bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐lived yeast as a model for ageing research
Authors: Piper Peter W.
Published: February 2006

Yeast has essentially two lifespans: a replicative lifespan (the number of daughters produced by each dividing mother cell) and a chronological lifespan (the capacity of stationary (G0) cultures to maintain viability over time). There is a tendency now to label every investigation that addresses these lifespans as ageing research. It is, though, analyses of the longest lifespans that will be most informative about the determinants of longevity and yield results most relevant to ageing in more complex systems. This review addresses these issues and describes the ongoing studies that are now attempting to address ageing in yeast cells of maximal replicative or chronological longevity. Copyright © 2006 John Wiley & Sons, Ltd.
Natural frequencies of laminated piezoelectric plates with internal electrodes
Authors: Lim C.W. , Cheng Z.‐Q. , Reddy J.N.
Published: February 2006

Natural vibrations of laminated piezoelectric plates with internal electrodes are analyzed using the transfer matrix method and the asymptotic expansion method. The steady‐state equations of three‐dimensional linear piezoelectricity reduce to a hierarchy of two‐dimensional equations of the same homogeneous operator. The leading‐order equations are easily solvable, whereas the higher‐order equations may contain secular terms and are not straightforward to find their solutions. The solvability condition is established to calculate higher‐order frequency parameters. The present theoretical formulation is used to provide new results by calculating fundamental frequencies of a rectangular laminated plate with two surface‐affixed piezoelectric actuators, a parallel bimorph, a four‐layered multimorph and a functionally graded plate attached with an actuator.
Some remarks on the asymptotic invertibility of the linearized operator of nonlinear elasticity in the context of the displacement approach
Authors: Monneau R.
Published: February 2006

In this article we study the invertibility of the linearized operator coming from the nonlinear elasticity in the special case of a two‐dimensional thin beam of thickness 2ϵ in one direction and of length 2πL and periodic in the other direction. In the context of the displacement approach, we show that the linearized operator is not invertible for some small compressions of order O(ϵ2/L2) in the direction of the thickness of the beam, and not in the direction of the length as it is usually considered. In particular, we study the kernel of an associated linear operator on an infinite strip. This linear operator depends on a parameter $\overline{\delta}$ which describes the compression with respect to the thickness for $\overline{\delta} <0$. For small enough $\overline{\delta} >0$, we prove that the kernel is trivial; on the contrary for $\overline{\delta} <0$, we rigorously find periodic solutions in the kernel. This last fact is related to the non‐invertibility of the previous linearized operator coming from nonlinear elasticity.
Homelessness in the United States: Assessing Changes in Prevalence and Public Opinion, 1993–2001
Authors: Tompsett Carolyn J. , Toro Paul A. , Guzicki Melissa , Manrique Manuel , Zatakia Jigna
Published: February 2006

A national survey was administered in 1993–1994 (N= 360) and repeated in 2001 (N= 435) to assess the prevalence of homelessness as well as attitudes, opinions and knowledge regarding homelessness. No significant changes in prevalence were found, despite a strong US economy during most of the 7–8 year period. Respondents in 2001 had less stereotyped views of homeless people and were more supportive of services, but came to see homelessness as a less serious problem that was less often due to economic factors. This “mixed” set of findings may reflect both beliefs on the benefits of a good economy and an increased awareness of the complexity of homelessness. Across the surveys, younger, female, liberal, and less wealthy respondents demonstrated more sympathetic attitudes towards homeless people.
The influence of caged mariculture on the early development of sublittoral fouling communities: a pan-European study
Authors: Cook E.J. , Black K.D. , Sayer M.D.J. , Cromey C.J. , Angel D.L. , Spanier E. , Tsemel A. , Katz T. , Eden N. , Karakassis I. , Tsapakis M. , Apostolaki E.T. , Malej A.
Published: February 2006

The development of fouling communities was assessed to investigate the influence of caged mariculture on sublittoral epibiota. Artificial structures were deployed within 10 m of caged mariculture and at a “reference” location between 150 and 500 m of the study site at four coastal locations (Oban, Scotland; Sitia, Crete; Piran, Slovenia; and Eilat, Israel). The fouling community on the artificial structures was measured both quantitatively and qualitatively bi-monthly between June 2001 and December 2001. Multivariate statistical analysis was used to compare community structure between the study sites and locations. Artificial structures deployed at the mariculture site supported a higher epibiotic biomass than at the reference site at Oban and Eilat. Community composition was significantly different between the mariculture and reference site at Eilat. The biological succession on the structures changed from an autotrophic to a heterotrophic mode over the experimental period at all locations with the exception of Oban, where negligible quantities of macroalgae were observed on the structures. Differences in community biomass and succession observed between artificial structures deployed at mariculture and reference sites, particularly in oligotrophic environments, may be caused by enhanced larval settlement and an elevated supply of particulate material and dissolved nutrients to structures adjacent to the fish cages.
Positron emission tomography and magnetic resonance imaging in the diagnosis and prediction of dementia
Authors: Jagust William
Published: February 2006

Background

The diagnosis of dementia, along with the prediction of who will develop dementia, has been assisted by the development of the brain imaging techniques of magnetic resonance imaging (MRI) and positron emission tomography (PET).

Methods

This paper reviews the brain imaging technologies of structural MRI and PET scanning as they have been applied to both the diagnosis of dementia and prediction of who will develop dementia.

Results

Diagnosis has long been enhanced by the use of structural imaging techniques like MRI to rule out non‐degenerative causes of disease. More recently, PET imaging with the glucose metabolic tracer [18F]Fluorodeoxyglucose (FDG) may be useful in providing information on the cause of dementia during life, most specifically in differentiating Alzheimer's disease from frontotemporal lobar degeneration. In addition to diagnosis, potential therapeutic advances have increased interest in prediction of dementia. Both MR and FDG‐PET have shown evidence of change in brain structure and metabolism in several models of individuals at‐risk for dementia, including those with mild cognitive impairment and genetic risk factors.

Conclusions

While these studies have not yet advanced to the level of prospective individual‐subject predictive ability, the pattern of data emerging suggests likely candidate approaches for such studies. The advent of newer techniques such as amyloid imaging with PET and functional MRI may ultimately have relevance for both diagnosis and prediction.
The Northern Ireland life review/life storybook project for people with dementia
Authors: Haight Barbara K. , Gibson Faith , Michel Yvonne
Published: February 2006

There are few interventions that help people with dementia retain or regain a sense of self. Thus, a controlled pilot study examined a life review/life storybook intervention, delivered by familiar care assistants to 30 people with dementia residing in assisted living facilities in Northern Ireland. A multivariate analysis of covariance showed significant change by group (F = 5.01, p < 0.014), particularly on depression (F = 7.54, p < 0.015), communication (F = 23.36, p < 0.005), positive mood (F = 9.47, p < 0.008), and cognition (F = 20.77, p < 0.005), suggesting a potentially promising technique to assist people with dementia.
RETHINKING REPUBLICANISM: VINDICIAE, CONTRA TYRANNOS IN CONTEXT
Authors: MCLAREN ANNE
Published: February 2006

The article takes issue with current orthodoxy concerning early modern republicanism, centred on Quentin Skinner's model of classical republicanism. I argue that historians of political thought need to return to first principles in their practice in order to understand early modern republicanism, and I provide an example by using those principles to reassess one canonical text, Philippe de Plessis Mornay's Vindiciae, contra tyrannos. Reading the Vindiciae in context reveals it as a work whose radicalism lies, not in its engagement with the Roman law tradition, but in its express conviction that each and every individual is responsible for maintaining a covenanted relationship with God. My reassessment tracks the political, and specifically regicidal, consequences of commitment to that belief in England from the late sixteenth through the mid-seventeenth centuries. It destabilizes the anachronistic distinction between ‘political’ and ‘religious’ modes of thought that historians of political thought too often use to characterize early modern political discourse, and it points to the common ground shared and articulated by theorists including, inter alia, John Ponet, George Buchanan, and John Milton. The conclusion considers what this investigation reveals about republicanism as a political phenomenon in Europe and America from the sixteenth through the eighteenth centuries.
THE CONTEXTS AND CONTOURS OF BRITISH ECONOMIC LITERATURE, 1660–1760
Authors: HOPPIT JULIAN
Published: February 2006

This article explores some of the main bibliographical dimensions of economic literature at a time when there was much interest in economic matters but no discipline of economics. By looking at what was published in the round much economic literature is shown to be short, ephemeral, unacknowledged, polemical, and legislatively orientated. This fluidity is underscored by the uncertaintities about what constituted key works of economic literature and by the failure of attempts to make sense of that literature through dictionaries and histories. Economic literature in the period was, consequently, more unstable and uncertain than has often been acknowledged. It cannot, therefore, be simply characterized as either ‘mercantilist’ or nascent ‘political economy’.
FAMINE AND LAND IN IRELAND AND INDIA, 1845–1880: JAMES CAIRD AND THE POLITICAL ECONOMY OF HUNGER
Authors: GRAY PETER
Published: February 2006

The perception of Ireland and India as ‘zones of famine’ led many nineteenth-century observers to draw analogies between these two troublesome parts of the British empire. This article investigates this parallel through the career of James Caird (1816–92), and specifically his interventions in the latter stages of both the Great Irish Famine of 1845–50, and the Indian famines of 1876–9. Caird is best remembered as the joint author of the controversial dissenting minute in the Indian famine commission report of 1880; this article locates the roots of his stance in his previous engagements with Irish policy. Caird's interventions are used to track the trajectory of an evolving ‘Peelite’ position on famine relief, agricultural reconstruction, and land reform between the 1840s and 1880s. Despite some divergences, strong continuities exist between the two interventions – not least concern for the promotion of agricultural entrepreneurship, for actively assisting economic development in ‘backward’ economies, and an acknowledgement of state responsibility for preserving life as an end in itself. Above all in both cases it involved a critique of a laissez-faire dogmatism – whether manifest in the ‘Trevelyanism’ of 1846–50 or the Lytton–Temple system of 1876–9.
EMPIRE DAY IN BRITAIN, 1904–1958
Authors: ENGLISH JIM
Published: February 2006

The celebration of Empire Day in Britain was of greater significance than previous research has suggested. This article disproves the misconception that the festival was restricted in the main to a constituency of schoolchildren. The celebrations had a far wider effect on diverse communities; in many cases the ritual celebration of the British Empire traversed class boundaries and helped to sustain traditional social hierarchies. In the immediate aftermath of the First World War, when unrestrained jingoism became inappropriate, Empire Day retained its hegemonic potency by amalgamating the emerging traditions of sombre commemoration into the repertoire of imperial festivity. Empire Day, although remaining popular during the interwar period, became an arena of passionate contestation. The Conservative party and other groups adopted Empire Day as a vehicle for anti-socialist propaganda, whilst the communist party exploited it as an opportunity to attack British imperialism. Other protests came from local Labour groups and pacifist dissenters. The overt politicization of Empire Day severely disrupted its hegemonic function and the political battles fought over the form and purpose of the celebrations made it difficult to uphold the notion that the festival was merely a benign tribute to a legitimate and natural state of affairs.
MAJOR HUGH POLLARD, MI6, AND THE SPANISH CIVIL WAR
Authors: MACKLIN GRAHAM D.
Published: February 2006

The recently released Special Operations Executive (SOE) personal file of Major Hugh Bertie Campbell Pollard (HS 9/1200/5) sheds new light on the man who helped fly General Franco from the Canary Islands to Morocco, leading ultimately to the overthrow of the democratically elected republican government and thirty-six years of brutal dictatorship. Contrary to the previous portrayal of Pollard, a genial, rough-and-ready gung-ho ‘adventurer’ who flew the future Caudillo to Morocco on a whim, the files reveal Pollard to have been an experienced British intelligence officer, talented linguist, and firearms expert with considerable firsthand experience of wars and revolutions in Mexico, Morocco, and Ireland, where he had served as a police adviser in Dublin Castle during the ‘stormy days’ of the Black and Tans in the early 1920s. Pollard, who listed his hobbies in Who's Who as ‘hunting and shooting’, was the sporting editor of Country Life and a member of Lord Leconfield's hunt. He was also a renowned and passionate firearms expert having written numerous books on the subject including the section on ‘small arms’ for the official war office textbook. His friend Douglas Jerrold, who himself later served in British intelligence, recalled that Pollard ‘looked and behaved, like a German Crown Prince and had a habit of letting off revolvers in any office he happened to visit’. Once Jerrold plucked up the courage to ask Pollard if he had ever killed anybody.
EMPIRE AND INTERNATIONAL RELATIONS IN VICTORIAN POLITICAL THOUGHT
Authors: BELL DUNCAN S. A.
Published: February 2006

This essay surveys recent scholarly work on the political theory of empire and international relations in Britain during the long nineteenth century. It traces the dominant themes and arguments to be found, points to some interpretative and methodological weaknesses, and highlights a number of topics that remain to be explored in detail. I focus on the following: the relationship between liberalism and empire and, in particular, the role played by the idea of civilization in circumscribing liberal claims to universality; the nature and evolution of international law, and the key role that jurisprudential thought played in shaping conceptions of civilization and setting the bounds of legitimacy for imperialism; the vexed relationship between the history of imperial thought and cultural/political history; and the important, though frequently marginalized, role of the colonial empire in the Victorian imperial imagination. Finally, I suggest that areas that remain to be explored in depth include non-liberal visions of international affairs; the role of theology in shaping conceptions of global order; and the balance between the United States, Europe, and the various (and very different) elements of the empire.
PRUSSIA'S ‘TRANS-OCEANIC MOMENT’: THE CREATION OF THE PRUSSIAN ASIATIC TRADE COMPANY IN 1750
Authors: SCHUI FLORIAN
Published: February 2006

In 1750 Frederick II of Prussia created a new trade company in Emden. Diplomats, merchants, and other observers in Britain, France, the Netherlands, and Hamburg reacted with great concern to this Prussian bid to join the world of overseas commerce. These concerns were not unfounded. Frederick pursued his goal with great determination. The article explains why Prussia embarked on this ultimately unsuccessful venture and why established commercial powers such as Britain or the Netherlands felt threatened by the new competitor. In this context the article explores an international debate about political economy that was associated with the creation of the Prussian trade company. This debate took place in Britain, the Netherlands, Hamburg, and Prussia. The case of the Prussian Asiatic trade company suggests that the concepts of Oceanic and Atlantic history need to be extended beyond the narrow stretch of coastal regions. In the Prussian case the drive to join the world of overseas commerce originated from the inland and from a country that had traditionally been oriented towards overland commerce and European expansion. The study of the events and debates associated with the creation of the trade company also suggests a partially new perspective on Prussia's economic policies in the period.
Genetic variation inDrosophila melanogasterpathogen susceptibility
Authors: TINSLEY M. C. , BLANFORD S. , JIGGINS F. M.
Published: February 2006

Genetic variation in susceptibility to pathogens is a central concern both to evolutionary and medical biologists, and for the implementation of biological control programmes. We have investigated the extent of such variation inDrosophila melanogaster, a major model organism for immunological research. We found that within populations, differentDrosophilagenotypes show wide-ranging variation in their ability to survive infection with the entomopathogenic fungusBeauveria bassiana. Furthermore, striking divergence in susceptibility has occurred between genotypes from temperate and tropical African locations. We hypothesize that this may have been driven by adaptation to local differences in pathogen exposure or host ecology. Genetic variation within populations may be maintained by temporal or spatial variation in the costs and benefits of pathogen defence. Insect pathogens are employed widely as biological control agents and entomopathogenic fungi are currently being developed for reducing malaria transmission by mosquitoes. Our data highlight the need for concern about resistance evolution to these novel biopesticides in vector populations.
The Internet and Public–Private Governance in the European Union
Authors: CHRISTOU GEORGE , SIMPSON SEAMUS
Published: February 2006

The EU plays a significant role in public policy aspects of Internet governance, having created in the late 1990s the dot eu Internet Top Level Domain (TLD). This enables users to register names under a European online address label. This paper explores key public policy issues in the emergent governance system for dot eu, because it provides an interesting case of new European transnational private governance. Specifically, dot eu governance is a reconciliation resulting from a governance cultural clash between the European regulatory state and what can be described broadly as the Internet community. The EU has customised the governance of dot eu towards a public–private dispersed agencification model. The paper extends the evidence base on agencification within trans-European regulatory networks and the emergence of private transnational network governance characterised by self-regulation.
The Political Costs of Policy Coherence: Constructing a Rural Policy for Scotland
Authors: JORDAN GRANT , HALPIN DARREN
Published: February 2006

It is not hard to find the complaint that a group of policies are incoherent, operate in silos or are unintegrated. The aspiration to coherence is widespread across all political systems: it is today's idea in good currency. Scholarship has identified conditions that support coherence: a strong constituency with a shared policy image. This article confirms that these are vital sources of more or less coherence, but explores the question of whether more coherence in one area comes at the cost of incoherence elsewhere.

Case study detail contrasts the Scottish Executive's projection of a unified rural policy, with the reality of a persistent Scottish agricultural sector, with contending (multiple) publics with separate and often conflicting agendas: the case study found no unified policy community with shared perceptions. While a lack of coordination may simply be the manifestation of poor policymaking, this piece argues that in other cases the practical limitations on policy harmonization have to be acknowledged. Imperfectly coordinated rural policy may be inevitable as coordination in particular niches is often a casualty of competing priorities. This article argues against over ambitious expectations about the feasibility of integration. Accordingly it suggests that the project to rid policy practice of incoherence is too heroic: instead this article rediscovers the virtues of bargaining among informed and relevant participants, and incremental politics.
Simple two degree of freedom structures and their properties
Authors: Osypiuk Rafael , Finkemeyer Bernd , Skoczowski Stanislaw
Published: February 2006

A two-degree of freedom control system that is most frequently encountered in practice is the so-called Internal Model Control (IMC) structure. However, the design procedure of such a structure does not present an easy task, which implies a limited utility of IMC. In this paper two alternative solutions are proposed that may be lumped together as Model-Following Control (MFC). These are two-loop control systems being easy to implement and offering interesting properties. Theoretical assumptions have been verified experimentally on a two-joint robot manipulator. Both qualitative and quantitative results yielded by experiments are presented and discussed.
High resolution 3D laser scanner measurements of a strike‐slip fault quantify its morphological anisotropy at all scales
Authors: Renard François , Voisin Christophe , Marsan David , Schmittbuhl Jean
Published: February 2006

The surface roughness of a recently exhumed strike‐slip fault plane has been measured by three independent 3D portable laser scanners. Digital elevation models of several fault surface areas, from 1 m2 to 600 m2, have been measured at a resolution ranging from 5 mm to 80 mm. Out of plane height fluctuations are described by non‐Gaussian distribution with exponential long range tails. Statistical scaling analyses show that the striated fault surface exhibits self‐affine scaling invariance with a small but significant directional morphological anisotropy that can be described by two scaling roughness exponents, H1 = 0.7 in the direction of slip and H2 = 0.8 perpendicular to the direction of slip.
Potential transport pathways of terrigenous material in the Gulf of Papua
Authors: Keen Timothy R. , Ko Dong Shan , Slingerland Rudy L. , Riedlinger Shelley , Flynn Peter
Published: February 2006

This work discusses potential transport pathways of terrigenous material in the Gulf of Papua (GoP), New Guinea, using Lagrangian tracers as proxies for clay minerals and finer particles. The tracers are transported by currents from the East Asia Seas implementation of the Navy Coastal Ocean Model. The results suggest that clay minerals input from rivers along the northwest coast of the GoP accumulate on the inner shelf with high concentrations near the mouth of the Fly and Purari Rivers. Finer particles, which are also representative of dissolved metals, are transported eastward along the GoP coast into the Solomon Sea as well as into the Torres Strait to the west. The results also suggest that some finer particles are entrained by eddies within the northern Coral Sea. These results are in qualitative agreement with observations from the region.
New sea spray generation function for spume droplets
Authors: Zhao Dongliang , Toba Yoshiaki , Sugioka Ken‐ichi , Komori Satoru
Published: February 2006

With increasing wind forcing and development of wind waves, more and more sea spray droplets are produced on the sea surface. On the basis of now available observational data from field and laboratories with 10‐m wind speeds ranging from 8 to 41 m/s, it is shown that the traditional approach of using wind speed only fails to describe the increase of spume droplet production, owing to the neglect of effect of wave state. Instead, a nondimensional parameter RB = u*2/ωpν called the windsea Reynolds number (Toba et al., 2006) is very good for characterizing the observational data from laboratories and field, where u* is the friction velocity of air, ωp the angular frequency spectral peak of wind waves, and ν is the kinematic viscosity of air. The windsea Reynolds number RB represents the coupling effect of wind forcing and wind wave state, and can be regarded as a measure of fluid dynamical conditions at the air‐sea boundary layer. A new sea spray generation function for spume droplets is proposed as a function of RB. We conclude that spume droplets begin to be produced as RB exceeds 103. The effects of sea spray droplets on air‐sea transfers are also estimated with the new model. It is found that the heat and momentum fluxes induced by sea spray droplets become comparable to the interfacial fluxes by bulk formulas when RB is greater than 105 and 106, respectively.
New revelations on the nature of organic matter in ice cores
Authors: Grannas Amanda M. , Hockaday William C. , Hatcher Patrick G. , Thompson Lonnie G. , Mosley‐Thompson Ellen
Published: February 2006

Analysis of organic species stored in ice cores provides a unique opportunity to obtain information about the environment of the past. Because of the trace nature of the organic components of interest, studying these species in molecular level detail within ice cores can be an analytical challenge. Using Fourier transform ion cyclotron resonance mass spectrometry with electrospray ionization, we have characterized, at an unprecedented molecular level, the organic material in an ice core collected from Franz Josef Land (Russia). Several thousand distinct molecular species are identified and provide clues to the principal sources of the organic matter. Humic‐like substances have been identified in both modern and ancient ice, despite the remote marine setting of the ice field. Species containing sulfur heteroatoms are far more abundant in the modern ice, indicating that anthropogenic sulfur emissions are also present in the high–molecular weight organic compounds preserved in ice.
Negative atmospheric ions and their potential role in ion‐induced nucleation
Authors: Eisele F. L. , Lovejoy E. R. , Kosciuch E. , Moore K. F. , Mauldin R. L. , Smith J. N. , McMurry P. H. , Iida Kenjiro
Published: February 2006

Mass identified ion cluster distributions were measured under ambient atmospheric conditions and compared with model predictions based on laboratory ion cluster thermodynamics data. The results are shown from several days where atmospheric sulfur concentrations were high and thus ion‐induced cluster growth was anticipated. Atmospheric gas phase sulfuric acid, temperature, relative humidity, SO2, mobility distributions of ions and small charged particles, and aerosol size distributions were also measured in support of the model calculations. The relative agreement of measurement and model for the first and second sulfuric acid clusters (HSO4−(H2SO4)m) for m = 1 and 2 is quite good but suggests that sulfuric acid clustering may not occur at the collision rate. Clusters for higher m values were not observed, which is also consistent with model predictions for the conditions under which measurements were performed. The lack of both observed and predicted large ion clusters is also consistent with the independent measurements of ion mobility distributions and particle size distributions, which showed similar numbers of positively and negatively charged ultrafine particles, suggesting that neither positive nor negative ion‐induced nucleation processes were likely to have contributed significantly to observed new particle formation rates during this study. The relatively low observed concentrations of the bisulfate ion also suggest that the processes leading to the first sulfuric acid/bisulfate cluster (HSO4−H2SO4) may be more complicated than simple sulfuric acid clustering or exchange reactions. While nucleation was observed on some days, measurements suggest that ion‐induced nucleation did not contribute significantly to new particle production or growth during these events. This does not rule out the possibility that ion‐induced nucleation could contribute significantly to atmospheric new particle formation under very different atmosphere conditions such as in areas with much lower temperatures and higher ion concentrations.
Deposition ice nucleation on soot at temperatures relevant for the lower troposphere
Authors: Dymarska Magdalena , Murray Benjamin J. , Sun Limin , Eastwood Michael L. , Knopf Daniel A. , Bertram Allan K.
Published: February 2006

The ice nucleating efficiency of many important atmospheric particles remains poorly understood. Here we investigate the ice nucleation properties of a range of soot types including soot that has been treated with atmospherically relevant amounts of ozone. We focus on deposition nucleation below water saturation and at temperatures ranging from 243 to 258 K. For our experimental conditions, ice nucleation never occurred at temperatures above 248 K and below water saturation. Below 248 K, ice occasionally formed in our experiments with no indication of the formation of water droplets prior to ice formation. However, even at these temperatures the relative humidity with respect to ice (RHi) was close to water saturation when ice nucleation was observed, suggesting water nucleation may have occurred first followed by ice nucleation during the condensation process. We also performed a complimentary set of experiments where we held soot particles at 248 K and RHi = 124 ± 4%, which is just below water saturation, for a period of 8 hours. From these measurements we calculated an upper limit of the heterogeneous ice nucleation rate coefficient of 0.1 cm−2 s−1. If the number of soot particles is 1.5 × 105 L−1 in the atmosphere (which corresponds to urban‐influenced rural areas), then the number of ice particles produced below water saturation at these conditions is at most 0.1 particles L−1 on the basis of our upper limit. We conclude from our studies that deposition nucleation of ice on most types of soot particles is not important in the Earth's troposphere above 243 K and below water saturation.
Multilevel upscaling through variational coarsening
Authors: MacLachlan Scott P. , Moulton J. David
Published: February 2006

A new efficient multilevel upscaling procedure for single‐phase saturated flow in porous media is presented. While traditional approaches to this problem have focused on the computation of an upscaled hydraulic conductivity, here the coarse‐scale model is created explicitly from the fine‐scale model through the application of operator‐induced variational coarsening. This technique, which originated with robust multigrid solvers, has been shown to accurately capture the influence of fine‐scale heterogeneous structure over the complete hierarchy of coarse‐scale models that it generates. Moreover, implicit in this hierarchy is the construction of interpolation operators that provide a natural and complete multiscale basis for the fine‐scale problem. Thus this new multilevel upscaling methodology is similar to the multiscale finite element method, and indeed, it attains similar accuracy in computations of the fine‐scale hydraulic head and coarse‐scale normal flux on a variety of problems; yet it is an order of magnitude faster on the examples considered here.
Electron cyclotron resonance plasma source by using Ku-band traveling-wave tube amplifier for broad ion-beam processing
Authors: Asaji Toyohisa , Sasaki Hiroshi , Kato Yushi , Sato Fuminobu , Iida Toshiyuki , Saito Junji
Published: February 2006

A new electron cyclotron resonance (ECR) plasma source has been developed for broad ion-beam processing. A Ku-band traveling-wave tube amplifier (11–13GHz) is adopted to generate high-density plasma under low-pressure conditions. An eight-pole magnetic field is selected to improve good uniformity and plasma confinement. The ECR zone for 11GHz microwaves, i.e., 0.393T, is formed within 6.5mm of the inner wall of a chamber. The ECR plasma is generated by low microwave power (∼200W). The radial profile of plasma density and electron temperature is measured with a Langmuir probe. The plasma density is approximately 3×1017m−3 at the microwave power of 200W. The uniformity of the density is within ±12.6% over 140mm in diameter.
Status report of the 28GHz superconducting electron cyclotron resonance ion source VENUS (invited)
Authors: Leitner D. , Lyneis C. M. , Loew T. , Todd D. S. , Virostek S. , Tarvainen O.
Published: February 2006

The superconducting versatile electron cyclotron resonance (ECR) ion source for nuclear science (VENUS) is a next generation superconducting ECR ion source designed to produce high-current, high-charge-state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the rare isotope accelerator (RIA) front end, where the goal is to produce intense beams of medium-charge-state ions. Example beams for the RIA accelerator are 15pμA of Kr17+(260eμA), 12pμA of Xe20+ (240eμA of Xe20+), and 8pμA of U28+(230eμA). To achieve these high currents, VENUS has been optimized for operation at 28GHz, reaching maximal confinement fields of 4 and 3T axially and over 2.2T on the plasma chamber wall radially. After a commissioning phase at 18GHz, the source started the 28GHz operation in the summer of 2004. During that ongoing 28GHz commissioning process, record ion-beam intensities have been extracted. For instance, measured extracted currents for the low to medium charge states were 270eμA of Xe27+ and 245eμA of Bi29+, while for the higher charge states 15eμA of Xe34+, 15eμA of Bi41+, and 0.5eμA of Bi50+ could be produced. Results from the ongoing 28GHz commissioning as well as results using double-frequency heating with 18 and 28GHz for oxygen and xenon are presented. The effect of the minimum B field on the ion source performance has been systematically measured for 18 and 28GHz. In both cases the performance peaked at a minimum B field of about 80% of the resonance field. In addition, a strong dependence of the x-ray flux and energy on the minimum B field value was found.
Rigorous bra-ket formalism and wave function operator for one particle quantum mechanics
Authors: Bergeron H.
Published: February 2006

Following previous works dedicated to the mathematical meaning of the “bra-ket” formalism [I. M. Gel’fand and G. E. Shilov, Generalized Functions (Academic, New York, 1964), Vol. I; J. P. Antoine, J. Math. Phys. 10, 53 (1969); Yu. M. Berezanskii, Expansions of Self-adjoint Operators (American Mathematical Society, Providence, RI 1968); E. Prugovečki, J. Math. Phys. 14, 1410 (1973); J. P. Antoine and A. Grossmann, J. Funct. Anal. 23, 369 (1976); 23, 379 (1976)], we develop a new rigorous mathematical approach, based on an operator representation of bras and kets. This leads to a formalism very similar to second quantization. Well-defined operators associated with local observables can be exhibited, intimately related to previous works of E. Prugovečki [Stochastic Quantum Mechanics and Quantum Space-Time (Reidel, Dordrecht, 1986)].
Force interaction of high pressure glow discharge with fluid flow for active separation control
Authors: Roy Subrata , Gaitonde Datta V.
Published: February 2006

Radio frequency based discharges at atmospheric pressures are the focus of increased interest in aerodynamics because of the wide range of potential applications including, specifically, actuation in flows at moderate speeds. Recent literature describing promising experimental observations, especially on separation control, has spurred efforts in the development of parallel theoretical modeling to lift limitations in the current understanding of the actuation mechanism. The present effort demonstrates higher fidelity first-principle models in a multidimensional finite-element framework to predict surface discharge-induced momentum exchange. The complete problem of a dielectric barrier discharge at high pressure with axially displaced electrodes is simulated in a self-consistent manner. Model predictions for charge densities, the electric field, and gas velocity distributions are shown to mimic trends reported in the experimental literature. Results show that a residual of electrons remains deposited on the dielectric surface downstream of the exposed powered electrode for the entire duration of the cycle and causes a net electric force in the direction from the electrode to the downstream surface. For the first time, results document the mitigation process of a separation bubble formed due to flow past a flat plate inclined at 12° angle of attack. This effort sets the basis for extending the formulation further to include polyphase power input in multidimensional settings, and to apply the simulation method to flows past common aerodynamic configurations.
Transition between nonthermal and thermal ablation of metallic targets under the strike of high-fluence ultrashort laser pulses
Authors: Yang J. , Zhao Y. , Zhu X.
Published: February 2006

The mutual transition dynamics between nonthermal and thermal dominant ablation processes is investigated in the hole-drilling and line-scribing experiments on aluminum samples with intense 50 fs to 24 ps laser pulses. It is found that a critical pulse width that separates the two different ablation regimes monotonically reduces with the increasing laser fluence. Theoretical analyses suggest that the complex interplay between photomechanical stress fragmentation and phase explosion could be responsible for these observations. A semiempirical transition law between the two ablation regimes is introduced, which is consistent with measured experimental data.
Large-order behavior of the perturbation energies for the hydrogen atom in magnetic field
Authors: Zamastil J. , Skála L.
Published: February 2006

Large-order behavior for the perturbation energies of the hydrogen atom in magnetic field is derived. By means of the dispersion relations, the large-order behavior of the series is determined by calculating the lifetime of the quasistationary states in an imaginary magnetic field. This problem is treated by means of the modified multidimensional WKB method. The asymptotic formula for the perturbation energies derived by Avron is generalized to the states with an arbitrary degeneracy. The first order correction to the resulting formula is also found. Thus, the multidimensional WKB method is for the first time explicitly carried out beyond the leading approximation. The analytical results are verified numerically and an excellent agreement between the two is found. The connection between our and conventional semiclassical approximation is also briefly discussed.
Smooth discrete track media fabricated by focused ion beam
Authors: Pang B. S. H. , Chen Y. J. , Leong S. H.
Published: February 2006

We have successfully fabricated discrete track media reproducibly using the focused ion beam (FIB). 1 pA and 10 pA FIB beam currents were used effectively for discrete track fabrication; at Ga+ doses of ∼4.2×1016ions∕cm2 and below, media magnetic properties are effectively suppressed, whilst damage to the morphology was minimal. Larger land/groove magnetic contrast was achieved through increasing the ion bombardment rates within this range. Beyond this dosage range, magnetic suppression leveled out, and physical grooves were etched in the media.
The role of molecular rotation in activated dissociative adsorption on metal surfaces
Authors: Rivière P. , Salin A. , Martín F.
Published: February 2006

The role of molecular rotation in dissociative adsorption of H2 on the activated NiAl(110) metal surface is systematically investigated by means of classical dynamics calculations performed on ab initio six-dimensional potential energy surfaces. The calculations show that molecules rotate abruptly when they are close to the surface and that this rotation allows the molecules to adopt the orientation that is more convenient for dissociation (i.e., nearly parallel to the surface). Also, in reactive sectors of the NiAl(110) unit cell, there is an “angular threshold” below which molecules cannot dissociate. This angular threshold goes down as the incidence energy increases, which explains the rise of the dissociation probability and the fact that it reaches a value close to 1 at incidence energies of the order of 2eV. The fact that switching on molecular rotation favors dissociation establishes a competition between dissociation and rotational excitation of reflected molecules above the dissociation threshold. Measurements on rotational excitation might thus bring indirect evidence on the dissociation dynamics. Sample calculations for nonactivated Pd(111) and activated Cu(110) metal surfaces suggest that some of these conclusions may be of general validity.
Lowering critical cooling rate for forming bulk metallic glass
Authors: Shen T. D. , Schwarz R. B.
Published: February 2006

Small volumes of Pd44Ni10Cu26P20 and Pd43.2Ni8.8Cu28P20 were encapsulated in B2O3 and thermally cycled between Tg−60°C and Tl+60°C, where Tg and Tl denote the alloys’ glass transition and liquidus temperatures. After this thermal treatment, the critical cooling rates (CCRs) for glass formation can be lowered by an order of magnitude, resulting in a critical cooling rate significantly lower than that reported for any other glass forming alloy melt. These experiments demonstrate that the CCR is not constant but strongly dependent on the degree of heterogeneous nucleation.
Low pressure hydrogen discharges
Authors: Paunska Ts. , Schlüter H. , Shivarova A. , Tarnev Kh.
Published: February 2006

This article presents a fluid-plasma model of the free-fall regime of maintenance of high-frequency discharges in hydrogen. The obtained results are for the radial profiles of the concentrations and the velocities of electrons, positive H+, H2+, and H3+ ions, negative H− ions, potential of the radial dc electric field, and electron temperature. The importance of the directed motion of the charged particles in the radial dc electric field, the negative ion behavior in the discharge, and the description of the discharge characteristics by continuous radial profiles, which smoothly cover the total cross section of discharge, are stresses. A strong impact of the negative ions on the formation of the self-consistent discharge structure is shown. The discussions are in terms of changing gas pressure and electron concentration at the discharge axis.
Adsorption of polymers on a brush: Tuning the order of the wetting phase transition
Authors: MacDowell Luis G. , Müller Marcus
Published: February 2006

We develop a computational methodology for the direct measurement of a wetting transition and its order via the effective interface potential. The method also allows to estimate contact angles in the nonwet state and to study adsorption isotherms. The proposed methodology is employed in order to study the wetting behavior of polymers on top of a brush consisting of identical polymers. In the absence of long-range forces, the system shows a sequence of nonwet, wet, and nonwet states as the brush density is increased. Including attractive long-range interactions we can make the polymer liquid wet the bush at all grafting densities, and both first- and second-order wetting transitions are observed. The latter case is limited to a small interval of grafting densities where the melt wets the brush in the absence of long-range interactions. Second-order wetting transitions are preceded by a first-order surface transition from a thin to a thick adsorbed layer. The interval of second-order wetting transitions is limited at low grafting densities by a surface critical end point and at high grafting densities by a tricritical wetting point. Our study highlights the rich wetting behavior that results when competing adsorbent-substrate interactions of different scales are tuned over a broad range.
Resolution of identity Dirac-Kohn-Sham method using the large component only: Calculations of g-tensor and hyperfine tensor
Authors: Komorovský Stanislav , Repiský Michal , Malkina Olga L. , Malkin Vladimir G. , Malkin Irina , Kaupp Martin
Published: February 2006

A new relativistic two-component density functional approach, based on the Dirac-Kohn-Sham method and an extensive use of the technique of resolution of identity (RI), has been developed and is termed the DKS2-RI method. It has been applied to relativistic calculations of g and hyperfine tensors of coinage-metal atoms and some mercury complexes. The DKS2-RI method solves the Dirac-Kohn-Sham equations in a two-component framework using explicitly a basis for the large component only, but it retains all contributions coming from the small component. The DKS2-RI results converge to those of the four-component Dirac-Kohn-Sham with an increasing basis set since the error associated with the use of RI will approach zero. The RI approximation provides a basis for a very efficient implementation by avoiding problems associated with complicated integrals otherwise arising from the elimination of the small component. The approach has been implemented in an unrestricted noncollinear two-component density functional framework. DKS2-RI is related to Dyall’s [J. Chem. Phys. 106, 9618 (1997)] unnormalized elimination of the small component method (which was formulated at the Hartree-Fock level and applied to one-electron systems only), but it takes advantage of the local Kohn-Sham exchange-correlation operators (as, e.g., arising from local or gradient-corrected functionals). The DKS2-RI method provides an attractive alternative to existing approximate two-component methods with transformed Hamiltonians (such as Douglas-Kroll-Hess [Ann. Phys. 82, 89 (1974); Phys. Rev. A 33, 3742 (1986)] method, zero-order regular approximation, or related approaches) for relativistic calculations of the structure and properties of heavy-atom systems. In particular, no picture-change effects arise in the property calculations.