Simple marked mesh patterns

In this paper we begin the first systematic study of distributions of simple marked mesh patterns. Mesh patterns were introduced recently by Br\"and\'en and Claesson in connection with permutation statistics. We provide explicit generating functions in several general cases, and develop recursions to compute the numbers in question in some other cases. Certain $q$-analogues are discussed. Moreover, we consider two modifications of the notion of a marked mesh pattern and provide enumerative results for them.Comment: 27 page

Singleton mesh patterns in multidimensional permutations

This paper introduces the notion of mesh patterns in multidimensional permutations and initiates a systematic study of singleton mesh patterns (SMPs), which are multidimensional mesh patterns of length 1. A pattern is avoidable if there exist arbitrarily large permutations that do not contain it. As our main result, we give a complete characterization of avoidable SMPs using an invariant of a pattern that we call its rank. We show that determining avoidability for a $d$-dimensional SMP $P$ of cardinality $k$ is an $O(d\cdot k)$ problem, while determining rank of $P$ is an NP-complete problem. Additionally, using the notion of a minus-antipodal pattern, we characterize SMPs which occur at most once in any $d$-dimensional permutation. Lastly, we provide a number of enumerative results regarding the distributions of certain general projective, plus-antipodal, minus-antipodal and hyperplane SMPs.Comment: Theorem 12 and Conjecture 1 are replaced by a more general Theorem 12; the paper is to appear in JCT

Distributions of several infinite families of mesh patterns

Br\"and\'en and Claesson introduced mesh patterns to provide explicit expansions for certain permutation statistics as linear combinations of (classical) permutation patterns. The first systematic study of avoidance of mesh patterns was conducted by Hilmarsson et al., while the first systematic study of the distribution of mesh patterns was conducted by the first two authors. In this paper, we provide far-reaching generalizations for 8 known distribution results and 5 known avoidance results related to mesh patterns by giving distribution or avoidance formulas for certain infinite families of mesh patterns in terms of distribution or avoidance formulas for smaller patterns. Moreover, as a corollary to a general result, we find the distribution of one more mesh pattern of length 2.Comment: 27 page

Distributions of mesh patterns of short lengths

A systematic study of avoidance of mesh patterns of length 2 was conducted in [I. Hilmarsson et al., Wilf-classification of mesh patterns of short length, Electr. J. Combin. 22(4) (2015), \#P4.13.], where 25 out of 65 non-equivalent cases were solved. In this paper, we give 27 distribution results for these patterns including 14 distributions for which avoidance was not known. Moreover, for the unsolved cases, we prove 2 equidistribution results (out of 7 equidistribution results we prove in total), and conjecture 7 more equidistributions. Finally, we find seemingly unknown distribution of the well known permutation statistic "strict fixed point", which plays a key role in many of our enumerative results. This paper is the first systematic study of distributions of mesh patterns. Our techniques to obtain the results include, but are not limited to obtaining functional relations for generating functions, and finding recurrence relations and bijections

The combinatorics of Jeff Remmel

We give a brief overview of the life and combinatorics of Jeff Remmel, a mathematician with successful careers in both logic and combinatorics

Survey of information on turbine bucket erosion

Turbine bucket erosion in steam, mercury, and potassium vapor turbines for use in space power plant

An assessment of the development of a cognitive research programme and introductions in zoo-housed chimpanzees

Zoological institutions emphasise the importance of excelling in the areas of animal welfare, conservation, education, and research, not only to better the lives of the animals under their care, but to also influence the general population in the pursuit to conserve the natural world. As a result, zoo life is anything but simple. This research project monitored the lives of a captive group of chimpanzees over a two-and-a-half-year period, during which time we explored four research topics while assessing the development of a cognitive research programme and chimpanzee (Pan troglodytes) introductions in a zoo: welfare, cognition, public engagement with science, and animal management. The project’s use of touchscreen technology and on-exhibit research was the first of its kind for the Royal Zoological Society of Scotland’s Edinburgh Zoo. As a result, the researchers placed a great deal of importance not only on assessing the welfare of the chimpanzees throughout training and testing phases, but also assessing the public’s perception of cognitive research being conducted through an internationally broadcast documentary about the project. In the short duration of the project, these research naïve chimpanzees did not fully grasp the concept of video selection in our free-choice activity, but overall, the introduction of a cognitive research programme did not compromise welfare, and the chimpanzees’ repeated interest suggests that chimpanzees found the research to be reinforcing. Partly funded by the BBC, the Chimpcam Project was shown in the UK (broadcast January 2010) and in a variety of other countries, including the United States and Canada (on Animal Planet in 2011). The broadcast allowed us to gather information over the internet on the wider public’s perception of conducting research with great apes in zoos, to complement data collected on visitors to the exhibit itself. Our assessment of the documentary’s impact on public perception showed that it had a positive influence on perceptions of zoo research, scientists, welfare, and the importance of choice for animals. During this research project, a new group of chimpanzees arrived in Edinburgh as part of the international breeding programme for western chimpanzees (Pan troglodytes verus). As the zoo’s focus switched to helping the two chimpanzee groups merge into one, we took the opportunity to apply psychological research to this context, namely the use of video as a research tool and the recognition of the importance of individual differences in response to challenge. The project maintained the cognition and welfare focus by using video introductions (allowing the chimpanzees to watch video footage of the individuals they were about to meet and track the formation of other sub-groups). In addition, personality ratings and chimpanzee behaviour during the visual access period (an animal management technique used prior to physical introductions where the groups could see each other without physical contact) were collected to examine the efficacy of these measures in guiding introductions in order to reduce risk. Personality ratings and behaviours observed during the video introductions could predict the chimpanzees’ behaviour during the physical introductions, however, the visual access period had no predictive power. The welfare implications of the introduction process were also assessed and suggested that: the choice of location (i.e. options of where to be) was more important than the total amount of available space; having individuals removed from your group was more stressful than having individuals added; self-directed behaviour (SDB) performance was context-specific where rubbing significantly increased during periods of uncertainty that were not necessarily negatively valenced; regurgitation and reingestion (R/R) decreased over time; and both in-group members and those of high ranks spent more time grooming others. Overall our data indicate that the chimpanzees coped well with both cognitive challenges and social upheaval during introductions. Despite being regularly studied in captivity and in the wild, chimpanzees have a great deal more to teach us about their world. In order to provide the best welfare for the chimpanzees in our care, we need to understand how research and management practices affect their lives and how the public interpret what we do as researchers. By understanding these aspects of their world, we can better serve those in captivity and influence public opinion on the importance of conserving those in the wild

Systematic review and meta-analysis of the growth and rupture rates of small abdominal aortic aneurysms: implications for surveillance intervals and their cost-effectiveness.

BACKGROUND: Small abdominal aortic aneurysms (AAAs; 3.0-5.4 cm in diameter) are usually asymptomatic and managed by regular ultrasound surveillance until they grow to a diameter threshold (commonly 5.5 cm) at which surgical intervention is considered. The choice of appropriate surveillance intervals is governed by the growth and rupture rates of small AAAs, as well as their relative cost-effectiveness. OBJECTIVES: The aim of this series of studies was to inform the evidence base for small AAA surveillance strategies. This was achieved by literature review, collation and analysis of individual patient data, a focus group and health economic modelling. DATA SOURCES: We undertook systematic literature reviews of growth rates and rupture rates of small AAAs. The databases MEDLINE, EMBASE on OvidSP, Cochrane Central Register of Controlled Trials 2009 Issue 4, ClinicalTrials.gov, and controlled-trials.com were searched from inception up until the end of 2009. We also obtained individual data on 15,475 patients from 18 surveillance studies. REVIEW METHODS: Systematic reviews of publications identified 15 studies providing small AAA growth rates, and 14 studies with small AAA rupture rates, up to December 2009 (later updated to September 2012). We developed statistical methods to analyse individual surveillance data, including the effects of patient characteristics, to inform the choice of surveillance intervals and provide inputs for health economic modelling. We updated an existing health economic model of AAA screening to address the cost-effectiveness of different surveillance intervals. RESULTS: In the literature reviews, the mean growth rate was 2.3 mm/year and the reported rupture rates varied between 0 and 1.6 ruptures per 100 person-years. Growth rates increased markedly with aneurysm diameter, but insufficient detail was available to guide surveillance intervals. Based on individual surveillance data, for each 0.5-cm increase in AAA diameter, growth rates increased by about 0.5 mm/year and rupture rates doubled. To control the risk of exceeding 5.5 cm to below 10% in men, on average a 7-year surveillance interval is sufficient for a 3.0-cm aneurysm, whereas an 8-month interval is necessary for a 5.0-cm aneurysm. To control the risk of rupture to below 1%, the corresponding estimated surveillance intervals are 9 years and 17 months. Average growth rates were higher in smokers (by 0.35 mm/year) and lower in patients with diabetes (by 0.51 mm/year). Rupture rates were almost fourfold higher in women than men, doubled in current smokers and increased with higher blood pressure. Increasing the surveillance interval from 1 to 2 years for the smallest aneurysms (3.0-4.4 cm) decreased costs and led to a positive net benefit. For the larger aneurysms (4.5-5.4 cm), increasing surveillance intervals from 3 to 6 months led to equivalent cost-effectiveness. LIMITATIONS: There were no clear reasons why the growth rates varied substantially between studies. Uniform diagnostic criteria for rupture were not available. The long-term cost-effectiveness results may be susceptible to the modelling assumptions made. CONCLUSIONS: Surveillance intervals of several years are clinically acceptable for men with AAAs in the range 3.0-4.0 cm. Intervals of around 1 year are suitable for 4.0-4.9-cm AAAs, whereas intervals of 6 months would be acceptable for 5.0-5.4-cm AAAs. These intervals are longer than those currently employed in the UK AAA screening programmes. Lengthening surveillance intervals for the smallest aneurysms was also shown to be cost-effective. Future work should focus on optimising surveillance intervals for women, studying whether or not the threshold for surgery should depend on patient characteristics, evaluating the usefulness of surveillance for those with aortic diameters of 2.5-2.9 cm, and developing interventions that may reduce the growth or rupture rates of small AAAs. FUNDING: The National Institute for Health Research Health Technology Assessment programme

Spatial and temporal distribution of shorebirds: predicting the effects of habitat change on the Forth Estuary.

First paragraph: Overview One of the many threats to coastal shorebirds globally is the loss or degradation of estuarine intertidal mudflats, a habitat that supports large concentrations of birds both on passage and throughout the winter months. British estuaries comprise 28% of the entire estuarine area of the Atlantic and North Sea coastal states (Atkinson et al. 2001), more than any other European country. Because of this, many UK estuaries are of great importance in both a European and international context for wintering birds (Pollitt et al. 2000). Furthermore, Britain’s estuaries can be particularly important during periods of severe cold weather in continental Europe (Norman & Coffey 1994), when there may be influxes of waterfowl from other coastal regions or inland areas. Some sites also act as cold weather refuges where parts of the estuarine system freeze more slowly than other nearby coastal and inland wetlands and so can provide feeding habitat when other sites are unavailable. Habitat change may not always mean habitat loss, even though large intertidal areas have been removed via landclaim (Evans 1979, McLusky et al. 1992) and engineering works (Schekkerman et al. 1994) or are threatened by the gradual rise in sea level (Austin et al. 2001). Determining the effects of habitat deterioration on shorebirds is often more difficult to predict (Sutherland 1998b) as, although the habitat remains intact, it may reduced in quality due to pollution events (McLusky 1982, McLusky & Martins 1998) or disturbance (Burger 1994, Burton 1996, West et al. 2002). The consequences of habitat change on estuaries are so potentially threatening to shorebird populations that programs of managed realignment (Burd 1995) have been introduced at some sites in order to mitigate such alteration (Dixon et al. 1998, French 1999, Hackney 2000). Such management activity involves the breaching of existing sea walls to allow the land behind to gradually return to estuarine habitat. It has been shown that invertebrates will colonise suitable intertidal habitats and that birds are quick to adapt to such new habitats (Evans et al. 1998)

Differential characterization of two novel antinematodal biological control agents : Streptomyces costaricus sp. nov. and a strain of Bacillus thuringiensis.

Two novel antinematodal strains of bacteria, Streptomyces sp. (CR-43) and Bacillus thuringiensis is (Bt) (CR-371) originating in Costa Rica were differentiated from other closely related strains and compared to rifampicin-resistant derivatives in greenhouse and field studies. The name Streptomyces costaricus is proposed for strain CR-43. The generic attribution was based on its typical morphology, production of LL-diaminopimelic acid and fatty acid composition. To clarify its taxonomic position, the isolate was compared with type strains of similar Streptomyces spp. The results of biochemical tests and profile analysis of hydrolyzable fatty acids indicated that CR-43 differed from previously described species and represents a new species. CR-43 (= ATCC 55274 = NRRL B-16897) is the type strain. A genotaxonomic approach to the differentiation of the streptomycetes was also taken. A modified RAPD analysis, conserved mini-sequence primed PCR (CMSP-PCR), was designed to target short conserved sequences dispersed throughout the streptomycete genome. All species had distinct DNA profiles when DNA was amplified with either 15-mer primer 5SSU3 (5\sp{\prime}-TGCGGCCGTACTCCC) or SSU5 (5\sp{\prime}-CGGCAGGCCTAACAC). The DNA profile of CR-43 resembled most that of S. h. decoyicus using primer SSU5. Species delineation was easily achieved with CMSP-PCR DNA amplification without further enzymatic processing. The differentiation of the novel Bt strain from five patented antinematodal Bt strains was required for patent prosecution. This was achieved by analysis of hydrolyzable fatty acid compositions of the strains by GC-MS and by DNA profile analysis. Thirty compounds in the total ion chromatograms were identified and analyzed using non-parametric statistics, the major fatty acids being i-15:0 (13.7-23.2%), i-13:0 (6.8-10.7%), i-14:0 (5.0-7.7%), 14:0 (3.0-4.1%), a-15:0 (3.9-9.9%), i-16:0 (3.6-7.2%), 16:0 (3.2-11.6%), i-17:0 (3.2-9.8%), 18:0 (tr-13.5%), a monounsaturated C16 (4.5-9.9%), a monounsaturated branched C17 (2.8-5.8%), a diunsaturated C18 (0-5.8%), and a monounsaturated C18 acid (0.3-4.8%). Molecular amplification of the DNA using a random nanomeric primer 5\sp{\prime}-CCGAGTCCA (that could discriminate serovars) showed that RAPD profiles of the Bt\u27s were different. Spontaneous rifampicin-resistance (rif\sp+) was selected in CR-371 and CR-43. Rif\sp+ had a positively pleiotropic effect on the biocontrol activity of the Bt strain and a negatively pleiotropic effect on the novel streptomycete. Rif\sp+ was a useful marker for monitoring survival of CR-371 and CR-43 in soil