Ultra-Compact Motor Controller

This invention is an electronically commutated brushless motor contro ller that incorporates Hall-array sensing in a small, 42-gram packag e that provides 4096 absolute counts per motor revolution position s ensing. The unit is the size of a miniature hockey puck, and is a 44 -pin male connector that provides many I/O channels, including CANbus , RS-232 communications, general-purpose analog and digital I/O (GPI O), analog and digital Hall inputs, DC power input (18-90 VDC, 0-l0 A), three-phase motor outputs, and a strain gauge amplifier

Homogeneous links, Seifert surfaces, digraphs and the reduced Alexander polynomial

We give a geometric proof of the following result of Juhasz. \emph{Let $a_g$ be the leading coefficient of the Alexander polynomial of an alternating knot $K$. If $|a_g|<4$ then $K$ has a unique minimal genus Seifert surface.} In doing so, we are able to generalise the result, replacing `minimal genus' with `incompressible' and `alternating' with `homogeneous'. We also examine the implications of our proof for alternating links in general.Comment: 37 pages, 28 figures; v2 Main results generalised from alternating links to homogeneous links. Title change

Elastic energy of polyhedral bilayer vesicles

In recent experiments [M. Dubois, B. Dem\'e, T. Gulik-Krzywicki, J.-C. Dedieu, C. Vautrin, S. D\'esert, E. Perez, and T. Zemb, Nature (London) Vol. 411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T. Gulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc. Natl. Acad. Sci. U.S.A. Vol. 101, 15082 (2004)] that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron

The Jones polynomial and graphs on surfaces

The Jones polynomial of an alternating link is a certain specialization of the Tutte polynomial of the (planar) checkerboard graph associated to an alternating projection of the link. The Bollobas-Riordan-Tutte polynomial generalizes the Tutte polynomial of planar graphs to graphs that are embedded in closed oriented surfaces of higher genus. In this paper we show that the Jones polynomial of any link can be obtained from the Bollobas-Riordan-Tutte polynomial of a certain oriented ribbon graph associated to a link projection. We give some applications of this approach.Comment: 19 pages, 9 figures, minor change

Cognition and Academic Performance of Division II Football Players During Noncompetitive and Competitive Seasons

Introduction Background: Repetitive head impacts (RHIs) are multiple sub-concussive forces that may result from either a direct or indirect impact to the head or body over a period of time that result with no presence of symptoms immediately following the mechanism. Football players are at an increased risk of repeated head injuries. Athletes who have experienced RHIs are hypothesized to have increased negative effects on their academic tolerance, mental health, and cognition compared to their peers. Purpose: The purpose of this study is to compare the cognition, mental health, and academic tolerance of Division II football players during a non-competitive (2020) and competitive (2021) season. Methods Participants: 30 Division II football players from Concordia University, St. Paul with a mean age of 20.5 +/- 1.22 years and a range of 19 - 23. Tests and Measures: Paced Auditory Serial Addition Test (PASAT) for working memory Center for Epidemiological Studies Depression Scale (CES-D) Demographic survey Personal interview Data Analysis: Qualitative interviews were recorded, transcribed and de-identified then coded and analyzed on NVIVO-12 PASAT and CES-D data were both analyzed on SPSS-28, using a Wilcoxon Signed Rank Test Major Themes Effortful Mental Activity: Cognitive exertion associated with prolonged academic demand. Attention: The ability to sustain focus on a given task. Sensitivity to Stimuli: Increased responsiveness or vulnerability to sensory input. Headaches: A painful sensation localized to the head region. Slow Processing: Increased time required to interpret, process, and respond to information or stimuli. Fatigue: Physical or mental exhaustion due to internal or external sources. Memory: The ability to recall past events or facts learned previously. Sleep Difficulty: Inconsistent or frequently interrupted sleeping habits. Conclusion While group cognition scores increased between years, some participants consistently scored below the age and education-based normative mean score. Players continue to complain of cognitive changes and worsening depressive symptoms that are consistent with what is expected from an individual suffering from a concussion though players were not actively concussed at the time of measurement. Clinical Relevance There is a potential for cognition to heal or improve as evidenced by the improvement in group cognitive scores, but the long-term effects are still largely unknown. There may be a neuroprotective effect of exercise, as well as a high learning effect associated with the PASAT that may have impacted results. Depressive symptoms worsened over time which should warrant further study. The potential for academic struggles from RHI for collegiate football players should not be ruled out despite quantitative findings

Effectiveness of a quality improvement collaborative in reducing time to surgery for patients requiring emergency cholecystectomy.

Background:Acute gallstone disease is a high-volume emergency general surgery presentation with wide variations in the quality of care provided across the UK. This controlled cohort evaluation assessed whether participation in a quality improvement collaborative approach reduced time to surgery for patients with acute gallstone disease to fewer than 8 days from presentation, in line with national guidance. Methods:Patients admitted to hospital with acute biliary conditions in England and Wales between 1 April 2014 and 31 December 2017 were identified from Hospital Episode Statistics data. Time series of quarterly activity were produced for the Cholecystectomy Quality Improvement Collaborative (Chole-QuIC) and all other acute National Health Service hospitals (control group). A negative binomial regression model was used to compare the proportion of patients having surgery within 8 days in the baseline and intervention periods. Results:Of 13 sites invited to join Chole-QuIC, 12 participated throughout the collaborative, which ran from October 2016 to January 2018. Of 7944 admissions, 1160 patients had a cholecystectomy within 8 days of admission, a significant improvement (P < 0·050) from baseline performance. This represented a relative change of 1·56 (95 per cent c.i. 1·38 to 1·75), compared with 1·08 for the control group. At the individual site level, eight of the 12 Chole-QuIC sites showed a significant improvement (P < 0·050), with four sites increasing their 8-day surgery rate to over 20 per cent of all emergency admissions, well above the mean of 15·3 per cent for control hospitals. Conclusion:A surgeon-led quality improvement collaborative approach improved care for patients requiring emergency cholecystectomy