Positivity of Quasilocal Mass

Motivated by the important work of Brown adn York on quasilocal energy, we propose definitions of quasilocal energy and momentum surface energy of a spacelike 2-surface with positive intrinsic curvature in a spacetime. We show that the quasilocal energy of the boundary of a compact spacelike hypersurface which satisfies the local energy condition is strictly positive unless the spacetime is flat along the spacelike hypersurface.Comment: 4 pages; final published versio

Some Comments on Gravitational Entropy and the Inverse Mean Curvature Flow

The Geroch-Wald-Jang-Huisken-Ilmanen approach to the positive energy problem to may be extended to give a negative lower bound for the mass of asymptotically Anti-de-Sitter spacetimes containing horizons with exotic topologies having ends or infinities of the form $\Sigma_g \times {\Bbb R}$, in terms of the cosmological constant. We also show how the method gives a lower bound for for the mass of time-symmetric initial data sets for black holes with vectors and scalars in terms of the mass, $|Z(Q,P)|$ of the double extreme black hole with the same charges. I also give a lower bound for the area of an apparent horizon, and hence a lower bound for the entropy in terms of the same function $|Z(Q,P)|$. This shows that the so-called attractor behaviour extends beyond the static spherically symmetric case. and underscores the general importance of the function $|Z(Q,P)|$. There are hints that higher dimensional generalizations may involve the Yamabe conjectures.Comment: 13pp. late

Visual speech recognition and utterance segmentation based on mouth movement

This paper presents a vision-based approach to recognize speech without evaluating the acoustic signals. The proposed technique combines motion features and support vector machines (SVMs) to classify utterances. Segmentation of utterances is important in a visual speech recognition system. This research proposes a video segmentation method to detect the start and end frames of isolated utterances from an image sequence. Frames that correspond to `speaking' and `silence' phases are identified based on mouth movement information. The experimental results demonstrate that the proposed visual speech recognition technique yields high accuracy in a phoneme classification task. Potential applications of such a system are, e.g., human computer interface (HCI) for mobility-impaired users, lip-reading mobile phones, in-vehicle systems, and improvement of speech-based computer control in noisy environments

Association between fire-safe cigarette legislation and residential fire deaths in the United States

Abstract: Background: Cigarettes and other tobacco-related smoking products have traditionally been a major ignition source for residential fire deaths. In the United States, all 50 states and the District of Columbia have passed laws requiring that cigarettes self-extinguish if they are not being smoked (so-called fire-safe cigarette laws). The purpose of this study was to quantify the association between state-level implementation of fire-safe cigarette legislation and the rate of residential fire death. Methods: Poisson regression was used to analyze state-years data. Main intervention: Implementation dates for fire-safe cigarette legislation in each state. Outcome: Residential fire mortality rate. Results: Implementation of fire-safe cigarette legislation was associated with a 19% reduction in overall residential fire mortality rates, adjusted for demographic differences between states (rate ratio = 0.81, 95% confidence interval: 0.79, 0.84). This is approximately similar to the estimated proportion of residential fire deaths in which smoking materials are an ignition source (23%). Legislation implementation was associated with a protective effect for every age, sex, race, and ethnicity strata that we examined. State-specific residential fire mortality death rates decreased (defined as a drop of at least 5%) in 32 states after fire-safe cigarette legislation was implemented. In 12 states there was either less than a 5% decrease or an increase, and seven states had insufficient deaths to evaluate state-level changes. Conclusions: Implementation of fire-safe cigarette is associated with reductions in residential fire mortality rates

Construction of n-Lie algebras and n-ary Hom-Nambu-Lie algebras

We present a procedure to construct (n+1)-Hom-Nambu-Lie algebras from n-Hom-Nambu-Lie algebras equipped with a generalized trace function. It turns out that the implications of the compatibility conditions, that are necessary for this construction, can be understood in terms of the kernel of the trace function and the range of the twisting maps. Furthermore, we investigate the possibility of defining (n+k)-Lie algebras from n-Lie algebras and a k-form satisfying certain conditions

Local amplification of glucocorticoids in the aging brain and impaired spatial memory

The hippocampus is a prime target for glucocorticoids (GCs) and a brain structure particularly vulnerable to ageing. Prolonged exposure to excess GCs compromises hippocampal electrophysiology, structure and function. Blood GC levels tend to increase with ageing and correlate with impaired spatial memory in ageing rodents and humans. The magnitude of GC action within tissues depends not only on levels of steroid hormone that enter the cells from the periphery and the density of intracellular receptors but also on the local metabolism of GCs by 11ß-hydroxysteroid dehydrogenases (11ß-HSD). The predominant isozyme in the adult brain, 11ß-HSD1, locally regenerates active GCs from inert 11-keto forms thus amplifying GC levels within specific target cells including in the hippocampus and cortex. Ageing associates with elevated hippocampal and neocortical 11ß-HSD1 and impaired spatial learning while deficiency of 11ß-HSD1 in knockout mice prevents the emergence of cognitive decline with age. Furthermore, short-term pharmacological inhibition of 11ß-HSD1 in already aged mice reverses spatial memory impairments. Here, we review research findings that support a key role for GCs with special emphasis on their intracellular regulation by 11ß-HSD1 in the emergence of spatial memory deficits with ageing, and discuss the use of 11ß-HSD1 inhibitors as a promising novel treatment in ameliorating/improving age-related memory impairments

Boundary control of a rotating Timoshenko beam

The boundary control of a rotating beam is investigated. The beam is modelled by the Timoshenko beam equations, which are a system of two coupled wave equations that include the effects of shearing and the rotational inertia of cross-sections of the beam. The beam, which is pivoted at one end and free at the other, has physical parameters that may vary along the length of the beam. Conditions are found for which both the angle of rotation and the vibrations of the beam may be controlled by applying a force at the free end and a torque at the pivoted end. This is an improvement on previous work of the first author, who showed only that the vibrations may be controlled

The range of the tangential Cauchy-Riemann system on a CR embedded manifold

We prove that every compact, pseudoconvex, orientable, CR manifold of \C^n, bounds a complex manifold in the $C^\infty$ sense. In particular, the tangential Cauchy-Riemann system has closed range