Conditional fiducial models

The fiducial is not unique in general, but we prove that in a restricted class of models it is uniquely determined by the sampling distribution of the data. It depends in particular not on the choice of a data generating model. The arguments lead to a generalization of the classical formula found by Fisher (1930). The restricted class includes cases with discrete distributions, the case of the shape parameter in the Gamma distribution, and also the case of the correlation coefficient in a bivariate Gaussian model. One of the examples can also be used in a pedagogical context to demonstrate possible difficulties with likelihood-, Bayesian-, and bootstrap-inference. Examples that demonstrate non-uniqueness are also presented. It is explained that they can be seen as cases with restrictions on the parameter space. Motivated by this the concept of a conditional fiducial model is introduced. This class of models includes the common case of iid samples from a one-parameter model investigated by Hannig (2013), the structural group models investigated by Fraser (1968), and also certain models discussed by Fisher (1973) in his final writing on the subject

On the proper treatment of improper distributions

The axiomatic foundation of probability theory presented by Kolmogorov has been the basis of modern theory for probability and statistics. In certain applications it is, however, necessary or convenient to allow improper (unbounded) distributions, which is often done without a theoretical foundation. The paper reviews a recent theory which includes improper distributions, and which is related to Renyi's theory of conditional probability spaces. It is in particular demonstrated how the theory leads to simple explanations of apparent paradoxes known from the Bayesian literature. Several examples from statistical practice with improper distributions are discussed in light of the given theoretical results, which also include a recent theory of convergence of proper distributions to improper ones.Comment: Journal of Statistical Planning and Inference, 201

Cardiovascular Adjustments to Gravitational Stress

The effects of gravity on the cardiovascular system must be taken into account whenever a hemodynamic assessment is made. All intravascular pressure have a gravity-dependent hydrostatic component. The interaction between the gravitational field, the position of the body, and the functional characteristics of the blood vessels determines the distribution of intravascular volume. In turn this distribution largely determines cardiac pump function. Multiple control mechanisms are activated to preserve optimal tissue perfusion when the magnitude of the gravitational field or its direction relative to the body changes. Humans are particularly sensitive to such changes because of the combination of their normally erect posture and the large body mass and blood volume below the level of the heart. Current aerospace technology also exposes human subjects to extreme variations in the gravitational forces that range from zero during space travel to as much an nine-times normal during operation of high-performance military aircraft. This chapter therefore emphasizes human physiology

Paired composite fermion phase of quantum Hall bilayers at \nu = 1/2 + 1/2

We provide numerical evidence for composite fermion pairing in quantum Hall bilayer systems at filling $\nu=1/2 + 1/2$ for intermediate spacing between the layers. We identify the phase as $p_x + i p_y$ pairing, and construct high accuracy trial wavefunctions to describe the groundstate on the sphere. For large distances between the layers, and for finite systems, a competing "Hund's rule" state, or composite fermion liquid, prevails for certain system sizes. We argue that for larger systems, the pairing phase will persist to larger layer spacing.Comment: 4 pages, 2 figures; v2: final version, as published in journa

Skyrmions in the Moore-Read state at nu=5/2

We study charged excitations of the non-abelian Moore-Read liquid at filling factor nu=5/2, allowing for spin depolarization. Using a combination of numerical studies, and taking account of non-zero well widths, we find that at sufficiently low Zeeman energy it is energetically favourable for charge e/4 quasiholes to bind into "skyrmions" of charge e/2. We show that skyrmion formation is further promoted by disorder, and argue that this can lead to a depolarized nu=5/2 ground state in realistic experimental situations. We comment on the consequences for the activated transport.Comment: 4 pages, 3 figure

Exploring the Evolution of the Mousetrap

This paper contributes to a pedagogical approach to teaching design related to social development by presenting and discussing the technical-solution and design evolution of a simple, everyday product. There is a need to explore the influence of social developments on approaches to product development and design solutions. It is important that students experience and observe how social conventions influence design. This paper investigates whether the evolution of the mousetrap has been driven by highly pragmatic and ergonomic influences or by certain social developments influencing how the (Western) world behaves towards fundamental questions, such as the issue of death. A case study of mousetraps focuses on what has been a principal solution of mousetrap construction from the first patented trap in the early 1900s to the latest models: a stroke against the neck of mice. How has the evolution of this solution been expressed in the objects? Immaterial values are reflected in the traps, and this case study shows how social norms can outweigh technical and ergonomic considerations in product development. Describing and analysing the history of the trap and considering relevant theory can have an impact on design students to reflect more on the market and social awareness. Using specific and typical examples from the history of the mousetrap and visually showing how the development of the trap over more than 100 years will contribute to understanding the complex issues involved in simple, everyday objects

Exploring the design of mousetraps

Based on a case study of a collection of a couple of hundred mousetraps this paper presents a systematic categorisation of their principles of technical construction, material consistence and principles of function. This study of mousetraps introduces decision making involving ethical dilemmas, the discussion of intrinsic value of animals of this kind, and finally the user’s need to be comfortable with the process of use. The principle of its technical construction among a large diversity of possible solutions must be chosen on the basis of a set of criteria. Equal for all traps is the demand for inclusive usability and low cost results. This criterion promotes low-tech constructions with high visual transparency. The presentation of the mousetrap study introduces in a way the general connections between material and technical constructions and moral consequences of ethical perspectives. Ethical values are guidelines in the decision making. Together with a categorisation and presentation of technical principles of mousetraps, the graphical design illustrations and text information on the belonging packaging shows in a pedagogical way how it is possible to contribute to complex issues with simple everyday object