bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical sand wave dynamics in one-directional water flows
Authors: NIKORA VLADIMIR I. , SUKHODOLOV ALEXANDER N. , ROWINSKI PAWEL M. 
Published: July 2002

Moving sand waves and the overlying tubulent flow were

measured on the Wilga River

in Poland, and the Tirnava Mica and Buzau Rivers in Romania. Bottom elevations
and

flow velocities were measured at six points simultaneously by multi-channel
measuring

systems. From these data, the linear and two-dimensional sections of the

three-dimensional correlation and structure functions and various projections
of

sand wave three-dimensional spectra were investigated.It was found that the longitudinal wavenumber spectra of the sand waves
in the

region of large wavenumbers followed Hino's −3 law

(S(Kx)

∝K−3x)

quite satisfactorily, confirming the theoretical predictions of Hino

(1968) and Jain & Kennedy

(1974). However, in contrast to Hino (1968), the sand wave frequency spectrum
in the

high-frequency region was approximated by a power function with the exponent

−2, while in the lower-frequency region this exponent is close to
−3.A dispersion relation for sand waves has been investigated from analysis
of

structure functions, frequency spectra and the cross-correlation

functions method. For

wavelengths less than 0.15–0.25 of the flow depth, their

propagation velocity C is

inversely proportional to the wavelength λ. When the wavelengths
of spectral

components are as large as 3–4 times the flow depth, no

dispersion occurs. These results

proved to be in good qualitative agreement with the theoretical dispersion
relation

derived from the potential-flow-based analytical models (Kennedy 1969;
Jain &

Kennedy 1974). We also present another, physically-based, explanation of
this

phenomenon, introducing two types of sand movement in the form of sand
waves. The

first type (I) is for the region of large wavenumbers (small wavelengths)
and

the second one (II) is for the region of small wavenumbers (large wavelengths).

The small sand waves move due to the motion of individual sand particles
(type I,

C∝λ−1) while

larger sand waves propagate as a result of the motion of smaller waves
on their

upstream slopes (type II, C∝λ0). Like

the sand particles in the first type, these smaller

waves redistribute sand from upstream slopes to downstream ones. Both types
result

in sand wave movement downstream but with a different propagation velocity.The main characteristics of turbulence, as well as the quantitative
values

characterizing the modulation of turbulence by sand waves, are also presented.
Evolution of a wave packet into vortex loops in a
laminar separation bubble
Authors: WATMUFF JONATHAN H. 
Published: July 2002

A laminar boundary layer develops in a favourable pressure gradient where the
velocity profiles asymptote to the Falkner & Skan similarity solution. Flying-hot-wire
measurements show that the layer separates just downstream of a subsequent region of
adverse pressure gradient, leading to the formation of a thin separation bubble. In an
effort to gain insight into the nature of the instability mechanisms, a small-magnitude
impulsive disturbance is introduced through a hole in the test surface at the pressure
minimum. The facility and all operating procedures are totally automated and phase-averaged data are acquired on unprecedently large and spatially dense measurement
grids. The evolution of the disturbance is tracked all the way into the reattachment
region and beyond into the fully turbulent boundary layer. The spatial resolution of
the data provides a level of detail that is usually associated with computations.Initially, a wave packet develops which maintains the same bounded shape and
form, while the amplitude decays exponentially with streamwise distance. Following
separation, the rate of decay diminishes and a point of minimum amplitude is reached,
where the wave packet begins to exhibit dispersive characteristics. The amplitude then
grows exponentially and there is an increase in the number of waves within the packet.
The region leading up to and including the reattachment has been measured with a
cross-wire probe and contours of spanwise vorticity in the centreline plane clearly show
that the wave packet is associated with the cat's eye pattern that is a characteristic of
Kelvin–Helmholtz instability. Further streamwise development leads to the formation
of roll-ups and contour surfaces of vorticity magnitude show that they are three-dimensional. Beyond this point, the behaviour is nonlinear and the roll-ups evolve
into a group of large-scale vortex loops in the vicinity of the reattachment. Closely
spaced cross-wire measurements are continued in the downstream turbulent boundary
layer and Taylor's hypothesis is applied to data on spanwise planes to generate three-dimensional velocity fields. The derived vorticity magnitude distribution demonstrates
that the second vortex loop, which emerges in the reattachment region, retains its
identity in the turbulent boundary layer and it persists until the end of the test section.
A scalar subgrid model with flow structure for
large-eddy simulations of scalar variances
Authors: FLOHR P. , VASSILICOS J. C. 
Published: July 2002

A new model to simulate passive scalar fields in large-eddy simulations of turbulence
is presented. The scalar field is described by clouds of tracer particles and the subgrid
contribution of the tracer displacement is modelled by a kinematic model which obeys
Kolmogorov's inertial-range scaling, is incompressible and incorporates turbulent-like
flow structure of the turbulent small scales. This makes it possible to study the scalar
variance field with inertial-range effects explicitly resolved by the kinematic subgrid
field while the LES determines the value of the Lagrangian integral time scale TL.
In this way, the modelling approach does not rely on unknown Lagrangian input
parameters which determine the absolute value of the scalar variance.The mean separation of particle pairs displays a well-defined Richardson scaling
in the inertial range, and we find that the Richardson constant
GΔ ≈ 0.07 which is
small compared to the value obtained from stochastic models with the same TL. The
probability density function of the separation of particle pairs is found to be highly
non-Gaussian in the inertial range of times and for long times becomes Gaussian.
We compute the scalar variance field for an instantaneous line source and find good
agreement with experimental data.
Sex differences in event-related risk for major depression
Authors: MACIEJEWSKI P. K. , PRIGERSON H. G. , MAZURE C. M. 
Published: July 2002

Background. This study sought to determine if women are more likely than men to experience an episode of major depression in response to stressful life events.Method. Sex differences in event-related risk for depression were examined by means of secondary analyses employing data from the Americans' Changing Lives study. The occurrence and time of occurrence of depression onset and instances of stressful life events within a 12-month period preceding a structured interview were documented in a community-based sample of 1024 men and 1800 women. Survival analytical techniques were used to examine sex differences in risk for depression associated with generic and specific stressful life events.Results. Women were approximately three times more likely than men to experience major depression in response to any stressful life event. Women and men did not differ in risk for depression associated with the death of a spouse or child, events affecting their relationship to a spouse/partner (divorce and marital/love problems) or events corresponding to acute financial or legal difficulties. Women were at elevated risk for depression associated with more distant interpersonal losses (death of a close friend or relative) and other types of events (change of residence, physical attack, or life-threatening illness/injury).Conclusion. Stressful life events overall, with some exceptions among specific event types, pose a greater risk for depression among women compared to men.
Vulnerability to assaultive violence:
further specification of the sex difference in
post-traumatic stress disorder
Authors: BRESLAU N. , CHILCOAT H. D. , KESSLER R. C. , PETERSON E. L. , LUCIA V. C. 
Published: July 2002

Background. We examine potential sources of the sex differences in post-traumatic stress disorder
(PTSD) in the community.Methods. Data were obtained from a representative sample of 2181 persons aged 18–45 years in the
Detroit primary metropolitan statistical area, which is a six-county area containing more than four
million residents. A random digit dialling method was used to select the sample and a computer-assisted telephone interview was used to obtain the data. DSM-IV PTSD was assessed with respect
to a randomly selected trauma from the list of qualifying traumas reported by each respondent.Results. The lifetime prevalence of exposure and the mean number of traumas were lower in females
than males. The overall conditional risk of PTSD (i.e. the probability of PTSD among those
exposed to a trauma) was approximately twofold higher in females than males, adjusting for the sex
difference in the distribution of trauma types. The sex difference was due primarily to females'
greater risk following assaultive violence. The sex difference in the avoidance and numbing
symptom group following assaultive violence exceeded the sex differences in other symptom groups.Conclusions. Future research should focus on sex differences in the response to assaultive violence,
including potential explanations for females' greater probability to experience avoidance and
numbing.
NMR-based screening in drug discovery
Authors: Hajduk Philip J. , Meadows Robert P. , Fesik Stephen W. 
Published: July 2002

1. Introduction 2112. Screening methods 2132.1 Chemical shifts 2132.2 Diffusion 2142.3 Transverse relaxation 2182.4 Nuclear Overhauser effects 2183. Strategies for drug discovery and design 2213.1 Fragment-based methods 2213.1.1 Linked-fragment approach 2213.1.2 Directed combinatorial libraries 2223.1.3 Modification of high-affinity ligands 2233.1.4 Solvent mapping techniques 2233.2 High-throughput NMR-based screening 2243.3 Enzymatic assays 2264. Discovery of novel ligands 2274.1 High-affinity ligands for FKBP 2274.2 Potent inhibitors of stromelysin 2294.3 Ligands for the DNA-binding domain of the E2 protein 2334.4 Discovery of Erm methyltransferase inhibitors 2334.5 Phosphotyrosine mimetics for SH2 domains 2365. Conclusions 2376. References 237A critical step in the drug discovery process is the identification of high-affinity ligands for
macromolecular targets. Traditionally, the identification of such lead compounds has been
accomplished through the high-throughout screening (HTS) of corporate compound
repositories. Conventional HTS methodology has enjoyed widespread application and
success in the pharmaceutical industry and, through recent technological advances in
screening (Fernandes, 1998; Oldenburg et al. 1998; Silverman et al. 1998) and combinatorial
chemistry (Fauchere et al. 1998; Fecik et al. 1998), these programs will continue to have a
prominent role in drug discovery. However, suitable leads cannot always be found using
conventional methods. This is not surprising since typical corporate libraries contain fewer
than 106 compounds compared with the estimated 1050–1080 universe of compounds (Martin,
1997). In addition, most conventional assays are limited to screening libraries of compounds
against proteins with known function, excluding the large number of targets becoming
available from genomics research.Recently, a number of NMR-based screening methods have been employed to identify
and design lead ligands for protein targets (see Table 1). These NMR-based strategies can
augment ongoing conventional HTS for identifying leads and can be used to aid in lead
optimization. All of these techniques take advantage of the fact that upon complex formation
between a target molecule and a ligand, significant perturbations can be observed in NMR-sensitive parameters of either the target or the ligand. These perturbations can be used
qualitatively to detect ligand binding or quantitatively to assess the strength of the binding
interaction. In addition, some of the techniques allow the identification of the ligand binding
site or which part of the ligand is responsible for interacting with the target. In this article,
the current state of NMR-based screening is reviewed.
Neurobiology of the structure of personality: Dopamine, facilitation of incentive motivation, and extraversion
Authors: Depue Richard A. , Collins Paul F. 
Published: July 2002

Extraversion has two central characteristics: (1)
interpersonal engagement, which consists of affiliation
(enjoying and valuing close interpersonal bonds, being warm and
affectionate) and agency (being socially dominant, enjoying leadership
roles, being assertive, being exhibitionistic, and having a sense of
potency in accomplishing goals) and (2) impulsivity, which
emerges from the interaction of extraversion and a second, independent
trait (constraint). Agency is a more general motivational disposition
that includes dominance, ambition, mastery, efficacy, and achievement.
Positive affect (a combination of positive feelings and motivation) is
closely associated with extraversion. Extraversion is accordingly
based on positive incentive motivation.Parallels between extraversion (particularly its agency component)
and a mammalian behavioral approach system based on positive incentive
motivation implicate a neuroanatomical network and modulatory
neurotransmitters in the processing of incentive motivation. A
corticolimbic-striatal-thalamic network (1) integrates the salient
incentive context in the medial orbital cortex, amygdala, and
hippocampus; (2) encodes the intensity of incentive stimuli in a
motive circuit composed of the nucleus accumbens, ventral pallidum,
and ventral tegmental area dopamine projection system; and (3) creates
an incentive motivational state that can be transmitted to the motor
system.Individual differences in the functioning of this network arise
from functional variation in the ventral tegmental area dopamine
projections, which are directly involved in coding the intensity of
incentive motivation. The animal evidence suggests that there are
three neurodevelopmental sources of individual differences in
dopamine: genetic, “experience-expectant,” and
“experience-dependent.” Individual differences in
dopamine promote variation in the heterosynaptic plasticity that
enhances the connection between incentive context and incentive
motivation and behavior.Our psychobiological threshold model explains the effects of
individual differences in dopamine transmission on behavior, and
their relation to personality traits is discussed.
Status and distribution of khulan (Equus hemionus) in Mongolia
Authors: Reading Richard P. , Mix Henry M. , Lhagvasuren Badamjaviin , Feh Claudia , Kane David P. , Dulamtseren S. , Enkhbold Sumyain 
Published: July 2002

AbstractThe Asiatic wild ass Equus hemionus, or khulan, once ranged across much of Central Asia, but is now globally threatened. The largest free‐ranging populations are now restricted to a 250‐km wide area (range 100–400 km) across the Gobi Desert region of southern Mongolia. Over the last 23 years the population has moved further north and east into its former range. Surveys conducted in the 1970s and 1980s estimated that the Mongolian population contained fewer than 15 000 animals and was declining as a result of human exploitation and livestock competition. Aerial surveys (one in autumn 1994, two in spring 1997) were flown as line transects over portions of the khulan's range in Mongolia and ground surveys (five in spring, summer, and autumn 1994–97) were conducted by vehicle and foot. Sample sizes and areas surveyed were larger than previous surveys, and our methods were often more systematic. Population size was estimated at 33 000–63 000 wild asses in Mongolia. Animal density ranged from 4.2±1.3 to 19.1±3.2 per 100 km2. Mean group size ranged from four to 35 animals in the south‐western Gobi, four to seven animals in the southern Gobi, and three to 18 in the south‐eastern Gobi. Our data suggest that Mongolia is the most important stronghold for the conservation of E. hemionus. Conservation management continues to be challenging because intensive studies on khulan biology and ecology are just beginning. As a free‐market economy continues to emerge in Mongolia, pressure from resource extraction interests and nomadic livestock herders to remove the khulan's protected status, permit harvesting and halt population growth and expansion, also makes implementation of research and conservation management programs more imperative.
Dimorphism and the functional basis of claw strength in six brachyuran crabs
Authors: Schenk Steve C. , Wainwright Peter C. 
Published: July 2002

AbstractBy examining the morphological basis of force generation in the chelae (claws) of both molluscivorous and non‐molluscivorous crabs, it is possible to understand better the difference between general crab claw design and the morphology associated with durophagy. This comparative study investigates the morphology underlying claw force production and intraspecific claw dimorphism in six brachyuran crabs: Callinectes sapidus (Portunidae), Libinia emarginata (Majidae), Ocypode quadrata (Ocypodidae), Menippe mercenaria (Xanthidae), Panopeus herbstii (Xanthidae), and P. obesus (Xanthidae). The crushers of the three molluscivorous xanthids consistently proved to be morphologically ‘strong,’ having largest mechanical advantages (MAs), mean angles of pinnation (MAPs), and physiological cross‐sectional areas (PCSAs). However, some patterns of variation (e.g. low MA in C. sapidus, indistinguishable force generation potential in the xanthids) suggested that a quantitative assessment of occlusion and dentition is needed to understand fully the relationship between force generation and diet. Interspecific differences in force generation potential seemed mainly to be a function of differences in chela closer muscle cross‐sectional area, due to a sixfold variation in apodeme area. Intraspecific dimorphism was generally defined by tall crushers with long in‐levers, though O. quadrata exhibited an extreme dimorphism suggesting that factors unrelated to a speed–strength dichotomy (e.g. sexual selection) have shaped dimorphism of that species. It is concluded here that: (1) the majority of interspecific claw strength variation is a function of closer muscle cross‐sectional area; (2) variation in claw morphology related to force production and transmission does have some relation to hardness of diet; (3) claw dimorphism in many species does seem to be related to strength and speed trade‐offs; (4) factors besides molluscivory must be considered to understand claw evolution fully; (5) a quantitative assessment of force distribution, lacking in the literature, is essential for a more complete understanding of the relationship between claw design and ecological function.
Nimrod: a system for generating automated very short range forecasts
Authors: Golding B W 
Published: July 2002

AbstractA very short range forecasting system has been developed which integrates nowcasting techniques with Numerical Weather Prediction (NWP) model products to provide forecasts over the UK and surrounding waters up to six hours ahead. There are three main components, producing analyses and forecasts of precipitation, cloud and visibility, respectively. The precipitation rate analysis uses processed radar and satellite data, together with surface reports and NWP fields. The forecast is based on an object advection technique, modified for growth and decay using model products. Related variables, such as precipitation type, are also diagnosed using the NWP fields. The cloud analysis is based largely on satellite imagery and surface reports, the forecast being carried out in a similar way to precipitation rate. The visibility analysis combines surface reports with NWP model fields and satellite imagery: Meteosat during the day and NOAA–AVHRR at night. The forecast is an extrapolation using trends from the NWP model, and relaxing towards the model values themselves. Results show a substantial improvement over both persistence and raw NWP model products. Copyright © 1998 Royal Meteorological Society
Circadian Rhythms Confer a Higher Level of Fitness to Arabidopsis Plants
Authors: Green Rachel M. , Tingay Sonia , Wang Zhi-Yong , Tobin Elaine M. 
Published: July 2002

Abstract
Circadian rhythms have been demonstrated in organisms across the taxonomic spectrum. In view of their widespread occurrence, the adaptive significance of these rhythms is of interest. We have previously shown that constitutive expression of theCCA1 (CIRCADIAN CLOCK ASSOCIATED 1) gene in Arabidopsis plants (CCA1-ox) results in loss of circadian rhythmicity. Here, we demonstrate that these CCA1-ox plants retain the ability to respond to diurnal changes in light. Thus, transcript levels of several circadian-regulated genes, as well as CCA1 itself and the closely related LHY, oscillate robustly if CCA1-ox plants are grown under diurnal conditions. However, in contrast with wild-type plants in which transcript levels change in anticipation of the dark/light transitions, the CCA1-ox plants have lost the ability to anticipate this daily change in their environment. We have used CCA1-ox lines to examine the effects of loss of circadian regulation on the fitness of an organism. CCA1-ox plants flowered later, especially under long-day conditions, and were less viable under very short-day conditions than their wild-type counterparts. In addition, we demonstrate that two other circadian rhythm mutants, LHY-ox and elf3, have low-viability phenotypes. Our findings demonstrate the adaptive advantage of circadian rhythms in Arabidopsis.
Uptake Kinetics of Arsenic Species in Rice Plants
Authors: Abedin Mohammed Joinal , Feldmann Jörg , Meharg Andy A. 
Published: July 2002

Abstract
Arsenic (As) finds its way into soils used for rice (Oryza sativa) cultivation through polluted irrigation water, and through historic contamination with As-based pesticides. As is known to be present as a number of chemical species in such soils, so we wished to investigate how these species were accumulated by rice. As species found in soil solution from a greenhouse experiment where rice was irrigated with arsenate contaminated water were arsenite, arsenate, dimethylarsinic acid, and monomethylarsonic acid. The short-term uptake kinetics for these four As species were determined in 7-d-old excised rice roots. High-affinity uptake (0–0.0532 mm) for arsenite and arsenate with eight rice varieties, covering two growing seasons, rice var. Boro (dry season) and rice var. Aman (wet season), showed that uptake of both arsenite and arsenate by Boro varieties was less than that of Aman varieties. Arsenite uptake was active, and was taken up at approximately the same rate as arsenate. Greater uptake of arsenite, compared with arsenate, was found at higher substrate concentration (low-affinity uptake system). Competitive inhibition of uptake with phosphate showed that arsenite and arsenate were taken up by different uptake systems because arsenate uptake was strongly suppressed in the presence of phosphate, whereas arsenite transport was not affected by phosphate. At a slow rate, there was a hyperbolic uptake of monomethylarsonic acid, and limited uptake of dimethylarsinic acid.