A Comparison of Three Modes of Collaboration for Software Development

In the current environment of global collaboration, multiple models for collaborative ventures have been introduced. We consider traditional, contractual interactions as well as three modes of collaboration—supply-chain management, a standard virtual organization, and inter-organizational collaborative software development (ICSD). After outlining multiple characteristics of these modes, and their strengths and weaknesses, we examine how to select an approach for a software project, and characterize non-software-development applications for which an ICSD approach may be appropriate. Each of these can then be used as input in selecting an optimal mode and practices for the project

Comparison of Diffusion-Weighted MRI Reconstruction Methods for Visualization of Cranial Nerves in Posterior Fossa Surgery

Diffusion-weighted imaging (DWI)-based tractography has gained increasing popularity as a method for detailed visualization of white matter (WM) tracts. Different imaging techniques, and more novel, advanced imaging methods provide significant WM structural detail. While there has been greater focus on improving tract visualization for larger WM pathways, the relative value of each method for cranial nerve reconstruction and how this methodology can assist surgical decision-making is still understudied. Images from 10 patients with posterior fossa tumors (4 male, mean age: 63.5), affecting either the trigeminal nerve (CN V) or the facial/vestibular complex (CN VII/VIII), were employed. Three distinct reconstruction methods [two tensor-based methods: single diffusion tensor tractography (SDT) (3D Slicer), eXtended streamline tractography (XST), and one fiber orientation distribution (FOD)-based method: streamline tractography using constrained spherical deconvolution (CSD)-derived estimates (MRtrix3)], were compared to determine which of these was best suited for use in a neurosurgical setting in terms of processing speed, anatomical accuracy, and accurate depiction of the relationship between the tumor and affected CN. Computation of the tensor map was faster when compared to the implementation of CSD to provide estimates of FOD. Both XST and CSD-based reconstruction methods tended to give more detailed representations of the projections of CN V and CN VII/VIII compared to SDT. These reconstruction methods were able to more accurately delineate the course of CN V and CN VII/VIII, differentiate CN V from the cerebellar peduncle, and delineate compression of CN VII/VIII in situations where SDT could not. However, CSD-based reconstruction methods tended to generate more invalid streamlines. XST offers the best combination of anatomical accuracy and speed of reconstruction of cranial nerves within this patient population. Given the possible anatomical limitations of single tensor models, supplementation with more advanced tensor-based reconstruction methods might be beneficial

The Sorghum bicolor reference genome: improved assembly, gene annotations, a transcriptome atlas, and signatures of genome organization.

Sorghum bicolor is a drought tolerant C4 grass used for the production of grain, forage, sugar, and lignocellulosic biomass and a genetic model for C4 grasses due to its relatively small genome (approximately 800 Mbp), diploid genetics, diverse germplasm, and colinearity with other C4 grass genomes. In this study, deep sequencing, genetic linkage analysis, and transcriptome data were used to produce and annotate a high-quality reference genome sequence. Reference genome sequence order was improved, 29.6 Mbp of additional sequence was incorporated, the number of genes annotated increased 24% to 34 211, average gene length and N50 increased, and error frequency was reduced 10-fold to 1 per 100 kbp. Subtelomeric repeats with characteristics of Tandem Repeats in Miniature (TRIM) elements were identified at the termini of most chromosomes. Nucleosome occupancy predictions identified nucleosomes positioned immediately downstream of transcription start sites and at different densities across chromosomes. Alignment of more than 50 resequenced genomes from diverse sorghum genotypes to the reference genome identified approximately 7.4 M single nucleotide polymorphisms (SNPs) and 1.9 M indels. Large-scale variant features in euchromatin were identified with periodicities of approximately 25 kbp. A transcriptome atlas of gene expression was constructed from 47 RNA-seq profiles of growing and developed tissues of the major plant organs (roots, leaves, stems, panicles, and seed) collected during the juvenile, vegetative and reproductive phases. Analysis of the transcriptome data indicated that tissue type and protein kinase expression had large influences on transcriptional profile clustering. The updated assembly, annotation, and transcriptome data represent a resource for C4 grass research and crop improvement

Preliminary evidence for human globus pallidus pars interna neurons signaling reward and sensory stimuli.

The globus pallidus pars interna (GPi) is a component of the basal ganglia, a network of subcortical nuclei that process motor, associative, and limbic information. While non-human primate studies have suggested a role for the GPi in non-motor functions, there have been no single-unit studies of non-motor electrophysiological behavior of human GPi neurons. We therefore sought to extend these findings by collecting single-unit recordings from awake patients during functional stereotactic neurosurgery targeting the GPi for deep brain stimulation. To assess cellular responses to non-motor information, patients performed a reward task where virtual money could be won, lost, or neither, depending on their performance while cellular activity was monitored. Changes in the firing rates of isolated GPi neurons after the presentation of reward-related stimuli were compared between different reward contingencies (win, loss, null). We observed neurons that modulated their firing rate significantly to the presentation of reward-related stimuli. We furthermore found neurons that responded to visual-stimuli more broadly. This is the first single-unit evidence of human GPi neurons carrying non-motor information. These results are broadly consistent with previous findings in the animal literature and suggest non-motor information may be represented in the single-unit activity of human GPi neurons.NAH is supported by a Unilever/Lipton Graduate Fellowship in Neuroscience and a University of Toronto Fellowship. WDH is supported by a CIHR operating grant (98006). VV is a Wellcome Trust (WT) intermediate Clinical Fellow (WT093705MA).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroscience.2016.04.02

A Parameterised Complexity Analysis of Bi-level Optimisation with Evolutionary Algorithms

Bi-level optimisation problems have gained increasing interest in the field of combinatorial optimisation in recent years. In this paper, we analyse the runtime of some evolutionary algorithms for bi-level optimisation problems. We examine two NP-hard problems, the generalised minimum spanning tree problem and the generalised travelling salesperson problem in the context of parameterised complexity. For the generalised minimum spanning tree problem, we analyse the two approaches presented by Hu and Raidl (2012) with respect to the number of clusters that distinguish each other by the chosen representation of possible solutions. Our results show that a (1+1) evolutionary algorithm working with the spanning nodes representation is not a fixed-parameter evolutionary algorithm for the problem, whereas the problem can be solved in fixed-parameter time with the global structure representation. We present hard instances for each approach and show that the two approaches are highly complementary by proving that they solve each other’s hard instances very efficiently. For the generalised travelling salesperson problem, we analyse the problem with respect to the number of clusters in the problem instance. Our results show that a (1+1) evolutionary algorithm working with the global structure representation is a fixed-parameter evolutionary algorithm for the problem

Skin regeneration-related mechanisms of Calcium Hydroxylapatite (CaHA): a systematic review

IntroductionCalcium Hydroxylapatite (CaHA) is a common dermal filler used in aesthetic medicine for volumizing and contouring. Understanding mechanisms of actions of CaHA can help improve our understanding of its clinical applications.MethodsWe performed a systematic review to summarize the skin-regeneration related mechanisms of CaHA. Five bibliographic databases were searched for English-language publications that evaluated CaHA in skin regeneration outcomes including neocollagenesis, cell proliferation and growth factors, angiogenesis, vascular dynamic and inflammatory markers, among others. Methodological rigor of included studies was assessed.ResultsOf 2,935 identified citations, 12 studies were included for final analysis. Collagen production was reported by nine studies, cell proliferation by four, elastic fibers and/or elastin by four, and three studies on angiogenesis, while limited studies were available on the other outcomes. Six were clinical/observational studies. Only seven studies had a control group. Overall, studies showed CaHA resulted in increased cell proliferation, increased collagen production and angiogenesis, as well as in higher elastic fiber and elastin formation. Limited and inconclusive evidence was available on the other mechanisms. The majority of the studies had methodological limitations.DiscussionCurrent evidence is limited but indicates several mechanisms through which CaHA could lead to skin regeneration, volume enhancement, and contouring.Systematic review registrationhttps://doi.org/10.17605/OSF.IO/WY49V

Recurring outbursts of the supernova impostor AT 2016blu in NGC 4559

We present the first photometric analysis of the supernova (SN) impostor AT 2016blu in NGC 4559. This transient was discovered by the Lick Observatory Supernova Search in 2012 and has continued its outbursts since then. Optical and infrared photometry of AT 2016blu reveals at least 19 outbursts in 2012-2022. Similar photometry from 1999-2009 shows no outbursts, indicating that the star was relatively stable in the decade before discovery. Archival {\it Hubble Space Telescope} observations suggest that the progenitor had a minimum initial mass of $M >= 33$ M$_{\odot}$ and a luminosity of $L >= 10^{5.7}$ L$_{\odot}$. AT 2016blu's outbursts show irregular variability with multiple closely spaced peaks having typical amplitudes of 1-2 mag and durations of 1-4 weeks. While individual outbursts have irregular light curves, concentrations of these peaks recur with a period of $\sim 113 \pm 2$ d. Based on this period, we predict times for upcoming outbursts in 2023 and 2024. AT 2016blu shares similarities with SN 2000ch in NGC 3432, where outbursts may arise from periastron encounters in an eccentric binary containing a luminous blue variable (LBV). We propose that AT 2016blu's outbursts are also driven by interactions that intensify around periastron in an eccentric system. Intrinsic variability of the LBV-like primary star may cause different intensity and duration of binary interaction at each periastron passage. AT 2016blu also resembles the periastron encounters of $\eta$ Carinae prior to its Great Eruption and the erratic pre-SN eruptions of SN 2009ip. This similarity and the onset of eruptions in the past decade hint that AT 2016blu may also be headed for a catastrophe, making it a target of great interest.Comment: 18 pages, 14 figures, 6 tables, MNRAS Accepte

Spring cleaning as a safety risk: results of a population-based study in two consecutive years

<p>Abstract</p> <p>Background</p> <p>Spring cleaning is a popular tradition in Iran as well as in many other countries. The purpose of our study was to determine the pattern and compare the incidence of spring cleaning related injuries in Tehran, in the years 2007 and 2008.</p> <p>Methods</p> <p>In the year 2007, a household survey was performed in Tehran by random cluster sampling. The survey was repeated in May 2008 with the same clusters and starting points, but different households. The incidence of spring cleaning related injuries, the age and sex of injured person(s), the mechanism, type and cost of injuries were recorded through semi-structured interviews. The incidence rates of injuries and injuries leading to health visits (severe) according to sex and age groups were calculated. Data were analyzed using SPSS and STATA statistical softwares.</p> <p>Results</p> <p>The incidence of all and severe spring cleaning related injuries were 3.8 (3.0 - 4.8) and 1.6 (1.1-2.3) per 1000, respectively. The most common mechanisms of injuries were falls, followed by cutting and lifting heavy objects or overexertion. Falls were also the main mechanism of severe injuries. The most common injuries were open wounds, followed by superficial injuries (including contusions) and sprain and strain. Among severe injuries, the most frequent injuries were open wounds and contusions, followed by dislocations. The injuries were most common among women with an incidence of about 8.4 per 1000 in women older than 18 years of age (severe injuries: 3.4 per 1000 (2.2-5.1)).</p> <p>Conclusion</p> <p>The incidence of spring cleaning related injuries is high enough to raise concern in health system authorities. It could be estimated that about 23,927 to 38,283 persons get injured during the spring cleaning in Tehran at the beginning of every Persian new year. In addition, about 8,773-18,344 of these cases are expected to be severe enough to lead to medical attention (considering 7,975,679 as the population of Tehran at the time of study). Improving awareness of families, especially young women, regarding the scope and importance of spring cleaning safety can be suggested as the first population-based strategy to decrease the incidence of these injuries.</p