Yeung Lam

Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California

Abstract Within alpine environments the interactions of air temperature, solar irradiance, wind, surface albedo, microtopography, and biotic traits all influence patterns of soil and plant canopy temperatures. The resulting mosaic of surface temperatures has a profound impact on ecosystem processes, plant survival, and ecophysiological performance. Previous studies have documented large and persistent variations in microhabitat temperatures over mesoscale alpine terrains. We have used a novel mobile system to examine changes in soil and plant canopy surface temperatures at spatial scales of centimeters and temporal scales of minutes in an alpine fellfield habitat in the White Mountains of California. In the middle of a summer day, the mean surface temperature differences between points 2, 5, and 10 cm apart were 2.9, 5.4, and 9.0 °C, respectively, and extreme differences of 18 °C or more were found over distances of a few centimeters. These thermal patterns are due not only to substrate material but also to biotic conditions of plant canopy architecture and ecophysiological traits of individual species. The magnitude of temperature variation at these fine scales is greater than the range of warming scenarios in Intergovernmental Panel on Climate Change (IPCC) projections, suggesting that these habitats offer the capacity of significant thermal heterogeneity for plant survival.

Human Assisted Robotic Team Campaigns for Aquatic Monitoring

Large-scale environmental sensing, e.g., understanding microbial processes in an aquatic ecosystem, requires coordination across a multidisciplinary team of experts working closely with a robotic sensing and sampling system. We describe a human-robot team that conducted an aquatic sampling campaign in Lake Fulmor, San Jacinto Mountains Reserve, California during three consecutive site visits (May 9–11, June 19–22, and August 28–31, 2006). The goal of the campaign was to study the behavior of phytoplankton in the lake and their relationship to the underlying physical, chemical, and biological parameters. Phytoplankton form the largest source of oxygen and the foundation of the food web in most aquatic ecosystems. The reported campaign consisted of three system deployments spanning four months. The robotic system consisted of two subsystems—NAMOS (networked aquatic microbial observing systems) comprised of a robotic boat and static buoys, and NIMS-RD (rapidly deployable networked infomechanical systems) comprised of an infrastructure-supported tethered robotic system capable of high-resolution sampling in a two-dimensional cross section (vertical plane) of the lake. The multidisciplinary human team consisted of 25 investigators from robotics, computer science, engineering, biology, and statistics.We describe the lake profiling campaign requirements, the robotic systems assisted by a human team to perform high fidelity sampling, and the sensing devices used during the campaign to observe several environmental parameters. We discuss measures taken to ensure system robustness and quality of the collected data. Finally, we present an analysis of the data collected by iteratively adapting our experiment design to the observations in the sampled environment. We conclude with the plans for future deployments.

A wireless biomedical handheld instrument for evidence-based detection of pressure ulcers

Pressure Ulcer (PU) incidence leads to considerable risk, in particular for the frail elderly, and a large national healthcare treatment cost. Evidence-based methods for assuring the health and safety of patients are urgently needed. Recent clinical trials have demonstrated that sub-epidermal moisture (SEM) present in tissue may be measured by interrogation of tissue dielectric properties and are associated with the presence of erythema and development of early stage PU conditions. A novel wireless handheld device has been developed and will be demonstrated that introduces a series of advances including automated measurement, automated measurement method assurance including application of proper measurement applied pressure, and wireless energy recharge capability. This advances previous successful prototype development to now include a complete point-of-care usage product. This device, termed the SEM Scanner, was successfully verified in trials with 30 subjects and is currently deployed in large clinical trials in nursing homes in Los Angeles. This manuscript and the planned demonstration describe a set of significant technology advances over previous technology based on both new Wireless Health hardware and software system solutions. In addition to the demonstration to be provided of a novel end-to-end system including data acquisition, data archiving, reporting, and compliance verification, data from trials will also be presented.

Wearable sensor for continuously vigilant spatial and depth-resolved perfusion imaging

Direct characterization of blood perfusion in tissue is critical to a broad spectrum of applications in assessing circulatory disorders, wound conditions and ensuring outcomes of treatment. The rapid evolution of these conditions and their great risk for subjects require a continuously vigilant monitoring technology. This paper presents a wireless health platform providing the first wearable blood perfusion imager. This system, the Perfusion Oxygenation Monitor (POM), introduces sensing diversity by combining array methods and multispectral methods, as well as sensor and emitter distribution and operation scheduling. The principles of photoplethysmographic (PPG) sensing exploited by new methods will enable care providers to actively monitor blood perfusion at multiple anatomical sites for characterization and tracking of perfusion critical to tissue health, wound status and healing, formation of pressure ulcers, and circulation conditions. The POM system is described here along with its experimental validation. Experimental validation has been provided by a direct probing method based on physiological thermoregulatory response that induces perfusion change and is directly measured by POM. The demonstration of the POM system will also be supplemented by an analysis of the end to end system including sensor information processing, feature detection, Wireless Health data transport, and archive structure.