This paper aims to study the effects of wind-driven rain load and vapor diffusion on the hygrothermal performance of wall systems in a wet and mild climate through a field experimental study. In the study, four test panels with a combination of vapor barrier and capillary break are manufactured, instrumented and installed in a field experimental facility. The wetting and drying potentials of the test panels in response to a predominately vapor diffusion and a wind-driven rain load are discussed based on the analysis of 15 months of measurement data. The experimental result shows that, in a yearly basis, the wetting and drying rates of a wall without a capillary break are about two times higher than that of the wall with a capillary break. While the wetting and drying rates are comparable in a wall system with a vapor barrier, the drying rate is 38% higher than the wetting rate in a wall with no vapor barrier. In general, a wall with no vapor barrier wets and also dries faster than a wall with a vapor barrier. For the wall types and climate considered in this paper, the wetting rates of walls with a predominately wetting mechanism of vapor diffusion and wind-drive rain load are comparable. In general, the experimental data suggest that even in a mild climate, vapor diffusion is a critical moisture load with comparable effect that wind-driven load induces., Peer-reviewed article, Published. Received 14 February 2015, Revised 10 May 2015, Accepted 11 May 2015, Available online 19 May 2015.
Recently, the amount of dredged soil material (DM) has been rapidly increasing in Korea due to four major river maintenance projects and new harbor construction. DM waste is mostly dumped into the ocean, while only a small part of it has been utilized for coastal reclaiming, or as filling and backfilling material. This study carried out physical and chemical tests to map out a specific plan for utilizing DM in a mortar mixture. The compressive strength tests and microstructure analysis using XRD and SEM of cement mortar contained DM were performed as a replacement for fine aggregate or as a filler material of mortar matrix. The study measured the impact of contaminants contained in DM and how silt and clay influenced the compressive strength of the mortar., Peer-reviewed article, Published. Received April 7th, 2011; revised May 16th, 2011; accepted June 1st, 2011.
Proceedings of the 8th International Symposium on Logical Formalizations of Commonsense Reasoning. Stanford, CA, 2007. Cryptographic protocols are structured sequences of messages that are used for exchanging information in a hostile environment. Many protocols have epistemic goals: a successful run of the protocol is intended to cause a participant to hold certain beliefs. As such, epistemic logics have been employed for the verification of cryptographic protocols. Although this approach to verification is explicitly concerned with changing beliefs, formal belief change operators have not been incorporated in previous work. In this preliminary paper, we introduce a new approach to protocol verification by combining a monotonic logic with a non-monotonic belief change operator. In this context, a protocol participant is able to retract beliefs in response to new information and a protocol participant is able to postulate the most plausible event explaining new information. Hence, protocol participants may draw conclusions from received messages in the same manner conclusions are drawn in formalizations of commonsense reasoning. We illustrate that this kind of reasoning is particularly important when protocol participants have incorrect beliefs., Conference paper, Published.
Proceedings of 2016 14th Annual Conference on Privacy, Security and Trust (PST) in Auckland, New Zealand, 12-14 Dec. 2016. We address security vulnerabilities for a smart thermostat. As this kind of smart appliance is adopted in homes around the world, every user will be opening up a new avenue for cyber attack. Since these devices have known vulnerabilities and they are being managed by non-technical users, we anticipate that smart thermostats are likely to be targetted by unsophisticated attackers relying on publicly available exploits to take advantage of weakly protected devices. As such, in this paper, we take the role of a `script kiddy' and we assess the security of a smart thermostat by using Internet resources for attacks at both the physical level and the network level. We demonstrate that such attacks are unlikely to be effective without some additional social engineering to obtain user credentials. Moreover, we suggest that the vulnerability to attack can be further minimized by simply reducing the use of remote storage where possible., Conference paper
Proceedings of the AAAI Workshop on Artificial Intelligence for Cities, Austin, USA, 2015. The Smart Grid allows users to monitor power usage through the use of Smart Meter technology. In principle, this information can be used to modify usage habits in a way that reduces consumer costs as well as greenhouse emissions. However, in an urban environment, many users are restricted by the same constaints: they work during the day, and they are home at night. This creates spikes in power cost at peak usage times, and it may also lead to increased emissions in scenarios where sustainable resources are limited. An individual user can avoid these spikes by using an electric car as a storage device; it can be charged at the cheapest times, and then discharged to the home at the most expensive times. While this idea is intuitively appealing, it turns out that the benefits vary greatly depending on the storage algorithm used. In this paper, we describe the Power Storage Simulator, a tool for experimenting with storage algorithms to improve the efficiency of vehicle to grid systems. We suggest that this tool is also useful for educating power consumers about load balancing on the Smart Grid through an engaging, visual simulation., Conference paper, Published.
Background Previous evidence suggests the effects of task-specific therapy can be further enhanced when sensory stimulation is combined with motor practice. Sensory tongue stimulation is thought to facilitate activation of regions in the brain that are important for balance and gait. Improvements in balance and gait have significant implications for functional mobility for people with incomplete spinal cord injury (iSCI). The aim of this case study was to evaluate the feasibility of a lab- and home-based program combining sensory tongue stimulation with balance and gait training on functional outcomes in people with iSCI. Methods Two male participants (S1 and S2) with chronic motor iSCI completed 12 weeks of balance and gait training (3 lab and 2 home based sessions per week) combined with sensory tongue stimulation using the Portable Neuromodulation Stimulator (PoNS). Laboratory based training involved 20 minutes of standing balance with eyes closed and 30 minutes of body-weight support treadmill walking. Home based sessions consisted of balancing with eyes open and walking with parallel bars or a walker for up to 20 minutes each. Subjects continued daily at-home training for an additional 12 weeks as follow-up. Results Both subjects were able to complete a minimum of 83% of the training sessions. Standing balance with eyes closed increased from 0.2 to 4.0 minutes and 0.0 to 0.2 minutes for S1 and S2, respectively. Balance confidence also improved at follow-up after the home-based program. Over ground walking speed improved by 0.14 m/s for S1 and 0.07 m/s for S2, and skilled walking function improved by 60% and 21% for S1 and S2, respectively. Conclusions Sensory tongue stimulation combined with task-specific training may be a feasible method for improving balance and gait in people with iSCI. Our findings warrant further controlled studies to determine the added benefits of sensory tongue stimulation to rehabilitation training., Peer-reviewed article, Published. Received: 10 July 2013 ; Accepted: 2 June 2014 ; Published: 6 June 2014.
The in vivo application of appropriate trophic factors may enhance regeneration of bulbospinal projections after spinal cord injury. Currently, little is known about the sensitivities of specific bulbospinal neuron populations to the many identified trophic factors. We devised novel in vitro assays to study trophic effects on the survival and neurite outgrowth of identified bulbospinal neurons. Carbocyanine dye crystals implanted into the cervical spinal cord of embryonic day (E)5 chick embryos retrogradely labeled developing bulbospinal neurons. On E8, dissociated cultures containing labeled bulbospinal neurons were prepared. Fibroblast growth factor (FGF)-2 (but not FGF-1) promoted the survival of bulbospinal neurons. FGF receptor expression was widespread in the E8 brainstem, but not detected in young bulbospinal neurons, suggesting that nonneuronal cells mediated the FGF-stimulated survival response. Astrocytes synthesize a variety of trophic factors, and astrocyte-conditioned medium (ACM) also promoted the survival of bulbospinal neurons. As might be expected, FGF-2 function blocking antibodies did not suppress ACM-promoted survival, nor did an ELISA detect FGF-2 in ACM. This suggests that nonneuronal cells synthesize other factors in response to exogenous FGF-2 which promote the survival of bulbospinal neurons. Focusing on vestibulospinal neurons, dissociated (survival assay) or explant (neurite outgrowth assay) cultures were prepared. FGF-2 promoted both survival and neurite outgrowth of identified vestibulospinal neurons. Interestingly, FGF-1 promoted neurite outgrowth but not survival; the converse was true of FGF-9. Thus, differential effects of specific growth factors on survival or neurite outgrowth of bulbospinal neurons were distinguished., Peer-reviewed article, Published. Received 10 September 1999; Accepted 18 January 2000; Available online 25 May 2002.
The functional level (K level) of prosthetic users is used to choose appropriate prosthetic components, but ratings may highly subjective. A more objective and robust method to determine K level may be appealing. The aim of this study was to determine the relationship between K level determined in the clinic to K level based on real world ambulatory activity data collected by StepWatch. Twelve individuals with transtibial limb loss gave informed consent to participate. K level assessments performed in the clinic by a single treating prosthetist were compared with a calculated estimate based on seven days of real world ambulatory activity patterns using linear regression. There was good agreement between the two methods of determining K level with R2 = 0.775 (p < 0.001). The calculated estimate of K level based on actual ambulatory activity in real world settings appears to be similar to the treating prosthetist’s assessment of K level based on gait observation and patient responses in the clinic. Clinic-based ambulatory capacity in transtibial prosthetic users appears to correlate with real world ambulatory behavior in this small cohort. Determining functional level based on real world ambulatory activity may supplement clinic-based tests of functional capacity., Peer-reviewed article, Published. Date received: 2 December 2015; Accepted: 20 January 2016; First Published March 9, 2016.
Describes research work directed towards the development and application of a design methodology to determine the optimal configuration of a powered upper-limb orthosis. The design objective was to minimize the orthosis complexity, defined as the number of degrees of freedom, while maintaining the ability to perform specific tasks. This objective was achieved in three stages. First, potential users of a powered orthosis were interviewed to determine their priority tasks. Secondly, the natural arm motions of able-bodied individuals performing the priority tasks were profiled using a video tracking system. Finally, a kinematic simulation algorithm was developed and employed in order to evaluate whether a proposed orthosis configuration could perform the priority tasks. The research results indicate that task functionality is overly compromised for orthosis configurations with less than five degrees of freedom, plus prehension. Acceptable task performance, based on the specific priority tasks considered, was achieved in the simulations of two different orthosis configurations with five degrees of freedom. In the first design option, elevation (rotation about a horizontal axis through the shoulder) and radial/ulnar deviation are fixed, while in the second option wrist flexion and radial/ulnar deviation are fixed. A prototype orthosis is currently being developed using the first design option., Peer-reviewed article, Published.
Proceedings of 2011 21st International Conference on Noise and Fluctuations in Toronto, ON, Canada on 12-16 June 2011. Fruit flies serve as a model for understanding the genetic regulation involved in specifying the complex body plans of higher animals. The head-to-tail (anterior-posterior) axis of the fly (Drosophila) is established in the first hours of development. Maternally supplied factors form concentration gradients which direct embryonic (zygotic) genes where to be activated to express proteins. These protein patterns specify the positions and cell types of the body's tissues. Recent research has shown, comparing between embryos, that the zygotic gene products are much more precisely positioned than the maternal gradients, indicating an embryonic error reduction mechanism. Within embryos, there is the additional aspect that DNA and mRNA operate at very low copy number, and the associated high relative noise has the potential to strongly affect protein expression patterns. In recent work, we have focused on the noise aspects of positional specification within individual embryos. We simulate activation of hunchback (hb), a primary target of the maternal Bicoid (Bcd) protein gradient, which forms an expression pattern dividing the embryo into anterior and posterior halves. We use a master equation approach to simulate the stochastic dynamics of hb regulation, using the known details of the hb promoter, the region of DNA responsible for transcribing hb mRNA. This includes the binding/unbinding of Bcd molecules at the promoter, hb transcription, subsequent translation to Hb protein, binding/unbinding of Hb at the promoter (self-regulation), and diffusion of the Bcd and Hb proteins. Model parameters were set by deterministically matching large scale pattern features for a series of experimental expression patterns: wild-type (WT) embryos; hb mutants lacking self-regulation; and constructs in which portions of the hb promoter were used to express a reporter gene (lacZ). The model was then solved stochastically to predict the noise output in these different experiments. In subsequent noise measurements we experimentally corroborated a number of the predictions. These include that mRNA is noisier than protein, and that Hb self-regulation reduces noise. Results indicate that WT (self-regulatory) Hb output noise is predominantly dependent on the transcription and translation dynamics of its own expression, and is uncorrelated with Bcd fluctuations. This contradicts prior work, which had assumed a complete dependence of Hb fluctuations on Bcd fluctuations. In the constructs and mutant, which lack self-regulation, we find that increasing the number and strength of Bcd binding sites (there are 6 in the core hb promoter) provides a rudimentary level of noise reduction. The model is robust to the various Bcd binding site numbers seen across different fly species. New directions in the project include incorporating a known inhibitor of hb, Krüppel, into the model to study its effect on the noise dynamics. Our study has identified particular ways in which hb output noise is controlled. Since these involve common modes of gene regulation (e.g. multiple regulatory sites, self-regulation), these results contribute to the general understanding of the reproducibility and determinacy of spatial patterning in early development., Conference paper, Published.
Positional information in developing embryos is specified by spatial gradients of transcriptional regulators. One of the classic systems for studying this is the activation of the hunchback (hb) gene in early fruit fly (Drosophila) segmentation by the maternally-derived gradient of the Bicoid (Bcd) protein. Gene regulation is subject to intrinsic noise which can produce variable expression. This variability must be constrained in the highly reproducible and coordinated events of development. We identify means by which noise is controlled during gene expression by characterizing the dependence of hb mRNA and protein output noise on hb promoter structure and transcriptional dynamics. We use a stochastic model of the hb promoter in which the number and strength of Bcd and Hb (self-regulatory) binding sites can be varied. Model parameters are fit to data from WT embryos, the self-regulation mutant hb(14F), and lacZ reporter constructs using different portions of the hb promoter. We have corroborated model noise predictions experimentally. The results indicate that WT (self-regulatory) Hb output noise is predominantly dependent on the transcription and translation dynamics of its own expression, rather than on Bcd fluctuations. The constructs and mutant, which lack self-regulation, indicate that the multiple Bcd binding sites in the hb promoter (and their strengths) also play a role in buffering noise. The model is robust to the variation in Bcd binding site number across a number of fly species. This study identifies particular ways in which promoter structure and regulatory dynamics reduce hb output noise. Insofar as many of these are common features of genes (e.g. multiple regulatory sites, cooperativity, self-feedback), the current results contribute to the general understanding of the reproducibility and determinacy of spatial patterning in early development., Peer-reviewed article, Publisher. Received July 4, 2010; Accepted December 28, 2010; Published February 3, 2011.