bluuebunny/crossref_metadata_2025 huggingface dataset:
'Tis all in pieces (separate RFs and CFs), all coherence gone
Authors: Neibur Ernst , Usher Marius
Published: July 2002

We argue that the separation between CF (contextual field) and
RF (receptive field) in relation to the NMDA (N-methyl-D-aspartate)
system is empirically questionable and that it is functionally
unnecessary. In addition, the proposed suppression of unexpected
information will in many cases be counterproductive.
Area, surface, and contour: Psychophysical correlates of three classes of pictorial completion
Authors: Dresp Birgitta
Published: July 2002

A simple working taxonomy with three classes of pictorial
completion is proposed as an alternative to Pessoa et al.'s
classification: area, surface, and contour completion. The
classification is based on psychophysical evidence, not on the
different phenomenal attributes of the stimuli, showing that
pictorial completion is likely to involve mechanistic interactions
in the visual system at different levels of processing. Whether
the concept of “filling-in” is an appropriate metaphor
for the visual mechanisms that may underlie perceptual completion
is questioned.
Content without a frame? The role of vocabulary biases in speech errors
Authors: Harley Trevor A.
Published: July 2002

Constraints on the types of speech errors observed can be
accounted for by a frame/content distinction, but connectionist
modeling shows that they do not require this distinction. The
constraints may arise instead from the statistical properties of
our language, in particular, the sequential biases observed in
the vocabulary. Nevertheless, there might still be a role for the
frame/content distinction in syntactic planning.
A biased survey and interpretation of the nature–nurture literature
Authors: Gagné Françoys
Published: July 2002

This commentary samples some of the major bodies of
counterevidence omitted by Howe et al., including the strong
relationship between IQ and academic excellence, the limited
effects of early stimulation programs, and the measurement of
musical aptitudes. The authors' selective review and analysis of
the surveyed literature, especially studies of prodigies and in
behavioral genetics, is discussed.
Feature learning, multiresolution analysis, and symbol grounding
Authors: MacDorman Karl F.
Published: July 2002

Cognitive theories based on a fixed feature set suffer from
frame and symbol grounding problems. Flexible features and other
empirically acquired constraints (e.g., analog-to-analog mappings)
provide a framework for letting extrinsic relations influence symbol
manipulation. By offering a biologically plausible basis for feature
learning, nonorthogonal multiresolution analysis and dimensionality
reduction, informed by functional constraints, may contribute to a
solution to the symbol grounding problem.
Explanatory force, antidescriptionism, and the common structure of substance concepts
Authors: Schröder Jürgen
Published: July 2002

Millikan's proposal of a common structure of substance
concepts does not explain certain conspicuous findings in the
psychological literature such as typicality effects, the context
sensitivity of these effects, and slips of the tongue. Moreover, it is
unclear how antidescriptionism could be relevant to psychological
theorizing. Finally, it does not seem to be true that concepts of
individuals, stuff, and real kinds have a common structure in older
children and in adults.
Filled-in sensations: The primordial species of imagery?
Authors: Sauvé Kevin
Published: July 2002

Filled-in sensations exhibit a distinctive
mélange of causal features, resembling
perceptual sensations in some respects and imagery in others.
This commentary identifies several of these shared causal
features and advances the hypothesis that filled-in sensations
may constitute the primordial species of imagery, the evolutionary
neurofunctional precursor of paradigmatic forms of imagery.
Talent: Don't confuse necessity with sufficiency, or science with policy
Authors: Winner Ellen
Published: July 2002

Howe et al. fail to provide evidence that practice is
sufficient and ignore evidence of high ability before
instruction. They unsuccessfully discount savants; provide weak
evidence against heritability of music, criticize retrospective
evidence selectively, using it when it supports their position; and
ultimately both accept and deny talent. Finally, they conflate a
scientific question with one of policy.
Episodic memory, amnesia, and the hippocampal–anterior thalamic axis
Authors: Aggleton John P. , Brown Malcolm W.
Published: July 2002

By utilizing new information from both clinical and
experimental (lesion, electrophysiological, and gene-activation)
studies with animals, the anatomy underlying anterograde amnesia
has been reformulated. The distinction between temporal lobe and
diencephalic amnesia is of limited value in that a common feature
of anterograde amnesia is damage to part of an “extended
hippocampal system” comprising the hippocampus, the fornix,
the mamillary bodies, and the anterior thalamic nuclei. This view,
which can be traced back to Delay and Brion (1969), differs from
other recent models in placing critical importance on the efferents
from the hippocampus via the fornix to the diencephalon. These
are necessary for the encoding and, hence, the effective subsequent
recall of episodic memory. An additional feature of this
hippocampal–anterior thalamic axis is the presence
of projections back from the diencephalon to the temporal
cortex and hippocampus that also support episodic memory.
In contrast, this hippocampal system is not required for tests
of item recognition that primarily tax familiarity judgements.
Familiarity judgements reflect an independent process that depends
on a distinct system involving the perirhinal cortex of the temporal
lobe and the medial dorsal nucleus of the thalamus. In the large
majority of amnesic cases both the hippocampal–anterior
thalamic and the perirhinal–medial dorsal thalamic systems
are compromised, leading to severe deficits in both recall and
recognition.
The developmental progression from implicit to explicit knowledge: A computational approach
Authors: Alibali Martha Wagner , Koedinger Kenneth R.
Published: July 2002

Dienes & Perner (D&P) argue that nondeclarative
knowledge can take multiple forms. We provide empirical support
for this from two related lines of research about the development
of mathematical reasoning. We then describe how different forms
of procedural and declarative knowledge can be effectively modeled
in Anderson's act-r theory, contrasting this computational
approach with D&P's logical approach. The computational
approach suggests that the commonly observed developmental progression
from more implicit to more explicit knowledge can be viewed as
a consequence of accumulating and strengthening mental representations.
Words do not stand alone: Do not ignore a word's role when examining patterns of activation
Authors: Greenberg Seth N. , Nisslein Monika
Published: July 2002

Pulvermüller traces the differences in brain activity
associated with function and content words. The model considers
words displayed primarily in isolation. Research on letter detection
suggests that what distinguishes function from content words are their
roles in text. Hence a model that fails to consider context effects on
the processing of words provides an insufficient accounting of word
representation in the brain.
Constraining the use of constraints
Authors: Dannemiller James L. , Epstein William
Published: July 2002

Pylyshyn uses constraints to solve many of the problems
associated with the inverse problem in vision. We are sympathetic to
such an approach, and indeed, we think that in many cases constraints
allow tract-able solutions to otherwise insoluble problems. We argue,
however, that Pylyshyn has been too quick to assume that certain
perceptual phenomena can be explained by appealing to constraints
embodied in the visual machinery. For several more complex perceptual
phenomena it is not clear how one proceeds to look for constraints
once simple constraints like rigidity have been abandoned.
Simulations, simulators, amodality, and abstract terms
Authors: Mitchell Robert W. , Clement Catherine A.
Published: July 2002

Barsalou's interesting model might benefit from defining
simulation and clarifying the implications of prior critiques for
simulations (and not just for perceptual symbols). Contrary to claims,
simulators (or frames) appear, in the limit, to be amodal. In addition,
the account of abstract terms seems extremely limited.
Out of sight but not out of mind: Isomorphism and absent qualia
Authors: Van Gulick Robert
Published: July 2002

The isomorphism constraint places plausible limits on the use of third-person evidence to explain color experience but poses no difficulty for functionalists; they themselves argue for just such limits. Palmer's absent qualia claim is supported by neither the Color Machine nor Color Room examples. The nature of color experience depends on relations external to the color space, as well as internal to it.
Symmetric and reversible families of vector fields near a partially hyperbolic singularity
Authors: BONCKAERT PATRICK
Published: July 2002

We study smooth local models of families of symmetric and reversible vector fields near a partially hyperbolic singularity. Special attention is given to the question of whether the involved changes of variables commute with the symmetry.
Torus homeomorphisms whose rotation sets have empty interior
Authors: JONKER LEO B. , ZHANG LEI
Published: July 2002

Let $F$ be a lift of a homeomorphism $f: {\Bbb T}^{2} \to {\Bbb T}^{2}$ homotopic to the identity. We assume that the rotation set $\rho(F)$ is a line segment with irrational slope. In this paper we use the fact that ${\Bbb T}^2$ is necessarily chain transitive under $f$ if $f$ has no periodic points to show that if $v \in \rho(F)$ is a rational point, then there is a periodic point $x \in {\Bbb T}^{2}$ such that $v$ is its rotation vector.
Subcontinua of the closure of the unstable manifold at a homoclinic tangency
Authors: BARGE MARCY , DIAMOND BEVERLY
Published: July 2002

Suppose that $F$ is a $C^\infty$ diffeomorphism of the plane with hyperbolic fixed point $p$ for which a branch of the unstable manifold, $W^u_+(p)$, has a same-sided quadratic tangency with the stable manifold, $W^s(p)$. If the eigenvalues of $DF$ at $p$ satisfy a non-resonance condition, each nonempty open set of $ \cl( W^u_+(p))$ contains a copy of any continuum that can be written as the inverse limit space of a sequence of unimodal bonding maps.
Postcommunist studies: once again through the looking glass (darkly)?
Authors: SAKWA RICHARD
Published: July 2002

Discussion of what is ‘(post)-Soviet studies’ has become one of the most lively sub-fields of the discipline (if, indeed, it is a discipline), reflecting the mood of introspection and self-doubt that prevails in the area today. What precisely, is the subject in question? There is no consensus even over the name. The title of this short review was initially set as ‘post-Soviet studies’. Although from the outset aware of the shortcomings of the term, it was only as I began to think how to approach the subject that I realised that it was impossible—or at least profoundly misleading—to work under such a rubric. The concept of ‘Soviet’ grounds the emerging discipline too narrowly in the experience of a single country. The notion of ‘post-Sovietology’ is also emerging as a contender to describe the field, but that is doubly misleading, inheriting at best a mixed intellectual baggage and controversial legacy of the original subject of ‘Sovietology’, now compounded by the addition of the prefix ‘post’. The subject is indeed as much about the terms it uses and the methodologies it applies as it is about the events and processes it describes.
Hybridity and national musics: the case of Irish rock music
Authors: Mclaughlin Noel , Mcloone Martin
Published: July 2002

Introduction: Irishness and the ‘gift of song’

A key element in the range of stereotypes characteristically assigned to the Irish has been their natural proclivity for music and song, a feature of colonial discourse that can be traced back even to the Norman invasions of the twelfth century. However, the powerful link between the Irish and musicality (along with a host of other, considerably less attractive traits) was finally consolidated in the Victorian era at the height of the British imperial project (Curtis 1971; Busteed 1998). Irish music by this stage was constructed as a specific ethnic category based on the assumption that there was an identifiably Irish musical style that existed as an expression of the people, a reflection of their innate feelings and sensibilities. Music, therefore, became a feature of ‘race’, taking on properties for the coloniser that appeared to transcend the passage of time, that remained fixed and unchanging.
3D Numerical simulation of Rayleigh–Taylor instability
using MAH-3 code
Authors: ANUCHINA N.N. , VOLKOV V.I. , GORDEYCHUK V.A. , ES'KOV N.S. , IIYUTINA O.S. , KOZYREV O.M.
Published: July 2002

A 3D numerical study of the turbulent phase of
the evolution of Rayleigh–Taylor instability (RTI)
was undertaken using the MAH-3 code. A criterion and a
technique have been developed that can be used for diagnostics
in computational experiments studying flow transition to
self-similar turbulence. It has been found that a criterion
of the flow transition to the self-similar turbulence is
Kolmogorov's self-similar distribution of the turbulent
kinetic energy together with the square law of mixing zone
extension. The technique is based on the analysis of the
evolution of the dimensionless power spectrum of specific
kinetic energy. Three phases of nonlinear mixing are found:
“relict chaos”, “formation of classical
energy spectrum” and “spectrum degradation.”
Determination of a proportionality factor for a square
law within the time range incorporating inertial interval
gives the value of α ≈ 0.07.
Numerical simulation by the MAH-3 code of the interfaces
using an unstructured mesh of markers
Authors: VOLKOV V.I. , GORDEYCHUK V.A. , ES'KOV N.S. , KOZYREV O.M.
Published: July 2002

The paper addresses Rayleigh–Taylor instability
(RTI) problems and presents a method of describing an interface
with markers on a Eulerian mesh, which is implemented in
the MAH-3 code. The proposed method allows a more accurate
description of the evolution of the interface caused by
Rayleigh–Taylor perturbations and preserves symmetry
of the interface under appropriate symmetry of the problem
(planar, cylindrical, and spherical). The method employs an
unstructured triangular mesh of makers. Method capabilities
are demonstrated on 2D and 3D Rayleigh–Taylor instability
problems.
2D numerical modeling of pulsed plasma acceleration by a
magnetic field
Authors: KONDRATYEV A.A.
Published: July 2002

Pulsed plasma guns are used to obtain high-velocity
(107–108 cm/s) plasma flows.
Their performance is restricted by an instability of the
plasma acceleration by a magnetic field. This paper presents
results of a 2D numerical study of plasma dynamics in the
plasma gun. The ZENIT-2D code solving the magnetohydrodynamic
(MHD) equations on a fixed Eulerian mesh is used. The plasma
parameters and geometry are chosen to be close to the parameters
of the MK-200 installation (Sidnev et al., 1983).
The influence of the initial distribution of a neutral
gas on accelerator performance is investigated. A brief
description of the code and details of the simulations
are presented. It is shown that the instability of acceleration
leads to turbulent mixing of the plasma and magnetic field
and, correspondingly, to a broader current channel than
that predicted by the classical diffusion with the Spitzer
conductivity. Numerical results are compared with experimental
data (Bakhtin & Zhitlukhin, 1998) displaying a good
qualitative agreement.
π phase-shift induced transparency of resonant gamma
radiation
Authors: HOY G.R. , ODEURS J. , COUSSEMENT R.
Published: July 2002

The so-called gamma-echo effect has been
observed experimentally and analyzed using the semiclassical
optical theory. Here the effect is reinterpreted using
a new 1D quantum mechanical model. This leads to a different
interpretation of the effect as a π phase-shift induced
transparency. In the basic time-differential Mössbauer
spectroscopic technique the forward-scattered recoil-free radiation
is observed, in delayed coincidence, after passing through a
nuclear-resonant absorber. The effect in question is produced
most efficiently when the source of recoil-free radiation is moved
abruptly causing a π phase shift of the source radiation during
its radiative lifetime. Using the 1D model the effect is seen to
arise from the constructive interference between the source radiation
at a later time, and the radiation coming from the absorber excited
at an earlier time. The exact form of the source modulation and the
nuclear-resonant thickness of the resonant absorber determines the
shape of the time-differential resonant gamma ray transmission
spectrum. Numerical results are given using the familiar 57Fe
recoil-free resonant transition. The π phase-shift-induced
transparency allows the resonant gamma radiation, incident on the
resonant absorber, to be transmitted through the absorber without
appreciable attenuation.
The implosion dynamics and emission characteristics of Al
liner-on-wire implosions
Authors: ROSCH R. , FRIART D. , DARRIGOL M. , CHATRIEUX L. , ZEHNTER P. , ROMARY P. , CHEVALIER J.M.
Published: July 2002

Previous experiments at 0.1 TW level have shown
that stability and X-ray emission of fast Z-pinch
could be significantly improved by imploding an Al vapor
jet onto a very thin coaxial wire (Wessel et al.,
1992). Here we present the first results of an Al Z-pinch
using a similar liner but at mega-ampere level. The pinch
is driven by AMBIORIX facility, a 2 TW, 0.5 Ω, 2 MA,
and a 50-ns pulse-line generator. We study the effect of
an Al wire and its diameter (20–50 μm) on the
implosion dynamics, on X-ray yield, on-axis magnetohydrodynamics
(MHD) stability, and on Rayleigh–Taylor instability
of the column at stagnation. Analysis of an Al jet on Al
wire shots demonstrates that X-ray yield due to emission
processes in the H- and He-like ionization stages (i.e.,
the K-shell) is enhanced, relative to the ones
with Al jet only. The wire leads also to a better symmetrization
of the implosion, and to better reproducibility of the
shots. X-ray signals exhibit two similar pulses, 10-ns-wide
and separated by 15 ns. To discern spectrally the origin
of each pulse, further experiments have been performed
with stainless steel wire (25 μm in diameter). Results
show that liner and wire radiate simultaneously and contribute
to both pulses. Full analysis of a typical Al jet on Al
wire shot, using detailed collisional-radiative equilibrium
(CRE) model is given in this paper. A sketch of the pinch
at stagnation, with a cold dense core embedded in a hot
low density corona, reproduces well all features of X-ray
emission.
The motion of a charged particle in the plane, monochromatic
and linear—polarized EM waves and in the presence
of a constant magnetic or electric fields
Authors: DUBIK A.
Published: July 2002

On the basis of the Lorentz equation the analytical
solution of the equations of motion of a charged particle
in the electromagnetic (EM) waves combined with constant
electric or magnetic fields has been found. The possibility
of controlling of the parameters of motion in velocity
and spatial spaces is discussed as follows.
Nonlinear electromagnetic phenomena in the relativistic
interaction of ultrahigh intensity laser pulses with plasmas
Authors: PEGORARO F. , BULANOV S.V. , CALIFANO F. , ESIRKEPOV T.ZH. , LISEIKINA T.V. , NAUMOVA N.M. , RUHL H. , VSHIVKOV V.A.
Published: July 2002

2D, low-frequency, relativistic solitary waves
have been found recently in 2D. Particle-in-cell simulations
of ultraintense laser pulses propagating in underdense
plasmas, in regimes where the laser pulse undergoes energy
depletion and downshifting of its frequency. These slowly
propagating, spatially localized, electromagnetic structures
represent an important channel of energy conversion from
the laser pulse to the plasma. Pulse energy can also be
converted into fast propagating structures, associated with
collimated beams of ultrarelativistic electrons. Lienard–Wiechert
magnetic field structures have been observed in PIC simulations
to move together with focalized ultrarelativistic electron
beams in the plasma.
Unusual fragmentation patterns from the dissociation of
some small molecules
Authors: GRAHAM P. , FANG X. , LEDINGHAM K.W.D. , SINGHAL R.P. , McCANNY T. , SMITH D.J. , KOSMIDIS C. , TZALLAS P. , LANGLEY A.J. , TADAY P.F.
Published: July 2002

The nonlinear interaction of molecular matter with
the intense field of a linearly-polarized laser beam, allows
the study of not only the ionization dynamics of the parent
molecule, but also the angular distribution of the exploding
fragments. This is carried out by rotating the polarization
vector of the laser with respect to the laboratory reference
frame. The angular distributions for the CS2,
CO2, N2O, H2S, and CH3I
molecular ions, at intensities of about 1016
W cm−2, are presented. The distributions
seem to be dependent on the molecule under consideration,
but common features are that the peripheral atoms of the
molecule are ejected along the ToF-axis, and the central
atom perpendicularly to it, whenever the polarization vector
and ToF-axis are collinear. It would seem that the distributions
for the lighter of the molecules are partly due to alignment
via dipole moments induced by the laser, as the
distributions narrow as their charge-state increases. This
is indicative of a larger torque acting on the higher-charged
precursor molecular ion, via the interaction of
the field with the laser-induced dipole moment. On the
other hand, the angular dependence of the heavier molecules
studied, are thought to originate from a dependence of
the ionization/dissociation probability of the molecular
ion on the initial angle made between the molecular axis
and the polarization vector, that is, a preferential ionization/dissociation
process. Spatial alignment in the laser pulse, in this
case, is not thought to occur since the peaks do not narrow
as the ionic charge increases. Finally, the results for
H2S and also N2O are particularly
interesting, since distributions for up to S7+
are presented, while the N-distributions show
both a parallel and perpendicular component of the distribution.
Neither of these results has, to the author's knowledge,
been previously observed.
Beyond the moving mirror model: Attosecond pulses from a
relativistically moving plasma
Authors: ROSO L. , PLAJA L. , RZAZEWSKI K. , VON DER LINDE D.
Published: July 2002

A simple model is proposed to study the field generated
by a 3D plasma layer. The model neglects electron–electron
interactions in the same way as occurs in the well known
moving mirror models. However, the present model considers
the radiation emitted by the moving electrons in a more
precise way than in the mirror models, and allows the study
of underdense or near critical plasmas. Results, including
the transverse intensity profile of the driving field,
are presented that show the possibility of generating trains
of attosecond pulses.
First applications of the ballistic model in femtosecond
laser–matter interaction: Preliminary evidence of
ac-run-away and new features about normal skin effect
Authors: BÉSUELLE E. , TEYCHENNÉ D. , SALOMAA R.R.E.
Published: July 2002

The role of collisional absorption is supposed to be
important in the beginning of the interaction between a
laser pulse and matter. Later on, collective absorption
phenomenons take place. The scope of this paper is to present
first results about the so-called AC-run-away
effect, defined as a “sudden transition from collisional
absorption regime to a collective one.” For this
purpose, we use a simple model based on ballistic theory.
The delicate point concerning the Coulomb logarithm is
also studied: we propose for it a convenient cutoff and
an ensemble averaged Coulomb logarithm fit formula. Another
application of the model presented here is the normal skin
effect. We show some sensible differences between the present
approach and those based on more common and rough collision
frequency formulas.
Review of ICF investigations carried out at the high-power
laser facilities “ISKRA” in 1996–1997
Authors: KOCHEMASOV G.G.
Published: July 2002

A short review of the last 2 years of laser fusion
activity at ISKRA-4 and ISKRA-5 facilities is presented.
The main aim of the report is to describe the advantages
of using spherical hohlraums for investigations of different
types of implosions.
Investigations of ion streams emitted from plasma produced
with a high-power picosecond laser
Authors: BADZIAK J. , KOZLOV A.A. , MAKOWSKI J. , PARYS P. , RYĆ L. , WOŁOWSKI J. , WORYNA E. , VANKOV A.B.
Published: July 2002

This work reports on investigations of parameters
of ion streams emitted from a plasma produced with a picosecond
laser at the power densities ≥1016 W/cm2.
Not many papers dealing with such investigations have been
published up to now, in spite of the fact that the application
of precise corpuscular diagnostics enables better learning
of the physical properties of such a plasma. As a result
of the investigations carried out, the average and maximum
energies of Cu ions were 30 keV and 150 keV, respectively.
The maximum charge of Cu ions was 13+. The dependencies
of parameters of ions emitted from the plasma on the laser-pulse
energy as well as on the location of the focus of the laser
beam with respect to the target's surface were also
found out. The results obtained from the ion measurements
in relation to the results of measurements of X ray are
discussed.
Generation of focused intensities of 5 × 1019
Wcm−2
Authors: DANSON C.N. , ALLOTT R. , BOOTH G. , COLLIER J. , EDWARDS C.B. , FLINTOFF P.S. , HAWKES S.J. , HUTCHINSON M.H.R. , HERNANDEZ-GOMEZ C. , LEACH J. , NEELY D. , NORREYS P. , NOTLEY M. , PEPLER D.A. , ROSS I.N. , WALCZAK J.A. , WINSTONE T.B.
Published: July 2002

The technique of Chirped Pulse Amplification (CPA)
developed by Strickland and Mourou (1985) is now in common
use on many laser systems [see, for instance, the
review by Perry & Mourou (1994)] and has resulted
in massive increases in focused intensities. This paper
describes CPA implementation on the Vulcan laser system
which has generated multi-Joule sub-picosecond pulses whilst
maintaining beam quality to produce focused intensities
of 5 × 1019 Wcm−2.
Stimulated atomic and nuclear processes in short laser pulse
interaction
Authors: BELIAEV VADIM S. , AREFYEV VLADIMIR I.
Published: July 2002

Taking into account the stochastic excitation of
the atoms (as quantum structures), we can suggest an absolutely
new conception of a wide spectrum of processes in a femtosecond
laser produced plasma. The electromagnetic fields being
achieved with the modern laser technique exceed intraatomic
fields by several orders. This fundamentally changes the
physics of their interaction with the atomic structures.
The atom effectively transforms the energy of radiation
falling on it into fluxes on the nucleus. Quantum systems
spin interaction with vector potential field being to play
the essential role.
Hydrodynamic model for UV laser ablation of polymers
Authors: AFANASIEV Y.V. , ISAKOV V.A. , ZAVESTOVSKAYA I.N. , CHICHKOV B.N. , VON ALVENSLEBEN F. , WELLING H.
Published: July 2002

The applicability of hydrodynamic models for theoretical
description of UV laser ablation of polymers is studied.
The plume formation is considered as a first-kind phase
transition. In case of strongly absorbing polymers this
phase transition occurs as a surface evaporation, and in
case of weakly absorbing polymers as a bulk evaporation.
The vapor plume is assumed to be transparent for laser
radiation, and its expansion is described by the isoentropic
hydrodynamic equations. New analytical expressions for
ablation (etch) depths per pulse are obtained, which are
in good agreement with the available experimental data
(Afanasiev et al. 1997).
Evolution of mixing zone under the influence of nonstationary
compression wave
Authors: ZAYTSEV S.G. , KRIVETS V.V. , TITOV S.N. , CHEBOTAREVA E.I.
Published: July 2002

In the present study we performed an experimental
investigation of the Rayleigh–Taylor instability
(RTI) in a mixing zone between two gases entrapped into
accelerated motion by a nonstationary compression wave.
Acceleration g was ∼1.5·107
cm/s2, Atwood numbers ranged from 0.04 to 0.77.
A mixing zone was formed by an oxygen-hydrogen mixture
and an inert gas (Ne, Ar, Kr, Xe) or SF6. The
initial gas pressure was 0.5 atm. A specific feature of
our experiment is compressibility of media tested and initially
continuous interface between gases of different densities.
The present work is a continuation of investigations on
nonlinear, transition, and early turbulent stages of the
RTI.
Microtomography data processing methods for cryogenic target
characterization
Authors: ALEKSANDROVA I.V. , KORESHEVA E.R. , OSIPOV I.E. , GOLOV V.I. , CHTCHERBAKOV V.I.
Published: July 2002

Determining the cryogenic target parameters with
high precision calls for the development of a new direction
in the area of target characterization based on microtomography
methods of data processing. In this report we present our
first results in this area.
Highly charged ions from Nd-laser produced plasma of medium
and high-Z targets
Authors: SHARKOV B. , SHUMSHUROV A. , ROUDSKOY I. , KILPIO A. , SHASHKOV E. , KISELEV N. , PASHININ P.
Published: July 2002

The project ITEP-TWAC (Tera Watt Accumulator) being
in progress at ITEP (Moscow) requires He-like ions for
non-Liouvillean injection into the storage ring to accumulate
≈2·1013 particles with medium masses
up to 59Co25+. Powerful lasers were
found to be the best choice for those ions production.
This work presents the experimental results of highly charge
ion generation in plasmas produced by the second harmonic
of Nd-glass laser facility with a total energy E
≤ 50 J and pulse duration of about 2.5 ns at GPI (Moscow).
Ti and Ta targets were under investigation. An electrostatic
ion energy analyzer and an ion charge collector were used
to measure the ion charge state spectra at a 3-m distance
from the targets. 5·107 He-like Ti ions
per cm2 within 1 μs pulse as well as 107
Ta+41 per cm2 within 0.8 μs were
observed.
A PARAMETRIC CHARACTERIZATION OF INTEGRATED VECTOR AUTOREGRESSIVE
(VAR) PROCESSES
Authors: la Cour Lisbeth
Published: July 2002

This paper provides a polynomial factorization
theorem that is then used to extend the characterization
parts of the parametric representation theorems of Johansen
(1992, Econometric Theory 8, 188–202) for
vector autoregressive processes integrated of up to order
2. A characterization theorem is provided in the general
case of an I(d) process. For the discussion
of the complicated polynomial cointegration properties of
such processes, the case of an I(3) process is
considered as an example.
Seed dispersal in Palicourea rigida, a common treelet species from neotropical savannas
Authors: WÜTHERICH DIRK , AZÓCAR AURA , GARCÍA-NUÑEZ CARLOS , SILVA JUAN F.
Published: July 2002

The dispersal system of Palicourea rigida (Rubiaceae), a common woody species of neotropical savannas,
was studied in a seasonal Venezuelan savanna. Production and consumption of fruits, dispersal agents, feeding behaviour, transport and effects on seed viability, were investigated by field observations, cage experiments and viability
tests. To compare different dispersers, quantitative and qualitative dispersal parameters were calculated. About 59%
of the fruit crop was dispersed successfully by birds. Although 10 different bird species consumed the fruits of
Palicourea rigida, three bird species dispersed 79% of the fruits (Tyrannus melancholicus, Molothrus bonariensis and
Elaenia chiriquensis). T. melancholicus (Tyrannidae) was the most important dispersal agent, with more than 39% of
dispersed seeds. In contrast to the predictions of the specialization vs. generalization paradigm, this system achieves
high effectiveness by means of predominantly unspecialized traits in both the plant and the dispersers.

Se estudió el sistema de dispersión de Palicourea rigida (Rubiaceae), una leñosa común de las sabanas
neotropicales, en una sabana estacional de Venezuela. Mediante observaciones de campo y experimentos en jaulas y
en el laboratorio, se estudiaron paramétros tales como producción, transporte y consumo de frutos, los agentes
dispersores y su comportamiento y los efectos sobre la viabilidad de las semillas. Para comparar los agentes de dispersión
se estimaron paramétros cualitativos y cuantitativos. Cerca del 59% de la cosecha total de frutos fue dispersada
existosamente por pájaros. Aunque los frutos fueron consumidos por diez especies de aves, el 79% de los frutos fueron
dispersados por solamente tres especies (Tyrannus melancholicus, Molothrus bonariensis y Elaenia chiriquensis). T.
melancholicus (Tyrannidae) fue el más importante agente dispersor con más del 39% del total de semillas dispersadas.
En contraste con el paradigma de especialización vs. generalización, este sistema alcanza alta efectividad pero se
caracteriza por rasgos poco especializados, tanto en la planta como en los dispersores.
THE HUMAN SEMANTIC POTENTIAL: SPATIAL LANGUAGE AND
CONSTRAINED CONNECTIONISM.Terry Regier. Cambridge, MA: MIT
Press, 1996. Pp. xvi + 220. $37.50 paper.
Authors: Abbott Barbara
Published: July 2002

The semantic potential referred to in the title of this book is the ability of humans to learn the
(closed-class) terms for basic spatial relations, such as (for English) onto, above, and
through. Regier presents a modified connectionist model of this ability designed to
address three questions: (a) What kind of system can learn spatial terms? (b) How can this
system function without negative evidence? and (c) What are the universal constraints on
learnable spatial terms? The answers suggested to these questions are: (a) a modified
connectionist network—one which incorporates structural constraints motivated by human
physiology; (b) the assumption of mutual exclusion, that is, that different terms have mutually
exclusive denotations; and (c) the structural constraints that are incorporated into the
network.
Form and function of negation in early developmental Cantonese
Authors: TAM CLARA W-Y. , STOKES STEPHANIE F.
Published: July 2002

This study investigated the interface of form and function in the
acquisition of negation in Cantonese-speaking children. The data, from
the Hong Kong Cantonese Child Language Corpus, were longitudinal
spontaneous samples of eight children aged 1;5 to 3;8. The main issues
of the study were the sequence of emergence of negative markers mou5,
m4 and mei6 and the acquisition trend of 11 semantic categories of
negation in children's expressive language. The acquisition trend of the
semantic categories matched Bloom's (1970, 1991a) finding that Non-existence
preceded Rejection and Denial.
Young children's understanding of the cognitive

verb forget
Authors: HILL ROSLYN , COLLIS GLYN M. , LEWIS VICKY A.
Published: July 2002

Investigation of children's understanding of the cognitive

verb forget has

shown that young children do not consider the role of prior knowledge

when using this verb. Thus, someone may be said to have forgotten a

fact despite not ever having previously known it. However, forget
can

also be used to refer to a failure to recall a prior intention. Three

experiments examined the role of prior intention as well as prior

knowledge in the comprehension of forget by 160 young children
aged

four to eight years. The results showed that children initially have two

interpretations of forget: as an unfulfilled desire

rather than a failure to

recall a prior intention, and as a state of not knowing rather than a failure

to recall prior knowledge. Explanations for the late comprehension of

forget are discussed in terms of representation of knowledge and

intention, processing capacity and exposure to pragmatic usages.
The Emergence of Nautical Astronomy in Portugal in the XVth century
Authors: Randles W. G. L.
Published: July 2002

Of the great oceans of the world, the Atlantic, because of its
violence, was the
last to be mastered by man. The task in its entirety had to wait for the
Portuguese
sailors of the Renaissance. Isidore of Seville (c. 570–636), a Christian
writer of
the late Roman Empire, had written of the Atlantic that it was ‘incommensurable

and uncrossable’. Although Pliny (a.d. 23–79) refers
vaguely to the Canary
Islands, all knowledge of them disappears in the Middle Ages until a Portuguese

expedition under the command of the Italian Lanzarotto Malocello ‘re-
discovered’ them in 1336. Italian charts of the XIVth century begin
progressively
to show the Canaries, Madeira, Porto Santo and the Azores, but all aligned
along
a N/S axis without any appreciation of the relative distances between
them or
how far they lay from the European shore. The first written evidence of
the
Portuguese ‘discovery’ of the islands of Madeira and Porto
Santo appears in
1419–20 and of the Azores in 1427, about the same time as they began
to be
colonised under the aegis of Prince Henry of Portugal, called the ‘Navigator’.

The difficulties of returning to them on regular voyages was to motivate
the
Portuguese to develop methods of measurement using the Pole Star as a
navigational aid and this led, not only to a greater accuracy in placing
the islands
on the charts, but also to a greater precision in the charting of the west
African
coastline which they were progressively exploring during the second half
of the
XVth century.

Claims that Portuguese nautical astronomy originated in Aragon and was

transmitted from there to Portugal or was introduced into Portugal from

Germany by Regiomontanus and Martin Behaim have long ago been shown to
be
baseless.
GPSIM: A Personal Computer-Based GPS Simulator System
Authors: Ibrahim D.
Published: July 2002

Global Positioning Systems (GPS) are now in use in many applications,
ranging from GIS
to route guidance, automatic vehicle location (AVL), air, land, and marine
navigation, and
many other transportation and geographical based applications. In many
applications, the
GPS receiver is connected to some form of intelligent electronic system
which receives the
positional data from the GPS unit and then performs the required operation.
When
developing and testing GPS-based systems, one of the problems is that it
is usually necessary
to create GPS-compatible geographical data to simulate a GPS operation
in real time. This
paper provides the details of a Personal Computer (PC)-based GPS simulator
system called
GPSIM. The system receives user way-points and routes from Windows-based
screen forms
and then simulates a GPS operation in real time by generating most of the
commonly used
GPS sentences. The user-specified waypoints are divided into a number of
small segments,
each segment specifying a small distance in the direction of the original
waypoint. The GPS
sentence corresponding to the geographical coordinates of each segment
is then sent out of
the PC serial port. The system described is an invaluable testing tool
for GPS-based system
developers and also for people training to learn to use GPS-based products.
The critical load concept for emission abatement strategies in Europe: a review
Authors: BASHKIN VLADIMIR N.
Published: July 2002

Critical loads studies (critical load is ‘a quantitative estimate of an exposure to one or more pollutants below which no harmful effects may occur’) have been used as the basis for assessing European strategies for reduction of sulphur emissions within the United Nations (UN) Economic Commission for Europe (ECE) Convention on Long-Range Transboundary Air Pollution (LRTAP). It is expected that the critical loads method will be applied to future international agreements under the Convention. Mapping of European critical loads conducted for the LRTAP Convention have progressed notably in recent years.

The concept of designing pollution control measures with the aim of protecting the most sensitive ecosystems, led to the creation of the Task Force on Mapping and Coordination Centre for Effects to implement these concepts on a European scale together with the corresponding National Focal Centres. The Russian National Focal Centre is used to illustrate how critical load data can be applied at the scale of a large country.

The policy implications resulting from the methods described in this review would support the development of an acidification protocol. While this has been suggested in the past, it is only now that scientific knowledge has advanced sufficiently to consider the feasibility of such a policy.
Interpreting puma (Puma concolor) population estimates for theory and management
Authors: SMALLWOOD K. SHAWN
Published: July 2002

Estimates of population size have been essential for ecological theory and wildlife management, but they depend on spatial scales of observation. Reported aspects of study and interpretive design were tested to see if they could explain variation in puma (Puma concolor) density. Comparison of puma studies revealed information shortfalls and possible confounding effects in research trends. Vegetation descriptions and other biological and physical aspects of the study site explained none of the 30-fold range of variation in puma density, nor did sampling and estimation methods and other aspects of study and interpretive design. Most (78%) of the variation in puma density estimates can be explained by the spatial extent of study area. Given the effect of scale, puma density estimates have been inappropriately extrapolated to larger geographic areas for management purposes. Due to spatial shifting of local population clusters, conventional density estimates cannot contribute to assessments of puma population trend without study at multiple sites over longer periods of time. Field studies would contribute more to knowledge of puma by spanning larger areas, a greater variety of land uses and habitats, and more of puma's range of distribution.
Improving efficiency of procedures for compositional synthesis
by using bidirectional search
Authors: CHAKRABARTI AMARESH
Published: July 2002

This article is an attempt to improve the efficiency
of procedures for compositional synthesis of design solutions
using building blocks. These procedures have found use
in a wide range of applications, and are one of the most
substantial outcomes of research into automated synthesis
of design solutions. Due to their combinatorial nature,
these procedures are highly inefficient in solving problems,
especially when the database of building blocks for synthesis
or the problem size is large. Previous literature often
focuses on improving only the algorithm part of a procedure,
although it is both its algorithm and database which together
determine the overall efficiency of the procedure. This
article reports the construction and analysis of an improved
algorithm, based on bidirectional search, for efficient
compositional synthesis of design solutions using a set
of building blocks.
Queuing network analysis for waterways with artificial neural
networks
Authors: ZHU LIANG , SCHONFELD PAUL , KIM YEON MYUNG , FLOOD IAN , TING CHING-JUNG
Published: July 2002

An Artificial Neural Network (ANN) model has been developed
for analyzing traffic in an inland waterway network. The
main purpose of this paper is to determine how well such a
relatively fast model for analyzing a queuing network could
substitute for far more expensive simulation. Its substitutability
for simulation is judged by relative discrepancies in
predicting tow delays between the ANN and simulation
models. This model is developed by integrating five distinct
ANN submodels that predict tow headway variances at (1)
merge points, (2) branching (i.e., diverging) points, (3)
lock exits, and (4) link outflow points (e.g., at ports,
junctions, or lock entrances), plus (5) tow queuing delays
at locks. Preliminary results are shown for those five
submodels and for the integrated network analysis model.
Eventually, such a network analyzer should be useful for
designing, selecting, sequencing, and scheduling lock improvement
projects, for controlling lock operations, for system maintenance
planning, and for other applications where many combinations
of network characteristics must be evaluated. More generally,
this method of decomposing complex queuing networks into
elements that can be analyzed with ANNs and then recombined
provides a promising approach for analyzing other queuing
networks (e.g., in transportation, communication, computing,
and production systems).
Determinants of case fatality rates of meningococcal disease during outbreaks in Makkah, Saudi Arabia, 1987–97
Authors: EL BUSHRA H. E. , HASSAN N. M. M. , AL-HAMDAN N. A. , AL-JEFFRI M. H. , TURKISTANI A. M. , AL-JUMAILY A. , ALI M. A. , RAHAMA A. M.
Published: July 2002

We studied case-fatality rates (CFRs) among cases of meningococcal disease (MCD) admitted
to Makkah (Saudi Arabia) hospitals during the period 1988–97. Of 483 cases, 431 (89·2%)
were due to strains of serogroup A, 31 (6·4%) to serogroup W135, 16 (3·3%) to serogroup C,
and 5 (1·0%) to serogroup B. Eighty-one patients died (case fatality rate (CFR)) 16·8%, 95%
CI 13·5%, 20·4%). The CFR in infections due to serogroup A strains was 14·8%, and for
other serogroups it was 32·7% (95% CI 20·3%, 47·1%). The CFR of MCD due to N.
meningitidis serogroup A increased steadily with age (P < 0·05). Seeking first medical help at a
foreign Hajj medical mission and being treated in a non-specialized hospital were associated
with a higher case fatality rate.
Selection of neutralizing antibody escape mutants with type A

influenza virus HA-specific polyclonal antisera: possible

significance for antigenic drift
Authors: CLEVELAND S. M. , TAYLOR H. P. , DIMMOCK N. J.
Published: July 2002

Ten antisera were produced in rabbits by two or three intravenous

injections of inactivated

whole influenza type A virions. All contained haemagglutination-inhibition
(HI)

antibody

directed predominantly to an epitope in antigenic site B and, in addition,

various amounts of

antibodies to an epitope in site A and in site D. The ability of untreated

antisera to select

neutralization escape mutants was investigated by incubating virus possessing

the homologous

haemagglutinin with antiserum adjusted to contain anti-B epitope HI titres
of

100, 1000 and

10000 HIU/ml. Virus-antiserum mixtures were inoculated into embryonated

hen's eggs, and

progeny virus examined without further selection. Forty percent of the
antisera

at a titre of

1000 HIU/ml selected neutralizing antibody escape mutants as defined
by

their lack of

reactivity to Mab HC10 (site B), and unchanged reactivity to other Mabs
to site

A and site D

epitopes. All escape mutant-selecting antisera had a ratio of anti-site
B

(HC10)-epitope

antibody[ratio ]other antibodies of [ges ]2·0[ratio ]1. The antiserum
with

the highest ratio (7·4[ratio ]1) selected

escape mutants in all eggs tested in four different experiments. No antiserum

used at a titre of

10000 HIU/ml allowed multiplication of any virus. All antisera used
at a

titre of 100 HIU/ml

permitted virus growth, but this was wild-type (wt) virus. We conclude
that a

predominant

epitope-specific antibody response, a titre of [ges ]1000 HIU/ml, and
a low

absolute titre of other

antibodies ([les ]500 HIU/ml) are three requirements for the selection
of

escape mutants. None of

the antisera in this study could have selected escape mutants without an

appropriate dilution

factor, so the occurrence of an escape mutant-selecting antiserum in nature

is likely to be a rare event.