Showing papers by "Clarkson University published in 2011"

Paper Bioassay Based on Ceria Nanoparticles as Colorimetric Probes

Abstract: We report the first use of redox nanoparticles of cerium oxide as colorimetric probes in bioanalysis. The method is based on changes in the physicochemical properties of ceria nanoparticles, used here as chromogenic indicators, in response to the analyte. We show that these particles can be fully integrated in a paper-based bioassay. To construct the sensor, ceria nanoparticles and glucose oxidase were coimmobilized onto filter paper using a silanization procedure. In the presence of glucose, the enzymatically generated hydrogen peroxide induces a visual color change of the ceria nanoparticles immobilized onto the bioactive sensing paper, from white-yellowish to dark orange, in a concentration-dependent manner. A detection limit of 0.5 mM glucose with a linear range up to 100 mM and a reproducibility of 4.3% for n = 11 ceria paper strips were obtained. The assay is fully reversible and can be reused for at least 10 consecutive measurement cycles, without significant loss of activity. Another unique featur...

Monitoring of Posture Allocations and Activities by a Shoe-Based Wearable Sensor

Abstract: Monitoring of posture allocations and activities enables accurate estimation of energy expenditure and may aid in obesity prevention and treatment. At present, accurate devices rely on multiple sensors distributed on the body and thus may be too obtrusive for everyday use. This paper presents a novel wearable sensor, which is capable of very accurate recognition of common postures and activities. The patterns of heel acceleration and plantar pressure uniquely characterize postures and typical activities while requiring minimal preprocessing and no feature extraction. The shoe sensor was tested in nine adults performing sitting and standing postures and while walking, running, stair ascent/descent and cycling. Support vector machines (SVMs) were used for classification. A fourfold validation of a six-class subject-independent group model showed 95.2% average accuracy of posture/activity classification on full sensor set and over 98% on optimized sensor set. Using a combination of acceleration/pressure also enabled a pronounced reduction of the sampling frequency (25 to 1 Hz) with out significant loss of accuracy (98% versus 93%). Subjects had shoe sizes (US) M9.5-11 and W7-9 and body mass index from 18.1 to 39.4 kg/m2 and thus suggesting that the device can be used by individuals with varying anthropometric characteristics.

Comprehensive Bench- and Pilot-Scale Investigation of Trace Organic Compounds Rejection by Forward Osmosis

Abstract: Forward osmosis (FO) is a membrane separation technology that has been studied in recent years for application in water treatment and desalination. It can best be utilized as an advanced pretreatment for desalination processes such as reverse osmosis (RO) and nanofiltration (NF) to protect the membranes from scaling and fouling. In the current study the rejection of trace organic compounds (TOrCs) such as pharmaceuticals, personal care products, plasticizers, and flame-retardants by FO and a hybrid FO-RO system was investigated at both the bench- and pilot-scales. More than 30 compounds were analyzed, of which 23 nonionic and ionic TOrCs were identified and quantified in the studied wastewater effluent. Results revealed that almost all TOrCs were highly rejected by the FO membrane at the pilot scale while rejection at the bench scale was generally lower. Membrane fouling, especially under field conditions when wastewater effluent is the FO feed solution, plays a substantial role in increasing the rejectio...

Pore structure features of pervious concretes proportioned for desired porosities and their performance prediction

Abstract: The pore structure features such as the pore volume fractions, pore sizes, specific surface areas, and connectivity dictate the properties of any porous material. In this paper, an analysis of the pore structure features of pervious concretes designed for similar porosities using two different proportioning methods – one with higher paste contents and lower compactive efforts and another with lower paste contents and higher compactive efforts – is carried out. The porosities (both from volumetric and image analysis based methods) and characteristic pore sizes obtained from morphological functions are found to be statistically similar for the high-paste and low-paste content mixtures, while the low-paste content mixtures show a higher specific surface area of pores. The extracted pore structure features, when used in the Katz–Thompson equation for permeability prediction, result in over-estimation of permeability for specimens with larger pore sizes. A correction factor for the Katz–Thompson constant is found to be linearly related to the granulometry-based pore sizes.

Microemulsions as topical drug delivery vehicles: in-vitro transdermal studies of a model hydrophilic drug.

Abstract: Microemulsions with a 58:42 weight ratio of dioctyl sodium sulphosuccinate: octanol and containing 15, 35, and 68% water have been tested for their ability to transport glucose across human cadaver skin. A flow-through multisample skin diffusion cell showed that both the 35 and 68% water microemulsions caused enhanced (approximately 30-fold) transport of glucose. No transport was discernible for the 15% water microemulsion. Differences in percutaneous glucose transport were shown to parallel differences in the diffusion of water within the microemulsion vehicles before application to the skin.

Automatic Detection of Temporal Gait Parameters in Poststroke Individuals

Abstract: Approximately one-third of people who recover from a stroke require some form of assistance to walk. Repetitive task-oriented rehabilitation interventions have been shown to improve motor control and function in people with stroke. Our long-term goal is to design and test an intensive task-oriented intervention that will utilize the two primary components of constrained-induced movement therapy: massed, task-oriented training and behavioral methods to increase use of the affected limb in the real world. The technological component of the intervention is based on a wearable footwear-based sensor system that monitors relative activity levels, functional utilization, and gait parameters of affected and unaffected lower extremities. The purpose of this study is to describe a methodology to automatically identify temporal gait parameters of poststroke individuals to be used in assessment of functional utilization of the affected lower extremity as a part of behavior enhancing feedback. An algorithm accounting for intersubject variability is capable of achieving estimation error in the range of 2.6-18.6% producing comparable results for healthy and poststroke subjects. The proposed methodology is based on inexpensive and user-friendly technology that will enable research and clinical applications for rehabilitation of people who have experienced a stroke.

New Product Exploration Under Environmental Turbulence

Abstract: This study identifies two organizational factors that foster explorative products, willingness to cannibalize and future-oriented market scanning, and examines whether the relationships of these factors with exploration are contingent on environmental turbulence in customer, competitor, and technological sectors. The study analyzes data from 145 U.S. public manufacturing firms to examine the relationship between the two organizational factors and the degree to which the firms pursue explorative new products---new products that are meaningfully distinct from competing alternatives. Results suggest that both willingness to cannibalize and future-oriented market scanning promote explorative new products. The relationship of willingness to cannibalize with explorative products is stronger under customer turbulence. In contrast, the relationship of future-oriented market scanning with explorative products is weaker under customer and competitive turbulence and stronger under technological turbulence. The study concludes that the two organizational factors promote explorative new products, but their effectiveness is contingent on turbulence in different sectors of the firm's environment.

Taking the reins: the effects of new leader status and leadership style on team performance.

Abstract: New leaders face a challenging task when they take charge of their teams. They have to determine how best to guide the work process, and they must understand how their behaviors will affect the members of their team. This research examines how a newly assigned team leader's status moderates subordinates' reactions to different leadership styles to affect assessments of the leader's self-confidence and effectiveness, and how this impacts team performance. Across 2 experimental studies, results demonstrate that low-status leaders are rated as more effective when they use a directive style, whereas high-status leaders are viewed as more effective when they use a participative style, and this relationship is mediated by perceptions of self-confidence. In addition, teams whose leaders are viewed more favorably perform better on a complex group task. These findings imply that low-status individuals are able to enhance their level of personal power by drawing on whatever positional power they hold, whereas high-status individuals are better off relying solely on their personal power to influence others. This research also provides a clear demonstration that assessments of new leaders' behaviors are subject to an appraisal that is clouded by observers' status perceptions and attributions.

Characterization of residential wood combustion particles using the two-wavelength aethalometer.

Abstract: In the United States, residential wood combustion (RWC) is responsible for 7.0% of the national primary PM2.5 emissions. Exposure to RWC smoke represents a potential human health hazard. Organic components of wood smoke particles absorb light at 370 nm more effectively than 880 nm in two- wavelength aethalometer measurements. This enhanced absorption (Delta-C = BC370 nmBC880 nm) can serve as an indicator of RWC particles. In this study, aethalometer Delta-C data along with measurements of molecular markers and potassium in PM2.5 were used to identify the presence of airborne RWC particles in Rochester, NY. The aethalometer data were corrected for the loading effect. Delta-C was found to strongly correlate with wood smoke markers (levoglucosan and potassium) during the heating season. No statistically significant correlation wasfoundbetweenDelta-Candvehicleexhaustmarkers.TheDelta-Cvalueswere substantially higher during winter compared to summer. The winter diurnal pattern showed an evening peak around 21:00 that was particularly enhanced on weekends. A relationship between Delta-C and PM2.5 was found that permits the estimation of the contribution of RWC particles to the PM mass. RWC contributed 17.3% to the PM2.5 concentration during the winter. Exponential decay was a good estimator for predicting Delta-C concentrations at different winter precipitation rates and different wind speeds. Delta-C was also sensitive to remote forest fire smoke.

A Tighter Piecewise Linear Approximation of Quadratic Cost Curves for Unit Commitment Problems

Abstract: This letter provides a tighter piecewise linear approximation of generating units' quadratic cost curves (QCCs) for unit commitment (UC) problems. In order to facilitate the UC optimization process with efficient mixed-integer linear programing (MILP) solvers, QCCs are piecewise linearized for converting the original mixed-integer quadratic programming (MIQP) problem into an MILP problem. Traditionally, QCCs are piecewise linearized by evenly dividing the entire real power region into segments. This letter discusses a rigorous segment partition method for obtaining a set of optimal segment points by minimizing the difference between chord and arc lengths, in order to derive a tighter piecewise linear approximation of QCCs and, in turn, a better UC solution as compared to the equipartition method. Numerical test results show the effectiveness of the proposed method on a tighter piecewise linear approximation for better UC solutions.

Decay of bacterial pathogens, fecal indicators, and real-time quantitative PCR genetic markers in manure-amended soils.

Abstract: This study examined persistence and decay of bacterial pathogens, fecal indicator bacteria (FIB), and emerging real-time quantitative PCR (qPCR) genetic markers for rapid detection of fecal pollution in manure-amended agricultural soils. Known concentrations of transformed green fluorescent protein-expressing Escherichia coli O157:H7/pZs and red fluorescent protein-expressing Salmonella enterica serovar Typhimurium/pDs were added to laboratory-scale manure-amended soil microcosms with moisture contents of 60% or 80% field capacity and incubated at temperatures of -20°C, 10°C, or 25°C for 120 days. A two-stage first-order decay model was used to determine stage 1 and stage 2 first-order decay rate coefficients and transition times for each organism and qPCR genetic marker in each treatment. Genetic markers for FIB (Enterococcus spp., E. coli, and Bacteroidales) exhibited decay rate coefficients similar to that of E. coli O157:H7/pZs but not of S. enterica serovar Typhimurium/pDs and persisted at detectable levels longer than both pathogens. Concentrations of these two bacterial pathogens, their counterpart qPCR genetic markers (stx1 and ttrRSBCA, respectively), and FIB genetic markers were also correlated (r = 0.528 to 0.745). This suggests that these qPCR genetic markers may be reliable conservative surrogates for monitoring fecal pollution from manure-amended land. Host-associated qPCR genetic markers for microbial source tracking decayed rapidly to nondetectable concentrations, long before FIB, Salmonella enterica serovar Typhimurium/pDs, and E. coli O157:H7/pZs. Although good indicators of point source or recent nonpoint source fecal contamination events, these host-associated qPCR genetic markers may not be reliable indicators of nonpoint source fecal contamination events that occur weeks following manure application on land.

Estimating clinically important change in gait speed in people with stroke undergoing outpatient rehabilitation.

Abstract: Background and Purpose:Gait speed is commonly used to assess walking ability in people with stroke. It is not clear how much change in gait speed reflects an important change in walking ability. The purpose of this study was to estimate clinically important changes in gait speed by using 2 different

Bicomponent Microneedle Array Biosensor for Minimally-Invasive Glutamate Monitoring

Abstract: This article describes the design of a new and attractive minimally-invasive bicomponent microneedle sensing device for the electrochemical monitoring of the excitatory neurotransmitter glutamate and glucose. The new device architecture relies on the close integration of solid and hollow microneedles into a single biosensor array device containing multiple microcavities. Such microcavities facilitate the electropolymeric entrapment of the recognition enzyme within each microrecess. The resulting microneedle biosensor array can be employed as a minimally-invasive on-body transdermal patch, obviating the extraction/sampling of the biological fluid, thereby simplifying device requirements. The new concept is demonstrated for the electropolymeric entrapment of glutamate oxidase and glucose oxidase within a poly(o-phenylenediamine) (PPD) thin film. The PPD-based enzyme entrapment methodology enables the effective rejection of coexisting electroactive interferents without compromising the sensitivity or response time of the device. The resulting microneedle-based glutamate and glucose biosensors thus exhibit high selectivity, sensitivity, speed, and stability in both buffer and undiluted human serum. High-fidelity glutamate measurements down to the 10 µM level are obtained in serum. The attractive recess design also serves to protect the enzyme layer upon insertion into the skin. This simple, yet robust microneedle design is well-suited for diverse biosensing applications in which real-time metabolite monitoring is a core requirement.

Secondary organic aerosol from ozonolysis of biogenic volatile organic compounds: chamber studies of particle and reactive oxygen species formation.

Abstract: The formation of secondary organic aerosol (SOA) produced from α-pinene, linalool, and limonene by ozonolysis was examined using a dynamic chamber system that allowed the simulation of ventilated indoor environments. Experiments were conducted at typical room temperatures and air exchange rates. Limonene ozonolysis produced the highest SOA mass concentrations and linalool the lowest with α-pinene being intermediate. Simplified empirical modeling simulations were conducted to provide insights into reaction chemistry. Assessment of variability of particle-bound reactive oxygen species (ROS) may be important in the understanding of health effects associated with particulate matter. The ROS intensities defined as ROS/SOA mass were found to be moderately correlated with the SOA densities. Greater ROS intensities were observed for the cases where ozone was in excess. ROS intensities approached a relatively constant value in the region where ozone was in deficit. The estimated initial ROS half-life time was approximately 6.5 h at room temperature suggesting the time sensitivity of ROS measurements. The ROS formed from terpenoid ozonolysis could be separated into three categories: short-lived/high reactive/volatile, semivolatile/relatively stable and nonvolatile/low reactive species based on ROS measurements under various conditions. Such physical characterization of the ROS in terms of reactivity and volatility provides some insights into the nature of ROS.

Identifying transient protein-protein interactions in EphB2 signaling by blue native PAGE and mass spectrometry.

Abstract: Receptor tyrosine kinases (RTKs) are proteins that upon ligand stimulation undergo dimerization and autophosphorylation. Eph receptors (EphRs) are RTKs that are found in different cell types, from both tissues that are developing and from mature tissues, and play important roles in the development of the central nervous system and peripheral nervous system. EphRs also play roles in synapse formation, neural crest formation, angiogenesis and in remodeling the vascular system. Interaction of EphRs with their ephrin ligands lead to activation of signal transduction pathways and formation of many transient protein-protein interactions that ultimately leads to cytoskeletal remodeling. However, the sequence of events at the molecular level is not well understood. We used blue native PAGE and MS to analyze the transient protein-protein interactions that resulted from the stimulation of EphB2 receptors by their ephrinB1-Fc ligands. We analyzed the phosphotyrosine-containing protein complexes immunoprecipitated from the cell lysates of both unstimulated (-) and ephrinB1-Fc-stimulated (+) NG108 cells. Our experiments allowed us to identify many signaling proteins, either known to be part of EphB2 signaling or new for this pathway, which are involved in transient protein-protein interactions upon ephrinB1-Fc stimulation. These data led us to investigate the roles of proteins such as FAK, WAVEs and Nischarin in EphB2 signaling.

Outcome measures in neurological physical therapy practice: part I. Making sound decisions.

Abstract: Standardized outcome measures (OMs) are a vital part of evidence-based practice. Despite the recognition of the importance of OMs, recent evidence suggests that the use of OMs in clinical practice is limited. Selecting the most appropriate OM enhances clinical practice by (1) identifying and quantifying body function and structure limitations; (2) formulating the evaluation, diagnosis, and prognosis; (3) informing the plan of care; and (4) helping to evaluate the success of physical therapy interventions. This article (Part I) is the first of a 2-part series on the process of selecting OMs in neurological clinical practice. We introduce a decision-making framework to guide the selection of OMs and discuss 6 main factors-what to measure, the purpose of the measure, the type of measure, patient and clinic factors, psychometric factors, and feasibility-that should be considered when selecting OMs for clinical use. The framework will then be applied to a patient case in Part II of the series (see the article "Outcome Measures in Neurological Physical Therapy Practice: Part II. A Patient-Centered Process" in this issue).

Evolution of extreme body size disparity in monitor lizards (varanus)

Abstract: within clades. In this study, we examined size evolution in monitor lizards (Varanus), a clade that includes the largest extant lizard species, the Komodo dragon (V. komodoensis), as well as diminutive species that are nearly four orders of magnitude smaller in adult body mass. We demonstrate that the remarkable body size disparity of this clade is a consequence of different selective demands imposed by three major habitat use patterns—arboreality, terrestriality, and rock-dwelling. We reconstructed phylogenetic relationships and ancestral habitat use and applied model selection to determine that the best-fitting evolutionary models for species’ adult size are those that infer oppositely directed adaptive evolution associated with terrestriality and rockdwelling, with terrestrial lineages evolving extremely large size and rock-dwellers becoming very small. We also show that habitat use affects the evolution of several ecologically important morphological traits independently of body size divergence. These results suggest that habitat use exerts a strong, multidimensional influence on the evolution of morphological size and shape disparity in monitor lizards.

Obstacles in Using Frameworks and APIs: An Exploratory Study of Programmers' Newsgroup Discussions

Abstract: Large software frameworks and APIs can be hard to learn and use, impeding software productivity. But what are the specific challenges that programmers actually face when using frameworks and APIs in practice? What makes APIs hard to use, and what can be done to alleviate the problems associated with API usability and learnability? To explore these questions, we conducted an exploratory study in which we manually analyzed a set of newsgroup discussions about specific challenges that programmers had about a software framework. Based on this set of data, we identified several categories of obstacles in using APIs. We discussed what could be done to help overcome these obstacles.

Responsive interface switchable by logically processed physiological signals: toward "smart" actuators for signal amplification and drug delivery.

Abstract: Biomarkers characteristic of liver injury, alanine transaminase and lactate dehydrogenase, were processed by an enzyme-based system functioning as a logic AND gate. The NAD+ output signal produced by the system upon its activation in the presence of both biomarkers was then biocatalytically converted to a decrease in pH. The acidic pH value biocatalytically produced by the system as a response to the biomarkers triggered the restructuring of a polymer-modified electrode interface. This allowed a soluble redox species to approach the electrode surface, thus switching the electrochemical reaction ON. The redox transformations activated by the biochemical signals resulted in an amplification of signals. This system represents the first example of an integrated sensing-actuating chemical device with the implemented AND Boolean logic for processing natural biomarkers at their physiologically relevant concentrations.