Analyzing impact of experience curve on ROI in the software product line adoption process

Cataloged from PDF version of article.Context: Experience curve is a well-known concept in management and education science, which explains the phenomenon of increased worker efficiency with repetitive production of a good or service. Objective: We aim to analyze the impact of the experience curve effect on the Return on Investment (ROI) in the software product line engineering (SPLE) process. Method: We first present the results of a systematic literature review (SLR) to explicitly depict the studies that have considered the impact of experience curve effect on software development in general. Subsequently, based on the results of the SLR, the experience curve effect models in the literature, and the SPLE cost models, we define an approach for extending the cost models with the experience curve effect. Finally, we discuss the application of the refined cost models in a real industrial context. Results: The SLR resulted in 15 primary studies which confirm the impact of experience curve effect on software development in general but the experience curve effect in the adoption of SPLE got less attention. The analytical discussion of the cost models and the application of the refined SPLE cost models in the industrial context showed a clear impact of the experience curve effect on the time-to-market, cost of development and ROI in the SPLE adoption process. Conclusions: The proposed analysis with the newly defined cost models for SPLE adoption provides a more precise analysis tool for the management, and as such helps to support a better decision making. © 2014 Elsevier B.V. All rights reserved

Size Segregation of Granular Matter in Silo Discharges

We present an experimental study of segregation of granular matter in a quasi-two dimensional silo emptying out of an orifice. Size separation is observed when multi-sized particles are used with the larger particles found in the center of the silo in the region of fastest flow. We use imaging to study the flow inside the silo and quantitatively measure the concentration profiles of bi-disperse beads as a function of position and time. The angle of the surface is given by the angle of repose of the particles, and the flow occurs in a few layers only near the top of this inclined surface. The flowing region becomes deeper near the center of the silo and is confined to a parabolic region centered at the orifice which is approximately described by the kinematic model. The experimental evidence suggests that the segregation occurs on the surface and not in the flow deep inside the silo where velocity gradients also are present. We report the time development of the concentrations of the bi-disperse particles as a function of size ratios, flow rate, and the ratio of initial mixture. The qualitative aspects of the observed phenomena may be explained by a void filling model of segregation.Comment: 6 pages, 10 figures (gif format), postscript version at http://physics.clarku.edu/~akudrolli/nls.htm

Ground truth deficiencies in software engineering: when codifying the past can be counterproductive

Many software engineering tools build and evaluate their models based on historical data to support development and process decisions. These models help us answer numerous interesting questions, but have their own caveats. In a real-life setting, the objective function of human decision-makers for a given task might be influenced by a whole host of factors that stem from their cognitive biases, subverting the ideal objective function required for an optimally functioning system. Relying on this data as ground truth may give rise to systems that end up automating software engineering decisions by mimicking past sub-optimal behaviour. We illustrate this phenomenon and suggest mitigation strategies to raise awareness

Dissipation and fluctuations in nanoelectromechanical systems based on carbon nanotubes

Tribological characteristics of nanotube-based nanoelectromechanical systems (NEMS) exemplified by a gigahertz oscillator are studied. Various factors that influence the tribological properties of the nanotube-based NEMS are quantitatively analyzed with the use of molecular dynamics calculations of the quality factor (Q-factor) of the gigahertz oscillator. We demonstrate that commensurability of the nanotube walls can increase the dissipation rate, while the structure of the wall ends and the nanotube length do not influence the Q-factor. It is shown that the dissipation rate depends on the interwall distance and the way of fixation of the outer wall and is significant in the case of a poor fixation for the nanotubes with a large interwall distance. Defects are found to strongly decrease the Q-factor due to the excitation of low-frequency vibrational modes. No universal correlation between the static friction forces and the energy dissipation rate is established. We propose an explanation of the obtained results on the basis of the classical theory of vibrational-translational relaxation. Significant thermodynamics fluctuations are revealed in the gigahertz oscillator by molecular dynamics simulations and analyzed in the framework of the fluctuation-dissipation theorem. Possibility of designing the NEMS with a desirable Q-factor and their applications are discussed on the basis of the above results.Comment: 32 pages, 7 figure

Mitochondrial carrier homolog 1 (Mtch1) antibodies in neuro-Behçet's disease

Cataloged from PDF version of article.Efforts for the identification of diagnostic autoantibodies for neuro-Behcet's disease (NBD) have failed. Screening of NBD patients' sera with protein macroarray identified mitochondrial carrier homolog 1 (Mtch1), an apoptosis-related protein, as a potential autoantigen. ELISA studies showed serum Mtch1 antibodies in 68 of 144 BD patients with or without neurological involvement and in 4 of 168 controls corresponding to a sensitivity of 47.2% and specificity of 97.6%. Mtch1 antibody positive NBD patients had more attacks, increased disability and lower serum nucleosome levels. Mtch1 antibody might be involved in pathogenic mechanisms of NBD rather than being a coincidental byproduct of autoinflammation. © 2013 Elsevier B.V

Friction phenomena and their impact on the shear behaviour of granular material

In the discrete element simulation of granular materials, the modelling of contacts is crucial for the prediction of the macroscopic material behaviour. From the tribological point of view, friction at contacts needs to be modelled carefully, as it depends on several factors, e.g. contact normal load or temperature to name only two. In discrete element method (DEM) simulations the usage of Coulomb’s law of friction is state of the art in modelling particle–particle contacts. Usually in Coulomb’s law, for all contacts only one constant coefficient of friction is used, which needs to reflect all tribological effects. Thus, whenever one of the influence factors of friction varies over a wide range, it can be expected that the usage of only one constant coefficient of friction in Coulomb’s law is an oversimplification of reality. For certain materials, e.g. steel, it is known that a dependency of the coefficient of friction on the contact normal load exists. A more tribological tangential contact law is implemented in DEM, where the interparticle friction coefficient depends on the averaged normal stress in the contact. Simulations of direct shear tests are conducted, using steel spheres of different size distributions. The strong influence of interparticle friction on the bulk friction is shown via a variation of the constant interparticle friction coefficient. Simulations with constant and stress-dependent interparticle friction are compared. For the stress-dependent interparticle friction, a normal stress dependency of the bulk friction is seen. In the literature, measurements of different granular materials and small normal loads also show a stress dependency of the bulk friction coefficient. With increasing applied normal stress, the bulk friction coefficient reduces both in the experiments and in the simulations

Atypical presentation of colon adenocarcinoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Adenocarcinoma of the colon is the most common histopathological type of colorectal cancer. In Western Europe and the United States, it is the third most common type and accounts for 98% of cancers of the large intestine. In Uganda, as elsewhere in Africa, the majority of patients are elderly (at least 60 years old). However, more recently, it has been observed that younger patients (less than 40 years of age) are presenting with the disease. There is also an increase in its incidence and most patients present late, possibly because of the lack of a comprehensive national screening and preventive health-care program. We describe the clinicopathological features of colorectal carcinoma in the case of a young man in Kampala, Uganda.</p> <p>Case presentation</p> <p>A 27-year-old man from Kampala, Uganda, presented with gross abdominal distension, progressive loss of weight, and fever. He was initially screened for tuberculosis, hepatitis, and lymphoma, and human immunodeficiency virus/acquired immunodeficiency syndrome infection. After a battery of tests, a diagnosis of colorectal carcinoma was finally established with hematoxylin and eosin staining of a cell block made from the sediment of a liter of cytospun ascitic fluid, which showed atypical glands floating in abundant extracellular mucin, suggestive of adenocarcinoma. Ancillary tests with alcian blue/periodic acid Schiff and mucicarmine staining revealed that it was a mucinous adenocarcinoma. Immunohistochemistry showed strong positivity with CDX2, confirming that the origin of the tumor was the colon.</p> <p>Conclusions</p> <p>Colorectal carcinoma has been noted to occur with increasing frequency in young adults in Africa. Most patients have mucinous adenocarcinoma, present late, and have rapid disease progression and poor outcome. Therefore, colorectal malignancy should no longer be excluded from consideration only on the basis of a patient's age. A high index of suspicion is important in the diagnosis of colorectal malignancy in young African patients.</p

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016.

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

A fast and accurate method to detect allelic genomic imbalances underlying mosaic rearrangements using SNP array data

<p>Abstract</p> <p>Background</p> <p>Mosaicism for copy number and copy neutral chromosomal rearrangements has been recently identified as a relatively common source of genetic variation in the normal population. However its prevalence is poorly defined since it has been only studied systematically in one large-scale study and by using non optimal <it>ad-hoc </it>SNP array data analysis tools, uncovering rather large alterations (> 1 Mb) and affecting a high proportion of cells. Here we propose a novel methodology, Mosaic Alteration Detection-MAD, by providing a software tool that is effective for capturing previously described alterations as wells as new variants that are smaller in size and/or affecting a low percentage of cells.</p> <p>Results</p> <p>The developed method identified all previously known mosaic abnormalities reported in SNP array data obtained from controls, bladder cancer and HapMap individuals. In addition MAD tool was able to detect new mosaic variants not reported before that were smaller in size and with lower percentage of cells affected. The performance of the tool was analysed by studying simulated data for different scenarios. Our method showed high sensitivity and specificity for all assessed scenarios.</p> <p>Conclusions</p> <p>The tool presented here has the ability to identify mosaic abnormalities with high sensitivity and specificity. Our results confirm the lack of sensitivity of former methods by identifying new mosaic variants not reported in previously utilised datasets. Our work suggests that the prevalence of mosaic alterations could be higher than initially thought. The use of appropriate SNP array data analysis methods would help in defining the human genome mosaic map.</p

A Survey of Genomic Traces Reveals a Common Sequencing Error, RNA Editing, and DNA Editing

While it is widely held that an organism's genomic information should remain constant, several protein families are known to modify it. Members of the AID/APOBEC protein family can deaminate DNA. Similarly, members of the ADAR family can deaminate RNA. Characterizing the scope of these events is challenging. Here we use large genomic data sets, such as the two billion sequences in the NCBI Trace Archive, to look for clusters of mismatches of the same type, which are a hallmark of editing events caused by APOBEC3 and ADAR. We align 603,249,815 traces from the NCBI trace archive to their reference genomes. In clusters of mismatches of increasing size, at least one systematic sequencing error dominates the results (G-to-A). It is still present in mismatches with 99% accuracy and only vanishes in mismatches at 99.99% accuracy or higher. The error appears to have entered into about 1% of the HapMap, possibly affecting other users that rely on this resource. Further investigation, using stringent quality thresholds, uncovers thousands of mismatch clusters with no apparent defects in their chromatograms. These traces provide the first reported candidates of endogenous DNA editing in human, further elucidating RNA editing in human and mouse and also revealing, for the first time, extensive RNA editing in Xenopus tropicalis. We show that the NCBI Trace Archive provides a valuable resource for the investigation of the phenomena of DNA and RNA editing, as well as setting the stage for a comprehensive mapping of editing events in large-scale genomic datasets