A Possible Advanced Hypsithermal Position of the Donjek Glacier

The history of the [Donjek] glacier from 1935 to the present is well documented photographically .... Documentation of the Hypsithermal and Wisconsin history of the glacier is less abundant. ... During the summer of 1970 the terminus area of the Donjek Glacier and the lower part of the glacier valley were investigated for evidence of its Hypsithermal position. No evidence was found in the valley occupied by the glacier to indicate that it had retreated back into the valley from the Donjek River Valley. The inclusion of 'Slims Soil' ... in the material of the Neoglacial moraine complex of the glacier indicates that there must have been some retreat up valley of the moraine position before the Neoglacial re-advance. Down valley from the Neoglacial moraines there is evidence for a relatively recent, probably Hypsithermal, ice marginal position. This evidence is in the form of a lateral moraine, terminal moraine remnants and the distribution and development of the Hypsithermal Slims Soil and volcanic ash. Unfortunately no material was found which could be dated by radiocarbon techniques to verify the age of the features. The glacial landforms are relatively easily identified when compared with the highly denuded forms which represent the pre-Neoglacial periods found elsewhere in the Donjek Valley. ... It is considered that there is evidence for a stable phase of the Donjek and Kluane Glaciers late in the Hypsithermal period. This position is down valley of the Neoglacial maximum position which contrasts with the documented situation in the Kaskawulsh Valley. Late in the Hypsithermal the glaciers retreated from this stable position, the Kluane Glacier retreating to a Neoglacial position 15 miles up valley and the Donjek Glacier apparently retreating only a short distance before readvancing to its Neoglacial maximum position

The University of the Arctic

... The advent of the Arctic Council renewed interest in northern post-secondary education and particularly in university education on the international scene. In early 1997, following informal discussions, the Arctic Council asked the Circumpolar Universities Association (CUA) to appoint a task force to report on the concept of a circumpolar university. The Arctic Council accepted the report in late 1997 and charged the CUA with forming a working group to develop a feasibility study. The working group consisted of representatives of the eight circumpolar countries and the indigenous peoples of the Arctic. The feasibility study was subsequently approved by the Ministerial Meeting of the Arctic Council in Iqaluit in 1998, and the working group became the Interim Council for the University of the Arctic, independent of the CUA. Canada is represented on the Interim Council by the Association of Canadian Universities for Northern Studies (I am the current President) and by Sally Ross, President of Yukon College, who represents the three northern colleges. The indigenous peoples' participants' the Sami Council, the Inuit Circumpolar Conference, and the Russian Association of Indigenous Peoples of the North - endorsed the concept of the University, provided that the full participation of indigenous people was ensured. ... The concept of the University is one of a university without walls. Programs are intended to be delivered through a range of distance learning technologies, through formal classroom settings at a number of locations in the circumpolar world and elsewhere (depending on the nature of the program component), and at field locations around the Arctic. In many locations, technical capacity will have to be upgraded to allow distance learning to be available not only in community centres, but in individual homes. This capacity is essential to maintain the strength of the community in northern cultures. However, mobility will also be promoted for some components of the programs, to bring together Arctic students and Southern students. ... One of the major challenges will be to develop information sources to support the curriculum. Since the focus of most extant texts is mid or low latitudes, it will be necessary to promote materials that emphasize the Arctic reality, which can readily be translated and produced in both hard copy and electronic formats. The University is therefore moving ahead with its mandate to provide undergraduate and postgraduate training with a focus on Northern issues and delivered in the North. The University is seeking full participation of northern people for its governance and instructional staff, while continuing to promote the integration of expertise in existing institutions

Hydrometeorology, Suspended Sediment and Conductivity in a Large Glacierized Basin, Slims River, Yukon Territory, Canada (1993-94)

The Slims River was monitored for global solar radiation, air temperature, discharge, suspended sediment, and dissolved load in 1993 and 1994. Peak seasonal discharge occurred late in the summer and reflects a typical glacierized basin hydrograph, with increased bare ice surfaces contributing strongly to discharge in July and August. Air temperature, rather than global solar radiation, was most strongly correlated with discharge in both years, but during sustained ablation, air temperature becomes a poor index of meltwater production. Precipitation was infrequent and of low magnitude. The variance in suspended sediment concentration could be explained only in part by discharge; frequent clockwise hysteresis and seasonal sediment concentration peaks unrelated to discharge variations also contributed to this variance. High concentrations of Ca2+ and Mg2+ in meltwaters reflect the lithological influence of carboniferous sedimentary rocks in the basin. Conductivity and individual cation concentrations decreased during both seasons and were inversely related to discharge. Diurnal conductivity amplitude was greatest during glacier melt, and frequent clockwise hysteresis was observed in both years.En 1993 et 1994, on a installé des appareils sur la rivière Slims pour mesurer le rayonnement solaire global, la température de l'air, le débit, les sédiments en suspension et la charge dissoute. Le débit saisonnier de pointe se produisait tard durant l'été et reflète l'hydrographe typique d'un bassin englacé, où les surfaces de glace vive plus étendues en juillet et en août contribuent fortement au débit. Au cours de ces deux années, la température de l'air plutôt que le rayonnement solaire global était très fortement corrélée au débit, mais la température de l'air devient un index médiocre de la production d'eau de fonte durant une période d'ablation intense. Les précipitations étaient rares et de faible intensité. La variance dans la concentration des sédiments en suspension pourrait s'expliquer en partie seulement par le débit; une hystérésis dextrorse fréquente et des pointes non reliées à la variation du débit dans la concentration saisonnière de sédiments contribuaient également à cette variance. De fortes concentrations de Ca2+ et de Mg2+ dans l'eau de fonte reflètent l'influence lithologique des roches sédimentaires carbonifères dans le bassin. La conductivité et la concentration en cations individuels diminuaient durant les deux saisons et étaient inversement reliées au débit. L'amplitude de conductivité diurne était la plus grande durant la fonte glaciaire, et on a observé une fréquente hystérésis dextrorse au cours des deux années

A characterization of Schauder frames which are near-Schauder bases

A basic problem of interest in connection with the study of Schauder frames in Banach spaces is that of characterizing those Schauder frames which can essentially be regarded as Schauder bases. In this paper, we give a solution to this problem using the notion of the minimal-associated sequence spaces and the minimal-associated reconstruction operators for Schauder frames. We prove that a Schauder frame is a near-Schauder basis if and only if the kernel of the minimal-associated reconstruction operator contains no copy of $c_0$. In particular, a Schauder frame of a Banach space with no copy of $c_0$ is a near-Schauder basis if and only if the minimal-associated sequence space contains no copy of $c_0$. In these cases, the minimal-associated reconstruction operator has a finite dimensional kernel and the dimension of the kernel is exactly the excess of the near-Schauder basis. Using these results, we make related applications on Besselian frames and near-Riesz bases.Comment: 12 page

Micromagnetic modelling and imaging of vortex/merons structures in an oxide | metal heterostructure

Using micromagnetic simulations, we have modelled the formation of imprinted merons and anti-merons in cobalt overlayers of different thickness (1-8 nm), stabilised by interfacial exchange with antiferromagnetic vortices in α-Fe2O3. Structures similar to those observed experimentally could be obtained with reasonable exchange parameters, also in the presence of surface roughness. We produce simulated meron/antimeron images by magnetic force microscopy (MFM) and nitrogen-vacancy (N-V) centre microscopy, and established signatures of these topological structures in different experimental configurations

Frameworks for logically classifying polynomial-time optimisation problems.

We show that a logical framework, based around a fragment of existential second-order logic formerly proposed by others so as to capture the class of polynomially-bounded P-optimisation problems, cannot hope to do so, under the assumption that P ≠ NP. We do this by exhibiting polynomially-bounded maximisation and minimisation problems that can be expressed in the framework but whose decision versions are NP-complete. We propose an alternative logical framework, based around inflationary fixed-point logic, and show that we can capture the above classes of optimisation problems. We use the inductive depth of an inflationary fixed-point as a means to describe the objective functions of the instances of our optimisation problems

The lithospheric mantle and lower crust-mantle relationships under Scotland: a xenolithic perspective

In the British Isles the majority of volcanic rocks containing upper mantle and lower crustal xenoliths occur in Scotland. Most of the occurrences are of Carboniferous–Permian age. This paper presents new data on the mineral chemistry of spinel lherzolite xenoliths from the five principal Scottish tectonic terranes. Compositional variations among the minerals emphasize the broad lateral heterogeneity of the subcontinental lithospheric mantle across the region. The remarkable range of Al2O3 v. CaO exhibited by the clinopyroxenes compared with data from other ‘xenolith provinces' emphasizes the extremely complex tectonomagmatic history of the Scottish lithosphere. The generalized age increase from southern and central Scotland to the Northern Highland and Hebridean terranes of the north and NW, with concomitant complexity of geological history, is reflected also by trace element and isotopic studies. Reaction relationships in lherzolites from the Hebridean Terrane, owing to pervasive metasomatism, involve secondary growth of sodic feldspar. This, and light REE enrichment of clinopyroxenes, points to involvement of a natro-carbonatitic melt. Most pyroxenitic xenoliths are inferred to form a basal crustal layer with a generally sharp discontinuity above the underlying (dominantly lherzolitic) mantle. A second discontinuity is inferred to separate these ultramafic cumulates from overlying, broadly cognate metagabbroic cumulates

New Insights into Uniformly Accelerated Detector in a Quantum Field

We obtained an exact solution for a uniformly accelerated Unruh-DeWitt detector interacting with a massless scalar field in (3+1) dimensions which enables us to study the entire evolution of the total system, from the initial transient to late-time steady state. We find that the Unruh effect as derived from time-dependent perturbation theory is valid only in the transient stage and is totally invalid for cases with proper acceleration smaller than the damping constant. We also found that, unlike in (1+1)D results, the (3+1)D uniformly accelerated Unruh-DeWitt detector in a steady state does emit a positive radiated power of quantum nature at late-times, but it is not connected to the thermal radiance experienced by the detector in the Unruh effect proper.Comment: 6 pages, invited talk given by SYL at the conference of International Association for Relativistic Dynamics (IARD), June 2006, Storrs, Connecticut, US