bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-dimensional plumes in stratified
environments
Authors: BAINES PETER G.
Published: November 2002

Laboratory experiments on the flow of negatively buoyant two-dimensional plumes
adjacent to a wall in a density-stratified environment are described. The flow passes
through several stages, from an inertial jet to a buoyant plume, to a neutrally
buoyant jet, and then a negatively buoyant plume when it overshoots its equilibrium
density. This fluid then ‘springs back’ and eventually occupies an intermediate range
of heights. The flow is primarily characterized by the initial value of the buoyancy
number, B0 = Q0N3/g′02, where Q0 is the initial volume flux per unit width, g′0 is the
initial buoyancy and N is the buoyancy frequency of the environment. Scaled with the
initial equilibrium depth D of the in flowing fluid, the maximum depth of penetration
increases with B0, as does the width of the initial down flow, which is observed to
increase very slowly with distance downward. Observations are made of the profiles of
flow into and away from the plume as a function of height. Various properties of the
flow are compared with predictions from the ‘standard’ two-dimensional entraining
plume model, and this shows generally consistent agreement, although there are
differences in magnitudes and in details. This flow constrasts with flows down gentle
slopes into stratified environments, where two-way exchange of fluid occurs.
Ekman effects in a rotating flow over bottom
topography
Authors: SANSÓN L. ZAVALA , VAN HEIJST G. J. F.
Published: November 2002

This paper presents a general two-dimensional model for rotating barotropic flows
over topography. The model incorporates in a vorticity–stream function formulation
both inviscid topography effects, associated with stretching and squeezing of fluid
columns enforced by their motion over variable topography, and viscous effects, due
to the Ekman boundary layer at the solid bottom. From the present formulation, conventional two-dimensional models can be recovered. The model is tested by means of
laboratory experiments on homogeneous vortices encountering irregular topographies.
The experimental observations are then compared with the corresponding numerical
simulations based on the general model. The results suggest that such a formulation
incorporates both inviscid and viscous topography effects correctly.
Large-scale dynamics in turbulent mixing
and the three-dimensional space–time
behaviour of outer fluid interfaces
Authors: CATRAKIS HARIS J. , AGUIRRE ROBERTO C. , RUIZ-PLANCARTE JESUS , THAYNE ROBERT D. , McDONALD BRENDA A. , HEARN JOSHUA W.
Published: November 2002

Experiments have been conducted to investigate turbulent mixing and the dynamics
of outer fluid interfaces, i.e. the interfaces between mixed fluid and pure ambient
fluid. A novel six-foot-diameter octagonal-tank flow facility was developed to enable
the optical imaging of fluid interfaces above the mixing transition, corresponding to
fully developed turbulence. Approximately 10003 whole-field three-dimensional space–
time measurements of the concentration field were recorded using laser-induced-
fluorescence digital-imaging techniques in turbulent jets at a Reynolds number of
Re ∼ 20 000, Schmidt number of Sc ∼ 2000, and downstream distance of
∼ 500 nozzle
diameters. Multiple large-scale regions of spatially nearly uniform-concentration fluid
are evident in instantaneous visualizations, in agreement with previous findings above
the mixing transition. The ensemble-averaged probability density function of concentration is found to exhibit linear dependence over a wide range of concentration
thresholds. This can be accounted for in terms of the dynamics of large-scale well-
mixed regions. Visualization of the three-dimensional space–time concentration field
indicates that molecular mixing of entrained pure ambient fluid is dynamically initiated and accomplished in the vicinity of the unsteady large scales. Examination
of the outer interfaces shows that they are dynamically confined primarily near the
instantaneous large-scale boundaries of the flow. This behaviour is quantified in terms
of the probability density of the location of the outer interfaces relative to the flow
centreline and the probability of pure ambient fluid as a function of distance from
the centreline. The current measurements show that the dynamics of outer interfaces
above the mixing transition is significantly different from the behaviour below the
transition, where previous studies have shown that unmixed ambient fluid can extend
across a wide range of transverse locations in the flow interior. The present observations of dynamical confinement of the outer interfaces to the unsteady large scales,
and considerations of entrainment, suggest that the mechanism responsible for this
behaviour must be the coupling of large-scale flow dynamics with the presence of
small-scale structures internal to the large-scale structures, above the mixing transition. The dynamics and structure of the outer interfaces across the entire range of
space–time scales are quantified in terms of a distribution of generalized level-crossing
scales. The outer-interface behaviour determines the mixing efficiency of the flow, i.e.
fraction of mixed fluid. The present findings indicate that the large-scale dynamics of
the outer interfaces above the mixing transition provides the dominant contribution
to the mixing efficiency. This suggests a new way to quantify the mixing efficiency of
turbulent flows at high Reynolds numbers.
Effects of a format-based second language teaching method in kindergarten
Authors: UILENBURG NOËLLE , PLOOIJ FRANS X. , DE GLOPPER KEES , DAMHUIS RESI
Published: November 2002

This article concerns second language teaching with a format-based method. The following
article in this issue concerns foreign language teaching using the same approach. In the present
study, the differences between a format-based teaching approach and a standard approach used as
treatments in a quasi-experimental, nonequivalent control group design are described in detail.
The hypothesis tested is whether the effects of a format-based teaching method and a standard
second language teaching method differ after two years for children at the age of 6. Results of
MANOVA analysis for repeated measures show that the groups are quite comparable on the
dependent variables, with some small differences in development between the two groups.
Univariate results reveal that these differences favor children in the experimental group for sound
articulation and favor children in the control group for sound discrimination. The results of the
present article and those of the following article are discussed in light of broader issues
concerning the differences between second language and foreign language teaching.
The effects of global similarity between stimuli on children's judgment of rime and
alliteration
Authors: CARROLL JULIA M. , SNOWLING MARGARET J.
Published: November 2002

A total of 38 preschool children (3 and 4 years old) were assessed on a set of phonological
awareness tasks three times over the course of a year. The tasks used were rhyme and alliteration
matching tasks with distractor items that were either semantically or phonologically related to the
target. In both tasks, the children found the distractors matched for phonological similarity more
difficult to reject than the semantically related distractors or the unrelated distractors. The results
emphasize the importance of controlling for global phonological factors when designing
phonological awareness tasks. The longitudinal findings are discussed within the context of
current theories on the development of phonological representations.
Sentence comprehension: The integration of habits and rules. David J. Townsend and Thomas G. Bever. Cambridge, MA: MIT Press, 2001. Pp. 455.
Authors: Chipere Ngoni
Published: November 2002

This book attempts to integrate symbolic processing, in the form of minimalism, with connectionism. Minimalism represents sentences as symbolic structures resulting from a formal process of syntactic derivation. Connectionism, on the other hand, represents sentences as patterns of association between linguistic features. These patterns are said to obey statistical regularities of linguistic usage instead of formal linguistic rules. The authors of the book argue that human sentence processing displays both structural and statistical characteristics and therefore requires the integration of the two views.
Language acquisition: The growth of grammar. Maria Teresa Guasti. Cambridge, MA: MIT Press, 2002. Pp. 474.
Authors: Serratrice Ludovica
Published: November 2002

In this introductory textbook to language acquisition Guasti has done an excellent job of presenting the state of the art of generative linguistic research in the field. Her review of the literature is extremely thorough and up to date; and theoretical arguments, empirical findings, and methodological issues are introduced and discussed with great rigor and lucidity.
Dangerous balances, 1816–1989: a simple theory with longitudinal evidence
Authors: Moul William
Published: November 2002

To be explained are the Great Power versus Great Power wars, 1816–1989. Familiar strands of ‘realist’ thinking are twisted into a good simple balances of power theory to explain peace, war and the extent of war. The evidence, quantitative and qualitative, is that non-separated approximate equals in power capabilities formed dangerous balances. Generally, would-be-combatant great powers used alliances to restrain stronger third parties and to add the capabilities of weaker states to their own. The critical importance of political geography, a state's political capacity, and alliance commitments to the balance of power are made plain.
Cooperative hegemony: power, ideas and institutions in regional integration
Authors: Pedersen Thomas
Published: November 2002

For realists regionalism remains a difficult phenomenon to explicate. A particular puzzle for realists is why major states should want to pursue regional institutionalisation. Nor are pluralist accounts satisfactory given the empirical evidence of state actor prominence in processes of regional institutionalisation. This article sets out to account for the formative phase of regionalist endeavours, proposing an ideational–institutional realism as the basis for understanding regionalism. On this basis a specific theory of co-operative hegemony is developed. Stressing the importance of the grand strategies of major regional powers and their responses to the balance-of-threat in a region, the author argues that major states may advance their interests through non-coercive means by applying a strategy of co-operative hegemony which implies an active role in regional institutionalisation and the use of, for instance, side payments, power-sharing and differentiation. The article outlines a number of preconditions for regional institutionalisation, stressing what is called the capacity for power-sharing; the power aggregation capacity and the commitment capacity of the biggest power in a region. While regionalising state elites are constrained, they possess a much greater freedom of choice than neo-realism claims.
E. H. Carr: a ‘historical realist’ approach for the globalisation era
Authors: Goldfischer David
Published: November 2002

Realist international relations scholars have approached the connection between economics and security in two ways. Cold War-era realists derived the national interest from the international balance of power, and assessed the utility of both military and economic instruments of statecraft. A second realist approach, advanced by E. H. Carr in his 1939 The Twenty Years' Crisis, places interstate competition in the context of another struggle over wealth and power in which no-one's primary concern is the national interest. That is the realm of capitalism (and resistance to capitalism). That deeper set of connections between economics and security was overlooked in Cold War IR literature, at considerable cost to our understanding of world politics. Understanding why Carr's ‘historical realism’ was bypassed can help pave the way for a more fruitful realist approach to comprehending a new era in world politics.
History, Christianity and diplomacy: Sir Herbert Butterfield and international relations
Authors: Hall Ian
Published: November 2002

Sir Herbert Butterfield, Master of Peterhouse, Cambridge (1955–68), Regius Professor of History (1963–68), and author of The Whig Interpretation of History (1931), was one of the leading historians of the twentieth century. A diplomatic historian and student of modern historiography, Butterfield was deeply concerned too with contemporary international relations, wrote much on the subject and, in 1958, created the ‘British Committee on the Theory of International Politics’. Drawing upon published and unpublished material, this article seeks to sketch an outline of Butterfield's career and thought, to examine his approach to international relations, and to reconsider his reputation in the field.
Territorial borders, toleration and the English School
Authors: Williams John
Published: November 2002

This article offers an assessment of the ethical status of territorial borders, arguing for a partial defence of their role in international relations. Utilising the English School as one way such a defence has been developed, it assesses pluralist and solidarist arguments, suggesting both are flawed. The article develops a notion of territorial borders as contributing to the value of tolerating difference in international relations, and that this is an ethically desirable thing to do. It doing so it utilises the political theory of Hannah Arendt as an alternative to more common, if usually implicit, liberal understandings.
Sovereign rights in international relations: a futile search for regulated or regular state behaviour
Authors: Kurtulus Ersun N.
Published: November 2002

The article is a critical assessment of three explanations in relation to the question of which types of entities actually enjoy sovereign rights. Concluding that two of these—constitutional independence and legal criteria of statehood—are empirically untenable, it then focuses on a third, more plausible, answer: recognition as a state. Pointing out the almost consensual attitude toward the issue adopted by political scientists and finding the two doctrines of recognition formulated by international lawyers to be imbued with logical inconsistencies, the article concludes by remarking on the impossibility of discovering any clear pattern of state behaviour in this respect.
A response to Kurtulus
Authors: James Alan
Published: November 2002

In the initial section of his article, Ersun Kurtulus criticises the approach to
sovereignty which I advanced in my Sovereign Statehood (1986). There I argued that
the characteristic which distinguishes a sovereign from a non-sovereign state is
constitutional independence—that is to say, a territorial entity's possession of a
constitution which is not subordinate to that of another territorial entity. The most
obvious and graphic way of identifying this distinction is to compare the position of
a sovereign state with that of a territory which is part of a federal state. Thus
Iceland is a sovereign state; Texas is not. It is her constitutional independence which,
in international practice, is deemed to confer sovereignty on Iceland, and so make
her eligible for full international actorhood. By contrast, non-sovereign territorial
entities do not enjoy such actorhood, and most have none whatsoever.
The post-international challenge to foreign policy: signposting ‘plus non-state’ politics
Authors: Chong Alan
Published: November 2002

To scholars researching the connections between international relations and globalisation, such as those in the five books reviewed here, ‘foreign policy’ is becoming functionally and descriptively rivalled in a globalising context. Foreign policy, once the theoretically exclusive prerogative of the nation-state, is violated daily by new developments in non-state actorness arising from transnational technical and welfare issues such as trade, finance, labour standards and environmentalism. These books under review introduce the displacement lexicon of transnational politics, global civil society, non-state resistance and complexity into policymaking consciousness; in short, the post-international era. The conclusion proposes to tease out the preliminary outlines of the post-international challenge to foreign policy on the basis of ‘plus non-state’ actor-interest considerations.
Law, the ‘commune’, and the distribution of resources in early modern German state formation
Authors: WARDE PAUL
Published: November 2002

This article examines a series of disputes that developed among villagers in the Duchy of Württemberg in south-west Germany during the sixteenth and early seventeenth centuries, disputes that were appealed to higher courts and became a matter for decision by the Duchy's ruling council. The disputes concerned the allocation of free wood from communally owned woodlands, and the size of shares permitted to particular groups, but developed into arguments over the nature of communal government and the authority of custom. They provide avenues to the understanding of the development of intra-village tensions, and to how disputes over resource allocation could erupt at particular instances, drawing higher echelons of state authority into the resolution of essentially local problems. In doing so the article seeks to provide a corrective to simplistic explanations of why resource regulation occurs at particular junctures, and contributes to a history of state formation, the village commune and legal change, giving proper place to pressures ‘from below’ as well as government intervention.
The Justinianic plague: origins and effects
Authors: SARRIS PETER
Published: November 2002

This article addresses the subject of the first well-attested outbreak of bubonic plague in the history of the Mediterranean world – the so-called ‘Justinianic Plague’ of the sixth century. The African origin of the disease is examined and contextualized, whilst recent revisionist arguments in relation to the scale of the depopulation caused by the plague are responded to with reference to the numismatic, legal, and papyrological sources. The numismatic evidence in particular points to a major crisis in imperial finances for which large-scale depopulation would be the most likely cause. The legal and papyrological sources record how both landowners and the imperial authorities responded to this situation.
Merchant households and their networks in eighteenth-century Trondheim
Authors: BULL IDA
Published: November 2002

This article deals with merchants in international trade from the seventeenth and into the nineteenth century, most of them of immigrant background. Based on a discussion of the work of the household in gender terms the main point is to show how the merchants were eager to construct working network relations. Family and kinship relations are discussed as a crucial element in the merchants' networks, and throughout their world of household, regional contact networks and international networks run structures of hierarchical and patriarchal authority and at the same time non-hierarchical relations of equality.
Nuclear hardship or variant dependency? Households and the Scottish Poor Law
Authors: BLAIKIE ANDREW
Published: November 2002

The ‘nuclear hardship’ hypothesis claims that where nuclear families predominated collective aid prevailed, whereas extended households were co-extensive with kin-based support. This article tests this assumption by considering the relationship between households and the Poor Law in Lowland Scots communities after 1845. While cross-sectional census data are inconclusive, a longitudinal analysis based on case study evidence, including temporary as well as permanent relief patterns, suggests that ‘nuclear hardship’ might be replaced by a model that matches household structure with the varying sources of aid given during critical life situations while focusing upon applicants as negotiators rather than victims.
The budget of a Corsican stem family
Authors: MARCHINI ANTOINE
Published: November 2002

This article provides a detailed analysis of the income and expenditure of a stem family household from Bastelica, Corsica, based on information collected in 1867 and 1887 according to the scheme recommended by Frédéric Le Play. The budget indicates the work undertaken by each member of the family and which economic activities were most valuable to the family in terms of the income they generated and the level of profit. The primary resource of the family was its members, as the family used almost no non-family labour. The composition of the household, and the distribution of its members in terms of age and sex, were therefore critical for its economic well-being. Members of the family contributed their labour according to their sex, age and place within the household. Males were better paid than females but each son received more than his father and the daughters were better paid than their mother. Apart from the father, the less well paid the family member, the longer the time they were at work. In addition, the two highly paid sons were unemployed for more than half of the year. This provided a reserve of labour in the event of a rise in the ratio of consumers to workers within the family. The economy of the family was based on the exploitation of its patrimony and on animal husbandry. Food constituted the largest single item of expenditure but the diet of this family did not provide the 2,800 calories of the average diet in France between 1855 and 1874.
A homotopy construction of the adjoint representation for Lie groups
Authors: CASTELLANA NATÀLIA , KITCHLOO NITU
Published: November 2002

Let G be a compact, simply-connected, simple Lie group and T ⊂ G a maximal
torus. The purpose of this paper is to study the connection between various fibrations over BG (where G is a compact, simply-connected, simple Lie group) associated to the adjoint representation and homotopy colimits over poset categories [Cscr ],
hocolim[Cscr ]BGI where GI are certain
connected maximal rank subgroups of G.
Hausdorff–Besicovitch measure for random fractals of Chung's type
Authors: LUCAS ALAIN
Published: November 2002

Let {W(t):t [ges ] 0} denote a Wiener process, and set [Sscr ] for the unit ball
of the reproducing kernel Hilbert space pertaining to the restriction of W on
[0,1], with Hilbert norm [mid ] · [mid ]H. Gorn and Lifshits
[8] have shown that, whenever f ∈ [Sscr ] fulfills
[mid ] f [mid ]H = 1 and has Lebesgue derivative of
bounded variation, the rate of clustering of
(2h log(1/h))−½(W(t + h·)
− W(t)) to f is of the order
O((log(1/h))−2/3. In this paper, we show that the set of
exceptional points in [0,1] where this rate is reached
constitutes a random fractal whose Hausdorff–Besicovitch measure is evaluated.
Explicit homotopy equivalences in dimension two
Authors: JOHNSON F. E. A.
Published: November 2002

Let G be a finite group; by an algebraic 2-complex over G we mean an exact
sequence of Z[G]-modules of the form:

E = (0 → J → E2 → E1 → E0 → Z → 0)

where Er is finitely generated free over Z[G] for 0 [les ] r [les ] 2. The module J is determined up to stability by the fact of appearing in such an exact sequence; we denote
its stable class by Ω3(Z); E is said to be minimal when rkZ(J) attains the minimum
possible value within Ω3(Z).
Non-commutative notions of stochastic independence
Authors: BEN GHORBAL ANIS , SCHÜRMANN MICHAEL
Published: November 2002

We present, starting from a set of canonical axioms, a complete classification of the
notions of non-commutative stochastic independence. Our result originates from a
first contribution and a conjecture by M. Schürmann and is based on a fundamental
paper by R. Speicher.
Hypercomplex manifolds and hyperholomorphic bundles
Authors: FEIX BIRTE
Published: November 2002

Using twistor techniques we shall show that there is a hypercomplex structure
in the neighbourhood of the zero section of the tangent bundle TX of any complex
manifold X with a real-analytic torsion-free connection compatible with the complex
structure whose curvature is of type (1, 1). The zero section is totally geodesic and
the Obata connection restricts to the given connection on the zero section.

We also prove an analogous result for vector bundles: any vector bundle with real-analytic connection whose curvature is of type (1, 1) over X can be extended to a
hyperholomorphic bundle over a neighbourhood of the zero section of TX.
The centric p-radical complex and a related p-local geometry
Authors: SAWABE MASATO
Published: November 2002

We shall introduce a p-local geometry Δp(G) for the pair (G, p) of a finite group G
and a prime divisor p of the order of G, which is constructed by ‘maximal parabolic
like’ subgroups of G. Under the natural hypothesis, Δp(G) behaves very much like
the building associated with a group of Lie type in characteristic p. We shall also
show that, under some hypothesis, Δp(G) is homotopy equivalent to the subgroup
complex [Bscr ]cenp(G) which is a more essential part of the p-radical complex [Bscr ]p(G). Some
of the p-local sporadic geometries can be understood well in our system.
Empirical multifractal moment measures and moment scaling
functions of self-similar multifractals
Authors: OLSEN L.
Published: November 2002

Let Si: ℝd → ℝd for i = 1, …, n be contracting similarities, and let (p1, …, pn) be
a probability vector. Let K and μ be the self-similar set and the self-similar measure
associated with (Si,pi)i. For q ∈ ℝ and r > 0, define the qth covering moment and
the qth packing moment of μ by

[formula here]

where the infimum is taken over all r-spanning subsets E of K, and the supremum
is taken over all r-separated subsets F of K. If the Open Set Condition (OSC) is
satisfied then it is well known that

[formula here]

where β(q) is defined by
[sum ]ipqirβi(q) = 1 (here ri denotes the Lipschitz constant of Si).
Assuming the OSC, we determine the exact rate of convergence in (*): there exist
multiplicatively periodic functions πq, Πq: (0,∞) → ℝ such that

[formula here]

where ε(r) → 0 as r[searr ]0. As an application of (**) we show that the empirical multi-fractal moment measures converges weakly:

[formula here]

where, for each positive r, Er is a (suitable) minimal r-spanning subset of K and
Fr is a (suitable) maximal r-separated subset of K, and
[Hscr ]q,β(q)μ and [Pscr ]q,β(q)μ
are the
multifractal Hausdorff measure and the multifractal packing measure, respectively.
Bernstein and Markov-type inequalities for polynomials on real Banach spaces
Authors: MUÑOZ GUSTAVO A. , SARANTOPOULOS YANNIS
Published: November 2002

In this work we generalize Markov's inequality for any derivative of a polynomial
on a real Hilbert space and provide estimates for the second and third derivatives
of a polynomial on a real Banach space. Our result on a real Hilbert space answers
a question raised by L. A. Harris in his commentary on problem 74 in the Scottish
Book [20]. We also provide generalizations of previously obtained inequalities of the
Bernstein and Markov-type for polynomials with curved majorants on a real Hilbert space.
Explicit concave fillings of contact three-manifolds
Authors: GAY DAVID T.
Published: November 2002

Suppose that (X,ω) is a symplectic manifold and that there exists a Liouville
vector field V defined in a neighbourhood of and transverse to M = ∂X. Then V
induces a contact form α = ιVω[mid ]M on M which determines the germ of ω along M.
One should think of the contact manifold (M,ξ = ker α) as controlling the behaviour
of ω ‘at infinity’. If V points out of X along M then we call (X,ω) a convex filling of
(M,ξ), and if V points into X along M then we call (X,ω) a concave filling of (M,ξ).
Technical Extracts from the Memoirs of Dr. J. A. Pierce
Authors: Blanchard Walter F.
Published: November 2002

The following is the third and final part of an extract from the memoirs of Dr. J. A. Pierce who was deeply involved in the development of radionavigation aids in the USA between 1941 and 1973. These are, of course, personal reminiscences, and some issues might be challenged by others working in the same field at the time. However, they give a remarkable insight into the problems faced by the scientists of the day and how they were overcome. This final part deals almost exclusively with the development of the Omega Navigation System, which was the first truly ‘global’ navigation system to enter service. The editing principle used here has been to preserve Dr. Pierces' own wording while eliminating those parts of a purely personal nature. The entire original document without cuts may be found on www.internationalnavigation.org
The ‘ALVA CAPE’ and the Automatic Identification System: The Use of VHF in Collision Avoidance at Sea
Authors: Harding S. J.
Published: November 2002

One of the most controversial issues relating to marine navigation is the efficacy of ships' crews using VHF radio technology for bridge-to-bridge communications to agree manoeuvres. Through a re-evaluation of historic case studies, this paper provides background on the development of applying VHF technology in collision avoidance and the legislation, national and international, underpinning the practice; a practice that has found little or no support from the legal establishment. Finally the consequential development of a policy to require specific VHF technology to be installed on ships to facilitate agreements in relation to collision avoidance manoeuvres will be reviewed, that is the Automatic Identification System (AIS).

Integrity without knowledge is weak and useless, and knowledge without integrity is dangerous and dreadful. Samuel Johnson
The COLREGS – Time for a Rewrite?
Authors: Stitt I. P. A.
Published: November 2002

It is 30 years since major changes were last made to the collision regulations. This paper identifies a number of shortcomings in the current Rules, including excessive verbiage, unnecessary duplications and complications, and the use of weasel words. It also examines the use that has been made of Rule 2 in broadening the interpretation of other Rules. Proposals are then put forward for rewriting The Rules so as to improve their clarity and hopefully their understanding. The paper is written from the viewpoint of a mariner.
Civil Marine Radar – A Fresh Look at Transmitter Spectral Control and Diversity Operation
Authors: Williams P. D. L.
Published: November 2002

This year marks a watershed in the design, production and operational use of Civil Marine Radar (CMR) as we know it. Tighter regulations for in-band spectral purity and out-of-band transmission, when coupled to a possible loss of S-band frequencies for both CMR and Air Traffic Control (ATC) radars, will seriously restrict the synergistic advantage of dual-band systems, as well as the form of new RF heads. There is a conflict of IMO requirements to still retain simple pulse radars to activate Racons and SARTS while also meeting these new stringent spectral regulations. Options are given for serious discussion amongst all concerned before it is too late.
Altitude Aiding for GPS Systems using Elevation Map Datasets
Authors: Ptasinski P. , Cecelja F. , Balachandran W.
Published: November 2002

This paper reports the development of a DGPS navigation system integrated with altitude aiding. In this system, a digital height dataset is used for altitude augmentation. A two-dimensional (2-D) positioning algorithm is discussed and modified based on previous publications. The developed algorithm was implemented on the Brunel Inverse DGPS system. The performance of the new developed system is experimentally verified and compared with three-dimensional (3-D) GPS and DGPS systems. The experimental results showed 86% availability of positioning services; whereas for the 3-D GPS system alone, the availability was only 63% of time. In addition, the accuracy of the system was improved from 7.1 to 6.1 m (RMS) for GPS and from 6.0 to 5.1 m (RMS) for DGPS when compared to standalone 3-D modes.
The Usefulness of GLONASS for Positioning in the Presence of GPS in the Indian Subcontinent
Authors: Banerjee P. , Bose Anindya , Dasgupta Ashish
Published: November 2002

The effort to integrate the use of GPS and GLONASS constellations resulted in the production of a special receiver, which can use both constellations in combination. These receivers may be used in GPS only mode, GLONASS mode and combined (both GPS and GLONASS) mode. Utilising this type of receiver, GPS and GLONASS signals were monitored for one calendar year simultaneously in different places in India to study the status of visibility of satellites and the positioning accuracy. The number of satellites in GLONASS constellation gradually depleted from 16 to 7 during the course of this study. So a 3-D solution was rarely possible using only GLONASS satellites. However, appreciable improvement in PDOP was observed in the combined mode. Before the withdrawal of GPS Selective Availability (SA), significant improvement of position accuracy could be observed in the combined mode. After the removal of GPS-SA, the accuracies of the combined mode and that of GPS-only mode have been found to be of the same order. While this does not apparently reflect any advantage, it indirectly confirms that both the GPS and the GLONASS systems have similar limits of accuracy and also confirms that optimal interoperability of two systems has been achieved. These studies reveal that the combined use of GLONASS and GPS will always be beneficial to a varying degree depending on different applications and circumstances.
Geomatics Aspects of the UN Convention on Law of the Sea – A Case Study
Authors: El-Rabbany Ahmed
Published: November 2002

The United Nations Convention on Law of the Sea (UNCLOS) came into force on November 18, 1994 to provide the legal framework for maritime boundary delimitation. Understanding the geomatics aspects of UNCLOS is vital for coastal nations to claim the ownership of the natural resources within the limits of their Continental Shelf. This paper discusses some of the geomatics aspects of UNCLOS, namely the geodetic and uncertainty issues. A case study for Egypt's outer limits is also presented.
Distributed Positioning: A Network-Supported Method for Satellite Positioning Performance Improvement
Authors: Filjar Renato , Huljenić Darko , Dešić Saša
Published: November 2002

Recent studies show that basic satellite positioning is reaching its limits in terms of performance improvements. Further enhancements in positioning performance can be based almost entirely on augmentation and procedures supported by other systems. Considering the complexity of the interrelationship with additional systems, intrinsically different solutions are being developed to solve the positioning performance improvement problem. Here we present a new concept in positioning. Dubbed distributed positioning, it merges basic satellite positioning with advanced and assisted positioning procedures. The resulting complex synergy unavoidably includes the use of additional technologies in mobile communications, wireless Internet, and advanced computer systems. The real advantage from the introduction of distributed positioning lies in its capability to provide a significant improvement in overall positioning performance. Latest navigation status and up-to-date local environment models are much easier to apply on rover positioning, compared with classical assisted-GPS positioning procedures. Distributed positioning presents a completely different approach in positioning performance improvement, opening new prospects in research and development not only in the field of the satellite positioning, but also in telecommunications and computer engineering.
Crossing scales: Howard T. Odum
Authors: McClanahan T.R.
Published: November 2002

One of the founders of modern ecology, environmental science, ecological engineering and economics, H.T. Odum, passed away on 11 September 2002 in Gainesville, Florida, from cancer at the age of 78. He died less than a month after the death of his older brother and long-time collaborator, Eugene P. Odum. The two brothers published the classic ecological textbook of the early 1950s (Odum 1953; H.T. Odum's role was not credited until an acknowledgement page in the 3rd edition, published in 1971), one of the first modern holistic views of ecology, ecosystems and human impacts. Among numerous other prizes and awards, they jointly won the Crafoord Prize in 1987, equivalent to a Nobel Prize in ecology, and the Prize of the Institut de la Vie in Paris in 1976. Howard Odum produced 15 books, nearly 300 articles and was chairman for nearly 100 doctoral dissertations of which 75 were during his tenure at the University of Florida from 1970. His students are leaders in many fields of environmental science. His ashes were scattered in the Howard T. Odum Memorial Cypress Swamp, a cypress dome near the University of Florida campus that he donated to the University for research purposes.
Geoconservation and protected areas
Authors: Brilha José
Published: November 2002

Introduction

In most countries, protected area managers are primarily interested in biology (McNeely & Miller 1984; Nelson & Serafin 1997). This perspective is not suitable for effective nature conservation because there is no real separation between geological and biological processes. Geology is important in all kinds of planning projects because geology is part of all natural systems. Understanding of climate, landforms and biodiversity depends on geological studies. Even human habitation and cultural heritage depend on geology. During the last 30 years, numerous studies have shown that biological conservation is essential to the welfare of all human beings. Nevertheless, the concept of geoconservation and preservation of the geological heritage has appeared only recently (Wilson 1994; Sharples 1998; Barettino et al. 1999, 2000; Osborne 2000).

I argue that real nature conservation can only be attained if geology is integrated into protected area management at the same level of importance as biology and all natural processes are considered together.
Impacts of birdwatching on human and avian communities
Authors: Sekercioglu Cagan H.
Published: November 2002

Ecotourism can be a vehicle for community-based conservation if it is conducted with an emphasis on the well-being of local ecosystems and human communities. Birdwatchers form the largest group of ecotourists, and are, on average, well-educated, wealthy and committed. This makes them ideal ecotourists for community-based conservation. Therefore, there is a need for a comprehensive review of birdwatching from a conservation biology perspective. Specific objectives here are: (1) to review the economic potential of non-residential birdwatching for community-based conservation; (2) to outline the potential benefits and problems associated with this activity; and (3) to provide suggestions for improving the conservation value of birdwatching. Birdwatching tourism has a high potential to improve the financial and environmental well-being of local communities, educate locals about the value of biodiversity and create local and national incentives for successful protection and preservation of natural areas. However, there needs to be more research on the economical and environmental impacts of this hobby, birdwatching-related disturbance needs to be reduced, and much has to be done to increase the financial contribution of birdwatching to local communities.
Environmental issues in lakes and ponds: current state and perspectives
Authors: Brönmark Christer , Hansson Lars-Anders
Published: November 2002

Lakes and ponds are habitats of great human importance as they provide water for domestic, industrial and agricultural use as well as providing food. In spite of their fundamental importance to humans, freshwater systems have been severely affected by a multitude of anthropogenic disturbances, which have led to serious negative effects on the structure and function of these ecosystems. The aim of the present study is to review the current state of lake and pond ecosystems and to present a likely scenario for threats against these ecosystems for the time horizon of the year 2025. Predictions are based on a review of the current state, projections of long-term trends, for example in population and global climate, and an analysis of the trends in publications in the scientific literature during the past 25 years (1975–2000). The biodiversity of lake and pond ecosystems is currently threatened by a number of human disturbances, of which the most important include increased nutrient load, contamination, acid rain and invasion of exotic species. Analysis of trends suggests that older, well known threats to biodiversity such as eutrophication, acidification and contamination by heavy metals and organochlorines may become less of a problem in developed countries in the future. New threats such as global warming, ultraviolet radiation, endocrine disruptors and, especially, invasion by exotic species including transgenic organisms will most likely increase in importance. However, in developing countries where priorities other than environmental conservation exist, the threat of eutrophication, acidification and contamination by toxic substances is predicted to continue to increase. Although the future of biodiversity in lakes and ponds is seriously threatened, growing concern for environmental problems, implementation of new environmental strategies and administrations, and international agreements, are positive signs of changes that should improve the ability to manage old as well as new, yet undiscovered, threats.
Present state and future of the world's mangrove forests
Authors: Alongi Daniel M.
Published: November 2002

Mangroves, the only woody halophytes living at the confluence of land and sea, have been heavily used traditionally for food, timber, fuel and medicine, and presently occupy about 181 000 km2 of tropical and subtropical coastline. Over the past 50 years, approximately one-third of the world's mangrove forests have been lost, but most data show very variable loss rates and there is considerable margin of error in most estimates. Mangroves are a valuable ecological and economic resource, being important nursery grounds and breeding sites for birds, fish, crustaceans, shellfish, reptiles and mammals; a renewable source of wood; accumulation sites for sediment, contaminants, carbon and nutrients; and offer protection against coastal erosion. The destruction of mangroves is usually positively related to human population density. Major reasons for destruction are urban development, aquaculture, mining and overexploitation for timber, fish, crustaceans and shellfish. Over the next 25 years, unrestricted clear felling, aquaculture, and overexploitation of fisheries will be the greatest threats, with lesser problems being alteration of hydrology, pollution and global warming. Loss of biodiversity is, and will continue to be, a severe problem as even pristine mangroves are species-poor compared with other tropical ecosystems. The future is not entirely bleak. The number of rehabilitation and restoration projects is increasing worldwide with some countries showing increases in mangrove area. The intensity of coastal aquaculture appears to have levelled off in some parts of the world. Some commercial projects and economic models indicate that mangroves can be used as a sustainable resource, especially for wood. The brightest note is that the rate of population growth is projected to slow during the next 50 years, with a gradual decline thereafter to the end of the century. Mangrove forests will continue to be exploited at current rates to 2025, unless they are seen as a valuable resource to be managed on a sustainable basis. After 2025, the future of mangroves will depend on technological and ecological advances in multi-species silviculture, genetics, and forestry modelling, but the greatest hope for their future is for a reduction in human population growth.
The continental shelf benthic ecosystem: current status, agents for change and future prospects
Authors: Hall Stephen J.
Published: November 2002

Continental shelf benthic ecosystems play an important role in the economy of many coastal states through the provision of food, non-living resources and through control of climate. Changes in the status of these ecosystems, through either natural or human-induced environmental drivers can be expected to have important economic and social consequences. Agents that could induce change include climate and oceanography, hydrology (river discharge), land-use and waste disposal practices, fishing, aquaculture and extraction of non-living resources. Trends in all of these drivers, particularly those under human influence, suggest that shelf systems will come under increasing pressure. Attempts to predict the future state of any ecological system are fraught with difficulty, particularly over decadal time-frames. This is, perhaps, especially true for continental shelf ecosystems where data on current status are poor and our understanding of many of the drivers of change somewhat rudimentary. What can be said for certain, however, is that change will occur and, in the short term, many of the signs point towards deterioration in the ecological condition of many shelf systems, but particularly those of developing countries. Trends in land-use practices, with consequences for nutrient, sediment and freshwater input to coastal seas appear to be particularly worrying, but the poor state of many demersal fisheries systems must also be acknowledged. In contrast to the developing world, although challenges undoubtedly remain, particularly with respect to atmospheric inputs resulting from energy production, current trends in environmental management suggest that pressures imposed by land use, waste disposal and fishing will probably decline over the coming decades on the shelves of many developed countries. At the global scale, therefore, the key driver for sustainable use of our continental shelf ecosystems would appear to be intimately linked to the social and economic well-being of poorer nations.
Wildlife harvesting, conservation and poverty: the economics of olive ridley egg exploitation
Authors: Hope Robert Adrian
Published: November 2002

Eggs of the olive ridley marine turtle (Lepidochelys olivacea) have been harvested by generations of Pacific coast communities in Central America for both economic and nutritional reasons. There has been little economic analysis that has identified possible points of improvements for management of the resource. Three egg harvesting projects were studied in Costa Rica and Nicaragua. Field research using semi-structured interviews with stakeholders and key informants were undertaken in June and July 2000. Market price data were collected from harvesters, points of sale and government records. Spread price analysis suggested that more flexible seasonal and regional pricing policies might increase egg profits. Contested property rights have weakened incentives to manage the species as an asset rather than an open access resource. Transaction costs have reduced community efficiency in egg marketing. Community egg marketing cartels with authorized urban selling points are recommended to improve resource management, appropriate a higher egg profit margin and clarify the harvesting origin of eggs for consumers.