On large deviation regimes for random media models

The focus of this article is on the different behavior of large deviations of random subadditive functionals above the mean versus large deviations below the mean in two random media models. We consider the point-to-point first passage percolation time $a_n$ on $\mathbb{Z}^d$ and a last passage percolation time $Z_n$. For these functionals, we have $\lim_{n\to\infty}\frac{a_n}{n}=\nu$ and $\lim_{n\to\infty}\frac{Z_n}{n}=\mu$. Typically, the large deviations for such functionals exhibits a strong asymmetry, large deviations above the limiting value are radically different from large deviations below this quantity. We develop robust techniques to quantify and explain the differences.Comment: Published in at http://dx.doi.org/10.1214/08-AAP535 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

What are people's responses to thermal discomfort? Sensing clothing and activity levels using senseCam

Recent international agreements on reducing energy consumption have led to a series of interventions in residential buildings, from modifying the building fabric to upgrading operating systems. To date, these attempts have met with limited success. One reason for this has been identified as the ‘rebound effect’, where the occupants’ respond to their home thermal environment change in unexpected ways after interventions. Often people decide to turn up the heating, to leave it on for longer, or to increase the average spatial temperature by heating more rooms. Although much of the research on heating patterns in dwellings has focused on identifying methods to predict and to assess thermal sensation, less is understood about the way occupants form their responses. Research presented in this paper focuses on mapping householders thermal discomfort responses. Empirical methods, drawn from the social and cognitive sciences, were used in a several studies, which monitored a small sample of UK households during winter of 2010. One of the tools used, the SenseCam, facilitates an automatic electronic diary collection by logging occupants’ responses in a systematic approach.SenseCam results enabled the mapping of participants’ activities in their home, in particular the estimation of clothing and activity level throughout the record period. The preliminary monitoring results show that different householders are interacting with their home thermal comfort systems in very different ways, and that their responses diverge from the current predictive models. Further analysisexamines the factors influencing responses to thermal discomfort and thereby energy consumption of individual in dwellings

The role of environmental and personal variables in influencing thermal comfort indices used in building simulation

The need to identify variables, which influence human behaviour, has become one of the priorities in the quest to reduce energy demand. Environmental and personal variables, as set out in the thermal comfort models, have long been associated with people’s behaviour by predicting their state of thermal comfort or rather discomfort. The aim of this paper is to explore and to report on the influences of these variables on thermal discomfort indices used in building simulation models. Surprisingly, the results of the sensitivity analysis show that different indices are most sensitive to different variables

Understanding the dynamics of residential energy consumption in the UK: mapping occupants thermal discomfort responses

Attempts to reduce the energy consumed in UK homes have had limited success. One reason for this has been identified as the ‘rebound effect’, where the occupants’ responses to their thermal environment change in unexpected ways after interventions. Although much of the research on heating patterns in dwellings has focused on achieving thermal comfort, less is understood about the way occupants form their responses. Using empirical methods drawn from social and cognitive sciences, this paper proposes a set of tools, implemented in a pilot study, carried out on a small sample of UK households during winter of 2010. One of the tools used, the SenseCam facilitates an electronic diary collection by logging occupants’ responses in a systematic approach. Preliminary monitoring works show that different householders are interacting with their home thermal comfort systems in very different ways, and that their responses diverge from the current predictive models. These results suggest that future samples may be examined to gain further insights about the development of ideas in this field

Subwavelength position sensing using nonlinear feedback and wave chaos

We demonstrate a position-sensing technique that relies on the inherent sensitivity of chaos, where we illuminate a subwavelength object with a complex structured radio-frequency field generated using wave chaos and a nonlinear feedback loop. We operate the system in a quasi-periodic state and analyze changes in the frequency content of the scalar voltage signal in the feedback loop. This allows us to extract the object's position with a one-dimensional resolution of ~\lambda/10,000 and a two-dimensional resolution of ~\lambda/300, where \lambda\ is the shortest wavelength of the illuminating source.Comment: 4 pages, 4 figure

A Kaluza-Klein Model with Spontaneous Symmetry Breaking: Light-Particle Effective Action and its Compactification Scale Dependence

We investigate decoupling of heavy Kaluza-Klein modes in an Abelian Higgs model with space-time topologies $\mathbb{R}^{3,1} \times S^{1}$ and $\mathbb{R}^{3,1} \times S^{1}/\mathbb{Z}_{2}$. After integrating out heavy KK modes we find the effective action for the zero mode fields. We find that in the $\mathbb{R}^{3,1} \times S^{1}$ topology the heavy modes do not decouple in the effective action, due to the zero mode of the 5-th component of the 5-d gauge field $A_{5}$. Because $A_{5}$ is a scalar under 4-d Lorentz transformations, there is no gauge symmetry protecting it from getting mass and $A_{5}^{4}$ interaction terms after loop corrections. In addition, after symmetry breaking, we find new divergences in the $A_{5}$ mass that did not appear in the symmetric phase. The new divergences are traced back to the gauge-goldstone mixing that occurs after symmetry breaking. The relevance of these new divergences to Symanzik's theorem is discussed. In order to get a more sensible theory we investigate the $S^{1}/\mathbb{Z}_{2}$ compactification. With this kind of compact topology, the $A_{5}$ zero mode disappears. With no $A_{5}$, there are no new divergences and the heavy modes decouple. We also discuss the dependence of the couplings and masses on the compactification scale. We derive a set of RG-like equations for the running of the effective couplings with respect to the compactification scale. It is found that magnitudes of both couplings decrease as the scale $M$ increases. The effective masses are also shown to decrease with increasing compactification scale. All of this opens up the possibility of placing constraints on the size of extra dimensions.Comment: 35 pages, 6 figure