The attraction of contributors in free and open source software projects

As firms increasingly sanction an open sourcing strategy, the question of which open source project to undertake remains tentative. The lack of established metrics makes it difficult to formulate such strategy. While many projects have been formed and created, only a few managed to remain active. With the majority of these projects failing, firms need a reliable set of criteria to assess what makes a project appealing not only to developers but also to visitors, users and commercial sponsors. In this paper, we develop a theoretical model to explore the contextual and causal factors of project attractiveness in inducing activities such as source code contribution, software maintenance, and usage. We test our model with data derived from more than 4000 projects spanning 4 years. Our main findings include that projects’ set of conditions such as license restrictiveness and their available resources provide the context that directly influence the amount of work activities observed in the projects. It was also found that indirect and unintended contributions such as recommending software, despite of being non-technical, cannot be ignored for project activeness, diffusion and sustainability. Finally, our analysis provide evidence that higher attractiveness leads to more code-related activities with the downside of slowing down responsiveness to address projects’ tasks, such as the implementation of new features and bug fixes. Our model underscores the significance of the reinforcing effects of attractiveness and work activities in open source projects, giving us the opportunity to discuss strategies to manage common traps such as the liability of newness. We conclude by discussing the applicability of the research model to other user-led initiatives.     

Effect of salt on oxidative changes in pre- and post-rigor ground beef

Pre- and post-rigor beef was ground and salt was added to give 0·0, 0·5, 2·0 and 4·0% NaCl (w/w). Samples were removed after 0, 24, 48, 72 and 96 h at 4°C and analyzed for pH, TBA numbers and percentages of reduced myoglobin (Mb), metmyoglobin (MMb) and oxymyoglobin (MbO(2)). After holding for 96 h the samples were cooked in a boiling water bath to an internal temperature of 80°C and held at 4°C for 48 h before TBA analysis. Pre-rigor grinding and salting reduced the post-mortem pH decline and the extent of meat discoloration as shown by the differences in the amount of MMb. The extent of lipid oxidation as measured by TBA numbers was not significantly different for the pre- and post-rigor ground salted meat samples, although salt accelerated oxidation during storage. Results demonstrated that pre-rigor grinding and salting of beef produces a more stable bright red color, which appears to be associated with a lower percentage of MMb and a higher ultimate pH in the pre-rigor salted meat.     

Structural elucidation of direct analysis in real time ionized nerve agent simulants with infrared multiple photon dissociation spectroscopy

Infrared multiple photon dissociation (IRMPD) was used to generate vibrational spectra of ions produced with a direct analysis in real time (DART) ionization source coupled to a 4.7 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The location of protonation on the nerve agent simulants diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP) was studied while solutions of the compounds were introduced for extended periods of time with a syringe pump. Theoretical vibrational spectra were generated with density functional theory calculations. Visual comparison of experimental mid-IR IRMPD spectra and theoretical spectra could not establish definitively if a single structure or a mixture of conformations was present for the protonated parent of each compound. However, theoretical calculations, near-ir IRMPD spectra, and frequency-to-frequency and statistical comparisons indicated that the protonation site for both DIMP and DMMP was predominantly, if not exclusively, the phosphonyl oxygen instead of one of the oxygen atoms with only single bonds.     

Characterization of a baculovirus-encoded ATP-dependent DNA ligase

Sequence analysis of the Lymantria dispar multicapsid nucleopolyhedrovirus (LdMNPV) genome identified an open reading frame (ORF) encoding a 548-amino-acid (62-kDa) protein that showed 35% amino acid sequence identity with vaccinia virus ATP-dependent DNA ligase. Ligase homologs have not been reported from other baculoviruses. The ligase ORF was cloned and expressed as an N-terminal histidine-tagged fusion protein. Incubation of the purified protein with [alpha-32P]ATP resulted in formation of a covalent enzyme-adenylate intermediate which ran as a 62-kDa labeled band on a sodium dodecyl sulfate-polyacrylamide gel. Loss of the radiolabeled band occurred upon incubation of the intermediate with pyrophosphate, poly(dA) . poly(dT)12-18, or poly(rA) . poly(dT)12-18, characteristics of a DNA ligase II or III. The protein was able to ligate a double-stranded synthetic DNA substrate containing a single nick and inefficiently ligated a 1-nucleotide (nt) gap but did not ligate a 2-nt gap. It was able to ligate short, complementary overhangs but not blunt-ended double-stranded DNA. In a transient DNA replication assay employing six plasmids containing the LdMNPV homologs of the essential baculovirus replication genes, a plasmid containing the DNA ligase gene was neither essential nor stimulatory. All of these results are consistent with the activity of type III DNA ligases, which have been implicated in DNA repair and recombination.     

A developmental perspective on the study of depression: Children's evaluative reactions to sadness.

Examined developmental differences in emotional expression. It is suggested that there are cognitive and character structures that may be prerequisites for certain adult reactions to painful life events. The self-denigrating adult may be a discrepancy between self-representation and ideal self. In a child, these structures may not yet be stable enough to withstand such critical self-appraisal. 35 5- and 7-yr-olds were asked to give liking ratings to hypothetical children who had undergone a painful life event and to give evaluative ratings of themselves in the same situations. Older Ss evaluated a hypothetical other and themselves negatively, whereas the 5-yr-olds could not extend their negative evaluation of a sad other to themselves. Results are discussed in terms of developmental changes in the depressive reaction. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An algorithm for near-optimal placement of sensor elements

An important question in array design is that of where to place the elements of a sparse array for optimal performance in terms of its ability to detect and resolve a greater number of sources than conventionally possible. In particular, it has been shown that when sensor elements are arranged in the minimum redundancy fashion, by performing an augmentation technique on the covariances obtained from the array outputs, an M element array can be made to estimate the directions of arrival of as many as M(M-1)/2 uncorrelated sources unambiguously. Constructive procedures are developed to evaluate integer locations for an array of given sensors that span a prescribed distance, such that any missing integer is expressible as the difference of two sensor locations. New upper bounds for the ratio of the square of the minimum number of elements to the spanning distance are also established     

The role of market and technical downsizing in reducing carbon emissions from the Swedish new car fleet

Doubts have been raised on whether the car industry will manage to reach the goal set by the Voluntary Agreement with the European Commission, unless tougher measures are taken to reduce CO₂ emissions. Taking a stance from the concept of downsizing, we study the historical development of two strategies: first, shifting the market toward smaller cars, market downsizing; second, a technical downsizing, i.e., technical improvements that have enabled a reduction of engine size. We focus on the Swedish new car market from 1975 to 2002. Analysis is done by combining sales statistics with databases over car model parameters. The development of the top and bottom 10% and 20% of the car market of various parameters points to an increased differentiation of the market; still, the market share of small models remains low. We identify the potential for downsizing created by increase of maximum specific torque and power and conclude that these have enabled the cylinder volume to stabilize around 2 l. Increase in engine size has also partly been dampened by the utilization of supercharging. The potential savings of fuel use presented by the introduction of a sixth gear in manual gearboxes have not materialized since gearshifts have not systematically been used to lower engine speed. We conclude that there are few signs of a downsizing in the Swedish new car fleet. From a market perspective, larger cars are still dominant and the technical potentials to reduce engine size have not been harnessed.

A peculiar form of amicrobial pustulosis of the folds associated with systemic lupus erythematosus and other auto-immune diseases

This article continues the series of electronic microscopical investigations of tick attachment and host's inflammatory reaction in the attachment site. In all this works we used larvae of different Ixodid ticks but the same species of the host (white mouse), Ixodid species having different type of attachment. Dermacentor marginatus (Amosova, 1989a) is characterized by the superficial penetration of mouth parts, the abundance of cement around them and on the surface of the host's skin, the mouth parts of Hyalomma asiaticum are fully inserted and the superficial cement is minimal (Amosova, 1989b) and Ixodes ricinus has mouth parts inserted more deeply in the skin tissue of the host and the cement substance localised only on the surface of the skin at the 1st and 2nd days of feeding period. For this investigation we choose Haemaphysalis longicornis because it is known (see Kemp et al., 1982) that genus Haemaphysalis has the most superficial localisation of the mouth parts in the attachment site. We have studied a fine structure of cement cone and the cement substance surrounding the mouth parts in the skin and have demonstrated that it is very similar to the Dermacentor marginatus cement structure. The pattern of cellular response is similar to D. marginatus lesion too.     

Trauma, dissociation, and conflict: The space where neuroscience, cognitive science, and psychoanalysis overlap.

The authors describe their scientific and clinical interests in developing the panel Trauma, Dissociation, and Conflict: The Space Where Neuroscience, Cognitive Science, and Psychoanalysis Overlap, given at the 22nd Annual Spring Meeting of the Division of Psychoanalysis of the American Psychological Association. They cite the influence of the panelists, Philip M. Bromberg, Wilma Bucci, and Joseph LeDoux, on their own work. Specializing in the treatment of chronic pain, Anderson has developed a relational intersubjective technique informed by this interdisciplinary approach. Gold's work has focused on the distinction between dissociative processes and repression in traumatic memory. The relevance of trauma, dissociation, and conflict, heightened since September 11, 2001, could not have been anticipated in the planning of the panel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)