bluuebunny/crossref_metadata_2025 huggingface dataset:
Mammary apoptosis and lactation persistency in dairy animals
Authors: STEFANON BRUNO , COLITTI MONICA , GABAI GIANFRANCO , KNIGHT CHRISTOPHER H. , WILDE COLIN J.
Published: July 2002

The decline in milk yield after peak lactation in dairy animals has long been a biological conundrum for the mammary biologist, as well as a cause of considerable lost income for the dairy farmer. Recent advances in understanding the control of the mammary cell population now offer new insights on the former, and a potential means of alleviating the latter. The weight of evidence now indicates that a change in mammary cell number, the result of an imbalance between cell proliferation and cell removal, is a principal cause of declining production. Further, it suggests that the persistency of lactation, the rate of decline in milk yield with stage of lactation, is strongly influenced by the rate of cell death by apoptosis in the lactating gland. Mammary apoptosis was first demonstrated during tissue involution after lactation, but has now been detected during lactation, in mammary tissue of lactating mice, goats and cattle. Those factors that determine the rate of cell death by apoptosis are as yet poorly characterized, but include the frequency of milking in lactating goats. Initial evidence suggests that nutrition also is likely to influence cell survival after peak lactation, an important factor being the degree of oxidative stress imposed by feed and the tissue's ability to deal with, and prevent damage by, reactive oxygen species. Comparison of cows in calf or not pregnant during declining lactation also indicates a likely influence of reproductive hormones, with oestradiol and progesterone acting to preserve mammary ductal and alveolar integrity during the dry period, while allowing a degree of apoptosis and cell replacement. In each case, the molecular mechanisms controlling mammary cell survival (or otherwise) are as yet poorly defined. On the other hand, more persistent lactations are likely to benefit animal welfare through fewer calvings and by placing less emphasis on maximal production at peak lactation, and modelling of persistent lactation with longer calving intervals indicates their likely economic benefits. In these circumstances, there is considerable incentive to elucidate the determinants of mammary apoptosis, and the factors controlling the dynamic balance between cell proliferation and cell death in the lactating mammary gland.
Development and validation of a nephelometric immunoassay for IgG1 in milk
Authors: COLLIN ROGER , PROSSER COLIN , MCLAREN ROB , THOMSON MARY , MALCOLM DAVID
Published: July 2002

A nephelometric immunoassay, with a detection range of 0·3 to 5 g IgG1/l, was developed for the determination of immunoglobulin in bovine milk. The assay exhibited no significant cross-reactivity with αS1-casein, αS2-casein, β-casein, κ-casein or β-lactoglobulin and 39% cross-reactivity with IgG2. The nephelometric assay was compared with ELISA and RID (24 h and 48 h incubations) assays using 105 duplicate milk samples covering IgG1 values ranging from 0·45 to 1·8 g1. The results obtained from all assays showed good agreement with the exception of those obtained by the RID assay (24 h incubation) which gave lower results in samples containing more than 1·2 g IgG1/l. It was concluded that the nephelometric assay is a reliable, rapid and convenient method suitable for the quantification of IgG1 in milk. The assay can be configured for routine high-throughput milk quality assurance for IgG1 in dairy laboratories.
Turbulent rotating convection: an experimental study
Authors: VOROBIEFF PETER , ECKE ROBERT E.
Published: July 2002

We present experimental measurements of velocity and temperature fields in horizontal
planes crossing a cylindrical Rayleigh–Bénard convection cell in steady rotation
about its vertical axis. The range of dimensionless rotation rates Ω is from zero to
5×104 for a Rayleigh number R = 3.2×108. The corresponding range of convective
Rossby numbers is ∞ > Ro > 0.06. The patterns of velocity and temperature and the
flow statistics characterize three basic flow regimes. For Ro [Gt ] 1, the flow is dominated
by vortex sheets (plumes) typical of turbulent convection without rotation. The flow
patterns for Ro ∼ 1 are cyclone-dominated, with anticyclonic vortices rare. As the
Rossby number continues to decrease, the number of anticyclonic vortex structures
begins to grow but the vorticity PDF in the vicinity of the top boundary layer still
shows skewness favouring cyclonic vorticity. Velocity-averaging near the top of the
cell suggests the existence of a global circulation pattern for Ro [Gt ] 1.
Effect of constitutive laws for two-dimensional
membranes on flow-induced capsule deformation
Authors: BARTHÈS-BIESEL DOMINIQUE , DIAZ ANNA , DHENIN EMMANUELLE
Published: July 2002

Three constitutive laws (Skalak et al.'s law extended to area-compressible interfaces,
Hooke's law and the Mooney–Rivlin law) commonly used to describe the mechanics
of thin membranes are presented and compared. A small-deformation analysis of
the tension–deformation relation for uniaxial extension and for isotropic dilatation
allows us to establish a correspondence between the individual material parameters
of the laws. A large-deformation analysis indicates that the Mooney–Rivlin law is
strain softening, whereas the Skalak et al. law is strain hardening for any value of
the membrane dilatation modulus. The large deformation of a capsule suspended in
hyperbolic pure straining flow is then computed for several membrane constitutive
laws. A capsule with a Mooney–Rivlin membrane bursts through the process of
continuous elongation, whereas a capsule with a Skalak et al. membrane always
reaches a steady state in the range of parameters considered. The small-deformation
analysis of a spherical capsule embedded in a linear shear flow is modified to account
for the effect of the membrane dilatation modulus.
Drag and lift forces on a bubble rising near a
vertical wall in a viscous liquid
Authors: TAKEMURA FUMIO , TAKAGI SHU , MAGNAUDET JACQUES , MATSUMOTO YOICHIRO
Published: July 2002

The two components of the force acting on a clean almost spherical bubble rising
near a plane vertical wall in a quiescent liquid are determined experimentally. This
is achieved by using an apparatus in which a CCD camera and a microscope follow
the rising bubble. This apparatus allows us to measure accurately the bubble radius,
rise speed and distance between the bubble and the wall. Thereby the drag and lift
components of the hydrodynamic force are determined for Reynolds numbers Re
(based on bubble diameter, rise velocity U, and kinematic viscosity ν) less than 40.
The results show the existence of two different regimes, according to the value of
the dimensionless separation L* defined as the ratio between the distance from the
bubble centre to the wall and the viscous length scale ν/U. When L* is O(1) or more,
experimental results corresponding to Reynolds numbers up to unity are found to be
in good agreement with an analytical solution obtained in the Oseen approximation
by adapting the calculation of Vasseur & Cox (1977) to the case of an inviscid bubble.
When L* is o(1), higher-order effects not taken into account in previous analytical
investigations become important and measurements show that the deformation of the
bubble is significant when the viscosity of the surrounding liquid is large enough. In
this regime, experimental results for the drag force and shape of the bubble are found
to agree well with recent theoretical predictions obtained by Magnaudet, Takagi &
Legendre (2002) but the measured lift force tends to exceed the prediction as the
separation decreases.
The density cavitons generated by interactions
of plasma with a moving body in its wake
region in space
Authors: MA SHANJUN , LI XIAOQING
Published: July 2002

Numerical calculations are performed based on a set of equations that
describe the non-steady, nonlinear interactions between a moving body in space and
plasma. The results show that density cavitons and potential solitons are formed
owing to modulational instability if the envelope of the high-frequency modulational field is sufficiently intense.
Stability of force-free magnetic fields versus
magnetic pitch
Authors: HU Y. Q. , LI L.
Published: July 2002

Starting from the one-dimensional energy integral and related stability
theorems given by Newcomb [Ann. Phys (NY)10, 232 (1960)] for a linear pinch
system, this paper analyses the stability of one-dimensional force-free magnetic
fields in cylindrical coordinates (r, θ, z). It is found that the stability of the force-free field is closely related to the radial distribution of the pitch of the field lines:
h(r) = 2πrBz/Bθ. The following three types of force-free fields are proved to be
unstable: (i) force-free fields with a uniform pitch; (ii) force-free fields with a pitch
that increases in magnitude with r in the neighbourhood of r = 0(d[mid ]h[mid ]/dr > 0);
and (iii) force-free fields for which (dh/dr)r=0 = 0, Bθ α rm in the neighbourhood
of r = 0, and (h d2h/dr2)r=0 > −128π2/(2m+4)2. On the other hand, the stability
does not have a definite relation to the maximum of the force-free factor α defined
by [dtri ]×B = αB. Examples will be given to illustrate that force-free fields with an
infinite force-free factor at the boundary are stable, whereas those with a force-free
factor that is finite and smaller than the lowest eigenvalue of linear force-free field
solutions in the domain of interest are unstable. The latter disproves the sufficient
criterion for stability of nonlinear force-free magnetic fields given by Krüger [J.
Plasma Phys.15, 15 (1976)] that a nonlinear force-free field is stable if the maximum
absolute value of the force-free factor is smaller than the lowest eigenvalue of linear
force-free field solutions in the domain of interest.
The stylistic variation of nuclear patterns in Belfast English
Authors: Lowry Orla
Published: July 2002

Informal observation of Belfast speakers finds a larger number of falls in careful speaking styles than the literature would suggest is the case, since Belfast English is reported to be one of the minority varieties of English in which the rise predominates in both interrogatives and declaratives. Three different speaking styles, ranging from careful to spontaneous are elicited from twelve seventeen-year-old Belfast speakers, and the nuclear accents analysed. In the majority of speakers, there is a tendency to use more falling nuclei when the speech style is careful, and fewer or none at all in the most informal style. It is suggested that this is an attempt, in formal contexts, to emulate the prestige variety of the language, which is probably that spoken in Southern England, and uses a preponderance of falling nuclei. Female speakers show more willingness than males to use the features of the prestige variety, which may be explained by social, cultural and complex contextual reasons.
On the categorization of ejectives: data from Witsuwit'en
Authors: Wright Richard , Hargus Sharon , Davis Katharine
Published: July 2002

Results of an acoustic study of root-initial /t th t'/ for eleven speakers of Witsuwit'en (Athabaskan) are presented. Values averaged across speaker means suggest that Witsuwit'en ejectives have a brief period of creaky voice and slow rise time at vowel onset relative to the voiceless unaspirated stops. However, there is considerable inter-speaker variation in VOT and f0 perturbation, with negligible correlation between these measures, contrary to the predictions of the ejective typologies proposed by Lindau (1984) and Kingston (1985). Results of a perception study indicate that the ejective-voiceless unaspirated contrast is more difficult than the other laryngeal contrasts even for native listeners. Implications of the Witsuwit'en data for the categorization of ejectives are discussed.
Reactive approach to on-line path planning for robot manipulators in
dynamic environments
Authors: Mediavilla Margarita , González José Luis , Fraile Juan Carlos , Ramón Perán José
Published: July 2002

This paper describes a new approach to path planning of robot manipulators with many degrees of freedom. It is designed for on-line motion in dynamic and unpredictable environments. The robots react to moving obstacles using a local and reactive algorithm restricted to a subset of its configuration space. The lack of a long-term view of local algorithms (local minima problems) is solved using an off-line pre-planning stage that chooses the subset of the configuration space that minimises the probability of not finding
collision free paths. The approach is implemented and tested on a system of three Scorbot-er IX five link robots.
Modified Jacobian method of transversal passing through the smallest deficiency
singularities for robot manipulators
Authors: Duleba Ignacy , Sasiadek Jerzy Z.
Published: July 2002

This paper proposes a method for transversal passing through
singularities of corank 1, both for nonredundant and redundant robotic manipulators. The method modifies the Jacobian matrix of manipulator's forward kinematics to retrieve its full rank at singularities. Natural candidates for the Jacobian matrix modification are derivatives of determinants of full size sub-matrices of the Jacobian matrix. The method is
illustrated with examples, including a PUMA manipulator and 2-link and 3-link planar manipulators. Some restrictions on the applicability of the method for nonredundant manipulators are also discussed.
Standard Englishes: What do American undergraduates think?
Authors: Karstadt Angela
Published: July 2002

A survey of attitudes to other people's English among students at a university in the United States. Attitudes toward varieties of English as used in European contexts reflect changing viewpoints among their speakers (see Westergren Axelsson; Söderlund & Modiano; and Mobärg; see also Mobärg 1998). In this paper, I focus on the multifaceted attitudes toward varieties of English held by American undergraduate students in one department of English in the United States. I focus on perceptions of varieties of English, particularly on viewpoints of standard and acceptable spoken varieties of English. The wider aim of this project – described here in its early pilot stages – is to identify to what extent American undergraduates accept regional, national, and international varieties of English. A guiding question is whether American undergraduate students expand their view of which varieties of English are standard as the students gain more exposure to varieties that are not their own.
Code-switching and lexical borrowing: Which is what in Ghanaian English?
Authors: Dako Kari
Published: July 2002

Mixed local feelings about the use of local words in the English of Ghana. A Ghanaianism is a vocabulary item peculiar to Ghana. It may be an English item that has undergone a local semantic shift, an item of local origin used consistently in English, or a hybrid of the two. In addition, the term Ghanaian English as used here refers, not to a variety whose features have been more or less fully recognised and described, but broadly to the English used by Ghanaians who have had at least some formal education and are able to use English in some registers. Drawing on a collection of Ghanaianisms compiled over the last 10 years, this paper looks first at some of the prevailing problems in attempting to define the transference phenomena widely identified as code-switching (CS) on the one hand and lexical borrowing (LB) on the other, then at how Ghanaians deal with the phenomenon of borrowing into English at the text level.
Elephant damage to trees of wooded savanna in Zakouma National Park, Chad
Authors: Calenge Clement , Maillard Daniel , Gaillard Jean-Michel , Merlot Leon , Peltier Regis
Published: July 2002

Damage caused by elephants was monitored in two woodland stands of Zakouma National Park (Chad) between February and March 1998. The Acacia seyal savanna was more severely damaged (29.8% of trees damaged of which 13.2% severely) than the Combretaceae savanna (26.5% of trees damaged of which only 4.2% severely). Nearly all severely damaged trees showed resprouts (respectively 86.8% and 88.5% in Combretaceae and A. seyal savannas). Both low damage rate and low mortality rate indicate that no serious ‘elephant problem’ occurred in Zakouma National Park. Elephants selected trees to damage according to species and height. Such selection also occurred for severe damage in A. seyal savanna, but only height affected severity of damage in Combretaceae savanna. In both savannas, the plots close to a water point were the most frequently damaged. In Combretaceae savanna, the distribution of damaged trees was clumped. On the other hand, spatial auto-correlation was not significant for the severity or the frequency of damage in A. seyal savanna. Neither tree density nor diversity of woody species affected the spatial patterns of damage or severe damage.
The development of regular and irregular verb inflection in Spanish child language
Authors: CLAHSEN HARALD , AVELEDO FRAIBET , ROCA IGGY
Published: July 2002

We present morphological analyses of verb inflections produced by 15 Spanish-speaking children (age range: 1;7 to 4;7) taken from longitudinal and cross-sectional samples of spontaneous speech and narratives. Our main observation is the existence of a dissociation between regular and irregular processes in the distribution of errors: regular suffixes and unmarked (non-alternating) stems are over-extended to irregulars in children's inflection errors, but not vice versa. We also found that overregularization errors at all ages are only a small minority of the children's irregular verbs, that the period of overregularization is preceded by a stage without errors, and that the onset of overregularizations is connected to the emergence of obligatory finiteness markings. These findings are explained in terms of the dual-mechanism model of inflection.
The invariant algebraic surfaces of the Lorenz system
Authors: SWINNERTON-DYER SIR PETER
Published: July 2002

The object of this paper is to find all the irreducible algebraic surfaces which (for
special values of the parameters b, r, s) are invariant under the Lorenz system

x˙ = X(x, y, z) = s(y−x),
y˙ = Y(x, y, z) = rx−y−xz,
ż = Z(x, y, z) =−bz+xy. (1)

It is customary in considering the Lorenz system to require the parameters b, r, s to
be all strictly positive; however for this particular problem we shall follow previous
practice in only imposing the condition s ≠ 0. (If s = 0 the equations are trivially
integrable and x is constant on any trajectory; thus x should be regarded as a
parameter and the question discussed in this paper ceases to be a natural one.)
Future Air Traffic Management: Quantitative En Route Safety Assessment Part 1 – Review of Present Methods
Authors: Brooker Peter
Published: July 2002

This is the first of two papers on Quantitative Safety Assessment – vital to the successful introduction of future Air Traffic Management systems. The goal of the two papers is to identify key future questions and the best methods to deal with them. The focus is en route European commercial traffic in controlled airspace, particularly risks from mid-air collision. Part 1 is a critical sketch of the historical context, methods used, and the use of analytical ‘models’ for safety assessment. Aspects covered include safety philosophy principles, safety targets, procedural separation standards, the Reich model and its problems, and radar separation standards.
Location-Based Services: Navigation for the Masses, At Last!
Authors: Beatty Colin
Published: July 2002

This paper, and that following, were first presented at NAV 2001 – Location and Navigation – held at Church House, Westminster, London, 6th to 8th November 2001. Full Proceedings of the Conference are available on CD-ROM from the Royal Institute of Navigation.

This paper covers the current status of wireless network location capabilities, including a view of each method describing the strengths and weaknesses of the various approaches. The paper will describe developments in network-assisted GPS to reveal the capabilities of the so-called high sensitivity receivers. The question of what has to be done to get GPS to work indoors will be answered, together with the impact of this capability on the positioning of mobile telephones fitted with GPS capability. The paper discusses the concepts of integrating terrestrial network-derived location with GPS/GNSS and very short range location systems such as Bluetooth. It will explain how Location-Based Services are operated, when they will become widely available, some of the key applications and the impact of this technology on some of the traditional sciences, in particular mapping. This area of navigation is developing extremely rapidly, with potentially a huge market for navigation on land.
The feeding ecology of the striped possum Dactylopsila trivirgata (Marsupialia: Petauridae) in far north Queensland, Australia
Authors: Rawlins D. R. , Handasyde K. A.
Published: July 2002

The diet of striped possums Dactylopsila trivirgata inhabiting the tropical forests of far north Queensland, Australia, was investigated by observing foraging behaviour and analysing stomach samples collected opportunistically from dead animals. In contrast to non‐dactylopsiline petaurids, which frequently use plant exudates as well as invertebrates, observations on the foraging behaviour of D. trivirgata indicate that it is an opportunistic forager feeding mainly on invertebrates. Animals occasionally fed on plant exudates but these contributed little to the diet. Nine different orders of invertebrates were present in stomach samples, with wood boring coleopteran and lepidopteran larvae, and adult hymenopterans and isopterans being most frequently represented in the diet. This is consistent with the unusual morphological characteristics of D. trivirgata's, such as their elongated fourth finger and powerful jaws, which appear to be adaptations for extracting prey such as wood‐boring larvae. Two of the important prey taxa in the diet (alates of Formicidae, and larvae of Cerambycidae) had a very high fat content (44% and 40% of dry weight, respectively) suggesting that the animals may target prey of high nutritional value. Anatomical investigations indicated that, relative to body weight, the digestive tract of D. trivirgata was shorter than that of most other petaurids. These data further support the idea that D. trivirgata is more reliant on invertebrates than other members of the family Petauridae.
Spermatogonia and spermatocyte ultrastructure in Hoplias malabaricus (Teleostei, Characiformes: Erythrinidae)
Authors: Cunha Negrão José Nazareno , de Carvalho Edmir Daniel , Foresti Fausto , Quagio‐Grassiotto Irani
Published: July 2002

The Hoplias malabaricus primary spermatogonium shows a large nucleus, central nucleolus, and low electron‐dense cytoplasm containing nuages. In cysts, they undergo several mitotic divisions with incomplete cytokinesis, giving rise to secondary spermatogonia. These are smaller than the primary spermatogonia and their nuclei have one or two eccentric nucleoli. Spermatocytes I can be identified by the presence of synaptonemal complexes. Spermatocytes II are smaller than spermatocytes I, displaying roughly compacted chromatin. All these cell types remain interconnected by thick‐walled intercellular bridges, which have membranous reinforcements during mitosis and meiosis. These cell types show a well‐developed endomembranous system, one of the centrioles anchored to the plasma membrane and small nuages. Their mitochondria are large and circular, with few cristae. In the last generations of spermatogonia, the mitochondria are smaller, elongate and have more cristae. In the spermatocytes, the mitochondria are small and round. Similarities found in relation to germ cells of other teleosts are discussed.
Oestrous occurrence in captive female Cricetomys gambianus (Rodentia: Cricetidae)
Authors: Malekani M. , Westlin L. M. , Paulus J. J. , Potgieter H. C.
Published: July 2002

Cricetomys gambianus is an important source of protein for human consumption in many parts of sub‐Saharan Africa. Wild populations are under considerable hunting pressure, suggesting that captive rearing may be desirable. Successful captive‐breeding programmes require a better understanding of reproductive physiology and behaviour. Eight groups containing a total of 68 C. gambianus females were used to characterize the reproductive pattern, including the occurrence and duration of oestrus, the cycle length, the oestrous cyclicity and the mode of ovulation. These female groups were kept in different social and physical environments and examination of vaginal smears were carried out at different periods. Results of the vaginal cytology examination showed two characteristic stages of the cycle: ‘oestrus’ and ‘anoestrus’. Oestrus appeared on average 1.3 times only in one female during 1 month, but its occurrence varied between 0.4 and two times in a month. The mean oestrous length was 3.3 days and ranged from 1.4 to 7.8 days. The average cycle length was 7.9 days but varied between 3 and 15 days. These results showed an irregular cycle pattern and revealed that C. gambianus may be an induced ovulator. Housing events, such as the presence or the absence of a male and the type of cages or rearing room, and the dry and the rainy seasons did not seem to influence the cycle pattern in this species. Further investigations on the basic reproductive biology of Cricetomys are necessary to provide the basis for developing farming methods that will yield high productivity.
The histology and morphometrics of the major salivary glands of four species of wallabies (Marsupialia: Macropodiae) from Kawau Island, New Zealand
Authors: Lentle R. G. , Hume I. D. , Kennedy M. S. , Stafford K. J. , Potter M. A. , Springett B. P. , Haslett S.
Published: July 2002

Allometric analyses of the three major salivary glands of 44 tammar wallabies Macropus eugenii and 58 parma wallabies Macropus parma from Kawau Island, New Zealand, indicate that tammar wallabies have larger parotid glands while parma wallabies have larger mandibular glands. The difference can be related to the importance of cooling in tammars, an arid‐zone species, and the need for greater buffering of forestomach digesta in parma wallabies because of their greater daily food intakes and a higher browse component in their natural diet. Comparisons of sublingual gland size of these two species viewed in terms of their capacity for mucus production suggest that this may be influenced by the need to protect mucosa from mechanical and chemical injury from browse. Sample sizes of brush‐tailed rock‐wallabies Petrogale pencilliata and swamp wallabies Wallabia bicolor were too small for similar statistical comparisons, but they confirmed that salivary gland histology was broadly similar among all four species.
The opera parodies of Florent Carton Dancourt
Authors: POWELL JOHN S.
Published: July 2002

Unlike the opera parodies performed at the Comédie-Italienne in the 1690s and collected by Evariste Gherardi, Dancourt's Angélique et Médor and Renaud et Armide were performed during the première runs of their target operas – Lully's and Quinault's Roland and Armide, respectively. Undoubtedly prompted by Lully's opera monopoly and the draconian restrictions on music and dance that affected the musical repertory at the Comédie-Française, Dancourt's parodies take a tongue-in-cheek view of the madness of opera in general, while specifically satirizing the themes, characters, and operatic situations found in Roland and Armide.
Asymmetric spike patterns for the
one-dimensional Gierer–Meinhardt model:
equilibria and stability
Authors: WARD M. J. , WEI J.
Published: July 2002

Equilibrium solutions to the one-dimensional Gierer–Meinhardt model in the form of sequences of spikes of different heights are constructed asymptotically in the limit of small
activator diffusivity ε. For a pattern with k spikes, the construction yields k1 spikes that have
a common small amplitude and k2 = k−
k1 spikes that have a common large amplitude. A k-
spike asymmetric equilibrium solution is obtained from an arbitrary ordering of the small and
large spikes on the domain. It is shown that such solutions exist when the inhibitor diffusivity
D is less than some critical value Dm that depends upon k1, on k2, and on other parameters
associated with the Gierer–Meinhardt model. It is also shown that these asymmetric k-spike
solutions bifurcate from the symmetric solution branch sk, for which k spikes have equal
height. These asymmetric solutions provide connections between the branch sk and the other
symmetric branches sj , for j = 1,…, k−
1. The stability of the asymmetric k-spike patterns
with respect to the large O(1) eigenvalues
and the small O(ε2) eigenvalues is also analyzed.
It is found that the asymmetric patterns are stable with respect to the large O(1) eigenvalues
when D > De, where De depends on k1 and k2, on certain parameters in the model, and on
the specific ordering of the small and large spikes within a given k-spike sequence. Numerical
values for De are obtained from numerical solutions of a matrix eigenvalue problem. Another
matrix eigenvalue problem that determines the small eigenvalues is derived. For the examples
considered, it is shown that the bifurcating asymmetric branches are all unstable with respect
to these small eigenvalues.
Multiphase flow in a roll press nip
Authors: FITT A. D. , HOWELL P. D. , KING J. R. , PLEASE C. P. , SCHWENDEMAN D. W.
Published: July 2002

A three-phase ensemble-averaged model is developed for the flow of water and air through
a deformable porous matrix. The model predicts a separation of the flow into saturated
and unsaturated regions. The model is closed by proposing an experimentally-motivated
heuristic elastic law which allows large-strain nonlinear behaviour to be treated in a relatively
straightforward manner. The equations are applied to flow in the ‘nip’ area of a roll press
machine whose function is to squeeze water out of wet paper as part of the manufacturing
process. By exploiting the thin-layer limit suggested by the geometry of the nip, the problem
is reduced to a nonlinear convection-diffusion equation with one free boundary. A numerical
method is proposed for determining the flow and sample simulations are presented.
Ghazali and Ash'arism Revisited
Authors: MARMURA MICHAEL E.
Published: July 2002

At the basis of Ghazali's criticisms of Ash'arite kalām is the thesis that its primary function is the defence of traditional Islamic belief, the 'aqida, against the distortions of heretical innovations (al-bida'). Kalām is not an end in itself and it is error to think that the mere engagement in it constitutes the experientially religious. In the I[hdotu]yā' he maintains in effect that when it is pursued as an end in itself, its dogmas can constitute a veil preventive of the attainment of gnosis (ma'rifa). On the other hand, Ash'arite kalām when not pursued as an end in itself can be an aid in the quest after gnosis. This is implicit in his reference (in Kitāb al-Arba'īn) to his own major work of Ash'arite kalām, the Iqti[sdotu]ād fī al-i'tiqād, where he states that “it goes deeper in ascertaining [the truth] and is closer to knocking at the doors of gnosis than the official discourse encountered in the books of the mutakallimīn.” The I[hdotu]yā' abounds with homilies, guides for the pious, particularly for those seeking mystical knowledge. Ash'arism pervades such homilies. Thus in Kitāb al-Tawba, Ghazali formulates, analyzes and defends the concept of human choice in Ash'arite terms. He thus argues that each of the ingredients of this concept - knowledge, power, the decisive will, as well as the ensuing choice - is individually the direct creation of God. Not that the argument for this concept yields experiential knowledge of its meaning within the cosmic scheme of things. For Ghazali such knowledge is only attained through mystical vision. But the Ash'arite argument, when not pursued as an end in itself, can be an aid to the seekers of gnosis. It can bring them closer to knocking at its doors.
The Medieval Astrologization of Aristotle's Biology: Averroes on the Role of the Celestial Bodies in the Generation of Animate Beings
Authors: Freudenthal Gad
Published: July 2002

How do the variegated forms of sublunar substances (the elements, homoeomerous substances, plants, animals) arise in prime matter? Averroes throughout his life believed that “a principle from without” was involved, but changed his mind over its identity. While in an early period of his life he maintained that all forms emanate from the active intellect, he later discarded that metaphysical notion and sought to develop a more naturalistic, astrologically inspired account, which identified the heavenly bodies as the source of sublunar forms. Comparing different versions of Averroean texts, this paper seeks to spell out how, in Averroes' view, the heavenly bodies generate forms in matter. Averroes claims that this is brought about by means of their “heats,” an answer that is however problematic seeing that in the Aristotelian cosmology the celestial realm is quality-less. The paper examines Averroes' ideas on the relationship between light and heat, concluding that the Commentator was unable to integrate the postulate that the heavenly bodies inform matter within his Aristotelian theory of matter.
Lead and Tin in Arabic Alchemy
Authors: El-Eswed Bassam I.
Published: July 2002

The present article is devoted to two issues. The first is the identification of lead and tin in medieval Arabic alchemy. The second is the investigation of whether Arabic alchemists differentiate between these problematic substances or not. These two issues are investigated in the light of a comparison which is made between the facts that are stated about the two problematic substances in the original Arabic alchemical works and those stated in modern chemical literature. It is proved that Arabic alchemists made a sharp distinction between lead and tin. Also, it becomes clear that these two metals were used in a satisfactory purity in the era of medieval Arabic alchemy. As a consequence of the present study, some conclusions are drawn about the existence of some categories of ‘derivatives’ of fusible bodies in Arabic alchemy which are degenerate to modern categories of oxides, carbonates, etc.
Motivation and task performance in a task-based web-based tandem project
Authors: APPEL CHRISTINE , GILABERT ROGER
Published: July 2002

The objective of this paper is to describe a task-based project in tandem
via e-mail, and to discuss the effects of motivation on task performance. In this project, a group
of Irish students and a group of Spanish students are asked to carry out a series of tasks in
collaboration with their tandem partners via e-mail by means of a web page especially designed for
the project. Half the message is meant to be written in the student’s native language and
half in the target language, and students are also encouraged to correct one another. The goal
behind our research is to discuss the effects of motivation on task performance. We argue that
resource directing (such as reasoning demands) and resource depleting factors (such as prior
knowledge) which belong to task complexity in Robinson’s model (Robinson, 2001) are
closely connected to affective variables which, as is the case with motivation, belong to task
difficulty. Motivational factors like interest in the meanings to be exchanged, involvement in
the decision-making process, students’ expertise in the topic, media and materials used,
and the diffusion of outcomes among others have strong effects on task performance, and should
therefore be considered together with complexity variables.
String and graph reduction systems for gene assembly in ciliates
Authors: EHRENFEUCHT ANDRZEJ , PETRE ION , PRESCOTT DAVID M. , ROZENBERG GRZEGORZ
Published: July 2002

Ciliates have developed a unique nuclear dualism, having two nuclei of different
functionality: the germline micronucleus and the somatic macronucleus. The way that
ciliates assemble the macronuclear genes after cell mating constitutes one of the most
intricate DNA processings in living organisms. This processing is also very interesting from
the computational point of view. In this paper, we investigate the operations of loop excision
and hairpin excision/reinsertion used in the assembly process. In particular, we consider
three levels of formalization of this process, culminating in graph reduction systems.
A NEW NICKEL-ACCUMULATING SPECIES OF ALYSSUM (CRUCIFERAE) FROM WESTERN TURKEY
Authors: ADIGÜZEL N. , REEVES R. D.
Published: July 2002

A new species of Alyssum L. (Cruciferae) from Western Turkey is described and illustrated: Alyssum dudleyi N. Adıgüzel & R.D. Reeves.
REVISION OF CYCLOLOBIUM (LEGUMINOSAE-PAPILIONOIDEAE)
Authors: WARWICK M. C. , PENNINGTON R. T.
Published: July 2002

Cyclolobium (Leguminosae-Papilionoideae-Millettieae) has traditionally comprised six species, but doubts have been expressed as to their distinctness. Analysis of morphological variation across the range of the genus indicates Cyclolobium comprises a single species, C. brasiliense Benth.
Flora Europaea on CD ROM. Cambridge University Press. 2001. ISBN 0 521 77811 5. £350.00. [DOI: 10.10M/S0960428602230152]
Authors: MILLIKEN W.
Published: July 2002

..
Finite elements in computational electromagnetism
Authors: Hiptmair R.
Published: July 2002

This article discusses finite element Galerkin schemes for a number of linear
model problems in electromagnetism. The finite element schemes are introduced
as discrete differential forms, matching the coordinate-independent
statement of Maxwell's equations in the calculus of differential forms. The
asymptotic convergence of discrete solutions is investigated theoretically. As
discrete differential forms represent a genuine generalization of conventional
Lagrangian finite elements, the analysis is based upon a judicious adaptation
of established techniques in the theory of finite elements. Risks and difficulties
haunting finite element schemes that do not fit the framework of discrete differential
forms are highlighted.
The immersed boundary method
Authors: Peskin Charles S.
Published: July 2002

This paper is concerned with the mathematical structure of the immersed
boundary (IB) method, which is intended for the computer simulation of
fluid–structure interaction, especially in biological fluid dynamics. The IB
formulation of such problems, derived here from the principle of least action,
involves both Eulerian and Lagrangian variables, linked by the Dirac
delta function. Spatial discretization of the IB equations is based on a fixed
Cartesian mesh for the Eulerian variables, and a moving curvilinear mesh for
the Lagrangian variables. The two types of variables are linked by interaction
equations that involve a smoothed approximation to the Dirac delta function.
Eulerian/Lagrangian identities govern the transfer of data from one mesh to
the other. Temporal discretization is by a second-order Runge–Kutta method.
Current and future research directions are pointed out, and applications of
the IB method are briefly discussed.
Numerical methods for large eigenvalue problems
Authors: Sorensen Danny C.
Published: July 2002

Over the past decade considerable progress has been made towards the numerical
solution of large-scale eigenvalue problems, particularly for nonsymmetric
matrices. Krylov methods and variants of subspace iteration have been improved
to the point that problems of the order of several million variables can
be solved. The methods and software that have led to these advances are
surveyed.
Some Exact Results and New Asymptotics for
Hypergraph Turán Numbers
Authors: MUBAYI DHRUV
Published: July 2002

Given a family [Fscr ] of r-graphs, let ex(n, [Fscr ]) be the maximum number of edges in an n-vertex
r-graph containing no member of [Fscr ]. Let C(r)4 denote the family of r-graphs with distinct
edges A, B, C, D, such that A
∩
B = C
∩
D = Ø
and A ∪ B = C ∪ D. For s1 [les ] … [les ]
sr, let
K(r) (s1,…,sr) be the complete r-partite r-graph with parts of sizes s1,…,sr.

Füredi conjectured over 15 years ago that ex(n,C(3)4) [les ]
(n2) for sufficiently large n. We prove the weaker result

ex(n, {C(3)4, K(3)(1,2,4)}) [les ] (n2).

Generalizing a well-known conjecture for the Turán number of bipartite graphs, we
conjecture that

ex(n, K(r)(s1,…,sr)) = Θ(nr−1/s),

where s = Πr−1i=1si.
We prove this conjecture when s1 = … = sr−2 = 1 and

(i) sr−1 = 2, (ii) sr−1 = sr = 3, (iii)sr > (sr−1−1)!.

In cases (i) and (ii), we determine the asymptotic value of ex(n,K(r)(s1,…,sr)).

We also provide an explicit construction giving

ex(n,K(3)(2,2,3)) > (1/6−o(1))n8/3.

This improves upon the previous best lower bound of Ω(n29/11) obtained by probabilistic
methods. Several related open problems are also presented.
Exact Expectations and Distributions
for the Random Assignment Problem
Authors: ALM SVEN ERICK , SORKIN GREGORY B.
Published: July 2002

A generalization of the random assignment problem asks the expected cost of the minimum-cost matching of cardinality k in a complete bipartite graph Km,n, with independent random
edge weights. With weights drawn from the exponential distribution with intensity 1, the
answer has been conjectured to be

Σi,j≥0, i+j<k1/(m−i)(n−j).

Here, we prove the conjecture for k [les ] 4, k = m = 5, and k = m = n = 6, using
a structured, automated proof technique that results in proofs with relatively few cases.
The method yields not only the minimum assignment cost's expectation but the Laplace
transform of its distribution as well. From the Laplace transform we compute the variance
in these cases, and conjecture that, with k = m = n
→ ∞, the variance is 2/n + O(log n/n2).
We also include some asymptotic properties of the expectation and variance when k is
fixed.
Editorial
Authors: Tait John , Boguraev Branimir , Jacquemin Christian
Published: July 2002

This is the first issue of Volume 8, and we thought we would take this opportunity to
bring readers of Natural Language Engineering up-to-date with various developments
with the journal.
New meanings from old buildings
Authors: Blundell Jones Peter , Sergeant John
Published: July 2002

The three modest house projects described here are by three fellow
travellers — the two authors and David Lea — interested in the
Organic side of Modernism. Conversational partners who have
worked together in various capacities over many years, they share a
common conviction about ‘working with the given’ (pp.305—311).
The use of photographic rates to estimate densities of tigers and other cryptic mammals: a comment on misleading conclusions
Authors: Jennelle Christopher S. , Runge Michael C. , MacKenzie Darryl I.
Published: July 2002

The search for easy‐to‐use indices that substitute for direct estimation of animal density is a common theme in wildlife and conservation science, but one fraught with well‐known perils (Nichols & Conroy, 1996; Yoccoz, Nichols & Boulinier, 2001; Pollock et al., 2002). To establish the utility of an index as a substitute for an estimate of density, one must: (1) demonstrate a functional relationship between the index and density that is invariant over the desired scope of inference; (2) calibrate the functional relationship by obtaining independent measures of the index and the animal density; (3) evaluate the precision of the calibration (Diefenbach et al., 1994). Carbone et al. (2001) argue that the number of camera‐days per photograph is a useful index of density for large, cryptic, forest‐dwelling animals, and proceed to calibrate this index for tigers (Panthera tigris). We agree that a properly calibrated index may be useful for rapid assessments in conservation planning. However, Carbone et al. (2001), who desire to use their index as a substitute for density, do not adequately address the three elements noted above. Thus, we are concerned that others may view their methods as justification for not attempting directly to estimate animal densities, without due regard for the shortcomings of their approach.
Phylogeny and the selectivity of extinction in Australian marsupials
Authors: Johnson Christopher N. , Delean Steven , Balmford Andrew
Published: July 2002

Recent studies have suggested that contemporary losses of species are unevenly distributed over phylogenies. Here, we show that species of Australian marsupials are at higher risk if they belong to genera that are species‐poor, old or phylogenetically distinct. Extinction risk in this group is also related to habitat and body size, being higher for species from non‐forested habitats and of intermediate body size. We tested the extent to which the phylogenetic selectivity of extinction was explained by this ecological pattern. We found that while genus size and distinctiveness explain no variation in extinction risk that is not accounted for by habitat and body size, there is a significant residual association of genus age with extinction risk. This suggests that while species in small and distinctive genera are at high risk because they are overrepresented in non‐forested habitats and intermediate body size classes, species in old genera are at higher risk over the range of body sizes and habitats and may be intrinsically vulnerable to extinction.
Fitness heterogeneity and viability of restored populations
Authors: Robert Alexandre , Couvet Denis , Sarrazin François
Published: July 2002

We develop a stochastic model of population viability which explicitly links demography and genetics in order to examine the consequences for extinction dynamics of different levels of heritable fitness variance within a population. We particularly focus on situations in which a local small population is artificially built with individuals that were taken from several large source populations. Our results suggest that different levels of fitness variability within a population (due to partially recessive deleterious alleles rather than local adaptation) have a large influence on its viability. Moreover, the optimal level of fitness variance for maximizing population persistence is a function of the species life‐cycle. Two mechanisms with opposite effects are mainly responsible for the different patterns of extinction obtained depending on the life‐cycle, (1) purging of deleterious alleles, (2) demographic stochasticity. For high growth rate or long‐lived species, a high fitness variance decreases short‐term viability and increases long‐term viability. In contrast, for other cases, a high fitness variance increases both short‐ and long‐term viability.
Governing from the Centre: Core Executive Capacity in Britain and Japan
Authors: Holliday Ian , Shinoda Tomohito
Published: July 2002

The article contributes to debates about core executive capacity by analyzing the British and Japanese cases. First it examines the historical development, contemporary structures and current operations of the two cases. Then it compares their performance in five key areas: overseeing government policy in the domestic sphere; overseeing government policy in the external sphere; managing executive relations with the legislature; overseeing public finances; and managing public relations. It finds that the performance of the two systems is variable both internally across distinct areas of business and, to a lesser extent, comparatively across similar areas. Overall, however, the British core executive is shown to have considerably greater capacity for coordinating and managing policy flows through the system than the Japanese. Governing from the centre is more feasible in Britain than in Japan.