic and Information Engineerin

Changes and driving forces analysis of alpine wetlands in the first meander of the Yellow River based on long-term time series remote sensing data

IntroductionAs a vital component of the ecosystem of the Qinghai-Tibet Plateau, alpine wetlands coexist with their vulnerability, sensitivity, and abundant biodiversity, propelling the material cycle and energy flux of the entire plateau ecosystem. In recent decades, climate change and human activities have significantly altered the regional landscape. Monitoring and assessing changes in the alpine wetlands on the Qinghai-Tibet Plateau requires the efficient and accurate collection of long-term information.MethodsHere, we interpreted the remote sensing data of the first meander of the Yellow River of alpine wetlands from 1990 to 2020 based on Google Earth Engine (GEE) platform, using geographic information system (GIS) and landscape pattern index to analyze the spatial and temporal evolution of wetland landscape patterns, and the primary drivers of changes in wetland area were explored by GeoDetector.ResultsOur result showed that most wetland areas were found in regions with gradients less than 12° and elevations between 3315 and 3600 m. From 1990 to 2010, the area of alpine wetland in the study area decreased by 25.43%. During the period between 2010 and 2020 to the 1990s, the wetland area decreased by 322.9 km2. Conversion to and from grassland was the primary form of wetland transfer out and in, respectively. The overall migration of the wetland centroid in the study area was to the southwest between 1990 and 2010 and to the north between 2010 and 2020. The geometry of the wetland landscape was relatively simple, the landscape was relatively intact, and patches retained a high level of agglomeration and connectivity. However, their level of agglomeration and connectivity was disrupted. A quantitative analysis of the factor detector in GeoDetector revealed that the DEM, slope, and evaporation were the most important driving factors influencing the change of wetland area, with socioeconomic development also influencing changes in the wetland area to a lesser extent.DiscussionUsing interaction detectors, it was discovered that the interaction of various driving factors could better explain the long-term variations in wetland areas, with a greater degree of explanation than that of each driving factor alone