Can observational techniques help novices overcome the software inspection learning curve? An empirical investigation

When learning a new software engineering technique, there is a learning curve that must be overcome. In particular, when studies are conducted in a classroom setting, researchers need a method for quickly accelerating the experience of novice subjects to allow the results to be more applicable in industrial settings. In this paper, we propose and test a method to enable novices to gain process experience to allow them to more quickly overcome the learning curve. The method we evaluate allows an inspector to gain experience with the inspection process by observing an inspection performed by someone else. The results of the study show that the proposed method for gaining experience appears to be useful in some limited cases, that is, for low experienced subjects who were inspecting a requirements document from a domain in which they had low knowledge. Based on the results of this study, we are able to propose some new related hypotheses to be tested in future studies.     

Worst case product performance verification with electromagnetic interference test applications

When many variables are prevalent, it is difficult systematically to identify the optimum configuration for product certification. This need can occur in areas such as testing performance of closed-loop servo systems and testing products for electromagnetic interference (EMI). This paper proposes a test strategy to identify a 'determined worst case expected' product configuration and a criterion for pass/fail. The process was developed originally for EMI test applications; however, it can also be useful for other product performance specifications.     

Performance of In0.53Ga0.47As and InPjunction field-effect transistors for optoelectronic integratedcircuits. II. Optical receiver analysis

For pt.I see ibid., p.957-65. The receiver under study consists of an In_0.53Ga_0.47As p-i-n photodiode and an In_0.53Ga_0.47As or InP JFET transimpedance preamplifier. For this study, the two-region JFET model developed in pt.I is extended to include the dependence of receiver noise on transistor design. The authors find that the channel doping should be small enough to avoid shot noise due to the onset of tunneling current between the gate and drain, where as it must be large enough to provide adequate gain. Also, they show that the receiver sensitivity is not a strong function of input FET gate width. Hence, for circuits with high device density, the gate width and the FET power dissipation can be an order of magnitude less than for those structures currently investigated, thereby incurring a sensitivity penalty of only 1 dB as against wide-gate transistors. Optimized receivers using either InP or In_0.53Ga_0.47As JFETs are found to have comparable sensitivities     

Neural network models

The remarkable processing capabilities of the nervous system must derive at least in part from the large numbers of neurons participating (roughly 10¹⁰), since the timescales involved are of the order of milliseconds, rather than the nanoseconds of modern computers. We summarise common features of the neural network models which attempt to capture this behaviour and describe the many levels of parallelism which they exhibit. A range of models has been implemented on the SIMD (ICL Distributed Array Processor) and MIMD (Meiko Computing Surface) hardware at Edinburgh. Examples include: (i) training algorithms in the context of the Hopfield net, with specific application to the storage of words and text with content-addressable memory; (ii) the back-propagation training algorithm for the multi-layer perception; (iii) image restoration with Hopfield and Tank analogue neurons, and (iv) the Durbin and Willshaw elastic net, as applied to the travelling salesman problem.     

Low-threshold, high-power, 1.3-μm wavelength, InGaAsP-InPetched-facet folded-cavity surface-emitting lasers

A 1.3-μm wavelength, InGaAsP-InP folded-cavity, surface-emitting laser with CH₄-H₂ reactive ion-etched vertical and 45° angled facets was demonstrated for the first time. Continuous-wave threshold currents of 32 mA have been achieved, with >15 mW CW power for the surface-emitted light. These surface-emitting lasers with two dry-etched facets are suitable for wafer-level testing and for monolithic integration with other InP-based photonic devices     

An experimental low-loss single-wavelength bidirectional lightwave link

We describe the perofrmance of a low-loss couplerless bi-directional transmission experiment which operates at a single wavelength. The system is unique in that it employs an annular In0.53Ga0.47As/InP photodetector and has potential for use for both long-wavelength (lambda < 1.7 mum) and short-wavelength (lambda geq 0.82mum) transmission. We find that the optical crosstalk between the near-end transmitter and receiver is as low as -16.6 dB (-33.2 dB electrical) for a 200-m link: a value acceptable for use in many short haul system applications.     

Weight-based heparin dosing: clinical response and resource utilization

The objective of this study was to assess a weight-based heparin (WBH) nomogram (80-U/kg bolus, 18-U/kg-per-hour initial infusion) and determine its clinical performance and impact on resource utilization. All patients treated with heparin for venous thromboembolism or unstable angina during a 15-week study period were included in this retrospective, chart-review study. Three groups were identified: patients treated with WBH, patients whose regimen deviated from the weight-based nomogram (DEV), and matched historical controls (HCs). In patients receiving heparin for more than 24 hours, those treated with WBH achieved threshold activated partial thromboplastin time (aPTT) levels significantly faster than did HC or DEV patients. However, 42% of WBH-treated patients were found to have initial supratherapeutic responses. Logistic regression analysis identified age > or =67 years, prior warfarin therapy within 7 days of heparin, and high initial infusion rate as predictive of a supratherapeutic aPTT response; smoking was predictive of a subtherapeutic response. Bleeding events were not significantly different between groups. An infusion rate of 15 U/kg per hour was found to closely approximate our population's actual heparin infusion requirement. Resource utilization was significantly different between the WBH and HC groups in terms of nursing interventions at 48 to 72 hours. We concluded that WBH rapidly drives patients' aPTT response above the therapeutic threshold for heparin; however, prudent adjustment of the initial infusion rate is necessary to avoid a supratherapeutic aPTT response. Our data support a nomogram with an initial infusion rate of 15 U/kg per hour.     

Screening older adults for depression in primary care settings.

Primary care is a logical environment for depression recognition in older adults. Most older adults are diagnosed and treated for depression by primary care providers. Recognition systems for depression in this setting are particularly needed because the prevalence of depression in older primary care patients may range from 7% to 36%, depending on the instrument and diagnostic criteria used. Implementing systematic detection systems in primary care settings has proven difficult. In one study, only one third of all physicians surveyed used any formal screening tool. Though a number of barriers to recognition of depression have been identified, the authors focus their discussion in this article on two, time and patient factors, and review two screening instruments, the Geriatric Depression Scale--Short Form and the Center for Epidemiologic Studies Depression Scale, that may be able to address these factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Software mutational robustness

Neutral landscapes and mutational robustness are believed to be important enablers of evolvability in biology. We apply these concepts to software, defining mutational robustness to be the fraction of random mutations to program code that leave a program’s behavior unchanged. Test cases are used to measure program behavior and mutation operators are taken from earlier work on genetic programming. Although software is often viewed as brittle, with small changes leading to catastrophic changes in behavior, our results show surprising robustness in the face of random software mutations. The paper describes empirical studies of the mutational robustness of 22 programs, including 14 production software projects, the Siemens benchmarks, and four specially constructed programs. We find that over 30 % of random mutations are neutral with respect to their test suite. The results hold across all classes of programs, for mutations at both the source code and assembly instruction levels, across various programming languages, and bear only a limited relation to test suite coverage. We conclude that mutational robustness is an inherent property of software, and that neutral variants (i.e., those that pass the test suite) often fulfill the program’s original purpose or specification. Based on these results, we conjecture that neutral mutations can be leveraged as a mechanism for generating software diversity. We demonstrate this idea by generating a population of neutral program variants and showing that the variants automatically repair latent bugs. Neutral landscapes also provide a partial explanation for recent results that use evolutionary computation to automatically repair software bugs.