Diagonal Riccati Stability and Applications

We consider the question of diagonal Riccati stability for a pair of real matrices A, B. A necessary and sufficient condition for diagonal Riccati stability is derived and applications of this to two distinct cases are presented. We also describe some motivations for this question arising in the theory of generalised Lotka-Volterra systems

Representations of the Symmetric Group and Nonstandard Quantum Statistics

From the Washington University Senior Honors Thesis Abstracts (WUSHTA), Spring 2018. Published by the Office of Undergraduate Research. Joy Zalis Kiefer, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Lindsey Paunovich, Editor; Helen Human, Programs Manager and Assistant Dean in the College of Arts and Sciences Mentor: Renato Fere

Momentum Control with Hierarchical Inverse Dynamics on a Torque-Controlled Humanoid

Hierarchical inverse dynamics based on cascades of quadratic programs have been proposed for the control of legged robots. They have important benefits but to the best of our knowledge have never been implemented on a torque controlled humanoid where model inaccuracies, sensor noise and real-time computation requirements can be problematic. Using a reformulation of existing algorithms, we propose a simplification of the problem that allows to achieve real-time control. Momentum-based control is integrated in the task hierarchy and a LQR design approach is used to compute the desired associated closed-loop behavior and improve performance. Extensive experiments on various balancing and tracking tasks show very robust performance in the face of unknown disturbances, even when the humanoid is standing on one foot. Our results demonstrate that hierarchical inverse dynamics together with momentum control can be efficiently used for feedback control under real robot conditions.Comment: 21 pages, 11 figures, 4 tables in Autonomous Robots (2015

Motion of a vortex line near the boundary of a semi-infinite uniform condensate

We consider the motion of a vortex in an asymptotically homogeneous condensate bounded by a solid wall where the wave function of the condensate vanishes. For a vortex parallel to the wall, the motion is essentially equivalent to that generated by an image vortex, but the depleted surface layer induces an effective shift in the position of the image compared to the case of a vortex pair in an otherwise uniform flow. Specifically, the velocity of the vortex can be approximated by $U \approx (\hbar/2m)(y_0-\sqrt 2 \xi)^{-1}$, where $y_0$ is the distance from the center of the vortex to the wall, $\xi$ is the healing length of the condensate and $m$ is the mass of the boson.Comment: submitted to Phys Rev

Development Strategies for Animal Medical Therapeutics

The process of developing a new therapeutic is long, expensive, and risky. Current small animal models are often poor representations of human disease, contributing to the high rate of failure in human trials. Outbred dogs can be excellent models for researching human disease. Clinical trials in dogs are inexpensive and efficient compared with human trials. Advaxis, a clinical-stage biotechnology company developing cancer immunotherapies, provides one case study on how trials in dogs can help advance trials in humans

X-ray and optical variability of Seyfert 1 galaxies as observed with XMM-Newton

We have examined simultaneous X-ray and optical light curves of a sample of eight nearby Seyfert 1 galaxies observed using the EPIC X-ray cameras and Optical Monitor on board XMM. The observations span ~1 day and revealed optical variability in four of the eight objects studied. In all cases, the X-ray variability amplitude exceeded that of the optical both in fractional and absolute luminosity terms. No clearly significant correlations were detected between wavebands using cross correlation analysis. We conclude that, in three of the four objects in which optical variability was detected, reprocessing mechanisms between wavebands do not dominate either the optical or X-ray variability on the time-scales probed.Comment: 9 pages, 2 figures, accepted for publication in MNRA

EEG Correlates of Consciousness During Sleep: A Pilot Study

The following is an abstract of a pilot study posted in the corollary sessions at the Lucidity Association's Conference on Higher States of Consciousness, in Chicago in July, 1990

Working the crowd : improvisational entrepreneurship and equity crowdfunding in nascent entrepreneurial ventures

Equity crowdfunding has rapidly established itself as an important part of the funding landscape for nascent entrepreneurial ventures. To date, however, little is known about the nature of the demand for equity crowdfunding or its impact on recipient firms. This paper draws on an interview-based study of entrepreneurs in 42 equity crowdfunded start-ups in the UK. The study found strong demand for this funding from these experimental and improvisational entrepreneurs within innovative, consumer-focused, early stage firms. Many entrepreneurs were classic “discouraged borrowers” attracted by the ability to obtain finance quickly with relatively little diminution of their equity or autonomy. In terms of impact, equity crowdfunding seems to confer important intangible benefits to investee companies which amount to more than money. Given their strongly improvisational nature, the concept of entrepreneurial bricolage seems a suitable theoretical lens explicating the behavioural aspects of the entrepreneurs examined.PostprintPeer reviewe