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Sample records for co2brayton cycle control

  1. Scaling considerations for a multi-megawatt class supercritical CO2 brayton cycle and commercialization.

    SciTech Connect

    Fleming, Darryn D.; Holschuh, Thomas Vernon,; Conboy, Thomas M.; Pasch, James Jay; Wright, Steven A; Rochau, Gary E; Fuller, Robert Lynn

    2013-11-01

    Small-scale supercritical CO2 demonstration loops are successful at identifying the important technical issues that one must face in order to scale up to larger power levels. The Sandia National Laboratories supercritical CO2 Brayton cycle test loops are identifying technical needs to scale the technology to commercial power levels such as 10 MWe. The small size of the Sandia 1 MWth loop has demonstration of the split flow loop efficiency and effectiveness of the Printed Circuit Heat Exchangers (PCHXs) leading to the design of a fully recuperated, split flow, supercritical CO2 Brayton cycle demonstration system. However, there were many problems that were encountered, such as high rotational speeds in the units. Additionally, the turbomachinery in the test loops need to identify issues concerning the bearings, seals, thermal boundaries, and motor controller problems in order to be proved a reliable power source in the 300 kWe range. Although these issues were anticipated in smaller demonstration units, commercially scaled hardware would eliminate these problems caused by high rotational speeds at small scale. The economic viability and development of the future scalable 10 MWe solely depends on the interest of DOE and private industry. The Intellectual Property collected by Sandia proves that the ~10 MWe supercritical CO2 power conversion loop to be very beneficial when coupled to a 20 MWth heat source (either solar, geothermal, fossil, or nuclear). This paper will identify a commercialization plan, as well as, a roadmap from the simple 1 MWth supercritical CO2 development loop to a power producing 10 MWe supercritical CO2 Brayton loop.

  2. Operation and analysis of a supercritical CO2 Brayton cycle.

    SciTech Connect

    Wright, Steven Alan; Radel, Ross F.; Vernon, Milton E.; Pickard, Paul S.; Rochau, Gary Eugene

    2010-09-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for use with solar, nuclear or fossil heat sources. The focus of this work has been on the supercritical CO{sub 2} cycle (S-CO2) which has the potential for high efficiency in the temperature range of interest for these heat sources, and is also very compact, with the potential for lower capital costs. The first step in the development of these advanced cycles was the construction of a small scale Brayton cycle loop, funded by the Laboratory Directed Research & Development program, to study the key issue of compression near the critical point of CO{sub 2}. This document outlines the design of the small scale loop, describes the major components, presents models of system performance, including losses, leakage, windage, compressor performance, and flow map predictions, and finally describes the experimental results that have been generated.

  3. Automatic control of clock duty cycle

    NASA Technical Reports Server (NTRS)

    Feng, Xiaoxin (Inventor); Roper, Weston (Inventor); Seefeldt, James D. (Inventor)

    2010-01-01

    In general, this disclosure is directed to a duty cycle correction (DCC) circuit that adjusts a falling edge of a clock signal to achieve a desired duty cycle. In some examples, the DCC circuit may generate a pulse in response to a falling edge of an input clock signal, delay the pulse based on a control voltage, adjust the falling edge of the input clock signal based on the delayed pulse to produce an output clock signal, and adjust the control voltage based on the difference between a duty cycle of the output clock signal and a desired duty cycle. Since the DCC circuit adjusts the falling edge of the clock cycle to achieve a desired duty cycle, the DCC may be incorporated into existing PLL control loops that adjust the rising edge of a clock signal without interfering with the operation of such PLL control loops.

  4. Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Structural and creep-fatigue evaluation

    DOE PAGESBeta

    Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; Ho, Clifford; Dutta, Pradip

    2016-06-06

    A supercritical carbon dioxide (sCO2) Brayton cycle is an emerging high energy-density cycle undergoing extensive research due to the appealing thermo-physical properties of sCO2 and single phase operation. Development of a solar receiver capable of delivering sCO2 at 20 MPa and 700 °C is required for implementation of the high efficiency (~50%) solar powered sCO2 Brayton cycle. In this work, extensive candidate materials are review along with tube size optimization using the ASME Boiler and Pressure Vessel Code. Moreover, temperature and pressure distribution obtained from the thermal-fluid modeling (presented in a complementary publication) are used to evaluate the thermal andmore » mechanical stresses along with detailed creep-fatigue analysis of the tubes. For resulting body stresses were used to approximate the lifetime performance of the receiver tubes. A cyclic loading analysis is performed by coupling the Strain-Life approach and the Larson-Miller creep model. The structural integrity of the receiver was examined and it was found that the stresses can be withstood by specific tubes, determined by a parametric geometric analysis. The creep-fatigue analysis display the damage accumulation due to cycling and the permanent deformation on the tubes showed that the tubes can operate for the full lifetime of the receiver.« less

  5. Variable pressure power cycle and control system

    DOEpatents

    Goldsberry, Fred L.

    1984-11-27

    A variable pressure power cycle and control system that is adjustable to a variable heat source is disclosed. The power cycle adjusts itself to the heat source so that a minimal temperature difference is maintained between the heat source fluid and the power cycle working fluid, thereby substantially matching the thermodynamic envelope of the power cycle to the thermodynamic envelope of the heat source. Adjustments are made by sensing the inlet temperature of the heat source fluid and then setting a superheated vapor temperature and pressure to achieve a minimum temperature difference between the heat source fluid and the working fluid.

  6. A festival of cell-cycle controls.

    PubMed

    Haase, S B; Clarke, D J

    2001-11-01

    The second biennial Salk Cell Cycle meeting convened on 22 June 2001 in San Diego, California. Organized by Tony Hunter and Susan Forsburg of the Salk Institute, the five-day conference was highlighted by enlightening science and plenty of San Diego sunshine. Presentations covered a broad range of contemporary cell-cycle topics, ranging from regulation of DNA replication and mitosis to DNA damage recognition and checkpoint control.

  7. Metabolic control of the cell cycle

    PubMed Central

    Kalucka, Joanna; Missiaen, Rindert; Georgiadou, Maria; Schoors, Sandra; Lange, Christian; De Bock, Katrien; Dewerchin, Mieke; Carmeliet, Peter

    2015-01-01

    Cell division is a metabolically demanding process, requiring the production of large amounts of energy and biomass. Not surprisingly therefore, a cell's decision to initiate division is co-determined by its metabolic status and the availability of nutrients. Emerging evidence reveals that metabolism is not only undergoing substantial changes during the cell cycle, but it is becoming equally clear that metabolism regulates cell cycle progression. Here, we overview the emerging role of those metabolic pathways that have been best characterized to change during or influence cell cycle progression. We then studied how Notch signaling, a key angiogenic pathway that inhibits endothelial cell (EC) proliferation, controls EC metabolism (glycolysis) during the cell cycle. PMID:26431254

  8. Neuromuscular Control and Coordination during Cycling

    ERIC Educational Resources Information Center

    Li, Li

    2004-01-01

    The neuromuscular control aspect of cycling has been investigated through the effects of modifying posture and cadence. These studies show that changing posture has a more profound influence on neuromuscular coordination than does changing slope. Most of the changes with standing posture occur late in the downstroke: increased ankle and knee joint…

  9. Control points within the cell cycle

    SciTech Connect

    Van't Hof, J.

    1984-01-01

    Evidence of the temporal order of chromosomal DNA replication argues favorably for the view that the cell cycle is controlled by genes acting in sequence whose time of expression is determined by mitosis and the amount of nuclear DNA (2C vs 4C) in the cell. Gl and G2 appear to be carbohydrate dependent in that cells starved of either carbohydrate of phosphate fail to make these transitions. Cells deprived of nitrate, however, fail only at Gl to S transition indicating that the controls that operate in G1 differ from those that operate in G2. 46 references, 5 figures.

  10. Supercritical carbon dioxide cycle control analysis.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.

    2011-04-11

    This report documents work carried out during FY 2008 on further investigation of control strategies for supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle energy converters. The main focus of the present work has been on investigation of the S-CO{sub 2} cycle control and behavior under conditions not covered by previous work. An important scenario which has not been previously calculated involves cycle operation for a Sodium-Cooled Fast Reactor (SFR) following a reactor scram event and the transition to the primary coolant natural circulation and decay heat removal. The Argonne National Laboratory (ANL) Plant Dynamics Code has been applied to investigate the dynamic behavior of the 96 MWe (250 MWt) Advanced Burner Test Reactor (ABTR) S-CO{sub 2} Brayton cycle following scram. The timescale for the primary sodium flowrate to coast down and the transition to natural circulation to occur was calculated with the SAS4A/SASSYS-1 computer code and found to be about 400 seconds. It is assumed that after this time, decay heat is removed by the normal ABTR shutdown heat removal system incorporating a dedicated shutdown heat removal S-CO{sub 2} pump and cooler. The ANL Plant Dynamics Code configured for the Small Secure Transportable Autonomous Reactor (SSTAR) Lead-Cooled Fast Reactor (LFR) was utilized to model the S-CO{sub 2} Brayton cycle with a decaying liquid metal coolant flow to the Pb-to-CO{sub 2} heat exchangers and temperatures reflecting the decaying core power and heat removal by the cycle. The results obtained in this manner are approximate but indicative of the cycle transient performance. The ANL Plant Dynamics Code calculations show that the S-CO{sub 2} cycle can operate for about 400 seconds following the reactor scram driven by the thermal energy stored in the reactor structures and coolant such that heat removal from the reactor exceeds the decay heat generation. Based on the results, requirements for the shutdown heat removal system may be defined

  11. Size sensors in bacteria, cell cycle control, and size control

    PubMed Central

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation. PMID:26074903

  12. Size sensors in bacteria, cell cycle control, and size control.

    PubMed

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation.

  13. Supercritical CO2 Power Cycles: Design Considerations for Concentrating Solar Power

    SciTech Connect

    Neises, Ty; Turchi, Craig

    2014-09-01

    A comparison of three supercritical CO2 Brayton cycles: the simple cycle, recompression cycle and partial-cooling cycle indicates the partial-cooling cycle is favored for use in concentrating solar power (CSP) systems. Although it displays slightly lower cycle efficiency versus the recompression cycle, the partial-cooling cycle is estimated to have lower total recuperator size, as well as a lower maximum s-CO2 temperature in the high-temperature recuperator. Both of these effects reduce recuperator cost. Furthermore, the partial-cooling cycle provides a larger temperature differential across the turbine, which translates into a smaller, more cost-effective thermal energy storage system. The temperature drop across the turbine (and by extension, across a thermal storage system) for the partial-cooling cycle is estimated to be 23% to 35% larger compared to the recompression cycle of equal recuperator conductance between 5 and 15 MW/K. This reduces the size and cost of the thermal storage system. Simulations by NREL and Abengoa Solar indicate the partial-cooling cycle results in a lower LCOE compared with the recompression cycle, despite the former's slightly lower cycle efficiency. Advantages of the recompression cycle include higher thermal efficiency and potential for a smaller precooler. The overall impact favors the use of a partial-cooling cycle for CSP compared to the more commonly analyzed recompression cycle.

  14. Optimization and Comparison of Direct and Indirect Supercritical Carbon Dioxide Power Plant Cycles for Nuclear Applications

    SciTech Connect

    Edwin A. Harvego; Michael G. McKellar

    2011-11-01

    There have been a number of studies involving the use of gases operating in the supercritical mode for power production and process heat applications. Supercritical carbon dioxide (CO2) is particularly attractive because it is capable of achieving relatively high power conversion cycle efficiencies in the temperature range between 550 C and 750 C. Therefore, it has the potential for use with any type of high-temperature nuclear reactor concept, assuming reactor core outlet temperatures of at least 550 C. The particular power cycle investigated in this paper is a supercritical CO2 Recompression Brayton Cycle. The CO2 Recompression Brayton Cycle can be used as either a direct or indirect power conversion cycle, depending on the reactor type and reactor outlet temperature. The advantage of this cycle when compared to the helium Brayton cycle is the lower required operating temperature; 550 C versus 850 C. However, the supercritical CO2 Recompression Brayton Cycle requires an operating pressure in the range of 20 MPa, which is considerably higher than the required helium Brayton cycle operating pressure of 8 MPa. This paper presents results of analyses performed using the UniSim process analyses software to evaluate the performance of both a direct and indirect supercritical CO2 Brayton Recompression cycle for different reactor outlet temperatures. The direct supercritical CO2 cycle transferred heat directly from a 600 MWt reactor to the supercritical CO2 working fluid supplied to the turbine generator at approximately 20 MPa. The indirect supercritical CO2 cycle assumed a helium-cooled Very High Temperature Reactor (VHTR), operating at a primary system pressure of approximately 7.0 MPa, delivered heat through an intermediate heat exchanger to the secondary indirect supercritical CO2 Brayton Recompression cycle, again operating at a pressure of about 20 MPa. For both the direct and indirect cycles, sensitivity calculations were performed for reactor outlet temperature

  15. Feedback and Modularity in Cell Cycle Control

    NASA Astrophysics Data System (ADS)

    Skotheim, Jan

    2009-03-01

    Underlying the wonderful diversity of natural forms is the ability of an organism to grow into its appropriate shape. Regulation ensures that cells grow, divide and differentiate so that the organism and its constitutive parts are properly proportioned and of suitable size. Although the size-control mechanism active in an individual cell is of fundamental importance to this process, it is difficult to isolate and study in complex multi-cellular systems and remains poorly understood. This motivates our use of the budding yeast model organism, whose Start checkpoint integrates multiple internal (e.g. cell size) and external signals into an irreversible decision to enter the cell cycle. We have endeavored to address the following two questions: What makes the Start transition irreversible? How does a cell compute its own size? I will report on the progress we have made. Our work is part of an emerging framework for understanding biological control circuits, which will allow us to discern the function of natural systems and aid us in engineering synthetic systems.

  16. Random transitions and cell cycle control.

    PubMed

    Brooks, R F

    1981-01-01

    Differences between the cycle times of sister cells are exponentially distributed, which means that these differences can be explained entirely by the existence of a single critical step in the cell cycle which occurs at random. Cycle times as a whole are not exponentially distributed, indicating an additional source of variation in the cell cycle. It follows that this additional variation must affect sister cells identically; ie, sister cell cycle times are correlated. This correlation and the overall distribution of cycle times can be predicted quantitatively by a model that was developed initially in order to explain certain problematic features of the response of quiescent cells to mitogenic stimulation - in particular, the significance of the lag that almost invariably occurs between stimulation and the onset of DNA synthesis. This model proposes that each cell cycle depends not on one but two random transitions, one of which (at reasonably high growth rates) occurs in the mother cell, its effects being inherited equally by the two daughter cells. The fundamental timing element in the cell cycle is proposed to be a lengthy process, called L, which accounts for most of the lag on mitogenic stimulation and also for the minimum cycle time in growing cultures. One of the random transitions is concerned with the initiation of L, whereas the other becomes possible on completion of L. The latter transition has two consequences: the first is the initiation of a sequence of events which includes S, G2 and M; the second is the restoration of the state from which L may be initiated once more. As a result, L may begin (at random) at any stage of the conventional cycle, ie, S, G2, M, or G1. There are marked similarities between the hypothetical process L and the biogenesis of mitotic centres - the structures responsible for organising the spindle poles. PMID:7312875

  17. Controls over nitrogen cycling in California chaparral

    NASA Astrophysics Data System (ADS)

    Hanan, E. J.; Schimel, J.

    2013-12-01

    Chaparral landscapes of southern California and other Mediterranean-type ecosystems are structured by fire. They exist in environments that typically do not receive rain for 6 months or more at a time, making combustion inevitable. The heavy winter rains following fire can erode soil and leach nutrients such as nitrogen into streams and reservoirs, particularly along slopes that have been denuded. The extent to which nitrogen is cycled and redistributed following fire is a function of the rate at which soil microbes metabolize nitrogen into mobile forms such as nitrate. However, the specific mechanisms controlling nitrogen metabolism in chaparral are not fully understood. We measured mineralization and nitrification rates in ecosystems dominated by species typical of southern and central California chaparral, and conducted a laboratory incubation to experimentally examine the influence of pH, charcoal, and ammonium supply on nitrogen dynamics. Nitrate production was significantly enhanced in recently burned chaparral, which correlated with elevated soil pH. Enhanced pH can both raise the solubility of soil organic matter, and stimulate nitrification, while fires simultaneously release nitrifying bacteria from competition with vegetation for ammonium. To further explore these processes, we applied ammonium, pH, and charcoal treatments to samples from 4 chaparral stands, which burned 1, 4, 20 and 40 years ago, using a factorial design. Treated soils were incubated in mason jars at 50% water holding capacity for 8 weeks. Soil respiration, substrate induced respiration, mineralization, nitrification, and nitrification potential were measured periodically to evaluate whether ammonium addition, pH and the presence of charcoal influence substrate production and nitrification. The threat nitrate of leaching following fire grows with climate change, because fire and precipitation regimes are expected to become both increasingly variable and punctuated by more intense events

  18. Prediction and control of limit cycling motions in boosting rockets

    NASA Astrophysics Data System (ADS)

    Newman, Brett

    An investigation concerning the prediction and control of observed limit cycling behavior in a boosting rocket is considered. The suspected source of the nonlinear behavior is the presence of Coulomb friction in the nozzle pivot mechanism. A classical sinusoidal describing function analysis is used to accurately recreate and predict the observed oscillatory characteristic. In so doing, insight is offered into the limit cycling mechanism and confidence is gained in the closed-loop system design. Nonlinear simulation results are further used to support and verify the results obtained from describing function theory. Insight into the limit cycling behavior is, in turn, used to adjust control system parameters in order to passively control the oscillatory tendencies. Tradeoffs with the guidance and control system stability/performance are also noted. Finally, active control of the limit cycling behavior, using a novel feedback algorithm to adjust the inherent nozzle sticking-unsticking characteristics, is considered.

  19. Controls on the CO2 seasonal cycle

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.; Forget, F.; Haberle, Robert M.; Schaeffer, J.; Lee, H.

    1993-01-01

    Surface pressure measurement performed by the Viking landers show substantial variations in pressure on seasonal timescales that are characterized by two local minima and two local maxima. These variations have widely been attributed to the seasonal condensation and sublimation of CO2 in the two polar regions. It has been somewhat of a surprise that the amplitude of the minimum and maximum that is dominated by the CO2 cycle in the north was much weaker than the corresponding amplitude of the south-dominated extrema. Another surprise was that the seasonal pressure cycle during years 2 and 3 of the Viking mission was so similar to that for year 1, despite the occurrence of two global dust storms during year 1 and none during years 2 and 3. An energy balance model that incorporates dynamical factors from general circulation model (GCM) runs in which the atmospheric dust opacity and seasonal date were systematically varied was used to model the observed seasonal pressure variations. The energy balance takes account of the following processes in determining the rates of CO2 condensation and sublimation at each longitudinal and latitudinal grid point: solar radiation, infrared radiation from the atmosphere and surface, subsurface heat conduction, and atmospheric heat advection. Condensation rates are calculated both at the surface and in the atmosphere. In addition, the energy balance model also incorporates information from the GCM runs on seasonal redistribution of surface pressure across the globe. Estimates of surface temperature of the seasonal CO2 caps were used to define the infrared radiative losses from the seasonal polar caps. The seasonal pressure variations measured at the Viking lander sites were closely reproduced.

  20. Dilution cycle control for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    A dilution cycle control system for an absorption refrigeration system is disclosed. The control system includes a time delay relay for sensing shutdown of the absorption refrigeration system and for generating a control signal only after expiration of a preselected time period measured from the sensed shutdown of the absorption refrigeration system, during which the absorption refrigeration system is not restarted. A dilution cycle for the absorption refrigeration system is initiated in response to generation of a control signal by the time delay relay. This control system is particularly suitable for use with an absorption refrigeration system which is frequently cycled on and off since the time delay provided by the control system prevents needless dilution of the absorption refrigeration system when the system is turned off for only a short period of time and then is turned back on.

  1. Redox Control of the Cell Cycle in Health and Disease

    PubMed Central

    Sarsour, Ehab H.; Kumar, Maneesh G.; Chaudhuri, Leena; Kalen, Amanda L.

    2009-01-01

    Abstract The cellular oxidation and reduction (redox) environment is influenced by the production and removal of reactive oxygen species (ROS). In recent years, several reports support the hypothesis that cellular ROS levels could function as “second messengers” regulating numerous cellular processes, including proliferation. Periodic oscillations in the cellular redox environment, a redox cycle, regulate cell-cycle progression from quiescence (G0) to proliferation (G1, S, G2, and M) and back to quiescence. A loss in the redox control of the cell cycle could lead to aberrant proliferation, a hallmark of various human pathologies. This review discusses the literature that supports the concept of a redox cycle controlling the mammalian cell cycle, with an emphasis on how this control relates to proliferative disorders including cancer, wound healing, fibrosis, cardiovascular diseases, diabetes, and neurodegenerative diseases. We hypothesize that reestablishing the redox control of the cell cycle by manipulating the cellular redox environment could improve many aspects of the proliferative disorders. Antioxid. Redox Signal. 11, 2985–3011. PMID:19505186

  2. Landscape controls on carbon and nitrogen cycling in boreal forests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate change in the boreal forest biome is having a large impact on two of the main controllers of carbon (C) and nitrogen (N) cycling within this region: permafrost and fire. Permafrost, and its effects on soil drainage, controls the inputs and losses of C and N via net primary productivity (NP...

  3. Control system options and strategies for supercritical CO2 cycles.

    SciTech Connect

    Moisseytsev, A.; Kulesza, K. P.; Sienicki, J. J.; Nuclear Engineering Division; Oregon State Univ.

    2009-06-18

    The Supercritical Carbon Dioxide (S-CO{sub 2}) Brayton Cycle is a promising alternative to Rankine steam cycle and recuperated gas Brayton cycle energy converters for use with Sodium-Cooled Fast Reactors (SFRs), Lead-Cooled Fast Reactors (LFRs), as well as other advanced reactor concepts. The S-CO{sub 2} Brayton Cycle offers higher plant efficiencies than Rankine or recuperated gas Brayton cycles operating at the same liquid metal reactor core outlet temperatures as well as reduced costs or size of key components especially the turbomachinery. A new Plant Dynamics Computer Code has been developed at Argonne National Laboratory for simulation of a S-CO{sub 2} Brayton Cycle energy converter coupled to an autonomous load following liquid metal-cooled fast reactor. The Plant Dynamics code has been applied to investigate the effectiveness of a control strategy for the S-CO{sub 2} Brayton Cycle for the STAR-LM 181 MWe (400 MWt) Lead-Cooled Fast Reactor. The strategy, which involves a combination of control mechanisms, is found to be effective for controlling the S-CO{sub 2} Brayton Cycle over the complete operating range from 0 to 100 % load for a representative set of transient load changes. While the system dynamic analysis of control strategy performance for STARLM is carried out for a S-CO{sub 2} Brayton Cycle energy converter incorporating an axial flow turbine and compressors, investigations of the S-CO{sub 2} Brayton Cycle have identified benefits from the use of centrifugal compressors which offer a wider operating range, greater stability near the critical point, and potentially further cost reductions due to fewer stages than axial flow compressors. Models have been developed at Argonne for the conceptual design and performance analysis of centrifugal compressors for use in the SCO{sub 2} Brayton Cycle. Steady state calculations demonstrate the wider operating range of centrifugal compressors versus axial compressors installed in a S-CO{sub 2} Brayton Cycle as

  4. Few-cycle plasmon oscillations controlling photoemission from metal nanoparticles

    SciTech Connect

    Földi, Péter; Márton, István; Német, Nikolett; Dombi, Péter; Ayadi, Viktor

    2015-01-05

    Few-cycle optical excitation of nanosystems holds promise of fundamental discoveries and applications in ultrafast nanoscience, the development of nanostructured photocathodes, and many more. For these, surface plasmon generation on unprecedented timescales needs to be controlled. For this, few-cycle plasmon oscillations on a metal nanoparticle can be generated by keeping considerable electric field enhancement factors. As an initial application of such a high spatiotemporal localization of an ultrashort laser pulse, we numerically demonstrate the control of photoelectrons on a true sub-fs timescale in nanometric spatial domains. We show that it is only off-resonant nanoparticles that can provide few-cycle plasmons and electron control on this timescale.

  5. Preliminary Tests of a Practical Fuzzy FES Controller Based on Cycle-to-Cycle Control in the Knee Flexion and Extension Control

    NASA Astrophysics Data System (ADS)

    Watanabe, Takashi; Masuko, Tomoya; Arifin, Achmad

    The fuzzy controller based on cycle-to-cycle control with output value adjustment factors (OAF) was developed for restoring gait of paralyzed subjects by using functional electrical stimulation (FES). Results of maximum knee flexion and extension controls with neurologically intact subjects suggested that the OAFs would be effective in reaching the target within small number of cycles and in reducing the error after reaching the target. Oscillating responses between cycles were also suppressed. The fuzzy controller was expected to be examined to optimize the OAFs with more subjects including paralyzed patients for clinical application.

  6. Cell proliferation and cell cycle control: a mini review.

    PubMed

    Golias, C H; Charalabopoulos, A; Charalabopoulos, K

    2004-12-01

    Tumourigenesis is the result of cell cycle disorganisation, leading to an uncontrolled cellular proliferation. Specific cellular processes-mechanisms that control cell cycle progression and checkpoint traversation through the intermitotic phases are deregulated. Normally, these events are highly conserved due to the existence of conservatory mechanisms and molecules such as cell cycle genes and their products: cyclins, cyclin dependent kinases (Cdks), Cdk inhibitors (CKI) and extra cellular factors (i.e. growth factors). Revolutionary techniques using laser cytometry and commercial software are available to quantify and evaluate cell cycle processes and cellular growth. S-phase fraction measurements, including ploidy values, using histograms and estimation of indices such as the mitotic index and tumour-doubling time indices, provide adequate information to the clinician to evaluate tumour aggressiveness, prognosis and the strategies for radiotherapy and chemotherapy in experimental researches.

  7. Variable cycle stirling engine and gas leakage control system therefor

    SciTech Connect

    Otters, J.

    1984-12-25

    An improved thermal engine of the type having a displacer body movable between the hot end and the cold end of a chamber for subjecting a fluid within that chamber to a thermodynamic cycle and having a work piston driven by the fluid for deriving a useful work output. The work piston pumps a hydraulic fluid and a hydraulic control valve is connected in line with the hydraulic output conduit such that the flow of hydraulic fluid may be restricted to any desired degree or stopped altogether. The work piston can therefore be controlled by means of a controller device independently from the movement of the displacer such that a variety of engine cycles can be obtained for optimum engine efficiency under varying load conditions. While a Stirling engine cycle is particularly contemplated, other engine cycles may be obtained by controlling the movement of the displacer and work pistons. Also disclosed are a working gas recovery system for controlling leakage of working gas from the displacer chamber, and a compound work piston arrangement for preventing leakage of hydraulic fluid around the work piston into the displacer chamber.

  8. Cycle time control of an onboard oxygen generation system.

    PubMed

    Beaman, J J; Wang, S Y; Masada, G Y

    1987-12-01

    The outlet oxygen concentration of an onboard oxygen generation system (OBOGS) is controlled in this study by varying the cycle time of a pressure swing adsorption process. The control of the oxygen concentration is highly desirable since both high and low concentrations of oxygen can cause physiological problems. This cycle time control method can be easily implemented using a DC motor and a simple electronic controller. The physiological requirements recommended for high-performance tactical aircraft can be met by this method with either an open-loop or closed-loop configuration. The open-loop configuration requires the measurement of crew breathing flowrate and cabin pressure. The closed-loop configuration requires an additional measurement of oxygen concentration, but it has the advantage of being more adaptive to system variability during setup and operation. The method in either configuration requires very little adjustment and setup time in order to meet the specifications.

  9. Tectonic control of coastal onlap cycles, southwest Washington

    SciTech Connect

    Armentrout, J.M.

    1987-05-01

    Local coastal onlap and paleobiobathymetric curves for 14 sections define three Cenozoic depositional onlap-offlap cycles separated by regionally significant unconformities. A paleoclimatic curve for western Oregon and Washington, based on paleoecologic data sets, demonstrates that the local transgressions are coincident with cool climates and the regressions with warm climates, and are therefore not driven by glacioeustatic cycles. Comparison of the local coastal onlap and paleobiobathymetric curves with the global Cenozoic Cycle Chart (modified Exxon Sea Level Chart - May, 1986) further demonstrates the uniqueness of the western Washington curves. The global Cenozoic cycle Chart curve represents coastal onlap and sea level curves based on integration of both climate and tectonic variations. The non-parallel cycle pattern for southwest Washington suggests a unique tectonically forced system. Evidence derived from stratigraphic sequences, igneous rock geochemistry, radiometric dating, remnant magnetic patterns, sandstone provenance studies, and paleogeographic reconstructions is used to identify the tectonic events controlling the local depositional cycles. The principal events are (1) middle Eocene accretion of a seamount chain; (2) early-late Eocene westward relocation of subduction; (3) late Eocene onset of Cascade arc volcanism; (4) late-early Miocene plate readjustment due to back-arc extension in the Columbia River Plateau and Great Basin; and (5) late Pliocene to early Pleistocene northeast compression forced by continued subduction of remnants of the Kula Plate beneath North America.

  10. Cell cycle control, checkpoint mechanisms, and genotoxic stress.

    PubMed Central

    Shackelford, R E; Kaufmann, W K; Paules, R S

    1999-01-01

    The ability of cells to maintain genomic integrity is vital for cell survival and proliferation. Lack of fidelity in DNA replication and maintenance can result in deleterious mutations leading to cell death or, in multicellular organisms, cancer. The purpose of this review is to discuss the known signal transduction pathways that regulate cell cycle progression and the mechanisms cells employ to insure DNA stability in the face of genotoxic stress. In particular, we focus on mammalian cell cycle checkpoint functions, their role in maintaining DNA stability during the cell cycle following exposure to genotoxic agents, and the gene products that act in checkpoint function signal transduction cascades. Key transitions in the cell cycle are regulated by the activities of various protein kinase complexes composed of cyclin and cyclin-dependent kinase (Cdk) molecules. Surveillance control mechanisms that check to ensure proper completion of early events and cellular integrity before initiation of subsequent events in cell cycle progression are referred to as cell cycle checkpoints and can generate a transient delay that provides the cell more time to repair damage before progressing to the next phase of the cycle. A variety of cellular responses are elicited that function in checkpoint signaling to inhibit cyclin/Cdk activities. These responses include the p53-dependent and p53-independent induction of Cdk inhibitors and the p53-independent inhibitory phosphorylation of Cdk molecules themselves. Eliciting proper G1, S, and G2 checkpoint responses to double-strand DNA breaks requires the function of the Ataxia telangiectasia mutated gene product. Several human heritable cancer-prone syndromes known to alter DNA stability have been found to have defects in checkpoint surveillance pathways. Exposures to several common sources of genotoxic stress, including oxidative stress, ionizing radiation, UV radiation, and the genotoxic compound benzo[a]pyrene, elicit cell cycle

  11. Calcium constrains plant control over forest ecosystem nitrogen cycling.

    PubMed

    Groffman, Peter M; Fisk, Melany C

    2011-11-01

    Forest ecosystem nitrogen (N) cycling is a critical controller of the ability of forests to prevent the movement of reactive N to receiving waters and the atmosphere and to sequester elevated levels of atmospheric carbon dioxide (CO2). Here we show that calcium (Ca) constrains the ability of northern hardwood forest trees to control the availability and loss of nitrogen. We evaluated soil N-cycling response to Ca additions in the presence and absence of plants and observed that when plants were present, Ca additions "tightened" the ecosystem N cycle, with decreases in inorganic N levels, potential net N mineralization rates, microbial biomass N content, and denitrification potential. In the absence of plants, Ca additions induced marked increases in nitrification (the key process controlling ecosystem N losses) and inorganic N levels. The observed "tightening" of the N cycle when Ca was added in the presence of plants suggests that the capacity of forests to absorb elevated levels of atmospheric N and CO2 is fundamentally constrained by base cations, which have been depleted in many areas of the globe by acid rain and forest harvesting.

  12. New algorithm to control a cycle ergometer using electrical stimulation.

    PubMed

    Petrofsky, J S

    2003-01-01

    Data were collected from four male subjects to determine the relationships between load, speed and muscle use during cycle ergometry. These data were then used to construct equations to govern the stimulation of muscle in paralysed individuals, during cycle ergometry induced by functional electrical stimulation (FES) of the quadriceps, gluteus maximus and hamstring muscles. The algorithm was tested on four subjects who were paralysed owing to a complete spinal cord injury between T4 and T11. Using the multivariate equation, the control of movement was improved, and work was accomplished that was double (2940 Nm min(-1) compared with 5880 Nm min(-1)) that of traditional FES cycle ergometry, when muscle stimulation was also controlled by electrical stimulation. Stress on the body, assessed by cardiac output, was increased almost two-fold during maximum work with the new algorithm (81 min(-1) compared with 15 l min(-1) with the new algorithm). These data support the concept that the limitation to workload that a person can achieve on FES cycle ergometry is in the control equations and not in the paralysed muscle.

  13. Transpiration during life cycle in controlled wheat growth

    NASA Technical Reports Server (NTRS)

    Volk, Tyler; Rummel, John D.

    1989-01-01

    A previously-developed model of wheat growth, designed for convenient incorporation into system-level models of advanced space life support systems is described. The model is applied to data from an experiment that grew wheat under controlled conditions and measured fresh biomass and cumulated transpiration as a function of time. The adequacy of modeling the transpiration as proportional to the inedible biomass, and an age factor which varies during the life cycle, are examined. Results indicate that during the main phase of vegetative growth in the first half of the life cycle, the rate of transpiration per unit mass of inedible biomass is more than double the rate during the phase of grain development and maturation during latter half of the life cycle.

  14. Patterns and controls on nitrogen cycling of biological soil crusts

    USGS Publications Warehouse

    Barger, Nichole N.; Zaady, Eli; Weber, Bettina; Garcia-Pichel, Ferran; Belnap, Jayne

    2016-01-01

    Biocrusts play a significant role in the nitrogen [N ] cycle within arid and semi-arid ecosystems, as they contribute major N inputs via biological fixation and dust capture, harbor internal N transformation processes, and direct N losses via N dissolved, gaseous and erosional loss processes (Fig. 1). Because soil N availability in arid and semi-arid ecosystems is generally low and may limit net primary production (NPP), especially during periods when adequate water is available, understanding the mechanisms and controls of N input and loss pathways in biocrusts is critically important to our broader understanding of N cycling in dryland environments. In particular, N cycling by biocrusts likely regulates short-term soil N availability to support vascular plant growth, as well as long-term N accumulation and maintenance of soil fertility. In this chapter, we review the influence of biocrust nutrient input, internal cycling, and loss pathways across a range of biomes. We examine linkages between N fixation capabilities of biocrust organisms and spatio-temporal patterns of soil N availability that may influence the longer-term productivity of dryland ecosystems. Lastly, biocrust influence on N loss pathways such as N gas loss, leakage of N compounds from biocrusts, and transfer in wind and water erosion are important to understand the maintenance of dryland soil fertility over longer time scales. Although great strides have been made in understanding the influence of biocrusts on ecosystem N cycling, there are important knowledge gaps in our understanding of the influence of biocrusts on ecosystem N cycling that should be the focus of future studies. Because work on the interaction of N cycling and biocrusts was reviewed in Belnap and Lange (2003), this chapter will focus primarily on research findings that have emerged over the last 15 years (2000-2015).

  15. Transpiration during life cycle in controlled wheat growth

    NASA Technical Reports Server (NTRS)

    Volk, Tyler; Rummel, John D.

    1990-01-01

    A previously developed model of wheat growth, designed for convenient incorporation into system level models of advanced space life support systems is described. The model is applied to data from an experiment that grew wheat under controlled conditions and measured fresh biomass and cumulated transpiration as a function of time. The adequacy of modeling the transpiration as proportional to the inedible biomass and an age factor that varies during the life cycle are discussed.

  16. On controlling networks of limit-cycle oscillators

    NASA Astrophysics Data System (ADS)

    Skardal, Per Sebastian; Arenas, Alex

    2016-09-01

    The control of network-coupled nonlinear dynamical systems is an active area of research in the nonlinear science community. Coupled oscillator networks represent a particularly important family of nonlinear systems, with applications ranging from the power grid to cardiac excitation. Here, we study the control of network-coupled limit cycle oscillators, extending the previous work that focused on phase oscillators. Based on stabilizing a target fixed point, our method aims to attain complete frequency synchronization, i.e., consensus, by applying control to as few oscillators as possible. We develop two types of controls. The first type directs oscillators towards larger amplitudes, while the second does not. We present numerical examples of both control types and comment on the potential failures of the method.

  17. Cell Cycle Control by a Minimal Cdk Network

    PubMed Central

    Gérard, Claude; Tyson, John J.; Coudreuse, Damien; Novák, Béla

    2015-01-01

    In present-day eukaryotes, the cell division cycle is controlled by a complex network of interacting proteins, including members of the cyclin and cyclin-dependent protein kinase (Cdk) families, and the Anaphase Promoting Complex (APC). Successful progression through the cell cycle depends on precise, temporally ordered regulation of the functions of these proteins. In light of this complexity, it is surprising that in fission yeast, a minimal Cdk network consisting of a single cyclin-Cdk fusion protein can control DNA synthesis and mitosis in a manner that is indistinguishable from wild type. To improve our understanding of the cell cycle regulatory network, we built and analysed a mathematical model of the molecular interactions controlling the G1/S and G2/M transitions in these minimal cells. The model accounts for all observed properties of yeast strains operating with the fusion protein. Importantly, coupling the model’s predictions with experimental analysis of alternative minimal cells, we uncover an explanation for the unexpected fact that elimination of inhibitory phosphorylation of Cdk is benign in these strains while it strongly affects normal cells. Furthermore, in the strain without inhibitory phosphorylation of the fusion protein, the distribution of cell size at division is unusually broad, an observation that is accounted for by stochastic simulations of the model. Our approach provides novel insights into the organization and quantitative regulation of wild type cell cycle progression. In particular, it leads us to propose a new mechanistic model for the phenomenon of mitotic catastrophe, relying on a combination of unregulated, multi-cyclin-dependent Cdk activities. PMID:25658582

  18. Method for Controlling Space Transportation System Life Cycle Costs

    NASA Technical Reports Server (NTRS)

    McCleskey, Carey M.; Bartine, David E.

    2006-01-01

    A structured, disciplined methodology is required to control major cost-influencing metrics of space transportation systems during design and continuing through the test and operations phases. This paper proposes controlling key space system design metrics that specifically influence life cycle costs. These are inclusive of flight and ground operations, test, and manufacturing and infrastructure. The proposed technique builds on today's configuration and mass properties control techniques and takes on all the characteristics of a classical control system. While the paper does not lay out a complete math model, key elements of the proposed methodology are explored and explained with both historical and contemporary examples. Finally, the paper encourages modular design approaches and technology investments compatible with the proposed method.

  19. Hydromorphological control of nutrient cycling in complex river floodplain systems

    NASA Astrophysics Data System (ADS)

    Hein, T.; Bondar-Kunze, E.; Felkl, M.; Habersack, H.; Mair, M.; Pinay, G.; Tritthart, M.; Welti, N.

    2009-04-01

    Riparian zones and floodplains are key components within river ecosystems controlling nutrient cycling by promoting transformation processes and thus, act as biogeochemical hot spots. The intensity of these processes depends on the exchange conditions (the connectivity) with the main channel and the morphological setting of the water bodies. At the landscape scale, three interrelated principles of hydromorphological dynamics can be formulated regarding the cycling and transfer of carbon and nutrients in large rivers ecosystems: a) The mode of carbon and nutrient delivery affects ecosystem functioning; b) Increasing residence time and contact area impact nutrient transformation; c) Floods and droughts are natural events that strongly influence pathways of carbon and nutrient cycling. These three principles of hydromorphological dynamics control the nutrient uptake and retention and are linked over different temporal and spatial scales. All three factors can be strongly affected by natural disturbances or anthropogenic impacts, through a change in either the water regime or the geomorphologic setting of the river valley. Any change in natural water regimes will affect the biogeochemistry of riparian zones and floodplains as well as their ability to cycle and mitigate nutrient fluxes originating from upstream and/or upslope. Especially these areas have been altered by river regulation and land use changes over the last 200 years leading to the deterioration of the functioning of these compartments within the riverine landscape. The resulting deficits have prompted rehabilitation and restoration measures aiming to increase the spatial heterogeneity, the complexity, of these ecosystems. Yet, a more integrated approach is needed considering the present status of nutrient dynamics and the effects of restoration measures at different scales. The present paper analyses the effects of river side-arm restoration on ecosystem functions within the side-arm and highlights

  20. Cell cycle control of DNA joint molecule resolution.

    PubMed

    Wild, Philipp; Matos, Joao

    2016-06-01

    The establishment of stable interactions between chromosomes underpins vital cellular processes such as recombinational DNA repair and bipolar chromosome segregation. On the other hand, timely disengagement of persistent connections is necessary to assure efficient partitioning of the replicated genome prior to cell division. Whereas great progress has been made in defining how cohesin-mediated chromosomal interactions are disengaged as cells prepare to undergo chromosome segregation, little is known about the metabolism of DNA joint molecules (JMs), generated during the repair of chromosomal lesions. Recent work on Mus81 and Yen1/GEN1, two conserved structure-selective endonucleases, revealed unforeseen links between JM-processing and cell cycle progression. Cell cycle kinases and phosphatases control Mus81 and Yen1/GEN1 to restrain deleterious JM-processing during S-phase, while safeguarding chromosome segregation during mitosis.

  1. CBC Control Panel (Closed Brayton Cycle Control System) v 1.0

    2012-09-13

    The CBC Control Panel is a LabviewTM Virtual Interface program that performs data acquisition, displays this data (over 100 channels), and provides control mechanisms for Closed Brayton Cycle (CBC) power conversion systems. The Program uses a state point control method that transitions the CBC from an IDLE/OFF state to RUNNING state, to SHUTDOWN, and ultimately bac~ to IDLE/OFF. During each state a set of rules control the behavior of the machine.

  2. Model Predictive Control of Integrated Gasification Combined Cycle Power Plants

    SciTech Connect

    B. Wayne Bequette; Priyadarshi Mahapatra

    2010-08-31

    The primary project objectives were to understand how the process design of an integrated gasification combined cycle (IGCC) power plant affects the dynamic operability and controllability of the process. Steady-state and dynamic simulation models were developed to predict the process behavior during typical transients that occur in plant operation. Advanced control strategies were developed to improve the ability of the process to follow changes in the power load demand, and to improve performance during transitions between power levels. Another objective of the proposed work was to educate graduate and undergraduate students in the application of process systems and control to coal technology. Educational materials were developed for use in engineering courses to further broaden this exposure to many students. ASPENTECH software was used to perform steady-state and dynamic simulations of an IGCC power plant. Linear systems analysis techniques were used to assess the steady-state and dynamic operability of the power plant under various plant operating conditions. Model predictive control (MPC) strategies were developed to improve the dynamic operation of the power plants. MATLAB and SIMULINK software were used for systems analysis and control system design, and the SIMULINK functionality in ASPEN DYNAMICS was used to test the control strategies on the simulated process. Project funds were used to support a Ph.D. student to receive education and training in coal technology and the application of modeling and simulation techniques.

  3. Lithium-Ion Battery Cycling for Magnetism Control.

    PubMed

    Zhang, Qingyun; Luo, Xi; Wang, Luning; Zhang, Lifang; Khalid, Bilal; Gong, Jianghong; Wu, Hui

    2016-01-13

    Magnetization and electric-field coupling is fundamentally interesting and important. Specifically, current- or voltage-driven magnetization switching at room temperature is highly desirable from scientific and technological viewpoints. Herein, we demonstrate that magnetization can be controlled via the discharge-charge cycling of a lithium-ion battery (LIB) with rationally designed electrode nanomaterials. Reversible manipulation of magnetism over 3 orders of magnitude was achieved by controlling the lithiation/delithiation of a nanoscale α-Fe2O3-based electrode. The process was completed rapidly under room-temperature conditions. Our results indicate that in addition to energy storage LIBs, which have been under continuous development for several decades, provide exciting opportunities for the multireversible magnetization of magnetic fields.

  4. ASDTIC duty-cycle control for power converters

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Schoenfeld, A. D.

    1972-01-01

    The application of analog signal to discrete interval converter (ASDTIC), a hybrid micromodule, two loop control subsystem, to a switching, stepdown dc to dc converter is described. The power circuitry, interface and ASDTIC subsystems used in this switching regulator were developed to exhibit the improved regulation, transient performance, regulator stability and freedom from the effects of variations in parts characteristics due to environmental changes and aging. ASDTIC can be used with other types of power circuits that use duty-cycle control techniques by simple changes in the interface subsystem. The circuitry and performance characteristics of a +10V dc switching converter as well as that of the ASDTIC micromodule are described. Realization of the ASDTIC hybrid micromodule has been accomplished with a hermetically sealed, beam-lead, bonded/deposited nichrome thin film resistors, discrete capacitors and integrated circuits on dilithic, glazed alumina substrates using 22 feed through terminals in an integrated package.

  5. A Feasibility Study of Fuzzy FES Controller Based on Cycle-to-Cycle Control: An Experimental Test of Knee Extension Control

    NASA Astrophysics Data System (ADS)

    Watanabe, Takashi; Masuko, Tomoya; Arifin, Achmad; Yoshizawa, Makoto

    Functional Electrical Stimulation (FES) can be effective in assisting or restoring paralyzed motor functions. The purpose of this study is to examine experimentally the fuzzy controller based on cycle-to-cycle control for FES-induced gait. A basic experimental test was performed on controlling maximum knee extension angle with normal subjects. In most of control trials, the joint angle was controlled well compensating changes in muscle responses to electrical stimulation. The results show that the fuzzy controller would be practical in clinical applications of gait control by FES. An automatic parameter tuning would be required practically for quick responses in reaching the target and in compensating the change in muscle responses without causing oscillating responses.

  6. Environmental controls on microbial community cycling in modern marine stromatolites

    NASA Astrophysics Data System (ADS)

    Bowlin, Emily M.; Klaus, James S.; Foster, Jamie S.; Andres, Miriam S.; Custals, Lillian; Reid, R. Pamela

    2012-07-01

    Living stromatolites on the margins of Exuma Sound, Bahamas, are the only examples of modern stromatolites forming in open marine conditions similar to those that may have existed on Precambrian platforms. Six microbial mat types have previously been documented on the surfaces of stromatolites along the eastern side of Highborne Cay (Schizothrix, Solentia, heterotrophic biofilm, stalked diatom, tube diatom and Phormidium mats). Cycling of these communities create laminae with distinct microstructures. Subsurface laminae thus represent a chronology of former surface mats. The present study documents the effects of environmental factors on surface microbial communities of modern marine stromatolites and identifies potential causes of microbial mat cycling. Mat type and burial state at 43 markers along a stromatolitic reef on the margin of Highborne Cay were monitored over a two-year period (2005-2006). Key environmental parameters (i.e., temperature, light, wind, water chemistry) were also monitored. Results indicated that the composition of stromatolite surface mats and transitions from one mat type to another are controlled by both seasonal and stochastic events. All six stromatolite mat communities at Highborne Cay showed significant correlations with water temperature. Heterotrophic biofilms, Solentia, stalked diatom and Phormidium mats showed positive correlations with temperature, whereas Schizothrix and tube diatom communities showed negative correlations. A significant correlation with light (photosynthetically active radiation, PAR) was detected only for the heterotrophic biofilm community. No significant correlations were found between mat type and the monitored wind intensity data, but field observations indicated that wind-related events such as storms and sand abrasion play important roles in the transitions from one mat type to another. An integrated model of stromatolite mat community cycling is developed that includes both predictable seasonal

  7. Long-term litter decomposition controlled by manganese redox cycling.

    PubMed

    Keiluweit, Marco; Nico, Peter; Harmon, Mark E; Mao, Jingdong; Pett-Ridge, Jennifer; Kleber, Markus

    2015-09-22

    Litter decomposition is a keystone ecosystem process impacting nutrient cycling and productivity, soil properties, and the terrestrial carbon (C) balance, but the factors regulating decomposition rate are still poorly understood. Traditional models assume that the rate is controlled by litter quality, relying on parameters such as lignin content as predictors. However, a strong correlation has been observed between the manganese (Mn) content of litter and decomposition rates across a variety of forest ecosystems. Here, we show that long-term litter decomposition in forest ecosystems is tightly coupled to Mn redox cycling. Over 7 years of litter decomposition, microbial transformation of litter was paralleled by variations in Mn oxidation state and concentration. A detailed chemical imaging analysis of the litter revealed that fungi recruit and redistribute unreactive Mn(2+) provided by fresh plant litter to produce oxidative Mn(3+) species at sites of active decay, with Mn eventually accumulating as insoluble Mn(3+/4+) oxides. Formation of reactive Mn(3+) species coincided with the generation of aromatic oxidation products, providing direct proof of the previously posited role of Mn(3+)-based oxidizers in the breakdown of litter. Our results suggest that the litter-decomposing machinery at our coniferous forest site depends on the ability of plants and microbes to supply, accumulate, and regenerate short-lived Mn(3+) species in the litter layer. This observation indicates that biogeochemical constraints on bioavailability, mobility, and reactivity of Mn in the plant-soil system may have a profound impact on litter decomposition rates.

  8. Long-term litter decomposition controlled by manganese redox cycling

    PubMed Central

    Keiluweit, Marco; Nico, Peter; Harmon, Mark E.; Mao, Jingdong; Pett-Ridge, Jennifer; Kleber, Markus

    2015-01-01

    Litter decomposition is a keystone ecosystem process impacting nutrient cycling and productivity, soil properties, and the terrestrial carbon (C) balance, but the factors regulating decomposition rate are still poorly understood. Traditional models assume that the rate is controlled by litter quality, relying on parameters such as lignin content as predictors. However, a strong correlation has been observed between the manganese (Mn) content of litter and decomposition rates across a variety of forest ecosystems. Here, we show that long-term litter decomposition in forest ecosystems is tightly coupled to Mn redox cycling. Over 7 years of litter decomposition, microbial transformation of litter was paralleled by variations in Mn oxidation state and concentration. A detailed chemical imaging analysis of the litter revealed that fungi recruit and redistribute unreactive Mn2+ provided by fresh plant litter to produce oxidative Mn3+ species at sites of active decay, with Mn eventually accumulating as insoluble Mn3+/4+ oxides. Formation of reactive Mn3+ species coincided with the generation of aromatic oxidation products, providing direct proof of the previously posited role of Mn3+-based oxidizers in the breakdown of litter. Our results suggest that the litter-decomposing machinery at our coniferous forest site depends on the ability of plants and microbes to supply, accumulate, and regenerate short-lived Mn3+ species in the litter layer. This observation indicates that biogeochemical constraints on bioavailability, mobility, and reactivity of Mn in the plant–soil system may have a profound impact on litter decomposition rates. PMID:26372954

  9. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Upton, Lisa

    2013-01-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow can modulate the amplitude of the following sunspot cycle through its influence on the Sun's polar fields.

  10. Space Transportation Systems Life Cycle Cost Assessment and Control

    NASA Technical Reports Server (NTRS)

    Robinson, John W.; Rhodes, Russell E.; Zapata, Edgar; Levack, Daniel J. H.; Donahue, Benjaamin B.; Knuth, William

    2008-01-01

    Civil and military applications of space transportation have been pursued for just over 50 years and there has been, and still is, a need for safe, dependable, affordable, and sustainable space transportation systems. Fully expendable and partially reusable space transportation systems have been developed and put in operation that have not adequately achieved this need. Access to space is technically achievable, but presently very expensive and will remain so until there is a breakthrough in the way we do business. Since 1991 the national Space Propulsion Synergy Team (SPST) has reviewed and assessed the lessons learned from the major U.S. space programs of the past decades focusing on what has been learned from the assessment and control of Life Cycle Cost (LCC) from these systems. This paper presents the results of a selected number of studies and analyses that have been conducted by the SPST addressing the need, as well as the solutions, for improvement in LCC. The major emphasis of the SPST processes is on developing the space transportation system requirements first (up front). These requirements must include both the usual system flight performance requirements and also the system functional requirements, including the infrastructure on Earth's surface, in-space and on the Moon and Mars surfaces to determine LCC. This paper describes the development of specific innovative engineering and management approaches and processes. This includes a focus on flight hardware maturity for reliability, ground operations approaches, and business processes between contractor and government organizations. A major change in program/project cost control is being proposed by the SPST to achieve a sustainable space transportation system LCC - controlling cost as a program metric in addition to the existing practice of controlling performance and weight. Without a firm requirement and methodically structured cost control, it is unlikely that an affordable and sustainable space

  11. Fuzzy FES controller using cycle-to-cycle control for repetitive movement training in motor rehabilitation. Experimental tests with wireless system.

    PubMed

    Miura, Naoto; Watanabe, Takashi; Sugimoto, Satoru; Seki, Kazunori; Kanai, Hiroshi

    2011-01-01

    A prototype of wireless surface electrical stimulation system combined with the fuzzy FES controller was developed for rehabilitation training with functional electrical stimulation (FES). The developed FES system has three features for rehabilitation training: small-sized electrical stimulator for surface FES, wireless connection between controller and stimulators, and between controller and sensors, and the fuzzy FES controller based on the cycle-to-cycle control for repetitive training. The developed stimulator could generate monophasic or biphasic high voltage stimulus pulse and could output stimulation pulses continuously more than 20 hours with 4 AAA batteries. The developed system was examined with neurologically intact subjects and hemiplegic subjects in knee joint control. The maximum knee joint angle was controlled by regulating burst duration of stimulation pulses by the fuzzy controller. In the results of two experiments of knee extension angle control and knee flexion and extension angle control, the maximum angles reached their targets within small number of cycles and were controlled stably in the stimulation cycles after reaching the target. The fuzzy FES controller based on the cycle-to-cycle control worked effectively to reach the target angle and to compensate difference in muscle properties between subjects. The developed wireless surface FES system would be practical in clinical applications of repetitive execution of similar movements of the limbs for motor rehabilitation with FES.

  12. Fuzzy FES controller using cycle-to-cycle control for repetitive movement training in motor rehabilitation. Experimental tests with wireless system.

    PubMed

    Miura, Naoto; Watanabe, Takashi; Sugimoto, Satoru; Seki, Kazunori; Kanai, Hiroshi

    2011-01-01

    A prototype of wireless surface electrical stimulation system combined with the fuzzy FES controller was developed for rehabilitation training with functional electrical stimulation (FES). The developed FES system has three features for rehabilitation training: small-sized electrical stimulator for surface FES, wireless connection between controller and stimulators, and between controller and sensors, and the fuzzy FES controller based on the cycle-to-cycle control for repetitive training. The developed stimulator could generate monophasic or biphasic high voltage stimulus pulse and could output stimulation pulses continuously more than 20 hours with 4 AAA batteries. The developed system was examined with neurologically intact subjects and hemiplegic subjects in knee joint control. The maximum knee joint angle was controlled by regulating burst duration of stimulation pulses by the fuzzy controller. In the results of two experiments of knee extension angle control and knee flexion and extension angle control, the maximum angles reached their targets within small number of cycles and were controlled stably in the stimulation cycles after reaching the target. The fuzzy FES controller based on the cycle-to-cycle control worked effectively to reach the target angle and to compensate difference in muscle properties between subjects. The developed wireless surface FES system would be practical in clinical applications of repetitive execution of similar movements of the limbs for motor rehabilitation with FES. PMID:21767134

  13. Control of the respiratory cycle in conscious humans.

    PubMed

    Rafferty, G F; Gardner, W N

    1996-10-01

    We studied in conscious humans the relative strength of mechanisms controlling timing and drive components of the respiratory cycle around their resting set points. A system of auditory feedback with end-tidal PCO2 held constant in mild hyperoxia via an open circuit was used to induce subjects independently to change inspiratory time (TI) and tidal volume (VTI) over a wide range above and below the resting values for every breath for up to 1 h. Four protocols were studied in various levels of hypercapnia (1-5% inspired CO2). We found that TI (and expiratory time) could be changed over a wide range (1.17 - 2.86 s, P < 0.01 for TI) and VTI increased by > or = 500 ml (P < 0.01) without difficulty. However, in no protocol was it possible to decrease VTI below the free-breathing resting value in response to reduction of auditory feedback thresholds by up to 600 ml. This applied at all levels of chemical drive studied, with resting VTI values varying from 1.06 to 1.74 liters. When reduction in VTI was forced by the more "programmed" procedure of isocapnic panting, end-expiratory of volume was sacrificed to ensure that peak tidal volume reached a fixed absolute lung volume. These results suggest that the imperative for control of resting breathing is to prevent reduction of VTI below the level dictated by the prevailing chemical drive, presumably to sustain metabolic requirements of the body, whereas respiratory timing is weakly controlled consistent with the needs for speech and other nonmetabolic functions of breathing. PMID:8904595

  14. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Upton, Lisa

    2013-01-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow should also modulate the amplitude of the following sunspot cycle through its influence on the Sun's polar fields. The observational evidence and the theoretical consequences (similar to those of Cameron and Schussler (2012)) will be described.

  15. Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes

    NASA Astrophysics Data System (ADS)

    Hathaway, David H.; Upton, L.

    2013-07-01

    We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow should also modulate the amplitude of the following sunspot cycle through its influence on the Sun’s polar fields. The observational evidence and the theoretical consequences (similar to those of Cameron and Schussler (2012)) will be described. Komm, Howard, and Harvey (1993) Solar Phys. 147, 207. Cameron and Schussler (2012) Astron. Astrophys. 548, A57.

  16. Controlled natural cycle IVF with antagonist use and blastocyst transfer.

    PubMed

    Trokoudes, K M; Minbattiwalla, M B; Kalogirou, L; Pantelides, K; Mitsingas, P; Sokratous, A; Chrysanthou, A; Fasouliotis, S J

    2005-12-01

    A method of controlled natural cycle IVF (CONCIVF) was sought to provide simpler and shorter treatment without the risks of ovarian hyperstimulation syndrome and multiple pregnancies. A total of 138 couples with normal ovulation and normal sperm parameters, in whom the women were <40 years old, were the candidates for this study. Gonadotrophin-releasing hormone antagonist was used before human chorionic gonadotrophin (HCG) administration if LH increased to a concentration of 10 mIU/ml before HCG injection. Treatment was initiated at > or =16 mm follicular growth and at oestradiol concentrations > or =400 pmol/l with 5000 IU HCG induction. All the embryos were cultured to the blastocyst stage and transferred only if they reached early or advanced blastulation. A total of 126 patients underwent oocyte retrieval. In 102 cases, one oocyte was retrieved; 95% of the oocytes fertilized, 99% cleaved and 47.9% achieved the blastocyst stage. The implantation rate per blastocyst transfer was 53.3% and the live-birth rate per embryo transfer was 40%. Therefore, CONCIVF with blastocyst transfer gives acceptable blastocyst development and implantation rates without the long- or short-term side effects of ovulation induction. PMID:16417731

  17. Cell cycle controls stress response and longevity in C. elegans

    PubMed Central

    Dottermusch, Matthias; Lakner, Theresa; Peyman, Tobias; Klein, Marinella; Walz, Gerd; Neumann-Haefelin, Elke

    2016-01-01

    Recent studies have revealed a variety of genes and mechanisms that influence the rate of aging progression. In this study, we identified cell cycle factors as potent regulators of health and longevity in C. elegans. Focusing on the cyclin-dependent kinase 2 (cdk-2) and cyclin E (cye-1), we show that inhibition of cell cycle genes leads to tolerance towards environmental stress and longevity. The reproductive system is known as a key regulator of longevity in C. elegans. We uncovered the gonad as the central organ mediating the effects of cell cycle inhibition on lifespan. In particular, the proliferating germ cells were essential for conferring longevity. Steroid hormone signaling and the FOXO transcription factor DAF-16 were required for longevity associated with cell cycle inhibition. Furthermore, we discovered that SKN-1 (ortholog of mammalian Nrf proteins) activates protective gene expression and induces longevity when cell cycle genes are inactivated. We conclude that both, germline absence and inhibition through impairment of cell cycle machinery results in longevity through similar pathways. In addition, our studies suggest further roles of cell cycle genes beyond cell cycle progression and support the recently described connection of SKN-1/Nrf to signals deriving from the germline. PMID:27668945

  18. Cell cycle control by oscillating regulatory proteins in Caulobacter crescentus.

    PubMed

    Holtzendorff, Julia; Reinhardt, Jens; Viollier, Patrick H

    2006-04-01

    Significant strides have been made in recent years towards understanding the molecular basis of cell cycle progression in the model bacterium Caulobacter crescentus. At the heart of cell cycle regulation is a multicomponent transcriptional feedback loop, governing the production of successive regulatory waves or pulses of at least three master regulatory proteins. These oscillating master regulators direct the execution of phase-specific events and, importantly, through intrinsic genetic switches not only determine the length of a given phase, but also provide the driving force that catapults the cell into the next stage of the cell cycle. The genetic switches act as fail safe mechanisms that prevent the cell cycle from relapsing and thus govern the ordered production and the periodicity of these regulatory waves. Here, we detail how the master regulators CtrA, GcrA and DnaA coordinate cell cycle progression and polar development in Caulobacter. PMID:16547950

  19. Cell cycle control by oscillating regulatory proteins in Caulobacter crescentus.

    PubMed

    Holtzendorff, Julia; Reinhardt, Jens; Viollier, Patrick H

    2006-04-01

    Significant strides have been made in recent years towards understanding the molecular basis of cell cycle progression in the model bacterium Caulobacter crescentus. At the heart of cell cycle regulation is a multicomponent transcriptional feedback loop, governing the production of successive regulatory waves or pulses of at least three master regulatory proteins. These oscillating master regulators direct the execution of phase-specific events and, importantly, through intrinsic genetic switches not only determine the length of a given phase, but also provide the driving force that catapults the cell into the next stage of the cell cycle. The genetic switches act as fail safe mechanisms that prevent the cell cycle from relapsing and thus govern the ordered production and the periodicity of these regulatory waves. Here, we detail how the master regulators CtrA, GcrA and DnaA coordinate cell cycle progression and polar development in Caulobacter.

  20. Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis

    NASA Technical Reports Server (NTRS)

    Ingber, D. E.; Prusty, D.; Sun, Z.; Betensky, H.; Wang, N.

    1995-01-01

    Capillary endothelial cells can be switched between growth and differentiation by altering cell-extracellular matrix interactions and thereby, modulating cell shape. Studies were carried out to determine when cell shape exerts its growth-regulatory influence during cell cycle progression and to explore the role of cytoskeletal structure and mechanics in this control mechanism. When G0-synchronized cells were cultured in basic fibroblast growth factor (FGF)-containing defined medium on dishes coated with increasing densities of fibronectin or a synthetic integrin ligand (RGD-containing peptide), cell spreading, nuclear extension, and DNA synthesis all increased in parallel. To determine the minimum time cells must be adherent and spread on extracellular matrix (ECM) to gain entry into S phase, cells were removed with trypsin or induced to retract using cytochalasin D at different times after plating. Both approaches revealed that cells must remain extended for approximately 12-15 h and hence, most of G1, in order to enter S phase. After this restriction point was passed, normally 'anchorage-dependent' endothelial cells turned on DNA synthesis even when round and in suspension. The importance of actin-containing microfilaments in shape-dependent growth control was confirmed by culturing cells in the presence of cytochalasin D (25-1000 ng ml-1): dose-dependent inhibition of cell spreading, nuclear extension, and DNA synthesis resulted. In contrast, induction of microtubule disassembly using nocodazole had little effect on cell or nuclear spreading and only partially inhibited DNA synthesis. Interestingly, combination of nocodazole with a suboptimal dose of cytochalasin D (100 ng ml-1) resulted in potent inhibition of both spreading and growth, suggesting that microtubules are redundant structural elements which can provide critical load-bearing functions when microfilaments are partially compromised. Similar synergism between nocodazole and cytochalasin D was observed

  1. Global calcite cycling constrained by sediment preservation controls

    NASA Astrophysics Data System (ADS)

    Dunne, John P.; Hales, Burke; Toggweiler, J. R.

    2012-09-01

    We assess the global balance of calcite export through the water column and burial in sediments as it varies regionally. We first drive a comprehensive 1-D model for sediment calcite preservation with globally gridded field observations and satellite-based syntheses. We then reformulate this model into a simpler five-parameter box model, and combine it with algorithms for surface calcite export and water column dissolution for a single expression for the vertical calcite balance. The resulting metamodel is optimized to fit the observed distributions of calcite burial flux. We quantify the degree to which calcite export, saturation state, organic carbon respiration, and lithogenic sedimentation modulate the burial of calcite. We find that 46% of burial and 88% of dissolution occurs in sediments overlain by undersaturated bottom water with sediment calcite burial strongly modulated by surface export. Relative to organic carbon export, we find surface calcite export skewed geographically toward relatively warm, oligotrophic areas dominated by small, prokaryotic phytoplankton. We assess century-scale projected impacts of warming and acidification on calcite export, finding high sensitive to inferred saturation state controls. With respect to long-term glacial cycling, our analysis supports the hypothesis that strong glacial abyssal stratification drives the lysocline toward much closer correspondence with the saturation horizon. Our analysis suggests that, over the transition from interglacial to glacial ocean, a resulting ˜0.029 PgC a-1decrease in deep Atlantic, Indian and Southern Ocean calcite burial leads to slow increase in ocean alkalinity until Pacific mid-depth calcite burial increases to compensate.

  2. Controls on silicon cycling in Southeast Asian rice production systems

    NASA Astrophysics Data System (ADS)

    Klotzbücher, Thimo; Marxen, Anika; Vetterlein, Doris; Jahn, Reinhold

    2013-04-01

    Recent research suggests that silicon (Si) is beneficial for rice plants, i.e., a sufficient Si supply improves their resistance against pests and pathogens and increases the uptake of essential nutrients. Despite its potential importance for rice yields, cycling of Si in rice production systems is poorly studied. We assess plant-available Si (Sipa; determined using acetate extraction) in topsoils (Ap+Arp horizons) and Si uptake by plants at 70 paddy fields managed by local farmers in contrasting regions of Vietnam and the Philippines. First results show that Sipa contents are considerably larger in Philippine (217 ± 100 mg Sipa kg-1 ) than in Vietnamese (32 ± 19 mg Sipa kg-1) paddy soils. Rice straw from the Philippines contains 8.6 ± 0.9 % Si, straw from Vietnam 5.0 ± 1.2 % Si. Laboratory experiments showed that Si is limiting the growth of rice plants in some of the Vietnamese soils. We assume that differences in geo-/ pedologic conditions between Vietnam and the Philippines explain the data. Large Sipa contents in the Philippine soils are due to recent rock formation by active volcanism, hence, by a large Sipa input due to mineral weathering in recent geologic history. In contrast, parent materials of the Vietnamese paddy soils derive from old and highly weathered land surfaces. Hence, our data suggest that geo-/pedologic conditions are the main control for the availability of Si in paddy soils. Currently, we examine the relevance of agricultural practices for small-scale differences in the availability of Si within regions. Inadequate practices, such as removal of rice straw from the fields, might deplete Sipa in paddy soils causing a decrease in rice yields in some regions of Vietnam. We investigate the role of phytoliths (amorphous Si bodies contained in rice straw) as source of Sipa in paddy soils. Our methods include laboratory experiments and the assessment of turnover times of phytoliths in paddy soils; first results will be presented and discussed

  3. Interplay between flagellation and cell cycle control in Caulobacter.

    PubMed

    Ardissone, Silvia; Viollier, Patrick H

    2015-12-01

    The assembly of the flagellum, a sophisticated nanomachine powering bacterial locomotion in liquids and across surfaces, is highly regulated. In the synchronizable α-Proteobacterium Caulobacter crescentus, the flagellum is built at a pre-selected cell pole and flagellar transcript abundance oscillates during the cell cycle. Conserved regulators not only dictate when the transcripts encoding flagellar structural proteins peak, but also those encoding polarization factors. Additionally, post-transcriptional cell cycle cues facilitate flagellar (dis-)assembly at the new cell pole. Because of this regulatory complexity and the power of bacterial genetics, motility is a suitable and simple proxy for dissecting how bacteria implement cell cycle progression and polarity, while also providing clues on how bacteria might decide when and where to display other surface structures. PMID:26476805

  4. Effects of the Menstrual Cycle and Oral Contraception on Singers' Pitch Control

    ERIC Educational Resources Information Center

    La, Filipa M. B.; Sundberg, Johan; Howard, David M.; Sa-Couto, Pedro; Freitas, Adelaide

    2012-01-01

    Purpose: Difficulties with intonation and vibrato control during the menstrual cycle have been reported by singers; however, this phenomenon has not yet been systematically investigated. Method: A double-blind randomized placebo-controlled trial assessing effects of the menstrual cycle and use of a combined oral contraceptive pill (OCP) on pitch…

  5. Evaluation of absorption cycle for space station environmental control system application

    NASA Technical Reports Server (NTRS)

    Sims, W. H.; Oneill, M. J.; Reid, H. C.; Bisenius, P. M.

    1972-01-01

    The study to evaluate an absorption cycle refrigeration system to provide environmental control for the space stations is reported. A zero-gravity liquid/vapor separator was designed and tested. The results were used to design a light-weight, efficient generator for the absorption refrigeration system. It is concluded that absorption cycle refrigeration is feasible for providing space station environmental control.

  6. Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Optical and thermal-fluid evaluation

    DOE PAGESBeta

    Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; Ho, Clifford; Yellowhair, Julius; Dutta, Pradip

    2016-05-30

    In single phase performance and appealing thermo-physical properties supercritical carbon dioxide (s-CO2) make a good heat transfer fluid candidate for concentrating solar power (CSP) technologies. The development of a solar receiver capable of delivering s-CO2 at outlet temperatures ~973 K is required in order to merge CSP and s-CO2 Brayton cycle technologies. A coupled optical and thermal-fluid modeling effort for a tubular receiver is undertaken to evaluate the direct tubular s-CO2 receiver’s thermal performance when exposed to a concentrated solar power input of ~0.3–0.5 MW. Ray tracing, using SolTrace, is performed to determine the heat flux profiles on the receivermore » and computational fluid dynamics (CFD) determines the thermal performance of the receiver under the specified heating conditions. Moreover, an in-house MATLAB code is developed to couple SolTrace and ANSYS Fluent. CFD modeling is performed using ANSYS Fluent to predict the thermal performance of the receiver by evaluating radiation and convection heat loss mechanisms. Understanding the effects of variation in heliostat aiming strategy and flow configurations on the thermal performance of the receiver was achieved through parametric analyses. Finally, a receiver thermal efficiency ~85% was predicted and the surface temperatures were observed to be within the allowable limit for the materials under consideration.« less

  7. Effect of endometrial biopsy on intrauterine insemination outcome in controlled ovarian stimulation cycle

    PubMed Central

    Wadhwa, Leena; Pritam, Amrita; Gupta, Taru; Gupta, Sangeeta; Arora, Sarika; Chandoke, Rajkumar

    2015-01-01

    OBJECTIVE: The objective was to evaluate the effect of endometrial biopsy (EB) on intrauterine insemination (IUI) outcome in controlled ovarian stimulation (COS) cycle. DESIGN: Prospective randomized control study. SETTING: Tertiary care center. MATERIALS AND METHODS: A total of 251 subjects were enrolled in the study. Subjects undergoing COS with IUI were randomly allocated into three groups. Group A: EB was taken between D19 and 24 of the spontaneous menstrual cycles that precedes the fertility treatment and IUI, which was done in next cycle (n = 86). Group B: EB was taken before D6 of the menstrual cycle, and fertility treatment and IUI was done in the same cycle (n = 90). Group C: (control group) no EB in previous 3 cycle (n = 75). MAIN OUTCOME MEASURE: Clinical pregnancy rate (CPR). RESULTS: Clinical pregnancy rate was 19.77%, 31.11%, and 9.3% for Group A, Group B, and Group C, respectively. The results show a highly significant value for the paired t-test of intervention Group B and control Group C of the cases (P = 0.000957). CPR was maximum after first cycle of ovulation induction and IUI following EB scratch in both Groups A and in Group B (P < 0.001). CONCLUSIONS: Endometrial biopsy done in early follicular phase in the same cycle of stimulation with IUI gives better CPR as compared with EB done in the luteal phase of the previous cycle. PMID:26538858

  8. METHOD AND APPARATUS FOR CONTROLLING DIRECT-CYCLE NEUTRONIC REACTORS

    DOEpatents

    Reed, G.A.

    1961-01-10

    A control arrangement is offered for a boiling-water reactor. Boric acid is maintained in the water in the reactor and the amount in the reactor is controlled by continuously removing a portion of the water from the reactor, concentrating the boric acid by evaporating the water therefrom, returning a controlled amount of the acid to the reactor, and simultaneously controlling the water level by varying the rate of spent steam return to the reactor.

  9. Interacting factors in the control of the crustacean molt cycle

    SciTech Connect

    Skinner, D.M.

    1985-01-01

    In order to account for the known phenomena of the crustacean molt cycle, at least six factors must be postulated: a molting hormone (20-OH-ecdysone), a molt-inhibiting hormone (MIH), an anecdysial limb autotomy factor, a proecdysial limb-autotomy factor, a limb growth-inhibiting factor and an exuviation factor. Only the molting hormone and its derivatives have been chemically well defined. The various factors interact in complex ways to maintain not only a coordinated proecdysial period in preparation for exuviation but also a proecdysial period with the flexibility to respond to such interim hazards as the loss of partially regenerated limbs. 79 references, 2 figures, 1 table.

  10. Interacting factors in the control of the crustacean molt cycle

    SciTech Connect

    Skinner, D.M.

    1983-01-01

    In order to account for the known phenomena of the crustacean molt cycle, at least six factors must be postulated: a molting hormone (20-OH-ecdysone), a molt inhibiting hormone (MIH), an anecdysial limb autotomy factor, a proecdysial limb autotomy factor, a limb growth inhibiting factor and an exuviation factor. Only the molting hormone and its derivatives have been chemically well defined. The various factors interact in complex ways to maintain not only a coordinated proecdysial period in preparation for exuviation but also a proecdysial period with the flexibility to respond to such interim hazards as the loss of partially regenerated limbs. 78 references, 2 figures, 1 table.

  11. Characterizing Observed Limit Cycles in the Cassini Main Engine Guidance Control System

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen; Weitl, Raquel M.

    2011-01-01

    The Cassini spacecraft dynamics-related telemetry during long Main Engine (ME) burns has indicated the presence of stable limit cycles between 0.03-0.04 Hz frequencies. These stable limit cycles cause the spacecraft to possess non-zero oscillating rates for extended periods of time. This indicates that the linear ME guidance control system does not model the complete dynamics of the spacecraft. In this study, we propose that the observed limit cycles in the spacecraft dynamics telemetry appear from a stable interaction between the unmodeled nonlinear elements in the ME guidance control system. Many nonlinearities in the control system emerge from translating the linear engine gimbal actuator (EGA) motion into a spacecraft rotation. One such nonlinearity comes from the gear backlash in the EGA system, which is the focus of this paper. The limit cycle characteristics and behavior can be predicted by modeling this gear backlash nonlinear element via a describing function and studying the interaction of this describing function with the overall dynamics of the spacecraft. The linear ME guidance controller and gear backlash nonlinearity are modeled analytically. The frequency, magnitude, and nature of the limit cycle are obtained from the frequency response of the ME guidance controller and nonlinear element. In addition, the ME guidance controller along with the nonlinearity is simulated. The simulation response contains a limit cycle with similar characterstics as predicted analytically: 0.03-0.04 Hz frequency and stable, sustained oscillations. The analytical and simulated limit cycle responses are compared to the flight telemetry for long burns such as the Saturn Orbit Insertion and Main Engine Orbit Trim Maneuvers. The analytical and simulated limit cycle characteristics compare well with the actual observed limit cycles in the flight telemetry. Both have frequencies between 0.03-0.04 Hz and stable oscillations. This work shows that the stable limit cycles occur

  12. Evaluation and Optimization of a Supercritical Carbon Dioxide Power Conversion Cycle for Nuclear Applications

    SciTech Connect

    Edwin A. Harvego; Michael G. McKellar

    2011-05-01

    There have been a number of studies involving the use of gases operating in the supercritical mode for power production and process heat applications. Supercritical carbon dioxide (CO2) is particularly attractive because it is capable of achieving relatively high power conversion cycle efficiencies in the temperature range between 550°C and 750°C. Therefore, it has the potential for use with any type of high-temperature nuclear reactor concept, assuming reactor core outlet temperatures of at least 550°C. The particular power cycle investigated in this paper is a supercritical CO2 Recompression Brayton Cycle. The CO2 Recompression Brayton Cycle can be used as either a direct or indirect power conversion cycle, depending on the reactor type and reactor outlet temperature. The advantage of this cycle when compared to the helium Brayton Cycle is the lower required operating temperature; 550°C versus 850°C. However, the supercritical CO2 Recompression Brayton Cycle requires an operating pressure in the range of 20 MPa, which is considerably higher than the required helium Brayton cycle operating pressure of 8 MPa. This paper presents results of analyses performed using the UniSim process analyses software to evaluate the performance of the supercritical CO2 Brayton Recompression Cycle for different reactor outlet temperatures. The UniSim model assumed a 600 MWt reactor power source, which provides heat to the power cycle at a maximum temperature of between 550°C and 750°C. The UniSim model used realistic component parameters and operating conditions to model the complete power conversion system. CO2 properties were evaluated, and the operating range for the cycle was adjusted to take advantage of the rapidly changing conditions near the critical point. The UniSim model was then optimized to maximize the power cycle thermal efficiency at the different maximum power cycle operating temperatures. The results of the analyses showed that power cycle thermal

  13. Control of sleep by a network of cell cycle genes.

    PubMed

    Afonso, Dinis J S; Machado, Daniel R; Koh, Kyunghee

    2015-01-01

    Sleep is essential for health and cognition, but the molecular and neural mechanisms of sleep regulation are not well understood. We recently reported the identification of TARANIS (TARA) as a sleep-promoting factor that acts in a previously unknown arousal center in Drosophila. tara mutants exhibit a dose-dependent reduction in sleep amount of up to ∼60%. TARA and its mammalian homologs, the Trip-Br (Transcriptional Regulators Interacting with PHD zinc fingers and/or Bromodomains) family of proteins, are primarily known as transcriptional coregulators involved in cell cycle progression, and contain a conserved Cyclin-A (CycA) binding homology domain. We found that tara and CycA synergistically promote sleep, and CycA levels are reduced in tara mutants. Additional data demonstrated that Cyclin-dependent kinase 1 (Cdk1) antagonizes tara and CycA to promote wakefulness. Moreover, we identified a subset of CycA expressing neurons in the pars lateralis, a brain region proposed to be analogous to the mammalian hypothalamus, as an arousal center. In this Extra View article, we report further characterization of tara mutants and provide an extended discussion of our findings and future directions within the framework of a working model, in which a network of cell cycle genes, tara, CycA, and Cdk1, interact in an arousal center to regulate sleep. PMID:26925838

  14. Preliminary tests of a prototype FES control system for cycling wheelchair rehabilitation.

    PubMed

    Watanabe, Takashi; Murakami, Takuya; Handa, Yasunobu

    2013-06-01

    The cycling wheelchair "Profhand" developed by our research group in Japan has been found to be useful in rehabilitation of motor function of lower limbs. It is also expected for rehabilitation of paraplegic subjects to propel the cycling wheelchair by lower limbs controlled by functional electrical stimulation (FES). In this paper, a prototype FES control system for the cycling wheelchair was developed using wireless surface stimulators and wireless inertial sensors and tested with healthy subjects. The stimulation pattern that stimulated the quadriceps femoris and the gluteus maximus at the same time was shown to be effective to propel the Profhand. From the analysis of steady state cycling, it was shown that the cycling speed was smaller and the variation of the speed was larger in FES cycling than those of voluntary cycling. Measured angular velocity of the crank suggested that stimulation timing have to be changed considering delay in muscle response to electrical stimulation and cycling speed in order to improve FES cycling. It was also suggested that angle of the pedal have to be adjusted by controlling ankle joint angle with FES in order to apply force appropriately.

  15. Cycling Versus Continuous Mode In Neuromodulator Programming: A Crossover, Randomized, Controlled Trial.

    PubMed

    Beer, Gwendolyn M; Gurule, Margaret M; Komesu, Yuko M; Qualls, Clifford R; Rogers, Rebecca G

    2016-01-01

    This is a randomized, controlled, blind, crossover trial comparing cycling versus continuous programming of a sacral neuromodulator in women diagnosed with overactive bladder (OAB). At 6 months, treatment order significantly affected Overactive Bladder Questionnaire - Short Form (OABq-SF) symptom scores. The cycling followed by continuous stimulation group had superior OABq-SF scores (p > 0.02). PMID:27501593

  16. SON controls cell-cycle progression by coordinated regulation of RNA splicing.

    PubMed

    Ahn, Eun-Young; DeKelver, Russell C; Lo, Miao-Chia; Nguyen, Tuyet Ann; Matsuura, Shinobu; Boyapati, Anita; Pandit, Shatakshi; Fu, Xiang-Dong; Zhang, Dong-Er

    2011-04-22

    It has been suspected that cell-cycle progression might be functionally coupled with RNA processing. However, little is known about the role of the precise splicing control in cell-cycle progression. Here, we report that SON, a large Ser/Arg (SR)-related protein, is a splicing cofactor contributing to efficient splicing of cell-cycle regulators. Downregulation of SON leads to severe impairment of spindle pole separation, microtubule dynamics, and genome integrity. These molecular defects result from inadequate RNA splicing of a specific set of cell-cycle-related genes that possess weak splice sites. Furthermore, we show that SON facilitates the interaction of SR proteins with RNA polymerase II and other key spliceosome components, suggesting its function in efficient cotranscriptional RNA processing. These results reveal a mechanism for controlling cell-cycle progression through SON-dependent constitutive splicing at suboptimal splice sites, with strong implications for its role in cancer and other human diseases.

  17. Limit-cycle-based control of the myogenic wingbeat rhythm in the fruit fly Drosophila

    PubMed Central

    Bartussek, Jan; Mutlu, A. Kadir; Zapotocky, Martin; Fry, Steven N.

    2013-01-01

    In many animals, rhythmic motor activity is governed by neural limit cycle oscillations under the control of sensory feedback. In the fruit fly Drosophila melanogaster, the wingbeat rhythm is generated myogenically by stretch-activated muscles and hence independently from direct neural input. In this study, we explored if generation and cycle-by-cycle control of Drosophila's wingbeat are functionally separated, or if the steering muscles instead couple into the myogenic rhythm as a weak forcing of a limit cycle oscillator. We behaviourally tested tethered flying flies for characteristic properties of limit cycle oscillators. To this end, we mechanically stimulated the fly's ‘gyroscopic’ organs, the halteres, and determined the phase relationship between the wing motion and stimulus. The flies synchronized with the stimulus for specific ranges of stimulus amplitude and frequency, revealing the characteristic Arnol'd tongues of a forced limit cycle oscillator. Rapid periodic modulation of the wingbeat frequency prior to locking demonstrates the involvement of the fast steering muscles in the observed control of the wingbeat frequency. We propose that the mechanical forcing of a myogenic limit cycle oscillator permits flies to avoid the comparatively slow control based on a neural central pattern generator. PMID:23282849

  18. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    DOE PAGESBeta

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion whenmore » speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.« less

  19. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    SciTech Connect

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion when speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.

  20. Unifying the Gait Cycle in the Control of a Powered Prosthetic Leg

    PubMed Central

    Martin, Anne E.; Gregg, Robert D.

    2015-01-01

    This paper presents a novel control strategy for an above-knee powered prosthetic leg that unifies the entire gait cycle, eliminating the need to switch between controllers during different periods of gait. Current control methods divide the gait cycle into several sequential periods each with independent controllers, resulting in many patient-specific control parameters and switching rules that must be tuned by clinicians. Having a single controller could reduce the number of control parameters to be tuned for each patient, thereby reducing the clinical time and effort involved in fitting a powered prosthesis for a lower-limb amputee. Using the Discrete Fourier Transformation, a single virtual constraint is derived that exactly characterizes the desired actuated joint motion over the entire gait cycle. Because the virtual constraint is defined as a periodic function of a monotonically increasing phase variable, no switching or resetting is necessary within or across gait cycles. The output function is zeroed using feedback linearization to produce a single, unified controller. The method is illustrated with simulations of a powered knee-ankle prosthesis in an amputee biped model and with examples of systematically generated output functions for different walking speeds. PMID:26913092

  1. 78 FR 71532 - Amendments to Material Control and Accounting Regulations and Proposed Guidance for Fuel Cycle...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ...: I. Background On November 8, 2013 (78 FR 67225; NRC-2009-0096), the NRC published for public comment a proposed rule to amend its regulations for MC&A of SNM. Also on November 8, 2013 (78 FR 67224; NRC... Control and Accounting Regulations and Proposed Guidance for Fuel Cycle Facility Material Control...

  2. Cell-Cycle Control of Bivalent Epigenetic Domains Regulates the Exit from Pluripotency

    PubMed Central

    Singh, Amar M.; Sun, Yuhua; Li, Li; Zhang, Wenjuan; Wu, Tianming; Zhao, Shaying; Qin, Zhaohui; Dalton, Stephen

    2015-01-01

    Summary Here we show that bivalent domains and chromosome architecture for bivalent genes are dynamically regulated during the cell cycle in human pluripotent cells. Central to this is the transient increase in H3K4-trimethylation at developmental genes during G1, thereby creating a “window of opportunity” for cell-fate specification. This mechanism is controlled by CDK2-dependent phosphorylation of the MLL2 (KMT2B) histone methyl-transferase, which facilitates its recruitment to developmental genes in G1. MLL2 binding is required for changes in chromosome architecture around developmental genes and establishes promoter-enhancer looping interactions in a cell-cycle-dependent manner. These cell-cycle-regulated loops are shown to be essential for activation of bivalent genes and pluripotency exit. These findings demonstrate that bivalent domains are established to control the cell-cycle-dependent activation of developmental genes so that differentiation initiates from the G1 phase. PMID:26278042

  3. Cell-Cycle Control of Bivalent Epigenetic Domains Regulates the Exit from Pluripotency.

    PubMed

    Singh, Amar M; Sun, Yuhua; Li, Li; Zhang, Wenjuan; Wu, Tianming; Zhao, Shaying; Qin, Zhaohui; Dalton, Stephen

    2015-09-01

    Here we show that bivalent domains and chromosome architecture for bivalent genes are dynamically regulated during the cell cycle in human pluripotent cells. Central to this is the transient increase in H3K4-trimethylation at developmental genes during G1, thereby creating a "window of opportunity" for cell-fate specification. This mechanism is controlled by CDK2-dependent phosphorylation of the MLL2 (KMT2B) histone methyl-transferase, which facilitates its recruitment to developmental genes in G1. MLL2 binding is required for changes in chromosome architecture around developmental genes and establishes promoter-enhancer looping interactions in a cell-cycle-dependent manner. These cell-cycle-regulated loops are shown to be essential for activation of bivalent genes and pluripotency exit. These findings demonstrate that bivalent domains are established to control the cell-cycle-dependent activation of developmental genes so that differentiation initiates from the G1 phase. PMID:26278042

  4. A new postural balance control system for rehabilitation training based on virtual cycling.

    PubMed

    Song, Chul Gyu; Kim, Jong Yun; Kim, Nam Gyun

    2004-06-01

    A new rehabilitation training system was developed to improve postural balance control by combining virtual reality technology with an unfixed bicycle. Twenty healthy subjects participated in the present study by riding the virtual cycling system under two different conditions: with or without visual feedback. Data were collected on the following parameters: path deviation, cycling velocity, etc. As a result of conducting the repeated training, results showed improvement not only in the ability to control balance and weight shift but also in the overall cycling ability including the degree of path deviation and the cycling speed. It was concluded that the system was effective as a training device and, in addition, the technology might have a wider applicability to the rehabilitation field.

  5. Control system for cheng dual-fluid cycle engine system

    SciTech Connect

    Cheng, D.Y.

    1987-07-21

    A dual-fluid heat engine is described which is operated to produce co-generated process steam having: a chamber; compressor means for introducing a first gaseous working fluid comprising air into the chamber, the compressor means having a predetermined pressure ratio (CPR); means for introducing a second liquid-vapor working fluid comprising water in the form of a vapor within the chamber at a defined water/air working fluid ratio (XMIX); means for heating the water vapor and air in the chamber at a defined specific heat input rate (SHIR); turbine means responsive to the mixture of the first and second working fluids for converting the energy associated with the mixture to mechanical energy, the temperature of the mixture entering the turbine means defining the turbine inlet temperature (TIT) and having a design maximum turbine inlet temperature (TITmax); counterflow heat exchanger means for transferring residual thermal energy from the exhausted mixture of first and second working fluids to the incoming working fluid water to thereby preheat the same to water vapor prior to its introduction within the chamber; means for diverting water vapor from the chamber, if desired, for co-generated process steam; and wherein the improvement comprises: means for operating the engine under partial load conditions such that when substantially no co-generated process steam is required. The engine control path follows a locus of peak efficiency points resulting in declining TIT as the load decreases, and such that XMIX and SHIR are selected so that for a given value of TIT, XMIX is at or near XMIX peak, where XMIX peak occurs when conditions are met simultaneously.

  6. A cell cycle-controlled redox switch regulates the topoisomerase IV activity

    PubMed Central

    Narayanan, Sharath; Janakiraman, Balaganesh; Kumar, Lokesh

    2015-01-01

    Topoisomerase IV (topo IV), an essential factor during chromosome segregation, resolves the catenated chromosomes at the end of each replication cycle. How the decatenating activity of the topo IV is regulated during the early stages of the chromosome cycle despite being in continuous association with the chromosome remains poorly understood. Here we report a novel cell cycle-regulated protein in Caulobacter crescentus, NstA (negative switch for topo IV decatenation activity), that inhibits the decatenation activity of the topo IV during early stages of the cell cycle. We demonstrate that in C. crescentus, NstA acts by binding to the ParC DNA-binding subunit of topo IV. Most importantly, we uncover a dynamic oscillation of the intracellular redox state during the cell cycle, which correlates with and controls NstA activity. Thus, we propose that predetermined dynamic intracellular redox fluctuations may act as a global regulatory switch to control cellular development and cell cycle progression and may help retain pathogens in a suitable cell cycle state when encountering redox stress from the host immune response. PMID:26063575

  7. Chopper-controlled discharge life cycling studies on lead-acid batteries

    NASA Technical Reports Server (NTRS)

    Kraml, J. J.; Ames, E. P.

    1982-01-01

    State-of-the-art 6 volt lead-acid golf car batteries were tested. A daily charge/discharge cycling to failure points under various chopper controlled pulsed dc and continuous current load conditions was undertaken. The cycle life and failure modes were investigated for depth of discharge, average current chopper frequency, and chopper duty cycle. It is shown that battery life is primarily and inversely related to depth of discharge and discharge current. Failure mode is characterized by a gradual capacity loss with consistent evidence of cell element aging.

  8. Input visualization for the Cyclus nuclear fuel cycle simulator: CYClus Input Control

    SciTech Connect

    Flanagan, R.; Schneider, E.

    2013-07-01

    This paper discusses and demonstrates the methods used for the graphical user interface for the Cyclus fuel cycle simulator being developed at the University of Wisconsin-Madison. Cyclus Input Control (CYCIC) is currently being designed with nuclear engineers in mind, but future updates to the program will be made to allow even non-technical users to quickly and efficiently simulate fuel cycles to answer the questions important to them. (authors)

  9. Controls over fungal communities and consequences for nutrient cycling

    NASA Astrophysics Data System (ADS)

    Treseder, K. K.; Majumder, P.; Bent, E.; Borneman, J.; Allison, S. D.; Hanson, C. A.

    2007-12-01

    Soils harbor a high diversity of microbes-- as many as 100 species of fungi within a square meter. If different species target different components of litter, a more diverse community of fungi should lead to faster decomposition rates. We examined the hypotheses that variation in substrate use among fungal groups and variation in nitrogen availability are both important controls over the diversity of fungi in an Alaskan boreal forest. Nitrogen availability was considered because microbes are often N-limited, and because humans are altering N availability via anthropogenic N deposition and global warming. We used nucleotide analogs to link fungal groups with their role in decomposition in field samples. Leaf litter collected from the forest floor was supplemented with one of four N-containing compounds. Bromodeoxyuridine (BrdU, a thymidine analog) was also added. After 48 hours incubation, DNA was extracted. Most growing fungi should have assimilated the BrdU into new DNA. Their genetic identity was determined using oligonucleotide fingerprinting of rRNA genes (OFRG). OFRG is an rRNA gene profiling method that sorts genes into taxonomic groups with a high degree of resolution, and has a large capacity for sample processing. Fungal groups that proliferated following the addition of a given compound probably metabolized that compound. We found that fungal taxa varied in their responses to different substrates, indicating that they differed in substrate use. Specifically, community composition of fungi was significantly different among substrate treatments (P < 0.001). In addition, of the 15 dominant taxa, seven displayed significant preferences for one substrate over another. For instance, taxa within the Helotiales preferred glutamate (P = 0.001); Sporidiales, tannin-protein complexes (P = 0.014); Saccharomycetales, arginine (P = 0.042); and Polyporales, arginine and lignocellulose (P = 0.040). In a complementary experiment, we used BrdU labeling to characterize

  10. Advanced Shock Position Control for Mode Transition in a Turbine Based Combined Cycle Engine Inlet Model

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey T.; Stueber, Thomas J.

    2013-01-01

    A dual flow-path inlet system is being tested to evaluate methodologies for a Turbine Based Combined Cycle (TBCC) propulsion system to perform a controlled inlet mode transition. Prior to experimental testing, simulation models are used to test, debug, and validate potential control algorithms. One simulation package being used for testing is the High Mach Transient Engine Cycle Code simulation, known as HiTECC. This paper discusses the closed loop control system, which utilizes a shock location sensor to improve inlet performance and operability. Even though the shock location feedback has a coarse resolution, the feedback allows for a reduction in steady state error and, in some cases, better performance than with previous proposed pressure ratio based methods. This paper demonstrates the design and benefit with the implementation of a proportional-integral controller, an H-Infinity based controller, and a disturbance observer based controller.

  11. Model predictive control system and method for integrated gasification combined cycle power generation

    SciTech Connect

    Kumar, Aditya; Shi, Ruijie; Kumar, Rajeeva; Dokucu, Mustafa

    2013-04-09

    Control system and method for controlling an integrated gasification combined cycle (IGCC) plant are provided. The system may include a controller coupled to a dynamic model of the plant to process a prediction of plant performance and determine a control strategy for the IGCC plant over a time horizon subject to plant constraints. The control strategy may include control functionality to meet a tracking objective and control functionality to meet an optimization objective. The control strategy may be configured to prioritize the tracking objective over the optimization objective based on a coordinate transformation, such as an orthogonal or quasi-orthogonal projection. A plurality of plant control knobs may be set in accordance with the control strategy to generate a sequence of coordinated multivariable control inputs to meet the tracking objective and the optimization objective subject to the prioritization resulting from the coordinate transformation.

  12. Cycling exercise with functional electrical stimulation improves postural control in stroke patients.

    PubMed

    Lo, Hsin-Chang; Hsu, Yung-Chun; Hsueh, Ya-Hsin; Yeh, Chun-Yu

    2012-03-01

    The aim of this study is to determine whether short term functional electrical stimulation (FES)-assisted cycling training can affect the postural control of stroke patients, and whether the application of FES can enhance the effect of cycling training. 20 stroke patients were randomly assigned to the FES-cycling group (FES-CG) or the cycling group (CG). Measurements were completed before and immediately after each 20 min training sessions. The measurements included a balance test (to quantify the postural control ability), a Hoffmann's reflex/motor response ratio (H/M ratio) test and a pendulum test (to quantify the muscle tone). In the balance test, some parameters in all directions exhibited significant intervention effects between the FES-CG group and the CG group. The H/M ratios (p=.014; .005, FES-CG and CG respectively) and relaxation index (p=.005; .047, FES-CG and CG respectively) revealed significant difference between FES-CG and CG group. The change ratios of directional control in the forward direction and H/M ratio revealed significant difference (p=.022; .015) between FES-CG and CG among subjects with higher muscle tone. The stroke subjects' postural control was improved while their muscle tone was reduced after the 20 min cycling training program both with and without FES. We conclude that cycling training, with or without FES may reduce spasticity in stroke patients. The application of FES in cycling exercise was shown to be more effective in stroke patients with higher muscle tone.

  13. Cycling exercise with functional electrical stimulation improves postural control in stroke patients.

    PubMed

    Lo, Hsin-Chang; Hsu, Yung-Chun; Hsueh, Ya-Hsin; Yeh, Chun-Yu

    2012-03-01

    The aim of this study is to determine whether short term functional electrical stimulation (FES)-assisted cycling training can affect the postural control of stroke patients, and whether the application of FES can enhance the effect of cycling training. 20 stroke patients were randomly assigned to the FES-cycling group (FES-CG) or the cycling group (CG). Measurements were completed before and immediately after each 20 min training sessions. The measurements included a balance test (to quantify the postural control ability), a Hoffmann's reflex/motor response ratio (H/M ratio) test and a pendulum test (to quantify the muscle tone). In the balance test, some parameters in all directions exhibited significant intervention effects between the FES-CG group and the CG group. The H/M ratios (p=.014; .005, FES-CG and CG respectively) and relaxation index (p=.005; .047, FES-CG and CG respectively) revealed significant difference between FES-CG and CG group. The change ratios of directional control in the forward direction and H/M ratio revealed significant difference (p=.022; .015) between FES-CG and CG among subjects with higher muscle tone. The stroke subjects' postural control was improved while their muscle tone was reduced after the 20 min cycling training program both with and without FES. We conclude that cycling training, with or without FES may reduce spasticity in stroke patients. The application of FES in cycling exercise was shown to be more effective in stroke patients with higher muscle tone. PMID:22153770

  14. A microbial avenue to cell cycle control in the plant superkingdom.

    PubMed

    Tulin, Frej; Cross, Frederick R

    2014-10-01

    Research in yeast and animals has resulted in a well-supported consensus model for eukaryotic cell cycle control. The fit of this model to early diverging eukaryotes, such as the plant kingdom, remains unclear. Using the green alga Chlamydomonas reinhardtii, we developed an efficient pipeline, incorporating robotics, semiautomated image analysis, and deep sequencing, to molecularly identify >50 genes, mostly conserved in higher plants, specifically required for cell division but not cell growth. Mutated genes include the cyclin-dependent kinases CDKA (resembling yeast and animal Cdk1) and the plant-specific CDKB. The Chlamydomonas cell cycle consists of a long G1 during which cells can grow >10-fold, followed by multiple rapid cycles of DNA replication and segregation. CDKA and CDKB execute nonoverlapping functions: CDKA promotes transition between G1 and entry into the division cycle, while CDKB is essential specifically for spindle formation and nuclear division, but not for DNA replication, once CDKA-dependent initiation has occurred. The anaphase-promoting complex is required for similar steps in the Chlamydomonas cell cycle as in Opisthokonts; however, the spindle assembly checkpoint, which targets the APC in Opisthokonts, appears severely attenuated in Chlamydomonas, based on analysis of mutants affecting microtubule function. This approach allows unbiased integration of the consensus cell cycle control model with innovations specific to the plant lineage.

  15. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  16. Identification and cell cycle control of a novel pilus system in Caulobacter crescentus

    PubMed Central

    Skerker, Jeffrey M.; Shapiro, Lucy

    2000-01-01

    Pilus assembly in Caulobacter crescentus occurs during a short period of the cell cycle and pili are only present at the flagellar pole of the swarmer cell. Here we report a novel assay to visualize pili by light microscopy that led to the purification of Caulobacter pili and the isolation of a cluster of seven genes, including the major pilin subunit gene pilA. This gene cluster encodes a novel group of pilus assembly proteins. We have shown that the pilA promoter is activated late in the cell cycle and that transcription of the pilin subunit plays an important role in the timing of pilus assembly. pilA transcription is regulated by the global two-component response regulator CtrA, which is essential for the expression of multiple cell cycle events, providing a direct link between assembly of the pilus organelle and bacterial cell cycle control. PMID:10880436

  17. Concise Review: Control of Cell Fate Through Cell Cycle and Pluripotency Networks.

    PubMed

    Boward, Ben; Wu, Tianming; Dalton, Stephen

    2016-06-01

    Pluripotent stem cells (PSCs) proliferate rapidly with a characteristic cell cycle structure consisting of short G1- and G2-gap phases. This applies broadly to PSCs of peri-implantation stage embryos, cultures of embryonic stem cells, induced pluripotent stem cells, and embryonal carcinoma cells. During the early stages of PSC differentiation however, cell division times increase as a consequence of cell cycle remodeling. Most notably, this is indicated by elongation of the G1-phase. Observations linking changes in the cell cycle with exit from pluripotency have raised questions about the role of cell cycle control in maintenance of the pluripotent state. Until recently however, this has been a difficult question to address because of limitations associated with experimental tools. Recent studies now show that pluripotency and cell cycle regulatory networks are intertwined and that cell cycle control mechanisms are an integral, mechanistic part of the PSC state. Studies in embryonal carcinoma, some 30 years ago, first suggested that pluripotent cells initiate differentiation when in the G1-phase. More recently, a molecular "priming" mechanism has been proposed to explain these observations in human embryonic stem cells. Complexity in this area has been increased by the realization that pluripotent cells exist in multiple developmental states and that in addition to each having their own characteristic gene expression and epigenetic signatures, they potentially have alternate modes of cell cycle regulation. This review will summarize current knowledge in these areas and will highlight important aspects of interconnections between the cell cycle, self-renewal, pluripotency, and cell fate decisions. Stem Cells 2016;34:1427-1436.

  18. DNA replication and damage checkpoints and meiotic cell cycle controls in the fission and budding yeasts.

    PubMed Central

    Murakami, H; Nurse, P

    2000-01-01

    The cell cycle checkpoint mechanisms ensure the order of cell cycle events to preserve genomic integrity. Among these, the DNA-replication and DNA-damage checkpoints prevent chromosome segregation when DNA replication is inhibited or DNA is damaged. Recent studies have identified an outline of the regulatory networks for both of these controls, which apparently operate in all eukaryotes. In addition, it appears that these checkpoints have two arrest points, one is just before entry into mitosis and the other is prior to chromosome separation. The former point requires the central cell-cycle regulator Cdc2 kinase, whereas the latter involves several key regulators and substrates of the ubiquitin ligase called the anaphase promoting complex. Linkages between these cell-cycle regulators and several key checkpoint proteins are beginning to emerge. Recent findings on post-translational modifications and protein-protein interactions of the checkpoint proteins provide new insights into the checkpoint responses, although the functional significance of these biochemical properties often remains unclear. We have reviewed the molecular mechanisms acting at the DNA-replication and DNA-damage checkpoints in the fission yeast Schizosaccharomyces pombe, and the modifications of these controls during the meiotic cell cycle. We have made comparisons with the controls in fission yeast and other organisms, mainly the distantly related budding yeast. PMID:10861204

  19. Topology and Control of the Cell-Cycle-Regulated Transcriptional Circuitry

    PubMed Central

    Haase, Steven B.; Wittenberg, Curt

    2014-01-01

    Nearly 20% of the budding yeast genome is transcribed periodically during the cell division cycle. The precise temporal execution of this large transcriptional program is controlled by a large interacting network of transcriptional regulators, kinases, and ubiquitin ligases. Historically, this network has been viewed as a collection of four coregulated gene clusters that are associated with each phase of the cell cycle. Although the broad outlines of these gene clusters were described nearly 20 years ago, new technologies have enabled major advances in our understanding of the genes comprising those clusters, their regulation, and the complex regulatory interplay between clusters. More recently, advances are being made in understanding the roles of chromatin in the control of the transcriptional program. We are also beginning to discover important regulatory interactions between the cell-cycle transcriptional program and other cell-cycle regulatory mechanisms such as checkpoints and metabolic networks. Here we review recent advances and contemporary models of the transcriptional network and consider these models in the context of eukaryotic cell-cycle controls. PMID:24395825

  20. p53 as Batman: using a movie plot to understand control of the cell cycle.

    PubMed

    Gadi, Nikhita; Foley, Sage E; Nowey, Mark; Plopper, George E

    2013-04-16

    This Teaching Resource provides and describes a two-part classroom exercise to help students understand control of the cell cycle, with a focus on the transcription factor p53, the E3 ubiquitin ligase Mdm2, the Mdm2 inhibitor ARF, the kinases ATM and ATR, the kinase Chk2, and the cell cycle inhibitor p21(Cip1). Students use characters and scenes from the movie The Dark Knight to represent elements of the cell cycle control machinery, then they apply these characters and scenes to translate a primary research article on p53 function into a new movie scene in the "Batman universe." This exercise is appropriate for college-level courses in cell biology and cancer biology and requires students to have a background in introductory cell biology. Explicit learning outcomes and associated assessment methods are provided, as well as slides, student assignments, the primary research article, and an instructor's guide for the exercise.

  1. Life cycle and control of the cyst nematode Heterodera goldeni on rice in Egypt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The life cycle and methods for control of the cyst nematode Heterodera goldeni on rice (Oryza sativa) were examined in the greenhouse. Three tests were conducted to study the effects of soil treatments with some plant materials, stems of oyster mushroom (Pleurotus ostreatus), the biocontrol agent Ba...

  2. How neurons make us jump: the neural control of stretch-shortening cycle movements.

    PubMed

    Taube, Wolfgang; Leukel, Christian; Gollhofer, Albert

    2012-04-01

    How can the human central nervous system (CNS) control complex jumping movements task- and context-specifically? This review highlights the complex interaction of multiple hierarchical levels of the CNS, which work together to enable stretch-shortening cycle contractions composed of activity resulting from feedforward (preprogrammed) and feedback (reflex) loops.

  3. DNA DAMAGE REPAIR AND CELL CYCLE CONTROL: A NATURAL BIO-DEFENSE MECHANISM

    EPA Science Inventory

    DNA DAMAGE REPAIR AND CELL CYCLE CONTROL: A natural bio-defense mechanism
    Anuradha Mudipalli.

    Maintenance of genetic information, including the correct sequence of nucleotides in DNA, is essential for replication, gene expression, and protein synthesis. DNA lesions onto...

  4. Optimum Duty Cycle of Unsteady Plasma Aerodynamic Actuation for NACA0015 Airfoil Stall Separation Control

    NASA Astrophysics Data System (ADS)

    Sun, Min; Yang, Bo; Peng, Tianxiang; Lei, Mingkai

    2016-06-01

    Unsteady dielectric barrier discharge (DBD) plasma aerodynamic actuation technology is employed to suppress airfoil stall separation and the technical parameters are explored with wind tunnel experiments on an NACA0015 airfoil by measuring the surface pressure distribution of the airfoil. The performance of the DBD aerodynamic actuation for airfoil stall separation suppression is evaluated under DBD voltages from 2000 V to 4000 V and the duty cycles varied in the range of 0.1 to 1.0. It is found that higher lift coefficients and lower threshold voltages are achieved under the unsteady DBD aerodynamic actuation with the duty cycles less than 0.5 as compared to that of the steady plasma actuation at the same free-stream speeds and attack angles, indicating a better flow control performance. By comparing the lift coefficients and the threshold voltages, an optimum duty cycle is determined as 0.25 by which the maximum lift coefficient and the minimum threshold voltage are obtained at the same free-stream speed and attack angle. The non-uniform DBD discharge with stronger discharge in the positive half cycle due to electrons deposition on the dielectric slabs and the suppression of opposite momentum transfer due to the intermittent discharge with cutoff of the negative half cycle are responsible for the observed optimum duty cycle. supported by National Natural Science Foundation of China (No. 21276036), Liaoning Provincial Natural Science Foundation of China (No. 2015020123) and the Fundamental Research Funds for the Central Universities of China (No. 3132015154)

  5. Acute effect of cycling intervention on carotid arterial hemodynamics: basketball athletes versus sedentary controls

    PubMed Central

    2015-01-01

    Objective To compare the acute effects of a cycling intervention on carotid arterial hemodynamics between basketball athletes and sedentary controls. Methods Ten young long-term trained male basketball athletes (BA) and nine age-matched male sedentary controls (SC) successively underwent four bouts of exercise on a bicycle ergometer at the same workload. Hemodynamic variables at right common carotid artery were determined at rest and immediately following each bout of exercise. An ANCOVA was used to compare differences between the BA and SC groups at rest and immediately following the cycling intervention. The repeated ANOVA was used to assess differences between baseline and each bout of exercise within the BA or SC group. Results In both groups, carotid hemodynamic variables showed significant differences at rest and immediately after the cycling intervention. At rest, carotid arterial stiffness was significantly decreased and carotid arterial diameter was significantly increased in the BA group as compared to the SC group. Immediately following the cycling intervention, carotid arterial stiffness showed no obvious changes in the BA group but significantly increased in the SC group. It is worth noting that while arterial stiffness was lower in the BA group than in the SC group, the oscillatory shear index (OSI) was significantly higher in the BA group than in the SC group both at rest and immediately following the cycling intervention. Conclusion Long-term basketball exercise had a significant impact on common carotid arterial hemodynamic variables not only at rest but also after a cycling intervention. The role of OSI in the remodeling of arterial structure and function in the BA group at rest and after cycling requires clarification. PMID:25602805

  6. E2F Transcription Factors Control the Roller Coaster Ride of Cell Cycle Gene Expression.

    PubMed

    Thurlings, Ingrid; de Bruin, Alain

    2016-01-01

    Initially, the E2F transcription factor was discovered as a factor able to bind the adenovirus E2 promoter and activate viral genes. Afterwards it was shown that E2F also binds to promoters of nonviral genes such as C-MYC and DHFR, which were already known at that time to be important for cell growth and DNA metabolism, respectively. These findings provided the first clues that the E2F transcription factor might be an important regulator of the cell cycle. Since this initial discovery in 1987, several additional E2F family members have been identified, and more than 100 targets genes have been shown to be directly regulated by E2Fs, the majority of these are important for controlling the cell cycle. The progression of a cell through the cell cycle is accompanied with the increased expression of a specific set of genes during one phase of the cell cycle and the decrease of the same set of genes during a later phase of the cell cycle. This roller coaster ride, or oscillation, of gene expression is essential for the proper progression through the cell cycle to allow accurate DNA replication and cell division. The E2F transcription factors have been shown to be critical for the temporal expression of the oscillating cell cycle genes. This review will focus on how the oscillation of E2Fs and their targets is regulated by transcriptional, post-transcriptional and post-translational mechanism in mammals, yeast, flies, and worms. Furthermore, we will discuss the functional impact of E2Fs on the cell cycle progression and outline the consequences when E2F expression is disturbed. PMID:26254918

  7. Robustness and adaptation reveal plausible cell cycle controlling subnetwork in Saccharomyces cerevisiae.

    PubMed

    Huang, Jiun-Yan; Huang, Chi-Wei; Kao, Kuo-Ching; Lai, Pik-Yin

    2013-04-10

    Biological systems are often organized spatially and temporally by multi-scale functional subsystems (modules). A specific subcellular process often corresponds to a subsystem composed of some of these interconnected modules. Accurate identification of system-level modularity organization from the large scale networks can provide valuable information on subsystem models of subcellular processes or physiological phenomena. Computational identification of functional modules from the large scale network is the key approach to solve the complexity of modularity in the past decade, but the overlapping and multi-scale nature of modules often renders unsatisfactory results in these methods. Most current methods for modularity detection are optimization-based and suffered from the drawback of size resolution limit. It is difficult to trace the origin of the unsatisfactory results, which may be due to poor data, inappropriate objective function selection or simply resulted from natural evolution, and hence no system-level accurate modular models for subcellular processes can be offered. Motivated by the idea of evolution with robustness and adaption as guiding principles, we propose a novel approach that can identify significant multi-scale overlapping modules that are sufficiently accurate at the system and subsystem levels, giving biological insights for subcellular processes. The success of our evolution strategy method is demonstrated by applying to the yeast protein-protein interaction network. Functional subsystems of important physiological phenomena can be revealed. In particular, the cell cycle controlling network is selected for detailed discussion. The cell cycle subcellular processes in yeast can be successfully dissected into functional modules of cell cycle control, cell size check point, spindle assembly checkpoint, and DNA damage check point in G2/M and S phases. The interconnections between check points and cell cycle control modules provide clues on the

  8. Aggregate-Scale Variation in Iron Biogeochemistry Controls Element Cycling from Nitrogen to Uranium

    NASA Astrophysics Data System (ADS)

    Fendorf, S. E.; Ying, S.; Jones, L. C.; Jones, M. E.

    2014-12-01

    Iron exerts a major control on element cycling in soils by serving as a prominent sorbent (principally when present as an oxide phase) and as an electron acceptor (in the ferric-form) or donor (ferrous-form) in both chemical and microbially-mediated reactions. Within the aggregated structure of soils, steep chemical gradients arise from the supply of oxygen and nutrients along macropores that are rapidly consumed (relative to supply) within the micropore domains of aggregate interiors. As a consequence, iron undergoes a dynamic biogeochemical cycle whereby ferric (hydr)oxides form within aggregate exteriors while ferrous-iron generation dominates within interior regions. Further, inter-aggregate cycling of iron can transpire through the supply of electron donors and acceptors, linked with diffusive controlled response to gradients. Coupling to iron transformation are the varying retention of adsorptives such as lead and phosphorus and the redox alterations of elements from nitrogen to uranium. Nitrate, for example, diffusing into aggregate interiors encounters ferrous-iron fronts where the ensuring oxidation of Fe(II)-coupled to nitrate reduction transpires. The outcome of aggregate-scale iron transformations, described within this presentation, is fundamental controls on the cycling of redox active elements from nutrients such as carbon and nitrogen to contaminants such arsenic and uranium.

  9. Tunable Signal Processing through a Kinase Control Cycle: the IKK Signaling Node

    PubMed Central

    Behar, Marcelo; Hoffmann, Alexander

    2013-01-01

    The transcription factor NFκB, a key component of the immune system, shows intricate stimulus-specific temporal dynamics. Those dynamics are thought to play a role in controlling the physiological response to cytokines and pathogens. Biochemical evidence suggests that the NFκB inducing kinase, IKK, a signaling hub onto which many signaling pathways converge, is regulated via a regulatory cycle comprising a poised, an active, and an inactive state. We hypothesize that it operates as a modulator of signal dynamics, actively reshaping the signals generated at the receptor proximal level. Here we show that a regulatory cycle can function in at least three dynamical regimes, tunable by regulating a single kinetic parameter. In particular, the simplest three-state regulatory cycle can generate signals with two well-defined phases, each with distinct coding capabilities in terms of the information they can carry about the stimulus. We also demonstrate that such a kinase cycle can function as a signal categorizer classifying diverse incoming signals into outputs with a limited set of temporal activity profiles. Finally, we discuss the extension of the results to other regulatory motifs that could be understood in terms of the regimes of the three-state cycle. PMID:23823243

  10. SAMHD1 controls cell cycle status, apoptosis and HIV-1 infection in monocytic THP-1 cells.

    PubMed

    Bonifati, Serena; Daly, Michele B; St Gelais, Corine; Kim, Sun Hee; Hollenbaugh, Joseph A; Shepard, Caitlin; Kennedy, Edward M; Kim, Dong-Hyun; Schinazi, Raymond F; Kim, Baek; Wu, Li

    2016-08-01

    SAMHD1 limits HIV-1 infection in non-dividing myeloid cells by decreasing intracellular dNTP pools. HIV-1 restriction by SAMHD1 in these cells likely prevents activation of antiviral immune responses and modulates viral pathogenesis, thus highlighting a critical role of SAMHD1 in HIV-1 physiopathology. Here, we explored the function of SAMHD1 in regulating cell proliferation, cell cycle progression and apoptosis in monocytic THP-1 cells. Using the CRISPR/Cas9 technology, we generated THP-1 cells with stable SAMHD1 knockout. We found that silencing of SAMHD1 in cycling cells stimulates cell proliferation, redistributes cell cycle population in the G1/G0 phase and reduces apoptosis. These alterations correlated with increased dNTP levels and more efficient HIV-1 infection in dividing SAMHD1 knockout cells relative to control. Our results suggest that SAMHD1, through its dNTPase activity, affects cell proliferation, cell cycle distribution and apoptosis, and emphasize a key role of SAMHD1 in the interplay between cell cycle regulation and HIV-1 infection. PMID:27183329

  11. Controls on aquatic carbon cycling in a carbonate dominated groundwater catchment using dissolved oxygen dynamics

    NASA Astrophysics Data System (ADS)

    Butler, A. P.; Parker, S. J.

    2015-12-01

    Carbon cycling in aquatic systems is increasingly seen as playing an important role in global carbon budgets and hence on potential impacts and controls on global warming. However, determining the partitioning within and transfer between different carbon stores is a major challenge, particularly where there are multiple sources and controls on carbon utilisation. Dissolved oxygen, DO, provides a proxy for investigating the dynamics of carbon utilisation in aquatic systems. High temporal resolution monitoring of DO at multiple site on the Hampshire Avon, a chalk dominated permeable catchment in southern England, UK, has been investigated using a dynamic DO model in order to investigate the biochemical cycling of carbon. Gross primary production, governed by photosynthetically active radiation, is determined through inverse modelling. Model simplification though parameter reduction is achieved through investigating controls on aeration (the transfer of oxygen across the atmosphere-river interface) and respiration. Seasonal changes in biomass affect long term oxygen dynamics, which are compounded by episodic hydrological events that control the partitioning of surface water and groundwater in the stream channel and consequently the sources of carbon and DO in the river channel. Using variations in surface geology across the catchment the impacts of varying baseflow characteristics on carbon cycling within the catchment is demonstrated.

  12. Avulsion cycles and their stratigraphic signature on an experimental backwater-controlled delta

    NASA Astrophysics Data System (ADS)

    Ganti, Vamsi; Chadwick, Austin J.; Hassenruck-Gudipati, Hima J.; Lamb, Michael P.

    2016-09-01

    River deltas grow in large part through repeated cycles of lobe construction and channel avulsion. Understanding avulsion cycles is important for coastal restoration and ecology, land management, and flood hazard mitigation. Emerging theories suggest that river avulsions on lowland deltas are controlled by backwater hydrodynamics; however, our knowledge of backwater-controlled avulsion cycles is limited. Here we present results from an experimental delta that evolved under persistent backwater hydrodynamics achieved through variable flood discharges, shallow bed slopes, and subcritical flows. The experimental avulsion cycles consisted of an initial phase of avulsion setup, an avulsion trigger, selection of a new flow path, and abandonment of the parent channel. Avulsions were triggered during the largest floods (78% of avulsions) after the channel was filled by a fraction (0.3 ± 0.13) of its characteristic flow depth at the avulsion site, which occurred in the upstream part of the backwater zone. The new flow path following avulsion was consistently one of the shortest paths to the shoreline, and channel abandonment occurred through temporal decline in water flow and sediment delivery to the parent channel. Experimental synthetic stratigraphy indicates that bed thicknesses were maximum at the avulsion sites, consistent with our morphologic measurements of avulsion setup and the idea that there is a record of avulsion locations and thresholds in sedimentary rocks. Finally, we discuss the implications of our findings within the context of sustainable management of deltas, their stratigraphic record, and predicting avulsions on deltas.

  13. Topological control of the Caulobacter cell cycle circuitry by a polarized single-domain PAS protein

    PubMed Central

    Sanselicio, Stefano; Bergé, Matthieu; Théraulaz, Laurence; Radhakrishnan, Sunish Kumar; Viollier, Patrick H.

    2015-01-01

    Despite the myriad of different sensory domains encoded in bacteria, only a few types are known to control the cell cycle. Here we use a forward genetic screen for Caulobacter crescentus motility mutants to identify a conserved single-domain PAS (Per-Arnt-Sim) protein (MopJ) with pleiotropic regulatory functions. MopJ promotes re-accumulation of the master cell cycle regulator CtrA after its proteolytic destruction is triggered by the DivJ kinase at the G1-S transition. MopJ and CtrA syntheses are coordinately induced in S-phase, followed by the sequestration of MopJ to cell poles in Caulobacter. Polarization requires Caulobacter DivJ and the PopZ polar organizer. MopJ interacts with DivJ and influences the localization and activity of downstream cell cycle effectors. Because MopJ abundance is upregulated in stationary phase and by the alarmone (p)ppGpp, conserved systemic signals acting on the cell cycle and growth phase control are genetically integrated through this conserved single PAS-domain protein. PMID:25952018

  14. The effect of endometrial injury on first cycle IVF/ICSI outcome: A randomized controlled trial

    PubMed Central

    Mahran, Ahmad; Ibrahim, Mahmoud; Bahaa, Haitham

    2016-01-01

    Background: Implantation remains a limiting step in IVF/ICSI. Endometrial injury isa promising procedure aiming at improving the implantation and pregnancy rates after IVF/ICSI. Objective: The aim of this study was to evaluate the effect of endometrial injury induced in precedingcycle on IVF/ICSI outcome. Materials and Methods: Four hundred patients undergoing their first IVF/ICSI cycle in two IVF units in Minia, Egypt were randomly selected to undergo either endometrial injury in luteal phase of preceding cycle (intervention group) or no treatment (control group). Primary outcome wasthe implantation and live birth ratesWhile the secondary outcome was clinical pregnancy, miscarriage, multiple pregnancy rates, pain and bleeding during and after procedure. Results: Implantation and live birth rates were significantly higher in intervention compared with control group (22.4% vs. 18.7%, p=0.02 and 67% vs. 28%, p=0.03), respectively. There was also a significant reduction in miscarriage rate in intervention group (4.8% vs. 19.7%, respectively, p<0.001). Conclusion: Endometrial injury in preceding cycle improves the implantation rate and live birth rate and reduces the miscarriage rate per clinical pregnancy in patients undergoing their first IVF/ICSI cycle. PMID:27294218

  15. Intelligent approach for parallel HEV control strategy based on driving cycles

    NASA Astrophysics Data System (ADS)

    Montazeri-Gh, M.; Asadi, M.

    2011-02-01

    This article describes a methodological approach for the intelligent control of parallel hybrid electric vehicle (HEV) by the inclusion of the concept of driving cycles. In this approach, a fuzzy logic controller is designed to manage the internal combustion engine to work in the vicinity of its optimal condition instantaneously. In addition, based on the definition of microtrip, several driving patterns are classified that represent the congested to highway traffic conditions. The driving cycle and traffic conditions are then incorporated in an optimisation process to tune the fuzzy membership function parameters. In this study, the optimisation process is formulated to minimise the HEV fuel consumption (FC) and emissions as well as the satisfaction of the driving performance constraints. Finally, optimisation results are provided for three different driving cycles including ECE-EUDC, FTP and TEH-CAR. TEH-CAR is a driving cycle that is developed based on the experimental data collected from the real traffic condition in the city of Tehran. The results from the computer simulation show the effectiveness of the approach and reduction in FC and emissions while ensuring that the vehicle performance is not sacrificed.

  16. Mycorrhizal Controls on Nitrogen Uptake Drive Carbon Cycling at the Global Scale

    NASA Astrophysics Data System (ADS)

    Shi, M.; Fisher, J. B.; Brzostek, E. R.; Phillips, R.

    2015-12-01

    Nearly all plants form symbiotic relationships with one of two types of mycorrhizal fungi—arbuscular mycorrhizae (AM) and ectomycorrhizal (ECM) fungi, which are essential to global biogeochemical cycling of nutrient elements. In soils with higher rates of nitrogen and phosphorus mineralization from organic matter, AM-associated plants can be better adapted than ECM-associated plants. Importantly, the photosynthate costs of nutrient uptake for AM-associated plants are usually lower than that for ECM-associated plants. Thus, the global carbon cycle is closely coupled with mycorrhizal controls on N uptake. To investigate the potential climate dependence of terrestrial environments from AM- and ECM-associated plants, this study uses the Community Atmosphere Model (CAM) with a plant productivity-optimized N acquisition model—the Fixation and Uptake of Nitrogen (FUN) model—integrated into its land model—the Community Land Model (CLM). This latest version of CLM coupled with FUN allows for the assessment of mycorrhizal controls on global biogeochemical cycling. Here, we show how the historical evolution of AM- and ECM-associations altered regional and global biogeochemical cycling and climate, and future projections over the next century.

  17. Reference H Cycle 3 Stability, Control, and Flying Qualities Batch Assessments

    NASA Technical Reports Server (NTRS)

    Henderson, Dennis K.

    1999-01-01

    This work is an update of the assessment completed in February of 1996, when a preliminary assessment report was issued for the Cycle 2B simulation model. The primary purpose of the final assessment was to re-evaluate each assessment against the flight control system (FCS) requirements document using the updated model. Only a limited number of final assessments were completed due to the close proximity of the release of the Langley model and the assessment deliverable date. The assessment used the nonlinear Cycle 3 simulation model because it combines nonlinear aeroelastic (quasi-static) aerodynamic with hinge moment and rate limited control surface deflections. Both Configuration Aerodynamics (Task 32) and Flight Controls (Task 36) were funded in 1996 to conduct the final stability and control assessments of the unaugmented Reference H configuration in FY96. Because the two tasks had similar output requirements, the work was divided such that Flight Controls would be responsible for the implementation and checkout of the simulation model and Configuration Aerodynamics for writing Madab "script' files, conducting the batch assessments and writing the assessment report. Additionally, Flight Controls was to investigate control surface allocations schemes different from the baseline Reference H in an effort to fulfill flying qualities criteria.

  18. Shock Position Control for Mode Transition in a Turbine Based Combined Cycle Engine Inlet Model

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey T.; Stueber, Thomas J.

    2013-01-01

    A dual flow-path inlet for a turbine based combined cycle (TBCC) propulsion system is to be tested in order to evaluate methodologies for performing a controlled inlet mode transition. Prior to experimental testing, simulation models are used to test, debug, and validate potential control algorithms which are designed to maintain shock position during inlet disturbances. One simulation package being used for testing is the High Mach Transient Engine Cycle Code simulation, known as HiTECC. This paper discusses the development of a mode transition schedule for the HiTECC simulation that is analogous to the development of inlet performance maps. Inlet performance maps, derived through experimental means, describe the performance and operability of the inlet as the splitter closes, switching power production from the turbine engine to the Dual Mode Scram Jet. With knowledge of the operability and performance tradeoffs, a closed loop system can be designed to optimize the performance of the inlet. This paper demonstrates the design of the closed loop control system and benefit with the implementation of a Proportional-Integral controller, an H-Infinity based controller, and a disturbance observer based controller; all of which avoid inlet unstart during a mode transition with a simulated disturbance that would lead to inlet unstart without closed loop control.

  19. Proper orthogonal decomposition analysis for cycle-to-cycle variations of engine flow. Effect of a control device in an inlet pipe

    NASA Astrophysics Data System (ADS)

    Vu, Trung-Thanh; Guibert, Philippe

    2012-06-01

    This paper aims to investigate cycle-to-cycle variations of non-reacting flow inside a motored single-cylinder transparent engine in order to judge the insertion amplitude of a control device able to displace linearly inside the inlet pipe. Three positions corresponding to three insertion amplitudes are implemented to modify the main aerodynamic properties from one cycle to the next. Numerous particle image velocimetry (PIV) two-dimensional velocity fields following cycle database are post-treated to discriminate specific contributions of the fluctuating flow. We performed a multiple snapshot proper orthogonal decomposition (POD) in the tumble plane of a pent roof SI engine. The analytical process consists of a triple decomposition for each instantaneous velocity field into three distinctive parts named mean part, coherent part and turbulent part. The 3rd- and 4th-centered statistical moments of the proper orthogonal decomposition (POD)-filtered velocity field as well as the probability density function of the PIV realizations proved that the POD extracts different behaviors of the flow. Especially, the cyclic variability is assumed to be contained essentially in the coherent part. Thus, the cycle-to-cycle variations of the engine flows might be provided from the corresponding POD temporal coefficients. It has been shown that the in-cylinder aerodynamic dispersions can be adapted and monitored by controlling the insertion depth of the control instrument inside the inlet pipe.

  20. Refrigerator with variable capacity compressor and cycle priming action through capacity control and associated methods

    DOEpatents

    Gomes, Alberto Regio; Litch, Andrew D.; Wu, Guolian

    2016-03-15

    A refrigerator appliance (and associated method) that includes a condenser, evaporator and a multi-capacity compressor. The appliance also includes a pressure reducing device arranged within an evaporator-condenser refrigerant circuit, and a valve system for directing or restricting refrigerant flow through the device. The appliance further includes a controller for operating the compressor upon the initiation of a compressor ON-cycle at a priming capacity above a nominal capacity for a predetermined or calculated duration.

  1. The role of perceived control over anxiety in prospective symptom reports across the menstrual cycle.

    PubMed

    Mahon, Jennifer N; Rohan, Kelly J; Nillni, Yael I; Zvolensky, Michael J

    2015-04-01

    The present investigation tested the role of psychological vulnerabilities to anxiety in reported menstrual symptom severity. Specifically, the current study tested the incremental validity of perceived control over anxiety-related events in predicting menstrual symptom severity, controlling for the effect of anxiety sensitivity, a documented contributor to menstrual distress. It was expected that women with lower perceived control over anxiety-related events would report greater menstrual symptom severity, particularly in the premenstrual phase. A sample of 49 normally menstruating women, aged 18-47 years, each prospectively tracked their menstrual symptoms for one cycle and completed the Anxiety Control Questionnaire (Rapee, Craske, Brown, & Barlow Behav Ther 27:279-293. doi: 10.1016/S0005-7894(96)80018-9 , 1996) in their follicular and premenstrual phases. A mixed model analysis revealed perceived control over anxiety-related events was a more prominent predictor of menstrual symptom severity than anxiety sensitivity, regardless of the current cycle phase. This finding provides preliminary evidence that perceived control over anxiety-related events is associated with the perceived intensity of menstrual symptoms. This finding highlights the role of psychological vulnerabilities in menstrual distress. Future research should examine whether psychological interventions that target cognitive vulnerabilities to anxiety may help reduce severe menstrual distress.

  2. Endosymbiosis in trypanosomatid protozoa: the bacterium division is controlled during the host cell cycle.

    PubMed

    Catta-Preta, Carolina M C; Brum, Felipe L; da Silva, Camila C; Zuma, Aline A; Elias, Maria C; de Souza, Wanderley; Schenkman, Sergio; Motta, Maria Cristina M

    2015-01-01

    Mutualism is defined as a beneficial relationship for the associated partners and usually assumes that the symbiont number is controlled. Some trypanosomatid protozoa co-evolve with a bacterial symbiont that divides in coordination with the host in a way that results in its equal distribution between daughter cells. The mechanism that controls this synchrony is largely unknown, and its comprehension might provide clues to understand how eukaryotic cells evolved when acquiring symbionts that later became organelles. Here, we approached this question by studying the effects of inhibitors that affect the host exclusively in two symbiont-bearing trypanosomatids, Strigomonas culicis and Angomonas deanei. We found that inhibiting host protein synthesis using cycloheximide or host DNA replication using aphidicolin did not affect the duplication of bacterial DNA. Although the bacteria had autonomy to duplicate their DNA when host protein synthesis was blocked by cycloheximide, they could not complete cytokinesis. Aphidicolin promoted the inhibition of the trypanosomatid cell cycle in the G1/S phase, leading to symbiont filamentation in S. culicis but not in A. deanei. Treatment with camptothecin blocked the host protozoa cell cycle in the G2 phase and induced the formation of filamentous symbionts in both species. Oryzalin, which affects host microtubule polymerization, blocked trypanosomatid mitosis and abrogated symbiont division. Our results indicate that host factors produced during the cell division cycle are essential for symbiont segregation and may control the bacterial cell number.

  3. Endosymbiosis in trypanosomatid protozoa: the bacterium division is controlled during the host cell cycle

    PubMed Central

    Catta-Preta, Carolina M. C.; Brum, Felipe L.; da Silva, Camila C.; Zuma, Aline A.; Elias, Maria C.; de Souza, Wanderley; Schenkman, Sergio; Motta, Maria Cristina M.

    2015-01-01

    Mutualism is defined as a beneficial relationship for the associated partners and usually assumes that the symbiont number is controlled. Some trypanosomatid protozoa co-evolve with a bacterial symbiont that divides in coordination with the host in a way that results in its equal distribution between daughter cells. The mechanism that controls this synchrony is largely unknown, and its comprehension might provide clues to understand how eukaryotic cells evolved when acquiring symbionts that later became organelles. Here, we approached this question by studying the effects of inhibitors that affect the host exclusively in two symbiont-bearing trypanosomatids, Strigomonas culicis and Angomonas deanei. We found that inhibiting host protein synthesis using cycloheximide or host DNA replication using aphidicolin did not affect the duplication of bacterial DNA. Although the bacteria had autonomy to duplicate their DNA when host protein synthesis was blocked by cycloheximide, they could not complete cytokinesis. Aphidicolin promoted the inhibition of the trypanosomatid cell cycle in the G1/S phase, leading to symbiont filamentation in S. culicis but not in A. deanei. Treatment with camptothecin blocked the host protozoa cell cycle in the G2 phase and induced the formation of filamentous symbionts in both species. Oryzalin, which affects host microtubule polymerization, blocked trypanosomatid mitosis and abrogated symbiont division. Our results indicate that host factors produced during the cell division cycle are essential for symbiont segregation and may control the bacterial cell number. PMID:26082757

  4. Endosymbiosis in trypanosomatid protozoa: the bacterium division is controlled during the host cell cycle.

    PubMed

    Catta-Preta, Carolina M C; Brum, Felipe L; da Silva, Camila C; Zuma, Aline A; Elias, Maria C; de Souza, Wanderley; Schenkman, Sergio; Motta, Maria Cristina M

    2015-01-01

    Mutualism is defined as a beneficial relationship for the associated partners and usually assumes that the symbiont number is controlled. Some trypanosomatid protozoa co-evolve with a bacterial symbiont that divides in coordination with the host in a way that results in its equal distribution between daughter cells. The mechanism that controls this synchrony is largely unknown, and its comprehension might provide clues to understand how eukaryotic cells evolved when acquiring symbionts that later became organelles. Here, we approached this question by studying the effects of inhibitors that affect the host exclusively in two symbiont-bearing trypanosomatids, Strigomonas culicis and Angomonas deanei. We found that inhibiting host protein synthesis using cycloheximide or host DNA replication using aphidicolin did not affect the duplication of bacterial DNA. Although the bacteria had autonomy to duplicate their DNA when host protein synthesis was blocked by cycloheximide, they could not complete cytokinesis. Aphidicolin promoted the inhibition of the trypanosomatid cell cycle in the G1/S phase, leading to symbiont filamentation in S. culicis but not in A. deanei. Treatment with camptothecin blocked the host protozoa cell cycle in the G2 phase and induced the formation of filamentous symbionts in both species. Oryzalin, which affects host microtubule polymerization, blocked trypanosomatid mitosis and abrogated symbiont division. Our results indicate that host factors produced during the cell division cycle are essential for symbiont segregation and may control the bacterial cell number. PMID:26082757

  5. Regulation of the Calvin cycle for CO2 fixation as an example for general control mechanisms in metabolic cycles.

    PubMed

    Fridlyand, L E; Scheibe, R

    1999-08-01

    The theory of a metabolic cycle with the main portion of its intermediates remaining inside the cycle during one turnover has been developed. On this basis, the regulation of the Calvin cycle is analyzed. It is demonstrated that not only the reactions of non-equilibrium enzymes, as the carboxylation of ribulose 1,5-bisphosphate, but reactions that operate close to a thermodynamic equilibrium, especially the reduction of 3-phosphoglycerate and the transketolase reaction can significantly influence the total turnover period in the Calvin cycle. The role of compensating mechanisms in the maintenance of the photosynthesis rate upon changes of environmental conditions and of enzyme contents is analyzed for the Calvin cycle. It is shown that the change of the total quantity of the metabolites is one of the main self-regulated mechanisms in the Calvin cycle. A change of the ATP/ADP ratio can be used by the cell to maintain the CO2 assimilation rate, when the total quantity of the metabolites is changed. The developed analysis permits to explain some experimental data obtained with transgenic plants with restricted efflux of carbon from the chloroplasts.

  6. Concepts for Life Cycle Cost Control Required to Achieve Space Transportation Affordability and Sustainability

    NASA Technical Reports Server (NTRS)

    Rhodes, Russel E.; Zapata, Edgar; Levack, Daniel J. H.; Robinson, John W.; Donahue, Benjamin B.

    2009-01-01

    Cost control must be implemented through the establishment of requirements and controlled continually by managing to these requirements. Cost control of the non-recurring side of life cycle cost has traditionally been implemented in both commercial and government programs. The government uses the budget process to implement this control. The commercial approach is to use a similar process of allocating the non-recurring cost to major elements of the program. This type of control generally manages through a work breakdown structure (WBS) by defining the major elements of the program. If the cost control is to be applied across the entire program life cycle cost (LCC), the approach must be addressed very differently. A functional breakdown structure (FBS) is defined and recommended. Use of a FBS provides the visibifity to allow the choice of an integrated solution reducing the cost of providing many different elements of like function. The different functional solutions that drive the hardware logistics, quantity of documentation, operational labor, reliability and maintainability balance, and total integration of the entire system from DDT&E through the life of the program must be fully defined, compared, and final decisions made among these competing solutions. The major drivers of recurring cost have been identified and are presented and discussed. The LCC requirements must be established and flowed down to provide control of LCC. This LCC control will require a structured rigid process similar to the one traditionally used to control weight/performance for space transportation systems throughout the entire program. It has been demonstrated over the last 30 years that without a firm requirement and methodically structured cost control, it is unlikely that affordable and sustainable space transportation system LCC will be achieved.

  7. Multi-scale controls on spatial variability in river biogeochemical cycling

    NASA Astrophysics Data System (ADS)

    Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jennifer; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

    2016-04-01

    Excessive nutrient concentrations are common in surface waters and groundwaters in agricultural catchments worldwide. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical cycling rates can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are largely unknown. Here, we aimed to assess: 1) how differences in river geomorphological heterogeneity control solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load

  8. Mathematical Modeling as a Tool for Investigating Cell Cycle Control Networks

    PubMed Central

    Sible, Jill C.; Tyson, John J.

    2007-01-01

    Although not a traditional experimental “method,” mathematical modeling can provide a powerful approach for investigating complex cell signaling networks, such as those that regulate the eukaryotic cell division cycle. We describe here one approach to modeling the cell cycle based on expressing the rates of biochemical reactions in terms of nonlinear ordinary differential equations (ODEs). We discuss the steps and challenges in assigning numerical values to model parameters and the importance of experimental testing of a mathematical model. We illustrate this approach throughout with the simple and well-characterized example of mitotic cell cycles in frog egg extracts. To facilitate new modeling efforts, we describe several publicly available modeling environments, each with a collection of integrated programs for mathematical modeling. This review is intended to justify the place of mathematical modeling as a standard method for studying molecular regulatory networks and to guide the non-expert to initiate modeling projects to gain a systems-level perspective for complex control systems such as those governing the eukaryotic cell cycle. PMID:17189866

  9. Analysis of a Temperature-Controlled Exhaust Thermoelectric Generator During a Driving Cycle

    NASA Astrophysics Data System (ADS)

    Brito, F. P.; Alves, A.; Pires, J. M.; Martins, L. B.; Martins, J.; Oliveira, J.; Teixeira, J.; Goncalves, L. M.; Hall, M. J.

    2016-03-01

    Thermoelectric generators can be used in automotive exhaust energy recovery. As car engines operate under wide variable loads, it is a challenge to design a system for operating efficiently under these variable conditions. This means being able to avoid excessive thermal dilution under low engine loads and being able to operate under high load, high temperature events without the need to deflect the exhaust gases with bypass systems. The authors have previously proposed a thermoelectric generator (TEG) concept with temperature control based on the operating principle of the variable conductance heat pipe/thermosiphon. This strategy allows the TEG modules’ hot face to work under constant, optimized temperature. The variable engine load will only affect the number of modules exposed to the heat source, not the heat transfer temperature. This prevents module overheating under high engine loads and avoids thermal dilution under low engine loads. The present work assesses the merit of the aforementioned approach by analysing the generator output during driving cycles simulated with an energy model of a light vehicle. For the baseline evaporator and condenser configuration, the driving cycle averaged electrical power outputs were approximately 320 W and 550 W for the type-approval Worldwide harmonized light vehicles test procedure Class 3 driving cycle and for a real-world highway driving cycle, respectively.

  10. Ecological controls on water-cycle response to climate variability in deserts

    PubMed Central

    Scanlon, B. R.; Levitt, D. G.; Reedy, R. C.; Keese, K. E.; Sully, M. J.

    2005-01-01

    The impact of climate variability on the water cycle in desert ecosystems is controlled by biospheric feedback at interannual to millennial timescales. This paper describes a unique field dataset from weighing lysimeters beneath nonvegetated and vegetated systems that unequivocally demonstrates the role of vegetation dynamics in controlling water cycle response to interannual climate variability related to El Niño southern oscillation in the Mojave Desert. Extreme El Niño winter precipitation (2.3-2.5 times normal) typical of the U.S. Southwest would be expected to increase groundwater recharge, which is critical for water resources in semiarid and arid regions. However, lysimeter data indicate that rapid increases in vegetation productivity in response to elevated winter precipitation reduced soil water storage to half of that in a nonvegetated lysimeter, thereby precluding deep drainage below the root zone that would otherwise result in groundwater recharge. Vegetation dynamics have been controlling the water cycle in interdrainage desert areas throughout the U.S. Southwest, maintaining dry soil conditions and upward soil water flow since the last glacial period (10,000-15,000 yr ago), as shown by soil water chloride accumulations. Although measurements are specific to the U.S. Southwest, correlations between satellite-based vegetation productivity and elevated precipitation related to El Niño southern oscillation indicate this model may be applicable to desert basins globally. Understanding the two-way coupling between vegetation dynamics and the water cycle is critical for predicting how climate variability influences hydrology and water resources in water-limited landscapes. PMID:15837922

  11. Rapid alterations of cell cycle control proteins in human T lymphocytes in microgravity

    PubMed Central

    2012-01-01

    In our study we aimed to identify rapidly reacting gravity-responsive mechanisms in mammalian cells in order to understand if and how altered gravity is translated into a cellular response. In a combination of experiments using "functional weightlessness" provided by 2D-clinostats and real microgravity provided by several parabolic flight campaigns and compared to in-flight-1g-controls, we identified rapid gravity-responsive reactions inside the cell cycle regulatory machinery of human T lymphocytes. In response to 2D clinorotation, we detected an enhanced expression of p21 Waf1/Cip1 protein within minutes, less cdc25C protein expression and enhanced Ser147-phosphorylation of cyclinB1 after CD3/CD28 stimulation. Additionally, during 2D clinorotation, Tyr-15-phosphorylation occurred later and was shorter than in the 1 g controls. In CD3/CD28-stimulated primary human T cells, mRNA expression of the cell cycle arrest protein p21 increased 4.1-fold after 20s real microgravity in primary CD4+ T cells and 2.9-fold in Jurkat T cells, compared to 1 g in-flight controls after CD3/CD28 stimulation. The histone acetyltransferase (HAT) inhibitor curcumin was able to abrogate microgravity-induced p21 mRNA expression, whereas expression was enhanced by a histone deacetylase (HDAC) inhibitor. Therefore, we suppose that cell cycle progression in human T lymphocytes requires Earth gravity and that the disturbed expression of cell cycle regulatory proteins could contribute to the breakdown of the human immune system in space. PMID:22273506

  12. Ecological controls on water-cycle response to climate variability in deserts.

    PubMed

    Scanlon, B R; Levitt, D G; Reedy, R C; Keese, K E; Sully, M J

    2005-04-26

    The impact of climate variability on the water cycle in desert ecosystems is controlled by biospheric feedback at interannual to millennial timescales. This paper describes a unique field dataset from weighing lysimeters beneath nonvegetated and vegetated systems that unequivocally demonstrates the role of vegetation dynamics in controlling water cycle response to interannual climate variability related to El Nino southern oscillation in the Mojave Desert. Extreme El Nino winter precipitation (2.3-2.5 times normal) typical of the U.S. Southwest would be expected to increase groundwater recharge, which is critical for water resources in semiarid and arid regions. However, lysimeter data indicate that rapid increases in vegetation productivity in response to elevated winter precipitation reduced soil water storage to half of that in a nonvegetated lysimeter, thereby precluding deep drainage below the root zone that would otherwise result in groundwater recharge. Vegetation dynamics have been controlling the water cycle in interdrainage desert areas throughout the U.S. Southwest, maintaining dry soil conditions and upward soil water flow since the last glacial period (10,000-15,000 yr ago), as shown by soil water chloride accumulations. Although measurements are specific to the U.S. Southwest, correlations between satellite-based vegetation productivity and elevated precipitation related to El Nino southern oscillation indicate this model may be applicable to desert basins globally. Understanding the two-way coupling between vegetation dynamics and the water cycle is critical for predicting how climate variability influences hydrology and water resources in water-limited landscapes. PMID:15837922

  13. Sub-cycle optical phase control of nanotunnelling in the single-electron regime

    NASA Astrophysics Data System (ADS)

    Rybka, Tobias; Ludwig, Markus; Schmalz, Michael F.; Knittel, Vanessa; Brida, Daniele; Leitenstorfer, Alfred

    2016-10-01

    The high peak electric fields provided by single-cycle light pulses can be harnessed to manipulate and control charge motion in solid-state systems, resulting in electron emission out of metals and semiconductors or high harmonics generation in dielectrics. These processes are of a non-perturbative character and require precise reproducibility of the electric-field profile. Here, we vary the carrier-envelope phase of 6-fs-long near-infrared pulses with pJ-level energy to control electronic transport in a laterally confined nanoantenna with an 8 nm gap. Peak current densities of 50 MA cm-2 are achieved, corresponding to the transfer of individual electrons in a half-cycle period of 2 fs. The observed behaviours are made possible by the strong distortion of the effective tunnelling barrier due to the extreme electric fields that the nanostructure provides and sustains under sub-cycle optical biasing. Operating at room temperature and in a standard atmosphere, the performed experiments demonstrate a robust class of nanoelectronic switches gated by phase-locked optical transients of minute energy content.

  14. Control Activity in Support of NASA Turbine Based Combined Cycle (TBCC) Research

    NASA Technical Reports Server (NTRS)

    Stueber, Thomas J.; Vrnak, Daniel R.; Le, Dzu K.; Ouzts, Peter J.

    2010-01-01

    Control research for a Turbine Based Combined Cycle (TBCC) propulsion system is the current focus of the Hypersonic Guidance, Navigation, and Control (GN&C) discipline team. The ongoing work at the NASA Glenn Research Center (GRC) supports the Hypersonic GN&C effort in developing tools to aid the design of control algorithms to manage a TBCC airbreathing propulsion system during a critical operating period. The critical operating period being addressed in this paper is the span when the propulsion system transitions from one cycle to another, referred to as mode transition. One such tool, that is a basic need for control system design activities, is computational models (hereto forth referred to as models) of the propulsion system. The models of interest for designing and testing controllers are Control Development Models (CDMs) and Control Validation Models (CVMs). CDMs and CVMs are needed for each of the following propulsion system elements: inlet, turbine engine, ram/scram dual-mode combustor, and nozzle. This paper presents an overall architecture for a TBCC propulsion system model that includes all of the propulsion system elements. Efforts are under way, focusing on one of the propulsion system elements, to develop CDMs and CVMs for a TBCC propulsion system inlet. The TBCC inlet aerodynamic design being modeled is that of the Combined-Cycle Engine (CCE) Testbed. The CCE Testbed is a large-scale model of an aerodynamic design that was verified in a small-scale screening experiment. The modeling approach includes employing existing state-of-the-art simulation codes, developing new dynamic simulations, and performing system identification experiments on the hardware in the NASA GRC 10 by10-Foot Supersonic Wind Tunnel. The developed CDMs and CVMs will be available for control studies prior to hardware buildup. The system identification experiments on the CCE Testbed will characterize the necessary dynamics to be represented in CDMs for control design. These

  15. Cyclic fatigue analysis of rocket thrust chambers. Volume 2: Attitude control thruster high cycle fatigue

    NASA Technical Reports Server (NTRS)

    Miller, R. W.

    1974-01-01

    A finite element stress analysis was performed for the film cooled throat section of an attitude control thruster. The anlaysis employed the RETSCP finite element computer program. The analysis included thermal and pressure loads, and the effects of temperature dependent material properties, to determine the strain range corresponding to the thruster operating cycle. The configuration and operating conditions considered, correspond to a flightweight integrated thruster assembly which was thrust pulse tested. The computed strain range was used in conjuction with Haynes 188 Universal Slopes minimum life data to predict throat section fatigue life. The computed number of cycles to failure was greater than the number of pulses to which the thruster was experimentally subjected without failure.

  16. Emerging roles of E2Fs in cancer: an exit from cell cycle control

    PubMed Central

    Chen, Hui-Zi; Tsai, Shih-Yin; Leone, Gustavo

    2012-01-01

    Mutations of the retinoblastoma tumour suppressor gene (RB1) or components regulating the RB pathway have been identified in almost every human malignancy. The E2F transcription factors function in cell cycle control and are intimately regulated by RB. Studies of model organisms have revealed conserved functions for E2Fs during development, suggesting that the cancer-related proliferative roles of E2F family members represent a recent evolutionary adaptation. However, given that some human tumours have concurrent RB1 inactivation and E2F amplification and overexpression, we propose that there are alternative tumour-promoting activities for the E2F family, which are independent of cell cycle regulation. PMID:19851314

  17. Mathematical modeling as a tool for investigating cell cycle control networks.

    PubMed

    Sible, Jill C; Tyson, John J

    2007-02-01

    Although not a traditional experimental "method," mathematical modeling can provide a powerful approach for investigating complex cell signaling networks, such as those that regulate the eukaryotic cell division cycle. We describe here one modeling approach based on expressing the rates of biochemical reactions in terms of nonlinear ordinary differential equations. We discuss the steps and challenges in assigning numerical values to model parameters and the importance of experimental testing of a mathematical model. We illustrate this approach throughout with the simple and well-characterized example of mitotic cell cycles in frog egg extracts. To facilitate new modeling efforts, we describe several publicly available modeling environments, each with a collection of integrated programs for mathematical modeling. This review is intended to justify the place of mathematical modeling as a standard method for studying molecular regulatory networks and to guide the non-expert to initiate modeling projects in order to gain a systems-level perspective for complex control systems. PMID:17189866

  18. From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)

    NASA Astrophysics Data System (ADS)

    Cividini, D.; Lemarchand, D.; Chabaux, F.; Boutin, R.; Pierret, M.-C.

    2010-06-01

    There is a fast growing interest in understanding the coupling between mineralogical and biological processes responsible for the migration of elements through continental ecosystems. This issue has fundamental impacts at the soil/plant scale because it can explain the tight links between soil and plant development and at the watershed scale because it gives a direct access to the water quality. In the present study, we performed an extended investigation of the bio-geochemical cycle of boron, which is an element known to be suitable for investigating water/rock interactions and vegetation cycling. New B data are provided along the hydro-bio-geochemical continuum in a forest ecosystem (Strengbach basin, Vosges, France), from rainwaters down to the outlet of the basin including systematic analyses of throughfalls, soil solutions, springs and brooks scattered in the watershed. At the watershed scale, we evidence a relationship between the B isotopic composition of river waters and the weathering regime outlining a predominant control of the parent rock mineralogy on the B geochemical behavior. At the soil/plant scale, it appears that the B geochemical cycle is controlled by the vegetation cycling, which is characterized by an uncommon, easy to distinguish, B isotopic composition (δ 11B ranging from about +30‰ to +45‰). Each year the amount of B being involved in the vegetation cycle is about four times greater than that of B being exported out of the watershed. At 10 cm depth in soil, where the plant roots are expected to be the most active, we observe a marked seasonal oscillation of the B isotopic values, which is interpreted as resulting from the vegetation activity. A mass balance calculation based on the assumption that that 10B is preferentially accumulated in the biomass tends to indicate that the soil/plant system does not behave at steady state with respect to B. Because of the very distinct B isotopic signature of vegetation and minerals in soil, box

  19. Robust prevention of limit cycle for nonlinear control systems with parametric uncertainties both in the linear plant and nonlinearity.

    PubMed

    Wang, Yuan-Jay

    2007-10-01

    A new method is proposed to compute all feasible robust stabilizing controllers for preventing the generation of limit cycle of nonlinear control systems with parametric uncertainties both in the linear plant and nonlinearity. The describing function analysis method is employed to approximate the behaviors of the nonlinearity. The Kharitonov theorem is utilized to characterize parametric uncertainties in the linear plant and nonlinearity. Necessary conditions for limit cycles are established. Boundaries for the generation of limit cycle and boundaries for asymptotic stability are portrayed exploiting the stability equation method. The region for prescribed limit cycle behavior and the region for asymptotic stability are located. An admissible specification-oriented Kharitonov region is found directly on the controller parameter plane. The region is non-conservative and constitutes all of the feasible controller gain sets to achieve robust prevention of limit cycle for the considered uncertain nonlinear control systems. The way to tune the controller gains is suggested. Finally, for comparison purpose, two illustrative examples proposed in the literature are given to show how the proposed algorithm can be effectively applied to tune a robust controller to achieve a prescribed limit cycle behavior and accomplish robust limit cycle amplitude suppression and prevention.

  20. Geomorphic and substrate controls on spatial variability in river solute transport and biogeochemical cycling

    NASA Astrophysics Data System (ADS)

    Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

    2016-04-01

    Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be

  1. Magnetics and control in power electronics: I. Modeling of coupled inductors. II. One-cycle control of switching converters

    SciTech Connect

    Santi, E.

    1994-12-31

    Part I. For coupled-inductor and integrated-magnetics design it is of paramount importance to accurately model leakages. Air gap position has a dramatic effect on coupled-inductor characteristics. Improved reluctance models that capture this effect are proposed. For the most common coupled-inductor structures, i.e., UU and UI cores with windings on different legs, a simple model valid for any gap arrangement is proposed. The model has a single leakage reluctance that is constant for a given core geometry and can be determined from a single set of measurements. A method to estimate this reluctance from core geometry is also suggested. A new coupled-inductor structure that achieves quasi-zero current riple without need for turns ratio adjustment is introduced. Part 2. The concept of One-Cycle control has recently been proposed. The generality of this control technique is demonstrated through description of its implementation for different DC-DC switching converters. It is a nonlinear control technique with significant advantages in terms of rejection of line perturbation, speed of response and insensitivity to circuit parameters. Until now, no stability analysis was available and, under certain conditions, instability was observed. In this paper a stability analysis of a One-Cycle controlled Cuk converter (a fourth order system) is performed, which shows that stability depends on the value of parasitic elements. A modification of the control to eliminate steady-state output voltage error is proposed. Finally, a modification of the control that ensures stability independently of the value of parasitic elements is suggested. All theoretical results are experimentally verified.

  2. Rankine cycle condenser pressure control using an energy conversion device bypass valve

    DOEpatents

    Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

    2014-04-01

    The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

  3. Exfoliation Propensity of Oxide Scale in Heat Exchangers Used for Supercritical CO2 Power Cycles

    SciTech Connect

    Sabau, Adrian S; Shingledecker, John P.; Kung, Steve; Wright, Ian G.; Nash, Jim

    2016-01-01

    Supercritical CO2 (sCO2) Brayton cycle systems offer the possibility of improved efficiency in future fossil energy power generation plants operating at temperatures of 650 C and above. As there are few data on the oxidation/corrosion behavior of structural alloys in sCO2 at these temperatures, modeling to predict the propensity for oxide exfoliation is not well developed, thus hindering materials selection for these novel cycles. The ultimate goal of this effort is to provide needed data on scale exfoliation behavior in sCO2 for confident alloy selection. To date, a model developed by ORNL and EPRI for the exfoliation of oxide scales formed on boiler tubes in high-temperature, high-pressure steam has proven useful for managing exfoliation in conventional steam plants. A major input provided by the model is the ability to predict the likelihood of scale failure and loss based on understanding of the evolution of the oxide morphologies and the conditions that result in susceptibility to exfoliation. This paper describes initial steps taken to extend the existing model for exfoliation of steam-side oxide scales to sCO2 conditions. The main differences between high-temperature, high-pressure steam and sCO2 that impact the model involve (i) significant geometrical differences in the heat exchangers, ranging from standard pressurized tubes seen typically in steam-producing boilers to designs for sCO2 that employ variously-curved thin walls to create shaped flow paths for extended heat transfer area and small channel cross-sections to promote thermal convection and support pressure loads; (ii) changed operating characteristics with sCO2 due to the differences in physical and thermal properties compared to steam; and (iii) possible modification of the scale morphologies, hence properties that influence exfoliation behavior, due to reaction with carbon species from sCO2. The numerical simulations conducted were based on an assumed sCO2 operating schedule and several

  4. Integrative Analysis of Cell Cycle Control in Budding YeastD⃞

    PubMed Central

    Chen, Katherine C.; Calzone, Laurence; Csikasz-Nagy, Attila; Cross, Frederick R.; Novak, Bela; Tyson, John J.

    2004-01-01

    The adaptive responses of a living cell to internal and external signals are controlled by networks of proteins whose interactions are so complex that the functional integration of the network cannot be comprehended by intuitive reasoning alone. Mathematical modeling, based on biochemical rate equations, provides a rigorous and reliable tool for unraveling the complexities of molecular regulatory networks. The budding yeast cell cycle is a challenging test case for this approach, because the control system is known in exquisite detail and its function is constrained by the phenotypic properties of >100 genetically engineered strains. We show that a mathematical model built on a consensus picture of this control system is largely successful in explaining the phenotypes of mutants described so far. A few inconsistencies between the model and experiments indicate aspects of the mechanism that require revision. In addition, the model allows one to frame and critique hypotheses about how the division cycle is regulated in wild-type and mutant cells, to predict the phenotypes of new mutant combinations, and to estimate the effective values of biochemical rate constants that are difficult to measure directly in vivo. PMID:15169868

  5. Thermal Cycling of Thermal Control Paints on Carbon-Carbon and Carbon-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2006-01-01

    Carbon-carbon composites and carbon-polyimide composites are being considered for space radiator applications owing to their light weight and high thermal conductivity. For those radiator applications where sunlight will impinge on the surface, it will be necessary to apply a white thermal control paint to minimize solar absorptance and enhance infrared emittance. Several currently available white thermal control paints were applied to candidate carbon-carbon and carbon-polyimide composites and were subjected to vacuum thermal cycling in the range of -100 C to +277 C. The optical properties of solar absorptance and infrared emittance were evaluated before and after thermal cycling. In addition, adhesion of the paints was evaluated utilizing a tape test. The test matrix included three composites: resin-derived carbon-carbon and vapor infiltrated carbon-carbon, both reinforced with pitch-based P-120 graphite fibers, and a polyimide composite reinforced with T-650 carbon fibers, and three commercially available white thermal control paints: AZ-93, Z-93-C55, and YB-71P.

  6. Water loss control using pressure management: life-cycle energy and air emission effects.

    PubMed

    Stokes, Jennifer R; Horvath, Arpad; Sturm, Reinhard

    2013-10-01

    Pressure management is one cost-effective and efficient strategy for controlling water distribution losses. This paper evaluates the life-cycle energy use and emissions for pressure management zones in Philadelphia, Pennsylvania, and Halifax, Nova Scotia. It compares water savings using fixed-outlet and flow-modulated pressure control to performance without pressure control, considering the embedded electricity and chemical consumption in the lost water, manufacture of pipe and fittings to repair breaks caused by excess pressure, and pressure management. The resulting energy and emissions savings are significant. The Philadelphia and Halifax utilities both avoid approximately 130 million liters in water losses annually using flow-modulated pressure management. The conserved energy was 780 GJ and 1900 GJ while avoided greenhouse gas emissions were 50 Mg and 170 Mg a year by Philadelphia and Halifax, respectively. The life-cycle financial and environmental performance of pressure management systems compares favorably to the traditional demand management strategy of installing low-flow toilets. The energy savings may also translate to cost-effective greenhouse gas emission reductions depending on the energy mix used, an important advantage in areas where water and energy are constrained and/or expensive and greenhouse gas emissions are regulated as in California, for example.

  7. Analysis of Factors Controlling Cell Cycle that Can Be Synchronized Nondestructively During Root Cap Development

    SciTech Connect

    Martha Hawes

    2011-02-04

    Publications and presentations during the final funding period, including progress in defining the substrate specificity, the primary goal of the project, are listed below. Both short-term and long-term responses mediated by PsUGT1 have been characterized in transgenic or mutant pea, alfalfa, and Arabidopsis with altered expression of PsUGT1. Additional progress includes evaluation of the relationship between control of the cell cycle by PsUGT1 and other glycosyltransferase and glycosidase enzymes that are co-regulated in the legume root cap during the onset of mitosis and differentiation. Transcriptional profiling and multidimensional protein identification technology ('MudPIT') have been used to establish the broader molecular context for the mechanism by which PsUGT1 controls cell cycle in response to environmental signals. A collaborative study with the Norwegian Forest Research Institute (who provided $10,000.00 in supplies and travel funds for collaborator Dr. Toril Eldhuset to travel to Arizona and Dr. H. H. Woo to travel to Norway) made it possible to establish that the inducible root cap system for studying carbohydrate synthesis and solubilization is expressed in gymnosperm as well as angiosperm species. This discovery provides an important tool to amplify the potential applications of the research in defining conserved cell cycle machinery across a very broad range of plant species and habitats. The final work, published during 2009, revealed an additional surprising parallel with mammalian immune responses: The cells whose production is controlled by PsUGT1 appear to function in a manner which is analogous to that of white blood cells, by trapping and killing in an extracellular manner. This may explain why mutation within the coding region of PsUGT1 and its homolog in humans (UGT1) is lethal to plants and animals. The work has been the subject of invited reviews. A postdoctoral fellow, eight undergraduate students, four M.S. students and three Ph

  8. Menstrual Cycle Control in Female Astronauts and the Associated Risk of Venous Thromboembolism

    NASA Technical Reports Server (NTRS)

    Jain, Varsha; Wotring, Virginia

    2015-01-01

    Venous thromboembolism (VTE) is a common and serious condition affecting approximately 1-2 per 1000 people in the USA every year. There have been no documented case reports of VTE in female astronauts during spaceflight in the published literature. Some female astronauts use hormonal contraception to control their menstrual cycles and it is currently unknown how this affects their risk of VTE. Current terrestrial risk prediction models do not account for the spaceflight environment and the physiological changes associated with it. We therefore aim to estimate a specific risk score for female astronauts who are taking hormonal contraception for menstrual cycle control, to deduce whether they are at an elevated risk of VTE. A systematic review of the literature was conducted in order to identify and quantify known terrestrial risk factors for VTE. Studies involving analogues for the female astronaut population were also reviewed, for example, military personnel who use the oral contraceptive pill for menstrual suppression. Well known terrestrial risk factors, for example, obesity or smoking would not be applicable to our study population as these candidates would have been excluded during astronaut selection processes. Other risk factors for VTE include hormonal therapy, lower limb paralysis, physical inactivity, hyperhomocysteinemia, low methylfolate levels and minor injuries, all of which potentially apply to crew members LSAH data will be assessed to identify which of these risk factors are applicable to our astronaut population. Using known terrestrial risk data, an overall estimated risk of VTE for female astronauts using menstrual cycle control methods will therefore be calculated. We predict this will be higher than the general population but not significantly higher requiring thromboprophylaxis. This study attempts to delineate what is assumed to be true of our astronaut population, for example, they are known to be a healthy fit cohort of individuals, and

  9. Classical linear-control analysis applied to business-cycle dynamics and stability

    NASA Technical Reports Server (NTRS)

    Wingrove, R. C.

    1983-01-01

    Linear control analysis is applied as an aid in understanding the fluctuations of business cycles in the past, and to examine monetary policies that might improve stabilization. The analysis shows how different policies change the frequency and damping of the economic system dynamics, and how they modify the amplitude of the fluctuations that are caused by random disturbances. Examples are used to show how policy feedbacks and policy lags can be incorporated, and how different monetary strategies for stabilization can be analytically compared. Representative numerical results are used to illustrate the main points.

  10. The tricarboxylic acid cycle in Shewanella oneidensis is independent of Fur and RyhB control

    SciTech Connect

    Yang, Yunfeng; McCue, Lee Ann; Parsons, Andrea B.; Feng, Sheng; Zhou, Jizhong

    2010-10-26

    It is well established in E. coli and Vibrio cholerae that strains harboring mutations in the ferric uptake regulator gene (fur) are unable to utilize tricarboxylic acid (TCA) compounds, due to the down-regulation of key TCA cycle enzymes, such as AcnA and SdhABCD. This down-regulation is mediated by a Fur-regulated small regulatory RNA named RyhB. In this study, we showed that a fur deletion mutant of the γ-proteobacterium S. oneidensis could utilize TCA compounds. In addition, expression of the TCA cycle genes acnA and sdhA was not down-regulated in the mutant. To explore this observation further, we identified a ryhB gene in Shewanella species and demonstrated its expression experimentally. Further experiments suggested that RyhB was up-regulated in fur mutant, but that AcnA and SdhA were not controlled by RyhB. This work delineates an important difference of the Fur-RyhB regulatory cycle between S. oneidensis and other γ-proteobacteria.

  11. The tricarboxylic acid cycle in Shewanella oneidensis is independent of Fur and RyhB control

    SciTech Connect

    Yang, Yunfeng; McCue, Lee Ann; Parsons, Andrea; Feng, Sheng; Zhou, Jizhong

    2010-01-01

    Background: It is well established in E. coli and Vibrio cholerae that strains harboring mutations in the ferric uptake regulator gene (fur) are unable to utilize tricarboxylic acid (TCA) compounds, due to the down-regulation of key TCA cycle enzymes, such as AcnA and SdhABCD. This down-regulation is mediated by a Fur-regulated small regulatory RNA named RyhB. It is unclear in the g-proteobacterium S. oneidensis whether TCA is also regulated by Fur and RyhB. Results: In the present study, we showed that a fur deletion mutant of S. oneidensis could utilize TCA compounds. Consistently, expression of the TCA cycle genes acnA and sdhA was not down-regulated in the mutant. To explore this observation further, we identified a ryhB gene in Shewanella species and experimentally demonstrated the gene expression. Further experiments suggested that RyhB was up-regulated in fur mutant, but that AcnA and SdhA were not controlled by RyhB. Conclusions: These cumulative results delineate an important difference of the Fur-RyhB regulatory cycle between S. oneidensis and other g-proteobacteria. This work represents a step forward for understanding the unique regulation in S. oneidensis.

  12. The next generation of automobile emissions reduction: Innovative control of off-cycle emissions

    SciTech Connect

    Potter, T F; Lyons, C E

    1995-03-01

    Innovative heat management technologies can reduce emissions from cars by an order of magnitude. Substantial reductions would be realized during cold starts and in evaporative emissions. Such improvements result from a new class of variable-conductance steel vacuum insulations that insulate during one time period and take advantage of beneficial thermal conditions during another. Around a catalytic converter, for example, such control allows heat from one driving cycle to catalyze engine-out emissions occurring at the beginning of the next cycle. As with other more efficient uses of heat in automobiles, reduced complexity and cost are likely compared to supplemental catalyst heating systems. In a similar way, thermal cycling of fuel and the resulting vapor release can be reduced or avoided. Urban air quality could be greatly improved by the wide availability of vehicles using these technologies early in the next century. This paper presents analyses and prototype data supporting the design, operation, and rapid market penetration of internal combustion engine vehicles with significantly lower emissions based on such improved thermal management. Potential implications for fleet emissions are discussed.

  13. Control of the bovine estrous cycle with melengestrol acetate (MGA): a review.

    PubMed

    Patterson, D J; Kiracofe, G H; Stevenson, J S; Corah, L R

    1989-08-01

    Expanded use of artificial insemination in the beef cattle industry depends on successful application of treatments designed to synchronize estrus. Regulation of estrous cycles is associated with control of the corpus luteum (CL), whose life span and secretory activity are subject to trophic and lytic mechanisms. The advantages of melengestrol acetate (MGA) in estrous synchronization incorporate ease of administration, lower cost relative to other estrous synchronization products, and potential for use to induce estrus in prepubertal heifers. Treatments first designed to synchronize estrous cycles of normally cycling heifers by feeding MGA were imposed daily for 14 to 18 d at levels of .5 to 1 mg. The minimal daily effective dose required to inhibit ovulation was .42 mg. Longer feeding periods of MGA were associated with low fertility at the first synchronized estrus, but at the second estrus, conception was normal. Low fertility at the synchronized estrus resulted in development of alternative treatment practices, which combined feeding of MGA with injections or implants of estradiol-17 beta, estradiol cypionate, luteinizing hormone, human chorionic gonadotropin, pregnant mare serum gonadotropin, or oxytocin. Estrus was synchronized after MGA and estradiol-17 beta or estradiol cypionate treatments, but fertility was low. Short-term feeding of MGA (5 to 7 d) combined with prostaglandin F2 alpha or its analogs (PGF) on the last day of MGA reduced fertility at the synchronized estrus. The reduced conception at first service occurred in animals that began treatment after d 12 of the estrous cycle. However, feeding MGA for 14 d and then injecting PGF 17 d later avoided problems with reduced conception. Fertility of animals after this treatment was similar to that of contemporaries synchronized with Syncro-Mate-B. However, the length of the treatment period creates a need for increased management and may extend management beyond practical limits. Further research is

  14. Diurnal cycles control the fate of contaminants at an Andean river confluence impacted by legacy mining

    NASA Astrophysics Data System (ADS)

    Pasten, P.; Guerra, P. A.; Simonson, K.; Bonilla, C.; Pizarro, G. E.; Escauriaza, C. R.; González, C.

    2014-12-01

    The importance of hydrologic-geochemical interactions in arid environments is a controlling factor in quality and quantity of water available for human consumption and agriculture. When acid drainage affects these watersheds, water quality is gravely degraded. Despite its effect on watersheds, the relationship between time changes in hydrological variables and water quality in arid regions has not been studied thoroughly. Temporal variations in acid drainage can control when the transport of toxic elements is increased. We performed field work at the Azufre River (pH 2, E.C~10.9 mS/cm) and Caracarani River (pH 8.7, E.C~1.2 mS/cm) confluence, located in the Northern Chilean Altiplano (at 4000 m asl). We registered stream flowrates (total flowrate~430 L/s), temperature and electric conductivity (E.C) hourly using in-stream data loggers during one year. We also measured turbidity and pH during one field survey at different distances from the junction, as a proxy of the formation of iron-aluminum particles that cycle trace elements in these environments. We found turbidity-pH diurnal cycles were caused by upstream hourly changes in upstream flowrate: when the Caracarani River flowrate reached its daily peak, particle formation occurred, while the dissolution of particles occurred when the Azufre River reached its maximum value. This last process occurred due to upstream freeze-thaw cycles. This study shows how the dynamics of natural confluences determines chemical transport. The formation of particles enriched in toxic elements can promote settling as a natural attenuation process, while their dissolution will produce their release and transport long distances downstream. It is important to consider time as an important variable in water quality monitoring and in water management infrastructure where pulses of contamination can have potentially negative effects in its use. Acknowledgements: Funding was provided by "Proyecto Fondecyt 1130936" and "CONICYT

  15. Parallel operation of two Brayton-cycle alternators with parasitic speed controllers

    NASA Technical Reports Server (NTRS)

    Perz, D. A.

    1972-01-01

    The experimental paralleling characteristics of two 1200 Hz Brayton-cycle alternators are presented. Since the Brayton power conversion system uses electric speed controllers, the paralleling requirements are somewhat different from those for conventional ground-based systems. Results include the transient effects of synchronizing the two alternators with various phase-angle, voltage, and frequency differences. Based on these results, the effects of synchronizing differences can be defined, and adjustment requirements of the parasitic speed controllers during synchronizing can be established. Data indicate that parasitically loaded alternators are able to parallel over a wide range of synchronizing differences. However, equilibrium could not be reached in extreme cases where alternator load differences were great and, at the same time, the phase-angle error was large (150 deg or more).

  16. Measurement control design and performance assessment in the Integral Fast Reactor fuel cycle

    SciTech Connect

    Orechwa, Y.; Bucher, R.G.

    1994-08-01

    The Integral Fast Reactor (IFR)--consisting of a metal fueled and liquid metal cooled reactor together with an attendant fuel cycle facility (FCF)--is currently undergoing a phased demonstration of the closed fuel cycle at Argonne National Laboratory. The recycle technology is pyrometalurgical based with incomplete fission product separation and all transuranics following plutonium for recycle. The equipment operates in batch mode at 500 to 1,300 C. The materials are highly radioactive and pyrophoric, thus the FCF requires remote operation. Central to the material control and accounting system for the FCF are the balances for mass measurements. The remote operation of the balances limits direct adjustment. The radiation environment requires that removal and replacement of the balances be minimized. The uniqueness of the facility precludes historical data for design and performance assessment. To assure efficient operation of the facility, the design of the measurement control system has called for procedures which assess the performance of the balances in great detail and will support capabilities for the correction of systematic changes in the performance of the balances through software.

  17. Control of Cell Cycle Entry and Apoptosis in B Lymphocytes Infected by Epstein-Barr Virus

    PubMed Central

    Spender, Lindsay C.; Cannell, Emma J.; Hollyoake, Martine; Wensing, Barbara; Gawn, Jonathan M.; Brimmell, Matthew; Packham, Graham; Farrell, Paul J.

    1999-01-01

    Infection of human B cells with Epstein-Barr virus (EBV) results in activation of the cell cycle and cell growth. To interpret the mechanisms by which EBV activates the cell, we have assayed many proteins involved in control of the G0 and G1 phases of the cell cycle and regulation of apoptosis. In EBV infection most of the changes, including the early induction of cyclin D2, are dependent on expression of EBV genes, but an alteration in the E2F-4 profile was partly independent of viral gene expression, presumably occurring in response to signal transduction activated when the virus binds to its receptor, CD21. By comparing the expression of genes controlling apoptosis, including those encoding several members of the BCL-2 family of proteins, the known relative resistance of EBV-immortalized B-cell lines to apoptosis induced by low serum was found to correlate with expression of both BCL-2 and A20. A20 can be regulated by the NF-κB transcription factor, which is known to be activated by the EBV LMP-1 protein. Quantitative assays demonstrated a direct temporal relationship between LMP-1 protein levels and active NF-κB during the time course of infection. PMID:10233927

  18. Dynamic localization of a cytoplasmic signal transduction response regulator controls morphogenesis during the Caulobacter cell cycle

    PubMed Central

    Jacobs, Christine; Hung, Dean; Shapiro, Lucy

    2001-01-01

    We present evidence that a bacterial signal transduction cascade that couples morphogenesis with cell cycle progression is regulated by dynamic localization of its components. Previous studies have implicated two histidine kinases, DivJ and PleC, and the response regulator, DivK, in the regulation of morphogenesis in the dimorphic bacterium Caulobacter crescentus. Here, we show that the cytoplasmic response regulator, DivK, exhibits a dynamic, cyclical localization that culminates in asymmetric distribution of DivK within the two cell types that are characteristic of the Caulobacter cell cycle; DivK is dispersed throughout the cytoplasm of the progeny swarmer cell and is localized to the pole of the stalked cell. The membrane-bound DivJ and PleC histidine kinases, which are asymmetrically localized at the opposite poles of the predivisional cell, control the temporal and spatial localization of DivK. DivJ mediates DivK targeting to the poles whereas PleC controls its release from one of the poles at times and places that are consistent with the activities and location of DivJ and PleC in the late predivisional cell. Thus, dynamic changes in subcellular location of multiple components of a signal transduction cascade may constitute a novel mode of prokaryotic regulation to generate and maintain cellular asymmetry. PMID:11274434

  19. Experimental opto-mechanics with levitated nanoparticles: towards quantum control and thermodynamic cycles (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kiesel, Nikolai; Blaser, Florian; Delic, Uros; Grass, David; Dechant, Andreas; Lutz, Eric; Bathaee, Marzieh; Aspelmeyer, Markus

    2015-08-01

    Combining optical levitation and cavity optomechanics constitutes a promising approach to prepare and control the motional quantum state of massive objects (>10^9 amu). This, in turn, would represent a completely new type of light-matter interface and has, for example, been predicted to enable experimental tests of macrorealistic models or of non-Newtonian gravity at small length scales. Such ideas have triggered significant experimental efforts to realizing such novel systems. To this end, we have recently successfully demonstrated cavity-cooling of a levitated sub-micron silica particle in a classical regime at a pressure of approximately 1mbar. Access to higher vacuum of approx. 10^-6 mbar has been demonstrated using 3D-feedback cooling in optical tweezers without cavity-coupling. Here we will illustrate our strategy towards trapping, 3D-cooling and quantum control of nanoparticles in ultra-high vacuum using cavity-based feedback cooling methods and clean particle loading with hollow-core photonic crystal fibers. We will also discuss the current experimental progress both in 3D-cavity cooling and HCPCF-based transport of nanoparticles. As yet another application of cavity-controlled levitated nanoparticles we will show how to implement a thermodynamic Sterling cycle operating in the underdamped regime. We present optimized protocols with respect to efficiency at maximum power in this little explored regime. We also show that the excellent level of control in our system will allow reproducing all relevant features of such optimized protocols. In a next step, this will enable studies of thermodynamics cycles in a regime where the quantization of the mechanical motion becomes relevant.

  20. Antecedent acute cycling exercise affects attention control: an ERP study using attention network test.

    PubMed

    Chang, Yu-Kai; Pesce, Caterina; Chiang, Yi-Te; Kuo, Cheng-Yuh; Fong, Dong-Yang

    2015-01-01

    The purpose of this study was to investigate the after-effects of an acute bout of moderate intensity aerobic cycling exercise on neuroelectric and behavioral indices of efficiency of three attentional networks: alerting, orienting, and executive (conflict) control. Thirty young, highly fit amateur basketball players performed a multifunctional attentional reaction time task, the attention network test (ANT), with a two-group randomized experimental design after an acute bout of moderate intensity spinning wheel exercise or without antecedent exercise. The ANT combined warning signals prior to targets, spatial cueing of potential target locations and target stimuli surrounded by congruent or incongruent flankers, which were provided to assess three attentional networks. Event-related brain potentials and task performance were measured during the ANT. Exercise resulted in a larger P3 amplitude in the alerting and executive control subtasks across frontal, central and parietal midline sites that was paralleled by an enhanced reaction speed only on trials with incongruent flankers of the executive control network. The P3 latency and response accuracy were not affected by exercise. These findings suggest that after spinning, more resources are allocated to task-relevant stimuli in tasks that rely on the alerting and executive control networks. However, the improvement in performance was observed in only the executively challenging conflict condition, suggesting that whether the brain resources that are rendered available immediately after acute exercise translate into better attention performance depends on the cognitive task complexity.

  1. Cyclin D1-CDK4 Controls Glucose Metabolism Independently of Cell Cycle Progression

    PubMed Central

    Lee, Yoonjin; Dominy, John E.; Choi, Yoon Jong; Jurczak, Michael; Tolliday, Nicola; Camporez, Joao Paulo; Chim, Helen; Lim, Ji-Hong; Ruan, Hai-Bin; Yang, Xiaoyong; Vazquez, Francisca; Sicinski, Piotr; Shulman, Gerald I.; Puigserver, Pere

    2014-01-01

    Insulin constitutes a major evolutionarily conserved hormonal axis for maintaining glucose homeostasis1-3; dysregulation of this axis causes diabetes2,4. PGC-1α links insulin signaling to the expression of glucose and lipid metabolic genes5-7. GCN5 acetylates PGC-1α and suppresses its transcriptional activity, whereas SIRT1 deacetylates and activates PGC-1α8,9. Although insulin is a mitogenic signal in proliferative cells10,11, whether components of the cell cycle machinery contribute to insulin’s metabolic action is poorly understood. Herein, we report that insulin activates cyclin D1-CDK4, which, in turn, increases GCN5 acetyltransferase activity and suppresses hepatic glucose production independently of cell cycle progression. Through a cell-based high throughput chemical screen, we identified a CDK4 inhibitor that potently decreases PGC-1α acetylation. Insulin/GSK3β signaling induces cyclin D1 protein stability via sequestering cyclin D1 in the nucleus. In parallel, dietary amino acids increase hepatic cyclin D1 mRNA transcripts. Activated cyclin D1-CDK4 kinase phosphorylates and activates GCN5, which then acetylates and inhibits PGC-1α activity on gluconeogenic genes. Loss of hepatic cyclin D1 results in increased gluconeogenesis and hyperglycemia. In diabetic models, cyclin D1-CDK4 is chronically elevated and refractory to fasting/feeding transitions; nevertheless further activation of this kinase normalizes glycemia. Our findings show that insulin uses components of the cell cycle machinery in post-mitotic cells to control glucose homeostasis independently of cell division. PMID:24870244

  2. Designing responsive pattern generators: stable heteroclinic channel cycles for modeling and control.

    PubMed

    Horchler, Andrew D; Daltorio, Kathryn A; Chiel, Hillel J; Quinn, Roger D

    2015-04-01

    A striking feature of biological pattern generators is their ability to respond immediately to multisensory perturbations by modulating the dwell time at a particular phase of oscillation, which can vary force output, range of motion, or other characteristics of a physical system. Stable heteroclinic channels (SHCs) are a dynamical architecture that can provide such responsiveness to artificial devices such as robots. SHCs are composed of sequences of saddle equilibrium points, which yields exquisite sensitivity. The strength of the vector fields in the neighborhood of these equilibria determines the responsiveness to perturbations and how long trajectories dwell in the vicinity of a saddle. For SHC cycles, the addition of stochastic noise results in oscillation with a regular mean period. In this paper, we parameterize noise-driven Lotka-Volterra SHC cycles such that each saddle can be independently designed to have a desired mean sub-period. The first step in the design process is an analytic approximation, which results in mean sub-periods that are within 2% of the specified sub-period for a typical parameter set. Further, after measuring the resultant sub-periods over sufficient numbers of cycles, the magnitude of the noise can be adjusted to control the mean period with accuracy close to that of the integration step size. With these relationships, SHCs can be more easily employed in engineering and modeling applications. For applications that require smooth state transitions, this parameterization permits each state's distribution of periods to be independently specified. Moreover, for modeling context-dependent behaviors, continuously varying inputs in each state dimension can rapidly precipitate transitions to alter frequency and phase. PMID:25712192

  3. Sand dune patterns on Titan controlled by long-term climate cycles

    NASA Astrophysics Data System (ADS)

    Ewing, Ryan C.; Hayes, Alex G.; Lucas, Antoine

    2015-01-01

    Linear sand dunes cover the equatorial latitudes of Saturn's moon Titan and are shaped by global wind patterns. These dunes are thought to reflect present-day diurnal, tidal and seasonal winds, but climate models have failed to reproduce observed dune morphologies with these wind patterns. Dunes diagnostic of a specific wind or formative timescale have remained elusive. Here we analyse radar imagery from NASA's Cassini spacecraft and identify barchan, star and reoriented dunes in sediment-limited regions of Titan's equatorial dune fields that diverge by 23° on average from the orientation of linear dunes. These morphologies imply shifts in wind direction and sediment availability. Using a numerical model, we estimate that the observed reorientation of dune crests to a change in wind direction would have taken around 3,000 Saturn years (1 Saturn year ~ 29.4 Earth years) or longer--a timescale that exceeds diurnal, seasonal or tidal cycles. We propose that shifts in winds and sediment availability are the product of long-term climate cycles associated with variations in Saturn's orbit. Orbitally controlled landscape evolution--also proposed to explain the distribution of Titan's polar lakes--implies a dune-forming climate on equatorial Titan that is analogous to Earth.

  4. Hydrologic control of carbon cycling and aged carbon discharge in the Congo River basin

    NASA Astrophysics Data System (ADS)

    Schefuß, Enno; Eglinton, Timothy I.; Spencer-Jones, Charlotte L.; Rullkötter, Jürgen; de Pol-Holz, Ricardo; Talbot, Helen M.; Grootes, Pieter M.; Schneider, Ralph R.

    2016-09-01

    The age of organic material discharged by rivers provides information about its sources and carbon cycling processes within watersheds. Although elevated ages in fluvially transported organic matter are usually explained by erosion of soils and sedimentary deposits, it is commonly assumed that mainly young organic material is discharged from flat tropical watersheds due to their extensive plant cover and rapid carbon turnover. Here we present compound-specific radiocarbon data of terrigenous organic fractions from a sedimentary archive offshore the Congo River, in conjunction with molecular markers for methane-producing land cover reflecting wetland extent. We find that the Congo River has been discharging aged organic matter for several thousand years, with apparently increasing ages from the mid- to the Late Holocene. This suggests that aged organic matter in modern samples is concealed by radiocarbon from atmospheric nuclear weapons testing. By comparison to indicators for past rainfall changes we detect a systematic control of organic matter sequestration and release by continental hydrology, mediating temporary carbon storage in wetlands. As aridification also leads to exposure and rapid remineralization of large amounts of previously stored labile organic matter, we infer that this process may cause a profound direct climate feedback that is at present underestimated in carbon cycle assessments.

  5. Enforcing temporal control of maternal mRNA translation during oocyte cell-cycle progression.

    PubMed

    Arumugam, Karthik; Wang, Yiying; Hardy, Linda L; MacNicol, Melanie C; MacNicol, Angus M

    2010-01-20

    Meiotic cell-cycle progression in progesterone-stimulated Xenopus oocytes requires that the translation of pre-existing maternal mRNAs occur in a strict temporal order. Timing of translation is regulated through elements within the mRNA 3' untranslated region (3' UTR), which respond to cell cycle-dependant signalling. One element that has been previously implicated in the temporal control of mRNA translation is the cytoplasmic polyadenylation element (CPE). In this study, we show that the CPE does not direct early mRNA translation. Rather, early translation is directed through specific early factors, including the Musashi-binding element (MBE) and the MBE-binding protein, Musashi. Our findings indicate that although the cyclin B5 3' UTR contains both CPEs and an MBE, the MBE is the critical regulator of early translation. The cyclin B2 3' UTR contains CPEs, but lacks an MBE and is translationally activated late in maturation. Finally, utilizing antisense oligonucleotides to attenuate endogenous Musashi synthesis, we show that Musashi is critical for the initiation of early class mRNA translation and for the subsequent activation of CPE-dependant mRNA translation.

  6. Deregulated expression of circadian clock and clock-controlled cell cycle genes in chronic lymphocytic leukemia.

    PubMed

    Rana, Sobia; Munawar, Mustafa; Shahid, Adeela; Malik, Meera; Ullah, Hafeez; Fatima, Warda; Mohsin, Shahida; Mahmood, Saqib

    2014-01-01

    Circadian rhythms are endogenous and self-sustained oscillations of multiple biological processes with approximately 24-h rhythmicity. Circadian genes and their protein products constitute the molecular components of the circadian oscillator that form positive/negative feedback loops and generate circadian rhythms. The circadian regulation extends from core clock genes to various clock-controlled genes that include various cell cycle genes. Aberrant expression of circadian clock genes, therefore, may lead to genomic instability and accelerated cellular proliferation potentially promoting carcinogenesis. The current study encompasses the investigation of simultaneous expression of four circadian clock genes (Bmal1, Clock, Per1 and Per2) and three clock-controlled cell cycle genes (Myc, Cyclin D1 and Wee1) at mRNA level and determination of serum melatonin levels in peripheral blood samples of 37 CLL (chronic lymphocytic leukemia) patients and equal number of age- and sex-matched healthy controls in order to indicate association between deregulated circadian clock and manifestation of CLL. Results showed significantly down-regulated expression of Bmal1, Per1, Per2 and Wee1 and significantly up-regulated expression of Myc and Cyclin D1 (P < 0.0001) in CLL patients as compared to healthy controls. When expression of these genes was compared between shift-workers and non-shift-workers within the CLL group, the expression was found more aberrant in shift-workers as compared to non-shift-workers. However, this difference was found statistically significant for Myc and Cyclin D1 only (P < 0.05). Serum melatonin levels were found significantly low (P < 0.0001) in CLL subjects as compared to healthy controls whereas melatonin levels were found still lower in shift-workers as compared to non-shift-workers within CLL group (P < 0.01). Our results suggest that aberrant expression of circadian clock genes can lead to aberrant expression of their downstream targets that are

  7. Efficient retrovirus-mediated transfer of cell-cycle control genes to transformed cells.

    PubMed

    Strauss, B E; Costanzi-Strauss, E

    1999-07-01

    The use of gene therapy continues to be a promising, yet elusive, alternative for the treatment of cancer. The origins of cancer must be well understood so that the therapeutic gene can be chosen with the highest chance of successful tumor regression. The gene delivery system must be tailored for optimum transfer of the therapeutic gene to the target tissue. In order to accomplish this, we study models of G1 cell-cycle control in both normal and transformed cells in order to understand the reasons for uncontrolled cellular proliferation. We then use this information to choose the gene to be delivered to the cells. We have chosen to study p16, p21, p53 and pRb gene transfer using the pCL-retrovirus. Described here are some general concepts and specific results of our work that indicate continued hope for the development of genetically based cancer treatments.

  8. The feedback control cycle as regulator of past and future mineral supply

    NASA Astrophysics Data System (ADS)

    Wellmer, Friedrich-W.; Dalheimer, Manfred

    2012-10-01

    Mineral supply is controlled by a feedback mechanism. When there is a shortage of a commodity in a market economy, prices will rise, triggering this mechanism. The expectation of high financial returns will encourage inventiveness and creativity in the quest for new solutions. On the supply side, for primary resources, the appropriate response is to cut losses in the mining process, to lower the cut-off grade, to improve recoveries in the beneficiation and smelting processes, to expand existing production facilities, and to discover and bring into production new deposits. For secondary resources, the key to increasing the supply lies in improving recycling rates by better technology, reprocessing lower-grade scrap which becomes economic because of increased prices, and reducing downgrading to optimize the usefulness of secondary materials. On the demand side, implementation of new and more efficient processes, development of substitution technologies, material savings, and the invention of entirely new technologies that fulfill the same function without the need of using the scarce and suddenly more expensive material are effective reactions to a price rise. The effectiveness of this self-regulating mechanism can be shown by examples of historical price peaks of metals, such as Mo, Co, and Ta, and the current rare earth elements peak. Concerning supply from secondary resources, a model is developed in order to determine how far the supply from this resource domain can be achieved and how the recycling rate is influenced by growth rate and lifetime. The feedback control cycle of mineral supply is influenced on the demand side by ever shorter life cycles, by products getting more complex with ever more elements involved in their production, and by an increase in element dispersion. All these factors have an immediate effect on the feasibility of sourcing raw materials from the technosphere. The supply side of primary materials is influenced by increasing lead times

  9. Technological and life cycle assessment of organics processing odour control technologies.

    PubMed

    Bindra, Navin; Dubey, Brajesh; Dutta, Animesh

    2015-09-15

    As more municipalities and communities across developed world look towards implementing organic waste management programmes or upgrading existing ones, composting facilities are emerging as a popular choice. However, odour from these facilities continues to be one of the most important concerns in terms of cost & effective mitigation. This paper provides a technological and life cycle assessment of some of the different odour control technologies and treatment methods that can be implemented in organics processing facilities. The technological assessment compared biofilters, packed tower wet scrubbers, fine mist wet scrubbers, activated carbon adsorption, thermal oxidization, oxidization chemicals and masking agents. The technologies/treatment methods were evaluated and compared based on a variety of operational, usage and cost parameters. Based on the technological assessment it was found that, biofilters and packed bed wet scrubbers are the most applicable odour control technologies for use in organics processing faculties. A life cycle assessment was then done to compare the environmental impacts of the packed-bed wet scrubber system, organic (wood-chip media) bio-filter and inorganic (synthetic media) bio-filter systems. Twelve impact categories were assessed; cumulative energy demand (CED), climate change, human toxicity, photochemical oxidant formation, metal depletion, fossil depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial eco-toxicity, freshwater eco-toxicity and marine eco-toxicity. The results showed that for all impact categories the synthetic media biofilter had the highest environmental impact, followed by the wood chip media bio-filter system. The packed-bed system had the lowest environmental impact for all categories.

  10. Wildfire, thermokarst and vegetation change: integrating diverse controls over carbon cycling in arctic and boreal ecosystems

    NASA Astrophysics Data System (ADS)

    Mack, M. C.; Alexander, H. D.; DeMarco, J.; Melvin, A.

    2012-12-01

    Climate is warming more rapidly in the tundra and forests of high northern latitudes than any other place on earth. Large, globally-important stocks of carbon (C) reside in these ecosystems. Characterized by cold, moist climate and frozen soils, these ecosystems have historically acted as a net sink for atmospheric C: they remove more C from the atmosphere on an annual basis than they release, resulting in the accumulation of large stocks in soils and plants. With warming climate comes the potential for fundamental changes in ecological controls over C cycling. Plant growth is limited by both low temperature and the slow regeneration of nutrients such as nitrogen (N). If warming stimulates plant growth by alleviating these limitations, than C uptake may increase. Indeed, satellite indices of greening as well as observations of shrub expansion and northern migration of the arctic treeline point towards increased plant productivity concurrent with climate warming. But as soils warm, microbial decomposition and release of C to the atmosphere, as well as disturbances such as wildfire or thermal erosion (thermokarst), are likely to increase, and it is unclear whether increased C loss may balance or even outweigh increased production, at least on the time-scale of decades to centuries. Understanding the net outcome of these two processes is important because it determines the sign of the feedback between the arctic/boreal C cycle and climate. A positive feedback, where warming increases C losses more than uptake, would amplify anthropogenic changes in climate, accelerating warming and destabilizing feedbacks between ecosystems and the atmosphere. A negative feedback, by contrast, where warming increases C uptake more than losses, would dampen the anthropogenic signal and stabilize climate. This presentation will focus on three general areas of ecological control over net ecosystem C balance in arctic and boreal ecosystems: nutrient availability, changing disturbance

  11. Minimal Models for Cell-Cycle Control Based on Competitive Inhibition and Multisite Phosphorylations of Cdk Substrates

    PubMed Central

    Gérard, Claude; Tyson, John J.; Novák, Béla

    2013-01-01

    The eukaryotic cell cycle is characterized by alternating oscillations in the activities of cyclin-dependent kinase (Cdk) and the anaphase-promoting complex (APC). Successful completion of the cell cycle is dependent on the precise, temporally ordered appearance of these activities. A modest level of Cdk activity is sufficient to initiate DNA replication, but mitosis and APC activation require an elevated Cdk activity. In present-day eukaryotes, this temporal order is provided by a complex network of regulatory proteins that control both Cdk and APC activities via sharp thresholds, bistability, and time delays. Using simple computational models, we show here that these dynamical features of cell-cycle organization could emerge in a control system driven by a single Cdk/cyclin complex and APC wired in a negative-feedback loop. We show that ordered phosphorylation of cellular proteins could be explained by multisite phosphorylation/dephosphorylation and competition of substrates for interconverting kinase (Cdk) and phosphatase. In addition, the competition of APC substrates for ubiquitylation can create and maintain sustained oscillations in cyclin levels. We propose a sequence of models that gets closer and closer to a realistic model of cell-cycle control in yeast. Since these models lack the elaborate control mechanisms characteristic of modern eukaryotes, they suggest that bistability and time delay may have characterized eukaryotic cell divisions before the current cell-cycle control network evolved in all its complexity. PMID:23528096

  12. Length of Menstrual Cycle and Risk of Endometriosis: A Meta-Analysis of 11 Case-Control Studies.

    PubMed

    Wei, Ming; Cheng, Yanfei; Bu, Huaien; Zhao, Ye; Zhao, Wenli

    2016-03-01

    Endometriosis is a complex disease that affects a large number of women worldwide and may cause pain and infertility. To systematically review published studies evaluating the relationship between menstrual cycle length and risk of endometriosis. We searched the Cochrane Library, PubMed, Web of Science, and EMBASE in databases in July 2014 using the keywords "case-control studies," "epidemiologic determinants," "risk factors," "menstrual cycle," "menstrual length," "menstrual character," and "endometriosis." We included case-control studies published in English that investigated cases of surgically confirmed endometriosis and examined the relationship between endometriosis risk and menstrual cycle. Eleven articles that met the inclusion criteria included data of 3392 women with endometriosis and 5006 controls. Fixed-effects and random-effects models were used for the evaluation. For the association of risk of endometriosis and menstrual cycle length shorter than or equal to 27 days (SEQ27) or length longer than or equal to 29 days (LEQ29), the odds ratio was 1.22 (95% confidence interval [CI]: 1.05-1.43) and 0.68 (95% CI: 0.48-0.96), respectively. In conclusion, this meta-analysis suggests that menstrual cycle length SEQ27 increase the risk of endometriosis and cycle length LEQ29 decrease the risk.

  13. Dilution of the cell cycle inhibitor Whi5 controls budding-yeast cell size.

    PubMed

    Schmoller, Kurt M; Turner, J J; Kõivomägi, M; Skotheim, Jan M

    2015-10-01

    Cell size fundamentally affects all biosynthetic processes by determining the scale of organelles and influencing surface transport. Although extensive studies have identified many mutations affecting cell size, the molecular mechanisms underlying size control have remained elusive. In the budding yeast Saccharomyces cerevisiae, size control occurs in G1 phase before Start, the point of irreversible commitment to cell division. It was previously thought that activity of the G1 cyclin Cln3 increased with cell size to trigger Start by initiating the inhibition of the transcriptional inhibitor Whi5 (refs 6-8). Here we show that although Cln3 concentration does modulate the rate at which cells pass Start, its synthesis increases in proportion to cell size so that its total concentration is nearly constant during pre-Start G1. Rather than increasing Cln3 activity, we identify decreasing Whi5 activity--due to the dilution of Whi5 by cell growth--as a molecular mechanism through which cell size controls proliferation. Whi5 is synthesized in S/G2/M phases of the cell cycle in a largely size-independent manner. This results in smaller daughter cells being born with higher Whi5 concentrations that extend their pre-Start G1 phase. Thus, at its most fundamental level, size control in budding yeast results from the differential scaling of Cln3 and Whi5 synthesis rates with cell size. More generally, our work shows that differential size-dependency of protein synthesis can provide an elegant mechanism to coordinate cellular functions with growth. PMID:26390151

  14. Effects of maximal oxygen uptake test and prolonged cycle ergometer exercise on the quiet standing control.

    PubMed

    Mello, Roger Gomes Tavares; de Oliveira, Liliam Fernandes; Nadal, Jurandir

    2010-06-01

    This work aims at testing the influence of peripheral and central fatigue, after maximal oxygen uptake test (Test1) and prolonged (Test2) cycle ergometer exercises, respectively, on sway density curve (SDC) parameters of postural control. Sixteen healthy male subjects were submitted to stabilometric tests, before and after the exercises. The Test1 was started at 12.5W, with 12.5W/min increments and 50rpm cadence until exhaustion. From the respiratory gas exchange signals, the first ventilatory threshold was obtained by the v-slope method. After a minimum of 72h, the subjects performed the Test2 for 60min, at a power output corresponding to 70% of such threshold. Before and just after these exercises, a set of 10 stabilometric trials of 50s was performed, alternating the eyes open and closed conditions, intercalated by a 10s resting period. The resulting signals were used to obtain the SDC. The Test1 caused decrease of the mean of peaks duration in SDC (p<0.05), decreasing the stability level, with small changes in the rates of central nervous system (CNS) and muscular torque controls. Conversely, Test2 increased the mean of time intervals between peaks in SDC (p<0.05), thus decreasing the CNS commands rate with minor changes in the stability level. Visual privation had a greater effect on body sway than these exercises, which were applied to muscles that are not the main actuators in body sway control. Concluding, this study allowed discriminating the effects of exercise intensities on body sway control.

  15. Bioelectric controls of cell proliferation: ion channels, membrane voltage and the cell cycle.

    PubMed

    Blackiston, Douglas J; McLaughlin, Kelly A; Levin, Michael

    2009-11-01

    All cells possess long-term, steady-state voltage gradients across the plasma membrane. These transmembrane potentials arise from the combined activity of numerous ion channels, pumps and gap junction complexes. Increasing data from molecular physiology now reveal that the role of changes in membrane voltage controls, and is in turn controlled by, progression through the cell cycle. We review recent functional data on the regulation of mitosis by bioelectric signals, and the function of membrane voltage and specific potassium, sodium and chloride ion channels in the proliferation of embryonic, somatic and neoplastic cells. Its unique properties place this powerful, well-conserved, but still poorly-understood signaling system at the center of the coordinated cellular interactions required for complex pattern formation. Moreover, disregulation of ion channel expression and function is increasingly observed to be not only a useful marker but likely a functional element in oncogenesis. New advances in genomics and the development of in vivo biophysical techniques suggest exciting opportunities for molecular medicine, bioengineering and regenerative approaches to human health. PMID:19823012

  16. Processes controlling the annual cycle of Arctic aerosol number and size distributions

    NASA Astrophysics Data System (ADS)

    Croft, Betty; Martin, Randall V.; Leaitch, W. Richard; Tunved, Peter; Breider, Thomas J.; D'Andrea, Stephen D.; Pierce, Jeffrey R.

    2016-03-01

    Measurements at high-Arctic sites (Alert, Nunavut, and Mt. Zeppelin, Svalbard) during the years 2011 to 2013 show a strong and similar annual cycle in aerosol number and size distributions. Each year at both sites, the number of aerosols with diameters larger than 20 nm exhibits a minimum in October and two maxima, one in spring associated with a dominant accumulation mode (particles 100 to 500 nm in diameter) and a second in summer associated with a dominant Aitken mode (particles 20 to 100 nm in diameter). Seasonal-mean aerosol effective diameter from measurements ranges from about 180 in summer to 260 nm in winter. This study interprets these annual cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. Important roles are documented for several processes (new-particle formation, coagulation scavenging in clouds, scavenging by precipitation, and transport) in controlling the annual cycle in Arctic aerosol number and size. Our simulations suggest that coagulation scavenging of interstitial aerosols in clouds by aerosols that have activated to form cloud droplets strongly limits the total number of particles with diameters less than 200 nm throughout the year. We find that the minimum in total particle number in October can be explained by diminishing new-particle formation within the Arctic, limited transport of pollution from lower latitudes, and efficient wet removal. Our simulations indicate that the summertime-dominant Aitken mode is associated with efficient wet removal of accumulation-mode aerosols, which limits the condensation sink for condensable vapours. This in turn promotes new-particle formation and growth. The dominant accumulation mode during spring is associated with build up of transported pollution from outside the Arctic coupled with less-efficient wet-removal processes at colder temperatures. We recommend further attention to the key processes of new-particle formation, interstitial coagulation, and wet removal and their delicate

  17. Pericyte contractility controls endothelial cell cycle progression and sprouting: insights into angiogenic switch mechanics.

    PubMed

    Durham, Jennifer T; Surks, Howard K; Dulmovits, Brian M; Herman, Ira M

    2014-11-01

    Microvascular stability and regulation of capillary tonus are regulated by pericytes and their interactions with endothelial cells (EC). While the RhoA/Rho kinase (ROCK) pathway has been implicated in modulation of pericyte contractility, in part via regulation of the myosin light chain phosphatase (MLCP), the mechanisms linking Rho GTPase activity with actomyosin-based contraction and the cytoskeleton are equivocal. Recently, the myosin phosphatase-RhoA-interacting protein (MRIP) was shown to mediate the RhoA/ROCK-directed MLCP inactivation in vascular smooth muscle. Here we report that MRIP directly interacts with the β-actin-specific capping protein βcap73. Furthermore, manipulation of MRIP expression influences pericyte contractility, with MRIP silencing inducing cytoskeletal remodeling and cellular hypertrophy. MRIP knockdown induces a repositioning of βcap73 from the leading edge to stress fibers; thus MRIP-silenced pericytes increase F-actin-driven cell spreading twofold. These hypertrophied and cytoskeleton-enriched pericytes demonstrate a 2.2-fold increase in contractility upon MRIP knockdown when cells are plated on a deformable substrate. In turn, silencing pericyte MRIP significantly affects EC cycle progression and angiogenic activation. When MRIP-silenced pericytes are cocultured with capillary EC, there is a 2.0-fold increase in EC cycle entry. Furthermore, in three-dimensional models of injury and repair, silencing pericyte MRIP results in a 1.6-fold elevation of total tube area due to EC network formation and increased angiogenic sprouting. The pivotal role of MRIP expression in governing pericyte contractile phenotype and endothelial growth should lend important new insights into how chemomechanical signaling pathways control the "angiogenic switch" and pathological angiogenic induction.

  18. Protein farnesyltransferase in plants: molecular characterization and involvement in cell cycle control.

    PubMed Central

    Qian, D; Zhou, D; Ju, R; Cramer, C L; Yang, Z

    1996-01-01

    Farnesylation is required for membrane targeting, protein-protein interactions, and the biological activity of key regulatory proteins, such as Ras small GTPases and protein kinases in a wide range of eukaryotes. In this report, we describe the molecular identification of a plant protein farnesyltransferase (FTase) and evidence for its role in the control of the cell cycle in plants. A pea gene encoding a homolog of the FTase beta subunit was previously cloned using a polymerase chain reaction-based strategy. A similar approach was used to clone a pea gene encoding a homolog of the FTase alpha subunit. The biochemical function of the pea FTase homologs was demonstrated by the reconstitution of FTase enzyme activity using FTase fusion proteins coexpressed in Escherichia coll. RNA gel blot analyses showed that levels of FTase mRNAs are generally higher in tissues, such as those of nodules, that are active in cell division. The relationship of FTase to cell division was further analyzed during the growth of suspension-cultured tobacco BY-2 cells. A biphasic fluctuation of FTase enzyme activity preceded corresponding changes in mitotic activity at the early log phase of cell growth. Moreover, manumycin, a specific inhibitor of FTase, was effective in inhibiting mitosis and growth in these cells. Using synchronized BY-2 cells, manumycin completely blocked mitosis when added at the early S phase but not when added at the G2 phase. These data suggest that FTase is required for the plant cell cycle, perhaps by modulating the progression through the S phase and the transition from G1 to the S phase. PMID:8989889

  19. The potential for control of carbon dioxide emissions from integrated gasification/combined-cycle systems

    SciTech Connect

    Livengood, C.D.; Doctor, R.D.; Molburg, J.C.; Thimmapuram, P.; Berry, G.F.

    1994-06-01

    Initiatives to limit carbon dioxide (CO{sub 2}) emissions have drawn considerable interest to integrated gasification/combined-cycle (IGCC) power generation, a process that reduces CO{sub 2} production through efficient fuel used is amenable to CO{sub 2} capture. This paper presents a comparison of energy systems that encompass fuel supply, an IGCC system, CO{sub 2} recovery using commercial technologies, CO{sub 2} transport by pipeline, and land-based sequestering in geological reservoirs. The intent is to evaluate the energy-efficiency impacts of controlling CO{sub 2} in such systems and to provide the CO{sub 2} budget, or an to equivalent CO{sub 2}`` budget, associated with each of the individual energy-cycle steps. The value used for the ``equivalent CO{sub 2}`` budget is 1 kg/kWh CO{sub 2}. The base case for the comparison is a 457-MW IGCC system that uses an air-blown Kellogg-Rust-Westinghouse (KRW) agglomerating fluidized-bed gasifier, Illinois No. 6 bituminous coal, and in-bed sulfur removal. Mining, preparation, and transportation of the coal and limestone result in a net system electric power production of 454 MW with a 0.835 kg/kwh CO{sub 2} release rate. For comparison, the gasifier output is taken through a water-gas shift to convert CO to CO{sub 2} and then processed in a glycol-based absorber unit to recover CO{sub 2} Prior to the combustion turbine. A 500-km pipeline then transports the CO{sub 2} for geological sequestering. The net electric power production for the system with CO{sub 2} recovery is 381 MW with a 0.156 kg/kwh CO{sub 2} release rate.

  20. Lyapunov-based control of limit cycle oscillations in uncertain aircraft systems

    NASA Astrophysics Data System (ADS)

    Bialy, Brendan

    Store-induced limit cycle oscillations (LCO) affect several fighter aircraft and is expected to remain an issue for next generation fighters. LCO arises from the interaction of aerodynamic and structural forces, however the primary contributor to the phenomenon is still unclear. The practical concerns regarding this phenomenon include whether or not ordnance can be safely released and the ability of the aircrew to perform mission-related tasks while in an LCO condition. The focus of this dissertation is the development of control strategies to suppress LCO in aircraft systems. The first contribution of this work (Chapter 2) is the development of a controller consisting of a continuous Robust Integral of the Sign of the Error (RISE) feedback term with a neural network (NN) feedforward term to suppress LCO behavior in an uncertain airfoil system. The second contribution of this work (Chapter 3) is the extension of the development in Chapter 2 to include actuator saturation. Suppression of LCO behavior is achieved through the implementation of an auxiliary error system that features hyperbolic functions and a saturated RISE feedback control structure. Due to the lack of clarity regarding the driving mechanism behind LCO, common practice in literature and in Chapters 2 and 3 is to replicate the symptoms of LCO by including nonlinearities in the wing structure, typically a nonlinear torsional stiffness. To improve the accuracy of the system model a partial differential equation (PDE) model of a flexible wing is derived (see Appendix F) using Hamilton's principle. Chapters 4 and 5 are focused on developing boundary control strategies for regulating the bending and twisting deformations of the derived model. The contribution of Chapter 4 is the construction of a backstepping-based boundary control strategy for a linear PDE model of an aircraft wing. The backstepping-based strategy transforms the original system to a exponentially stable system. A Lyapunov-based stability

  1. How do changes in dissolved oxygen concentration influence microbially-controlled phosphorus cycling in stream biofilms?

    NASA Astrophysics Data System (ADS)

    Saia, S. M.; Locke, N. A.; Regan, J. M.; Carrick, H. J.; Buda, A. R.; Walter, M. T.

    2014-12-01

    Advances in molecular microbiology techniques (e.g. epi-fluorescent microscopy and PCR) are making it easier to study the influence of specific microorganisms on nutrient transport. Polyphosphate accumulating organisms (PAOs) are commonly used in wastewater treatment plants to remove excess phosphorus (P) from effluent water. PAOs have also been identified in natural settings but their ecological function is not well known. In this study, we tested the hypothesis that PAOs in natural environments would release and accumulate P during anaerobic and aerobic conditions, respectively. We placed stream biofilms in sealed, covered tubs and subjected them to alternating air (aerobic conditions) and N2 gas (anaerobic condition) bubbling for 12 hours each. Four treatments investigated the influence of changing dissolved oxygen on micribially-controlled P cycling: (1) biofilms bubbled continuously with air, (2) biofilms bubbled alternatively with air and N2, (3) biocide treated biofilms bubbled continuously with air, and (4) biocide treated biofilms bubbled alternatively with air and N2. Treatments 3 and 4 serve as abiotic controls to treatments 1 and 2. We analyzed samples every 12 hours for soluble reactive P (SRP), temperature, dissolved oxygen, and pH. We also used fluorescent microscopy (i.e. DAPI staining) and PCR to verify the presence of PAOs in the stream biofilms. SRP results over the course of the experiment support our hypothesis that anaerobic and aerobic stream conditions may impact PAO mediated P release and uptake, respectively in natural environments. The results of these experiments draw attention to the importance of microbiological controls on P mobility in freshwater ecosystems.

  2. Control of leg-powered paraplegic cycling using stimulation of the lumbo-sacral anterior spinal nerve roots.

    PubMed

    Perkins, Tim A; de N Donaldson, Nick; Hatcher, Neil A C; Swain, Ian D; Wood, Duncan E

    2002-09-01

    We investigated leg-powered cycling in a recumbent tricycle for a paraplegic using functional electrical stimulation (FES) with the lumbo-sacral anterior root stimulator implant (LARSI). A female complete T9 paraplegic had a stimulator for the anterior L2 to S2 spinal roots (bilaterally) implanted in 1994. She was provided with equipment for daily FES cycling exercise at home. The cycling controller applies a pattern of stimulation in each of 16 crank angle phases. A 7-bit shaft encoder measures the crank angle with adequate precision. Each pattern was originally chosen to give the greatest propulsive force in that position when there was no motion. However, dynamically, some reduction in co-contraction is needed; also the patterns are applied with a preset advance time. Maximal power is obtained with an advance of 250 ms, which compensates for muscle response delay and accommodates changes in cadence (from about 25 to 85 rpm). With this system, she has cycled 1.2 km at a time on gently undulating road. We found that spinal root stimulation gives sufficient control over the muscles in the legs to produce a fluid cycling gait. We propose that root stimulation for leg cycling exercise may be a practicable and valuable function for paraplegics following spinal cord injury.

  3. Control of leg-powered paraplegic cycling using stimulation of the lumbo-sacral anterior spinal nerve roots.

    PubMed

    Perkins, Tim A; de N Donaldson, Nick; Hatcher, Neil A C; Swain, Ian D; Wood, Duncan E

    2002-09-01

    We investigated leg-powered cycling in a recumbent tricycle for a paraplegic using functional electrical stimulation (FES) with the lumbo-sacral anterior root stimulator implant (LARSI). A female complete T9 paraplegic had a stimulator for the anterior L2 to S2 spinal roots (bilaterally) implanted in 1994. She was provided with equipment for daily FES cycling exercise at home. The cycling controller applies a pattern of stimulation in each of 16 crank angle phases. A 7-bit shaft encoder measures the crank angle with adequate precision. Each pattern was originally chosen to give the greatest propulsive force in that position when there was no motion. However, dynamically, some reduction in co-contraction is needed; also the patterns are applied with a preset advance time. Maximal power is obtained with an advance of 250 ms, which compensates for muscle response delay and accommodates changes in cadence (from about 25 to 85 rpm). With this system, she has cycled 1.2 km at a time on gently undulating road. We found that spinal root stimulation gives sufficient control over the muscles in the legs to produce a fluid cycling gait. We propose that root stimulation for leg cycling exercise may be a practicable and valuable function for paraplegics following spinal cord injury. PMID:12503780

  4. Design of a symmetry controller for cycling induced by electrical stimulation: preliminary results on post-acute stroke patients.

    PubMed

    Ambrosini, Emilia; Ferrante, Simona; Schauer, Thomas; Ferrigno, Giancarlo; Molteni, Franco; Pedrocchi, Alessandra

    2010-08-01

    This study deals with the design of a controller for cycling induced by functional electrical stimulation. The controller will be exploitable in the rehabilitation of hemiparetic patients who need to recover motor symmetry. It uses the pulse width as the control variable in the stimulation of the two legs in order to nullify the unbalance between the torques produced at the two crank arms. It was validated by means of isokinetic trials performed both by healthy subjects and stroke patients. The results showed that the controller was able to reach, and then maintain, a symmetrical pedaling. In the future, the controller will be validated on a larger number of stroke patients.

  5. Design of a symmetry controller for cycling induced by electrical stimulation: preliminary results on post-acute stroke patients.

    PubMed

    Ambrosini, Emilia; Ferrante, Simona; Schauer, Thomas; Ferrigno, Giancarlo; Molteni, Franco; Pedrocchi, Alessandra

    2010-08-01

    This study deals with the design of a controller for cycling induced by functional electrical stimulation. The controller will be exploitable in the rehabilitation of hemiparetic patients who need to recover motor symmetry. It uses the pulse width as the control variable in the stimulation of the two legs in order to nullify the unbalance between the torques produced at the two crank arms. It was validated by means of isokinetic trials performed both by healthy subjects and stroke patients. The results showed that the controller was able to reach, and then maintain, a symmetrical pedaling. In the future, the controller will be validated on a larger number of stroke patients. PMID:20528850

  6. The CHR promoter element controls cell cycle-dependent gene transcription and binds the DREAM and MMB complexes

    PubMed Central

    Müller, Gerd A.; Quaas, Marianne; Schümann, Michael; Krause, Eberhard; Padi, Megha; Fischer, Martin; Litovchick, Larisa; DeCaprio, James A.; Engeland, Kurt

    2012-01-01

    Cell cycle-dependent gene expression is often controlled on the transcriptional level. Genes like cyclin B, CDC2 and CDC25C are regulated by cell cycle-dependent element (CDE) and cell cycle genes homology region (CHR) promoter elements mainly through repression in G0/G1. It had been suggested that E2F4 binding to CDE sites is central to transcriptional regulation. However, some promoters are only controlled by a CHR. We identify the DREAM complex binding to the CHR of mouse and human cyclin B2 promoters in G0. Association of DREAM and cell cycle-dependent regulation is abrogated when the CHR is mutated. Although E2f4 is part of the complex, a CDE is not essential but can enhance binding of DREAM. We show that the CHR element is not only necessary for repression of gene transcription in G0/G1, but also for activation in S, G2 and M phases. In proliferating cells, the B-myb-containing MMB complex binds the CHR of both promoters independently of the CDE. Bioinformatic analyses identify many genes which contain conserved CHR elements in promoters binding the DREAM complex. With Ube2c as an example from that screen, we show that inverse CHR sites are functional promoter elements that can bind DREAM and MMB. Our findings indicate that the CHR is central to DREAM/MMB-dependent transcriptional control during the cell cycle. PMID:22064854

  7. Inhibition of nitrogenase by oxygen in marine cyanobacteria controls the global nitrogen and oxygen cycles

    NASA Astrophysics Data System (ADS)

    Berman-Frank, I.; Chen, Y.-B.; Gerchman, Y.; Dismukes, G. C.; Falkowski, P. G.

    2005-03-01

    Cyanobacterial N2-fixation supplies the vast majority of biologically accessible inorganic nitrogen to nutrient-poor aquatic ecosystems. The process, catalyzed by the heterodimeric protein complex, nitrogenase, is thought to predate that of oxygenic photosynthesis. Remarkably, while the enzyme plays such a critical role in Earth's biogeochemical cycles, the activity of nitrogenase in cyanobacteria is markedly inhibited in vivo at a post-translational level by the concentration of O2 in the contemporary atmosphere leading to metabolic and biogeochemical inefficiency in N2 fixation. We illustrate this crippling effect with data from Trichodesmium spp. an important contributor of "new nitrogen" to the world's subtropical and tropical oceans. The enzymatic inefficiency of nitrogenase imposes a major elemental taxation on diazotrophic cyanobacteria both in the costs of protein synthesis and for scarce trace elements, such as iron. This restriction has, in turn, led to a global limitation of fixed nitrogen in the contemporary oceans and provides a strong biological control on the upper bound of oxygen concentration in Earth's atmosphere.

  8. Life-cycle assessment of selected management options for air pollution control residues from waste incineration.

    PubMed

    Fruergaard, Thilde; Hyks, Jiri; Astrup, Thomas

    2010-09-15

    Based on available technology and emission data seven selected management options for air-pollution-control (APC) residues from waste incineration were evaluated by life-cycle assessment (LCA) using the EASEWASTE model. Scenarios were evaluated with respect to both non-toxicity impact categories (e.g. global warming) and toxicity related impact categories (e.g. ecotoxicity and human toxicity). The assessment addressed treatment and final placement of 1 tonne of APC residue in seven scenarios: 1) direct landfilling without treatment (baseline), 2) backfilling in salt mines, 3) neutralization of waste acid, 4) filler material in asphalt, 5) Ferrox stabilization, 6) vitrification, and 7) melting with automobile shredder residues (ASR). The management scenarios were selected as examples of the wide range of different technologies available worldwide while at the same time using realistic technology data. Results from the LCA were discussed with respect to importance of: energy consumption/substitution, material substitution, leaching, air emissions, time horizon aspects for the assessment, and transportation distances. The LCA modeling showed that thermal processes were associated with the highest loads in the non-toxicity categories (energy consumption), while differences between the remaining alternatives were small and generally considered insignificant. In the toxicity categories, all treatment/utilization options were significantly better than direct landfilling without treatment (lower leaching), although the thermal processes had somewhat higher impacts than the others options (air emissions). Transportation distances did not affect the overall ranking of the management alternatives.

  9. Oocyte-specific differences in cell-cycle control create an innate susceptibility to meiotic errors.

    PubMed

    Nagaoka, So Iha; Hodges, Craig A; Albertini, David F; Hunt, Patricia Ann

    2011-04-26

    Segregation of homologs at the first meiotic division (MI) is facilitated by crossovers and by a physical constraint imposed on sister kinetochores that facilitates monopolar attachment to the MI spindle. Recombination failure or premature separation of homologs results in univalent chromosomes at MI, and univalents constrained to form monopolar attachments should be inherently unstable and trigger the spindle assembly checkpoint (SAC). Although univalents trigger cell-cycle arrest in the male, this is not the case in mammalian oocytes. Because the spindle assembly portion of the SAC appears to function normally, two hypotheses have been proposed to explain the lack of response to univalents: (1) reduced stringency of the oocyte SAC to aberrant chromosome behavior, and (2) the ability of univalents to satisfy the SAC by forming bipolar attachments. The present study of Mlh1 mutant mice demonstrates that metaphase alignment is not a prerequisite for anaphase onset and provides strong evidence that MI spindle stabilization and anaphase onset require stable bipolar attachment of a critical mass--but not all--of chromosomes. We postulate that subtle differences in SAC-mediated control make the human oocyte inherently error prone and contribute to the age-related increase in aneuploidy.

  10. Toward full life cycle control: Adding maintenance measurement to the SEL

    NASA Technical Reports Server (NTRS)

    Rombach, H. Dieter; Ulery, Bradford T.; Valett, Jon D.

    1992-01-01

    Organization-wide measurement of software products and processes is needed to establish full life cycle control over software products. The Software Engineering Laboratory (SEL)--a joint venture between NASA GSFC, the University of Maryland, and Computer Sciences Corporation--started measurement of software development more than 15 years ago. Recently, the measurement of maintenance was added to the scope of the SEL. In this article, the maintenance measurement program is presented as an addition to the already existing and well-established SEL development measurement program and evaluated in terms of its immediate benefits and long-term improvement potential. Immediate benefits of this program for the SEL include an increased understanding of the maintenance domain, the differences and commonalities between development and maintenance, and the cause-effect relationships between development and maintenance. Initial results from a sample maintenance study are presented to substantiate these benefits. The long-term potential of this program includes the use of maintenance baselines to better plan and manage future projects and to improve development and maintenance practices for future projects wherever warranted.

  11. Effect of Processing Route on Strain Controlled Low Cycle Fatigue Behavior of Polycrystalline NiAl

    NASA Technical Reports Server (NTRS)

    Rao, K. Bhanu Sankara; Lerch, B. A.; Noebe, R. D.

    1995-01-01

    The present investigation examines the effects of manufacturing process on the total axial strain controlled low cycle fatigue behavior of polycrystalline NiAl at 1000 K, a temperature above the monotonic Brittle-to-Ductile Transition Temperature (BDTT). The nickel aluminide samples were produced by three different processing routes: hot isostatic pressing of pre- alloyed powders, extrusion of prealloyed powders, and extrusion of vacuum induction melted ingots. The LCF behavior of the cast plus extruded material was also determined at room temperature (below the BD77) for comparison to the high temperature data. The cyclic stress response, cyclic stress-strain behavior, and strain-life relationships were influenced by the alloy preparation technique and the testing temperature. Detailed characterization of the LCF tested samples was conducted by optical and electron microscopy to determine the variations in fracture and deformation modes and to determine any microstructural changes that occurred during LCF testing. The dependence of LCF properties on processing route was rationalized on the basis of starting microstructure, brittle-to-ductile transition temperature, deformation induced changes in the basic microstructure, deformation substructure, and synergistic interaction between the damage modes.

  12. Cell cycle control (and more) by programmed −1 ribosomal frameshifting: implications for disease and therapeutics

    PubMed Central

    Belew, Ashton T; Dinman, Jonathan D

    2015-01-01

    Abstract Like most basic molecular mechanisms, programmed –1 ribosomal frameshifting (−1 PRF) was first identified in viruses. Early observations that global dysregulation of −1 PRF had deleterious effects on yeast cell growth suggested that −1 PRF may be used to control cellular gene expression, and the cell cycle in particular. Collection of sufficient numbers of viral −1 PRF signals coupled with advances in computer sciences enabled 2 complementary computational approaches to identify −1 PRF signals in free living organisms. The unexpected observation that almost all −1 PRF events on eukaryotic mRNAs direct ribosomes to premature termination codons engendered the hypothesis that −1 PRF signals post-transcriptionally regulate gene expression by functioning as mRNA destabilizing elements. Emerging research suggests that some human diseases are associated with global defects in −1 PRF. The recent discovery of −1 PRF signal-specific trans-acting regulators may provide insight into novel therapeutic strategies aimed at treating diseases caused by changes in gene expression patterns. PMID:25584829

  13. Control of continuous irradiation injury on potatoes with daily temperature cycling

    NASA Technical Reports Server (NTRS)

    Tibbitts, T. W.; Bennett, S. M.; Cao, W.

    1990-01-01

    Two controlled-environment experiments were conducted to determine the effects of temperature fluctuations under continuous irradiation on growth and tuberization of two potato (Solanum tuberosum L.) cultivars, Kennebec and Superior. These cultivars had exhibited chlorotic and stunted growth under continuous irradiation and constant temperatures. The plants were grown for 4 weeks in the first experiment and for 6 weeks in the second experiment. Each experiment was conducted under continuous irradiation of 400 micromoles per square meter per second of photosynthetic photon flux and included two temperature treatments: constant 18 degrees C and fluctuating 22 degrees C/14 degrees C on a 12-hour cycle. A common vapor pressure deficit of 0.62 kilopascal was maintained at all temperatures. Plants under constant 18 degrees C were stunted and had chlorotic and abscised leaves and essentially no tuber formation. Plants grown under the fluctuating temperature treatment developed normally, were developing tubers, and had a fivefold or greater total dry weight as compared with those under the constant temperature. These results suggest that a thermoperiod can allow normal plant growth and tuberization in potato cultivars that are unable to develop effectively under continuous irradiation.

  14. Including Life Cycle Assessment for decision-making in controlling wastewater nutrient removal systems.

    PubMed

    Corominas, Lluís; Larsen, Henrik F; Flores-Alsina, Xavier; Vanrolleghem, Peter A

    2013-10-15

    This paper focuses on the use of Life Cycle Assessment (LCA) to evaluate the performance of seventeen control strategies in wastewater treatment plants (WWTPs). It tackles the importance of using site-specific factors for nutrient enrichment when decision-makers have to select best operating strategies. Therefore, the LCA evaluation is repeated for three different scenarios depending on the limitation of nitrogen (N), phosphorus (P), or both, when evaluating the nutrient enrichment impact in water bodies. The LCA results indicate that for treated effluent discharged into N-deficient aquatic systems (e.g. open coastal areas) the most eco-friendly strategies differ from the ones dealing with discharging into P-deficient (e.g. lakes and rivers) and N&P-deficient systems (e.g. coastal zones). More particularly, the results suggest that strategies that promote increased nutrient removal and/or energy savings present an environmental benefit for N&P and P-deficient systems. This is not the case when addressing N-deficient systems for which the use of chemicals (even for improving N removal efficiencies) is not always beneficial for the environment. A sensitivity analysis on using weighting of the impact categories is conducted to assess how value choices (policy decisions) may affect the management of WWTPs. For the scenarios with only N-limitation, the LCA-based ranking of the control strategies is sensitive to the choice of weighting factors, whereas this is not the case for N&P or P-deficient aquatic systems.

  15. Temporal stability of the action-perception cycle for postural control in a moving visual environment.

    PubMed

    Dijkstra, T M; Schöner, G; Gielen, C C

    1994-01-01

    When standing human subjects are exposed to a moving visual environment, the induced postural sway forms a stable temporal relationship with the visual information. We have investigated this relationship experimentally with a new set-up in which a computer generates video images which correspond to the motion of a 3D environment. The suggested mean distance to a sinusoidally moving wall is varied and the temporal relationship to induced sway is analysed (1) in terms of the fluctuations of relative phase between visual and sway motion and (2) in terms of the relaxation time of relative phase as determined from the rate of recovery of the stable relative phase pattern following abrupt changes in the visual motion pattern. The two measures are found to converge to a well-defined temporal stability of the action-perception cycle. Furthermore, we show that this temporal stability is a sensitive measure of the strength of the action-perception coupling. It decreases as the distance of the visual scene from the observer increases. This fact and the increase of mean relative phase are consistent with predictions of a linear second-order system driven by the visual expansion rate. However, the amplitude of visual sway decreases little as visual distance increases, in contradiction to the predictions, and is suggestive of a process that actively generates sway. The visual expansion rate on the optic array is found to decrease strongly with visual distance. This leads to the conclusion that postural control in a moving visual environment cannot be understood simply in terms of minimization of retinal slip, and that dynamic coupling of vision into the postural control system must be taken into account. PMID:8187859

  16. Including Life Cycle Assessment for decision-making in controlling wastewater nutrient removal systems.

    PubMed

    Corominas, Lluís; Larsen, Henrik F; Flores-Alsina, Xavier; Vanrolleghem, Peter A

    2013-10-15

    This paper focuses on the use of Life Cycle Assessment (LCA) to evaluate the performance of seventeen control strategies in wastewater treatment plants (WWTPs). It tackles the importance of using site-specific factors for nutrient enrichment when decision-makers have to select best operating strategies. Therefore, the LCA evaluation is repeated for three different scenarios depending on the limitation of nitrogen (N), phosphorus (P), or both, when evaluating the nutrient enrichment impact in water bodies. The LCA results indicate that for treated effluent discharged into N-deficient aquatic systems (e.g. open coastal areas) the most eco-friendly strategies differ from the ones dealing with discharging into P-deficient (e.g. lakes and rivers) and N&P-deficient systems (e.g. coastal zones). More particularly, the results suggest that strategies that promote increased nutrient removal and/or energy savings present an environmental benefit for N&P and P-deficient systems. This is not the case when addressing N-deficient systems for which the use of chemicals (even for improving N removal efficiencies) is not always beneficial for the environment. A sensitivity analysis on using weighting of the impact categories is conducted to assess how value choices (policy decisions) may affect the management of WWTPs. For the scenarios with only N-limitation, the LCA-based ranking of the control strategies is sensitive to the choice of weighting factors, whereas this is not the case for N&P or P-deficient aquatic systems. PMID:23856224

  17. Controls on diurnal streamflow cycles in a high altitude catchment in the Swiss Alps

    NASA Astrophysics Data System (ADS)

    Mutzner, R.; Weijs, S. V.; Tarolli, P.; Calaf, M.; Oldroyd, H. J.; Parlange, M. B.

    2014-12-01

    The study of streamflow diurnal cycles is of primary importance to understand hydrological processes happening at various spatial scales. In high altitude alpine catchments, streamflow diurnal cycles are typically dominated by snow or icemelt. During a field campaign in the summer 2012 in a small catchment in the Swiss Alps (Val Ferret catchment, draining area of 20.4 km2, mean altitude of 2423 m above sea level (asl), ranging from 1773 m to 3206 m asl, glaciarized area: 2%), we observed streamflow diurnal cycles throughout the season in two monitored sub-basins of the watershed. To study in detail the diurnal cycles, we make use of a wireless network of meteorological stations, time-lapse photography, a fully equipped energy-balance station and water electrical conductivity monitored at the gauging stations. In the first sub-basin, we observed a transition from a snowmelt to an evapotranspiration induced diurnal streamflow cycle. In the second sub-basin, we observed a snowmelt/icemelt dominated diurnal cycle during the entire season due to the presence of a small glacier. Comparisons between icemelt and evapotranspiration cycles showed that the two processes were happening at the same times of day but with a different sign. The amplitude of the icemelt cycle decreased exponentially during the season and was larger than of the amplitude of the evapotranspiration cycle which was relatively constant during the season. A conceptual model was applied to estimate the effect of evapotranspiration on the diurnal streamflow cycle in the icemelt dominated sub-basin. The model makes use of the latent heat measured at the energy balance station, the streamflow loss due to evapotranspiration and the computation of active evapotranspiration areas. Our study suggests that evapotranspiration from the riparian area damps the icemelt-diurnal streamflow cycle resulting in a possible underestimation of glacier mass changes.

  18. The cycle of instability: stress release and fissure flow as controls on gully head retreat

    NASA Astrophysics Data System (ADS)

    Collison, A. J. C.

    2001-01-01

    Gully head and wall retreat has commonly been attributed to fluvial scour and head collapse as a result of soil saturation, sapping or piping. The empirical evidence to substantiate these conceptual models is sparse, however, and often contradictory. This paper explores the hydrological and mechanical controls on gully head and wall stability by modelling the hydrology, stability and elastic deformation of a marl gully complex in Granada Province, south-east Spain. The hydrological and slope-stability simulations show that saturated conditions can be reached only where preferential fissure flow channels water from tension cracks into the base of the gully head, and that vertical or subvertical heads will be stable unless saturation is achieved. Owing to the high unsaturated strengths of marl measured in this research, failure in unsaturated conditions is possible only where the gully head wall is significantly undercut. Head retreat thus requires the formation of either a tension crack or an undercut hollow. Finite-element stress analysis of eroding slopes reveals a build up of shear stress at the gully head base, and a second stress anomaly just upslope of the head wall. Although tension cracks on gully heads have often been attributed to slope unloading, this research provides strong evidence that the so called sapping hollow commonly found in the gully headwall base is also a function of stress release. Although further research is needed, it seems possible that pop out failures in river channels may be caused by the same process. The hydrological analysis shows that, once a tension crack has developed, throughflow velocity in the gully headwall will increase by an order of magnitude, promoting piping and enlargement of this weakened area. It is, therefore, possible to envisage a cycle of gully expansion in which erosion, channel incision or human action unloads the slope below a gully head, leading to stress patterns that account for the tension crack and a

  19. Satellite-based Dust Source Identification over North Africa: Diurnal Cycle, Meteorological Controls, and Interannual Variability

    NASA Astrophysics Data System (ADS)

    Schepanski, Kerstin; Tegen, Ina; Macke, Andreas

    2010-05-01

    Mineral dust aerosol emitted from arid and semi-arid areas impacts on the weather and climate system by affecting e.g. radiation fluxes and nutrient cycles. To estimate the effect of dust aerosol, detailed knowledge on the spatio-temporal distribution of active dust sources is necessary. For a better representation of dust-related processes in numerical models and climate change projections the knowledge on the natural variability of dust source activity has to be improved. As dust sources are mostly located over remote areas satellite observations are suitable for identifying active dust sources. The accuracy of dust source identification using such an indirect method is limited by the temporal resolution and the ambiguities of the retrieval. Here, a data set on the spatial (1°x1°) and temporal (3-hourly) distribution of dust source activations (DSA) over North Africa is compiled by analyzing 15-minute Meteosat Second Generation (MSG) infra-red (IR) dust index images since March 2006. The index is designed using radiances measured by the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) on-board MSG at 8.7 µm, 10.8 µm and 12.0 µm which are converted to brightness temperatures (BTs). To strengthen the dust signal, differences of BTs are used to compute RGB-composite images. This newly data set providing information on the diurnal cycle of dust emission has been used (1) to identify most active dust source areas, and (2) to investigate on the temporal distribution of DSAs. Over the Sahara Desert 65% of dust sources become active during 06-09 UTC pointing towards an important role of the break-down of the nocturnal low-level jet (LLJ) for dust mobilization besides other meteorological features like density currents, haboobs, and cyclones. Furthermore the role of the nocturnal LLJs for dust mobilization over the Sahara is investigated by weather observations and a regional modeling study. Four years of DSA observations indicate an interannual variability in

  20. [The sexual cycle in the bitch: recent insights and impact on therapy and reproduction control].

    PubMed

    Jöchle, W

    1987-01-01

    Present knowledge about the estrous cycle of the bitch has been reviewed from a morphological, endocrinological and clinical point of view. This cycle is truly biphasic, characterized by its slow motion. It includes pregnancy or pseudopregnancy, and lactation. Corpus luteum function and regression as well as endometrial recovery, following endometrial desquamation at about day 100 of the cycle, are finalized at about days 140 to 150. Soon thereafter, subclinical preparations for the next proestrus can be recognized. Prolactin seems to play an important role as a luteotrophic agent, beginning at about day 30 to 35 of the cycle. Inhibition of prolactin secretion can be used to induce abortion, or to inhibit lactation and to shorten the cycle, or to treat clinical anestrus. Late metestrus and subclinical proestrus, i.e. days 120 to 170 of the cycle, is the most suitable period of the cycle to initiate suppression of the cycle, i.e. prevention of the next estrus, by using progestins with the least tendency for side effects.

  1. Autotrophic and Heterotrophic Controls over Winter Soil Carbon Cycling in a Subalpine Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Monson, R. K.; Scott-Denton, L. E.; Lipson, D. A.; Weintrub, M. N.; Rosenstiel, T. N.; Schmidt, S. K.; Williams, M. W.; Burns, S. P.; Delany, A. E.; Turnipseed, A. A.

    2005-12-01

    Studies were conducted at the Niwot Ridge Ameriflux site to understand wintertime soil carbon cycling and its control over ecosystem respiration. Wintertime respiration in this ecosystem results in the loss of 60-90% of the carbon assimilated the previous growing season. Thus, an understanding of the controls over winter carbon cycling is required to understand controls over the annual carbon budget. Trees were girdled to prevent the transport of photosynthates to the rhizosphere. In plots with non-girdled trees a large mid-winter pulse of sucrose was observed to enter the soil. In plots with girdled trees, no sucrose pulse was observed. Trees of this ecosystem are not photosynthetically active during the winter, leading us to conclude that the sucrose pulse is due to the death of fine roots that had accumulated sucrose the previous autumn. The sucrose pulse is potentially utilized by a novel winter community of microbes. Using DNA fingerprinting we discovered that the dominant isolates from the winter soils were from Jathinobacter, whereas the summer isolates were from Burkholderia. The winter community was capable of high rates of respiration and exponential growth at low temperatures, whereas the summer community was not. Our winter observations also indicated high activity of N-acetyl-C-glucosaminidase, one of the principal enzymes involved in chitin degradation. The presence of such high chitinase activities implicates decomposing fungal biomass as a principle source of CO2 beneath the snow pack. Using a novel in situ, beneath-snow CO2 measurement system, we observed unprecedented Q10 values for winter respiration, being 98 and 8.44 x 104 for the soil next to tree boles or within the open spaces between trees, respectively. These high Q10 values are likely the result of fractional changes in the availability of liquid water below 0°C and responses of microbial biomass to changes in the liquid water fraction. Using six-years of eddy covariance data, we showed

  2. The circadian molecular clock regulates adult hippocampal neurogenesis by controlling the timing of cell-cycle entry and exit.

    PubMed

    Bouchard-Cannon, Pascale; Mendoza-Viveros, Lucia; Yuen, Andrew; Kærn, Mads; Cheng, Hai-Ying M

    2013-11-27

    The subgranular zone (SGZ) of the adult hippocampus contains a pool of quiescent neural progenitor cells (QNPs) that are capable of entering the cell cycle and producing newborn neurons. The mechanisms that control the timing and extent of adult neurogenesis are not well understood. Here, we show that QNPs of the adult SGZ express molecular-clock components and proliferate in a rhythmic fashion. The clock proteins PERIOD2 and BMAL1 are critical for proper control of neurogenesis. The absence of PERIOD2 abolishes the gating of cell-cycle entrance of QNPs, whereas genetic ablation of bmal1 results in constitutively high levels of proliferation and delayed cell-cycle exit. We use mathematical model simulations to show that these observations may arise from clock-driven expression of a cell-cycle inhibitor that targets the cyclin D/Cdk4-6 complex. Our findings may have broad implications for the circadian clock in timing cell-cycle events of other stem cell populations throughout the body.

  3. G1 phase regulation, area-specific cell cycle control, and cytoarchitectonics in the primate cortex

    PubMed Central

    Lukaszewicz, Agnès; Savatier, Pierre; Cortay, Véronique; Giroud, Pascale; Huissoud, Cyril; Berland, Michel; Kennedy, Henry; Dehay, Colette

    2005-01-01

    We have investigated the cell-cycle related mechanisms that lead to the emergence of the primate areas 17 and 18. These areas are characterized by striking differences in cytoarchitectonics and neuron number. We show in vivo that (i) area 17 precursors of supragranular neurons exhibit a shorter cell-cycle duration, a reduced G1 phase and a higher rate of cell-cycle re-entry than area 18 precursors (ii) area-specific levels of expression of Cyclin E (high in area 17, low in area 18) and p27Kip1 (low in area 17, high in area 18) (iii) Ex vivo up and down modulation of Cyclin E and p27Kip1 show that both regulators influence cell-cycle kinetics by modifying rates of cell-cycle progression and cell-cycle re-entry (iv) Modeling the areal differences in cell-cycle parameters suggests that they contribute to areal differences in numbers of precursors and neuron production. PMID:16055060

  4. Results of chopper-controlled discharge life cycling studies on lead acid batteries

    NASA Technical Reports Server (NTRS)

    Ewashinka, J. G.; Sidik, S. M.

    1982-01-01

    A group of 108 state of the art nominally 6 volt lead acid batteries were tested in a program of one charge/discharge cycle per day for over two years or to ultimate battery failure. The primary objective was to determine battery cycle life as a function of depth of discharge (25 to 75 percent), chopper frequency (100 to 1000 Hz), duty cycle (25 to 87.5 percent), and average discharge current (20 to 260 A). The secondary objective was to determine the types of battery failure modes, if any, were due to the above parameters. The four parameters above were incorporated in a statistically designed test program.

  5. Carbon dioxide control costs for gasification combined-cycle plants in the United States

    SciTech Connect

    Brown, D.R.; Humphreys, K.K.; Vail, L.W.

    1993-06-01

    This study focused on evaluating the cost of recovering CO{sub 2} from coal gasification, combined-cycle (GCC) power plants and transporting the CO{sub 2} in pipelines for disposal in deep ocean water, depleted oil and gas reservoirs, or aquifers. Other fuels and conversion technologies were not evaluated. Technical feasibility, environmental acceptability, and other implementation issues were not addressed in detail. Ocean disposal of CO{sub 2} offers essentially unlimited capacity, but is distant from most US coal-fired power plants and presents environmental concerns at the disposal point. Depleted oil and gas reservoirs are also distant from most US coal-fired power plants and have a more limited disposal capacity,, but were calculated to have a potential capacity more than double that required to dispose of all CO{sub 2} from 830 GCC power plants (380-mwe each) for a period of 40 years. The existence of oil and gas reservoirs provides ``proof`` of the long-term CO{sub 2} confinement potential in these formations. In contrast, aquifer disposal is believed to be significantly riskier. Key concerns are lack of geologic knowledge at depths adequate for CO{sub 2} disposal; uncertainty about geochemical impacts from decreased water pH; and long-term confinement, which is unproven for non-petroleum formations. Carbon dioxide recovery at GCC plants increased the levelized energy cost (LEC) by about one third relative to a reference GCC plant without CO{sub 2} recovery. The transmission distance is the key factor affecting total CO{sub 2} control costs.

  6. Effectiveness and equity impacts of town-wide cycling initiatives in England: a longitudinal, controlled natural experimental study.

    PubMed

    Goodman, Anna; Panter, Jenna; Sharp, Stephen J; Ogilvie, David

    2013-11-01

    Cycling confers health and environmental benefits, but few robust studies have evaluated large-scale programmes to promote cycling. In England, recent years have seen substantial, town-wide cycling initiatives in six Cycling Demonstration Towns (funded 2005-2011) and 12 Cycling Cities and Towns (funded 2008-2011). The initiatives involved mixtures of capital investment (e.g. cycle lanes) and revenue investment (e.g. cycle training), tailored to each town. This controlled before-after natural experimental study used English census data to examine impacts on the prevalence of travelling to work by bicycle and other modes, comparing changes in the intervention towns with changes in three comparison groups (matched towns, unfunded towns and a national comparison group). We also compared effects between more and less deprived areas, and used random-effects meta-analysis to compare intervention effects between towns. Among 1.3 million commuters in 18 intervention towns, we found that the prevalence of cycling to work rose from 5.8% in 2001 to 6.8% in 2011. This represented a significant increase relative to all three comparison groups (e.g. +0.69 (95% CI 0.60,0.77) percentage points for intervention vs. matched towns). Walking to work also increased significantly compared with comparison towns, while driving to work decreased and public transport use was unchanged. These effects were observed across all fifths of area deprivation, with larger relative changes in deprived areas. There was substantial variation in effect sizes between towns, however, and the average town-level effect on cycling was non-significant (+0.29 (-0.26,0.84) percentage points for intervention vs. matched towns). We conclude that to date, cycling to work has increased (and driving to work decreased) in the intervention towns, in a relatively equitable manner. The variation in effects between towns indicates uncertainty regarding the likely impact of comparable investment in future towns

  7. Late - Cycle Injection of Air/Oxygen - Enriched Air for Diesel Exhaust Emissions Control

    SciTech Connect

    Mather, Daniel

    2000-08-20

    Reduce the ''Engine Out'' particulates using the ''In Cylinder'' technique of late cycle auxiliary gas injection (AGI). Reduce the ''Engine Out'' NOx by combining AGI with optimization of fuel injection parameters. Maintain or Improve the Fuel Efficiency.

  8. Arginine starvation in colorectal carcinoma cells: Sensing, impact on translation control and cell cycle distribution.

    PubMed

    Vynnytska-Myronovska, Bozhena O; Kurlishchuk, Yuliya; Chen, Oleh; Bobak, Yaroslav; Dittfeld, Claudia; Hüther, Melanie; Kunz-Schughart, Leoni A; Stasyk, Oleh V

    2016-02-01

    Tumor cells rely on a continued exogenous nutrient supply in order to maintain a high proliferative activity. Although a strong dependence of some tumor types on exogenous arginine sources has been reported, the mechanisms of arginine sensing by tumor cells and the impact of changes in arginine availability on translation and cell cycle regulation are not fully understood. The results presented herein state that human colorectal carcinoma cells rapidly exhaust the internal arginine sources in the absence of exogenous arginine and repress global translation by activation of the GCN2-mediated pathway and inhibition of mTOR signaling. Tumor suppressor protein p53 activation and G1/G0 cell cycle arrest support cell survival upon prolonged arginine starvation. Cells with the mutant or deleted TP53 fail to stop cell cycle progression at defined cell cycle checkpoints which appears to be associated with reduced recovery after durable metabolic stress triggered by arginine withdrawal.

  9. Analysis of supercritical CO{sub 2} cycle control strategies and dynamic response for Generation IV Reactors.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.

    2011-04-12

    The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO{sub 2} recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO{sub 2} reactor heat exchanger (RHX) versus the temperature rise of the CO{sub 2} through the RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO{sub 2} cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO{sub 2} expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO{sub 2} entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO{sub 2} cycle can be successfully adapted to the VHTR and the benefits of the S-CO{sub 2} cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO{sub 2} cycles. Each S-CO{sub 2} cycle is coupled to the VHTR through its own He-to-CO{sub 2} RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle

  10. Cell-Cycle Control of Developmentally Regulated Transcription Factors Accounts for Heterogeneity in Human Pluripotent Cells

    PubMed Central

    Singh, Amar M.; Chappell, James; Trost, Robert; Lin, Li; Wang, Tao; Tang, Jie; Wu, Hao; Zhao, Shaying; Jin, Peng; Dalton, Stephen

    2013-01-01

    Summary Heterogeneity within pluripotent stem cell (PSC) populations is indicative of dynamic changes that occur when cells drift between different states. Although the role of metastability in PSCs is unclear, it appears to reflect heterogeneity in cell signaling. Using the Fucci cell-cycle indicator system, we show that elevated expression of developmental regulators in G1 is a major determinant of heterogeneity in human embryonic stem cells. Although signaling pathways remain active throughout the cell cycle, their contribution to heterogeneous gene expression is restricted to G1. Surprisingly, we identify dramatic changes in the levels of global 5-hydroxymethylcytosine, an unanticipated source of epigenetic heterogeneity that is tightly linked to cell-cycle progression and the expression of developmental regulators. When we evaluated gene expression in differentiating cells, we found that cell-cycle regulation of developmental regulators was maintained during lineage specification. Cell-cycle regulation of developmentally regulated transcription factors is therefore an inherent feature of the mechanisms underpinning differentiation. PMID:24371808

  11. Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control

    NASA Astrophysics Data System (ADS)

    Wu, Hui; Chan, Gerentt; Choi, Jang Wook; Ryu, Ill; Yao, Yan; McDowell, Matthew T.; Lee, Seok Woo; Jackson, Ariel; Yang, Yuan; Hu, Liangbing; Cui, Yi

    2012-05-01

    Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour).

  12. Obliquity-Controlled Water Vapor/Trace Gas Feedback in the Martian Greenhouse Cycle

    NASA Astrophysics Data System (ADS)

    Mischna, M. A.; Baker, V. R.; Milliken, R.; Richardson, M. I.; Lee, C.

    2013-12-01

    We have explored possible mechanisms for the generation of warm, wet climates on early Mars as a result of greenhouse warming by both water vapor and periodic volcanic trace gas emissions, using the Mars Weather Research and Forecasting (MarsWRF) general circulation model. The presence of both water vapor (a strong greenhouse gas) and other trace greenhouse gases (such as SO2) in a predominantly CO2 atmosphere may act, under certain conditions, to elevate surface temperatures above the freezing point of liquid water, at least episodically. The levels of warming obtained in our simulations do not reach the values seen in Johnson et al., (2008, JGR, 113, E08005), nor are they widespread for extended periods. Rather, warming above 273 K is found in more localized environments and for geologically brief periods of time. Such periodic episodes are controlled by two factors. First is the obliquity of the planet, which plays a significant role is ';activating' extant surface water ice reservoirs, allowing levels of atmospheric water vapor to rise when obliquity is high, and fall precipitously when the obliquity is low. During these low-obliquity periods, the atmosphere is all but incapable of supporting warm surface temperatures except for brief episodes localized wholly in the tropics; thus, there is a natural regulator in the obliquity cycle for maintaining periodic warming. Second is the presence of a secondary trace gas 'trigger', like volcanically released SO2, in the atmosphere. In the absence of such a trace gas, water vapor alone appears incapable of raising temperatures above the melting point; however, by temporarily raising the baseline global temperatures (in the absence of warming by water vapor) by 10-15 K, as with SO2, the trigger gas keeps atmospheric temperatures sufficiently warm, especially during nighttime, to maintain levels of water vapor in the atmosphere that provide the needed warming. Furthermore, we find that global warming can be achieved more

  13. Ecohydrological and Biophysical Controls on Carbon Cycling in Two Seasonally Snow-covered Forests

    NASA Astrophysics Data System (ADS)

    Chan, A. M.; Brooks, P. D.; Burns, S. P.; Litvak, M. E.; Blanken, P.; Bowling, D. R.

    2014-12-01

    In many seasonally snow-covered forests, the snowpack is the primary water resource. The snowpack also serves as an insulating layer over the soil, warming soil throughout the winter and preserving moisture conditions from the preceding fall. Therefore, the total amount of water in the snowpack as well as the timing and duration of the snow-covered season are likely to have a strong influence on forest productivity through the regulation of the biophysical environment. We investigated how interannual variation in the amount and timing of seasonal snow cover affect winter carbon efflux and growing season carbon uptake at the Niwot Ridge AmeriFlux site (NWT) in Colorado (3050m a.s.l.; 40˚N) and the Valles Caldera Mixed-Conifer AmeriFlux site (VC) in New Mexico (3003m a.s.l.; 36˚N). The tree species composition at NWT is dominated by Abies lasiocarpa, Picea engelmannii, and Pinus contorta. At VC, the dominant tree species are Pseudotsuga menziesii, Abies concolor, Picea pungens, Pinus strobiformis, Pinus flexilis, Pinus ponderosa, and Populus tremuloides. We used net ecosystem exchange (NEE) and climate data from 1999-2012 at NWT and 2007-2012 at VC to divide each year into the growing season, when NEE is negative, and the winter, when NEE is positive. Snow water equivalent (SWE), precipitation, and duration of snow cover data were obtained from USDA/NRCS SNOTEL sites near each forest. At both sites, the start of the growing season was strongly controlled by air temperature, but growing season NEE was not dependent on the length of the growing season. At NWT, total winter carbon efflux was strongly influenced by both the amount and duration of the snowpack, measured as SWE integrated over time. Years with higher integrated SWE had higher winter carbon efflux and also had warmer soil under the snowpack. These patterns were not seen at VC. However, peak SWE amount was positively correlated with growing season NEE at VC, but not at NWT. These results suggest that

  14. A mutation uncouples the tubulin conformational and GTPase cycles, revealing allosteric control of microtubule dynamics.

    PubMed

    Geyer, Elisabeth A; Burns, Alexander; Lalonde, Beth A; Ye, Xuecheng; Piedra, Felipe-Andres; Huffaker, Tim C; Rice, Luke M

    2015-10-06

    Microtubule dynamic instability depends on the GTPase activity of the polymerizing αβ-tubulin subunits, which cycle through at least three distinct conformations as they move into and out of microtubules. How this conformational cycle contributes to microtubule growing, shrinking, and switching remains unknown. Here, we report that a buried mutation in αβ-tubulin yields microtubules with dramatically reduced shrinking rate and catastrophe frequency. The mutation causes these effects by suppressing a conformational change that normally occurs in response to GTP hydrolysis in the lattice, without detectably changing the conformation of unpolymerized αβ-tubulin. Thus, the mutation weakens the coupling between the conformational and GTPase cycles of αβ-tubulin. By showing that the mutation predominantly affects post-GTPase conformational and dynamic properties of microtubules, our data reveal that the strength of the allosteric response to GDP in the lattice dictates the frequency of catastrophe and the severity of rapid shrinking.

  15. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  16. Effects of Thermal Cycling on Control and Irradiated EPC 2nd Generation GaN FETs

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2013-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling in order to address their reliability for use in space missions. Results of the experimental work are presented and discussed.

  17. Effects of maximal oxygen uptake test and prolonged cycle ergometer exercise on sway density plot of postural control.

    PubMed

    Mello, Roger G T; Oliveira, Liliam F; Nadal, Jurandir

    2009-01-01

    This work aims at testing the influence of the maximal oxygen uptake test and prolonged cycle ergometer exercise on sway density plot (SDP) parameters of postural control. Sixteen healthy male subjects were submitted to stabilometric tests with eye open and closed, before and after two different exercises. The maximal oxygen uptake test caused decrease of the mean duration of peaks in SDP, decreasing the stability level, without modify the rates of central and muscular torque controls. Conversely, 60 min exercise increased the mean time interval between two consecutive peaks in SDP, thus decreasing the control rate but not changing the stability level. Visual privation had a greater effect on body sway than these exercises, which were applied to muscles that are not the main actuators in body sway control. Concluding, the changes in postural control are dependent on the intensity and duration of exercise.

  18. Two-stroke-cycle engines with unsymmetrical control diagram : supercharged engines

    NASA Technical Reports Server (NTRS)

    Zeman, J

    1939-01-01

    As no investigation of supercharging in 2-stroke-cycle engines has been published up to the present, this article is an attempt in that direction, with a view to establishing the mathematical principles and the constructive rules for the design of such engines.

  19. Precision control of soil N cycling via soil functional zone management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managing the soil nitrogen (N) cycle is a major component of agricultural sustainability. Soil functional zone management (SFZM), a novel framework of agroecosystem management, may improve soil N management compared with conventional and no-tillage approaches by focusing on the timing and location (...

  20. Transcriptional control of fungal cell cycle and cellular events by Fkh2, a forkhead transcription factor in an insect pathogen.

    PubMed

    Wang, Juan-Juan; Qiu, Lei; Cai, Qing; Ying, Sheng-Hua; Feng, Ming-Guang

    2015-01-01

    Transcriptional control of the cell cycle by forkhead (Fkh) transcription factors is likely associated with fungal adaptation to host and environment. Here we show that Fkh2, an ortholog of yeast Fkh1/2, orchestrates cell cycle and many cellular events of Beauveria bassiana, a filamentous fungal insect pathogen. Deletion of Fkh2 in B. bassiana resulted in dramatic down-regulation of the cyclin-B gene cluster and hence altered cell cycle (longer G2/M and S, but shorter G0/G1, phases) in unicellular blastospores. Consequently, ΔFkh2 produced twice as many, but smaller, blastospores than wild-type under submerged conditions, and formed denser septa and shorter/broader cells in aberrantly branched hyphae. In these hyphae, clustered genes required for septation and conidiation were remarkedly up-regulated, followed by higher yield and slower germination of aerial conidia. Moreover, ΔFkh2 displayed attenuated virulence and decreased tolerance to chemical and environmental stresses, accompanied with altered transcripts and activities of phenotype-influencing proteins or enzymes. All the changes in ΔFkh2 were restored by Fkh2 complementation. All together, Fkh2-dependent transcriptional control is vital for the adaptation of B. bassiana to diverse habitats of host insects and hence contributes to its biological control potential against arthropod pests. PMID:25955538

  1. Coherent electronic wave packet motion in C(60) controlled by the waveform and polarization of few-cycle laser fields.

    PubMed

    Li, H; Mignolet, B; Wachter, G; Skruszewicz, S; Zherebtsov, S; Süssmann, F; Kessel, A; Trushin, S A; Kling, Nora G; Kübel, M; Ahn, B; Kim, D; Ben-Itzhak, I; Cocke, C L; Fennel, T; Tiggesbäumker, J; Meiwes-Broer, K-H; Lemell, C; Burgdörfer, J; Levine, R D; Remacle, F; Kling, M F

    2015-03-27

    Strong laser fields can be used to trigger an ultrafast molecular response that involves electronic excitation and ionization dynamics. Here, we report on the experimental control of the spatial localization of the electronic excitation in the C_{60} fullerene exerted by an intense few-cycle (4 fs) pulse at 720 nm. The control is achieved by tailoring the carrier-envelope phase and the polarization of the laser pulse. We find that the maxima and minima of the photoemission-asymmetry parameter along the laser-polarization axis are synchronized with the localization of the coherent electronic wave packet at around the time of ionization. PMID:25860740

  2. Water-table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

    NASA Astrophysics Data System (ADS)

    Lipson, D. A.; Zona, D.; Raab, T. K.; Bozzolo, F.; Mauritz, M.; Oechel, W. C.

    2012-01-01

    Drained thaw lake basins (DTLB's) are the dominant land form of the Arctic Coastal Plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in these complex landscapes. Here we report the effects of experimental flooding, along with seasonal and spatial variation in soil chemistry and microbial activity in a DTLB. The flooding treatment generally mirrored the effects of natural landscape variation in water-table height due to microtopography. The flooded portion of the basin had lower dissolved oxygen, lower oxidation-reduction potential (ORP) and higher pH, as did lower elevation areas throughout the entire basin. Similarly, soil pore water concentrations of organic carbon and aromatic compounds were higher in flooded and low elevation areas. Dissolved ferric iron (Fe(III)) concentrations were higher in low elevation areas and responded to the flooding treatment in low areas, only. The high concentrations of soluble Fe(III) in soil pore water were explained by the presence of siderophores, which were much more concentrated in low elevation areas. All the aforementioned variables were correlated, showing that Fe(III) is solubilized in response to anoxic conditions. Dissolved carbon dioxide (CO2) and methane (CH4) concentrations were higher in low elevation areas, but showed only subtle and/or seasonally dependent effects of flooding. In anaerobic laboratory incubations, more CH4 was produced by soils from low and flooded areas, whereas anaerobic CO2

  3. Interhemispheric controls on deep ocean circulation and carbon chemistry during the last two glacial cycles

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Piotrowski, Alexander M.; Galy, Albert; Banakar, Virupaxa K.

    2015-06-01

    Changes in ocean circulation structure, together with biological cycling, have been proposed for trapping carbon in the deep ocean during glacial periods of the Late Pleistocene, but uncertainty remains in the nature and timing of deep ocean circulation changes through glacial cycles. In this study, we use neodymium (Nd) and carbon isotopes from a deep Indian Ocean sediment core to reconstruct water mass mixing and carbon cycling in Circumpolar Deep Water over the past 250 thousand years, a period encompassing two full glacial cycles and including a range of orbital forcing. Building on recent studies, we use reductive sediment leaching supported by measurements on isolated phases (foraminifera and fish teeth) in order to obtain a robust seawater Nd isotope reconstruction. Neodymium isotopes record a changing North Atlantic Deep Water (NADW) component in the deep Indian Ocean that bears a striking resemblance to Northern Hemisphere climate records. In particular, we identify both an approximately in-phase link to Northern Hemisphere summer insolation in the precession band and a longer-term reduction of NADW contributions over the course of glacial cycles. The orbital timescale changes may record the influence of insolation forcing, for example via NADW temperature and/or Antarctic sea ice extent, on deep stratification and mixing in the Southern Ocean, leading to isolation of the global deep oceans from an NADW source during times of low Northern Hemisphere summer insolation. That evidence could support an active role for changing deep ocean circulation in carbon storage during glacial inceptions. However, mid-depth water mass mixing and deep ocean carbon storage were largely decoupled within glacial periods, and a return to an interglacial-like circulation state during marine isotope stage (MIS) 6.5 was accompanied by only minor changes in atmospheric CO2. Although a gradual reduction of NADW export through glacial periods may have produced slow climate feedbacks

  4. Fuel cycle facility control system for the Integral Fast Reactor Program

    SciTech Connect

    Benedict, R.W.; Tate, D.A.

    1993-09-01

    As part of the Integral Fast Reactor (IFR) Fuel Demonstration, a new distributed control system designed, implemented and installed. The Fuel processes are a combination of chemical and machining processes operated remotely. To meet this special requirement, the new control system provides complete sequential logic control motion and positioning control and continuous PID loop control. Also, a centralized computer system provides near-real time nuclear material tracking, product quality control data archiving and a centralized reporting function. The control system was configured to use programmable logic controllers, small logic controllers, personal computers with touch screens, engineering work stations and interconnecting networks. By following a structured software development method the operator interface was standardized. The system has been installed and is presently being tested for operations.

  5. CONTROL OF CELL PROGRESSION THROUGH THE MITOTIC CYCLE BY CARBOHYDRATE PROVISION

    PubMed Central

    Van't Hof, Jack

    1968-01-01

    A stationary phase in the root meristem of excised pea roots was established by prolonged carbohydrate deprivation in sterile culture medium. When the stationary phase had been established, cells that had collected in the G1 period of the mitotic cycle were induced to enter the S stage by subjection to relatively short intervals of carbohydrate provision (sucrose spurts). Progression and cycle location of the G1 cells induced to enter S were measured with tritiated thymidine and radioautography. The results indicated that the number of G1 cells induced to enter S increased directly with the spurt duration and that cells could be positioned and retained in the S and/or G2 periods by varying the duration of the spurt. The data support the hypothesis that S and maybe M stages have a relatively larger dependence on carbohydrate availability, and presumably a greater energy requirement, than G1 and G2. PMID:11905207

  6. mTORC1 Induces Purine Synthesis Through Control of the Mitochondrial Tetrahydrofolate Cycle

    PubMed Central

    Ricoult, Stéphane J.H.; Asara, John M.; Manning, Brendan D.

    2016-01-01

    In response to growth signals, mTOR complex 1 (mTORC1) stimulates anabolic processes underlying cell growth. We found that mTORC1 increases metabolic flux through the de novo purine synthesis pathway in various mouse and human cells, thereby influencing the nucleotide pool available for nucleic acid synthesis. mTORC1 had transcriptional effects on multiple enzymes contributing to purine synthesis, with expression of the mitochondrial tetrahydrofolate (mTHF) cycle enzyme methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) being closely associated with mTORC1 signaling in both normal and cancer cells. MTHFD2 expression and purine synthesis were stimulated by ATF4, which was activated by mTORC1 independent of its canonical induction downstream of eIF2α phosphorylation. Thus, mTORC1 stimulates the mTHF cycle, which contributes one-carbon units to enhance production of purine nucleotides in response to growth signals. PMID:26912861

  7. Coherent control of atomic excitation using off-resonant strong few-cycle pulses

    SciTech Connect

    Jha, Pankaj K.; Eleuch, Hichem; Rostovtsev, Yuri V.

    2010-10-15

    We study the dynamics of a two-level system driven by an off-resonance few-cycle pulse which has a phase jump {phi} at t=t{sub 0}, in contrast to many-cycle pulses, under the nonrotating-wave approximation (NRWA). We give a closed form analytical solution for the evolution of the probability amplitude |C{sub a}(t)| for the upper level. Using the appropriate pulse parameters like the phase jump {phi}, jump time t{sub 0}, pulse width {tau}, frequency {nu}, and Rabi frequency {Omega}{sub 0} the population transfer after the pulse is gone can be optimized and, for the pulse considered here, an enhancement factor of 10{sup 6}-10{sup 8} was obtained.

  8. Spindle-E cycling between nuage and cytoplasm is controlled by Qin and PIWI proteins

    PubMed Central

    Andress, Arlise; Bei, Yanxia; Fonslow, Bryan R.; Giri, Ritika; Wu, Yilong; Yates, John R.

    2016-01-01

    Transposable elements (TEs) are silenced in germ cells by a mechanism in which PIWI proteins generate and use PIWI-interacting ribonucleic acid (piRNA) to repress expression of TE genes. piRNA biogenesis occurs by an amplification cycle in microscopic organelles called nuage granules, which are localized to the outer face of the nuclear envelope. One cofactor required for amplification is the helicase Spindle-E (Spn-E). We found that the Spn-E protein physically associates with the Tudor domain protein Qin and the PIWI proteins Aubergine (Aub) and Argonaute3 (Ago3). Spn-E and Qin proteins are mutually dependent for their exit from nuage granules, whereas Spn-E and both Aub and Ago3 are mutually dependent for their entry or retention in nuage. The result is a dynamic cycling of Spn-E and its associated factors in and out of nuage granules. This implies that nuage granules can be considered to be hubs for active, mobile, and transient complexes. We suggest that this is in some way coupled with the execution of the piRNA amplification cycle. PMID:27091448

  9. Hbp1 regulates the timing of neuronal differentiation during cortical development by controlling cell cycle progression.

    PubMed

    Watanabe, Naoki; Kageyama, Ryoichiro; Ohtsuka, Toshiyuki

    2015-07-01

    In the developing mammalian brain, neural stem cells (NSCs) initially expand the progenitor pool by symmetric divisions. NSCs then shift from symmetric to asymmetric division and commence neurogenesis. Although the precise mechanisms regulating the developmental timing of this transition have not been fully elucidated, gradual elongation in the length of the cell cycle and coinciding accumulation of determinants that promote neuronal differentiation might function as a biological clock that regulates the onset of asymmetric division and neurogenesis. We conducted gene expression profiling of embryonic NSCs in the cortical regions and found that expression of high mobility group box transcription factor 1 (Hbp1) was upregulated during neurogenic stages. Induced conditional knockout mice of Hbp1, generated by crossing with Nestin-CreER(T2) mice, exhibited a remarkable dilatation of the telencephalic vesicles with a tangentially expanded ventricular zone and a thinner cortical plate containing reduced numbers of neurons. In these Hbp1-deficient mouse embryos, neural stem/progenitor cells continued to divide with a shorter cell cycle length. Moreover, downstream target genes of the Wnt signaling, such as cyclin D1 (Ccnd1) and c-jun (Jun), were upregulated in the germinal zone of the cortical regions. These results indicate that Hbp1 plays a crucial role in regulating the timing of cortical neurogenesis by elongating the cell cycle and that it is essential for normal cortical development.

  10. Cell cycle-dependent phosphorylation of Sec4p controls membrane deposition during cytokinesis.

    PubMed

    Lepore, Dante; Spassibojko, Olya; Pinto, Gabrielle; Collins, Ruth N

    2016-09-12

    Intracellular trafficking is an essential and conserved eukaryotic process. Rab GTPases are a family of proteins that regulate and provide specificity for discrete membrane trafficking steps by harnessing a nucleotide-bound cycle. Global proteomic screens have revealed many Rab GTPases as phosphoproteins, but the effects of this modification are not well understood. Using the Saccharomyces cerevisiae Rab GTPase Sec4p as a model, we have found that phosphorylation negatively regulates Sec4p function by disrupting the interaction with the exocyst complex via Sec15p. We demonstrate that phosphorylation of Sec4p is a cell cycle-dependent process associated with cytokinesis. Through a genomic kinase screen, we have also identified the polo-like kinase Cdc5p as a positive regulator of Sec4p phosphorylation. Sec4p spatially and temporally localizes with Cdc5p exclusively when Sec4p phosphorylation levels peak during the cell cycle, indicating Sec4p is a direct Cdc5p substrate. Our data suggest the physiological relevance of Sec4p phosphorylation is to facilitate the coordination of membrane-trafficking events during cytokinesis. PMID:27621363

  11. Photosynthesis in Rhodospirillum rubrum. III. Metabolic Control of Reductive Pentose Phosphate and Tricarboxylic Acid Cycle Enzymes 1

    PubMed Central

    Anderson, Louise; Fuller, R. C.

    1967-01-01

    Enzymes of the reductive pentose phosphate cycle including ribulose-diphosphate carboxylase, ribulose-5-phosphate kinase, ribose-5-phosphate isomerase, aldolase, glyceraldehyde-3-phosphate dehydrogenase and alkaline fructose-1,6-diphos-phatase were shown to be present in autotrophically grown Rhodospirillum rubrum. Enzyme levels were measured in this organism grown photo- and dark heterotrophically as well. Several, but not all, of these enzymes appeared to be under metabolic control, mediated by exogenous carbon and nitrogen compounds. Light had no effect on the presence or levels of any of these enzymes in this photosynthetic bacterium. The enzymes of the tricarboxylic acid cycle and enolase were shown to be present in R. rubrum cultured aerobically, autotrophically, or photoheterotrophically, both in cultures evolving hydrogen and under conditions where hydrogen evolution is not observed. Light had no clearly demonstrable effect on the presence or levels of any of these enzymes. PMID:6042359

  12. Influence of menstrual cycle phase on muscle metaboreflex control of cardiac baroreflex sensitivity, heart rate and blood pressure in humans.

    PubMed

    Hartwich, Doreen; Aldred, Sarah; Fisher, James P

    2013-01-01

    We sought to determine whether menstrual cycle phase influences muscle metaboreflex control of spontaneous cardiac baroreflex sensitivity (cBRS), blood pressure (BP) and heart rate (HR). Twenty-three young women not taking oral contraceptives were studied during the early (EF; low oestrogen, low progesterone) and late follicular menstrual phases (LF; high oestrogen, low progesterone). Protocol 1 consisted of leg cycling at low (21 ± 2 W) and moderate workloads (71 ± 3 W) in free-flow conditions and with partial flow restriction (bilateral thigh-cuff inflation at 100 mmHg) to activate the muscle metaboreflex. Protocol 2 consisted of rhythmic hand-grip exercise with incremental upper arm-cuff inflation (0, 80, 100 and 120 mmHg) to elicit graded metaboreflex activation. Both protocols were followed by post-exercise ischaemia. Leg cycling decreased cBRS (EF, 20 ± 5, 6 ± 1 and 1 ± 0.1 ms mmHg(-1); and LF, 19 ± 3, 6 ± 0.4, 1 ± 0.1 ms mmHg(-1) during rest, low- and moderate-intensity leg cycling, respectively) and increased HR in an intensity-dependent manner, while BP remained unchanged. Partial flow restriction during leg cycling decreased cBRS, and increased HR and BP. During post-exercise ischaemia, HR and BP remained elevated, while cBRS remained suppressed (EF, 4.2 ± 0.6 ms mmHg(-1); and LF, 4.7 ± 0.5 ms mmHg(-1); P < 0.05 versus rest). Cardiac baroreflex sensitivity was unchanged during hand-grip with and without partial flow restriction and post-exercise ischaemia. No differences in cBRS, HR or BP responses were observed between EF and LF at any time during either protocol. These data indicate that endogenous fluctuations in oestrogen between the EF and LF phases of the menstrual cycle do not influence muscle metaboreflex control of cBRS, BP or HR in young women.

  13. Irrigation and Fertilization Controls on Critical Zone Carbon and Nitrogen cycles in Harvested Ecosystems

    NASA Astrophysics Data System (ADS)

    Parolari, A.; Katul, G. G.; Porporato, A. M.

    2014-12-01

    Feedbacks between hydrology, soil biogeochemistry, and primary productivity raise questions regarding the broader impact of human modifications to one or more of these critical zone processes. In particular, irrigation and nitrogen fertilization are used simultaneously to stimulate agricultural productivity and biomass export; however, together they may lead to unintended downstream consequences such as increased nitrogen leaching or greenhouse gas release. To quantify such trade-offs among ecosystem services and to identify optimal agricultural management practices, an ecosystem model coupling the water, carbon, and nitrogen cycles is studied. The model is forced by stochastic climate and periodic management interventions that include irrigation, fertilization, and harvest. Steady-state solutions of ecosystems under rotational harvest are developed, demonstrating that these ecosystems operate in a limit-cycle. Under constant fertilization and soil moisture conditions, the model predicts an optimal rotation length associated with maximum yield and maximum ecosystem nitrogen use efficiency. Through plant-soil feedbacks mediated by the harvest, intermediate rotation lengths promote short periods of immobilization, which stimulates mineral nitrogen retention. In these systems, increased soil moisture increases non-productive nitrogen losses, especially under long rotations, where mineral nitrogen availability is greatest. Time-variable water and nitrogen input scenarios are also considered and suggest the possibility of an optimal irrigation-fertilization strategy that balances productivity, which provides an economic benefit, and leaching, which may have consequences for aquatic ecosystems in receiving waters. These results highlight several soil C-N cycle responses to management practices that influence the provision of and trade-off between ecosystem services, namely primary productivity and mineral nitrogen export.

  14. Epigenetic control of viral life-cycle by a DNA-methylation dependent transcription factor.

    PubMed

    Flower, Kirsty; Thomas, David; Heather, James; Ramasubramanyan, Sharada; Jones, Susan; Sinclair, Alison J

    2011-01-01

    Epstein-Barr virus (EBV) encoded transcription factor Zta (BZLF1, ZEBRA, EB1) is the prototype of a class of transcription factor (including C/EBPalpha) that interact with CpG-containing DNA response elements in a methylation-dependent manner. The EBV genome undergoes a biphasic methylation cycle; it is extensively methylated during viral latency but is reset to an unmethylated state following viral lytic replication. Zta is expressed transiently following infection and again during the switch between latency and lytic replication. The requirement for CpG-methylation at critical Zta response elements (ZREs) has been proposed to regulate EBV replication, specifically it could aid the activation of viral lytic gene expression from silenced promoters on the methylated genome during latency in addition to preventing full lytic reactivation from the non-methylated EBV genome immediately following infection. We developed a computational approach to predict the location of ZREs which we experimentally assessed using in vitro and in vivo DNA association assays. A remarkably different binding motif is apparent for the CpG and non-CpG ZREs. Computational prediction of the location of these binding motifs in EBV revealed that the majority of lytic cycle genes have at least one and many have multiple copies of methylation-dependent CpG ZREs within their promoters. This suggests that the abundance of Zta protein coupled with the methylation status of the EBV genome act together to co-ordinate the expression of lytic cycle genes at the majority of EBV promoters. PMID:22022468

  15. Arsenic control during aquifer storage recovery cycle tests in the Floridan Aquifer.

    PubMed

    Mirecki, June E; Bennett, Michael W; López-Baláez, Marie C

    2013-01-01

    Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H2 S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer.

  16. Soil Salinity Controls on Water and Carbon Cycling by Sunflower Plants

    NASA Astrophysics Data System (ADS)

    Runkle, B.; Liang, X.; Dracup, J.; Hao, F.; Zeng, A.; Zhang, J.; He, B.; Oki, T.

    2007-12-01

    Agricultural effects on water cycling are of great importance for regional water resources management. These effects vary based on local soil and climate conditions, and are particularly modulated by high soil salinity levels, which stress plant growth and change their water use efficiency. Increasing salinization is predicted under hotter, drier conditions resulting from global climate change and from increased societal pressure on agricultural lands. This increased ionic presence creates a higher soil osmotic pressure that increases the resistance to water flow through the plant. This change also impacts the assimilation of carbon dioxide through the stomatal opening, and so affects rates of both photosynthesis and transpiration. Current agricultural and land-surface models that account for salinity do so in an overly empirical manner that cannot account for changes at different time scales in meteorological conditions. They tend to be ill equipped to examine how changing carbon dioxide levels may modify a plant's response to soil salinity. As a result, we present a new model of soil-vegetation- atmosphere water transfer that explicitly incorporates the role of soil salinity in changing this system's behavior. This model will allow for much greater flexibility in examining how vegetation may change the local water cycle under the joint impacts of both salinity and climate change. This model is supported by field research on the effects of salinity on sunflower plants in a large irrigation district in Inner Mongolia, China. Results presented include the role of salinity in changing stomatal regulation of water use efficiency, sub-canopy changes in leaf pressure, and changes in root activity. Modeling at sub-hourly time scales allows for a more precise understanding of how soil salinity changes the diurnal cycle of plant water use.

  17. Arsenic control during aquifer storage recovery cycle tests in the Floridan Aquifer.

    PubMed

    Mirecki, June E; Bennett, Michael W; López-Baláez, Marie C

    2013-01-01

    Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H2 S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer. PMID:23106789

  18. Nonlinear optics with phase-controlled pulses in the sub-two-cycle regime.

    PubMed

    Morgner, U; Ell, R; Metzler, G; Schibli, T R; Kärtner, F X; Fujimoto, J G; Haus, H A; Ippen, E P

    2001-06-11

    Nonlinear optical effects due to the phase between carrier and envelope are observed with 5 fs pulses from a Kerr-lens mode-locked Ti:sapphire laser. These sub-two-cycle pulses with octave spanning spectra are the shortest pulses ever generated directly from a laser oscillator. Detection of the carrier-envelope phase slip is made possible by simply focusing the short pulses directly from the oscillator into a BBO crystal. As a further example of nonlinear optics with such short pulses, the interference between second- and third-harmonic components is also demonstrated.

  19. Environmental controls on nitrogen and sulfur cycles in surficial aquatic sediments.

    PubMed

    Gu, Chuanhui; Laverman, Anniet M; Pallud, Céline E

    2012-01-01

    Enhanced anthropogenic inputs of nitrogen (N) and sulfur (S) have disturbed their biogeochemical cycling in aquatic and terrestrial ecosystems. The N and S cycles interact with one another through competition for labile forms of organic carbon between nitrate-reducing and sulfate-reducing bacteria. Furthermore, the N and S cycles could interact through nitrate [Formula: see text] reduction coupled to S oxidation, consuming [Formula: see text] and producing sulfate [Formula: see text] The research questions of this study were: (1) what are the environmental factors explaining variability in N and S biogeochemical reaction rates in a wide range of surficial aquatic sediments when [Formula: see text] and [Formula: see text] are present separately or simultaneously, (2) how the N and S cycles could interact through S oxidation coupled to [Formula: see text] reduction, and (3) what is the extent of sulfate reduction inhibition by nitrate, and vice versa. The N and S biogeochemical reaction rates were measured on intact surface sediment slices using flow-through reactors. The two terminal electron acceptors [Formula: see text] and [Formula: see text] were added either separately or simultaneously and [Formula: see text] and [Formula: see text] reduction rates as well as [Formula: see text] reduction linked to S oxidation were determined. We used redundancy analysis, to assess how environmental variables were related to these rates. Our analysis showed that overlying water pH and salinity were two dominant environmental factors that explain 58% of the variance in the N and S biogeochemical reaction rates when [Formula: see text] and [Formula: see text] were both present. When [Formula: see text] and [Formula: see text] were added separately, however, sediment N content in addition to pH and salinity accounted for 62% of total variance of the biogeochemical reaction rates. The [Formula: see text] addition had little effect on [Formula: see text] reduction; neither did the

  20. The C. elegans hox gene lin-39 controls cell cycle progression during vulval development.

    PubMed

    Roiz, Daniel; Escobar-Restrepo, Juan Miguel; Leu, Philipp; Hajnal, Alex

    2016-10-01

    Cell fate specification during organogenesis is usually followed by a phase of cell proliferation to produce the required number of differentiated cells. The Caenorhabditis elegans vulva is an excellent model to study how cell fate specification and cell proliferation are coordinated. The six vulval precursor cells (VPCs) are born at the first larval stage, but they arrest in the G1 phase of the cell cycle until the beginning of the third larval stage, when their fates are specified and the three proximal VPCs proliferate to generate 22 vulval cells. An epidermal growth factor (EGF) signal from the gonadal anchor cell combined with lateral DELTA/NOTCH signaling between the VPCs determine the primary (1°) and secondary (2°) fates, respectively. The hox gene lin-39 plays a key role in integrating these spatial patterning signals and in maintaining the VPCs as polarized epithelial cells. Using a fusion-defective eff-1(lf) mutation to keep the VPCs polarized, we find that VPCs lacking lin-39 can neither activate lateral NOTCH signaling nor proliferate. LIN-39 promotes cell cycle progression through two distinct mechanisms. First, LIN-39 maintains the VPCs competent to proliferate by inducing cdk-4 cdk and cye-1 cyclinE expression via a non-canonical HOX binding motif. Second, LIN-39 activates in the adjacent VPCs the NOTCH signaling pathway, which promotes VPC proliferation independently of LIN-39. The hox gene lin-39 is therefore a central node in a regulatory network coordinating VPC differentiation and proliferation.

  1. Substrate Utilization and Cycling Performance Following Palatinose™ Ingestion: A Randomized, Double-Blind, Controlled Trial.

    PubMed

    König, Daniel; Zdzieblik, Denise; Holz, Anja; Theis, Stephan; Gollhofer, Albert

    2016-01-01

    (1) OBJECTIVE: To compare the effects of isomaltulose (Palatinose™, PSE) vs. maltodextrin (MDX) ingestion on substrate utilization during endurance exercise and subsequent time trial performance; (2) METHODS: 20 male athletes performed two experimental trials with ingestion of either 75 g PSE or MDX 45 min before the start of exercise. The exercise protocol consisted of 90 min cycling (60% VO₂max) followed by a time trial; (3) RESULTS: Time trial finishing time (-2.7%, 90% CI: ±3.0%, 89% likely beneficial; p = 0.147) and power output during the final 5 min (+4.6%, 90% CI: ±4.0%, 93% likely beneficial; p = 0.053) were improved with PSE compared with MDX. The blood glucose profile differed between trials (p = 0.013) with PSE resulting in lower glycemia during rest (95%-99% likelihood) and higher blood glucose concentrations during exercise (63%-86% likelihood). In comparison to MDX, fat oxidation was higher (88%-99% likelihood; p = 0.005) and carbohydrate oxidation was lower following PSE intake (85%-96% likelihood; p = 0.002). (4) CONCLUSION: PSE maintained a more stable blood glucose profile and higher fat oxidation during exercise which resulted in improved cycling performance compared with MDX. These results could be explained by the slower availability and the low-glycemic properties of Palatinose™ allowing a greater reliance on fat oxidation and sparing of glycogen during the initial endurance exercise. PMID:27347996

  2. Oxygen Isotope in Phosphate an Indicator of Phosphorous Cycling in the Ocean - Controls, and Applications

    NASA Astrophysics Data System (ADS)

    Paytan, A.; Roberts, K.; Defforey, D.; McLaughlin, K.; Lomas, M. W.; Church, M. J.; Mackey, K. R.

    2012-12-01

    In order to better constrain the parameters affecting oxygen isotope exchange between water and phosphate via biochemical reactions a set of culture experiments were conducted. Different species of phytoplankton were grown in seawater at various temperatures, light levels, and phosphate concentrations. The oxygen isotopic composition in the phosphate source, algal cells, and the isotopic composition oxygen in the dissolved inorganic phosphate (DIP) were measured. Results showing the effect of species, temperature, light and P availability on intracellular oxygen isotope exchange between phosphorus compounds and water will be presented. The effect of these parameters on the utility of the oxygen isotopic composition of phosphate as a tracer of phosphate utilization rate in the ocean will be discussed. This information is fundamental to any application of isotopic composition of oxygen of dissolved inorganic or organic phosphate to quantify the dynamics of phosphorus cycling in aquatic systems. The data will be utilized to investigate seasonal changes in phosphate sources and cycling in the open ocean and how these relate to phytoplankton abundance, hydrography, and nutrient concentrations.

  3. Unique pharmacological actions of atypical neuroleptic quetiapine: possible role in cell cycle/fate control

    PubMed Central

    Kondo, M A; Tajinda, K; Colantuoni, C; Hiyama, H; Seshadri, S; Huang, B; Pou, S; Furukori, K; Hookway, C; Jaaro-Peled, H; Kano, S-i; Matsuoka, N; Harada, K; Ni, K; Pevsner, J; Sawa, A

    2013-01-01

    Quetiapine is an atypical neuroleptic with a pharmacological profile distinct from classic neuroleptics that function primarily via blockade of dopamine D2 receptors. In the United States, quetiapine is currently approved for treating patients with schizophrenia, major depression and bipolar I disorder. Despite its widespread use, its cellular effects remain elusive. To address possible mechanisms, we chronically treated mice with quetiapine, haloperidol or vehicle and examined quetiapine-specific gene expression change in the frontal cortex. Through microarray analysis, we observed that several groups of genes were differentially expressed upon exposure to quetiapine compared with haloperidol or vehicle; among them, Cdkn1a, the gene encoding p21, exhibited the greatest fold change relative to haloperidol. The quetiapine-induced downregulation of p21/Cdkn1a was confirmed by real-time polymerase chain reaction and in situ hybridization. Consistent with single gene-level analyses, functional group analyses also indicated that gene sets associated with cell cycle/fate were differentially regulated in the quetiapine-treated group. In cortical cell cultures treated with quetiapine, p21/Cdkn1a was significantly downregulated in oligodendrocyte precursor cells and neurons, but not in astrocytes. We propose that cell cycle-associated intervention by quetiapine in the frontal cortex may underlie a unique efficacy of quetiapine compared with typical neuroleptics. PMID:23549417

  4. Substrate Utilization and Cycling Performance Following Palatinose™ Ingestion: A Randomized, Double-Blind, Controlled Trial

    PubMed Central

    König, Daniel; Zdzieblik, Denise; Holz, Anja; Theis, Stephan; Gollhofer, Albert

    2016-01-01

    (1) Objective: To compare the effects of isomaltulose (Palatinose™, PSE) vs. maltodextrin (MDX) ingestion on substrate utilization during endurance exercise and subsequent time trial performance; (2) Methods: 20 male athletes performed two experimental trials with ingestion of either 75 g PSE or MDX 45 min before the start of exercise. The exercise protocol consisted of 90 min cycling (60% VO2max) followed by a time trial; (3) Results: Time trial finishing time (−2.7%, 90% CI: ±3.0%, 89% likely beneficial; p = 0.147) and power output during the final 5 min (+4.6%, 90% CI: ±4.0%, 93% likely beneficial; p = 0.053) were improved with PSE compared with MDX. The blood glucose profile differed between trials (p = 0.013) with PSE resulting in lower glycemia during rest (95%–99% likelihood) and higher blood glucose concentrations during exercise (63%–86% likelihood). In comparison to MDX, fat oxidation was higher (88%–99% likelihood; p = 0.005) and carbohydrate oxidation was lower following PSE intake (85%–96% likelihood; p = 0.002). (4) Conclusion: PSE maintained a more stable blood glucose profile and higher fat oxidation during exercise which resulted in improved cycling performance compared with MDX. These results could be explained by the slower availability and the low-glycemic properties of Palatinose™ allowing a greater reliance on fat oxidation and sparing of glycogen during the initial endurance exercise. PMID:27347996

  5. mTORC1 induces purine synthesis through control of the mitochondrial tetrahydrofolate cycle.

    PubMed

    Ben-Sahra, Issam; Hoxhaj, Gerta; Ricoult, Stéphane J H; Asara, John M; Manning, Brendan D

    2016-02-12

    In response to growth signals, mechanistic target of rapamycin complex 1 (mTORC1) stimulates anabolic processes underlying cell growth. We found that mTORC1 increases metabolic flux through the de novo purine synthesis pathway in various mouse and human cells, thereby influencing the nucleotide pool available for nucleic acid synthesis. mTORC1 had transcriptional effects on multiple enzymes contributing to purine synthesis, with expression of the mitochondrial tetrahydrofolate (mTHF) cycle enzyme methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) being closely associated with mTORC1 signaling in both normal and cancer cells. MTHFD2 expression and purine synthesis were stimulated by activating transcription factor 4 (ATF4), which was activated by mTORC1 independent of its canonical induction downstream of eukaryotic initiation factor 2α eIF2α phosphorylation. Thus, mTORC1 stimulates the mTHF cycle, which contributes one-carbon units to enhance production of purine nucleotides in response to growth signals. PMID:26912861

  6. Differential menstrual cycle regulation of hypothalamic-pituitary-adrenal axis in women with premenstrual syndrome and controls.

    PubMed

    Roca, Catherine A; Schmidt, Peter J; Altemus, Margaret; Deuster, Patricia; Danaceau, Merry A; Putnam, Karen; Rubinow, David R

    2003-07-01

    Previous studies in animals indicate that reproductive steroids are potent modulators of the hypothalamic-pituitary-adrenal (HPA) axis, a physiologic system that is typically dysregulated in affective disorders, such as major depression. Determination of the role of reproductive steroids in HPA axis regulation in humans is of importance when attempting to understand the pathophysiology of premenstrual syndrome (PMS), a disorder characterized by affective symptoms during the luteal phase of the menstrual cycle. We performed two studies using treadmill exercise stress testing to determine the effect of menstrual cycle phase and diagnosis on the HPA axis in women with PMS and controls and the role of gonadal steroids in HPA axis modulation in control women. The results of these studies indicate that women with PMS fail to show the normal increased HPA axis response to exercise during the luteal phase and that progesterone, not estradiol, produces increased HPA axis response to treadmill stress testing in control women. These data demonstrate that women with PMS, when symptomatic, appear to have an abnormal response to progesterone and, furthermore, do not display the HPA axis abnormalities characteristic of major depression.

  7. Reproductive Requirements and Life Cycle of Iberorhyzobius rondensis (Coleoptera: Coccinellidae), Potential Biological Control Agent of Matsucoccus feytaudi (Hemiptera: Matsucoccidae).

    PubMed

    Tavares, C; Jactel, H; van Halder, I; Branco, M

    2015-06-01

    Several pine bast scales (Hemiptera: Matsucoccidae) are important pests of pine trees in the Northern Hemisphere. Some species are invasive and cause significant economic and environmental impacts. Such is the case with Matsucoccus feytaudi Ducasse, an invasive pest of maritime pine forests in Southeastern France, Italy, and Corsica. The ladybird Iberorhyzobius rondensis (Eizaguirre) is a recently described species that is endemic to the Iberian Peninsula and is a potential candidate for the biological control of M. feytaudi. However, little is known of the biology of I. rondensis. As part of the risk assessment study for a classical biological control program, the phenology and reproductive mechanisms of the beetle were analyzed. I. rondensis is univoltine and is seasonally synchronized with the phenology of the prey M. feytaudi, which is also univoltine. An obligatory reproductive diapause of 5-6 mo and the need to feed on the eggs of the prey to begin oviposition emerged as the two primary mechanisms that assure life cycle synchronization of the ladybird with its prey. Female fecundity was also higher when the ladybirds were fed M. feytaudi eggs. Life cycle synchronization with M. feytaudi and reproduction triggered by consumption of prey eggs indicate that I. rondensis is a promising biological control agent of the pine bast scale. PMID:26313991

  8. Reproductive Requirements and Life Cycle of Iberorhyzobius rondensis (Coleoptera: Coccinellidae), Potential Biological Control Agent of Matsucoccus feytaudi (Hemiptera: Matsucoccidae).

    PubMed

    Tavares, C; Jactel, H; van Halder, I; Branco, M

    2015-06-01

    Several pine bast scales (Hemiptera: Matsucoccidae) are important pests of pine trees in the Northern Hemisphere. Some species are invasive and cause significant economic and environmental impacts. Such is the case with Matsucoccus feytaudi Ducasse, an invasive pest of maritime pine forests in Southeastern France, Italy, and Corsica. The ladybird Iberorhyzobius rondensis (Eizaguirre) is a recently described species that is endemic to the Iberian Peninsula and is a potential candidate for the biological control of M. feytaudi. However, little is known of the biology of I. rondensis. As part of the risk assessment study for a classical biological control program, the phenology and reproductive mechanisms of the beetle were analyzed. I. rondensis is univoltine and is seasonally synchronized with the phenology of the prey M. feytaudi, which is also univoltine. An obligatory reproductive diapause of 5-6 mo and the need to feed on the eggs of the prey to begin oviposition emerged as the two primary mechanisms that assure life cycle synchronization of the ladybird with its prey. Female fecundity was also higher when the ladybirds were fed M. feytaudi eggs. Life cycle synchronization with M. feytaudi and reproduction triggered by consumption of prey eggs indicate that I. rondensis is a promising biological control agent of the pine bast scale.

  9. DC-pulsed voltage electrochemical method based on duty cycle self-control for producing TERS gold tips

    NASA Astrophysics Data System (ADS)

    Vasilchenko, V. E.; Kharintsev, S. S.; Salakhov, M. Kh

    2013-12-01

    This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide.

  10. Coordinated control of Notch/Delta signalling and cell cycle progression drives lateral inhibition-mediated tissue patterning

    PubMed Central

    Hadjivasiliou, Zena; Bonin, Hope; He, Li; Perrimon, Norbert; Charras, Guillaume; Baum, Buzz

    2016-01-01

    Coordinating cell differentiation with cell growth and division is crucial for the successful development, homeostasis and regeneration of multicellular tissues. Here, we use bristle patterning in the fly notum as a model system to explore the regulatory and functional coupling of cell cycle progression and cell fate decision-making. The pattern of bristles and intervening epithelial cells (ECs) becomes established through Notch-mediated lateral inhibition during G2 phase of the cell cycle, as neighbouring cells physically interact with each other via lateral contacts and/or basal protrusions. Since Notch signalling controls cell division timing downstream of Cdc25, ECs in lateral contact with a Delta-expressing cell experience higher levels of Notch signalling and divide first, followed by more distant neighbours, and lastly Delta-expressing cells. Conversely, mitotic entry and cell division makes ECs refractory to lateral inhibition signalling, fixing their fate. Using a combination of experiments and computational modelling, we show that this reciprocal relationship between Notch signalling and cell cycle progression acts like a developmental clock, providing a delimited window of time during which cells decide their fate, ensuring efficient and orderly bristle patterning. PMID:27226324

  11. Mitochondrial Development during Life Cycle Differentiation of African Trypanosomes: Evidence for a Kinetoplast-dependent Differentiation Control Point

    PubMed Central

    Timms, Mark W.; van Deursen, Frederick J.; Hendriks, Edward F.; Matthews, Keith R.

    2002-01-01

    Life cycle differentiation of African trypanosomes entails developmental regulation of mitochondrial activity. This requires regulation of the nuclear genome and the kinetoplast, the trypanosome's unusual mitochondrial genome. To investigate the potential cross talk between the nuclear and mitochondrial genome during the events of differentiation, we have 1) disrupted expression of a nuclear-encoded component of the cytochrome oxidase (COX) complex; and 2) generated dyskinetoplastid cells, which lack a mitochondrial genome. Using RNA interference (RNAi) and by disrupting the nuclear COX VI gene, we demonstrate independent regulation of COX component mRNAs encoded in the nucleus and kinetoplast. However, two independent approaches (acriflavine treatment and RNA interference ablation of mitochondrial topoisomerase II) failed to establish clonal lines of dyskinetoplastid bloodstream forms. Nevertheless, dyskinetoplastid forms generated in vivo could undergo two life cycle differentiation events: transition from bloodstream slender to stumpy forms and the initiation of transformation to procyclic forms. However, they subsequently arrested at a specific point in this developmental program before cell cycle reentry. These results provide strong evidence for a requirement for kinetoplast DNA in the bloodstream and for a kinetoplast-dependent control point during differentiation to procyclic forms. PMID:12388771

  12. Control of luteal relaxin release by prostaglandin F2 alpha: differences in the sow cycle and pregnancy.

    PubMed

    Bagnell, C A; Baker, N K; McMurtry, J P; Brocht, D M; Lewis, G S

    1990-06-01

    The effect of an in vivo prostaglandin F2 alpha (PGF2 alpha) challenge in pregnant and cyclic sows was compared to determine whether PGF2 alpha-induced release of relaxin (RLX) from the corpus luteum (CL) in late pregnancy is also effective during the cycle. Ovarian venous RLX and progesterone were monitored by radioimmunoassay and RLX localized in the CL by immunohistochemistry. In Day 108 pregnant sows, infusion of PGF2 alpha (100 micrograms) into the ovarian artery resulted in an immediate and sustained rise in ovarian venous RLX with an initial decline in progesterone levels by 30 min which then returned to pretreatment levels. In Day 13 or 15 cyclic sows with functional corpora lutea (i.e., elevated progesterone), RLX was undetectable in ovarian venous blood after 100 micrograms of PGF2 alpha. Administration of PGF2 alpha via either the jugular vein or intramuscular route was also ineffective in releasing RLX from the CL of the cycle. The intensity of RLX immunostaining of the CL was similar in saline and PGF2 alpha-treated sows. These studies indicate that the control of RLX release from the sow CL differs in the estrous cycle and pregnancy.

  13. Thermodynamic and dynamic controls on changes in the zonally anomalous hydrological cycle

    NASA Astrophysics Data System (ADS)

    Wills, Robert C.; Byrne, Michael P.; Schneider, Tapio

    2016-05-01

    The wet gets wetter, dry gets drier paradigm explains the expected moistening of the extratropics and drying of the subtropics as the atmospheric moisture content increases with global warming. Here we show, using precipitation minus evaporation (P - E) data from climate models, that it cannot be extended to apply regionally to deviations from the zonal mean. Wet and dry zones shift substantially in response to shifts in the stationary-eddy circulations that cause them. Additionally, atmospheric circulation changes lead to a smaller increase in the zonal variance of P - E than would be expected from atmospheric moistening alone. The P - E variance change can be split into dynamic and thermodynamic components through an analysis of the atmospheric moisture budget. This reveals that a weakening of stationary-eddy circulations and changes in the zonal variation of transient-eddy moisture fluxes moderate the strengthening of the zonally anomalous hydrological cycle with global warming.

  14. Intensified Weathering Control of Carbon Cycle along an Earthworm Invasion Chronosequence: Preliminary Data

    NASA Astrophysics Data System (ADS)

    Fernandez, C.; Yoo, K.; Aufdenkampe, A. K.; Hale, C.

    2009-12-01

    coupling of chemical weathering and soil carbon cycle. Our ultimate goal is to understand the holistic response of mineral weathering and carbon cycle to accelerated soil mixing by earthworm invasion.

  15. Identifying sources and processes controlling the sulphur cycle in the Canyon Creek watershed, Alberta, Canada.

    PubMed

    Nightingale, Michael; Mayer, Bernhard

    2012-01-01

    Sources and processes affecting the sulphur cycle in the Canyon Creek watershed in Alberta (Canada) were investigated. The catchment is important for water supply and recreational activities and is also a source of oil and natural gas. Water was collected from 10 locations along an 8 km stretch of Canyon Creek including three so-called sulphur pools, followed by the chemical and isotopic analyses on water and its major dissolved species. The δ(2)H and δ(18)O values of the water plotted near the regional meteoric water line, indicating a meteoric origin of the water and no contribution from deeper formation waters. Calcium, magnesium and bicarbonate were the dominant ions in the upstream portion of the watershed, whereas sulphate was the dominant anion in the water from the three sulphur pools. The isotopic composition of sulphate (δ(34)S and δ(18)O) revealed three major sulphate sources with distinct isotopic compositions throughout the catchment: (1) a combination of sulphate from soils and sulphide oxidation in the bedrock in the upper reaches of Canyon Creek; (2) sulphide oxidation in pyrite-rich shales in the lower reaches of Canyon Creek and (3) dissolution of Devonian anhydrite constituting the major sulphate source for the three sulphur pools in the central portion of the watershed. The presence of H(2)S in the sulphur pools with δ(34)S values ∼30 ‰ lower than those of sulphate further indicated the occurrence of bacterial (dissimilatory) sulphate reduction. This case study reveals that δ(34)S values of surface water systems can vary by more than 20 ‰ over short geographic distances and that isotope analyses are an effective tool to identify sources and processes that govern the sulphur cycle in watersheds.

  16. Controls of the Northern Hemisphere Hadley circulation over the last five glacial cycles

    NASA Astrophysics Data System (ADS)

    Meckler, A. N.; Roehl, U.; Adkins, J. F.; Haug, G. H.

    2012-12-01

    Sediments off the coast of Mauritania have proven to be sensitive recorders of climate in the adjacent Sahel zone and Saharan desert. It has been shown that climate in this region is highly sensitive to both local insolation forcing, dominated by orbital precession, and high latitude millennial-scale cooling events. However, most available high-resolution records are relatively short, covering at most the last glacial cycle. Here we extend the existing grain-size-based humidity record from core GeoB7920-2 (Tjallingii et al., Nature Geoscience, 2008) back to 550 kyr BP, using sediments from ODP Site 658 at the same location. We employ the XRF-scanning-derived Zr/Al ratio as a proxy for grain-size, which corresponds well to the published humidity index over the last 110 kyr. Grain-size is expected to be a mixed signal of continental aridity and wind strength, whereby the Northeasterly trade winds are the dominant source of dust at this site. The data from Site 658 should therefore reflect the northern components of the low-latitude Hadley circulation, with larger grain-sizes reflecting stronger NE trade winds and/or increased aridity (related to atmospheric subsidence). Reconstructions of precipitation in tropical Borneo (Meckler et al., Science, 2012), at the heart of the convective limb of the Hadley cell, show many similarities. In combination, the two data sets therefore likely reflect variations in strength of the Northern Hemisphere Hadley circulation. The records show clear precession-related cyclicity. In addition, the 100-kyr glacial-interglacial cycles are also apparent, with maxima in grain-size at Site 658 characterizing all glacial periods. Finally, shorter, millennial-scale events are evident at both locations. The presented data therefore reveal a persistent triumvirate of forcing factors, consisting of local insolation, high-latitude ice volume, and millennial-scale high-latitude cooling.

  17. Interleaved DC-DC Converter with Discrete Duty Cycle and Open Loop Control

    NASA Astrophysics Data System (ADS)

    Kroics, K.; Sokolovs, A.

    2016-08-01

    The authors present the control principle of the multiphase interleaved DC-DC converter that can be used to vastly reduce output current ripple of the converter. The control algorithm can be easily implemented by using microcontroller without current loop in each phase. The converter works in discontinuous conduction mode (DCM) but close to boundary conduction mode (BCM). The DC-DC converter with such a control algorithm is useful in applications that do not require precise current adjustment. The prototype of the converter has been built. The experimental results of the current ripple are presented in the paper.

  18. Autonomic regulation across phases of the menstrual cycle and sleep stages in women with premenstrual syndrome and healthy controls.

    PubMed

    de Zambotti, Massimiliano; Nicholas, Christian L; Colrain, Ian M; Trinder, John A; Baker, Fiona C

    2013-11-01

    To investigate the influence of menstrual cycle phase and the presence of severe premenstrual symptoms on cardiac autonomic control during sleep, we performed heart rate variability (HRV) analysis during stable non-rapid eye movement (NREM) and REM sleep in 12 women with severe premenstrual syndrome and 14 controls in the mid-follicular, mid-luteal, and late-luteal phases of the menstrual cycle. Heart rate was higher, along with lower high frequency (HF) power, reflecting reduced vagal activity, and a higher ratio of low frequency (LF) to high frequency power, reflecting a shift to sympathetic dominance, in REM sleep compared with NREM sleep in both groups of women. Both groups of women had higher heart rate during NREM and REM sleep in the luteal phase recordings compared with the mid-follicular phase. HF power in REM sleep was lowest in the mid-luteal phase, when progesterone was highest, in both groups of women. The mid-luteal phase reduction in HF power was also evident in NREM sleep in control women but not in women with PMS, suggesting some impact of premenstrual syndrome on autonomic responses to the hormone environment of the mid-luteal phase. In addition, mid-luteal phase progesterone levels correlated positively with HF power and negatively with LF/HF ratio in control women in NREM sleep and with the LF/HF ratio during REM sleep in both groups of women. Our findings suggest the involvement of female reproductive steroids in cardiac autonomic control during sleep in women with and without premenstrual syndrome.

  19. Open cycle ocean thermal energy conversion steam control and bypass system

    DOEpatents

    Wittig, J. Michael; Jennings, Stephen J.

    1980-01-01

    Two sets of hinged control doors for regulating motive steam flow from an evaporator to a condenser alternatively through a set of turbine blades in a steam bypass around the turbine blades. The evaporator has a toroidal shaped casing situated about the turbine's vertical axis of rotation and an outlet opening therein for discharging motive steam into an annular steam flow path defined between the turbine's radially inner and outer casing structures. The turbine blades extend across the steam flow path intermediate the evaporator and condenser. The first set of control doors is arranged to prevent steam access to the upstream side of the turbine blades and the second set of control doors acts as a bypass around the blades so as to maintain equilibrium between the evaporator and condenser during non-rotation of the turbine. The first set of control doors preferably extend, when closed, between the evaporator casing and the turbine's outer casing and, when open, extend away from the axis of rotation. The second set of control doors preferably constitute a portion of the turbine's outer casing downstream from the blades when closed and extend, when open, toward the axis of rotation. The first and second sets of control doors are normally held in the open and closed positions respectively by locking pins which may be retracted upon detecting an abnormal operating condition respectively to permit their closing and opening and provide steam flow from the evaporator to the condenser.

  20. Dosage-Sensitive Function of RETINOBLASTOMA RELATED and Convergent Epigenetic Control Are Required during the Arabidopsis Life Cycle

    PubMed Central

    Johnston, Amal J.; Kirioukhova, Olga; Barrell, Philippa J.; Rutten, Twan; Moore, James M.; Baskar, Ramamurthy; Grossniklaus, Ueli; Gruissem, Wilhelm

    2010-01-01

    The plant life cycle alternates between two distinct multi-cellular generations, the reduced gametophytes and the dominant sporophyte. Little is known about how generation-specific cell fate, differentiation, and development are controlled by the core regulators of the cell cycle. In Arabidopsis, RETINOBLASTOMA RELATED (RBR), an evolutionarily ancient cell cycle regulator, controls cell proliferation, differentiation, and regulation of a subset of Polycomb Repressive Complex 2 (PRC2) genes and METHYLTRANSFERASE 1 (MET1) in the male and female gametophytes, as well as cell fate establishment in the male gametophyte. Here we demonstrate that RBR is also essential for cell fate determination in the female gametophyte, as revealed by loss of cell-specific marker expression in all the gametophytic cells that lack RBR. Maintenance of genome integrity also requires RBR, because diploid plants heterozygous for rbr (rbr/RBR) produce an abnormal portion of triploid offspring, likely due to gametic genome duplication. While the sporophyte of the diploid mutant plants phenocopied wild type due to the haplosufficiency of RBR, genetic analysis of tetraploid plants triplex for rbr (rbr/rbr/rbr/RBR) revealed that RBR has a dosage-dependent pleiotropic effect on sporophytic development, trichome differentiation, and regulation of PRC2 subunit genes CURLY LEAF (CLF) and VERNALIZATION 2 (VRN2), and MET1 in leaves. There were, however, no obvious cell cycle and cell proliferation defects in these plant tissues, suggesting that a single functional RBR copy in tetraploids is capable of maintaining normal cell division but is not sufficient for distinct differentiation and developmental processes. Conversely, in leaves of mutants in sporophytic PRC2 subunits, trichome differentiation was also affected and expression of RBR and MET1 was reduced, providing evidence for a RBR-PRC2-MET1 regulatory feedback loop involved in sporophyte development. Together, dosage-sensitive RBR function and

  1. Processes Controlling the Seasonal Cycle of Arctic Aerosol Number and Size Distributions

    NASA Astrophysics Data System (ADS)

    Wentworth, G.; Croft, B.; Martin, R.; Leaitch, W. R.; Tunved, P.; Breider, T. J.; D'Andrea, S.; Pierce, J. R.; Murphy, J. G.; Kodros, J.; Abbatt, J.

    2015-12-01

    Measurements at high-Arctic sites show a strong seasonal cycle in aerosol number and size. The number of aerosols with diameters larger than 20 nm exhibits a maximum in late spring associated with a dominant accumulation mode, and a second maximum in the summer associated with a dominant Aitken mode. Seasonal-mean aerosol effective diameter ranges from about 160 nm in summer to 250 nm in winter. This study interprets these seasonal cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. We find improved agreement with in situ measurements (SMPS) of aerosol size at both Alert, Nunavut, and Mt. Zeppelin, Svalbard following model developments: 1) increase the efficiency of wet scavenging in the Arctic summer and 2) represent coagulation between interstitial aerosols and aerosols activated to form cloud droplets. Our simulations indicate that the dominant summer-time Aitken mode is associated with increased efficiency of wet removal, which limits the number of larger aerosols and promotes local new-aerosol formation. We also find an important role of interstitial coagulation in clouds in the Arctic, which limits the number of Aitken-mode aerosols in the non-summer seasons when direct wet removal of these aerosols is inefficient. The summertime Arctic atmosphere is particularly pristine and strongly influenced by natural regional emissions which have poorly understood climate impacts. Especially influenced are the climatic roles of atmospheric particles and clouds. Here we present evidence that ammonia (NH3) emissions from migratory-seabird guano (dung) are the primary contributor to summertime free ammonia levels recently measured in the Canadian Arctic atmosphere. These findings suggest that ammonia from seabird guano is a key factor contributing to bursts of new-particle formation, which are observed every summer in the near-surface atmosphere at Alert, Canada. Chemical transport model simulations show that these newly formed particles can grow by vapour

  2. SAS-4 Protein in Trypanosoma brucei Controls Life Cycle Transitions by Modulating the Length of the Flagellum Attachment Zone Filament.

    PubMed

    Hu, Huiqing; Zhou, Qing; Li, Ziyin

    2015-12-18

    The evolutionarily conserved centriole/basal body protein SAS-4 regulates centriole duplication in metazoa and basal body duplication in flagellated and ciliated organisms. Here, we report that the SAS-4 homolog in the flagellated protozoan Trypanosoma brucei, TbSAS-4, plays an unusual role in controlling life cycle transitions by regulating the length of the flagellum attachment zone (FAZ) filament, a specialized cytoskeletal structure required for flagellum adhesion and cell morphogenesis. TbSAS-4 is concentrated at the distal tip of the FAZ filament, and depletion of TbSAS-4 in the trypomastigote form disrupts the elongation of the new FAZ filament, generating cells with a shorter FAZ associated with a longer unattached flagellum and repositioned kinetoplast and basal body, reminiscent of epimastigote-like morphology. Further, we show that TbSAS-4 associates with six additional FAZ tip proteins, and depletion of TbSAS-4 disrupts the enrichment of these FAZ tip proteins at the new FAZ tip, suggesting a role of TbSAS-4 in maintaining the integrity of this FAZ tip protein complex. Together, these results uncover a novel function of TbSAS-4 in regulating the length of the FAZ filament to control basal body positioning and life cycle transitions in T. brucei.

  3. SAS-4 Protein in Trypanosoma brucei Controls Life Cycle Transitions by Modulating the Length of the Flagellum Attachment Zone Filament.

    PubMed

    Hu, Huiqing; Zhou, Qing; Li, Ziyin

    2015-12-18

    The evolutionarily conserved centriole/basal body protein SAS-4 regulates centriole duplication in metazoa and basal body duplication in flagellated and ciliated organisms. Here, we report that the SAS-4 homolog in the flagellated protozoan Trypanosoma brucei, TbSAS-4, plays an unusual role in controlling life cycle transitions by regulating the length of the flagellum attachment zone (FAZ) filament, a specialized cytoskeletal structure required for flagellum adhesion and cell morphogenesis. TbSAS-4 is concentrated at the distal tip of the FAZ filament, and depletion of TbSAS-4 in the trypomastigote form disrupts the elongation of the new FAZ filament, generating cells with a shorter FAZ associated with a longer unattached flagellum and repositioned kinetoplast and basal body, reminiscent of epimastigote-like morphology. Further, we show that TbSAS-4 associates with six additional FAZ tip proteins, and depletion of TbSAS-4 disrupts the enrichment of these FAZ tip proteins at the new FAZ tip, suggesting a role of TbSAS-4 in maintaining the integrity of this FAZ tip protein complex. Together, these results uncover a novel function of TbSAS-4 in regulating the length of the FAZ filament to control basal body positioning and life cycle transitions in T. brucei. PMID:26504079

  4. Genetic alterations in head and neck cancer: interactions among environmental carcinogens, cell cycle control, and host DNA repair.

    PubMed

    Fan, C Y

    2001-01-01

    Head and neck squamous cell carcinomas (HNSCC) arise as a consequence of cumulative genetic changes brought about by continued exposure to carcinogens associated with tobacco and alcohol use, influenced by viral agents such as human papillomaviruses, in a background of acquired or heritable genetic susceptibility. The presence of widespread genomic instability in HNSCC, such as cytogenetic aberrations, allelic imbalance/loss of heterozygosity, and microsatellite instability, suggests that there is an imperfection in the host DNA repair machinery. Genomic instability with progressive accumulation of detrimental genetic alterations appears to be dependent upon a circuitous interaction between the environmental genotoxic insults and the host DNA repair machinery, the functional integrity of which is governed by the proper cell cycle control and host DNA repair capacity. Thus, it can be hypothesized that continued exposure to environmental carcinogens (ie, longstanding history of smoking and drinking), loss of proper cell cycle control (eg, inactivation of p53 or p16 tumor suppressor genes or amplification of the proto-oncongene cyclin D1), and impaired DNA repair capacity (both inherited and acquired) are prerequisites in head and neck carcinogenesis.

  5. Magnetic Properties of Bermuda Rise Sediments Controlled by Glacial Cycles During the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Roud, S.

    2015-12-01

    Sediments from ODP site 1063 (Bermuda Rise, North Atlantic) contain a high-resolution record of geomagnetic field behavior during the Brunhes Chron. We present rock magnetic data of the upper 160 mcd (<900 ka) from hole 1063D that show magnetic properties vary in concert with glacial cycles. Magnetite appears to be the main magnetic carrier in the carbonate-dominated interglacial horizons, yet exhibits contrasting grain size distributions depending on the redox state of the horizons. Higher contributions of single domain magnetite exist above the present day sulfate reduction zone (ca. 44 mcd) with relatively higher multidomain magnetite components below that likely arise from the partial dissolution of SD magnetite in the deeper, anoxic horizons. Glacial horizons on the other hand, characterized by enhanced terrigenous deposition, show no evidence for diagenetic dissolution but do indicate the presence of authigenic greigite close to glacial maxima (acquisition of gyro-remanence, strong magnetostatic interactions and SD properties). Glacial horizons contain hematite (maxima in HIRM and S-Ratio consistent with a reddish hue) and exhibit higher ARM anisotropy and pronounced sedimentary fabrics. We infer that post depositional processes affected the magnetic grain size and mineralogy of Bermuda rise sediments deposited during the late Pleistocene. Hematite concentration is interpreted to reflect primary terrigenous input that is likely derived from the Canadian Maritime Provinces. A close correlation between HIRM and magnetic foliation suggests that changes in sediment composition (terrigenous vs. marine biogenic) were accompanied by changes in the depositional processes at the site.

  6. Orbital control of western North America atmospheric circulation and climate over two glacial cycles

    NASA Astrophysics Data System (ADS)

    Lachniet, Matthew S.; Denniston, Rhawn F.; Asmerom, Yemane; Polyak, Victor J.

    2014-05-01

    The now arid Great Basin of western North America hosted expansive late Quaternary pluvial lakes, yet the climate forcings that sustained large ice age hydrologic variations remain controversial. Here we present a 175,000 year oxygen isotope record from precisely-dated speleothems that documents a previously unrecognized and highly sensitive link between Great Basin climate and orbital forcing. Our data match the phasing and amplitudes of 65°N summer insolation, including the classic saw-tooth pattern of global ice volume and on-time terminations. Together with the observation of cold conditions during the marine isotope substage 5d glacial inception, our data document a strong precessional-scale Milankovitch forcing of southwestern paleoclimate. Because the expansion of pluvial lakes was associated with cold glacial conditions, the reappearance of large lakes in the Great Basin is unlikely until ca. 55,000 years into the future as climate remains in a mild non-glacial state over the next half eccentricity cycle.

  7. Manipulation and control of the estrous cycle in pasture-based dairy cows.

    PubMed

    Cavalieri, J; Hepworth, G; Fitzpatrick, L A; Shephard, R W; Macmillan, K L

    2006-01-01

    Treatments designed to synchronize luteolysis, preovulatory follicular development, and ovulation, and resynchronize estrus after a first AI have improved responses to synchronization treatments. Protocols based only on the use of PGF result in variable onset of estrus. Concentrations of progesterone prior to administering PGF have affected submission rates and fertility while administration of estradiol benzoate (EB) after inducing luteolysis has improved the synchrony of estrus and ovulation in some studies. In pasture-based dairy cows, GnRH-based protocols have generally resulted in one-third of both anestrous and cycling cows conceiving following synchronization of ovulation and timed AI. Protocols which use intravaginal progesterone releasing inserts (IVP4) are effective in inducing estrus in over 90% of treated dairy cows. Resynchronization of estrus after reinsertion of an IVP4 also improves the synchrony of returns to estrus, but pregnancy rates to the first AI have been reduced in some studies, and submission rates at a resynchronized estrus are less than at the first synchronized estrus. Administration of EB can be used to synchronize follicle wave emergence in resynchronized cows with intervals to new wave emergence comparable to that in cows synchronized for a first AI, but plasma concentrations of progesterone following treatment may be reduced. Synchronization of estrus and ovulation can be enhanced by administration of EB or GnRH during proestrus, but dose, timing and stage of follicular development at the time of treatment can affect outcomes. PMID:16278012

  8. Re-examination of sea lamprey control policies for the St. Marys River: Completion of an adaptive management cycle

    USGS Publications Warehouse

    Jones, Michael L.; Brenden, Travis O.; Irwin, Brian J.

    2015-01-01

    The St. Marys River (SMR) historically has been a major producer of sea lampreys (Petromyzon marinus) in the Laurentian Great Lakes. In the early 2000s, a decision analysis (DA) project was conducted to evaluate sea lamprey control policies for the SMR; this project suggested that an integrated policy of trapping, sterile male releases, and Bayluscide treatment was the most cost-effective policy. Further, it concluded that formal assessment of larval sea lamprey abundance and distribution in the SMR would be valuable for future evaluation of control strategies. We updated this earlier analysis, adding information from annual larval assessments conducted since 1999 and evaluating additional control policies. Bayluscide treatments continued to be critical for sea lamprey control, but high recruitment compensation minimized the effectiveness of trapping and sterile male release under current feasible ranges. Because Bayluscide control is costly, development of strategies to enhance trapping success remains a priority. This study illustrates benefits of an adaptive management cycle, wherein models inform decisions, are updated based on learning achieved from those decisions, and ultimately inform future decisions.

  9. Cycle scheduling for in vitro fertilization with oral contraceptive pills versus oral estradiol valerate: a randomized, controlled trial

    PubMed Central

    2013-01-01

    Background Both oral contraceptive pills (OCPs) and estradiol (E2) valerate have been used to schedule gonadotropin-releasing hormone (GnRH) antagonist in vitro fertilization (IVF) cycles and, consequently, laboratory activities. However, there are no studies comparing treatment outcomes directly between these two pretreatment methods. This randomized controlled trial was aimed at finding differences in ongoing pregnancy rates between GnRH antagonist IVF cycles scheduled with OCPs or E2 valerate. Methods Between January and May 2012, one hundred consecutive patients (nonobese, regularly cycling women 18–38 years with normal day 3 hormone levels and <3 previous IVF/ICSI attempts) undergoing IVF with the GnRH antagonist protocol were randomized to either the OCP or E2 pretreatment arms, with no restrictions such as blocking or stratification. Authors involved in data collection and analysis were blinded to group assignment. Fifty patients received OCP (30 μg ethinyl E2/150 μg levonorgestrel) for 12–16 days from day 1 or 2, and stimulation was started 5 days after stopping OCP. Similarly, 50 patients received 4 mg/day oral E2 valerate from day 20 for 5–12 days, until the day before starting stimulation. Results Pretreatment with OCP (mean±SD, 14.5±1.7 days) was significantly longer than with E2 (7.8±1.9 days). Stimulation and embryological characteristics were similar. Ongoing pregnancy rates (46.0% vs. 44.0%; risk difference, –2.0% [95% CI –21.2% to 17.3%]), as well as implantation (43.5% vs. 47.4%), clinical pregnancy (50.0% vs. 48.0%), clinical miscarriage (7.1% vs. 7.7%), and live birth (42.0% vs. 40.0%) rates were comparable between groups. Conclusions This is the first study to directly compare these two methods of cycle scheduling in GnRH antagonist cycles. Our results fail to show statistically significant differences in ongoing pregnancy rates between pretreatment with OCP and E2 for IVF with the GnRH antagonist protocol. Although the

  10. Methylmercury cycling in High Arctic wetland ponds: controls on sedimentary production.

    PubMed

    Lehnherr, Igor; St Louis, Vincent L; Kirk, Jane L

    2012-10-01

    Methylmercury (MeHg) is a potent neurotoxin that has been demonstrated to biomagnify in Arctic freshwater foodwebs to levels that may be of concern to Inuit peoples subsisting on freshwater fish, for example. The key process initiating the bioaccumulation and biomagnification of MeHg in foodwebs is the methylation of inorganic Hg(II) to form MeHg, and ultimately how much MeHg enters foodwebs is controlled by the production and availability of MeHg in a particular water body. We used isotopically enriched Hg stable isotope tracers in sediment core incubations to measure potential rates of Hg(II) methylation and investigate the controls on MeHg production in High Arctic wetland ponds in the Lake Hazen region of northern Ellesmere Island (Nunavut, Canada). We show here that MeHg concentrations in sediments are primarily controlled by the sediment methylation potential and the quantity of Hg(II) available for methylation, but not by sediment demethylation potential. Furthermore, MeHg concentrations in pond waters are controlled by MeHg production in sediments, overall anaerobic microbial activity, and photodemethylation in the water column.

  11. Life cycle of Puccinia crupinae, a candidate fungal biological control agent for Crupina vulgaris

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crupina vulgaris (Common crupina, Asteraceae) is an introduced weed pest in the western United States. An isolate of the rust fungus Puccinia crupinae from the Greece is currently under evaluation as a candidate for biological control of C. crupina in a Biosafety Level 3 (BL-3) containment greenhou...

  12. Plants control the seasonal dynamics of microbial N cycling in a beech forest soil by belowground C allocation.

    PubMed

    Kaiser, Christina; Fuchslueger, Lucia; Koranda, Marianne; Gorfer, Markus; Stange, Claus F; Kitzler, Barbara; Rasche, Frank; Strauss, Joseph; Sessitsch, Angela; Zechmeister-Boltenstern, Sophie; Richter, Andreas

    2011-05-01

    Soil microbes in temperate forest ecosystems are able to cycle several hundreds of kilograms of N per hectare per year and are therefore of paramount importance for N retention. Belowground C allocation by trees is an important driver of seasonal microbial dynamics and may thus directly affect N transformation processes over the course of the year. Our study aimed at unraveling plant controls on soil N cycling in a temperate beech forest at a high temporal resolution over a time period of two years, by investigating the effects of tree girdling on microbial N turnover. In both years of the experiment, we discovered (1) a summer N mineralization phase (between July and August) and (2) a winter N immobilization phase (November-February). The summer mineralization phase was characterized by a high N mineralization activity, low microbial N uptake, and a subsequent high N availability in the soil. During the autumn/winter N immobilization phase, gross N mineralization rates were low, and microbial N uptake exceeded microbial N mineralization, which led to high levels of N in the microbial biomass and low N availability in the soil. The observed immobilization phase during the winter may play a crucial role for ecosystem functioning, since it could protect dissolved N that is produced by autumn litter degradation from being lost from the ecosystem during the phase when plants are mostly inactive. The difference between microbial biomass N levels in winter and spring equals 38 kg N/ha and may thus account for almost one-third of the annual plant N demand. Tree girdling strongly affected annual N cycling: the winter N immobilization phase disappeared in girdled plots (microbial N uptake and microbial biomass N were significantly reduced, while the amount of available N in the soil solution was enhanced). This was correlated to a reduced fungal abundance in autumn in girdled plots. By releasing recently fixed photosynthates to the soil, plants may thus actively control the

  13. Role of the ovarian cycle on neural cardiovascular control in sleep-deprived women

    PubMed Central

    Yang, Huan; Durocher, John J.; Larson, Robert A.

    2014-01-01

    The midluteal (ML) phase of the ovarian cycle is often sympathoexcitatory compared with the early follicular (EF) phase. We recently reported that 24-h total sleep deprivation (TSD) augmented cardiovascular reactivity in both men and women, but that sex differences existed in resting muscle sympathetic nerve activity (MSNA) responses to TSD. In the present study, we hypothesized increased resting MSNA and augmented cardiovascular reactivity to acute laboratory stressors during the ML phase in sleep-deprived women. Heart rate (HR), mean arterial pressure (MAP), forearm vascular conductance (FVC), and MSNA were measured in 14 eumenorrheic women (age, 20 ± 1 yr) during 10 min supine rest, 5 min mental stress (MS) trial, and 2 min cold pressor test (CPT) trial. Subjects were tested twice after TSD: once during EF phase and once during ML phase (randomized, crossover design). Estradiol (29 ± 2 vs. 63 ± 8 pg/ml, P = 0.001) and progesterone (1.6 ± 0.2 vs. 4.4 ± 0.7 ng/ml, P = 0.002) were elevated during the ML phase. Resting supine MAP (75 ± 2 vs. 72 ± 1 mmHg, P = 0.042) was lower during the ML phase. In contrast, resting supine HR, MSNA, and FVC were not significantly different between EF and ML phases. MAP, HR and FVC reactivity to MS were not statistically different between the EF and ML phases. Similarly, MAP and HR reactivity to CPT were not different between the ovarian phases. Contrary to our original hypothesis, the ML phase was not associated with sympathoexcitation or exaggerated cardiovascular reactivity in sleep-deprived premenopausal women. However, our data reveal elevated resting blood pressure during the EF phase in sleep-deprived women. PMID:25539931

  14. Role of the ovarian cycle on neural cardiovascular control in sleep-deprived women.

    PubMed

    Yang, Huan; Durocher, John J; Larson, Robert A; Carter, Jason R

    2015-02-15

    The midluteal (ML) phase of the ovarian cycle is often sympathoexcitatory compared with the early follicular (EF) phase. We recently reported that 24-h total sleep deprivation (TSD) augmented cardiovascular reactivity in both men and women, but that sex differences existed in resting muscle sympathetic nerve activity (MSNA) responses to TSD. In the present study, we hypothesized increased resting MSNA and augmented cardiovascular reactivity to acute laboratory stressors during the ML phase in sleep-deprived women. Heart rate (HR), mean arterial pressure (MAP), forearm vascular conductance (FVC), and MSNA were measured in 14 eumenorrheic women (age, 20 ± 1 yr) during 10 min supine rest, 5 min mental stress (MS) trial, and 2 min cold pressor test (CPT) trial. Subjects were tested twice after TSD: once during EF phase and once during ML phase (randomized, crossover design). Estradiol (29 ± 2 vs. 63 ± 8 pg/ml, P = 0.001) and progesterone (1.6 ± 0.2 vs. 4.4 ± 0.7 ng/ml, P = 0.002) were elevated during the ML phase. Resting supine MAP (75 ± 2 vs. 72 ± 1 mmHg, P = 0.042) was lower during the ML phase. In contrast, resting supine HR, MSNA, and FVC were not significantly different between EF and ML phases. MAP, HR and FVC reactivity to MS were not statistically different between the EF and ML phases. Similarly, MAP and HR reactivity to CPT were not different between the ovarian phases. Contrary to our original hypothesis, the ML phase was not associated with sympathoexcitation or exaggerated cardiovascular reactivity in sleep-deprived premenopausal women. However, our data reveal elevated resting blood pressure during the EF phase in sleep-deprived women. PMID:25539931

  15. Plasma surrounding the global heliosphere at large distances controlled by the solar cycle

    NASA Astrophysics Data System (ADS)

    Dialynas, Konstantinos; Krimigis, Stamatios; Mitchell, Donald; Decker, Robert; Roelof, Edmond

    2016-04-01

    The past decade can be characterized by a series of key, groundbreaking remote energetic neutral atom (ENA) images (INCA, IBEX) and in-situ ion (Voyager 1 & 2) observations concerning the characteristics and interactions of the heliosphere with the Local Interstellar Medium (LISM). Voyagers 1 and 2 (V1, V2) discovered the reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x108 km), respectively. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images contain a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). The success of any future mission with dedicated ENA detectors (e.g. the IMAP mission), highly depends on the antecedent understanding of the details of the plasma processes in the Heliosphere as revealed by remote sensing of the plasma environment characteristics. Therefore, we address here one of the remaining and most important questions: "Where do the 5-55 keV ENAs that INCA measures come from?". We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ~30-55 keV. ENA intensities decrease during the declining phase of SC23 by ~x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS

  16. Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

    NASA Astrophysics Data System (ADS)

    Joshi, Ramesh; Singh, Manoj; Jadav, H. M.; Misra, Kishor; Kulkarni, S. V.; ICRH-RF Group

    2010-02-01

    Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twise, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in

  17. Controlled polar asymmetry of few-cycle and intense mid-infrared pulses

    NASA Astrophysics Data System (ADS)

    Schmidt, Christian; Bühler, Johannes; Mayer, Bernhard; Pashkin, Alexej; Leitenstorfer, Alfred; Seletskiy, Denis V.

    2016-05-01

    We demonstrate synthesis of ultrabroadband and phase-locked two-color transients in the multi-terahertz frequency range with amplitudes exceeding 13 MV cm-1. Subcycle polar asymmetry of the electric field is adjusted by changing the relative phase between superposed fundamental and second harmonic components. The resultant broken symmetry of the field profile is directly resolved via electro-optic sampling. Access to such waveforms provides a direct route for control of low-energy degrees of freedom in condensed matter as well as non-perturbative light-matter interactions under highest non-resonant electric bias.

  18. Development of the ANL plant dynamics code and control strategies for the supercritical carbon dioxide Brayton cycle and code validation with data from the Sandia small-scale supercritical carbon dioxide Brayton cycle test loop.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.

    2011-11-07

    Significant progress has been made in the ongoing development of the Argonne National Laboratory (ANL) Plant Dynamics Code (PDC), the ongoing investigation and development of control strategies, and the analysis of system transient behavior for supercritical carbon dioxide (S-CO{sub 2}) Brayton cycles. Several code modifications have been introduced during FY2011 to extend the range of applicability of the PDC and to improve its calculational stability and speed. A new and innovative approach was developed to couple the Plant Dynamics Code for S-CO{sub 2} cycle calculations with SAS4A/SASSYS-1 Liquid Metal Reactor Code System calculations for the transient system level behavior on the reactor side of a Sodium-Cooled Fast Reactor (SFR) or Lead-Cooled Fast Reactor (LFR). The new code system allows use of the full capabilities of both codes such that whole-plant transients can now be simulated without additional user interaction. Several other code modifications, including the introduction of compressor surge control, a new approach for determining the solution time step for efficient computational speed, an updated treatment of S-CO{sub 2} cycle flow mergers and splits, a modified enthalpy equation to improve the treatment of negative flow, and a revised solution of the reactor heat exchanger (RHX) equations coupling the S-CO{sub 2} cycle to the reactor, were introduced to the PDC in FY2011. All of these modifications have improved the code computational stability and computational speed, while not significantly affecting the results of transient calculations. The improved PDC was used to continue the investigation of S-CO{sub 2} cycle control and transient behavior. The coupled PDC-SAS4A/SASSYS-1 code capability was used to study the dynamic characteristics of a S-CO{sub 2} cycle coupled to a SFR plant. Cycle control was investigated in terms of the ability of the cycle to respond to a linear reduction in the electrical grid demand from 100% to 0% at a rate of 5

  19. An Oct4-pRb axis, controlled by MiR-335, integrates stem cell self-renewal and cell cycle control.

    PubMed

    Schoeftner, Stefan; Scarola, Michele; Comisso, Elisa; Schneider, Claudio; Benetti, Roberta

    2013-04-01

    The pluripotency of mouse embryonic stem cells (mESCs) is controlled by a network of transcription factors, mi-RNAs, and signaling pathways. Here, we present a new regulatory circuit that connects miR-335, Oct4, and the Retinoblastoma pathway to control mESC self-renewal and differentiation. Oct4 drives the expression of Nipp1 and Ccnf that inhibit the activity of the protein phosphatase 1 (PP1) complex to establish hyperphosphorylation of the retinoblastoma protein 1 (pRb) as a hallmark feature of self-renewing mESCs. The Oct4-Nipp1/Ccnf-PP1-pRb axis promoting mESC self-renewal is under control of miR-335 that regulates Oct4 and Rb expression. During mESC differentiation, miR-335 upregulation co-operates with the transcriptional repression of Oct4 to facilitate the collapse of the Oct4-Nipp1/Ccnf-PP1-pRb axis, pRb dephosphorylation, the exit from self-renewal, and the establishment of a pRb-regulated cell cycle program. Our results introduce Oct4-dependent control of the Rb pathway as novel regulatory circuit controlling mESC self-renewal and differentiation.

  20. Visceral Leishmaniasis on the Indian Subcontinent: Modelling the Dynamic Relationship between Vector Control Schemes and Vector Life Cycles

    PubMed Central

    2016-01-01

    Background Visceral leishmaniasis (VL) is a disease caused by two known vector-borne parasite species (Leishmania donovani, L. infantum), transmitted to man by phlebotomine sand flies (species: Phlebotomus and Lutzomyia), resulting in ≈50,000 human fatalities annually, ≈67% occurring on the Indian subcontinent. Indoor residual spraying is the current method of sand fly control in India, but alternative means of vector control, such as the treatment of livestock with systemic insecticide-based drugs, are being evaluated. We describe an individual-based, stochastic, life-stage-structured model that represents a sand fly vector population within a village in India and simulates the effects of vector control via fipronil-based drugs orally administered to cattle, which target both blood-feeding adults and larvae that feed on host feces. Principle findings Simulation results indicated efficacy of fipronil-based control schemes in reducing sand fly abundance depended on timing of drug applications relative to seasonality of the sand fly life cycle. Taking into account cost-effectiveness and logistical feasibility, two of the most efficacious treatment schemes reduced population peaks occurring from April through August by ≈90% (applications 3 times per year at 2-month intervals initiated in March) and >95% (applications 6 times per year at 2-month intervals initiated in January) relative to no control, with the cumulative number of sand fly days occurring April-August reduced by ≈83% and ≈97%, respectively, and more specifically during the summer months of peak human exposure (June-August) by ≈85% and ≈97%, respectively. Conclusions Our model should prove useful in a priori evaluation of the efficacy of fipronil-based drugs in controlling leishmaniasis on the Indian subcontinent and beyond. PMID:27537774

  1. Micro-RNA-31 controls hair cycle-associated changes in gene expression programs of the skin and hair follicle.

    PubMed

    Mardaryev, Andrei N; Ahmed, Mohammed I; Vlahov, Nikola V; Fessing, Michael Y; Gill, Jason H; Sharov, Andrey A; Botchkareva, Natalia V

    2010-10-01

    The hair follicle is a cyclic biological system that progresses through stages of growth, regression, and quiescence, which involves dynamic changes in a program of gene regulation. Micro-RNAs (miRNAs) are critically important for the control of gene expression and silencing. Here, we show that global miRNA expression in the skin markedly changes during distinct stages of the hair cycle in mice. Furthermore, we show that expression of miR-31 markedly increases during anagen and decreases during catagen and telogen. Administration of antisense miR-31 inhibitor into mouse skin during the early- and midanagen phases of the hair cycle results in accelerated anagen development, and altered differentiation of hair matrix keratinocytes and hair shaft formation. Microarray, qRT-PCR and Western blot analyses revealed that miR-31 negatively regulates expression of Fgf10, the components of Wnt and BMP signaling pathways Sclerostin and BAMBI, and Dlx3 transcription factor, as well as selected keratin genes, both in vitro and in vivo. Using luciferase reporter assay, we show that Krt16, Krt17, Dlx3, and Fgf10 serve as direct miR-31 targets. Thus, by targeting a number of growth regulatory molecules and cytoskeletal proteins, miR-31 is involved in establishing an optimal balance of gene expression in the hair follicle required for its proper growth and hair fiber formation. PMID:20522784

  2. Thiram and dimethyldithiocarbamic acid interconversion in Saccharomyces cerevisiae: a possible metabolic pathway under the control of the glutathione redox cycle.

    PubMed

    Elskens, M T; Penninckx, M J

    1997-07-01

    A rapid decrease of intracellular glutathione (GSH) was observed when exponentially growing cells of Saccharomyces cerevisiae were treated with sublethal concentrations of either dimethyldithiocarbamic acid or thiram [bis(dimethylthiocarbamoyl) disulfide]. The underlying mechanism of this effect possibly involves the intracellular oxidation of dimethyldithiocarbamate anions to thiram, which in turn oxidizes GSH. Overall, a linear relationship was found between thiram concentrations up to 21 microM and production of oxidized GSH (GSSG). Cytochrome c can serve as the final electron acceptor for dimethyldithiocarbamate reoxidation, and it was demonstrated in vitro that NADPH handles the final electron transfer from GSSG to the fungicide by glutathione reductase. These cycling reactions induce transient alterations in the intracellular redox state of several electron carriers and interfere with the respiration of the yeast. Thiram and dimethyldithiocarbamic acid also inactivate yeast glutathione reductase when the fungicide is present within the cells as the disulfide. Hence, whenever the GSH regeneration rate falls below its oxidation rate, the GSH:GSSG molar ratio drops from 45 to 1. Inhibition of glutathione reductase may be responsible for the saturation kinetics observed in rates of thiram elimination and uptake by the yeast. The data suggest also a leading role for the GSH redox cycle in the control of thiram and dimethyldithiocarbamic acid fungitoxicity. Possible pathways for the handling of thiram and dimethyldithiocarbamic acid by yeast are considered with respect to the physiological status, the GSH content, and the activity of glutathione reductase of the cells.

  3. Chapter 2: hypothalamic neural systems controlling the female reproductive life cycle gonadotropin-releasing hormone, glutamate, and GABA.

    PubMed

    Maffucci, Jacqueline A; Gore, Andrea C

    2009-01-01

    The hypothalamic-pituitary-gonadal (HPG) axis undergoes a number of changes throughout the reproductive life cycle that are responsible for the development, puberty, adulthood, and senescence of reproductive systems. This natural progression is dictated by the neural network controlling the hypothalamus including the cells that synthesize and release gonadotropin-releasing hormone (GnRH) and their regulatory neurotransmitters. Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters in the central nervous system, and as such contribute a great deal to modulating this axis throughout the lifetime via their actions on receptors in the hypothalamus, both directly on GnRH neurons as well as indirectly through other hypothalamic neural networks. Interactions among GnRH neurons, glutamate, and GABA, including the regulation of GnRH gene and protein expression, hormone release, and modulation by estrogen, are critical to age-appropriate changes in reproductive function. Here, we present evidence for the modulation of GnRH neurosecretory cells by the balance of glutamate and GABA in the hypothalamus, and the functional consequences of these interactions on reproductive physiology across the life cycle.

  4. Micro-RNA-31 controls hair cycle-associated changes in gene expression programs of the skin and hair follicle.

    PubMed

    Mardaryev, Andrei N; Ahmed, Mohammed I; Vlahov, Nikola V; Fessing, Michael Y; Gill, Jason H; Sharov, Andrey A; Botchkareva, Natalia V

    2010-10-01

    The hair follicle is a cyclic biological system that progresses through stages of growth, regression, and quiescence, which involves dynamic changes in a program of gene regulation. Micro-RNAs (miRNAs) are critically important for the control of gene expression and silencing. Here, we show that global miRNA expression in the skin markedly changes during distinct stages of the hair cycle in mice. Furthermore, we show that expression of miR-31 markedly increases during anagen and decreases during catagen and telogen. Administration of antisense miR-31 inhibitor into mouse skin during the early- and midanagen phases of the hair cycle results in accelerated anagen development, and altered differentiation of hair matrix keratinocytes and hair shaft formation. Microarray, qRT-PCR and Western blot analyses revealed that miR-31 negatively regulates expression of Fgf10, the components of Wnt and BMP signaling pathways Sclerostin and BAMBI, and Dlx3 transcription factor, as well as selected keratin genes, both in vitro and in vivo. Using luciferase reporter assay, we show that Krt16, Krt17, Dlx3, and Fgf10 serve as direct miR-31 targets. Thus, by targeting a number of growth regulatory molecules and cytoskeletal proteins, miR-31 is involved in establishing an optimal balance of gene expression in the hair follicle required for its proper growth and hair fiber formation.

  5. The pyruvate-tricarboxylic acid cycle node: a focal point of virulence control in the enteric pathogen Yersinia pseudotuberculosis.

    PubMed

    Bücker, René; Heroven, Ann Kathrin; Becker, Judith; Dersch, Petra; Wittmann, Christoph

    2014-10-24

    Despite our increasing knowledge of the specific pathogenicity factors in bacteria, the contribution of metabolic processes to virulence is largely unknown. Here, we elucidate a tight connection between pathogenicity and core metabolism in the enteric pathogen Yersinia pseudotuberculosis by integrated transcriptome and [(13)C]fluxome analysis of the wild type and virulence-regulator mutants. During aerobic growth on glucose, Y. pseudotuberculosis reveals an unusual flux distribution with a high level of secreted pyruvate. The absence of the transcriptional and post-transcriptional regulators RovA, CsrA, and Crp strongly perturbs the fluxes of carbon core metabolism at the level of pyruvate metabolism and the tricarboxylic acid (TCA) cycle, and these perturbations are accompanied by transcriptional changes in the corresponding enzymes. Knock-outs of regulators of this metabolic branch point and of its central enzyme, pyruvate kinase (ΔpykF), result in mutants with significantly reduced virulence in an oral mouse infection model. In summary, our work identifies the pyruvate-TCA cycle node as a focal point for controlling the host colonization and virulence of Yersinia.

  6. APC/CCdh1 controls CtIP stability during the cell cycle and in response to DNA damage

    PubMed Central

    Lafranchi, Lorenzo; de Boer, Harmen R; de Vries, Elisabeth GE; Ong, Shao-En; Sartori, Alessandro A; van Vugt, Marcel ATM

    2014-01-01

    Human cells have evolved elaborate mechanisms for responding to DNA damage to maintain genome stability and prevent carcinogenesis. For instance, the cell cycle can be arrested at different stages to allow time for DNA repair. The APC/CCdh1 ubiquitin ligase mainly regulates mitotic exit but is also implicated in the DNA damage-induced G2 arrest. However, it is currently unknown whether APC/CCdh1 also contributes to DNA repair. Here, we show that Cdh1 depletion causes increased levels of genomic instability and enhanced sensitivity to DNA-damaging agents. Using an integrated proteomics and bioinformatics approach, we identify CtIP, a DNA-end resection factor, as a novel APC/CCdh1 target. CtIP interacts with Cdh1 through a conserved KEN box, mutation of which impedes ubiquitylation and downregulation of CtIP both during G1 and after DNA damage in G2. Finally, we find that abrogating the CtIP–Cdh1 interaction results in delayed CtIP clearance from DNA damage foci, increased DNA-end resection, and reduced homologous recombination efficiency. Combined, our results highlight the impact of APC/CCdh1 on the maintenance of genome integrity and show that this is, at least partially, achieved by controlling CtIP stability in a cell cycle- and DNA damage-dependent manner. PMID:25349192

  7. Thiram and dimethyldithiocarbamic acid interconversion in Saccharomyces cerevisiae: a possible metabolic pathway under the control of the glutathione redox cycle.

    PubMed Central

    Elskens, M T; Penninckx, M J

    1997-01-01

    A rapid decrease of intracellular glutathione (GSH) was observed when exponentially growing cells of Saccharomyces cerevisiae were treated with sublethal concentrations of either dimethyldithiocarbamic acid or thiram [bis(dimethylthiocarbamoyl) disulfide]. The underlying mechanism of this effect possibly involves the intracellular oxidation of dimethyldithiocarbamate anions to thiram, which in turn oxidizes GSH. Overall, a linear relationship was found between thiram concentrations up to 21 microM and production of oxidized GSH (GSSG). Cytochrome c can serve as the final electron acceptor for dimethyldithiocarbamate reoxidation, and it was demonstrated in vitro that NADPH handles the final electron transfer from GSSG to the fungicide by glutathione reductase. These cycling reactions induce transient alterations in the intracellular redox state of several electron carriers and interfere with the respiration of the yeast. Thiram and dimethyldithiocarbamic acid also inactivate yeast glutathione reductase when the fungicide is present within the cells as the disulfide. Hence, whenever the GSH regeneration rate falls below its oxidation rate, the GSH:GSSG molar ratio drops from 45 to 1. Inhibition of glutathione reductase may be responsible for the saturation kinetics observed in rates of thiram elimination and uptake by the yeast. The data suggest also a leading role for the GSH redox cycle in the control of thiram and dimethyldithiocarbamic acid fungitoxicity. Possible pathways for the handling of thiram and dimethyldithiocarbamic acid by yeast are considered with respect to the physiological status, the GSH content, and the activity of glutathione reductase of the cells. PMID:9212433

  8. Biogeochemical and hydrologic processes controlling mercury cycling in Great Salt Lake, Utah

    NASA Astrophysics Data System (ADS)

    Naftz, D.; Kenney, T.; Angeroth, C.; Waddell, B.; Darnall, N.; Perschon, C.; Johnson, W. P.

    2006-12-01

    Great Salt Lake (GSL), in the Western United States, is a terminal lake with a highly variable surface area that can exceed 5,100 km2. The open water and adjacent wetlands of the GSL ecosystem support millions of migratory waterfowl and shorebirds from throughout the Western Hemisphere, as well as a brine shrimp industry with annual revenues exceeding 70 million dollars. Despite the ecologic and economic significance of GSL, little is known about the biogeochemical cycling of mercury (Hg) and no water-quality standards currently exist for this system. Whole water samples collected since 2000 were determined to contain elevated concentrations of total Hg (100 ng/L) and methyl Hg (33 ng/L). The elevated levels of methyl Hg are likely the result of high rates of SO4 reduction and associated Hg methylation in persistently anoxic areas of the lake at depths greater than 6.5 m below the water surface. Hydroacoustic equipment deployed in this anoxic layer indicates a "conveyor belt" flow system that can distribute methyl Hg in a predominantly southerly direction throughout the southern half of GSL (fig. 1, URL: http://users.o2wire.com/dnaftz/Dave/AGU-abs-figs- AUG06.pdf). Periodic and sustained wind events on GSL may result in transport of the methyl Hg-rich anoxic water and bottom sediments into the oxic and biologically active regions. Sediment traps positioned above the anoxic brine interface have captured up to 6 mm of bottom sediment during cumulative wind-driven resuspension events (fig. 2, URL:http://users.o2wire.com/dnaftz/Dave/AGU-abs-figs-AUG06.pdf). Vertical velocity data collected with hydroacoustic equipment indicates upward flow > 1.5 cm/sec during transient wind events (fig. 3, URL:http://users.o2wire.com/dnaftz/Dave/AGU-abs-figs-AUG06.pdf). Transport of methyl Hg into the oxic regions of GSL is supported by biota samples. The median Hg concentration (wet weight) in brine shrimp increased seasonally from the spring to fall time period and is likely a

  9. LUMOR: an app for standardized control and monitoring of a porcine lung and its nutrient cycle.

    PubMed

    Lenz, Gregor; Frohner, Matthias; Sauermann, Stefan; Forjan, Mathias

    2014-01-01

    The outcome of the EU-funded project ElBik has been the lung simulator 'iLung', which imitates an actively breathing human lung with a porcine lung. In order to keep the explanted lung in a nearly physiological state during transportation from the slaughterhouse to the ventilation laboratory the tissue needs to be nourished and temperature controlled. The Project AlveoPic designs a mobile transport vehicle implementing an ISO/IEEE 11073-20601 compliant communication interface for the exchange of the physical parameters, alert messages and setpoint-values. An appropriate 11073 domain information model is designed and limitations of the defined services and attributes are identified. For monitoring purposes the Android App LUMOR is implemented providing a user with an easy-to-handle GUI. It was found, that alert capabilities and remote set features are not well supported in ISO/IEEE 11073-20601 at the moment and possible workarounds are discussed. PMID:24825688

  10. Dehumidification Performance of Hybrid Type Humidity Control System Coupling a Desiccant Rotor in a Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Horibe, Akihiko; Takaki, Sadao; Inaba, Hideo; Haruki, Naoto

    Desiccant air-conditioning system is a promising technology because the exhaust heat can be effectively used in the future. We have reported the proposed system that combines a desiccant rotor with a vapor compression refrigerator. The confirmation experiment of stability and the performance was conducted with the experimental prototype. The result showed that it had the performance that was necessary for dehumidification driving in the summer and the humidification driving in the winter. In this report, we examined the influence on humidity controlling performance of the processing air temperature and humidity. As a result, we got high dehumidification efficiency and clarified the dehumidification characteristic in dehumidification driving in the summer. Dehumidification efficiency about 4.0 kg/kWh and COP of the system about 2.0 in summer driving mode were obtained.

  11. p63/p73 in the control of cell cycle and cell death

    SciTech Connect

    Allocati, N.; Di Ilio, C.; De Laurenzi, V.

    2012-07-01

    The p53 family apparently derives from a common ancient ancestor that dates back over a billion years, whose function was protecting the germ line from DNA damage. p63 and p73 would maintain this function through evolution while acquiring novel roles in controlling proliferation and differentiation of various tissues. p53 on the other hand would appear in early vertebrates to protect somatic cells from DNA damage with similar mechanism used by its siblings to protect germ line cells . For the predominant role played by p53 mutations in cancer this was the first family member to be identified and soon became one of the most studied genes. Its siblings were identified almost 20 years later and interestingly enough their ancestral function as guardians of the germ-line was one of the last to be identified. In this review we shortly summarize the current knowledge on the structure and function of p63 and p73.

  12. Carbon cycle. Sunlight controls water column processing of carbon in arctic fresh waters.

    PubMed

    Cory, Rose M; Ward, Collin P; Crump, Byron C; Kling, George W

    2014-08-22

    Carbon in thawing permafrost soils may have global impacts on climate change; however, the factors that control its processing and fate are poorly understood. The dominant fate of dissolved organic carbon (DOC) released from soils to inland waters is either complete oxidation to CO2 or partial oxidation and river export to oceans. Although both processes are most often attributed to bacterial respiration, we found that photochemical oxidation exceeds rates of respiration and accounts for 70 to 95% of total DOC processed in the water column of arctic lakes and rivers. At the basin scale, photochemical processing of DOC is about one-third of the total CO2 released from surface waters and is thus an important component of the arctic carbon budget.

  13. An introduction to the nitrogen dynamics in controlled systems workshop. Life support and nitrogen: NASA's interest in nitrogen cycling

    NASA Technical Reports Server (NTRS)

    MacElroy, R. D.; Smernoff, D. T.

    1996-01-01

    A Workshop on "Nitrogen Dynamics in Controlled Systems" was held September 26-28, 1995 at the Lawrence Berkeley National Laboratory. The meetings were sponsored by the NASA Advanced Life Support program and the Lawrence Berkeley National Laboratory, and hosted by Prof. Lester Packer of the University of California at Berkeley, and of the Lawrence Berkeley National Laboratory. The Workshop participants were asked to: 1. summarize current knowledge on the cycling of nitrogen in closed systems; 2. identify the needs that closed systems may have for specific forms of nitrogen; 3. identify possible ways of generating and maintaining (or avoiding) specific forms and concentrations of nitrogen; 4. compare biological and physical/chemical methods of transforming nitrogen.

  14. A Life-Cycle Cost Estimating Methodology for NASA-Developed Air Traffic Control Decision Support Tools

    NASA Technical Reports Server (NTRS)

    Wang, Jianzhong Jay; Datta, Koushik; Landis, Michael R. (Technical Monitor)

    2002-01-01

    This paper describes the development of a life-cycle cost (LCC) estimating methodology for air traffic control Decision Support Tools (DSTs) under development by the National Aeronautics and Space Administration (NASA), using a combination of parametric, analogy, and expert opinion methods. There is no one standard methodology and technique that is used by NASA or by the Federal Aviation Administration (FAA) for LCC estimation of prospective Decision Support Tools. Some of the frequently used methodologies include bottom-up, analogy, top-down, parametric, expert judgement, and Parkinson's Law. The developed LCC estimating methodology can be visualized as a three-dimensional matrix where the three axes represent coverage, estimation, and timing. This paper focuses on the three characteristics of this methodology that correspond to the three axes.

  15. Comparative urban drive cycle simulations of light-duty hybrid vehicles with gasoline or diesel engines and emissions controls

    SciTech Connect

    Gao, Zhiming; Daw, C Stuart; Smith, David E

    2013-01-01

    Electric hybridization is a very effective approach for reducing fuel consumption in light-duty vehicles. Lean combustion engines (including diesels) have also been shown to be significantly more fuel efficient than stoichiometric gasoline engines. Ideally, the combination of these two technologies would result in even more fuel efficient vehicles. However, one major barrier to achieving this goal is the implementation of lean-exhaust aftertreatment that can meet increasingly stringent emissions regulations without heavily penalizing fuel efficiency. We summarize results from comparative simulations of hybrid electric vehicles with either stoichiometric gasoline or diesel engines that include state-of-the-art aftertreatment emissions controls for both stoichiometric and lean exhaust. Fuel consumption and emissions for comparable gasoline and diesel light-duty hybrid electric vehicles were compared over a standard urban drive cycle and potential benefits for utilizing diesel hybrids were identified. Technical barriers and opportunities for improving the efficiency of diesel hybrids were identified.

  16. The cell cycle inhibitor p21 controls T-cell proliferation and sex-linked lupus development.

    PubMed

    Balomenos, D; Martín-Caballero, J; García, M I; Prieto, I; Flores, J M; Serrano, M; Martínez-A, C

    2000-02-01

    Here we show that the cell-cycle regulator p21 is involved in immune system function. T lymphocytes from p21-/- mice exhibit significant proliferative advantage over wild-type cells following prolonged stimulation, but not after primary activation. Consistent with this, p21-deficient mice accumulate abnormal amounts of CD4+ memory cells, and develop loss of tolerance towards nuclear antigens. Similar to human lupus, female p21-deficient mice develop antibodies against dsDNA, lymphadenopathy, and glomerulonephritis, leading to decreased viability. These data demonstrate a specialized role for p21 in the control of T-cell proliferation, tolerance to nuclear antigens, and female-prone lupus. These findings could be the basis for new therapeutic approaches to lupus.

  17. Difference of Body Compositional Changes According to the Presence of Weight Cycling in a Community-based Weight Control Program

    PubMed Central

    Yoo, Hyun-Jeong; Kim, Bom-Taeck; Park, Yong-Woo; Park, Kyung-Hee; Kim, Chan-Won

    2010-01-01

    Many obese people who try to control body weight experience weight cycling (WC). The present study evaluated the importance of WC in a community-based obesity intervention program. We analyzed the data of 109 Korean participants (86% women) among 177 subjects who had completed a 12-week intervention program at two public health centers in Korea from April to December, 2007. Completion of a self-administrated questionnaire at baseline was used to obtain anthropometric measurements, and laboratory testing was done before and after the program. Differences in body composition change and obesity-related life style between the two groups were compared with respect to WC and non-weight cycling (NWC). After 12 weeks, both groups showed reductions in weight, waist circumference, and body mass index. The group differences were not significant. However, significant differences were evident for the WC group compared to the NWC group in fat percent mass (WC vs. NWC, -3.49±2.31% vs. -4.65±2.59%, P=0.01), fat free mass (WC vs. NWC, -0.95±1.37 kg vs. -0.38±1.05 kg, P=0.01), and total cholesterol (WC vs. NWC, -3.32±14.63 vs. -16.54±32.39, P=0.005). In conducting a community-based weight control program that predominantly targets women, changes of body composition and total cholesterol may be less effective in weight cyclers than in non-weight cyclers. PMID:20052347

  18. The carboxy-terminus of p63 links cell cycle control and the proliferative potential of epidermal progenitor cells

    PubMed Central

    Suzuki, Daisuke; Sahu, Raju; Leu, N. Adrian; Senoo, Makoto

    2015-01-01

    The transcription factor p63 (Trp63) plays a key role in homeostasis and regeneration of the skin. The p63 gene is transcribed from dual promoters, generating TAp63 isoforms with growth suppressive functions and dominant-negative ΔNp63 isoforms with opposing properties. p63 also encodes multiple carboxy (C)-terminal variants. Although mutations of C-terminal variants have been linked to the pathogenesis of p63-associated ectodermal disorders, the physiological role of the p63 C-terminus is poorly understood. We report here that deletion of the p63 C-terminus in mice leads to ectodermal malformation and hypoplasia, accompanied by a reduced proliferative capacity of epidermal progenitor cells. Notably, unlike the p63-null condition, we find that p63 C-terminus deficiency promotes expression of the cyclin-dependent kinase inhibitor p21Waf1/Cip1 (Cdkn1a), a factor associated with reduced proliferative capacity of both hematopoietic and neuronal stem cells. These data suggest that the p63 C-terminus plays a key role in the cell cycle progression required to maintain the proliferative potential of stem cells of many different lineages. Mechanistically, we show that loss of Cα, the predominant C-terminal p63 variant in epithelia, promotes the transcriptional activity of TAp63 and also impairs the dominant-negative activity of ΔNp63, thereby controlling p21Waf1/Cip1 expression. We propose that the p63 C-terminus links cell cycle control and the proliferative potential of epidermal progenitor cells via mechanisms that equilibrate TAp63 and ΔNp63 isoform function. PMID:25503409

  19. Changes in Circulating Levels and Ratios of Angiopoietins during Pregnancy, but not during the Menstrual Cycle and Controlled Ovarian Stimulation

    PubMed Central

    Hurliman, Amanda K.; Speroff, Leon; Stouffer, Richard L.; Patton, Phillip E.; Lee, Annette; Molskness, Theodore A.

    2009-01-01

    OBJECTIVE This study was designed to determine if angiopoietin (ANGPT)-1 and -2 are detectable in the circulation of nonhuman primates and women, and if these levels fluctuate in association with ovarian activity. DESIGN Prospective SETTING National Primate Research Center, medical center and infertility clinic. PATIENTS Adult, female rhesus monkeys; 15 women donating oocytes for infertility treatment. INTERVENTIONS Controlled ovarian stimulation with gonadotropins, removal of the corpus luteum and ovaries, oocyte retrieval and embryo transfer. MAIN OUTCOME MEASURE Circulating levels of ANGPT-1 and ANGPT-2. RESULTS Serum ANGPT-1 and ANGPT-2 levels were detectable and invariant in maintaining an ANGPT1:2 ratio >1 in: (a) macaques over the course of the natural menstrual cycle, during a controlled ovulation protocol and following removal of the corpus luteum or ovaries, and (b) women undergoing controlled ovarian simulation (COS). In contrast, the ANGPT1:2 ratio was markedly decreased (≪1) at mid-to-late gestation in macaques, and in the follicular fluid of women undergoing COS, due to increased levels of ANGPT-2. CONCLUSIONS The ovary and its dominant structures are not major contributors to circulating levels of ANGPT-1 or ANGPT-2. The physiologic importance of the rising levels of ANGPT-2 after the luteal-placental shift in pregnancy is unknown. PMID:19476937

  20. Thermochemical cycles

    NASA Technical Reports Server (NTRS)

    Funk, J. E.; Soliman, M. A.; Carty, R. H.; Conger, W. L.; Cox, K. E.; Lawson, D.

    1975-01-01

    The thermochemical production of hydrogen is described along with the HYDRGN computer program which attempts to rate the various thermochemical cycles. Specific thermochemical cycles discussed include: iron sulfur cycle; iron chloride cycle; and hybrid sulfuric acid cycle.

  1. Life-cycle-assessment of the historical development of air pollution control and energy recovery in waste incineration.

    PubMed

    Damgaard, Anders; Riber, Christian; Fruergaard, Thilde; Hulgaard, Tore; Christensen, Thomas H

    2010-07-01

    Incineration of municipal solid waste is a debated waste management technology. In some countries it is the main waste management option whereas in other countries it has been disregarded. The main discussion point on waste incineration is the release of air emissions from the combustion of the waste, but also the energy recovery efficiency has a large importance. The historical development of air pollution control in waste incineration was studied through life-cycle-assessment modelling of eight different air pollution control technologies. The results showed a drastic reduction in the release of air emissions and consequently a significant reduction in the potential environmental impacts of waste incineration. Improvements of a factor 0.85-174 were obtained in the different impact potentials as technology developed from no emission control at all, to the best available emission control technologies of today (2010). The importance of efficient energy recovery was studied through seven different combinations of heat and electricity recovery, which were modelled to substitute energy produced from either coal or natural gas. The best air pollution control technology was used at the incinerator. It was found that when substituting coal based energy production total net savings were obtained in both the standard and toxic impact categories. However, if the substituted energy production was based on natural gas, only the most efficient recovery options yielded net savings with respect to the standard impacts. With regards to the toxic impact categories, emissions from the waste incineration process were always larger than those from the avoided energy production based on natural gas. The results shows that the potential environmental impacts from air emissions have decreased drastically during the last 35 years and that these impacts can be partly or fully offset by recovering energy which otherwise should have been produced from fossil fuels like coal or natural gas.

  2. Life-cycle-assessment of the historical development of air pollution control and energy recovery in waste incineration

    SciTech Connect

    Damgaard, Anders; Riber, Christian; Fruergaard, Thilde; Hulgaard, Tore; Christensen, Thomas H.

    2010-07-15

    Incineration of municipal solid waste is a debated waste management technology. In some countries it is the main waste management option whereas in other countries it has been disregarded. The main discussion point on waste incineration is the release of air emissions from the combustion of the waste, but also the energy recovery efficiency has a large importance. The historical development of air pollution control in waste incineration was studied through life-cycle-assessment modelling of eight different air pollution control technologies. The results showed a drastic reduction in the release of air emissions and consequently a significant reduction in the potential environmental impacts of waste incineration. Improvements of a factor 0.85-174 were obtained in the different impact potentials as technology developed from no emission control at all, to the best available emission control technologies of today (2010). The importance of efficient energy recovery was studied through seven different combinations of heat and electricity recovery, which were modelled to substitute energy produced from either coal or natural gas. The best air pollution control technology was used at the incinerator. It was found that when substituting coal based energy production total net savings were obtained in both the standard and toxic impact categories. However, if the substituted energy production was based on natural gas, only the most efficient recovery options yielded net savings with respect to the standard impacts. With regards to the toxic impact categories, emissions from the waste incineration process were always larger than those from the avoided energy production based on natural gas. The results shows that the potential environmental impacts from air emissions have decreased drastically during the last 35 years and that these impacts can be partly or fully offset by recovering energy which otherwise should have been produced from fossil fuels like coal or natural gas.

  3. Hybrid Type Humidity Control System Coupling a Desiccant Rotor in a Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Horibe, Akihiko; Takaki, Sadao; Inaba, Hideo; Haruki, Naoto

    This paper describes a new hybrid humidity control system that combines a desiccant rotor with a vapor compression refrigerator. This rotor uses a kind of advanced sorbent and desorption at low temperature below 50°C is possible. Therefore the rotor can be recovered by exhaust heat of a condenser. Applying the new hybrid system, we installed an experimental prototype and investigated its performance. As a result, dehumidification can be achieved even if the absolute humidity of the processing air is less than 0.002 kg/kg'. This suggests that water can be taken out from the exhausting air to humidify the returning air in winter. Furthermore, dehumidification efficiency is 4.1kg/kWh, system COP1.8 for the processing air 30°C, 62%RH. That corresponds with the summer weather condition. If it is winter, the dehumidification efficiency is 1.9kg/kWh, system COP0.97 for the processing air 22°C, 50%RH.

  4. Four-wall turbine airfoil with thermal strain control for reduced cycle fatigue

    SciTech Connect

    Cambell, Christian X

    2013-09-17

    A turbine airfoil (20B) with a thermal expansion control mechanism that increases the airfoil camber (60, 61) under operational heating. The airfoil has four-wall geometry, including pressure side outer and inner walls (26, 28B), and suction side outer and inner walls (32, 34B). It has near-wall cooling channels (31F, 31A, 33F, 33A) between the outer and inner walls. A cooling fluid flow pattern (50C, 50W, 50H) in the airfoil causes the pressure side inner wall (28B) to increase in curvature under operational heating. The pressure side inner wall (28B) is thicker than walls (26, 34B) that oppose it in camber deformation, so it dominates them in collaboration with the suction side outer wall (32), and the airfoil camber increases. This reduces and relocates a maximum stress area (47) from the suction side outer wall (32) to the suction side inner wall (34B, 72) and the pressure side outer wall (26).

  5. Management control and status reports documentation standard and Data Item Descriptions (DID). Volume of the information system life-cycle and documentation standards, volume 5

    NASA Technical Reports Server (NTRS)

    Callender, E. David; Steinbacher, Jody

    1989-01-01

    This is the fifth of five volumes on Information System Life-Cycle and Documentation Standards. This volume provides a well organized, easily used standard for management control and status reports used in monitoring and controlling the management, development, and assurance of informations systems and software, hardware, and operational procedures components, and related processes.

  6. Controls on Soil and Stream Nitrogen Cycling in a Mountain-to-Urban Watershed

    NASA Astrophysics Data System (ADS)

    Weintraub, S. R.; Bowen, G. J.; Hall, S. J.; Brooks, P. D.; Ehleringer, J. R.; Bowling, D. R.

    2015-12-01

    Human activities in cities contribute large quantities of nitrogen (N) to adjacent ecosystems, but it is unclear how various sources of anthropogenic N contribute to and move through local watersheds. We analyzed myriad soil and water samples from across the Jordan River Valley, Salt Lake City, UT in order to assess N dynamics in terrestrial systems, at the riparian-stream interface, and in streams in this coupled human-natural system. We used data from two terrestrial headwater sites to demonstrate that forests tend to be more N-rich in topographic lows compared to hillslopes. Regardless of landscape position, soils beneath herbaceous vegetation had high nitrate concentrations and enriched δ15N values, suggesting overall N richness compared to forests. Isotope data showed that nitrate from all soils and headwater streams was of microbial, rather than direct anthropogenic, origin. In addition, nitrate from nearby streams was isotopically distinct from upland soils, suggesting low hydrologic connectivity between the two. Using data from the headwaters as well as eight additional downstream sites, we found that riparian soil N pools were increasingly decoupled from stream N dynamics lower in the watershed. This was related to where the stream transitioned from gaining to losing water from the groundwater system. Stream N contents were low in undisturbed mountain waters, but increased ten-fold at sites contaminated with urban groundwater. Across five watersheds spanning the Jordan Valley, we found anthropogenic N increasingly impacted streams as watershed size and land use intensity increased. Wastewater treatment plants imparted a further order-of-magnitude increase in stream nitrate concentrations and isotope values. Our work demonstrates that controls on N dynamics shift from topography and vegetation in upper watersheds to groundwater-surface water interactions and human activities in lower, more developed reaches. While the adjacent wildland ecosystem appears to

  7. Ssrp1a controls organogenesis by promoting cell cycle progression and RNA synthesis

    PubMed Central

    Koltowska, Katarzyna; Apitz, Holger; Stamataki, Despina; Hirst, Elizabeth M. A.; Verkade, Heather; Salecker, Iris; Ober, Elke A.

    2013-01-01

    Tightly controlled DNA replication and RNA transcription are essential for differentiation and tissue growth in multicellular organisms. Histone chaperones, including the FACT (facilitates chromatin transcription) complex, are central for these processes and act by mediating DNA access through nucleosome reorganisation. However, their roles in vertebrate organogenesis are poorly understood. Here, we report the identification of zebrafish mutants for the gene encoding Structure specific recognition protein 1a (Ssrp1a), which, together with Spt16, forms the FACT heterodimer. Focussing on the liver and eye, we show that zygotic Ssrp1a is essential for proliferation and differentiation during organogenesis. Specifically, gene expression indicative of progressive organ differentiation is disrupted and RNA transcription is globally reduced. Ssrp1a-deficient embryos exhibit DNA synthesis defects and prolonged S phase, uncovering a role distinct from that of Spt16, which promotes G1 phase progression. Gene deletion/replacement experiments in Drosophila show that Ssrp1b, Ssrp1a and N-terminal Ssrp1a, equivalent to the yeast homologue Pob3, can substitute Drosophila Ssrp function. These data suggest that (1) Ssrp1b does not compensate for Ssrp1a loss in the zebrafish embryo, probably owing to insufficient expression levels, and (2) despite fundamental structural differences, the mechanisms mediating DNA accessibility by FACT are conserved between yeast and metazoans. We propose that the essential functions of Ssrp1a in DNA replication and gene transcription, together with its dynamic spatiotemporal expression, ensure organ-specific differentiation and proportional growth, which are crucial for the forming embryo. PMID:23515471

  8. Climate Versus Local Cave Environment Controls on Trace Element and Stable Isotopic Cycles in Annual Laminae in Speleothem

    NASA Astrophysics Data System (ADS)

    Mattey, D.; Grassineau, N. V.; Muller, W.; Garcia-Anton, E.; Fairchild, I. J.

    2011-12-01

    Three types of laminae are commonly observed in stalagmites: visible, resulting from alternating crystal morphology, fluid inclusion abundance or calcite-aragonite couplets; fluorescent, related to captured organic matter and cryptic, defined by cyclical abundances of trace elements or stable isotopes. Many processes generate laminae but in regions where there are strong primary cycles in climate, annual lamination may form as a direct result of seasonal change in precipitation, temperature and vegetation or the indirect effects of local cave processes such as ventilation. Visible, fluorescent and cryptic lamination types are often all present and closely correlated in the same stalagmite, but the correspondence of annual cycles in fabric, trace element and stable isotopes, can be dissimilar in different regions of the world, or even from different areas in the same cave system. This especially applies to the interrelationships among trace elements and stable isotopes where controls on their behavior seem specific to the local environment, making generalised interpretations problematic. This study presents seasonally resolved stable isotope (20-100 μm resolution) and trace element (10 μm resolution by LA-ICPMS) data for visible laminae for which there is compelling evidence for annularity. Five cave sites with diverse regional climates and local microenvironments are compared: Voli Voli, Fiji (VV) and Krem Umsynrang, India (KU) are caves from tropical or subtropical environments with strong seasonal rainfall in summer months and a relatively small annual temperature range; New St Michaels Cave, Gibraltar (NSM) is a strongly seasonal Mediterranean site with winter rainfall and a large annual temperature range; Marble Arch, N. Ireland (MA) and High Pasture, Skye (HP) are British cave sites from temperate maritime climates where seasonality in temperature and rainfall is weaker. Laminae at the tropical sites with highest rainfall, VV and KU, show weakest seasonality

  9. Cell-cycle-controlled radiation therapy was effective for treating a murine malignant melanoma cell line in vitro and in vivo

    PubMed Central

    Otani, Keisuke; Naito, Yoko; Sakaguchi, Yukako; Seo, Yuji; Takahashi, Yutaka; Kikuta, Junichi; Ogawa, Kazuhiko; Ishii, Masaru

    2016-01-01

    Radiotherapy is a commonly used regimen for treating various types of intractable cancers, although the effects depend on the cell cycle of the targeted cancer cell lines, and for irradiation purposes it is therefore critical to establish a protocol for controlling the cell cycle. Here, we showed that a common murine melanoma cell line B16BL6 was more vulnerable to irradiation during the early S phase, and that synchronisation of the cell cycle greatly increased the therapeutic effects of radiotherapy. Cell-sorting experiments, according to cell-cycle phase, using B16BL6 cells demonstrated that cells in the early S phase were the most susceptible to radiotherapy. Gemcitabine, a clinically utilised anti-cancer drug, induced cell-cycle arrest during the early S phase in B16BL6 cells, and thus a synergistic therapeutic effect was observed when irradiation was administered at the right time. Human pancreatic cancer cell line PANC-1 exhibited similar properties to B16BL6 in terms of its radiosensitivity during the S/G2/M phase and also demonstrated a synergistic effect of cell cycle synchronisation. These results show the importance of cell-cycle control in the application of irradiation and suggest a suitable time interval between chemotherapy and radiotherapy, as well as providing useful information for treating intractable cancer. PMID:27480052

  10. Water table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

    NASA Astrophysics Data System (ADS)

    Lipson, D. A.; Zona, D.; Raab, T. K.; Bozzolo, F.; Mauritz, M.; Oechel, W. C.

    2011-07-01

    Drained thaw lake basins (DTLB) are the dominant land form of the Arctic coastal plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in these complex landscapes. Here we report the effects of experimental flooding, along with seasonal and spatial variation in soil chemistry and microbial activity in a DTLB. The flooding treatment generally mirrored the effects of natural landscape variation in water table height due to microtopography. Areas in the flooded areas had lower dissolved oxygen, lower oxidation-reduction potential (ORP) and higher pH, as did lower elevation areas of the landscape. Similarly, soil pore water concentrations of dissolved ferric iron (Fe III), organic carbon, and aromatic compounds were higher in flooded and low elevation areas. Dissolved carbon dioxide (CO2) and methane (CH4) concentrations were higher in low elevation areas. In anaerobic laboratory incubations, more CH4 was produced by soils from low and flooded areas, whereas anaerobic CO2 production only responded to flooding in high elevation areas. Seasonal changes in the oxidation state of solid phase Fe minerals showed that significant dissimilatory Fe reduction occurred, especially in topographically low areas. This suite of results can all be attributed to the effect of water table on oxygen availability: flooded conditions promote anoxia, stimulating anaerobic processes, methanogenesis and Fe(III) reduction. Flooding also increased soil temperature, which might

  11. Feedback control of combustion instabilities from within limit cycle oscillations using H∞ loop-shaping and the ν-gap metric

    NASA Astrophysics Data System (ADS)

    Li, Jingxuan; Morgans, Aimee S.

    2016-07-01

    Combustion instabilities arise owing to a two-way coupling between acoustic waves and unsteady heat release. Oscillation amplitudes successively grow, until nonlinear effects cause saturation into limit cycle oscillations. Feedback control, in which an actuator modifies some combustor input in response to a sensor measurement, can suppress combustion instabilities. Linear feedback controllers are typically designed, using linear combustor models. However, when activated from within limit cycle, the linear model is invalid, and such controllers are not guaranteed to stabilize. This work develops a feedback control strategy guaranteed to stabilize from within limit cycle oscillations. A low-order model of a simple combustor, exhibiting the essential features of more complex systems, is presented. Linear plane acoustic wave modelling is combined with a weakly nonlinear describing function for the flame. The latter is determined numerically using a level set approach. Its implication is that the open-loop transfer function (OLTF) needed for controller design varies with oscillation level. The difference between the mean and the rest of the OLTFs is characterized using the ν-gap metric, providing the minimum required `robustness margin' for an H∞ loop-shaping controller. Such controllers are designed and achieve stability both for linear fluctuations and from within limit cycle oscillations.

  12. Feedback control of combustion instabilities from within limit cycle oscillations using H∞ loop-shaping and the ν-gap metric

    PubMed Central

    Morgans, Aimee S.

    2016-01-01

    Combustion instabilities arise owing to a two-way coupling between acoustic waves and unsteady heat release. Oscillation amplitudes successively grow, until nonlinear effects cause saturation into limit cycle oscillations. Feedback control, in which an actuator modifies some combustor input in response to a sensor measurement, can suppress combustion instabilities. Linear feedback controllers are typically designed, using linear combustor models. However, when activated from within limit cycle, the linear model is invalid, and such controllers are not guaranteed to stabilize. This work develops a feedback control strategy guaranteed to stabilize from within limit cycle oscillations. A low-order model of a simple combustor, exhibiting the essential features of more complex systems, is presented. Linear plane acoustic wave modelling is combined with a weakly nonlinear describing function for the flame. The latter is determined numerically using a level set approach. Its implication is that the open-loop transfer function (OLTF) needed for controller design varies with oscillation level. The difference between the mean and the rest of the OLTFs is characterized using the ν-gap metric, providing the minimum required ‘robustness margin’ for an H∞ loop-shaping controller. Such controllers are designed and achieve stability both for linear fluctuations and from within limit cycle oscillations. PMID:27493558

  13. An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics.

    PubMed

    Fu, Chunjiang; Suzuki, Yasuyuki; Kiyono, Ken; Morasso, Pietro; Nomura, Taishin

    2014-12-01

    Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather

  14. Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake

    USGS Publications Warehouse

    Stoliker, Deborah L.; Repert, Deborah A.; Smith, Richard L.; Song, Bongkeun; LeBlanc, Denis R.; McCobb, Timothy D.; Conaway, Christopher; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B.

    2016-01-01

    The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.

  15. Small RNA-dependent expression of secondary metabolism is controlled by Krebs cycle function in Pseudomonas fluorescens.

    PubMed

    Takeuchi, Kasumi; Kiefer, Patrick; Reimmann, Cornelia; Keel, Christoph; Dubuis, Christophe; Rolli, Joëlle; Vorholt, Julia A; Haas, Dieter

    2009-12-11

    Pseudomonas fluorescens CHA0, an antagonist of phytopathogenic fungi in the rhizosphere of crop plants, elaborates and excretes several secondary metabolites with antibiotic properties. Their synthesis depends on three small RNAs (RsmX, RsmY, and RsmZ), whose expression is positively controlled by the GacS-GacA two-component system at high cell population densities. To find regulatory links between primary and secondary metabolism in P. fluorescens and in the related species Pseudomonas aeruginosa, we searched for null mutations that affected central carbon metabolism as well as the expression of rsmY-gfp and rsmZ-gfp reporter constructs but without slowing down the growth rate in rich media. Mutation in the pycAB genes (for pyruvate carboxylase) led to down-regulation of rsmXYZ and secondary metabolism, whereas mutation in fumA (for a fumarase isoenzyme) resulted in up-regulation of the three small RNAs and secondary metabolism in the absence of detectable nutrient limitation. These effects required the GacS sensor kinase but not the accessory sensors RetS and LadS. An analysis of intracellular metabolites in P. fluorescens revealed a strong positive correlation between small RNA expression and the pools of 2-oxoglutarate, succinate, and fumarate. We conclude that Krebs cycle intermediates (already known to control GacA-dependent virulence factors in P. aeruginosa) exert a critical trigger function in secondary metabolism via the expression of GacA-dependent small RNAs.

  16. Hydrologic Controls on Nitrogen Cycling Processes and Functional Gene Abundance in Sediments of a Groundwater Flow-Through Lake.

    PubMed

    Stoliker, Deborah L; Repert, Deborah A; Smith, Richard L; Song, Bongkeun; LeBlanc, Denis R; McCobb, Timothy D; Conaway, Christopher H; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B

    2016-04-01

    The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient. PMID:26967929

  17. Control of the estrous cycle to improve fertility for fixed-time artificial insemination in beef cattle: a review.

    PubMed

    Lamb, G C; Dahlen, C R; Larson, J E; Marquezini, G; Stevenson, J S

    2010-04-01

    Early estrus-synchronization protocols focused on regressing the corpus luteum (CL) with an injection of PGF(2alpha) followed by detection of estrus or involved the use of exogenous progestins that prevent estrus from occurring. Later, protocols combining the use of PGF(2alpha) and exogenous progestins were developed. Gonadotropin-releasing hormone was utilized to control follicular waves, synchronize ovulation, or to luteinize large dominant follicles. Our research aimed to develop reliable protocols that 1) relied solely on fixed-timed AI (TAI); 2) required a maximum of 3 animal handlings, and 3) were successful in estrous-cycling and noncycling females. In cows, insertion of an intravaginal progesterone insert during the 7-d interval between the initial GnRH and PGF(2alpha) injections enhanced pregnancy rates by 9 to 10%. In a multi-location study, a TAI protocol yielded pregnancy rates similar to a protocol involving detection of estrus plus a fixed-time clean-up AI for females not detected in estrus (54 vs. 58%, respectively, for cows and 53 vs. 57%, respectively, for heifers). Initiation of estrous cycles in noncycling cows is likely the primary manner in which beef producers may improve fertility in response to estrus synchronization and TAI protocols. Treatment of noncycling females with progesterone and GnRH increases the percentage of cycling females and improves fertility to a TAI, but inducing cyclicity with hCG failed to enhance fertility in TAI protocols. Supplementing progesterone after TAI failed to increase pregnancy rates in beef cattle. In contrast, administration of hCG 7 d after TAI induced an accessory CL, increased progesterone, and tended to enhance pregnancy rates. Development of TAI protocols that reduce the hassle factors associated with ovulation synchronization and AI provide cattle producers efficient and effective tools for capturing selective genetic traits of economic consequences. Location variables, however, which may include

  18. Heterotrophic bacterioplankton control on organic and inorganic carbon cycle in stratified and non-stratified lakes of NW Russia

    NASA Astrophysics Data System (ADS)

    Shirokova, Liudmila; Vorobjeva, Taissia; Zabelina, Svetlana; Moreva, Olga; Klimov, Sergey; Shorina, Natalja; Chupakov, Artem; Pokrovsky, Oleg; Audry, Stephan; Viers, Jerome

    2010-05-01

    Lakes of boreal zone regulate the fate of dissolved carbon, nutrients and trace metals during their transport from the watershed to the ocean. Study of primary production - mineralization processes in the context of carbon biogeochemical cycle allows determination of the rate and mechanisms of phytoplankton biomass production and its degradation via aquatic heterotrophic bacteria. In particular, comparative study of vertical distribution of Dissolved Organic Carbon (DOC) in stratified and non-stratified lakes allows establishing the link between biological and chemical aspects of the carbon cycle which, in turns, determines an environmental stability and recovering potential of the entire ecosystem. In order to better understand the biogeochemical mechanisms that control dissolved organic and inorganic carbon migration in surface boreal waters, we studied in 2007-2009 two strongly stratified lakes (15-20 m deep) and two shallow lakes (2-4 m deep) in the Arkhangelsk region (NW Russia, White Sea basin). We conducted natural experiments of the lake water incubation for measurements of the intensity of production/mineralization processes and we determined vertical concentration of DOC during four basic hydrological seasons (winter and summer stratification, and spring and autumn lake overturn). Our seasonal studies of production/mineralization processes demonstrated high intensity of organic matter formation during summer period and significant retard of these processes during winter stagnation. During spring period, there is a strong increase of bacterial destruction of the allochtonous organic matter that is being delivered to the lake via terrigenous input. During autumn overturn, there is a decrease of the activity of phytoplankton, and the degradation of dead biomass by active bacterial community. Organic matter destruction processes are the most active in Svyatoe lake, whereas in the Beloe lake, the rate of organic matter production is significantly higher than

  19. Biogenic and pedogenic controls on Si distributions and cycling in grasslands of the Santa Cruz soil chronosequence, California

    NASA Astrophysics Data System (ADS)

    White, Art F.; Vivit, Davison V.; Schulz, Marjorie S.; Bullen, Tom D.; Evett, Rand R.; Aagarwal, Jugdeep

    2012-10-01

    Biogenic and pedogenic processes control silica cycling in grasslands growing on a soil chronosequence and dominated by strong seasonal variabilities of a Mediterranean climate. Shallow pore water Si, in spite of significant annual uptake and release by plant growth and dieback, exhibits only moderate seasonal fluctuations reflecting strong buffering from labile biogenic Si, dominated by phytoliths and by secondary pedogenic silicates. Long phytolith residence times (340-900 yrs) reflect the seasonally dry climate and high solute Si concentrations. Water-extractable Si is closely associated with Al, indicating seasonal precipitation and dissolution of a highly labile 1:1 hydroxyaluminosilicate (HAS), probably allophane, which transforms in deeper soil into fine grained, poorly crystalline kaolinite. Shallow plant roots extract greater proportions of biogenic Si and deeper plant roots larger amounts pedogenic Si. High pore water Ge/Si in late winter and spring reflects the reinforcing effects of plant fractionation and concurrent dissolution of Ge-enriched HAS. The same processes produce pore waters with depleted 30Si/28Si. In the summer and fall, Ge/Si declines and 30Si/28Si increases, reflecting the cessation of plant uptake, continued dissolution of soil phytoliths and re-precipitation of less soluble HAS. Si inputs from weathering (2-90 mmol m-2 yr-1) and losses from pore water discharge (18-68 mM m-2 yr-1) are comparable for individual soils, decline with soil age and are significantly less than amounts of Si annual cycled through the vegetation (42-171 mM m-2 yr-1). Mobile Si is generally balanced in the soils with upward bio-pumping by the shallow-rooted grasses efficiently competing against downward leaching and pore water discharge. Small net annual increases in Si in the present day soils could not have been maintained over the time scale represented by the chronosequence (65-225 yrs), implying past changes in environmental conditions.

  20. Testing and analysis of the impact on engine cycle parameters and control system modifications using hydrogen or methane as fuel in an industrial gas turbine

    NASA Astrophysics Data System (ADS)

    Funke, H. H.-W.; Keinz, J.; Börner, S.; Hendrick, P.; Elsing, R.

    2016-07-01

    The paper highlights the modification of the engine control software of the hydrogen (H2) converted gas turbine Auxiliary Power Unit (APU) GTCP 36-300 allowing safe and accurate methane (CH4) operation achieved without mechanical changes of the metering unit. The acceleration and deceleration characteristics of the engine controller from idle to maximum load are analyzed comparing H2 and CH4. Also, the paper presents the influence on the thermodynamic cycle of gas turbine resulting from the different fuels supported by a gas turbine cycle simulation of H2 and CH4 using the software GasTurb.

  1. Checkpoints in the life-cycle of Cassiopea spp.: control of metagenesis and metamorphosis in a tropical jellyfish.

    PubMed

    Hofmann, D K; Fitt, W K; Fleck, J

    1996-02-01

    Experimental data reveal that most, if not all, major events in the metagenetic life-cycle of Cassiopea spp. at these checkpoints depend on the interaction with specific biotic and physical cues. For medusa formation within a permissive temperature range by monodisk strobilation of the polyp, the presence of endosymbiotic dinoflagellates is indispensable. The priming effect of the algal symbionts is not primarily coupled with photosynthetic activity, but was found to be enhanced in the light. Budding of larva-like propagules by the polyp, however, is independent from such zooxanthellae. On the other hand the budding rate is influenced by various rearing conditions. Exogenous chemical cues control settlement and metamorphosis into scyphopolyps of both sexually produced planula larvae and asexual propagules. In laboratory experiments two classes of metamorphosis inducing compounds have been detected: a family of oligopeptides, featuring a proline-residue next to the carboxyterminal amino acid, and several phorbol esters. Using the peptide 14C-DNS-GPGGPA, induction of metamorphosis has been shown to be receptor-mediated. Furthermore, activation of protein kinase C, a key enzyme within the inositolphospholipid-signalling pathway appears to be involved in initiating metamorphosis. In mangrove habitats of Cassiopea spp. planula larvae specifically settle and metamorphose on submerged, deteriorating mangrove leaves from which biologically active fractions have been isolated. The chemical characterisation and comparison of these compounds from the natural environment with the properties and mode of action of oligopeptide inducers is in progress. PMID:8735945

  2. Simulated Solar Flare X-Ray and Thermal Cycling Durability Evaluation of Hubble Space Telescope Thermal Control Candidate Replacement Materials

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Banks, Bruce A.; Sechkar, Edward A.; Scheiman, David A.

    1998-01-01

    During the Hubble Space Telescope (HST) second servicing mission (SM2), astronauts noticed that the multilayer insulation (MLI) covering the telescope was damaged. Large pieces of the outer layer of MLI (aluminized Teflon fluorinated ethylene propylene (Al-FEP)) were torn in several locations around the telescope. A piece of curled up Al-FEP was retrieved by the astronauts and was found to be severely embrittled, as witnessed by ground testing. Goddard Space Flight Center (GSFC) organized a HST MLI Failure Review Board (FRB) to determine the damage mechanism of FEP in the HST environment, and to recommend replacement insulation material to be installed on HST during the third servicing mission (SM3) in 1999. Candidate thermal control replacement materials were chosen by the FRB and tested for environmental durability under various exposures and durations. This paper describes durability testing of candidate materials which were exposed to charged particle radiation, simulated solar flare x-ray radiation and thermal cycling under load. Samples were evaluated for changes in solar absorptance and tear resistance. Descriptions of environmental exposures and durability evaluations of these materials are presented.

  3. Rho-associated kinase connects a cell cycle-controlling anchorage signal to the mammalian target of rapamycin pathway.

    PubMed

    Park, Jung-ha; Arakawa-Takeuchi, Shiho; Jinno, Shigeki; Okayama, Hiroto

    2011-07-01

    When deprived of anchorage to the extracellular matrix, fibroblasts arrest in G(1) phase at least in part due to inactivation of G(1) cyclin-dependent kinases. Despite great effort, how anchorage signals control the G(1)-S transition of fibroblasts remains highly elusive. We recently found that the mammalian target of rapamycin (mTOR) cascade might convey an anchorage signal that regulates S phase entry. Here, we show that Rho-associated kinase connects this signal to the TSC1/TSC2-RHEB-mTOR pathway. Expression of a constitutively active form of ROCK1 suppressed all of the anchorage deprivation effects suppressible by tsc2 mutation in rat embryonic fibroblasts. TSC2 contains one evolutionarily conserved ROCK target-like sequence, and an alanine substitution for Thr(1203) in this sequence severely impaired the ability of ROCK1 to counteract the anchorage loss-imposed down-regulation of both G(1) cell cycle factors and mTORC1 activity. Moreover, TSC2 Thr(1203) underwent ROCK-dependent phosphorylation in vivo and could be phosphorylated by bacterially expressed active ROCK1 in vitro, providing biochemical evidence for a direct physical interaction between ROCK and TSC2.

  4. A factor controlling long-term variations of the Siberian water cycles during the past two centuries

    NASA Astrophysics Data System (ADS)

    Oshima, Kazuhiro; Ogata, Koto; Park, Hotaek; Tachibana, Yoshihiro

    2016-04-01

    Among all the rivers flowing into the Arctic Ocean, the three great Siberian rivers; Lena, Yenisei and Ob, are the three largest in terms of discharge (R), and are sources of freshwater, organic matter and heat into the ocean. While long-term variation and trend of the Rs have been examined in a lot of previous studies, causes of the R variations are still unclear. A previous study indicated the negative correlation between the Lena and Ob Rs during the 1980s to mid-1990s and it was affected by an east-west seesaw pattern of atmospheric circulation over Siberia. Our analysis indicated that 15-year running correlations between observed Rs of the Lena and Ob becomes weak after the mid-1990s and it was positive in mid-1950s to 1960s. The similar relationships were seen in precipitation (P) over the two basins. As in the observed Rs, more long-term record of reconstructed Rs of the Lena and Ob based on the tree-ring showed positive, negative and weak correlations in each of the epochs during the past two centuries. Interestingly, the correlations of the reconstructed Rs tend to be distributed on the negative side. These negative correlations were associated with the east-west seesaw pattern, as in the previous study. In addition, the correlations of Ps over eastern and western Siberia in an atmospheric general circulation model (AGCM) control simulation were distributed on more negative side compared to those in the CMIP3 multi-coupled models' simulations. The results of the AGCM and CMIP3 models reveal that the seesaw pattern frequently appears as an atmospheric internal variability over Siberia. Therefore, our results indicated that the east-west seesaw pattern as an atmospheric internal variability is a key factor controlling the long-term variation of water cycles in Siberia region.

  5. Inhibitory role of ERβ on anterior pituitary cell proliferation by controlling the expression of proteins related to cell cycle progression.

    PubMed

    Pérez, Pablo A; Petiti, Juan P; Wagner, Ignacio A; Sabatino, Maria E; Sasso, Corina V; De Paul, Ana L; Torres, Alicia I; Gutiérrez, Silvina

    2015-11-01

    Considering that the role of ERβ in the growth of pituitary cells is not well known, the aim of this work was to determine the expression of ERβ in normal and tumoral cells and to investigate its implications in the proliferative control of this endocrine gland, by analyzing the participation of cyclin D1, Cdk4 and p21. Our results showed that the expression of ERβ decreased during pituitary tumoral development induced by chronic E2 stimulation. The 20 ± 1.6% of normal adenohypophyseal cells expressed ERβ, with this protein being reduced in the hyperplastic/adenomatous pituitary: at 20 days the ERβ+ population was 10.7 ± 2.2%, while after 40 and 60 days of treatment an almost complete loss in the ERβ expression was observed (40 d: 1 ± 0.6%; 60 d: 2 ± 0.6%). The ERα/β ratio increased starting from tumors at 40 days, mainly due to the loss of ERβ expression. The cell proliferation was analyzed in normal and hyperplastic pituitary and also in GH3β- and GH3β+ which contained different levels of ERβ expression, and therefore different ERα/β ratios. The over-expression of ERβ inhibited the GH3 cell proliferation and expression of cyclin D1 and ERα. Also, the ERβ activation by its agonist DPN changed the subcellular localization of p21, inducing an increase in the p21 nuclear expression, where it acts as a tumoral suppressor. These results show that ERβ exerts an inhibitory role on pituitary cell proliferation, and that this effect may be partially due to the modulation of some key regulators of the cell cycle, such as cyclin D1 and p21. These data contribute significantly to the understanding of the ER effects in the proliferative control of pituitary gland, specifically related to the ERβ function in the E2 actions on this endocrine gland.

  6. The circadian clock controls fluctuations of colonic cell proliferation during the light/dark cycle via feeding behavior in mice.

    PubMed

    Yoshida, Daisuke; Aoki, Natsumi; Tanaka, Mizuho; Aoyama, Shinya; Shibata, Shigenobu

    2015-01-01

    The mammalian circadian system is controlled not only by the suprachiasmatic nucleus (SCN), but also by the peripheral clocks located in tissues such as liver, kidney, small intestine, and colon, mediated through signals such as hormones. Peripheral clocks, but not the SCN, can be entrained by food intake schedules. While it is known that cell proliferation exhibits a circadian rhythm in the colon epithelium, it is unclear how this rhythm is influenced by food intake schedules. Here, we aimed to determine the relationships between feeding schedules and cell proliferation in the colon epithelium by means of immunochemical analysis, using 5-bromo-2'-deoxyuridine (BrdU), as well as to elucidate how feeding schedules influence the colonic expression of clock and cell cycle genes, using real-time reverse-transcription PCR (qRT-PCR). Cell proliferation in the colonic epithelium of normal mice exhibited a daily fluctuation, which was abrogated in Clock mutant mice. The day/night pattern of cellular proliferation and clock gene expression under daytime and nighttime restricted feeding (RF) schedules showed opposite tendencies. While daytime RF for every 4 h attenuated the day/night pattern of cell proliferation, this was restored to normal in the Clock mutant mice under the nighttime RF schedule. These results suggest that feeding schedules contribute to the establishment of a daily fluctuation of cell proliferation and RF can recover it in Clock mutant mice. Thus, this study demonstrates that the daily fluctuation of cell proliferation in the murine colon is controlled by a circadian feeding rhythm, suggesting that feeding schedules are important for rhythmicity in the proliferation of colon cells.

  7. Are signalized intersections with cycle tracks safer? A case-control study based on automated surrogate safety analysis using video data.

    PubMed

    Zangenehpour, Sohail; Strauss, Jillian; Miranda-Moreno, Luis F; Saunier, Nicolas

    2016-01-01

    Cities in North America have been building bicycle infrastructure, in particular cycle tracks, with the intention of promoting urban cycling and improving cyclist safety. These facilities have been built and expanded but very little research has been done to investigate the safety impacts of cycle tracks, in particular at intersections, where cyclists interact with turning motor-vehicles. Some safety research has looked at injury data and most have reached the conclusion that cycle tracks have positive effects of cyclist safety. The objective of this work is to investigate the safety effects of cycle tracks at signalized intersections using a case-control study. For this purpose, a video-based method is proposed for analyzing the post-encroachment time as a surrogate measure of the severity of the interactions between cyclists and turning vehicles travelling in the same direction. Using the city of Montreal as the case study, a sample of intersections with and without cycle tracks on the right and left sides of the road were carefully selected accounting for intersection geometry and traffic volumes. More than 90h of video were collected from 23 intersections and processed to obtain cyclist and motor-vehicle trajectories and interactions. After cyclist and motor-vehicle interactions were defined, ordered logit models with random effects were developed to evaluate the safety effects of cycle tracks at intersections. Based on the extracted data from the recorded videos, it was found that intersection approaches with cycle tracks on the right are safer than intersection approaches with no cycle track. However, intersections with cycle tracks on the left compared to no cycle tracks seem to be significantly safer. Results also identify that the likelihood of a cyclist being involved in a dangerous interaction increases with increasing turning vehicle flow and decreases as the size of the cyclist group arriving at the intersection increases. The results highlight the

  8. [Life support of the Mars exploration crew. Control of a zeolite system for carbon dioxide removal from space cabin air within a closed air regeneration cycle].

    PubMed

    Chekov, Iu F

    2009-01-01

    The author describes a zeolite system for carbon dioxide removal integrated into a closed air regeneration cycle aboard spacecraft. The continuous operation of a double-adsorbent regeneration system with pCO2-dependable productivity is maintained through programmable setting of adsorption (desorption) semicycle time. The optimal system regulation curve is presented within the space of statistical performance family obtained in quasi-steady operating modes with controlled parameters of the recurrent adsorption-desorption cycle. The automatically changing system productivity ensures continuous intake of concentrated CO2. Control of the adsorption-desorption process is based on calculation of the differential adsorption (desorption) heat from gradient of adsorbent and test inert substance temperatures. The adaptive algorithm of digital control is implemented through the standard spacecraft interface with the board computer system and programmable microprocessor-based controllers. PMID:19621802

  9. The PEDALS Stationary Cycling Intervention and Health-Related Quality of Life in Children with Cerebral Palsy: A Randomized Controlled Trial

    ERIC Educational Resources Information Center

    DeMuth, Sharon K.; Knutson, Loretta M.; Fowler, Eileen G.

    2012-01-01

    Aim: The aim of this study was to assess health-related quality of life (HRQOL) following a stationary cycling intervention in children with cerebral palsy (CP). Method: This was a phase I multisite randomized controlled trial with single blinding. HRQOL was evaluated using the Pediatric Quality of Life Inventory SF15 (PedsQL; children) and…

  10. Cycling/dispatching power plants

    SciTech Connect

    Makansi, J.

    1994-02-01

    This article examines the effect cycling capability has on a power systems plants and the tradeoffs in performance that may occur. The topics of this article include cycling capability, control and training tools, combined cycles, steam turbine selection, protection against water induction, plant staffing, boiler/steam turbines, full turbine bypasses, cycling of CFB boilers, generators, and environmental control system uses to monitor performance.

  11. Realization of the Atkinson-Miller cycle in spark-ignition engine by means of the fully variable inlet valve control system

    NASA Astrophysics Data System (ADS)

    Żmudka, Zbigniew; Postrzednik, Stefan; Przybyła, Grzegorz

    2014-09-01

    The theoretical analysis of the charge exchange process in a spark ignition engine has been presented. This process has significant impact on the effectiveness of engine operation because it is related to the necessity of overcoming the flow resistance, followed by the necessity of doing a work, so-called the charge exchange work. The flow resistance caused by the throttling valve is especially high during the part load operation. The open Atkinson-Miller cycle has been assumed as a model of processes taking place in the engine. Using fully variable inlet valve timing the A-M cycle can be realized according to two systems: system with late inlet valve closing and system with early inlet valve closing. The systems have been analysed individually and comparatively with the open Seiliger-Sabathe cycle which is a theoretical cycle for the classical throttle governing of the engine load. Benefits resulting from application of the systems with independent inlet valve control have been assessed on the basis of the selected parameters: fuel dose, cycle work, charge exchange work and a cycle efficiency. The use of the analysed systems to governing of the SI engine load will enable to eliminate a throttling valve from the system inlet and reduce the charge exchange work, especially within the range of part load operation.

  12. Isostasy-controlled thinning-upward cycles in the Mediterranean?; a comparison with the Zechstein salt giant

    NASA Astrophysics Data System (ADS)

    Van den Belt, Frank J. G.; De Boer, Poppe L.

    2014-05-01

    The desiccated deep-basin model, originally developed for the Mediterranean salt giant, deviated significantly from existing models and it has never been satisfactorily translated into a general concept. With time, however, Mediterranean models evolved towards moderate basin depths and the view that deposition took place in a flooded basin has gained reputation. These new insights have bridged the gap with general evaporite models and open possibilities of integrating concepts developed for other salt giants into the model. Recent modelling work (Van den Belt & De Boer, 2012) based on the Zechstein salt basin has shown that the thickness and composition of subsequent evaporite cycles can be explained by a model that involves a repetition of a three-stage process of 1) progressive narrowing of an ocean corridor in response to sulphate-platform progradation, resulting in 2) brine concentration and rapid infilling of the basin with halite and potash salts, the load of which causes 3) isostatic creation of accommodation space for the next cycle. Isostatic theory predicts that each cycle has approximately half the thickness of the previous one, e.g. 1.0 > 0.50 > 0.25 > 0.125 followed by a number of (coalesced) smaller cycles with a joint thickness of 0.125. The sequence in the basin centre then adds up to 2, which is two times the original basin depth. For the Zechstein case actual cycle thickness well matches these predicted values with cycle thicknesses of about 1.06 > 0.54 > 0.18 > 0.10 and 0.12. The cycle build-up of the Mediterranean salt giant is less well known, because of limited deep drilling. There are at least two cycles, a thin upper overlying a thick lower unit, but comparison of Zechstein patterns with Mediterranean sections has shown that more cycles may be present. Typical cycle boundaries include K/Mg-salt interbeds in halite units, and halite interbeds in sulphate units. Interestingly, analysis has shown that such indicators in Mediterranean sections

  13. MYB3Rs, plant homologs of Myb oncoproteins, control cell cycle-regulated transcription and form DREAM-like complexes.

    PubMed

    Kobayashi, Kosuke; Suzuki, Toshiya; Iwata, Eriko; Magyar, Zoltán; Bögre, László; Ito, Masaki

    2015-01-01

    Plant MYB3R transcription factors, homologous to Myb oncoproteins, regulate the genes expressed at G2 and M phases in the cell cycle. Recent studies showed that MYB3Rs constitute multiprotein complexes that may correspond to animal complexes known as DREAM or dREAM. Discovery of the putative homologous complex in plants uncovered their significant varieties in structure, function, dynamics, and heterogeneity, providing insight into conserved and diversified aspects of cell cycle-regulated gene transcription.

  14. Control by Nutrients of Growth and Cell Cycle Progression in Budding Yeast, Analyzed by Double-Tag Flow Cytometry

    PubMed Central

    Alberghina, Lilia; Smeraldi, Carla; Ranzi, Bianca Maria; Porro, Danilo

    1998-01-01

    To gain insight on the interrelationships of the cellular environment, the properties of growth, and cell cycle progression, we analyzed the dynamic reactions of individual Saccharomyces cerevisiae cells to changes and manipulations of their surroundings. We used a new flow cytometric approach which allows, in asynchronous growing S. cerevisiae populations, tagging of both the cell age and the cell protein content of cells belonging to the different cell cycle set points. Since the cell protein content is a good estimation of the cell size, it is possible to follow the kinetics of the cell size increase during cell cycle progression. The analysis of the findings obtained indicates that both during a nutritional shift-up (from ethanol to glucose) and following the addition of cyclic AMP (cAMP), two important delays are induced. The preexisting cells that at the moment of the nutritional shift-up were cycling before the Start phase delay their entrance into S phase, while cells that were cycling after Start are delayed in their exit from the cycle. The combined effects of the two delays allow the cellular population that preexisted the shift-up to quickly adjust to the new growth condition. The effects of a nutritional shift-down were also determined. PMID:9683483

  15. A dual-mode highly efficient class-E stimulator controlled by a low-Q class-E power amplifier through duty cycle.

    PubMed

    Chiu, Hung-Wei; Lu, Chien-Chi; Chuang, Jia-min; Lin, Wei-Tso; Lin, Chii-Wann; Kao, Ming-Chien; Lin, Mu-Lien

    2013-06-01

    This paper presents the design flow of two high-efficiency class-E amplifiers for the implantable electrical stimulation system. The implantable stimulator is a high-Q class-E driver that delivers a sine-wave pulsed radiofrequency (PRF) stimulation, which was verified to have a superior efficacy in pain relief to a square wave. The proposed duty-cycle-controlled class-E PRF driver designed with a high-Q factor has two operational modes that are able to achieve 100% DC-AC conversion, and involves only one switched series inductor and an unchanged parallel capacitor. The measured output amplitude under low-voltage (LV) mode using a 22% duty cycle was 0.98 V with 91% efficiency, and under high-voltage (HV) mode using a 47% duty cycle was 2.95 V with 92% efficiency. These modes were inductively controlled by a duty-cycle detector, which can detect the duty-cycle modulated signal generated from the external complementary low-Q class-E power amplifier (PA). The design methodology of the low-Q inductive interface for a non-50% duty cycle is presented. The experimental results exhibits that the 1.5-V PA that consumes DC power of 14.21 mW was able to deliver a 2.9-V sine wave to a 500 Ω load. The optimal 60% drain efficiency of the system from the PA to the load was obtained at a 10-mm coupling distance.

  16. The interplay between chromosome stability and cell cycle control explored through gene–gene interaction and computational simulation

    PubMed Central

    Frumkin, Jesse P.; Patra, Biranchi N.; Sevold, Anthony; Ganguly, Kumkum; Patel, Chaya; Yoon, Stephanie; Schmid, Molly B.; Ray, Animesh

    2016-01-01

    Chromosome stability models are usually qualitative models derived from molecular-genetic mechanisms for DNA repair, DNA synthesis, and cell division. While qualitative models are informative, they are also challenging to reformulate as precise quantitative models. In this report we explore how (A) laboratory experiments, (B) quantitative simulation, and (C) seriation algorithms can inform models of chromosome stability. Laboratory experiments were used to identify 19 genes that when over-expressed cause chromosome instability in the yeast Saccharomyces cerevisiae. To better understand the molecular mechanisms by which these genes act, we explored their genetic interactions with 18 deletion mutations known to cause chromosome instability. Quantitative simulations based on a mathematical model of the cell cycle were used to predict the consequences of several genetic interactions. These simulations lead us to suspect that the chromosome instability genes cause cell-cycle perturbations. Cell-cycle involvement was confirmed using a seriation algorithm, which was used to analyze the genetic interaction matrix to reveal an underlying cyclical pattern. The seriation algorithm searched over 1014 possible arrangements of rows and columns to find one optimal arrangement, which correctly reflects events during cell cycle phases. To conclude, we illustrate how the molecular mechanisms behind these cell cycle events are consistent with established molecular interaction maps. PMID:27530428

  17. The interplay between chromosome stability and cell cycle control explored through gene-gene interaction and computational simulation.

    PubMed

    Frumkin, Jesse P; Patra, Biranchi N; Sevold, Anthony; Ganguly, Kumkum; Patel, Chaya; Yoon, Stephanie; Schmid, Molly B; Ray, Animesh

    2016-09-30

    Chromosome stability models are usually qualitative models derived from molecular-genetic mechanisms for DNA repair, DNA synthesis, and cell division. While qualitative models are informative, they are also challenging to reformulate as precise quantitative models. In this report we explore how (A) laboratory experiments, (B) quantitative simulation, and (C) seriation algorithms can inform models of chromosome stability. Laboratory experiments were used to identify 19 genes that when over-expressed cause chromosome instability in the yeast Saccharomyces cerevisiae To better understand the molecular mechanisms by which these genes act, we explored their genetic interactions with 18 deletion mutations known to cause chromosome instability. Quantitative simulations based on a mathematical model of the cell cycle were used to predict the consequences of several genetic interactions. These simulations lead us to suspect that the chromosome instability genes cause cell-cycle perturbations. Cell-cycle involvement was confirmed using a seriation algorithm, which was used to analyze the genetic interaction matrix to reveal an underlying cyclical pattern. The seriation algorithm searched over 10(14) possible arrangements of rows and columns to find one optimal arrangement, which correctly reflects events during cell cycle phases. To conclude, we illustrate how the molecular mechanisms behind these cell cycle events are consistent with established molecular interaction maps. PMID:27530428

  18. aPKC phosphorylates p27Xic1, providing a mechanistic link between apicobasal polarity and cell-cycle control.

    PubMed

    Sabherwal, Nitin; Thuret, Raphael; Lea, Robert; Stanley, Peter; Papalopulu, Nancy

    2014-12-01

    During the development of the nervous system, apicobasally polarized stem cells are characterized by a shorter cell cycle than nonpolar progenitors, leading to a lower differentiation potential of these cells. However, how polarization might be directly linked to the kinetics of the cell cycle is not understood. Here, we report that apicobasally polarized neuroepithelial cells in Xenopus laevis have a shorter cell cycle than nonpolar progenitors, consistent with mammalian systems. We show that the apically localized serine/threonine kinase aPKC directly phosphorylates an N-terminal site of the cell-cycle inhibitor p27Xic1 and reduces its ability to inhibit the cyclin-dependent kinase 2 (Cdk2), leading to shortening of G1 and S phases. Overexpression of activated aPKC blocks the neuronal differentiation-promoting activity of p27Xic1. These findings provide a direct mechanistic link between apicobasal polarity and the cell cycle, which may explain how proliferation is favored over differentiation in polarized neural stem cells.

  19. The Gene Targeting Approach of Small Fragment Homologous Replacement (SFHR) Alters the Expression Patterns of DNA Repair and Cell Cycle Control Genes

    PubMed Central

    Pierandrei, Silvia; Luchetti, Andrea; Sanchez, Massimo; Novelli, Giuseppe; Sangiuolo, Federica; Lucarelli, Marco

    2016-01-01

    Cellular responses and molecular mechanisms activated by exogenous DNA that invades cells are only partially understood. This limits the practical use of gene targeting strategies. Small fragment homologous replacement (SFHR) uses a small exogenous wild-type DNA fragment to restore the endogenous wild-type sequence; unfortunately, this mechanism has a low frequency of correction. In this study, we used a mouse embryonic fibroblast cell line with a stably integrated mutated gene for enhanced green fluorescence protein. The restoration of a wild-type sequence can be detected by flow cytometry analysis. We quantitatively analyzed the expression of 84 DNA repair genes and 84 cell cycle control genes. Peculiar temporal gene expression patterns were observed for both pathways. Different DNA repair pathways, not only homologous recombination, as well as the three main cell cycle checkpoints appeared to mediate the cellular response. Eighteen genes were selected as highly significant target/effectors of SFHR. We identified a wide interconnection between SFHR, DNA repair, and cell cycle control. Our results increase the knowledge of the molecular mechanisms involved in cell invasion by exogenous DNA and SFHR. Specific molecular targets of both the cell cycle and DNA repair machineries were selected for manipulation to enhance the practical application of SFHR. PMID:27045208

  20. Carbonate and lignite cycles in the Ptolemais Basin: Orbital control and suborbital variability (Late Neogene, northern Greece)

    NASA Astrophysics Data System (ADS)

    Weber, M. E.; Tougiannidis, N.; Ricken, W.; Rolf, C.; Kleineder, M.; Bertram, N.; Antoniadis, P.

    2009-04-01

    ), assuming that the lignite phase is associated with maximum temperature and humidity. The reason to apply the tuning was primarily to obtain a better temporal control on the cyclicity documented in the suborbital frequency band. These higher-frequency variations provide a significant contribution and visually resemble those that have been documented for the Greenland Ice Sheet during the last glacial cycle. Future goals of our work include the establishment of possible teleconnections to other parts of the global climate system. We would like to evaluate (i) how the aridification of the Messinian salinity crisis affected the Upper Miocene limnic record, (ii) why the lignite production was enhanced during the warm Lower Pliocene and how the link to the warm global climate might have been created, and (iii) whether the massive northern hemisphere glaciation during the Upper Pliocene might have contributed to the termination of lignite formation in the Ptolemais Basin.

  1. Refractory Materials for Flame Deflector Protection System Corrosion Control: Flame Deflector Protection System Life Cycle Cost Analysis Report

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Coffman, Brekke E.; Kolody, Mark R.; Curran, Jerome P.; Trejo, David; Reinschmidt, Ken; Kim, Hyung-Jin

    2009-01-01

    A 20-year life cycle cost analysis was performed to compare the operational life cycle cost, processing/turnaround timelines, and operations manpower inspection/repair/refurbishment requirements for corrosion protection of the Kennedy Space Center launch pad flame deflector associated with the existing cast-in-place materials and a newer advanced refractory ceramic material. The analysis compared the estimated costs of(1) continuing to use of the current refractory material without any changes; (2) completely reconstructing the flame trench using the current refractory material; and (3) completely reconstructing the flame trench with a new high-performance refractory material. Cost estimates were based on an analysis of the amount of damage that occurs after each launch and an estimate of the average repair cost. Alternative 3 was found to save $32M compared to alternative 1 and $17M compared to alternative 2 over a 20-year life cycle.

  2. Diurnal and menstrual cycles in body temperature are regulated differently: a 28-day ambulatory study in healthy women with thermal discomfort of cold extremities and controls.

    PubMed

    Kräuchi, Kurt; Konieczka, Katarzyna; Roescheisen-Weich, Corina; Gompper, Britta; Hauenstein, Daniela; Schoetzau, Andreas; Fraenkl, Stephan; Flammer, Josef

    2014-02-01

    Diurnal cycle variations in body-heat loss and heat production, and their resulting core body temperature (CBT), are relatively well investigated; however, little is known about their variations across the menstrual cycle under ambulatory conditions. The main purpose of this study was to determine whether menstrual cycle variations in distal and proximal skin temperatures exhibit similar patterns to those of diurnal variations, with lower internal heat conductance when CBT is high, i.e. during the luteal phase. Furthermore, we tested these relationships in two groups of women, with and without thermal discomfort of cold extremities (TDCE). In total, 19 healthy eumenorrheic women with regular menstrual cycles (28-32 days), 9 with habitual TDCE (ages 29 ± 1.5 year; BMI 20.1 ± 0.4) and 10 controls without these symptoms (CON: aged 27 ± 0.8 year; BMI 22.7 ± 0.6; p < 0.004 different to TDCE) took part in the study. Twenty-eight days continuous ambulatory skin temperature measurements of distal (mean of hands and feet) and proximal (mean of sternum and infraclavicular regions) skin regions, thighs, and calves were carried out under real-life, ambulatory conditions (i-Buttons® skin probes, sampling rate: 2.5 min). The distal minus proximal skin temperature gradient (DPG) provided a valuable measure for heat redistribution from the core to the shell, and, hence, for internal heat conduction. Additionally, basal body temperature was measured sublingually directly after waking up in bed. Mean diurnal amplitudes in skin temperatures increased from proximal to distal skin regions and the 24-h mean values were inversely related. TDCE compared to CON showed significantly lower hand skin temperatures and DPG during daytime. However, menstrual cycle phase did not modify these diurnal patterns, indicating that menstrual and diurnal cycle variations in skin temperatures reveal additive effects. Most striking was the finding that all measured skin

  3. Mineralogical Controls of Fault Healing in Natural and Simulated Gouges with Implications for Fault Zone Processes and the Seismic Cycle

    NASA Astrophysics Data System (ADS)

    Carpenter, B. M.; Ikari, M.; Marone, C.

    2011-12-01

    The frictional strength and stability of tectonic faults is determined by asperity contact processes, granular deformation, and fault zone fabric development. The evolution of grain-scale contact area during the seismic cycle likely exhibits significant control on overall fault stability by influencing frictional restrengthening, or healing, during the interseismic period, and the rate-dependence of sliding friction, which controls earthquake nucleation and the mode of fault slip. We report on laboratory experiments designed to explore the affect of mineralogy on fault healing. We conducted frictional shear experiments in a double-direct shear configuration at room temperature, 100% relative humidity, and a normal stress of 20 MPa. We used samples from a wide range of natural faults, including outcrop samples and core recovered during scientific drilling. Faults include: Alpine (New Zealand), Zuccale (Italy), Rocchetta (Italy), San Gregorio (California), Calaveras (California), Kodiak (Alaska), Nankai (Japan), Middle America Trench (Costa Rica), and San Andreas (California). To isolate the role of mineralogy, we also tested simulated fault gouges composed of talc, montmorillonite, biotite, illite, kaolinite, quartz, andesine, and granite. Frictional healing was measured at an accumulated shear strain of ~15 within the gouge layers. We conducted slide-hold-slide tests ranging from 3 to 3000 seconds. The main suite of experiments used a background shearing rate of 10 μm/s; these were augmented with sub-suites at 1 and 100 μm/s. We find that phyllosilicate-rich gouges (e.g. talc, montmorillonite, San Andreas Fault) show little to no healing over all hold times. We find the highest healing rates (β ≈ 0.01, Δμ per decade in time, s) in gouges from the Alpine and Rocchetta faults, with the rest of our samples falling into an intermediate range of healing rates. Nearly all gouges exhibit log-linear healing rates with the exceptions of San Andreas Fault gouge and

  4. Ammonia control in children with urea cycle disorders (UCDs); Phase 2 comparison of sodium phenylbutyrate and glycerol phenylbutyrate☆

    PubMed Central

    Lichter-Konecki, Uta; Diaz, G.A.; Merritt, J.L.; Feigenbaum, A.; Jomphe, C.; Marier, J.F.; Beliveau, M.; Mauney, J.; Dickinson, K.; Martinez, A.; Mokhtarani, M.; Scharschmidt, B.; Rhead, W.

    2016-01-01

    Twenty four hour ammonia profiles and correlates of drug effect were examined in a phase 2 comparison of sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB or HPN-100), an investigational drug being developed for urea cycle disorders (UCDs). Study Design Protocol HPN-100-005 involved open label fixed-sequence switch-over from the prescribed NaPBA dose to a PBA-equimolar GPB dose with controlled diet. After 7 days on NaPBA or GPB, subjects underwent 24-hour blood sampling for ammonia and drug metabolite levels as well as measurement of 24-hour urinary phenyacetylglutamine (PAGN). Adverse events (AEs), safety labs and triplicate ECGs were monitored. Results Eleven subjects (9 OTC, 1 ASS, 1 ASL) enrolled and completed the switch-over from NaPBA (mean dose=12.4 g/d or 322 mg/kg/d; range=198–476 mg/kg/d) to GPB (mean dose=10.8 mL or 0.284 mL/kg/d or 313 mg/kg/d; range = 192–449 mg/kg/d). Possibly-related AEs were reported in 2 subjects on NaPBA and 4 subjects on GPB. All were mild, except for one moderate AE of vomiting on GPB related to an intercurrent illness. No clinically significant laboratory or ECG changes were observed. Ammonia was lowest after overnight fast, peaked postprandially in the afternoon to early evening and varied widely over 24 h with occasional values >100 μmol/L without symptoms. Ammonia values were ~25% lower on GPB vs. NaPBA (p ≥ 0.1 for ITT and p<0.05 for per protocol population). The upper 95% confidence interval for the difference between ammonia on GPB vs. NaPBA in the ITT population (95% CI 0.575, 1.061; p = 0.102) was less than the predefined non-inferiority margin of 1.25 and less than 1.0 in the pre-defined per-protocol population (95% CI 0.516, 0.958; p<0.05). No statistically significant differences were observed in plasma phenylacetic acid and PAGN exposure during dosing with GPB vs. NaPBA, and the percentage of orally administered PBA excreted as PAGN (66% for GPB vs. 69% for NaPBA) was very similar. GPB and Na

  5. A homolog of the cell cycle control protein p34cdc2 participates in the division cycle of Chlamydomonas, and a similar protein is detectable in higher plants and remote taxa.

    PubMed Central

    John, P C; Sek, F J; Lee, M G

    1989-01-01

    We investigated plant cell division by testing for the presence and involvement in progress through the division cycle of the protein p34cdc2, a key participant in division control in other eukaryotes. A protein of the same m(r) 34,000 has structural similarity indicated by its reaction with three sorts of antibody raised against (1) cell division-specific regions within a 16-amino acid internal sequence that is perfectly conserved in p34cdc2 from all known sources, (2) the carboxy-terminal 127 amino acids of human p34cdc2 linked to beta-galactosidase, and (3) whole p34cdc2 of fission yeast. Participation of p34 in the division cycle of the green plant Chlamydomonas is indicated by phosphorylation of the protein only in proliferating cells. There is a consistent fivefold increase relative to other proteins when cells become committed to division and a maximum of phosphorylation at the time of nuclear division under conditions that alter by twofold the time of these events. A p34 protein is detectable in oats and Arabidopsis and in remote taxa, including red and brown algae. We conclude that the plant kingdom shares a division control involving p34cdc2 that was probably established in the common ancestral eukaryote prior to divergence of any of the major eukaryote taxa. PMID:2535538

  6. Effect of inter-cycle interval on oocyte production in humans in the presence of the weak androgen DHEA and follicle stimulating hormone: a case-control study

    PubMed Central

    2014-01-01

    Background In various animal models androgens have been demonstrated to enhance follicle stimulating hormone (FSH) activity on granulosa cells during small growing follicle stages. To assess whether similar synergism may also exist in humans we investigated women on androgen (dehydroepiandrosterone, DHEA) supplementation with varying concomitant FSH exposure. Methods In a case controlled cohort study we determine if time interval between IVF cycles of IVF treatment with FSH had an effect on ovarian response to ovulation induction in women supplemented with DHEA. Among 85 women with known low functional ovarian reserve (LFOR), supplemented with DHEA, and undergoing at least 3 consecutive IVF cycles, 68 demonstrated short (<120 days) intervals between repeated cycles (Group 1) and were, therefore, considered to have consistent FSH exposure. In contrast 17 women (Group 2) demonstrated long (> = 120 days) intervals between repeated cycles and, therefore, were considered to demonstrate inconsistent FSH exposure. Trends in oocyte yields were compared between these groups, utilizing mixed model repeated measures ANOVA, adjusted for initial age and FSH dose. Results Only women in Group I demonstrated a linear increase in oocyte yields across their three cycles of treatments (F = 7.92; df 1, 68.6; p = 0.017). Moreover, the analysis revealed a significant interaction between the two patient groups and cycle number for retrieved oocytes (F = 6.32, df = 2, 85.9, p = 0.003). Conclusions This study offers preliminary confirmatory evidence that repeated short interval exposure to androgens in combination with FSH improves human FOR. A higher level of evidence will require prospectively randomized studies. PMID:25048047

  7. Evaluating the impacts of new walking and cycling infrastructure on carbon dioxide emissions from motorized travel: a controlled longitudinal study

    PubMed Central

    Brand, Christian; Goodman, Anna; Ogilvie, David

    2015-01-01

    Walking and cycling is widely assumed to substitute for at least some motorized travel and thereby reduce energy use and carbon dioxide (CO2) emissions. While the evidence suggests that a supportive built environment may be needed to promote walking and cycling, it is unclear whether and how interventions in the built environment that attract walkers and cyclists may reduce transport CO2 emissions. Our aim was therefore to evaluate the effects of providing new infrastructure for walking and cycling on CO2 emissions from motorised travel. A cohort of 1849 adults completed questionnaires at baseline (2010) and one-year follow-up (2011), before and after the construction of new high-quality routes provided as part of the Sustrans Connect2 programme in three UK municipalities. A second cohort of 1510 adults completed questionnaires at baseline and two-year follow-up (2012). The participants reported their past-week travel behaviour and car characteristics from which CO2 emissions by mode and purpose were derived using methods described previously. A set of exposure measures of proximity to and use of the new routes were derived. Overall transport CO2 emissions decreased slightly over the study period, consistent with a secular trend in the case study regions. As found previously the new infrastructure was well used at one- and two-year follow-up, and was associated with population-level increases in walking, cycling and physical activity at two-year follow-up. However, these effects did not translate into sizeable CO2 effects as neither living near the infrastructure nor using it predicted changes in CO2 emissions from motorised travel, either overall or disaggregated by journey purpose. This lack of a discernible effect on travel CO2 emissions are consistent with an interpretation that some of those living nearer the infrastructure may simply have changed where they walked or cycled, while others may have walked or cycled more but few, if any, may have substituted

  8. Knockdown of Sec8 promotes cell-cycle arrest at G1/S phase by inducing p21 via control of FOXO proteins.

    PubMed

    Tanaka, Toshiaki; Iino, Mituyoshi

    2014-02-01

    p21(Cip1) protein inhibits the activity of cyclins at the G(1) checkpoint and influences transition of cells from the G(1) to the S phase of the cell cycle. Moreover, expression of members of the FOXO family (active form of forkhead transcription factors of the O class) in dividing cells promotes cell-cycle arrest at the G(1)/S boundary via regulation of p21(Cip1). Recently, the exocyst complex, including Sec8, has been implicated in various roles independent of its role in secretion, such as cell migration, invadopodia formation, cytokinesis, glucose uptake and neural development. Given the essential roles of the exocyst complex in cellular and developmental processes, disruption of its function may be involved in various diseases such as cancer, diabetes and neuronal disorders. However, the relationship between Sec8 and the cell cycle remains to be elucidated. In this study, knockdown of Sec8 inhibited cell growth and promoted cell-cycle arrest at the G(1)/S phase by control of p21 expression and retinoblastoma protein phosphorylation. Furthermore, Sec8 regulated FOXO family proteins via ubiquitin-proteasome degradation by regulating the expression of the murine double minute 2 (Mdm2) protein but not S-phase kinase-associated protein 2 (Skp2).

  9. Prevention of multiple pregnancies in couples with unexplained or mild male subfertility: randomised controlled trial of in vitro fertilisation with single embryo transfer or in vitro fertilisation in modified natural cycle compared with intrauterine insemination with controlled ovarian hyperstimulation

    PubMed Central

    Bensdorp, A J; Tjon-Kon-Fat, R I; Bossuyt, P M M; Koks, C A M; Oosterhuis, G J E; Hoek, A; Hompes, P G A; Broekmans, F J M; Verhoeve, H R; de Bruin, J P; van Golde, R; Repping, S; Cohlen, B J; Lambers, M D A; van Bommel, P F; Slappendel, E; Perquin, D; Smeenk, J M; Pelinck, M J; Gianotten, J; Hoozemans, D A; Maas, J W M; Eijkemans, M J C; van der Veen, F; Mol, B W J

    2015-01-01

    Objectives To compare the effectiveness of in vitro fertilisation with single embryo transfer or in vitro fertilisation in a modified natural cycle with that of intrauterine insemination with controlled ovarian hyperstimulation in terms of a healthy child. Design Multicentre, open label, three arm, parallel group, randomised controlled non-inferiority trial. Setting 17 centres in the Netherlands. Participants Couples seeking fertility treatment after at least 12 months of unprotected intercourse, with the female partner aged between 18 and 38 years, an unfavourable prognosis for natural conception, and a diagnosis of unexplained or mild male subfertility. Interventions Three cycles of in vitro fertilisation with single embryo transfer (plus subsequent cryocycles), six cycles of in vitro fertilisation in a modified natural cycle, or six cycles of intrauterine insemination with ovarian hyperstimulation within 12 months after randomisation. Main outcome measures The primary outcome was birth of a healthy child resulting from a singleton pregnancy conceived within 12 months after randomisation. Secondary outcomes were live birth, clinical pregnancy, ongoing pregnancy, multiple pregnancy, time to pregnancy, complications of pregnancy, and neonatal morbidity and mortality Results 602 couples were randomly assigned between January 2009 and February 2012; 201 were allocated to in vitro fertilisation with single embryo transfer, 194 to in vitro fertilisation in a modified natural cycle, and 207 to intrauterine insemination with controlled ovarian hyperstimulation. Birth of a healthy child occurred in 104 (52%) couples in the in vitro fertilisation with single embryo transfer group, 83 (43%) in the in vitro fertilisation in a modified natural cycle group, and 97 (47%) in the intrauterine insemination with controlled ovarian hyperstimulation group. This corresponds to a risk, relative to intrauterine insemination with ovarian hyperstimulation, of 1.10 (95% confidence interval

  10. Differentiated influence of off-road and on-road cycling practice on balance control and the related-neurosensory organization.

    PubMed

    Lion, Alexis; Gauchard, Gérome C; Deviterne, Dominique; Perrin, Philippe P

    2009-08-01

    This study aimed to determine the sensorimotor strategies privileged by mountain bikers (MTB) and road cyclists (RC) for balance control. Twenty-four MTB and 24 RC (off-road Olympics, world, continental and national champions, Tour-de-France participants, on-road world cup race winner) volunteered to answer a questionnaire about the characteristics of cycling practice and perform a sensory organization test, aiming to evaluate balance control in 6 different sensory situations based upon visual and support surface perturbations (C1(ES) to C6(ES)). RC balance performances were better than those of MTB both during quiet stance eyes opened (C1(ES), p=0.011) and when only somatosensory information is disrupted (C4(ES), p=0.039), highlighting a higher use of vision to control balance in RC. Moreover, a positive correlation was shown in the whole population (MTB+RC) between the visual ratio (R(VIS)=C4(ES)/C1(ES)) and the proportion of riding distance of on-road cycling (rho=0.28, p=0.054). In MTB, the use of proprioception (somatosensory ratio: R(SOM)=C2(ES(eyes closed))/C1(ES)) was increased by a higher intensity of off-road cycling (rho=0.49, p=0.018) and that of vision (R(VIS)) by a higher intensity of on-road cycling (rho=0.41, p=0.048). The difference in sensory organization between MTB and RC could be explained by adaptive processes elaborated from environmental stimulations and technical specificities of these disciplines.

  11. Designing adaptive integral sliding mode control for heart rate regulation during cycle-ergometer exercise using bio-feedback.

    PubMed

    Argha, Ahmadreza; Su, Steven W; Nguyen, Hung; Celler, Branko G

    2015-01-01

    This paper considers our developed control system which aims to regulate the exercising subjects' heart rate (HR) to a predefined profile. The controller would be an adaptive integral sliding mode controller. Here it is assumed that the controller commands are interpreted as biofeedback auditory commands. These commands can be heard and implemented by the exercising subject as a part of the control-loop. However, transmitting a feedback signal while the pedals are not in the appropriate position to efficiently exert force may lead to a cognitive disengagement of the user from the feedback controller. To address this problem this paper will employ a different form of control system regarding as "actuator-based event-driven control system". This paper will claim that the developed event-driven controller makes it possible to effectively regulate HR to a predetermined HR profile.

  12. Outcomes of Intracytoplasmic Sperm Injection Cycles for Complete Teratozoospermia: A Case-Control Study Using Paired Sibling Oocytes

    PubMed Central

    Pereira, Nigel; Neri, Queenie V.; Lekovich, Jovana P.; Spandorfer, Steven D.; Palermo, Gianpiero D.; Rosenwaks, Zev

    2015-01-01

    Objective. To investigate the outcomes of intracytoplasmic sperm injection (ICSI) cycles where sibling oocytes from a single donor were split between two recipients based on strict sperm morphology. Methods. Retrospective cohort study. All ICSI cycles had one donor's oocytes split between two recipients in a 1 : 1 ratio based on strict sperm morphology, that is, one male partner had morphology of 0% and the other had morphology of >1%. Fertilization, positive hCG, clinical pregnancy, spontaneous miscarriage, and live birth rates of the aforementioned groups were compared. Results. The baseline characteristics of the two groups (n = 103), including semen parameters of the male partners, were comparable. There was no difference in the fertilization rates when comparing the 0% group to the >1% group (78.7% versus 81.6%; P = 0.66). The overall positive hCG, clinical pregnancy, spontaneous miscarriage, and live birth rates for the 0% group were 61.2%, 49.5%, 10.7%, and 38.8%, respectively. The corresponding rates in the >1% group were positive hCG (63.1%), clinical pregnancy (55.3%), spontaneous miscarriage (7.77%), and live birth (46.6%). Conclusions. The fertilization and pregnancy outcomes of ICSI cycles for strict sperm morphology of 0% versus morphology of >1% are equivalent. These results can provide reassurance to couples undergoing ICSI for severe teratospermia. PMID:26839883

  13. Long Noncoding RNA MALAT1 Controls Cell Cycle Progression by Regulating the Expression of Oncogenic Transcription Factor B-MYB

    PubMed Central

    Tripathi, Vidisha; Shen, Zhen; Chakraborty, Arindam; Giri, Sumanprava; Freier, Susan M.; Wu, Xiaolin; Zhang, Yongqing; Gorospe, Myriam; Prasanth, Supriya G.; Lal, Ashish; Prasanth, Kannanganattu V.

    2013-01-01

    The long noncoding MALAT1 RNA is upregulated in cancer tissues and its elevated expression is associated with hyper-proliferation, but the underlying mechanism is poorly understood. We demonstrate that MALAT1 levels are regulated during normal cell cycle progression. Genome-wide transcriptome analyses in normal human diploid fibroblasts reveal that MALAT1 modulates the expression of cell cycle genes and is required for G1/S and mitotic progression. Depletion of MALAT1 leads to activation of p53 and its target genes. The cell cycle defects observed in MALAT1-depleted cells are sensitive to p53 levels, indicating that p53 is a major downstream mediator of MALAT1 activity. Furthermore, MALAT1-depleted cells display reduced expression of B-MYB (Mybl2), an oncogenic transcription factor involved in G2/M progression, due to altered binding of splicing factors on B-MYB pre-mRNA and aberrant alternative splicing. In human cells, MALAT1 promotes cellular proliferation by modulating the expression and/or pre-mRNA processing of cell cycle–regulated transcription factors. These findings provide mechanistic insights on the role of MALAT1 in regulating cellular proliferation. PMID:23555285

  14. G1/S Inhibitors and the SWI/SNF Complex Control Cell-Cycle Exit during Muscle Differentiation.

    PubMed

    Ruijtenberg, Suzan; van den Heuvel, Sander

    2015-07-16

    The transition from proliferating precursor cells to post-mitotic differentiated cells is crucial for development, tissue homeostasis, and tumor suppression. To study cell-cycle exit during differentiation in vivo, we developed a conditional knockout and lineage-tracing system for Caenorhabditis elegans. Combined lineage-specific gene inactivation and genetic screening revealed extensive redundancies between previously identified cell-cycle inhibitors and the SWI/SNF chromatin-remodeling complex. Muscle precursor cells missing either SWI/SNF or G1/S inhibitor function could still arrest cell division, while simultaneous inactivation of these regulators caused continued proliferation and a C. elegans tumor phenotype. Further genetic analyses support that SWI/SNF acts in concert with hlh-1 MyoD, antagonizes Polycomb-mediated transcriptional repression, and suppresses cye-1 Cyclin E transcription to arrest cell division of muscle precursors. Thus, SWI/SNF and G1/S inhibitors provide alternative mechanisms to arrest cell-cycle progression during terminal differentiation, which offers insight into the frequent mutation of SWI/SNF genes in human cancers.

  15. CDK2-dependent phosphorylation of Suv39H1 is involved in control of heterochromatin replication during cell cycle progression

    PubMed Central

    Park, Su Hyung; Yu, Seung Eun; Chai, Young Gyu; Jang, Yeun Kyu

    2014-01-01

    Although several studies have suggested that the functions of heterochromatin regulators may be regulated by post-translational modifications during cell cycle progression, regulation of the histone methyltransferase Suv39H1 is not fully understood. Here, we demonstrate a direct link between Suv39H1 phosphorylation and cell cycle progression. We show that CDK2 phosphorylates Suv39H1 at Ser391 and these phosphorylation levels oscillate during the cell cycle, peaking at S phase and maintained during S-G2-M phase. The CDK2-mediated phosphorylation of Suv39H1 at Ser391 results in preferential dissociation from chromatin. Furthermore, phosphorylation-mediated dissociation of Suv39H1 from chromatin causes an enhanced occupancy of JMJD2A histone demethylase on heterochromatin and alterations in inactive histone marks. Overexpression of phospho-mimic Suv39H1 induces early replication of heterochromatin, suggesting the importance of Suv39H1 phosphorylation in the replication of heterochromatin. Moreover, overexpression of phospho-defective Suv39H1 caused altered replication timing of heterochromatin and increases sensitivity to replication stress. Collectively, our data suggest that phosphorylation-mediated modulation of Suv39H1-chromatin association may be an initial step in heterochromatin replication. PMID:24728993

  16. Investigation of plant control strategies for the supercritical C0{sub 2}Brayton cycle for a sodium-cooled fast reactor using the plant dynamics code.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J.

    2011-04-12

    The development of a control strategy for the supercritical CO{sub 2} (S-CO{sub 2}) Brayton cycle has been extended to the investigation of alternate control strategies for a Sodium-Cooled Fast Reactor (SFR) nuclear power plant incorporating a S-CO{sub 2} Brayton cycle power converter. The SFR assumed is the 400 MWe (1000 MWt) ABR-1000 preconceptual design incorporating metallic fuel. Three alternative idealized schemes for controlling the reactor side of the plant in combination with the existing automatic control strategy for the S-CO{sub 2} Brayton cycle are explored using the ANL Plant Dynamics Code together with the SAS4A/SASSYS-1 Liquid Metal Reactor (LMR) Analysis Code System coupled together using the iterative coupling formulation previously developed and implemented into the Plant Dynamics Code. The first option assumes that the reactor side can be ideally controlled through movement of control rods and changing the speeds of both the primary and intermediate coolant system sodium pumps such that the intermediate sodium flow rate and inlet temperature to the sodium-to-CO{sub 2} heat exchanger (RHX) remain unvarying while the intermediate sodium outlet temperature changes as the load demand from the electric grid changes and the S-CO{sub 2} cycle conditions adjust according to the S-CO{sub 2} cycle control strategy. For this option, the reactor plant follows an assumed change in load demand from 100 to 0 % nominal at 5 % reduction per minute in a suitable fashion. The second option allows the reactor core power and primary and intermediate coolant system sodium pump flow rates to change autonomously in response to the strong reactivity feedbacks of the metallic fueled core and assumed constant pump torques representing unchanging output from the pump electric motors. The plant behavior to the assumed load demand reduction is surprising close to that calculated for the first option. The only negative result observed is a slight increase in the intermediate

  17. Controllable synthesis of high-rate and long cycle-life Na3V2(PO4)3 for sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Hui; Wu, Chuan; Bai, Ying; Wu, Feng; Wang, Muzi

    2016-09-01

    Structural and morphological control is an effective approach for improvement of electrochemical performance in rechargeable batteries. In this paper, three different morphological Na3V2(PO4)3 (irregular shaped, the porous sponge-like and plate like) were successfully prepared through controlling the amount of oxalic acid by a simple two-step reduction method. It is found that the amount of oxalic acid has vital impacts on the morphology of Na3V2(PO4)3; moreover, the morphological evolution and formation mechanism are proposed based on the reactions of different amount of oxalic acid occurring in the two-step reduction process. The excellent electrochemical performances of the porous sponge-like Na3V2(PO4)3 are attributed to the unique morphology. The initial capacity of the porous sponge-like Na3V2(PO4)3 is 101.77 mAh g-1 at 30 C; after 700 cycles, it remains as high as 89.28 mAh g-1 with only 12% capacity loss. When the current density increases to 50 C and 70 C, the capacity retentions of 81% after 600 cycles, and 92.5% after 500 cycles are achieved, respectively.

  18. Geochemical and hydrodynamic controls on arsenic and trace metal cycling in a seasonally stratified US sub-tropical reservoir

    SciTech Connect

    Brandenberger, Jill M.; Louchouarn, Patrick; Herbert, Bruce; Tissot, Philippe

    2004-10-01

    The phase distribution of trace metals and oxyanions was investigated within a South Texas watershed hosting a high density of surface uranium mine pits and tailings. The objectives of the study were to evaluate the potential impact of these old uranium mining sites on the watershed with particular emphasis on spatial and temporal changes in water quality of a reservoir that serves as the major source of freshwater to a population of {approx} 350,000 people in the region. A livestock pond, bordered by uranium mine tailings, was used as a model case-study site to evaluate the cycling of uranium mine-derived oxyanions under changing redox conditions. Although the pond showed seasonal thermal and chemical stratification, geochemical cycling of metals was limited to Co and Pb, which seemed to be mostly associated with redox cycling of Mn mineral phases, and U, which suggested reductive precipitation in the ponds hypolimnion. Uranium levels, however, were too low to support strong inputs from th e tailings into the water column of the pond. The strong relations observed between particulate Cr, Cs, V and Fe suggest that these metals are associated with a stable particulate phase (probably allochthonous aluminosilicates) enriched in unreactive iron. This observation is supported by a parallel relationship in sediments collected across a broad range of sediment depositional processed (and histories) in the basin. Arsenic, though selectively enriched in the ponds water column, remained stable and mostly in solution throughout the depth of the profile and showed no sign of geochemical cycling or interaction with Fe-rich particles. We found no evidence of anthropogenic impacts of U mines beyond the purely local scale. Arsenic does decrease in concentration downstream of uranium mining sites but its presence within the Nueces drainage basin is related to interactions between surface and ground waters with uranium-rich geological formations rather than long-scale transport of

  19. DACH1 regulates cell cycle progression of myeloid cells through the control of cyclin D, Cdk 4/6 and p21{sup Cip1}

    SciTech Connect

    Lee, Jae-Woong; Kim, Hyeng-Soo; Kim, Seonggon; Hwang, Junmo; Kim, Young Hun; Lim, Ga Young; Sohn, Wern-Joo; Yoon, Suk-Ran; Kim, Jae-Young; Park, Tae Sung; Park, Kwon Moo; Ryoo, Zae Young; Lee, Sanggyu

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer DACH1 increases cyclin D, F and Cdk 1, 4, 6 in mouse myeloid progenitor cells. Black-Right-Pointing-Pointer The knockdown of DACH1 blocked the cell cycle progression of HL-60 cells. Black-Right-Pointing-Pointer The novel effect of DACH1 related with cell cycle regulation and leukemogenesis. -- Abstract: The cell-fate determination factor Dachshund, a component of the Retinal Determination Gene Network (RDGN), has a role in breast tumor proliferation through the repression of cyclin D1 and several key regulators of embryonic stem cell function, such as Nanog and Sox2. However, little is known about the role of DACH1 in a myeloid lineage as a cell cycle regulator. Here, we identified the differential expression levels of extensive cell cycle regulators controlled by DACH1 in myeloid progenitor cells. The forced expression of DACH1 induced p27{sup Kip1} and repressed p21{sup Cip1}, which is a pivotal characteristic of the myeloid progenitor. Furthermore, DACH1 significantly increased the expression of cyclin D1, D3, F, and Cdk 1, 4, and 6 in myeloid progenitor cells. The knockdown of DACH1 blocked the cell cycle progression of HL-60 promyeloblastic cells through the decrease of cyclin D1, D3, F, and Cdk 1, 4, and 6 and increase in p21{sup Cip1}, which in turn decreased the phosphorylation of the Rb protein. The expression of Sox2, Oct4, and Klf4 was significantly up-regulated by the forced expression of DACH1 in mouse myeloid progenitor cells.

  20. A temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

    NASA Astrophysics Data System (ADS)

    Bu, Minqiang; Perch-Nielsen, Ivan R.; Sørensen, Karen S.; Skov, Julia; Sun, Yi; Duong Bang, Dang; Pedersen, Michael E.; Hansen, Mikkel F.; Wolff, Anders

    2013-07-01

    We present a temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with an external heater and a temperature sensor. The method employs optimized temperature overshooting and undershooting steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature-dependent fluorescence signal from Rhodamine B. The method was validated with the PCR amplification of mecA gene (162 bp) from methicillin-resistant Staphylococcus aureus bacterium (MRSA), where the time for 30 cycles was reduced from 50 min (without over- and undershooting) to 20 min.

  1. Menstrual Cycle

    MedlinePlus

    ... Pregnancy This information in Spanish ( en español ) The menstrual cycle Day 1 starts with the first day of ... drop around Day 25 . This signals the next menstrual cycle to begin. The egg will break apart and ...

  2. Biogeochemical Cycling

    NASA Technical Reports Server (NTRS)

    Bebout, Brad; Fonda, Mark (Technical Monitor)

    2002-01-01

    This lecture will introduce the concept of biogeochemical cycling. The roles of microbes in the cycling of nutrients, production and consumption of trace gases, and mineralization will be briefly introduced.

  3. Control of cell cycle by metabolites of prostaglandin D2 through a non-cAMP mediated mechanism

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.; Fukushima, M.

    1993-01-01

    The dehydration products of PGD2, 9-deoxy-9 prostaglandin D2(PGJ2), 9-deoxy-delta 9, delta 12, delta 13 dehydroprostaglandin D2 (delta 12 PGJ2), and PGA2 all contain an unsaturated cyclopentenone structure which is characteristic of prostaglandins which effectively inhibit cell growth. It has been suggested that the action of the inhibitory prostaglandins may be through a cAMP mechanism. In this study, we use S49 wild type (WT) and adenylate cyclase variant (cyc-) cells to show that PGD2 and PGJ2 are not acting via a cyclic AMP mechanism. First, the increase in cyclic AMP in wild type S-49 cells is not proportional to its effects on DNA synthesis. More importantly, when S-49 cyc- cells were exposed to PGJ2, the adenylate cyclase (cyc-) mutant had decreased DNA synthesis with no change in its nominal cAMP content. Short-term (2 hours or less) exposure of the cyc- cells to prostaglandin J2 caused an inhibition of DNA synthesis. PGJ2 caused cytolysis at high concentrations. Long-term exposure (>14 hrs) of the cells to PGJ2, delta 12PGJ2 or delta 12, delta 14PGJ2 caused a cell cycle arrest in G1 demonstrating a cell cycle specific mechanism of action for growth inhibition by naturally occurring biological products independent of cAMP.

  4. Stomatal controls on vegetation productivity and water cycling across the African continent in a warmer and CO2 enriched climate

    NASA Astrophysics Data System (ADS)

    Sato, H.; Kumagai, T.; Takahashi, A.; Katul, G. G.

    2014-12-01

    General Circulation Models (GCMs) forecast higher vapor pressure deficit (VPD) but unchanged relative humidity (RH) in future climates. A recent literature survey revealed some 50% of Earth System (ESMs) and Land Surface (LSMs) Models embedded within GCMs employ RH as an atmospheric aridity index when describing stomatal conductance (gs) while the remaining 50% employ VPD. Propagating the consequences of using RH or VPD in gs models on water cycling and vegetation productivity in future climates in one of the most vulnerable continents, the African continent, remains to be explored. Using process-based global dynamic vegetation model runs, changes in the hydrological cycle and concomitant vegetation productivity for a 21st century projected climate are conducted by altering only gs responses to VPD or RH while maintaining all other formulations unaltered. In the simulations under warming trend of the 21st century, both stomata functions of VPD and RH result in nearly identical changes in the geographic pattern of Gross Primary Production (GPP). However, continental total of GPP becomes bit larger for the VPD function than for the RH function. Transpiration rates becomes lower resulting in water-use-efficiency becoming higher by some 13% for the VPD function when compared to its RH counterpart.

  5. Abscisic Acid Participates in the Control of Cell Cycle Initiation Through Heme Homeostasis in the Unicellular Red Alga Cyanidioschyzon merolae.

    PubMed

    Kobayashi, Yuki; Ando, Hiroyuki; Hanaoka, Mitsumasa; Tanaka, Kan

    2016-05-01

    ABA is a phytohormone that is synthesized in response to abiotic stresses and other environmental changes, inducing various physiological responses. While ABA has been found in unicellular photosynthetic organisms, such as cyanobacteria and eukaryotic algae, its function in these organisms is poorly understood. Here, we found that ABA accumulated in the unicellular red alga Cyanidioschyzon merolae under conditions of salt stress and that the cell cycle G1/S transition was inhibited when ABA was added to the culture medium. A gene encoding heme-scavenging tryptophan-rich sensory protein-related protein (CmTSPO; CMS231C) was positively regulated by ABA, as in Arabidopsis, and CmTSPO bound heme in vitro. The intracellular content of total heme was increased by addition of ABA, but unfettered heme decreased, presumably due to scavenging by CmTSPO. The inhibition of DNA replication by ABA was negated by addition of heme to the culture medium. Thus, we propose a regulatory role for ABA and heme in algal cell cycle initiation. Finally, we found that a C. merolae mutant that is defective in ABA production was more susceptible to salt stress, indicating the importance of ABA to stress resistance in red algae. PMID:27044672

  6. A genomic multi-process survey of the machineries that control and link cell shape, microtubule organisation and cell cycle progression

    PubMed Central

    Geymonat, Marco; Bortfeld-Miller, Miriam; Walter, Thomas; Wagstaff, Laura; Piddini, Eugenia; Carazo Salas, Rafael E.

    2015-01-01

    SUMMARY Understanding cells as integrated systems requires that we systematically decipher how single genes affect multiple biological processes and how processes are functionally linked. Here, we used multi-process phenotypic profiling, combining high-resolution 3D confocal microscopy and multi-parametric image analysis, to simultaneously survey the fission yeast genome with respect to three key cellular processes: cell shape, microtubule organisation and cell cycle progression. We identify, validate and functionally annotate 262 genes controlling specific aspects of those processes. Of these 62% had not been linked to these processes before and 35% are implicated in multiple processes. Importantly, we identify a conserved role for DNA-damage responses in controlling microtubule stability. In addition, we investigate how the processes are functionally linked. We show unexpectedly that disruption of cell cycle progression does not necessarily impact on cell size control and that distinct aspects of cell shape regulate microtubules and vice-versa, identifying important systems-level links across these processes. PMID:25373780

  7. Carrier-envelope phase-tagged imaging of the controlled electron acceleration from SiO2 nanospheres in intense few-cycle laser fields

    NASA Astrophysics Data System (ADS)

    Zherebtsov, S.; Süßmann, F.; Peltz, C.; Plenge, J.; Betsch, K. J.; Znakovskaya, I.; Alnaser, A. S.; Johnson, N. G.; Kübel, M.; Horn, A.; Mondes, V.; Graf, C.; Trushin, S. A.; Azzeer, A.; Vrakking, M. J. J.; Paulus, G. G.; Krausz, F.; Rühl, E.; Fennel, T.; Kling, M. F.

    2012-07-01

    Waveform-controlled light fields offer the possibility of manipulating ultrafast electronic processes on sub-cycle timescales. The optical lightwave control of the collective electron motion in nanostructured materials is key to the design of electronic devices operating at up to petahertz frequencies. We have studied the directional control of the electron emission from 95 nm diameter SiO2 nanoparticles in few-cycle laser fields with a well-defined waveform. Projections of the three-dimensional (3D) electron momentum distributions were obtained via single-shot velocity-map imaging (VMI), where phase tagging allowed retrieving the laser waveform for each laser shot. The application of this technique allowed us to efficiently suppress background contributions in the data and to obtain very accurate information on the amplitude and phase of the waveform-dependent electron emission. The experimental data that are obtained for 4 fs pulses centered at 720 nm at different intensities in the range (1-4) × 1013 W cm-2 are compared to quasi-classical mean-field Monte-Carlo simulations. The model calculations identify electron backscattering from the nanoparticle surface in highly dynamical localized fields as the main process responsible for the energetic electron emission from the nanoparticles. The local field sensitivity of the electron emission observed in our studies can serve as a foundation for future research on propagation effects for larger particles and field-induced material changes at higher intensities.

  8. The late Silurian-Middle Devonian long-term eustatic cycle as a possible control on the global generic diversity dynamics of bivalves and gastropods

    NASA Astrophysics Data System (ADS)

    Ruban, Dmitry A.

    2013-09-01

    A long-term eustatic cycle (fall and subsequent rise of the global sea level) embraced the late Silurian-Middle Devonian time interval. Potentially, these sea-level changes could drive global biodiversity. The stratigraphic ranges of 204 bivalve genera and 279 gastropod genera included into the famous Sepkoski database allow reconstructing changes in the total diversity and the number of originations and extinctions of these important groups of marine benthic macro- -invertebrates during this interval. None of the recorded parameters coincided with the long-term global sea-level cycle. It cannot be not excluded, however, that the global sea-level changes did not affect the regions favourable for bivalve and gastropod radiation because of regional tectonic mechanisms; neither can it be excluded that the eustatic control persisted together with many other extrinsic and intrinsic controls. Interestingly, the generic diversity of gastropods increased together with a cooling trend, and vice versa. Additionally, the Ludlow, Eifelian, and Givetian biotic crises affected, probably, both fossil groups under study. There was also a coincidence of the relatively high bivalve generic diversity, initial radiation of gastropods and the entire biota, and the diversification of brachiopods with the Early Devonian global sea-level lowstand, and this may be interpreted as evidence of a certain eustatic control on the marine biodiversity.

  9. Use of a small molecule cell cycle inhibitor to control cell growth and improve specific productivity and product quality of recombinant proteins in CHO cell cultures

    PubMed Central

    Du, Zhimei; Treiber, David; McCarter, John D; Fomina-Yadlin, Dina; Saleem, Ramsey A; McCoy, Rebecca E; Zhang, Yuling; Tharmalingam, Tharmala; Leith, Matthew; Follstad, Brian D; Dell, Brad; Grisim, Brent; Zupke, Craig; Heath, Carole; Morris, Arvia E; Reddy, Pranhitha

    2015-01-01

    The continued need to improve therapeutic recombinant protein productivity has led to ongoing assessment of appropriate strategies in the biopharmaceutical industry to establish robust processes with optimized critical variables, that is, viable cell density (VCD) and specific productivity (product per cell, qP). Even though high VCD is a positive factor for titer, uncontrolled proliferation beyond a certain cell mass is also undesirable. To enable efficient process development to achieve consistent and predictable growth arrest while maintaining VCD, as well as improving qP, without negative impacts on product quality from clone to clone, we identified an approach that directly targets the cell cycle G1-checkpoint by selectively inhibiting the function of cyclin dependent kinases (CDK) 4/6 with a small molecule compound. Results from studies on multiple recombinant Chinese hamster ovary (CHO) cell lines demonstrate that the selective inhibitor can mediate a complete and sustained G0/G1 arrest without impacting G2/M phase. Cell proliferation is consistently and rapidly controlled in all recombinant cell lines at one concentration of this inhibitor throughout the production processes with specific productivities increased up to 110 pg/cell/day. Additionally, the product quality attributes of the mAb, with regard to high molecular weight (HMW) and glycan profile, are not negatively impacted. In fact, high mannose is decreased after treatment, which is in contrast to other established growth control methods such as reducing culture temperature. Microarray analysis showed major differences in expression of regulatory genes of the glycosylation and cell cycle signaling pathways between these different growth control methods. Overall, our observations showed that cell cycle arrest by directly targeting CDK4/6 using selective inhibitor compound can be utilized consistently and rapidly to optimize process parameters, such as cell growth, qP, and glycosylation profile in

  10. Forty years of control of the oestrous cycle in ruminants: progress made, unresolved problems and the potential impact of sperm encapsulation technology.

    PubMed

    Jöchle, W

    1993-01-01

    Pharmacological control of the oestrous cycle may, with or without sperm encapsulation, remain an indispensable part of any attempt to make artificial insemination available to the ranch-cattle industry. Of the current methods, those most likely to remain acceptable with regulatory agencies and to gain acceptance with industry are those involving the short-term use (7-10 days) of minimal effective doses of progestins (preferably progesterone) and the subsequent use of an analogue of prostaglandin F2 alpha. The use of microencapsulated sperm with a long lifespan would allow artificial insemination to be achieved without reference to the time when heat and ovulation may occur. PMID:9627721

  11. p53 and Cell Cycle Dependent Transcription of kinesin family member 23 (KIF23) Is Controlled Via a CHR Promoter Element Bound by DREAM and MMB Complexes

    PubMed Central

    Quaas, Marianne; Hoffmann, Saskia; Knörck, Arne; Gumhold, Catalina; Rother, Karen

    2013-01-01

    The microtubule-dependent molecular motor KIF23 (Kinesin family member 23) is one of two components of the centralspindlin complex assembled during late stages of mitosis. Formation of this complex is known as an essential step for cytokinesis. Here, we identified KIF23 as a new transcriptional target gene of the tumor suppressor protein p53. We showed that p53 reduces expression of KIF23 on the mRNA as well as the protein level in different cell types. Promoter reporter assays revealed that this repression results from downregulation of KIF23 promoter activity. CDK inhibitor p21WAF1/CIP1 was shown to be necessary to mediate p53-dependent repression. Furthermore, we identified the highly conserved cell cycle genes homology region (CHR) in the KIF23 promoter to be strictly required for p53-dependent repression as well as for cell cycle-dependent expression of KIF23. Cell cycle- and p53-dependent regulation of KIF23 appeared to be controlled by differential binding of DREAM and MMB complexes to the CHR element. With this study, we describe a new mechanism for transcriptional regulation of KIF23. Considering the strongly supporting function of KIF23 in cytokinesis, its p53-dependent repression may contribute to the prevention of uncontrolled cell growth. PMID:23650552

  12. p53 and cell cycle dependent transcription of kinesin family member 23 (KIF23) is controlled via a CHR promoter element bound by DREAM and MMB complexes.

    PubMed

    Fischer, Martin; Grundke, Inga; Sohr, Sindy; Quaas, Marianne; Hoffmann, Saskia; Knörck, Arne; Gumhold, Catalina; Rother, Karen

    2013-01-01

    The microtubule-dependent molecular motor KIF23 (Kinesin family member 23) is one of two components of the centralspindlin complex assembled during late stages of mitosis. Formation of this complex is known as an essential step for cytokinesis. Here, we identified KIF23 as a new transcriptional target gene of the tumor suppressor protein p53. We showed that p53 reduces expression of KIF23 on the mRNA as well as the protein level in different cell types. Promoter reporter assays revealed that this repression results from downregulation of KIF23 promoter activity. CDK inhibitor p21(WAF1/CIP1) was shown to be necessary to mediate p53-dependent repression. Furthermore, we identified the highly conserved cell cycle genes homology region (CHR) in the KIF23 promoter to be strictly required for p53-dependent repression as well as for cell cycle-dependent expression of KIF23. Cell cycle- and p53-dependent regulation of KIF23 appeared to be controlled by differential binding of DREAM and MMB complexes to the CHR element. With this study, we describe a new mechanism for transcriptional regulation of KIF23. Considering the strongly supporting function of KIF23 in cytokinesis, its p53-dependent repression may contribute to the prevention of uncontrolled cell growth.

  13. Host Cell Factor-1 Recruitment to E2F-bound and Cell Cycle Control Genes is Mediated by THAP11 and ZNF143

    PubMed Central

    Parker, J. Brandon; Yin, Hanwei; Vinckevicius, Aurimas; Chakravarti, Debabrata

    2014-01-01

    Summary Host cell factor-1 (HCF-1) is a metazoan transcriptional co-regulator essential for cell cycle progression and cell proliferation. Current models suggest a mechanism whereby HCF-1 functions as a direct co-regulator of E2F proteins, facilitating the expression of genes necessary for cell proliferation. In this report, we show that HCF-1 recruitment to numerous E2F-bound promoters is mediated by the concerted action of zinc finger transcription factors THAP11 and ZNF143, rather than E2F proteins directly. THAP11, ZNF143, and HCF-1 form a mutually dependent complex on chromatin, which is independent of E2F occupancy. Disruption of the THAP11/ZNF143/HCF-1 complex results in altered expression of cell cycle control genes and leads to reduced cell proliferation, cell cycle progression, and cell viability. These data establish a new model which suggests that a THAP11/ZNF143/HCF-1 complex is a critical component of the transcriptional regulatory network governing cell proliferation. PMID:25437553

  14. XIAO is involved in the control of organ size by contributing to the regulation of signaling and homeostasis of brassinosteroids and cell cycling in rice.

    PubMed

    Jiang, Yunhe; Bao, Liang; Jeong, So-Yoon; Kim, Seong-Ki; Xu, Caiguo; Li, Xianghua; Zhang, Qifa

    2012-05-01

    Organ size is determined by cell number and size, and involves two fundamental processes: cell proliferation and cell expansion. Although several plant hormones are known to play critical roles in shaping organ size by regulating the cell cycle, it is not known whether brassinosteroids (BRs) are also involved in regulating cell division. Here we identified a rice T-DNA insertion mutant for organ size, referred to as xiao, that displays dwarfism and erect leaves, typical BR-related phenotypes, together with reduced seed setting. XIAO is predicted to encode an LRR kinase. The small stature of the xiao mutant resulted from reduced organ sizes due to decreased cell numbers resulting from reduced cell division rate, as supported by the observed co-expression of XIAO with a number of genes involved in cell cycling. The xiao mutant displayed a tissue-specific enhanced BR response and greatly reduced BR contents at the whole-plant level. These results indicated that XIAO is a regulator of BR signaling and cell division. Thus, XIAO may provide a possible connection between BRs and cell-cycle regulation in controlling organ growth.

  15. Developmental Control of Cell-Cycle Compensation Provides a Switch for Patterned Mitosis at the Onset of Chordate Neurulation.

    PubMed

    Ogura, Yosuke; Sasakura, Yasunori

    2016-04-18

    During neurulation of chordate ascidians, the 11th mitotic division within the epidermal layer shows a posterior-to-anterior wave that is precisely coordinated with the unidirectional progression of the morphogenetic movement. Here we show that the first sign of this patterned mitosis is an asynchronous anterior-to-posterior S-phase length and that mitotic synchrony is reestablished by a compensatory asynchronous G2-phase length. Live imaging combined with genetic experiments demonstrated that compensatory G2-phase regulation requires transcriptional activation of the G2/M regulator cdc25 by the patterning genes GATA and AP-2. The downregulation of GATA and AP-2 at the onset of neurulation leads to loss of compensatory G2-phase regulation and promotes the transition to patterned mitosis. We propose that such developmentally regulated cell-cycle compensation provides an abrupt switch to spatially patterned mitosis in order to achieve the coordination between mitotic timing and morphogenesis.

  16. Fruiting Body Formation in Volvariella volvacea Can Occur Independently of Its MAT-A-Controlled Bipolar Mating System, Enabling Homothallic and Heterothallic Life Cycles

    PubMed Central

    Chen, Bingzhi; van Peer, Arend F.; Yan, Junjie; Li, Xiao; Xie, Bin; Miao, Juan; Huang, Qianhui; Zhang, Lei; Wang, Wei; Fu, Junsheng; Zhang, Xiang; Zhang, Xiaoyin; Hu, Fengli; Kong, Qingfang; Sun, Xianyun; Zou, Feng; Zhang, Hanxing; Li, Shaojie; Xie, Baogui

    2016-01-01

    Volvariella volvacea is an important crop in Southeast Asia, but erratic fruiting presents a serious challenge for its production and breeding. Efforts to explain inconsistent fruiting have been complicated by the multinucleate nature, typical lack of clamp connections, and an incompletely identified sexual reproductive system. In this study, we addressed the life cycle of V. volvacea using whole genome sequencing, cloning of MAT loci, karyotyping of spores, and fruiting assays. Microscopy analysis of spores had previously indicated the possible coexistence of heterothallic and homothallic life cycles. Our analysis of the MAT loci showed that only MAT-A, and not MAT-B, controlled heterokaryotization. Thus, the heterothallic life cycle was bipolar. Karyotyping of single spore isolates (SSIs) using molecular markers supported the existence of heterokaryotic spores. However, most SSIs were clearly not heterokaryotic, yet contained structural variation (SV) markers relating to both alleles of both parents. Heterokaryons from crossed, self-sterile homokaryons could produce fruiting bodies, agreeing with bipolar heterothallism. Meanwhile, some SSIs with two different MAT-A loci also produced fruiting bodies, which supported secondary homothallism. Next, SSIs that clearly contained only one MAT-A locus (homothallism) were also able to fruit, demonstrating that self-fertile SSIs were not, per definition, secondary homothallic, and that a third life cycle or genetic mechanism must exist. Finally, recombination between SV markers was normal, yet 10 out of 24 SV markers showed 1:2 or 1:3 distributions in the spores, and large numbers of SSIs contained doubled SV markers. This indicated selfish genes, and possibly partial aneuploidy. PMID:27194800

  17. Fruiting Body Formation in Volvariella volvacea Can Occur Independently of Its MAT-A-Controlled Bipolar Mating System, Enabling Homothallic and Heterothallic Life Cycles.

    PubMed

    Chen, Bingzhi; van Peer, Arend F; Yan, Junjie; Li, Xiao; Xie, Bin; Miao, Juan; Huang, Qianhui; Zhang, Lei; Wang, Wei; Fu, Junsheng; Zhang, Xiang; Zhang, Xiaoyin; Hu, Fengli; Kong, Qingfang; Sun, Xianyun; Zou, Feng; Zhang, Hanxing; Li, Shaojie; Xie, Baogui

    2016-01-01

    Volvariella volvacea is an important crop in Southeast Asia, but erratic fruiting presents a serious challenge for its production and breeding. Efforts to explain inconsistent fruiting have been complicated by the multinucleate nature, typical lack of clamp connections, and an incompletely identified sexual reproductive system. In this study, we addressed the life cycle of V. volvacea using whole genome sequencing, cloning of MAT loci, karyotyping of spores, and fruiting assays. Microscopy analysis of spores had previously indicated the possible coexistence of heterothallic and homothallic life cycles. Our analysis of the MAT loci showed that only MAT-A, and not MAT-B, controlled heterokaryotization. Thus, the heterothallic life cycle was bipolar. Karyotyping of single spore isolates (SSIs) using molecular markers supported the existence of heterokaryotic spores. However, most SSIs were clearly not heterokaryotic, yet contained structural variation (SV) markers relating to both alleles of both parents. Heterokaryons from crossed, self-sterile homokaryons could produce fruiting bodies, agreeing with bipolar heterothallism. Meanwhile, some SSIs with two different MAT-A loci also produced fruiting bodies, which supported secondary homothallism. Next, SSIs that clearly contained only one MAT-A locus (homothallism) were also able to fruit, demonstrating that self-fertile SSIs were not, per definition, secondary homothallic, and that a third life cycle or genetic mechanism must exist. Finally, recombination between SV markers was normal, yet 10 out of 24 SV markers showed 1:2 or 1:3 distributions in the spores, and large numbers of SSIs contained doubled SV markers. This indicated selfish genes, and possibly partial aneuploidy. PMID:27194800

  18. Dynamic Modeling and Control of Nuclear Reactors Coupled to Closed-Loop Brayton Cycle Systems using SIMULINK™

    NASA Astrophysics Data System (ADS)

    Wright, Steven A.; Sanchez, Travis

    2005-02-01

    The operation of space reactors for both in-space and planetary operations will require unprecedented levels of autonomy and control. Development of these autonomous control systems will require dynamic system models, effective control methodologies, and autonomous control logic. This paper briefly describes the results of reactor, power-conversion, and control models that are implemented in SIMULINK™ (Simulink, 2004). SIMULINK™ is a development environment packaged with MatLab™ (MatLab, 2004) that allows the creation of dynamic state flow models. Simulation modules for liquid metal, gas cooled reactors, and electrically heated systems have been developed, as have modules for dynamic power-conversion components such as, ducting, heat exchangers, turbines, compressors, permanent magnet alternators, and load resistors. Various control modules for the reactor and the power-conversion shaft speed have also been developed and simulated. The modules are compiled into libraries and can be easily connected in different ways to explore the operational space of a number of potential reactor, power-conversion system configurations, and control approaches. The modularity and variability of these SIMULINK™ models provides a way to simulate a variety of complete power generation systems. To date, both Liquid Metal Reactors (LMR), Gas Cooled Reactors (GCR), and electric heaters that are coupled to gas-dynamics systems and thermoelectric systems have been simulated and are used to understand the behavior of these systems. Current efforts are focused on improving the fidelity of the existing SIMULINK™ modules, extending them to include isotopic heaters, heat pipes, Stirling engines, and on developing state flow logic to provide intelligent autonomy. The simulation code is called RPC-SIM (Reactor Power and Control-Simulator).

  19. Dynamic simulation and load-following control of an integrated gasification combined cycle (IGCC) power plant with CO{sub 2} capture

    SciTech Connect

    Bhattacharyya, D,; Turton, R.; Zitney, S.

    2012-01-01

    Load-following control of future integrated gasification combined cycle (IGCC) plants with pre-combustion CO{sub 2} capture is expected to be far more challenging as electricity produced by renewable energy is connected to the grid and strict environmental limits become mandatory requirements. To study control performance during load following, a plant-wide dynamic simulation of a coal-fed IGCC plant with CO{sub 2} capture has been developed. The slurry-fed gasifier is a single-stage, downward-fired, oxygen-blown, entrained-flow type with a radiant syngas cooler (RSC). The syngas from the outlet of the RSC goes to a scrubber followed by a two-stage sour shift process with inter-stage cooling. The acid gas removal (AGR) process is a dual-stage physical solvent-based process for selective removal of H{sub 2}S in the first stage and CO{sub 2} in the second stage. Sulfur is recovered using a Claus unit with tail gas recycle to the AGR. The recovered CO{sub 2} is compressed by a split-shaft multistage compressor and sent for sequestration after being treated in an absorber with triethylene glycol for dehydration. The clean syngas is sent to two advanced “F”-class gas turbines (GTs) partially integrated with an elevated-pressure air separation unit. A subcritical steam cycle is used for heat recovery steam generation. A treatment unit for the sour water strips off the acid gases for utilization in the Claus unit. The steady-state model developed in Aspen Plus® is converted to an Aspen Plus Dynamics® simulation and integrated with MATLAB® for control studies. The results from the plant-wide dynamic model are compared qualitatively with the data from a commercial plant having different configuration, operating condition, and feed quality than what has been considered in this work. For load-following control, the GT-lead with gasifier-follow control strategy is considered. A modified proportional–integral–derivative (PID) control is considered for the syngas

  20. FES cycling.

    PubMed

    Newham, D J; Donaldson, N de N

    2007-01-01

    Spinal cord injury (SCI) leads to a partial or complete disruption of motor, sensory, and autonomic nerve pathways below the level of the lesion. In paraplegic patients, functional electrical stimulation (FES) was originally widely considered as a means to restore walking function but this was proved technically very difficult because of the numerous degrees of freedom involved in walking. FES cycling was developed for people with SCI and has the advantages that cycling can be maintained for reasonably long periods in trained muscles and the risk of falls is low. In the article, we review research findings relevant to the successful application of FES cycling including the effects on muscle size, strength and function, and the cardiovascular and bone changes. We also describe important practical considerations in FES cycling regarding the application of surface electrodes, training and setting up the stimulator limitations, implanted stimulators and FES cycling including FES cycling in groups and other FES exercises such as FES rowing.

  1. CDC-25.1 controls the rate of germline mitotic cell cycle by counteracting WEE-1.3 and by positively regulating CDK-1 in Caenorhabditis elegans.

    PubMed

    Yoon, Sunghee; Kawasaki, Ichiro; Shim, Yhong-Hee

    2012-04-01

    In Caenorhabditis elegans, cdc-25.1 loss-of-function mutants display a lack of germline proliferation. We found that the proliferation defect of cdc-25.1 mutants was suppressed by wee-1.3 RNAi. Further, among the seven cdk and seven cyclin homologs examined, cdk-1 and cyb-3 RNAi treatment caused the most severe germline proliferation defects in an rrf-1 mutant background, which were similar to those of the cdc-25.1 mutants. In addition, while RNAi of cyd-1 and cye-1 caused significant germline proliferation defects, RNAi of cdk-2 and cdk-4 did not. Compared with the number of germ nuclei in wee-1.3(RNAi) worms, the number in wee-1.3(RNAi);cdk-1(RNAi) and wee-1.3(RNAi);cyb-3(RNAi) worms further decreased to the level of cdk-1(RNAi) and cyb-3(RNAi) worms, respectively, indicating that cdk-1 and cyb-3 are epistatic and function downstream of cdc-25.1 and wee-1.3 in the control of the cell cycle. BrdU labeling of adult worms showed that, while 100% of the wild-type germ nuclei in the mitotic region incorporated BrdU when labeled for more than 12 h at 20°C, a small fraction of the cdc-25.1 mutant germ nuclei failed to incorporate BrdU even when labeled for 68 h. These results indicate that CDC-25.1 is required for maintaining proper rate of germline mitotic cell cycle. We propose that CDC-25.1 regulates the rate of germline mitotic cell cycle by counteracting WEE-1.3 and by positively controlling CDK-1, which forms a complex primarily with CYB-3, but also possibly with CYD-1 and CYE-1.

  2. Passive load follow analysis of the STAR-LM and STAR-H2 systems

    NASA Astrophysics Data System (ADS)

    Moisseytsev, Anton

    A steady-state model for the calculation of temperature and pressure distributions, and heat and work balance for the STAR-LM and the STAR-H2 systems was developed. The STAR-LM system is designed for electricity production and consists of the lead cooled reactor on natural circulation and the supercritical carbon dioxide Brayton cycle. The STAR-H2 system uses the same reactor which is coupled to the hydrogen production plant, the Brayton cycle, and the water desalination plant. The Brayton cycle produces electricity for the on-site needs. Realistic modules for each system component were developed. The model also performs design calculations for the turbine and compressors for the CO2 Brayton cycle. The model was used to optimize the performance of the entire system as well as every system component. The size of each component was calculated. For the 400 MWt reactor power the STAR-LM produces 174.4 MWe (44% efficiency) and the STAR-H2 system produces 7450 kg H2/hr. The steady state model was used to conduct quasi-static passive load follow analysis. The control strategy was developed for each system; no control action on the reactor is required. As a main safety criterion, the peak cladding temperature is used. It was demonstrated that this temperature remains below the safety limit during both normal operation and load follow.

  3. Unfolding and translocation pathway of substrate protein controlled by structure in repetitive allosteric cycles of the ClpY ATPase.

    PubMed

    Kravats, Andrea; Jayasinghe, Manori; Stan, George

    2011-02-01

    Clp ATPases are ring-shaped AAA+ motors in the degradation pathway that perform critical actions of unfolding and translocating substrate proteins (SPs) through narrow pores to deliver them to peptidase components. These actions are effected by conserved diaphragm-forming loops found in the central channel of the Clp ATPase hexamer. Conformational changes, that take place in the course of repetitive ATP-driven cycles, result in mechanical forces applied by the central channel loops onto the SP. We use coarse-grained simulations to elucidate allostery-driven mechanisms of unfolding and translocation of a tagged four-helix bundle protein by the ClpY ATPase. Unfolding is initiated at the tagged C-terminal region via an obligatory intermediate. The resulting nonnative conformation is competent for translocation, which proceeds on a different time scale than unfolding and involves sharp stepped transitions. Completion of the translocation process requires assistance from the ClpQ peptidase. These mechanisms contrast nonallosteric mechanical unfolding of the SP. In atomic force microscopy experiments, multiple unfolding pathways are available and large mechanical forces are required to unravel the SP relative to those exerted by the central channel loops of ClpY. SP threading through a nonallosteric ClpY nanopore involves simultaneous unfolding and translocation effected by strong pulling forces.

  4. Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

    SciTech Connect

    Dubiel, R.F. )

    1989-09-01

    Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

  5. Cell Cycle Control and Adhesion Molecule Expression in Cells of the Immune System are Sensitive to Altered Gravity

    NASA Astrophysics Data System (ADS)

    Ullrich, O.; Paulsen, K.; Thiel, C.; Herrmann, K.; Sang, C.; Han, G.; Hemmersbach, R.; von der Wiesche, M.; Kroll, H.; Zhuang, F.; Grote, K. H.; Cogoli, A.; Zipp, F.; Engelmann, F.

    2008-06-01

    Life on earth developed in the presence and under the constant influence of gravity. Thus, it is a fundamental biological question, whether gravity is required for cellular functions and signal transduction in mammalian cells. Since the first Spacelab-Mission 20 years ago, it is known that activation and function of T lymphocytes is severely suppressed in microgravity, but the underlying molecular mechanisms are not elucidated. Experiments have been performed using ground-based facilities such as fast-rotating clinostat and hyper-g-centrifuges, and real microgravity provided by parabolic flights. We found that 1.) cells of the immune system responded cell type specifically to altered gravity, 2.) microgravity induced a multitude of initial alterations in signal transduction, whereas 3.) hypergravity of 1.8g did not induce any changes of the pathways tested, and that 4.) most of the initially altered pathways in microgravity adapted to "normal" levels within 15min. However, some pathways remained altered and could explain cell cycle arrest of T lymphocytes as observed in several long-term space experiments.

  6. Microstructural Features Controlling the Variability in Low-Cycle Fatigue Properties of Alloy Inconel 718DA at Intermediate Temperature

    NASA Astrophysics Data System (ADS)

    Texier, Damien; Gómez, Ana Casanova; Pierret, Stéphane; Franchet, Jean-Michel; Pollock, Tresa M.; Villechaise, Patrick; Cormier, Jonathan

    2016-03-01

    The low-cycle fatigue behavior of two direct-aged versions of the nickel-based superalloy Inconel 718 (IN718DA) was examined in the low-strain amplitude regime at intermediate temperature. High variability in fatigue life was observed, and abnormally short lifetimes were systematically observed to be due to crack initiation at (sub)-surface non-metallic inclusions. However, crack initiation within (sub)-surface non-metallic inclusions did not necessarily lead to short fatigue life. The macro- to micro-mechanical mechanisms of deformation and damage have been examined by means of detailed microstructural characterization, tensile and fatigue mechanical tests, and in situ tensile testing. The initial stages of crack micro-propagation from cracked non-metallic particles into the surrounding metallic matrix occupies a large fraction of the fatigue life and requires extensive local plastic straining in the matrix adjacent to the cracked inclusions. Differences in microstructure that influence local plastic straining, i.e., the δ-phase content and the grain size, coupled with the presence of non-metallic inclusions at the high end of the size distribution contribute strongly to the fatigue life variability.

  7. Notch stimulates growth by direct regulation of genes involved in the control of glycolysis and the tricarboxylic acid cycle

    PubMed Central

    Slaninova, Vera; Krafcikova, Michaela; Perez-Gomez, Raquel; Steffal, Pavel; Trantirek, Lukas; Bray, Sarah J.

    2016-01-01

    Glycolytic shift is a characteristic feature of rapidly proliferating cells, such as cells during development and during immune response or cancer cells, as well as of stem cells. It results in increased glycolysis uncoupled from mitochondrial respiration, also known as the Warburg effect. Notch signalling is active in contexts where cells undergo glycolytic shift. We decided to test whether metabolic genes are direct transcriptional targets of Notch signalling and whether upregulation of metabolic genes can help Notch to induce tissue growth under physiological conditions and in conditions of Notch-induced hyperplasia. We show that genes mediating cellular metabolic changes towards the Warburg effect are direct transcriptional targets of Notch signalling. They include genes encoding proteins involved in glucose uptake, glycolysis, lactate to pyruvate conversion and repression of the tricarboxylic acid cycle. The direct transcriptional upregulation of metabolic genes is PI3K/Akt independent and occurs not only in cells with overactivated Notch but also in cells with endogenous levels of Notch signalling and in vivo. Even a short pulse of Notch activity is able to elicit long-lasting metabolic changes resembling the Warburg effect. Loss of Notch signalling in Drosophila wing discs as well as in human microvascular cells leads to downregulation of glycolytic genes. Notch-driven tissue overgrowth can be rescued by downregulation of genes for glucose metabolism. Notch activity is able to support growth of wing during nutrient-deprivation conditions, independent of the growth of the rest of the body. Notch is active in situations that involve metabolic reprogramming, and the direct regulation of metabolic genes may be a common mechanism that helps Notch to exert its effects in target tissues. PMID:26887408

  8. Temporal Shifts in Radiocarbon in Spring Waters: Implications for Decadal Controls on Element Cycling in a Mountain Catchment

    NASA Astrophysics Data System (ADS)

    Blumhagen, E. D.; Clark, J. F.; Chadwick, O. A.; Derry, L. A.

    2004-12-01

    Groundwater is a good archive of chemical signals inherited from soil processes. How good it is depends on the residence time of water in aquifers, the amount of mixing of radically different flowpaths, and how well the chemical signals are preserved. Here, we present data collected from nine springs in Sagehen basin, northern Sierra Nevada, California with a focus on the variable influence the soil zone has in regulating the chemistry of recharging waters before they eventually enter the groundwater system. CFC and tritium/3He age-dating methods were used to determine the apparent geochemical ages (or mean residence times) of groundwater emerging from these springs. The apparent ages range between 15 and 43 years and correlate positively with concentrations of rock-derived cations (Ca2+, Na+), conductivity, temperature, and pH, demonstrating the geochemical evolution of a shallow groundwater system. In contrast with the major cations, delta C-13 shows little change with age (values range between -17 and -19 permil), indicating that the carbon chemistry is not evolving. Thus, carbon isotopes record soil processes in this groundwater system. Radiocarbon contents range between 87 and 110 pmC and correlate very well with age, whereby the youngest groundwater has the highest radiocarbon values. This temporal variation reflects the movement of radiocarbon, derived from atmospheric nuclear bomb tests, through the biota and soil zone. Unlike the decadal response time of the atmospheric carbon reservoir, attenuation and lag of the radiocarbon spike recorded in our groundwater data suggest that the turnover time of carbon in the soil zone is relatively long, perhaps 100s to 1000s of years. Additionally, we are investigating other tracers (Ge/Si ratios and silicon isotopes) to elucidate dynamics of element cycling and fractionation in the soil zone, that are in turn recorded in the groundwater chemistry.

  9. Cell cycle gene-specific control of transcription has a critical role in proliferation of primordial germ cells

    PubMed Central

    Okamura, Daiji; Maeda, Ikuma; Taniguchi, Hirofumi; Tokitake, Yuko; Ikeda, Makiko; Ozato, Keiko; Mise, Nathan; Abe, Kuniya; Noce, Toshiaki; Izpisua Belmonte, Juan Carlos; Matsui, Yasuhisa

    2012-01-01

    Transcription elongation is stimulated by positive transcription elongation factor b (P-TEFb), for which activity is repressed in the 7SK small nuclear ribonucleoprotein (7SK snRNP) complex. We show here a critical role of 7SK snRNP in growth control of primordial germ cells (PGCs). The expression of p15INK4b, a cyclin-dependent kinase inhibitor (CDKI) gene, in PGCs is selectively activated by P-TEFb and its recruiting molecule, Brd4, when the amount of active P-TEFb is increased due to reduction of the 7SK snRNP, and PGCs consequently undergo growth arrest. These results indicate that CDKI gene-specific control of transcription by 7SK snRNP plays a pivotal role in the maintenance of PGC proliferation. PMID:23154982

  10. Optimal Micro-Scale Secondary Flow Control for the Management of High Cycle Fatigue and Distortion in Compact Inlet Diffusers

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.; Keller, Dennis J.

    2002-01-01

    The purpose of this study on micro-scale secondary flow control (MSFC) is to study the aerodynamic behavior of micro-vane effectors through their factor (i.e., the design variable) interactions and to demonstrate how these statistical interactions, when brought together in an optimal manner, determine design robustness. The term micro-scale indicates the vane effectors are small in comparison to the local boundary layer height. Robustness in this situation means that it is possible to design fixed MSFC robust installation (i.e.. open loop) which operates well over the range of mission variables and is only marginally different from adaptive (i.e., closed loop) installation design, which would require a control system. The inherent robustness of MSFC micro-vane effector installation designs comes about because of their natural aerodynamic characteristics and the manner in which these characteristics are brought together in an optimal manner through a structured Response Surface Methodology design process.

  11. A Prospective Randomized Controlled Study of Laser-Assisted Hatching on the Outcome of First Fresh IVF-ET Cycle in Advanced Age Women.

    PubMed

    Shi, Wenhao; Hongwei, Tan; Zhang, Wei; Li, Na; Li, Mingzhao; Li, Wei; Shi, Juanzi

    2016-10-01

    There is no sufficient data to conclude the benefit of assisted hatching (AH) for advanced age patients. However, AH is routinely performed for advanced age patients undergoing in vitro fertilization (IVF) in China based on some retrospective evidence. It is important to assess the benefit of AH procedure for advanced age patients, especially by analyzing the data from China. This is a prospective randomized controlled trial to evaluate the effect of laser AH in the advanced age patients undergoing IVF. A total of 256 patients conformed to the inclusion criteria, and 78 were excluded by exclusion criteria. A total of 178 patients were eligible and randomized to 2 groups (82 AH group and 96 control group). Laser AH (zona thinning) was performed in the AH group. There were no statistical significance in basic clinical parameters between the 2 groups. No difference was found in implantation rate (AH vs control, 32.45% vs 39.29%) and clinical pregnancy rate (AH vs control, 48.78% vs 59.38%). Our data did not find any benefit of laser AH in improving implantation or pregnancy rates in advanced age women. Due to the potential risk and increasing financial burden, AH should not be routinely performed in first fresh IVF embryo transfer cycle for advanced age women.

  12. The Chlamydomonas cell cycle.

    PubMed

    Cross, Frederick R; Umen, James G

    2015-05-01

    The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important, early-diverging lineage leading to plants; and as a microbe retaining important features of the last eukaryotic common ancestor (LECA) that has been lost in the highly studied yeast lineages. Its cell biology has been studied for many decades and it has well-developed experimental genetic tools, both classical (Mendelian) and molecular. Unlike land plants, it is a haploid with very few gene duplicates, making it ideal for loss-of-function genetic studies. The Chlamydomonas cell cycle has a striking temporal and functional separation between cell growth and rapid cell division, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth and the cell division cycle; it also exhibits a highly choreographed interaction between the cell cycle and its centriole-basal body-flagellar cycle. Here, we review the current status of studies of the Chlamydomonas cell cycle. We begin with an overview of cell-cycle control in the well-studied yeast and animal systems, which has yielded a canonical, well-supported model. We discuss briefly what is known about similarities and differences in plant cell-cycle control, compared with this model. We next review the cytology and cell biology of the multiple-fission cell cycle of Chlamydomonas. Lastly, we review recent genetic approaches and insights into Chlamydomonas cell-cycle regulation that have been enabled by a new generation of genomics-based tools.

  13. Cycle Analysis

    SciTech Connect

    Wright, Steven A.

    2012-03-20

    1. The Cycle Analysis code is an Microsoft Excel code that performs many different types of thermodynamic cycle analysis for power producing systems. The code will calculate the temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component. The code also calculates the power that is produced, the efficiency, and the heat transported in the heater, gas chiller and recuperators. The code provides a schematic of the loop and provides the temperature and pressure at each location in the loop. The code also provides a T-S (temperature-entropy) diagram of the loop and often it provides an pressure enthalpy plot as well. 2. This version of the code concentrates on supercritical CO2 power cycles, but by simply changing the name of the working fluid many other types of fluids can be analyzed. The Cycle Analysis code provided here contains 18 different types of power cycles. Each cycle is contained in one worksheet or tab that the user can select. The user can change the yellow highlighted regions to perform different thermodynamic cycle analysis.

  14. Cycle Analysis

    2012-03-20

    1. The Cycle Analysis code is an Microsoft Excel code that performs many different types of thermodynamic cycle analysis for power producing systems. The code will calculate the temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component. The code also calculates the power that is produced, the efficiency, and the heat transported in the heater, gas chiller and recuperators. The code provides a schematic of the loop andmore » provides the temperature and pressure at each location in the loop. The code also provides a T-S (temperature-entropy) diagram of the loop and often it provides an pressure enthalpy plot as well. 2. This version of the code concentrates on supercritical CO2 power cycles, but by simply changing the name of the working fluid many other types of fluids can be analyzed. The Cycle Analysis code provided here contains 18 different types of power cycles. Each cycle is contained in one worksheet or tab that the user can select. The user can change the yellow highlighted regions to perform different thermodynamic cycle analysis.« less

  15. Association between intrafollicular concentration of benzene and outcome of controlled ovarian stimulation in IVF/ICSI cycles: a pilot study

    PubMed Central

    2014-01-01

    Background Several studies have shown that exposure to benzene is associated to menstrual disorders, miscarriages and other disorders of the reproductive system. We performed an observational prospective pilot study to evaluate if levels of benzene in follicular fluid were correlated with response to controlled ovarian stimulation. Method Thirty-four normogonadotrophic women undergoing IVF were enrolled. Intra-follicular benzene levels were evaluated by chromatography/mass spectrometry. Based on median benzene level, we divided the study population in two groups: Group A with a “low” intra-follicular benzene concentration (n = 19, benzene <0.54 ng/mL) and Group B with a “high” intra-follicular benzene concentration (n = 15, benzene ≥ 0.54 ng/mL). The ovarian response to gonadotrophins and the outcome of IVF were analyzed in the two groups. Results The two groups did not differ in terms of demographic or anthropometric characteristics. Group B had significantly higher basal FSH levels, lower estradiol peak concentration, and fewer oocytes retrieved and embryos transferred (p < 0.05). Number of gonadotrophin vials, length of controlled ovarian stimulation and ongoing pregnancy rate were similar in the two groups. Conclusion In conclusion, ovarian response to endogenous and exogenous gonadotrophins appeared to be influenced by intra-follicular benzene levels. PMID:24991235

  16. Is the torpor-arousal cycle of hibernation controlled by a non-temperature-compensated circadian clock?

    PubMed

    Malan, André

    2010-06-01

    During the hibernation season, mammalian hibernators alternate between prolonged bouts of torpor with a reduced body temperature (Tb) and short arousals with a return to euthermy. Evidence is presented here to show that this metabolic-and also physiological and neuroanatomical-rhythm is controlled by a clock, the torpor-arousal (TA) clock. The temperature dependence of torpor bout duration in 3 species of Spermophilus (published data) may be described by assuming that the TA clock is a circadian clock (probably not the suprachiasmatic clock) that has lost its temperature compensation. This loss might result either from a permanent deletion, or more likely from a seasonal epigenetic control at the level of the clock gene machinery. This hypothesis was verified over the full Tb range on published data from 5 other species (a monotreme, a marsupial, and 3 placental mammals). In a hibernation season, instantaneous subjective time of the putative TA clock was summated over each torpor bout. For each animal, torpor bout length (TBL) was accurately predicted as a constant fraction of a subjective day, for actual durations in astronomical time varying between 4 and 13 to 20 days. The resulting temperature dependence of the interval between arousals predicts that energy expenditure over the hibernation season will be minimal when Tb is as low as possible without eliciting cold thermogenesis. PMID:20484688

  17. The ceramide-activated protein phosphatase Sit4p controls lifespan, mitochondrial function and cell cycle progression by regulating hexokinase 2 phosphorylation.

    PubMed

    Barbosa, António Daniel; Pereira, Clara; Osório, Hugo; Moradas-Ferreira, Pedro; Costa, Vítor

    2016-06-17

    Sit4p is the catalytic subunit of a ceramide-activated PP2A-like phosphatase that regulates cell cycle, mitochondrial function, oxidative stress resistance and chronological lifespan in yeast. In this study, we show that hexokinase 2 (Hxk2p) is hyperphosphorylated in sit4Δ mutants grown in glucose medium by a Snf1p-independent mechanism and Hxk2p-S15A mutation suppresses phenotypes associated with SIT4 deletion, namely growth arrest at G1 phase, derepression of mitochondrial respiration, H2O2 resistance and lifespan extension. Consistently, the activation of Sit4p in isc1Δ mutants, which has been associated with premature aging, leads to Hxk2p hypophosphorylation, and the expression of Hxk2p-S15E increases the lifespan of isc1Δ cells. The overall results suggest that Hxk2p functions downstream of Sit4p in the control of cell cycle, mitochondrial function, oxidative stress resistance and chronological lifespan.

  18. Cell-cycle-regulated control of VSG expression site silencing by histones and histone chaperones ASF1A and CAF-1b in Trypanosoma brucei.

    PubMed

    Alsford, Sam; Horn, David

    2012-11-01

    Antigenic variation in African trypanosomes involves monoallelic expression and reversible silencing of variant surface glycoprotein (VSG) genes found adjacent to telomeres in polycistronic expression sites (ESs). We assessed the impact on ES silencing of five candidate essential chromatin-associated factors that emerged from a genome-wide RNA interference viability screen. Using this approach, we demonstrate roles in VSG ES silencing for two histone chaperones. Defects in S-phase progression in cells depleted for histone H3, or either chaperone, highlight in particular the link between chromatin assembly and DNA replication control. S-phase checkpoint arrest was incomplete, however, allowing G2/M-specific VSG ES derepression following knockdown of histone H3. In striking contrast, knockdown of anti-silencing factor 1A (ASF1A) allowed for derepression at all cell cycle stages, whereas knockdown of chromatin assembly factor 1b (CAF-1b) revealed derepression predominantly in S-phase and G2/M. Our results support a central role for chromatin in maintaining VSG ES silencing. ASF1A and CAF-1b appear to play constitutive and DNA replication-dependent roles, respectively, in the recycling and assembly of chromatin. Defects in these functions typically lead to arrest in S-phase but defective cells can also progress through the cell cycle leading to nucleosome depletion and derepression of telomeric VSG ESs.

  19. dFMRP and Caprin, translational regulators of synaptic plasticity, control the cell cycle at the Drosophila mid-blastula transition

    PubMed Central

    Papoulas, Ophelia; Monzo, Kathryn F.; Cantin, Greg T.; Ruse, Cristian; Yates, John R.; Ryu, Young Hee; Sisson, John C.

    2010-01-01

    The molecular mechanisms driving the conserved metazoan developmental shift referred to as the mid-blastula transition (MBT) remain mysterious. Typically, cleavage divisions give way to longer asynchronous cell cycles with the acquisition of a gap phase. In Drosophila, rapid synchronous nuclear divisions must pause at the MBT to allow the formation of a cellular blastoderm through a special form of cytokinesis termed cellularization. Drosophila Fragile X mental retardation protein (dFMRP; FMR1), a transcript-specific translational regulator, is required for cellularization. The role of FMRP has been most extensively studied in the nervous system because the loss of FMRP activity in neurons causes the misexpression of specific mRNAs required for synaptic plasticity, resulting in mental retardation and autism in humans. Here, we show that in the early embryo dFMRP associates specifically with Caprin, another transcript-specific translational regulator implicated in synaptic plasticity, and with eIF4G, a key regulator of translational initiation. dFMRP and Caprin collaborate to control the cell cycle at the MBT by directly mediating the normal repression of maternal Cyclin B mRNA and the activation of zygotic frühstart mRNA. These findings identify two new targets of dFMRP regulation and implicate conserved translational regulatory mechanisms in processes as diverse as learning, memory and early embryonic development. PMID:21068064

  20. Metal and acidity fluxes controlled by precipitation/dissolution cycles of sulfate salts in an anthropogenic mine aquifer

    NASA Astrophysics Data System (ADS)

    Cánovas, C. R.; Macías, F.; Pérez-López, R.

    2016-05-01

    Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40 days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in

  1. Metal and acidity fluxes controlled by precipitation/dissolution cycles of sulfate salts in an anthropogenic mine aquifer.

    PubMed

    Cánovas, C R; Macías, F; Pérez-López, R

    2016-05-01

    Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in

  2. Metal and acidity fluxes controlled by precipitation/dissolution cycles of sulfate salts in an anthropogenic mine aquifer.

    PubMed

    Cánovas, C R; Macías, F; Pérez-López, R

    2016-05-01

    Underground mine drainages are extremely difficult to study due to the lack of information about the flow path and source proximity in relation to the outflow adit. Geochemical processes controlling metals and acidity fluxes in a complex anthropogenic mine aquifer in SW Spain during the dry and rainy season were investigated by geochemical and statistical tools. High concentrations of acidity, sulfate, metals and metalloids (e.g. Fe, Cu, Zn, As, Cd, Ni, Co) were observed due to intense sulfide oxidation processes. The high residence time inside the anthropogenic aquifer, around 40days, caused the release of significant quantities of metals linked to host rocks (e.g. Al, Ca, Ge, Li, Mg, REE). The most outstanding characteristic of the acid mine drainage (AMD) outflows is the existence of higher Fe/SO4 molar ratios than those theoretical of pyrite (0.50) during most of the monitored period, due to a fire which occurred in 1949 and remained active for decades. Permanent and temporal retention mechanisms of acidity and metals were observed in the galleries. Once released from sulfide oxidation, Pb and As are sorbed on Fe oxyhydroxysulfate or precipitated as low solubility minerals (i.e. anglesite) inside the galleries. The precipitation of evaporitic sulfate salts during the dry season and the subsequent re-dissolution after rainfall control the fluxes of acidity and main metals (i.e. Fe, Mg, Al) from this anthropogenic aquifer. Some elements, such as Cd, Cu, Ni, REE and Zn, are retained in highly soluble sulfate salts while other elements, such as Ge, Pb and Sc, have a lower response to washout processes due to its incorporation in less soluble sulfate salts. In this way, metal concentration during the washout processes would be controlled by the proportion and solubility of each type of evaporitic sulfate salt stored during the dry season. The recovery of metals of economic interest contained in the AMD could help to self-finance the remediation of these waters in

  3. Kinetic Modeling of Arsenic Cycling by a Freshwater Cyanobacterium as Influenced by N:P Ratios: A Potential Biologic Control in an Iron-Limited Drainage Basin

    NASA Astrophysics Data System (ADS)

    Markley, C. T.; Herbert, B. E.

    2004-12-01

    Elevated As levels are common in South Texas surface waters, where As is derived from the natural weathering of geogenic sources and a byproduct of historical uranium mining. The impacted surface waters of the Nueces River drainage basin supply Lake Corpus Christi (LCC), a major drinking water reservoir for the Corpus Christi area. The soils and sediments of the Nueces River drainage basin generally have low levels of reactive iron (average concentration of 2780 mg/kg), limiting the control of iron oxyhydroxides on As geochemistry and bioavailability. Given these conditions, biologic cycling of As may have a large influence on As fate and transport in LCC. Sediment cores from LCC show evidence for cyanobacterial blooms after reservoir formation based upon stable isotopes, total organic matter and specific elemental correlations. While algae have been shown to accumulate and reduce inorganic As(V), few studies have reported biologic cycling of As by cyanobacteria. Therefore, As(V) uptake, accumulation, reduction, and excretion in a 1.0 μ M As(V) solution by the freshwater cyanobacterium, Anabaena sp. Strain PCC 7120, was measured over time as a function of low, middle and high N:P ratios (1.2, 12, 120) to determine nutrient effects on As cycling by the cyanobacterium. Total As(V) reduction was observed in all three conditions upon completion of the ten-day experiment. Maximum As(V) reduction rates ranged from (0.013 mmol g C-1 day-1) in the low N:P solution to (0.398 mmol g C-1 day-1) in the high N:P solution. Increased cell biomass in the low N:P ratio solution compensated for the low maximum reduction rate to allow total As(V) reduction. Kinetic equations commonly used to model algal-nutrient interactions were utilized in modeling the current data. The Michaelis-Menten enzyme saturation equation modified with a competitive inhibition term adequately modeled As(III) excretion in the high and middle N:P ratio test conditions. The low N:P test condition further

  4. DRIVE CYCLE EFFICIENCY AND EMISSIONS ESTIMATES FOR REACTIVITY CONTROLLED COMPRESSION IGNITION IN A MULTI-CYLINDER LIGHT-DUTY DIESEL ENGINE

    SciTech Connect

    Curran, Scott; Briggs, Thomas E; Cho, Kukwon; Wagner, Robert M

    2011-01-01

    In-cylinder blending of gasoline and diesel to achieve Reactivity Controlled Compression Ignition (RCCI) has been shown to reduce NOx and PM emissions while maintaining or improving brake thermal efficiency as compared to conventional diesel combustion (CDC). The RCCI concept has an advantage over many advanced combustion strategies in that by varying both the percent of premixed gasoline and EGR rate, stable combustion can be extended over more of the light-duty drive cycle load range. Changing the percent premixed gasoline changes the fuel reactivity stratification in the cylinder providing further control of combustion phasing and pressure rise rate than the use of EGR alone. This paper examines the combustion and emissions performance of light-duty diesel engine using direct injected diesel fuel and port injected gasoline to carry out RCCI for steady-state engine conditions which are consistent with a light-duty drive cycle. A GM 1.9L four-cylinder engine with the stock compression ratio of 17.5:1, common rail diesel injection system, high-pressure EGR system and variable geometry turbocharger was modified to allow for port fuel injection with gasoline. Engine-out emissions, engine performance and combustion behavior for RCCI operation is compared against both CDC and a premixed charge compression ignition (PCCI) strategy which relies on high levels of EGR dilution. The effect of percent of premixed gasoline, EGR rate, boost level, intake mixture temperature, combustion phasing and pressure rise rate is investigated for RCCI combustion for the light-duty modal points. Engine-out emissions of NOx and PM were found to be considerably lower for RCCI operation as compared to CDC and PCCI, while HC and CO emissions were higher. Brake thermal efficiency was similar or higher for many of the modal conditions for RCCI operation. The emissions results are used to estimate hot-start FTP-75 emissions levels with RCCI and are compared against CDC and PCCI modes.

  5. FW2.2 and cell cycle control in developing tomato fruit: a possible example of gene co-option in the evolution of a novel organ.

    PubMed

    Cong, Bin; Tanksley, Steven D

    2006-12-01

    fw2.2 is one of the few QTLs thus far isolated from plants and the first one known to control fruit size. While it has been established that FW2.2 is a regulator (either directly or indirectly) of cell division, FW2.2 does not share sequence homology to any protein of known function (Frary et al. Science 289:85-88, 2000; Cong et al. Proc Natl Acad Sci USA 99:13606-13611, 2002; Liu et al. Plant Physiol 132:292-299, 2003). Thus, the mechanism by which FW2.2 mediates cell division in developing fruit is currently unknown. In an effort to remedy this situation, a combination of yeast two-hybrid screens, in vitro binding assays and cell bombardment studies were performed. The results provide strong evidence that FW2.2 physically interacts at or near the plasma membrane with the regulatory (beta) subunit of a CKII kinase. CKII kinases are well-studied in both yeast and animals where they form part of cell cycle related signaling pathway. Thus while FW2.2 is a plant-specific protein and regulates cell division in a specialized plant organ (fruit), it appears to participate in a cell-cycle control signal transduction pathway that predates the divergence of single- and multi-cellular organisms. These results thus provide a glimpse into how ancient and conserved regulatory processes can be co-opted in the evolution of novel organs such as fruit. PMID:16941207

  6. Osteocyte control of bone remodeling: is sclerostin a key molecular coordinator of the balanced bone resorption-formation cycles?

    PubMed

    Sapir-Koren, R; Livshits, G

    2014-12-01

    Osteocytes, entrapped within a newly mineralized bone matrix, possess a unique cellular identity due to a specialized morphology and a molecular signature. These features endow them to serve as a bone response mechanism for mechanical stress in their microenvironment. Sclerostin, a primarily osteocyte product, is widely considered as a mechanotranduction key molecule whose expression is suppressed by mechanical loading, or it is induced by unloading. This review presents a model suggesting that sclerostin is major mediator for integrating mechanical, local, and hormonal signals, sensed by the osteocytes, in controlling the remodeling apparatus. This central role is achieved through interplay between two opposing mechanisms: (1) unloading-induced high sclerostin levels, which antagonize Wnt-canonical-β-catenin signaling in osteocytes and osteoblasts, permitting simultaneously Wnt-noncanonical and/or other pathways in osteocytes and osteoclasts, directed at bone resorption; (2) mechanical loading results in low sclerostin levels, activation of Wnt-canonical signaling, and bone formation. Therefore, adaptive bone remodeling occurring at a distinct bone compartment is orchestrated by altered sclerostin levels, which regulate the expression of the other osteocyte-specific proteins, such as RANKL, OPG, and proteins encoded by "mineralization-related genes" (DMP1, PHEX, and probably FGF23). For example, under specific terms, sclerostin regulates differential RANKL and OPG production, and creates a dynamic RANKL/OPG ratio, leading either to bone formation or resorption. It also controls the expression of PHEX, DMP1, and most likely FGF23, leading to either bone matrix mineralization or its inhibition. Such opposing up- or down-regulation of remodeling phases allows osteocytes to function as an "external unit", ensuring transition from bone resorption to bone formation.Mini Abstract: The osteocyte network plays a central role in directing bone response either to mechanical

  7. Diverse effects of RacV12 on cell transformation by Raf: partial inhibition of morphological transformation versus deregulation of cell cycle control.

    PubMed

    Kerkhoff, Eugen; Leberfinger, Cornelia B; Schmidt, Gudula; Aktories, Klaus; Rapp, Ulf R

    2002-04-01

    Activated Raf kinases and Rac GTPases were shown to cooperate in the oncogenic transformation of fibroblasts, which is characterised by the disassembly of the cellular actin cytoskeleton, a nearly complete loss of focal adhesion complexes and deregulated cell proliferation. This is surprising since the Rac GTPase induces actin structures and the adhesion of suspended cells to extracellular matrix proteins. NIH 3T3 cells expressing a hydroxytamoxifen-inducible oncogenic c-Raf-1-oestrogen receptor fusion protein (c-Raf-1-BxB-ER, N-BxB-ER cells) undergo morphological transformation upon stimulation of the Raf kinase. We show that treatment with the Rac, Rho and Cdc42 activating Escherichia coli toxin CNF1 or coexpression of an activated RacV12 mutant partially inhibits and reverses the disassembly of cellular actin structures and focal adhesion complexes by oncogenic Raf. Activation of the Rac GTPase restores actin structures and focal adhesion complexes at the cellular boundary, leading to spreading of the otherwise spindle-shaped Raf-transformed cells. Actin stress fibres, however, which are regulated by the function of the Rho GTPase, are disassembled by oncogenic Raf even in the presence of activated Rac and Rho. With respect to the RacV12-mediated spreading of Raf-transformed cells, we postulate an anti-oncogenic function of the activated Rac. Another feature of cell transformation is the deregulation of cell cycle control. NIH 3T3 cells expressing high levels of the c-Raf-1-BxB-ER protein undergo a cell cycle arrest upon stimulation of the oncogenic Raf kinase. Our results show that in N-BxB-ER-RacV12 cells the expression of the activated RacV12 mediates cell proliferation in the presence of high-intensity Raf signals and high levels of the Cdk inhibitor p21(Cip1). These results indicate a pro-oncogenic function of the Rac GTPase with respect to the deregulation of cell cycle control.

  8. Large fluctuations in the effective population size of the malaria mosquito Anopheles gambiae s.s. during vector control cycle.

    PubMed

    Hodges, Theresa K; Athrey, Giridhar; Deitz, Kevin C; Overgaard, Hans J; Matias, Abrahan; Caccone, Adalgisa; Slotman, Michel A

    2013-12-01

    On Bioko Island, Equatorial Guinea, indoor residual spraying (IRS) has been part of the Bioko Island Malaria Control Project since early 2004. Despite success in reducing childhood infections, areas of high transmission remain on the island. We therefore examined fluctuations in the effective population size (N e ) of the malaria vector Anopheles gambiae in an area of persistent high transmission over two spray rounds. We analyzed data for 13 microsatellite loci from 791 An. gambiae specimens collected at six time points in 2009 and 2010 and reconstructed the demographic history of the population during this period using approximate Bayesian computation (ABC). Our analysis shows that IRS rounds have a large impact on N e , reducing it by 65%-92% from prespray round N e . More importantly, our analysis shows that after 3-5 months, the An. gambiae population rebounded by 2818% compared shortly following the spray round. Our study underscores the importance of adequate spray round frequency to provide continuous suppression of mosquito populations and that increased spray round frequency should substantially improve the efficacy of IRS campaigns. It also demonstrates the ability of ABC to reconstruct a detailed demographic history across only a few tens of generations in a large population.

  9. Plastid RNA polymerases: orchestration of enzymes with different evolutionary origins controls chloroplast biogenesis during the plant life cycle.

    PubMed

    Pfannschmidt, Thomas; Blanvillain, Robert; Merendino, Livia; Courtois, Florence; Chevalier, Fabien; Liebers, Monique; Grübler, Björn; Hommel, Elisabeth; Lerbs-Mache, Silva

    2015-12-01

    Chloroplasts are the sunlight-collecting organelles of photosynthetic eukaryotes that energetically drive the biosphere of our planet. They are the base for all major food webs by providing essential photosynthates to all heterotrophic organisms including humans. Recent research has focused largely on an understanding of the function of these organelles, but knowledge about the biogenesis of chloroplasts is rather limited. It is known that chloroplasts develop from undifferentiated precursor plastids, the proplastids, in meristematic cells. This review focuses on the activation and action of plastid RNA polymerases, which play a key role in the development of new chloroplasts from proplastids. Evolutionarily, plastids emerged from the endosymbiosis of a cyanobacterium-like ancestor into a heterotrophic eukaryote. As an evolutionary remnant of this process, they possess their own genome, which is expressed by two types of plastid RNA polymerase, phage-type and prokaryotic-type RNA polymerase. The protein subunits of these polymerases are encoded in both the nuclear and plastid genomes. Their activation and action therefore require a highly sophisticated regulation that controls and coordinates the expression of the components encoded in the plastid and nucleus. Stoichiometric expression and correct assembly of RNA polymerase complexes is achieved by a combination of developmental and environmentally induced programmes. This review highlights the current knowledge about the functional coordination between the different types of plastid RNA polymerases and provides working models of their sequential expression and function for future investigations. PMID:26355147

  10. Large fluctuations in the effective population size of the malaria mosquito Anopheles gambiae s.s. during vector control cycle

    PubMed Central

    Hodges, Theresa K; Athrey, Giridhar; Deitz, Kevin C; Overgaard, Hans J; Matias, Abrahan; Caccone, Adalgisa; Slotman, Michel A

    2013-01-01

    On Bioko Island, Equatorial Guinea, indoor residual spraying (IRS) has been part of the Bioko Island Malaria Control Project since early 2004. Despite success in reducing childhood infections, areas of high transmission remain on the island. We therefore examined fluctuations in the effective population size (Ne) of the malaria vector Anopheles gambiae in an area of persistent high transmission over two spray rounds. We analyzed data for 13 microsatellite loci from 791 An. gambiae specimens collected at six time points in 2009 and 2010 and reconstructed the demographic history of the population during this period using approximate Bayesian computation (ABC). Our analysis shows that IRS rounds have a large impact on Ne, reducing it by 65%–92% from prespray round Ne. More importantly, our analysis shows that after 3–5 months, the An. gambiae population rebounded by 2818% compared shortly following the spray round. Our study underscores the importance of adequate spray round frequency to provide continuous suppression of mosquito populations and that increased spray round frequency should substantially improve the efficacy of IRS campaigns. It also demonstrates the ability of ABC to reconstruct a detailed demographic history across only a few tens of generations in a large population. PMID:24478799

  11. Microbially-mediated thiocyanate oxidation and manganese cycling control arsenic mobility in groundwater at an Australian gold mine

    NASA Astrophysics Data System (ADS)

    Horvath, A. S.; Baldisimo, J. G.; Moreau, J. W.

    2010-12-01

    Arsenic contamination of groundwater poses a serious environmental and human health problem in many regions around the world. Historical groundwater chemistry data for a Western-Central Victorian gold mine (Australia) revealed a strong inverse correlation between dissolved thiocyanate and iron(II), supporting the interpretation that oxidation of thiocyanate, a major groundwater contaminant by-product of cyanide-based gold leaching, was coupled to reductive dissolution of iron ox(yhydrox)ides in tailings dam sediments. Microbial growth was observed in this study in a selective medium using SCN- as the sole carbon and nitrogen source. The potential for use of SCN- as a tracer of mining contamination in groundwater was evaluated in the context of biological SCN- oxidation potential in the aquifer. Geochemical data also revealed a high positive correlation between dissolved arsenic and manganese, indicating that sorption on manganese-oxides most likely controls arsenic mobility at this site. Samples of groundwater and sediments along a roughly straight SW-NE traverse away from a large mine tailings storage facility, and parallel to the major groundwater flow direction, were analysed for major ions and trace metals. Groundwater from wells approaching the tailings along this traverse showed a nearly five-fold increase (roughly 25-125 ppb) in dissolved arsenic concentrations relative to aqueous Mn(II) concentrations. Thus, equivalent amounts of dissolved manganese released a five-fold difference in the amount of adsorbed arsenic. The interpretation that reductive dissolution of As-bearing MnO2 at the mine site has been mediated by groundwater (or aquifer) microorganisms is consistent with our recovery of synthetic birnessite-reducing enrichment cultures that were inoculated with As-contaminated groundwaters.

  12. Landform controls on low level moisture convergence and the diurnal cycle of warm season orographic rainfall in the Southern Appalachians

    NASA Astrophysics Data System (ADS)

    Wilson, Anna M.; Barros, Ana P.

    2015-12-01

    The Advanced Weather Research and Forecasting (WRF) model was used to simulate two warm season events representative of reverse orographic enhancement of warm season precipitation in the Southern Appalachians under weak (9-12 July, 2012) and strong (12-16 May, 2014) synoptic forcing conditions. Reverse orographic enhancement refers to significant enhancement of rainfall intensity (up to one order of magnitude) at low elevations in the inner mountain valleys, but not in the ridges. This is manifest in significant increases of radar reflectivity observations and associated integral quantities (rain rate) at low levels (within 500 m of the surface), as well as changes in the observed microphysical properties of rainfall (raindrop size distribution). Analysis of high-resolution (1.25 km × 1.25 km) WRF simulations shows that the model captures the march of observed rainfall, though not the timing in the case of strong synoptic forcing. For each event, the results show that the space-time variability of rainfall in the inner region is strongly coupled to the development and persistence of organized within-valley low-level moisture convergence that is a necessary precursor to valley fog and low level cloud formation. Microphysical interactions among precipitation from propagating storm systems, and local low-level clouds and fog promote coalescence efficiency through the seeder-feeder mechanism leading to significant enhancement of rainfall intensity near the ground as shown by Wilson and Barros (2014). The simulations support the hypothesis that ridge-valley precipitation gradients, and in particular the reverse orographic enhancement effects in inner mountain valleys, are linked to horizontal heterogeneity in the vertical structure of low level clouds and precipitation promoted through landform controls on moisture convergence.

  13. Vapor Compression Cycle Design Program (CYCLE_D)

    National Institute of Standards and Technology Data Gateway

    SRD 49 NIST Vapor Compression Cycle Design Program (CYCLE_D) (PC database for purchase)   The CYCLE_D database package simulates the vapor compression refrigeration cycles. It is fully compatible with REFPROP 9.0 and covers the 62 single-compound refrigerants . Fluids can be used in mixtures comprising up to five components.

  14. Coupling the Mars Dust and Water Cycles: Investigating the Role of Clouds in Controlling the Vertical Distribution of Dust During N. H. Summer

    NASA Technical Reports Server (NTRS)

    Kahre, M. A.; Haberle, R. M.; Hollingsworth, J. L.; Wilson, R. J.

    2014-01-01

    The dust cycle is critically important for the current climate of Mars. The radiative effects of dust impact the thermal and dynamical state of the atmosphere (Gierasch and Goody, 1968; Haberle et al., 1982; Zurek et al., 1992). Although dust is present in the Martian atmosphere throughout the year, the level of dustiness varies with season. The atmosphere is generally the dustiest during northern fall and winter and the least dusty during northern spring and summer (Smith, 2004). Dust particles are lifted into the atmosphere by dust storms that range in size from meters to thousands of kilometers across (Cantor et al., 2001). During some years, regional storms combine to produce hemispheric or planet encircling dust clouds that obscure the surface and raise atmospheric temperatures by as much as 40 K (Smith et al., 2002). Key recent observations of the vertical distribution of dust indicate that elevated layers of dust exist in the tropics and sub-tropics throughout much of the year (Heavens et al., 2011). These observations have brought particular focus on the processes that control the vertical distribution of dust in the Martian atmosphere. The goal of this work is to further our understanding of how clouds in particular control the vertical distribution of dust, particularly during N. H. spring and summer

  15. Limit cycle stability analysis and adaptive control of a multi-compartment model for a pressure-limited respirator and lung mechanics system

    NASA Astrophysics Data System (ADS)

    Chellaboina, VijaySekhar; Haddad, Wassim M.; Li, Hancao; Bailey, James M.

    2010-05-01

    Acute respiratory failure due to infection, trauma or major surgery is one of the most common problems encountered in intensive care units, and mechanical ventilation is the mainstay of supportive therapy for such patients. In this article, we develop a general mathematical model for the dynamic behaviour of a multi-compartment respiratory system in response to an arbitrary applied inspiratory pressure. Specifically, we use compartmental dynamical system theory and Poincaré maps to model and analyse the dynamics of a pressure-limited respirator and lung mechanics system, and show that the periodic orbit generated by this system is globally asymptotically stable. Furthermore, we show that the individual compartmental volumes, and hence the total lung volume, converge to steady-state end-inspiratory and end-expiratory values. Finally, we develop a model reference direct adaptive controller framework for the multi-compartmental model of a pressure-limited respirator and lung mechanics system where the plant and reference model involve switching and time-varying dynamics. We then apply the proposed adaptive feedback controller framework to stabilise a given limit cycle corresponding to a clinically plausible respiratory pattern.

  16. PKM2 uses control of HuR localization to regulate p27 and cell cycle progression in human glioblastoma cells.

    PubMed

    Mukherjee, Joydeep; Ohba, Shigeo; See, Wendy L; Phillips, Joanna J; Molinaro, Annette M; Pieper, Russell O

    2016-07-01

    The M2 isoform of pyruvate kinase (PK) is upregulated in most cancers including glioblastoma. Although PKM2 has been reported to use dual kinase activities to regulate cell growth, it also interacts with phosphotyrosine (pY)-containing peptides independently of its kinase activity. The potential for PKM2 to use the binding of pY-containing proteins to control tumor growth has not been fully examined. We here describe a novel mechanism by which PKM2 interacts in the nucleus with the RNA binding protein HuR to regulate HuR sub-cellular localization, p27 levels, cell cycle progression and glioma cell growth. Suppression of PKM2 in U87, T98G and LN319 glioma cells resulted in increased p27 levels, defects in entry into mitosis, increased centrosome number, and decreased cell growth. These effects could be reversed by shRNA targeting p27. The increased levels of p27 in PKM2 knock-down cells were caused by a loss of the nuclear interaction between PKM2 and HuR, and a subsequent cytoplasmic re-distribution of HuR, which in turn led to increased cap-independent p27 mRNA translation. Consistent with these results, the alterations in p27 mRNA translation, cell cycle progression and cell growth caused by PKM2 suppression could be reversed in vitro and in vivo by suppression of HuR or p27 levels, or by introduction of forms of PKM2 that could bind pY, regardless of their kinase activity. These results define a novel mechanism by which PKM2 regulates glioma cell growth, and also define a novel set of potential therapeutic targets along the PKM2-HuR-p27 pathway. PMID:26874904

  17. PKM2 uses control of HuR localization to regulate p27 and cell cycle progression in human glioblastoma cells.

    PubMed

    Mukherjee, Joydeep; Ohba, Shigeo; See, Wendy L; Phillips, Joanna J; Molinaro, Annette M; Pieper, Russell O

    2016-07-01

    The M2 isoform of pyruvate kinase (PK) is upregulated in most cancers including glioblastoma. Although PKM2 has been reported to use dual kinase activities to regulate cell growth, it also interacts with phosphotyrosine (pY)-containing peptides independently of its kinase activity. The potential for PKM2 to use the binding of pY-containing proteins to control tumor growth has not been fully examined. We here describe a novel mechanism by which PKM2 interacts in the nucleus with the RNA binding protein HuR to regulate HuR sub-cellular localization, p27 levels, cell cycle progression and glioma cell growth. Suppression of PKM2 in U87, T98G and LN319 glioma cells resulted in increased p27 levels, defects in entry into mitosis, increased centrosome number, and decreased cell growth. These effects could be reversed by shRNA targeting p27. The increased levels of p27 in PKM2 knock-down cells were caused by a loss of the nuclear interaction between PKM2 and HuR, and a subsequent cytoplasmic re-distribution of HuR, which in turn led to increased cap-independent p27 mRNA translation. Consistent with these results, the alterations in p27 mRNA translation, cell cycle progression and cell growth caused by PKM2 suppression could be reversed in vitro and in vivo by suppression of HuR or p27 levels, or by introduction of forms of PKM2 that could bind pY, regardless of their kinase activity. These results define a novel mechanism by which PKM2 regulates glioma cell growth, and also define a novel set of potential therapeutic targets along the PKM2-HuR-p27 pathway.

  18. Controls on magmatic cycles and development of rift topography of the Manda Hararo segment (Afar, Ethiopia): Insights from cosmogenic 3He investigation of landscape evolution

    NASA Astrophysics Data System (ADS)

    Medynski, S.; Pik, R.; Burnard, P.; Williams, A.; Vye-Brown, C.; Ferguson, D.; Blard, P.-H.; France, L.; Yirgu, G.; Seid, J. I.; Ayalew, D.; Calvert, A.

    2013-04-01

    Crustal extension at mature continental rifts and oceanic ridges occurs by a combination of normal faulting and magma injection, which interact to create rift morphology. Quantifying the relative roles of faulting and melt intrusion in accommodating extension at magmatic rifts remains difficult and requires studies at sufficient spatial and temporal scales to resolve the interaction between these processes. In this study we provide new chronological constraints based on cosmogenic exposure dating for the ˜100 kyr topographic evolution of a young and active magmatic rift segment in Afar, Ethiopia. We combine structural investigations, field mapping, geochemical analysis and cosmogenic 3He exposure dating of lava surfaces in order to investigate the interplay between volcanic activity and fault growth in the northern part of the axial depression, where the rift segment intersects a large stratovolcano. Our results allow us to determine the roles of the various magma reservoirs feeding this rift system and their interactions during accretion over the past 100 kyr. New age data for key lava units allow several magmatic cycles to be distinguished. Each cycle lasts 20-40 ka resulting in periods of high and low magma supply rate. The variations in magma supply rate at the segment extremity strongly affect the development of the rift depression, with the availability of melt controlling the morphological impact of faulting. Melts from different magma reservoirs feeding the segment are chemically distinct and geochemical analysis of lavas from the rift floor allows their respective contributions to maintaining magmatic accretion to be estimated. We propose that melts from the magma reservoir at the northern end of the segment contribute around one-third of the length of this portion of the segment, whereas the mid-segment reservoir is responsible for the remaining two-thirds of the segment accretion.

  19. A Comparison of Possible Physical, Chemical, and Microbial Functional Gene Controls on Methane Cycling at Two Distinct Sites on the Alaskan North Slope.

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    2014-12-01

    Greater thaw depth in the Arctic permafrost regions will increase soil liquid-water content and enrich for the microbial production of methane (CH4). Carbon cycling in Arctic soils is poorly understood with regard to biological controls on observed CH4 fluxes. In the analysis presented here I have measured and compared chemical and physical properties and conducted an anaerobic incubation experiment on soil core samples obtained from Atqasuk and Ivotuk, two sites on the North Slope of Alaska. Additionally, metagenomes have been sequenced across a soil depth profile at both sites. There are significant differences between the two sites with regard to soil bulk density, pH, volumetric water content, total carbon, total phosphate, Iron III and methanogenesis potential. The sites are not significantly different in total organic matter, total nitrogen, Iron II and anaerobic respiration potential. Volumetric water content is highly correlated at both sites with soil bulk density, with higher water content measured at Ivotuk with finer, siltier soil, and lower water content measured at Atqasuk with coarser, sandier soil. The water retention in these soils may influence carbon dioxide and methane flux at these two sites. Incubations produced similar levels of carbon dioxide at both sites, and much higher levels of methane at Atqasuk than Ivotuk. Multiple regression analysis shows a strong correlation between volumetric water content and pH as predictor variables for methanogenesis in Ivotuk, though not in Atqasuk. Additionally, carbon dioxide production is significantly correlated with methane production in all samples and all depths, though there is a much stronger relationship in Atqasuk. This may indicate a relationship between methane oxidation and carbon dioxide production in Atqasuk, though further investigation is needed. Preliminary metagenomic data for Ivotuk indicates a possible relationship between iron reducing bacteria and soil iron concentrations. Further

  20. Helium process cycle

    SciTech Connect

    Ganni, Venkatarao

    2007-10-09

    A unique process cycle and apparatus design separates the consumer (cryogenic) load return flow from most of the recycle return flow of a refrigerator and/or liquefier process cycle. The refrigerator and/or liquefier process recycle return flow is recompressed by a multi-stage compressor set and the consumer load return flow is recompressed by an independent consumer load compressor set that maintains a desirable constant suction pressure using a consumer load bypass control valve and the consumer load return pressure control valve that controls the consumer load compressor's suction pressure. The discharge pressure of this consumer load compressor is thereby allowed to float at the intermediate pressure in between the first and second stage recycle compressor sets. Utilizing the unique gas management valve regulation, the unique process cycle and apparatus design in which the consumer load return flow is separate from the recycle return flow, the pressure ratios of each recycle compressor stage and all main pressures associated with the recycle return flow are allowed to vary naturally, thus providing a naturally regulated and balanced floating pressure process cycle that maintains optimal efficiency at design and off-design process cycle capacity and conditions automatically.

  1. Helium process cycle

    SciTech Connect

    Ganni, Venkatarao

    2008-08-12

    A unique process cycle and apparatus design separates the consumer (cryogenic) load return flow from most of the recycle return flow of a refrigerator and/or liquefier process cycle. The refrigerator and/or liquefier process recycle return flow is recompressed by a multi-stage compressor set and the consumer load return flow is recompressed by an independent consumer load compressor set that maintains a desirable constant suction pressure using a consumer load bypass control valve and the consumer load return pressure control valve that controls the consumer load compressor's suction pressure. The discharge pressure of this consumer load compressor is thereby allowed to float at the intermediate pressure in between the first and second stage recycle compressor sets. Utilizing the unique gas management valve regulation, the unique process cycle and apparatus design in which the consumer load return flow is separate from the recycle return flow, the pressure ratios of each recycle compressor stage and all main pressures associated with the recycle return flow are allowed to vary naturally, thus providing a naturally regulated and balanced floating pressure process cycle that maintains optimal efficiency at design and off-design process cycle capacity and conditions automatically.

  2. Menu Cycles.

    ERIC Educational Resources Information Center

    Clayton, Alfred; Almony, John

    The curriculum guide for commercial foods instruction is designed to aid the teacher in communicating the importance of menu cycles in commercial food production. It also provides information about the necessary steps in getting food from the raw form to the finished product, and then to the consumer. In addition to providing information on how to…

  3. Gonadotropin-releasing hormone agonist trigger is a better alternative than human chorionic gonadotropin in PCOS undergoing IVF cycles for an OHSS Free Clinic: A Randomized control trial

    PubMed Central

    Krishna, Deepika; Dhoble, Snehal; Praneesh, Gautham; Rathore, Suvarna; Upadhaya, Amit; Rao, Kamini

    2016-01-01

    OBJECTIVE: The objective of this study is to evaluate if gonadotropin-releasing hormone agonist (GnRHa) trigger is a better alternative to human chorionic gonadotropin (hCG) in polycystic ovary syndrome (PCOS) of Indian origin undergoing in vitro fertilization (IVF) cycles with GnRH antagonist for the prevention of ovarian hyperstimulation syndrome (OHSS). DESIGN: Prospective randomized control trial. SETTING: Tertiary care center. MATERIALS AND METHODS: A total of 227 patients diagnosed with PCOS, undergoing IVF in an antagonist protocol were recruited and randomly assigned into two groups: Group A (study group): GnRHa trigger 0.2 mg (n = 92) and Group B (control group): 250 μg of recombinant hCG as trigger (n = 101) 35 h before oocyte retrieval. We chose segmentation strategy, freezing all embryos in both the groups. STATISTICAL ANALYSIS: Continuous variables were expressed as mean ± standard deviation independent sample t-test and Kolmogorov-Smirnov test were used for continuous variables which were normally distributed and Mann-Whitney U-test for data not normally distributed. MAIN OUTCOME MEASURES: Primary outcome: OHSS (mild, moderate, and severe) rates. Secondary outcomes: Maturity rate of the oocytes, fertilization rate, availability of top quality embryos on day 3 (Grade 1 and Grade 2). RESULTS The incidence of moderate to severe OHSS in the hCG group was 37.6% and 0% in the GnRHa group with P < 0.001. The GnRHa group had significantly more mature oocytes retrieved (19.1 ± 11.7 vs. 14.1 ± 4.3), more fertilized oocytes (15.6 ± 5.6 vs. 11.7 ± 3.6), and a higher number of top quality cleavage embryos on day 3 (12.9 ± 4.7 vs. 7.5 ± 4.3) than the hCG group. CONCLUSIONS: The most effective strategy which significantly eliminates the occurrence of OHSS in PCOS following ovarian stimulation in antagonist IVF cycles is the use of GnRHa trigger yielding more mature oocytes and good quality embryos when compared with hCG trigger. PMID:27803584

  4. Biogeochemical controls on daily cycling of hydrochemistry and δ13C of dissolved inorganic carbon in a karst spring-fed pool

    NASA Astrophysics Data System (ADS)

    Jiang, Yongjun; Hu, Yijun; Schirmer, Mario

    2013-01-01

    SummaryVariations in temperature, photosynthesis and respiration can force daily variations in pH, DO and DIC in surface water, potentially driving calcite precipitation or dissolution of calcium carbonate. Diel cycles of hydrochemistry and δ13CDIC were measured at high time-resolution (1 h) to assess the relative magnitudes of biological and geochemical controls on carbonate chemistry and carbon cycling in a spring-fed pool with flourishing submerged plants in Chongqing, SW China under sunny weather. Results show that there were no diurnal variations in the physical and chemical parameters of the Shuifang spring water. However, during the daytime periods, SC, Ca2+, alkalinity, NO3- and pCO2 in the pool water decreased to less than those in the spring water, while pH, DO and δ13CDIC in the pool water became greater than those in the spring water. Conversely, during nighttime periods, pool water SC, Ca2+, alkalinity, NO3- and pCO2 returned to or even became greater than the spring water, while pH, DO and δ13CDIC decreased to less than the spring water. This work shows that photosynthesis and respiration of subaquatic communities are the dominant processes influencing the observed diel variations of hydrochemistry in karst spring-fed pool water. During the daytime, a simultaneous increase of δ13CDIC and DO, and decrease in DIC indicates that photosynthesis was the primary control on hydrochemistry of the pool water. Conversely, the water remained saturated with respect to calcite (SIc ranging from 0.04 to 0.15) and δ13CDIC values decreased at nighttime, indicating that respiration of the subaquatic community had a dominant influence over calcite dissolution and outgassing in the pool water. The total amount of DIC loss was estimated to be about 110,785 mmol/day which represented about 1.33 kg C/day. More specifically, the amount of DIC loss through carbonate precipitation was about 38,775 mmol/day (0.47 kg C/day), whereas photosynthetic uptake was about 60

  5. Biological and geochemical controls on diel dissolved inorganic carbon cycling in a low-order agricultural stream: implications for reach scales and beyond

    USGS Publications Warehouse

    Bohlke, Johnkarl F.; Tobias, Craig

    2011-01-01

    Movement of dissolved inorganic carbon (DIC) through the hydrologic cycle is an important component of global carbon budgets, but there is considerable uncertainty about the controls of DIC transmission from landscapes to streams, and through river networks to the oceans. In this study, diel measurements of DIC, d13C-DIC, dissolved oxygen (O2), d18O-O2, alkalinity, pH, and other parameters were used to assess the relative magnitudes of biological and geochemical controls on DIC cycling and flux in a nutrient-rich, net autotrophic stream. Rates of photosynthesis (P), respiration (R), groundwater discharge, air–water exchange of CO2, and carbonate precipitation/dissolution were quantified through a time-stepping chemical/isotope (12C and 13C, 16O and 18O) mass balance model. Groundwater was the major source of DIC to the stream. Primary production and carbonate precipitation were equally important sinks for DIC removed from the water column. The stream was always super-saturated with respect to carbonate minerals, but carbonate precipitation occurred mainly during the day when P increased pH. We estimated more than half (possibly 90%) of the carbonate precipitated during the day was retained in the reach under steady baseflow conditions. The amount of DIC removed from the overlying water through carbonate precipitation was similar to the amount of DIC generated from R. Air–water exchange of CO2 was always from the stream to the atmosphere, but was the smallest component of the DIC budget. Overall, the in-stream DIC reactions reduced the amount of CO2 evasion and the downstream flux of groundwater-derived DIC by about half relative to a hypothetical scenario with groundwater discharge only. Other streams with similar characteristics are widely distributed in the major river basins of North America. Data from USGS water quality monitoring networks from the 1960s to the 1990s indicated that 40% of 652 stream monitoring stations in the contiguous USA were at or above

  6. Biological and geochemical controls on diel dissolved inorganic carbon cycling in a low-order agricultural stream: Implications for reach scales and beyond

    USGS Publications Warehouse

    Tobias, C.; Böhlke, J.K.

    2011-01-01

    Movement of dissolved inorganic carbon (DIC) through the hydrologic cycle is an important component of global carbon budgets, but there is considerable uncertainty about the controls of DIC transmission from landscapes to streams, and through river networks to the oceans. In this study, diel measurements of DIC, ??13C-DIC, dissolved oxygen (O2), ??18O-O2, alkalinity, pH, and other parameters were used to assess the relative magnitudes of biological and geochemical controls on DIC cycling and flux in a nutrient-rich, net autotrophic stream. Rates of photosynthesis (P), respiration (R), groundwater discharge, air-water exchange of CO2, and carbonate precipitation/dissolution were quantified through a time-stepping chemical/isotope (12C and 13C, 16O and 18O) mass balance model. Groundwater was the major source of DIC to the stream. Primary production and carbonate precipitation were equally important sinks for DIC removed from the water column. The stream was always super-saturated with respect to carbonate minerals, but carbonate precipitation occurred mainly during the day when P increased pH. We estimated more than half (possibly 90%) of the carbonate precipitated during the day was retained in the reach under steady baseflow conditions. The amount of DIC removed from the overlying water through carbonate precipitation was similar to the amount of DIC generated from R. Air-water exchange of CO2 was always from the stream to the atmosphere, but was the smallest component of the DIC budget. Overall, the in-stream DIC reactions reduced the amount of CO2 evasion and the downstream flux of groundwater-derived DIC by about half relative to a hypothetical scenario with groundwater discharge only. Other streams with similar characteristics are widely distributed in the major river basins of North America. Data from USGS water quality monitoring networks from the 1960s to the 1990s indicated that 40% of 652 stream monitoring stations in the contiguous USA were at or above

  7. Quantifying the Adaptive Cycle.

    PubMed

    Angeler, David G; Allen, Craig R; Garmestani, Ahjond S; Gunderson, Lance H; Hjerne, Olle; Winder, Monika

    2015-01-01

    The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994-2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems. PMID:26716453

  8. Quantifying the adaptive cycle

    USGS Publications Warehouse

    Angeler, David G.; Allen, Craig R.; Garmestani, Ahjond S.; Gunderson, Lance H.; Hjerne, Olle; Winder, Monika

    2015-01-01

    The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

  9. Quantifying the Adaptive Cycle

    PubMed Central

    Angeler, David G.; Allen, Craig R.; Garmestani, Ahjond S.; Gunderson, Lance H.; Hjerne, Olle; Winder, Monika

    2015-01-01

    The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems. PMID:26716453

  10. Heterogeneous abnormalities of CCND1 and RB1 in primary cutaneous T-Cell lymphomas suggesting impaired cell cycle control in disease pathogenesis.

    PubMed

    Mao, Xin; Orchard, Guy; Vonderheid, Eric C; Nowell, Peter C; Bagot, Martine; Bensussan, Armand; Russell-Jones, Robin; Young, Bryan D; Whittaker, Sean J

    2006-06-01

    Upregulation of cyclin D1/B-cell leukemia/lymphoma 1 (CCND1/BCL1) is present in most mantle cell lymphomas with the t(11;14)(q13;q32) translocation. However, little is known about the abnormalities of CCND1 and its regulator RB1 in primary cutaneous T-cell lymphomas (CTCL). We analyzed CCND and RB status in CTCL using fluorescent in situ hybridization (FISH), immunohistochemistry (IHC), and Affymetrix expression microarray. FISH revealed loss of CCND1/BCL1 in five of nine Sézary syndrome (SS) cases but gain in two cases, and RB1 loss in four of seven SS cases. IHC showed absent CCND1/BCL1 expression in 18 of 30 SS, 10 of 23 mycosis fungoides (MF), and three of 10 primary cutaneous CD30+ anaplastic large-cell lymphoma (C-ALCL). Increased CCND1/BCL1 expression was seen in nine MF, seven C-ALCL, and six SS cases. Absent RB1 expression was detected in 8 of 12 MF and 7 of 9 SS cases, and raised RB1 expression in 7 of 8 C-ALCL. Affymetrix revealed increased gene expression of CCND2 in four of eight CTCL cases, CCND3 in three cases, and CDKN2C in two cases with a normal expression of CCND1 and RB1. These findings suggest heterogeneous abnormalities of CCND and RB in CTCL, in which dysregulated CCND and RB1 may lead to impaired cell cycle control.

  11. “Fit” inside the Work-Family Black Box: An Ecology of the Life Course, Cycles of Control Reframing1

    PubMed Central

    Moen, Phyllis; Kelly, Erin; Huang, Reiping

    2009-01-01

    Scholars have not fully theorized the multifaceted, interdependent dimensions within the work-family “black box.” Taking an ecology of the life course approach, we theorize common work-family and adequacy constructs as capturing different components of employees' cognitive appraisals of fit between their demands and resources at the interface between home and work. Employees' appraisals of their work-family linkages and of their relative resource adequacy are not made independently but, rather, co-occur as identifiable constellations of fit. The life course approach hypothesizes that shifts in objective demands/ resources at work and at home over the life course result in employees experiencing cycles of control, that is, corresponding shifts in their cognitive assessments of fit. We further theorize patterned appraisals of fit are key mediators between objective work-family conditions and employees' health, well-being and strategic adaptations. As a case example, we examine whether employees' assessments on ten dimensions cluster together as patterned fit constellations, using data from a middle-class sample of 753 employees working at Best Buy's corporate headquarters. We find no single linear construct of fit that captures the complexity within the work-family black box. Instead, respondents experience six distinctive constellations of fit: one optimal, two poor, and three moderate fit constellations. PMID:19809532

  12. Opposite OH reactivity and ozone cycles in the Amazon rainforest and megacity Beijing: Subversion of biospheric oxidant control by anthropogenic emissions

    NASA Astrophysics Data System (ADS)

    Williams, Jonathan; Keßel, Stephan U.; Nölscher, Anke C.; Yang, Yudong; Lee, Yue; Yáñez-Serrano, Ana Maria; Wolff, Stefan; Kesselmeier, Jürgen; Klüpfel, Thomas; Lelieveld, Jos; Shao, Min

    2016-01-01

    The Amazon rainforest in Brazil and the megacity of Beijing in China are two of the most strongly contrasting habitats on Earth. In both locations, volatile chemicals are emitted into the atmosphere affecting the local atmospheric chemistry, air quality and ecosystem health. In this study, the total reactivity in air available for reaction with the atmosphere's primary oxidant the OH radical, has been measured directly in both locations along with individual volatile organic compounds(VOC), nitrogen oxides(NOx), ozone(O3) and carbon dioxide(CO2). Peak daily OH-reactivity in the Amazon 72 s-1, (min. 27 s-1) was approximately three times higher than Beijing 26 s-1 (min. 15 s-1). However, diel ozone variation in Amazonia was small (˜5 ppb) whereas in Beijing ˜70 ppb harmful photochemical ozone was produced by early afternoon. Amazon OH-reactivity peaked by day, was strongly impacted by isoprene, and anticorrelated to CO2, whereas in Beijing OH-reactivity was higher at night rising to a rush hour peak, was dominated by NO2 and correlated with CO2. These converse diel cycles between urban and natural ecosystems demonstrate how biosphere control of the atmospheric environment is subverted by anthropogenic emissions.

  13. The role of environmental controls in determining sardine and anchovy population cycles in the California Current: Analysis of an end-to-end model

    NASA Astrophysics Data System (ADS)

    Fiechter, Jerome; Rose, Kenneth A.; Curchitser, Enrique N.; Hedstrom, Katherine S.

    2015-11-01

    Sardine and anchovy are two forage species of particular interest because of their low-frequency cycles in adult abundance in boundary current regions, combined with a commercially relevant contribution to the global marine food catch. While several hypotheses have been put forth to explain decadal shifts in sardine and anchovy populations, a mechanistic basis for how the physics, biogeochemistry, and biology combine to produce patterns of synchronous variability across widely separated systems has remained elusive. The present study uses a 50-year (1959-2008) simulation of a fully coupled end-to-end ecosystem model configured for sardine and anchovy in the California Current System to investigate how environmental processes control their population dynamics. The results illustrate that slightly different temperature and diet preferences can lead to significantly different responses to environmental variability. Simulated adult population fluctuations are associated with age-1 growth (via age-2 egg production) and prey availability for anchovy, while they depend primarily on age-0 survival and temperature for sardine. The analysis also hints at potential linkages to known modes of climate variability, whereby changes in adult abundance are related to ENSO for anchovy and to the PDO for sardine. The connection to the PDO and ENSO is consistent with modes of interannual and decadal variability that would alternatively favor anchovy during years of cooler temperatures and higher prey availability, and sardine during years of warmer temperatures and lower prey availability. While the end-to-end ecosystem model provides valuable insight on potential relationships between environmental conditions and sardine and anchovy population dynamics, understanding the complex interplay, and potential lags, between the full array of processes controlling their abundances in the California Current System remains an on-going challenge.

  14. The history of hepatitis C virus (HCV): Basic research reveals unique features in phylogeny, evolution and the viral life cycle with new perspectives for epidemic control.

    PubMed

    Bukh, Jens

    2016-10-01

    The discovery of hepatitis C virus (HCV) in 1989 permitted basic research to unravel critical components of a complex life cycle for this important human pathogen. HCV is a highly divergent group of viruses classified in 7 major genotypes and a great number of subtypes, and circulating in infected individuals as a continuously evolving quasispecies destined to escape host immune responses and applied antivirals. Despite the inability to culture patient viruses directly in the laboratory, efforts to define the infectious genome of HCV resulted in development of experimental recombinant in vivo and in vitro systems, including replicons and infectious cultures in human hepatoma cell lines. And HCV has become a model virus defining new paradigms in virology, immunology and biology. For example, HCV research discovered that a virus could be completely dependent on microRNA for its replication since microRNA-122 is critical for the HCV life cycle. A number of other host molecules critical for HCV entry and replication have been identified. Thus, basic HCV research revealed important molecules for development of host targeting agents (HTA). The identification and characterization of HCV encoded proteins and their functional units contributed to the development of highly effective direct acting antivirals (DAA) against the NS3 protease, NS5A and the NS5B polymerase. In combination, these inhibitors have since 2014 permitted interferon-free therapy with cure rates above 90% among patients with chronic HCV infection; however, viral resistance represents a challenge. Worldwide control of HCV will most likely require the development of a prophylactic vaccine, and numerous candidates have been pursued. Research characterizing features critical for antibody-based virus neutralization and T cell based virus elimination from infected cells is essential for this effort. If the world community promotes an ambitious approach by applying current DAA broadly, continues to develop

  15. The history of hepatitis C virus (HCV): Basic research reveals unique features in phylogeny, evolution and the viral life cycle with new perspectives for epidemic control.

    PubMed

    Bukh, Jens

    2016-10-01

    The discovery of hepatitis C virus (HCV) in 1989 permitted basic research to unravel critical components of a complex life cycle for this important human pathogen. HCV is a highly divergent group of viruses classified in 7 major genotypes and a great number of subtypes, and circulating in infected individuals as a continuously evolving quasispecies destined to escape host immune responses and applied antivirals. Despite the inability to culture patient viruses directly in the laboratory, efforts to define the infectious genome of HCV resulted in development of experimental recombinant in vivo and in vitro systems, including replicons and infectious cultures in human hepatoma cell lines. And HCV has become a model virus defining new paradigms in virology, immunology and biology. For example, HCV research discovered that a virus could be completely dependent on microRNA for its replication since microRNA-122 is critical for the HCV life cycle. A number of other host molecules critical for HCV entry and replication have been identified. Thus, basic HCV research revealed important molecules for development of host targeting agents (HTA). The identification and characterization of HCV encoded proteins and their functional units contributed to the development of highly effective direct acting antivirals (DAA) against the NS3 protease, NS5A and the NS5B polymerase. In combination, these inhibitors have since 2014 permitted interferon-free therapy with cure rates above 90% among patients with chronic HCV infection; however, viral resistance represents a challenge. Worldwide control of HCV will most likely require the development of a prophylactic vaccine, and numerous candidates have been pursued. Research characterizing features critical for antibody-based virus neutralization and T cell based virus elimination from infected cells is essential for this effort. If the world community promotes an ambitious approach by applying current DAA broadly, continues to develop

  16. Seclusion and the lunar cycles.

    PubMed

    Mason, T

    1997-06-01

    1. The lunar cycle's influence over psychological disturbances in the human being is known as the Transylvanian effect. 2. Seclusion is used predominantly for the control and management of violence and aggression in patients. 3. If the Transylvanian effect is supported, a relationship between lunar cycles and the use of seclusion should exist; no such correlation, however, was found in this study. PMID:9189846

  17. How do prokaryotic cells cycle?

    PubMed

    Margolin, William; Bernander, Rolf

    2004-09-21

    This issue of Current Biology features five reviews covering various key aspects of the eukaryotic cell cycle. The topics include initiation of chromosome replication, assembly of the mitotic spindle, cytokinesis, the regulation of cell-cycle progression, and cell-cycle modeling, focusing mainly on budding yeast, fission yeast and animal cell model systems. The reviews underscore common themes as well as key differences in the way these processes are carried out and regulated among the different model organisms. Consequently, an important question is how cell-cycle mechanisms and controls have evolved, particularly in the broader perspective of the three domains of life.

  18. A high response to controlled ovarian stimulation induces premature luteinization with a negative impact on pregnancy outcomes in a gonadotropin-releasing hormone antagonist cycle

    PubMed Central

    Koo, Hwa Seon; Cha, Sun Hwa; Kim, Hye Ok; Song, In Ok; Min, Eung Gi; Yang, Kwang Moon

    2015-01-01

    Objective The goal of this study was to investigate the relationship between serum progesterone (P4) levels on the day of human chorionic gonadotropin (hCG) administration and the pregnancy rate among women undergoing controlled ovarian stimulation for in vitro fertilization (IVF) or intracytoplasmic sperm injection-embryo transfer (ICSI-ET) using a flexible antagonist protocol. Methods This prospective study included 200 IVF and ICSI-ET cycles in which a flexible antagonist protocol was used. The patients were divided into five distinct groups according to their serum P4 levels at the time of hCG administration (0.80, 0.85, 0.90, 0.95, and 1.00 ng/mL). The clinical pregnancy rate (CPR) was calculated for each P4 interval. Statistically significant differences were observed at a serum P4 level of 0.9 ng/mL. These data suggest that a serum P4 concentration of 0.9 ng/mL may represent the optimal threshold level for defining premature luteinization (PL) based on the presence of a significant negative impact on the CPR. Results The CPR for each round of ET was significantly lower in the PL group defined using this threshold (25.8% vs. 41.8%; p=0.019), and the number of oocytes retrieved was significantly higher than in the non-PL group (17.3±7.2 vs. 11.0±7.2; p=0.001). Elevated serum P4 levels on the day of hCG administration were associated with a reduced CPR, despite the retrieval of many oocytes. Conclusion Measuring serum P4 values at the time of hCG administration is necessary in order to determine the optimal strategy for embryo transfer. PMID:26816874

  19. Physalis floridana Cell Number Regulator1 encodes a cell membrane-anchored modulator of cell cycle and negatively controls fruit size

    PubMed Central

    Li, Zhichao; He, Chaoying

    2015-01-01

    Physalis species show a significant variation in berry size; however, the underlying molecular basis is unknown. In this work, we showed that cell division difference in the ovaries might contribute to the ultimate berry size variation within Physalis species, and that mRNA abundance of Physalis floridana Cell Number Regulator1 (PfCNR1), the putative orthologue of the tomato fruit weight 2.2 (FW2.2), was negatively correlated with cell division in the ovaries. Moreover, heterochronic expression variation of the PfCNR1 genes in the ovaries concomitantly correlated with berry weight variation within Physalis species. In transgenic Physalis, multiple organ sizes could be negatively controlled by altering PfCNR1 levels, and cell division instead of cell expansion was primarily affected. PfCNR1 was shown to be anchored in the plasma membrane and to interact with PfAG2 (an AGAMOUS-like protein determining ovary identity). The expression of PfCYCD2;1, a putative orthologue of the mitosis-specific gene CyclinD2;1 in the cell cycle was negatively correlated with the PfCNR1 mRNA levels. PfAG2 was found to selectively bind to the CArG-box in the PfCYCD2;1 promoter and to repress PfCYCD2;1 expression, thus suggesting a PfAG2-mediated pathway for PfCNR1 to regulate cell division. The interaction of PfCNR1 with PfAG2 enhanced the repression of PfCYCD2;1 expression. The nuclear import of PfAG2 was essential in the proposed pathway. Our data provide new insights into the developmental pathways of a cell membrane-anchored protein that modulates cell division and governs organ size determination. This study also sheds light on the link between organ identity and organ growth in plants. PMID:25305759

  20. Physalis floridana Cell Number Regulator1 encodes a cell membrane-anchored modulator of cell cycle and negatively controls fruit size.

    PubMed

    Li, Zhichao; He, Chaoying

    2015-01-01

    Physalis species show a significant variation in berry size; however, the underlying molecular basis is unknown. In this work, we showed that cell division difference in the ovaries might contribute to the ultimate berry size variation within Physalis species, and that mRNA abundance of Physalis floridana Cell Number Regulator1 (PfCNR1), the putative orthologue of the tomato fruit weight 2.2 (FW2.2), was negatively correlated with cell division in the ovaries. Moreover, heterochronic expression variation of the PfCNR1 genes in the ovaries concomitantly correlated with berry weight variation within Physalis species. In transgenic Physalis, multiple organ sizes could be negatively controlled by altering PfCNR1 levels, and cell division instead of cell expansion was primarily affected. PfCNR1 was shown to be anchored in the plasma membrane and to interact with PfAG2 (an AGAMOUS-like protein determining ovary identity). The expression of PfCYCD2;1, a putative orthologue of the mitosis-specific gene CyclinD2;1 in the cell cycle was negatively correlated with the PfCNR1 mRNA levels. PfAG2 was found to selectively bind to the CArG-box in the PfCYCD2;1 promoter and to repress PfCYCD2;1 expression, thus suggesting a PfAG2-mediated pathway for PfCNR1 to regulate cell division. The interaction of PfCNR1 with PfAG2 enhanced the repression of PfCYCD2;1 expression. The nuclear import of PfAG2 was essential in the proposed pathway. Our data provide new insights into the developmental pathways of a cell membrane-anchored protein that modulates cell division and governs organ size determination. This study also sheds light on the link between organ identity and organ growth in plants.

  1. Dynamic Modeling and Plantwide Control of a Hybrid Power and Chemical Plant: An Integrated Gasification Combined Cycle Coupled with a Methanol Plant

    NASA Astrophysics Data System (ADS)

    Robinson, Patrick J.

    Gasification has been used in industry on a relatively limited scale for many years, but it is emerging as the premier unit operation in the energy and chemical industries. The switch from expensive and insecure petroleum to solid hydrocarbon sources (coal and biomass) is occurring due to the vast amount of domestic solid resources, national security and global warming issues. Gasification (or partial oxidation) is a vital component of "clean coal" technology. Sulfur and nitrogen emissions can be reduced, overall energy efficiency is increased and carbon dioxide recovery and sequestration are facilitated. Gasification units in an electric power generation plant produce a fuel gas for driving combustion turbines. Gasification units in a chemical plant generate synthesis gas, which can be used to produce a wide spectrum of chemical products. Future plants are predicted to be hybrid power/chemical plants with gasification as the key unit operation. The coupling of an Integrated Gasification Combined Cycle (IGCC) with a methanol plant can handle swings in power demand by diverting hydrogen gas from a combustion turbine and synthesis gas from the gasifier to a methanol plant for the production of an easily-stored, hydrogen-consuming liquid product. An additional control degree of freedom is provided with this hybrid plant, fundamentally improving the controllability of the process. The idea is to base-load the gasifier and use the more responsive gas-phase units to handle disturbances. During the summer days, power demand can fluctuate up to 50% over a 12-hour period. The winter provides a different problem where spikes of power demand can go up 15% within the hour. The following dissertation develops a hybrid IGCC / methanol plant model, validates the steady-state results with a National Energy Technical Laboratory study, and tests a proposed control structure to handle these significant disturbances. All modeling was performed in the widely used chemical process

  2. Cytoplasmic-nuclear trafficking of G1/S cell cycle molecules and adult human β-cell replication: a revised model of human β-cell G1/S control.

    PubMed

    Fiaschi-Taesch, Nathalie M; Kleinberger, Jeffrey W; Salim, Fatimah G; Troxell, Ronnie; Wills, Rachel; Tanwir, Mansoor; Casinelli, Gabriella; Cox, Amy E; Takane, Karen K; Srinivas, Harish; Scott, Donald K; Stewart, Andrew F

    2013-07-01

    Harnessing control of human β-cell proliferation has proven frustratingly difficult. Most G1/S control molecules, generally presumed to be nuclear proteins in the human β-cell, are in fact constrained to the cytoplasm. Here, we asked whether G1/S molecules might traffic into and out of the cytoplasmic compartment in association with activation of cell cycle progression. Cdk6 and cyclin D3 were used to drive human β-cell proliferation and promptly translocated into the nucleus in association with proliferation. In contrast, the cell cycle inhibitors p15, p18, and p19 did not alter their location, remaining cytoplasmic. Conversely, p16, p21, and p27 increased their nuclear frequency. In contrast once again, p57 decreased its nuclear frequency. Whereas proliferating β-cells contained nuclear cyclin D3 and cdk6, proliferation generally did not occur in β-cells that contained nuclear cell cycle inhibitors, except p21. Dynamic cytoplasmic-nuclear trafficking of cdk6 was confirmed using green fluorescent protein-tagged cdk6 and live cell imaging. Thus, we provide novel working models describing the control of cell cycle progression in the human β-cell. In addition to known obstacles to β-cell proliferation, cytoplasmic-to-nuclear trafficking of G1/S molecules may represent an obstacle as well as a therapeutic opportunity for human β-cell expansion. PMID:23493571

  3. Defects in a New Class of Sulfate/Anion Transporter Link Sulfur Acclimation Responses to Intracellular Glutathione Levels and Cell Cycle Control1[W][OPEN

    PubMed Central

    Fang, Su-Chiung; Chung, Chin-Lin; Chen, Chun-Han; Lopez-Paz, Cristina; Umen, James G.

    2014-01-01

    We previously identified a mutation, suppressor of mating type locus3 15-1 (smt15-1), that partially suppresses the cell cycle defects caused by loss of the retinoblastoma tumor suppressor-related protein encoded by the MAT3 gene in Chlamydomonas reinhardtii. smt15-1 single mutants were also found to have a cell cycle defect leading to a small-cell phenotype. SMT15 belongs to a previously uncharacterized subfamily of putative membrane-localized sulfate/anion transporters that contain a sulfate transporter domain and are found in a widely distributed subset of eukaryotes and bacteria. Although we observed that smt15-1 has a defect in acclimation to sulfur-limited growth conditions, sulfur acclimation (sac) mutants, which are more severely defective for acclimation to sulfur limitation, do not have cell cycle defects and cannot suppress mat3. Moreover, we found that smt15-1, but not sac mutants, overaccumulates glutathione. In wild-type cells, glutathione fluctuated during the cell cycle, with highest levels in mid G1 phase and lower levels during S and M phases, while in smt15-1, glutathione levels remained elevated during S and M. In addition to increased total glutathione levels, smt15-1 cells had an increased reduced-to-oxidized glutathione redox ratio throughout the cell cycle. These data suggest a role for SMT15 in maintaining glutathione homeostasis that impacts the cell cycle and sulfur acclimation responses. PMID:25361960

  4. Nuclear Fuel Cycle

    SciTech Connect

    Dale, Deborah J.

    2014-10-28

    These slides will be presented at the training course “International Training Course on Implementing State Systems of Accounting for and Control (SSAC) of Nuclear Material for States with Small Quantity Protocols (SQP),” on November 3-7, 2014 in Santa Fe, New Mexico. The slides provide a basic overview of the Nuclear Fuel Cycle. This is a joint training course provided by NNSA and IAEA.

  5. Your Menstrual Cycle

    MedlinePlus

    ... during your menstrual cycle What happens during your menstrual cycle The menstrual cycle includes not just your period, but the rise ... tool is based on a sample 28-day menstrual cycle, but every woman is different in how long ...

  6. CDK6-a review of the past and a glimpse into the future: from cell-cycle control to transcriptional regulation.

    PubMed

    Tigan, A-S; Bellutti, F; Kollmann, K; Tebb, G; Sexl, V

    2016-06-16

    The G1 cell-cycle kinase CDK6 has long been thought of as a redundant homolog of CDK4. Although the two kinases have very similar roles in cell-cycle progression, it has recently become apparent that they differ in tissue-specific functions and contribute differently to tumor development. CDK6 is directly involved in transcription in tumor cells and in hematopoietic stem cells. These functions point to a role of CDK6 in tissue homeostasis and differentiation that is partially independent of CDK6's kinase activity and is not shared with CDK4. We review the literature on the contribution of CDK6 to transcription in an attempt to link the new findings on CDK6's transcriptional activity to cell-cycle progression. Finally, we note that anticancer therapies based on the inhibition of CDK6 kinase activity fail to take into account its kinase-independent role in tumor development.

  7. Progesterone change in the late follicular phase affects pregnancy rates both agonist and antagonist protocols in normoresponders: a case-controlled study in ICSI cycles

    PubMed Central

    Demir, Berfu; Kahyaoglu, Inci; Guvenir, Altay; Yerebasmaz, Neslihan; Altinbas, Sadiman; Dilbaz, Berna; Dilbaz, Serdar; Mollamahmutoglu, Leyla

    2016-01-01

    Abstract Objective: The aim of the presented study is to investigate the impact of progesterone change in the late follicular phase on the pregnancy rates of both agonist and antagonist protocols in normoresponders. Study design: A total of 201 normoresponder patients, who underwent embryo transfer were consecutively selected. 118 patients were stimulated using a long luteal GnRH agonist protocol and 83 using a flexible antagonist protocol. The level of change in late follicular phase progesterone was calculated according to the progesterone levels on the hCG day and pre-hCG day (1 or 2 days prior to hCG day) measurement. Results: Clinical pregnancy rates were comparable between long luteal and antagonist group (35.6 and 41%, respectively). The incidence of progesterone elevation on the hCG day was 11% in long luteal and 18% in antagonist group (p = 0.16). In pregnant cycles, p levels both on the hCG day and pre-hCG day measurement were significantly higher in antagonist than agonist cycles (p = 0.029, p = 0.038, respectively). The change of p level was statistically significant in non-pregnant cycles both for the agonist (-0.17 ± 0.07; 95% CI: −0.29 to −0.37) and antagonist groups (−0.18 ± 0.07; 95%CI: −0.31 to −0.04). Conclusions: Late follicular phase progesterone levels were stable during the cycles of pregnant patients irrespective of the protocols and were shown to be higher in pregnant patients in antagonist cycles when compared to agonist cycles. PMID:26654315

  8. Hydrological cycle.

    PubMed

    Gonçalves, H C; Mercante, M A; Santos, E T

    2011-04-01

    The Pantanal hydrological cycle holds an important meaning in the Alto Paraguay Basin, comprising two areas with considerably diverse conditions regarding natural and water resources: the Plateau and the Plains. From the perspective of the ecosystem function, the hydrological flow in the relationship between plateau and plains is important for the creation of reproductive and feeding niches for the regional biodiversity. In general, river declivity in the plateau is 0.6 m/km while declivity on the plains varies from 0.1 to 0.3 m/km. The environment in the plains is characteristically seasonal and is home to an exuberant and abundant diversity of species, including some animals threatened with extinction. When the flat surface meets the plains there is a diminished water flow on the riverbeds and, during the rainy season the rivers overflow their banks, flooding the lowlands. Average annual precipitation in the Basin is 1,396 mm, ranging from 800 mm to 1,600 mm, and the heaviest rainfall occurs in the plateau region. The low drainage capacity of the rivers and lakes that shape the Pantanal, coupled with the climate in the region, produce very high evaporation: approximately 60% of all the waters coming from the plateau are lost through evaporation. The Alto Paraguay Basin, including the Pantanal, while boasting an abundant availability of water resources, also has some spots with water scarcity in some sub-basins, at different times of the year. Climate conditions alone are not enough to explain the differences observed in the Paraguay River regime and some of its tributaries. The complexity of the hydrologic regime of the Paraguay River is due to the low declivity of the lands that comprise the Mato Grosso plains and plateau (50 to 30 cm/km from east to west and 3 to 1.5 cm/km from north to south) as well as the area's dimension, which remains periodically flooded with a large volume of water. PMID:21537597

  9. An introduction to global carbon cycle management

    USGS Publications Warehouse

    Sundquist, Eric T.; Ackerman, Katherine V.; Parker, Lauren; Huntzinger, Deborah N.

    2009-01-01

    Past and current human activities have fundamentally altered the global carbon cycle. Potential future efforts to control atmospheric CO2 will also involve significant changes in the global carbon cycle. Carbon cycle scientists and engineers now face not only the difficulties of recording and understanding past and present changes but also the challenge of providing information and tools for new management strategies that are responsive to societal needs. The challenge is nothing less than managing the global carbon cycle.

  10. Comparison of oxygen uptake during cycle ergometry with and without functional electrical stimulation in patients with COPD: protocol for a randomised, single-blind, placebo-controlled, cross-over trial

    PubMed Central

    Medrinal, Clément; Prieur, Guillaume; Debeaumont, David; Robledo Quesada, Aurora; Combret, Yann; Quieffin, Jean; Contal, Olivier; Lamia, Bouchra

    2016-01-01

    Introduction Chronic obstructive pulmonary disease (COPD) has systemic repercussions that can lead to peripheral muscle dysfunction. Muscle atrophy reduces aerobic capacity, greatly limiting activities of daily living and quality of life. Pulmonary rehabilitation is the gold standard treatment for these patients, however, patients may not be able to reach sufficient training intensities for benefits to occur. Technologies such as functional electrical stimulation (FES) are currently being adapted and tested to enhance exercise training. We hypothesise that FES coupled with cycling (FES-cycling) will improve maximal uptake of oxygen (VO2) and aerobic capacity more than endurance training with placebo stimulation. Methods A randomised, single-blind, placebo-controlled crossover trial will be carried out to evaluate the effects of FES-cycling on VO2 during endurance exercise on a cycle ergometer in patients with COPD. 25 patients with COPD will carry out two 30 min sessions at a constant load; one session with active and one with placebo FES. The primary outcome is oxygen uptake recorded with a metabolic measurement system. Secondary outcomes include ventilation equivalent for oxygen, ventilation equivalent for carbon dioxide, cardiac output, lactate values, perceived dyspnoea and perceived muscle fatigue. Results and conclusions Approval has been granted by our Institutional Review Board (Comité de Protection des Personnes Nord-Ouest 3). The results of the trial will be presented at national and international meetings and published in peer-reviewed journals. Trial registration number NCT02594722. PMID:27110364

  11. On the effect of deep-rolling and laser-peening on the stress-controlled low- and high-cycle fatigue behavior of Ti-6Al-4V at elevated temperatures up to 550?C

    SciTech Connect

    Ritchie, IAltenberger, RKNalla, YSano LWagner, RO

    2012-04-01

    The effect of surface treatment on the stress/life fatigue behavior of a titanium Ti-6Al-4V turbine fan blade alloy is investigated in the regime of 102 to 106 cycles to failure under fully reversed stress-controlled isothermal push-pull loading between 25? and 550?C at a frequency of 5 Hz. Specifically, the fatigue behavior was examined in specimens in the deep-rolled and laser-shock peened surface conditions, and compared to results on samples in the untreated (machined and stress annealed) condition. Although the fatigue resistance of the Ti-6Al-4V alloy declined with increasing test temperature regardless of surface condition, deep-rolling and laser-shock peening surface treatments were found to extend the fatigue lives by factors of more than 30 and 5-10, respectively, in the high-cycle and low-cycle fatigue regimes at temperatures as high as 550?C. At these temperatures, compressive residual stresses are essentially relaxed; however, it is the presence of near-surface work hardened layers, with a nanocystalline structure in the case of deep-rolling and dense dislocation tangles in the case of laser-shock peening, which remain fairly stable even after cycling at 450?-550?C, that provide the basis for the beneficial role of mechanical surface treatments on the fatigue strength of Ti-6Al-4V at elevated temperatures.

  12. Antiphase light and temperature cycles affect PHYTOCHROME B-controlled ethylene sensitivity and biosynthesis, limiting leaf movement and growth of Arabidopsis.

    PubMed

    Bours, Ralph; van Zanten, Martijn; Pierik, Ronald; Bouwmeester, Harro; van der Krol, Alexander

    2013-10-01

    In the natural environment, days are generally warmer than the night, resulting in a positive day/night temperature difference (+DIF). Plants have adapted to these conditions, and when exposed to antiphase light and temperature cycles (cold photoperiod/warm night [-DIF]), most species exhibit reduced elongation growth. To study the physiological mechanism of how light and temperature cycles affect plant growth, we used infrared imaging to dissect growth dynamics under +DIF and -DIF in the model plant Arabidopsis (Arabidopsis thaliana). We found that -DIF altered leaf growth patterns, decreasing the amplitude and delaying the phase of leaf movement. Ethylene application restored leaf growth in -DIF conditions, and constitutive ethylene signaling mutants maintain robust leaf movement amplitudes under -DIF, indicating that ethylene signaling becomes limiting under these conditions. In response to -DIF, the phase of ethylene emission advanced 2 h, but total ethylene emission was not reduced. However, expression analysis on members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase ethylene biosynthesis gene family showed that ACS2 activity is specifically suppressed in the petiole region under -DIF conditions. Indeed, petioles of plants under -DIF had reduced ACC content, and application of ACC to the petiole restored leaf growth patterns. Moreover, acs2 mutants displayed reduced leaf movement under +DIF, similar to wild-type plants under -DIF. In addition, we demonstrate that the photoreceptor PHYTOCHROME B restricts ethylene biosynthesis and constrains the -DIF-induced phase shift in rhythmic growth. Our findings provide a mechanistic insight into how fluctuating temperature cycles regulate plant growth.

  13. Polysulfide shuttle control: Towards a lithium-sulfur battery with superior capacity performance up to 1000 cycles by matching the sulfur/electrolyte loading

    NASA Astrophysics Data System (ADS)

    Cheng, Xin-Bing; Huang, Jia-Qi; Peng, Hong-Jie; Nie, Jing-Qi; Liu, Xin-Yan; Zhang, Qiang; Wei, Fei

    2014-05-01

    Lithium-sulfur battery is one of the most promising alternative power sources, but the polysulfide shuttle between the anode and cathode induces low Coulombic efficiency, low utilization of the sulfur cathode, and severe degradation of cycle life. Herein, the polysulfide shuttle was tuned by the loading of sulfur and electrolyte in a Li-S cell. A lithium-sulfur cell with a high initial discharge capacity of 1053 mAh g-1 at a high rate of 1 C and an ultralow decay rate of 0.049%/per cycle during 1000 cycles was obtained by using carbon nanotube@sulfur cathode and suppressing polysulfide shuttle to a shuttle factor of 0.02 by matching the sulfur/electrolyte loading. The use of matching the sulfur/electrolyte loading is a facile way to tune the shuttle of polysulfide, which provides not only new insights to the energy chemistry of Li/S batteries, but also important principle to assemble a Li/S cell with recommend loading for their commercialization application in portable mobile devices and electric vehicles.

  14. Identification and functional analysis of hPRP17, the human homologue of the PRP17/CDC40 yeast gene involved in splicing and cell cycle control.

    PubMed Central

    Ben Yehuda, S; Dix, I; Russell, C S; Levy, S; Beggs, J D; Kupiec, M

    1998-01-01

    The PRP17 gene of the yeast Saccharomyces cerevisiae encodes a protein that participates in the second step of the splicing reaction. It was found recently that the yeast PRP17 gene is identical to the cell division cycle CDC40 gene. The PRP17/CDC40 gene codes for a protein with several copies of the WD repeat, a motif found in a large family of proteins that play important roles in signal transduction, cell cycle progression, splicing, transcription, and development. In this report, we describe the identification of human, nematode, and fission yeast homologues of the PRP17/CDC40 gene of S. cerevisiae. The newly identified proteins share homology with the budding yeast protein throughout their entire sequence, with the similarity being greatest in the C-terminal two thirds that includes the conserved WD repeats. We show that a yeast-human chimera, carrying the C-terminal two thirds of the hPRP17 protein, is able to complement the cell cycle and splicing defects of a yeast prp17 mutant. Moreover, the yeast and yeast-human chimeric proteins co-precipitate the intron-exon 2 lariat intermediate and the intron lariat product, providing evidence that these proteins are spliceosome-associated. These results show the functional conservation of the Prp17 proteins in evolution and suggest that the second step of splicing takes place by a similar mechanism throughout eukaryotes. PMID:9769104

  15. Dosage of Dyrk1a shifts cells within a p21-cyclin D1 signaling map to control the decision to enter the cell cycle.

    PubMed

    Chen, Jia-Yun; Lin, Jia-Ren; Tsai, Feng-Chiao; Meyer, Tobias

    2013-10-10

    Mammalian cells have a remarkable capacity to compensate for heterozygous gene loss or extra gene copies. One exception is Down syndrome (DS), where a third copy of chromosome 21 mediates neurogenesis defects and lowers the frequency of solid tumors. Here we combine live-cell imaging and single-cell analysis to show that increased dosage of chromosome 21-localized Dyrk1a steeply increases G1 cell cycle duration through direct phosphorylation and degradation of cyclin D1 (CycD1). DS-derived fibroblasts showed analogous cell cycle changes that were reversed by Dyrk1a inhibition. Furthermore, reducing Dyrk1a activity increased CycD1 expression to force a bifurcation, with one subpopulation of cells accelerating proliferation and the other arresting proliferation by costabilizing CycD1 and the CDK inhibitor p21. Thus, dosage of Dyrk1a repositions cells within a p21-CycD1 signaling map, directing each cell to either proliferate or to follow two distinct cell cycle exit pathways characterized by high or low CycD1 and p21 levels. PMID:24119401

  16. Luteal phase support with estradiol and progesterone versus progesterone alone in GnRH antagonist ICSI cycles: a randomized controlled study.

    PubMed

    Ismail Madkour, Wael A; Noah, Bassel; Abdel Hamid, Amr M S; Zaheer, Hena; Al-Bahr, Awatif; Shaeer, Mahmoud; Moawad, Ashraf

    2016-06-01

    In vitro fertilization (IVF) cycles are associated with a defective luteal phase. Although progesterone supplementation to treat this problem is standard practice, estrogen addition is debatable. Our aim was to compare pregnancy outcomes in 220 patients undergoing antagonist intracytoplasmic sperm injection (ICSI) cycles protocol. The patients were randomly assigned into two equal groups to receive either vaginal progesterone alone (90 mg once daily) starting on the day of oocyte retrieval for up to 12 weeks if pregnancy occurred or estradiol addition (2 mg twice daily) starting on the same day and continuing up to seven weeks (foetal viability scan). Primary outcomes were pregnancy and ongoing pregnancy rates per embryo transfer. Secondary outcomes were implantation and early pregnancy loss rates. Pregnancy rates showed no significant difference between group 1 (39.09%) and 2 (43.63%) (p value = 0.3). Similarly, both groups were comparable regarding ongoing pregnancy rate (32.7% group 1 and 36.3% group 2, p value = 0.1). Implantation rates showed no difference between group 1 (19.25%) and group 2 (23.44%) (p value = 0.2). Early pregnancy loss rates were comparable, with 6.3% and 7.2% in groups 1 and 2, respectively, (p value = 0.4). In conclusion, the addition of 4 mg estrogen daily to progesterone for luteal support in antagonist ICSI cycles is not beneficial for pregnancy outcome. PMID:27434094

  17. Attenuation of G{sub 2} cell cycle checkpoint control in human tumor cells is associated with increased frequencies of unrejoined chromosome breaks but not increased cytotoxicity following radiation exposure

    SciTech Connect

    Schwartz, J.L.; Cowan, J.; Grdina, D.J.

    1997-08-01

    The contribution of G{sub 2} cell cycle checkpoint control to ionizing radiation responses was examined in ten human tumor cell lines. Most of the delay in cell cycle progression seen in the first cell cycle following radiation exposure was due to blocks in G{sub 2} and there were large cell line-to-cell line variations in the length of the G{sub 2} block. Longer delays were seen in cell lines that had mutations in p53. There was a highly significant inverse correlation between the length of G{sub 2} delay and the frequency of unrejoined chromosome breaks seen as chromosome terminal deletions in mitosis, and observation that supports the hypothesis that the signal for G{sub 2} delay in mammalian cells is an unrejoined chromosome break. There were also an inverse correlation between the length of G{sub 2} delay and the level of chromosome aneuploidy in each cell line, suggesting that the G{sub 2} and mitotic spindel checkpoints may be linked to each other. Attenuation in G{sub 2} checkpoint control was not associated with alterations in either the frequency of induced chromosome rearrangements or cell survival following radiation exposure suggesting that chromosome rearrangements, the major radiation-induced lethal lesion in tumor cells, form before cells enters G{sub 2}. Thus, agents that act solely to override G{sub 2} arrest should produce little radiosensitization in human tumor cells.

  18. Bi-modal Distribution of the Second Messenger c-di-GMP Controls Cell Fate and Asymmetry during the Caulobacter Cell Cycle

    PubMed Central

    Abel, Sören; Hug, Isabelle; Kaever, Volkhard; Abel zur Wiesch, Pia; Jenal, Urs

    2013-01-01

    Many bacteria mediate important life-style decisions by varying levels of the second messenger c-di-GMP. Behavioral transitions result from the coordination of complex cellular processes such as motility, surface adherence or the production of virulence factors and toxins. While the regulatory mechanisms responsible for these processes have been elucidated in some cases, the global pleiotropic effects of c-di-GMP are poorly understood, primarily because c-di-GMP networks are inherently complex in most bacteria. Moreover, the quantitative relationships between cellular c-di-GMP levels and c-di-GMP dependent phenotypes are largely unknown. Here, we dissect the c-di-GMP network of Caulobacter crescentus to establish a global and quantitative view of c-di-GMP dependent processes in this organism. A genetic approach that gradually reduced the number of diguanylate cyclases identified novel c-di-GMP dependent cellular processes and unraveled c-di-GMP as an essential component of C. crescentus cell polarity and its bimodal life cycle. By varying cellular c-di-GMP concentrations, we determined dose response curves for individual c-di-GMP-dependent processes. Relating these values to c-di-GMP levels modeled for single cells progressing through the cell cycle sets a quantitative frame for the successive activation of c-di-GMP dependent processes during the C. crescentus life cycle. By reconstructing a simplified c-di-GMP network in a strain devoid of c-di-GMP we defined the minimal requirements for the oscillation of c-di-GMP levels during the C. crescentus cell cycle. Finally, we show that although all c-di-GMP dependent cellular processes were qualitatively restored by artificially adjusting c-di-GMP levels with a heterologous diguanylate cyclase, much higher levels of the second messenger are required under these conditions as compared to the contribution of homologous c-di-GMP metabolizing enzymes. These experiments suggest that a common c-di-GMP pool cannot fully

  19. The Contemporary Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Houghton, R. A.

    2003-12-01

    C). Additions of greenhouse gases to the atmosphere from industrial activity, however, are increasing the concentrations of these gases, enhancing the greenhouse effect, and starting to warm the Earth.The rate and extent of the warming depend, in part, on the global carbon cycle. If the rate at which the oceans remove CO2 from the atmosphere were faster, e.g., concentrations of CO2 would have increased less over the last century. If the processes removing carbon from the atmosphere and storing it on land were to diminish, concentrations of CO2 would increase more rapidly than projected on the basis of recent history. The processes responsible for adding carbon to, and withdrawing it from, the atmosphere are not well enough understood to predict future levels of CO2 with great accuracy. These processes are a part of the global carbon cycle.Some of the processes that add carbon to the atmosphere or remove it, such as the combustion of fossil fuels and the establishment of tree plantations, are under direct human control. Others, such as the accumulation of carbon in the oceans or on land as a result of changes in global climate (i.e., feedbacks between the global carbon cycle and climate), are not under direct human control except through controlling rates of greenhouse gas emissions and, hence, climatic change. Because CO2 has been more important than all of the other greenhouse gases under human control, combined, and is expected to continue so in the future, understanding the global carbon cycle is a vital part of managing global climate.This chapter addresses, first, the reservoirs and natural flows of carbon on the earth. It then addresses the sources of carbon to the atmosphere from human uses of land and energy and the sinks of carbon on land and in the oceans that have kept the atmospheric accumulation of CO2 lower than it would otherwise have been. The chapter describes changes in the distribution of carbon among the atmosphere, oceans, and terrestrial ecosystems over

  20. Antiphase Light and Temperature Cycles Affect PHYTOCHROME B-Controlled Ethylene Sensitivity and Biosynthesis, Limiting Leaf Movement and Growth of Arabidopsis1[C][W

    PubMed Central

    Bours, Ralph; van Zanten, Martijn; Pierik, Ronald; Bouwmeester, Harro; van der Krol, Alexander

    2013-01-01

    In the natural environment, days are generally warmer than the night, resulting in a positive day/night temperature difference (+DIF). Plants have adapted to these conditions, and when exposed to antiphase light and temperature cycles (cold photoperiod/warm night [−DIF]), most species exhibit reduced elongation growth. To study the physiological mechanism of how light and temperature cycles affect plant growth, we used infrared imaging to dissect growth dynamics under +DIF and −DIF in the model plant Arabidopsis (Arabidopsis thaliana). We found that −DIF altered leaf growth patterns, decreasing the amplitude and delaying the phase of leaf movement. Ethylene application restored leaf growth in −DIF conditions, and constitutive ethylene signaling mutants maintain robust leaf movement amplitudes under −DIF, indicating that ethylene signaling becomes limiting under these conditions. In response to −DIF, the phase of ethylene emission advanced 2 h, but total ethylene emission was not reduced. However, expression analysis on members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase ethylene biosynthesis gene family showed that ACS2 activity is specifically suppressed in the petiole region under −DIF conditions. Indeed, petioles of plants under −DIF had reduced ACC content, and application of ACC to the petiole restored leaf growth patterns. Moreover, acs2 mutants displayed reduced leaf movement under +DIF, similar to wild-type plants under −DIF. In addition, we demonstrate that the photoreceptor PHYTOCHROME B restricts ethylene biosynthesis and constrains the −DIF-induced phase shift in rhythmic growth. Our findings provide a mechanistic insight into how fluctuating temperature cycles regulate plant growth. PMID:23979970

  1. Pomegranate Juice Metabolites, Ellagic Acid and Urolithin A, Synergistically Inhibit Androgen-Independent Prostate Cancer Cell Growth via Distinct Effects on Cell Cycle Control and Apoptosis

    PubMed Central

    Vicinanza, Roberto; Henning, Susanne M.; Heber, David

    2013-01-01

    Ellagitannins (ETs) from pomegranate juice (PJ) are bioactive polyphenols with chemopreventive potential against prostate cancer (PCa). ETs are not absorbed intact but are partially hydrolyzed in the gut to ellagic acid (EA). Colonic microflora can convert EA to urolithin A (UA), and EA and UA enter the circulation after PJ consumption. Here, we studied the effects of EA and UA on cell proliferation, cell cycle, and apoptosis in DU-145 and PC-3 androgen-independent PCa cells and whether combinations of EA and UA affected cell proliferation. EA demonstrated greater dose-dependent antiproliferative effects in both cell lines compared to UA. EA induced cell cycle arrest in S phase associated with decreased cyclin B1 and cyclin D1 levels. UA induced a G2/M arrest and increased cyclin B1 and cdc2 phosphorylation at tyrosine-15, suggesting inactivation of the cyclin B1/cdc2 kinase complex. EA induced apoptosis in both cell lines, while UA had a less pronounced proapoptotic effect only in DU-145. Cotreatment with low concentrations of EA and UA dramatically decreased cell proliferation, exhibiting synergism in PC-3 cells evaluated by isobolographic analysis and combination index. These data provide information on pomegranate metabolites for the prevention of PCa recurrence, supporting the role of gut flora-derived metabolites for cancer prevention. PMID:23710216

  2. An investigation and characterization on alginate hydogel dressing loaded with metronidazole prepared by combined inotropic gelation and freeze-thawing cycles for controlled release.

    PubMed

    Sarheed, Omar; Rasool, Bazigha K Abdul; Abu-Gharbieh, Eman; Aziz, Uday Sajad

    2015-06-01

    The purpose of this study was to investigate the effect of combined Ca(2+) cross-linking and freeze-thawing cycle method on metronidazole (model drug) drug release and prepare a wound film dressing with improved swelling property. The hydrogel films were prepared with sodium alginate (SA) using the freeze-thawing method alone or in combination with ionotropic gelation with CaCl2. The gel properties such as morphology, swelling, film thickness, and content uniformity and in vitro dissolution profiles using Franz diffusion cell were investigated. The cross-linking process was confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. In vitro protein adsorption test, in vivo wound-healing test, and histopathology were also performed. The hydrogel (F2) composed of 6% sodium alginate and 1% metronidazole prepared by combined Ca(2+) cross-linking and freeze-thawing cycles showed good swelling. This will help to provide moist environment at the wound site. With the in vivo wound-healing and histological studies, F2 was found to improve the wound-healing effect compared with the hydrogel without the drug, and the conventional product.

  3. Integrative Analysis of Circadian Transcriptome and Metabolic Network Reveals the Role of De Novo Purine Synthesis in Circadian Control of Cell Cycle

    PubMed Central

    Li, Ying; Li, Guang; Görling, Benjamin; Luy, Burkhard; Du, Jiulin; Yan, Jun

    2015-01-01

    Metabolism is the major output of the circadian clock in many organisms. We developed a computational method to integrate both circadian gene expression and metabolic network. Applying this method to zebrafish circadian transcriptome, we have identified large clusters of metabolic genes containing mostly genes in purine and pyrimidine metabolism in the metabolic network showing similar circadian phases. Our metabolomics analysis found that the level of inosine 5'-monophosphate (IMP), an intermediate metabolite in de novo purine synthesis, showed significant circadian oscillation in larval zebrafish. We focused on IMP dehydrogenase (impdh), a rate-limiting enzyme in de novo purine synthesis, with three circadian oscillating gene homologs: impdh1a, impdh1b and impdh2. Functional analysis revealed that impdh2 contributes to the daily rhythm of S phase in the cell cycle while impdh1a contributes to ocular development and pigment synthesis. The three zebrafish homologs of impdh are likely regulated by different circadian transcription factors. We propose that the circadian regulation of de novo purine synthesis that supplies crucial building blocks for DNA replication is an important mechanism conferring circadian rhythmicity on the cell cycle. Our method is widely applicable to study the impact of circadian transcriptome on metabolism in complex organisms. PMID:25714999

  4. RAE-1 ligands for the NKG2D receptor are regulated by E2F transcription factors, which control cell cycle entry

    PubMed Central

    Jung, Heiyoun; Hsiung, Benjamin; Pestal, Kathleen; Procyk, Emily

    2012-01-01

    The NKG2D stimulatory receptor expressed by natural killer cells and T cell subsets recognizes cell surface ligands that are induced on transformed and infected cells and facilitate immune rejection of tumor cells. We demonstrate that expression of retinoic acid early inducible gene 1 (RAE-1) family NKG2D ligands in cancer cell lines and proliferating normal cells is coupled directly to cell cycle regulation. Raet1 genes are directly transcriptionally activated by E2F family transcription factors, which play a central role in regulating cell cycle entry. Induction of RAE-1 occurred in primary cell cultures, embryonic brain cells in vivo, and cells in healing skin wounds and, accordingly, wound healing was delayed in mice lacking NKG2D. Transcriptional activation by E2Fs is likely coordinated with posttranscriptional regulation by other stress responses. These findings suggest that cellular proliferation, as occurs in cancer cells but also other pathological conditions, is a key signal tied to immune reactions mediated by NKG2D-bearing lymphocytes. PMID:23166357

  5. The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression

    PubMed Central

    Fukumura, Kazuhiro; Wakabayashi, Shunichi; Kataoka, Naoyuki; Sakamoto, Hiroshi; Suzuki, Yutaka; Nakai, Kenta; Mayeda, Akila; Inoue, Kunio

    2016-01-01

    The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon–exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT–PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH) to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes. PMID:27490541

  6. The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression.

    PubMed

    Fukumura, Kazuhiro; Wakabayashi, Shunichi; Kataoka, Naoyuki; Sakamoto, Hiroshi; Suzuki, Yutaka; Nakai, Kenta; Mayeda, Akila; Inoue, Kunio

    2016-01-01

    The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon-exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT-PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH) to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes. PMID:27490541

  7. Biogeochemical controls on Diel cycling of stable isotopes of dissolved O2 and dissolved inorganic carbon in the Big Hole River, Montana.

    PubMed

    Parker, Stephen R; Poulson, Simon R; Gammons, Christopher H; DeGrandpre, Michael D

    2005-09-15

    Rivers with high biological productivity typically show substantial increases in pH and dissolved oxygen (DO) concentration during the day and decreases at night, in response to changes in the relative rates of aquatic photosynthesis and respiration. These changes, coupled with temperature variations, may impart diel (24-h) fluctuations in the concentration of trace metals, nutrients, and other chemical species. A better understanding of diel processes in rivers is needed and will lead to improved methods of data collection for both monitoring and research purposes. Previous studies have used stable isotopes of dissolved oxygen (DO) and dissolved inorganic carbon (DIC) as tracers of geochemical and biological processes in streams, lakes, and marine systems. Although seasonal variation in 6180 of DO in rivers and lakes has been documented, no study has investigated diel changes in this parameter. Here, we demonstrate large (up to 13%o) cycles in delta18O-DO for two late summer sampling periods in the Big Hole River of southwest Montana and illustrate that these changes are correlated to variations in the DO concentration, the C-isotopic composition of DIC, and the primary productivity of the system. The magnitude of the diel cycle in delta18O-DO was greater in August versus September because of the longer photoperiod and warmer water temperatures. This study provides another biogeochemical tool for investigating the O2 and C budgets in rivers and may also be applicable to lake and groundwater systems.

  8. The centriole duplication cycle.

    PubMed

    Fırat-Karalar, Elif Nur; Stearns, Tim

    2014-09-01

    Centrosomes are the main microtubule-organizing centre of animal cells and are important for many critical cellular and developmental processes from cell polarization to cell division. At the core of the centrosome are centrioles, which recruit pericentriolar material to form the centrosome and act as basal bodies to nucleate formation of cilia and flagella. Defects in centriole structure, function and number are associated with a variety of human diseases, including cancer, brain diseases and ciliopathies. In this review, we discuss recent advances in our understanding of how new centrioles are assembled and how centriole number is controlled. We propose a general model for centriole duplication control in which cooperative binding of duplication factors defines a centriole 'origin of duplication' that initiates duplication, and passage through mitosis effects changes that license the centriole for a new round of duplication in the next cell cycle. We also focus on variations on the general theme in which many centrioles are created in a single cell cycle, including the specialized structures associated with these variations, the deuterosome in animal cells and the blepharoplast in lower plant cells.

  9. The centriole duplication cycle

    PubMed Central

    Fırat-Karalar, Elif Nur; Stearns, Tim

    2014-01-01

    Centrosomes are the main microtubule-organizing centre of animal cells and are important for many critical cellular and developmental processes from cell polarization to cell division. At the core of the centrosome are centrioles, which recruit pericentriolar material to form the centrosome and act as basal bodies to nucleate formation of cilia and flagella. Defects in centriole structure, function and number are associated with a variety of human diseases, including cancer, brain diseases and ciliopathies. In this review, we discuss recent advances in our understanding of how new centrioles are assembled and how centriole number is controlled. We propose a general model for centriole duplication control in which cooperative binding of duplication factors defines a centriole ‘origin of duplication’ that initiates duplication, and passage through mitosis effects changes that license the centriole for a new round of duplication in the next cell cycle. We also focus on variations on the general theme in which many centrioles are created in a single cell cycle, including the specialized structures associated with these variations, the deuterosome in animal cells and the blepharoplast in lower plant cells. PMID:25047614

  10. The negative interplay between Aurora A/B and BRCA1/2 controls cancer cell growth and tumorigenesis via distinct regulation of cell cycle progression, cytokinesis, and tetraploidy

    PubMed Central

    2014-01-01

    It is well known that the activation of Aurora A/B (Aur A/B) or inactivation of BRCA1/2 induces tumor formation. Others and we have reported that the mutual suppression between Aur A/B and BRCA1/2 may manipulate cancer cell growth and tumorigenesis, however, the interactive regulation and mechanism between these molecules are still elusive. In this study, by consecutive silencing of Aur A/B or/and BRCA1/2 with specific shRNAs, we showed that, in BRCA2-deficient pancreatic cancer cell line Capan-1 and in ovarian cancer cell line OVCA433, Aur A/B and BRCA1/2 inversely regulated the expression of each other likely through proteasome-mediated proteolysis but not through gene transcription. Aur A/B and BRCA1/2 conversely regulated cell cycle progression mainly through control of p53 and cyclin A. Moreover, the disruption of Aur A/B blocked abnormal cytokinesis and decreased cell multinuclearity and chromosome tetraploidy, whereas the deprivation of BRCA1/2 promoted the abnormal cytokinesis and enhanced the cell multinuclearity and tetraploidy. Furthermore, we showed by animal assays that the depletion of Aur A/B inhibited tumor growth of both cell lines, while the knockdown of BRCA1/2 promoted the tumor growth. However, the concurrent silencing of Aur A/B and BRCA1/2 diminished the effects of these molecules on the regulation of cell cycle, cytokinesis, and tetraploidy, leading to the burdened tumor sizes similar to those induced by scrambled shRNA-treated control cells. In summary, our study revealed that the negative interplay between Aur A/B and BRCA1/2 inversely controls the cell proliferation, cell cycle progression, cell multinuclearity, and tetraploidization to modulate tumorigenesis. PMID:24775809

  11. Aggregation of Ribosomal Protein S6 at Nucleolus Is Cell Cycle-Controlled and Its Function in Pre-rRNA Processing Is Phosphorylation Dependent.

    PubMed

    Zhang, Duo; Chen, Hui-Peng; Duan, Hai-Feng; Gao, Li-Hua; Shao, Yong; Chen, Ke-Yan; Wang, You-Liang; Lan, Feng-Hua; Hu, Xian-Wen

    2016-07-01

    Ribosomal protein S6 (rpS6) has long been regarded as one of the primary r-proteins that functions in the early stage of 40S subunit assembly, but its actual role is still obscure. The correct forming of 18S rRNA is a key step in the nuclear synthesis of 40S subunit. In this study, we demonstrate that rpS6 participates in the processing of 30S pre-rRNA to 18S rRNA only when its C-terminal five serines are phosphorylated, however, the process of entering the nucleus and then targeting the nucleolus does not dependent its phosphorylation. Remarkably, we also find that the aggregation of rpS6