bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of parabolic dunes from barchan and transverse dunes along Israel's Mediterranean coast
Authors: Tsoar Haim , Blumberg DAN G. 
Published: October 2002

AbstractThe Mediterranean coastal dunes of Israel underwent a land‐use change during the second half of the 20th century. Due to intense agricultural and pastoral activity, the coastal dunes were stripped of natural vegetation until the end of the first half of the 20th century. The barchan and transverse dunes were shaped by strong southwesterly winter winds. A decrease in human activity during the second half of the 20th century brought about a renewal of natural vegetation on the dune crest—the only area with neither erosion nor deposition. The establishment of vegetation on the crest changes the dynamics of these barchan and transverse dunes, so that not all of the sand eroded from the windward side is carried to the lee slip‐face; some is trapped by plants. Consequently, there is a change in the shape of the windward slope from convex to concave, and the dune gradually becomes parabolic. In this study we trace the morphodynamics of the dunes by analysing 12 sets of aerial photographs, which were taken from 1944 to 1995. The average rate of advance of 15 dunes has decreased from 3·4 m a−1to 1·9 m a−1, while the vegetation cover has increased from 4·3 to 17 per cent during this period. Copyright © 2002 John Wiley & Sons, Ltd.
Long‐term landform evolution: evidence from talus studies
Authors: van Steijn Henk 
Published: October 2002

AbstractCurrent concepts of long‐term landform change like equilibrium, characteristic forms or the role of climate were developed with the denudational history of landscapes in mind. In this paper some long‐term aspects of talus development are discussed as an example of the potential contribution from dominantly depositional environments to the more theoretical concepts of geomorphology. Evolutions during periods of 102 to 103 years as well as during longer periods (in the order of 104 to 105 years) are mentioned. Interpretations of geomorphological evolution for the latter time scale and within a regional context may be obtained from the information contained within the shorter time slices studied in detail on individual taluses. Periods for which the evolution of part of a talus is known in detail, in terms of process types and sequences in relation to climate and other environmental factors, are indicated here as time slices. It is suggested that the combination of such time slices for a given region may result in a more or less complete picture of geomorphological and environmental evolution for relatively long periods. The image obtained is additional to information from other reconstructions of environmental conditions. Two examples of talus research are discussed to explain the intentions of the paper.Concluding statements draw attention to the potentially strong relationships between properties of talus deposits and environmental conditions. This is especially important for information that cannot be obtained from other sources like pollen analysis, for instance about precipitation characteristics. At a more general level of geomorphology, a possible modification of ideas is proposed about the influence of climate on the functioning of certain geomorphological systems. Further consequences of the results are the need to re‐think concepts like equilibrium or characteristic form. Copyright © 2002 John Wiley & Sons, Ltd.
A review of two strongly contrasting geomorphological systems within the context of scale
Authors: Cammeraat L. H. 
Published: October 2002

AbstractScale issues are often addressed in contemporary geo‐ecological studies and form one of the major challenges in the fields of physical geography, hydrology and ecology. In this paper the application of hierarchy theory and response units is proposed as an approach towards scale‐transcending environmental studies on degradation and geomorphological development.Goals of the research were to establish which processes are important at what spatio‐temporal scale, how hydro‐geomorphological response is influenced by biological processes and whether hierarchy theory and the response unit approach can be used as an up‐scaling methodology.Results from two climatologically and geomorphological different regions are discussed, one dominated by water shortage (SE Spain) and the other by water surplus (Luxembourg). In both cases detailed process research was carried out at scales ranging from the micro‐plot to the catchment. Process research was concentrated on understanding and quantifying sediment and water transfer through the geo‐ecosystems studied.Outcomes showed that in both cases the role of biological processes was important in the hydrological and degradation response of both areas. This was not only true for the finest scale levels but also had its impact on the emerging properties and response at the hillslope and catchment level.Connectivity of runoff‐generating and runoff‐absorbing areas was important on all scale levels. Connectivity is dominated by both the rainfall magnitude–frequency–duration characteristics and physically and biologically controlled thresholds, which range from initial soil moisture contents, vegetation patterns or soil biological activity, to the presence of water harvesting structures.The complex interrelationships of the processes involved showed that linear up‐scaling from fine to broad scale is impossible, as many thresholds and non‐linear processes are involved at specific scales. The identified response units are used to integrate these complex relationships in a relatively manageable way, and may provide a useful framework for up‐scaling, and for understanding catchment hydro‐geomorphological response and development. Copyright © 2002 John Wiley & Sons, Ltd.
Distributional properties of EMS and non‐EMS exchange rates before and after German reunification
Authors: Laopodis Nikiforos T. 
Published: October 2002

AbstractThe paper explores the stochastic behaviour of four EMS (Belgian franc, French franc, Spanish peseta and Italian lira) and non‐EMS (Canadian dollar, US dollar, Japanese yen and British pound) deutschemark exchange rates, using a GARCH‐type model along with the generalized error distribution, before and after Germany's unification in 1990. The results indicate that there was a fundamental change in the distributions of all exchange rates after Germany's reunification and so the single normal distribution assumption is not appropriate. Although the presence of GARCH remained, all rates' conditional distributions resembled the uniform, in the first period, but they approximated the double exponential in the second. Further, during and after the pound's brief and the lira's longer associations with the ERM their distributions were unchanged. Finally, two other notable results were the reduction in the degree of volatility persistence in all Deutschemark rates during the after‐unification period, and the rates' strong mean‐reverting tendencies. Copyright © 2002 John Wiley & Sons, Ltd.
An infinite series of regular edge‐ but not vertex‐transitive graphs
Authors: Lazebnik Felix , Viglione Raymond 
Published: October 2002

AbstractLet n be an integer and q be a prime power. Then for any 3 ≤ n ≤ q−1, or n=2 and q odd, we construct a connected q‐regular edge‐but not vertex‐transitive graph of order 2qn+1. This graph is defined via a system of equations over the finite field of q elements. For n=2 and q=3, our graph is isomorphic to the Gray graph. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 249–258, 2002
6‐regular 4‐critical graph
Authors: Pyatkin A. V. 
Published: October 2002

AbstractP. Erdős conjectured in [2] that r‐regular 4‐critical graphs exist for every r ≥ 3 and noted that no such graphs are known for r ≥ 6. This article contains the first example of a 6‐regular 4‐critical graph. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 286–291, 2002
Recursive generation of partitionable graphs
Authors: Boros E. , Gurvich V. , Hougardy S. 
Published: October 2002

AbstractResults of Lovász (1972) and Padberg (1974) imply that partitionable graphs contain all the potential counterexamples to Berge's famous Strong Perfect Graph Conjecture. A recursive method of generating partitionable graphs was suggested by Chvátal, Graham, Perold, and Whitesides (1979). Results of Sebő (1996) entail that Berge's conjecture holds for all the partitionable graphs obtained by this method. Here we suggest a more general recursion. Computer experiments show that it generates all the partitionable graphs with ω=3,α ≤ 9 (and we conjecture that the same will hold for bigger α, too) and many but not all for (ω,α)=(4,4) and (4,5). Here, α and ω are respectively the clique and stability numbers of a partitionable graph, that is the numbers of vertices in its maximum cliques and stable sets. All the partitionable graphs generated by our method contain a critical ω‐clique, that is an ω‐clique which intersects only 2ω−2 other ω‐cliques. This property might imply that in our class there are no counterexamples to Berge's conjecture (cf. Sebő (1996)), however this question is still open. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 259–285, 2002
Proof of a conjecture on irredundance perfect graphs
Authors: Volkmann Lutz , Zverovich Vadim E. 
Published: October 2002

AbstractLet ir(G) and γ(G) be the irredundance number and the domination number of a graph G, respectively. A graph G is called irredundance perfect if ir(H)=γ(H), for every induced subgraph H of G. In this article we present a result which immediately implies three known conjectures on irredundance perfect graphs. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 292–306, 2002
Edge‐partitions of planar graphs and their game coloring numbers
Authors: He Wenjie , Hou Xiaoling , Lih Ko‐Wei , Shao Jiating , Wang Weifan , Zhu Xuding 
Published: October 2002

AbstractLet G be a planar graph and let g(G) and Δ(G) be its girth and maximum degree, respectively. We show that G has an edge‐partition into a forest and a subgraph H so that (i) Δ(H) ≤ 4 if g(G) ≥ 5; (ii) Δ(H) ≤ 2 if g(G) ≥ 7; (iii) Δ(H)≤ 1 if g(G) ≥ 11; (iv) Δ(H) ≤ 7 if G does not contain 4‐cycles (though it may contain 3‐cycles). These results are applied to find the following upper bounds for the game coloring number colg(G) of a planar graph G: (i) colg(G) ≤ 8 if g(G) ≥ 5; (ii) colg(G)≤ 6 if g(G) ≥ 7; (iii) colg(G) ≤ 5 if g(G) ≥ 11; (iv) colg(G) ≤ 11 if G does not contain 4‐cycles (though it may contain 3‐cycles). © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 307–317, 2002
Two graphs without planar covers
Authors: Archdeacon Dan 
Published: October 2002

AbstractIn this note we prove that two specific graphs do not have finite planar covers. The graphs are K7–C4 and K4,5–4K2. This research is related to Negami's 1‐2‐∞ Conjecture which states “A graph G has a finite planar cover if and only if it embeds in the projective plane.” In particular, Negami's Conjecture reduces to showing that 103 specific graphs do not have finite planar covers. Previous (and subsequent) work has reduced these 103 to a few specific graphs. This paper covers 2 of the remaining cases. The sole case currently remaining is to show that K2,2,2,1 has no finite planar cover. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 318–326, 2002
Effect of light and oxygen transmission characteristics of packaging materials on photo‐oxidative quality changes in semi‐hard Havarti cheeses
Authors: Mortensen Grith , Sørensen John , Stapelfeldt Henrik 
Published: October 2002

AbstractChanging transmission characteristics of food packaging materials by colouring the materials may be a suitable way of reducing photo‐oxidative quality changes. This study proved that packaging in black laminates provided the best protection of Havarti cheese, followed by a white laminate. However, transparent packaging materials did not protect the product in the critical wavelength range, i.e. 400–500 nm, and changes in colour and odour were already notable after few hours of exposure to fluorescent light. Additionally, secondary oxidation products, hexanal, 1‐pentanol, and 1‐hexanol, were formed in cheese packaged in transparent or semi‐transparent packaging materials. The expected effects of oxygen transmission were difficult to evaluate, due to high residual oxygen levels in the packages. Copyright © 2002 John Wiley & Sons, Ltd.
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

AbstractThe 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

AbstractThe 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

AbstractGravure‐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

AbstractThe 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

AbstractLetHbe 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

AbstractA 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

AbstractSzemerédi'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

AbstractWe 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

AbstractWe 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

AbstractThe 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