Home About us Contact
|
Home About us Contact | ||
|
|
||
Explosive Growth (explosive + growth)
Selected AbstractsClustering revealed in high-resolution simulations and visualization of multi-resolution features in fluid,particle modelsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 2 2003Krzysztof Boryczko Abstract Simulating natural phenomena at greater accuracy results in an explosive growth of data. Large-scale simulations with particles currently involve ensembles consisting of between 106 and 109 particles, which cover 105,106 time steps. Thus, the data files produced in a single run can reach from tens of gigabytes to hundreds of terabytes. This data bank allows one to reconstruct the spatio-temporal evolution of both the particle system as a whole and each particle separately. Realistically, for one to look at a large data set at full resolution at all times is not possible and, in fact, not necessary. We have developed an agglomerative clustering technique, based on the concept of a mutual nearest neighbor (MNN). This procedure can be easily adapted for efficient visualization of extremely large data sets from simulations with particles at various resolution levels. We present the parallel algorithm for MNN clustering and its timings on the IBM SP and SGI/Origin 3800 multiprocessor systems for up to 16 million fluid particles. The high efficiency obtained is mainly due to the similarity in the algorithmic structure of MNN clustering and particle methods. We show various examples drawn from MNN applications in visualization and analysis of the order of a few hundred gigabytes of data from discrete particle simulations, using dissipative particle dynamics and fluid particle models. Because data clustering is the first step in this concept extraction procedure, we may employ this clustering procedure to many other fields such as data mining, earthquake events and stellar populations in nebula clusters. Copyright © 2003 John Wiley & Sons, Ltd. [source] The Temporary Staffing Industry: Growth Imperatives and Limits to Contingency,ECONOMIC GEOGRAPHY, Issue 4 2002Nik Theodore Abstract: The temporary staffing industry (TSI) in the United States has enjoyed explosive growth since the 1970s, during which time the market for temporary labor has become increasingly complex and diverse. Rather than focus, as has typically been done, on the wider labor market effects of this sustained expansion in temporary employment, this article explores patterns and processes of industrial restructuring in the TSI itself. The analysis reveals a powerfully recursive relationship among evolving TSI business practices, the industry's strategies for building and extending the market, and urban labor market outcomes as the sector has grown through a series of qualitatively differentiated phases of development or "modes of growth." Moreover, the distinctive character of the TSI's geographic rollout raises a new set of questions concerning, inter alia, the links between temping and labor market deregulation, the nature of local competition, the scope for and limits of value-adding strategies, and the emerging global structure of the temp market. This idiosyncratic industry,which has been a conspicuous beneficiary of growing economic instability,has, throughout the past three decades, restructured continuously through a period of sustained but highly uneven growth. In so doing, it has proved to be remarkably inventive in extending the market for contingent labor, but has encountered a series of (possibly structural) obstacles to further expansion in its domestic market. These obstacles, in turn, have triggered an unprecedented phase of international integration in the TSI, along with a new mode of development,global growth. [source] Cranial fasciitis of childhoodINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2003Margarita Larralde MD A 2-month-old boy was seen at our pediatric dermatology department with a history of a tumoral lesion of the scalp since his birth. On examination he had a single, ovoid, firm, 2 × 1.8-cm painless subcutaneous mass on the temporal left calvarium, covered by normal skin (Fig. 1). It had experienced explosive growth in the preceding 2 weeks. There was no history of previous trauma in the area. The remainder of the examination was normal. Roentgenographic studies of the skull revealed a soft-tissue mass without involvement of the underlying bone. Ultrasonography of the lesion showed it to be an echolucid tumor. With the presumed diagnosis of dermoid cyst we sent the patient for surgical removal. At surgery, the lesion did not have the typical surgical appearance of a cyst. The histopathologic exam of the specimen was interpreted as cranial fasciitis of childhood (Fig. 2). Immunohistochemistry showed diffuse positivity for vimentin and muscle actin. After 1 year the patient is free of lesions. Figure 1. Lesion at the temporal left calvarium Figure 2. Proliferation of loosely arranged spindle cells in a loose myxoid stroma (H&E stain, × 40) [source] A distributed networking system for multimedia Internet access service using ATM over ADSLINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2004Daniel Won-Kyu Hong This paper proposes a distributed networking system architecture for Internet-access service provision using ATM over xDSL technology. We describe the hierarchical network model in deploying ADSL services across the ATM access networks, which can easily accommodate the explosive growth of ADSL subscribers in the future. In addition, this paper describes the distributed networking system and its capability to provide a systemic network management using the principal networking concepts of service ordering, addressing, routing, adaptation and switching. All of the networking system components with CORBA objects in favor of the distribution and location transparency are defined and described using the CORBA interface description language (IDL) for commonality. Lastly, we present its implementation and operation in Korea Telecom.,Copyright © 2004 John Wiley & Sons, Ltd. [source] Asymmetric Synthesis with Silicon-Based Bulky Amino OrganocatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Li-Wen Xu Abstract Recent years have witnessed an explosive growth in the field of amino organocatalysis, especially in asymmetric enamine and iminium catalysis. Except for the obvious interaction between organocatalyst and substrate, the impact of bulky side group ons stereoselectivity is not as simple as one could imagine. Within the development of bulky site-stereoselective organocatalysts, functional silyl organocatalysts with a bulky silicon group are promising and meet the high standards of modern synthetic methods. This review focuses on the recent advances in the synthetic applications of silicon-based, bulky amino organocatalysts in which catalysts containing an organosilicon moiety or group play a formative role in controlling both the course of the reaction as well as the stereoselectivity. [source] Twenty years of phylogeography: the state of the field and the challenges for the Southern HemisphereMOLECULAR ECOLOGY, Issue 17 2008LUCIANO B. BEHEREGARAY Abstract Phylogeography is a young, vigorous and integrative field of study that uses genetic data to understand the history of populations. This field has recently expanded into many areas of biology and also into several historical disciplines of Earth sciences. In this review, I present a numerical synthesis of the phylogeography literature based on an examination of over 3000 articles published during the first 20 years of the field (i.e. from 1987 to 2006). Information from several topics needed to evaluate the progress, tendencies and deficiencies of the field is summarized for 10 major groups of organisms and at a global scale. The topics include the geography of phylogeographic surveys, comparative nature of studies, temporal scales and major environments investigated, and genetic markers used. I also identify disparities in research productivity between the developing and the developed world, and propose ways to reduce some of the challenges faced by phylogeographers from less affluent countries. Phylogeography has experienced explosive growth in recent years fuelled by developments in DNA technology, theory and statistical analysis. I argue that the intellectual maturation of the field will eventually depend not only on these recent developments, but also on syntheses of comparative information across different regions of the globe. For this to become a reality, many empirical phylogeographic surveys in regions of the Southern Hemisphere (and in developing countries of the Northern Hemisphere) are needed. I expect the information and views presented here will assist in promoting international collaborative work in phylogeography and in guiding research efforts at both regional and global levels. [source] Stromal cells of fibrodysplasia ossificans progressiva lesions express smooth muscle lineage markers and the osteogenic transcription factor Runx2/Cbfa-1: clues to a vascular origin of heterotopic ossification?THE JOURNAL OF PATHOLOGY, Issue 1 2003Laszlo Hegyi Abstract Fibrodysplasia ossificans progressiva (FOP) is a rare heritable genetic disorder, which is characterized pathologically by sporadic episodes of explosive growth of mesenchymal cells in skeletal muscle followed by cellular differentiation to heterotopic bone through an endochondral process. This study examined the histological origin and differentiation state of stromal cells in early FOP lesions and investigated the association between the phenotype of these FOP cells and bone formation. Interestingly, FOP lesional stromal cells were found to display characteristics of the smooth muscle (SM) cell lineage and are therefore potentially of vascular origin. These cells co-express multiple SM lineage markers along with multiple proteins associated with bone formation including the obligate osteogenic transcription factor Runx2/Cbfa-1. It is hypothesized that the stromal cells of early FOP lesions may be locally recruited vascular cells or cells of the bone marrow stroma and that these cells maintain the potential (given the correct environmental stimuli) to differentiate along an endochondral ossification pathway. Copyright © 2003 John Wiley & Sons, Ltd. [source] Thermodynamic analysis of snowball Earth hysteresis experiment: Efficiency, entropy production and irreversibilityTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 646 2010Valerio Lucarini Abstract We present an extensive thermodynamic analysis of a hysteresis experiment performed on a simplified yet Earth-like climate model. We slowly vary the solar constant by 20% around the present value and detect that for a large range of values of the solar constant the realization of snowball or of regular climate conditions depends on the history of the system. Using recent results on the global climate thermodynamics, we show that the two regimes feature radically different properties. The efficiency of the climate machine monotonically increases with decreasing solar constant in present climate conditions, whereas the opposite takes place in snowball conditions. Instead, entropy production is monotonically increasing with the solar constant in both branches of climate conditions, and its value is about four times larger in the warm branch than in the corresponding cold state. Finally, the degree of irreversibility of the system, measured as the fraction of excess entropy production due to irreversible heat transport processes, is much higher in the warm climate conditions, with an explosive growth in the upper range of the considered values of solar constants. Whereas in the cold climate regime a dominating role is played by changes in the meridional albedo contrast, in the warm climate regime changes in the intensity of latent heat fluxes are crucial for determining the observed properties. This substantiates the importance of addressing correctly the variations of the hydrological cycle in a changing climate. An interpretation of the climate transitions at the tipping points based upon macro-scale thermodynamic properties is also proposed. Our results support the adoption of a new generation of diagnostic tools based on the second law of thermodynamics for auditing climate models and outline a set of parametrizations to be used in conceptual and intermediate-complexity models or for the reconstruction of the past climate conditions. Copyright © 2010 Royal Meteorological Society [source] Modelling strategic use of the national antiviral stockpile during the CONTAIN and SUSTAIN phases of an Australian pandemic influenza responseAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 2 2010Jodie McVernon Abstract Objective: To define optimum use of the national antiviral stockpile during the early phases of the response to pandemic influenza in Australia, to inform the 2008 revision of the Australian Health Management Plan for Pandemic Influenza. Methods: A mathematical model was used to compare strategic uses of antiviral agents for treatment and post-exposure prophylaxis to limit transmission until availability of a strain-specific vaccine. The impact of provision of pre-exposure prophylaxis to healthcare workers (HCWs) on the ability to control the epidemic was also assessed. Results: Optimal constraint of epidemic growth was achieved by intensive ascertainment of contacts of cases for post-exposure prophylaxis for as long as feasible. While pre-exposure prophylaxis of healthcare workers utilised a substantial proportion of the stockpile, this did not impede disease control or the ability to treat cases. Absolute delays to outbreak depended on both the intervention strategy and the growth rate of the epidemic. As vaccination was only effective when introduced before explosive growth, this timing was critical to success. Conclusions and implications: Liberal distribution of antiviral drugs to limit disease spread for as long as is feasible represents optimal use of these agents to constrain epidemic growth. In reality, additional non-pharmaceutical control measures are likely to be required to control transmission until vaccines can definitively contain pandemic influenza outbreaks. [source] A scheme for authentication and dynamic key exchange in wireless networksBELL LABS TECHNICAL JOURNAL, Issue 2 2002Uri Blumenthal Despite significant shortcomings in the initial security architecture, 802.11 wireless LANs have experienced explosive growth in recent years. Ongoing work in IEEE standards bodies is currently attempting to fix these shortcomings. One specific topic that has received extensive attention is how to enable these networks to authenticate users and to dynamically establish per-user per-session cryptographic keys. The IEEE 802.1x Port-Based Access Control standard, which formalizes a new EAP-over-LAN (EAPOL) protocol, has emerged as the preferred way to achieve this. The EAPOL protocol employs the extensible authentication protocol (EAP), standardized by the Internet Engineering Task Force, to allow the use of existing and new authentication methods and authentication, authorization, and accounting (AAA) infrastructure. In this paper we present a new EAP scheme,called shared key exchange (SKE),suitable for use in 802.11 private or public access wireless LANs. The scheme relies on secure pre-shared secret keys in wireless LAN mobile nodes devices and AAA servers. When instantiated with relatively minor changes to RADIUS and EAP,the resulting protocol is provably secure and offers a full set of security features. A second, simplified protocol results from minimal modifications to existing RADIUS and EAP standards, but it provides a lower level of security. Both protocols efficiently support roaming scenarios wherein an end user roams across different networks and requires frequent re-authentication with low latency. The protocols can easily be extended to support migration to new AAA protocols such as DIAMETER. © 2002 Lucent Technologies Inc. [source] Isotopic ecology ten years after a call for more laboratory experimentsBIOLOGICAL REVIEWS, Issue 1 2009Carlos Martínez del Rio Abstract About 10 years ago, reviews of the use of stable isotopes in animal ecology predicted explosive growth in this field and called for laboratory experiments to provide a mechanistic foundation to this growth. They identified four major areas of inquiry: (1) the dynamics of isotopic incorporation, (2) mixing models, (3) the problem of routing, and (4) trophic discrimination factors. Because these areas remain central to isotopic ecology, we use them as organising foci to review the experimental results that isotopic ecologists have collected in the intervening 10 years since the call for laboratory experiments. We also review the models that have been built to explain and organise experimental results in these areas. [source] A phylogenetic supertree of the bats (Mammalia: Chiroptera)BIOLOGICAL REVIEWS, Issue 2 2002KATE E. JONES ABSTRACT We present the first estimate of the phylogenetic relationships among all 916 extant and nine recently extinct species of bats (Mammalia: Chiroptera), a group that accounts for almost one-quarter of extant mammalian diversity. This phylogeny was derived by combining 105 estimates of bat phylogenetic relationships published since 1970 using the supertree construction technique of Matrix Representation with Parsimony (MRP). Despite the explosive growth in the number of phylogenetic studies of bats since 1990, phylogenetic relationships in the order have been studied non-randomly. For example, over one-third of all bat systematic studies to date have focused on relationships within Phyllostomidae, whereas relationships within clades such as Kerivoulinae and Murinae have never been studied using cladistic methods. Resolution in the supertree similarly differs among clades: overall resolution is poor (46.4% of a fully bifurcating solution) but reaches 100% in some groups (e.g. relationships within Mormoopidae). The supertree analysis does not support a recent proposal that Microchiroptera is paraphyletic with respect to Megachiroptera, as the majority of source topologies support microbat monophyly. Although it is not a substitute for comprehensive phylogenetic analyses of primary molecular and morphological data, the bat supertree provides a useful tool for future phylogenetic comparative and macroevolutionary studies. Additionally, it identifies clades that have been little studied, highlights groups within which relationships are controversial, and like all phylogenetic studies, provides preliminary hypotheses that can form starting points for future phylogenetic studies of bats. [source] Recent Advances in Asymmetric Gold CatalysisCHEMCATCHEM, Issue 6 2010Sujata Sengupta Au revoir: Recent years have seen explosive growth in the use of homogeneous gold catalysts, owing to their excellent chemoselectivity, high efficiency, and applicability under mild conditions. In this Minireview, recent progress regarding asymmetric gold catalysis is summarized with discussion focused on homogeneous Au catalysts promoting CC multiple bond activation toward the synthesis of enantiomerically enriched products. [source] | |||||||||||||||||||