bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the stability of large-amplitude vortices in a
continuously stratified fluid on the f-plane
Authors: BENILOV E. S. , BROUTMAN D. , KUZNETSOVA E. P. 
Published: July 2002

The stability of continuously stratified vortices
with large displacement of isopycnal
surfaces on the f-plane is examined both
analytically and numerically. Using an
appropriate asymptotic set of equations, we demonstrated that
sufficiently large
vortices (i.e. those with small values of the Rossby number)
are unstable. Remarkably,
the growth rate of the unstable disturbance is a function of
the spatial coordinates. At
the same time, the corresponding boundary-value problem for
normal modes has no
smooth square-integrable solutions, which would normally
be regarded as stability.We conclude that (potentially) stable vortices can be
found only among ageostrophic
vortices. Since this assumption cannot be verified
analytically due to complexity of the
primitive equations, we verify it numerically for the
particular case of two-layer stratification.
Aeroacoustic properties of supersonic elliptic jets
Authors: KINZIE KEVIN W. , McLAUGHLIN DENNIS K. 
Published: July 2002

The aerodynamic and acoustic properties of supersonic elliptic and circular jets
are experimentally investigated. The jets are perfectly expanded with an exit Mach
number of approximately 1.5 and are operated in the Reynolds number range of
25 000 to 50 000. The reduced Reynolds number facilitates the use of conventional
hot-wire anemometry and a glow discharge excitation technique which preferentially
excites the varicose or flapping modes in the jets. In order to simulate the high-velocity
and low-density effects of heated jets, helium is mixed with the air jets. This allows
the large-scale structures in the jet shear layer to achieve a high enough convective
velocity to radiate noise through the Mach wave emission process.Experiments in the present work focus on comparisons between the cold and
simulated heated jet conditions and on the beneficial aeroacoustic properties of the
elliptic jet. When helium is added to the jet, the instability wave phase velocity is
found to approach or exceed the ambient sound speed. The radiated noise is also
louder and directed at a higher angle from the jet axis. In addition, near-field hot-wire spectra are found to match the far-field acoustic spectra only for the helium/air
mixture case. These results demonstrate that there are significant differences between
unheated and heated asymmetric jets in the Mach 1.5 speed range, many of which
have been found previously for circular jets. The elliptic jet was also found to radiate
less noise than the round jet at comparable operating conditions.
Self-similarity, momentum scaling and Reynolds stress in
non-premixed turbulent spray flames
Authors: KARPETIS A. N. , GOMEZ A. 
Published: July 2002

An experimental study was conducted in a turbulent spray flame in which droplets
were produced ultrasonically at low velocity relative to the host gas. In this fashion,
injector-specific effects on the two-phase flow were minimized and a scenario generally
characteristic of the far field of practical spray systems could be simulated. Close to
the burner exit, the spray flame appeared as a dense column of drops burning with
an envelope flame. Further downstream, it opened up slowly in the radial direction
and developed a turbulent ‘brush’ appearance. Measurements of the size, velocity
and concentration of the droplets, and of gas-phase velocity and temperature were
made by combining a Phase-Doppler interferometric technique with Stokes/anti-Stokes Raman thermometry. The experimental data were used to derive scaling and
self-similarity for the Reynolds-averaged continuity and momentum equations using
suitable transformations.Results showed three distinct regions, on the basis of the behaviour of the gas
axial velocity in the spray flame. In the lower part of the flame, the gas momentum
increased because of vaporization. In the intermediate region of the spray flame,
the axial velocity decayed along the centreline as an inverse power of the distance
from the virtual origin, with exponents smaller than unity. In the upper part of
the spray flame, the flow field recovered the axial velocity decay that is typical of
incompressible jets, namely as an inverse of the axial distance. Self-similar behaviour
held for the axial velocity throughout the intermediate region. The vapour source
term in the gas continuity equation scaled approximately as an inverse power of
axial distance, and exhibited self-similarity throughout the spray flame. As a result,
a simple model of the Reynolds stress term could be formulated, in which two
competing contributions appear: one, that is due to turbulent transport, tends to
increase the value of the velocity correlation; another, that is due to the vaporization
term, tends to reduce the value of the velocity correlation and can be construed as a
vaporization-induced tendency towards relaminarization. The first term is modelled
by a classic gradient-transport approach yielding an empirical mixing length relating
the velocity correlation to the average velocity gradient. Model and experiments are
found to be in good agreement, especially sufficiently far from the injector, where
one-way coupling between the two phases holds.
The flickering candle: transition to a global oscillation in a thermal plume - Corrigendum
Authors: Maxworthy T. 
Published: July 2002

The flickering candle: transition to a global oscillation
in a thermal plumeJournal of Fluid Mechanics, vol. 390 (1999), pp. 297–323On page 302, the fourth and third lines from the bottom of the page, for the word
‘important’ read ‘unimportant’.
The 12-month prevalence and characteristics of major depressive episode in a representative nationwide sample of adolescents and young adults
Authors: HAARASILTA L. , MARTTUNEN M. , KAPRIO J. , ARO H. 
Published: July 2002

Background. This study set out to estimate the 12-month prevalence of DSM-III-R major depressive episode (MDE) and to analyse factors associating with psychosocial impairment, episode duration, phenomenology and symptom severity in a representative general population sample of adolescents (15–19-year-olds) and young adults (20–24-year-olds).Method. The Finnish Health Care Survey '96 (FINHCS '96) was a cross-sectional nationwide epidemiological study. A random sample of 509 adolescents and 433 young adults was interviewed in 1996. MDE was assessed by University of Michigan Composite Diagnostic Interview Short-Form.Results. The 12-month prevalence of MDE was 5·3% for adolescents (females 6·0%, males 4·4%) and 9·4% for young adults (females 10·7%, males 8·1%). When moderate psychosocial impairment was included in case definition, the prevalences were lowered by 20–25%. Increased impairment was associated with drunkenness at least twice a month, a higher mean number of depressive symptoms and impaired concentration. The median episode duration was 1 month. No factors associating with duration were found. With the exception of symptoms related to appetite being more common among females than males, the phenomenology of MDE was mainly independent of age and gender.Conclusions. Episodes of major depression among adolescents and young adults in the general population are short but often associated with psychosocial impairment, especially if frequent drunkenness coexists.
Morphometry in schizophrenia revisited: height and
its relationship to pre-morbid function
Authors: NOPOULOS P. , FLAUM M. , ARNDT S. , ANDREASEN N. 
Published: July 2002

Background. Morphometry, the measurement of forms, is
an
ancient practice. In particular,
schizophrenic somatology was popular early in this century, but has
been essentially absent from
the literature for over 30 years. More recently, evidence has grown to
support the notion that
aberrant neurodevelopment may play a role in the pathophysiology of schizophrenia.
Is the body,
like the brain, affected by abnormal development in these patients?Methods. To evaluate global deficit in development and
its relationship to pre-morbid function,
height was compared in a large group (N=226) of male
schizophrenics and a group of healthy male
controls (N=142) equivalent in parental socio-economic status.
Patients
in the lower quartile of
height were compared to those in the upper quartile of height.Results. The patient group had a mean height of 177·1
cm,
which was significantly shorter than the
mean height of the control group of 179·4 (P<0·003).

Those in the lower quartile had significantly
poorer pre-morbid function as measured by: (1) psychosocial adjustment
using the pre-morbid
adjustment scales for childhood and adolescence/young adulthood, and

(2) cognitive function using
measures of school performance such as grades and need for special
education. In addition, these
measures of pre-morbid function correlated significantly with height
when analysed using the entire sample.Conclusions. These findings provide further support to the

idea that abnormal development may
play a key role in the pathophysiology of schizophrenia. Furthermore, this
is manifested as a
global deficit in growth and function resulting in smaller stature,
poorer social skills, and deficits in cognitive abilities.
Abnormal response to negative feedback in
depression
Authors: SHAH P. J. , O'CARROLL R. E. , ROGERS A. , MOFFOOT A. P. R. , EBMEIER K. P. 
Published: July 2002

Background. Recent studies have suggested that subjects
with depression suffer a diagnosis-specific
motivational deficit, characterized by an abnormal response to negative
feedback that endures
beyond clinical recovery. Furthermore, it has been suggested that negative
feedback may motivate
non-depressed controls, but not depressed patients, to improve their performance
in neuropsychological tests.Methods. We describe two studies. The first compared performance
on the simultaneous and
delayed match to sample (SDMS) task from the CANTAB neuropsychological
test battery, in 20
patients with severe depression with 20 with acute schizophrenia, 40 with
chronic schizophrenia and
40 healthy controls. The second examined the performance of depressed patients
with diurnal
variation in symptoms and cognitive function.Results. All patients groups showed impairments on the simultaneous
and delayed match to sample
task compared to controls. Depressed patients did not show an abnormal
response to negative
feedback. Controls did not show a motivational effect of negative feedback.
Depressed patients with
diurnal variation showed no variation in their response to perceived failure.
There was no evidence
of abnormal response to negative feedback in any patient group using the
‘runs test’ or of a
motivational effect in controls. Conditional probability analysis was not
independent of the total
number of errors made in the SDMS task.Conclusions. Further studies are suggested to examine whether
an abnormal response to negative
feedback characterizes particular subgroups of patients suffering from
depression.
Why are patients prescribed psychotropic drugs by general practitioners? Results of an international study
Authors: KISELY S. , LINDEN M. , BELLANTUONO C. , SIMON G. , JONES J. 
Published: July 2002

Background. There has been growing interest in factors that might influence the prescription of psychotropic drugs in general practice.Method. This was a multi-centre study using a two-phase stratified sampling strategy in primary care facilities from 14 different countries to determine factors associated with the prescription of psychotropic drugs.Results. A total of 1763 consecutive GP attenders aged between 16 and 65 years of age were recruited. Although antidepressants were used more for depressive disorders and anxiolytics for patients with anxiety, the differential diagnosis was otherwise not an important factor in prescribing behaviour. Antidepressants and anxiolytics were prescribed twice as frequently in client centred
clinics following a ‘personal physician model’ as opposed to non-client centred settings, where care was less personalized. The reverse was true of hypnotics (adjusted odds ratio of 0·5). General practitioners with a positive view of their undergraduate psychiatric training and who had had further postgraduate experience in the speciality were significantly less likely to prescribe medication, and if they did they were more likely to use antidepressants. Older patients were significantly more likely to be prescribed psychotropic medication. Several other patient factors emerged when individual classes of medication were considered; these included the loss of a spouse and the absence of physical ill health in the case of antidepressants, and female sex, fewer years of schooling and unemployment in the case of anxiolytics.Conclusions. Social, health care and GP factors are at least as important as clinical features in the prescription and choice of psychotropic medication.
Negative existentials, omniscience, and cosmic luck
Authors: Hughes Christopher 
Published: July 2002

Suppose there are possible worlds in which God exists but Anselm
does
not. Then (I argue) there are possible worlds in which Anselm does not
exist, but
God cannot even entertain the thought that he does not. In such worlds
Anselm does
not exist, but God does not know that. This, I argue, is incompatible with
(a
straightforward construal of) the doctrine of God's essential omniscience.
Considerations
involving negative existentials also call into question a certain picture
of
creation, on which God chooses which particular (possible) individuals
to create.
They suggest that there is an element of brute contingency about which
individuals
exist.Mediaeval philosophical theologians held – so far as I know without
exception –
that God was essentially omniscient. In what follows, I shall argue
that the existence of individuals whose non-existence is compossible with

God's existence raises serious difficulties for the doctrine of God's
essential
omniscience. If there are individuals that might not have existed even
though
God did, then – I shall try to show – questions arise about
whether God
would have been omniscient, if He had existed, but they hadn't.
Is there such a thing as the ‘blue note’?
Authors: WEISETHAUNET HANS 
Published: July 2002

Among the most frequently repeated formulae in the description of the traditions most often called Afro-American
music, in particular the styles of jazz, blues, soul and rock, is the concept of the `blue note’. It may also seem that
this is a most widely accepted idea. The ‘blue note’ is usually thought of as a kind of basic element in those styles,
as constituting the `ethnic’ or ‘African’ aspect of those musics as opposed to the ‘Western’ contributions of harmony.My main attempt here is to step into the somewhat muddy waters of musicological and sociological/anthropoligical/
cultural studies discourses of ‘the blue’ and ask what the ‘blue idea’ really is about. In rethinking the concept of the
‘blue note’, I find it necessary to differentiate between two concerns that often seem to be somewhat unconsciously
or muddily mixed together:(1) the idea of the ‘blue note’ as referring to pitch, thinking of the note as an ‘item’, commonly thought of as the
slight altering of the minor third and the flattened seventh; and(2) the general concept of `blue feeling’ linked to the idea of playing ‘blue notes’: in short, the performance of music
with a ‘blue feel’.
Chain recurrence in flows on the Klein bottle
Authors: ALEXELLIS ATHANASSIOS , ATHANASSOPOULOS KONSTANTIN 
Published: July 2002

In the classical Poincaré–Bendixson theory
the object of study are the limit sets of a continuous flow on the 2-sphere
S2 and the behaviour of the orbits near them
(see [7, 9]). In [2] the
second author proved that an assertion similar to the Poincaré–Bendixson
theorem is true in the wider class of the 1-dimensional invariant (internally)
chain recurrent continua of flows on S2. On the other
hand, it is known that among the closed 2-manifolds, the 2-sphere S2,
the projective plane RP2 and the
Klein bottle K2 are the only ones for which the
Poincaré–Bendixson theorem is true
(see [1, 8, 11]).The motivation of the present paper was to examine to what extent the main
results of [2] carry over to flows on RP2
and K2. A first attempt to study chain
recurrent sets of flows on closed 2-manifolds other than the 2-sphere
was [3]. As one
expects, the results of [2] carry over easily to
RP2, since chain recurrence behaves
well with respect to regular covering maps of compact manifolds, as we show in
Section 3. The situation with K2 is quite different,
since it is doubly covered by the
2-torus T2, where we have no Poincaré–Bendixson
theorem. Actually, the Poincaré–Bendixson theorem for
1-dimensional invariant chain recurrent continua of flows on
K2 is not true. For example, identifying
suitably the boundary periodic orbits of
a 2-dimensional Reeb flow on a closed annulus (see
[7, chapter III, 2·6]) we get a
flow on K2 with a 1-dimensional invariant chain
recurrent continuum consisting of
the unique periodic orbit and another orbit, which spirals against it in positive and
negative time. As we prove in Theorem 4·4, this situation, or concatenations of it,
is the only one where the Poincaré–Bendixson theorem for 1-dimensional invariant
chain recurrent continua of flows on K2 is not
true. Then, we are concerned with
the topological structure of the 1-dimensional chain components of a flow on
K2 with finitely many singularities. In
Proposition 4·6 we find when such a set consists
of finitely many orbits and is homeomorphic to a finite graph. An example shows
that the hypothesis of Proposition 4·6 is essential. Finally,
in Theorem 4·9 we give a
description of the structure of the 1-dimensional chain components of a
flow on K2 with finitely many singular points.
GPS in Agriculture – A Growing Market!
Authors: Stafford J. V. 
Published: July 2002

This paper, and the paper which follows it, were first presented
at the IBC '98
Conference ‘Space-Based Navigation Industry’, which was held
in London,
11–12 June 1998.In conventional arable agriculture, position within the field was
usually irrelevant! However,
the advent of precision agriculture, wherein inputs are targeted according
to locally-determined requirements within the field, has opened up a potentially large
market for GPS.
Indeed, it was the availability of GPS which permitted the development
and implementation
of precision agriculture – a concept which holds the promise of significant
economic and
environmental benefits to the farmer. This paper indicates the technical
requirements for
GPS and presents three case studies where a positioning system is required.
A comparison of the enforcement of access restrictions between Xishuangbanna Nature Reserve (China) and Khao Yai National Park (Thailand)
Authors: ALBERS HEIDI J. , GRINSPOON ELISABETH 
Published: July 2002

Given limited budgets to enforce access restrictions, protected area (PA) managers and non-governmental organizations (NGOs) in developing countries employ a range of policy instruments to conserve the area's natural resources. Natural characteristics of the PA combine with the managers' enforcement activities and other policy instruments to create a set of incentives to which local people respond in making decisions about extracting resources from the PA. The different management approaches employed in the Xishuangbanna Nature Reserve (XNR; China) and the Khao Yai National Park (KYNP; Thailand) and the reaction to the incentives which they create are compared. KYNP managers use policing and punishment mechanisms, in conjunction with limited NGO-supported income-generation projects, to deter resource use. In contrast, XNR managers rely on extensive cooperation with local people and trade-offs between current resource degradation and increased rural incomes.As predicted by the economic enforcement literature, rural people respond to the threat of punishment, and its reduction of the expected benefit of an illegal activity, by reducing that activity, but may undertake socially-costly avoidance activities to avoid punishment. This literature also correctly predicts that XNR managers will concentrate less on pure enforcement than KYNP managers because, as a result of a difference in government mandates, the XNR managers consider the value of the extracted products and the non-PA productivity in their decisions while the KYNP managers do not. In both PAs, rural people's actions affect the quality of resource conservation. In KYNP, natural characteristics and the policing activities deter resource extraction and encroachment in the central core of the Park. Even NGO projects, however, have not controlled extraction, and even agricultural encroachment, in the outer third of the Park, which has caused over-extraction of some resources and has left a ring of highly-degraded land. In contrast, XNR's cooperative management approach has generated more control over the amount and the spatial configuration of resource degradation. XNR's control, however, comes at the cost of reduced area and level of current conservation.
Spatial organization, ranging behaviour and habitat use of the kodkod (Oncifelis guigna) in southern Chile
Authors: Dunstone Nigel , Durbin Leon , Wyllie Ian , Freer Rachel , Jamett Gerardo Acosta , Mazzolli Marcelo , Rose Sam 
Published: July 2002

AbstractThe kodkod Oncifelis guigna has one of the smallest distributions of wild felids, being geographically restricted to a narrow strip within Chile and Argentina. An investigation of population demography and habitat selection was carried out using trapping and radio‐telemetry techniques in transitional Valdivian forest at two sites in southern Chile. The mean home‐range size was estimated at 269 ha with considerable overlap of ranges and core areas giving a density of combined adults and sub‐adults of 0.97/km2. Forest, thicket‐forest, and scrub‐thicket predominated in the ranges of most individuals and habitats at less than 50 m elevation were more frequently used than higher slopes. With the exception of páramo and thicket, all other habitat types were used more frequently than expected by at least one of the kodkods. The study confirmed the strong habitat association with Valdivian and Araucaria forests previously reported for this species, but also suggested a more flexible use of habitat within home ranges and individual preferences of habitat used as core areas. Flexibility in resource use and mutual avoidance may explain why kodkod ranges overlap and populations reach high densities locally. This high degree of adaptability may well be relevant to the long‐term survival of this species in an ever increasing, anthropogenically‐modified environment.
Wave solutions for a discrete reaction-diffusion
equation
Authors: CARPIO A. , CHAPMAN S. J. , HASTINGS S. , McLEOD J. B. 
Published: July 2002

Motivated by models from fracture mechanics and from biology, we study the infinite system of differential equationsformula herewhere A and F are positive parameters. For fixed A > 0 we show that there are monotone travelling waves for F in an interval Fcrit < F < A, and we are able to give a rigorous upper
bound for Fcrit, in contrast to previous work on similar problems. We raise the problem of
characterizing those nonlinearities (apparently the more common) for which Fcrit > 0. We
show that, for the sine nonlinearity, this is true if A > 2. (Our method yields better estimates
than this, but does not include all A > 0.) We also consider the existence and multiplicity of
time independent solutions when |F|< Fcrit.