Stefan Edlund

A universal information appliance

The consumers view of a universal information appliance (UIA) is a personal device, such as a PDA (personal digital assistant) or a wearable computer that can interact with any application, access any information store, or remotely operate any electronic device. The technologists view of the UIA is a portable computer, communicating over a bi-directional wireless link to an elaborate software system through which all programs, information stores, and electronic devices can export their interfaces to the UIA. Using an exported interface, the UIA can interoperate with the exporting entity, whether a home security system, a video cassette recorder, corporate application, or an automobile navigation system. Furthermore, interfaces presented by the UIA can be tailored to the users context, such as the users preferences, behavior, and current surroundings. The UIA programming model supports dynamic interface style and content triggered on activity detected from the users real-world and software context. In this paper we describe the design and first implementation of a UIA, a PDA that, through a wireless link, can interact with any program, access any database, or direct most electronic devices through a remote interface. The UIA model uses IBMs TSpaces software package as the interface delivery mechanism and resource database, and as the network communication glue. TSpaces supports communication between the UIA and any peer over a dual-mode wireless link. Using a popular application example, we present a generalized architecture in which the UIA is the mobile users software portal for interoperating with any peer: another UIA, a common network service, a legacy application, or an electronic device.

Perceptual distance and the constancy of size and stereoscopic depth

The relationship between distance and size perception is unclear because of conflicting results of tests investigating the size-distance invariance hypothesis (SDIH), according to which perceived size is proportional to perceived distance. We propose that response bias with regard to measures of perceived distance is at the root of the conflict. Rather than employ the usual method of magnitude estimation, the bias-free two-alternative forced choice (2AFC) method was used to determine the precision (1/sigma) of discriminating depth at different distances. The results led us to define perceptual distance as a bias free power function of physical distance, with an exponent of approximately 0.5. Similar measures involving size differences among stimuli of equal angular size yield the same power function of distance. In addition, size discrimination is noisier than depth discrimination, suggesting that distance information is processed prior to angular size. Size constancy implies that the perceived size is proportional to perceptual distance. Moreover, given a constant relative disparity, depth constancy implies that perceived depth is proportional to the square of perceptual distance. However, the function relating the uncertainties of depth and of size discrimination to distance is the same. Hence, depth and size constancy may be accounted for by the same underlying law.

The effect of antibody-dependent enhancement, cross immunity, and vector population on the dynamics of dengue fever

Dengue is a major international public health concern and impacts one-third of the worlds population. No specific vaccine and treatment are available for this vector-borne disease. There are four similar but distinct serotypes of dengue viruses (DENV). Infection with one serotype affords life-long immunity to that serotype but only temporary partial immunity, or cross immunity (CI), to others. This increases the risk of developing lethal complications upon re-infection, mainly because of the effect of antibody-dependent enhancement (ADE). There have been multiple studies of the dynamic behavior created by the interplay of ADE and CI using mathematical models. However, models in the literature seldom capture the vector population, which we consider important because combating the mosquito vector is the only way to contain dengue transmission in the absence of vaccines. We therefore propose two differential-equation models of dengue fever (DF) with different levels of complexity and details. Our results support the need for ADE to explain the complexity of the epidemiological data.

The spatiotemporal epidemiological modeler

In this paper, we give an overview of the Spatiotemporal Epidemiological Model (STEM), an open source disease modeling application available for free under the Eclipse Public License. We explain why applications such as STEM can benefit from being open and available to the general research community, and describe the design and architecture of STEM, highlighting some of STEMs more important features. Our conclusion cites future plans for the project. A video demonstration of STEM is available at http://www.youtube.com/watch?v=OoiFLemepw4.

A global model of malaria climate sensitivity: comparing malaria response to historic climate data based on simulation and officially reported malaria incidence.

BackgroundThe role of the Anopheles vector in malaria transmission and the effect of climate on Anopheles populations are well established. Models of the impact of climate change on the global malaria burden now have access to high-resolution climate data, but malaria surveillance data tends to be less precise, making model calibration problematic. Measurement of malaria response to fluctuations in climate variables offers a way to address these difficulties. Given the demonstrated sensitivity of malaria transmission to vector capacity, this work tests response functions to fluctuations in land surface temperature and precipitation.MethodsThis study of regional sensitivity of malaria incidence to year-to-year climate variations used an extended Macdonald Ross compartmental disease model (to compute malaria incidence) built on top of a global Anopheles vector capacity model (based on 10 years of satellite climate data). The predicted incidence was compared with estimates from the World Health Organization and the Malaria Atlas. The models and denominator data used are freely available through the Eclipse Foundation’s Spatiotemporal Epidemiological Modeller (STEM).ResultsAlthough the absolute scale factor relating reported malaria to absolute incidence is uncertain, there is a positive correlation between predicted and reported year-to-year variation in malaria burden with an averaged root mean square (RMS) error of 25% comparing normalized incidence across 86 countries. Based on this, the proposed measure of sensitivity of malaria to variations in climate variables indicates locations where malaria is most likely to increase or decrease in response to specific climate factors. Bootstrapping measures the increased uncertainty in predicting malaria sensitivity when reporting is restricted to national level and an annual basis. Results indicate a potential 20x improvement in accuracy if data were available at the level ISO 3166–2 national subdivisions and with monthly time sampling.ConclusionsThe high spatial resolution possible with state-of-the-art numerical models can identify regions most likely to require intervention due to climate changes. Higher-resolution surveillance data can provide a better understanding of how climate fluctuations affect malaria incidence and improve predictions. An open-source modelling framework, such as STEM, can be a valuable tool for the scientific community and provide a collaborative platform for developing such models.

Comparing three basic models for seasonal influenza

In this paper we report the use of the open source Spatiotemporal Epidemiological Modeler (STEM, www.eclipse.org/stem) to compare three basic models for seasonal influenza transmission. The models are designed to test for possible differences between the seasonal transmission of influenza A and B. Model 1 assumes that the seasonality and magnitude of transmission do not vary between influenza A and B. Model 2 assumes that the magnitude of seasonal forcing (i.e., the maximum transmissibility), but not the background transmission or flu season length, differs between influenza A and B. Model 3 assumes that the magnitude of seasonal forcing, the background transmission, and flu season length all differ between strains. The models are all optimized using 10 years of surveillance data from 49 of 50 administrative divisions in Israel. Using a cross-validation technique, we compare the relative accuracy of the models and discuss the potential for prediction. We find that accounting for variation in transmission amplitude increases the predictive ability compared to the base. However, little improvement is obtained by allowing for further variation in the shape of the seasonal forcing function.

Defining the food microbiome for authentication, safety, and process management

Under intense scrutiny for safety and authenticity, our food supply encompasses probiotic supplementation, fermentation organisms, pathogenic bacteria, and microbial toxins—in short, the microbiome and metabolome of food. Recent claims regarding probiotic supplements, additives, and cultured foods highlight the need for widely accepted protocols for evidence-based oversight of such products, as well as specific methods to assess their safety and authenticity. Rapid improvements in high-throughput sequencing technologies, curated and annotated reference databases of whole genome sequences, bacterial strain banks, and novel informatics techniques coupled to a scalable computing platform are poised to provide a robust solution extendable to encompass systematic authentication of the microbiome and its variations up and down the supply chain. Members of the Sequence the Food Supply Chain Consortium are working to characterize and quantify the microbiome at a baseline and after processing. They are also working to create reference databases and develop a Metagenomics Computation and Analytics Workbench, capable of verifying the effectiveness of good manufacturing practices and monitoring control measures highlighted in a sites Hazard Analysis Critical Control Point plan. In this paper, we propose how microbial ecology, evolvability, and phylogenetic diversity exhort the application of new molecular techniques to assure safety, authenticity, and traceability for wholesome food.

Perceptual distance and the moon illusion

The elevated moon usually appears smaller than the horizon moon of equal angular size. This is the moon illusion. Distance cues may enable the perceptual system to place the horizon moon at an effectively greater distance than the elevated moon, thus making it appear as larger. This explanation is related to the size-distance invariance hypothesis. However, the larger horizon moon is usually judged as closer than the smaller zenith moon. A bias to expect an apparently large object to be closer than a smaller object may account for this conflict. We designed experiments to determine if unbiased sensitivity to illusory differences in the size and distance of the moon (as measured by d ′) is consistent with SDIH. A moon above a ‘terrain’ was compared in both distance and size to an infinitely distant moon in empty space (the reduction moon). At a short distance the terrain moon was adjudged as both closer and smaller than the reduction moon. But these differences could not be detected at somewhat greater distances. At still greater distances the terrain moon was perceived as both more distant and larger than the reduction moon. The distances at which these transitions occurred were essentially the same for both distance and size discrimination tasks, thus supporting SDIH.

Infectious Disease Modeling: Creating a Community to Respond to Biological Threats

The rise of global economies in the 21st century, the rapid national and international movement of people, and the increased reliance of developed countries on global trade, all greatly increase the potential and possible magnitude of a worldwide pandemic. New epidemics may be the result of global climate change, vector-borne diseases, food-borne illness, new naturally occurring pathogens, or bio-terrorist attacks. The threat is most severe for highly communicable diseases. When rapidly spreading microparasitic infections coincide with the rapid transportation, propagation, and dissemination of the pathogens and vectors for infection, the risks associated with emerging infectious disease increase. We discuss the use of publicly-available technologies in assisting public health officials and scientists in protecting populations from emerging disease or in implementing improved response measures. We illustrate possibilities using the SpatioTemporal Epidemiological Modeler (STEM) that was developed to run on the Open Health Framework (OHF) created by the Eclipse Foundation in 2004. An illustration regarding the spread of the influenza H1N1 virus from Mexico to the United States via air travel in Spring 2009 is briefly discussed.

The Social Contract Core

The information age has brought with it the promise of unprecedented economic growth based on the efficiencies made possible by new technology. This same greater efficiency has left society with less and less time to adapt to technological progress. Perhaps the greatest cost of this progress is the threat to privacy we all face from unconstrained exchange of our personal information. In response to this threat, the World Wide Web Consortium has introduced the “Platform for Privacy Preferences” (P3P) to allow sites to express policies in machine-readable form and to expose these policies to site visitors [Cranor et al., 8]. However, today P3P does not protect the privacy of individuals, nor does its implementation empower communities or groups to negotiate and establish standards of behavior. It is only through such negotiation or feedback that new social contracts can evolve. We propose a privacy architecture, the Social Contract Core (SCC), designed to use technology to facilitate this feedback and so speed the establishment of new “Social Contracts” needed to protect private data. The goal of SCC is to empower communities, speed the “socialization” of new technology, and encourage the rapid access to, and exchange of, information. Addressing these issues is essential, we feel, to both liberty and economic prosperity in the information age [Kaufman et al., 17].