Showing papers by "Queen's University published in 1982"

The Theory of Risk Homeostasis: Implications for Safety and Health

Abstract: No strategy for countermeasure design or future directions of research in the areas of human behavior which leads to traffic accidents or lifestyle-related diseases can be rationally developed without an acceptable working theory of human behavior in these domains. For this purpose, an attempt has been made to conceptually integrate the available evidence with respect to the role of human behavior in the causation of road accidents. From this integrative effort it would seem that the accident rate is ultimately dependent on one factor only, the target level of risk in the population concerned which acts as the reference variable in a homeostatic process relating accident rate to human motivation. Various policy tactics for the purpose of modifying this target level of risk have been pointed out and the theory of risk homeostasis has been speculatively extended to the areas of lifestyle-dependent morbidity and mortality.

Tectonic accretion and the origin of the two major metamorphic and plutonic welts in the Canadian Cordillera

Abstract: The Omineca Crystalline Belt and Coast Plutonic Complex are the two major regional tectonic welts in the Canadian Cordillera in which were concentrated intense deformation, regional metamorphism, granitic magmatism, uplift, and erosion. The welts, which formerly were thought to result from subduction of Pacific Ocean lithosphere beneath the western edge of North America, can now be viewed partly as the result of tectonic overlap and/or compressional thickening of crustal rocks during collisions between North America and two large, composite, allochthonous terranes that were accreted to its ancient western margin. The inner composite terrane, Terrane I, includes four smaller terranes that apparently were together by the end of Triassic time. The outer composite terrane, Terrane II, comprises two terranes, amalgamated by Late Jurassic time. The Omineca Crystalline Belt formed mainly from mid-Jurassic time onward, during and following the collision of Terrane I with North America. This belt straddles the zone of overlap of autochthonous and allochthonous terranes, and its characteristic metamorphism and structure are superimposed on both. The Coast Plutonic Complex formed mainly in Cretaceous to early Tertiary time during and following the attachment of Terrane II to the new, Jurassic, continental margin. It lies along the boundary of Terrane I and Terrane II and involves elements of both terranes. The collisions took place within the overall setting of the North American plate moving relatively westward into various Pacific plates from Jurassic time onward and in conjunction with subduction of Pacific Ocean lithosphere.

The place of teachers' beliefs in research on teacher thinking and decision making, and an alternative methodology

Abstract: Recent research on teacher thinking and decision making is reviewed, together with the models that gave rise to this work, to show first that scant and insufficient attention has been given to the content of teachers' thinking, specifically their beliefs and principles, and second that because of this, the inferences made in these studies are flawed by assumptions, especially by the assumption that teachers and researchers share perceptions and so understand language identically. An alternative methodology for acquiring an understanding of teachers' beliefs and principles is described and illustrated with a case study. This methodology is an adaptation of Kelly's Repertory Grid Technique.

An economic theory of central places

Abstract: is not really a theory of spatial economic behaviour. Instead, it is a series of brilliant conjectures about the locational configurations that will result from such behaviour. The brilliance of these conjectures is illustrated by the successful applications of the theory to such diverse phenomena as the locational patterns of retailing activity in cities and of service centres in rural areas, the size distribution of cities and the diffusion of information and diseases.' In this paper, we outline an economic model of central places.2 Our theorising has two distinct purposes. First, we wish to begin the development of a theory of central places that is based on maximising behaviour of economic agents. Any theory of economic behaviour from which central places can be derived is necessarily both difficult and cumbersome. Non-convexities in the activities of buying and selling drive the model, and thus non-differentiabilities and discontinuities abound. As one seeks more generality in such circumstances, difficulties multiply rapidly. In order to begin the job, we have used assumptions that are specific and sometimes even crude. The second purpose of our theorising is to illustrate the limitations of current central place theory by providing counter examples to some propositions commonly accepted to follow from it. For this purpose we need not worry about lack of generality in any of our counter examples. Of course we are not solely concerned to refute accepted generalisations. By doing so, we hope to make alternative possibilities apparent. What we hope to attain, therefore, is a theoretical development inspired by the extremely fruitful conjectures of existing central place theory.

American Industry: Structure, Conduct, Performance

Abstract: 1. The Business Sector and Its Organization. 2. Elements of Market Structure. 3. The Large Corporation. 4. Market Conduct. 5. Market Performance. 6. The Promotion of Competition and the Control of Monopoly. 7. Public Policy: Regulation and Public Enterprise. Selected Readings. Index.

The ATP 30-a scale for measuring medical students' attitudes to psychiatry.

Abstract: The development and validation of a thirty item, Likert-type scale designed to measure medical students' attitudes to psychiatry-the ATP-30 (Attitudes Toward Psychiatry-30 items)-are described. We had hoped to demonstrate that 'attitude to psychiatry' was not a unitary matter but an amalgam of attitudes to a number of things to do with psychiatric practice. This hope was not fulfilled, as a unitary dimension was obtained. A positive change in the attitudes of students toward psychiatry was demonstrated in third and fourth medical year students in relation to exposure to psychiatry. Such a change was not demonstrable in two classes of occupational therapy students exposed to a course in psychiatry. The reasons for this difference between medical students and occupational therapy students are discussed-there possibly being important implications here for psychiatric curriculum planning in medical school. Lastly, we have demonstrated that the positive change in attitudes amongst medical students was transient rather than lasting-a matter which most studies of attitude change do not address. In spite of the apparent impermanence of the positive change in attitudes among medical students, there are a number of possible used to a scale such as the ATP-30, and these are discussed.

DC conduvtivity of V2O5TeO2 glasses

Abstract: The dc conductivity of semiconducting vanadium tellurite glasses of compositions in the range 50 to 80 mol% V2O5 has been measured in the temperature region 77 to 400 K. Measurements have been made on annealed samples at different annealing temperatures. Annealing the samples at temperature of about 250°C causes the appearance of a complex crystalline phase resulting in an increase of conductivity. Results are reported for amorphous samples of different compositions. The conductivity of tellurite glasses is slightly higher than the corresponding composition of phosphate glasses, but the general trend of the increase of conductivity and decrease of high temperature activation energy with increasing V2O5 content is similar in the two systems. The data have been analysed in the light of existing models of polaronic hopping conduction. A definite conclusion about the mechanics of conduction (adiabatic or nonadiabatic) is difficult in the absence of a precise knowledge of the characteristic phonon frequency v0. Adiabatic hopping is indicated for v0∼1011 Hz, however this value leads to unreasonably low value for the Debye temperature θD, and higher values for v0∼1013 hz satifiies the conditions for nonadiabatic hopping which appears to be the likely mechanism of conduction in V2O5TeO2 glasses. The low temperature data (< 100 K) can be fitted to Mott's variable range hopping, which when combined with ac conductivity data gives reasonable values of α, but a high value for the disorder energy.

Archean abiogenic and probable biogenic structures associated with mineralized hydrothermal vent systems and regional metasomatism, with implications for greenstone belt studies

Abstract: Abiogenic structures, formed by fluid emission in subaerial mud pools and nearby stromatolites, from stratigraphically related carbonate sediments, occur in the southern part of the approximately 3.3 to 3.5-b.y.-old Barberton greenstone belt. The mud pool structures are associated with ferruginous shales, banded iron-formations, and in places barite deposits; they relate stratigraphically to transgressive pods of ironstone. The pods probably represent buried, mineralized hydrothermal channels and chimneys. Soft sediment deformation structures adjacent to these pods suggest fossil fluid circulation patterns in the sediments with horizontal flow over distances greater than 300 m and vertical motions an order of magnitude less. Associated metasomatism has significantly altered the original chemistry of the host rocks on a regional scale, prior to 13.8 b.y. This is described with specific reference to silicification. Silicification patterns in the igneous rocks underlying the sediments also indicate fluid circulation patterns an order of magnitude greater than those in the sediments. Thin but regionally extensive and originally horizontal alteration planes were probably zones of high fluid pressure along which large-scale, gravity-induced mass transportations occurred. Such transportations greatly influenced the subsurface mineral precipitation and the surface geologic processes within the extensive area of hydrothermal activity, in which the inferred high geothermal gradient was probably related to shallow-level igneous activity. At least minor mineralization, including local gold concentration several orders of magnitude greater than that found in average crustal rocks (e.g., ppb to ppm), occurred simultaneously with these processes of metasomatism during sedimentation, igneous activity, and tectonism within the belt, and prior to the intrusion of the greenstone belt by surrounding granitoids.

The biology of the human natural killer cell

Abstract: Natural killer (NK) cells in the human are a population of large granular lymphocytes (LGL) with at least one unique surface antigen not expressed on cells of other lineages. NK-target-cell interaction appears to involve carbohydrate recognition and, following binding, the NK cells are induced to generate O2−, transmethylate membrane phospholipids, and activate phospholipase A2. Some or all of these activities trigger a cascade of events which ultimately leads to the secretion of a substance toxic to the target cell. A variety of genes controls various steps in this cytolytic pathway. There is a good deal of evidence in the mouse, and some in the human, that NK cells play a role in host surveillance against tumor development, resistance to viral infections, and, possibly, hematopoietic regulation.

The Western Canada sedimentary basin

Abstract: The Western Canada Sedimentary Basin, a simple northeasterly tapering wedge of sedimentary rocks more than 6 km thick, extends southwest from the Canadian Shield into the Cordilleran foreland thrust belt. Its internal structure and the lateral variations in its shape reflect a long and complex history of development involving a foreland basin that was superimposed on a cratonic platform and continental terrace wedge. This history, which is inextricably linked to the evolution of the Canadian Cordillera, can be outlined succinctly with reference to the unconformity-bounded transgressive-regressive stratigraphic sequences established by Sloss (Bull. geol. Soc. Am. 74, 93 (1963)), each of which has a distinctive character in Western Canada. The continental terrace wedge was established with the deposition of the Proterozoic Purcell (1500-1350 Ma) and Windermere (850-600 Ma) sequences, but the first record of the platformal phase is the early Palaeozoic transgressive onlap of the early Proterozoic (> 1750 Ma) crystalline basement by the Sauk sequence. Early Palaeozoic subsidence of the margin of the craton may have been due to cooling of the lithosphere after renewed stretching at the ancient rifted western margin of the Precambrian craton, and to isostatic flexure of the lithosphere under the weight of the sediment that had accumulated at the margin in the oceanward prograding continental terrace wedge. During a subsequent Middle Ordovician to Middle Jurassic phase, the cratonic platform became differentiated into an intersecting network of epeirogenic arches with intervening basins. Development of the basins was as much a result of erosion and uplift of the arches between transgressive-regressive cycles as it was a result of differential subsidence of the basins during the cycles. The cause of the long (> 300 Ma) episode of intermittent epeirogenic movements that produced the basins and arches is a major unsolved problem. The foreland basin developed in two stages, in Middle Jurassic to early Cretaceous and late Cretaceous to Palaeocene time, as a result of collisions between North America and two pieces of a tectonic collage of oceanic terranes that were accreted to its western margin. During these two collisions, the continental terrace wedge, which had accumulated outboard from the rifted margin of the continental craton, was compressed and displaced over the western margin of the craton. Part of the supracrustal cover was scraped off the craton and accreted to the overriding mass to form a wedge of imbricate thrust fault slices that was tectonically prograded over the margin of the continental craton. Isostatic flexure of the continental lithosphere in response to the tectonic loading imposed on it by the displaced continental terrace wedge and the accretionary wedge of thrust slices produced the migrating moat in which the outwash of clastic detritus from the evolving thrust belt was trapped to form the foreland basin. The Palaeohelikian flat-lying unmetamorphosed basin remnants high on the Craton show that the Craton was established long before the commencement of the Phanerozoic cycle of basin development examined in this paper. The first significant event in this history was the development, over attenuated crust, of an Atlantic type down-to-ocean faulted margin in the Neohelikian, upon which was deposited a great wedge of clastic sediments across the structural grain of the Archaean platform, followed after a gap of 500 Ma by renewed faulting and subsidence and further loading in Hadrynian time. The subsidence of the continental margin as a result of this imposed load and thermal contraction extended far into the craton and set the stage for the first cycle of deposition represented by the Sauk sequence. Sauk sequence. The Sauk sequence records progressive onlap with the Upper Cambrian strata extending high on the western side of the craton and the depositional strike running northwesterly, parallel to the probable old continental margin. There is a notable lack of arches or isolated basins. This initial sequence is dominated by clastic sediments from the shield. Tippecanoe sequence. Arches interrupted the linear depositional pattern. Marked sedimentary attenuation over highs created a relative thickening in the area of the Williston Basin. This sequence shows thin seams of fine sand and silt suggesting episodic uplift of the burgeoning arches, but the dominance of carbonate rock indicates that they were for the most part covered. The lack of an onlapping relation, and widespread inundation of the craton indicate a very rapid transgression. Like the Cambrian seas, those of the Ordovician and Silurian transgressed from the western margin. Kaskaskia sequence. The strongly developed pre-Devonian arches surrounding and segmenting the Devonian depositional area resulted in a transgression of over 3000 km from the northwest, rather than the west, over a tectonically disturbed and eroded surface, resulting in complex facies patterns. The Mississippian seas covered almost as large an area as those of the Ordovician, onlapping completely the Western Alberta and Peace River arches. Arches in the southern and western part of the Williston Basin continued to grow into late Kaskaskia time, creating sills with salt deposits in the regressive part of the sequence that culminated with a clastic assemblage derived from the flanking arches. Absaroka sequence. The Sweetgrass Arch isolated the Alberta Basin from the Williston Basin for the first time. These opened to the southwest and west respectively. The Williston Basin had a dominant red bed-evaporite assemblage, the Alberta Basin a marine clastic assemblage. This interval is characterized by periods of non-deposition and erosion, with depositional limits of each system indicating much less encroachment on to the craton, which appears to have progressively increased its rate of dip to the west. The progressively increased rate of westward thickening from the Sauk to Kaskaskia to Absaroka in the undisturbed part of the basin also suggests an increasing westward tilt or subsidence of the basin margin. Zuni sequence. The Zuni reflects the late Jurassic orogenic activity in the west. The convergence of allochthonous terranes with the continental margin resulted in the thrusting of the marginal deposits eastward, tectonically loading the lithosphere and providing the provenance for the continental clastic sediment that filled the foredeep which formed in response to the loading. The continental sediment spread across the basin with marine seaways to the north and south that gradually advanced to join together to form a seaway extending from the Arctic to the Gulf of Mexico in mid-Cretaceous time. A second plate convergence resulted in further tectonic thickening with thrusting extending further east, cannibalizing previously formed deposits and generating a second sequence of terrestrial sediments that covered the entire basin again in the late Cretaceous and Palaeocene. Notably absent during the Zuni was the influence of arches that had previously segmented the basin. Also absent are carbonates and evaporites. Instead the basin fill was entirely of clastic sediments. The present structural configuration of the basin was established during this period as the foredeep encroached onto the craton.

Atrial Natriuretic Factor of the Rat Heart. Studies on Isolation and Properties

Abstract: Studies on a chemical extraction and purification procedures are described for rat atrial natriuretic factor. This factor—first detected by injection of crude rat atrial heart muscle homogenates—induces a powerful diuretic and natriuretic response when injected into nondiuretic assay rats. Studies on the properties of purified natriuretic factor suggest that it is of a proteinaceous nature. It is efficiently extracted by dilute acetic acid, readily degraded by protease, and recoverable after gel filtration at a fractionation range corresponding to less than 6000 daltons. Dose-response studies show that at maximal doses the response is a 10- to 15-fold increase in urine output and a 30- to 40-fold increase in urinary sodium excretion. These responses are characteristically of rapid onset (1-2 min) and decay (10-15 min).

Contractile properties of the human triceps surae with some observations on the effects of temperature and exercise.

Abstract: The contractile properties of the triceps of five healthy male subjects (mean age 22 years) during electrically stimulated and voluntary isometric muscle contractions were investigated and some observations made on the effects of muscle heating and cooling and dynamic exercise. The times to peak twitch tension (TPT) and half relaxation time (1/2RT) were 111 +/- 20 ms and 83 +/- 13 ms respectively. Heating and prior exercise decreased, and cooling severely prolonged, TPT and 1/2RT. Exercise and heating had no effect on supramaximal twitch tension (Pt0) but cooling the muscle to a temperature of 24.3 degrees C reduced it by 52%. The effects of repetitive stimuli on Pt0 were dependent on frequency; at 0.2 Hz potentiation was observed but at 2 Hz, Pt0 was depressed under control conditions. Heating had no effect on these responses but cooling reversed the 2 Hz and abolished 0.2 Hz response. Post-tetanic potentiation of the twitch was observed under all conditions of measurement. At submaximal stimulation voltages, heating and exercise enhanced twitch and tetanic tensions, but at supramaximal voltages heating reduced tetanic tension (P0) at 10 Hz (by 115 N), though not at 20 Hz. Exercise decreased P0 at both frequencies of stimulation. Cooling significantly reduced the maximal voluntary contraction and P0 at 20 Hz. At submaximal voltages, heating enhanced and cooling severely depressed tetanic tensions at high frequency (100 Hz) stimulation. A 2-min fatigue test was unaffected by heating but cooling reduced force generation at the onset of, and the decline of force during, the test. It was concluded that studies of the contractile properties of human muscle in vivo should be based on supramaximal stimulation, and that temperature and prior exercise should be carefully standardised in order to obtain reliable and meaningful results.

Implementing the unrelated product strategy

Abstract: There has been considerable debate over the viability of the unrelated product, or conglomerate strategy. The financial arguments for and against its viability are well known. However, the administrative imperatives for its successful implementation have not been well investigated. The paper argues that there are a number of critical administrative contingencies for successful implementation of this strategy which only a few unrelated product firms have recognized. These concern policies dealing with acquisition, divestment, portfolio structure, management and organization. The paper discusses each in turn, describing specific instances of success and failure to illustrate the major points of the argument.

The catalytic cracking of cumene

Abstract: Science, by its very nature, aspires to the orderly arrangement of knowledge in a way which will allow predictive interpolation and even cautious extrapolation into unstudied regions of performance on the basis of known data. So it is that in the study of kinetics many sophisticated attempts have been made to calculate the rate parameters for some of the simplest gas-phase reactions from basic physical measurements. Most such attempts have so far ended in failure, and kinetics remains basically an experimental science.

Studies of human natural killer cells. I. In vivo parameters affecting normal cytotoxic function.

Abstract: The results of natural killer cell (NK) studies on 539 normal healthy donors tested from once to 213 times over a seven-year time span have been presented. NK activity did not vary with donor blood group, Rh type or (in a small sample) HLA type. There was a slight but significant increase in NK activity from birth to adulthood, and between males an females. The male/female difference was present at birth and persisted through adulthood. The relative NK activity of individual donors tested repeatedly over many years was remarkably consistent in spite of variability in the absolute cytotoxicity observed. The expression of NK data in terms of relative NK was found to be superior to other methods, and the values obtained were found to be independent of the NK-sensitive target cell used. Although age and sex differences in NK activity are slight, their existence should be considered when studies of NK activity in patients are analysed.

insect vitellins: Identification, purification, and characterization from eight orders

Abstract: Vitellins were identified, purified, and analyzed from insects representing eight orders. The structures and polypeptide constituents of vitellins of Hyalophora cecropia, Tenebrio molitor, Rhodnius prolixus, Forficula auricularia, Periplaneta americana, and a mayfly were found to have common features. The native proteins had Mr of 385,000–470,000 (385–470 K) and were composed of high (100–180 K) and low (47–84 K) molecular weight polypeptides in equimolar proportions. The vitellins of Apis mellifera, a sphecid wasp, and Aedes aegypti, however, had lower Mr (200–350 K) and were composed of only large polypeptides (170–190 K). The higher Diptera form a distinct third group with vitellins made up entirely of small polypeptides of about 50 K.

The role of vibration in the tactual perception of roughness

Abstract: Katz (1925) has argued that the sense of vibration underlies the tactual perception of roughness. However, Taylor and Lederman (1975) have suggested that vibration serves only to prevent the cessation of mechanoreceptor activity. In an experimental evaluation of these positions, it is shown that, although prior (selective) adaptation of the fingertip strongly affects the perceived magnitude of supraliminal vibrotactile signals, it fails to alter the perceived roughness of metal gratings. The results thus favor the Taylor and Lederman position. The paper also speculates on roughness coding by the mechanoreceptor populations present in glabrous skin of the human hand.

Moral Hazard and Optimal Commodity Taxation

Abstract: The central result of this paper is that when moral hazard is present, shadow prices in general differ from market prices. To remedy this market failure, the government should introduce differential commodity taxation. Moral hazard causes people to take too little care to prevent accidents. The corresponding deadweight loss can be reduced by subsidizing (taxing) those goods the consumption of which encourages (discourages) accident avoidance. At the constrained optimum, the sum of the deadweight losses and differential commodity taxation is minimized. Policy implications are derived and discussed.

Some Non-Nested Hypothesis Tests and the Relations Among Them

Abstract: In this paper we discuss several statistical techniques which may be used to test the validity of a possibly non-linear and multivariate regression model, using the information provided by estimating one or more alternative models on the same set of data. We first exposit, from a different perspective, the tests proposed by us in Davidson and MacKinnon (1981a), and discuss modified versions of these tests and extensions of them to the multivariate case. We then prove that all these tests, and also the tests previously proposed by Pesaran (1974) and Pesaran and Deaton (1978), based on the work of Cox (1961, 1962), are asymptotically equivalent under certain conditions. Finally, we present the results of a sampling experiment which shows that different tests can behave quite differently in small samples.

A Structured Model for Rail Line Simulation and Optimization

Abstract: A general purpose model of a railway line is presented. This model is based on an algebraic structure which describes the movement of trains over the line. This structure permits an arbitrary number of different trains with differing speeds and priorities to be dispatched over any line configuration including single or multiple tracks and sidings with restricted switching or cross-overs. Both optimization procedures and simulation models of the line can be implemented using this framework. The problem of line blockage at high traffic intensities is discussed, and conditions are given to ensure this does not occur. Computationally simple feasibility tests are presented together with a behaviorally based dispatching model. The model is implemented as a general purpose discrete event simulation model in which different dispatch goals or criteria can easily be included. Details of a validation example involving very high traffic intensity over a typical Canadian rail line are presented.

Oxygen intermediates are triggered early in the cytolytic pathway of human NK cells

Abstract: The mechanism of tumour cell destruction by natural killer (NK) cells or other lymphocytes is not understood. NK cells appear to represent a primitive anti-tumour surveillance system more analogous to macrophages than lymphocytes. Free oxygen radicals (O-2, OH) and H2O2 are thought to be involved in cell destruction by macrophages and therefore we looked for similar cytocidal intermediates of oxygen in NK cells. These highly reactive molecular species can easily be detected in the presence of luminol by the emission of light. We show here that highly enriched human NK cells respond to NK-sensitive but not NK-insensitive tumour cells with a rapid burst of oxygen metabolites as detected both by chemiluminescence and cytochrome c reduction. Agents which can prevent chemiluminescence and cytochrome c reduction, such as superoxide dismutase (SOD), reduced NK-mediated cytolysis and agents which increased chemiluminescence, such as interferon, also increased NK-mediated cytolysis. These results suggest that the production of oxygen species may be the earliest event to occur in the NK cell following tumour cell contact, and these products are involved in NK-mediated cytolysis.

Breeding synchrony in the lesser snow goose (anser caerulescens caerulescens): i. genetic and environmental components of hatch date variability and their effects on hatch synchrony.

Abstract: Synchronized breeding is characteristic of many colonial species, and has been studied in both temperate and subtropical populations (Smith, 1943; Coulson and White, 1956; Hailman, 1964; Patterson, 1965; Harris, 1966). Breeding synchrony refers to the tendency of individuals to carry out some stage of the reproductive cycle (e.g., courtship, nest establishment, laying, etc.) simultaneously with other members of the colony. The close association between the spatial (coloniality) and temporal (synchrony) clustering of individuals suggests that for some species, the evolution of synchrony should not be considered independent of the evolution of coloniality (Gochfeld, 1980). Synchrony may be adaptive or nonadaptive. Several researchers (e.g., Lack, 1954; Brown, 1967; Nisbet, 1975) have suggested that a selective advantage accrues to those individuals capable of synchronizing their activities with neighboring pairs. This advantage may take the form of reduced predation pressure (Darling, 1938; Kruuk, 1964; Patterson, 1965; and see Robertson, 1973), or an increased efficiency of food localization (Emlen and Demong, 1975). Alternatively, the observed temporal clustering of individuals may result from selection pressures acting on the timing, rather than the synchronization, of reproduction. Populations in unpredictable environments may be highly synchronous simply because of the short time available for the production and rearing of young. In this case, synchronized breeding per se does not confer any selective advantage. Adaptive value can be inferred only if those individuals breeding asynchronously suffer a reduced fitness. Here, stabilizing selection would maintain synchrony in the population through the elimination of genotypes that breed asynchronously. For studies where genetic relationships are known, quantitative genetics provides several simple techniques for investigating the genetical basis of intraspecific variability. "Repeatability" and "heritability" estimates are two such approaches used to partition the total phenotypic. variance of a character into environmental and genetic components (Falconer, 1960). In this paper we consider the genetic and environmental determinants of hatch date variation in a colony of Lesser Snow Geese (Anser caerulescens caerulescens). A female's relative hatch date is the date relative to the colony mean on which her eggs hatch. It is the between-individual variation in relative hatch dates that determines the degree of hatching synchrony at the colony. In this discussion, we assess (1) annual variation in synchrony, (2) the proportion of the within-season variation in hatch date that arises from genetic differences between individuals, and (3) the degree to which hatch date variation, and hence, hatching synchrony, arises from variability in other components of the reproductive strategy. The evolution of hatching synchrony implies that (1) synchronous females have a greater reproductive fitness than asynchronous females, and (2) there is a genetic basis to inter-individual variability in relative hatch dates. Here we consider only the latter question. A discussion of the adaptive value of synchrony will be pre-