bluuebunny/crossref_metadata_2025_split huggingface dataset:
J‐integral fracture toughness and tearing modulus measurement of radiation cross‐linked UHMWPE
Authors: Gomoll A. , Wanich T. , Bellare A. 
Published: October 2002

AbstractRadiation and chemical cross‐linking of medical grade ultrahigh molecular weight polyethylene (UHMWPE) has recently been utilized in an effort to improve wear performance of total joint replacement components. However, reductions in mechanical properties with cross‐linking are cause for concern regarding the use of cross‐linked UHMWPE for high‐stress applications such as in total knee replacement prostheses. In this study, the fracture behavior of radiation cross‐linked UHMWPE was compared to that of uncross‐linked UHMWPE. The Rice and Sorensen model that utilizes mechanical parameters obtained from uniaxial tensile and compact tension tests was used to calculate the steady state J‐integral fracture toughness, Jss, for radiation cross‐linked UHMWPE. Jss decreased monotonically with increase in radiation dose. UHMWPE exhibited tough, ductile tearing behavior with stable crack growth when it was cross‐linked using a gamma radiation dose of 0–50 kGy. However, in cross‐linked UHMWPE irradiated to a dose of 100 and 200 kGy, unstable fracture occurred spontaneously upon attaining the initial crack driving force, J1c. This indicates that a high degree of cross‐linking is less desirable for high‐stress applications in orthopaedic implants. However, a substantial increase in J1c, even at a low degree of cross‐linking, suggests that a low degree of cross‐linking may be beneficial for resistance to delamination and catastrophic failure, both of which require an initiation step for the fracture to propagate in the material. This mechanical test should, however, be considered along with fatigue tests and joint simulator testing before determination of an appropriate amount of cross‐linking for total joint replacement prostheses that experience high stresses.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Neither increased nor decreased availability of cortical serotonin (5HT) disturbs barrel field formation in isocaloric undernourished rat pups
Authors: Gutiérrez‐Ospina Gabriel , Manjarrez‐Gutiérrez Gabriel , González Cesar , López Sandra , Herrera Rocı́o , Medina Aguirre Ivett , Hernández‐R Jorge 
Published: October 2002

AbstractSerotonin (5HT) is expressed transiently in primary sensory areas of the rat neocortex during the establishment of the thalamo‐cortical topography and somatotopy. The precise role of 5HT during the specification of neocortical areas is still uncertain. We evaluated the effects of increasing and decreasing cortical serotonin concentrations on the specification of the barrel cortex using a rat model of isocaloric undernutrition. This manipulation increases brain 5HT levels during brain development. Undernourished animals were also treated with p‐clorophenylalanine; an inhibitor of 5HT synthesis. Barrels representing the head were readily seen at postnatal day 5 in control and p‐clorophenylalanine treated rats. In contrast, undernourished rats treated or not with p‐clorophenylalanine showed no barrels representing the head but until postnatal day 7. Chromatographic analyses demonstrated that the concentration of cortical 5HT increased by 50% in undernourished pups during barrel field formation. Control and undernourished animals treated with p‐clorophenylalanine had a significant reduction (90%) of 5HT in the cortex. The overall geometry of the barrel field and of individual barrels was similar among animal groups. Our results support that 5HT plays a small role in triggering and timing barrel field somatotopy.
Neonatal electrolytic lesions of the basal forebrain stunt plasticity in mouse barrel field cortex
Authors: Nishimura Akira , Hohmann Christine F. , Johnston Michael V. , Blue Mary E. 
Published: October 2002

AbstractPrevious studies have shown that neonatal electrolytic lesions of basal forebrain cholinergic projections in mice lead to a transient cholinergic depletion of neocortex and to permanent alterations in cortical cytoarchitecture and in cognitive performance. The present study examines whether neonatal electrolytic lesions of the basal forebrain modify neocortical plasticity. Using cytochrome oxidase histochemistry, we compared cross‐sectional areas of individual barrels in the barrel field of four groups of postnatal day 8 (P8) old mice that on P1 received either (1) right electrolytic lesions of the basal forebrain, (2) left C row 1–4 whisker follicle ablations, (3) combined lesion treatments or (4) ice anesthesia only. The size of barrels in basal forebrain lesioned animals was not significantly different from controls. However, the plastic response to whisker removal was compromised in basal forebrain lesioned animals. An index of plasticity, the ratio of row D/row C areas, was reduced significantly in the combined nBM lesioned/follicle ablation group. Compared to whisker‐lesioned mice, the expansion in rows B and D and the shrinkage in the lesioned row C area were diminished in the combined treatment group. The present findings correspond to those from a study of rats injected with a cholinergic immunotoxin [Cereb. Cortex 8 (1998) 63]. These results suggest that cholinergic inputs play a role in regulating plasticity as well as in the morphogenesis of mouse sensory‐motor cortex.
SETS OF UNIQUENESS OF SERIES OF STOCHASTICALLY INDEPENDENT FUNCTIONS
Authors: Freniche Francisco J. , Ríos-Collantes-de-Terán Ricardo 
Published: October 2002

AbstractIt is shown that, for every sequence $(f_n)$ of stochastically independent functions defined on $[0,1]$—of mean zero and variance one, uniformly bounded by $M$—if the series $\sum_{n=1}^\infty a_nf_n$ converges to some constant on a set of positive measure, then there are only finitely many non-null coefficients $a_n$, extending similar results by Stechkin and Ul’yanov on the Rademacher system. The best constant $C_M$ is computed such that for every such sequence $(f_n)$ any set of measure strictly less than $C_M$ is a set of uniqueness for $(f_n)$.AMS 2000 Mathematics subject classification:Primary 42C25. Secondary 60G50
ON THE STABILITY OF RICCATI DIFFERENTIAL EQUATION X˙ = TX+Q(X) IN ℝn
Authors: Mencinger Matej 
Published: October 2002

AbstractThe system $\dot{X}=TX+Q(X)$ (in $\mathbb{R}^{n}$), where $T$ is linear and $Q$ is quadratic, is considered via commutative algebras. The case of the linearized system having a centre manifold spanned on vectors $E_{1}$, $E_{2}$ (and $TE_{1}=\omega E_{2}$, $TE_{2}=-\omega E_{1}$) is studied. It is shown that for $\Span(E_{1},E_{2})$ being a subalgebra (of the algebra corresponding to the form $Q(X)$), the system is stable. Necessary and sufficient conditions are given for stability of the system in the case where $\mathrm{span}(E_{1},E_{2})$ is not a subalgebra.AMS 2000 Mathematics subject classification: Primary 34A34; 34C15; 34C27; 34C35. Secondary 13M99
ON LOCAL FINITENESS OF PERIODIC RESIDUALLY FINITE GROUPS
Authors: Kuzucuoğlu Mahmut , Shumyatsky Pavel 
Published: October 2002

AbstractLet $G$ be a periodic residually finite group containing a nilpotent subgroup $A$ such that $C_G(A)$ is finite. We show that if $\langle A,A^g\rangle$ is finite for any $g\in G$, then $G$ is locally finite.AMS 2000 Mathematics subject classification: Primary 20F50
ON THE GROUP AutΩ(X)
Authors: Paves˘ić Petar 
Published: October 2002

AbstractFelix and Murillo introduced the group $\mathrm{Aut}_\varOmega(X)$ of self-maps $f$ of $X$, which satisfy $\sOm f=1_{\varOmega X}$, and proved that the group is nilpotent with the order of nilpotency bounded by the Lusternik–Schnirelmann category of $X$. In this paper we construct a spectral sequence converging to the group $\mathrm{Aut}_\varOmega(X)$ and derive several interesting consequences.AMS 2000 Mathematics subject classification: Primary 55P42
STURM–LIOUVILLE PROBLEMS WITH BOUNDARY CONDITIONS RATIONALLY DEPENDENT ON THE EIGENPARAMETER. I
Authors: Binding Paul A. , Browne Patrick J. , Watson Bruce A. 
Published: October 2002

AbstractWe consider the Sturm–Liouville equation$$ -y''+qy=\lambda y\quad\text{on }[0,1], $$subject to the boundary conditions$$ y(0)\cos\alpha=y'(0)\sin\alpha,\quad\alpha\in[0,\pi), $$and$$\frac{y'}{y}(1)=a\lambda+b-\sum_{k=1}^N\frac{b_k}{\lambda-c_k}. $$Topics treated include existence and asymptotics of eigenvalues, oscillation of eigenfunctions, and transformations between such problems.AMS 2000 Mathematics subject classification: Primary 34B24; 34L20
ON A GAMMA FUNCTION INEQUALITY OF GAUTSCHI
Authors: Alzer Horst 
Published: October 2002

AbstractWe prove the following.(1) The inequalities$$ \biggl(2-\frac{1}{\varGamma(x)}\biggr)^{\!a}+\biggl(2-\frac{1}{\varGamma(1/x)}\biggr)^{\!a}\leq 2\leq\biggl(2-\frac{1}{\varGamma(x)}\biggr)^{\!b}+\biggl(2-\frac{1}{\varGamma(1/x)}\biggr)^{\!b} $$hold for all $x>0$ if and only if$$ -1.204\,64\ldots=2+\frac{1}{\gamma}-\frac{1}{6}\biggl(\frac{\pi}{\gamma}\biggr)^{\!2}\leq a\leq0\leq b. $$(2) For all real numbers $x\in(0,1]$ we have$$ x^{\alpha}\leq\frac{1}{2}\biggl(\frac{1}{\varGamma(x)}+\frac{1}{\varGamma(1/x)}\biggr)\leq x^{\beta}, $$with the best possible constants$$ \alpha=1.321\,76\dots\link{and}\beta=0. $$These theorems extend and complement a result of Gautschi (from 1974), who proved that for all $x>0$ the harmonic mean of $\varGamma(x)$ and $\varGamma(1/x)$ is greater than or equal to $1$.AMS 2000 Mathematics subject classification: Primary 33B15; 26D15
Effect of season on thermoregulatory responses and energy expenditure of goats on semi-arid range in India
Authors: SHINDE A. K. , BHATTA RAGHAVENDRA , SANKHYAN S. K. , VERMA D. L. 
Published: October 2002

A study of the physiological responses and energy expenditure of goats was carried out from June 1999 to May 2000 by conducting two experiments: one on bucks maintained on stall feeding in autumn 1999 (Expt 1) followed by year-round grazing on native ranges over three seasons: monsoon, winter and summer (Expt 2). Physiological responses and energy expenditure (EE) measurements of housed and grazing goats were recorded at 06.00 h and 14.00 h for 5 consecutive days in each season. Goats were fixed with a face mask and meteorological balloon for collection of expired air and measurement of EE. Respiration rate (RR) at 06.00 h was similar in all seasons (14 respiration/min) except in the monsoon, where a significantly (P<0.05) higher value (26 respiration/min) was recorded. At 14.00 h, RR was higher in monsoon and summer (81 and 91 respiration/min) than in winter (52 respiration/min). Irrespective of the season, heart rate (HR) was higher at 14.00 h (86 beat/min) than at 06.00 h (64 beat/min). The rise of rectal temperature (RT) from morning (06.00 h) to peak daily temperature (14.00 h) was 0.9 °C in housed goats in autumn and 1.0, 2.1 and 2.0 °C in grazing goats during monsoon, winter and summer, respectively. The mean value was 1.7 °C. Skin temperature (ST) was lowest in winter (30.1 °C) and highest at 14.00 h in summer (40.3 °C). Energy expenditure of goats at 06.00 h was 32.7 W in winter and significantly (P<0.05) increased to 52.0 W in summer and 107.8 W in monsoon. At 14.00 h, EE was 140.2 W in winter and increased to 389.0 W and 391.3 W respectively in monsoon and summer. It is concluded that monsoon and summer are both stressful seasons in semi-arid regions. Animals should be protected from direct solar radiation during the hottest hours of the day to ameliorate the effect of heat stress.
Effects of spray application of urea fertilizer at stem extension on winter wheat: N recovery and nitrate leaching
Authors: READMAN R. J. , BECKWITH C. P. , KETTLEWELL P. S. 
Published: October 2002

A field experiment was carried out at Harper Adams in Shropshire to investigate the effect of supplying the spring N application to winter wheat as different proportions of urea as a solution, rather than as conventional soil-applied solid urea, on N recovery in the above-ground crop, autumn soil mineral N and nitrate leaching over the subsequent winter. A solid ammonium nitrate treatment was also included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. N recovery was measured in all 3 years by difference in N uptake between fertilized and unfertilized plots, and in 1993 for selected treatments, N was applied as 15N-labelled fertilizer to determine direct uptake of fertilizer N in the crop and soil. Both urea sprays and solid soil N applications were labelled with 15N. Urea sprays were split over several days to reduce scorch, whereas solid fertilizer was applied as a single dressing. For some urea spray treatments, apparent N recovery in the above-ground crop in 1992 and 1994 was less compared with soil-applied N treatments. These urea spray treatments were applied in the morning rather than the evening, and gaseous losses, most likely by volatilization, are suggested. In 1992 application of a large proportion of N as urea sprays, such that application of some N as urea solution was delayed to around GS 37, was associated with an increase in physiological N use efficiency. In 1993, there was no difference in direct or apparent recovery of fertilizer N in the crop or soil for N applied as ammonium nitrate, solid urea or as urea sprays. Mean nitrate concentration in the drainage water at 1 m was elevated for all N treatments in all years, but only in 1992 did nitrate concentration and leaching loss decrease with increasing proportion of N applied as urea sprays. It may therefore be possible to reduce gaseous losses by application of urea sprays under cool conditions in the evening and exploit the increased physiological N use efficiency for urea sprays applied later, such that total fertilizer N applied and N losses are reduced.
The merger of vertically offset
quasi-geostrophic vortices
Authors: REINAUD J. N. , DRITSCHEL D. G. 
Published: October 2002

We examine the critical merging distance between two equal-volume, equal-potential-
vorticity quasi-geostrophic vortices. We focus on how this distance depends on the
vertical offset between the two vortices, each having a unit mean height-to-width
aspect ratio. The vertical direction is special in the quasi-geostrophic model (used to
capture the leading-order dynamical features of stably stratified and rapidly rotating
geophysical flows) since vertical advection is absent. Nevertheless vortex merger may
still occur by horizontal advection.In this paper, we first investigate the equilibrium states for the two vortices as a
function of their vertical and horizontal separation. We examine their basic properties
together with their linear stability. These findings are next compared to numerical
simulations of the nonlinear evolution of two spheres of potential vorticity. Three
different regimes of interaction are identified, depending on the vertical offset. For
a small offset, the interaction differs little from the case when the two vortices are
horizontally aligned. On the other hand, when the vertical offset is comparable to
the mean vortex radius, strong interaction occurs for greater horizontal gaps than
in the horizontally aligned case, and therefore at significantly greater full separation
distances. This perhaps surprising result is consistent with the linear stability analysis
and appears to be a consequence of the anisotropy of the quasi-geostrophic equations.
Finally, for large vertical offsets, vortex merger results in the formation of a metastable tilted dumbbell vortex.
Spatial distribution of a deep‐sea crinoid Pentametrocrinus tuberculatus in the Izu‐Ogasawara Arc, western Pacific
Authors: Tokeshi M. 
Published: October 2002

AbstractSpatial distribution of a deep‐sea crinoid Pentametrocrinus tuberculatus was investigated in the Izu‐Ogasawara Arc, western Pacific. Photographic and video recordings coupled with direct visual observations were conducted from the manned submersible Shinkai 2000 between the depths of 1340 and 1840 m on the south‐western slope of the An'ei Seamount (29° 15′N, 138° 37′E). Close to the seabed, temperature, salinity and dissolved oxygen concentration were in the range of 2.2–3.1 °C, 34.38–34.52 and 1.40–2.15 ml l−1, respectively, and the bottom substratum consisted mainly of flat‐surfaced lava rocks covered by thin manganese oxide crusts. Pentametrocrinus tuberculatus individuals were attached to the surface of lava rocks with their five arms extended horizontally and showed no recognizable movement. Incidence of arm loss (which may indicate mechanical damage or predation pressure) was very low. The highest density of P. tuberculatus occurred in an area termed ‘terrace’ where the slope was reduced above a relatively steep hillside. Analysis of nearest neighbour distances showed that P. tuberculatus individuals generally demonstrate regular spacing with either no or partial overlap of their ambits (= circular area defined by the extended arms), due to a combination of aggregative tendency (to form patches) and behavioural spacing among individuals within a patch. The observed pattern of distribution was clearly different from the pattern expected from random occurrence of individuals in space. Thus, on spatial scales of 101 to 103 m, P. tuberculatus showed a contagious or aggregated distribution, while on smaller scales and in areas where crinoids were concentrated they showed a combination of patch formation and regular distribution of individuals.
Biased geographical distribution of mitochondrial DNA that passed the species barrier from mountain hares to brown hares (genusLepus): an effect of genetic incompatibility and mating behaviour?
Authors: Thulin Carl‐Gustaf , Tegelström Håkan 
Published: October 2002

AbstractThrough interspecific hybridization and subsequent backcrossing, genes and genomes may be transferred over the species barrier. In Sweden, the introduced brown hareLepus europaeushybridizes with the native mountain hareL. timidus. To investigate the direction and the extent of transfer of mitochondrial DNA (mtDNA) between the species, the mtDNA haplotypes were screened in 522 brown hares and 149 mountain hares from areas of sympatry and allopatry. A total of 51 brown hares with mountain hare mtDNA, but no mountain hares with brown hare mtDNA were detected. Thus, mtDNA transfer over the species barrier is directed from mountain hares to brown hares. We argue that frequency‐dependent hybridization and/or interspecific male competition mediates this directionality. Further, the percentage of brown hares with transmitted mountain hare mtDNA was lower in areas of former species sympatry (0.6%) compared to areas of current sympatry (15%). Thus, the transferred mtDNA may disappear from brown hare populations if there is no continuous input through hybridization. We suggest that specimens with an alien mtDNA experience a fitness reduction as a result of a functional incompatibility between the cytoplasmic mitochondrial genomes and the cell nucleus.
Extraordinary life spans of naked mole‐rats (Heterocephalus glaber)
Authors: Sherman Paul W. , Jarvis Jennifer U. M. 
Published: October 2002

AbstractSenescence is the internal physiological deterioration that accompanies advancing age. Evolutionary hypotheses predict that rates of senescence should vary directly with extrinsic mortality and inversely with fecundity. If so, naked mole‐rats (Heterocephalus glaber) should live a long time (senesce slowly) because in nature they inhabit heavily protected burrows, and large, old breeding females make disproportionate reproductive contributions. In addition H. glaber has an exceptionally low metabolic rate, which may reduce oxidative stress. We have maintained naked mole‐rats in captivity since 1974. Here we report that individuals can live a very long time: many are alive after more than 20 years and some are 26 years old (and counting). Although we do not yet know how long naked mole‐rats can live, they already are older than the maximum longevity of all but one of 156 rodent species that have been maintained in captivity from birth to death.
Short‐term movements and habitat use of the marsupial honey possum (Tarsipes rostratus)
Authors: Bradshaw S. D. , Bradshaw F. J. 
Published: October 2002

AbstractMiniature radio‐transmitters were used to follow movements over a 10‐day period of the 10 g honey possum Tarsipes rostratus, and the areas covered were compared with home‐range estimates calculated from long‐term mark‐and‐recapture records using pitfall traps. The study was carried out in the Scott National Park, in the extreme south‐west of Western Australia, and shows that honey possums may move far greater distances than is apparent from trapping records. The overall mean area used determined by radio‐tracking was significantly larger at 0.54±0.19 ha than the apparent home range of 0.03 0.01 ha determined by trapping. The area used by males was significantly greater than that of females when measured by radio‐telemetry (0.79±0.24 ha vs 0.14±0.08 ha, P= 0.058), but did not differ significantly when estimated from trapping records (0.03±0.01 ha vs 0.01±0.01 ha). These data suggest that honey possums frequent plant assemblages at night where they are vulnerable to pitfall trapping, but that males, particularly, spend the day in other areas that may be as far as 200 m distant.
Seasonal and spatial variation in the diet of the wild rabbit (Oryctolagus cuniculus L.) in Portugal
Authors: Martins H. , Milne J. A. , Rego F. 
Published: October 2002

AbstractThe seasonal and spatial pattern of diet composition of a population of wild rabbits Oryctolagus cuniculus L. occupying a southern Portuguese montado was estimated using the n‐alkane technique. The diet was analysed in terms of components that are relevant to habitat management. The dietary categories considered were gum cistus leaves and flowers, cork oak and holm oak seedlings and acorns, cereals, olive tree regrowth and grass‐forb species. The objectives were to assess the changes in diet across seasons in relation to the reproductive cycle of the rabbits, and to relate these changes to herbaceous biomass availability and to habitat structure, in terms of density of scrub cover and accessibility to arable crops. The results demonstrated that the diet was dominated by grass‐forbs, and cereals when they were available. Browse was an important component of the diet and became more important in a year of low herbaceous biomass availability and in areas dominated by dense scrub. A similar phenomenon was observed in relation to consumption of acorns in winter. Seasonal and spatial variation in diet composition suggested a strategy aimed at maintaining a high quality diet. This was supported by the observed high dry matter digestibility of the diet during most of the year. The relevance of growing arable crops and providing fodder, as a means of increasing the carrying capacity of montados for rabbits and protecting the natural regeneration of trees, is discussed.
Wren and the development of structural carpentry 1660–1710
Authors: Campbell James W. P. 
Published: October 2002

The late seventeenth century saw massive shifts in construction
techniques and practice. This was particularly true in structural
carpentry and owed much to the innovations of a single architect.Sir Christopher Wren occupies a central place in
English architectural history. Yet he was also a
mathematician and it is reasonable to assume
that he took more than a passing interest in the
structural aspects of his buildings. Starting from the
work of David Yeomans (1992 et al), this article
considers his involvement in one particular craft,
carpentry. By returning to the original documents
and from careful measurement and recording of the
surviving works and other buildings of the time, it
reveals that his office had a far greater influence
than hitherto supposed.