A Decade of Experimental Research on Spatial Models of Elections and Committees

The Euclidean representation of political issues and alternative outcomes, and the associated representation of preferences as quasi-concave utility functions is by now a staple of formal models of committees and elections. This theoretical development, moreover, is accompanied by a considerable body of experimental research. We can view that research in two ways: as a test of the basic propositions about equilibria in specific institutional settings, and as an attempt to gain insights into those aspects of political processes that are poorly understood or imperfectly modeled, such as the robustness of theoretical results with respect to procedural details and bargaining environments. This essay reviews that research so that we can gain some sense of its overall import

Performance of charge-injection-device infrared detector arrays at low and moderate backgrounds

Three 2 x 64 element charge injection device infrared detector arrays were tested at low and moderate background to evaluate their usefulness for space based astronomical observations. Testing was conducted both in the laboratory and in ground based telescope observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3x10 sq root of W/Hz. Array well capacity was measured to be significantly smaller than predicted. The measured sensitivity, which compares well with that of nonintegrating discrete extrinsic silicon photoconductors, shows these arrays to be useful for certain astronomical observations. However, the measured readout efficiency and frequency response represent serious limitations in low background applications

Elections with Limited Information: A Multidimensional Model

We develop a game theoretic model of 2 candidate competition over a multidimensional policy space, where the participants have incomplete information about the preferences and strategy choices of other participants. The players consist of the voters and the candidates. Voters are partitioned into two classes, depending on the information they observe. Informed voters observe candidate strategy choices while uninformed voters do not. All players (voters and candidates alike) observe contemporaneous poll data broken down by various subgroups of the population. The main results of the paper give conditions on the number and distribution of the informed and uninformed voters which are sufficient to guarantee that any equilibrium (or voter equilibrium) extracts all information

Experiments on the Core: Some Disconcerting Results for Majority Rule Voting Games

In the context of spatial majority voting games, considerable experimental support exists for the core as a solution hypothesis when it exists (c.f. Berl, et al, 1976; Fiorina and Plott, 1978). Some recent experimentation, however, hints at possible problems in a finite alternative setting. Isaac and Plott (1978) report several such experiments in which subjects fail to adopt a core, although their experimental design uses a particular procedure of chairman control that might account for these results. Elsewhere (1979b) we report a series of vote trading experiments in which the core's success rate is less than fifty percent. In this essay we present some additional experimental evidence to suggest that committee choice in simple majority rule games is not dictated solely by whether or not a Condorcet (core) point exists. We conclude that, in the experimental context of open and free discussion, the performance of the core is affected by the structure of alternative space, and also by the structure of the perceived dominance relation beneath the core in the social ordering

Links between parental life histories of wild salmon and the telomere lengths of their offspring

The importance of parental contributions to offspring development and subsequent performance is self-evident at a genomic level; however, parents can also affect offspring fitness by indirect genetic and environmental routes. The life history strategy that an individual adopts will be influenced by both genes and environment; and this may have important consequences for offspring. Recent research has linked telomere dynamics (i.e. telomere length and loss) in early life to future viability and longevity. Moreover, a number of studies have reported a heritable component to telomere length across a range of vertebrates, though the effects of other parental contribution pathways have been far less studied. By using wild Atlantic salmon with different parental life histories in an experimental split-brood IVF mating design and rearing the resulting families under standardised conditions, we show that there can be significant links between parental life history and offspring telomere length (studied at the embryo and fry stage). Maternal life history traits, in particular egg size, were most strongly related to offspring telomere length at the embryonic stage, but then became weaker through development. In contrast, paternal life history traits, such as the father's growth rate in early life, had a greater association in the later stages of offspring development. However, offspring telomere length was not significantly related to either maternal or paternal age at reproduction, nor to paternal sperm telomere length. This study demonstrates both the complexity and the importance of parental factors that can influence telomere length in early life

Shorter juvenile telomere length is associated with higher survival to spawning in migratory Atlantic salmon

The risk of mortality associated with a long-distance migration will depend on an animal's physiological state, as well as the prevailing ecological conditions. Here we assess whether juvenile telomere length, which in endotherms has been shown to be a biomarker of physiological state and expected lifespan, predicts whether wild Atlantic salmon Salmo salar successfully complete their marine migration. Over 1800 juvenile fish were trapped, measured, PIT-tagged and a tissue biopsy taken when migrating as juveniles down-river towards the sea. Survivors of the marine phase of the life cycle were then re-trapped and re-sampled when returning to the river to spawn as sexually mature adults, 1.5-2.5 years later. Most individuals experienced a reduction in telomere length during the marine migratory phase of their life cycle. While the relative rate of telomere loss was greater in males than females, telomere loss was unrelated to growth at sea. Contrary to expectations, salmon that had the shortest telomeres at the time of the outward migration had the greatest probability of surviving through to the return migration. This effect, independent of body size, may indicate a trade-off between investment in readiness for marine life (which favours high glucocorticoid levels, known to increase telomere attrition in other vertebrate species) and investment in telomere maintenance. Survival was also significantly influenced by the seasonal timing of outward migration, with the fish migrating downstream earliest in the spring having the highest probability of return. This study reveals that telomere length is associated with survival, although in ways that contrast with patterns seen in endotherms. This illustrates that while telomeres may be universally important for chromosome protection, the potential for telomere dynamics to predict performance may vary across taxa

Detector arrays for low-background space infrared astronomy

The status of development and characterization tests of integrated infrared detector array technology for astronomy applications is described. The devices under development include intrinsic, extrinsic silicon, and extrinsic germanium detectors, with hybrid silicon multiplexers. Laboratory test results and successful astronomy imagery have established the usefulness of integrated arrays in low-background astronomy applications

The Status and Distribution of Trumpeter Swans (Cygnus buccinator) in the Yukon

The presence of a breeding population of Trumpeter Swans (Cygnus buccinator) in the Yukon is established from previous summer records of swans and by data from extensive aerial surveys. The population is estimated to number about 50 pairs, with at least 32 pairs found near Toobally Lakes in southeast Yukon Territory. Habitat, nesting, population, and migration data are presented for the Toobally Lakes population. The habitat is characterized by rolling hills interspersed with water bodies from 5 ha to 250 ha in the area, frequently influenced by beaver. Nesting and cygnet development appeared to be later than those reported for Alaska or Alberta. Cygnet production was 19 young by August 1980 and 26 young by July 1981. Band returns indicate that part of the Yukon population winters in Montana. Recommendations for habitat protection are made.Key words: Trumpeter Swans, Cygnus buccinator, Yukon, breeding, distribution, migration, habitatMots clés: Cygne trompette, Cygnus buccinator, Yukon, nidification, distribution, migration, habita