Multiplayer Cost Games with Simple Nash Equilibria

Multiplayer games with selfish agents naturally occur in the design of distributed and embedded systems. As the goals of selfish agents are usually neither equivalent nor antagonistic to each other, such games are non zero-sum games. We study such games and show that a large class of these games, including games where the individual objectives are mean- or discounted-payoff, or quantitative reachability, and show that they do not only have a solution, but a simple solution. We establish the existence of Nash equilibria that are composed of k memoryless strategies for each agent in a setting with k agents, one main and k-1 minor strategies. The main strategy describes what happens when all agents comply, whereas the minor strategies ensure that all other agents immediately start to co-operate against the agent who first deviates from the plan. This simplicity is important, as rational agents are an idealisation. Realistically, agents have to decide on their moves with very limited resources, and complicated strategies that require exponential--or even non-elementary--implementations cannot realistically be implemented. The existence of simple strategies that we prove in this paper therefore holds a promise of implementability.Comment: 23 page

Bostonia. Volume 12

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Towards an understanding of game software development processes: a case study

This paper aims to fill the gap that exists about software development processes in game development in the research literature, and address the gap in the research literature by investigating and reporting information about the software development processes used in game development. To investigate the role of the software development process in relation to the game development process, and to better understand the processes and practices used in game software development, a single industrial based case study was undertaken and reported to investigate in a real world context the software development processes and practices used in game development. This research contributes to our knowledge of the field of game development and potentially forms the foundation for further research in the area

Frontal sinus mucocele with orbital extension drained via a combined upper lid skin crease and endoscopic approach.

This case report discusses the ophthalmic complications of frontal sinus mucoceles and describes the favorable long-term surgical outcomes of a combined endoscopic and upper-lid skin crease drainage approach carried out jointly with otorhinolaryngology. A 47-year-old single mother presented to eye casualty with markedly swollen eyelids and visual acuity of 6/6 in the left eye, no perception of light in the right. Ophthalmic examination revealed right-sided hypoglobus and proptosis with exposure keratopathy inferiorly. There was complete ophthalmoplegia in the right eye and a hemorrhagic optic disc visible on fundoscopy. CT orbit with contrast confirmed a diagnosis of giant frontal mucocele with orbital extension. The patient underwent mucocele drainage via a modified anterior orbitotomy approach and FESS (Functional Endoscopic Sinus Surgery) drainage performed jointly with otorhinolaryngology. Two weeks post-operatively her proptosis was resolving and by three months she had regained full extraocular motility. As expected, vision was not restored in the right eye. At one year, the patient's upper lid skin crease scar was completely buried in the eyelid's natural contour, and repeat CT scanning confirmed no re-stenosis or mucocele recurrence. This case demonstrates, that a multidisciplinary approach to far-lateral frontal sinus mucoceles with orbital extension and ophthalmic complications which combines an upper lid skin crease incision with FESS drainage, allows adequate access to the frontal sinus while preserving cosmesis

Propagation of ultrahigh energy nuclei in clusters of galaxies: resulting composition and secondary emissions

We study the survival of ultrahigh energy nuclei injected in clusters of galaxies, as well as their secondary neutrino and photon emissions, using a complete numerical propagation method and a realistic modeling of the magnetic, baryonic and photonic backgrounds. It is found that the survival of heavy nuclei highly depends on the injection position and on the profile of the magnetic field. Taking into account the limited lifetime of the central source could also lead in some cases to the detection of a cosmic ray afterglow, temporally decorrelated from neutrino and gamma ray emissions. We calculate that the diffusive neutrino flux around 1 PeV coming from clusters of galaxies may have a chance to be detected by current instruments. The observation of single sources in neutrinos and in gamma rays produced by ultrahigh energy cosmic rays will be more difficult. Signals coming from lower energy cosmic rays (E < 1 PeV), if they exist, might however be detected by Fermi, for reasonable sets of parameters.Comment: 19 pages, 15 figures, version to appear in ApJ (minor changes

Diluting education? An ethnographic study of change in an Australian Ministry of Education

This ethnographic study captures the processes that led to change in an Australian public education system. The changes were driven by strong neo-liberal discourses which resulted in a shift from a shared understanding about leading educational change in schools by knowledge transfer to managing educational change as a process, in other words, allowing the schools to decide how to change. Inside an Australian state education bureaucracy at a time when the organisation was restructured and services decentralised, this study helps show some of the disturbing trends resulting from the further entrenchment of neo-liberal strategies. Although control was re-centralised by legitimising performance mechanisms, in the form of national testing, there are indications that the focus on national tests may have alarming consequences for the content and context of education. I argue that the complexities of learning and fundamental pedagogies are being lost in preference for an over reliance on data systems that are based on a shallow and narrow set of standardised measures

Disruption of estrogen receptor DNA-binding domain and related intramolecular communication restores tamoxifen sensitivity in resistant breast cancer

SummaryA serious obstacle to successful treatment of estrogen receptor (ER)-positive human breast cancer is cell resistance to tamoxifen (TAM) therapy. Here we show that the electrophile disulfide benzamide (DIBA), an ER zinc finger inhibitor, blocks ligand-dependent and -independent cell growth of TAM-resistant breast cancer in vitro and in vivo. Such inhibition depends on targeting disruption of the ER DNA-binding domain and its communication with neighboring functional domains, facilitating ERα dissociation from its coactivator AIB1 and concomitant association with its corepressor NCoR bound to chromatin. DIBA does not affect phosphorylation of HER2, MAPK, AKT, and AIB1, suggesting that DIBA-modified ERα may induce a switch from agonistic to antagonistic effects of TAM on resistant breast cancer cells

An individual based computational model of intestinal crypt fission and its application to predicting unrestrictive growth of the intestinal epithelium.

Intestinal crypt fission is a homeostatic phenomenon, observable in healthy adult mucosa, but which also plays a pathological role as the main mode of growth of some intestinal polyps. Building on our previous individual based model for the small intestinal crypt and on in vitro cultured intestinal organoids, we here model crypt fission as a budding process based on fluid mechanics at the individual cell level and extrapolated predictions for growth of the intestinal epithelium. Budding was always observed in regions of organoids with abundant Paneth cells. Our data support a model in which buds are biomechanically initiated by single stem cells surrounded by Paneth cells which exhibit greater resistance to viscoelastic deformation, a hypothesis supported by atomic force measurements of single cells. Time intervals between consecutive budding events, as simulated by the model and observed in vitro, were 2.84 and 2.62 days, respectively. Predicted cell dynamics was unaffected within the original crypt which retained its full capability of providing cells to the epithelium throughout fission. Mitotic pressure in simulated primary crypts forced upward migration of buds, which simultaneously grew into new protruding crypts at a rate equal to 1.03 days-1 in simulations and 0.99 days-1 in cultured organoids. Simulated crypts reached their final size in 4.6 days, and required 40 6.2 days to migrate to the top of the primary crypt. The growth of the secondary crypt is independent of its migration along the original crypt. Assuming unrestricted crypt fission and multiple budding events, a maximal growth rate of the intestinal epithelium of 0.10 days-1 43 is predicted and thus approximately 22 days are required for a 10-fold increase of polyp size. These predictions are in agreement with the time reported to develop macroscopic adenomas in mice after loss of Apc in intestinal stem cells