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PubMed1998

Online evolution for a self-adapting robotic navigation system using evolvable hardware.

Great interest has been shown in the application of the principles of artificial life to physically embedded systems such as mobile robots, computer networks, home devices able continuously and autonomously to adapt their behavior to changes of the environments. At the same time researchers have been working on the development of evolvable hardware, and new integrated circuits that are able to adapt their hardware autonomously and in real time in a changing environment. This article describes the navigation task for a real mobile robot and its implementation on evolvable hardware. The robot must track a colored ball, while avoiding obstacles in an environment that is unknown and dynamic. Although a model-free evolution method is not feasible for real-world applications due to the sheer number of possible interactions with the environment, we show that a model-based evolution can reduce these interactions by two orders of magnitude, even when some of the robot's sensors are blinded, thus allowing us to apply evolutionary processes online to obtain a self-adaptive tracking system in the real world, when the implementation is accelerated by the utilization of evolvable hardware.

Biological Evolution↗

PubMed2006

Poultry litter application to loblolly pine forests: growth and nutrient containment.

Forestland application of poultry manure offers an alternative to the conventional practice of pastureland application. Before such a practice is considered viable, however, it must be demonstrated that the forest ecosystem is capable of absorbing the nutrients contained in poultry manure, especially nitrogen (N) and phosphorus (P). From the forestry perspective, it must also be demonstrated that tree growth is not diminished. We investigated these questions using loblolly pine (Pinus taeda L.) stands growing in central Mississippi in an area of high poultry production. Stockpiled broiler litter was applied to newly thinned, 8-yr-old stands at 0, 4.6, and 18.6 dry Mg ha-1, supplying 0, 200, and 800 kg N ha-1 and 0, 92, and 370 kg P ha-1, respectively. Levels of nitrate in soil water, monitored at a 50-cm depth with porous cup tension lysimeters, exceeded 10 mg N L-1 during the first two years after application in the 18.6 Mg ha-1 rate but only on two occasions in the first year for the lower rate of application. Phosphate was largely absent from lysimeter water in all treatments. Other macronutrients (K, Ca, Mg, S) were elevated in lysimeter water in proportion to litter application rates. Soil extractable nitrate showed similar trends to lysimeter water, with substantial elevation during the first year following application for the 18.6 Mg ha-1 rate. Mehlich III-extractable phosphate peaked in excess of 100 microg P g-1 soil during the third year of the study for the 18.6 Mg ha-1 rate. The 4.6 Mg ha-1 rate did not affect extractable soil P. Tree growth was increased by the poultry litter. Total stem cross-sectional area, or basal area, was approximately 20% greater after 2 yr for both rates of litter application. Overall, the nutrients supplied by the 4.6 Mg ha-1 rate were contained by the pine forest and resulted in favorable increases in tree growth. The higher rate, by contrast, did pose some risk to water quality through the mobilization of nitrate. These results show that, under the conditions of this study, application of poultry litter at moderate rates of approximately 5 Mg ha-1 to young stands of loblolly pine offers an alternative disposal option with minimal impacts to water quality and potential increases in tree growth.

Animals↗

PubMed2005

Structure/transport relationships in silver-based oxide glasses: 1-D and 2-D NMR information.

AgI-doped silver oxide glasses are of interest both for their possible applications in electrochemical devices, and as a model system to study the transport/structure relationships in ionic glasses. Here we summarize the information given by 1-D and 2-D solid-state NMR measurements on both the cations dynamics and short (and medium) range structure of several glassy systems. Emphasis is given to understand how AgI enters into the glass matrix. A new and careful analysis of our previously reported 109Ag 1-D data shows that the glass matrix plays a relevant role in determining the efficiency of carriers formation, as well as their mobility. Finally, as an example of a modern 2-D NMR application to these materials, we report the first 11B and 17O Multiple Quantum MAS study on a glass of the system AgI:Ag2O:2B2O2, which confirms the nearly complete absence of non-bridging oxygens (NBOs) in the silver diborate composition.

Journal Article↗

PubMed1998

Easy Medic: an Internet application for the general practitioner.

A research project has been carried out to develop a client server application which supplies the general practitioner (GP) with a 'personal digital assistant' (hand-held mobile computer) to connect to Web servers at a hospital site through the Internet. This allows the doctor to book medical examinations, hospital admissions and manage patient data. The application used advanced object-oriented techniques, on both the client and the server side. The connection to a Web server was achieved through GSM wireless cellular telephones using standard Internet protocols (HTTP, TCP/IP and CGI). Conventional telephone lines can be used as well. Other application modules on the client side provided patients medical record supervision, GP schedule management, general information about hospitals and clinics, and pharmacy consultation. These services should help GPs in their daily work. Moreover, the quality of health-care resource management and cost supervision should improve, since each GP 'transaction' is automatically entered in realtime into a database at the server. The services are under test in the health-care system of an urban area in southern Italy.

Computer Communication Networks↗

PubMed2002

Paradoxical motion of a single Brownian particle: absolute negative mobility.

We consider a single, classical Brownian particle in a spatially symmetric periodic system far from thermal equilibrium, which can be readily realized experimentally. Upon application of an external static force F, the average particle velocity is negative for F>0 and positive for F<0 (absolute negative mobility). The various physical mechanisms responsible for such a paradoxical effect are identified, leading to analytical approximations that are in good agreement with numerical simulations.

Journal Article↗

PubMed2002

Brownian motion exhibiting absolute negative mobility.

We consider a single Brownian particle in a spatially symmetric, periodic system far from thermal equilibrium. This setup can be readily realized experimentally. Upon application of an external static force F, the average particle velocity is negative for F>0 and positive for F<0 (absolute negative mobility).

Journal Article↗

PubMed1997

The forms of knowledge mobilized in some machine vision systems.

This paper describes a number of computer vision systems that we have constructed, and which are firmly based on knowledge of diverse sorts. However, that knowledge is often represented in a way that is only accessible to a limited set of processes, that make limited use of it, and though the knowledge is amenable to change, in practice it can only be changed in rather simple ways. The rest of the paper addresses the questions: (i) what knowledge is mobilized in the furtherance of a perceptual task?; (ii) how is that knowledge represented?; and (iii) how is that knowledge mobilized? First we review some cases of early visual processing where the mobilization of knowledge seems to be a key contributor to success yet where the knowledge is deliberately represented in a quite inflexible way. After considering the knowledge that is involved in overcoming the projective nature of images, we move the discussion to the knowledge that was required in programs to match, register, and recognize shapes in a range of applications. Finally, we discuss the current state of process architectures for knowledge mobilization.

Humans↗

PubMed2005

Virtual reality and computer-enhanced training applied to wheeled mobility: an overview of work in Pittsburgh.

Some aspects of assistive technology can be enhanced by the application of virtual reality. Although virtual simulation offers a range of new possibilities, learning to navigate in a virtual environment is not equivalent to learning to navigate in the real world. Therefore, virtual reality simulation is advocated as a useful preparation for assessment and training within the physical environment. We are engaged in several efforts to develop virtual environments and devices for mobility skills assessment and training, exercise training, and environment assessment. Virtual reality offers wheelchair users a training tool in different risk-free environments without any indoor (e.g., walls, furniture, and stairs) and outdoor (e.g., curb cuts, uneven terrain, and street traffic) physical constraints. Virtual reality technology will probably become more common in the field of assistive technology, especially given the rapid expansion of gaming technology and the continued exponential growth of computing power.

Computer Simulation↗

PubMed2006

Multispectral imaging of ion transport in neutral carrier-based cation-selective membranes.

BACKGROUND: High-resolution spectroscopic imaging of the cross section of ion-selective membranes during real-time electrochemical measurements is termed spectroelectrochemical microscopy (SpECM). SpECM is aimed for optimizing the experimental conditions in mass transport controlled ion-selective electrode (ISE) membranes for improved detection limit. METHODS: The SpECM measurements are performed in a thin layer electrochemical cell. The key element of the cell is a membrane strip spacer ring assembly which forms a two compartment electrochemical cell. The cell is placed onto the stage of a microscope and the membrane strip is positioned in the center of the field of view. A slice of the image is focused onto the entrance slit of the imaging spectrometer. RESULTS: SpECM has been used for the determination of the diffusion coefficients of different membrane ingredients and for the quantitative assessment of the charged site concentrations in ISE membranes and membrane plasticizers. In addition, changes in the concentration profiles of the ionophore (free and complexed) and charged mobile sites inside the ISE membranes are documented upon the application of large external voltages. CONCLUSIONS: This account demonstrates the power and advantages of SpECM, a multispectral imaging method for investigations of mass transport processes in ISE membranes during electrochemical measurements.

Cations↗

PubMed1997

Sulfobutylether-beta-cyclodextrin-mediated capillary electrophoresis for separation of chlorinated and substituted phenols.

Cyclodextrin-mediated capillary electrophoresis has been developed for separation and analysis of chlorinated as well as substituted phenolic compounds. The procedure used a negatively charged sulfobutylether-beta-cyclodextrin (SB-betaCD) to effect differential partitioning of the phenols between the buffer and CD phases. In 50 mM phosphate buffer containing as low as 1 mM SB-betaCD, 25 phenolic compounds including 11 Environmental Protection Agency (EPA) priority phenols were separated with theoretical plate numbers well above 100,000, for 50 cm of effective length in most cases. An equilibrium complexation model was used for investigating the effect of pH as well as different cyclodextrin concentrations on the electrophoretic mobility. The cyclodextrin-mediated capillary electrophoresis system was also applicable for separating and quantifying the level of pentachlorophenol in contaminated soil samples.

Chlorophenols↗

PubMed2003

A family of single-isomer, sulfated gamma-cyclodextrin chiral resolving agents for capillary electrophoresis: octa(6-O-sulfo)-gamma-cyclodextrin.

The second member of the single-isomer, sulfated gamma-cyclodextrin family, the sodium salt of octa(6-O-sulfo)-gamma-cyclodextrin (OS) has been synthesized, characterized and used to separate the enantiomers of nonelectrolyte, acidic, basic, and ampholytic analytes by capillary electrophoresis in acidic aqueous background electrolytes. The anionic effective mobilities of the nonelectrolyte and anionic analytes increased with increasing concentration of OS. The effective mobilities of strongly complexing cationic analytes became anionic with very low OS concentrations and passed local anionic effective mobility maxima as the OS concentration, and along with it, the ionic strength, of the background electrolyte increased. The effective mobilities of the weakly binding cationic analytes became only slightly anionic at high OS concentration values and did not show the local anionic effective mobility maxima. For nonelectrolyte analytes, separation selectivities decreased with increasing OS concentration. For cationic analytes, separation selectivities were highest where the effective mobilities of the less mobile enantiomers approached zero. OS proved to be a broadly applicable chiral resolving agent.

Cyclodextrins↗

PubMed2004

Mobile, outdoor continuous-flow isotope-ratio mass spectrometer system for automated high-frequency 13C- and 18O-CO2 analysis for Keeling plot applications.

A continuous-flow isotope-ratio mass spectrometer (CF-IRMS, custom-made GasBenchII and Delta(plus)Advantage, ThermoFinnigan) was installed on a grassland site and interfaced with a closed-path infrared gas analyser (IRGA). The CF-IRMS and IRGA were housed in an air-conditioned travel van. Air was sampled at 1.5 m above the 0.07-m tall grassland canopy, drawn through a 17-m long PTFE tube at a rate of 0.25 L s(-1), and fed to the IRGA and CF-IRMS in series. The IRMS was interfaced with the IRGA via a stainless steel capillary inserted 0.5 m into the sample air outlet tube of the IRGA (forming an open split), a gas-tight pump, and a sample loop attached to the eight-port Valco valve of the continuous-flow interface. Air was pumped through the 0.25-mL sample loop at 10 mL s(-1) (a flushing frequency of 40 Hz). Air samples were analysed at intervals of approx. 2.8 min. Whole system precision was tested in the field using air mixed from pure CO2 and CO2-free air by means of mass flow controllers. The standard deviation of repeated single measurements was 0.21-0.07 per thousand for delta13C and 0.34-0.14 per thousand for delta18O of CO2 in air with mixing ratios ranging between 200-800 micromol mol(-1). The CO2 peak area measured by the IRMS was proportional to the CO2 mixing ratio (r2 = 1.00), allowing estimation of sample air CO2 mixing ratio from IRMS data. A 1-day long measurement cycle of CO2, delta13C and delta18O of air sampled above the grassland canopy was used to test the system for Keeling plot applications. Delta18O exhibited a clear diurnal cycle (4 per thousand range), but short-term (1-h interval) variability was small (average SD 0.38 per thousand). Yet, the correlation between delta18O and CO2 mixing ratio was relatively weak, and this was true for both the whole data set and 1-h subsets. Conversely, the delta13C of all 541 samples measured during the 25.2-h interval fitted well the Keeling regression (r2 = 0.99), yielding an intercept of -27.40 per thousand (+/-0.07 per thousand SE). Useful Keeling regressions (r2 > 0.9, average r2 = 0.96) also resulted from data collected over 1-h intervals of the 12-h long twilight and dark period. These indicated that 13C content of ecosystem respiration was approx. constant near -27.6 per thousand. The precision of the present system is similar to that of current techniques used in ecosystem studies which employ flask sampling and a laboratory-based CF-IRMS. Sampling (and measurement) frequency is greatly increased relative to systems based on flask sampling, and sampling time (0.025 s per sample) is decreased. These features increase the probability for sampling the entire CO2 range which occurs in a given time window. The system obviates sample storage problems, greatly minimises handling needs, and allows extended campaigns of high frequency sampling and analysis with minimal attendance.

Atmosphere↗

PubMed2005

Ty1-copia retrotransposon-based SSAP marker development in cashew (Anacardium occidentale L.).

The most popular retrotransposon-based molecular marker system in use at the present time is the sequence-specific amplification polymorphism (SSAP) system . This system exploits the insertional polymorphism of long terminal repeat (LTR) retrotransposons around the genome. Because the LTR sequence is used to design primers for this method, its successful application requires sequence information from the terminal region of the mobile elements . In this study, two LTR sequences were isolated from the cashew genome and used successfully to develop SSAP marker systems. These were shown to have higher levels of polymorphism than amplified fragment length polymorphic markers for this species.

Amino Acid Sequence↗

PubMed2003

"In vivo" monitoring of neuronal network activity in zebrafish by two-photon Ca(2+) imaging.

The zebrafish larva is a powerful model for the analysis of behaviour and the underlying neuronal network activity during early stages of development. Here we employ a new approach of "in vivo" Ca(2+) imaging in this preparation. We demonstrate that bolus injection of membrane-permeable Ca(2+) indicator dyes into the spinal cord of zebrafish larvae results in rapid staining of essentially the entire spinal cord. Using two-photon imaging, we could monitor Ca(2+) signals simultaneously from a large population of spinal neurons with single-cell resolution. To test the method, Ca(2+) transients were produced by iontophoretic application of glutamate and, as observed for the first time in a living preparation, of GABA or glycine. Glycine-evoked Ca(2+) transients were blocked by the application of strychnine. Sensory stimuli that trigger escape reflexes in mobile zebrafish evoked Ca(2+) transients in distinct neurons of the spinal network. Moreover, long-term recordings revealed spontaneous Ca(2+) transients in individual spinal neurons. Frequently, this activity occurred synchronously among many neurons in the network. In conclusion, the new approach permits a reliable analysis with single-cell resolution of the functional organisation of developing neuronal networks.

Animals↗

PubMed1986

Uptake of endogenous cholesterol by a synthetic lipoprotein.

The addition of cholesterol-poor phospholipid liposomes to canine plasma in vivo and in vitro substantially alters the distribution of phospholipids, apoproteins, and, especially, cholesterol. In vivo, intravenously injected phospholipid liposomes remain discrete particles, which are readily distinguished from the normally occurring lipoproteins by their buoyant density and electrophoretic mobility. They acquire unesterified cholesterol from endogenous sources, thereby producing an acute rise in the concentration of this sterol in plasma. The liposomes also accumulate endogenous proteins, one of which is identified as apolipoprotein A-I. In vitro, phospholipid liposomes incubated with plasma acquire unesterified cholesterol and apolipoprotein A-I at the expense of high-density lipoproteins (HDL), the major carrier of cholesterol in normal canine plasma. In exchange, the HDL particles are enriched in phospholipids and become larger. At sufficiently high concentrations, the liposomes nearly completely deplete HDL of its unesterified cholesterol. Thus, there are generated two types of particles, both rich in apolipoprotein A-I and phospholipid, but one (modified HDL) containing mainly esterified cholesterol in its core and the other (modified liposomes) containing mainly unesterified cholesterol at its surface. It is concluded that phospholipid liposomes produce important changes in the distribution of lipids and protein in canine plasma, particularly at the expense of HDL. These changes appear to favor the mobilization of tissue cholesterol into the plasma, and may have application to atherosclerosis.

Animals↗

PubMed1994

Facilitation of health care delivery through enhanced communications.

To realize the advantages of advanced computing technology in medicine we will have to blend computing and communications facilities into a seamless entity that can support ubiquitous computing for medical use. Work-group computing applications, high speed networks linking a multiplicity of servers, and mobile computing platforms can provide the next generation of devices and services for the physician. Ultimately, the biggest challenge for communications and computing in medicine will be found in the requirement for standards in semantics and syntax in the highest levels of the OSI model. We present here our view of the functional requirements for physician communications and computing to meet standard medical practice in Western societies.

Communication↗

PubMed2004

Score comparability of short forms and computerized adaptive testing: Simulation study with the activity measure for post-acute care.

OBJECTIVE: To compare simulated short-form and computerized adaptive testing (CAT) scores to scores obtained from complete item sets for each of the 3 domains of the Activity Measure for Post-Acute Care (AM-PAC). DESIGN: Prospective study. SETTING: Six postacute health care networks in the greater Boston metropolitan area, including inpatient acute rehabilitation, transitional care units, home care, and outpatient services. PARTICIPANTS: A convenience sample of 485 adult volunteers who were receiving skilled rehabilitation services. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Inpatient and community-based short forms and CAT applications were developed for each of 3 activity domains (physical & mobility, personal care & instrumental, applied cognition) using item pools constructed from new items and items from existing postacute care instruments. RESULTS: Simulated CAT scores correlated highly with score estimates from the total item pool in each domain (4- and 6-item CAT r range,.90-.95; 10-item CAT r range,.96-.98). Scores on the 10-item short forms constructed for inpatient and community settings also provided good estimates of the AM-PAC item pool scores for the physical & movement and personal care & instrumental domains, but were less consistent in the applied cognition domain. Confidence intervals around individual scores were greater in the short forms than for the CATs. CONCLUSIONS: Accurate scoring estimates for AM-PAC domains can be obtained with either the setting-specific short forms or the CATs. The strong relationship between CAT and item pool scores can be attributed to the CAT's ability to select specific items to match individual responses. The CAT may have additional advantages over short forms in practicality, efficiency, and the potential for providing more precise scoring estimates for individuals.

Boston↗

PubMed2005

Reduced ambulatory activity after stroke: the role of balance, gait, and cardiovascular fitness.

OBJECTIVES: To determine ambulatory activity in a sample of community-dwelling people with chronic hemiparetic stroke and to examine whether deficits in balance and gait and cardiovascular and metabolic fitness are key determinants of ambulatory activity levels. DESIGN: Descriptive correlational. SETTING: Home and community. PARTICIPANTS: Twenty-eight men and 22 women (N=50) over the age 45 years with more than 6 months of hemiparetic gait after ischemic stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Ambulatory activity (total daily step activity), mobility deficit severity (Berg Balance Scale [BBS] scores, timed 10-m walks), and cardiovascular fitness (energy costs of hemiparetic gait, peak exercise capacity [VO2peak]). RESULTS: Mean ambulatory activity profiles were extremely low (2837 steps/d vs reported 5000-6000 steps/d in sedentary older adults). Ambulatory activity levels were strongly associated with BBS scores (r=.581, P<.001) and self-selected floor walking velocity (r=.554, P<.001). Participants also had profound cardiovascular deconditioning (mean VO2peak, 11.7+/-2.8 mL.kg(-1).min(-1)). The energy costs of hemiparetic gait were high (8.7+/-1.7 mL.kg(-1).min(-1)), representing 76% of physiologic fitness reserve. Although the relationships of economy of gait and VO2peak to ambulatory activity was not statistically significant, both the VO2peak and the physiologic fitness reserve, as expressed by fractional utilization, were strongly related to balance (r=.374, P=.02; r=-.430, P< .01, respectively.) The BBS predicted 30% of the variance in ambulatory activity. CONCLUSIONS: Ambulatory activity levels and cardiovascular fitness in patients with chronic stroke are extremely low. Mobility deficits, particularly in balance, are associated with low ambulatory activity. Balance-related inactivity may be an important factor in deconditioning. Further studies are needed to better understand whether task-oriented exercise enhances balance and whether increases in daily ambulatory activity yield improved cardiovascular fitness in chronic stroke survivors.

Aged↗