3,072 research outputs found

    Extinction transitions in correlated external noise

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    We analyze the influence of long-range correlated (colored) external noise on extinction phase transitions in growth and spreading processes. Uncorrelated environmental noise (i.e., temporal disorder) was recently shown to give rise to an unusual infinite-noise critical point [Europhys. Lett. 112, 30002 (2015)]. It is characterized by enormous density fluctuations that increase without limit at criticality. As a result, a typical population decays much faster than the ensemble average which is dominated by rare events. Using the logistic evolution equation as an example, we show here that positively correlated (red) environmental noise further enhances these effects. This means, the correlations accelerate the decay of a typical population but slow down the decay of the ensemble average. Moreover, the mean time to extinction of a population in the active, surviving phase grows slower than a power law with population size. To determine the complete critical behavior of the extinction transition, we establish a relation to fractional random walks, and we perform extensive Monte-Carlo simulations.Comment: 11 pages, 12 figures, Final versio

    Two Suites for Solo Instruments

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    TWO SUITES FOR SOLO INSTRUMENTS: MA Thesis Matthew O. Thomas, Composer This Thesis contains two Suites for Solo Instruments: Suite Médiévale for guitar and Seven Recital Studies for Intermediate Grade for piano solo. The recital studies were conceived as a way to fill a void in music literature for beginning advanced pianists; those students not quite ready for the large works of the masters, but are seeking challenging repertoire beyond the formulaic lesson and recital books. Each of the seven is an example of a different style, form, or theoretical concept. Notes for the performer have been included with recommendations for further study or listening. Suite Médiévale is a four movement work for solo guitar based generally on medieval dance forms; Lament, Base Dance, Pavane, and Trotto. The suite wavers between introspection and frantic dancing, lyric singing and rhythmic gyration, lament and celebration

    Some Thoughts on the Meaning and Scope of the Montana Constitution\u27s Dignity Clause with Possible Applications

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    Some Thoughts on the Meaning and Scope of the Montana Constitution\u27s Dignity Claus

    Efficiency and Voluntary Implementation in Markets with Repeated Pairwise Bargaining

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    We examine a simple bargaining setting, where heterogeneous buyers and sellers are repeatedly matched with each other. We begin by characterizing efficiency in such a dynamic setting, and discuss how it differs from efficiency in a centralized static setting. We then study the allocations which can result in equilibrium when the matched buyers and sellers bargain through some extensive game form. We take an implementation approach, characterizing the possible allocation rules which result as the extensive game form is varied. We are particularly concerned with the impact of making trade voluntary: imposing individual rationality {\sl on and off} the equilibrium path. No buyer or seller consumates an agreement which leaves them worse off than the discounted expected value of their future rematching in the market. Finally, we compare and contrast the efficient allocations with those that could ever arise as the equlibria of some voluntary negotiation procedure.implementation, bargaining, matching, search, individual rationality

    Networks and the epidemiology of infectious disease

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    The science of networks has revolutionised research into the dynamics of interacting elements. It could be argued that epidemiology in particular has embraced the potential of network theory more than any other discipline. Here we review the growing body of research concerning the spread of infectious diseases on networks, focusing on the interplay between network theory and epidemiology. The review is split into four main sections, which examine: the types of network relevant to epidemiology; the multitude of ways these networks can be characterised; the statistical methods that can be applied to infer the epidemiological parameters on a realised network; and finally simulation and analytical methods to determine epidemic dynamics on a given network. Given the breadth of areas covered and the ever-expanding number of publications, a comprehensive review of all work is impossible. Instead, we provide a personalised overview into the areas of network epidemiology that have seen the greatest progress in recent years or have the greatest potential to provide novel insights. As such, considerable importance is placed on analytical approaches and statistical methods which are both rapidly expanding fields. Throughout this review we restrict our attention to epidemiological issues

    Extinction Transitions in Correlated External Noise

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    We analyze the influence of long-range correlated (colored) external noise on extinction phase transitions in growth and spreading processes. Uncorrelated environmental noise (i.e., temporal disorder) was recently shown to give rise to an unusual infinite-noise critical point [Europhys. Lett. 112, 30002 (2015)EULEEJ0295-507510.1209/0295-5075/112/30002]. It is characterized by enormous density fluctuations that increase without limit at criticality. As a result, a typical population decays much faster than the ensemble average, which is dominated by rare events. Using the logistic evolution equation as an example, we show here that positively correlated (red) environmental noise further enhances these effects. This means, the correlations accelerate the decay of a typical population but slow down the decay of the ensemble average. Moreover, the mean time to extinction of a population in the active, surviving phase grows slower than a power law with population size. To determine the complete critical behavior of the extinction transition, we establish a relation to fractional random walks, and we perform extensive Monte Carlo simulations

    Stakeholder Perceptions of Drupal Project Success

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    The purpose of this research was to collect descriptive data about Drupal projects and explore the relationships between various factors and perceived project success. Literature was examined to explore a variety of perspectives on project success. From this literature, a survey was developed. This survey was administered to a sample of Drupal project stakeholders. It collected information about Drupal expertise and experience level, asked respondents to consider their most recent Drupal project and answer questions about it, and asked respondents to rate characteristics of projects in terms of their association with project success and failure. The survey also collected qualitative data about stakeholder perceptions of project success. Results and implications of the research are discussed and suggestions for future research are presented

    Lithostratigraphy and Sequence Stratigraphy of Ultra-Deep E-Field, Eastern Niger Delta: Reservoir, Geological and Biostratigraphical Evidence

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    The ultra-deep offshore, eastern Niger Delta is marked by rapid, cyclic deposition of thick units of siliciclastic sediments ranging from deep marine to non-marine environments, deposited into rapidly subsiding sub-basins occurring along the slope of the continental margin. This rapid deposition resulted in thick third-order sequences and systems tracts. Patterns of deposition were analysed from seismic reflection configuration and well-log patterns. Lithofacies patterns critical for systems tract recognition were interpreted from well logs and tied to seismic sections where possible. Sediment accumulation plots were constructed and employed to interpret the location of stratigraphic condensation, key surfaces, diffuse boundaries between systems tracts and evaluate the significance of condensed sections. The origin of these condensed sections is caused by major allocyclic changes associated with transgression and shifting of the deltaic depocenter that fed the area. The regional change in condensation through time was interpreted as reflecting avulsion of the shallow marine sediment source. The compilation of sediment accumulation plots also showed a major increase in sedimentation approximately 2.4 Ma; caused by the influx of the prograding shallow marine sediments. Wells located in distal regions in this field are more condensed [steeper slope] than proximal locations. The resulting analyses of this study showed that the basin-floor fan has the highest rate of deposition and could be identified as a gentle slope in the line of sediment accumulation. In the distal regions of the field, TST’s are characterized by sediment starvation because most of the sediments are trapped in the proximal areas. The maximum flooding surfaces [MFS’s] were recorded in deep water as condensed sections.  Secondary condensed sections were delineated and interpreted to have deposited above the top basin-floor fan surface [tbfs] and top slope fan surface [tsfs]. In addition to traditional first downhole occurrence biostratigraphy, the database also contains information on nannofossil abundance. The sands encountered in the reservoirs are correlatable indicating a relatively longer period of depositional cycle.Keywords:  Lithostratigraphy, Sequence stratigraphy, Eustacy, Reservoir geology, Biostratigraphy, Ultra-deep Offshore, Eastern Niger Delta.DOI: 10.7176/JEES/10-7-06Publication date:July 31st 202

    Characterization of the interaction between HMGB1 and H3-a possible means of positioning HMGB1 in chromatin.

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    High mobility group protein B1 (HMGB1) binds to the internucleosomal linker DNA in chromatin and abuts the nucleosome. Bending and untwisting of the linker DNA results in transmission of strain to the nucleosome core, disrupting histone/DNA contacts. An interaction between H3 and HMGB1 has been reported. Here we confirm and characterize the interaction of HMGB1 with H3, which lies close to the DNA entry/exit points around the nucleosome dyad, and may be responsible for positioning of HMGB1 on the linker DNA. We show that the interaction is between the N-terminal unstructured tail of H3 and the C-terminal unstructured acidic tail of HMGB1, which are presumably displaced from DNA and the HMG boxes, respectively, in the HMGB1-nucleosome complex. We have characterized the interaction by nuclear magnetic resonance spectroscopy and show that it is extensive for both peptides, and appears not to result in the acquisition of significant secondary structure by either partner
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