Neighboring tidewater glaciers often exhibit asynchronous dynamic behavior, despite relatively uniform regional atmospheric and oceanic forcings. This variability may be controlled by a combination of local factors, including glacier and fjord geometry, fjord heat content and circulation, and glacier surface melt. In order to characterize and understand contrasts in adjacent tidewater glacier and fjord dynamics, we made coincident ice-ocean-atmosphere observations at high temporal resolution (minutes to weeks) within a 10 000 km2 area near Uummannaq, Greenland. Water column velocity, temperature and salinity measurements reveal systematic differences in neighboring fjords that imply contrasting circulation patterns. The observed ocean velocity and hydrography, combined with numerical modeling, suggest that subglacial discharge plays a major role in setting fjord conditions. In addition, satellite remote sensing of seasonal ice flow speed and terminus position reveal both speedup and slow-down in response to melt, as well as differences in calving style among the neighboring glaciers. Glacier force budgets and modeling also point toward subglacial discharge as a key factor in glacier behavior. For the studied region, individual glacier and fjord geometry modulate subglacial discharge, which leads to contrasts in both fjord and glacier dynamics.

Ritenbenk/Innaq in Disko Bay is the only remaining Thick-billed Murre colony in central West Greenland. It has declined by 72% since 1980 and now (2012) holds c.1,100 breeding pairs. In 2005–2006 and 2011–2012, a number of studies were carried out in this colony to improve our understanding of the population decline and its causes. Hunting has previously been identified as a problem for the colony, but local breeding conditions have never been studied and the non-breeding distribution was known only from ringing. Our studies showed that breeding success was moderate to good in the Ritenbenk colony and apparently not limited by food availability. The impact of gull predation was more uncertain, but seemed limited in our study plot. In contrast, estimates of maximum sustainable harvest levels showed that hunting, including illegal activities, was and still is too high and probably can explain much of the population decline. It is puzzling though, that the steepest population decline was observed within the most recent decade when the harvest level was markedly reduced. This may indicate that something else besides hunting mortality affects the colony. The winter distribution of the Ritenbenk birds includes areas in the central North Atlantic, such as the waters around South Greenland, where conditions have been identified as potentially deteriorating due to pronounced oceanographic changes. The potential impact on the Ritenbenk colony, as well as other colonies in the North Atlantic, needs to be studied further.

We study the dynamics of semigroups of Möbius transformations on the Riemann sphere, especially their Julia sets and attractors. This theory relates to the dynamics of rational functions, rational semigroups, and Möbius groups and we compare and contrast these theories. We particularly examine Caruso’s family of Möbius semigroups, based on a random dynamics variant of the Fibonacci sequence.

Let X be a non-compact surface (or 2-orbifold) of finite type with a metric of strictly negative curvature. Using an ideal tiling of the universal cover of X, we give a symbolic description of the recurrent geodesics on X. This extends Series’s method of coding geodesics on the modular surface.

Interaction of therapeutic drugs with a series of different biopathological substrates of psychosis might be expected to generate a series of different response patterns. Herein the authors suggest that multi-modal response patterns following lithium and neuroleptic treatment of psychotic patients may aid in resolving the heterogeneity of psychotic disorders and lead to a new nosology of the psychoses.

The foreign property rule (FPR) requires that no more than 30% of the assets held in tax-deferred retirement savings accounts be foreign property. The FPR is supposed to increase the value of the dollar and reduce its volatility and decrease the cost of capital and promote investment in Canada as well as decrease the extent of inequality inherent in these plans. On the basis of evidence from the easing of this regulation from 20% to 30% over the period 2001/02 we find that it accomplishes none of these objectives. There was no measurable impact on the exchange rate predicted from the Bank of Canada's forecasting equation; the capital outflow from the change amounted to no more than two days trade in the foreign exchange market over the period 2000/01; Canada's equity markets did significantly better internationally when the FPR was eased than in the prior two-year period. Finally, closer inspection reveals that the rule exacerbates income inequality by imposing the largest costs on lower middle-income groups. We estimate that the increase in the FPR from 20% to 30% increased Canadians expected income by between 500 million and one billion dollars annually by permitting greater portfolio diversification. The complete removal of the FPR would increase income by an estimated additional 1.5 billion to 3 billion dollars annually.

The electronic properties of arrays and isolated magnetite nanocrystals were studied using tunneling spectroscopy. Macroscopic tunnel junctions were used to study stacked arrays of the nanocrystals. The temperature dependent resistance measurements showed an abrupt increase of the resistance around 100 K, attributed to the Verwey metal-insulator transition, while the current-voltage characteristics exhibit a sharp transition from an insulator gap to a peak in the density of states near the Fermi energy. This conductance peak was sensitive to in-plane magnetic field showing large magnetoresistance. The tunneling spectra obtained on isolated particles using a Scanning Tunneling Microscope exhibit a gap-like structure below the transition temperature that gradually disappeared with increasing temperature, ending with a small peak structure around zero bias.

We develop a variant of the Taylor approximation approach to the periodic points of systems of contraction mappings [Rl] that does not invoke compactness conditions. Our presentation is simpler, in that certain steps are bypassed and only one basic estimate is used (Lemma 1). We also study the distribution of the discrete spectrum for the relevant transfer operators (Proposition 2).

We regret to say that there is an error in the proof of theorem 1 of [F]. The algebras E*(U), E*(S) used there are not preserved by d, as claimed, save in the restricted case when U and S commute. A counterexample is the nilmanifold automorphism of [AA], Appendix 23. Thus the results of §1 and §2 are dubious, although the third section is unaffected.

We extend results of Bowen and Manning on systems with good symbolic dynamics. In particular we identify the class of dynamical systems that admit Markov partitions. For these systems the Manning-Bowen method of counting periodic points is explained in terms of topological coincidence numbers. We show, in particular, that an expansive system with a finite cover by rectangles has a rational zeta function.

The cohomology action of an Anosov diffeomorphism on a nilmanifold resembles that of a Cartesian product map. Corresponding results hold for infranilmanifolds, giving an invariant bigrading of the cohomology and a fourfold symmetry that extends Poincaré duality. Holonomy invariant cocycles are applied to the action on first cohomology.

We study which algebraic integers λ ≥ l arise as the growth rate of a mapping class of a surface and give conditions that are necessary and perhaps sufficient. Flow equivalence and twisted Lefschetz zeta functions are used to generate families of λ's. Examples and open problems are included

In response to a question of Newhouse, we show that in many cases an Anosov automorphism can be uniformly approximated by a Smale diffeomorphism of the same topological entropy. We conjecture this can be done whenever the automorphism is sufficiently hyperbolic.

A three-dimensional example is given that suggests this approximation is not always possible.

We determine when a polynomial is the reduced zeta function of a basic set of a Smale diffeomorphism of a compact surface.

The concepts of speckle interferometry as developed by Labeyrie, and of speckle imagery as formulated by Knox and Thompson are analyzed for dependence on field-of-view size. The preliminary analysis, assuming isoplanatism rederives the results of Korff, and derives the result previously inferred by Knox and Thompson from computer simulation, that allowable spatial frequency separation for difference of phase shift determination must be less than r0/λ When the assumption of isoplanatism is dropped, results are obtained for the expected object power spectrum in speckle interferometry and for the expected bispectrum in speckle imagery, showing the dependence on angular spread for an object consisting of a pair of point sources. An angle, ϑ, is defined (in terms of an integral over the strength of turbulence distribution along the propagation path), which bounds the range within which there are no significant anisoplanatism effects. It is noted that the effect of anisoplanatism is not to attenuate the information bearing signal but rather to impose incorrect information on the signal. Thus anisoplanatism can result in incorrect conclusions with no indication that there is a problem.