Nonpositively curved 2-complexes with isolated flats

We introduce the class of nonpositively curved 2-complexes with the Isolated Flats Property. These 2-complexes are, in a sense, hyperbolic relative to their flats. More precisely, we show that several important properties of Gromov-hyperbolic spaces hold `relative to flats' in nonpositively curved 2-complexes with the Isolated Flats Property. We introduce the Relatively Thin Triangle Property, which states roughly that the fat part of a geodesic triangle lies near a single flat. We also introduce the Relative Fellow Traveller Property, which states that pairs of quasigeodesics with common endpoints fellow travel relative to flats, in a suitable sense. The main result of this paper states that in the setting of CAT(0) 2-complexes, the Isolated Flats Property is equivalent to the Relatively Thin Triangle Property and is also equivalent to the Relative Fellow Traveller Property.Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol8/paper5.abs.htm

Homogenization via formal multiscale asymptotics and volume averaging: How do the two techniques compare?

A wide variety of techniques have been developed to homogenize transport equations in multiscale and multiphase systems. This has yielded a rich and diverse field, but has also resulted in the emergence of isolated scientific communities and disconnected bodies of literature. Here, our goal is to bridge the gap between formal multiscale asymptotics and the volume averaging theory. We illustrate the methodologies via a simple example application describing a parabolic transport problem and, in so doing, compare their respective advantages/disadvantages from a practical point of view. This paper is also intended as a pedagogical guide and may be viewed as a tutorial for graduate students as we provide historical context, detail subtle points with great care, and reference many fundamental works

8th International Workshop on Mining Scientific Publications (WOSP 2020)

The entire body of research literature is currently estimated at 100-150 million publications with an annual increase of around 1.5 million. Systematically reading and analysing the full body of knowledge is now beyond the capacities of any human being. Consequently, it is important to better understand how we can leverage Natural Language Processing/Text Mining techniques to aid knowledge creation and improve the process by which research is being done. This workshop aims to bring together people from different backgrounds who: (a) have experience with analysing and mining databases of scientific publications, (b) develop systems that enable such analysis and mining of scientific databases (especially those who manage publication databases) or (c) who develop novel technologies that improve the way research is being done

The effect of methane hydrate morphology and water saturation on seismic wave attenuation in sand under shallow sub-seafloor conditions

A better understanding of seismic wave attenuation in hydrate-bearing sediments is needed for the improved geophysical quantification of seafloor methane hydrates, important for climate change, geohazard and economic resource assessment. Hence, we conducted a series of small strain (<10−6), seismic frequency (50–550 Hz), laboratory resonant column experiments on synthetic methane hydrate-bearing sands under excess-water seafloor conditions. The results show a complex dependence of P- and S-wave attenuation on hydrate saturation and morphology. P- and S-wave attenuation in excess-water hydrate-bearing sand is much higher than in excess-gas hydrate-bearing sand and increases with hydrate saturation between 0 and 0.44 (the experimental range). Theoretical modelling suggests that load-bearing hydrate is an important cause of heightened attenuation for both P- and S-waves in gas and water saturated sands, while pore-filling hydrate also contributes significantly to P-wave attenuation in water saturated sands. A squirt flow attenuation mechanism, related to microporous hydrate and low aspect ratio pores at the interface between sand grains and hydrate, is thought to be responsible for the heightened levels of attenuation in hydrate-bearing sands at low hydrate saturations (<0.44)

The distribution of polysaccharide-specific antibody-secreting and memory B cells against the four polysaccharides.

<p>The number of PS-specific ASCs (A) and MBCs (B) specific for each antigen at days 0, 7 and 28 post-vaccination are depicted. The radius of each circle in the center panel is proportional to the number of PS-specific ASCs or MBCs detected, and the antigen specificity is indicated by the color of each circle. The antigen distribution for all ASCs and MBCs within each vaccine-group are depicted in pie charts. Numbers in the center of the pie charts indicate the total numbers of ASCs or MBCs detected. The distribution of antigen specificity was compared using a 2XN Fisher’s test.</p

Developmental exposure to near roadway pollution produces behavioral phenotypes relevant to neurodevelopmental disorders in juvenile rats.

Epidemiological studies consistently implicate traffic-related air pollution (TRAP) and/or proximity to heavily trafficked roads as risk factors for developmental delays and neurodevelopmental disorders (NDDs); however, there are limited preclinical data demonstrating a causal relationship. To test the effects of TRAP, pregnant rat dams were transported to a vivarium adjacent to a major freeway tunnel system in northern California where they were exposed to TRAP drawn directly from the face of the tunnel or filtered air (FA). Offspring remained housed under the exposure condition into which they were born and were tested in a variety of behavioral assays between postnatal day 4 and 50. To assess the effects of near roadway exposure, offspring of dams housed in a standard research vivarium were tested at the laboratory. An additional group of dams was transported halfway to the facility and then back to the laboratory to control for the effect of potential transport stress. Near roadway exposure delayed growth and development of psychomotor reflexes and elicited abnormal activity in open field locomotion. Near roadway exposure also reduced isolation-induced 40-kHz pup ultrasonic vocalizations, with the TRAP group having the lowest number of call emissions. TRAP affected some components of social communication, evidenced by reduced neonatal pup ultrasonic calling and altered juvenile reciprocal social interactions. These findings confirm that living in close proximity to highly trafficked roadways during early life alters neurodevelopment

The heavy-chain gene-family usage and CDR3 length of polysaccharide-specific memory B cells.

<p>Sequences recovered from PS-specific MBCs were analyzed by IMGT/HighV-QUEST using the rhesus macaque immunoglobulin database. The heavy chain alleles of each B cell were generated by RT-PCR. (A) Heavy-chain gene-family usage at day 0 and 7 after immunization with 23vPS or 13vPnC. The number in the pie chart is the average number of variable sequences recovered from PS-specific MBCs. Pairwise statistical analysis was performed by Fisher’s Exact Test. (B) Distribution of heavy-chain gene-family usage for each PS serotype from PS-specific MBCs at 7 days following immunization with 13vPnC. The number in the pie chart is the average number of PS-specific MBCs against each antigen. Statistical analysis was performed by Fisher’s Exact Test. (C) The average CDR3 amino acid length of PS-specific MBCs at 0 and 7 days after immunization.</p

The distribution of polysaccharide-specific antibody-secreting and memory B cells against the four polysaccharides.

<p>The number of PS-specific ASCs (A) and MBCs (B) specific for each antigen at days 0, 7 and 28 post-vaccination are depicted. The radius of each circle in the center panel is proportional to the number of PS-specific ASCs or MBCs detected, and the antigen specificity is indicated by the color of each circle. The antigen distribution for all ASCs and MBCs within each vaccine-group are depicted in pie charts. Numbers in the center of the pie charts indicate the total numbers of ASCs or MBCs detected. The distribution of antigen specificity was compared using a 2XN Fisher’s test.</p