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Sample records for develop transmission dynamics

  1. Hydatidosis: dynamics of transmission.

    PubMed

    Bourée, P

    2001-01-01

    Hydatidosis is a widespread zoonosis infecting a large number of animals and humans. Echinococcus granulosus has the smallest taenia adult of the cestodes but with the largest larva. Its morphologic and biologic features were identified with DNA analysis. Different strains were separated according to the intermediate hosts: sheep, cattle, pigs, horses, camels. Definitive host are canids, mostly dogs, where the worm grows to adulthood in several months. The eggs are scattered in the pasture by wind and water and are ingested by various hosts. The larvae migrate through the intestinal wall and penetrate the organs, mostly liver and lungs. The eggs survive several days outside, depending on the temperature, but numerous eggs die in nature because they cannot resist desiccation and extreme temperatures. Dissemination is accomplished by dogs. In Turkana (Kenya) the incidence of hydatidosis is high because of the close relationship between the population and dogs and the habit of leaving their dead bodies in the grasslands. In rural areas, the custom of slaughtering sheep at home, among the dogs, is an important dissemination factor. The circumstances of transmission vary according to the country. In Europe the natural life cycle of E. granulosus granulosus involves dogs as the definitive host and sheep as the intermediate host. In northern Europe E. granulosus borealis infects the canids and deer. E. granulosus canadensis infects wolves and reindeer, but there are no human cases. In the endemic Mediterranean area, sheep and dromedaries are the intermediate hosts. In South America, the life cycle of E. granulosus develops among several definitive and intermediate hosts. Hence the dynamics of transmission vary according to the countries with different hosts. PMID:11213154

  2. Dynamic Transmission Electron Microscopy

    SciTech Connect

    Evans, James E.; Jungjohann, K. L.; Browning, Nigel D.

    2012-10-12

    Dynamic transmission electron microscopy (DTEM) combines the benefits of high spatial resolution electron microscopy with the high temporal resolution of ultrafast lasers. The incorporation of these two components into a single instrument provides a perfect platform for in situ observations of material processes. However, previous DTEM applications have focused on observing structural changes occurring in samples exposed to high vacuum. Therefore, in order to expand the pump-probe experimental regime to more natural environmental conditions, in situ gas and liquid chambers must be coupled with Dynamic TEM. This chapter describes the current and future applications of in situ liquid DTEM to permit time-resolved atomic scale observations in an aqueous environment, Although this chapter focuses mostly on in situ liquid imaging, the same research potential exists for in situ gas experiments and the successful integration of these techniques promises new insights for understanding nanoparticle, catalyst and biological protein dynamics with unprecedented spatiotemporal resolution.

  3. Dynamically prioritized progressive transmission

    NASA Astrophysics Data System (ADS)

    Blanford, Ronald

    1992-04-01

    Retrieval of image data from a centralized database may be subject to bandwidth limitations, whether due to a low-bandwidth communications link or to contention from simultaneous accesses over a high-bandwidth link. Progressive transmission can alleviate this problem by encoding image data so that any prefix of the data stream approximates the complete image at a coarse level of resolution. The longer the prefix, the finer the resolution. In many cases, as little at 1 percent of the image data may be sufficient to decide whether to discard the image, to permit the retrieval to continue, or to restrict retrieval to a subsection of the image. Our approach treats resolution not as a fixed attribute of the image, but rather as a resource which may be allocated to portions of the image at the direction of a user-specified priority function. The default priority function minimizes error by allocating more resolution to regions of high variance. The user may also point to regions of interest requesting priority transmission. More advanced target recognition strategies may be incorporated at the user's discretion. Multispectral imagery is supported. The user engineering implications are profounded. There is immediate response to a query that might otherwise take minutes to complete. The data is transmitted in small increments so that no single user dominates the communications bandwidth. The user-directed improvement means that bandwidth is focused on interesting information. The user may continue working with the first coarse approximations while further image data is still arriving. The algorithm has been implemented in C on Sun, Silicon Graphics, and NeXT workstations, and in Lisp on a Symbolics. Transmission speeds reach as high as 60,000 baud using a Sparc or 68040 processor when storing data to memory; somewhat less if also updating a graphical display. The memory requirements are roughly five bytes per image pixel. Both computational and memory costs may be reduced

  4. Long-term effects of penicillin resistance and fitness cost on pneumococcal transmission dynamics in a developed setting

    PubMed Central

    Tilevik, Diana

    2016-01-01

    Background The increasing prevalence of penicillin non-susceptible pneumococci (PNSP) throughout the world threatens successful treatment of infections caused by this important bacterial pathogen. The rate at which PNSP clones spread in the community is thought to mainly be determined by two key determinants; the volume of penicillin use and the magnitude of the fitness cost in the absence of treatment. The aim of the study was to determine the impacts of penicillin consumption and fitness cost on pneumococcal transmission dynamics in a developed country setting. Methods An individual-based network model based on real-life demographic data was constructed and applied in a developed country setting (Sweden). A population structure with transmission of carriage taking place within relevant mixing groups, i.e. families, day care groups, school classes, and other close contacts, was considered to properly assess the transmission dynamics for susceptible and PNSP clones. Several scenarios were simulated and model outcomes were statistically analysed. Results Model simulations predicted that with an outpatient penicillin use corresponding to the sales in Sweden 2010 (118 recipes per 1,000 inhabitants per year), the magnitude of a fitness cost for resistance must be at least 5% to offset the advantage of penicillin resistance. Moreover, even if there is a fitness cost associated with penicillin resistance, a considerable reduction of penicillin usage appears to be required to significantly decrease the incidence of PNSP in a community. Conclusion The frequency of PNSP clones is hard to reverse by simply reducing the penicillin consumption even if there is a biological cost associated with resistance. However, because penicillin usage does promote further spread of PNSP clones, it is important to keep down penicillin consumption considering future resistance problems. PMID:27206408

  5. Global dynamic modeling of a transmission system

    NASA Astrophysics Data System (ADS)

    Choy, F. K.; Qian, W.

    1993-04-01

    The work performed on global dynamic simulation and noise correlation of gear transmission systems at the University of Akron is outlined. The objective is to develop a comprehensive procedure to simulate the dynamics of the gear transmission system coupled with the effects of gear box vibrations. The developed numerical model is benchmarked with results from experimental tests at NASA Lewis Research Center. The modal synthesis approach is used to develop the global transient vibration analysis procedure used in the model. Modal dynamic characteristics of the rotor-gear-bearing system are calculated by the matrix transfer method while those of the gear box are evaluated by the finite element method (NASTRAN). A three-dimensional, axial-lateral coupled bearing model is used to couple the rotor vibrations with the gear box motion. The vibrations between the individual rotor systems are coupled through the nonlinear gear mesh interactions. The global equations of motion are solved in modal coordinates and the transient vibration of the system is evaluated by a variable time-stepping integration scheme. The relationship between housing vibration and resulting noise of the gear transmission system is generated by linear transfer functions using experimental data. A nonlinear relationship of the noise components to the fundamental mesh frequency is developed using the hypercoherence function. The numerically simulated vibrations and predicted noise of the gear transmission system are compared with the experimental results from the gear noise test rig at NASA Lewis Research Center. Results of the comparison indicate that the global dynamic model developed can accurately simulate the dynamics of a gear transmission system.

  6. Global dynamic modeling of a transmission system

    NASA Technical Reports Server (NTRS)

    Choy, F. K.; Qian, W.

    1993-01-01

    The work performed on global dynamic simulation and noise correlation of gear transmission systems at the University of Akron is outlined. The objective is to develop a comprehensive procedure to simulate the dynamics of the gear transmission system coupled with the effects of gear box vibrations. The developed numerical model is benchmarked with results from experimental tests at NASA Lewis Research Center. The modal synthesis approach is used to develop the global transient vibration analysis procedure used in the model. Modal dynamic characteristics of the rotor-gear-bearing system are calculated by the matrix transfer method while those of the gear box are evaluated by the finite element method (NASTRAN). A three-dimensional, axial-lateral coupled bearing model is used to couple the rotor vibrations with the gear box motion. The vibrations between the individual rotor systems are coupled through the nonlinear gear mesh interactions. The global equations of motion are solved in modal coordinates and the transient vibration of the system is evaluated by a variable time-stepping integration scheme. The relationship between housing vibration and resulting noise of the gear transmission system is generated by linear transfer functions using experimental data. A nonlinear relationship of the noise components to the fundamental mesh frequency is developed using the hypercoherence function. The numerically simulated vibrations and predicted noise of the gear transmission system are compared with the experimental results from the gear noise test rig at NASA Lewis Research Center. Results of the comparison indicate that the global dynamic model developed can accurately simulate the dynamics of a gear transmission system.

  7. Canine echinococcosis in Kyrgyzstan: using prevalence data adjusted for measurement error to develop transmission dynamics models

    PubMed Central

    Ziadinov, I.; Mathis, A.; Trachsel, D.; Rysmukhambetova, A.; Abdyjaparov, T. A.; Kuttubaev, O. T.; Deplazes, P.; Torgerson, P. R.

    2008-01-01

    Echinococcosis is a major emerging zoonosis in central Asia. A cross-sectional study of dogs in four villages in rural Kyrgyzstan was undertaken to investigate the epidemiology and transmission of Echinococcus spp. A total of 466 dogs were examined by arecoline purgation for the presence of Echinococcus granulosus and Echinococcus multilocularis. In addition, a faecal sample from each dog was examined for taeniid eggs. Any taeniid eggs found were investigated using PCR techniques (multiplex and single target PCR) to improve the diagnostic sensitivity by confirming the presence of Echinococcus spp. and to identify E. granulosus strains. A total of 83 (18%) dogs had either E. granulosus adults in purge material and/or E. granulosus eggs in their faeces as confirmed by PCR. Three genotypes of E. granulosus: G1, G4 and the G6/7 complex were shown to be present in these dogs through subsequent sequence analysis. Purge analysis combined with PCR identified 50 dogs that were infected with adult E. multilocularis and/or had E. multilocularis eggs in their faeces (11%). Bayesian techniques were employed to estimate the true prevalence, the diagnostic sensitivity and specificity of the procedures used and the transmission parameters. The sensitivity of arecoline purgation for the detection of echinococcosis in dogs was rather low, with a value of 38% (Credible intervals (CIs) 27–50%) for E. granulosus and 21% (CIs 11–34%) for E. multilocularis. The specificity of arecoline purgation was assumed to be 100%. The sensitivity of coproscopy followed by PCR of the isolated eggs was calculated as 78% (CIs 57–87%) for E. granulosus and 50% (CIs 29–72%) for E. multilocularis with specificity of 93% (CIs 88–96%) and 100% (CIs 97–100), respectively. The 93% specificity of the coprological-PCR for E. granulosus could suggest coprophagia rather than true infections. After adjusting for the sensitivity of the diagnostic procedures, the estimated true prevalence of infection of

  8. EPIFIL: the development of an age-structured model for describing the transmission dynamics and control of lymphatic filariasis.

    PubMed Central

    Norman, R. A.; Chan, M. S.; Srividya, A.; Pani, S. P.; Ramaiah, K. D.; Vanamail, P.; Michael, E.; Das, P. K.; Bundy, D. A.

    2000-01-01

    Mathematical models of transmission dynamics of infectious diseases provide a useful tool for investigating the impact of community based control measures. Previously, we used a dynamic (constant force-of-infection) model for lymphatic filariasis to describe observed patterns of infection and disease in endemic communities. In this paper, we expand the model to examine the effects of control options against filariasis by incorporating the impact of age structure of the human community and by addressing explicitly the dynamics of parasite transmission from and to the vector population. This model is tested using data for Wuchereria bancrofti transmitted by Culex quinquefasciatus in Pondicherry, South India. The results show that chemotherapy has a larger short-term impact than vector control but that the effects of vector control can last beyond the treatment period. In addition we compare rates of recrudescence for drugs with different macrofilaricidal effects. PMID:10982078

  9. Transmission seal development

    NASA Technical Reports Server (NTRS)

    Brien, M.

    1977-01-01

    An experimental evaluation was performed on a high-speed (72.9 m/s, 14,349 ft/min) transmission seal of the synergistic type. During testing of the seal, oil leakage occurred at positive bearing cavity pressures. Modifications were made in an attempt to eliminate the leakage but none were completely successful. Leakage appears to be the result of questionable positioning of the sealing elements resulting in inadequate shaft contact by the oil side sealing element. This condition may be related to the nonsymmetrical shape of the elastomeric retainer and to dimensional changes caused by swelling of the elastomeric retainer from exposure to the sealed fluid. Indications of a speed dependent leakage characteristic were also observed.

  10. Dynamics of a split torque helicopter transmission

    NASA Technical Reports Server (NTRS)

    Rashidi, Majid; Krantz, Timothy

    1992-01-01

    A high reduction ratio split torque gear train has been proposed as an alternative to a planetary configuration for the final stage of a helicopter transmission. A split torque design allows a high ratio of power-to-weight for the transmission. The design studied in this work includes a pivoting beam that acts to balance thrust loads produced by the helical gear meshes in each of two parallel power paths. When the thrust loads are balanced, the torque is split evenly. A mathematical model was developed to study the dynamics of the system. The effects of time varying gear mesh stiffness, static transmission errors, and flexible bearing supports are included in the model. The model was demonstrated with a test case. Results show that although the gearbox has a symmetric configuration, the simulated dynamic behavior of the first and second compound gears are not the same. Also, results show that shaft location and mesh stiffness tuning are significant design parameters that influence the motions of the system.

  11. Avian Influenza spread and transmission dynamics

    USGS Publications Warehouse

    Bourouiba, Lydia; Gourley, Stephen A.; Liu, Rongsong; Takekawa, John Y.; Wu, Jianhong

    2015-01-01

    The spread of highly pathogenic avian influenza (HPAI) viruses of type A of subtype H5N1 has been a serious threat to global public health. Understanding the roles of various (migratory, wild, poultry) bird species in the transmission of these viruses is critical for designing and implementing effective control and intervention measures. Developing appropriate models and mathematical techniques to understand these roles and to evaluate the effectiveness of mitigation strategies have been a challenge. Recent development of the global health surveillance (especially satellite tracking and GIS techniques) and the mathematical theory of dynamical systems combined have gradually shown the promise of some cutting-edge methodologies and techniques in mathematical biology to meet this challenge.

  12. Trypanosome Transmission Dynamics in Tsetse

    PubMed Central

    Aksoy, Serap; Weiss, Brian L.; Attardo, Geoff M.

    2014-01-01

    Tsetse flies (Diptera:Glossinidae) are vectors of African trypanosomes. Tsetse undergo viviparous reproductive biology, and depend on their obligate endosymbiont (genus Wigglesworthia) for the maintenance of fecundity and immune system development. Trypanosomes establish infections in the midgut and salivary glands of the fly. Tsetse’s resistance to trypanosome infection increases as a function of age. Among the factors that mediate resistance to parasites are antimicrobial peptides (AMPs) produced by the Immune deficiency (Imd) signaling pathway, peptidoglycan recognition protein (PGRP) LB, tsetse-EP protein and the integrity of the midgut peritrophic matrix (PM) barrier. The presence of obligate Wigglesworthia during larval development is essential for adult immune system maturation and PM development. Thus, Wigglesworthia prominently influences the vector competency of it’s tsetse host. PMID:25580379

  13. Dynamics of Mechanical Signal Transmission through Prestressed Stress Fibers

    PubMed Central

    Hwang, Yongyun; Barakat, Abdul I.

    2012-01-01

    Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance mechanotransduction in cells; however, a quantitative understanding of the dynamics of this transmission and the physical factors governing it remains lacking. Two key features of the actin cytoskeleton are its viscoelastic nature and the presence of prestress due to actomyosin motor activity. We develop a model of mechanical signal transmission through prestressed viscoelastic actin stress fibers that directly connect the cell surface to the nucleus. The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. To elucidate the physical parameters that govern mechanical signal transmission, we initially focus on the highly simplified case of a single stress fiber. The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. Conversely, signal transmission for axial motion is mediated uniquely by elasticity due to the absence of a prestress restoring force. Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. Only transverse motion yields the rapid and long-distance mechanical signal transmission dynamics observed experimentally. For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission and allows

  14. Dynamics of infectious disease transmission by inhalable respiratory droplets

    PubMed Central

    Stilianakis, Nikolaos I.; Drossinos, Yannis

    2010-01-01

    Transmission of respiratory infectious diseases in humans, for instance influenza, occurs by several modes. Respiratory droplets provide a vector of transmission of an infectious pathogen that may contribute to different transmission modes. An epidemiological model incorporating the dynamics of inhalable respiratory droplets is developed to assess their relevance in the infectious process. Inhalable respiratory droplets are divided into respirable droplets, with droplet diameter less than 10 µm, and inspirable droplets, with diameter in the range 10–100 µm: both droplet classes may be inhaled or settle. Droplet dynamics is determined by their physical properties (size), whereas population dynamics is determined by, among other parameters, the pathogen infectivity and the host contact rates. Three model influenza epidemic scenarios, mediated by different airborne or settled droplet classes, are analysed. The scenarios are distinguished by the characteristic times associated with breathing at contact and with hand-to-face contact. The scenarios suggest that airborne transmission, mediated by respirable droplets, provides the dominant transmission mode in middle and long-term epidemics, whereas inspirable droplets, be they airborne or settled, characterize short-term epidemics with high attack rates. The model neglects close-contact transmission by droplet sprays (direct projection onto facial mucous membranes), retaining close-contact transmission by inspirable droplets. PMID:20164087

  15. On dynamic loads in parallel shaft transmissions. 2: Parameter study

    NASA Technical Reports Server (NTRS)

    Lin, Edward Hsiang-Hsi; Huston, Ronald L.; Coy, John J.

    1987-01-01

    Solutions to the governing equations of a spur gear transmission model, developed in NASA TM-100180 (AVSCOM TM-87-C-2), are presented. Factors affecting the dynamic load are identified. It is found that the dynamic load increases with operating speed up to a system natural frequency. At operating speeds beyond the natural frequency the dynamic load decreases dramatically. Also. it is found that the applied load and shaft inertia have little effect on the dynamic load. Damping and friction decrease the dynamic load. Finally, tooth stiffness has a significant effect on dynamic loading; the higher the stiffness, the lower the dynamic loading. Also, the higher the stiffness the higher the rotating speed required for dynamic response.

  16. Mathematical Models for HIV Transmission Dynamics

    PubMed Central

    Cassels, Susan; Clark, Samuel J.; Morris, Martina

    2012-01-01

    Summary HIV researchers have long appreciated the need to understand the social and behavioral determinants of HIV-related risk behavior, but the cumulative impact of individual behaviors on population-level HIV outcomes can be subtle and counterintuitive, and the methods for studying this are rarely part of a traditional social science or epidemiology training program. Mathematical models provide a way to examine the potential effects of the proximate biologic and behavioral determinants of HIV transmission dynamics, alone and in combination. The purpose of this article is to show how mathematical modeling studies have contributed to our understanding of the dynamics and disparities in the global spread of HIV. Our aims are to demonstrate the value that these analytic tools have for social and behavioral sciences in HIV prevention research, to identify gaps in the current literature, and to suggest directions for future research. PMID:18301132

  17. Transport composite fuselage technology: Impact dynamics and acoustic transmission

    NASA Technical Reports Server (NTRS)

    Jackson, A. C.; Balena, F. J.; Labarge, W. L.; Pei, G.; Pitman, W. A.; Wittlin, G.

    1986-01-01

    A program was performed to develop and demonstrate the impact dynamics and acoustic transmission technology for a composite fuselage which meets the design requirements of a 1990 large transport aircraft without substantial weight and cost penalties. The program developed the analytical methodology for the prediction of acoustic transmission behavior of advanced composite stiffened shell structures. The methodology predicted that the interior noise level in a composite fuselage due to turbulent boundary layer will be less than in a comparable aluminum fuselage. The verification of these analyses will be performed by NASA Langley Research Center using a composite fuselage shell fabricated by filament winding. The program also developed analytical methodology for the prediction of the impact dynamics behavior of lower fuselage structure constructed with composite materials. Development tests were performed to demonstrate that the composite structure designed to the same operating load requirement can have at least the same energy absorption capability as aluminum structure.

  18. X-ray transmission movies of spontaneous dynamic events

    NASA Astrophysics Data System (ADS)

    Smilowitz, L.; Henson, B. F.; Holmes, M.; Novak, A.; Oschwald, D.; Dolgonos, P.; Qualls, B.

    2014-11-01

    We describe a new x-ray radiographic imaging system which allows for continuous x-ray transmission imaging of spontaneous dynamic events. We demonstrate this method on thermal explosions in three plastic bonded formulations of the energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. We describe the x-ray imaging system and triggering developed to enable the continuous imaging of a thermal explosion.

  19. X-ray transmission movies of spontaneous dynamic events.

    PubMed

    Smilowitz, L; Henson, B F; Holmes, M; Novak, A; Oschwald, D; Dolgonos, P; Qualls, B

    2014-11-01

    We describe a new x-ray radiographic imaging system which allows for continuous x-ray transmission imaging of spontaneous dynamic events. We demonstrate this method on thermal explosions in three plastic bonded formulations of the energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. We describe the x-ray imaging system and triggering developed to enable the continuous imaging of a thermal explosion. PMID:25430121

  20. X-ray transmission movies of spontaneous dynamic events

    SciTech Connect

    Smilowitz, L.; Henson, B. F.; Holmes, M.; Novak, A.; Oschwald, D.; Dolgonos, P.; Qualls, B.

    2014-11-15

    We describe a new x-ray radiographic imaging system which allows for continuous x-ray transmission imaging of spontaneous dynamic events. We demonstrate this method on thermal explosions in three plastic bonded formulations of the energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. We describe the x-ray imaging system and triggering developed to enable the continuous imaging of a thermal explosion.

  1. Dynamic Power Flow Controller: Compact Dynamic Phase Angle Regulators for Transmission Power Routing

    SciTech Connect

    2012-01-03

    GENI Project: Varentec is developing compact, low-cost transmission power controllers with fractional power rating for controlling power flow on transmission networks. The technology will enhance grid operations through improved use of current assets and by dramatically reducing the number of transmission lines that have to be built to meet increasing contributions of renewable energy sources like wind and solar. The proposed transmission controllers would allow for the dynamic control of voltage and power flow, improving the grid’s ability to dispatch power in real time to the places where it is most needed. The controllers would work as fail-safe devices whereby the grid would be restored to its present operating state in the event of a controller malfunction instead of failing outright. The ability to affordably and dynamically control power flow with adequate fail-safe switchgear could open up new competitive energy markets which are not possible under the current regulatory structure and technology base.

  2. Nonlinear system guidance in the presence of transmission zero dynamics

    NASA Technical Reports Server (NTRS)

    Meyer, G.; Hunt, L. R.; Su, R.

    1995-01-01

    An iterative procedure is proposed for computing the commanded state trajectories and controls that guide a possibly multiaxis, time-varying, nonlinear system with transmission zero dynamics through a given arbitrary sequence of control points. The procedure is initialized by the system inverse with the transmission zero effects nulled out. Then the 'steady state' solution of the perturbation model with the transmission zero dynamics intact is computed and used to correct the initial zero-free solution. Both time domain and frequency domain methods are presented for computing the steady state solutions of the possibly nonminimum phase transmission zero dynamics. The procedure is illustrated by means of linear and nonlinear examples.

  3. Dynamics of Multistage Gear Transmission with Effects of Gearbox Vibrations

    NASA Technical Reports Server (NTRS)

    Choy, F. K.; Tu, Y. K.; Zakrajsek, J. J.; Townsend, Dennis P.

    1990-01-01

    A comprehensive approach is presented in analyzing the dynamic behavior of multistage gear transmission systems with the effects of gearbox induced vibrations and mass imbalances of the rotor. The modal method, with undamped frequencies and planar mode shapes, is used to reduce the degrees of freedom of the gear system for time-transient dynamic analysis. Both the lateral and torsional vibration modes of each rotor-bearing-gear stage as well as the interstage vibrational characteristics are coupled together through localized gear mesh tooth interactions. In addition, gearbox vibrations are also coupled to the rotor-bearing-gear system dynamics through bearing support forces between the rotor and the gearbox. Transient and steady state dynamics of lateral and torsional vibrations of the geared system are examined in both time and frequency domains to develop interpretations of the overall modal dynamic characteristics under various operating conditions. A typical three-stage geared system is used as an example. Effects of mass imbalance and gearbox vibrations on the system dynamic behavior are presented in terms of modal excitation functions for both lateral and torsional vibrations. Operational characteristics and conclusions are drawn from the results presented.

  4. Contrasting the epidemiological and evolutionary dynamics of influenza spatial transmission

    PubMed Central

    Viboud, Cécile; Nelson, Martha I.; Tan, Yi; Holmes, Edward C.

    2013-01-01

    In the past decade, rapid increases in the availability of high-resolution molecular and epidemiological data, combined with developments in statistical and computational methods to simulate and infer migration patterns, have provided key insights into the spatial dynamics of influenza A viruses in humans. In this review, we contrast findings from epidemiological and molecular studies of influenza virus transmission at different spatial scales. We show that findings are broadly consistent in large-scale studies of inter-regional or inter-hemispheric spread in temperate regions, revealing intense epidemics associated with multiple viral introductions, followed by deep troughs driven by seasonal bottlenecks. However, aspects of the global transmission dynamics of influenza viruses are still debated, especially with respect to the existence of tropical source populations experiencing high levels of genetic diversity and the extent of prolonged viral persistence between epidemics. At the scale of a country or community, epidemiological studies have revealed spatially structured diffusion patterns in seasonal and pandemic outbreaks, which were not identified in molecular studies. We discuss the role of sampling issues in generating these conflicting results, and suggest strategies for future research that may help to fully integrate the epidemiological and evolutionary dynamics of influenza virus over space and time. PMID:23382422

  5. Time Resolved Phase Transitions via Dynamic Transmission Electron Microscopy

    SciTech Connect

    Reed, B W; Armstrong, M R; Blobaum, K J; Browning, N D; Burnham, A K; Campbell, G H; Gee, R; Kim, J S; King, W E; Maiti, A; Piggott, W T; Torralva, B R

    2007-02-22

    The Dynamic Transmission Electron Microscope (DTEM) project is developing an in situ electron microscope with nanometer- and nanosecond-scale resolution for the study of rapid laser-driven processes in materials. We report on the results obtained in a year-long LDRD-supported effort to develop DTEM techniques and results for phase transitions in molecular crystals, reactive multilayer foils, and melting and resolidification of bismuth. We report the first in situ TEM observation of the HMX {beta}-{delta} phase transformation in sub-{micro}m crystals, computational results suggesting the importance of voids and free surfaces in the HMX transformation kinetics, and the first electron diffraction patterns of intermediate states in fast multilayer foil reactions. This project developed techniques which are applicable to many materials systems and will continue to be employed within the larger DTEM effort.

  6. Life and dynamic capacity modeling for aircraft transmissions

    NASA Technical Reports Server (NTRS)

    Savage, Michael

    1991-01-01

    A computer program to simulate the dynamic capacity and life of parallel shaft aircraft transmissions is presented. Five basic configurations can be analyzed: single mesh, compound, parallel, reverted, and single plane reductions. In execution, the program prompts the user for the data file prefix name, takes input from a ASCII file, and writes its output to a second ASCII file with the same prefix name. The input data file includes the transmission configuration, the input shaft torque and speed, and descriptions of the transmission geometry and the component gears and bearings. The program output file describes the transmission, its components, their capabilities, locations, and loads. It also lists the dynamic capability, ninety percent reliability, and mean life of each component and the transmission as a system. Here, the program, its input and output files, and the theory behind the operation of the program are described.

  7. Dynamic analysis of multimesh-gear helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Choy, Fred K.; Townsend, Dennis P.; Oswald, Fred B.

    1988-01-01

    A dynamic analysis of multimesh-gear helicopter transmission systems was performed by correlating analytical simulations with experimental investigations. The two computer programs used in this study, GRDYNMLT and PGT, were developed under NASA/Army sponsorship. Parametric studies of the numerical model with variations on mesh damping ratios, operating speeds, tip-relief tooth modifications, and tooth-spacing errors were performed to investigate the accuracy, application, and limitations of the two computer programs. Although similar levels of dynamic loading were predicted by both programs, the computer code GRDYNMLT was found to be superior and broader in scope. Results from analytical work were also compared with experimental data obtained from the U.S. Army's UH-60A Black Hawk 2240-kW (3000-hp) class, twin-engine helicopter transmission tested at the NASA Lewis Research Center. Good correlation in gear stresses was obtained between the analytical model simulated by GRDYNMLT and the experimental measurements. More realistic mesh damping can be predicted through experimental data correlation.

  8. Development of thermoplastic coated multifunctional transmission elements

    NASA Astrophysics Data System (ADS)

    Golaz, B.; Michaud, V.; de Oliveira, R.; Månson, J.-A. E.

    2012-04-01

    We report on key challenges of the development of steel cords reinforced thermoplastic elastomer composites with smart functionalities: adhesion tailoring for a durable mechanical load transfer through steel cords or other transmission elements by the use of surface treatments and primers, and integrated distributed temperature and strain sensing by the use of embedded fiber optic sensors. Traditional surface treatments including silane coupling agent were outperformed in processing time, adhesion and durability by a fast-curing coupling method using a UV-curable primer; and the integrated distributed temperature and strain sensing capability was demonstrated. The practical applications of the resulting multifunctional transmission element are then discussed in light of these results.

  9. Development of a transmission positron microscope

    NASA Astrophysics Data System (ADS)

    Matsuya, M.; Jinno, S.; Ootsuka, T.; Inoue, M.; Kurihara, T.; Doyama, M.; Inoue, M.; Fujinami, M.

    2011-07-01

    A practical transmission positron microscope (TPM) JEM-1011B has been developed to survey differences in the interaction of positron and electron beams with materials, and is installed in the Slow Positron Facility of High Energy Accelerator Research Organization (KEK). The TPM can share positron and electron beams, and can also be used as a transmission electron microscope (TEM). Positron transmission images up to magnification 10,000× (resolution: 50 nm) and positron diffraction patterns up to 044 family were successfully obtained by the TPM comparing them with those of electrons. The differences in material transmittances for both beams have been measured, and can be explained by the calculated results of the Monte Carlo simulation code PENELOPE-2008.

  10. Great Plains Wind Energy Transmission Development Project

    SciTech Connect

    Brad G. Stevens, P.E.; Troy K. Simonsen; Kerryanne M. Leroux

    2012-06-09

    In fiscal year 2005, the Energy & Environmental Research Center (EERC) received funding from the U.S. Department of Energy (DOE) to undertake a broad array of tasks to either directly or indirectly address the barriers that faced much of the Great Plains states and their efforts to produce and transmit wind energy at the time. This program, entitled Great Plains Wind Energy Transmission Development Project, was focused on the central goal of stimulating wind energy development through expansion of new transmission capacity or development of new wind energy capacity through alternative market development. The original task structure was as follows: Task 1 - Regional Renewable Credit Tracking System (later rescoped to Small Wind Turbine Training Center); Task 2 - Multistate Transmission Collaborative; Task 3 - Wind Energy Forecasting System; and Task 4 - Analysis of the Long-Term Role of Hydrogen in the Region. As carried out, Task 1 involved the creation of the Small Wind Turbine Training Center (SWTTC). The SWTTC, located Grand Forks, North Dakota, consists of a single wind turbine, the Endurance S-250, on a 105-foot tilt-up guyed tower. The S-250 is connected to the electrical grid on the 'load side' of the electric meter, and the power produced by the wind turbine is consumed locally on the property. Establishment of the SWTTC will allow EERC personnel to provide educational opportunities to a wide range of participants, including grade school through college-level students and the general public. In addition, the facility will allow the EERC to provide technical training workshops related to the installation, operation, and maintenance of small wind turbines. In addition, under Task 1, the EERC hosted two small wind turbine workshops on May 18, 2010, and March 8, 2011, at the EERC in Grand Forks, North Dakota. Task 2 involved the EERC cosponsoring and aiding in the planning of three transmission workshops in the midwest and western regions. Under Task 3, the

  11. Dynamic responses and vibration control of the transmission tower-line system: a state-of-the-art review.

    PubMed

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping

    2014-01-01

    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

  12. Dynamic Responses and Vibration Control of the Transmission Tower-Line System: A State-of-the-Art Review

    PubMed Central

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping

    2014-01-01

    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

  13. Varicella susceptibility and transmission dynamics in Slovenia

    PubMed Central

    2010-01-01

    Background A cross-sectional, age-stratified study was conducted to determine varicella-zoster seroprevalence and force of infection in Slovenia. Methods 3689 serum samples were tested for VZV IgG antibodies with an enzyme immunoassay. Semiparametric and parametric modelling were used to estimate the force of infection. Results Overall, 85.6% of serum samples were seropositive. Age-specific prevalence rose rapidly in preschool children and over 90% of 8 years old tested positive for VZV. However, 2.8% of serum samples among women of childbearing age were seronegative. Semiparametric modelling yielded force of infection estimates of 0.182 (95% CI 0.158-0.206), 0.367 (95% CI 0.285-0.448) and 0.008 (95% CI 0.0-0.032) for age groups 0.5- < 6, 6-11 and ≥12 years, respectively, and 0.175 (95% CI 0.147-0.202), 0.391 (95% CI 0.303-0.480) and 0.025 (95% CI 0.003-0.046) for age groups 0.5- < 5, 5-9 and ≥10 years, respectively. Conclusions Regardless of the age grouping used, the highest transmission occurred in children in their first years of school. PMID:20573202

  14. Pulsed Power for a Dynamic Transmission Electron Microscope

    SciTech Connect

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  15. MRI dynamic range and its compatibility with signal transmission media

    NASA Astrophysics Data System (ADS)

    Gabr, Refaat E.; Schär, Michael; Edelstein, Arthur D.; Kraitchman, Dara L.; Bottomley, Paul A.; Edelstein, William A.

    2009-06-01

    As the number of MRI phased array coil elements grows, interactions among cables connecting them to the system receiver become increasingly problematic. Fiber optic or wireless links would reduce electromagnetic interference, but their dynamic range (DR) is generally less than that of coaxial cables. Raw MRI signals, however, have a large DR because of the high signal amplitude near the center of k-space. Here, we study DR in MRI in order to determine the compatibility of MRI multicoil imaging with non-coaxial cable signal transmission. Since raw signal data are routinely discarded, we have developed an improved method for estimating the DR of MRI signals from conventional magnitude images. Our results indicate that the DR of typical surface coil signals at 3 T for human subjects is less than 88 dB, even for three-dimensional acquisition protocols. Cardiac and spine coil arrays had a maximum DR of less than 75 dB and head coil arrays less than 88 dB. The DR derived from magnitude images is in good agreement with that measured from raw data. The results suggest that current analog fiber optic links, with a spurious-free DR of 60-70 dB at 500 kHz bandwidth, are not by themselves adequate for transmitting MRI data from volume or array coils with DR ˜90 dB. However, combining analog links with signal compression might make non-coaxial cable signal transmission viable.

  16. The Transmission Dynamics of Human Immunodeficiency Virus (HIV)

    NASA Astrophysics Data System (ADS)

    May, R. M.; Anderson, R. M.

    1988-10-01

    The paper first reviews data on HIV infections and AIDS disease among homosexual men, heterosexuals, intravenous (IV) drug abusers and children born to infected mothers, in both developed and developing countries. We survey such information as is currently available about the distribution of incubation times that elapse between HIV infection and the appearance of AIDS, about the fraction of those infected with HIV who eventually go on to develop AIDS, about time-dependent patterns of infectiousness and about distributions of rates of acquiring new sexual or needle-sharing partners. With this information, models for the transmission dynamics of HIV are developed, beginning with deliberately oversimplified models and progressing - on the basis of the understanding thus gained - to more complex ones. Where possible, estimates of the model's parameters are derived from the epidemiological data, and predictions are compared with observed trends. We also combine these epidemiological models with demographic considerations to assess the effects that heterosexually-transmitted HIV/AIDS may eventually have on rates of population growth, on age profiles and on associated economic and social indicators, in African and other countries. The degree to which sexual or other habits must change to bring the `basic reproductive rate', R_0, of HIV infections below unity is discussed. We conclude by outlining some research needs, both in the refinement and development of models and in the collection of epidemiological data.

  17. On dynamic loads in parallel shaft transmissions. 1: Modelling and analysis

    NASA Technical Reports Server (NTRS)

    Lin, Edward Hsiang-Hsi; Huston, Ronald L.; Coy, John J.

    1987-01-01

    A model of a simple parallel-shaft, spur-gear transmission is presented. The model is developed to simulate dynamic loads in power transmissions. Factors affecting these loads are identified. Included are shaft stiffness, local compliance due to contact stress, load sharing, and friction. Governing differential equations are developed and a solution procedure is outlined. A parameter study of the solutions is presented in NASA TM-100181 (AVSCOM TM-87-C-3).

  18. Large rotorcraft transmission technology development program

    NASA Technical Reports Server (NTRS)

    Mack, J. C.

    1983-01-01

    Testing of a U.S. Army XCH-62 HLH aft rotor transmission under NASA Contract NAS 3-22143 was successfully completed. This test establishes the feasibility of large, high power rotorcraft transmissions as well as demonstrating the resolution of deficiencies identified during the HLH advanced technology programs and reported by USAAMRDLTR-77-38. Over 100 hours of testing was conducted. At the 100% design power rating of 10,620 horsepower, the power transferred through a single spiral bevel gear mesh is more than twice that of current helicopter bevel gearing. In the original design of these gears, industry-wide design methods were employed and failures were experienced which identified problem areas unique to gear size. To remedy this technology shortfall, a program was developed to predict gear stresses using finite element analysis for complete and accurate representation of the gear tooth and supporting structure. To validate the finite element methodology gear strain data from the existing U.S. Army HLH aft transmission was acquired, and existing data from smaller gears were made available.

  19. Uncovering the transmission dynamics of Plasmodium vivax using population genetics

    PubMed Central

    Barry, Alyssa E.; Waltmann, Andreea; Koepfli, Cristian; Barnadas, Celine; Mueller, Ivo

    2015-01-01

    Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes. PMID:25891915

  20. Epidemiology and Transmission Dynamics of West Nile Virus Disease

    PubMed Central

    Komar, Nicholas; Nasci, Roger S.; Montgomery, Susan P.; O'Leary, Daniel R.; Campbell, Grant L.

    2005-01-01

    From 1937 until 1999, West Nile virus (WNV) garnered scant medical attention as the cause of febrile illness and sporadic encephalitis in parts of Africa, Asia, and Europe. After the surprising detection of WNV in New York City in 1999, the virus has spread dramatically westward across the United States, southward into Central America and the Caribbean, and northward into Canada, resulting in the largest epidemics of neuroinvasive WNV disease ever reported. From 1999 to 2004, >7,000 neuroinvasive WNV disease cases were reported in the United States. In 2002, WNV transmission through blood transfusion and organ transplantation was described for the first time, intrauterine transmission was first documented, and possible transmission through breastfeeding was reported. This review highlights new information regarding the epidemiology and dynamics of WNV transmission, providing a new platform for further research into preventing and controlling WNV disease. PMID:16102302

  1. Design studies for the transmission simulator method of experimental dynamic substructuring.

    SciTech Connect

    Mayes, Randall Lee; Arviso, Michael

    2010-05-01

    In recent years, a successful method for generating experimental dynamic substructures has been developed using an instrumented fixture, the transmission simulator. The transmission simulator method solves many of the problems associated with experimental substructuring. These solutions effectively address: (1) rotation and moment estimation at connection points; (2) providing substructure Ritz vectors that adequately span the connection motion space; and (3) adequately addressing multiple and continuous attachment locations. However, the transmission simulator method may fail if the transmission simulator is poorly designed. Four areas of the design addressed here are: (1) designating response sensor locations; (2) designating force input locations; (3) physical design of the transmission simulator; and (4) modal test design. In addition to the transmission simulator design investigations, a review of the theory with an example problem is presented.

  2. Transmission Dynamics of Rhodesian Sleeping Sickness at the Interface of Wildlife and Livestock Areas.

    PubMed

    Auty, Harriet; Morrison, Liam J; Torr, Stephen J; Lord, Jennifer

    2016-08-01

    Many wilderness areas of East and Southern Africa are foci for Rhodesian sleeping sickness, a fatal zoonotic disease caused by trypanosomes transmitted by tsetse flies. Although transmission in these foci is traditionally driven by wildlife reservoirs, rising human and livestock populations may increase the role of livestock in transmission cycles. Deciphering transmission dynamics at wildlife and livestock interface areas is key to developing appropriate control. Data are lacking for key parameters, including host distributions, tsetse density, and mortality rates, and the relative roles of livestock and wildlife as hosts in fragmented habitats, limiting the development of meaningful models to assist in the assessment and implementation of control strategies. PMID:27262917

  3. Wireless Power Transmission Technology Development and Demonstrations

    NASA Astrophysics Data System (ADS)

    Steinsiek, F.; Weber, K.-H.; Foth, W.-P.; Foth, H. J.; Schäfer, C.

    2004-12-01

    The Wireless Power Transmission (WPT) technology has been treated to a wide extent in the recent years. A broad variety of applications has been investigated, from earth to orbit, orbit to earth, in-orbit and planetary ones, as for moon and Mars missions. In this course the question to use laser or microwave technology has widely been discussed. Beaming energy to spacecrafts could provide an important space mission-economic potential. It promises significant reduction in the cost of access to space, for scientific and commercial missions, and increases the mission capabilities for in-space systems. For the future enhancement of ISS capabilities and operational efficiency, the use of WPT technology became part of the technology research planning for the ISS. The WPT may have the potential of providing operational benefits, increase of spacecraft systems efficiency for elements like co-orbiting platforms, transfer vehicles or other ISS related in-orbit spacecrafts, and planetary exploration vehicles. The laser technology provides specific technical, operational and economic benefits compared to microwave applications and provides the actual basis for the envisioned wireless power transmission concepts. An outlook in terms of future wireless power perspectives, both for terrestrial as for space-to-space scenarios is given; these applications are part of a technology demonstration roadmap for wireless power transmission key- and supporting technologies, which is characterized by dedicated technology demonstration milestones on ground and in space. The actual technology development philosophy as conceived at EADS-Space Transportation is described and includes main system demonstration missions, as a laboratory test bed employing a small rover system, a scaled airship model demonstration as planned in 2004 and an experiment onboard the International Space Station ISS. These demonstrations represent milestones in terms of technical capability verification on the way to

  4. Mode of Parainfluenza Virus Transmission Determines the Dynamics of Primary Infection and Protection from Reinfection

    PubMed Central

    Burke, Crystal W.; Bridges, Olga; Brown, Sherri; Rahija, Richard; Russell, Charles J.

    2013-01-01

    Little is known about how the mode of respiratory virus transmission determines the dynamics of primary infection and protection from reinfection. Using non-invasive imaging of murine parainfluenza virus 1 (Sendai virus) in living mice, we determined the frequency, timing, dynamics, and virulence of primary infection after contact and airborne transmission, as well as the tropism and magnitude of reinfection after subsequent challenge. Contact transmission of Sendai virus was 100% efficient, phenotypically uniform, initiated and grew to robust levels in the upper respiratory tract (URT), later spread to the lungs, grew to a lower level in the lungs than the URT, and protected from reinfection completely in the URT yet only partially in the lungs. Airborne transmission through 7.6-cm and 15.2-cm separations between donor and recipient mice was 86%–100% efficient. The dynamics of primary infection after airborne transmission varied between individual mice and included the following categories: (a) non-productive transmission, (b) tracheal dominant, (c) tracheal initiated yet respiratory disseminated, and (d) nasopharyngeal initiated yet respiratory disseminated. Any previous exposure to Sendai virus infection protected from mortality and severe morbidity after lethal challenge. Furthermore, a higher level of primary infection in a given respiratory tissue (nasopharynx, trachea, or lungs) was inversely correlated with the level of reinfection in that same tissue. Overall, the mode of transmission determined the dynamics and tropism of primary infection, which in turn governed the level of seroconversion and protection from reinfection. These data are the first description of the dynamics of respiratory virus infection and protection from reinfection throughout the respiratory tracts of living animals after airborne transmission. This work provides a basis for understanding parainfluenza virus transmission and protective immunity and for developing novel vaccines and

  5. Effect of variability in weather conditions on conductor temperature and the dynamic rating of transmission lines

    SciTech Connect

    Foss, S.D.; Lin, S.H. ); Maraio, R.A.; Schrayshuen, H. )

    1988-10-01

    Simultaneous weather and conductor data were collected from these locations situated in New York State and Western Massachusetts. The two New York State locations represent the termination points of a 230 kV seventy-mile overhead line. The transmission line consists of a Drake 795 kcmil ACSR conductor. Data were monitored using on-line sensor equipment developed by the Research and Development Department of the Niagara Mohawk Power Corporation. The purposes of the investigation were to analyze variability in weather conditions, conductor temperature and calculated dynamic ratings that exist along transmission lines. Reported here are variabilities in air temperature, wind speed, conductor current, conductor surface temperature and calculated dynamic ratings.

  6. Dynamics and transmissivity of optomechanical system in squeezed environment

    NASA Astrophysics Data System (ADS)

    Farooq, K.; Khan, M. A.; Wang, L. C.; Yi, X. X.

    2015-10-01

    Cavity quantum optomechanics offers the potential to explore quantum nature and characteristics in microscopic and nanoquantum systems. In this area, various experimental setup trends to explore, while theoretical approaches seek to lead the concrete bases for these amazing characteristics. In this paper, we present the dynamic features, stabilization and the optical response (transmission) properties of an optomechanical system in the squeezed environment theoretically. Particularly, we calculate optical intensity transmission coefficient of the optomechanical system. The optomechanical system has driven coherently with the external laser field.

  7. Modeling the Dynamic Transmission of Dengue Fever: Investigating Disease Persistence

    PubMed Central

    de Castro Medeiros, Líliam César; Castilho, César Augusto Rodrigues; Braga, Cynthia; de Souza, Wayner Vieira; Regis, Leda; Monteiro, Antonio Miguel Vieira

    2011-01-01

    Background Dengue is a disease of great complexity, due to interactions between humans, mosquitoes and various virus serotypes as well as efficient vector survival strategies. Thus, understanding the factors influencing the persistence of the disease has been a challenge for scientists and policy makers. The aim of this study is to investigate the influence of various factors related to humans and vectors in the maintenance of viral transmission during extended periods. Methodology/Principal Findings We developed a stochastic cellular automata model to simulate the spread of dengue fever in a dense community. Each cell can correspond to a built area, and human and mosquito populations are individually monitored during the simulations. Human mobility and renewal, as well as vector infestation, are taken into consideration. To investigate the factors influencing the maintenance of viral circulation, two sets of simulations were performed: (1st) varying human renewal rates and human population sizes and (2nd) varying the house index (fraction of infested buildings) and vector per human ratio. We found that viral transmission is inhibited with the combination of small human populations with low renewal rates. It is also shown that maintenance of viral circulation for extended periods is possible at low values of house index. Based on the results of the model and on a study conducted in the city of Recife, Brazil, which associates vector infestation with Aedes aegytpi egg counts, we question the current methodology used in calculating the house index, based on larval survey. Conclusions/Significance This study contributed to a better understanding of the dynamics of dengue subsistence. Using basic concepts of metapopulations, we concluded that low infestation rates in a few neighborhoods ensure the persistence of dengue in large cities and suggested that better strategies should be implemented to obtain measures of house index values, in order to improve the dengue

  8. Recasting the theory of mosquito-borne pathogen transmission dynamics and control

    PubMed Central

    Smith, David L.; Perkins, T. Alex; Reiner, Robert C.; Barker, Christopher M.; Niu, Tianchan; Chaves, Luis Fernando; Ellis, Alicia M.; George, Dylan B.; Le Menach, Arnaud; Pulliam, Juliet R. C.; Bisanzio, Donal; Buckee, Caroline; Chiyaka, Christinah; Cummings, Derek A. T.; Garcia, Andres J.; Gatton, Michelle L.; Gething, Peter W.; Hartley, David M.; Johnston, Geoffrey; Klein, Eili Y.; Michael, Edwin; Lloyd, Alun L.; Pigott, David M.; Reisen, William K.; Ruktanonchai, Nick; Singh, Brajendra K.; Stoller, Jeremy; Tatem, Andrew J.; Kitron, Uriel; Godfray, H. Charles J.; Cohen, Justin M.; Hay, Simon I.; Scott, Thomas W.

    2014-01-01

    Mosquito-borne diseases pose some of the greatest challenges in public health, especially in tropical and sub-tropical regions of the world. Efforts to control these diseases have been underpinned by a theoretical framework developed for malaria by Ross and Macdonald, including models, metrics for measuring transmission, and theory of control that identifies key vulnerabilities in the transmission cycle. That framework, especially Macdonald's formula for R0 and its entomological derivative, vectorial capacity, are now used to study dynamics and design interventions for many mosquito-borne diseases. A systematic review of 388 models published between 1970 and 2010 found that the vast majority adopted the Ross–Macdonald assumption of homogeneous transmission in a well-mixed population. Studies comparing models and data question these assumptions and point to the capacity to model heterogeneous, focal transmission as the most important but relatively unexplored component in current theory. Fine-scale heterogeneity causes transmission dynamics to be nonlinear, and poses problems for modeling, epidemiology and measurement. Novel mathematical approaches show how heterogeneity arises from the biology and the landscape on which the processes of mosquito biting and pathogen transmission unfold. Emerging theory focuses attention on the ecological and social context for mosquito blood feeding, the movement of both hosts and mosquitoes, and the relevant spatial scales for measuring transmission and for modeling dynamics and control. PMID:24591453

  9. Recasting the theory of mosquito-borne pathogen transmission dynamics and control.

    PubMed

    Smith, David L; Perkins, T Alex; Reiner, Robert C; Barker, Christopher M; Niu, Tianchan; Chaves, Luis Fernando; Ellis, Alicia M; George, Dylan B; Le Menach, Arnaud; Pulliam, Juliet R C; Bisanzio, Donal; Buckee, Caroline; Chiyaka, Christinah; Cummings, Derek A T; Garcia, Andres J; Gatton, Michelle L; Gething, Peter W; Hartley, David M; Johnston, Geoffrey; Klein, Eili Y; Michael, Edwin; Lloyd, Alun L; Pigott, David M; Reisen, William K; Ruktanonchai, Nick; Singh, Brajendra K; Stoller, Jeremy; Tatem, Andrew J; Kitron, Uriel; Godfray, H Charles J; Cohen, Justin M; Hay, Simon I; Scott, Thomas W

    2014-04-01

    Mosquito-borne diseases pose some of the greatest challenges in public health, especially in tropical and sub-tropical regions of the world. Efforts to control these diseases have been underpinned by a theoretical framework developed for malaria by Ross and Macdonald, including models, metrics for measuring transmission, and theory of control that identifies key vulnerabilities in the transmission cycle. That framework, especially Macdonald's formula for R0 and its entomological derivative, vectorial capacity, are now used to study dynamics and design interventions for many mosquito-borne diseases. A systematic review of 388 models published between 1970 and 2010 found that the vast majority adopted the Ross-Macdonald assumption of homogeneous transmission in a well-mixed population. Studies comparing models and data question these assumptions and point to the capacity to model heterogeneous, focal transmission as the most important but relatively unexplored component in current theory. Fine-scale heterogeneity causes transmission dynamics to be nonlinear, and poses problems for modeling, epidemiology and measurement. Novel mathematical approaches show how heterogeneity arises from the biology and the landscape on which the processes of mosquito biting and pathogen transmission unfold. Emerging theory focuses attention on the ecological and social context for mosquito blood feeding, the movement of both hosts and mosquitoes, and the relevant spatial scales for measuring transmission and for modeling dynamics and control. PMID:24591453

  10. Recent developments in alcoholism:genetic transmission.

    PubMed

    Goldman, D

    1993-01-01

    This chapter is an overview of developments in the study of genetic factors in vulnerability in alcoholism. The focus is on recent developments, including heritability studies in twins and transmission studies in families, both of which have continued to reveal evidence for a substantial role for genetic factors but also for etiologic complexity and variation in vulnerability across generations and across cultures. Studies are discussed which utilized psychophysiological and neurochemical markers for alcoholism for analysis of genetic association, transmission, and linkage. These markers include the low P300 event-related potential, sensitivity to ethanol's intoxicating and euphoric effects, platelet adenylate cyclase, and neurotransmitter metabolite concentrations. Although it is highly likely that many alcoholism-associated physiologic phenotypes are secondary traits, these approaches have increased the specificity of genetic analyses and genetic analyses are clarifying their relationship to alcoholism. For example, early efforts to study, in families, the co-occurrence of the P300 marker and alcoholism have yielded results indicating that the P300 abnormality precedes significant exposure to alcohol and that relatives of alcoholics are more likely to have this trait. In the area of animal models, two nonhuman primate species, the vervet monkey and the rhesus macaque, were shown to willingly consume alcohol to intoxicating blood levels. Also, linkage studies using the quantitative trait locus (QTL) mapping strategy were attempted for phenotypes relevant for alcoholism. The QTL strategy is theoretically capable of identifying determinant genes which contribute only a small portion of the variance. In human linkage studies, a genetic association was found to the DRD2 dopamine receptor. The DRD2 finding generated controversy, as a number of other groups failed to replicate it, and also focused attention on the advantages and pitfalls of the population association

  11. A review of malaria transmission dynamics in forest ecosystems

    PubMed Central

    2014-01-01

    Malaria continues to be a major health problem in more than 100 endemic countries located primarily in tropical and sub-tropical regions around the world. Malaria transmission is a dynamic process and involves many interlinked factors, from uncontrollable natural environmental conditions to man-made disturbances to nature. Almost half of the population at risk of malaria lives in forest areas. Forests are hot beds of malaria transmission as they provide conditions such as vegetation cover, temperature, rainfall and humidity conditions that are conducive to distribution and survival of malaria vectors. Forests often lack infrastructure and harbor tribes with distinct genetic traits, socio-cultural beliefs and practices that greatly influence malaria transmission dynamics. Here we summarize the various topographical, entomological, parasitological, human ecological and socio-economic factors, which are crucial and shape malaria transmission in forested areas. An in-depth understanding and synthesis of the intricate relationship of these parameters in achieving better malaria control in various types of forest ecosystems is emphasized. PMID:24912923

  12. X-ray transmission microscope development

    NASA Technical Reports Server (NTRS)

    Kaukler, William F.; Rosenberger, Franz E.

    1995-01-01

    We are developing a hard x-ray microscope for direct observation of solidification dynamics in metal alloys and metal matrix composites. The Fein-Focus Inc. x-ray source was delivered in September and found to perform better than expected. Confirmed resolution of better than 2 micrometers was obtained and magnifications up to 800X were measured. Nickel beads of 30 micrometer diameter were easily detected through 6mm of aluminum. X-ray metallography was performed on several specimens showing high resolution and clear definition of 3-dimensional structures. Prototype furnace installed and tested.

  13. Characterising the Transmission Dynamics of Acinetobacter baumannii in Intensive Care Units Using Hidden Markov Models.

    PubMed

    Doan, Tan N; Kong, David C M; Marshall, Caroline; Kirkpatrick, Carl M J; McBryde, Emma S

    2015-01-01

    Little is known about the transmission dynamics of Acinetobacter baumannii in hospitals, despite such information being critical for designing effective infection control measures. In the absence of comprehensive epidemiological data, mathematical modelling is an attractive approach to understanding transmission process. The statistical challenge in estimating transmission parameters from infection data arises from the fact that most patients are colonised asymptomatically and therefore the transmission process is not fully observed. Hidden Markov models (HMMs) can overcome this problem. We developed a continuous-time structured HMM to characterise the transmission dynamics, and to quantify the relative importance of different acquisition sources of A. baumannii in intensive care units (ICUs) in three hospitals in Melbourne, Australia. The hidden states were the total number of patients colonised with A. baumannii (both detected and undetected). The model input was monthly incidence data of the number of detected colonised patients (observations). A Bayesian framework with Markov chain Monte Carlo algorithm was used for parameter estimations. We estimated that 96-98% of acquisition in Hospital 1 and 3 was due to cross-transmission between patients; whereas most colonisation in Hospital 2 was due to other sources (sporadic acquisition). On average, it takes 20 and 31 days for each susceptible individual in Hospital 1 and Hospital 3 to become colonised as a result of cross-transmission, respectively; whereas it takes 17 days to observe one new colonisation from sporadic acquisition in Hospital 2. The basic reproduction ratio (R0) for Hospital 1, 2 and 3 was 1.5, 0.02 and 1.6, respectively. Our study is the first to characterise the transmission dynamics of A. baumannii using mathematical modelling. We showed that HMMs can be applied to sparse hospital infection data to estimate transmission parameters despite unobserved events and imperfect detection of the organism

  14. Dynamics of Pertussis Transmission in the United States.

    PubMed

    Magpantay, F M G; Rohani, P

    2015-06-15

    Past patterns of infectious disease transmission set the stage on which modern epidemiologic dynamics are played out. Here, we present a comprehensive account of pertussis (whooping cough) transmission in the United States during the early vaccine era. We analyzed recently digitized weekly incidence records from Morbidity and Mortality Weekly Reports from 1938 to 1955, when the whole-cell pertussis vaccine was rolled out, and related them to contemporary patterns of transmission and resurgence documented in monthly incidence data from the National Notifiable Diseases Surveillance System. We found that, during the early vaccine era, pertussis epidemics in US states could be categorized as 1) annual, 2) initially annual and later multiennial, or 3) multiennial. States with predominantly annual cycles tended to have higher per capita birth rates, more household crowding, more children per family, and lower rates of school attendance than the states with multiennial cycles. Additionally, states that exhibited annual epidemics during 1938-1955 have had the highest recent (2001-2010) incidence, while those states that transitioned from annual cycles to multiennial cycles have had relatively low recent incidence. Our study provides an extensive picture of pertussis epidemiology in the United States dating back to the onset of vaccination, a back-story that could aid epidemiologists in understanding contemporary transmission patterns. PMID:26022662

  15. Transmission Dynamics of Borrelia turicatae from the Arthropod Vector

    PubMed Central

    Boyle, William K.; Wilder, Hannah K.; Lawrence, Amanda M.; Lopez, Job E.

    2014-01-01

    Background With the global distribution, morbidity, and mortality associated with tick and louse-borne relapsing fever spirochetes, it is important to understand the dynamics of vector colonization by the bacteria and transmission to the host. Tick-borne relapsing fever spirochetes are blood-borne pathogens transmitted through the saliva of soft ticks, yet little is known about the transmission capability of these pathogens during the relatively short bloodmeal. This study was therefore initiated to understand the transmission dynamics of the relapsing fever spirochete Borrelia turicatae from the vector Ornithodoros turicata, and the subsequent dissemination of the bacteria upon entry into murine blood. Methodology/Principal Findings To determine the minimum number of ticks required to transmit spirochetes, one to three infected O. turicata were allowed to feed to repletion on individual mice. Murine infection and dissemination of the spirochetes was evaluated by dark field microscopy of blood, quantitative PCR, and immunoblotting against B. turicatae protein lysates and a recombinant antigen, the Borrelia immunogenic protein A. Transmission frequencies were also determined by interrupting the bloodmeal 15 seconds after tick attachment. Scanning electron microscopy (SEM) was performed on infected salivary glands to detect spirochetes within acini lumen and excretory ducts. Furthermore, spirochete colonization and dissemination from the bite site was investigated by feeding infected O. turicata on the ears of mice, removing the attachment site after engorment, and evaluating murine infection. Conclusion/Significance Our findings demonstrated that three ticks provided a sufficient infectious dose to infect nearly all animals, and B. turicatae was transmitted within seconds of tick attachment. Spirochetes were also detected in acini lumen of salivary glands by SEM. Upon host entry, B. turicatae did not require colonization of the bite site to establish murine

  16. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    PubMed Central

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-01-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies. PMID:26038886

  17. Transmission Dynamics of Methicillin-Resistant Staphylococcus aureus in Pigs

    PubMed Central

    Crombé, Florence; Argudín, M. Angeles; Vanderhaeghen, Wannes; Hermans, Katleen; Haesebrouck, Freddy; Butaye, Patrick

    2013-01-01

    From the mid-2000s on, numerous studies have shown that methicillin-resistant Staphylococcus aureus (MRSA), renowned as human pathogen, has a reservoir in pigs and other livestock. In Europe and North America, clonal complex (CC) 398 appears to be the predominant lineage involved. Especially worrisome is its capacity to contaminate humans in close contact with affected animals. Indeed, the typical multi-resistant phenotype of MRSA CC398 and its observed ability of easily acquiring genetic material suggests that MRSA CC398 strains with an increased virulence potential may emerge, for which few therapeutic options would remain. This questions the need to implement interventions to control the presence and spread of MRSA CC398 among pigs. MRSA CC398 shows a high but not fully understood transmission potential in the pig population and is able to persist within that population. Although direct contact is probably the main route for MRSA transmission between pigs, also environmental contamination, the presence of other livestock, the herd size, and farm management are factors that may be involved in the dissemination of MRSA CC398. The current review aims at summarizing the research that has so far been done on the transmission dynamics and risk factors for introduction and persistence of MRSA CC398 in farms. PMID:23518663

  18. On the Identifiability of Transmission Dynamic Models for Infectious Diseases.

    PubMed

    Lintusaari, Jarno; Gutmann, Michael U; Kaski, Samuel; Corander, Jukka

    2016-03-01

    Understanding the transmission dynamics of infectious diseases is important for both biological research and public health applications. It has been widely demonstrated that statistical modeling provides a firm basis for inferring relevant epidemiological quantities from incidence and molecular data. However, the complexity of transmission dynamic models presents two challenges: (1) the likelihood function of the models is generally not computable, and computationally intensive simulation-based inference methods need to be employed, and (2) the model may not be fully identifiable from the available data. While the first difficulty can be tackled by computational and algorithmic advances, the second obstacle is more fundamental. Identifiability issues may lead to inferences that are driven more by prior assumptions than by the data themselves. We consider a popular and relatively simple yet analytically intractable model for the spread of tuberculosis based on classical IS6110 fingerprinting data. We report on the identifiability of the model, also presenting some methodological advances regarding the inference. Using likelihood approximations, we show that the reproductive value cannot be identified from the data available and that the posterior distributions obtained in previous work have likely been substantially dominated by the assumed prior distribution. Further, we show that the inferences are influenced by the assumed infectious population size, which generally has been kept fixed in previous work. We demonstrate that the infectious population size can be inferred if the remaining epidemiological parameters are already known with sufficient precision. PMID:26739450

  19. Dynamic high-speed acquisition system design of transmission error with USB based on LabVIEW and FPGA

    NASA Astrophysics Data System (ADS)

    Zheng, Yong; Chen, Yan

    2013-10-01

    To realize the design of dynamic acquisition system for real-time detection of transmission chain error is very important to improve the machining accuracy of machine tool. In this paper, the USB controller and FPGA is used for hardware platform design, combined with LabVIEW to design user applications, NI-VISA is taken for develop USB drivers, and ultimately achieve the dynamic acquisition system design of transmission error

  20. Development of helicopter transmission seals, task 2

    NASA Technical Reports Server (NTRS)

    Hayden, T. S.; Keller, C. H., Jr.

    1973-01-01

    High speed helicopter transmission seal concepts were designed, fabricated and tested. The concepts were a dual element split ring seal and a circumferential seal. The tests were performed in a rig using an actual input quill assembly. The test conditions were selected to simulate transmission operation and were 230 F oil temperature, and a sliding speed of 9400 ft/min. The split ring seal exhibited gross leakage and was considered unsatisfactory, while the circumferential seal leakage was less than 1 c.c./hour; this leakage is within acceptable limits. The circumferential seal wear was only to .0005 inches during a 100 hour run (40 starts and stops). During a 40 hour contamination test (mesh silica flour) the seal total wear was a maximum of .004 inches. This wear is considered acceptable.

  1. Detection of allosteric signal transmission by information-theoretic analysis of protein dynamics

    PubMed Central

    Pandini, Alessandro; Fornili, Arianna; Fraternali, Franca; Kleinjung, Jens

    2012-01-01

    Allostery offers a highly specific way to modulate protein function. Therefore, understanding this mechanism is of increasing interest for protein science and drug discovery. However, allosteric signal transmission is difficult to detect experimentally and to model because it is often mediated by local structural changes propagating along multiple pathways. To address this, we developed a method to identify communication pathways by an information-theoretical analysis of molecular dynamics simulations. Signal propagation was described as information exchange through a network of correlated local motions, modeled as transitions between canonical states of protein fragments. The method was used to describe allostery in two-component regulatory systems. In particular, the transmission from the allosteric site to the signaling surface of the receiver domain NtrC was shown to be mediated by a layer of hub residues. The location of hubs preferentially connected to the allosteric site was found in close agreement with key residues experimentally identified as involved in the signal transmission. The comparison with the networks of the homologues CheY and FixJ highlighted similarities in their dynamics. In particular, we showed that a preorganized network of fragment connections between the allosteric and functional sites exists already in the inactive state of all three proteins.—Pandini, A., Fornili, A., Fraternali, F., Kleinjung, J. Detection of allosteric signal transmission by information-theoretic analysis of protein dynamics. PMID:22071506

  2. The dynamics, transmission, and population impacts of avian malaria in native hawaiian birds: A modeling approach

    USGS Publications Warehouse

    Samuel, M.D.; Hobbelen, P.H.F.; Decastro, F.; Ahumada, J.A.; Lapointe, D.A.; Atkinson, C.T.; Woodworth, B.L.; Hart, P.J.; Duffy, D.C.

    2011-01-01

    We developed an epidemiological model of avian malaria (Plasmodium relictum) across an altitudinal gradient on the island of Hawaii that includes the dynamics of the host, vector, and parasite. This introduced mosquito-borne disease is hypothesized to have contributed to extinctions and major shifts in the altitudinal distribution of highly susceptible native forest birds. Our goal was to better understand how biotic and abiotic factors influence the intensity of malaria transmission and impact on susceptible populations of native Hawaiian forest birds. Our model illustrates key patterns in the malaria-forest bird system: high malaria transmission in low-elevation forests with minor seasonal or annual variation in infection;episodic transmission in mid-elevation forests with site-to-site, seasonal, and annual variation depending on mosquito dynamics;and disease refugia in high-elevation forests with only slight risk of infection during summer. These infection patterns are driven by temperature and rainfall effects on parasite incubation period and mosquito dynamics across an elevational gradient and the availability of larval habitat, especially in mid-elevation forests. The results from our model suggest that disease is likely a key factor in causing population decline or restricting the distribution of many susceptible Hawaiian species and preventing the recovery of other vulnerable species. The model also provides a framework for the evaluation of factors influencing disease transmission and alternative disease control programs, and to evaluate the impact of climate change on disease cycles and bird populations. ??2011 by the Ecological Society of America.

  3. Dynamic modeling of magnetically insulated transmission line systems

    SciTech Connect

    Mendel, C.W. Jr.; Rosenthal, S.E.

    1996-11-01

    Negative conductors in vacuum transmission lines used in multiterrawatt applications emit electrons freely. These lines are efficient only because the self-magnetic field of the power flow forces the electrons to flow parallel to the electrodes. Excepting numerical simulations, dynamic modeling of systems of these transmission lines has generally either ignored electron flow, or has included only those electrons that cross immediately to the anode at the front of the forward wave. In this paper we describe an analytic model that includes flowing electrons and the effects of these flows on line voltage and on the reduction of magnetic flux. Axial electron currents are modeled using simple, measurable, and calculable parameters. Transverse electron currents are modeled using general patterns found empirically from simulation data. These currents are in turn related by an expanded set of Telegrapher equations. An example of the use of the model is compared to two-dimensional, time-dependent particle-in-cell simulations. {copyright} {ital 1996 American Institute of Physics.}

  4. Seasonality Impact on the Transmission Dynamics of Tuberculosis

    PubMed Central

    2016-01-01

    The statistical data of monthly pulmonary tuberculosis (TB) incidence cases from January 2004 to December 2012 show the seasonality fluctuations in Shaanxi of China. A seasonality TB epidemic model with periodic varying contact rate, reactivation rate, and disease-induced death rate is proposed to explore the impact of seasonality on the transmission dynamics of TB. Simulations show that the basic reproduction number of time-averaged autonomous systems may underestimate or overestimate infection risks in some cases, which may be up to the value of period. The basic reproduction number of the seasonality model is appropriately given, which determines the extinction and uniform persistence of TB disease. If it is less than one, then the disease-free equilibrium is globally asymptotically stable; if it is greater than one, the system at least has a positive periodic solution and the disease will persist. Moreover, numerical simulations demonstrate these theorem results. PMID:27042199

  5. Threshold dynamics of a malaria transmission model in periodic environment

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Teng, Zhidong; Zhang, Tailei

    2013-05-01

    In this paper, we propose a malaria transmission model with periodic environment. The basic reproduction number R0 is computed for the model and it is shown that the disease-free periodic solution of the model is globally asymptotically stable when R0<1, that is, the disease goes extinct when R0<1, while the disease is uniformly persistent and there is at least one positive periodic solution when R0>1. It indicates that R0 is the threshold value determining the extinction and the uniform persistence of the disease. Finally, some examples are given to illustrate the main theoretical results. The numerical simulations show that, when the disease is uniformly persistent, different dynamic behaviors may be found in this model, such as the global attractivity and the chaotic attractor.

  6. Dynamics of a nanodroplet under a transmission electron microscope

    SciTech Connect

    Leong, Fong Yew; Mirsaidov, Utkur M.; Matsudaira, Paul; Mahadevan, L.

    2014-01-15

    We investigate the cyclical stick-slip motion of water nanodroplets on a hydrophilic substrate viewed with and stimulated by a transmission electron microscope. Using a continuum long wave theory, we show how the electrostatic stress imposed by non-uniform charge distribution causes a pinned convex drop to deform into a toroidal shape, with the shape characterized by the competition between the electrostatic stress and the surface tension of the drop, as well as the charge density distribution which follows a Poisson equation. A horizontal gradient in the charge density creates a lateral driving force, which when sufficiently large, overcomes the pinning induced by surface heterogeneities in the substrate disjoining pressure, causing the drop to slide on the substrate via a cyclical stick-slip motion. Our model predicts step-like dynamics in drop displacement and surface area jumps, qualitatively consistent with experimental observations.

  7. X-Ray Transmission Microscope Development

    NASA Technical Reports Server (NTRS)

    Kaukler, William F.

    1997-01-01

    We have succeeded in meeting the goals set out in the proposal. A cadre of detector technologies is available to suit the requirements of the experiment. Resolutions of both real-time and absolute limits to resolution exceed the initial aspirations. Obtaining sufficient contrast is still a significant limitation but can be overcome by Judicious selection of the specimen composition. This can only take time and trial and error for a successful result. The 4th generation furnace provides the capability of real-time in-situ observations of composite alloy development. A low detection sensitivity however, has still made it difficult to observe dendritic growth, although it has been 'seen' in raw video; it was not a recordable signal. We have examined flight ampoules with XTM to observe particle and thermocouple placement, crucible flaws and cracks in collaboration with the Particle Pushing and Engulfment flight experiment (Dr. Stefanescu, UA, P.I.). The value of an in flight XTM to guard against experiment failure and safety assurance is obvious. Although not attributable to equipment limitations, a quest to observe particle pushing was not successful. We tried at length to prepare specimens that would demonstrate particle pushing. Instead, we were successful in imaging the interface deformation due to the thermal field distortion of a ceramic particle or void and to compare to calculated shapes. In theory, we should have been able to make major inroads to this field if the particles could be pushed and the velocities adjusted to make critical measurements. On the other hand, critical issues of sample preparation for the PEP flight experiment were established, particularly the clustering of particles and trapped voids. In this regard, the XTM did prove very useful so that flight specimens would work as expected and to perform post flight analysis. Although not a clear result, particle pushing of precipitates was observed in an Al-Si-Mn alloy. It may be that to be

  8. The influence of engine/transmission/governor on tilting proprotor aircraft dynamics

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1975-01-01

    An analytical model is developed for the dynamics of a tilting proprotor aircraft engine and drive train, including a rotor speed governor and interconnect shaft. The dynamic stability of a proprotor and cantilever wing is calculated, including the engine-transmission-governor model. It is concluded that the rotor behaves much as if windmilling as far as its dynamic behavior is concerned, with some influence of the turboshaft engine inertia and damping. The interconnect shaft has a significant influence on the antisymmetric dynamics of proprotor aircraft. The proprotor aerodynamics model is extended to include reverse flow, and a refinement on the method used to calculate the kinematic pitch-bending coupling of the blade is developed.

  9. Experimental investigation and model development for a harmonic drive transmission.

    SciTech Connect

    Preissner, C.; Shu, D.; Royston, T. J.; Univ. of Illinois at Chicago

    2007-01-01

    Harmonic drive transmissions (HDTs) are compact, low-backlash, high-ratio, high-resolution rotary motion transmissions. One application to benefit from these attributes is the revolute joint robot. Engineers at the Advanced Photon Source (APS) are investigating the use of this type of robot for the positioning of an x-ray detector; understanding the properties of the robot components is crucial to modeling positioner behavior. The robot bearing elements had been investigated previously, leaving the transmission as the missing component. While the benefits of HDTs are well known, the disadvantages, including fluctuating dissipation characteristics and nonlinear stiffness, are not understood as well. These characteristics can contribute uncontrolled dynamics to the overall robot performance. A dynamometer has been constructed at the APS to experimentally measure the HDT's response. Empirical torque and position data were recorded for multiple transmission load cases and input conditions. In turn, a computer model of the dynamometer HDT system was constructed to approximate the observed response.

  10. Hydrologic variability and the dynamics of West Nile virus transmission

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.

    2011-12-01

    West Nile virus (WNV) first emerged in North America in New York City during 1999 and since that time has spread throughout the continent and settled into a pattern of local endemicity in which outbreaks of variable size develop in some years but not others. Predicting where and when these outbreaks will develop is an issue of considerable public health importance. Spillover transmission of WNV to humans typically occurs when infection rates among vector mosquitoes are elevated. Mosquito infection rates are not constant through time but instead increase when newly emergent mosquitoes can more readily acquire WNV by blood-meal feeding on available, infected animal hosts. Such an increase of vector mosquito infection rates is termed amplification and is facilitated for WNV by intense zoonotic transmission of the virus among vector mosquitoes and avian hosts. Theory, observation and model simulations indicate that amplification is favored when mosquito breeding habitats and bird nesting and roosting habitats overlap. Both vector mosquitoes and vertebrate hosts depend on water resources; mosquitoes are critically dependent on the availability of standing water, as the first 3 stages of the mosquito life cycle, egg, larvae, pupae, are aquatic. Here it is shown that hydrologic variability often determines where and when vector mosquitoes and avian hosts congregate together, and when the amplification of WNV is more likely. Measures of land surface wetness and pooling, from ground observation, satellite observation, or numerical modeling, can provide reliable estimates of where and when WNV transmission hotspots will arise. Examples of this linkage between hydrology and WNV activity are given for Florida, Colorado and New York, and an operational system for monitoring and forecasting WNV risk in space and time is presented for Florida.

  11. Transmission dynamics & epidemiology of malaria in two tribal districts in Madhya Pradesh, India

    PubMed Central

    Chand, Gyan; Chaudhary, N.K.; Soan, V.; Kaushal, L.S.; Sharma, R.K.; Singh, Neeru

    2015-01-01

    Background and objectives: Epidemiology and transmission of malaria vary within the tribal areas with the variation in topography, forest cover and type of forest. For the control of disease, understanding of the dynamics of transmission in the varied ecological situation is essential. This study was carried out in the two distinct tribal areas- Baiga Chak (thick forested area) of Dindori district and Bichhia block (forest fringe area) of Mandla district, Madhya Prasdesh, India, to understand the epidemiology and transmission dynamics of malaria. Methods: Mosquitoes were collected using hand catch and whole night collections to determine the proportion of vectors, their density and seasonality. Vector incrimination was done by sporozoite ELISA and feeding preferences of vector by gel diffusion method. Active fever surveys were carried out fortnightly to determine the age specific malaria parasite rates among the inhabitants of two areas. Results: Density of Anopheles culicifacies was significantly higher in Bichhia while the density of An. fluviatilis was higher in Baiga Chak. An. culicifacies was incriminated from both the areas while An. fluviatilis was incriminated from Baiga Chak only. Malaria slide positivity rate (SPR) was significantly higher (OR=3.7 95%CI, 3.1-4.4) in Baiga Chak (28.2%) than Bichhia (9.6%). Interpretation & conclusions: The features of malaria transmission in tribal areas differed from those reported in rural or semirural population. Site-specific and region-specific studies are required to develop appropriate intervention measures to control malaria. PMID:26139772

  12. Modelling inter-human transmission dynamics of Chagas disease: analysis and application.

    PubMed

    Fabrizio, M C; Schweigmann, N J; Bartoloni, N J

    2014-05-01

    Transmission of Trypanosoma cruzi, the causal agent of Chagas disease, has expanded from rural endemic to urban areas due to migration. This so-called urban Chagas is an emerging health problem in American, European, Australian and Japanese cities. We present a mathematical model to analyse the dynamics of urban Chagas to better understand its epidemiology. The model considers the three clinical stages of the disease and the main routes of inter-human transmission. To overcome the complexities of the infection dynamics, the next-generation matrix method was developed. We deduced expressions which allowed estimating the number of new infections generated by an infected individual through each transmission route at each disease stage, the basic reproduction number and the number of individuals at each disease stage at the outbreak of the infection. The analysis was applied to Buenos Aires city (Argentina). We estimated that 94% of the new infections are generated by individuals in the chronic indeterminate stage. When migration was not considered, the infection disappeared slowly and R0 = 0.079, whereas when migration was considered, the number of individuals in each stage of the infection tended to stabilize. The expressions can be used to estimate different numbers of infected individuals in any place where only inter-human transmission is possible. PMID:24533945

  13. Evolution and Use of Dynamic Transmission Models for Measles and Rubella Risk and Policy Analysis.

    PubMed

    Thompson, Kimberly M

    2016-07-01

    The devastation caused by periodic measles outbreaks motivated efforts over more than a century to mathematically model measles disease and transmission. Following the identification of rubella, which similarly presents with fever and rash and causes congenital rubella syndrome (CRS) in infants born to women first infected with rubella early in pregnancy, modelers also began to characterize rubella disease and transmission. Despite the relatively large literature, no comprehensive review to date provides an overview of dynamic transmission models for measles and rubella developed to support risk and policy analysis. This systematic review of the literature identifies quantitative measles and/or rubella dynamic transmission models and characterizes key insights relevant for prospective modeling efforts. Overall, measles and rubella represent some of the relatively simplest viruses to model due to their ability to impact only humans and the apparent life-long immunity that follows survival of infection and/or protection by vaccination, although complexities arise due to maternal antibodies and heterogeneity in mixing and some models considered potential waning immunity and reinfection. This review finds significant underreporting of measles and rubella infections and widespread recognition of the importance of achieving and maintaining high population immunity to stop and prevent measles and rubella transmission. The significantly lower transmissibility of rubella compared to measles implies that all countries could eliminate rubella and CRS by using combination of measles- and rubella-containing vaccines (MRCVs) as they strive to meet regional measles elimination goals, which leads to the recommendation of changing the formulation of national measles-containing vaccines from measles only to MRCV as the standard of care. PMID:27277138

  14. Exploring the dynamics of respiratory syncytial virus (RSV) transmission in children.

    PubMed

    Hogan, Alexandra B; Glass, Kathryn; Moore, Hannah C; Anderssen, Robert S

    2016-08-01

    Respiratory syncytial virus (RSV) is the main cause of lower respiratory tract infections in children. Whilst highly seasonal, RSV dynamics can have either one-year (annual) or two-year (biennial) cycles. Furthermore, some countries show a 'delayed biennial' pattern, where the epidemic peak in low incidence years is delayed. We develop a compartmental model for RSV infection, driven by a seasonal forcing function, and conduct parameter space and bifurcation analyses to document parameter ranges that give rise to these different seasonal patterns. The model is sensitive to the birth rate, transmission rate, and seasonality parameters, and can replicate RSV dynamics observed in different countries. The seasonality parameter must exceed a threshold for the model to produce biennial cycles. Intermediate values of the birth rate produce the greatest delay in these biennial cycles, while the model reverts to annual cycles if the duration of immunity is too short. Finally, the existence of period doubling and period halving bifurcations suggests robust model dynamics, in agreement with the known regularity of RSV outbreaks. These findings help explain observed RSV data, such as regular biennial dynamics in Western Australia, and delayed biennial dynamics in Finland. From a public health perspective, our findings provide insight into the drivers of RSV transmission, and a foundation for exploring RSV interventions. PMID:27155294

  15. Robust transmission stabilization and dynamic switching in broadband hybrid waveguide systems with nonlinear gain and loss

    NASA Astrophysics Data System (ADS)

    Nguyen, Quan M.; Peleg, Avner; Tran, Thinh P.

    2015-01-01

    We develop a method for transmission stabilization and robust dynamic switching for colliding optical soliton sequences in broadband waveguide systems with nonlinear gain and loss. The method is based on employing hybrid waveguides, consisting of spans with linear gain and cubic loss, and spans with linear loss, cubic gain, and quintic loss. We show that the amplitude dynamics is described by a hybrid Lotka-Volterra (LV) model, and use the model to determine the physical parameter values required for enhanced transmission stabilization and switching. Numerical simulations with coupled nonlinear Schrödinger equations confirm the predictions of the LV model, and show complete suppression of radiative instability and pulse distortion. This enables stable transmission over distances larger by an order of magnitude compared with uniform waveguides with linear gain and cubic loss. Moreover, multiple on-off and off-on dynamic switching events are demonstrated over a wide range of soliton amplitudes, showing the superiority of hybrid waveguides compared with static switching in uniform waveguides.

  16. Photocathode Optimization for a Dynamic Transmission Electron Microscope: Final Report

    SciTech Connect

    Ellis, P; Flom, Z; Heinselman, K; Nguyen, T; Tung, S; Haskell, R; Reed, B W; LaGrange, T

    2011-08-04

    The Dynamic Transmission Electron Microscope (DTEM) team at Harvey Mudd College has been sponsored by LLNL to design and build a test setup for optimizing the performance of the DTEM's electron source. Unlike a traditional TEM, the DTEM achieves much faster exposure times by using photoemission from a photocathode to produce electrons for imaging. The DTEM team's work is motivated by the need to improve the coherence and current density of the electron cloud produced by the electron gun in order to increase the image resolution and contrast achievable by DTEM. The photoemission test setup is nearly complete and the team will soon complete baseline tests of electron gun performance. The photoemission laser and high voltage power supply have been repaired; the optics path for relaying the laser to the photocathode has been finalized, assembled, and aligned; the internal setup of the vacuum chamber has been finalized and mostly implemented; and system control, synchronization, and data acquisition has been implemented in LabVIEW. Immediate future work includes determining a consistent alignment procedure to place the laser waist on the photocathode, and taking baseline performance measurements of the tantalum photocathode. Future research will examine the performance of the electron gun as a function of the photoemission laser profile, the photocathode material, and the geometry and voltages of the accelerating and focusing components in the electron gun. This report presents the team's progress and outlines the work that remains.

  17. Transmission Expansion Planning - A Multiyear Dynamic Approach Using a Discrete Evolutionary Particle Swarm Optimization Algorithm

    NASA Astrophysics Data System (ADS)

    Rocha, M. C.; Saraiva, J. T.

    2012-10-01

    The basic objective of Transmission Expansion Planning (TEP) is to schedule a number of transmission projects along an extended planning horizon minimizing the network construction and operational costs while satisfying the requirement of delivering power safely and reliably to load centres along the horizon. This principle is quite simple, but the complexity of the problem and the impact on society transforms TEP on a challenging issue. This paper describes a new approach to solve the dynamic TEP problem, based on an improved discrete integer version of the Evolutionary Particle Swarm Optimization (EPSO) meta-heuristic algorithm. The paper includes sections describing in detail the EPSO enhanced approach, the mathematical formulation of the TEP problem, including the objective function and the constraints, and a section devoted to the application of the developed approach to this problem. Finally, the use of the developed approach is illustrated using a case study based on the IEEE 24 bus 38 branch test system.

  18. Selective Maturation of Temporal Dynamics of Intracortical Excitatory Transmission at the Critical Period Onset.

    PubMed

    Miao, Qinglong; Yao, Li; Rasch, Malte J; Ye, Qian; Li, Xiang; Zhang, Xiaohui

    2016-08-01

    Although the developmental maturation of cortical inhibitory synapses is known to be a critical factor in gating the onset of critical period (CP) for experience-dependent cortical plasticity, how synaptic transmission dynamics of other cortical synapses are regulated during the transition to CP remains unknown. Here, by systematically examining various intracortical synapses within layer 4 of the mouse visual cortex, we demonstrate that synaptic temporal dynamics of intracortical excitatory synapses on principal cells (PCs) and inhibitory parvalbumin- or somatostatin-expressing cells are selectively regulated before the CP onset, whereas those of intracortical inhibitory synapses and long-range thalamocortical excitatory synapses remain unchanged. This selective maturation of synaptic dynamics results from a ubiquitous reduction of presynaptic release and is dependent on visual experience. These findings provide an additional essential circuit mechanism for regulating CP timing in the developing visual cortex. PMID:27477277

  19. Geared rotor dynamic methodologies for advancing prognostic modeling capabilities in rotary-wing transmission systems

    NASA Astrophysics Data System (ADS)

    Stringer, David Blake

    The overarching objective in this research is the development of a robust, rotor dynamic, physics based model of a helicopter drive train as a foundation for the prognostic modeling for rotary-wing transmissions. Rotorcrafts rely on the integrity of their drive trains for their airworthiness. Drive trains rely on gear technology for their integrity and function. Gears alter the vibration characteristics of a mechanical system and significantly contribute to noise, component fatigue, and personal discomfort prevalent in rotorcraft. This research effort develops methodologies for generating a rotor dynamic model of a rotary-wing transmission based on first principles, through (i) development of a three-dimensional gear-mesh stiffness model for helical and spur gears and integration of this model in a finite element rotor dynamic model, (ii) linear and nonlinear analyses of a geared system for comparison and validation of the gear-mesh model, (iii) development of a modal synthesis technique for potentially providing model reduction and faster analysis capabilities for geared systems, and (iv) extension of the gear-mesh model to bevel and epicyclic configurations. In addition to model construction and validation, faults indigenous to geared systems are presented and discussed. Two faults are selected for analysis and seeded into the transmission model. Diagnostic vibration parameters are presented and used as damage indicators in the analysis. The fault models produce results consistent with damage experienced during experimental testing. The results of this research demonstrate the robustness of the physics-based approach in simulating multiple normal and abnormal conditions. The advantages of this physics-based approach, when combined with contemporary probabilistic and time-series techniques, provide a useful method for improving health monitoring technologies in mechanical systems.

  20. Environmental transmission of Mycobacterium ulcerans drives dynamics of Buruli ulcer in endemic regions of Cameroon

    NASA Astrophysics Data System (ADS)

    Garchitorena, Andrés; Ngonghala, Calistus N.; Texier, Gaëtan; Landier, Jordi; Eyangoh, Sara; Bonds, Matthew H.; Guégan, Jean-François; Roche, Benjamin

    2015-12-01

    Buruli Ulcer is a devastating skin disease caused by the pathogen Mycobacterium ulcerans. Emergence and distribution of Buruli ulcer cases is clearly linked to aquatic ecosystems, but the specific route of transmission of M. ulcerans to humans remains unclear. Relying on the most detailed field data in space and time on M. ulcerans and Buruli ulcer available today, we assess the relative contribution of two potential transmission routes -environmental and water bug transmission- to the dynamics of Buruli ulcer in two endemic regions of Cameroon. The temporal dynamics of Buruli ulcer incidence are explained by estimating rates of different routes of transmission in mathematical models. Independently, we also estimate statistical models of the different transmission pathways on the spatial distribution of Buruli ulcer. The results of these two independent approaches are corroborative and suggest that environmental transmission pathways explain the temporal and spatial patterns of Buruli ulcer in our endemic areas better than the water bug transmission.

  1. Variations in Modeled Dengue Transmission over Puerto Rico Using a Climate Driven Dynamic Model

    NASA Technical Reports Server (NTRS)

    Morin, Cory; Monaghan, Andrew; Crosson, William; Quattrochi, Dale; Luvall, Jeffrey

    2014-01-01

    Dengue fever is a mosquito-borne viral disease reemerging throughout much of the tropical Americas. Dengue virus transmission is explicitly influenced by climate and the environment through its primary vector, Aedes aegypti. Temperature regulates Ae. aegypti development, survival, and replication rates as well as the incubation period of the virus within the mosquito. Precipitation provides water for many of the preferred breeding habitats of the mosquito, including buckets, old tires, and other places water can collect. Because of variations in topography, ocean influences and atmospheric processes, temperature and rainfall patterns vary across Puerto Rico and so do dengue virus transmission rates. Using NASA's TRMM (Tropical Rainfall Measuring Mission) satellite for precipitation input, ground-based observations for temperature input, and laboratory confirmed dengue cases reported by the Centers for Disease Control and Prevention for parameter calibration, we modeled dengue transmission at the county level across Puerto Rico from 2010-2013 using a dynamic dengue transmission model that includes interacting vector ecology and epidemiological components. Employing a Monte Carlo approach, we performed ensembles of several thousands of model simulations for each county in order to resolve the model uncertainty arising from using different combinations of parameter values that are not well known. The top 1% of model simulations that best reproduced the reported dengue case data were then analyzed to determine the most important parameters for dengue virus transmission in each county, as well as the relative influence of climate variability on transmission. These results can be used by public health workers to implement dengue control methods that are targeted for specific locations and climate conditions.

  2. The effect of temperature on Anopheles mosquito population dynamics and the potential for malaria transmission.

    PubMed

    Beck-Johnson, Lindsay M; Nelson, William A; Paaijmans, Krijn P; Read, Andrew F; Thomas, Matthew B; Bjørnstad, Ottar N

    2013-01-01

    The parasites that cause malaria depend on Anopheles mosquitoes for transmission; because of this, mosquito population dynamics are a key determinant of malaria risk. Development and survival rates of both the Anopheles mosquitoes and the Plasmodium parasites that cause malaria depend on temperature, making this a potential driver of mosquito population dynamics and malaria transmission. We developed a temperature-dependent, stage-structured delayed differential equation model to better understand how climate determines risk. Including the full mosquito life cycle in the model reveals that the mosquito population abundance is more sensitive to temperature than previously thought because it is strongly influenced by the dynamics of the juvenile mosquito stages whose vital rates are also temperature-dependent. Additionally, the model predicts a peak in abundance of mosquitoes old enough to vector malaria at more accurate temperatures than previous models. Our results point to the importance of incorporating detailed vector biology into models for predicting the risk for vector borne diseases. PMID:24244467

  3. Detection of allosteric signal transmission by information-theoretic analysis of protein dynamics.

    PubMed

    Pandini, Alessandro; Fornili, Arianna; Fraternali, Franca; Kleinjung, Jens

    2012-02-01

    Allostery offers a highly specific way to modulate protein function. Therefore, understanding this mechanism is of increasing interest for protein science and drug discovery. However, allosteric signal transmission is difficult to detect experimentally and to model because it is often mediated by local structural changes propagating along multiple pathways. To address this, we developed a method to identify communication pathways by an information-theoretical analysis of molecular dynamics simulations. Signal propagation was described as information exchange through a network of correlated local motions, modeled as transitions between canonical states of protein fragments. The method was used to describe allostery in two-component regulatory systems. In particular, the transmission from the allosteric site to the signaling surface of the receiver domain NtrC was shown to be mediated by a layer of hub residues. The location of hubs preferentially connected to the allosteric site was found in close agreement with key residues experimentally identified as involved in the signal transmission. The comparison with the networks of the homologues CheY and FixJ highlighted similarities in their dynamics. In particular, we showed that a preorganized network of fragment connections between the allosteric and functional sites exists already in the inactive state of all three proteins. PMID:22071506

  4. Conceptual Framework and Research Methods for Migration and HIV Transmission Dynamics

    PubMed Central

    Cassels, Susan; Jenness, Samuel M.; Khanna, Aditya

    2014-01-01

    Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic. PMID:24257897

  5. Conceptual framework and research methods for migration and HIV transmission dynamics.

    PubMed

    Cassels, Susan; Jenness, Samuel M; Khanna, Aditya S

    2014-12-01

    Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic. PMID:24257897

  6. Numerical modeling of the transmission dynamics of drug-sensitive and drug-resistant HSV-2

    NASA Astrophysics Data System (ADS)

    Gumel, A. B.

    2001-03-01

    A competitive finite-difference method will be constructed and used to solve a modified deterministic model for the spread of herpes simplex virus type-2 (HSV-2) within a given population. The model monitors the transmission dynamics and control of drug-sensitive and drug-resistant HSV-2. Unlike the fourth-order Runge-Kutta method (RK4), which fails when the discretization parameters exceed certain values, the novel numerical method to be developed in this paper gives convergent results for all parameter values.

  7. Observations of Nanobubble Dynamics with Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Mohan, Meera Kanakamma; Arora, Manish; Mirsaidov, Utkur; Ohl, Claus-Dieter

    2013-11-01

    Recent developments in transmission electron microscopy (TEM) allow the imaging of liquids with high spatial resolution. Here we report on novel studies of water trapped between two monolayers of graphene sheets. The geometry prevents evaporation of the liquid into the low pressure environment of the TEM while providing excellent electron-optical properties for investigations. The graphene sheets are supported by a conventional TEM grid. We report on the nucleation of bubbles, the coalescence between neighbouring bubbles, rupture of thin liquid filaments, and their slow shrinkage. At a dose rate of 100-155 e-Å-2s-1 these events are observed conveniently at video frame rate. The correlation with the local electron beam dose rate suggests that the radiolysis induced by the electron beam is the main driving force for most events. In general, we observed bubbles with lateral sizes between 20 nm and 100 nm and estimated heights between 6 nm and 30 nm. Likely, the bubbles connect both graphene sheets. In the absence of the electron beam the nanobubbles do not dissolve completely but surprisingly remain stable for even up to one hour. This resembles the stability of surface attached nanobubbles.

  8. Development of transmission error tester for face gears

    NASA Astrophysics Data System (ADS)

    Shi, Zhao-yao; Lu, Xiao-ning; Chen, Chang-he; Lin, Jia-chun

    2013-10-01

    A tester for measuring face gears' transmission error was developed based on single-flank rolling principle. The mechanical host was of hybrid configuration of the vertical and horizontal structures. The tester is mainly constituted by base, precision spindle, grating measurement system and control unit. The structure of precision spindles was designed, and rotation accuracy of the spindleswas improved. The key techniques, such as clamping, positioning and adjustment of the gears were researched. In order to collect the data of transmission error, high-frequency clock pulse subdivision count method with higher measurement resolution was proposed. The developed tester can inspect the following errors, such as transmission error of the pair, tangential composite deviation for the measured face gear, pitch deviation, eccentricity error, and so on. The results of measurement can be analyzed by the tester; The tester can meet face gear quality testing requirements for accuracy of grade 5.

  9. Mathematical Model of Three Age-Structured Transmission Dynamics of Chikungunya Virus

    PubMed Central

    Agusto, Folashade B.; Easley, Shamise; Freeman, Kenneth; Thomas, Madison

    2016-01-01

    We developed a new age-structured deterministic model for the transmission dynamics of chikungunya virus. The model is analyzed to gain insights into the qualitative features of its associated equilibria. Some of the theoretical and epidemiological findings indicate that the stable disease-free equilibrium is globally asymptotically stable when the associated reproduction number is less than unity. Furthermore, the model undergoes, in the presence of disease induced mortality, the phenomenon of backward bifurcation, where the stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the associated reproduction number is less than unity. Further analysis of the model indicates that the qualitative dynamics of the model are not altered by the inclusion of age structure. This is further emphasized by the sensitivity analysis results, which shows that the dominant parameters of the model are not altered by the inclusion of age structure. However, the numerical simulations show the flaw of the exclusion of age in the transmission dynamics of chikungunya with regard to control implementations. The exclusion of age structure fails to show the age distribution needed for an effective age based control strategy, leading to a one size fits all blanket control for the entire population. PMID:27190548

  10. Fluid dynamics of heart development.

    PubMed

    Santhanakrishnan, Arvind; Miller, Laura A

    2011-09-01

    The morphology, muscle mechanics, fluid dynamics, conduction properties, and molecular biology of the developing embryonic heart have received much attention in recent years due to the importance of both fluid and elastic forces in shaping the heart as well as the striking relationship between the heart's evolution and development. Although few studies have directly addressed the connection between fluid dynamics and heart development, a number of studies suggest that fluids may play a key role in morphogenic signaling. For example, fluid shear stress may trigger biochemical cascades within the endothelial cells of the developing heart that regulate chamber and valve morphogenesis. Myocardial activity generates forces on the intracardiac blood, creating pressure gradients across the cardiac wall. These pressures may also serve as epigenetic signals. In this article, the fluid dynamics of the early stages of heart development is reviewed. The relevant work in cardiac morphology, muscle mechanics, regulatory networks, and electrophysiology is also reviewed in the context of intracardial fluid dynamics. PMID:21327946

  11. Environmental transmission of Mycobacterium ulcerans drives dynamics of Buruli ulcer in endemic regions of Cameroon

    PubMed Central

    Garchitorena, Andrés; Ngonghala, Calistus N.; Texier, Gaëtan; Landier, Jordi; Eyangoh, Sara; Bonds, Matthew H.; Guégan, Jean-François; Roche, Benjamin

    2015-01-01

    Buruli Ulcer is a devastating skin disease caused by the pathogen Mycobacterium ulcerans. Emergence and distribution of Buruli ulcer cases is clearly linked to aquatic ecosystems, but the specific route of transmission of M. ulcerans to humans remains unclear. Relying on the most detailed field data in space and time on M. ulcerans and Buruli ulcer available today, we assess the relative contribution of two potential transmission routes –environmental and water bug transmission– to the dynamics of Buruli ulcer in two endemic regions of Cameroon. The temporal dynamics of Buruli ulcer incidence are explained by estimating rates of different routes of transmission in mathematical models. Independently, we also estimate statistical models of the different transmission pathways on the spatial distribution of Buruli ulcer. The results of these two independent approaches are corroborative and suggest that environmental transmission pathways explain the temporal and spatial patterns of Buruli ulcer in our endemic areas better than the water bug transmission. PMID:26658922

  12. Understanding myxozoan infection dynamics in the sea: seasonality and transmission of Ceratomyxa puntazzi.

    PubMed

    Alama-Bermejo, Gema; Šíma, Radek; Raga, Juan A; Holzer, Astrid S

    2013-08-01

    Ceratomyxa puntazzi affects the sharpsnout seabream, Diplodus puntazzo, a recently explored aquaculture species in the Mediterranean. Little is known about the transmission and seasonality of marine myxozoans, although this knowledge is of considerable importance for the design of management strategies for aquaculture. In the present study on C. puntazzi we investigated the potential pathways of transmission as well as the parasite abundance in fish and its density in environmental water samples, throughout a full year. We performed monthly sentinel fish exposures in a C. puntazzi enzootic environment and quantified waterborne stages in seawater. Two novel C. puntazzi-specific PCR and quantitative PCR assays were developed to determine infection levels in fish and water samples. Ceratomyxa puntazzi presents marked seasonal changes in parasite density, with a double-peaked prevalence of infection in sentinel fish in spring and late summer/autumn, at 16-24°C, and a covert infection during the winter months. Invasive blood stages were detected all year round by PCR. The combination of sentinel fish exposure with the quantification of waterborne stages allowed us to attribute this pattern in C. puntazzi density to higher numbers of actinospores in the water, while myxospores are predominant in summer and winter. We demonstrated that temperature increase triggered actinospore production in the invertebrate host in a benthic habitat and we suggest that the life cycle dynamics of the invertebrate host explain the double-peaked infection prevalence in fish. Experimental transmission of different C. puntazzi developmental stages in seawater or by oral and intracoelomic injection was unsuccessful which indicates fish-to-fish transmission is unlikely to occur in aquaculture systems. This is the first model studying seasonality and infection dynamics of a marine myxozoan. PMID:23747926

  13. Developing cryotherapy to eliminate graft-transmissible pathogens in citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article summarizes research being conducted as part of a project funded by the California Citrus Research Board to develop cryotherapy (freezing buds in liquid nitrogen, and then recovering them) as a viable method for elimination of graft transmissible pathogens from Citrus. There are current...

  14. HIV Infection: Transmission, Effects on Early Development, and Interventions.

    ERIC Educational Resources Information Center

    Lowenthal, Barbara

    1997-01-01

    Describes the modes of transmission of HIV and the course of the disease in infants and toddlers. Information is provided on its effects on early development, medical screening and treatments, therapies, psychosocial assistance, and interventions, including nutritional therapy, occupational and physical therapies, and speech and language therapy.…

  15. Neodymium neutron transmission and capture measurements and development of a new transmission detector

    NASA Astrophysics Data System (ADS)

    Barry, Devin P.

    to finding improved resolution function parameters, a method was developed to find the 'estimated uncertainty' on these parameters. The 'estimated uncertainty' values for the resolution function parameters were chosen to represent a + or -10% change in the reduced chi-squared value in fits to uranium. This thesis also presents the design, construction, and implementation of a new out-of-beam detector (OBD) system for use in transmission experiments. MCNP modeling was used to validate that the OBD system has less neutron backscatter when compared with the previously used in-beam detector (IBD). This decrease in neutron backscatter offers an overall improvement in resolution function. Experiments were performed with the OBD system using uranium samples and resulting data was used to show this improvement in the resolution function.

  16. Transmission Dynamics of the Recently-Identified BYD Virus Causing Duck Egg-Drop Syndrome

    PubMed Central

    Vaidya, Naveen K.; Wang, Feng-bin; Zou, Xingfu; Wahl, Lindi M.

    2012-01-01

    Baiyangdian (BYD) virus is a recently-identified mosquito-borne flavivirus that causes severe disease in ducks, with extremely rapid transmission, up to 15% mortality within 10 days and 90% reduction in egg production on duck farms within 5 days of infection. Because of the zoonotic nature of flaviviruses, the characterization of BYD virus and its epidemiology are important public health concerns. Here, we develop a mathematical model for the transmission dynamics of this novel virus. We validate the model against BYD outbreak data collected from duck farms in Southeast China, as well as experimental data obtained from an animal facility. Based on our model, the basic reproductive number of BYD virus is high (R0 = 21) indicating that this virus is highly transmissible, consistent with the dramatic epidemiology observed in BYDV-affected duck farms. Our results indicate that younger ducks are more vulnerable to BYD disease and that ducks infected with BYD virus reduce egg production (to about 33% on average) for about 3 days post-infection; after 3 days infected ducks are no longer able to produce eggs. Using our model, we predict that control measures which reduce contact between mosquitoes and ducks such as mosquito nets are more effective than insecticides. PMID:22529985

  17. Transmission dynamics of the recently-identified BYD virus causing duck egg-drop syndrome.

    PubMed

    Vaidya, Naveen K; Wang, Feng-bin; Zou, Xingfu; Wahl, Lindi M

    2012-01-01

    Baiyangdian (BYD) virus is a recently-identified mosquito-borne flavivirus that causes severe disease in ducks, with extremely rapid transmission, up to 15% mortality within 10 days and 90% reduction in egg production on duck farms within 5 days of infection. Because of the zoonotic nature of flaviviruses, the characterization of BYD virus and its epidemiology are important public health concerns. Here, we develop a mathematical model for the transmission dynamics of this novel virus. We validate the model against BYD outbreak data collected from duck farms in Southeast China, as well as experimental data obtained from an animal facility. Based on our model, the basic reproductive number of BYD virus is high (R(0) = 21) indicating that this virus is highly transmissible, consistent with the dramatic epidemiology observed in BYDV-affected duck farms. Our results indicate that younger ducks are more vulnerable to BYD disease and that ducks infected with BYD virus reduce egg production (to about 33% on average) for about 3 days post-infection; after 3 days infected ducks are no longer able to produce eggs. Using our model, we predict that control measures which reduce contact between mosquitoes and ducks such as mosquito nets are more effective than insecticides. PMID:22529985

  18. Cost-effectiveness of influenza control measures: a dynamic transmission model-based analysis.

    PubMed

    Chen, S-C; Liao, C-M

    2013-12-01

    We investigated the cost-effectiveness of different influenza control strategies in a school setting in Taiwan. A susceptible-exposure-infected-recovery (SEIR) model was used to simulate influenza transmission and we used a basic reproduction number (R 0)-asymptomatic proportion (θ) control scheme to develop a cost-effectiveness model. Based on our dynamic transmission model and economic evaluation, this study indicated that the optimal cost-effective strategy for all modelling scenarios was a combination of natural ventilation and respiratory masking. The estimated costs were US$10/year per person in winter for one kindergarten student. The cost for hand washing was estimated to be US$32/year per person, which was much lower than that of isolation (US$55/year per person) and vaccination (US$86/year per person) in containing seasonal influenza. Transmission model-based, cost-effectiveness analysis can be a useful tool for providing insight into the impacts of economic factors and health benefits on certain strategies for controlling seasonal influenza. PMID:23481024

  19. Characterizing the Transmission Dynamics and Control of Ebola Virus Disease

    PubMed Central

    Chowell, Gerardo; Nishiura, Hiroshi

    2015-01-01

    Carefully calibrated transmission models have the potential to guide public health officials on the nature and scale of the interventions required to control epidemics. In the context of the ongoing Ebola virus disease (EVD) epidemic in Liberia, Drake and colleagues, in this issue of PLOS Biology, employed an elegant modeling approach to capture the distributions of the number of secondary cases that arise in the community and health care settings in the context of changing population behaviors and increasing hospital capacity. Their findings underscore the role of increasing the rate of safe burials and the fractions of infectious individuals who seek hospitalization together with hospital capacity to achieve epidemic control. However, further modeling efforts of EVD transmission and control in West Africa should utilize the spatial-temporal patterns of spread in the region by incorporating spatial heterogeneity in the transmission process. Detailed datasets are urgently needed to characterize temporal changes in population behaviors, contact networks at different spatial scales, population mobility patterns, adherence to infection control measures in hospital settings, and hospitalization and reporting rates. PMID:25607595

  20. Characterizing the transmission dynamics and control of ebola virus disease.

    PubMed

    Chowell, Gerardo; Nishiura, Hiroshi

    2015-01-01

    Carefully calibrated transmission models have the potential to guide public health officials on the nature and scale of the interventions required to control epidemics. In the context of the ongoing Ebola virus disease (EVD) epidemic in Liberia, Drake and colleagues, in this issue of PLOS Biology, employed an elegant modeling approach to capture the distributions of the number of secondary cases that arise in the community and health care settings in the context of changing population behaviors and increasing hospital capacity. Their findings underscore the role of increasing the rate of safe burials and the fractions of infectious individuals who seek hospitalization together with hospital capacity to achieve epidemic control. However, further modeling efforts of EVD transmission and control in West Africa should utilize the spatial-temporal patterns of spread in the region by incorporating spatial heterogeneity in the transmission process. Detailed datasets are urgently needed to characterize temporal changes in population behaviors, contact networks at different spatial scales, population mobility patterns, adherence to infection control measures in hospital settings, and hospitalization and reporting rates. PMID:25607595

  1. SSME structural dynamic model development

    NASA Technical Reports Server (NTRS)

    Foley, M. J.; Tilley, D. M.; Welch, C. T.

    1983-01-01

    A mathematical model of the Space Shuttle Main Engine (SSME) as a complete assembly, with detailed emphasis on LOX and High Fuel Turbopumps is developed. The advantages of both complete engine dynamics, and high fidelity modeling are incorporated. Development of this model, some results, and projected applications are discussed.

  2. Practical aspects of monochromators developed for transmission electron microscopy

    PubMed Central

    Kimoto, Koji

    2014-01-01

    A few practical aspects of monochromators recently developed for transmission electron microscopy are briefly reviewed. The basic structures and properties of four monochromators, a single Wien filter monochromator, a double Wien filter monochromator, an omega-shaped electrostatic monochromator and an alpha-shaped magnetic monochromator, are outlined. The advantages and side effects of these monochromators in spectroscopy and imaging are pointed out. A few properties of the monochromators in imaging, such as spatial or angular chromaticity, are also discussed. PMID:25125333

  3. Wet cells and dry cells: In situ transmission electron microscopy of electrically-driven, dynamical processes

    NASA Astrophysics Data System (ADS)

    White, Edward Robert, IV

    Recent developments in nanofabrication techniques allow thin, wet systems to be imaged with high spatial and temporal resolution in the electron microscope. Coupling this ability with simultaneous, measured, electrical control, we cycle processes in liquid systems representing different electrochemical battery components. Dynamic processes imaged with these techniques, which represent a new state-of-the-art, include nanobubble collapse, dendrite growth, ion diffusion, and graphite intercalation. We also develop a sensitive system for measuring electron beam induced currents (EBIC) in the transmission electron microscope and apply it to graphene-MoS2 heterostructures. This new hybrid material has strong light-matter interactions, and the EBIC measurements map the minority carrier diffusion length, which we observe to decrease with increasing radiation damage. These results have direct implications for the function and service lifetime of solar cells based on molybdenum disulfide.

  4. Transmission Dynamics and Control of Severe Acute Respiratory Syndrome

    NASA Astrophysics Data System (ADS)

    Lipsitch, Marc; Cohen, Ted; Cooper, Ben; Robins, James M.; Ma, Stefan; James, Lyn; Gopalakrishna, Gowri; Chew, Suok Kai; Tan, Chorh Chuan; Samore, Matthew H.; Fisman, David; Murray, Megan

    2003-06-01

    Severe acute respiratory syndrome (SARS) is a recently described illness of humans that has spread widely over the past 6 months. With the use of detailed epidemiologic data from Singapore and epidemic curves from other settings, we estimated the reproductive number for SARS in the absence of interventions and in the presence of control efforts. We estimate that a single infectious case of SARS will infect about three secondary cases in a population that has not yet instituted control measures. Public-health efforts to reduce transmission are expected to have a substantial impact on reducing the size of the epidemic.

  5. Leaf transmission reduction using moving jaws for dynamic MLC IMRT

    SciTech Connect

    Schmidhalter, D.; Fix, M. K.; Niederer, P.; Mini, R.; Manser, P.

    2007-09-15

    The aim of this work is to investigate to what extent it is possible to use the secondary collimator jaws to reduce the transmitted radiation through the multileaf collimator (MLC) during an intensity modulated radiation therapy (IMRT). A method is developed and introduced where the jaws follow the open window of the MLC dynamically (dJAW method). With the aid of three academic cases (Closed MLC, Sliding-gap, and Chair) and two clinical cases (prostate and head and neck) the feasibility of the dJAW method and the influence of this method on the applied dose distributions are investigated. For this purpose the treatment planning system Eclipse and the Research-Toolbox were used as well as measurements within a solid water phantom were performed. The transmitted radiation through the closed MLC leads to an inhomogeneous dose distribution. In this case, the measured dose within a plane perpendicular to the central axis differs up to 40% (referring to the maximum dose within this plane) for 6 and 15 MV. The calculated dose with Eclipse is clearly more homogeneous. For the Sliding-gap case this difference is still up to 9%. Among other things, these differences depend on the depth of the measurement within the solid water phantom and on the application method. In the Chair case, the dose in regions where no dose is desired is locally reduced by up to 50% using the dJAW method instead of the conventional method. The dose inside the chair-shaped region decreased up to 4% if the same number of monitor units (MU) as for the conventional method was applied. The undesired dose in the volume body minus the planning target volume in the clinical cases prostate and head and neck decreased up to 1.8% and 1.5%, while the number of the applied MU increased up to 3.1% and 2.8%, respectively. The new dJAW method has the potential to enhance the optimization of the conventional IMRT to a further step.

  6. The genealogical population dynamics of HIV-1 in a large transmission chain: bridging within and among host evolutionary rates.

    PubMed

    Vrancken, Bram; Rambaut, Andrew; Suchard, Marc A; Drummond, Alexei; Baele, Guy; Derdelinckx, Inge; Van Wijngaerden, Eric; Vandamme, Anne-Mieke; Van Laethem, Kristel; Lemey, Philippe

    2014-04-01

    Transmission lies at the interface of human immunodeficiency virus type 1 (HIV-1) evolution within and among hosts and separates distinct selective pressures that impose differences in both the mode of diversification and the tempo of evolution. In the absence of comprehensive direct comparative analyses of the evolutionary processes at different biological scales, our understanding of how fast within-host HIV-1 evolutionary rates translate to lower rates at the between host level remains incomplete. Here, we address this by analyzing pol and env data from a large HIV-1 subtype C transmission chain for which both the timing and the direction is known for most transmission events. To this purpose, we develop a new transmission model in a Bayesian genealogical inference framework and demonstrate how to constrain the viral evolutionary history to be compatible with the transmission history while simultaneously inferring the within-host evolutionary and population dynamics. We show that accommodating a transmission bottleneck affords the best fit our data, but the sparse within-host HIV-1 sampling prevents accurate quantification of the concomitant loss in genetic diversity. We draw inference under the transmission model to estimate HIV-1 evolutionary rates among epidemiologically-related patients and demonstrate that they lie in between fast intra-host rates and lower rates among epidemiologically unrelated individuals infected with HIV subtype C. Using a new molecular clock approach, we quantify and find support for a lower evolutionary rate along branches that accommodate a transmission event or branches that represent the entire backbone of transmitted lineages in our transmission history. Finally, we recover the rate differences at the different biological scales for both synonymous and non-synonymous substitution rates, which is only compatible with the 'store and retrieve' hypothesis positing that viruses stored early in latently infected cells preferentially

  7. On transmission errors and profile modifications minimising dynamic tooth loads in multi-mesh gears

    NASA Astrophysics Data System (ADS)

    Velex, Ph.; Chapron, M.; Fakhfakh, H.; Bruyère, J.; Becquerelle, S.

    2016-09-01

    A modular three-dimensional model of multi-mesh gears is used to analyse theoretically the link between dynamic mesh excitations and transmission errors. It is demonstrated that dynamic mesh forces are mostly controlled by the local transmission errors associated with each individual mesh. A design criterion is derived which can be used to define the tooth shape modifications minimising dynamic tooth loads. The results from two examples of application on idler and planetary systems prove that the proposed theory is sound and can be applied to a variety of gear geometries. Finally, the interest and limits of using transmission errors from a single pinion-gear pair in the context of multi-mesh gears are discussed.

  8. Backward bifurcation and control in transmission dynamics of arboviral diseases.

    PubMed

    Abboubakar, Hamadjam; Claude Kamgang, Jean; Tieudjo, Daniel

    2016-08-01

    In this paper, we derive and analyze a compartmental model for the control of arboviral diseases which takes into account an imperfect vaccine combined with individual protection and some vector control strategies already studied in the literature. After the formulation of the model, a qualitative study based on stability analysis and bifurcation theory reveals that the phenomenon of backward bifurcation may occur. The stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the reproduction number, R0, is less than unity. Using Lyapunov function theory, we prove that the trivial equilibrium is globally asymptotically stable. When the disease-induced death is not considered, or/and, when the standard incidence is replaced by the mass action incidence, the backward bifurcation does not occur. Under a certain condition, we establish the global asymptotic stability of the disease-free equilibrium of the principal model. Through sensitivity analysis, we determine the relative importance of model parameters for disease transmission. Numerical simulations show that the combination of several control mechanisms would significantly reduce the spread of the disease, if we maintain the level of each control high, and this, over a long period. PMID:27321192

  9. Transmission blocking malaria vaccines: Assays and candidates in clinical development.

    PubMed

    Sauerwein, R W; Bousema, T

    2015-12-22

    Stimulated by recent advances in malaria control and increased funding, the elimination of malaria is now considered to be an attainable goal for an increasing number of malaria-endemic regions. This has boosted the interest in transmission-reducing interventions including vaccines that target sexual, sporogenic, and/or mosquito-stage antigens to interrupt malaria transmission (SSM-VIMT). SSM-VIMT aim to prevent human malaria infection in vaccinated communities by inhibiting parasite development within the mosquito after a blood meal taken from a gametocyte carrier. Only a handful of target antigens are in clinical development and progress has been slow over the years. Major stumbling blocks include (i) the expression of appropriately folded target proteins and their downstream purification, (ii) insufficient induction of sustained functional blocking antibody titers by candidate vaccines in humans, and (iii) validation of a number of (bio)-assays as correlate for blocking activity in the field. Here we discuss clinical manufacturing and testing of current SSM-VIMT candidates and the latest bio-assay development for clinical evaluation. New testing strategies are discussed that may accelerate the evaluation and application of SSM-VIMT. PMID:26409813

  10. Engineering science research issues in high power density transmission dynamics for aerospace applications. [rotorcraft geared rotors

    NASA Technical Reports Server (NTRS)

    Singh, Rajendra; Houser, Donald R.

    1993-01-01

    This paper discusses analytical and experimental approaches that will be needed to understand dynamic, vibro-acoustic and design characteristics of high power density rotorcraft transmissions. Complexities associated with mathematical modeling of such systems will be discussed. An overview of research work planned during the next several years will be presented, with emphasis on engineering science issues such as gear contact mechanics, multi-mesh drive dynamics, parameter uncertainties, vibration transmission through bearings, and vibro-acoustic characteristics of geared rotor systems and housing-mount structures. A few examples of work in progress are cited.

  11. Telomere Dynamics and Homeostasis in a Transmissible Cancer

    PubMed Central

    Ujvari, Beata; Pearse, Anne-Maree; Taylor, Robyn; Pyecroft, Stephen; Flanagan, Cassandra; Gombert, Sara; Papenfuss, Anthony T.; Madsen, Thomas; Belov, Katherine

    2012-01-01

    Background Devil Facial Tumour Disease (DFTD) is a unique clonal cancer that threatens the world's largest carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii) with extinction. This transmissible cancer is passed between individual devils by cell implantation during social interactions. The tumour arose in a Schwann cell of a single devil over 15 years ago and since then has expanded clonally, without showing signs of replicative senescence; in stark contrast to a somatic cell that displays a finite capacity for replication, known as the “Hayflick limit”. Methodology/Principal Findings In the present study we investigate the role of telomere length, measured as Telomere Copy Number (TCN), and telomerase and shelterin gene expression, as well as telomerase activity in maintaining hyperproliferation of Devil Facial Tumour (DFT) cells. Our results show that DFT cells have short telomeres. DFTD TCN does not differ between geographic regions or between strains. However, TCN has increased over time. Unlimited cell proliferation is likely to have been achieved through the observed up-regulation of the catalytic subunit of telomerase (TERT) and concomitant activation of telomerase. Up-regulation of the central component of shelterin, the TRF1-intercating nuclear factor 2 (TINF2) provides DFT a mechanism for telomere length homeostasis. The higher expression of both TERT and TINF2 may also protect DFT cells from genomic instability and enhance tumour proliferation. Conclusions/Significance DFT cells appear to monitor and regulate the length of individual telomeres: i.e. shorter telomeres are elongated by up-regulation of telomerase-related genes; longer telomeres are protected from further elongation by members of the shelterin complex, which may explain the lack of spatial and strain variation in DFT telomere copy number. The observed longitudinal increase in gene expression in DFT tissue samples and telomerase activity in DFT cell lines might indicate a

  12. Epigenetic Dynamics During Preimplantation Development

    PubMed Central

    Marcho, Chelsea; Cui, Wei; Mager, Jesse

    2015-01-01

    Successful mammalian development requires descendants of single-cell zygotes to differentiate into diverse cell types even though they contain the same genetic material. Preimplantation dynamics are first driven by the necessity of reprogramming haploid parental epigenomes to reach a totipotent state. This process requires extensive erasure of epigenetic marks shortly after fertilization. During the few short days after formation of the zygote, epigenetic programs are established and are essential for the first lineage decisions and differentiation. Here we review the current understanding of DNA methylation and histone modification dynamics responsible for these early changes during mammalian preimplantation development. In particular we highlight insights that have been gained through next generation sequencing technologies comparing human embryos to other models as well as the recent discoveries of active DNA demethylation mechanisms at play during preimplantation. PMID:26031750

  13. Impact of environmental stressors on the dynamics of disease transmission.

    PubMed

    Loge, Frank J; Arkoosh, Mary R; Ginn, Timothy R; Johnson, Lyndal L; Collier, Tracy K

    2005-09-15

    Infectious disease within outmigrant juvenile salmon in the Columbia River Basin is modulated, in part, by abiotic stressors that influence host-susceptibility. Through the application of a dose-structured population dynamic model, we show that chemical (both in the river and in the estuary) and in-river (e.g., dams and/or predation) stressors influence host-susceptibility, increasing the mean force of infection (defined as the per capita acquisition rate of infection) by a factor of 2.2 and 1.6, respectively. Using Listonella anguillarum as a model pathogen, nonchemical in-river and chemical stressors contribute equally to a cumulative incidence of delayed disease-induced mortalities in Chinook salmon that range from 3% to 18% for estuary residence times of 30-120 days, respectively. Mitigation of environmental stressors that increase host-susceptibility could represent a significant component in future management strategies to recover listed stocks. PMID:16201666

  14. Dynamically tunable graphene/dielectric photonic crystal transmission lines

    NASA Astrophysics Data System (ADS)

    Williamson, Ian; Mousavi, S. Hossein; Wang, Zheng

    2015-03-01

    It is well known that graphene supports plasmonic modes with high field confinement and lower losses when compared to conventional metals. Additionally, graphene features a highly tunable conductivity through which the plasmon dispersion can be modulated. Over the years these qualities have inspired a wide range of applications for graphene in the THz and infrared regimes. In this presentation we theoretically demonstrate a graphene parallel plate waveguide (PPWG) that sandwiches a 2D photonic crystal slab. The marriage of these two geometries offers a large two dimensional band gap that can be dynamically tuned over a very broad bandwidth. Our device operates in the low-THz band where the graphene PPWG supports a quasi-TEM mode with a relatively flat attenuation. Unlike conventional photonic crystal slabs, the quasi-TEM nature of the graphene PPWG mode allows the slab thickness to be less than 1/10 of the photonic crystal lattice constant. These features offer up a wealth of opportunities, including tunable metamaterials with a possible platform for large band gaps in 3D structures through tiling and stacking. Additionally, the geometry provides a platform for tunable defect cavities without needing three dimensional periodicity.

  15. Maternal antibodies contribute to sex-based difference in hantavirus transmission dynamics

    PubMed Central

    Kallio, Eva R.; Henttonen, Heikki; Koskela, Esa; Lundkvist, Åke; Mappes, Tapio; Vapalahti, Olli

    2013-01-01

    Individuals often differ in their ability to transmit disease and identifying key individuals for transmission is a major issue in epidemiology. Male hosts are often thought to be more important than females for parasite transmission and persistence. However, the role of infectious females, particularly the transient immunity provided to offspring through maternal antibodies (MatAbs), has been neglected in discussions about sex-biased infection transmission. We examined the effect of host sex upon infection dynamics of zoonotic Puumala hantavirus (PUUV) in semi-natural, experimental populations of bank vole (Myodes glareolus). Populations were founded with either females or males that were infected with PUUV, whereas the other sex was immunized against PUUV infection. The likelihood of the next generation being infected was lower when the infected founders were females, underlying the putative importance of adult males in PUUV transmission and persistence in host populations. However, we show that this effect probably results from transient immunity that infected females provide to their offspring, rather than any sex-biased transmission efficiency per se. Our study proposes a potential contrasting nature of female and male hosts in the transmission dynamics of hantaviruses. PMID:24352416

  16. DYNAMICS OF SI MODELS WITH BOTH HORIZONTAL AND VERTICAL TRANSMISSIONS AS WELL AS ALLEE EFFECTS*

    PubMed Central

    Kang, Yun; Castillo-Chavez, Carlos

    2014-01-01

    A general SI (Susceptible-Infected) epidemic system of host-parasite interactions operating under Allee effects, horizontal and/or vertical transmission, and where infected individuals experience pathogen-induced reductions in reproductive ability, is introduced. The initial focus of this study is on the analyses of the dynamics of Density-Dependent and Frequency-Dependent effects on SI models (SI-DD and SI-FD). The analyses identify conditions involving horizontal and vertical transmitted reproductive numbers, namely those used to characterize and contrast SI-FD and SI-DD dynamics. Conditions that lead to disease-driven extinction, or disease-free dynamics, or susceptible-free dynamics, or endemic disease patterns are identified. The SI-DD system supports richer dynamics including limit cycles while the SI-FD model only supports equilibrium dynamics. SI models under “small” horizontal transmission rates may result in disease-free dynamics. SI models under with and inefficient reproductive infectious class may lead to disease-driven extinction scenarios. The SI-DD model supports stable periodic solutions that emerge from an unstable equilibrium provided that either the Allee threshold and/or the disease transmission rate is large; or when the disease has limited influence on the infectives growth rate; and/or when disease-induced mortality is low. Host-parasite systems where diffusion or migration of local populations manage to destabilize them are examples of what is known as diffusive instability. The exploration of SI-dynamics in the presence of dispersal brings up the question of whether or not diffusive instability is a possible outcome. Here, we briefly look at such possibility within two-patch coupled SI-DD and SI-FD systems. It is shown that relative high levels of asymmetry, two modes of transmission, frequency dependence, and Allee effects are capable of supporting diffusive instability. PMID:24389426

  17. Transmission and Demographic Dynamics of Coxsackievirus B1.

    PubMed

    Chu, Pei-Yu; Tyan, Yu-Chang; Chen, Yao-Shen; Chen, Hsiu-Lin; Lu, Po-Liang; Chen, Yu-Hsien; Chen, Bao-Chen; Huang, Tsi-Shu; Wang, Chu-Feng; Su, Hui-Ju; Shi, Yong-Ying; Sanno-Duanda, Bintou; Lin, Kuei-Hsiang; Motomura, Kazushi

    2015-01-01

    The infectious activity of coxsackievirus B1 (CV-B1) in Taiwan was high from 2008 to 2010, following an alarming increase in severe neonate disease in the United States (US). To examine the relationship between CV-B1 strains isolated in Taiwan and those from other parts of the world, we performed a phylodynamic study using VP1 and partial 3Dpol (414 nt) sequences from 22 strains of CV-B1 isolated in Taiwan (1989-2010) and compared them to sequences from strains isolated worldwide. Phylogenetic trees were constructed by neighbor-joining, maximum likelihood, and Bayesian Monte Carlo Markov Chain methods. Four genotypes (GI-IV) in the VP1 region of CV-B1 and three genotypes (GA-C) in the 3Dpol region of enterovirus B were identified and had high support values. The phylogenetic analysis indicates that the GI and GIII strains in VP1 were geographically distributed in Taiwan (1993-1994) and in India (2007-2009). On the other hand, the GII and GIV strains appear to have a wider spatiotemporal distribution and ladder-like topology A stair-like phylogeny was observed in the VP1 region indicating that the phylogeny of the virus may be affected by different selection pressures in the specified regions. Further, most of the GI and GII strains in the VP1 tree were clustered together in GA in the 3D tree, while the GIV strains diverged into GB and GC. Taken together, these data provide important insights into the population dynamics of CV-B1 and indicate that incongruencies in specific gene regions may contribute to spatiotemporal patterns of epidemicity for this virus. PMID:26053872

  18. HTS DC Transmission Line for Megalopolis Grid Development

    NASA Astrophysics Data System (ADS)

    Kopylov, S.; Sytnikov, V.; Bemert, S.; Ivanov, Yu; Krivetskiy, I.; Romashov, M.; Shakaryan, Yu; Keilin, V.; Shikov, A.; Patrikeev, V.; Lobyntsev, V.; Shcherbakov, V.

    2014-05-01

    Using of HTS AC and DC cables in electric power grids allows increasing of the transferred power, losses diminishing, decreasing of exclusion zone areas, the enhancement of the environmental conditions and fire/explosion safety of electric power systems. However, the use of DC superconducting cable lines together with converters brings additional advantages as reduction of losses in cables and suitable lowering of refrigerating plant capacity, as well as the realization of the function of short-circuit currents limitation by means of the appropriate setting of converter equipment. Russian Federal Grid Company and its R&D Center started the construction of the DC HTS power transmission line which includes the cable itself, cryogenic equipment, AC/DC converters, terminals and cable coupling boxes. This line will connect two substations in Saint-Petersburg - 330 kV "Centralnaya" and 220 kV "RP-9". The length of this HTS transmission line will be about 2500 meters. Nowadays are developed all the elements of the line and technologies of the cable manufacturing. Two HTS cable samples, each 30 m length, have been made. This paper describes the results of cables tests.

  19. Critical-angle Transmission Grating Development for AXSIO

    NASA Astrophysics Data System (ADS)

    Bautz, Mark W.; Heilmann, R. K.; Schattenburg, M.; Marshall, H. L.; Huenemoerder, D.; Dewey, D.; Schulz, N. S.; Davis, J. E.

    2013-04-01

    Large area, high resolving power spectroscopy in the soft x-ray band can at present only be achieved with a state-of-the-art diffraction grating spectrometer. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers such as AXSIO promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit. The CAT grating principle has previously been demonstrated with x rays using small wet-etched samples. We report the latest progress in the fabrication and testing of large (32x32 mm2) CAT grating prototypes with an integrated hierarchy of low-obstruction support structures. The gratings are fabricated from silicon-on-insulator wafers using advanced lithography and highly anisotropic dry and wet etching techniques. We present our latest grating fabrication results.

  20. Progress in the development of critical-angle transmission gratings

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Mukherjee, Pran; Schattenburg, Mark L.

    2012-09-01

    Recently developed Critical-Angle Transmission (CAT) grating technology - in combination with x-ray CCD cameras and large collecting-area focusing optics - will enable a new generation of soft x-ray spectrometers with unprecedented resolving power and effective area and with at least an order of magnitude improvement in figures-of-merit for emission and absorption line detection. This technology will be essential to address a number of high-priority questions identified in the Astro2010 Decadal Survey “New Worlds New Horizons” and open the door to a new discovery space. CAT gratings combine the advantages of soft x-ray transmission gratings (low mass, relaxed figure and alignment tolerances, transparent at high energies) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders to increase resolving power). We report on progress in the fabrication of large-area (31× 31 mm2) free-standing gratings with two levels of low-blockage support structures using highly anisotropic deep reactive-ion etching.

  1. Critical-Angle Transmission Grating Development for AXSIO

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, A.; Mukherjee, P.; Schattenburg, M. L.; Bautz, M. W.; Huenemoerder, D.; Davis, J. E.; Dewey, D.; Marshall, H. L.; Schulz, N. S.

    2013-01-01

    Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Since the demise of IXO there are no soft x-ray spectroscopy missions in the pipeline, but several new mission concepts containing CAT grating based spectrometers such as AXSIO promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit. The CAT grating principle has previously been demonstrated with x rays using small wet-etched samples. We report the latest progress in the fabrication and testing of large (32x32 mm^2) CAT grating prototypes with an integrated hierarchy of low-obstruction support structures. The gratings are fabricated from silicon-on-insulator wafers using advanced lithography and highly anisotropic dry and wet etching techniques. We present our latest grating fabrication results.

  2. Revealing Dynamic Processes of Materials in Liquids Using Liquid Cell Transmission Electron Microscopy

    PubMed Central

    Niu, Kai-Yang; Liao, Hong-Gang; Zheng, Haimei

    2012-01-01

    The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted significant interests across the research fields of materials science, physics, chemistry and biology. The key enabling technology is a liquid cell. We fabricate liquid cells with thin viewing windows through a sequential microfabrication process, including silicon nitride membrane deposition, photolithographic patterning, wafer etching, cell bonding, etc. A liquid cell with the dimensions of a regular TEM grid can fit in any standard TEM sample holder. About 100 nanoliters reaction solution is loaded into the reservoirs and about 30 picoliters liquid is drawn into the viewing windows by capillary force. Subsequently, the cell is sealed and loaded into a microscope for in situ imaging. Inside the TEM, the electron beam goes through the thin liquid layer sandwiched between two silicon nitride membranes. Dynamic processes of nanoparticles in liquids, such as nucleation and growth of nanocrystals, diffusion and assembly of nanoparticles, etc., have been imaged in real time with sub-nanometer resolution. We have also applied this method to other research areas, e.g., imaging proteins in water. Liquid cell TEM is poised to play a major role in revealing dynamic processes of materials in their working environments. It may also bring high impact in the study of biological processes in their native environment. PMID:23287885

  3. Barriers to male transmission of mitochondrial DNA in sperm development.

    PubMed

    DeLuca, Steven Z; O'Farrell, Patrick H

    2012-03-13

    Across the eukaryotic phylogeny, offspring usually inherit their mitochondrial genome from only one of two parents: in animals, the female. Although mechanisms that eliminate paternally derived mitochondria from the zygote have been sought, the developmental stage at which paternal transmission of mitochondrial DNA is restricted is unknown in most animals. Here, we show that the mitochondria of mature Drosophila sperm lack DNA, and we uncover two processes that eliminate mitochondrial DNA during spermatogenesis. Visualization of mitochondrial DNA nucleoids revealed their abrupt disappearance from developing spermatids in a process requiring the mitochondrial nuclease, Endonuclease G. In Endonuclease G mutants, persisting nucleoids are swept out of spermatids by a cellular remodeling process that trims and shapes spermatid tails. Our results show that mitochondrial DNA is eliminated during spermatogenesis, thereby removing the capacity of sperm to transmit the mitochondrial genome to the next generation. PMID:22421049

  4. Exploring the possibility of developing a plastic missile dome for near-infrared transmission

    NASA Astrophysics Data System (ADS)

    Leuw, David H.

    1993-08-01

    The possibility was investigated of developing a missile dome from a transparent plastic for near infra-red transmission by which the windows form an integral part of it. The environmental requirements of the dome were severe as it had to stand up to a velocity in excess of 2 Mach at zero altitude without diminishing its transparency and thus, its optical performance. Several promising plastic candidates were investigated in a hot-wind tunnel and their eventual optical degradation was measured. Special coatings against EMI and reflection losses were applied resisting the high temperature and aero-dynamic pressure occurring during flight. Results of these experiments are given.

  5. Correction for dynamic bias error in transmission measurements of void fraction.

    PubMed

    Andersson, P; Sundén, E Andersson; Svärd, S Jacobsson; Sjöstrand, H

    2012-12-01

    Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision. PMID:23278029

  6. Correction for dynamic bias error in transmission measurements of void fraction

    NASA Astrophysics Data System (ADS)

    Andersson, P.; Sundén, E. Andersson; Svärd, S. Jacobsson; Sjöstrand, H.

    2012-12-01

    Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision.

  7. Postsynaptic conversion of silent synapses during LTP affects synaptic gain and transmission dynamics.

    PubMed

    Poncer, J C; Malinow, R

    2001-10-01

    Synaptic transmission relies on both the gain and the dynamics of synapses. Activity-dependent changes in synaptic gain are well-documented at excitatory synapses and may represent a substrate for information storage in the brain. Here we examine the mechanisms of changes in transmission dynamics at excitatory synapses. We show that paired-pulse ratios (PPRs) of AMPAR and NMDAR EPSCs onto dentate gyrus granule cells are often different; this difference is reduced during LTP, reflecting PPR changes of AMPAR but not NMDAR EPSCs. Presynaptic manipulations, however, produce parallel changes in AMPAR and NMDAR EPSCs. LTP at these synapses reflects a reduction in the proportion of silent synapses lacking functional AMPARs. Changes in PPR during LTP therefore reflect the initial difference between PPRs of silent and functional synapses. Functional conversion of silent synapses permits postsynaptic sampling from additional release sites and thereby affects the dynamics and gain of signals conveyed between neurons. PMID:11544481

  8. Manipulation of host-resource dynamics impacts transmission of trophic parasites.

    PubMed

    Luong, Lien T; Grear, Daniel A; Hudson, Peter J

    2014-09-01

    Many complex life cycle parasites rely on predator-prey interactions for transmission, whereby definitive hosts become infected via the consumption of an infected intermediate host. As such, these trophic parasites are embedded in the larger community food web. We postulated that exposure to infection and, hence, parasite transmission are inherently linked to host foraging ecology, and that perturbation of the host-resource dynamic will impact parasite transmission dynamics. We employed a field manipulation experiment in which natural populations of the eastern chipmunk (Tamias striatus) were provisioned with a readily available food resource in clumped or uniform spatial distributions. Using replicated longitudinal capture-mark-recapture techniques, replicated supplemented and unsupplemented control sites were monitored before and after treatment for changes in infection levels with three gastro-intestinal helminth parasites. We predicted that definitive hosts subject to food supplementation would experience lower rates of exposure to infective intermediate hosts, presumably because they shifted their diet away from the intermediate host towards the more readily available resource (sunflower seeds). As predicted, prevalence of infection by the trophically transmitted parasite decreased in response to supplemental food treatment, but no such change in infection prevalence was detected for the two directly transmitted parasites in the system. The fact that food supplementation only had an impact on the transmission of the trophically transmitted parasite, and not the directly transmitted parasites, supports our hypothesis that host foraging ecology directly affects exposure to parasites that rely on the ingestion of intermediate hosts for transmission. We concluded that the relative availability of different food resources has important consequences for the transmission of parasites and, more specifically, parasites that are embedded in the food web. The broader

  9. Modeling and Analyzing the Transmission Dynamics of HBV Epidemic in Xinjiang, China

    PubMed Central

    Zhang, Tailei; Wang, Kai; Zhang, Xueliang

    2015-01-01

    Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV) which affects livers. In this paper, we formulate a hepatitis B model to study the transmission dynamics of hepatitis B in Xinjiang, China. The epidemic model involves an exponential birth rate and vertical transmission. For a better understanding of HBV transmission dynamics, we analyze the dynamic behavior of the model. The modified reproductive number σ is obtained. When σ < 1, the disease-free equilibrium is locally asymptotically stable, when σ > 1, the disease-free equilibrium is unstable and the disease is uniformly persistent. In the simulation, parameters are chosen to fit public data in Xinjiang. The simulation indicates that the cumulated HBV infection number in Xinjiang will attain about 600,000 cases unless there are stronger or more effective control measures by the end of 2017. Sensitive analysis results show that enhancing the vaccination rate for newborns in Xinjiang is very effective to stop the transmission of HBV. Hence, we recommend that all infants in Xinjiang receive the hepatitis B vaccine as soon as possible after birth. PMID:26422614

  10. Resonance, particle dynamics, and particle transmission in the micro-accelerator platform

    SciTech Connect

    McNeur, J.; Hazra, K. S.; Liu, G.; Sozer, E. B.; Travish, G.; Yoder, R. B.

    2012-12-21

    We describe particle dynamics in the Micro-Accelerator Platform (MAP), a slab-symmetric dielectric laser accelerator (DLA), and model the expected performance of recently fabricated MAP structures. The quality of the structure resonances has been characterized optically, and results are compared with simulation. 3D trajectory analysis is used to model acceleration in those same structures 'as built.' Results are applied to ongoing beam transmission and acceleration tests at NLCTA/E-163, in which transmission of 60 MeV injected electrons through the beam channel of the MAP was clearly observed, despite the overfilling of the structure by the beam.

  11. Transmission dynamic modelling of the impact of human papillomavirus vaccination in the United Kingdom.

    PubMed

    Choi, Yoon Hong; Jit, Mark; Gay, Nigel; Cox, Andrew; Garnett, Geoff P; Edmunds, William John

    2010-05-28

    Many countries are considering vaccination against human papillomavirus (HPV). However, the long-term impact of vaccination is difficult to predict due to uncertainty about the prevalence of HPV infection, pattern of sexual partnerships, progression of cervical neoplasias, accuracy of screening as well as the duration of infectiousness and immunity. Dynamic models of human papillomavirus (HPV) transmission were developed to describe the infection spread and development of cervical neoplasia, cervical cancer (squamous cell and adenocarcinoma) and anogenital warts. Using different combinations of assumptions, 9900 scenarios were created. Each scenario was then fitted to epidemiological data and the best-fitting scenarios used to predict the impact of vaccination. Results suggest that vaccinating 12-year-old girls at 80% coverage will result in a 38-82% reduction in cervical cancer incidence and 44-100% reduction in anogenital warts incidence after 60 years of an ongoing vaccination programme if vaccine protection lasts 20 years on average. The marginal benefit of vaccinating boys depends on the degree of protection achieved by vaccinating girls. PMID:19909831

  12. Multi-host transmission dynamics of schistosomiasis and its optimal control.

    PubMed

    Ding, Chunxiao; Qiu, Zhipeng; Zhu, Huaiping

    2015-10-01

    In this paper we formulate a dynamical model to study the transmission dynamics of schistosomiasis in humans and snails. We also incorporate bovines in the model to study their impact on transmission and controlling the spread of Schistosoma japonicum in humans in China. The dynamics of the model is rigorously analyzed by using the theory of dynamical systems. The theoretical results show that the disease free equilibrium is globally asymptotically stable if R0 < 1, and if R0 > 1 the system has only one positive equilibrium. The local stability of the unique positive equilibrium is investigated and sufficient conditions are also provided for the global stability of the positive equilibrium. The optimal control theory are further applied to the model to study the corresponding optimal control problem. Both analytical and numerical results suggest that: (a) the infected bovines play an important role in the spread of schistosomiasis among humans, and killing the infected bovines will be useful to prevent transmission of schistosomiasis among humans; (b) optimal control strategy performs better than the constant controls in reducing the prevalence of the infected human and the cost for implementing optimal control is much less than that for constant controls; and PMID:26280190

  13. Global Dynamics of a Virus Dynamical Model with Cell-to-Cell Transmission and Cure Rate

    PubMed Central

    Zhang, Tongqian; Meng, Xinzhu; Zhang, Tonghua

    2015-01-01

    The cure effect of a virus model with both cell-to-cell transmission and cell-to-virus transmission is studied. By the method of next generation matrix, the basic reproduction number is obtained. The locally asymptotic stability of the virus-free equilibrium and the endemic equilibrium is considered by investigating the characteristic equation of the model. The globally asymptotic stability of the virus-free equilibrium is proved by constructing suitable Lyapunov function, and the sufficient condition for the globally asymptotic stability of the endemic equilibrium is obtained by constructing suitable Lyapunov function and using LaSalle invariance principal. PMID:26504489

  14. Transmission dynamics of Ebola virus disease and intervention effectiveness in Sierra Leone

    PubMed Central

    Fang, Li-Qun; Yang, Yang; Jiang, Jia-Fu; Yao, Hong-Wu; Kargbo, David; Li, Xin-Lou; Jiang, Bao-Gui; Kargbo, Brima; Tong, Yi-Gang; Wang, Ya-Wei; Liu, Kun; Kamara, Abdul; Dafae, Foday; Kanu, Alex; Jiang, Rui-Ruo; Sun, Ye; Sun, Ruo-Xi; Chen, Wan-Jun; Ma, Mai-Juan; Dean, Natalie E.; Thomas, Harold; Longini, Ira M.; Halloran, M. Elizabeth; Cao, Wu-Chun

    2016-01-01

    Sierra Leone is the most severely affected country by an unprecedented outbreak of Ebola virus disease (EVD) in West Africa. Although successfully contained, the transmission dynamics of EVD and the impact of interventions in the country remain unclear. We established a database of confirmed and suspected EVD cases from May 2014 to September 2015 in Sierra Leone and mapped the spatiotemporal distribution of cases at the chiefdom level. A Poisson transmission model revealed that the transmissibility at the chiefdom level, estimated as the average number of secondary infections caused by a patient per week, was reduced by 43% [95% confidence interval (CI): 30%, 52%] after October 2014, when the strategic plan of the United Nations Mission for Emergency Ebola Response was initiated, and by 65% (95% CI: 57%, 71%) after the end of December 2014, when 100% case isolation and safe burials were essentially achieved, both compared with before October 2014. Population density, proximity to Ebola treatment centers, cropland coverage, and atmospheric temperature were associated with EVD transmission. The household secondary attack rate (SAR) was estimated to be 0.059 (95% CI: 0.050, 0.070) for the overall outbreak. The household SAR was reduced by 82%, from 0.093 to 0.017, after the nationwide campaign to achieve 100% case isolation and safe burials had been conducted. This study provides a complete overview of the transmission dynamics of the 2014−2015 EVD outbreak in Sierra Leone at both chiefdom and household levels. The interventions implemented in Sierra Leone seem effective in containing the epidemic, particularly in interrupting household transmission. PMID:27035948

  15. Transmission dynamics of Ebola virus disease and intervention effectiveness in Sierra Leone.

    PubMed

    Fang, Li-Qun; Yang, Yang; Jiang, Jia-Fu; Yao, Hong-Wu; Kargbo, David; Li, Xin-Lou; Jiang, Bao-Gui; Kargbo, Brima; Tong, Yi-Gang; Wang, Ya-Wei; Liu, Kun; Kamara, Abdul; Dafae, Foday; Kanu, Alex; Jiang, Rui-Ruo; Sun, Ye; Sun, Ruo-Xi; Chen, Wan-Jun; Ma, Mai-Juan; Dean, Natalie E; Thomas, Harold; Longini, Ira M; Halloran, M Elizabeth; Cao, Wu-Chun

    2016-04-19

    Sierra Leone is the most severely affected country by an unprecedented outbreak of Ebola virus disease (EVD) in West Africa. Although successfully contained, the transmission dynamics of EVD and the impact of interventions in the country remain unclear. We established a database of confirmed and suspected EVD cases from May 2014 to September 2015 in Sierra Leone and mapped the spatiotemporal distribution of cases at the chiefdom level. A Poisson transmission model revealed that the transmissibility at the chiefdom level, estimated as the average number of secondary infections caused by a patient per week, was reduced by 43% [95% confidence interval (CI): 30%, 52%] after October 2014, when the strategic plan of the United Nations Mission for Emergency Ebola Response was initiated, and by 65% (95% CI: 57%, 71%) after the end of December 2014, when 100% case isolation and safe burials were essentially achieved, both compared with before October 2014. Population density, proximity to Ebola treatment centers, cropland coverage, and atmospheric temperature were associated with EVD transmission. The household secondary attack rate (SAR) was estimated to be 0.059 (95% CI: 0.050, 0.070) for the overall outbreak. The household SAR was reduced by 82%, from 0.093 to 0.017, after the nationwide campaign to achieve 100% case isolation and safe burials had been conducted. This study provides a complete overview of the transmission dynamics of the 2014-2015 EVD outbreak in Sierra Leone at both chiefdom and household levels. The interventions implemented in Sierra Leone seem effective in containing the epidemic, particularly in interrupting household transmission. PMID:27035948

  16. LINKING THE MODEL OF THE DEVELOPMENT OF PD IN GRAPEVINES TO AN UNDERSTANDING OF THE DYNAMICS OF GWSS TRANSMISSION OF X. FASTIDIOSA TO GRAPEVINES AND GRAPVINE GENE EXPRESSION MARKERS OF PD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For several years we have been studying the development of Pierce’s Disease (PD) in grapevines. Our studies have been guided by a model of PD development proposed with our initial application for funding. The Model proposed several steps in disease development following introduction of the PD caus...

  17. Vector-Virus Interactions and Transmission Dynamics of West Nile Virus

    PubMed Central

    Ciota, Alexander T.; Kramer, Laura D.

    2013-01-01

    West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission. PMID:24351794

  18. Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock

    USGS Publications Warehouse

    Kamath, Pauline L.; Foster, Jeffrey T.; Drees, Kevin P.; Luikart, Gordon; Quance, Christine; Anderson, Neil J.; Clarke, P. Ryan; Cole, Eric K.; Drew, Mark L.; Edwards, William H.; Rhyan, Jack C.; Treanor, John J.; Wallen, Rick L.; White, Patrick J.; Robbe-Austerman, Suelee; Cross, Paul C.

    2016-01-01

    Whole-genome sequencing has provided fundamental insights into infectious disease epidemiology, but has rarely been used for examining transmission dynamics of a bacterial pathogen in wildlife. In the Greater Yellowstone Ecosystem (GYE), outbreaks of brucellosis have increased in cattle along with rising seroprevalence in elk. Here we use a genomic approach to examine Brucella abortus evolution, cross-species transmission and spatial spread in the GYE. We find that brucellosis was introduced into wildlife in this region at least five times. The diffusion rate varies among Brucella lineages (B3 to 8 km per year) and over time. We also estimate 12 host transitions from bison to elk, and 5 from elk to bison. Our results support the notion that free-ranging elk are currently a self-sustaining brucellosis reservoir and the source of livestock infections, and that control measures in bison are unlikely to affect the dynamics of unrelated strains circulating in nearby elk populations.

  19. Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock.

    PubMed

    Kamath, Pauline L; Foster, Jeffrey T; Drees, Kevin P; Luikart, Gordon; Quance, Christine; Anderson, Neil J; Clarke, P Ryan; Cole, Eric K; Drew, Mark L; Edwards, William H; Rhyan, Jack C; Treanor, John J; Wallen, Rick L; White, Patrick J; Robbe-Austerman, Suelee; Cross, Paul C

    2016-01-01

    Whole-genome sequencing has provided fundamental insights into infectious disease epidemiology, but has rarely been used for examining transmission dynamics of a bacterial pathogen in wildlife. In the Greater Yellowstone Ecosystem (GYE), outbreaks of brucellosis have increased in cattle along with rising seroprevalence in elk. Here we use a genomic approach to examine Brucella abortus evolution, cross-species transmission and spatial spread in the GYE. We find that brucellosis was introduced into wildlife in this region at least five times. The diffusion rate varies among Brucella lineages (∼3 to 8 km per year) and over time. We also estimate 12 host transitions from bison to elk, and 5 from elk to bison. Our results support the notion that free-ranging elk are currently a self-sustaining brucellosis reservoir and the source of livestock infections, and that control measures in bison are unlikely to affect the dynamics of unrelated strains circulating in nearby elk populations. PMID:27165544

  20. Synaptic and circuit mechanisms promoting broadband transmission of olfactory stimulus dynamics.

    PubMed

    Nagel, Katherine I; Hong, Elizabeth J; Wilson, Rachel I

    2015-01-01

    Sensory stimuli fluctuate on many timescales. However, short-term plasticity causes synapses to act as temporal filters, limiting the range of frequencies that they can transmit. How synapses in vivo might transmit a range of frequencies in spite of short-term plasticity is poorly understood. The first synapse in the Drosophila olfactory system exhibits short-term depression, but can transmit broadband signals. Here we describe two mechanisms that broaden the frequency characteristics of this synapse. First, two distinct excitatory postsynaptic currents transmit signals on different timescales. Second, presynaptic inhibition dynamically updates synaptic properties to promote accurate transmission of signals across a wide range of frequencies. Inhibition is transient, but grows slowly, and simulations reveal that these two features of inhibition promote broadband synaptic transmission. Dynamic inhibition is often thought to restrict the temporal patterns that a neuron responds to, but our results illustrate a different idea: inhibition can expand the bandwidth of neural coding. PMID:25485755

  1. Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock

    PubMed Central

    Kamath, Pauline L.; Foster, Jeffrey T.; Drees, Kevin P.; Luikart, Gordon; Quance, Christine; Anderson, Neil J.; Clarke, P. Ryan; Cole, Eric K.; Drew, Mark L.; Edwards, William H.; Rhyan, Jack C.; Treanor, John J.; Wallen, Rick L.; White, Patrick J.; Robbe-Austerman, Suelee; Cross, Paul C.

    2016-01-01

    Whole-genome sequencing has provided fundamental insights into infectious disease epidemiology, but has rarely been used for examining transmission dynamics of a bacterial pathogen in wildlife. In the Greater Yellowstone Ecosystem (GYE), outbreaks of brucellosis have increased in cattle along with rising seroprevalence in elk. Here we use a genomic approach to examine Brucella abortus evolution, cross-species transmission and spatial spread in the GYE. We find that brucellosis was introduced into wildlife in this region at least five times. The diffusion rate varies among Brucella lineages (∼3 to 8 km per year) and over time. We also estimate 12 host transitions from bison to elk, and 5 from elk to bison. Our results support the notion that free-ranging elk are currently a self-sustaining brucellosis reservoir and the source of livestock infections, and that control measures in bison are unlikely to affect the dynamics of unrelated strains circulating in nearby elk populations. PMID:27165544

  2. Synaptic and circuit mechanisms promoting broadband transmission of olfactory stimulus dynamics

    PubMed Central

    Nagel, Katherine I.; Hong, Elizabeth J.; Wilson, Rachel I.

    2014-01-01

    Sensory stimuli fluctuate on many timescales. However, short-term plasticity causes synapses to act as temporal filters, limiting the range of frequencies they can transmit. How synapses in vivo might transmit a range of frequencies in spite of short-term plasticity is poorly understood. The first synapse in the Drosophila olfactory system exhibits short-term depression, and yet can transmit broadband signals. Here we describe two mechanisms that broaden the frequency characteristics of this synapse. First, two distinct excitatory postsynaptic currents transmit signals on different timescales. Second, presynaptic inhibition dynamically updates synaptic properties to promote accurate transmission of signals across a wide range of frequencies. Inhibition is transient but grows slowly, and simulations show that these two features of inhibition promote broadband synaptic transmission. Dynamic inhibition is often thought to restrict the temporal patterns that a neuron responds to, but our results illustrate a different idea: inhibition can expand the bandwidth of neural coding. PMID:25485755

  3. Dynamics of a split torque helicopter transmission. M.S. Thesis - Cleveland State Univ.

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    1994-01-01

    Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

  4. Simulating Entanglement Dynamics of Singlet-Triplet Qubits Coupled to a Classical Transmission Line Resonator

    NASA Astrophysics Data System (ADS)

    Wolfe, Michael; Kestner, Jason

    Electrons confined in lateral quantum dots are promising candidates for scalable quantum bits. Particularly, singlet-triplet qubits can entangle electrostatically and offer long coherence times due to their weak interactions with the environment. However, fast two-qubit operations are challenging. We examine the dynamics of singlet triplet qubits capacitively coupled to a classical transmission line resonator driven near resonance. We numerically simulate the dynamics of the von Neumann entanglement entropy and investigate parameters of the coupling element that optimizes the operation time for the qubit.

  5. A review of typhoid fever transmission dynamic models and economic evaluations of vaccination.

    PubMed

    Watson, Conall H; Edmunds, W John

    2015-06-19

    Despite a recommendation by the World Health Organization (WHO) that typhoid vaccines be considered for the control of endemic disease and outbreaks, programmatic use remains limited. Transmission models and economic evaluation may be informative in decision making about vaccine programme introductions and their role alongside other control measures. A literature search found few typhoid transmission models or economic evaluations relative to analyses of other infectious diseases of similar or lower health burden. Modelling suggests vaccines alone are unlikely to eliminate endemic disease in the short to medium term without measures to reduce transmission from asymptomatic carriage. The single identified data-fitted transmission model of typhoid vaccination suggests vaccines can reduce disease burden substantially when introduced programmatically but that indirect protection depends on the relative contribution of carriage to transmission in a given setting. This is an important source of epidemiological uncertainty, alongside the extent and nature of natural immunity. Economic evaluations suggest that typhoid vaccination can be cost-saving to health services if incidence is extremely high and cost-effective in other high-incidence situations, when compared to WHO norms. Targeting vaccination to the highest incidence age-groups is likely to improve cost-effectiveness substantially. Economic perspective and vaccine costs substantially affect estimates, with disease incidence, case-fatality rates, and vaccine efficacy over time also important determinants of cost-effectiveness and sources of uncertainty. Static economic models may under-estimate benefits of typhoid vaccination by omitting indirect protection. Typhoid fever transmission models currently require per-setting epidemiological parameterisation to inform their use in economic evaluation, which may limit their generalisability. We found no economic evaluation based on transmission dynamic modelling, and no

  6. A review of typhoid fever transmission dynamic models and economic evaluations of vaccination

    PubMed Central

    Watson, Conall H.; Edmunds, W. John

    2015-01-01

    Despite a recommendation by the World Health Organization (WHO) that typhoid vaccines be considered for the control of endemic disease and outbreaks, programmatic use remains limited. Transmission models and economic evaluation may be informative in decision making about vaccine programme introductions and their role alongside other control measures. A literature search found few typhoid transmission models or economic evaluations relative to analyses of other infectious diseases of similar or lower health burden. Modelling suggests vaccines alone are unlikely to eliminate endemic disease in the short to medium term without measures to reduce transmission from asymptomatic carriage. The single identified data-fitted transmission model of typhoid vaccination suggests vaccines can reduce disease burden substantially when introduced programmatically but that indirect protection depends on the relative contribution of carriage to transmission in a given setting. This is an important source of epidemiological uncertainty, alongside the extent and nature of natural immunity. Economic evaluations suggest that typhoid vaccination can be cost-saving to health services if incidence is extremely high and cost-effective in other high-incidence situations, when compared to WHO norms. Targeting vaccination to the highest incidence age-groups is likely to improve cost-effectiveness substantially. Economic perspective and vaccine costs substantially affect estimates, with disease incidence, case-fatality rates, and vaccine efficacy over time also important determinants of cost-effectiveness and sources of uncertainty. Static economic models may under-estimate benefits of typhoid vaccination by omitting indirect protection. Typhoid fever transmission models currently require per-setting epidemiological parameterisation to inform their use in economic evaluation, which may limit their generalisability. We found no economic evaluation based on transmission dynamic modelling, and no

  7. Effects of gear box vibration and mass imbalance on the dynamics of multistage gear transmission

    NASA Technical Reports Server (NTRS)

    Choy, F. K.; Tu, Y. K.; Zakrajsek, J. J.; Townsend, D. P.

    1991-01-01

    The dynamic behavior of multistage gear transmission system, with the effects of gear-box-induced vibrations and rotor mass-imbalances is analyzed. The model method, using undamped frequencies and planar mode shapes, is used to reduce the degree-of-freedom of the system. The various rotor-bearing stages as well as lateral and torsional vibrations of each individual stage are coupled through localized gear-mesh-tooth interactions. Gear-box vibrations are coupled to the gear stage dynamics through bearing support forces. Transient and steady state dynamics of lateral and torsional vibrations of the geared system are examined in both time and frequency domain. A typical three-staged geared system is used as an example. Effects of mass-imbalance and gear box vibrations on the system dynamic behavior are presented in terms of modal excitation functions for both lateral and torsional vibrations. Operational characteristics and conclusions are drawn from the results presented.

  8. Inducing Herd Immunity against Seasonal Influenza in Long-Term Care Facilities through Employee Vaccination Coverage: A Transmission Dynamics Model

    PubMed Central

    Wendelboe, Aaron M.; Grafe, Carl; McCumber, Micah; Anderson, Michael P.

    2015-01-01

    Introduction. Vaccinating healthcare workers (HCWs) in long-term care facilities (LTCFs) may effectively induce herd immunity and protect residents against influenza-related morbidity and mortality. We used influenza surveillance data from all LTCFs in New Mexico to validate a transmission dynamics model developed to investigate herd immunity induction. Material and Methods. We adjusted a previously published transmission dynamics model and used surveillance data from an active system among 76 LTCFs in New Mexico during 2006-2007 for model validation. We used a deterministic compartmental model with a stochastic component for transmission between residents and HCWs in each facility in order to simulate the random variation expected in such populations. Results. When outbreaks were defined as a dichotomous variable, our model predicted that herd immunity could be induced. When defined as an attack rate, the model demonstrated a curvilinear trend, but insufficiently strong to induce herd immunity. The model was sensitive to changes in the contact parameter β but was robust to changes in the visitor contact probability. Conclusions. These results further elucidate previous studies' findings that herd immunity may not be induced by vaccinating HCWs in LTCFs; however, increased influenza vaccination coverage among HCWs reduces the probability of influenza infection among residents. PMID:26101542

  9. Exploring Migratory Dynamics on HIV Transmission: The Case of Mexicans in New York City and Puebla, Mexico

    PubMed Central

    Guilamo-Ramos, Vincent; McCarthy, Katharine; Muñoz-Laboy, Miguel A.; de Lourdes Rosas López, Maria

    2014-01-01

    Migration and population movement are increasingly viewed as important factors associated with HIV transmission risk. With growing awareness of the potential impact of migration on HIV transmission, several perspectives have emerged that posit differing dynamics of risk. We considered available data on the role of migration on HIV transmission among Mexican migrants in New York City and Puebla, Mexico. Specifically, we examined 3 distinct models of migratory dynamics of HIV transmission—namely, the structural model, the local contextual model, and the interplay model. In doing so, we reframed current public health perspectives on the role of migration on HIV transmission. PMID:24825203

  10. Systematic evaluation of factors controlling Perkinsus marinus transmission dynamics in lower Chesapeake Bay.

    PubMed

    Ragone Calvo, Lisa M; Dungan, Christopher F; Roberson, Bob S; Burreson, Eugene M

    2003-08-15

    The transmission of Perkinsus marinus in eastern oysters Crassostrea virginica in relation to water temperature, host oyster mortality, and water-column abundance of anti-P. marinus antibody-labeled cells was systematically examined for 20 mo at a site in the lower York River, Virginia, USA. Uninfected sentinel oysters were naturally exposed to the parasite at 2 wk intervals throughout the course of the study to determine the periodicity and rates of parasite transmission. The timing and magnitude of disease-associated oyster mortalities in a local P. marinus-infected oyster population were estimated by monitoring a captive subset of the local oyster population. Flow cytometric immunodetection methods were employed to estimate the abundance of P. marinus cells in water samples collected 3 times each week. The acquisition of P. marinus infections by naïve sentinel oysters occurred sporadically at all times of the year; however, the highest incidence of infection occurred during the months of August and September. This window of maximum parasite transmission coincided with the death of infected hosts within the captive local oyster population. Counts of antibody-labeled cells ranged from 10 to 11900 cells l(-1), with the highest abundances in July and August coincident with maximum summer temperatures. A statistically significant relationship between water-column parasite abundance and infection-acquisition rate was not observed; however, highest parasite-transmission rates in both years occurred during periods of elevated water-column abundance of parasite cells. These results support the prevailing model of P. marinus transmission dynamics by which maximum transmission rates are observed during periods of maximum P. marinus-associated host mortality. However, our results also indicate that transmission can occur when host mortality is low or absent, so alternative mortality-independent dissemination mechanisms are likely. The results also suggest that atypically

  11. Trophic ecology, behaviour and host population dynamics in Echinococcus multilocularis transmission.

    PubMed

    Raoul, F; Hegglin, D; Giraudoux, P

    2015-10-30

    The life cycle of the cestode Echinococcus multilocularis primarily involves canids and small mammals (rodents, lagomorphs) as definitive and intermediate hosts, respectively. Several surveys have identified marked temporal and geographical variations at different scales in the parasite's prevalence in both types of hosts, suggesting variations in the biological and ecological factors that control transmission processes. The parasite transmission from intermediate to definitive hosts is determined by the predator-prey relationship, which theoretically depends on prey population dynamics and the complex dietary response of predators to varying densities of prey species and other food items. Parasite eggs are transmitted to intermediate hosts via carnivore faeces, whose distribution in the environment is driven by the defecating behaviour of final hosts. We reviewed field-based studies that address issues related to the trophic ecology and behaviour of definitive hosts, interactions between definitive and intermediate hosts, and E. multilocularis transmission both in wild and domestic animals in rural and urban environments. Two density-dependent mechanisms control the transmission dynamics in definitive hosts: one is based on the variations in the availability of intermediate hosts, and the other is based on the variations in the density of the definitive host and its faeces. Non-linearity and the direct and delayed responses of definitive host contamination in relation to intermediate host population variations were recorded. The dietary response of the red fox was shown to be complex when abundant alternative resources were available (anthropogenic food, multiple intermediate host prey species). Micro-local hotspots of parasite transmission to intermediate hosts in a landscape, as well as areas of higher risk for human contamination in village and urban settings, may be explained by the definitive hosts' activity patterns and defecation behaviour. PMID:26276578

  12. Malaria transmission dynamics at a site in northern Ghana proposed for testing malaria vaccines.

    PubMed

    Appawu, Maxwell; Owusu-Agyei, Seth; Dadzie, Samuel; Asoala, Victor; Anto, Francis; Koram, Kwadwo; Rogers, William; Nkrumah, Francis; Hoffman, Stephen L; Fryauff, David J

    2004-01-01

    We studied the malaria transmission dynamics in Kassena Nankana district (KND), a site in northern Ghana proposed for testing malaria vaccines. Intensive mosquito sampling for 1 year using human landing catches in three micro-ecological sites (irrigated, lowland and rocky highland) yielded 18 228 mosquitoes. Anopheles gambiae s.l. and Anopheles funestus constituted 94.3% of the total collection with 76.8% captured from the irrigated communities. Other species collected but in relatively few numbers were Anopheles pharoensis (5.4%) and Anopheles rufipes (0.3%). Molecular analysis of 728 An. gambiae.s.l. identified Anopheles gambiae s.s. as the most dominant sibling species (97.7%) of the An. gambiae complex from the three ecological sites. Biting rates of the vectors (36.7 bites per man per night) were significantly higher (P<0.05) in the irrigated area than in the non-irrigated lowland (5.2) and rocky highlands (5.9). Plasmodium falciparum sporozoite rates of 7.2% (295/4075) and 7.1% (269/3773) were estimated for An. gambiae s.s. and An. funestus, respectively. Transmission was highly seasonal, and the heaviest transmission occurred from June to October. The intensity of transmission was higher for people in the irrigated communities than the non-irrigated ones. An overall annual entomological inoculation rate (EIR) of 418 infective bites was estimated in KND. There were micro-ecological variations in the EIRs, with values of 228 infective bites in the rocky highlands, 360 in the lowlands and 630 in the irrigated area. Approximately 60% of malaria transmission in KND occurred indoors during the second half of the night, peaking at daybreak between 04.00 and 06.00 hours. Vaccine trials could be conducted in this district, with timing dependent on the seasonal patterns and intensity of transmission taking into consideration the micro-geographical differences and vaccine trial objectives. PMID:14728621

  13. Evolutionary Analysis of Inter-Farm Transmission Dynamics in a Highly Pathogenic Avian Influenza Epidemic

    PubMed Central

    Bataille, Arnaud; van der Meer, Frank; Stegeman, Arjan; Koch, Guus

    2011-01-01

    Phylogenetic studies have largely contributed to better understand the emergence, spread and evolution of highly pathogenic avian influenza during epidemics, but sampling of genetic data has never been detailed enough to allow mapping of the spatiotemporal spread of avian influenza viruses during a single epidemic. Here, we present genetic data of H7N7 viruses produced from 72% of the poultry farms infected during the 2003 epidemic in the Netherlands. We use phylogenetic analyses to unravel the pathways of virus transmission between farms and between infected areas. In addition, we investigated the evolutionary processes shaping viral genetic diversity, and assess how they could have affected our phylogenetic analyses. Our results show that the H7N7 virus was characterized by a high level of genetic diversity driven mainly by a high neutral substitution rate, purifying selection and limited positive selection. We also identified potential reassortment in the three genes that we have tested, but they had only a limited effect on the resolution of the inter-farm transmission network. Clonal sequencing analyses performed on six farm samples showed that at least one farm sample presented very complex virus diversity and was probably at the origin of chronological anomalies in the transmission network. However, most virus sequences could be grouped within clearly defined and chronologically sound clusters of infection and some likely transmission events between farms located 0.8–13 Km apart were identified. In addition, three farms were found as most likely source of virus introduction in distantly located new areas. These long distance transmission events were likely facilitated by human-mediated transport, underlining the need for strict enforcement of biosafety measures during outbreaks. This study shows that in-depth genetic analysis of virus outbreaks at multiple scales can provide critical information on virus transmission dynamics and can be used to increase

  14. Vectors and transmission dynamics for Setaria tundra (Filarioidea; Onchocercidae), a parasite of reindeer in Finland

    PubMed Central

    Laaksonen, Sauli; Solismaa, Milla; Kortet, Raine; Kuusela, Jussi; Oksanen, Antti

    2009-01-01

    Background Recent studies have revealed expansion by an array of Filarioid nematodes' into the northern boreal region of Finland. The vector-borne nematode, Setaria tundra, caused a serious disease outbreak in the Finnish reindeer population in 2003–05. The main aim of this study was to understand the outbreak dynamics and the rapid expansion of S. tundra in the sub arctic. We describe the vectors of S. tundra, and its development in vectors, for the first time. Finally we discuss the results in the context of the host-parasite ecology of S. tundra in Finland Results Development of S. tundra to the infective stage occurs in mosquitoes, (genera Aedes and Anopheles). We consider Aedes spp. the most important vectors. The prevalence of S. tundra naturally infected mosquitoes from Finland varied from 0.5 to 2.5%. The rate of development in mosquitoes was temperature-dependent. Infective larvae were present approximately 14 days after a blood meal in mosquitoes maintained at room temperature (mean 21 C), but did not develop in mosquitoes maintained outside for 22 days at a mean temperature of 14.1 C. The third-stage (infective) larvae were elongated (mean length 1411 μm (SD 207), and width 28 μm (SD 2)). The anterior end was blunt, and bore two liplike structures, the posterior end slight tapering with a prominent terminal papilla. Infective larvae were distributed anteriorly in the insect's body, the highest abundance being 70 larvae in one mosquito. A questionnaire survey revealed that the peak activity of Culicidae in the reindeer herding areas of Finland was from the middle of June to the end of July and that warm summer weather was associated with reindeer flocking behaviour on mosquito-rich wetlands. Conclusion In the present work, S. tundra vectors and larval development were identified and described for the first time. Aedes spp. mosquitoes likely serve as the most important and competent vectors for S. tundra in Finland. Warm summers apparently promote

  15. Dynamic Analysis of Spur Gear Transmissions (DANST). PC Version 3.00 User Manual

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Lin, Hsiang Hsi; Delgado, Irebert R.

    1996-01-01

    DANST is a FORTRAN computer program for static and dynamic analysis of spur gear systems. The program can be used for parametric studies to predict the static transmission error, dynamic load, tooth bending stress and other properties of spur gears as they are influenced by operating speed, torque, stiffness, damping, inertia, and tooth profile. DANST performs geometric modeling and dynamic analysis for low- or high-contact-ratio spur gears. DANST can simulate gear systems with contact ratios ranging from one to three. It was designed to be easy to use and it is extensively documented in several previous reports and by comments in the source code. This report describes installing and using a new PC version of DANST, covers input data requirements and presents examples.

  16. Neural field simulator: two-dimensional spatio-temporal dynamics involving finite transmission speed

    PubMed Central

    Nichols, Eric J.; Hutt, Axel

    2015-01-01

    Neural Field models (NFM) play an important role in the understanding of neural population dynamics on a mesoscopic spatial and temporal scale. Their numerical simulation is an essential element in the analysis of their spatio-temporal dynamics. The simulation tool described in this work considers scalar spatially homogeneous neural fields taking into account a finite axonal transmission speed and synaptic temporal derivatives of first and second order. A text-based interface offers complete control of field parameters and several approaches are used to accelerate simulations. A graphical output utilizes video hardware acceleration to display running output with reduced computational hindrance compared to simulators that are exclusively software-based. Diverse applications of the tool demonstrate breather oscillations, static and dynamic Turing patterns and activity spreading with finite propagation speed. The simulator is open source to allow tailoring of code and this is presented with an extension use case. PMID:26539105

  17. Complex Dynamics of the Power Transmission Grid (and other Critical Infrastructures)

    NASA Astrophysics Data System (ADS)

    Newman, David

    2015-03-01

    Our modern societies depend crucially on a web of complex critical infrastructures such as power transmission networks, communication systems, transportation networks and many others. These infrastructure systems display a great number of the characteristic properties of complex systems. Important among these characteristics, they exhibit infrequent large cascading failures that often obey a power law distribution in their probability versus size. This power law behavior suggests that conventional risk analysis does not apply to these systems. It is thought that much of this behavior comes from the dynamical evolution of the system as it ages, is repaired, upgraded, and as the operational rules evolve with human decision making playing an important role in the dynamics. In this talk, infrastructure systems as complex dynamical systems will be introduced and some of their properties explored. The majority of the talk will then be focused on the electric power transmission grid though many of the results can be easily applied to other infrastructures. General properties of the grid will be discussed and results from a dynamical complex systems power transmission model will be compared with real world data. Then we will look at a variety of uses of this type of model. As examples, we will discuss the impact of size and network homogeneity on the grid robustness, the change in risk of failure as generation mix (more distributed vs centralized for example) changes, as well as the effect of operational changes such as the changing the operational risk aversion or grid upgrade strategies. One of the important outcomes from this work is the realization that ``improvements'' in the system components and operational efficiency do not always improve the system robustness, and can in fact greatly increase the risk, when measured as a risk of large failure.

  18. System-level performance of LTE-Advanced with joint transmission and dynamic point selection schemes

    NASA Astrophysics Data System (ADS)

    Määttänen, Helka-Liina; Hämäläinen, Kari; Venäläinen, Juha; Schober, Karol; Enescu, Mihai; Valkama, Mikko

    2012-12-01

    In this article, we present a practical coordinated multipoint (CoMP) system for LTE-Advanced. In this CoMP system, cooperation is enabled for cell-edge users via dynamic switching between the normal single-cell operation and CoMP. We first formulate a general CoMP system model of several CoMP schemes. We then investigate a practical finite-rate feedback design that simultaneously supports interference coordination, joint transmission (JT), and dynamic point selection (DPS) with a varying number of cooperating transmission points while operating a single-cell transmission as a fallback mode. We provide both link-level and system-level results for the evaluation of different feedback options for general CoMP operation. The results show that there are substantial performance gains in cell-edge throughputs for both JT and DPS CoMP over the baseline Release 10 LTE-Advanced with practical feedback options. We also show that CoMP can enable improved mobility management in real networks.

  19. Spatial epidemiology of human schistosomiasis in Africa: risk models, transmission dynamics and control☆

    PubMed Central

    Brooker, Simon

    2007-01-01

    Summary This paper reviews recent studies on the spatial epidemiology of human schistosomiasis in Africa. The integrated use of geographical information systems, remote sensing and geostatistics has provided new insights into the ecology and epidemiology of schistosomiasis at a variety of spatial scales. Because large-scale patterns of transmission are influenced by climatic conditions, an increasing number of studies have used remotely sensed environmental data to predict spatial distributions, most recently using Bayesian methods of inference. Such data-driven approaches allow for a more rational implementation of intervention strategies across the continent. It is suggested that improved incorporation of transmission dynamics into spatial models and assessment of uncertainties inherent in data and modelling approaches represent important future research directions. PMID:17055547

  20. Dynamical transmission model of MERS-CoV in two areas

    NASA Astrophysics Data System (ADS)

    Yong, Benny; Owen, Livia

    2016-02-01

    Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a disease first reported in Saudi Arabia in 2012 and it can be transmitted from human to human. This disease has spread to several other countries, most confirmed cases have displayed symptoms of severe acute respiratory illness and many of these patients have died. This research is aimed to construct a mathematical model for the transmission of MERS-CoV in two areas by separating the human population into two groups; susceptible and infectious groups. The dynamics of the disease is studied by a compartmental model involving ordinary differrential equations. The basic reproductive number of this disease is discussed to control the outbreak of this disease. Sensitivity analysis of this model is performed to determine the relative importance of the model parameters to the MERS-CoV transmission.

  1. On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Miller, Eric L.; Dudenhoefer, James E.

    1989-01-01

    The signal distortion inherent to pressure transmission lines in free-piston Stirling engine research is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving the helium-charged free-piston Stirling engines. The underdamped flow regime is described, the primary resonance frequency is derived, and the pressure phase and amplitude distortion are discussed. The scope and limitation of the dynamic response analysis are considered.

  2. On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Miller, Eric L.; Dudenhoefer, James E.

    1989-01-01

    In free piston Stirling engine research the integrity of both amplitude and phase of the dynamic pressure measurements is critical to the characterization of cycle dynamics and thermodynamics. It is therefore necessary to appreciate all possible sources of signal distortion when designing pressure measurement systems for this type of research. The signal distortion inherent to pressure transmission lines is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving helium-charged free piston Stirling engines. The scope and limitations of the dynamic response analysis are considered.

  3. Dynamics of a qubit in a high-impedance transmission line from a bath perspective

    NASA Astrophysics Data System (ADS)

    Bera, Soumya; Baranger, Harold U.; Florens, Serge

    2016-03-01

    We investigate the quantum dynamics of a generic model of light-matter interaction in the context of high-impedance waveguides, focusing on the behavior of the photonic states generated in the waveguide. The model treated consists simply of a two-level system coupled to a bosonic bath (the Ohmic spin-boson model). Quantum quenches as well as scattering of an incident coherent pulse are studied using two complementary methods. First, we develop an approximate ansatz for the electromagnetic waves based on a single multimode coherent state wave function; formally, this approach combines in a single framework ideas from adiabatic renormalization, the Born-Markov approximation, and input-output theory. Second, we present numerically exact results for scattering of a weak intensity pulse by using numerical renormalization group (NRG) calculations. NRG provides a benchmark for any linear response property throughout the ultrastrong-coupling regime. We find that in a sudden quantum quench, the coherent state approach produces physical artifacts, such as improper relaxation to the steady state. These previously unnoticed problems are related to the simplified form of the ansatz that generates spurious correlations within the bath. In the scattering problem, NRG is used to find the transmission and reflection of a single photon, as well as the inelastic scattering of that single photon. Simple analytical formulas are established and tested against the NRG data that predict quantitatively the transport coefficients for up to moderate environmental impedance. These formulas resolve pending issues regarding the presence of inelastic losses in the spin-boson model near absorption resonances, and could be used for comparison to experiments in Josephson waveguide quantum electrodynamics. Finally, the scattering results using the coherent state wave-function approach are compared favorably to the NRG results for very weak incident intensity. We end our study by presenting results

  4. Study on the dynamics responses of a transmission system made from carbon nanotubes

    SciTech Connect

    Yin, Hang; Cai, Kun Wei, Ning; Qin, Qing-Hua; Shi, Jiao

    2015-06-21

    A rotational transmission system from coaxial carbon nanotubes (CNTs) is investigated using a computational molecular dynamics approach. The system consists of a motor from a single-walled carbon nanotube and a bearing from a double-walled carbon nanotube. The motor has a high fixed rotational frequency and the two ends of the outer tube in the bearing are fixed. The inner tube in the bearing works as a rotor. Because of the interlayer friction in the bearing, configurations of the joint between the adjacent ends of motor and rotor have significant effects on rotational transmission properties. Four factors are considered in simulation, i.e., the bonding types of atoms (sp{sup 1} and sp{sup 2}) on the ends of motor and rotor, the difference between motor and rotor radii, the rotational speed of motor, and the environmental temperature. It is found that the synchronous transmission happens if the sp{sup 1} atoms on the jointed ends of motor and rotor are bonded each other and become new sp{sup 2} atoms. Therefore, the lower difference between radii of motor and rotor, higher temperature of environment leads to synchronous rotational transmission easily. If the environmental temperature is too low (e.g., <150 K), the end of motor adjacent to rotor is easily under buckling and new sp{sup 2} atoms appear, too. With capped CNTs or higher radii difference between rotor and motor at an appropriate temperature, a stable asynchronous rotation of rotor can be generated, and the rotor's frequency varying linearly with motor's frequency between 230 and 270 GHz. A multi-signal transmission device combined with oscillating and rotational motion is proposed for motor and stator shares a same size in radius.

  5. The dynamic process and microscopic mechanism of extraordinary terahertz transmission through perforated superconducting films.

    PubMed

    Wu, J B; Zhang, X; Jin, B B; Liu, H T; Chen, Y H; Li, Z Y; Zhang, C H; Kang, L; Xu, W W; Chen, J; Wang, H B; Tonouchi, M; Wu, P H

    2015-01-01

    Superconductor is a compelling plasmonic medium at terahertz frequencies owing to its intrinsic low Ohmic loss and good tuning property. However, the microscopic physics of the interaction between terahertz wave and superconducting plasmonic structures is still unknown. In this paper, we conducted experiments of the enhanced terahertz transmission through a series of superconducting NbN subwavelength hole arrays, and employed microscopic hybrid wave model in theoretical analysis of the role of hybrid waves in the enhanced transmission. The theoretical calculation provided a good match of experimental data. In particular, we obtained the following results. When the width of the holes is far below wavelength, the enhanced transmission is mainly caused by localized resonance around individual holes. On the contrary, when the holes are large, hybrid waves scattered by the array of holes dominate the extraordinary transmission. The surface plasmon polaritions are proved to be launched on the surface of superconducting film and the excitation efficiency increases when the temperature approaches critical temperature and the working frequency goes near energy gap frequency. This work will enrich our knowledge on the microscopic physics of extraordinary optical transmission at terahertz frequencies and contribute to developing terahertz plasmonic devices. PMID:26498994

  6. The dynamic process and microscopic mechanism of extraordinary terahertz transmission through perforated superconducting films

    PubMed Central

    Wu, J. B.; Zhang, X.; Jin, B. B.; Liu, H. T.; Chen, Y. H.; Li, Z. Y.; Zhang, C. H.; Kang, L.; Xu, W. W.; Chen, J.; Wang, H. B.; Tonouchi, M.; Wu, P. H.

    2015-01-01

    Superconductor is a compelling plasmonic medium at terahertz frequencies owing to its intrinsic low Ohmic loss and good tuning property. However, the microscopic physics of the interaction between terahertz wave and superconducting plasmonic structures is still unknown. In this paper, we conducted experiments of the enhanced terahertz transmission through a series of superconducting NbN subwavelength hole arrays, and employed microscopic hybrid wave model in theoretical analysis of the role of hybrid waves in the enhanced transmission. The theoretical calculation provided a good match of experimental data. In particular, we obtained the following results. When the width of the holes is far below wavelength, the enhanced transmission is mainly caused by localized resonance around individual holes. On the contrary, when the holes are large, hybrid waves scattered by the array of holes dominate the extraordinary transmission. The surface plasmon polaritions are proved to be launched on the surface of superconducting film and the excitation efficiency increases when the temperature approaches critical temperature and the working frequency goes near energy gap frequency. This work will enrich our knowledge on the microscopic physics of extraordinary optical transmission at terahertz frequencies and contribute to developing terahertz plasmonic devices. PMID:26498994

  7. A Unifying Multibody Dynamics Algorithm Development Workbench

    NASA Technical Reports Server (NTRS)

    Ziegler, John L.

    2005-01-01

    The development of new and efficient algorithms for multibody dynamics has been an important research area. These algorithms are used for modeling, simulation, and control of systems such as spacecraft, robotic systems, automotive applications, the human body, manufacturing operations, and micro-electromechanical systems (MEMS). At JPL's Dynamics and Real Time Simulation (DARTS) Laboratory we have developed software that serves as a computational workbench for these algorithms. This software utilizes the mathematical perspective of the spatial operator algebra, which allows the development of dynamics algorithms and new insights into multibody dynamics.

  8. Recent developments in dynamic testing of materials

    NASA Astrophysics Data System (ADS)

    Gilat, Amos; Seidt, Jeremy D.

    2015-09-01

    New techniques for dynamic characterization of materials that have been developed in the last three years (since the last DYMAT conference in 2012), and results from recent dynamic testing of Inconel 718 are presented. The first development is a dynamic punch test in which three dimensional Digital Image Correlation (DIC) is used to measure the deformation of the rear surface of a specimen as it being penetrated. The second experimental technique that is under development is a dynamic tension experiment in which full-field strain measurement with DIC and full-field temperature measurement are done simultaneously during the test.

  9. Dynamics of Soft Nanomaterials Captured by Transmission Electron Microscopy in Liquid Water

    PubMed Central

    Proetto, Maria T.; Rush, Anthony M.; Chien, Miao-Ping; Baeza, Patricia Abellan; Patterson, Joseph P.; Thompson, Matthew P.; Olson, Norman H.; Moore, Curtis E.; Rheingold, Arnold L.; Andolina, Christopher; Millstone, Jill; Howell, Stephen B.; Browning, Nigel D.; Evans, James E.; Gianneschi, Nathan C.

    2014-01-01

    In this paper we present in situ transmission electron microscopy (TEM) of synthetic polymeric nanoparticles with emphasis on capturing motion in a solvated, aqueous state. The nanoparticles studied were obtained from the direct polymerization of a Pt(II)-containing monomer. The resulting structures provided sufficient contrast for facile imaging in situ. We contend that this technique will quickly become essential in the characterization of analogous systems, especially where dynamics are of interest in the solvated state. We describe the preparation of the synthetic micellar nanoparticles together with their characterization and motion in liquid water with comparison to conventional electron microscopy analyses. PMID:24422495

  10. Transmission dynamics of schistosomiasis in Zimbabwe: A mathematical and GIS Approach

    NASA Astrophysics Data System (ADS)

    Ngarakana-Gwasira, E. T.; Bhunu, C. P.; Masocha, M.; Mashonjowa, E.

    2016-06-01

    Temperature and presence of water bodies are known to influence the transmission dynamics of schistosomiasis. In this work, effects of water bodies (taken in context of rainfall patterns) and temperature from 1950 to 2000 are considered in the model. With the aid of Geographic Information System (GIS), the reproduction number is mapped on the Zimbabwean country. Results of the mapping show high reproduction numbers along the Lowveld and the Zambezi valley catchment area. High reproduction numbers suggest high levels of schistosomiasis. This result suggests more control efforts should be targeted in these areas with high reproduction numbers.

  11. High dynamic range video transmission and display using standard dynamic range technologies

    NASA Astrophysics Data System (ADS)

    Léonce, A.; Hsu, Tao-i.; Wickramanayake, D. S.; Edirisinghe, E. A.

    2012-06-01

    This paper presents a novel system that makes effective use of High Dynamic Range (HDR) image data to improve and maintain the best viewing quality of video broadcast on current mobile display devices. The proposed approach combines bilateral filtering with an adaptive tone mapping method used to enable the enhancement of the perceptual quality of the video frames at the display device. The bilateral filter separates the frame into large-scale and detail layers. The large-scale layer is divided into bright, mid-tone and dark regions, which are each processed by an appropriate tone mapping function. Ambient and backlight sensors at the display device provide information about current illumination conditions, which are used to intelligently and dynamically vary the levels and thresholds of post-processing applied at the decoder, thereby maintaining a constant level of perceived quality.

  12. Dynamical analysis of transmission line cables. Part 3—Nonlinear theory

    NASA Astrophysics Data System (ADS)

    Barbieri, Renato; Barbieri, Nilson; de Souza Júnior, Oswaldo Honorato

    2008-05-01

    In this work the authors use nonlinear mathematical models for simulation of the dynamical behavior of transmission lines cables. The numerical models are obtained through the finite element method. For validation of the mathematical nonlinear models, the simulated results are compared with experimental data obtained in an automated testing system for overhead line cables. Many sample lengths and load situations were used. The forced response is obtained through an impulsive excitation (impact hammer) or electromechanical shaker and, the vibration signals are collected through accelerometers placed along the half sample. The eigenbehavior is analyzed using the Irvine parameter for straight and inclinated cables. It also showed the numeric and experimental dynamical behavior results for the load cable fluctuation in function of the excitation frequency, the influence of concentrated mass of straight cable and the beat condition.

  13. Transmission dynamics and economics of rabies control in dogs and humans in an African city

    PubMed Central

    Zinsstag, J.; Dürr, S.; Penny, M. A.; Mindekem, R.; Roth, F.; Gonzalez, S. Menendez; Naissengar, S.; Hattendorf, J.

    2009-01-01

    Human rabies in developing countries can be prevented through interventions directed at dogs. Potential cost-savings for the public health sector of interventions aimed at animal-host reservoirs should be assessed. Available deterministic models of rabies transmission between dogs were extended to include dog-to-human rabies transmission. Model parameters were fitted to routine weekly rabid-dog and exposed-human cases reported in N′Djaména, the capital of Chad. The estimated transmission rates between dogs (βd) were 0.0807 km2/(dogs·week) and between dogs and humans (βdh) 0.0002 km2/(dogs·week). The effective reproductive ratio (Re) at the onset of our observations was estimated at 1.01, indicating low-level endemic stability of rabies transmission. Human rabies incidence depended critically on dog-related transmission parameters. We simulated the effects of mass dog vaccination and the culling of a percentage of the dog population on human rabies incidence. A single parenteral dog rabies-mass vaccination campaign achieving a coverage of least 70% appears to be sufficient to interrupt transmission of rabies to humans for at least 6 years. The cost-effectiveness of mass dog vaccination was compared to postexposure prophylaxis (PEP), which is the current practice in Chad. PEP does not reduce future human exposure. Its cost-effectiveness is estimated at US $46 per disability adjusted life-years averted. Cost-effectiveness for PEP, together with a dog-vaccination campaign, breaks even with cost-effectiveness of PEP alone after almost 5 years. Beyond a time-frame of 7 years, it appears to be more cost-effective to combine parenteral dog-vaccination campaigns with human PEP compared to human PEP alone. PMID:19706492

  14. Transmission dynamics and economics of rabies control in dogs and humans in an African city.

    PubMed

    Zinsstag, J; Dürr, S; Penny, M A; Mindekem, R; Roth, F; Menendez Gonzalez, S; Naissengar, S; Hattendorf, J

    2009-09-01

    Human rabies in developing countries can be prevented through interventions directed at dogs. Potential cost-savings for the public health sector of interventions aimed at animal-host reservoirs should be assessed. Available deterministic models of rabies transmission between dogs were extended to include dog-to-human rabies transmission. Model parameters were fitted to routine weekly rabid-dog and exposed-human cases reported in N'Djaména, the capital of Chad. The estimated transmission rates between dogs (beta(d)) were 0.0807 km2/(dogs x week) and between dogs and humans (beta(dh)) 0.0002 km2/(dogs x week). The effective reproductive ratio (R(e)) at the onset of our observations was estimated at 1.01, indicating low-level endemic stability of rabies transmission. Human rabies incidence depended critically on dog-related transmission parameters. We simulated the effects of mass dog vaccination and the culling of a percentage of the dog population on human rabies incidence. A single parenteral dog rabies-mass vaccination campaign achieving a coverage of least 70% appears to be sufficient to interrupt transmission of rabies to humans for at least 6 years. The cost-effectiveness of mass dog vaccination was compared to postexposure prophylaxis (PEP), which is the current practice in Chad. PEP does not reduce future human exposure. Its cost-effectiveness is estimated at US $46 per disability adjusted life-years averted. Cost-effectiveness for PEP, together with a dog-vaccination campaign, breaks even with cost-effectiveness of PEP alone after almost 5 years. Beyond a time-frame of 7 years, it appears to be more cost-effective to combine parenteral dog-vaccination campaigns with human PEP compared to human PEP alone. PMID:19706492

  15. Cholera Transmission in Ouest Department of Haiti: Dynamic Modeling and the Future of the Epidemic

    PubMed Central

    Kirpich, Alexander; Weppelmann, Thomas A.; Yang, Yang; Ali, Afsar; Morris, J. Glenn; Longini, Ira M.

    2015-01-01

    In the current study, a comprehensive, data driven, mathematical model for cholera transmission in Haiti is presented. Along with the inclusion of short cycle human-to-human transmission and long cycle human-to-environment and environment-to-human transmission, this novel dynamic model incorporates both the reported cholera incidence and remote sensing data from the Ouest Department of Haiti between 2010 to 2014. The model has separate compartments for infectious individuals that include different levels of infectivity to reflect the distribution of symptomatic and asymptomatic cases in the population. The environmental compartment, which serves as a source of exposure to toxigenic V. cholerae, is also modeled separately based on the biology of causative bacterium, the shedding of V. cholerae O1 by humans into the environment, as well as the effects of precipitation and water temperature on the concentration and survival of V. cholerae in aquatic reservoirs. Although the number of reported cholera cases has declined compared to the initial outbreak in 2010, the increase in the number of susceptible population members and the presence of toxigenic V. cholerae in the environment estimated by the model indicate that without further improvements to drinking water and sanitation infrastructures, intermittent cholera outbreaks are likely to continue in Haiti. PMID:26488620

  16. 75 FR 76726 - Transmission Technology Solutions, LLC; Western Grid Development, LLC (Complainants) v...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Transmission Technology Solutions, LLC; Western Grid Development, LLC..., LLC (TTS) and Western Grid Development, LLC (WGD) filed a complaint against California...

  17. Dynamic flexibility of the ATPase p97 is important for its interprotomer motion transmission

    PubMed Central

    Huang, Chengdong; Li, Guangtao; Lennarz, William J.

    2012-01-01

    The hexameric protein p97, a very abundant type II AAA ATPase (ATPase associated with various cellular activities), is involved in a diverse range of cellular functions. During its ATPase cycle p97 functions as an ATP motor, converting the chemical energy released upon hydrolysis of ATP to ADP into mechanical work, which is then directed toward the proteins that serve as substrates. A key question in this process is: How is the nucleotide-induced motion transmitted from the C-terminal ATPase domain (the D2 domain) of p97 to the distant N-terminal substrate-processing domain? We have previously reported the surprising finding that motion transmission between the two ATPase domains (the D2 and D1 domains) is mediated by the D1-D2 linker region of its neighboring protomer. In this study we report efforts to better understand this process. Our findings suggest that the amino acid sequence containing Gly-Gly that is located at the C terminus of the D1-D2 linker functions as a pivoting point that allows the dynamic movement of the D1-D2 linker. Furthermore, we found that locking the D1-D2 linker to the D2 domain by introducing disulfide bonds significantly impaired the motion-transmission process. These results support our previous model for interprotomer motion transmission, and provide more detailed information on how the motion transmission between the two ATPase domains of p97 is relayed by the flexible movement of the D1-D2 linker from its neighboring protomer. PMID:22675116

  18. Comparison of transmission dynamics between Streptococcus uberis and Streptococcus agalactiae intramammary infections.

    PubMed

    Leelahapongsathon, Kansuda; Schukken, Ynte Hein; Pinyopummintr, Tanu; Suriyasathaporn, Witaya

    2016-02-01

    parameter and R0 values were not different between both pathogens; however, the duration of infection for Strep. agalactiae was longer than Strep. uberis. These suggest that Strep. uberis may have a different transmission dynamic compared with Strep. agalactiae. PMID:26686709

  19. Using dynamical barriers to control the transmission of light through slowly varying photonic crystals

    NASA Astrophysics Data System (ADS)

    Henning, A. J.; Fromhold, T. M.; Wilkinson, P. B.

    2011-04-01

    We use semiclassical Hamiltonian optics to investigate the propagation of light rays through two-dimensional photonic crystals when slow spatial modulation of the lattice parameters induces mixed stable-chaotic ray dynamics. This modulation changes both the shape and frequency range of the allowed frequency bands, thereby bending the resulting semiclassical ray trajectories and confining them within particular regions of the crystal. The curved boundaries of these regions, combined with the bending of the orbits themselves, creates a hierarchy of stable and unstable chaotic trajectories in phase space. For certain lattice parameters and electromagnetic wave frequencies, islands of stable orbits act as a dynamical barrier, which separates the chaotic trajectories into two distinct regions of the crystal, thereby preventing the rays propagating through the structure. We show that changing the frequency of the electromagnetic wave strongly affects the distribution of stable and unstable orbits in both real and phase space. This switches the dynamical barriers on and off and thus modulates the transmission of rays through the crystal. We propose microwave analogs of the photonic crystals as a route to the experimental study of the transport effects that we predict.

  20. Population dynamics and intra-litter transmission patterns of Isospora suis in suckling piglets under on-farm conditions.

    PubMed

    Sotiraki, S; Roepstorff, A; Nielsen, J P; Maddox-Hyttel, C; Enøe, C; Boes, J; Murrell, K D; Thamsborg, S M

    2008-03-01

    The aim of this study was to investigate the intra-litter infection dynamics of Isospora suis under natural conditions, and to study any association between parasite transmission and the contamination level of the farrowing pen by applying different interventions in order to reduce the transmission of I. suis infection within the litter. The study was divided in 2 trials including in total 22 litters (254 piglets). The first trial included 4 litters (where standard procedures practiced routinely on the farm piglets were applied) and the piglets were followed coprologically from farrowing until 2 weeks after weaning. The sows of those litters were also examined at various intervals before and after farrowing. The second trial included the application of 3 different management procedures: (A) standard farm hygiene and management procedures, (B) standard farm hygiene and management procedures+the first piglets found to excrete I. suis oocysts in each pen were removed from the pen, and (C) reduced cleaning. Each procedure was studied in 2 litters. This was replicated 3 times to yield a total of 18 litters. The results suggested that (i) the sow does not play an important role in transmission of I. suis in the farrowing pen; (ii) in natural infections, both the age of the piglet age at onset of oocyst excretion and the oocyst excretion patterns may vary considerably; (iii) the course of oocyst excretion or development of diarrhoea is related to the time of initial infection and (iii) piglets, which are heavy at birth, are more prone to acquire I. suis infection. Moreover, it was demonstrated that cleaning could be an effective means of restricting the spread of the parasite within the litter and thus the development of diarrhoea. PMID:18021464

  1. Professional Development Networks: From Transmission to Co-Construction

    ERIC Educational Resources Information Center

    Ngcoza, Ken; Southwood, Sue

    2015-01-01

    This article offers an extract of a qualitative case study focused on collaborative professional development of science teachers in a transformative continuous professional development (TCPD) network, whose aim is the professional development of science teachers with a view to improving praxis. Teacher narratives generated through an iterative…

  2. In Situ Transmission Electron Microscopy And Spectroscopy Studies Of Rechargeable Batteries Under Dynamic Operating Conditions: A Retrospective And Perspective View

    SciTech Connect

    Wang, Chong M.

    2015-02-14

    Since the advent of the transmission electron microscope (TEM), continuing efforts have been made to image material under native and reaction environments that typically involve liquids, gases, and external stimuli. With the advances of aberration-corrected TEM for improving the imaging resolution, steady progress has been made on developing methodologies that allow imaging under dynamic operating conditions, or in situ TEM imaging. The success of in situ TEM imaging is closely associated with advances in microfabrication techniques that enable manipulation of nanoscale objects around the objective lens of the TEM. This paper summarizes and highlights recent progress involving in situ TEM studies of energy storage materials, especially rechargeable batteries. The paper is organized to cover both the in situ TEM techniques and the scientific discoveries made possible by in situ TEM imaging.

  3. Clocking the anisotropic lattice dynamics of multi-walled carbon nanotubes by four-dimensional ultrafast transmission electron microscopy

    PubMed Central

    Cao, Gaolong; Sun, Shuaishuai; Li, Zhongwen; Tian, Huanfang; Yang, Huaixin; Li, Jianqi

    2015-01-01

    Recent advances in the four-dimensional ultrafast transmission electron microscope (4D-UTEM) with combined spatial and temporal resolutions have made it possible to directly visualize structural dynamics of materials at the atomic level. Herein, we report on our development on a 4D-UTEM which can be operated properly on either the photo-emission or the thermionic mode. We demonstrate its ability to obtain sequences of snapshots with high spatial and temporal resolutions in the study of lattice dynamics of the multi-walled carbon nanotubes (MWCNTs). This investigation provides an atomic level description of remarkable anisotropic lattice dynamics at the picosecond timescales. Moreover, our UTEM measurements clearly reveal that distinguishable lattice relaxations appear in intra-tubular sheets on an ultrafast timescale of a few picoseconds and after then an evident lattice expansion along the radial direction. These anisotropic behaviors in the MWCNTs are considered arising from the variety of chemical bonding, i.e. the weak van der Waals bonding between the tubular planes and the strong covalent sp2-hybridized bonds in the tubular sheets. PMID:25672762

  4. Intergenerational Wealth Transmission and the Dynamics of Inequality in Small-Scale Societies*

    PubMed Central

    Mulder, Monique Borgerhoff; Bowles, Samuel; Hertz, Tom; Bell, Adrian; Beise, Jan; Clark, Greg; Fazzio, Ila; Gurven, Michael; Hill, Kim; Hooper, Paul L.; Irons, William; Kaplan, Hillard; Leonetti, Donna; Low, Bobbi; Marlowe, Frank; McElreath, Richard; Naidu, Suresh; Nolin, David; Piraino, Patrizio; Quinlan, Rob; Schniter, Eric; Sear, Rebecca; Shenk, Mary; Smith, Eric Alden; von Rueden, Christopher; Wiessner, Polly

    2009-01-01

    Small-scale human societies range from foraging bands with a strong egalitarian ethos to more economically stratified agrarian and pastoral societies. We explain this variation in inequality using a dynamic model in which a population’s long-run steady-state level of inequality depends on the extent to which its most important forms of wealth are transmitted within families across generations. We estimate the degree of intergenerational transmission of three different types of wealth (material, embodied, and relational) as well as the extent of wealth inequality in 21 historical and contemporary populations. We show that intergenerational transmission of wealth and wealth inequality are substantial among pastoral and small-scale agricultural societies (on a par with or even exceeding the most unequal modern industrial economies) and quite limited among horticultural and foraging peoples (equivalent to the most egalitarian of modern industrial populations). Differences in the technology by which a people derive their livelihood and in the institutions and norms making up the economic system jointly contribute to this pattern. PMID:19900925

  5. Epidemiology, transmission dynamics and control of SARS: the 2002-2003 epidemic.

    PubMed Central

    Anderson, Roy M; Fraser, Christophe; Ghani, Azra C; Donnelly, Christl A; Riley, Steven; Ferguson, Neil M; Leung, Gabriel M; Lam, T H; Hedley, Anthony J

    2004-01-01

    This paper reviews current understanding of the epidemiology, transmission dynamics and control of the aetiological agent of severe acute respiratory syndrome (SARS). We present analyses of data on key parameters and distributions and discuss the processes of data capture, analysis and public health policy formulation during the SARS epidemic are discussed. The low transmissibility of the virus, combined with the onset of peak infectiousness following the onset of clinical symptoms of disease, transpired to make simple public health measures, such as isolating patients and quarantining their contacts, very effective in the control of the SARS epidemic. We conclude that we were lucky this time round, but may not be so with the next epidemic outbreak of a novel aetiological agent. We present analyses that help to further understanding of what intervention measures are likely to work best with infectious agents of defined biological and epidemiological properties. These lessons learnt from the SARS experience are presented in an epidemiological and public health context. PMID:15306395

  6. Transmission Loss Calculation using A and B Loss Coefficients in Dynamic Economic Dispatch Problem

    NASA Astrophysics Data System (ADS)

    Jethmalani, C. H. Ram; Dumpa, Poornima; Simon, Sishaj P.; Sundareswaran, K.

    2016-04-01

    This paper analyzes the performance of A-loss coefficients while evaluating transmission losses in a Dynamic Economic Dispatch (DED) Problem. The performance analysis is carried out by comparing the losses computed using nominal A loss coefficients and nominal B loss coefficients in reference with load flow solution obtained by standard Newton-Raphson (NR) method. Density based clustering method based on connected regions with sufficiently high density (DBSCAN) is employed in identifying the best regions of A and B loss coefficients. Based on the results obtained through cluster analysis, a novel approach in improving the accuracy of network loss calculation is proposed. Here, based on the change in per unit load values between the load intervals, loss coefficients are updated for calculating the transmission losses. The proposed algorithm is tested and validated on IEEE 6 bus system, IEEE 14 bus, system IEEE 30 bus system and IEEE 118 bus system. All simulations are carried out using SCILAB 5.4 (www.scilab.org) which is an open source software.

  7. The impact of media coverage on the transmission dynamics of human influenza

    PubMed Central

    2011-01-01

    Background There is an urgent need to understand how the provision of information influences individual risk perception and how this in turn shapes the evolution of epidemics. Individuals are influenced by information in complex and unpredictable ways. Emerging infectious diseases, such as the recent swine flu epidemic, may be particular hotspots for a media-fueled rush to vaccination; conversely, seasonal diseases may receive little media attention, despite their high mortality rate, due to their perceived lack of newness. Methods We formulate a deterministic transmission and vaccination model to investigate the effects of media coverage on the transmission dynamics of influenza. The population is subdivided into different classes according to their disease status. The compartmental model includes the effect of media coverage on reporting the number of infections as well as the number of individuals successfully vaccinated. Results A threshold parameter (the basic reproductive ratio) is analytically derived and used to discuss the local stability of the disease-free steady state. The impact of costs that can be incurred, which include vaccination, education, implementation and campaigns on media coverage, are also investigated using optimal control theory. A simplified version of the model with pulse vaccination shows that the media can trigger a vaccinating panic if the vaccine is imperfect and simplified messages result in the vaccinated mixing with the infectives without regard to disease risk. Conclusions The effects of media on an outbreak are complex. Simplified understandings of disease epidemiology, propogated through media soundbites, may make the disease significantly worse. PMID:21356134

  8. Dynamical analysis of transmission line cables. Part 1—linear theory

    NASA Astrophysics Data System (ADS)

    Barbieri, Nilson; Júnior, Oswaldo Honorato de Souza; Barbieri, Renato

    2004-05-01

    In this work the results of theoretical and experimental studies in the dynamical behaviour of electric cables of transmission lines are presented. The numerical analyses are obtained using the finite element method. For validation of the mathematical models, the simulated results are compared with experimental data obtained in an automated testing system for overhead line cables. Three sample lengths were used: 13, 30 and 65 m. The forced responses are obtained through an impulsive excitation. The experimental data were acquired using five accelerometers placed along half the sample. The modal parameters were optimised through a gradient search routine, the complex envelope and the single degree-of-freedom method. A reduced damping matrix was fitted by considering the first five free vibration modes.

  9. Dynamics of soft Nanomaterials captured by transmission electron microscopy in liquid water

    SciTech Connect

    Proetto, Maria T.; Rush, Anthony M.; Chien, Miao-Ping; Abellan Baeza, Patricia; Patterson, Joseph P.; Thompson, Matthew P.; Olson, Norman H.; Moore, Curtis E.; Rheingold, Arnold L.; Andolina, Christopher; Millstone, Jill; Howell, Stephen B.; Browning, Nigel D.; Evans, James E.; Gianneschi, Nathan C.

    2014-01-14

    In this paper we present in situ transmission electron microscopy (TEM) of soft, synthetic nanoparticles with a comparative analysis using conventional TEM methods. This comparison is made with the simple aim of describing what is an unprecedented example of in situ imaging by TEM. However, we contend the technique will quickly become essential in the characterization of analogous systems, especially where dynamics are of interest in the solvated state. In this case, particles were studied which were obtained from the direct polymerization of an oxaliplatin analog, designed for an ongoing program in novel chemotherapeutic delivery systems. The resulting nanoparticles provided sufficient contrast for facile imaging in situ, and point toward key design parameters that enable this new characterization approach for organic nanomaterials. We describe the preparation of the synthetic micellar nanoparticles to- gether with their characterization in liquid water.

  10. Transmission Dynamics and Final Epidemic Size of Ebola Virus Disease Outbreaks with Varying Interventions.

    PubMed

    Barbarossa, Maria Vittoria; Dénes, Attila; Kiss, Gábor; Nakata, Yukihiko; Röst, Gergely; Vizi, Zsolt

    2015-01-01

    The 2014 Ebola Virus Disease (EVD) outbreak in West Africa was the largest and longest ever reported since the first identification of this disease. We propose a compartmental model for EVD dynamics, including virus transmission in the community, at hospitals, and at funerals. Using time-dependent parameters, we incorporate the increasing intensity of intervention efforts. Fitting the system to the early phase of the 2014 West Africa Ebola outbreak, we estimate the basic reproduction number as 1.44. We derive a final size relation which allows us to forecast the total number of cases during the outbreak when effective interventions are in place. Our model predictions show that, as long as cases are reported in any country, intervention strategies cannot be dismissed. Since the main driver in the current slowdown of the epidemic is not the depletion of susceptibles, future waves of infection might be possible, if control measures or population behavior are relaxed. PMID:26197242

  11. Transmission Dynamics and Final Epidemic Size of Ebola Virus Disease Outbreaks with Varying Interventions

    PubMed Central

    Barbarossa, Maria Vittoria; Dénes, Attila; Kiss, Gábor; Nakata, Yukihiko; Röst, Gergely; Vizi, Zsolt

    2015-01-01

    The 2014 Ebola Virus Disease (EVD) outbreak in West Africa was the largest and longest ever reported since the first identification of this disease. We propose a compartmental model for EVD dynamics, including virus transmission in the community, at hospitals, and at funerals. Using time-dependent parameters, we incorporate the increasing intensity of intervention efforts. Fitting the system to the early phase of the 2014 West Africa Ebola outbreak, we estimate the basic reproduction number as 1.44. We derive a final size relation which allows us to forecast the total number of cases during the outbreak when effective interventions are in place. Our model predictions show that, as long as cases are reported in any country, intervention strategies cannot be dismissed. Since the main driver in the current slowdown of the epidemic is not the depletion of susceptibles, future waves of infection might be possible, if control measures or population behavior are relaxed. PMID:26197242

  12. A basic dynamic transmission model of Staphylococcus aureus in the US population.

    PubMed

    Hogea, C; van Effelterre, T; Acosta, C J

    2014-03-01

    We present a basic mathematical model of Staphylococcus aureus transmission in the USA based on natural history of infection and nationally representative data. We employed a Susceptible-Colonized-Infected-Recovered-Susceptible compartmental modelling framework with two different phenotypes of S. aureus: methicillin-susceptible (MSSA) and methicillin-resistant (MRSA). The model is dynamic and accounts for the US population growth. For model calibration/validation, we used published 1999-2005 S. aureus infection data in conjunction with the 2001-2004 National Health and Nutrition Examination Survey colonization data. Baseline model projections illustrated how MRSA might continue to expand and gradually replace MSSA over time, in the absence of intervention, if there is strong competition for colonization. The model-based estimate of the basic reproduction number (R0) highlights the need for infection control. We illustrate the potential population-level impact of intervention with a hypothetical S. aureus vaccination component. PMID:23701989

  13. Performance Evaluation of Hybrid SCM/SAC-OCDMA Transmissions System using Dynamic Cyclic Shift Code

    NASA Astrophysics Data System (ADS)

    Abd, Thanaa Hussein; Aljunid, S. A.; Fadhil, Hilal Adnan; Radhi, Ibrahim Fadhil; Saad, N. M.

    2012-12-01

    In this paper, the performance of a hybrid scheme of Subcarrier Multiplexing (SCM) technique in a Spectral Amplitude Coding (SAC) Optical Code Division Multiple Access (CDMA) transmissions system is evaluated. The hybrid system is design using new code family; we call it Dynamic Cyclic Shift (DCS) code. The DCS code design for SAC-OCDMA system to reduce the effect of Multi Access Interference due to it property of low cross-correlation (λC ≤ 1) between code words. In contrast, the SCM scheme shows the ability to increase the data rate of SAC-OCDMA system. Consequently, the hybrid SCM/SAC-OCDMA system could be one promising solution to the high-capacity access network with low cost effective, good flexibility and enhanced security, which makes an attractive candidate for next-generation broadband access network.

  14. Effect of a preventive vaccine on the dynamics of HIV transmission

    NASA Astrophysics Data System (ADS)

    Gumel, A. B.; Moghadas, S. M.; Mickens, R. E.

    2004-12-01

    A deterministic mathematical model for the transmission dynamics of HIV infection in the presence of a preventive vaccine is considered. Although the equilibria of the model could not be expressed in closed form, their existence and threshold conditions for their stability are theoretically investigated. It is shown that the disease-free equilibrium is locally-asymptotically stable if the basic reproductive number R<1 (thus, HIV disease can be eradicated from the community) and unstable if R>1 (leading to the persistence of HIV within the community). A robust, positivity-preserving, non-standard finite-difference method is constructed and used to solve the model equations. In addition to showing that the anti-HIV vaccine coverage level and the vaccine-induced protection are critically important in reducing the threshold quantity R, our study predicts the minimum threshold values of vaccine coverage and efficacy levels needed to eradicate HIV from the community.

  15. Preventing mother-to-child transmission of HIV in Vietnam and Indonesia: diverging care dynamics.

    PubMed

    Hardon, Anita Petra; Oosterhoff, Pauline; Imelda, Johanna D; Anh, Nguyen Thu; Hidayana, Irwan

    2009-09-01

    How do women and frontline health workers engage in preventing mother-to-child HIV transmission (PMTCT) in urban areas of Vietnam and Indonesia, where HIV is highly stigmatized and is associated with injecting drug use and sex work? This qualitative study explores local dynamics of care, using a mix of observations, focus group discussions, and interviews. In Indonesia the study was conducted in a community-based PMTCT program run by an NGO, while in Vietnam the study explored the care dynamics in routine PMTCT services, implemented by district and provincial public health facilities. In both of these PMTCT arrangements (the routine provider initiated approach in Vietnam and a more client-oriented system in Indonesia), pregnant women value the provision of HIV tests in antenatal care (ANC). Concerns are raised, however, by the unhappy few who test positive. These women are unsatisfied with the quality of counselling, and the failure to provide antiretroviral treatments. Acceptability of HIV testing in ANC is high, but the key policy issue from the perspective of pregnant women is whether the PMTCT services can provide good quality counselling and the necessary follow-up care. We find local level providers of PMTCT are pleased with the PMTCT program. In Vietnam, the PMTCT program offers health workers protection against HIV, since they can refer women away from the district health service for delivery. In Indonesia, community cadres are pleased with the financial incentives gained by mobilizing clients for the program. We conclude that achieving the global aims of reducing HIV infections in children by 50% requires a tailoring of globally designed public health programs to context-specific gendered transmission pathways of HIV, as well as local opportunities for follow-up care and social support. PMID:19576671

  16. Horizontal transmission dynamics of White spot syndrome virus by cohabitation trials in juvenile Penaeus monodon and P. vannamei.

    PubMed

    Tuyen, N X; Verreth, J; Vlak, J M; de Jong, M C M

    2014-11-01

    White spot syndrome virus (WSSV), a rod-shaped double-stranded DNA virus, is an infectious agent causing fatal disease in shrimp farming around the globe. Within shrimp populations WSSV is transmitted very fast, however, the modes and dynamics of transmission of this virus are not well understood. In the current study the dynamics of disease transmission of WSSV were investigated in small, closed populations of Penaeus monodon and Penaeus vannamei. Pair cohabitation experiments using PCR as a readout for virus infection were used to estimate transmission parameters for WSSV in these two species. The mortality rate of contact-infected shrimp in P. monodon was higher than the rate in P. vannamei. The transmission rate parameters for WSSV were not different between the two species. The relative contribution of direct and indirect transmission rates of WSSV differed between the two species. For P. vannamei the direct contact transmission rate of WSSV was significantly lower than the indirect environmental transmission rate, but for P. monodon, the opposite was found. The reproduction ratio R0 for WSSV for these two species of shrimp was estimated to be above one: 2.07 (95%CI 1.53, 2.79) for P. monodon and 1.51 (95%CI 1.12, 2.03) for P. vannamei. The difference in R0 between the two species is due to a lower host mortality and hence a longer infectious period of WSSV in P. monodon. PMID:25189688

  17. Comprehensive Modeling and Analysis of Rotorcraft Variable Speed Propulsion System With Coupled Engine/Transmission/Rotor Dynamics

    NASA Technical Reports Server (NTRS)

    DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well

    2013-01-01

    This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean

  18. The role of climate variability and change in the transmission dynamics and geographic distribution of dengue.

    PubMed

    Thai, Khoa T D; Anders, Katherine L

    2011-08-01

    The mounting evidence for anthropogenic changes in global climate raises many pressing questions about the potential effects on biological systems, and in particular the transmission of infectious diseases. Vector-borne diseases, such as dengue, may be particularly sensitive to both periodic fluctuations and sustained changes in global and local climates, because vector biology and viral replication are temperature- and moisture-dependent. This paper reviews the current state of knowledge on the associations between climate variability, climate change and dengue transmission, and the tools being used to quantify these associations. The underlying causes of dengue's recent global expansion are multifactorial and poorly understood, but climatic factors should be considered within the context of the sociodemographic, economic and immunological determinants that have contributed to dengue's spread. These factors may mediate the direct effects of climate on dengue and many may operate at a very local level. Translating theoretical models of dengue transmission based on historical data into predictive models that can inform public health interventions is a critical next step and efforts should be focused on developing and refining models at smaller spatial scales to characterize the relationships between both climatic and non-climatic factors and dengue risk. PMID:21737578

  19. A quantitative framework for a multi-group model of Schistosomiasis japonicum transmission dynamics and control in Sichuan, China.

    PubMed

    Liang, Song; Maszle, Don; Spear, Robert C

    2002-05-01

    A quantitative framework is presented for the site-specific characterization of schistosomiasis transmission with the object of developing local control strategies. Central to the framework is a worm-burden model using ordinary differential equations of disease transmission in risk groups defined by residence and occupation. The model incorporates temperature- and precipitation-dependent seasonality of infectious stages, snail population dynamics, and seasonal patterns of human water contact specific to the local agricultural setting. The model's parameters are separated into two main subsets, those associated with the general biology of the parasite and its life cycle in the human and the snail and those associated with directly measurable features of disease status in the local population or relevant aspects of the local environment. In this regard, the model is structured and parameterized to take maximum advantage of data that can be collected in rural China by conventional methods. For example, it includes a statistical model for egg excretion to the environment by each risk group which is based on local population surveys of the prevalence and intensity of infection. The second element of the framework of analysis relates to the strategy for parameter estimation and calibration to local conditions. We propose a Bayesian approach in which parameter estimates are refined over time by methods employing extensive computer simulations. An early analysis of data collected between 1987 and 1989 in endemic villages near Xichang City in southwestern Sichuan provides encouragement that parametric uncertainty can be reduced to levels adequate to explore effective control strategies. PMID:12020900

  20. The role of residence times in two-patch dengue transmission dynamics and optimal strategies.

    PubMed

    Lee, Sunmi; Castillo-Chavez, Carlos

    2015-06-01

    The reemergence and geographical dispersal of vector-borne diseases challenge global health experts around the world and in particular, dengue poses increasing difficulties in the Americas, due in part to explosive urban and semi-urban growth, increases of within and between region mobility, the absence of a vaccine, and the limited resources available for public health services. In this work, a simple deterministic two-patch model is introduced to assess the impact of dengue transmission dynamics in heterogeneous environments. The two-patch system models the movement (e.g. urban versus rural areas residence times) of individuals between and within patches/environments using residence-time matrices with entries that budget within and between host patch relative residence times, under the assumption that only the human budgets their residence time across regions. Three scenarios are considered: (i) resident hosts in Patch i visit patch j, where i≠j but not the other way around, a scenario referred to as unidirectional motion; (ii) symmetric bi-directional motion; and (iii) asymmetric bi-directional motion. Optimal control theory is used to identify and evaluate patch-specific control measures aimed at reducing dengue prevalence in humans and vectors at a minimal cost. Optimal policies are computed under different residence-matrix configurations mentioned above as well as transmissibility scenarios characterized by the magnitude of the basic reproduction number. Optimal patch-specific polices can ameliorate the impact of epidemic outbreaks substantially when the basic reproduction number is moderate. The final patch-specific epidemic size variation increases as the residence time matrix moves away from the symmetric case (asymmetry). As expected, the patch where individuals spend most of their time or in the patch where transmissibility is higher tend to support larger patch-specific final epidemic sizes. Hence, focusing on intervention that target areas where

  1. Spatial and temporal dynamics of malaria transmission in rural Western Kenya

    PubMed Central

    2012-01-01

    Background Understanding the relationship between Plasmodium falciparum malaria transmission and health outcomes requires accurate estimates of exposure to infectious mosquitoes. However, measures of exposure such as mosquito density and entomological inoculation rate (EIR) are generally aggregated over large areas and time periods, biasing the outcome-exposure relationship. There are few studies examining the extent and drivers of local variation in malaria exposure in endemic areas. Methods We describe the spatio-temporal dynamics of malaria transmission intensity measured by mosquito density and EIR in the KEMRI/CDC health and demographic surveillance system using entomological data collected during 2002–2004. Geostatistical zero inflated binomial and negative binomial models were applied to obtain location specific (house) estimates of sporozoite rates and mosquito densities respectively. Model-based predictions were multiplied to estimate the spatial pattern of annual entomological inoculation rate, a measure of the number of infective bites a person receive per unit of time. The models included environmental and climatic predictors extracted from satellite data, harmonic seasonal trends and parameters describing space-time correlation. Results Anopheles gambiae s.l was the main vector species accounting for 86 % (n = 2309) of the total mosquitoes collected with the remainder being Anopheles funestus. Sixty eight percent (757/1110) of the surveyed houses had no mosquitoes. Distance to water bodies, vegetation and day temperature were strongly associated with mosquito density. Overall annual point estimates of EIR were 6.7, 9.3 and 9.6 infectious bites per annum for 2002, 2003 and 2004 respectively. Monthly mosquito density and EIR varied over the study period peaking in May during the wet season each year. The predicted and observed densities of mosquitoes and EIR showed a strong seasonal and spatial pattern over the study area. Conclusions Spatio

  2. Contrasting Transmission Dynamics of Co-endemic Plasmodium vivax and P. falciparum: Implications for Malaria Control and Elimination

    PubMed Central

    Noviyanti, Rintis; Coutrier, Farah; Utami, Retno A. S.; Trimarsanto, Hidayat; Tirta, Yusrifar K.; Trianty, Leily; Kusuma, Andreas; Sutanto, Inge; Kosasih, Ayleen; Kusriastuti, Rita; Hawley, William A.; Laihad, Ferdinand; Lobo, Neil; Marfurt, Jutta; Clark, Taane G.; Price, Ric N.; Auburn, Sarah

    2015-01-01

    Background Outside of Africa, P. falciparum and P. vivax usually coexist. In such co-endemic regions, successful malaria control programs have a greater impact on reducing falciparum malaria, resulting in P. vivax becoming the predominant species of infection. Adding to the challenges of elimination, the dormant liver stage complicates efforts to monitor the impact of ongoing interventions against P. vivax. We investigated molecular approaches to inform the respective transmission dynamics of P. falciparum and P. vivax and how these could help to prioritize public health interventions. Methodology/ Principal Findings Genotype data generated at 8 and 9 microsatellite loci were analysed in 168 P. falciparum and 166 P. vivax isolates, respectively, from four co-endemic sites in Indonesia (Bangka, Kalimantan, Sumba and West Timor). Measures of diversity, linkage disequilibrium (LD) and population structure were used to gauge the transmission dynamics of each species in each setting. Marked differences were observed in the diversity and population structure of P. vivax versus P. falciparum. In Bangka, Kalimantan and Timor, P. falciparum diversity was low, and LD patterns were consistent with unstable, epidemic transmission, amenable to targeted intervention. In contrast, P. vivax diversity was higher and transmission appeared more stable. Population differentiation was lower in P. vivax versus P. falciparum, suggesting that the hypnozoite reservoir might play an important role in sustaining local transmission and facilitating the spread of P. vivax infections in different endemic settings. P. vivax polyclonality varied with local endemicity, demonstrating potential utility in informing on transmission intensity in this species. Conclusions/ Significance Molecular approaches can provide important information on malaria transmission that is not readily available from traditional epidemiological measures. Elucidation of the transmission dynamics circulating in a given

  3. Practical Considerations for High Spatial and Temporal Resolution Dynamic Transmission Electron Microscopy

    SciTech Connect

    Armstrong, M; Boyden, K; Browning, N D; Campbell, G H; Colvin, J D; DeHope, B; Frank, A M; Gibson, D J; Hartemann, F; Kim, J S; King, W E; LaGrange, T B; Pyke, B J; Reed, B W; Shuttlesworth, R M; Stuart, B C; Torralva, B R

    2006-05-01

    Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5 x 10{sup 7} electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution <10{sup -6} s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these levels of temporal and spatial resolution for the study of dynamic materials processes will also be discussed.

  4. Gas mixing system for imaging of nanomaterials under dynamic environments by environmental transmission electron microscopy

    SciTech Connect

    Akatay, M. Cem; Zvinevich, Yury; Ribeiro, Fabio H. E-mail: estach@bnl.gov; Baumann, Philipp; Stach, Eric A. E-mail: estach@bnl.gov

    2014-03-15

    A gas mixing manifold system that is capable of delivering a stable pressure stream of a desired composition of gases into an environmental transmission electron microscope has been developed. The system is designed to provide a stable imaging environment upon changes of either the composition of the gas mixture or upon switching from one gas to another. The design of the system is described and the response of the pressure inside the microscope, the sample temperature, and sample drift in response to flow and composition changes of the system are reported.

  5. Echinococcus multilocularis infection in the field vole (Microtus agrestis): an ecological model for studies on transmission dynamics.

    PubMed

    Woolsey, Ian David; Bune, Nethe Eva Touborg; Jensen, Per Moestrup; Deplazes, Peter; Kapel, Christian Moliin Outzen

    2015-05-01

    We propose a model involving the oral inoculation of Echinococcus multilocularis eggs in a vole species and examine the infection dynamics in a dose-response experiment. Defined doses, 100 (n = 8), 500 (n = 5) and 1000 (n = 5) of E. multilocularis eggs were used to inoculate Microtus agrestis. Four female C57BL/6j mice were inoculated with 1000 eggs as positive controls. The groups inoculated with 100 and 500 eggs exhibited significantly higher lesion numbers, and relatively smaller lesion size was observed in the 1000 dose group. Undetectable abortive lesions may be responsible for some form of resource limitation early in the infection, resulting in lower lesion counts and size in the 1000 dose group. The C57BL/6j mice exhibited significantly fewer lesions than M. agrestis. The feasibility of measuring corticosterone (which has been shown to downregulate Th1 cytokines) in rodent hair and tumour necrosis factor (TNF) production in spleen cells was demonstrated by a positive correlation between corticosterone levels and higher lesion counts and TNF production in C57BL/6j, respectively. These results suggest that M. agrestis is more prone to a Th2 immune response than C57BL/6j, which is associated with E. multilocularis susceptibility and may explain why the parasite develops more slowly in murine models. This is the first data to suggest that M. agrestis is capable of supporting E. multilocularis transmission and thus may be suited as a model to describe the infection dynamics in an intermediate host that affects transmission under natural conditions. PMID:25663069

  6. The development of a portable, automatic, microwave transmission line test set

    NASA Astrophysics Data System (ADS)

    de La Fuente, Val; Karuschkat, Glenn; Simone, Frederick

    Existing test sets for flightline testing of microwave transmission lines are complex, semiportable systems requiring the piece-part testing of waveguides, antennas, and transmission line components in the aircraft. Moreover, these systems are not fully automated and require a large degree of manual intervention. Therefore, advances in test-set miniaturization and automatic control techniques can now be utilized to develop a fully portable, automatic test set for the flightline functional and diagnostic fault isolation testing of RF avionics and microwave transmission lines. A description is given of the proposed capabilities of such a tester, and the benefits expected to be derived from its use.

  7. Spatiotemporal Dynamics of Scrub Typhus Transmission in Mainland China, 2006-2014

    PubMed Central

    Hu, Wen-Biao; Haque, Ubydul; Weppelmann, Thomas A.; Wang, Yong; Liu, Yun-Xi; Li, Xin-Lou; Sun, Hai-Long; Sun, Yan-Song; Clements, Archie C. A.; Li, Shen-Long; Zhang, Wen-Yi

    2016-01-01

    Background Scrub typhus is endemic in the Asia-Pacific region including China, and the number of reported cases has increased dramatically in the past decade. However, the spatial-temporal dynamics and the potential risk factors in transmission of scrub typhus in mainland China have yet to be characterized. Objective This study aims to explore the spatiotemporal dynamics of reported scrub typhus cases in mainland China between January 2006 and December 2014, to detect the location of high risk spatiotemporal clusters of scrub typhus cases, and identify the potential risk factors affecting the re-emergence of the disease. Method Monthly cases of scrub typhus reported at the county level between 2006 and 2014 were obtained from the Chinese Center for Diseases Control and Prevention. Time-series analyses, spatiotemporal cluster analyses, and spatial scan statistics were used to explore the characteristics of the scrub typhus incidence. To explore the association between scrub typhus incidence and environmental variables panel Poisson regression analysis was conducted. Results During the time period between 2006 and 2014 a total of 54,558 scrub typhus cases were reported in mainland China, which grew exponentially. The majority of cases were reported each year between July and November, with peak incidence during October every year. The spatiotemporal dynamics of scrub typhus varied over the study period with high-risk clusters identified in southwest, southern, and middle-eastern part of China. Scrub typhus incidence was positively correlated with the percentage of shrub and meteorological variables including temperature and precipitation. Conclusions The results of this study demonstrate areas in China that could be targeted with public health interventions to mitigate the growing threat of scrub typhus in the country. PMID:27479297

  8. Jobs and Economic Development from New Transmission and Generation in Wyoming (Fact Sheet)

    SciTech Connect

    Not Available

    2011-05-01

    Wyoming is a significant energy exporter, producing nearly 40% of the nation's coal and 10% of the nation's natural gas. However, opportunities to add new energy exports in the form of power generation are limited by insufficient transmission capacity. This fact sheet summarizes results from a recent analysis conducted by NREL for the Wyoming Infrastructure Authority (WIA) that estimates jobs and economic development activity that could occur in Wyoming should the market support new investments in power generation and transmission in the state.

  9. Jobs and Economic Development from New Transmission and Generation in Wyoming Fact Sheet

    SciTech Connect

    2011-05-10

    Wyoming is a significant energy exporter, producing nearly 40% of the nation's coal and 10% of the nation's natural gas. However, opportunities to add new energy exports in the form of power generation are limited by insufficient transmission capacity. This fact sheet summarizes results from a recent analysis conducted by NREL for the Wyoming Infrastructure Authority that estimates jobs and economic development activity that could occur in Wyoming should the market support new investments in power generation and transmission in the state.

  10. Fundamental Development of Ultrasonic Information Transmission System for Wearable Devices

    NASA Astrophysics Data System (ADS)

    Suzuki, Shin-nosuke; Ishihara, Manabu; Kobayashi, Yukio; Katane, Tamotsu; Saito, Osami; Kobayashi, Kazuto

    2009-07-01

    A wearable device is an electronic device miniaturized to a wearable size with computing and wireless communication functions. In this study, we have applied a communication system using ultrasonic waves to a wearable device. Ultrasonic waves are safe for the human body and do not cause the malfunction of electronic equipment. In addition, communication using ultrasonic waves is effective for preventing “skimming” because ultrasonic waves can transmit through the human body and have a large attenuation in air. Wearable devices can also be used in areas where electromagnetic waves are limited. We have developed an experimental prototype device. The prototype contains a one-chip microcomputer used to verify the size and battery consumption of the wearable device. As a result, the developed prototype realized bidirectional communication with a suitable device size and power consumption. The communication speed corresponds to 250 kbps. This value is equivalent to that of a conventional IC card system using electromagnetic waves. With this proposed system, we can achive various practical applications that can maintain absolute privacy while transmitting information through the human body.

  11. Dynamics of Forest Malaria Transmission in Balaghat District, Madhya Pradesh, India

    PubMed Central

    Singh, Neeru; Chand, Sunil K.; Bharti, Praveen K.; Singh, Mrigendra P.; Chand, Gyan; Mishra, Ashok K.; Shukla, Man M.; Mahulia, Man M.; Sharma, Ravendra K.

    2013-01-01

    Background An epidemiological and entomological study was carried out in Balaghat district, Madhya Pradesh, India to understand the dynamics of forest malaria transmission in a difficult and hard to reach area where indoor residual spray and insecticide treated nets were used for vector control. Methods This community based cross-sectional study was undertaken from January 2010 to December 2012 in Baihar and Birsa Community Health Centres of district Balaghat for screening malaria cases. Entomological surveillance included indoor resting collections, pyrethrum spray catches and light trap catches. Anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite protein. Findings Plasmodium falciparum infection accounted for >80% of all infections. P. vivax 16.5%, P. malariae 0.75% and remaining were mixed infections of P. falciparum, P. vivax and P. malariae. More than, 30% infections were found in infants under 6 months of age. Overall, an increasing trend in malaria positivity was observed from 2010 to 2012 (chi-square for trend  =  663.55; P<0.0001). Twenty five Anopheles culicifacies (sibling species C, D and E) were positive for circumsporozoite protein of P. falciparum (44%) and P. vivax (56%). Additionally, 2 An. fluviatilis, were found positive for P. falciparum and 1 for P. vivax (sibling species S and T). An. fluviatilis sibling species T was found as vector in forest villages for the first time in India. Conclusion These results showed that the study villages are experiencing almost perennial malaria transmission inspite of indoor residual spray and insecticide treated nets. Therefore, there is a need for new indoor residual insecticides which has longer residual life or complete coverage of population with long lasting insecticide treated nets or both indoor residual spray and long lasting bed nets for effective vector control. There is a need to undertake a well designed case control study to evaluate the efficacy of these

  12. Border Malaria Associated with Multidrug Resistance on Thailand-Myanmar and Thailand-Cambodia Borders: Transmission Dynamic, Vulnerability, and Surveillance

    PubMed Central

    Bhumiratana, Adisak; Intarapuk, Apiradee; Sorosjinda-Nunthawarasilp, Prapa; Maneekan, Pannamas; Koyadun, Surachart

    2013-01-01

    This systematic review elaborates the concepts and impacts of border malaria, particularly on the emergence and spread of Plasmodium falciparum and Plasmodium vivax multidrug resistance (MDR) malaria on Thailand-Myanmar and Thailand-Cambodia borders. Border malaria encompasses any complex epidemiological settings of forest-related and forest fringe-related malaria, both regularly occurring in certain transmission areas and manifesting a trend of increased incidence in transmission prone areas along these borders, as the result of interconnections of human settlements and movement activities, cross-border population migrations, ecological changes, vector population dynamics, and multidrug resistance. For regional and global perspectives, this review analyzes and synthesizes the rationales pertaining to transmission dynamics and the vulnerabilities of border malaria that constrain surveillance and control of the world's most MDR falciparum and vivax malaria on these chaotic borders. PMID:23865048

  13. THE ROLE OF REEF FISH IN THE TRANSMISSION DYNAMICS OF BLACK-BAND DISEASE IN THE FLORIDA KEYS

    EPA Science Inventory

    Aeby, Greta S. and Deborah L. Santavy. In press. Role of Reef Fish in the Transmission Dynamics of Black-Band Disease in the Florida Keys (Abstract). To be presented at the 10th International Coral Reef Symposium, 28 June-2 July 2004, Okinawa, Japan. 1 p. (ERL,GB R998).

    T...

  14. Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

    NASA Astrophysics Data System (ADS)

    Tufano, Saverio; Griffin, Michael J.

    2013-01-01

    The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the dynamic characteristics of the seat, and the dynamic characteristics of the person sitting on the seat. However, it is not known whether seat cushions influence the dynamic response of the human body, whether the human body influences the dynamic response of seat cushions, or the relative importance of human body nonlinearity and seat nonlinearity in causing nonlinearity in measures of seat transmissibility. This study was designed to investigate the nonlinearity of the coupled seat and human body systems and to compare the apparent mass of the human body supported on rigid and foam seats. A frequency domain model was used to identify the dynamic parameters of seat foams and investigate their dependence on the subject-sitting weight and hip breadth. With 15 subjects, the force and acceleration at the seat base and acceleration at the subject interface were measured during random vertical vibration excitation (0.25-25 Hz) at each of five vibration magnitudes, (0.25-1.6 ms-2 r.m.s.) with four seating conditions (rigid flat seat and three foam cushions). The measurements are presented in terms of the subject's apparent mass on the rigid and foam seat surfaces, and the transmissibility and dynamic stiffness of each of the foam cushions. Both the human body and the foams showed nonlinear softening behaviour, which resulted in nonlinear cushion transmissibility. The apparent masses of subjects sitting on the rigid seat and on foam cushions were similar, but with an apparent increase in damping when sitting on the foams. The foam dynamic stiffness showed complex correlations with characteristics of the human body, which differed between foams. The nonlinearities in cushion transmissibilities, expressed in terms of changes in resonance frequencies and moduli, were more dependent on human body nonlinearity than on cushion nonlinearity.

  15. Transmission Line Jobs and Economic Development Impact (JEDI) Model User Reference Guide

    SciTech Connect

    Goldberg, M.; Keyser, D.

    2013-10-01

    The Jobs and Economic Development Impact (JEDI) models, developed through the National Renewable Energy Laboratory (NREL), are freely available, user-friendly tools that estimate the potential economic impacts of constructing and operating power generation projects for a range of conventional and renewable energy technologies. The Transmission Line JEDI model can be used to field questions about the economic impacts of transmission lines in a given state, region, or local community. This Transmission Line JEDI User Reference Guide was developed to provide basic instruction on operating the model and understanding the results. This guide also provides information on the model's underlying methodology, as well as the parameters and references used to develop the cost data contained in the model.

  16. Monitoring software development through dynamic variables

    NASA Technical Reports Server (NTRS)

    Doerflinger, Carl W.; Basili, Victor R.

    1983-01-01

    Research conducted by the Software Engineering Laboratory (SEL) on the use of dynamic variables as a tool to monitor software development is described. Project independent measures which may be used in a management tool for monitoring software development are identified. Several FORTRAN projects with similar profiles are examined. The staff was experienced in developing these types of projects. The projects developed serve similar functions. Because these projects are similar some underlying relationships exist that are invariant between projects. These relationships, once well defined, may be used to compare the development of different projects to determine whether they are evolving the same way previous projects in this environment evolved.

  17. Monitoring software development through dynamic variables

    NASA Technical Reports Server (NTRS)

    Doerflinger, C. W.; Basili, V. R.

    1985-01-01

    Research conducted by the Software Engineering Laboratory (SEL) on the use of dynamic variables as a tool to monitor software development is described. Project independent measures which may be used in a management tool for monitoring software development are identified. Several FORTRAN projects with similar profiles are examined. The staff was experienced in developing these types of projects. The projects developed serve similar functions. Because these projects are similar some underlying relationships exist that are invariant between the projects. These relationships, once well defined, may be used to compare the development of different projects to determine whether they are evolving the same way previous projects in this environment evolved.

  18. Monitoring software development through dynamic variables

    NASA Technical Reports Server (NTRS)

    Doerflinger, C. W.; Basili, V. R.

    1983-01-01

    Research conducted by the Software Engineering Laboratory (SEL) on the use of dynamic variables as a tool to monitor software development is described. Project independent measures which may be used in a management tool for monitoring software development are identified. Several FORTRAN projects with similar profiles are examined. The staff was experienced in developing these types of projects. The projects developed serve similar functions. Because these projects are similar some underlying relationships exist that are invariant between the projects. These relationships, once well defined, may be used to compare the development of different projects to determine whether they are evolving the same way previous projects in this environment evolved.

  19. Discrete-event-dynamic-system-based approaches for scheduling transmissions in multihop packet radio networks

    NASA Astrophysics Data System (ADS)

    Cassandras, Christos G.

    In the classic transmission scheduling problem, the nodes of a packed radio network (PRN) broadcast fixed-length packets over a common resource (the channel). Packet transmissions are subject to interference constraints; for example, if a node is transmitting a packet, then all adjacent (neighboring) nodes must refrain from transmission. One then adopts a slotted time model where every slot is allocated to a set of nodes which can simultaneously transmit without conflict. Thus, a node generally belongs to one or more of these sets (called transmission sets). Our approach is based on viewing the transmission scheduling problem as a single server multiclass polling problem with simultaneous resource possession. Here, a class corresponds to a transmission set. The server corresponds to a channel operating with deterministic service times: a service time is equal to one time slot required for transmitting a packet. The scheduling problem is then equivalent to assigning the server (equivalently, each time slot) to a particular transmissions set. The simultaneous resource possession feature arises because the server is assigned to a transmission set, i.e. it can simultaneously provide service to packets from all nodes which belong to that set. The construction of the transmission set is dependent upon the topology and connectivity of the PRN and is equivalent to a graph partitioning problem. For our purposes, we assume M transmission sets have been specified. Finally, we allow for overlapping transmission sets, i.e. a node can belong to two or more difference transmission sets.

  20. Development of Wireless Data Transmission System for the Monitoring in Geological Disposal of Radioactive Waste - 12063

    SciTech Connect

    Suzuki, Kei; Eto, Jiro; Tanabe, Hiromi; Esaki, Taichi; Takamura, Hisashi; Suyama, Yasuhiro

    2012-07-01

    The authors have been developing a wireless data transmission system to monitor the performance of a geological disposal system for radioactive waste. The system's concepts, advantages, and a recent development focused on reducing transmitter size to suit narrow spaces such as bentonite buffers and boreholes. A wireless transmitter with a built-in temperature sensor and a connector for external sensors has been developed, measuring 130 mm in length and 50 mm in diameter. The capability of the transmitter was confirmed by transmission tests on the ground and in a bentonite block. (authors)

  1. Horizontal transmission dynamics of a glycoprotein G deficient candidate vaccine strain of infectious laryngotracheitis virus and the effect of vaccination on transmission of virulent virus.

    PubMed

    Devlin, Joanne M; Hartley, Carol A; Gilkerson, James R; Coppo, Mauricio J C; Vaz, Paola; Noormohammadi, Amir H; Wells, Ben; Rubite, Ambrosio; Dhand, Navneet K; Browning, Glenn F

    2011-08-01

    Infectious laryngotracheitis virus (ILTV) is an alphaherpesvirus that causes acute respiratory disease in chickens worldwide. The virus is horizontally transmitted and causes large outbreaks of disease. Recent studies have shown that a glycoprotein G deficient candidate vaccine strain of ILTV (ΔgG ILTV) is safe and protects birds from disease following challenge with virulent virus. This study examined the transmission dynamics of this candidate vaccine and of ILTV in field and experimental settings. The reproduction ratio (R₀, average number of secondary infectious cases from a typical infectious case) was calculated from the growth rate of disease epidemics in broiler flocks. Assuming a latent period of 2 days and an infectious period of 4 days R₀ was estimated to be 2.43 (95% CI 2.25-2.69). In experimental settings the transmission characteristics of ΔgG ILTV were similar to those of wildtype virus, and importantly ΔgG ILTV remained safe following one in vivo passage and subsequent infection via contact-exposure. There was minimal transmission of wildtype virus in vaccinated birds. The findings from this study further demonstrate the suitability of ΔgG ILTV for use as a live attenuated vaccine. Knowledge of the basic reproduction ratio of ILTV will be valuable for future studies that aim to improve disease control using vaccination programs. PMID:21689710

  2. The integrin expression profile modulates orientation and dynamics of force transmission at cell-matrix adhesions.

    PubMed

    Balcioglu, Hayri E; van Hoorn, Hedde; Donato, Dominique M; Schmidt, Thomas; Danen, Erik H J

    2015-04-01

    Integrin adhesion receptors connect the extracellular matrix (ECM) to the cytoskeleton and serve as bidirectional mechanotransducers. During development, angiogenesis, wound healing and cancer progression, the relative abundance of fibronectin receptors, including integrins α5β1 and αvβ3, changes, thus altering the integrin composition of cell-matrix adhesions. Here, we show that enhanced αvβ3 expression can fully compensate for loss of α5β1 and other β1 integrins to support outside-in and inside-out force transmission. α5β1 and αvβ3 each mediate actin cytoskeletal remodeling in response to stiffening or cyclic stretching of the ECM. Likewise, α5β1 and αvβ3 support cellular traction forces of comparable magnitudes and similarly increase these forces in response to ECM stiffening. However, cells using αvβ3 respond to lower stiffness ranges, reorganize their actin cytoskeleton more substantially in response to stretch, and show more randomly oriented traction forces. Centripetal traction force orientation requires long stress fibers that are formed through the action of Rho kinase (ROCK) and myosin II, and that are supported by α5β1. Thus, altering the relative abundance of fibronectin-binding integrins in cell-matrix adhesions affects the spatiotemporal organization of force transmission. PMID:25663698

  3. Relational Dynamics in Teacher Professional Development

    ERIC Educational Resources Information Center

    Finkelstein, Carla

    2013-01-01

    Teacher professional development (PD) is considered essential to improving student achievement toward high standards. I argue that while current notions of high quality PD foreground cognitive aspects of learning, they undertheorize the influence of relational dynamics in teacher learning interactions. That is, current conceptions of high quality…

  4. The dynamic development of gender variability.

    PubMed

    Fausto-Sterling, Anne

    2012-01-01

    We diagram and discuss theories of gender identity development espoused by the clinical groups represented in this special issue. We contend that theories of origin relate importantly to clinical practice, and argue that the existing clinical theories are under-developed. Therefore, we develop a dynamic systems framework for gender identity development. Specifically, we suggest that critical aspects of presymbolic gender embodiment occur during infancy as part of the synchronous interplay of caregiver-infant dyads. By 18 months, a transition to symbolic representation and the beginning of an internalization of a sense of gender can be detected and consolidation is quite evident by 3 years of age. We conclude by suggesting empirical studies that could expand and test this framework. With the belief that better, more explicit developmental theory can improve clinical practice, we urge that clinicians take a dynamic developmental view of gender identity formation into account. PMID:22455327

  5. Dynamics of modulated waves in a lossy modified Noguchi electrical transmission line

    NASA Astrophysics Data System (ADS)

    Kengne, E.; Lakhssassi, A.; Liu, W. M.

    2015-06-01

    We study analytically the dynamics of modulated waves in a dissipative modified Noguchi nonlinear electrical network. In the continuum limit, we use the reductive perturbation method in the semidiscrete limit to establish that the propagation of modulated waves in the network is governed by a dissipative nonlinear Schrödinger (NLS) equation. Motivated with a solitary wave type of solution to the NLS equation, we use both the direct method and the Weierstrass's elliptic function method to present classes of bright, kink, and dark solitary wavelike solutions to the dissipative NLS equation of the network. Through the exact solitary wavelike solutions to the dissipative NLS equation, we investigate the effects of the dissipative elements of the network on wave propagation. We show that the wave amplitude decreases and its width increases when the dissipative element of the network increases. It has been also found that the dissipative element of the network can be used to manipulate the motion of solitary waves through the network. This work presents a good analytical approach of investigating the propagation of solitary waves through discrete electrical transmission lines and is very important for studying modulational instability.

  6. Progress in understanding water balance, transmission loss, and groundwater recharge dynamics in drylands

    NASA Astrophysics Data System (ADS)

    Larsen, Joshua

    2016-04-01

    Water resources of sufficient quality for human and ecosystem use are by definition limited within dryland environments. A critical determination of surface water resource availability in drylands is the loss of water as flow is transmitted downstream. These losses can occur via infiltration, evaporation, and terminal ponding, and provide the pathways for groundwater recharge. However, improving our understanding of these dynamics is hampered by the lack of monitoring data and high degree of hydrological variability, which in combination impacts our ability to create calibrated models or indeed validate their results. A summary of progress in understanding transmission losses is presented, which highlights the main limitations and pathways forward. In addition, new research using novel analysis of groundwater hydrographs for recharge estimation, storage - discharge analysis for recharge estimation, geochemical tracers, remote sensing for the calibration of flow hydraulic models, and ecohydrology feedbacks will be presented that in combination pave the way for a greater understanding of how the water budget is partitioned in dryland areas and the sensitivity of this partitioning to change.

  7. Dynamics of modulated waves in a lossy modified Noguchi electrical transmission line.

    PubMed

    Kengne, E; Lakhssassi, A; Liu, W M

    2015-06-01

    We study analytically the dynamics of modulated waves in a dissipative modified Noguchi nonlinear electrical network. In the continuum limit, we use the reductive perturbation method in the semidiscrete limit to establish that the propagation of modulated waves in the network is governed by a dissipative nonlinear Schrödinger (NLS) equation. Motivated with a solitary wave type of solution to the NLS equation, we use both the direct method and the Weierstrass's elliptic function method to present classes of bright, kink, and dark solitary wavelike solutions to the dissipative NLS equation of the network. Through the exact solitary wavelike solutions to the dissipative NLS equation, we investigate the effects of the dissipative elements of the network on wave propagation. We show that the wave amplitude decreases and its width increases when the dissipative element of the network increases. It has been also found that the dissipative element of the network can be used to manipulate the motion of solitary waves through the network. This work presents a good analytical approach of investigating the propagation of solitary waves through discrete electrical transmission lines and is very important for studying modulational instability. PMID:26172780

  8. Quantifying seasonal population fluxes driving rubella transmission dynamics using mobile phone data.

    PubMed

    Wesolowski, Amy; Metcalf, C J E; Eagle, Nathan; Kombich, Janeth; Grenfell, Bryan T; Bjørnstad, Ottar N; Lessler, Justin; Tatem, Andrew J; Buckee, Caroline O

    2015-09-01

    Changing patterns of human aggregation are thought to drive annual and multiannual outbreaks of infectious diseases, but the paucity of data about travel behavior and population flux over time has made this idea difficult to test quantitatively. Current measures of human mobility, especially in low-income settings, are often static, relying on approximate travel times, road networks, or cross-sectional surveys. Mobile phone data provide a unique source of information about human travel, but the power of these data to describe epidemiologically relevant changes in population density remains unclear. Here we quantify seasonal travel patterns using mobile phone data from nearly 15 million anonymous subscribers in Kenya. Using a rich data source of rubella incidence, we show that patterns of population travel (fluxes) inferred from mobile phone data are predictive of disease transmission and improve significantly on standard school term time and weather covariates. Further, combining seasonal and spatial data on travel from mobile phone data allows us to characterize seasonal fluctuations in risk across Kenya and produce dynamic importation risk maps for rubella. Mobile phone data therefore offer a valuable previously unidentified source of data for measuring key drivers of seasonal epidemics. PMID:26283349

  9. High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

    PubMed

    Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

    2016-02-01

    We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams. PMID:26750260

  10. Quantifying seasonal population fluxes driving rubella transmission dynamics using mobile phone data

    PubMed Central

    Wesolowski, Amy; Metcalf, C. J. E.; Eagle, Nathan; Kombich, Janeth; Grenfell, Bryan T.; Bjørnstad, Ottar N.; Lessler, Justin; Tatem, Andrew J.; Buckee, Caroline O.

    2015-01-01

    Changing patterns of human aggregation are thought to drive annual and multiannual outbreaks of infectious diseases, but the paucity of data about travel behavior and population flux over time has made this idea difficult to test quantitatively. Current measures of human mobility, especially in low-income settings, are often static, relying on approximate travel times, road networks, or cross-sectional surveys. Mobile phone data provide a unique source of information about human travel, but the power of these data to describe epidemiologically relevant changes in population density remains unclear. Here we quantify seasonal travel patterns using mobile phone data from nearly 15 million anonymous subscribers in Kenya. Using a rich data source of rubella incidence, we show that patterns of population travel (fluxes) inferred from mobile phone data are predictive of disease transmission and improve significantly on standard school term time and weather covariates. Further, combining seasonal and spatial data on travel from mobile phone data allows us to characterize seasonal fluctuations in risk across Kenya and produce dynamic importation risk maps for rubella. Mobile phone data therefore offer a valuable previously unidentified source of data for measuring key drivers of seasonal epidemics. PMID:26283349

  11. Quantifying Transient States in Materials with the Dynamic Transmission Electron Microscope

    SciTech Connect

    Campbell, G; LaGrange, T; Kim, J; Reed, B; Browning, N

    2009-09-21

    The Dynamic Transmission Electron Microscope (DTEM) offers a means of capturing rapid evolution in a specimen through in-situ microscopy experiments by allowing 15 ns electron micrograph exposure times. The rapid exposure time is enabled by creating a burst of electrons at the emitter by ultraviolet pulsed laser illumination. This burst arrives a specified time after a second laser initiates the specimen reaction. The timing of the two Q-switched lasers is controlled by high-speed pulse generators with a timing error much less than the pulse duration. Both diffraction and imaging experiments can be performed, just as in a conventional TEM. The brightness of the emitter and the total current control the spatial and temporal resolutions. We have demonstrated 7 nm spatial resolution in single 15 ns pulsed images. These single-pulse imaging experiments have been used to study martensitic transformations, nucleation and crystallization of an amorphous metal, and rapid chemical reactions. Measurements have been performed on these systems that are possible by no other experimental approaches currently available.

  12. Transmission of severe acute respiratory syndrome in dynamical small-world networks

    NASA Astrophysics Data System (ADS)

    Masuda, Naoki; Konno, Norio; Aihara, Kazuyuki

    2004-03-01

    The outbreak of severe acute respiratory syndrome (SARS) is still threatening the world because of a possible resurgence. In the current situation that effective medical treatments such as antiviral drugs are not discovered yet, dynamical features of the epidemics should be clarified for establishing strategies for tracing, quarantine, isolation, and regulating social behavior of the public at appropriate costs. Here we propose a network model for SARS epidemics and discuss why superspreaders emerged and why SARS spread especially in hospitals, which were key factors of the recent outbreak. We suggest that superspreaders are biologically contagious patients, and they may amplify the spreads by going to potentially contagious places such as hospitals. To avoid mass transmission in hospitals, it may be a good measure to treat suspected cases without hospitalizing them. Finally, we indicate that SARS probably propagates in small-world networks associated with human contacts and that the biological nature of individuals and social group properties are factors more important than the heterogeneous rates of social contacts among individuals. This is in marked contrast with epidemics of sexually transmitted diseases or computer viruses to which scale-free network models often apply.

  13. The impact of a parkinsonian lesion on dynamic striatal dopamine transmission depends on nicotinic receptor activation.

    PubMed

    Jennings, Katie A; Platt, Nicola J; Cragg, Stephanie J

    2015-10-01

    Dopamine function is disturbed in Parkinson's disease (PD), but whether and how release of dopamine from surviving neurons is altered has long been debated. Nicotinic acetylcholine receptors (nAChRs) on dopamine axons powerfully govern dopamine release and could be critical contributing factors. We revisited whether fundamental properties of dopamine transmission are changed in a parkinsonian brain and tested the potentially profound masking effects of nAChRs. Using real-time detection of dopamine in mouse striatum after a partial 6-hydroxydopamine lesion and under nAChR inhibition, we reveal that dopamine signals show diminished sensitivity to presynaptic activity. This effect manifested as diminished contrast between DA release evoked by the lowest versus highest frequencies. This reduced activity-dependence was underpinned by loss of short-term facilitation of dopamine release, consistent with an increase in release probability (Pr). With nAChRs active, the reduced activity-dependence of dopamine release after a parkinsonian lesion was masked. Consequently, moment-by-moment variation in activity of nAChRs may lead to dynamic co-variation in dopamine signal impairments in PD. PMID:26117304

  14. Transmission Dynamics of Resistant Bacteria in a Predator-Prey System

    PubMed Central

    Gao, Xubin; Pan, Qiuhui

    2015-01-01

    This paper discusses the impact on human health caused by the addition of antibiotics in the feed of food animals. We use the established transmission rule of resistant bacteria and combine it with a predator-prey system to determine a differential equations model. The equations have three steady equilibrium points corresponding to three population dynamics states under the influence of resistant bacteria. In order to quantitatively analyze the stability of the equilibrium points, we focused on the basic reproduction numbers. Then, both the local and global stability of the equilibrium points were quantitatively analyzed by using essential mathematical methods. Numerical results are provided to relate our model properties to some interesting biological cases. Finally, we discuss the effect of the two main parameters of the model, the proportion of antibiotics added to feed and the predation rate, and estimate the human health impacts related to the amount of feed antibiotics used. We further propose an approach for the prevention of the large-scale spread of resistant bacteria and illustrate the necessity of controlling the amount of in-feed antibiotics used. PMID:25821510

  15. The impact of a parkinsonian lesion on dynamic striatal dopamine transmission depends on nicotinic receptor activation

    PubMed Central

    Jennings, Katie A.; Platt, Nicola J.; Cragg, Stephanie J.

    2015-01-01

    Dopamine function is disturbed in Parkinson's disease (PD), but whether and how release of dopamine from surviving neurons is altered has long been debated. Nicotinic acetylcholine receptors (nAChRs) on dopamine axons powerfully govern dopamine release and could be critical contributing factors. We revisited whether fundamental properties of dopamine transmission are changed in a parkinsonian brain and tested the potentially profound masking effects of nAChRs. Using real-time detection of dopamine in mouse striatum after a partial 6-hydroxydopamine lesion and under nAChR inhibition, we reveal that dopamine signals show diminished sensitivity to presynaptic activity. This effect manifested as diminished contrast between DA release evoked by the lowest versus highest frequencies. This reduced activity-dependence was underpinned by loss of short-term facilitation of dopamine release, consistent with an increase in release probability (Pr). With nAChRs active, the reduced activity-dependence of dopamine release after a parkinsonian lesion was masked. Consequently, moment-by-moment variation in activity of nAChRs may lead to dynamic co-variation in dopamine signal impairments in PD. PMID:26117304

  16. A Theoretical Model for the Transmission Dynamics of the Buruli Ulcer with Saturated Treatment

    PubMed Central

    Bonyah, Ebenezer; Dontwi, Isaac

    2014-01-01

    The management of the Buruli ulcer (BU) in Africa is often accompanied by limited resources, delays in treatment, and macilent capacity in medical facilities. These challenges limit the number of infected individuals that access medical facilities. While most of the mathematical models with treatment assume a treatment function proportional to the number of infected individuals, in settings with such limitations, this assumption may not be valid. To capture these challenges, a mathematical model of the Buruli ulcer with a saturated treatment function is developed and studied. The model is a coupled system of two submodels for the human population and the environment. We examine the stability of the submodels and carry out numerical simulations. The model analysis is carried out in terms of the reproduction number of the submodel of environmental dynamics. The dynamics of the human population submodel, are found to occur at the steady states of the submodel of environmental dynamics. Sensitivity analysis is carried out on the model parameters and it is observed that the BU epidemic is driven by the dynamics of the environment. The model suggests that more effort should be focused on environmental management. The paper is concluded by discussing the public implications of the results. PMID:25214885

  17. Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling

    SciTech Connect

    Grapes, Michael D.; LaGrange, Thomas; Reed, Bryan W.; Campbell, Geoffrey H.; Friedman, Lawrence H.; LaVan, David A.; Weihs, Timothy P.

    2014-08-15

    Nanocalorimetry is a chip-based thermal analysis technique capable of analyzing endothermic and exothermic reactions at very high heating and cooling rates. Here, we couple a nanocalorimeter with an extremely fast in situ microstructural characterization tool to identify the physical origin of rapid enthalpic signals. More specifically, we describe the development of a system to enable in situ nanocalorimetry experiments in the dynamic transmission electron microscope (DTEM), a time-resolved TEM capable of generating images and electron diffraction patterns with exposure times of 30 ns–500 ns. The full experimental system consists of a modified nanocalorimeter sensor, a custom-built in situ nanocalorimetry holder, a data acquisition system, and the DTEM itself, and is capable of thermodynamic and microstructural characterization of reactions over a range of heating rates (10{sup 2} K/s–10{sup 5} K/s) accessible by conventional (DC) nanocalorimetry. To establish its ability to capture synchronized calorimetric and microstructural data during rapid transformations, this work describes measurements on the melting of an aluminum thin film. We were able to identify the phase transformation in both the nanocalorimetry traces and in electron diffraction patterns taken by the DTEM. Potential applications for the newly developed system are described and future system improvements are discussed.

  18. Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling

    NASA Astrophysics Data System (ADS)

    Grapes, Michael D.; LaGrange, Thomas; Friedman, Lawrence H.; Reed, Bryan W.; Campbell, Geoffrey H.; Weihs, Timothy P.; LaVan, David A.

    2014-08-01

    Nanocalorimetry is a chip-based thermal analysis technique capable of analyzing endothermic and exothermic reactions at very high heating and cooling rates. Here, we couple a nanocalorimeter with an extremely fast in situ microstructural characterization tool to identify the physical origin of rapid enthalpic signals. More specifically, we describe the development of a system to enable in situ nanocalorimetry experiments in the dynamic transmission electron microscope (DTEM), a time-resolved TEM capable of generating images and electron diffraction patterns with exposure times of 30 ns-500 ns. The full experimental system consists of a modified nanocalorimeter sensor, a custom-built in situ nanocalorimetry holder, a data acquisition system, and the DTEM itself, and is capable of thermodynamic and microstructural characterization of reactions over a range of heating rates (102 K/s-105 K/s) accessible by conventional (DC) nanocalorimetry. To establish its ability to capture synchronized calorimetric and microstructural data during rapid transformations, this work describes measurements on the melting of an aluminum thin film. We were able to identify the phase transformation in both the nanocalorimetry traces and in electron diffraction patterns taken by the DTEM. Potential applications for the newly developed system are described and future system improvements are discussed.

  19. Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling.

    PubMed

    Grapes, Michael D; LaGrange, Thomas; Friedman, Lawrence H; Reed, Bryan W; Campbell, Geoffrey H; Weihs, Timothy P; LaVan, David A

    2014-08-01

    Nanocalorimetry is a chip-based thermal analysis technique capable of analyzing endothermic and exothermic reactions at very high heating and cooling rates. Here, we couple a nanocalorimeter with an extremely fast in situ microstructural characterization tool to identify the physical origin of rapid enthalpic signals. More specifically, we describe the development of a system to enable in situ nanocalorimetry experiments in the dynamic transmission electron microscope (DTEM), a time-resolved TEM capable of generating images and electron diffraction patterns with exposure times of 30 ns-500 ns. The full experimental system consists of a modified nanocalorimeter sensor, a custom-built in situ nanocalorimetry holder, a data acquisition system, and the DTEM itself, and is capable of thermodynamic and microstructural characterization of reactions over a range of heating rates (10(2) K/s-10(5) K/s) accessible by conventional (DC) nanocalorimetry. To establish its ability to capture synchronized calorimetric and microstructural data during rapid transformations, this work describes measurements on the melting of an aluminum thin film. We were able to identify the phase transformation in both the nanocalorimetry traces and in electron diffraction patterns taken by the DTEM. Potential applications for the newly developed system are described and future system improvements are discussed. PMID:25173298

  20. Intra-epidemic evolutionary dynamics of a Dengue virus type 1 population reveal mutant spectra that correlate with disease transmission

    PubMed Central

    Hapuarachchi, Hapuarachchige Chanditha; Koo, Carmen; Kek, Relus; Xu, Helen; Lai, Yee Ling; Liu, Lilac; Kok, Suet Yheng; Shi, Yuan; Chuen, Raphael Lee Tze; Lee, Kim-Sung; Maurer-Stroh, Sebastian; Ng, Lee Ching

    2016-01-01

    Dengue virus (DENV) is currently the most prevalent mosquito-borne viral pathogen. DENVs naturally exist as highly heterogeneous populations. Even though the descriptions on DENV diversity are plentiful, only a few studies have narrated the dynamics of intra-epidemic virus diversity at a fine scale. Such accounts are important to decipher the reciprocal relationship between viral evolutionary dynamics and disease transmission that shape dengue epidemiology. In the current study, we present a micro-scale genetic analysis of a monophyletic lineage of DENV-1 genotype III (epidemic lineage) detected from November 2012 to May 2014. The lineage was involved in an unprecedented dengue epidemic in Singapore during 2013–2014. Our findings showed that the epidemic lineage was an ensemble of mutants (variants) originated from an initial mixed viral population. The composition of mutant spectrum was dynamic and positively correlated with case load. The close interaction between viral evolution and transmission intensity indicated that tracking genetic diversity through time is potentially a useful tool to infer DENV transmission dynamics and thereby, to assess the epidemic risk in a disease control perspective. Moreover, such information is salient to understand the viral basis of clinical outcome and immune response variations that is imperative to effective vaccine design. PMID:26940650

  1. Intra-epidemic evolutionary dynamics of a Dengue virus type 1 population reveal mutant spectra that correlate with disease transmission.

    PubMed

    Hapuarachchi, Hapuarachchige Chanditha; Koo, Carmen; Kek, Relus; Xu, Helen; Lai, Yee Ling; Liu, Lilac; Kok, Suet Yheng; Shi, Yuan; Chuen, Raphael Lee Tze; Lee, Kim-Sung; Maurer-Stroh, Sebastian; Ng, Lee Ching

    2016-01-01

    Dengue virus (DENV) is currently the most prevalent mosquito-borne viral pathogen. DENVs naturally exist as highly heterogeneous populations. Even though the descriptions on DENV diversity are plentiful, only a few studies have narrated the dynamics of intra-epidemic virus diversity at a fine scale. Such accounts are important to decipher the reciprocal relationship between viral evolutionary dynamics and disease transmission that shape dengue epidemiology. In the current study, we present a micro-scale genetic analysis of a monophyletic lineage of DENV-1 genotype III (epidemic lineage) detected from November 2012 to May 2014. The lineage was involved in an unprecedented dengue epidemic in Singapore during 2013-2014. Our findings showed that the epidemic lineage was an ensemble of mutants (variants) originated from an initial mixed viral population. The composition of mutant spectrum was dynamic and positively correlated with case load. The close interaction between viral evolution and transmission intensity indicated that tracking genetic diversity through time is potentially a useful tool to infer DENV transmission dynamics and thereby, to assess the epidemic risk in a disease control perspective. Moreover, such information is salient to understand the viral basis of clinical outcome and immune response variations that is imperative to effective vaccine design. PMID:26940650

  2. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    SciTech Connect

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  3. Controlling Complex Systems and Developing Dynamic Technology

    NASA Astrophysics Data System (ADS)

    Avizienis, Audrius Victor

    In complex systems, control and understanding become intertwined. Following Ilya Prigogine, we define complex systems as having control parameters which mediate transitions between distinct modes of dynamical behavior. From this perspective, determining the nature of control parameters and demonstrating the associated dynamical phase transitions are practically equivalent and fundamental to engaging with complexity. In the first part of this work, a control parameter is determined for a non-equilibrium electrochemical system by studying a transition in the morphology of structures produced by an electroless deposition reaction. Specifically, changing the size of copper posts used as the substrate for growing metallic silver structures by the reduction of Ag+ from solution under diffusion-limited reaction conditions causes a dynamical phase transition in the crystal growth process. For Cu posts with edge lengths on the order of one micron, local forces promoting anisotropic growth predominate, and the reaction produces interconnected networks of Ag nanowires. As the post size is increased above 10 microns, the local interfacial growth reaction dynamics couple with the macroscopic diffusion field, leading to spatially propagating instabilities in the electrochemical potential which induce periodic branching during crystal growth, producing dendritic deposits. This result is interesting both as an example of control and understanding in a complex system, and as a useful combination of top-down lithography with bottom-up electrochemical self-assembly. The second part of this work focuses on the technological development of devices fabricated using this non-equilibrium electrochemical process, towards a goal of integrating a complex network as a dynamic functional component in a neuromorphic computing device. Self-assembled networks of silver nanowires were reacted with sulfur to produce interfacial "atomic switches": silver-silver sulfide junctions, which exhibit

  4. Transmission dynamics of rabies virus in Thailand: Implications for disease control

    PubMed Central

    Denduangboripant, Jessada; Wacharapluesadee, Supaporn; Lumlertdacha, Boonlert; Ruankaew, Nipada; Hoonsuwan, Wirongrong; Puanghat , Apirom; Hemachudha, Thiravat

    2005-01-01

    Background In Thailand, rabies remains a neglected disease with authorities continuing to rely on human death statistics while ignoring the financial burden resulting from an enormous increase in post-exposure prophylaxis. Past attempts to conduct a mass dog vaccination and sterilization program have been limited to Bangkok city and have not been successful. We have used molecular epidemiology to define geographic localization of rabies virus phylogroups and their pattern of spread in Thailand. Methods We analyzed 239 nucleoprotein gene sequences from animal and human brain samples collected from all over Thailand between 1998 and 2002. We then reconstructed a phylogenetic tree correlating these data with geographical information. Results All sequences formed a monophyletic tree of 2 distinct phylogroups, TH1 and TH2. Three subgroups were identified in the TH1 subgroup and were distributed in the middle region of the country. Eight subgroups of TH2 viruses were identified widely distributed throughout the country overlapping the TH1 territory. There was a correlation between human-dependent transportation routes and the distribution of virus. Conclusion Inter-regional migration paths of the viruses might be correlated with translocation of dogs associated with humans. Interconnecting factors between human socioeconomic and population density might determine the transmission dynamics of virus in a rural-to-urban polarity. The presence of 2 or more rabies virus groups in a location might be indicative of a gene flow, reflecting a translocation of dogs within such region and adjacent areas. Different approaches may be required for rabies control based on the homo- or heterogeneity of the virus. Areas containing homogeneous virus populations should be targeted first. Control of dog movement associated with humans is essential. PMID:15985183

  5. Development of a dynamic thermal model process

    SciTech Connect

    Smith, F. R.

    1996-04-01

    A dynamic electrical-thermal modeling simulation technique was developed to allow up-front design of thermal and electronic packaging with a high degree of accuracy and confidence. We are developing a hybrid multichip module output driver which controls with power MOSFET driver circuits. These MOSFET circuits will dissipate from 13 to 26 watts per driver in a physical package less than two square inches. The power dissipation plus an operating temperature range of -55{degrees} C to 100{degrees} C makes an accurate thermal package design critical. The project goal was to develop a simulation process to dynamically model the electrical/thermal characteristics of the power MOSFETS using the SABER analog simulator and the ABAQUS finite element simulator. SABER would simulate the electrical characteristics of the multi-chip module design while co-simulation is being done with ABAQUS simulating the solid model thermal characteristics of the MOSFET package. The dynamic parameters, MOSFET power and chip temperature, would be actively passed between simulators to effect a coupled simulator modelling technique. The project required a development of a SABER late for the analog ASIC controller circuit, a dynamic electrical/thermal template for the IRF150 and IRF9130 power MOSFETs, a solid model of the multi-chip module package, FORTRAN code to handle I/Q between and HP755 workstation and SABER, and I/O between CRAY J90 computer and ABAQUS. The simulation model was certified by measured electrical characteristics of the circuits and real time thermal imaging of the output multichip module.

  6. Mitochondrial dynamics and inheritance during cell division, development and disease

    PubMed Central

    Mishra, Prashant; Chan, David C.

    2014-01-01

    Preface During cell division, it is critical to properly partition functional sets of organelles to each daughter cell. The partitioning of mitochondria shares some common features with other organelles, particularly in their interactions with cytoskeletal elements to facilitate delivery to the daughter cells. However, mitochondria have unique features – including their own genome and a maternal mode of germline transmission – that place additional demands on this process. We discuss the mechanisms regulating mitochondrial segregation during cell division, oogenesis, fertilization and tissue development. The mechanisms that ensure the integrity of these organelles and their DNA include fusion-fission dynamics, organelle transport, mitophagy, and genetic selection of functional genomes. Defects in these processes can lead to cell and tissue pathologies. PMID:25237825

  7. Developing a Brief Scale to Measure HIV Transmission Risk Among Injecting Drug Users

    PubMed Central

    Shahesmaeili, Armita; Haghdoost, Ali Akbar; Soori, Hamid

    2015-01-01

    Background: One of the main concerns of policymakers is to measure the impact of harm reduction programs and different interventions on the risk of HIV transmission among Injecting Drug Users (IDUs). Looking simultaneously at multiple factors and conditions that affect the risk of HIV transmission may provide policymakers a better insight into the mixed nature of HIV transmission. Objectives: The present study aimed to design a simple, brief, and multi-dimensional scale for measuring HIV transmission risk among IDUs. Patients and Methods: From October 2013 to March 2014, we conducted face-to-face interviews with 147 IDUs. Eligible participants were individuals 18 years or older who had injected drugs at least once during the last year and had not participated in similar studies within the 2 months before the interview. To design a scale for measuring HIV transmission risk, we specified 11 items, which address different dimensions of HIV risk taking behaviors/situations based on experts’ opinion. We applied exploratory factor analysis (EFA) with principal component extraction to develop scales. Eigen values greater than 1 were used as a criterion for factor extraction. Results: We extracted 7 items based on first factor, which were accounted for 21% of the variations. The final scale contained 7 items: 4 items were related to injecting practice and 3 items related to sexual behaviors. The Cronbach’s α coefficient was 0.66, acceptable for such a brief scale. Conclusions: Applying a simple and brief scale that incorporates the different dimensions of HIV transmission risk may provide policymakers and harm reductionists with a better understanding of HIV transmission in this key group and may be advantageous for evaluating intervention programs. PMID:26870713

  8. Phylogenetic studies of transmission dynamics in generalized HIV epidemics: An essential tool where the burden is greatest?

    PubMed Central

    Dennis, Ann M.; Herbeck, Joshua T.; Brown, Andrew Leigh; Kellam, Paul; de Oliveira, Tulio; Pillay, Deenan; Fraser, Christophe; Cohen, Myron S.

    2014-01-01

    Efficient and effective HIV prevention measures for generalized epidemics in sub-Saharan Africa have not yet been validated at the population-level. Design and impact evaluation of such measures requires fine-scale understanding of local HIV transmission dynamics. The novel tools of HIV phylogenetics and molecular epidemiology may elucidate these transmission dynamics. Such methods have been incorporated into studies of concentrated HIV epidemics to identify proximate and determinant traits associated with ongoing transmission. However, applying similar phylogenetic analyses to generalized epidemics, including the design and evaluation of prevention trials, presents additional challenges. Here we review the scope of these methods and present examples of their use in concentrated epidemics in the context of prevention. Next, we describe the current uses for phylogenetics in generalized epidemics, and discuss their promise for elucidating transmission patterns and informing prevention trials. Finally, we review logistic and technical challenges inherent to large-scale molecular epidemiological studies of generalized epidemics, and suggest potential solutions. PMID:24977473

  9. Development of an accurate transmission line fault locator using the global positioning system satellites

    NASA Technical Reports Server (NTRS)

    Lee, Harry

    1994-01-01

    A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

  10. The Effect of Antibody-Dependent Enhancement on the Transmission Dynamics and Persistence of Multiple-Strain Pathogens

    NASA Astrophysics Data System (ADS)

    Ferguson, Neil; Anderson, Roy; Gupta, Sunetra

    1999-01-01

    Cross-reactive antibodies produced by a mammalian host during infection by a particular microparasitic strain usually have the effect of reducing the probability of the host being infected by a different, but closely related, pathogen strain. Such cross-reactive immunological responses thereby induce between-strain competition within the pathogen population. However, in some cases such as dengue virus, evidence suggests that cross-reactive antibodies act to enhance rather than restrict the severity of a subsequent infection by another strain. This cooperative mechanism is thought to explain why pre-existing immunity to dengue virus is an important risk factor for the development of severe disease (i.e., dengue shock syndrome and dengue hemorrhagic fever). In this paper, we explore the effect of antibody-dependent enhancement on the transmission dynamics of multistrain pathogen populations. We show that enhancement frequently may generate complex and persistent cyclical or chaotic epidemic behavior. Furthermore, enhancement acts to permit the coexistence of all strains where in its absence only one or a subset would persist.

  11. Transmission Dynamics of Rift Valley Fever Virus: Effects of Live and Killed Vaccines on Epizootic Outbreaks and Enzootic Maintenance

    PubMed Central

    Chamchod, Farida; Cosner, Chris; Cantrell, R. Stephen; Beier, John C.; Ruan, Shigui

    2016-01-01

    Rift Valley fever virus (RVFV) is an arthropod-borne viral pathogen that causes significant morbidity and mortality in small ruminants throughout Africa and the Middle East. Due to the sporadic and explosive nature of RVF outbreaks, vaccination has proved challenging to reduce RVFV infection in the ruminant population. Currently, there are two available types of vaccines, live and killed, in endemic areas. In this study, two mathematical models have been developed to explore the impact of live and killed vaccines on the transmission dynamics of RVFV. We demonstrate in general that vaccination helps reduce the severity of RVF outbreaks and that less delay in implementation and more vaccination attempts and effective vaccines can reduce the outbreak magnitude and the endemic number of RVFV. However, an introduction of a number of ruminants vaccinated by live vaccines in RVFV-free areas may cause an outbreak and RVFV may become endemic if there is sustained use of live vaccines. Other factors that are the important determinants of RVF outbreaks include: unsustained vaccination programs, recruitment of susceptible ruminants, and the seasonal abundance of mosquitoes. PMID:26869999

  12. Effects of gear box vibration and mass imbalance on the dynamics of multi-stage gear transmissions

    NASA Technical Reports Server (NTRS)

    Choy, Fred K.; Tu, Yu K.; Zakrajsek, James J.; Townsend, Dennis P.

    1991-01-01

    The dynamic behavior of multistage gear transmission system, with the effects of gear-box-induced vibrations and rotor mass-imbalances is analyzed. The model method, using undamped frequencies and planar mode shapes, is used to reduce the degree-of-freedom of the system. The various rotor-bearing stages as well as lateral and torsional vibrations of each individual stage are coupled through localized gear-mesh-tooth interactions. Gear-box vibrations are coupled to the gear stage dynamics through bearing support forces. Transient and steady state dynamics of lateral and torsional vibrations of the geared system are examined in both time and frequency domain. A typical three-staged geared system is used as an example. Effects of mass-imbalance and gear box vibrations on the system dynamic behavior are presented in terms of modal excitation functions for both lateral and torsional vibrations. Operational characteristics and conclusions are drawn from the results presented.

  13. Development of Dynamically Optimized Wireless Transmission System for Wireless Sensor Networks in Highrise Apartment Building Heating Systems / Optimizētas Dinamiskās Bezvadu Sensoru Tīklu Pārraides Risinājuma Izstrāde Daudzstāvu Ēku Apkures Sistēmas Parametru Izgūšanai Un Vadībai

    NASA Astrophysics Data System (ADS)

    Isakovs, V.; Kondratjevs, K.; Kunicina, N.; Freliha, B.; Zabasta, A.

    2015-08-01

    Smart meters will be at the centre of the integrated solutions, including interaction with other networks in the next decade. The developed solution for multi-apartment building ventilation and heating parameter monitoring aims to increase energy efficiency and optimal control of the existing system. Dynamic control of heat and ventilation systems, heat loss detection, calculation and mitigation, and individual heat energy accounting are difficult tasks to accomplish. This article deals with the data transmission system using battery powered ISM band radio transmitters. The temperature measurement sensors with cumulative temperature reading are used as sensor part for this solution. The offered approach to monitoring system is used for overall building and individual apartment monitoring. Data coding and antenna designs are explained for this particular application. Daudzstāvu ēkas, kuras nav sākotnēji plānotas integrācijai ar ēku vadības sistēmām, rada kompleksu problemātisko vidi modernizācijai. Vadu sensoru sistēmu uzstādīšana šādās ēkās kļūst nepraktiska vai pat neiespējama. Šī iemesla dēļ ir nepieciešamas efektīvas bezvadu sensoru sistēmas, kas spētu nodrošināt mērījumu nogādi, ņemot vērā daudzstāvu ēku specifiku. Rakstā tiek piedāvāts bezvadu sensoru tīkla risinājums efektīvai datu pārraidei siltumapgādes sistēmas parametru izgūšanai. Tiek izstrādāta un aprobēta specializētā virziena antena efektīvai radio telegrammu savākšanai no dzīvokļiem, nogādājot mērījumus datu koncentratoros. Ziņojumu telegrammu efektīvai pārraidei tiek piedāvāta datu kodēšanas kumulatīvā metode. Piedāvātais risinājums pielietojams gan jaunām, gan esošām ēkām. Izgūtie dati ir pielietojami siltuma apgādes sistēmas uzraudzībai, regulēšanai, kā arī individuālā siltuma patēriņa tarifikācijai.

  14. Status of research and development for 1200-kV transmission and substation equipment

    SciTech Connect

    Walldorf, S.P.; Gnadt, P.A.

    1985-01-01

    In 1975 the US Department of Energy (DOE), Division of Electric Energy Systems (EES), initiated a program for the research and development (R and D) of 1200-kV transmission and substation equipment with a goal of developing the technology capable of three-phase power transfer of 10 GW. This R and D program has encompassed all the major and essential transmission cable, substation apparatus, and specialized instrumentation for a 1200-kV system; and it has produced a number of full-scale 1200-kV components that have successfully undergone or are still undergoing accelerated field testing. This paper presents a review of the overall DOE/EES 1200-kV R and D program, describes the major components developed, highlights their key design aspects, indicates the present status of development and testing, and presents a discussion of future commercial implications.

  15. Dynamic mapping of normal human hippocampal development.

    PubMed

    Gogtay, Nitin; Nugent, Tom F; Herman, David H; Ordonez, Anna; Greenstein, Deanna; Hayashi, Kiralee M; Clasen, Liv; Toga, Arthur W; Giedd, Jay N; Rapoport, Judith L; Thompson, Paul M

    2006-01-01

    The hippocampus, which plays an important role in memory functions and emotional responses, has distinct subregions subserving different functions. Because the volume and shape of the hippocampus are altered in many neuropsychiatric disorders, it is important to understand the trajectory of normal hippocampal development. We present the first dynamic maps to reveal the anatomical sequence of normal human hippocampal development. A novel hippocampal mapping technique was applied to a database of prospectively obtained brain magnetic resonance imaging (MRI) scans (100 scans in 31 children and adolescents), scanned every 2 yr for 6-10 yr between ages 4 and 25. Our results establish that the structural development of the human hippocampus is remarkably heterogeneous, with significant differences between posterior (increase over time) and anterior (loss over time) subregions. These distinct developmental trajectories of hippocampal subregions may parallel differences in their functional development. PMID:16826559

  16. New developments in relativistic dissipative fluid dynamics

    NASA Astrophysics Data System (ADS)

    Muronga, Azwinndini

    2010-09-01

    The recent notion of the perfect fluid created at the relativistic heavy ion collider (RHIC) has been embraced by many experimentalists and theorists alike. However, much of the evidence to this notion has been based on the success of describing some experimental observables by non-viscous hydrodynamics or by small shear viscosity to entropy density ratio. Developments on viscous hydrodynamics evolved from (0+1) dimensions (Bjorken scaling solution) over (1+1) dimensions (Bjorken + transverse flow) to (2+1) dimensions (elliptic flow) and currently (3+1) dimensions. There still exist some formal issues concerning the allowed form of the relativistic viscous hydrodynamic equations and what effects the new additional or higher order terms will have on the spacetime evolution and the experimental observables. Starting with a brief introduction of the basics of relativsitic fluid dynamics, I will discuss our current knowledge of relativistic theory of fluid dynamics in the presence of dissipative fluxes.

  17. Dynamic modeling of herpes simplex virus type-2 (HSV-2) transmission: issues in structural uncertainty.

    PubMed

    Foss, Anna M; Vickerman, Peter T; Chalabi, Zaid; Mayaud, Philippe; Alary, Michel; Watts, Charlotte H

    2009-04-01

    The sexually transmitted infection (STI) Herpes simplex virus type-2 (HSV-2) is of public health concern because it is a very common frequently unrecognized lifelong infection, which may facilitate HIV transmission. Within HIV/STI modeling, structural uncertainty has received less attention than parametric uncertainty. By merging the compartments of a "complex" model, a "simple" HSV-2 model is developed. Sexual interactions between female sex workers (FSWs) and clients are modeled using data from India. Latin Hypercube Sampling selects from parameter distributions and both models are run for each of the 10,000 parameter sets generated. Outputs are compared (except for 2,450 unrealistic simulations). The simple model is a good approximation to the complex model once the HSV-2 epidemic has reached 60% of the equilibrium prevalence (95% of the 7,550 runs produced <10% relative error). The simple model is a reduced version of the complex model that retains details implicitly. For late-stage epidemics, the simple model gives similar prevalence trends to the complex model. As HSV-2 epidemics in many populations are advanced, the simple model is accurate in most instances, although the complex model may be preferable for early epidemics. The analysis highlights the issue of structural uncertainty and the value of reducing complexity. PMID:19219511

  18. The biology of sexual development of Plasmodium: the design and implementation of transmission-blocking strategies

    PubMed Central

    2012-01-01

    A meeting to discuss the latest developments in the biology of sexual development of Plasmodium and transmission-control was held April 5-6, 2011, in Bethesda, MD. The meeting was sponsored by the Bill & Melinda Gates Foundation and the National Institutes of Health, National Institute of Allergy and Infectious Diseases (NIH/NIAID) in response to the challenge issued at the Malaria Forum in October 2007 that the malaria community should re-engage with the objective of global eradication. The consequent rebalancing of research priorities has brought to the forefront of the research agenda the essential need to reduce parasite transmission. A key component of any transmission reduction strategy must be methods to attack the parasite as it passes from man to the mosquito (and vice versa). Such methods must be rationally based on a secure understanding of transmission from the molecular-, cellular-, population- to the evolutionary-levels. The meeting represented a first attempt to draw together scientists with expertise in these multiple layers of understanding to discuss the scientific foundations and resources that will be required to provide secure progress toward the design and successful implementation of effective interventions. PMID:22424474

  19. Deviant Socialization Mediates Transmissible and Contextual Risk on Cannabis Use Disorder Development: A Prospective Study

    PubMed Central

    Tarter, Ralph E.; Fishbein, Diana; Kirisci, Levent; Mezzich, Ada; Ridenour, Ty; Vanyukov, Michael

    2011-01-01

    Aims This study examined the contribution of transmissible risk, in conjunction with family and peer contextual factors during childhood and adolescence, on development of cannabis use disorder in adulthood. Design The family high risk design was used to recruit proband fathers with and without substance use disorder and longitudinally track their sons from late childhood to adulthood. Setting The families were recruited under aegis of the Center for Education and Drug Abuse Research in Pittsburgh, Pennsylvania. Participants The oldest son in the family was studied at ages 10–12, 16, 19, and 22. Measurements The transmissible liability index (TLI) (Vanyukov et al., 2009) along with measures of quality of parent child relationship, cooperative behavior at home, social attitudes, and peer milieu were administered to model the developmental pathway to cannabis use disorder. Findings Affiliation with socially deviant peers and harboring non-normative attitudes (age 16) mediate the association between transmissible risk for SUD (age 10–12) and use of illegal drugs (age 19) leading to cannabis use disorder (age 22). Conclusions Deviant socialization resulting from transmissible risk and poor parent-child relationship is integral to development of cannabis use disorder in young adulthood. PMID:21320228

  20. Vancomycin-resistant enterococci in intensive-care hospital settings: Transmission dynamics, persistence, and the impact of infection control programs

    PubMed Central

    Austin, Daren J.; Bonten, Marc J. M.; Weinstein, Robert A.; Slaughter, Sarah; Anderson, Roy M.

    1999-01-01

    Vancomycin-resistant enterococci (VRE) recently have emerged as a nosocomial pathogen especially in intensive-care units (ICUs) worldwide. Transmission via the hands of health-care workers is an important determinant of spread and persistence in a VRE-endemic ICU. We describe the transmission of nosocomial pathogens by using a micro-epidemiological framework based on the transmission dynamics of vector-borne diseases. By using the concept of a basic reproductive number, R0, defined as the average number of secondary cases generated by one primary case, we show quantitatively how infection control measures such as hand washing, cohorting, and antibiotic restriction affect nosocomial cross-transmission. By using detailed molecular epidemiological surveillance and compliance monitoring, we found that the estimated basic reproductive number for VRE during a study at the Cook County Hospital, Chicago, was approximately 3–4 without infection control and 0.7 when infection control measures were included. The impact of infection control was to reduce the prevalence from a predicted 79% to an observed 36%. Hand washing and staff cohorting are the most powerful control measures although their efficacy depends on the magnitude of R0. Under the circumstances tested, endemicity of VRE was stabilized despite infection control measures, by the constant introduction of colonized patients. Multiple stochastic simulations of the model revealed excellent agreement with observed pattern. In conjunction with detailed microbiological surveillance, a mathematical framework provides a precise template to describe the colonization dynamics of VRE in ICUs and impact of infection control measures. Our analyses suggest that compliance for hand washing significantly in excess of reported levels, or the cohorting of nursing staff, are needed to prevent nosocomial transmission of VRE in endemic settings. PMID:10359812

  1. Development on dynamic nuclear polarized targets.

    SciTech Connect

    Penttila, S. I.

    2002-01-01

    Our interest in understanding the spin content of the nucleon has left its marks on the recent development, of the dynamic nuclear polarized (DNP) targets. This can be seen from the targets developed at CERN and SLAC for the measurement of the polarized spin structure functions in deep inelastic scattering. The results of the experiments indicated that less than 30% of the nucleon spin is carried by the quarks. This unpredicted small value initiated planning of new polarized target experiments to determine the gluon polarization on the nucleon using polarized real photons and polarized 'LiD targets. In several facilities very intense polarized photon beams are available at a wide energy range. During the next few years these photon beanis with DNP targets will be used to test the fundamental GDH sum rule. Other DNP target developments are also discussed.

  2. Development of a dynamic pressure calibration technique

    NASA Technical Reports Server (NTRS)

    Vezzetti, C. F.; Hilten, J. S.; Lederer, P. S.

    1975-01-01

    The report deals with work continuing on the development of a method of producing sinusoidally varying pressures of at least 34 kPa zero-to-peak with amplitude variations within plus or minus 5% up to 2 kHz for the dynamic calibration of pressure transducers. Sinusoidally varying pressures of 34 kPa zero-to-peak were produced between 40 Hz and 750 Hz by vibrating a 10-cm column of a dimethyl siloxane liquid at 36gn zero-to-peak. Damping of the liquid column was accomplished by packing the fixture tube with a number of smaller diameter tubes.

  3. Intergenerational Transmission of Adaptive Functioning: A Test of the Interactionist Model of SES and Human Development

    ERIC Educational Resources Information Center

    Schofield, Thomas J; Martin, Monica J.; Conger, Katherine J.; Neppl, Tricia M.; Donnellan, M. Brent; Conger, Rand D.

    2011-01-01

    The interactionist model (IM) of human development (R. D. Conger & M. B. Donellan, 2007) proposes that the association between socioeconomic status (SES) and human development involves a dynamic interplay that includes both social causation (SES influences human development) and social selection (individual characteristics affect SES). Using a…

  4. An assay to probe Plasmodium falciparum growth, transmission stage formation and early gametocyte development

    PubMed Central

    Brancucci, Nicolas M B; Goldowitz, Ilana; Buchholz, Kathrin; Werling, Kristine; Marti, Matthias

    2015-01-01

    Conversion from asexual proliferation to sexual differentiation initiates the production of the gametocyte, which is the malaria parasite stage required for human-to-mosquito transmission. This protocol describes an assay designed to probe the effect of drugs or other perturbations on asexual replication, sexual conversion and early gametocyte development in the major human malaria parasite Plasmodium falciparum. Synchronized asexually replicating parasites are induced for gametocyte production by the addition of conditioned medium, and they are then exposed to the treatment of interest during sexual commitment or at any subsequent stage of early gametocyte development. Flow cytometry is used to measure asexual proliferation and gametocyte production via DNA dye staining and the gametocyte-specific expression of a fluorescent protein, respectively. This screening approach may be used to identify and evaluate potential transmission-blocking compounds and to further investigate the mechanism of sexual conversion in malaria parasites. The full protocol can be completed in 11 d. PMID:26134953

  5. Recent developments of the in situ wet cell technology for transmission electron microscopies

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Li, Chang; Cao, Hongling

    2015-03-01

    In situ wet cells for transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) allow studying structures and processes in a liquid environment with high temporal and spatial resolutions, and have been attracting increasing research interests in many fields. In this review, we highlight the structural and functional developments of the wet cells for TEM and STEM. One of the key features of the wet cells is the sealing technique used to isolate the liquid sample from the TEM/STEM vacuum environments, thus the existing in situ wet cells are grouped by different sealing methods. In this study, the advantages and shortcomings of each type of in situ wet cells are discussed, the functional developments of different wet cells are presented, and the future trends of the wet cell technology are addressed. It is suggested that in the future the in situ wet cell TEM/STEM technology will have an increasing impact on frontier nanoscale research.

  6. Development of a model of an x-ray tube transmission source

    SciTech Connect

    Goda, Joetta M; Ianakiev, Kiril D; Moss, Cal E

    2009-01-01

    In support of the development of an x-ray tube based source for transmission measurements of UF6 gas, we have developed a one-dimensional, spreadsheet-based model of the source. Starting with the spectrum produced by an x-ray tube we apply the linear attenuation coefficients for various notch filters, the aluminum pipe, and UF6 gas. This model allows calculation of the transmitted spectrum based on the type of filter, the thickness of the filter, the x-ray tube high voltage, the Al pipe thickness, and the UF6 gas pressure. The sensitivity of the magnitude of the transmission peak produced by the notch filter to any of these variables can be explored quickly and easily to narrow the choices for experimental measurements. To validate the spreadsheet based model, comparisons have been made to various experimental data.

  7. Toward the development of effective transmission-blocking vaccines for malaria.

    PubMed

    Nikolaeva, Daria; Draper, Simon J; Biswas, Sumi

    2015-05-01

    The continued global burden of malaria can in part be attributed to a complex lifecycle, with both human hosts and mosquito vectors serving as transmission reservoirs. In preclinical models of vaccine-induced immunity, antibodies to parasite sexual-stage antigens, ingested in the mosquito blood meal, can inhibit parasite survival in the insect midgut as judged by ex vivo functional studies such as the membrane feeding assay. In an era of renewed political momentum for malaria elimination and eradication campaigns, such observations have fueled support for the development and implementation of so-called transmission-blocking vaccines. While leading candidates are being evaluated using a variety of promising vaccine platforms, the field is also beginning to capitalize on global '-omics' data for the rational genome-based selection and unbiased characterization of parasite and mosquito proteins to expand the candidate list. This review covers the progress and prospects of these recent developments. PMID:25597923

  8. The dynamic landscape of exceptional language development.

    PubMed

    Peltzer-Karpf, Annemarie

    2012-06-01

    Developmental neurocognitive studies have shown that the brain systems supporting the emergence of sensory and cognitive abilities display different profiles of neuroplasticity. The research question posed here is to what extent sensory deprivation influences the dynamics of language development. The findings reported are grounded in studies with vision-impaired children with sighted peers featured as controls (age range 18 months to 3 years). Their data are matched against findings on advanced language development in blind children (age range: from 6 to 10 years; N = 12) and hearing-impaired and deaf children (age range: from 5 to 11 years; N = 20). The data give evidence that language acquisition in sensory-impaired children follows the same overall developmental path with respect to macrostructural changes and the succession of phase-shifts. System-specific temporal discrepancies expressed in protracted phase-shifts and delayed increases of variability are most evident in the early phases. Self-organizing maps (SOMs) help to visualize individual and group-specific variation. The dynamic framework used (1) shows a higher sensibility to system-specific changes, (2) enhances the informative value of the data assessed, and (3) facilitates reliable prognoses concerning the child's cognitive and linguistic future. PMID:22612355

  9. The tortoise or the hare? Impacts of within-host dynamics on transmission success of arthropod-borne viruses.

    PubMed

    Althouse, Benjamin M; Hanley, Kathryn A

    2015-08-19

    Arthropod-borne viruses (arboviruses) are maintained in a cycle of alternating transmission between vertebrate hosts and arthropod vectors. Arboviruses possess RNA genomes capable of rapid diversification and adaptation, and the between-host trade-offs inherent to host alternation impose well-documented constraints on arbovirus evolution. Here, we investigate the less well-studied within-host trade-offs that shape arbovirus replication dynamics and transmission. Arboviruses generally establish lifelong infection in vectors but transient infection of variable magnitude (i.e. peak virus concentration) and duration in vertebrate hosts. In the majority of experimental infections of vertebrate hosts, both the magnitude and duration of arbovirus replication depended upon the dose of virus administered, with increasing dose resulting in greater magnitude but shorter duration of viraemia. This pattern suggests that the vertebrate immune response imposes a trade-off between the height and breadth of the virus replication curve. To investigate the impact of this trade-off on transmission, we used a simple modelling approach to contrast the effect of 'tortoise' (low magnitude, long duration viraemia) and 'hare' (high magnitude, short duration viraemia) arbovirus replication strategies on transmission. This model revealed that, counter to previous theory, arboviruses that adopt a tortoise strategy have higher rates of persistence in both host and vector populations. PMID:26150665

  10. Dynamics and control of Ebola virus transmission in Montserrado, Liberia: a mathematical modeling analysis

    PubMed Central

    Lewnard, Joseph A.; Ndeffo Mbah, Martial L.; Alfaro-Murillo, Jorge A.; Altice, Frederick L.; Bawo, Luke; Nyenswah, Tolbert G.; Galvani, Alison P.

    2014-01-01

    Background A substantial scale-up in public health response is needed to control the unprecedented Ebola virus disease (EVD) epidemic in West Africa. Current international commitments seek to expand intervention capacity in three areas: new EVD Treatment Centers (ETCs); case ascertainment through contact tracing; and household protective kit allocation. Methods We developed a transmission model of Ebola virus that we fitted to reported EVD cases and deaths in Montserrado County, Liberia. We used this model to evaluate effectiveness of expanding ETCs, improving case ascertainment, and allocating protective kits for controlling the outbreak in Montserrado. Findings We estimated the basic reproductive number for EVD in Montserrado to be 2·49 [2·38–2·60]. We expect that allocating 4,800 additional ETC beds and increasing case ascertainment fivefold in November can avert 77312 [68400–85870] cases relative to the status quo by 15 December. Complementing these measures with protective kit allocation increases the expectation as high as 97940 [90096–105606] cases. If deployed by 15 October, equivalent interventions would have been expected to avert 137432 [129736–145874] cases. If delayed to 15 November, we expect the interventions will at best avert 53957 [49963–60490] cases. Interpretation The number of ETC beds needed to effectively control EVD in Montserrado substantially exceeds the total pledged by the United States to West Africa. Accelerated case ascertainment is required to maximize effectiveness of expanding ETC capacity. Distributing protective kits can further augment EVD prevention. Our findings highlight the rapidly closing window of opportunity for controlling the outbreak and averting a catastrophic toll of EVD cases and deaths. Funding NIH: U01-GM087719, U01-GM105627, K24-DA017072 PMID:25455986

  11. Dynamic epithelia of the developing vertebrate face

    PubMed Central

    Choe, Chong Pyo; Crump, J. Gage

    2015-01-01

    A segmental series of endoderm-derived pouch and ectoderm-derived cleft epithelia act as signaling centers in the developing face. Their precise morphogenesis is therefore essential for proper patterning of the vertebrate head. Intercellular adhesion and polarity are highly dynamic within developing facial epithelial cells, with signaling from the adjacent mesenchyme controlling both epithelial character and directional migration. Endodermal and ectodermal epithelia fuse to form the primary mouth and gill slits, which involves basement membrane dissolution, cell intercalations, and apoptosis, as well as undergo further morphogenesis to generate the middle ear cavity and glands of the neck. Recent studies of facial epithelia are revealing both core programs of epithelial morphogenesis and insights into the coordinated assembly of the vertebrate head. PMID:25748249

  12. Transmission Dynamics of the Etiological Agent of SARS in Hong Kong: Impact of Public Health Interventions

    NASA Astrophysics Data System (ADS)

    Riley, Steven; Fraser, Christophe; Donnelly, Christl A.; Ghani, Azra C.; Abu-Raddad, Laith J.; Hedley, Anthony J.; Leung, Gabriel M.; Ho, Lai-Ming; Lam, Tai-Hing; Thach, Thuan Q.; Chau, Patsy; Chan, King-Pan; Lo, Su-Vui; Leung, Pak-Yin; Tsang, Thomas; Ho, William; Lee, Koon-Hung; Lau, Edith M. C.; Ferguson, Neil M.; Anderson, Roy M.

    2003-06-01

    We present an analysis of the first 10 weeks of the severe acute respiratory syndrome (SARS) epidemic in Hong Kong. The epidemic to date has been characterized by two large clusters-initiated by two separate ``super-spread'' events (SSEs)-and by ongoing community transmission. By fitting a stochastic model to data on 1512 cases, including these clusters, we show that the etiological agent of SARS is moderately transmissible. Excluding SSEs, we estimate that 2.7 secondary infections were generated per case on average at the start of the epidemic, with a substantial contribution from hospital transmission. Transmission rates fell during the epidemic, primarily as a result of reductions in population contact rates and improved hospital infection control, but also because of more rapid hospital attendance by symptomatic individuals. As a result, the epidemic is now in decline, although continued vigilance is necessary for this to be maintained. Restrictions on longer range population movement are shown to be a potentially useful additional control measure in some contexts. We estimate that most currently infected persons are now hospitalized, which highlights the importance of control of nosocomial transmission.

  13. Modeling the trade-off between transmissibility and contact in infectious disease dynamics.

    PubMed

    Lin, Chiu-Ju; Deger, Kristen A; Tien, Joseph H

    2016-07-01

    Symptom severity affects disease transmission both by impacting contact rates, as well as by influencing the probability of transmission given contact. This involves a trade-off between these two factors, as increased symptom severity will tend to decrease contact rates, but increase the probability of transmission given contact (as pathogen shedding rates increase with symptom severity). This paper explores this trade-off between contact and transmission given contact, using a simple compartmental susceptible-infected-recovered type model. Under mild assumptions on how contact and transmission probability vary with symptom severity, we give sufficient, biologically intuitive criteria for when the basic reproduction number varies non-monotonically with symptom severity. Multiple critical points are possible. We give a complete characterization of the region in parameter space where multiple critical points are located in the special case where contact rate decreases exponentially with symptom severity. We consider a multi-strain version of the model with complete cross-immunity and no super-infection. In this model, we prove that the strain with highest basic reproduction number drives the other strains to extinction. This has both evolutionary and epidemiological implications, including the possibility of an intervention paradoxically resulting in increased infection prevalence. PMID:27102055

  14. Development of Fault Point Locating System for Underground Transmission Lines using Optical Fiber Current Sensors

    NASA Astrophysics Data System (ADS)

    Kurosawa, Kiyoshi; Kondo, Reishi; Nasukawa, Shinsuke; Yamaguchi, Tatsushi; Amano, Kazuo

    Fault point locating systems based on surge current detection have recently been used for fast recovery of underground transmission line from the fault. Electromagnetic induction type sensors have mainly been used for detection of the surge current. However they are susceptible to electromagnetic noise which causes unstable system operation. To solve this problem, Tokyo Electric Power Co., Toko Electric Corporation and Fujikura Ltd., by a joint research, have developed a new system that applies optical fiber current sensors.

  15. Unsafe injections in the developing world and transmission of bloodborne pathogens: a review.

    PubMed

    Simonsen, L; Kane, A; Lloyd, J; Zaffran, M; Kane, M

    1999-01-01

    Unsafe injections are suspected to occur routinely in developing countries. We carried out a literature review to quantify the prevalence of unsafe injections and to assess the disease burden of bloodborne infections attributable to this practice. Quantitative information on injection use and unsafe injections (defined as the reuse of syringe or needle between patients without sterilization) was obtained by reviewing the published literature and unpublished WHO reports. The transmissibility of hepatitis B and C viruses and human immunodeficiency virus (HIV) was estimated using data from studies of needle-stick injuries. Finally, all epidemiological studies that linked unsafe injections and bloodborne infections were evaluated to assess the attributable burden of bloodborne infections. It was estimated that each person in the developing world receives 1.5 injections per year on average. However, institutionalized children, and children and adults who are ill or hospitalized, including those infected with HIV, are often exposed to 10-100 times as many injections. An average of 95% of all injections are therapeutic, the majority of which were judged to be unnecessary. At least 50% of injections were unsafe in 14 of 19 countries (representing five developing world regions) for which data were available. Eighteen studies reported a convincing link between unsafe injections and the transmission of hepatitis B and C, HIV, Ebola and Lassa virus infections and malaria. Five studies attributed 20-80% of all new hepatitis B infections to unsafe injections, while three implicated unsafe injections as a major mode of transmission of hepatitis C. In conclusion, unsafe injections occur routinely in most developing world regions, implying a significant potential for the transmission of any bloodborne pathogen. Unsafe injections currently account for a significant proportion of all new hepatitis B and C infections. This situation needs to be addressed immediately, as a political

  16. Development of Radar Navigation and Radio Data Transmission for Microhole Coiled Tubing Bottom Hole Assemblies

    SciTech Connect

    Larry G. Stolarczyk; Gerald L. Stolarczyk; Larry Icerman; John Howard; Hooman Tehrani

    2007-03-25

    This Final Technical Report summarizes the research and development (R&D) work performed by Stolar Research Corporation (Stolar) under U.S. Department of Energy (DOE) Contract Number DE-FC26-04NT15477. This work involved the development of radar navigation and radio data transmission systems for integration with microhole coiled tubing bottom hole assemblies. Under this contract, Stolar designed, fabricated, and laboratory and field tested two advanced technologies of importance to the future growth of the U.S. oil and gas industry: (1) real-time measurement-while-drilling (MWD) for guidance and navigation of coiled tubing drilling in hydrocarbon reservoirs and (2) two-way inductive radio data transmission on coiled tubing for real-time, subsurface-to-surface data transmission. The operating specifications for these technologies are compatible with 3.5-inch boreholes drilled to a true vertical depth (TVD) of 5,000 feet, which is typical of coiled tubing drilling applications. These two technologies (i.e., the Stolar Data Transmission System and Drill String Radar) were developed into pre-commercial prototypes and tested successfully in simulated coiled tubing drilling conditions. Integration of these two technologies provides a real-time geosteering capability with extremely quick response times. Stolar is conducting additional work required to transition the Drill String Radar into a true commercial product. The results of this advanced development work should be an important step in the expanded commercialization of advanced coiled tubing microhole drilling equipment for use in U.S. hydrocarbon reservoirs.

  17. Development of fault section detecting system for gas insulated transmission lines

    SciTech Connect

    Nakamura, E.; Uchida, K.; Koshilishi, M.; Mitsui, T.; Miyamoto, S.; Nakamura, K.; Itaka, K.; Hara, T.; Yoda, T.

    1986-01-01

    A fault section detecting system using optical magnetic field sensors developed for gas insulated transmission lines (GIL) is reported. A bismuth silicon oxide (Bi/sub 12/SiO/sub 20/, or BSO) single crystal was adopted for the optical magnetic field sensor. A method of mounting the sensors to GIL which enables the sensors to detect the conductor current from outside the enclosure was developed. With the developed fault detector, faults occurring inside a section of GIL between sensors are detected by discriminating the phases of conductor currents detected by the sensors. The system was confirmed to have sufficient performance for application to commerical GILS.

  18. Development of a full-scale transmission testing procedure to evaluate advanced lubricants

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Decker, Harry J.; Shimski, John T.

    1992-01-01

    Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500-hp Helicopter Transmission Test Stand. The testing was part of a joint Navy/NASA/Army lubrication program. The objective of the program was to develop a separate lubricant for gearboxes and demonstrate an improved performance in life and load-carrying capacity. The goal of the experiments was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 base reference oil, then run identical tests with improved lubricants and demonstrate performance. The tests were directed at failing components that the Navy has had problems with due to marginal lubrication. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hours of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring.

  19. Study of the kinematic and dynamic characteristics of a wormgear transmission for helicopter applications

    NASA Technical Reports Server (NTRS)

    Sun, D. C.; Yuan, Qin

    1994-01-01

    The first phase of the study of the performance of a wormgear transmission is reported. In this phase the work included the selection of a double-enveloping wormgear type, and its dimensions, suitable for use in helicopter transmissions; the 3-D graphics representation of the selected wormgear using the I-DEAS software; the analysis of the kinematics of meshing; the analysis of load sharing among the meshing teeth; and the implementation of the analyses in a computer program. The report describes the analyses, their results, and the use of the computer programs.

  20. Estimation of the dynamics and rate of transmission of classical swine fever (hog cholera) in wild pigs.

    PubMed Central

    Hone, J.; Pech, R.; Yip, P.

    1992-01-01

    Infectious diseases establish in a population of wildlife hosts when the number of secondary infections is greater than or equal to one. To estimate whether establishment will occur requires extensive experience or a mathematical model of disease dynamics and estimates of the parameters of the disease model. The latter approach is explored here. Methods for estimating key model parameters, the transmission coefficient (beta) and the basic reproductive rate (RDRS), are described using classical swine fever (hog cholera) in wild pigs as an example. The tentative results indicate that an acute infection of classical swine fever will establish in a small population of wild pigs. Data required for estimation of disease transmission rates are reviewed and sources of bias and alternative methods discussed. A comprehensive evaluation of the biases and efficiencies of the methods is needed. PMID:1582476

  1. Dynamics of Centrocestus armatus Transmission in Endemic River in Hyogo Prefecture, Japan

    PubMed Central

    Komatsu, Shintaro; Kimura, Daisuke; Paller, Vachel Gay V.; Uga, Shoji

    2014-01-01

    Centrocestus armatus is an intestinal parasite belonging to the family Heterophyidae. We developed an apparatus for recovering cercariae and clarified the infection dynamics of this parasite. To clarify the circadian rhythm of cercarial shedding in the summer season, we filtrated 30 l of river water every 2 h for 24 h. Cercariae were first detected between 06:00 and 08:00 h, increased over time to reach peak at 16:00 h and decreased thereafter, thus showing a single-peak pattern. In a survey of seasonal change, approximately 200 cercariae were contained in 1 l of river water during the summer season, while none were found during the winter. This cercarial shedding pattern appeared to be related to sunrise/sunset and water/atmosphere temperature. Therefore, we examined whether cercarial shedding was affected by light or temperature changes under laboratory conditions, and confirmed that both light and temperature were important factors for cercarial shedding. Light was a stronger factor than water temperature. Cercarial shedding of C. armatus occurred in response to temperature and light. The change in the number of juvenile metacercariae detected in fish brain corresponded with monthly detection rates of cercariae; however, the incidence of new infections decreased in August. This suggests that Nipponocypris temminkii contains a defense mechanism against new infections that may have hindered the increase in parasite infectivity. These results clarified the smooth infection from the first to the second intermediate host of C. armatus in the endemic river. Throughout the study period, fecal samples were collected from 19 kites, 114 herons, and three unidentified species. However, our results using C. armatus showed a low value of 1% in herons and 5% in kites. The infection dynamics of final host to first intermediate host need to be further investigated. PMID:24808745

  2. Dynamics of Centrocestus armatus Transmission in Endemic River in Hyogo Prefecture, Japan.

    PubMed

    Komatsu, Shintaro; Kimura, Daisuke; Paller, Vachel Gay V; Uga, Shoji

    2014-03-01

    Centrocestus armatus is an intestinal parasite belonging to the family Heterophyidae. We developed an apparatus for recovering cercariae and clarified the infection dynamics of this parasite. To clarify the circadian rhythm of cercarial shedding in the summer season, we filtrated 30 l of river water every 2 h for 24 h. Cercariae were first detected between 06:00 and 08:00 h, increased over time to reach peak at 16:00 h and decreased thereafter, thus showing a single-peak pattern. In a survey of seasonal change, approximately 200 cercariae were contained in 1 l of river water during the summer season, while none were found during the winter. This cercarial shedding pattern appeared to be related to sunrise/sunset and water/atmosphere temperature. Therefore, we examined whether cercarial shedding was affected by light or temperature changes under laboratory conditions, and confirmed that both light and temperature were important factors for cercarial shedding. Light was a stronger factor than water temperature. Cercarial shedding of C. armatus occurred in response to temperature and light. The change in the number of juvenile metacercariae detected in fish brain corresponded with monthly detection rates of cercariae; however, the incidence of new infections decreased in August. This suggests that Nipponocypris temminkii contains a defense mechanism against new infections that may have hindered the increase in parasite infectivity. These results clarified the smooth infection from the first to the second intermediate host of C. armatus in the endemic river. Throughout the study period, fecal samples were collected from 19 kites, 114 herons, and three unidentified species. However, our results using C. armatus showed a low value of 1% in herons and 5% in kites. The infection dynamics of final host to first intermediate host need to be further investigated. PMID:24808745

  3. A Bird's Eye View of Influenza A Virus Transmission: Challenges with Characterizing Both Sides of a Co-Evolutionary Dynamic.

    PubMed

    Hill, Nichola J; Runstadler, Jonathan A

    2016-08-01

    In nature, wild birds and influenza A viruses (IAV) are continually co-evolving, locked into a back-and-forth of resistance and conquest that has approached a stable equilibrium over time. This co-evolutionary relationship between bird host and IAV may appear stable at the organismal level, but is highly dynamic at the molecular level manifesting in a constant trade-off between transmissibility and virulence of the virus. Characterizing both sides of the host-virus dynamic has presented a challenge for ecologists and virologists alike, despite the potential for this approach to provide insights into which conditions destabilize the equilibrium state resulting in outbreaks or mortality of hosts in extreme cases. The use of different methods that are either host-centric or virus-centric has made it difficult to reconcile the disparate fields of host ecology and virology for investigating and ultimately predicting wild bird-mediated transmission of IAV. This review distills some of the key lessons learned from virological and ecological studies and explores the promises and pitfalls of both approaches. Ultimately, reconciling ecological and virological approaches hinges on integrating scales for measuring host-virus interactions. We argue that prospects for finding common scales for measuring wild bird-influenza dynamics are improving due to advances in genomic sequencing, host-tracking technology and remote sensing data, with the unit of time (months, year, or seasons) providing a starting point for crossover. PMID:27252222

  4. Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)

    SciTech Connect

    LaGrange, T; Campbell, G H; Browning, N D; Reed, B W; Grummon, D S

    2010-03-01

    The crystallization processes of the as-deposited, amorphous NiTi thin films have been studied in detail using techniques such as differential scanning calorimetry and, in-situ TEM. The kinetic data have been analyzed in terms of Johnson-Mehl-Avrami-Kolomogrov (JMAK) semi-empirical formula. The kinetic parameters determined from this analysis have been useful in defining process control parameters for tailoring microstructural features and shape memory properties. Due to the commercial push to shrink thin film-based devices, unique processing techniques have been developed using laser-based annealing to spatially control the microstructure evolution down to sub-micron levels. Nanosecond, pulse laser annealing is particularly attractive since it limits the amount of peripheral heating and unwanted microstructural changes to underlying or surrounding material. However, crystallization under pulsed laser irradiation can differ significantly from conventional thermal annealing, e.g., slow heating in a furnace. This is especially true for amorphous NiTi materials and relevant for shape memory thin film based microelectromechanical systems (MEMS) applications. There is little to no data on the crystallization kinetics of NiTi under pulsed laser irradiation, primarily due to the high crystallization rates intrinsic to high temperature annealing and the spatial and temporal resolution limits of standard techniques. However, with the high time and spatial resolution capabilities of the dynamic transmission electron microscope (DTEM) constructed at Lawrence Livermore National Laboratory, the rapid nucleation events occurring from pulsed laser irradiation can be directly observed and nucleation rates can be quantified. This paper briefly explains the DTEM approach and how it used to investigate the pulsed laser induced crystallization processes in NiTi and to determine kinetic parameters.

  5. Respiratory virus transmission dynamics determine timing of asthma exacerbation peaks: Evidence from a population-level model.

    PubMed

    Eggo, Rosalind M; Scott, James G; Galvani, Alison P; Meyers, Lauren Ancel

    2016-02-23

    Asthma exacerbations exhibit a consistent annual pattern, closely mirroring the school calendar. Although respiratory viruses--the "common cold" viruses--are implicated as a principal cause, there is little evidence to link viral prevalence to seasonal differences in risk. We jointly fit a common cold transmission model and a model of biological and environmental exacerbation triggers to estimate effects on hospitalization risk. Asthma hospitalization rate, influenza prevalence, and air quality measures are available, but common cold circulation is not; therefore, we generate estimates of viral prevalence using a transmission model. Our deterministic multivirus transmission model includes transmission rates that vary when school is closed. We jointly fit the two models to 7 y of daily asthma hospitalizations in adults and children (66,000 events) in eight metropolitan areas. For children, we find that daily viral prevalence is the strongest predictor of asthma hospitalizations, with transmission reduced by 45% (95% credible interval =41-49%) during school closures. We detect a transient period of nonspecific immunity between infections lasting 19 (17-21) d. For adults, hospitalizations are more variable, with influenza driving wintertime peaks. Neither particulate matter nor ozone was an important predictor, perhaps because of the large geographic area of the populations. The school calendar clearly and predictably drives seasonal variation in common cold prevalence, which results in the "back-to-school" asthma exacerbation pattern seen in children and indirectly contributes to exacerbation risk in adults. This study provides a framework for anticipating the seasonal dynamics of common colds and the associated risks for asthmatics. PMID:26858436

  6. Training the Next Generation of Scientists: System Dynamics Modeling of Chagas Disease (American Trypanosomiasis) transmission.

    NASA Astrophysics Data System (ADS)

    Goff, P.; Hulse, A.; Harder, H. R.; Pierce, L. A.; Rizzo, D.; Hanley, J.; Orantes, L.; Stevens, L.; Justi, S.; Monroy, C.

    2015-12-01

    A computational simulation has been designed as an investigative case study by high school students to introduce system dynamics modeling into high school curriculum. This case study approach leads users through the forensics necessary to diagnose an unknown disease in a Central American village. This disease, Chagas, is endemic to 21 Latin American countries. The CDC estimates that of the 110 million people living in areas with the disease, 8 million are infected, with as many as 300,000 US cases. Chagas is caused by the protozoan parasite, Trypanosoma cruzi, and is spread via blood feeding insect (vectors), that feed on vertebrates and live in crevasses in the walls and roofs of adobe homes. One-third of the infected people will develop chronic Chagas who are asymptomatic for years before their heart or GI tract become enlarged resulting in death. The case study has three parts. Students play the role of WHO field investigators and work collaboratively to: 1) use genetics to identify the host(s) and vector of the disease 2) use a STELLA™ SIR (Susceptible, Infected, Recovered) system dynamics model to study Chagas at the village scale and 3) develop management strategies. The simulations identify mitigation strategies known as Ecohealth Interventions (e.g., home improvements using local materials) to help stakeholders test and compare multiple optima. High school students collaborated with researchers from the University of Vermont, Loyola University and Universidad de San Carlos, Guatemala, working in labs, interviewing researchers, and incorporating mulitple field data as part of a NSF-funded multiyear grant. The model displays stable equilibria of hosts, vectors, and disease-states. Sensitivity analyses show measures of household condition and presence of vertebrates were significant leverage points, supporting other findings by the University research team. The village-scale model explores multiple solutions to disease mitigation for the purpose of producing

  7. Development of a PLC modem for data transmission over a PWM power supply

    NASA Astrophysics Data System (ADS)

    Batard, Christophe; Ginot, Nicolas; Mannah, Marc Anthony; Millet, Christophe; Poitiers, Frédéric

    2014-04-01

    In variable-speed electrical drive and online conditioning monitoring, a feedback loop is required in order to transmit the sensor information from the motor to the controller close to the inverter. Additional cabling is used for signalling. This extra cabling has a significant cost and data transmission may not be reliable. Thus, the use of power line communication (PLC) technology to transmit data in motor drive application is quite interesting. The use of a PLC modem dedicated to the home network in a three-phase inverter-fed motor power cable does not work. Therefore, specific coupling interfaces are developed to transmit data through a pulse-width modulated power supply. Laboratory tests have shown that the couplers are operating properly. They ensure reliable data transmission in a motor drive application.

  8. Method development and validation for pharmaceutical tablets analysis using transmission Raman spectroscopy.

    PubMed

    Li, Yi; Igne, Benoît; Drennen, James K; Anderson, Carl A

    2016-02-10

    The objective of the study is to demonstrate the development and validation of a transmission Raman spectroscopic method using the ICH-Q2 Guidance as a template. Specifically, Raman spectroscopy was used to determine niacinamide content in tablet cores. A 3-level, 2-factor full factorial design was utilized to generate a partial least-squares model for active pharmaceutical ingredient quantification. Validation of the transmission Raman model was focused on figures of merit from three independent batches manufactured at pilot scale. The resultant model statistics were evaluated along with the linearity, accuracy, precision and robustness assessments. Method specificity was demonstrated by accurate determination of niacinamide in the presence of niacin (an expected related substance). The method was demonstrated as fit for purpose and had the desirable characteristics of very short analysis times (∼2.5s per tablet). The resulting method was used for routine content uniformity analysis of single dosage units in a stability study. PMID:26656945

  9. Dynamics of the natural transmission of bovine spongiform encephalopathy within an intensively managed sheep flock.

    PubMed

    Jeffrey, Martin; Witz, Janey P; Martin, Stuart; Hawkins, Steve A C; Bellworthy, Sue J; Dexter, Glenda E; Thurston, Lisa; González, Lorenzo

    2015-01-01

    Sheep are susceptible to the bovine spongiform encephalopathy (BSE) agent and in the UK they may have been exposed to BSE via contaminated meat and bone meal. An experimental sheep flock was established to determine whether ovine BSE could be naturally transmitted under conditions of intensive husbandry. The flock consisted of 113 sheep of different breeds and susceptible PRNP genotypes orally dosed with BSE, 159 sheep subsequently born to them and 125 unchallenged sentinel controls. BSE was confirmed in 104 (92%) orally dosed sheep and natural transmission was recorded for 14 of 79 (18%) lambs born to BSE infected dams, with rates varying according to PRNP genotype. The likelihood of natural BSE transmission was linked to stage of incubation period of the dam: the attack rate for lambs born within 100 days of the death of BSE infected dams was significantly higher (9/22, 41%) than for the rest (5/57, 9%). Within the group of ewes lambing close to death, those rearing infected progeny (n = 8, for 9/12 infected lambs) showed a significantly greater involvement of lymphoid tissues than those rearing non-infected offspring (n = 8, for 0/10 infected lambs). Horizontal transmission to the progeny of non-infected mothers was recorded only once (1/205, 0.5%). This low rate of lateral transmission was attributed, at least partly, to an almost complete absence of infected placentas. We conclude that, although BSE can be naturally transmitted through dam-lamb close contact, the infection in this study flock would not have persisted due to low-efficiency maternal and lateral transmissions. PMID:26511838

  10. Climatic variables and malaria transmission dynamics in Jimma town, South West Ethiopia

    PubMed Central

    2011-01-01

    Background:- In Ethiopia, malaria is seasonal and unstable, causing frequent epidemics. It usually occurs at altitudes < 2,000 m above sea level. Occasionally, transmission of malaria occurs in areas previously free of malaria, including areas > 2,000 m above sea level. For transmission of malaria parasite, climatic factors are important determinants as well as non-climatic factors that can negate climatic influences. Indeed, there is a scarcity of information on the correlation between climatic variability and malaria transmission risk in Ethiopia in general and in the study area in particular. Therefore, the aim of this study was to determine the level of correlation between meteorological variables and malaria cases. Methods: - Time-series analysis was conducted using data on monthly meteorological variables and monthly total malaria in Jimma town, south west Ethiopia, for the period 2000-2009. All the data were entered and analyzed using SPSS-15 database program. Spearman correlation and linear regression analysis were used to asses association between the variables. Results: - During last ten years (2000-2009), a fluctuating trend of malaria transmission was observed with P.vivax becoming predominant species. Spearman correlation analysis showed that monthly minimum temperature, total rainfall and two measures of relative humidity were positively related with malaria but monthly maximum temperature negatively related. Also regression analysis suggested that monthly minimum (p = 0.008), monthly maximum temperature (p = 0.013) and monthly total rainfall (p = 0.040), at one month lagged effect, were significant meteorological factors for transmission of malaria in the study area. Conclusion: - Malaria incidences in the last decade seem to have a significant association with meteorological variables. In future, prospective and multidisciplinary cooperative research involving researchers from the fields of parasitology, epidemiology, botany, agriculture and

  11. Development of semiclassical molecular dynamics simulation method.

    PubMed

    Nakamura, Hiroki; Nanbu, Shinkoh; Teranishi, Yoshiaki; Ohta, Ayumi

    2016-04-28

    Various quantum mechanical effects such as nonadiabatic transitions, quantum mechanical tunneling and coherence play crucial roles in a variety of chemical and biological systems. In this paper, we propose a method to incorporate tunneling effects into the molecular dynamics (MD) method, which is purely based on classical mechanics. Caustics, which define the boundary between classically allowed and forbidden regions, are detected along classical trajectories and the optimal tunneling path with minimum action is determined by starting from each appropriate caustic. The real phase associated with tunneling can also be estimated. Numerical demonstration with use of a simple collinear chemical reaction O + HCl → OH + Cl is presented in order to help the reader to well comprehend the method proposed here. Generalization to the on-the-fly ab initio version is rather straightforward. By treating the nonadiabatic transitions at conical intersections by the Zhu-Nakamura theory, new semiclassical MD methods can be developed. PMID:27067383

  12. Power transmission cable development for the Space Station Freedom electrical power system

    NASA Technical Reports Server (NTRS)

    Schmitz, Gregory V.; Biess, John J.

    1989-01-01

    Power transmission cable is presently being evaluated under a NASA Lewis Research Center advanced development contract for application in the Space Station Freedom (SSF) electrical power system (EPS). Evaluation testing has been performed by TRW and NASA Lewis Research Center. The results of this development contract are presented. The primary cable design goals are to provide (1) a low characteristic inductance to minimize line voltage drop at 20 kHz, (2) electromagnetic compatibility control of the 20-kHz ac power current, (3) a physical configuration that minimizes ac resistance and (4) release of trapped air for corona-free operation.

  13. Observation of genuine wave vector (k or β) gap in a dynamic transmission line and temporal photonic crystals

    SciTech Connect

    Reyes-Ayona, J. R.; Halevi, P.

    2015-08-17

    By definition, a temporal photonic crystal (TPC) has a permittivity ε(t) that varies periodically with time. We prove that, in the long wavelength limit, a TPC is accurately mimicked by a dynamic transmission line (DTL) having a capacitance (inductance) per unit length equal to ε(t) (μ). Employing a DTL in the microwave region, we measured the photonic band structure, which results to display a genuine wave vector (k or β) gap, in very good agreement with our theoretical model and the equivalent TPC.

  14. Source coding for transmission of reconstructed dynamic geometry: a rate-distortion-complexity analysis of different approaches

    NASA Astrophysics Data System (ADS)

    Mekuria, Rufael N.; Cesar, Pablo; Bulterman, Dick C. A.

    2014-09-01

    Live 3D reconstruction of a human as a 3D mesh with commodity electronics is becoming a reality. Immersive applications (i.e. cloud gaming, tele-presence) benefit from effective transmission of such content over a bandwidth limited link. In this paper we outline different approaches for compressing live reconstructed mesh geometry based on distributing mesh reconstruction functions between sender and receiver. We evaluate rate-performance-complexity of different configurations. First, we investigate 3D mesh compression methods (i.e. dynamic/static) from MPEG-4. Second, we evaluate the option of using octree based point cloud compression and receiver side surface reconstruction.

  15. Transmission or Within-Host Dynamics Driving Pulses of Zoonotic Viruses in Reservoir–Host Populations

    PubMed Central

    Plowright, Raina K.; Peel, Alison J.; Streicker, Daniel G.; Gilbert, Amy T.; McCallum, Hamish; Wood, James; Baker, Michelle L.; Restif, Olivier

    2016-01-01

    Progress in combatting zoonoses that emerge from wildlife is often constrained by limited knowledge of the biology of pathogens within reservoir hosts. We focus on the host–pathogen dynamics of four emerging viruses associated with bats: Hendra, Nipah, Ebola, and Marburg viruses. Spillover of bat infections to humans and domestic animals often coincides with pulses of viral excretion within bat populations, but the mechanisms driving such pulses are unclear. Three hypotheses dominate current research on these emerging bat infections. First, pulses of viral excretion could reflect seasonal epidemic cycles driven by natural variations in population densities and contact rates among hosts. If lifelong immunity follows recovery, viruses may disappear locally but persist globally through migration; in either case, new outbreaks occur once births replenish the susceptible pool. Second, epidemic cycles could be the result of waning immunity within bats, allowing local circulation of viruses through oscillating herd immunity. Third, pulses could be generated by episodic shedding from persistently infected bats through a combination of physiological and ecological factors. The three scenarios can yield similar patterns in epidemiological surveys, but strategies to predict or manage spillover risk resulting from each scenario will be different. We outline an agenda for research on viruses emerging from bats that would allow for differentiation among the scenarios and inform development of evidence-based interventions to limit threats to human and animal health. These concepts and methods are applicable to a wide range of pathogens that affect humans, domestic animals, and wildlife. PMID:27489944

  16. Numerical simulation of the human ear and the dynamic analysis of the middle ear sound transmission

    NASA Astrophysics Data System (ADS)

    Yao, W.; Ma, J.; Huang, X.

    2013-06-01

    Based on the clinical CT of normal right ear, a 3-D ?nite element (FE) model of the human ear consisting of the external ear canal, middle ear(tympanic membrane, ossicular chain, ligaments, tendons), and inner ear (including semicircular canals, vestibular, spiral cochlear)was constructed in this paper. The complicated structures and inner boundary conditions of middle ear were described in this model. Model analysis and acoustic-structure-?uid coupled dynamic frequency response analysis were conducted on the model. The validity of this model was confirmed by comparing the results with published experimental data. The amplitudes and velocities of tympanic membrane and stapes footplate, sound pressure gain across the middle ear, and the cochlear input impedance were derived. Besides, it was concluded that the ear canal can amplify the sound signal in low frequencies.The modes of vibration of middle ear auditory ossicles, oval window and round window have been analysed. This model can well simulate the acoustic behavior with the interaction of external ear, middle ear and inner ear, which can supply more valuable theoretical support for development and improvement of hearing-aid and artificial inner ear.

  17. Trans3D: a free tool for dynamical visualization of EEG activity transmission in the brain.

    PubMed

    Blinowski, Grzegorz; Kamiński, Maciej; Wawer, Dariusz

    2014-08-01

    The problem of functional connectivity in the brain is in the focus of attention nowadays, since it is crucial for understanding information processing in the brain. A large repertoire of measures of connectivity have been devised, some of them being capable of estimating time-varying directed connectivity. Hence, there is a need for a dedicated software tool for visualizing the propagation of electrical activity in the brain. To this aim, the Trans3D application was developed. It is an open access tool based on widely available libraries and supporting both Windows XP/Vista/7(™), Linux and Mac environments. Trans3D can create animations of activity propagation between electrodes/sensors, which can be placed by the user on the scalp/cortex of a 3D model of the head. Various interactive graphic functions for manipulating and visualizing components of the 3D model and input data are available. An application of the Trans3D tool has helped to elucidate the dynamics of the phenomena of information processing in motor and cognitive tasks, which otherwise would have been very difficult to observe. Trans3D is available at: http://www.eeg.pl/. PMID:24967953

  18. Transmission or Within-Host Dynamics Driving Pulses of Zoonotic Viruses in Reservoir-Host Populations.

    PubMed

    Plowright, Raina K; Peel, Alison J; Streicker, Daniel G; Gilbert, Amy T; McCallum, Hamish; Wood, James; Baker, Michelle L; Restif, Olivier

    2016-08-01

    Progress in combatting zoonoses that emerge from wildlife is often constrained by limited knowledge of the biology of pathogens within reservoir hosts. We focus on the host-pathogen dynamics of four emerging viruses associated with bats: Hendra, Nipah, Ebola, and Marburg viruses. Spillover of bat infections to humans and domestic animals often coincides with pulses of viral excretion within bat populations, but the mechanisms driving such pulses are unclear. Three hypotheses dominate current research on these emerging bat infections. First, pulses of viral excretion could reflect seasonal epidemic cycles driven by natural variations in population densities and contact rates among hosts. If lifelong immunity follows recovery, viruses may disappear locally but persist globally through migration; in either case, new outbreaks occur once births replenish the susceptible pool. Second, epidemic cycles could be the result of waning immunity within bats, allowing local circulation of viruses through oscillating herd immunity. Third, pulses could be generated by episodic shedding from persistently infected bats through a combination of physiological and ecological factors. The three scenarios can yield similar patterns in epidemiological surveys, but strategies to predict or manage spillover risk resulting from each scenario will be different. We outline an agenda for research on viruses emerging from bats that would allow for differentiation among the scenarios and inform development of evidence-based interventions to limit threats to human and animal health. These concepts and methods are applicable to a wide range of pathogens that affect humans, domestic animals, and wildlife. PMID:27489944

  19. Development of Novel Methods for the Reduction of Noise and Weight in Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Keith, Theo G., Jr.

    2003-01-01

    Over the 70-year evolution of the helicopter, man's understanding of vibration control has greatly increased. However, in spite of the increased performance, the extent of helicopter vibration problems has not significantly diminished. Crew vibration and noise remains important factors in the design of all current helicopters. With more complex and critical demands being placed on aircrews, it is essential that vibration and noise not impair their performance. A major source of helicopter cabin noise (which has been measured at a sound pressure level of over 100 dB) is the gearbox. Reduction of this noise has been a goal of NASA and the U.S. Army. Gear mesh noise is typically in the frequency range of 1000 to 3000 Hz, a range important for speech. A requirement for U.S. Army/NASA Advanced Rotorcraft Transmission project has been a 10-dB reduction compared to current designs. A combined analytical/experimental effort has been underway, since the end of the 80's, to study effects of design parameters on noise production. The noise generated by the gear mesh can be transmitted to the surrounding media through the bearings that support the gear shaft. Therefore, the use of fluid film bearings instead of rolling element bearings could reduce the transmission noise by 10 dB. In addition, the fluid film bearings that support the gear shaft can change the dynamics of the gear assembly by providing damping to the system and by being softer than rolling element bearings. Wave bearings can attenuate, and filter, the noise generated by a machine component due to the dynamic stiffness and damping coefficients. The attenuation ratio could be as large as 35-40 dB. The noise components at higher frequencies than a synchronous frequency can be almost eliminated.

  20. Stochastic resonance in the synaptic transmission between hair cells and vestibular primary afferents in development.

    PubMed

    Flores, A; Manilla, S; Huidobro, N; De la Torre-Valdovinos, B; Kristeva, R; Mendez-Balbuena, I; Galindo, F; Treviño, M; Manjarrez, E

    2016-05-13

    The stochastic resonance (SR) is a phenomenon of nonlinear systems in which the addition of an intermediate level of noise improves the response of such system. Although SR has been studied in isolated hair cells and in the bullfrog sacculus, the occurrence of this phenomenon in the vestibular system in development is unknown. The purpose of the present study was to explore for the existence of SR via natural mechanical-stimulation in the hair cell-vestibular primary afferent transmission. In vitro experiments were performed on the posterior semicircular canal of the chicken inner ear during development. Our experiments showed that the signal-to-noise ratio of the afferent multiunit activity from E15 to P5 stages of development exhibited the SR phenomenon, which was characterized by an inverted U-like response as a function of the input noise level. The inverted U-like graphs of SR acquired their higher amplitude after the post-hatching stage of development. Blockage of the synaptic transmission with selective antagonists of the NMDA and AMPA/Kainate receptors abolished the SR of the afferent multiunit activity. Furthermore, computer simulations on a model of the hair cell - primary afferent synapse qualitatively reproduced this SR behavior and provided a possible explanation of how and where the SR could occur. These results demonstrate that a particular level of mechanical noise on the semicircular canals can improve the performance of the vestibular system in their peripheral sensory processing even during embryonic stages of development. PMID:26926966

  1. Understanding the effects of different HIV transmission models in individual-based microsimulation of HIV epidemic dynamics in people who inject drugs.

    PubMed

    Monteiro, J F G; Escudero, D J; Weinreb, C; Flanigan, T; Galea, S; Friedman, S R; Marshall, B D L

    2016-06-01

    We investigated how different models of HIV transmission, and assumptions regarding the distribution of unprotected sex and syringe-sharing events ('risk acts'), affect quantitative understanding of HIV transmission process in people who inject drugs (PWID). The individual-based model simulated HIV transmission in a dynamic sexual and injecting network representing New York City. We constructed four HIV transmission models: model 1, constant probabilities; model 2, random number of sexual and parenteral acts; model 3, viral load individual assigned; and model 4, two groups of partnerships (low and high risk). Overall, models with less heterogeneity were more sensitive to changes in numbers risk acts, producing HIV incidence up to four times higher than that empirically observed. Although all models overestimated HIV incidence, micro-simulations with greater heterogeneity in the HIV transmission modelling process produced more robust results and better reproduced empirical epidemic dynamics. PMID:26753627

  2. Analytical study of dynamics of matter-wave solitons in lossless nonlinear discrete bi-inductance transmission lines

    NASA Astrophysics Data System (ADS)

    Kengne, E.; Lakhssassi, A.

    2015-03-01

    We consider a lossless one-dimensional nonlinear discrete bi-inductance electrical transmission line made of N identical unit cells. When lattice effects are considered, we use the reductive perturbation method in the semidiscrete limit to show that the dynamics of modulated waves can be modeled by the classical nonlinear Schrödinger (CNLS) equation, which describes the modulational instability and the propagation of bright and dark solitons on a continuous-wave background. Our theoretical analysis based on the CNLS equation predicts either two or four frequency regions with different behavior concerning the modulational instability of a plane wave. With the help of the analytical solutions of the CNLS equation, we investigate analytically the effects of the linear capacitance CS on the dynamics of matter-wave solitons in the network. Our results reveal that the linear parameter CS can be used to manipulate the motion of bright, dark, and kink soliton in the network.

  3. Analytical study of dynamics of matter-wave solitons in lossless nonlinear discrete bi-inductance transmission lines.

    PubMed

    Kengne, E; Lakhssassi, A

    2015-03-01

    We consider a lossless one-dimensional nonlinear discrete bi-inductance electrical transmission line made of N identical unit cells. When lattice effects are considered, we use the reductive perturbation method in the semidiscrete limit to show that the dynamics of modulated waves can be modeled by the classical nonlinear Schrödinger (CNLS) equation, which describes the modulational instability and the propagation of bright and dark solitons on a continuous-wave background. Our theoretical analysis based on the CNLS equation predicts either two or four frequency regions with different behavior concerning the modulational instability of a plane wave. With the help of the analytical solutions of the CNLS equation, we investigate analytically the effects of the linear capacitance CS on the dynamics of matter-wave solitons in the network. Our results reveal that the linear parameter CS can be used to manipulate the motion of bright, dark, and kink soliton in the network. PMID:25871172

  4. A Class of Tricyclic Compounds Blocking Malaria Parasite Oocyst Development and Transmission

    PubMed Central

    Eastman, Richard T.; Pattaradilokrat, Sittiporn; Raj, Dipak K.; Dixit, Saurabh; Deng, Bingbing; Miura, Kazutoyo; Yuan, Jing; Tanaka, Takeshi Q.; Johnson, Ronald L.; Jiang, Hongying; Huang, Ruili; Williamson, Kim C.; Lambert, Lynn E.; Long, Carole; Austin, Christopher P.; Wu, Yimin

    2013-01-01

    Malaria is a deadly infectious disease in many tropical and subtropical countries. Previous efforts to eradicate malaria have failed, largely due to the emergence of drug-resistant parasites, insecticide-resistant mosquitoes and, in particular, the lack of drugs or vaccines to block parasite transmission. ATP-binding cassette (ABC) transporters are known to play a role in drug transport, metabolism, and resistance in many organisms, including malaria parasites. To investigate whether a Plasmodium falciparum ABC transporter (Pf14_0244 or PfABCG2) modulates parasite susceptibility to chemical compounds or plays a role in drug resistance, we disrupted the gene encoding PfABCG2, screened the recombinant and the wild-type 3D7 parasites against a library containing 2,816 drugs approved for human or animal use, and identified an antihistamine (ketotifen) that became less active against the PfABCG2-disrupted parasite in culture. In addition to some activity against asexual stages and gametocytes, ketotifen was highly potent in blocking oocyst development of P. falciparum and the rodent parasite Plasmodium yoelii in mosquitoes. Tests of structurally related tricyclic compounds identified additional compounds with similar activities in inhibiting transmission. Additionally, ketotifen appeared to have some activity against relapse of Plasmodium cynomolgi infection in rhesus monkeys. Further clinical evaluation of ketotifen and related compounds, including synthetic new derivatives, in blocking malaria transmission may provide new weapons for the current effort of malaria eradication. PMID:23129054

  5. Dynamics of a Delayed Model for the Transmission of Malicious Objects in Computer Network

    PubMed Central

    Yang, Huizhong

    2014-01-01

    An SEIQRS model for the transmission of malicious objects in computer network with two delays is investigated in this paper. We show that possible combination of the two delays can affect the stability of the model and make the model bifurcate periodic solutions under some certain conditions. For further investigation, properties of the periodic solutions are studied by using the normal form method and center manifold theory. Finally, some numerical simulations are given to justify the theoretical results. PMID:25147837

  6. Dynamics of a delayed model for the transmission of malicious objects in computer network.

    PubMed

    Zhang, Zizhen; Yang, Huizhong

    2014-01-01

    An SEIQRS model for the transmission of malicious objects in computer network with two delays is investigated in this paper. We show that possible combination of the two delays can affect the stability of the model and make the model bifurcate periodic solutions under some certain conditions. For further investigation, properties of the periodic solutions are studied by using the normal form method and center manifold theory. Finally, some numerical simulations are given to justify the theoretical results. PMID:25147837

  7. Host genetics determine susceptibility to avian influenza infection and transmission dynamics.

    PubMed

    Ruiz-Hernandez, Raul; Mwangi, William; Peroval, Marylene; Sadeyen, Jean-Remy; Ascough, Stephanie; Balkissoon, Devanand; Staines, Karen; Boyd, Amy; McCauley, John; Smith, Adrian; Butter, Colin

    2016-01-01

    Host-genetic control of influenza virus infection has been the object of little attention. In this study we determined that two inbred lines of chicken differing in their genetic background , Lines 0 and C-B12, were respectively relatively resistant and susceptible to infection with the low pathogenicity influenza virus A/Turkey/England/647/77 as defined by substantial differences in viral shedding trajectories. Resistant birds, although infected, were unable to transmit virus to contact birds, as ultimately only the presence of a sustained cloacal shedding (and not oropharyngeal shedding) was critical for transmission. Restriction of within-bird transmission of virus occurred in the resistant line, with intra-nares or cloacal infection resulting in only local shedding and failing to transmit fully through the gastro-intestinal-pulmonary tract. Resistance to infection was independent of adaptive immune responses, including the expansion of specific IFNγ secreting cells or production of influenza-specific antibody. Genetic resistance to a novel H9N2 virus was less robust, though significant differences between host genotypes were still clearly evident. The existence of host-genetic determination of the outcome of influenza infection offers tools for the further dissection of this regulation and also for understanding the mechanisms of influenza transmission within and between birds. PMID:27279280

  8. Host genetics determine susceptibility to avian influenza infection and transmission dynamics

    PubMed Central

    Ruiz-Hernandez, Raul; Mwangi, William; Peroval, Marylene; Sadeyen, Jean-Remy; Ascough, Stephanie; Balkissoon, Devanand; Staines, Karen; Boyd, Amy; McCauley, John; Smith, Adrian; Butter, Colin

    2016-01-01

    Host-genetic control of influenza virus infection has been the object of little attention. In this study we determined that two inbred lines of chicken differing in their genetic background , Lines 0 and C-B12, were respectively relatively resistant and susceptible to infection with the low pathogenicity influenza virus A/Turkey/England/647/77 as defined by substantial differences in viral shedding trajectories. Resistant birds, although infected, were unable to transmit virus to contact birds, as ultimately only the presence of a sustained cloacal shedding (and not oropharyngeal shedding) was critical for transmission. Restriction of within-bird transmission of virus occurred in the resistant line, with intra-nares or cloacal infection resulting in only local shedding and failing to transmit fully through the gastro-intestinal-pulmonary tract. Resistance to infection was independent of adaptive immune responses, including the expansion of specific IFNγ secreting cells or production of influenza-specific antibody. Genetic resistance to a novel H9N2 virus was less robust, though significant differences between host genotypes were still clearly evident. The existence of host-genetic determination of the outcome of influenza infection offers tools for the further dissection of this regulation and also for understanding the mechanisms of influenza transmission within and between birds. PMID:27279280

  9. Time-Scaled Evolutionary Analysis of the Transmission and Antibiotic Resistance Dynamics of Staphylococcus aureus Clonal Complex 398

    PubMed Central

    Gibbons, C. L.; McAdam, P. R.; van Bunnik, B. A. D.; Girvan, E. K.; Edwards, G. F.; Fitzgerald, J. R.; Woolhouse, M. E. J.

    2014-01-01

    Staphylococcus aureus clonal complex 398 (CC398) is associated with disease in humans and livestock, and its origins and transmission have generated considerable interest. We performed a time-scaled phylogenetic analysis of CC398, including sequenced isolates from the United Kingdom (Scotland), along with publicly available genomes. Using state-of-the-art methods for mapping traits onto phylogenies, we quantified transitions between host species to identify sink and source populations for CC398 and employed a novel approach to investigate the gain and loss of antibiotic resistance in CC398 over time. We identified distinct human- and livestock-associated CC398 clades and observed multiple transmissions of CC398 from livestock to humans and between countries, lending quantitative support to previous reports. Of note, we identified a subclade within the livestock-associated clade comprised of isolates from hospital environments and newborn babies, suggesting that livestock-associated CC398 is capable of onward transmission in hospitals. In addition, our analysis revealed significant differences in the dynamics of resistance to methicillin and tetracycline related to contrasting historical patterns of antibiotic usage between the livestock industry and human medicine. We also identified significant differences in patterns of gain and loss of different tetracycline resistance determinants, which we ascribe to epistatic interactions between the resistance genes and/or differences in the modes of inheritance of the resistance determinants. PMID:25239891

  10. Transmission Dynamics, Border Entry Screening, and School Holidays during the 2009 Influenza A (H1N1) Pandemic, China

    PubMed Central

    Yu, Hongjie; Cauchemez, Simon; Donnelly, Christl A.; Zhou, Lei; Feng, Luzhao; Xiang, Nijuan; Zheng, Jiandong; Ye, Min; Huai, Yang; Liao, Qiaohong; Peng, Zhibin; Feng, Yunxia; Jiang, Hui; Yang, Weizhong; Wang, Yu; Feng, Zijian

    2012-01-01

    Pandemic influenza A (H1N1) 2009 virus spread rapidly around the world in 2009. We used multiple data sources from surveillance systems and specific investigations to characterize the transmission patterns of this virus in China during May–November 2009 and analyze the effectiveness of border entry screening and holiday-related school closures on transmission. In China, age distribution and transmission dynamic characteristics were similar to those in Northern Hemisphere temperate countries. The epidemic was focused in children, with an effective reproduction number of ≈1.2–1.3. The 8 days of national holidays in October reduced the effective reproduction number by 37% (95% credible interval 28%–45%) and increased underreporting by ≈20%–30%. Border entry screening detected at most 37% of international travel–related cases, with most (89%) persons identified as having fever at time of entry. These findings suggest that border entry screening was unlikely to have delayed spread in China by >4 days. PMID:22515989

  11. Time-Scaled Evolutionary Analysis of the Transmission and Antibiotic Resistance Dynamics of Staphylococcus aureus Clonal Complex 398.

    PubMed

    Ward, M J; Gibbons, C L; McAdam, P R; van Bunnik, B A D; Girvan, E K; Edwards, G F; Fitzgerald, J R; Woolhouse, M E J

    2014-12-01

    Staphylococcus aureus clonal complex 398 (CC398) is associated with disease in humans and livestock, and its origins and transmission have generated considerable interest. We performed a time-scaled phylogenetic analysis of CC398, including sequenced isolates from the United Kingdom (Scotland), along with publicly available genomes. Using state-of-the-art methods for mapping traits onto phylogenies, we quantified transitions between host species to identify sink and source populations for CC398 and employed a novel approach to investigate the gain and loss of antibiotic resistance in CC398 over time. We identified distinct human- and livestock-associated CC398 clades and observed multiple transmissions of CC398 from livestock to humans and between countries, lending quantitative support to previous reports. Of note, we identified a subclade within the livestock-associated clade comprised of isolates from hospital environments and newborn babies, suggesting that livestock-associated CC398 is capable of onward transmission in hospitals. In addition, our analysis revealed significant differences in the dynamics of resistance to methicillin and tetracycline related to contrasting historical patterns of antibiotic usage between the livestock industry and human medicine. We also identified significant differences in patterns of gain and loss of different tetracycline resistance determinants, which we ascribe to epistatic interactions between the resistance genes and/or differences in the modes of inheritance of the resistance determinants. PMID:25239891

  12. Development of traveling wave resonator based test bed for high power transmission line component testing

    NASA Astrophysics Data System (ADS)

    Jha, Akhil; Harikrishna, JVS; Ajesh, P.; Anand, Rohit; Trivedi, Rajesh; Mukherjee, Aparajita

    2015-12-01

    India is responsible for delivery of 8+1(prototype) RF sources to ITER Organization. Each RF source will provide 2.5MW of RF power at 2 VSWR in the frequency range of 35 to 65MHz. Eight such RF sources will generate total 20MW of RF power. A large number of high power transmission line components are required for connecting various stages of RF source. To test these passive transmission line components at high power, prior to connecting with RF source system, a test facility is required. India is developing a 3MW test facility based on the concept of Traveling Wave Resonator (TWR) for testing of transmission line components. TWR is basically a ring resonator which will build high power under certain operation condition at resonant frequency (˜55MHz in this case). In TWR, power is fed to the ring via a directional coupler continuously which leads to development of high circulating power in the ring. The voltage and current magnitude inside the ring increases with the increasing circulating power. Detailed RF simulation and design of the TWR test bed has been done using high frequency simulator Microwave Studio (MWS). Calculations done for the ring gain, transmission loss, resonance frequency etc. and are verified with the simulation results. Concept validated using 3-1/8 inch prototype TWR test bed, where experiments were carried out with a ˜10dB (λ/4 coupled) coupler to feed the ring. Ring gain of ˜13.24dB (˜21times) was achieved with ˜0.17 dB of ring loss. Around 9.2 kW ring power is achieved with an input power of 440W. At present, the 3-1/8inch TWR test bed is being upgraded with a ˜15dB coupler to achieve ring gain ˜19-20dB (˜80-100 times). This concept will be finally adopted for 12inch TWR test bed to achieve 3MW ring power with ˜30-40kW of input power. In this paper, detailed design, simulation, test results out of prototype activity and future plan for establishing MW level transmission line test bed is described.

  13. Dynamic Transmission Economic Evaluation of Infectious Disease Interventions in Low- and Middle-Income Countries: A Systematic Literature Review.

    PubMed

    Drake, Tom L; Devine, Angela; Yeung, Shunmay; Day, Nicholas P J; White, Lisa J; Lubell, Yoel

    2016-02-01

    Economic evaluation using dynamic transmission models is important for capturing the indirect effects of infectious disease interventions. We examine the use of these methods in low- and middle-income countries, where infectious diseases constitute a major burden. This review is comprised of two parts: (1) a summary of dynamic transmission economic evaluations across all disease areas published between 2011 and mid-2014 and (2) an in-depth review of mosquito-borne disease studies focusing on health economic methods and reporting. Studies were identified through a systematic search of the MEDLINE database and supplemented by reference list screening. Fifty-seven studies were eligible for inclusion in the all-disease review. The most common subject disease was HIV/AIDS, followed by malaria. A diverse range of modelling methods, outcome metrics and sensitivity analyses were used, indicating little standardisation. Seventeen studies were included in the mosquito-borne disease review. With notable exceptions, most studies did not employ economic evaluation methods beyond calculating a cost-effectiveness ratio or net benefit. Many did not adhere to health care economic evaluations reporting guidelines, particularly with respect to full model reporting and uncertainty analysis. We present a summary of the state-of-the-art and offer recommendations for improved implementation and reporting of health economic methods in this crossover discipline. PMID:26778620

  14. Dynamic Quality of Service Model for Improving Performance of Multimedia Real-Time Transmission in Industrial Networks

    PubMed Central

    Gopalakrishnan, Ravichandran C.; Karunakaran, Manivannan

    2014-01-01

    Nowadays, quality of service (QoS) is very popular in various research areas like distributed systems, multimedia real-time applications and networking. The requirements of these systems are to satisfy reliability, uptime, security constraints and throughput as well as application specific requirements. The real-time multimedia applications are commonly distributed over the network and meet various time constraints across networks without creating any intervention over control flows. In particular, video compressors make variable bit-rate streams that mismatch the constant-bit-rate channels typically provided by classical real-time protocols, severely reducing the efficiency of network utilization. Thus, it is necessary to enlarge the communication bandwidth to transfer the compressed multimedia streams using Flexible Time Triggered- Enhanced Switched Ethernet (FTT-ESE) protocol. FTT-ESE provides automation to calculate the compression level and change the bandwidth of the stream. This paper focuses on low-latency multimedia transmission over Ethernet with dynamic quality-of-service (QoS) management. This proposed framework deals with a dynamic QoS for multimedia transmission over Ethernet with FTT-ESE protocol. This paper also presents distinct QoS metrics based both on the image quality and network features. Some experiments with recorded and live video streams show the advantages of the proposed framework. To validate the solution we have designed and implemented a simulator based on the Matlab/Simulink, which is a tool to evaluate different network architecture using Simulink blocks. PMID:25170768

  15. Dynamic quality of service model for improving performance of multimedia real-time transmission in industrial networks.

    PubMed

    Gopalakrishnan, Ravichandran C; Karunakaran, Manivannan

    2014-01-01

    Nowadays, quality of service (QoS) is very popular in various research areas like distributed systems, multimedia real-time applications and networking. The requirements of these systems are to satisfy reliability, uptime, security constraints and throughput as well as application specific requirements. The real-time multimedia applications are commonly distributed over the network and meet various time constraints across networks without creating any intervention over control flows. In particular, video compressors make variable bit-rate streams that mismatch the constant-bit-rate channels typically provided by classical real-time protocols, severely reducing the efficiency of network utilization. Thus, it is necessary to enlarge the communication bandwidth to transfer the compressed multimedia streams using Flexible Time Triggered- Enhanced Switched Ethernet (FTT-ESE) protocol. FTT-ESE provides automation to calculate the compression level and change the bandwidth of the stream. This paper focuses on low-latency multimedia transmission over Ethernet with dynamic quality-of-service (QoS) management. This proposed framework deals with a dynamic QoS for multimedia transmission over Ethernet with FTT-ESE protocol. This paper also presents distinct QoS metrics based both on the image quality and network features. Some experiments with recorded and live video streams show the advantages of the proposed framework. To validate the solution we have designed and implemented a simulator based on the Matlab/Simulink, which is a tool to evaluate different network architecture using Simulink blocks. PMID:25170768

  16. Dynamics of Japanese Encephalitis Virus Transmission among Pigs in Northwest Bangladesh and the Potential Impact of Pig Vaccination

    PubMed Central

    Khan, Salah Uddin; Salje, Henrik; Hannan, A.; Islam, Md. Atiqul; Bhuyan, A. A. Mamun; Islam, Md. Ariful; Rahman, M. Ziaur; Nahar, Nazmun; Hossain, M. Jahangir; Luby, Stephen P.; Gurley, Emily S.

    2014-01-01

    Background Japanese encephalitis (JE) virus infection can cause severe disease in humans, resulting in death or permanent neurologic deficits among survivors. Studies indicate that the incidence of JE is high in northwestern Bangladesh. Pigs are amplifying hosts for JE virus (JEV) and a potentially important source of virus in the environment. The objectives of this study were to describe the transmission dynamics of JEV among pigs in northwestern Bangladesh and estimate the potential impact of vaccination to reduce incidence among pigs. Methodology/Principal Findings We conducted a comprehensive census of pigs in three JE endemic districts and tested a sample of them for evidence of previous JEV infection. We built a compartmental model to describe JEV transmission dynamics in this region and to estimate the potential impact of pig vaccination. We identified 11,364 pigs in the study area. Previous JEV infection was identified in 30% of pigs with no spatial differences in the proportion of pigs that were seropositive across the study area. We estimated that JEV infects 20% of susceptible pigs each year and the basic reproductive number among pigs was 1.2. The model suggest that vaccinating 50% of pigs each year resulted in an estimated 82% reduction in annual incidence in pigs. Conclusions/Significance The widespread distribution of historic JEV infection in pigs suggests they may play an important role in virus transmission in this area. Future studies are required to understand the contribution of pig infections to JE risk in humans and the potential impact of pig vaccination on human disease. PMID:25255286

  17. Pandemic H1N1 virus transmission and shedding dynamics in index case households of a prospective Vietnamese cohort☆

    PubMed Central

    Thai, Pham Quang; Mai, Le Quynh; Welkers, Matthijs R.A.; Hang, Nguyen Le Khanh; Thanh, Le Thi; Dung, Vu Tien Viet; Yen, Nguyen Thi Thu; Duong, Tran Nhu; Hoa, Le Nguyen Minh; Thoang, Dang Dinh; Trang, Hoang Thi Huyen; de Jong, Menno D.; Wertheim, Heiman; Hien, Nguyen Tran; Horby, Peter; Fox, Annette

    2014-01-01

    Summary Objectives Influenza household transmission studies are required to guide prevention strategies but most passively recruit index cases that seek healthcare. We investigated A(H1N1)pdm09 transmission in a household-based cohort during 2009. Methods Health-workers visited 270 households weekly, and collected swabs from influenza-like-illness cases. If A(H1N1)pdm09 was RT-PCR-confirmed, all household members had symptoms assessed and swabs collected daily for 10–15 days. Viral RNA was quantified and sequenced and serology performed on pre-pandemic sera. Results Index cases were detected in 20 households containing 81 people. 98.5% lacked A(H1N1)pdm09 neutralizing antibodies in pre-pandemic sera. Eleven (18.6%, 95% CI 10.7–30.4%) of 59 contacts were infected. Virus genetic diversity within households was negligible and less than between households. Index and secondary cases were distributed between mothers, daughters and sons, and had similar virus-RNA shedding and symptom dynamics. Fathers were rarely infected. Five secondary cases (45%) had no apparent symptoms and three shed virus before symptoms. Secondary infection was associated with index case wet cough (OR 1.56, 95% CI 1.22–1.99). Conclusions In this cohort of A(H1N1)pdm09 susceptible persons, virus sequencing was capable of discriminating household from community transmission. Household transmission involved mothers and children but rarely fathers. Asymptomatic or pre-symptomatic shedding was common. PMID:24491598

  18. Development of modulated optical transmission system to determinate the cloud and freezing points in biofuels.

    PubMed

    Jaramillo-Ochoa, Liliana; Ramirez-Gutierrez, Cristian F; Sánchez-Moguel, Alonso; Acosta-Osorio, Andrés; Rodriguez-Garcia, Mario E

    2015-01-01

    This work is focused in the development of a modulated optical transmission system with temperature control to determine the thermal properties of biodiesels such as the cloud and freezing points. This system is able to determine these properties in real time without relying on the operator skills as indicated in the American Society for Testing Materials (ASTM) norms. Thanks to the modulation of the incident laser, the noise of the signal is reduced and two information channels are generated: amplitude and phase. Lasers with different wavelengths can be used in this system but the sample under study must have optical absorption at the wavelength of the laser. PMID:25638112

  19. Development of modulated optical transmission system to determinate the cloud and freezing points in biofuels

    NASA Astrophysics Data System (ADS)

    Jaramillo-Ochoa, Liliana; Ramirez-Gutierrez, Cristian F.; Sánchez-Moguel, Alonso; Acosta-Osorio, Andrés; Rodriguez-Garcia, Mario E.

    2015-01-01

    This work is focused in the development of a modulated optical transmission system with temperature control to determine the thermal properties of biodiesels such as the cloud and freezing points. This system is able to determine these properties in real time without relying on the operator skills as indicated in the American Society for Testing Materials (ASTM) norms. Thanks to the modulation of the incident laser, the noise of the signal is reduced and two information channels are generated: amplitude and phase. Lasers with different wavelengths can be used in this system but the sample under study must have optical absorption at the wavelength of the laser.

  20. The role of neutralizing antibodies for mouse mammary tumor virus transmission and mammary cancer development

    NASA Astrophysics Data System (ADS)

    Finke, Daniela; Luther, Sanjiv A.; Acha-Orbea, Hans

    2003-01-01

    Mouse mammary tumor virus (MMTV) infection establishes chronic germinal centers and a lifelong neutralizing Ab response. We show that removal of the draining lymph node after establishment of the germinal center reaction led to complete loss of neutralizing Abs despite comparable infection levels in peripheral lymphocytes. Importantly, in the absence of neutralization, only the exocrine organs mammary gland, salivary gland, pancreas, and skin showed strikingly increased infection, resulting in accelerated mammary tumor development. Induction of stronger neutralization did not influence chronic infection levels of peripheral lymphoid organs but strongly inhibited mammary gland infection and virus transmission to the next generation. Taken together, we provide evidence that a tight equilibrium in virus neutralization allows limited infection of exocrine organs and controls cancer development in susceptible mouse strains. These experiments show that a strong neutralizing Ab response induced after infection is not able to control lymphoid MMTV infection. Strong neutralization, however, is capable of blocking amplification of mammary gland infection, tumor development, and virus transmission to the next generation. The results also indicate a role of neutralization in natural resistance to MMTV infection.

  1. Modeling the transmission of community-associated methicillin-resistant Staphylococcus aureus: a dynamic agent-based simulation

    PubMed Central

    2014-01-01

    Background Methicillin-resistant Staphylococcus aureus (MRSA) has been a deadly pathogen in healthcare settings since the 1960s, but MRSA epidemiology changed since 1990 with new genetically distinct strain types circulating among previously healthy people outside healthcare settings. Community-associated (CA) MRSA strains primarily cause skin and soft tissue infections, but may also cause life-threatening invasive infections. First seen in Australia and the U.S., it is a growing problem around the world. The U.S. has had the most widespread CA-MRSA epidemic, with strain type USA300 causing the great majority of infections. Individuals with either asymptomatic colonization or infection may transmit CA-MRSA to others, largely by skin-to-skin contact. Control measures have focused on hospital transmission. Limited public health education has focused on care for skin infections. Methods We developed a fine-grained agent-based model for Chicago to identify where to target interventions to reduce CA-MRSA transmission. An agent-based model allows us to represent heterogeneity in population behavior, locations and contact patterns that are highly relevant for CA-MRSA transmission and control. Drawing on nationally representative survey data, the model represents variation in sociodemographics, locations, behaviors, and physical contact patterns. Transmission probabilities are based on a comprehensive literature review. Results Over multiple 10-year runs with one-hour ticks, our model generates temporal and geographic trends in CA-MRSA incidence similar to Chicago from 2001 to 2010. On average, a majority of transmission events occurred in households, and colonized rather than infected agents were the source of the great majority (over 95%) of transmission events. The key findings are that infected people are not the primary source of spread. Rather, the far greater number of colonized individuals must be targeted to reduce transmission. Conclusions Our findings suggest

  2. Genome-Based Infection Tracking Reveals Dynamics of Clostridium difficile Transmission and Disease Recurrence

    PubMed Central

    Kumar, Nitin; Miyajima, Fabio; He, Miao; Roberts, Paul; Swale, Andrew; Ellison, Louise; Pickard, Derek; Smith, Godfrey; Molyneux, Rebecca; Dougan, Gordon; Parkhill, Julian; Wren, Brendan W.; Parry, Christopher M.; Pirmohamed, Munir; Lawley, Trevor D.

    2016-01-01

    Background. Accurate tracking of Clostridium difficile transmission within healthcare settings is key to its containment but is hindered by the lack of discriminatory power of standard genotyping methods. We describe a whole-genome phylogenetic-based method to track the transmission of individual clones in infected hospital patients from the epidemic C. difficile 027/ST1 lineage, and to distinguish between the 2 causes of recurrent disease, relapse (same strain), or reinfection (different strain). Methods. We monitored patients with C. difficile infection in a UK hospital over a 2-year period. We performed whole-genome sequencing and phylogenetic analysis of 108 strains isolated from symptomatic patients. High-resolution phylogeny was integrated with in-hospital transfers and contact data to create an infection network linking individual patients and specific hospital wards. Results. Epidemic C. difficile 027/ST1 caused the majority of infections during our sampling period. Integration of whole-genome single nucleotide polymorphism (SNP) phylogenetic analysis, which accurately discriminated between 27 distinct SNP genotypes, with patient movement and contact data identified 32 plausible transmission events, including ward-based contamination (66%) or direct donor–recipient contact (34%). Highly contagious donors were identified who contributed to the persistence of clones within distinct hospital wards and the spread of clones between wards, especially in areas of intense turnover. Recurrent cases were identified between 4 and 26 weeks, highlighting the limitation of the standard <8-week cutoff used for patient diagnosis and management. Conclusions. Genome-based infection tracking to monitor the persistence and spread of C. difficile within healthcare facilities could inform infection control and patient management. PMID:26683317

  3. A generating function approach to HIV transmission with dynamic contact rates

    DOE PAGESBeta

    Romero-Severson, Ethan O.; Meadors, Grant D.; Volz, Erik M.

    2014-04-24

    The basic reproduction number, R0, is often defined as the average number of infections generated by a newly infected individual in a fully susceptible population. The interpretation, meaning, and derivation of R0 are controversial. However, in the context of mean field models, R0 demarcates the epidemic threshold below which the infected population approaches zero in the limit of time. In this manner, R0 has been proposed as a method for understanding the relative impact of public health interventions with respect to disease eliminations from a theoretical perspective. The use of R0 is made more complex by both the strong dependencymore » of R0 on the model form and the stochastic nature of transmission. A common assumption in models of HIV transmission that have closed form expressions for R0 is that a single individual’s behavior is constant over time. For this research, we derive expressions for both R0 and probability of an epidemic in a finite population under the assumption that people periodically change their sexual behavior over time. We illustrate the use of generating functions as a general framework to model the effects of potentially complex assumptions on the number of transmissions generated by a newly infected person in a susceptible population. In conclusion, we find that the relationship between the probability of an epidemic and R0 is not straightforward, but, that as the rate of change in sexual behavior increases both R0 and the probability of an epidemic also decrease.« less

  4. A generating function approach to HIV transmission with dynamic contact rates

    SciTech Connect

    Romero-Severson, Ethan O.; Meadors, Grant D.; Volz, Erik M.

    2014-04-24

    The basic reproduction number, R0, is often defined as the average number of infections generated by a newly infected individual in a fully susceptible population. The interpretation, meaning, and derivation of R0 are controversial. However, in the context of mean field models, R0 demarcates the epidemic threshold below which the infected population approaches zero in the limit of time. In this manner, R0 has been proposed as a method for understanding the relative impact of public health interventions with respect to disease eliminations from a theoretical perspective. The use of R0 is made more complex by both the strong dependency of R0 on the model form and the stochastic nature of transmission. A common assumption in models of HIV transmission that have closed form expressions for R0 is that a single individual’s behavior is constant over time. For this research, we derive expressions for both R0 and probability of an epidemic in a finite population under the assumption that people periodically change their sexual behavior over time. We illustrate the use of generating functions as a general framework to model the effects of potentially complex assumptions on the number of transmissions generated by a newly infected person in a susceptible population. In conclusion, we find that the relationship between the probability of an epidemic and R0 is not straightforward, but, that as the rate of change in sexual behavior increases both R0 and the probability of an epidemic also decrease.

  5. Transmission Dynamics of Visceral Leishmaniasis in the Indian Subcontinent – A Systematic Literature Review

    PubMed Central

    Boelaert, Marleen; Matlashewski, Greg; Mondal, Dinesh; Arana, Byron; Kroeger, Axel; Olliaro, Piero

    2016-01-01

    Background As Bangladesh, India and Nepal progress towards visceral leishmaniasis (VL) elimination, it is important to understand the role of asymptomatic Leishmania infection (ALI), VL treatment relapse and post kala-azar dermal leishmaniasis (PKDL) in transmission. Methodology/ Principal Finding We reviewed evidence systematically on ALI, relapse and PKDL. We searched multiple databases to include studies on burden, risk factors, biomarkers, natural history, and infectiveness of ALI, PKDL and relapse. After screening 292 papers, 98 were included covering the years 1942 through 2016. ALI, PKDL and relapse studies lacked a reference standard and appropriate biomarker. The prevalence of ALI was 4–17-fold that of VL. The risk of ALI was higher in VL case contacts. Most infections remained asymptomatic or resolved spontaneously. The proportion of ALI that progressed to VL disease within a year was 1.5–23%, and was higher amongst those with high antibody titres. The natural history of PKDL showed variability; 3.8–28.6% had no past history of VL treatment. The infectiveness of PKDL was 32–53%. The risk of VL relapse was higher with HIV co-infection. Modelling studies predicted a range of scenarios. One model predicted VL elimination was unlikely in the long term with early diagnosis. Another model estimated that ALI contributed to 82% of the overall transmission, VL to 10% and PKDL to 8%. Another model predicted that VL cases were the main driver for transmission. Different models predicted VL elimination if the sandfly density was reduced by 67% by killing the sandfly or by 79% by reducing their breeding sites, or with 4–6y of optimal IRS or 10y of sub-optimal IRS and only in low endemic setting. Conclusion/ Significance There is a need for xenodiagnostic and longitudinal studies to understand the potential of ALI and PKDL as reservoirs of infection. PMID:27490264

  6. Dynamical Analysis of an SEIT Epidemic Model with Application to Ebola Virus Transmission in Guinea

    PubMed Central

    Li, Zhiming; Teng, Zhidong; Feng, Xiaomei; Li, Yingke; Zhang, Huiguo

    2015-01-01

    In order to investigate the transmission mechanism of the infectious individual with Ebola virus, we establish an SEIT (susceptible, exposed in the latent period, infectious, and treated/recovery) epidemic model. The basic reproduction number is defined. The mathematical analysis on the existence and stability of the disease-free equilibrium and endemic equilibrium is given. As the applications of the model, we use the recognized infectious and death cases in Guinea to estimate parameters of the model by the least square method. With suitable parameter values, we obtain the estimated value of the basic reproduction number and analyze the sensitivity and uncertainty property by partial rank correlation coefficients. PMID:26246849

  7. Modeling Transmission Dynamics and Control of Vector-Borne Neglected Tropical Diseases

    PubMed Central

    Luz, Paula M.; Struchiner, Claudio J.; Galvani, Alison P.

    2010-01-01

    Neglected tropical diseases affect more than one billion people worldwide. The populations most impacted by such diseases are typically the most resource-limited. Mathematical modeling of disease transmission and cost-effectiveness analyses can play a central role in maximizing the utility of limited resources for neglected tropical diseases. We review the contributions that mathematical modeling has made to optimizing intervention strategies of vector-borne neglected diseases. We propose directions forward in the modeling of these diseases, including integrating new knowledge of vector and pathogen ecology, incorporating evolutionary responses to interventions, and expanding the scope of sensitivity analysis in order to achieve robust results. PMID:21049062

  8. Transmission dynamics of Tasmanian devil facial tumor disease may lead to disease-induced extinction.

    PubMed

    McCallum, Hamish; Jones, Menna; Hawkins, Clare; Hamede, Rodrigo; Lachish, Shelly; Sinn, David L; Beeton, Nick; Lazenby, Billie

    2009-12-01

    Most pathogens threatening to cause extinction of a host species are maintained on one or more reservoir hosts, in addition to the species that is threatened by disease. Further, most conventional host-pathogen theory assumes that transmission is related to host density, and therefore a pathogen should become extinct before its sole host. Tasmanian devil facial tumor disease is a recently emerged infectious cancer that has led to massive population declines and grave concerns for the future persistence of this largest surviving marsupial carnivore. Here we report the results of mark-recapture studies at six sites and use these data to estimate epidemiological parameters critical to both accurately assessing the risk of extinction from this disease and effectively managing this disease threat. Three sites were monitored from before or close to the time of disease arrival, and at three others disease was well established when trapping began, in one site for at least 10 years. We found no evidence for sex-specific differences in disease prevalence and little evidence of consistent seasonal variation in the force of infection. At all sites, the disease was maintained at high levels of prevalence (>50% in 2-3-year-old animals), despite causing major population declines. We also provide the first estimates of the basic reproductive rate R0 for this disease. Using a simple age-structured deterministic model, we show that our results are not consistent with transmission being proportional to the density of infected hosts but are consistent with frequency-dependent transmission. This conclusion is further supported by the observation that local disease prevalence in 2-3-year-olds still exceeds 50% at a site where population density has been reduced by up to 90% in the past 12 years. These findings lend considerable weight to concerns that this host-specific pathogen will cause the extinction of the Tasmanian devil. Our study highlights the importance of rapidly implementing

  9. Malaria vectors and transmission dynamics in Goulmoun, a rural city in south-western Chad

    PubMed Central

    2009-01-01

    Background Knowledge of some baseline entomological data such as Entomological Inoculation Rates (EIR) is crucially needed to assess the epidemiological impact of malaria control activities directed either against parasites or vectors. In Chad, most published surveys date back to the 1960's. In this study, anopheline species composition and their relation to malaria transmission were investigated in a dry Sudanian savannas area of Chad. Methods A 12-month longitudinal survey was conducted in the irrigated rice-fields area of Goulmoun in south western Chad. Human landing catches were performed each month from July 2006 to June 2007 in three compounds (indoors and outdoors) and pyrethrum spray collections were conducted in July, August and October 2006 in 10 randomly selected rooms. Mosquitoes belonging to the Anopheles gambiae complex and to the An. funestus group were identified by molecular diagnostic tools. Plasmodium falciparum infection and blood meal sources were detected by ELISA. Results Nine anopheline species were collected by the two sampling methods. The most aggressive species were An. arabiensis (51 bites/human/night), An. pharoensis (12.5 b/h/n), An. funestus (1.5 b/h/n) and An. ziemanni (1.3 b/h/n). The circumsporozoite protein rate was 1.4% for An. arabiensis, 1.4% for An. funestus, 0.8% for An. pharoensis and 0.5% for An. ziemanni. Malaria transmission is seasonal, lasting from April to December. However, more than 80% of the total EIR was concentrated in the period from August to October. The overall annual EIR was estimated at 311 bites of infected anophelines/human/year, contributed mostly by An. arabiensis (84.5%) and An. pharoensis (12.2%). Anopheles funestus and An. ziemanni played a minor role. Parasite inoculation occurred mostly after 22:00 hours but around 20% of bites of infected anophelines were distributed earlier in the evening. Conclusion The present study revealed the implication of An. pharoensis in malaria transmission in the

  10. Dynamical Analysis of an SEIT Epidemic Model with Application to Ebola Virus Transmission in Guinea.

    PubMed

    Li, Zhiming; Teng, Zhidong; Feng, Xiaomei; Li, Yingke; Zhang, Huiguo

    2015-01-01

    In order to investigate the transmission mechanism of the infectious individual with Ebola virus, we establish an SEIT (susceptible, exposed in the latent period, infectious, and treated/recovery) epidemic model. The basic reproduction number is defined. The mathematical analysis on the existence and stability of the disease-free equilibrium and endemic equilibrium is given. As the applications of the model, we use the recognized infectious and death cases in Guinea to estimate parameters of the model by the least square method. With suitable parameter values, we obtain the estimated value of the basic reproduction number and analyze the sensitivity and uncertainty property by partial rank correlation coefficients. PMID:26246849

  11. Vertical transmission of Zika virus targeting the radial glial cells affects cortex development of offspring mice.

    PubMed

    Wu, Kong-Yan; Zuo, Guo-Long; Li, Xiao-Feng; Ye, Qing; Deng, Yong-Qiang; Huang, Xing-Yao; Cao, Wu-Chun; Qin, Cheng-Feng; Luo, Zhen-Ge

    2016-06-01

    The recent Zika virus (ZIKV) epidemic in Latin America coincided with a marked increase in microcephaly in newborns. However, the causal link between maternal ZIKV infection and malformation of the fetal brain has not been firmly established. Here we show a vertical transmission of ZIKV in mice and a marked effect on fetal brain development. We found that intraperitoneal (i.p.) injection of a contemporary ZIKV strain in pregnant mice led to the infection of radial glia cells (RGs) of dorsal ventricular zone of the fetuses, the primary neural progenitors responsible for cortex development, and caused a marked reduction of these cortex founder cells in the fetuses. Interestingly, the infected fetal mice exhibited a reduced cavity of lateral ventricles and a discernable decrease in surface areas of the cortex. This study thus supports the conclusion that vertically transmitted ZIKV affects fetal brain development and provides a valuable animal model for the evaluation of potential therapeutic or preventative strategies. PMID:27174054

  12. Vertical transmission of Zika virus targeting the radial glial cells affects cortex development of offspring mice

    PubMed Central

    Wu, Kong-Yan; Zuo, Guo-Long; Li, Xiao-Feng; Ye, Qing; Deng, Yong-Qiang; Huang, Xing-Yao; Cao, Wu-Chun; Qin, Cheng-Feng; Luo, Zhen-Ge

    2016-01-01

    The recent Zika virus (ZIKV) epidemic in Latin America coincided with a marked increase in microcephaly in newborns. However, the causal link between maternal ZIKV infection and malformation of the fetal brain has not been firmly established. Here we show a vertical transmission of ZIKV in mice and a marked effect on fetal brain development. We found that intraperitoneal (i.p.) injection of a contemporary ZIKV strain in pregnant mice led to the infection of radial glia cells (RGs) of dorsal ventricular zone of the fetuses, the primary neural progenitors responsible for cortex development, and caused a marked reduction of these cortex founder cells in the fetuses. Interestingly, the infected fetal mice exhibited a reduced cavity of lateral ventricles and a discernable decrease in surface areas of the cortex. This study thus supports the conclusion that vertically transmitted ZIKV affects fetal brain development and provides a valuable animal model for the evaluation of potential therapeutic or preventative strategies. PMID:27174054

  13. Molecular characterization of rabies virus isolates from Mexico: implications for transmission dynamics and human risk.

    PubMed

    De Mattos, C C; De Mattos, C A; Loza-Rubio, E; Aguilar-Setién, A; Orciari, L A; Smith, J S

    1999-10-01

    Twenty-eight samples from humans and domestic and wild animals collected in Mexico between 1990 and 1995 were characterized by using anti-nucleoprotein monoclonal antibodies and limited sequence analysis of the nucleoprotein gene. The variants of rabies viruses identified in these samples were compared with other isolates from Mexico and the rest of the Americas to establish epidemiologic links between cases and outbreaks and to increase the understanding of rabies epidemiology in the Western Hemisphere. Antigenic and genetic diversity was found in all samples from dogs and dog-related cases, suggesting a long-term endemic situation with multiple, independent cycles of virus transmission. Two isolates from bobcats were antigenically and genetically homologous to the rabies variant circulating in the Arizona gray fox population, indicating a wider distribution of this variant than previously reported. Rabies isolates from skunks were unrelated to any variant analyzed in this study and represent a previously unrecognized cycle of rabies transmission in skunks in Baja California Sur. Two antigenic and genetic variants co-circulating in southern and eastern Mexico were found in viruses obtained from cases epidemiologically related to vampire bats. These results serve as a baseline for the better understanding of the molecular epidemiology of rabies in Mexico. PMID:10548293

  14. Disease dynamics of Porites bleaching with tissue loss: prevalence, virulence, transmission, and environmental drivers.

    PubMed

    Sudek, M; Williams, G J; Runyon, C; Aeby, G S; Davy, S K

    2015-02-10

    The prevalence, number of species affected, and geographical extent of coral diseases have been increasing worldwide. We present ecological data on the coral disease Porites bleaching with tissue loss (PBTL) from Kaneohe Bay, Oahu (Hawaii, USA), affecting P. compressa. This disease is prevalent throughout the year, although it shows spatio-temporal variability with peak prevalence during the warmer summer months. Temporal variability in disease prevalence showed a strong positive relationship with elevated water temperature. Spatially, PBTL prevalence peaked in clearer waters (lower turbidity) with higher water flow and higher densities of parrotfish, together explaining approximately 26% of the spatial variability in PBTL prevalence. However, the relatively poor performance of the spatial model suggests that other, unmeasured factors may be more important in driving spatial prevalence. PBTL was not transmissible through direct contact or the water column in controlled aquaria experiments, suggesting that this disease may not be caused by a pathogen, is not highly infectious, or perhaps requires a vector for transmission. In general, PBTL results in partial tissue mortality of affected colonies; on average, one-third of the tissue is lost. This disease can affect the same colonies repeatedly, suggesting a potential for progressive damage which could cause increased tissue loss over time. P. compressa is the main framework-building species in Kaneohe Bay; PBTL therefore has the potential to negatively impact the structure of the reefs at this location. PMID:25667337

  15. Fast data transmission in dynamic data acquisition system for plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Byszuk, Adrian; Poźniak, Krzysztof; Zabołotny, Wojciech M.; Kasprowicz, Grzegorz; Wojeński, Andrzej; Cieszewski, Radosław; Juszczyk, Bartłomiej; Kolasiński, Piotr; Zienkiewicz, Paweł; Chernyshova, Maryna; Czarski, Tomasz

    2014-11-01

    This paper describes architecture of a new data acquisition system (DAQ) targeted mainly at plasma diagnostic experiments. Modular architecture, in combination with selected hardware components, allows for straightforward reconfiguration of the whole system, both offline and online. Main emphasis will be put into the implementation of data transmission subsystem in said system. One of the biggest advantages of described system is modular architecture with well defined boundaries between main components: analog frontend (AFE), digital backplane and acquisition/control software. Usage of a FPGA chips allows for a high flexibility in design of analog frontends, including ADC <--> FPGA interface. Data transmission between backplane boards and user software was accomplished with the use of industry-standard PCI Express (PCIe) technology. PCIe implementation includes both FPGA firmware and Linux device driver. High flexibility of PCIe connections was accomplished due to use of configurable PCIe switch. Whenever it's possible, described DAQ system tries to make use of standard off-the-shelf (OTF) components, including typical x86 CPU & motherboard (acting as PCIe controller) and cabling.

  16. Communication Range Dynamics and Performance Analysis for a Self-Adaptive Transmission Power Controller.

    PubMed

    Lucas Martínez, Néstor; Martínez Ortega, José-Fernán; Hernández Díaz, Vicente; Del Toro Matamoros, Raúl M

    2016-01-01

    The deployment of the nodes in a Wireless Sensor and Actuator Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. Additionally, when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects and, of course, radio irregularities. A control-based self-adaptive system is a typical solution to improve the energy consumption while keeping good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value. PMID:27187397

  17. Communication Range Dynamics and Performance Analysis for a Self-Adaptive Transmission Power Controller †

    PubMed Central

    Lucas Martínez, Néstor; Martínez Ortega, José-Fernán; Hernández Díaz, Vicente; del Toro Matamoros, Raúl M.

    2016-01-01

    The deployment of the nodes in a Wireless Sensor and Actuator Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. Additionally, when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects and, of course, radio irregularities. A control-based self-adaptive system is a typical solution to improve the energy consumption while keeping good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value. PMID:27187397

  18. Genetic diversity and evolutionary insights of respiratory syncytial virus A ON1 genotype: global and local transmission dynamics

    PubMed Central

    Duvvuri, Venkata R.; Granados, Andrea; Rosenfeld, Paul; Bahl, Justin; Eshaghi, Alireza; Gubbay, Jonathan B.

    2015-01-01

    Human respiratory syncytial virus (RSV) A ON1 genotype, first detected in 2010 in Ontario, Canada, has been documented in 21 countries to date. This study investigated persistence and transmission dynamics of ON1 by grouping 406 randomly selected RSV-positive specimens submitted to Public Health Ontario from August 2011 to August 2012; RSV-A-positive specimens were genotyped. We identified 370 RSV-A (181 NA1, 135 NA2, 51 ON1 3 GA5) and 36 RSV-B positive specimens. We aligned time-stamped second hypervariable region (330 bp) of G-gene sequence data (global, n = 483; and Ontario, n = 60) to evaluate transmission dynamics. Global data suggests that the most recent common ancestor of ON1 emerged during the 2008–2009 season. Mean evolutionary rate of the global ON1 was 4.10 × 10−3 substitutions/site/year (95% BCI 3.1–5.0 × 10−3), not significantly different to that of Ontario ON1. The estimated mean reproductive number (R0 = ∼ 1.01) from global and Ontario sequences showed no significant difference and implies stability among global RSV-A ON1. This study suggests that local epidemics exhibit similar underlying evolutionary and epidemiological dynamics to that of the persistent global RSV-A ON1 population. These findings underscore the importance of continual molecular surveillance of RSV in order to gain a better understanding of epidemics. PMID:26420660

  19. LGI1 acts presynaptically to regulate excitatory synaptic transmission during early postnatal development.

    PubMed

    Boillot, Morgane; Lee, Chun-Yao; Allene, Camille; Leguern, Eric; Baulac, Stéphanie; Rouach, Nathalie

    2016-01-01

    The secreted leucine-rich glioma inactivated 1 (LGI1) protein is an important actor for human seizures of both genetic and autoimmune etiology: mutations in LGI1 cause inherited temporal lobe epilepsy, while LGI1 is involved in antibody-mediated encephalitis. Remarkably, Lgi1-deficient (Lgi1(-/-)) mice recapitulate the epileptic disorder and display early-onset spontaneous seizures. To understand how Lgi1-deficiency leads to seizures during postnatal development, we here investigated the early functional and structural defects occurring before seizure onset in Lgi1(-/-) mice. We found an increased excitatory synaptic transmission in hippocampal slices from Lgi1(-/-) mice. No structural alteration in the morphology of pyramidal cell dendrites and synapses was observed at this stage, indicating that Lgi1-deficiency is unlikely to trigger early developmental abnormalities. Consistent with the presynaptic subcellular localization of the protein, Lgi1-deficiency caused presynaptic defects, with no alteration in postsynaptic AMPA receptor activity in Lgi1-/- pyramidal cells before seizure onset. Presynaptic dysfunction led to increased synaptic glutamate levels, which were associated with hyperexcitable neuronal networks. Altogether, these data show that Lgi1 acts presynaptically as a negative modulator of excitatory synaptic transmission during early postnatal development. We therefore here reveal that increased presynaptic glutamate release is a key early event resulting from Lgi1-deficiency, which likely contributes to epileptogenesis. PMID:26878798

  20. LGI1 acts presynaptically to regulate excitatory synaptic transmission during early postnatal development

    PubMed Central

    Boillot, Morgane; Lee, Chun-Yao; Allene, Camille; Leguern, Eric; Baulac, Stéphanie; Rouach, Nathalie

    2016-01-01

    The secreted leucine-rich glioma inactivated 1 (LGI1) protein is an important actor for human seizures of both genetic and autoimmune etiology: mutations in LGI1 cause inherited temporal lobe epilepsy, while LGI1 is involved in antibody-mediated encephalitis. Remarkably, Lgi1-deficient (Lgi1−/−) mice recapitulate the epileptic disorder and display early-onset spontaneous seizures. To understand how Lgi1-deficiency leads to seizures during postnatal development, we here investigated the early functional and structural defects occurring before seizure onset in Lgi1−/− mice. We found an increased excitatory synaptic transmission in hippocampal slices from Lgi1−/− mice. No structural alteration in the morphology of pyramidal cell dendrites and synapses was observed at this stage, indicating that Lgi1-deficiency is unlikely to trigger early developmental abnormalities. Consistent with the presynaptic subcellular localization of the protein, Lgi1-deficiency caused presynaptic defects, with no alteration in postsynaptic AMPA receptor activity in Lgi1−/− pyramidal cells before seizure onset. Presynaptic dysfunction led to increased synaptic glutamate levels, which were associated with hyperexcitable neuronal networks. Altogether, these data show that Lgi1 acts presynaptically as a negative modulator of excitatory synaptic transmission during early postnatal development. We therefore here reveal that increased presynaptic glutamate release is a key early event resulting from Lgi1-deficiency, which likely contributes to epileptogenesis. PMID:26878798

  1. Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

    2007-01-01

    Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

  2. Development of lightweight blazed transmission gratings and large-area soft x-ray spectrographs

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2013-09-01

    Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer, comprised of large collecting-area focusing optics with a narrow point spread function, large-area high-resolving power diffraction gratings, and small pixel, order sorting x-ray detectors. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers (AEGIS, AXSIO, SMART-X) promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit related to the detection and characterization of emission and absorption lines, thereby addressing high-priority questions identified in the Astro2010 Decadal Survey "New Worlds New Horizons". We review the current status of CAT grating fabrication, present recent fabrication results, and describe our plans and technology development roadmap for the coming year and beyond.

  3. Noise-driven signal transmission device using molecular dynamics of organic polymers

    NASA Astrophysics Data System (ADS)

    Asakawa, Naoki; Umemura, Koichiro; Fujise, Shinya; Yazawa, Koji; Shimizu, Tadashi; Tansho, Masataka; Kanki, Teruo; Tanaka, Hidekazu

    2014-01-01

    Stochastic threshold devices using a trap-filling transition (TFT) coupled with molecular dynamics in poly(3-alkylthiophene)s were fabricated as potential key devices for noise-driven bioinspired sensors and information processors. This article deals with variable-temperature direct current conductivity and alternating current impedance measurements for vertical-type device elements of Au/regioregular poly(3-decylthiophene) ((RR-P3DT) (thickness: 100 nm)/Au, which show multiple conducting states and quasi-stochastic transitions between these states. Noise measurements indicate the ω-2-type (if VVTFT) power spectral densities, where V and VTFT are an applied voltage and the voltage for TFT, respectively. The noise generation is due to the TFT associated with twist dynamics of π-conjugated polymers near the order-disorder phase transition (ODT). At 298 K, the quasi-stochastic behavior is more noticeable for RR-P3DT than poly(3-hexylthiophene). The quasi-stochastic property is employed to a stochastic one-directional signal transmitting device using optical-electric conversion. The dynamics of ODT for powder samples were also investigated by differential scanning calorimetry measurements and high-resolution solid-state C13 nuclear magnetic resonance spectroscopy, and the correlation of the molecular structure and dynamics with electric properties was discussed.

  4. Noise-driven signal transmission device using molecular dynamics of organic polymers

    NASA Astrophysics Data System (ADS)

    Asakawa, Naoki; Kanki, Teruo; Tanaka, Hidekazu

    2014-03-01

    Stochastic threshold devices using trap-filling transition coupled with molecular dynamics in poly(3-alkyl thiophene)s [P3ATs] were fabricated as potential key devices for noise-driven bio-inspired sensors and infor- mation processors. This article deals with variable-temperature direct current conductivity and alternating current impedance measurements for vertical-type device elements of Au/regioregular poly(3-decylthiophene) [RR-P3DT] (thickness:100nm)/Au, which show multiple conducting states and quasi-stochastic transitions between these states. Noise measurements indicate the ω-2-type (if V < VTFT = 10V) and ω-1-type (if V > VTFT) power spectral densities, where V and VTFT are an applied voltage and the voltage for trap-filling transition(TFT),respectively. The noise generation is due to TFT that associated with twist dynamics of π-conjugated polymers near the order-disorder phase transition. At 298K, the quasi-stochastic behavior is more noticeable for RR-P3DT than poly(3-hexylthiophene) [RR-P3HT]. The dynamics of the order-disorder phase transition (ODT) for powder samples were also investigated by differential scanning calorimetry (DSC) measurements and high-resolution solid-state C NMR spectroscopy, and the correlation of molecular structure and dynamics with electric properties was discussed.

  5. Seasonal Population Dynamics of Draeculacephala minerva (Hemiptera: Cicadellidae) and Transmission Efficiency of Xylella fastidiosa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The green sharpshooter, Draeculacephala minerva Ball, is a very common and often abundant grass-feeding leafhopper in California. Its population dynamics and ability to transmit Xylella fastidiosa were monitored over a 2-year period in California’s San Joaquin Valley. Collections of individuals fr...

  6. Dynamic Processes in Biology, Chemistry, and Materials Science: Opportunities for UltraFast Transmission Electron Microscopy - Workshop Summary Report

    SciTech Connect

    Kabius, Bernd C.; Browning, Nigel D.; Thevuthasan, Suntharampillai; Diehl, Barbara L.; Stach, Eric A.

    2012-07-25

    This report summarizes a 2011 workshop that addressed the potential role of rapid, time-resolved electron microscopy measurements in accelerating the solution of important scientific and technical problems. A series of U.S. Department of Energy (DOE) and National Academy of Science workshops have highlighted the critical role advanced research tools play in addressing scientific challenges relevant to biology, sustainable energy, and technologies that will fuel economic development without degrading our environment. Among the specific capability needs for advancing science and technology are tools that extract more detailed information in realistic environments (in situ or operando) at extreme conditions (pressure and temperature) and as a function of time (dynamic and time-dependent). One of the DOE workshops, Future Science Needs and Opportunities for Electron Scattering: Next Generation Instrumentation and Beyond, specifically addressed the importance of electron-based characterization methods for a wide range of energy-relevant Grand Scientific Challenges. Boosted by the electron optical advancement in the last decade, a diversity of in situ capabilities already is available in many laboratories. The obvious remaining major capability gap in electron microscopy is in the ability to make these direct in situ observations over a broad spectrum of fast (µs) to ultrafast (picosecond [ps] and faster) temporal regimes. In an effort to address current capability gaps, EMSL, the Environmental Molecular Sciences Laboratory, organized an Ultrafast Electron Microscopy Workshop, held June 14-15, 2011, with the primary goal to identify the scientific needs that could be met by creating a facility capable of a strongly improved time resolution with integrated in situ capabilities. The workshop brought together more than 40 leading scientists involved in applying and/or advancing electron microscopy to address important scientific problems of relevance to DOE’s research

  7. TRACKING CODE DEVELOPMENT FOR BEAM DYNAMICS OPTIMIZATION

    SciTech Connect

    Yang, L.

    2011-03-28

    Dynamic aperture (DA) optimization with direct particle tracking is a straight forward approach when the computing power is permitted. It can have various realistic errors included and is more close than theoretical estimations. In this approach, a fast and parallel tracking code could be very helpful. In this presentation, we describe an implementation of storage ring particle tracking code TESLA for beam dynamics optimization. It supports MPI based parallel computing and is robust as DA calculation engine. This code has been used in the NSLS-II dynamics optimizations and obtained promising performance.

  8. Contributions of Dynamic Systems Theory to Cognitive Development

    ERIC Educational Resources Information Center

    Spencer, John P.; Austin, Andrew; Schutte, Anne R.

    2012-01-01

    We examine the contributions of dynamic systems theory to the field of cognitive development, focusing on modeling using dynamic neural fields. After introducing central concepts of dynamic field theory (DFT), we probe empirical predictions and findings around two examples--the DFT of infant perseverative reaching that explains Piaget's A-not-B…

  9. Advances in cryogenic transmission electron microscopy for the characterization of dynamic self-assembling nanostructures

    PubMed Central

    Newcomb, Christina J.; Moyer, Tyson J.; Lee, Sungsoo S.; Stupp, Samuel I.

    2012-01-01

    Elucidating the structural information of nanoscale materials in their solvent-exposed state is crucial, as a result, cryogenic transmission electron microscopy (cryo-TEM) has become an increasingly popular technique in the materials science, chemistry, and biology communities. Cryo-TEM provides a method to directly visualize the specimen structure in a solution-state through a thin film of vitrified solvent. This technique complements X-ray, neutron, and light scattering methods that probe the statistical average of all species present; furthermore, cryo-TEM can be used to observe changes in structure over time. In the area of self-assembly, this tool has been particularly powerful for the characterization of natural and synthetic small molecule assemblies, as well as hybrid organic–inorganic composites. In this review, we discuss recent advances in cryogenic TEM in the context of self-assembling systems with emphasis on characterization of transitions observed in response to external stimuli. PMID:23204913

  10. Neural field dynamics under variation of local and global connectivity and finite transmission speed

    NASA Astrophysics Data System (ADS)

    Qubbaj, Murad R.; Jirsa, Viktor K.

    2009-12-01

    Spatially continuous networks with heterogeneous connections are ubiquitous in biological systems, in particular neural systems. To understand the mutual effects of locally homogeneous and globally heterogeneous connectivity, we investigate the stability of the steady state activity of a neural field as a function of its connectivity. The variation of the connectivity is implemented through manipulation of a heterogeneous two-point connection embedded into the otherwise homogeneous connectivity matrix and by variation of the connectivity strength and transmission speed. Detailed examples including the Ginzburg-Landau equation and various other local architectures are discussed. Our analysis shows that developmental changes such as the myelination of the cortical large-scale fiber system generally result in the stabilization of steady state activity independent of the local connectivity. Non-oscillatory instabilities are shown to be independent of any influences of time delay.

  11. Transmission dynamics of HIV-1 subtype B in the Basque Country, Spain.

    PubMed

    Patiño-Galindo, J A; Thomson, Michael M; Pérez-Álvarez, Lucía; Delgado, Elena; Cuevas, María Teresa; Fernández-García, Aurora; Nájera, Rafael; Iribarren, José A; Cilla, Gustavo; López-Soria, Leyre; Lezaun, María J; Cisterna, Ramón; González-Candelas, F

    2016-06-01

    This work was aimed to study the HIV-1 subtype B epidemics in the Basque Country, Spain. 1727 HIV-1 subtype B sequences comprising protease and reverse transcriptase (PR/RT) coding regions, sampled between 2001 and 2008, were analyzed. 156 transmission clusters were detected by means of phylogenetic analyses. Most of them comprised less than 4 individuals and, in total, they included 441 patients. Six clusters comprised 10 or more patients and were further analyzed in order to study their origin and diversification. Four clusters included men who had unprotected homosexual sex (MSM), one group was formed by intravenous drug users (IDUs), and another included both IDUs and people infected through unprotected heterosexual sex (HTs). Most of these clusters originated from the mid-1980s to the mid-1990s. Only one cluster, formed by MSM, originated after 2000. The time between infections was significantly lower in MSM groups than in those containing IDUs (P-value <0.0001). Nucleoside RT and non-nucleoside RT inhibitor (NRTI and NNRTI)-resistance mutations to antiretroviral treatment were found in these six clusters except the most recent MSM group, but only the IDU clusters presented protease inhibitor (PI)-resistance mutations. The most prevalent mutations for each inhibitor class were PI L90M, NRTI T215D/Y/F, and NNRTI K103N, which were also among the most prevalent resistant variants in the whole dataset. In conclusion, while most infections occur as isolated introductions into the population, the number of infections found to be epidemiologically related within the Basque Country is significant. Public health control measures should be reinforced to prevent the further expansion of transmission clusters and resistant mutations occurring within them. PMID:26921800

  12. Development of large high-voltage pressure insulators for the princeton TFTR flexible transmission lines

    NASA Astrophysics Data System (ADS)

    Scalise, D. T.; Fong, E.; Haughian, J.; Prechter, R.

    1987-04-01

    Specially formulated insulator materials with improved strength and high-voltage properties were developed and used for critical components of the flexible transmission lines to the TFTR neutral beam ion sources. These critical components are plates which support central conductors as they exit the high-voltage power supply and enter the ion source enclosure. Each plate acts both as a high-voltage insulator and as a pressure barrier to the SF 6 insulating gas. The original plate was made of commercial glass-epoxy laminate which limited the plate voltage capacity. The newly developed insulator is made of specially-formulated cycloalphatic di-epoxide whose isotropic properties exhibit increased are resistance. It is cast in one piece with skirts which greatly increase the breakdown voltage. This paper discusses the design, fabrication and testing of the new insulator.

  13. Differential plague-transmission dynamics determine Yersinia pestis population genetic structure on local, regional, and global scales

    PubMed Central

    Girard, Jessica M.; Wagner, David M.; Vogler, Amy J.; Keys, Christine; Allender, Christopher J.; Drickamer, Lee C.; Keim, Paul

    2004-01-01

    Plague, the disease caused by the bacterium Yersinia pestis, has greatly impacted human civilization. Y. pestis is a successful global pathogen, with active foci on all continents except Australia and Antarctica. Because the Y. pestis genome is highly monomorphic, previous attempts to characterize the population genetic structure within a single focus have been largely unsuccessful. Here we report that highly mutable marker loci allow determination of Y. pestis population genetic structure and tracking of transmission patterns at two spatial scales within a single focus. In addition, we found that in vitro mutation rates for these loci are similar to those observed in vivo, which allowed us to develop a mutation-rate-based model to examine transmission mechanisms. Our model suggests there are two primary components of plague ecology: a rapid expansion phase for population growth and dispersal followed by a slower persistence phase. This pattern seems consistent across local, regional, and even global scales. PMID:15173603

  14. Blocking HIV-1 transmission in the female reproductive tract: from microbicide development to exploring local antiviral responses

    PubMed Central

    Eid, Sahar G; Mangan, Niamh E; Hertzog, Paul J; Mak, Johnson

    2015-01-01

    The majority of new HIV-1 infections are transmitted sexually by penetrating the mucosal barrier to infect target cells. The development of microbicides to restrain heterosexual HIV-1 transmission in the past two decades has proven to be a challenging endeavor. Therefore, better understanding of the tissue environment in the female reproductive tract may assist in the development of the next generation of microbicides to prevent HIV-1 transmission. In this review, we highlight the important factors involved in the heterosexual transmission of HIV-1, provide an update on microbicides' clinical trials, and discuss how different delivery platforms and local immunity may empower the development of next generation of microbicide to block HIV-1 transmission in the female reproductive tract. PMID:26682051

  15. Cable insulation development (1). Superconducting power transmission system development (2). Semiannual report, 1 April 1985-30 September 1985

    SciTech Connect

    Not Available

    1986-04-07

    Objective of the program is to develop an undergound superconducting power transmission system which is economical and technically attractive to the utility industry. The system would be capable of carrying very large blocks of electric power, thus enabling it to supplant overhead lines in urban and suburban areas and regions of natural beauty. the program consisted initially of work in the laboratory to develop suitable materials, cryostats and cable concepts. The materials work covers the development and testing of suitable superconductors and dielectric insulation. The laboratory work has now been extended to an outside test facility which represents an intermediate step between the laboratory scale and a full-scale system. The facility allows cables several hundred feet long to be tested under realistic conditions. Six operating runs of two to four weeks duration each have been accomplished.

  16. Abnormal etioplast development in barley seedlings infected with BSMV by seed transmission.

    PubMed

    Harsányi, Anett; Böddi, Béla; Bóka, Károly; Almási, Asztéria; Gáborjányi, Richard

    2002-01-01

    The effect of barley stripe mosaic hordeivirus (BSMV) was studied on the ultrastructure of etioplasts, protochlorophyllide forms and the greening process of barley (Hordeum vulgare cv. Pannónia) plants infected by seed transmission. The leaves of 7- to 11-day-old etiolated seedlings were examined by transmission electron microscopy, fluorescence and absorption spectroscopy. The etioplasts of infected seedlings contained smaller prolamellar bodies with less regular membrane structure, while prothylakoid content was higher than in the control. The protochlorophyllide content of virus-infected seedlings was reduced to 74% of the control. In the 77 K fluorescence spectra the relative amount of 655 nm emitting photoactive protochlorophyllide form decreased, and the amount of the 645 and 633 nm emitting forms increased in the infected leaves. A characteristic effect was observed in the process of the Shibata-shift: 40 min delay was observed in the infected leaves. The results of this work proved that BSMV infection delays or inhibits plastid development and the formation of photosynthetic apparatus. PMID:11982946

  17. Bayesian evidence synthesis for a transmission dynamic model for HIV among men who have sex with men

    PubMed Central

    Presanis, A. M.; De Angelis, D.; Goubar, A.; Gill, O. N.; Ades, A. E.

    2011-01-01

    Understanding infectious disease dynamics and the effect on prevalence and incidence is crucial for public health policies. Disease incidence and prevalence are typically not observed directly and increasingly are estimated through the synthesis of indirect information from multiple data sources. We demonstrate how an evidence synthesis approach to the estimation of human immunodeficiency virus (HIV) prevalence in England and Wales can be extended to infer the underlying HIV incidence. Diverse time series of data can be used to obtain yearly “snapshots” (with associated uncertainty) of the proportion of the population in 4 compartments: not at risk, susceptible, HIV positive but undiagnosed, and diagnosed HIV positive. A multistate model for the infection and diagnosis processes is then formulated by expressing the changes in these proportions by a system of differential equations. By parameterizing incidence in terms of prevalence and contact rates, HIV transmission is further modeled. Use of additional data or prior information on demographics, risk behavior change and contact parameters allows simultaneous estimation of the transition rates, compartment prevalences, contact rates, and transmission probabilities. PMID:21525422

  18. Kinetics of liquid-mediated crystallization of amorphous Ge from multi-frame dynamic transmission electron microscopy

    SciTech Connect

    Santala, M. K. Campbell, G. H.; Raoux, S.

    2015-12-21

    The kinetics of laser-induced, liquid-mediated crystallization of amorphous Ge thin films were studied using multi-frame dynamic transmission electron microscopy (DTEM), a nanosecond-scale photo-emission transmission electron microscopy technique. In these experiments, high temperature gradients are established in thin amorphous Ge films with a 12-ns laser pulse with a Gaussian spatial profile. The hottest region at the center of the laser spot crystallizes in ∼100 ns and becomes nano-crystalline. Over the next several hundred nanoseconds crystallization continues radially outward from the nano-crystalline region forming elongated grains, some many microns long. The growth rate during the formation of these radial grains is measured with time-resolved imaging experiments. Crystal growth rates exceed 10 m/s, which are consistent with crystallization mediated by a very thin, undercooled transient liquid layer, rather than a purely solid-state transformation mechanism. The kinetics of this growth mode have been studied in detail under steady-state conditions, but here we provide a detailed study of liquid-mediated growth in high temperature gradients. Unexpectedly, the propagation rate of the crystallization front was observed to remain constant during this growth mode even when passing through large local temperature gradients, in stark contrast to other similar studies that suggested the growth rate changed dramatically. The high throughput of multi-frame DTEM provides gives a more complete picture of the role of temperature and temperature gradient on laser crystallization than previous DTEM experiments.

  19. Viral Transmission Dynamics at Single-Cell Resolution Reveal Transiently Immune Subpopulations Caused by a Carrier State Association

    PubMed Central

    Cenens, William; Makumi, Angela; Govers, Sander K.; Lavigne, Rob; Aertsen, Abram

    2015-01-01

    Monitoring the complex transmission dynamics of a bacterial virus (temperate phage P22) throughout a population of its host (Salmonella Typhimurium) at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. More specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered P22 episome. Upon subsequent division, the daughter cell inheriting this episome became lysogenized by an integration event yielding a prophage, while the other daughter cell became P22-free. However, since the phage carrier cell was shown to overproduce immunity factors that are cytoplasmically inherited by the P22-free daughter cell and further passed down to its siblings, a transiently resistant subpopulation was generated that upon dilution of these immunity factors again became susceptible to P22 infection. The iterative emergence and infection of transiently resistant subpopulations suggests a new bet-hedging strategy by which viruses could manage to sustain both vertical and horizontal transmission routes throughout an infected population without compromising a stable co-existence with their host. PMID:26720743

  20. Kinetics of liquid-mediated crystallization of amorphous Ge from multi-frame dynamic transmission electron microscopy

    SciTech Connect

    Santala, M. K.; Raoux, S.; Campbell, G. H.

    2015-12-24

    The kinetics of laser-induced, liquid-mediated crystallization of amorphous Ge thin films were studied using multi-frame dynamic transmission electron microscopy (DTEM), a nanosecond-scale photo-emission transmission electron microscopy technique. In these experiments, high temperature gradients are established in thin amorphous Ge films with a 12-ns laser pulse with a Gaussian spatial profile. The hottest region at the center of the laser spot crystallizes in ~100 ns and becomes nano-crystalline. Over the next several hundred nanoseconds crystallization continues radially outward from the nano-crystalline region forming elongated grains, some many microns long. The growth rate during the formation of these radial grains is measured with time-resolved imaging experiments. Crystal growth rates exceed 10 m/s, which are consistent with crystallization mediated by a very thin, undercooled transient liquid layer, rather than a purely solid-state transformation mechanism. The kinetics of this growth mode have been studied in detail under steady-state conditions, but here we provide a detailed study of liquid-mediated growth in high temperature gradients. Unexpectedly, the propagation rate of the crystallization front was observed to remain constant during this growth mode even when passing through large local temperature gradients, in stark contrast to other similar studies that suggested the growth rate changed dramatically. As a result, the high throughput of multi-frame DTEM provides gives a more complete picture of the role of temperature and temperature gradient on laser crystallization than previous DTEM experiments.

  1. Crystallization kinetics of the phase change material GeSb6Te measured with dynamic transmission electron microscopy.

    PubMed

    Winseck, M M; Cheng, H-Y; Campbell, G H; Santala, M K

    2016-06-14

    GeSb6Te is a chalcogenide-based phase change material that has shown great ptoential for use in solid-state memory devices. The crystallization kinetics of amorphous thin films of GeSb6Te during laser crystallization were followed with dynamic transmission electron microscopy, a photo-emission electron microscopy technique with nanosecond-scale time resolution. Nine-frame movies of crystal growth were taken during laser crystallization. The nucleation rate is observed to be very low and the growth rates are very high, up to 10.8 m s(-1) for amorphous as-deposited films and significantly higher for an amorphous film subject to sub-threshold laser annealing before crystallization. The measured growth rates exceed any directly measured growth rate of a phase change material. The crystallization is reminiscent of explosive crystallization of elemental semiconductors both in the magnitude of the growth rate and in the resulting crystalline microstructures. PMID:27026479

  2. Transmission Dynamics of Zika Virus in Island Populations: A Modelling Analysis of the 2013-14 French Polynesia Outbreak.

    PubMed

    Kucharski, Adam J; Funk, Sebastian; Eggo, Rosalind M; Mallet, Henri-Pierre; Edmunds, W John; Nilles, Eric J

    2016-05-01

    Between October 2013 and April 2014, more than 30,000 cases of Zika virus (ZIKV) disease were estimated to have attended healthcare facilities in French Polynesia. ZIKV has also been reported in Africa and Asia, and in 2015 the virus spread to South America and the Caribbean. Infection with ZIKV has been associated with neurological complications including Guillain-Barré Syndrome (GBS) and microcephaly, which led the World Health Organization to declare a Public Health Emergency of International Concern in February 2015. To better understand the transmission dynamics of ZIKV, we used a mathematical model to examine the 2013-14 outbreak on the six major archipelagos of French Polynesia. Our median estimates for the basic reproduction number ranged from 2.6-4.8, with an estimated 11.5% (95% CI: 7.32-17.9%) of total infections reported. As a result, we estimated that 94% (95% CI: 91-97%) of the total population of the six archipelagos were infected during the outbreak. Based on the demography of French Polynesia, our results imply that if ZIKV infection provides complete protection against future infection, it would take 12-20 years before there are a sufficient number of susceptible individuals for ZIKV to re-emerge, which is on the same timescale as the circulation of dengue virus serotypes in the region. Our analysis suggests that ZIKV may exhibit similar dynamics to dengue virus in island populations, with transmission characterized by large, sporadic outbreaks with a high proportion of asymptomatic or unreported cases. PMID:27186984

  3. Transmission Dynamics of Zika Virus in Island Populations: A Modelling Analysis of the 2013–14 French Polynesia Outbreak

    PubMed Central

    Kucharski, Adam J.; Funk, Sebastian; Eggo, Rosalind M.; Mallet, Henri-Pierre; Edmunds, W. John; Nilles, Eric J.

    2016-01-01

    Between October 2013 and April 2014, more than 30,000 cases of Zika virus (ZIKV) disease were estimated to have attended healthcare facilities in French Polynesia. ZIKV has also been reported in Africa and Asia, and in 2015 the virus spread to South America and the Caribbean. Infection with ZIKV has been associated with neurological complications including Guillain-Barré Syndrome (GBS) and microcephaly, which led the World Health Organization to declare a Public Health Emergency of International Concern in February 2015. To better understand the transmission dynamics of ZIKV, we used a mathematical model to examine the 2013–14 outbreak on the six major archipelagos of French Polynesia. Our median estimates for the basic reproduction number ranged from 2.6–4.8, with an estimated 11.5% (95% CI: 7.32–17.9%) of total infections reported. As a result, we estimated that 94% (95% CI: 91–97%) of the total population of the six archipelagos were infected during the outbreak. Based on the demography of French Polynesia, our results imply that if ZIKV infection provides complete protection against future infection, it would take 12–20 years before there are a sufficient number of susceptible individuals for ZIKV to re-emerge, which is on the same timescale as the circulation of dengue virus serotypes in the region. Our analysis suggests that ZIKV may exhibit similar dynamics to dengue virus in island populations, with transmission characterized by large, sporadic outbreaks with a high proportion of asymptomatic or unreported cases. PMID:27186984

  4. Numerical simulation of cathode plasma dynamics in magnetically insulated vacuum transmission lines

    SciTech Connect

    Thoma, C.; Genoni, T. C.; Welch, D. R.; Rose, D. V.; Clark, R. E.; Miller, C. L.; Stygar, W. A.; Kiefer, M. L.

    2015-03-15

    A novel algorithm for the simulation of cathode plasmas in particle-in-cell codes is described and applied to investigate cathode plasma evolution in magnetically insulated transmission lines (MITLs). The MITL electron sheath is modeled by a fully kinetic electron species. Electron and ion macroparticles, both modeled as fluid species, form a dense plasma which is initially localized at the cathode surface. Energetic plasma electron particles can be converted to kinetic electrons to resupply the electron flux at the plasma edge (the “effective” cathode). Using this model, we compare results for the time evolution of the cathode plasma and MITL electron flow with a simplified (isothermal) diffusion model. Simulations in 1D show a slow diffusive expansion of the plasma from the cathode surface. But in multiple dimensions, the plasma can expand much more rapidly due to anomalous diffusion caused by an instability due to the strong coupling of a transverse magnetic mode in the electron sheath with the expanding resistive plasma layer.

  5. Lithium electrodeposition dynamics in aprotic electrolyte observed in situ via transmission electron microscopy

    DOE PAGESBeta

    Leenheer, Andrew Jay; Jungjohann, Katherine Leigh; Zavadil, Kevin Robert; Sullivan, John P.; Harris, Charles Thomas

    2015-03-18

    Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm2 leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effectmore » of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. As a result, we discuss the implications for operando STEM liquid-cell imaging and Li-battery applications.« less

  6. Dynamics and properties of waves in a modified Noguchi electrical transmission line.

    PubMed

    Pelap, F B; Kamga, J H; Yamgoue, S B; Ngounou, S M; Ndecfo, J E

    2015-02-01

    We consider a modified Noguchi electrical transmission line and examine the effects of a linear capacitance C(s) on the wave characteristics while considering the semidiscrete approximation. It appears that wave modulations in the network are governed by a dispersive nonlinear Schrödinger equation whose coefficients are shown to be a function of C(s). We show that the use of this linear capacitance makes the filter more selective. We also show that the width of the unstable regions increases while that of the stable regions decreases with C(s) adding consequently the width of the frequency domain where bright solitons exist. Furthermore, we establish the existence of one more region (compared to the work of Marquié et al. [Marquié et al., Phys. Rev. E 49, 828 (1994)]) in the dispersion curve that allows the motion of envelope solitons of higher frequency in the system. Numerical and experimental investigations done on the model confirm our analytical predictions. PMID:25768587

  7. Ebola virus disease outbreak in Nigeria: Transmission dynamics and rapid control.

    PubMed

    Althaus, C L; Low, N; Musa, E O; Shuaib, F; Gsteiger, S

    2015-06-01

    International air travel has already spread Ebola virus disease (EVD) to major cities as part of the unprecedented epidemic that started in Guinea in December 2013. An infected airline passenger arrived in Nigeria on July 20, 2014 and caused an outbreak in Lagos and then Port Harcourt. After a total of 20 reported cases, including 8 deaths, Nigeria was declared EVD free on October 20, 2014. We quantified the impact of early control measures in preventing further spread of EVD in Nigeria and calculated the risk that a single undetected case will cause a new outbreak. We fitted an EVD transmission model to data from the outbreak in Nigeria and estimated the reproduction number of the index case at 9.0 (95% confidence interval [CI]: 5.2-15.6). We also found that the net reproduction number fell below unity 15 days (95% CI: 11-21 days) after the arrival of the index case. Hence, our study illustrates the time window for successful containment of EVD outbreaks caused by infected air travelers. PMID:25979285

  8. Solving the Accelerator-Condenser Coupling Problem in a Nanosecond Dynamic Transmission Electron Microscope

    SciTech Connect

    Reed, B W; LaGrange, T; Shuttlesworth, R M; Gibson, D J; Campbell, G H; Browning, N D

    2009-12-29

    We describe a modification to a transmission electron microscope (TEM) that allows it to briefly (using a pulsed-laser-driven photocathode) operate at currents in excess of 10 mA while keeping the effects of condenser lens aberrations to a minimum. This modification allows real-space imaging of material microstructure with a resolution of order 10 nm over regions several {micro}m across with an exposure time of 15 ns. This is more than 6 orders of magnitude faster than typical video-rate TEM imaging. The key is the addition of a weak magnetic lens to couple the large-diameter high-current beam exiting the accelerator into the acceptance aperture of a conventional TEM condenser lens system. We show that the performance of the system is essentially consistent with models derived from ray tracing and finite element simulations. The instrument can also be operated as a conventional TEM by using the electron gun in a thermionic mode. The modification enables very high electron current densities in {micro}m-sized areas and could also be used in a non-pulsed system for high-throughput imaging and analytical TEM.

  9. Solving the accelerator-condenser coupling problem in a nanosecond dynamic transmission electron microscope.

    PubMed

    Reed, B W; LaGrange, T; Shuttlesworth, R M; Gibson, D J; Campbell, G H; Browning, N D

    2010-05-01

    We describe a modification to a transmission electron microscope (TEM) that allows it to briefly (using a pulsed-laser-driven photocathode) operate at currents in excess of 10 mA while keeping the effects of condenser lens aberrations to a minimum. This modification allows real-space imaging of material microstructure with a resolution of order 10 nm over regions several microm across with an exposure time of 15 ns. This is more than six orders of magnitude faster than typical video-rate TEM imaging. The key is the addition of a weak magnetic lens to couple the large-diameter high-current beam exiting the accelerator into the acceptance aperture of a conventional TEM condenser lens system. We show that the performance of the system is essentially consistent with models derived from ray tracing and finite element simulations. The instrument can also be operated as a conventional TEM by using the electron gun in a thermionic mode. The modification enables very high electron current densities in microm-sized areas and could also be used in a nonpulsed system for high-throughput imaging and analytical TEM. PMID:20515144

  10. Lithium Electrodeposition Dynamics in Aprotic Electrolyte Observed in Situ via Transmission Electron Microscopy.

    PubMed

    Leenheer, Andrew J; Jungjohann, Katherine L; Zavadil, Kevin R; Sullivan, John P; Harris, C Thomas

    2015-04-28

    Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for in situ scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm(2) leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. We discuss the implications for operando STEM liquid-cell imaging and Li-battery applications. PMID:25785517

  11. Global analysis of a dynamical model for transmission of tuberculosis with a general contact rate

    NASA Astrophysics Data System (ADS)

    Bowong, Samuel; Tewa, Jean Jules

    2010-11-01

    This paper deals with the global analysis of a dynamical model for the spread of tuberculosis with a general contact rate. The model exhibits the traditional threshold behavior. We prove that when the basic reproduction ratio is less than unity, then the disease-free equilibrium is globally asymptotically stable and when the basic reproduction ratio is great than unity, a unique endemic equilibrium exists and is globally asymptotically stable under certain conditions. The stability of equilibria is derived through the use of Lyapunov stability theory and LaSalle's invariant set theorem. Numerical simulations are provided to illustrate the theoretical results.

  12. [Intergenerational transmission of trauma--empirical research and family dynamics approach].

    PubMed

    Klütsch, Verena; Reich, Günter

    2012-01-01

    A tendency to pass on traumatic experiences from one generation to the next can be observed in family systems. This continuity manifests itself very differently, e. g. in posttraumatic stress disorders, anxiety disorders, mood disorders, aggressive behavior, social withdrawal or health risk behaviors in the second or third generation. Besides physiological mechanisms (e. g. levels of cortisol) psychosocial "mediators" as attachment security, emotional regulation and availability, parenting style as well as family dynamic processes like family secrets, communication deviances and resulting disturbances of mentalization, disturbances of interpersonal boundaries, conflicts of loyalty and delegation are of relevance. A case example and considerations of resilience processes are given as well. PMID:23155784

  13. Laser transmission welding of absorber-free thermoplastics using dynamic beam superposition

    NASA Astrophysics Data System (ADS)

    Mamuschkin, Viktor; Olowinsky, Alexander; van der Straeten, Kira; Engelmann, Christoph

    2015-03-01

    So far, the main approach to weld absorber-free thermoplastics is exploiting their intrinsic absorption by choosing a proper wavelength of the laser. In order to melt the joining partners spatially restricted at the interface usually optics with a high numerical aperture are used. However, practice shows that the heat affected zone (HAZ) extends over a large area along the beam axis regardless of the optics used. Without clamping or convective cooling thermally induced expansion of the material can cause blowholes or deformation of the irradiated surface. To reduce the thermal stress on the part surface a dynamic beam superposition is investigated with the laser beam performing a precession movement.

  14. Dynamical speckles patterns of action potential transmission effects in squid giant axon membrane

    NASA Astrophysics Data System (ADS)

    Llovera-González, Juan J.; Moreno-Yeras, Alfredo B.; Muramatsu, Mikiya; Soga, Diogo; Serra-Toledo, Rolando L.; Magalhães, Daniel S. F.

    2013-11-01

    Undoubtedly the most important result of the investigations in physiology and biophysics was the discovery of the electrochemical mechanism of propagation of the action potential in nerves that was made by Hodgkin and Huxley during the first half of the past century. Since some decades ago diverse experiments about the electro optical properties of the axon membrane there was published using the most diverse optical experimental procedures6-10. In this paper some results of a dynamical speckle technique applied for obtaining microscopic images of a section of a squid giant axon membrane during the activation by electrical impulses and his digital process are presented.

  15. [Transmission dynamics and cost-effectiveness of rabies control in dogs and humans in an African city].

    PubMed

    Zinsstag, J; Dürr, S; Penny, M A; Mindekem, R; Roth, F; Menendez Gonzalez, S; Naissengar, S; Hattendorf, J

    2011-12-01

    Control of human rabies in developing countries depends on prevention in dogs. The purpose of this study was to evaluate the cost-saving potential for the public health sector of intervention to control rabies in animal-host reservoirs. An existing deterministic model was adapted to allow study of dog-to-human rabies transmission. Model parameters were fitted to data from routine weekly reports on the number of rabid dogs and human rabies exposures in N'Djamena, Chad. At the onset of study, the estimated effective reproductive ratio (Re) was 1.01 indicating stable low-level endemic rabies transmission. Simulations were performed to determine what effects mass vaccination and culling of dogs would have on the incidence of human rabies. Findings showed that a mass campaign allowing single parenteral vaccination of at least 70% of the canine population would be sufficient to interrupt transmission of rabies to humans for at least 6 years. The cost-effectiveness of mass dog vaccination was compared to that of "postexposure prophylaxis" (PEP) which would not reduce future human exposure. Results showed that a sustained 5-year PEP program together with a dog-vaccination campaign would be as cost-effective as PEP alone. Beyond a time-frame of 7 years, combining parenteral dog vaccination campaigns with human PEP appeared to be more cost-effective than human PEP alone. PMID:22393628

  16. California Energy Commission Public Interest EnergyResearch/Energy System Integration -- Transmission-Planning Research&Development Scoping Project

    SciTech Connect

    Eto, Joseph H.; Lesieutre, Bernard; Widergren, Steven

    2004-07-01

    The objective of this Public Interest Energy Research (PIER)scoping project is to identify options for public-interest research and development (R&D) to improve transmission-planning tools, techniques, and methods. The information presented was gathered through a review of current California utility, California Independent System Operator (ISO), and related western states electricity transmission-planning activities and emerging needs. This report presents the project teams findings organized under six topic areas and identifies 17 distinct R&D activities to improve transmission-planning in California and the West. The findings in this report are intended for use, along with other materials, by PIER staff, to facilitate discussions with stakeholders that will ultimately lead to development of a portfolio of transmission-planning R&D activities for the PIER program.

  17. Intergenerational Transmission of Adaptive Functioning: A Test of the Interactionist Model of SES and Human Development

    PubMed Central

    Schofield, Thomas J.; Martin, Monica J.; Conger, Rand D.; Neppl, Tricia K.; Donnellan, M. Brent; Conger, Katherine J.

    2009-01-01

    The Interactionist Model of human development (Conger & Donellan, 2007) proposes that the association between socioeconomic status (SES) and human development involves a dynamic interplay that includes both social causation (SES influences human development) and social selection (individual characteristics affect SES). Using a multigenerational dataset involving 271 families, the current study finds empirical support for the Interactionist Model. Adolescent personality characteristics indicative of social competence, goal-setting, hard work, and emotional stability predicted later SES, parenting, and family characteristics that were related to the positive development of a third generation child. Processes of both social selection and social causation appear to account for the association between SES and dimensions of human development indicative of healthy functioning across multiple generations. PMID:21291427

  18. [Dynamic transmission of Schistosoma by Biomphalaria pfeifferi in the region of Man in Côte d'Ivoire].

    PubMed

    Yapi Yapi, G; Touré, M; Boka, O M; Tia, E; Boby, O A-M

    2014-12-01

    Intestinal schistosomiasis by Schistosoma mansoni is a parasitary affection transmitted in West Africa by the mollusc Biomphalaria pfeifferi. Transmission dynamic of schistosomiasis by Biomphalaria pfeifferi has seldom been investigated in Côte d'Ivoire. In the framework of a research project on the epidemiology of schistosomiasis in the natural forest ecosystems, this study was performed longitudinally over a period of three years in Man region, in western Côte d'Ivoire. The trial set up from 1986 to 1989 and the project was funded by the World Health Organization. The general objective is to design a strategy of schistosomiasis control based on chemotherapy. The approach aims at interrupting or considerably reducing the reinfections, prolonging in that way the duration of the positive effects of the chemotherapy. The specific objectives assigned to the work consisted in studying the dynamic of the B. pfeifferi population and the infection of B. pfeifferi. To achieve our objectives, diverse methods (i: the molluscs sampling by two prospectors during 15 minutes per study site and ii: individual isolation of molluscs in test tubes with 5 or 10 mL of filtered water and exposure to light) have been used. They enabled us in the sampling of the intermediary host molluscs of Schistosoma and seek their infections. The results show that apparent high densities of B. pfeifferi can be observed at the end of the dry season and at the beginning of rainy seasons. In addition, the variation of relative abundance of intermediary host molluscs of Schistosoma is significantly influenced by rainfall and the system of water ways. The period of transmission of the infection to man is six months at Gueupleu village and ten months at Botonguiné village. In order to optimize the effect of chemotherapy in these sites of transmission characterized by a high level of endemy (68 %), an extreme mobility of human populations and a multiplicity of contamination sites, this study should not

  19. Understanding the transmission dynamics of Leishmania donovani to provide robust evidence for interventions to eliminate visceral leishmaniasis in Bihar, India.

    PubMed

    Cameron, Mary M; Acosta-Serrano, Alvaro; Bern, Caryn; Boelaert, Marleen; den Boer, Margriet; Burza, Sakib; Chapman, Lloyd A C; Chaskopoulou, Alexandra; Coleman, Michael; Courtenay, Orin; Croft, Simon; Das, Pradeep; Dilger, Erin; Foster, Geraldine; Garlapati, Rajesh; Haines, Lee; Harris, Angela; Hemingway, Janet; Hollingsworth, T Déirdre; Jervis, Sarah; Medley, Graham; Miles, Michael; Paine, Mark; Picado, Albert; Poché, Richard; Ready, Paul; Rogers, Matthew; Rowland, Mark; Sundar, Shyam; de Vlas, Sake J; Weetman, David

    2016-01-01

    Visceral Leishmaniasis (VL) is a neglected vector-borne disease. In India, it is transmitted to humans by Leishmania donovani-infected Phlebotomus argentipes sand flies. In 2005, VL was targeted for elimination by the governments of India, Nepal and Bangladesh by 2015. The elimination strategy consists of rapid case detection, treatment of VL cases and vector control using indoor residual spraying (IRS). However, to achieve sustained elimination of VL, an appropriate post elimination surveillance programme should be designed, and crucial knowledge gaps in vector bionomics, human infection and transmission need to be addressed. This review examines the outstanding knowledge gaps, specifically in the context of Bihar State, India.The knowledge gaps in vector bionomics that will be of immediate benefit to current control operations include better estimates of human biting rates and natural infection rates of P. argentipes, with L. donovani, and how these vary spatially, temporally and in response to IRS. The relative importance of indoor and outdoor transmission, and how P. argentipes disperse, are also unknown. With respect to human transmission it is important to use a range of diagnostic tools to distinguish individuals in endemic communities into those who: 1) are to going to progress to clinical VL, 2) are immune/refractory to infection and 3) have had past exposure to sand flies.It is crucial to keep in mind that close to elimination, and post-elimination, VL cases will become infrequent, so it is vital to define what the surveillance programme should target and how it should be designed to prevent resurgence. Therefore, a better understanding of the transmission dynamics of VL, in particular of how rates of infection in humans and sand flies vary as functions of each other, is required to guide VL elimination efforts and ensure sustained elimination in the Indian subcontinent. By collecting contemporary entomological and human data in the same geographical

  20. Wind power development in the United States: Effects of policies and electricity transmission congestion

    NASA Astrophysics Data System (ADS)

    Hitaj, Claudia

    In this dissertation, I analyze the drivers of wind power development in the United States as well as the relationship between renewable power plant location and transmission congestion and emissions levels. I first examine the role of government renewable energy incentives and access to the electricity grid on investment in wind power plants across counties from 1998-2007. The results indicate that the federal production tax credit, state-level sales tax credit and production incentives play an important role in promoting wind power. In addition, higher wind power penetration levels can be achieved by bringing more parts of the electricity transmission grid under independent system operator regulation. I conclude that state and federal government policies play a significant role in wind power development both by providing financial support and by improving physical and procedural access to the electricity grid. Second, I examine the effect of renewable power plant location on electricity transmission congestion levels and system-wide emissions levels in a theoretical model and a simulation study. A new renewable plant takes the effect of congestion on its own output into account, but ignores the effect of its marginal contribution to congestion on output from existing plants, which results in curtailment of renewable power. Though pricing congestion removes the externality and reduces curtailment, I find that in the absence of a price on emissions, pricing congestion may in some cases actually increase system-wide emissions. The final part of my dissertation deals with an econometric issue that emerged from the empirical analysis of the drivers of wind power. I study the effect of the degree of censoring on random-effects Tobit estimates in finite sample with a particular focus on severe censoring, when the percentage of uncensored observations reaches 1 to 5 percent. The results show that the Tobit model performs well even at 5 percent uncensored observations

  1. Complexities of Organization Dynamics and Development: Leaders and Managers

    ERIC Educational Resources Information Center

    Nderu-Boddington, Eulalee

    2008-01-01

    This article shows the theoretical framework for understanding organizational dynamics and development - the change theory and subordinate relationships within contemporary organizations. The emphasis is on power strategies and the relationship to organizational dynamics and development. The integrative process broadens the understanding of…

  2. Transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  3. The commercial development of water repellent coatings for high voltage transmission lines

    SciTech Connect

    Hunter, S. R.; Daniel, A.

    2013-10-31

    The purpose of the Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and Southwire Company was to jointly develop a low cost, commercially viable, water-repellant anti-icing coating system for high voltage transmission lines. Icing of power lines and other structures caused by freezing rain events occurs annually in the United States, and leads to severe and prolonged power outages. These outages cause untold economic and personal distress for many American families and businesses. Researchers at the Department of Energy?s Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee have previously developed a set of superhydrophobic coatings with remarkable anti-icing properties that could potentially be sprayed or painted onto high-tension power lines and pylons. These coatings drastically reduce ice accumulation on these structures during freezing rain events. The project involved obtaining technical input, supplies and test high voltage cables from Southwire, along with the joint development of anti-icing coating techniques, which would result in a commercial license agreement between Southwire and ORNL, and potentially other companies requiring water repellent anti-icing coatings.

  4. The commercial development of water repellent coatings for high voltage transmission lines

    SciTech Connect

    Hunter, Scott Robert

    2013-10-01

    The purpose of the Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and Southwire Company was to jointly develop a low cost, commercially viable, water-repellant anti-icing coating system for high voltage transmission lines. Icing of power lines and other structures caused by freezing rain events occurs annually in the United States, and leads to severe and prolonged power outages. These outages cause untold economic and personal distress for many American families and businesses. Researchers at the Department of Energy s Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee have previously developed a set of superhydrophobic coatings with remarkable anti-icing properties that could potentially be sprayed or painted onto high-tension power lines and pylons. These coatings drastically reduce ice accumulation on these structures during freezing rain events. The project involved obtaining technical input, supplies and test high voltage cables from Southwire, along with the joint development of anti-icing coating techniques, which would result in a commercial license agreement between Southwire and ORNL, and potentially other companies requiring water repellent anti-icing coatings.

  5. Molecular Dynamics Investigation of a Mechanism of Allosteric Signal Transmission in Ribosomes.

    PubMed

    Makarov, G I; Golovin, A V; Sumbatyan, N V; Bogdanov, A A

    2015-08-01

    The ribosome is a molecular machine that synthesizes all cellular proteins via translation of genetic information encoded in polynucleotide chain of messenger RNA. Transition between different stages of the ribosome working cycle is strictly coordinated by changes in structure and mutual position both of subunits of the ribosome and its ligands. Therein, information regarding structural transformations is transmitted between functional centers of the ribosome through specific signals. Usually, functional centers of ribosomes are located at a distance reaching up to several tens of angstroms, and it is believed that such signals are transduced allosterically. In our study, we attempted to answer the question of how allosteric signal can be transmitted from one of the so-called sensory elements of ribosomal tunnel (RT) to the peptidyl transferase center (PTC). A segment of RT wall from the E. coli ribosome composed of nucleotide residues A2058, A2059, m(2)A2503, G2061, A2062, and C2063 of its 23S rRNA was examined by molecular dynamics simulations. It was found that a potential signal transduction pathway A2058-C2063 acted as a dynamic ensemble of interdependent conformational states, wherein cascade-like changes can occur. It was assumed that structural rearrangement in the A2058-C2063 RT segment results in reversible inactivation of PTC due to a strong stacking contact between functionally important U2585 residue of the PTC and nucleotide residue C2063. A potential role for the observed conformational transition in the A2058-C2063 segment for regulating ribosome activity is discussed. PMID:26547073

  6. Modeling household and community transmission of Ebola virus disease: Epidemic growth, spatial dynamics and insights for epidemic control.

    PubMed

    Kiskowski, Maria; Chowell, Gerardo

    2016-02-17

    The mechanisms behind the sub-exponential growth dynamics of the West Africa Ebola virus disease epidemic could be related to improved control of the epidemic and the result of reduced disease transmission in spatially constrained contact structures. An individual-based, stochastic network model is used to model immediate and delayed epidemic control in the context of social contact networks and investigate the extent to which the relative role of these factors may be determined during an outbreak. We find that in general, epidemics quickly establish a dynamic equilibrium of infections in the form of a wave of fixed size and speed traveling through the contact network. Both greater epidemic control and limited community mixing decrease the size of an infectious wave. However, for a fixed wave size, epidemic control (in contrast with limited community mixing) results in lower community saturation and a wave that moves more quickly through the contact network. We also found that the level of epidemic control has a disproportionately greater reductive effect on larger waves, so that a small wave requires nearly as much epidemic control as a larger wave to end an epidemic. PMID:26399855

  7. Modeling household and community transmission of Ebola virus disease: Epidemic growth, spatial dynamics and insights for epidemic control

    PubMed Central

    Kiskowski, Maria; Chowell, Gerardo

    2016-01-01

    The mechanisms behind the sub-exponential growth dynamics of the West Africa Ebola virus disease epidemic could be related to improved control of the epidemic and the result of reduced disease transmission in spatially constrained contact structures. An individual-based, stochastic network model is used to model immediate and delayed epidemic control in the context of social contact networks and investigate the extent to which the relative role of these factors may be determined during an outbreak. We find that in general, epidemics quickly establish a dynamic equilibrium of infections in the form of a wave of fixed size and speed traveling through the contact network. Both greater epidemic control and limited community mixing decrease the size of an infectious wave. However, for a fixed wave size, epidemic control (in contrast with limited community mixing) results in lower community saturation and a wave that moves more quickly through the contact network. We also found that the level of epidemic control has a disproportionately greater reductive effect on larger waves, so that a small wave requires nearly as much epidemic control as a larger wave to end an epidemic. PMID:26399855

  8. Space structure (dynamics and control) theme development

    NASA Technical Reports Server (NTRS)

    Russell, Richard A.; Gates, Richard M.

    1988-01-01

    A study was made to define the long-range technical objectives and goals for the Space Structure (Dynamics and Control) theme area. The approach was to evaluate ongoing and proposed technology activities such that the technology gaps and voids could be identified. After the technology needs were identified, a set of recommended experimental activities was defined including the technical objectives of each and their relationship.

  9. Infrastructure of Baltic Region Transmission System: Analysis of Technical and Economic Factors of its Development

    NASA Astrophysics Data System (ADS)

    Obushevs, A.; Oleinikova, I.; Mutule, A.

    2014-08-01

    The operational conditions of new networks dictate new requirements for the transmission planning, which would include the electricity market figures and a sizable involvement of renewable generation. This paper focuses on the transmission expansion planning techniques based on the calculations of optimal power flows and on the concept of development planning and sustainability. A description is given for the mathematical model of calculations and analysis of transmission system. The results have shown that the Baltic transmission system infrastructure can successfully be analyzed based on the proposed methodology and developed mathematical model Baltijas valstu (Latvijas, Lietuvas un Igaunijas) energosistēmas ir cieši saistītas vēsturiski, un to darbība nav iespējama bez savstarpējas sadarbības attīstības un darba režīmu jautājumos. Ekonomisko attiecību īstenošanu enerģētikas sektorā paātrināja elektroenerģijas tirgus attīstība. Baltijas valstu enerģētikas politika ir integrēta ES enerģētikas stratēģijas sastāvdaļa, nosakot trīs galvenos mērķus: enerģētikas nozares konkurētspēja, ilgtspējīga attīstība un drošība. Visas trīs Baltijas energosistēmas veica lielu darba apjomu iekārtu modernizācijā un standartu saskaņošanā, kuras ir saskaņā ar Eiropas Savienības prasībām, kā arī par tirgus attiecību un tehnoloģiju standartu ieviešanu, lai nodrošinātu energoapgādes drošību un elektroenerģijas pieejamību patērētājiem Tomēr, ņemot vērā strauji mainīgos ārējos apstākļus, it īpaši ģeopolitiskos faktorus, Baltijas valstu enerģētikas politika būtu jāizskata ar mērķi novērtēt, kā šie faktori ietekmē energosistēmas ilgtspējīgu attīstību kopumā. No iepriekš minētā izriet, ka nepieciešama jauna nacionāla enerģētikas stratēģija, kura stiprinātu efektīvu ekonomisko un sociālo pamatu ilgtspējīgu attīstību Baltijas valstu nacionālā ekonomikā. Šī darba m

  10. Development of the Tensor CT Algorithm for Strain Tomography Using Bragg-edge Neutron Transmission

    NASA Astrophysics Data System (ADS)

    Sato, Hirotaka; Shiota, Yoshinori; Shinohara, Takenao; Kamiyama, Takashi; Ohnuma, Masato; Furusaka, Michihiro; Kiyanagi, Yoshiaki

    The tensor CT algorithm for strain tomography using the Bragg-edge neutron transmission spectroscopy is presented. Crystal lattice strain is not scalar but is a tensorwhich changesdepending on the observation angle. Therefore, since traditional"scalar" CT algorithms cannot be applied to tomography of strain, the development of a "tensor" CT algorithm is needed. Aiming at further developments in the future, we first developed a ML-EM based versatile tensor tomography using ofa simple algorithm withsmall restriction. The basic concept is to simultaneously reconstruct multiple strain-tensor components (scalar quantities of normal strain and shear strain) existing at a certain position. In the actual CT image reconstruction, it is important to consider the angular dependence of each tensor component. Through the simulation studies on axially-symmetric and axially-asymmetric distributionscomposed of two strain components and experimental demonstration using the axially-symmetric VAMAS standard sample, we found some important points for strain-tensor tomography. The angle-dependent back-projection procedure of ML-EM is indispensable fortomography of each tensor component,butsuch function also causes animage distortion which can average each strain value along each strain direction. Also, we found that the optimization of the angle-dependent back-projection procedure is important for further improvements of the tensor CT algorithm.

  11. Development of Parallel Image Detection System Using Annular Pupils for Scanning Transmission Electron Microscope

    SciTech Connect

    Matsutani, Takaomi; Taya, Masaki; Ikuta, Takashi; Tanaka, Takeo; Kimura, Yoshihide; Takai, Yoshizo; Kawasaki, Tadahiro; Ichihashi, Mikio

    2010-10-13

    A parallel image detection system using an annular pupil for electron optics were developed to realize an increase in the depth of focus, aberration-free imaging and separation of amplitude and phase images under scanning transmission electron microscopy (STEM). Apertures for annular pupils able to suppress high-energy electron scattering were developed using a focused ion beam (FIB) technique. The annular apertures were designed with outer diameter of oe 40 {mu}m and inner diameter of oe32 {mu}m. A taper angle varying from 20 deg. to 1 deg. was applied to the slits of the annular apertures to suppress the influence of high-energy electron scattering. Each azimuth angle image on scintillator was detected by a multi-anode photomultiplier tube assembly through 40 optical fibers bundled in a ring shape. To focus the image appearing on the scintillator on optical fibers, an optical lens relay system attached with CCD camera was developed. The system enables the taking of 40 images simultaneously from different scattered directions.

  12. Development of an improved optical transmission technique for black carbon (BC) analysis

    NASA Astrophysics Data System (ADS)

    Ballach, J.; Hitzenberger, R.; Schultz, E.; Jaeschke, W.

    A new optical transmission technique for black carbon (BC) analysis was developed to minimize interferences due to scattering effects in filter samples. A standard thermal analysis method (VDI, 1999) is used to link light attenuation by the filter samples to elemental carbon (EC) concentration. Scattering effects are minimized by immersion of the filters in oil of a similar refractive index, as is often done for microscopy purposes. Light attenuation was measured using both a white light source and a red LED of 650 nm. The usual increase in overestimation of BC concentrations with decreasing BC amount in filter samples was found considerably reduced. Some effects of BC properties (e.g. fractal dimension, microstructure and size distribution) on the specific attenuation coefficient BATN, however, are still present for the treated samples. BATN was found close to 1 m 2 g -1 for dry-dispersed industrial BC and 7 m 2 g -1 for nebulized BC. Good agreement was found between the oil immersion, integrating sphere and a polar photometer technique and Mie calculations. The average specific attenuation coefficient of ambient samples in oil varied between 7 and 11 m 2 g -1 for white light and 6 and 9 m 2 g -1 for red light (LED). BATN was found to have much less site variation for the treated than for the untreated samples. The oil immersion technique improved also the correlation with thermally analyzed EC. This new immersion technique therefore presents a considerable improvement over conventional optical transmission techniques and may therefore serve as a simple, fast and cost-effective alternative to thermal methods.

  13. Real-Time Investigation of Tuberculosis Transmission: Developing the Respiratory Aerosol Sampling Chamber (RASC)

    PubMed Central

    Wood, Robin; Morrow, Carl; Barry, Clifton E.; Bryden, Wayne A.; Call, Charles J.; Hickey, Anthony J.; Rodes, Charles E.; Scriba, Thomas J.; Blackburn, Jonathan; Issarow, Chacha; Mulder, Nicola; Woodward, Jeremy; Moosa, Atica; Singh, Vinayak; Mizrahi, Valerie; Warner, Digby F.

    2016-01-01

    Knowledge of the airborne nature of respiratory disease transmission owes much to the pioneering experiments of Wells and Riley over half a century ago. However, the mechanical, physiological, and immunopathological processes which drive the production of infectious aerosols by a diseased host remain poorly understood. Similarly, very little is known about the specific physiological, metabolic and morphological adaptations which enable pathogens such as Mycobacterium tuberculosis (Mtb) to exit the infected host, survive exposure to the external environment during airborne carriage, and adopt a form that is able to enter the respiratory tract of a new host, avoiding innate immune and physical defenses to establish a nascent infection. As a first step towards addressing these fundamental knowledge gaps which are central to any efforts to interrupt disease transmission, we developed and characterized a small personal clean room comprising an array of sampling devices which enable isolation and representative sampling of airborne particles and organic matter from tuberculosis (TB) patients. The complete unit, termed the Respiratory Aerosol Sampling Chamber (RASC), is instrumented to provide real-time information about the particulate output of a single patient, and to capture samples via a suite of particulate impingers, impactors and filters. Applying the RASC in a clinical setting, we demonstrate that a combination of molecular and microbiological assays, as well as imaging by fluorescence and scanning electron microscopy, can be applied to investigate the identity, viability, and morphology of isolated aerosolized particles. Importantly, from a preliminary panel of active TB patients, we observed the real-time production of large numbers of airborne particles including Mtb, as confirmed by microbiological culture and polymerase chain reaction (PCR) genotyping. Moreover, direct imaging of captured samples revealed the presence of multiple rod-like Mtb organisms whose

  14. Impaired Synaptic Development, Maintenance, and Neuromuscular Transmission in LRP4 Myasthenia

    PubMed Central

    Selcen, Duygu; Ohkawara, Bisei; Shen, Xin-Ming; McEvoy, Kathleen; Ohno, Kinji; Engel, Andrew G.

    2015-01-01

    IMPORTANCE Congenital myasthenic syndromes (CMS) are heterogeneous disorders. Defining the phenotypic features, genetic basis, and pathomechanisms of a CMS is relevant to prognosis, genetic counseling, and therapy. OBJECTIVE To characterize clinical, structural, electrophysiologic, and genetic features of a CMS and search for optimal therapy. DESIGN, SETTINGS, AND PARTICIPANTS Two sisters, 34 and 20 years of age suffering from a CMS affecting the limb-girdle muscles were investigated at an academic medical center by clinical observation, in vitro analysis of neuromuscular transmission, cytochemical and electron microscopy studies of the neuromuscular junction, exome sequencing, expression studies in HEK293 and COS-7 cells, and for response to therapy. MAIN OUTCOMES AND MEASURES We identified the disease gene and mutation, confirmed pathogenicity of the mutation by expression studies, and instituted optimal pharmacotherapy. RESULTS Intercostal muscle endplates (EPs) were abnormally small with attenuated reactivities for the acetylcholine receptor and acetylcholine esterase. Most EPs had poorly differentiated or degenerate junctional folds and some appeared denuded of nerve terminals. The amplitude of the EP potential (EPP), the miniature EPP, and the quantal content of the EPP were all markedly reduced. Exome sequencing identified a novel homozygous p.Glu1233Ala mutation in LRP4, a coreceptor for agrin to activate MuSK, required for EP development and maintenance. Expression studies indicate the mutation compromises ability of LRP4 to bind to, phosphorylate, and activate MuSK. Albuterol improved the patients’ symptoms. CONCLUSIONS AND RELEVANCE We identify a second CMS kinship harboring mutations in LRP4, identify the mechanisms that impair neuromuscular transmission, and mitigate the disease by appropriate therapy. PMID:26052878

  15. Real-Time Investigation of Tuberculosis Transmission: Developing the Respiratory Aerosol Sampling Chamber (RASC).

    PubMed

    Wood, Robin; Morrow, Carl; Barry, Clifton E; Bryden, Wayne A; Call, Charles J; Hickey, Anthony J; Rodes, Charles E; Scriba, Thomas J; Blackburn, Jonathan; Issarow, Chacha; Mulder, Nicola; Woodward, Jeremy; Moosa, Atica; Singh, Vinayak; Mizrahi, Valerie; Warner, Digby F

    2016-01-01

    Knowledge of the airborne nature of respiratory disease transmission owes much to the pioneering experiments of Wells and Riley over half a century ago. However, the mechanical, physiological, and immunopathological processes which drive the production of infectious aerosols by a diseased host remain poorly understood. Similarly, very little is known about the specific physiological, metabolic and morphological adaptations which enable pathogens such as Mycobacterium tuberculosis (Mtb) to exit the infected host, survive exposure to the external environment during airborne carriage, and adopt a form that is able to enter the respiratory tract of a new host, avoiding innate immune and physical defenses to establish a nascent infection. As a first step towards addressing these fundamental knowledge gaps which are central to any efforts to interrupt disease transmission, we developed and characterized a small personal clean room comprising an array of sampling devices which enable isolation and representative sampling of airborne particles and organic matter from tuberculosis (TB) patients. The complete unit, termed the Respiratory Aerosol Sampling Chamber (RASC), is instrumented to provide real-time information about the particulate output of a single patient, and to capture samples via a suite of particulate impingers, impactors and filters. Applying the RASC in a clinical setting, we demonstrate that a combination of molecular and microbiological assays, as well as imaging by fluorescence and scanning electron microscopy, can be applied to investigate the identity, viability, and morphology of isolated aerosolized particles. Importantly, from a preliminary panel of active TB patients, we observed the real-time production of large numbers of airborne particles including Mtb, as confirmed by microbiological culture and polymerase chain reaction (PCR) genotyping. Moreover, direct imaging of captured samples revealed the presence of multiple rod-like Mtb organisms whose

  16. Transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  17. What can mathematical models tell us about the relationship between circular migrations and HIV transmission dynamics?

    PubMed

    Khanna, Aditya S; Dimitrov, Dobromir T; Goodreau, Steven M

    2014-10-01

    Circular migrations are the periodic movement of individuals between multiple locations, observed in parts of sub-Saharan Africa. Relationships between circular migrations and HIV are complex, entailing interactions between migration frequency, partnership structure, and exposure to acute HIV infection. Mathematical modeling is a useful tool for understanding these interactions. Two modeling classes have dominated the HIV epidemiology and policy literature for the last decade: one a form of compartmental models, the other network models. We construct models from each class, using ordinary differential equations and exponential random graph models, respectively. Our analysis suggests that projected HIV prevalence is highly sensitive to the choice of modeling framework. Assuming initial equal HIV prevalence across locations, compartmental models show no association between migration frequency and HIV prevalence or incidence, while network models show that migrations at frequencies shorter than the acute HIV period predict greater HIV incidence and prevalence compared to longer migration periods. These differences are statistically significant when network models are extended to incorporate a requirement for migrant men's multiple partnerships to occur in different locations. In settings with circular migrations, commonly-used forms of compartmental models appear to miss key components of HIV epidemiology stemming from interactions of relational and viral dynamics. PMID:25347807

  18. Evolutionary Dynamics of MERS-CoV: Potential Recombination, Positive Selection and Transmission

    PubMed Central

    Zhang, Zhao; Shen, Libing; Gu, Xun

    2016-01-01

    Middle East respiratory syndrome coronavirus (MERS-CoV) belongs to beta group of coronavirus and was first discovered in 2012. MERS-CoV can infect multiple host species and cause severe diseases in human. We conducted a series of phylogenetic and bioinformatic analyses to study the evolution dynamics of MERS-CoV among different host species with genomic data. Our analyses show: 1) 28 potential recombinant sequences were detected and they can be classified into seven potential recombinant types; 2) The spike (S) protein of MERS-CoV was under strong positive selection when MERS-CoV transmitted from their natural host to human; 3) Six out of nine positive selection sites detected in spike (S) protein are located in its receptor-binding domain which is in direct contact with host cells; 4) MERS-CoV frequently transmitted back and forth between human and camel after it had acquired the human-camel infection capability. Together, these results suggest that potential recombination events might have happened frequently during MERS-CoV’s evolutionary history and the positive selection sites in MERS-CoV’s S protein might enable it to infect human. PMID:27142087

  19. Disease dynamics of Montipora white syndrome within Kaneohe Bay, Oahu, Hawaii: distribution, seasonality, virulence, and transmissibility.

    PubMed

    Aeby, G S; Ross, M; Williams, G J; Lewis, T D; Works, T M

    2010-07-26

    We report on an investigation of Montipora white syndrome (MWS), which is a coral disease reported from Hawaii, U.S.A., that results in tissue loss. Disease surveys of Montipora capitata within Kaneohe Bay (Oahu) found colonies that were affected by MWS on 9 reefs within 3 regions of Kaneohe Bay (south, central, north). Mean MWS prevalence ranged from 0.02 to 0.87% and average number of MWS cases per survey site ranged from 1 to 28 colonies. MWS prevalence and number of cases were significantly lower in the central region as compared to those in the north and south regions of Kaneohe Bay. There was a positive relationship between host abundance and MWS prevalence, and differences in host abundance between sites explained approximately 27% of the variation in MWS prevalence. Reefs in central Kaneohe Bay had lower M. capitata cover and lower MWS levels. MWS prevalence on reefs was neither significantly different between seasons (spring versus fall) nor among 57 tagged colonies that were monitored through time. MWS is a chronic and progressive disease causing M. capitata colonies to lose an average of 3.1% of live tissue mo(-1). Case fatality rate was 28% after 2 yr but recovery occurred in some colonies (32%). Manipulative experiments showed that the disease is acquired through direct contact. This is the first study to examine the dynamics of MWS within Hawaii, and our findings suggest that MWS has the potential to degrade Hawaii's reefs through time. PMID:20853736

  20. Cough Aerosol Cultures of Mycobacterium tuberculosis: Insights on TST / IGRA Discordance and Transmission Dynamics

    PubMed Central

    Jones-López, Edward C.; White, Laura F.; Kirenga, Bruce; Mumbowa, Francis; Ssebidandi, Martin; Moine, Stephanie; Mbabazi, Olive; Mboowa, Gerald; Ayakaka, Irene; Kim, Soyeon; Thornton, Christina S.; Okwera, Alphonse; Joloba, Moses; Fennelly, Kevin P.

    2015-01-01

    Rationale The diagnosis of latent tuberculosis (TB) infection (LTBI) is complicated by the absence of a gold standard. Discordance between tuberculin skin tests (TST) and interferon gamma release assays (IGRA) occurs in 10–20% of individuals, but the underlying mechanisms are poorly understood. Methods We analyzed data from a prospective household contact study that included cough aerosol culture results from index cases, environmental and contact factors. We assessed contacts for LTBI using TST and IGRA at baseline and six weeks. We examined TST/IGRA discordance in qualitative and quantitative analyses, and used multivariable logistic regression analysis with generalized estimating equations to analyze predictors of discordance. Measurements and Results We included 96 TB patients and 384 contacts. Discordance decreased from 15% at baseline to 8% by six weeks. In adjusted analyses, discordance was related to less crowding (p = 0.004), non-cavitary disease (OR 1.41, 95% CI: 1.02–1.96; p = 0.03), and marginally with BCG vaccination in contacts (OR 1.40, 95% CI: 0.99–1.98, p = 0.06). Conclusions We observed significant individual variability and temporal dynamism in TST and IGRA results in household contacts of pulmonary TB cases. Discordance was associated with a less intense infectious exposure, and marginally associated with a BCG-mediated delay in IGRA conversion. Cough aerosols provide an additional dimension to the assessment of infectiousness and risk of infection in contacts. PMID:26394149

  1. Evolutionary Dynamics of MERS-CoV: Potential Recombination, Positive Selection and Transmission.

    PubMed

    Zhang, Zhao; Shen, Libing; Gu, Xun

    2016-01-01

    Middle East respiratory syndrome coronavirus (MERS-CoV) belongs to beta group of coronavirus and was first discovered in 2012. MERS-CoV can infect multiple host species and cause severe diseases in human. We conducted a series of phylogenetic and bioinformatic analyses to study the evolution dynamics of MERS-CoV among different host species with genomic data. Our analyses show: 1) 28 potential recombinant sequences were detected and they can be classified into seven potential recombinant types; 2) The spike (S) protein of MERS-CoV was under strong positive selection when MERS-CoV transmitted from their natural host to human; 3) Six out of nine positive selection sites detected in spike (S) protein are located in its receptor-binding domain which is in direct contact with host cells; 4) MERS-CoV frequently transmitted back and forth between human and camel after it had acquired the human-camel infection capability. Together, these results suggest that potential recombination events might have happened frequently during MERS-CoV's evolutionary history and the positive selection sites in MERS-CoV's S protein might enable it to infect human. PMID:27142087

  2. Dynamics of Cultural Transmission in Native Americans of the High Great Plains

    PubMed Central

    Lycett, Stephen J.

    2014-01-01

    Culture is a phenomenon shared by all humans. Attempts to understand how dynamic factors affect the origin and distribution of cultural elements are, therefore, of interest to all humanity. As case studies go, understanding the distribution of cultural elements in Native American communities during the historical period of the Great Plains would seem a most challenging one. Famously, there is a mixture of powerful internal and external factors, creating-for a relatively brief period in time-a seemingly distinctive set of shared elements from a linguistically diverse set of peoples. This is known across the world as the “Great Plains culture.” Here, quantitative analyses show how different processes operated on two sets of cultural traits among nine High Plains groups. Moccasin decorations exhibit a pattern consistent with geographically-mediated between-group interaction. However, group variations in the religious ceremony of the Sun Dance also reveal evidence of purifying cultural selection associated with historical biases, dividing down ancient linguistic lines. The latter shows that while the conglomeration of “Plains culture” may have been a product of merging new ideas with old, combined with cultural interchange between groups, the details of what was accepted, rejected or elaborated in each case reflected preexisting ideological biases. Although culture may sometimes be a “melting pot,” the analyses show that even in highly fluid situations, cultural mosaics may be indirectly shaped by historical factors that are not always obvious. PMID:25372277

  3. Dynamics of cultural transmission in Native Americans of the high Great Plains.

    PubMed

    Lycett, Stephen J

    2014-01-01

    Culture is a phenomenon shared by all humans. Attempts to understand how dynamic factors affect the origin and distribution of cultural elements are, therefore, of interest to all humanity. As case studies go, understanding the distribution of cultural elements in Native American communities during the historical period of the Great Plains would seem a most challenging one. Famously, there is a mixture of powerful internal and external factors, creating-for a relatively brief period in time-a seemingly distinctive set of shared elements from a linguistically diverse set of peoples. This is known across the world as the "Great Plains culture." Here, quantitative analyses show how different processes operated on two sets of cultural traits among nine High Plains groups. Moccasin decorations exhibit a pattern consistent with geographically-mediated between-group interaction. However, group variations in the religious ceremony of the Sun Dance also reveal evidence of purifying cultural selection associated with historical biases, dividing down ancient linguistic lines. The latter shows that while the conglomeration of "Plains culture" may have been a product of merging new ideas with old, combined with cultural interchange between groups, the details of what was accepted, rejected or elaborated in each case reflected preexisting ideological biases. Although culture may sometimes be a "melting pot," the analyses show that even in highly fluid situations, cultural mosaics may be indirectly shaped by historical factors that are not always obvious. PMID:25372277

  4. WHAT CAN MATHEMATICAL MODELS TELL US ABOUT THE RELATIONSHIP BETWEEN CIRCULAR MIGRATIONS AND HIV TRANSMISSION DYNAMICS?

    PubMed Central

    Khanna, Aditya; Dimitrov, Dobromir; Goodreau, Steven

    2014-01-01

    Circular migrations are the periodic movement of individuals between multiple locations, observed in parts of sub-Saharan Africa. Relationships between circular migrations and HIV are complex, entailing interactions between migration frequency, partnership structure, and exposure to acute HIV infection. Mathematical modeling is a useful tool for understanding these interactions. Two modeling classes have dominated the HIV epidemiology and policy literature for the last decade: one a form of compartmental models, the other network models. We construct models from each class, using ordinary differential equations and exponential random graph models, respectively. Our analysis suggests that projected HIV prevalence is highly sensitive to the choice of modeling framework. Assuming initial equal HIV prevalence across locations, compartmental models show no association between migration frequency and HIV prevalence or incidence, while network models show that migrations at frequencies shorter than the acute HIV period predict greater HIV incidence and prevalence compared to longer migration periods. These differences are statistically significant when network models are extended to incorporate a requirement for migrant mens multiple partnerships to occur in different locations. In settings with circular migrations, commonly-used forms of compartmental models appear to miss key components of HIV epidemiology stemming from interactions of relational and viral dynamics. PMID:25347807

  5. Modelling Transmission of Vector-Borne Pathogens Shows Complex Dynamics When Vector Feeding Sites Are Limited

    PubMed Central

    Kershenbaum, Arik; Stone, Lewi; Ostfeld, Richard S.; Blaustein, Leon

    2012-01-01

    The relationship between species richness and the prevalence of vector-borne disease has been widely studied with a range of outcomes. Increasing the number of host species for a pathogen may decrease infection prevalence (dilution effect), increase it (amplification), or have no effect. We derive a general model, and a specific implementation, which show that when the number of vector feeding sites on each host is limiting, the effects on pathogen dynamics of host population size are more complex than previously thought. The model examines vector-borne disease in the presence of different host species that are either competent or incompetent (i.e. that cannot transmit the pathogen to vectors) as reservoirs for the pathogen. With a single host species present, the basic reproduction ratio R0 is a non-monotonic function of the population size of host individuals (H), i.e. a value exists that maximises R0. Surprisingly, if a reduction in host population size may actually increase R0. Extending this model to a two-host species system, incompetent individuals from the second host species can alter the value of which may reverse the effect on pathogen prevalence of host population reduction. We argue that when vector-feeding sites on hosts are limiting, the net effect of increasing host diversity might not be correctly predicted using simple frequency-dependent epidemiological models. PMID:22590597

  6. 40 Gb/s dynamic wavelength-division-multiplexing/time-division-multiplexing hybrid access network with energy and data stream synchronized transmission.

    PubMed

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Liu, Lei

    2013-09-15

    A dynamic wavelength-division-multiplexing/time-division-multiplexing hybrid access network with energy and data synchronized transmission is proposed to support flexible resource allocation. Dynamic scheduling of wavelength with different split ratio nodes is realized by the control model at the optical distribution network (ODN). All-optical amplification of the optical data signal and energy supply are also incorporated in the ODN. A proof-of-concept experiment is implemented to verify the feasibility of the proposal. PMID:24104799

  7. Rural Development: Goals, Dynamics, Crises and Recommendations.

    ERIC Educational Resources Information Center

    Jehlik, Paul J.

    The continuing transition of rural development from its old to present day form is discussed, treating varied perceptions of its goals and the continuing resolution of approaches through legislation and appropriations. Some of the goals are community development, human resources development, natural resources preservation, and a more equitable…

  8. Infection, Disease, and Transmission Dynamics in Calves after Experimental and Natural Challenge with a Bovine Chlamydia psittaci Isolate

    PubMed Central

    Ostermann, Carola; Rüttger, Anke; Schubert, Evelyn; Schrödl, Wieland; Sachse, Konrad; Reinhold, Petra

    2013-01-01

    Chlamydia (C.) psittaci is the causative agent of psittacosis, a zoonotic disease in birds and man. In addition, C. psittaci has been repeatedly found in domestic animals and is, at least in calves, also able to induce respiratory disease. Knowledge about transmission routes in cattle herds is still deficient, and nothing is known about differences in host response after either experimental or natural exposure to C. psittaci. Therefore, our recently developed respiratory infection model was exploited to evaluate (i) the presence of the pathogen in blood, excretions and air, (ii) the possibility of transmission and (iii) clinical symptoms, acute phase and immune response until 5 weeks after exposure. In this prospective study, intrabronchial inoculation of 108 inclusion-forming units of C. psittaci (n = 21 calves) led to reproducible acute respiratory illness (of approximately one week), accompanied by a systemic inflammatory reaction with an innate immune response dominated by neutrophils. Excretion and/or exhalation of the pathogen was sufficient to transmit the infection to naïve sentinel calves (n = 3) co-housed with the infected animals. Sentinel calves developed mild to subclinical infections only. Notably, excretion of the pathogen, predominantly via feces, occurred more frequently in animals naturally exposed to C. psittaci (i.e. sentinels) as compared to experimentally-inoculated calves. The humoral immune response was generally weak, and did not emerge regularly following experimental infection; however, it was largely absent after naturally acquired infection. PMID:23691148

  9. Dynamic regulation of glycine–GABA co-transmission at spinal inhibitory synapses by neuronal glutamate transporter

    PubMed Central

    Ishibashi, Hitoshi; Yamaguchi, Junya; Nakahata, Yoshihisa; Nabekura, Junichi

    2013-01-01

    Fast inhibitory neurotransmission in the central nervous system is mediated by γ-aminobutyric acid (GABA) and glycine, which are accumulated into synaptic vesicles by a common vesicular inhibitory amino acid transporter (VIAAT) and are then co-released. However, the mechanisms that control the packaging of GABA + glycine into synaptic vesicles are not fully understood. In this study, we demonstrate the dynamic control of the GABA–glycine co-transmission by the neuronal glutamate transporter, using paired whole-cell patch recording from monosynaptically coupled cultured spinal cord neurons derived from VIAAT-Venus transgenic rats. Short step depolarization of presynaptic neurons evoked unitary (cell-to-cell) inhibitory postsynaptic currents (IPSCs). Under normal conditions, the fractional contribution of postsynaptic GABA or glycine receptors to the unitary IPSCs did not change during a 1 h recording. Intracellular loading of GABA or glycine via a patch pipette enhanced the respective components of inhibitory transmission, indicating the importance of the cytoplasmic concentration of inhibitory transmitters. Raised extracellular glutamate levels increased the amplitude of GABAergic IPSCs but reduced glycine release by enhancing glutamate uptake. Similar effects were observed when presynaptic neurons were intracellularly perfused with glutamate. Interestingly, high-frequency trains of stimulation decreased glycinergic IPSCs more than GABAergic IPSCs, and repetitive stimulation occasionally failed to evoke glycinergic but not GABAergic IPSCs. The present results suggest that the enhancement of GABA release by glutamate uptake may be advantageous for rapid vesicular refilling of the inhibitory transmitter at mixed GABA/glycinergic synapses and thus may help prevent hyperexcitability. PMID:23690564

  10. Kinetics of liquid-mediated crystallization of amorphous Ge from multi-frame dynamic transmission electron microscopy

    DOE PAGESBeta

    Santala, M. K.; Raoux, S.; Campbell, G. H.

    2015-12-24

    The kinetics of laser-induced, liquid-mediated crystallization of amorphous Ge thin films were studied using multi-frame dynamic transmission electron microscopy (DTEM), a nanosecond-scale photo-emission transmission electron microscopy technique. In these experiments, high temperature gradients are established in thin amorphous Ge films with a 12-ns laser pulse with a Gaussian spatial profile. The hottest region at the center of the laser spot crystallizes in ~100 ns and becomes nano-crystalline. Over the next several hundred nanoseconds crystallization continues radially outward from the nano-crystalline region forming elongated grains, some many microns long. The growth rate during the formation of these radial grains is measuredmore » with time-resolved imaging experiments. Crystal growth rates exceed 10 m/s, which are consistent with crystallization mediated by a very thin, undercooled transient liquid layer, rather than a purely solid-state transformation mechanism. The kinetics of this growth mode have been studied in detail under steady-state conditions, but here we provide a detailed study of liquid-mediated growth in high temperature gradients. Unexpectedly, the propagation rate of the crystallization front was observed to remain constant during this growth mode even when passing through large local temperature gradients, in stark contrast to other similar studies that suggested the growth rate changed dramatically. As a result, the high throughput of multi-frame DTEM provides gives a more complete picture of the role of temperature and temperature gradient on laser crystallization than previous DTEM experiments.« less

  11. The use of a novel technology to study dynamics of pathogen transmission in the operating room.

    PubMed

    Birnbach, David J; Rosen, Lisa F; Fitzpatrick, Maureen; Carling, Philip; Munoz-Price, L Silvia

    2015-04-01

    Pathogenic organisms have been found in the intraoperative environment, potentially posing a risk of infection that could cause morbidity and mortality. In an effort to understand how a patient's bacteria can be spread throughout the operating room with the anesthesia provider as a vector, we conducted a study using recently developed experimental technology in a simulated operating room environment with a high-fidelity human patient simulator. PMID:24810261

  12. Development of methodology for horizontal axis wind turbine dynamic analysis

    NASA Technical Reports Server (NTRS)

    Dugundji, J.

    1982-01-01

    Horizontal axis wind turbine dynamics were studied. The following findings are summarized: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotor; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastics; and (7) development of simple models for stability and response of wind turbines on flexible towers.

  13. Interaction of electrically evoked activity with intrinsic dynamics of cultured cortical networks with and without functional fast GABAergic synaptic transmission

    PubMed Central

    Baltz, Thomas; Voigt, Thomas

    2015-01-01

    The modulation of neuronal activity by means of electrical stimulation is a successful therapeutic approach for patients suffering from a variety of central nervous system disorders. Prototypic networks formed by cultured cortical neurons represent an important model system to gain general insights in the input–output relationships of neuronal tissue. These networks undergo a multitude of developmental changes during their maturation, such as the excitatory–inhibitory shift of the neurotransmitter GABA. Very few studies have addressed how the output properties to a given stimulus change with ongoing development. Here, we investigate input–output relationships of cultured cortical networks by probing cultures with and without functional GABAAergic synaptic transmission with a set of stimulation paradigms at various stages of maturation. On the cellular level, low stimulation rates (<15 Hz) led to reliable neuronal responses; higher rates were increasingly ineffective. Similarly, on the network level, lowest stimulation rates (<0.1 Hz) lead to maximal output rates at all ages, indicating a network wide refractory period after each stimulus. In cultures aged 3 weeks and older, a gradual recovery of the network excitability within tens of milliseconds was in contrast to an abrupt recovery after about 5 s in cultures with absent GABAAergic synaptic transmission. In these GABA deficient cultures evoked responses were prolonged and had multiple discharges. Furthermore, the network excitability changed periodically, with a very slow spontaneous change of the overall network activity in the minute range, which was not observed in cultures with absent GABAAergic synaptic transmission. The electrically evoked activity of cultured cortical networks, therefore, is governed by at least two potentially interacting mechanisms: A refractory period in the order of a few seconds and a very slow GABA dependent oscillation of the network excitability. PMID:26236196

  14. Interaction of electrically evoked activity with intrinsic dynamics of cultured cortical networks with and without functional fast GABAergic synaptic transmission.

    PubMed

    Baltz, Thomas; Voigt, Thomas

    2015-01-01

    The modulation of neuronal activity by means of electrical stimulation is a successful therapeutic approach for patients suffering from a variety of central nervous system disorders. Prototypic networks formed by cultured cortical neurons represent an important model system to gain general insights in the input-output relationships of neuronal tissue. These networks undergo a multitude of developmental changes during their maturation, such as the excitatory-inhibitory shift of the neurotransmitter GABA. Very few studies have addressed how the output properties to a given stimulus change with ongoing development. Here, we investigate input-output relationships of cultured cortical networks by probing cultures with and without functional GABAAergic synaptic transmission with a set of stimulation paradigms at various stages of maturation. On the cellular level, low stimulation rates (<15 Hz) led to reliable neuronal responses; higher rates were increasingly ineffective. Similarly, on the network level, lowest stimulation rates (<0.1 Hz) lead to maximal output rates at all ages, indicating a network wide refractory period after each stimulus. In cultures aged 3 weeks and older, a gradual recovery of the network excitability within tens of milliseconds was in contrast to an abrupt recovery after about 5 s in cultures with absent GABAAergic synaptic transmission. In these GABA deficient cultures evoked responses were prolonged and had multiple discharges. Furthermore, the network excitability changed periodically, with a very slow spontaneous change of the overall network activity in the minute range, which was not observed in cultures with absent GABAAergic synaptic transmission. The electrically evoked activity of cultured cortical networks, therefore, is governed by at least two potentially interacting mechanisms: A refractory period in the order of a few seconds and a very slow GABA dependent oscillation of the network excitability. PMID:26236196

  15. Adult Personality Development: Dynamics and Processes

    PubMed Central

    Diehl, Manfred; Hooker, Karen

    2013-01-01

    The focus of this special issue of Research in Human Development is on adult personality and how personality may contribute to and be involved in adult development. Specifically, the contributions in this issue focus on the links between personality structures (e.g., traits) and personality processes (e.g., goal pursuit, self--regulation) and emphasize the contributions that intensive repeated measurement approaches can make to the understanding of personality and development across the adult life span. PMID:24068889

  16. Cost-effectiveness of vaccination with a quadrivalent HPV vaccine in Germany using a dynamic transmission model

    PubMed Central

    2012-01-01

    Introduction Persistent infections with human papillomavirus (HPV) are a necessary cause of cervical cancer and are responsible for important morbidity in men and women. Since 2007, HPV vaccination has been recommended and funded for all girls aged 12 to 17 in Germany. A previously published cost-effectiveness analysis, using a static model, showed that a quadrivalent HPV vaccination programme for 12-year-old girls in Germany would be cost effective. Here we present the results from a dynamic transmission model that can be used to evaluate the impact and cost-effectiveness of different vaccination schemas. Methods We adapted a HPV dynamic transmission model, which has been used in other countries, to the German context. The model was used to compare a cervical cancer screening only strategy with a strategy of combining vaccination of females aged 12–17 years old and cervical cancer screening, based on the current recommendations in Germany. In addition, the impact of increasing vaccination coverage in this cohort of females aged 12–17 years old was evaluated in sensitivity analysis. Results The results from this analysis show that the current quadrivalent HPV vaccination programme of females ages 12 to 17 in Germany is cost-effective with an ICER of 5,525€/QALY (quality adjusted life year). The incremental cost-effectiveness ratio (ICER) increased to 10,293€/QALY when the vaccine effects on HPV6/11 diseases were excluded. At steady state, the model predicted that vaccinating girls aged 12 to 17 could reduce the number of HPV 6/11/16/18-related cervical cancers by 65% and genital warts among women and men by 70% and 48%, respectively. The impact on HPV-related disease incidence and costs avoided would occur relatively soon after initiating the vaccine programme, with much of the early impact being due to the prevention of HPV6/11-related genital warts. Conclusions These results show that the current quadrivalent HPV vaccination and cervical cancer screening

  17. Group Development and Group Dynamics in Outdoor Education.

    ERIC Educational Resources Information Center

    McAvoy, Leo H.; Mitten, Denise S.; Stringer, L. Allison; Steckart, James P.; Sproles, Kraig

    This paper reviews the research literature published between 1992 and 1995 on group development and group dynamics in outdoor education and closely allied disciplines. The research is categorized in six general dimensions: (1) how the personal characteristics, skills, and experience that individuals bring to the group influences group dynamics and…

  18. The Importance of Dynamic Systems Approaches for Understanding Development

    ERIC Educational Resources Information Center

    Howe, Mark L.; Lewis, Marc D.

    2005-01-01

    We outline the nature of dynamic systems, both linear and nonlinear, and we review dynamic systems principles that apply well to various aspects of human development, including the emergence of new forms, phases of stability and instability, continuous and discontinuous change, and differentiation among individual trajectories. We then document…

  19. Current Concepts for the IND-Directed Development of Microbicide Products to Prevent the Sexual Transmission of HIV.

    PubMed

    Buckheit, Karen W; Furlan-Freguia, Christian; Ham, Anthony S; Buckheit, Robert W

    2016-01-01

    In the absence of an approved and effective vaccine, topical microbicides have become the strategy of choice to provide women with the ability to prevent the sexual transmission of HIV. Topical microbicides are chemical and physical agents specifically developed and formulated for use in either the vaginal or rectal environment to prevent the sexual transmission of infectious organisms. Although a microbicide product will have many of the same properties as other anti-infective therapeutic agents, the microbicide development pathway has significant differences which reflect the complex biological environment in which the products must act. These challenges to the development of an effective microbicide are reflected in the recently released FDA Guidance document which defines the microbicide development algorithm and includes the evaluation of preclinical efficacy and toxicity, and safety and toxicology, and indicates the necessity of testing of the active pharmaceutical product as well as an optimal formulation for delivery of the microbicide product. The microbicide development algorithm requires evaluation of the potential microbicidal agent and final formulated product in assays which mimic the microenvironment of the vagina and rectum during the sexual transmission of HIV, including the evaluation of activity and cytotoxicity in the appropriate biological matrices, toxicity testing against normal vaginal flora and at standard vaginal pH, testing in ectocervical and colorectal explant tissue, and irritation studies to vaginal, rectal and penile tissue. Herein, we discuss currently accepted practices required for the development of a successful microbicide product which will prevent virus transmission in the vaginal and rectal vaults. PMID:26324047

  20. Development of an energy dispersive spectrometer for a transmission electron microscope utilizing a TES microcalorimeter array

    NASA Astrophysics Data System (ADS)

    Tanaka, Keiichi; Mitsuda, Kazuhisa; Hara, Tom; Maehata, Keisuke; Yamasaki, Noriko Y.; Odawara, Akikazu; Nagata, Atsushi; Watanabe, Katsuaki; Takei, Yoh

    2009-12-01

    A high-energy-resolution energy dispersive spectrometer (EDS) utilizing a TES (transition edge sensor) microcalorimeter array is developed for a transmission electron microscope (TEM). The goals of the development are (1) an energy range of 0.3-10 keV, (2) an energy resolution of FWHM <10 eV, (3) a maximum counting rate of 3 kcps, and (4) a cryogen-free cooling system. We adopted a dilution refrigerator (DR) pre-cooled by a Gifford-McMahon (GM) refrigerator to cool the TES microcalorimeter to ˜100 mK. In order to avoid micro phonics of GM fridge to propagate to the TEM, pressurized He gas is circulated between the DR and the GM to reject heat from the DR. The GM is mechanically well isolated from the TEM. In oder to obtain 3 kcps counting rate, we utilize a ten pixel TES array and read out the signals in parallel wtih ten analog signal channels from cryogenic to room temperature electronics. One of the pixels can be always irradiated by a radio isotope for energy calibration. As the first step, we have attached a single pixel TES system cooled by the cryogen-free cooling system to the TEM and obtained an energy resolution of 8 eV at 1.8 keV without degrading the spatial resolution of the TEM at a 2 Å level. A ten pixel TES system is also being developed from the front-end detector assembly to the room temperature digital electronics. We describe the signal processing system and packaging of the detector assembly.

  1. In-situ transmission electron microscopy and first-principles study of Au (100) surface dislocation dynamics

    NASA Astrophysics Data System (ADS)

    Song, B.; Jansen, J.; Tichelaar, F. D.; Zandbergen, H. W.; Gajewski, G.; Pao, C. W.; Srolovitz, D. J.

    2013-02-01

    In-situ aberration-corrected transmission electron microscopy combined with density functional theory (DFT) calculations are employed to elucidate the electron beam induced dynamics of surface dislocations on ~ 4 nm × 6 nm sized Au (100) terraces located on top of hillock shaped Au at room temperature and 77 K at video rate (20 frames/s). At room temperature, very small terraces (< 4 × 5 atoms) sink into the lower terrace forming surface dislocations associated with a (5 × 1) surface reconstruction unit cell. This injection occurs provided that the number of atoms of the terrace fits the number of extra atoms required to form the surface dislocation. The surface dislocation consists of either 5 or 3 (Type I and Type II) hexagonally stacked atom rows. While the surface dislocations tend to reside near terrace edges, in ~ 20% of the video frames, the surface dislocation resides near the center of the terrace. The occurrence of Type I or Type II structures depends on the terrace width. DFT calculations show that Type I surface dislocations are more stable than Type II, for dislocations that do not span the entire terrace width, in agreement with observations. Surface dislocations are observed to flip by 90° during the experimental observations; the pathway and energy barrier (1.01 eV) for such flips is clarified through DFT calculations. At 77 K, no injections are observed, but surface dislocations do rarely form from an unreconstructed surface. In addition to dislocation flipping, multiple, dynamic dislocation configurations were observed in conjunction with terrace growth along the dislocation direction.

  2. Epidemic Wave Dynamics Attributable to Urban Community Structure: A Theoretical Characterization of Disease Transmission in a Large Network

    PubMed Central

    Eggo, Rosalind M; Lenczner, Michael

    2015-01-01

    Background Multiple waves of transmission during infectious disease epidemics represent a major public health challenge, but the ecological and behavioral drivers of epidemic resurgence are poorly understood. In theory, community structure—aggregation into highly intraconnected and loosely interconnected social groups—within human populations may lead to punctuated outbreaks as diseases progress from one community to the next. However, this explanation has been largely overlooked in favor of temporal shifts in environmental conditions and human behavior and because of the difficulties associated with estimating large-scale contact patterns. Objective The aim was to characterize naturally arising patterns of human contact that are capable of producing simulated epidemics with multiple wave structures. Methods We used an extensive dataset of proximal physical contacts between users of a public Wi-Fi Internet system to evaluate the epidemiological implications of an empirical urban contact network. We characterized the modularity (community structure) of the network and then estimated epidemic dynamics under a percolation-based model of infectious disease spread on the network. We classified simulated epidemics as multiwave using a novel metric and we identified network structures that were critical to the network’s ability to produce multiwave epidemics. Results We identified robust community structure in a large, empirical urban contact network from which multiwave epidemics may emerge naturally. This pattern was fueled by a special kind of insularity in which locally popular individuals were not the ones forging contacts with more distant social groups. Conclusions Our results suggest that ordinary contact patterns can produce multiwave epidemics at the scale of a single urban area without the temporal shifts that are usually assumed to be responsible. Understanding the role of community structure in epidemic dynamics allows officials to anticipate epidemic

  3. Design and Development of Layered Security: Future Enhancements and Directions in Transmission

    PubMed Central

    Shahzad, Aamir; Lee, Malrey; Kim, Suntae; Kim, Kangmin; Choi, Jae-Young; Cho, Younghwa; Lee, Keun-Kwang

    2016-01-01

    Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA) systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security issues, but due to insecure real-time protocol use and the reliance upon open protocols during Internet-based communication, these SCADA systems can still be compromised by security challenges. This study reviews the security challenges and issues that are commonly raised during SCADA/protocol transmissions and proposes a secure distributed-network protocol version 3 (DNP3) design, and the implementation of the security solution using a cryptography mechanism. Due to the insecurities found within SCADA protocols, the new development consists of a DNP3 protocol that has been designed as a part of the SCADA system, and the cryptographically derived security is deployed within the application layer as a part of the DNP3 stack. PMID:26751443

  4. Design and Development of Layered Security: Future Enhancements and Directions in Transmission.

    PubMed

    Shahzad, Aamir; Lee, Malrey; Kim, Suntae; Kim, Kangmin; Choi, Jae-Young; Cho, Younghwa; Lee, Keun-Kwang

    2016-01-01

    Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA) systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security issues, but due to insecure real-time protocol use and the reliance upon open protocols during Internet-based communication, these SCADA systems can still be compromised by security challenges. This study reviews the security challenges and issues that are commonly raised during SCADA/protocol transmissions and proposes a secure distributed-network protocol version 3 (DNP3) design, and the implementation of the security solution using a cryptography mechanism. Due to the insecurities found within SCADA protocols, the new development consists of a DNP3 protocol that has been designed as a part of the SCADA system, and the cryptographically derived security is deployed within the application layer as a part of the DNP3 stack. PMID:26751443

  5. Male circumcision and common sexually transmissible diseases in a developed nation setting.

    PubMed Central

    Donovan, B; Bassett, I; Bodsworth, N J

    1994-01-01

    OBJECTIVE--To determine whether the circumcision status of men affected their likelihood of acquiring sexually transmissible diseases (STDs). DESIGN--A cross-sectional study employing an anonymous questionnaire, clinical examination and type specific serology for herpes simplex virus type 2 (HSV-2). SETTING--A public STD clinic in Sydney, Australia. SUBJECTS--300 consecutive heterosexual male patients. MAIN OUTCOME MEASURES--Associations between circumcision status and past or present diagnoses of STDs including HSV-2 serology and clinical pattern of genital herpes. RESULTS--185 (62%) of the men were circumcised and they reported similar ages, education levels and lifetime partner numbers as men who were uncircumcised. There were no significant associations between the presence or absence of the male prepuce and the number diagnosed with genital herpes, genital warts and non-gonococcal urethritis. Men who were uncircumcised were no more likely to be seropositive for HSV-2 and reported symptomatic genital herpes outbreaks of the same frequency and severity as men who were circumcised. Gonorrhoea, syphilis and acute hepatitis B were reported too infrequently to reliably exclude any association with circumcision status. Human immunodeficiency virus infection (rare among heterosexual men in the clinic) was an exclusion criterion. CONCLUSIONS--From the findings of this study, circumcision of men has no significant effect on the incidence of common STDs in this developed nation setting. However, these findings may not necessarily extend to other setting where hygiene is poorer and the spectrum of common STDs is different. PMID:8001942

  6. Cable insulation development (1): Superconducting power transmission system development (2): Annual report for the period 1 October 1985-30 September 1986

    SciTech Connect

    Not Available

    1987-02-09

    Progress is reported for two projects, the development of a superconducting power transmission system and an ambient temperature high stress power cable. The objective of the superconducting power transmission cable program is to develop a system which is economical and technically attractive to the utility industry. Laboratory work in this project has extended to an outside test facility which represents an intermediate step between the laboratory scale and a full-scale system. Ambient temperature high stress cable development has involved development of a fully synthetic polyethylene or polypropylene dielectric tape for use as electrical insulation. 12 figs., 5 tabs.

  7. In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)

    SciTech Connect

    LaGrange, T B; Campbell, G H; Colvin, J D; King, W E; Browning, N D; Armstrong, M R; Reed, B W; Kim, J S; Stuart, B C

    2005-11-21

    The {alpha} to {beta} transition in pure Ti occurs mainly by a 'martensitic type' phase transformation. In such transformations, growth rates and interface velocities tend to be very large, on the order of 10{sup 3} m/s, making it difficult to observe the transformation experimentally. With thin films, it becomes even more difficult to observe, since the large surface augments the nucleation and transformation rates to levels that require nanosecond temporal resolution for experimental observations. The elucidation of the transformational mechanisms in these materials yearns for an apparatus that has both high spatial and temporal resolution. We have constructed such an instrument at LLNL (the dynamical transmission electron microscope or DTEM) that combines pulsed lasers systems and optical pump-probe techniques with a conventional TEM. We have used the DTEM to observe the transient events of the {alpha}-{beta} transformation in nanocrystalline Ti films via single shot diffraction patterns with 1.5 ns resolution. With pulsed, nanosecond laser irradiation (pump laser), the films were heated at an extreme rate of 10{sup 10} K/s. was observed At 500 ns after the initial pump laser hit, the HCP, alpha phase was almost completely transformed to the BCC, beta phase. Post-mortem investigations of the laser treated films revealed that substantial grain growth occurred and lath microstructure, containing no apparent dislocations. The lack of dislocations may indicate that the {alpha} to {beta} transformation may also proceed by a 'massive' type mechanism (short range diffusion).

  8. High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Hihath, Sahar; Santala, Melissa K.; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

    2016-03-01

    Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications.

  9. A Flexible Client-Driven 3DTV System for Real-Time Acquisition, Transmission, and Display of Dynamic Scenes

    NASA Astrophysics Data System (ADS)

    Cao, Xun; Liu, Yebin; Dai, Qionghai

    2008-12-01

    3D experience and free-viewpoint navigation are expected to be two essential features of next generation television. In this paper, we present a flexible 3DTV system in which multiview video streams are captured, compressed, transmitted, and finally converted to high-quality 3D video in real time. Our system consists of an [InlineEquation not available: see fulltext.] camera array, 16 producer PCs, a streaming server, multiple clients, and several autostereoscopic displays. The whole system is implemented over IP network to provide multiple users with interactive 2D/3D switching, viewpoint control, and synthesis for dynamic scenes. In our approach, multiple video streams are first captured by a synchronized camera array. Then, we adopt a lengthened-B-field and region of interest- (ROI-) based coding scheme to guarantee a seamless view switching for each user as well as saving per-user transmission bandwidth. Finally, a convenient rendering algorithm is used to synthesize a visually pleasing result by introducing a new metric called Clarity Degree (CD). Experiments on both synthetic and real-world data have verified the feasibility, flexibility, and good performance of our system.

  10. High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy.

    PubMed

    Hihath, Sahar; Santala, Melissa K; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

    2016-01-01

    Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications. PMID:26965073

  11. High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

    PubMed Central

    Hihath, Sahar; Santala, Melissa K.; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

    2016-01-01

    Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combination of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Our results allow for improved safety during laser ablation in manufacturing and medical applications. PMID:26965073

  12. High speed direct imaging of thin metal film ablation by movie-mode dynamic transmission electron microscopy

    DOE PAGESBeta

    Hihath, Sahar; Santala, Melissa K.; Cen, Xi; Campbell, Geoffrey; van Benthem, Klaus

    2016-03-11

    Obliteration of matter by pulsed laser beams is not only prevalent in science fiction movies, but finds numerous technological applications ranging from additive manufacturing over machining of micro- and nanostructured features to health care. Pulse lengths ranging from femtoseconds to nanoseconds are utilized at varying laser beam energies and pulse lengths, and enable the removal of nanometric volumes of material. While the mechanisms for removal of material by laser irradiation, i.e., laser ablation, are well understood on the micrometer length scale, it was previously impossible to directly observe obliteration processes on smaller scales due to experimental limitations for the combinationmore » of nanometer spatial and nanosecond temporal resolution. Here, we report the direct observation of metal thin film ablation from a solid substrate through dynamic transmission electron microscopy. Quantitative analysis reveals liquid-phase dewetting of the thin-film, followed by hydrodynamic sputtering of nano- to submicron sized metal droplets. We discovered unexpected fracturing of the substrate due to evolving thermal stresses. This study confirms that hydrodynamic sputtering remains a valid mechanism for droplet expulsion on the nanoscale, while irradiation induced stress fields represent limit laser processing of nanostructured materials. Ultimately, our results allow for improved safety during laser ablation in manufacturing and medical applications.« less

  13. Disease dynamics during wildlife translocations: disruptions to the host population and potential consequences for transmission in desert tortoise contact networks

    USGS Publications Warehouse

    Aiello, Christina M.; Nussear, Kenneth E.; Walde, Andrew D.; Esque, Todd C.; Emblidge, Patrick G.; Sah, Pratha; Bansal, S.; Hudson, Peter J.

    2014-01-01

    Wildlife managers consider animal translocation a means of increasing the viability of a local population. However, augmentation may disrupt existing resident disease dynamics and initiate an outbreak that would effectively offset any advantages the translocation may have achieved. This paper examines fundamental concepts of disease ecology and identifies the conditions that will increase the likelihood of a disease outbreak following translocation. We highlight the importance of susceptibility to infection, population size and population connectivity – a characteristic likely affected by translocation but not often considered in risk assessments – in estimating outbreak risk due to translocation. We then explore these features in a species of conservation concern often translocated in the presence of infectious disease, the Mojave Desert tortoise, and use data from experimental tortoise translocations to detect changes in population connectivity that may influence pathogen transmission. Preliminary analyses comparing contact networks inferred from spatial data at control and translocation plots and infection simulation results through these networks suggest increased outbreak risk following translocation due to dispersal-driven changes in contact frequency and network structure. We outline future research goals to test these concepts and aid managers in designing effective risk assessment and intervention strategies that will improve translocation success.

  14. High resolution transmission soft X-ray microscopy of deterioration products developed in large concrete dams

    PubMed

    Kurtis; Monteiro; Brown; Meyer-Ilse

    1999-12-01

    the FURNAS Dam in Minas Gerais, Brazil. Images of the ASR gel in sodium hydroxide indicated dissolution and repolymerization of the silicate into a less dense form, demonstrating the expansive nature of the gel when exposed to alkalis. In the calcium hydroxide solution, ASR gel, silica fume, and chemical grade silica gel each reacted with the calcium ions in solution to produce a calcium silicate hydrate precursor with a lathlike, branching morphology. The distinctive spherulitic microstructure formed during this reaction was identified as the 'sheaf of wheat' morphology, previously described in the literature. In addition, the development of the sheaf of wheat morphology was documented over time. These results suggest that of the cations studied in this investigation, it is the alkalis in concrete pore solution that produce the expansive ASR gel, while reaction with calcium ions does not result in expansion or damage to the concrete structure. More broadly, these results demonstrate the advantage of transmission soft X-ray microscopy for the study of the alkali-silica reaction, indicating the value of this technique for further studies in concrete technology. PMID:10594769

  15. Flight dynamics system software development environment (FDS/SDE) tutorial

    NASA Technical Reports Server (NTRS)

    Buell, John; Myers, Philip

    1986-01-01

    A sample development scenario using the Flight Dynamics System Software Development Environment (FDS/SDE) is presented. The SDE uses a menu-driven, fill-in-the-blanks format that provides online help at all steps, thus eliminating lengthy training and allowing immediate use of this new software development tool.

  16. [Population dynamics and development in the Caribbean].

    PubMed

    Boland, B

    1995-12-01

    The impact is examined of socioeconomic factors on Caribbean population dynamics. This work begins by describing the socioeconomic context of the late 1980s and early 1990s, under the influence of the economic changes and crises of the 1980s. The small size, openness, dependency, and lack of diversification of the Caribbean economies have made them vulnerable to external pressures. The Bahamas and Belize had economic growth rates exceeding 5% annually during 1981-90, but most of the countries had low or negative growth. Unemployment, poverty, the structural adjustment measures adopted in the mid-1980s, and declines in social spending exacerbated general economic conditions. In broad terms, the population situation of the Caribbean is marked by diversity of sizes and growth rates. A few countries oriented toward services and tourism had demographic growth rates exceeding 3%, while at least 7 had almost no growth or negative growth. Population growth rates reflected different combinations of natural increase and migration. Crude death rates ranged from around 5/1000 to 11/1000, except in Haiti, and all countries of the region except Haiti had life expectancies of 70 years or higher. Despite fertility decline, the average crude birth rate was still relatively high at 26/1000, and the rate of natural increase was 1.8% annually for the region. Nearly half of the regional population was under 15 or over 65 years old. The body of this work provides greater detail on mortality patterns, variations by sex, infant mortality, causes of death, and implications for policy. The discussion of fertility includes general patterns and trends, age specific fertility rates, contraceptive prevalence, levels of adolescent fertility and age factors in adolescent sexual behavior, characteristics of adolescent unions, contraceptive usage, health and social consequences of adolescent childbearing, and the search for solutions. The final section describes the magnitude and causes of

  17. Finite Element Development of Honeycomb Panel Configurations with Improved Transmission Loss

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Palumbo, Daniel L.; Klos, Jacob; Castle, William D.

    2006-01-01

    The higher stiffness-to-mass ratio of a honeycomb panel compared to a homogeneous panel results in a lower acoustic critical frequency. Above the critical frequency the panel flexural wave speed is acoustically fast and the structure becomes a more efficient radiator with associated lower sound transmission loss. Finite element models of honeycomb sandwich structures are presented featuring areas where the core is removed from the radiating face sheet disrupting the supersonic flexural and shear wave speeds that exist in the baseline honeycomb panel. These modified honeycomb panel structures exhibit improved transmission loss for a pre-defined diffuse field sound excitation. The models were validated by the sound transmission loss of honeycomb panels measured in the Structural Acoustic Loads and Transmission (SALT) facility at the NASA Langley Research Center. A honeycomb core panel configuration is presented exhibiting a transmission loss improvement of 3-11 dB compared to a honeycomb baseline panel over a frequency range from 170 Hz to 1000 Hz. The improved transmission loss panel configuration had a 5.1% increase in mass over the baseline honeycomb panel, and approximately twice the deflection when excited by a static force.

  18. Molecular assessment of Hepatozoon (Apicomplexa: Adeleorina) infections in wild canids and rodents from north Africa, with implications for transmission dynamics across taxonomic groups.

    PubMed

    Maia, João P; Alvares, Francisco; Boratyński, Zbyszek; Brito, José C; Leite, João V; Harris, D James

    2014-10-01

    Parasites play a major role in ecosystems, and understanding of host-parasite interactions is important for predicting parasite transmission dynamics and epidemiology. However, there is still a lack of knowledge about the distribution, diversity, and impact of parasites in wildlife, especially from remote areas. Hepatozoon is a genus of apicomplexan parasites that is transmitted by ingestion of infected arthropod vectors. However, alternative modes of transmission have been identified such as trophic transmission. Using the 18S rRNA gene as a marker, we provide an assessment of Hepatozoon prevalence in six wild canid and two rodent species collected between 2003 and 2012 from remote areas in North Africa. By combining this with other predator-prey systems in a phylogenetic framework, we investigate Hepatozoon transmission dynamics in distinct host taxa. Prevalence was high overall among host species (African jerboa Jaculus jaculus [17/47, 36%], greater Egyptian jerboa Jaculus orientalis [5/7, 71%], side-striped jackal Canis adustus [1/2, 50%], golden jackal Canis aureus [6/32, 18%], pale fox Vulpes pallida [14/28, 50%], Rüppell's fox Vulpes rueppellii [6/11, 55%], red fox Vulpes vulpes [8/16, 50%], and fennec fox Vulpes zerda [7/11, 42%]). Phylogenetic analysis showed further evidence of occasional transmission of Hepatozoon lineages from prey to canid predators, which seems to occur less frequently than in other predator-prey systems such as between snakes and lizards. Due to the complex nature of the Hepatozoon lifecycle (heteroxenous and vector-borne), future studies on these wild host species need to clarify the dynamics of alternative modes of Hepatozoon transmission and identify reservoir and definitive hosts in natural populations. We also detected putative Babesia spp. (Apicomplexa: Piroplasmida) infections in two canid species from this region, V. pallida (1/28) and V. zerda (1/11). PMID:25050803

  19. Developing Soil Models for Dynamic Impact Simulations

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Lyle, Karen H.; Jackson, Karen E.

    2009-01-01

    This paper describes fundamental soils characterization work performed at NASA Langley Research Center in support of the Subsonic Rotary Wing (SRW) Aeronautics Program and the Orion Landing System (LS) Advanced Development Program (ADP). LS-DYNA(Registered TradeMark)1 soil impact model development and test-analysis correlation results are presented for: (1) a 38-ft/s vertical drop test of a composite fuselage section, outfitted with four blocks of deployable energy absorbers (DEA), onto sand, and (2) a series of impact tests of a 1/2-scale geometric boilerplate Orion capsule onto soil. In addition, the paper will discuss LS-DYNA contact analysis at the soil/structure interface, methods used to estimate frictional forces, and the sensitivity of the model to density, moisture, and compaction.

  20. Fast adaptive OFDM-PON over single fiber loopback transmission using dynamic rate adaptation-based algorithm for channel performance improvement

    NASA Astrophysics Data System (ADS)

    Kartiwa, Iwa; Jung, Sang-Min; Hong, Moon-Ki; Han, Sang-Kook

    2014-03-01

    In this paper, we propose a novel fast adaptive approach that was applied to an OFDM-PON 20-km single fiber loopback transmission system to improve channel performance in term of stabilized BER below 2 × 10-3 and higher throughput beyond 10 Gb/s. The upstream transmission is performed through light source-seeded modulation using 1-GHz RSOA at the ONU. Experimental results indicated that the dynamic rate adaptation algorithm based on greedy Levin-Campello could be an effective solution to mitigate channel instability and data rate degradation caused by the Rayleigh back scattering effect and inefficient resource subcarrier allocation.

  1. Contributions of Dynamic Systems Theory to Cognitive Development

    PubMed Central

    Spencer, John P.; Austin, Andrew; Schutte, Anne R.

    2015-01-01

    This paper examines the contributions of dynamic systems theory to the field of cognitive development, focusing on modeling using dynamic neural fields. A brief overview highlights the contributions of dynamic systems theory and the central concepts of dynamic field theory (DFT). We then probe empirical predictions and findings generated by DFT around two examples—the DFT of infant perseverative reaching that explains the Piagetian A-not-B error, and the DFT of spatial memory that explain changes in spatial cognition in early development. A systematic review of the literature around these examples reveals that computational modeling is having an impact on empirical research in cognitive development; however, this impact does not extend to neural and clinical research. Moreover, there is a tendency for researchers to interpret models narrowly, anchoring them to specific tasks. We conclude on an optimistic note, encouraging both theoreticians and experimentalists to work toward a more theory-driven future. PMID:26052181

  2. Spontaneous activity in the developing gerbil auditory cortex in vivo involves GABAergic transmission

    PubMed Central

    Kotak, Vibhakar C.; Péndola, L. Martín; Rodríguez-Contreras, Adrián

    2012-01-01

    A salient feature of the developing brain is that spontaneous oscillations (SOs) and waves may influence the emergence of synaptic connections. Whilst gamma-amino butyric acid (GABA) produces depolarization and may support SOs in the neurons of developing rodents, it elicits hyperpolarization and diminishes SOs in developing gerbil auditory cortex (ACx). Therefore, we asked whether SOs exist in developing gerbil ACx in vivo and if GABAergic involvement can be manipulated. In vivo extracellular recordings in P3-5 ACx revealed SOs with longer burst durations and shorter inter-event intervals compared to ACx SOs in slices. ACx was then validated by gross anatomical features and lesions created at the in vivo recording site that corresponded with the electrophysiological coordinates of thalamorecipient ACx in slices. Further, NeuroVue Red, a lipophilic dye loaded at the in vivo recording sites, stained anatomically identifiable fiber tracks between the ACx and the auditory thalamus, medial geniculate body (MG). Separately, to chronically perturb GABAergic role in SOs, P2-5 pups were administered daily with GABAA receptor blocker, bicuculline (BIC). We then recorded from P14-17 ACx neurons in slices generated after hearing onset. ACx neurons from BIC-administered pups exhibited spontaneous action potentials in contrast to subthreshold synaptic potentials in neurons from sham-injected animals. Finally, to elucidate whether the gap junction blocker mefloquine (MFQ) previously shown to dampen ACx SOs in slices affected GABAergic transmission, MFQ was acutely applied in P3-5 slices while spontaneous inhibitory postsynaptic currents (sIPSCs) were recorded. Whereas MFQ increased the amplitude and frequency of sIPSCs in ACx neurons, the broad-spectrum gap junction blocker carbenoxolone decreased sIPSC amplitudes only. Together, we show that P2-5 gerbil ACx can endogenously generate SOs in vivo. Persistence of activity in ACx in P14-17 slices from pups administered with BIC at

  3. Studies on the dynamics of transmission of onchocerciasis in a Sudan-savanna area of North Cameroon V. What is a tolerable level of Annual Transmission Potential?

    PubMed

    Renz, A; Wenk, P; Anderson, J; Fuglsang, H

    1987-06-01

    The prevalence and intensity of infection with Onchocerca volvulus were assessed in population surveys in nine villages, situated at different distances from Simulium damnosum s.l. breeding sites. The prevalence varied from 48 to 89%, the arithmetic mean densities of microfilariae per skin snip were between 16 and 109, and severe ocular lesions were found in from 1 to 22% of patients. Annual Transmission Potentials (ATP) were measured for up to three years in the near vicinity of nine villages at several fly-catching sites. Weighted means of the ATP over the three years, and of the sojourn times of the human population, were calculated at three of the villages, where the prevalence of onchocerciasis was 51, 61 and 89%. An average ATP of 100 larvae or less in the head, thorax and abdomen of the flies was associated with an onchocerciasis prevalence of 50 to 60%, a mean microfilarial density below 40 microfilariae per skin-snip, less than 5% of ocular lesions, and no onchocercal blindness. This value might therefore be considered to be an indication of the level to which the transmission must be reduced in the savanna in order to prevent the occurrence of severe ocular lesions or blindness. It is lower than the present level accepted by the Onchocerciasis Control Programme in the Volta River Basin. PMID:3662668

  4. Malaria transmission dynamics in central Côte d'Ivoire: the influence of changing patterns of irrigated rice agriculture.

    PubMed

    Koudou, B G; Tano, Y; Doumbia, M; Nsanzabana, C; Cissé, G; Girardin, O; Dao, D; N'Goran, E K; Vounatsou, P; Bordmann, G; Keiser, J; Tanner, M; Utzinger, J

    2005-03-01

    The dynamics of malaria transmission was studied comparatively in the villages of Zatta and Tiemelekro, central Cote d'Ivoire, from February 2002 to August 2003. Prominent agroecosystems in these villages are irrigated rice growing and vegetable farming, respectively. Mosquitoes (Diptera: Culicidae) were collected on human bait at night and by pyrethrum knock-down spray sheet collections at four randomly selected sentinel sites in each village. In 2002, for a total of 96 man-nights per village, 7716 mosquitoes were collected in Zatta and 3308 in Tiemelekro. In 2003, with half the sampling effort, 859 and 2056 mosquitoes were collected in Zatta and Tiemelekro, respectively. Anopheles gambiae Giles s.l. was the predominant mosquito and the key malaria vector throughout, followed by An. funestus Giles. Anthropophily among adult female Anopheles exceeded 95% in both villages. Comparison between years revealed that the biting rate of An. gambiae s.l. in Zatta decreased several-fold from 49.3 bites per person per night (b/p/n) in 2002 to 7.9 b/p/n in 2003 (likelihood ratio test (LRT) = 1072.66; P < 0.001). Although the biting rate remained fairly constant in Tiemelekro, the difference between years was significant (16.1 vs. 18.2 b/p/n; LRT = 148.06; P < 0.001). These observations were paralleled by a marked decrease in the infective rate of An. gambiae s.l. in Zatta (4.6-1.2%), and an increase in Tiemelekro (3.1-7.6%). Meanwhile, the entomological inoculation rate of An. gambiae s.l. decreased 21-fold in Zatta, from 789 to 38 infective bites per person per year (ib/p/y), whereas it remained high in Tiemelekro (233 vs. 342 ib/p/y). The interruption of irrigated rice growing in Zatta in 2003, consequential to a farmers' conflict over land, might be the underlying cause for the significant reduction in malaria transmission, whereas more stable conditions occurred in Tiemelekro. PMID:15752174

  5. SSME structural dynamic model development, phase 2

    NASA Technical Reports Server (NTRS)

    Foley, M. J.; Wilson, V. L.

    1985-01-01

    A set of test correlated mathematical models of the SSME High Pressure Oxygen Turbopump (HPOTP) housing and rotor assembly was produced. New analysis methods within the EISI/EAL and SPAR systems were investigated and runstreams for future use were developed. The LOX pump models have undergone extensive modification since the first phase of this effort was completed. The rotor assembly from the original model was abandoned and a new, more detailed model constructed. A description of the new rotor math model is presented. Also, the pump housing model was continually modified as additional test data have become available. This model is documented along with measured test results. Many of the more advanced features of the EAL/SPAR finite element analysis system were exercised. These included the cyclic symmetry option, the macro-element procedures, and the fluid analysis capability. In addition, a new tool was developed that allows an automated analysis of a disjoint structure in terms of its component modes. A complete description of the implementation of the Craig-Bampton method is given along with two worked examples.

  6. Emission and transmission tomography systems to be developed for the future needs of Jules Horowitz material testing reactor

    NASA Astrophysics Data System (ADS)

    Kotiluoto, Petri; Wasastjerna, Frej; Kekki, Tommi; Sipilä, Heikki; Banzuzi, Kukka; Kinnunen, Petri; Heikinheimo, Liisa

    2009-08-01

    The new 100 MW Jules Horowitz material testing reactor will be built in Cadarache, France. It will support, for instance, research on new types of innovative nuclear fuel. As a Finnish in-kind contribution, 3D emission and transmission tomography equipment will be delivered for both the reactor and the active component storage pool. The image reconstruction of activities inside the used nuclear fuel will be based on gamma spectrometry measurements. A new type of underwater digital X-ray linear detector array is under development for transmission imaging, based on GaAs and direct conversion of X-rays into an electrical signal. A shared collimator will be used for both emission and transmission measurements. Some preliminary design has been performed. For the current design, the expected gamma spectrometric response of a typical high-purity germanium detector has been simulated with MCNP for minimum and maximum source activities (specified by CEA) to be measured in future.

  7. Socio-Demographics and the Development of Malaria Elimination Strategies in the Low Transmission Setting

    PubMed Central

    Chuquiyauri, Raul; Paredes, Maribel; Peñataro, Pablo; Torres, Sonia; Marin, Silvia; Tenorio, Alexander; Brouwer, Kimberly C.; Abeles, Shira; Llanos-Cuentas, Alejandro; Gilman, Robert H.; Kosek, Margaret; Vinetz, Joseph M.

    2011-01-01

    This analysis presents a comprehensive description of malaria burden and risk factors in Peruvian Amazon villages where malaria transmission is hypoendemic. More than 9,000 subjects were studied in contrasting village settings within the Department of Loreto, Peru, where most malaria occurs in the country. Plasmodium vivax is responsible for more than 75% of malaria cases; severe disease from any form of malaria is uncommon and death rare. The association between lifetime malaria episodes and individual and household covariates was studied using polychotomous logistic regression analysis, assessing effects on odds of some vs. no lifetime malaria episodes. Malaria morbidity during lifetime was strongly associated with age, logging, farming, travel history, and living with a logger or agriculturist. Select groups of adults, particularly loggers and agriculturists acquire multiple malaria infections in transmission settings outside of the main domicile, and may be mobile human reservoirs by which malaria parasites move within and between micro-regions within malaria endemic settings. For example, such individuals might well be reservoirs of transmission by introducing or reintroducing malaria into their home villages and their own households, depending on vector ecology and the local village setting. Therefore, socio-demographic studies can identify people with the epidemiological characteristic of transmission risk, and these individuals would be prime targets against which to deploy transmission blocking strategies along with insecticide treated bednets and chemoprophylaxis. PMID:22100446

  8. Dynamic effects of TNF-α on synaptic transmission in mice over time following sciatic nerve chronic constriction injury

    PubMed Central

    Zhang, Hongmei; Zhang, Haijun

    2013-01-01

    Nerve injury-induced central sensitization can manifest as an increase in excitatory synaptic transmission and/or as a decrease in inhibitory synaptic transmission in spinal dorsal horn neurons. Cytokines such as tumor necrosis factor-α (TNF-α) are induced in the spinal cord under various injury conditions and contribute to neuropathic pain. In this study we examined the effect of TNF-α in modulating excitatory and inhibitory synaptic input to spinal substantia gelatinosa (SG) neurons over time in mice following chronic constriction injury (CCI) of the sciatic nerve. Whole cell patch-clamp studies from SG neurons showed that TNF-α enhanced overall excitability of the spinal cord early in time following nerve injury 3 days after CCI compared with that in sham control mice. In contrast, the effects of TNF were blunted 14 days after CCI in nerve-injured mice compared with sham surgery mice. Immunohistochemical staining showed that the expression of TNF-α receptor 1 (TNFR1) was increased at 3 days but decreased at 14 days following CCI in the ipsilateral vs. the contralateral spinal cord dorsal horn. These results suggest that TNF-α acting at TNFR1 is important in the development of neuropathic pain by facilitating excitatory synaptic signaling in the acute phases after nerve injury but has a reduced effect on spinal neuron signaling in the later phases of nerve injury-induced pain. Failure of the facilatory effects of TNF-α on excitatory synaptic signaling in the dorsal horn to resolve following nerve injury may be an important component in the transition between acute and chronic pain conditions. PMID:23864372

  9. The transmission of Mycobacterium tuberculosis in high burden settings.

    PubMed

    Yates, Tom A; Khan, Palwasha Y; Knight, Gwenan M; Taylor, Jonathon G; McHugh, Timothy D; Lipman, Marc; White, Richard G; Cohen, Ted; Cobelens, Frank G; Wood, Robin; Moore, David A J; Abubakar, Ibrahim

    2016-02-01

    Unacceptable levels of Mycobacterium tuberculosis transmission are noted in high burden settings and a renewed focus on reducing person-to-person transmission in these communities is needed. We review recent developments in the understanding of airborne transmission. We outline approaches to measure transmission in populations and trials and describe the Wells-Riley equation, which is used to estimate transmission risk in indoor spaces. Present research priorities include the identification of effective strategies for tuberculosis infection control, improved understanding of where transmission occurs and the transmissibility of drug-resistant strains, and estimates of the effect of HIV and antiretroviral therapy on transmission dynamics. When research is planned and interventions are designed to interrupt transmission, resource constraints that are common in high burden settings-including shortages of health-care workers-must be considered. PMID:26867464

  10. Understanding Dynamics of Information Transmission in Drosophila melanogaster Using a Statistical Modeling Framework for Longitudinal Network Data (the RSiena Package)

    PubMed Central

    Pasquaretta, Cristian; Klenschi, Elizabeth; Pansanel, Jérôme; Battesti, Marine; Mery, Frederic; Sueur, Cédric

    2016-01-01

    Social learning – the transmission of behaviors through observation or interaction with conspecifics – can be viewed as a decision-making process driven by interactions among individuals. Animal group structures change over time and interactions among individuals occur in particular orders that may be repeated following specific patterns, change in their nature, or disappear completely. Here we used a stochastic actor-oriented model built using the RSiena package in R to estimate individual behaviors and their changes through time, by analyzing the dynamic of the interaction network of the fruit fly Drosophila melanogaster during social learning experiments. In particular, we re-analyzed an experimental dataset where uninformed flies, left free to interact with informed ones, acquired and later used information about oviposition site choice obtained by social interactions. We estimated the degree to which the uninformed flies had successfully acquired the information carried by informed individuals using the proportion of eggs laid by uninformed flies on the medium their conspecifics had been trained to favor. Regardless of the degree of information acquisition measured in uninformed individuals, they always received and started interactions more frequently than informed ones did. However, information was efficiently transmitted (i.e., uninformed flies predominantly laid eggs on the same medium informed ones had learn to prefer) only when the difference in contacts sent between the two fly types was small. Interestingly, we found that the degree of reciprocation, the tendency of individuals to form mutual connections between each other, strongly affected oviposition site choice in uninformed flies. This work highlights the great potential of RSiena and its utility in the studies of interaction networks among non-human animals. PMID:27148146

  11. Understanding Dynamics of Information Transmission in Drosophila melanogaster Using a Statistical Modeling Framework for Longitudinal Network Data (the RSiena Package).

    PubMed

    Pasquaretta, Cristian; Klenschi, Elizabeth; Pansanel, Jérôme; Battesti, Marine; Mery, Frederic; Sueur, Cédric

    2016-01-01

    Social learning - the transmission of behaviors through observation or interaction with conspecifics - can be viewed as a decision-making process driven by interactions among individuals. Animal group structures change over time and interactions among individuals occur in particular orders that may be repeated following specific patterns, change in their nature, or disappear completely. Here we used a stochastic actor-oriented model built using the RSiena package in R to estimate individual behaviors and their changes through time, by analyzing the dynamic of the interaction network of the fruit fly Drosophila melanogaster during social learning experiments. In particular, we re-analyzed an experimental dataset where uninformed flies, left free to interact with informed ones, acquired and later used information about oviposition site choice obtained by social interactions. We estimated the degree to which the uninformed flies had successfully acquired the information carried by informed individuals using the proportion of eggs laid by uninformed flies on the medium their conspecifics had been trained to favor. Regardless of the degree of information acquisition measured in uninformed individuals, they always received and started interactions more frequently than informed ones did. However, information was efficiently transmitted (i.e., uninformed flies predominantly laid eggs on the same medium informed ones had learn to prefer) only when the difference in contacts sent between the two fly types was small. Interestingly, we found that the degree of reciprocation, the tendency of individuals to form mutual connections between each other, strongly affected oviposition site choice in uninformed flies. This work highlights the great potential of RSiena and its utility in the studies of interaction networks among non-human animals. PMID:27148146

  12. Developing Generic Dynamic Models for the 2030 Eastern Interconnection Grid

    SciTech Connect

    Kou, Gefei; Hadley, Stanton W; Markham, Penn N; Liu, Yilu

    2013-12-01

    The Eastern Interconnection Planning Collaborative (EIPC) has built three major power flow cases for the 2030 Eastern Interconnection (EI) based on various levels of energy/environmental policy conditions, technology advances, and load growth. Using the power flow cases, this report documents the process of developing the generic 2030 dynamic models using typical dynamic parameters. The constructed model was validated indirectly using the synchronized phasor measurements by removing the wind generation temporarily.

  13. Prospective Teachers' Experiences in Developing Lessons with Dynamic Mathematics Software

    ERIC Educational Resources Information Center

    Haciomeroglu, Erhan Selcuk; Bu, Lingguo; Schoen, Robert C.; Hohenwarter, Markus

    2011-01-01

    This study sought to examine the development of prospective secondary mathematics teachers' Technological Pedagogical Content Knowledge as they worked individually and in small groups to develop and present lessons with dynamic mathematics software. In a three-semester long study, data were collected from 68 prospective secondary mathematics…

  14. Computational fluid dynamics development and validation at Bell Helicopter

    NASA Astrophysics Data System (ADS)

    Narramore, J. C.

    1995-08-01

    An overview of the development of the Computational Fluid Dynamics (CFD) methodology at Bell Helicopter Textron is given. As new technologies have been developed their functionality has been assessed by their ability to reproduce wind tunnel measurements in a timely manner. Examples of some of these correlation study results are provided.

  15. Dynamic Visual Perception and Reading Development in Chinese School Children

    ERIC Educational Resources Information Center

    Meng, Xiangzhi; Cheng-Lai, Alice; Zeng, Biao; Stein, John F.; Zhou, Xiaolin

    2011-01-01

    The development of reading skills may depend to a certain extent on the development of basic visual perception. The magnocellular theory of developmental dyslexia assumes that deficits in the magnocellular pathway, indicated by less sensitivity in perceiving dynamic sensory stimuli, are responsible for a proportion of reading difficulties…

  16. Simulating Poverty and Inequality Dynamics in Developing Countries

    ERIC Educational Resources Information Center

    Ansoms, An; Geenen, Sara

    2012-01-01

    This article considers how the simulation game of DEVELOPMENT MONOPOLY provides insight into poverty and inequality dynamics in a development context. It first discusses how the game is rooted in theoretical and conceptual frameworks on poverty and inequality. Subsequently, it reflects on selected playing experiences, with special focus on the…

  17. Product assurance policies and procedures for flight dynamics software development

    NASA Technical Reports Server (NTRS)

    Perry, Sandra; Jordan, Leon; Decker, William; Page, Gerald; Mcgarry, Frank E.; Valett, Jon

    1987-01-01

    The product assurance policies and procedures necessary to support flight dynamics software development projects for Goddard Space Flight Center are presented. The quality assurance and configuration management methods and tools for each phase of the software development life cycles are described, from requirements analysis through acceptance testing; maintenance and operation are not addressed.

  18. Seasonal and Regional Dynamics of M. ulcerans Transmission in Environmental Context: Deciphering the Role of Water Bugs as Hosts and Vectors

    PubMed Central

    Marion, Estelle; Eyangoh, Sara; Yeramian, Edouard; Doannio, Julien; Landier, Jordi; Aubry, Jacques; Fontanet, Arnaud; Rogier, Christophe; Cassisa, Viviane; Cottin, Jane; Marot, Agnès; Eveillard, Matthieu; Kamdem, Yannick; Legras, Pierre; Deshayes, Caroline; Saint-André, Jean-Paul; Marsollier, Laurent

    2010-01-01

    Background Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. Various modes of transmission have been suspected for this disease, with no general consensus acceptance for any of them up to now. Since laboratory models demonstrated the ability of water bugs to transmit M. ulcerans, a particular attention is focused on the transmission of the bacilli by water bugs as hosts and vectors. However, it is only through detailed knowledge of the biodiversity and ecology of water bugs that the importance of this mode of transmission can be fully assessed. It is the objective of the work here to decipher the role of water bugs in M. ulcerans ecology and transmission, based on large-scale field studies. Methodology/Principal Findings The distribution of M. ulcerans-hosting water bugs was monitored on previously unprecedented time and space scales: a total of 7,407 water bugs, belonging to large number of different families, were collected over one year, in Buruli ulcer endemic and non endemic areas in central Cameroon. This study demonstrated the presence of M. ulcerans in insect saliva. In addition, the field results provided a full picture of the ecology of transmission in terms of biodiversity and detailed specification of seasonal and regional dynamics, with large temporal heterogeneity in the insect tissue colonization rate and detection of M. ulcerans only in water bug tissues collected in Buruli ulcer endemic areas. Conclusion/Significance The large-scale detection of bacilli in saliva of biting water bugs gives enhanced weight to their role in M. ulcerans transmission. On practical grounds, beyond the ecological interest, the results concerning seasonal and regional dynamics can provide an efficient tool in the hands of sanitary authorities to monitor environmental risks associated with Buruli ulcer. PMID:20625552

  19. MO-A-BRD-01: An Investigation of the Dynamic Response of a Novel Acousto-Optic Liquid Crystal Detector for Full-Field Transmission Ultrasound Breast Imaging

    SciTech Connect

    Rosenfield, J.R.; La Riviere, P.J.; Sandhu, J.S.

    2014-06-15

    Purpose: To characterize the dynamic response of a novel acousto-optic (AO) liquid crystal detector for high-resolution transmission ultrasound breast imaging. Transient and steady-state lesion contrast were investigated to identify optimal transducer settings for our prototype imaging system consistent with the FDA limits of 1 W/cm{sup 2} and 50 J/cm{sup 2} on the incident acoustic intensity and the transmitted acoustic energy flux density. Methods: We have developed a full-field transmission ultrasound breast imaging system that uses monochromatic plane-wave illumination to acquire projection images of the compressed breast. The acoustic intensity transmitted through the breast is converted into a visual image by a proprietary liquid crystal detector operating on the basis of the AO effect. The dynamic response of the AO detector in the absence of an imaged breast was recorded by a CCD camera as a function of the acoustic field intensity and the detector exposure time. Additionally, a stereotactic needle biopsy breast phantom was used to investigate the change in opaque lesion contrast with increasing exposure time for a range of incident acoustic field intensities. Results: Using transducer voltages between 0.3 V and 0.8 V and exposure times of 3 minutes, a unique one-to-one mapping of incident acoustic intensity to steady-state optical brightness in the AO detector was observed. A transfer curve mapping acoustic intensity to steady-state optical brightness shows a high-contrast region analogous to the linear portion of the Hurter-Driffield curves of radiography. Using transducer voltages between 1 V and 1.75 V and exposure times of 90 s, the lesion contrast study demonstrated increasing lesion contrast with increasing breast exposure time and acoustic field intensity. Lesion-to-background contrast on the order of 0.80 was observed. Conclusion: Maximal lesion contrast in our prototype system can be obtained using the highest acoustic field intensity and the

  20. Solar dynamic power system development for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The development of a solar dynamic electric power generation system as part of the Space Station Freedom Program is documented. The solar dynamic power system includes a solar concentrator, which collects sunlight; a receiver, which accepts and stores the concentrated solar energy and transfers this energy to a gas; a Brayton turbine, alternator, and compressor unit, which generates electric power; and a radiator, which rejects waste heat. Solar dynamic systems have greater efficiency and lower maintenance costs than photovoltaic systems and are being considered for future growth of Space Station Freedom. Solar dynamic development managed by the NASA Lewis Research Center from 1986 to Feb. 1991 is covered. It summarizes technology and hardware development, describes 'lessons learned', and, through an extensive bibliography, serves as a source list of documents that provide details of the design and analytic results achieved. It was prepared by the staff of the Solar Dynamic Power System Branch at the NASA Lewis Research Center in Cleveland, Ohio. The report includes results from the prime contractor as well as from in-house efforts, university grants, and other contracts. Also included are the writers' opinions on the best way to proceed technically and programmatically with solar dynamic efforts in the future, on the basis of their experiences in this program.

  1. Rotorcraft transmissions

    NASA Technical Reports Server (NTRS)

    Coy, John J.

    1990-01-01

    Highlighted here is that portion of the Lewis Research Center's helicopter propulsion systems program that deals with drive train technology and the related mechanical components. The major goals of the program are to increase life, reliability, and maintainability, to reduce weight, noise, and vibration, and to maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development, followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented.

  2. Modulation of GABAergic transmission in development and neurodevelopmental disorders: investigating physiology and pathology to gain therapeutic perspectives

    PubMed Central

    Deidda, Gabriele; Bozarth, Ignacio F.; Cancedda, Laura

    2014-01-01

    During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis. The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions. PMID:24904277

  3. Role of vaccination-induced immunity and antigenic distance in the transmission dynamics of highly pathogenic avian influenza H5N1.

    PubMed

    Sitaras, Ioannis; Rousou, Xanthoula; Kalthoff, Donata; Beer, Martin; Peeters, Ben; de Jong, Mart C M

    2016-01-01

    Highly pathogenic avian influenza (HPAI) H5N1 epidemics in poultry cause huge economic losses as well as sporadic human morbidity and mortality. Vaccination in poultry has often been reported as being ineffective in preventing transmission and as a potential driving force in the selection of immune escape mutants. We conducted transmission experiments to evaluate the transmission dynamics of HPAI H5N1 strains in chickens vaccinated with high and low doses of immune escape mutants we have previously selected, and analysed the data using mathematical models. Remarkably, we demonstrate that the effect of antigenic distances between the vaccine and challenge strains used in this study is too small to influence the transmission dynamics of the strains used. This is because the effect of a sufficient vaccine dose on antibody levels against the challenge viruses is large enough to compensate for any decrease in antibody titres due to antigenic differences between vaccine and challenge strains. Our results show that at least under experimental conditions, vaccination will remain effective even after antigenic changes as may be caused by the initial selection in vaccinated birds. PMID:26763336

  4. The potential for sexual transmission to compromise control of Ebola virus outbreaks.

    PubMed

    Vinson, John E; Drake, John M; Rohani, Pejman; Park, Andrew W

    2016-06-01

    Recent evidence suggests that sexual contact may give rise to transmission of Ebola virus long after infection has been cleared from blood. We develop a simple mathematical model that incorporates contact transmission and sexual transmission parametrized from data relating to the 2013-2015 West African Ebola epidemic. The model explores scenarios where contact transmission is reduced following infection events, capturing behaviour change, and quantifies how these actions reducing transmission may be compromised by sexual transmission in terms of increasing likelihood, size and duration of outbreaks. We characterize the extent to which sexual transmission operates in terms of the probability of initial infection resolving to sexual infectiousness and the sexual transmission rate, and relate these parameters to the overall case burden. We find that sexual transmission can have large effects on epidemic dynamics (increasing attack ratios from 25% in scenarios without sexual transmission but with contact-transmission-reducing behaviour, up to 80% in equivalent scenarios with sexual transmission). PMID:27277951

  5. DEVELOPMENT OF AN INSPECTION PLATFORM AND A SUITE OF SENSORS FOR ASSESSING CORROSION AND MECHANICAL DAMAGE ON UNPIGGABLE TRANSMISSION MAINS

    SciTech Connect

    George C. Vradis; William Leary

    2004-03-01

    The National Energy Technology Laboratory of the US Department of Energy (under Award DE-FC26-02NT41645) and the NYSEARCH Committee of the Northeast Gas Association (previous the New York Gas Group), have sponsored research to develop a robotic pipeline inspection system capable of navigation through the typical physical and operational obstacles that make transmission and distribution pipelines unpiggable. The research contractors, Foster-Miller and GE Oil & Gas (PII North America) have performed an engineering study and developed a conceptual design that meets all the requirements for navigating and inspecting unpiggable transmission pipelines. Based on Foster-Miller's previous efforts developing the Pipe Mouse robot, the RoboScan inspection robot (Figure ES-1) meets the navigational and physical challenges of unpiggable pipelines through an innovative modular platform design, segmented MFL inspection modules and improvements to the inter-module coupling design.

  6. Estimated health and economic impact of quadrivalent HPV (types 6/11/16/18) vaccination in Brazil using a transmission dynamic model

    PubMed Central

    2012-01-01

    Background Cervical cancer is the second most common cancer among women in Brazil. We examined the health and economic impacts of quadrivalent HPV vaccination in Brazil. Methods We adapted a previously developed transmission dynamic model to estimate the effectiveness of HPV vaccination on cervical cancer, cervical intraepithelial neoplasia grades 2 and 3 (CIN2/3), CIN1, and genital warts. We evaluated following vaccination strategies: routine vaccination of 12-year-old girls and routine vaccination in combination with a catch-up vaccination of 12 to 26-year-old women. Results The model projected that the vaccination would reduce the incidence rates of HPV 6/11/16/18-related cervical cancer, CIN2/3, CIN1, and female genital warts by 94% to 98% at year 100. Routine vaccination in combination with a catch-up vaccination could prevent approximately 163,000 cases of cervical cancer, 48,000 deaths from cervical cancer, 2.3 million cases of CIN2/3, and 11.4 million genital warts in the next 50 years. The incremental cost-effectiveness ratios for female vaccination strategies ranged from R$350 to R$720 (US$219 to US$450) per quality-adjusted life year (QALY) gained. Conclusions Our study demonstrates that quadrivalent HPV female vaccination can be a cost-effective public health intervention that can substantially reduce the burden of cervical diseases and genital warts in Brazil. PMID:23046886

  7. Design and dynamic simulation of a fixed pitch 56 kW wind turbine drive train with a continuously variable transmission

    NASA Technical Reports Server (NTRS)

    Gallo, C.; Kasuba, R.; Pintz, A.; Spring, J.

    1986-01-01

    The dynamic analysis of a horizontal axis fixed pitch wind turbine generator (WTG) rated at 56 kW is discussed. A mechanical Continuously Variable Transmission (CVT) was incorporated in the drive train to provide variable speed operation capability. One goal of the dynamic analysis was to determine if variable speed operation, by means of a mechanical CVT, is capable of capturing the transient power in the WTG/wind environment. Another goal was to determine the extent of power regulation possible with CVT operation.

  8. Application of Serological Tools and Spatial Analysis to Investigate Malaria Transmission Dynamics in Highland Areas of Southwest Uganda

    PubMed Central

    Lynch, Caroline A.; Cook, Jackie; Nanyunja, Sarah; Bruce, Jane; Bhasin, Amit; Drakeley, Chris; Roper, Cally; Pearce, Richard; Rwakimari, John B.; Abeku, Tarekegn A.; Corran, Patrick; Cox, Jonathan

    2016-01-01

    Serological markers, combined with spatial analysis, offer a comparatively more sensitive means by which to measure and detect foci of malaria transmission in highland areas than traditional malariometric indicators. Plasmodium falciparum parasite prevalence, seroprevalence, and seroconversion rate to P. falciparum merozoite surface protein-119 (MSP-119) were measured in a cross-sectional survey to determine differences in transmission between altitudinal strata. Clusters of P. falciparum parasite prevalence and high antibody responses to MSP-119 were detected and compared. Results show that P. falciparum prevalence and seroprevalence generally decreased with increasing altitude. However, transmission was heterogeneous with hotspots of prevalence and/or seroprevalence detected in both highland and highland fringe altitudes, including a serological hotspot at 2,200 m. Results demonstrate that seroprevalence can be used as an additional tool to identify hotspots of malaria transmission that might be difficult to detect using traditional cross-sectional parasite surveys or through vector studies. Our study findings identify ways in which malaria prevention and control can be more effectively targeted in highland or low transmission areas via serological measures. These tools will become increasingly important for countries with an elimination agenda and/or where malaria transmission is becoming patchy and focal, but receptivity to malaria transmission remains high. PMID:27022156

  9. Application of Serological Tools and Spatial Analysis to Investigate Malaria Transmission Dynamics in Highland Areas of Southwest Uganda.

    PubMed

    Lynch, Caroline A; Cook, Jackie; Nanyunja, Sarah; Bruce, Jane; Bhasin, Amit; Drakeley, Chris; Roper, Cally; Pearce, Richard; Rwakimari, John B; Abeku, Tarekegn A; Corran, Patrick; Cox, Jonathan

    2016-06-01

    Serological markers, combined with spatial analysis, offer a comparatively more sensitive means by which to measure and detect foci of malaria transmission in highland areas than traditional malariometric indicators. Plasmodium falciparum parasite prevalence, seroprevalence, and seroconversion rate to P. falciparum merozoite surface protein-119 (MSP-119) were measured in a cross-sectional survey to determine differences in transmission between altitudinal strata. Clusters of P. falciparum parasite prevalence and high antibody responses to MSP-119 were detected and compared. Results show that P. falciparum prevalence and seroprevalence generally decreased with increasing altitude. However, transmission was heterogeneous with hotspots of prevalence and/or seroprevalence detected in both highland and highland fringe altitudes, including a serological hotspot at 2,200 m. Results demonstrate that seroprevalence can be used as an additional tool to identify hotspots of malaria transmission that might be difficult to detect using traditional cross-sectional parasite surveys or through vector studies. Our study findings identify ways in which malaria prevention and control can be more effectively targeted in highland or low transmission areas via serological measures. These tools will become increasingly important for countries with an elimination agenda and/or where malaria transmission is becoming patchy and focal, but receptivity to malaria transmission remains high. PMID:27022156

  10. Peroxisome dynamics during development of the fungus Podospora anserina.

    PubMed

    Takano-Rojas, Harumi; Zickler, Denise; Peraza-Reyes, Leonardo

    2016-01-01

    Peroxisomes are versatile and dynamic organelles that are required for the development of diverse eukaryotic organisms. We demonstrated previously that in the fungus Podospora anserina different peroxisomal functions are required at distinct stages of sexual development, including the initiation and progression of meiocyte (ascus) development and the differentiation and germination of sexual spores (ascospores). Peroxisome assembly during these processes relies on the differential activity of the protein machinery that drives the import of proteins into the organelle, indicating a complex developmental regulation of peroxisome formation and activity. Here we demonstrate that peroxisome dynamics is also highly regulated during development. We show that peroxisomes in P. anserina are highly dynamic and respond to metabolic and environmental cues by undergoing changes in size, morphology and number. In addition, peroxisomes of vegetative and sexual cell types are structurally different. During sexual development peroxisome number increases at two stages: at early ascus differentiation and during ascospore formation. These processes are accompanied by changes in peroxisome structure and distribution, which include a cell-polarized concentration of peroxisomes at the beginning of ascus development, as well as a morphological transition from predominantly spherical to elongated shapes at the end of the first meiotic division. Further, the mostly tubular peroxisomes present from second meiotic division to early ascospore formation again become rounded during ascospore differentiation. Ultimately the number of peroxisomes dramatically decreases upon ascospore maturation. Our results reveal a precise regulation of peroxisome dynamics during sexual development and suggest that peroxisome constitution and function during development is defined by the coordinated regulation of the proteins that control peroxisome assembly and dynamics. PMID:26908647

  11. Quantifying Transmission Investment in Malaria Parasites

    PubMed Central

    Greischar, Megan A.; Mideo, Nicole; Read, Andrew F.; Bjørnstad, Ottar N.

    2016-01-01

    Many microparasites infect new hosts with specialized life stages, requiring a subset of the parasite population to forgo proliferation and develop into transmission forms. Transmission stage production influences infectivity, host exploitation, and the impact of medical interventions like drug treatment. Predicting how parasites will respond to public health efforts on both epidemiological and evolutionary timescales requires understanding transmission strategies. These strategies can rarely be observed directly and must typically be inferred from infection dynamics. Using malaria as a case study, we test previously described methods for inferring transmission stage investment against simulated data generated with a model of within-host infection dynamics, where the true transmission investment is known. We show that existing methods are inadequate and potentially very misleading. The key difficulty lies in separating transmission stages produced by different generations of parasites. We develop a new approach that performs much better on simulated data. Applying this approach to real data from mice infected with a single Plasmodium chabaudi strain, we estimate that transmission investment varies from zero to 20%, with evidence for variable investment over time in some hosts, but not others. These patterns suggest that, even in experimental infections where host genetics and other environmental factors are controlled, parasites may exhibit remarkably different patterns of transmission investment. PMID:26890485

  12. Quantifying Transmission Investment in Malaria Parasites.

    PubMed

    Greischar, Megan A; Mideo, Nicole; Read, Andrew F; Bjørnstad, Ottar N

    2016-02-01

    Many microparasites infect new hosts with specialized life stages, requiring a subset of the parasite population to forgo proliferation and develop into transmission forms. Transmission stage production influences infectivity, host exploitation, and the impact of medical interventions like drug treatment. Predicting how parasites will respond to public health efforts on both epidemiological and evolutionary timescales requires understanding transmission strategies. These strategies can rarely be observed directly and must typically be inferred from infection dynamics. Using malaria as a case study, we test previously described methods for inferring transmission stage investment against simulated data generated with a model of within-host infection dynamics, where the true transmission investment is known. We show that existing methods are inadequate and potentially very misleading. The key difficulty lies in separating transmission stages produced by different generations of parasites. We develop a new approach that performs much better on simulated data. Applying this approach to real data from mice infected with a single Plasmodium chabaudi strain, we estimate that transmission investment varies from zero to 20%, with evidence for variable investment over time in some hosts, but not others. These patterns suggest that, even in experimental infections where host genetics and other environmental factors are controlled, parasites may exhibit remarkably different patterns of transmission investment. PMID:26890485

  13. Development of a Laboratory Synchrophasor Network and an Application to Estimate Transmission Line Parameters in Real Time

    NASA Astrophysics Data System (ADS)

    Almiron Bonnin, Rubens Eduardo

    The development of an experimental synchrophasors network and application of synchrophasors for real-time transmission line parameter monitoring are presented in this thesis. In the laboratory setup, a power system is simulated in a RTDS real-time digital simulator, and the simulated voltages and currents are input to hardware phasor measurement units (PMUs) through the analog outputs of the simulator. Time synchronizing signals for the PMU devices are supplied from a common GPS clock. The real time data collected from PMUs are sent to a phasor data concentrator (PDC) through Ethernet using the TCP/IP protocol. A real-time transmission line parameter monitoring application program that uses the synchrophasor data provided by the PDC is implemented and validated. The experimental synchrophasor network developed in this thesis is expected to be used in research on synchrophasor applications as well as in graduate and undergraduate teaching.

  14. Reduced forebrain serotonin transmission is causally involved in the development of compulsive cocaine seeking in rats.

    PubMed

    Pelloux, Yann; Dilleen, Ruth; Economidou, Daina; Theobald, David; Everitt, Barry J

    2012-10-01

    Whereas the majority of cocaine users quit as they experience the negative consequences of drug use, some lose control over their drug taking and compulsively seek drugs. We report that 20% of rats compulsively seek cocaine despite intermittent negative outcomes after escalating their cocaine self-administration. This compulsive subgroup showed marked reductions in forebrain serotonin utilization; increasing serotonin transmission reduced their compulsive cocaine seeking. Depleting forebrain serotonin induced compulsive cocaine seeking in rats with a limited cocaine taking history; this was reversed by systemic treatment with a 5-hydroxytryptamine (5-HT2C) receptor agonist and mimicked by systemic treatment with a 5-HT2C receptor antagonist in intact animals. These results indicate the causal involvement of reduced serotoninergic transmission in the emergence of compulsive drug seeking after a long cocaine-taking history. PMID:22763621

  15. Development of circumferential seal for helicopter transmissions: Results of bench and flight tests

    NASA Technical Reports Server (NTRS)

    Strom, T. N.; Ludwig, L. P.

    1975-01-01

    A modified circumferential segmented ring seal was designed for direct replacement of a helicopter transmission elastomeric lip seal operating on a shaft diameter of 13.91 centimeters (5.481 in.) at sliding velocities to 52.48 m/sec (10 330 ft/min). The modifications involved the garter spring tension, shaft roundness, seal housing flatness, and pumping grooves to inhibit leakage. Operation of the seals in bench tests under simulated helicopter transmission conditions revealed that the seal leakage rate was within acceptable limits and that the wear rate was negligible. The low leakage and wear rates were confirmed in flight tests of 600 and 175 hours (sliding speed, 48.11 m/sec (9470 ft/min)). An additional 200 hours of air worthiness qualification testing (aircraft tie down) demonstrated that the seal can operate at the advanced sliding conditions of 52.48 m/sec (10 330 ft/min).

  16. Development and commissioning of a transmission grating spectrometer on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Guymer, T. M.; Moore, A. S.; Morton, J.; Stevenson, R. M.

    2013-03-01

    The design and calibration of a soft X-ray transmission grating imaging spectrometer for the National Ignition Facility (NIF) [1] has been discussed elsewhere [2] and will be summarised here for ease. This work primarily discusses the supporting modelling and analysis techniques associated with the transmission grating spectrometer (TGS) and provides further analysis of the dedicated qualification shot on the NIF. Comparisons are made between: the CASSANDRA [3] opacity tables (used within the radiation-hydrodynamics code NYM [4]); the opacity derived from FLYCHK [5]; and the obtained spectrum using different analysis methods. Consideration is also given to the spectral resolution [6] of the diagnostic, the design aims of the diagnostic and limitations in the utilised codes.

  17. Economic Development from New Generation and Transmission in Wyoming and Colorado (Fact Sheet)

    SciTech Connect

    Not Available

    2013-03-01

    This report analyzes the potential economic impacts in Colorado and Wyoming of a 225 MW natural gas fired electricity generation facility and a 900 MW wind farm constructed in Wyoming as well as a 180 mile, 345 kV transmission line that runs from Wyoming to Colorado. This report and analysis is not a forecast, but rather an estimate of economic activity associated with a hypothetical scenario.

  18. Economic Development from New Generation and Transmission in Wyoming and Colorado

    SciTech Connect

    Keyser, D.; Lantz, E.

    2013-03-01

    This report analyzes the potential economic impacts in Colorado and Wyoming of a 225 MW natural gas fired electricity generation facility and a 900 MW wind farm constructed in Wyoming as well as a 180 mile, 345 kV transmission line that runs from Wyoming to Colorado. This report and analysis is not a forecast, but rather an estimate of economic activity associated with a hypothetical scenario.

  19. Surveillance of transfusion-transmissible infections comparison of systems in five developed countries.

    PubMed

    O'Brien, Sheila F; Zou, Shimian; Laperche, Syria; Brant, Lisa J; Seed, Clive R; Kleinman, Steven H

    2012-01-01

    Most industrialized countries maintain surveillance programs for monitoring transmissible infection in blood donations, revising approaches to methodology and risk assessment as new threats emerge. A comparison of programs in the United States, Canada, France, the UK, and Australia indicates that they have similar function, although the structure of blood programs vary as does the extent and nature of formal ties with public health. The emergence of HIV in the late 1970s and early 1980s was key in recognizing that surveillance systems specific to blood transfusion were essential. Hence, most industrialized countries monitor transfusion-transmissible infections in donors and evaluate the impact of new testing and of predonation screening strategies. Emerging infections since HIV have had different transmission pathways and challenged blood programs to draw upon resources for a rapid and effective response, with recognition that the original focus on sexual/drug-related risk of HIV and hepatitis was inadequate. The focus of surveillance programs on new and emerging pathogens fulfills a key role in risk assessment and policy formulation. The precise nature of such activities varies by country because of the structure of the blood programs and surveillance systems, the strategic focus of the blood programs, and the epidemiology of disease in each country. PMID:21944935

  20. Development of a hybrid wave based-transfer matrix model for sound transmission analysis.

    PubMed

    Dijckmans, A; Vermeir, G

    2013-04-01

    In this paper, a hybrid wave based-transfer matrix model is presented that allows for the investigation of the sound transmission through finite multilayered structures placed between two reverberant rooms. The multilayered structure may consist of an arbitrary configuration of fluid, elastic, or poro-elastic layers. The field variables (structural displacements and sound pressures) are expanded in terms of structural and acoustic wave functions. The boundary and continuity conditions in the rooms determine the participation factors in the pressure expansions. The displacement of the multilayered structure is determined by the mechanical impedance matrix, which gives a relation between the pressures and transverse displacements at both sides of the structure. The elements of this matrix are calculated with the transfer matrix method. First, the hybrid model is numerically validated. Next a comparison is made with sound transmission loss measurements of a hollow brick wall and a sandwich panel. Finally, numerical simulations show the influence of structural damping, room dimensions and plate dimensions on the sound transmission loss of multilayered structures. PMID:23556585

  1. Asymptomatic Leprosy Infection among Blood Donors May Predict Disease Development and Suggests a Potential Mode of Transmission

    PubMed Central

    Goulart, Isabela Maria Bernardes; Filho, Adilson Botelho; de Paiva, Paulo Henrique Ribeiro; Goulart, Luiz Ricardo

    2015-01-01

    Blood donor samples (1,007) were assessed for anti-phenolic glycolipid 1 (PGL-1) IgM antibodies and Mycobacterium leprae DNA presence, which had 3.8% and 0.3% positivity, respectively. After a 5-year follow-up period, six individuals with positive markers developed leprosy, raising the hypothesis that asymptomatic infection among blood donors may be an undisclosed mode of leprosy transmission via transfusion. PMID:26202111

  2. Development of a medical record and radiographic image transmission system using a high-speed communication network.

    PubMed

    Kim, N H; Yoo, S K; Kim, K M; Kang, Y T; Bae, S H; Kim, S R

    1998-01-01

    A medical record and radiographic image transmission system has been developed using a high-speed communication network. The databases are designed to store and transmit the data acquired from the scanner. To maximally utilize the communication bandwidth, the medical records and radiographic images are compressed using the G3 facsimile and JPEG coding standard method, respectively. TCP/IP, OOP and Windows-based system software enable a modular design, future expandability, open system interconnectivity, and diverse image manipulation functions. PMID:10384462

  3. Interactions Between Microbial Dynamics and Transport Processes in Variably Saturated Porous Media. 2. Model Development and Evaluation

    NASA Astrophysics Data System (ADS)

    Rockhold, M. L.; Yarwood, R. R.; Niemet, M. R.; Bottomley, P. J.; Selker, J. S.; Brockman, F. J.

    2001-12-01

    An experimental and numerical investigation was conducted to study interactions between microbial dynamics and transport processes in variably saturated porous media. A mathematical model is developed in this paper (Part 2) to describe the processes of water flow, solute transport, gas diffusion, and microbial dynamics, including bacterial cell growth, substrate consumption, and cell attachment to and detachment from solid-liquid and gas-liquid interfaces. A composite media model is used to account for the accumulation of an attached bacterial phase on the hydraulic properties of variably saturated porous media. Fluid-media scaling is used to account for possible biomass-induced changes in surface tension, contact angle, fluid viscosity, and density. The model is applied to simulate experiments conducted in sand-packed columns and in a light transmission chamber inoculated with a Pseudomonas fluorescens bacterium. The experimental results from the light transmission chamber are described in a companion paper by Yarwood et al. (Part 1).

  4. Developing a Dynamic Pharmacophore Model for HIV-1 Integrase

    SciTech Connect

    Carlson, Heather A.; Masukawa, Keven M.; Rubins, Kathleen; Bushman, Frederic; Jorgensen, William L.; Lins, Roberto; Briggs, James; Mccammon, Andy

    2000-05-11

    We present the first receptor-based pharmacophore model for HIV-1 integrase. The development of ''dynamic'' pharmacophore models is a new method that accounts for the inherent flexibility of the active site and aims to reduce the entropic penalties associated with binding a ligand. Furthermore, this new drug discovery method overcomes the limitation of an incomplete crystal structure of the target protein. A molecular dynamics (MD) simulation describes the flexibility of the uncomplexed protein. Many conformational models of the protein are saved from the MD simulations and used in a series of multi-unit search for interacting conformers (MUSIC) simulations. MUSIC is a multiple-copy minimization method, available in the BOSS program; it is used to determine binding regions for probe molecules containing functional groups that complement the active site. All protein conformations from the MD are overlaid, and conserved binding regions for the probe molecules are identified. Those conserved binding regions define the dynamic pharmacophore model. Here, the dynamic model is compared to known inhibitors of the integrase as well as a three-point, ligand-based pharmacophore model from the literature. Also, a ''static'' pharmacophore model was determined in the standard fashion, using a single crystal structure. Inhibitors thought to bind in the active site of HIV-1 integrase fit the dynamic model but not the static model. Finally, we have identified a set of compounds from the Available Chemicals Directory that fit the dynamic pharmacophore model, and experimental testing of the compounds has confirmed several new inhibitors.

  5. Developing a dynamic pharmacophore model for HIV-1 integrase.

    PubMed

    Carlson, H A; Masukawa, K M; Rubins, K; Bushman, F D; Jorgensen, W L; Lins, R D; Briggs, J M; McCammon, J A

    2000-06-01

    We present the first receptor-based pharmacophore model for HIV-1 integrase. The development of "dynamic" pharmacophore models is a new method that accounts for the inherent flexibility of the active site and aims to reduce the entropic penalties associated with binding a ligand. Furthermore, this new drug discovery method overcomes the limitation of an incomplete crystal structure of the target protein. A molecular dynamics (MD) simulation describes the flexibility of the uncomplexed protein. Many conformational models of the protein are saved from the MD simulations and used in a series of multi-unit search for interacting conformers (MUSIC) simulations. MUSIC is a multiple-copy minimization method, available in the BOSS program; it is used to determine binding regions for probe molecules containing functional groups that complement the active site. All protein conformations from the MD are overlaid, and conserved binding regions for the probe molecules are identified. Those conserved binding regions define the dynamic pharmacophore model. Here, the dynamic model is compared to known inhibitors of the integrase as well as a three-point, ligand-based pharmacophore model from the literature. Also, a "static" pharmacophore model was determined in the standard fashion, using a single crystal structure. Inhibitors thought to bind in the active site of HIV-1 integrase fit the dynamic model but not the static model. Finally, we have identified a set of compounds from the Available Chemicals Directory that fit the dynamic pharmacophore model, and experimental testing of the compounds has confirmed several new inhibitors. PMID:10841789

  6. Dynamic Assessment, Tutor Mediation and Academic Writing Development

    ERIC Educational Resources Information Center

    Shrestha, Prithvi; Coffin, Caroline

    2012-01-01

    Supporting undergraduate students with their academic literacies has recently been a major focus in higher education in the UK. This paper explores the value of tutor mediation in the context of academic writing development among undergraduate business studies students in open and distance learning, following the dynamic assessment (DA) approach…

  7. Development and Design of a Dynamic Multimedia Item Generation Mechanism

    ERIC Educational Resources Information Center

    Weng, Ting-Sheng

    2012-01-01

    This research applies multimedia technology to design a dynamic item generation method that can adaptively adjust the difficulty level of items according to the level of the testee. The method is based on interactive testing software developed by Flash Actionscript, and provides a testing solution for users by automatically distributing items of…

  8. Dynamic Development in Speaking versus Writing in Identical Twins

    ERIC Educational Resources Information Center

    Chan, HuiPing; Verspoor, Marjolijn; Vahtrick, Louisa

    2015-01-01

    Taking a dynamic usage-based perspective, this longitudinal case study compares the development of sentence complexity in speaking versus writing in two beginner Taiwanese learners of English (identical twins) in an extensive corpus consisting of 100 oral and 100 written texts of approximately 200 words produced by each twin over 8 months. Three…

  9. Dynamic Modeling for Development and Education: From Concepts to Numbers

    ERIC Educational Resources Information Center

    Van Geert, Paul

    2014-01-01

    The general aim of the article is to teach the reader how to transform conceptual models of change, development, and learning into mathematical expressions and how to use these equations to build dynamic models by means of the widely used spreadsheet program Excel. The explanation is supported by a number of Excel files, which the reader can…

  10. From Individual Differences to Dynamic Pathways of Development.

    ERIC Educational Resources Information Center

    Fischer, Kurt W.; Pare-Blagoev, Juliana

    2000-01-01

    Suggests ways to use dynamic systems analysis to illuminate the pluralistic and multidimensional model described by Larivee, Normandeau, and Parent (2000). Issues discussed include the characteristics of developmental transitions, such as hysteresis; nature of growth processes, such as hierarchical development or predator-prey interactions; and…

  11. A Dynamic Systems Theory Model of Visual Perception Development

    ERIC Educational Resources Information Center

    Coté, Carol A.

    2015-01-01

    This article presents a model for understanding the development of visual perception from a dynamic systems theory perspective. It contrasts to a hierarchical or reductionist model that is often found in the occupational therapy literature. In this proposed model vision and ocular motor abilities are not foundational to perception, they are seen…

  12. An automated dynamic load for power system development

    NASA Technical Reports Server (NTRS)

    Whitehead, Norma Dugal; Kapustka, Robert E.

    1988-01-01

    This paper describes a dynamic load which is computer-controlled and has an increased bandwidth of more than 10 times that commercially available at the time the development of the project began. The load is 3 kW with a bandwidth of 35 kHz. The hardware and software are described, and the control circuitry is shown.

  13. Introduction: Second Language Development as a Dynamic Process

    ERIC Educational Resources Information Center

    De Bot, Kees

    2008-01-01

    In this contribution, some of the basic characteristics of complex adaptive systems, collectively labeled Dynamic Systems Theory (DST), are discussed. Such systems are self-organizing, dependent on initial conditions, sometimes chaotic, and they show emergent properties. The focus in DST is on development over time. Language is seen as a dynamic…

  14. Development and Validation of the Primary Care Team Dynamics Survey

    PubMed Central

    Song, Hummy; Chien, Alyna T; Fisher, Josephine; Martin, Julia; Peters, Antoinette S; Hacker, Karen; Rosenthal, Meredith B; Singer, Sara J

    2015-01-01

    Objective To develop and validate a survey instrument designed to measure team dynamics in primary care. Data Sources/Study Setting We studied 1,080 physician and nonphysician health care professionals working at 18 primary care practices participating in a learning collaborative aimed at improving team-based care. Study Design We developed a conceptual model and administered a cross-sectional survey addressing team dynamics, and we assessed reliability and discriminant validity of survey factors and the overall survey's goodness-of-fit using structural equation modeling. Data Collection We administered the survey between September 2012 and March 2013. Principal Findings Overall response rate was 68 percent (732 respondents). Results support a seven-factor model of team dynamics, suggesting that conditions for team effectiveness, shared understanding, and three supportive processes are associated with acting and feeling like a team and, in turn, perceived team effectiveness. This model demonstrated adequate fit (goodness-of-fit index: 0.91), scale reliability (Cronbach's alphas: 0.71–0.91), and discriminant validity (average factor correlations: 0.49). Conclusions It is possible to measure primary care team dynamics reliably using a 29-item survey. This survey may be used in ambulatory settings to study teamwork and explore the effect of efforts to improve team-based care. Future studies should demonstrate the importance of team dynamics for markers of team effectiveness (e.g., work satisfaction, care quality, clinical outcomes). PMID:25423886

  15. Development of a solid propellant viscoelastic dynamic model

    NASA Technical Reports Server (NTRS)

    Hufferd, W. L.; Fitzgerald, J. E.

    1976-01-01

    The results of a one year study to develop a dynamic response model for the Space Shuttle Solid Rocket Motor (SRM) propellant are presented. An extensive literature survey was conducted, from which it was concluded that the only significant variables affecting the dynamic response of the SRM propellant are temperature and frequency. Based on this study, and experimental data on propellants related to the SRM propellant, a dynamic constitutive model was developed in the form of a simple power law with temperature incorporated in the form of a modified power law. A computer program was generated which performs a least-squares curve-fit of laboratory data to determine the model parameters and it calculates dynamic moduli at any desired temperature and frequency. Additional studies investigated dynamic scaling laws and the extent of coupling between the SRM propellant and motor cases. It was found, in agreement with other investigations, that the propellant provides all of the mass and damping characteristics whereas the case provides all of the stiffness.

  16. Development and evaluation of a dynamic web-based application.

    PubMed

    Hsieh, Yichuan; Brennan, Patricia Flatley

    2007-01-01

    Traditional consumer health informatics (CHI) applications that were developed for lay public on the Web were commonly written in a Hypertext Markup Language (HTML). As genetics knowledge rapidly advances and requires updating information in a timely fashion, a different content structure is therefore needed to facilitate information delivery. This poster will present the process of developing a dynamic database-driven Web CHI application. PMID:18694081

  17. Development of 1200-kV compressed-gas-insulated transmission and substation equipment in the United States

    SciTech Connect

    Walldorf, S.P.; Gnadt, P.A.

    1986-01-01

    Major research and development (R and D) programs for the development of sulfur hexafluoride (SF/sub 6/) compressed-gas-insulated (CGI) equipment for ultrahighvoltage (uhv) application at 100-1200 kV have been under way independently in both the United States and Japan. The CGI transmission and substation equipment under study and development in these countries has included the surge arrester, circuit breaker, CGI transmission bus, disconnect and ground switches, and an air-SF/sub 6/ termination. The US CGI program has also included development of a power transformer, shunt reactor, voltage- and current-sensing instrumentation, and a line trap, all for 1200-kV application. This paper presents the overall status of development of CGI substation equipment for uhv application in the United States. It describes the major CGI components developed, highlights their key design aspects, indicates the present status of development and testing, and addresses the work remaining to establish final design consepts. The paper also includes 23 references, a number of which have not been widely distributed or included in any of the recently published bibliographies of uhv substation equipment.

  18. Accelerated molecular dynamics methods: introduction and recent developments

    SciTech Connect

    Uberuaga, Blas Pedro; Voter, Arthur F; Perez, Danny; Shim, Y; Amar, J G

    2009-01-01

    A long-standing limitation in the use of molecular dynamics (MD) simulation is that it can only be applied directly to processes that take place on very short timescales: nanoseconds if empirical potentials are employed, or picoseconds if we rely on electronic structure methods. Many processes of interest in chemistry, biochemistry, and materials science require study over microseconds and beyond, due either to the natural timescale for the evolution or to the duration of the experiment of interest. Ignoring the case of liquids xxx, the dynamics on these time scales is typically characterized by infrequent-event transitions, from state to state, usually involving an energy barrier. There is a long and venerable tradition in chemistry of using transition state theory (TST) [10, 19, 23] to directly compute rate constants for these kinds of activated processes. If needed dynamical corrections to the TST rate, and even quantum corrections, can be computed to achieve an accuracy suitable for the problem at hand. These rate constants then allow them to understand the system behavior on longer time scales than we can directly reach with MD. For complex systems with many reaction paths, the TST rates can be fed into a stochastic simulation procedure such as kinetic Monte Carlo xxx, and a direct simulation of the advance of the system through its possible states can be obtained in a probabilistically exact way. A problem that has become more evident in recent years, however, is that for many systems of interest there is a complexity that makes it difficult, if not impossible, to determine all the relevant reaction paths to which TST should be applied. This is a serious issue, as omitted transition pathways can have uncontrollable consequences on the simulated long-time kinetics. Over the last decade or so, we have been developing a new class of methods for treating the long-time dynamics in these complex, infrequent-event systems. Rather than trying to guess in advance what

  19. Mitochondrial biogenesis and dynamics in the developing and diseased heart

    PubMed Central

    Dorn, Gerald W.; Vega, Rick B.; Kelly, Daniel P.

    2015-01-01

    The mitochondrion is a complex organelle that serves essential roles in energy transduction, ATP production, and a myriad of cellular signaling events. A finely tuned regulatory network orchestrates the biogenesis, maintenance, and turnover of mitochondria. The high-capacity mitochondrial system in the heart is regulated in a dynamic way to generate and consume enormous amounts of ATP in order to support the constant pumping function in the context of changing energy demands. This review describes the regulatory circuitry and downstream events involved in mitochondrial biogenesis and its coordination with mitochondrial dynamics in developing and diseased hearts. PMID:26443844

  20. New developments and test of high power transmission components for ECRH on ASDEX-Upgrade and W7-AS

    SciTech Connect

    Empacher, L.; Foerster, W.; Gantenbein, G.; Kasparek, W.; Kumric, H.

    1995-12-31

    The installation of new 140 GHz systems for electron cyclotron heating on the tokamak ASDEX-Upgrade and the stellarator W7-AS with a power of 2 MW each and 3 s pulse length is underway. These systems use gyrotrons, developed by the Institute of Applied Physics, Nizhny Novgorod, and built by Toriy in Russia, as high power mm-wave sources. The gyrotrons can be operated for 3 s with 0.5 MW and for 1 s with 0.7 MW EHF output. The transmission of the millimetre wave power is realized by a combination of beam waveguides and corrugated HE{sub 11} waveguides. Components for transmission and high power diagnostics as well as first results are described together with the system.