Structured specifications for better verification of heap-manipulating programs

Abstract. Conventional specifications typically have a flat structure that is based primarily on the underlying logic. Such specifications lack structures that could have provided better guidance to the verification process. In this work, we propose to add three new structures to a specification framework for separation logic to achieve a more precise and better guided verification for pointer-based programs. The newly introduced structures empower users with more control over the verification process in the following ways: (i) case analysis can be invoked to take advantage of disjointness conditions in the logic. (ii) early, as opposed to late, instantiation can minimise on the use of existential quantification. (iii) formulae that are staged provide better reuse of the verification process. Initial experiments have shown that structured specifications can lead to more precise verification without incurring any performance overhead.

Gravitino constraints on models of neutrino masses and leptogenesis

In the supersymmetric extensions of the standard model, neutrino masses and leptogenesis requires existence of new particles. We point out that if these particles with lepton number violating interactions have standard model gauge interactions, then they may not be created after reheating because of the gravitino problem. This will rule out all existing models of neutrino masses and leptogenesis, except the one with right-handed singlet neutrinos.Comment: 12 pages latex file with one postscript figur

Fractional Quantum Hall Effect via Holography: Chern-Simons, Edge States, and Hierarchy

We present three holographic constructions of fractional quantum Hall effect (FQHE) via string theory. The first model studies edge states in FQHE using supersymmetric domain walls in N=6 Chern-Simons theory. We show that D4-branes wrapped on CP^1 or D8-branes wrapped on CP^3 create edge states that shift the rank or the level of the gauge group, respectively. These holographic edge states correctly reproduce the Hall conductivity. The second model presents a holographic dual to the pure U(N)_k (Yang-Mills-)Chern-Simons theory based on a D3-D7 system. Its holography is equivalent to the level-rank duality, which enables us to compute the Hall conductivity and the topological entanglement entropy. The third model introduces the first string theory embedding of hierarchical FQHEs, using IIA string on C^2/Z_n.Comment: 36 pages, 6 figures; v2: with an improved derivation of Hall conductivity in section 3.2, typo corrections, and additional references; v3: explanations and comments adde

Contribution of plasma cells and B cells to hidradenitis suppurativa pathogenesis

Hidradenitis suppurativa (HS) is a debilitating chronic inflammatory skin disease characterized by chronic abscess formation and development of multiple draining sinus tracts in the groin, axillae, and perineum. Using proteomic and transcriptomic approaches, we characterized the inflammatory responses in HS in depth, revealing immune responses centered on IFN-γ, IL-36, and TNF, with lesser contribution from IL-17A. We further identified B cells and plasma cells, with associated increases in immunoglobulin production and complement activation, as pivotal players in HS pathogenesis, with Bruton’s tyrosine kinase (BTK) and spleen tyrosine kinase (SYK) pathway activation as a central signal transduction network in HS. These data provide preclinical evidence to accelerate the path toward clinical trials targeting BTK and SYK signaling in moderate-to-severe HS

What causes hidradenitis suppurativa ?—15 years after

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30–April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote “Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy.” (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, th

Attitude Manoeuvring Under Dynamic Path and Time Constraints for Formation Flying Nanosatellites

Large angle attitude manoeuvres are often subjected to dynamic and celestial path constraints such as maintaining ground link communication, GPS lock, or Sun avoidance while tracking various primary targets in real time. Considered in this paper is an onboard approach to maximizing the signal lock with GPS satellites with a restricted antenna field of view while tracking primary attitude targets. The proposed time optimal attitude controller does not require a priori knowledge of the target(s) and avoids the time and computational requirements of typical avoidance and random search techniques. Included in this paper are the attitude requirements to maintain GPS lock as derived from ground based and on orbit experiments as well as the proposed controller and the results of numerical simulations. This controller has been developed for the Canadian Advanced Nanosatellite eXperiment (CanX) 4 and 5 satellites currently under development at the University of Toronto’s Space Flight Laboratory. CanX-4 and CanX- 5 are identical satellites that will be launched together and will make use of differential GPS measurements and a cold gas propulsion system to demonstrate autonomous sub-meter control formation flying based on differential GPS Measurements

Arc-Minute Attitude Stability on a Nanosatellite: Enabling Stellar Photometry on the Smallest Scale

The precision of astronomy and stellar photometry missions is strongly influenced by the attitude stability of the instrument platform. Recent developments in the miniaturization of star trackers and reaction wheels have opened the possibility of performing precise stellar photometry with nanosatellites. The BRIght Target Explorer (BRITE) mission uses a constellation of six nanosatellites that will photometrically observe the brightest stars in the sky. Each BRITE satellite will use a CCD imager with a 3-cm aperture telescope. The small telescope is capable of making photometric measurements with precision of 0.1%. This photometric precision is in part made possible by reacquiring target stars using the same set of pixels for multiple observations. This reacquisition requirement implies arc-minute attitude stability. To accomplish this requirement the attitude is controlled by an orthogonal set of three reaction wheels, and estimated with a star tracker, developed jointly by Sinclair Interplanetary, Ryerson University’s SAIL facility and the Space Flight Laboratory. This paper focuses on the challenges of and solutions to three-axis arc-minute pointing stability on the nanosatellite scale. Special attention is given to the effect of reaction wheel jitter, the practical limitations associated with miniaturized star trackers, and attitude estimation without the use of rate gyros. The solutions presented apply to small satellites in general, including BRITE constellation. The first satellites in BRITE Constellation are scheduled to launch in late 2011

Bronchodilatory and anti-inflammatory properties of inhaled selective phosphodiesterase inhibitors in a guinea pig model of allergic asthma

In a guinea pig model of allergic asthma, we investigated the effects of the selective phosphodiesterase inhibitors rolipram (phosphodiesterase 4-selective), Org 9935 (phosphodiesterase 3-selective) and Org 20241 (dual phosphodiesterase 4/phosphodiesterase 3-selective), administered by aerosol inhalation in approximately equipotent bronchodilatory doses, on allergen-induced early and late asthmatic reactions, airway hyperreactivity and airway inflammation. Using ovalbumin-sensitized non-challenged animals, different nebulizer concentrations of each inhibitor were tested for their protective effects against histamine-induced bronchoconstriction. Inhalation of 2.5 mM rolipram, 100 mM 4,5-dihydro-6-(5,6-dimethoxybenzo[b]thien-2-yl-5-methyl-3(2H)pyridazinone (Org: 9935) and 10 and 100 mM N-hydroxy-4-(3,4-dimethoxyphenyl)-thiazole-2-carboximidamide HCl (Org 20241) provided a similar, 1.8-fold (P <0.01), 2.0-fold (P <0.05), and 1.8- and 1.9-fold (P <0.05) protection, respectively. The duration of these bronchoprotective effects were different, the rate of decline being faster with rolipram and the lower Org 20241 concentration than with Org 9935 and the higher concentration of Org 20241. All compounds strongly protected against the immediate allergen-induced bronchoconstriction and significantly (P <0.05) diminished the overall early asthmatic reaction from 0 to 6 h following allergen-provocation. The severity of the late asthmatic reaction was also significantly inhibited by rolipram (P 0.05) and Org 9935 (P <0.05). Allergen-induced airway hyperreactivity to inhaled histamine after the early reaction, at 6 h after ovalbumin challenge, was strongly reduced by rolipram (P <0.05) and completely prevented by the two other phosphodiesterase inhibitors; in addition, airway hyperreactivity after the late asthmatic reaction, at 24 h, was abolished in all treatment groups. Bronchoalveolar lavage performed at 24 h after allergen challenge revealed no inhibition of eosinophil infiltration in the rolipram-treated animals, whereas inhalation of Org 9935 and the higher-but not the lower-concentration of Org, 20241 strongly reduced the influx of these cells. Eosinophil peroxidase activity in the lavage fluid tended to be diminished in all treatment groups but significance was not reached with the exception of the lower concentration of Org 20241. Infiltration of lymphocytes and macrophages was significantly inhibited by Org 9935 only (P <0.05 and P <0.01, respectively), whereas neutrophil influx was not significantly affected. The results indicate that inhalation of phosphodiesterase 3-, phosphodiesterase 4- and dual phosphodiesterase 3/phospbodiesterase 4-selective inhibitors afford protection against acute histamine- and allergen-induced bronchoconstriction and prevent the development of airway hyperreactivity both after the early and late asthmatic reaction predominantly through inhibition of phosphodiesterase 4; in contrast, for significant reduction Of eosidophil infiltration, both phosphodiesterase 3 and phosphodiesterase 4 inhibition seems to be required. (C) 2001 Elsevier Science B.V. All rights reserved

An Affordable, Low-Risk Approach to Launching Research Spacecraft as Tertiary Payloads

Rapid and affordable access to space for university researchers and educators has always been a challenge. Despite the availability of lower-cost (e.g. Russian) launch vehicles, launching payloads 20 kg or less typically involves a certain minimum cost that necessitates a cost sharing arrangement among numerous parties and the handling of complex export control issues. In turn, this complicates mission scheduling and increases the risk of missing launch deadlines. The University of Toronto Institute for Aerospace Studies, Space Flight Laboratory (UTIAS/SFL) has taken a leading role in addressing this challenge, and has successfully led a group of international spacecraft developers in manifesting one 1-kg Canadian spacecraft, two 1- kg Danish spacecraft, and one 3-kg American spacecraft on a 2003 Eurockot launch. This paper outlines the approach taken by UTIAS/SFL in negotiating and securing launches for its own spacecraft in collaboration with other spacecraft developers. A summary of how this approach is applied in planning and coordinating the June 2003 Eurockot launch is also presented