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Sample records for improve symbiotic system

  1. Symbiotic systems: observations and theory

    NASA Astrophysics Data System (ADS)

    Luna, Gerardo

    2016-07-01

    Although there is wide concensus about the binary nature of symbiotic stars, the nature of their central engine, the structure of the accretion flow and the accretion rate are poorly known. Modern observatories are now providing, for the first time, direct information about the central source of power and how it is fueled. The detection of hard (E > 20 keV) X-ray emission from a handful of symbiotics indicates that some symbiotics accrete at a low enough rate for a ˜10^{8} K accretion-disk boundary layer to remain optically thin and generate hard X-rays. Such high temperature is possible if the white dwarf is massive; symbiotics could thus be SNIa progenitors, the pilars of the current cosmological paradigm.

  2. Physiological limitations and the genetic improvement of symbiotic nitrogen fixation

    SciTech Connect

    Gara, F.O.; Manian, S. ); Drevon, J.J. )

    1988-01-01

    The rhizobium legume symbiosis continues to be of strategic importance particularly in the context of food production. As the world population grows, it is necessary that new developments take place in crop improvement. The development and application of new technologies in biological sciences over past years has made the entire area of plant-microbial interaction an exciting and challenging research area to be involved in. In view of the importance of symbiotic nitrogen fixation, it is not surprising that it still represents one of the priority areas for commercial development in agricultural biotechnology. Since this symbiosis involves an association between procaryotic and eucaryhotic partners, it requires of necessity a coordinated and interdisciplinary approach. This book focuses on physiological limitations affecting symbiotic nitrogen fixation and the potential for overcoming such limitations by using genetic technologies.

  3. Dynamic task allocation for a man-machine symbiotic system

    NASA Technical Reports Server (NTRS)

    Parker, L. E.; Pin, F. G.

    1987-01-01

    This report presents a methodological approach to the dynamic allocation of tasks in a man-machine symbiotic system in the context of dexterous manipulation and teleoperation. This report addresses a symbiotic system containing two symbiotic partners which work toward controlling a single manipulator arm for the execution of a series of sequential manipulation tasks. It is proposed that an automated task allocator use knowledge about the constraints/criteria of the problem, the available resources, the tasks to be performed, and the environment to dynamically allocate task recommendations for the man and the machine. The presentation of the methodology includes discussions concerning the interaction of the knowledge areas, the flow of control, the necessary communication links, and the replanning of the task allocation. Examples of task allocation are presented to illustrate the results of this methodolgy.

  4. The Symbiotic System SS73 17 seen with Suzaku

    NASA Technical Reports Server (NTRS)

    Smith, Randall K.; Mushotzky, Richard; Kallman, Tim; Tueller, Jack; Mukai, Koji; Markwardt, Craig

    2007-01-01

    We observed with Suzaku the symbiotic star SS73 17, motivated by the discovery by the INTEGRAL satellite and the Swift BAT survey that it emits hard X-rays. Our observations showed a highly-absorbed X-ray spectrum with NH > loz3 emp2, equivalent to Av > 26, although the source has B magnitude 11.3 and is also bright in UV. The source also shows strong, narrow iron lines including fluorescent Fe K as well as Fe xxv and Fe XXVI. The X-ray spectrum can be fit with a thermal model including an absorption component that partially covers the source. Most of the equivalent width of the iron fluorescent line in this model can be explained as a combination of reprocessing in a dense absorber plus reflection off a white dwarf surface, but it is likely that the continuum is partially seen in reflection as well. Unlike other symbiotic systems that show hard X-ray emission (CH Cyg, RT Cru, T CrB, GX1+4), SS73 17 is not known to have shown nova-like optical variability, X-ray flashes, or pulsations, and has always shown faint soft X-ray emission. As a result, although it is likely a white dwarf, the nature of the compact object in SS73 17 is still uncertain. SS73 17 is probably an extreme example of the recently discovered and relatively small class of hard X-ray emitting symbiotic systems.

  5. Role of time in symbiotic systems

    SciTech Connect

    Agrawala, A.K.

    1996-12-31

    All systems have a dynamics which reflects the changes in the system in time and, therefore, have to maintain a notion of time, either explicitly or implicitly. Traditionally, the notion of time in constructed systems has been implicitly specified at design time through rigid structures such as sampled data systems which operate with a fixed time tick, feedback systems which are designed reflecting a fixed time scale for the dynamics of the system as well as the controller responses, etc. In biological systems, the sense of time is a key element but it is not rigidly structured, even though all such systems have a clear notion of time. We define the notion of time in systems in terms of temporal locality, time scale and time horizon. Temporal locality gives the notion of the accuracy with which the system knows about the current time. Time scale reflects the scale indicating the smallest and the largest granularity considered. It also reflects the reaction time. The time horizon indicates the time beyond which the system considers to be distant future and may not take it into account in its actions. Note that the temporal locality, time scale and the time horizon may be different for different types of actions of a system, thereby permitting the system to use multiple notions of time concurrently. In multi agent systems each subsystem may have its own notion of time but when intentions take place a coordination is necessary. Such coordination requires that the notions of time for different agents of the system be consistent. Clearly, the consistency requirement in this case does not mean exactly identical but implies that different agents can coordinate their actions which must take place in time. When the actions only require a determinate ordering the required coordination is much less severe than the case requiring actions to take place at the same time.

  6. Infrared Spectroscopy of Symbiotic Stars. I. Orbits for Well-Known S-Type Systems

    NASA Astrophysics Data System (ADS)

    Fekel, Francis C.; Joyce, Richard R.; Hinkle, Kenneth H.; Skrutskie, Michael F.

    2000-03-01

    First results are reported for a program of monitoring symbiotic-star velocities in the 1.6 μm region with infrared-array technology. Infrared radial velocities have been used to determine single-lined spectroscopic orbits for six well-known symbiotic stars, EG And, T CrB, CI Cyg, BX Mon, RS Oph, and AG Peg. The new orbits are in general agreement with previous orbits derived from optical velocities. From the combined optical and infrared velocities improved orbital elements for the six systems have been determined. Each of the orbital periods has been determined solely from the radial-velocity data. With the addition of our new velocities, the orbital period of BX Mon has been revised to 1259 days, a 10% decrease from the previously reported result.

  7. Multi Groups Cooperation based Symbiotic Evolution for TSK-type Neuro-Fuzzy Systems Design.

    PubMed

    Cheng, Yi-Chang; Hsu, Yung-Chi; Lin, Sheng-Fuu

    2010-07-01

    In this paper, a TSK-type neuro-fuzzy system with multi groups cooperation based symbiotic evolution method (TNFS-MGCSE) is proposed. The TNFS-MGCSE is developed from symbiotic evolution. The symbiotic evolution is different from traditional GAs (genetic algorithms) that each chromosome in symbiotic evolution represents a rule of fuzzy model. The MGCSE is different from the traditional symbiotic evolution; with a population in MGCSE is divided to several groups. Each group formed by a set of chromosomes represents a fuzzy rule and cooperate with other groups to generate the better chromosomes by using the proposed cooperation based crossover strategy (CCS). In this paper, the proposed TNFS-MGCSE is used to evaluate by numerical examples (Mackey-Glass chaotic time series and sunspot number forecasting). The performance of the TNFS-MGCSE achieves excellently with other existing models in the simulations. PMID:21709856

  8. Multi Groups Cooperation based Symbiotic Evolution for TSK-type Neuro-Fuzzy Systems Design

    PubMed Central

    Cheng, Yi-Chang; Hsu, Yung-Chi

    2010-01-01

    In this paper, a TSK-type neuro-fuzzy system with multi groups cooperation based symbiotic evolution method (TNFS-MGCSE) is proposed. The TNFS-MGCSE is developed from symbiotic evolution. The symbiotic evolution is different from traditional GAs (genetic algorithms) that each chromosome in symbiotic evolution represents a rule of fuzzy model. The MGCSE is different from the traditional symbiotic evolution; with a population in MGCSE is divided to several groups. Each group formed by a set of chromosomes represents a fuzzy rule and cooperate with other groups to generate the better chromosomes by using the proposed cooperation based crossover strategy (CCS). In this paper, the proposed TNFS-MGCSE is used to evaluate by numerical examples (Mackey-Glass chaotic time series and sunspot number forecasting). The performance of the TNFS-MGCSE achieves excellently with other existing models in the simulations. PMID:21709856

  9. [Full-scale experiments of municipal sewage treated by symbiotic system consisting of tubifex and microbes].

    PubMed

    Lou, Ju-qing; Guo, Mao-xin; Sun, Pei-de; Wu, Ge; Song, Ying-qi

    2009-12-01

    A symbiotic system consisting of tubifex and microbe was formed when tubifex was incubated in the biological contact oxidation process,the tubifex attached to the outer layer of the carriers. When the density of tubifex was about 31.3 g/L, a recycling food chain between corpse of tubifex and excrement and wastewater and microbe and sludge was formed and it could reach balance. The large scale control experimental system for treating 20,000 m3 x d(-1) municipal sewage was carried out for a long time. The result showed that tubifex could improve water quality in the effluent. When the concentration in the influent of COD,NH4+ -N,TP and SS were 130-459, 14.21-27.46, 1.60-6.93, 60-466 mg x L(-1), respectively,the removal rates of COD and SS can be improved by 8.7% and 13.6%. However, tubifex can also increase the concentration of NH4+ -N in the system,but a proper operation can make the effluent concentration of NH4+ -N below 5 mg x L(-1) stably. The symbiotic system consisting of tubifex and microbe has very good phosphorus removal efficiency. The reactor has a high toleration to loading shock and it could keep the effluent quality stable. PMID:20187394

  10. Evolution of the symbiotic binary system AG Dranconis

    NASA Technical Reports Server (NTRS)

    Mikolajewska, Joanna; Kenyon, Scott J; Mikolajewski, Maciej; Garcia, Michael R.; Polidan, Ronald S.

    1995-01-01

    We present an analysis of new and archival photometric and spectroscopic observations of the symbiotic star AG Draconis. This binary has undergone several 1 - 3 mag optical and ultraviolet eruptions during the past 15 years. Our combination of optical and ultraviolet spectroscopic data allow a more complete analysis of this system than in previous papers. AG Dra is composed of a K-type bright giant M(sub g) approximately 1.5 solar mass) and a hot, compact star M(sub h approximatelly 0.4 - 0.6 solar mass) embedded in a dense, low metallicity nebula. The hot component undergoes occasional thermonuclear runaways that produce 2 - 3 mag optical/ultraviolet eruptions. During these eruptions, the hot component develops a low velocity wind that quenches x-ray emission from the underlying hot white dwarf. The photoionized nebula changes its volume by a factor of 5 throughout an eruptin cycle. The K bright giant occults low ionization emission lines during superior conjunctions at all outburst phases but does not occult high ionization lines in outburst (and perhaps quiescence). This geometry and the component masses suggest a system inclination of i approximately 30 deg - 45 deg.

  11. THE THERAPEUTIC USE OF SYMBIOTICS

    PubMed Central

    FLESCH, Aline Gamarra Taborda; POZIOMYCK, Aline Kirjner; DAMIN, Daniel De Carvalho

    2014-01-01

    Introduction Functional foods are health promoters and their use is associated with reduced risk of chronic degenerative and non-transmissible diseases. Examples are symbiotic. The association of one (or more) probiotic with a one (or more) prebiotic is called symbiotic, being the prebiotics complementary and probiotics synergistic, thus presenting a multiplicative factor on their individual actions. Objective To assess the evidences on the benefits of the use of symbiotics in the treatment of clinical and surgical situations. Methods The headings symbiotic, probiotic and prebiotic were searched in Pubmed/Medline in the last 15 years, and were selected 25 articles, used for database. Results The use of symbiotic may promote an increase in the number of bifidobacteria, glycemic control, reduction of blood cholesterol, balancing the intestinal flora which aids in reducing constipation and/or diarrhea, improves intestinal permeability and stimulation of the immune system. Clinical indications for these products has been expanded, in order to maximize the individual's physiological functions to provide greater. So, with the high interest in the clinical and nutritional control of disease, many studies have been conducted demonstrating the effectiveness of using symbiotic in improving and/or preventing various and/or symptoms of gastrointestinal diseases. Conclusion Symbiotic behave differently and positively in various pathological situations. PMID:25184774

  12. Symbiotic Expressions

    NASA Astrophysics Data System (ADS)

    Bernecky, Robert; Herhut, Stephan; Scholz, Sven-Bodo

    We introduce symbiotic expressions, a method for algebraic simplification within a compiler, in lieu of an SMT solver, such as Yices or the Omega Calculator. Symbiotic expressions are compiler-generated expressions, temporarily injected into a program's abstract syntax tree (AST). The compiler's normal optimizations interpret and simplify those expressions, making their results available for the compiler to use as a basis for decisions about further optimization of the source program. The expressions are symbiotic, in the sense that both parties benefit: an optimization benefits, by using the compiler itself to simplify expressions that have been attached, lamprey-like, to the AST by the optimization; the program being compiled benefits, from improved run-time in both serial and parallel environments.

  13. Job planning and execution monitoring for a human-robot symbiotic system

    SciTech Connect

    Parker, L.E.

    1989-11-01

    The human-robot symbiosis concept has the fundamental objective of bridging the gap between fully human-controlled and fully autonomous systems to achieve true human-robot cooperative control and intelligence. Such a system would allow improved speed, accuracy, and efficiency of task execution, while retaining the human in the loop for innovative reasoning and decision-making. Earlier research has resulted in the development of a robotic system architecture facilitating the symbiotic integration of teleoperative and automated modes of task execution. This architecture reflects a unique blend of many disciplines of artificial intelligence into a working system, including job or mission planning, dynamic task allocation, human-robot communication, automated monitoring, and machine learning. This report focuses on two elements of this architecture: the Job Planner and the Automated Monitor. 17 refs., 7 figs.

  14. Symbiotic stars

    NASA Technical Reports Server (NTRS)

    Kafatos, M.; Michalitsianos, A. G.

    1984-01-01

    The physical characteristics of symbiotic star systems are discussed, based on a review of recent observational data. A model of a symbiotic star system is presented which illustrates how a cool red-giant star is embedded in a nebula whose atoms are ionized by the energetic radiation from its hot compact companion. UV outbursts from symbiotic systems are explained by two principal models: an accretion-disk-outburst model which describes how material expelled from the tenuous envelope of the red giant forms an inwardly-spiralling disk around the hot companion, and a thermonuclear-outburst model in which the companion is specifically a white dwarf which superheats the material expelled from the red giant to the point where thermonuclear reactions occur and radiation is emitted. It is suspected that the evolutionary course of binary systems is predetermined by the initial mass and angular momentum of the gas cloud within which binary stars are born. Since red giants and Mira variables are thought to be stars with a mass of one or two solar mass, it is believed that the original cloud from which a symbiotic system is formed can consist of no more than a few solar masses of gas.

  15. Colliding Winds in Symbiotic Binary Systems. II. Colliding Winds Geometries and Orbital Motion in the Symbiotic Nova AG Pegasi

    NASA Astrophysics Data System (ADS)

    Kenny, H. T.; Taylor, A. R.

    2007-06-01

    AG Pegasi has been observed at high angular resolution and sensitivity at the Very Large Array (VLA) at 5 GHz in four epochs between 1984 and 1991. Analysis of the radio visibilities indicate that a mass of 4.0+/-0.5×10-5 Msolar is concentrated in the inner nebula and is moving outward at a velocity of 53+/-4 km s-1 (D=600 pc assumed). In order to explain the observed morphology of the inner nebula, a new colliding winds model is derived, which includes the effects of orbital motion (CWo model). Orbital effects cannot be ignored in AG Pegasi since the orbital timescale (2.25 yr; Meinunger 1981) is short compared to the likely timescale of wind collision (symbiotic nova eruption beginning ~1850 Merrill 1959). When these effects are considered, the interaction front between binary stellar winds is wrapped into spiral walls whose density decreases outward with 1/r2. Distinctive geometries are found to arise depending on which wind dominates the interaction, the late-type wind from the symbiotic ``cool component,'' or the high-velocity wind from the ``hot component.'' Application of the CWo model to AG Peg suggests that the observed transient lobe enhancements of the inner nebula arise due to changes in the mass-loss rate from the hot component. Hot component mass-loss rates ranging between 2.1 and 6.0×10-8 Msolar yr-1 are derived. The model is also successful in reproducing the radio spectrum of the central unresolved object of the system. A position angle of -15deg+/-10deg is inferred for the orbital pole as projected on the plane of the sky.

  16. On the effect of ionization on the circumbinary material in symbiotic systems

    NASA Astrophysics Data System (ADS)

    Shagatova, N.

    2015-12-01

    A double nature of the circumbinary matter in symbiotic systems, i. e. the presence of H0 and H+ regions, offers an opportunity to investigate both the properties of the wind from the donor star and the effect of radiation from the ionizing companion onto the surrounding material. In this contribution we explain the importance of the effect of ionization for a proper treating of the inversion problem for the wind velocity profile. The method allows us to obtain the models for total and neutral hydrogen column densities and corresponding wind velocity profiles. We describe in detail the process of modelling for the spherically symmetric wind and compare it with simpler approaches. The first application of our improved approach revealed that the effect of ionization on the column density shapes is not negligible for a wide range of orbital phases, in contrast to the assumptions in previous papers. Thus, it implies a higher concentration of the wind matter than it was supposed before.

  17. Chemical abundance analysis of symbiotic giants - III. Metallicity and CNO abundance patterns in 24 southern systems

    NASA Astrophysics Data System (ADS)

    Gałan, Cezary; Mikołajewska, Joanna; Hinkle, Kenneth H.; Joyce, Richard R.

    2016-01-01

    The elemental abundances of symbiotic giants are essential to address the role of chemical composition in the evolution of symbiotic binaries, to map their parent population, and to trace their mass transfer history. However, the number of symbiotic giants with fairly well determined photospheric composition is still insufficient for statistical analyses. This is the third in a series of papers on the chemical composition of symbiotic giants determined from high-resolution (R ˜ 50 000), near-infrared spectra. Here we present results for 24 S-type systems. Spectrum synthesis methods employing standard local thermal equilibrium analysis and atmosphere models were used to obtain photospheric abundances of CNO and elements around the iron peak (Fe, Ti, Ni, and Sc). Our analysis reveals metallicities distributed in a wide range from slightly supersolar ([Fe/H] ˜ +0.35 dex) to significantly subsolar ([Fe/H] ˜ -0.8 dex) but principally with near-solar and slightly subsolar metallicity ([Fe/H] ˜ -0.4 to -0.3 dex). The enrichment in 14N isotope, found in all these objects, indicates that the giants have experienced the first dredge-up. This was confirmed in a number of objects by the low 12C/13C ratio (5-23). We found that the relative abundance of [Ti/Fe] is generally large in red symbiotic systems.

  18. Symbiotic Stars

    NASA Astrophysics Data System (ADS)

    Munari, U.

    2012-06-01

    Symbiotic stars are interacting binary systems composed of a white dwarf (WD) accreting at high rate from a cool giant companion, which frequently fills its Roche lobe. The WD usually is extremely hot and luminous, and able to ionize a sizeable fraction of the cool giant wind, because it is believed the WD undergoes stable hydrogen nuclear burning on its surface of the material accreted from the companion. This leads to consider symbiotic stars as good candidates for the yet-to-be-identified progenitors of type Ia supernovae. Symbiotic stars display the simultaneous presence of many different types of variability, induced by the cool giant, the accreting WD, the circumstellar dust and ionized gas, with time scales ranging from seconds to decades. The long orbital periods (typically a couple of years) and complex outburst patterns, lasting from a few years to a century, make observations from professionals almost impossible to carry out, and open great opportunities to amateur astronomers to contribute fundamental data to science.

  19. Population genetic data of a model symbiotic cnidarian system reveal remarkable symbiotic specificity and vectored introductions across ocean basins.

    PubMed

    Thornhill, Daniel J; Xiang, Yu; Pettay, D Tye; Zhong, Min; Santos, Scott R

    2013-09-01

    The Aiptasia-Symbiodinium symbiosis is a promising model for experimental studies of cnidarian-dinoflagellate associations, yet relatively little is known regarding the genetic diversity of either symbiotic partner. To address this, we collected Aiptasia from 16 localities throughout the world and examined the genetic diversity of both anemones and their endosymbionts. Based on newly developed SCAR markers, Aiptasia consisted of two genetically distinct populations: one Aiptasia lineage from Florida and a second network of Aiptasia genotypes found at other localities. These populations did not conform to the distributions of described Aiptasia species, suggesting that taxonomic re-evaluation is needed in the light of molecular genetics. Associations with Symbiodinium further demonstrated the distinctions among Aiptasia populations. According to 18S RFLP, ITS2-DGGE and microsatellite flanker region sequencing, Florida anemones engaged in diverse symbioses predominantly with members of Symbiodinium Clades A and B, but also C, whereas anemones from elsewhere harboured only S. minutum within Clade B. Symbiodinium minutum apparently does not form a stable symbiosis with other hosts, which implies a highly specific symbiosis. Fine-scale differences among S. minutum populations were quantified using six microsatellite loci. Populations of S. minutum had low genotypic diversity and high clonality (R = 0.14). Furthermore, minimal population structure was observed among regions and ocean basins, due to allele and genotype sharing. The lack of genetic structure and low genotypic diversity suggest recent vectoring of Aiptasia and S. minutum across localities. This first ever molecular-genetic study of a globally distributed cnidarian and its Symbiodinium assemblages reveals host-symbiont specificity and widely distributed populations in an important model system. PMID:23980764

  20. A PRECESSING JET IN THE CH Cyg SYMBIOTIC SYSTEM

    SciTech Connect

    Karovska, Margarita; Gaetz, Terrance J.; Raymond, John C.; Lee, Nicholas P.; Carilli, Christopher L.; Hack, Warren

    2010-02-20

    Jets have been detected in only a few symbiotic binaries to date, and CH Cyg is one of them. In 2001, a non-relativistic jet was detected in CH Cyg for the first time in X-rays. We carried out coordinated Chandra, Hubble Space Telescope (HST), and VLA observations in 2008 to study the propagation of this jet and its interaction with the circumbinary medium. We detected the jet with Chandra and HST and determined that the apex has expanded to the south from {approx}300 AU to {approx}1400 AU, with the shock front propagating with velocity <100 km s{sup -1}. The shock front has significantly slowed down since 2001. Unexpectedly, we also discovered a powerful jet in the NE-SW direction, in the X-ray, optical and radio. This jet has a multi-component structure, including an inner jet and a counterjet at {approx}170 AU, and a SW component ending in several clumps extending out to {approx}750 AU. The structure of the jet and the curvature of the outer portion of the SW jet suggest an episodically powered precessing jet or a continuous precessing jet with occasional mass ejections or pulses. We carried out detailed spatial mapping of the X-ray emission and correlation with the optical and radio emission. X-ray spectra were extracted from the central source, inner NE counterjet, and the brightest clump at a distance of {approx}500 AU from the central source. We discuss the initial results of our analyses, including the multi-component spectral fitting of the jet components and of the central source.

  1. A study of the mass loss rates of symbiotic star systems

    NASA Astrophysics Data System (ADS)

    Korreck, K. E.; Kellogg, E.; Sokoloski, J. L.

    2007-08-01

    The amount of mass loss in symbiotic systems is investigated, specifically mass loss via the formation of jets in R Aquarii (R Aqr). The jets in R Aqr have been observed in the X-ray by Chandra over a four year time period. The jet changes on times scales of a year and new outflows have been observed. Understanding the amount of mass and the frequency of ejection further constrain the ability of the white dwarf in the system to accrete enough mass to become a Type 1a supernova progenitor. The details of multi-wavelength studies, such as speed, density and spatial extent of the jets will be discussed in order to understand the mass balance in the binary system. We examine other symbiotic systems to determine trends in mass loss in this class of objects.

  2. A Study of the Mass Loss Rates of Symbiotic Star Systems

    NASA Technical Reports Server (NTRS)

    Korreck, K. E.; Kellogg, E.; Sokoloski, J. L.

    2007-01-01

    The amount of mass loss in symbiotic systems is investigated, specifically mass loss via the formation of jets in R Aquarii (R Aqr). The jets in R Aqr have been observed in the X-ray by Chandra over a four year time period. The jet changes on times scales of a year and new outflows have been observed. Understanding the amount of mass and the frequency of ejection further constrain the ability of the white dwarf in the system to accrete enough mass to become a Type la supernova progenitor. The details of multi-wavelength studies, such as speed, density and spatial extent of the jets will be discussed in order to understand the mass balance in the binary system. We examine other symbiotic systems to determine trends in mass loss in this class of objects.

  3. Social network analysis and network connectedness analysis for industrial symbiotic systems: model development and case study

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Zheng, Hongmei; Chen, Bin; Yang, Naijin

    2013-06-01

    An important and practical pattern of industrial symbiosis is rapidly developing: eco-industrial parks. In this study, we used social network analysis to study the network connectedness (i.e., the proportion of the theoretical number of connections that had been achieved) and related attributes of these hybrid ecological and industrial symbiotic systems. This approach provided insights into details of the network's interior and analyzed the overall degree of connectedness and the relationships among the nodes within the network. We then characterized the structural attributes of the network and subnetwork nodes at two levels (core and periphery), thereby providing insights into the operational problems within each eco-industrial park. We chose ten typical ecoindustrial parks in China and around the world and compared the degree of network connectedness of these systems that resulted from exchanges of products, byproducts, and wastes. By analyzing the density and nodal degree, we determined the relative power and status of the nodes in these networks, as well as other structural attributes such as the core-periphery structure and the degree of sub-network connectedness. The results reveal the operational problems created by the structure of the industrial networks and provide a basis for improving the degree of completeness, thereby increasing their potential for sustainable development and enriching the methods available for the study of industrial symbiosis.

  4. IGR J17463-2854, a possible symbiotic binary system in the galactic center region

    NASA Astrophysics Data System (ADS)

    Karasev, D. I.; Tsygankov, S. S.; Lutovinov, A. A.

    2015-08-01

    This paper is devoted to determining the nature of the hard X-ray source IGR J17463-2854 located toward the Galactic bulge. Using data from the INTEGRAL and Chandra X-ray observatories, we show that five point X-ray sources with approximately identical fluxes in the 2-10 keV energy band are detected in the error circle of the object under study. In addition, significant absorption at low energies has been detected in the spectra of all these sources. Based on data from the VVV (VISTA/ESO) infrared Galactic Bulge Survey, we have unambiguously identified three of the five sources, determined the J, H, and K magnitudes of the corresponding stars, and obtained upper limits on the fluxes for the remaining two sources. Analysis of the color-magnitude diagrams has shown that one of these objects most likely belongs to a class of rarely encountered objects, symbiotic binary systems (several tens are known with certainty), i.e., low-mass binary systems consisting of a white dwarf and a red giant. It is important to note that all our results were obtained using improved absorption values and an extinction law differing in this direction from the standard one.

  5. Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems

    SciTech Connect

    D. E. Shropshire

    2009-01-01

    The Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems, prepared to support the U.S. Advanced Fuel Cycle Initiative (AFCI) systems analysis, provides a technology-oriented baseline system cost comparison between the open fuel cycle and closed fuel cycle systems. The intent is to understand their overall cost trends, cost sensitivities, and trade-offs. This analysis also improves the AFCI Program’s understanding of the cost drivers that will determine nuclear power’s cost competitiveness vis-a-vis other baseload generation systems. The common reactor-related costs consist of capital, operating, and decontamination and decommissioning costs. Fuel cycle costs include front-end (pre-irradiation) and back-end (post-iradiation) costs, as well as costs specifically associated with fuel recycling. This analysis reveals that there are large cost uncertainties associated with all the fuel cycle strategies, and that overall systems (reactor plus fuel cycle) using a closed fuel cycle are about 10% more expensive in terms of electricity generation cost than open cycle systems. The study concludes that further U.S. and joint international-based design studies are needed to reduce the cost uncertainties with respect to fast reactor, fuel separation and fabrication, and waste disposition. The results of this work can help provide insight to the cost-related factors and conditions needed to keep nuclear energy (including closed fuel cycles) economically competitive in the U.S. and worldwide. These results may be updated over time based on new cost information, revised assumptions, and feedback received from additional reviews.

  6. Improved Phytophthora resistance in commercial chickpea (Cicer arietinum) varieties negatively impacts symbiotic gene signalling and symbiotic potential in some varieties.

    PubMed

    Plett, Jonathan M; Plett, Krista L; Bithell, Sean L; Mitchell, Chris; Moore, Kevin; Powell, Jeff R; Anderson, Ian C

    2016-08-01

    Breeding disease-resistant varieties is one of the most effective and economical means to combat soilborne diseases in pulse crops. Commonalities between pathogenic and mutualistic microbe colonization strategies, however, raises the concern that reduced susceptibility to pathogens may simultaneously reduce colonization by beneficial microbes. We investigate here the degree of overlap in the transcriptional response of the Phytophthora medicaginis susceptible chickpea variety 'Sonali' to the early colonization stages of either Phytophthora, rhizobial bacteria or arbuscular mycorrhizal fungi. From a total of 6476 genes differentially expressed in Sonali roots during colonization by any of the microbes tested, 10.2% were regulated in a similar manner regardless of whether it was the pathogenic oomycete or a mutualistic microbe colonizing the roots. Of these genes, 49.7% were oppositely regulated under the same conditions in the moderately Phytophthora resistant chickpea variety 'PBA HatTrick'. Chickpea varieties with improved resistance to Phytophthora also displayed lower colonization by rhizobial bacteria and mycorrhizal fungi leading to an increased reliance on N and P from soil. Together, our results suggest that marker-based breeding in crops such as chickpea should be further investigated such that plant disease resistance can be tailored to a specific pathogen without affecting mutualistic plant:microbe interactions. PMID:27103212

  7. Models of symbiotic stars

    NASA Technical Reports Server (NTRS)

    Friedjung, Michael

    1993-01-01

    One of the most important features of symbiotic stars is the coexistence of a cool spectral component that is apparently very similar to the spectrum of a cool giant, with at least one hot continuum, and emission lines from very different stages of ionization. The cool component dominates the infrared spectrum of S-type symbiotics; it tends to be veiled in this wavelength range by what appears to be excess emission in D-type symbiotics, this excess usually being attributed to circumstellar dust. The hot continuum (or continua) dominates the ultraviolet. X-rays have sometimes also been observed. Another important feature of symbiotic stars that needs to be explained is the variability. Different forms occur, some variability being periodic. This type of variability can, in a few cases, strongly suggest the presence of eclipses of a binary system. One of the most characteristic forms of variability is that characterizing the active phases. This basic form of variation is traditionally associated in the optical with the veiling of the cool spectrum and the disappearance of high-ionization emission lines, the latter progressively appearing (in classical cases, reappearing) later. Such spectral changes recall those of novae, but spectroscopic signatures of the high-ejection velocities observed for novae are not usually detected in symbiotic stars. However, the light curves of the 'symbiotic nova' subclass recall those of novae. We may also mention in this connection that radio observations (or, in a few cases, optical observations) of nebulae indicate ejection from symbiotic stars, with deviations from spherical symmetry. We shall give a historical overview of the proposed models for symbiotic stars and make a critical analysis in the light of the observations of symbiotic stars. We describe the empirical approach to models and use the observational data to diagnose the physical conditions in the symbiotics stars. Finally, we compare the results of this empirical

  8. The Symbiotic Performance of Chickpea Rhizobia Can Be Improved by Additional Copies of the clpB Chaperone Gene.

    PubMed

    Paço, Ana; Brígido, Clarisse; Alexandre, Ana; Mateos, Pedro F; Oliveira, Solange

    2016-01-01

    The ClpB chaperone is known to be involved in bacterial stress response. Moreover, recent studies suggest that this protein has also a role in the chickpea-rhizobia symbiosis. In order to improve both stress tolerance and symbiotic performance of a chickpea microsymbiont, the Mesorhizobium mediterraneum UPM-Ca36T strain was genetically transformed with pPHU231 containing an extra-copy of the clpB gene. To investigate if the clpB-transformed strain displays an improved stress tolerance, bacterial growth was evaluated under heat and acid stress conditions. In addition, the effect of the extra-copies of the clpB gene in the symbiotic performance was evaluated using plant growth assays (hydroponic and pot trials). The clpB-transformed strain is more tolerant to heat shock than the strain transformed with pPHU231, supporting the involvement of ClpB in rhizobia heat shock tolerance. Both plant growth assays showed that ClpB has an important role in chickpea-rhizobia symbiosis. The nodulation kinetics analysis showed a higher rate of nodule appearance with the clpB-transformed strain. This strain also induced a greater number of nodules and, more notably, its symbiotic effectiveness increased ~60% at pH5 and 83% at pH7, compared to the wild-type strain. Furthermore, a higher frequency of root hair curling was also observed in plants inoculated with the clpB-transformed strain, compared to the wild-type strain. The superior root hair curling induction, nodulation ability and symbiotic effectiveness of the clpB-transformed strain may be explained by an increased expression of symbiosis genes. Indeed, higher transcript levels of the nodulation genes nodA and nodC (~3 folds) were detected in the clpB-transformed strain. The improvement of rhizobia by addition of extra-copies of the clpB gene may be a promising strategy to obtain strains with enhanced stress tolerance and symbiotic effectiveness, thus contributing to their success as crop inoculants, particularly under

  9. Local and Systemic Regulation of Plant Root System Architecture and Symbiotic Nodulation by a Receptor-Like Kinase

    PubMed Central

    Huault, Emeline; Laffont, Carole; Wen, Jiangqi; Mysore, Kirankumar S.; Ratet, Pascal; Duc, Gérard; Frugier, Florian

    2014-01-01

    In plants, root system architecture is determined by the activity of root apical meristems, which control the root growth rate, and by the formation of lateral roots. In legumes, an additional root lateral organ can develop: the symbiotic nitrogen-fixing nodule. We identified in Medicago truncatula ten allelic mutants showing a compact root architecture phenotype (cra2) independent of any major shoot phenotype, and that consisted of shorter roots, an increased number of lateral roots, and a reduced number of nodules. The CRA2 gene encodes a Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) that primarily negatively regulates lateral root formation and positively regulates symbiotic nodulation. Grafting experiments revealed that CRA2 acts through different pathways to regulate these lateral organs originating from the roots, locally controlling the lateral root development and nodule formation systemically from the shoots. The CRA2 LRR-RLK therefore integrates short- and long-distance regulations to control root system architecture under non-symbiotic and symbiotic conditions. PMID:25521478

  10. Application of plant genomics for improved symbiotic nitrogen fixation in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because genome sequencing, transcript profiling, proteome analysis, metabolite profiling, mutant analysis, and comparative genomics have progressed at a logarithmic pace, we know more about the plant genes involved in symbiotic nitrogen fixation (SNF) than could have been imagined a decade ago. Howe...

  11. An Analysis on a Negotiation Model Based on Multiagent Systems with Symbiotic Learning and Evolution

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Tofazzal

    This study explores an evolutionary analysis on a negotiation model based on Masbiole (Multiagent Systems with Symbiotic Learning and Evolution) which has been proposed as a new methodology of Multiagent Systems (MAS) based on symbiosis in the ecosystem. In Masbiole, agents evolve in consideration of not only their own benefits and losses, but also the benefits and losses of opponent agents. To aid effective application of Masbiole, we develop a competitive negotiation model where rigorous and advanced intelligent decision-making mechanisms are required for agents to achieve solutions. A Negotiation Protocol is devised aiming at developing a set of rules for agents' behavior during evolution. Simulations use a newly developed evolutionary computing technique, called Genetic Network Programming (GNP) which has the directed graph-type gene structure that can develop and design the required intelligent mechanisms for agents. In a typical scenario, competitive negotiation solutions are reached by concessions that are usually predetermined in the conventional MAS. In this model, however, not only concession is determined automatically by symbiotic evolution (making the system intelligent, automated, and efficient) but the solution also achieves Pareto optimal automatically.

  12. Changes in symbiotic and associative interrelations in a higher plant-bacterial system during space flight

    NASA Astrophysics Data System (ADS)

    Kordyum, V. A.; Man'ko, V. G.; Popova, A. F.; Shcherbak, O. H.; Mashinsky, A. L.; Nguen-Hgue-Thyok

    The miniature cenosis consisting of the water fern Azolla with its associated symbiotic nitrogen-fixing cyanobacterium Anabaena and the concomitant bacteria was investigated. Ecological closure was shown to produce sharp quantitative and qualitative changes in the number and type of concomitant bacteria. Changes in the distribution of bacterial types grown on beef-extract broth after space flight were recorded. Anabaena azollae underwent the most significant changes under spaceflight conditions. Its cell number per Azolla biomass unit increased substantially. Thus closure of cenosis resulted in a weakening of control over microbial development by Azolla. This tendency was augmented by spaceflight factors. Reduction in control exerted by macro-organisms over development of associated micro-organisms must be taken into account in constructing closed ecological systems in the state of weightlessness.

  13. Comparative metagenomic analysis of microcosm structures and lignocellulolytic enzyme systems of symbiotic biomass-degrading consortia.

    PubMed

    Wongwilaiwalin, Sarunyou; Laothanachareon, Thanaporn; Mhuantong, Wuttichai; Tangphatsornruang, Sithichoke; Eurwilaichitr, Lily; Igarashi, Yasuo; Champreda, Verawat

    2013-10-01

    Decomposition of lignocelluloses by cooperative microbial actions is an essential process of carbon cycling in nature and provides a basis for biomass conversion to fuels and chemicals in biorefineries. In this study, structurally stable symbiotic aero-tolerant lignocellulose-degrading microbial consortia were obtained from biodiversified microflora present in industrial sugarcane bagasse pile (BGC-1), cow rumen fluid (CRC-1), and pulp mill activated sludge (ASC-1) by successive subcultivation on rice straw under facultative anoxic conditions. Tagged 16S rRNA gene pyrosequencing revealed that all isolated consortia originated from highly diverse environmental microflora shared similar composite phylum profiles comprising mainly Firmicutes, reflecting convergent adaptation of microcosm structures, however, with substantial differences at refined genus level. BGC-1 comprising cellulolytic Clostridium and Acetanaerobacterium in stable coexistence with ligninolytic Ureibacillus showed the highest capability on degradation of agricultural residues and industrial pulp waste with CMCase, xylanase, and β-glucanase activities in the supernatant. Shotgun pyrosequencing of the BGC-1 metagenome indicated a markedly high relative abundance of genes encoding for glycosyl hydrolases, particularly for lignocellulytic enzymes in 26 families. The enzyme system comprised a unique composition of main-chain degrading and side-chain processing hydrolases, dominated by GH2, 3, 5, 9, 10, and 43, reflecting adaptation of enzyme profiles to the specific substrate. Gene mapping showed metabolic potential of BGC-1 for conversion of biomass sugars to various fermentation products of industrial importance. The symbiotic consortium is a promising simplified model for study of multispecies mechanisms on consolidated bioprocessing and a platform for discovering efficient synergistic enzyme systems for biotechnological application. PMID:23381385

  14. Gut Microbiota-Induced Immunoglobulin G Controls Systemic Infection by Symbiotic Bacteria and Pathogens.

    PubMed

    Zeng, Melody Y; Cisalpino, Daniel; Varadarajan, Saranyaraajan; Hellman, Judith; Warren, H Shaw; Cascalho, Marilia; Inohara, Naohiro; Núñez, Gabriel

    2016-03-15

    The gut microbiota is compartmentalized in the intestinal lumen and induces local immune responses, but it remains unknown whether the gut microbiota can induce systemic response and contribute to systemic immunity. We report that selective gut symbiotic gram-negative bacteria were able to disseminate systemically to induce immunoglobulin G (IgG) response, which primarily targeted gram-negative bacterial antigens and conferred protection against systemic infections by E. coli and Salmonella by directly coating bacteria to promote killing by phagocytes. T cells and Toll-like receptor 4 on B cells were important in the generation of microbiota-specific IgG. We identified murein lipoprotein (MLP), a highly conserved gram-negative outer membrane protein, as a major antigen that induced systemic IgG homeostatically in both mice and humans. Administration of anti-MLP IgG conferred crucial protection against systemic Salmonella infection. Thus, our findings reveal an important function for the gut microbiota in combating systemic infection through the induction of protective IgG. PMID:26944199

  15. Isolation and characterisation of non-anaerobic butanol-producing symbiotic system TSH06.

    PubMed

    Wang, Genyu; Wu, Pengfei; Liu, Ya; Mi, Shuo; Mai, Shuai; Gu, Chunkai; Wang, Gehua; Liu, Hongjuan; Zhang, Jianan; Børresen, Børre Tore; Mellemsæther, Evy; Kotlar, Hans Kristian

    2015-10-01

    Butanol-producing microorganisms are all obligate anaerobes. In this study, a unique symbiotic system TSH06 was isolated to be capable of producing butanol under non-anaerobic condition. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S ribosomal RNA (rRNA) revealed that two strains coexist in TSH06. The two strains were identical to Clostridium acetobutylicum and Bacillus cereus, respectively. They were isolated individually and named as C. acetobutylicum TSH1 and B. cereus TSH2. C. acetobutylicum TSH1 is a butanol-producing, obligate anaerobic strain. Facultative anaerobic B. cereus TSH2 did not possess the ability of butanol production; however, it offered C. acetobutylicum TSH1 the viability under non-anaerobic condition. Moreover, B. cereus TSH2 enhanced butanol yield and speed of fermentation. TSH06 produced 12.97 g/L butanol and 15.39 g/L total solvent under non-anaerobic condition, which is 25 and 24 %, respectively, higher than those of C. acetobutylicum TSH1. In addition, TSH06 produced butanol faster under non-anaerobic condition than under anaerobic condition. Butanol accounted for more than 80 % of total solvent, which is higher than the known report. TSH06 was stable during passage. In all, TSH06 is a promising candidate for industrialisation of biobutanol with high yield, high butanol proportion, easy-handling and time-saving system. These results demonstrated the potential advantage of symbiosis. This study also provides a promising strategy for butanol fermentation. PMID:26272091

  16. A phosphate transport system is required for symbiotic nitrogen fixation by Rhizobium meliloti.

    PubMed Central

    Bardin, S; Dan, S; Osteras, M; Finan, T M

    1996-01-01

    The bacterium Rhizobium meliloti forms N2-fixing root nodules on alfalfa plants. The ndvF locus, located on the 1,700-kb pEXO megaplasmid of R. meliloti, is required for nodule invasion and N2 fixation. Here we report that ndvF contains four genes, phoCDET, which encode an ABC-type transport system for the uptake of Pi into the bacteria. The PhoC and PhoD proteins are homologous to the Escherichia coli phosphonate transport proteins PhnC and PhnD. The PhoT and PhoE proteins are homologous to each other and to the E. coli phosphonate transport protein PhnE. We show that the R. meliloti phoD and phoE genes are induced in response to phosphate starvation and that the phoC promoter contains two elements which are similar in sequence to the PHO boxes present in E. coli phosphate-regulated promoters. The R. meliloti ndvF mutants grow poorly at a phosphate concentration of 2 mM, and we hypothesize that their symbiotic phenotype results from their failure to grow during the nodule infection process. Presumably, the PhoCDET transport system is employed by the bacteria in the soil environment, where the concentration of available phosphate is normally 0.1 to 1 microM. PMID:8755882

  17. The Type III Secretion System of Bradyrhizobium japonicum USDA122 Mediates Symbiotic Incompatibility with Rj2 Soybean Plants

    PubMed Central

    Tsukui, Takahiro; Eda, Shima; Kaneko, Takakazu; Sato, Shusei; Okazaki, Shin; Kakizaki-Chiba, Kaori; Itakura, Manabu; Mitsui, Hisayuki; Yamashita, Akifumi; Terasawa, Kimihiro

    2013-01-01

    The rhcJ and ttsI mutants of Bradyrhizobium japonicum USDA122 for the type III protein secretion system (T3SS) failed to secrete typical effector proteins and gained the ability to nodulate Rj2 soybean plants (Hardee), which are symbiotically incompatible with wild-type USDA122. This suggests that effectors secreted via the T3SS trigger incompatibility between these two partners. PMID:23204412

  18. Evolution of the symbiotic binary system AG Pegasi - The slowest classical nova eruption ever recorded

    NASA Technical Reports Server (NTRS)

    Kenyon, Scott J.; Mikolajewska, Joanna; Mikolajewski, Maciej; Polidan, Ronald S.; Slovak, Mark H.

    1993-01-01

    We present an analysis of new and existing photometric and spectroscopic observations of the ongoing eruption in the symbiotic star AG Pegasi, showing that this binary has evolved considerably since the turn of the century. Recent dramatic changes in both the UV continuum and the wind from the hot component allow a more detailed analysis than in previous papers. AG Peg is composed of a normal M3 giant and a hot, compact star embedded in a dense, ionized nebula. The hot component powers the activity observed in this system, including a dense wind and a photoionized region within the outer atmosphere of the red giant. The hot component contracted in radius at roughly constant luminosity from 1850 to 1985. Its bolometric luminosity declined by a factor of about 4 during the past 5 yr. Both the mass loss rate from the hot component and the emission activity decreased in step with the hot component's total luminosity, while photospheric radiation from the red giant companion remained essentially constant.

  19. [Evolution of Root Nodule Bacteria: Reconstruction of the Speciation Processes Resulting from Genomic Rearrangements in a Symbiotic System].

    PubMed

    Provorov, N A; Andronov, E E

    2016-01-01

    The processes of speciation and macroevolution of root nodule bacteria (rhizobia), based on deep rearrangements of their genomes and occurring in the N₂-fixing symbiotic system, are reconstructed. At the first stage of rhizobial evolution, transformation of free-living diazotrophs (related to Rhodopseudomonas) to symbiotic N₂-fixers (Bradyrhizobium) occurred due to the acquisition of the fix gene system, which is responsible for providing nitrogenase with electrons and reducing equivalents, as well as for oxygen-dependent regulation of nitrogenase synthesis in planta, and then of the nod genes responsible for the synthesis of the lipo- chito-oligosaccharide Nod factors, which induce root nodule development. The subsequent rearrangements of bacterial genomes included: (1) increased volume of hereditary information supported by species, genera (pan-genome), and individual strains; (2) transition from the unitary genome to a multicomponent one; and (3) enhanced levels of bacterial genetic plasticity and horizontal gene transfer, resulting in formation of new genera, of which Mesorhizobium, Rhizobium, and Sinorhizobium are the largest, and of over 100 species. Rhizobial evolution caused by development and diversification of the Nod factor synthesizing systems may result in both increased host specificity range (transition of Bradyrhizobium from autotrophic to symbiotrophic carbon metabolism in interaction with a broad spectrum of legumes) and to its contraction (transition of Rhizobium and Sinorhizobium to "altruistic" interaction with legumes of the galegoid clade). Reconstruction of the evolutionary pathway from symbiotic N₂-fixers to their free-living ancestors makes it possible to initiate the studies based on up-to-date genome screening technologies and aimed at the issues of genetic integration of organisms into supracpecies complexes, ratios of the macro- and microevolutionary mechanisms, and developmetn of cooperative adaptations based on altruistic

  20. Outbursts in Symbiotic Binaries

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Kenyon, Scott J.

    2004-01-01

    Two models have been proposed for the outbursts of symbiotic stars. In the thermonuclear model, outbursts begin when the hydrogen burning shell of a hot white dwarf reaches a critical mass. After a rapid increase in the luminosity and effective temperature, the white dwarf evolves at constant luminosity to lower effective temperatures, remains at optical maximum for several years, and then returns to quiescence along a white dwarf cooling curve. In disk instability models, the brightness rises when the accretion rate from the disk onto the central white dwarf abruptly increases by factors of 5-20. After a few month to several year period at maximum, both the luminosity and the effective temperature of the disk decline as the system returns to quiescence. If most symbiotic stars undergo thermonuclear eruptions, then symbiotics are probably poor candidates for type I supernovae. However, they can then provide approx. 10% of the material which stars recycle back into the interstellar medium. If disk instabilities are the dominant eruption mechanism, symbiotics are promising type Ia candidates but recycle less material into the interstellar medium.

  1. The Stellar Parameters and Evolutionary State of the Primary in the d' Symbiotic System StHα 190

    NASA Astrophysics Data System (ADS)

    Smith, Verne V.; Pereira, Claudio B.; Cunha, Katia

    2001-07-01

    We report on a high-resolution spectroscopic stellar parameter and abundance analysis of a d' symbiotic star: the yellow component of StHα190. This star has recently been discovered, and confirmed here, to be a rapidly rotating (vsini=100+/-10 km s-1) subgiant, or giant, that exhibits radial velocity variations of probably at least 40 km s-1, indicating the presence of a companion (as in many symbiotic systems, the companion is a hot white dwarf star). An analysis of the red spectrum reveals the cool stellar component to have an effective temperature of Teff=5300+/-150 K and a surface gravity of logg=3.0+/-0.5 (this corresponds to an approximate spectral type of G4 III/IV). These parameters result in an estimated primary luminosity of 45 Lsolar, implying a distance of about 780 pc (within a factor of 2). The iron and calcium abundances are found to be close to solar; however, barium is overabundant, relative to Fe and Ca, by about 0.5 dex. The Ba enhancement reflects mass transfer of s-process-enriched material when the current white dwarf was an asymptotic giant branch star, of large physical dimension (>=1 AU). The past and future evolution of this binary system depends critically on its current orbital period, which is not yet known. Concerted and frequent radial velocity measurements are needed to provide crucial physical constraints to this d' symbiotic system. Based on observations made with the 2.1 m telescope of McDonald Observatory, University of Texas.

  2. The puzzling symbiotic X-ray system 4U1700+24

    NASA Astrophysics Data System (ADS)

    Nucita, A. A.; Stefanelli, S.; De Paolis, F.; Masetti, N.; Ingrosso, G.; Del Santo, M.; Manni, L.

    2014-02-01

    Context. Symbiotic X-ray binaries form a subclass of low-mass X-ray binary systems consisting of a neutron star accreting material from a red giant donor star via stellar wind or Roche lobe overflow. Only a few confirmed members are currently known; 4U 1700+24 is a good candidate as it is a relatively bright X-ray object, possibly associated with the late-type star V934 Her. Aims: We analysed the archive XMM-Newton and Swift/XRT observations of 4U 1700+24 in order to have a uniform high-energy (0.3-10 keV) view of the source. Apart from the 2003, 2010, and 2012 data, publicly available but still unpublished, we also took the opportunity to re-analyze a set of XMM-Newton data acquired in 2002. Methods: After reducing the XMM-Newton and Swift/XRT data with standard methods, we performed a detailed spectral and timing analysis. Results: We confirmed the existence of a red-shifted O VIII Ly-α transition (already observed in the 2002 XMM-Newton data) in the high-resolution spectra collected via the RGS instruments. The red-shift of the line is found in all the analysed observations and, on average, it was estimated to be ≃0.009. We also observed a modulation of the centroid energy of the line on short time scales (a few days) and discuss the observations in the framework of different scenarios. If the modulation is due to the gravitational red-shift of the neutron star, it might arise from a sudden re-organization of the emitting X-ray matter on the scale of a few hundreds of km. Alternatively, we are witnessing a uni-polar jet of matter (with typical velocity of 1000-4000 km s-1) possibly emitted by the neutron star in an almost face-on system. The second possibility seems to be required by the apparent lack of any modulation in the observed X-ray light curve. We also note also that the low-resolution spectra (both XMM-Newton and Swift/XRT in the 0.3-10 keV band) show the existence of a black-body radiation emitted by a region (possibly associated with the neutron

  3. The Recent Evolution of a Symbiotic Ion Channel in the Legume Family Altered Ion Conductance and Improved Functionality in Calcium Signaling[C][W

    PubMed Central

    Venkateshwaran, Muthusubramanian; Cosme, Ana; Han, Lu; Banba, Mari; Satyshur, Kenneth A.; Schleiff, Enrico; Parniske, Martin; Imaizumi-Anraku, Haruko; Ané, Jean-Michel

    2012-01-01

    Arbuscular mycorrhiza and the rhizobia-legume symbiosis are two major root endosymbioses that facilitate plant nutrition. In Lotus japonicus, two symbiotic cation channels, CASTOR and POLLUX, are indispensable for the induction of nuclear calcium spiking, one of the earliest plant responses to symbiotic partner recognition. During recent evolution, a single amino acid substitution in DOES NOT MAKE INFECTIONS1 (DMI1), the POLLUX putative ortholog in the closely related Medicago truncatula, rendered the channel solo sufficient for symbiosis; castor, pollux, and castor pollux double mutants of L. japonicus were rescued by DMI1 alone, while both Lj-CASTOR and Lj-POLLUX were required for rescuing a dmi1 mutant of M. truncatula. Experimental replacement of the critical serine by an alanine in the selectivity filter of Lj-POLLUX conferred a symbiotic performance indistinguishable from DMI1. Electrophysiological characterization of DMI1 and Lj-CASTOR (wild-type and mutants) by planar lipid bilayer experiments combined with calcium imaging in Human Embryonic Kidney-293 cells expressing DMI1 (the wild type and mutants) suggest that the serine-to-alanine substitution conferred reduced conductance with a long open state to DMI1 and improved its efficiency in mediating calcium oscillations. We propose that this single amino acid replacement in the selectivity filter made DMI1 solo sufficient for symbiosis, thus explaining the selective advantage of this allele at the mechanistic level. PMID:22706284

  4. The X-ray/radio and UV luminosity expected from symbiotic systems as the progenitor of SNe Ia

    NASA Astrophysics Data System (ADS)

    Meng, Xiangcun; Han, Zhanwen

    2016-04-01

    Context. Symbiotic systems (i.e. a white dwarf + red giant star, WD + RG), which experience mass loss and form circumstellar material (CSM), have been suggested as being a possible progenitor system of type Ia supernovae (SNe Ia). After a supernova explosion, the supernova ejecta may interact with the CSM or the RG secondary. X-ray/radio emission (excess UV photons) is expected from the interaction between supernova ejecta and the CSM (RG secondary). However, no X-ray or radio emission that has originated from this type of system has been observationally detected, and only four SNe Ia have shown any possible signal of excess UV emission. These observational discrepancies need to be interpreted. Aims: We seek to determine the luminosity of these emissions, using detailed binary evolution algorithms to obtain the parameters of binary systems at the moment of the supernova explosion. Methods: We carried out a series of binary stellar evolution calculations, in which the effect of tidally enhanced wind on the evolution of WD + RG systems is incorporated. The WDs increase their mass to the Chandrasekhar mass limit, and then explode as SNe Ia. Based on the binary evolution results, we estimated the X-ray/radio (the excess UV) luminosity from the interactions between supernova ejecta and the CSM (the secondary) using a variety of published standard models. Results: We found that the X-ray flux may be high enough to be detected for a nearby SN Ia from a symbiotic system, while the radio flux is more likely to de detected when the companion is an asymptotic giant branch (AGB) star, and for a first giant branch (FGB) companion, the radio flux is generally lower than the detection limit. For two well observed SNe Ia, 2011fe and 2014J, almost all symbiotic systems are excluded by X-ray observations, but WD + FGB systems may not be ruled out by radio observations. The excess UV luminosity that results from the collision of supernova ejecta with the RG secondary may be high

  5. Physical Structure of Four Symbiotic Binaries

    NASA Technical Reports Server (NTRS)

    Kenyon, Scott J. (Principal Investigator)

    1997-01-01

    Disk accretion powers many astronomical objects, including pre-main sequence stars, interacting binary systems, and active galactic nuclei. Unfortunately, models developed to explain the behavior of disks and their surroundings - boundary layers, jets, and winds - lack much predictive power, because the physical mechanism driving disk evolution - the viscosity - is not understood. Observations of many types of accreting systems are needed to constrain the basic physics of disks and provide input for improved models. Symbiotic stars are an attractive laboratory for studying physical phenomena associated with disk accretion. These long period binaries (P(sub orb) approx. 2-3 yr) contain an evolved red giant star, a hot companion, and an ionized nebula. The secondary star usually is a white dwarf accreting material from the wind of its red giant companion. A good example of this type of symbiotic is BF Cygni: our analysis shows that disk accretion powers the nuclear burning shell of the hot white dwarf and also manages to eject material perpendicular to the orbital plane (Mikolajewska, Kenyon, and Mikolajewski 1989). The hot components in other symbiotic binaries appear powered by tidal overflow from a very evolved red giant companion. We recently completed a study of CI Cygni and demonstrated that the accreting secondary is a solar-type main sequence star, rather than a white dwarf (Kenyon et aL 1991). This project continued our study of symbiotic binary systems. Our general plan was to combine archival ultraviolet and optical spectrophotometry with high quality optical radial velocity observations to determine the variation of line and continuum sources as functions of orbital phase. We were very successful in generating orbital solutions and phasing UV+optical spectra for five systems: AG Dra, V443 Her, RW Hya, AG Peg, and AX Per. Summaries of our main results for these systems appear below. A second goal of our project was to consider general models for the

  6. Chemical Abundances of Symbiotic Giants

    NASA Astrophysics Data System (ADS)

    Gałan, C.; Mikołajewska, J.; Hinkle, K. H.; Joyce, R. R.

    2015-12-01

    High resolution (R ˜ 50000), near-IR spectra were used to measure photospheric abundances of CNO and elements around the iron peak for 24 symbiotic giants. Spectrum synthesis was employed using local thermal equilibrium and hydrostatic model atmospheres. The metallicities are distributed in a wide range with maximum around [Fe/H] ˜-0.4 - - 0.3 dex. Enrichment in 14N indicates that all the sample giants have experienced the first dredge-up. The relative abundance of [Ti/Fe] is generally large in red symbiotic systems.

  7. Evidence signaling the start of enhanced counterjet flow in the symbiotic system R AquarII

    NASA Technical Reports Server (NTRS)

    Michalitsianos, A. G.; Perez, M.; Kafatos, M.

    1994-01-01

    The velocity struture of strong far-UV emission lines observed in the symbiotic variable R Aqr suggests the start of new jet activity which will probably culminate in the appearance of a series of intense nebular emission knots within a decade. This is indicated by a systematic redward wavelength drift of emission lines, which we have followed with the International Ultraviolet Explorer (IUE) since the discovery of the brilliant northeast jet emission knots more than 10 years ago. The C IV wavelengths 1548, 1550 resonance lines, which previously showed a prominent blue asymmetric wing that extended to velocities in excess -200 km/s, exhibit red wing asymmetry that extends to speeds of approximately +200 km/s in late 1992. The C IV line profile structure is consistent with the model proposed by Solf (1993), who explains the appearance of the northeast jet knots in terms of a approximately 300-500 km/s collimated wind that collides with slower moving material expelled earlier in a nova outburst that occurred approximately 190 yr ago. Based upon these high-resolution UV spectra, similar emission structues should appear southwest of the central star when the counterwind (or stream) interacts with material in the southwest inner nebula. The apparent change in direction of flow could result from a precessing accretion disk that alters the projection angle of collimated flow from the disk poles. The direction of the collimated wind may be related to the binary orbit, because the velocity shifts associated with emission lines formed in the flow change direction on a timescale which is comparable to the binary period.

  8. Outbursts in Symbiotic Binaries

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Keyes, Charles

    2005-01-01

    A major question for symbiotic stars concerns the nature and cause of their outbursts. A small subset of symbiotics, the slow novae are fairly well established as thermonuclear events that last on the order of decades. The several symbiotic recurrent novae, which are much shorter and last on the order of months, are also thought to be thermonuclear runaways. Yet the majority of symbiotics are neither slow novae nor recurrent novae. These are the so-called classical symbiotics, many of which show outbursts whose cause is not well understood. In some cases, jets are produced in association with an outburst, therefore an investigation into the causes of outbursts will yield important insights into the production of collimated outflows. To investigate the cause and nature of classical symbiotic outbursts, we initiated a program of multiwavelength observations of these events. In FUSE Cycle 2, we obtained six observational epochs of the 2000-2002 classic symbiotic outburst in the first target of our campaign - class prototype, Z Andromedae. That program was part of a coordinated multi-wavelength Target-of-Opportunity (TOO) campaign with FUSE, XMM, Chandra, MERLIN, the VLA, and ground-based spectroscopic and high time-resolution photometric observations. Our campaign proved the concept, utility, and need for coordinated multi-wavelength observations in order to make progress in understanding the nature of the outburst mechanisms in symbiotic stars. Indeed, the FUSE data were the cornerstone of this project

  9. Infrared studies of Nova Scorpii 2014: an outburst in a symbiotic system sans an accompanying blast wave

    NASA Astrophysics Data System (ADS)

    Joshi, Vishal; Banerjee, D. P. K.; Ashok, N. M.; Venkataraman, V.; Walter, F. M.

    2015-10-01

    Near-IR (NIR) spectroscopy is presented for Nova Scorpii 2014. It is shown that the outburst occurred in a symbiotic binary system - an extremely rare configuration for a classical nova outburst to occur in but appropriate for the eruption of a recurrent nova of the T CrB class. We estimate the spectral class of secondary as M5III ± (two sub-classes). The maximum magnitude versus rate of decline relations give an unacceptably large value of 37.5 kpc for the distance. The spectra are typical of the He/N class of novae with strong He I and H lines. The profiles are broad and flat topped with full width at zero intensities approaching 9000-10 000 km s-1 and also have a sharp narrow component superposed which is attributable to emission from the giant's wind. Hot shocked gas, accompanied by X-rays and γ-rays, is expected to form when the high-velocity ejecta from the nova ploughs into the surrounding giant wind. Although X-ray emission was observed no γ-ray emission was reported. It is also puzzling that no signature of a decelerating shock is seen in the NIR, seen in similar systems like RS Oph, V745 Sco and V407 Cyg, as rapid narrowing of the line profiles. The small outburst amplitude and the giant secondary strongly suggest that Nova Sco 2014 could be a recurrent nova.

  10. Outbursts in Symbiotic Binaries

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Kenyon, Scott J.

    2003-01-01

    Two models have been proposed for the outbursts of symbiotic stars. In the thermonuclear model, outbursts begin when the hydrogen burning shell of a hot white dwarf reaches a critical mass. After a rapid increase in the luminosity and effective temperature, the white dwarf evolves at constant luminosity to lower effective temperatures, remains at optical maximum for several years, and then returns to quiescence along a white dwarf cooling curve. In disk instability models, the brightness rises when the accretion rate from the disk onto the central white dwarf abruptly increases by factors of 5-20. After a few month to several year period at maximum, both the luminosity and the effective temperature of the disk decline as the system returns to quiescence.

  11. Systems of symbiotic large FBRs and small CANDLE-Thorium-HTGRs

    SciTech Connect

    Ismail; Liem, P. H.; Takaki, N.; Sekimoto, H.

    2006-07-01

    Multi-component nuclear system is a system in which several types of nuclear reactors and related fuel cycle facilities are operated with mutual material exchange. A mainstay of the system is a centralized nuclear park that consists of large-scale FBRs and nuclear fuel facilities for fabrication, reprocessing and cooling/storage of nuclear fuels. The role of the FBRs is simultaneously to produce electricity and support small satellite-reactors by providing nuclear fuel. The satellite-reactors can supply energy to remote small areas. In the present study, natural uranium and thorium are charged into the FBRs in distinct fuel pin types. Under the equilibrium state, the fuels are continually discharged and separated with a certain discharge constant. Actinides, excluding {sup 233}U-only or uranium-element, are returned to the FBRs while discharged-uranium is used for fresh fuels of small HTGR thorium cycle satellite-reactors. Fissile support capability of the FBR to the satellite-reactors is investigated as function of both the FBR uranium-thorium fraction and uranium discharge constant parameters. The system shows that larger number of uranium pins is better for the FBR criticality while larger number of thorium pins and larger uranium discharge constant give better support capability. (authors)

  12. An interdisciplinary research strategy to improve symbiotic nitrogen fixation and yield of common bean (Phaseolus vulgaris) in salinised areas of the Mediterranean basin.

    PubMed

    Drevon, J J; Abdelly, C; Amarger, N; Aouani, E A; Aurag, J; Gherbi, H; Jebara, M; Lluch, C; Payre, H; Schump, O; Soussi, M; Sifi, B; Trabelsi, M

    2001-10-01

    The main findings of a cooperative research group of agronomists, plant breeders, microbiologists, physiologists and molecularists to improve the symbiotic nitrogen fixation (SNF) and N2-dependent yield of common bean under moderate salinity in the Mediterranean basin are summarised. Agronomic surveys in reference production areas show large spatial and temporal variations in plant nodulation and growth, and in efficiency of utilisation of the rhizobial symbiosis. The latter was associated with a large rhizobial diversity, including new bean nodulating species. Macrosymbiont diversity in SNF and adaptation to NaCl was found. However, contrasts between plant genotypes could be altered by specific interactions with some native rhizobia. Therefore, variations in soil rhizobial population, in addition to agronomic practices and environmental constraints, may have contributed to erratic results observed in field inoculations. At the mechanistic level, nodule C and N metabolisms, and abcissic acid content, were related to SNF potential and tolerance to NaCl. Their relation with nodule conductance to O2 diffusion was addressed by in situ hybridisation of candidate carbonic anhydrase and aquaporin genes in nodule cortex. The limits and prospects of the cooperative strategy are discussed. PMID:11566396

  13. A synergistic interaction between salt-tolerant Pseudomonas and Mesorhizobium strains improves growth and symbiotic performance of liquorice (Glycyrrhiza uralensis Fish.) under salt stress.

    PubMed

    Egamberdieva, Dilfuza; Li, Li; Lindström, Kristina; Räsänen, Leena A

    2016-03-01

    Chinese liquorice (Glycyrrhiza uralensis Fish.) is a salt-tolerant medicinal legume that could be utilized for bioremediation of salt-affected soils. We studied whether co-inoculation of the symbiotic Mesorhizobium sp. strain NWXJ19 or NWXJ31 with the plant growth-promoting Pseudomonas extremorientalis TSAU20 could restore growth, nodulation, and shoot/root nitrogen contents of salt-stressed G. uralensis, which was grown in potting soil and irrigated with 0, 50, and 75 mM NaCl solutions under greenhouse conditions. Irrigation with NaCl solutions clearly retarded the growth of uninoculated liquorice, and the higher the NaCl concentration (75 and 100 mM NaCl), the more adverse is the effect. The two Mesorhizobium strains, added either alone or in combination with P. extremorientalis TSAU20, responded differently to the salt levels used. The strain NWXJ19 was a good symbiont for plants irrigated with 50 mM NaCl, whereas the strain NWXJ31 was more efficient for plants irrigated with water or 75 mM NaCl solution. P. extremorientalis TSAU20 combined with single Mesorhizobium strains alleviated the salt stress of liquorice plants and improved yield and nodule numbers significantly in comparison with single-strain-inoculated liquorice. Both salt stress and inoculation raised the nitrogen content of shoots and roots. The nitrogen contents were at their highest, i.e., 30 and 35 % greater compared to non-stressed uninoculated plants, when plants were inoculated with P. extremorientalis TSAU20 and Mesorhizobium sp. NWXJ31 as well as irrigated with 75 mM NaCl solution. From this study, we conclude that dual inoculation with plant growth-promoting rhizobacteria could be a new approach to improve the tolerance of G. uralensis to salt stress, thereby improving its suitability for the remediation of saline lands. PMID:26585446

  14. The Sexual and Mating System of the Shrimp Odontonia katoi (Palaemonidae, Pontoniinae), a Symbiotic Guest of the Ascidian Polycarpa aurata in the Coral Triangle

    PubMed Central

    Baeza, J. Antonio; Hemphill, Carrie A.; Ritson-Williams, Raphael

    2015-01-01

    Theory predicts that monogamy is adaptive in symbiotic crustaceans inhabiting relatively small and morphologically simple hosts in tropical environments where predation risk away from hosts is high. We tested this prediction in the shrimp Odontonia katoi, which inhabits the atrial chamber of the ascidian Polycarpa aurata in the Coral Triangle. Preliminary observations in O. katoi indicated that males were smaller than females, which is suggestive of sex change (protandry) in some symbiotic organisms. Thus, we first investigated the sexual system of O. katoi to determine if this shrimp was sequentially hermaphroditic. Morphological identification and size frequency distributions indicated that the population comprised males that, on average, were smaller than females. Gonad dissections demonstrated the absence of transitional individuals. Thus, O. katoi is a gonochoric species with reverse sexual dimorphism. The population distribution of O. katoi in its ascidian host did not differ significantly from a random distribution and shrimps inhabiting the same host individual as pairs were found with a frequency similar to that expected by chance alone. This is in contrast to that reported for other socially monogamous crustaceans in which pairs of heterosexual conspecifics are found in host individuals more frequently than expected by chance alone. Thus, the available information argues against monogamy in O. katoi. Furthermore, that a high frequency of solitary females were found brooding embryos and that the sex ratio was skewed toward females suggests that males might be roaming among hosts in search of receptive females in O. katoi. Symbiotic crustaceans can be used as a model system to understand the adaptive value of sexual and mating systems in marine invertebrates. PMID:25799577

  15. The sexual and mating system of the shrimp Odontonia katoi (Palaemonidae, Pontoniinae), a symbiotic guest of the ascidian Polycarpa aurata in the Coral Triangle.

    PubMed

    Baeza, J Antonio; Hemphill, Carrie A; Ritson-Williams, Raphael

    2015-01-01

    Theory predicts that monogamy is adaptive in symbiotic crustaceans inhabiting relatively small and morphologically simple hosts in tropical environments where predation risk away from hosts is high. We tested this prediction in the shrimp Odontonia katoi, which inhabits the atrial chamber of the ascidian Polycarpa aurata in the Coral Triangle. Preliminary observations in O. katoi indicated that males were smaller than females, which is suggestive of sex change (protandry) in some symbiotic organisms. Thus, we first investigated the sexual system of O. katoi to determine if this shrimp was sequentially hermaphroditic. Morphological identification and size frequency distributions indicated that the population comprised males that, on average, were smaller than females. Gonad dissections demonstrated the absence of transitional individuals. Thus, O. katoi is a gonochoric species with reverse sexual dimorphism. The population distribution of O. katoi in its ascidian host did not differ significantly from a random distribution and shrimps inhabiting the same host individual as pairs were found with a frequency similar to that expected by chance alone. This is in contrast to that reported for other socially monogamous crustaceans in which pairs of heterosexual conspecifics are found in host individuals more frequently than expected by chance alone. Thus, the available information argues against monogamy in O. katoi. Furthermore, that a high frequency of solitary females were found brooding embryos and that the sex ratio was skewed toward females suggests that males might be roaming among hosts in search of receptive females in O. katoi. Symbiotic crustaceans can be used as a model system to understand the adaptive value of sexual and mating systems in marine invertebrates. PMID:25799577

  16. Forbidden high excitation lines and TiO bands in the symbiotic system QW SGE = MH-alpha 80-5

    NASA Astrophysics Data System (ADS)

    Calabro, E.; Mammano, A.

    1992-11-01

    The suspected symbiotic nature of MH-alpha 80-5 = AS 360 was confirmed for the first time by spectra taken in 1967 at Asiago Observatory (Marini, 1969) showing the O III and Ne III forbidden lines, together with strong He II lines and TiO bands. According to Allen (1984) nebular lines were absent in 1978, while we recorded them again in 1985. Further excitation strengthening up to forbidden Fe VII and O VI, in 1990 were noted by Munari and Buson (1991). The evolution implies density variability in the thick nebula surrounding this new variable system.

  17. Infrared Spectroscopy of Symbiotic Stars. X. Orbits for Three S-type Systems: V1044 Centauri, Hen 3-1213, and SS 73-96

    NASA Astrophysics Data System (ADS)

    Fekel, Francis C.; Hinkle, Kenneth H.; Joyce, Richard R.; Wood, Peter R.

    2015-08-01

    Employing new infrared radial velocities, we have computed orbits of the cool giants in three southern S-type symbiotic systems. The orbit for V1044 Cen, an M5.5 giant, has a period of 985 days and a modest eccentricity of 0.16. Hen 3-1213 is a K4 giant, yellow symbiotic with an orbital period of 533 days and a similar eccentricity of 0.18. For the M2 giant SS 73-96 the orbital period is 828 days, and this system has a somewhat larger eccentricity of 0.26. Measurement of the H i Paschen δ emission lines, which may at least partially reflect the motion of the secondary in SS 73-96, results in a mass ratio of 2.4 for the M giant relative to the presumed white dwarf. The estimated orbital inclinations of V1044 Cen and Hen 3-1213 are low, about 40°. However, for SS 73-96 the predicted inclination is 90°, and so an ephemeris for eclipses of the secondary or the hot nebula surrounding it is provided. A search of the orbital velocity residuals of V1044 Cen and SS 73-96 for pulsation periods produced no realistic or convincing period for either star.

  18. Symbiotic stars in X-rays

    NASA Astrophysics Data System (ADS)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2013-11-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of nine white dwarf symbiotics that were not previously known to be X-ray sources and one that had previously been detected as a supersoft X-ray source. The nine new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. The Swift/XRT telescope detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component that we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component that probably originates in a region where low-velocity shocks produce X-ray emission, i.e., a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the α/β/γ classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new δ classification

  19. Symbiotic Stars in X-rays

    NASA Technical Reports Server (NTRS)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2014-01-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

  20. Towards Whole System Improvement

    ERIC Educational Resources Information Center

    Glatter, Ron

    2012-01-01

    The relationship between academies, and school autonomy more generally, and the wider system is a crucial issue in the battle to improve school-level education. International experience indicates that emphasising choice and competition to drive improvement is not effective and that changing structures does not yield better results for students. A…

  1. The enigmatic life history of the symbiotic crab Tunicotheres moseri (Crustacea, Brachyura, Pinnotheridae): implications for its mating system and population structure.

    PubMed

    Hernández, J E; Bolaños, J A; Palazón, J L; Hernández, G; Lira, C; Baeza, J Antonio

    2012-12-01

    Resource-monopolization theory predicts the adoption of a solitary habit in species using scarce, discrete, and small refuges. Life-history theory suggests that temporarily stable parental dwellings favor extended parental care in species that brood embryos. We tested these two predictions with the symbiotic crab Tunicotheres moseri. This species exhibits abbreviated development and inhabits the atrial chamber of the scarce, structurally simple, long-lived, and relatively small ascidian Phalusia nigra in the Caribbean. These host characteristics should favor a solitary habit and extended parental care (EPC) in T. moseri. As predicted, males and females of T. moseri inhabited ascidians solitarily with greater frequency than expected by chance alone. The male-female association pattern and reverse sexual dimorphism (males < females) additionally suggests a promiscuous "pure-search" mating system in T. moseri. Also in agreement with theoretical considerations, T. moseri displays EPC; in addition to embryos, females naturally retain larval stages, megalopae, and juveniles within their brooding pouches. This is the first record of EPC in a symbiotic crab and the second confirmed record of EPC in a marine brachyuran crab. This study supports predictions central to resource-monopolization and life-history theories. PMID:23264474

  2. A New Look at the Symbiotic Star RW Hydrae

    NASA Astrophysics Data System (ADS)

    Otulakowska-Hypka, M.; Mikolajewska, J.; Whitelock, P. A.

    2014-12-01

    We present new estimates of the basic stellar parameters of the non-eruptive, eclipsing symbiotic system, RW Hydrae. A set of photometric and spectroscopic data was used to model this object simultaneously from the light and radial velocity curves. With new spectroscopic data we were able to improve previous results known from the literature and derive physical parameters of the system: q=4.2, M1=0.8 M⊙, M2=3.4 M⊙, R1=0.2 R⊙, R2=145 R⊙, a=350 R⊙, and i=75°.

  3. SS 383: A NEW S-TYPE YELLOW SYMBIOTIC STAR?

    SciTech Connect

    Baella, N. O.; Pereira, C. B.; Miranda, L. F.

    2013-11-01

    Symbiotic stars are key objects in understanding the formation and evolution of interacting binary systems, and are probably the progenitors of Type Ia supernovae. However, the number of known symbiotic stars is much lower than predicted. We aim to search for new symbiotic stars, with particular emphasis on the S-type yellow symbiotic stars, in order to determine their total population, evolutionary timescales, and physical properties. The Two Micron All Sky Survey (2MASS) (J – H) versus (H – K {sub s}) color-color diagram has been previously used to identify new symbiotic star candidates and show that yellow symbiotics are located in a particular region of that diagram. Candidate symbiotic stars are selected on the basis of their locus in the 2MASS (J – H) versus (H – K {sub s}) diagram and the presence of Hα line emission in the Stephenson and Sanduleak Hα survey. This diagram separates S-type yellow symbiotic stars from the rest of the S-type symbiotic stars, allowing us to select candidate yellow symbiotics. To establish the true nature of the candidates, intermediate-resolution spectroscopy is obtained. We have identified the Hα emission line source SS 383 as an S-type yellow symbiotic candidate by its position in the 2MASS color-color diagram. The optical spectrum of SS 383 shows Balmer, He I, He II, and [O III] emission lines, in combination with TiO absorption bands that confirm its symbiotic nature. The derived electron density (≅10{sup 8-9} cm{sup –3}), He I emission line intensity ratios, and position in the [O III] λ5007/Hβ versus [O III] λ4363/Hγ diagram indicate that SS 383 is an S-type symbiotic star, with a probable spectral type of K7-M0 deduced for its cool component based on TiO indices. The spectral type and the position of SS 383 (corrected for reddening) in the 2MASS color-color diagram strongly suggest that SS 383 is an S-type yellow symbiotic. Our result points out that the 2MASS color-color diagram is a powerful tool in

  4. The first symbiotic stars from the LAMOST survey

    NASA Astrophysics Data System (ADS)

    Li, Jiao; Mikołajewska, Joanna; Chen, Xue-Fei; Luo, A.-Li; Rebassa-Mansergas, Alberto; Hou, Yong-Hui; Wang, Yue-Fei; Wu, Yue; Yang, Ming; Zhang, Yong; Han, Zhan-Wen

    2015-08-01

    Symbiotic stars are interacting binary systems with the longest orbital periods. They are typically formed by a white dwarf and a red giant that are embedded in a nebula. These objects are natural astrophysical laboratories for studying the evolution of binaries. Current estimates of the population of symbiotic stars in the Milky Way vary from 3000 up to 400 000. However, a current census has found less than 300. The Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) survey can obtain hundreds of thousands of stellar spectra per year, providing a good opportunity to search for new symbiotic stars. We detect four such binaries among 4 147 802 spectra released by LAMOST, of which two are new identifications. The first is LAMOST J12280490-014825.7, considered to be an S-type halo symbiotic star. The second is LAMOST J202629.80+423652.0, a D-type symbiotic star.

  5. Improved solar heating systems

    DOEpatents

    Schreyer, J.M.; Dorsey, G.F.

    1980-05-16

    An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

  6. Improved vortex reactor system

    DOEpatents

    Diebold, James P.; Scahill, John W.

    1995-01-01

    An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

  7. Improved ranging systems

    NASA Technical Reports Server (NTRS)

    Young, Larry E.

    1989-01-01

    Spacecraft range measurements have provided the most accurate tests, to date, of some relativistic gravitational parameters, even though the measurements were made with ranging systems having error budgets of about 10 meters. Technology is now available to allow an improvement of two orders of magnitude in the accuracy of spacecraft ranging. The largest gains in accuracy result from the replacement of unstable analog components with high speed digital circuits having precisely known delays and phase shifts.

  8. Improved vortex reactor system

    DOEpatents

    Diebold, J.P.; Scahill, J.W.

    1995-05-09

    An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

  9. Population control in symbiotic corals

    SciTech Connect

    Falkowski, P.G. ); Dubinsky, Z. ); Muscatine, L. ); McCloskey, L. )

    1993-10-01

    Stability in symbiotic association requires control of population growth between symbionts. The population density of zooxanthellae per unit surface area of most symbiotic corals is remarkably consistant. How is the population density of zooxanthellae maintained and what happens to the symbiotic association if the balance between algae and host is perturbed. The answers to these question, examined in this paper, provide a framework for understanding how the size of the component populations is controlled in symbiotic associations. The topic areas covered include the following: carbon economy in a symbiotic coral; effects of nutrient enrichment; the chemostat model of population control; the effects of exposure to ammonium levels. Ammonium ions and organic materials are the factors which maintain the density of zooxanthellae. 32 refs., 5 figs.

  10. Outbursts in Symbiotic Binaries: Z and Continued Observation

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Keyes, Charles

    2005-01-01

    A major question for symbiotic stars concerns the nature and cause of their outbursts. A small subset of symbiotics, the "slow novae" are fairly well established as thermonuclear events that last on the order of decades. The several symbiotic "recurrent novae", which are much shorter and last on the order of months, are also thought to be thermonuclear runaways. Yet the majority of symbiotics are neither slow novae nor recurrent novae. These are the so-called "classical symbiotics," many of which show outbursts whose cause is not well understood. In some cases, jets are produced in association with an outburst, therefore an investigation into the causes of outbursts will yield important insights into the production of collimated outflows. To investigate the cause and nature of classical symbiotic outbursts, we initiated a program of multi- wavelength observations of these events. First of all in FUSE Cycle 2, we obtained six observational epochs of the 2000-2002 classic symbiotic outburst in the first target of our campaign - class prototype, Z Andromedae. That program was part of a coordinated multi-wavelength Target-of-Opportunity (TOO) campaign with FUSE, XMM, Chandra, MERLIN, the VLA, and ground-based spectroscopic and high time-resolution photometric observations. Our campaign proved the concept, utility, and need for coordinated multi-wavelength observations in order to make progress in understanding the nature of the outburst mechanisms in symbiotic stars. Indeed, the FUSE data were the cornerstone of this project. The present program is a continuation of that cycle 2 effort. Indeed, the observations acquired in this program are vital to the proper interpretation of the material acquired in cycle 2 as the new data cover the critical time period when the star continues to decline from outburst and actually returns to quiescence. The utilization of these data have allowed us to refine and complete description of our new model for classical symbiotic system

  11. Improving Communications Systems

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle has many communications systems which are used throughout a typical mission. Given that the radio spectrum has become increasingly congested, the ability to hear extremely weak signals requires greater receiver sensitivity. Dryden Flight Research Center approached Angle Linear, a manufacturer of linear radio frequency products and peripherals for communications, to solve the problem. The solution was a receiving preamplifier specially crafted for NASA. Communications with the Space Shuttle are now more reliable,with Dryden being able to also support local missions without purchasing additional equipment. The work has carried over into the Mir Space Station communication support effort and is under evaluation by other NASA centers. The company's preamplifier line was greatly expanded to cover a broader range of frequencies, providing the same sensational improvement to other areas of communication including business, government, trucking, land mobile, cellular and broadcast.

  12. BPM System Improvements

    SciTech Connect

    Church, M.

    1991-04-24

    During the accelerator studies period of 12/90 through 1/91 the Accumulator BPM system was investigated in some detail in an effort to improve its reliability and accuracy in making closed orbit measurements. The motivation for this is to try and improve the beam energy resolution for E760. The relativistic {beta} of the {bar p} is given by {beta} = f{sub R}L/c where f{sub R} is the revolution frequency, L is the orbit length ({approx} 474050mm), and c is the speed of light. Hence, the error in {beta} is given by d{beta}/{beta} = df{sub R}/f{sub R} + dL/L. Since df{sub R}/f{sub R} is {approx} 2 x 10{sup -7}, the main contribution to the error comes from dL. During the E760 run of 5/90 to 9/90 dL was estimated to be {approx} 1mm. It is thought that this can be reduced to {approx} .25mm with proper use of the present BPM system. L is given by L = L{sub 0} + {delta}L where L{sub 0} is the accurately known orbit length of a reference orbit (extracted from an energy scan of the J/{Psi} or {Psi}{prime}), and {delta}L is the difference orbit between the current orbit and the reference orbit. SL is calculated in the 1st approximation by {delta}L = {Sigma}{sub i}C{sub i}{Sigma}{sub j}{Delta}BPM{sub ij} where {Delta}BPM{sub ij} is the horizontal difference orbit at the ith BPM in the jth sector and C{sub i} are constants depending upon the location of the BPM pickup and the strength of the quadrupoles. Table I lists the constants C{sub i}, and Fig. 1 shows a typical difference orbit, {Delta}BPM{sub ij}. These studies were all done with 'reverse protons' and concentrated on closed orbit measurements with the Accumulator horizontal BPMs. The low frequency (H=2) mode of the BPM system is used in all cases, therefore it is required that the beam be bunched with ARF3 at some level. The low frequency RF module in the BPM system had previously been modified to track the H=2 frequency.

  13. Stress as a Normal Cue in the Symbiotic Environment.

    PubMed

    Schwartzman, Julia A; Ruby, Edward G

    2016-05-01

    All multicellular hosts form associations with groups of microorganisms. These microbial communities can be taxonomically diverse and dynamic, and their persistence is due to robust, and sometimes coevolved, host-microbe and microbe-microbe interactions. Chemical and physical sources of stress are prominently situated in this molecular exchange, as cues for cellular responses in symbiotic microbes. Stress in the symbiotic environment may arise from three sources: host tissues, microbe-induced immune responses, or other microbes in the host environment. The responses of microbes to these stresses can be general or highly specialized, and collectively may contribute to the stability of the symbiotic system. In this review, we highlight recent work that emphasizes the role of stress as a cue in the symbiotic environment of plants and animals. PMID:27004825

  14. Improved multisphere spectrometer system

    SciTech Connect

    Shonka, J.J.; Schwahn, S.O.; Rogers, P.E.; Misko, C.J.

    1991-01-01

    Shonka Research Associated undertook a research program to improve the capabilities and ease of use of the Bonner sphere spectrometer system. Two key elements formed the heart of this research: replacement of the lithium iodide (LiI(Eu)) detector normally used in the spectrometer system with a spherical boron triflouride (BF{sub 3}) proportional counter and exploitation of an optimized set of nested polyethylene spheres, including boron-loaded spherical shells. Use of a spherical BF{sub 3} detector offers many advantages over the LiI(Eu) crystal. The BF{sub 3} detectors are insensitive to gamma radiation. Lack of gamma sensitivity permits acquiring data with simple electronics and allows determination of neutron spectra and dose in lower neutron-to-gamma ratio fields, including background terrestrial radiation fields. The importance of the lack of gamma sensitivity is underscored by the pending changes in neutron quality factors. The nearly perfect spherical symmetry offers advantages for BF{sub 3} over LiI(Eu) detectors as well. A light pipe, which perturbs measurements, is not needed. The bare BF{sub 3} detector response is not affected by the moderation of neutrons as is the case of the organic light pipe used with LiI(Eu). The spherical symmetry permits the use of smaller diameter shells, which add to the number of response functions.

  15. DT2008: A Promising New Genetic Resource for Improved Drought Tolerance in Soybean When Solely Dependent on Symbiotic N2 Fixation

    PubMed Central

    Sulieman, Saad; Ha, Chien Van; Nasr Esfahani, Maryam; Watanabe, Yasuko; Nishiyama, Rie; Pham, Chung Thi Bao; Nguyen, Dong Van; Tran, Lam-Son Phan

    2015-01-01

    Water deficit is one of the major constraints for soybean production in Vietnam. The soybean breeding research efforts conducted at the Agriculture Genetics Institute (AGI) of Vietnam resulted in the development of promising soybean genotypes, suitable for the drought-stressed areas in Vietnam and other countries. Such a variety, namely, DT2008, was recommended by AGI and widely used throughout the country. The aim of this work was to assess the growth of shoots, roots, and nodules of DT2008 versus Williams 82 (W82) in response to drought and subsequent rehydration in symbiotic association as a means to provide genetic resources for genomic research. Better shoot, root, and nodule growth and development were observed in the cultivar DT2008 under sufficient, water deficit, and recovery conditions. Our results represent a good foundation for further comparison of DT2008 and W82 at molecular levels using high throughput omic technologies, which will provide huge amounts of data, enabling us to understand the genetic network involved in regulation of soybean responses to water deficit and increasing the chances of developing drought-tolerant cultivars. PMID:25685802

  16. Microbiome change by symbiotic invasion in lichens.

    PubMed

    Wedin, Mats; Maier, Stefanie; Fernandez-Brime, Samantha; Cronholm, Bodil; Westberg, Martin; Grube, Martin

    2016-05-01

    Lichens are obligate symbioses between fungi and green algae or cyanobacteria. Most lichens resynthesize their symbiotic thalli from propagules, but some develop within the structures of already existing lichen symbioses. Diploschistes muscorum starts as a parasite infecting the lichen Cladonia symphycarpa and gradually develops an independent Diploschistes lichen thallus. Here we studied how this process influences lichen-associated microbiomes and photobionts by sampling four transitional stages, at sites in Sweden and Germany, and characterizing their microbial communities using high-throughput 16S rRNA gene and photobiont-specific ITS rDNA sequencing, and fluorescence in situ hybridization. A gradual microbiome shift occurred during the transition, but fractions of Cladonia-associated bacteria were retained during the process of symbiotic reorganization. Consistent changes observed across sites included a notable decrease in the relative abundance of Alphaproteobacteria with a concomitant increase in Betaproteobacteria. Armatimonadia, Spartobacteria and Acidobacteria also decreased during the infection of Cladonia by Diploschistes. The lichens differed in photobiont specificity. Cladonia symphycarpa was associated with the same algal species at all sites, but Diploschistes muscorum had a flexible strategy with different photobiont combinations at each site. This symbiotic invasion system suggests that partners can be reorganized and selected for maintaining potential roles rather than depending on particular species. PMID:26310431

  17. 3D Models of Symbiotic Binaries

    NASA Astrophysics Data System (ADS)

    Mohamed, S.; Booth, R.; Podsiadlowski, Ph.; Ramstedt, S.; Vlemmings, W.; Maercker, M.

    2015-12-01

    Symbiotic binaries consist of a cool, mass-losing giant and an accreting, compact companion. We present 3D Smoothed Particle Hydrodynamics (SPH) models of two such interacting binaries, RS Oph and Mira AB. RS Oph is also a recurrent nova system, thus we model multiple quiescent mass transfer-nova outburst cycles. The resulting circumstellar structures of both systems are highly complex with the formation of spirals, arcs, shells, equatorial and bipolar outflows. We compare the models to recent observations and discuss the implications of our results for related systems, e.g., bipolar nebulae and jets, chemically peculiar stars, and the progenitors of Type Ia supernovae.

  18. NSLS RF system improvements

    SciTech Connect

    Keane, J.; Thomas, M.; McKenzie-Wilson, R.; D'Alsace, R.; Ackerman, H.; Biscardi, R.; Langenbach, H.; Ramirez, G.

    1985-01-01

    It is required that the NSLS x-ray accelerator reach an energy of 2.5 GeV. An additional accelerating cavity and power amplifier system were installed to meet this goal. A new control system was designed to include phase and amplitude servos as well as computer interfacing. Commissioning and operating experience will be reported.

  19. Spectral and timing nature of the symbiotic X-ray binary 4U 1954+319: The slowest rotating neutron star in an X-ray binary system

    SciTech Connect

    Enoto, Teruaki; Corbet, Robin H. D.; Sasano, Makoto; Yamada, Shin'ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Fuerst, Felix; Wilms, Jörn

    2014-05-10

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its ∼5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (∼7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-Kα line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (∼60%-80%), and the location in the Corbet diagram favor high B-field (≳ 10{sup 12} G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10{sup 33}-10{sup 35} erg s{sup –1}), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a ∼10{sup 13} G NS, this scheme can explain the ∼5.4 hr equilibrium rotation without employing the magnetar-like field (∼10{sup 16} G) required in the disk accretion case. The timescales of multiple irregular flares (∼50 s) can also be attributed to the free-fall time from the Alfvén shell for a ∼10{sup 13} G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  20. Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

    NASA Technical Reports Server (NTRS)

    Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

    2014-01-01

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  1. Fire alarm system improvement

    SciTech Connect

    Hodge, S.G.

    1994-10-01

    This document contains the Fire Alarm System Test Procedure for Building 234-5Z, 200-West Area on the Hanford Reservation, Richland, Washington. This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the modifications to the Fire Protection systems function as required by project criteria. The ATP will test the Fire Alarm Control Panels, Flow Alarm Pressure Switch, Heat Detectors, Smoke Detectors, Flow Switches, Manual Pull Stations, and Gong/Door by Pass Switches.

  2. Analysis of the symbiotic star AG Pegasi

    NASA Technical Reports Server (NTRS)

    Keyes, C. D.; Plavec, M. J.

    1981-01-01

    High and low dispersion IUE data are analyzed in conjunction with coincident ground based spectrophotometric scans and supplementary infrared photometry of the symbiotic object AG Pegasi. The IUE observations yield an improved value of E(B-V) = 0.12. The two stellar components are easily recognized in the spectra. The cool component may be an M1.7 III star and the hot component appears to have T (sub eff) of approximately 30000 K. The emission lines observed in the ultraviolet indicate two or three distince emitting regions. Nebular component ultraviolet intercombination lines suggest an electron density of several times 10 billion/cu cm.

  3. Improved cryogenic refrigeration system

    NASA Technical Reports Server (NTRS)

    Higa, W. H.

    1967-01-01

    Two-position shuttle valve simplifies valving arrangement and crank-shaft configuration in gas-balancing and Stirling-cycle refrigeration systems used to produce temperatures below 173 degrees K. It connects the displacer and regenerator alternately to the supply line or the return line of the compressor, and establishes constant pressure on the drive piston.

  4. Improved docking alignment system

    NASA Technical Reports Server (NTRS)

    Monford, Leo G. (Inventor)

    1988-01-01

    Improved techniques are provided for the alignment of two objects. The present invention is particularly suited for 3-D translation and 3-D rotational alignment of objects in outer space. A camera is affixed to one object, such as a remote manipulator arm of the spacecraft, while the planar reflective surface is affixed to the other object, such as a grapple fixture. A monitor displays in real-time images from the camera such that the monitor displays both the reflected image of the camera and visible marking on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

  5. [Significance of hydrobiont persistent properties for symbiotic interactions].

    PubMed

    Nemtseva, N V

    2012-01-01

    Significance of symbiotic relations formed by associative symbiosis type for autochthonous and allochthonous microflora of natural water bodies is shown. Generality of symbiotic interaction mechanisms of symbionts in limnetic and halophilous communities provided by secreted factors of natural resistance from the side of the host, and by factors of persistence from the side of symbionts is proven based on a set of examples. Features of operation of lysozyme-antilysozyme, histon-antihiston, hydrogen peroxide-catalase functional systems in symbiotic interactions of autotrophic and heterotrophic components of hydrobiocenosis with dominant and associative microflora are presented. Associative microflora of allochthonous origin was shown to actively use the ecologically formed system of interaction between hydrobionts that facilitates survival of these microorganisms and preservation of their persistent potential, and as a result leads to biocenosis disorders. The knowledge obtained open new possibilities and perspectives of research of sanitary and ecological aspects of vital activity of aquatic biocenoses. PMID:22937711

  6. Carbon budgets in symbiotic associations

    SciTech Connect

    Muscatine, L.; Falkowski, P.G.; Dubinsky, Z.

    1983-01-01

    Methods are described which permit the estimation of daily budgets for photosynthetically fixed carbon in any alga-invertebrate symbiosis. Included is a method for estimating total daily translocation which does not involve the use of C-14. A daily carbon budget for a shallow water symbiotic reef coral is presented.

  7. OIT geothermal system improvements

    SciTech Connect

    Lienau, P.J.

    1996-08-01

    Three geothermal wells drilled during the original campus construction vary from 396 m (1,300 ft) to 550 m (1,800 ft). These wells supply all of the heating and part of the cooling needs of the 11-building, 62,200 m{sup 2} (670,000 ft{sup 2}) campus. The combined capacity of the well pumps is 62 L/s(980 gpm) of 89{degrees}C (192{degrees}F) geothermal fluids. Swimming pool and domestic hot water heating impose a small but nearly constant year-round flow requirement. In addition to heating, a portion of the campus is also cooled using the geothermal resource. This is accomplished through the use of an absorption chiller. The chiller, which operates on the same principle as a gas refrigerator, requires a flow of 38 L/s (600 gpm) of geothermal fluid and produces 541 kW (154 tons) of cooling capacity (Rafferty, 1989). The annual operating costs for the system is about $35,000 including maintenance salary, equipment replacement and cost of pumping. This amounts to about $0.05 per square foot per year.

  8. Discussion on selected symbiotic stars

    NASA Technical Reports Server (NTRS)

    Viotti, Roberto; Hack, Margherita

    1993-01-01

    Because of its large variety of aspects, the symbiotic phenomenon is not very suitable for a statistical treatment. It is also not clear whether symbiotic stars really represent a homogeneous group of astrophysical objects or a collection of objects of different natures but showing similar phenomena. However we are especially interested in the symbiotic phenomenon, i.e., in those physical processes occurring in the atmosphere of each individual object and in their time dependence. Such a research can be performed through the detailed analysis of individual objects. This study should be done for a time long enough to cover all the different phases of their activity, in all the spectral ranges. Since the typical time scale of the symbiotic phenomena is up to several years and decades, this represents a problem since, for instance, making astronomy outside the visual region is a quite new field of research. It was a fortunate case that a few symbiotic stars (Z And, AG Dra, CH Cyg, AX Per, and PU Vul) had undergone remarkable light variations (or 'outbursts') in recent years, which could have been followed in the space ultraviolet with IUE, and simultaneously in the optical and IR with ground-based telescopes. But, in general, the time coverage of most of the symbiotic objects is too short to have a complete picture of their behavior. In this regard, one should recall Mayall's remark about the light curve of Z And: 'Z Andromedae is another variable that shows it will require several hundred years of observations before a good analysis can be made of its variations'. This pessimistic remark should be considered as a note of caution for those involved in the interpretation of the observations. We shall discuss a number of individual symbiotic stars for which the amount of observational data is large enough to draw a rather complete picture of their general behavior and to make consistent models. We shall especially illustrate the necessary steps toward an empirical model

  9. The effect of symbiotic ant colonies on plant growth: a test using an Azteca-Cecropia system.

    PubMed

    Oliveira, Karla N; Coley, Phyllis D; Kursar, Thomas A; Kaminski, Lucas A; Moreira, Marcelo Z; Campos, Ricardo I

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ(15)N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ(15)N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change. PMID:25811369

  10. The Effect of Symbiotic Ant Colonies on Plant Growth: A Test Using an Azteca-Cecropia System

    PubMed Central

    Oliveira, Karla N.; Coley, Phyllis D.; Kursar, Thomas A.; Kaminski, Lucas A.; Moreira, Marcelo Z.; Campos, Ricardo I.

    2015-01-01

    In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ15N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change. PMID:25811369

  11. Improving an Imperfect Metric System

    ERIC Educational Resources Information Center

    Frasier, E. Lewis

    1974-01-01

    Suggests some improvements and additional units necessary for the International Metric System to expand its use to all measureable entities and defined quantities, especially in the measurement of time and angles. Included are tables of proposed unit systems in contrast with the presently available systems. (CC)

  12. Outbursts In Symbiotic Binaries (FUSE 2000)

    NASA Technical Reports Server (NTRS)

    Kenyon, Scott J.; Sonneborn, George (Technical Monitor)

    2002-01-01

    with line variations - will yield physical parameters for the expanding shell of gas in the outer atmosphere of the hot component. We also worked on several diagnostic tools, including upgrades to photoionization programs developed by the PI and others. We plan to use these tools to derive electron densities and temperatures front intercombination and forbidden lines observed on optical and FUSE spectra. Preliminary results indicate a large electron density, n(sub e) is greater than or = 10(exp 10)/cc and a modest electron temperature, T(sub e) approx. 20,000 K. We see no evidence for shocked gas as observed in some other symbiotics. However, we have yet to include several important lines of [Fe VII] and [Ne V] in the analysis. Inclusion of these lines will yield an improved estimate of the electron temperature in the gas. Finally, we have one additional FUSE spectrum planned for acquisition during this cycle. These data will provide important information concerning the state of the system farther along in its decline. Once we have this spectrum in hand, we plan to complete our analysis and publish our results.

  13. Formation of broad Balmer wings in symbiotic stars

    NASA Astrophysics Data System (ADS)

    Chang, Seok-Jun; Heo, Jeong-Eun; Hong, Chae-Lin; Lee, Hee-Won

    2016-07-01

    Symbiotic stars are binary systems composed of a hot white dwarf and a mass losing giant. In addition to many prominent emission lines symbiotic stars exhibit Raman scattered O VI features at 6825 and 7088 Å. Another notable feature present in the spectra of many symbiotics is the broad wings around Balmer lines. Astrophysical mechanisms that can produce broad wings include Thomson scattering by free electrons and Raman scattering of Ly,β and higher series by neutral hydrogen. In this poster presentation we produce broad wings around Hα and H,β adopting a Monte Carlo techinique in order to make a quantitative comparison of these two mechanisms. Thomson wings are characterized by the exponential cutoff given by the termal width whereas the Raman wings are dependent on the column density and continuum shape in the far UV region. A brief discussion is provided.

  14. Innate immunity underlies symbiotic relationships.

    PubMed

    Kisseleva, E P

    2014-12-01

    Here, the modern data regarding interactions between normal microbiota and barrier tissues in plants, humans and animals are reviewed. The main homeostatic mechanisms responsible for interactions between epithelium and innate immune cells with symbiotic bacteria are described. A key step in this process is recognition of soluble microbial products by ligation to pattern-recognition receptors expressed on the host cells. As a result, epithelial cells secrete mucus, antibacterial peptides and immunoregulatory molecules. The main outcomes from immunological reactions towards symbiotic bacteria involve development of conditions for formation and maintenance of microbial biocenosis as well as providing safety for the host. Also, it is considered important to preserve and transfer beneficial bacteria to progeny. PMID:25716721

  15. Innoculation of Almond Rootstock with Symbiotic Arbuscular Mycorrhizal Fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil borne arbuscular mycorrhizal (AM) fungus forms a symbiotic (mutualistic) relationship with most plants. The fungus colonizes the root and grows out into the soil. Hyphae net work, the part of the fungus that's in the soil acts as an extension of the root system. The scope of the research is to ...

  16. V479 And: CV, LMXB, or Symbiotic?

    NASA Astrophysics Data System (ADS)

    Buitrago, Diego González; Tovmassian, Gagik; Echevarría, Juan; Zharikov, Sergey; Miyaji, Takamitsu; Avilés, Andres; Valyavin, Gennady

    2013-01-01

    V479 And is a 14.26 hour, close binary system, comprised of a G8-K0 star departing from the main sequence and a compact primary star accreting matter from the donor. The object is an X-ray source, modulated with the orbital period. This, and the presence of an intense He II line, leads us to speculate that the compact object is a magnetic white dwarf. However, we do not find strong constraints on the upper mass limit of the compact object, and we may have a neutron star in a low mass X-ray binary instead of a cataclysmic variable. The orbital period is certainly too short for the donor star to be an evolved giant star, so classifying this object as a symbiotic binary may be a big stretch; however there is an evidence that the mass transfer occurs via stellar winds, rather than through the L1 point of Roche filling secondary, a phenomenon more common for symbiotic stars.

  17. Monogamy in a Hyper-Symbiotic Shrimp.

    PubMed

    Baeza, J Antonio; Simpson, Lunden; Ambrosio, Louis J; Guéron, Rodrigo; Mora, Nathalia

    2016-01-01

    Theory predicts that monogamy is adaptive in resource-specialist symbiotic crustaceans inhabiting relatively small and morphologically simple hosts in tropical environments where predation risk away from hosts is high. We tested this prediction in Pontonia manningi, a hyper-symbiotic shrimp that dwells in the mantle cavity of the Atlantic winged oyster Pteria colymbus that, in turn, infects gorgonians from the genus Pseudopterogorgia in the Caribbean Sea. In agreement with theory, P. manningi were found dwelling as heterosexual pairs in oysters more frequently than expected by chance alone. Males and females also inhabited the same host individual independent of the female gravid condition or of the developmental stage of brooded embryos. While the observations above argue in favor of monogamy in P. manningi, there is evidence to suggest that males of the studied species are moderately promiscuous. That females found living solitary in oysters most often brooded embryos, and that males allocated more to weaponry (major claw size) than females at any given size suggest that males might be roaming among host individuals in search of and, fighting for, receptive females. All available information depicts a rather complex mating system in P. manningi: primarily monogamous but with moderately promiscuous males. PMID:26934109

  18. Monogamy in a Hyper-Symbiotic Shrimp

    PubMed Central

    Baeza, J. Antonio; Simpson, Lunden; Ambrosio, Louis J.; Guéron, Rodrigo; Mora, Nathalia

    2016-01-01

    Theory predicts that monogamy is adaptive in resource-specialist symbiotic crustaceans inhabiting relatively small and morphologically simple hosts in tropical environments where predation risk away from hosts is high. We tested this prediction in Pontonia manningi, a hyper-symbiotic shrimp that dwells in the mantle cavity of the Atlantic winged oyster Pteria colymbus that, in turn, infects gorgonians from the genus Pseudopterogorgia in the Caribbean Sea. In agreement with theory, P. manningi were found dwelling as heterosexual pairs in oysters more frequently than expected by chance alone. Males and females also inhabited the same host individual independent of the female gravid condition or of the developmental stage of brooded embryos. While the observations above argue in favor of monogamy in P. manningi, there is evidence to suggest that males of the studied species are moderately promiscuous. That females found living solitary in oysters most often brooded embryos, and that males allocated more to weaponry (major claw size) than females at any given size suggest that males might be roaming among host individuals in search of and, fighting for, receptive females. All available information depicts a rather complex mating system in P. manningi: primarily monogamous but with moderately promiscuous males. PMID:26934109

  19. Leading System-Wide Improvement

    ERIC Educational Resources Information Center

    Harris, Alma

    2012-01-01

    Around the world there is a preoccupation with improving the performance of schools and school systems. Comparisons made between countries through PISA and PERLs have led to a preoccupation, and in some cases, an obsession, with securing a high position in the international league tables. The minds of policy-makers and politicians alike are…

  20. Ozone measurement systems improvements studies

    NASA Technical Reports Server (NTRS)

    Thomas, R. W.; Guard, K.; Holland, A. C.; Spurling, J. F.

    1974-01-01

    Results are summarized of an initial study of techniques for measuring atmospheric ozone, carried out as the first phase of a program to improve ozone measurement techniques. The study concentrated on two measurement systems, the electro chemical cell (ECC) ozonesonde and the Dobson ozone spectrophotometer, and consisted of two tasks. The first task consisted of error modeling and system error analysis of the two measurement systems. Under the second task a Monte-Carlo model of the Dobson ozone measurement technique was developed and programmed for computer operation.

  1. Molecular and biochemical analysis of symbiotic plant receptor kinase complexes

    SciTech Connect

    Cook, Douglas R; Riely, Brendan K

    2010-09-01

    DE-FG02-01ER15200 was a 36-month project, initiated on Sept 1, 2005 and extended with a one-year no cost extension to August 31, 2009. During the project period we published seven manuscripts (2 in review). Including the prior project period (2002-2005) we published 12 manuscripts in journals that include Science, PNAS, The Plant Cell, Plant Journal, Plant Physiology, and MPMI. The primary focus of this work was to further elucidate the function of the Nod factor signaling pathway that is involved in initiation of the legume-rhizobium symbiosis and in particular to explore the relationship between receptor kinase-like proteins and downstream effectors of symbiotic development. During the project period we have map-base cloned two additional players in symbiotic development, including an ERF transcription factor and an ethylene pathway gene (EIN2) that negatively regulates symbiotic signaling; we have also further characterized the subcellular distribution and function of a nuclear-localized symbiosis-specific ion channel, DMI1. The major outcome of the work has been the development of systems for exploring and validating protein-protein interactions that connect symbiotic receptor-like proteins to downstream responses. In this regard, we have developed both homologous (i.e., in planta) and heterologous (i.e., in yeast) systems to test protein interactions. Using yeast 2-hybrid screens we isolated the only known interactor of the nuclear-localized calcium-responsive kinase DMI3. We have also used yeast 2-hybrid methodology to identify interactions between symbiotic signaling proteins and certain RopGTPase/RopGEF proteins that regulate root hair polar growth. More important to the long-term goals of our work, we have established a TAP tagging system that identifies in planta interactions based on co-immuno precipitation and mass spectrometry. The validity of this approach has been shown using known interactors that either co-iummnoprecipate (i.e., remorin) or co

  2. Discovery of true, likely and possible symbiotic stars in the dwarf spheroidal NGC 205

    NASA Astrophysics Data System (ADS)

    Gonçalves, Denise R.; Magrini, Laura; de la Rosa, Ignacio G.; Akras, Stavros

    2015-02-01

    In this paper we discuss the photometric and spectroscopic observations of newly discovered (symbiotic) systems in the dwarf spheroidal galaxy NGC 205. The Gemini Multi-Object Spectrograph on-off band [O III] 5007 Å emission imaging highlighted several [O III] line emitters, for which optical spectra were then obtained. The detailed study of the spectra of three objects allows us to identify them as true, likely and possible symbiotic systems (SySts), the first ones discovered in this galaxy. SySt-1 is unambiguously classified as a symbiotic star, because of the presence of unique emission lines which belong only to symbiotic spectra, the well-known O VI Raman-scattered lines. SySt-2 is only possibly a SySt because the Ne VII Raman-scattered line at 4881 Å, recently identified in a well-studied Galactic symbiotic as another very conspicuous property of symbiotic, could as well be identified as N III or [Fe III]. Finally, SySt-3 is likely a symbiotic binary because in the red part of the spectrum it shows the continuum of a late giant, and forbidden lines of moderate to high ionization, like [Fe V] 4180 Å. The main source for scepticism on the symbiotic nature of the latter systems is their location in the planetary nebula region in the [O III]4363/Hγ versus [O III]5007/Hβ diagnostic diagram. It is worth mentioning that at least another two confirmed symbiotics, one of the Local Group dwarf spheroidal IC 10 and the other of the Galaxy, are also misplaced in this diagram.

  3. Optical Variability of X-Ray Bright Southern Symbiotic Stars

    NASA Astrophysics Data System (ADS)

    Hedrick, C.; Sokoloski, J.

    2004-12-01

    We performed weekly B- and V-band observations of four X-ray bright southern symbiotic binary stars -- CD-43 14304, Hen 3-1591, LMC S63, and SMC LN 358 -- using the 1.3-m telescope at Cerro Tololo Inter-American Observatory (CTIO). We began optical monitoring in August 2003 for two of the objects (LMC S63 and SMC LN 358) and in January 2004 for the other two objects (CD-43 14304 and Hen 3-1591). None of the four survey objects experienced a major outburst during the monitoring period. We did, however, detect small-amplitude ( 0.1 mag) optical variability on a time scale of tens of days, for the first time, in each of the four systems. Both the structure and amplitude of the variations are roughly the same in the B band and V band in all of the symbiotics in our sample except one (LMC S63), and is most consistent with the idea that the week-time-scale variability originates with the hot component (most likely an accreting white dwarf) rather than the red giant. We compare the variability properties of our small sample of X-ray-bright symbiotic stars to those of samples of both X-ray-bright and X-ray-dim symbiotic stars from the database of the American Association of Variable Star Observers (AAVSO).

  4. Characteristics of the hot components of symbiotic stars

    NASA Astrophysics Data System (ADS)

    Burmeister, Mari

    2010-08-01

    Symbiotic stars are interacting binaries whose components are a red giant and a small hot star, usually a white dwarf. The intensive stellar wind from the giant is captured by the companion, giving rise to strong emission lines in the spectra and a range of phenomena, which may include the formation of an accretion disk and the ejection of collimated jets. In this thesis, four symbiotic stars, as different as possible, were chosen for a spectral investigation of the symbiotic phenomenon. Of those, Z Andromedae is a so-called classical symbiotic star with a hot companion that shows a characteristic pattern of brightenings (outbursts). AG Draconis is a bright system like Z Andromedae and shows similar activity, but has an unusually hot yellow donor star. CH Cygni and EG Andromedae have, on the contrary, relatively dim white dwarfs. The former shows irregular outbursts, the origin of which is not easy to explain, the latter is one of the quiet symbiotic stars with no outburst yet recorded. Each of those four stars was observed for at least ten years with the 1.5-m telescope at Tartu Observatory. Several outbursts of Z Andromedae and AG Draconis were witnessed, as well as substantial changes in the CH Cygni spectra. The perhaps most surprising result was the discovery of collimated jets in Z Andromedae spectra on two instances, an event never observed in this star before. In CH Cygni, evidence for the existence of an accretion disk in 1998 was discovered. EG Andromedae stayed quiet and the only changes in its spectra could be ascribed to orbital motion. We found that not all the outbursts of Z Andromedae and AG Draconis are accompanied by similar changes in the spectra: during some brightenings the stars become hotter, during some, cooler. The existence of the disk in CH Cygni in 1998 affirms that the formation of such a structure is possible in symbiotic stars. Moreover, as the ejection of jets is associated to an accretion disk, the jets in Z Andromedae can also be

  5. Molecular Basis of Symbiotic Promiscuity

    PubMed Central

    Perret, Xavier; Staehelin, Christian; Broughton, William J.

    2000-01-01

    Eukaryotes often form symbioses with microorganisms. Among these, associations between plants and nitrogen-fixing bacteria are responsible for the nitrogen input into various ecological niches. Plants of many different families have evolved the capacity to develop root or stem nodules with diverse genera of soil bacteria. Of these, symbioses between legumes and rhizobia (Azorhizobium, Bradyrhizobium, Mesorhizobium, and Rhizobium) are the most important from an agricultural perspective. Nitrogen-fixing nodules arise when symbiotic rhizobia penetrate their hosts in a strictly controlled and coordinated manner. Molecular codes are exchanged between the symbionts in the rhizosphere to select compatible rhizobia from pathogens. Entry into the plant is restricted to bacteria that have the “keys” to a succession of legume “doors”. Some symbionts intimately associate with many different partners (and are thus promiscuous), while others are more selective and have a narrow host range. For historical reasons, narrow host range has been more intensively investigated than promiscuity. In our view, this has given a false impression of specificity in legume-Rhizobium associations. Rather, we suggest that restricted host ranges are limited to specific niches and represent specialization of widespread and more ancestral promiscuous symbioses. Here we analyze the molecular mechanisms governing symbiotic promiscuity in rhizobia and show that it is controlled by a number of molecular keys. PMID:10704479

  6. Symbiotic stars in X-rays and UV

    NASA Astrophysics Data System (ADS)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.; Nuñez, N. E.

    2014-10-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. I will describe the detection with the Swift/XRT of 14 white dwarf symbiotics that were not previously known to be X-ray sources. The 14 new X-ray detections were the result of a survey of more than 50 symbiotic stars using Swift fill-in programs during three years. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. Simultaneous Swift/UVOT data allowed us to find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, the UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk.

  7. An improved criticality alarm system

    SciTech Connect

    Tyree, W.H.; Gilpin, H.E.; Balmer, D.K.; Vennitti, D.A.

    1991-12-31

    The Rocky Flats Plant near Golden, Colorado is the primary facility for the production of plutonium components used in the US arsenal of nuclear weapons. It is operated by EG&G under contract to the US Department of Energy (DOE). There are ten production buildings on plant site with neutron based criticality alarm systems. These systems have been in operation for the past seventeen years. Changes in the interpretation of A.N.S.I. standards and DOE orders have precipitated an evaluation of detector sensitivity and placement criteria. As a result of this evaluation, improvements in detector design and calibration have improved detector sensitivity by a factor of six. Testing performed on the design defined a minimum sensitivity as required by A.N.S.I. 8.3 and provided information for saturation and survivability for a fission event of up to 1 {times} 10{sup 17} fissions in 80 microseconds. A rigorous testing and calibration program has been developed and is in place. Neutron sensitivity is certified at a nearby reactor which is traceable to N.I.S.T.. 4 refs.

  8. IUE observations of symbiotic stars

    NASA Technical Reports Server (NTRS)

    Hack, M.

    1982-01-01

    The main photometric and spectroscopic characteristics in the ultraviolet and visual range of the most extensively studied symbiotic stars are reviewed. The main data obtained with IUE concern: (1) the determination of the shape of the UV continuum, which, in some cases, proves without doubt the presence of a hot companion; and the determination of the interstellar extinction by means of the lambda 2200 feature; (2) the measurement of emission lines, which enables us to derive the electron temperature and density of the circumstellar envelope, and, taken together with those lines observed in the visual, give more complete information on which spectroscopic mechanisms operate in the envelope; (3) the observation of absorption lines in the UV, which are present in just a few cases.

  9. Circumstellar Dust in Symbiotic Novae

    NASA Astrophysics Data System (ADS)

    Jurkic, T.; Kotnik-Karuza, D.

    2015-12-01

    We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the near-IR photometry, ISO spectra and mid-IR interferometry. The dust properties were determined using the DUSTY code. A compact circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel shows the presence of an equatorially enhanced dust density during minimum obscuration. Obscuration events are explained by an increase in optical depth caused by the newly condensed dust. The mass loss rates are significantly higher than in intermediate-period single Miras but in agreement with longer-period O-rich AGB stars.

  10. Ultraviolet properties of the symbiotic stars

    NASA Technical Reports Server (NTRS)

    Slovak, M. H.; Lambert, D. L.

    1982-01-01

    A general discussion of the UV spectra of symbiotic stars, including both the emission lines and the continua, is presented, with AG Pegasi considered as an illustrative example. It is noted that the IUE observations of the symbiotics have revealed UV properties which rival the diversity of the optical features. Nevertheless, the UV data have for the first time permitted the hot component to be studied relatively uncontaminated by the giant companion, which dominates the optical regime. The UV observations provide convincing evidence that many of the symbiotics have hot stellar companions embedded in the enshrouding nebula or accretion shell formed from the wind from one or possibly both of the components.

  11. TIDALLY ENHANCED STELLAR WIND: A WAY TO MAKE THE SYMBIOTIC CHANNEL TO TYPE Ia SUPERNOVA VIABLE

    SciTech Connect

    Chen, X.; Han, Z.

    2011-07-10

    In the symbiotic (or WD+RG) channel of the single-degenerate scenario for type Ia supernovae (SNe Ia), the explosions occur a relatively long time after star formation. The birthrate from this channel would be too low to account for all observed SNe Ia were it not for some mechanism to enhance the rate of accretion on to the white dwarf. A tidally enhanced stellar wind, of the type which has been postulated to explain many phenomena related to giant star evolution in binary systems, can do this. Compared to mass stripping, this model extends the space of SNe Ia progenitors to longer orbital periods and hence increases the birthrate to about 0.0069 yr{sup -1} for the symbiotic channel. Two symbiotic stars, T CrB and RS Oph, considered to be the most likely progenitors of SNe Ia through the symbiotic channel, are well inside the period-companion mass space predicted by our models.

  12. INFRARED SPECTROSCOPY OF SYMBIOTIC STARS. IX. D-TYPE SYMBIOTIC NOVAE

    SciTech Connect

    Hinkle, Kenneth H.; Joyce, Richard R.; Fekel, Francis C.; Wood, Peter E-mail: joyce@noao.edu E-mail: wood@mso.anu.edu.au

    2013-06-10

    Time-series spectra of the near-infrared 1.6 {mu}m region have been obtained for five of the six known D-type symbiotic novae. The spectra map the pulsation kinematics of the Mira component in the Mira-white dwarf binary system and provide the center-of-mass velocity for the Mira. No orbital motion is detected in agreement with previous estimates of orbital periods {approx}>100 yr and semimajor axes {approx}50 AU. The 1-5 {mu}m spectra of the Miras show line weakening during dust obscuration events. This results from scattering and continuum emission by 1000 K dust. In the heavily obscured HM Sge system the 4.6 {mu}m CO spectrum formed in 1000 K gas is seen in emission against an optically thick dust continuum. Spectral features that are typically produced in either the cool molecular region or the expanding circumstellar region of late-type stars cannot be detected in the D-symbiotic novae. This is in accord with the colliding wind model for interaction between the white dwarf and Mira. Arguments are presented that the 1000 K gas and dust are not Mira circumstellar material but are in the wind interaction region of the colliding winds. CO is the first molecule detected in this region. We suggest that dust condensing in the intershock region is the origin of the dust obscuration. This model explains variations in the obscuration. Toward the highly obscured Mira in HM Sge the dust zone is estimated to be {approx}0.1 AU thick. The intershock wind interaction zone appears thinnest in the most active systems. Drawing on multiple arguments masses are estimated for the system components. The Miras in most D-symbiotic novae have descended from intermediate mass progenitors. The large amount of mass lost from the Mira combined with the massive white dwarf companion suggests that these systems are supernova candidates. However, timescales and the number of objects make these rare events.

  13. Symbiotic control of mosquito borne disease.

    PubMed

    Ricci, Irene; Valzano, Matteo; Ulissi, Ulisse; Epis, Sara; Cappelli, Alessia; Favia, Guido

    2012-11-01

    It is well accepted that the symbiotic relationships insects have established with several microorganisms have had a key role in their evolutionary success. Bacterial symbiosis is also prevalent in insects that are efficient disease vectors, and numerous studies have sought to decrypt the basic mechanisms of the host-symbiont relationships and develop ways to control vector borne diseases. 'Symbiotic control', a new multifaceted approach that uses symbiotic microorganisms to control insect pests or reduce vector competence, seems particularly promising. Three such approaches currently at the cutting edge are: (1) the disruption of microbial symbionts required by insect pests; (2) the manipulation of symbionts that can express anti-pathogen molecules within the host; and (3) the introduction of endogenous microbes that affect life-span and vector capacity of the new hosts in insect populations. This work reviews current knowledge on microbial symbiosis in mosquitoes that holds promise for development of symbiotic control for mosquito borne diseases. PMID:23265608

  14. The Bright Symbiotic Mira EF Aquilae

    NASA Astrophysics Data System (ADS)

    Margon, Bruce; Prochaska, J. Xavier; Tejos, Nicolas; Monroe, TalaWanda

    2016-02-01

    An incidental spectrum of the poorly studied long-period variable EF Aquilae shows [O III] emission indicative of a symbiotic star. Strong GALEX detections in the UV reinforce this classification, providing overt evidence for the presence of the hot subluminous companion. Recent compilations of the photometric behavior strongly suggest that the cool component is a Mira variable. Thus EF Aql appears to be a member of the rare symbiotic Mira subgroup.

  15. Obtaining hemocytes from the Hawaiian bobtail squid Euprymna scolopes and observing their adherence to symbiotic and non-symbiotic bacteria.

    PubMed

    Collins, Andrew J; Nyholm, Spencer V

    2010-01-01

    Studies concerning the role of the immune system in mediating molecular signaling between beneficial bacteria and their hosts have, in recent years, made significant contributions to our understanding of the co-evolution of eukaryotes with their microbiota. The symbiotic association between the Hawaiian bobtail squid, Euprymna scolopes and the bioluminescent bacterium Vibrio fischeri has been utilized as a model system for understanding the effects of beneficial bacteria on animal development. Recent studies have shown that macrophage-like hemocytes, the sole cellular component of the squid host's innate immune system, likely play an important role in mediating the establishment and maintenance of this association. This protocol will demonstrate how to obtain hemocytes from E. scolopes and then use these cells in bacterial binding assays. Adult squid are first anesthetized before hemolymph is collected by syringe from the main cephalic blood vessel. The host hemocytes, contained in the extracted hemolymph, are adhered to chambered glass coverslips and then exposed to green fluorescent protein-labeled symbiotic Vibrio fischeri and non-symbiotic Vibrio harveyi. The hemocytes are counterstained with a fluorescent dye (Cell Tracker Orange, Invitrogen) and then visualized using fluorescent microscopy. PMID:20150890

  16. Circumstellar dust in symbiotic novae

    NASA Astrophysics Data System (ADS)

    Jurkic, Tomislav; Kotnik-Karuza, Dubravka

    2015-08-01

    Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding evolution of symbiotic binaries. We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the long-term near-IR photometry, infrared ISO spectra and mid-IR interferometry. Pulsation properties and long-term variabilities were found from the near-IR light curves. The dust properties were determined using the DUSTY code which solves the radiative transfer. No changes in pulsational parameters were found, but a long-term variations with periods of 20-25 years have been detected which cannot be attributed to orbital motion.Circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel showed the presence of an optically thin CS dust envelope and an optically thick dust region outside the line of sight, which was further supported by the detailed modelling using the 2D LELUYA code. Obscuration events in RR Tel were explained by an increase in optical depth caused by the newly condensed dust leading to the formation of a compact dust shell. HM Sge showed permanent obscuration and a presence of a compact dust shell with a variable optical depth. Scattering of the near-IR colours can be understood by a change in sublimation temperature caused by the Mira variability. Presence of large dust grains (up to 4 µm) suggests an increased grain growth in conditions of increased mass loss. The mass loss rates of up to 17·10-6 MSun/yr were significantly higher than in intermediate-period single Miras and in agreement with longer-period O-rich AGB stars.Despite the nova outburst, HM Sge remained enshrouded in dust with no significant dust destruction. The existence of unperturbed dust shell suggests a small influence of the hot component and strong dust shielding from the UV flux. By the use

  17. Symbiotic structures to significantly enhance space missions

    NASA Astrophysics Data System (ADS)

    Williams, Andrew D.; Diaz-Aguado, Millan; Arritt, Brandon J.

    2007-04-01

    The Department of Defense is actively pursuing a Responsive Space capability that will dramatically reduce the cost and time associated with getting a payload into space. In order to enable that capability, our space systems must be modular and flexible to cover a wide range of missions, configurations, duty cycles, and orbits. This places requirements on the entire satellite infrastructure: payloads, avionics, electrical harnessing, structure, thermal management system, etc. The Integrated Structural Systems Team at the Air Force Research Laboratory, Space Vehicles Directorate, has been tasked with developing structural and thermal solutions that will enable a Responsive Space capability. This paper details a "symbiotic" solution where thermal management functionality is embedded within the structure of the satellite. This approach is based on the flight proven and structurally efficient isogrid architecture. In our rendition, the ribs serve as fluidic passages for thermal management, and passively activated valves are used to control flow to the individual components. As the paper will explain, our analysis has shown this design to be structurally efficient and thermally responsive to a wide range of potential satellite missions, payloads, configurations, and orbits.

  18. The Frankia alni symbiotic transcriptome.

    PubMed

    Alloisio, Nicole; Queiroux, Clothilde; Fournier, Pascale; Pujic, Petar; Normand, Philippe; Vallenet, David; Médigue, Claudine; Yamaura, Masatoshi; Kakoi, Kentaro; Kucho, Ken-ichi

    2010-05-01

    The actinobacteria Frankia spp. are able to induce the formation of nodules on the roots of a large spectrum of actinorhizal plants, where they convert dinitrogen to ammonia in exchange for plant photosynthates. In the present study, transcriptional analyses were performed on nitrogen-replete free-living Frankia alni cells and on Alnus glutinosa nodule bacteria, using whole-genome microarrays. Distribution of nodule-induced genes on the genome was found to be mostly over regions with high synteny between three Frankia spp. genomes, while nodule-repressed genes, which were mostly hypothetical and not conserved, were spread around the genome. Genes known to be related to nitrogen fixation were highly induced, nif (nitrogenase), hup2 (hydrogenase uptake), suf (sulfur-iron cluster), and shc (hopanoids synthesis). The expression of genes involved in ammonium assimilation and transport was strongly modified, suggesting that bacteria ammonium assimilation was limited. Genes involved in particular in transcriptional regulation, signaling processes, protein drug export, protein secretion, lipopolysaccharide, and peptidoglycan biosynthesis that may play a role in symbiosis were also identified. We also showed that this Frankia symbiotic transcriptome was highly similar among phylogenetically distant plant families Betulaceae and Myricaceae. Finally, comparison with rhizobia transcriptome suggested that F. alni is metabolically more active in symbiosis than rhizobia. PMID:20367468

  19. [A psychotic symbiotic child. Clinical and psychopathological study].

    PubMed

    Ledoux, M H

    1993-01-01

    Through the case study of a psychotic girl, we have tried to outline the psychotic mechanisms involved in this mental functioning. Anxieties of an autistic type have been found, as well as anxieties of a more psychotic type (i.e. symbiotic and schizophrenic). Characteristics of this psychotic functioning were: omnipotence, primitive identification mechanisms, fragmenting separation anxiety, search for sameness and for a low of identical repetition, difficulties in accessing to symbolism. Difficulties in defusion from the symbiotic object and the potential role played by this object in the difficulties are noteworthy. But it is not possible to conceptualize them in terms of direct causal relationship, because the object has also a counterphobic function and compensates for the void of subject as well as for the dissolution of the self. Also present is a schizoparanoïd aspect, with a temptation to cuddle inside the object. The sudden breaking through of informations or requirements from reality provokes surprise, panic reactions and retirement from the objectal world. Otherness triggers psychic pain and vacillation of symbiotic bounds. Thus the avoidance of, and retirement from, reality and the recourse to delusional thinking, especially when attempts to controlling with a rigid system are failing and deceiving. Threats of intrusion and loss of control are experienced as a threat of fragmentation and dissolution of the psyche. Far less threatening to the subject's internal balance is the policy of rigidly maintaining sameness and cuddling inside the object. PMID:7689733

  20. Microbiome change by symbiotic invasion in lichens

    NASA Astrophysics Data System (ADS)

    Maier, Stefanie; Wedin, Mats; Fernandez-Brime, Samantha; Cronholm, Bodil; Westberg, Martin; Weber, Bettina; Grube, Martin

    2016-04-01

    Alphaproteobacteria with a concomitant increase in Betaproteobacteria. Armatimonadia, Spartobacteria and Acidobacteria also decreased during the infection of Cladonia by Diploschistes. The lichens differed in photobiont specificity. C. symphycarpa was associated with the same algal species at all sites, but D. muscorum had a flexible strategy with different photobiont combinations at each site. This symbiotic invasion system suggests that partners can be reorganized in BSC and selected for maintaining potential roles rather than depending on particular species.

  1. PSR switchyard kicker system improvements

    SciTech Connect

    Hardek, T.W.

    1991-01-01

    A switchyard kicker system which allows time sharing of beam between the Los Alamos WNR/LANSCE complex and other LAMPF users was redesigned as part of the Proton Storage Ring addition. The system consists of two pulsers providing 1750-ampere, 1-msec pulses to a pair of 1 meter long ferrite magnets. The system was designed to operate at 24-Hz maximum repetition rate. In 1986 a modification was made to the equipment to allow operation at 40 Hz. While the system operated reliably this way some difficulties were observed. A desire on the part of the users to operate the system at 60 Hz coupled with a major system failure led to design changes to load resistors, drive cables, charging system, and cooling system. These changes are described along with an analysis of the difficulties encountered with the original hardware. 3 refs., 6 figs.

  2. SU Lyncis, a hard X-ray bright M giant: clues point to a large hidden population of symbiotic stars

    NASA Astrophysics Data System (ADS)

    Mukai, K.; Luna, G. J. M.; Cusumano, G.; Segreto, A.; Munari, U.; Sokoloski, J. L.; Lucy, A. B.; Nelson, T.; Nuñez, N. E.

    2016-09-01

    Symbiotic star surveys have traditionally relied almost exclusively on low resolution optical spectroscopy. However, we can obtain a more reliable estimate of their total Galactic population by using all available signatures of the symbiotic phenomenon. Here we report the discovery of a hard X-ray source, 4PBC J0642.9+5528, in the Swift hard X-ray all-sky survey, and identify it with a poorly studied red giant, SU Lyn, using pointed Swift observations and ground-based optical spectroscopy. The X-ray spectrum, the optical to UV spectrum, and the rapid UV variability of SU Lyn are all consistent with our interpretation that it is a symbiotic star containing an accreting white dwarf. The symbiotic nature of SU Lyn went unnoticed until now, because it does not exhibit emission lines strong enough to be obvious in low resolution spectra. We argue that symbiotic stars without shell-burning have weak emission lines, and that the current lists of symbiotic stars are biased in favour of shell-burning systems. We conclude that the true population of symbiotic stars has been underestimated, potentially by a large factor.

  3. Response properties of self-improving systems.

    PubMed

    Krakovsky, Andrey

    2016-04-01

    We observe that a sustained positivity (or negativity) of a system's second-order response will result in a directional change of the system's characteristics under the corresponding random exposure. We identify these changes with improvement (or decline) in the state of a system and introduce the concept of self-improving systems as systems which characteristics can sustainably improve under a random exposure. The resulting framework is of a general phenomenological nature and can be applied to complex systems across different areas of knowledge. PMID:27059562

  4. Response properties of self-improving systems

    NASA Astrophysics Data System (ADS)

    Krakovsky, Andrey

    2016-04-01

    We observe that a sustained positivity (or negativity) of a system's second-order response will result in a directional change of the system's characteristics under the corresponding random exposure. We identify these changes with improvement (or decline) in the state of a system and introduce the concept of self-improving systems as systems which characteristics can sustainably improve under a random exposure. The resulting framework is of a general phenomenological nature and can be applied to complex systems across different areas of knowledge.

  5. Searching for New Yellow Symbiotic Stars: Positive Identification of StHα63

    NASA Astrophysics Data System (ADS)

    Baella, N. O.; Pereira, C. B.; Miranda, L. F.; Alvarez-Candal, A.

    2016-04-01

    Yellow symbiotic stars are useful targets for probing whether mass transfer has happened in their binary systems. However, the number of known yellow symbiotic stars is very scarce. We report spectroscopic observations of five candidate yellow symbiotic stars that were selected by their positions in the 2MASS (J - H) versus (H - Ks) diagram and which were included in some emission-line catalogs. Among the five candidates, only StHα63 is identified as a new yellow symbiotic star because of its spectrum and its position in the [TiO]1-[TiO]2 diagram, which indicates a K4-K6 spectral type. In addition, the derived electron density (˜108.4 cm-3) and several emission-line intensity ratios provide further support for that classification. The other four candidates are rejected as symbiotic stars because three of them actually do not show emission lines and the fourth one only Balmer emission lines. We also found that the WISE W3-W4 index clearly separates normal K-giants from yellow symbiotic stars and therefore can be used as an additional tool for selecting candidate yellow symbiotic stars. Based on observations collected at the Centro Astronómico Hispano-Alemán, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie (Heidelberg) and the Instituto de Astrofísica de Andalucía (CSIC), and at the 4.1 m telescope at Cerro Pachón Observatory, Chile.

  6. A multi-frequency study of symbiotic stars. I - Near-simultaneous optical and radio observations

    NASA Astrophysics Data System (ADS)

    Ivison, R. J.; Bode, M. F.; Roberts, J. A.; Meaburn, J.; Davis, R. J.; Nelson, R. F.; Spencer, R. E.

    1991-03-01

    The relationship between optical line flux and 5 GHz radio flux is investigated for a sample of 17 northern sky symbiotic stars. Data were obtained near-simultaneously with the Manchester Echelle Spectrograph mounted on the Issac Newton Telescope, La Palma and the Broad Band Interferometer at Jodrell Bank. Color excesses, calculated from Balmer hydrogen line fluxes assuming Case B recombination ratios, are compared with other reddening estimates and also combined with extinction maps to provide improved distance estimates. Optical line fluxes are used in combination with radio fluxes to estimate physical parameters of these objects, including mass-loss rates. The suggestion that the ionized regions of D-type symbiotics are much more extensive than those in S-type is confirmed. This in turn strengthens the hypothesis that S-type symbiotics are more likely to be undergoing Roche-lobe overflow than their D-type counterparts.

  7. Overview of the observations of symbiotic stars

    NASA Technical Reports Server (NTRS)

    Viotti, Roberto

    1993-01-01

    The term Symbiotic stars commonly denotes variable stars whose optical spectra simultaneously present a cool absorption spectrum (typically TiO absorption bands) and emission lines of high ionization energy. This term is now used for the category of variable stars with composite spectrum. The main spectral features of these objects are: (1) the presence of the red continuum typical of a cool star, (2) the rich emission line spectrum, and (3) the UV excess, frequently with the Balmer continuum in emission. In addition to the peculiar spectrum, the very irregular photometric and spectroscopic variability is the major feature of the symbiotic stars. Moreover, the light curve is basic to identify the different phases of activity in a symbiotic star. The physical mechanisms that cause the symbiotic phenomenon and its variety are the focus of this paper. An astronomical phenomenon characterized by a composite stellar spectrum with two apparently conflicting features, and large variability has been observed. Our research set out to find the origin of this behavior and, in particular, to identify and measure the physical mechanism(s) responsible for the observed phenomena.

  8. Genomic and Cellular Complexity from Symbiotic Simplicity

    PubMed Central

    Bordenstein, Seth R.

    2015-01-01

    The more that biologists study symbiotic microorganisms and their vast influence on animals, the more nature’s networkism unfolds in a continuum at different biological scales. In this issue, Van Leuven et al. illuminate how a stable and longstanding animal-microbe mutualism increased its intergenomic network without gaining any new genomes. PMID:25215482

  9. Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility

    PubMed Central

    Price, Paul A.; Tanner, Houston R.; Dillon, Brett A.; Shabab, Mohammed; Walker, Graham C.; Griffitts, Joel S.

    2015-01-01

    Legume–rhizobium pairs are often observed that produce symbiotic root nodules but fail to fix nitrogen. Using the Sinorhizobium meliloti and Medicago truncatula symbiotic system, we previously described several naturally occurring accessory plasmids capable of disrupting the late stages of nodule development while enhancing bacterial proliferation within the nodule. We report here that host range restriction peptidase (hrrP), a gene found on one of these plasmids, is capable of conferring both these properties. hrrP encodes an M16A family metallopeptidase whose catalytic activity is required for these symbiotic effects. The ability of hrrP to suppress nitrogen fixation is conditioned upon the genotypes of both the host plant and the hrrP-expressing rhizobial strain, suggesting its involvement in symbiotic communication. Purified HrrP protein is capable of degrading a range of nodule-specific cysteine-rich (NCR) peptides encoded by M. truncatula. NCR peptides are crucial signals used by M. truncatula for inducing and maintaining rhizobial differentiation within nodules, as demonstrated in the accompanying article [Horváth B, et al. (2015) Proc Natl Acad Sci USA, 10.1073/pnas.1500777112]. The expression pattern of hrrP and its effects on rhizobial morphology are consistent with the NCR peptide cleavage model. This work points to a symbiotic dialogue involving a complex ensemble of host-derived signaling peptides and bacterial modifier enzymes capable of adjusting signal strength, sometimes with exploitative outcomes. PMID:26401024

  10. Plant-Associated Symbiotic Burkholderia Species Lack Hallmark Strategies Required in Mammalian Pathogenesis

    PubMed Central

    Fong, Stephanie; Yerrapragada, Shailaja; Estrada-de los Santos, Paulina; Yang, Paul; Song, Nannie; Kano, Stephanie; de Faria, Sergio M.; Dakora, Felix D.; Weinstock, George; Hirsch, Ann M.

    2014-01-01

    Burkholderia is a diverse and dynamic genus, containing pathogenic species as well as species that form complex interactions with plants. Pathogenic strains, such as B. pseudomallei and B. mallei, can cause serious disease in mammals, while other Burkholderia strains are opportunistic pathogens, infecting humans or animals with a compromised immune system. Although some of the opportunistic Burkholderia pathogens are known to promote plant growth and even fix nitrogen, the risk of infection to infants, the elderly, and people who are immunocompromised has not only resulted in a restriction on their use, but has also limited the application of non-pathogenic, symbiotic species, several of which nodulate legume roots or have positive effects on plant growth. However, recent phylogenetic analyses have demonstrated that Burkholderia species separate into distinct lineages, suggesting the possibility for safe use of certain symbiotic species in agricultural contexts. A number of environmental strains that promote plant growth or degrade xenobiotics are also included in the symbiotic lineage. Many of these species have the potential to enhance agriculture in areas where fertilizers are not readily available and may serve in the future as inocula for crops growing in soils impacted by climate change. Here we address the pathogenic potential of several of the symbiotic Burkholderia strains using bioinformatics and functional tests. A series of infection experiments using Caenorhabditis elegans and HeLa cells, as well as genomic characterization of pathogenic loci, show that the risk of opportunistic infection by symbiotic strains such as B. tuberum is extremely low. PMID:24416172

  11. Symbiotic variable V4018 Sgr in outburst

    NASA Astrophysics Data System (ADS)

    Elizabeth O. Waagen

    2012-09-01

    The symbiotic variable V4018 Sgr is undergoing an outburst, according to observations reported to the AAVSO and confirmed by spectroscopy by Ulisse Munari et al. Prompted by an observation and comment from John Bortle (Stormville, NY) (16 June 2012, visual magnitude 12.2) about a possible outburst, Steven O'Connor (St. George's, Bermuda) obtained an observation (10 August 2012, 11.44V) that confirmed V4018 Sgr was bright. His subsequent BVRI observations in September and visual observations by Bortle and Andrew Pearce (Nedlands, Western Australia) show the system brightening and at V magnitude 11.07 as of 2012 Sep. 17.091 UT. Ulisse Munari (INAF Astr. Obs. Padua, Italy) and colleagues Paolo Valisa and Sergio Dallaporta (ANS Collaboration), after being informed by the AAVSO of the bright state of V4018 Sgr, carried out spectroscopy. Munari writes: "A low resolution, absolutely fluxed 4000-8650 Ang spectrum of V4018 Sgr was obtained on Sept 13.90 UT with the 0.6m telescope ! of the Schiaparelli Observatory in Varese (Italy). It shows the spectrum of the M giant overwhelmed by a blue continuum up to 6000 Ang, and all high ionization emission lines typical of quiescence are gone, leaving only hydrogen Balmer and weak HeI lines in emission. The spectrum looks like a template one for a symbiotic star in outburst. CCD photometry was obtained on Sept 13.79 UT and provides V=11.027 ± 0.002, B-V=+0.621 ± 0.003. The B-V color is appreciably bluer and the V magnitude much brighter than typical in quiescence (on average V=13.3, B-V=+1.09; Henden and Munari 2008, Baltic Astronomy 17, 293), and support the idea V4018 Sgr is undergoing an outburst." According to Munari, the last bright outburst of V4018 Sgr was underway in June 1990. Observations in the AAVSO International Database from Albert Jones (Nelson, New Zealand) beginning in May 1992 show the variable at visual magnitude 11.0, with fluctuations between 10.5 and 11.9 through October 1995. Numerous ! other observers

  12. Quality improvement in population health systems.

    PubMed

    Inkelas, Moira; McPherson, Marianne E

    2015-12-01

    Quality improvement methods have achieved large sustainable changes in health care quality and health outcomes. Transforming health care into a population health system requires methods for innovation and improvement that can work across professions and sectors. It may be possible to replicate improvement successes in healthcare settings within and across the broader systems of social, educational, and other human services that influence health outcomes in communities. Improvement methods could translate the rhetoric of collaboration, integration and alignment into practice across the fragmented health and human service sectors in the U.S. PMID:26699349

  13. Hydrodynamical simulations of the jet in the symbiotic star MWC 560. I. Structure, emission and synthetic absorption line profiles

    NASA Astrophysics Data System (ADS)

    Stute, M.; Camenzind, M.; Schmid, H. M.

    2005-01-01

    We performed hydrodynamical simulations with and without radiative cooling of jet models with parameters representative of the symbiotic system MWC 560. For symbiotic systems we have to perform jet simulations of a pulsed underdense jet in a high density ambient medium. We present the jet structure resulting from our simulations and calculate emission plots which account for expected radiative processes. In addition, our calculations provide expansion velocities for the jet bow shock, the density and temperature structure in the jet, and the propagation and evolution of the jet pulses. In MWC 560 the jet axis is parallel to the line of sight so that the outflowing jet gas can be seen as blue shifted, variable absorption lines in the continuum of the underlying jet source. Based on our simulations we calculate and discuss synthetic absorption profiles. Based on a detailed comparison between model spectra and observations we discuss our hydrodynamical calculations for a pulsed jet in MWC 560 and suggest improvements for future models. Figures \\ref{skizze}, \\ref{modi_det}, \\ref{slice_cool_p}, \\ref{NV_3.0_synch}, \\ref{modelicool_greyscale}, \\ref{line_rem}-\\ref{line_dv} and \\ref{line_zmax} are only available in electronic form at http://www.edpsciences.org

  14. Symbiotic options for the conquest of land.

    PubMed

    Field, Katie J; Pressel, Silvia; Duckett, Jeffrey G; Rimington, William R; Bidartondo, Martin I

    2015-08-01

    The domination of the landmasses of Earth by plants starting during the Ordovician Period drastically altered the development of the biosphere and the composition of the atmosphere, with far-reaching consequences for all life ever since. It is widely thought that symbiotic soil fungi facilitated the colonization of the terrestrial environment by plants. However, recent discoveries in molecular ecology, physiology, cytology, and paleontology have brought into question the hitherto-assumed identity and biology of the fungi engaged in symbiosis with the earliest-diverging lineages of extant land plants. Here, we reconsider the existing paradigm and show that the symbiotic options available to the first plants emerging onto the land were more varied than previously thought. PMID:26111583

  15. Molecular Determinants of a Symbiotic Chronic Infection

    PubMed Central

    Gibson, Katherine E.; Kobayashi, Hajime

    2009-01-01

    Rhizobial bacteria colonize legume roots for the purpose of biological nitrogen fixation. A complex series of events, coordinated by host and bacterial signal molecules, underlie the development of this symbiotic interaction. Rhizobia elicit de novo formation of a novel root organ within which they establish a chronic intracellular infection. Legumes permit rhizobia to invade these root tissues while exerting control over the infection process. Once rhizobia gain intracellular access to their host, legumes also strongly influence the process of bacterial differentiation that is required for nitrogen fixation. Even so, symbiotic rhizobia play an active role in promoting their goal of host invasion and chronic persistence by producing a variety of signal molecules that elicit changes in host gene expression. In particular, rhizobia appear to advocate for their access to the host by producing a variety of signal molecules capable of suppressing a general pathogen defense response. PMID:18983260

  16. Isolation of symbiotic dinoflagellates by centrifugal elutriation

    SciTech Connect

    Bird, A.E.; Quinn, R.J.

    1986-01-01

    Centrifugal elutriation, a method combining centripetal liquid flow with centrifugal force, has been used to isolate symbiotic dinoflagellates from a cnidarian host. The elutriated cells were shown to be viable by photosynthetic incorporation of /sup 14/CO/sub 2/ and low release of photosynthetic products into the incubation medium. The level of contamination by clinging debris was low and by host solids was negligible.

  17. An improved instantaneous laser Doppler velocity system

    NASA Astrophysics Data System (ADS)

    Desio, Charles V.; Olcmen, Semih; Schinetsky, Philip

    2016-02-01

    In this paper, improvements made on a single velocity component instantaneous laser Doppler velocimetry (ILDV) system are detailed. The ILDV system developed in this research effort is capable of measuring a single velocity component at a rate as high as two megahertz. The current system accounts for the effects of the laser intensity variation on the measured velocity and eliminates the use of a Pockels cell used in previous ILDV systems. The system developed in the current effort was tested using compressible, subsonic jet flows. The ILDV system developed would be most beneficial where a high data capture rate is needed such as in shock tubes, and high-speed wind tunnels.

  18. A simple framework for complex system improvement.

    PubMed

    Kraft, Sally; Carayon, Pascale; Weiss, Jennifer; Pandhi, Nancy

    2015-05-01

    The need to rapidly improve health care value is unquestioned, but the means to accomplish this task is unknown. Improving performance at the level of the health care organization frequently involves multiple interventions, which must be coordinated and sequenced to fit the specific context. Those responsible for achieving large-scale improvements are challenged by the lack of a framework to describe and organize improvement strategies. Drawing from the fields of health services, industrial engineering, and organizational behavior, a simple framework was developed and has been used to guide and evaluate improvement initiatives at an academic health center. The authors anticipate that this framework will be helpful for health system leaders responsible for improving health care quality. PMID:24723664

  19. Improving College System Pathways: Project Highlights Reports

    ERIC Educational Resources Information Center

    Colleges Ontario, 2008

    2008-01-01

    In 2006, Ontario's colleges received funding from the Ministry of Training, Colleges and Universities for the Improving College System Pathways Project. The project goals were to significantly increase educational pathways within and between colleges by developing a clearer understanding of student mobility within the system; to identify the scope…

  20. Improving Ohio's Education Management Information System (EMIS).

    ERIC Educational Resources Information Center

    Ohio State Legislative Office of Education Oversight, Columbus.

    Due to legislative mandate, the Ohio Department of Education (ODE) was required to develop a system (the Education Management Information System) that would increase the amount of information available to state-level policy makers and the public. Some recommendations for improving the function of EMIS are offered in this report. The text provides…

  1. Non-symbiotic Bradyrhizobium ecotypes dominate North American forest soils.

    PubMed

    VanInsberghe, David; Maas, Kendra R; Cardenas, Erick; Strachan, Cameron R; Hallam, Steven J; Mohn, William W

    2015-11-01

    The genus Bradyrhizobium has served as a model system for studying host-microbe symbiotic interactions and nitrogen fixation due to its importance in agricultural productivity and global nitrogen cycling. In this study, we identify a bacterial group affiliated with this genus that dominates the microbial communities of coniferous forest soils from six distinct ecozones across North America. Representative isolates from this group were obtained and characterized. Using quantitative population genomics, we show that forest soil populations of Bradyrhizobium represent ecotypes incapable of nodulating legume root hairs or fixing atmospheric nitrogen. Instead, these populations appear to be free living and have a greater potential for metabolizing aromatic carbon sources than their close symbiotic relatives. In addition, we identify fine-scaled differentiation between populations inhabiting neighboring soil layers that illustrate how diversity within Bradyrhizobium is structured by habitat similarity. These findings reconcile incongruent observations about this widely studied and important group of bacteria and highlight the value of ecological context to interpretations of microbial diversity and taxonomy. These results further suggest that the influence of this genus likely extends well beyond facilitating agriculture, especially as forest ecosystems are large and integral components of the biosphere. In addition, this study demonstrates how focusing research on economically important microorganisms can bias our understanding of the natural world. PMID:25909973

  2. Symbiotic crabs maintain coral health by clearing sediments

    NASA Astrophysics Data System (ADS)

    Stewart, Hannah L.; Holbrook, Sally J.; Schmitt, Russell J.; Brooks, Andrew J.

    2006-11-01

    Stony corals are the foundation of coral reef ecosystems and form associations with other reef species. Many of these associations may be ecologically important and play a role in maintaining the health and diversity of reef systems, rendering it critical to understand the influence of symbiotic organisms in mediating responses to perturbation. This study demonstrates the importance of an association with trapeziid crabs in reducing adverse effects of sediments deposited on corals. In a field experiment, mortality rates of two species of branching corals were significantly lowered by the presence of crabs. All outplanted corals with crabs survived whereas 45-80% of corals without crabs died within a month. For surviving corals that lacked crabs, growth was slower and tissue bleaching and sediment load were higher. Laboratory experiments revealed that corals with crabs shed substantially more of the sediments deposited on coral surfaces, but also that crabs were most effective at removing grain sizes that were most damaging to coral tissues. The mechanism underlying this symbiotic relationship has not been recognized previously, and its role in maintaining coral health is likely to become even more critical as reefs worldwide experience increasing sedimentation.

  3. Extensive Differences in Gene Expression Between Symbiotic and Aposymbiotic Cnidarians

    PubMed Central

    Lehnert, Erik M.; Mouchka, Morgan E.; Burriesci, Matthew S.; Gallo, Natalya D.; Schwarz, Jodi A.; Pringle, John R.

    2013-01-01

    Coral reefs provide habitats for a disproportionate number of marine species relative to the small area of the oceans that they occupy. The mutualism between the cnidarian animal hosts and their intracellular dinoflagellate symbionts provides the nutritional foundation for coral growth and formation of reef structures, because algal photosynthesis can provide >90% of the total energy of the host. Disruption of this symbiosis (“coral bleaching”) is occurring on a large scale due primarily to anthropogenic factors and poses a major threat to the future of coral reefs. Despite the importance of this symbiosis, the cellular mechanisms involved in its establishment, maintenance, and breakdown remain largely unknown. We report our continued development of genomic tools to study these mechanisms in Aiptasia, a small sea anemone with great promise as a model system for studies of cnidarian–dinoflagellate symbiosis. Specifically, we have generated de novo assemblies of the transcriptomes of both a clonal line of symbiotic anemones and their endogenous dinoflagellate symbionts. We then compared transcript abundances in animals with and without dinoflagellates. This analysis identified >900 differentially expressed genes and allowed us to generate testable hypotheses about the cellular functions affected by symbiosis establishment. The differentially regulated transcripts include >60 encoding proteins that may play roles in transporting various nutrients between the symbiotic partners; many more encoding proteins functioning in several metabolic pathways, providing clues regarding how the transported nutrients may be used by the partners; and several encoding proteins that may be involved in host recognition and tolerance of the dinoflagellate. PMID:24368779

  4. Improvements to information management systems simulator

    NASA Technical Reports Server (NTRS)

    Bilek, R. W.

    1972-01-01

    The performance of personnel in the augmentation and improvement of the interactive IMSIM information management simulation model is summarized. With this augmented model, NASA now has even greater capabilities for the simulation of computer system configurations, data processing loads imposed on these configurations, and executive software to control system operations. Through these simulations, NASA has an extremely cost effective capability for the design and analysis of computer-based data management systems.

  5. Improved Interactive Medical-Imaging System

    NASA Technical Reports Server (NTRS)

    Ross, Muriel D.; Twombly, Ian A.; Senger, Steven

    2003-01-01

    An improved computational-simulation system for interactive medical imaging has been invented. The system displays high-resolution, three-dimensional-appearing images of anatomical objects based on data acquired by such techniques as computed tomography (CT) and magnetic-resonance imaging (MRI). The system enables users to manipulate the data to obtain a variety of views for example, to display cross sections in specified planes or to rotate images about specified axes. Relative to prior such systems, this system offers enhanced capabilities for synthesizing images of surgical cuts and for collaboration by users at multiple, remote computing sites.

  6. Improved MFCC algorithm in speaker recognition system

    NASA Astrophysics Data System (ADS)

    Shi, Yibo; Wang, Li

    2011-10-01

    In speaker recognition systems, one of the key feature parameters is MFCC, which can be used for speaker recognition. So, how to extract MFCC parameter in speech signals more exactly and efficiently, decides the performance of the system. Theoretically, MFCC parameters are used to describe the spectrum envelope of the vocal tract characteristics and often ignore the impacts of fundamental frequency. But in practice, MFCC can be influenced by fundamental frequency which can cause palpable performance reduction. So, smoothing MFCC (SMFCC), which based on smoothing short-term spectral amplitude envelope, has been proposed to improve MFCC algorithm. Experimental results show that improved MFCC parameters---SMFCC can degrade the bad influences of fundamental frequency effectively and upgrade the performances of speaker recognition system. Especially for female speakers, who have higher fundamental frequency, the recognition rate improves more significantly.

  7. Improved All-Terrain Suspension System

    NASA Technical Reports Server (NTRS)

    Bickler, Donald B.

    1994-01-01

    Redesigned suspension system for all-terrain vehicle exhibits enhanced ability to negotiate sand and rocks. Improved six-wheel suspension system includes only two links on each side. Bogie tends to pull rear wheels with it as it climbs. Designed for rover vehicle for exploration of Mars, also has potential application in off-road vehicles, military scout vehicles, robotic emergency vehicles, and toys. Predecessors of suspension system described in "Articulated Suspension Without Springs" (NPO-17354), "Four-Wheel Vehicle Suspension System" (NPO-17407), and "High-Clearance Six-Wheel Suspension" (NPO-17821).

  8. Compensator improvement for multivariable control systems

    NASA Technical Reports Server (NTRS)

    Mitchell, J. R.; Mcdaniel, W. L., Jr.; Gresham, L. L.

    1977-01-01

    A theory and the associated numerical technique are developed for an iterative design improvement of the compensation for linear, time-invariant control systems with multiple inputs and multiple outputs. A strict constraint algorithm is used in obtaining a solution of the specified constraints of the control design. The result of the research effort is the multiple input, multiple output Compensator Improvement Program (CIP). The objective of the Compensator Improvement Program is to modify in an iterative manner the free parameters of the dynamic compensation matrix so that the system satisfies frequency domain specifications. In this exposition, the underlying principles of the multivariable CIP algorithm are presented and the practical utility of the program is illustrated with space vehicle related examples.

  9. State Systems Improvement Self-Assessment

    ERIC Educational Resources Information Center

    Mid-South Regional Resource Center (MSRRC), 2008

    2008-01-01

    This document was developed by the Mid-South Regional Resource Center (MSRRC) and is designed to be used as an assessment of State systems by State Part B and Part C staff and their stakeholders. It provides a detailed process for State Education Agencies (SEA) and Lead Agencies (LA) to follow that will guide improvement efforts relative to the…

  10. New camera tube improves ultrasonic inspection system

    NASA Technical Reports Server (NTRS)

    Berger, H.; Collis, W. J.; Jacobs, J. E.

    1968-01-01

    Electron multiplier, incorporated into the camera tube of an ultrasonic imaging system, improves resolution, effectively shields low level circuits, and provides a high level signal input to the television camera. It is effective for inspection of metallic materials for bonds, voids, and homogeneity.

  11. A challenging future for improved photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Allen, Douglas M.

    The expansion of space requirements creates opportunities and priorities for power production, thus driving the development of innovative technologies. Key requirements for improving photovoltaics are outlined including cell efficiency, specific power, packaging, reliability, and affordability issues. The competition faced by photovoltaic cells is discussed with specific reference to solar dynamics and nuclear radioisotope thermal generator systems.

  12. Progress in photovoltaic system and component improvements

    SciTech Connect

    Thomas, H.P.; Kroposki, B.; McNutt, P.; Witt, C.E.; Bower, W.; Bonn, R.; Hund, T.D.

    1998-07-01

    The Photovoltaic Manufacturing Technology (PVMaT) project is a partnership between the US government (through the US Department of Energy [DOE]) and the PV industry. Part of its purpose is to conduct manufacturing technology research and development to address the issues and opportunities identified by industry to advance photovoltaic (PV) systems and components. The project was initiated in 1990 and has been conducted in several phases to support the evolution of PV industrial manufacturing technology. Early phases of the project stressed PV module manufacturing. Starting with Phase 4A and continuing in Phase 5A, the goals were broadened to include improvement of component efficiency, energy storage and manufacturing and system or component integration to bring together all elements for a PV product. This paper summarizes PV manufacturers` accomplishments in components, system integration, and alternative manufacturing methods. Their approaches have resulted in improved hardware and PV system performance, better system compatibility, and new system capabilities. Results include new products such as Underwriters Laboratories (UL)-listed AC PV modules, modular inverters, and advanced inverter designs that use readily available and standard components. Work planned in Phase 5A1 includes integrated residential and commercial roof-top systems, PV systems with energy storage, and 300-Wac to 4-kWac inverters.

  13. Improving reservoir conformance using gelled polymer systems

    SciTech Connect

    Green, D.W.; Willhite, G.P.

    1993-04-09

    The general objectives are to (1) to identify and develop gelled polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) to determine the performance of these systems in bulk and in porous media, and (3) to develop methods to predict the capability of these systems to recover oil from petroleum reservoirs. This work focuses on three types of gel systems - an aqueous polysaccharide (KUSPI) system that gels as a function of pH, the chromium-based system where polyacrylamide and xanthan are crosslinked by CR(III) and an organic crosslinked system. Development of the KUSPI system and evaluation and identification of a suitable organic crosslinked system will be done. The laboratory research is directed at the fundamental understanding of the physics and chemistry of the gelation process in bulk form and in porous media. This knowledge will be used to develop conceptual and mathematical models of the gelation process. Mathematical models will then be extended to predict the performance of gelled polymer treatments in oil reservoirs. Accomplishments for this period are presented for the following tasks: development and selection of gelled polymer systems, physical and chemical characterization of gel systems; and mathematical modeling of gel systems.

  14. Improving reservoir conformance using gelled polymer systems

    SciTech Connect

    Green, D.W.; Willhite, P.G.

    1992-12-25

    The general objectives are to (1) to identify and develop gelled polymer systems which have potential to improve reservoir conformance of fluid displacement processes, (2) to determine the performance of these systems in bulk and in porous media, and (3) to develop methods to predict the capability of these systems to recover oil from petroleum reservoirs. This work focuses on three types of gel systems -- an aqueous polysaccharide (KUSP1) system that gels as a function of pH, the chromium-based system where polyacrylamide and xanthan are crosslinked by Cr(III) and an organic crosslinked system. Development of the KUSP1 system and evaluation and, identification of the organic crosslinked system will be conducted. The laboratory research is directed at the fundamental understanding of the physics and chemistry of the gelation process in bulk form and in porous media. This knowledge will be used to develop conceptual and mathematical models of the gelation process. Mathematical models will then be extended to predict the performance of gelled polymer treatments in oil reservoirs. Progress report are presented for the following tasks: Development and selection of gelled polymer systems; physical and chemical characterization of gel systems; and mathematical modelling of gel systems.

  15. Profile disparity of Raman-scattered O VI in symbiotic stars

    NASA Astrophysics Data System (ADS)

    Lee, Hee-Won

    2016-07-01

    Symbiotic stars are wide binary systems consisting of a hot compact star (usually a white dwarf) and a mass losing giant. Symbiotic activities are believed to occur through gravitational capture of a fraction of the slow stellar wind from the giant. Raman scattered features of O VI resonance doublet 1032 and 1038 appearing at around 6825 Å and 7082 Å are a unique spectroscopic diagnostic tool to probe the mass transfer process in symbiotic stars. The Raman O VI features often exhibit multiple peak structures and in many cases the blue peak of 7082 features is relatively more suppressed than that of 6825 features. We propose that the disparity of the two profiles is attributed to the local variation of optical depths of O VI, implying that the accretion flow is convergent in the red emission region and divergent in the blue emission region. It is argued in this presentation that Raman scattering by atomic hydrogen is a natural mirror to provide an edge-on view of the accretion disk and a lateral view of the bipolar outflow in symbiotic stars. We discuss the spectropolarimetric implications of this interpretation.

  16. Genomic resources for identification of the minimal N2 -fixing symbiotic genome.

    PubMed

    diCenzo, George C; Zamani, Maryam; Milunovic, Branislava; Finan, Turlough M

    2016-09-01

    The lack of an appropriate genomic platform has precluded the use of gain-of-function approaches to study the rhizobium-legume symbiosis, preventing the establishment of the genes necessary and sufficient for symbiotic nitrogen fixation (SNF) and potentially hindering synthetic biology approaches aimed at engineering this process. Here, we describe the development of an appropriate system by reverse engineering Sinorhizobium meliloti. Using a novel in vivo cloning procedure, the engA-tRNA-rmlC (ETR) region, essential for cell viability and symbiosis, was transferred from Sinorhizobium fredii to the ancestral location on the S. meliloti chromosome, rendering the ETR region on pSymB redundant. A derivative of this strain lacking both the large symbiotic replicons (pSymA and pSymB) was constructed. Transfer of pSymA and pSymB back into this strain restored symbiotic capabilities with alfalfa. To delineate the location of the single-copy genes essential for SNF on these replicons, we screened a S. meliloti deletion library, representing > 95% of the 2900 genes of the symbiotic replicons, for their phenotypes with alfalfa. Only four loci, accounting for < 12% of pSymA and pSymB, were essential for SNF. These regions will serve as our preliminary target of the minimal set of horizontally acquired genes necessary and sufficient for SNF. PMID:26768651

  17. Improved Photon-Emission-Microscope System

    NASA Technical Reports Server (NTRS)

    Vu, Duc

    2006-01-01

    An improved photon-emission-microscope (PEM) instrumentation system has been developed for use in diagnosing failure conditions in semiconductor devices, including complex integrated circuits. This system is designed primarily to image areas that emit photons, at wavelengths from 400 to 1,100 nm, associated with device failures caused by leakage of electric current through SiO2 and other dielectric materials used in multilayer semiconductor structures. In addition, the system is sensitive enough to image areas that emit photons during normal operation.

  18. Improving governance to improve oral health: addressing care delivery systems.

    PubMed

    Batchelor, Paul

    2012-09-01

    The evolving role of the state in the provision of health care has seen the adoption of new management philosophies to ensure that goals set for the system are reached. In particular, the term New Public Management (NPM) has tended to dominate reforms to help address perceived shortcomings in public sector services. NPM is based on the use of freemarket type arrangements as a mechanism to solve problems, the control of which provides new challenges. One particular challenge that has arisen from the combination of NPM with the large number of agencies involved in care provision is that of addressing the issues arising from the improved understanding of the determinants of health. This has led to the evolution of differing care arrangements across differing sectors at all levels. If resources are to be used as intended, the control of delivery systems to oversee their use must exist. The overarching term for such activity is â governance. This paper provides an overview of the issues that arise for addressing governance of oral health care and the subsequent challenges that face those responsible for ensuring compliance. PMID:22976573

  19. Comparative proteomics of symbiotic and aposymbiotic juvenile soft corals.

    PubMed

    Barneah, O; Benayahu, Y; Weis, V M

    2006-01-01

    The symbiotic association between corals and photosynthetic unicellular algae is of great importance in coral reef ecosystems. The study of symbiotic relationships is multidisciplinary and involves research in phylogeny, physiology, biochemistry, and ecology. An intriguing phase in each symbiotic relationship is its initiation, in which the partners interact for the first time. The examination of this phase in coral-algae symbiosis from a molecular point of view is still at an early stage. In the present study we used 2-dimensional polyacrylamide gel electrophoresis to compare patterns of proteins synthesized in symbiotic and aposymbiotic primary polyps of the Red Sea soft coral Heteroxenia fuscescens. This is the first work to search for symbiosis-specific proteins during the natural onset of symbiosis in early host ontogeny. The protein profiles reveal changes in the host soft coral proteome through development, but surprisingly virtually no changes in the host proteome as a function of symbiotic state. PMID:16059755

  20. On the nature of the symbiotic star BF Cygni

    NASA Technical Reports Server (NTRS)

    Mikolajewska, J.; Mikolajewski, M.; Kenyon, S. J.

    1989-01-01

    Optical and ultraviolet spectroscopy of the symbiotic binary BF Cyg obtained during 1979-1988 is discussed. This system consists of a low-mass M5 giant filling about 50 percent of its tidal volume and a hot, luminous compact object similar to the central star of a planetary nebula. The binary is embedded in an asymmetric nebula which includes a small, high-density region and an extended region of lower density. The larger nebula is formed by a slow wind ejected by the cool component and ionized by the hot star, while the more compact nebula is material expelled by the hot component in the form of a bipolar wind. The analysis indicates that disk accretion is essential to maintain the nuclear burning shell of the hot star.

  1. SYMBIOTIC STAR BLOWS BUBBLES INTO SPACE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A tempestuous relationship between an unlikely pair of stars may have created an oddly shaped, gaseous nebula that resembles an hourglass nestled within an hourglass. Images taken with Earth-based telescopes have shown the larger, hourglass-shaped nebula. But this picture, taken with NASA's Hubble Space Telescope, reveals a small, bright nebula embedded in the center of the larger one (close-up of nebula in inset). Astronomers have dubbed the entire nebula the 'Southern Crab Nebula' (He2-104), because, from ground-based telescopes, it looks like the body and legs of a crab. The nebula is several light-years long. The possible creators of these shapes cannot be seen at all in this Wide Field and Planetary Camera 2 image. It's a pair of aging stars buried in the glow of the tiny, central nebula. One of them is a red giant, a bloated star that is exhausting its nuclear fuel and is shedding its outer layers in a powerful stellar wind. Its companion is a hot, white dwarf, a stellar zombie of a burned-out star. This odd duo of a red giant and a white dwarf is called a symbiotic system. The red giant is also a Mira Variable, a pulsating red giant, that is far away from its partner. It could take as much as 100 years for the two to orbit around each other. Astronomers speculate that the interaction between these two stars may have sparked episodic outbursts of material, creating the gaseous bubbles that form the nebula. They interact by playing a celestial game of 'catch': as the red giant throws off its bulk in a powerful stellar wind, the white dwarf catches some of it. As a result, an accretion disk of material forms around the white dwarf and spirals onto its hot surface. Gas continues to build up on the surface until it sparks an eruption, blowing material into space. This explosive event may have happened twice in the 'Southern Crab.' Astronomers speculate that the hourglass-shaped nebulae represent two separate outbursts that occurred several thousand years apart

  2. Rhizobium meliloti Genes Encoding Catabolism of Trigonelline Are Induced under Symbiotic Conditions.

    PubMed

    Boivin, C.; Camut, S.; Malpica, C. A.; Truchet, G.; Rosenberg, C.

    1990-12-01

    Rhizobium meliloti trc genes controlling the catabolism of trigonelline, a plant secondary metabolite often abundant in legumes, are closely linked to nif-nod genes on the symbiotic megaplasmid pSym [Boivin, C., Malpica, C., Rosenberg, C., Denarie, J., Goldman, A., Fleury, V., Maille, M., Message, B., and Tepfer, D. (1989). In Molecular Signals in the Microbe-Plant Symbiotic and Pathogenic Systems. (Berlin: Springer-Verlag), pp. 401-407]. To investigate the role of trigonelline catabolism in the Rhizobium-legume interaction, we studied the regulation of trc gene expression in free-living and in endosymbiotic bacteria using Escherichia coli lacZ as a reporter gene. Experiments performed with free-living bacteria indicated that trc genes were organized in at least four transcription units and that the substrate trigonelline was a specific inducer for three of them. Noninducing trigonelline-related compounds such as betaines appeared to antagonize the inducing effect of trigonelline. None of the general or symbiotic regulatory genes ntrA, dctB/D, or nodD seemed to be involved in trigonelline catabolism. trc fusions exhibiting a low basal and a high induced [beta]-galactosidase activity when present on pSym were used to monitor trc gene expression in alfalfa tissue under symbiotic conditions. Results showed that trc genes are induced during all the symbiotic steps, i.e., in the rhizosphere, infection threads, and bacteroids of alfalfa, suggesting that trigonelline is a nutrient source throughout the Rhizobium-legume association. PMID:12354952

  3. Exploring the symbiotic pangenome of the nitrogen-fixing bacterium Sinorhizobium meliloti

    SciTech Connect

    Galardini, Marco; Mengoni, Alessio; Brilli, Matteo; Pini, Francesco; Fioravanti, Antonella; Lucas, Susan; Lapidus, Alla L.; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Sam; Land, Miriam L; Hauser, Loren John; Woyke, Tanja; Mikhailova, Natalia; Ivanova, N; Daligault, Hajnalka E.; Bruce, David; Detter, J. Chris; Tapia, Roxanne; Han, Cliff; Teshima, Hazuki; Mocali, Stefano; Bazzicalupo, Marco; Biondi, Emanuele

    2011-01-01

    Background: Sinorhizobium meliloti is a model system for the studies of symbiotic nitrogen fixation. An extensive polymorphism at the genetic and phenotypic level is present in natural populations of this species, especially in relation with symbiotic promotion of plant growth. AK83 and BL225C are two nodule-isolated strains with diverse symbiotic phenotypes; BL225C is more efficient in promoting growth of the Medicago sativa plants than strain AK83. In order to investigate the genetic determinants of the phenotypic diversification of S. meliloti strains AK83 and BL225C, we sequenced the complete genomes for these two strains. Results: With sizes of 7.14 Mbp and 6.97 Mbp, respectively, the genomes of AK83 and BL225C are larger than the laboratory strain Rm1021. The core genome of Rm1021, AK83, BL225C strains included 5124 orthologous groups, while the accessory genome was composed by 2700 orthologous groups. While Rm1021 and BL225C have only three replicons (Chromosome, pSymA and pSymB), AK83 has also two plasmids, 260 and 70 Kbp long. We found 65 interesting orthologous groups of genes that were present only in the accessory genome, consequently responsible for phenotypic diversity and putatively involved in plant-bacterium interaction. Notably, the symbiosis inefficient AK83 lacked several genes required for microaerophilic growth inside nodules, while several genes for accessory functions related to competition, plant invasion and bacteroid tropism were identified only in AK83 and BL225C strains. Presence and extent of polymorphism in regulons of transcription factors involved in symbiotic interaction were also analyzed. Our results indicate that regulons are flexible, with a large number of accessory genes, suggesting that regulons polymorphism could also be a key determinant in the variability of symbiotic performances among the analyzed strains.

  4. Systems Improved Numerical Fluids Analysis Code

    NASA Technical Reports Server (NTRS)

    Costello, F. A.

    1990-01-01

    Systems Improved Numerical Fluids Analysis Code, SINFAC, consists of additional routines added to April, 1983, version of SINDA. Additional routines provide for mathematical modeling of active heat-transfer loops. Simulates steady-state and pseudo-transient operations of 16 different components of heat-transfer loops, including radiators, evaporators, condensers, mechanical pumps, reservoirs, and many types of valves and fittings. Program contains property-analysis routine used to compute thermodynamic properties of 20 different refrigerants. Source code written in FORTRAN 77.

  5. Fixating on metals: new insights into the role of metals in nodulation and symbiotic nitrogen fixation

    PubMed Central

    González-Guerrero, Manuel; Matthiadis, Anna; Sáez, Áez;ngela; Long, Terri A.

    2014-01-01

    Symbiotic nitrogen fixation is one of the most promising and immediate alternatives to the overuse of polluting nitrogen fertilizers for improving plant nutrition. At the core of this process are a number of metalloproteins that catalyze and provide energy for the conversion of atmospheric nitrogen to ammonia, eliminate free radicals produced by this process, and create the microaerobic conditions required by these reactions. In legumes, metal cofactors are provided to endosymbiotic rhizobia within root nodule cortical cells. However, low metal bioavailability is prevalent in most soils types, resulting in widespread plant metal deficiency and decreased nitrogen fixation capabilities. As a result, renewed efforts have been undertaken to identify the mechanisms governing metal delivery from soil to the rhizobia, and to determine how metals are used in the nodule and how they are recycled once the nodule is no longer functional. This effort is being aided by improved legume molecular biology tools (genome projects, mutant collections, and transformation methods), in addition to state-of-the-art metal visualization systems. PMID:24592271

  6. Improved Airborne System for Sensing Wildfires

    NASA Technical Reports Server (NTRS)

    McKeown, Donald; Richardson, Michael

    2008-01-01

    The Wildfire Airborne Sensing Program (WASP) is engaged in a continuing effort to develop an improved airborne instrumentation system for sensing wildfires. The system could also be used for other aerial-imaging applications, including mapping and military surveillance. Unlike prior airborne fire-detection instrumentation systems, the WASP system would not be based on custom-made multispectral line scanners and associated custom- made complex optomechanical servomechanisms, sensors, readout circuitry, and packaging. Instead, the WASP system would be based on commercial off-the-shelf (COTS) equipment that would include (1) three or four electronic cameras (one for each of three or four wavelength bands) instead of a multispectral line scanner; (2) all associated drive and readout electronics; (3) a camera-pointing gimbal; (4) an inertial measurement unit (IMU) and a Global Positioning System (GPS) receiver for measuring the position, velocity, and orientation of the aircraft; and (5) a data-acquisition subsystem. It would be necessary to custom-develop an integrated sensor optical-bench assembly, a sensor-management subsystem, and software. The use of mostly COTS equipment is intended to reduce development time and cost, relative to those of prior systems.

  7. Improving Systemic Chemotherapy for Bladder Cancer.

    PubMed

    Rose, Tracy L; Milowsky, Matthew I

    2016-05-01

    Systemic chemotherapy is integral to the management of muscle-invasive and metastatic bladder cancer (BCa). Neoadjuvant chemotherapy has been increasingly utilized for muscle-invasive BCa over the past several years, and several options for cisplatin-based regimens have emerged. Adjuvant chemotherapy may be considered for select patients who did not receive neoadjuvant therapy. Systemic chemotherapy added to radiotherapy is a critical component of a bladder-preserving approach and superior to radiotherapy alone. Cisplatin-based chemotherapy has been the mainstay for metastatic BCa for more than three decades. Novel targeted agents are in development fueled by the recent molecular characterization of BCa. Recent trials of immunotherapy have demonstrated the possibility of a less toxic and potentially more effective treatment for metastatic disease. It is an extremely exciting time for BCa research, and much needed improvements in systemic treatment are most certainly on the horizon. PMID:26984414

  8. Improving subsurface hydrology in Earth System Models

    NASA Astrophysics Data System (ADS)

    Volk, J. M.; Clark, M. P.; Swenson, S. C.; Lawrence, D. M.; Tyler, S. W.

    2015-12-01

    Hydrologic processes that govern storage and transport of soil water and groundwater can have strong dynamic relationships with biogeochemical and atmospheric processes. This understanding has lead to a push to improve subsurface hydrologic parametrization in Earth System Models. Here we present results related to improving the implementation of soil moisture distribution, groundwater recharge/discharge, and subsurface drainage in the Community Land Model (CLM) which is the land surface model in the Community Earth System Model. First we identified geo-climatically different locations around the world to develop test cases. For each case we compare the vertical soil moisture distribution from the different implementations of 1D Richards equation, considering the boundary conditions, the treatment of the groundwater sink term, the vertical discretization, and the time stepping schemes. Generally, large errors in the hydrologic mass balance within the soil column occur when there is a large vertical gradient in soil moisture or when there is a shallow water table within a soil column. We then test the sensitivity of the algorithmic parameters that control temporal discretization and error tolerance of the adaptive time-stepping scheme to help optimize its computational efficiency. In addition, we vary the spatial discretization of soil layers (i.e. quantity of layers and their thicknesses) to better understand the sensitivity of vertical discretization of soil columns on soil moisture variability in ESMs. We present multivariate and multi-scale evaluation for the different model options and suggest ways to move forward with future model improvements.

  9. Phylogeny of Symbiotic Genes and the Symbiotic Properties of Rhizobia Specific to Astragalus glycyphyllos L.

    PubMed Central

    Gnat, Sebastian; Małek, Wanda; Oleńska, Ewa; Wdowiak-Wróbel, Sylwia; Kalita, Michał; Łotocka, Barbara; Wójcik, Magdalena

    2015-01-01

    The phylogeny of symbiotic genes of Astragalus glycyphyllos L. (liquorice milkvetch) nodule isolates was studied by comparative sequence analysis of nodA, nodC, nodH and nifH loci. In all these genes phylograms, liquorice milkvetch rhizobia (closely related to bacteria of three species, i.e. Mesorhizobium amorphae, Mesorhizobium septentrionale and Mesorhizobium ciceri) formed one clearly separate cluster suggesting the horizontal transfer of symbiotic genes from a single ancestor to the bacteria being studied. The high sequence similarity of the symbiotic genes of A. glycyphyllos rhizobia (99–100% in the case of nodAC and nifH genes, and 98–99% in the case of nodH one) points to the relatively recent (in evolutionary scale) lateral transfer of these genes. In the nodACH and nifH phylograms, A. glycyphyllos nodule isolates were grouped together with the genus Mesorhizobium species in one monophyletic clade, close to M. ciceri, Mesorhizobium opportunistum and Mesorhizobium australicum symbiovar biserrulae bacteria, which correlates with the close relationship of these rhizobia host plants. Plant tests revealed the narrow host range of A. glycyphyllos rhizobia. They formed effective symbiotic interactions with their native host (A. glycyphyllos) and Amorpha fruticosa but not with 11 other fabacean species. The nodules induced on A. glycyphyllos roots were indeterminate with apical, persistent meristem, an age gradient of nodule tissues and cortical vascular bundles. To reflect the symbiosis-adaptive phenotype of rhizobia, specific for A. glycyphyllos, we propose for these bacteria the new symbiovar “glycyphyllae”, based on nodA and nodC genes sequences. PMID:26496493

  10. Aviation system capacity improvements through technology

    NASA Technical Reports Server (NTRS)

    Harvey, W. Don

    1995-01-01

    A study was conducted with the primary objective of determining the impact of technology on capacity improvements in the U.S. air transportation system and, consequently, to assess the areas where NASA's expertise and technical contributions would be the most beneficial. The outlook of the study is considered both near- and long-term (5 to 25 years). The approach was that of actively working with the Massachusetts Institute of Technology (MIT) Flight Transportation Laboratory and included interactions with 'users' outside of both agencies as well as with organizations within. This report includes an overall survey of what are believed to be the causes of the capacity problems, ongoing work with the Federal Aviation Administration (FAA) to alleviate the problems, and identifies improvements in technology that would increase capacity and reduce delays.

  11. Improvements in continuum modeling for biomolecular systems

    NASA Astrophysics Data System (ADS)

    Yu, Qiao; Ben-Zhuo, Lu

    2016-01-01

    Modeling of biomolecular systems plays an essential role in understanding biological processes, such as ionic flow across channels, protein modification or interaction, and cell signaling. The continuum model described by the Poisson- Boltzmann (PB)/Poisson-Nernst-Planck (PNP) equations has made great contributions towards simulation of these processes. However, the model has shortcomings in its commonly used form and cannot capture (or cannot accurately capture) some important physical properties of the biological systems. Considerable efforts have been made to improve the continuum model to account for discrete particle interactions and to make progress in numerical methods to provide accurate and efficient simulations. This review will summarize recent main improvements in continuum modeling for biomolecular systems, with focus on the size-modified models, the coupling of the classical density functional theory and the PNP equations, the coupling of polar and nonpolar interactions, and numerical progress. Project supported by the National Natural Science Foundation of China (Grant No. 91230106) and the Chinese Academy of Sciences Program for Cross & Cooperative Team of the Science & Technology Innovation.

  12. Symbiote transmission and maintenance of extra-genomic associations

    PubMed Central

    Fitzpatrick, Benjamin M.

    2014-01-01

    Symbiotes can be transmitted from parents to offspring or horizontally from unrelated hosts or the environment. A key question is whether symbiote transmission is similar enough to Mendelian gene transmission to generate and maintain coevolutionary associations between host and symbiote genes. Recent papers come to opposite conclusions, with some suggesting that any horizontal transmission eliminates genetic association. These studies are hard to compare owing to arbitrary differences in modeling approach, parameter values, and assumptions about selection. I show that associations between host and symbiote genes (extra-genomic associations) can be described by the same dynamic model as conventional linkage disequilibria between genes in the same genome. Thus, covariance between host and symbiote genomes depends on population history, geographic structure, selection, and co-transmission rate, just as covariance between genes within a genome. The conclusion that horizontal transmission rapidly erodes extra-genomic associations is equivalent to the conclusion that recombination rapidly erodes associations between genes within a genome. The conclusion is correct in the absence of population structure or selection. However, population structure can maintain spatial associations between host and symbiote traits, and non-additive selection (interspecific epistasis) can generate covariances between host and symbiote genotypes. These results can also be applied to cultural or other non-genetic traits. This work contributes to a growing consensus that genomic, symbiotic, and gene-culture evolution can be analyzed under a common theoretical framework. In terms of coevolutionary potential, symbiotes can be viewed as lying on a continuum between the intimacy of genes and the indifference of casually co-occurring species. PMID:24605109

  13. Symbiote transmission and maintenance of extra-genomic associations.

    PubMed

    Fitzpatrick, Benjamin M

    2014-01-01

    Symbiotes can be transmitted from parents to offspring or horizontally from unrelated hosts or the environment. A key question is whether symbiote transmission is similar enough to Mendelian gene transmission to generate and maintain coevolutionary associations between host and symbiote genes. Recent papers come to opposite conclusions, with some suggesting that any horizontal transmission eliminates genetic association. These studies are hard to compare owing to arbitrary differences in modeling approach, parameter values, and assumptions about selection. I show that associations between host and symbiote genes (extra-genomic associations) can be described by the same dynamic model as conventional linkage disequilibria between genes in the same genome. Thus, covariance between host and symbiote genomes depends on population history, geographic structure, selection, and co-transmission rate, just as covariance between genes within a genome. The conclusion that horizontal transmission rapidly erodes extra-genomic associations is equivalent to the conclusion that recombination rapidly erodes associations between genes within a genome. The conclusion is correct in the absence of population structure or selection. However, population structure can maintain spatial associations between host and symbiote traits, and non-additive selection (interspecific epistasis) can generate covariances between host and symbiote genotypes. These results can also be applied to cultural or other non-genetic traits. This work contributes to a growing consensus that genomic, symbiotic, and gene-culture evolution can be analyzed under a common theoretical framework. In terms of coevolutionary potential, symbiotes can be viewed as lying on a continuum between the intimacy of genes and the indifference of casually co-occurring species. PMID:24605109

  14. Symbiotic Stars on Asiago Archive Plates

    NASA Astrophysics Data System (ADS)

    Jurdana-Šepić, Rajka; Munari, Ulisse

    2010-01-01

    The Asiago photographic archive has been searched for plates containing the symbiotic stars AS 210, AS 327, AX Per, BF Cyg, CI Cyg, DT Ser, EG And, GH Gem, Hen 2-442, Hen 3-1591, HM Sge, MaC 1-17, NSV 11776, Pe 2-16, Pt 1, PU Vul, RS Oph, T CrB, UV Aur, V1016 Cyg, V1329 Cyg, V352 Aql, V4018 Sgr, Wray 15-1470, and Z And. A total of 1617 good-quality plates imaging the program stars have been found and their brightness has been estimated using the Henden & Munari UBVRCIC local photometric sequences. The results for the objects with most abundant measurements are discussed.

  15. The Role of Symbiotic Nitrogen Fixation in Sustainable Production of Biofuels

    PubMed Central

    Biswas, Bandana; Gresshoff, Peter M.

    2014-01-01

    With the ever-increasing population of the world (expected to reach 9.6 billion by 2050), and altered life style, comes an increased demand for food, fuel and fiber. However, scarcity of land, water and energy accompanied by climate change means that to produce enough to meet the demands is getting increasingly challenging. Today we must use every avenue from science and technology available to address these challenges. The natural process of symbiotic nitrogen fixation, whereby plants such as legumes fix atmospheric nitrogen gas to ammonia, usable by plants can have a substantial impact as it is found in nature, has low environmental and economic costs and is broadly established. Here we look at the importance of symbiotic nitrogen fixation in the production of biofuel feedstocks; how this process can address major challenges, how improving nitrogen fixation is essential, and what we can do about it. PMID:24786096

  16. The role of symbiotic nitrogen fixation in sustainable production of biofuels.

    PubMed

    Biswas, Bandana; Gresshoff, Peter M

    2014-01-01

    With the ever-increasing population of the world (expected to reach 9.6 billion by 2050), and altered life style, comes an increased demand for food, fuel and fiber. However, scarcity of land, water and energy accompanied by climate change means that to produce enough to meet the demands is getting increasingly challenging. Today we must use every avenue from science and technology available to address these challenges. The natural process of symbiotic nitrogen fixation, whereby plants such as legumes fix atmospheric nitrogen gas to ammonia, usable by plants can have a substantial impact as it is found in nature, has low environmental and economic costs and is broadly established. Here we look at the importance of symbiotic nitrogen fixation in the production of biofuel feedstocks; how this process can address major challenges, how improving nitrogen fixation is essential, and what we can do about it. PMID:24786096

  17. Three Fundamental Periods in an 87 Year Light Curve of the Symbiotic Star MWC 560

    NASA Astrophysics Data System (ADS)

    Leibowitz, Elia M.; Formiggini, Liliana

    2015-08-01

    We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

  18. SLAC modulator system improvements and reliability results

    SciTech Connect

    Donaldson, A.R.

    1998-06-01

    In 1995, an improvement project was completed on the 244 klystron modulators in the linear accelerator. The modulator system has been previously described. This article offers project details and their resulting effect on modulator and component reliability. Prior to the project, the authors had collected four operating cycles (1991 through 1995) of MTTF data. In this discussion, the '91 data will be excluded since the modulators operated at 60 Hz. The five periods following the '91 run were reviewed due to the common repetition rate at 120 Hz.

  19. Surface Operations Systems Improve Airport Efficiency

    NASA Technical Reports Server (NTRS)

    2009-01-01

    With Small Business Innovation Research (SBIR) contracts from Ames Research Center, Mosaic ATM of Leesburg, Virginia created software to analyze surface operations at airports. Surface surveillance systems, which report locations every second for thousands of air and ground vehicles, generate massive amounts of data, making gathering and analyzing this information difficult. Mosaic?s Surface Operations Data Analysis and Adaptation (SODAA) tool is an off-line support tool that can analyze how well the airport surface operation is working and can help redesign procedures to improve operations. SODAA helps researchers pinpoint trends and correlations in vast amounts of recorded airport operations data.

  20. Instrumentation for Improvement of Gas Imaging Systems

    NASA Astrophysics Data System (ADS)

    Happer, William

    2002-08-01

    Funds from the AFOSR:DURIP grant F49620-01-1-0254 have been used to purchase three major pieces of equipment: (1) a nuclear magnetic resonance-spectrometer; system for studies of the basic-physics of hyperpolarized.Xe-129 and He-3 gases; (2) a 9.4 T superconducting magnet with a 3 inch room temperature bore; (3) a Verdi diode-pumped Nd:YAG laser to replace the very expensive argon ion laser we have traditionally used for pumping our Ti:sapphire tunable laser. This new equipment has greatly improved the research productivity of our laboratory.

  1. An improved drone tracking control system transponder

    NASA Astrophysics Data System (ADS)

    Miller, James J.; Tannenholz, Philip H.

    A small, compact, and inexpensive method of achieving frequency stability of a solid state LO to +/- 1 MHz in the MD700C-1 drone tracking and control system C-band command and control transponder is described. The methodology for realizing improved RF rejection, local oscillator stability, automatic gain control, and power supply efficiency is discussed. A switching mode regulator and a nonsaturating power supply were designed to operate at 80 percent efficiency to reduce power consumption and heat while operating over a wide voltage range.

  2. Improved orbiter waste collection system study

    NASA Technical Reports Server (NTRS)

    Bastin, P. H.

    1984-01-01

    Design concepts for improved fecal waste collection both on the space shuttle orbiter and as a precursor for the space station are discussed. Inflight usage problems associated with the existing orbiter waste collection subsystem are considered. A basis was sought for the selection of an optimum waste collection system concept which may ultimately result in the development of an orbiter flight test article for concept verification and subsequent production of new flight hardware. Two concepts were selected for orbiter and are shown in detail. Additionally, one concept selected for application to the space station is presented.

  3. Computer symbiosis: Emergence of symbiotic behavior through evolution

    SciTech Connect

    Ikegami, Takashi; Kaneko, Kunihiko

    1989-01-01

    Symbiosis is altruistic cooperation between distinct species. It is one of the most effective evolutionary processes, but its dynamics are not well understood as yet. A simple model of symbiosis is introduced, where we consider interactions between hosts and parasites and also mutations of hosts and parasites. It is found that a symbiotic state emerges for a suitable range of mutation rates. The symbiotic state is not static, but dynamically oscillates. Harmful parasites violating symbiosis appear periodically, but are rapidly extinguished by hosts and other parasites, and the symbiotic state is recovered. The emergence of ''Tit for Tat'' strategy to maintain symbiosis is discussed. 4 figs.

  4. AG Pegasi - now a classical symbiotic star in outburst?

    NASA Astrophysics Data System (ADS)

    Tomov, T. V.; Stoyanov, K. A.; Zamanov, R. K.

    2016-08-01

    Optical spectroscopy study of the recent AG Peg outburst observed during the second half of 2015 is presented. Considerable variations of the intensity and the shape of the spectral features as well as the changes of the hot component parameters, caused by the outburst, are discussed and certain similarities between the outburst of AG Peg and the outburst of a classical symbiotic stars are shown. It seems that after the end of the symbiotic nova phase, AG Peg became a member of the classical symbiotic stars group.

  5. Advanced kick detection systems improve HPHT operations

    SciTech Connect

    Harris, T.W.R.; Hendriks, P.; Surewaard, J.H.G.

    1995-09-01

    Many high-pressure, high-temperature (HPHT) wells are often characterized by the small margins that can exist between pore pressure and formation strength. Therefore, it is not surprising that kicks are far more likely to occur in HPHT wells and that a greater risk of internal blowout exists. The development and application of advanced kick detection systems for HPHT wells can help manage risks and improve drilling efficiency. Such systems enable earlier well shut-in, minimizing both the influx volume and the subsequent well bore pressures. This in turn lowers the risk, time and cost required for well control operations. Carefully considered application of these systems can also justify favorable economic benefits by optimization of the HPHT preliminary casing design. Minimizing kick volume can be important for the critical HPHT hole sections, where a reduced operating margin between pore pressure and fracture gradient exists, defining small design kick tolerance limits to permit safe drilling ahead to reach specified objectives. Kick detection for HPHT wells equivalent to less than 5 bbl of gas influx are often necessary to adequately minimize the risk of internal blowout and obtain the same levels of safety which are applied to conventional wells. This paper reviews these systems for both on-shore and off-shore operations.

  6. Outburst Activity Driven by Evolved Pulsating Star in the Symbiotic Binary AG Dra

    NASA Astrophysics Data System (ADS)

    Gális, R.; Hric, L.; Leedjärv, L.

    2015-12-01

    The symbiotic system AG Dra regularly undergoes quiescent and active stages which consist of the series of individual outbursts. The period analysis of new and historical photometric data, as well as radial velocities, confirmed the presence of the two periods. The longer one around ≈ 550 d is related to the orbital motion and the shorter one ≈355 d could be due to pulsation of the cool component of AG Dra.

  7. Biochemical Approaches to Improved Nitrogen Fixation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving symbiotic nitrogen fixation by legumes has emerged again as an important topic on the world scene due to the energy crisis and lack of access to nitrogen fertilizer in developing countries. We have taken a biochemical genomics approach to improving symbiotic nitrogen fixation in legumes. L...

  8. A systems approach to understanding and improving health systems.

    PubMed

    Erazo, Álvaro

    2015-09-01

    Health systems face the challenge of helping to improve health conditions. They occupy a priority place in middle- and lower-income countries, since the absence or fragility of health systems adversely impacts expected health outcomes. Thus, due to the direct relationship between programs and systems, the absence or weakness of either will result in a consequent deficiency in public health and the very execution of the programs. In the same vein, weakened health systems are one of the main bottlenecks to attaining the Millennium Development Goals. Systems thinking is one of the "four revolutions in progress" that are helping to transform health and health care systems. Within that framework, this article identifies conceptual and operational elements of systems applicable to health systems that contribute to overcoming the obstacles and inertia that hinder health activities and outcomes. It discusses relevant concepts characteristic of systems thinking, such as structural variables and dynamic complexity, the relationship between programs and health systems, and the monitoring and evaluation function, together with the role of innovation and systems integration as high-priority elements. This will aid in the development of designs that also stress the context of the components that guide management, identifying processes and outcomes in a health management continuum. PMID:26758004

  9. Towards the minimal nitrogen-fixing symbiotic genome.

    PubMed

    Sanjuán, Juan

    2016-09-01

    diCenzo and coworkers have reverse engineered a rhizobium into a non-nitrogen fixer, creating a genomic platform for gain-of-function genetics studies, which should aid to identify the minimal nitrogen fixing symbiotic genome. PMID:27188818

  10. LES ARM Symbiotic Simulation and Observation (LASSO) Implementation Strategy

    SciTech Connect

    Gustafson Jr., WI; Vogelmann, AM

    2015-09-01

    This document illustrates the design of the Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) workflow to provide a routine, high-resolution modeling capability to augment the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s high-density observations. LASSO will create a powerful new capability for furthering ARM’s mission to advance understanding of cloud, radiation, aerosol, and land-surface processes. The combined observational and modeling elements will enable a new level of scientific inquiry by connecting processes and context to observations and providing needed statistics for details that cannot be measured. The result will be improved process understanding that facilitates concomitant improvements in climate model parameterizations. The initial LASSO implementation will be for ARM’s Southern Great Plains site in Oklahoma and will focus on shallow convection, which is poorly simulated by climate models due in part to clouds’ typically small spatial scale compared to model grid spacing, and because the convection involves complicated interactions of microphysical and boundary layer processes.

  11. Symbiotic relationship of thiothrix spp. with An echinoderm

    PubMed

    Brigmon; De Ridder C

    1998-09-01

    Immunoassay procedures were used to investigate the symbiotic relationship of Thiothrix spp. in the intestinal cecum of the spatangoid species Echinocardium cordatum. Thiothrix spp. were identified in nodule samples from E. cordatum digestive tubes based on microscopic examination, enzyme-linked immunosorbent assay, and indirect immunofluorescence. Thiothrix spp. protein made up as much as 84% of the total protein content of the nodules. This is the first identification of Thiothrix spp. internally symbiotic with marine invertebrates. PMID:9726902

  12. Symbiotic Relationship of Thiothrix spp. with an Echinoderm†

    PubMed Central

    Brigmon, Robin L.; De Ridder, Chantal

    1998-01-01

    Immunoassay procedures were used to investigate the symbiotic relationship of Thiothrix spp. in the intestinal cecum of the spatangoid species Echinocardium cordatum. Thiothrix spp. were identified in nodule samples from E. cordatum digestive tubes based on microscopic examination, enzyme-linked immunosorbent assay, and indirect immunofluorescence. Thiothrix spp. protein made up as much as 84% of the total protein content of the nodules. This is the first identification of Thiothrix spp. internally symbiotic with marine invertebrates. PMID:9726902

  13. Symbiotic lactobacilli stimulate gut epithelial proliferation via Nox-mediated generation of reactive oxygen species

    PubMed Central

    Jones, Rheinallt M; Luo, Liping; Ardita, Courtney S; Richardson, Arena N; Kwon, Young Man; Mercante, Jeffrey W; Alam, Ashfaqul; Gates, Cymone L; Wu, Huixia; Swanson, Phillip A; Lambeth, J David; Denning, Patricia W; Neish, Andrew S

    2013-01-01

    The resident prokaryotic microbiota of the metazoan gut elicits profound effects on the growth and development of the intestine. However, the molecular mechanisms of symbiotic prokaryotic–eukaryotic cross-talk in the gut are largely unknown. It is increasingly recognized that physiologically generated reactive oxygen species (ROS) function as signalling secondary messengers that influence cellular proliferation and differentiation in a variety of biological systems. Here, we report that commensal bacteria, particularly members of the genus Lactobacillus, can stimulate NADPH oxidase 1 (Nox1)-dependent ROS generation and consequent cellular proliferation in intestinal stem cells upon initial ingestion into the murine or Drosophila intestine. Our data identify and highlight a highly conserved mechanism that symbiotic microorganisms utilize in eukaryotic growth and development. Additionally, the work suggests that specific redox-mediated functions may be assigned to specific bacterial taxa and may contribute to the identification of microbes with probiotic potential. PMID:24141879

  14. Sensitive response of a model of symbiotic ecosystem to seasonal periodic drive

    SciTech Connect

    Rekker, A.; Lumi, N.; Mankin, R.

    2014-11-12

    A symbiotic ecosysytem (metapopulation) is studied by means of the stochastic Lotka-Volterra model with generalized Verhulst self-regulation. The effect of variable environment on the carrying capacities of populations is taken into account as an asymmetric dichotomous noise and as a deterministic periodic stimulus. In the framework of the mean-field theory an explicit self-consistency equation for the system in the long-time limit is presented. Also, expressions for the probability distribution and for the moments of the population size are found. In certain cases the mean population size exhibits large oscillations in time, even if the amplitude of the seasonal environmental drive is small. Particularly, it is shown that the occurrence of large oscillations of the mean population size can be controlled by noise parameters (such as amplitude and correlation time) and by the coupling strength of the symbiotic interaction between species.

  15. Sensitive response of a model of symbiotic ecosystem to seasonal periodic drive

    NASA Astrophysics Data System (ADS)

    Rekker, A.; Lumi, N.; Mankin, R.

    2014-11-01

    A symbiotic ecosysytem (metapopulation) is studied by means of the stochastic Lotka-Volterra model with generalized Verhulst self-regulation. The effect of variable environment on the carrying capacities of populations is taken into account as an asymmetric dichotomous noise and as a deterministic periodic stimulus. In the framework of the mean-field theory an explicit self-consistency equation for the system in the long-time limit is presented. Also, expressions for the probability distribution and for the moments of the population size are found. In certain cases the mean population size exhibits large oscillations in time, even if the amplitude of the seasonal environmental drive is small. Particularly, it is shown that the occurrence of large oscillations of the mean population size can be controlled by noise parameters (such as amplitude and correlation time) and by the coupling strength of the symbiotic interaction between species.

  16. Improving Steam System Performance: A Sourcebook for Industry, Second Edition

    SciTech Connect

    2012-02-23

    This sourcebook is designed to provide steam system users with a reference that describes the basic steam system components, outlines opportunities for energy and performance improvements, and discusses the benefits of a systems approach in identifying and implementing these improvement opportunities. The sourcebook is divided into three main sections: steam system basics, performance improvement opportunities, and where to find help.

  17. Characterizing and Improving Distributed Intrusion Detection Systems.

    SciTech Connect

    Hurd, Steven A.; Proebstel, Elliot P.

    2007-11-01

    Due to ever-increasing quantities of information traversing networks, network administrators are developing greater reliance upon statistically sampled packet information as the source for their intrusion detection systems (IDS). Our research is aimed at understanding IDS performance when statistical packet sampling is used. Using the Snort IDS and a variety of data sets, we compared IDS results when an entire data set is used to the results when a statistically sampled subset of the data set is used. Generally speaking, IDS performance with statistically sampled information was shown to drop considerably even under fairly high sampling rates (such as 1:5). Characterizing and Improving Distributed Intrusion Detection Systems4AcknowledgementsThe authors wish to extend our gratitude to Matt Bishop and Chen-Nee Chuah of UC Davis for their guidance and support on this work. Our thanks are also extended to Jianning Mai of UC Davis and Tao Ye of Sprint Advanced Technology Labs for their generous assistance.We would also like to acknowledge our dataset sources, CRAWDAD and CAIDA, without which this work would not have been possible. Support for OC48 data collection is provided by DARPA, NSF, DHS, Cisco and CAIDA members.

  18. Improved Refractories for IGCC Power Systems

    SciTech Connect

    Dogan, Cynthia P.; Kwong, Kyei-Sing; Bennett, James P.; Chinn, Richard E.; Dahlin, Cheryl L.

    2002-01-01

    The gasification of coal, petroleum residuals, and biomass provides the opportunity to produce energy more efficiently, and with significantly less environmental impact, than more-conventional combustion-based processes. In addition, the synthesis gas that is the product of the gasification process offers the gasifier operator the option of ''polygeneration'', i.e., the production of alternative products instead of power should it be economically favorable to do so. Because of these advantages, gasification is a key element in the U.S. Department of Energy?s Vision 21 power system. However, issues with both the reliability and the economics of gasifier operation will have to be resolved before gasification will be widely adopted by the power industry. Central to both increased reliability and economics is the development of materials with longer service lives in gasifier systems that can provide extended periods of continuous gasifier operation. The focus of the Advanced Refractories for Gasification project at the Albany Research Center is to develop improved materials capable of withstanding the harsh, high-temperature environment created by the gasification reaction, and includes both the refractory lining that insulates the slagging gasifier, as well as the thermocouple assemblies that are utilized to monitor gasifier operating temperatures. Current generation refractory liners in slagging gasifiers are typically replaced every 10 to 18 months, at costs ranging up to $2,000,000. Compounding materials and installation costs are the lost-opportunity costs for the three to four weeks that the gasifier is off-line for the refractory exchange. Current generation thermocouple devices rarely survive the gasifier start-up process, leaving the operator with no real means of temperature measurement during gasifier operation. As a result, the goals of this project include the development of a refractory liner with a service life at least double that of current generation

  19. Improving robustness of speech recognition systems

    NASA Astrophysics Data System (ADS)

    Mitra, Vikramjit

    2010-11-01

    speech databases: X-ray microbeam and Aurora-2 were annotated, where the former was used to train a TV-estimator and the latter was used to train a Dynamic Bayesian Network (DBN) based ASR architecture. The DBN architecture used two sets of observation: (a) acoustic features in the form of mel-frequency cepstral coefficients (MFCCs) and (b) TVs (estimated from the acoustic speech signal). In this setup the articulatory gestures were modeled as hidden random variables, hence eliminating the necessity for explicit gesture recognition. Word recognition results using the DBN architecture indicate that articulatory representations not only can help to account for coarticulatory variations but can also significantly improve the noise robustness of ASR system.

  20. SINFAC - SYSTEMS IMPROVED NUMERICAL FLUIDS ANALYSIS CODE

    NASA Technical Reports Server (NTRS)

    Costello, F. A.

    1994-01-01

    The Systems Improved Numerical Fluids Analysis Code, SINFAC, consists of additional routines added to the April 1983 revision of SINDA, a general thermal analyzer program. The purpose of the additional routines is to allow for the modeling of active heat transfer loops. The modeler can simulate the steady-state and pseudo-transient operations of 16 different heat transfer loop components including radiators, evaporators, condensers, mechanical pumps, reservoirs and many types of valves and fittings. In addition, the program contains a property analysis routine that can be used to compute the thermodynamic properties of 20 different refrigerants. SINFAC can simulate the response to transient boundary conditions. SINFAC was first developed as a method for computing the steady-state performance of two phase systems. It was then modified using CNFRWD, SINDA's explicit time-integration scheme, to accommodate transient thermal models. However, SINFAC cannot simulate pressure drops due to time-dependent fluid acceleration, transient boil-out, or transient fill-up, except in the accumulator. SINFAC also requires the user to be familiar with SINDA. The solution procedure used by SINFAC is similar to that which an engineer would use to solve a system manually. The solution to a system requires the determination of all of the outlet conditions of each component such as the flow rate, pressure, and enthalpy. To obtain these values, the user first estimates the inlet conditions to the first component of the system, then computes the outlet conditions from the data supplied by the manufacturer of the first component. The user then estimates the temperature at the outlet of the third component and computes the corresponding flow resistance of the second component. With the flow resistance of the second component, the user computes the conditions down stream, namely the inlet conditions of the third. The computations follow for the rest of the system, back to the first component

  1. Symbiotic two-species contact process.

    PubMed

    de Oliveira, Marcelo Martins; Dos Santos, Renato Vieira; Dickman, Ronald

    2012-07-01

    We study a contact process (CP) with two species that interact in a symbiotic manner. In our model, each site of a lattice may be vacant or host individuals of species A and/or B; multiple occupancy by the same species is prohibited. Symbiosis is represented by a reduced death rate μ<1 for individuals at sites with both species present. Otherwise, the dynamics is that of the basic CP, with creation (at vacant neighbor sites) at rate λ and death of (isolated) individuals at a rate of unity. Mean-field theory and Monte Carlo simulation show that the critical creation rate λ(c)(μ) is a decreasing function of μ, even though a single-species population must go extinct for λ<λ(c) (1), the critical point of the basic CP. Extensive simulations yield results for critical behavior that are compatible with the directed percolation (DP) universality class, but with unusually strong corrections to scaling. A field-theoretic argument supports the conclusion of DP critical behavior. We obtain similar results for a CP with creation at second-neighbor sites and enhanced survival at first neighbors in the form of an annihilation rate that decreases with the number of occupied first neighbors. PMID:23005382

  2. Symbiotic two-species contact process

    NASA Astrophysics Data System (ADS)

    de Oliveira, Marcelo Martins; Dos Santos, Renato Vieira; Dickman, Ronald

    2012-07-01

    We study a contact process (CP) with two species that interact in a symbiotic manner. In our model, each site of a lattice may be vacant or host individuals of species A and/or B; multiple occupancy by the same species is prohibited. Symbiosis is represented by a reduced death rate μ<1 for individuals at sites with both species present. Otherwise, the dynamics is that of the basic CP, with creation (at vacant neighbor sites) at rate λ and death of (isolated) individuals at a rate of unity. Mean-field theory and Monte Carlo simulation show that the critical creation rate λc(μ) is a decreasing function of μ, even though a single-species population must go extinct for λ<λc(1), the critical point of the basic CP. Extensive simulations yield results for critical behavior that are compatible with the directed percolation (DP) universality class, but with unusually strong corrections to scaling. A field-theoretic argument supports the conclusion of DP critical behavior. We obtain similar results for a CP with creation at second-neighbor sites and enhanced survival at first neighbors in the form of an annihilation rate that decreases with the number of occupied first neighbors.

  3. Intracellular pH of symbiotic dinoflagellates

    NASA Astrophysics Data System (ADS)

    Gibbin, E. M.; Davy, S. K.

    2013-09-01

    Intracellular pH (pHi) is likely to play a key role in maintaining the functional success of cnidarian-dinoflagellate symbiosis, yet until now the pHi of the symbiotic dinoflagellates (genus Symbiodinium) has never been quantified. Flow cytometry was used in conjunction with the ratiometric fluorescent dye BCECF to monitor changes in pHi over a daily light/dark cycle. The pHi of Symbiodinium type B1 freshly isolated from the model sea anemone Aiptasia pulchella was 7.25 ± 0.01 (mean ± SE) in the light and 7.10 ± 0.02 in the dark. A comparable effect of irradiance was seen across a variety of cultured Symbiodinium genotypes (types A1, B1, E1, E2, F1, and F5) which varied between pHi 7.21-7.39 in the light and 7.06-7.14 in the dark. Of note, there was a significant genotypic difference in pHi, irrespective of irradiance.

  4. Superfinished Surfaces for Power Transfer Systems Improvement

    NASA Technical Reports Server (NTRS)

    Niskanen, Paul; Manesh, Ali; Warren, Alford; Krantz, Timothy

    2002-01-01

    The continuous demands for high performance and lightweight power train systems resulted in requirements for higher power density gearing systems. However, increasing the load bearing capacity of the gear teeth, without increasing size, places stringent requirements upon metallurgy, dimensional control, and surface finish of the final products. In order to operate the mating parts near the upper bounds of their theoretical design envelope, manufacturing processes are required that are capable of improving the fatigue life and load bearing capacity of precision parts, while producing the required geometric accuracy. Results of the recent experimental studies indicate that the super finishing process is able to achieve these goals. This paper will review the results of our continuing evaluation of the super finish process as applied to aerospace gearing. Two separate evaluations were performed on gears to examine the effects of super finishing on resistance to both pitting and contact fatigue. For the reported experiments, both conventional and super finished test gears were simultaneously manufactured using the same process and the same heat lot of materials. This paper will also provide a brief description of the manufacturing technology used to achieve the results and will compare the results with other published data. In addition, this paper presents a couple of off-the-shelf manufacturing technologies that have been successfully used to super finish test specimens and will provide a glimpse of other emerging super finishing technologies. This is a US Army Manufacturing Technology project. The project was sponsored by the Aviation and Missiles Command (AMCOM) and was being managed and conducted by IIT Research Institute.

  5. Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus

    PubMed Central

    Becker, Matthew H.; Walke, Jenifer B.; Cikanek, Shawna; Savage, Anna E.; Mattheus, Nichole; Santiago, Celina N.; Minbiole, Kevin P. C.; Harris, Reid N.; Belden, Lisa K.; Gratwicke, Brian

    2015-01-01

    Symbiotic microbes can dramatically impact host health and fitness, and recent research in a diversity of systems suggests that different symbiont community structures may result in distinct outcomes for the host. In amphibians, some symbiotic skin bacteria produce metabolites that inhibit the growth of Batrachochytrium dendrobatidis (Bd), a cutaneous fungal pathogen that has caused many amphibian population declines and extinctions. Treatment with beneficial bacteria (probiotics) prevents Bd infection in some amphibian species and creates optimism for conservation of species that are highly susceptible to chytridiomycosis, the disease caused by Bd. In a laboratory experiment, we used Bd-inhibitory bacteria from Bd-tolerant Panamanian amphibians in a probiotic development trial with Panamanian golden frogs, Atelopus zeteki, a species currently surviving only in captive assurance colonies. Approximately 30% of infected golden frogs survived Bd exposure by either clearing infection or maintaining low Bd loads, but this was not associated with probiotic treatment. Survival was instead related to initial composition of the skin bacterial community and metabolites present on the skin. These results suggest a strong link between the structure of these symbiotic microbial communities and amphibian host health in the face of Bd exposure and also suggest a new approach for developing amphibian probiotics. PMID:25788591

  6. Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus.

    PubMed

    Becker, Matthew H; Walke, Jenifer B; Cikanek, Shawna; Savage, Anna E; Mattheus, Nichole; Santiago, Celina N; Minbiole, Kevin P C; Harris, Reid N; Belden, Lisa K; Gratwicke, Brian

    2015-04-22

    Symbiotic microbes can dramatically impact host health and fitness, and recent research in a diversity of systems suggests that different symbiont community structures may result in distinct outcomes for the host. In amphibians, some symbiotic skin bacteria produce metabolites that inhibit the growth of Batrachochytrium dendrobatidis (Bd), a cutaneous fungal pathogen that has caused many amphibian population declines and extinctions. Treatment with beneficial bacteria (probiotics) prevents Bd infection in some amphibian species and creates optimism for conservation of species that are highly susceptible to chytridiomycosis, the disease caused by Bd. In a laboratory experiment, we used Bd-inhibitory bacteria from Bd-tolerant Panamanian amphibians in a probiotic development trial with Panamanian golden frogs, Atelopus zeteki, a species currently surviving only in captive assurance colonies. Approximately 30% of infected golden frogs survived Bd exposure by either clearing infection or maintaining low Bd loads, but this was not associated with probiotic treatment. Survival was instead related to initial composition of the skin bacterial community and metabolites present on the skin. These results suggest a strong link between the structure of these symbiotic microbial communities and amphibian host health in the face of Bd exposure and also suggest a new approach for developing amphibian probiotics. PMID:25788591

  7. Genomic characterization of symbiotic mycoplasmas from the stomach of deep-sea isopod bathynomus sp.

    PubMed

    Wang, Yong; Huang, Jiao-Mei; Wang, Shao-Lu; Gao, Zhao-Ming; Zhang, Ai-Qun; Danchin, Antoine; He, Li-Sheng

    2016-09-01

    Deep-sea isopod scavengers such as Bathynomus sp. are able to live in nutrient-poor environments, which is likely attributable to the presence of symbiotic microbes in their stomach. In this study we recovered two draft genomes of mycoplasmas, Bg1 and Bg2, from the metagenomes of the stomach contents and stomach sac of a Bathynomus sp. sample from the South China Sea (depth of 898 m). Phylogenetic trees revealed a considerable genetic distance to other mycoplasma species for Bg1 and Bg2. Compared with terrestrial symbiotic mycoplasmas, the Bg1 and Bg2 genomes were enriched with genes encoding phosphoenolpyruvate-dependent phosphotransferase systems (PTSs) and sodium-driven symporters responsible for the uptake of sugars, amino acids and other carbohydrates. The genome of mycoplasma Bg1 contained sialic acid lyase and transporter genes, potentially enabling the bacteria to attach to the stomach sac and obtain organic carbons from various cell walls. Both of the mycoplasma genomes contained multiple copies of genes related to proteolysis and oligosaccharide degradation, which may help the host survive in low-nutrient conditions. The discovery of the different types of mycoplasma bacteria in the stomach of this deep-sea isopod affords insights into symbiotic model of deep-sea animals and genomic plasticity of mycoplasma bacteria. PMID:27312602

  8. A role for the mevalonate pathway in early plant symbiotic signaling

    PubMed Central

    Venkateshwaran, Muthusubramanian; Jayaraman, Dhileepkumar; Chabaud, Mireille; Genre, Andrea; Balloon, Allison J.; Maeda, Junko; Forshey, Kari; den Os, Désirée; Kwiecien, Nicholas W.; Coon, Joshua J.; Barker, David G.; Ané, Jean-Michel

    2015-01-01

    Rhizobia and arbuscular mycorrhizal fungi produce signals that are perceived by host legume receptors at the plasma membrane and trigger sustained oscillations of the nuclear and perinuclear Ca2+ concentration (Ca2+ spiking), which in turn leads to gene expression and downstream symbiotic responses. The activation of Ca2+ spiking requires the plasma membrane-localized receptor-like kinase Does not Make Infections 2 (DMI2) as well as the nuclear cation channel DMI1. A key enzyme regulating the mevalonate (MVA) pathway, 3-Hydroxy-3-Methylglutaryl CoA Reductase 1 (HMGR1), interacts with DMI2 and is required for the legume–rhizobium symbiosis. Here, we show that HMGR1 is required to initiate Ca2+ spiking and symbiotic gene expression in Medicago truncatula roots in response to rhizobial and arbuscular mycorrhizal fungal signals. Furthermore, MVA, the direct product of HMGR1 activity, is sufficient to induce nuclear-associated Ca2+ spiking and symbiotic gene expression in both wild-type plants and dmi2 mutants, but interestingly not in dmi1 mutants. Finally, MVA induced Ca2+ spiking in Human Embryonic Kidney 293 cells expressing DMI1. This demonstrates that the nuclear cation channel DMI1 is sufficient to support MVA-induced Ca2+ spiking in this heterologous system. PMID:26199419

  9. Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes.

    PubMed

    Mus, Florence; Crook, Matthew B; Garcia, Kevin; Garcia Costas, Amaya; Geddes, Barney A; Kouri, Evangelia D; Paramasivan, Ponraj; Ryu, Min-Hyung; Oldroyd, Giles E D; Poole, Philip S; Udvardi, Michael K; Voigt, Christopher A; Ané, Jean-Michel; Peters, John W

    2016-07-01

    Access to fixed or available forms of nitrogen limits the productivity of crop plants and thus food production. Nitrogenous fertilizer production currently represents a significant expense for the efficient growth of various crops in the developed world. There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers in agriculture in the developed world and in developing countries, and there is significant interest in research on biological nitrogen fixation and prospects for increasing its importance in an agricultural setting. Biological nitrogen fixation is the conversion of atmospheric N2 to NH3, a form that can be used by plants. However, the process is restricted to bacteria and archaea and does not occur in eukaryotes. Symbiotic nitrogen fixation is part of a mutualistic relationship in which plants provide a niche and fixed carbon to bacteria in exchange for fixed nitrogen. This process is restricted mainly to legumes in agricultural systems, and there is considerable interest in exploring whether similar symbioses can be developed in nonlegumes, which produce the bulk of human food. We are at a juncture at which the fundamental understanding of biological nitrogen fixation has matured to a level that we can think about engineering symbiotic relationships using synthetic biology approaches. This minireview highlights the fundamental advances in our understanding of biological nitrogen fixation in the context of a blueprint for expanding symbiotic nitrogen fixation to a greater diversity of crop plants through synthetic biology. PMID:27084023

  10. Symbiotic Nitrogen Fixation and the Challenges to Its Extension to Nonlegumes

    PubMed Central

    Mus, Florence; Crook, Matthew B.; Garcia, Kevin; Garcia Costas, Amaya; Geddes, Barney A.; Kouri, Evangelia D.; Paramasivan, Ponraj; Ryu, Min-Hyung; Oldroyd, Giles E. D.; Poole, Philip S.; Udvardi, Michael K.; Voigt, Christopher A.

    2016-01-01

    Access to fixed or available forms of nitrogen limits the productivity of crop plants and thus food production. Nitrogenous fertilizer production currently represents a significant expense for the efficient growth of various crops in the developed world. There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers in agriculture in the developed world and in developing countries, and there is significant interest in research on biological nitrogen fixation and prospects for increasing its importance in an agricultural setting. Biological nitrogen fixation is the conversion of atmospheric N2 to NH3, a form that can be used by plants. However, the process is restricted to bacteria and archaea and does not occur in eukaryotes. Symbiotic nitrogen fixation is part of a mutualistic relationship in which plants provide a niche and fixed carbon to bacteria in exchange for fixed nitrogen. This process is restricted mainly to legumes in agricultural systems, and there is considerable interest in exploring whether similar symbioses can be developed in nonlegumes, which produce the bulk of human food. We are at a juncture at which the fundamental understanding of biological nitrogen fixation has matured to a level that we can think about engineering symbiotic relationships using synthetic biology approaches. This minireview highlights the fundamental advances in our understanding of biological nitrogen fixation in the context of a blueprint for expanding symbiotic nitrogen fixation to a greater diversity of crop plants through synthetic biology. PMID:27084023

  11. Far-infrared data for symbiotic stars. II - The IRAS survey observations

    NASA Technical Reports Server (NTRS)

    Kenyon, S. J.; Fernandez-Castro, T.; Stencel, R. E.

    1988-01-01

    IRAS survey data for all known symbiotic binaries are reported. S type systems have 25 micron excesses much larger than those of single red giant stars, suggesting that these objects lose mass more rapidly than do normal giants. D type objects have far-IR colors similar to those of Mira variables, implying mass-loss rate of about 10 to the -6th solar masses/yr. The near-IR extinctions of the D types indicate that their Mira components are enshrouded in optically thick dust shells, while their hot companions lie outside the shells. If this interpretation of the data is correct, then the very red near-IR colors of D type symbiotic stars are caused by extreme amounts of dust absorption rather than dust emission. The small group of D prime objects possesses far-IR colors resembling those of compact planetary nebulae or extreme OH/IR stars. It is speculated that these binaries are not symbiotic stars at all, but contain a hot compact star and an exasymptotic branch giant which is in the process of ejecting a planetary nebula shell.

  12. Chemical abundance analysis of symbiotic giants. RW Hya, SY Mus, BX Mon, and AE Ara

    NASA Astrophysics Data System (ADS)

    Galan, C.; Mikolajewska, J.; Hinkle, K. H.; Schmidt, M. R.; Gromadzki, M.

    2014-04-01

    Symbiotic stars are the long period, binary systems of strongly interacting stars at the final stages of evolution which can be useful tool to understand the chemical evolution of the Galaxy and the formation of stellar populations. Knowledge of the chemical composition of the symbiotic giants is essential to advancing our understanding of these issues but unfortunately reliably determinations exist only in a few cases. We perform a program for detailed chemical composition analysis in over 30 symbiotic giants, based on the high resolution, near-IR spectra, obtained with Phoenix/Gemini South spectrometer. The methods of the standard LTE analysis is used to obtain photospheric abundances of CNO and elements around iron peak. Here we present results obtained for four objects: RW Hya, SY Mus, BX Mon, and AE Ara. Our analysis revealed a significantly sub-solar metallicity (Me/H ~ -0.75) for RW Hya, a slightly sub-solar metallicities (Me/H ~ 0.2-0.3) in BX Mon and AE Ara, and a near-solar metallicity in SY Mus. 12C/13C isotopic ratios are low in all cases, ranging from ~6 to ~10.

  13. Application of an improved intracardiac fibreoptic system.

    PubMed Central

    Krovetz, L J; Brenner, J I; Polanyi, M; Ostrowski, D

    1978-01-01

    An improved fibreoptic in vivo haemoreflection system has been used in over 200 patients. Continuous recording of oxygen saturation while moving the catheter permits measurement of simultaneous pressure and oxygen saturation at almost an unlimited number of sites through the right heart. The oxygen saturation can be continuously monitored and the response is sufficiently fast to permit investigation of changes in oxygen saturation during portions of the cardiac cycle. Dye dilution curves have been recorded from over 200 patients. The only blood withdrawn for the dye dilution curve was the 3 ml needed for checking the calibration of the instrument. We have found that the calibration is extremely stable. In some instances where it has been deemed impractical to obtain blood for calibration, the calibration factor for each catheter may be used. In any case, the calibration check is performed at the end of the study and does not present problems of sterility. The calibration factor may yield a correction factor which then applies uniformly to all the cardiac output values obtained during the study. Images PMID:708525

  14. On the nature of the symbiotic binary AX Persei

    NASA Technical Reports Server (NTRS)

    Mikolajewska, Joanna; Kenyon, Scott J.

    1992-01-01

    Photometric and spectroscopic observations of the symbiotic binary AX Persei are presented. This system contains a red giant that fills its tidal lobe and transfers material into an accretion disk surrounding a low-mass main-sequence star. The stellar masses - 1 solar mass for the red giant and about 0.4 solar mass for the companion - suggest AX Per is poised to enter a common envelope phase of evolution. The disk luminosity increases from L(disk) about 100 solar luminosity in quiescence to L(disk) about 5700 solar luminosity in outburst for a distance of d = 2.5 kpc. Except for visual maximum, high ionization permitted emission lines - such as He II - imply an EUV luminosity comparable to the disk luminosity. High-energy photons emitted by a hot boundary layer between the disk and central star ionize a surrounding nebula to produce this permitted line emission. High ionization forbidden lines form in an extended, shock-excited region well out of the binary's orbital plane and may be associated with mass loss from the disk.

  15. Defining Requirements for Improved Photovoltaic System Reliability

    SciTech Connect

    Maish, A.B.

    1998-12-21

    Reliable systems are an essential ingredient of any technology progressing toward commercial maturity and large-scale deployment. This paper defines reliability as meeting system fictional requirements, and then develops a framework to understand and quantify photovoltaic system reliability based on initial and ongoing costs and system value. The core elements necessary to achieve reliable PV systems are reviewed. These include appropriate system design, satisfactory component reliability, and proper installation and servicing. Reliability status, key issues, and present needs in system reliability are summarized for four application sectors.

  16. [The symbiotic microflora associated with the tegument of proteocephalidean cestodes and the intestines of their fish hosts].

    PubMed

    Korneva, Zh V; Plotnikov, A O

    2006-01-01

    The indigenous symbiotic microflora associated with the tegument of proteocephalidean cestodes and the intestines of their fish hosts has been investigated in morphological and ecological aspects. The indigenous microflora associated with the cestode tegument consists of the nannobacteria population, which was present obligatorily on the surface of tegument, and the "deep microflora". The deep microflora associates with some few species of parasites only. Each individual host-parasite micro-biocenosis includes specific indigenous symbiotic microorganisms, with the differing microfloras of host intestine and parasite. Physiology, biochemistry and/or diet of hosts apparently influence on the symbiotic microflora's structure of parasites. The least bacteria abundance and diversity of their morphotypes were observed in the parasites from baby fishes. The diversity and abundance of bacteria were increased with the fish host ageing and the formation of the definitive structure of its intestine. It is an evidence of the gradual invading of the intestinal parasites (cestodes) tegument by bacterial cells. The invading is realized on the base of the microflora that was present in the food of fish host. The symbiotic microflora has specific morphological features, can regulate the homeostasis of the cestodes and fish hosts and also can maintain equilibrium of alimentary and immune interrelations in the host-parasite system. PMID:17042276

  17. The C IV doublet ratio intensity effect in symbiotic stars

    NASA Technical Reports Server (NTRS)

    Michalitsianos, A. G.; Fahey, M.; Kafatos, M.; Viotti, R.; Cassatella, A.

    1988-01-01

    High-resolution UV spectra in the 1200-2000 wavelength range of the symbiotic variable R Aqr and its nebular jet were obtained in July 1987 with the IUE. The line profile structure of the C IV 1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II region engulfing the Mira and hot companion binary also suggest multicomponent structure with radial velocities up to about -100 km/s. The value of the doublet intensity ratio in the R Aqr H II region has been observed in other similar symbiotic stars, such as RX Pup. It is suggested that the anomalous behavior of the C IV doublet intensities may be useful for studying the spatial structure and temporal nature of winds in symbiotic stars.

  18. Symbiotic relationship of Thiothrix spp. with an echinoderm

    SciTech Connect

    Brigmon, R.L.; De Ridder, C.

    1998-09-01

    Thiothrix-like bacteria have been reported as symbionts in invertebrates from sulfide-rich habitats. Isolation of these symbiotic Thiothrix-like bacteria has failed, and the organisms have not been previously identified with certainty. The genus Thiothrix was created for ensheathed filamentous bacteria that oxidize sulfide and deposit sulfur granules internally, attach to substrates, produce gliding gonidia, and form rosettes. Immunoassay procedures were used to investigate the symbiotic relationship of Thiothrix spp. in the intestinal cecum of the spatangoid species Echinocardium cordatum. Thiothrix spp. were identified in nodule samples from E. cordatum digestive tubes based on microscopic examination, enzyme-linked immunosorbent assay, and indirect immunofluorescence. Thiothrix spp. protein made up as much as 84% of the total protein content of the nodules. This is the first identification of Thiothrix spp. internally symbiotic with marine invertebrates.

  19. Improving File System Performance by Striping

    NASA Technical Reports Server (NTRS)

    Lam, Terance L.; Kutler, Paul (Technical Monitor)

    1998-01-01

    This document discusses the performance and advantages of striped file systems on the SGI AD workstations. Performance of several striped file system configurations are compared and guidelines for optimal striping are recommended.

  20. Improved traveling wave tubes. [for ECM systems

    NASA Technical Reports Server (NTRS)

    Buck, E.

    1980-01-01

    Techniques, pioneered by NASA, which will allow substantial improvements in traveling wave tube (TWT) amplifier efficiency, are described. It is shown that using design techniques developed at the Lewis Research Center, it is possible to approximately double the efficiency of the critical amplifier TWT. Attention is given to a quick method of computing the expected improvement to an ECM TWT. The benefits of such improvements such as less input power, a smaller and lighter power supply, and easier cooling are surveyed, and it noted that it is now possible to build efficient TWT's which rather than operating at saturation, can be very linear amplifiers. Finally, a new approach to power supplies is also covered.

  1. Performance improvement integration: a whole systems approach.

    PubMed

    Page, C K

    1999-02-01

    Performance improvement integration in health care organizations is a challenge for health care leaders. Required for accreditation by the Joint Commission on Accreditation of Healthcare Organizations (Joint Commission), performance improvement (PI) can be designed as a sustainable model for performance to survive in a turbulent period. Central Baptist Hospital developed a model for PI that focused on strategy established by the leadership team, delineated responsibility through the organizational structure of shared governance, and accountability for outcomes evidenced through the organization's profitability. Such an approach integrated into the culture of the organization can produce positive financial margins, positive customer satisfaction, and commendations from the Joint Commission. PMID:9926679

  2. Milwaukee Laboratory System Improvement Program (L-SIP).

    PubMed

    Gradus, M Stephen; Bhattacharyya, Sanjib; Murphy, Amy; Becker, Julie N; Baker, Bevan K

    2013-01-01

    The Laboratory System Improvement Program (L-SIP) of the Association of Public Health Laboratories aims to improve state public health laboratory (PHL) system performance through continuous quality improvement. We successfully applied this state assessment tool to a local PHL (LPHL) system by tailoring it to reflect local system needs and created an LPHL system definition explaining how a local system differs from, yet complements, a state system. On November 18, 2010, 75 stakeholders from 40 agencies assessed the Milwaukee, Wisconsin, PHL system, capturing themes, strengths and weaknesses of the system, and scores for each of the 10 Essential Public Health Services. A Laboratory Advisory Committee analyzed assessment results to identify a strategic focus of research and workforce development and define an action plan, which is now being carried out. Milwaukee's L-SIP process is effectively improving LPHL system research and workforce development while raising community awareness of the system. PMID:23997302

  3. Milwaukee Laboratory System Improvement Program (L-SIP)

    PubMed Central

    Bhattacharyya, Sanjib; Murphy, Amy; Becker, Julie N.; Baker, Bevan K.

    2013-01-01

    The Laboratory System Improvement Program (L-SIP) of the Association of Public Health Laboratories aims to improve state public health laboratory (PHL) system performance through continuous quality improvement. We successfully applied this state assessment tool to a local PHL (LPHL) system by tailoring it to reflect local system needs and created an LPHL system definition explaining how a local system differs from, yet complements, a state system. On November 18, 2010, 75 stakeholders from 40 agencies assessed the Milwaukee, Wisconsin, PHL system, capturing themes, strengths and weaknesses of the system, and scores for each of the 10 Essential Public Health Services. A Laboratory Advisory Committee analyzed assessment results to identify a strategic focus of research and workforce development and define an action plan, which is now being carried out. Milwaukee's L-SIP process is effectively improving LPHL system research and workforce development while raising community awareness of the system. PMID:23997302

  4. Symbiotic fungal associations in 'lower' land plants.

    PubMed

    Read, D J; Ducket, J G; Francis, R; Ligron, R; Russell, A

    2000-06-29

    An analysis of the current state of knowledge of symbiotic fungal associations in 'lower' plants is provided. Three fungal phyla, the Zygomycota, Ascomycota and Basidiomycota, are involved in forming these associations, each producing a distinctive suite of structural features in well-defined groups of 'lower' plants. Among the 'lower' plants only mosses and Equisetum appear to lack one or other of these types of association. The salient features of the symbioses produced by each fungal group are described and the relationships between these associations and those formed by the same or related fungi in 'higher' plants are discussed. Particular consideration is given to the question of the extent to which root fungus associations in 'lower' plants are analogous to 'mycorrhizas' of 'higher' plants and the need for analysis of the functional attributes of these symbioses is stressed. Zygomycetous fungi colonize a wide range of extant lower land plants (hornworts, many hepatics, lycopods, Ophioglossales, Psilotales and Gleicheniaceae), where they often produce structures analogous to those seen in the vesicular-arbuscular (VA) mycorrhizas of higher plants, which are formed by members of the order Glomales. A preponderance of associations of this kind is in accordance with palaeohbotanical and molecular evidence indicating that glomalean fungi produced the archetypal symbioses with the first plants to emerge on to land. It is shown, probably for the first time, that glomalean fungi forming typical VA mycorrhiza with a higher plant (Plantago lanceolata) can colonize a thalloid liverwort (Pellia epiphylla), producing arbuscules and vesicles in the hepatic. The extent to which these associations, which are structurally analogous to mycorrhizas, have similar functions remains to be evaluated. Ascomycetous associations are found in a relatively small number of families of leafy liverworts. The structural features of the fungal colonization of rhizoids and underground axes of

  5. Symbiotic fungal associations in 'lower' land plants.

    PubMed Central

    Read, D J; Ducket, J G; Francis, R; Ligron, R; Russell, A

    2000-01-01

    An analysis of the current state of knowledge of symbiotic fungal associations in 'lower' plants is provided. Three fungal phyla, the Zygomycota, Ascomycota and Basidiomycota, are involved in forming these associations, each producing a distinctive suite of structural features in well-defined groups of 'lower' plants. Among the 'lower' plants only mosses and Equisetum appear to lack one or other of these types of association. The salient features of the symbioses produced by each fungal group are described and the relationships between these associations and those formed by the same or related fungi in 'higher' plants are discussed. Particular consideration is given to the question of the extent to which root fungus associations in 'lower' plants are analogous to 'mycorrhizas' of 'higher' plants and the need for analysis of the functional attributes of these symbioses is stressed. Zygomycetous fungi colonize a wide range of extant lower land plants (hornworts, many hepatics, lycopods, Ophioglossales, Psilotales and Gleicheniaceae), where they often produce structures analogous to those seen in the vesicular-arbuscular (VA) mycorrhizas of higher plants, which are formed by members of the order Glomales. A preponderance of associations of this kind is in accordance with palaeohbotanical and molecular evidence indicating that glomalean fungi produced the archetypal symbioses with the first plants to emerge on to land. It is shown, probably for the first time, that glomalean fungi forming typical VA mycorrhiza with a higher plant (Plantago lanceolata) can colonize a thalloid liverwort (Pellia epiphylla), producing arbuscules and vesicles in the hepatic. The extent to which these associations, which are structurally analogous to mycorrhizas, have similar functions remains to be evaluated. Ascomycetous associations are found in a relatively small number of families of leafy liverworts. The structural features of the fungal colonization of rhizoids and underground axes of

  6. Healthcare systems engineering: an interdisciplinary approach to achieving continuous improvement.

    PubMed

    Wu, Bin; Klein, Cerry; Stone, Tamara T

    2006-01-01

    This paper argues that a systems approach can significantly enhance healthcare improvement efforts in patient safety, service quality and healthcare cost containment. The application of systems thinking to healthcare improvement encompasses three key principles: the systems perspective of healthcare processes, structured problem solving and the closed loop of continuous system improvement. These are encapsulated in a conceptual framework of continuous system improvement, which includes a reference architecture model and an analysis and design process model. Combined into a closed-loop, this framework allows users to understand and appropriately apply relevant functions, issues and analytical techniques. Practical applications of the framework are presented. PMID:18048245

  7. Effect of Subliminal Stimulation of Symbiotic Fantasies on Behavior Modification Treatment of Obesity.

    ERIC Educational Resources Information Center

    And Others; Silverman, Lloyd H.

    1978-01-01

    Obese women were treated in behavior modification programs for overeating. Behavior programs were accompanied by subliminal stimulation and by symbiotic and control messages. The symbiotic condition gave evidence of enhancing weight loss. This finding supports the proposition that subliminal stimulation of symbiotic fantasies can enhance the…

  8. Improving Student Achievement Using Expert Learning Systems

    ERIC Educational Resources Information Center

    Green, Ronny; Smith, Bob; Leech, Don

    2004-01-01

    Both educators and the public are demanding improvements in student achievement and school performance. However, students meeting the highest college admission standards are increasingly selecting fields of study other than teaching. How can we increase teacher competence when many of our brightest teacher prospects are going into other fields?…

  9. The Effect of Symbiotic Supplementation on Liver Enzymes, C-reactive Protein and Ultrasound Findings in Patients with Non-alcoholic Fatty Liver Disease: A Clinical Trial

    PubMed Central

    Asgharian, Atefe; Askari, Gholamreza; Esmailzade, Ahmad; Feizi, Awat; Mohammadi, Vida

    2016-01-01

    Background: Regarding to the growing prevalence of nonalcoholic fatty liver disease (NAFLD), concentrating on various strategies to its prevention and management seems necessary. The aim of this study was to determine the effects of symbiotic on C-reactive protein (CRP), liver enzymes, and ultrasound findings in patients with NAFLD. Methods: Eighty NAFLD patients were enrolled in this randomized, double-blind, placebo-controlled clinical trial. Participants received symbiotic in form of a 500 mg capsule (containing seven species of probiotic bacteria and fructooligosaccharides) or a placebo capsule daily for 8 weeks. Ultrasound grading, CRP, and liver enzymes were evaluated at the baseline and the end of the study. Results: In the symbiotic group, ultrasound grade decreased significantly compared to baseline (P < 0.005) but symbiotic supplementation was not associated with changes in alanine aminotransferase (ALT) and aspartate transaminase (AST) levels. In the placebo group, there was no significant change in steatosis grade whereas ALT and AST levels were significantly increased (P = 0.002, P = 0.02, respectively). CRP values remained static in either group. Conclusions: Symbiotic supplementation improved steatosis in NAFLD patients and might be useful in the management of NAFLD or protective against its progression. PMID:27076897

  10. Improving the explanation capabilities of advisory systems

    NASA Technical Reports Server (NTRS)

    Porter, Bruce; Souther, Art

    1994-01-01

    A major limitation of current advisory systems (e.g., intelligent tutoring systems and expert systems) is their restricted ability to give explanations. The goal of our research is to develop and evaluate a flexible explanation facility, one that can dynamically generate responses to questions not anticipated by the system's designers and that can tailor these responses to individual users. To achieve this flexibility, we are developing a large knowledge base, a viewpoint construction facility, and a modeling facility. In the long term we plan to build and evaluate advisory systems with flexible explanation facilities for scientists in numerous domains. In the short term, we are focusing on a single complex domain in biological science, and we are working toward two important milestones: (1) building and evaluating an advisory system with a flexible explanation facility for freshman-level students studying biology, and (2) developing general methods and tools for building similar explanation facilities in other domains.

  11. Improving the explanation capabilities of advisory systems

    NASA Technical Reports Server (NTRS)

    Porter, Bruce; Souther, Art

    1993-01-01

    A major limitation of current advisory systems (e.g., intelligent tutoring systems and expert systems) is their restricted ability to give explanations. The goal of our research is to develop and evaluate a flexible explanation facility, one that can dynamically generate responses to questions not anticipated by the system's designers and that can tailor these responses to individual users. To achieve this flexibility, we are developing a large knowledge base, a viewpoint construction facility, and a modeling facility. In the long term we plan to build and evaluate advisory systems with flexible explanation facilities for scientists in numerous domains. In the short term, we are focusing on a single complex domain in biological science, and we are working toward two important milestones: (1) building and evaluating an advisory system with a flexible explanation facility for freshman-level students studying biology; and (2) developing general methods and tools for building similar explanation facilities in other domains.

  12. IPHAS and the symbiotic stars . II. New discoveries and a sample of the most common mimics

    NASA Astrophysics Data System (ADS)

    Corradi, R. L. M.; Valentini, M.; Munari, U.; Drew, J. E.; Rodríguez-Flores, E. R.; Viironen, K.; Greimel, R.; Santander-García, M.; Sabin, L.; Mampaso, A.; Parker, Q.; DePew, K.; Sale, S. E.; Unruh, Y. C.; Vink, J. S.; Rodríguez-Gil, P.; Barlow, M. J.; Lennon, D. J.; Groot, P. J.; Giammanco, C.; Zijlstra, A. A.; Walton, N. A.

    2010-01-01

    Context. Knowledge of the total population of symbiotic stars in the Galaxy is important for understanding basic aspects of stellar evolution in interacting binaries and the relevance of this class of objects in the formation of supernovae of type Ia. Aims: In a previous paper, we presented the selection criteria needed to search for symbiotic stars in IPHAS, the INT Hα survey of the Northern Galactic plane. IPHAS gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume. Methods: Follow-up spectroscopy at different telescopes worldwide of a sample of sixty two symbiotic star candidates is presented. Results: Seven out of nineteen S-type candidates observed spectroscopically are confirmed to be genuine symbiotic stars. The spectral type of their red giant components, as well as reddening and distance, were computed by modelling the spectra. Only one new D-type symbiotic system, out of forty-three candidates observed, was found. This was as expected (see discussion in our paper on the selection criteria). The object shows evidence for a high density outflow expanding at a speed ≥65 km s-1. Most of the other candidates are lightly reddened classical T Tauri stars and more highly reddened young stellar objects that may be either more massive young stars of HAeBe type or classical Be stars. In addition, a few notable objects have been found, such as three new Wolf-Rayet stars and two relatively high-luminosity evolved massive stars. We also found a helium-rich source, possibly a dense ejecta hiding a WR star, which is surrounded by a large ionized nebula. Conclusions: These spectroscopic data allow us to refine the selection criteria for symbiotic stars in the IPHAS survey and, more generally, to better understand the behaviour of different Hα emitters in the IPHAS and 2MASS colour-colour diagrams. Based on observations obtained at; the 2.6 m Nordic Optical Telescope operated by NOTSA; the 2.5 m INT and 4.2 m

  13. Film processing investigation. [improved chemical mixing system

    NASA Technical Reports Server (NTRS)

    Kelly, J. L.

    1972-01-01

    The present operational chemical mixing system for the Photographic Technology Division is evaluated, and the limitations are defined in terms of meeting the present and programmed chemical supply and delivery requirements. A major redesign of the entire chemical mixing, storage, analysis, and supply system is recommended. Other requirements for immediate and future implementations are presented.

  14. Feedback Improvement in Automatic Program Evaluation Systems

    ERIC Educational Resources Information Center

    Skupas, Bronius

    2010-01-01

    Automatic program evaluation is a way to assess source program files. These techniques are used in learning management environments, programming exams and contest systems. However, use of automated program evaluation encounters problems: some evaluations are not clear for the students and the system messages do not show reasons for lost points.…

  15. Changing and Improving Educational Systems and Institutions.

    ERIC Educational Resources Information Center

    Thomas, A. Ross

    Research into the process of educational change has centered largely around the diffusion concept--the spread or permeation of an innovation from system to system or from school to school throughout a particular state or number of states. It is as if many teachers and administrators have understood the purpose of educational change to be the…

  16. Reliability improvement of distribution systems using SSVR.

    PubMed

    Hosseini, Mehdi; Shayanfar, Heidar Ali; Fotuhi-Firuzabad, Mahmoud

    2009-01-01

    This paper presents a reliability assessment algorithm for distribution systems using a Static Series Voltage Regulator (SSVR). Furthermore, this algorithm considers the effects of Distributed Generation (DG) units, alternative sources, system reconfiguration, load shedding and load adding on distribution system reliability indices. In this algorithm, load points are classified into 8 types and separated restoration times are considered for each class. Comparative studies are conducted to investigate the impacts of DG and alternative source unavailability on the distribution system reliability. For reliability assessment, the customer-oriented reliability indices such as SAIFI, SAIDI, CAIDI ASUI and also load- and energy-oriented indices such as ENS and AENS are evaluated. The effectiveness of the proposed algorithm is examined on the two standard distribution systems consisting of 33 and 69 nodes. The best location of the SSVR in distribution systems is determined based on different reliability indices, separately. Results show that the proposed algorithm is efficient for large-scale radial distribution systems and can accommodate the effects of fault isolation and load restoration. PMID:19006802

  17. Improved Large-Field Focusing Schlieren System

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.

    1993-01-01

    System used to examine complicated two- and three-dimensional flows. High-brightness large-field focusing schlieren system incorporates Fresnel lens instead of glass diffuser. In system with large field of view, image may also be very large. Relay optical subsystem minifies large image while retaining all of light. Facilities candidates for use of focusing schlieren include low-speed wind and water tunnels. Heated or cooled flow tracers or injected low- or high-density tracers used to make flows visible for photographic recording.

  18. Improving pumping system efficiency at coal plants

    SciTech Connect

    Livoti, W.C.; McCandless, S.; Poltorak, R.

    2009-03-15

    The industry must employ ultramodern technologies when building or upgrading power plant pumping systems thereby using fuels more efficiently. The article discusses the uses and efficiencies of positive displacement pumps, centrifugal pumps and multiple screw pumps. 1 ref., 4 figs.

  19. Designing Bioretention Systems to Improve Nitrogen Removal

    EPA Science Inventory

    Bioretention systems effectively remove many stormwater stressors, including oil/grease, heavy metals, phosphorus, and ammonium. However, reported nitrate removal performance is highly variable. Bioretention media is typically coarse-grained with low organic matter content, which...

  20. How regional trauma systems improve outcomes.

    PubMed

    Cole, Elaine

    2015-10-01

    Management of severely injured patients is complex and requires organised, expert care. Regionalised trauma systems are relatively new in the UK and aim to deliver optimal, timely care to injured patients at the most appropriate location. This article discusses the drivers, organisation, processes and outcomes of regionalised trauma care. It also describes the challenges and benefits of working within a trauma system to enable emergency practitioners to reflect on their roles in contemporary trauma care. PMID:26451941

  1. Multiresponse imaging system design for improved resolution

    NASA Technical Reports Server (NTRS)

    Alter-Gartenberg, Rachel; Fales, Carl L.; Huck, Friedrich O.; Rahman, Zia-Ur; Reichenbach, Stephen E.

    1991-01-01

    Multiresponse imaging is a process that acquires A images, each with a different optical response, and reassembles them into a single image with an improved resolution that can approach 1/sq rt A times the photodetector-array sampling lattice. Our goals are to optimize the performance of this process in terms of the resolution and fidelity of the restored image and to assess the amount of information required to do so. The theoretical approach is based on the extension of both image restoration and rate-distortion theories from their traditional realm of signal processing to image processing which includes image gathering and display.

  2. Improved Dichroics For Microwave Reflector Antenna Systems

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao

    1995-01-01

    Panel contains array of grid and square conductive loops as array elements designed to reflect most of incident electromagnetic radiation in K(subu) band (13.5 to 15.5 GHz) and to pass that in X band (7 to 9 GHz). Designed to exhibit this dichroic property at angles of incidence up to 40 degrees in transverse electric, transverse magnetic, or circular polarization. Concept of gridded-square-loop dichroic array related to double-loop dichroic arrays described in "Frequency-Selective Microwave Reflectors" (NPO-18701). Improved version exhibits smaller shift of resonant frequency with angle of incidence.

  3. Systems and methods for improved telepresence

    DOEpatents

    Anderson, Matthew O.; Willis, W. David; Kinoshita, Robert A.

    2005-10-25

    The present invention provides a modular, flexible system for deploying multiple video perception technologies. The telepresence system of the present invention is capable of allowing an operator to control multiple mono and stereo video inputs in a hands-free manner. The raw data generated by the input devices is processed into a common zone structure that corresponds to the commands of the user, and the commands represented by the zone structure are transmitted to the appropriate device. This modularized approach permits input devices to be easily interfaced with various telepresence devices. Additionally, new input devices and telepresence devices are easily added to the system and are frequently interchangeable. The present invention also provides a modular configuration component that allows an operator to define a plurality of views each of which defines the telepresence devices to be controlled by a particular input device. The present invention provides a modular flexible system for providing telepresence for a wide range of applications. The modularization of the software components combined with the generalized zone concept allows the systems and methods of the present invention to be easily expanded to encompass new devices and new uses.

  4. Nodulation outer proteins: double-edged swords of symbiotic rhizobia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation is the result of a complex bacterial infection process, which depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial nodulation outer proteins (Nops)...

  5. The prototype symbiotic star AX Per is in outburst

    NASA Astrophysics Data System (ADS)

    Munari, U.; Dallaporta, S.; Righetti, G. L.; Castellani, F.; Cherini, G.

    2014-08-01

    The prototype symbiotic star AX Per is in outburst. This is the third such event in the current series of outbursts, the previous two peaking at V=10.41 on 2009 May 26 and at V=10.03 on 2012 Aug 28, according to ANS Collaboration intensive monitoring.

  6. Improved OTEC System for a Submarine Robot

    NASA Technical Reports Server (NTRS)

    Chao, Yi; Jones, Jack; Valdez, Thomas

    2010-01-01

    An ocean thermal energy conversion (OTEC), now undergoing development, is a less-massive, more-efficient means of exploiting the same basic principle as that of the proposed system described in "Alternative OTEC Scheme for a Submarine Robot" (NPO-43500), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 50. The proposed system as described previously would be based on the thawing-expansion/freezing-contraction behavior of a wax or perhaps another suitable phase-change material (PCM). The power generated by the system would be used to recharge the batteries in a battery- powered unmanned underwater vehicle [UUV (essentially, a small exploratory submarine robot)] of a type that has been deployed in large numbers in research pertaining to global warming. A UUV of this type travels between the ocean surface and depths, measuring temperature and salinity. At one phase of its operational cycle, the previously proposed system would utilize the surface ocean temperature (which lies between 15 and 30 C over most of the Earth) to melt a PCM that has a melting/freezing temperature of about 10 C. At the opposite phase of its operational cycle, the system would utilize the lower ocean temperature at depth (e.g., between 4 and 7 C at a depth of 300 m) to freeze the PCM. The melting or freezing would cause the PCM to expand or contract, respectively, by about 9 volume percent. The PCM would be contained in tubes that would be capable of expanding and contracting with the PCM. The PCM-containing tubes would be immersed in a hydraulic fluid. The expansion and contraction would drive a flow of the hydraulic fluid against a piston that, in turn, would push a rack-and-pinion gear system to spin a generator to charge a battery.

  7. Improving Fan System Performance: A Sourcebook for Industry

    SciTech Connect

    2003-04-01

    This is one of a series of sourcebooks on motor-driven equipment produced by the Industrial Technologies Program. It provides a reference for industrial fan systems users, outlining opportunities to improve fan system performance.

  8. Improving Compressed Air System Performance: A Sourcebook for Industry

    SciTech Connect

    2003-11-01

    NREL will produce this sourcebook for DOE's Industrial Technologies Office as part of a series of documents on industrial energy equipment. The sourcebook is a reference for industrial compressed air system users, outlining opportunities to improve system efficiency.

  9. Improved thermal isolation for superconducting magnet systems

    NASA Technical Reports Server (NTRS)

    Wiebe, E. R.

    1974-01-01

    Closed-cycle refrigerating system for superconductive magnet and maser is operated in vacuum environment. Each wire leading from external power source passes through cooling station which blocks heat conduction. In connection with these stations, switch with small incandescent light bulb, which generates heat, is used to stop superconduction.

  10. Philadelphia's Teacher Appraisal System Needs Improvement

    ERIC Educational Resources Information Center

    Royal, Camika; Tossman, Matthew

    2009-01-01

    The purpose of this paper is to inform the community about teacher appraisal methods in the School District of Philadelphia, outline the difficulties of the current system, and suggest approaches that would strengthen the teacher appraisal process. The authors gathered their information over three months in mid-2009 from multiple sources:…