1,456 research outputs found
Automated visual classification of DOM-based presentation failure reports for responsive web pages
No full textSince it is common for the users of a web page to access it through a wide variety of devices—including desktops, laptops, tablets and phones—web developers rely on responsive web design (RWD) principles and frameworks to create sites that are useful on all devices. A correctly implemented responsive web page adjusts its layout according to the viewport width of the device in use, thereby ensuring that its design suitably features the content. Since the use of complex RWD frameworks often leads to web pages with hard‐to‐detect responsive layout failures (RLFs), developers employ testing tools that generate reports of potential RLFs. Since testing tools for responsive web pages, like ReDeCheck, analyse a web page representation called the Document Object Model (DOM), they may inadvertently flag concerns that are not human visible, thereby requiring developers to manually confirm and classify each potential RLF as a true positive (TP), false positive (FP), or non‐observable issue (NOI)—a process that is time consuming and error prone. The conference version of this paper presented Viser, a tool that automatically classified three types of RLFs reported by ReDeCheck. Since Viser was not designed to automatically confirm and classify two types of RLFs that ReDeCheck's DOM‐based analysis could surface, this paper introduces Verve, a tool that automatically classifies all RLF types reported by ReDeCheck. Along with manipulating the opacity of HTML elements in a web page, as does Viser, the Verve tool also uses histogram‐based image comparison to classify RLFs in web pages. Incorporating both the 25 web pages used in prior experiments and 20 new pages not previously considered, this paper's empirical study reveals that Verve's classification of all five types of RLFs frequently agrees with classifications produced manually by humans. The experiments also reveal that Verve took on average about 4 s to classify any of the RLFs among the 469 reported by ReDeCheck. Since this paper demonstrates that classifying an RLF as a TP, FP, or NOI with Verve, a publicly available tool, is less subjective and error prone than the same manual process done by a human web developer, we argue that it is well‐suited for supporting the testing of complex responsive web pages
The Effectiveness of Test Coverage Criteria for Relational Database Schema Integrity Constraints
No full textDespite industry advice to the contrary, there has been little work that has sought to test that a relational database's schema has correctly specified integrity constraints. These critically important constraints ensure the coherence of data in a database, defending it from manipulations that could violate requirements such as “usernames must be unique” or “the host name cannot be missing or unknown.” This article is the first to propose coverage criteria, derived from logic coverage criteria, that establish different levels of testing for the formulation of integrity constraints in a database schema. These range from simple criteria that mandate the testing of successful and unsuccessful INSERT statements into tables to more advanced criteria that test the formulation of complex integrity constraints such as multi-column PRIMARY KEYs and arbitrary CHECK constraints. Due to different vendor interpretations of the structured query language (SQL) specification with regard to how integrity constraints should actually function in practice, our criteria crucially account for the underlying semantics of the database management system (DBMS). After formally defining these coverage criteria and relating them in a subsumption hierarchy, we present two approaches for automatically generating tests that satisfy the criteria. We then describe the results of an empirical study that uses mutation analysis to investigate the fault-finding capability of data generated when our coverage criteria are applied to a wide variety of relational schemas hosted by three well-known and representative DBMSs—HyperSQL, PostgreSQL, and SQLite. In addition to revealing the complementary fault-finding capabilities of the presented criteria, the results show that mutation scores range from as low as just 12% of mutants being killed with the simplest of criteria to 96% with the most advanced
Empirically evaluating flaky test detection techniques combining test case rerunning and machine learning models
No full textA flaky test is a test case whose outcome changes without modification to the code of the test case or the program under test. These tests disrupt continuous integration, cause a loss of developer productivity, and limit the efficiency of testing. Many flaky test detection techniques are rerunning-based, meaning they require repeated test case executions at a considerable time cost, or are machine learning-based, and thus they are fast but offer only an approximate solution with variable detection performance. These two extremes leave developers with a stark choice. This paper introduces CANNIER, an approach for reducing the time cost of rerunning-based detection techniques by combining them with machine learning models. The empirical evaluation involving 89,668 test cases from 30 Python projects demonstrates that CANNIER can reduce the time cost of existing rerunning-based techniques by an order of magnitude while maintaining a detection performance that is significantly better than machine learning models alone. Furthermore, the comprehensive study extends existing work on machine learning-based detection and reveals a number of additional findings, including (1) the performance of machine learning models for detecting polluter test cases; (2) using the mean values of dynamic test case features from repeated measurements can slightly improve the detection performance of machine learning models; and (3) correlations between various test case features and the probability of the test case being flaky
Automatically identifying potential regressions in the layout of responsive web pages
No full textProviding a good user experience on the ever-increasing number and variety of devices being used to browse the web is a difficult, yet critical, task. With Responsive Web Design (RWD), front-end web developers design web pages so that they dynamically resize and rearrange content to best fit the dimensions of a device’s screen. However, when making code modifications to a responsive page, developers can easily introduce regressions from the correct layout that have detrimental effects at unpredictable screen sizes.
For instance, the source code change that a developer makes to improve the layout at one screen size may obscure a page’s content at other sizes. Current approaches to testing are often insufficient because they rely on limited tools and error-prone manual inspections of a web page. As such, many unintended regressions in web page layout often go undetected and ultimately manifest in production web sites. To address the challenge of detecting regressions in responsive web pages, this paper presents an automated approach that extracts the responsive layout of two versions of a page and compares them, alerting developers to the differences in layout that they may wish to investigate further. We implemented the approach and
empirically evaluated it on 15 real-world responsive web pages. Leveraging code mutations that a tool automatically injected into the pages as a systematic simulation of developer changes, the experiments show that the approach was highly effective. When compared with manual and automated baseline testing techniques, it detected 12.5% and 18.75% more injected changes, respectively. Along with identifying the best parameters for the method that extracts the responsive layout, the experiments show that the approach surpasses the baselines across changes that vary in their impact, but works particularly well for subtle, hard-to-detect mutants, showing the benefits of automatically identifying regressions in web page layout
The synthesis of monodisperse alkanes with long chains
No full textThis thesis discusses reasons for the interest in monodisperse long chain alkanes and describes attempts, past and present, to synthesise such molecules. Chapter 1 discusses why the synthesis of such molecules are important and the objectives of this project. Chapter 2 reviews the methods previous groups have devised to prepare pure samples of long chain alkanes. In particular, work carried out by Whiting et al. at Bristol, whose scheme formed the basis of the early work in Durham. Chapter 3 describes the work in Durham and improvements which were made to Whiting's method, allowing the synthesis of longer chain lengths and greater quantities of materials to be achieved. Chapter 4 provides a summary of the practical work carried out by the author. Chapter 5 gives experimental details of the work described in Chapter 4
Mechanisms and consequences of reduced dendritic growth of cerebellar Purkinje cells
No full textThe cerebellum is a brain region crucial for coordination and motor learning. Being the principal output cell of the cerebellar cortex, Purkinje cell loss and degeneration play an important role in many cerebellar diseases. The most striking feature of cerebellar Purkinje cells is their large and extensively branched dendritic tree, which is almost flat and strictly arranged in the sagittal plane. The factors and molecules which control the growth and patterning of neuronal dendrites are still poorly understood. Previous research in our lab has shown that chronic activation of metabotropic glutamate receptor 1 (mGluR1) (Sirzen-Zelenskaya et al., 2006) or Protein Kinase C (PKC) (Metzger & Kapfhammer, 2000; Schrenk et al., 2002) in organotypic cerebellar slice cultures of postnatal mice severely inhibits the growth and development of the Purkinje cell dendritic tree.
Although we found that the similar effect induced by mGluR1 or PKC is mediated by independent mechanisms (Sirzen-Zelenskaya et al., 2006), the signaling events leading to inhibition of dendritic growth after both mGluR1 and PKC activation remain largely unknown. Another intriguing question is that of the physiological relevance of limiting dendritic size after chronic activation of a metabotropic glutamate receptor.
We addressed both aspects using organotypic cerebellar slice cultures. In this culture model, a 300 µm thick slice of cerebellar tissue is kept in culture, where the natural microenvironment of a cell with neighboring cell-cell interactions and local neuronal networks are preserved. In order to study Purkinje cell dendritic development, cerebella from mice were cultured shortly before Purkinje cells enter the developmental stage of rapid dendritic growth and expansion, and were maintained for 10-12 days.
Purkinje cells are especially affected in various diseases involving excitotoxicity. We have tested the hypothesis that it is the size of the dendritic tree which determines Purkinje cell sensitivity to excitatory overload. Therefore, we have grown Purkinje cells under conditions which result in a strong reduction of dendritic tree size. Then we have exposed the cultures to (RS)-a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), which is an appropriate model system to study excitotoxic neurodegeneration in the cerebellum as it selectively kills Purkinje cells but leaves cerebellar granule cells unharmed. Our results indicate that a reduction of the size of the dendritic tree in Purkinje cells does not offer any protection from glutamate-induced excitotoxicity. Staining for the vesicular glutamate transporter vGluT1 revealed a high density of glutamatergic synapses on the stunted dendritic trees of pre-treated Purkinje cells. This suggests that receptor density rather than total receptor load is important for determining the sensitivity of Purkinje cells to AMPA-mediated neurotoxicity.
In a second study we have searched for potential mechanisms limiting Purkinje cell dendritic growth and have concentrated on channels allowing the entry of Ca2+ ions, especially the TRPC3, P/Q-type and T-type Ca2+ channels.
To analyze the roles of these channels in mediating dendritic reduction induced by mGluR1 or PKC we have treated Purkinje cells in cerebellar slice cultures with the mGluR1 activator DHPG or the PKC activator PMA and simultaneously with different combinations of Ca2+ channel inhibitors. After the culture period, the size of the dendritic trees was evaluated.
Co-treatment with a combination of P/Q- and T-type inhibitors partially rescued the dendrite-reducing effects induced by DHPG or PMA treatment. In contrast, no improvement of dendritic growth was found in mice lacking TRPC3 function or using an acute pharmacological TRPC3 inhibitor. Furthermore, the partial rescue obtained by P/Q- and T-type inhibition was not further increased by additional co-treatments with inhibitors of GluRδ2 - or R-type Ca2+ channels, or of Ca2+ release from internal stores.
In conclusion, our results suggest that T-type and P/Q-type Ca2+ channels are part of the signaling pathways induced after chronic mGluR1 and PKC stimulation resulting in the inhibition of dendritic growth, while no involvement of TPRC3-, GluRδ2-, R-type Ca2+ channels or Ca2+ release from intracellular stores was found
Towards the Theatre: Opasnyi Povorot (Dangerous Corner). The 1939 Production by G.M. Kozintsev at the Leningrad Comedy Theater
No full textThe subject of this research is the first production in a series of theatrical works by G.M. Kozintsev (1905–1973) of the late 1930s — early 1950s, which are fundamentally important both in his creative biography and in the history of Soviet theatre of that era. The author suggests that the entry of the famous film director into theatre was caused by the desire to find a way out of a creative impasse.
The director’s appeal to the play of the modern English novelist and playwright J.B. Priestley and its controversial interpretation were driven by the dramatic atmosphere of the late 1930s. The eccentric grotesque of the play and its pamphlet character, which was insisted on by the director, are considered as a parody of tragedy by the author of the research. This reveals a fundamental connection between the production under consideration and the subsequent successful experiments of G.M. Kozintsev in the field of theatrical Shakespeareana. The article draws attention to the fundamental connection between the style of the production and the general style of the Leningrad State Comedy Theatre developed by its director — the outstanding theatre director and set designer, G.M. Kozintsev and E.L. Schwartz’s friend and associate, N.P. Akimov. The research is based on the performance reviews, testimonies of the participants of the performance, contemporaries close to the director (especially the playwright and screenwriter E.L. Schwartz and the long-term G.M. Kozintsev’s co-author L.Z. Trauberg), as well as the surviving radio version of the play
Stevin Outlet Sluices: Wave impact under a beam
No full textThe Dutch department of Public Works had a problem regarding wave impacts on a beam in the Stevin outlet sluices, located in the Afsluitdijk. Wave impacts on this beam could also cause a peak pressure on the barrier gate, just behind the beam. The numerical program ComFLOW and physical scale experiments were used to predict the wave impacts for different hydraulic conditions (i.e. wave height, wave period and water level). The research questions were: 1. How is the wave load on the northern gates depending on the presence of the military beam? 2. How large is a wave impact load on the bottom of the military beam in the Stevin outlet sluices? 3. How well can the numerical model ComFLOW and physical modelling be used to determine the wave impact on the bottom of the military beam in the Stevin outlet sluices? 2D scaled experiments were performed making use of a model with the (simplified) geometry of the Stevin outlet sluices and regular waves. It was found that the largest wave impacts occurred for water levels equal to the bottom plane of the beam or slightly under it. This happened for the shortest waves in the test domain. The largest pressure measured on the beam was approximately 50 kPa or 35H, with H representing the incident wave height in front of the model. It was also found that the spread in the peak pressures for one single experiment was large. The results of the measured impulse per peak showed far less spread. The effect of wave impacts under the beam was also found on the vertical wall under the beam. The actual pressures however were less and they were decreasing with increasing depth. Besides physical wave impact testing, a few experiments were performed with the beam removed from the model. This resulted in wave simply running up the vertical wall of the model. They did not cause a wave impact. The measurements of both type of experiments, with and without a beam, were compared. This revealed that the total wave impulse on the gate was not affected by the presence of the beam. However the distribution of the pressure within a single wave period was significantly different. In case of a beam, a large impact peak was observed, whereas the other wave only showed a small hump caused by the deflected flow against the vertical wall. When the calculated and measured wave impact results were compared it became clear that ComFLOW underestimated the peak pressures by a factor 2 to 20 for the pressures on the impact plane. The same was done for the peak impulse. This showed that the impulse of the peak on the impact plane were underestimated by a factor 2 at most. These results confirmed that the used grid was too coarse for the program to model the physics correctly. The main conclusions to the research questions were: 1. The presence of the military beam causes a different distribution of the force on the gate within a wave period. The total amount of impulse is more or less the same as for the situation without a beam. With the military beam, a wave impact results in a peak force on the gate. Without the beam, there will be no peak force. 2. The largest measured wave impact pressure is 35H. 3. Both ComFLOW and physical modelling can be used to predict wave impacts for the geometry of Stevin outlet sluices. Much care should be taken when modelling and much attention should go to the input parameters of the program.Hydraulic StructuresHydraulic EngineeringCivil Engineering and Geoscience
A Professional Author-How G.M. Glaskin Earned a Living
No full textWestern Australian author Gerald Marcus Glaskin (GMG; 16 December 1923-11 March 2000) wrote from life, using his experiences to continually expand his creative repertoire. In one sense, this was to be his downfall, as his life was unconventional for his time. Because he mined own experiences so much in his creative writing, his works eventually moved out of mainstream markets. However, this paper focuses on his financial success as a writer, details of which can be documented through study of the meticulous records kept by both GMG and his publisher, Barrie & Rockliff of London. Other scholarly analysis of the income received by authors is limited. Katherine Bode (2012) does not deal with the subject in her otherwise comprehensive quantitative analysis of Australian publishing. What little is known about the income of professional authors from this or other periods, and whether they were able to survive on the proceeds of their writing, is incidental to other research
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