bluuebunny/crossref_metadata_2025 huggingface dataset:
The adaptation of soleus and edl in a rat model of distraction osteogenesis: IGF‐1 and fibrosis
Authors: De Deyne P. G. , Kinsey S. , Yoshino S. , Jensen‐Vick K.
Published: October 2002

The distraction rate of 0.5 mm/day produces good osteogenesis in small rodents; however, the effects of this distraction rate on muscle are not well documented. We evaluated the soleus and the extensor digitorum longus (EDL) after two weeks of lengthening distraction osteogenesis (DO) at 0.5 mm/day in skeletally mature rats. We found a modest but significant local increase of insulin like growth factor‐1 (IGF‐1) in the EDL, however, muscle growth indicated by developmental forms of myosin heavy chain (MHC) was not detected by mRNA (RT‐PCR). To the contrary, the data suggested a decrease in cross‐sectional area of the muscle fibers as well as a decrease in mRNA for slow MHC. Immunolabeling of fibronectin in cryosections of the EDL indicated fibrosis of the perimuscular connective tissue while assessment of the passive joint motion did not suggest a lack of excursion on the part of the dorsal flexors. While the literature suggests that IGF‐1 facilitates muscle growth especially in young animals, excess of IGF‐1 in muscle from adults may exacerbate DO‐induced fibrosis.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
High‐pressure pulsatile lavage irrigation of contaminated fractures: effects on fracture healing
Authors: Caprise Peter A. , Miclau Theodore , Dahners Laurence E. , Dirschl Douglas R.
Published: October 2002

To evaluate the effects of high‐pressure pulsatile lavage (HPPL) irrigation on new bone formation and fracture union in a contaminated intraarticular fracture, 45 New Zealand white rabbits were divided into three equal groups. The control group (C) underwent an osteotomy of the medial femoral condyle, contamination with a slurry of clay mixed with Staphylococcus aureus, stabilization and closure. The bulb syringe and pulsatile groups (B and P) underwent an identical procedure, with the addition of irrigation with 1 1 of saline by bulb syringe or pulsatile lavage system. Two fluorescent bone stains that mark new bone formation were administered subcutaneously: xylenol orange at the time of surgery and calcein green one week postoperatively. Animals were euthanized two weeks postoperatively and femurs were retrieved for histological analysis. Union was determined by examination of microradiographs. The viability of bone along the osteotomy site in the first and second weeks after irrigation was determined by evaluation of the two fluorescent stains. The density of new bone two weeks after irrigation was assessed by digitization of the microradiographs. Nonunion was present in 77%, 53%, and 43% of animals in groups C, B, and P, respectively. There was an increase in the presence of bands of both fluorescent stains along the osteotomy site in the groups B and P compared to group C. There was no statistically significant difference between groups B and P in either fluorescent stain. On digitization of microradiographs, there was more calcified new bone on postoperative day 14 in group P than in either group B or C (p = 0.04). The addition of contamination and foreign material to an intraarticular fracture model results in lower rates of new bone formation and fracture union. Irrigation in this setting is clearly beneficial, whether the irrigant is delivered by bulb irrigation or by HPPL. The results of this study indicate using HPPL in this setting does not cause greater damage than using bulb syringe irrigation.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Transplanted bone marrow cells localize to fracture callus in a mouse model
Authors: Devine Michael J. , Mierisch Cay M. , Jang Euichan , Anderson Peggy C. , Balian Gary
Published: October 2002

Bone marrow contains many cellular elements that may contribute to fracture repair. We used a pluripotential stromal cell in a mouse model to demonstrate the presence of transplanted cells in fracture hematoma and subsequently in maturing fracture callus. Cells were transduced with traceable genes (lac Z and neomycin resistance) and traced in vivo after intravenous injection into syngeneic mice. These transduced cells home to bone marrow, suggesting that they might be detected in fracture callus.

Cells were injected intravenously into mice and stabilized femoral shaft fractures were induced. Control mice received intravenous lactated‐Ringer's solution prior to fracture. Callus tissue and marrow were examined histologically from 1 to 10 weeks after fracture to detect transplanted cells. Transplanted cells were detected in fracture callus in areas, and at times, of most active bone formation. Control specimens showed minimal staining of the callus tissue. Levels of the traceable gene in fracture callus increased, reached a peak between 3 and 4 weeks after fracture, then diminished and disappeared by 10 weeks post‐fracture as woven bone at the fracture site was replaced by lamellar bone with cells from the host mouse. The results show that pluripotent bone marrow cells home to the marrow after systemic injection and localize in fracture callus.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
A potential mechanism for age‐related declines in patellar tendon biomechanics
Authors: Dressler M. R. , Butler D. L. , Wenstrup R. , Awad H. A. , Smith F. , Boivin G. P.
Published: October 2002

Injuries to soft tissues such as tendons are becoming ever more frequent among the elderly. While increasing levels of activity likely contribute to these injuries, age‐related declines in tendon strength may also be important. Whether these declines in bio‐mechanical properties are associated with changes in fibril diameter or collagen type remains in question. In this study, age‐related changes were investigated in patellar tendons from young adult rabbits (1‐year old, n = 17) and from rabbits at the onset of senescence (4‐year old, n = 33). Patellar tendon biomechanics was correlated with both collagen fibril diameter and with the presence of type V collagen, a known regulator of collagen fibril diameter. We hypothesize that (a) aging from 1 to 4 years results in significant reductions in patellar tendon biomechanical properties, and (b) these age‐related declines are associated with smaller fibril diameters and with the presence of type V collagen. Maximum stress declined 25% between 1 and 4 years of age (100.7 ± 5.6 MPa and 74.3 ± 3.4 MPa, respectively, p < 0.0003) (mean ± SEM) and strain energy density declined 40% (p < 0.001). The distribution of collagen fibrils from 4‐year old rabbits was skewed significantly towards smaller diameters compared to fibrils from 1‐year old rabbits (p < 0.001). Type V collagen was observed only in the 4‐year old rabbit tendons. These correlations suggest that with increasing age after skeletal maturity, type V collagen may help to regulate the assembly and thus diameter of collagen fibrils and thereby adversely affect patellar tendon strength.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Thoracolumbar spine mechanics contrasted under compression and shear loading
Authors: Frei Hanspeter , Oxland Thomas R. , Nolte Lutz‐P.
Published: October 2002

The mechanical properties of the human spine have been studied extensively in compression, but there remains a lack of fundamental data in shear. The overall goal of this study was to contrast the mechanics of the thoracolumbar functional spinal unit (FSU) under compression and shear‐type loads by evaluating endplate deformation, disc pressures, and kinematics between the different loading types. Eleven T12‐L1 and one L1‐L2 human FSUs were tested. Compression loads consisted of pure compression, extension‐compression, flexion‐compression, lateral left and right compression applied individually to a maximum of 500 N. Shear loading consisted of posterior, anterior, left, and right shear to a maximum of 500 N. Intervertebral motions, disc pressure, and vertebral body deformations were recorded for all loads. The deformations were measured using strain gauge rosettes at three points on the inferior vertebral body and one on the superior endplate of the inferior vertebra. The disc pressures and endplate deformations measured were significantly less in shear loading compared to compression and did not change significantly with the type of compression load. Vertebral rim strains were generally greater under shear loading compared with compression. The mechanics of load transfer in compression was the production of high disc pressures which were not linearly correlated with the central endplate deformation. In shear, the mechanism appears to be via the annulus fibrosus without the development of significant disc pressure. These differences between compression and shear loading may have implications for injury mechanisms in the thoracolumbar spine.
Effect of irrigation solutions for arthroscopic surgery on intraarticular tissue: Comparison in human meniscus‐derived primary cell culture between lactate Ringer's solution and saline solution
Authors: Shinjo Hirotaka , Nakata Ken , Shino Konsei , Hamada Masayuki , Nakamura Norimasa , Mae Tatsuo , Miyama Takahide , Horibe Shuji , Yoshikawa Hideki , Ochi Takahiro
Published: October 2002

In order to determine whether there is a difference in effect on cell morphology and function between two common arthroscopic irrigation solutions, primary cultures of cells derived from the surgically excised human menisci were incubated for 3 or 6 h in lactated Ringer's solution, isotonic sodium chloride solution, or serum‐free cell culture medium (negative‐control condition). Cell integrity was blindly evaluated by three independent examiners scoring photomicrographs of the cell cultures on a battery of five‐point scales for abnormality of cell shape, irregularity of cell membrane, change of cell size and cell density. Cell cultures were also quantitatively assayed by semi‐quantitative reverse‐transcription‐polymerase‐chain‐reaction for mRNA of α1 (I) procollagen, α1 (II) procollagen, aggrecan and heat‐shock protein 70 to assess functional consequences of exposure to the solutions. There was a statistically significant difference in cell integrity scores between either lactated Ringer's solution or serum‐free cell‐culture medium and isotonic sodium chloride solution with greater damage to cells displayed. Scores for lactated Ringer's solution did not differ from those for serum‐free cell‐culture medium. There were no significant differences in mRNA expression level among the treatment conditions. It was concluded that the lactated Ringer's solution better maintained human meniscus cell integrity than the isotonic saline.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Increased content of type III collagen at the rupture site of human Achilles tendon
Authors: Eriksen Heidi A. , Pajala Ari , Leppilahti Juhana , Risteli Juha
Published: October 2002

We compared the type I and III collagen amounts and cross‐linked telopeptides at the rupture site and two other sites of the same tendon. Tendon samples of ten individuals with total Achilles tendon rupture and six healthy cadavers were collected. The newly synthesized type I and III procollagens were assessed by extracting the soluble propeptides PINP, PICP and PIIINP. The insoluble matrix was solubilized by heat denaturation and trypsin digestion. Hydroxyproline, the cross‐linked telopeptide structures of type I (ICTP and SP 4) and III collagens (IIINTP) and the degradation product of type III collagen (tryptic PIIINP) were measured from the digests.

The type III collagen content was significantly increased at the rupture site when compared to control sites (5‐ and 12‐fold increased) or cadavers (5‐fold increased). No changes in the amounts of newly synthesized type I and III procollagens were observed. The ICTP content decreased and the SP 4/ICTP ratio increased along with ageing, suggesting a structural change in the type of cross‐link in the carboxyterminal telopeptide of type I collagen.

Type III collagen has accumulated at the rupture site probably due to microtraumas and the subsequent healing process. The increased content of type III collagen can cause thinner collagen fibers, decrease the tensile strength and may finally result in total rupture of the tendon. The age‐related change in the nature of the cross‐link in the carboxyterminal telopeptide may contribute to this weakening.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effect of repeated irrigation and debridement on fracture healing in an animal model
Authors: Park Sang‐Hyun , Silva Mauricio , Bahk Won‐Jong , McKellop Harry , Lieberman Jay R.
Published: October 2002

The initial management of open fractures often requires repeated irrigation and debridement of the open wound and stabilization of the fracture. However, washing out the fracture hematoma could delay the early healing process of stable fractures. Because delayed union and non‐union are serious complications, the effect of repeated irrigation and debridement on the fracture healing process was investigated.

Twenty‐four rabbits received unilateral, transverse, mid‐tibial open osteotomies with a 3 mm gap. The osteotomy site was thoroughly irrigated and stabilized with double‐bar external fixators. The osteotomy sites in the study groups underwent repeat irrigation and debridement on either the third day (Group II), the fourth day (Group III), or consecutively on the first and second days (Group IV) after the index procedure. The bone healing was assessed with weekly radiographs and peripheral quantitative computerized tomographs.

In Group I (control), all osteotomies healed radiographically before the tenth week. In Group II, five out of six osteotomies healed radiographically before the tenth week. In Group III, only two of five osteotomies healed before the tenth week. In Group IV, none of the osteotomies had healed by week fifteen. All of the non‐healed osteotomies exhibited atrophic non‐unions at fifteen weeks. Compared to the control group at the tenth week, the average bone mineral content at the osteotomy site and the area of high mineral density callus (≥ 890 mg/cm3) were significantly lower in Groups III (63%, p = 0.002 and 95%, p = 0.05, respectively) and IV (99%, p < 0.001 and 100%, p = 0.05, respectively).

The results of this study suggest that repeated irrigation and debridement, associated with persistent rigid immobilization, may contribute to the development of delayed unions or atrophic non‐unions.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Postnatal development of parvalbumin and calbindin D‐28k immunoreactivities in the canine anterior cingulate cortex: transient expression in layer V pyramidal cells
Authors: Moon Jeong Seok , Kim Jong Joong , Chang In Youb , Chung Yoon Young , Jun Jae Yeoul , You Ho Jin , Yoon Sang Pil
Published: October 2002

We have examined the ontogeny of parvalbumin (PV) and calbindin D‐28k (CB) immunoreactivities in the canine anterior cingulate cortex (ACC) from the day of birth (P0) through P180. At P7, PV immunoreactivity first appeared in layer VI multipolar cells. The PV immunoreactivity in GABAergic nonpyramidal cells appeared to follow an inside‐out gradient of radial emergence. Although immunoreaction was limited mainly to the developing nonpyramidal cells, pyramid‐like PV immunoreactive cells were transitorily observed in layer V from P14 to P90. The developmental pattern of CB immunoreactivity differed from that of PV immunoreactivity. CB immunoreactivity first developed in layer V pyramidal cells from P0, which continued through P90. CB immunoreactive nonpyramidal cells were located in the infragranular layers and white matter at P0 and maturated in both the supragranular and infragranular layers without clear inside‐out gradient.

This developmental study revealed the comparable belated expression of PV immunoreactivity and the transient expression of both calcium‐binding proteins in layer V pyramidal cells. These results suggest that the transient expression of calcium‐binding proteins in layer V pyramidal cells might be related to the critical period of early postnatal development.
Postnatal histogenesis in the peripheral nervous system
Authors: Geuna Stefano , Borrione Paolo , Filogamo Guido
Published: October 2002

The issue of postnatal neurogenesis has gained great importance over the last few years and the recent amazing scientific advancements, changing our viewpoint on the long‐lasting “no new neurons” dogma, have opened promising new perspectives on the treatment of the damaged nervous system. While most of the researchers have focused on the central nervous system, the peripheral nervous system has received little attention so far with respect to postnatal histogenesis. To attract scientific attention on this issue, the present article was written with the aim of reviewing the body of literature on postnatal histogenesis in the various districts of the peripheral nervous system, from the historical roots to the most recent reports.
DNA‐polymerase α, β, δ and ε activities in isolated neuronal and astroglial cell fractions from developing and aging rat cerebral cortex
Authors: Raji N.S. , Hari Krishna T. , Rao Kalluri Subba
Published: October 2002

The relative proportions of DNA‐polymerases α, β, δ and ε (pols α, β, δ and ε) activities in isolated neuronal and astroglial cell fractions from developing, adult and aging rat brain cerebral cortex, were examined. This was achieved through a protocol that takes advantage of the reported differential sensitivities of different DNA‐polymerases towards certain inhibitors like butylphenyl and butylanilino nucleotide analogs, 2′,3′‐dideoxythymidine triphosphate (ddTTP), monoclonal antibody of human α polymerase and the use of two template primers as substrates. The results indicate that while DNA‐polymerase β (pol β) is the predominant enzyme, significant levels of DNA‐polymerases α and δ/ε (pols α and δ/ε) are also present in both cell types at all the post‐natal ages studied. A notable difference regarding the relative abundance of DNA‐polymerases other than β is the higher percentage of pol δ/ε in neurons and a more sustained pol α activity through the life span in astroglia. The presence of detectable proportion of DNA‐polymerases other than β (particularly the δ/ε type) may be taken to indicate their role in long patch base excision repair as well as in other modes of DNA repair.
Analysis and synthesis in John Playfair's Elements of Geometry
Authors: ACKERBERG-HASTINGS AMY
Published: October 2002

John Playfair (1748–1819), professor of mathematics and natural philosophy at the University of Edinburgh, is a relatively obscure figure today, best known as the popularizer of James Hutton's theory of geology. However, Playfair was also involved in mathematics for most of his active career, with his most widely distributed publication, Elements of Geometry (1795), shaping the mathematics education for at least thirteen thousand British students during the nineteenth century. This study focuses on the mathematical context surrounding Elements of Geometry. Specifically, after recounting the background of the text, the paper explores the ways in which Playfair's presentation of elementary geometry reflected three understandings of the terms ‘analysis’ and ‘synthesis’, which were intrinsic components of mathematical culture at the turn of the nineteenth century. In one sense, the words denoted differing styles of mathematical practice in Great Britain and in France. In a second sense, the terms evoked contemporary appeals to ancient methods of proof. Finally, ‘analysis’ and ‘synthesis’ were understood in reference to separate approaches to mathematics education. Playfair's appeals to these understandings help reveal how he viewed himself as a mathematician. Overall, then, this study enriches the standard portrait of a professor who straddled the eighteenth and nineteenth centuries.
Political and Social Trends in the Post-Deng Urban China: Crisis or Stability?
Authors: Tang Wenfang
Published: October 2002

This article uses a 1999 six-city survey of Chinese urban residents, along with several earlier public opinion surveys, in order to compare views on regime legitimacy between Deng and post-Deng eras. Posing the broad question of whether China's regime is seen to be in crisis or increasing stability, the author analyses data to measure public opinion in the areas of reform satisfaction, political support and political efficacy. The data reveals elements of both scenarios, possibly suggesting that the leadership was doing a good job at deepening economic reforms while successfully silencing public dissatisfaction at both the pace and content of market reform policies. Unlike in 1989, when urban residents took their issues to the street, in 1999 they became more politically conservative, even when dissatisfied with reform. Together with their heavy-handed control, the post-Deng leaders seemed to be successful in consolidating political power, using nationalism as an appeal while pushing for further market reform.
Reaching Out and Incorporating Chinese Overseas: The Trans-territorial Scope of the PRC by the End of the 20th Century
Authors: Thunø Mette
Published: October 2002

Examining the policies of the PRC towards Chinese overseas, this paper argues that since the 1990s China has been actively extending its territorial reach to encompass Chinese living outside the sovereignty of the Chinese state. Gradual changes in conceptions and methods to establish allegiances and attract increased financial investments and remittances have re-configured the Chinese state's relationships to Chinese living overseas. By analysing official documents, and through interviews with officials in Fujian (1998–2000), the author identifies two major political shifts in conceptualization. The first appeared in the late 1970s when Chinese citizens living mainly in South-East Asia were again recognized as an important source of revenue to China. A decade later, new policies were introduced appealing to ethnic Chinese and “new migrants” who had left China after 1978. It is discussed how this political adjustment fundamentally transformed the approach towards the Chinese overseas from passive anticipation of being able to gain resources to active state liaison with ethnic Chinese by calling upon their cultural and national loyalties to China.
DIAGONALS IN TENSOR PRODUCTS OF OPERATOR ALGEBRAS
Authors: Paulsen Vern I. , Smith Roger R.
Published: October 2002

In this paper we give a short, direct proof, using only properties of the Haagerup tensor product, that if an operator algebra $A$ possesses a diagonal in the Haagerup tensor product of $A$ with itself, then $A$ must be isomorphic to a finite-dimensional $C^*$-algebra. Consequently, for operator algebras, the first Hochschild cohomology group $H^1(A,X)=0$ for every bounded, Banach $A$-bimodule $X$, if and only if $A$ is isomorphic to a finite-dimensional $C^*$-algebra.

AMS 2000 Mathematics subject classification: Primary 46L06. Secondary 46L05
THE COMPONENT NUMBER OF LINKS FROM GRAPHS
Authors: Mphako Eunice Gogo
Published: October 2002

This paper gives a number which is used to determine the component number of links from their associated planar graphs. In particular, we use this number to determine the component numbers of links whose associated planar graphs are fans, wheels and 2-sums of graphs.

AMS 2000 Mathematics subject classification: Primary 05C10
RIGHT-DEFINITE MULTIPARAMETER STURM–LIOUVILLE PROBLEMS WITH EIGENPARAMETER-DEPENDENT BOUNDARY CONDITIONS
Authors: Bhattacharyya Tirthankar , Ko$\breve{s}$ir Toma$\breve{z}$ , Plestenjak Bor
Published: October 2002

We study a system of ordinary differential equations linked by parameters and subject to boundary conditions depending on parameters. We assume certain definiteness conditions on the coefficient functions and on the boundary conditions that yield, in the corresponding abstract setting, a right-definite case. We give results on location of the eigenvalues and oscillation of the eigenfunctions.

AMS 2000 Mathematics subject classification: Primary 34B08; 34B24
COMBINATORIAL TECHNIQUES FOR DETERMINING RANK AND IDEMPOTENT RANK OF CERTAIN FINITE SEMIGROUPS
Authors: Levi Inessa , Seif Steve
Published: October 2002

Let $\tau$ be a partition of the positive integer $n$. A partition of the set $\{1,2,\dots,n\}$ is said to be of type $\tau$ if the sizes of its classes form the partition $\tau$ of $n$. It is known that the semigroup $S(\tau)$, generated by all the transformations with kernels of type $\tau$, is idempotent generated. When $\tau$ has a unique non-singleton class of size $d$, the difficult Middle Levels Conjecture of combinatorics obstructs the application of known techniques for determining the rank and idempotent rank of $S(\tau)$. We further develop existing techniques, associating with a subset $U$ of the set of all idempotents of $S(\tau)$ with kernels of type $\tau$ a directed graph $D(U)$; the directed graph $D(U)$ is strongly connected if and only if $U$ is a generating set for $S(\tau)$, a result which leads to a proof if the fact that the rank and the idempotent rank of $S(\tau)$ are both equal to

$$ \max\biggl\{\binom{n}{d},\binom{n}{d+1}\biggr\}. $$

AMS 2000 Mathematics subject classification: Primary 20M20; 05A18; 05A17; 05C20
GROUPS WITH THE MAXIMAL CONDITION ON NON-BFC SUBGROUPS. II
Authors: Dixon Martyn R. , Kurdachenko Leonid A.
Published: October 2002

A group $G$ is called a group with boundedly finite conjugacy classes (or a BFC-group) if $G$ is finite-by-abelian. A group $G$ satisfies the maximal condition on non-BFC-subgroups if every ascending chain of non-BFC-subgroups terminates in finitely many steps. In this paper the authors obtain the structure of finitely generated soluble-by-finite groups with the maximal condition on non-BFC subgroups.

AMS 2000 Mathematics subject classification: Primary 20E15. Secondary 20F16; 20F24
The effects of the genotype by environmental interaction on the fixation of heterosis in tomato
Authors: CHRISTAKIS P. A. , FASOULAS A. C.
Published: October 2002

Continuous honeycomb selection and testing in the absence of competition in a single environment, resulted in the isolation of recombinant inbreds in tomato that outperformed the hybrid only in that particular environment. Alternating selection and testing in two environments (open field v. glasshouse) reduced selection efficiency, by preventing exploitation of the whole constellation of genes contributing to heterosis. Selection in the F2 generation was most critical, as evidenced by the appearance of recombinant lines outperforming the hybrid as early as in the F3 generation. Exploitable genetic variation existed in advanced generations and even after the point of achieving theoretical homozygosity (F7 generation). In the future, and in order to fully exploit the unique possibilities offered by the honeycomb methodology (control of soil heterogeneity, high selection pressures, crop yield components), selection for reduced GE interaction should be practiced simultaneously over the target environments of adaptation.
Inheritance of resistance to Mal de Río Cuarto (MRC) disease in Zea mays (L.)
Authors: DI RENZO M. A. , BONAMICO N. C. , DÍAZ D. D. , SALERNO J. C. , IBAÑEZ M. M. , GESUMARIA J. J.
Published: October 2002

No genetic estimates for resistance to Mal de Río Cuarto (MRC) disease in Zea mays (L.) are currently available in the literature. Therefore, the objectives of this investigation were (i) to estimate the variance and heritability of partial resistance to MRC disease and of other agronomic traits from maize families and (ii) to examine associations among MRC disease severity values across different environments and between MRC and other agronomic traits. These estimations, obtained in an endemic area, could contribute to the design of efficient enhancement programmes and evaluation activity for the improvement of MRC resistance. The research was conducted by testing 227 F3 derived-lines from a cross between a susceptible dent line, Mo17, and a partially resistant flint line, BLS14, for MRC disease at two Río Cuarto locations in each of 2 years. The resistance of the lines, measured with a disease severity index (DSI), was normally distributed across environments. Genotypic variances were highly significant on all scoring environments. Estimates of genotype–environment interaction were also significant, suggesting that certain genotypes have little stability over different environments. For disease severity index all estimates demonstrated moderate heritabilities ranging from 0.44 to 0.56 and were similar when based on individual environments or across environment. Confidence interval widths ranged from 34.88 to 50.30% as large as the heritability point estimate. The correlations between environments were small enough to indicate that families did not rank similarly in individual environments for MRC resistance. Disease severity index correlated significantly (P<0.01) with plant height, leaf surface, leaf border, leaf length and tassel type. Heritability estimates for plant height and tassel type were 0.48 and 0.38 respectively and for the various leaf traits heritability values were very low. On the basis of the substantial genotype–environment interaction and the little association between DSI values in the different environments, selection for an increased resistance to MRC disease would require evaluation of germplasm across multiple years and locations. Tassel type would be a useful predictor of DSI and can be used effectively to improve screening procedures.
Factors affecting reproductive performance and estimates of genetic parameters of litter size in Horro sheep
Authors: ABEGAZ S. , DUGUMA G. , NEGUSSIE E. , GELMESA U. , TEREFE F. , REGE J. E. O.
Published: October 2002

Conception and lambing rate, and litter size were studied on data from a flock of Horro sheep. The CATMOD and GLM procedures of SAS were used for the analysis of these traits. A sire, direct additive genetic and a repeatability animal model were employed to obtain estimates of heritability and repeatability for litter size. The results obtained showed that year of mating, age and weight of ewes at mating and number of previous parities had significantly (P<0.01) affected the rate of conception and lambing while weight of rams at mating has shown no significant effect (P>0.05). An increase in both conception and lambing rates was observed with the increase in weight of ewes up to about 36 kg and declined thereafter. Ewes which previously had no or one parity had lower conception and lambing rates compared with ewes in later parities. However, a decline in both conception and lambing rates was also observed in old ewes. Year of lambing, parity and weight of ewes at mating had a highly significant (P<0.01) effect on litter size. The overall mean litter size in the flock was 1.34 with annual means ranging from 1.18 to 1.55. Litter size increased with parity from 1.26 in primiparous ewes to 1.44 for ewes of parities five and above. With respect to weight of ewes at mating, litter size increased by 2.5% for each kg increase in weight at mating. The estimates of direct heritability (h2) for litter size were 0.17, 0.11 and 0.06 under the sire, direct animal and repeatability models. Repeatability was estimated to be 0.12. Since heritability and repeatability estimates of litter size are low, genetic improvement by selection may not bring sizeable impact in increasing litter size. Therefore flock management for optimal age structure and optimal weight of ewes at mating should receive due consideration to improve rates of conception, lambing and litter size in Horro sheep.
The effect of soil acidity on potentially mobile phosphorus in a grassland soil
Authors: MCDOWELL R. W. , BROOKES P. C. , MAHIEU N. , POULTON P. R. , JOHNSTON A. E. , SHARPLEY A. N.
Published: October 2002

This study compared phosphorus (P) speciation and the relationship between bicarbonate extractable (Olsen) P and 0.01 M CaCl2 extractable P (a measure of potentially mobile P) in soils from plots of the Park Grass experiment started in 1856 at IACR-Rothamsted, UK and with and without nitrogen as (NH4)2SO4 and with and without calcium carbonate (CaCO3, lime). A point, termed the change point, was noted in Olsen P, above which 0.01 M CaCl2-P increased at a greater rate per unit increase in Olsen P than below this point. Previous findings have shown a change point for soils with a pH>5.8 at 56 mg Olsen P/kg and at 120 mg Olsen P/kg for soils below this pH. Soils given (NH4)2SO4 annually since 1856 and with lime periodically since 1903 mostly had a pH between 3.7 to 5.7, some of these (NH4)2SO4 treated soils were limed to pH 6.5 and above from 1965. Irrespective of their pH in 1991/92 all the soils had a similar change point (120 mg Olsen P/kg) to that found for other soils with pH<5.8 (112 mg Olsen P/kg). In a laboratory study lasting 30 days, the addition of CaCO3 to acid soils from the field experiment that had received (NH4)2SO4 had a similar change point to soils with pH<5.8 irrespective of pH, suggesting soil P chemistry was controlled by the long period of soil acidity and this was not reversed by a short period at a higher pH. The effect of pH was attributed to the creation of P sorptive surfaces on aluminium precipitates compared with less acidic soils (pH>5.8) where there was less exchangeable Al to be precipitated. This was confirmed with solid-state 31P nuclear magnetic resonance, which indicated that for soils of similar total P concentration and pH, there was twice as much amorphous Al-P in soils given (NH4)2SO4 compared with those without. Changes in pH as a result of applications of (NH4)2SO4 or lime can greatly change the concentration of potentially mobile P due to the effects on Al solubility. Although there was less potentially mobile P in soils with pH<5.8 than in soils above this pH, it is usually advised in temperate regions to maintain soils about pH 6.5 for arable crops.
Boundary layer development on a semi-infinite
suddenly heated vertical plate
Authors: PATTERSON JOHN C. , GRAHAM TASMAN , SCHÖPF WOLFGANG , ARMFIELD S. W.
Published: October 2002

The flow resulting from suddenly heating a semi-infinite, vertical wall immersed in
a stationary fluid has been described in the following way: at any fixed position on
the plate, the flow is initially described as one-dimensional and unsteady, as though
the plate is doubly infinite; at some later time, which depends on the position, a
transition occurs in the flow, known as the leading-edge effect (LEE), and the flow
becomes two-dimensional and steady. The transition is characterized by the presence
of oscillatory behaviour in the flow parameters, and moves with a speed greater than
the maximum fluid velocities present in the boundary layer. A stability analysis of
the one-dimensional boundary layer flow performed by Armfield & Patterson (1992)
showed that the arrival times of the LEE determined by numerical experiment were
predicted well by the speed of the fastest travelling waves arising from a perturbation
of the initial one-dimensional flow. In this paper, we describe an experimental
investigation of the transient behaviour of the boundary layer on a suddenly heated
semi-infinite plate for a range of Rayleigh and Prandtl numbers. The experimental
results confirm that the arrival times of the LEE at specific locations along the plate,
relatively close to the leading edge, are predicted well by the Armfield & Patterson
theory. Further, the periods of the oscillations observed following the LEE are consistent
with the period of the maximally amplified waves calculated from the stability
result. The experiments also confirm the presence of an alternative mechanism for the
transition from one-dimensional to two-dimensional flow, which occurs in advance of
the arrival of the LEE at positions further from the leading edge.
Note on a paper by Robinet, Gressier,
Casalis & Moschetta
Authors: COULOMBEL JEAN-FRANÇOIS , BENZONI-GAVAGE SYLVIE , SERRE DENIS
Published: October 2002

In Robinet et al. (2000), an instability for shock waves in gas dynamics is exhibited.
The fluid was assumed to obey the polytropic perfect gas pressure law. We show in
this note that such an instability does not occur, as proved in the extensive work of
Majda (1983). Two arguments are developed: we give first a mathematical result that
is violated by the conclusions of Robinet et al. (2000). Then we detail the results of
Robinet et al. (2000) and show why they do not yield any conclusions. Finally, we
develop a general calculation and show that an instability cannot occur.
Langmuir circulations beneath growing
or decaying surface waves
Authors: PHILLIPS W. R. C.
Published: October 2002

The instability to longitudinal vortices of two-dimensional density-stratified temporally evolving wavy shear flow is considered. The problem is posited in the context
of Langmuir circulations, LCs, beneath wind-driven surface waves and the instability
mechanism is generalized Craik–Leibovich, either CLg or CL2. Of interest is the
influence of non-stationary base flows on the instability according to linear theory. It
is found that the instability is described by a family of similarity solutions and that the
growth rate of the instability, in non-stationary base flows, is doubly exponential in
time, although the growth rate reduces to exponential when the base flow is stationary.
An example is given for weakly sheared wind-driven flow evolving in the presence of
growing irrotational surface waves. Waves aligned both with the wind and counter
to it are considered, as is the role of stratification. Antecedent to the example is
an initial value problem posed by Leibovich & Paolucci (1981) for neutral waves in
slowly evolving shear. Here, however, the waves and shear may grow (or decay) at
rates comparable with the LCs. Furthermore the current here has two components: a
wind-driven portion due to the wind stress applied at the free surface and a second
due to the diffusion of momentum due to the wave-amplitude-squared free-surface
stress condition. Using the case for neutral waves in non-stratified uniform shear for
reference, it is found, in general, that growing waves are stabilizing while decaying
waves are destabilizing to the formation of LCs, although the latter applies only for
sufficiently large spanwise spacings and is subject to a globally stable lower bound.
Decaying waves in the absence of wind can also be destabilizing to LCs. When the
wind is counter to the waves, however, only decaying waves are unstable to LCs.
Furthermore, while growing waves are stable to the formation of LCs in the presence
of stable stratification, decaying waves are unstable in both aligned and opposed
wind-wave conditions. Unstable stratification on the other hand, is destabilizing to
LCs for all temporal waves in both aligned and opposed wind-wave conditions.
Relationship between the intrinsic radial distribution function for an isotropic field of particles and lower-dimensional measurements
Authors: HOLTZER GRETCHEN L. , COLLINS LANCE R.
Published: October 2002

In this paper, we present relationships between the intrinsic radial distribution
function (RDF) for a three-dimensional, isotropic system of particles and the lower-dimensional
RDFs obtained experimentally from either two-dimensional or one-dimensional
sampling of the data. The lower-dimensional RDFs are shown to be
equivalent to integrals of the three-dimensional function, and as such contain less
information than their three-dimensional counterpart. An important consequence is
that the lower-dimensional RDFs are attenuated at separation distances below the
characteristic length scale of the measurement. In addition, the inverse problem
(calculating the three-dimensional RDF from the lower-dimensional measurements) is
not well posed. However, recent results from direct numerical simulations (Reade
& Collins 2000) showed that the three-dimensional RDF for aerosol particles in a
turbulent flow field obeys a power-law dependence on r for r [Lt ] η,
where η is the Kolmogorov scale of the turbulence. In this case, the inverse problem is well posed
and it is possible to obtain the prefactor and exponent of the power law from one-
or two-dimensional measurements. A procedure for inverting the data is given. All
of the relationships derived in this paper have been validated by data derived from
direct numerical simulations.
Random-sweeping hypothesis for passive scalars in isotropic turbulence
Authors: YEUNG P. K. , SAWFORD BRIAN L.
Published: October 2002

The hypothesis of the small scales being passively swept along by the large-scale motions
in turbulent flow is extended to passive scalars in isotropic turbulence. A theory
based on strong mutual cancellation between local and advective derivatives and other
assumptions is shown to capture the Reynolds and Schmidt number dependence of
time scales characterizing Eulerian and Lagrangian rates of change. Agreement with
direct numerical simulation data improves systematically with increasing Reynolds
number. In accordance with the physics of random sweeping, the Eulerian frequency
spectrum is very similar in shape to the wavenumber spectrum, but is broadened at
higher frequencies compared to its Lagrangian counterpart. Overall the hypothesis
appears to be even more valid for transported scalars than for the velocity field, which
gives support to the use of Lagrangian approaches in the study of turbulent mixing.
Draining viscous gravity currents in a vertical fracture
Authors: PRITCHARD DAVID , HOGG ANDREW J.
Published: October 2002

We consider the flow of instantaneous releases of a finite volume of viscous fluid in a
narrow vertical fracture or Hele-Shaw cell, when there is a still narrower vertical crack
in the horizontal base of the cell. The predominant motion is over the horizontal
surface, but fluid also drains through the crack, progressively diminishing the volume
of the current in the fracture. When the crack is shallow on the scale of the current,
it saturates immediately with the draining fluid. In this case, we obtain an exact
analytical solution for the motion. When the crack is deeper and does not saturate
immediately, we calculate numerically the motion of the fluid in both the fracture
and the crack. In each case the current advances to a finite run-out length and then
retreats: we describe both phases of the motion and characterize the run-out length
in terms of the controlling parameters.
Grassroots Movements and Political Activism in Latin America: A Critical Comparison of Chile and Brazil
Authors: FOWERAKER JOE
Published: October 2002

This essay addresses the changing trajectory of grassroots political activity in Latin America, with special reference to Chile and Brazil, and assesses its impact on the policy and practices of social development. It traces this trajectory through the transitions from authoritarian to democratic rule, and focuses on the responses of grassroots organisations to democratic governance and the rise of neo-liberalism. In particular, it shows that social movements have declined or been transformed (or both), while non-governmental organisations (NGOs) have multiplied and become more visible. It appears that where grassroots organisations interact with the state they may be subordinated to state policy, and where they fail to interact they may be ineffective. Their influence on social development mainly occurs piecemeal through social service delivery, not through the shaping of social policy itself.
Financial Structure and Financing Models: The Brazilian Experience over the 1964–1997 Period
Authors: HERMANN JENNIFER
Published: October 2002

The article analyses the Brazilian experience in financing economic activity from the 1964–67 reform until the 1990s. Two issues are addressed: first, what conditions explain the development of a model based on public and external credit in Brazil, quite different from the capital market based system conceived in the 1964–67 reform? Second, what are the perspectives for the development of an alternative model in the country, led by the national private sector? Based on international experience, two alternatives are considered: a) the expansion of the capital market, in order to make possible large scale direct financing; b) the formation of a private banking credit system, complementing or replacing both public and external credit. Despite undoubted improvements, tendencies observed up to 1997 suggest the persistence of the ‘short-termist’ profile that typically characterised the Brazilian financial system. Thus, the development of both capital market and banking credit models depends on financial policies devoted to this goal. General guidelines for such policies are suggested in the last section of the paper.
The dual status of middle-distance reflexives
Authors: XUE PING , POPOWICH FRED
Published: October 2002

We examine a class of English reflexive pronouns that we call middle-distance reflexives. We show that while not occurring in direct argument positions, middle-distance reflexives can either be syntactically bound or be interpreted according to pragmatic and discourse conditions, suggesting that syntactic reflexives in American English extend beyond direct argument positions. We will also discuss uses of reflexives in British English and Chinese in comparison with those in American English. While these languages demonstrate variations in the distribution of syntactic reflexives and discourse reflexives, the relevant facts indicate that syntactic binding in natural languages may not necessarily be obligatory, and the licensing condition for syntactic reflexives and discourse reflexives is not exclusively disjunctive. Allowing the options of both syntactic binding and discourse coreference for establishing the relation between reflexives and their antecedents is a more general aspect of reflexives, which is consistent with the view proposed in Pollard & Xue 2001.
The decline and conservation management of the threatened endemic palms of the Mascarene Islands
Authors: Maunder Mike , Page Wayne , Mauremootoo John , Payendee Richard , Mungroo Yousoof , Maljkovic Aleks , Vericel Christian , Lyte Ben
Published: October 2002

Abstract The conservation status of the five genera and 11 species of palm endemic to the Mascarene Islands (Mauritius, La Réunion and Rodriques) are reviewed. All species are threatened with extinction; nine taxa are classified as Critically Endangered and four as Endangered on the 2000 IUCN Red List. Two taxa survive as single wild specimens (Hyophorbe amaricaulis and Dictyosperma album var. conjugatum); an additional seven taxa have wild populations of 100 or fewer. Although the historical phase of large-scale forest clearance has passed, the remaining palm populations in the Mascarenes are under threat from the effects of population fragmentation, invasive plants and animals, and high levels of seed predation that prevent natural regeneration. The advantages of in situ management for the recovery of these palm populations are discussed. Without a long-term conservation programme, utilising both in situ and ex situ management, extinction of wild populations will occur.