4,905 research outputs found
Player agency in interactive narrative: audience, actor & author
The question motivating this review paper is, how can
computer-based interactive narrative be used as a constructivist learn-
ing activity? The paper proposes that player agency can be used to
link interactive narrative to learner agency in constructivist theory,
and to classify approaches to interactive narrative. The traditional
question driving research in interactive narrative is, āhow can an in-
teractive narrative deal with a high degree of player agency, while
maintaining a coherent and well-formed narrative?ā This question
derives from an Aristotelian approach to interactive narrative that,
as the question shows, is inherently antagonistic to player agency.
Within this approach, player agency must be restricted and manip-
ulated to maintain the narrative. Two alternative approaches based
on Brechtās Epic Theatre and Boalās Theatre of the Oppressed are
reviewed. If a Boalian approach to interactive narrative is taken the
conflict between narrative and player agency dissolves. The question
that emerges from this approach is quite different from the traditional
question above, and presents a more useful approach to applying in-
teractive narrative as a constructivist learning activity
A Comparison of Grassland Management Systems for Beef Cattle Using Self-Contained Farmlets: Effects of Contrasting Nitrogen Inputs and Management Strategies on the Farm Economy
The financial implications of manipulating nitrogen (N) inputs and management strategies for beef production systems were assessed. One-hectare grassland farmlets were grazed to a target sward height by beef steers; herbage surplus to grazing requirements was cut for silage. Three systems were compared: āCNā, conventional mineral N application to a grass monoculture and broadcast slurry; āTNā, tactical mineral N application at fortnightly intervals to a grass monoculture with slurry injection and the early housing of cattle; āGCā, a mixed grass/white clover sward with no mineral N addition and slurry injection. Comparisons were made on two contrasting soil types: a freely-draining sandy loam (site 1) and a poorly drained clay (site 2). Financial budgets for 1999-2000 show that estimated gross profit margins (gross outputs minus variable costs), after deducting contractorās charges for sward preparation and fertiliser spreading, were highest for treatment CN at both sites Ć(ā¬1552, ā¬1356 and ā¬1461 ha-1 for site 1 and ā¬1562, ā¬1281 and ā¬1287 ha-1 for site 2, for treatments CN, TN and GC, respectively). Treatment TN was penalised by increased costs associated with an extended housed period and the need to purchase additional silage for winter feeding which cost ā¬242 ha-1 at site 1 and ā¬250 ha-1 at site 2. Savings in N fertiliser for TN in comparison with CN (ā¬44 ha-1 at site 1 and ā¬39 ha-1 at site 2) were more than offset by the increased costs of fortnightly fertiliser applications (ā¬54 ha-1 at site 1 and ā¬46 ha-1 at site 2). Treatment GC benefited from zero costs for the purchase and spreading of mineral N fertiliser but was penalised by increased variation in forage DM production which resulted in a shortfall in winter fodder requirements with a replacement cost of ā¬250 at site 1 and ā¬435 at site 2. The best overall economic performance after the allocation of all possible relevant costs (variable, fixed and capital) in terms of the relative net profit margin, was for GC at site 1 and for CN at site 2 (-ā¬1358, -ā¬2399 and -ā¬1304 ha-1 at site 1 and -ā¬1122, -ā¬2810 and - ā¬1380 ha-1 at site 2, for CN, TN and GC, respectively). The opportunity costs of reducing N surpluses at the gross profit margin level (after contractorās charges) for treatments TN and GC over treatment CN were calculated at ā¬2.29 kg-1 N surplus for TN and ā¬0.67 kg-1 N surplus for GC at site 1, with corresponding values of ā¬4.91 and ā¬1.57 at site 2.Farmlets, Systems, Beef cattle, Nitrogen, Slurry, Animal production, Economics, UK, Farm Management,
Solving the Poisson equation on small aspect ratio domains using unstructured meshes
We discuss the ill conditioning of the matrix for the discretised Poisson
equation in the small aspect ratio limit, and motivate this problem in the
context of nonhydrostatic ocean modelling. Efficient iterative solvers for the
Poisson equation in small aspect ratio domains are crucial for the successful
development of nonhydrostatic ocean models on unstructured meshes. We introduce
a new multigrid preconditioner for the Poisson problem which can be used with
finite element discretisations on general unstructured meshes; this
preconditioner is motivated by the fact that the Poisson problem has a
condition number which is independent of aspect ratio when Dirichlet boundary
conditions are imposed on the top surface of the domain. This leads to the
first level in an algebraic multigrid solver (which can be extended by further
conventional algebraic multigrid stages), and an additive smoother. We
illustrate the method with numerical tests on unstructured meshes, which show
that the preconditioner makes a dramatic improvement on a more standard
multigrid preconditioner approach, and also show that the additive smoother
produces better results than standard SOR smoothing. This new solver method
makes it feasible to run nonhydrostatic unstructured mesh ocean models in small
aspect ratio domains.Comment: submitted to Ocean Modellin
An evaluation of the ATM man/machine interface. Phase 3: Analysis of SL-3 and SL-4 data
The functional adequacy of human factored crew operated systems under operational zero-gravity conditions is considered. Skylab ATM experiment operations generated sufficient telemetry and voice transcript data to support such an assessment effort. Discussions are presented pertaining to the methodology and procedures used to evaluate the hardware, training and directive aspects of Skylab 3 and Skylab 4 manned ATM experiment operations
Comment on "A note on generalized radial mesh generation for plasma electronic structure"
In a recent note [High Energy Density Phys. 7, 161 (2011)], B.G. Wilson and
V. Sonnad proposed a very useful closed form expression for the efficient
generation of analytic log-linear radial meshes. The central point of the note
is an implicit equation for the parameter h, involving Lambert's function W[x].
The authors mention that they are unaware of any direct proof of this equation
(they obtained it by re-summing the Taylor expansion of h using high-order
coefficients obtained by analytic differentiation of the implicit definition
using symbolic manipulation). In the present comment, we present a direct proof
of that equation.Comment: submitted to "High Energy Density Physics
Lead in Birds
Lead is a highly toxic heavy metal that acts as a nonspecific poison affecting all body systems and has no known biological requirement. Absorption of low concentrations may result in a wide range of sublethal effects in animals, and higher concentrations may result in mortality (Demayo et al. 1982).
Lead has been mined and smelted by humans for centuries, but the use of lead-based products increased greatly following the Industrial Revolution. Consequently, lead today is ubiquitous in air, water, and soil, in both urban and rural environments (Eisler 2000). Vertebrates are exposed to lead mainly via inhalation and ingestion. A proportion of lead entering the body is absorbed into the bloodstream and subsequently becomes distributed among body tissues, primarily the blood, liver, kidney, and bone. As a result of anthropogenic activities, most animals have higher tissue lead concentrations than in preindustrialized times. Although even very low tissue lead concentrations have some measurable physiological effects, the concentrations usually encountered in the wider environment (i.e., distant from lead emission sources) have not generally been considered to directly affect survival of most wildlife
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