bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of packaging materials on the dissolved oxygen content of probiotic yoghurt
Authors: Miller Craig W. , Nguyen Minh H. , Rooney Michael , Kailasapathy Kaila
Published: October 2002

The health benefits of probiotic functional foods have been widely reported. However, manufacturers face great challenge in guaranteeing delivering beneficial numbers of viable probiotic bacteria through to the end of the product shelf life. The oxygen toxicity of some probiotic species has been shown to contribute to reduced viable counts. The packaging system favoured by manufacturers may play a negative role, promoting oxygen uptake in the product. The research detailed herein evaluates the performance of current packaging materials and an alternative, oxygen‐barrier material. Commercial stirred‐type probiotic yoghurt was evaluated for dissolved oxygen content over a 6 week period from manufacture to expiry date. The results indicate a rising level of dissolved oxygen in the yoghurts over time. The distribution of oxygen throughout the product was also examined by measuring concentrations in two lateral positions, at three different depths. It was found that oxygen was not distributed homogenously, but was in significantly different concentrations (p < 0.05) at most sampling points. At some locations (near packaging weak spots), readings were approaching saturation, hardly an environment suited to the survival of the anaerobic and probiotic Bifidobacterium species. Yoghurt stored in packaging materials with improved gas‐barrier properties was also tested, displaying a decrease in dissolved oxygen levels during storage. It was concluded that using packaging materials with greater gas‐barrier properties would help remove a hurdle to the viability of the probiotic bacteria within the food. Suggestions for further steps, such as the addition of an oxygen‐scavenging technology, are also made. Copyright © 2002 John Wiley & Sons, Ltd.
Predicting changes in oxygen concentration in the headspace of nitrogen flushed packages by the ambient oxygen ingress rate method
Authors: Larsen Hanne , Kohler Achim , Magnus Ellen Merethe
Published: October 2002

The ambient oxygen ingress rate (AOIR) method is an alternative/supplementary method to Ox‐Tran for measuring the oxygen transmission rates of packages. The AOIR method facilitates high‐capacity testing of packages under realistic food storage conditions, on the one hand, and on the other hand provides the possibility to predict the oxygen concentration over time in packages flushed with nitrogen at the time of packaging. The predicted oxygen concentration values showed good agreement with experimental values for flexible packages stored over a period of 91 days at 23°C and 38°C. The prediction of the oxygen concentration in­nitrogen‐flushed packages may be a useful tool, e.g. in shelf life studies, in the selection of the optimal food package as regards to oxygen protection and within quality control purposes. Copyright © 2002 John Wiley & Sons, Ltd.
Gravure‐printed colour indicators for monitoring Kimchi fermentation as a novel intelligent packaging
Authors: Hong Seok‐In
Published: October 2002

Gravure‐printed colour indicators on common nylon/polyethylene (Ny/PE) films were newly developed for kimchi (fermented vegetable products in Korea) packaging to examine the degree of fermentation of such products non‐destructively during distribution and sale. A printing ink consisting of Ca(OH)2 as a CO2 absorbent, bromocresol purple (BP) or methyl red (MR) as a chemical dye, and a mixture of polyurethane and polyester dissolved in organic solvents as a binding medium, was applied on Ny films by the gravure process and then laminated with PE films to form the printed indicator. During storage at 0, 10, 20°C, kimchi fermentation was assessed for titratable acidity (TA), and the colour of the indicators was determined as Hunter values and expressed as total colour difference (TCD). Although TCD value of the BP type indicator was slightly less than that of the MR type, colour changes in both the types of indicator correlated well to TA values of kimchi. The results suggest that gravure‐printed colour indicators have great potential as an intelligent packaging system for monitoring the ripeness of commercial kimchi products. Copyright © 2002 John Wiley & Sons, Ltd.
Crossing numbers of random graphs
Authors: Spencer Joel , Tóth Géza
Published: October 2002

The crossing number of G is the minimum number of crossing points in any drawing of G. We consider the following two other parameters. The rectilinear crossing number is the minimum number of crossing points in any drawing of G, with straight line segments as edges. The pairwise crossing number of G is the minimum number of pairs of crossing edges over all drawings of G. We prove several results on the expected values of these parameters of a random graph. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 347–358, 2002
Testing subgraphs in large graphs
Authors: Alon Noga
Published: October 2002

LetHbe a fixed graph withhvertices, letGbe a graph onnvertices, and suppose that at least ϵn2edges have to be deleted from it to make itH‐free. It is known that in this caseGcontains at leastf(ϵ,H)nhcopies ofH.We show that the largest possible functionf(ϵ,H) is polynomial in ϵ if and only ifHis bipartite. This implies that there is a one‐sided error property tester for checkingH‐freeness, whose query complexity is polynomial in 1/ϵ,if and only if His bipartite. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 359–370, 2002
Nonrepetitive colorings of graphs
Authors: Alon Noga , Grytczuk Jarosław , Hałuszczak Mariusz , Riordan Oliver
Published: October 2002

A sequence a = a1a2 … an is said to be nonrepetitive if no two adjacent blocks of a are exactly the same. For instance, the sequence 1232321 contains a repetition 2323, while 123132123213 is nonrepetitive. A theorem of Thue asserts that, using only three symbols, one can produce arbitrarily long nonrepetitive sequences. In this paper we consider a natural generalization of Thue's sequences for colorings of graphs. A coloring of the set of edges of a given graph G is nonrepetitive if the sequence of colors on any path in G is nonrepetitive. We call the minimal number of colors needed for such a coloring the Thue number of G and denote it by π(G). The main problem we consider is the relation between the numbers π(G) and Δ(G). We show, by an application of the Lovász Local Lemma, that the Thue number stays bounded for graphs with bounded maximum degree, in particular, π(G) ≤ cΔ(G)2 for some absolute constant c. For certain special classes of graphs we obtain linear upper bounds on π(G), by giving explicit colorings. For instance, the Thue number of the complete graph Kn is at most 2n − 3, and π(T) ≤ 4(Δ(T) − 1)for any tree T with at least two edges. We conclude by discussing some generalizations and proposing several problems and conjectures. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 336–346, 2002
On characterizing hypergraph regularity
Authors: Dementieva Y. , Haxell P. E. , Nagle B. , Rödl V.
Published: October 2002

Szemerédi's Regularity Lemma is a well‐known and powerful tool in modern graph theory. This result led to a number of interesting applications, particularly in extremal graph theory. A regularity lemma for 3‐uniform hypergraphs developed by Frankl and Rödl [8] allows some of the Szemerédi Regularity Lemma graph applications to be extended to hypergraphs. An important development regarding Szemerédi's Lemma showed the equivalence between the property of ϵ‐regularity of a bipartite graphGand an easily verifiable property concerning the neighborhoods of its vertices (Alon et al. [1]; cf. [6]). This characterization of ϵ‐regularity led to an algorithmic version of Szemerédi's lemma [1]. Similar problems were also considered for hypergraphs. In [2], [9], [13], and [18], various descriptions of quasi‐randomness ofk‐uniform hypergraphs were given. As in [1], the goal of this paper is to find easily verifiable conditions for the hypergraph regularity provided by [8]. The hypergraph regularity of [8] renders quasi‐random “blocks of hyperedges” which are very sparse. This situation leads to technical difficulties in its application. Moreover, as we show in this paper, some easily verifiable conditions analogous to those considered in [2] and [18] fail to be true in the setting of [8]. However, we are able to find some necessary and sufficient conditions for this hypergraph regularity. These conditions enable us to design an algorithmic version of a hypergraph regularity lemma in [8]. This algorithmic version is presented by the authors in [5]. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 293–335, 2002
Gaussian averages, Bernoulli averages, and Gibbs' measures
Authors: Talagrand Michel
Published: October 2002

We prove a new comparison principle between the expected value of the supremum of a family of r.v. of the type ∑i≤N giai, where (gi) are i.i.d. standard gaussian, and the expected value of the supremum of the same family when the r.v. gi are replaced by Bernoulli r.v. ηi, P(ηi = ±1) = 1/2. The main idea is to approximate the supremum by a weighted average, an idea well known in the theory of spin glasses. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 197–204, 2002
The minimum expectation selection problem
Authors: Eppstein David , Lueker George S.
Published: October 2002

We define the min–min expectation selection problem (resp. max–min expectation selection problem) to be that of selecting k out of n given discrete probability distributions, to minimize (resp. maximize) the expectation of the minimum value resulting when independent random variables are drawn from the selected distributions. We assume each distribution has finitely many atoms. Let d be the number of distinct values in the support of the distributions. We show that if d is a constant greater than 2, the min‐min expectation problem is 𝒩𝒫‐complete but admits a fully polynomial time approximation scheme. For d an arbitrary integer, it is 𝒩𝒫‐hard to approximate the min‐min expectation problem within any constant approximation factor. The max‐min expectation problem is polynomially solvable for constant d; we leave open its complexity for variable d. We also show similar results for binary selection problems in which we must choose one distribution from each of n pairs of distributions. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 278–292, 2002
Decycling numbers of random regular graphs
Authors: Bau Sheng , Wormald Nicholas C. , Zhou Sanming
Published: October 2002

The decycling number ϕ(G) of a graph G is the smallest number of vertices which can be removed from G so that the resultant graph contains no cycles. In this paper, we study the decycling numbers of random regular graphs. For a random cubic graph G of order n, we prove that ϕ(G) = ⌈n/4 + 1/2⌉ holds asymptotically almost surely. This is the result of executing a greedy algorithm for decycling G making use of a randomly chosen Hamilton cycle. For a general random d‐regular graph G of order n, where d ≥ 4, we prove that ϕ(G)/n can be bounded below and above asymptotically almost surely by certain constants b(d) and B(d), depending solely on d, which are determined by solving, respectively, an algebraic equation and a system of differential equations. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 397–413, 2002
Visual modelling: from images to images
Authors: Pollefeys Marc , Van Gool Luc
Published: October 2002

This paper contains two parts. In the first part an automatic processing pipeline is presented that analyses an image sequence and automatically extracts camera motion, calibration and scene geometry. The system combines state‐of‐the‐art algorithms developed in computer vision, computer graphics and photogrammetry. The approach consists of two stages. Salient features are extracted and tracked throughout the sequence to compute the camera motion and calibration and the 3D structure of the observed features. Then a dense estimate of the surface geometry of the observed scene is computed using stereo matching. The second part of the paper discusses how this information can be used for visualization. Traditionally, a textured 3D model is constructed from the computed information and used to render new images. Alternatively, it is also possible to avoid the need for an explicit 3D model and to obtain new views directly by combining the appropriate pixels from recorded views. It is interesting to note that even when there is an ambiguity on the reconstructed geometry, correct new images can often still be generated. Copyright © 2002 John Wiley & Sons, Ltd.
Single‐view modelling of free‐form scenes
Authors: Zhang Li , Dugas‐Phocion Guillaume , Samson Jean‐Sebastien , Seitz Steven M.
Published: October 2002

This paper presents a novel approach for reconstructing free‐form, texture‐mapped, 3D scene models from a single painting or photograph. Given a sparse set of user‐specified constraints on the local shape of the scene, a smooth 3D surface that satisfies the constraints is generated. This problem is formulated as a constrained variational optimization problem. In contrast to previous work in single‐view reconstruction, our technique enables high‐quality reconstructions of free‐form curved surfaces with arbitrary reflectance properties. A key feature of the approach is a novel hierarchical transformation technique for accelerating convergence on a non‐uniform, piecewise continuous grid. The technique is interactive and updates the model in real time as constraints are added, allowing fast reconstruction of photorealistic scene models. The approach is shown to yield high‐quality results on a large variety of images. Copyright © 2002 John Wiley & Sons, Ltd.
Biophysical mechanisms of phospholipase A2 activation and their use in liposome‐based drug delivery
Authors: Jørgensen Kent , Davidsen Jesper , Mouritsen Ole G
Published: October 2002

Secretory phospholipase A2 (PLA2) is a ubiquitous water‐soluble enzyme found in venom, pancreatic, and cancerous fluid. It is also known to play a role in membrane remodeling processes as well as in cellular signaling cascades. PLA2 is interfacially active and functions mainly on organized types of substrate, e.g. micelles and lipid bilayers. Hence the activity of the enzyme is modulated by the lateral organization and the physical properties of the substrate, in particular the structure in the nanometer range. The evidence for nano‐scale structure and lipid domains in bilayers is briefly reviewed. Results obtained from a variety of experimental and theoretical studies of PLA2 activity on lipid‐bilayer substrates are then presented which provide insight into the biophysical mechanisms of PLA2 activation on lipid bilayers and liposomes of different composition. The insight into these mechanisms has been used to propose a novel principle for liposomal drug targeting, release, and absorption triggered by secretory PLA2.
The regulation of phospholipase D by inositol phospholipids and small GTPases
Authors: Powner Dale J , Wakelam Michael J.O
Published: October 2002

Phospholipase D1 and D2 (PLD1, PLD2) both have PX and PH domains in their N‐terminal regions with these inositol lipid binding domains playing key roles in regulating PLD activity and localisation. The activity of PLD1 is also regulated by protein kinase C and members of the Rho and Arf families of GTPases. Each of these proteins binds to unique sites; however, there appears to be little in vitro discrimination between individual family members. In agonist‐stimulated cells, however, there is specificity, with, for example in RBL‐2H3 cells, antigen stimulating the activation of PLD1 by association with Arf6, Rac1 and protein kinase Cα. PLD2 appears to be less directly regulated by GTPases and rather is primarily controlled through interaction with phosphatidylinositol 4‐phosphate 5‐kinase that generates the activating phosphatidylinositol 4,5‐bisphosphate.
Expression and function of phospholipase A2 in brain
Authors: Balboa Marı́a A , Varela-Nieto Isabel , Killermann Lucas Karin , Dennis Edward A
Published: October 2002

Phospholipase A2 (PLA2) appears to play a fundamental role in cell injury in the central nervous system. We have investigated PLA2 expression in the astrocytoma cell line 1231N1, and found that GIVA, GIVB, GIVC and GVI PLA2 messages are expressed. PLA2 activity is increased by inflammatory/injury stimuli such as interleukin‐1β and lipopolysaccharide in these cells but with very different time courses. The arachidonic acid liberated is converted to prostaglandin E2, possibly by cyclooxygenase‐2, which is induced by inflammatory stimuli. This cell system emerges as a model to study injury/inflammation‐related activation of the new PLA2 forms GIVB and GIVC.
Monosialyl‐Gb5 organized with cSrc and FAK in GEM of human breast carcinoma MCF‐7 cells defines their invasive properties
Authors: Steelant Wim F , Kawakami Yasushi , Ito Akihiro , Handa Kazuko , Bruyneel Erik A , Mareel Marc , Hakomori Senitiroh
Published: October 2002

Two human mammary carcinoma cell variants, MCF‐7/AZ and MCF‐7/6, show the same composition in their glycosphingolipid‐enriched microdomain (GEM) with regard to globo‐series structures Gb3, Gb4, Gb5, monosialyl‐Gb5, GM2, and cSrc and FAK. Both variants are non‐invasive into collagen gel layer, and showed similar motility in wound migration assay. Whereas invasiveness and motility of MCF‐7/AZ cells were enhanced greatly by treatment with mAb RM1 directed to monosialyl‐Gb5, the same RM1 treatment had no effect on MCF‐7/6. cSrc and FAK of MCF‐7/AZ, but not MCF‐7/6, were activated by RM1 treatment. Thus, malignancy of MCF‐7 is highly dependent on monosialyl‐Gb5, and its activation of cSrc and FAK in GEM.
Role of sphingomyelinase and ceramide in modulating rafts: do biophysical properties determine biologic outcome?
Authors: Cremesti Aida E , Goni Felix M , Kolesnick Richard
Published: October 2002

Recent biophysical data suggest that the properties of ceramide observed in model membranes may apply to biological systems. In particular, the ability of ceramide to form microdomains, which coalesce into larger platforms or macrodomains, appears to be important for some cellular signaling processes. Several laboratories have now demonstrated similar reorganization of plasma membrane sphingolipid rafts, via ceramide generation, into macrodomains. This event appeared necessary for signaling upon activation of a specific set of cell surface receptors. In this article, we review the properties and functions of rafts, and the role of sphingomyelinase and ceramide in the biogenesis and re‐modeling of these rafts. As clustering of some cell surface receptors in these domains may be critical for signal transduction, we propose a new model for transmembrane signal transmission.
Mechanical stretching force promotes collagen synthesis by cultured cells from human ligamentum flavum via transforming growth factor‐β1
Authors: Nakatani Tetsuya , Marui Takashi , Hitora Toshiaki , Doita Minoru , Nishida Kotaro , Kurosaka Masahiro
Published: October 2002

Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligamentum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on collagen synthesis and transforming growth factor‐β1 (TGF‐β1) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamentum flavum cells (LFCs) were isolated from human ligamentum flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a commercially available stretching device that physically deformed the cells. Collagen synthesis and TGF‐β1 production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of collagen types I, III, and V in LFCs subjected to mechanical stretching force. The increase in collagen gene expression of LFCs was inhibited in the presence of anti‐TGF‐β1 antibodies. Production of TGF‐β1 by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF‐β1 was confirmed to increase collagen synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF‐β1 production by LFCs, resulting in hypertrophy of the ligament.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Development of the attachment zones in the rat anterior cruciate ligament: changes in the distributions of proliferating cells and fibrillar collagens during postnatal growth
Authors: Nawata Koji , Minamizaki Takeshi , Yamashita Yasutugu , Teshima Ryota
Published: October 2002

The development of the attachment zones of the anterior cruciate ligament (ACL) is an important consideration when examining the structural properties. The aim of this study was to elucidate the morphological changes and the distribution of proliferating cells and collagen types I, II and III at the attachment zones of the rat ACL during postnatal growth.

The majority of proliferating cell nuclear antigen (PCNA) immunostained cells were noted near the ligament insertion, especially at the tibial site, and these cells gradually changed to fibrochondrocyte‐like cells but still produced collagen types I and III at birth until one month old when rapid longitudinal growth of the ACL took place. After one month when the rate of the ligament growth decreased to one thirtieth of that during the first month and the epiphyseal cartilage at the attachment zone had been replaced by bone, these fibrochondrocyte‐like cells began to produce collagen type II and reveal safranin O staining. The immunolabelling pattern to collagen type III was similar to that of PCNA immunostaining during the growth phase.

Our findings show that the fibrochondrocytes at the attachment zone may develop from the ligament cells and act as a growth zone for the ligament during the period of ligament growth, and that subsequently, these cells begin to synthesis collagen type II and proteoglycans after epiphyseal ossification. These observations mainly occurred at the tibial attachment zone.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Parathyroid hormone‐related peptide and Indian hedgehog expression patterns in naturally acquired equine osteochondrosis
Authors: Semevolos Stacy A. , Brower‐Toland Brent D. , Bent Stephen J. , Nixon Alan J.
Published: October 2002

Early changes in parathyroid hormone‐related peptide (PTH‐rP) and Indian hedgehog (Ihh) expression were examined in equine articular osteochondrosis (OC) as a model of a naturally acquired dyschondroplasia. Cartilage was harvested from OC‐affected femoropatellar or scapulohumeral joints from immature horses and normal control horses of similar age. PTH‐rP expression levels were assessed by semi‐quantitative PCR, in situ hybridization, and immunohistochemistry. Ihh protein expression levels were assessed by immunohistochemistry. Elevated PTH‐rP protein and mRNA expression were identified in the deeper layers of affected articular cartilage and the fibrous tissue of interposing clefts. These changes were confined to the chondrocytes in the OC‐affected cartilage, which had significantly increased PTH‐rP protein and mRNA expression when compared to control cartilages. Ihh protein expression showed similar distribution as PTH‐rP in the deeper layers of articular cartilage; however, only a trend for increased Ihh immunostaining was evident in the OC cartilage when compared to the normal cartilage. Increased PTH‐rP expression in pre‐hypertrophic chondrocytes of diseased OC cartilage suggests a possible link between this peptide and the delayed ossification, which is a consistent histologic alteration in OC. More evidence is necessary to determine the role of Ihh in articular cartilage and if a similar feedback cycle exists as previously described for the growth plate.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Cryopreservation of intact human articular cartilage
Authors: Jomha N. M. , Lavoie G. , Muldrew K. , Schachar N. S. , McGann L. E.
Published: October 2002

Damaged articular cartilage (AC) impairs joint function and many treatment techniques are being investigated to determine their long term results. Successful cryopreservation of AC can provide a reliable source of intact matrix with viable chondrocytes to maintain the cartilage over long periods of time. This study investigated the application of an established cryopreservation protocol to determine the recovery of intact chondrocytes from human AC. Ten millimeter diameter osteochondral dowels were harvested from two human donors. The cryopreservation protocol was performed and the samples were rapidly warmed from varying experimental holding temperatures (−10, −20, −30, −40°C), with and without plunging into liquid nitrogen, using 1 M dimethyl sulfoxide as cryoprotectant. The cartilage was stained with membrane integrity dyes and viewed under fluorescence microscopy. The percent of intact chondrocytes was compared to fresh controls. Low recovery of intact chondrocytes was recorded from all temperature levels with and without cryoprotectant. The results of this experiment demonstrated that the cryopreservation procedure used to achieve moderate success with intact sheep AC was not successful with intact human AC and further investigation is required.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effects of combined administration of transforming growth factor‐β1 and epidermal growth factor on properties of the in situ frozen anterior cruciate ligament in rabbits
Authors: Sakai Toshihiko , Yasuda Kazunori , Tohyama Harukazu , Azuma Hirotaka , Nagumo Akira , Majima Tokifumi , Frank Cyril B.
Published: October 2002

The mechanical properties of tendon autografts used in reconstruction of the anterior cruciate ligament (ACL) are reduced after surgery. Previous studies showed that growth factors such as transforming growth factor‐β1 (TGF‐β1) and epidermal growth factor (EGF) can stimulate fibroblast proliferation and increase collagen and noncollagenous protein synthesis by these cells. These factors might be useful, therefore, in preventing graft deterioration after transplantation or accelerating mechanical restoration of the deteriorated graft. The purpose of our study, therefore, was to clarify the effects of TGF‐β1 and EGF on biomechanical properties using an in situ freeze‐thaw ACL model in the rabbit. A total of 142 rabbits underwent the freeze‐thaw treatment in the right ACL and were then divided into four groups. Group I served as a freeze‐thaw, but otherwise untreated control. In Group II, a delivery vehicle (fibrin sealant) alone was applied. In Group III, 4‐ng TGF‐β1 and 100‐ng EGF mixed with the vehicle were applied. In Group IV, higher doses (2‐μg TGF‐β1 and 50‐μg EGF) of growth factors were mixed with the vehicle. The groups were compared at 6 and 12 weeks on the basis of mechanical properties, water content, and histological and ultrastructural observations. The cross‐sectional area of Group III (average, 7.1 mm2) was significantly less than that of Groups I, II, and IV (9.0, 8.2, and 9.4 mm2, respectively) at 12 weeks. The tensile strength of Group III (62.2 MPa) was significantly greater than that of Groups I, II, and IV (35.6, 43.7, and 36.9 MPa, respectively) at 12 weeks, while the water content of Group III (70.7%) was significantly lower than that of Group I (75.2%). No other significant differences occurred among Groups I, II, and IV. A unimodal distribution of collagen fibril diameters was noted in Groups I and II, while a bimodal pattern was found in Group III. This study demonstrated that low‐dose application of TGF‐β1 and EGF significantly inhibited not only the increased water content and cross‐sectional area, but also the decreased tensile strength caused by the freeze‐thaw treatment, while a high dose of TGF‐β1 and EGF does not have the same beneficial effects.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Prostaglandin E1 analog inhibits the microglia function: suppression of lipopolysaccharide‐induced nitric oxide and TNF‐α release
Authors: Chuai Miao , Ogata Tadanori , Morino Tadao , Okumura Hideo , Yamamoto Haruyasu , Schubert Peter
Published: October 2002

Release of nitric oxide and TNF‐α, a toxic cytokine, have been reported to accelerate neuronal damage under several pathological conditions, such as trauma or ischemia in the central nervous system. In the present study, we tested the effect of alprostadil alfadex, a prostaglandin El analog, on cultured microglia from the rat spinal cord. The cultured microglia were exposed to lipopolysaccharide (LPS) (100 ng/ml), an endotoxin, for 24 h, then the released nitric oxide and TNF‐α in the culture media was analyzed. The released nitric oxide was detected by the Griess reaction and released TNF‐α was measured using ELISA method. The LPS‐induced nitric oxide release was inhibited by the simultaneous addition of alprostadil alfadex in a dose‐dependent manner (0.1–100 μM). The LPS‐induced TNF‐α release was also inhibited by alprostadil alfadex addition (0.1–100 μM). The IC50 values of alprostadil alfadex on nitric oxide and TNF‐α release were about 1 and 10 μM, respectively. These results suggest that prostaglandin El possibly protects spinal cord neurons from several types of neurodegenerative damage, not only via increased blood supply, but also via inhibition of pathological immunoreactions of activated microglia.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Defective neurite outgrowth in aphidicolin/cAMP‐induced motor neurons expressing mutant Cu/Zn superoxide dismutase
Authors: Lee Kwang‐Woo , Kim Hyun‐Jeong , Sung Jung‐Joon , Park Kyung‐Seok , Kim Manho
Published: October 2002

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motor neuron involvement. Mutations in the human Cu/Zn superoxide dismutase (SOD1) gene are found in some cases of familial ALS. Many studies have reported SOD1 mutation‐related neurodegeneration. However, whether or not a mutant SOD1 affects neural development has not been demonstrated. We developed motor neuron‐neuroblastoma hybrid cells that expressed a mutant (G93A) or the wild type (WT) SOD1. Cells were differentiated by dibutyryl cAMP and aphidicolin. The mutant showed a defect in neurite outgrowth and had decreased viability. Cytochrome c released and nuclear fragmentation were observed. Western blot analysis showed that the amount of neurofilament and microtubule associated proteins‐2 (MAP‐2) decreased during differentiation. These results suggest that the defect in neurite outgrowth of mutant SOD1 cells is a cytoskeletal defect and is associated with neuronal death.
Ontogenetic development and neuroanatomical localization of growth hormone‐releasing hormone (GHRH) in the brain and pituitary gland of pejerrey fish Odontesthes bonariensis
Authors: Miranda Leandro Andrés , Strobl‐Mazzulla Pablo Hernán , Somoza Gustavo Manuel
Published: October 2002

The presence and distribution of growth hormone‐releasing hormone (GHRH) were studied by immunocytochemistry in adult and developing pejerrey fish, Odontesthes bonariensis (Atheriniformes). A few perikarya and fibers with immunoreactivity to GHRH (ir‐GHRH) were identified in the olfactory bulbs at hatching. One week later, scattered ir‐GHRH cell bodies were observed in the preoptic area and some fibers were detected entering the pituitary gland. Isolated ir‐GHRH perikarya were revealed in the hypothalamus and in the medulla oblongata (MO) 3 weeks after hatching. Seven weeks after hatching, ir‐GHRH cells were also identified in the nucleus of the lateral lemniscus and the cerebellum. Both nuclei presented strong ir‐GHRH projections extending rostro‐ventrally. At 11 weeks after hatching another group of ir‐GHRH cells were revealed in the midbrain tegmentum. After that time the pattern of distribution of ir‐GHRH structures remained unchanged. At 1 week after hatching and later, the pituitary gland consistently revealed ir‐GHRH cells and fibers mainly in the proximalis pars distalis and in a minor proportion of the pars intermedia since week 1. The pineal gland showed ir‐GHRH cells projecting into the pineal lumen, at week 6 after hatching and later. The pineal stalk and the subcomissural organ also presented ir‐GHRH structures. Additionally, ir‐GHRH material was found from week 3 to the adult stage in the following extraneural organs: gills, gut, kidney and hepatopancreas. These results represent the anatomical substrate for understanding the physiology of GHRH peptide in pejerrey, adding information on the ontogeny of neural structures expressing GHRH.
METASTABILITY IN THE CLASSICAL, TRUNCATED BECKER–DÖRING EQUATIONS
Authors: Duncan Dugald B. , Dunwell Rachel M.
Published: October 2002

We show that in the classical (fixed-monomer-concentration) Becker–Döring equations truncated at finite cluster size, the slow evolution (metastability) of solutions can be explained in terms of the eigensystem of this linear ordinary differential equation (ODE) system. In particular, for a common choice of coagulation–fragmentation rate constants there is an extremely small non-zero eigenvalue which is isolated from the rest of the spectrum. We give estimates and bounds on the size of this eigenvalue, the gap between it and the second smallest, and the size of the largest eigenvalue. The bounds on the smallest eigenvalue are very sharp when the system size and/or monomer concentration are large enough.

AMS 2000 Mathematics subject classification: Primary 34A30; 15A18; 65F15
MAXIMAL IDEALS IN THE ALGEBRA OF OPERATORS ON CERTAIN BANACH SPACES
Authors: Laustsen Niels Jakob
Published: October 2002

For a Banach space $\mathfrak{X}$, let $\mathcal{B}(\mathfrak{X})$ denote the Banach algebra of all continuous linear operators on $\mathfrak{X}$. First, we study the lattice of closed ideals in $\mathcal{B}(\mathfrak{J}_p)$, where $1 \lt p \t \infty$ and $\mathfrak{J}_p$ is the $p$th James space. Our main result is that the ideal of weakly compact operators is the unique maximal ideal in $\mathcal{B}(\mathfrak{J}_p)$. Applications of this result include the following.

(i) The Brown–McCoy radical of $\mathcal{B}(\mathfrak{X})$, which by definition is the intersection of all maximal ideals in $\mathcal{B}(\mathfrak{X})$, cannot be turned into an operator ideal. This implies that there is no ‘Brown–McCoy’ analogue of Pietsch’s construction of the operator ideal of inessential operators from the Jacobson radical of $\mathcal{B}(\mathfrak{X})/\mathcal{A}(\mathfrak{X})$.

(ii) For each natural number $n$ and each $n$-tuple $(m_1,\dots,m_n)$ in $\{k^2\mid k\in\mathbb{N}\}\cup\{\infty\}$, there is a Banach space $\mathfrak{X}$ such that $\mathcal{B}(\mathfrak{X})$ has exactly $n$ maximal ideals, and these maximal ideals have codimensions $m_1,\dots,m_n$ in $\mathcal{B}(\mathfrak{X})$, respectively; the Banach space $\mathfrak{X}$ is a finite direct sum of James spaces and $\ell_p$-spaces.

Second, building on the work of Gowers and Maurey, we obtain further examples of Banach spaces $\mathfrak{X}$ such that all the maximal ideals in $\mathcal{B}(\mathfrak{X})$ can be classified. We show that the ideal of strictly singular operators is the unique maximal ideal in $\mathcal{B}(\mathfrak{X})$ for each hereditarily indecomposable Banach space $\mathfrak{X}$, and we prove that there are $2^{2^{\aleph_0}}$ distinct maximal ideals in $\mathcal{B}(\mathfrak{G})$, where $\mathfrak{G}$ is the Banach space constructed by Gowers to solve Banach’s hyperplane problem.

AMS 2000 Mathematics subject classification: Primary 47D30; 47D50; 46H10; 16D30
A DIMENSION-DEPENDENT MAXIMAL INEQUALITY
Authors: Shvidkoy Roman
Published: October 2002

In this short note we show that $\sup\{\|M_\nu\|:\nu\text{ is a measure on }\mathbb{R}^n\}$, where $\|M_\nu\|$ denotes the centred Hardy–Littlewood maximal operator, depends exponentially on $n$.

AMS 2000 Mathematics subject classification: Primary 42B25
ON THE FREIHEITSSATZ IN CERTAIN ONE-RELATOR FREE PRODUCTS. III
Authors: Shwartz Robert
Published: October 2002

We study one-relator free products in which the relator has free-product length $4$. We find conditions for such presentations to have a Freiheitssatz and classify all non-aspherical presentations under certain conditions.

AMS 2000 Mathematics subject classification: Primary 20F05; 20F06; 20F10
BANACH ALGEBRAS WEAK* GENERATED BY THEIR IDEMPOTENTS
Authors: Pedersen Thomas Vils
Published: October 2002

For a closed set $E$ contained in the closed unit interval, we show that the big Lipschitz algebra $\varLambda_{\gamma}(E)$ $(0\lt\gamma\lt1)$ is sequentially weak$^{\ast}$ generated by its idempotents if and only if it is weak$^{\ast}$ generated by its idempotents if and only if the little Lipschitz algebra $\lambda_{\gamma}(E)$ is generated by its idempotents, and we describe a class of perfect symmetric sets for which this holds. Moreover, we prove that $\varLambda_1(E)$ is sequentially weak$^{\ast}$ generated by its idempotents if and only if $E$ is of measure zero. Finally, we show that the quotient algebras

$$ \mathcal{A}_{\beta}/\overline{J_{\beta}(E)}^{\text{weak}^{\ast}} $$

of the Beurling algebras need not be weak$^{\ast}$ generated by their idempotents, when $E$ is of measure zero and $\beta\ge\tfrac{1}{2}$.

AMS 2000 Mathematics subject classification: Primary 46J10; 46J30; 26A16; 42A16
The influence of weather on annual yields of honey
Authors: HOLMES W.
Published: October 2002

The influence of weather conditions on the average yield of honey in one apiary over a period of 30 years in the UK has been studied. In highly significant multiple regression equations weather variables accounted for over 80% of the variation in annual average honey yield. Weather in March, May and June had the major effects. Implications and applications of the equations are considered.
Effects of spray application of urea fertilizer at stem extension on winter wheat yield
Authors: READMAN R. J. , KETTLEWELL P. S. , BECKWITH C. P.
Published: October 2002

Supplying a proportion of the N requirement of a wheat crop via the foliage would potentially reduce immobilization of fertilizer N in the soil organic matter and N losses by leaching or denitrification. A field experiment was carried out at Harper Adams in Shropshire to investigate the effect on crop yield of supplying the spring N application to winter wheat as different proportions of urea as a solution rather than as conventional soil-applied urea, and to determine the physiological basis of any yield differences. A solid ammonium nitrate treatment was included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. Solid fertilizer was applied as a single dressing, whereas urea sprays were split over a number of days to reduce scorch. Nitrogen as urea sprays produced similar grain yields to N applied conventionally to the soil as solid ammonium nitrate or urea, but effects on above-ground dry matter production and harvest index depended on the time of application. Application of a large proportion of N as urea sprays, such that some of the N as urea solution was applied later in relation to crop development, produced less above-ground dry matter, but compensated by increasing harvest index. It is concluded that application of N as urea sprays could be successfully used to substitute for soil-applied N fertilizer at stem extension in winter wheat without loss of yield. Extra application costs, however, are likely to outweigh any efficiency or environmental benefits, except where applications of solid N are made to dry soils.
Viscous fingering in non-Newtonian fluids
Authors: LINDNER ANKE , BONN DANIEL , POIRÉ EUGENIA CORVERA , AMAR MARTINE BEN , MEUNIER JACQUES
Published: October 2002

We study the viscous fingering or Saffman–Taylor instability in two different dilute or
semi-dilute polymer solutions. The different solutions exhibit only one non-Newtonian
property, in the sense that other non-Newtonian effects can be neglected. The viscosity of solutions of stiff polymers has a strong shear rate dependence. Relative to
Newtonian fluids, narrower fingers are found for rigid polymers. For solutions of
flexible polymers, elastic effects such as normal stresses are dominant, whereas the
shear viscosity is almost constant. Wider fingers are found in this case. We characterize the non-Newtonian flow properties of these polymer solutions completely,
allowing for separate and quantitative investigation of the influence of the two most
common non-Newtonian properties on the Saffman–Taylor instability. The effects of
the non-Newtonian flow properties on the instability can in all cases be understood
quantitatively by redefining the control parameter of the instability.
Turbulent diffusion in the geostrophic
inverse cascade
Authors: SMITH K. S. , BOCCALETTI G. , HENNING C. C. , MARINOV I. , TAM C. Y. , HELD I. M. , VALLIS G. K.
Published: October 2002

Motivated in part by the problem of large-scale lateral turbulent heat transport in the
Earth's atmosphere and oceans, and in part by the problem of turbulent transport
itself, we seek to better understand the transport of a passive tracer advected by
various types of fully developed two-dimensional turbulence. The types of turbulence
considered correspond to various relationships between the streamfunction and the
advected field. Each type of turbulence considered possesses two quadratic invariants
and each can develop an inverse cascade. These cascades can be modified or halted, for
example, by friction, a background vorticity gradient or a mean temperature gradient.
We focus on three physically realizable cases: classical two-dimensional turbulence,
surface quasi-geostrophic turbulence, and shallow-water quasi-geostrophic turbulence
at scales large compared to the radius of deformation. In each model we assume that
tracer variance is maintained by a large-scale mean tracer gradient while turbulent
energy is produced at small scales via random forcing, and dissipated by linear
drag. We predict the spectral shapes, eddy scales and equilibrated energies resulting
from the inverse cascades, and use the expected velocity and length scales to predict
integrated tracer fluxes.

When linear drag halts the cascade, the resulting diffusivities are decreasing functions of the drag coefficient, but with different dependences for each case. When β is
significant, we find a clear distinction between the tracer mixing scale, which depends
on β but is nearly independent of drag, and the energy-containing (or jet) scale, set
by a combination of the drag coefficient and β. Our predictions are tested via high-
resolution spectral simulations. We find in all cases that the passive scalar is diffused
down-gradient with a diffusion coefficient that is well-predicted from estimates of
mixing length and velocity scale obtained from turbulence phenomenology.
The reflection of asymmetric shock waves in
steady flows: a numerical investigation
Authors: IVANOV M. S. , BEN-DOR G. , ELPERIN T. , KUDRYAVTSEV A. N. , KHOTYANOVSKY D. V.
Published: October 2002

The theoretical study and experimental investigation of the reflection of asymmetric
shock waves in steady flows reported by Li et al. (1999) are complemented by a
numerical simulation. All the findings reported in both the theoretical study and the
experimental investigation were also evident in the numerical simulation. In addition
to weak regular reflection and Mach reflection wave configurations, strong regular
reflection and inverse-Mach reflection wave configurations were recorded numerically.
The hysteresis phenomenon, which was hypothesized in the course of the theoretical
study and then verified in the experimental investigation, was also observed in the
numerical simulation.
Exact solutions for rotating vortex arrays with
finite-area cores
Authors: CROWDY DARREN G.
Published: October 2002

A class of explicit solutions of the two-dimensional Euler equations consisting of
a finite-area patch of uniform vorticity surrounded by a finite distribution of co-
rotating satellite line vortices is constructed. The results generalize the classic study
of co-rotating vortex arrays by J. J. Thomson. For N satellite line vortices (N [ges ] 3)
a continuous one-parameter family of rotating vortical equilibria is derived in which
different values of the continuous parameter correspond to different shapes and areas
of the central patch. In an appropriate limit, vortex patch equilibria with cusped
boundaries are found. A study of the linear stability is performed and a wide range
of the solutions found to be linearly stable. Contour dynamics methods are used to
calculate the typical nonlinear evolution of the configurations. The results are believed
to provide the only known exact solutions involving rotating vortex patches besides
the classical Kirchhoff ellipse.
Are habitat generalists affected by forest fragmentation? A test with Eurasian badgers (Meles meles) in coarse‐grained fragmented landscapes of central Spain
Authors: Virgós Emilio
Published: October 2002

This study assesses the pattern of occurrence of a generalist species, the Eurasian badger Meles meles, in forest fragments located in agricultural landscapes of central Spain with a coarse‐grained pattern of fragmentation (<20% forest cover in the landscape). Four forest regions (n= 139 forest fragments) were sampled. Badger presence/absence in forest fragments was studied in relation to: forest size, isolation and vegetation structure. Badgers were tested to see if, despite their habitat generalism, they were negatively affected by forest fragmentation in this type of fragmented landscape. Results indicated a strong and significant effect of fragment size on badger occurrence (presence was rare in forest fragments <100 ha) and an important effect of isolation at a local scale. The response of badgers to forest fragmentation in Spain is quite different to the response in other European landscapes. In Spain, badgers cope with a divided coarse‐grained landscape where suitable habitats are embedded in a largely unsuitable matrix (cereal croplands). In contrast, in Britain or central Europe, badgers may be benefited by forest clearances in a heterogeneous but non‐divided landscape where small woodlots are separated by a matrix of good quality (mainly pastures) and fragmentation produces fine‐grained mosaic landscapes where food and den sites are simultaneously enhanced. Species' response to forest fragmentation may strongly depend on the pattern of fragmentation and, in coarse‐grained fragmented landscapes, generalist species may be affected in the same way as specialist ones.