Search

In this research, the controversial issue of whether the central bottleneck can be bypassed through task automatization was investigated. To examine this issue, participants received six single-task practice sessions with an auditory-vocal task (low vs. high pitch). We then assessed dual-task performance using the analytically tractable psychological refractory period (PRP) paradigm, in which the highly practiced auditory-vocal task was presented as Task 2, along with an unpracticed visual-manual Task 1. The results provide evidence of bottleneck bypass for virtually all the participants (17 out of 20). Several converging tests suggest that the bottleneck reemerged, however, in a follow-up experiment with tasks presented in the opposite order (auditory-vocal Task l and visual-manual Task 2). One possible explanation is that tasks greedily recruit central resources when available, even though they can operate without central resources when unavailable.

When juvenile mortality or juvenile growth is impacted by temperature and salinity, these factors have a substantial effect on recruitment success and population dynamics in benthic ecosystems. Using freshly settled cyprids of Amphibalanus improvisus, we investigated the combined effects of temperature (12, 20 and 28°C) and salinity (5, 15 and 30 psu) on early juvenile stage performance. Mortality as well as size (basal diameter, dry weight, and ash-free dry weight) was monitored for a period of 40 days. Mortality was high (42-63%) during the first week following attachment, regardless of the temperature and salinity treatments. Subsequently, mortality and size were interactively influenced by temperature and salinity. Highest mortality and lowest size of juveniles occurred at lowest temperature (12°C) and salinity (5 psu). Apparently, low temperature (12°C) narrowed the barnacles' salinity tolerance. Juvenile barnacles constructed more shell material compared to body mass at high temperature and high salinity, while a reverse situation was observed at low temperature and low salinity. Our results demonstrate that environmental changes can directly and/ or indirectly alter patterns of survivorship and size. Warming and desalination as predicted for the Baltic Sea in the course of climate change may, however, act antagonistically and compensate each other's isolated effect on barnacles., Introduction Barnacle ontogeny shows a complex life cycle in which the nauplius larva molts six times before transforming into the cypris stage. The competent cyprid explores the potential settlement substratum [...]

Shelters generated by the introduced reef-building polychaete Ficopomatus enigmaticus (Serpulidae) significantly enhance settlement of the crab Cyrtograpsus angulatus (Grapsidae) in a SW Atlantic coastal lagoon (Mar Chiquita, 37[degrees]32'S; 57[degrees]26'W; Argentina). However, their ultimate role in recruitment does not appear to be very important, suggesting a habitat-generated bottleneck that occurs between settlement and recruitment. Laboratory and field experiments show that newly settled crabs actively select refuges similar in size. Inside the reefs, decreases in crab density of each newly settled cohort mirror the ratio of decreases in the number of reef refuges of similar sizes, suggesting that habitat fractal structure determines the mortality rate after settlement. Field experiments using artificial shelters show that as crabs increase in size, they move outside reefs. Field tethering of juvenile- and adult-sized crabs without access to refuges showed that juvenile crabs suffer a much higher risk of mortality than adults. Our results show that the availability of small refuges provided by polychaete reefs enhances crab settlement, but, then, due to a decrease in the number of refuges as size increases, produces a demographic bottleneck during recruitment. Thus, independent of settlement intensity, enhanced survivorship in the smallest size classes due to refuge is not transmitted to larger size classes. This is likely one reason why stock-recruitment relationships may not hold in species that use shelters during both recently settled and juvenile life stages. These results provide a good example of why habitat enhancement programs need to incorporate a comprehensive evaluation of the species' ontogenic ecology to avoid class size-specific bottlenecks.

Byline: Jerome Monnot (1), Olivier Spanjaard (1) Keywords: Shortest path; partial order; algebraic methods; bottleneck problems Abstract: In bottleneck combinatorial problems, admissible solutions are compared with respect to their maximal elements. In such problems, one may work with an ordinal evaluation scale instead of a numerical scale. We consider here a generalization of this problem in which one only has a partially ordered scale (instead of a completely ordered scale). After the introduction of a mappimax comparison operator between sets of evaluations (which boils down to the classical operator when the order is complete), we establish computational complexity results for this variation of the shortest path problem. Finally, we formulate our problem as an algebraic shortest path problem and suggest adequate algorithms to solve it in the subsequent semiring. Author Affiliation: (1) LAMSADE - Universite Paris Dauphine, Place du Marechal De Lattre de Tassigny, 75775, Paris Cedex 16, France Article note: Received: June 2002, Revised: March 2003, AMS classification: Olivier Spanjaard: Corresponding author.

Byline: ZBIGNIEW BANASZAK (1) Keywords: Repetitive process; job shop; dispatching rule; distributed control; bottleneck Abstract: A bottleneck control problem for general periodic job shops with blocking where each machine has an input buffer of finite capacity is investigated. The job shop considered consists of a set of workflows competing with each other for access to common machines. A distributed buffer control policy that restricts a job entering an input buffer of a local machine in a specific sequence is proposed. The conditions sufficient for design and allocation of dispatching rules are presented. The system time and the rate of machine utilization are considered as the evaluation criteria. Finally, the procedure aimed at scheduling periodic job shops is provided. Author Affiliation: (1) Institute of Robotics and Software Engineering, Technical University of Zielona GoA'ra, ul, PodgoA'rna 50, 65-246, Zielona GoA'ra, Poland Article History: Registration Date: 09/09/2004

Greater competition within an industry can decrease prices for customers. Various examples within the US telecommunications industry are provided.

In two studies, we find that native and non-native acquisition show different effects on sign language processing. Subjects were all born deaf and used sign language for interpersonal communication, but first acquired it at ages ranging from birth to 18. In the first study, deaf signers shadowed (simultaneously watched and reproduced) sign language narratives given in two dialects, American Sign Language (ASL) and Pidgin Sign English (PSE), in both good and poor viewing conditions. In the second study, deaf signers recalled and shadowed grammatical and ungrammatical ASL sentences. In comparison with non-native signers, natives were more accurate, comprehended better, and made different kinds of lexical changes; natives primarily changed signs in relation to sign meaning independent of the phonological characteristics of the stimulus. In contrast, non-native signers primarily changed signs in relation to the phonological characteristics of the stimulus independent of lexical and sentential meaning. Semantic lexical changes were positively correlated to processing accuracy and comprehension, whereas phonological lexical changes were negatively correlated. The effects of non-native acquisition were similar across variations in the sign dialect, viewing condition, and processing task. The results suggest that native signers process lexical structure automatically, such that they can attend to and remember lexical and sentential meaning. In contrast, non-native signers appear to allocate more attention to the task of identifying phonological shape such that they have less attention available for retrieval and memory of lexical meaning.

The persistence diagram is an increasingly useful tool from Topological Data Analysis, but its use alongside typical machine learning techniques requires mathematical finesse. The most success to date has come from methods that map persistence diagrams into vector spaces, in a way which maximizes the structure preserved. This process is commonly referred to as featurization. In this paper, we describe a mathematical framework for featurization called template functions, and we show that it addresses the problem of approximating continuous functions on compact subsets of the space of persistence diagrams. Specifically, we begin by characterizing relative compactness with respect to the bottleneck distance, and then provide explicit theoretical methods for constructing compact-open dense subsets of continuous functions on persistence diagrams. These dense subsets-obtained via template functions-are leveraged for supervised learning tasks with persistence diagrams. Specifically, we test the method for classification and regression algorithms on several examples including shape data and dynamical systems., Author(s): Jose A. Perea [sup.1], Elizabeth Munch [sup.2], Firas A. Khasawneh [sup.3] Author Affiliations: (1) grid.261112.7, 0000 0001 2173 3359, Department of Mathematics and Khoury College of Computer Sciences, Northeastern [...]

The challenge of long-term interaction between humans and robots is still a bottleneck in service robot research. To gain an understanding of sustained relatedness with robots, this study proposes a conceptual framework for bond formation. More specifically, it addresses the dynamics of children bonding with robotic pets as the basis for certain services in healthcare and education. The framework presented herein offers an integrative approach and draws from theoretical models and empirical research in Human Robot Interaction and also from related disciplines that investigate lasting relationships, such as human-animal affiliation and attachment to everyday objects. The research question is how children's relatedness to personified technologies occurs and evolves and what underpinning processes are involved. The subfield of research is child-robot interaction, within the boundaries of social psychology, where the robot is viewed as a social agent, and human-system interaction, where the robot is regarded as an artificial entity. The proposed framework envisions bonding with pet-robots as a socio-affective process towards lasting connectedness and emotional involvement that evolves through three stages: first encounter, short-term interaction and lasting relationship. The stages are characterized by children's behaviors, cognitions and feelings that can be identified, measured and, maybe more importantly, managed. This model aims to integrate fragmentary and heterogeneous knowledge into a new perspective on the impact of robots in close and enduring proximity to children., Author(s): Marta Díaz-Boladeras [sup.1] [sup.2] Author Affiliations: (1) Technical Research Centre for Dependency Care and Autonomous Living (CETpD), , Rambla Exposició, 59., 08800, Vilanova i la Geltrú, Spain (2) grid.6835.8, [...]

The Cape fur seal, Arctocephalus pusillus pusillus is distributed along the southern African coastline from northern Namibia to the south-east coast of South Africa. The species has been impacted by sealing operations since the 1600s, and historical records suggest that the taxon experienced a bottleneck prior to the 20th century. Mitochondrial DNA control region sequences were generated for 106 individuals belonging to six breeding colonies. Haplotype diversity was found to be high (0.975 [+ or -] 0.014) whereas levels of nucleotide diversity were much lower compared to other seal species (0.011 [+ or -] 0.006). An analysis of molecular variance indicated that the largest percentage of haplotype diversity is distributed within colonies rather than among them. This could be attributed to either extensive gene flow among colonies, a lack of substantial female site philopatry, or incomplete lineage sorting of haplotypes. Mismatch distribution and Fu's [F.sub.S] test indicated that the population has experienced a historical population expansion probably between c. 37,000-18,000 YBP and this date coincides very well with the height of the last glacial maximum when food resources were abundant in the South Atlantic. These results also suggest that the recent sealing-induced bottleneck did not have a profound influence on the haplotype diversity and a historical bottleneck prior to a demographic expansion may have been severe enough to reduce nucleotide diversity substantially., Introduction The fur seal, Arctocephalus pusillus, has a disjunct distribution in the southern hemisphere and two subspecies have been recognized. The Cape fur seal, A. p. pusillus, occurs along the [...]

The level of habitat availability influences genetic divergence among populations and the genetic diversity within populations. In the marine environment, near-shore species are among the most sensitive to habitat changes. Knowledge of how historical environmental change affected habitat availability and genetic variation can be applied to the development of proactive management strategies of exploited species. Here, we modeled the contemporary and historical distribution of Lutjanus jocu in Brazil. We describe patterns of genomic diversity to better understand how climatic cycles might correlate with the species demographic history and current genetic structure. We show that during the Last Glacial Maximum, there were ecological barriers that are absent today, possibly dividing the range of the species into three geographically separated areas of suitable habitat. Consistent with a historical reduction in habitat area, our analysis of demographic changes shows that L. jocu experienced a severe bottleneck followed by a population size expansion. We also found an absence of genetic structure and similar levels of genetic diversity throughout the sampled range of the species. Collectively, our results suggest that habitat availability changes have not obviously influenced contemporary levels of genetic divergence between populations. However, our demographic analyses suggest that the high sensitivity of this species to environmental change should be taken into consideration for management strategies. Furthermore, the general low levels of genetic structure and inference of high gene flow suggest that L. jocu likely constitutes a single stock in Brazilian waters and, therefore, requires coordinated legislation and management across its distribution., Author(s): Julia Tovar Verba [sup.1] [sup.2] [sup.3] [sup.4] , Adam Stow [sup.2] , Bernhard Bein [sup.3] , Maria Grazia Pennino [sup.4] [sup.5] , Priscila F. M. Lopes [sup.1] [sup.4] , [...]

Byline: MICHAEL C. FU (1), JEFFREY W. HERRMANN (2), MURALI NARAYANASWAMY (1) Keywords: Work order release; perturbation analysis; job shop control Abstract: In job shop manufacturing environments, controlling the release of work orders can significantly improve system performance, especially when a few bottleneck resources limit shop throughput. A periodic order release policy measures the remaining workload of the bottlenecks and releases just enough work orders to bring the workload to specified threshold values. The thresholds should limit the work-in-process inventory but not delay order completion by starving the bottlenecks. In this paper we consider the problem of setting thresholds that minimize the expected cost of work-in-process inventory and order tardiness. For the single-bottleneck system, we propose a stochastic optimization approach that uses smoothed perturbation analysis to estimate the objective function gradient. Our computational experiments compare different methods that set good threshold values and show that periodic order release improves system performance. Author Affiliation: (1) College of Business and Management, Institute for systems Research, University of Maryland, College Park, MD, 20742, USA (2) Department of Mechanical Engineering, Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA Article History: Registration Date: 09/09/2004

Classic of Changes is a Chinese cultural classic born more than 3000 years ago. Its profound philosophical thoughts and the use of divination have brought Classic of Changes to a strong oriental mysticism. The view of the heaven and man of yin and yang and the five elements states of Classic of Changes are completely different from the Western elemental theory of ancient Greece. The latter gave birth to classical and modern scientific theories, and the yin and yang and the eight trigrams symbol has become synonymous with oriental mysticism. In fact, the cosmology of the Holism of Classic of Changes is a precious scientific heritage of mankind. The axiomatization of the symbolic formal system of Classic of Changes aims to unveil the veil of oriental mysticism and provide oriental wisdom for the development of modern science. Transforming the symbolic system of Classic of Changes into a formal axiom system is the crystallization of the fusion of wisdom between the East and the West. The axiomatization of the symbolic formal system of Classic of Changes shows that the oriental and the western scientific tradition harmony but not sameness and there is no conflict. Classic of Changes can also be interpreted by the axiomatic system like Euclid's Elements. The main contribution of this paper is that the author skillfully uses mathematical language to formulate the system of Classic of Changes, reconstructs the ideological system of Classic of Changes with the axiomatic method and realizes the scientificalization of Chinese classical natural philosophy. The formal axiom system of Classic of Changes may give us such a revelation: the gap between the oriental and western scientific traditions is mainly in the axiomatization, but the lack of oriental scientific tradition may be the bottleneck of the development of modern science., Author(s): Xijia Wang [sup.1] Author Affiliations: (1) grid.411427.5, 0000 0001 0089 3695, College of Mathematics and Statistics, Hunan Normal University, , 410081, Changsha, China Introduction Formalization and axiomatization are the [...]

The aim of applied topology is to use and develop topological methods for applied mathematics, science and engineering. One of the main tools is persistent homology, an adaptation of classical homology, which assigns a barcode, i.e., a collection of intervals, to a finite metric space. Because of the nature of the invariant, barcodes are not well adapted for use by practitioners in machine learning tasks. We can circumvent this problem by assigning numerical quantities to barcodes, and these outputs can then be used as input to standard algorithms. It is the purpose of this paper to identify tropical coordinates on the space of barcodes and prove that they are stable with respect to the bottleneck distance and Wasserstein distances., Author(s): Sara Kalisnik [sup.1] [sup.2] Author Affiliations: (Aff1) grid.419532.8, Max Planck Institute for Mathematics in the Sciences, , Leipzig, Germany (Aff2) 0000 0001 2293 7601, grid.268117.b, Wesleyan University, , Middletown, [...]

Objectives This study aimed to determine which steps in the newborn screening collection and delivery processes contribute to delays and identify strategies to improve timeliness. Methods Data was analyzed from infants (N = 94,770) who underwent newborn screening at 83 hospitals in Michigan between April 2014 and March 2015. Linear mixed effects models estimated effects of hospital and newborn characteristics on times between steps in the process, whereas simulation explored how to improve timeliness through adjustments to schedules for the state laboratory and for specimen pickup from hospitals. Results Time from collection to receipt of arrival to the state laboratory varied greatly with collection timing (P < 0.001), with specimens collected on Friday or Saturday delayed an average of 9-12 h compared to other specimens. Simulation estimates shifting specimen pickup from 6 p.m. Sunday-Friday to 9 p.m. Sunday-Friday could lead to an additional 12.6% of specimens received by the Michigan laboratory within 60 h of birth. Conclusions for Practice The time between when a specimen is collected and received by the laboratory can be a significant bottleneck in the newborn screening process. Modifying hospital pickup schedules appears to be a simple way to improve timeliness., Author(s): Amy L. Cochran [sup.1] , Beth A. Tarini [sup.2] [sup.3] , Mary Kleyn [sup.4] , Gabriel Zayas-Cabán [sup.5] Author Affiliations: (Aff1) 0000 0001 2167 3675, grid.14003.36, Biostatistics and Medical [...]

Phylogeography provides insights into how historical and contemporary processes influence the genetic structure and gene flow in marine organisms around the globe. In benthic marine invertebrates, a species' reproductive strategy can strongly impact phylogeographic patterns and distribution, with some direct-developing (non-planktonic) dispersers demonstrating strong genetic structure but also broad geographic spread. While seemingly paradoxical, past work has shown ovoviviparous species, like Littorina saxatilis, can be more successful colonizers of remote locations than species with planktonic larvae, like L. littorea. Both Littorina species overlap in much of their North Atlantic ranges but have different colonization histories: L. saxatilis is native on both North Atlantic coasts and islands, and L. littorea is native to the eastern Atlantic but introduced to the west. Using an extensive mitochondrial dataset (1236 sequences; 85 sites), we examined how their opposing reproductive strategies correspond to their distributions and phylogeographies. Littorina saxatilis exhibited a heterogeneous genetic structure reflecting post-glacial recolonization from multiple refugial sites, while L. littorea had a homogeneous structure with a post-glacial history characterized by recolonization from one main refugial area in the northeast Atlantic. Further, haplotype diversity was significantly depressed in northwest Atlantic L. littorea populations, signifying a strong bottleneck characteristic of a human-mediated introduction. In contrast, haplotype diversity in L. saxatilis was similar between the two regions, demonstrating long-term history on both coasts. Thus, our study suggests contrasting life-history characteristics were a major structuring force in the phylogeographic patterns of these related species following large-scale disturbances (natural and anthropogenic) that compel contraction and redistribution over large areas., Author(s): April M. H. Blakeslee [sup.1] [sup.2] , A. Whitman Miller [sup.2] , Gregory M. Ruiz [sup.2] , Kerstin Johannesson [sup.3] , Carl André [sup.3] , Marina Panova [sup.3] Author [...]

The paper considers some modern problems arising in developing parallel algorithms for solving large systems of linear algebraic equations with sparse matrices occurring in mathematical modeling of real-life processes and phenomena on a multiprocessor computer system (MCS). Two main requirements to methods and technologies under consideration are fast convergence of iterations and scalable parallelism, which are intrinsically contradictory and need a special investigation. The paper analyzes main trends is developing preconditioned iterative methods in Krylov's subspaces based on algebraic domain decomposition and principles of their program implementation on a heterogeneous MCS with hierarchical memory structure. Bibliography: 24 titles., UDC 519.6 1. INTRODUCTION As is well known, solution of large Systems of Linear Algebraic Equations (SLAEs) is a bottleneck in problems of mathematical modeling because the costs of solving [...]

Ocean warming can mediate species interactions and provoke changes in community structure worldwide. Species interactions vary along environmental gradients and life-history stages and increasing temperatures may change competitive dominance between species. Kelps, being marine foundation species, have a complex heteromorphic life cycle, with the early developmental stages being a bottleneck for successful establishment of the adult population. Here, we investigated how temperature influences interactions in early life-history stages of two kelp species with different thermal affinities (Alaria esculenta and Laminaria digitata from Spitsbergen) by cultivating them in mono- and co-culture and different temperatures. Irrespectively of cultivation treatment, spore germination, gametogenesis, and sporophyte development of both species were mostly positively stimulated by a temperature increase from mean ambient summer temperatures (4-5 °C) to a global warming scenario for the Arctic future (9-10 °C) but not at 15 °C which is the southern temperature limit of A. esculenta. At 15 °C gametogenesis and sporophyte formation of A. esculenta were greatly inhibited in monoculture but not so in L. digitata. On the other hand at 5 °C and 10 °C, gametogenesis and sporophyte growth were generally faster in A. esculenta than in L. digitata, leading to a competitive advantage of A. esculenta over L. digitata in the co-cultivation treatments. The interactive effects of co-cultivation and temperature were evident, where development of A. esculenta was accelerated in the presence of L. digitata at 9 °C but not at 4 °C. Although the mechanisms triggering interspecific interactions were not determined in this study, future global warming was found to give competitive advantage of A. esculenta over L. digitata, which could affect community structure and dominance in coastal environments., Author(s): Katharina Zacher [sup.1], Miriam Bernard [sup.1] [sup.2], Alberto Daniel Moreno [sup.1], Inka Bartsch [sup.1] Author Affiliations: (1) Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, , Am Handelshafen 12, [...]

As biodiversity worldwide is decreasing, to preserve adaptive potential, the importance of maintaining species' genetic and trait diversities is increasing. An efficient foraging strategy is a critical trait for an organism's fitness, as it affects its physiology and reproduction. Understanding such strategies is especially relevant for species with long feeding migrations such as sea turtles. Using carbon and nitrogen stable isotopes combined with mitochondrial sequencing, we explored the diversity of feeding strategies in genetically differentiated nesting groups of loggerhead sea turtles (Caretta caretta) within the Cape Verde Archipelago. Here, we reveal a pattern where turtles from most islands use two distinct oceanic feeding strategies, including one putatively linked to a .sup.15N-enriched zone of the West African upwelling area. On the Eastern island of Boavista, an additional third strategy exists used by turtles feeding mostly neritically. Contrary to previous paradoxical assumptions, oceanic turtles, that represent the vast majority of the population, are not smaller than neritic turtles and therefore do not seem to feed in a suboptimal environment. Our results also suggest that the number of feeding strategies may correlate with demography, whereby a greater feeding strategy diversity matches demographic signs of recent expansion after a population bottleneck for turtles nesting on the island of Boavista. Overall, the feeding ecology of Cape Verde loggerhead turtles is complex and likely shaped by an interaction between environmental and population parameters. Our results stress the importance of conservation efforts to prevent loss of critical diversity in endangered species., Author(s): Sahmorie J. K. Cameron [sup.1] , Miguel Baltazar-Soares [sup.2] , Victor A. Stiebens [sup.1] [sup.3] , Thomas Reischig [sup.4] , Sandra M. Correia [sup.5] , Chris Harrod [sup.6] [sup.7] [...]

In 2009, Chazal et al. introduced ζ-interleavings of persistence modules. ζ-interleavings induce a pseudometric [d.sub.I] on (isomorphism classes of) persistence modules, the interleaving distance. The definitions of ζ-interleavings and [d.sub.I] generalize readily to multidimensional persistence modules. In this paper, we develop the theory of multidimensional interleavings, with a view toward applications to topological data analysis. We present four main results. First, we show that on 1-D persistence modules, [d.sub.I] is equal to the bottleneck distance [d.sub.B]. This result, which first appeared in an earlier preprint of this paper, has since appeared in several other places, and is now known as the isometry theorem. Second, we present a characterization of the ζ-interleaving relation on multidimensional persistence modules. This expresses transparently the sense in which two ζ-interleaved modules are algebraically similar. Third, using this characterization, we show that when we define our persistence modules over a prime field, [d.sub.I] satisfies a universality property. This universality result is the central result of the paper. It says that [d.sub.I] satisfies a stability property generalizing one which [d.sub.B] is known to satisfy, and that in addition, if d is any other pseudometric on multidimensional persistence modules satisfying the same stability property, then d ≤ [d.sub.I]. We also show that a variant of this universality result holds for [d.sub.B], over arbitrary fields. Finally, we show that [d.sub.I] restricts to a metric on isomorphism classes of finitely presented multidimensional persistence modules. Keywords Multidimensional persistence * Stability of persistent homology * Persistence modules * Interleavings * Algebraic stability * Isometry theorem Mathematics Subject Classification 55 * 68, 1 Introduction 1.1 Background and Motivation Persistent Homology. Persistent homology is a topological tool for studying the global, nonlinear, geometric features of data. In the last decade and a half, [...]

The effective population size (Ne) is a crucial characteristic of numerically small populations, positively correlated with their ability to persist in a changing environment and to evolve. Information about the lower bounds of Ne of natural populations is both theoretically interesting and practically important. We studied Kildin cod, an isolated population of Atlantic cod Gadus morhua from an ecologically marginal habitat (marine lake), comparing it with the parental Barents Sea population by a set of 20 microsatellite and protein loci. Overall, the genetic variability in Kildin cod was low (mean allelic richness and heterozygosity: Kildin cod 1.6, 0.26; marine cod 11.6, 0.73). We detected a single locus, the glucose-6-phosphate isomerase-1, which demonstrated a unique variation in the lake. At this locus, about 75 % of the lacustrine fishes carried an allele not found in the sea. The obtained genetic estimates of Ne of Kildin cod (less than a hundred) were much smaller than what is considered as the smallest Ne of a viable population. At the same time, Kildin cod is known to be healthy and productive. Based on the results of bottleneck tests, we hypothesize that Kildin cod has experienced founder-flush dynamics that lead to loss of genetic variation during the founder phase(s) and purging of genetic load and the rise of adaptation during flush phase(s). Electronic supplementary material The online version of this article (doi:10.1007/s00227-015-2642-8) contains supplementary material, which is available to authorized users., Author(s): Victor Andreev[sup.1] [sup.2] , Mikhail Fokin[sup.3] , Nikolai Mugue[sup.4] [sup.5] , Petr Strelkov[sup.1] Author Affiliations: (1) St. Petersburg State University, Vasil'evsky Isl., 16 line 29, 199178, St. Petersburg, Russia [...]

We study distributions of persistent homology barcodes associated to taking subsamples of a fixed size from metric measure spaces. We show that such distributions provide robust invariants of metric measure spaces and illustrate their use in hypothesis testing and providing confidence intervals for topological data analysis. Keywords Persistent homology * Stability * Robustness * Barcode space * Bottleneck metric * Gromov-Prohorov metric * Hypothesis testing * Confidence interval * Metric measure space, Mathematics Subject Classification 55U10 * 68U05 1 Introduction Topological data analysis assigns homological invariants to data presented as a finite metric space (a point cloud). If we imagine these data [...]

The paper proposes a Markovian approach to the performance evaluation of the ESSE (early slow start exit) modification of the TCP congestion control mechanism. ESSE takes advantage of estimating the optimal pipesize at the sender side to properly select initial slow start threshold. Previous simulative experiments have shown that ESSE allows one to speed-up TCP connections and significantly reduces the packet drop rate at the bottleneck. This work takes a step further in understanding the ESSE behavior by developing a model of TCP source to evaluate the influence of different settings of slow start threshold on a TCP performance. As confirmed by comparison with simulations, the model provides, significantly faster than simulations, accurate estimates of typical performance indicators such as the average completion time and average drop rate of short-lived TCP connections., 1. Introduction Recent studies (1), (2) have revealed that the majority of the Internet flows are short-lived (mice), while a smaller number of long-lived connections carry most of the Internet [...]

Although Pleistocene glacial cycles are regularly used to explain many aspects of the demographic history of coastal marine species, the present study is one of few to test a priori predictions about these effects. nucleotide sequence variation in the cytochrome b gene of the mtDNA and allele frequency variation at intron loci in the nDNA were compared between two species of Arripis (Australian Salmon) that are closely related and biologically similar other than for their allopatric distributions. The results suggest that A. truttaceus, which resides to the west of the Bass Strait, exhibits lower levels of genetic diversity and experienced a severe population bottleneck during the LGM followed by an expansion commencing some 17,000 years ago. In contrast, the population of A. trutta, which resides to the east of the Bass Strait, appears to have been largely unaffected by the LGM and has been expanding over the past 100,000 years or more. These results are consistent with a priori predictions, based on paleo-oceanographic data, that the demographic history of A. truttaceus has been more strongly affected by glacial periods by virtue of its distribution to the west of Bass Strait. Data on two other congeners are also presented to provide context for the results for A. trutta and A. truttaceus., Introduction Genetic evidence indicates that changes in the geographic range and population size of coastal marine species were common during the Pleistocene (Avise 2000; Hewitt 2000; Maggs et al. 2008). [...]

The doubly uniparental inheritance system allows for the use of two independent mitochondrial genomes for population history investigations. Under this system, two lineages of mitochondrial DNA (mtDNA) exist and males are typically heteroplasmic, having the additional, usually divergent, mitochondrial genome inherited from their male parent. This additional mtDNA typically evolves faster, potentially allowing for insight into more recent events in population history. Few studies did explore this possibility in marine mussels Mytilus showing its usefulness. Recent observations of the Mytilus trossulus mussels who have retained their native mtDNA in European waters posed the question of their origin. Are they part of a population present, but previously undetected, or is this a potentially human mediated, ongoing spread of an invasive species? To tackle this question, we amplified with species-specific primers and sequenced an approximately 1,200-bp-long fragment spanning COIII and ND2 genes from both mitochondrial genomes of mussels sampled at five locations worldwide, covering the whole M. trossulus range. The overall pattern of polymorphisms is compatible with the entirely postglacial history of the whole species, indicating a very deep bottleneck at last glacial maximum, with possible retention of the whole species in a single refugium, and the effective population size of no more than a few thousands. Both analyses of molecular variance and isolation with migration (IM) models point at the West Atlantic as the source of the European M. trossulus mussels, at least the ones who retained their native mtDNA. The hypothesis that this is an ongoing, human-mediated process was considered. To this end, comparison with the well-known case: the introduction of congeneric mussel, Mytilus galloprovincialis, from Mediterranean Sea to Asia was used. This introduction occurred within the last 100 years. The results inferred by the IM model suggest that the timing and structure of transatlantic migration of M. trossulus differs significantly from the M. galloprovincialis case: it is more than 1,000 years old and involves a much larger fraction of the ancestral population. Therefore, most likely, this invasion is not a human-mediated process., Introduction The smooth-shelled blue mussel Mytilus edulis species complex consists of three recognised, closely related and hybridising members: M. edulis, Mytilus galloprovincialis and Mytilus trossulus (McDonald et al. 1991; Gosling [...]

Several major breeding areas have been defined for the South American sea lion (Otaria flavescens) along the Atlantic Ocean including the Uruguayan and Patagonian coasts. Together with a documented and severe reduction in population sizes caused by commercial hunting in the last century, these areas show opposite population trends. While Patagonian populations are recovering since hunting ceased, Uruguayan populations are declining. In this context, population genetic structure and genetic diversity were studied for the first time with both nuclear (microsatellites) and mitochondrial (control region) markers together. Alternative scenarios were found for both markers. While mitochondrial marker showed geographically structured populations, the nuclear loci showed a lack of geographical structure. These opposite patterns in genetic structure could be explained by female phylopatry and high male dispersion. The reduction in population size caused by commercial hunting did not leave a detectable footprint of bottleneck at the genetic level., Author(s): Matías Feijoo [sup.1] , Enrique P. Lessa [sup.1] , Rocío Loizaga de Castro [sup.2] , Enrique A. Crespo [sup.2] Author Affiliations: (1) grid.11630.35, 0000000121657640, Sección Evolución, Facultad de Ciencias, [...]

The existence of three distinct populations is widely accepted for the finless porpoise (Neophocaena phocaenoides) in Chinese waters: the Yellow Sea, Yangtze River, and South China Sea populations. Here, we use nine species-specific microsatellite loci, the complete mitochondrial DNA control region (912 bp), and the complete mitochondrial cytochrome b gene (1,140 bp) to further investigate potential population stratification in the Yellow Sea using 147 finless porpoise samples from the Bohai Sea and adjacent northern Yellow Sea, two regions that were largely underrepresented in previous genetic studies. Our F-statistics analyses confirm the previously described three populations, but further demonstrate significant genetic differentiation between the [Bohai + northern Yellow] Sea and the southern Yellow Sea. On the other hand, median-joining network analyses do not exhibit well-differentiated haplotype groups among different geographic populations, suggesting the existence of shared ancestral haplotypes. Levels of microsatellite diversity are moderate to high (mean H.sub.E = 0.794) among the 147 [Bohai + northern Yellow] Sea finless porpoises and no recent bottleneck was detected, whereas mtDNA control region and cytochrome b gene diversity is low to moderate. The microsatellite genotypic and mtDNA haplotypic data also confirm the presence of mother-calf pairs in single-net bycatch cases. The results presented here highlight the necessity to treat the [Bohai + northern Yellow] Sea population (highly impacted by anthropogenic threats) as a separate Management Unit., Author(s): Xiang Li [sup.1] , Yingying Liu [sup.2] , Athanasia C. Tzika [sup.3] [sup.4] , Qian Zhu [sup.2] [sup.5] , Karine Van Doninck [sup.1] , Michel C. Milinkovitch [sup.3] Author [...]

Marine rock-pools, commonly found along the Mediterranean coasts, are isolated patches of habitat characterised by large spatial and temporal variations. The phylogeography of Calobius quadricollis and C. urbanelliae, two sibling species of moss beetles (Coleoptera, Hydraenidae) inhabiting Italian temporary marine rock-pool ecosystems, were studied using mitochondrial cytochrome c oxidase subunit I (COI). Our data suggest a strong association between the scored genetic variability and the geographical distribution of populations sampled for both species. These analyses provided evidences of episodic species range expansion and fragmentation, recurrent 'flush and crash' and bottleneck episodes probably occurring during the Glacial Cycles. The observed phylogeographical pattern is probably related to the historical and biogeographical processes of Mediterranean areas, as well as both to the ephemeral habitat tipology and limited dispersal ability of these beetles., Author(s): Gloria Antonini [sup.1] , Paolo Audisio [sup.1] , Emiliano Mancini [sup.2] , Alessio De Biase [sup.1] , Carlo Tronci [sup.3] , Giulia Rossetti [sup.1] , Marco Trizzino [sup.1] Author [...]

Variations in the relative contributions of gene flow and spatial and temporal variation in recruitment are considered the major determinants of population genetic structure in marine organisms. Such variation can be assessed through repeated measures of the genetic structure of a species over time. To test the relative importance of these two phenomena, temporal variation in genetic composition was measured in the limpet Cellana grata, among four annual cohorts over 10 years at four rocky shores in Hong Kong. A total of 408 limpets, comprising individuals from 1998, 1999, 2006 and 2007 cohorts were screened for genetic variation using five microsatellite loci. Minor but significant genetic differentiation was detected among samples from the 1998/1999 collection (F.sub.ST = 0.0023), but there was no significant differentiation among the 2006/2007 collection (F.sub.ST = 0.0008). Partitioning of genetic variation among shores was also significant in 1998/1999 but not in the 2006/2007 collection, although there was no correlation between genetic and geographic distances. There was no significant difference between collections made in 1998/1999 and 2006/2007. This lack of clear structure implies a high level of gene flow, but differentiation with time may be the result of stochastic recruitment variation among shores. Estimates of effective population size were not high (599, 95% C.L. 352-11397), suggesting the potential susceptibility of the populations to genetic drift, although a significant bottleneck effect was not detected. These findings indicate that genetic structuring between populations of C. grata in space and time may result from spatio-temporal variation in recruitment, but the potential development of biologically significant differentiation is suppressed by a lack of consistency in recruitment variability and high connectivity among shores., Author(s): Wai-Chuen Ng [sup.1] , F. C. C. Leung [sup.2] , Solomon T. C. Chak [sup.1] , G. Slingsby [sup.1] , Gray A. Williams [sup.1] Author Affiliations: (1) grid.194645.b, 0000000121742757, [...]

In this dual-task study, we applied both eross-talk logic and locus-of-slack logic to test whether participants can retrieve semantic categories in Task 2 in parallel to Task 1 bottleneck processing. Whereas cross-talk logic can detect parallel memory retrieval only in conditions of categorical overlap between tasks, the locus-of-slack approach is independent of such restrictions. As was expected, using the cross-talk logic, we found clear evidence for parallel retrieval of semantic categories when there was categorical overlap between tasks (Experiment 1). Locus-of-slack-based evidence for parallel semantic retrieval was found, however, both in conditions with (Experiment 1) and in those without (Experiment 2) categorical overlap between tasks. Crucially, however, increasing the demand for resources required to switch from Task 1 to Task 2 eliminated even the locus-of-slack-based evidence for parallel memory retrieval during the psychological refractory period (Experiment 3). Together, our results suggest that parallel retrieval is not bound to conditions of categorical overlap between tasks but, instead, is contingent upon resources needed for switching between tasks (e.g., Oriet, Tombu, & Jolicceur, 2005).

Theories of selective attention often have a central memory component, which is commonly thought to be limited in some way and is thereby a potential bottleneck in the attentional process. There have been only a few attempts to validate this assertion, and they have produced mixed results. This study presents a specific examination of the link between working memory and attention by engaging active rather than passive memory operations. Two experiments are reported that provide evidence for the involvement of working memory in the attentional blink (AB) phenomenon. Memory loads of increasing size had a detrimental effect on attentional performance within the blink-sensitive interval, but not beyond. Speeded response requirements proved to modulate the AB, but were independent from the memory load effect. Theoretical implications for current models of selective attention are discussed.

Byline: V. Y. Pan (1) Abstract: We reexamine the Wiedemann--Coppersmith--Kaltofen--Villard algorithm for randomized computation of the determinant of an integer matrix and substantially simplify and accelerate its bottleneck stage of computing the minimum generating matrix polynomial, to make the algorithm practically promising while keeping it asymptotically fast. Bibliography: 58 titles. Author Affiliation: (1) Department of Mathematics and Computer Science, Lehman College of CUNY, USA Article History: Registration Date: 10/03/2006 Received Date: 27/11/2004 Article note: Published in Zapiski Nauchnykh Seminarov POMI, Vol. 316, 2004, pp. 163--187.

Recruitment variability plays a critical role in determining local population densities of benthic organisms, but extreme vulnerability at the onset of juvenile life is a trait that is largely responsible for population survivorship trends. The aim of the present study was to determine the role of juvenile recruitment in the population structure of Necora puber. Juveniles of N. puber were collected from the lower intertidal of rocky shores of Plymouth Sound (southwest coast of the UK) and monthly size-frequency distribution were used to determine the dynamics and the growth of the population. The parameters of the von Bertalanffy growth function were estimated (K = 0.281 [year.sup.-1]; [t.sub.0] = 0.043; C = 0.103; and [t.sub.s] = 0.268) assuming a [L.sub.[infinity]] = 105 mm. Growth was markedly seasonal and present results indicated a slower juvenile growth rate than described previously for N. puber. The recruitment period was extensive and was two times higher in 2001 than in 2000 at the start of the 1 + year, but levelled off at the end of the 1 + year class on three of the four shores studied. Instantaneous mortality as high as 5.1 [year.sup.-1](99.4% [year.sup.-1]) was observed during the higher recruitment year. Early juvenile mortality appears to be density dependent and a demographic bottleneck appears to limit the number of juveniles on some shores., Introduction In marine ecosystems, recruitment variability plays a critical role in determining local population densities of benthic organisms (Caley et al. 1996) and, particularly for commercially exploited species, large fluctuations [...]

Sagitta elegans and S. setosa are the two dominant chaetognaths in the North-East (NE) Atlantic. They are closely related and have a similar ecology and life history, but differ in distributional ranges. Sagitta setosa is a typical neritic species occurring exclusively above shelf regions, whereas S. elegans is a more oceanic species with a widespread distribution. We hypothesised that neritic species, because of smaller and more fragmented populations, would have been more vulnerable to population bottlenecks resulting from range contractions during Pleistocene glaciations than oceanic species. To test this hypothesis we compared mitochondrial Cytochrome Oxidase II DNA sequences of S. elegans and S. setosa from sampling locations across the NE Atlantic. Both species displayed very high levels of genetic diversity with unique haplotypes for every sequenced individual and an approximately three times higher level of nucleotide diversity in S. elegans (0.061) compared to S. setosa (0.021). Sagitta setosa mitochondrial DNA (mtDNA) haplotypes produced a star-like phylogeny and a uni-modal mismatch distribution indicative of a bottleneck followed by population expansion. In contrast, S. elegans had a deeper mtDNA phylogeny and a multi-modal mismatch distribution as would be expected from a more stable population. Neutrality tests indicated that assumptions of the standard neutral model were violated for both species and results from the McDonald-Kreitman test suggested that selection played a role in the evolution of their mitochondrial DNA. Congruent with these results, both species had much smaller effective population sizes estimated from genetic data when compared to census population sizes estimated from abundance data, with a factor of ~[10.sup.8]-[10.sup.9] difference. Assuming that selective effects are comparable for the two species, we conclude that the difference in genetic signature can only be explained by contrasting demographic histories. Our data are consistent with the hypothesis that in the NE Atlantic, the neritic S. setosa has been more severely affected by population bottlenecks resulting from Pleistocene range shifts than the more oceanic S. elegans., Introduction Comparison of the population genetic composition of closely related species can be a powerful approach to investigate the importance of contrasting life history and ecological characteristics on a species' [...]

Sagitta elegans and S. setosa are the two dominant chaetognaths in the North-East (NE) Atlantic. They are closely related and have a similar ecology and life history, but differ in distributional ranges. Sagitta setosa is a typical neritic species occurring exclusively above shelf regions, whereas S. elegans is a more oceanic species with a widespread distribution. We hypothesised that neritic species, because of smaller and more fragmented populations, would have been more vulnerable to population bottlenecks resulting from range contractions during Pleistocene glaciations than oceanic species. To test this hypothesis we compared mitochondrial Cytochrome Oxidase II DNA sequences of S. elegans and S. setosa from sampling locations across the NE Atlantic. Both species displayed very high levels of genetic diversity with unique haplotypes for every sequenced individual and an approximately three times higher level of nucleotide diversity in S. elegans (0.061) compared to S. setosa (0.021). Sagitta setosa mitochondrial DNA (mtDNA) haplotypes produced a star-like phylogeny and a uni-modal mismatch distribution indicative of a bottleneck followed by population expansion. In contrast, S. elegans had a deeper mtDNA phylogeny and a multi-modal mismatch distribution as would be expected from a more stable population. Neutrality tests indicated that assumptions of the standard neutral model were violated for both species and results from the McDonald-Kreitman test suggested that selection played a role in the evolution of their mitochondrial DNA. Congruent with these results, both species had much smaller effective population sizes estimated from genetic data when compared to census population sizes estimated from abundance data, with a factor of ~[10.sup.8]-[10.sup.9] difference. Assuming that selective effects are comparable for the two species, we conclude that the difference in genetic signature can only be explained by contrasting demographic histories. Our data are consistent with the hypothesis that in the NE Atlantic, the neritic S. setosa has been more severely affected by population bottlenecks resulting from Pleistocene range shifts than the more oceanic S. elegans.

As processor technology continues to advance at a rapid pace, the principal performance bottleneck of shared memory systems has become the memory access latency. In order to understand the effects of cache and memory hierarchy on system latencies, performance analysts perform benchmark analysis on existing multiprocessors. In this study, we present a detailed comparison of two architectures, the HP V-Class and the SGI Origin 2000. Our goal is to compare and contrast design techniques used in these multiprocessors. We present the impact of processor design, cache/memory hierarchies and coherence protocol optimizations on the memory system performance of these multiprocessors. We also study the effect of parallelism overheads such as process creation and synchronization on the user-level performance of these multiprocessors. Our experimental methodology uses microbenchmarks as well as scientific applications to characterize the user-level performance. Our microbenchmark results show the impact of L1/L2 cache size and TLB size on uniprocessor load/store latencies, the effect of coherence protocol design/optimizations and data sharing patterns on multiprocessor memory access latencies and finally the overhead of parallelism. Our application-based evaluation shows the impact of problem size, dominant sharing patterns and number of processors used on speedup and raw execution time. Finally, we use hardware counter measurements to study the correlation of system-level performance metrics and the application's execution time performance. KEY WORDS: Parallel architectures; performance analysis; shared memory.

As processor technology continues to advance at a rapid pace, the principal performance bottleneck of shared memory systems has become the memory access latency. In order to understand the effects of cache and memory hierarchy on system latencies, performance analysts perform benchmark analysis on existing multiprocessors. In this study, we present a detailed comparison of two architectures, the HP V-Class and the SGI Origin 2000. Our goal is to compare and contrast design techniques used in these multiprocessors. We present the impact of processor design, cache/memory hierarchies and coherence protocol optimizations on the memory system performance of these multiprocessors. We also study the effect of parallelism overheads such as process creation and synchronization on the user-level performance of these multiprocessors. Our experimental methodology uses microbenchmarks as well as scientific applications to characterize the user-level performance. Our microbenchmark results show the impact of L1/L2 cache size and TLB size on uniprocessor load/store latencies, the effect of coherence protocol design/optimizations and data sharing patterns on multiprocessor memory access latencies and finally the overhead of parallelism. Our application-based evaluation shows the impact of problem size, dominant sharing patterns and number of processors used on speedup and raw execution time. Finally, we use hardware counter measurements to study the correlation of system-level performance metrics and the application's execution time performance. KEY WORDS: Parallel architectures; performance analysis; shared memory.

The depletion of shallow-water fish stocks through overexploitation has led to increasing fishing pressure on deep-sea species. Poor knowledge of the biology of commercially valuable deep-water fish has led to the serial depletion of stocks of several species across the world. Data regarding the genetic structure of deep-sea fish populations is important in determining the impact of overfishing on the overall genetic variability of species and can be used to estimate the likelihood of recolonisation of damaged populations through immigration of individuals from distant localities. Here the genetic structure of the commercially fished deep-water species the blackspot sea bream, Pagellus bogaraveo is investigated in the northeastern Atlantic using partial DNA sequencing of mitochondrial cytochrome b (cyt-b) and D-loop regions and genotyping of microsatellite loci. An absence of variation in cyt-b and low genetic variation in D-loop sequences potentially indicate that P. bogaraveo may have undergone a severe bottleneck in the past. Similar bottlenecks have been detected in other Atlantic species of fish and have possibly originated from the last glaciation. P. bogaraveo may have been particularly vulnerable to the effects of low temperature and a fall in sea level because stages of its life history occur in shallow water and coastal sites. However, there are other explanations of low genetic variability in populations of P. bogaraveo, such as a low population size and the impacts of fishing on population structure. Analysis of population structure using both D-loop and microsatellite analysis indicates low to moderate, but significant, genetic differentiation between populations at a regional level. This study supports studies on other deep-sea fish species that indicate that hydrographic or topographic barriers prevent dispersal of adults and/or larvae between populations at regional and oceanographic scales. The implications for the management and conservation of deep-sea fish populations are discussed., Introduction The depletion of fish stocks associated with the continental seas of the world has led to increasing fishing efforts directed at deep-water species (e.g. Haedrich 1995; Koslow et al. [...]

The depletion of shallow-water fish stocks through overexploitation has led to increasing fishing pressure on deep-sea species. Poor knowledge of the biology of commercially valuable deep-water fish has led to the serial depletion of stocks of several species across the world. Data regarding the genetic structure of deep-sea fish populations is important in determining the impact of overfishing on the overall genetic variability of species and can be used to estimate the likelihood of recolonisation of damaged populations through immigration of individuals from distant localities. Here the genetic structure of the commercially fished deep-water species the blackspot sea bream, Pagellus bogaraveo is investigated in the northeastern Atlantic using partial DNA sequencing of mitochondrial cytochrome b (cyt-b) and D-loop regions and genotyping of microsatellite loci. An absence of variation in cyt-b and low genetic variation in D-loop sequences potentially indicate that P. bogaraveo may have undergone a severe bottleneck in the past. Similar bottlenecks have been detected in other Atlantic species of fish and have possibly originated from the last glaciation. P. bogaraveo may have been particularly vulnerable to the effects of low temperature and a fall in sea level because stages of its life history occur in shallow water and coastal sites. However, there are other explanations of low genetic variability in populations of P. bogaraveo, such as a low population size and the impacts of fishing on population structure. Analysis of population structure using both D-loop and microsatellite analysis indicates low to moderate, but significant, genetic differentiation between populations at a regional level. This study supports studies on other deep-sea fish species that indicate that hydrographic or topographic barriers prevent dispersal of adults and/or larvae between populations at regional and oceanographic scales. The implications for the management and conservation of deep-sea fish populations are discussed.

This article reviews the recent developments in the functional chain from climate models to climate scenarios, through hydrology all the way to water resources management, design and policy making. Although climate models, such as Global Circulation Models (GCMs) continue to evolve, their outputs remain crude and often even inappropriate to watershed-scale hydrological analyses. The bridging techniques are evolving, though. Many families of regionalization technologies are under progress in parallel. Perhaps the most important advances are in the field of regional weather patterns, such as ENSO (El Nino-Southern Oscillation), NAO (North Atlantic Oscillation) and many more. The gap from hydrology to water resources development is by far not that wide. The traditional and contemporary practices are well in place. In climate change studies, the bottleneck is not in this link itself but in the climatic input. The tendency seems to be towards integrated water resources assessments, where climate is only one among many changes that are expected to occur, such as demography, land cover and land use, economy, technologies, and so forth. In such a pragmatic setting a risk-analytic interpretation of those scenarios is often called for. The above-outlined continuum from climate to water is a topic where the physically based modelers, the empiricists and the pragmatists should not get restricted to their own way of thinking. The issues should develop hand in hand. Perhaps the greatest challenge is to incorporate and respect the pragmatic policy-related component to the two other branches. For this purpose, it is helpful to reverse the direction of thinking from time to time to start--instead of climate models--from practical needs and think how the climate scenarios and models help really in the difficult task of designing better water structures, outline better policies and formulate better operational rules in the water field.

Communication latencies within critical sections constitute a major bottleneck in some classes of emerging parallel workloads. In this paper, we argue for the use of two mechanisms to reduce these communication latencies: Inferentially Queued locks (IQLs) and Speculative Push (SP). With IQLs, the processor infers the existence, and limits, of a critical section from the use of synchronization instructions and joins a queue of lock requestors, reducing synchronization delay. The SP mechanism extracts information about program structure by observing IQLs. SP allows the cache controller, responding to a request for a cache line that likely includes a lock variable, to predict the data sets the requestor will modify within the associated critical section. The controller then pushes these lines from its own cache to the target cache, as well as writing them to memory. Overlapping the protected data transfer with that of the lock can substantially reduce the communication latencies within critical sections. By pushing data in exclusive state, the mechanism can collapse a read-modify-write sequences within a critical section into a single local cache access. The write-back to memory allows the receiving cache to ignore the push. Neither mechanism requires any programmer or compiler support nor any instruction set changes. Our experiments demonstrate that IQLs and SP can improve performance of applications employing frequent synchronization. KEY WORDS: Synchronization; data forwarding; inferential queueing; critical sections; migratory sharing.

Communication latencies within critical sections constitute a major bottleneck in some classes of emerging parallel workloads. In this paper, we argue for the use of two mechanisms to reduce these communication latencies: Inferentially Queued locks (IQLs) and Speculative Push (SP). With IQLs, the processor infers the existence, and limits, of a critical section from the use of synchronization instructions and joins a queue of lock requestors, reducing synchronization delay. The SP mechanism extracts information about program structure by observing IQLs. SP allows the cache controller, responding to a request for a cache line that likely includes a lock variable, to predict the data sets the requestor will modify within the associated critical section. The controller then pushes these lines from its own cache to the target cache, as well as writing them to memory. Overlapping the protected data transfer with that of the lock can substantially reduce the communication latencies within critical sections. By pushing data in exclusive state, the mechanism can collapse a read-modify-write sequences within a critical section into a single local cache access. The write-back to memory allows the receiving cache to ignore the push. Neither mechanism requires any programmer or compiler support nor any instruction set changes. Our experiments demonstrate that IQLs and SP can improve performance of applications employing frequent synchronization. KEY WORDS: Synchronization; data forwarding; inferential queueing; critical sections; migratory sharing.

Survival and growth of early post-settlement stages are critical for the development of seaweed populations. Fucoid germlings commonly settle in dense monospecific aggregates, where intraspecific competition and environmental variables (e.g. nutrient concentration and temperature) may affect survival and growth. Using factorial experiments, we determined the effects of settlement density (~10, ~50 and ~250 germlings [cm.sup.-2]), nutrient enrichment (from ~10 to ~40 [micro]M N and from ~0.5 to ~2.5 [micro]M P), and temperature (7[degrees]C and 17[degrees]C) on Fucus serratus and F. evanescens germlings in laboratory cultures over 3 months. Settlement density, nutrient concentration and temperature interactively affected growth of germlings, and the magnitude of this interaction varied between the two species. This represents the first record of such factorial interactions in Fucus spp. germlings. Intraspecific competition, estimated as the relative reduction in germling growth and survival from low to high densities, increased with decreasing nutrient concentration and increasing temperature in both species. While temperature and nutrient concentration had little effect on germling size distributions, size inequality and skewness generally increased with germling density, indicating that a few large individuals gained dominance and suppressed many smaller ones at high density. Self-thinning increased with settlement density and depended on nutrient concentration and species at high density. At high density, self-thinning increased with decreasing nutrient levels in F. evanescens, but not in F. serratus. At low density, nutrient enrichment increased germling growth in F. evanescens, but not in F. serratus, whereas growth in both species was stimulated by nutrient enrichment at higher densities. These results suggest that germling growth and self-thinning are more sensitive to variation in nutrient concentration in F. evanescens than in F. serratus. The potential implications of our findings for the understanding of eutrophication-related abundance changes in both species in southern Norway are discussed., Introduction Early stages of substrate colonisation usually represent a bottleneck in the development of seaweed populations, as germlings are generally more susceptible to physical and biological stresses than adults (Brawley [...]

The present study compared population genetic structure of two northern hemisphere polychaetes, Neanthes virens (Sars, 1835) and Hediste diversicolor (O.F. Muller, 1776), with different life-history traits. N. virens has a pelagic larval phase that may last as long as 9 days, while H. diversicolor broods its offspring. It was predicted that N. virens populations, especially over relatively short geographic distances, would be more genetically similar than H. diversicolor populations. Sequence data were obtained for two mitochondrial genes, cytochrome c oxidase I (COI) and cytochrome b (cyt b). The COI gene showed no variation in 16 N. vitens individuals from 12 locations, and it was not examined in H. diversicolor. The nucleotide sequence of the cyt b gene was examined in 93 N. virens individuals collected in 1992, 1999, and 2000 from 12 localities throughout its range (North America, Europe, Japan) and from 33 H. diversicolor individuals collected in 1999 and 2001 from one locality in eastern Canada and two localities in France (Roscoff and Marseille). In N. virens, one cyt b haplotype was shared by 89% (83 out of 93) and only two other haplotypes were found. Significant population structure was observed in H. diversicolor. In the 33 sequences compared, 18.9% of sites were polymorphic and 12 haplotypes were identified. There were two haplotypes in the Canadian population, three in the Marseille samples, and seven in the Roscoff samples, and no haplotype was found in common between any two sites. These results show that widely separated H. diversicolor populations are strongly differentiated at the cyt b locus. The most plausible interpretation for the low variation at the COI and cyt b loci in N. virens, and for the lack of variation at allozyme loci (based on an initial survey of a smaller subset of populations), is that this species has experienced a drastic bottleneck and that a few remaining lineages recolonized its entire range.

The author examines telecommunications, electric utilities, and airlines, finding both deregulation benefits and the need for government to continue involvement after deregulation. Benefits of deregulation include economic efficiency, bottleneck regulation, and antitrust policy enforcement.

Byline: Samuel H. Huang (1), Xing Hao (1), Michael Benjamin (2) Keywords: Knowledge acquisition; neural networks; fuzzy logic; knowledge-based engineering Abstract: In order to remain competitive in the global market, original equipment manufacturers (OEMs) are developing a process-based, knowledge-driven product development environment with emphasis on the acquisition, storing, and utilization of manufacturing knowledge. This is usually achieved by using the symbolic artificial intelligence (AI) approach. Specifically, knowledge-based expert systems are developed to capture human expertise, mostly in terms of IF--THEN production rules. It has been recognized that the development of symbolic knowledge-based expert systems suffers from the so-called knowledge acquisition bottleneck. Knowledge acquisition is the process of collecting domain knowledge and transforming the knowledge into a computerized representation. It is a challenging and time-consuming process due to the difficulties involved in eliciting knowledge from human experts. This paper presents an automated approach for knowledge acquisition by integrating neural networks' learning ability and fuzzy logic's structured knowledge representation. Using this approach, knowledge is automatically acquired from data and represented using humanly intelligible fuzzy rules. The approach is applied to a case study of the design and manufacturing of micromachined atomizers for gas turbine engine. The influence of geometric features on the performance of the atomizers is investigated. The results are then compared with those obtained using traditional regression analysis approach (abstract mathematical models). It was found that the automated approach provides an efficient means for knowledge acquisition. Since the fuzzy rules extracted are easy to understand, they can be used to allow more clear specification of manufacturing processes and to shorten learning curves for novice manufacturing engineers. Author Affiliation: (1) Intelligent CAM Systems Laboratory, Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, cToledo, OH, 43606 (2) Gas Turbine Fuel Systems Division, Parker Hannifin Corporation, 9200 Tyler Boulevard, Mentor, OH, 44060 Article History: Registration Date: 17/10/2004

Byline: Yukou Mochida (1), Toshitaka Tsuda (1), Hideo Kuwahara (1) Keywords: photonic network; next-generation network; routing; label switching; virtual router view network; edge node; node cut-through; WDM transport; wavelength channel; optical add/drop; optical cross-connect; wavelength routing; AOTF; tunable LD Abstract: This paper describes the possible impact of photonic technologies on the next-generation network. With the explosion of the Internet (IP), the capacity demand is increasing exponentially, which exceeds Moor's law. The next-generation IP network should sustain this increase. This paper shows the possible node processing bottleneck even the transmission capacity can be supported by the use of WDM technology. Based on this analysis, the paper proposes a virtual router network as a solution, which applies a logical full-mesh connection based on salient features of photonic network technology. Development of the WDM technology sets the target at 1000 wavelengths on a fiber so that a dynamic wavelength routing function is becoming available. The increase in wavelengths, transparency among wavelengths, and the wavelength routing function can provide an optical path, which forms the base of a logical full-mesh structure and also provides an easy migration scenario from the current network to the next-generation IP network. The possibility is examined by calculation using a bi-directionalloop network as an example. As the foundation of the proposal, the current statusof photonic network technologies is described with future projection. Author Affiliation: (1) Network Systems Laboratories, Fujitsu Laboratories Ltd., Kamikodanaka 4-1-1, Nakahara-Ku, Kawasaki, 211-8588, Japan Article History: Registration Date: 04/10/2004

We describe three highly polymorphic microsatellite loci which have been isolated from the giant tiger prawn Penaeus monodon. The number of alleles present among 312 samples at the loci Pmo9, Pmo25 and Pmo27 were 84, 34 and 35, respectively, with heterozygosities all >90%. Analyses of the distribution of length variation at three microsatellite loci among five Australian P. monodon populations revealed strong differentiation between populations from the west and those from the northern and eastern coasts. Tests for population differentiation ([F.sub.ST]) values and an analogous measure for microsatellite loci ([R.sub.ST]) all demonstrated that Western Australian P. monodon are a separate genetic stock which exhibits reduced genetic variation relative to the other populations. Reduced variability is consistent with a recent population bottleneck or colonization by a small founding population from the east when sea links between Indonesia, New Guinea and Australia were re-established following the last ice age. The results of this study are in agreement with previous surveys of P. monodon conducted with allozymes and mtDNA.

The genetic relationships among South-East Asian populations of the scad mackerels Decapterus macarellus, D. macrosoma and D. russelli (Pisces: Carangidae) were investigated. In 1995 and 1996, 216 fish were sampled in seven localities spanning the seas of Indonesia and were examined for restriction-site polymorphisms using ten restriction enzymes for the mitochondrial (mt) DNA control region, amplified by the polymerase chain-reaction. The inferred phylogeny of haplotypes led to the recognition of three distinct mitochondrial lineages or phylads consistent with the distinctions of current taxonomy. All 15 mtDNA haplotypes found in D. macarellus and all 9 haplotypes found in D. macrosoma were arranged as star-like clusters, suggesting recent evolutionary history. In contrast, the phylad formed by 6 haplotypes in D. russelli from the Sulawesi Sea exhibited diffuse topology, suggesting that ancestral lineages of this species have been retained to the present. Average nucleotide-divergence estimates between haplotypes of different phylads were between 0.042 and 0.135, suggesting ancient separation, in consistency with published allozyme data. High levels of haplotype diversity, but no geographical heterogeneity, was detected within D. macarellus from the Molucca Sea and the Banda Sea. Populations of D. macrosoma exhibited both significant differences between adjacent regions (Sunda Strait and Java Sea), and broadscale genetic homogeneity from the South China Sea to the Sulawesi Sea via the Java Sea and Makassar Strait. The geographic isolation of the D. macrosoma population sampled in the Sunda Strait suggests that this region constitute a sharp transition zone between the Indian Ocean and the Sunda Shelf. Near-monomorphism of haplotypes and low nucleotide diversity ([d.sub.x]) were observed in the samples of D. macrosoma from the continental shelf (haplotype-diversity estimates, h, = 0.00 to 0.25 [+ or -] 0.08 and [d.sub.x] = 0.000 to 0.002). This was in contrast to the comparatively high haplotype and nucleotide diversities observed in other pelagic fish species including D. macarellus (h = 0.82 [+ or -] 0.05, [d.sub.x] = 0.012 to 0.015) and D. russelli (h = 0.63 [+ or -] 0.12, [d.sub.x] = 0.016), and in the oceanic D. macrosoma population sampled in the Sunda Strait (h = 0.67 [+ or -] 0.31, [d.sub.x] = 0.005). We hypothesise that this may be the consequence of recent and perhaps repeated bottleneck events that have affected the D. macrosoma population sampled on the continental shelf.