bluuebunny/crossref_metadata_2025 huggingface dataset:
Streamwise oscillations of a cylinder in a steady current.
Part 1. Locked-on states of vortex formation and loading
Authors: CETINER O. , ROCKWELL D.
Published: July 2002

Streamwise oscillations of a circular cylinder in a steady uniform flow are investigated
experimentally using a technique of high-image-density particle image velocimetry,
in conjunction with instantaneous force measurements. This approach allows insight
into the relationship between the loading and the patterns of vorticity and streamline
topology in the near wake.

In analogy with the classical locked-on state arising from transverse oscillations of
a cylinder in uniform flow, it is possible to attain either locked-on or quasi-locked-on
states due to streamwise oscillations. In these cases, however, the repetitive signature
of the transverse force is not sinusoidal; rather, it is strongly modulated and the
corresponding spectra can exhibit several sharply defined peaks. The predominant
peak can vary over a remarkably wide range, extending from the subharmonic to the
third harmonic of the cylinder oscillation frequency; for certain locked-on states of
the transverse force signature, the spectral peak at the cylinder oscillation frequency
is actually suppressed. Corresponding instantaneous traces and spectra of the in-line
force simply show dominance of the spectral peak at the cylinder oscillation frequency.
Further interpretation of the loading is provided in terms of Lissajous patterns of the
transverse and in-line force coefficients.

All of these features are related to the instantaneous patterns of vortex formation
in the near wake. During a typical cycle of the cylinder oscillation, these patterns can
be divided into two broad categories: Kármán-like shedding; and a nearly ‘frozen’
array of shed vortices. The order of occurrence of these basic patterns during an
oscillation cycle dictates the instantaneous signatures and time-averaged spectra of
the transverse force.
Coherent structure in the turbulent planar jet.
Part 1. Extraction of proper orthogonal decomposition eigenmodes and
their self-similarity
Authors: GORDEYEV S. V. , THOMAS F. O.
Published: July 2002

In this paper the coherent structure in the similarity region of the turbulent planar
jet is examined experimentally by application of the proper orthogonal decomposition
(POD). In particular, twin cross-stream rakes of X-wire probes are used to
take cross-spectral measurements with different spanwise separations between the
rakes and at several locations throughout the similarity region. The resulting POD
spatial eigenfunctions for each of the three velocity components depend on cross-stream spatial coordinate, Strouhal number, and spanwise wavenumber. Corresponding
eigenvalue distributions are obtained in Strouhal number–spanwise wavenumber
space. Eigenvalue convergence is demonstrated to be rapid. When properly scaled
the eigenfunctions and eigenvalues are shown to exhibit self-similarity though the
streamwise location at which this commences depends on the particular velocity
component. The results suggest that the flow supports a planar structure aligned
in the spanwise direction as well as an essentially three-dimensional structure with
asymmetrical shape in the cross-stream direction and pseudo-periodically distributed
in the spanwise direction. Comparison of the single- and dual-rake implementations
of the POD presented in this paper demonstrate that measurements confined to a
single plane are incapable of properly extracting the planar modes. Rather, the single-rake implementation results in modes that appear to be a weighted sum of modes
corresponding to different spanwise wavenumbers.
Exact solutions for steady bubbles in a Hele-Shaw cell with rectangular geometry
Authors: VASCONCELOS GIOVANI L.
Published: July 2002

Exact solutions are presented for an arbitrary number of steadily moving bubbles in
a Hele-Shaw channel when surface tension is neglected. According to the symmetry
displayed by the bubbles, the solutions are classified into two groups: (i) solutions
where the bubbles are symmetrical about the channel centreline and (ii) solutions in
which the bubbles have fore-and-aft symmetry. The general solutions are expressed in
integral form but in some special cases analytic solutions in terms of elliptic integrals
are found. The possible relevance of these exact solutions to experiments is also
briefly discussed.
Mass transport in viscous flow under a progressive water wave
Authors: GWINN ALLAN W. , JACOBS S. J.
Published: July 2002

We consider two-dimensional free surface flow caused by a pressure

wavemaker in a

viscous incompressible fluid of finite depth and infinite horizontal extent.
The

governing equations are expressed in dimensionless form, and attention
is

restricted to

the case δ[Lt ]ε[Lt ]1, where δ is the characteristic

dimensionless thickness of a Stokes

boundary layer and ε is the Strouhal number. Our aim is to provide
a

global picture of the flow, with emphasis on the steady streaming velocity.

The asymptotic flow structure near the wavenumber is found to consist
of five

distinct vertical regions: bottom and surface Stokes layers of

dimensionless thickness

O(δ), bottom and surface Stuart layers of dimensionless

thickness O(δ/ε) lying outside

the Stokes layers, and an irrotational outer region of dimensionless

thickness O(1).

Equations describing the flow in all regions are derived, and the lowest-order
steady

streaming velocity in the near-field outer region is computed analytically.

It is shown that the flow far from the wavemaker is affected by thickening
of the

Stuart layers on the horizontal length scale

O[(ε/δ)2], by viscous wave
decay on the

scale O(1/δ), and by nonlinear interactions on the scale

O(1/ε2). The analysis of the

flow in this region is simplified by imposing the restriction

δ=O(ε2), so that all three

processes take place on the same scale. The far-field flow structure is
found

to consist

of a viscous outer core bounded by Stokes layers at the bottom boundary
and water

surface. An evolution equation governing the wave amplitude is derived
and solved

analytically. This solution and near-field matching conditions are employed
to

calculate the steady flow in the core numerically, and the results are
compared with

other theories and with observations.
Salt-finger convection generated by lateral heating

of a solute gradient
Authors: CHEN C. F. , CHEN FALIN
Published: July 2002

When a tank of fluid with a solute gradient

is subjected to lateral heating, a series of

horizontal convection cells is generated when the critical condition

is exceeded. This

phenomenon has been observed experimentally and simulated by two-dimensional

numerical schemes by a number of previous investigators. In each of the
convection

cells, relatively warm and solute-rich fluid flows from the hot to

the cold wall along the

top of the cell while the return of the relatively cool and solute-poor

fluid is along the

bottom of the cell. This situation is conducive to the onset of salt

fingers. We recently

performed a series of such experiments with salt-water and

ethanol–water solutions. By

using flow visualization techniques, salt fingers in longitudinal

rolls typical of those

occurring in shear flows were observed. Salt fingers were observed as soon
as

convection was initiated, and they advanced with the convection front.
Experiments

with an ethanol–water solution showed that salt fingers

can be generated by flows

driven by a surface tension gradient and that the effect of solute concentration
on

surface tension plays an important role in the process.
Three-dimensional instability of Burgers and
Lamb–Oseen vortices in a strain field
Authors: ELOY CHRISTOPHE , LE DIZÈS STÉPHANE
Published: July 2002

The linear stability of Burgers and Lamb–Oseen vortices is
addressed when the
vortex of circulation Γ and radius δ is subjected
to an additional strain
field of rate s perpendicular to the vorticity axis. The resulting
non-axisymmetric
vortex is analysed in the limit of large Reynolds number
RΓ=Γ/v and
small strain
s[Lt ]Γ/δ2 by considering the

approximations obtained by Moffatt et al. (1994) and Jiménez
et al.
(1996) for each case respectively. For both vortices, the TWMS instability
(Tsai &
Widnall 1976; Moore & Saffman 1975) is shown to be active, i.e. stationary
helical
Kelvin waves of azimuthal wavenumbers m=1 and m=−1
resonate and are
amplified by the external strain in the neighbourhood of critical axial
wavenumbers
which are computed. The additional effects of diffusion for the Lamb–Oseen
vortex
and stretching for the Burgers vortex are proved to limit in time the resonance.
The
transient growth of the helical waves is analysed in detail for the distinguished
scaling
s∼Γ/
(δ2R1/2Γ).
An
amplitude equation describing the resonance is obtained and the maximum
gain of the wave
amplitudes is calculated. The effect of the vorticity
profile on the instability characteristic as well as of a time-varying
stretching rate
are analysed. In particular the stretching rate maximizing the instability
is calculated.
The results are also discussed in the light of recent observations in experiments
and
numerical simulations. It is argued that the Kelvin waves resonance mechanism
could
explain various dynamical behaviours of vortex filaments in turbulence.
Mechanisms for generating coherent
packets of hairpin vortices in channel flow
Authors: ZHOU J. , ADRIAN R. J. , BALACHANDAR S. , KENDALL T. M.
Published: July 2002

The evolution of a single hairpin vortex-like structure in the mean turbulent field of
a low-Reynolds-number channel flow is studied by direct numerical simulation. The
structure of the initial three-dimensional vortex is extracted from the two-point spatial
correlation of the velocity field by linear stochastic estimation given a second-quadrant
ejection event vector. Initial vortices having vorticity that is weak relative to the mean
vorticity evolve gradually into omega-shaped vortices that persist for long times and
decay slowly. As reported in Zhou, Adrian & Balachandar (1996), initial vortices that
exceed a threshold strength relative to the mean flow generate new hairpin vortices
upstream of the primary vortex. The detailed mechanisms for this upstream process
are determined, and they are generally similar to the mechanisms proposed by Smith et
al. (1991), with some notable differences in the details. It has also been found that new
hairpins generate downstream of the primary hairpin, thereby forming, together with
the upstream hairpins, a coherent packet of hairpins that propagate coherently. This
is consistent with the experimental observations of Meinhart & Adrian (1995). The
possibility of autogeneration above a critical threshold implies that hairpin vortices
in fully turbulent fields may occur singly, but they more often occur in packets. The
hairpins also generate quasi-streamwise vortices to the side of the primary hairpin
legs. This mechanism bears many similarities to the mechanisms found by Brooke
& Hanratty (1993) and Bernard, Thomas & Handler (1993). It provides a means
by which new quasi-streamwise vortices, and, subsequently, new hairpin vortices can
populate the near-wall layer.
High-order structure functions of turbulence
Authors: VAN DE WATER WILLEM , HERWEIJER JANINE A.
Published: July 2002

The scaling behaviour of high-order structure functions
Gp(r)
=〈(u(x+r)−u(x))p〉 is studied in a variety of laboratory turbulent flows. The statistical accuracy of the structure function benefits from novel instrumentation for its real-time measurement.
The nature of statistical errors is discussed extensively. It is argued that integration
times must increase for decreasing separations r. Based on the statistical properties of
probability density functions we derive a simple estimate of the required integration
time for moments of a given order. We further give a way for improving this accuracy
through careful extrapolation of probability density functions of velocity differences.

Structure functions are studied in two different kinematical situations. The (standard)
longitudinal structure functions are measured using Taylor's hypothesis. In
the transverse case an array of probes is used and no recourse to Taylor's hypothesis
is needed. The measured scaling exponents deviate from Kolmogorov's (1941)
prediction, more strongly so for the transverse exponents.

The experimental results are discussed in the light of the multifractal model that
explains intermittency in a geometrical framework. We discuss a prediction of this
model for the form of the structure function at scales where viscosity becomes of
importance.
Aerosol particle transport and deposition in
vertical and horizontal turbulent duct flows
Authors: ZHANG HAIFENG , AHMADI GOODARZ
Published: July 2002

Aerosol particle transport and deposition in vertical and horizontal turbulent duct
flows in the presence of different gravity directions are studied. The instantaneous fluid
velocity field is generated by the direct numerical simulation of the Navier–Stokes
equation via a pseudospectral method. A particle equation of motion including Stokes
drag, Brownian diffusion, lift and gravitational forces is used for trajectory analysis.
Ensembles of 8192 particle paths are evaluated, compiled, and statistically analysed.
The results show that the wall coherent structure plays an important role in the particle
deposition process. The simulated deposition velocities under various conditions are
compared with the available experimental data and the sublayer model predictions.
It is shown that the shear velocity, density ratio, the shear-induced lift force and the
flow direction affect the particle deposition rate. The results for vertical ducts show
that the particle deposition velocity varies with the direction of gravity, and the effect
becomes more significant when the shear velocity is small. For horizontal ducts, the
gravitational sedimentation increases the particle deposition rate on the lower wall.
Lesotho's general election of 1998: rigged or de rigeur?
Authors: Southall Roger , Fox Roddy
Published: July 2002

The official result of Lesotho's general election of 1998, which saw a 79 out
of 80 seat victory for the ruling Lesotho Congress of Democrats (LCD), was
repudiated by the opposition, notably the former ruling Basotho National
Party (BNP) and the Basutoland Congress Party (BCP). These latter parties
were historic enemies but forged an alliance of convenience to contest the
outcome of the election. By mobilising their supporters to occupy Maseru they
successfully paralysed the capacity of the LCD to govern. After diplomatic
preliminaries, this led to military intervention by South Africa and Botswana
in September 1998 and their brokering of an agreement which restored the
LCD to power, on the condition that a new election would be held within
eighteen months, with the rules for that contest being discussed between the
parties in the interim. That election has now been scheduled for April 2000.

The article reviews the conduct and result of the general election of 1998.
It concludes that the opposition's objections were largely spurious, but notes
that the unbalanced nature of the LCD's victory – a product of the first-past-the-post electoral system – was a major cause of the wider crisis. It therefore
proposes that any lasting settlement of political differences in Lesotho is going
to require a new electoral system which will allow for a more inclusive
outcome.
Generation of kinetic Alfvén waves by upper-hybrid pump waves
Authors: YUKHIMUK V. , VOITENKO Yu. , FEDUN V. , YUKHIMUK A.
Published: July 2002

The nonlinear mechanism for kinetic-Alfvén-wave (KAW) excitation
by upper-hybrid
waves (UHWs) is discussed. Taking into account perpendicular dispersion

of KAWs, caused by effects of finite ion Larmor radius and electron inertia,
we
examine a new channel for UHW decay, in which a pump UHW decays into another

UHW and an ultralow-frequency wave, KAW: UHW→KAW+UHW. A nonlinear

dispersion relation is derived, and the growth rate of the parametric decay
instability
is calculated for a pump UHW propagating at an arbitrary angle to the background

magnetic field. We find that the resulting KAWs often have a two-peaked

spectrum with different perpendicular dispersions. Using satellite observations,
the
analytical results are applied to show that the considered process represents
an
effective mechanism for KAW generation and the consequent spreading of
the UHW
spectrum in the Earth's magnetosphere and solar corona.
Stabilization of the kinetic internal kink mode
by a sheared poloidal flow
Authors: NAITOU HIROSHI , KOBAYASHI TOSHIMITSU , TOKUDA SHINJI
Published: July 2002

The effects of a sheared poloidal flow on the m = 1 (poloidal mode number) and
n = 1 (toroidal mode number) kinetic internal kink mode are simulated by the
linearized version of the gyro-reduced MHD code, GRM3D-2F, based on a two-field
and two-fluid gyro-reduced MHD model, including the kinetic effects of electron
inertia and the perturbed electron pressure gradients along the magnetic field. A
parameter study for different values of de
(collisionless electron skin depth) with
a fixed value of ρs = 0 (ion Larmor radius estimated
by the electron temperature)
shows that the smaller-de case, which has the
smaller growth rate, is stabilized by
the smaller sheared poloidal flow. When ρs is raised to
ρs > de for a fixed value of
de, the instability is stabilized by the smaller
shear flow compared with the case of
ρs < de, although
the growth rate without the flow is larger for
ρs > de. Since
de
is very much less than the minor radius, and
ρs > de for the existing and future
experiments, it is possible that even a quite small sheared poloidal flow may have
a crucial influence on the kinetic internal kink mode.
Infestation by excavating sponges on the oyster (Ostrea edulis) populations of the Blanes littoral zone (north-western Mediterranean Sea)
Authors: Rosell Dolors , Uriz Maria-Jesús , Martin Daniel
Published: July 2002

In order to estimate the degree of implantation of excavating sponges in the oyster populations from the littoral zone at Blanes (north-western Mediterranean Sea), a representative sample of oysters (Ostrea edulis) was collected from depths between 0.5 and 4 m in 1986. All oysters were infested by the excavating sponges Cliona viridis and Cliona celata. Infestation affected always and exclusively the lower valve always reaching the inner side. The degree of infestation proved to be independent of oyster size and weight. Colonization by contact was considered the main means of dispersion of these sponges within the oyster population. Cliona viridis and C. celata emerged as the single excavating species able to effectively compete with other non-excavating or excavating organisms when trying to colonize the particular calcareous substrate provided by oyster shells in the north-western Mediterranean Sea.
A new species of marine yeast Kluyveromyces penaeid isolated from the heart of penaeid shrimp Penaeus chinensis
Authors: Tong Shang-Liang , Miao Hong-Zhi
Published: July 2002

A new species of marine yeast Kluyveromyces penaeid (Saccharomycetoideae) was isolated from the heart tissue of a subadult shrimp Penaeus chinensis during tissue culture. The yeast grew well in seawater supplemented with 2% shrimp extract, but did not grow in chemically defined media. The vegetative cells reproduced by multilateral budding and formed rudimentary pseudohyphae occasionally. Asci were spheroidal and evanescent containing 2–13 smooth or oval ascospores. The best temperature for the yeast to grow was 20–25°C and 37°C was lethal. The yeast grew well in half to full strength seawater supplemented with shrimp extract, but did not grow in 25% strength seawater. The carbohydrate fermentation test was positive, the diazonium blue B and urea hydrolysis tests were negative.
Atheists, Gurus and Fanatics: Rabindranath Tagore's ‘Chaturanga’ (1916)
Authors: Radice William
Published: July 2002

Dr Kaiser Haq gives his fine new English translation of Tagore's novella Chaturanga the title ‘Quartet’. This elegantly preserves much of the meaning of the Bengali title, for not only does it imply the ‘four limbs’ or ‘four parts’ that make up the novella—the four chapters that were originally published separately in consecutive issues of Sabujpatra (November–February, 1915–16)—but also, as in a string quartet, the interplay between the four characters that the chapters are named after. Since Tagore was always alert to the full meaning or etymology of names, perhaps we should also remember that a chaturanga in epic India was a complete army comprising elephants, chariots, cavalry and infantry. This matches the grandeur of the novella, the vigour and precision of its prose, and the moral and spiritual battles that are its subject. Finally, chaturanga as a name for a chess game (technically a four-player version of the game) evokes both the intellectualism of the book and its concentrated passion.
Trial release of Père David's deer Elaphurus davidianus in the Dafeng Reserve, China
Authors: Hu Huijian , Jiang Zhigang
Published: July 2002

The Critically Endangered Père David's deer Elaphurus davidianu became extinct in the wild in China in about 1900, and the only surviving animals were held in captivity at Woburn Abbey in the UK. During 1985–1987, individuals were returned to China, and subsequent growth of the captive population in enclosures at Dafeng Reserve necessitated a trial release of a small group of deer as a prelude to further releases. Seven individuals were released into the unfenced coastal region of the Dafeng Reserve in 1998. Behaviour, daily activity rhythm, habitat selection, activity range and body condition were recorded for six months after release. The deer exhibited initial changes in behaviour, but returned to their pre-release patterns about four weeks after release, and by six weeks after release their body condition had improved compared to their previous condition in captivity. They left the Reserve and began to forage on farmland, causing conflict with local people. Further releases should be into areas with either a natural or artificial boundary in order to avoid unmanageable levels of conflict between the needs of the deer and those of farmers.
High prevalence of Echinococcus multilocularis in urban red
foxes (Vulpes vulpes) and voles (Arvicola terrestris) in the
city of Zürich, Switzerland
Authors: HOFER S. , GLOOR S. , MÜLLER U. , MATHIS A. , HEGGLIN D. , DEPLAZES P.
Published: July 2002

Over a period of 26 months from January 1996 to February 1998, 388 foxes from the city of Zürich, Switzerland, were
examined for intestinal infections with Echinococcus multilocularis and other helminths. The prevalence of E. multilocularis
in foxes sampled during winter increased significantly from 47% in the urban to 67% in the adjacent recreational area,
whereas prevalence rates of other helminths were similar in both areas. Seasonal differences in the prevalence of E.
multilocularis were only found in urban subadult male foxes which were significantly less frequently infected in summer
than in winter. The distribution of the Echinococcus biomass, as expressed by worm numbers per fox was overdispersed
in 133 infected foxes randomly sampled in winter. Ten of these foxes (8%) were infected with more than 10000 specimens
and carried 72% of the total biomass of E. multilocularis (398653 worms). Prevalences did not differ significantly in these
foxes in regard to age and sex but worm burdens were significantly higher in subadult foxes as compared with adult foxes.
In voles (Arvicola terrestris) trapped in a city park of Zürich, E. multilocularis metacestodes were identified by morphological
examination and by PCR. The prevalence was 20% among 60 rodents in 1997 and 9% among 75 rodents in 1998.
Protoscoleces occurred in 2 of the cases from 1997. The possible risk for human infection is discussed with respect to the
established urban E. multilocularis cycle.
Pointing with focussing devices
Authors: Schultz Wolfram
Published: July 2002

Evolutionary pressure selects for the most efficient way of
information processing by the brain. This is achieved by focussing
neuronal processing onto essential environmental objects, by using
focussing devices as pointers to different objects rather than
reestablishing new representations, and by using external storage
bound to internal representations by pointers. Would external storage
increase the capacity of cognitive processing?
Sociological research on age: legacy and
challenge: a comment
Authors: ANDERSSON LARS
Published: July 2002

As the ‘aging and society’ paradigm examines structure in its own
right, it should have an immediate appeal to sociologists. On the one
hand it can be seen as a schematic for gerontology or research on
human development and, on the other, as a theory or paradigm in its
own right. I see the various parts and phases of the paradigm as a
learning process, where stopping somewhere half-way is risky: one has
to go the whole hog before really prospering from its logic.

To focus on individuals and social change together requires analyses
that, in the words of Hardy and Waite (1997), can assess the nature
and temporal patterns of individual behaviour, while simultaneously
attending to the manner in which this behaviour is enclosed in different
organisational structures that are themselves changing, whether
synchronically or asynchronically.

The Rileys have always reminded us of the dangers of neglecting
structure, or of treating it as a mere contextual characteristic in
people's lives, particularly in the form of life course reductionism. In
addition, however, the temporal aspects of structures are important.
There is a risk in using solely the various social situations of different
cohorts as the basis of analysis. Mere comparison with an older cohort
causes the ‘surrounding structure’ to appear too static. The explanation
or understanding of a phenomenon consequently stops half-way. We
must also remember that the cohort concept, as well as chronological
age, serves as a proxy measure for attitudes and behaviours that
actually carry the effect and provide theoretically meaningful
interpretation.
ANNUAL METALWORKING AND MANUFACTURING EXHIBITION AND CONFERENCE ... WESTEC'97
Authors: Esrom K. J.
Published: July 2002

The WESTEC exhibition, held on March 24–27, 1997, at the Los Angeles Convention Center attracted 683 exhibitors and nearly 30,000 manufacturing professionals, the biggest ever event. A wide selection of manufacturing equipment and technologies was displayed in an area of over 250,000 square feet, including machine tools of every description, plastics and integrated design and manufacturing . . . . Over 1000 international equipment lines were exhibited by leading international machine tool builders, and the technology categories included machining, milling, grinding and deburring, cutting tools, drilling and tapping, CAD/CAM, EDM, machine control finishing, laser systems, etc . . . .
Mobile robot society for distributed operations in closed aquatic environment
Authors: Vainio M. , Appelqvist P. , Halme A.
Published: July 2002

In this paper a multirobot system consisting of small size ball-shaped mobile underwater robots is introduced. Robots form a cooperative society operating together for a common goal. This is made possible by inter-member communication and control architecture allowing cooperation. The test environment is a closed aquatic process containing tanks, pipes, and a jet pump. The task considered is cleaning of biologically contaminated spots in the process. Detailed hardware structure of a robot-member as well as the control architecture are introduced. Behaviour of the cooperative system is demonstrated in a test environment where contamination caused by biological algae growth is emulated by infrared panels behaving like a living biomass.
HEALTH TECHNOLOGY ASSESSMENT IN PORTUGAL
Authors: Pinto Manuela Mota , Ramos Francisco , Pereira João
Published: July 2002

The Portuguese healthcare system is often portrayed as a National

Health Service (NHS) model, characterized by universal coverage,

comprehensive benefits, nearly free services, national tax financing, and

public ownership or control of the factors of production. However, in

reality the system fails to accomplish these features in a complete

way. There coexist a number of occupation-related health

insurance schemes that were originally intended to be integrated into

the NHS. In addition, in key areas the NHS does not provide the wide

range of services it promises. The public sector has a predominant

role in the provision of hospital stays and general practitioner

consultations, but the private sector provides a major portion of

specialist consultations, dental consultations, and diagnostic

services. Major problems in the system led to health reforms in the

1990s. New reform proposals include some specific steps concerning

health technology, including standards for medical equipment based on

quality, geographic distribution, sustainability, and

cost-effectiveness. A new National Plan of Health Equipment was

completed in 1998, aimed at improving the distribution of equipment.

Despite reforms, healthcare expenditures continue to rise. There is

general agreement that gains in efficiency could be made. This

situation is beginning to encourage interest in health

technology assessment (HTA) in Portugal, although these activities

are not yet very developed. Recently, legislation requiring

presentation of economic evaluations for new pharmaceutical products

was enacted. Present plans also call for the creation in the future of a national

agency for HTA.
STRONG CONSISTENCY OF ESTIMATORS FOR MULTIVARIATE ARCH MODELS
Authors: Jeantheau Thierry
Published: July 2002

This paper deals with the asymptotic properties
of quasi-maximum likelihood estimators for multivariate
heteroskedastic models. For a general model, we give conditions
under which strong consistency can be obtained; unlike
in the current literature, the assumptions on the existence
of moments of the error term are weak, and no study of
the various derivatives of the likelihood is required.
Then, for a particular model, the multivariate GARCH model
with constant correlation, we describe the set of parameters
where these conditions hold.
OPTIMALITY FOR THE INTEGRATED CONDITIONAL MOMENT TEST
Authors: Boning Wm. Brent , Sowell Fallaw
Published: July 2002

This paper proposes a version of the integrated
conditional moment (ICM) test that is optimal for a class
of composite alternatives. The ICM test is built on the
fact that a random function based on a correctly specified
model should have zero mean, whereas any misspecification
in the conditional mean implies a divergent mean for the
random function. We derive test statistics that are optimal
for each basis element of an orthonormal decomposition
of the function space for which the random function is
an element. We then use a weighted summation of these test
statistics to compose the single test statistic that is
optimal for any pair of alternatives that are symmetric
about zero. This test is equivalent to using a particular
measure in the ICM test of Bierens and Ploberger (1997,
Econometrica 65, 1129–1152).
Prey use among sympatric lizard species in lowland rain forest of Nicaragua
Authors: Vitt Laurie J. , Zani Peter A.
Published: July 2002

The diets of 17 lizard species (seven families) studied simultaneously in a Caribbean lowland forest of Nicaragua were compared. Lizards varied in body size over nearly one order of magnitude. Twelve species for which there were adequate samples separated by prey types and most diet overlaps were low. A pseudocommunity analysis on volumetric diet data revealed significant guild structure in the assemblage. At each nearest neighbour rank in niche space, observed overlaps were higher than expected based on chance alone when all values in the consumer-resource matrix were randomized. There was no difference between observed and pseudocommunity overlaps with zero positions in the consumer-resource matrix retained (conserved-zero overlaps) indicating that the zero structure of the community matrix was important in maintaining structure and that lizards were converging on key resources. Individual prey size varied among species and mean prey size was significantly correlated with body size of lizard species. A phylogenetic analysis revealed no relationship between similarity in prey use (dietary overlap) and evolutionary relationships — more closely related species did not eat more similar prey types. Based on this analysis of Nicaraguan lizard diets and comparisons with other New World tropical lizard assemblages, it is suggested that factors contributing to the organization of tropical lizard assemblages are complex including historical differences in morphology (size), prey types and sizes, habitat structure and species interactions.
Emergence from what? Comments on Sabbagh & Gelman
Authors: MACWHINNEY BRIAN
Published: July 2002

Sabbagh & Gelman (S&G) present an insightful criticism of the emergentist
approach to language acquisition. The analysis takes as its starting point an
expressed frustration with the fact that emergentism is not packaged as a
single theory or formalism. As a result, S&G decide to focus their critical
attention on a particularly strong version of emergentism in which, ‘only
domain-general tools are required to account for language development.’
This strong formulation of the emergentist position matches up well with the
disembodied connectionism of the 1980s (Rumelhart & McClelland, 1986).
However, it misrepresents the richer expressions of emergentism being
developed by the authors of this volume. In particular, this ‘strong’ version
fails to properly appreciate the degree to which emergentists view cognition
as grounded on the body, the brain, and the social situation.

Consider a simple example from phonological development. There is a
universal tendency to avoid sequences of nasal consonants followed by
voiceless obstruents, as might arise in forms like ‘manpower.’ This constraint
is grounded on the facts of speech production (Huffman, 1993) and figures
prominently in recent elaborations of Optimality Theory (Kager, 1999).
Languages use at least five phonological processes to deal with this problem.
These processes include nasal substitution, post-nasal voicing,
denasalization, nasal deletion, and vowel epenthesis. Initially, children may
apply a variety of these processes (Bernhardt & Stemberger, 1998). Which
processes are preserved and which are dropped out will depend on the shape
of the target language, whether it be Indonesian, Quechua, Toba Batak,
English, or Kelantan Malay. In the terms used by S&G, each of these
phonological processes is a small emergentist ‘buzzsaw’ cutting patterns that
are shaped not by some innate cognitive ‘blueprint,’ but by the emergent
facts of articulatory phonology.
A review of methods for the assessment of prediction errors in conservation presence/absence models
Authors: FIELDING Alan H. , BELL JOHN F.
Published: July 2002

Predicting the distribution of endangered species from habitat data is frequently perceived to be a useful technique. Models that predict the presence or absence of a species are normally judged by the number of prediction errors. These may be of two types: false positives and false negatives. Many of the prediction errors can be traced to ecological processes such as unsaturated habitat and species interactions. Consequently, if prediction errors are not placed in an ecological context the results of the model may be misleading. The simplest, and most widely used, measure of prediction accuracy is the number of correctly classified cases. There are other measures of prediction success that may be more appropriate. Strategies for assessing the causes and costs of these errors are discussed. A range of techniques for measuring error in presence/absence models, including some that are seldom used by ecologists (e.g. ROC plots and cost matrices), are described. A new approach to estimating prediction error, which is based on the spatial characteristics of the errors, is proposed. Thirteen recommendations are made to enable the objective selection of an error assessment technique for ecological presence/absence models.
Conservation status of forests and wildlife in the Eastern Ghats, India
Authors: RAWAT GOPAL S.
Published: July 2002

The Eastern Ghats (EGs) comprise a chain of ancient low hills in the state of Andhra Pradesh adjoining the east coast of India. These hill ranges are well known for a rich array of tropical forests with great conservation significance which support large human populations. A series of protected areas (PAs) have been established by the government along these ranges to conserve the regional biodiversity, but their effectiveness is often questionable. In order to assess the ecological status of the forests both within and outside the PAs and to assess the impacts of ongoing forestry practices a survey was conducted along the EGs. Plant species richness, and density of shrubs and trees, were estimated along disturbance gradients (core, buffer and fringe situations) using random plots of 10-m radius for trees, and 5-m radius (nested) plots for shrubs and saplings. Indirect evidence (spoor) of domestic and wild animals was recorded within the sample plots to compare habitat use by the animals.

Srivenkateshwara National Park in the Seshachalam Hills, Gundlabrahmeshwaram Sanctuary in Nallamalais and some parts of Srisailam-Nagarjunasagar Tiger Reserve, had the least degraded forests due to their PA status. However, collection of non-timber forest products, bamboo harvesting and livestock grazing continues in all areas irrespective of legal status. All bamboo areas have been heavily worked. It is recommended that bamboo working should be stopped in core areas of the PAs and reduced from nine to six months (October to March) in the buffer zones. Summer is a period of potential water shortage for wild animals and bamboo workers' camps near water courses may affect habitat use by these species.

The proposed Gudem Maripakhala Sanctuary, well known for its biogeographical value and diverse flora, is seriously threatened as a result of to extensive 'podu' (slash and burn) cultivation. It is suggested that an integrated approach to biodiversity conservation and better agricultural practices, should be adopted in this area. Some of the primary and old growth forests should be identified, mapped and given immediate protection, until a scientifically-based management plan is developed.
Mechanical transmission of lumpy skin disease virus by Aedes aegypti (Diptera: Culicidae)
Authors: CHIHOTA C. M. , RENNIE L. F. , KITCHING R. P. , MELLOR P. S.
Published: July 2002

Aedes aegypti female mosquitoes are capable of the mechanical transmission of lumpy skin disease virus (LSDV) from infected to susceptible cattle. Mosquitoes that had fed upon lesions of LSDV-infected cattle were able to transmit virus to susceptible cattle over a period of 2–6 days post-infective feeding. Virus was isolated from the recipient animals in 5 out of 7 cases. The clinical disease recorded in the animals exposed to infected mosquitoes was generally of a mild nature, with only one case being moderate. LSDV has long been suspected to be insect transmitted, but these findings are the first to demonstrate this unequivocally, and they suggest that mosquito species are competent vectors.
Vaccine effectiveness for influenza in the elderly in welfare nursing homes during an influenza A (H3N2) epidemic
Authors: DEGUCHI Y. , TAKASUGI Y. , NISHIMURA K.
Published: July 2002

Influenza vaccine effect on the occurrence and severity of influenza virus infection in a
population residing in nursing homes for the elderly was studied as a cohort study during an
influenza A (H3N2) epidemic in Japan. Of 22462 individuals living in 301 welfare nursing
homes, 10739 voluntarily received inactivated, sub-unit trivalent influenza vaccine in a
programme supported by the Osaka Prefectural Government. There were statistically
significantly fewer cases of influenza, hospital admissions due to severe infection, and deaths
due to influenza in the vaccinated cohort compared to the unvaccinated controls. No serious
adverse reactions to vaccination were recorded. Thus influenza vaccination is effective for
preventing influenza disease in persons aged 65 years and over, and should be an integral part
of the care of this population residing in nursing homes.
Risk factors for human brucellosis in Yemen: a case control study
Authors: AL-SHAMAHY H. A. , WHITTY C. J. M. , WRIGHT S. G.
Published: July 2002

Brucellosis is known to occur in Yemen but its epidemiology has not been extensively studied.
The present investigation examined risk factors for human brucellosis in Yemen using a
hospital-based case-control study. A total of 235 consecutive patients with brucellosis attending
the Central Health Laboratory in Sana’a, Yemen, were matched in respect of age, sex, and
place of residence, rural or urban, with 234 controls selected from individuals attending the
Central Health Laboratory for unrelated health problems. Clinical information on patients and
controls was supplemented with occupational and socio-economic data obtained by interview
of cases and controls using a standard questionnaire.

After controlling for confounding factors significant risk factors for infection related to
occupation as a farmer (OR 2·5 (95% CI 1·4–4·5, P < 0·0001)),
shepherd (OR 7·8 (95% CI 1·0–61, P 0·05)) or microbiologist
(OR 24·5 (95% CI 2·9–204, P 0·003)); and drinking fresh
milk (OR 2·0 (95% CI 1·3–4·3, P 0·001)) and laban
(OR 22·7 (95% CI 1·7–4·2 P < 0·0001)).
Taking other milk products and offal were not risk factors. Socio-economic and educational
factors were also independent risk factors. Occupational, food and socio-economic risk factors
significantly confounded one another.

Yemen shares some but not all of the risk factors of neighbouring countries. The interrelation
between the various factors is complex and studying any one in isolation may give a
false impression of its public health significance. Control through education of the population
to minimize exposure to, and contact with, animals and their milk and milk products and to
boil milk before drinking it or using it to make buttermilk, would be difficult as these would
represent such fundamental changes to established patterns of behaviour of this society. Ideally
there would be a campaign to control the infection by animal vaccination but the costs and
logistic difficulty would be great. Presently there is a clear need for doctors in Yemen to be
made aware of the frequency of this infection, the means available for clinical and laboratory
diagnosis and effective treatment, while strategies to control the disease in Yemen are
formulated and field tested.
Organization of brain stem afferents to the ventral lateral
geniculate nucleus of rats
Authors: KOLMAC CHRISTIAN , MITROFANIS JOHN
Published: July 2002

We have examined the patterns of projections from
different nuclei of the brain stem to the ventral lateral
geniculate nucleus (vLGN) of the thalamus. Injections of
biotinylated dextran were made into different nuclei of
the brainstem (i.e., midbrain reticular nucleus, pontine
reticular nucleus, deep layers of superior colliculus,
periaqueductal grey matter [ventrolateral, dorsolateral,
and lateral columns], pedunculopontine tegmental nucleus,
parabrachial nucleus, lateral dorsal tegmental nucleus,
substantia nigra [pars reticulata], locus coeruleus,
and dorsal raphe) of Sprague-Dawley rats using stereotaxic
coordinates. Our results show that all of the abovementioned
brain-stem nuclei have overlapping projections to the medial
regions of the vLGN, within the parvocellular lamina of
the nucleus. This if the first instance of the parvocellular
lamina being shown to receive a major set of projections.
Very few labelled terminals from the brain stem were ever
seen within the larger more lateral magnocellular lamina,
which has been shown by previous studies to receive heavy
inputs from visually associated structures, such as the
retina and occipital cortex. Since many of the brain-stem
nuclei injected in this study have little to do with visual
processing, our results suggest that one can perhaps package
the vLGN into distinct visual (magnocellular) and nonvisual
(parvocellular) components.
The role of early retinal lateral inhibition: More than
maximizing luminance information
Authors: BALBOA ROSARIO M. , GRZYWACZ NORBERTO M.
Published: July 2002

Lateral inhibition is one of the first and most
important stages of visual processing. There are at least
four theories related to information theory in the literature
for the role of early retinal lateral inhibition. They
are based on the spatial redundancy in natural images and
the advantage of removing this redundancy from the visual
code. Here, we contrast these theories with data from the
retina's outer plexiform layer. The horizontal cells'
lateral-inhibition extent displays a bell-shape behavior
as function of background luminance, whereas all the theories
show a fall as luminance increases. It is remarkable that
different theories predict the same luminance behavior,
explaining “half” of the biological data. We
argue that the main reason is how these theories deal with
photon-absorption noise. At dim light levels, for which
this noise is relatively large, large receptive fields
would increase the signal-to-noise ratio through averaging.
Unfortunately, such an increase at low luminance levels
may smooth out basic visual information of natural images.
To explain the biological behavior, we describe an alternate
hypothesis, which proposes that the role of early visual
lateral inhibition is to deal with noise without missing
relevant clues from the visual world, most prominently,
the occlusion boundaries between objects.
The rhodopsin cycle is preserved in IRBP “knockout”
mice despite abnormalities in retinal structure and function
Authors: RIPPS HARRIS , PEACHEY NEAL S. , XU XIAOPING , NOZELL SUSAN E. , SMITH SYLVIA B. , LIOU GREGORY I.
Published: July 2002

In the vertebrate retina, vision is initiated and
maintained by the photolysis and regeneration, respectively,
of light-sensitive pigments in the disk membranes of the
photoreceptor outer segments. This cyclical process depends
on an exchange of retinoids between the photoreceptors
and the retinal pigment epithelium (RPE). There is a great
deal of indirect evidence that the transport of retinoids
between these cellular compartments is mediated by the
interphotoreceptor retinoid-binding protein (IRBP), a large
glycoprotein synthesized in the photoreceptors and extruded
into the interphotoreceptor matrix (IPM) that fills the
subretinal space. Nevertheless, a number of in vitro
experiments have demonstrated that an intermembranous transfer
of retinoids can occur through an aqueous medium independent
of any retinoid-binding protein. This led to the suggestion
that IRBP may play the more passive role of an extracellular
buffer, serving to prevent the degradation and potentially
cytotoxic effects of free retinoids when large amounts
are released into the IPM. We have studied the structural
and functional properties of transgenic mice in which homologous
recombination was used to delete the IRBP gene. Light-
and electron-microscopic examination of the retinas of
“knockout” (IRBP−/−) mice
revealed a significant loss of photoreceptor nuclei, and
profound changes in the structure and organization of the
receptor outer segments. Consistent with these observations,
electroretinographic recordings showed a marked reduction
in response amplitude for both rod- and cone-mediated potentials.
However, despite the histological and electrophysiological
changes, there was no evidence of gross abnormalities in
the visual cycle. After bleaching a significant fraction
of the available rhodopsin, electroretinogram amplitude
and rhodopsin density gradually increased toward their
pre-bleach levels, and the rates of recovery were even
more rapid than those seen in wild-type (IRBP+/+)
mice.