The Topology of Parabolic Character Varieties of Free Groups

Let G be a complex affine algebraic reductive group, and let K be a maximal compact subgroup of G. Fix elements h_1,...,h_m in K. For n greater than or equal to 0, let X (respectively, Y) be the space of equivalence classes of representations of the free group of m+n generators in G (respectively, K) such that for each i between 1 and m, the image of the i-th free generator is conjugate to h_i. These spaces are parabolic analogues of character varieties of free groups. We prove that Y is a strong deformation retraction of X. In particular, X and Y are homotopy equivalent. We also describe explicit examples relating X to relative character varieties.Comment: 16 pages, version 2 includes minor revisions and some modified proofs, accepted for publication in Geometriae Dedicat

Detecting BS in Health Care 2.0

In our initial report “Detecting BS in Health Care,” we identified our top ten BS concepts and trends within the health care industry, and encouraged our readers to hone their “BS detection skills.” Many of you have let us know that we “left some BS on the table.” For example, there are more Old English terms for BS that we missed—such as babble, bafflegab, bilge, blather, blarney, bosh—and these are just from the b’s. This time around we make bolder assertions about other possible forms of BS—including some sacred cows—that might make some readers uncomfortable

Accountable Care Organizations: Back to the Future?

Accountable Care Organizations (ACOs) are networks of providers that assume risk for the quality and total cost of the care they deliver. Public policymakers and private insurers hope that ACOs will achieve the elusive “triple aim” of improving quality of care, improving population health, and reducing costs. The model is still evolving, but the premise is that ACOs will accomplish these aims by coordinating care, managing chronic disease, and aligning financial incentives for hospitals and physicians. If this sounds familiar, it may be because the integrated care networks of the 1990s tried some of the same things, and mostly failed in their attempts. This Issue Brief summarizes the similarities and differences between the new ACOs and the integrated delivery networks of the 1990s, and presents the authors’ analysis of the likely success of these new organizations in affecting the costs and quality of health care

Computing SL(2,C) Central Functions with Spin Networks

Let G=SL(2,C) and F_r be a rank r free group. Given an admissible weight in N^{3r-3}, there exists a class function defined on Hom(F_r,G) called a central function. We show that these functions admit a combinatorial description in terms of graphs called trace diagrams. We then describe two algorithms (implemented in Mathematica) to compute these functions.Comment: to appear in Geometriae Dedicat

Clinical placements in private practice for physiotherapy students are perceived as safe and beneficial for students, private practices and universities: a national mixed-methods study

Question: What are the extent and characteristics of clinical placements in private practice for physiotherapy students? What do university clinical education managers perceive to be the benefits, risks, barriers and enablers of clinical placements in private practice for physiotherapy students? What training and support are available for private practitioners? Design: Mixed methods study combining a national survey and in-depth, semi-structured focus group interviews. Participants: Twenty clinical education managers from Australian universities who had graduating students in entry-level physiotherapy programs in 2017 (95% response rate) responded to the survey with data on 2,000 students. Twelve clinical education managers participated in the focus groups. Results: It was found that 44% of physiotherapy graduates in Australia in 2017 completed a 5-week private practice placement. Private practice placement experiences were perceived to be safe and beneficial for students, private practices and universities. The main risks identified by clinical education managers were related to the quality and consistency of the student's experience on placement and not risks to service or clients. The main perceived barriers were time costs (both practitioner and university clinical education managers) and perceived lost earning capacity. Clinical education managers emphasised that more time and resources to establish and support private practitioners would enable them to reduce risk and overcome barriers to increasing private practice placement capacity and quality. Engaging private practitioners and working collaboratively appear vital for establishing, monitoring and supporting private practice placements. Conclusion: By working collaboratively, universities and private practice physiotherapists can enhance private practice placement capacity and quality

Comparison between four published definitions of hyposmia in Parkinson's disease

Objectives: Hyposmia is a common feature of Parkinson's disease (PD), yet there is no standard method to define it. A comparison of four published methods was performed to explore and highlight differences. // Materials and methods: Olfactory testing was performed in 2097 cases of early PD in two prospective studies. Olfaction was assessed using various cut-offs, usually corrected by age and/or gender. Control data were simulated based on the age and gender structure of the PD cases and published normal ranges. Association with age, gender, and disease duration was explored by method and study cohort. Prevalence of hyposmia was compared with the age and gender-matched simulated controls. Between method agreement was measured using Cohen's kappa and Gwet's AC1. // Results: Hyposmia was present in between 69.1% and 97.9% of cases in Tracking Parkinson's cases, and between 62.2% and 90.8% of cases in the Parkinson's Progression Marker Initiative, depending on the method. Between-method agreement varied (kappa 0.09–0.80, AC1 0.55–0.86). The absolute difference between PD cases and simulated controls was similar for men and women across methods. Age and male gender were positively associated with hyposmia (p < .001, all methods). Odds of having hyposmia increased with advancing age (OR:1.06, 95% CI:1.03, 1.10, p < .001). Longer disease duration had a negative impact on overall olfactory performance. // Conclusions: Different definitions of hyposmia give different results using the same dataset. A standardized definition of hyposmia in PD is required, adjusting for age and gender, to account for the background decline in olfactory performance with ageing, especially in men

Energy compensation in the real world. Good compensation for small portions of chocolate and biscuits over short time periods in complicit consumers using commercially available foods.

While investigations using covert food manipulations tend to suggest that individuals are poor at adjusting for previous energy intake, in the real world adults rarely consume foods with which they are ill-informed. This study investigated the impact in fully complicit consumers of consuming commercially available dark chocolate, milk chocolate, sweet biscuits and fruit bars on subsequent appetite. Using a repeated measures design, participants received four small portions (4 × 10-11 g) of either dark chocolate, milk chocolate, sweet biscuits, fruit bars or no food throughout five separate study days (counterbalanced in order), and test meal intake, hunger, liking and acceptability were measured. Participants consumed significantly less at lunch following dark chocolate, milk chocolate and sweet biscuits compared to no food (smallest t(19) = 2.47, p = 0.02), demonstrating very good energy compensation (269-334%). No effects were found for fruit bars (t(19) = 1.76, p = 0.09), in evening meal intakes (F(4,72) = 0.62, p = 0.65) or in total intake (lunch + evening meal + food portions) (F(4,72) = 0.40, p = 0.69). No differences between conditions were found in measures of hunger (largest F(4,76) = 1.26, p = 0.29), but fruit bars were significantly less familiar than all other foods (smallest t(19) = 3.14, p = 0.01). These findings demonstrate good compensation over the short term for small portions of familiar foods in complicit consumers. Findings are most plausibly explained as a result of participant awareness and cognitions, although the nature of these cognitions cannot be discerned from this study. These findings however, also suggest that covert manipulations may have limited transfer to real world scenarios

Ballistic transport in random magnetic fields with anisotropic long-ranged correlations

We present exact theoretical results about energetic and dynamic properties of a spinless charged quantum particle on the Euclidean plane subjected to a perpendicular random magnetic field of Gaussian type with non-zero mean. Our results refer to the simplifying but remarkably illuminating limiting case of an infinite correlation length along one direction and a finite but strictly positive correlation length along the perpendicular direction in the plane. They are therefore ``random analogs'' of results first obtained by A. Iwatsuka in 1985 and by J. E. M\"uller in 1992, which are greatly esteemed, in particular for providing a basic understanding of transport properties in certain quasi-two-dimensional semiconductor heterostructures subjected to non-random inhomogeneous magnetic fields