bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronological list of expeditions and historical events in northern Canada. V. 1790–1821
Authors: Cooke Alan , Holland Clive
Published: October 2009

During the period covered by this instalment of our list, the accomplishments of the North West Company, both in geographical exploration and in the realization of profits were great. It consolidated its position in the fur-rich Athabasca district and, with a few posts along Mackenzie River, began to draw in the furs of that immense territory. Its traders invaded not only the western part of Rupert's Land but even Hudson Bay itself. The Hudson's Bay Company rose only slowly to the challenge of its formidable rival, but, gradually, it began to adopt new policies and new techniques and to meet the North West Company on its own grounds and on its own terms. Finally, after a bitter struggle that was almost the destruction of both companies, the Hudson's Bay Company, in 1821, effectively absorbed the North West Company in a coalition that gave the older company greater strength than ever and a wider monopoly than Prince Rupert had thought of.
Radio-echo sounding in Antarctica, 1971–72
Authors: Evans S. , Drewry D. J. , Robin G. de Q.
Published: October 2009

A third field season in the joint research programme of the Scott Polar Research Institute (SPRI) and the United States National Science Foundation (NSF) was carried out between November 1971 and January 1972. For accounts of previous work in this programme, see Polar Record (1968); Evans and Smith, (1970); and Robin and others (1970). The personnel from SPRI working in the field during the past season were S. Evans, C. H. Harrison, D. J. Drewry, G. K. A. Oswald, M. R. Gorman, and (from the University of Gent and Expéditions Antarctiques Belges) H. Decleir. A. Clayton and J. Whittington of the SPRI staff assisted in data reduction.
Chronological list of expeditions and historical events in northern Canada. VII. 1846–54
Authors: Cook Alan , Holland Clive
Published: October 2009

This instalment of our list is dominated by the search for Sir John Franklin's missing North-west Passage expedition (see 1845–48). The search began in 1847 and continued intensively until 1854, when Dr John Rae finally found the first clues regarding the fate of the expedition. An important feature of the search was the large number of sledge expeditions, which set out from the searching ships in spring. By this means, many thousands of kilometres of new coastline were discovered in a relatively short period, mainly during the spring months of 1851 and 1853, and much of the Canadian Arctic archipelago, which was largely unknown before 1850, was added to the map. In nearly every case, the sledges were man-hauled by an officer and six or seven seamen. We are listing all of the searches for Franklin, as we listed all North-west Passage expeditions, including some that did not touch Canadian shores.
Nimbus satellite data for polar ice survey
Authors: Sissala John E. , Sabatini Romeo R. , Ackermann Hans J.
Published: October 2009

Repetitive surveillance by polar-orbiting meteorological satellites can monitor the distribution, variability, and behaviour of sea ice in both Arctic and Antarctic regions. This article reviews some of the applications of Nimbus satellite data to the polar regions. For a good review of applications of NOAA (formerly ESSA) satellite data to the polar regions, see Swithinbank (1969, 1970, 1971).
International transport routes in the Arctic
Authors: Armstrong Terence
Published: October 2009

Most of the highly populated regions of the world are in the middle latitudes of the northern hemisphere. The shortest routes between some of them (and they happen to be the most advanced technologically) lie across the Arctic regions. The possibility of using these routes on a commercial scale has become real only comparatively recently, as technology has found ways of dealing with the distances and the natural obstacles. The transport systems with significant international applications are by sea and air. Land transport, whether by road or rail, crosses few frontiers (north of the Arctic Circle, only into and within Scandinavia) and raises no problems of special interest.
A voyage to Kerguelen in the sealer Edward in 1897–98
Authors: Evans Hugh B.
Published: October 2009

Charles Rowlands, a tea planter and a cousin of mine, decided to finance a sealing expedition from Australia to Kerguelen [Iles Kerguelen], and since he could not go himself he gave me the opportunity of looking after his interests. I went out in the P&O steamer China, all expenses paid. I left England in the middle of 1897 and arrived in Australia in the early spring. I was paid £100, with all expenses. I shared the officers' cabin and was not to be allowed to do crew duties. I was 22 years old at the time.
A prehistoric population change in the Bering Strait region
Authors: Bockstoce John
Published: October 2009

The Birnirk culture is important in Inupiak Eskimo prehistory because the Thule and Western Thule cultures and all recent prehistoric Eskimo cultures derive from it. Its appearance on the American side of Bering Strait has puzzled archaeologists because it is linked to the cultures of the Asian side of the strait and is not lineally related to the cultures, Norton and Ipiutak, that it replaced in Alaska. Recent excavations at Cape Nome, Alaska, have shed light on the nature of this replacement. I carried out these excavations during 1969–71 under the auspices of the University Museum of the University of Pennsylvania and under the supervision of Professor Froelich Rainey. The University Museum and the Explorers Club gave financial assistance.
Social and economic problems of Finnish Lapland
Authors: Ingold T.
Published: October 2009

In this paper I review some of the fields in which Lapps are involved in the over-all development, or lack of development, of northern Finland. I shall limit my perspective in two ways: first, I am concerned to document those issues that directly affect the Lapps at present. This present is taken as 1972, since I was in north-east Lapland in 1971–72, carrying out fieldwork among the Skolt Lapps; my view is thus somewhat biassed to the east (Ingold, 1971). Secondly, I am not directly concerned with the position of Lapps in Norway, Sweden, and the Soviet Union. This is not to deny that there exists a great deal in common among Lapps of these different countries. Equally, the fortunes of Lapps have been crucially affected by the different circumstances pertaining in the nation-states which, through history, have been drawn up around them. My subject, then, concerns how Lapps fare, economically, culturally and politically, in the context of modern Finland.
Polar Bear tagging in Alaska, 1968
Authors: Lentfer J. W.
Published: October 2009

The Alaska Department of Fish and Game started marking Polar Bears (Ursus maritimus) in 1967 to obtain life history information (Lentfer, 1968), and continued in 1968 with the assistance of the US Bureau of Sport Fisheries and Wildlife. Special thanks for use of facilities are given to the Arctic Research Laboratory at Barrow and to the Tin City and Cape Lisburne Air Force stations. Participating biologists were J. W. Lentfer, L. H. Miller, S. H. Eide, and G. N. Bos of the Alaska Department of Fish and Game and J. W. Brooks of the US Bureau of Sport Fisheries and Wildlife.
Aspects of the frequency of calms in Antarctica
Authors: Streten N. A.
Published: October 2009

Much of the literature relating to the climate of Antarctica has been concerned with the prevalence of strong winds and accompanying drifting snow which are such a feature of the environment. Not so well known are the variations, both with time and geographical location, in the frequency of occurrence of calms and light winds, or the synoptic scale and local influences associated with these conditions. However, calms are frequently of considerable operational importance to expeditions and the meteorological factors associated with them have some significance as indicators of general circulation characteristics.
Canada's northern policy: retrospect and prospect
Authors: Judd David
Published: October 2009

That sentence referred, in fact, to the impending transfer of the Arctic islands to Canada in 1879, but it could have applied, just as aptly, to the whole of northern Canada. The first part of it was largely correct; the second part is still a matter for conjecture, debate and experiment.

Most of the Canadian Government's sporadic forays into the north from 1880 onwards were motivated by the reaction of politicians and officials aliens in the Arctic. There was nothing else in the north for a government to be concerned about. The fur trade was important to the Hudson's Bay Company, and it was to become important to many of the Eskimos, but had lost its pre-eminence in a nation where trans-continental railways and millions of immigrants were the priorities of the day. The great age of Arctic exploration was ending: a North West Passage was irrelevant in a world that was planning a Panama Canal. The whalers too would depart from northern waters, and the missionaries and the Hudson Bay factors would left to themselves.
The use of light aircraft in support of field activities in high Arctic latitudes
Authors: Moore Terris
Published: October 2009

During the summer of 1956 W. W. Phipps flew a Piper Super-Cub aircraft solo from Pelley Lake to Eureka, and there carried out a series of local flights in Ellesmere Island on behalf of the National Film Board of Canada. The aircraft was equipped with standard tandem wheel undercarriage. Carrying one passenger, Phipps landed at Fort Conger, Alert and Cape Columbia. The round trip from Pelley Lake took 11 days covering a distance of 4500 miles in fifty flying hours.

On 25 July 1958 the writer left Ottawa with a float-equipped Piper Super-Cub to fly to Eureka. Overnight stops were made at Moose Factory, Severn, Churchill (two nights on account of low cloud), an unnamed lake 50 miles short of Baker Lake, Baker Lake itself (because of strong N.W. winds), an unnamed pond 10 miles south-west of Bellot Strait, and at Resolute.
Water supply and sewage disposal in permafrost areas of northern Canada
Authors: Dickens H. B.
Published: October 2009

Although the principles of water supply and sewage disposal in the north of Canada are the same as those for more temperate regions, the physical features of the installations often vary with the influence of low temperature and permafrost. These not only create technical problems of design but, when coupled with the relative isolation of most northern sites, they also introduce serious economic considerations. Operating costs as well as initial construction costs are higher, making facilities of the kind normally provided too expensive for many people.
Australian Antarctic Ice Thickness Measurements and Sastrugi Observations, Mac-Robertson Land, 1957–58
Authors: Mather K. B. , Goodspeed M. J.
Published: October 2009

The principal field activity of the A.N.A.R.E. party at Mawson during the 1957–58 summer was the determination of ice thickness along a section of the Antarctic plateau. In previous years the summer expeditions inland had concentrated on the survey and geology of the Prince Charles Mountains, south-east of Mawson. While this programme was continued in 1957–58 as opportunity presented, and in fact air photography of the ranges almost completed, the main I.G.Y. field effort was directed towards seismic ice-depth determinations. These were the responsibility of the Bureau of Mineral Resources, and a seismologist was seconded to the Antarctic Division, together with equipment for the purpose.

The traverse made lay southwards from Mawson, following approximately the meridian 62° 08′ E. It was known from prior air reconnaissance that a south-westerly spur of the Prince Charles Mountains system cut across the route in the vicinity of lat. 73° to 74° S., but the exact location was unknown. The intention was to map this spur, then skirt it to the west and resume the seismic traverse southwards.
An Arctic Whaling Journal of 1791
Authors: Savours Ann
Published: October 2009

In 1956 the University Library of Aberdeen acquired a journal written by one George Kerr, surgeon aboard the Aberdeen whaling ship Christian, during a voyage to the whale fisheries in the Greenland Sea, west and north-west of Spitsbergen. The voyage, which was in 1791, took them as far north as lat. 81° N. The journal is seventy-nine pages long, on quarto-sized paper, and written in brown ink in a good, clear hand. A number of whalers' log books exist, recording winds and tides and noting extraordinary events, there are also published memoirs covering several voyages or giving a picture of whaling in general—like William Scoresby's book which includes an exciting narrative of the voyage of the Esk, under his command, to Spitsbergen waters, and of her preservation under most difficult circumstances. Kerr's journal is a spirited day-to-day account of an eventful though profitless voyage—the ship returning “clean” with no catch.
Palaeomagnetic investigation of Arctic rocks at Cambridge
Authors: Harland W. B.
Published: October 2009

Recent advances in rock magnetism have established the value of measuring the direction of the remanent magnetism of many kinds of rock. Provided certain conditions are satisfied, individual measurements relate to magnetic pole positions and sufficient measurements give a mean position which may indicate the geographical pole. Thus from determinations of a number of samples of rock from a geological formation, with suitable corrections, the latitude and geographical orientation of the rock at the time when it assumed its magnetic field may be postulated. This restricts and, in due course, may define palaeogeographical reconstructions and so serve to identify movements of the crust in relation to each other and to the poles. Results so far obtained show that averaged pole positions from successive rocks, ranging through many hundreds of millions of years in the same relatively undisturbed areas, lie on curves extending through many tens of degrees of arc. Moreover, similar curves, uniting near the present poles today but diverging considerably when traced backwards in time, derive from different continents, suggesting that both relative continental movements and polar wandering must be taken seriously. From the pattern of pole positions from dated rocks it may be possible to correlate rocks of unknown age (e.g. unfossiliferous and Pre-Cambrian rocks), and solve some petrogenetic problems.
Orographic clouds in north Victoria Land from AVHRR images
Authors: Zibordi Giuseppe , Frezzotti Massimo
Published: October 2009

Orographic clouds over north Victoria Land, East Antarctica, have been observed in Advanced Very High Resolution Radiometer (AVHRR) satellite imagery. These occasional clouds are discussed through analysis of their spectral features in AVHRR data. Temporal occurrence, spatial extension, and direction of the clouds are also discussed in relation to meteorological data for two periods characterised by katabatic winds, in December 1992 and January 1993.
Identifying national interests in Antarctica: the case of Canada
Authors: Beck Peter J.
Published: October 2009

During the past decade, most publications on Antarctic politics and law have concentrated upon broader developments at the Antarctic Treaty System (ATS) level. Less attention has been devoted to the nature of national interests in Antarctica and ways of balancing different policy objectives through time. Canada, though failing to accede to the Antarctic Treaty until 1988, offers a useful case study illuminating the broad range of interests influencing the policy of individual governments toward Antarctica, and particularly the reasons why states lacking clear national interests therein participate in the ATS. For Canada, Antarctica has always been viewed principally from an Arctic perspective. The resulting low priority of Antarctica explains Canada's initial non-involvement in the ATS. However, by the late 1980s, accession to the Antarctic Treaty was deemed desirable on policy grounds, even if Canada assumed only alow key role in the ATS, at least until 1994–1995, when the appointment of an Ambassador for Circumpolar Affairs was apparently followed by a more active bi-polar strategy.
Pingo growth ages in the delta area, Adventdalen, Spitsbergen
Authors: Yoshikawa Kenji , Nakamura Toshio
Published: October 2009

The open-system pingos of Spitsbergen are formed outside terminal moraines, fault zones, and delta areas. Pingos in this study area were located near the shore in active geologic uplift areas. Three open-system pingos in the Adventdalen delta area of Spitsbergen were examined. Pingos closer to shore are younger in age and those farther away are older. Growth of these pingos occurs rapidly after initial submarine uplift and a minimum thickness of permafrost is established. Hut pingo, which is farthest from the sea, was formed after 6980±70 a BP (NUTA-3856). Driftwood associated with Longyear pingo, in the middle part of the delta, was dated at 2800±90 a BP. The radiocarbon age of peat near the shore pingo, Lagoon pingo, was 140±20 a BP. The growth of the pingos is related to transgression and development of permafrost.
Linguistic science and nationalist revolution: Expert knowledge and the making of sameness in pre-independence Ireland
Authors: FRENCH BRIGITTINE M.
Published: October 2009

This article examines the linguistic ideological work entailed in the analyses of Irish by the “revolutionary scholar” and cofounder of the Gaelic League, Eoin MacNeill. It does so to discern one central way in which the essentialized link between the Irish language and a unified Irish people became an efficacious political construction during the armed struggle for independence in the early 20th century. It shows how MacNeill used authoritative linguistic science to engender nationalist sentiment around Irish through semiotic processes even as he challenged a dominant conception of language prevalent in European nationalist movements and social thought. The essay argues that MacNeill wrote against the unilateral valorization of codified linguistic homogeneity and embraced the heterogeneous variation of spoken discourse even as he sought to consolidate Irish national identity through sameness claims. This critical examination suggests that scholars of nationalism reconsider the taken-for-granted homogenizing efforts of nationalist endeavors that are ubiquitously presumed to negatively sanction linguistic variation. (Nationalism, linguistic ideology, Ireland, semiotics, heterogeneity, Eoin MacNeill, Gaelic League, Europe, scientific knowledge)
Mantle flow in subduction systems: The subslab flow field and implications for mantle dynamics
Authors: Long Maureen D. , Silver Paul G.
Published: October 2009

The character of the mantle flow field in subduction zones remains poorly understood, despite its importance for our understanding of subduction dynamics. In particular, little attention has been paid to mantle flow beneath subducting slabs. In order to identify processes that make first‐order contributions to the global pattern of subslab mantle flow, we have compiled shear wave splitting measurements from subduction zones worldwide from previously published studies and estimated average splitting parameters for the subslab region. Globally, the subslab region is overwhelmingly dominated by trench‐parallel fast splitting directions. We tested for relationships between splitting delay time, a measure of the strength of anisotropy, and parameters that are indicators of tectonic processes, such as trench migration velocity, convergence velocity and obliquity, age of subducting lithosphere, and slab dip, curvature, seismicity, and thickness. We used several different plate motion models to describe plate and trench motions and evaluated the differences among the models. We find that only one parameter, namely, the trench migration velocity in a Pacific hot spot reference frame, appears to correlate well with the strength of the subslab splitting signal. This finding supports a model in which the mantle beneath subducting slabs is dominated by three‐dimensional flow induced by trench migration. We explore several implications of our model for various aspects of mantle dynamics, including the choice of a suitable reference frame(s) for mantle flow, the existence of a thin decoupling zone between slabs and the subslab mantle, and consequences for mass transfer between the upper and lower mantle.
A divergence‐free spatial interpolator for large sparse velocity data sets
Authors: Vennell Ross , Beatson Rick
Published: October 2009

A 2‐D divergence‐free interpolator is presented which is demonstrated to give more realistic values between sparse velocity data than interpolating velocity components independently. The interpolator enforces physical dependence between the velocity components by ensuring mass is conserved. Tests using data for a synthetic eddy show that independent interpolation of components can give unrealistic velocities between widely spaced data. However, divergence‐free interpolation can reproduce the eddy almost as well with sparse data as with dense data. In the synthetic tests the divergence‐free radial basis function (RBF) interpolator performed as well as, or better than, optimal interpolation. A significant advantage of the “greedy fit” RBF interpolator implemented here is the small number of coefficients required to describe the interpolating surface. For large data sets this gives the interpolator a significant computational advantage over techniques, like Optimal Interpolation, which require one coefficient per data point. The RBF's economy of parameters and imposing physics with the divergence‐free constraint makes RBF interpolation of sparse data much more resistant to following the noise. The 2‐D divergence‐free interpolator can be used to interpolate geostrophic velocities or the horizontal transport of high‐frequency flows such as tidal currents. Tests with data from the local dynamics experiment moorings and from moving vessel acoustic Doppler current profiler measurements of tidal flow show the divergence‐free interpolator is better able to reproduce data left out of the interpolation than interpolating velocity components independently.
Spatiotemporal sequence of Himalayan debris flow from analysis of high‐frequency seismic noise
Authors: Burtin A. , Bollinger L. , Cattin R. , Vergne J. , Nábělek J. L.
Published: October 2009

During the 2003 summer monsoon, the Hi‐CLIMB seismological stations deployed across the Himalayan Range detected bursts of high‐frequency seismic noise that lasted several hours to days. On the basis of the cross correlation of seismic envelopes recorded at 11 stations, we show that the largest transient event on 15 August was located nearby a village partially destroyed on that day by a devastating debris flow. This consistency in both space and time suggests that high‐frequency seismic noise analysis can be used to monitor debris flow generation as well as the evacuation of the sediment. A systematic study of one year of seismic noise, focusing on the detection of similar events, provides information on the spatial and temporal occurrence of mass movements at the front of the Himalayas. With a 50% probability of occurrence of a daily event, a total of 46 debris flows are seismically detected. Most of them were generated in regions of steep slopes, large gullies, and loose soils during the 2003 summer monsoon storms. These events are compared to local meteorological data to determine rainfall thresholds for slope failures, including the cumulative rainfall needed to bring the soil moisture content to failure capacity. The inferred thresholds are consistent with previous estimates deduced from soil studies as well as sediment supply investigations in the area. These results point out the potential of using seismic noise as a dedicated tool for monitoring the spatiotemporal occurrence of landslides and debris flows on a regional scale.
Reactivation of tectonics, crustal underplating, and uplift after 60 Myr of passive subsidence, Raukumara Basin, Hikurangi‐Kermadec fore arc, New Zealand: Implications for global growth and recycling of continents
Authors: Sutherland Rupert , Stagpoole Vaughan , Uruski Christopher , Kennedy Callum , Bassett Daniel , Henrys Stuart , Scherwath Martin , Kopp Heidrun , Field Brad , Toulmin Suzannah , Barker Daniel , Bannister Stephen , Davey Fred , Stern Timothy , Flueh Ernst R.
Published: October 2009

We use seismic reflection and refraction data to determine crustal structure, to map a fore‐arc basin containing 12 km of sediment, and to image the subduction thrust at 35 km depth. Seismic reflection megasequences within the basin are correlated with onshore geology: megasequence X, Late Cretaceous and Paleogene marine passive margin sediments; megasequence Y, a ∼10,000 km3 submarine landslide emplaced during subduction initiation at 22 Ma; and megasequence Z, a Neogene subduction margin megasequence. The Moho lies at 17 km beneath the basin center and at 35 km at the southern margin. Beneath the western basin margin, we interpret reflective units as deformed Gondwana fore‐arc sediment that was thrust in Cretaceous time over oceanic crust 7 km thick. Raukumara Basin has normal faults at its western margin and is uplifted along its eastern and southern margins. Raukumara Basin represents a rigid fore‐arc block >150 km long, which contrasts with widespread faulting and large Neogene vertical axis rotations farther south. Taper of the western edge of allochthonous unit Y and westward thickening and downlap of immediately overlying strata suggest westward or northwestward paleoslope and emplacement direction rather than southwestward, as proposed for the correlative onshore allochthon. Spatial correlation between rock uplift of the eastern and southern basin margins with the intersection between Moho and subduction thrust leads us to suggest that crustal underplating is modulated by fore‐arc crustal thickness. The trench slope has many small extensional faults and lacks coherent internal reflections, suggesting collapse of indurated rock, rather than accretion of >1 km of sediment from the downgoing plate. The lack of volcanic intrusion east of the active arc, and stratigraphic evidence for the broadening of East Cape Ridge with time, suggests net fore‐arc accretion since 22 Ma. We propose a cyclical fore‐arc kinematic: rock moves down a subduction channel to near the base of the crust, where underplating drives rock uplift, oversteepens the trench slope, and causes collapse toward the trench and subduction channel. Cyclical rock particle paths led to persistent trench slope subsidence during net accretion. Existing global estimates of fore‐arc loss are systematically too high because they assume vertical particle paths.
Assessing the impact of climate change on water resources in Iran
Authors: Abbaspour Karim C. , Faramarzi Monireh , Ghasemi Samaneh Seyed , Yang Hong
Published: October 2009

As water resources become further stressed due to increasing levels of societal demand, understanding the effect of climate change on various components of the water cycle is of strategic importance in management of this essential resource. In this study, we used a hydrologic model of Iran to study the impact of future climate on the country's water resources. The hydrologic model was created using the Soil and Water Assessment Tool (SWAT) model and calibrated for the period from 1980 to 2002 using daily river discharges and annual wheat yield data at a subbasin level. Future climate scenarios for periods of 2010–2040 and 2070–2100 were generated from the Canadian Global Coupled Model (CGCM 3.1) for scenarios A1B, B1, and A2, which were downscaled for 37 climate stations across the country. The hydrologic model was then applied to these periods to analyze the effect of future climate on precipitation, blue water, green water, and yield of wheat across the country. For future scenarios we found that in general, wet regions of the country will receive more rainfall while dry regions will receive less. Analysis of daily rainfall intensities indicated more frequent and larger‐intensity floods in the wet regions and more prolonged droughts in the dry regions. When aggregated to provincial levels, the differences in the predictions due to the three future scenarios were smaller than the uncertainty in the hydrologic model. However, at the subbasin level the three climate scenarios produced quite different results in the dry regions of the country, although the results in the wet regions were more or less similar.
Mass spectral characterization of submicron biogenic organic particles in the Amazon Basin
Authors: Chen Q. , Farmer D. K. , Schneider J. , Zorn S. R. , Heald C. L. , Karl T. G. , Guenther A. , Allan J. D. , Robinson N. , Coe H. , Kimmel J. R. , Pauliquevis T. , Borrmann S. , Pöschl U. , Andreae M. O. , Artaxo P. , Jimenez J. L. , Martin S. T.
Published: October 2009

Submicron atmospheric particles in the Amazon Basin were characterized by a high‐resolution aerosol mass spectrometer during the wet season of 2008. Patterns in the mass spectra closely resembled those of secondary‐organic‐aerosol (SOA) particles formed in environmental chambers from biogenic precursor gases. In contrast, mass spectral indicators of primary biological aerosol particles (PBAPs) were insignificant, suggesting that PBAPs contributed negligibly to the submicron fraction of particles during the period of study. For 40% of the measurement periods, the mass spectra indicate that in‐Basin biogenic SOA production was the dominant source of the submicron mass fraction, contrasted to other periods (30%) during which out‐of‐Basin organic‐carbon sources were significant on top of the baseline in‐Basin processes. The in‐Basin periods had an average organic‐particle loading of 0.6 μg m−3 and an average elemental oxygen‐to‐carbon (O:C) ratio of 0.42, compared to 0.9 μg m−3 and 0.49, respectively, during periods of out‐of‐Basin influence. On the basis of the data, we conclude that most of the organic material composing submicron particles over the Basin derived from biogenic SOA production, a finding that is consistent with microscopy observations made in a concurrent study. This source was augmented during some periods by aged organic material delivered by long‐range transport.
Evolution of the quasi 2‐day wave during January 2006
Authors: McCormack J. P. , Coy L. , Hoppel K. W.
Published: October 2009

We examine the evolution of the quasi 2‐day wave in the middle atmosphere during the period from 5 January to 5 February 2006 using global synoptic meteorological fields from the high‐altitude Navy Operational Global Atmospheric Prediction System Advanced Level Physics, High Altitude (NOGAPS‐ALPHA) forecast‐assimilation system. This period is characterized by a high level of planetary wave activity in the Northern Hemisphere (winter) extratropical stratosphere prior to a sudden stratospheric warming (SSW) on 20 January 2006. Space‐time spectral analysis of 6‐hourly NOGAPS‐ALPHA fields finds the largest quasi 2‐day wave amplitudes in the Southern Hemisphere (summer) extratropical upper mesosphere. Eliassen‐Palm flux diagnostics indicate that this extratropical quasi 2‐day wave is related to baroclinic instability along the equatorward flank of the summer easterly jet. The quasi 2‐day wave is also evident in NOGAPS‐ALPHA water vapor fields near the tropical stratopause and is related to barotropic instability. We find that the strong planetary wave activity leading up to the SSW produced an enhanced northward component of the residual meridional circulation that influenced the background zonal winds and, by extension, the quasi 2‐day wave forcing in both the tropical and extratropical regions. In the tropical region, the combination of enhanced horizontal momentum advection by the residual meridional circulation and inertially unstable circulations related to planetary wave breaking in the subtropics produced conditions favoring barotropic instability. In the extratropical region, the enhanced residual meridional circulation altered the zonal wind tendency through increased Coriolis torque.
Improving ice core interpretation using in situ and reanalysis data
Authors: Thomas E. R. , Bracegirdle T. J.
Published: October 2009

Back trajectory analysis, provided by the British Atmospheric Data Centre using meteorological parameters from the European Centre for Medium‐Range Weather Forecasts (ECMWF) reanalysis ERA‐40 (1980–2001) and operational analysis (2002–2006), is used to investigate transport pathways and source regions of climate proxies preserved in a new ice core (Gomez) from the southwestern Antarctic Peninsula. The ECMWF data are compared with automatic weather station data and ice core annual accumulation records to demonstrate that the ECMWF data capture a large proportion of the annual and subseasonal precipitation variability at the site. The back trajectories reveal that precipitation preserved in the ice core accumulation record, and hence climate proxies contained therein, originate from the low‐pressure systems from the Bellingshausen Sea transported via circumpolar westerly winds. Hence, precipitation‐dependent ice core proxies, such as isotopic composition, will be influenced by both localized sea ice extent and large‐scale circulation changes, such as the Southern Annular Mode. Sea ice proxies from the ice core are expected to be dominated by sea ice extent in the Bellingshausen Sea but also influenced by sea ice in the Weddell Sea, with a small proportion of air mass trajectories originating from this region during the summer. Comparison with other ice core sites reveals a stronger influence of easterly transport at more northerly locations, thus explaining the observed differences in snow accumulation records between ice cores and the poor correlation with instrumental records at these sites.
Optimizing a direct string magnetic gradiometer for geophysical exploration
Authors: Sunderland Andrew , Ju Li , Blair David G. , McRae Wayne , Veryaskin Alexey V.
Published: October 2009

Magnetic gradiometers are tools for geophysical exploration. The magnetic gradient is normally calculated by subtracting the outputs of two total field magnetometers which are separated by a baseline. Here we present a unique device that directly measures magnetic gradients using only a single string as its sensing element. The main advantage of a direct string magnetic gradiometer is that only gradients can induce second harmonic string vibrations. A high common mode rejection ratio is thus naturally achieved without any balancing technique. Performance depends on the ability to dissipate heat while minimizing air damping. By combining high current, an elevated temperature and low pressure, we can easily achieve sensitivity of 0.18 nT/m/Hz. Further increases in sensitivity can be attained by optimizing the sensing element. In this paper we present an in-depth study of the most critical parameters of the magnetic gradiometer. We describe the design for the next generation of sensor, which will reach the required sensitivity of 0.01 nT/m/Hz using only 1 W of power. By combining a few single-axis magnetic gradiometer modules, it will be possible to deploy a full tensor magnetic gradiometer with more than sufficient sensitivity for airborne geophysical applications.
Fixed points, stable manifolds, weather regimes, and their predictability
Authors: Deremble Bruno , D’Andrea Fabio , Ghil Michael
Published: October 2009

In a simple, one-layer atmospheric model, we study the links between low-frequency variability and the model’s fixed points in phase space. The model dynamics is characterized by the coexistence of multiple “weather regimes.” To investigate the transitions from one regime to another, we focus on the identification of stable manifolds associated with fixed points. We show that these manifolds act as separatrices between regimes. We track each manifold by making use of two local predictability measures arising from the meteorological applications of nonlinear dynamics, namely, “bred vectors” and singular vectors. These results are then verified in the framework of ensemble forecasts issued from “clouds” (ensembles) of initial states. The divergence of the trajectories allows us to establish the connections between zones of low predictability, the geometry of the stable manifolds, and transitions between regimes.
Mechanism of the swift heavy ion induced epitaxial recrystallization in predamaged silicon carbide
Authors: Benyagoub A. , Audren A.
Published: October 2009

Although silicon carbide has attracted extensive investigations of ion irradiation effects at low energy owing to its potential use in harsh environments, very few works were carried out in the field of ion irradiation at high energy. A recent preliminary study exploring the combination of low and high energy ion irradiation effects in silicon carbide revealed that the damaged layer formed by low energy ion irradiation can undergo an epitaxial recrystallization under subsequent swift heavy ion irradiation. The present paper is devoted to the investigation of the mechanisms at the origin of this phenomenon by performing additional experiments. A detailed analysis of the kinetics of this recrystallization effect demonstrates that the latter cannot be explained by the models proposed for the well-known ion-beam-induced epitaxial crystallization process. Furthermore, it is found that this effect can be accounted for by a mechanism combining the melting within the ion tracks of the amorphous zones through a thermal spike process and their subsequent epitaxial recrystallization initiated from the neighboring crystalline regions wherever the size of the latter surpasses a certain critical value.
Thermal conductivity studies of metal dispersed multiwalled carbon nanotubes in water and ethylene glycol based nanofluids
Authors: Jha Neetu , Ramaprabhu S.
Published: October 2009

High thermal conducting metal nanoparticles have been dispersed on the multiwalled carbon nanotubes (MWNTs) outer surface. Structural and morphological characterizations of metal dispersed MWNTs have been carried out using x-ray diffraction analysis, high resolution transmission electron microscopy, energy dispersive x-ray analysis, and Fourier transform infrared spectroscopy. Nanofluids have been synthesized using metal-MWNTs in de-ionized water (DI water) and ethylene glycol (EG) base fluids. It has been observed that nanofluids maintain the same sequence of thermal conductivity as that of metal nanoparticles Ag-MWNTs>Au-MWNTs>Pd-MWNTs. A maximum enhancement of 37.3% and 11.3% in thermal conductivity has been obtained in Ag-MWNTs nanofluid with DI water and EG as base fluids, respectively, at a volume fraction of 0.03%. Temperature dependence study also shows enhancement of thermal conductivity with temperature.
Multiscale modeling of the thermal conductivity of polycrystalline silicon carbide
Authors: Crocombette Jean-Paul , Gelebart Lionel
Published: October 2009

A multiscale modeling, involving molecular dynamics and finite element calculations, of the degradation of the thermal conductivity of polycrystalline silicon carbide due to the thermal (Kapitza) resistances of grain boundaries is presented. Molecular dynamics simulations focus on the ⟨111⟩ family of tilt grain boundaries in cubic SiC. For large tilt angles a simple symmetry and shift procedure is used to generate the grain boundaries while for small angles the boundary structure is obtained by inserting arrays of edge dislocations. The energy and thermal resistances of the grain boundaries are presented. The latter are fed into a finite element homogenization procedure, which enables to calculate the effective thermal conductivity of the SiC polycrystal as a function of its average grain size. The decrease in the thermal conductivity of a polycrystal as a function of its grain size is qualitatively reproduced. However, available experimental values of the thermal conductivity of polycrystalline SiC tend to indicate that the present Kapitza resistances cannot be directly used for prediction of the thermal conductivity of polycrystalline silicon carbide. We suggest possible explanations for this discrepancy, which seems rather common to Kapitza resistances calculated with molecular dynamics simulations.
Shock wave driven liquid microjets for drug delivery
Authors: Menezes Viren , Kumar Satyam , Takayama Kazuyoshi
Published: October 2009

A nonintrusive, minimally invasive, needle-less technique to deliver liquids into soft targets is presented. The technique uses a laser-induced shock wave to drive a liquid microjet at a very high speed such that the jet has sufficient momentum to penetrate soft targets. The method can be used to deliver liquid drugs into soft tissues in the human body. The liquid to be delivered is sandwiched between 200 μm thick aluminum foil and a base plate with a perforation of 100 μm diameter. The aluminum foil is ablated using an Nd:YAG laser beam in order to launch a shock wave through it. The shock wave from the foil is transmitted to the sandwiched liquid, which becomes pressurized by the shock propagation and emanates as a microjet through the perforation in the base plate. The microjet thus generated has a steady, average speed of over 200 m/s. The technique has been tested on gelatin models (5% gelatin), in which the jet penetrated to a depth of more than a millimeter.
A model for structural defects in nanomagnets
Authors: Apolonio F. A. , Moura-Melo W. A. , Crisafuli F. P. , Pereira A. R. , Silva R. L.
Published: October 2009

A model for describing structural pointlike defects in nanoscaled ferromagnetic materials is presented. Its details are explicitly developed whenever it interacts with a vortexlike state comprised in a thin nanodisk. Among others, our model yields results for the vortex equilibrium position under the influence of several defects along with an external magnetic field that is shown to be in good qualitative agreement with experiments. We also discuss how such defects may affect the vortex motion, such as its gyrotropic oscillation and dynamical polarization reversal.
Quantum mechanical simulation of nanosized metal-oxide-semiconductor field-effect transistor using empirical pseudopotentials: A comparison for charge density occupation methods
Authors: Jiang Xiang-Wei , Deng Hui-Xiong , Li Shu-Shen , Luo Jun-Wei , Wang Lin-Wang
Published: October 2009

The atomistic pseudopotential quantum mechanical calculations are used to study the transport in million atom nanosized metal-oxide-semiconductor field-effect transistors. In the charge self-consistent calculation, the quantum mechanical eigenstates of closed systems instead of scattering states of open systems are calculated. The question of how to use these eigenstates to simulate a nonequilibrium system, and how to calculate the electric currents, is addressed. Two methods to occupy the electron eigenstates to yield the charge density in a nonequilibrium condition are tested and compared. One is a partition method and another is a quasi-Fermi level method. Two methods are also used to evaluate the current: one uses the ballistic and tunneling current approximation, another uses the drift-diffusion method.
Quartz crystal microbalance-based system for high-sensitivity differential sputter yield measurements
Authors: Rubin B. , Topper J. L. , Farnell C. C. , Yalin A. P.
Published: October 2009

We present a quartz crystal microbalance-based system for high sensitivity differential sputter yield measurements of different target materials due to ion bombardment. The differential sputter yields can be integrated to find total yields. Possible ion beam conditions include ion energies in the range of 30–350 eV and incidence angles of 0°–70° from normal. A four-grid ion optics system is used to achieve a collimated ion beam at low energy (<100 eV) and a two-grid ion optics is used for higher energies (up to 750 eV). A complementary weight loss approach is also used to measure total sputter yields. Validation experiments are presented that confirm high sensitivity and accuracy of sputter yield measurements.
A direct optical method for the study of grain boundary melting
Authors: Thomson E. S. , Wettlaufer J. S. , Wilen L. A.
Published: October 2009

The structure and evolution of grain boundaries underlies the nature of polycrystalline materials. Here we describe an experimental apparatus and light reflection technique for measuring disorder at grain boundaries in optically clear material, in thermodynamic equilibrium. The approach is demonstrated on ice bicrystals. Crystallographic orientation is measured for each ice sample. The type and concentration of impurity in the liquid can be controlled and the temperature can be continuously recorded and controlled over a range near the melting point. The general methodology is appropriate for a wide variety of materials.
Error and efficiency of replica exchange molecular dynamics simulations
Authors: Rosta Edina , Hummer Gerhard
Published: October 2009

We derive simple analytical expressions for the error and computational efficiency of replica exchange molecular dynamics (REMD) simulations (and by analogy replica exchange Monte Carlo simulations). The theory applies to the important case of systems whose dynamics at long times is dominated by the slow interconversion between two metastable states. As a specific example, we consider the folding and unfolding of a protein. The efficiency is defined as the rate with which the error in an estimated equilibrium property, as measured by the variance of the estimator over repeated simulations, decreases with simulation time. For two-state systems, this rate is in general independent of the particular property. Our main result is that, with comparable computational resources used, the relative efficiency of REMD and molecular dynamics (MD) simulations is given by the ratio of the number of transitions between the two states averaged over all replicas at the different temperatures, and the number of transitions at the single temperature of the MD run. This formula applies if replica exchange is frequent, as compared to the transition times. High efficiency of REMD is thus achieved by including replica temperatures in which the frequency of transitions is higher than that at the temperature of interest. In tests of the expressions for the error in the estimator, computational efficiency, and the rate of equilibration we find quantitative agreement with the results both from kinetic models of REMD and from actual all-atom simulations of the folding of a peptide in water.
Parameters of a collisional radio-frequency sheath and dust characteristics resulting from the microparticle levitation
Authors: Yaroshenko V. V. , Antonova T. , Thomas H. M. , Morfill G. E.
Published: October 2009

The screening length, the time-average electric field, and the particle charge as well as the local vertical gradients of these quantities are determined experimentally within a sheath of a capacitively coupled rf, 13.56 MHz, discharge at enhanced argon gas pressures of 30, 55, and 100 Pa. The parameters are derived directly from comparative measurements of levitation positions of the particles of different sizes and variations in the levitation heights caused by formation of new dust layers. The electrostatic effect of the horizontally extended dust layers on the sheath electric field is investigated.
Coherent emission from large arrays of discrete Josephson junctions
Authors: Song F. , Müller F. , Behr R. , Klushin A. M.
Published: October 2009

We observed coherent emission at the frequency of 76 GHz from a large-area array of 7500 niobium junctions embedded in the quasioptical resonator at liquid helium temperature. The maximal detected power of 2 μW was measured by a room temperature superheterodyne receiver. To explain the coherent behavior of the array of Josephson junctions, electromagnetic field simulations were performed. Considering the substrate as a dielectric resonator antenna, the coherent emission was excited if the locations of each subarray coincided with the positions of the maximum electric field intensity in the substrate resonance mode.