bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of thermocapillary flows in non-cylindrical liquid bridges
Authors: NIENHÜSER CH. , KUHLMANN H. C.
Published: July 2002

The thermocapillary flow in liquid bridges is investigated numerically. In the limit
of large mean surface tension the free-surface shape is independent of the flow
and temperature fields and depends only on the volume of liquid and the hydrostatic
pressure difference. When gravity acts parallel to the axis of the liquid bridge the shape
is axisymmetric. A differential heating of the bounding circular disks then causes a
steady two-dimensional thermocapillary flow which is calculated by a finite-difference
method on body-fitted coordinates. The linear-stability problem for the basic flow is
solved using azimuthal normal modes computed with the same discretization method.
The dependence of the critical Reynolds number on the volume fraction, gravity level,
Prandtl number, and aspect ratio is explained by analysing the energy budgets of the
neutral modes. For small Prandtl numbers (Pr = 0.02) the critical Reynolds number
exhibits a smooth minimum near volume fractions which approximately correspond
to the volume of a cylindrical bridge. When the Prandtl number is large (Pr = 4)
the intersection of two neutral curves results in a sharp peak of the critical Reynolds
number. Since the instabilities for low and high Prandtl numbers are markedly
different, the influence of gravity leads to a distinctly different behaviour. While
the hydrostatic shape of the bridge is the most important effect of gravity on the
critical point for low-Prandtl-number flows, buoyancy is the dominating factor for
the stability of the flow in a gravity field when the Prandtl number is high.
The turbulent wake of two side-by-side circular cylinders
Authors: ZHOU Y. , ZHANG H. J. , YIU M. W.
Published: July 2002

This work is an experimental study of the turbulent vortex structures, and heat
and momentum transport in the wake of two side-by-side circular cylinders. The
spacing T between the cylinder axes was varied from 1.5d to 3d (d is the cylinder
diameter). Both cylinders were slightly heated. A movable three-wire probe measured
the velocity and temperature fluctuations, and an X-wire provided a phase reference.
Measurements were conducted at x/d = 10, 20 and 40 at a Reynolds number of
5800 (based on d and the free-stream velocity U∞). At T/d = 1.5, the phase-averaged
velocity and temperature fields display a single vortex street. The two rows of vortices
exhibit a significant difference in the maximum vorticity, size and lateral distance
from the flow centreline. As T/d is increased to 3.0, the flow is totally different. Two
antiphase streets occur initially. They are less stable, with vortices weakening faster,
than the street at T/d = 1.5. By x/d = 40, one street only is identifiable. Effective
vorticity flux density indicates that, while the outer vortex nearer to the free stream
interacts largely with the adjacent oppositely signed inner vortices located near the
flow centreline, the inner vortex interacts with the cross-stream inner vortices as well
as with adjacent outer vortices. As a result, vorticity associated with the inner vortex
is annihilated quicker than that associated with the outer vortex, leading to the early
disappearance of inner vortices and formation of a single street. The contribution of
the coherent motion of various Reynolds-averaged quantities such as the momentum
and heat fluxes has also been quantified and discussed in conjunction with the vortex
structures of the flow and temperature fields.
A low-dimensional model for simulating three-dimensional cylinder flow
Authors: MA XIA , KARNIADAKIS GEORGE EM
Published: July 2002

We investigate the stability and dynamics of three-dimensional limit-cycle states in
flow past a circular cylinder using low-dimensional modelling. High-resolution direct
numerical simulations are employed to obtain flow snapshots from which the most
energetic modes are extracted using proper orthogonal decomposition. We show that
the limit cycle is reproduced very accurately with only twenty three-dimensional
modes. The addition of two-dimensional modes to the Karhunen–Loeve expansion
basis improves the ability of the model to capture the three-dimensional bifurcation,
including the discontinuity in the Strouhal number discovered experimentally.
The effect of three-dimensional obstacles on
marginally separated laminar
boundary layer flows
Authors: BRAUN STEFAN , KLUWICK ALFRED
Published: July 2002

We consider the steady viscous/inviscid interaction of a two-dimensional, nearly
separated, boundary layer with an isolated three-dimensional surface-mounted obstacle,
for example in the large Reynolds number flow around the leading edge of a slender
airfoil at a small angle of attack. An integro-differential equation describing the
effect of the obstacle on the wall shear stress valid within the interaction regime is
derived and solved numerically by means of a spectral method, which is outlined
in detail. Typical solutions of this equation are presented for different values of the
spanwise width B of the obstacle including the limiting cases B → 0 and B → ∞.
Special emphasis is placed on the occurrence of non-uniqueness. On the main (upper)
solution branch the disturbances to the flow field caused by the obstacle decay in the
lateral direction. Conversely a periodic flow pattern, having no decay in the spanwise
direction, was found to form on the lower solution branch. These branches are
connected by a bifurcation point, which characterizes the maximum (critical) angle
of attack for which a solution of the strictly plane interaction problem exists. An
asymptotic investigation of the interaction equation, in the absence of any obstacle,
for small deviations of this critical angle clearly reflects the observed behaviour of the
numerical results corresponding to the different branches. As a result we can conclude
that the primarily local interaction process breaks down in a non-local manner even
in the limit of vanishing (three-dimensional local) disturbances of the flow field.
Surface folds during the penetration of a
viscoelastic fluid by a sphere
Authors: PODGORSKI THOMAS , BELMONTE ANDREW
Published: July 2002

When a sphere settles through the free surface of a viscous fluid, the interface is
deformed and assumes a funnel shape behind the sphere. If the fluid is viscoelastic and
the settling process is fast compared to the relaxation time of the fluid, elastic effects
are dominant and an instability occurs. The interface loses its original axisymmetry
and buckles, leading to a particular mode of pinch-off unseen in Newtonian fluids. We
present experimental evidence that stress boundary layers form in this type of flow,
and argue that a physical mechanism for this instability can be recovered, at least
qualitatively, by considering the stability of a stretched anisotropic elastic membrane
in a pressure field.
Upper bounds on general dissipation functionals
in turbulent shear flows: revisiting the
‘efficiency’ functional
Authors: KERSWELL R. R.
Published: July 2002

We show how the variational formulation introduced by Doering & Constantin to rigorously
bound the long-time-averaged total dissipation rate [ ] in turbulent shear flows
can be extended to treat other long-time-averaged functionals lim supT→∞(1/T)×∫0Tf(D, Dm, Dv)dt of the total dissipation D, dissipation in the mean field Dm and
dissipation in the fluctuation field Dv. Attention is focused upon the suite of functionals
f = D(Dv/Dm)n and f = Dm(Dv/Dm)n (n [ges ] 0) which include the ‘efficiency’
functional f = D(Dv/Dm) (Malkus & Smith 1989; Smith 1991) and the dissipation in
the mean flow f = Dm (Malkus 1996) as special cases. Complementary lower estimates
of the rigorous bounds are produced by generalizing Busse's multiple-boundary-layer
trial function technique to the appropriate Howard–Busse variational problems built
upon the usual assumption of statistical stationarity and constraints of total power
balance, mean momentum balance, incompressibility and boundary conditions. The
velocity field that optimizes the ‘efficiency’ functional is found not to capture the
asymptotic structure of the observed mean flow in either plane Couette flow or
plane Poiseuille flow. However, there is evidence to suppose that it is ‘close’ to a
neighbouring functional that may.
Exact results with the J-integral applied
to free-boundary flows
Authors: BEN AMAR MARTINE , RICE JAMES R.
Published: July 2002

We apply the J-integral to free-boundary flows in a channel geometry such as viscous
fingering or blob injection in Hele-Shaw cells, void propagation in electromigration,
and injection of air bubbles into inviscid liquids. The theory of that and related
conservation integrals, developed in elasticity, is outlined in a way that is applicable
to fluid mechanics problems. Depending on the boundary conditions, for infinite
bubbles in Laplacian fields we are able to use the J-integral to predict finger width if
such solutions exist or to predict that there are no solutions. For finite sized bubbles,
bounds can sometimes be derived. In the case of Hele-Shaw flows, in which solutions
appear as a continuum, finger width cannot be constrained, but we do obtain a new
derivation and generalization of Richardson moment conservation. Applications to
vortex motion are also outlined briefly.
The effect of compressibility on the critical swirl
of vortex flows in a pipe
Authors: RUSAK Z. , LEE J. H.
Published: July 2002

The effect of compressibility on the critical swirl level for breakdown of subsonic
vortex flows in a straight circular pipe of finite length is studied. This work extends
the critical-state concept of Benjamin (1962) to include the influence of Mach number
on the flow behaviour. The analysis is based on a linearized version of the equations
for the motion of a steady, axisymmetric, inviscid and compressible swirling flow of a
perfect gas. The relationship between the velocity, density, temperature and pressure
perturbations to a base columnar flow state are derived. An eigenvalue problem is
formulated to determine the first critical level of swirl at which a special mode of a
non-columnar small disturbance may appear on the base flow. It is found that when
the characteristic Mach number of the base flow tends to zero the eigenvalue problem
and the critical swirl are the same as defined by Wang & Rusak (1996a, 1997a) in their
study of incompressible swirling flows in pipes. As the characteristic Mach number
is increased, the critical swirl level increases and the flow perturbation expands in
the radial direction. As the Mach number is increased toward a certain limit value
related to the core size of the vortex, the critical swirl reaches very large values and
becomes singular. The present results indicate that the axisymmetric breakdown of
high-Reynolds-number compressible vortex flows may be delayed with the increase
of the flow Mach number.
Nonlinear Smoluchowski slip velocity and
micro-vortex generation
Authors: BEN Y. , CHANG H.-C.
Published: July 2002

When an electric field is applied across a conducting and ion-selective porous granule
in an electrolyte solution, a polarized surface layer with excess counter-ions is created.
The depth of this layer and the overpotential V across this layer are functions of
the normal electric field j on the granule surface. By transforming the ionic flux
equations and the Poisson equation into the Painlevé equation of the second type
and by analysing the latter's asymptotic solutions, we derive a linear universal j–V
correlation at large flux with an electrokinetic slip length β. The flux-induced surface
polarization produces a nonlinear Smoluchowski slip velocity that can couple with
the granule curvature to produce micro-vortices in micro-devices. Such vortices are
impossible in irrotational electrokinetic flow with a constant zeta-potential and a
linear slip velocity.
Orientation phenomena for electron–ion
collisional excitations in a classical nonideal
plasma
Authors: JUNG YOUNG-DAE
Published: July 2002

Orientation phenomena for direct 1s → 2p±1 excitations in electron–hydrogenic-ion collisions are investigated in a classical nonideal plasma. An effective
pseudopotential model taking into account plasma-screening and collective effects
is applied to describe the interaction potential in a nonideal plasma. The orientation
parameter for direct 1s → 2p±1 excitations in a nonideal plasma is obtained as
a function of the impact parameter, the nonideal-plasma parameter, the Debye
length, and the projectile energy. The result shows that the nonideal effect reduces
the propensity of the 1s → 2p−1
transition. It is also found that the nonideal effect
on the orientation parameter increases with increasing projectile energy.
Japan's emblematic English
Authors: Hyde Barbara
Published: July 2002

An analysis of ‘public English’ and (not) learning the language in Japan.

Visitors to Japan, whether linguists or laymen, frequently come back with their own collection of quaint uses of English, gathered from public signs, advertising and so on, which vary from the odd to the simply incorrect. This may provide complacent amusement for the native speaker, but is not surprising or unique: Budapest airport until relatively recently sported a large sign reading Welcome in Hungary. What is especially interesting in Japan is not the mistakes but the puzzling function of many such signs. English words and messages are often combined with Japanese, so that, as a non-Japanese speaker, your eye is at first attracted then baffled, until you realise that the English is not aimed at you, a native speaker, but at native speakers of Japanese. But who among the Japanese is it aimed at, and why?
Accommodating Estuary English
Authors: Levey David , Harris Tony
Published: July 2002

A study in accentual compromise.

There is something in the very name Estuary English which fills certain sectors of British society with horror and fear, as if we were in the presence of a contagious and potentially devastating disease. It can provoke what John Maidment (1994:7) termed the ‘Disgusted-of-Tunbridge-Wells Syndrome’ (DTWS):

“Nothing is likely to enrage DTW more than the suggestion that the standard language which he/she holds so dear, the grail of which he/she sees him/herself the guardian, is usurped by the usage of people who are NOT OUR CLASS. DTW is not going down without a fight, you may be sure.”

This Times-reading, Radio 4-listening guardian of the English language, armed with pen and paper, is ready to pick up on mispronunciations, misspellings, and misusages of grammar and send in a letter of complaint, bemoaning the decline of the language.
Wakimoto modules for the affine Lie superalgebras
A(m−1, n−1)(1) and D(2, 1, a)(1)
Authors: IOHARA KENJI , KOGA YOSHIYUKI
Published: July 2002

In this paper, we construct Wakimoto modules for basic affine Lie superalgebras of
type A(m−1, n−1)(1) and D(2, 1, a)(1). As an application, we compute the characters
of irreducible highest weight modules at the critical level.
An Intelligent Navigation Solution for Land Mobile Location-Based Services
Authors: Scott-Young Stephen , Kealy Allison
Published: July 2002

The increasing availability of small, low-cost GPS receivers has established a firm growth in the production of Location-Based Services (LBS). LBS, such as in-car navigation systems, are not necessarily reliant on high accuracy but a continuous positioning service. When available, the accuracy provided by the standard positioning service (SPS) of 30 metres, 95% of the time is often acceptable. The reality is, however, that GPS does not work in all situations, and it is therefore common to integrate GPS with additional sensors. The use of low-cost inertial sensors alone during GPS signal outage is severely restricted due to the accumulation of errors that is inherent with such dead reckoning (DR) systems. Through the integration of spatial information with real-time positioning sensors, intelligence can be added to the land mobile navigation solution. The information contained within a Geographical Information System (GIS) provides additional observations that can be used to improve the navigation result. With this approach, the solution is not dependent on the performance capabilities of the navigation sensors alone. This enables the use of lower accuracy navigation devices, allowing low-cost systems to provide a sustained, viable navigation solution despite long-term GPS outages. Practical results are presented comparing solutions obtained from a hand-held GPS receiver to a gyroscope and odometer.
Sexual dimorphism and facial growth in papionin monkeys
Authors: O'Higgins Paul , Collard Mark
Published: July 2002

Sexual dimorphism in the primate face has been studied intensively lately, but a number of issues remain controversial. For example, some studies have indicated that facial sexual dimorphism arises through ontogenetic scaling, whereas others have found it to be a consequence of both ontogenetic scaling and divergence in male and female growth trajectories. To shed further light on primate facial sexual dimorphism, geometric morphometric methods were applied to crania representing five papionin genera:Cercocebus,Lophocebus,Macaca,MandrillusandPapio. A first set of analyses focused on the pattern and degree of facial sexual dimorphism exhibited by adult specimens. A second set of analyses concentrated on the ontogeny of facial sexual dimorphism in infant‐to‐adult age series. The first set indicated that the five genera exhibit significant facial sexual dimorphism. These analyses also revealed that the genera share several features of sexual dimorphism. Males are distinguished from females in having a more prognathic mid‐face, a relatively more inferiorly and anteriorly positioned prosthion, relatively increased subnasal height and relatively broader zygomatic roots. They are also differentiated from females in their maxillae, which relative to the zygomatics are narrow but vertically deep, especially in the posterior aspect. Also, the first set of analyses indicated thatMacacais the most distinctive of the genera in terms of sexual dimorphism. The distinctive features of theMacacasexual dimorphism are that males exhibit relatively wider nasal apertures and premaxillae than females, together with a relative increase in breadth across the inferior zygomatic roots. The second set of analyses demonstrated that in all the genera, sexual dimorphism arises partly through ontogenetic scaling and partly through a late divergence in male and female growth trajectories. The analyses also indicated that the relative contribution of these processes to sexual dimorphism varies among the genera. Ontogenetic scaling is by far the most important process inLophocebusandPapio. Late divergence between male and female growth trajectories contributes proportionately more inCercocebusandMandrillus, although ontogenetic scaling still plays the major role. The relative contribution of late divergence between male and female growth trajectories is greatest inMacaca, in which it accounts for about half of the facial differences between adult males and females. In all five genera, ontogenetic scaling results in increased prognathism and greater relative maxillary size in males compared to females, whilst the late divergence involves the male mid‐face becoming proportionately larger and deeper than the female mid‐face, and the male posterior maxilla coming to lie more inferiorly with respect to the zygomatic root than its female counterpart.
Influence of flow regime on habitat selection by tadpoles in an Australian rainforest stream
Authors: Richards Stephen J.
Published: July 2002

This study examined how spatial variation in flow regime affects patterns of tadpole distribution in Birthday Creek, an upland rainforest stream in northern Queensland. Tadpoles of Litoria genimaculata and Mixophyes schevilli are restricted to habitats with little or no water flow, and L. nannotis and Nyctimystes dayi occur only in rapidly flowing and turbulent riffle habitats. The abilities of L. genimaculata, M. schevilli and L. nannotis to resist flow rates typical of riffle habitats were compared in a laboratory flow chamber and in an artificial riffle in the field. In the flow chamber, large tadpoles of L. genimaculata were more resistant to flow rates of 25 cm/s than were smaller individuals, but at 50 cm/s all tadpoles were dislodged irrespective of size. Large M. schevilli tadpoles were significantly more resistant than were smaller individuals only at the fastest flow rate. Large (> 25 mm body length) M. schevilli were resistant to the highest tested flow rates (50 cm/s), but in an artificial riffle with turbulence typical of a riffle both Litoria genimaculata and Mixophyes schevilli were rapidly dislodged irrespective of their size. Fast water speeds had little impact on L. nannotis in the flow chamber or in the artificial riffle. Litoria nannotis and other tadpoles living in riffles have evolved a range of morphological and behavioural traits that minimize exposure to, and maximize resistance to, fast‐flowing turbulent water within these habitats. The results of this study indicate that L. genimaculata and M. schevilli cannot live in riffles because they are unable to withstand the flow rates typical of these habitats.
From al-Kindī to al-Fārābī: Avicenna's Progressive Knowledge of Aristotle's Metaphysics according to his Autobiography
Authors: Bertolacci Amos
Published: July 2002

The autobiography witnesses a significant evolution in Avicenna's approach to Aristotle's Metaphysics during the years of his education. It clearly shows that, at a certain point of his philosophical training, Avicenna faced the entire text of the Metaphysics, was puzzled by its extent and complexity, and found in a treatise by al-Fārābī a guide for its understanding. But, albeit less perspicuously, the autobiography also suggests that this was not Avicenna's first encounter with the Metaphysics. Avicenna dealt with Aristotle's work in a previous stage of his studies as well. Then, however, he did not read the Metaphysics in its entirety, but, rather, focused only on its essential parts and some commentaries thereupon. The parts of the Metaphysics that Avicenna read in this earlier stage were books Alpha Elatton and Lambda, as constituting the natural theology of Aristotle's work. He neglected, on the contrary, the books corresponding to its ontological part. The special attention to Alpha Elatton and Lambda and the close connection between these two books in a theological context were peculiar traits of al-Kindī's approach to Aristotle's Metaphysics. Therefore, the evolving approach to Aristotle's Metaphysics that Avicenna's autobiography witnesses can properly be described as a passage from the Kindian to the Farabian way of interpretation.
Learning e-learning – a comprehensive investigation of course
developers’ and language teacher trainees’ views regarding the usefulness
and effectiveness of a multimedia self-tuition course
Authors: SERCU LIES , PETERS ELKE
Published: July 2002

The paper presents the results of a comparative investigation of course
developers’ and teacher trainees’ views regarding the usefulness and effectiveness
of a multimedia self-tuition course designed to introduce foreign language teacher trainees to
tools and methods for organising computer-assisted language learning. The paper first provides
a brief description of the home-study course itself. It describes the course’s main
components, its content as well as the learning and evaluation tasks the course provides in
support of the learning process. Next, the paper reports on the way in which the evaluation
project investigating teacher trainees’ and course developers’ views regarding the
effectiveness of the course was set up. The project’s design is presented, and the way
in which various procedures of data collection (written evaluations and individual interviews)
were triangulated is commented on. In the third section we present the investigation’s main
findings. The section focuses on points of agreement and disagreement between developers’
and trainees’ views regarding the usefulness and effectiveness of the course. Finally,
we describe the changes brought about by the evaluation project, and reflect on the necessity
to take account of future users’ views and requirements in the design and development
process if the training of foreign language teachers is to benefit from web-based delivery.
Bromeliaceae: Profile of an Adaptive Radiation. D. H. Benzing. Cambridge University Press. 2000. 690pp. ISBN 0 521 43031 3. £80.00 (hardback). DOI: 10.10M/S0960428602240159
Authors: HERBERT J.
Published: July 2002

..
Comment on Corner: Giolitti's Italy – Sonderweg or Well-Travelled Road?
Authors: De Grand Alexander
Published: July 2002

The idea of an Italian Sonderweg is interesting, but it is not exactly a new interpretation of the Giolittian era. Gaetano Salvemini was very clear in blaming Giolitti for distorting Italy's path to democracy. I agree with Paul Corner's cautionary remark that nothing before the First World War made fascism inevitable. Still, we should look closely at the fifteen years before the Great War, if for no other reason than the fact that the great hopes for reform that marked the period gave rise to little structural reform. Giolitti simply did not bring about the modernisation of the liberal parliamentary system. However, I have my doubts that this adds up to a Sonderweg. Nowhere on the Continent did a modern mass party of the bourgeoisie emerge before 1914. Moreover, in no country did the middle-class movement for reform develop solid links with the growing socialist movement. It is curious in this regard that Corner never mentions France. Certainly the Giolittian era resembles the post-Dreyfus period in French politics more than anything that happened in Germany. It would be interesting for Professor Corner to expand on the viability of the British Lib–Lab pact of 1906; it is implied that this was a model that worked elsewhere on the Continent (p. 286). I also find it surprising that he finds the roots of the Weimar coalition in prewar imperial Germany (p. 294).
Splitting methods
Authors: McLachlan Robert I. , Quispel G. Reinout W.
Published: July 2002

I thought that instead of the great number of precepts of which logic is composed,
I would have enough with the four following ones, provided that I made
a firm and unalterable resolution not to violate them even in a single instance.
The first rule was never to accept anything as true unless I recognized it to
be certainly and evidently such …. The second was to divide each of the difficulties
which I encountered into as many parts as possible, and as might be
required for an easier solution. (Descartes)

We survey splitting methods for the numerical integration of ordinary differential
equations (ODEs). Splitting methods arise when a vector field can be
split into a sum of two or more parts that are each simpler to integrate than
the original (in a sense to be made precise). One of the main applications of
splitting methods is in geometric integration, that is, the integration of vector
fields that possess a certain geometric property (e.g., being Hamiltonian, or
divergence-free, or possessing a symmetry or first integral) that one wants
to preserve. We first survey the classification of geometric properties of dynamical
systems, before considering the theory and applications of splitting
in each case. Once a splitting is constructed, the pieces are composed to form
the integrator; we discuss the theory of such ‘composition methods’ and summarize
the best currently known methods. Finally, we survey applications
from celestial mechanics, quantum mechanics, accelerator physics, molecular
dynamics, and fluid dynamics, and examples from dynamical systems, biology
and reaction–diffusion systems.
Development of porcine embryos produced by IVM/IVF in a medium with or without protein supplementation: effects of extracellular glutathione
Authors: Wang Wei-Hua , Day Billy N.
Published: July 2002

This study was designed to examine the effects of extracellular reduced glutathione on development of pig embryos, produced by in vitro maturation (IVM) and in vitro fertilisation (IVF), in a chemically defined North Carolina State University (NCSU) 23 medium or in NCSU 23 medium with bovine serum albumin (BSA). Microfilament distribution, as a marker of embryo quality, was also examined by immunocytochemical staining and confocal microscopy. When the inseminated oocytes were cultured in the defined medium containing 0-0.5 mM glutathione, blastocyst formation as observed only in the media with glutathione (8.5-16.0%). Increased numbers of blastomeres were observed in the blastocysts as the concentration of glutathione was increased (18.8±7.2 to 31.0±8.6). In NCSU 23 medium with 4 mg BSA/ml, addition of glutathione at concentrations of 0.125-0.5 mM significantly increased the proportions of oocytes that developed to blastocysts (39.2-52.5%) compared with the control (29.5%). However, no difference was observed in the average cell number in the blastocysts (41.9±15.6 to 49.1±15.5). There were no significant differences in the microfilament distribution in the embryos produced in the defined medium and in the BSA-containing medium. These results indicate that pig embryos produced by IVM/IVF can develop to the blastocyst stage in a defined medium. BSA and glutathione have a synergistic effect on pig embryo development.
The formation and evolution of the Solar System
Authors: ENCRENAZ THÉRÈSE
Published: July 2002

Astronomers have built the main components of a scenario for the formation of the Solar System. Small planetary bodies accreted others by collisions within a rotating protoplanetary disk that formed at the same time as the Sun. While terrestrial planets near the warming Sun could accumulate only solid metallic and silicate material, the giant planets formed from ice and gas at lower temperatures. Each planet and satellite then followed its own specific evolution, depending upon the properties of its atmosphere and/or surface. Information about the origin and evolution of the Solar System is also provided by the comets, which can be considered as frozen fossils of the Solar System's early stages. On the borders of the outer Solar System, beyond the orbit of Neptune, the newly discovered Edgeworth–Kuiper belt is probably the reservoir where short-period comets are formed.
Meteorological factors influencing the occurrence of air pollution episodes involving chimney plumes
Authors: Fisher Bernard
Published: July 2002

This paper is concerned with meteorological processes that may have an influence on the occurrence of episodes of high pollution involving chimney plumes. It reviews meteorological mechanisms that could lead to or maintain high concentrations at distances beyond the range normally considered in dispersion models (distances greater than 30 km). Fundamental parameters of the atmospheric boundary layer are shown to largely determine short‐range and long‐range dispersion, but their values are usually not well known in specific cases. A simple estimate is provided of the magnitude of the maximum hourly average concentrations during a long‐range fumigation episode from a tall stack. Copyright © 2002 Royal Meteorological Society
Turbulent kinetic energy in the atmospheric surface layer during the summer monsoon
Authors: Srivastava Manoj K , Sarthi P Parth
Published: July 2002

The turbulent kinetic energy (TKE) in the atmospheric surface layer (ASL) gives a measure of the intensity of turbulence that could be altered or brought about by mechanical generation, by thermal generation, through vertical transport into or away, and through dissipation. TKE is mainly responsible for the transportation of pollutants suspended in the air. In this paper, TKE evolution in the ASL is studied for Kharagpur (22.20° N, 87.18° E) during the summer monsoon by making use of data from a 30 m micrometeorological tower set up as part of the Monsoon Trough Boundary Layer Experiment (MONTBLEX). Under steady state and homogeneous conditions the various terms in the TKE equation are studied for active and non‐active phases of the monsoon in 1990. Their day‐to‐day variations and the budgets are studied at the 8 m and 15 m levels. The study reveals strong day‐to‐day variation and significant vertical variations within the ASL. Despite being a tropical station, the buoyancy term is much less than the contribution by mechanical generation ostensibly due to the monsoon. There are also differences between active and non‐active phases of the monsoon. Mechanical generation by wind shear has been found to be the dominating production term, while dissipation dominates the magnitude of all other terms. Copyright © 2002 Royal Meteorological Society
An LVQ connectionist solution to the non-determinacy problem in Arabic morphological analysis: a learning hybrid algorithm
Authors: EL-AFFENDI M. A.
Published: July 2002

Most of the morphological properties of derivational Arabic words are encapsulated in their
corresponding morphological patterns. The morphological pattern is a template that shows
how the word should be decomposed into its constituent morphemes (prefix + stem + suffix),
and at the same time, marks the positions of the radicals comprising the root of
the word. The number of morphological patterns in Arabic is finite and is well below 1000.
Due to these properties, most of the current analysis algorithms concentrate on discovering
the morphological pattern of the input word as a major step in recognizing the type and
category of the word. Unfortunately, this process is non-determinitic in the sense that the
underlying search process may sometimes associate more than one morphological pattern
with the given word, all of them satisfying the major lexical constraints. One solution to this
problem is to use a collection of connectionist pattern associaters that uniquely associate
each word with its corresponding morphological pattern. This paper describes an LVQ-based
learning pattern association system that uniquely maps a given Arabic word to its
corresponding morphological pattern, and therefore deduces its morphological properties.
The system consists of a collection of hetroassociative models that are trained using the
LVQ algorithm plus a collection of autoassociative models that have been trained using
backpropagation. Experimental results have shown that the system is fairly accurate and very
easy to train. The LVQ algorithm has been chosen because it is very easy to train and the
implied training time is very small compared to that of backpropagation.
The environmental Kuznets curve and satiation: a simple static model
Authors: Lieb Christoph M.
Published: July 2002

The environmental Kuznets curve (EKC) is a hypothesis stating that pollution rises with income at low income levels but falls at higher ones. We analyse the EKC in a representative consumer model in which pollution is generated by consumption and can be abated. We show that at low income levels no abatement is optimal and pollution increases with income. Once abatement expenditures are positive, we demonstrate that satiation in consumption is not only sufficient to find an EKC, but a tendency to satiation—or in other words the condition that environmental quality is a normal good—is even necessary if we assume a standard functional form for the pollution function. Finally, we reconsider the results of two related models of the literature: We verify that the relationship between the income elasticity of demand for environmental quality and the EKC is ambiguous.

(JEL: D62, O40, Q20)
Investing in soils: field bunds and microcatchments in Burkina Faso
Authors: Kazianga Harounan , Masters William A.
Published: July 2002

This research uses field-level data from Burkina Faso to ask what determines farmers' investment in two well-known soil and water conservation techniques: field bunds (barriers to soil and water runoff), and microcatchments (small holes in which seeds and fertilizers are placed). Survey data for 1993 and 1994 are used to estimate Tobit functions, compute elasticities of adoption and intensity of use, perform robustness tests and estimate alternative models. Controlling for land and labor abundance and other factors we find that those who have more ownership rights over farmland, and who do more controlled feeding of livestock, tend to invest more in both technologies. The result suggests that responding to land scarcity with clearer property rights over cropland and pasture could help promote investment in soil conservation, and raise the productivity of factors applied to land.
Theory and practice
Authors: THE EDITORS
Published: July 2002

Theory is usually assumed to precede practice but ‘Practice preceding theory’ is the
telling sub-title to Patrick Hodgkinson's essay on Leslie Martin on p. 297 of this issue.
It is a full year since we published an extended celebration of Martin's work together
with his essay ‘The grid as generator’ (arq 4/4). Kenneth Frampton's subsequent
Postscript (arq 5/1) placed Martin in a historical perspective. Spurred by Frampton's
assessment, Hodgkinson now reminds us how Martin's later theoretical work can be
said to have had its origins in the studio's early work.

This thought-provoking reminder comes at a time when, in the UK, architecture's
standing as a research-led university discipline remains as low as ever. Once again in
the government's recent Research Assessment Exercise no architecture school
achieved the highest rating. This was unremarked upon both by the professional
press (which was much more interested in the upsets at the top end of the league-table)
and by the RIBA (which probably hasn't even noticed and has certainly never
grasped the significance of university research). It seems that neither much of the
‘theory’ which so many architecture academics expound nor the odd bit of practice
that they manage to undertake is highly rated by the assessors.

This, of course, is not the outcome intended by the 1958 Oxford Conference on
Architectural Education (master-minded by Martin) which determined that in future
all architects should be educated within the research-led university system. But does
the RAE debacle matter? It certainly does. Research-rich schools are better resourced
— and that benefits both teaching and practice. We need to take a hard look at why
architecture fares so badly — and to question its grouping with construction
management and surveying. We must also consider the very nature of university-based
architectural research. Hodgkinson is right when he concludes, ‘much
thought still needs to be given to architectural theory if it is to raise itself from being
purely academic — and therefore practically useful.’

But take a look, too, at the articles on pp. 305 and 312 of this issue. The first, by
occasional practitioner and academic Peter Blundell Jones, sets out the case for
‘Working with the given’. In the second, ‘New meanings from old buildings’, Blundell
Jones and another practitioner/academic, John Sergeant, appraise three very modest
house conversions and extensions designed by them and by David Lea. These
architects have evolved their position over many years — developing, through
building, discussion and writing, a genuinely sustainable approach to the use of
resources. Their buildings may be modest but, together with their writing, they
eloquently encapsulate an approach or theory that is increasingly relevant — and
utterly practical.
Classical and non-classical computation
Authors: Knight Terry , Stiny George
Published: July 2002

Computers have come to play an important role in architectural
practice. Nonetheless, the promise of computation as a creative
partner in practice, and a means to better understand and support
the design process has yet to be realized. This article considers
aspects of computation, and alternative ways that these have been
approached in order to make computation useful in architecture
and other areas of spatial design.
Less than interesting
Authors: Mallinson Helen
Published: July 2002

Does Giles Oliver (letters, arq 5/3)
mean to connect the success of the
Tate Modern in ‘sucking in huge
crowds’ with the success of
architectural education? Both in
his view seem suspect
achievements. The Tate is not
proper architecture — it is too
brutish and poorly lit — while
current architectural education
avoids all that is proper to
architecture. His message is that
both public and consumer opinion
counteth for nought in these
matters. But what else have
professionals ever said?
Particularly the generations
brought up to believe that
unpopularity was architecture's
native condition. Frankly I am
rather encouraged by the
popularity of supposedly arcane
subjects like modern art, modern
architecture and architectural
education. At least we seem to be
getting one thing right. Not that I
am advocating complacency.
Keeping anything alive in our
management sodden culture is
tricky, particularly the kind of
creative team spirit required to
make projects work.
The architect and the academy
Authors: Murray Gordon C.
Published: July 2002

David Porter's letter in arq 5/1 was
timely. In recognizing the benefits
to be gained from the ‘two-way
street’ that connects architectural
education and practice, Porter
follows on from Robin Webster's
plea in arq 4/2 for ‘ordinary’
practitioners to teach ‘a high
standard of ordinariness’. Webster's
letter was provoked by Dean
Hawkes' paper, ‘The architect and
the academy’ (arq 4/1), in which he
quoted Kahn, Zumthor and Scarpa
on education, all regarding
teaching as a process of (self)
discovery.
Publication bias in ecology and evolution: an empirical assessment using the ‘trim and fill’ method
Authors: JENNIONS MICHAEL D. , MØLLER ANDERS P.
Published: July 2002

Recent reviews of specific topics, such as the relationship between male attractiveness to females and fluctuating asymmetry or attractiveness and the expression of secondary sexual characters, suggest that publication bias might be a problem in ecology and evolution. In these cases, there is a significant negative correlation between the sample size of published studies and the magnitude or strength of the research findings (formally the ‘effect size’). If all studies that are conducted are equally likely to be published, irrespective of their findings, there should not be a directional relationship between effect size and sample size; only a decrease in the variance in effect size as sample size increases due to a reduction in sampling error. One interpretation of these reports of negative correlations is that studies with small sample sizes and weaker findings (smaller effect sizes) are less likely to be published. If the biological literature is systematically biased this could undermine the attempts of reviewers to summarise actual biology relationships by inflating estimates of average effect sizes. But how common is this problem? And does it really effect the general conclusions of literature reviews? Here, we examine data sets of effect sizes extracted from 40 peer‐reviewed, published meta‐analyses. We estimate how many studies are missing using the newly developed ‘trim and fill’ method. This method uses asymmetry in plots of effect size against sample size (‘funnel plots’) to detect ‘missing’ studies. For random‐effect models of meta‐analysis 38% (15/40) of data sets had a significant number of ‘missing’ studies. After correcting for potential publication bias, 21% (8/38) of weighted mean effects were no longer significantly greater than zero, and 15% (5/34) were no longer statistically robust when we used random‐effects models in a weighted meta‐analysis. The mean correlation between sample size and the magnitude of standardised effect size was also significantly negative (rs=‐0.20, P < 0‐0001). Individual correlations were significantly negative (P < 0.10) in 35% (14/40) of cases. Publication bias may therefore effect the main conclusions of at least 15–21% of meta‐analyses. We suggest that future literature reviews assess the robustness of their main conclusions by correcting for potential publication bias using the ‘trim and fill’ method.
New mutations in the CBFA1 gene in two Mexican patients with cleidocranial dysplasia
Authors: Machuca‐Tzili L , Monroy‐Jaramillo N , González‐del Angel A , Kofman‐Alfaro S
Published: July 2002

Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal disorder exhibiting a wide clinical spectrum ranging from minimal anomalies to classic CCD. Mutations scattered throughout the entire CBFA1 gene have been related to this disorder. However, it seems that most of them affect the highly conserved Runt domain, abolishing the DNA‐binding ability of this transcription factor. Moreover, no systematic effect has been found to relate the type of mutation to the severity of the clinical features. In this paper, we studied two unrelated patients with classic CCD. DNA analysis revealed two novel mutations and three undescribed polymorphisms. One of the substitutions was a missense mutation in the Q/A domain leading to the replacement of a polar residue by a nonpolar one (158 A → T [Q53L]). The second was an uncommon heterozygous stop codon mutation (1565 G → C [X522S]) which theoretically results in a longer protein with 23 additional amino acids. This is the first report of this type of mutation in CBFA1. We discuss the possible consequences of these mutant sequences, although no phenotype–genotype correlation could be established. Our findings expand the existing number of allelic variants in this pathology.
Recurrent 22q11.2 deletion in a sibship suggestive of parental germline mosaicism in velocardiofacial syndrome
Authors: Sandrin‐Garcia P , Macedo C , Martelli LR , Ramos ES , Guion‐Almeida ML , Richieri‐Costa A , Passos GAS
Published: July 2002

Deletions of chromosome 22q11.2 are recognized as the main cause of a number of clinical phenotypes, including velocardiofacial syndrome (VCFS) and DiGeorge syndrome (DGS). Velocardiofacial syndrome is a relatively common developmental disorder that is characterized by craniofacial anomalies and conotruncal heart defects. Most 22q11.2 deletions occur sporadically, although the deletion may be transmitted in some cases. The present performed a molecular analysis in one family including a patient with clinical diagnosis of VCFS and his sister with a suggestive phenotype. Six polymorphic 22q11.2 markers (i.e. D22S420, D22S264, D22S941, D22S306, D22S425 and D22S257) were used for genotype analysis of the DNA from the patients and unaffected relatives. The results revealed a 22q11.2 deletion in the patient and his sister from one of six markers (i.e. D22S941). Genotype analysis demonstrated that the deletion in this sib was of maternal origin. The results suggest that the mother probably has gonadal mosaicism. The other relatives present normal DNA profiles for all markers. These results have implications for genetic counseling because of a risk of transmission by germ cells carrying the deletion, even when parents present with a normal DNA profile in their blood cells.