bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Stellarator Concept
Authors: Spitzer Lyman 
Published: December 2004

The basic concepts of the controlled thermonuclear program at Project Matterhorn, Princeton University are discussed. In particular, the theory of confinement of a fully ionized gas in the magnetic configuration of the stellarator is given, the theories of heating are outlined, and the bearing of observational results on these theories is described.
Magnetic confinement in the stellarator is based on a strong magnetic field produced by solenoidal coils encircling a toroidal tube. The configuration is characterized by a ``rotational transform,'' such that a single line of magnetic force, followed around the system, intersects a cross-sectional plane in points which successively rotate about the magnetic axis. A theorem by Kruskal is used to prove that each line of force in such a system generates a toroidal surface; ideally the wall is such a surface. A rotational transform may be generated either by a solenoidal field in a twisted, or figure-eight shaped, tube, or by the use of an additional transverse multipolar helical field, with helical symmetry.
Plasma confinement in a stellarator is analyzed from both the macroscopic and the microscopic points of view. The macroscopic equations, derived with certain simplifying assumptions, are used to show the existence of an equilibrium situation, and to discuss the limitations on material pressure in these solutions. The single-particle, or microscopic, picture shows that particles moving along the lines of force remain inside the stellarator tube to the same approximation as do the lines of force. Other particles are presumably confined by the action of the radial electric field that may be anticipated.
Theory predicts and observation confirms that initial breakdown, complete ionization, and heating of a hydrogen or helium gas to about 106 degrees K are possible by means of a current parallel to the magnetic field (ohmic heating). Flow of impurities from the tube walls into the heated gas, during the discharge, may be sharply reduced by use of an ultra-high vacuum system; some improvement is also obtained with a divertor, which diverts the outer shell of magnetic flux away from the discharge. Experiments with ohmic heating verify the presence of a hydromagnetic instability predicted by Kruskal for plasma currents greater than a certain critical value and also indicate the presence of other cooperative phenomena. Heating to very much higher temperatures can be achieved by use of a pulsating magnetic field. Heating at the positive-ion cyclotron resonance frequency has been proposed theoretically and confirmed observationally by Stix. In addition, an appreciable energy input to the positive ions should be possible, in principle, if the pulsation period is near the time between ion-ion collisions or the time required for a positive ion to pass through the heating section (magnetic pumping).
High-Altitude Atmospheric Density
Authors: Sterne Theodore E. 
Published: December 2004

Atmospheric density values obtained from the motion of artificial earth satellites, at altitudes between 186 and 656 kilometers, are discussed. There is some doubt about the reliability of densities from satellites because of the effects of ionization and, in the case of nonspherical satellites, because of their orientation. Densities inferred from satellites are higher than for the ARDC model of the atmosphere. These densities are about ten times higher than densities inferred from rocket-borne ionization gauges between 186 and 230 kilometers.
The inference of atmospheric density from rocket-borne ionization gauges is discussed critically, and densities so obtained are considered to be inferior in reliability to the satellite densities. The satellite densities suggest molecular scale temperatures higher than those of the ARDC model in one or more regions of altitude above 80 kilometers.
Interaction of the Solar Wind with the Geomagnetic Field
Authors: Parker E. N. 
Published: December 2004

The dynamical properties of the solar wind blowing past the geomagnetic field are investigated by considering the effective viscosity and the resulting transition layer thickness. The collision of ions in the solar wind produces a negligible viscosity in the flow past the geomagnetic field, but such an inviscid flow is shown to be unstable. The resulting disordered interface between the field and the wind yields Fermi acceleration of ions and consequently a not insignificant effective viscosity. The Fermi acceleration results in suprathermal ions which may have an energy spectrum like that observed for primary auroral protons.
The auroral zones and the agitated nature of the polar geomagnetic field are shown to follow from the depth of penetration of the solar wind into the geomagnetic field. The injection of gas into the geomagnetic field is studied. The effect at Earth of the distortion of the outer boundary of the geomagnetic field is computed; no matter how unevenly and anisotropically the outer field is distorted, the effect at Earth is a nearly uniform perturbation field which is closely parallel to the geomagnetic axis. Pushing in on the outer field increases the horizontal component at Earth, and pulling out decreases it; the total increase of the horizontal component is the algebraic sum of all the pushing and pulling. The simultaneous world-wide onset and the main phase of a geomagnetic storm follow.
The common tendency of large and/or violent bodies of plasma to produce suprathermal particles is noted and suggested to be a general dynamical property.
Propagation of Ordinary Sound in Liquid Helium near the λ Point
Authors: Chase C. E. 
Published: December 2004

The velocity and attenuation of ordinary sound in liquid helium have been measured at a frequency of 1 Mc/sec in the neighborhood of the λ point. By using measuring techniques of high resolution, it was possible to observe the behavior in this region in considerable detail. The velocity passes through a minimum approximately 2 × 10−4 °K below the λ point; the maximum attenuation occurs about 8 × 10−5 °K below Tλ. Both velocity and attenuation behave in a manner characteristic of a relaxation process, with the relaxation time a rapid function of temperature near Tλ. The results below Tλ can be described with good quantitative accuracy if this relaxation time is given by τ = 8.8 × 10−12(Tλ − T)−1.
Excess attenuation is also observed above the λ point; this cannot be explained by the above relaxation process. The experimental uncertainties are so large in helium I that no reliable conclusions can be reached, but there is some indication that the quantity α/ω2 is not independent of frequency in this region.
The behavior of the velocity is considered with regard to the Ehrenfest relations, and it is shown that the discontinuity in isothermal compressibility which those relations predict must be almost entirely due to a discontinuity in γ. No contradiction of the Ehrenfest relations is implied, since present knowledge of γ suggests that a discontinuity of the required magnitude may indeed occur.
Rapid Detection of Group B Streptococcus and Escherichia coli in Amniotic Fluid Using Real‐Time Fluorescent PCR
Authors: Straka Michele , Cruz Wifred Dela , Blackmon Camille , Johnson Oswald , Stassen Sara , Streitman David , Golden Stephen , Stamilio David 
Published: December 2004

Objective: To establish reliability and validity of real‐time fluorescent PCR for early detection of bacterial
invasion of the amniotic cavity.Methods: Amniotic fluid samples from 40 patients undergoing mid‐trimester genetic amniocentesis were
incubated for 6 h at 37℃ and were cultured on media specific for group B streptococcus (GBS) and E. coli.
Concurrently, samples were analyzed with real‐time fluorescent PCR (Roche LightCycler) using DNA primers
and probes designed to detect the CAMP factor encoding cfb gene and uidA gene of GBS and E. coli,
respectively. For positive control and to simulate amniotic fluid colonization, 104 cfu/ml of GBS and E. coli were
inoculated on sterile amniotic fluid and incubated for 6 h. Bacterial genomic DNA for the two organisms was
extracted and purified via the two‐step precipitation method using a commercial kit. The real‐time PCR assays
were also tested against 25 non‐GBS and non‐E. coli bacterial species. The lower limit of detection for each
pathogen was established using serial dilution of bacterial genomic DNA.Results: All patient samples were negative for evidence of GBS and E. coli with both culture and real‐time PCR
methods. Amniotic fluid samples inoculated with GBS and E. coli were positive with real‐time PCR whereas the
25 bacterial species other than GBS or E. coli tested negative with the assay. Average total sample processing
time including the pre‐enrichment step was 7 h 40 min. The average cost for DNA extraction and PCR testing
was $8.50 per test.Conclusion: Real‐time fluorescent PCR is a valid and reliable method for detection of specific pathogens in
amniotic fluid. This technique is sensitive for low inoculation levels. Real‐time fluorescent PCR has potential to
impact clinical management as a rapid, reliable detection method for GBS and E. coli in chorioamnionitis.
German‐learning infants’ ability to detect unstressed closed‐class elements in continuous speech
Authors: Höhle Barbara , Weissenborn Jürgen 
Published: December 2004

AbstractThe paper reports on two experiments with the head turn preference method which provide evidence that already at 7 to 9 months, but not yet at 6 months, German‐learning infants do recognize unstressed closed‐class lexical elements in continuous speech. These findings support the view that even preverbal children are able to compute at least phonological representations for closed‐class functional elements. They also suggest that these elements must be available to the language learning mechanisms of the child from very early on, allowing the child to make use of the distributional properties of closed‐class lexical elements for further top‐down analysis of the linguistic input, e.g. segmentation and syntactic categorization.
Children extend both words and non‐verbal actions to novel exemplars
Authors: Childers Jane B. , Tomasello Michael 
Published: December 2004

Abstract Markson and Bloom (1997) found that some learning processes involved in children's acquisition of a new word are also involved in their acquisition of a new fact. They argued that these findings provided evidence against a domain‐specific system for word learning. However, Waxman and Booth (2000) found that whereas children quite readily extend newly learned words to novel exemplars within a category, they do not do this with newly learned facts. They therefore argued that because children did not extend some facts in a principled way, word learning and fact learning may result from different domain‐specific processes. In the current study, we argue that facts are a poor comparison in this argument since facts vary in whether they are tied to particular individuals. A more appropriate comparison is a conventional non‐verbal action on an object –‘what we do with things like this’– since they are routinely generalized categorically to new objects. Our study shows that 21/2‐year‐old children extend novel non‐verbal actions to new objects in the same way that they extend novel words to new objects. The findings provide support for the view that word learning represents a unique configuration of more general learning processes.
A Spoken Dialogue System for Navigation in Non‐Immersive Virtual Environments
Authors: McNeill M.D.J. , Sayers H. , Wilson S. , Mc Kevitt P. 
Published: December 2004

Abstract Navigation is the process by which people control their movement in virtual environments and is a corefunctional requirement for all virtual environment (VE) applications. Users require the ability to move, controllingorientation, direction of movement and speed, in order to achieve a particular goal within a VE. Navigation israrely the end point in itself (which is typically interaction with the visual representations of data) but applicationsoften place a high demand on navigation skills, which in turn means that a high level of support for navigationis required from the application. On desktop systems navigation in non‐immersive systems is usually supportedthrough the usual hardware devices of mouse and keyboard. Previous work by the authors shows that many usersexperience frustration when trying to perform even simple navigation tasks — users complain about getting lost,becoming disorientated and finding the interface `difficult to use'. In this paper we report on work in progressin exploiting natural language processing (NLP) technology to support navigation in non‐immersive virtualenvironments. A multi‐modal system has been developed which supports a range of high‐level (spoken) navigationcommands and indications are that spoken dialogue interaction is an effective alternative to mouse and keyboardinteraction for many tasks. We conclude that multi‐modal interaction, combining technologies such as NLP withmouse and keyboard may offer the most effective interaction with VEs and identify a number of areas where furtherwork is necessary. ACM CSS: I.3.6 Computer Graphics Methodology and Techniques—Interaction and Techniques, I.3.7 Three‐DimensionalGraphics and Realism—Virtual Reality, I.2.7 Natural Language Processing—Speech Recognitionand Synthesis
Creation and Control of Real‐time Continuous Level of Detail on Programmable Graphics Hardware
Authors: Southern Richard , Gain James 
Published: December 2004

AbstractContinuity in level of detail sequences is essential in hiding visual artefacts that occur when switching between discrete levels of detail. However, construction and implementation of these sequences is prohibitively complex. We present a new structure, the g‐mesh, which greatly simplifies the implementation of continuous level of detail in large scenes. We also introduce a novel greedy predictive level of detail control system suited to the g‐mesh. Finally we achieve a dramatic improvement in the rendering of morphing sequences by exploiting current graphics hardware.ACM CSS:I.3.5 Computational Geometry and Object Modeling—Geometric Transformations, Object Hierarchies, I.3.6 Methodology and Techniques—Graphics Data Structures
Quad/Triangle Subdivision
Authors: Stam Jos , Loop Charles 
Published: December 2004

Abstract In this paper we introduce a new subdivision operator that unifies triangular and quadrilateral subdivision schemes. Designers often want the added flexibility of having both quads and triangles in their models. It is also well known that triangle meshes generate poor limit surfaces when using a quad scheme, while quad‐only meshes behave poorly with triangular schemes. Our new scheme is a generalization of the well known Catmull‐Clark and Loop subdivision algorithms. We show that our surfaces are

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everywhere and provide a proof that it is impossible to construct such a

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scheme at the quad/triangle boundary. However, we provide rules that produce surfaces with bounded curvature at the regular quad/triangle boundary and provide optimal masks that minimize the curvature divergence elsewhere. We demonstrate the visual quality of our surfaces with several examples. ACM CSS: I.3.5 Computer Graphics—Curve, surface, solid, and object representations
Wy are the transition paths in China and Eastern Europe different?
Authors: Brezis Elise S. , Schnytzer Adi 
Published: December 2004

AbstractThe purpose of this paper is to provide a framework linking communist regime collapse and privatizing economic reforms. The framework permits us to explain why certain communist regimes lost their monopoly of political power while others have not. We show that the essential difference between those communist regimes which survived economic reform and those which did not, lies in the nature of the privatization reform introduced by the communist leadership. The privatization that we call ‘Market‐Leninist’, was implemented in China and Vietnam while the second type of privatization, termed ‘Embezzlement for a rainy day’ was the type of privatization implemented in Eastern Europe. We show, in the context of a game between rulers and the population, that the size of the repressive apparatus is the key element determining the type of privatization chosen by the rulers.JEL classification: P2, P3.
Consumption smoothing in Russia
Authors: Skoufias Emmanuel 
Published: December 2004

AbstractThis paper uses panel data from rounds V–IX of the Russian Longitudinal Monitoring Survey (RLMS) to examine the extent to which households are able to protect their consumption from fluctuations in their income.It is found that consumption is only partially protected from idiosyncratic shocks to income with food consumption being better protected than non‐food consumption expenditures. This suggests that adjustments in non‐food expenditures may be an important component of the risk management tools of Russian households. The analysis also provides evidence on the extent and nature of the coping strategies adopted by households. It is demonstrated that households complement their self‐insurance strategies, of borrowing, adjusting their labour supply, and selling assets, with informal risk sharing arrangements with households within their community. An examination of the role of sample selection confirmed that these findings are quite robust to this potential source of bias. Furthermore, accounting for the role of measurement and imputation errors in the measure of household income revealed that OLS estimates may yield a misleading picture about the extent to which urban and rural households are insured from idiosyncratic income shocks.JEL classification: D1, R2, P5.
Optimal dynamics of environmental quality in economies in transition1
Authors: Chimeli Ariaster B. 
Published: December 2004

AbstractEnvironmental pressures in the transition economies of the post‐Soviet era affect not only the quality of life for local populations, but also other key economic issues such as privatization and employment by posing obstacles to their progress. Most studies addressing the environment in transition economies are empirical or analyze the effect of environmental protection on economic variables without first establishing an underlying framework together with the optimal path of environmental quality during the transition. This paper presents such a framework and a policy rule for attainment of the optimal balance between capital and environmental quality in economies in transition. Furthermore, the model shows that pollution taxes or tradable pollution permits are by themselves insufficient to implement the social optimum in a decentralized economy. The results of the model are consistent with depressed economic activity in those economies during an initial phase, and with the diversity of environmental policies in both Central and Eastern Europe (CEE) countries and the Newly Independent States (NIS).JEL classification: Q20, P20, O13.
Grammatical analysis of Hindi sentences using connectionist approach
Authors: Prakash Nupur , Garg Kumkum 
Published: December 2004

Abstract:
This paper presents a simple connectionist approach to parsing of a subset of sentences in the Hindi language, using Rule based Connectionist Networks (RBCN) as suggested by Fu in 1993. The basic grammar rules representing Kernel Hindi sentences have been used to determine the initial topology of the RBCN. The RBCN is based on a multilayer perceptron, trained using the backpropagation algorithm. The terminal symbols defined in the language structure are mapped onto the input nodes, the non‐terminals onto hidden nodes and the start symbol onto the single output node of the network structure. The training instances are sentences of arbitrary, but fixed maximum length and fixed word order. A neural network based recognizer is used to perform grammaticality determination and parse tree generation of a given sentence. The network is exposed to both positive and negative training instances, derived from a simple context‐free‐grammar (CFG), during the training phase. The trained network recognizes seen sentences (sentences present in the training set) with 98–100% accuracy. Since a neural net based recognizer is trainable in nature, it can be trained to recognize any other CFG, simply by changing the training set. This results in reducing programming effort involved in parser development, as compared to that of the conventional AI approach. The parsing time is also reduced to a great extent as compared to that of a conventional parser, as a result of the inherent parallelism exhibited by neural net architecture.
ESAS: A case‐based approach to business planning and monitoring
Authors: Frangou Andreas J. , Wan Yan , Antony Jiju , Kaye Mike 
Published: December 2004

Abstract:
Creating and sustaining a competitive advantage in today’s turbulent world markets is a formidable business challenge. For many organisations, operating within an inherently unstable external environment has resulted in the need for a cultural rethink. Business complacency, brought about by corporate industry monopolisation, the reliance on reputation, brand identity, and customer allegiance, is no longer a recipe for sustained market growth. Companies have realised that being market focused could provide them with a competitive edge within the marketplace. To achieve this organisations have turned to the ‘Quality movement’, embracing the Total Quality Management (TQM) philosophy and its inherent tools (auditing frameworks, concept of quality systems etc.) as a means to recapture lost ground.
ESAS (Enterprise Strategic Advisory System) is a prototype intelligent system that utilises a case‐ based approach to address the issues raised above, by providing organisations with advice on market‐ led quality and competitive strategy. This paper explores the philosophy and ideas behind the ESAS concept, and describes the development of an ESAS prototype.
Scale of Operations and Locus of Control in Market‐ Versus Mission‐Oriented Charter Schools*
Authors: Brown Heath , Henig Jeffrey , Lacireno‐Paquet Natalie , Holyoke Thomas T. 
Published: December 2004

Objective.The objective of this article is to investigate two distinct strands in the charter school movement: one that emphasizes school‐based management and another that emphasizes market efficiency. We were interested in whether charter schools that were founded or co‐founded by for‐profit education management organizations (EMOs) tend to pursue economies of scale and are less likely than others to implement school‐level decision making in key areas.Methods.The analysis uses data drawn from a survey we conducted of the population of charter schools in Arizona, Michigan, Pennsylvania, and Washington, DC.Results.We find that charter schools that were founded or co‐founded by EMOs tend to be larger and areless likelyto exhibit decision‐making control at the school level.Conclusions.Our analysis underscores the importance of disaggregating the charter school phenomenon into its distinct constituent parts in order to draw meaningful lessons from this evolving and significant experiment in alternative education delivery mode.