Do software models based on the UML aid in source-code comprehensibility? Aggregating evidence from 12 controlled experiments

In this paper, we present the results of long-term research conducted in order to study the contribution made by software models based on the Unified Modeling Language (UML) to the comprehensibility of Java source-code deprived of comments. We have conducted 12 controlled experiments in different experimental contexts and on different sites with participants with different levels of expertise (i.e., Bachelor’s, Master’s, and PhD students and software practitioners from Italy and Spain). A total of 333 observations were obtained from these experiments. The UML models in our experiments were those produced in the analysis and design phases. The models produced in the analysis phase were created with the objective of abstracting the environment in which the software will work (i.e., the problem domain), while those produced in the design phase were created with the goal of abstracting implementation aspects of the software (i.e., the solution/application domain). Source-code comprehensibility was assessed with regard to correctness of understanding, time taken to accomplish the comprehension tasks, and efficiency as regards accomplishing those tasks. In order to study the global effect of UML models on source-code comprehensibility, we aggregated results from the individual experiments using a meta-analysis. We made every effort to account for the heterogeneity of our experiments when aggregating the results obtained from them. The overall results suggest that the use of UML models affects the comprehensibility of source-code, when it is deprived of comments. Indeed, models produced in the analysis phase might reduce source-code comprehensibility, while increasing the time taken to complete comprehension tasks. That is, browsing source code and this kind of models together negatively impacts on the time taken to complete comprehension tasks without having a positive effect on the comprehensibility of source code. One plausible justification for this is that the UML models produced in the analysis phase focus on the problem domain. That is, models produced in the analysis phase say nothing about source code and there should be no expectation that they would, in any way, be beneficial to comprehensibility. On the other hand, UML models produced in the design phase improve source-code comprehensibility. One possible justification for this result is that models produced in the design phase are more focused on implementation details. Therefore, although the participants had more material to read and browse, this additional effort was paid back in the form of an improved comprehension of source code.     

New perspectives on the clinical applications of functional radiology of the liver

Preliminary results of "new clinical applications" of functional imaging of the liver are reported. In 20 healthy volunteers portal flow measurement with Doppler US at the level of right, left portal branch and main portal trunk, showed the preferential distribution in baseline conditions of portal flow to the right liver (about 68%) as compared to the left portal branch. This influenced MRI volumetry of right liver as compared to left liver. After meal intake, flow increase was significantly higher at the level of left portal branch suggestive for a "functional reserve" in left liver. Portal flow physiology was examined in preparation of portal imaging before and after portal vein embolization, a procedure performed preoperatively before enlarged hepatectomies.     

Gonadotropin-releasing hormone agonists administration in polycystic ovary syndrome. Effects on bone mass

Women with amenorrhea and polycystic ovaries (PCO) seem to present a relative degree of protection against bone loss caused by hypoestrogenism. We treated 20 patients affected by polycystic ovary syndrome (PCOS) with a gonadotropin-releasing hormone agonist (GnRH-a) for 6 months. After treatment mean bone mineral density (BMD) significantly decreased. We concluded that patients with PCOS have to be considered at risk of developing osteopenia when treated with GnRH-a. The relative protection against osteoporosis, that is present in amenorrheic patients with PCO, might be attributed to the characteristics of amenorrhea in these patients.     

Experimental examination of the effects of televised motor vehicle commercials on risk-positive attitudes,emotions and risky driving inclinations

Purpose

This study examined the short-term effects of risky driving motor vehicle television commercials on risk-positive attitudes, emotions and risky driving inclinations in video-simulated critical road traffic situations among males and females, within an experimental design.

Method

Participants were randomly assigned to one of three televised commercial advertising conditions embedded in a television show: a risky driving motor vehicle commercial condition, a non-risky driving motor vehicle commercial condition and a control non-motor vehicle commercial condition. Participants subsequently completed the Implicit Attitude Test (IAT) to measure risk-positive attitudes, Driver Thrill Seeking Scale (DTSS) to measure risk-positive emotions and the Vienna Risk-Taking Test – Traffic (WRBTV) to measure risky driving inclinations.

Results

ANOVA analyses indicated that type of commercial participants watched did not affect their performance on the IAT, DTSS or WRBTV. However, a main effect of heightened risk-positive emotions and risky driving inclinations was found for males.

Discussion

Despite public and governmental concern that risky driving motor vehicle commercials may increase the likelihood that people exposed to these commercials engage in risky driving, this experimental study found no immediate effect of brief exposure to a risky driving motor vehicle commercial on risk-positive attitudes, emotions or risky driving inclinations. Subsequent research should examine the effects of cumulative exposure to risky driving motor vehicle television commercials and print advertisements.     

Pyogenic liver abscesses: 13 years of experience in percutaneous needle aspiration with US guidance

PURPOSE: To determine the efficacy of percutaneous needle aspiration (PNA) with antibiotic therapy in treatment for pyogenic liver abscess (PLA). MATERIALS AND METHODS: One hundred fifteen patients (59 male; 56 female; age range, 16-86 years; mean age, 45.3 years) with 147 PLAs (mean diameter, 6.8 cm; range, 3-16 cm) underwent PNA with ultrasound (US) guidance and antibiotic therapy. Needle caliber (22-16 gauge) was tailored to PLA volume. If necessary, PNA was repeated every 3-7 days. RESULTS: Three hundred one PNAs were performed (range, 1-4 per patient; mean, 2.2 per patient). A single puncture was sufficient in 57 patients. Cure (normalization of clinical and laboratory parameters and resolution of hepatic lesions) was achieved in 113 patients (98.3%). Two patients with large PLAs required surgery. Patients were hospitalized 7-24 days (mean, 9 days). In the last eight patients, all abscesses were evacuated in one session. Neither complications nor deaths ensued. Recurrence of PLA was not observed in any patient during follow-up (6-36 months). CONCLUSION: US-guided PNA with antibiotic therapy in treatment for PLA is a valid alternative to prolonged catheter drainage.     

Theory for optimal design of waveguiding light concentrators in photovoltaic microcell arrays

Efficiency of ultrathin flexible solar photovoltaic silicon microcell arrays can be significantly improved using nonimaging solar concentrators. A fluorophore is introduced to match the solar spectrum and the low-reflectivity wavelength range of Si, reduce the escape losses, and allow the nontracking operation. In this paper we optimize our solar concentrators using a luminescent/nonluminescent photon transport model. Key modeling results are compared quantitatively to experiments and are in good agreement with the latter. Our solar concentrator performance is not limited by the dye self-absorption. Bending deformations of the flexible solar collectors do not result in their indirect gain degradation compared to flat solar concentrators with the same projected area.