bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformal measure and decay of correlation for covering weighted systems
Authors: LIVERANI CARLANGELO , SAUSSOL BENOIT , VAIENTI SANDRO
Published: July 2002

We show that for a large class of piecewise monotonic transformations on a totally ordered, compact set one can construct conformal measures and obtain the exponential mixing rate for the associated equilibrium state. The method is based on the study of the Perron–Frobenius operator. The conformal measure, the density of the invariant measure and the rate of mixing are deduced by using an appropriate Hilbert metric, without any compactness arguments, even in the case of a countable to one transformation.
Angular distributions of ions from laser-produced plasma
Authors: WORYNA E. , PARYS P. , WOŁOWSKI J. , KRÁSA J. , LÁSKA L. , KRÁLIKOVÁ B. , PFEIFER M. , ROHLENA K. , SKÁLA J.
Published: July 2002

This paper presents comprehensive experimental
results of angular distributions of ions emitted from laser-produced
plasmas. Performing a series of laser shots onto planar
Sn, Au, and Pb targets, both the focusing conditions as
well as the tilt angle of the target were changed to study
the effect on the plasma expansion. In the experiments,
the iodine laser system PERUN (laser energy of 30 J in
350 ps of duration) with laser power density of 5 ×
1014 W/cm2 was used. For plasma diagnostics
four ion collectors and an ion-energy analyzer were applied.
Comparison of angular distribution of the fast ion group
(velocity within the range of 1–3.4 × 108
cm/s) and of the slow ion group (velocity within the range
of 0.14–1 × 108 cm/s) shows distinct
differences. The preferred direction of ion emission of
these groups depends seriously on focusing conditions.
When setting the focus on the in-focus position both groups
of ions are peaked in the direction close to the target
normal. The maximum charge of ions registered by the ion-energy
analyzer were 36+, 51+, and 49+ for Sn, Au, and Pb, respectively.
Optimal tripod turning gait generation for hexapod walking machines
Authors: Miao S. , Howard D.
Published: July 2002

This paper describes an algorithm

for generating a tripod turning gait which, when given an

arbitrarily located turning centre, firstly maximises the rotation angle (angular

stride) and then secondly optimises the stability. It does not

require a specific walking machine layout or leg workspace shape,

and it can deal with changes in the position of

the CG caused by walking on a gradient or by

uneven loading.
Evaluation of influence of target location on robot repeatability
Authors: Riemer Raziel , Edan Yael
Published: July 2002

This paper evaluates the influence of target location on robot repeatability. An experiment was set up to analyze the effect of the three-dimensional target location on robot repeatability. An error-analysis model to determine repeatability based on the robot's kinematic model and known robot parameters was developed. Experimental results indicated that there was a significant statistical difference between repeatability at different

locations in the workspace and that the height of the target point influenced repeatability. Experimental results tended to those derived from the error-analysis kinematic model. Hence, to determine the optimal target location, there is no need for extensive experimentation; instead, only a few target points can be sampled and compared to an error-analysis model.
SECOND-ORDER APPROXIMATION FOR ADAPTIVE REGRESSION ESTIMATORS
Authors: Linton Oliver , Xiao Zhijie
Published: July 2002

We derive asymptotic expansions for semiparametric adaptive
regression estimators. In particular, we derive the asymptotic
distribution of the second-order effect of an adaptive estimator
in a linear regression whose error density is of unknown functional
form. We then show how the choice of smoothing parameters
influences the estimator through higher order terms. A method
of bandwidth selection is defined by minimizing the second-order
mean squared error. We examine both independent and time series
regressors; we also extend our results to a t-statistic.
Monte Carlo simulations confirm the second order theory and
the usefulness of the bandwidth selection method.
The mechanism of general flowering in Dipterocarpaceae in the
Malay Peninsula
Authors: Yasuda Masatoshi , Matsumoto Jun , Osada Noriyuki , Ichikawa San'ei , Kachi Naoki , Tani Makoto , Okuda Toshinori , Furukawa Akio , Nik Abdul Rahim , Manokaran N.
Published: July 2002

The
mechanism of general flowering in Dipterocarpaceae in the Malay
Peninsula is revealed through field survey and meteorological data
analyses. The regions of general flowering coincide with those which
experienced a low night-time temperature (LNT) c. 2 mo before
flowering. This supports the hypothesis that low air temperature induces
the development of floral buds of dipterocarps. LNT was found to be
caused by radiative cooling during dry spells in winter when the
northern subtropical ridge (STR) occasionally migrates southwards with a
dry air mass into the equatorial region. LNT events usually occur in La
Niña episodes, not in El Niño episodes as believed
previously. This is because the southward migration of the STR is
associated with the intensification of local meridional Hadley
Circulation in the western Pacific, which is strengthened in a La
Niña episode. Results suggest that El Niño-like climate
change in increased atmospheric carbon dioxide concentrations may be
critical for the tropical rain forest biome in south-east Asia.
Vector Map Data Compression with Wavelets
Authors: Ioup Juliette W. , Gendron Marlin L. , Lohrenz Maura C.
Published: July 2002

This paper was first presented at a Symposium on ‘Advanced Moving-Map Displays’ held on
the 3rd and 4th of August 1999 by the US Naval Research Laboratory Detachment at the
NASA Stennis Space Centre, Mississippi, and is reproduced in modified form with the kind
permission of the NRL Commanding Officer, Captain Douglas H. Rau USN.

Wavelets and wavelet transforms can be used for vector-map data compression. The
choice of wavelet, the level of decomposition, the method of thresholding, the height of the
threshold, relative CPU times and file sizes, and reconstructed map appearance were
investigated using the Wavelet Toolbox of MATLAB. Quantitative error measures were
obtained. For two test vector-map data sets consisting of longitude and latitude points,
compressions of 35 to 50 percent (1·5[ratio ]1 to 2[ratio ]1) were obtained with root-mean-square errors
less than 0·003 to 0·01° longitude/latitude for wavelet packet decompositions using selected
wavelets.
Trace element concentrations in the tissues of cetaceans from Hong Kong's territorial waters
Authors: PARSONS E.C.M.
Published: July 2002

There have been few studies of trace elements in cetaceans from Chinese waters despite considerable potential for contamination by this class of pollutant. Between 1993 and 1996, blubber, liver and/or kidney tissues were collected from 11 Indo-Pacific hump-backed dolphins (Sousa chinensis) and 20 finless porpoises (Neophocaena phocaenoides) stranded in Hong Kong. These tissues were analysed for 12 trace elements (As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sn and Zn). In general, concentrations of trace elements were similar to those of other cetacean populations and were deemed not to be of any toxicological significance. However, concentrations of mercury in the liver tissues of certain individuals were at levels which could constitute a health risk to the animals (up to 906 mg g-1 dry weight). Cadmium, mercury and selenium were observed to bio-accumulate with age, whereas concentrations of copper were highest in neonatal animals.
Typed feature structures and design space exploration
Authors: WOODBURY R. , BURROW A. , DATTA S. , CHANG T-W.
Published: July 2002

Design space explorers are computer programs that play
on an exploration metaphor to support design.
They assist designers in creating alternative designs by
structuring the process of design creation in a space of
alternatives. Subsidiary metaphors relevant to design space
explorers are generation, navigation,
and reuse. This paper introduces, in two sketches,
typed feature structures as a formal system in which a
design space explorer and its knowledge level might be
implemented. First, informal and abstract properties of
typed feature structures suffice to build a sketch of the
behavior of a design space explorer. Second, using an example
based on single-fronted cottages (a common Australian housing
type), we outline the typed feature structure machinery
most relevant to design space exploration.
Ensemble modelling or selecting the best model: Many could
be better than one
Authors: BARAI S.V. , REICH YORAM
Published: July 2002

In the course of data modelling, many models could be
created. Much work has been done on formulating guidelines
for model selection. However, by and large, these guidelines
are conservative or too specific. Instead of using general
guidelines, models could be selected for a particular task
based on statistical tests. When selecting one model, others
are discarded. Instead of losing potential sources of information,
models could be combined to yield better performance. We
review the basics of model selection and combination and
discuss their differences. Two examples of opportunistic
and principled combinations are presented. The first demonstrates
that mediocre quality models could be combined to yield
significantly better performance. The latter is the main
contribution of the paper; it describes and illustrates
a novel heuristic approach called the SG(k-NN) ensemble
for the generation of good-quality and diverse models that
can even improve excellent quality models.
Surveying vendors of street-vended food: a new methodology
applied in two Guatemalan cities
Authors: MAHON B. E. , SOBEL J. , TOWNES J. M. , MENDOZA C. , GUDIEL LEMUS M. , CANO F. , TAUXE R. V.
Published: July 2002

Lack of reliable data about street vendors, who are difficult to survey, has hampered efforts to
improve the safety of street-vended food. A two-phase method for sampling vendors, surveying
first in areas of concentrated vending activity identified by local authorities and second in
randomly selected areas, was developed and implemented in two Guatemalan cities where
street-vended food had been implicated in cholera transmission. In a 4-day survey in Escuintla,
59 vendors (42 from phase 1, 17 from phase 2) were interviewed. They demonstrated good
knowledge of food safety and cholera but unsafe practices, implying that more effective,
practical training was needed. In a 6-day survey in Guatemala City, 78 vendors (77 from phase
1, 1 from phase 2) were interviewed. Sixty-eight (87%) vendors stored water, usually in wide-mouthed vessels prone to contamination; this led to a field test of a new system for safe water
storage. Useful information for public health planning and intervention can be gathered rapidly
with this new method for surveying street vendors.
Expression of glycine and the glycine transporter Glyt-1
in the developing rat retina
Authors: POW DAVID V. , HENDRICKSON ANITA E.
Published: July 2002

Previous studies show that glycine transporter-1
(glyt-1) is a consistent membrane marker of adult retinal
neurons that are likely to release glycine at their synaptic
terminals (Pow, 1998; Vaney et al., 1998; Pow & Hendrickson,
1999). The current study investigated when glyt-1 immunoreactivity
appeared in the postnatal rat retina, and whether all glycine-containing
neurons also labelled for glyt-1. Ganglion cells, horizontal
cells, and photoreceptors showed transient labelling. Many
cells in the ganglion cell layer are immunoreactive for
both glycine and glyt-1 at postnatal day (Pd) 1 but both
are minimal by Pd5. Transient immunoreactivity for both
glyt-1 and glycine was observed in presumptive horizontal
cells between Pd5 and Pd10. At Pd1 many cells in the outer
part of the retina which resembled immature photoreceptors
were heavily labelled for glycine, but did not express
glyt-1; these disappeared at older ages. These findings
suggest diverse mechanisms and transient roles for glycine
in the developing rat retina. In the adult rat retina,
a subpopulation of amacrine cells are prominently immunoreactive
for both glycine and glyt-1. These cells labelled for glycine
at Pd1, but did not express significant levels of glyt-1
until Pd5. Processes from these amacrine cells did not
reach the inner half of the inner plexiform layer until
Pd10–14. Bipolar cells became glycine-IR between
Pd10 and Pd14, but consistently lacked any glyt-1 immunoreactivity.
This temporal pattern of labelling strongly indicates that
bipolar cells label for glycine when gap junctions become
functional between glycine/glyt-1 immunoreactive amacrine
cells and cone bipolar cells.
GABAA receptor binding and localization in the
tiger salamander retina
Authors: WANG HAO , STANDIFER KELLY M. , SHERRY DAVID M.
Published: July 2002

Gamma-aminobutyric acid (GABA) is the major inhibitory
neurotransmitter in the retina and also appears to act
as a trophic factor regulating photoreceptor development
and regeneration. Although the tiger salamander is a major
model system for the study of retinal circuitry and regeneration,
our understanding of GABA receptors in this species is
almost exclusively based on the results of physiological
studies. Therefore, we have examined the pharmacological
binding properties of GABAA receptors and their
anatomical localization in the tiger salamander retina.
Radioligand-binding studies showed that specific 3H-GABA
binding to GABAA receptors was dominated by
a single high-affinity binding site (Kd
= 15.6 ± 6.9 nM). Specific binding of 3H-GABA
was almost completely eliminated by muscimol
(Ki = 105 ± 62 nM) and
bicuculline (Ki = 14.3 ±
2.2 μM); however, SR-95531 only displaced about 40%
of specific 3H-GABA binding (Ki
= 35.0 ± 3.8 nM). These data indicate that there are at least
two subtypes of GABAA receptors present in the
salamander retina that can be distinguished by their antagonist
binding properties: one sensitive to both bicuculline and SR-95531,
and one sensitive to bicuculline but insensitive to SR-95531.
Because localization of GABA receptors in the salamander retina by
immunocytochemistry is problematic, GABAA receptors were
localized by fluorescent ligand binding combined with immunocytochemical
labeling for cell specific markers. Binding of fluorescently
labeled muscimol to GABAA receptors was present
in both plexiform layers and on photoreceptor cell bodies.
GABAA receptors in the outer plexiform layer
were localized to both photoreceptor terminals and horizontal
cell processes.
Development of glutamate receptor subunit 2 immunoreactivity
in postnatal rat retina
Authors: JOHANSSON KJELL , BRUUN ANITHA , TÖRNGREN MARIE , EHINGER BERNDT
Published: July 2002

Previous studies have shown that the expression of glutamate receptor
subunits is developmentally regulated and have been implicated in
processes of cell differentiation during postnatal life. The tissue
localization and developmental pattern of the glutamate receptor 2 subunit
of the α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA)
receptor were investigated by means of immunohistochemistry and
immunoblotting. Labeling of amacrine and ganglion cells and the inner
plexiform layer appeared early during development, while glutamate
receptor 2 subunit expression in the outer plexiform layer started
after the first postnatal week. The distribution of labeling within
the inner plexiform layer changed from nonorganized to laminated
appearance prior to eye-opening. There was an increasing number of
positive amacrine and ganglion cell somata during the first 2 weeks,
but their number decreased considerably as the retina matured and were
seen at least up to 35 days of postnatal development. Little labeling
was found in the ganglion cell layer and in the inner plexiform layer of
late postnatal and adult retina. Labeling in the outer plexiform layer
and of bipolar cell somata appeared to increase in the developing retina.
Glur2 labeling of these cells and the outer plexiform layer became
discernible during the second postnatal week, and this labeling was
present in the adult as well. Immunoblotting showed that GluR2 protein
levels were similar at postnatal days 7 and 10, but slightly decreased
between the second and fourth postnatal weeks. Our data imply that the
immunological expression of glutamate receptor 2 subunit in the inner
plexiform layer decreases as a function of age, and is correlated with
developmental event(s) in the postnatal retina.
Consistent mapping of orientation preference across irregular
functional domains in ferret visual cortex
Authors: WHITE LEONARD E. , BOSKING WILLIAM H. , FITZPATRICK DAVID
Published: July 2002

The mammalian visual cortex harbors a number of functional
maps that represent distinct attributes of stimuli in the
visual environment. How different functional maps are accommodated
within the same cortical space, especially in species that
show marked irregularities in one or more functional maps,
remains poorly understood. We used optical imaging of intrinsic
signals and electrophysiological techniques to investigate
the organization of the maps of orientation preference,
ocular dominance, and visual space in ferret. This species
shows striking nonuniformity in the arrangement of ocular
dominance domains and disruption of the mapping of visual
space along the V1/V2 border. We asked whether these irregularities
would be reflected in the organization of the map of orientation
preference. The results show that orientation preference
is mapped consistently within both V1 and V2, and across
the interareal boundary, with no reflection of the irregularities
in the other maps. These observations demonstrate the accommodation
of multiple functional maps within the same cortical space
without systematic geometrical relationships that necessarily
constrain the organization of each representation. Furthermore,
they imply that the structure of the map of orientation
preference reflects the architecture and activity patterns
of cortical circuits that are independent of other columnar
systems established in layer 4.
Activity of neurons in area 6 of the cat during fixation
and eye movements
Authors: WEYAND THEODORE G. , GAFKA ADELE C.
Published: July 2002

We studied the visuomotor properties of 645 neurons
in area 6 of five cats trained in oculomotor tasks. The
area we recorded from corresponds well with territories
believed to contain the feline homologue of the frontal
eye fields observed in primates. Despite an expectation
that cells with pre-saccadic activity would be common,
only a small fraction (∼5%) of the cells displayed
activity that could be linked to subsequent saccadic eye
movements. These pre-motor cells appeared to be distributed
over a broad region of cortex mixed in with other cell
types. As in primates, saccade-related activity tended
to occur only during “purposeful” saccades.
At least 30% (208/645) of the neurons were visual, with
many of these cells possessing huge receptive fields that
appeared to include the entire contralateral visual field.
Visual responsiveness was generally attenuated by fixation
during the oculomotor tasks. Although attentional mechanisms
may play a role in this attenuation, this cortical area
also exhibits powerful lateral interactions in which spatially
displaced visual stimuli suppress each other. Most cells,
visually responsive or not, were affected by fixation.
Nearly equal proportions of cells showed increases or decreases
in activity during fixation. For many of the cells affected
by fixation, the source of this modulation appears to reflect
cognitive, rather than sensory or motor processes. This
included cells that showed anticipatory activity, and cells
that responded to the reward only when it was presented
in the context of the task. Based on the paucity of pre-saccadic
neurons, it would be difficult to conclude that this region
of cortex in the cat is homologous to the frontal eye fields
of the monkey. However, when considered in the context
of differences in the oculomotor habits of these two animals,
we believe the homology fits. In addition to pre-motor
neurons, the properties of several other cell types found
in this area could contribute to the control of gaze.
Processing of first- and second-order motion signals by
neurons in area MT of the macaque monkey
Authors: O'KEEFE LAWRENCE P. , MOVSHON J. ANTHONY
Published: July 2002

Extrastriate cortical area MT is thought to process
behaviorally important visual motion signals. Psychophysical
studies suggest that visual motion signals may be analyzed
by multiple mechanisms, a “first-order” one
based on luminance, and a “second-order” one
based upon higher level cues (e.g. contrast, flicker).
Second-order motion is visible to human observers, but
should be invisible to first-order motion sensors. To learn
if area MT is involved in the analysis of second-order
motion, we measured responses to first- and second-order
gratings of single neurons in area MT (and in one experiment,
in area V1) in anesthetized, paralyzed macaque monkeys.
For each neuron, we measured directional and spatio-temporal
tuning with conventional first-order gratings and with
second-order gratings created by spatial modulation of
the flicker rate of a random texture. A minority of MT
and V1 neurons exhibited significant selectivity for direction
or orientation of second-order gratings. In nearly all
cells, response to second-order motion was weaker than
response to first-order motion. MT cells with significant
selectivity for second-order motion tended to be more responsive
and more sensitive to luminance contrast, but were in other
respects similar to the remaining MT neurons; they did
not appear to represent a distinct subpopulation. For those
cells selective for second-order motion, we found a correlation
between the preferred directions of first- and second-order
motion, and weak correlations in preferred spatial frequency.
These cells preferred lower temporal frequencies for second-order
motion than for first-order motion. A small proportion
of MT cells seemed to remain selective and responsive for
second-order motion. None of our small sample of V1 cells
did. Cells in this small population, but not others, may
perform “form-cue invariant” motion processing
(Albright, 1992).
The visual pigments of the bottlenose dolphin (Tursiops
truncatus)
Authors: FASICK JEFFRY I. , CRONIN THOMAS W. , HUNT DAVID M. , ROBINSON PHYLLIS R.
Published: July 2002

To assess the dolphin's capacity for color
vision and determine the absorption maxima of the dolphin
visual pigments, we have cloned and expressed the dolphin
opsin genes. On the basis of sequence homology with other
mammalian opsins, a dolphin rod and long-wavelength sensitive
(LWS) cone opsin cDNAs were identified. Both dolphin opsin
cDNAs were expressed in mammalian COS-7 cells. The resulting
proteins were reconstituted with the chromophore 11-cis-retinal
resulting in functional pigments with absorption maxima
(λmax) of 488 and 524 nm for the rod and
cone pigments respectively. These λmax values
are considerably blue shifted compared to those of many
terrestrial mammals. Although the dolphin possesses a gene
homologous to other mammalian short-wavelength sensitive
(SWS) opsins, it is not expressed in vivo and
has accumulated a number of deletions, including a frame-shift
mutation at nucleotide position 31. The dolphin therefore
lacks the common dichromatic form of color vision typical
of most terrestrial mammals.
Serotonin receptors modulate rod signals: A neuropharmacological
comparison of light- and dark-adapted retinas
Authors: JIN XIAO TAO , BRUNKEN WILLIAM J.
Published: July 2002

Previous physiological studies have shown that
serotonin (5-HT) reciprocally modulates ON and OFF channels
in the mammalian retina. This study was undertaken to determine
if the serotoninergic system is exclusively associated
with the rod pathway. We tested drugs specific to 5-HT3
receptor, a serotonin-gated ion channel, in both dark-
and light-adapted retina. Consistent with previous studies,
we demonstrated that 5-HT3 receptors modulate
the light-evoked responses of ganglion cells in the dark-adapted
state. Moreover, we have extended these prior studies and
shown that activation of the 5-HT3 receptor
is capable of completely blocking the light-evoked response
of OFF-center cells whereas inactivation of the 5-HT3
receptor is capable of completely blocking the light-evoked
responses of ON-center cells. In contrast, in light-adapted
retinae, serotonin agents failed to have any effect on
retinal processing. These data suggest that the serotoninergic
system in retina is (1) specifically associated with rod-related
pathways; and (2) exerts a powerful modulatory force over
information transfer in the retina. Together these observations
suggests that serotonin plays an important physiological
role in modulating retinal processing.
Biochemical and morphological analysis of non-NMDA receptor
mediated excitotoxicity in chick embryo retina
Authors: CHEN QUAN , OLNEY JOHN W. , PRICE MADELON T. , ROMANO CARMELO
Published: July 2002

Ionotropic glutamate receptors (iGluRs) are ligand-gated
ion channels that mediate glutamatergic neurotransmission,
and when pathologically overstimulated induce excitotoxic
neuronal death. Of the two families of iGluRs, the non-NMDA
receptors have received less experimental attention than
the NMDA receptors as mediators of neuronal death in in
vitro systems. We have demonstrated that non-NMDA
receptor activation is highly lethal for neurons of the
chick embryo retina, and further characterize this phenomenon
here. Treatment of isolated retinas with any of the non-NMDA
receptor agonists glutamate, AMPA, or KA, in the presence
of the NMDA receptor antagonist MK-801, led to pathomorphology
and cell death. KA was the most effective toxin. All of
KA-induced toxicity could be blocked by selective AMPA
receptor blockers. The toxicity of both AMPA and glutamate
could be greatly increased using cyclothiazide, which blocks
AMPA receptor desensitization. These results indicate that
KA is the most powerful toxin because it is a non-desensitizing
agonist at the AMPA receptors. Glutamate exhibited a paradoxical
ability to prevent KA-induced toxicity as measured by a
biochemical assay of cell death. Also, histological studies
indicated that glutamate selectively blocked KA-induced
pathomorphological changes in bipolar cells. This protective
effect of glutamate was not mimicked by AMPA, NMDA, or
any of several metabotropic receptor agonists, indicating
that it may be mediated by a receptor of undescribed pharmacology.
Distribution of the glycine transporter glyt-1 in mammalian
and nonmammalian retinae
Authors: POW DAVID V. , HENDRICKSON ANITA E.
Published: July 2002

We have examined the distribution of the glycine
transporter glyt-1 in retinae of macaques, cats, rabbits,
rats, and chickens. In all species, all glycine-containing
amacrine cells expressed immunoreactivity for glyt-1, though
the intensity of immunoreactivity for glyt-1 did not appear
to directly correlate with the intensity of immunoreactivity
for glycine in individual cells. A small subpopulation
of glycine-immunoreactive displaced amacrine cells or ganglion
cells also expressed glyt-1 in retinae from macaques, cats,
chickens, and rats but not in retinae from rabbits. In
addition, in all species examined, some displaced amacrine
cells also contained glycine but did not express glyt-1.
In monkeys, cats, and rats, populations of cells which
we interpret as being glycine-containing interplexiform
cells expressed glyt-1; these cells lacked a content of
glutamate, suggesting they are not bipolar cells. The glycine-containing
bipolar cells did not express glyt-1, suggesting that these
cells probably acquired their content of glycine by other
means such as via gap junctional connections with
glycine-containing amacrine cells.
Electrophysiological correlates of vernier and relative
motion mechanisms in human visual cortex
Authors: NORCIA ANTHONY M. , WESEMANN WOLFGANG , MANNY RUTH E.
Published: July 2002

Vernier onset/offset thresholds were measured both
psychophysically and with the steady-state VEP by introducing
a series of horizontal breaks in a vertical square-wave
luminance grating. Several diagnostic tests indicated that
the first harmonic component of the evoked response generated
by periodic modulation of offset gratings taps mechanisms
that encode the relative position of spatial features.
In the first test, a first harmonic component was only
found with targets that contained transitions between collinear
and noncollinear states. VEP vernier onset/offset thresholds
obtained with foveal viewing were in the range of 15–22
arc sec. Control experiments with transitions between symmetrical,
noncollinear patterns (relative motion) did not produce
first harmonic components, nor did full-field motion of
a collinear grating. A second series of experiments showed
that VEP thresholds based on the first harmonic component
of the vernier onset/offset response had an eccentricity
dependence that was very similar to that found in a psychophysical
discrimination task that required a left/right position
judgment (vernier acuity). Other recordings showed that
the first harmonic of the vernier onset/offset VEP was
degraded by the introduction of a gap between stimulus
elements, as is the displacement threshold. The vernier
onset/offset target also produced a second harmonic component
that was virtually identical to the one produced by a relative
motion stimulus. Displacement thresholds based on these
second harmonic components showed a more gradual decline
with retinal eccentricity than did the first harmonic component
elicited by vernier offsets. The second harmonic of the
vernier onset/offset VEP was relatively unaffected by the
introduction of gaps between the stimulus elements. The
first and second harmonic components of the vernier onset/offset
VEP thus tap different mechanisms, both of which support
displacement thresholds that are finer than the resolution
limits set by the spacing of the photoreceptors (hyperacuity).
Social policy implications of research in developmental psychopathology
Authors: CICCHETTI DANTE , TOTH SHEREE L.
Published: July 2002

In concluding his review of the historical underpinnings of the field of developmental

psychopathology, Cicchetti (1990) asserted the following:

. . . this discipline should contribute greatly to reducing the dualisms that exist between the clinical

study of and theoretical research into childhood and adult disorders, between the behavioral and

biological sciences, between developmental psychology and psychopathology, and between basic

and applied research. (p. 20)
Large deviation theory for stochastic difference
equations
Authors: KUSKE R. , KELLER J. B.
Published: July 2002

The probability density for the solution
yn of a stochastic difference
equation is considered. Following Knessl et al.
[1], it is shown to satisfy a master equation,
which is solved asymptotically for large values of the index
n. The method is illustrated by deriving the large
deviation results for a sum of independent identically
distributed random variables and for
the joint density of two dependent sums. Then it is applied
to a difference approximation to
the Helmholtz equation in a random medium. A large
deviation result is obtained for the
probability density of the decay rate of a solution of
this equation. Both the exponent and
the pre-exponential factor are determined.
Disability and contact with services in very elderly people
Authors: Dening Tom , Gabe Rhian
Published: July 2002

Introduction

Across the world, population structures are changing, with particularly rapid growth in the numbers of very old people. For example, in the USA, the number of people aged 85 or over is now around 4.6 million, having grown at nearly 4% per annum since 1980.1 It appears that human longevity has been increasing gradually over many years, with centenarians only appearing as a relatively recent phenomenon about 1800,2 the age of 110 being reached in the mid-20th century and 115 only by 1990. There is no sign of this extension of longevity slowing down

towards a presumed biological maximum. In addition to the increase in the maximum age, there is a decrease in mortality rates in almost all age groups, and there has been a considerable rise in the chances of surviving from age 60 to 80 over the last century, which will further increase the numbers of very old people. Furthermore, the death rate in England and Wales for people aged 85 or over has decreased throughout the twentieth century.3
RAPID RADIATION IN AFRAMOMUM (ZINGIBERACEAE):EVIDENCE FROM NUCLEAR RIBOSOMAL DNA INTERNAL TRANSCRIBED SPACER (ITS) SEQUENCES
Authors: HARRIS D. J. , POULSEN A. D. , FRIMODT-MØLLER C. , PRESTON J. , CRONK Q. C. B
Published: July 2002

Internal transcribed spacer (ITS) nrDNA sequences of 42 accessions (representing 28 species) of Aframomum revealed an unusually low level of sequence variation, suggesting a recent radiation of the genus in Africa. The sample of species analysed includes all the main morphological variation and is based on wide geographical sampling. The Aframomum sequences varied from 187bp to 190bp (ITS 1) and 215bp to 216bp (ITS 2). Pair-wise sequence difference between accessions varied from 0% (e.g. A. luteoalbum and A. thonneri) to 2.74% (e.g. A. sp. nov. B to A. pseudostipulare). This contrasts with a comparable data set for the SE Asian genus Alpinia in the same tribe (Alpineae) in which maximum pair-wise difference is six times greater (range 0.5–15.6%). A parsimony analysis of the in-group and out-group taxa supports the monophyly of the genus Aframomum, but does not resolve the relationships between the in-group species. Four putative multi-species groups, however, have some jackknife support. The species sampled vary greatly in vegetative, floral and fruit characters. This morphological variation is not reflected in the ITS sequence data. This may be a result of rapid radiation under conditions of Pleistocene climatic change and effective dispersal of seeds by primates.
Optimal Construction of Edge-Disjoint Paths in Random Regular Graphs
Authors: FRIEZE ALAN M. , ZHAO LEI
Published: July 2002

Given a graph G = (V, E) and a set of κ
pairs of vertices in V, we are interested in finding,
for each pair (ai, bi),
a path connecting ai to bi
such that the set of κ paths so found is
edge-disjoint. (For arbitrary graphs the problem is [Nscr ][Pscr ]-complete, although it is in
[Pscr ] if κ is fixed.)

We present a polynomial time randomized algorithm for finding edge-disjoint paths in
the random regular graph Gn,r,
for sufficiently large r. (The graph is chosen first, then an
adversary chooses the pairs of end-points.) We show that almost every
Gn,r is such that all
sets of κ = Ω(n/log n) pairs of vertices can be joined.
This is within a constant factor of the optimum.
FASHIONING AESTHETICISM BY AESTHETICIZING FASHION: WILDE, BEERBOHM, AND THE MALE AESTHETES’ SARTORIAL CODES
Authors: Schaffer Talia
Published: July 2002

“Strange, that a pair of silk stockings should so upset a nation.”

— Oscar Wilde, quoted in Richard Ellmann’s Oscar Wilde

TODAY, WE TEND TO ENVISION the male Aesthete as a lanky, long-haired swain outfitted in velveteen pantaloons and clutching an outsize sunflower, an image straight from George du Maurier’s Punch cartoons or Gilbert and Sullivan’s Patience. Serious scholars of Aestheticism often prefer to resist this parodic image, insisting on the movement’s significant philosophical development in Ruskin’s and Pater’s work.1 Yet Aesthetic fashion was not just a frivolous side effect of the movement. In fact, Aesthetic fashion was the focus of late-Victorian attention because it so clearly displayed the anxieties, stresses, and formulations of the movement. It was a battlefield for competing voices within Aestheticism; it was a stage whereon the various gender notions of the movement could be displayed; and it functioned as both a critique and a form of art. This article examines the theoretical rationales for Aesthetic fashion, focusing on the paradigmatic figures of Oscar Wilde, Max Beerbohm, and George du Maurier. They demonstrate how Aesthetic men developed new visual codes to reconfigure their fear of feminization, creating a new kind of body which could be read as an essential, unchanging, scholarly, and artistic icon.
Effects of forest fragmentation, introduced Rattus rattus and the role of exotic tree plantations and secondary vegetation for the conservation of an endemic rodent and a small lemur in littoral forests of southeastern Madagascar
Authors: Ramanamanjato Jean‐Baptiste , Ganzhorn Jörg U.
Published: July 2002

We sought to assess the effects of forest fragmentation, introduced Rattus rattus, exotic tree plantations and secondary vegetation on the endemic rodent Eliurus webbi (Nesomyinae) and the lemur Microcebus murinus in the littoral forests of southern Madagascar. For E. webbi the number of individuals caught, the body mass of males and the percentage of females in the population were positively correlated with the size of the forest fragments. Capture rates and population characteristics of the other two species were uncorrelated with fragment size. None of the endemic species was caught outside the native forest while R. rattus inhabited all vegetation formations except for a newly planted corridor of tree saplings. Capture rates of both endemic species were uncorrelated with the number of R. rattus caught at the same site and thus did not indicate replacement of native species by R. rattus. The study demonstrated negative effects of fragmentation on capture rates of E. webbi and changes in their population characteristics. Exotic tree plantations or secondary vegetation seem to represent unsuitable or marginal habitats for the endemic species.
In vivo mechanisms by which tumors producing thrombospondin 1 bypass its inhibitory effects
Authors: Filleur Stéphanie , Volpert Olga V. , Degeorges Armelle , Voland Carole , Reiher Frank , Clézardin Philippe , Bouck Noël , Cabon Florence
Published: July 2002

Thrombospondin 1 (TSP1) is a multifunctional protein able to activate TGFβ and to inhibit angiogenesis in vivo. Although usually thought of as an inhibitor of tumor growth, TSP1 may sometimes be present at high levels during tumor progression, suggesting that tumors can eventually overcome their anti-tumor effects. Using a tet-repressible expression system, we demonstrate that murine TSP1 delayed the onset of tumor growth when produced in the tumor bed by rat fibrosarcoma tumor cells or by stromal fibroblasts coinjected with unmodified C6 glioma tumor cells. Yet upon prolonged exposure to TSP1, tumors came to grow at the same rate in the presence as in the absence of TSP1 and transplantation experiments showed that they had become insensitive to inhibition by TSP1 in both syngeneic and immune compromised hosts. Tumor resistance to TSP1 developed as a result of the in vivo outgrowth of pre-existing tumor cell variants that (1) secreted increased amounts of angiogenic factors that counterbalanced the inhibitory effect of TSP1 on neovascularization and (2) grew more efficiently in the presence of TSP1-activated TGFβ. These results indicate that prolonged and continuous local delivery of a single multifunctional angiogenesis inhibitor like TSP1 to fast-growing tumors can lead to tumor resistance in vivo by fostering the outgrowth of subpopulations that are a by-product of the genetic instability of the tumor cells themselves.
The α subunit of E. coli RNA polymerase activates RNA binding by NusA
Authors: Mah Thien-Fah , Kuznedelov Konstantin , Mushegian Arcady , Severinov Konstantin , Greenblatt Jack
Published: July 2002

The Escherichia coli NusA protein modulates pausing, termination, and antitermination by associating with the transcribing RNA polymerase core enzyme. NusA can be covalently cross-linked to nascent RNA within a transcription complex, but does not bind RNA on its own. We have found that deletion of the 79 carboxy-terminal amino acids of the 495-amino-acid NusA protein allows NusA to bind RNA in gel mobility shift assays. The carboxy-terminal domain (CTD) of the α subunit of RNA polymerase, as well as the bacteriophage λ Ngene antiterminator protein, bind to carboxy-terminal regions of NusA and enable full-length NusA to bind RNA. Binding of NusA to RNA in the presence of α or N involves an amino-terminal S1 homology region that is otherwise inactive in full-length NusA. The interaction of the α-CTD with full-length NusA stimulates termination. N may prevent termination by inducing NusA to interact with N utilization (nut) site RNA rather than RNA near the 3′ end of the nascent transcript. Sequence analysis showed that the α-CTD contains a modified helix–hairpin–helix motif (HhH), which is also conserved in the carboxy-terminal regions of some eubacterial NusA proteins. These HhH motifs may mediate protein–protein interactions in NusA and the α-CTD.
Multiple roles for the yeast SUB2/yUAP56 gene in splicing
Authors: Libri Domenico , Graziani Natacha , Saguez Cyril , Boulay J.
Published: July 2002

The UAP56 gene has been shown to be required for prespliceosome assembly in mammals. We report here the isolation of theSchizosaccharomyces pombe ortholog of this gene by heterologous complementation of a combinedPRP40HA3/nam8Δ defect in budding yeast. The Saccharomyces cerevisiae ortholog,YDL084w/SUB2, is also able to suppress this defect. We show that SUB2 is involved in splicing in vivo as well as in vitro. Sub2 defective extracts form a stalled intermediate that contains U2snRNP and can be chased into functional spliceosomes. Our experiments also suggest a role for this protein in events that precede prespliceosome formation. Data reported here as well as in the accompanying papers strongly implicate Sub2p in multiple steps of the spliceosome assembly process.
Gene Expression Profiling in Human Fetal Liver and Identification of Tissue- and Developmental-Stage-Specific Genes through Compiled Expression Profiles and Efficient Cloning of Full-Length cDNAs
Authors: Yu Yongtao , Zhang Chenggang , Zhou Gangqiao , Wu Songfeng , Qu Xianghu , Wei Handong , Xing Guichun , Dong Chunna , Zhai Yun , Wan Jinghong , Ouyang Shuguang , Li Li , Zhang Shaowen , Zhou Kaixin , Zhang Yinan , Wu Chutse , He Fuchu
Published: July 2002

Fetal liver intriguingly consists of hepatic parenchymal cells and hematopoietic stem/progenitor cells. Human fetal liver aged 22 wk of gestation (HFL22w) corresponds to the turning point between immigration and emigration of the hematopoietic system. To gain further molecular insight into its developmental and functional characteristics, HFL22w was studied by generating expressed sequence tags (ESTs) and by analyzing the compiled expression profiles of liver at different developmental stages. A total of 13,077 ESTs were sequenced from a 3′-directed cDNA library of HFL22w, and classified as follows: 5819 (44.5%) matched to known genes; 5460 (41.8%) exhibited no significant homology to known genes; and the remaining 1798 (13.7%) were genomic sequences of unknown function, mitochondrial genomic sequences, or repetitive sequences. Integration of ESTs of known human genes generated a profile including 1660 genes that could be divided into 15 gene categories according to their functions. Genes related to general housekeeping, ESTs associated with hematopoiesis, and liver-specific genes were highly expressed. Genes for signal transduction and those associated with diseases, abnormalities, or transcription regulation were also noticeably active. By comparing the expression profiles, we identified six gene groups that were associated with different developmental stages of human fetal liver, tumorigenesis, different physiological functions of Itoh cells against the other types of hepatic cells, and fetal hematopoiesis. The gene expression profile therefore reflected the unique functional characteristics of HFL22w remarkably. Meanwhile, 110 full-length cDNAs of novel genes were cloned and sequenced. These novel genes might contribute to our understanding of the unique functional characteristics of the human fetal liver at 22 wk.

[The sequence data described in this paper have been submitted to the GenBank data library under the accession nos. listed in Table 6 herein]
Characterization of CAX4, an Arabidopsis H+/Cation Antiporter
Authors: Cheng Ning-hui , Pittman Jon K. , Shigaki Toshiro , Hirschi Kendal D.
Published: July 2002

Ion compartmentalization is essential for plant growth and development. The Arabidopsis open reading frames for CAX1, CAX2, and CAX3 (cation exchangers 1, 2, and 3) were previously identified as transporters that may modulate ion fluxes across the vacuolar membrane. To understand the diversity and role of H+/cation transporters in controlling plant ion levels, another homolog of theCAX genes, CAX4, was cloned from an Arabidopsis cDNA library. CAX4 is 53% identical to CAX1 at the amino acid level, 42% identical to CAX2, and 54% identical to CAX3.CAX4 transcripts appeared to be expressed at low levels in all tissues and levels of CAX4 RNA increased after Mn2+, Na+, and Ni2+ treatment. An N-terminal CAX4-hemagglutinin fusion appeared to localize to both yeast and plant vacuolar membranes. When expressed in yeast, CAX4, like CAX3, failed to suppress the Ca2+ sensitivity of yeast strains deficient in vacuolar Ca2+ transport. Several modifications to CAX4 allowed the protein to transport Ca2+. Addition of amino acids to the N terminus of CAX4 and CAX3 caused both transporters to suppress the sensitivity of yeast strains deficient in vacuolar Ca2+ transport. These findings suggest that CAX transporters may modulate their ion transport properties through alterations at the N terminus.
Identification of Arabidopsis Ethylene-Responsive Element Binding Factors with Distinct Induction Kinetics after Pathogen Infection,
Authors: Oñate-Sánchez Luis , Singh Karam B.
Published: July 2002

Ethylene-responsive element binding factors (ERF) proteins are plant-specific transcription factors, many of which have been linked to stress responses. We have identified four Arabidopsis ERF genes whose expression was specifically induced by avirulent and virulent strains of the bacterial pathogen Pseudomonas syringae pv tomato, with overlapping but distinct induction kinetics. However, a delay in ERFmRNA accumulation after infection with the virulent strain was observed when compared with the avirulent strain. The induction ofERF gene expression in most cases preceded the mRNA accumulation of a basic chitinase gene, a potential downstream target for one or more of these ERFs. The expression of the ERFgenes was examined among different Arabidopsis tissues, in response to the signaling molecules ethylene, methyl jasmonate, and salicylic acid (SA), and in Arabidopsis mutants with decreased or enhanced susceptibility to pathogens, and significant differences were observed. For example, in seedlings, some of the ERF genes were not induced by SA in the wild-type but were SA responsive in thepad4-1 mutant, suggesting that PAD4-1, which acts upstream of SA accumulation, is also involved in repressing the SA-induced expression of specific ERF genes. The four ERF proteins were shown to contain transcriptional activation domains. These results suggest that transcriptional activation cascades involving ERF proteins may be important for plant defense to pathogen attack and that some ERF family members could be involved in the cross-talk between SA- and jasmonic acid-signaling pathways.