Simulating realistic disk galaxies with a novel sub-resolution ISM model

We present results of cosmological simulations of disk galaxies carried out with the GADGET-3 TreePM+SPH code, where star formation and stellar feedback are described using our MUlti Phase Particle Integrator (MUPPI) model. This description is based on simple multi-phase model of the interstellar medium at unresolved scales, where mass and energy flows among the components are explicitly followed by solving a system of ordinary differential equations. Thermal energy from SNe is injected into the local hot phase, so as to avoid that it is promptly radiated away. A kinetic feedback prescription generates the massive outflows needed to avoid the over-production of stars. We use two sets of zoomed-in initial conditions of isolated cosmological halos with masses (2-3) * 10^{12} Msun, both available at several resolution levels. In all cases we obtain spiral galaxies with small bulge-over-total stellar mass ratios (B/T \approx 0.2), extended stellar and gas disks, flat rotation curves and realistic values of stellar masses. Gas profiles are relatively flat, molecular gas is found to dominate at the centre of galaxies, with star formation rates following the observed Schmidt-Kennicutt relation. Stars kinematically belonging to the bulge form early, while disk stars show a clear inside-out formation pattern and mostly form after redshift z=2. However, the baryon conversion efficiencies in our simulations differ from the relation given by Moster et al. (2010) at a 3 sigma level, thus indicating that our stellar disks are still too massive for the Dark Matter halo in which they reside. Results are found to be remarkably stable against resolution. This further demonstrates the feasibility of carrying out simulations producing a realistic population of galaxies within representative cosmological volumes, at a relatively modest resolution.Comment: 19 pages, 21 figures, MNRAS accepte

Risk and Volatility: Econometric Models and Financial Practice

The advantage of knowing about risks is that we can change our behavior to avoid them. Of course, it is easily observed that to avoid all risks would be impossible; it might entail no flying, no driving, no walking, eating and drinking only healthy foods and never being touched by sunshine. Even a bath could be dangerous. I could not receive this prize if I sought to avoid all risks. There are some risks we choose to take because the benefits from taking them exceed the possible costs. Optimal behavior takes risks that are worthwhile. This is the central paradigm of finance; we must take risks to achieve rewards but not all risks are equally rewarded. Both the risks and the rewards are in the future, so it is the expectation of loss that is balanced against the expectation of reward. Thus we optimize our behavior, and in particular our portfolio, to maximize rewards and minimize risks.time series;

Notes from Break-out Sessions during IA’s Plenary on Assessment October 2, 2009

Imagining America\u27s recent national conference in New Orleans featured a plenary on Assessing the Practices of Public Scholarship (APPS). Panelists made “state of the field” remarks concerning engaged courses and projects in the arts, humanities, and design, as well as across these fields and as incorporated into social sciences and other disciplines. Facilitated break-out groups then discussed current methods of evaluating public scholarship for faculty, students, and community members, as well as metrics for tracking institutional change, and strategies for IA’s future research and delivery on this topic. The break-out group facilitators asked the following questions, which are followed by the most recurring responses and some miscellaneous remarks from participants

The use of modelling in purchasing/supply management research

The purpose of this research to explore the use of modelling in the field of Purchasing and Supply Management (P/SM). We are particularly interested in identifying the specific areas of P/SM where there are opportunities for the use of modelling based methods. The paper starts with an overview of main types of modelling and also provides a categorisation of the main P/SM research themes. Our research shows that there are many opportunities for using descriptive, predictive and prescriptive modelling approaches in all areas of P/SM research from the ones with a focus on the actual function from a purely operational and execution perspective (e.g. purchasing processes and behaviour) to the ones with a focus on the organisational level from a more strategic perspective (e.g. strategy and policy). We conclude that future P/SM research needs to explore the value of modelling not just at the functional or operational level, but also at the organisation and strategic level respectively. We also acknowledge that while using empirical results to inform and improve models has advantages, there are also drawbacks, which relate to the value, the practical relevance and the generalisability of the modelling based approaches

Research tools for design. Spatial layout and patterns of users' behaviour

The publication proposes a critical reading of the results emerging from the Seminar organised in January 2010 by the Department of Architectural and Design Technology on research tools for the architectural project. The spatial layout of buildings and urban spaces influences behaviour and the relations of the users, and in this displays the social nature of the architectural function in comparison to other spheres of design. Space Syntax (theory, methodology and techniques for the analysis of complex systems) takes this theory as the basis for its research. The seminar, attended by leading academic and professional figures, offered the opportunity for exchange between its own research and the experiences carried forward by the Space Syntax research and consultancy group

Great Expectations: Law, Employment Contracts, and Labor Market Performance

This chapter reviews the literature on employment and labor law. The goal of the review is to understand why every jurisdiction in the world has extensive employment law, particularly employment protection law, while most economic analysis of the law suggests that less employment protection would enhance welfare. The review has three parts. The first part discusses the structure of the common law and the evolution of employment protection law. The second part discusses the economic theory of contract. Finally, the empirical literature on employment and labor law is reviewed. I conclude that many aspects of employment law are consistent with the economic theory of contract – namely, that contracts are written and enforced to enhance ex ante match efficiency in the presence of asymmetric information and relationship specific investments. In contrast, empirical labor market research focuses upon ex post match efficiency in the face of an exogenous productivity shock. Hence, in order to understand the form and structure of existing employment law we need better empirical tools to assess the ex ante benefits of employment contracts.employment law, labor law, employment contract, employment contract, law and economics

Writer-researcher-facilitator:An integrative model for creative writers working in wellbeing contexts and beyond

In this paper we introduce an integrative model for working as a creative writer-researcher-facilitator (W-R-F). During the process of designing a new MA in Creative Writing and Wellbeing, we realized that we wanted to reexamine the complex interrelationships between the different strands of our work, in order to provide a framework within which our students could explore their own evolving practice. The model that we present here has emerged from this ongoing process of reflection and conversation in relation to our own practice, and was subsequently developed collaboratively with a group of practitioners working in the context of writing and wellbeing. We have found that creative exploration of these three interdependent aspects of our own lives—writing-researching-facilitating—can help us to recognize practical ways in which to integrate them into a more cohesive whole. We believe that this model also suggests ways for writer-researcher-facilitators to support one another in sharing best practice and in advancing developments in the field. We hope to begin a further conversation that will be immediately applicable to those working in the area of writing and wellbeing, but also to anyone negotiating the challenges, tensions and creative synergies inherent to living as a writer in the world

Forest biometrics and quantitative analysis of forested ecoystems in coastal Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2014.Growth and yield models are a mainstay of forestry research and a necessary tool in the forest management decision process. Growth and yield models predict forest population dynamics over time and are an invaluable resource to forest managers making harvest and utilization decisions. At present, there are only a few growth models available for Alaska's coastal forests, all of which are either calibrated with even-aged data or outdated. Yield tables and growth models developed with even-aged data can be useful in even-aged management applications such as clear-cuts; however, these models are not able to predict the outcomes of uneven-aged silvicutural systems. The objective of this thesis is the development of a growth and yield model for coastal Alaska and computer applications to facilitate its use. A density-dependent, distance-independent, size- and species-specific matrix forest growth and yield model is calibrated with data collected on permanent sample plots located throughout coastal Alaska. The resulting growth and yield model enables short- and long-term predictions of stand basal area, volume, and biomass. Model assessment, with a focus on plausibility and accuracy, is evaluated on an independent dataset. Two computer programs (AlaskaPro and fgmod) are developed in conjunction with the new model. These programs can be used by forest researchers and land managers to compare the outcomes of various silvicultural prescriptions