Trace detection of specific viable bacteria using tetracysteine-tagged bacteriophages.

PubMed

Wu, Lina; Luan, Tian; Yang, Xiaoting; Wang, Shuo; Zheng, Yan; Huang, Tianxun; Zhu, Shaobin; Yan, Xiaomei

2014-01-07

Advanced methods are urgently needed to determine the identity and viability of trace amounts of pathogenic bacteria in a short time. Existing approaches either fall short in the accurate assessment of microbial viability or lack specificity in bacterial identification. Bacteriophages (or phages for short) are viruses that exclusively infect bacterial host cells with high specificity. As phages infect and replicate only in living bacterial hosts, here we exploit the strategy of using tetracysteine (TC)-tagged phage in combination with biarsenical dye to the discriminative detection of viable target bacteria from dead target cells and other viable but nontarget bacterial cells. Using recombinant M13KE-TC phage and Escherichia coli ER2738 as a model system, distinct differentiation between individual viable target cells from dead target cells was demonstrated by flow cytometry and fluorescence microscopy. As few as 1% viable E. coli ER2738 can be accurately quantified in a mix with dead E. coli ER2738 by flow cytometry. With fluorescence microscopic measurement, specific detection of as rare as 1 cfu/mL original viable target bacteria was achieved in the presence of a large excess of dead target cells and other viable but nontarget bacterial cells in 40 mL artificially contaminated drinking water sample in less than 3 h. This TC-phage-FlAsH approach is sensitive, specific, rapid, and simple, and thus shows great potential in water safety monitoring, health surveillance, and clinical diagnosis of which trace detection and identification of viable bacterial pathogens is highly demanded.

Models and Procedures for Evaluating Government Provided Leisure Services.

ERIC Educational Resources Information Center

McLean, Christine

1978-01-01

The government attempted to set up a viable management information and feedback system for evaluating accountability in services delivery. Conceptual models for agency goals and services delivery were designed and measures were developed in the provision of leisure and recreational services. Two citizen surveys are described. (Author/CTM)

Oral supplementation of Bifidobacterium longum strain BR-108 alters cecal microbiota by stimulating gut immune system in mice irrespectively of viability.

PubMed

Makioka, Yuko; Tsukahara, Takamitsu; Ijichi, Tetsuo; Inoue, Ryo

2018-03-20

Effect on cecal microbiota and gene expression of various cytokines in ileal Peyer's patches and cecal tissues were compared between viable and heat-killed Bifidobacterium longum strain BR-108 (BR-108) using a mouse model. Irrespectively of viability, oral supplementation of BR-108 altered the cecal microbiota and stimulated gene expression of cytokines such as IL-6 and IL-10 in ileal Peyer's patches and cecal tissue of mice. In addition, BR-108 supplementation significantly affected the relative abundance of bacterial genera and family, Oscillospira, Bacteroides and S24-7. The abundance of these bacterial genera and family strongly correlated with gene expression induced by BR-108. This study demonstrated that the effect of heat-killed BR-108 on the mouse cecal microbiota is similar to that of viable BR-108, most likely due to stimulation of the gut immune system by both heat-killed and viable BR-108 is also similar.

Development of a Two-Dimensional Model for Predicting Transdermal Permeation with the Follicular Pathway: Demonstration with a Caffeine Study.

PubMed

Kattou, Panayiotis; Lian, Guoping; Glavin, Stephen; Sorrell, Ian; Chen, Tao

2017-10-01

The development of a new two-dimensional (2D) model to predict follicular permeation, with integration into a recently reported multi-scale model of transdermal permeation is presented. The follicular pathway is modelled by diffusion in sebum. The mass transfer and partition properties of solutes in lipid, corneocytes, viable dermis, dermis and systemic circulation are calculated as reported previously [Pharm Res 33 (2016) 1602]. The mass transfer and partition properties in sebum are collected from existing literature. None of the model input parameters was fit to the clinical data with which the model prediction is compared. The integrated model has been applied to predict the published clinical data of transdermal permeation of caffeine. The relative importance of the follicular pathway is analysed. Good agreement of the model prediction with the clinical data has been obtained. The simulation confirms that for caffeine the follicular route is important; the maximum bioavailable concentration of caffeine in systemic circulation with open hair follicles is predicted to be 20% higher than that when hair follicles are blocked. The follicular pathway contributes to not only short time fast penetration, but also the overall systemic bioavailability. With such in silico model, useful information can be obtained for caffeine disposition and localised delivery in lipid, corneocytes, viable dermis, dermis and the hair follicle. Such detailed information is difficult to obtain experimentally.

Glass Effect in Inbreeding-Avoidance Systems: Minimum Viable Population for Outbreeders

NASA Astrophysics Data System (ADS)

Tainaka, Kei-ichi; Itoh, Yoshiaki

1996-10-01

Many animals, birds and plants have evolved mechanisms to avoid inbreeding between close relatives.Such mating systems may have developed several methods for restricting mate choice.If fragmentation of habitats becomes serious, these methods may lead to a lack of acceptable mates. We call this “glass effect”which is a generalization of the so-called Allee effect.We present two inbreeding-avoidance (outbreeding) models.Both models show that outbreeders have a high risk infragmented environments.We thus obtain the minimum viable population (MVP). It is found that the value of MVP amounts to the range from several hundred to several thousand individuals.While this value is much larger than thoseobtained by the previous demographic theories,it is consistent with recent empirical estimations.Moreover, we find that the glass effect is caused bydynamically induced clusters of relatives.This suggests that genetic variation will be decreased by the outbreeding in a highly fragmented environment.

Importance of DNA repair in tumor suppression

NASA Astrophysics Data System (ADS)

Brumer, Yisroel; Shakhnovich, Eugene I.

2004-12-01

The transition from a normal to cancerous cell requires a number of highly specific mutations that affect cell cycle regulation, apoptosis, differentiation, and many other cell functions. One hallmark of cancerous genomes is genomic instability, with mutation rates far greater than those of normal cells. In microsatellite instability (MIN tumors), these are often caused by damage to mismatch repair genes, allowing further mutation of the genome and tumor progression. These mutation rates may lie near the error catastrophe found in the quasispecies model of adaptive RNA genomes, suggesting that further increasing mutation rates will destroy cancerous genomes. However, recent results have demonstrated that DNA genomes exhibit an error threshold at mutation rates far lower than their conservative counterparts. Furthermore, while the maximum viable mutation rate in conservative systems increases indefinitely with increasing master sequence fitness, the semiconservative threshold plateaus at a relatively low value. This implies a paradox, wherein inaccessible mutation rates are found in viable tumor cells. In this paper, we address this paradox, demonstrating an isomorphism between the conservatively replicating (RNA) quasispecies model and the semiconservative (DNA) model with post-methylation DNA repair mechanisms impaired. Thus, as DNA repair becomes inactivated, the maximum viable mutation rate increases smoothly to that of a conservatively replicating system on a transformed landscape, with an upper bound that is dependent on replication rates. On a specific single fitness peak landscape, the repair-free semiconservative system is shown to mimic a conservative system exactly. We postulate that inactivation of post-methylation repair mechanisms is fundamental to the progression of a tumor cell and hence these mechanisms act as a method for the prevention and destruction of cancerous genomes.

Formulaic Language in Computer-Supported Communication: Theory Meets Reality.

ERIC Educational Resources Information Center

Wray, Alison

2002-01-01

Attempts to validate a psycholinguistic model of language processing. One experiment designed to provide insight into the model is TALK, is a system developed to promote conversational fluency in non-speaking individuals. TALK, designed primarily for people with cerebral palsy and motor neuron disease. Talk is demonstrated to be a viable tool for…

The Personal Learning Environment and the Human Condition: From Theory to Teaching Practice

ERIC Educational Resources Information Center

Johnson, Mark; Liber, Oleg

2008-01-01

We present the Personal Learning Environment (PLE) as a practical intervention concerning the organization of technology in education. We explain this by proposing a cybernetic model of the "Personal Learner" using Beer's Viable System Model (VSM). Using the VSM, we identify different regulatory mechanisms that maintain viability for learners, and…

Modeling the world in a spreadsheet: Environmental simulation on a microcomputer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cartwright, T.J.

1993-12-31

This article focuses on the following: Modeling Natural Systems Blowing Smoke; Atmospheric Dispersion of Air Pollution Running Water; The Underground Transport of Pollutants Preserving the Species; Determining Minimum Viable Population Sustainable Yield; Managing the Forest for the Trees Here Comes the Sun; Solar Energy from a Flat-Plate Collector Modeling Social Systems Macroeconomic Policy; Econometrics and the Klein Model Urban Form; The Lowry Model of Population Distribution Affordable Housing; The Bertaud/World Bank Model Traffic on the Roads; Modeling Trip Generation and Trip Distribution Throwing Things Away; A Model for Waste Management Apples and Oranges; and An Environmental Impact Assessment Model Modelingmore » Artificial Systems Life in a Spreadsheet.« less

Overcoming Barriers To IVHS -- Lessons From Other Technologies, Final Task F Report, Model Advanced Traffic Management System Franchise Agreement

DOT National Transportation Integrated Search

1995-08-25

VIABLE ADVANCED TRAFFIC MANAGEMENT SYSTEMS WILL BE CENTRAL TO THE : DEVELOPMENT OF ITS TECHNOLOGIES, AND CRITICAL TO THE DELIVERY OF MANY PRIVATE SECTOR ITS SERVICES TO THE PUBLIC. BY ITS VERY NATURE, HOWEVER, ATMS RELIES HEAVILY ON ACCESS TO THE PUB...

Swarming Unmanned Aircraft Systems

DTIC Science & Technology

2008-09-01

systems may become a viable part of strategy and tactics in the future. Specific to Unmanned Aircraft Sys- tems ( UAS ). they see a strong and central...system itself. They do not want to limit direct access to only Military Occupational Specialty (MOS) trained UAS operators. Rather, they feel that...Collaborating (SASC) characteristics within swarms of UAS that support operations. Technical Approach The approach taken to model this system begins with an

A Reliable Methodology for Determining Seed Viability by Using Hyperspectral Data from Two Sides of Wheat Seeds.

PubMed

Zhang, Tingting; Wei, Wensong; Zhao, Bin; Wang, Ranran; Li, Mingliu; Yang, Liming; Wang, Jianhua; Sun, Qun

2018-03-08

This study investigated the possibility of using visible and near-infrared (VIS/NIR) hyperspectral imaging techniques to discriminate viable and non-viable wheat seeds. Both sides of individual seeds were subjected to hyperspectral imaging (400-1000 nm) to acquire reflectance spectral data. Four spectral datasets, including the ventral groove side, reverse side, mean (the mean of two sides' spectra of every seed), and mixture datasets (two sides' spectra of every seed), were used to construct the models. Classification models, partial least squares discriminant analysis (PLS-DA), and support vector machines (SVM), coupled with some pre-processing methods and successive projections algorithm (SPA), were built for the identification of viable and non-viable seeds. Our results showed that the standard normal variate (SNV)-SPA-PLS-DA model had high classification accuracy for whole seeds (>85.2%) and for viable seeds (>89.5%), and that the prediction set was based on a mixed spectral dataset by only using 16 wavebands. After screening with this model, the final germination of the seed lot could be higher than 89.5%. Here, we develop a reliable methodology for predicting the viability of wheat seeds, showing that the VIS/NIR hyperspectral imaging is an accurate technique for the classification of viable and non-viable wheat seeds in a non-destructive manner.

A Reliable Methodology for Determining Seed Viability by Using Hyperspectral Data from Two Sides of Wheat Seeds

PubMed Central

Zhang, Tingting; Wei, Wensong; Zhao, Bin; Wang, Ranran; Li, Mingliu; Yang, Liming; Wang, Jianhua; Sun, Qun

2018-01-01

This study investigated the possibility of using visible and near-infrared (VIS/NIR) hyperspectral imaging techniques to discriminate viable and non-viable wheat seeds. Both sides of individual seeds were subjected to hyperspectral imaging (400–1000 nm) to acquire reflectance spectral data. Four spectral datasets, including the ventral groove side, reverse side, mean (the mean of two sides’ spectra of every seed), and mixture datasets (two sides’ spectra of every seed), were used to construct the models. Classification models, partial least squares discriminant analysis (PLS-DA), and support vector machines (SVM), coupled with some pre-processing methods and successive projections algorithm (SPA), were built for the identification of viable and non-viable seeds. Our results showed that the standard normal variate (SNV)-SPA-PLS-DA model had high classification accuracy for whole seeds (>85.2%) and for viable seeds (>89.5%), and that the prediction set was based on a mixed spectral dataset by only using 16 wavebands. After screening with this model, the final germination of the seed lot could be higher than 89.5%. Here, we develop a reliable methodology for predicting the viability of wheat seeds, showing that the VIS/NIR hyperspectral imaging is an accurate technique for the classification of viable and non-viable wheat seeds in a non-destructive manner. PMID:29517991

Template Directed Replication Supports the Maintenance of the Metabolically Coupled Replicator System

NASA Astrophysics Data System (ADS)

Könnyű, Balázs; Czárán, Tamás

2015-06-01

The RNA World scenario of prebiotic chemical evolution is among the most plausible conceptual framework available today for modelling the origin of life. RNA offers genetic and catalytic (metabolic) functionality embodied in a single chemical entity, and a metabolically cooperating community of RNA molecules would constitute a viable infrabiological subsystem with a potential to evolve into proto-cellular life. Our Metabolically Coupled Replicator System (MCRS) model is a spatially explicit computer simulation implementation of the RNA-World scenario, in which replicable ribozymes cooperate in supplying each other with monomers for their own replication. MCRS has been repeatedly demonstrated to be viable and evolvable, with different versions of the model improved in depth (chemical detail of metabolism) or in extension (additional functions of RNA molecules). One of the dynamically relevant extensions of the MCRS approach to prebiotic RNA evolution is the explicit inclusion of template replication into its assumptions, which we have studied in the present version. We found that this modification has not changed the behaviour of the system in the qualitative sense, just the range of the parameter space which is optimal for the coexistence of metabolically cooperating replicators has shifted in terms of metabolite mobility. The system also remains resistant and tolerant to parasitic replicators.

Validation, Optimization and Simulation of a Solar Thermoelectric Generator Model

NASA Astrophysics Data System (ADS)

Madkhali, Hadi Ali; Hamil, Ali; Lee, HoSung

2017-12-01

This study explores thermoelectrics as a viable option for small-scale solar thermal applications. Thermoelectric technology is based on the Seebeck effect, which states that a voltage is induced when a temperature gradient is applied to the junctions of two differing materials. This research proposes to analyze, validate, simulate, and optimize a prototype solar thermoelectric generator (STEG) model in order to increase efficiency. The intent is to further develop STEGs as a viable and productive energy source that limits pollution and reduces the cost of energy production. An empirical study (Kraemer et al. in Nat Mater 10:532, 2011) on the solar thermoelectric generator reported a high efficiency performance of 4.6%. The system had a vacuum glass enclosure, a flat panel (absorber), thermoelectric generator and water circulation for the cold side. The theoretical and numerical approach of this current study validated the experimental results from Kraemer's study to a high degree. The numerical simulation process utilizes a two-stage approach in ANSYS software for Fluent and Thermal-Electric Systems. The solar load model technique uses solar radiation under AM 1.5G conditions in Fluent. This analytical model applies Dr. Ho Sung Lee's theory of optimal design to improve the performance of the STEG system by using dimensionless parameters. Applying this theory, using two cover glasses and radiation shields, the STEG model can achieve a highest efficiency of 7%.

Tumor characterization in small animals using magnetic resonance-guided dynamic contrast enhanced diffuse optical tomography

NASA Astrophysics Data System (ADS)

Lin, Yuting; Thayer, Dave; Nalcioglu, Orhan; Gulsen, Gultekin

2011-10-01

We present a magnetic resonance (MR)-guided near-infrared dynamic contrast enhanced diffuse optical tomography (DCE-DOT) system for characterization of tumors using an optical contrast agent (ICG) and a MR contrast agent [Gd-diethylenetriaminepentaacetic acid (DTPA)] in a rat model. Both ICG and Gd-DTPA are injected and monitored simultaneously using a combined MRI-DOT system, resulting in accurate co-registration between two imaging modalities. Fisher rats bearing R3230 breast tumor are imaged using this hybrid system. For the first time, enhancement kinetics of the exogenous contrast ICG is recovered from the DCE-DOT data using MR anatomical a priori information. As tumors grow, they undergo necrosis and the tissue transforms from viable to necrotic. The results show that the physiological changes between viable and necrotic tissue can be differentiated more accurately based on the ICG enhancement kinetics when MR anatomical information is utilized.

Experimental validation of a sub-surface model of solar power for distributed marine sensor systems

NASA Astrophysics Data System (ADS)

Hahn, Gregory G.; Cantin, Heather P.; Shafer, Michael W.

2016-04-01

The capabilities of distributed sensor systems such as marine wildlife telemetry tags could be significantly enhanced through the integration of photovoltaic modules. Photovoltaic cells could be used to supplement the primary batteries for wildlife telemetry tags to allow for extended tag deployments, wherein larger amounts of data could be collected and transmitted in near real time. In this article, we present experimental results used to validate and improve key aspects of our original model for sub-surface solar power. We discuss the test methods and results, comparing analytic predictions to experimental results. In a previous work, we introduced a model for sub-surface solar power that used analytic models and empirical data to predict the solar irradiance available for harvest at any depth under the ocean's surface over the course of a year. This model presented underwater photovoltaic transduction as a viable means of supplementing energy for marine wildlife telemetry tags. The additional data provided by improvements in daily energy budgets would enhance the temporal and spatial comprehension of the host's activities and/or environments. Photovoltaic transduction is one method that has not been widely deployed in the sub-surface marine environments despite widespread use on terrestrial and avian species wildlife tag systems. Until now, the use of photovoltaic cells for underwater energy harvesting has generally been disregarded as a viable energy source in this arena. In addition to marine telemetry systems, photovoltaic energy harvesting systems could also serve as a means of energy supply for autonomous underwater vehicles (AUVs), as well as submersible buoys for oceanographic data collection.

Multispectral system analysis through modeling and simulation

NASA Technical Reports Server (NTRS)

Malila, W. A.; Gleason, J. M.; Cicone, R. C.

1977-01-01

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in Landsat data, examining system design and operational configuration, and development of information extraction techniques.

Multispectral system analysis through modeling and simulation

NASA Technical Reports Server (NTRS)

Malila, W. A.; Gleason, J. M.; Cicone, R. C.

1977-01-01

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in LANDSAT data, examining system design and operational configuration, and development of information extraction techniques.

Direct atomic force microscopy observation of DNA tile crystal growth at the single-molecule level.

PubMed

Evans, Constantine G; Hariadi, Rizal F; Winfree, Erik

2012-06-27

While the theoretical implications of models of DNA tile self-assembly have been extensively researched and such models have been used to design DNA tile systems for use in experiments, there has been little research testing the fundamental assumptions of those models. In this paper, we use direct observation of individual tile attachments and detachments of two DNA tile systems on a mica surface imaged with an atomic force microscope (AFM) to compile statistics of tile attachments and detachments. We show that these statistics fit the widely used kinetic Tile Assembly Model and demonstrate AFM movies as a viable technique for directly investigating DNA tile systems during growth rather than after assembly.

Space station onboard propulsion system: Technology study

NASA Technical Reports Server (NTRS)

Mcallister, J. G.; Rudland, R. S.; Redd, L. R.; Beekman, D. H.; Cuffin, S. M.; Beer, C. M.; Mccarthy, K. K.

1987-01-01

The objective was to prepare for the design of the space station propulsion system. Propulsion system concepts were defined and schematics were developed for the most viable concepts. A dual model bipropellant system was found to deliver the largest amount of payload. However, when resupply is considered, an electrolysis system with 10 percent accumulators requires less resupply propellant, though it is penalized by the amount of time required to fill the accumulators and the power requirements for the electrolyzer. A computer simulation was prepared, which was originally intended to simulate the water electrolysis propulsion system but which was expanded to model other types of systems such as cold gas, monopropellant and bipropellant storable systems.

Development of Parametric Mass and Volume Models for an Aerospace SOFC/Gas Turbine Hybrid System

NASA Technical Reports Server (NTRS)

Tornabene, Robert; Wang, Xiao-yen; Steffen, Christopher J., Jr.; Freeh, Joshua E.

2005-01-01

In aerospace power systems, mass and volume are key considerations to produce a viable design. The utilization of fuel cells is being studied for a commercial aircraft electrical power unit. Based on preliminary analyses, a SOFC/gas turbine system may be a potential solution. This paper describes the parametric mass and volume models that are used to assess an aerospace hybrid system design. The design tool utilizes input from the thermodynamic system model and produces component sizing, performance, and mass estimates. The software is designed such that the thermodynamic model is linked to the mass and volume model to provide immediate feedback during the design process. It allows for automating an optimization process that accounts for mass and volume in its figure of merit. Each component in the system is modeled with a combination of theoretical and empirical approaches. A description of the assumptions and design analyses is presented.

Pilot of a Learning Management System to Enhance Counselors' Relational Qualities through Mindfulness-Based Practices

ERIC Educational Resources Information Center

Ballinger, Julie Ann

2013-01-01

Mindfulness-based practices are associated with increased attentional qualities, improved self-focus styles, enhanced empathic understanding, and strengthened self-compassion, making these practices a viable addition to counselor training programs. However, current mindfulness training models are primarily designed for relief of psychological…

Introducing Systems Approaches

NASA Astrophysics Data System (ADS)

Reynolds, Martin; Holwell, Sue

Systems Approaches to Managing Change brings together five systems approaches to managing complex issues, each having a proven track record of over 25 years. The five approaches are: System Dynamics (SD) developed originally in the late 1950s by Jay Forrester Viable Systems Model (VSM) developed originally in the late 1960s by Stafford Beer Strategic Options Development and Analysis (SODA: with cognitive mapping) developed originally in the 1970s by Colin Eden Soft Systems Methodology (SSM) developed originally in the 1970s by Peter Checkland Critical Systems Heuristics (CSH) developed originally in the late 1970s by Werner Ulrich

Effects of cell condition, pH, and temperature on lead, zinc, and copper sorption to Acidithiobacillus caldus strain BC13

DOE Office of Scientific and Technical Information (OSTI.GOV)

John E. Aston; William A. Apel; Brady D. Lee

2010-12-01

This study describes the effects of cell condition, pH, and temperature on lead, zinc, and copper sorption to Acidithiobacillus caldus strain BC13 with a Langmuir model. Copper exhibited the highest loading capacity, 4.76 ± 0.28 mmol g-1, to viable cells at pH 5.5. The highest kL (binding-site affinity) observed was 61.2 ± 3.0 L mmol-1 to dehydrated cells at pH 4.0. The pHs that maximized loading capacities and binding-site affinities were generally between 4.0 and 5.5, where the sum of free-proton and complexed-metal concentrations was near a minimum. Of additional importance, lead, zinc, and copper sorbed to viable cells atmore » pH values as low as 1.5. Previous studies with other acidithiobacilli did not measure viable-cell sorption below pH 4.0. In separate experiments, desorption studies showed that far less copper was recovered from viable cells than any other metal or cell condition, suggesting that uptake may play an important role in copper sorption by At. caldus strain BC13. To reflect an applied system, the sorption of metal mixtures was also studied. In these experiments, lead, zinc, and copper sorption from a tertiary mixture were 40.2 ± 4.3%, 28.7 ± 3.8%, and 91.3 ± 3.0%, respectively, of that sorbed in single-metal systems.« less

A commercially viable virtual reality knee arthroscopy training system.

PubMed

McCarthy, A D; Hollands, R J

1998-01-01

Arthroscopy is a minimally invasive form of surgery used to inspect joints. It is complex to learn yet current training methods appear inadequate, thus negating the potential benefits to the patient. This paper describes the development and initial assessment of a cost-effective virtual reality based system for training surgeons in arthroscopy of the knee. The system runs on a P.C. Initial assessments by surgeons have been positive and current developments in deformable models are described.

Systems Biology Approach and Mathematical Modeling for Analyzing Phase-Space Switch During Epithelial-Mesenchymal Transition.

PubMed

Simeoni, Chiara; Dinicola, Simona; Cucina, Alessandra; Mascia, Corrado; Bizzarri, Mariano

2018-01-01

In this report, we aim at presenting a viable strategy for the study of Epithelial-Mesenchymal Transition (EMT) and its opposite Mesenchymal-Epithelial Transition (MET) by means of a Systems Biology approach combined with a suitable Mathematical Modeling analysis. Precisely, it is shown how the presence of a metastable state, that is identified at a mesoscopic level of description, is crucial for making possible the appearance of a phase transition mechanism in the framework of fast-slow dynamics for Ordinary Differential Equations (ODEs).

Flexibility and a Departmental Instructional Planning Model.

ERIC Educational Resources Information Center

Miner, Norris

The flexibility of an educational program, institution, or system can be described as the ability of the unit to absorb negative responses, such as reductions in funding or enrollments, and continue to function in a viable manner. One approach to adjustment to such reductions is to effect cuts in personnel, current, and equipment spending. This…

The Origin and Significance of the CCAM Line: Evidence from Chondrules and Dark Inclusions in Allende (CV3)

NASA Technical Reports Server (NTRS)

Greenwood, R. C.; Franchi, I. A.; Zolensky, M. E.; Buchanan, P. C.

2016-01-01

The process responsible for the mass independent oxygen isotope variation observed in Solar System materials remains poorly understood. While self-shielding of CO, either in the early solar nebula, or precursor molecular cloud, appears to be a viable mechanism, alternative models have also been proposed.

Peer Mentoring--Is a Virtual Form of Support a Viable Alternative?

ERIC Educational Resources Information Center

Smailes, Joanne; Gannon-Leary, Pat

2011-01-01

Support systems are vital for university entrants and one established means of support is peer mentoring, which has the potential to improve student engagement and retention. Peer mentoring models are generally based on face-to-face contact. However, given the increasing number of higher education institutions using social media, might online…

Developing integrated patient pathways using hybrid simulation

NASA Astrophysics Data System (ADS)

Zulkepli, Jafri; Eldabi, Tillal

2016-10-01

Integrated patient pathways includes several departments, i.e. healthcare which includes emergency care and inpatient ward; intermediate care which patient(s) will stay for a maximum of two weeks and at the same time be assessed by assessment team to find the most suitable care; and social care. The reason behind introducing the intermediate care in western countries was to reduce the rate of patients that stays in the hospital especially for elderly patients. This type of care setting has been considered to be set up in some other countries including Malaysia. Therefore, to assess the advantages of introducing this type of integrated healthcare setting, we suggest develop the model using simulation technique. We argue that single simulation technique is not viable enough to represent this type of patient pathways. Therefore, we suggest develop this model using hybrid techniques, i.e. System Dynamics (SD) and Discrete Event Simulation (DES). Based on hybrid model result, we argued that the result is viable to be as references for decision making process.

Life cycle cost analysis of a stand-alone PV system in rural Kenya

NASA Astrophysics Data System (ADS)

Daly, Emma

The purpose of this quantitative research study was to determine the economic feasibility of a stand-alone PV system to electrify a rural area in Kenya. The research conducted involved a comprehensive review of all the relevant literature associated with the study. Methodologies were extrapolated from this extensive literature to develop a model for the complete design and economic analysis of a stand-alone PV system. A women's center in rural Kenya was used as a worked example to demonstrate the workings of the model. The results suggest that electrifying the center using a stand-alone PV system is an economically viable option which is encouraging for the surrounding area. This model can be used as a business model to determine the economic feasibility of a stand-alone PV system in alternative sites in Kenya.

Computational models of an inductive power transfer system for electric vehicle battery charge

NASA Astrophysics Data System (ADS)

Anele, A. O.; Hamam, Y.; Chassagne, L.; Linares, J.; Alayli, Y.; Djouani, K.

2015-09-01

One of the issues to be solved for electric vehicles (EVs) to become a success is the technical solution of its charging system. In this paper, computational models of an inductive power transfer (IPT) system for EV battery charge are presented. Based on the fundamental principles behind IPT systems, 3 kW single phase and 22 kW three phase IPT systems for Renault ZOE are designed in MATLAB/Simulink. The results obtained based on the technical specifications of the lithium-ion battery and charger type of Renault ZOE show that the models are able to provide the total voltage required by the battery. Also, considering the charging time for each IPT model, they are capable of delivering the electricity needed to power the ZOE. In conclusion, this study shows that the designed computational IPT models may be employed as a support structure needed to effectively power any viable EV.

Development and Validation of a Bioreactor System for Dynamic Loading and Mechanical Characterization of Whole Human Intervertebral Discs in Organ Culture

PubMed Central

Walter, BA; Illien-Junger, S; Nasser, P; Hecht, AC; Iatridis, JC

2014-01-01

Intervertebral disc (IVD) degeneration is a common cause of back pain, and attempts to develop therapies are frustrated by lack of model systems that mimic the human condition. Human IVD organ culture models can address this gap, yet current models are limited since vertebral endplates are removed to maintain cell viability, physiological loading is not applied, and mechanical behaviors are not measured. This study aimed to (i) establish a method for isolating human IVDs from autopsy with intact vertebral endplates, and (ii) develop and validate an organ culture loading system for human or bovine IVDs. Human IVDs with intact endplates were isolated from cadavers within 48 hours of death and cultured for up to 21 days. IVDs remained viable with ~80% cell viability in nucleus and annulus regions. A dynamic loading system was designed and built with the capacity to culture 9 bovine or 6 human IVDs simultaneously while applying simulated physiologic loads (maximum force: 4kN) and measuring IVD mechanical behaviors. The loading system accurately applied dynamic loading regimes (RMS error <2.5N and total harmonic distortion <2.45%), and precisely evaluated mechanical behavior of rubber and bovine IVDs. Bovine IVDs maintained their mechanical behavior and retained >85% viable cells throughout the 3 week culture period. This organ culture loading system can closely mimic physiological conditions and be used to investigate response of living human and bovine IVDs to mechanical and chemical challenges and to screen therapeutic repair techniques. PMID:24725441

Fatigue loading of tendon

PubMed Central

Shepherd, Jennifer H; Screen, Hazel R C

2013-01-01

Tendon injuries, often called tendinopathies, are debilitating and painful conditions, generally considered to develop as a result of tendon overuse. The aetiology of tendinopathy remains poorly understood, and whilst tendon biopsies have provided some information concerning tendon appearance in late-stage disease, there is still little information concerning the mechanical and cellular events associated with disease initiation and progression. Investigating this in situ is challenging, and numerous models have been developed to investigate how overuse may generate tendon fatigue damage and how this may relate to tendinopathy conditions. This article aims to review these models and our current understanding of tendon fatigue damage. We review the strengths and limitations of different methodologies for characterizing tendon fatigue, considering in vitro methods that adopt both viable and non-viable samples, as well as the range of different in vivo approaches. By comparing data across model systems, we review the current understanding of fatigue damage development. Additionally, we compare these findings with data from tendinopathic tissue biopsies to provide some insights into how these models may relate to the aetiology of tendinopathy. Fatigue-induced damage consistently highlights the same microstructural, biological and mechanical changes to the tendon across all model systems and also correlates well with the findings from tendinopathic biopsy tissue. The multiple testing routes support matrix damage as an important contributor to tendinopathic conditions, but cellular responses to fatigue appear complex and often contradictory. PMID:23837793

Atmospheric Models for Aerocapture

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta L.; Keller, Vernon W.

2004-01-01

There are eight destinations in the solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithm, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan.

Using Future Research Methods in Analysing Policies Relating to Open Distance Education in Africa

ERIC Educational Resources Information Center

Makoe, Mpine Elizabeth

2018-01-01

Many African countries have developed policies to reform their education system in order to widen participation in higher education. To achieve this, open, online and distance education based models have been advocated as the most viable delivery tools in expanding access to higher education. However, the policy analysis of Kenya, Rwanda and…

The National Trust: A Viable Model of Care for Adults with Intellectual Disabilities in India

ERIC Educational Resources Information Center

Menon, Desh Keerti; Kishore, M. Thomas; Sivakumar, T.; Maulik, Pallab K.; Kumar, Devvarta; Lakhan, Ram; Banerjee, Ruma

2017-01-01

The longevity of people with intellectual disabilities is increasing in developing nations. However, developing nations lack a proper system of care for aging persons with intellectual disabilities. Until now the care has been provided by parents and relatives in the home environment in developing countries, but this scenario is also changing;…

Hybrid Hydro Renewable Energy Storage Model

NASA Astrophysics Data System (ADS)

Dey, Asit Kr

2018-01-01

This paper aims at presenting wind & tidal turbine pumped-storage solutions for improving the energy efficiency and economic sustainability of renewable energy systems. Indicated a viable option to solve problems of energy production, as well as in the integration of intermittent renewable energies, providing system flexibility due to energy load’s fluctuation, as long as the storage of energy from intermittent sources. Sea water storage energy is one of the best and most efficient options in terms of renewable resources as an integrated solution allowing the improvement of the energy system elasticity and the global system efficiency.

Quantification of viable and non-viable Legionella spp. by heterogeneous asymmetric recombinase polymerase amplification (haRPA) on a flow-based chemiluminescence microarray.

PubMed

Kober, Catharina; Niessner, Reinhard; Seidel, Michael

2018-02-15

Increasing numbers of legionellosis outbreaks within the last years have shown that Legionella are a growing challenge for public health. Molecular biological detection methods capable of rapidly identifying viable Legionella are important for the control of engineered water systems. The current gold standard based on culture methods takes up to 10 days to show positive results. For this reason, a flow-based chemiluminescence (CL) DNA microarray was developed that is able to quantify viable and non-viable Legionella spp. as well as Legionella pneumophila in one hour. An isothermal heterogeneous asymmetric recombinase polymerase amplification (haRPA) was carried out on flow-based CL DNA microarrays. Detection limits of 87 genomic units (GU) µL -1 and 26GUµL -1 for Legionella spp. and Legionella pneumophila, respectively, were achieved. In this work, it was shown for the first time that the combination of a propidium monoazide (PMA) treatment with haRPA, the so-called viability haRPA, is able to identify viable Legionella on DNA microarrays. Different proportions of viable and non-viable Legionella, shown with the example of L. pneumophila, ranging in a total concentration between 10 1 to 10 5 GUµL -1 were analyzed on the microarray analysis platform MCR 3. Recovery values for viable Legionella spp. were found between 81% and 133%. With the combination of these two methods, there is a chance to replace culture-based methods in the future for the monitoring of engineered water systems like condensation recooling plants. Copyright © 2017 Elsevier B.V. All rights reserved.

A viable logarithmic f(R) model for inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amin, M.; Khalil, S.; Salah, M.

2016-08-18

Inflation in the framework of f(R) modified gravity is revisited. We study the conditions that f(R) should satisfy in order to lead to a viable inflationary model in the original form and in the Einstein frame. Based on these criteria we propose a new logarithmic model as a potential candidate for f(R) theories aiming to describe inflation consistent with observations from Planck satellite (2015). The model predicts scalar spectral index 0.9615

Doi-Peliti path integral methods for stochastic systems with partial exclusion

NASA Astrophysics Data System (ADS)

Greenman, Chris D.

2018-09-01

Doi-Peliti methods are developed for stochastic models with finite maximum occupation numbers per site. We provide a generalized framework for the different Fock spaces reported in the literature. Paragrassmannian techniques are then utilized to construct path integral formulations of factorial moments. We show that for many models of interest, a Magnus expansion is required to construct a suitable action, meaning actions containing a finite number of terms are not always feasible. However, for such systems, perturbative techniques are still viable, and for some examples, including carrying capacity population dynamics, and diffusion with partial exclusion, the expansions are exactly summable.

A model for predicting Xanthomonas arboricola pv. pruni growth as a function of temperature

PubMed Central

Llorente, Isidre; Montesinos, Emilio; Moragrega, Concepció

2017-01-01

A two-step modeling approach was used for predicting the effect of temperature on the growth of Xanthomonas arboricola pv. pruni, causal agent of bacterial spot disease of stone fruit. The in vitro growth of seven strains was monitored at temperatures from 5 to 35°C with a Bioscreen C system, and a calibrating equation was generated for converting optical densities to viable counts. In primary modeling, Baranyi, Buchanan, and modified Gompertz equations were fitted to viable count growth curves over the entire temperature range. The modified Gompertz model showed the best fit to the data, and it was selected to estimate the bacterial growth parameters at each temperature. Secondary modeling of maximum specific growth rate as a function of temperature was performed by using the Ratkowsky model and its variations. The modified Ratkowsky model showed the best goodness of fit to maximum specific growth rate estimates, and it was validated successfully for the seven strains at four additional temperatures. The model generated in this work will be used for predicting temperature-based Xanthomonas arboricola pv. pruni growth rate and derived potential daily doublings, and included as the inoculum potential component of a bacterial spot of stone fruit disease forecaster. PMID:28493954

Estimation of Microbial Contamination of Food from Prevalence and Concentration Data: Application to Listeria monocytogenes in Fresh Vegetables▿

PubMed Central

Crépet, Amélie; Albert, Isabelle; Dervin, Catherine; Carlin, Frédéric

2007-01-01

A normal distribution and a mixture model of two normal distributions in a Bayesian approach using prevalence and concentration data were used to establish the distribution of contamination of the food-borne pathogenic bacteria Listeria monocytogenes in unprocessed and minimally processed fresh vegetables. A total of 165 prevalence studies, including 15 studies with concentration data, were taken from the scientific literature and from technical reports and used for statistical analysis. The predicted mean of the normal distribution of the logarithms of viable L. monocytogenes per gram of fresh vegetables was −2.63 log viable L. monocytogenes organisms/g, and its standard deviation was 1.48 log viable L. monocytogenes organisms/g. These values were determined by considering one contaminated sample in prevalence studies in which samples are in fact negative. This deliberate overestimation is necessary to complete calculations. With the mixture model, the predicted mean of the distribution of the logarithm of viable L. monocytogenes per gram of fresh vegetables was −3.38 log viable L. monocytogenes organisms/g and its standard deviation was 1.46 log viable L. monocytogenes organisms/g. The probabilities of fresh unprocessed and minimally processed vegetables being contaminated with concentrations higher than 1, 2, and 3 log viable L. monocytogenes organisms/g were 1.44, 0.63, and 0.17%, respectively. Introducing a sensitivity rate of 80 or 95% in the mixture model had a small effect on the estimation of the contamination. In contrast, introducing a low sensitivity rate (40%) resulted in marked differences, especially for high percentiles. There was a significantly lower estimation of contamination in the papers and reports of 2000 to 2005 than in those of 1988 to 1999 and a lower estimation of contamination of leafy salads than that of sprouts and other vegetables. The interest of the mixture model for the estimation of microbial contamination is discussed. PMID:17098926

Economic analysis of model validation for a challenge problem

DOE PAGES

Paez, Paul J.; Paez, Thomas L.; Hasselman, Timothy K.

2016-02-19

It is now commonplace for engineers to build mathematical models of the systems they are designing, building, or testing. And, it is nearly universally accepted that phenomenological models of physical systems must be validated prior to use for prediction in consequential scenarios. Yet, there are certain situations in which testing only or no testing and no modeling may be economically viable alternatives to modeling and its associated testing. This paper develops an economic framework within which benefit–cost can be evaluated for modeling and model validation relative to other options. The development is presented in terms of a challenge problem. Asmore » a result, we provide a numerical example that quantifies when modeling, calibration, and validation yield higher benefit–cost than a testing only or no modeling and no testing option.« less

Model-centric approaches for the development of health information systems.

PubMed

Tuomainen, Mika; Mykkänen, Juha; Luostarinen, Heli; Pöyhölä, Assi; Paakkanen, Esa

2007-01-01

Modeling is used increasingly in healthcare to increase shared knowledge, to improve the processes, and to document the requirements of the solutions related to health information systems (HIS). There are numerous modeling approaches which aim to support these aims, but a careful assessment of their strengths, weaknesses and deficiencies is needed. In this paper, we compare three model-centric approaches in the context of HIS development: the Model-Driven Architecture, Business Process Modeling with BPMN and BPEL and the HL7 Development Framework. The comparison reveals that all these approaches are viable candidates for the development of HIS. However, they have distinct strengths and abstraction levels, they require local and project-specific adaptation and offer varying levels of automation. In addition, illustration of the solutions to the end users must be improved.

Kinetics of killing Listeria monocytogenes by macrophages: correlation of /sup 3/H-DNA release from labeled bacteria and changes in numbers of viable organisms by mathematical model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davies, W.A.

1982-12-01

Conventional methods of assessing antibacterial activities of macrophages by viable counting are limited by the precision of the statistics and are difficult to interpret quantitatively because of unrestrained extracellular growth of bacteria. An alternative technique based on the release of radioactive DNA from labeled bacteria has been offered as overcoming these drawbacks. To assess it for use with macrophages I have made a correlation with the conventional viable counting method using a mathematical model. Opsonized Listeria monocytogenes labeled with /sup 3/H-thymidine were exposed to rat macrophages for periods up to 4 hr. Numbers of viable bacteria determined after sonication increasedmore » exponentially in the absence of live cells and this growth rate was progressively inhibited by increasing numbers of macrophages. After a lag period of 30-60 min soluble /sup 3/H appeared in the supernatant, the amount increasing with time and numbers of macrophages. To correlate these data I developed a mathematical model that considered that changes in numbers of viable organisms were due to the difference between rates of 1) growth of extracellular bacteria and 2) killing within the macrophage. On the basis of this model curves of best fit to the viable counts data were used to predict the release of radioactivity, assuming that death of a bacterium led to the total release of its label. These predictions and the experimental data agreed well, the lag period of 30-60 min between death of the bacterium and release of radioactivity being consistent with intracellular digestion. Release of soluble radioactivity appears to be an accurate reflection of the number of bacteria killed within the macrophage.« less

Bacteriophage treatment significantly reduces viable Clostridium difficile and prevents toxin production in an in vitro model system.

PubMed

Meader, Emma; Mayer, Melinda J; Gasson, Michael J; Steverding, Dietmar; Carding, Simon R; Narbad, Arjan

2010-12-01

Clostridium difficile is primarily a nosocomial pathogen, causing thousands of cases of antibiotic-associated diarrhoea in the UK each year. In this study, we used a batch fermentation model of a C. difficile colonised system to evaluate the potential of a prophylactic and a remedial bacteriophage treatment regime to control the pathogen. It is shown that the prophylaxis regime was effective at preventing the growth of C. difficile (p = <0.001) and precluded the production of detectable levels of toxins A and B. The remedial treatment regime caused a less profound and somewhat transient decrease in the number of viable C. difficile cells (p = <0.0001), but still resulted in a lower level of toxin production relative to the control. The numbers of commensal bacteria including total aerobes and anaerobes, Bifidobacterium sp., Bacteroides sp., Lactobacillus sp., total Clostridium sp., and Enterobacteriaceae were not significantly decreased by this therapy, whereas significant detrimental effects were observed with metronidazole treatment. Our study indicates that phage therapy has potential to be used for the control of C. difficile; it highlights the main benefits of this approach, and some future challenges. Copyright © 2010 Elsevier Ltd. All rights reserved.

Facility Will Help Transition Models Into Operations

NASA Astrophysics Data System (ADS)

Kumar, Mohi

2009-02-01

The U.S. National Oceanic and Atmospheric Administration's Space Weather Prediction Center (NOAA SWPC), in partnership with the U.S. Air Force Weather Agency (AFWA), is establishing a center to promote and facilitate the transition of space weather models to operations. The new facility, called the Developmental Testbed Center (DTC), will take models used by researchers and rigorously test them to see if they can withstand continued use as viable warning systems. If a model used in a space weather warning system crashes or fails to perform well, severe consequences can result. These include increased radiation risks to astronauts and people traveling on high-altitude flights, national security vulnerabilities from the loss of military satellite communications, and the cost of replacing damaged military and commercial spacecraft.

Cosmological constraints and comparison of viable f (R ) models

NASA Astrophysics Data System (ADS)

Pérez-Romero, Judit; Nesseris, Savvas

2018-01-01

In this paper we present cosmological constraints on several well-known f (R ) models, but also on a new class of models that are variants of the Hu-Sawicki one of the form f (R )=R -2/Λ 1 +b y (R ,Λ ) , that interpolate between the cosmological constant model and a matter dominated universe for different values of the parameter b , which is usually expected to be small for viable models and which in practice measures the deviation from general relativity. We use the latest growth rate, cosmic microwave background, baryon acoustic oscillations, supernovae type Ia and Hubble parameter data to place stringent constraints on the models and to compare them to the cosmological constant model but also other viable f (R ) models such as the Starobinsky or the degenerate hypergeometric models. We find that these kinds of Hu-Sawicki variant parametrizations are in general compatible with the currently available data and can provide useful toy models to explore the available functional space of f (R ) models, something very useful with the current and upcoming surveys that will test deviations from general relativity.

Propulsion Investigation for Zero and Near-Zero Emissions Aircraft

NASA Technical Reports Server (NTRS)

Snyder, Christopher A.; Berton, Jeffrey J.; Brown, Gerald v.; Dolce, James L.; Dravid, Marayan V.; Eichenberg, Dennis J.; Freeh, Joshua E.; Gallo, Christopher A.; Jones, Scott M.; Kundu, Krishna P.;

Economic and financial viability of small-scale dairy systems in central Mexico: economic scenario 2010-2018.

PubMed

Posadas-Domínguez, R R; Callejas-Juárez, N; Arriaga-Jordán, C M; Martínez-Castañeda, F E

2016-12-01

A simulation Monte Carlo model was used to assess the economic and financial viability of 130 small-scale dairy farms in central Mexico, through a Representative Small-Scale Dairy Farm. Net yields were calculated for a 9-year planning horizon by means of simulated values for the distribution of input and product prices taking 2010 as base year and considering four scenarios which were compared against the scenario of actual production. The other scenarios were (1) total hiring in of needed labour; (2) external purchase of 100 % of inputs and (3) withdrawal of subsidies to production. A stochastic modelling approach was followed to determine the scenario with the highest economic and financial viability. Results show a viable economic and financial situation for the real production scenario, as well as the scenarios for total hiring of labour and of withdrawal of subsidies, but the scenario when 100 % of feed inputs for the herd are bought-in was not viable.

Non-Destructive Quality Evaluation of Pepper (Capsicum annuum L.) Seeds Using LED-Induced Hyperspectral Reflectance Imaging

PubMed Central

Mo, Changyeun; Kim, Giyoung; Lee, Kangjin; Kim, Moon S.; Cho, Byoung-Kwan; Lim, Jongguk; Kang, Sukwon

2014-01-01

In this study, we developed a viability evaluation method for pepper (Capsicum annuum L.) seeds based on hyperspectral reflectance imaging. The reflectance spectra of pepper seeds in the 400–700 nm range are collected from hyperspectral reflectance images obtained using blue, green, and red LED illumination. A partial least squares–discriminant analysis (PLS-DA) model is developed to classify viable and non-viable seeds. Four spectral ranges generated with four types of LEDs (blue, green, red, and RGB), which were pretreated using various methods, are investigated to develop the classification models. The optimal PLS-DA model based on the standard normal variate for RGB LED illumination (400–700 nm) yields discrimination accuracies of 96.7% and 99.4% for viable seeds and nonviable seeds, respectively. The use of images based on the PLS-DA model with the first-order derivative of a 31.5-nm gap for red LED illumination (600–700 nm) yields 100% discrimination accuracy for both viable and nonviable seeds. The results indicate that a hyperspectral imaging technique based on LED light can be potentially applied to high-quality pepper seed sorting. PMID:24763251

Non-destructive quality evaluation of pepper (Capsicum annuum L.) seeds using LED-induced hyperspectral reflectance imaging.

PubMed

Mo, Changyeun; Kim, Giyoung; Lee, Kangjin; Kim, Moon S; Cho, Byoung-Kwan; Lim, Jongguk; Kang, Sukwon

2014-04-24

In this study, we developed a viability evaluation method for pepper (Capsicum annuum L.) seeds based on hyperspectral reflectance imaging. The reflectance spectra of pepper seeds in the 400-700 nm range are collected from hyperspectral reflectance images obtained using blue, green, and red LED illumination. A partial least squares-discriminant analysis (PLS-DA) model is developed to classify viable and non-viable seeds. Four spectral ranges generated with four types of LEDs (blue, green, red, and RGB), which were pretreated using various methods, are investigated to develop the classification models. The optimal PLS-DA model based on the standard normal variate for RGB LED illumination (400-700 nm) yields discrimination accuracies of 96.7% and 99.4% for viable seeds and nonviable seeds, respectively. The use of images based on the PLS-DA model with the first-order derivative of a 31.5-nm gap for red LED illumination (600-700 nm) yields 100% discrimination accuracy for both viable and nonviable seeds. The results indicate that a hyperspectral imaging technique based on LED light can be potentially applied to high-quality pepper seed sorting.

Stability issues of nonlocal gravity during primordial inflation

NASA Astrophysics Data System (ADS)

Belgacem, Enis; Cusin, Giulia; Foffa, Stefano; Maggiore, Michele; Mancarella, Michele

2018-01-01

We study the cosmological evolution of some nonlocal gravity models, when the initial conditions are set during a phase of primordial inflation. We examine in particular three models, the so-called RT, RR and Δ4 models, previously introduced by our group. We find that, during inflation, the RT model has a viable background evolution, but at the level of cosmological perturbations develops instabilities that make it nonviable. In contrast, the RR and Δ4 models have a viable evolution even when their initial conditions are set during a phase of primordial inflation.

Renewable Hydrogen-Economically Viable: Integration into the U.S. Transportation Sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurtz, Jennifer; Peters, Mike; Muratori, Matteo

The U.S. transportation sector is expected to meet numerous goals in differing applications. These goals address security, safety, fuel source, emissions reductions, advanced mobility models, and improvements in quality and accessibility. Solutions to meeting these goals include a variety of alternative-fuel technologies, including batteries, fuel cells, synthetic fuels, and biofuels, as well as modifying how current transportation systems are used and integrating new systems, such as storing renewable energy. Overall, there are many combinations of problems, objectives, and solutions.

Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa

PubMed Central

Coulthard, Tom J.; Ramirez, Jorge A.; Barton, Nick; Rogerson, Mike; Brücher, Tim

2013-01-01

Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times. PMID:24040347

A novel microfluidic platform for size and deformability based separation and the subsequent molecular characterization of viable circulating tumor cells.

PubMed

Hvichia, G E; Parveen, Z; Wagner, C; Janning, M; Quidde, J; Stein, A; Müller, V; Loges, S; Neves, R P L; Stoecklein, N H; Wikman, H; Riethdorf, S; Pantel, K; Gorges, T M

2016-06-15

Circulating tumor cells (CTCs) were introduced as biomarkers more than 10 years ago, but capture of viable CTCs at high purity from peripheral blood of cancer patients is still a major technical challenge. Here, we report a novel microfluidic platform designed for marker independent capture of CTCs. The Parsortix™ cell separation system provides size and deformability-based enrichment with automated staining for cell identification, and subsequent recovery (harvesting) of cells from the device. Using the Parsortix™ system, average cell capture inside the device ranged between 42% and 70%. Subsequent harvest of cells from the device ranged between 54% and 69% of cells captured. Most importantly, 99% of the isolated tumor cells were viable after processing in spiking experiments as well as after harvesting from patient samples and still functional for downstream molecular analysis as demonstrated by mRNA characterization and array-based comparative genomic hybridization. Analyzing clinical blood samples from metastatic (n = 20) and nonmetastatic (n = 6) cancer patients in parallel with CellSearch(®) system, we found that there was no statistically significant difference between the quantitative behavior of the two systems in this set of twenty six paired separations. In conclusion, the epitope independent Parsortix™ system enables the isolation of viable CTCs at a very high purity. Using this system, viable tumor cells are easily accessible and ready for molecular and functional analysis. The system's ability for enumeration and molecular characterization of EpCAM-negative CTCs will help to broaden research into the mechanisms of cancer as well as facilitating the use of CTCs as "liquid biopsies." © 2016 The Authors International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.

Progress Towards the Vindication of Panspermia

NASA Astrophysics Data System (ADS)

Wickramasinghe, N. C.; Wainwright, M.; Narlikar, J. V.; Rajaratnam, P.; Harris, M. J.; Lloyd, D.

Theories of panspermia are rapidly coming into vogue, with the possibility of the transfer of viable bacterial cells from one planetary abode to another being generally accepted as inevitable. The panspermia models of Hoyle and Wickramasinghe require the transfer of viable bacterial cells from interstellar dust to comets and back into interplanetary and interstellar space. In such a cycle a viable fraction of as little as 10-18 at the inception of a newly formed comet/planet system suffices for cometary panspermia to dominate over competing processes for the origin and transfer of life. The well-attested survival attributes of microbes under extreme conditions, which have recently been discovered, gives credence to the panspermia hypothesis. The prediction of the theory that comets bring microbes onto the Earth at the present time is testable if aseptic collections of stratospheric air above the tropopause can be obtained. We describe a recent collection of this kind and report microbiological analysis that shows the existence of viable cells at 41km, falling to Earth at the rate of a few tonnes per day over the entire globe. Some of these cells have been cultured in the laboratory and found to include microorganisms that are not too different from related species on the Earth. This is in fact what the Hoyle-Wickramasinghe theory predicts. The weight of evidence goes against the more conservative explanation that organisms are being lofted to the high atmosphere from the ground.

Preventing Pirates from Boarding Commercial Vessels - A Systems Approach

DTIC Science & Technology

2014-09-01

was developed in MATLAB to run simulations designed to estimate the relative effectiveness of each assessed countermeasure. A cost analysis was...project indicated that the P-Trap countermeasure, designed to entangle the pirate’s propellers with thin lines, is both effective and economically viable...vessels. A model of the operational environment was developed in MATLAB to run simulations designed to estimate the relative effectiveness of each

On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study

PubMed Central

Boto, Elena; Bowtell, Richard; Krüger, Peter; Fromhold, T. Mark; Morris, Peter G.; Meyer, Sofie S.; Barnes, Gareth R.; Brookes, Matthew J.

2016-01-01

Magnetoencephalography (MEG) is a sophisticated tool which yields rich information on the spatial, spectral and temporal signatures of human brain function. Despite unique potential, MEG is limited by a low signal-to-noise ratio (SNR) which is caused by both the inherently small magnetic fields generated by the brain, and the scalp-to-sensor distance. The latter is limited in current systems due to a requirement for pickup coils to be cryogenically cooled. Recent work suggests that optically-pumped magnetometers (OPMs) might be a viable alternative to superconducting detectors for MEG measurement. They have the advantage that sensors can be brought to within ~4 mm of the scalp, thus offering increased sensitivity. Here, using simulations, we quantify the advantages of hypothetical OPM systems in terms of sensitivity, reconstruction accuracy and spatial resolution. Our results show that a multi-channel whole-head OPM system offers (on average) a fivefold improvement in sensitivity for an adult brain, as well as clear improvements in reconstruction accuracy and spatial resolution. However, we also show that such improvements depend critically on accurate forward models; indeed, the reconstruction accuracy of our simulated OPM system only outperformed that of a simulated superconducting system in cases where forward field error was less than 5%. Overall, our results imply that the realisation of a viable whole-head multi-channel OPM system could generate a step change in the utility of MEG as a means to assess brain electrophysiological activity in health and disease. However in practice, this will require both improved hardware and modelling algorithms. PMID:27564416

Atmospheric Models for Aerocapture

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duval, Aleta; Keller, Vernon W.

2003-01-01

There are eight destinations in the Solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Robe entry at Titan, are discussed. Recent updates to the Mars atmospheric model, in support of ongoing Mars aerocapture systems analysis studies, are also presented.

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents.

PubMed

O'Donnell, David; Sperzel, Johannes; Thibault, Bernard; Rinaldi, Christopher A; Pappone, Carlo; Gutleben, Klaus-Jürgen; Leclercq, Christopher; Razavi, Hedi; Ryu, Kyungmoo; Mcspadden, Luke C; Fischer, Avi; Tomassoni, Gery

2017-04-01

The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT). A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355). Bipolar and tripolar lead configurations were modelled by systematic elimination of two and one electrode(s), respectively, from the Quartet lead. The Quartet lead with its four pacing electrodes exhibited the greatest number of pacing vectors per patient when compared with the best bipolar and the best tripolar modelled equivalents. Similarly, the Quartet lead provided the highest spatial coverage in terms of the distance between two furthest viable pacing cathodes when compared with the best bipolar and the best tripolar configurations (P < 0.05). Among the three modelled bipolar configurations, the lead configuration with the two most distal electrodes resulted in the highest number of viable pacing vectors. Among the four modelled tripolar configurations, elimination of the second proximal electrode (M3) resulted in the highest number of viable pacing options per patient. There were no significant differences observed between pre-discharge and first follow-up analyses. The Quartet lead with its four electrodes and the capability to pace from four anatomical locations provided the highest number of viable pacing vectors at pre-discharge and first follow-up visits, providing more flexibility in device programming and enabling continuation of CRT in more patients when compared with bipolar and tripolar equivalents. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Angiotensin II improves random-flap viability in a rat model.

PubMed

Okuyama, N; Roda, N; Sherman, R; Guerrero, A; Dougherty, W; Nguyen, T; diZerega, G; Rodgers, K

1999-03-01

Angiotensin II (AII) is a naturally occurring peptide that has been shown to be angiogenic, cause the proliferation of several primary cell types (including endothelial cells), accelerate the repair of dermal injuries, and increase production of growth factors and extracellular matrix. The effect of a single administration of AII on the viability and vascularity of a random flap was assessed in a rat model. In the control model, the viability of the distal portion of the flap was reduced consistently by postoperative day 8. Initially, AII was administered in an aqueous vehicle (phosphate-buffered saline [PBS]) and a viscous vehicle (10% carboxymethyl cellulose [CMC]). Administration of 1 mg per milliliter AII in PBS did not affect the viability of random flaps (1.2 x 7 cm) in this animal model. However, a single administration of a higher dose of AII in PBS (10 mg per milliliter) or 1 mg per milliliter AII in the CMC vehicle resulted in 67% of the grafts being fully viable at postsurgical day 12, in contrast to vehicle-treated control flaps, none of which were fully viable at day 12. Furthermore, the portion of the flap that was viable was increased significantly (p < or = 0.05). Subsequently, a study was conducted to assess the dose-response curve for AII in a CMC vehicle in this rat model. As the dose of AII was reduced, the percentage of animals with fully viable flaps and the percentage of the flap that was viable decreased correspondingly. Administration of 0.03 mg per milliliter AII and greater increased significantly (p < or = 0.05) the viability of the flaps. In conclusion, AII appears to be highly efficacious in increasing the percentage of distal flap surface area survival when administered as a single topical dose to the wound bed.

Use of a grid simulation model for longer-term analysis of wind energy integration

NASA Astrophysics Data System (ADS)

Bossanyi, E.

A simulation model of an electricity generating system is used to study the integration of wind energy onto the system. Most of the system cost savings achieved are due to the savings of fossil fuels, but in the long term additional savings result from re-optimization of the plant mix. Break-even costs are calculated for wind turbines to become economically viable as fossil fuel savers. This allows the optimum economic penetration level for wind turbines of any given cost to be derived. Break-even costs up to reasonably large penetrations appear to be within reach with modern technology. Results are also given with scenarios of increasing fossil fuel prices and increased nuclear capacity.

Advantages of using the CRISPR/Cas9 system of genome editing to investigate male reproductive mechanisms using mouse models.

PubMed

Young, Samantha A M; Aitken, R John; Ikawa, Masahito

2015-01-01

Gene disruption technology has long been beneficial for the study of male reproductive biology. However, because of the time and cost involved, this technology was not a viable method except in specialist laboratories. The advent of the CRISPR/Cas9 system of gene disruption has ushered in a new era of genetic investigation. Now, it is possible to generate gene-disrupted mouse models in very little time and at very little cost. This Highlight article discusses the application of this technology to study the genetics of male fertility and looks at some of the future uses of this system that could be used to reveal the essential and nonessential genetic components of male reproductive mechanisms.

Removal of metal from acid mine drainage using a hybrid system including a pipes inserted microalgae reactor.

PubMed

Park, Young-Tae; Lee, Hongkyun; Yun, Hyun-Shik; Song, Kyung-Guen; Yeom, Sung-Ho; Choi, Jaeyoung

2013-12-01

In this study, the microalgae culture system to combined active treatment system and pipe inserted microalgae reactor (PIMR) was investigated. After pretreated AMD in active treatment system, the effluent load to PIMR in order to Nephroselmis sp. KGE 8 culture. In experiment, effect of iron on growth and lipid accumulation in microalgae were inspected. The 2nd pretreatment effluent was economic feasibility of microalgae culture and lipid accumulation. The growth kinetics of the microalgae are modeled using logistic growth model and the model is primarily parameterized from data obtained through an experimental study where PIMR were dosed with BBM, BBM added 10 mg L(-1) iron and 2nd pretreatment effluent. Moreover, the continuous of microalgae culture in PIMR can be available. Overall, this study indicated that the use of pretreated AMD is a viable method for culture microalgae and lipid accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Creating a library holding group: an approach to large system integration.

PubMed

Huffman, Isaac R; Martin, Heather J; Delawska-Elliott, Basia

2016-10-01

Faced with resource constraints, many hospital libraries have considered joint operations. This case study describes how Providence Health & Services created a single group to provide library services. Using a holding group model, staff worked to unify more than 6,100 nonlibrary subscriptions and 14 internal library sites. Our library services grew by unifying 2,138 nonlibrary subscriptions and 11 library sites and hiring more library staff. We expanded access to 26,018 more patrons. A model with built-in flexibility allowed successful library expansion. Although challenges remain, this success points to a viable model of unified operations.

Airport emissions quantification: Impacts of electrification. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geba, V.

1998-07-01

Four airports were assessed to demonstrate that electrification of economically viable air- and land-side vehicles and equipment can significantly reduce total airport emissions. Assessments were made using the FAA`s Emissions and Dispersion Modeling System and EPRI Airport Electrification Project data. Development and implementation of cost-effective airport emissions reduction strategies can be complex, requiring successful collaboration of local, state, and federal regulatory agencies with airport authorities. The methodology developed in this study helps to simplify this task. The objectives of this study were: to develop a methodology to quantify annual emissions at US airports from all sources--aircraft, vehicles, and infrastructure; andmore » to demonstrate that electrification of economically viable air- and land-side vehicles and equipment can significantly reduce total airport emissions on-site, even when allowing for emissions from the generation of electricity.« less

Finding viable models in SUSY parameter spaces with signal specific discovery potential

NASA Astrophysics Data System (ADS)

Burgess, Thomas; Lindroos, Jan Øye; Lipniacka, Anna; Sandaker, Heidi

2013-08-01

Recent results from ATLAS giving a Higgs mass of 125.5 GeV, further constrain already highly constrained supersymmetric models such as pMSSM or CMSSM/mSUGRA. As a consequence, finding potentially discoverable and non-excluded regions of model parameter space is becoming increasingly difficult. Several groups have invested large effort in studying the consequences of Higgs mass bounds, upper limits on rare B-meson decays, and limits on relic dark matter density on constrained models, aiming at predicting superpartner masses, and establishing likelihood of SUSY models compared to that of the Standard Model vis-á-vis experimental data. In this paper a framework for efficient search for discoverable, non-excluded regions of different SUSY spaces giving specific experimental signature of interest is presented. The method employs an improved Markov Chain Monte Carlo (MCMC) scheme exploiting an iteratively updated likelihood function to guide search for viable models. Existing experimental and theoretical bounds as well as the LHC discovery potential are taken into account. This includes recent bounds on relic dark matter density, the Higgs sector and rare B-mesons decays. A clustering algorithm is applied to classify selected models according to expected phenomenology enabling automated choice of experimental benchmarks and regions to be used for optimizing searches. The aim is to provide experimentalist with a viable tool helping to target experimental signatures to search for, once a class of models of interest is established. As an example a search for viable CMSSM models with τ-lepton signatures observable with the 2012 LHC data set is presented. In the search 105209 unique models were probed. From these, ten reference benchmark points covering different ranges of phenomenological observables at the LHC were selected.

Light Z' in heterotic string standardlike models

NASA Astrophysics Data System (ADS)

Athanasopoulos, P.; Faraggi, A. E.; Mehta, V. M.

2014-05-01

The discovery of the Higgs boson at the LHC supports the hypothesis that the Standard Model provides an effective parametrization of all subatomic experimental data up to the Planck scale. String theory, which provides a viable perturbative approach to quantum gravity, requires for its consistency the existence of additional gauge symmetries beyond the Standard Model. The construction of heterotic string models with a viable light Z' is, however, highly constrained. We outline the construction of standardlike heterotic string models that allow for an additional Abelian gauge symmetry that may remain unbroken down to low scales. We present a string inspired model, consistent with the string constraints.

Thermal modeling of step-out targets at the Soda Lake geothermal field, Churchill County, Nevada

NASA Astrophysics Data System (ADS)

Dingwall, Ryan Kenneth

Temperature data at the Soda Lake geothermal field in the southeastern Carson Sink, Nevada, highlight an intense thermal anomaly. The geothermal field produces roughly 11 MWe from two power producing facilities which are rated to 23 MWe. The low output is attributed to the inability to locate and produce sufficient volumes of fluid at adequate temperature. Additionally, the current producing area has experienced declining production temperatures over its 40 year history. Two step-out targets adjacent to the main field have been identified that have the potential to increase production and extend the life of the field. Though shallow temperatures in the two subsidiary areas are significantly less than those found within the main anomaly, measurements in deeper wells (>1,000 m) show that temperatures viable for utilization are present. High-pass filtering of the available complete Bouguer gravity data indicates that geothermal flow is present within the shallow sediments of the two subsidiary areas. Significant faulting is observed in the seismic data in both of the subsidiary areas. These structures are highlighted in the seismic similarity attribute calculated as part of this study. One possible conceptual model for the geothermal system(s) at the step-out targets indicated upflow along these faults from depth. In order to test this hypothesis, three-dimensional computer models were constructed in order to observe the temperatures that would result from geothermal flow along the observed fault planes. Results indicate that the observed faults are viable hosts for the geothermal system(s) in the step-out areas. Subsequently, these faults are proposed as targets for future exploration focus and step-out drilling.

EMISSION EXPOSURE MODEL FOR TRANSPORT OF TOXIC MOLD

EPA Science Inventory

The paper presents the results of a study of the release of Stachybotrys chartarum spores from contaminated gypsum wallboard and of tests on the effects of environmental conditions on the release of viable and non-viable spores and fragments. Biocontaminants such as mold spores a...

NASA Tech Briefs, September 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures; Multi-Axis Accelerometer Calibration System; Pupil Alignment Measuring Technique and Alignment Reference for Instruments or Optical Systems; Autonomous System for Monitoring the Integrity of Composite Fan Housings; A Safe, Self-Calibrating, Wireless System for Measuring Volume of Any Fuel at Non-Horizontal Orientation; Adaptation of the Camera Link Interface for Flight-Instrument Applications; High-Performance CCSDS Encapsulation Service Implementation in FPGA; High-Performance CCSDS AOS Protocol Implementation in FPGA; Advanced Flip Chips in Extreme Temperature Environments; Diffuse-Illumination Systems for Growing Plants; Microwave Plasma Hydrogen Recovery System; Producing Hydrogen by Plasma Pyrolysis of Methane; Self-Deployable Membrane Structures; Reactivation of a Tin-Oxide-Containing Catalys; Functionalization of Single-Wall Carbon Nanotubes by Photo-Oxidation; Miniature Piezoelectric Macro-Mass Balance; Acoustic Liner for Turbomachinery Applications; Metering Gas Strut for Separating Rocket Stages; Large-Flow-Area Flow-Selective Liquid/Gas Separator; Counterflowing Jet Subsystem Design; Water Tank with Capillary Air/Liquid Separation; True Shear Parallel Plate Viscometer; Focusing Diffraction Grating Element with Aberration Control; Universal Millimeter-Wave Radar Front End; Mode Selection for a Single-Frequency Fiber Laser; Qualification and Selection of Flight Diode Lasers for Space Applications; Plenoptic Imager for Automated Surface Navigation; Maglev Facility for Simulating Variable Gravity; Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection; High-Speed Operation of Interband Cascade Lasers; 3D GeoWall Analysis System for Shuttle External Tank Foreign Object Debris Events; Charge-Spot Model for Electrostatic Forces in Simulation of Fine Particulates; Hidden Statistics Approach to Quantum Simulations; Reconstituted Three-Dimensional Interactive Imaging; Determining Atmospheric-Density Profile of Titan; Digital Microfluidics Sample Analyzer; Radiation Protection Using Carbon Nanotube Derivatives; Process to Selectively Distinguish Viable from Non-Viable Bacterial Cells; and TEAMS Model Analyzer.

An Analysis of Viable Financial Negotiations Processes and Related Internal Controls for Procurement in Pakistan

DTIC Science & Technology

2016-06-01

regulations are in accordance with UNCITRAL Model Law and are based on principles of “ accountability , transparency, fairness, efficiency and value for... account certain factors about the firm(s) for pre-qualification. These factors include past performance and experience; financial health; managerial...internal control components, along with associated principles , were discussed in detail to develop a suitable internal control system for the financial

Advanced Analysis to Distinguish between Physical Decrease and Inactivation of Viable Phages in Aerosol by Quantitating Phage-Specific Particles.

PubMed

Shimasaki, Noriko; Nojima, Yasuhiro; Sakakibara, Masaya; Kikuno, Ritsuko; Iizuka, Chiori; Okaue, Akira; Okuda, Shunji; Shinohara, Katsuaki

2018-01-01

　Recent studies have investigated the efficacy of air-cleaning products against pathogens in the air. A standard method to evaluate the reduction in airborne viruses caused by an air cleaner has been established using a safe bacteriophage instead of pathogenic viruses; the reduction in airborne viruses is determined by counting the number of viable airborne phages by culture, after operating the air cleaner. The reduction in the number of viable airborne phages could be because of "physical decrease" or "inactivation". Therefore, to understand the mechanism of reduction correctly, an analysis is required to distinguish between physical decrease and inactivation. The purpose of this study was to design an analysis to distinguish between the physical decrease and inactivation of viable phi-X174 phages in aerosols. We established a suitable polymerase chain reaction (PCR) system by selecting an appropriate primer-probe set for PCR and validating the sensitivity, linearity, and specificity of the primer-probe set to robustly quantify phi-X174-specific airborne particles. Using this quantitative PCR system and culture assay, we performed a behavior analysis of the phage aerosol in a small chamber (1 m 3 ) at different levels of humidity, as humidity is known to affect the number of viable airborne phages. The results revealed that the reduction in the number of viable airborne phages was caused not only by physical decrease but also by inactivation under particular levels of humidity. Our study could provide an advanced analysis to differentiate between the physical decrease and inactivation of viable airborne phages.

A zebrafish larval model reveals early tissue-specific innate immune responses to Mucor circinelloides.

PubMed

Voelz, Kerstin; Gratacap, Remi L; Wheeler, Robert T

2015-11-01

Mucormycosis is an emerging fungal infection that is clinically difficult to manage, with increasing incidence and extremely high mortality rates. Individuals with diabetes, suppressed immunity or traumatic injury are at increased risk of developing disease. These individuals often present with defects in phagocytic effector cell function. Research using mammalian models and phagocytic effector cell lines has attempted to decipher the importance of the innate immune system in host defence against mucormycosis. However, these model systems have not been satisfactory for direct analysis of the interaction between innate immune effector cells and infectious sporangiospores in vivo. Here, we report the first real-time in vivo analysis of the early innate immune response to mucormycete infection using a whole-animal zebrafish larval model system. We identified differential host susceptibility, dependent on the site of infection (hindbrain ventricle and swim bladder), as well as differential functions of the two major phagocyte effector cell types in response to viable and non-viable spores. Larval susceptibility to mucormycete spore infection was increased upon immunosuppressant treatment. We showed for the first time that macrophages and neutrophils were readily recruited in vivo to the site of infection in an intact host and that spore phagocytosis can be observed in real-time in vivo. While exploring innate immune effector recruitment dynamics, we discovered the formation of phagocyte clusters in response to fungal spores that potentially play a role in fungal spore dissemination. Spores failed to activate pro-inflammatory gene expression by 6 h post-infection in both infection models. After 24 h, induction of a pro-inflammatory response was observed only in hindbrain ventricle infections. Only a weak pro-inflammatory response was initiated after spore injection into the swim bladder during the same time frame. In the future, the zebrafish larva as a live whole-animal model system will contribute greatly to the study of molecular mechanisms involved in the interaction of the host innate immune system with fungal spores during mucormycosis. © 2015. Published by The Company of Biologists Ltd.

Removal of viable bioaerosol particles with a low-efficiency HVAC filter enhanced by continuous emission of unipolar air ions.

PubMed

Huang, R; Agranovski, I; Pyankov, O; Grinshpun, S

2008-04-01

Continuous emission of unipolar ions has been shown to improve the performance of respirators and stationary filters challenged with non-biological particles. In this study, we investigated the ion-induced enhancement effect while challenging a low-efficiency heating, ventilation and air-conditioning (HVAC) filter with viable bacterial cells, bacterial and fungal spores, and viruses. The aerosol concentration was measured in real time. Samples were also collected with a bioaerosol sampler for viable microbial analysis. The removal efficiency of the filter was determined, respectively, with and without an ion emitter. The ionization was found to significantly enhance the filter efficiency in removing viable biological particles from the airflow. For example, when challenged with viable bacteria, the filter efficiency increased as much as four- to fivefold. For viable fungal spores, the ion-induced enhancement improved the efficiency by a factor of approximately 2. When testing with virus-carrying liquid droplets, the original removal efficiency provided by the filter was rather low: 9.09 +/- 4.84%. While the ion emission increased collection about fourfold, the efficiency did not reach 75-100% observed with bacteria and fungi. These findings, together with our previously published results for non-biological particles, demonstrate the feasibility of a new approach for reducing aerosol particles in HVAC systems used for indoor air quality control. Recirculated air in HVAC systems used for indoor air quality control in buildings often contains considerable number of viable bioaerosol particles because of limited efficiency of the filters installed in these systems. In the present study, we investigated - using aerosolized bacterial cells, bacterial and fungal spores, and virus-carrying particles - a novel idea of enhancing the performance of a low-efficiency HVAC filter utilizing continuous emission of unipolar ions in the filter vicinity. The findings described in this paper, together with our previously published results for non-biological particles, demonstrate the feasibility of the newly developed approach.

Canonical Statistical Model for Maximum Expected Immission of Wire Conductor in an Aperture Enclosure

NASA Technical Reports Server (NTRS)

Bremner, Paul G.; Vazquez, Gabriel; Christiano, Daniel J.; Trout, Dawn H.

2016-01-01

Prediction of the maximum expected electromagnetic pick-up of conductors inside a realistic shielding enclosure is an important canonical problem for system-level EMC design of space craft, launch vehicles, aircraft and automobiles. This paper introduces a simple statistical power balance model for prediction of the maximum expected current in a wire conductor inside an aperture enclosure. It calculates both the statistical mean and variance of the immission from the physical design parameters of the problem. Familiar probability density functions can then be used to predict the maximum expected immission for deign purposes. The statistical power balance model requires minimal EMC design information and solves orders of magnitude faster than existing numerical models, making it ultimately viable for scaled-up, full system-level modeling. Both experimental test results and full wave simulation results are used to validate the foundational model.

Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion.

PubMed

Gowrishankar, T R; Stewart, Donald A; Martin, Gregory T; Weaver, James C

2004-11-17

Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42 degrees C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45 degrees C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue.

Factorization and reduction methods for optimal control of distributed parameter systems

NASA Technical Reports Server (NTRS)

Burns, J. A.; Powers, R. K.

1985-01-01

A Chandrasekhar-type factorization method is applied to the linear-quadratic optimal control problem for distributed parameter systems. An aeroelastic control problem is used as a model example to demonstrate that if computationally efficient algorithms, such as those of Chandrasekhar-type, are combined with the special structure often available to a particular problem, then an abstract approximation theory developed for distributed parameter control theory becomes a viable method of solution. A numerical scheme based on averaging approximations is applied to hereditary control problems. Numerical examples are given.

Formulation and evaluation of Bacillus coagulans-loaded hypromellose mucoadhesive microspheres.

PubMed

Alli, Sk Md Athar

2011-01-01

Development of a novel delivery system has been attempted to deliver viable probiotic cells into the gut for a prolonged period of time while maintaining high numbers of viable cells within the formulation throughout the shelf-life of the product and during the gastrointestinal transit. Core mucoadhesive microspheres of Bacillus coagulans were developed employing several grades of hypromellose, a mucoadhesive polymer, following coacervation and phase separation technique and were subsequently enteric-coated with hypromellose phthalate. Microspheres were evaluated for percent yield; entrapment efficiency; in vitro swelling; surface morphology; particle size, size distribution, and zeta potential; flow property, mucoadhesion property by the ex vivo mucoadhesive strength test and the in vitro wash off test; in vitro release profile and release kinetic; in vivo probiotic activity; and stability. The values for the kinetic constant and regression coefficient of model-dependent approaches and the difference factor (f(1)), the similarity factor (f(2)), and the Rescigno index (ξ(1) and ξ(2)) of model independent approaches were determined for comparing in vitro dissolution profiles. Freeze dried B. coagulans cells were successfully formulated as enteric-coated mucoadhesive microspheres with satisfactory physical structure and yield. The viability of B. coagulans was maintained in the simulated gastric conditions and during processing; in simulated intestinal conditions exhibiting mucoadhesion, and controlling and extending the viable cell release following zero-order; and was satisfactorily stable at room temperature. Test results depict statistically significant effects of the hypromellose grade and their concentration on the performance and release profile of formulations.

Formulation and evaluation of Bacillus coagulans-loaded hypromellose mucoadhesive microspheres

PubMed Central

Alli, Sk Md Athar

2011-01-01

Development of a novel delivery system has been attempted to deliver viable probiotic cells into the gut for a prolonged period of time while maintaining high numbers of viable cells within the formulation throughout the shelf-life of the product and during the gastrointestinal transit. Core mucoadhesive microspheres of Bacillus coagulans were developed employing several grades of hypromellose, a mucoadhesive polymer, following coacervation and phase separation technique and were subsequently enteric-coated with hypromellose phthalate. Microspheres were evaluated for percent yield; entrapment efficiency; in vitro swelling; surface morphology; particle size, size distribution, and zeta potential; flow property, mucoadhesion property by the ex vivo mucoadhesive strength test and the in vitro wash off test; in vitro release profile and release kinetic; in vivo probiotic activity; and stability. The values for the kinetic constant and regression coefficient of model-dependent approaches and the difference factor (f1), the similarity factor (f2), and the Rescigno index (ξ1 and ξ2) of model independent approaches were determined for comparing in vitro dissolution profiles. Freeze dried B. coagulans cells were successfully formulated as enteric-coated mucoadhesive microspheres with satisfactory physical structure and yield. The viability of B. coagulans was maintained in the simulated gastric conditions and during processing; in simulated intestinal conditions exhibiting mucoadhesion, and controlling and extending the viable cell release following zero-order; and was satisfactorily stable at room temperature. Test results depict statistically significant effects of the hypromellose grade and their concentration on the performance and release profile of formulations. PMID:21674019

PolyMUMPs MEMS device to measure mechanical stiffness of single cells in aqueous media

NASA Astrophysics Data System (ADS)

Warnat, S.; King, H.; Forbrigger, C.; Hubbard, T.

2015-02-01

A method of experimentally determining the mechanical stiffness of single cells by using differential displacement measurements in a two stage spring system is presented. The spring system consists of a known MEMS reference spring and an unknown cellular stiffness: the ratio of displacements is related to the ratio of stiffness. A polyMUMPs implementation for aqueous media is presented and displacement measurements made from optical microphotographs using a FFT based displacement method with a repeatability of ~20 nm. The approach was first validated on a MEMS two stage spring system of known stiffness. The measured stiffness ratios of control structures (i) MEMS spring systems and (ii) polystyrene microspheres were found to agree with theoretical values. Mechanical tests were then performed on Saccharomyces cerevisiae (Baker’s yeast) in aqueous media. Cells were placed (using a micropipette) inside MEMS measuring structures and compressed between two jaws using an electrostatic actuator and displacements measured. Tested cells showed stiffness values between 5.4 and 8.4 N m-1 with an uncertainty of 11%. In addition, non-viable cells were tested by exposing viable cells to methanol. The resultant mean cell stiffness dropped by factor of 3 × and an explicit discrimination between viable and non-viable cells based on mechanical stiffness was seen.

Design of an air traffic computer simulation system to support investigation of civil tiltrotor aircraft operations

NASA Technical Reports Server (NTRS)

Rogers, Ralph V.

1992-01-01

This research project addresses the need to provide an efficient and safe mechanism to investigate the effects and requirements of the tiltrotor aircraft's commercial operations on air transportation infrastructures, particularly air traffic control. The mechanism of choice is computer simulation. Unfortunately, the fundamental paradigms of the current air traffic control simulation models do not directly support the broad range of operational options and environments necessary to study tiltrotor operations. Modification of current air traffic simulation models to meet these requirements does not appear viable given the range and complexity of issues needing resolution. As a result, the investigation of systemic, infrastructure issues surrounding the effects of tiltrotor commercial operations requires new approaches to simulation modeling. These models should be based on perspectives and ideas closer to those associated with tiltrotor air traffic operations.

Immobile Robots: AI in the New Millennium

NASA Technical Reports Server (NTRS)

Williams, Brian C.; Nayak, P. Pandurang

1996-01-01

A new generation of sensor rich, massively distributed, autonomous systems are being developed that have the potential for profound social, environmental, and economic change. These include networked building energy systems, autonomous space probes, chemical plant control systems, satellite constellations for remote ecosystem monitoring, power grids, biosphere-like life support systems, and reconfigurable traffic systems, to highlight but a few. To achieve high performance, these immobile robots (or immobots) will need to develop sophisticated regulatory and immune systems that accurately and robustly control their complex internal functions. To accomplish this, immobots will exploit a vast nervous system of sensors to model themselves and their environment on a grand scale. They will use these models to dramatically reconfigure themselves in order to survive decades of autonomous operations. Achieving these large scale modeling and configuration tasks will require a tight coupling between the higher level coordination function provided by symbolic reasoning, and the lower level autonomic processes of adaptive estimation and control. To be economically viable they will need to be programmable purely through high level compositional models. Self modeling and self configuration, coordinating autonomic functions through symbolic reasoning, and compositional, model-based programming are the three key elements of a model-based autonomous systems architecture that is taking us into the New Millennium.

Enumeration of Vibrio cholerae O1 in Bangladesh waters by fluorescent-antibody direct viable count.

PubMed Central

Brayton, P R; Tamplin, M L; Huq, A; Colwell, R R

1987-01-01

A field trial to enumerate Vibrio cholerae O1 in aquatic environments in Bangladesh was conducted, comparing fluorescent-antibody direct viable count with culture detection by the most-probable-number index. Specificity of a monoclonal antibody prepared against the O1 antigen was assessed and incorporated into the fluorescence staining method. All pond and water samples yielded higher counts of viable V. cholerae O1 by fluorescent-antibody direct viable count than by the most-probable-number index. Fluorescence microscopy is a more sensitive detection system than culture methods because it allows the enumeration of both culturable and nonculturable cells and therefore provides more precise monitoring of microbiological water quality. PMID:3324967

Assessment of Service Life for Regenerative ECLSS Resin Beds

NASA Technical Reports Server (NTRS)

Cloud, Dale L.; Keilich, Maria C.; Polis, Peter C.; Yanczura, Stephen J.

2013-01-01

The International Space Station (ISS) Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) manage and process water at various levels of cleanliness for multiple purposes. The effluent of theWPA and the influent of the OGA require water at very high levels of purity. The bulk of the water purification that occurs in both systems is performed by consumable activated carbon and ion exchange resin beds. Replacement beds must be available on orbit in order to continue the ISS critical processes of water purification and oxygen generation. Various hurdles exist in order to ensure viable spare resin beds. These include the characteristics of resin beds such as: storage environment, shelf life requirements, microbial growth, and variations in the levels and species of contaminants the beds are required to remove. Careful consideration has been given to match water models, bed capacities and spares traffic models to ensure that spares are always viable. The results of these studies and considerations, in particular, how shelf life requirements affect resin bed life management, are documented in this paper.

System Level Analysis of a Water PCM HX Integrated into Orion's Thermal Control System

NASA Technical Reports Server (NTRS)

Navarro, Moses; Hansen, Scott; Seth, Rubik; Ungar, Eugene

2015-01-01

In a cyclical heat load environment such as low Lunar orbit, a spacecraft's radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a "topper" to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development an Orion system level analysis was performed using Thermal Desktop for a water PCM HX integrated into Orion's thermal control system in a 100km Lunar orbit. The study verified of the thermal model by using a wax PCM and analyzed 1) placing the PCM on the Internal Thermal Control System (ITCS) versus the External Thermal Control System (ETCS) 2) use of 30/70 PGW verses 50/50 PGW and 3) increasing the radiator area in order to reduce PCM freeze times. The analysis showed that for the assumed operating and boundary conditions utilizing a water PCM HX on Orion is not a viable option for any case. Additionally, it was found that the radiator area would have to be increased by at least 40% in order to support a viable water-based PCM HX.

Separable Bilayer Microfiltration Device for Viable Label-free Enrichment of Circulating Tumour Cells

NASA Astrophysics Data System (ADS)

Zhou, Ming-Da; Hao, Sijie; Williams, Anthony J.; Harouaka, Ramdane A.; Schrand, Brett; Rawal, Siddarth; Ao, Zheng; Brennaman, Randall; Gilboa, Eli; Lu, Bo; Wang, Shuwen; Zhu, Jiyue; Datar, Ram; Cote, Richard; Tai, Yu-Chong; Zheng, Si-Yang

2014-12-01

The analysis of circulating tumour cells (CTCs) in cancer patients could provide important information for therapeutic management. Enrichment of viable CTCs could permit performance of functional analyses on CTCs to broaden understanding of metastatic disease. However, this has not been widely accomplished. Addressing this challenge, we present a separable bilayer (SB) microfilter for viable size-based CTC capture. Unlike other single-layer CTC microfilters, the precise gap between the two layers and the architecture of pore alignment result in drastic reduction in mechanical stress on CTCs, capturing them viably. Using multiple cancer cell lines spiked in healthy donor blood, the SB microfilter demonstrated high capture efficiency (78-83%), high retention of cell viability (71-74%), high tumour cell enrichment against leukocytes (1.7-2 × 103), and widespread ability to establish cultures post-capture (100% of cell lines tested). In a metastatic mouse model, SB microfilters successfully enriched viable mouse CTCs from 0.4-0.6 mL whole mouse blood samples and established in vitro cultures for further genetic and functional analysis. Our preliminary studies reflect the efficacy of the SB microfilter device to efficiently and reliably enrich viable CTCs in animal model studies, constituting an exciting technology for new insights in cancer research.

Infant fMRI: A Model System for Cognitive Neuroscience.

PubMed

Ellis, Cameron T; Turk-Browne, Nicholas B

2018-05-01

Our understanding of the typical human brain has benefitted greatly from studying different kinds of brains and their associated behavioral repertoires, including animal models and neuropsychological patients. This same comparative perspective can be applied to early development - the environment, behavior, and brains of infants provide a model system for understanding how the mature brain works. This approach requires noninvasive methods for measuring brain function in awake, behaving infants. fMRI is becoming increasingly viable for this purpose, with the unique ability to precisely measure the entire brain, including both cortical and subcortical structures. Here we discuss potential lessons from infant fMRI for several domains of adult cognition and consider the challenges of conducting such research and how they might be mitigated. Copyright © 2018 Elsevier Ltd. All rights reserved.

Health monitoring system for transmission shafts based on adaptive parameter identification

NASA Astrophysics Data System (ADS)

Souflas, I.; Pezouvanis, A.; Ebrahimi, K. M.

2018-05-01

A health monitoring system for a transmission shaft is proposed. The solution is based on the real-time identification of the physical characteristics of the transmission shaft i.e. stiffness and damping coefficients, by using a physical oriented model and linear recursive identification. The efficacy of the suggested condition monitoring system is demonstrated on a prototype transient engine testing facility equipped with a transmission shaft capable of varying its physical properties. Simulation studies reveal that coupling shaft faults can be detected and isolated using the proposed condition monitoring system. Besides, the performance of various recursive identification algorithms is addressed. The results of this work recommend that the health status of engine dynamometer shafts can be monitored using a simple lumped-parameter shaft model and a linear recursive identification algorithm which makes the concept practically viable.

The Importance of Detailed Component Simulations in the Feedsystem Development for a Two-Stage-to Orbit Reusable Launch Vehicle

NASA Technical Reports Server (NTRS)

Mazurkivich, Pete; Chandler, Frank; Grayson, Gary

2005-01-01

To meet the requirements for the 2nd Generation Reusable Launch Vehicle (RLV), a unique propulsion feed system concept was identified using crossfeed between the booster and orbiter stages that could reduce the Two-Stage-to-Orbit (TSTO) vehicle weight and development cost by approximately 25%. A Main Propulsion System (MPS) crossfeed water demonstration test program was configured to address all the activities required to reduce the risks for the MPS crossfeed system. A transient, one-dimensional system simulation was developed for the subscale crossfeed water flow tests. To ensure accurate representation of the crossfeed valve's dynamics in the system model, a high-fidelity, three-dimensional, computational fluid-dynamics (CFD) model was employed. The results from the CFD model were used to specify the valve's flow characteristics in the system simulation. This yielded a crossfeed system model that was anchored to the specific valve hardware and achieved good agreement with the measured test data. These results allowed the transient models to be correlated and validated and used for full scale mission predictions. The full scale model simulations indicate crossfeed is ' viable with the system pressure disturbances at the crossfeed transition being less than experienced by the propulsion system during engine start and shutdown transients.

Establishing Caenorhabditis elegans as a model for Mycobacterium avium subspecies hominissuis infection and intestinal colonization

PubMed Central

Everman, Jamie L.; Ziaie, Navid R.; Bechler, Jessica; Bermudez, Luiz E.

2015-01-01

ABSTRACT The nematode Caenorhabditis elegans has become a model system for studying the disease interaction between pathogens and the host. To determine whether the transparent nematode could serve as a useful model for Mycobacterium avium subspecies hominissuis (MAH) infection of the intestinal tract, worms were fed MAH and assayed for the effects of the bacterial infection on the worm. It was observed during feeding that viable MAH increases in the intestinal lumen in a time dependent manner. Ingestion of MAH was deemed non-toxic to worms as MAH-fed populations have similar survival curves to those fed E. coli strain OP50. Pulse-chase analysis using E. coli strain OP50 revealed that MAH colonize the intestinal tract, as viable MAH remain within the intestine after the assay. Visualization of intestinal MAH using histology and transmission electron microscopy demonstrates that MAH localizes to the intestinal lumen, as well as establishes direct contact with intestinal epithelium. Bacterial colonization appears to have a detrimental effect on the microvilli of the intestinal epithelial cells. The MAH ΔGPL/4B2 strain with a mutation in glycopeptidolipid production is deficient in binding to human epithelial cells (HEp-2), as well as deficient in its ability to bind to and colonize the intestinal tract of C. elegans as efficiently as wild-type MAH. These data indicate the C. elegans may serve as a useful model system for MAH pathogenesis and in determining the mechanisms used by MAH during infection and colonization of the intestinal epithelium. PMID:26405050

Modeling the yield potential of dryland canola under current and future climates in California

NASA Astrophysics Data System (ADS)

George, N.; Kaffka, S.; Beeck, C.; Bucaram, S.; Zhang, J.

2012-12-01

Models predict that the climate of California will become hotter, drier and more variable under future climate change scenarios. This will lead to both increased irrigation demand and reduced irrigation water availability. In addition, it is predicted that most common Californian crops will suffer a concomitant decline in productivity. To remain productive and economically viable, future agricultural systems will need to have greater water use efficiency, tolerance of high temperatures, and tolerance of more erratic temperature and rainfall patterns. Canola (Brassica napus) is the third most important oilseed globally, supporting large and well-established agricultural industries in Canada, Europe and Australia. It is an agronomically useful and economically valuable crop, with multiple end markets, that can be grown in California as a dryland winter rotation with little to no irrigation demand. This gives canola great potential as a new crop for Californian farmers both now and as the climate changes. Given practical and financial limitations it is not always possible to immediately or widely evaluate a crop in a new region. Crop production models are therefore valuable tools for assessing the potential of new crops, better targeting further field research, and refining research questions. APSIM is a modular modeling framework developed by the Agricultural Production Systems Research Unit in Australia, it combines biophysical and management modules to simulate cropping systems. This study was undertaken to examine the yield potential of Australian canola varieties having different water requirements and maturity classes in California using APSIM. The objective of the work was to identify the agricultural regions of California most ideally suited to the production of Australian cultivars of canola and to simulate the production of canola in these regions to estimate yield-potential. This will establish whether the introduction and in-field evaluation of better-adapted canola varieties can be justified, and the potential value of a California canola industry both now and in the future. Winter annual crops like canola use rainfall in a Mediterranean climate like California more efficiently than spring or summer crops. Our results suggest that under current production costs and seed prices, dry farmed canola will have good potential in certain areas of the California. Canola yields decline with annual winter precipitation, however economically viable yields are still achieved at relatively precipitation levels (200 mm). Results from simulation, combined with related economic modeling (reported elsewhere) suggest that canola will be viable in a variety of production systems in the northern Sacramento Valley and some coastal locations, even under drier future climate scenarios. The in-field evaluation of Australian canola varieties should contribute to maintain or improving resource use efficiency and farm profitability.

Rapid and automated enumeration of viable bacteria in compost using a micro-colony auto counting system.

PubMed

Wang, Xiaodan; Yamaguchi, Nobuyasu; Someya, Takashi; Nasu, Masao

2007-10-01

The micro-colony method was used to enumerate viable bacteria in composts. Cells were vacuum-filtered onto polycarbonate filters and incubated for 18 h on LB medium at 37 degrees C. Bacteria on the filters were stained with SYBR Green II, and enumerated using a newly developed micro-colony auto counting system which can automatically count micro-colonies on half the area of the filter within 90 s. A large number of bacteria in samples retained physiological activity and formed micro-colonies within 18 h, whereas most could not form large colonies on conventional media within 1 week. The results showed that this convenient technique can enumerate viable bacteria in compost rapidly for its efficient quality control.

Enabling Requirements-Based Programming for Highly-Dependable Complex Parallel and Distributed Systems

NASA Technical Reports Server (NTRS)

Hinchey, Michael G.; Rash, James L.; Rouff, Christopher A.

2005-01-01

The manual application of formal methods in system specification has produced successes, but in the end, despite any claims and assertions by practitioners, there is no provable relationship between a manually derived system specification or formal model and the customer's original requirements. Complex parallel and distributed system present the worst case implications for today s dearth of viable approaches for achieving system dependability. No avenue other than formal methods constitutes a serious contender for resolving the problem, and so recognition of requirements-based programming has come at a critical juncture. We describe a new, NASA-developed automated requirement-based programming method that can be applied to certain classes of systems, including complex parallel and distributed systems, to achieve a high degree of dependability.

Quantitative modeling of viable cell density, cell size, intracellular conductivity, and membrane capacitance in batch and fed-batch CHO processes using dielectric spectroscopy.

PubMed

Opel, Cary F; Li, Jincai; Amanullah, Ashraf

2010-01-01

Dielectric spectroscopy was used to analyze typical batch and fed-batch CHO cell culture processes. Three methods of analysis (linear modeling, Cole-Cole modeling, and partial least squares regression), were used to correlate the spectroscopic data with routine biomass measurements [viable packed cell volume, viable cell concentration (VCC), cell size, and oxygen uptake rate (OUR)]. All three models predicted offline biomass measurements accurately during the growth phase of the cultures. However, during the stationary and decline phases of the cultures, the models decreased in accuracy to varying degrees. Offline cell radius measurements were unsuccessfully used to correct for the deviations from the linear model, indicating that physiological changes affecting permittivity were occurring. The beta-dispersion was analyzed using the Cole-Cole distribution parameters Deltaepsilon (magnitude of the permittivity drop), f(c) (critical frequency), and alpha (Cole-Cole parameter). Furthermore, the dielectric parameters static internal conductivity (sigma(i)) and membrane capacitance per area (C(m)) were calculated for the cultures. Finally, the relationship between permittivity, OUR, and VCC was examined, demonstrating how the definition of viability is critical when analyzing biomass online. The results indicate that the common assumptions of constant size and dielectric properties used in dielectric analysis are not always valid during later phases of cell culture processes. The findings also demonstrate that dielectric spectroscopy, while not a substitute for VCC, is a complementary measurement of viable biomass, providing useful auxiliary information about the physiological state of a culture. (c) 2010 American Institute of Chemical Engineers

The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life

PubMed Central

Koonin, Eugene V

2007-01-01

Background Recent developments in cosmology radically change the conception of the universe as well as the very notions of "probable" and "possible". The model of eternal inflation implies that all macroscopic histories permitted by laws of physics are repeated an infinite number of times in the infinite multiverse. In contrast to the traditional cosmological models of a single, finite universe, this worldview provides for the origin of an infinite number of complex systems by chance, even as the probability of complexity emerging in any given region of the multiverse is extremely low. This change in perspective has profound implications for the history of any phenomenon, and life on earth cannot be an exception. Hypothesis Origin of life is a chicken and egg problem: for biological evolution that is governed, primarily, by natural selection, to take off, efficient systems for replication and translation are required, but even barebones cores of these systems appear to be products of extensive selection. The currently favored (partial) solution is an RNA world without proteins in which replication is catalyzed by ribozymes and which serves as the cradle for the translation system. However, the RNA world faces its own hard problems as ribozyme-catalyzed RNA replication remains a hypothesis and the selective pressures behind the origin of translation remain mysterious. Eternal inflation offers a viable alternative that is untenable in a finite universe, i.e., that a coupled system of translation and replication emerged by chance, and became the breakthrough stage from which biological evolution, centered around Darwinian selection, took off. A corollary of this hypothesis is that an RNA world, as a diverse population of replicating RNA molecules, might have never existed. In this model, the stage for Darwinian selection is set by anthropic selection of complex systems that rarely but inevitably emerge by chance in the infinite universe (multiverse). Conclusion The plausibility of different models for the origin of life on earth directly depends on the adopted cosmological scenario. In an infinite universe (multiverse), emergence of highly complex systems by chance is inevitable. Therefore, under this cosmology, an entity as complex as a coupled translation-replication system should be considered a viable breakthrough stage for the onset of biological evolution. Reviewers This article was reviewed by Eric Bapteste, David Krakauer, Sergei Maslov, and Itai Yanai. PMID:17540027

The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life.

PubMed

Koonin, Eugene V

2007-05-31

Recent developments in cosmology radically change the conception of the universe as well as the very notions of "probable" and "possible". The model of eternal inflation implies that all macroscopic histories permitted by laws of physics are repeated an infinite number of times in the infinite multiverse. In contrast to the traditional cosmological models of a single, finite universe, this worldview provides for the origin of an infinite number of complex systems by chance, even as the probability of complexity emerging in any given region of the multiverse is extremely low. This change in perspective has profound implications for the history of any phenomenon, and life on earth cannot be an exception. Origin of life is a chicken and egg problem: for biological evolution that is governed, primarily, by natural selection, to take off, efficient systems for replication and translation are required, but even barebones cores of these systems appear to be products of extensive selection. The currently favored (partial) solution is an RNA world without proteins in which replication is catalyzed by ribozymes and which serves as the cradle for the translation system. However, the RNA world faces its own hard problems as ribozyme-catalyzed RNA replication remains a hypothesis and the selective pressures behind the origin of translation remain mysterious. Eternal inflation offers a viable alternative that is untenable in a finite universe, i.e., that a coupled system of translation and replication emerged by chance, and became the breakthrough stage from which biological evolution, centered around Darwinian selection, took off. A corollary of this hypothesis is that an RNA world, as a diverse population of replicating RNA molecules, might have never existed. In this model, the stage for Darwinian selection is set by anthropic selection of complex systems that rarely but inevitably emerge by chance in the infinite universe (multiverse). The plausibility of different models for the origin of life on earth directly depends on the adopted cosmological scenario. In an infinite universe (multiverse), emergence of highly complex systems by chance is inevitable. Therefore, under this cosmology, an entity as complex as a coupled translation-replication system should be considered a viable breakthrough stage for the onset of biological evolution. This article was reviewed by Eric Bapteste, David Krakauer, Sergei Maslov, and Itai Yanai.

Information transfer satellite concept study. Volume 2: Technical

NASA Technical Reports Server (NTRS)

Bergin, P.; Kincade, C.; Kurpiewski, D.; Leinhaupel, F.; Millican, F.; Onstad, R.

1971-01-01

The ITS concept study is preceded by two requirements studies whose primary objectives are to identify viable demands and to develop the functional requirements associated with these demands. In addition to continuing this basic activity the ITS concept study objectives are to: (1) develop tools and techniques for planning advanced information transfer satellite communications systems, and to (2) select viable systems for further analysis both in their near-term and in the far-term aspects.

Creating an environment for caring using lean principles of the Virginia Mason Production System.

PubMed

Nelson-Peterson, Dana L; Leppa, Carol J

2007-06-01

As healthcare leaders search for viable options to cut costs, increase efficiencies, and improve the product that they offer to customers, many are looking at different business models to adopt. At the same time, an aging workforce of nurses feel the pressure of being overworked and understaffed, resulting in both decreased job and patient satisfaction. Virginia Mason Medical Center in Seattle, Wash, has implemented the Virginia Mason Production System, using proven concepts adapted from the Toyota Production System that effectively eliminate "muda" or waste, in workplace processes. The authors discuss the application of the Virginia Mason Production System and how it has resulted in increased time for nurses to care for their patients.

Analysis of variation in oil pressure in lubricating system

NASA Astrophysics Data System (ADS)

Sharma, Sumit; Upreti, Mritunjay; Sharma, Bharat; Poddar, Keshav

2018-05-01

Automotive Maintenance for an engine contributes to its reliability, energy efficiency and repair cost reduction. Modeling of engine performance and fault detection require large amount of data, which are usually obtained on test benches. This report presents a methodical study on analysis of variation in lubrication system of various medium speed engines. Further this study is limited to the influence of Engine Oil Pressure on frictional losses, Torque analysis for various Oil Pressures and an analytical analysis of engine Lubrication System. The data collected from various Engines under diagnostics is represented graphically. Finally the illustrated results were used as a viable source for detection and troubleshooting of faults in Lubrication System of regular passenger vehicle.

Spitzer Observations of OGLE-2015-BLG-1212 Reveal a New Path toward Breaking Strong Microlens Degeneracies

NASA Technical Reports Server (NTRS)

Bozza, V.; Shvartzvald, Y.; Udalski, A.; Novati, S.Calchi; Bond, I. A.; Han, C.; Hundertmark, M.; Poleski, R.; Pawlak, M.; Szymanski, M. K.;

The Scenario-Based Engineering Process (SEP): a user-centered approach for the development of health care systems.

PubMed

Harbison, K; Kelly, J; Burnell, L; Silva, J

1995-01-01

The Scenario-based Engineering Process (SEP) is a user-focused methodology for large and complex system design. This process supports new application development from requirements analysis with domain models to component selection, design and modification, implementation, integration, and archival placement. It is built upon object-oriented methodologies, domain modeling strategies, and scenario-based techniques to provide an analysis process for mapping application requirements to available components. We are using SEP in the health care applications that we are developing. The process has already achieved success in the manufacturing and military domains and is being adopted by many organizations. SEP should prove viable in any domain containing scenarios that can be decomposed into tasks.

Efficient Agent-Based Models for Non-Genomic Evolution

NASA Technical Reports Server (NTRS)

Gupta, Nachi; Agogino, Adrian; Tumer, Kagan

2006-01-01

Modeling dynamical systems composed of aggregations of primitive proteins is critical to the field of astrobiological science involving early evolutionary structures and the origins of life. Unfortunately traditional non-multi-agent methods either require oversimplified models or are slow to converge to adequate solutions. This paper shows how to address these deficiencies by modeling the protein aggregations through a utility based multi-agent system. In this method each agent controls the properties of a set of proteins assigned to that agent. Some of these properties determine the dynamics of the system, such as the ability for some proteins to join or split other proteins, while additional properties determine the aggregation s fitness as a viable primitive cell. We show that over a wide range of starting conditions, there are mechanisins that allow protein aggregations to achieve high values of overall fitness. In addition through the use of agent-specific utilities that remain aligned with the overall global utility, we are able to reach these conclusions with 50 times fewer learning steps.

Statistical distribution of mechanical properties for three graphite-epoxy material systems

NASA Technical Reports Server (NTRS)

Reese, C.; Sorem, J., Jr.

1981-01-01

Graphite-epoxy composites are playing an increasing role as viable alternative materials in structural applications necessitating thorough investigation into the predictability and reproducibility of their material strength properties. This investigation was concerned with tension, compression, and short beam shear coupon testing of large samples from three different material suppliers to determine their statistical strength behavior. Statistical results indicate that a two Parameter Weibull distribution model provides better overall characterization of material behavior for the graphite-epoxy systems tested than does the standard Normal distribution model that is employed for most design work. While either a Weibull or Normal distribution model provides adequate predictions for average strength values, the Weibull model provides better characterization in the lower tail region where the predictions are of maximum design interest. The two sets of the same material were found to have essentially the same material properties, and indicate that repeatability can be achieved.

Development of a telemedicine model for emerging countries: a case study on pediatric oncology in Brazil.

PubMed

Hira, A Y; Nebel de Mello, A; Faria, R A; Odone Filho, V; Lopes, R D; Zuffo, M K

2006-01-01

This article discusses a telemedicine model for emerging countries, through the description of ONCONET, a telemedicine initiative applied to pediatric oncology in Brazil. The ONCONET core technology is a Web-based system that offers health information and other services specialized in childhood cancer such as electronic medical records and cooperative protocols for complex treatments. All Web-based services are supported by the use of high performance computing infrastructure based on clusters of commodity computers. The system was fully implemented on an open-source and free-software approach. Aspects of modeling, implementation and integration are covered. A model, both technologically and economically viable, was created through the research and development of in-house solutions adapted to the emerging countries reality and with focus on scalability both in the total number of patients and in the national infrastructure.

Giving students the run of sprinting models

NASA Astrophysics Data System (ADS)

Heck, André; Ellermeijer, Ton

2009-11-01

A biomechanical study of sprinting is an interesting task for students who have a background in mechanics and calculus. These students can work with real data and do practical investigations similar to the way sports scientists do research. Student research activities are viable when the students are familiar with tools to collect and work with data from sensors and video recordings and with modeling tools for comparing simulation and experimental results. This article describes a multipurpose system, named COACH, that offers a versatile integrated set of tools for learning, doing, and teaching mathematics and science in a computer-based inquiry approach. Automated tracking of reference points and correction of perspective distortion in videos, state-of-the-art algorithms for data smoothing and numerical differentiation, and graphical system dynamics based modeling are some of the built-in techniques that are suitable for motion analysis. Their implementation and their application in student activities involving models of running are discussed.

Cannabidiol Reduces Leukemic Cell Size - But Is It Important?

PubMed

Kalenderoglou, Nikoletta; Macpherson, Tara; Wright, Karen L

2017-01-01

The anti-cancer effect of the plant-derived cannabinoid, cannabidiol, has been widely demonstrated both in vivo and in vitro . However, this body of preclinical work has not been translated into clinical use. Key issues around this failure can be related to narrow dose effects, the cell model used and incomplete efficacy. A model of acute lymphoblastic disease, the Jurkat T cell line, has been used extensively to study the cannabinoid system in the immune system and cannabinoid-induced apoptosis. Using these cells, this study sought to investigate the outcome of those remaining viable cells post-treatment with cannabidiol, both in terms of cell size and tracking any subsequent recovery. The phosphorylation status of the mammalian Target of Rapamycin (mTOR) signaling pathway and the downstream target ribosomal protein S6, were measured. The ability of cannabidiol to exert its effect on cell viability was also evaluated in physiological oxygen conditions. Cannabidiol reduced cell viability incompletely, and slowed the cell cycle with fewer cells in the G2/M phase of the cell cycle. Cannabidiol reduced phosphorylation of mTOR, PKB and S6 pathways related to survival and cell size. The remaining population of viable cells that were cultured in nutrient rich conditions post-treatment were able to proliferate, but did not recover to control cell numbers. However, the proportion of viable cells that were gated as small, increased in response to cannabidiol and normally sized cells decreased. This proportion of small cells persisted in the recovery period and did not return to basal levels. Finally, cells grown in 12% oxygen (physiological normoxia) were more resistant to cannabidiol. In conclusion, these results indicate that cannabidiol causes a reduction in cell size, which persists post-treatment. However, resistance to cannabidiol under physiological normoxia for these cells would imply that cannabidiol may not be useful in the clinic as an anti-leukemic agent.

Cannabidiol Reduces Leukemic Cell Size – But Is It Important?

PubMed Central

Kalenderoglou, Nikoletta; Macpherson, Tara; Wright, Karen L.

2017-01-01

The anti-cancer effect of the plant-derived cannabinoid, cannabidiol, has been widely demonstrated both in vivo and in vitro. However, this body of preclinical work has not been translated into clinical use. Key issues around this failure can be related to narrow dose effects, the cell model used and incomplete efficacy. A model of acute lymphoblastic disease, the Jurkat T cell line, has been used extensively to study the cannabinoid system in the immune system and cannabinoid-induced apoptosis. Using these cells, this study sought to investigate the outcome of those remaining viable cells post-treatment with cannabidiol, both in terms of cell size and tracking any subsequent recovery. The phosphorylation status of the mammalian Target of Rapamycin (mTOR) signaling pathway and the downstream target ribosomal protein S6, were measured. The ability of cannabidiol to exert its effect on cell viability was also evaluated in physiological oxygen conditions. Cannabidiol reduced cell viability incompletely, and slowed the cell cycle with fewer cells in the G2/M phase of the cell cycle. Cannabidiol reduced phosphorylation of mTOR, PKB and S6 pathways related to survival and cell size. The remaining population of viable cells that were cultured in nutrient rich conditions post-treatment were able to proliferate, but did not recover to control cell numbers. However, the proportion of viable cells that were gated as small, increased in response to cannabidiol and normally sized cells decreased. This proportion of small cells persisted in the recovery period and did not return to basal levels. Finally, cells grown in 12% oxygen (physiological normoxia) were more resistant to cannabidiol. In conclusion, these results indicate that cannabidiol causes a reduction in cell size, which persists post-treatment. However, resistance to cannabidiol under physiological normoxia for these cells would imply that cannabidiol may not be useful in the clinic as an anti-leukemic agent. PMID:28392768

Hardware and software reliability estimation using simulations

NASA Technical Reports Server (NTRS)

Swern, Frederic L.

1994-01-01

The simulation technique is used to explore the validation of both hardware and software. It was concluded that simulation is a viable means for validating both hardware and software and associating a reliability number with each. This is useful in determining the overall probability of system failure of an embedded processor unit, and improving both the code and the hardware where necessary to meet reliability requirements. The methodologies were proved using some simple programs, and simple hardware models.

Augmented reality for anatomical education.

PubMed

Thomas, Rhys Gethin; John, Nigel William; Delieu, John Michael

2010-03-01

The use of Virtual Environments has been widely reported as a method of teaching anatomy. Generally such environments only convey the shape of the anatomy to the student. We present the Bangor Augmented Reality Education Tool for Anatomy (BARETA), a system that combines Augmented Reality (AR) technology with models produced using Rapid Prototyping (RP) technology, to provide the student with stimulation for touch as well as sight. The principal aims of this work were to provide an interface more intuitive than a mouse and keyboard, and to evaluate such a system as a viable supplement to traditional cadaver based education.

Flight test results for a separate surface stability augmented Beech model 99

NASA Technical Reports Server (NTRS)

Jenks, G. E.; Henry, H. F.; Roskam, J.

1977-01-01

A flight evaluation of a Beech model 99 equipped with an attitude command control system incorporating separate surface stability augmentation (SSSA) was conducted to determine whether an attitude command control system could be implemented using separate surface controls, and to determine whether the handling and ride qualities of the aircraft were improved by the SSSA attitude command system. The results of the program revealed that SSSA is a viable approach to implementing attitude command and also that SSSA has the capability of performing less demanding augmentation tasks such as yaw damping, wing leveling, and pitch damping. The program also revealed that attitude command did improve the pilot rating and ride qualities of the airplane while flying an IFR mission in turbulence. Some disadvantages of the system included the necessity of holding aileron force in a banked turn and excessive stiffness in the pitch axis.

Tumor-volume simulation during radiotherapy for head-and-neck cancer using a four-level cell population model.

PubMed

Chvetsov, Alexei V; Dong, Lei; Palta, Jantinder R; Amdur, Robert J

2009-10-01

To develop a fast computational radiobiologic model for quantitative analysis of tumor volume during fractionated radiotherapy. The tumor-volume model can be useful for optimizing image-guidance protocols and four-dimensional treatment simulations in proton therapy that is highly sensitive to physiologic changes. The analysis is performed using two approximations: (1) tumor volume is a linear function of total cell number and (2) tumor-cell population is separated into four subpopulations: oxygenated viable cells, oxygenated lethally damaged cells, hypoxic viable cells, and hypoxic lethally damaged cells. An exponential decay model is used for disintegration and removal of oxygenated lethally damaged cells from the tumor. We tested our model on daily volumetric imaging data available for 14 head-and-neck cancer patients treated with an integrated computed tomography/linear accelerator system. A simulation based on the averaged values of radiobiologic parameters was able to describe eight cases during the entire treatment and four cases partially (50% of treatment time) with a maximum 20% error. The largest discrepancies between the model and clinical data were obtained for small tumors, which may be explained by larger errors in the manual tumor volume delineation procedure. Our results indicate that the change in gross tumor volume for head-and-neck cancer can be adequately described by a relatively simple radiobiologic model. In future research, we propose to study the variation of model parameters by fitting to clinical data for a cohort of patients with head-and-neck cancer and other tumors. The potential impact of other processes, like concurrent chemotherapy, on tumor volume should be evaluated.

Challenge of N95 Filtering Facepiece Respirators with Viable H1N1 Influenza Aerosols

PubMed Central

Harnish, Delbert A.; Heimbuch, Brian K.; Husband, Michael; Lumley, April E.; Kinney, Kimberly; Shaffer, Ronald E.; Wander, Joseph D.

2015-01-01

OBJECTIVE Specification of appropriate personal protective equipment for respiratory protection against influenza is somewhat controversial. In a clinical environment, N95 filtering facepiece respirators (FFRs) are often recommended for respiratory protection against infectious aerosols. This study evaluates the ability of N95 FFRs to capture viable H1N1 influenza aerosols. METHODS Five N95 FFR models were challenged with aerosolized viable H1N1 influenza and inert polystyrene latex particles at continuous flow rates of 85 and 170 liters per minute. Virus was assayed using Madin-Darby canine kidney cells to determine the median tissue culture infective dose (TCID50). Aerosols were generated using a Collison nebulizer containing H1N1 influenza virus at 1 × 108 TCID50/mL. To determine filtration efficiency, viable sampling was performed upstream and downstream of the FFR. RESULTS N95 FFRs filtered 0.8-µm particles of both H1N1 influenza and inert origins with more than 95% efficiency. With the exception of 1 model, no statistically significant difference in filtration performance was observed between influenza and inert particles of similar size. Although statistically significant differences were observed for 2 models when comparing the 2 flow rates, the differences have no significance to protection. CONCLUSIONS This study empirically demonstrates that a National Institute for Occupational Safety and Health–approved N95 FFR captures viable H1N1 influenza aerosols as well as or better than its N95 rating, suggesting that a properly fitted FFR reduces inhalation exposure to airborne influenza virus. This study also provides evidence that filtration efficiency is based primarily on particle size rather than the nature of the particle’s origin. PMID:23571366

Water-management models in Florida from ERTS-1 data. [Everglades National Park

NASA Technical Reports Server (NTRS)

Higer, A. L.; Coker, A. E.; Cordes, E. H.

1974-01-01

A prototype multiparameter data acquisition network, installed and operated by the U.S. Geological Survey is a viable approach for obtaining near real-time data needed to solve hydrologic problems confronting nearly 2.5 million residents of south Florida. Selected water quantity and quality data obtained from ground stations are transmitted for relay via ERTS-1 to NASA receiving stations in virtual real time. This data relay system has been very reliable and, by coupling the ground information with ERTS imagery, a modeling technique is available for water resource management in south Florida. An ecological model has been designed for the Shark River Slough in Everglades National Park.

2-D Fused Image Reconstruction approach for Microwave Tomography: a theoretical assessment using FDTD Model.

PubMed

Bindu, G; Semenov, S

2013-01-01

This paper describes an efficient two-dimensional fused image reconstruction approach for Microwave Tomography (MWT). Finite Difference Time Domain (FDTD) models were created for a viable MWT experimental system having the transceivers modelled using thin wire approximation with resistive voltage sources. Born Iterative and Distorted Born Iterative methods have been employed for image reconstruction with the extremity imaging being done using a differential imaging technique. The forward solver in the imaging algorithm employs the FDTD method of solving the time domain Maxwell's equations with the regularisation parameter computed using a stochastic approach. The algorithm is tested with 10% noise inclusion and successful image reconstruction has been shown implying its robustness.

Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

PubMed Central

Gowrishankar, TR; Stewart, Donald A; Martin, Gregory T; Weaver, James C

2004-01-01

Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue. PMID:15548324

“Humanized mice for HIV and AIDS research”

PubMed Central

Garcia, J. Victor

2016-01-01

HIV has a very limited species tropism that prevents the use of most conventional small animal models for AIDS research. The in vivo analysis of HIV/AIDS has benefited extensively from novel chimeric animal models that accurately recapitulate key aspects of the human condition. Specifically, immunodeficient mice that are systemically repopulated with human hematolymphoid cells offer a viable alternative for the study of a multitude of highly relevant aspects of HIV replication, pathogenesis, therapy, transmission, prevention, and eradication. This article summarizes some of the multiple contributions that humanized mouse models of HIV infection have made to the field of AIDS research. These models have proven to be highly informative and hold great potential for accelerating multiple aspects of HIV research in the future. PMID:27447446

Modelling biofilm-induced formation damage and biocide treatment in subsurface geosystems

PubMed Central

Ezeuko, C C; Sen, A; Gates, I D

2013-01-01

Biofilm growth in subsurface porous media, and its treatment with biocides (antimicrobial agents), involves a complex interaction of biogeochemical processes which provide non-trivial mathematical modelling challenges. Although there are literature reports of mathematical models to evaluate biofilm tolerance to biocides, none of these models have investigated biocide treatment of biofilms growing in interconnected porous media with flow. In this paper, we present a numerical investigation using a pore network model of biofilm growth, formation damage and biocide treatment. The model includes three phases (aqueous, adsorbed biofilm, and solid matrix), a single growth-limiting nutrient and a single biocide dissolved in the water. Biofilm is assumed to contain a single species of microbe, in which each cell can be a viable persister, a viable non-persister, or non-viable (dead). Persisters describe small subpopulation of cells which are tolerant to biocide treatment. Biofilm tolerance to biocide treatment is regulated by persister cells and includes ‘innate’ and ‘biocide-induced’ factors. Simulations demonstrate that biofilm tolerance to biocides can increase with biofilm maturity, and that biocide treatment alone does not reverse biofilm-induced formation damage. Also, a successful application of biological permeability conformance treatment involving geologic layers with flow communication is more complicated than simply engineering the attachment of biofilm-forming cells at desired sites. PMID:23164434

Extrapolation of systemic bioavailability assessing skin absorption and epidermal and hepatic metabolism of aromatic amine hair dyes in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manwaring, John, E-mail: manwaring.jd@pg.com; Rothe, Helga; Obringer, Cindy

Approaches to assess the role of absorption, metabolism and excretion of cosmetic ingredients that are based on the integration of different in vitro data are important for their safety assessment, specifically as it offers an opportunity to refine that safety assessment. In order to estimate systemic exposure (AUC) to aromatic amine hair dyes following typical product application conditions, skin penetration and epidermal and systemic metabolic conversion of the parent compound was assessed in human skin explants and human keratinocyte (HaCaT) and hepatocyte cultures. To estimate the amount of the aromatic amine that can reach the general circulation unchanged after passagemore » through the skin the following toxicokinetically relevant parameters were applied: a) Michaelis–Menten kinetics to quantify the epidermal metabolism; b) the estimated keratinocyte cell abundance in the viable epidermis; c) the skin penetration rate; d) the calculated Mean Residence Time in the viable epidermis; e) the viable epidermis thickness and f) the skin permeability coefficient. In a next step, in vitro hepatocyte K{sub m} and V{sub max} values and whole liver mass and cell abundance were used to calculate the scaled intrinsic clearance, which was combined with liver blood flow and fraction of compound unbound in the blood to give hepatic clearance. The systemic exposure in the general circulation (AUC) was extrapolated using internal dose and hepatic clearance, and C{sub max} was extrapolated (conservative overestimation) using internal dose and volume of distribution, indicating that appropriate toxicokinetic information can be generated based solely on in vitro data. For the hair dye, p-phenylenediamine, these data were found to be in the same order of magnitude as those published for human volunteers. - Highlights: • An entirely in silico/in vitro approach to predict in vivo exposure to dermally applied hair dyes • Skin penetration and epidermal conversion assessed in human skin explants and HaCaT • Systemic metabolism was modeled using hepatocyte cultures. • Toxicokinetically relevant parameters were applied to estimate systemic exposure. • There was a good agreement between in vitro and in vivo data.« less

Systems metabolic engineering: genome-scale models and beyond.

PubMed

Blazeck, John; Alper, Hal

2010-07-01

The advent of high throughput genome-scale bioinformatics has led to an exponential increase in available cellular system data. Systems metabolic engineering attempts to use data-driven approaches--based on the data collected with high throughput technologies--to identify gene targets and optimize phenotypical properties on a systems level. Current systems metabolic engineering tools are limited for predicting and defining complex phenotypes such as chemical tolerances and other global, multigenic traits. The most pragmatic systems-based tool for metabolic engineering to arise is the in silico genome-scale metabolic reconstruction. This tool has seen wide adoption for modeling cell growth and predicting beneficial gene knockouts, and we examine here how this approach can be expanded for novel organisms. This review will highlight advances of the systems metabolic engineering approach with a focus on de novo development and use of genome-scale metabolic reconstructions for metabolic engineering applications. We will then discuss the challenges and prospects for this emerging field to enable model-based metabolic engineering. Specifically, we argue that current state-of-the-art systems metabolic engineering techniques represent a viable first step for improving product yield that still must be followed by combinatorial techniques or random strain mutagenesis to achieve optimal cellular systems.

Power Systems of the Future: A 21st Century Power Partnership Thought Leadership Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinaman, Owen; Miller, Mackay; Adil, Ali

This report summarizes key forces driving transformation in the power sector around the world, presents a framework for evaluating decisions regarding extent and pace of change, and defines pathways for transformation. Powerful trends in technology, policy environments, financing, and business models are driving change in power sectors globally. In light of these trends, the question is no longer whether power systems will be transformed, but rather how these transformations will occur. Three approaches to policy and technology decision-making can guide these transformations: adaptive, reconstructive, and evolutionary. Within these approaches, we explore the five pathways that have emerged as viable modelsmore » for power system transformation.« less

Spreading of infectious materials from the laser interaction zone: viruses and bacteria

NASA Astrophysics Data System (ADS)

Weber, Lothar W.

1996-12-01

Actual occupational infections of medical staff is dominated by HBV, HIV and HCV-infections by dermal blood inoculation like needle injuries. What amount of these blood borne infections was possibly done via the aerosol pathway is unknown today. Looking at the laser generated aerodynamic particle sizes and the particle size of human pathogen viruses as circulating or cell fixed units shows common transmission abilities to the human respiratory system. In cell tissue monolayer model systems and contaminated serum systems with virus infections this mechanics were demonstrated as viable. For safety evaluation, the lifetime, spreading behavior and infection potential by viruses and bacterias of contaminated human laser aerosol must be further characterized.

Development of a Twin-spool Turbofan Engine Simulation Using the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)

NASA Technical Reports Server (NTRS)

Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Johathan S.

2014-01-01

The Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3 of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.

Breeding objectives for indigenous chicken: model development and application to different production systems.

PubMed

Okeno, Tobias O; Magothe, Thomas M; Kahi, Alexander K; Peters, Kurt J

2013-01-01

A bio-economic model was developed to evaluate the utilisation of indigenous chickens (IC) under different production systems accounting for the risk attitude of the farmers. The model classified the production systems into three categories based on the level of management: free-range system (FRS), where chickens were left to scavenge for feed resources with no supplementation and healthcare; intensive system (IS), where the chickens were permanently confined and supplied with rationed feed and healthcare; and semi-intensive system (SIS), a hybrid of FRS and IS, where the chickens were partially confined, supplemented with rationed feeds, provided with healthcare and allowed to scavenge within the homestead or in runs. The model allows prediction of the live weights and feed intake at different stages in the life cycle of the IC and can compute the profitability of each production system using both traditional and risk-rated profit models. The input parameters used in the model represent a typical IC production system in developing countries but are flexible and therefore can be modified to suit specific situations and simulate profitability and costs of other poultry species production systems. The model has the capability to derive the economic values as changes in the genetic merit of the biological parameter results in marginal changes in profitability and costs of the production systems. The results suggested that utilisation of IC in their current genetic merit and production environment is more profitable under FRS and SIS but not economically viable under IS.

Use of RNA amplification and electrophoresis for studying virus aerosol collection efficiency and their comparison with plaque assays.

PubMed

Jiang, Xiao; Pan, Maohua; Hering, Susanne V; Lednicky, John A; Wu, Chang-Yu; Fan, Z Hugh

2016-10-01

The spread of virus-induced infectious diseases through airborne routes of transmission is a global concern for economic and medical reasons. To study virus transmission, it is essential to have an effective aerosol collector such as the growth tube collector (GTC) system that utilizes water-based condensation for collecting virus-containing aerosols. In this work, we characterized the GTC system using bacteriophage MS2 as a surrogate for a small RNA virus. We investigated using RNA extraction and reverse transcription- polymerase chain reaction (RT-PCR) to study the total virus collection efficiency of the GTC system. Plaque assays were also used to enumerate viable viruses collected by the GTC system compared to that by a commercially available apparatus, the SKC® Biosampler. The plaque assay counts were used to enumerate viable viruses whereas RT-PCR provides a total virus count, including those viruses inactivated during collection. The effects of relative humidity (RH) and other conditions on collection efficiency were also investigated. Our results suggest that the GTC has a collection efficiency for viable viruses between 0.24 and 1.8% and a total virus collection efficiency between 18.3 and 79.0%, which is 1-2 orders of magnitude higher than that of the SKC® Biosampler. Moreover, higher RH significantly increases both the viable and total collection efficiency of the GTC, while its effect on the collection efficiency of the SKC® Biosampler is not significant. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Melimine-Coated Antimicrobial Contact Lenses Reduce Microbial Keratitis in an Animal Model.

PubMed

Dutta, Debarun; Vijay, Ajay K; Kumar, Naresh; Willcox, Mark D P

2016-10-01

To determine the ability of antimicrobial peptide melimine-coated contact lenses to reduce the incidence of microbial keratitis (MK) in a rabbit model of contact lens wear. In vitro antimicrobial activity of melimine-coated contact lenses was determined against Pseudomonas aeruginosa by viable count and a radiolabeled assay. The amount of lipopolysaccharide (LPS) associated with bacteria bound to melimine-coated and control lenses was determined. Ocular swabs from rabbit eyes were collected for assessment of ocular microflora. A rabbit model for MK was developed that used overnight wear of contact lenses colonized by P. aeruginosa in the absence of a corneal scratch. During lens wear, detailed ocular examinations were performed, and the incidence of MK was investigated. Bacteria associated with worn lenses and infected corneas were determined by viable plate count. Inhibition in viable and total P. aeruginosa adhesion by melimine-coated contact lenses was 3.1 log10 and 0.4 log10, respectively. After colonization, the amount of LPS on lenses was approximately the same with or without melimine. Gram-positive bacteria were found in all the ocular swabs followed by fungus (42%). Melimine-coated lens wear was protective and significantly (odds ratio 10.12; P = 0.012) reduced the incidence of P. aeruginosa-driven MK in the rabbit model. The antimicrobial lenses were associated with significantly (P < 0.001) lower ocular scores, indicating improved ocular signs compared with controls. This study showed that contaminated contact lenses can produce MK without corneal epithelial defect in an animal model. Melimine-coated contact lenses reduced the incidence of MK associated with P. aeruginosa in vivo. Development of MK requires viable bacteria adherent to contact lenses, and bacterial debris adherent at the lens surface did not cause keratitis.

Epilogue: Systems Approaches and Systems Practice

NASA Astrophysics Data System (ADS)

Reynolds, Martin; Holwell, Sue

Each of the five systems approaches discussed in this volume: system dynamics (SD), the viable systems model (VSM), strategic options development and analysis (SODA), soft systems methodology (SSM) and critical systems heuristics (CSH) has a pedigree. Not in the sense of the sometimes absurd spectacle of animals paraded at dog shows. Rather, their pedigree derives from their systems foundations, their capacity to evolve and their flexibility in use. None of the five approaches has developed out of use in restricted and controlled contexts of either low or high levels of complicatedness. Neither has any one of them evolved as a consequence of being applied only to situations with either presumed stakeholder agreement on purpose, or courteous disagreement amongst stakeholders, or stakeholder coercion. The compilation is not a celebration of abstract ‘methodologies', but of theoretically robust approaches that have a genuine pedigree in practice.

Snowball Earth: Skating on Thin Ice?

NASA Astrophysics Data System (ADS)

Roberson, A. L.; Stout, A. M.; Pollard, D.; Kasting, J. F.

2011-12-01

There is evidence of at least two intervals of widespread glaciation during the late Neoproterozoic (600-800 Myr ago), which are commonly referred to as "Snowball Earth" episodes. The global nature of these events is indicated by the fact that glacial deposits are found at low paleolatitudes during this time. Models of a global glacial event have produced a variety of solutions at low latitudes: thick ice, thin ice, slushball, and open ocean . The latter two models are similar, except that the slushball model has its ice-line at higher latitudes. To be viable, a model has to be able to account for the survival of life through the glaciations and also explain the existence of cap carbonates and other glacial debris deposited at low latitudes. The "thick-ice" model is not viable because kilometers of ice prevent the penetration of light necessary for the photosynthetic biota below. The "slushball" model is also not viable as it does not allow the formation of cap carbonates. The "thin-ice" model has been discussed previously and can account for continuation of photosynthetic life and glacial deposits at low paleolatitudes. The recently proposed "open-ocean" or "Jormungand" model also satisfies these requirements. What is it, though, that causes some models to produce thin ice near the equator and others to have open water there? We examine this question using a zonally symmetric energy balance climate model (EBM) with flowing sea glaciers to determine what parameter ranges produce each type of solution.

Modulation and modeling of monoclonal antibody N-linked glycosylation in mammalian cell perfusion reactors.

PubMed

Karst, Daniel J; Scibona, Ernesto; Serra, Elisa; Bielser, Jean-Marc; Souquet, Jonathan; Stettler, Matthieu; Broly, Hervé; Soos, Miroslav; Morbidelli, Massimo; Villiger, Thomas K

2017-09-01

Mammalian cell perfusion cultures are gaining renewed interest as an alternative to traditional fed-batch processes for the production of therapeutic proteins, such as monoclonal antibodies (mAb). The steady state operation at high viable cell density allows the continuous delivery of antibody product with increased space-time yield and reduced in-process variability of critical product quality attributes (CQA). In particular, the production of a confined mAb N-linked glycosylation pattern has the potential to increase therapeutic efficacy and bioactivity. In this study, we show that accurate control of flow rates, media composition and cell density of a Chinese hamster ovary (CHO) cell perfusion bioreactor allowed the production of a constant glycosylation profile for over 20 days. Steady state was reached after an initial transition phase of 6 days required for the stabilization of extra- and intracellular processes. The possibility to modulate the glycosylation profile was further investigated in a Design of Experiment (DoE), at different viable cell density and media supplement concentrations. This strategy was implemented in a sequential screening approach, where various steady states were achieved sequentially during one culture. It was found that, whereas high ammonia levels reached at high viable cell densities (VCD) values inhibited the processing to complex glycan structures, the supplementation of either galactose, or manganese as well as their synergy significantly increased the proportion of complex forms. The obtained experimental data set was used to compare the reliability of a statistical response surface model (RSM) to a mechanistic model of N-linked glycosylation. The latter outperformed the response surface predictions with respect to its capability and reliability in predicting the system behavior (i.e., glycosylation pattern) outside the experimental space covered by the DoE design used for the model parameter estimation. Therefore, we can conclude that the modulation of glycosylation in a sequential steady state approach in combination with mechanistic model represents an efficient and rational strategy to develop continuous processes with desired N-linked glycosylation patterns. Biotechnol. Bioeng. 2017;114: 1978-1990. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Performance and cost analysis of a structured concrete thermocline thermal energy storage system

NASA Astrophysics Data System (ADS)

Strasser, Matthew N.

Increasing global energy demands and diminishing fossil fuel resources have raised increased interest in harvesting renewable energy resources. Solar energy is a promising candidate, as sufficient irradiance is incident to the Earth to supply the energy demands of all of its inhabitants. At the utility scale, concentrating solar power (CSP) plants provide the most cost-efficient method of harnessing solar energy for conversion to electrical energy. A major roadblock to the large-scale implementation of CSP plants is the lack of thermal energy storage (TES) that would allow the continued production of electricity during the absence of constant irradiance. Sensible heat TES has been suggested as the most viable form of TES for CSP plants. Two-tank fluid TES systems have been incorporated at several CSP plants, significantly enhancing the performance of the plants. A single-tank thermocline TES system, requiring a reduced liquid media volume, has been suggested as a cost-reducing alternative. Unfortunately, the packed-aggregate bed of such TES system introduces the issue of thermal ratcheting and rupture of the tank's walls. To address this issue, it has been suggested that structured concrete be used in place of the aggregate bed. Potential concrete mix designs have been developed and tested for this application. Finite-difference-based numeric models are used to study the performance of packed-bed and structured concrete thermocline TES systems. Optimized models are developed for both thermocline configurations. The packed-bed thermocline model is used to determine whether or not assuming constant fluid properties over a temperature range is an acceptable assumption. A procedure is developed by which the cost of two-tank and single-tank thermocline TES systems in the capacity range of 100-3000 MWhe can be calculated. System Advisory Model is used to perform life-cycle cost and performance analysis of a central receiver plant incorporating four TES scenarios: no TES, two-tank TES, packed-bed thermocline TES, and structured concrete thermocline TES. Conclusions are drawn as to which form of TES provides the most viable option. Finally, concrete specimens cast from the aforementioned mix designs are tested in the presence of molten solar salt, and their applicability as structured filler material is assessed.

Strongly coupled gauge theories: What can lattice calculations teach us?

NASA Astrophysics Data System (ADS)

Hasenfratz, A.; Brower, R. C.; Rebbi, C.; Weinberg, E.; Witzel, O.

2017-12-01

The dynamical origin of electroweak symmetry breaking is an open question with many possible theoretical explanations. Strongly coupled systems predicting the Higgs boson as a bound state of a new gauge-fermion interaction form one class of candidate models. Due to increased statistics, LHC run II will further constrain the phenomenologically viable models in the near future. In the meanwhile it is important to understand the general properties and specific features of the different competing models. In this work we discuss many-flavor gauge-fermion systems that contain both massless (light) and massive fermions. The former provide Goldstone bosons and trigger electroweak symmetry breaking, while the latter indirectly influence the infrared dynamics. Numerical results reveal that such systems can exhibit a light 0++ isosinglet scalar, well separated from the rest of the spectrum. Further, when we set the scale via the vev of electroweak symmetry breaking, we predict a 2 TeV vector resonance which could be a generic feature of SU(3) gauge theories.

Fungal monitoring of the indoor air of the Museo de La Plata Herbarium, Argentina.

PubMed

Mallo, Andrea C; Elíades, Lorena A; Nitiu, Daniela S; Saparrat, Mario C N

Biological agents, such as fungal spores in the air in places where scientific collections are stored, can attack and deteriorate them. The aim of this study was to gather information on the indoor air quality of the Herbarium of Vascular Plants of the Museo de Ciencias Naturales de La Plata, Argentina, in relation to fungal propagules and inert particles. This study was made using a volumetric system and two complementary sampling methods: (1) a non-viable method for direct evaluation, and (2) a viable method by culture for viable fungal propagules. The non-viable method led to ten spore morphotypes being found from related fungal sources. A total of 4401.88spores/m 3 and 32135.18 inert suspended particles/m 3 were recorded. The viable method led to the finding of nine fungal taxa as viable spores that mostly belonged to anamorphic forms of Ascomycota, although the pigmented yeast Rhodotorula F.C. Harrison (Basidiomycota) was also found. A total count of 40,500fungal CFU/m 3 air was estimated for all the sites sampled. Both the non-viable and viable sampling methods were necessary to monitor the bio-aerosol load in the La Plata Herbarium. The indoor air of this institution seems to be reasonably adequate for the conservation of vascular plants due to the low indoor/outdoor index, low concentrations of air spores, and/or lack of indicators of moisture problems. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Two component Feebly Interacting Massive Particle (FIMP) dark matter

NASA Astrophysics Data System (ADS)

Pandey, Madhurima; Majumdar, Debasish; Prasad Modak, Kamakshya

2018-06-01

We explore the idea of an alternative candidate for particle dark matter namely Feebly Interacting Massive Particle (FIMP) in the framework of a two component singlet scalar model. Singlet scalar dark matter has already been demonstrated to be a viable candidate for WIMP (Weakly Interacting Massive Particle) dark matter in literature. In the FIMP scenario, dark matter particles are slowly produced via "thermal freeze-in" mechanism in the early Universe and are never abundant enough to reach thermal equilibrium or to undergo pair annihilation inside the Universe's plasma due to their extremely small couplings. We demonstrate that for smaller couplings too, required for freeze-in process, a two component scalar dark matter model considered here could well be a viable candidate for FIMP . In this scenario, the Standard Model of particle physics is extended by two gauge singlet real scalars whose stability is protected by an unbroken Z2× Z'2 symmetry and they are assumed to acquire no VEV after Spontaneous Symmetry Breaking. We explore the viable mass regions in the present two scalar DM model that is in accordance with the FIMP scenario. We also explore the upper limits of masses of the two components from the consideration of their self interactions.

Biology of the Coarse Aerosol Mode: Insights Into Urban Aerosol Ecology

NASA Astrophysics Data System (ADS)

Dueker, E.; O'Mullan, G. D.; Montero, A.

2015-12-01

Microbial aerosols have been understudied, despite implications for climate studies, public health, and biogeochemical cycling. Because viable bacterial aerosols are often associated with coarse aerosol particles, our limited understanding of the coarse aerosol mode further impedes our ability to develop models of viable bacterial aerosol production, transport, and fate in the outdoor environment, particularly in crowded urban centers. To address this knowledge gap, we studied aerosol particle biology and size distributions in a broad range of urban and rural settings. Our previously published findings suggest a link between microbial viability and local production of coarse aerosols from waterways, waste treatment facilities, and terrestrial systems in urban and rural environments. Both in coastal Maine and in New York Harbor, coarse aerosols and viable bacterial aerosols increased with increasing wind speeds above 4 m s-1, a dynamic that was observed over time scales ranging from minutes to hours. At a New York City superfund-designated waterway regularly contaminated with raw sewage, aeration remediation efforts resulted in significant increases of coarse aerosols and bacterial aerosols above that waterway. Our current research indicates that bacterial communities in aerosols at this superfund site have a greater similarity to bacterial communities in the contaminated waterway with wind speeds above 4 m s-1. Size-fractionated sampling of viable microbial aerosols along the urban waterfront has also revealed significant shifts in bacterial aerosols, and specifically bacteria associated with coarse aerosols, when wind direction changes from onshore to offshore. This research highlights the key connections between bacterial aerosol viability and the coarse aerosol fraction, which is important in assessments of production, transport, and fate of bacterial contamination in the urban environment.

Surfing on Protein Waves: Proteophoresis as a Mechanism for Bacterial Genome Partitioning

NASA Astrophysics Data System (ADS)

Walter, J.-C.; Dorignac, J.; Lorman, V.; Rech, J.; Bouet, J.-Y.; Nollmann, M.; Palmeri, J.; Parmeggiani, A.; Geniet, F.

2017-07-01

Efficient bacterial chromosome segregation typically requires the coordinated action of a three-component machinery, fueled by adenosine triphosphate, called the partition complex. We present a phenomenological model accounting for the dynamic activity of this system that is also relevant for the physics of catalytic particles in active environments. The model is obtained by coupling simple linear reaction-diffusion equations with a proteophoresis, or "volumetric" chemophoresis, force field that arises from protein-protein interactions and provides a physically viable mechanism for complex translocation. This minimal description captures most known experimental observations: dynamic oscillations of complex components, complex separation, and subsequent symmetrical positioning. The predictions of our model are in phenomenological agreement with and provide substantial insight into recent experiments. From a nonlinear physics view point, this system explores the active separation of matter at micrometric scales with a dynamical instability between static positioning and traveling wave regimes triggered by the dynamical spontaneous breaking of rotational symmetry.

From Patterns to Function in Living Systems: Dryland Ecosystems as a Case Study

NASA Astrophysics Data System (ADS)

Meron, Ehud

2018-03-01

Spatial patterns are ubiquitous in animate matter. Besides their intricate structure and beauty they generally play functional roles. The capacity of living systems to remain functional in changing environments is a question of utmost importance, but its intimate relationship to pattern formation is largely unexplored. Here, we address this relationship using dryland vegetation as a case study. Following a brief introduction to pattern-formation theory, we describe a mathematical model that captures several mechanisms of vegetation pattern formation and discuss ecological contexts that showcase different mechanisms. Using this model, we unravel the different vegetation patterns that keep dryland ecosystems viable along the rainfall gradient, identify multistability ranges where fronts separating domains of alternative stable states exist, and highlight the roles of front dynamics in mitigating or reversing desertification. The utility of satellite images in testing model predictions is discussed. An outlook on outstanding open problems concludes this paper.

A MODEL SYSTEM TO STUDY ANTIMICROBIAL STRATEGIES IN ENDODONTIC BIOFILMS

PubMed Central

Estrela, Carlos; Sydney, Gilson Blitzkow; Figueiredo, José Antonio Poli; Estrela, Cyntia Rodrigues de Araújo

2009-01-01

The purpose of this work was to develop a model system to study antimicrobial strategies in endodontic biofilms. Enterococcus faecalis suspension was colonized in 10 human root canals. Five milliliters of Brain Heart Infusion (BHI) were mixed with 5 mL of the bacterial inoculums (E. faecalis) and inoculated with sufficient volume to fill the root canal during 60 days. This procedure was repeated every 72 h, always using 24-h pure culture prepared and adjusted to No. 1 MacFarland turbidity standard. Biofilm formation was analyzed by scanning electron microscopy (SEM). E. faecalis consistently adhered to collagen structure, colonized dentin surface, progressed towards the dentinal tubules and formed a biofilm. The proposed biofilm model seems to be viable for studies on antimicrobial strategies, and allows for a satisfactory colonization time of selected bacterial species with virulence and adherence properties. PMID:19274391

Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.

PubMed

Capozziello, S; Lambiase, G; Saridakis, E N

2017-01-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.

Extending and expanding the life of older current meters

USGS Publications Warehouse

Strahle, W.J.; Martini, Marinna A.

1995-01-01

The EG&G Model 610 VACM and Model 630 VMCM are standards for ocean current measurements. It is simple to add peripheral sensors to the data stream of the VACM by use of add-on CMOS circuitry. The firmware control of the VMCM makes it virtually impossible to add sampling of additional sensors. Most of the electronic components used in the VACM are obsolete or difficult to replace and the VMCM will soon follow suit. As a result, the USGS joined WHOI in the development of a PCMCIA data storage system to replace the cassette recording system in the VACM. Using the same PCMCIA recording package as the controller and recorder for the VMCM, a user-friendly VMCM is being designed. PCMCIA cards are rapidly becoming an industry standard with a wide range of storage capacities. By upgrading the VACM and VMCM to PCMCIA storage systems with a flexible microprocessor, they will continue to be viable instruments.

Evaluation of the Universal Viral Transport system for long-term storage of virus specimens for microbial forensics.

PubMed

Hosokawa-Muto, Junji; Fujinami, Yoshihito; Mizuno, Natsuko

2015-08-01

Forensic microbial specimens, including bacteria and viruses, are collected at biocrime and bioterrorism scenes. Although it is preferable that the pathogens in these samples are alive and kept in a steady state, the samples may be stored for prolonged periods before analysis. Therefore, it is important to understand the effects of storage conditions on the pathogens contained within such samples. To evaluate the capacity to preserve viable virus and the viral genome, influenza virus was added to the transport medium of the Universal Viral Transport system and stored for over 3 months at various temperatures, after which virus titrations and quantitative analysis of the influenza hemagglutinin gene were performed. Although viable viruses became undetectable 29 days after the medium was stored at room temperature, viruses in the medium stored at 4°C were viable even after 99 days. A quantitative PCR analysis indicated that the hemagglutinin gene was maintained for 99 days at both 4°C and room temperature. Therefore, long-term storage at 4°C has little effect on viable virus and viral genes, so the Universal Viral Transport system can be useful for microbial forensics. This study provides important information for the handling of forensic virus specimens. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

The utilization of nonterrestrial materials. [resources for solar power satellite construction

NASA Technical Reports Server (NTRS)

1981-01-01

The development of research and technology programs on the user of nonterrestrial materials for space applications was considered with emphasis on the space power satellite system as a model of large space systems for which the use of nonterrestrial materials may be economically viable. Sample topics discussed include the mining of raw materials and the conversion of raw materials into useful products. These topics were considered against a background of the comparative costs of using terrestrial materials. Exploratory activities involved in the preparation of a nonterrestrial materials utilization program, and the human factors involved were also addressed. Several recommendations from the workshop are now incorporated in NASA activities.

Cassette bacteria detection system. [for monitoring the sterility of regenerated water in spacecraft

NASA Technical Reports Server (NTRS)

1974-01-01

The design, fabrication, and testing of an automatic bacteria detection system, with a zero-g capability, based on the filter-capable approach, and intended for monitoring the sterility of regenerated water in spacecraft is discussed. The principle of detection is based on measuring the increase in chemiluminescence produced by the action of bacterial porphyrins on a luminol-hydrogen peroxide mixture. Viable organisms are detected by comparing the signal of an incubated water sample with an unincubated control. High signals for the incubated water sample indicate the presence of viable organisms.

A new analytical platform based on field-flow fractionation and olfactory sensor to improve the detection of viable and non-viable bacteria in food.

PubMed

Roda, Barbara; Mirasoli, Mara; Zattoni, Andrea; Casale, Monica; Oliveri, Paolo; Bigi, Alessandro; Reschiglian, Pierluigi; Simoni, Patrizia; Roda, Aldo

2016-10-01

An integrated sensing system is presented for the first time, where a metal oxide semiconductor sensor-based electronic olfactory system (MOS array), employed for pathogen bacteria identification based on their volatile organic compound (VOC) characterisation, is assisted by a preliminary separative technique based on gravitational field-flow fractionation (GrFFF). In the integrated system, a preliminary step using GrFFF fractionation of a complex sample provided bacteria-enriched fractions readily available for subsequent MOS array analysis. The MOS array signals were then analysed employing a chemometric approach using principal components analysis (PCA) for a first-data exploration, followed by linear discriminant analysis (LDA) as a classification tool, using the PCA scores as input variables. The ability of the GrFFF-MOS system to distinguish between viable and non-viable cells of the same strain was demonstrated for the first time, yielding 100 % ability of correct prediction. The integrated system was also applied as a proof of concept for multianalyte purposes, for the detection of two bacterial strains (Escherichia coli O157:H7 and Yersinia enterocolitica) simultaneously present in artificially contaminated milk samples, obtaining a 100 % ability of correct prediction. Acquired results show that GrFFF band slicing before MOS array analysis can significantly increase reliability and reproducibility of pathogen bacteria identification based on their VOC production, simplifying the analytical procedure and largely eliminating sample matrix effects. The developed GrFFF-MOS integrated system can be considered a simple straightforward approach for pathogen bacteria identification directly from their food matrix. Graphical abstract An integrated sensing system is presented for pathogen bacteria identification in food, in which field-flow fractionation is exploited to prepare enriched cell fractions prior to their analysis by electronic olfactory system analysis.

Very low scale Coleman-Weinberg inflation with nonminimal coupling

NASA Astrophysics Data System (ADS)

Kaneta, Kunio; Seto, Osamu; Takahashi, Ryo

2018-03-01

We study viable small-field Coleman-Weinberg (CW) inflation models with the help of nonminimal coupling to gravity. The simplest small-field CW inflation model (with a low-scale potential minimum) is incompatible with the cosmological constraint on the scalar spectral index. However, there are possibilities to make the model realistic. First, we revisit the CW inflation model supplemented with a linear potential term. We next consider the CW inflation model with a logarithmic nonminimal coupling and illustrate that the model can open a new viable parameter space that includes the model with a linear potential term. We also show parameter spaces where the Hubble scale during the inflation can be as small as 10-4 GeV , 1 GeV, 1 04 GeV , and 1 08 GeV for the number of e -folds of 40, 45, 50, and 55, respectively, with other cosmological constraints being satisfied.

Total and Viable Legionella pneumophila Cells in Hot and Natural Waters as Measured by Immunofluorescence-Based Assays and Solid-Phase Cytometry ▿†

PubMed Central

Parthuisot, N.; Binet, M.; Touron-Bodilis, A.; Pougnard, C.; Lebaron, P.; Baudart, J.

2011-01-01

A new method was developed for the rapid and sensitive detection of viable Legionella pneumophila. The method combines specific immunofluorescence (IF) staining using monoclonal antibodies with a bacterial viability marker (ChemChrome V6 cellular esterase activity marker) by means of solid-phase cytometry (SPC). IF methods were applied to the detection and enumeration of both the total and viable L. pneumophila cells in water samples. The sensitivity of the IF methods coupled to SPC was 34 cells liter−1, and the reproducibility was good, with the coefficient of variation generally falling below 30%. IF methods were applied to the enumeration of total and viable L. pneumophila cells in 46 domestic hot water samples as well as in cooling tower water and natural water samples, such as thermal spring water and freshwater samples. Comparison with standard plate counts showed that (i) the total direct counts were always higher than the plate counts and (ii) the viable counts were higher than or close to the plate counts. With domestic hot waters, when the IF assay was combined with the viability test, SPC detected up to 3.4 × 103 viable but nonculturable L. pneumophila cells per liter. These direct IF methods could be a powerful tool for high-frequency monitoring of domestic hot waters or for investigating the occurrence of viable L. pneumophila in both man-made water systems and environmental water samples. PMID:21742913

Flight Control Design for an Autonomous Rotorcraft Using Pseudo-Sliding Mode Control and Waypoint Navigation

NASA Astrophysics Data System (ADS)

Mallory, Nicolas Joseph

The design of robust automated flight control systems for aircraft of varying size and complexity is a topic of continuing interest for both military and civilian industries. By merging the benefits of robustness from sliding mode control (SMC) with the familiarity and transparency of design tradeoff offered by frequency domain approaches, this thesis presents pseudo-sliding mode control as a viable option for designing automated flight control systems for complex six degree-of-freedom aircraft. The infinite frequency control switching of SMC is replaced, by necessity, with control inputs that are continuous in nature. An introduction to SMC theory is presented, followed by a detailed design of a pseudo-sliding mode control and automated flight control system for a six degree-of-freedom model of a Hughes OH6 helicopter. This model is then controlled through three different waypoint missions that demonstrate the stability of the system and the aircraft's ability to follow certain maneuvers despite time delays, large changes in model parameters and vehicle dynamics, actuator dynamics, sensor noise, and atmospheric disturbances.

Architecture Studies for Commercial Production of Propellants From the Lunar Poles

NASA Astrophysics Data System (ADS)

Duke, Michael B.; Diaz, Javier; Blair, Brad R.; Oderman, Mark; Vaucher, Marc

2003-01-01

Two architectures are developed that could be used to convert water held in regolith deposits within permanently shadowed lunar craters into propellant for use in near-Earth space. In particular, the model has been applied to an analysis of the commercial feasibility of using lunar derived propellant to convey payloads from low Earth orbit to geosynchronous Earth orbit. Production and transportation system masses were estimated for each architecture and cost analysis was made using the NAFCOM cost model. Data from the cost model were analyzed using a financial analysis tool reported in a companion paper (Lamassoure et al., 2002) to determine under what conditions the architectures might be commercially viable. Analysis of the architectural assumptions is used to identify the principal areas for further research, which include technological development of lunar mining and water extraction systems, power systems, reusable space transportation systems, and orbital propellant depots. The architectures and commercial viability are sensitive to the assumed concentration of ice in the lunar deposits, suggesting that further lunar exploration to determine whether higher-grade deposits exist would be economically justified.

2-D Fused Image Reconstruction approach for Microwave Tomography: a theoretical assessment using FDTD Model

PubMed Central

Bindu, G.; Semenov, S.

2013-01-01

This paper describes an efficient two-dimensional fused image reconstruction approach for Microwave Tomography (MWT). Finite Difference Time Domain (FDTD) models were created for a viable MWT experimental system having the transceivers modelled using thin wire approximation with resistive voltage sources. Born Iterative and Distorted Born Iterative methods have been employed for image reconstruction with the extremity imaging being done using a differential imaging technique. The forward solver in the imaging algorithm employs the FDTD method of solving the time domain Maxwell’s equations with the regularisation parameter computed using a stochastic approach. The algorithm is tested with 10% noise inclusion and successful image reconstruction has been shown implying its robustness. PMID:24058889

Supercapacitor to Provide Ancillary Services: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muljadi, Eduard; Gevorgian, Vahan; Luo, Yusheng

Supercapacitor technology has reached a level of maturity as a viable energy storage option available to support a modern electric power system grid; however, its application is still limited because of its energy capacity and the cost of the commercial product. In this paper, we demonstrate transient models of supercapacitor energy storage plants operating in coordination with run-of-the-river (ROR), doubly-fed induction generator hydropower plants (HPP) using a system control concept and architecture developed. A detailed transient model of a supercapacitor energy storage device is coupled with the grid via a three-phase inverter/rectifier and bidirectional DC-DC converter. In addition, we usemore » a version of a 14-bus IEEE test case that includes the models of the supercapacitor energy storage device, ROR HPPs, and synchronous condensers that use the rotating synchronous generators of retired coal-powered plants. The purpose of the synchronous condensers is to enhance the system stability by providing voltage and reactive power control, provide power system oscillations damping, and maintain system inertia at secure levels. The control layer provides coordinated, decentralized operation of distributed ROR HPPs and energy storage as aggregate support to power system operations.« less

Hybrid feedforward and feedback controller design for nuclear steam generators over wide range operation using genetic algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Y.; Edwards, R.M.; Lee, K.Y.

1997-03-01

In this paper, a simplified model with a lower order is first developed for a nuclear steam generator system and verified against some realistic environments. Based on this simplified model, a hybrid multi-input and multi-out (MIMO) control system, consisting of feedforward control (FFC) and feedback control (FBC), is designed for wide range conditions by using the genetic algorithm (GA) technique. The FFC control, obtained by the GA optimization method, injects an a priori command input into the system to achieve an optimal performance for the designed system, while the GA-based FBC control provides the necessary compensation for any disturbances ormore » uncertainties in a real steam generator. The FBC control is an optimal design of a PI-based control system which would be more acceptable for industrial practices and power plant control system upgrades. The designed hybrid MIMO FFC/FBC control system is first applied to the simplified model and then to a more complicated model with a higher order which is used as a substitute of the real system to test the efficacy of the designed control system. Results from computer simulations show that the designed GA-based hybrid MIMO FFC/FBC control can achieve good responses and robust performances. Hence, it can be considered as a viable alternative to the current control system upgrade.« less

Interacting dark energy: Dynamical system analysis

NASA Astrophysics Data System (ADS)

Golchin, Hanif; Jamali, Sara; Ebrahimi, Esmaeil

We investigate the impacts of interaction between dark matter (DM) and dark energy (DE) in the context of two DE models, holographic (HDE) and ghost dark energy (GDE). In fact, using the dynamical system analysis, we obtain the cosmological consequence of several interactions, considering all relevant component of universe, i.e. matter (dark and luminous), radiation and DE. Studying the phase space for all interactions in detail, we show the existence of unstable matter-dominated and stable DE-dominated phases. We also show that linear interactions suffer from the absence of standard radiation-dominated epoch. Interestingly, this failure resolved by adding the nonlinear interactions to the models. We find an upper bound for the value of the coupling constant of the interaction between DM and DE as b < 0.57in the case of holographic model, and b < 0.61 in the case of GDE model, to result in a cosmological viable matter-dominated epoch. More specifically, this bound is vital to satisfy instability and deceleration of matter-dominated epoch.

Parasites in soil/sludge systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandon, J.R.

1978-03-01

The potential for the transmission of parasites, such as Entamoeba sp., schistosomes, and nematodes such as Ascaris sp., to man through the use of sewage sludges as fertilizer is reviewed. The eggs of Ascaris have been found to be the most resistant of these parasites to normal sludge treatment methods. Results of studies on the effectiveness of heat and ionizing radiation treatments reported show that a treatment of 55/sup 0/C for 1 hour or more sufficiently reduces the number of viable Ascaris eggs in seeded sludge systems. An absorbed dose of 300 kilorads radiation is more than adequate for themore » same purpose. However, before an unequivocal statement can be made about the effectiveness of either of these treatments in reducing viable ova in real systems, certain qualifying factors must be investigated. There are conflicting reports on the radiation sensitivities of Ascaris eggs in different stages of development. Also, irradiation of composted sludge using an electron beam was unsuccessful in rendering all naturally-occurring Ascaris ova non-viable, even at 300 kilorads. The significant differences in radiation and heat sensitivities of Ascaris eggs in compost vs liquid systems points out the need to further investigate the effects of moisture levels on these sensitivities.« less

Tape Cassette Bacteria Detection System

NASA Technical Reports Server (NTRS)

1973-01-01

The design, fabrication, and testing of an automatic bacteria detection system with a zero-g capability and based on the filter-capsule approach is described. This system is intended for monitoring the sterility of regenerated water in a spacecraft. The principle of detection is based on measuring the increase in chemiluminescence produced by the action of bacterial porphyrins (i.e., catalase, cytochromes, etc.) on a luminol-hydrogen peroxide mixture. Since viable as well as nonviable organisms initiate this luminescence, viable organisms are detected by comparing the signal of an incubated water sample with an unincubated control. Higher signals for the former indicate the presence of viable organisms. System features include disposable sealed sterile capsules, each containing a filter membrane, for processing discrete water samples and a tape transport for moving these capsules through a processing sequence which involves sample concentration, nutrient addition, incubation, a 4 Molar Urea wash and reaction with luminol-hydrogen peroxide in front of a photomultiplier tube. Liquids are introduced by means of a syringe needle which pierces a rubber septum contained in the wall of the capsule. Detection thresholds obtained with this unit towards E. coli and S. marcescens assuming a 400 ml water sample are indicated.

Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports

NASA Technical Reports Server (NTRS)

Jansen, Ralph H.; Bowman, Cheryl; Jankovsky, Amy; Dyson, Rodger; Felder, James L.

2017-01-01

NASA is investing in Electrified Aircraft Propulsion (EAP) research as part of the portfolio to improve the fuel efficiency, emissions, and noise levels in commercial transport aircraft. Turboelectric, partially turboelectric, and hybrid electric propulsion systems are the primary EAP configurations being evaluated for regional jet and larger aircraft. The goal is to show that one or more viable EAP concepts exist for narrow body aircraft and mature tall-pole technologies related to those concepts. A summary of the aircraft system studies, technology development, and facility development is provided. The leading concept for mid-term (2035) introduction of EAP for a single aisle aircraft is a tube and wing, partially turbo electric configuration (STARC-ABL), however other viable configurations exist. Investments are being made to raise the TRL (Technology Readiness Level) level of light weight, high efficiency motors, generators, and electrical power distribution systems as well as to define the optimal turbine and boundary layer ingestion systems for a mid-term tube and wing configuration. An electric aircraft power system test facility (NEAT - NASA’s Electric Aircraft Testbed) is under construction at NASA Glenn and an electric aircraft control system test facility (HEIST - Hybrid-Electric Integrated Systems Testbed) is under construction at NASA Armstrong. The correct building blocks are in place to have a viable, large plane EAP configuration tested by 2025 leading to entry into service in 2035 if the community chooses to pursue that goal.

Building intelligent communication systems for handicapped aphasiacs.

PubMed

Fu, Yu-Fen; Ho, Cheng-Seen

2010-01-01

This paper presents an intelligent system allowing handicapped aphasiacs to perform basic communication tasks. It has the following three key features: (1) A 6-sensor data glove measures the finger gestures of a patient in terms of the bending degrees of his fingers. (2) A finger language recognition subsystem recognizes language components from the finger gestures. It employs multiple regression analysis to automatically extract proper finger features so that the recognition model can be fast and correctly constructed by a radial basis function neural network. (3) A coordinate-indexed virtual keyboard allows the users to directly access the letters on the keyboard at a practical speed. The system serves as a viable tool for natural and affordable communication for handicapped aphasiacs through continuous finger language input.

A class of simple bouncing and late-time accelerating cosmologies in f(R) gravity

NASA Astrophysics Data System (ADS)

Kuiroukidis, A.

We consider the field equations for a flat FRW cosmological model, given by Eq. (??), in an a priori generic f(R) gravity model and cast them into a, completely normalized and dimensionless, system of ODEs for the scale factor and the function f(R), with respect to the scalar curvature R. It is shown that under reasonable assumptions, namely for power-law functional form for the f(R) gravity model, one can produce simple analytical and numerical solutions describing bouncing cosmological models where in addition there are late-time accelerating. The power-law form for the f(R) gravity model is typically considered in the literature as the most concrete, reasonable, practical and viable assumption [see S. D. Odintsov and V. K. Oikonomou, Phys. Rev. D 90 (2014) 124083, arXiv:1410.8183 [gr-qc

Engineering of mechanical manufacturing from the cradle to cradle

NASA Astrophysics Data System (ADS)

Peralta, M. E.; Aguayo, F.; Lama, J. R.

2012-04-01

The sustainability of manufacturing processes lies in industrial planning and productive activity. Industrial plants are characterized by the management of resource (inputs and outputs), processing and conversion processes, which usually are organized in a linear system. Good planning will optimize the manufacturing and promoting the quality of the industrial system. Cradle to Cradle is a new paradigm for engineering and sustainable manufacturing that integrates projects (industrial parks, manufacturing plants, systems and products) in a framework consistent with the environment, adapted to the society and technology and economically viable. To carry it out, we implement this paradigm in the MGE2 (Genomic Model of Eco-innovation and Eco-design), as a methodology for designing and developing products and manufacturing systems with an approach from the cradle to cradle.

Heuristics Applied in the Development of Advanced Space Mission Concepts

NASA Technical Reports Server (NTRS)

Nilsen, Erik N.

1998-01-01

Advanced mission studies are the first step in determining the feasibility of a given space exploration concept. A space scientist develops a science goal in the exploration of space. This may be a new observation method, a new instrument or a mission concept to explore a solar system body. In order to determine the feasibility of a deep space mission, a concept study is convened to determine the technology needs and estimated cost of performing that mission. Heuristics are one method of defining viable mission and systems architectures that can be assessed for technology readiness and cost. Developing a viable architecture depends to a large extent upon extending the existing body of knowledge, and applying it in new and novel ways. These heuristics have evolved over time to include methods for estimating technical complexity, technology development, cost modeling and mission risk in the unique context of deep space missions. This paper examines the processes involved in performing these advanced concepts studies, and analyzes the application of heuristics in the development of an advanced in-situ planetary mission. The Venus Surface Sample Return mission study provides a context for the examination of the heuristics applied in the development of the mission and systems architecture. This study is illustrative of the effort involved in the initial assessment of an advance mission concept, and the knowledge and tools that are applied.

Naturalistic Decision Making for Power System Operators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greitzer, Frank L.; Podmore, Robin; Robinson, Marck

2010-02-01

Motivation – Investigations of large-scale outages in the North American interconnected electric system often attribute the causes to three T’s: Trees, Training and Tools. To document and understand the mental processes used by expert operators when making critical decisions, a naturalistic decision making (NDM) model was developed. Transcripts of conversations were analyzed to reveal and assess NDM-based performance criteria. Findings/Design – An item analysis indicated that the operators’ Situation Awareness Levels, mental models, and mental simulations can be mapped at different points in the training scenario. This may identify improved training methods or analytical/ visualization tools. Originality/Value – This studymore » applies for the first time, the concepts of Recognition Primed Decision Making, Situation Awareness Levels and Cognitive Task Analysis to training of electric power system operators. Take away message – The NDM approach provides a viable framework for systematic training management to accelerate learning in simulator-based training scenarios for power system operators and teams.« less

Understanding molecular motor walking along a microtubule: a themosensitive asymmetric Brownian motor driven by bubble formation.

PubMed

Arai, Noriyoshi; Yasuoka, Kenji; Koishi, Takahiro; Ebisuzaki, Toshikazu; Zeng, Xiao Cheng

2013-06-12

The "asymmetric Brownian ratchet model", a variation of Feynman's ratchet and pawl system, is invoked to understand the kinesin walking behavior along a microtubule. The model system, consisting of a motor and a rail, can exhibit two distinct binding states, namely, the random Brownian state and the asymmetric potential state. When the system is transformed back and forth between the two states, the motor can be driven to "walk" in one direction. Previously, we suggested a fundamental mechanism, that is, bubble formation in a nanosized channel surrounded by hydrophobic atoms, to explain the transition between the two states. In this study, we propose a more realistic and viable switching method in our computer simulation of molecular motor walking. Specifically, we propose a thermosensitive polymer model with which the transition between the two states can be controlled by temperature pulses. Based on this new motor system, the stepping size and stepping time of the motor can be recorded. Remarkably, the "walking" behavior observed in the newly proposed model resembles that of the realistic motor protein. The bubble formation based motor not only can be highly efficient but also offers new insights into the physical mechanism of realistic biomolecule motors.

A measurement system for large, complex software programs

NASA Technical Reports Server (NTRS)

Rone, Kyle Y.; Olson, Kitty M.; Davis, Nathan E.

1994-01-01

This paper describes measurement systems required to forecast, measure, and control activities for large, complex software development and support programs. Initial software cost and quality analysis provides the foundation for meaningful management decisions as a project evolves. In modeling the cost and quality of software systems, the relationship between the functionality, quality, cost, and schedule of the product must be considered. This explicit relationship is dictated by the criticality of the software being developed. This balance between cost and quality is a viable software engineering trade-off throughout the life cycle. Therefore, the ability to accurately estimate the cost and quality of software systems is essential to providing reliable software on time and within budget. Software cost models relate the product error rate to the percent of the project labor that is required for independent verification and validation. The criticality of the software determines which cost model is used to estimate the labor required to develop the software. Software quality models yield an expected error discovery rate based on the software size, criticality, software development environment, and the level of competence of the project and developers with respect to the processes being employed.

Solar energy system economic evaluation: IBM System 2, Togus, Maine

NASA Technical Reports Server (NTRS)

1980-01-01

The economic analysis of the solar energy system, is developed for Torgus and four other sites typical of a wide range of environmental and economic conditions in the continental United States. This analysis is accomplished based on the technical and economic models in the f-chart design procedure with inputs taken on the characteristics of the installed system and local conditions. The results are expressed in terms of the economic parameters of present worth of system cost over a projected twenty year life, life cycle savings, year of positive savings and year of payback for the optimized solar energy system at each of the analysis sites. The sensitivity of the economic evaluation to uncertainties in constituent system and economic variables is also investigated. Results demonstrate that the solar energy system is economically viable at all of the five sites for which the analysis was conducted.

The potential of 5-fluorocytosine/cytosine deaminase enzyme prodrug gene therapy in an intrahepatic colon cancer model.

PubMed

Nyati, M K; Symon, Z; Kievit, E; Dornfeld, K J; Rynkiewicz, S D; Ross, B D; Rehemtulla, A; Lawrence, T S

2002-07-01

Colorectal cancer can metastasize to the liver, but remain liver confined for years. A critical step in developing treatments for intrahepatic cancer involves assessment in an orthotopic intrahepatic model. The purpose of this study was to develop a noninvasive intrahepatic tumor model to study the efficacy of 5-flucytosine/yeast cytosine deaminase (5FC/yCD)-based gene therapy for liver tumors. Luciferase expressing human colorectal carcinoma (HT-29luc) cells were generated by retroviral infection and implanted in the left liver lobe of nude mice. The bioluminescence was measured every week for a period of 1 month, then animals were killed and tumors were measured by calipers. After we found a correlation between photon counts and tumor size, animals were implanted with tumors composed of either 0%, 10%, or 100% yCD/HT-29luc cells, and treated with 5FC. Tumor bioluminescence was measured during treatment and tumor histology examined at the time of death. We found that 5FC caused significant regression of yCD expressing tumors. Furthermore, visible tumors at the time of death, which emitted little bioluminescence, contained little or no viable tumor. We then developed an adenoviral vector for yCD. Intraperitoneal administration of adenovirus containing yCD led to the production of yCD enzyme within intrahepatic tumors. These results suggest that (1) intrahepatic cancer responds to 5FC when cells express yCD; (2) the luciferin-luciferase system permits non-invasive real time imaging of viable intrahepatic cancer; and (3) this system can be used to carry out gene therapy experiments using yCD adenovirus.

Development of a Twin-Spool Turbofan Engine Simulation Using the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS)

NASA Technical Reports Server (NTRS)

Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Jonathan S.

2014-01-01

The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3% of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.

On the self-serving function of an academic wooden leg: test anxiety as a self-handicapping strategy.

PubMed

Smith, C W; Snyder, D R; Handelsman, M M

1982-02-01

The present study investigated the hypothesis that psychological symptoms may serve a self-protective function by providing an alternative explanation for potential failure in evaluating situations. It was hypothesized that highly test-anxious subjects would report anxiety symptoms in a pattern that reflected strategic presentation of symptoms; more specifically, it was predicted that greater reported anxiety should result when anxiety was a viable explanation for poor performance on an intelligence test and that lower reported anxiety should result when anxiety was not a viable explanation for poor performance. Analysis of state measures of self-reported anxiety supported these predictions. Further analysis indicated that when anxiety was not a viable explanation for poor test performance, high test-anxiety subjects reported reduced effort as an alternative self-protective strategy. These results are discussed in terms of traditional models of symptoms as self-protective strategies, current social psychological models of symptoms, and in reference to recent theory and research about the nature and treatment of test anxiety.

Fate of Large-Scale Structure in Modified Gravity After GW170817 and GRB170817A

NASA Astrophysics Data System (ADS)

Amendola, Luca; Kunz, Martin; Saltas, Ippocratis D.; Sawicki, Ignacy

2018-03-01

The coincident detection of gravitational waves (GW) and a gamma-ray burst from a merger of neutron stars has placed an extremely stringent bound on the speed of GWs. We showed previously that the presence of gravitational slip (η ) in cosmology is intimately tied to modifications of GW propagation. This new constraint implies that the only remaining viable source of gravitational slip is a conformal coupling to gravity in scalar-tensor theories, while viable vector-tensor theories cannot now generate gravitational slip at all. We discuss structure formation in the remaining viable models, demonstrating that (i) the dark-matter growth rate must now be at least as fast as in general relativity (GR), with the possible exception of that beyond the Horndeski model, and (ii) if there is any scale dependence at all in the slip parameter, it is such that it takes the GR value at large scales. We show a consistency relation that must be violated if gravity is modified.

Activity of AFN-1252, a novel FabI inhibitor, against Staphylococcus aureus in an in vitro pharmacodynamic model simulating human pharmacokinetics

PubMed Central

Tsuji, Brian T; Harigaya, Yoriko; Lesse, Alan J; Forrest, Alan; Ngo, Dung

2013-01-01

AFN-1252, a potent enoyl-ACP reductase (FabI) inhibitor, is under development for the treatment of Staphylococcus aureus infections. The activity of AFN-1252 against two isolates of S. aureus, MSSA 26213 and MRSA S186, was studied in an in vitro pharmacodynamic model simulating AFN-1252 pharmacokinetics in man. Reductions in bacterial viable count over the first 6 hours were generally 1–2 logs and maximal reductions in viable count were generally achieved at fAUC/MIC ratios of 100–200. Maximum reductions in viable count against MSSA 29213 and MRSA S186 were approximately 4 logs, achieved by 450 mg q12h (fAUC/MIC = 1875) dosing at 28 hours. Staphylococcal resistance to AFN-1252 did not develop throughout the 48-hour experiments. As multidrug resistance continues to increase, these studies support the continued investigation of AFN-1252 as a targeted therapeutic for staphylococcal infections. PMID:23433442

Plant Seeds as Model Vectors for the Transfer of Life Through Space

NASA Astrophysics Data System (ADS)

Tepfer, David; Leach, Sydney

2006-12-01

We consider plant seeds as terrestrial models for a vectored life form that could protect biological information in space. Seeds consist of maternal tissue surrounding and protecting an embryo. Some seeds resist deleterious conditions found in space: ultra low vacuum, extreme temperatures and radiation, including intense UV light. In a receptive environment, seeds could liberate a viable embryo, viable higher cells or a viable free-living organism (an endosymbiont or endophyte). Even if viability is lost, seeds still contain functional macro and small molecules (DNA, RNA, proteins, amino acids, lipids, etc.) that could provide the chemical basis for starting or modifying life. The possible release of endophytes or endosymbionts from a seed-like space traveler suggests that multiple domains of life, defined in DNA sequence phylogenies, could be disseminated simultaneously from Earth. We consider the possibility of exospermia, the outward transfer of life, as well as introspermia, the inward transfer of life-both as a contemporary and ancient events.

Swirl Flow Bioreactor coupled with Cu-alginate beads: A system for the eradication of Coliform and Escherichia coli from biological effluents.

PubMed

Atkinson, Sov; Thomas, Simon F; Goddard, Paul; Bransgrove, Rachel M; Mason, Paul T; Oak, Ajeet; Bansode, Anand; Patankar, Rohit; Gleason, Zachary D; Sim, Marissa K; Whitesell, Andrew; Allen, Michael J

2015-05-21

It is estimated that approximately 1.1 billion people globally drink unsafe water. We previously reported both a novel copper-alginate bead, which quickly reduces pathogen loading in waste streams and the incorporation of these beads into a novel swirl flow bioreactor (SFB), of low capital and running costs and of simple construction from commercially available plumbing pipes and fittings. The purpose of the present study was to trial this system for pathogen reduction in waste streams from an operating Dewats system in Hinjewadi, Pune, India and in both simulated and real waste streams in Seattle, Washington, USA. The trials in India, showed a complete inactivation of coliforms in the discharged effluent (Mean Log removal Value (MLRV) = 3.51), accompanied by a total inactivation of E. coli with a MLRV of 1.95. The secondary clarifier effluent also showed a 4.38 MLRV in viable coliforms during treatment. However, the system was slightly less effective in reducing E. coli viability, with a MLRV of 1.80. The trials in Seattle also demonstrated the efficacy of the system in the reduction of viable bacteria, with a LRV of 5.67 observed of viable Raoultella terrigena cells (100%).

Spherical cows in the sky with fab four

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaloper, Nemanja; Sandora, McCullen, E-mail: kaloper@physics.ucdavis.edu, E-mail: mesandora@ucdavis.edu

2014-05-01

We explore spherically symmetric static solutions in a subclass of unitary scalar-tensor theories of gravity, called the 'Fab Four' models. The weak field large distance solutions may be phenomenologically viable, but only if the Gauss-Bonnet term is negligible. Only in this limit will the Vainshtein mechanism work consistently. Further, classical constraints and unitarity bounds constrain the models quite tightly. Nevertheless, in the limits where the range of individual terms at large scales is respectively Kinetic Braiding, Horndeski, and Gauss-Bonnet, the horizon scale effects may occur while the theory satisfies Solar system constraints and, marginally, unitarity bounds. On the other hand,more » to bring the cutoff down to below a millimeter constrains all the couplings scales such that 'Fab Fours' can't be heard outside of the Solar system.« less

An experimental approach towards the development of an in vitro cortical-thalamic co-culture model.

PubMed

Kanagasabapathi, Thirukumaran T; Massobrio, Paolo; Tedesco, Mariateresa; Martinoia, Sergio; Wadman, Wytse J; Decré, Michel M J

2011-01-01

In this paper, we propose an experimental approach to develop an in vitro dissociated cortical-thalamic co-culture model using a dual compartment neurofluidic device. The device has two compartments separated by 10 μm wide and 3 μm high microchannels. The microchannels provide a physical isolation of neurons allowing only neurites to grow between the compartments. Long-term viable co-culture was maintained in the compartmented device, neurite growth through the microchannels was verified using immunofluorescence staining, and electrophysiological recordings from the co-culture system was investigated. Preliminary analysis of spontaneous activities from the co-culture shows a distinctively different firing pattern associated with cultures of individual cell types and further analysis is proposed for a deeper understanding of the dynamics involved in the network connectivity in such a co-culture system.

Design and testing of an oblique all-wing supersonic transport

NASA Technical Reports Server (NTRS)

Lee, Christopher A.

1994-01-01

This report describes the preliminary design of an Oblique All-Wing (OAW) supersonic transport and a corresponding wind-tunnel model that was tested in the NASA Ames 9- by 7-Foot supersonic wind tunnel. The main goal was the determination of the cruise performance (lift/drag ratio) of a realistically configured OAW. To achieve an acceptable level of realism, it was necessary to consider many issues of design practicality such as the need for a viable propulsion system, adequate control surfaces, landing gear, provisions for 450 passengers, and fuel to fly 5,000 nautical miles. The aircraft had to be stable, structurally sound, and needed to fit into airports across the world. Support was directed primarily towards integration of the propulsion system, however, there were notable contributions to many aspects of the configuration design, wind tunnel model, and wind tunnel test.

Screening mechanisms in hybrid metric-Palatini gravity

NASA Astrophysics Data System (ADS)

Santos, Marcelo Vargas dos; Alcaniz, Jailson S.; Mota, David F.; Capozziello, Salvatore

2018-05-01

We investigate the efficiency of screening mechanisms in the hybrid metric-Palatini gravity. The value of the field is computed around spherical bodies embedded in a background of constant density. We find a thin shell condition for the field depending on the background field value. To quantify how the thin shell effect is relevant, we analyze how it behaves in the neighborhood of different astrophysical objects (planets, moons, or stars). We find that the condition is very well satisfied except only for some peculiar objects. Furthermore we establish bounds on the model using data from Solar System experiments such as the spectral deviation measured by the Cassini mission and the stability of the Earth-Moon system, which gives the best constraint to date on f (R ) theories. These bounds contribute to fix the range of viable hybrid gravity models.

Instrumentation for optimizing an underground coal-gasification process

NASA Astrophysics Data System (ADS)

Seabaugh, W.; Zielinski, R. E.

1982-06-01

While the United States has a coal resource base of 6.4 trillion tons, only seven percent is presently recoverable by mining. The process of in-situ gasification can recover another twenty-eight percent of the vast resource, however, viable technology must be developed for effective in-situ recovery. The key to this technology is system that can optimize and control the process in real-time. An instrumentation system is described that optimizes the composition of the injection gas, controls the in-situ process and conditions the product gas for maximum utilization. The key elements of this system are Monsanto PRISM Systems, a real-time analytical system, and a real-time data acquisition and control system. This system provides from complete automation of the process but can easily be overridden by manual control. The use of this cost effective system can provide process optimization and is an effective element in developing a viable in-situ technology.

Agent-based simulation for human-induced hazard analysis.

PubMed

Bulleit, William M; Drewek, Matthew W

2011-02-01

Terrorism could be treated as a hazard for design purposes. For instance, the terrorist hazard could be analyzed in a manner similar to the way that seismic hazard is handled. No matter how terrorism is dealt with in the design of systems, the need for predictions of the frequency and magnitude of the hazard will be required. And, if the human-induced hazard is to be designed for in a manner analogous to natural hazards, then the predictions should be probabilistic in nature. The model described in this article is a prototype model that used agent-based modeling (ABM) to analyze terrorist attacks. The basic approach in this article of using ABM to model human-induced hazards has been preliminarily validated in the sense that the attack magnitudes seem to be power-law distributed and attacks occur mostly in regions where high levels of wealth pass through, such as transit routes and markets. The model developed in this study indicates that ABM is a viable approach to modeling socioeconomic-based infrastructure systems for engineering design to deal with human-induced hazards. © 2010 Society for Risk Analysis.

Crew appliance study

NASA Technical Reports Server (NTRS)

Proctor, B. W.; Reysa, R. P.; Russell, D. J.

1975-01-01

Viable crew appliance concepts were identified by means of a thorough literature search. Studies were made of the food management, personal hygiene, housekeeping, and off-duty habitability functions to determine which concepts best satisfy the Space Shuttle Orbiter and Modular Space Station mission requirements. Models of selected appliance concepts not currently included in the generalized environmental-thermal control and life support systems computer program were developed and validated. Development plans of selected concepts were generated for future reference. A shuttle freezer conceptual design was developed and a test support activity was provided for regenerative environmental control life support subsystems.

Solar energy system economic evaluation final report for SEMCO-Loxahatchee, Loxahatchee National Wildlife refuge, Palm Beach County, Florida

NASA Technical Reports Server (NTRS)

1980-01-01

Economic analysis of the solar energy system installed at Loxahatchee, was developed for Loxahatchee and four other sites typical of a wide range of environmental and economic conditions in the continental United States. This analysis was accomplished based on the technical and economic models in the f Chart design procedure with inputs based on the characteristics of the installed system and local conditions. The results are expressed in terms of the economic parameters of present worth of system costs over a projected twenty year life, life cycle savings, year of positive savings and year of payback for the optimized solar energy system at each of the analysis sites. The sensitivity of the economic evaluation to uncertainties in constituent system and economic variables was also investigated. The results demonstrate that the solar energy system is economically viable at all of the five sites for which the analysis was conducted.

A Performance Prediction Model for a Fault-Tolerant Computer During Recovery and Restoration. Ph.D. Thesis Report, 1 Jan. - 31 Dec. 1992

NASA Technical Reports Server (NTRS)

Stoughton, John W.; Obando, Rodrigo A.

1993-01-01

The modeling and design of a fault-tolerant multiprocessor system is addressed. In particular, the behavior of the system during recovery and restoration after a fault has occurred is investigated. Given that a multicomputer system is designed using the Algorithm to Architecture to Mapping Model (ATAMM), and that a fault (death of a computing resource) occurs during its normal steady-state operation, a model is presented as a viable research tool for predicting the performance bounds of the system during its recovery and restoration phases. Furthermore, the bounds of the performance behavior of the system during this transient mode can be assessed. These bounds include: time to recover from the fault (t(sub rec)), time to restore the system (t(sub rec)) and whether there is a permanent delay in the system's Time Between Input and Output (TBIO) after the system has reached a steady state. An implementation of an ATAMM based computer was developed with the Generic VHSIC Spaceborne Computer (GVSC) as the target system. A simulation of the GVSC was also written based on the code used in ATAMM Multicomputer Operating System (AMOS). The simulation is in turn used to validate the new model in the usefulness and accuracy in tracking the propagation of the delay through the system and predicting the behavior in the transient state of recovery and restoration. The model is validated as an accurate method to predict the transient behavior of an ATAMM based multicomputer during recovery and restoration.

The immunomodulatory properties of viable Lactobacillus salivarius ssp. salivarius CECT5713 are not restricted to the large intestine.

PubMed

Arribas, Belén; Garrido-Mesa, Natividad; Perán, Laura; Camuesco, Desirée; Comalada, Mònica; Bailón, Elvira; Olivares, Mónica; Xaus, Jordi; Kruidenier, Laurens; Sanderson, Ian R; Zarzuelo, Antonio; Rodríguez-Cabezas, Maria Elena; Gálvez, Julio

2012-04-01

The aim of this study was to better characterise the biological effects of Lactobacillus salivarius ssp. salivarius CECT5713, a probiotic with immunomodulatory properties. Live or dead probiotic was assayed in the TNBS model of rat colitis to determine whether viability was a requisite to exert the beneficial effects. In vitro studies were also performed in Caco-2 cells to evaluate its effects on epithelial cell recovery and IL-8 production. Finally, the probiotic was assayed in the LPS model of septic shock in mice to establish its effects when there is an altered systemic immune response. The viability of the probiotic was required for its anti-inflammatory activity. The probiotic inhibited IL-8 production in stimulated Caco-2 cells and facilitated the recovery of damaged intestinal epithelium. In LPS-treated mice, the probiotic inhibited the production of TNFα in plasma and lungs and increased the hepatic glutathione content. These effects were associated with an improvement in the altered production of the T-cell cytokines in splenocytes, by reducing IL-2 and IL-5 and by increasing IL-10. Finally, it reduced the increased plasma IgG production in LPS-treated mice. The anti-inflammatory effects of viable L. salivarius ssp. salivarius CECT5713 are not restricted to the gastrointestinal tract.

Entropic multi-relaxation free-energy lattice Boltzmann model for two-phase flows

NASA Astrophysics Data System (ADS)

Bösch, F.; Dorschner, B.; Karlin, I.

2018-04-01

The entropic multi-relaxation lattice Boltzmann method is extended to two-phase systems following the free-energy approach. Gain in stability is achieved by incorporating the force term due to Korteweg's stress into the redefined entropic stabilizer, which allows simulation of higher Weber and Reynolds numbers with an efficient and explicit algorithm. Results for head-on droplet collisions and droplet impact on super-hydrophobic substrates are matching experimental data accurately. Furthermore, it is demonstrated that the entropic stabilization leads to smaller spurious currents without affecting the interface thickness. The present findings demonstrate the universality of the simple and explicit entropic lattice Boltzmann models and provide a viable and robust alternative to existing methods.

An upward compatible spectrum sharing architecture for existing, actively planned and emerging mobile satellite systems

NASA Technical Reports Server (NTRS)

Azarbar, Bahman

1990-01-01

Existing and actively planned mobile satellite systems are competing for a viable share of the spectrum allocated by the International Telecommunications Union (ITU) to the satellite based mobile services in the 1.5/1.6 GHz range. The limited amount of spectrum available worldwide and the sheer number of existing and planned mobile satellite systems dictate the adoption of an architecture which will maximize sharing possibilities. A viable sharing architecture must recognize the operational needs and limitations of the existing systems. Furthermore, recognizing the right of access of the future systems as they will emerge in time, the adopted architecture must allow for additional growth and be amenable to orderly introduction of future systems. An attempt to devise such a sharing architecture is described. A specific example of the application of the basic concept to the existing and planned mobile satellite systems is also discussed.

Electric Drive Dynamic Thermal System Model for Advanced Vehicle Propulsion Technologies: Cooperative Research and Development Final Report, CRADA Number CRD-09-360

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennion, K.

Electric drive systems, which include electric machines and power electronics, are a key enabling technology for advanced vehicle propulsion systems that reduce the dependence of the U.S. transportation sector on petroleum. However, to penetrate the market, these electric drive technologies must enable vehicle solutions that are economically viable. The push to make critical electric drivesystems smaller, lighter, and more cost-effective brings respective challenges associated with heat removal and system efficiency. In addition, the wide application of electric drive systems to alternative propulsion technologies ranging from integrated starter generators, to hybrid electric vehicles, to full electric vehicles presents challenges in termsmore » of sizing critical components andthermal management systems over a range of in-use operating conditions. This effort focused on developing a modular modeling methodology to enable multi-scale and multi-physics simulation capabilities leading to generic electric drive system models applicable to alternative vehicle propulsion configurations. The primary benefit for the National Renewable Energy Laboratory (NREL) is the abilityto define operating losses with the respective impact on component sizing, temperature, and thermal management at the component, subsystem, and system level. However, the flexible nature of the model also allows other uses related to evaluating the impacts of alternative component designs or control schemes depending on the interests of other parties.« less

Overview of NASA Electrified Aircraft Propulsion Research for Large Subsonic Transports

NASA Technical Reports Server (NTRS)

Jansen, Ralph H.; Bowman, Cheryl; Jankovsky, Amy; Dyson, Rodger; Felder, James L.

2017-01-01

NASA is investing in Electrified Aircraft Propulsion (EAP) research as part of the portfolio to improve the fuel efficiency, emissions, and noise levels in commercial transport aircraft. Turboelectric, partially turboelectric, and hybrid electric propulsion systems are the primary EAP configurations being evaluated for regional jet and larger aircraft. The goal is to show that one or more viable EAP concepts exist for narrow body aircraft and mature tall-pole technologies related to those concepts. A summary of the aircraft system studies, technology development, and facility development is provided. The leading concept for mid-term (2035) introduction of EAP for a single aisle aircraft is a tube and wing, partially turbo electric configuration (STARC-ABL), however other viable configurations exist. Investments are being made to raise the TRL level of light weight, high efficiency motors, generators, and electrical power distribution systems as well as to define the optimal turbine and boundary layer ingestion systems for a mid-term tube and wing configuration. An electric aircraft power system test facility (NEAT) is under construction at NASA Glenn and an electric aircraft control system test facility (HEIST) is under construction at NASA Armstrong. The correct building blocks are in place to have a viable, large plane EAP configuration tested by 2025 leading to entry into service in 2035 if the community chooses to pursue that goal.

Factors affecting success of an integrated community-based telehealth system.

PubMed

Hsieh, Hui-Lung; Tsai, Chung-Hung; Chih, Wen-Hai; Lin, Huei-Hsieh

2015-01-01

The rise of chronic and degenerative diseases in developed countries has become one critical epidemiologic issue. Telehealth can provide one viable way to enhance health care, public health, and health education delivery and support. The study aims to empirically examine and evaluate the success factors of community-based telehealth system adoption. The valid 336 respondents are the residents of a rural community in Taiwan. The structural equation modeling (SEM) was used to assess the proposed model applied to telehealth. The findings showed the research model had good explanatory power and fitness. Also, the findings indicated that system quality exerted the strongest overall effect on intention to use. Furthermore, service quality exerted the strongest overall effect on user satisfaction. The findings also illustrated that the joint effects of three intrinsic qualities (system quality, information quality, and service quality) on use were mediated by user satisfaction and intention to use. The study implies that community-based telehealth service providers should improve three intrinsic qualities to enhance user satisfaction and intention to use, which in turn can lead to increase the usage of the telehealth equipment. The integrated community-based telehealth system may become an innovative and suitable way to deliver better care to the residents of communities.

Identifying viable regulatory and innovation pathways for regenerative medicine: a case study of cultured red blood cells.

PubMed

Mittra, J; Tait, J; Mastroeni, M; Turner, M L; Mountford, J C; Bruce, K

2015-01-25

The creation of red blood cells for the blood transfusion markets represents a highly innovative application of regenerative medicine with a medium term (5-10 year) prospect for first clinical studies. This article describes a case study analysis of a project to derive red blood cells from human embryonic stem cells, including the systemic challenges arising from (i) the selection of appropriate and viable regulatory protocols and (ii) technological constraints related to stem cell manufacture and scale up to clinical Good Manufacturing Practice (GMP) standard. The method used for case study analysis (Analysis of Life Science Innovation Systems (ALSIS)) is also innovative, demonstrating a new approach to social and natural science collaboration to foresight product development pathways. Issues arising along the development pathway include cell manufacture and scale-up challenges, affected by regulatory demands emerging from the innovation ecosystem (preclinical testing and clinical trials). Our discussion reflects on the efforts being made by regulators to adapt the current pharmaceuticals-based regulatory model to an allogeneic regenerative medicine product and the broader lessons from this case study for successful innovation and translation of regenerative medicine therapies, including the role of methodological and regulatory innovation in future development in the field. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Emerging biological roles for erythropoietin in the nervous system.

PubMed

Brines, Michael; Cerami, Anthony

2005-06-01

Erythropoietin mediates an evolutionarily conserved, ancient immune response that limits damage to the heart, the nervous system and other tissues following injury. New evidence indicates that erythropoietin specifically prevents the destruction of viable tissue surrounding the site of an injury by signalling through a non-haematopoietic receptor. Engineered derivatives of erythropoietin that have a high affinity for this receptor have been developed, and these show robust tissue-protective effects in diverse preclinical models without stimulating erythropoiesis. A recent successful proof-of-concept clinical trial that used erythropoietin to treat human patients who had suffered a stroke encourages the evaluation of both this cytokine and non-erythropoietic derivatives as therapeutic agents to limit tissue injury.

The financial viability of an SOFC cogeneration system in single-family dwellings

NASA Astrophysics Data System (ADS)

Alanne, Kari; Saari, Arto; Ugursal, V. Ismet; Good, Joel

In the near future, fuel cell-based residential micro-CHP systems will compete with traditional methods of energy supply. A micro-CHP system may be considered viable if its incremental capital cost compared to its competitors equals to cumulated savings during a given period of time. A simplified model is developed in this study to estimate the operation of a residential solid oxide fuel cell (SOFC) system. A comparative assessment of the SOFC system vis-à-vis heating systems based on gas, oil and electricity is conducted using the simplified model for a single-family house located in Ottawa and Vancouver. The energy consumption of the house is estimated using the HOT2000 building simulation program. A financial analysis is carried out to evaluate the sensitivity of the maximum allowable capital cost with respect to system sizing, acceptable payback period, energy price and the electricity buyback strategy of an energy utility. Based on the financial analysis, small (1-2 kW e) SOFC systems seem to be feasible in the considered case. The present study shows also that an SOFC system is especially an alternative to heating systems based on oil and electrical furnaces.

How Close We Are to Achieving Commercially Viable Large-Scale Photobiological Hydrogen Production by Cyanobacteria: A Review of the Biological Aspects

PubMed Central

Sakurai, Hidehiro; Masukawa, Hajime; Kitashima, Masaharu; Inoue, Kazuhito

2015-01-01

Photobiological production of H2 by cyanobacteria is considered to be an ideal source of renewable energy because the inputs, water and sunlight, are abundant. The products of photobiological systems are H2 and O2; the H2 can be used as the energy source of fuel cells, etc., which generate electricity at high efficiencies and minimal pollution, as the waste product is H2O. Overall, production of commercially viable algal fuels in any form, including biomass and biodiesel, is challenging, and the very few systems that are operational have yet to be evaluated. In this paper we will: briefly review some of the necessary conditions for economical production, summarize the reports of photobiological H2 production by cyanobacteria, present our schemes for future production, and discuss the necessity for further progress in the research needed to achieve commercially viable large-scale H2 production. PMID:25793279

Analysis of human tissue management models for medical research: preparation for implementation of the 2012 revision of the Bioethics and Safety Act of Korea.

PubMed

Ryu, Young-Joon; Kim, Hankyeom; Jang, Sejin; Koo, Young-Mo

2013-06-01

Efficient management of human tissue samples is a critical issue; the supply of samples is unable to satisfy the current demands for research. Lack of informed consent is also an ethical problem. One of the goals of the 2012 revision of Korea's Bioethics and Safety Act was to implement regulations that govern the management of human tissue samples. To remain competitive, medical institutions must prepare for these future changes. In this report, we review two tissue management models that are currently in use; model 1 is the most common system utilized by hospitals in Korea and model 2 is implemented by some of the larger institutions. We also propose three alternative models that offer advantages over the systems currently in use. Model 3 is a multi-bank model that protects the independence of physicians and pathologists. Model 4 utilizes a comprehensive single bioresource bank; although in this case, the pathologists gain control of the samples, which may make it difficult to implement. Model 5, which employs a bioresource utilization steering committee (BUSC), is viable to implement and still maintains the advantages of Model 4. To comply with the upcoming law, we suggest that physicians and pathologists in an institution should collaborate to choose one of the improved models of tissue management system that best fits for their situation.

Efficient transportation for Vermont : optimal statewide transit networks.

DOT National Transportation Integrated Search

2011-01-01

"Public transit systems are receiving increased attention as viable solutions to problems with : transportation system robustness, energy-efficiency and equity. The over-reliance on a single : mode, the automobile, is a threat to system robustness. I...

Necrosis targeted radiotherapy with iodine-131-labeled hypericin to improve anticancer efficacy of vascular disrupting treatment in rabbit VX2 tumor models.

PubMed

Shao, Haibo; Zhang, Jian; Sun, Ziping; Chen, Feng; Dai, Xu; Li, Yaming; Ni, Yicheng; Xu, Ke

2015-06-10

A viable rim of tumor cells surrounding central necrosis always exists and leads to tumor recurrence after vascular disrupting treatment (VDT). A novel necrosis targeted radiotherapy (NTRT) using iodine-131-labeled hypericin (131I-Hyp) was specifically designed to treat viable tumor rim and improve tumor control after VDT in rabbit models of multifocal VX2 tumors. NTRT was administered 24 hours after VDT. Tumor growth was significantly slowed down by NTRT with a smaller tumor volume and a prolonged tumor doubling time (14.4 vs. 5.7 days), as followed by in vivo magnetic resonance imaging over 12 days. The viable tumor rims were well inhibited in NTRT group compared with single VDT control group, as showed on tumor cross sections at day 12 (1 vs. 3.7 in area). High targetability of 131I-Hyp to tumor necrosis was demonstrated by in vivo SPECT as high uptake in tumor regions lasting over 9 days with 4.26 to 98 times higher radioactivity for necrosis versus the viable tumor and other organs by gamma counting, and with ratios of 7.7-11.7 and 10.5-13.7 for necrosis over peri-tumor tissue by autoradiography and fluorescence microscopy, respectively. In conclusion, NTRT improved the anticancer efficacy of VDT in rabbits with VX2 tumors.

Development of a Commercially Viable, Modular Autonomous Robotic Systems for Converting any Vehicle to Autonomous Control

NASA Technical Reports Server (NTRS)

Parish, David W.; Grabbe, Robert D.; Marzwell, Neville I.

1994-01-01

A Modular Autonomous Robotic System (MARS), consisting of a modular autonomous vehicle control system that can be retrofit on to any vehicle to convert it to autonomous control and support a modular payload for multiple applications is being developed. The MARS design is scalable, reconfigurable, and cost effective due to the use of modern open system architecture design methodologies, including serial control bus technology to simplify system wiring and enhance scalability. The design is augmented with modular, object oriented (C++) software implementing a hierarchy of five levels of control including teleoperated, continuous guidepath following, periodic guidepath following, absolute position autonomous navigation, and relative position autonomous navigation. The present effort is focused on producing a system that is commercially viable for routine autonomous patrolling of known, semistructured environments, like environmental monitoring of chemical and petroleum refineries, exterior physical security and surveillance, perimeter patrolling, and intrafacility transport applications.

Expression of adhesion molecules, chemokines and matrix metallo- proteinases (MMPs) in viable and degenerating stage of Taenia solium metacestode in swine neurocysticercosis.

PubMed

Singh, Satyendra K; Singh, Aloukick K; Prasad, Kashi N; Singh, Amrita; Singh, Avinash; Rai, Ravi P; Tripathi, Mukesh; Gupta, Rakesh K; Husain, Nuzhat

2015-11-30

Neurocysticercosis (NCC) is a parasitic infection of central nervous system (CNS). Expression of adhesion molecules, chemokines and matrix metalloproteinases (MMPs) were investigated on brain tissues surrounding viable (n=15) and degenerating cysticerci (n=15) of Taenia solium in swine by real-time RT-PCR and ELISA. Gelatin gel zymography was performed for MMPs activity. ICAM-1 (intercellular adhesion molecule-1), E-selectin, MIP-1α (macrophage inflammatory protein-1α), Eotaxin-1 and RANTES (regulated on activation, normal T cell expressed and secreted) were associated with degenerating cysticerci (cysts). However, VCAM-1 (vascular cell adhesion molecule-1), MCP-1 (monocyte chemotactic protein-1), MMP-2 and MMP-9 were associated with both viable and degenerating cysts. In conclusion, viable and degenerating cysticerci have different immune molecule profiles and role of these molecules in disease pathogenesis needs to be investigated. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid and Sensitive Enumeration of Viable Diluted Cells of Members of the Family Enterobacteriaceae in Freshwater and Drinking Water

PubMed Central

Baudart, Julia; Coallier, Josée; Laurent, Patrick; Prévost, Michèle

2002-01-01

Water quality assessment involves the specific, sensitive, and rapid detection of bacterial indicators and pathogens in water samples, including viable but nonculturable (VBNC) cells. This work evaluates the specificity and sensitivity of a new method which combines a fluorescent in situ hybridization (FISH) approach with a physiological assay (direct viable count [DVC]) for the direct enumeration, at the single-cell level, of highly diluted viable cells of members of the family Enterobacteriaceae in freshwater and drinking water after membrane filtration. The approach (DVC-FISH) uses a new direct detection device, the laser scanning cytometer (Scan RDI). Combining the DVC-FISH method on a membrane with Scan RDI detection makes it possible to detect as few as one targeted cell in approximately 108 nontargeted cells spread over the membrane. The ability of this new approach to detect and enumerate VBNC enterobacterial cells in freshwater and drinking water distribution systems was investigated and is discussed. PMID:12324357

Hypoxia induces arginase II expression and increases viable human pulmonary artery smooth muscle cell numbers via AMPKα1 signaling

PubMed Central

Xue, Jianjing; Nelin, Leif D.

2017-01-01

Pulmonary artery smooth muscle cell (PASMC) proliferation is one of the hallmark features of hypoxia-induced pulmonary hypertension. With only supportive treatment options available for this life-threatening disease, treating and preventing the proliferation of PASMCs is a viable therapeutic option. A key promoter of hypoxia-induced increases in the number of viable human PASMCs is arginase II, with attenuation of viable cell numbers following pharmacologic inhibition or siRNA knockdown of the enzyme. Additionally, increased levels of arginase have been demonstrated in the pulmonary vasculature of patients with pulmonary hypertension. The signaling pathways responsible for the hypoxic induction of arginase II in PASMCs, however, remain unknown. Hypoxia is a recognized activator of AMPK, which is known to be expressed in human PASMCs (hPASMCs). Activation of AMPK by hypoxia has been shown to promote cell survival in PASMCs. In addition, pharmacologic agents targeting AMPK have been shown to attenuate chronic hypoxia-induced pulmonary hypertension in animal models. The present studies tested the hypothesis that hypoxia-induced arginase II expression in hPASMCs is mediated through AMPK signaling. We found that pharmacologic inhibitors of AMPK, as well as siRNA knockdown of AMPKα1, prevented hypoxia-induced arginase II. The hypoxia-induced increase in viable hPASMC numbers was also prevented following both pharmacologic inhibition and siRNA knockdown of AMPK. Furthermore, we demonstrate that overexpression of AMPK induced arginase II protein expression and viable cells numbers in hPASMCs. PMID:28213467

The 60 GHz radiometric local vertical sensor experiment

NASA Technical Reports Server (NTRS)

Grauling, C. H., Jr.

1973-01-01

The experiment concept involves the use of millimeter wave radiation the atmospheric oxygen to provide vertical sensing information to a satellite-borne radiometer. The radiance profile studies require the calculation of ray brightness temperature as a function of tangential altitude and atmosphere model, and the computer program developed for this purpose is discussed. Detailed calculations have been made for a total of 12 atmosphere models, including some showing severe warning conditions. The experiment system analysis investigates the effect of various design choices on system behavior. Calculated temperature profiles are presented for a wide variety of frequencies, bandwidths, and atmosphere models. System performance is determined by the convolution of the brightness temperature and an assumed antenna pattern. A compensation scheme to account for different plateau temperatures is developed and demonstrated. The millimeter wave components developed for the local vertical sensor are discussed, with emphasis on the antenna, low noise mixer, and solid state local oscillator. It was concluded that a viable sensing technique exists, useful over a wide range of altitude with an accuracy generally on the order of 0.01 degree or better.

A bench-top hyperspectral imaging system to classify beef from Nellore cattle based on tenderness

NASA Astrophysics Data System (ADS)

Nubiato, Keni Eduardo Zanoni; Mazon, Madeline Rezende; Antonelo, Daniel Silva; Calkins, Chris R.; Naganathan, Govindarajan Konda; Subbiah, Jeyamkondan; da Luz e Silva, Saulo

2018-03-01

The aim of this study was to evaluate the accuracy of classification of Nellore beef aged for 0, 7, 14, or 21 days and classification based on tenderness and aging period using a bench-top hyperspectral imaging system. A hyperspectral imaging system (λ = 928-2524 nm) was used to collect hyperspectral images of the Longissimus thoracis et lumborum (aging n = 376 and tenderness n = 345) of Nellore cattle. The image processing steps included selection of region of interest, extraction of spectra, and indentification and evalution of selected wavelengths for classification. Six linear discriminant models were developed to classify samples based on tenderness and aging period. The model using the first derivative of partial absorbance spectra (give wavelength range spectra) was able to classify steaks based on the tenderness with an overall accuracy of 89.8%. The model using the first derivative of full absorbance spectra was able to classify steaks based on aging period with an overall accuracy of 84.8%. The results demonstrate that the HIS may be a viable technology for classifying beef based on tenderness and aging period.

Millimeter wave satellite concepts, volume 1

NASA Technical Reports Server (NTRS)

Hilsen, N. B.; Holland, L. D.; Thomas, R. E.; Wallace, R. W.; Gallagher, J. G.

1977-01-01

The identification of technologies necessary for development of millimeter spectrum communication satellites was examined from a system point of view. Development of methodology based on the technical requirements of potential services that might be assigned to millimeter wave bands for identifying the viable and appropriate technologies for future NASA millimeter research and development programs, and testing of this methodology with selected user applications and services were the goals of the program. The entire communications network, both ground and space subsystems was studied. Cost, weight, and performance models for the subsystems, conceptual design for point-to-point and broadcast communications satellites, and analytic relationships between subsystem parameters and an overall link performance are discussed along with baseline conceptual systems, sensitivity studies, model adjustment analyses, identification of critical technologies and their risks, and brief research and development program scenarios for the technologies judged to be moderate or extensive risks. Identification of technologies for millimeter satellite communication systems, and assessment of the relative risks of these technologies, was accomplished through subsystem modeling and link optimization for both point-to-point and broadcast applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Jacob; Edgar, Thomas W.; Daily, Jeffrey A.

With an ever-evolving power grid, concerns regarding how to maintain system stability, efficiency, and reliability remain constant because of increasing uncertainties and decreasing rotating inertia. To alleviate some of these concerns, demand response represents a viable solution and is virtually an untapped resource in the current power grid. This work describes a hierarchical control framework that allows coordination between distributed energy resources and demand response. This control framework is composed of two control layers: a coordination layer that ensures aggregations of resources are coordinated to achieve system objectives and a device layer that controls individual resources to assure the predeterminedmore » power profile is tracked in real time. Large-scale simulations are executed to study the hierarchical control, requiring advancements in simulation capabilities. Technical advancements necessary to investigate and answer control interaction questions, including the Framework for Network Co-Simulation platform and Arion modeling capability, are detailed. Insights into the interdependencies of controls across a complex system and how they must be tuned, as well as validation of the effectiveness of the proposed control framework, are yielded using a large-scale integrated transmission system model coupled with multiple distribution systems.« less

Optimization of PV/WIND/DIESEL Hybrid Power System in HOMER for Rural Electrification

NASA Astrophysics Data System (ADS)

Hassan, Q.; Jaszczur, M.; Abdulateef, J.

2016-09-01

A large proportion of the world's population lives in remote rural areas that are geographically isolated and sparsely populated. The present study is based on modeling, computer simulation and optimization of hybrid power generation system in the rural area in Muqdadiyah district of Diyala state, Iraq. Two renewable resources, namely, solar photovoltaic (PV) and wind turbine (WT) are considered. The HOMER software is used to study and design the proposed hybrid energy system model. Based on simulation results, it has been found that renewable energy sources perhaps replace the conventional energy sources and would be a feasible solution for the generation of electric power at remote locations with a reasonable investment. The hybrid power system solution to electrify the selected area resulted in a least-cost combination of the hybrid power system that can meet the demand in a dependable manner at a cost about (0.321/kWh). If the wind resources in the study area at the lower stage, it's not economically viable for a wind turbine to generate the electricity.

Is missing geographic positioning system data in accelerometry studies a problem, and is imputation the solution?

PubMed Central

Meseck, Kristin; Jankowska, Marta M.; Schipperijn, Jasper; Natarajan, Loki; Godbole, Suneeta; Carlson, Jordan; Takemoto, Michelle; Crist, Katie; Kerr, Jacqueline

2016-01-01

The main purpose of the present study was to assess the impact of global positioning system (GPS) signal lapse on physical activity analyses, discover any existing associations between missing GPS data and environmental and demographics attributes, and to determine whether imputation is an accurate and viable method for correcting GPS data loss. Accelerometer and GPS data of 782 participants from 8 studies were pooled to represent a range of lifestyles and interactions with the built environment. Periods of GPS signal lapse were identified and extracted. Generalised linear mixed models were run with the number of lapses and the length of lapses as outcomes. The signal lapses were imputed using a simple ruleset, and imputation was validated against person-worn camera imagery. A final generalised linear mixed model was used to identify the difference between the amount of GPS minutes pre- and post-imputation for the activity categories of sedentary, light, and moderate-to-vigorous physical activity. Over 17% of the dataset was comprised of GPS data lapses. No strong associations were found between increasing lapse length and number of lapses and the demographic and built environment variables. A significant difference was found between the pre- and post-imputation minutes for each activity category. No demographic or environmental bias was found for length or number of lapses, but imputation of GPS data may make a significant difference for inclusion of physical activity data that occurred during a lapse. Imputing GPS data lapses is a viable technique for returning spatial context to accelerometer data and improving the completeness of the dataset. PMID:27245796

Blood flow, flow reserve, and glucose utilization in viable and nonviable myocardium in patients with ischemic cardiomyopathy

PubMed Central

Zhang, Xiaoli; Schindler, Thomas H.; Prior, John O.; Sayre, James; Dahlbom, Magnus; Huang, Sung-Cheng

2016-01-01

Purpose The aim of the study was to determine whether glucose uptake in viable myocardium of ischemic cardiomyopathy patients depends on rest myocardial blood flow (MBF) and the residual myocardial flow reserve (MFR). Methods Thirty-six patients with ischemic cardiomyopathy (left ventricular ejection fraction 25±10 %) were studied with 13N-ammonia and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Twenty age-matched normals served as controls. Regional MBF was determined at rest and during dipyridamole hyperemia and regional FDG extraction was estimated from regional FDG to 13N-ammonia activity ratios. Results Rest MBF was reduced in viable (0.42±0.18 ml/min per g) and nonviable regions (0.32±0.09 ml/min per g) relative to remote regions (0.68±0.23 ml/min per g, p<0.001) and to normals (0.63±0.13 ml/min per g). Dipyridamole raised MBFs in controls, remote, viable, and nonviable regions. MBFs at rest (p<0.05) and stress (p<0.05) in viable regions were significantly higher than that in nonviable regions, while MFRs did not differ significantly (p>0.05). Compared to MFR in remote myocardium, MFRs in viable regions were similar (1.39±0.56 vs 1.70±0.45, p>0.05) but were significantly lower in nonviable regions (1.23±0.43, p<0.001). Moreover, the FDG and thus glucose extraction was higher in viable than in remote (1.40±0.14 vs 0.90±0.20, p<0.001) and in nonviable regions (1.13±0.21, p<0.001). The extraction of FDG in viable regions was independent of rest MBF but correlated inversely with MFRs (r=−0.424, p<0.05). No correlation between the FDG extraction and MFR was observed in nonviable regions. Conclusion As in the animal model, decreasing MFRs in viable myocardium are associated with increasing glucose extraction that likely reflects a metabolic adaptation of remodeling hibernating myocytes. PMID:23287994

Cosmological viability conditions for f(T) dark energy models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setare, M.R.; Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir

2012-11-01

Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch,more » then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.« less

Surface tension and modeling of cellular intercalation during zebrafish gastrulation.

PubMed

Calmelet, Colette; Sepich, Diane

2010-04-01

In this paper we discuss a model of zebrafish embryo notochord development based on the effect of surface tension of cells at the boundaries. We study the process of interaction of mesodermal cells at the boundaries due to adhesion and cortical tension, resulting in cellular intercalation. From in vivo experiments, we obtain cell outlines of time-lapse images of cell movements during zebrafish embryo development. Using Cellular Potts Model, we calculate the total surface energy of the system of cells at different time intervals at cell contacts. We analyze the variations of total energy depending on nature of cell contacts. We demonstrate that our model can be viable by calculating the total surface energy value for experimentally observed configurations of cells and showing that in our model these configurations correspond to a decrease in total energy values in both two and three dimensions.

Rewiring the severe acute respiratory syndrome coronavirus (SARS-CoV) transcription circuit: Engineering a recombination-resistant genome

NASA Astrophysics Data System (ADS)

Yount, Boyd; Roberts, Rhonda S.; Lindesmith, Lisa; Baric, Ralph S.

2006-08-01

Live virus vaccines provide significant protection against many detrimental human and animal diseases, but reversion to virulence by mutation and recombination has reduced appeal. Using severe acute respiratory syndrome coronavirus as a model, we engineered a different transcription regulatory circuit and isolated recombinant viruses. The transcription network allowed for efficient expression of the viral transcripts and proteins, and the recombinant viruses replicated to WT levels. Recombinant genomes were then constructed that contained mixtures of the WT and mutant regulatory circuits, reflecting recombinant viruses that might occur in nature. Although viable viruses could readily be isolated from WT and recombinant genomes containing homogeneous transcription circuits, chimeras that contained mixed regulatory networks were invariantly lethal, because viable chimeric viruses were not isolated. Mechanistically, mixed regulatory circuits promoted inefficient subgenomic transcription from inappropriate start sites, resulting in truncated ORFs and effectively minimize viral structural protein expression. Engineering regulatory transcription circuits of intercommunicating alleles successfully introduces genetic traps into a viral genome that are lethal in RNA recombinant progeny viruses. regulation | systems biology | vaccine design

The potential for harvesting "puckerbrush" for fuel.

Treesearch

James A. Mattson; Sharon A. Winsauer

1985-01-01

Documents the biomass in 12 typical stands of puckerbrush and evaluates the feasibility of several potential systems to harvest these stands. Identifies areas of needed development for economically viable harvesting systems.

Construction and potential application of controlled autolytic systems for Lactobacillus casei in cheese manufacture.

PubMed

Xu, Yi; Kong, Jian

2013-07-01

The rapid release of intracellular enzymes into the curd by the autolysis of lactic acid bacteria starters is universally recognized as a critical biological process to accelerate cheese ripening. Lactobacillus casei is typically the dominant nonstarter lactic acid bacterium in the ripening cheese. In this study, two controlled autolytic systems were established in L. casei BL23, based on the exploitation of the autolysins sourced from Lactococcus lactis (AcmA) and Enterococcus faecalis (AtlA). The lysis abilities of the systems were demonstrated both in broth and a model cheese, in which a fivefold increase in lactate dehydrogenase activity was detected in the curd with sufficient viable starter cells being maintained, indicating that they could lead to the timely release of intracellular enzymes.

Discourse Systems and Aspirin Bottles: On Literacy.

ERIC Educational Resources Information Center

Gee, James Paul

1988-01-01

Any use of language involves the following interlocking systems: (1) referential; (2) contextualization; and (3) ideology. These together constitute culturally viable "discourse systems." Examination of these systems as they operate in daily contexts reveals a paradox in the concept of literacy. (Author/BJV)

Space-based solar power conversion and delivery systems study. Volume 3: Economic analysis of space-based solar power systems

NASA Technical Reports Server (NTRS)

Hazelrigg, G. A., Jr.

1976-01-01

A variety of economic and programmatic issues are discussed concerning the development and deployment of a fleet of space-based solar power satellites (SSPS). The costs, uncertainties and risks associated with the current photovoltaic SSPS configuration, and with issues affecting the development of an economically viable SSPS development program are analyzed. The desirability of a low earth orbit (LEO) demonstration satellite and a geosynchronous (GEO) pilot satellite is examined and critical technology areas are identified. In addition, a preliminary examination of utility interface issues is reported. The main focus of the effort reported is the development of SSPS unit production, and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM). It is shown that the key technology area deals with the productivity of man in space, not, as might be expected, with some hardware component technology.

Magnetically levitated mesenchymal stem cell spheroids cultured with a collagen gel maintain phenotype and quiescence

PubMed Central

Lewis, Natasha S; Lewis, Emily EL; Mullin, Margaret; Wheadon, Helen; Dalby, Matthew J; Berry, Catherine C

2017-01-01

Multicellular spheroids are an established system for three-dimensional cell culture. Spheroids are typically generated using hanging drop or non-adherent culture; however, an emerging technique is to use magnetic levitation. Herein, mesenchymal stem cell spheroids were generated using magnetic nanoparticles and subsequently cultured within a type I collagen gel, with a view towards developing a bone marrow niche environment. Cells were loaded with magnetic nanoparticles, and suspended beneath an external magnet, inducing self-assembly of multicellular spheroids. Cells in spheroids were viable and compared to corresponding monolayer controls, maintained stem cell phenotype and were quiescent. Interestingly, core spheroid necrosis was not observed, even with increasing spheroid size, in contrast to other commonly used spheroid systems. This mesenchymal stem cell spheroid culture presents a potential platform for modelling in vitro bone marrow stem cell niches, elucidating interactions between cells, as well as a useful model for drug delivery studies. PMID:28616152

Analysis of Network Address Shuffling as a Moving Target Defense

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carroll, Thomas E.; Crouse, Michael B.; Fulp, Errin W.

2014-06-10

Address shuffling is a type of moving target defense that prevents an attacker from reliably contacting a system by periodically remapping network addresses. Although limited testing has demonstrated it to be effective, little research has been conducted to examine the theoretical limits of address shuffling. As a result, it is difficult to understand how effective shuffling is and under what circumstances it is a viable moving target defense. This paper introduces probabilistic models that can provide insight into the performance of address shuffling. These models quantify the probability of attacker success in terms of network size, quantity of addresses scanned,more » quantity of vulnerable systems, and the frequency of shuffling. Theoretical analysis will show that shuffling is an acceptable defense if there is a small population of vulnerable systems within a large network address space, however shuffling has a cost for legitimate users. These results will also be shown empirically using simulation and actual traffic traces.« less

A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

NASA Astrophysics Data System (ADS)

Brunetti, Giuseppe; Šimůnek, Jiří; Piro, Patrizia

2016-09-01

The increasing frequency of flooding events in urban catchments related to an increase in impervious surfaces highlights the inadequacy of traditional urban drainage systems. Low Impact Development (LID) techniques have proven to be a viable and effective alternative by reducing stormwater runoff and increasing the infiltration and evapotranspiration capacity of urban areas. However, the lack of adequate modeling tools represents a barrier in designing and constructing such systems. This paper investigates the suitability of a mechanistic model, HYDRUS-1D, to correctly describe the hydraulic behavior of permeable pavement installed at the University of Calabria. Two different scenarios of describing the hydraulic behavior of the permeable pavement system were analyzed: the first one uses a single-porosity model for all layers of the permeable pavement; the second one uses a dual-porosity model for the base and sub-base layers. Measured and modeled month-long hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index. A Global Sensitivity Analysis (GSA) followed by a Monte Carlo filtering highlighted the influence of the wear layer on the hydraulic behavior of the pavement and identified the ranges of parameters generating behavioral solutions. Reduced ranges were then used in the calibration procedure conducted with the metaheuristic Particle swarm optimization (PSO) algorithm for the estimation of hydraulic parameters. The best fit value for the first scenario was NSE = 0.43; for the second scenario, it was NSE = 0.81, indicating that the dual-porosity approach is more appropriate for describing the variably-saturated flow in the base and sub-base layers. Estimated parameters were validated using an independent, month-long set of measurements, resulting in NSE values of 0.43 and 0.86 for the first and second scenarios, respectively. The improvement in correspondence between measured and modeled hydrographs confirmed the reliability of the combination of GSA and PSO in dealing with highly dimensional optimization problems. Obtained results have demonstrated that PSO, due to its easiness of implementation and effectiveness, can represent a new and viable alternative to traditional optimization algorithms for the inverse estimation of unsaturated hydraulic properties. Finally, the results confirmed the suitability and the accuracy of HYDRUS-1D in correctly describing the hydraulic behavior of permeable pavements.

Testing a dual-fluorescence assay to monitor the viability of filamentous cyanobacteria.

PubMed

Johnson, Tylor J; Hildreth, Michael B; Gu, Liping; Zhou, Ruanbao; Gibbons, William R

2015-06-01

Filamentous cyanobacteria are currently being engineered to produce long-chain organic compounds, including 3rd generation biofuels. Because of their filamentous morphology, standard methods to quantify viability (e.g., plate counts) are not possible. This study investigated a dual-fluorescence assay based upon the LIVE/DEAD® BacLight™ Bacterial Viability Kit to quantify the percent viability of filamentous cyanobacteria using a microplate reader in a high throughput 96-well plate format. The manufacturer's protocol calls for an optical density normalization step to equalize the numbers of viable and non-viable cells used to generate calibration curves. Unfortunately, the isopropanol treatment used to generate non-viable cells released a blue pigment that altered absorbance readings of the non-viable cell solution, resulting in an inaccurate calibration curve. Thus we omitted this optical density normalization step, and carefully divided cell cultures into two equal fractions before the isopropanol treatment. While the resulting calibration curves had relatively high correlation coefficients, their use in various experiments resulted in viability estimates ranging from below 0% to far above 100%. We traced this to the apparent inaccuracy of the propidium iodide (PI) dye that was to stain only non-viable cells. Through further analysis via microplate reader, as well as confocal and wide-field epi-fluorescence microscopy, we observed non-specific binding of PI in viable filamentous cyanobacteria. While PI will not work for filamentous cyanobacteria, it is possible that other fluorochrome dyes could be used to selectively stain non-viable cells. This will be essential in future studies for screening mutants and optimizing photobioreactor system performance for filamentous cyanobacteria. Copyright © 2015 Elsevier B.V. All rights reserved.

Multisite evaluation of the BD™ Stem Cell Enumeration (SCE) Kit for CD34+ cell enumeration on the BD FACSCanto II™ and BD FACSCalibur™ flow cytometers

PubMed Central

Preti, Robert A; Chan, Wai Shun; Kurtzberg, Joanne; Dornsife, Ronna E.; Wallace, Paul K.; Furlange, Rosemary; Lin, Anna; Omana-Zapata, Imelda; Bonig, Halvard; Tonn, Thorsten

2018-01-01

Background Evaluation of the BD™ Stem Cell Enumeration (SCE) Kit was conducted at four clinical sites with flow cytometry CD34+ enumeration, to assess agreement between two investigational methods, the BD FACSCanto™ II and BD FACSCalibur™ systems, and the predicate method (Beckman Coulter Stem-Kit™ reagents). Methods Leftover and delinked specimens (n = 1,032) from clinical flow cytometry testing were analyzed on the BD FACSCanto II (n = 918) and BD FACSCalibur (n = 905) in normal and mobilized blood, frozen and thawed bone marrow, and leucopheresis and cord blood anticoagulated with CPD, ACD-A, heparin, and EDTA alone or in combination. Fresh leucopheresis analysis addressed site equivalency for sample preparation, testing, and analysis. Results The mean relative bias showed agreement within predefined parameters for the BD FACSCanto II (−2.81 to 4.31 ±7.1) and BD FACSCalibur (−2.69 to 5.2 ±7.9). Results are reported as absolute and relative differences compared to the predicate for viable CD34+, percentage of CD34+ in CD45+, and viable CD45+ populations (or gates). Bias analyses of the distribution of the predicate low, mid, and high bin values were done using BD FACSCanto II optimal gating and BD FACSCalibur manual gating for viable CD34+, percentage of CD34+ in CD45+, and viable CD45+. Bias results from both investigational methods show agreement. Deming regression analyses showed a linear relationship with R2 >0.92 for both investigational methods. Discussion In conclusion, the results from both investigational methods demonstrated agreement and equivalence with the predicate method for enumeration of absolute viable CD34+, percentage of viable CD34+ in CD45+, and absolute viable CD45+ populations. PMID:24927716

Filtering Meteoroid Flights Using Multiple Unscented Kalman Filters

NASA Astrophysics Data System (ADS)

Sansom, E. K.; Bland, P. A.; Rutten, M. G.; Paxman, J.; Towner, M. C.

2016-11-01

Estimator algorithms are immensely versatile and powerful tools that can be applied to any problem where a dynamic system can be modeled by a set of equations and where observations are available. A well designed estimator enables system states to be optimally predicted and errors to be rigorously quantified. Unscented Kalman filters (UKFs) and interactive multiple models can be found in methods from satellite tracking to self-driving cars. The luminous trajectory of the Bunburra Rockhole fireball was observed by the Desert Fireball Network in mid-2007. The recorded data set is used in this paper to examine the application of these two techniques as a viable approach to characterizing fireball dynamics. The nonlinear, single-body system of equations, used to model meteoroid entry through the atmosphere, is challenged by gross fragmentation events that may occur. The incorporation of the UKF within an interactive multiple model smoother provides a likely solution for when fragmentation events may occur as well as providing a statistical analysis of the state uncertainties. In addition to these benefits, another advantage of this approach is its automatability for use within an image processing pipeline to facilitate large fireball data analyses and meteorite recoveries.

Developing a cost effective rock bed thermal energy storage system: Design and modelling

NASA Astrophysics Data System (ADS)

Laubscher, Hendrik Frederik; von Backström, Theodor Willem; Dinter, Frank

2017-06-01

Thermal energy storage is an integral part of the drive for low cost of concentrated solar power (CSP). Storage of thermal energy enables CSP plants to provide base load power. Alternative, cheaper concepts for storing thermal energy have been conceptually proposed in previous studies. Using rocks as a storage medium and air as a heat transfer fluid, the proposed concept offers the potential of lower cost storage because of the abundance and affordability of rocks. A packed rock bed thermal energy storage (TES) concept is investigated and a design for an experimental rig is done. This paper describes the design and modelling of an experimental test facility for a cost effective packed rock bed thermal energy storage system. Cost effective, simplified designs for the different subsystems of an experimental setup are developed based on the availability of materials and equipment. Modelling of this design to predict the thermal performance of the TES system is covered in this study. If the concept under consideration proves to be successful, a design that is scalable and commercially viable can be proposed for further development of an industrial thermal energy storage system.

Air-Abrasive Disinfection of Implant Surfaces in a Simulated Model of Periimplantitis.

PubMed

Quintero, David George; Taylor, Robert Bonnie; Miller, Matthew Braden; Merchant, Keith Roshanali; Pasieta, Scott Anthony

2017-06-01

This in vitro study aimed to evaluate the ability of air-powder abrasion to decontaminate dental implants. Twenty-six implants were inoculated with a Streptococcus sanguinis biofilm media in a novel periimplantitis defect model. Six implants served as controls, and 20 implants were disinfected with either the Cavitron JET Plus or the AIR-FLOW PERIO air-powder abrasion units. Residual bacteria were cultured, and colony forming units (CFUs) were totaled at 24 hours. As expected, negative control implant cultures showed no evidence of viable bacteria. Bacterial growth was observed on all positive control cultures, whereas only 15% of the experimental cultures displayed evidence of viable bacteria. The average CFU per streak for the positive control was 104 compared with a maximum of 10 and 4 CFUs for the Cavitron JET Plus and AIR-FLOW PERIO, respectively. There was a 99.9% reduction in bacteria for both air-powder abrasion instruments. Air-powder abrasion is an effective technique for the decontamination of dental implants, and the Cavitron JET Plus and AIR-FLOW PERIO are equally successful at eliminating viable bacteria from implant surfaces.

Emerging governance approaches for tourism in the protected areas of china.

PubMed

Su, Dan; Wall, Geoffrey; Eagles, Paul F J

2007-06-01

This paper examines the recent evolution in the governance of protected area tourism in China. China now sees cooperation in the form of public-private partnerships occurring between authorized private tourism enterprises in various organizational forms and the public managers from specific portfolio departments of governments at different levels. Three types of governance models are visible: the Leasing Model, the Non-listed Share-holding Model, and the Public-listed Share-holding Model. Theories of corporate governance were applied to these models to analyze the internal and external mechanisms of supervision and incentives for both the government agencies and the authorized tourism enterprises for nature-based tourism operations. The Principal-Agent problem and the supervision mechanism are the focus of the analysis. The emerging governance approaches for tourism in protected areas of China are all theoretically viable, as explained by the theory of property rights and corporate governance, and practically viable as elaborated in the cases of the three types of governance models summarized in this paper.

A stochastic bioburden model for spacecraft sterilization.

NASA Technical Reports Server (NTRS)

Roark, A. L.

1972-01-01

Development of a stochastic model of the probability distribution for the random variable representing the number of microorganisms on a surface as a function of time. The first basic principle associated with bioburden estimation is that viable particles are removed from surfaces. The second notion important to the analysis is that microorganisms in environments and on surfaces occur in clumps. The last basic principle relating to bioburden modeling is that viable particles are deposited on a surface. The bioburden on a spacecraft is determined by the amount and kind of control exercised on the spacecraft assembly location, the shedding characteristics of the individuals in the vicinity of the spacecraft, its orientation, the geographical location in which the assembly takes place, and the steps in the assembly procedure. The model presented has many of the features which are desirable for its use in the spacecraft sterilization programs currently being planned by NASA.

Modeling rainfall-runoff process using soft computing techniques

NASA Astrophysics Data System (ADS)

Kisi, Ozgur; Shiri, Jalal; Tombul, Mustafa

2013-02-01

Rainfall-runoff process was modeled for a small catchment in Turkey, using 4 years (1987-1991) of measurements of independent variables of rainfall and runoff values. The models used in the study were Artificial Neural Networks (ANNs), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Gene Expression Programming (GEP) which are Artificial Intelligence (AI) approaches. The applied models were trained and tested using various combinations of the independent variables. The goodness of fit for the model was evaluated in terms of the coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), coefficient of efficiency (CE) and scatter index (SI). A comparison was also made between these models and traditional Multi Linear Regression (MLR) model. The study provides evidence that GEP (with RMSE=17.82 l/s, MAE=6.61 l/s, CE=0.72 and R2=0.978) is capable of modeling rainfall-runoff process and is a viable alternative to other applied artificial intelligence and MLR time-series methods.

Application of a hyaluronic acid gel after intrauterine surgery may improve spontaneous fertility: a randomized controlled trial in New Zealand White rabbits.

PubMed

Huberlant, Stephanie; Fernandez, Herve; Vieille, Pierre; Khrouf, Mohamed; Ulrich, Daniela; deTayrac, Renaud; Letouzey, Vincent

2015-01-01

Intrauterine adhesions (IUAs) are the most common complication after hysteroscopy in patients of reproductive age. Intra-abdominal anti-adhesion gel reduces the incidence of adhesions, but effects on fertility after uterine surgery are not known. The objective of our work was to evaluate the effect of intrauterine anti-adhesion gel on spontaneous fertility after repeated intrauterine surgery with induced experimental synechiae in the rabbit model. Twenty New Zealand White rabbits underwent a double uterine curettage 10 days apart and were randomized into two groups. Each rabbit served as its own control: one uterine tube was the treatment group (A), the second uterine tube was the control group (B) to avoid bias through other causes of infertility. Group A received a post curettage intrauterine instillation of anti-adhesion gel whereas group B, the control group, underwent curettage without instillation of the gel. After a recovery period, the rabbits were mated. An abdominal ultrasound performed 21 days after mating allowed us to diagnose pregnancy and quantify the number of viable fetuses. There was a significant difference in total fetuses in favor of group A, with an average of 3.7 (range, 0-9) total fetuses per tube against 2.1 (0-7) in group B (p = .04). The number of viable fetuses shows a trend in favor of group A, with an average of 3.4 (0-7) viable fetuses per tube against 1.9 (0-6) viable fetuses per tube in group B (p = .05). The use of immediate postoperative anti-adhesion gel improved fertility in an animal model after intrauterine surgery likely to cause uterine synechiae. This experimental model will permit comparison of different anti-adhesion solutions, including assessment of their tolerance and potential mucosal toxicity on embryonic development.

Thermal characterization of three-dimensional printed components for light-emitting diode lighting system applications

NASA Astrophysics Data System (ADS)

Perera, Indika U.; Narendran, Nadarajah; Terentyeva, Valeria

2018-04-01

This study investigated the thermal properties of three-dimensional (3-D) printed components with the potential to be used for thermal management in light-emitting diode (LED) applications. Commercially available filament materials with and without a metal filler were characterized with changes to the print orientation. 3-D printed components with an in-plane orientation had >30 % better effective thermal conductivity compared with components printed with a cross-plane orientation. A finite-element analysis was modeled to understand the effective thermal conductivity changes in the 3-D printed components. A simple thermal resistance model was used to estimate the required effective thermal conductivity of the 3-D printed components to be a viable alternative in LED thermal management applications.

Conformal piezoelectric energy harvesting and storage from motions of the heart, lung, and diaphragm

PubMed Central

Dagdeviren, Canan; Yang, Byung Duk; Su, Yewang; Tran, Phat L.; Joe, Pauline; Anderson, Eric; Xia, Jing; Doraiswamy, Vijay; Dehdashti, Behrooz; Feng, Xue; Lu, Bingwei; Poston, Robert; Khalpey, Zain; Ghaffari, Roozbeh; Huang, Yonggang; Slepian, Marvin J.; Rogers, John A.

2014-01-01

Here, we report advanced materials and devices that enable high-efficiency mechanical-to-electrical energy conversion from the natural contractile and relaxation motions of the heart, lung, and diaphragm, demonstrated in several different animal models, each of which has organs with sizes that approach human scales. A cointegrated collection of such energy-harvesting elements with rectifiers and microbatteries provides an entire flexible system, capable of viable integration with the beating heart via medical sutures and operation with efficiencies of ∼2%. Additional experiments, computational models, and results in multilayer configurations capture the key behaviors, illuminate essential design aspects, and offer sufficient power outputs for operation of pacemakers, with or without battery assist. PMID:24449853

Status of the scalar singlet dark matter model

NASA Astrophysics Data System (ADS)

Athron, Peter; Balázs, Csaba; Bringmann, Torsten; Buckley, Andy; Chrząszcz, Marcin; Conrad, Jan; Cornell, Jonathan M.; Dal, Lars A.; Edsjö, Joakim; Farmer, Ben; Jackson, Paul; Kahlhoefer, Felix; Krislock, Abram; Kvellestad, Anders; McKay, James; Mahmoudi, Farvah; Martinez, Gregory D.; Putze, Antje; Raklev, Are; Rogan, Christopher; Saavedra, Aldo; Savage, Christopher; Scott, Pat; Serra, Nicola; Weniger, Christoph; White, Martin

2017-08-01

One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a Z_2 symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. We include the dark matter relic density measured by Planck, direct searches with LUX, PandaX, SuperCDMS and XENON100, limits on invisible Higgs decays from the Large Hadron Collider, searches for high-energy neutrinos from dark matter annihilation in the Sun with IceCube, and searches for gamma rays from annihilation in dwarf galaxies with the Fermi-LAT. Viable solutions remain at couplings of order unity, for singlet masses between the Higgs mass and about 300 GeV, and at masses above ˜ 1 TeV. Only in the latter case can the scalar singlet constitute all of dark matter. Frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the Higgs, can also account for all of dark matter, and remains viable. However, Bayesian considerations show this region to be rather fine-tuned.

Author’s response: A universal approach to modeling visual word recognition and reading: not only possible, but also inevitable.

PubMed

Frost, Ram

2012-10-01

I have argued that orthographic processing cannot be understood and modeled without considering the manner in which orthographic structure represents phonological, semantic, and morphological information in a given writing system. A reading theory, therefore, must be a theory of the interaction of the reader with his/her linguistic environment. This outlines a novel approach to studying and modeling visual word recognition, an approach that focuses on the common cognitive principles involved in processing printed words across different writing systems. These claims were challenged by several commentaries that contested the merits of my general theoretical agenda, the relevance of the evolution of writing systems, and the plausibility of finding commonalities in reading across orthographies. Other commentaries extended the scope of the debate by bringing into the discussion additional perspectives. My response addresses all these issues. By considering the constraints of neurobiology on modeling reading, developmental data, and a large scope of cross-linguistic evidence, I argue that front-end implementations of orthographic processing that do not stem from a comprehensive theory of the complex information conveyed by writing systems do not present a viable approach for understanding reading. The common principles by which writing systems have evolved to represent orthographic, phonological, and semantic information in a language reveal the critical distributional characteristics of orthographic structure that govern reading behavior. Models of reading should thus be learning models, primarily constrained by cross-linguistic developmental evidence that describes how the statistical properties of writing systems shape the characteristics of orthographic processing. When this approach is adopted, a universal model of reading is possible.

Quasi-static evolution of coronal magnetic fields

NASA Technical Reports Server (NTRS)

Longcope, D. W.; Sudan, R. N.

1992-01-01

A formalism is developed to describe the purely quasi-static part of the evolution of a coronal loop driven by its footpoints. This is accomplished under assumptions of a long, thin loop. The quasi-static equations reveal the possibility for sudden 'loss of equilibrium' at which time the system evolves dynamically rather than quasi-statically. Such quasi-static crises produce high-frequency Alfven waves and, in conjunction with Alfven wave dissipation models, form a viable coronal heating mechanism. Furthermore, an approximate solution to the quasi-static equations by perturbation method verifies the development of small-scale spatial current structure.

Urban water infrastructure optimization to reduce environmental impacts and costs.

PubMed

Lim, Seong-Rin; Suh, Sangwon; Kim, Jung-Hoon; Park, Hung Suck

2010-01-01

Urban water planning and policy have been focusing on environmentally benign and economically viable water management. The objective of this study is to develop a mathematical model to integrate and optimize urban water infrastructures for supply-side planning and policy: freshwater resources and treated wastewater are allocated to various water demand categories in order to reduce contaminants in the influents supplied for drinking water, and to reduce consumption of the water resources imported from the regions beyond a city boundary. A case study is performed to validate the proposed model. An optimal urban water system of a metropolitan city is calculated on the basis of the model and compared to the existing water system. The integration and optimization decrease (i) average concentrations of the influents supplied for drinking water, which can improve human health and hygiene; (ii) total consumption of water resources, as well as electricity, reducing overall environmental impacts; (iii) life cycle cost; and (iv) water resource dependency on other regions, improving regional water security. This model contributes to sustainable urban water planning and policy. 2009 Elsevier Ltd. All rights reserved.

A break-even analysis of optimum faculty assignment for ambulatory primary care training.

PubMed

Xakellis, G C; Gjerde, C L; Xakellis, M G; Klitgaard, D

1996-12-01

The increased demand that faculty teach residents in ambulatory clinics necessitates the development of ambulatory care teaching models that are both educationally effective and financially viable. This study was designed to identify the resident-to-faculty ratios needed to provide financially viable faculty supervision of residents while maintaining acceptable resident waiting times for teaching. A computer simulation was developed to estimate the number of residents one or two faculty teachers could supervise in a university-based primary care teaching clinic. The number of residents was calculated for three waiting-time constraints and three scenarios of faculty tasks. A financial analysis of each model was performed. With no non-teaching tasks, two teachers were able to supervise 11 residents and keep waiting times under two minutes, while one teacher was able to supervise only three residents with this waiting-time constraint. The financial break-even point was achieved by all of the two-teacher models, but by none of the one-teacher models. In all three scenarios, using two teachers resulted in more than double the number of residents supervised and in higher utilization of faculty time (higher productivity) than did using one teacher. The two-teacher models of ambulatory supervision allowed for sufficient numbers of residents to be supervised so that teaching costs could be covered from patient care revenues; the one-teacher models did not break even financially. These simulations offer a viable option for academic institutions that are struggling to maintain teaching quality in the face of financial constraints.

Biological Potential in Serpentinizing Systems

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.

2016-01-01

Generation of the microbial substrate hydrogen during serpentinization, the aqueous alteration of ultramafic rocks, has focused interest on the potential of serpentinizing systems to support biological communities or even the origin of life. However the process also generates considerable alkalinity, a challenge to life, and both pH and hydrogen concentrations vary widely across natural systems as a result of different host rock and fluid composition and differing physical and hydrogeologic conditions. Biological potential is expected to vary in concert. We examined the impact of such variability on the bioenergetics of an example metabolism, methanogenesis, using a cell-scale reactive transport model to compare rates of metabolic energy generation as a function of physicochemical environment. Potential rates vary over more than 5 orders of magnitude, including bioenergetically non-viable conditions, across the range of naturally occurring conditions. In parallel, we assayed rates of hydrogen metabolism in wells associated with the actively serpentinizing Coast Range Ophiolite, which includes conditions more alkaline and considerably less reducing than is typical of serpentinizing systems. Hydrogen metabolism is observed at pH approaching 12 but, consistent with the model predictions, biological methanogenesis is not observed.

Advanced cathode materials for polymer electrolyte fuel cells based on pt/ metal oxides: from model electrodes to catalyst systems.

PubMed

Fabbri, Emiliana; Pătru, Alexandra; Rabis, Annett; Kötz, Rüdiger; Schmidt, Thomas J

2014-01-01

The development of stable catalyst systems for application at the cathode side of polymer electrolyte fuel cells (PEFCs) requires the substitution of the state-of-the-art carbon supports with materials showing high corrosion resistance in a strongly oxidizing environment. Metal oxides in their highest oxidation state can represent viable support materials for the next generation PEFC cathodes. In the present work a multilevel approach has been adopted to investigate the kinetics and the activity of Pt nanoparticles supported on SnO2-based metal oxides. Particularly, model electrodes made of SnO2 thin films supporting Pt nanoparticles, and porous catalyst systems made of Pt nanoparticles supported on Sb-doped SnO2 high surface area powders have been investigated. The present results indicate that SnO2-based supports do not modify the oxygen reduction reaction mechanism on the Pt nanoparticle surface, but rather lead to catalysts with enhanced specific activity compared to Pt/carbon systems. Different reasons for the enhancement in the specific activity are considered and discussed.

Analysis of energy efficient highway lighting retrofits.

DOT National Transportation Integrated Search

2015-06-01

Solid state lighting technology is advancing rapidly to a point where light emitting diode (LED) lighting : systems can be viable replacements for existing lighting systems using high pressure sodium (HPS). The : present report summarizes analyses co...

Navigation-aid power systems

NASA Technical Reports Server (NTRS)

Goltz, G. L.; Kaiser, L. M.; Weiner, H.

1979-01-01

Design synthesis and performance analysis (DSPA) program package is collection of subroutines used for computation of design and performance characteristics of viable solar-array-charged battery powered system for flashing-lamp buoys employed as maritime aids to navigation.

Review of NASA short-haul studies

NASA Technical Reports Server (NTRS)

Kenyon, G. C.

1975-01-01

The paper summarizes the results of NASA-conducted technological and economic studies of low, medium, and high density short-haul transportation systems. Aircraft concepts considered included CTOL, RTOL, STOL, and general aviation aircraft. For low density systems, it was found that viable air service becomes possible if city pairs are at least 100 km apart and a two-way total travel demand of at least 200 daily passengers exists. Currently available aircraft were found suitable. The medium-density study showed that a 60-passenger twin engine turbofan was the best suited aircraft. For high density systems, STOL appears to be an economically viable means of reducing noise and congestion at major hub airports. Adequate runways 914 m in length or greater either already exist or could be added to most existing major hub airports.

Automation life-cycle cost model

NASA Technical Reports Server (NTRS)

Gathmann, Thomas P.; Reeves, Arlinda J.; Cline, Rick; Henrion, Max; Ruokangas, Corinne

1992-01-01

The problem domain being addressed by this contractual effort can be summarized by the following list: Automation and Robotics (A&R) technologies appear to be viable alternatives to current, manual operations; Life-cycle cost models are typically judged with suspicion due to implicit assumptions and little associated documentation; and Uncertainty is a reality for increasingly complex problems and few models explicitly account for its affect on the solution space. The objectives for this effort range from the near-term (1-2 years) to far-term (3-5 years). In the near-term, the envisioned capabilities of the modeling tool are annotated. In addition, a framework is defined and developed in the Decision Modelling System (DEMOS) environment. Our approach is summarized as follows: Assess desirable capabilities (structure into near- and far-term); Identify useful existing models/data; Identify parameters for utility analysis; Define tool framework; Encode scenario thread for model validation; and Provide transition path for tool development. This report contains all relevant, technical progress made on this contractual effort.

A physiologically based mathematical model of dermal absorption in man.

PubMed

Auton, T R; Westhead, D R; Woollen, B H; Scott, R C; Wilks, M F

1994-01-01

A sound understanding of the mechanisms determining percutaneous absorption is necessary for toxicological risk assessment of chemicals contacting the skin. As part of a programme investigating these mechanisms we have developed a physiologically based mathematical model. The structure of the model parallels the multi-layer structure of the skin, with separate surface, stratum corneum and viable tissue layers. It simulates the effects of partitioning and diffusive transport between the sub-layers, and metabolism in the viable epidermis. In addition the model describes removal processes on the surface of the skin, including the effects of washing and desquamation, and rubbing off onto clothing. This model is applied to data on the penetration of the herbicide fluazifop-butyl through human skin in vivo and in vitro. Part of this dataset is used to estimate unknown model parameter values and the remainder is used to provide a partial validation of the model. Only a small fraction of the applied dose was absorbed through the skin; most of it was removed by washing or onto clothing. The model provides a quantitative description of these loss processes on the skin surface.

Failure Diagnosis for the Holdup Tank System via ISFA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Huijuan; Bragg-Sitton, Shannon; Smidts, Carol

This paper discusses the use of the integrated system failure analysis (ISFA) technique for fault diagnosis for the holdup tank system. ISFA is a simulation-based, qualitative and integrated approach used to study fault propagation in systems containing both hardware and software subsystems. The holdup tank system consists of a tank containing a fluid whose level is controlled by an inlet valve and an outlet valve. We introduce the component and functional models of the system, quantify the main parameters and simulate possible failure-propagation paths based on the fault propagation approach, ISFA. The results show that most component failures in themore » holdup tank system can be identified clearly and that ISFA is viable as a technique for fault diagnosis. Since ISFA is a qualitative technique that can be used in the very early stages of system design, this case study provides indications that it can be used early to study design aspects that relate to robustness and fault tolerance.« less

Why Are There so Many Different Models of Light?

ERIC Educational Resources Information Center

Robertson, William C.

2008-01-01

Is light a ray, a wave, or a particle? Yes, yes, and yes. An article in this issue ("The Benefits of Scientific Modeling," p. 40) discusses the process of scientific modeling, and light is a great example of how modeling works. There are three viable models for light, each appropriate for different situations. The author will discuss the…

The oxytocin system in drug discovery for autism: Animal models and novel therapeutic strategies

PubMed Central

Modi, Meera E.; Young, Larry J.

2012-01-01

Animal models and behavioral paradigms are critical for elucidating the neural mechanism involved in complex behaviors, including social cognition. Both genotype and phenotype based models have implicated the neuropeptide oxytocin (OT) in the regulation of social behavior. Based on the findings in animal models, alteration of the OT system has been hypothesized to play a role in the social deficits associated with autism and other neuropsychiatric disorders. While the evidence linking the peptide to the etiology of the disorder is not yet conclusive, evidence from multiple animal models suggest modulation of the OT system may be a viable strategy for the pharmacological treatment of social deficits. In this review, we will discuss how animal models have been utilized to understand the role of OT in social cognition and how those findings can be applied to the conceptualization and treatment of the social impairments in ASD. Animal models with genetic alterations of the OT system, like the OT, OT receptor and CD38 knock-out mice, and those with phenotypic variation in social behavior, like BTBR inbred mice and prairie voles, coupled with behavioral paradigms with face and construct validity may prove to have predictive validity for identifying the most efficacious methods of stimulating the OT system to enhance social cognition in humans. The widespread use of strong animal models of social cognition has the potential yield pharmacological, interventions for the treatment social impairments psychiatric disorders. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior. PMID:22206823

Solar system and equivalence principle constraints on f(R) gravity by the chameleon approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capozziello, Salvatore; Tsujikawa, Shinji

2008-05-15

We study constraints on f(R) dark energy models from solar system experiments combined with experiments on the violation of the equivalence principle. When the mass of an equivalent scalar field degree of freedom is heavy in a region with high density, a spherically symmetric body has a thin shell so that an effective coupling of the fifth force is suppressed through a chameleon mechanism. We place experimental bounds on the cosmologically viable models recently proposed in the literature that have an asymptotic form f(R)=R-{lambda}R{sub c}[1-(R{sub c}/R){sup 2n}] in the regime R>>R{sub c}. From the solar system constraints on the post-Newtonianmore » parameter {gamma}, we derive the bound n>0.5, whereas the constraints from the violations of the weak and strong equivalence principles give the bound n>0.9. This allows a possibility to find the deviation from the {lambda}-cold dark matter ({lambda}CDM) cosmological model. For the model f(R)=R-{lambda}R{sub c}(R/R{sub c}){sup p} with 0

An Overview of GIS-Based Modeling and Assessment of Mining-Induced Hazards: Soil, Water, and Forest

PubMed Central

Kim, Sung-Min; Yi, Huiuk; Choi, Yosoon

2017-01-01

In this study, current geographic information system (GIS)-based methods and their application for the modeling and assessment of mining-induced hazards were reviewed. Various types of mining-induced hazard, including soil contamination, soil erosion, water pollution, and deforestation were considered in the discussion of the strength and role of GIS as a viable problem-solving tool in relation to mining-induced hazards. The various types of mining-induced hazard were classified into two or three subtopics according to the steps involved in the reclamation procedure, or elements of the hazard of interest. Because GIS is appropriated for the handling of geospatial data in relation to mining-induced hazards, the application and feasibility of exploiting GIS-based modeling and assessment of mining-induced hazards within the mining industry could be expanded further. PMID:29186922

Beyond δ: Tailoring marked statistics to reveal modified gravity

NASA Astrophysics Data System (ADS)

Valogiannis, Georgios; Bean, Rachel

2018-01-01

Models which attempt to explain the accelerated expansion of the universe through large-scale modifications to General Relativity (GR), must satisfy the stringent experimental constraints of GR in the solar system. Viable candidates invoke a “screening” mechanism, that dynamically suppresses deviations in high density environments, making their overall detection challenging even for ambitious future large-scale structure surveys. We present methods to efficiently simulate the non-linear properties of such theories, and consider how a series of statistics that reweight the density field to accentuate deviations from GR can be applied to enhance the overall signal-to-noise ratio in differentiating the models from GR. Our results demonstrate that the cosmic density field can yield additional, invaluable cosmological information, beyond the simple density power spectrum, that will enable surveys to more confidently discriminate between modified gravity models and ΛCDM.

An Overview of GIS-Based Modeling and Assessment of Mining-Induced Hazards: Soil, Water, and Forest.

PubMed

Suh, Jangwon; Kim, Sung-Min; Yi, Huiuk; Choi, Yosoon

2017-11-27

In this study, current geographic information system (GIS)-based methods and their application for the modeling and assessment of mining-induced hazards were reviewed. Various types of mining-induced hazard, including soil contamination, soil erosion, water pollution, and deforestation were considered in the discussion of the strength and role of GIS as a viable problem-solving tool in relation to mining-induced hazards. The various types of mining-induced hazard were classified into two or three subtopics according to the steps involved in the reclamation procedure, or elements of the hazard of interest. Because GIS is appropriated for the handling of geospatial data in relation to mining-induced hazards, the application and feasibility of exploiting GIS-based modeling and assessment of mining-induced hazards within the mining industry could be expanded further.

GAMES II Project: a general architecture for medical knowledge-based systems.

PubMed

Bruno, F; Kindler, H; Leaning, M; Moustakis, V; Scherrer, J R; Schreiber, G; Stefanelli, M

1994-10-01

GAMES II aims at developing a comprehensive and commercially viable methodology to avoid problems ordinarily occurring in KBS development. GAMES II methodology proposes to design a KBS starting from an epistemological model of medical reasoning (the Select and Test Model). The design is viewed as a process of adding symbol level information to the epistemological model. The architectural framework provided by GAMES II integrates the use of different formalisms and techniques providing a large set of tools. The user can select the most suitable one for representing a piece of knowledge after a careful analysis of its epistemological characteristics. Special attention is devoted to the tools dealing with knowledge acquisition (both manual and automatic). A panel of practicing physicians are assessing the medical value of such a framework and its related tools by using it in a practical application.

Real time viability detection of bacterial spores

DOEpatents

Vanderberg, Laura A.; Herdendorf, Timothy J.; Obiso, Richard J.

2003-07-29

This invention relates to a process for detecting the presence of viable bacterial spores in a sample and to a spore detection system, the process including placing a sample in a germination medium for a period of time sufficient for commitment of any present viable bacterial spores to occur, mixing the sample with a solution of a lanthanide capable of forming a fluorescent complex with dipicolinic acid, and, measuring the sample for the presence of dipicolinic acid, and the system including a germination chamber having inlets from a sample chamber, a germinant chamber and a bleach chamber, the germination chamber further including an outlet through a filtering means, the outlet connected to a detection chamber, the detection chamber having an inlet from a fluorescence promoting metal chamber and the detection chamber including a spectral excitation source and a means of measuring emission spectra from a sample, the detection chamber further connected to a waste chamber. A germination reaction mixture useful for promoting commitment of any viable bacterial spores in a sample including a combination of L-alanine, L-asparagine and D-glucose is also described.

Architecture for Survivable System Processing (ASSP)

NASA Astrophysics Data System (ADS)

Wood, Richard J.

1991-11-01

The Architecture for Survivable System Processing (ASSP) Program is a multi-phase effort to implement Department of Defense (DOD) and commercially developed high-tech hardware, software, and architectures for reliable space avionics and ground based systems. System configuration options provide processing capabilities to address Time Dependent Processing (TDP), Object Dependent Processing (ODP), and Mission Dependent Processing (MDP) requirements through Open System Architecture (OSA) alternatives that allow for the enhancement, incorporation, and capitalization of a broad range of development assets. High technology developments in hardware, software, and networking models, address technology challenges of long processor life times, fault tolerance, reliability, throughput, memories, radiation hardening, size, weight, power (SWAP) and security. Hardware and software design, development, and implementation focus on the interconnectivity/interoperability of an open system architecture and is being developed to apply new technology into practical OSA components. To insure for widely acceptable architecture capable of interfacing with various commercial and military components, this program provides for regular interactions with standardization working groups (e.g.) the International Standards Organization (ISO), American National Standards Institute (ANSI), Society of Automotive Engineers (SAE), and Institute of Electrical and Electronic Engineers (IEEE). Selection of a viable open architecture is based on the widely accepted standards that implement the ISO/OSI Reference Model.

Architecture for Survivable System Processing (ASSP)

NASA Technical Reports Server (NTRS)

Wood, Richard J.

1991-01-01

The Architecture for Survivable System Processing (ASSP) Program is a multi-phase effort to implement Department of Defense (DOD) and commercially developed high-tech hardware, software, and architectures for reliable space avionics and ground based systems. System configuration options provide processing capabilities to address Time Dependent Processing (TDP), Object Dependent Processing (ODP), and Mission Dependent Processing (MDP) requirements through Open System Architecture (OSA) alternatives that allow for the enhancement, incorporation, and capitalization of a broad range of development assets. High technology developments in hardware, software, and networking models, address technology challenges of long processor life times, fault tolerance, reliability, throughput, memories, radiation hardening, size, weight, power (SWAP) and security. Hardware and software design, development, and implementation focus on the interconnectivity/interoperability of an open system architecture and is being developed to apply new technology into practical OSA components. To insure for widely acceptable architecture capable of interfacing with various commercial and military components, this program provides for regular interactions with standardization working groups (e.g.) the International Standards Organization (ISO), American National Standards Institute (ANSI), Society of Automotive Engineers (SAE), and Institute of Electrical and Electronic Engineers (IEEE). Selection of a viable open architecture is based on the widely accepted standards that implement the ISO/OSI Reference Model.

Power Management Based Current Control Technique for Photovoltaic-Battery Assisted Wind-Hydro Hybrid System

NASA Astrophysics Data System (ADS)

Ram Prabhakar, J.; Ragavan, K.

2013-07-01

This article proposes new power management based current control strategy for integrated wind-solar-hydro system equipped with battery storage mechanism. In this control technique, an indirect estimation of load current is done, through energy balance model, DC-link voltage control and droop control. This system features simpler energy management strategy and necessitates few power electronic converters, thereby minimizing the cost of the system. The generation-demand (G-D) management diagram is formulated based on the stochastic weather conditions and demand, which would likely moderate the gap between both. The features of management strategy deploying energy balance model include (1) regulating DC-link voltage within specified tolerances, (2) isolated operation without relying on external electric power transmission network, (3) indirect current control of hydro turbine driven induction generator and (4) seamless transition between grid-connected and off-grid operation modes. Furthermore, structuring of the hybrid system with appropriate selection of control variables enables power sharing among each energy conversion systems and battery storage mechanism. By addressing these intricacies, it is viable to regulate the frequency and voltage of the remote network at load end. The performance of the proposed composite scheme is demonstrated through time-domain simulation in MATLAB/Simulink environment.

Load Frequency Control of a Two-Area Thermal-Hybrid Power System Using a Novel Quasi-Opposition Harmony Search Algorithm

NASA Astrophysics Data System (ADS)

Mahto, Tarkeshwar; Mukherjee, V.

2016-09-01

In the present work, a two-area thermal-hybrid interconnected power system, consisting of a thermal unit in one area and a hybrid wind-diesel unit in other area is considered. Capacitive energy storage (CES) and CES with static synchronous series compensator (SSSC) are connected to the studied two-area model to compensate for varying load demand, intermittent output power and area frequency oscillation. A novel quasi-opposition harmony search (QOHS) algorithm is proposed and applied to tune the various tunable parameters of the studied power system model. Simulation study reveals that inclusion of CES unit in both the areas yields superb damping performance for frequency and tie-line power deviation. From the simulation results it is further revealed that inclusion of SSSC is not viable from both technical as well as economical point of view as no considerable improvement in transient performance is noted with its inclusion in the tie-line of the studied power system model. The results presented in this paper demonstrate the potential of the proposed QOHS algorithm and show its effectiveness and robustness for solving frequency and power drift problems of the studied power systems. Binary coded genetic algorithm is taken for sake of comparison.

Nuclear Cryogenic Propulsion Stage Affordable Development Strategy

NASA Technical Reports Server (NTRS)

Doughty, Glen E.; Gerrish, H. P.; Kenny, R. J.

2014-01-01

The development of nuclear power for space use in nuclear thermal propulsion (NTP) systems will involve significant expenditures of funds and require major technology development efforts. The development effort must be economically viable yet sufficient to validate the systems designed. Efforts are underway within the National Aeronautics and Space Administration's (NASA) Nuclear Cryogenic Propulsion Stage Project (NCPS) to study what a viable program would entail. The study will produce an integrated schedule, cost estimate and technology development plan. This will include the evaluation of various options for test facilities, types of testing and use of the engine, components, and technology developed. A "Human Rating" approach will also be developed and factored into the schedule, budget and technology development approach.

Fermion masses and mixings and dark matter constraints in a model with radiative seesaw mechanism

NASA Astrophysics Data System (ADS)

Bernal, Nicolás; Cárcamo Hernández, A. E.; de Medeiros Varzielas, Ivo; Kovalenko, Sergey

2018-05-01

We formulate a predictive model of fermion masses and mixings based on a Δ(27) family symmetry. In the quark sector the model leads to the viable mixing inspired texture where the Cabibbo angle comes from the down quark sector and the other angles come from both up and down quark sectors. In the lepton sector the model generates a predictive structure for charged leptons and, after radiative seesaw, an effective neutrino mass matrix with only one real and one complex parameter. We carry out a detailed analysis of the predictions in the lepton sector, where the model is only viable for inverted neutrino mass hierarchy, predicting a strict correlation between θ 23 and θ 13. We show a benchmark point that leads to the best-fit values of θ 12, θ 13, predicting a specific sin2 θ 23 ≃ 0.51 (within the 3 σ range), a leptonic CP-violating Dirac phase δ ≃ 281.6° and for neutrinoless double-beta decay m ee ≃ 41.3 meV. We turn then to an analysis of the dark matter candidates in the model, which are stabilized by an unbroken ℤ2 symmetry. We discuss the possibility of scalar dark matter, which can generate the observed abundance through the Higgs portal by the standard WIMP mechanism. An interesting possibility arises if the lightest heavy Majorana neutrino is the lightest ℤ2-odd particle. The model can produce a viable fermionic dark matter candidate, but only as a feebly interacting massive particle (FIMP), with the smallness of the coupling to the visible sector protected by a symmetry and directly related to the smallness of the light neutrino masses.

PMA-PhyloChip DNA Microarray to Elucidate Viable Microbial Community Structure

NASA Technical Reports Server (NTRS)

Venkateswaran, Kasthuri J.; Stam, Christina N.; Andersen, Gary L.; DeSantis, Todd

2011-01-01

Since the Viking missions in the mid-1970s, traditional culture-based methods have been used for microbial enumeration by various NASA programs. Viable microbes are of particular concern for spacecraft cleanliness, for forward contamination of extraterrestrial bodies (proliferation of microbes), and for crew health/safety (viable pathogenic microbes). However, a "true" estimation of viable microbial population and differentiation from their dead cells using the most sensitive molecular methods is a challenge, because of the stability of DNA from dead cells. The goal of this research is to evaluate a rapid and sensitive microbial detection concept that will selectively estimate viable microbes. Nucleic acid amplification approaches such as the polymerase chain reaction (PCR) have shown promise for reducing time to detection for a wide range of applications. The proposed method is based on the use of a fluorescent DNA intercalating agent, propidium monoazide (PMA), which can only penetrate the membrane of dead cells. The PMA-quenched reaction mixtures can be screened, where only the DNA from live cells will be available for subsequent PCR reaction and microarray detection, and be identified as part of the viable microbial community. An additional advantage of the proposed rapid method is that it will detect viable microbes and differentiate from dead cells in only a few hours, as opposed to less comprehensive culture-based assays, which take days to complete. This novel combination approach is called the PMA-Microarray method. DNA intercalating agents such as PMA have previously been used to selectively distinguish between viable and dead bacterial cells. Once in the cell, the dye intercalates with the DNA and, upon photolysis under visible light, produces stable DNA adducts. DNA cross-linked in this way is unavailable for PCR. Environmental samples suspected of containing a mixture of live and dead microbial cells/spores will be treated with PMA, and then incubated in the dark. Thereafter, the sample is exposed to visible light for five minutes, so that the DNA from dead cells will be cross-linked. Following this PMA treatment step, the sample is concentrated by centrifugation and washed (to remove excessive PMA) before DNA is extracted. The 16S rRNA gene fragments will be amplified by PCR to screen the total microbial community using PhyloChip DNA microarray analysis. This approach will detect only the viable microbial community since the PMA intercalated DNA from dead cells would be unavailable for PCR amplification. The total detection time including PCR reaction for low biomass samples will be a few hours. Numerous markets may use this technology. The food industry uses spore detection to validate new alternative food processing technologies, sterility, and quality. Pharmaceutical and medical equipment companies also detect spores as a marker for sterility. This system can be used for validating sterilization processes, water treatment systems, and in various public health and homeland security applications.

9978 AND 9975 TYPE B PACKAGING INTERNAL DATA COLLECTION FEASIBILITY TESTING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fogle, R.

The objective of this report is to document the findings from a series of proof-of-concept tests performed by Savannah River National Laboratory (SRNL) R and D Engineering, for the DOE Packaging Certification Program to determine if a viable radio link could be established from within the stainless steel confines of several drum-style DOE certified Type B radioactive materials packagings. Two in-hand, off-the-shelf radio systems were tested. The first system was a Wi-Fi Librestream Onsight{trademark} camera with a Fortress ES820 Access Point and the second was the On-Ramp Wireless Ultra-Link Processing{trademark} (ULP) radio system. These radio systems were tested within themore » Model 9975 and 9978 Type B packagings at the SRNL. This report documents the test methods and results. A path forward will also be recommended.« less

Alternative model for administration and analysis of research-based assessments

NASA Astrophysics Data System (ADS)

Wilcox, Bethany R.; Zwickl, Benjamin M.; Hobbs, Robert D.; Aiken, John M.; Welch, Nathan M.; Lewandowski, H. J.

2016-06-01

Research-based assessments represent a valuable tool for both instructors and researchers interested in improving undergraduate physics education. However, the historical model for disseminating and propagating conceptual and attitudinal assessments developed by the physics education research (PER) community has not resulted in widespread adoption of these assessments within the broader community of physics instructors. Within this historical model, assessment developers create high quality, validated assessments, make them available for a wide range of instructors to use, and provide minimal (if any) support to assist with administration or analysis of the results. Here, we present and discuss an alternative model for assessment dissemination, which is characterized by centralized data collection and analysis. This model provides a greater degree of support for both researchers and instructors in order to more explicitly support adoption of research-based assessments. Specifically, we describe our experiences developing a centralized, automated system for an attitudinal assessment we previously created to examine students' epistemologies and expectations about experimental physics. This system provides a proof of concept that we use to discuss the advantages associated with centralized administration and data collection for research-based assessments in PER. We also discuss the challenges that we encountered while developing, maintaining, and automating this system. Ultimately, we argue that centralized administration and data collection for standardized assessments is a viable and potentially advantageous alternative to the default model characterized by decentralized administration and analysis. Moreover, with the help of online administration and automation, this model can support the long-term sustainability of centralized assessment systems.

Blood flow, flow reserve, and glucose utilization in viable and nonviable myocardium in patients with ischemic cardiomyopathy.

PubMed

Zhang, Xiaoli; Schindler, Thomas H; Prior, John O; Sayre, James; Dahlbom, Magnus; Huang, Sung-Cheng; Schelbert, Heinrich R

2013-04-01

The aim of the study was to determine whether glucose uptake in viable myocardium of ischemic cardiomyopathy patients depends on rest myocardial blood flow (MBF) and the residual myocardial flow reserve (MFR). Thirty-six patients with ischemic cardiomyopathy (left ventricular ejection fraction 25 ± 10 %) were studied with (13)N-ammonia and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Twenty age-matched normals served as controls. Regional MBF was determined at rest and during dipyridamole hyperemia and regional FDG extraction was estimated from regional FDG to (13)N-ammonia activity ratios. Rest MBF was reduced in viable (0.42 ± 0.18 ml/min per g) and nonviable regions (0.32 ± 0.09 ml/min per g) relative to remote regions (0.68 ± 0.23 ml/min per g, p < 0.001) and to normals (0.63 ± 0.13 ml/min per g). Dipyridamole raised MBFs in controls, remote, viable, and nonviable regions. MBFs at rest (p < 0.05) and stress (p < 0.05) in viable regions were significantly higher than that in nonviable regions, while MFRs did not differ significantly (p > 0.05). Compared to MFR in remote myocardium, MFRs in viable regions were similar (1.39 ± 0.56 vs 1.70 ± 0.45, p > 0.05) but were significantly lower in nonviable regions (1.23 ± 0.43, p < 0.001). Moreover, the FDG and thus glucose extraction was higher in viable than in remote (1.40 ± 0.14 vs 0.90 ± 0.20, p < 0.001) and in nonviable regions (1.13 ± 0.21, p < 0.001). The extraction of FDG in viable regions was independent of rest MBF but correlated inversely with MFRs (r =-0.424, p < 0.05). No correlation between the FDG extraction and MFR was observed in nonviable regions. As in the animal model, decreasing MFRs in viable myocardium are associated with increasing glucose extraction that likely reflects a metabolic adaptation of remodeling hibernating myocytes.

Dynamics and Control of a Quadrotor with Active Geometric Morphing

NASA Astrophysics Data System (ADS)

Wallace, Dustin A.

Quadrotors are manufactured in a wide variety of shapes, sizes, and performance levels to fulfill a multitude of roles. Robodub Inc. has patented a morphing quadrotor which will allow active reconfiguration between various shapes for performance optimization across a wider spectrum of roles. The dynamics of the system are studied and modeled using Newtonian Mechanics. Controls are developed and simulated using both Linear Quadratic and Numerical Nonlinear Optimal control for a symmetric simplificiation of the system dynamics. Various unique vehicle capabilities are investigated, including novel single-throttle flight control using symmetric geometric morphing, as well as recovery from motor loss by reconfiguring into a trirotor configuration. The system dynamics were found to be complex and highly nonlinear. All attempted control strategies resulted in controllability, suggesting further research into each may lead to multiple viable control strategies for a physical prototype.

The rapid formation of functional monolayers on silicon under mild conditions.

PubMed

Ciampi, Simone; Luais, Erwann; James, Michael; Choudhury, Moinul H; Darwish, Nadim A; Gooding, J Justin

2014-05-07

We report on an exceedingly mild chemical functionalization of hydrogen-terminated Si(100) with unactivated and unprotected bifunctional α,ω-dialkynes. Monolayer formation occurs rapidly in the dark, and at room temperature, from dilute solutions of an aromatic-conjugated acetylene. The method addresses the poor reactivity of p-type substrates under mild conditions. We suggest the importance of several factors, including an optimal orientation for electron transfer between the adsorbate and the Si surface, conjugation of the acetylenic function with a π-system, as well as the choice of a solvent system that favors electron transfer and screens Coulombic interactions between surface holes and electrons. The passivated Si(100) electrode is amenable to further functionalization and shown to be a viable model system for redox studies at non-oxide semiconductor electrodes in aqueous solutions.

Wi-Fi real time location systems

NASA Astrophysics Data System (ADS)

Doll, Benjamin A.

This thesis objective was to determine the viability of utilizing an untrained Wi-Fi. real time location system as a GPS alternative for indoor environments. Background. research showed that GPS is rarely able to penetrate buildings to provide reliable. location data. The benefit of having location information in a facility and how they might. be used for disaster or emergency relief personnel and their resources motivated this. research. A building was selected with a well-deployed Wi-Fi infrastructure and its. untrained location feature was used to determine the distance between the specified. test points and the system identified location. It was found that the average distance. from the test point throughout the facility was 14.3 feet 80% of the time. This fell within. the defined viable range and supported that an untrained Wi-Fi RTLS system could be a. viable solution for GPS's lack of availability indoors.

NASA helicopter transmission system technology program

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.

1983-01-01

The purpose of the NASA Helicopter Transmission System Technology Program is to improve specific mechanical components and the technology for combining these into advanced drive systems to make helicopters more viable and cost competitive for commerical applications. The history, goals, and elements of the program are discussed.

76 FR 66758 - Remedies for Small Copyright Claims

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-27

... legal system hinders or prevents copyright owners from pursuing copyright infringement claims that have... helpful and viable. A. Challenges of the Current Legal System Currently, copyright owners interested in... Office is interested in learning about alternatives to the current legal system that might help alleviate...

Wireless global positioning system fleet tracking system at the University at Albany.

DOT National Transportation Integrated Search

2014-07-01

This report provides an overview of the project undertaken at the University at Albany to make alternative transportation a more : viable option by implementing a GPS Tracking System on the University bus fleet and broadcasting the bus locations to c...

Remedial action assessment system: Decision support for environmental cleanup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pennock, K.A.; Bohn, S.; Franklin, A.L.

1991-11-01

A large number of hazardous waste sites across the United States await treatment. Waste sites can be physically complex entities composed of multiple, possibly interacting contaminants distributed throughout one or more media. The sites may be active as well with contaminants escaping through one or more potential escape paths. Treatment of these sites requires a long and costly commitment involving the coordination of activities among several waste treatment professionals. In order to reduce the cost and time required for the specification of treatment at these waste sites. The Remedial Action Assessment System (RAAS) was proposed. RAAS is an automated informationmore » management system which utilizes a combination of expert reasoning and numerical models to produce the combinations of treatment technologies, known as treatment trains, which satisfy the treatment objectives of a particular site. In addition, RAAS supports the analysis of these trains with regard to effectiveness and cost so that the viable treatment trains can be measured against each other. The Remedial Action Assessment System is a hybrid system designed and constructed using object-oriented tools and techniques. RAAS is advertised as a hybrid system because it combines, in integral fashion, numerical computing (primarily quantitative models) with expert system reasoning. An object-oriented approach was selected due to many of its inherent advantages, among these the naturalness of modeling physical objects and processes.« less

Simple model of epidemics with pathogen mutation.

PubMed

Girvan, Michelle; Callaway, Duncan S; Newman, M E J; Strogatz, Steven H

2002-03-01

We study how the interplay between the memory immune response and pathogen mutation affects epidemic dynamics in two related models. The first explicitly models pathogen mutation and individual memory immune responses, with contacted individuals becoming infected only if they are exposed to strains that are significantly different from other strains in their memory repertoire. The second model is a reduction of the first to a system of difference equations. In this case, individuals spend a fixed amount of time in a generalized immune class. In both models, we observe four fundamentally different types of behavior, depending on parameters: (1) pathogen extinction due to lack of contact between individuals; (2) endemic infection; (3) periodic epidemic outbreaks; and (4) one or more outbreaks followed by extinction of the epidemic due to extremely low minima in the oscillations. We analyze both models to determine the location of each transition. Our main result is that pathogens in highly connected populations must mutate rapidly in order to remain viable.

A robust quantitative near infrared modeling approach for blend monitoring.

PubMed

Mohan, Shikhar; Momose, Wataru; Katz, Jeffrey M; Hossain, Md Nayeem; Velez, Natasha; Drennen, James K; Anderson, Carl A

2018-01-30

This study demonstrates a material sparing Near-Infrared modeling approach for powder blend monitoring. In this new approach, gram scale powder mixtures are subjected to compression loads to simulate the effect of scale using an Instron universal testing system. Models prepared by the new method development approach (small-scale method) and by a traditional method development (blender-scale method) were compared by simultaneously monitoring a 1kg batch size blend run. Both models demonstrated similar model performance. The small-scale method strategy significantly reduces the total resources expended to develop Near-Infrared calibration models for on-line blend monitoring. Further, this development approach does not require the actual equipment (i.e., blender) to which the method will be applied, only a similar optical interface. Thus, a robust on-line blend monitoring method can be fully developed before any large-scale blending experiment is viable, allowing the blend method to be used during scale-up and blend development trials. Copyright © 2017. Published by Elsevier B.V.

System learning approach to assess sustainability and ...

EPA Pesticide Factsheets

This paper presents a methodology that combines the power of an Artificial Neural Network and Information Theory to forecast variables describing the condition of a regional system. The novelty and strength of this approach is in the application of Fisher information, a key method in Information Theory, to preserve trends in the historical data and prevent over fitting projections. The methodology was applied to demographic, environmental, food and energy consumption, and agricultural production in the San Luis Basin regional system in Colorado, U.S.A. These variables are important for tracking conditions in human and natural systems. However, available data are often so far out of date that they limit the ability to manage these systems. Results indicate that the approaches developed provide viable tools for forecasting outcomes with the aim of assisting management toward sustainable trends. This methodology is also applicable for modeling different scenarios in other dynamic systems. Indicators are indispensable for tracking conditions in human and natural systems, however, available data is sometimes far out of date and limit the ability to gauge system status. Techniques like regression and simulation are not sufficient because system characteristics have to be modeled ensuring over simplification of complex dynamics. This work presents a methodology combining the power of an Artificial Neural Network and Information Theory to capture patterns in a real dyna

Multiresolution modeling with a JMASS-JWARS HLA Federation

NASA Astrophysics Data System (ADS)

Prince, John D.; Painter, Ron D.; Pendell, Brian; Richert, Walt; Wolcott, Christopher

2002-07-01

CACI, Inc.-Federal has built, tested, and demonstrated the use of a JMASS-JWARS HLA Federation that supports multi- resolution modeling of a weapon system and its subsystems in a JMASS engineering and engagement model environment, while providing a realistic JWARS theater campaign-level synthetic battle space and operational context to assess the weapon system's value added and deployment/employment supportability in a multi-day, combined force-on-force scenario. Traditionally, acquisition analyses require a hierarchical suite of simulation models to address engineering, engagement, mission and theater/campaign measures of performance, measures of effectiveness and measures of merit. Configuring and running this suite of simulations and transferring the appropriate data between each model is both time consuming and error prone. The ideal solution would be a single simulation with the requisite resolution and fidelity to perform all four levels of acquisition analysis. However, current computer hardware technologies cannot deliver the runtime performance necessary to support the resulting extremely large simulation. One viable alternative is to integrate the current hierarchical suite of simulation models using the DoD's High Level Architecture in order to support multi- resolution modeling. An HLA integration eliminates the extremely large model problem, provides a well-defined and manageable mixed resolution simulation and minimizes VV&A issues.

Integrating Surface Modeling into the Engineering Design Graphics Curriculum

ERIC Educational Resources Information Center

Hartman, Nathan W.

2006-01-01

It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

Unscreening Modified Gravity in the Matter Power Spectrum.

PubMed

Lombriser, Lucas; Simpson, Fergus; Mead, Alexander

2015-06-26

Viable modifications of gravity that may produce cosmic acceleration need to be screened in high-density regions such as the Solar System, where general relativity is well tested. Screening mechanisms also prevent strong anomalies in the large-scale structure and limit the constraints that can be inferred on these gravity models from cosmology. We find that by suppressing the contribution of the screened high-density regions in the matter power spectrum, allowing a greater contribution of unscreened low densities, modified gravity models can be more readily discriminated from the concordance cosmology. Moreover, by variation of density thresholds, degeneracies with other effects may be dealt with more adequately. Specializing to chameleon gravity as a worked example for screening in modified gravity, employing N-body simulations of f(R) models and the halo model of chameleon theories, we demonstrate the effectiveness of this method. We find that a percent-level measurement of the clipped power at k<0.3h/Mpc can yield constraints on chameleon models that are more stringent than what is inferred from Solar System tests or distance indicators in unscreened dwarf galaxies. Finally, we verify that our method is also applicable to the Vainshtein mechanism.

The Runaway Crisis: Is Family Therapy the Answer?

ERIC Educational Resources Information Center

Ostensen, Kay Wickett

1981-01-01

Presents research on the relationship of two family counseling models (one with temporary foster placement, one without) to the recidivism of runaway teenagers. Research shows the Brief Family Intervention counseling model to be a statistically viable tool in deterring repeated runaway episodes. (Author)

Quantitative assessment of viable cells of Lactobacillus plantarum strains in single, dual and multi-strain biofilms.

PubMed

Fernández Ramírez, Mónica D; Kostopoulos, Ioannis; Smid, Eddy J; Nierop Groot, Masja N; Abee, Tjakko

2017-03-06

Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential source of contamination. Copyright © 2016 Elsevier B.V. All rights reserved.

Dual system to reinforce biological containment of recombinant bacteria designed for rhizoremediation.

PubMed

Ronchel, M C; Ramos, J L

2001-06-01

Active biological containment (ABC) systems have been designed to control at will the survival or death of a bacterial population. These systems are based on the use of a killing gene, e.g., a porin-inducing protein such as the one encoded by the Escherichia coli gef gene, and a regulatory circuit that controls expression of the killing gene in response to the presence or absence of environmental signals. An ABC system for recombinant microorganisms that degrade a model pollutant was designed on the basis of the Pseudomonas putida TOL plasmid meta-cleavage regulatory circuit. The system consists of a fusion of the Pm promoter to lacI, whose expression is controlled by XylS with 3-methylbenzoate, and a fusion of a synthetic P(lac) promoter to gef. In the presence of the model pollutant, bacterial cells survived and degraded the target compound, whereas in the absence of the aromatic carboxylic acid cell death was induced. The system had two main drawbacks: (i) the slow death of the bacterial cells in soil versus the fast killing rate in liquid cultures in laboratory assays, and (ii) the appearance of mutants, at a rate of about 10(-8) per cell and generation, that did not die after the pollutant had been exhausted. We reinforced the ABC system by including it in a Deltaasd P. putida background. A P. putida Deltaasd mutant is viable only in complex medium supplemented with diaminopimelic acid, methionine, lysine, and threonine. We constructed a P. putida Deltaasd strain, called MCR7, with a Pm::asd fusion in the host chromosome. This strain was viable in the presence of 3-methylbenzoate because synthesis of the essential metabolites was achieved through XylS-dependent induction. In the P. putida MCR7 strain, an ABC system (Pm::lacI, xylS, P(lac)::gef) was incorporated into the host chromosome to yield strain MCR8. The number of MCR8 mutants that escaped killing was below our detection limit (<10(-9) mutants per cell and generation). The MCR8 strain survived and colonized rhizosphere soil with 3-methylbenzoate at a level similar to that of the wild-type strain. However, it disappeared in less than 20 to 25 days in soils without the pollutant, whereas an asd(+), biologically contained counterpart such as P. putida CMC4 was still detectable in soils after 100 days.

Clinical Application of Stem Cells in the Cardiovascular System

NASA Astrophysics Data System (ADS)

Stamm, Christof; Klose, Kristin; Choi, Yeong-Hoon

Regenerative medicine encompasses "tissue engineering" - the in vitro fabrication of tissues and/or organs using scaffold material and viable cells - and "cell therapy" - the transplantation or manipulation of cells in diseased tissue in vivo. In the cardiovascular system, tissue engineering strategies are being pursued for the development of viable replacement blood vessels, heart valves, patch material, cardiac pacemakers and contractile myocardium. Anecdotal clinical applications of such vessels, valves and patches have been described, but information on systematic studies of the performance of such implants is not available, yet. Cell therapy for cardiovascular regeneration, however, has been performed in large series of patients, and numerous clinical studies have produced sometimes conflicting results. The purpose of this chapter is to summarize the clinical experience with cell therapy for diseases of the cardiovascular system, and to analyse possible factors that may influence its outcome.

Localisation of threat substances in urban society - LOTUS: a viable tool for finding illegal bomb factories in cities

NASA Astrophysics Data System (ADS)

Önnerud, Hans; Wallin, Sara; Östmark, Henric; Menning, Dennis; Ek, Stefan; Ellis, Hanna; Kölhed, Malin

2011-06-01

Results of dispersion experiments and dispersion modelling of explosives, drugs, and their precursors will be presented. The dispersion of chemicals evolving during preparation of home made explosives and a drug produced in an improvised manner in an ordinary kitchen has been measured. Experiments with concentration of hydrogen peroxide have been performed during spring and summer of 2009 and 2010 and further experiments with concentration of hydrogen peroxide, synthesis and drying of TATP and Methamphetamine are planned for the spring and summer of 2011. Results from the experiments are compared to dispersion modelling to achieve a better understanding of the dispersion processes and the resulting substances and amounts available for detection outside the kitchen at distances of 10-30 m and longer. Typical concentration levels have been determined as a function of environmental conditions. The experiments and modelling are made as a part of the LOTUS project aimed at detecting and locating the illicit production of explosives and drugs in an urban environment. It can be concluded that the proposed LOTUS system concept, using mobile automatic sensors, data transfer, location via GSM/GPS for on-line detection of illicit production of explosive or precursors to explosives and drugs is a viable approach and is in accordance with historical and today's illicit bomb manufacturing. The overall objective and approach of the LOTUS project will also be presented together with two more projects called PREVAIL and EMPHASIS both aiming at hindering or finding illicit production of home made explosives.

Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

PubMed Central

Sabatier, Rodolphe; Doyen, Luc; Tichit, Muriel

2012-01-01

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations. PMID:22496746

VR closure rates for two vocational models.

PubMed

Fraser, Virginia V; Jones, Amanda M; Frounfelker, Rochelle; Harding, Brian; Hardin, Teresa; Bond, Gary R

2008-01-01

The Individual Placement and Support (IPS) model of supported employment is an evidence-based practice for individuals with psychiatric disabilities. To be financially viable, IPS programs require funding from the state-federal vocational rehabilitation (VR) system. However, some observers have questioned the compatibility of IPS and the VR system. Using a randomized controlled trial comparing IPS to a well-established vocational program called the Diversified Placement Approach (DPA), we examined rates of VR sponsorship and successful VR closures. We also describe the establishment of an active collaboration between a psychiatric rehabilitation agency and the state VR system to facilitate rapid VR sponsorship for IPS clients. Both IPS and DPA achieved a 44% rate of VR Status 26 closure when considering all clients entering the study. IPS and DPA averaged similar amount of time to achieve VR sponsorship. Time from vocational program entry to Status 26 was 51 days longer on average for IPS. Even though several IPS principles seem to run counter to VR practices, such as zero exclusion and rapid job search, we found IPS closure rates comparable to those for DPA, a vocational model that screens for readiness, provides prevocational preparation, and extensively uses agency-run businesses.

Extinction risk and structure of a food web model

NASA Astrophysics Data System (ADS)

Pękalski, Andrzej; Szwabiński, Janusz; Bena, Ioana; Droz, Michel

2008-03-01

We investigate in detail the model of a trophic web proposed by Amaral and Meyer [Phys. Rev. Lett. 82, 652 (1999)]. We focus on small-size systems that are relevant for real biological food webs and for which the fluctuations play an important role. We show, using Monte Carlo simulations, that such webs can be nonviable, leading to extinction of all species in small and/or weakly coupled systems. Estimations of the extinction times and survival chances are also given. We show that before the extinction the fraction of highly connected species (“omnivores”) is increasing. Viable food webs exhibit a pyramidal structure, where the density of occupied niches is higher at lower trophic levels, and moreover the occupations of adjacent levels are closely correlated. We also demonstrate that the distribution of the lengths of food chains has an exponential character and changes weakly with the parameters of the model. On the contrary, the distribution of avalanche sizes of the extinct species depends strongly on the connectedness of the web. For rather loosely connected systems, we recover the power-law type of behavior with the same exponent as found in earlier studies, while for densely connected webs the distribution is not of a power-law type.

An analysis of cross-coupling of a multicomponent jet engine test stand using finite element modeling techniques

NASA Technical Reports Server (NTRS)

Schweikhard, W. G.; Singnoi, W. N.

1985-01-01

A two axis thrust measuring system was analyzed by using a finite a element computer program to determine the sensitivities of the thrust vectoring nozzle system to misalignment of the load cells and applied loads, and the stiffness of the structural members. Three models were evaluated: (1) the basic measuring element and its internal calibration load cells; (2) the basic measuring element and its external load calibration equipment; and (3) the basic measuring element, external calibration load frame and the altitude facility support structure. Alignment of calibration loads was the greatest source of error for multiaxis thrust measuring systems. Uniform increases or decreases in stiffness of the members, which might be caused by the selection of the materials, have little effect on the accuracy of the measurements. It is found that the POLO-FINITE program is a viable tool for designing and analyzing multiaxis thrust measurement systems. The response of the test stand to step inputs that might be encountered with thrust vectoring tests was determined. The dynamic analysis show a potential problem for measuring the dynamic response characteristics of thrust vectoring systems because of the inherently light damping of the test stand.

Cosmology and accelerator tests of strongly interacting dark matter

DOE PAGES

Berlin, Asher; Blinov, Nikita; Gori, Stefania; ...

2018-03-23

A natural possibility for dark matter is that it is composed of the stable pions of a QCD-like hidden sector. Existing literature largely assumes that pion self-interactions alone control the early universe cosmology. We point out that processes involving vector mesons typically dominate the physics of dark matter freeze-out and significantly widen the viable mass range for these models. The vector mesons also give rise to striking signals at accelerators. For example, in most of the cosmologically favored parameter space, the vector mesons are naturally long-lived and produce standard model particles in their decays. Electron and proton beam fixed-target experimentsmore » such as HPS, SeaQuest, and LDMX can exploit these signals to explore much of the viable parameter space. As a result, we also comment on dark matter decay inherent in a large class of previously considered models and explain how to ensure dark matter stability.« less

Viable twin cosmology from neutrino mixing

NASA Astrophysics Data System (ADS)

Csáki, Csaba; Kuflik, Eric; Lombardo, Salvator

2017-09-01

Twin Higgs models solve the little hierarchy problem without introducing new colored particles; however, they are often in tension with measurements of the radiation density at late times. Here we explore viable cosmological histories for twin Higgs models. In particular, we show that mixing between the Standard Model (SM) and twin neutrinos can thermalize the two sectors below the twin QCD phase transition, significantly reducing the twin sector's contribution to the radiation density. The requisite twin neutrino masses of O (1 - 20 ) GeV and mixing angle with SM neutrinos of 10-3-10-5 can be probed in a variety of current and planned experiments. We further find that these parameters can be naturally accessed in a warped UV completion, where the neutrino sector can also generate the Z2-breaking Higgs mass term needed to produce the hierarchy between the symmetry breaking scales f and v .

Cosmology and accelerator tests of strongly interacting dark matter

NASA Astrophysics Data System (ADS)

Berlin, Asher; Blinov, Nikita; Gori, Stefania; Schuster, Philip; Toro, Natalia

2018-03-01

A natural possibility for dark matter is that it is composed of the stable pions of a QCD-like hidden sector. Existing literature largely assumes that pion self-interactions alone control the early universe cosmology. We point out that processes involving vector mesons typically dominate the physics of dark matter freeze-out and significantly widen the viable mass range for these models. The vector mesons also give rise to striking signals at accelerators. For example, in most of the cosmologically favored parameter space, the vector mesons are naturally long-lived and produce standard model particles in their decays. Electron and proton beam fixed-target experiments such as HPS, SeaQuest, and LDMX can exploit these signals to explore much of the viable parameter space. We also comment on dark matter decay inherent in a large class of previously considered models and explain how to ensure dark matter stability.

Renormalization group equation analysis of a pseudoscalar portal dark matter model

NASA Astrophysics Data System (ADS)

Ghorbani, Karim

2017-10-01

We investigate the vacuum stability and perturbativity of a pseudoscalar portal dark matter (DM) model with a Dirac DM candidate, through the renormalization group equation analysis at one-loop order. The model has a particular feature which can evade the direct detection upper bounds measured by XENON100 and even that from planned experiment XENON1T. We first find the viable regions in the parameter space which will give rise to correct DM relic density and comply with the constraints from Higgs physics. We show that for a given mass of the pseudoscalar, the mixing angle plays no significant role in the running of the couplings. Then we study the running of the couplings for various pseudoscalar masses at mixing angle θ =6^\\circ , and find the scale of validity in terms of the dark coupling, {λ }d. Depending on our choice of the cutoff scale, the resulting viable parameter space will be determined.

Cosmology and accelerator tests of strongly interacting dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berlin, Asher; Blinov, Nikita; Gori, Stefania

A natural possibility for dark matter is that it is composed of the stable pions of a QCD-like hidden sector. Existing literature largely assumes that pion self-interactions alone control the early universe cosmology. We point out that processes involving vector mesons typically dominate the physics of dark matter freeze-out and significantly widen the viable mass range for these models. The vector mesons also give rise to striking signals at accelerators. For example, in most of the cosmologically favored parameter space, the vector mesons are naturally long-lived and produce standard model particles in their decays. Electron and proton beam fixed-target experimentsmore » such as HPS, SeaQuest, and LDMX can exploit these signals to explore much of the viable parameter space. As a result, we also comment on dark matter decay inherent in a large class of previously considered models and explain how to ensure dark matter stability.« less

Should Live Patient Licensing Examinations in Dentistry Be Discontinued? Two Viewpoints: Viewpoint 1: Alternative Assessment Models Are Not Yet Viable Replacements for Live Patients in Clinical Licensure Exams and Viewpoint 2: Ethical and Patient Care Concerns About Live Patient Exams Require Full Acceptance of Justifiable Alternatives.

PubMed

Chu, Tien-Min Gabriel; Makhoul, Nicholas M; Silva, Daniela Rodrigues; Gonzales, Theresa S; Letra, Ariadne; Mays, Keith A

2018-03-01

This Point/Counterpoint article addresses a long-standing but still-unresolved debate on the advantages and disadvantages of using live patients in dental licensure exams. Two contrasting viewpoints are presented. Viewpoint 1 supports the traditional use of live patients, arguing that other assessment models have not yet been demonstrated to be viable alternatives to the actual treatment of patients in the clinical licensure process. This viewpoint also contends that the use of live patients and inherent variances in live patient treatment represent the realities of daily private practice. Viewpoint 2 argues that the use of live patients in licensure exams needs to be discontinued considering those exams' ethical dilemmas of exposing patients to potential harm, as well as their lack of reliability and validity and limited scope. According to this viewpoint, the current presence of viable alternatives means that the risk of harm inherent in live patient exams can finally be eliminated and those exams replaced with other means to confirm that candidates are qualified for licensure to practice.

Experimental and Theoretical Investigation of Multispecies Oral Biofilm Resistance to Chlorhexidine Treatment

NASA Astrophysics Data System (ADS)

Shen, Ya; Zhao, Jia; de La Fuente-Núñez, César; Wang, Zhejun; Hancock, Robert E. W.; Roberts, Clive R.; Ma, Jingzhi; Li, Jun; Haapasalo, Markus; Wang, Qi

2016-06-01

We investigate recovery of multispecies oral biofilms following chlorhexidine gluconate (CHX) and CHX with surface modifiers (CHX-Plus) treatment. Specifically, we examine the percentage of viable bacteria in the biofilms following their exposure to CHX and CHX-Plus for 1, 3, and 10 minutes, respectively. Before antimicrobial treatment, the biofilms are allowed to grow for three weeks. We find that (a). CHX-Plus kills bacteria in biofilms more effectively than the regular 2% CHX does, (b). cell continues to be killed for up to one week after exposure to the CHX solutions, (c). the biofilms start to recover after two weeks, the percentage of the viable bacteria recovers in the 1 and 3 minutes treatment groups but not in the 10 minutes treatment group after five weeks, and the biofilms fully return to the pretreatment levels after eight weeks. To understand the mechanism, a mathematical model for multiple bacterial phenotypes is developed, adopting the notion that bacterial persisters exist in the biofilms together with regulatory quorum sensing molecules and growth factor proteins. The model reveals the crucial role played by the persisters, quorum sensing molecules, and growth factors in biofilm recovery, accurately predicting the viable bacterial population after CHX treatment.

[Sustainability and excellence of the Catalan health system. New paradigms, challenges and responses].

PubMed

Fernández i Alegre, Roser; Argenter i Giralt, Miquel; Rodríguez i Guasch, Xavier

2015-11-01

The aim of a health system and the priority of any government is to anticipate problems before they appear, provide an innovative response to these new needs and healthcare models, improve access of the general public and patients to health care, especially care for the most vulnerable groups, improve healthcare results and implement the structural reforms necessary to maintain a viable and sustainable quality public healthcare system for everyone. In the current environment, health systems are facing new economic, demographic, care, social, technological and political paradigms to which health policy must respond. Faced with these challenges, health systems, especially in the case of Catalonia, are challenged to take decisions on how best to approach the implementation of structural reform designed to facilitate the necessary economic and fiscal sustainability in the service of fresh and innovative health policies and patient-centred care within a system marked by excellence and equity. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

A Structural Model of Prospective Science Teachers' Nature of Science Views

ERIC Educational Resources Information Center

Mugaloglu, Ebru Z.; Bayram, Hale

2010-01-01

This study aims to establish a viable structural model of prospective science teachers' nature of science (NOS) views, which could be used as an analytical tool for understanding the complex relationships between prospective teachers' conceptions of NOS and factors possibly affecting their conceptions. In order to construct such a model, likely…

LQG/LTR optimal attitude control of small flexible spacecraft using free-free boundary conditions

NASA Astrophysics Data System (ADS)

Fulton, Joseph M.

Due to the volume and power limitations of a small satellite, careful consideration must be taken while designing an attitude control system for 3-axis stabilization. Placing redundancy in the system proves difficult and utilizing power hungry, high accuracy, active actuators is not a viable option. Thus, it is customary to find dependable, passive actuators used in conjunction with small scale active control components. This document describes the application of Elastic Memory Composite materials in the construction of a flexible spacecraft appendage, such as a gravity gradient boom. Assumed modes methods are used with Finite Element Modeling information to obtain the equations of motion for the system while assuming free-free boundary conditions. A discussion is provided to illustrate how cantilever mode shapes are not always the best assumption when modeling small flexible spacecraft. A key point of interest is first resonant modes may be needed in the system design plant in spite of these modes being greater than one order of magnitude in frequency when compared to the crossover frequency of the controller. LQG/LTR optimal control techniques are implemented to compute attitude control gains while controller robustness considerations determine appropriate reduced order controllers and which flexible modes to include in the design model. Key satellite designer concerns in the areas of computer processor sizing, material uncertainty impacts on the system model, and system performance variations resulting from appendage length modifications are addressed.

The Design and Implementation of Eco-Evolutionary PVA Models: An Integrative Approach Using HexSim

EPA Science Inventory

To persist into the future, species of conservation concern must remain both demographically and genetically viable. Developing mitigation and recovery strategies to ensure species’ viability necessitates the use of forecasting models that can incorporate ecological and/or...

EDNA: Expert fault digraph analysis using CLIPS

NASA Technical Reports Server (NTRS)

Dixit, Vishweshwar V.

1990-01-01

Traditionally fault models are represented by trees. Recently, digraph models have been proposed (Sack). Digraph models closely imitate the real system dependencies and hence are easy to develop, validate and maintain. However, they can also contain directed cycles and analysis algorithms are hard to find. Available algorithms tend to be complicated and slow. On the other hand, the tree analysis (VGRH, Tayl) is well understood and rooted in vast research effort and analytical techniques. The tree analysis algorithms are sophisticated and orders of magnitude faster. Transformation of a digraph (cyclic) into trees (CLP, LP) is a viable approach to blend the advantages of the representations. Neither the digraphs nor the trees provide the ability to handle heuristic knowledge. An expert system, to capture the engineering knowledge, is essential. We propose an approach here, namely, expert network analysis. We combine the digraph representation and tree algorithms. The models are augmented by probabilistic and heuristic knowledge. CLIPS, an expert system shell from NASA-JSC will be used to develop a tool. The technique provides the ability to handle probabilities and heuristic knowledge. Mixed analysis, some nodes with probabilities, is possible. The tool provides graphics interface for input, query, and update. With the combined approach it is expected to be a valuable tool in the design process as well in the capture of final design knowledge.

Absence, Legitimacy and System Size.

ERIC Educational Resources Information Center

Gibson, R. Oliver

As school systems grow both vertically and horizontally, they face forces tending both to unify (centripetal) and to disunify (centrifugal). A viable system growth involves a blend of both forces on both vertical and horizontal dimensions. It is often assumed that the disunifying impact of centrifugal forces is of such proportion that the…

Day-Ahead Crude Oil Price Forecasting Using a Novel Morphological Component Analysis Based Model

PubMed Central

Zhu, Qing; Zou, Yingchao; Lai, Kin Keung

2014-01-01

As a typical nonlinear and dynamic system, the crude oil price movement is difficult to predict and its accurate forecasting remains the subject of intense research activity. Recent empirical evidence suggests that the multiscale data characteristics in the price movement are another important stylized fact. The incorporation of mixture of data characteristics in the time scale domain during the modelling process can lead to significant performance improvement. This paper proposes a novel morphological component analysis based hybrid methodology for modeling the multiscale heterogeneous characteristics of the price movement in the crude oil markets. Empirical studies in two representative benchmark crude oil markets reveal the existence of multiscale heterogeneous microdata structure. The significant performance improvement of the proposed algorithm incorporating the heterogeneous data characteristics, against benchmark random walk, ARMA, and SVR models, is also attributed to the innovative methodology proposed to incorporate this important stylized fact during the modelling process. Meanwhile, work in this paper offers additional insights into the heterogeneous market microstructure with economic viable interpretations. PMID:25061614

Gamma rays from dark matter annihilation in three-loop radiative neutrino mass generation models

NASA Astrophysics Data System (ADS)

Chowdhury, Talal Ahmed; Nasri, Salah

2018-07-01

We present the Sommerfeld enhanced Dark Matter (DM) annihilation into gamma ray for a class of three-loop radiative neutrino mass models with large electroweak multiplets where the DM mass is in O(TeV) range. We show that in this model, the DM annihilation rate becomes more prominent for larger multiplets and it is already within the reach of currently operating Imaging Atmospheric Cherenkov telescopes (IACTs), High Energy Stereoscopic System (H.E.S.S.). Furthermore, Cherenkov Telescope Array (CTA), which will begin operating in 2030, will improve this sensitivity by a factor of O (10) and may exclude a large portion of parameter space of this radiative neutrino mass model with larger electroweak multiplet. This implies that the only viable option is the model with lowest electroweak multiplets i.e. singlets of SU(2)L where the DM annihilation rate is not Sommerfeld enhanced and hence it is not yet constrained by the indirect detection limits from H.E.S.S. or future CTA.

Day-ahead crude oil price forecasting using a novel morphological component analysis based model.

PubMed

Zhu, Qing; He, Kaijian; Zou, Yingchao; Lai, Kin Keung

2014-01-01

As a typical nonlinear and dynamic system, the crude oil price movement is difficult to predict and its accurate forecasting remains the subject of intense research activity. Recent empirical evidence suggests that the multiscale data characteristics in the price movement are another important stylized fact. The incorporation of mixture of data characteristics in the time scale domain during the modelling process can lead to significant performance improvement. This paper proposes a novel morphological component analysis based hybrid methodology for modeling the multiscale heterogeneous characteristics of the price movement in the crude oil markets. Empirical studies in two representative benchmark crude oil markets reveal the existence of multiscale heterogeneous microdata structure. The significant performance improvement of the proposed algorithm incorporating the heterogeneous data characteristics, against benchmark random walk, ARMA, and SVR models, is also attributed to the innovative methodology proposed to incorporate this important stylized fact during the modelling process. Meanwhile, work in this paper offers additional insights into the heterogeneous market microstructure with economic viable interpretations.

Cognitive performance modeling based on general systems performance theory.

PubMed

Kondraske, George V

2010-01-01

General Systems Performance Theory (GSPT) was initially motivated by problems associated with quantifying different aspects of human performance. It has proved to be invaluable for measurement development and understanding quantitative relationships between human subsystem capacities and performance in complex tasks. It is now desired to bring focus to the application of GSPT to modeling of cognitive system performance. Previous studies involving two complex tasks (i.e., driving and performing laparoscopic surgery) and incorporating measures that are clearly related to cognitive performance (information processing speed and short-term memory capacity) were revisited. A GSPT-derived method of task analysis and performance prediction termed Nonlinear Causal Resource Analysis (NCRA) was employed to determine the demand on basic cognitive performance resources required to support different levels of complex task performance. This approach is presented as a means to determine a cognitive workload profile and the subsequent computation of a single number measure of cognitive workload (CW). Computation of CW may be a viable alternative to measuring it. Various possible "more basic" performance resources that contribute to cognitive system performance are discussed. It is concluded from this preliminary exploration that a GSPT-based approach can contribute to defining cognitive performance models that are useful for both individual subjects and specific groups (e.g., military pilots).

Memetic computing through bio-inspired heuristics integration with sequential quadratic programming for nonlinear systems arising in different physical models.

PubMed

Raja, Muhammad Asif Zahoor; Kiani, Adiqa Kausar; Shehzad, Azam; Zameer, Aneela

2016-01-01

In this study, bio-inspired computing is exploited for solving system of nonlinear equations using variants of genetic algorithms (GAs) as a tool for global search method hybrid with sequential quadratic programming (SQP) for efficient local search. The fitness function is constructed by defining the error function for systems of nonlinear equations in mean square sense. The design parameters of mathematical models are trained by exploiting the competency of GAs and refinement are carried out by viable SQP algorithm. Twelve versions of the memetic approach GA-SQP are designed by taking a different set of reproduction routines in the optimization process. Performance of proposed variants is evaluated on six numerical problems comprising of system of nonlinear equations arising in the interval arithmetic benchmark model, kinematics, neurophysiology, combustion and chemical equilibrium. Comparative studies of the proposed results in terms of accuracy, convergence and complexity are performed with the help of statistical performance indices to establish the worth of the schemes. Accuracy and convergence of the memetic computing GA-SQP is found better in each case of the simulation study and effectiveness of the scheme is further established through results of statistics based on different performance indices for accuracy and complexity.

Creating an isotopically similar Earth-Moon system with correct angular momentum from a giant impact

NASA Astrophysics Data System (ADS)

Wyatt, Bryant M.; Petz, Jonathan M.; Sumpter, William J.; Turner, Ty R.; Smith, Edward L.; Fain, Baylor G.; Hutyra, Taylor J.; Cook, Scott A.; Gresham, John H.; Hibbs, Michael F.; Goderya, Shaukat N.

2018-04-01

The giant impact hypothesis is the dominant theory explaining the formation of our Moon. However, the inability to produce an isotopically similar Earth-Moon system with correct angular momentum has cast a shadow on its validity. Computer-generated impacts have been successful in producing virtual systems that possess many of the observed physical properties. However, addressing the isotopic similarities between the Earth and Moon coupled with correct angular momentum has proven to be challenging. Equilibration and evection resonance have been proposed as means of reconciling the models. In the summer of 2013, the Royal Society called a meeting solely to discuss the formation of the Moon. In this meeting, evection resonance and equilibration were both questioned as viable means of removing the deficiencies from giant impact models. The main concerns were that models were multi-staged and too complex. We present here initial impact conditions that produce an isotopically similar Earth-Moon system with correct angular momentum. This is done in a single-staged simulation. The initial parameters are straightforward and the results evolve solely from the impact. This was accomplished by colliding two roughly half-Earth-sized impactors, rotating in approximately the same plane in a high-energy, off-centered impact, where both impactors spin into the collision.

Let's Get Real About Health Care Reform.

PubMed

Karpf, Michael

2017-09-01

In light of the ongoing debate about health care policy in the United States, including efforts to repeal and replace the Affordable Care Act, it will be critically important for the academic community to engage in the dialogue. Developing a viable approach to health care reform requires an understanding of the interaction and interdependence between choice, cost, and coverage in a competitive and functional market-based system. Some institutions have implemented models that indicate the feasibility of providing high-quality, efficient patient care while working within fixed budgets. The academic community must stay engaged in these conversations because of its moral commitment to equitable access to health care for all. Academic medical centers will also have to define and protect their roles in an evolving health care delivery system in the United States.

Analysis of a diffuse interface model of multispecies tumor growth

NASA Astrophysics Data System (ADS)

Dai, Mimi; Feireisl, Eduard; Rocca, Elisabetta; Schimperna, Giulio; Schonbek, Maria E.

2017-04-01

We consider a diffuse interface model for tumor growth recently proposed in Chen et al (2014 Int. J. Numer. Methods Biomed. Eng. 30 726-54). In this new approach sharp interfaces are replaced by narrow transition layers arising due to adhesive forces among the cell species. Hence, a continuum thermodynamically consistent model is introduced. The resulting PDE system couples four different types of equations: a Cahn-Hilliard type equation for the tumor cells (which include proliferating and dead cells), a Darcy law for the tissue velocity field, whose divergence may be different from 0 and depend on the other variables, a transport equation for the proliferating (viable) tumor cells, and a quasi-static reaction diffusion equation for the nutrient concentration. We establish existence of weak solutions for the PDE system coupled with suitable initial and boundary conditions. In particular, the proliferation function at the boundary is supposed to be nonnegative on the set where the velocity \\mathbf{u} satisfies \\mathbf{u}\\centerdot ν >0 , where ν is the outer normal to the boundary of the domain.

Development and application of earth system models.

PubMed

Prinn, Ronald G

2013-02-26

The global environment is a complex and dynamic system. Earth system modeling is needed to help understand changes in interacting subsystems, elucidate the influence of human activities, and explore possible future changes. Integrated assessment of environment and human development is arguably the most difficult and most important "systems" problem faced. To illustrate this approach, we present results from the integrated global system model (IGSM), which consists of coupled submodels addressing economic development, atmospheric chemistry, climate dynamics, and ecosystem processes. An uncertainty analysis implies that without mitigation policies, the global average surface temperature may rise between 3.5 °C and 7.4 °C from 1981-2000 to 2091-2100 (90% confidence limits). Polar temperatures, absent policy, are projected to rise from about 6.4 °C to 14 °C (90% confidence limits). Similar analysis of four increasingly stringent climate mitigation policy cases involving stabilization of greenhouse gases at various levels indicates that the greatest effect of these policies is to lower the probability of extreme changes. The IGSM is also used to elucidate potential unintended environmental consequences of renewable energy at large scales. There are significant reasons for attention to climate adaptation in addition to climate mitigation that earth system models can help inform. These models can also be applied to evaluate whether "climate engineering" is a viable option or a dangerous diversion. We must prepare young people to address this issue: The problem of preserving a habitable planet will engage present and future generations. Scientists must improve communication if research is to inform the public and policy makers better.

A Technology Pathway for Airbreathing, Combined-Cycle, Horizontal Space Launch Through SR-71 Based Trajectory Modeling

NASA Technical Reports Server (NTRS)

Kloesel, Kurt J.; Ratnayake, Nalin A.; Clark, Casie M.

2011-01-01

Access to space is in the early stages of commercialization. Private enterprises, mainly under direct or indirect subsidy by the government, have been making headway into the LEO launch systems infrastructure, of small-weight-class payloads of approximately 1000 lbs. These moderate gains have emboldened the launch industry and they are poised to move into the middle-weight class (roughly 5000 lbs). These commercially successful systems are based on relatively straightforward LOX-RP, two-stage, bi-propellant rocket technology developed by the government 40 years ago, accompanied by many technology improvements. In this paper we examine a known generic LOX-RP system with the focus on the booster stage (1st stage). The booster stage is then compared to modeled Rocket-Based and Turbine-Based Combined Cycle booster stages. The air-breathing propulsion stages are based on/or extrapolated from known performance parameters of ground tested RBCC (the Marquardt Ejector Ramjet) and TBCC (the SR-71/J-58 engine) data. Validated engine models using GECAT and SCCREAM are coupled with trajectory optimization and analysis in POST-II to explore viable launch scenarios using hypothetical aerospaceplane platform obeying the aerodynamic model of the SR-71. Finally, and assessment is made of the requisite research technology advances necessary for successful commercial and government adoption of combined-cycle engine systems for space access.

Beyond context to the skyline: thinking in 3D.

PubMed

Hoagwood, Kimberly; Olin, Serene; Cleek, Andrew

2013-01-01

Sweeping and profound structural, regulatory, and fiscal changes are rapidly reshaping the contours of health and mental health practice. The community-based practice contexts described in the excellent review by Garland and colleagues are being fundamentally altered with different business models, regional networks, accountability standards, and incentive structures. If community-based mental health services are to remain viable, the two-dimensional and flat research and practice paradigm has to be replaced with three-dimensional thinking. Failure to take seriously the changes that are happening to the larger healthcare context and respond actively through significant system redesign will lead to the demise of specialty mental health services.

Regulation of Protein Secretion Through Controlled Aggregation in the Endoplasmic Reticulum

NASA Astrophysics Data System (ADS)

Rivera, Victor M.; Wang, Xiurong; Wardwell, Scott; Courage, Nancy L.; Volchuk, Allen; Keenan, Terence; Holt, Dennis A.; Gilman, Michael; Orci, Lelio; Cerasoli, Frank; Rothman, James E.; Clackson, Tim

2000-02-01

A system for direct pharmacologic control of protein secretion was developed to allow rapid and pulsatile delivery of therapeutic proteins. A protein was engineered so that it accumulated as aggregates in the endoplasmic reticulum. Secretion was then stimulated by a synthetic small-molecule drug that induces protein disaggregation. Rapid and transient secretion of growth hormone and insulin was achieved in vitro and in vivo. A regulated pulse of insulin secretion resulted in a transient correction of serum glucose concentrations in a mouse model of hyperglycemia. This approach may make gene therapy a viable method for delivery of polypeptides that require rapid and regulated delivery.

Recommendation system to determine suitable and viable hiking routes: a prototype application in Sierra de las Nieves Nature Reserve (southern Spain)

NASA Astrophysics Data System (ADS)

Vías, Jesús; Rolland, José; Gómez, María Luisa; Ocaña, Carmen; Luque, Ana

2018-05-01

This paper describes a system for recommending hiking routes to help manage hiking activities in a protected area. The system proposes various routes, based on five criteria that maximize some aspects of hikers' requirements (by analyzing the viability and difficulty of the trails) and also those of protected areas managers (by proposals to relieve congestion in areas already used for hiking and to promote awareness of new ones, as a contribution to environmental education). The recommendation system uses network analysis, multi-criteria decision analysis and geographic information system by free software tools: PgRouting, PostgreSQL and PostGIS. This system has been tested in Sierra de las Nieves Nature Reserve (Andalusia, Spain). Of the 182 routes obtained by the system, 62 (34%) are considered viable for hikers in Sierra de las Nieves, taking into account the type of user most likely to visit this protected area. Most routes have a high difficulty level, which is coherent with the mountainous character of the protected area.

Biomedical devices and systems security.

PubMed

Arney, David; Venkatasubramanian, Krishna K; Sokolsky, Oleg; Lee, Insup

2011-01-01

Medical devices have been changing in revolutionary ways in recent years. One is in their form-factor. Increasing miniaturization of medical devices has made them wearable, light-weight, and ubiquitous; they are available for continuous care and not restricted to clinical settings. Further, devices are increasingly becoming connected to external entities through both wired and wireless channels. These two developments have tremendous potential to make healthcare accessible to everyone and reduce costs. However, they also provide increased opportunity for technology savvy criminals to exploit them for fun and profit. Consequently, it is essential to consider medical device security issues. In this paper, we focused on the challenges involved in securing networked medical devices. We provide an overview of a generic networked medical device system model, a comprehensive attack and adversary model, and describe some of the challenges present in building security solutions to manage the attacks. Finally, we provide an overview of two areas of research that we believe will be crucial for making medical device system security solutions more viable in the long run: forensic data logging, and building security assurance cases.

Ant system: optimization by a colony of cooperating agents.

PubMed

Dorigo, M; Maniezzo, V; Colorni, A

1996-01-01

An analogy with the way ant colonies function has suggested the definition of a new computational paradigm, which we call ant system (AS). We propose it as a viable new approach to stochastic combinatorial optimization. The main characteristics of this model are positive feedback, distributed computation, and the use of a constructive greedy heuristic. Positive feedback accounts for rapid discovery of good solutions, distributed computation avoids premature convergence, and the greedy heuristic helps find acceptable solutions in the early stages of the search process. We apply the proposed methodology to the classical traveling salesman problem (TSP), and report simulation results. We also discuss parameter selection and the early setups of the model, and compare it with tabu search and simulated annealing using TSP. To demonstrate the robustness of the approach, we show how the ant system (AS) can be applied to other optimization problems like the asymmetric traveling salesman, the quadratic assignment and the job-shop scheduling. Finally we discuss the salient characteristics-global data structure revision, distributed communication and probabilistic transitions of the AS.

Sustainable BECCS pathways evaluated by an integrated assessment model

NASA Astrophysics Data System (ADS)

Kato, E.

2017-12-01

Negative emissions technologies, particularly Bioenergy with Carbon Capture and Storage (BECCS), are key components of mitigation strategies in ambitious future socioeconomic scenarios analysed by integrated assessment models. Generally, scenarios aiming to keep mean global temperature rise below 2°C above pre-industrial would require net negative carbon emissions in the end of the 21st century. Also, in the context of Paris agreement which acknowledges "a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century", RD&D for the negative emissions technologies in this decade has a crucial role for the possibility of early deployment of the technology. Because of the requirement of potentially extensive use of land and water for producing the bioenergy feedstock to get the anticipated level of gross negative emissions, researches on how to develop sustainable scenarios of BECCS is needed. Here, we present BECCS deployment scenarios that consider economically viable flow of bioenergy system including power generation and conversion process to liquid and gaseous fuels for transportation and heat with consideration of sustainable global biomass use. In the modelling process, detailed bioenergy representations, i.e. various feedstock and conversion technologies with and without CCS, are implemented in an integrated assessment (IA) model GRAPE (Global Relationship Assessment to Protect the Environment). Also, to overcome a general discrepancy about assumed future agricultural yield between 'top-down' IA models and 'bottom-up' estimates, which would crucially affect the land-use pattern, we applied yields change of food and energy crops consistent with process-based biophysical crop models in consideration of changing climate conditions. Using the framework, economically viable strategy for implementing sustainable bioenergy and BECCS flow are evaluated in the scenarios targeting to keep global average temperature rise below 2°C and/or 1.5°C above pre-industrial.

Research on application model of blockchain technology in distributed electricity market

NASA Astrophysics Data System (ADS)

Cheng, S.; Zeng, B.; Huang, Y. Z.

2017-11-01

In the context of current energy Internet, the emergence of a large number of energy productive consumers will create a new business model. In the decentralized electricity market, the cost of traditional centralized solution construction, management and maintenance is too high, and it is difficult to support the collection, transmission, reception, storage and analysis of massive data. To provide a solution to this phenomenon, we apply the blockchain technology to this distributed electricity market to achieve peer to peer transactions in the power systems. The blockchain technology which is very popular nowadays will be used in power system to establish a credible direct transaction between devices. At first, this article analyzes the future direction of the development of power systems, studies the characteristics of decentralized power systems and summarizes the main issues in the development process. Then, we analyze the basic characteristics of blockchain and put forward a new transaction framework in consideration of problems existing in current energy market. The transaction framework is based on the blockchain technology in the distributed electricity market and includes the pricing method, the power transaction system architecture, various modules of the trading system and the details of the whole transaction system runtime. This framework provides a viable solution for increasingly complex energy transactions.

Simulation of an integrated system for the production of methane and single cell protein from biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, M.V.

1989-01-01

A numerical model was developed to simulate the operation of an integrated system for the production of methane and single-cell algal protein from a variety of biomass energy crops or waste streams. Economic analysis was performed at the end of each simulation. The model was capable of assisting in the determination of design parameters by providing relative economic information for various strategies. Three configurations of anaerobic reactors were simulated. These included fed-bed reactors, conventional stirred tank reactors, and continuously expanding reactors. A generic anaerobic digestion process model, using lumped substrate parameters, was developed for use by type-specific reactor models. Themore » generic anaerobic digestion model provided a tool for the testing of conversion efficiencies and kinetic parameters for a wide range of substrate types and reactor designs. Dynamic growth models were used to model the growth of algae and Eichornia crassipes was modeled as a function of daily incident radiation and temperature. The growth of Eichornia crassipes was modeled for the production of biomass as a substrate for digestion. Computer simulations with the system model indicated that tropical or subtropical locations offered the most promise for a viable system. The availability of large quantities of digestible waste and low land prices were found to be desirable in order to take advantage of the economies of scale. Other simulations indicated that poultry and swine manure produced larger biogas yields than cattle manure. The model was created in a modular fashion to allow for testing of a wide variety of unit operations. Coding was performed in the Pascal language for use on personal computers.« less

Energy efficient engine: Turbine transition duct model technology report

NASA Technical Reports Server (NTRS)

Leach, K.; Thurlin, R.

1982-01-01

The Low-Pressure Turbine Transition Duct Model Technology Program was directed toward substantiating the aerodynamic definition of a turbine transition duct for the Energy Efficient Engine. This effort was successful in demonstrating an aerodynamically viable compact duct geometry and the performance benefits associated with a low camber low-pressure turbine inlet guide vane. The transition duct design for the flight propulsion system was tested and the pressure loss goal of 0.7 percent was verified. Also, strut fairing pressure distributions, as well as wall pressure coefficients, were in close agreement with analytical predictions. Duct modifications for the integrated core/low spool were also evaluated. The total pressure loss was 1.59 percent. Although the increase in exit area in this design produced higher wall loadings, reflecting a more aggressive aerodynamic design, pressure profiles showed no evidence of flow separation. Overall, the results acquired have provided pertinent design and diagnostic information for the design of a turbine transition duct for both the flight propulsion system and the integrated core/low spool.

Porous media of the Red River Formation, Williston Basin, North Dakota: a possible Sedimentary Enhanced Geothermal System

NASA Astrophysics Data System (ADS)

Hartig, Caitlin M.

2018-01-01

Fracture-stimulated enhanced geothermal systems (EGS) can be developed in both crystalline rocks and sedimentary basins. The Red River Formation (Ordovician) is a viable site for development of a sedimentary EGS (SEGS) because the formation temperatures exceed 140 °C and the permeability is 0.1-38 mD; fracture stimulation can be utilized to improve permeability. The spatial variations of the properties of the Red River Formation were analyzed across the study area in order to understand the distribution of subsurface formation temperatures. Maps of the properties of the Red River Formation-including depth to the top of the formation, depth to the bottom of the formation, porosity, geothermal gradient, heat flow, and temperature-were produced by the Kriging interpolation method in ArcGIS. In the future, these results may be utilized to create a reservoir simulation model of an SEGS in the Red River Formation; the purpose of this model would be to ascertain the thermal response of the reservoir to fracture stimulation.

Enterocolic lymphocytic phlebitis: statistical analysis of histology features in viable and ischemic bowel.

PubMed

Medlicott, Shaun A C; Guggisberg, Kelly A; DesCôteaux, Jean-Gaston; Beck, Paul

2006-07-01

Enterocolic lymphocytic phlebitis is a rare cause of segmental ischemic enterocolitis. This artery-sparing transmural vasculitis is classically a circumferential phlebitis with perivenular lymphocyte cuffing and thrombi in the absence of systemic manifestations. Myointimal hyperplasia may represent a chronic phase of enterocolic lymphocytic phlebitis. Subclinical or early stage enterocolic lymphocytic phlebitis is not well delineated. We analyzed 600 submucosal and subserosal veins from both ischemic and intact bowel segments to discern if vascular morphology varied between sites. Crescentic and circumferential lymphocytic phlebitis is more common in viable bowel than in the ischemic segment. A nonsignificant trend was found for increased crescentic morphology between intact bowel remote from the ischemic focus compared with that adjacent to the ischemic focus. Hallmarks of ischemic bowel are necrotizing phlebitis and thrombi formation. Thrombophlebitis morphology is distinctly different in viable and ischemic bowel, changing from the classic lymphocytic to necrotizing lesions respectively.

Space, time, and the third dimension (model error)

USGS Publications Warehouse

Moss, Marshall E.

1979-01-01

The space-time tradeoff of hydrologic data collection (the ability to substitute spatial coverage for temporal extension of records or vice versa) is controlled jointly by the statistical properties of the phenomena that are being measured and by the model that is used to meld the information sources. The control exerted on the space-time tradeoff by the model and its accompanying errors has seldom been studied explicitly. The technique, known as Network Analyses for Regional Information (NARI), permits such a study of the regional regression model that is used to relate streamflow parameters to the physical and climatic characteristics of the drainage basin.The NARI technique shows that model improvement is a viable and sometimes necessary means of improving regional data collection systems. Model improvement provides an immediate increase in the accuracy of regional parameter estimation and also increases the information potential of future data collection. Model improvement, which can only be measured in a statistical sense, cannot be quantitatively estimated prior to its achievement; thus an attempt to upgrade a particular model entails a certain degree of risk on the part of the hydrologist.

Adaptive control of artificial pancreas systems - a review.

PubMed

Turksoy, Kamuran; Cinar, Ali

2014-01-01

Artificial pancreas (AP) systems offer an important improvement in regulating blood glucose concentration for patients with type 1 diabetes, compared to current approaches. AP consists of sensors, control algorithms and an insulin pump. Different AP control algorithms such as proportional-integral-derivative, model-predictive control, adaptive control, and fuzzy logic control have been investigated in simulation and clinical studies in the past three decades. The variability over time and complexity of the dynamics of blood glucose concentration, unsteady disturbances such as meals, time-varying delays on measurements and insulin infusion, and noisy data from sensors create a challenging system to AP. Adaptive control is a powerful control technique that can deal with such challenges. In this paper, a review of adaptive control techniques for blood glucose regulation with an AP system is presented. The investigations and advances in technology produced impressive results, but there is still a need for a reliable AP system that is both commercially viable and appealing to patients with type 1 diabetes.

IVAN: Intelligent Van for the Distribution of Pharmaceutical Drugs

PubMed Central

Moreno, Asier; Angulo, Ignacio; Perallos, Asier; Landaluce, Hugo; Zuazola, Ignacio Julio García; Azpilicueta, Leire; Astrain, José Javier; Falcone, Francisco; Villadangos, Jesús

2012-01-01

This paper describes a telematic system based on an intelligent van which is capable of tracing pharmaceutical drugs over delivery routes from a warehouse to pharmacies, without altering carriers' daily conventional tasks. The intelligent van understands its environment, taking into account its location, the assets and the predefined delivery route; with the capability of reporting incidences to carriers in case of failure according to the established distribution plan. It is a non-intrusive solution which represents a successful experience of using smart environments and an optimized Radio Frequency Identification (RFID) embedded system in a viable way to resolve a real industrial need in the pharmaceutical industry. The combination of deterministic modeling of the indoor vehicle, the implementation of an ad-hoc radiating element and an agile software platform within an overall system architecture leads to a competitive, flexible and scalable solution. PMID:22778659

The point system for driver license administration : a viable alternative for Virginia?.

DOT National Transportation Integrated Search

1972-01-01

Traffic safety research was noted to have been unable to produce any empirical evidence that the introduction of a point system would affect, either negatively or positively, traffic accident statistics. In view of this absence of evidence, the simil...

Wireless GPS fleet tracking system at the University of Albany.

DOT National Transportation Integrated Search

2014-07-01

This report provides an overview of the project undertaken at the University at Albany to make alternative transportation a more : viable option by implementing a GPS Tracking System on the University bus fleet and broadcasting the bus locations to c...

Economic evaluation of the Annual Cycle Energy System (ACES). Volume 1: Executive summary

NASA Astrophysics Data System (ADS)

1980-05-01

Three different classes of building are investigated, namely: single family residence; multifamily residence; and commercial office building. For each building type in each geographic location, the economic evaluation of the annual cycle energy system (ACES) is based on a comparison of the present worth of the ACES to the present worth of a number of conventional systems. The results of this analysis indicate that the economic viability of the ACES is very sensitive to the assumed value of the property tax, maintenance cost, and fuel escalation rates, while it is relatively insensitive to the assumed values of other parameters. Fortunately, any conceivable change in the fuel escalation rates would tend to increase the viability of the ACES concept. An increase in the assumed value of the maintenance cost or property tax would tend to make the ACES concept less viable; a decrease in either would tend to make the ACES concept more viable.

Non-Linear Approach in Kinesiology Should Be Preferred to the Linear--A Case of Basketball.

PubMed

Trninić, Marko; Jeličić, Mario; Papić, Vladan

2015-07-01

In kinesiology, medicine, biology and psychology, in which research focus is on dynamical self-organized systems, complex connections exist between variables. Non-linear nature of complex systems has been discussed and explained by the example of non-linear anthropometric predictors of performance in basketball. Previous studies interpreted relations between anthropometric features and measures of effectiveness in basketball by (a) using linear correlation models, and by (b) including all basketball athletes in the same sample of participants regardless of their playing position. In this paper the significance and character of linear and non-linear relations between simple anthropometric predictors (AP) and performance criteria consisting of situation-related measures of effectiveness (SE) in basketball were determined and evaluated. The sample of participants consisted of top-level junior basketball players divided in three groups according to their playing time (8 minutes and more per game) and playing position: guards (N = 42), forwards (N = 26) and centers (N = 40). Linear (general model) and non-linear (general model) regression models were calculated simultaneously and separately for each group. The conclusion is viable: non-linear regressions are frequently superior to linear correlations when interpreting actual association logic among research variables.

A smartphone photogrammetry method for digitizing prosthetic socket interiors.

PubMed

Hernandez, Amaia; Lemaire, Edward

2017-04-01

Prosthetic CAD/CAM systems require accurate 3D limb models; however, difficulties arise when working from the person's socket since current 3D scanners have difficulties scanning socket interiors. While dedicated scanners exist, they are expensive and the cost may be prohibitive for a limited number of scans per year. A low-cost and accessible photogrammetry method for socket interior digitization is proposed, using a smartphone camera and cloud-based photogrammetry services. 15 two-dimensional images of the socket's interior are captured using a smartphone camera. A 3D model is generated using cloud-based software. Linear measurements were comparing between sockets and the related 3D models. 3D reconstruction accuracy averaged 2.6 ± 2.0 mm and 0.086 ± 0.078 L, which was less accurate than models obtained by high quality 3D scanners. However, this method would provide a viable 3D digital socket reproduction that is accessible and low-cost, after processing in prosthetic CAD software. Clinical relevance The described method provides a low-cost and accessible means to digitize a socket interior for use in prosthetic CAD/CAM systems, employing a smartphone camera and cloud-based photogrammetry software.

Flow dynamics in hyper-saline aquifers: hydro-geophysical monitoring and modeling

NASA Astrophysics Data System (ADS)

Haaken, Klaus; Piero Deidda, Gian; Cassiani, Giorgio; Deiana, Rita; Putti, Mario; Paniconi, Claudio; Scudeler, Carlotta; Kemna, Andreas

2017-03-01

Saline-freshwater interaction in porous media is a phenomenon of practical interest particularly for the management of water resources in arid and semi-arid environments, where precious freshwater resources are threatened by seawater intrusion and where storage of freshwater in saline aquifers can be a viable option. Saline-freshwater interactions are controlled by physico-chemical processes that need to be accurately modeled. This in turn requires monitoring of these systems, a non-trivial task for which spatially extensive, high-resolution non-invasive techniques can provide key information. In this paper we present the field monitoring and numerical modeling components of an approach aimed at understanding complex saline-freshwater systems. The approach is applied to a freshwater injection experiment carried out in a hyper-saline aquifer near Cagliari (Sardinia, Italy). The experiment was monitored using time-lapse cross-hole electrical resistivity tomography (ERT). To investigate the flow dynamics, coupled numerical flow and transport modeling of the experiment was carried out using an advanced three-dimensional (3-D) density-driven flow-transport simulator. The simulation results were used to produce synthetic ERT inversion results to be compared against real field ERT results. This exercise demonstrates that the evolution of the freshwater bulb is strongly influenced by the system's (even mild) hydraulic heterogeneities. The example also highlights how the joint use of ERT imaging and gravity-dependent flow and transport modeling give fundamental information for this type of study.

Telerobotic control of a mobile coordinated robotic server. M.S. Thesis Annual Technical Report

NASA Technical Reports Server (NTRS)

Lee, Gordon

1993-01-01

The annual report on telerobotic control of a mobile coordinated robotic server is presented. The goal of this effort is to develop advanced control methods for flexible space manipulator systems. As such, an adaptive fuzzy logic controller was developed in which model structure as well as parameter constraints are not required for compensation. The work builds upon previous work on fuzzy logic controllers. Fuzzy logic controllers have been growing in importance in the field of automatic feedback control. Hardware controllers using fuzzy logic have become available as an alternative to the traditional PID controllers. Software has also been introduced to aid in the development of fuzzy logic rule-bases. The advantages of using fuzzy logic controllers include the ability to merge the experience and intuition of expert operators into the rule-base and that a model of the system is not required to construct the controller. A drawback of the classical fuzzy logic controller, however, is the many parameters needed to be turned off-line prior to application in the closed-loop. In this report, an adaptive fuzzy logic controller is developed requiring no system model or model structure. The rule-base is defined to approximate a state-feedback controller while a second fuzzy logic algorithm varies, on-line, parameters of the defining controller. Results indicate the approach is viable for on-line adaptive control of systems when the model is too complex or uncertain for application of other more classical control techniques.

Distributed and decentralized state estimation in gas networks as distributed parameter systems.

PubMed

Ahmadian Behrooz, Hesam; Boozarjomehry, R Bozorgmehry

2015-09-01

In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline networks. In the construction of local models, due to the existence of common states and interconnections among the subsystems, the assimilation and prediction steps of the Kalman filter are modified to take the overlapping and external states into account. However, dynamic Riccati equation for each subsystem is constructed based on the local model, which introduces a maximum error of 5% in the estimated standard deviation of the states in the benchmarks studied in this paper. The performance of the proposed methodology has been shown based on the comparison of its accuracy and computational demands against their counterparts in centralized Kalman filter for two viable benchmarks. In a real life network, it is shown that while the accuracy is not significantly decreased, the real-time factor of the state estimation is increased by a factor of 10. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Ability of bed bug-detecting canines to locate live bed bugs and viable bed bug eggs.

PubMed

Pfiester, Margie; Koehler, Philip G; Pereira, Roberto M

2008-08-01

The bed bug, Cimex lectularius L., like other bed bug species, is difficult to visually locate because it is cryptic. Detector dogs are useful for locating bed bugs because they use olfaction rather than vision. Dogs were trained to detect the bed bug (as few as one adult male or female) and viable bed bug eggs (five, collected 5-6 d after feeding) by using a modified food and verbal reward system. Their efficacy was tested with bed bugs and viable bed bug eggs placed in vented polyvinyl chloride containers. Dogs were able to discriminate bed bugs from Camponotus floridanus Buckley, Blattella germanica (L.), and Reticulitermes flavipes (Kollar), with a 97.5% positive indication rate (correct indication of bed bugs when present) and 0% false positives (incorrect indication of bed bugs when not present). Dogs also were able to discriminate live bed bugs and viable bed bug eggs from dead bed bugs, cast skins, and feces, with a 95% positive indication rate and a 3% false positive rate on bed bug feces. In a controlled experiment in hotel rooms, dogs were 98% accurate in locating live bed bugs. A pseudoscent prepared from pentane extraction of bed bugs was recognized by trained dogs as bed bug scent (100% indication). The pseudoscent could be used to facilitate detector dog training and quality assurance programs. If trained properly, dogs can be used effectively to locate live bed bugs and viable bed bug eggs.

Modelling CO2 flow in naturally fractured geological media using MINC and multiple subregion upscaling procedure

NASA Astrophysics Data System (ADS)

Tatomir, Alexandru Bogdan A. C.; Flemisch, Bernd; Class, Holger; Helmig, Rainer; Sauter, Martin

2017-04-01

Geological storage of CO2 represents one viable solution to reduce greenhouse gas emission in the atmosphere. Potential leakage of CO2 storage can occur through networks of interconnected fractures. The geometrical complexity of these networks is often very high involving fractures occurring at various scales and having hierarchical structures. Such multiphase flow systems are usually hard to solve with a discrete fracture modelling (DFM) approach. Therefore, continuum fracture models assuming average properties are usually preferred. The multiple interacting continua (MINC) model is an extension of the classic double porosity model (Warren and Root, 1963) which accounts for the non-linear behaviour of the matrix-fracture interactions. For CO2 storage applications the transient representation of the inter-porosity two phase flow plays an important role. This study tests the accuracy and computational efficiency of the MINC method complemented with the multiple sub-region (MSR) upscaling procedure versus the DFM. The two phase flow MINC simulator is implemented in the free-open source numerical toolbox DuMux (www.dumux.org). The MSR (Gong et al., 2009) determines the inter-porosity terms by solving simplified local single-phase flow problems. The DFM is considered as the reference solution. The numerical examples consider a quasi-1D reservoir with a quadratic fracture system , a five-spot radial symmetric reservoir, and a completely random generated fracture system. Keywords: MINC, upscaling, two-phase flow, fractured porous media, discrete fracture model, continuum fracture model

Clinical Informatics Fellowship Programs: In Search of a Viable Financial Model: An open letter to the Centers for Medicare and Medicaid Services.

PubMed

Lehmann, C U; Longhurst, C A; Hersh, W; Mohan, V; Levy, B P; Embi, P J; Finnell, J T; Turner, A M; Martin, R; Williamson, J; Munger, B

2015-01-01

In the US, the new subspecialty of Clinical Informatics focuses on systems-level improvements in care delivery through the use of health information technology (HIT), data analytics, clinical decision support, data visualization and related tools. Clinical informatics is one of the first subspecialties in medicine open to physicians trained in any primary specialty. Clinical Informatics benefits patients and payers such as Medicare and Medicaid through its potential to reduce errors, increase safety, reduce costs, and improve care coordination and efficiency. Even though Clinical Informatics benefits patients and payers, because GME funding from the Centers for Medicare and Medicaid Services (CMS) has not grown at the same rate as training programs, the majority of the cost of training new Clinical Informaticians is currently paid by academic health science centers, which is unsustainable. To maintain the value of HIT investments by the government and health care organizations, we must train sufficient leaders in Clinical Informatics. In the best interest of patients, payers, and the US society, it is therefore critical to find viable financial models for Clinical Informatics fellowship programs. To support the development of adequate training programs in Clinical Informatics, we request that the Centers for Medicare and Medicaid Services (CMS) issue clarifying guidance that would allow accredited ACGME institutions to bill for clinical services delivered by fellows at the fellowship program site within their primary specialty.

21 CFR 173.160 - Candida guilliermondii.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and...: (a) The food additive is the enzyme system of the viable organism Candida guilliermondii and its...

Designing a Measurement Framework for Response to Intervention in Early Childhood Programs

ERIC Educational Resources Information Center

McConnell, Scott R.; Wackerle-Hollman, Alisha K.; Roloff, Tracy A.; Rodriguez, Michael

2014-01-01

The overall architecture and major components of a measurement system designed and evaluated to support Response to Intervention (RTI) in the areas of language and literacy in early childhood programs are described. Efficient and reliable measurement is essential for implementing any viable RTI system, and implementing such a system in early…

Sediment and PM10 flux from no-tillage cropping systems in the Pacific Northwest

USDA-ARS?s Scientific Manuscript database

Wind erosion is a concern in the Inland Pacific Northwest (PNW) United States where the emission of fine particulates from winter wheat – summer fallow (WW/SF) dryland cropping systems during high winds degrade air quality. Although no-tillage cropping systems are not yet economically viable, these ...

Evolutionary Concepts for Decentralized Air Traffic Flow Management

NASA Technical Reports Server (NTRS)

Adams, Milton; Kolitz, Stephan; Milner, Joseph; Odoni, Amedeo

1997-01-01

Alternative concepts for modifying the policies and procedures under which the air traffic flow management system operates are described, and an approach to the evaluation of those concepts is discussed. Here, air traffic flow management includes all activities related to the management of the flow of aircraft and related system resources from 'block to block.' The alternative concepts represent stages in the evolution from the current system, in which air traffic management decision making is largely centralized within the FAA, to a more decentralized approach wherein the airlines and other airspace users collaborate in air traffic management decision making with the FAA. The emphasis in the discussion is on a viable medium-term partially decentralized scenario representing a phase of this evolution that is consistent with the decision-making approaches embodied in proposed Free Flight concepts for air traffic management. System-level metrics for analyzing and evaluating the various alternatives are defined, and a simulation testbed developed to generate values for those metrics is described. The fundamental issue of modeling airline behavior in decentralized environments is also raised, and an example of such a model, which deals with the preservation of flight bank integrity in hub airports, is presented.

Real-time hierarchically distributed processing network interaction simulation

NASA Technical Reports Server (NTRS)

Zimmerman, W. F.; Wu, C.

1987-01-01

The Telerobot Testbed is a hierarchically distributed processing system which is linked together through a standard, commercial Ethernet. Standard Ethernet systems are primarily designed to manage non-real-time information transfer. Therefore, collisions on the net (i.e., two or more sources attempting to send data at the same time) are managed by randomly rescheduling one of the sources to retransmit at a later time interval. Although acceptable for transmitting noncritical data such as mail, this particular feature is unacceptable for real-time hierarchical command and control systems such as the Telerobot. Data transfer and scheduling simulations, such as token ring, offer solutions to collision management, but do not appropriately characterize real-time data transfer/interactions for robotic systems. Therefore, models like these do not provide a viable simulation environment for understanding real-time network loading. A real-time network loading model is being developed which allows processor-to-processor interactions to be simulated, collisions (and respective probabilities) to be logged, collision-prone areas to be identified, and network control variable adjustments to be reentered as a means of examining and reducing collision-prone regimes that occur in the process of simulating a complete task sequence.

The Latent Variable Approach as Applied to Transitive Reasoning

ERIC Educational Resources Information Center

Bouwmeester, Samantha; Vermunt, Jeroen K.; Sijtsma, Klaas

2012-01-01

We discuss the limitations of hypothesis testing using (quasi-) experiments in the study of cognitive development and suggest latent variable modeling as a viable alternative to experimentation. Latent variable models allow testing a theory as a whole, incorporating individual differences with respect to developmental processes or abilities in the…

Global sensitivity analysis of a dynamic agroecosystem model under different irrigation treatments

USDA-ARS?s Scientific Manuscript database

Savings in consumptive use through limited or deficit irrigation in agriculture has become an increasingly viable source of additional water for places with high population growth such as the Colorado Front Range, USA. Crop models provide a mechanism to evaluate various management methods without pe...

Pivotal Response Group Treatment Program for Parents of Children with Autism

ERIC Educational Resources Information Center

Minjarez, Mendy Boettcher; Williams, Sharon E.; Mercier, Emma M.; Hardan, Antonio Y.

2011-01-01

The number of children diagnosed with autism spectrum disorders is increasing, necessitating the development of efficient treatment models. Research has demonstrated that parent-delivered behavioral interventions are a viable treatment model; however, little research has focused on teaching parents in groups. The aim of this study was to…

A scalable quantum computer with ions in an array of microtraps

PubMed

Cirac; Zoller

2000-04-06

Quantum computers require the storage of quantum information in a set of two-level systems (called qubits), the processing of this information using quantum gates and a means of final readout. So far, only a few systems have been identified as potentially viable quantum computer models--accurate quantum control of the coherent evolution is required in order to realize gate operations, while at the same time decoherence must be avoided. Examples include quantum optical systems (such as those utilizing trapped ions or neutral atoms, cavity quantum electrodynamics and nuclear magnetic resonance) and solid state systems (using nuclear spins, quantum dots and Josephson junctions). The most advanced candidates are the quantum optical and nuclear magnetic resonance systems, and we expect that they will allow quantum computing with about ten qubits within the next few years. This is still far from the numbers required for useful applications: for example, the factorization of a 200-digit number requires about 3,500 qubits, rising to 100,000 if error correction is implemented. Scalability of proposed quantum computer architectures to many qubits is thus of central importance. Here we propose a model for an ion trap quantum computer that combines scalability (a feature usually associated with solid state proposals) with the advantages of quantum optical systems (in particular, quantum control and long decoherence times).

Thermoelectrics as elements of hybrid-electric vehicle thermal energy systems

NASA Astrophysics Data System (ADS)

Headings, Leon; Washington, Gregory; Jaworski, Christopher M.

2008-03-01

Despite vast technological improvements, the traditional internal combustion powered vehicle still achieves only 25- 30% efficiency, with the remainder lost primarily as heat. While the load leveling offered by hybrid-electric vehicle technology helps to improve this overall efficiency, part of the efficiency gains are achieved by making new systems such as regenerative braking viable. In a similar fashion, thermoelectric (TE) energy recovery has long been considered for traditional vehicles with mixed results, but little has been done to consider thermoelectrics in the framework of the unique energy systems of hybrid vehicles. Systems that may not have been viable or even possible with traditional vehicles may offer improvements to system efficiency as well as emissions, vehicle durability, passenger comfort, and cost. This research describes a simulation developed for evaluating and optimizing thermoelectric energy recovery systems and results for four different system configurations. Two novel system configurations are presented which offer the potential for additional benefits such as emissions reduction that will soon be quantified. In addition, a test setup is presented which was constructed for the testing and validation of various thermoelectric recovery systems. Actual test performance was near the expected theoretical performance and supported the conclusions reached from the computer simulations.

FIREFLY LUCIFERASE ATP ASSAY DEVELOPMENT FOR MONITORING BACTERIAL CONCENTRATIONS IN WATER SUPPLIES

EPA Science Inventory

This research program was initiated to develop a rapid, automatable system for measuring total viable microorganisms in potable drinking water supplies using the firefly luciferase ATP assay. The assay was adapted to an automatable flow system that provided comparable sensitivity...

Model of load balancing using reliable algorithm with multi-agent system

NASA Astrophysics Data System (ADS)

Afriansyah, M. F.; Somantri, M.; Riyadi, M. A.

2017-04-01

Massive technology development is linear with the growth of internet users which increase network traffic activity. It also increases load of the system. The usage of reliable algorithm and mobile agent in distributed load balancing is a viable solution to handle the load issue on a large-scale system. Mobile agent works to collect resource information and can migrate according to given task. We propose reliable load balancing algorithm using least time first byte (LFB) combined with information from the mobile agent. In system overview, the methodology consisted of defining identification system, specification requirements, network topology and design system infrastructure. The simulation method for simulated system was using 1800 request for 10 s from the user to the server and taking the data for analysis. Software simulation was based on Apache Jmeter by observing response time and reliability of each server and then compared it with existing method. Results of performed simulation show that the LFB method with mobile agent can perform load balancing with efficient systems to all backend server without bottleneck, low risk of server overload, and reliable.

Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.

1994-12-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lowermore » Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.« less

Effects of water-filtered infrared-A and of heat on cell death, inflammation, antioxidative potential and of free radical formation in viable skin--first results.

PubMed

Piazena, Helmut; Pittermann, Wolfgang; Müller, Werner; Jung, Katinka; Kelleher, Debra K; Herrling, Thomas; Meffert, Peter; Uebelhack, Ralf; Kietzmann, Manfred

2014-09-05

The effects of water-filtered infrared-A (wIRA) and of convective heat on viability, inflammation, inducible free radicals and antioxidative power were investigated in natural and viable skin using the ex vivo Bovine Udder System (BUS) model. Therefore, skin samples from differently treated parts of the udder of a healthy cow were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test, by prostaglandin E2 (PGE2) measurement and by electron spin resonance (ESR) spectroscopy. Neither cell viability, the inflammation status, the radical status or the antioxidative defence systems of the skin were significantly affected by wIRA applied within 30 min by using an irradiance of 1900 W m(-2) which is of relevance for clinical use, but which exceeded the maximum solar IR-A irradiance at the Earth's surface more than 5 times and which resulted in a skin surface temperature of about 45 °C without cooling and of about 37 °C with convective cooling by air ventilation. No significant effects on viability and on inflammation were detected when convective heat was applied alone under equivalent conditions in terms of the resulting skin surface temperatures and exposure time. As compared with untreated skin, free radical formation was almost doubled, whereas the antioxidative power was reduced to about 50% after convective heating to about 45 °C. Copyright © 2014 Elsevier B.V. All rights reserved.

21 CFR 173.160 - Candida guilliermondii.

Code of Federal Regulations, 2013 CFR

2013-04-01

... CONSUMPTION Enzyme Preparations and Microorganisms § 173.160 Candida guilliermondii. The food additive Candida... the following conditions: (a) The food additive is the enzyme system of the viable organism Candida...

21 CFR 173.160 - Candida guilliermondii.

Code of Federal Regulations, 2012 CFR

2012-04-01

... CONSUMPTION Enzyme Preparations and Microorganisms § 173.160 Candida guilliermondii. The food additive Candida... the following conditions: (a) The food additive is the enzyme system of the viable organism Candida...

21 CFR 173.160 - Candida guilliermondii.

Code of Federal Regulations, 2011 CFR

2011-04-01

... CONSUMPTION Enzyme Preparations and Microorganisms § 173.160 Candida guilliermondii. The food additive Candida... the following conditions: (a) The food additive is the enzyme system of the viable organism Candida...

Development and application of earth system models

PubMed Central

Prinn, Ronald G.

2013-01-01

The global environment is a complex and dynamic system. Earth system modeling is needed to help understand changes in interacting subsystems, elucidate the influence of human activities, and explore possible future changes. Integrated assessment of environment and human development is arguably the most difficult and most important “systems” problem faced. To illustrate this approach, we present results from the integrated global system model (IGSM), which consists of coupled submodels addressing economic development, atmospheric chemistry, climate dynamics, and ecosystem processes. An uncertainty analysis implies that without mitigation policies, the global average surface temperature may rise between 3.5 °C and 7.4 °C from 1981–2000 to 2091–2100 (90% confidence limits). Polar temperatures, absent policy, are projected to rise from about 6.4 °C to 14 °C (90% confidence limits). Similar analysis of four increasingly stringent climate mitigation policy cases involving stabilization of greenhouse gases at various levels indicates that the greatest effect of these policies is to lower the probability of extreme changes. The IGSM is also used to elucidate potential unintended environmental consequences of renewable energy at large scales. There are significant reasons for attention to climate adaptation in addition to climate mitigation that earth system models can help inform. These models can also be applied to evaluate whether “climate engineering” is a viable option or a dangerous diversion. We must prepare young people to address this issue: The problem of preserving a habitable planet will engage present and future generations. Scientists must improve communication if research is to inform the public and policy makers better. PMID:22706645

The neuropsychopharmacology of phencyclidine: from NMDA receptor hypofunction to the dopamine hypothesis of schizophrenia.

PubMed

Jentsch, J D; Roth, R H

1999-03-01

Administration of noncompetitive NMDA/glutamate receptor antagonists, such as phencyclidine (PCP) and ketamine, to humans induces a broad range of schizophrenic-like symptomatology, findings that have contributed to a hypoglutamatergic hypothesis of schizophrenia. Moreover, a history of experimental investigations of the effects of these drugs in animals suggests that NMDA receptor antagonists may model some behavioral symptoms of schizophrenia in nonhuman subjects. In this review, the usefulness of PCP administration as a potential animal model of schizophrenia is considered. To support the contention that NMDA receptor antagonist administration represents a viable model of schizophrenia, the behavioral and neurobiological effects of these drugs are discussed, especially with regard to differing profiles following single-dose and long-term exposure. The neurochemical effects of NMDA receptor antagonist administration are argued to support a neurobiological hypothesis of schizophrenia, which includes pathophysiology within several neurotransmitter systems, manifested in behavioral pathology. Future directions for the application of NMDA receptor antagonist models of schizophrenia to preclinical and pathophysiological research are offered.

Percolation on fitness landscapes: effects of correlation, phenotype, and incompatibilities

PubMed Central

Gravner, Janko; Pitman, Damien; Gavrilets, Sergey

2009-01-01

We study how correlations in the random fitness assignment may affect the structure of fitness landscapes, in three classes of fitness models. The first is a phenotype space in which individuals are characterized by a large number n of continuously varying traits. In a simple model of random fitness assignment, viable phenotypes are likely to form a giant connected cluster percolating throughout the phenotype space provided the viability probability is larger than 1/2n. The second model explicitly describes genotype-to-phenotype and phenotype-to-fitness maps, allows for neutrality at both phenotype and fitness levels, and results in a fitness landscape with tunable correlation length. Here, phenotypic neutrality and correlation between fitnesses can reduce the percolation threshold, and correlations at the point of phase transition between local and global are most conducive to the formation of the giant cluster. In the third class of models, particular combinations of alleles or values of phenotypic characters are “incompatible” in the sense that the resulting genotypes or phenotypes have zero fitness. This setting can be viewed as a generalization of the canonical Bateson-Dobzhansky-Muller model of speciation and is related to K- SAT problems, prominent in computer science. We analyze the conditions for the existence of viable genotypes, their number, as well as the structure and the number of connected clusters of viable genotypes. We show that analysis based on expected values can easily lead to wrong conclusions, especially when fitness correlations are strong. We focus on pairwise incompatibilities between diallelic loci, but we also address multiple alleles, complex incompatibilities, and continuous phenotype spaces. In the case of diallelic loci, the number of clusters is stochastically bounded and each cluster contains a very large sub-cube. Finally, we demonstrate that the discrete NK model shares some signature properties of models with high correlations. PMID:17692873

Multicellular Tumour Spheroid as a model for evaluation of [18F]FDG as biomarker for breast cancer treatment monitoring

PubMed Central

Monazzam, Azita; Razifar, Pasha; Simonsson, Martin; Qvarnström, Fredrik; Josephsson, Raymond; Blomqvist, Carl; Långström, Bengt; Bergström, Mats

2006-01-01

Background In order to explore a pre-clinical method to evaluate if [18F]FDG is valid for monitoring early response, we investigated the uptake of FDG in Multicellular tumour spheroids (MTS) without and with treatment with five routinely used chemotherapy agents in breast cancer. Methods The response to each anticancer treatment was evaluated by measurement of the [18F]FDG uptake and viable volume of the MTSs after 2 and 3 days of treatment. Results The effect of Paclitaxel and Docetaxel on [18F]FDG uptake per viable volume was more evident in BT474 (up to 55% decrease) than in MCF-7 (up to 25% decrease). Doxorubicin reduced the [18F]FDG uptake per viable volume more noticeable in MCF-7 (25%) than in BT474 MTSs. Tamoxifen reduced the [18F]FDG uptake per viable volume only in MCF-7 at the highest dose of 1 μM. No effect of Imatinib was observed. Conclusion MTS was shown to be appropriate to investigate the potential of FDG-PET for early breast cancer treatment monitoring; the treatment effect can be observed before any tumour size changes occur. The combination of PET radiotracers and image analysis in MTS provides a good model to evaluate the relationship between tumour volume and the uptake of metabolic tracer before and after chemotherapy. This feature could be used for screening and selecting PET-tracers for early assessment of treatment response. In addition, this new method gives a possibility to assess quickly, and in vitro, a good preclinical profile of existing and newly developed anti-cancer drugs. PMID:16556298

Experimental and Theoretical Investigation of Multispecies Oral Biofilm Resistance to Chlorhexidine Treatment

PubMed Central

Shen, Ya; Zhao, Jia; de la Fuente-Núñez, César; Wang, Zhejun; Hancock, Robert E. W.; Roberts, Clive R.; Ma, Jingzhi; Li, Jun; Haapasalo, Markus; Wang, Qi

2016-01-01

We investigate recovery of multispecies oral biofilms following chlorhexidine gluconate (CHX) and CHX with surface modifiers (CHX-Plus) treatment. Specifically, we examine the percentage of viable bacteria in the biofilms following their exposure to CHX and CHX-Plus for 1, 3, and 10 minutes, respectively. Before antimicrobial treatment, the biofilms are allowed to grow for three weeks. We find that (a). CHX-Plus kills bacteria in biofilms more effectively than the regular 2% CHX does, (b). cell continues to be killed for up to one week after exposure to the CHX solutions, (c). the biofilms start to recover after two weeks, the percentage of the viable bacteria recovers in the 1 and 3 minutes treatment groups but not in the 10 minutes treatment group after five weeks, and the biofilms fully return to the pretreatment levels after eight weeks. To understand the mechanism, a mathematical model for multiple bacterial phenotypes is developed, adopting the notion that bacterial persisters exist in the biofilms together with regulatory quorum sensing molecules and growth factor proteins. The model reveals the crucial role played by the persisters, quorum sensing molecules, and growth factors in biofilm recovery, accurately predicting the viable bacterial population after CHX treatment. PMID:27325010

A dual near-infrared and dielectric spectroscopies strategy to monitor populations of Chinese hamster ovary cells in bioreactor.

PubMed

Courtès, Franck; Ebel, Bruno; Guédon, Emmanuel; Marc, Annie

2016-05-01

to develop a new strategy combining near-infrared (NIR) and dielectric spectroscopies for real-time monitoring and in-depth characterizing populations of Chinese hamster ovary cells throughout cultures performed in bioreactors. Spectral data processing was based on off-line analyses of the cells, including trypan blue exclusion method, and lactate dehydrogenase activity (LDH). Viable cell density showed a linear correlation with permittivity up to 6 × 10(6) cells ml(-1), while a logarithmic correlation was found between non-lysed dead cell density and conductivity up to 10(7) cells ml(-1). Additionally, partial least square technique was used to develop a calibration model of the supernatant LDH activity based on online NIR spectra with a RMSEC of 55 U l(-1). Considering the LDH content of viable cells measured to be 110 U per 10(9) cells, the lysed dead cell density could be then estimated. These calibration models provided real-time prediction accuracy (R(2) ≥ 0.95) for the three types of cell populations. The high potential of a dual spectroscopy strategy to enhance the online bioprocesses characterization is demonstrated since it allows the simultaneous determination of viable, dead and lysed cell populations in real time.

Dust evolution, a global view I. Nanoparticles, nascence, nitrogen and natural selection … joining the dots

NASA Astrophysics Data System (ADS)

Jones, A. P.

2016-12-01

The role and importance of nanoparticles for interstellar chemistry and beyond is explored within the framework of The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), focusing on their active surface chemistry, the effects of nitrogen doping and the natural selection of interesting nanoparticle sub-structures. Nanoparticle-driven chemistry, and in particular the role of intrinsic epoxide-type structures, could provide a viable route to the observed gas phase OH in tenuous interstellar clouds en route to becoming molecular clouds. The aromatic-rich moieties present in asphaltenes probably provide a viable model for the structures present within aromatic-rich interstellar carbonaceous grains. The observed doping of such nanoparticle structures with nitrogen, if also prevalent in interstellar dust, could perhaps have important and observable consequences for surface chemistry and the formation of precursor pre-biotic species.

An immunologic model for rapid vaccine assessment -- a clinical trial in a test tube.

PubMed

Higbee, Russell G; Byers, Anthony M; Dhir, Vipra; Drake, Donald; Fahlenkamp, Heather G; Gangur, Jyoti; Kachurin, Anatoly; Kachurina, Olga; Leistritz, Del; Ma, Yifan; Mehta, Riyaz; Mishkin, Eric; Moser, Janice; Mosquera, Luis; Nguyen, Mike; Parkhill, Robert; Pawar, Santosh; Poisson, Louis; Sanchez-Schmitz, Guzman; Schanen, Brian; Singh, Inderpal; Song, Haifeng; Tapia, Tenekua; Warren, William; Wittman, Vaughan

2009-09-01

While the duration and size of human clinical trials may be difficult to reduce, there are several parameters in pre-clinical vaccine development that may be possible to further optimise. By increasing the accuracy of the models used for pre-clinical vaccine testing, it should be possible to increase the probability that any particular vaccine candidate will be successful in human trials. In addition, an improved model will allow the collection of increasingly more-informative data in pre-clinical tests, thus aiding the rational design and formulation of candidates entered into clinical evaluation. An acceleration and increase in sophistication of pre-clinical vaccine development will thus require the advent of more physiologically-accurate models of the human immune system, coupled with substantial advances in the mechanistic understanding of vaccine efficacy, achieved by using this model. We believe the best viable option available is to use human cells and/or tissues in a functional in vitro model of human physiology. Not only will this more accurately model human diseases, it will also eliminate any ethical, moral and scientific issues involved with use of live humans and animals. An in vitro model, termed "MIMIC" (Modular IMmune In vitro Construct), was designed and developed to reflect the human immune system in a well-based format. The MIMIC System is a laboratory-based methodology that replicates the human immune system response. It is highly automated, and can be used to simulate a clinical trial for a diverse population, without putting human subjects at risk. The MIMIC System uses the circulating immune cells of individual donors to recapitulate each individual human immune response by maintaining the autonomy of the donor. Thus, an in vitro test system has been created that is functionally equivalent to the donor's own immune system and is designed to respond in a similar manner to the in vivo response. 2009 FRAME.

Estimating golden-cheeked warbler immigration: Implications for the spatial scale of conservation

USGS Publications Warehouse

Duarte, A.; Weckerly, F.W.; Schaub, M.; Hatfield, Jeffrey S.

2016-01-01

Understanding the factors that drive population dynamics is fundamental to species conservation and management. Since the golden-cheeked warbler Setophaga chrysoparia was first listed as endangered, much effort has taken place to monitor warbler abundance, occupancy, reproduction and survival. Yet, despite being directly related to local population dynamics, movement rates have not been estimated for the species. We used an integrated population model to investigate the relationship between immigration rate, fledging rate, survival probabilities and population growth rate for warblers in central Texas, USA. Furthermore, using a deterministic projection model, we examined the response required by vital rates to maintain a viable population across varying levels of immigration. Warbler abundance fluctuated with an overall positive trend across years. In the absence of immigration, the abundance would have decreased. However, the population could remain viable without immigration if both adult and juvenile survival increased by almost half or if juvenile survival more than doubled. We also investigated the response required by fledging rates across a range of immigration in order to maintain a viable population. Overall, we found that immigration was required to maintain warbler target populations, indicating that warbler conservation and management programs need to be implemented at larger spatial scales than current efforts to be effective. This study also demonstrates that by using limited data within integrated population models, biologists are able to monitor multiple key demographic parameters simultaneously to gauge the efficacy of strategies designed to maximize warbler viability in a changing landscape.

Norfloxacin is more effective than Rifaximin in avoiding bacterial translocation in an animal model of cirrhosis.

PubMed

Gómez-Hurtado, Isabel; Gimenez, Paula; García, Irma; Zapater, Pedro; Francés, Rubén; González-Navajas, José M; Manichanh, Chaysavanh; Ramos, José M; Bellot, Pablo; Guarner, Francisco; Such, José

2018-02-01

Norfloxacin administration is useful in preventing bacterial infections in cirrhosis but associated to the generation of resistant species. Rifaximin is known to reach high concentrations in the intestinal lumen without generating relevant resistance in the intestinal flora. Our aim was to compare the effect of Norfloxacin and Rifaximin on intestinal flora composition, bacterial translocation and survival in cirrhotic rats. Cirrhosis was induced in rats by oral administration of CCl 4 . Animals were divided into three groups: only CCl 4 (group I, n = 10); CCl 4 + Norfloxacin (group II, n = 17) and CCl 4 + Rifaximin (group III, n = 14). Gut bacterial composition, bacterial translocation and cytokine levels were measured. Forty-one rats were finally included. The incidence of viable and non-viable bacterial translocation was significantly reduced in animals receiving Norfloxacin; Rifaximin also decreased the incidence of viable and non-viable bacterial translocation, but did not reach statistical significance. Serum TNF-α levels were significantly lower in antibiotic groups. Norfloxacin modified intestinal microbiota, depleting significantly more pathobionts than Rifaximin. Norfloxacin is more effective than Rifaximin in preventing bacterial translocation in rats with cirrhosis probably because of its capacity to reduce pathobionts from intestinal microbiota. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

CHZ868, a Type II JAK2 Inhibitor, Reverses Type I JAK Inhibitor Persistence and Demonstrates Efficacy in Myeloproliferative Neoplasms

PubMed Central

Meyer, Sara C.; Keller, Matthew D.; Chiu, Sophia; Koppikar, Priya; Guryanova, Olga A.; Rapaport, Franck; Xu, Ke; Manova, Katia; Pankov, Dmitry; O’Reilly, Richard J.; Kleppe, Maria; McKenney, Anna Sophia; Shih, Alan H.; Shank, Kaitlyn; Ahn, Jihae; Papalexi, Eftymia; Spitzer, Barbara; Socci, Nick; Viale, Agnes; Mandon, Emeline; Ebel, Nicolas; Andraos, Rita; Rubert, Joëlle; Dammassa, Ernesta; Romanet, Vincent; Dölemeyer, Arno; Zender, Michael; Heinlein, Melanie; Rampal, Rajit; Weinberg, Rona Singer; Hoffman, Ron; Sellers, William R.; Hofmann, Francesco; Murakami, Masato; Baffert, Fabienne; Gaul, Christoph; Radimerski, Thomas; Levine, Ross L.

2015-01-01

Summary Although clinically tested JAK inhibitors reduce splenomegaly and systemic symptoms, molecular responses are not observed in most myeloproliferative neoplasms (MPN) patients. We previously demonstrated that MPN cells become persistent to type I JAK inhibitors that bind the active conformation of JAK2. We investigated if CHZ868, a type II JAK inhibitor, would demonstrate activity in JAK inhibitor persistent cells, murine MPN models, and MPN patient samples. JAK2- and MPL-mutant cell lines were sensitive to CHZ868, including type I JAK inhibitor persistent cells. CHZ868 showed significant activity in murine MPN models and induced reductions in mutant allele burden not observed with type I JAK inhibitors. These data demonstrate that type II JAK inhibition is a viable therapeutic approach for MPN patients. PMID:26175413

Infectious diseases: Surveillance, genetic modification and simulation

USGS Publications Warehouse

Koh, H. L.; Teh, S.Y.; De Angelis, D. L.; Jiang, J.

2011-01-01

Infectious diseases such as influenza and dengue have the potential of becoming a worldwide pandemic that may exert immense pressures on existing medical infrastructures. Careful surveillance of these diseases, supported by consistent model simulations, provides a means for tracking the disease evolution. The integrated surveillance and simulation program is essential in devising effective early warning systems and in implementing efficient emergency preparedness and control measures. This paper presents a summary of simulation analysis on influenza A (H1N1) 2009 in Malaysia. This simulation analysis provides insightful lessons regarding how disease surveillance and simulation should be performed in the future. This paper briefly discusses the controversy over the experimental field release of genetically modified (GM) Aedes aegypti mosquito in Malaysia. Model simulations indicate that the proposed release of GM mosquitoes is neither a viable nor a sustainable control strategy. ?? 2011 WIT Press.

Flavoured Dark Matter moving left

NASA Astrophysics Data System (ADS)

Blanke, Monika; Das, Satrajit; Kast, Simon

2018-02-01

We investigate the phenomenology of a simplified model of flavoured Dark Matter (DM), with a dark fermionic flavour triplet coupling to the left-handed SU(2) L quark doublets via a scalar mediator. The DM-quark coupling matrix is assumed to constitute the only new source of flavour and CP violation, following the hypothesis of Dark Minimal Flavour Violation. We analyse the constraints from LHC searches, from meson mixing data in the K, D, and B d,s meson systems, from thermal DM freeze-out, and from direct detection experiments. Our combined analysis shows that while the experimental constraints are similar to the DMFV models with DM coupling to right-handed quarks, the multitude of couplings between DM and the SM quark sector resulting from the SU(2) L structure implies a richer phenomenology and significantly alters the resulting impact on the viable parameter space.

A viable method and configuration for fermenting biomass sugars to ethanol using native Saccharomyces cerevisiae.

PubMed

Yuan, Dawei; Rao, Kripa; Varanasi, Sasidhar; Relue, Patricia

2012-08-01

A system that incorporates a packed bed reactor for isomerization of xylose and a hollow fiber membrane fermentor (HFMF) for sugar fermentation by yeast was developed for facile recovery of the xylose isomerase enzyme pellets and reuse of the cartridge loaded with yeast. Fermentation of pre-isomerized poplar hydrolysate produced using ionic liquid pretreatment in HFMF resulted in ethanol yields equivalent to that of model sugar mixtures of xylose and glucose. By recirculating model sugar mixtures containing partially isomerized xylose through the packed bed and the HFMF connected in series, 39 g/l ethanol was produced within 10h with 86.4% xylose utilization. The modular nature of this configuration has the potential for easy scale-up of the simultaneous isomerization and fermentation process without significant capital costs. Copyright © 2012 Elsevier Ltd. All rights reserved.

Determination of Ancylostoma caninum ova viability using metabolic profiling.

PubMed

Gyawali, P; Beale, D J; Ahmed, W; Karpe, A V; Magalhaes, R J Soares; Morrison, P D; Palombo, E A

2016-09-01

Differentiation between viable and non-viable hookworm ova in environmental samples is necessary in order to implement strategies to mitigate re-infections in endemic regions. In this study, an untargeted metabolic profiling method was developed that utilised gas chromatography-mass spectrometry (GC-MS) in order to investigate hookworm ova viability. Ancylostoma caninum was used to investigate the metabolites within viable and non-viable ova. Univariate and multivariate statistical analyses of the data resulted in the identification of 53 significant metabolites across all hookworm ova samples. The major compounds observed in viable and non-viable hookworm ova were tetradecanoic acid, commonly known as myristic acid [fold change (FC) = 0.4], and dodecanoic acid, commonly known as lauric acid (FC = 0.388). Additionally, the viable ova had self-protecting metabolites such as prostaglandins, a typical feature absent in non-viable ova. The results of this study demonstrate that metabolic profiling using GC-MS methods can be used to determine the viability of canine hookworm ova. Further studies are needed to assess the applicability of metabolic profiling using GC-MS to detect viable hookworm ova in the mixed (viable and non-viable) populations from environmental samples and identify the metabolites specific to human hookworm species.

Transvaginal ultrasound in threatened abortions with empty gestational sacs.

PubMed

Tongsong, T; Wanapirak, C; Srisomboon, J; Sirichotiyakul, S; Polsrisuthikul, T; Pongsatha, S

1994-09-01

To determine whether transvaginal ultrasound criteria alone can distinguish viable from non-viable gestational sacs at a single examination. A prospective descriptive study was undertaken and analysis performed on 211 pregnancies complicated by threatened abortion and empty gestation sacs diagnosed by transvaginal ultrasound. The main outcome measure was the final diagnosis of viable or non-viable gestation on subsequent transvaginal sonography. The study shows that a single transvaginal ultrasound examination is useful in differentiating viable from non-viable gestation sacs. The mean sac diameter (MSD) was found to be the most useful criterion for determining non-viability. An MSD of > or = 17 mm that lacked an embryo and an MSD of > or = 13 mm without visible yolk sac were reliable predictors of non-viable gestation sacs at a single examination with 100% specificity and 100% positive predictive value. An MSD > or = 13 mm without visible yolk sac was the most sensitive criterion. Using MSD criteria, 73% of non-viable gestations could be reliably identified without any false-positive diagnoses. Deformed shape, low position and thin decidual reaction are strong indicators of non-viable gestations but are not 100% accurate. There is still a significant proportion of empty sacs, where no accurate distinction between viable and non-viable can be made according to one criterion at a single examination and in these cases serial examinations should be carried out before any active management is advocated. In most cases, transvaginal sonographic criteria alone can distinguish viable from non-viable empty gestational sacs at a single examination.

Nondestructive detection of total viable count changes of chilled pork in high oxygen storage condition based on hyperspectral technology

NASA Astrophysics Data System (ADS)

Zheng, Xiaochun; Peng, Yankun; Li, Yongyu; Chao, Kuanglin; Qin, Jianwei

2017-05-01

The plate count method is commonly used to detect the total viable count (TVC) of bacteria in pork, which is timeconsuming and destructive. It has also been used to study the changes of the TVC in pork under different storage conditions. In recent years, many scholars have explored the non-destructive methods on detecting TVC by using visible near infrared (VIS/NIR) technology and hyperspectral technology. The TVC in chilled pork was monitored under high oxygen condition in this study by using hyperspectral technology in order to evaluate the changes of total bacterial count during storage, and then evaluate advantages and disadvantages of the storage condition. The VIS/NIR hyperspectral images of samples stored in high oxygen condition was acquired by a hyperspectral system in range of 400 1100nm. The actual reference value of total bacteria was measured by standard plate count method, and the results were obtained in 48 hours. The reflection spectra of the samples are extracted and used for the establishment of prediction model for TVC. The spectral preprocessing methods of standard normal variate transformation (SNV), multiple scatter correction (MSC) and derivation was conducted to the original reflectance spectra of samples. Partial least squares regression (PLSR) of TVC was performed and optimized to be the prediction model. The results show that the near infrared hyperspectral technology based on 400-1100nm combined with PLSR model can describe the growth pattern of the total bacteria count of the chilled pork under the condition of high oxygen very vividly and rapidly. The results obtained in this study demonstrate that the nondestructive method of TVC based on NIR hyperspectral has great potential in monitoring of edible safety in processing and storage of meat.

Oxygen supply for CHO cells immobilized on a packed-bed of Fibra-Cel disks.

PubMed

Meuwly, F; Loviat, F; Ruffieux, P-A; Bernard, A R; Kadouri, A; von Stockar, U

2006-03-05

Packed-bed bioreactors (PBR) have proven to be efficient systems to culture mammalian cells at very high cell density in perfusion mode, thus leading to very high volumetric productivity. However, the immobilized cells must be continuously supplied with all nutrients in sufficient quantities to remain viable and productive over the full duration of the perfusion culture. Among all nutrients, oxygen is the most critical since it is present at very low concentration due to its low solubility in cell culture medium. This work presents the development of a model for oxygenation in a packed-bed bioreactor system. The experimental system used to develop the model was a packed-bed of Fibra-Cel disk carriers used to cultivate Chinese Hamster Ovary cells at high density ( approximately 6.1 x 10(7) cell/mL) in perfusion mode. With the help of this model, it was possible to identify if a PBR system is operated in optimal or sub-optimal conditions. Using the model, two options were proposed, which could improve the performance of the basal system by about twofold, that is, by increasing the density of immobilized cells per carrier volume from 6.1 x 10(7) to 1.2 x 10(8) cell/mL, or by increasing the packed-bed height from 0.2 to 0.4 m. Both strategies would be rather simple to test and implement in the packed-bed bioreactor system used for this study. As a result, it would be possible to achieve a substantial improvement of about twofold higher productivity as compared with the basal conditions.

Survival of genetically modified and self-cloned strains of commercial baker's yeast in simulated natural environments: environmental risk assessment.

PubMed

Ando, Akira; Suzuki, Chise; Shima, Jun

2005-11-01

Although genetic engineering techniques for baker's yeast might improve the yeast's fermentation characteristics, the lack of scientific data on the survival of such strains in natural environments as well as the effects on human health prevent their commercial use. Disruption of acid trehalase gene (ATH1) improves freeze tolerance, which is a crucial characteristic in frozen-dough baking. In this study, ATH1 disruptants constructed by genetic modification (GM) and self-cloning (SC) techniques were used as models to study such effects because these strains have higher freeze tolerance and are expected to be used commercially. Behavior of the strains in simulated natural environments, namely, in soil and water, was studied by measuring the change in the number of viable cells and in the concentration of DNA that contains ATH1 loci. Measurements were made using a real-time PCR method during 40 days of cultivation. Results showed that the number of viable cells of GM and SC strains decreased in a time-dependent manner and that the decrease rate was nearly equal to or higher than that for wild-type (WT) yeast. For all three strains (SC, GM, and WT) in the two simulated natural environments (water and soil), the DNA remained longer than did viable cells but the decrease patterns of either the DNA or the viable cells of SC and GM strains had tendencies similar to those of the WT strain. In conclusion, disruption of ATH1 by genetic engineering apparently does not promote the survival of viable cells and DNA in natural environments.

The development of a model of creative space and its potential for transfer from non-formal to formal education

NASA Astrophysics Data System (ADS)

White, Irene; Lorenzi, Francesca

2016-12-01

Creativity has been emerging as a key concept in educational policies since the mid-1990s, with many Western countries restructuring their education systems to embrace innovative approaches likely to stimulate creative and critical thinking. But despite current intentions of putting more emphasis on creativity in education policies worldwide, there is still a relative dearth of viable models which capture the complexity of creativity and the conditions for its successful infusion into formal school environments. The push for creativity is in direct conflict with the results-driven/competitive performance-oriented culture which continues to dominate formal education systems. The authors of this article argue that incorporating creativity into mainstream education is a complex task and is best tackled by taking a systematic and multifaceted approach. They present a multidimensional model designed to help educators in tackling the challenges of the promotion of creativity. Their model encompasses three distinct yet interrelated dimensions of a creative space - physical, social-emotional and critical. The authors use the metaphor of space to refer to the interplay of the three identified dimensions. Drawing on confluence approaches to the theorisation of creativity, this paper exemplifies the development of a model before the background of a growing trend of systems theories. The aim of the model is to be helpful in systematising creativity by offering parameters - derived from the evaluation of an example offered by a non-formal educational environment - for the development of creative environments within mainstream secondary schools.

Graceful Failure and Societal Resilience Analysis Via Agent-Based Modeling and Simulation

NASA Astrophysics Data System (ADS)

Schopf, P. S.; Cioffi-Revilla, C.; Rogers, J. D.; Bassett, J.; Hailegiorgis, A. B.

2014-12-01

Agent-based social modeling is opening up new methodologies for the study of societal response to weather and climate hazards, and providing measures of resiliency that can be studied in many contexts, particularly in coupled human and natural-technological systems (CHANTS). Since CHANTS are complex adaptive systems, societal resiliency may or may not occur, depending on dynamics that lack closed form solutions. Agent-based modeling has been shown to provide a viable theoretical and methodological approach for analyzing and understanding disasters and societal resiliency in CHANTS. Our approach advances the science of societal resilience through computational modeling and simulation methods that complement earlier statistical and mathematical approaches. We present three case studies of social dynamics modeling that demonstrate the use of these agent based models. In Central Asia, we exmaine mutltiple ensemble simulations with varying climate statistics to see how droughts and zuds affect populations, transmission of wealth across generations, and the overall structure of the social system. In Eastern Africa, we explore how successive episodes of drought events affect the adaptive capacity of rural households. Human displacement, mainly, rural to urban migration, and livelihood transition particularly from pastoral to farming are observed as rural households interacting dynamically with the biophysical environment and continually adjust their behavior to accommodate changes in climate. In the far north case we demonstrate one of the first successful attempts to model the complete climate-permafrost-infrastructure-societal interaction network as a complex adaptive system/CHANTS implemented as a ``federated'' agent-based model using evolutionary computation. Analysis of population changes resulting from extreme weather across these and other cases provides evidence for the emergence of new steady states and shifting patterns of resilience.

Luminescent solar concentrators utilizing stimulated emission.

PubMed

Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

2016-03-21

Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power.

A plasmid-based reporter system for live cell imaging of dengue virus infected cells.

PubMed

Medin, Carey L; Valois, Sierra; Patkar, Chinmay G; Rothman, Alan L

2015-01-01

Cell culture models are used widely to study the effects of dengue virus (DENV) on host cell function. Current methods of identification of cells infected with an unmodified DENV requires fixation and permeablization of cells to allow DENV-specific antibody staining. This method does not permit imaging of viable cells over time. In this report, a plasmid-based reporter was developed to allow non-destructive identification of DENV-infected cells. The plasmid-based reporter was demonstrated to be broadly applicable to the four DENV serotypes, including low-passaged strains, and was specifically cleaved by the viral protease with minimal interference on viral production. This study reveals the potential for this novel reporter system to advance the studies of virus-host interactions during DENV infection. Copyright © 2014 Elsevier B.V. All rights reserved.

Planet formation

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.

1993-01-01

Models of planetary formation are developed using the present single example of a planetary system, supplemented by limited astrophysical observations of star-forming regions and circumstellar disks. The solar nebula theory and the planetesimal hypothesis are discussed. The latter is found to provide a viable theory of the growth of the terrestrial planets, the cores of the giant planets, and the smaller bodies present in the solar system. The formation of solid bodies of planetary size should be a common event, at least around young stars which do not have binary companions orbiting at planetary distances. Stochastic impacts of large bodies provide sufficient angular momentum to produce the obliquities of the planets. The masses and bulk compositions of the planets can be understood in a gross sense as resulting from planetary growth within a disk whose temperature and surface density decreased with distance from the growing sun.

Validation of microinjection methods for generating knockout mice by CRISPR/Cas-mediated genome engineering.

PubMed

Horii, Takuro; Arai, Yuji; Yamazaki, Miho; Morita, Sumiyo; Kimura, Mika; Itoh, Masahiro; Abe, Yumiko; Hatada, Izuho

2014-03-28

The CRISPR/Cas system, in which the Cas9 endonuclease and a guide RNA complementary to the target are sufficient for RNA-guided cleavage of the target DNA, is a powerful new approach recently developed for targeted gene disruption in various animal models. However, there is little verification of microinjection methods for generating knockout mice using this approach. Here, we report the verification of microinjection methods of the CRISPR/Cas system. We compared three methods for injection: (1) injection of DNA into the pronucleus, (2) injection of RNA into the pronucleus, and (3) injection of RNA into the cytoplasm. We found that injection of RNA into the cytoplasm was the most efficient method in terms of the numbers of viable blastocyst stage embryos and full-term pups generated. This method also showed the best overall knockout efficiency.

Towards a Quantum Theory of Humour

NASA Astrophysics Data System (ADS)

Gabora, Liane; Kitto, Kirsty

2016-12-01

This paper proposes that cognitive humour can be modelled using the mathematical framework of quantum theory, suggesting that a Quantum Theory of Humour (QTH) is a viable approach. We begin with brief overviews of both research on humour, and the generalized quantum framework. We show how the bisociation of incongruous frames or word meanings in jokes can be modelled as a linear superposition of a set of basis states, or possible interpretations, in a complex Hilbert space. The choice of possible interpretations depends on the context provided by the set-up versus the punchline of a joke. We apply QTH first to a verbal pun, and then consider how this might be extended to frame blending in cartoons. An initial study of 85 participant responses to 35 jokes (and a number of variants) suggests that there is reason to believe that a quantum approach to the modelling of cognitive humour is a viable new avenue of research for the field of quantum cognition.

Abe Silverstein 10- by 10-Foot Supersonic Wind Tunnel Validated for Low-Speed (Subsonic) Operation

NASA Technical Reports Server (NTRS)

Hoffman, Thomas R.

2001-01-01

The NASA Glenn Research Center and Lockheed Martin Corporation tested an aircraft model in two wind tunnels to compare low-speed (subsonic) flow characteristics. Objectives of the test were to determine and document the similarities and uniqueness of the tunnels and to validate that Glenn's 10- by 10-Foot Supersonic Wind Tunnel (10x10 SWT) is a viable low-speed test facility. Results from two of Glenn's wind tunnels compare very favorably and show that the 10x10 SWT is a viable low-speed wind tunnel. The Subsonic Comparison Test was a joint effort by NASA and Lockheed Martin using the Lockheed Martin's Joint Strike Fighter Concept Demonstration Aircraft model. Although Glenn's 10310 and 836 SWT's have many similarities, they also have unique characteristics. Therefore, test data were collected for multiple model configurations at various vertical locations in the test section, starting at the test section centerline and extending into the ceiling and floor boundary layers.

Characterisation of coral explants: a model organism for cnidarian-dinoflagellate studies

NASA Astrophysics Data System (ADS)

Gardner, S. G.; Nielsen, D. A.; Petrou, K.; Larkum, A. W. D.; Ralph, P. J.

2015-03-01

Coral cell cultures made from reef-building scleractinian corals have the potential to aid in the pursuit of understanding of the cnidarian-dinoflagellate symbiosis. Various methods have previously been described for the production of cell cultures in vitro with a range of success and longevity. In this study, viable tissue spheroids containing host tissue and symbionts (coral explants) were grown from the tissues of Fungia granulosa. The cultured explants remained viable for over 2 months and showed morphological similarities in tissue structure and internal microenvironment to reef-building scleractinian corals. The photophysiology of the explants (1 week old) closely matched that of the parent coral F. granulosa. This study provides the first empirical basis for supporting the use of coral explants as laboratory models for studying coral symbioses. In particular, it highlights how these small, self-sustaining, skeleton-free models can be useful for a number of molecular, genetic and physiological analyses necessary for investigating host-symbiont interactions at the microscale.

Predicting network modules of cell cycle regulators using relative protein abundance statistics.

PubMed

Oguz, Cihan; Watson, Layne T; Baumann, William T; Tyson, John J

2017-02-28

Parameter estimation in systems biology is typically done by enforcing experimental observations through an objective function as the parameter space of a model is explored by numerical simulations. Past studies have shown that one usually finds a set of "feasible" parameter vectors that fit the available experimental data equally well, and that these alternative vectors can make different predictions under novel experimental conditions. In this study, we characterize the feasible region of a complex model of the budding yeast cell cycle under a large set of discrete experimental constraints in order to test whether the statistical features of relative protein abundance predictions are influenced by the topology of the cell cycle regulatory network. Using differential evolution, we generate an ensemble of feasible parameter vectors that reproduce the phenotypes (viable or inviable) of wild-type yeast cells and 110 mutant strains. We use this ensemble to predict the phenotypes of 129 mutant strains for which experimental data is not available. We identify 86 novel mutants that are predicted to be viable and then rank the cell cycle proteins in terms of their contributions to cumulative variability of relative protein abundance predictions. Proteins involved in "regulation of cell size" and "regulation of G1/S transition" contribute most to predictive variability, whereas proteins involved in "positive regulation of transcription involved in exit from mitosis," "mitotic spindle assembly checkpoint" and "negative regulation of cyclin-dependent protein kinase by cyclin degradation" contribute the least. These results suggest that the statistics of these predictions may be generating patterns specific to individual network modules (START, S/G2/M, and EXIT). To test this hypothesis, we develop random forest models for predicting the network modules of cell cycle regulators using relative abundance statistics as model inputs. Predictive performance is assessed by the areas under receiver operating characteristics curves (AUC). Our models generate an AUC range of 0.83-0.87 as opposed to randomized models with AUC values around 0.50. By using differential evolution and random forest modeling, we show that the model prediction statistics generate distinct network module-specific patterns within the cell cycle network.

Defense Systems Modernization and Sustainment Initiative

DTIC Science & Technology

2014-03-31

research programs focus on sustainable production, sustainable energy, sustainable mobility , and ecologically friendly information technology systems...for Sustainable Mobility (CSM): focused on developing viable technologies for sustainable transportation systems and the support of complex equipment...utilization of mobile devices. The objective of the evaluation was to identify features that the new implementation of LEEDS would require, such as

Field-based estimates of global warming potential in bioenergy systems of Hawaii: Crop choice and deficit irrigation

USDA-ARS?s Scientific Manuscript database

Replacing fossil fuel with biofuel is environmentally viable only if the net greenhouse gas (GHG) footprint of the system is reduced. The effects of replacing annual arable crops with perennial bioenergy feedstocks on net GHG production and soil carbon (C) stock are critical to the system-level bal...

The effects of feeding monensin on rumen microbial communities and methanogenesis in bred heifers fed in a drylot

USDA-ARS?s Scientific Manuscript database

Drylot beef cow-calf systems are viable alternative management systems to traditional forage-based systems. In such confinement, adding ionophores such as monensin to the diets of beef cattle is common, and has been shown to improve feed efficiency and increase average daily gain. The addition of mo...

Modelling the impacts of pests and diseases on agricultural systems.

PubMed

Donatelli, M; Magarey, R D; Bregaglio, S; Willocquet, L; Whish, J P M; Savary, S

2017-07-01

The improvement and application of pest and disease models to analyse and predict yield losses including those due to climate change is still a challenge for the scientific community. Applied modelling of crop diseases and pests has mostly targeted the development of support capabilities to schedule scouting or pesticide applications. There is a need for research to both broaden the scope and evaluate the capabilities of pest and disease models. Key research questions not only involve the assessment of the potential effects of climate change on known pathosystems, but also on new pathogens which could alter the (still incompletely documented) impacts of pests and diseases on agricultural systems. Yield loss data collected in various current environments may no longer represent a adequate reference to develop tactical, decision-oriented, models for plant diseases and pests and their impacts, because of the ongoing changes in climate patterns. Process-based agricultural simulation modelling, on the other hand, appears to represent a viable methodology to estimate the impacts of these potential effects. A new generation of tools based on state-of-the-art knowledge and technologies is needed to allow systems analysis including key processes and their dynamics over appropriate suitable range of environmental variables. This paper offers a brief overview of the current state of development in coupling pest and disease models to crop models, and discusses technical and scientific challenges. We propose a five-stage roadmap to improve the simulation of the impacts caused by plant diseases and pests; i) improve the quality and availability of data for model inputs; ii) improve the quality and availability of data for model evaluation; iii) improve the integration with crop models; iv) improve the processes for model evaluation; and v) develop a community of plant pest and disease modelers.

Experimental Testing and Modeling of a Pneumatic Regolith Delivery System for ISRU

NASA Technical Reports Server (NTRS)

Santiago-Maldonado, Edgardo; Dominquez, Jesus A.; Mantovani, James G.

2011-01-01

Excavating and transporting planetary regolith are examples of surface activities that may occur during a future space exploration mission to a planetary body. Regolith, whether it is collected on the Moon, Mars or even an asteroid, consists of granular minerals, some of which have been identified to be viable resources that can be mined and processed chemically to extract useful by-products, such as oxygen, water, and various metals and metal alloys. Even the depleted "waste" material from such chemical processes may be utilized later in the construction of landing pads and protective structures at the site of a planetary base. One reason for excavating and conveying planetary regolith is to deliver raw regolith material to in-situ resource utilization (ISRU) systems. The goal of ISRU is to provide expendable supplies and materials at the planetary destination, if possible. An in-situ capability of producing mission-critical substances such as oxygen will help to extend the mission and its success, and will greatly lower the overall cost of a mission by either eliminating, or significantly reducing, the need to transport the same expendable materials from the Earth. In order to support the goals and objectives of present and future ISRU projects, NASA seeks technology advancements in the areas of regolith conveying. Such systems must be effective, efficient and provide reliable performance over long durations while being exposed to the harsh environments found on planetary surfaces. These conditions include contact with very abrasive regolith particulates, exposure to high vacuum or dry (partial) atmospheres, wide variations in temperature, reduced gravity, and exposure to space radiation. Regolith conveying techniques that combine reduced failure modes and low energy consumption with high material transfer rates will provide significant value for future space exploration missions to the surfaces of the moon, Mars and asteroids. Pneumatic regolith conveying has demonstrated itself to be a viable delivery system through testing under terrestrial and reduced gravity conditions in recent years. Modeling and experimental testing have been conducted at NASA Kennedy Space Center to study and advance pneumatic planetary regolith delivery systems in support of NASA's ISRU project. The goal of this work is to use the model to predict solid-gas flow patterns in reduced gravity environments for ISRU inlet gas line allowing the eductor inlet gas flow to vary and depend on the flow pattern developed at the eductor as inferred by the experimental observations.

123I-IPPA SPECT for the prediction of enhanced left ventricular function after coronary bypass graft surgery. Multicenter IPPA Viability Trial Investigators. 123I-iodophenylpentadecanoic acid.

PubMed

Verani, M S; Taillefer, R; Iskandrian, A E; Mahmarian, J J; He, Z X; Orlandi, C

2000-08-01

Fatty acids are the prime metabolic substrate for myocardial energy production. Hence, fatty acid imaging may be useful in the assessment of myocardial hibernation. The goal of this prospective, multicenter trial was to assess the use of a fatty acid, 123I-iodophenylpentadecanoic acid (IPPA), to identify viable, hibernating myocardium. Patients (n = 119) with abnormal left ventricular wall motion and a left ventricular ejection fraction (LVEF) < 40% who were already scheduled to undergo coronary artery bypass grafting (CABG) underwent IPPA tomography (rest and 30-min redistribution) and blood-pool radionuclide angiography within 3 d of the scheduled operation. Radionuclide angiography was repeated 6-8 wk after CABG. The study endpoint was a > or =10% increase in LVEF after CABG. The number of IPPA-viable abnormally contracting segments necessary to predict a positive LVEF outcome was determined by receiver operating characteristic (ROC) curves and was included in a logistic regression analysis, together with selected clinical variables. Before CABG, abnormal IPPA tomography findings were seen in 113 of 119 patients (95%), of whom 71 (60%) had redistribution in the 30-min images. The LVEF increased modestly after CABG (from 32% +/- 12% to 36% +/- 8%, P< 0.001).A > or =10% increase in LVEF after CABG occurred in 27 of 119 patients (23%). By ROC curves, the best predictor of a > or =10% increase in LVEF was the presence of > or =7 IPPA-viable segments (accuracy, 72%; confidence interval, 64%-80%). Among clinical and scintigraphic variables, the single most important predictor also was the number of IPPA-viable segments (P = 0.008). The number of IPPA-viable segments added significant incremental value to the best clinical predictor model. Asubstantial increase in LVEF occurs after CABG in only a minority of patients (23%) with depressed preoperative function. The number of IPPA-viable segments is useful in predicting a clinically meaningful increase in LVEF.

Analysis of parameter sensitivity and identifiability of root zone water quality model (RZWQM) for dryland sugerbeet modeling

USDA-ARS?s Scientific Manuscript database

Sugarbeet is being considered as one of the most viable feedstock alternatives to corn for biofuel production since herbicide resistant energy beets were deregulated by USDA in 2012. Growing sugarbeets for biofuel production may have significant impacts on soil health and water quality in the north-...

Increasing Independence in Children with Autism Spectrum Disorders Using Video Self Modeling

ERIC Educational Resources Information Center

Bucalos, Julie Iberer

2013-01-01

Independent task completion was examined using a multiple probe across participants research design for three students with autism spectrum disorders (ASD) functioning in an inclusive classroom. Results were positive and suggest that video self-modeling (VSM) is a viable solution to decrease prompt dependence and increase independence and task…

An Empirical Generative Framework for Computational Modeling of Language Acquisition

ERIC Educational Resources Information Center

Waterfall, Heidi R.; Sandbank, Ben; Onnis, Luca; Edelman, Shimon

2010-01-01

This paper reports progress in developing a computer model of language acquisition in the form of (1) a generative grammar that is (2) algorithmically learnable from realistic corpus data, (3) viable in its large-scale quantitative performance and (4) psychologically real. First, we describe new algorithmic methods for unsupervised learning of…

An Effective Model for Enhancing Underrepresented Minority Participation and Success in Geoscience Undergraduate Research

ERIC Educational Resources Information Center

Blake, Reginald A.; Liou-Mark, Janet; Chukuigwe, Chinedu

2013-01-01

Geoscience research is a fundamental portal through which geoscience knowledge may be acquired and disseminated. A viable model to introduce, stimulate, and prolong geoscience education has been designed and implemented at the New York City College of Technology through a National Science Foundation (NSF) Research Experiences for Undergraduates…

Developing Statistical Knowledge for Teaching during Design-Based Research

ERIC Educational Resources Information Center

Groth, Randall E.

2017-01-01

Statistical knowledge for teaching is not precisely equivalent to statistics subject matter knowledge. Teachers must know how to make statistics understandable to others as well as understand the subject matter themselves. This dual demand on teachers calls for the development of viable teacher education models. This paper offers one such model,…

Valuation of financial models with non-linear state spaces

NASA Astrophysics Data System (ADS)

Webber, Nick

2001-02-01

A common assumption in valuation models for derivative securities is that the underlying state variables take values in a linear state space. We discuss numerical implementation issues in an interest rate model with a simple non-linear state space, formulating and comparing Monte Carlo, finite difference and lattice numerical solution methods. We conclude that, at least in low dimensional spaces, non-linear interest rate models may be viable.

Natural treatment system models for wastewater management: a study from Hyderabad, India.

PubMed

Sonkamble, Sahebrao; Wajihuddin, Md; Jampani, Mahesh; Sarah, S; Somvanshi, V K; Ahmed, Shakeel; Amerasinghe, Priyanie; Boisson, Alexandre

2018-01-01

Wastewater generated on a global scale has become a significant source of water resources which necessitates appropriate management strategies. However, the complexities associated with wastewater are lack of economically viable treatment systems, especially in low- and middle-income countries. While many types of treatment systems are needed to serve the various local issues, we propose natural treatment systems (NTS) such as natural wetlands that are eco-friendly, cost-effective, and can be jointly driven by public bodies and communities. In order for it to be part of wastewater management, this study explores the NTS potential for removal of pollutants, cost-effectiveness, and reuse options for the 1.20 million m 3 /day of wastewater generated in Hyderabad, India. The pilot study includes hydro-geophysical characterization of natural wetland to determine pollutant removal efficiency and its effective utilization for treated wastewater in the peri-urban habitat. The results show the removal of organic content (76-78%), nutrients (77-97%), and microbes (99.5-99.9%) from the wetland-treated wastewater and its suitability for agriculture applications. Furthermore, the wetland efficiency integrated with engineered interventions led to the development of NTS models with different application scenarios: (i) constructed wetlands, (ii) minimized community wetlands, and (iii) single outlet system, suitable for urban, peri-urban and rural areas, respectively.

A parallel computing engine for a class of time critical processes.

PubMed

Nabhan, T M; Zomaya, A Y

1997-01-01

This paper focuses on the efficient parallel implementation of systems of numerically intensive nature over loosely coupled multiprocessor architectures. These analytical models are of significant importance to many real-time systems that have to meet severe time constants. A parallel computing engine (PCE) has been developed in this work for the efficient simplification and the near optimal scheduling of numerical models over the different cooperating processors of the parallel computer. First, the analytical system is efficiently coded in its general form. The model is then simplified by using any available information (e.g., constant parameters). A task graph representing the interconnections among the different components (or equations) is generated. The graph can then be compressed to control the computation/communication requirements. The task scheduler employs a graph-based iterative scheme, based on the simulated annealing algorithm, to map the vertices of the task graph onto a Multiple-Instruction-stream Multiple-Data-stream (MIMD) type of architecture. The algorithm uses a nonanalytical cost function that properly considers the computation capability of the processors, the network topology, the communication time, and congestion possibilities. Moreover, the proposed technique is simple, flexible, and computationally viable. The efficiency of the algorithm is demonstrated by two case studies with good results.

Emergent properties of interacting populations of spiking neurons.

PubMed

Cardanobile, Stefano; Rotter, Stefan

2011-01-01

Dynamic neuronal networks are a key paradigm of increasing importance in brain research, concerned with the functional analysis of biological neuronal networks and, at the same time, with the synthesis of artificial brain-like systems. In this context, neuronal network models serve as mathematical tools to understand the function of brains, but they might as well develop into future tools for enhancing certain functions of our nervous system. Here, we present and discuss our recent achievements in developing multiplicative point processes into a viable mathematical framework for spiking network modeling. The perspective is that the dynamic behavior of these neuronal networks is faithfully reflected by a set of non-linear rate equations, describing all interactions on the population level. These equations are similar in structure to Lotka-Volterra equations, well known by their use in modeling predator-prey relations in population biology, but abundant applications to economic theory have also been described. We present a number of biologically relevant examples for spiking network function, which can be studied with the help of the aforementioned correspondence between spike trains and specific systems of non-linear coupled ordinary differential equations. We claim that, enabled by the use of multiplicative point processes, we can make essential contributions to a more thorough understanding of the dynamical properties of interacting neuronal populations.

Numerical modelling to assess maintenance strategy management options for a small tidal inlet

NASA Astrophysics Data System (ADS)

Shaeri, Saeed; Tomlinson, Rodger; Etemad-Shahidi, Amir; Strauss, Darrell

2017-03-01

Small tidal inlets are found to be more sensitive to anthropogenic alteration than their larger counterparts. Such alterations, although typically supported by technical design reports, sometimes require amendments or modification. One of the most suitable tools to conduct the necessary studies in this regard is numerical modelling, since the behaviour of the inlet system in response to proposed remedial actions, can easily be identified. In this paper, various alternative proposals are investigated to determine the most practical and viable option to mitigate the need for ongoing maintenance at a typical small, jettied tidal inlet. The main tool to investigate the alternatives is the hydro-sedimentological modelling of the inlet system, which was performed using the Delft3D software package. The proposed alternative entrance modifications were based upon structural alterations of the inlet system (such as a jetty extension or submerged weir) and non-structural scenarios (such as a change of the time of the dredging campaign or the deposition location of the dredged material). It was concluded that whilst a detailed study is inevitable in order to achieve a comprehensive design plan, based upon the results of this study the construction of a submerged weir at the entrance channel can satisfy the needs of most of the stakeholders, with justifiable costs over a longer period.

Emergent Properties of Interacting Populations of Spiking Neurons

PubMed Central

Cardanobile, Stefano; Rotter, Stefan

2011-01-01

Dynamic neuronal networks are a key paradigm of increasing importance in brain research, concerned with the functional analysis of biological neuronal networks and, at the same time, with the synthesis of artificial brain-like systems. In this context, neuronal network models serve as mathematical tools to understand the function of brains, but they might as well develop into future tools for enhancing certain functions of our nervous system. Here, we present and discuss our recent achievements in developing multiplicative point processes into a viable mathematical framework for spiking network modeling. The perspective is that the dynamic behavior of these neuronal networks is faithfully reflected by a set of non-linear rate equations, describing all interactions on the population level. These equations are similar in structure to Lotka-Volterra equations, well known by their use in modeling predator-prey relations in population biology, but abundant applications to economic theory have also been described. We present a number of biologically relevant examples for spiking network function, which can be studied with the help of the aforementioned correspondence between spike trains and specific systems of non-linear coupled ordinary differential equations. We claim that, enabled by the use of multiplicative point processes, we can make essential contributions to a more thorough understanding of the dynamical properties of interacting neuronal populations. PMID:22207844

Projecting the long-term biogeochemical impacts of a diverse agroforestry system in the Midwest

NASA Astrophysics Data System (ADS)

Wolz, K. J.; DeLucia, E. H.; Paul, R. F.

2014-12-01

Annual, monoculture cropping systems have become the standard agricultural model in the Midwestern US. Unintended consequences of these systems include surface and groundwater pollution, greenhouse gas emissions, loss of biodiversity, and soil erosion. Diverse agroforestry (DA) systems dominated by fruit and nut trees/shrubs have been proposed as an agricultural model for the Midwestern US that can restore ecosystem services while simultaneously providing economically viable and industrially relevant staple food crops. A DA system including six species of fruit and nut crops was established on long-time conventional agricultural land at the University of Illinois at Urbana-Champaign in 2012, with the conventional corn-soybean rotation (CSR) as a control. Initial field measurements of the nitrogen and water cycles during the first two years of transition have indicated a significant decrease in N losses and modification of the seasonal evapotranspiration (ET) pattern. While these early results suggest that the land use transition from CSR to DA can have positive biogeochemical consequences, models must be utilized to make long-term biogeochemical projections in agroforestry systems. Initial field measurements of plant phenology, net N2O flux, nitrate leaching, soil respiration, and soil moisture were used to parameterize the DA system within the DayCENT biogeochemical model as the "savanna" ecosystem type. The model was validated with an independent subset of field measurements and then run to project biogeochemical cycling in the DA system for 25 years past establishment. Model results show that N losses via N2O emission or nitrate leaching reach a minimum within the first 5 years and then maintain this tight cycle into the future. While early ET field measurements revealed similar magnitudes between the DA and CSR systems, modeled ET continued to increase for the DA system throughout the projected time since the trees would continue to grow larger. These modeling results illustrate the potential long-term biogeochemical impacts that can be generated by a land-use transition to a diverse agroforestry system in the Midwest.

Chemical hydrogen storage material property guidelines for automotive applications

NASA Astrophysics Data System (ADS)

Semelsberger, Troy A.; Brooks, Kriston P.

2015-04-01

Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (<20 atm), moderate temperature operation (<200 °C), system gravimetric capacities (>0.05 kg H2/kgsystem), and system volumetric capacities (>0.05 kg H2/Lsystem). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storage material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid-phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material properties-and most important, their implications on system mass, system volume and system performance.

Automated Synthesis of Architecture of Avionic Systems

NASA Technical Reports Server (NTRS)

Chau, Savio; Xu, Joseph; Dang, Van; Lu, James F.

2006-01-01

The Architecture Synthesis Tool (AST) is software that automatically synthesizes software and hardware architectures of avionic systems. The AST is expected to be most helpful during initial formulation of an avionic-system design, when system requirements change frequently and manual modification of architecture is time-consuming and susceptible to error. The AST comprises two parts: (1) an architecture generator, which utilizes a genetic algorithm to create a multitude of architectures; and (2) a functionality evaluator, which analyzes the architectures for viability, rejecting most of the non-viable ones. The functionality evaluator generates and uses a viability tree a hierarchy representing functions and components that perform the functions such that the system as a whole performs system-level functions representing the requirements for the system as specified by a user. Architectures that survive the functionality evaluator are further evaluated by the selection process of the genetic algorithm. Architectures found to be most promising to satisfy the user s requirements and to perform optimally are selected as parents to the next generation of architectures. The foregoing process is iterated as many times as the user desires. The final output is one or a few viable architectures that satisfy the user s requirements.

A polychromatic adaption of the Beer-Lambert model for spectral decomposition

NASA Astrophysics Data System (ADS)

Sellerer, Thorsten; Ehn, Sebastian; Mechlem, Korbinian; Pfeiffer, Franz; Herzen, Julia; Noël, Peter B.

2017-03-01

We present a semi-empirical forward-model for spectral photon-counting CT which is fully compatible with state-of-the-art maximum-likelihood estimators (MLE) for basis material line integrals. The model relies on a minimum calibration effort to make the method applicable in routine clinical set-ups with the need for periodic re-calibration. In this work we present an experimental verifcation of our proposed method. The proposed method uses an adapted Beer-Lambert model, describing the energy dependent attenuation of a polychromatic x-ray spectrum using additional exponential terms. In an experimental dual-energy photon-counting CT setup based on a CdTe detector, the model demonstrates an accurate prediction of the registered counts for an attenuated polychromatic spectrum. Thereby deviations between model and measurement data lie within the Poisson statistical limit of the performed acquisitions, providing an effectively unbiased forward-model. The experimental data also shows that the model is capable of handling possible spectral distortions introduced by the photon-counting detector and CdTe sensor. The simplicity and high accuracy of the proposed model provides a viable forward-model for MLE-based spectral decomposition methods without the need of costly and time-consuming characterization of the system response.

Hands-On Hydroponics

ERIC Educational Resources Information Center

Carver, Jeffrey; Wasserman, Bradley

2012-01-01

Hydroponics is a process in which plants are grown using nutrient-rich water instead of soil. Because this process maximizes the use of water and nutrients--providing only what the plant uses in controlled and easily maintained systems--it is a viable alternative to traditional farming methods. The amount of control in these systems also ensures…

76 FR 24848 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-03

...: USDA Web Based Supply Chain Management System (WBSCMs). OMB Control Number: 0581--NEW. Summary of... using the secure Web Based Supply Chain Management System (WBSCM). Vendors must be registered, and have... assists AMS with making a determination whether a business is viable and capable of supplying product to...

Automated analysis of biological oscillator models using mode decomposition.

PubMed

Konopka, Tomasz

2011-04-01

Oscillating signals produced by biological systems have shapes, described by their Fourier spectra, that can potentially reveal the mechanisms that generate them. Extracting this information from measured signals is interesting for the validation of theoretical models, discovery and classification of interaction types, and for optimal experiment design. An automated workflow is described for the analysis of oscillating signals. A software package is developed to match signal shapes to hundreds of a priori viable model structures defined by a class of first-order differential equations. The package computes parameter values for each model by exploiting the mode decomposition of oscillating signals and formulating the matching problem in terms of systems of simultaneous polynomial equations. On the basis of the computed parameter values, the software returns a list of models consistent with the data. In validation tests with synthetic datasets, it not only shortlists those model structures used to generate the data but also shows that excellent fits can sometimes be achieved with alternative equations. The listing of all consistent equations is indicative of how further invalidation might be achieved with additional information. When applied to data from a microarray experiment on mice, the procedure finds several candidate model structures to describe interactions related to the circadian rhythm. This shows that experimental data on oscillators is indeed rich in information about gene regulation mechanisms. The software package is available at http://babylone.ulb.ac.be/autoosc/.

Proflavine-mediated inactivation of Salmonella dublin exposed to visible sunlight in natural fresh water.

PubMed

Kussovski, V K; Hristov, A E; Radoucheva, T S

2001-01-01

The survival of Salmonella dublin exposed to visible sunlight, and heterotrophic bacteria in freshwater microcosms in the presence and absence of the photosensitizer proflavine, was studied. Enumeration of S. dublin and the heterotrophic bacteria showed that in both illuminated and nonilluminated systems (without proflavine) the bacteria remained viable and culturable for at least 6 days. The optimal proflavine concentration (no effect in the dark and a maximal photoinactivation of salmonellae after irradiation) was 2 mg l(-1). In contrast to S. dublin, the heterotrophic bacteria overcame the initial inhibitory effect of proflavine. The possible use of photosterilization against contamination with pathogenic bacteria in water model ecosystems, is discussed.

Space power distribution system technology. Volume 1: Reference EPS design

NASA Technical Reports Server (NTRS)

Decker, D. K.; Cannady, M. D.; Cassinelli, J. E.; Farber, B. F.; Lurie, C.; Fleck, G. W.; Lepisto, J. W.; Massner, A.; Ritterman, P. F.

1983-01-01

The multihundred kilowatt electrical power aspects of a mannable space platform in low Earth orbit is analyzed from a cost and technology viewpoint. At the projected orbital altitudes, Shuttle launch and servicing are technically and economically viable. Power generation is specified as photovoltaic consistent with projected planning. The cost models and trades are based upon a zero interest rate (the government taxes concurrently as required), constant dollars (1980), and costs derived in the first half of 1980. Space platform utilization of up to 30 years is evaluated to fully understand the impact of resupply and replacement as satellite missions are extended. Such lifetimes are potentially realizable with Shuttle servicing capability and are economically desirable.

Meeting the DHCP Challenge: A Model for Implementing a Decentralized Hospital Computer Program

PubMed Central

Catellier, Julie; Benway, Paula K.; Perez, Kathleen

1987-01-01

The James A. Haley Veterans' Hospital in Tampa has been a consistent leader in the implementation of automated systems within the VA. Our approach has been essentially to focus on obtaining maximum user involvement and contribution to the automation program within the Medical Center. Since clinical acceptance is vital to a viable program, a great deal of our efforts have been aimed at maximizing the training and participation of physicians, nurses and other clinical staff. The following is a description of our organization structure relative to this topic. We believe it to be a highly workable approach which can be easily implemented structurally at any hospital — public or private.

Modelling dynamic transport and adsorption of arsenic in soil-bed filters for long-term performance evaluation

NASA Astrophysics Data System (ADS)

Mondal, Sourav; Mondal, Raka; de, Sirshendu; Griffiths, Ian

2017-11-01

Purification of contaminated water following the safe water guidelines while generating sufficiently large throughput is a crucial requirement for the steady supply of safe water to large populations. Adsorption-based filtration processes using a multilayer soil bed has been posed as a viable method to achieve this goal. This work describes the theory of operation and prediction of the long-term behaviour of such a system. The fixed-bed column has a single input of contaminated water from the top and an output from the bottom. As the contaminant passes through the column, it is adsorbed by the medium. Like any other adsorption medium, the filter has a certain lifespan, beyond which the filtrate does not meet the safe limit of drinking water, which is defined as `breakthrough'. A mathematical model is developed that couples the fluid flow through the porous medium to the convective, diffusive and adsorptive transport of the contaminant. The results are validated with experimental observations and the model is then used to predict the breakthrough and lifetime of the filter. The key advantage of this model is that it can predict the long-term behaviour of any adsorption column system for any set of physical characteristics of the system. This worked was supported by the EPSRC Global Challenge Research Fund Institutional Sponsorship 2016.

Superstructure-based Design and Optimization of Batch Biodiesel Production Using Heterogeneous Catalysts

NASA Astrophysics Data System (ADS)

Nuh, M. Z.; Nasir, N. F.

2017-08-01

Biodiesel as a fuel comprised of mono alkyl esters of long chain fatty acids derived from renewable lipid feedstock, such as vegetable oil and animal fat. Biodiesel production is complex process which need systematic design and optimization. However, no case study using the process system engineering (PSE) elements which are superstructure optimization of batch process, it involves complex problems and uses mixed-integer nonlinear programming (MINLP). The PSE offers a solution to complex engineering system by enabling the use of viable tools and techniques to better manage and comprehend the complexity of the system. This study is aimed to apply the PSE tools for the simulation of biodiesel process and optimization and to develop mathematical models for component of the plant for case A, B, C by using published kinetic data. Secondly, to determine economic analysis for biodiesel production, focusing on heterogeneous catalyst. Finally, the objective of this study is to develop the superstructure for biodiesel production by using heterogeneous catalyst. The mathematical models are developed by the superstructure and solving the resulting mixed integer non-linear model and estimation economic analysis by using MATLAB software. The results of the optimization process with the objective function of minimizing the annual production cost by batch process from case C is 23.2587 million USD. Overall, the implementation a study of process system engineering (PSE) has optimized the process of modelling, design and cost estimation. By optimizing the process, it results in solving the complex production and processing of biodiesel by batch.

Reinforcement sensitivity theory and alcohol outcome expectancies in early adolescence.

PubMed

Lopez-Vergara, Hector I; Colder, Craig R; Hawk, Larry W; Wieczorek, William F; Eiden, Rina D; Lengua, Liliana J; Read, Jennifer P

2012-03-01

Little research has examined the development of alcohol expectancies in childhood, a notable omission as expectancies are viable targets for prevention programs. Moreover, limited alcohol expectancies research has been conducted from the perspective of psychobiological models of motivation despite the strong conceptual links between such models and cognitive models of alcohol use. To examine if the associations between individual differences from the revised reinforcement sensitivity theory (Gray JA, McNaughton N. The Neuropsychology of Anxiety: An Enquiry into the Functions of the Septo-hippocampal System (2nd ed.). Oxford, UK: Oxford University Press, 2000) and alcohol use is mediated by alcohol expectancies in a large community sample of early adolescents using a prospective design. 378 families (1 caregiver; 1 child) were recruited via random digit phone call using a prospective design. Our findings suggest that both a strong behavioral approach system and fight-flight or freeze system were associated with high levels of positive outcome expectancies, which subsequently predicted an increase in likelihood of alcohol use. There was also some evidence that drive (an aspect of behavioral approach system) was also positively associated with negative expectancies, which subsequently predicted a low probability of alcohol use. Individual differences in reinforcement sensitivity may influence the acquisition of positive and negative outcome expectancies, thereby potentially influencing the likelihood of alcohol use in early adolescence. Thus, reinforcement sensitivity theory is a promising theory to account for the link between neural models of addiction and early acquisition of alcohol use in humans.

Revisiting the two-layer hypothesis: coexistence of alternative functional rooting strategies in savannas.

PubMed

Holdo, Ricardo M

2013-01-01

The two-layer hypothesis of tree-grass coexistence posits that trees and grasses differ in rooting depth, with grasses exploiting soil moisture in shallow layers while trees have exclusive access to deep water. The lack of clear differences in maximum rooting depth between these two functional groups, however, has caused this model to fall out of favor. The alternative model, the demographic bottleneck hypothesis, suggests that trees and grasses occupy overlapping rooting niches, and that stochastic events such as fires and droughts result in episodic tree mortality at various life stages, thus preventing trees from otherwise displacing grasses, at least in mesic savannas. Two potential problems with this view are: 1) we lack data on functional rooting profiles in trees and grasses, and these profiles are not necessarily reflected by differences in maximum or physical rooting depth, and 2) subtle, difficult-to-detect differences in rooting profiles between the two functional groups may be sufficient to result in coexistence in many situations. To tackle this question, I coupled a plant uptake model with a soil moisture dynamics model to explore the environmental conditions under which functional rooting profiles with equal rooting depth but different depth distributions (i.e., shapes) can coexist when competing for water. I show that, as long as rainfall inputs are stochastic, coexistence based on rooting differences is viable under a wide range of conditions, even when these differences are subtle. The results also indicate that coexistence mechanisms based on rooting niche differentiation are more viable under some climatic and edaphic conditions than others. This suggests that the two-layer model is both viable and stochastic in nature, and that a full understanding of tree-grass coexistence and dynamics may require incorporating fine-scale rooting differences between these functional groups and realistic stochastic climate drivers into future models.

Revisiting the Two-Layer Hypothesis: Coexistence of Alternative Functional Rooting Strategies in Savannas

PubMed Central

Holdo, Ricardo M.

2013-01-01

The two-layer hypothesis of tree-grass coexistence posits that trees and grasses differ in rooting depth, with grasses exploiting soil moisture in shallow layers while trees have exclusive access to deep water. The lack of clear differences in maximum rooting depth between these two functional groups, however, has caused this model to fall out of favor. The alternative model, the demographic bottleneck hypothesis, suggests that trees and grasses occupy overlapping rooting niches, and that stochastic events such as fires and droughts result in episodic tree mortality at various life stages, thus preventing trees from otherwise displacing grasses, at least in mesic savannas. Two potential problems with this view are: 1) we lack data on functional rooting profiles in trees and grasses, and these profiles are not necessarily reflected by differences in maximum or physical rooting depth, and 2) subtle, difficult-to-detect differences in rooting profiles between the two functional groups may be sufficient to result in coexistence in many situations. To tackle this question, I coupled a plant uptake model with a soil moisture dynamics model to explore the environmental conditions under which functional rooting profiles with equal rooting depth but different depth distributions (i.e., shapes) can coexist when competing for water. I show that, as long as rainfall inputs are stochastic, coexistence based on rooting differences is viable under a wide range of conditions, even when these differences are subtle. The results also indicate that coexistence mechanisms based on rooting niche differentiation are more viable under some climatic and edaphic conditions than others. This suggests that the two-layer model is both viable and stochastic in nature, and that a full understanding of tree-grass coexistence and dynamics may require incorporating fine-scale rooting differences between these functional groups and realistic stochastic climate drivers into future models. PMID:23950900

In vitro study on the effect of doxycycline on the microbial activity of soil determined by redox-potential measuring system.

PubMed

Szakmár, Katalin; Reichart, Olivér; Szatmári, István; Erdősi, Orsolya; Szili, Zsuzsanna; László, Noémi; Székely Körmöczy, Péter; Laczay, Péter

2014-09-01

The potential effect of doxycycline on the microbial activity was investigated in three types of soil. Soil samples were spiked with doxycycline, incubated at 25°C and tested at 0, 2, 4 and 6 days after treatment. The microbiological activity of the soil was characterized by the viable count determined by plate pouring and by the time necessary to reach a defined rate of the redox-potential decrease termed as time to detection (TTD).The viable count of the samples was not changed during the storage. The TTD values, however exhibited a significant increase in the 0.2-1.6 mg/kg doxycycline concentration range compared to the untreated samples indicating concentration-dependent inhibitory effect on microbial activity. The potency of the effect was different in the 3 soil types. To describe the combined effect of the doxycycline concentration and time on the biological activity of one type of soil a mathematical model was constructed and applied.The change of microbial metabolic rate could be measured also without (detectable) change of microbial count when the traditional microbiological methods are not applicable. The applied new redox potential measurement-based method is a simple and useful procedure for the examination of microbial activity of soil and its potential inhibition by antibiotics.

Implementing systems thinking for infection prevention: The cessation of repeated scabies outbreaks in a respiratory care ward.

PubMed

Chuang, Sheuwen; Howley, Peter P; Lin, Shih-Hua

2015-05-01

Root cause analysis (RCA) is often adopted to complement epidemiologic investigation for outbreaks and infection-related adverse events in hospitals; however, RCA has been argued to have limited effectiveness in preventing such events. We describe how an innovative systems analysis approach halted repeated scabies outbreaks, and highlight the importance of systems thinking for outbreaks analysis and sustaining effective infection prevention and control. Following RCA for a third successive outbreak of scabies over a 17-month period in a 60-bed respiratory care ward of a Taiwan hospital, a systems-oriented event analysis (SOEA) model was used to reanalyze the outbreak. Both approaches and the recommendations were compared. No nosocomial scabies have been reported for more than 1975 days since implementation of the SOEA. Previous intervals between seeming eradication and repeat outbreaks following RCA were 270 days and 180 days. Achieving a sustainable positive resolution relied on applying systems thinking and the holistic analysis of the system, not merely looking for root causes of events. To improve the effectiveness of outbreaks analysis and infection control, an emphasis on systems thinking is critical, along with a practical approach to ensure its effective implementation. The SOEA model provides the necessary framework and is a viable complementary approach, or alternative, to RCA. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Tests of the E-Z Reader Model: Exploring the Interface between Cognition and Eye-Movement Control

ERIC Educational Resources Information Center

Pollatsek, Alexander; Reichle, Erik D.; Rayner, Keith

2006-01-01

This paper is simultaneously a test and refinement of the E-Z Reader model and an exploration of the interrelationship between visual and language processing and eye-movements in reading. Our modeling indicates that the assumption that words in text are processed serially by skilled readers is a viable and attractive hypothesis, as it accounts not…

Comparisons of a Constrained Least Squares Model versus Human-in-the-Loop for Spectral Unmixing to Determine Material Type of GEO Debris

NASA Technical Reports Server (NTRS)

Abercromby, Kira J.; Rapp, Jason; Bedard, Donald; Seitzer, Patrick; Cardona, Tommaso; Cowardin, Heather; Barker, Ed; Lederer, Susan

2013-01-01

Constrained Linear Least Squares model is generally more accurate than the "human-in-the-loop". However, "human-in-the-loop" can remove materials that make no sense. The speed of the model in determining a "first cut" at the material ID makes it a viable option for spectral unmixing of debris objects.

Rapid enumeration of viable bacteria by image analysis

NASA Technical Reports Server (NTRS)

Singh, A.; Pyle, B. H.; McFeters, G. A.

1989-01-01

A direct viable counting method for enumerating viable bacteria was modified and made compatible with image analysis. A comparison was made between viable cell counts determined by the spread plate method and direct viable counts obtained using epifluorescence microscopy either manually or by automatic image analysis. Cultures of Escherichia coli, Salmonella typhimurium, Vibrio cholerae, Yersinia enterocolitica and Pseudomonas aeruginosa were incubated at 35 degrees C in a dilute nutrient medium containing nalidixic acid. Filtered samples were stained for epifluorescence microscopy and analysed manually as well as by image analysis. Cells enlarged after incubation were considered viable. The viable cell counts determined using image analysis were higher than those obtained by either the direct manual count of viable cells or spread plate methods. The volume of sample filtered or the number of cells in the original sample did not influence the efficiency of the method. However, the optimal concentration of nalidixic acid (2.5-20 micrograms ml-1) and length of incubation (4-8 h) varied with the culture tested. The results of this study showed that under optimal conditions, the modification of the direct viable count method in combination with image analysis microscopy provided an efficient and quantitative technique for counting viable bacteria in a short time.

Results from flamelet and non-flamelet models for supersonic combustion

NASA Astrophysics Data System (ADS)

Ladeinde, Foluso; Li, Wenhai

2017-11-01

Air-breathing propulsion systems (scramjets) have been identified as a viable alternative to rocket engines for improved efficiency. A scramjet engine, which operates at flight Mach numbers around 7 or above, is characterized by the existence of supersonic flow conditions in the combustor. In a dual-mode scramjet, this phenomenon is possible because of the relatively low value of the equivalence ratio and high stagnation temperature, which, together, inhibits thermal choking downstream of transverse injectors. The flamelet method has been our choice for turbulence-combustion interaction modeling and we have extended the basic approach in several dimensions, with a focus on the way the pressure and progress variable are modeled. Improved results have been obtained. We have also examined non-flamelet models, including laminar chemistry (QL), eddy dissipation concept (EDC), and partially-stirred reactor (PaSR). The pressure/progress variable-corrected simulations give better results compared with the original model, with reaction rates that are lower than those from EDC and PaSR. In general, QL tends to over-predict the reaction rate for the supersonic combustion problems investigated in our work.

Conservation Reserve Program effects on floodplain land cover management.

PubMed

Jobe, Addison; Kalra, Ajay; Ibendahl, Elise

2018-05-15

Growing populations and industrialized agriculture practices have eradicated much of the United States wetlands along river floodplains. One program available for the restoration of floodplains is the Conservation Reserve Program (CRP). The current research explores the effects CRP land change has on flooding zones, utilizing Flood Modeller and HEC-RAS. Flood Modeller is proven a viable tool for flood modeling within the United States when compared to HEC-RAS. Application of the software is used in the Nodaway River system located in the western halves of Iowa and Missouri to model effects of introducing new forest areas within the region. Flood stage during the conversion first decreases in the early years, before rising to produce greater heights. Flow velocities where CRP land is present are reduced for long-term scopes. Velocity reduction occurs as the Manning's roughness increases due to tree diameter and brush density. Flood zones become more widespread with the implementation of CRP. Future model implementations are recommended to witness the effects of smaller flood recurrence intervals. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Conceptual Aerospace Vehicle Structural System Modeling, Analysis and Design Process

NASA Technical Reports Server (NTRS)

Mukhopadhyay, Vivek

2007-01-01

A process for aerospace structural concept analysis and design is presented, with examples of a blended-wing-body fuselage, a multi-bubble fuselage concept, a notional crew exploration vehicle, and a high altitude long endurance aircraft. Aerospace vehicle structures must withstand all anticipated mission loads, yet must be designed to have optimal structural weight with the required safety margins. For a viable systems study of advanced concepts, these conflicting requirements must be imposed and analyzed early in the conceptual design cycle, preferably with a high degree of fidelity. In this design process, integrated multidisciplinary analysis tools are used in a collaborative engineering environment. First, parametric solid and surface models including the internal structural layout are developed for detailed finite element analyses. Multiple design scenarios are generated for analyzing several structural configurations and material alternatives. The structural stress, deflection, strain, and margins of safety distributions are visualized and the design is improved. Over several design cycles, the refined vehicle parts and assembly models are generated. The accumulated design data is used for the structural mass comparison and concept ranking. The present application focus on the blended-wing-body vehicle structure and advanced composite material are also discussed.

Possible Effects of Synaptic Imbalances on Oligodendrocyte–Axonic Interactions in Schizophrenia: A Hypothetical Model

PubMed Central

Mitterauer, Bernhard J.; Kofler-Westergren, Birgitta

2011-01-01

A model of glial–neuronal interactions is proposed that could be explanatory for the demyelination identified in brains with schizophrenia. It is based on two hypotheses: (1) that glia–neuron systems are functionally viable and important for normal brain function, and (2) that disruption of this postulated function disturbs the glial categorization function, as shown by formal analysis. According to this model, in schizophrenia receptors on astrocytes in glial–neuronal synaptic units are not functional, loosing their modulatory influence on synaptic neurotransmission. Hence, an unconstrained neurotransmission flux occurs that hyperactivates the axon and floods the cognate receptors of neurotransmitters on oligodendrocytes. The excess of neurotransmitters may have a toxic effect on oligodendrocytes and myelin, causing demyelination. In parallel, an increasing impairment of axons may disconnect neuronal networks. It is formally shown how oligodendrocytes normally categorize axonic information processing via their processes. Demyelination decomposes the oligodendrocyte–axonic system making it incapable to generate categories of information. This incoherence may be responsible for symptoms of disorganization in schizophrenia, such as thought disorder, inappropriate affect and incommunicable motor behavior. In parallel, the loss of oligodendrocytes affects gap junctions in the panglial syncytium, presumably responsible for memory impairment in schizophrenia. PMID:21647404

Chemical hydrogen storage material property guidelines for automotive applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semelsberger, Troy; Brooks, Kriston P.

2015-04-01

Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (<20 atm), moderate temperature operation (<200 C), system gravimetric capacities (>0.05 kg H2/kg system), and system volumetric capacities (>0.05 kg H2/L system). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storagemore » material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material propertiesdand most important, their implications on system mass, system volume and system performance.« less

Proposed Framework for Determining Added Mass of Orion Drogue Parachutes

NASA Technical Reports Server (NTRS)

Fraire, Usbaldo, Jr.; Dearman, James; Morris, Aaron

2011-01-01

The Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS) project is executing a program to qualify a parachute system for a next generation human spacecraft. Part of the qualification process involves predicting parachute riser tension during system descent with flight simulations. Human rating the CPAS hardware requires a high degree of confidence in the simulation models used to predict parachute loads. However, uncertainty exists in the heritage added mass models used for loads predictions due to a lack of supporting documentation and data. Even though CPAS anchors flight simulation loads predictions to flight tests, extrapolation of these models outside the test regime carries the risk of producing non-bounding loads. A set of equations based on empirically derived functions of skirt radius is recommended as the simplest and most viable method to test and derive an enhanced added mass model for an inflating parachute. This will increase confidence in the capability to predict parachute loads. The selected equations are based on those published in A Simplified Dynamic Model of Parachute Inflation by Dean Wolf. An Ames 80x120 wind tunnel test campaign is recommended to acquire the reefing line tension and canopy photogrammetric data needed to quantify the terms in the Wolf equations and reduce uncertainties in parachute loads predictions. Once the campaign is completed, the Wolf equations can be used to predict loads in a typical CPAS Drogue Flight test. Comprehensive descriptions of added mass test techniques from the Apollo Era to the current CPAS project are included for reference.

Space-based solar power conversion and delivery systems study. Volume 5: Economic analysis

NASA Technical Reports Server (NTRS)

1977-01-01

Space-based solar power conversion and delivery systems are studied along with a variety of economic and programmatic issues relevant to their development and deployment. The costs, uncertainties and risks associated with the current photovoltaic Satellite Solar Power System (SSPS) configuration, and issues affecting the development of an economically viable SSPS development program are addressed. In particular, the desirability of low earth orbit (LEO) and geosynchronous (GEO) test satellites is examined and critical technology areas are identified. The development of SSPS unit production (nth item), and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM) are reported. The RAM was then used to evaluate the current SSPS configuration expected costs and cost-risk associated with this configuration. By examining differential costs and cost-risk as a function of postulated technology developments, the critical technologies, that is, those which drive costs and/or cost-risk, are identified. It is shown that the key technology area deals with productivity in space, that is, the ability to fabricate and assemble large structures in space, not, as might be expected, with some hardware component technology.

Application of a Geographic Information System for regridding a ground-water flow model of the Columbia Plateau Regional Aquifer System, Walla Walla River basin, Oregon-Washington

USGS Publications Warehouse

Darling, M.E.; Hubbard, L.E.

1994-01-01

Computerized Geographic Information Systems (GIS) have become viable and valuable tools for managing,analyzing, creating, and displaying data for three-dimensional finite-difference ground-water flow models. Three GIS applications demonstrated in this study are: (1) regridding of data arrays from an existing large-area, low resolution ground-water model to a smaller, high resolution grid; (2) use of GIS techniques for assembly of data-input arrays for a ground-water model; and (3) use of GIS for rapid display of data for verification, for checking of ground-water model output, and for the cre.ation of customized maps for use in reports. The Walla Walla River Basin was selected as the location for the demonstration because (1) data from a low resolution ground-water model (Columbia Plateau Regional Aquifer System Analysis [RASA]) were available and (2) concern for long-term use of water resources for irrigation in the basin. The principal advantage of regridding is that it may provide the ability to more precisely calibrate a model, assuming chat a more detailed coverage of data is available, and to evaluate the numerical errors associated with a particular grid design.Regridding gave about an 8-fold increase in grid-node density.Several FORTRAN programs were developed to load the regridded ground-water data into a finite-difference modular model as model-compatible input files for use in a steady-state model run.To facilitate the checking and validating of the GIS regridding process, maps and tabular reports were produced for each of eight ground-water parameters by model layer. Also, an automated subroutine that was developed to view the model-calculated water levels in cross-section will aid in the synthesis and interpretation of model results.

Grazing of particle-associated bacteria-an elimination of the non-viable fraction.

PubMed

Gonsalves, Maria-Judith; Fernandes, Sheryl Oliveira; Priya, Madasamy Lakshmi; LokaBharathi, Ponnapakkam Adikesavan

Quantification of bacteria being grazed by microzooplankton is gaining importance since they serve as energy subsidies for higher trophic levels which consequently influence fish production. Hence, grazing pressure on viable and non-viable fraction of free and particle-associated bacteria in a tropical estuary controlled mainly by protist grazers was estimated using the seawater dilution technique. In vitro incubations over a period of 42h showed that at the end of 24h, growth coefficient (k) of particle-associated bacteria was 9 times higher at 0.546 than that of free forms. Further, 'k' value of viable cells on particles was double that of free forms at 0.016 and 0.007, respectively. While bacteria associated with particles were grazed (coefficient of removal (g)=0.564), the free forms were relatively less grazed indicating that particle-associated bacteria were exposed to grazers in these waters. Among the viable and non-viable forms, 'g' of non-viable fraction (particle-associated bacteria=0.615, Free=0.0086) was much greater than the viable fraction (particle-associated bacteria=0.056, Free=0.068). Thus, grazing on viable cells was relatively low in both the free and attached states. These observations suggest that non-viable forms of particle-associated bacteria were more prone to grazing and were weeded out leaving the viable cells to replenish the bacterial standing stock. Particle colonization could thus be a temporary refuge for the "persistent variants" where the viable fraction multiply and release their progeny. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Secular Resonances During Main-Sequence and Post-Main-Sequence Planetary System Dynamics

NASA Astrophysics Data System (ADS)

Smallwood, Jeremy L.

We investigate gravitational perturbations of an asteroid belt by secular resonances. We ap- ply analytic and numerical models to main-sequence and post-main-sequence planetary systems. First, we investigate how the asteroid impact rate on the Earth is affected by the architecture of the planetary system. We find that the nu6 resonance plays an important role in the asteroid collision rate with the Earth. Compared to exoplanetary systems, the solar system is somewhat special in its lack of a super-Earth mass planet in the inner solar system. We therefore consider the effects of the presence of a super-Earth in the terrestrial planet region. We find a significant effect for super-Earths with a mass of around 10 M_{Earth} and a separation greater than about 0.7 AU. These results have implications for the habitability of exoplanetary systems. Secondly, we model white dwarf pollution by asteroids from secular resonances. In the past few decades, observations have revealed signatures of metals polluting the atmospheres of white dwarfs that require a continu- ous accretion of asteroids. We show that secular resonances driven by two outer companions can provide a source of pollution if an inner terrestrial planet is engulfed during the red-giant branch phase. Secular resonances may be a viable mechanism for the pollution of white dwarfs in a variety of exoplanetary system architectures including systems with two giant planets and systems with one giant planet and a binary star companion.

Rat brain sagittal organotypic slice cultures as an ex vivo dopamine cell loss system.

PubMed

McCaughey-Chapman, Amy; Connor, Bronwen

2017-02-01

Organotypic brain slice cultures are a useful tool to study neurological function as they provide a more complex, 3-dimensional system than standard 2-dimensional in vitro cell cultures. Building on a previously developed mouse brain slice culture protocol, we have developed a rat sagittal brain slice culture system as an ex vivo model of dopamine cell loss. We show that rat brain organotypic slice cultures remain viable for up to 6 weeks in culture. Using Fluoro-Gold axonal tracing, we demonstrate that the slice 3-dimensional cytoarchitecture is maintained over a 4 week culturing period, with particular focus on the nigrostriatal pathway. Treatment of the cultures with 6-hydroxydopamine and desipramine induces a progressive loss of Fluoro-Gold-positive nigral cells with a sustained loss of tyrosine hydroxylase-positive nigral cells. This recapitulates the pattern of dopaminergic degeneration observed in the rat partial 6-hydroxydopamine lesion model and, most importantly, the progressive pathology of Parkinson's disease. Our slice culture platform provides an advance over other systems, as we demonstrate for the first time 3-dimensional cytoarchitecture maintenance of rat nigrostriatal sagittal slices for up to 6 weeks. Our ex vivo organotypic slice culture system provides a long term cellular platform to model Parkinson's disease, allowing for the elucidation of mechanisms involved in dopaminergic neuron degeneration and the capability to study cellular integration and plasticity ex vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

Promoting Preservice Teacher Reflectivity: Van Manen May Represent a Viable Model

ERIC Educational Resources Information Center

Ballard, Kristy K.; McBride, Ron

2010-01-01

From Dewey (1933) to present, reflectivity is an important component of teacher education. Little information exists that specifically addresses when changes in reflectivity might occur. Therefore, the purpose of this study was: (a) to apply Van Manen's model to outcomes to examine levels of, and changes in, reflectivity and (b) to verify the…

The Schoolwide Cluster Grouping Model: Restructuring Gifted Education Services for the 21st Century

ERIC Educational Resources Information Center

Brulles, Dina; Winebrenner, Susan

2011-01-01

Schools today are experiencing dramatic changes in how they serve gifted students. Gifted programs that have prevailed for years are disappearing. In response, an increasing number of schools are turning to the Schoolwide Cluster Grouping Model (SCGM) to serve their gifted students. When implemented well, the SCGM represents one viable solution…

Reduced infectivity of waterborne viable but nonculturable Helicobacter pylori strain SS1 in mice.

PubMed

Boehnke, Kevin F; Eaton, Kathryn A; Fontaine, Clinton; Brewster, Rebecca; Wu, Jianfeng; Eisenberg, Joseph N S; Valdivieso, Manuel; Baker, Laurence H; Xi, Chuanwu

2017-08-01

Helicobacter pylori infection has been consistently associated with lack of access to clean water and proper sanitation, but no studies have demonstrated that the transmission of viable but nonculturable (VBNC) H. pylori can occur from drinking contaminated water. In this study, we used a laboratory mouse model to test whether waterborne VBNCH. pylori could cause gastric infection. We performed five mouse experiments to assess the infectivity of VBNCH. pylori in various exposure scenarios. VBNC viability was examined using Live/Dead staining and Biolog phenotype metabolism arrays. High doses of VBNCH. pylori in water were chosen to test the "worst-case" scenario for different periods of time. One experiment also investigated the infectious capabilities of VBNC SS1 using gavage. Further, immunocompromised mice were exposed to examine infectivity among potentially vulnerable groups. After exposure, mice were euthanized and their stomachs were examined for H. pylori infection using culture and PCR methodology. VBNC cells were membrane intact and retained metabolic activity. Mice exposed to VBNCH. pylori via drinking water and gavage were not infected, despite the various exposure scenarios (immunocompromised, high doses) that might have permitted infection with VBNCH. pylori. The positive controls exposed to viable, culturable H. pylori did become infected. While other studies that have used viable, culturable SS1 via gavage or drinking water exposures to successfully infect mice, in our study, waterborne VBNC SS1 failed to colonize mice under all test conditions. Future studies could examine different H. pylori strains in similar exposure scenarios to compare the relative infectivity of the VBNC vs the viable, culturable state, which would help inform future risk assessments of H. pylori in water. © 2017 The Authors. Helicobacter Published by John Wiley & Sons Ltd.

User perspectives on the usability of a regional health information exchange

PubMed Central

Ho, Yun-Xian; Cala, Cather Marie; Blakemore, Dana; Chen, Qingxia; Frisse, Mark E; Johnson, Kevin B

2011-01-01

Objective We assessed the usability of a health information exchange (HIE) in a densely populated metropolitan region. This grant-funded HIE had been deployed rapidly to address the imminent needs of the patient population and the need to draw wider participation from regional entities. Design We conducted a cross-sectional survey of individuals given access to the HIE at participating organizations and examined some of the usability and usage factors related to the technology acceptance model. Measurements We probed user perceptions using the Questionnaire for User Interaction Satisfaction, an author-generated Trust scale, and user characteristic questions (eg, age, weekly system usage time). Results Overall, users viewed the system favorably (ratings for all usability items were greater than neutral (one-sample Wilcoxon test, p<0.0014, Bonferroni-corrected for 35 tests). System usage was regressed on usability, trust, and demographic and user characteristic factors. Three usability factors were positively predictive of system usage: overall reactions (p<0 0.01), learning (p<0.05), and system functionality (p<0.01). Although trust is an important component in collaborative relationships, we did not find that user trust of other participating healthcare entities was significantly predictive of usage. An analysis of respondents' comments revealed ways to improve the HIE. Conclusion We used a rapid deployment model to develop an HIE and found that perceptions of system usability were positive. We also found that system usage was predicted well by some aspects of usability. Results from this study suggest that a rapid development approach may serve as a viable model for developing usable HIEs serving communities with limited resources. PMID:21622933

Triclosan loaded ureteral stents decrease proteus mirabilis 296 infection in a rabbit urinary tract infection model.

PubMed

Cadieux, Peter A; Chew, Ben H; Knudsen, Bodo E; Dejong, Kathy; Rowe, Elaine; Reid, Gregor; Denstedt, John D

2006-06-01

Infection and encrustation remain major limitations of ureteral stent use and to our knowledge no device has completely overcome these obstacles to date. Triclosan is a biocide currently used in a plethora of consumer and medical products that has recently been loaded into a ureteral stent. Using a rabbit model of UTI we examined the effects of triclosan impregnated stent segments on the growth and survival of Proteus mirabilis, a uropathogen commonly associated with device related UTI and encrustation. A total of 48 male New Zealand White rabbits were instilled transurethrally with 1 x 10(6) P. mirabilis 296. A stent curl from a triclosan eluting, Percuflex Plus or Optima ureteral stent was placed intravesically. Urine was cultured on days 1, 3 and 7. On day 7 the stents were assessed for encrustation and viable organisms, while the bladders were scored for the degree of inflammation. Throughout the study urine isolated from the triclosan group contained significantly fewer viable organisms than controls with 7 of 13 animals completely clearing the infection by day 7. Similarly 9 of 13 triclosan eluting stents showed no viable organisms upon recovery and the remaining 4 showed significantly fewer organisms than controls. Urine and stents in all controls were positive for P. mirabilis at all time points. Although there was no significant difference in encrustation among the groups, bladders harvested from the triclosan group demonstrated significantly less inflammation. Triclosan eluting stents greatly decreased P. mirabilis growth and survival in a rabbit UTI model compared to controls. These stents may prove useful for decreasing device related P. mirabilis UTIs.

Visualizing Opportunities: GIS Skills for Retail Marketing

ERIC Educational Resources Information Center

Wu, Peter Y.; Rathswohl, Eugene

2011-01-01

Business students need to develop skills in the intelligent use of information, especially spatial information, for decision-making. Geographic Information System (GIS) is a viable tool for that purpose. Yet the few GIS courses in the Information Systems curriculum offered in various business schools tend to focus on different concepts and skills.…

Critical Analysis of the Problems of Education in Pakistan: Possible Solutions

ERIC Educational Resources Information Center

Ahmad, Iqbal; ur Rehman, Kahil; Ali, Asghar; Khan, Itbar; Khan, Fazal Akber

2014-01-01

Education lays the foundation for political, social and economic development of any country. A viable education system enables the nation to achieve its national goals. Pakistan as a developing country has faced critical problems of education since its inception and therefore, the system of education has failed to deliver according to the…

An Optimized Microplate Assay System for Quantitative Evaluation of Plant Cell Wall Degrading Enzyme Activity of Fungal Culture Extracts

USDA-ARS?s Scientific Manuscript database

Developing enzyme cocktails for cellulosic biomass hydrolysis complementary to current cellulase systems is a critical step needed for economically viable biofuels production. Recent genomic analysis indicates that some plant pathogenic fungi are likely a largely untapped resource in which to prospe...

Efficacy of an ICALL Tutoring System and Process-Oriented Corrective Feedback

ERIC Educational Resources Information Center

Choi, Inn-Chull

2016-01-01

A Web-based form-focused intelligent computer-assisted language learning (ICALL) tutoring system equipped with a process-oriented corrective feedback function was developed to investigate the extent to which such a program may serve as a viable method of teaching grammar to Korean secondary and elementary students. The present study was also…

Homeschooling in America a Viable Option

ERIC Educational Resources Information Center

Terry, Bobby K.

2011-01-01

Since prayer was banned from the public school systems in 1962 and all religious references have been censored, the American Public School System has become completely secular in nature. Children today face a great deal of peer pressure especially when bad behavior is constantly glamorized in both the media and the press. Because of the lack of…

Development and Validation of an Observation System for Analyzing Teaching Roles.

ERIC Educational Resources Information Center

Southwell, Reba K.; Webb, Jeaninne N.

The construction and validation of a theoretically based sign system for the analysis of teaching roles in childhood education is described. A theoretical and empirical approach to validation were developed. In the first, the general concept of teacher role was identified as a viable construct for investigating characteristic patterns of classroom…

Managing climate change risks in rangeland systems [Chapter 15

Treesearch

Linda A. Joyce; Nadine A. Marshall

2017-01-01

The management of rangelands has long involved adapting to climate variability to ensure that economic enterprises remain viable and ecosystems sustainable; climate change brings the potential for change that surpasses the experience of humans within rangeland systems. Adaptation will require an intentionality to address the effects of climate change. Knowledge of...

Flow Injection Analysis and Liquid Chromatography for Multifunctional Chemical Analysis (MCA) Systems

ERIC Educational Resources Information Center

Mayo, Ana V.; Loegel, Thomas N.; Bretz, Stacey Lowery; Danielson, Neil D.

2013-01-01

The large class sizes of first-year chemistry labs makes it challenging to provide students with hands-on access to instrumentation because the number of students typically far exceeds the number of research-grade instruments available to collect data. Multifunctional chemical analysis (MCA) systems provide a viable alternative for large-scale…

From waste to resource: a systems-based approach to sustainable community development through equitable enterprise and agriculturally-derived polymeric composites

NASA Astrophysics Data System (ADS)

Teipel, Elisa

Rural communities in developing countries are most vulnerable to the plight of requiring repeated infusions of charitable aid over time. Micro-business opportunities that effectively break the cycle of poverty in resource-rich countries in the developing world are limited. However, a strong model for global commerce can break the cycle of donor-based economic supplements and limited local economic growth. Sustainable economic development can materialize when a robust framework combines engineering with the generous investment of profits back into the community. This research presents a novel, systems-based approach to sustainable community development in which a waste-to-resource methodology catalyzes the disruption of rural poverty. The framework developed in this thesis was applied to the rural communities of Cagmanaba and Badian, Philippines. An initial assessment of these communities showed that community members are extremely poor, but they possess an abundant natural resource: coconuts. The various parts of the coconut offer excellent potential value in global commerce. Today the sale of coconut water is on the rise, and coconut oil is an established $3 billion market annually that is also growing rapidly. Since these current industries harvest only two parts of the coconut (meat and water), the 50 billion coconuts that grow annually leave behind approximately 100 billion pounds of coconut shell and husk as agricultural waste. Coconuts thus provide an opportunity to create and test a waste-to-resource model. Intensive materials analysis, research, development, and optimization proved that coconut shell, currently burned as a fuel or discarded as agricultural waste, can be manufactured into high-grade coconut shell powder (CSP), which can be a viable filler in polymeric composites. This framework was modeled and tested as a case study in a manufacturing facility known as a Community Transformation Plant (CTP) in Cagmanaba, Philippines. The CTP enables local creation of globally viable products from agricultural waste. This researcher seeks to encourage the propagation of CTPs throughout developing communities worldwide, each profiting from its own waste-to-resource value.

Assessment of the commercial viability of selected options for on-orbit servicing (OOS)

NASA Astrophysics Data System (ADS)

Graham, Andrew Robert; Kingston, Jennifer

2015-12-01

The aim of this paper is to determine the commercial viability of on-orbit servicing of communications satellites in geostationary orbit. Previous studies have shown the technical feasibility of servicing as well as the financial viability of some missions, in particular refuelling, therefore this paper analyses these repair missions and life extension missions. A simple parametric model for simulating communications satellite revenue streams is developed and the results are used to determine the maximum possible revenue for a servicing satellite operator. From this, the maximum cost of the servicing satellite as a proportion of the cost of the communications satellite is determined under three profit scenarios representing zero profit, acceptable profit to an operator in a mature industry and acceptable profit to an operator in an emerging industry. The results show that while servicing is financially viable (zero profit scenario), those missions which result in an increase in Comsat life which is a multiple of the mission duration are more likely to be commercially viable. Refuelling is therefore viable in all cases but life extension in most cases is only marginally viable. Repair missions to satellites which are partially operable are also unlikely to deliver sufficient value to justify carrying out servicing. Also the timing of a servicing mission in relation to the expected remaining life expectancy is a major factor in determining the mission's viability.

Probiotics in the Space Food System: Delivery, Microgravity Effects, and the Potential Benefit to Crew Health

NASA Technical Reports Server (NTRS)

Castro, S. L.; Ott, C. M.; Douglas, G. L.

2014-01-01

As mission distance and duration increase, the need grows for non-invasive disease prevention and immunomodulation, especially given the limited medical response capability expected for these missions and the immune dysregulation documented in crew. Additionally, changes in diet, lifestyle, antibiotic usage, and the environmental stresses during spaceflight may alter crewmembers' intestinal microbiome. The addition of probiotic bacteria to the space food system is expected to confer immunostimulatory benefits on crewmembers, with the potential to counteract the immune dysregulation that has been documented in spaceflight. Based on previous studies that demonstrated unique microbiological responses to the low shear environment of spaceflight, probiotic organisms hold the potential to induce enhanced beneficial responses through mechanisms, such as beneficial interactions with human immune cells and repression of colonization of pathogens on the mucosa. The work presented here will begin to address two research gaps related to providing probiotics in spaceflight: 1) delivery, and 2) the effect of the low shear microgravity environment on probiotic attributes. The probiotic Lactobacillus acidophilus was selected for investigation due to its wide commercial use and documented benefits that include inhibition of virulence related gene expression in pathogens and mucosal stimulation of immune cells. The delivery system for probiotics has not been determined for spaceflight, where the food system is shelf stable and the lack of refrigeration prevents the use of traditional dairy delivery methods. In order to demonstrate the potential of the space food system to deliver viable probiotic bacteria to crewmembers, the probiotic L. acidophilus was packaged in high barrier flight packaging in nonfat dry milk (NFDM) or retained in commercial capsule form. Viable cells were enumerated over 8 months of storage at 22, 4, and -80ºC. The survival of L. acidophilus rehydrated in NFDM, in a PBS control, and directly from the capsule was also evaluated following stress challenge with simulated gastric and intestinal juices to determine the method that would deliver the most viable cells to the intestine, where they would be expected to confer beneficial effects. L. acidophilus was found to be stable to gastric and intestinal juice challenge when delivered in rehydrated NFDM, even after two hours of exposure. In comparison, L. acidophilus was reduced by 1-5 logs when exposed to gastric and intestinal juice directly and when rehydrated in a PBS control. Shelf life data indicated that L. acidophilus would require refrigerated or frozen storage to remain viable at adequate levels over the multi-year storage periods required for spaceflight. This study suggests that the protective effect provided by the dairy matrix, and not merely rehydration prior to consumption, extends probiotic viability and stress tolerance during storage in spaceflight and in simulated digestion conditions more adequately than a capsule. In addition to effective delivery, it is essential to understand the microgravity effects on the stress tolerances and genetic expression of probiotic bacteria to enable optimization of growth, survival, strain selection, and conferred benefits in spaceflight. In our current study, ground-based characterization of the growth, stress response, and transcriptomic response of L. acidophilus will be accomplished using the low shear modeled microgravity (LSMMG) culture environment in the rotating wall vessel (RWV). We hypothesize that L. acidophilus will maintain or improve its growth and stress response following culture in the LSMMG environment, and that transcriptomic analysis will define the associated molecular mechanism(s), resulting in the ability to optimize strain selection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Shaughnessy, Eric; Ardani, Kristen; Cutler, Dylan

Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domesticmore » water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.« less

Solar Plus: A Holistic Approach to Distributed Solar PV

DOE Office of Scientific and Technical Information (OSTI.GOV)

OShaughnessy, Eric J.; Ardani, Kristen B.; Cutler, Dylan S.

Solar 'plus' refers to an emerging approach to distributed solar photovoltaic (PV) deployment that uses energy storage and controllable devices to optimize customer economics. The solar plus approach increases customer system value through technologies such as electric batteries, smart domestic water heaters, smart air-conditioner (AC) units, and electric vehicles We use an NREL optimization model to explore the customer-side economics of solar plus under various utility rate structures and net metering rates. We explore optimal solar plus applications in five case studies with different net metering rates and rate structures. The model deploys different configurations of PV, batteries, smart domesticmore » water heaters, and smart AC units in response to different rate structures and customer load profiles. The results indicate that solar plus improves the customer economics of PV and may mitigate some of the negative impacts of evolving rate structures on PV economics. Solar plus may become an increasingly viable model for optimizing PV customer economics in an evolving rate environment.« less

Composite prognostic models across the non-alcoholic fatty liver disease spectrum: Clinical application in developing countries

PubMed Central

Lückhoff, Hilmar K; Kruger, Frederik C; Kotze, Maritha J

2015-01-01

Heterogeneity in clinical presentation, histological severity, prognosis and therapeutic outcomes characteristic of non-alcoholic fatty liver disease (NAFLD) necessitates the development of scientifically sound classification schemes to assist clinicians in stratifying patients into meaningful prognostic subgroups. The need for replacement of invasive liver biopsies as the standard method whereby NAFLD is diagnosed, graded and staged with biomarkers of histological severity injury led to the development of composite prognostic models as potentially viable surrogate alternatives. In the present article, we review existing scoring systems used to (1) confirm the presence of undiagnosed hepatosteatosis; (2) distinguish between simple steatosis and NASH; and (3) predict advanced hepatic fibrosis, with particular emphasis on the role of NAFLD as an independent cardio-metabolic risk factor. In addition, the incorporation of functional genomic markers and application of emerging imaging technologies are discussed as a means to improve the diagnostic accuracy and predictive performance of promising composite models found to be most appropriate for widespread clinical adoption. PMID:26019735

Vibroacoustic test plan evaluation: Parameter variation study

NASA Technical Reports Server (NTRS)

Stahle, C. V.; Gongloef, H. R.

1976-01-01

Statistical decision models are shown to provide a viable method of evaluating the cost effectiveness of alternate vibroacoustic test plans and the associated test levels. The methodology developed provides a major step toward the development of a realistic tool to quantitatively tailor test programs to specific payloads. Testing is considered at the no test, component, subassembly, or system level of assembly. Component redundancy and partial loss of flight data are considered. Most and probabilistic costs are considered, and incipient failures resulting from ground tests are treated. Optimums defining both component and assembly test levels are indicated for the modified test plans considered. modeling simplifications must be considered in interpreting the results relative to a particular payload. New parameters introduced were a no test option, flight by flight failure probabilities, and a cost to design components for higher vibration requirements. Parameters varied were the shuttle payload bay internal acoustic environment, the STS launch cost, the component retest/repair cost, and the amount of redundancy in the housekeeping section of the payload reliability model.

Make dark matter charged again

NASA Astrophysics Data System (ADS)

Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub

2017-05-01

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model.

Uptake and transcytosis of functionalized superparamagnetic iron oxide nanoparticles in an in vitro blood brain barrier model.

PubMed

Ivask, Angela; Pilkington, Emily H; Blin, Thomas; Käkinen, Aleksandr; Vija, Heiki; Visnapuu, Meeri; Quinn, John F; Whittaker, Michael R; Qiao, Ruirui; Davis, Thomas P; Ke, Pu Chun; Voelcker, Nicolas H

2018-01-30

Two major hurdles in nanomedicine are the limited strategies for synthesizing stealth nanoparticles and the poor efficacy of the nanoparticles in translocating across the blood brain barrier (BBB). Here we examined the uptake and transcytosis of iron oxide nanoparticles (IONPs) grafted with biomimetic phosphorylcholine (PC) brushes in an in vitro BBB model system, and compared them with bare, PEG or PC-PEG mixture grafted IONPs. Hyperspectral imaging indicated IONP co-localization with cells. Quantitative analysis with total reflection X-ray fluorescence spectrometry showed that after 24 h, 78% of PC grafted, 68-69% of PEG or PC-PEG grafted, and 30% of bare IONPs were taken up by the BBB. Transcytosis of IONPs was time-dependent and after 24 h, 16-17% of PC or PC-PEG mixture grafted IONPs had passed the BBB model, significantly more than PEG grafted or bare IONPs. These findings point out that grafting of IONPs with PC is a viable strategy for improving the uptake and transcytosis of nanoparticles.

The reconstruction of f(ϕ)R and mimetic gravity from viable slow-roll inflation

NASA Astrophysics Data System (ADS)

Odintsov, S. D.; Oikonomou, V. K.

2018-04-01

In this work, we extend the bottom-up reconstruction framework of F (R) gravity to other modified gravities, and in particular for f (ϕ) R and mimetic F (R) gravities. We investigate which are the important conditions in order for the method to work, and we study several viable cosmological evolutions, focusing on the inflationary era. Particularly, for the f (ϕ) R theory case, we specify the functional form of the Hubble rate and of the scalar-to-tensor ratio as a function of the e-foldings number and accordingly, the rest of the physical quantities and also the slow-roll and the corresponding observational indices can be calculated. The same method is applied in the mimetic F (R) gravity case, and in both cases we thoroughly analyze the resulting free parameter space, in order to show that the viability of the models presented is guaranteed and secondly that there is a wide range of values of the free parameters for which the viability of the models occurs. In addition, the reconstruction method is also studied in the context of mimetic F (R) = R gravity. As we demonstrate, the resulting theory is viable, and also in this case, only the scalar-to-tensor ratio needs to be specified, since the rest follow from this condition. Finally, we discuss in brief how the reconstruction method could function for other modified gravities.

Extinction-effective population index: incorporating life-history variations in population viability analysis.

PubMed

Fujiwara, Masami

2007-09-01

Viability status of populations is a commonly used measure for decision-making in the management of populations. One of the challenges faced by managers is the need to consistently allocate management effort among populations. This allocation should in part be based on comparison of extinction risks among populations. Unfortunately, common criteria that use minimum viable population size or count-based population viability analysis (PVA) often do not provide results that are comparable among populations, primarily because they lack consistency in determining population size measures and threshold levels of population size (e.g., minimum viable population size and quasi-extinction threshold). Here I introduce a new index called the "extinction-effective population index," which accounts for differential effects of demographic stochasticity among organisms with different life-history strategies and among individuals in different life stages. This index is expected to become a new way of determining minimum viable population size criteria and also complement the count-based PVA. The index accounts for the difference in life-history strategies of organisms, which are modeled using matrix population models. The extinction-effective population index, sensitivity, and elasticity are demonstrated in three species of Pacific salmonids. The interpretation of the index is also provided by comparing them with existing demographic indices. Finally, a measure of life-history-specific effect of demographic stochasticity is derived.

Modeling the Jovian aurora

NASA Technical Reports Server (NTRS)

Waite, J. Hunter, Jr.

1992-01-01

The Jovian aurora is the most powerful aurora in the solar system, over 100 times more powerful than the Earth's aurora. These magnificent visual displays can provide important information about the planetary magnetosphere which is responsible for the acceleration of energetic particles that produce aurora at any planet. Similarities and differences in planetary auroral emissions are thus a viable means of classifying and studying both comparative atmospheric and magnetospheric processes. For instance, at Earth the solar wind is the primary source of auroral power while at Jupiter it is conjectured that the rotation of the planet is the major source of magnetospheric and auroral power. The purpose of this IR project was to develop a model: (1) for use in interpreting the existing set of multispectral observations of Jupiter's aurora; and (2) to design new experiments based on the findings to improve understanding of the underlying auroral processes.

COAGULATION CALCULATIONS OF ICY PLANET FORMATION AT 15-150 AU: A CORRELATION BETWEEN THE MAXIMUM RADIUS AND THE SLOPE OF THE SIZE DISTRIBUTION FOR TRANS-NEPTUNIAN OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenyon, Scott J.; Bromley, Benjamin C., E-mail: skenyon@cfa.harvard.edu, E-mail: bromley@physics.utah.edu

2012-03-15

We investigate whether coagulation models of planet formation can explain the observed size distributions of trans-Neptunian objects (TNOs). Analyzing published and new calculations, we demonstrate robust relations between the size of the largest object and the slope of the size distribution for sizes 0.1 km and larger. These relations yield clear, testable predictions for TNOs and other icy objects throughout the solar system. Applying our results to existing observations, we show that a broad range of initial disk masses, planetesimal sizes, and fragmentation parameters can explain the data. Adding dynamical constraints on the initial semimajor axis of 'hot' Kuiper Beltmore » objects along with probable TNO formation times of 10-700 Myr restricts the viable models to those with a massive disk composed of relatively small (1-10 km) planetesimals.« less

From the genome sequence to the protein inventory of Bacillus subtilis.

PubMed

Becher, Dörte; Büttner, Knut; Moche, Martin; Hessling, Bernd; Hecker, Michael

2011-08-01

Owing to the low number of proteins necessary to render a bacterial cell viable, bacteria are extremely attractive model systems to understand how the genome sequence is translated into actual life processes. One of the most intensively investigated model organisms is Bacillus subtilis. It has attracted world-wide research interest, addressing cell differentiation and adaptation on a molecular scale as well as biotechnological production processes. Meanwhile, we are looking back on more than 25 years of B. subtilis proteomics. A wide range of methods have been developed during this period for the large-scale qualitative and quantitative proteome analysis. Currently, it is possible to identify and quantify more than 50% of the predicted proteome in different cellular subfractions. In this review, we summarize the development of B. subtilis proteomics during the past 25 years. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using entropy measures to characterize human locomotion.

PubMed

Leverick, Graham; Szturm, Tony; Wu, Christine Q

2014-12-01

Entropy measures have been widely used to quantify the complexity of theoretical and experimental dynamical systems. In this paper, the value of using entropy measures to characterize human locomotion is demonstrated based on their construct validity, predictive validity in a simple model of human walking and convergent validity in an experimental study. Results show that four of the five considered entropy measures increase meaningfully with the increased probability of falling in a simple passive bipedal walker model. The same four entropy measures also experienced statistically significant increases in response to increasing age and gait impairment caused by cognitive interference in an experimental study. Of the considered entropy measures, the proposed quantized dynamical entropy (QDE) and quantization-based approximation of sample entropy (QASE) offered the best combination of sensitivity to changes in gait dynamics and computational efficiency. Based on these results, entropy appears to be a viable candidate for assessing the stability of human locomotion.

Micro-PIV Study of Supercritical CO2-Water Interactions in Porous Micromodels

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

2015-11-01

Multiphase flow of immiscible fluids in porous media is encountered in numerous natural systems and engineering applications such as enhanced oil recovery (EOR), and CO2 sequestration among others. Geological sequestration of CO2 in saline aquifers has emerged as a viable option for reducing CO2 emissions, and thus it has been the subject of numerous studies in recent years. A key objective is improving the accuracy of numerical models used for field-scale simulations by incorporation/better representation of the pore-scale flow physics. This necessitates experimental data for developing, testing and validating such models. We have studied drainage and imbibition processes in a homogeneous, two-dimensional porous micromodel with CO2 and water at reservoir-relevant conditions. Microscopic particle image velocimetry (micro-PIV) technique was applied to obtain spatially- and temporally-resolved velocity vector fields in the aqueous phase. The results provide new insight into the flow processes at the pore scale.

Using Simulation to Model Improvements in Pediatric Bed Placement in an Acute Care Hospital.

PubMed

Lambton, Judith; Roeder, Theresa; Saltzman, Robert; Param, Lila; Fernandes, Roxanne

2017-02-01

The objective of this project was to use an interdisciplinary approach to analyze strategies through simulation technology for improving patient flow in a pediatric hospital. Various statistics have been offered on the number of children admitted annually to hospitals. For administrators, particularly in smaller systems, the financial burden of equipping and staffing pediatric units often outweighs the moral desire to maintain a pediatric unit as a viable option for patients and pediatricians. Discrete event simulation was used to model current operations of a pediatric unit. Cost analysis was conducted using simulation reflecting various percentages of patients being referred to a discharge holding area (DHA) upon discharge and of the use of all private rooms. Both DHA and private rooms resulted in increased patient volumes. Administrators should consider the use of a DHA and/or private rooms to ease the census strains of pediatric units and the resultant revenue of this service.

Advanced Computational Modeling Approaches for Shock Response Prediction

NASA Technical Reports Server (NTRS)

Derkevorkian, Armen; Kolaini, Ali R.; Peterson, Lee

2015-01-01

Motivation: (1) The activation of pyroshock devices such as explosives, separation nuts, pin-pullers, etc. produces high frequency transient structural response, typically from few tens of Hz to several hundreds of kHz. (2) Lack of reliable analytical tools makes the prediction of appropriate design and qualification test levels a challenge. (3) In the past few decades, several attempts have been made to develop methodologies that predict the structural responses to shock environments. (4) Currently, there is no validated approach that is viable to predict shock environments overt the full frequency range (i.e., 100 Hz to 10 kHz). Scope: (1) Model, analyze, and interpret space structural systems with complex interfaces and discontinuities, subjected to shock loads. (2) Assess the viability of a suite of numerical tools to simulate transient, non-linear solid mechanics and structural dynamics problems, such as shock wave propagation.

Flexible Manufacturing System Handbook. Volume IV. Appendices

DTIC Science & Technology

1983-02-01

and Acceptance Test(s)" on page 26 of this Proposal Request. 1.1.10 Options 1. Centralized Automatic Chip/Coolant Recovery System a. Scope The...viable, from manual- ly moving the pallet/fixture/part combinations from machine to machine to fully automatic , unmanned material handling systems , such...English. Where dimensions are shown in metric units, the English system (inch) equivalent will also be shown. Hydraulic, pneumatic , and electrical

Channel Modeling of Miniaturized Battery-Powered Capacitive Human Body Communication Systems.

PubMed

Park, Jiwoong; Garudadri, Harinath; Mercier, Patrick P

2017-02-01

The purpose of this contribution is to estimate the path loss of capacitive human body communication (HBC) systems under practical conditions. Most prior work utilizes large grounded instruments to perform path loss measurements, resulting in overly optimistic path loss estimates for wearable HBC devices. In this paper, small battery-powered transmitter and receiver devices are implemented to measure path loss under realistic assumptions. A hybrid electrostatic finite element method simulation model is presented that validates measurements and enables rapid and accurate characterization of future capacitive HBC systems. Measurements from form-factor-accurate prototypes reveal path loss results between 31.7 and 42.2 dB from 20 to 150 MHz. Simulation results matched measurements within 2.5 dB. Comeasurements using large grounded benchtop vector network analyzer (VNA) and large battery-powered spectrum analyzer (SA) underestimate path loss by up to 33.6 and 8.2 dB, respectively. Measurements utilizing a VNA with baluns, or large battery-powered SAs with baluns still underestimate path loss by up to 24.3 and 6.7 dB, respectively. Measurements of path loss in capacitive HBC systems strongly depend on instrumentation configurations. It is thus imperative to simulate or measure path loss in capacitive HBC systems utilizing realistic geometries and grounding configurations. HBC has a great potential for many emerging wearable devices and applications; accurate path loss estimation will improve system-level design leading to viable products.

Re-engineering NASA's space communications to remain viable in a constrained fiscal environment

NASA Astrophysics Data System (ADS)

Hornstein, Rhoda Shaller; Hei, Donald J., Jr.; Kelly, Angelita C.; Lightfoot, Patricia C.; Bell, Holland T.; Cureton-Snead, Izeller E.; Hurd, William J.; Scales, Charles H.

1994-11-01

Along with the Red and Blue Teams commissioned by the NASA Administrator in 1992, NASA's Associate Administrator for Space Communications commissioned a Blue Team to review the Office of Space Communications (Code O) Core Program and determine how the program could be conducted faster, better, and cheaper. Since there was no corresponding Red Team for the Code O Blue Team, the Blue Team assumed a Red Team independent attitude and challenged the status quo, including current work processes, functional distinctions, interfaces, and information flow, as well as traditional management and system development practices. The Blue Team's unconstrained, non-parochial, and imaginative look at NASA's space communications program produced a simplified representation of the space communications infrastructure that transcends organizational and functional boundaries, in addition to existing systems and facilities. Further, the Blue Team adapted the 'faster, better, cheaper' charter to be relevant to the multi-mission, continuous nature of the space communications program and to serve as a gauge for improving customer services concurrent with achieving more efficient operations and infrastructure life cycle economies. This simplified representation, together with the adapted metrics, offers a future view and process model for reengineering NASA's space communications to remain viable in a constrained fiscal environment. Code O remains firm in its commitment to improve productivity, effectiveness, and efficiency. In October 1992, the Associate Administrator reconstituted the Blue Team as the Code O Success Team (COST) to serve as a catalyst for change. In this paper, the COST presents the chronicle and significance of the simplified representation and adapted metrics, and their application during the FY 1993-1994 activities.

Re-engineering NASA's space communications to remain viable in a constrained fiscal environment

NASA Technical Reports Server (NTRS)

Hornstein, Rhoda Shaller; Hei, Donald J., Jr.; Kelly, Angelita C.; Lightfoot, Patricia C.; Bell, Holland T.; Cureton-Snead, Izeller E.; Hurd, William J.; Scales, Charles H.

1994-01-01

Along with the Red and Blue Teams commissioned by the NASA Administrator in 1992, NASA's Associate Administrator for Space Communications commissioned a Blue Team to review the Office of Space Communications (Code O) Core Program and determine how the program could be conducted faster, better, and cheaper. Since there was no corresponding Red Team for the Code O Blue Team, the Blue Team assumed a Red Team independent attitude and challenged the status quo, including current work processes, functional distinctions, interfaces, and information flow, as well as traditional management and system development practices. The Blue Team's unconstrained, non-parochial, and imaginative look at NASA's space communications program produced a simplified representation of the space communications infrastructure that transcends organizational and functional boundaries, in addition to existing systems and facilities. Further, the Blue Team adapted the 'faster, better, cheaper' charter to be relevant to the multi-mission, continuous nature of the space communications program and to serve as a gauge for improving customer services concurrent with achieving more efficient operations and infrastructure life cycle economies. This simplified representation, together with the adapted metrics, offers a future view and process model for reengineering NASA's space communications to remain viable in a constrained fiscal environment. Code O remains firm in its commitment to improve productivity, effectiveness, and efficiency. In October 1992, the Associate Administrator reconstituted the Blue Team as the Code O Success Team (COST) to serve as a catalyst for change. In this paper, the COST presents the chronicle and significance of the simplified representation and adapted metrics, and their application during the FY 1993-1994 activities.

Modeling, simulation, and flight characteristics of an aircraft designed to fly at 100,000 feet

NASA Technical Reports Server (NTRS)

Sim, Alex G.

1991-01-01

A manned real time simulation of a conceptual vehicle, the stratoplane, was developed to study the problems associated with the flight characteristics of a large, lightweight vehicle. Mathematical models of the aerodynamics, mass properties, and propulsion system were developed in support of the simulation and are presented. The simulation was at first conducted without control augmentation to determine the needs for a control system. The unaugmented flying qualities were dominated by lightly damped dutch roll oscillations. Constant pilot workloads were needed at high altitudes. Control augmentation was studied using basic feedbacks. For the longitudinal axis, flight path angle, and pitch rate feedback were sufficient to damp the phugoid mode and to provide good flying qualities. In the lateral directional axis, bank angle, roll rate, and yaw rate feedbacks were sufficient to provide a safe vehicle with acceptable handling qualities. Intentionally stalling the stratoplane to very high angles of attack (deep stall) was studied as a means of enable safe and rapid descent. It was concluded that the deep stall maneuver is viable for this class of vehicle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grondein, P.; Lafleur, T.; Chabert, P.

Most state-of-the-art electric space propulsion systems such as gridded and Hall effect thrusters use xenon as the propellant gas. However, xenon is very rare, expensive to produce, and used in a number of competing industrial applications. Alternatives to xenon are currently being investigated, and iodine has emerged as a potential candidate. Its lower cost and larger availability, its solid state at standard temperature and pressure, its low vapour pressure and its low ionization potential make it an attractive option. In this work, we compare the performances of a gridded ion thruster operating separately with iodine and xenon, under otherwise identicalmore » conditions using a global model. The thruster discharge properties such as neutral, ion, and electron densities and electron temperature are calculated, as well as the thruster performance parameters such as thrust, specific impulse, and system efficiencies. For similar operating conditions, representative of realistic thrusters, the model predicts similar thrust levels and performances for both iodine and xenon. The thruster efficiency is however slightly higher for iodine compared with xenon, due to its lower ionization potential. This demonstrates that iodine could be a viable alternative propellant for gridded plasma thrusters.« less

Developing technologies for bioacoustic vocal profiling as a viable component of integrative medical diagnostics and treatment

NASA Astrophysics Data System (ADS)

Edwards, Sharry K.

2005-04-01

Over the past 20+ years the pioneering field of Human Bioacoustics, which includes voice spectral analysis, has begun to model the frequencies and architecture of human vocalizations to identify the innate mathematical templates found within the various system of the human body. Using the idea that the voice is a holographic representation of health and wellness, these non-invasive techniques are being advanced to the extent that a computerized Vocal Profile, using a system of Frequency Equivalents, can be used to accurately quantify, organize, interpret, define, and extrapolate biometric information from the human voice. This information, in turn, provides the opportunity to predict, direct, and maintain intrinsic form and function. This novel approach has provided an accumulation of significant data but until recently has been without an efficient biological framework of reference. The emerging Mathematical Model being assembled through Human Bioacoustic research likely has the potential to allow Vocal Profiling to be used to predict and monitor health issues from the very first cries of a newborn through the frequency foundations of disease and aging.

Commercial launch systems: A risky investment?

NASA Astrophysics Data System (ADS)

Dupnick, Edwin; Skratt, John

1996-03-01

A myriad of evolutionary paths connect the current state of government-dominated space launch operations to true commercial access to space. Every potential path requires the investment of private capital sufficient to fund the commercial venture with a perceived risk/return ratio acceptable to the investors. What is the private sector willing to invest? Does government participation reduce financial risk? How viable is a commercial launch system without government participation and support? We examine the interplay between various forms of government participation in commercial launch system development, alternative launch system designs, life cycle cost estimates, and typical industry risk aversion levels. The boundaries of this n-dimensional envelope are examined with an ECON-developed business financial model which provides for the parametric assessment and interaction of SSTO design variables (including various operational scenarios with financial variables including debt/equity assumptions, and commercial enterprise burden rates on various functions. We overlay this structure with observations from previous ECON research which characterize financial risk aversion levels for selected industrial sectors in terms of acceptable initial lump-sum investments, cumulative investments, probability of failure, payback periods, and ROI. The financial model allows the construction of parametric tradeoffs based on ranges of variables which can be said to actually encompass the ``true'' cost of operations and determine what level of ``true'' costs can be tolerated by private capitalization.

Three-dimensional Myoblast Aggregates--Effects of Modeled Microgravity

NASA Technical Reports Server (NTRS)

Byerly, Diane; Sognier, M. A.; Marquette, M. L.

2006-01-01

The overall objective of these studies is to elucidate the molecular and cellular alterations that contribute to muscle atrophy in astronauts caused by exposure to microgravity conditions in space. To accomplish this, a three-dimensional model test system was developed using mouse myoblast cells (C2C12). Myoblast cells were grown as three-dimensional aggregates (without scaffolding or other solid support structures) in both modeled microgravity (Rotary Cell Culture System, Synthecon, Inc.) and at unit gravity in coated Petri dishes. Evaluation of H&E stained thin sections of the aggregates revealed the absence of any necrosis. Confocal microscopy evaluations of cells stained with the Live/Dead assay (Molecular Probes) confirmed that viable cells were present throughout the aggregates with an average of only three dead cells observed per aggregate. Preliminary results from gene array analysis (Affymetrix chip U74Av2) showed that approximately 14% of the genes were down regulated (decreased more than 3 fold) and 4% were upregulated in cells exposed to modeled microgravity for 12 hours compared to unit gravity controls. Additional studies using fluorescent phallacidin revealed a decrease in F-actin in the cells exposed to modeled microgravity compared to unit gravity. Myoblast cells grown as aggregates in modeled microgravity exhibited spontaneous differentiation into syncitia while no differentiation was seen in the unit gravity controls. These studies show that 1)the model test system developed is suitable for assessing cellular and molecular alterations in myoblasts; 2) gene expression alterations occur rapidly (within 12 hours) following exposure to modeled microgravity; and 3) modeled microgravity conditions stimulated myoblast cell differentiation. Achieving a greater understanding of the molecular alterations leading to muscle atrophy will eventually enable the development of cell-based countermeasures, which may be valuable for treatment of muscle diseases on Earth and future space explorations.

Dendrimer brain uptake and targeted therapy for brain injury in a large animal model of hypothermic circulatory arrest.

PubMed

Mishra, Manoj K; Beaty, Claude A; Lesniak, Wojciech G; Kambhampati, Siva P; Zhang, Fan; Wilson, Mary A; Blue, Mary E; Troncoso, Juan C; Kannan, Sujatha; Johnston, Michael V; Baumgartner, William A; Kannan, Rangaramanujam M

2014-03-25

Treatment of brain injury following circulatory arrest is a challenging health issue with no viable therapeutic options. Based on studies in a clinically relevant large animal (canine) model of hypothermic circulatory arrest (HCA)-induced brain injury, neuroinflammation and excitotoxicity have been identified as key players in mediating the brain injury after HCA. Therapy with large doses of valproic acid (VPA) showed some neuroprotection but was associated with adverse side effects. For the first time in a large animal model, we explored whether systemically administered polyamidoamine (PAMAM) dendrimers could be effective in reaching target cells in the brain and deliver therapeutics. We showed that, upon systemic administration, hydroxyl-terminated PAMAM dendrimers are taken up in the brain of injured animals and selectively localize in the injured neurons and microglia in the brain. The biodistribution in other major organs was similar to that seen in small animal models. We studied systemic dendrimer-drug combination therapy with two clinically approved drugs, N-acetyl cysteine (NAC) (attenuating neuroinflammation) and valproic acid (attenuating excitotoxicity), building on positive outcomes in a rabbit model of perinatal brain injury. We prepared and characterized dendrimer-NAC (D-NAC) and dendrimer-VPA (D-VPA) conjugates in multigram quantities. A glutathione-sensitive linker to enable for fast intracellular release. In preliminary efficacy studies, combination therapy with D-NAC and D-VPA showed promise in this large animal model, producing 24 h neurological deficit score improvements comparable to high dose combination therapy with VPA and NAC, or free VPA, but at one-tenth the dose, while significantly reducing the adverse side effects. Since adverse side effects of drugs are exaggerated in HCA, the reduced side effects with dendrimer conjugates and suggestions of neuroprotection offer promise for these nanoscale drug delivery systems.

Dendrimer Brain Uptake and Targeted Therapy for Brain Injury in a Large Animal Model of Hypothermic Circulatory Arrest

PubMed Central

2015-01-01

Treatment of brain injury following circulatory arrest is a challenging health issue with no viable therapeutic options. Based on studies in a clinically relevant large animal (canine) model of hypothermic circulatory arrest (HCA)-induced brain injury, neuroinflammation and excitotoxicity have been identified as key players in mediating the brain injury after HCA. Therapy with large doses of valproic acid (VPA) showed some neuroprotection but was associated with adverse side effects. For the first time in a large animal model, we explored whether systemically administered polyamidoamine (PAMAM) dendrimers could be effective in reaching target cells in the brain and deliver therapeutics. We showed that, upon systemic administration, hydroxyl-terminated PAMAM dendrimers are taken up in the brain of injured animals and selectively localize in the injured neurons and microglia in the brain. The biodistribution in other major organs was similar to that seen in small animal models. We studied systemic dendrimer–drug combination therapy with two clinically approved drugs, N-acetyl cysteine (NAC) (attenuating neuroinflammation) and valproic acid (attenuating excitotoxicity), building on positive outcomes in a rabbit model of perinatal brain injury. We prepared and characterized dendrimer-NAC (D-NAC) and dendrimer-VPA (D-VPA) conjugates in multigram quantities. A glutathione-sensitive linker to enable for fast intracellular release. In preliminary efficacy studies, combination therapy with D-NAC and D-VPA showed promise in this large animal model, producing 24 h neurological deficit score improvements comparable to high dose combination therapy with VPA and NAC, or free VPA, but at one-tenth the dose, while significantly reducing the adverse side effects. Since adverse side effects of drugs are exaggerated in HCA, the reduced side effects with dendrimer conjugates and suggestions of neuroprotection offer promise for these nanoscale drug delivery systems. PMID:24499315

A Bayesian Machine Learning Model for Estimating Building Occupancy from Open Source Data

DOE PAGES

Stewart, Robert N.; Urban, Marie L.; Duchscherer, Samantha E.; ...

2016-01-01

Understanding building occupancy is critical to a wide array of applications including natural hazards loss analysis, green building technologies, and population distribution modeling. Due to the expense of directly monitoring buildings, scientists rely in addition on a wide and disparate array of ancillary and open source information including subject matter expertise, survey data, and remote sensing information. These data are fused using data harmonization methods which refer to a loose collection of formal and informal techniques for fusing data together to create viable content for building occupancy estimation. In this paper, we add to the current state of the artmore » by introducing the Population Data Tables (PDT), a Bayesian based informatics system for systematically arranging data and harmonization techniques into a consistent, transparent, knowledge learning framework that retains in the final estimation uncertainty emerging from data, expert judgment, and model parameterization. PDT probabilistically estimates ambient occupancy in units of people/1000ft2 for over 50 building types at the national and sub-national level with the goal of providing global coverage. The challenge of global coverage led to the development of an interdisciplinary geospatial informatics system tool that provides the framework for capturing, storing, and managing open source data, handling subject matter expertise, carrying out Bayesian analytics as well as visualizing and exporting occupancy estimation results. We present the PDT project, situate the work within the larger community, and report on the progress of this multi-year project.Understanding building occupancy is critical to a wide array of applications including natural hazards loss analysis, green building technologies, and population distribution modeling. Due to the expense of directly monitoring buildings, scientists rely in addition on a wide and disparate array of ancillary and open source information including subject matter expertise, survey data, and remote sensing information. These data are fused using data harmonization methods which refer to a loose collection of formal and informal techniques for fusing data together to create viable content for building occupancy estimation. In this paper, we add to the current state of the art by introducing the Population Data Tables (PDT), a Bayesian model and informatics system for systematically arranging data and harmonization techniques into a consistent, transparent, knowledge learning framework that retains in the final estimation uncertainty emerging from data, expert judgment, and model parameterization. PDT probabilistically estimates ambient occupancy in units of people/1000 ft 2 for over 50 building types at the national and sub-national level with the goal of providing global coverage. The challenge of global coverage led to the development of an interdisciplinary geospatial informatics system tool that provides the framework for capturing, storing, and managing open source data, handling subject matter expertise, carrying out Bayesian analytics as well as visualizing and exporting occupancy estimation results. We present the PDT project, situate the work within the larger community, and report on the progress of this multi-year project.« less

Tension stimulation drives tissue formation in scaffold-free systems

NASA Astrophysics Data System (ADS)

Lee, Jennifer K.; Huwe, Le W.; Paschos, Nikolaos; Aryaei, Ashkan; Gegg, Courtney A.; Hu, Jerry C.; Athanasiou, Kyriacos A.

2017-08-01

Scaffold-free systems have emerged as viable approaches for engineering load-bearing tissues. However, the tensile properties of engineered tissues have remained far below the values for native tissue. Here, by using self-assembled articular cartilage as a model to examine the effects of intermittent and continuous tension stimulation on tissue formation, we show that the application of tension alone, or in combination with matrix remodelling and synthesis agents, leads to neocartilage with tensile properties approaching those of native tissue. Implantation of tension-stimulated tissues results in neotissues that are morphologically reminiscent of native cartilage. We also show that tension stimulation can be translated to a human cell source to generate anisotropic human neocartilage with enhanced tensile properties. Tension stimulation, which results in nearly sixfold improvements in tensile properties over unstimulated controls, may allow the engineering of mechanically robust biological replacements of native tissue.

Strategic Technology Investment Analysis: An Integrated System Approach

NASA Technical Reports Server (NTRS)

Adumitroaie, V.; Weisbin, C. R.

2010-01-01

Complex technology investment decisions within NASA are increasingly difficult to make such that the end results are satisfying the technical objectives and all the organizational constraints. Due to a restricted science budget environment and numerous required technology developments, the investment decisions need to take into account not only the functional impact on the program goals, but also development uncertainties and cost variations along with maintaining a healthy workforce. This paper describes an approach for optimizing and qualifying technology investment portfolios from the perspective of an integrated system model. The methodology encompasses multi-attribute decision theory elements and sensitivity analysis. The evaluation of the degree of robustness of the recommended portfolio provides the decision-maker with an array of viable selection alternatives, which take into account input uncertainties and possibly satisfy nontechnical constraints. The methodology is presented in the context of assessing capability development portfolios for NASA technology programs.

Stem cell-extracellular vesicles as drug delivery systems: New frontiers for silk/curcumin nanoparticles.

PubMed

Perteghella, Sara; Crivelli, Barbara; Catenacci, Laura; Sorrenti, Milena; Bruni, Giovanna; Necchi, Vittorio; Vigani, Barbara; Sorlini, Marzio; Torre, Maria Luisa; Chlapanidas, Theodora

2017-03-30

The aim of this work was to develop a novel carrier-in-carrier system based on stem cell-extracellular vesicles loaded of silk/curcumin nanoparticles by endogenous technique. Silk nanoparticles were produced by desolvation method and curcumin has been selected as drug model because of its limited water solubility and poor bioavailability. Nanoparticles were stable, with spherical geometry, 100nm in average diameter and the drug content reached about 30%. Cellular uptake studies, performed on mesenchymal stem cells (MSCs), showed the accumulation of nanoparticles in the cytosol around the nuclear membrane, without cytotoxic effects. Finally, MSCs were able to release extracellular vesicles entrapping silk/curcumin nanoparticles. This combined biological-technological approach represents a novel class of nanosystems, combining beneficial effects of both regenerative cell therapies and pharmaceutical nanomedicine, avoiding the use of viable replicating stem cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Functional nicotinic acetylcholine receptor reconstitution in Au(111)-supported thiolipid monolayers

NASA Astrophysics Data System (ADS)

Pissinis, Diego E.; Diaz, Carolina; Maza, Eliana; Bonini, Ida C.; Barrantes, Francisco J.; Salvarezza, Roberto C.; Schilardi, Patricia L.

2015-09-01

The insertion and function of the muscle-type nicotinic acetylcholine receptor (nAChR) in Au(111)-supported thiolipid self-assembled monolayers have been studied by atomic force microscopy (AFM), surface plasmon resonance (SPR), and electrochemical techniques. It was possible for the first time to resolve the supramolecular arrangement of the protein spontaneously inserted in a thiolipid monolayer in an aqueous solution. Geometric supramolecular arrays of nAChRs were observed, most commonly in a triangular form compatible with three nAChR dimers of ~20 nm each. Addition of the full agonist carbamoylcholine activated and opened the nAChR ion channel, as revealed by the increase in capacitance relative to that of the nAChR-thiolipid system under basal conditions. Thus, the self-assembled system appears to be a viable biomimetic model to measure ionic conductance mediated by ion-gated ion channels under different experimental conditions, with potential applications in biotechnology and pharmacology.

Primordial heating of asteroidal parent bodies

NASA Technical Reports Server (NTRS)

Sonett, C. P.; Reynolds, R. T.

1979-01-01

Most meteorites show evidence of thermal processing either because of metamorphic changes or as a result of melting and differentiation. Proposed mechanisms for supplying this energy generally rely upon short-lived radioisotopes or electrical induction, though accretion is sometimes mentioned, and more exotic models have been discussed. Interest in isotopic heating has been heightened by the discovery of Al-26 in Allende inclusions and also by the proposal that a lunar core and dynamo resulted from the radioactive decay of superheavy elements during the early solar system. Electrical induction as a heat source can be scaled to a broad range of solar system conditions, but corroborative evidence for these conditions is inconclusive. The accretion mechanism is probably not viable for the asteroidal and meteorite parent bodies, because the high kinetic energy requirement is inconsistent with the formation of the objects and their regoliths in the presence of a weak gravitational field.

Development and evaluation of a reflective solar disinfection pouch for treatment of drinking water.

PubMed

Walker, D Carey; Len, Soo-Voon; Sheehan, Brita

2004-04-01

A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles. The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period. These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials.

Synthesis of long Prebiotic Oligomers on Mineral Surfaces

NASA Technical Reports Server (NTRS)

Ferris, James P.; Hill, Aubrey R., Jr.; Liu, Rihe; Orgel, Leslie E.

1996-01-01

Most theories of the origin of biological organization assume that polymers with lengths in the range of 30-60 monomers are needed to make a genetic system viable. But it has not proved possible to synthesize plausibly prebiotic polymers this long by condensation in aqueous solution, because hydrolysis competes with polymerization. The potential of mineral surfaces to facilitate prebiotic polymerization was pointed out long ago. Here we describe a system that models prebiotic polymerization by the oligomerization of activated monomers -both nucleotides and amino acids. We find that whereas the reactions in solution produce only short oligomers (the longest typically being a 10-mer), the presence of mineral surfaces (montmorillonite for nucleotides, illite and hydroxylapatite for amino adds) induces the formation of oligomers up to 55 monomers long. These are formed by successive "feedings" with the monomers; polymerization takes place on the mineral surfaces in a manner akin to solid-phase synthesis of biopolymers.

Tetrahymena in the laboratory: strain resources, methods for culture, maintenance, and storage.

PubMed

Cassidy-Hanley, Donna M

2012-01-01

The ciliated protozoan Tetrahymena thermophila has been an important model system for biological research for many years. During that time, a variety of useful strains, including highly inbred stocks, a collection of diverse mutant strains, and wild cultivars from a variety of geographical locations have been identified. In addition, thanks to the efforts of many different laboratories, optimal conditions for growth, maintenance, and storage of Tetrahymena have been worked out. To facilitate the efficient use of Tetrahymena, especially by those new to the system, this chapter presents a brief description of many available Tetrahymena strains and lists possible resources for obtaining viable cultures of T. thermophila and other Tetrahymena species. Descriptions of commonly used media, methods for cell culture and maintenance, and protocols for short- and long-term storage are also presented. Copyright © 2012 Elsevier Inc. All rights reserved.

An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation

PubMed Central

Radhakrishnan, Nitin; Park, Jongwon; Kim, Chang-Soo

2012-01-01

Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems. PMID:23012527

Neural network based control of Doubly Fed Induction Generator in wind power generation

NASA Astrophysics Data System (ADS)

Barbade, Swati A.; Kasliwal, Prabha

2012-07-01

To complement the other types of pollution-free generation wind energy is a viable option. Previously wind turbines were operated at constant speed. The evolution of technology related to wind systems industry leaded to the development of a generation of variable speed wind turbines that present many advantages compared to the fixed speed wind turbines. In this paper the phasor model of DFIG is used. This paper presents a study of a doubly fed induction generator driven by a wind turbine connected to the grid, and controlled by artificial neural network ANN controller. The behaviour of the system is shown with PI control, and then as controlled by ANN. The effectiveness of the artificial neural network controller is compared to that of a PI controller. The SIMULINK/MATLAB simulation for Doubly Fed Induction Generator and corresponding results and waveforms are displayed.

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?

NASA Astrophysics Data System (ADS)

Portegies Zwart, S. F.; van den Heuvel, E. P. J.

2016-03-01

We discuss the events that led to the giant eruption of Eta Carinae, and find that the mid-nineteenth century (in 1838-1843) giant mass-loss outburst has the characteristics of being produced by the merger event of a massive close binary, triggered by the gravitational interaction with a massive third companion star, which is the current binary companion in the Eta Carinae system. We come to this conclusion by a combination of theoretical arguments supported by computer simulations using the Astrophysical Multipurpose Software Environment. According to this model the ˜90 M⊙ present primary star of the highly eccentric Eta Carinae binary system is the product of this merger, and its ˜30 M⊙ companion originally was the third star in the system. In our model, the Homunculus nebula was produced by an extremely enhanced stellar wind, energized by tidal energy dissipation prior to the merger, which enormously boosted the radiation-driven wind mass-loss. The current orbital plane is then aligned with the equatorial plane of the Homunculus, and the symmetric lobes are roughly aligned with the argument of periastron of the current Eta Carina binary. The merger itself then occurred in 1838, which resulted in a massive asymmetric outflow in the equatorial plane of the Homunculus. The 1843 outburst can in our model be attributed to the subsequent encounter when the companion star (once the outermost star in the triple system) plunges through the bloated envelope of the merger product, once when it passed periastron again. We predict that the system has an excess space velocity of order 50 km s-1 in the equatorial plane of the Homunculus. Our triple model gives a viable explanation for the high runaway velocities typically observed in LBVs.

Solar energy system economic evaluation for Elcam-Tempe, Tempe, Arizona and Elcam-San Diego, San Diego, California

NASA Technical Reports Server (NTRS)

1980-01-01

The long term economic performance of the solar energy system at its installation site is analyzed and four additional locations selected to demonstrate the viability of the design over a broad range of environmental and economic conditions. The economic analysis of the solar energy systems that were installed at Tempe, Arizona and San Diego, California, is developed for these and four other sites typical of a wide range of environmental and economic conditions in the continental United States. This analysis is accomplished based on the technical and economic models in the f Chart design procedure with inputs based on the characteristics of the installed system and local conditions. The results are expressed in terms of the economic parameters of present worth of system cost over a projected twenty year life: life cycle savings; year of positive savings; and year of payback for the optimized solar energy system at each of the analysis sites. The sensitivity of the economic evaluation to uncertainites in constituent system and economic variables is also investigated. The results demonstrate that the solar energy system is economically viable at all of the sites for which the analysis was conducted.

Noninductive RF startup in CDX-U

NASA Astrophysics Data System (ADS)

Jones, B.; Majeski, R.; Efthimion, P.; Kaita, R.; Menard, J.; Munsat, T.; Takase, Y.

1998-11-01

For the spherical torus (ST) to prove viable as a reactor, it will be necessary to devise techniques for noninductive plasma startup. Initial studies of noninductive plasma initiation have been performed on CDX-U, using the 100 kW high harmonic fast wave (HHFW) system in combination with the 1 kW 2.45 GHz electron cyclotron heating system used for breakdown. Modest density (ne ~ 10^12 cm-3), low temperature (5 eV) plasmas were formed, but the density profile was peaked far off-axis, very near the HHFW antenna. High neutral fill pressures were also required. In upcoming experiments, up to 500 kW of low frequency RF power will utilized for heating and noninductive current drive in the mode conversion regime in a target noninductive plasma formed by a combination of 5.6 and 14 GHz ECH (40 kW total). Modeling will be presented which indicates that startup to plasma currents of 60 kA is feasible with this system.

Statistical mechanics of tuned cell signalling: sensitive collective response by synthetic biological circuits

NASA Astrophysics Data System (ADS)

Voliotis, M.; Liverpool, T. B.

2017-03-01

Living cells sense and process environmental cues through noisy biochemical mechanisms. This apparatus limits the scope of engineering cells as viable sensors. Here, we highlight a mechanism that enables robust, population-wide responses to external stimulation based on cellular communication, known as quorum sensing. We propose a synthetic circuit consisting of two mutually repressing quorum sensing modules. At low cell densities the system behaves like a genetic toggle switch, while at higher cell densities the behaviour of nearby cells is coupled via diffusible quorum sensing molecules. We show by systematic coarse graining that at large length and timescales that the system can be described using the Ising model of a ferromagnet. Thus, in analogy with magnetic systems, the sensitivity of the population-wide response, or its ‘susceptibility’ to a change in the external signal, is highly enhanced for a narrow range of cell-cell coupling close to a critical value. We expect that our approach will be used to enhance the sensitivity of synthetic bio-sensing networks.

Wind-energy recovery by a static Scherbius induction generator

NASA Astrophysics Data System (ADS)

Smith, G. A.; Nigim, K. A.

1981-11-01

The paper describes a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system. The secondary circuit of the generator is supplied at a variable frequency from a current source inverter which for test purposes is rated to allow energy recovery, from a simulated windmill, from maximum speed to standstill. To overcome the stability problems normally associated with doubly fed machines a novel signal generator, which is locked in phase with the rotor EMF, controls the secondary power to provide operation over a wide range of subsynchronous and supersynchronous speeds. Consideration of power flow enables the VA rating of the secondary power source to be determined as a function of the gear ratio and online operating range of the system. A simple current source model is used to predict performance which is compared with experimental results. The results indicate a viable system, and suggestions for further work are proposed.

An alternative resource sharing scheme for land mobile satellite services

NASA Technical Reports Server (NTRS)

Yan, Tsun-Yee; Sue, Miles K.

1990-01-01

A preliminary comparison between the two competing channelization concepts for the Land Mobile Satellite Services (LMSS), namely frequency division (FD) and code division (CD), is presented. Both random access and demand-assigned approaches are considered under these concepts. The CD concept is compared with the traditional FD concept based on the system consideration and a projected traffic model. It is shown that CD is not particularly attractive for the first generation Mobile Satellite Services because of the spectral occupancy of the network bandwidth. However, the CD concept is a viable alternative for future systems such as the personal access satellite system (PASS) in the Ka-band spectrum where spectral efficiency is not of prime concern. The effects of power robbing and voice activity factor are incorporated. It was shown that the traditional rule of thumb of dividing the number of raw channels by the voice activity factor to obtain the effective number of channels is only valid asymptotically as the aggregated traffic approaches infinity.