Simplicial bounded cohomology and stability

We introduce a set of combinatorial techniques for studying the simplicial bounded cohomology of semi-simplicial sets, simplicial complexes and posets. We apply these methods to prove several new bounded acyclicity results for semi-simplicial sets appearing in the homological stability literature. Our strategy is to recast classical arguments (due to Bestvina, Maazen, van der Kallen, Vogtmann, Charney and, recently, Galatius--Randal-Williams) in the setting of bounded cohomology using uniformly bounded refinements of well-known simplicial tools. Combined with ideas developed by Monod and De la Cruz Mengual--Hartnick, we deduce slope-$1/2$ stability results for the bounded cohomology of two large classes of linear groups: general linear groups over any ring with finite Bass stable rank and certain automorphism groups of quadratic modules over the integers or any field of characteristic zero. We expect that many other results in the literature on homological stability admit bounded cohomological analogues by applying the blueprint provided in this work.Comment: 53 pages. Comments welcome

Apartment classes of integral symplectic groups

In this note we present an alternative proof of a theorem of Gunnells, which states that the Steinberg module of $\operatorname{Sp_{2n}}(\mathbb{Q})$ is a cyclic $\operatorname{Sp_{2n}}(\mathbb{Z})$-module, generated by integral apartment classes.Comment: 16 pages. Comments welcome

The homology of a Temperley-Lieb algebra on an odd number of strands

We show that the homology of any Temperley-Lieb algebra $\mathcal{TL}_n(a)$ on an odd number of strands vanishes in positive degrees. This improves a result obtained by Boyd-Hepworth. In addition we present alternative arguments for the following two vanishing results of Boyd-Hepworth. (1) The stable homology of Temperley-Lieb algebras is trivial. (2) If the parameter $a \in R$ is a unit, then the homology of any Temperley-Lieb algebra is concentrated in degree zero.Comment: 13 pages, 6 figures. Comments welcome

On the codimension-two cohomology of SLn(Z)\mathrm{SL}_n(\mathbb{Z})

Borel-Serre proved that $\mathrm{SL}_n(\mathbb{Z})$ is a virtual duality group of dimension $n \choose 2$ and the Steinberg module $\mathrm{St}_n(\mathbb{Q})$ is its dualizing module. This module is the top-dimensional homology group of the Tits building associated to $\mathrm{SL}_n(\mathbb{Q})$. We determine the "relations among the relations" of this Steinberg module. That is, we construct an explicit partial resolution of length two of the $\mathrm{SL}_n(\mathbb{Z})$-module $\mathrm{St}_n(\mathbb{Q})$. We use this partial resolution to show the codimension-2 rational cohomology group $H^{{n \choose 2} -2}(\mathrm{SL}_n(\mathbb{Z});\mathbb{Q})$ of $\mathrm{SL}_n(\mathbb{Z})$ vanishes for $n \geq 3$. This resolves a case of a conjecture of Church-Farb-Putman. We also produce lower bounds for the codimension-1 cohomology of certain congruence subgroups of $\mathrm{SL}_n(\mathbb{Z})$.Comment: 69 pages, 13 figure

BCOHTA 00:14T

The purpose of this review is to examine maternal serum triple-marker screening (TMS) for fetuses with Down syndrome, other chromosomal abnormalities, and spina bifida, in the British Columbia context. Evaluation is both qualitative, addressing the personal and social significance of TMS, and quantitative, assessing effectiveness and cost. The review is organized around the evaluation of four possible options for funding TMS. The first three options are in essence variations on current TMS practice in the province. A fourth option adds co-ordination of TMS, that is, provision, standardization, evaluation, and education throughout the province. In the interest of clarity, the options are discussed as much as possible in relation to Down syndrome, the most common condition traced through TMS. The review has been conducted with particular attention to the interests of groups who may in some respects be seen as vulnerable, women during pregnancy and members of the Down syndrome community; and also to the concerns of TMS providers. The issues examined are those relevant to large-scale population screening of women considered at low pre-test risk of carrying an affected fetus. Not addressed are issues of particular relevance to women identified as being at high pre-test risk owing to individual or family history of affected births.Arts, Faculty ofAnthropology and Sociology, Department ofHealth Care and Epidemiology, Department ofMedical Genetics, Department ofNon UBCMedicine, Faculty ofPopulation and Public Health (SPPH), School ofReviewedFacultyResearcherGraduat

Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes

BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo