Science.gov

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 Alan; Rochau, Gary Eugene; 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. Cell cycle control in Alphaproteobacteria.

    PubMed

    Collier, Justine

    2016-04-01

    Alphaproteobacteria include many medically and environmentally important organisms. Despite the diversity of their niches and lifestyles, from free-living to host-associated, they usually rely on very similar mechanisms to control their cell cycles. Studies on Caulobacter crescentus still lay the foundation for understanding the molecular details of pathways regulating DNA replication and cell division and coordinating these two processes with other events of the cell cycle. This review highlights recent discoveries on the regulation and the mode of action of conserved global regulators and small molecules like c-di-GMP and (p)ppGpp, which play key roles in cell cycle control. It also describes several newly identified mechanisms that modulate cell cycle progression in response to stresses or environmental conditions. PMID:26871482

  4. Myc and cell cycle control.

    PubMed

    Bretones, Gabriel; Delgado, M Dolores; León, Javier

    2015-05-01

    Soon after the discovery of the Myc gene (c-Myc), it became clear that Myc expression levels tightly correlate to cell proliferation. The entry in cell cycle of quiescent cells upon Myc enforced expression has been described in many models. Also, the downregulation or inactivation of Myc results in the impairment of cell cycle progression. Given the frequent deregulation of Myc oncogene in human cancer it is important to dissect out the mechanisms underlying the role of Myc on cell cycle control. Several parallel mechanisms account for Myc-mediated stimulation of the cell cycle. First, most of the critical positive cell cycle regulators are encoded by genes induced by Myc. These Myc target genes include Cdks, cyclins and E2F transcription factors. Apart from its direct effects on the transcription, Myc is able to hyperactivate cyclin/Cdk complexes through the induction of Cdk activating kinase (CAK) and Cdc25 phosphatases. Moreover, Myc antagonizes the activity of cell cycle inhibitors as p21 and p27 through different mechanisms. Thus, Myc is able to block p21 transcription or to induce Skp2, a protein involved in p27 degradation. Finally, Myc induces DNA replication by binding to replication origins and by upregulating genes encoding proteins required for replication initiation. Myc also regulates genes involved in the mitotic control. A promising approach to treat tumors with deregulated Myc is the synthetic lethality based on the inhibition of Cdks. Thus, the knowledge of the Myc-dependent cell cycle regulatory mechanisms will help to discover new therapeutic approaches directed against malignancies with deregulated Myc. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology. PMID:24704206

  5. 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.

  6. 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

  7. 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.

  8. Technology Assessment Report: Duty Cycling Controllers Revisited

    SciTech Connect

    Webster, Tom; Benenson, Peter

    1998-05-01

    This report covers an assessment of two brands of energy management controllers that are currently being offered that utilize the principle of duty cycling to purportedly save energy for unitary air conditioners and heat pumps, gas furnaces, and gas fired boilers. The results of an extensive review of past research on this subject as well as a review of vendor sponsored field testing of these controllers compares these newer controllers to those of the past. Included also is a discussion of how the duty cycling principle is prone to misinterpretation as to its potential to save energy.

  9. 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…

  10. 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.

  11. 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

  12. 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

  13. 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.

  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. One-Cycle Controlled Single Phase UPS Inverter

    NASA Astrophysics Data System (ADS)

    Xiangli, Li; Hanhong, Qi

    A one-cycle controlled single-phase full-bridge DC-AC inverter is proposed. One-cycle control is a nonlinear control method which has fast transient response and good tracking performance. The one-cycle control immunizes the inverter against the perturbation of input dc bus and provides well system dynamic regulation with hybrid sinusoidal PWM control. The basic operational theory and control method are discussed in this paper. Finally, simulation waveforms and experimental results are given. The simulation and experimental results demonstrate the effectiveness of this control technique for inverters in UPS applications, especially when nonlinear loads must to be supplied and line has large undesirable harmonic components.

  16. Microbial control over carbon cycling in soil

    PubMed Central

    Schimel, Joshua P.; Schaeffer, Sean M.

    2012-01-01

    A major thrust of terrestrial microbial ecology is focused on understanding when and how the composition of the microbial community affects the functioning of biogeochemical processes at the ecosystem scale (meters-to-kilometers and days-to-years). While research has demonstrated these linkages for physiologically and phylogenetically “narrow” processes such as trace gas emissions and nitrification, there is less conclusive evidence that microbial community composition influences the “broad” processes of decomposition and organic matter (OM) turnover in soil. In this paper, we consider how soil microbial community structure influences C cycling. We consider the phylogenetic level at which microbes form meaningful guilds, based on overall life history strategies, and suggest that these are associated with deep evolutionary divergences, while much of the species-level diversity probably reflects functional redundancy. We then consider under what conditions it is possible for differences among microbes to affect process dynamics, and argue that while microbial community structure may be important in the rate of OM breakdown in the rhizosphere and in detritus, it is likely not important in the mineral soil. In mineral soil, physical access to occluded or sorbed substrates is the rate-limiting process. Microbial community influences on OM turnover in mineral soils are based on how organisms allocate the C they take up – not only do the fates of the molecules differ, but they can affect the soil system differently as well. For example, extracellular enzymes and extracellular polysaccharides can be key controls on soil structure and function. How microbes allocate C may also be particularly important for understanding the long-term fate of C in soil – is it sequestered or not? PMID:23055998

  17. Cell cycle control and seed development

    PubMed Central

    Dante, Ricardo A.; Larkins, Brian A.; Sabelli, Paolo A.

    2014-01-01

    Seed development is a complex process that requires coordinated integration of many genetic, metabolic, and physiological pathways and environmental cues. Different cell cycle types, such as asymmetric cell division, acytokinetic mitosis, mitotic cell division, and endoreduplication, frequently occur in sequential yet overlapping manner during the development of the embryo and the endosperm, seed structures that are both products of double fertilization. Asymmetric cell divisions in the embryo generate polarized daughter cells with different cell fates. While nuclear and cell division cycles play a key role in determining final seed cell numbers, endoreduplication is often associated with processes such as cell enlargement and accumulation of storage metabolites that underlie cell differentiation and growth of the different seed compartments. This review focuses on recent advances in our understanding of different cell cycle mechanisms operating during seed development and their impact on the growth, development, and function of seed tissues. Particularly, the roles of core cell cycle regulators, such as cyclin-dependent-kinases and their inhibitors, the Retinoblastoma-Related/E2F pathway and the proteasome-ubiquitin system, are discussed in the contexts of different cell cycle types that characterize seed development. The contributions of nuclear and cellular proliferative cycles and endoreduplication to cereal endosperm development are also discussed. PMID:25295050

  18. Biological Controls on the Hydrologic Cycle

    NASA Astrophysics Data System (ADS)

    Berry, J. A.

    2009-05-01

    Unlike most other parts of hydrologic cycle, that part involving plants is strongly influenced by behaviors that fall outside the realm of simple physics, and are, therefore, difficult to model. Plants have the capacity to make "decisions" that profoundly affect the surface energy budget, boundary layer processes and atmospheric dynamics over the continents. These decisions of plants are apparently based on anatomical structures and physiological mechanisms that have been tuned by evolutionary processes to permit plants to address the central dilemma of their existence. To grow requires that they open their stomata to allow CO2 to diffuse into their leaves, but they must also permit water to escape to the dry atmosphere. This water must be used sparingly lest they exhaust soil water and die of dessication, but to forgo using it comes at the expense of growth and competitive advantage. Improvements in our understanding of the physiological and environmental constraints that frame this dilemma have led to improvements in our ability to predict and model the responses of plants in the hydrologic cycle. However, there is, yet, much room for improvement in our understanding of plant hydrology and how to measure and model it. I will touch on new insights into mechanisms that regulate stomatal conductance, applications of stable isotopes for calibrating conductance parameterizations and a new tracer for assessing conductance at regional scales.

  19. Experimental implementation of automatic 'cycle to cycle' control of a chiral simulated moving bed separation.

    PubMed

    Amanullah, Mohammad; Grossmann, Cristian; Mazzotti, Marco; Morari, Manfred; Morbidelli, Massimo

    2007-09-21

    In the absence of a suitable controller, currently simulated moving beds (SMBs) are operated suboptimally to cope with system uncertainties and to guarantee robustness of operation. Recently, we have developed a 'cycle to cycle' optimizing controller that not only makes use of minimal system information, i.e. only the Henry constants and average bed voidage, but also optimizes the process performance and taps the full economic potential of the SMB technology. The experimental implementation of the 'cycle to cycle' optimizing controller had been carried out for achiral separation. For chiral separation however, application of any online controller has not been possible because an appropriate online monitoring system has not been available. This work reports and discusses the first experimental implementation of the 'cycle to cycle' optimizing control for chiral separations. A mixture of guaifenesin enantiomers is separated on Chiralcel OD columns with ethanol as mobile phase in a eight-column four sections laboratory SMB unit. The results show that the controller, although using minimal information about the retention of the two enantiomers, is able to meet product and process specifications, can optimize the process performance, and is capable of rejecting disturbances that may occur during the operation of the SMB plant. PMID:17707852

  20. Bypass control valve seal and bearing life cycle test report

    NASA Technical Reports Server (NTRS)

    Lundback, A. V.

    1972-01-01

    The operating characteristics of a bypass control valve seal and bearing life cycle tests are reported. Data from the initial assembly, leak, torque, and deflection tests are included along with the cycle life test results and conclusions. The equipment involved was to be used in the nuclear engine for the rocket vehicles program.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. 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

  6. 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.

  7. Cell cycle control of polyomavirus-induced transformation.

    PubMed Central

    Chen, H H; Fluck, M M

    1993-01-01

    The cell cycle dependence of polyomavirus transformation was analyzed in infections of nonpermissive Fischer rat (FR3T3) cells released from G0. A 5- to 100-fold (average, ca. 20-fold) difference in relative frequency of transformation was found for cells infected in the early G1 phase of the cell cycle compared with cells infected in G2. Differences in the relative level of early viral gene expression in those two cell populations were equivalent to those obtained for transformation frequencies. The difference in transformation potential was accounted for only in part by a cell cycle control of viral adsorption (2- to 15-fold effect). Furthermore, in cells infected in the early G1 phase, viral gene expression was induced as a big synchronous burst of large transcripts of variable sizes, delayed till the G1 phase of the cell cycle after that in which infection took place. Thus, the results demonstrate that the abortive infection cycle of G0-released FR3T3 cells is cell cycle regulated at least at two steps: adsorption and another early step, nuclear transport, decapsidation, up to or including the transcription of the viral early genes. The cell cycle regulation of these steps results in a similar regulation of the abortive and stable transformation processes, although it is more pronounced for the latter. A model implicating c-fos and c-jun is proposed. Images PMID:8383223

  8. 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.

  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. Does Arabidopsis thaliana DREAM of cell cycle control?

    PubMed

    Fischer, Martin; DeCaprio, James A

    2015-08-01

    Strict temporal control of cell cycle gene expression is essential for all eukaryotes including animals and plants. DREAM complexes have been identified in worm, fly, and mammals, linking several distinct transcription factors to coordinate gene expression throughout the cell cycle. In this issue of The EMBO Journal, Kobayashi et al (2015) identify distinct activator and repressor complexes for genes expressed during the G2 and M phases in Arabidopsis that can be temporarily separated during proliferating and post‐mitotic stages of development. The complexes incorporate specific activator and repressor MYB and E2F transcription factors and indicate the possibility of the existence of multiple DREAM complexes in plants. PMID:26089020

  12. 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.

  13. 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).

  14. 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.

  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. Price controls for medical innovations in a life cycle perspective.

    PubMed

    Sorek, Gilad

    2014-01-01

    We study the market for new medical technologies from a life cycle perspective, incorporating the fact that healthcare utilization is biased towards old age. Contrary to conventional wisdom, we find that price controls on medical innovations can expand investment in medical R&D and results in Pareto superior social outcomes, a consequence of the price controls' ability to increase saving. Importantly, this finding occurs only when the price cap regime is extensive: selective regulation on few technologies - such as pharmaceuticals alone - have the conventional negative effect on innovation. PMID:23339083

  17. Emerging regulatory mechanisms in ubiquitin-dependent cell cycle control

    PubMed Central

    Mocciaro, Annamaria; Rape, Michael

    2012-01-01

    The covalent modification of proteins with ubiquitin is required for accurate cell division in all eukaryotes. Ubiquitylation depends on an enzymatic cascade, in which E3 enzymes recruit specific substrates for modification. Among ~600 human E3s, the SCF (Skp1–cullin1–F-box) and the APC/C (anaphase-promoting complex/cyclosome) are known for driving the degradation of cell cycle regulators to accomplish irreversible cell cycle transitions. The cell cycle machinery reciprocally regulates the SCF and APC/C through various mechanisms, including the modification of these E3s or the binding of specific inhibitors. Recent studies have provided new insight into the intricate relationship between ubiquitylation and the cell division apparatus as they revealed roles for atypical ubiquitin chains, new mechanisms of substrate and E3 regulation, as well as extensive crosstalk between ubiquitylation enzymes. Here, we review these emerging regulatory mechanisms of ubiquitin-dependent cell cycle control and discuss how their manipulation might provide therapeutic benefits in the future. PMID:22357967

  18. 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

  19. 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.

  20. 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

  1. Does Arabidopsis thaliana DREAM of cell cycle control?

    PubMed Central

    Fischer, Martin; DeCaprio, James A

    2015-01-01

    Strict temporal control of cell cycle gene expression is essential for all eukaryotes including animals and plants. DREAM complexes have been identified in worm, fly, and mammals, linking several distinct transcription factors to coordinate gene expression throughout the cell cycle. In this issue of The EMBO Journal, Kobayashi et al (2015) identify distinct activator and repressor complexes for genes expressed during the G2 and M phases in Arabidopsis that can be temporarily separated during proliferating and post-mitotic stages of development. The complexes incorporate specific activator and repressor MYB and E2F transcription factors and indicate the possibility of the existence of multiple DREAM complexes in plants. PMID:26089020

  2. 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. PMID:26970388

  3. Parametric Investigation of Brayton Cycle for High Temperature Gas-Cooled Reactor

    SciTech Connect

    Chang Oh

    2004-07-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is investigating a Brayton cycle efficiency improvement on a high temperature gas-cooled reactor (HTGR) as part of Generation-IV nuclear engineering research initiative. In this project, we are investigating helium Brayton cycles for the secondary side of an indirect energy conversion system. Ultimately we will investigate the improvement of the Brayton cycle using other fluids, such as supercritical carbon dioxide. Prior to the cycle improvement study, we established a number of baseline cases for the helium indirect Brayton cycle. These cases look at both single-shaft and multiple-shaft turbomachinary. The baseline cases are based on a 250 MW thermal pebble bed HTGR. The results from this study are applicable to other reactor concepts such as a very high temperature gas-cooled reactor (VHTR), fast gas-cooled reactor (FGR), supercritical water reactor (SWR), and others. In this study, we are using the HYSYS computer code for optimization of the helium Brayton cycle. Besides the HYSYS process optimization, we performed parametric study to see the effect of important parameters on the cycle efficiency. For these parametric calculations, we use a cycle efficiency model that was developed based on the Visual Basic computer language. As a part of this study we are currently investigated single-shaft vs. multiple shaft arrangement for cycle efficiency and comparison, which will be published in the next paper.The ultimate goal of this study is to use supercritical carbon dioxide for the HTGR power conversion loop in order to improve the cycle efficiency to values great than that of the helium Brayton cycle. This paper includes preliminary calculations of the steady state overall Brayton cycle efficiency based on the pebble bed reactor reference design (helium used as the working fluid) and compares those results with an initial calculation of a CO2 Brayton cycle.

  4. Integrative analysis of cell cycle control in budding yeast.

    PubMed

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

    2004-08-01

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

    Energy Science and Technology Software Center (ESTSC)

    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.

  6. 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.

  7. 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.

  8. 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. PMID:26654117

  9. 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

  10. 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

  11. 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. PMID:26372954

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. Apicomplexan cell cycle flexibility: centrosome controls the clutch

    PubMed Central

    Chen, Chun-Ti; Gubbels, Marc-Jan

    2015-01-01

    The centrosome serves as a central hub coordinating multiple cellular events in eukaryotes. A recent study in Toxoplasma gondii revealed a unique bipartite structure of the centrosome, which coordinates the nuclear cycle (S-phase and mitosis) and budding cycle (cytokinesis) of the parasite, and deciphers the principle behind flexible apicomplexan cell division modes. PMID:25899747

  18. 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

  19. Basal p21 controls population heterogeneity in cycling and quiescent cell cycle states

    PubMed Central

    Overton, K. Wesley; Spencer, Sabrina L.; Noderer, William L.; Meyer, Tobias; Wang, Clifford L.

    2014-01-01

    Phenotypic heterogeneity within a population of genetically identical cells is emerging as a common theme in multiple biological systems, including human cell biology and cancer. Using live-cell imaging, flow cytometry, and kinetic modeling, we showed that two states—quiescence and cell cycling—can coexist within an isogenic population of human cells and resulted from low basal expression levels of p21, a Cyclin-dependent kinase (CDK) inhibitor (CKI). We attribute the p21-dependent heterogeneity in cell cycle activity to double-negative feedback regulation involving CDK2, p21, and E3 ubiquitin ligases. In support of this mechanism, analysis of cells at a point before cell cycle entry (i.e., before the G1/S transition) revealed a p21–CDK2 axis that determines quiescent and cycling cell states. Our findings suggest a mechanistic role for p21 in generating heterogeneity in both normal tissues and tumors. PMID:25267623

  20. 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

  1. 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.

  2. 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…

  3. Hair cycle control by leptin as a new anagen inducer.

    PubMed

    Sumikawa, Yasuyuki; Inui, Shigeki; Nakajima, Takeshi; Itami, Satoshi

    2014-01-01

    Our purpose is to clarify the physiological role of leptin in hair cycle as leptin reportedly causes activation of Stat3, which is indispensable for hair cycling. While hair follicles in dorsal skin of 5-week-old C57/BL6 mice had progressed to late anagen phase, those in dorsal skin of 5-week-old leptin receptor deficient db/db mice remained in the first telogen and later entered the anagen at postnatal day 40, indicating that deficiency in leptin receptor signalling delayed the second hair cycle progression. Next, we shaved dorsal hairs on wild-type mice at postnatal 7 weeks and injected skin with mouse leptin or a mock. After 20 days, although mock injection showed no effect, hair growth occurred around leptin injection area. Human leptin fragment (aa22-56) had similar effects. Although the hair cycle of ob/ob mice was similar to that of wild-type mice, injection of mouse leptin on ob/ob mice at postnatal 7 weeks induced anagen transition. Immunohistochemically, leptin is expressed in hair follicles from catagen to early anagen in wild-type mice, suggesting that leptin is an anagen inducer in vivo. Phosphorylation of Erk, Jak2 and Stat3 in human keratinocytes was stimulated by leptin and leptin fragment. In addition, RT-PCR and ELISA showed that the production of leptin by human dermal papilla cells increased under hypoxic condition, suggesting that hypoxia in catagen/telogen phase promotes leptin production, preparing for entry into the next anagen. In conclusion, leptin, a well-known adipokine, acts as an anagen inducer and represents a new player in hair biology. PMID:24237265

  4. 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

  5. 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.

  6. What Controls the Pacing of 100-ky Glacial Cycles?

    NASA Astrophysics Data System (ADS)

    Raymo, M. E.; Kawamura, K.; Lisiecki, L.; Thompson, W. G.; Severinghaus, J. P.

    2006-12-01

    Climate variations over the last ~700,000 years are characterized by orbital periodicities of 100, 41 and 23 ky. While 23- and 41-ky components are understood as linear climatic responses to forcing by precession (modulated by eccentricity) and obliquity, respectively, the 100-ky cycle cannot be explained as a linear response to eccentricity. Rather, it has been suggested that the 100-ky cycle is caused by skipping of higher frequency beats which results in the bundling of either 4 or 5 precession cycles (Raymo, Paleoceanography, 1997), or 2 or 3 obliquity cycles (Huybers and Wunsch, Nature, 2005), each grouping resulting in an average 100 ky periodicity. However, verification of these competing hypotheses has not been possible because of the lack of accurately dated climate proxies. Here, using statistical tests of newly established chronologies of Antarctic climate (Kawamura et al., AGU 2006 fall meeting) and sea level high stands (Thompson, in preparation), we show that precession pacing is statistically more significant than obliquity pacing for the last five glacial terminations. We used the timings of Antarctic warmings at terminations from the Dome Fuji ice core for termination I to III, and from the Vostok core for termination IV. The timing of termination V was estimated by shifting the Dome C (EDC2) timescale to match the timing of peak MIS 11.3 with the Vostok record. The time of onset for the sea level high stands of the last four interglacial periods were estimated by correcting radiometric fossil coral ages with open-system age equations (Thompson et al., 2003, EPSL). Our results show that the null hypothesis for precession pacing can be rejected at the 3% significance level for the last five terminations from ice cores and for four terminations from sea level high stands, whereas the null hypothesis for obliquity pacing can be rejected only at >10% significance level. The statistical power of test for obliquity is high (>95% at the 10% significance

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Burn to cycle: energetics of cell-cycle control and stem cell maintenance.

    PubMed

    Mans, Laurie D; Haramis, Anna-Pavlina G

    2014-01-01

    Stem cells have the unique ability to both maintain the stem cell population via self-renewal and give rise to differentiated cells. The balance between these options is very delicate and important for the short- and long-term maintenance of tissue homeostasis in an organism. Pathways involved in integrating environmental cues and in directing energy metabolism play an important role in the fate decisions of stem cells. In this review, we give an overview of the effects of cellular and systemic metabolic states on stem-cell fate in both embryonic and in adult stem cell populations, with a particular emphasis on cell-cycle regulation. We discuss the major pathways implicated in sensing energetic status and regulating metabolism, including: the mTOR pathway, Forkhead-box-O transcription factors (FoxOs), Sirtuins, reactive oxygen species (ROS), AMP-activated kinase (AMPK) and LKB1, the mTOR pathway and hypoxia inducible factors (HIFs). Given the importance of a correct balance between self-renewal and differentiation, understanding the mechanisms that drive stem-cell fate in different metabolic conditions will provide more insight in stem cell biology in both health and disease. PMID:24896332

  14. 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

  15. 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

  16. 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

  17. 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.

  18. The biological control on Si cycling in the Okavango Delta

    NASA Astrophysics Data System (ADS)

    Struyf, Eric; Mosimane, Keotshepile; Van Pelt, Dimitri; Murray-Hudson, Mike; Meire, Patrick; Frings, Patrick; Schoelynck, Jonas; Gondwé, Mangaliso; Wolski, Piotr; Conley, Daniel

    2015-04-01

    We assessed the role of vegetation and hydrology in the Si cycle in the Okavango Delta (Botswana). Our results show a large storage of biogenic Si (BSi) in vegetation and the sediments. The biological storage is among the highest observed so far for any ecosystem worldwide. Floodplain vegetation accumulates similar amounts of BSi in both the temporary floodplains and the permanent floodplains, with most values observed between 20-100 g Si m-2. This vegetation Si, after litterfall, contributes to a large biogenic Si storage in the sediments. In temporary floodplains, sediments contain less BSi (375 -1950 g Si m-2 in the top 5 cm) than in the permanent floodplains (1950 - 3600 g Si m-2 in the top 5 cm). BSi concentrations in the floodplain sediments decline exponentially indicating rapid dissolution. In the occasional and seasonal floodplains, unidirectional solute transfer from floodplains to tree covered islands removes Si from the riverine systems. The hydrology of many tropical wetlands is undergoing major changes due to human alteration of river morphology and watersheds. Model predictions also project substantial future changes in hydrology and climate . This will have implications for flooding extent and seasonality, factors that may induce changes in Si storage in the Okavango Delta. Recently, annual BSi uptake in global vegetation was estimated at about 85 Tmole. Of this, the total surface of wetlands worldwide contributes approximately 4.16 Tmole a-1. Our conservative vegetation BSi production estimate of 0.02 Tmole of Si a-1 would represent about 0.4% of total annual uptake in wetland vegetation worldwide within the Okavango Delta alone, despite it covering only about 0.1% of global wetland area. Tropical rivers deliver about 70-80% of the global Si load into the ocean , implying it is crucial to assess environmental factors that can influence its transport. Our data and the limited available literature data available clearly show that wetlands and

  19. 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

  20. Control on frequency hierarchy in sequences of meter-scale carbonate cycles

    SciTech Connect

    Drummond, C.N.; Wilkinson, B.H. . Dept. of Geological Sciences)

    1992-01-01

    Proponents of allocyclic (eustatic) control of meter-scale carbonate cycle formation commonly point to the presence of an hierarchy of cycle thickness as compelling evidence for a Milankovitch origin of high-frequency sea-level change during cycle deposition. When assuming constant subsidence and sedimentation rate, thickness is directly related to duration of eustatic sea-level change (the Fischer plot assumption), and ratios of individual cycle period to megacycle period are then found to be similar to ratios of Milankovitch orbital variations, typically four or five to one. However, a variety of computational models of carbonate cycle formation indicate that a single period of eustatic sea-level change will give rise to multiple shallowing upward sequences when depth-dependent parameters of sediment generation are also included. When employing constant sedimentation and subsidence rates, as well as a depth-controlled flooding lag time for the initiation of sediment accumulation, patterns of cycle hierarchy are seen to vary both with amplitude of sea-level change and with subsidence rate. Low sea-level amplitudes and intermediate subsidence rates give rise to the most complex stacking patterns. Because patterns of cycle hierarchy are very sensitive to inferred rates of subsidence, the number of cycles produced during any single sea-level rise will depend upon lateral position of a sequence along any shelf undergoing differential subsidence. Hence, the presence of cycle-megacycle thickness/period ratios either within or outside the Milankovitch range makes no comment on the role of multiple forcing functions. As such, the presence of a frequency hierarchy in cyclic carbonate sequences can not be used to argue for an orbitally forced origin of upward-shallowing carbonate cycles.

  1. 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

  2. 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.

  3. 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.

  4. 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

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

    DOEpatents

    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.

  6. 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.

  7. Limit cycle analysis of active disturbance rejection control system with two nonlinearities.

    PubMed

    Wu, Dan; Chen, Ken

    2014-07-01

    Introduction of nonlinearities to active disturbance rejection control algorithm might have high control efficiency in some situations, but makes the systems with complex nonlinearity. Limit cycle is a typical phenomenon that can be observed in the nonlinear systems, usually causing failure or danger of the systems. This paper approaches the problem of the existence of limit cycles of a second-order fast tool servo system using active disturbance rejection control algorithm with two fal nonlinearities. A frequency domain approach is presented by using describing function technique and transfer function representation to characterize the nonlinear system. The derivations of the describing functions for fal nonlinearities and treatment of two nonlinearities connected in series are given to facilitate the limit cycles analysis. The effects of the parameters of both the nonlinearity and the controller on the limit cycles are presented, indicating that the limit cycles caused by the nonlinearities can be easily suppressed if the parameters are chosen carefully. Simulations in the time domain are performed to assess the prediction accuracy based on the describing function. PMID:24795034

  8. 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.

  9. Entrained gasification combined-cycle control study. Volume 3: model descriptions. Final report

    SciTech Connect

    Clark, J.; Denton, L.; Hashemi, M.; Joiner, J.; Smelser, S.; Chowaniec, C.; Hobbs, M.; Jennings, S.; Phelts, E.

    1980-07-01

    Two control strategies were evaluated for a new type of electric power plant as part of a large utility network. An entrained coal gasifier fuels a gas turbine/steam turbine combined-cycle unit forming the integrated plant which was simulated by computer to analyze alternative control strategies. Transient operation of this gasification-combined-cycle (GCC) plant was studied to determine open-loop response as a stand-alone plant, as well as closed-loop response while functioning in a typical utility power system. GCC plant performance during specified operating contingencies, such as equipment trip or emergency shutdown, was also studied. This volume presents the model descriptions for the Texaco entrained gasifiers, Selexol unit, oxygen plant, scrubber, ammonia absorber, water balance, combustion turbine-generator and gas-turbine controls, heat recovery steam generators, steam turbine-generator and steam-turbine controls, fuel gas expander, power system, and station controller.

  10. 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

  11. 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

  12. 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

  13. 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

    2013-01-01

    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. PMID:23592841

  14. Cell cycle control in isoproterenol-induced murine salivary acinar cell proliferation.

    PubMed

    Zeng, T; Yamamoto, H; Bowen, E; Broverman, R L; Nguyen, K H; Humphreys-Beher, M G

    1996-11-01

    The eukaryotic cell cycle is a summary of a complex network of signal transduction pathways resulting in both DNA replication and cell division. Cyclin-dependent kinases (CDKs) control the cell cycle in all eukaryotes, whereas other proteins, known as cyclins, act as their regulatory subunits. Chronic injection with isoproterenol (ISO) can induce acinar cell proliferation in rodent salivary glands. Cyclins and CDK proteins from control and ISO-treated murine parotid acinar cells were detected by using Western blotting techniques. By comparing the expression of these cell cycle regulatory kinases in the parotid acinar cell transition from a quiescent state to a hypertrophic state, we found rapid increases in the protein levels of all CDKs, cyclin D and proliferating cell nuclear antigen (PCNA). The highest protein levels for CDKs and cyclins appeared at about 72 hr of ISO stimulation and were coincident with the highest rate of increase in gland wet weight. After 72 hr, the increase of both cell cycle protein and gland wet weight began to subside. By using a co-immunoprecipitation method, the following cell cycle regulators (CDK-cyclin complexes) were detected, CDK4-cyclin D, CDK2-cyclin E, CDK2-cyclin A, and cdc2-cyclin B, along with an increase in kinase activity over control untreated animals. Additionally, we detected significant decreases in the newly isolated CDK inhibitor (CKI) p27kip but not Wee 1 kinase. The increased levels of CKI correlated with a decrease in kinase activity of CDK/cyclin complexes by 144 hr of chronic isoproterenol treatment. Our data suggest that the holoenzymes for cell cycle control (cyclin-CDK complexes) function as a final regulatory mechanism leading to salivary gland acinar cell proliferation. The gradual decline in protein levels of the CDKs and cyclins after 3 days of chronic treatment further indicates that ISO-induced proliferation of parotid acinar cells is self-limiting and non-tumorigenic. PMID:9375366

  15. 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...

  16. 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...

  17. 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)

  18. SON Controls Cell Cycle Progression by Coordinated Regulation of RNA Splicing

    PubMed Central

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

    2011-01-01

    SUMMARY 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 co-factor contributing to efficient splicing of cell cycle regulators. Down-regulation 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 co-transcriptional 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. PMID:21504830

  19. Robustness of cell cycle control and flexible orders of signaling events

    PubMed Central

    Zhu, Hao; Mao, Yanlan

    2015-01-01

    The highly robust control of cell cycles in eukaryotes enables cells to undergo strictly ordered G1/S/G2/M phases and respond adaptively to regulatory signals; however the nature of the robustness remains obscure. Specifically, it is unclear whether events of signaling should be strictly ordered and whether some events are more robust than others. To quantitatively address the two questions, we have developed a novel cell cycle model upon experimental observations. It contains positive and negative E2F proteins and two Cdk inhibitors, and is parameterized, for the first time, to generate not only oscillating protein concentrations but also periodic signaling events. Events and their orders reconstructed under varied conditions indicate that proteolysis of cyclins and Cdk complexes by APC and Skp2 occurs highly robustly in a strict order, but many other events are either dispensable or can occur in flexible orders. These results suggest that strictly ordered proteolytic events are essential for irreversible cell cycle progression and the robustness of cell cycles copes with flexible orders of signaling events, and unveil a new and important dimension to the robustness of cell cycle control in particular and to biological signaling in general. PMID:26419873

  20. 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

  1. 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

  2. Higher-order sliding mode control of leg power in paraplegic FES-cycling.

    PubMed

    Farhoud, Aidin; Erfanian, Abbas

    2010-01-01

    In this paper, we propose a robust control methodology based on high order sliding mode (HOSM) for control of the leg power in FES-Cycling. A major obstacle to the development of control systems for functional electrical stimulation (FES) has been the highly non-linear, time-varying properties of neuromusculoskeletal systems. A useful and powerful control scheme to deal with the uncertainties, nonlinearities, and bounded external disturbances is the sliding mode control (SMC). The main drawback of the classical sliding mode is mostly related to the so-called chattering which is dangerous for FES applications. To avoid chattering, HOSM approaches were proposed. Keeping the main advantages of the original approach, at the same time they totally remove the chattering effect and provide for even higher accuracy in realization. The results of simulation studies and experiments on two paraplegic subjects show the superior performance of the leg power control during different conditions of operation using HOSM control scheme. PMID:21096932

  3. 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

  4. 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.

  5. Reactivity controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle systems simulations - IJER

    DOE PAGESBeta

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

    2015-01-01

    In-cylinder blending of gasoline and diesel to achieve reactivity- controlled compression ignition (RCCI) has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion (CDC). The RCCI 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. However, the current range of the experimental RCCI engine map investigated here does not allow for RCCI operation over the entirety of somemore » drive cycles. A multi-mode RCCI strategy is employed where the engine switches from RCCI to CDC when speed and load fall outside of the experimentally determined RCCI range. The potential for RCCI 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 RCCI-enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode RCCI, CDC, and a 2009 port-fuel injected gasoline engine. Simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. RCCI fuel economy simulation results are compared with the same vehicle powered by a representative 2009 PFI gasoline engine over multiple drive cycles. Engine-out drive cycle emissions are compared to CDC, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.« less

  6. 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

  7. 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

  8. 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.

  9. A pH-Regulated Quality Control Cycle for Surveillance of Secretory Protein Assembly

    PubMed Central

    Vavassori, Stefano; Cortini, Margherita; Masui, Shoji; Sannino, Sara; Anelli, Tiziana; Caserta, Imma R.; Fagioli, Claudio; Mossuto, Maria F.; Fornili, Arianna; van Anken, Eelco; Degano, Massimo; Inaba, Kenji; Sitia, Roberto

    2013-01-01

    Summary To warrant the quality of the secretory proteome, stringent control systems operate at the endoplasmic reticulum (ER)-Golgi interface, preventing the release of nonnative products. Incompletely assembled oligomeric proteins that are deemed correctly folded must rely on additional quality control mechanisms dedicated to proper assembly. Here we unveil how ERp44 cycles between cisGolgi and ER in a pH-regulated manner, patrolling assembly of disulfide-linked oligomers such as IgM and adiponectin. At neutral, ER-equivalent pH, the ERp44 carboxy-terminal tail occludes the substrate-binding site. At the lower pH of the cisGolgi, conformational rearrangements of this peptide, likely involving protonation of ERp44’s active cysteine, simultaneously unmask the substrate binding site and −RDEL motif, allowing capture of orphan secretory protein subunits and ER retrieval via KDEL receptors. The ERp44 assembly control cycle couples secretion fidelity and efficiency downstream of the calnexin/calreticulin and BiP-dependent quality control cycles. PMID:23685074

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  16. 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.

  17. Asymmetric control of cycle period by the spinal locomotor rhythm generator in the adult cat.

    PubMed

    Frigon, Alain; Gossard, Jean-Pierre

    2009-10-01

    During walking, a change in speed is accomplished by varying the duration of the stance phase, while the swing phase remains relatively invariant. To determine if this asymmetry in the control of locomotor cycles is an inherent property of the spinal central pattern generator (CPG), we recorded episodes of fictive locomotion in decerebrate cats with or without a complete spinal transection (acute or chronic). During fictive locomotion, stance and swing phases typically correspond to extension and flexion phases, respectively. The extension and flexion phases were determined by measuring the duration of extensor and flexor bursts, respectively. In the vast majority of locomotor episodes, cycle period varied more with the extension phase. This was found without phasic sensory feedback, supraspinal structures, pharmacology or sustained stimulation. We conclude that the control of walking speed is governed by an asymmetry within the organization of the spinal CPG, which can be modified by extraneous factors. PMID:19675066

  18. Weak-field multiphoton femtosecond coherent control in the single-cycle regime.

    PubMed

    Chuntonov, Lev; Fleischer, Avner; Amitay, Zohar

    2011-03-28

    Weak-field coherent phase control of atomic non-resonant multiphoton excitation induced by shaped femtosecond pulses is studied theoretically in the single-cycle regime. The carrier-envelope phase (CEP) of the pulse, which in the multi-cycle regime does not play any control role, is shown here to be a new effective control parameter that its effect is highly sensitive to the spectral position of the ultrabroad spectrum. Rationally chosen position of the ultrabroadband spectrum coherently induces several groups of multiphoton transitions from the ground state to the excited state of the system: transitions involving only absorbed photons as well as Raman transitions involving both absorbed and emitted photons. The intra-group interference is controlled by the relative spectral phase of the different frequency components of the pulse, while the inter-group interference is controlled jointly by the CEP and the relative spectral phase. Specifically, non-resonant two- and three-photon excitation is studied in a simple model system within the perturbative frequency-domain framework. The developed intuition is then applied to weak-field multiphoton excitation of atomic cesium (Cs), where the simplified model is verified by non-perturbative numerical solution of the time-dependent Schrödinger equation. We expect this work to serve as a basis for a new line of femtosecond coherent control experiments. PMID:21451714

  19. 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. PMID:25269759

  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. 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.

  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. PMID:26082757

  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. The scavenging processes controlling the seasonal cycle in Arctic sulphate and black carbon aerosol

    NASA Astrophysics Data System (ADS)

    Browse, J.; Carslaw, K. S.; Arnold, S. R.; Pringle, K.; Boucher, O.

    2012-08-01

    The seasonal cycle in Arctic aerosol is typified by high concentrations of large aged anthropogenic particles transported from lower latitudes in the late Arctic winter and early spring followed by a sharp transition to low concentrations of locally sourced smaller particles in the summer. However, multi-model assessments show that many models fail to simulate a realistic cycle. Here, we use a global aerosol microphysics model (GLOMAP) and surface-level aerosol observations to understand how wet scavenging processes control the seasonal variation in Arctic black carbon (BC) and sulphate aerosol. We show that the transition from high wintertime concentrations to low concentrations in the summer is controlled by the transition from ice-phase cloud scavenging to the much more efficient warm cloud scavenging in the late spring troposphere. This seasonal cycle is amplified further by the appearance of warm drizzling cloud in the late spring and summer boundary layer. Implementing these processes in GLOMAP greatly improves the agreement between the model and observations at the three Arctic ground-stations Alert, Barrow and Zeppelin Mountain on Svalbard. The SO4 model-observation correlation coefficient (R) increases from: -0.33 to 0.71 at Alert (82.5° N), from -0.16 to 0.70 at Point Barrow (71.0° N) and from -0.42 to 0.40 at Zeppelin Mountain (78° N). The BC model-observation correlation coefficient increases from -0.68 to 0.72 at Alert and from -0.42 to 0.44 at Barrow. Observations at three marginal Arctic sites (Janiskoski, Oulanka and Karasjok) indicate a far weaker aerosol seasonal cycle, which we show is consistent with the much smaller seasonal change in the frequency of ice clouds compared to higher latitude sites. Our results suggest that the seasonal cycle in Arctic aerosol is driven by temperature-dependent scavenging processes that may be susceptible to modification in a future climate.

  5. The scavenging processes controlling the seasonal cycle in Arctic sulphate and black carbon aerosol

    NASA Astrophysics Data System (ADS)

    Pringle, K.; Browse, J.; Carslaw, K. S.; Arnold, S.; Boucher, O.

    2013-12-01

    The seasonal cycle in Arctic aerosol is typified by high concentrations of large aged anthropogenic particles transported from lower latitudes in the late Arctic winter and early spring followed by a sharp transition to low concentrations of locally sourced smaller particles in the summer. However, multi-model assessments show that many models fail to simulate a realistic cycle. Here, we use a global aerosol microphysics model (GLOMAP) and surface-level aerosol observations to understand how wet scavenging processes control the seasonal variation in Arctic black carbon (BC) and sulphate aerosol. We show that the transition from high wintertime concentrations to low concentrations in the summer is controlled by the transition from ice-phase cloud scavenging to the much more efficient warm cloud scavenging in the late spring troposphere. This seasonal cycle is amplified further by the appearance of warm drizzling cloud in the late spring and summer boundary layer. Implementing these processes in GLOMAP greatly improves the agreement between the model and observations at the three Arctic ground-stations Alert, Barrow and Zeppelin Mountain on Svalbard. The SO4 model-observation correlation coefficient (R) increases from: -0.33 to 0.71 at Alert (82.5N), from -0.16 to 0.70 at Point Barrow (71.0N) and from -0.42 to 0.40 at Zeppelin Mountain (78N). The BC model-observation correlation coefficient increases from -0.68 to 0.72 at Alert and from -0.42 to 0.44 at Barrow. Observations at three marginal Arctic sites (Janiskoski, Oulanka and Karasjok) indicate a far weaker aerosol seasonal cycle, which we show is consistent with the much smaller seasonal change in the frequency of ice clouds compared to higher latitude sites. Our results suggest that the seasonal cycle in Arctic aerosol is driven by temperature-dependent scavenging processes that may be susceptible to modification in a future climate.

  6. Sex hormones affect language lateralisation but not cognitive control in normally cycling women.

    PubMed

    Hodgetts, Sophie; Weis, Susanne; Hausmann, Markus

    2015-08-01

    This article is part of a Special Issue "Estradiol and Cognition". Natural fluctuations of sex hormones during the menstrual cycle have been shown to modulate language lateralisation. Using the dichotic listening (DL) paradigm, a well-established measurement of language lateralisation, several studies revealed that the left hemispheric language dominance was stronger when levels of estradiol were high. A recent study (Hjelmervik et al., 2012) showed, however, that high levels of follicular estradiol increased lateralisation only in a condition that required participants to cognitively control (top-down) the stimulus-driven (bottom-up) response. This finding suggested that sex hormones modulate lateralisation only if cognitive control demands are high. The present study investigated language lateralisation in 73 normally cycling women under three attention conditions that differed in cognitive control demands. Saliva estradiol and progesterone levels were determined by luminescence immunoassays. Women were allocated to a high or low estradiol group. The results showed a reduced language lateralisation when estradiol and progesterone levels were high. The effect was independent of the attention condition indicating that estradiol marginally affected cognitive control. The findings might suggest that high levels of estradiol especially reduce the stimulus-driven (bottom-up) aspect of lateralisation rather than top-down cognitive control. PMID:26145565

  7. Defects in G1-S cell cycle control in head and neck cancer: a review.

    PubMed

    Michalides, Rob J A M; van de Brekel, Michiel; Balm, Fons

    2002-07-01

    Tumors gradually develop as a result of a multistep acquisition of genetic alterations and ultimately emerge as selfish, intruding and metastatic cells. The genetic defects associated with the process of tumor progression affect control of proliferation, programmed cell death, cell aging, angiogenesis, escape from immune control and metastasis. Fundamental cancer research over the last thirty years has revealed a multitude of genetic alterations which specify more or less separate steps in tumor development and which are collectively responsible for the process of tumor progression. The genes affected play in normal cells a crucial role in control over cell duplication and the interaction between cells, and between cells and their direct surrounding. This is illustrated on control during the G1/S phase of the cell cycle by its ultimate regulators: cyclins and cyclin dependent kinases. These proteins not only control the transition through the G1/S phase of the cell cycle, but also serve as mediators of the interaction between cells, and between cells and their surrounding. Defaults in the regulation of these proteins are associated with tumor progression, and, therefore, serve as targets for therapy. Defaults in those genes are found in various tumor types, although some of those prevail in particular tumor types. In this review emphasis is given to the defaults that occur in head and neck cancer. PMID:12112544

  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

    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

  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. Biological control of terrestrial silica cycling and export fluxes to watersheds.

    PubMed

    Derry, Louis A; Kurtz, Andrew C; Ziegler, Karen; Chadwick, Oliver A

    2005-02-17

    Silicon has a crucial role in many biogeochemical processes--for example, as a nutrient for marine and terrestrial biota, in buffering soil acidification and in the regulation of atmospheric carbon dioxide. Traditionally, silica fluxes to soil solutions and stream waters are thought to be controlled by the weathering and subsequent dissolution of silicate minerals. Rates of mineral dissolution can be enhanced by biological processes. But plants also take up considerable quantities of silica from soil solution, which is recycled into the soil from falling litter in a separate soil-plant silica cycle that can be significant in comparison with weathering input and hydrologic output. Here we analyse soil water in basaltic soils across the Hawaiian islands to assess the relative contributions of weathering and biogenic silica cycling by using the distinct signatures of the two processes in germanium/silicon ratios. Our data imply that most of the silica released to Hawaiian stream water has passed through the biogenic silica pool, whereas direct mineral-water reactions account for a smaller fraction of the stream silica flux. We expect that other systems exhibiting strong Si depletion of the mineral soils and/or high Si uptake rates by biomass will also have strong biological control on silica cycling and export. PMID:15716949

  13. 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

  14. 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.

  15. 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

  16. Heat recovery steam generator outlet temperature control system for a combined cycle power plant

    SciTech Connect

    Martens, A.; Myers, G.A.; McCarty, W.L.; Wescott, K.R.

    1986-04-01

    This patent describes a command cycle electrical power plant including: a steam turbine and at least one set comprising a gas turbine, an afterburner and a heat recovery steam generator having an attemperator for supplying from an outlet thereof to the steam turbine superheated steam under steam turbine operating conditions requiring predetermined superheated steam temperature, flow and pressure; with the gas turbine and steam turbine each generating megawatts in accordance with a plant load demand; master control means being provided for controlling the steam turbine and the heat recovery steam generator so as to establish the steam operating conditions; the combination of: first control means responsive to the gas inlet temperature of the heat recovery steam generator and to the plant load demand for controlling the firing of the afterburner; second control means responsive to the superheated steam predetermined temperature and to superheated steam temperature from the outlet for controlling the attemperator between a closed and an open position; the first and second control means being operated concurrently to maintain the superheated steam outlet temperature while controlling the load of the gas turbine independently of the steam turbine operating conditions.

  17. Characterization and quenching of friction-induced limit cycles of electro-hydraulic servovalve control systems with transport delay.

    PubMed

    Wang, Yuan-Jay

    2010-10-01

    This paper develops a systematic and straightforward methodology to characterize and quench the friction-induced limit cycle conditions in electro-hydraulic servovalve control systems with transport delay in the transmission line. The nonlinear friction characteristic is linearized by using its corresponding describing function. The delay time in the transmission line, which could accelerate the generation of limit cycles is particularly considered. The stability equation method together with parameter plane method provides a useful tool for the establishment of necessary conditions to sustain a limit cycle directly in the constructed controller coefficient plane. Also, the stable region, the unstable region, and the limit cycle region are identified in the parameter plane. The parameter plane characterizes a clear relationship between limit cycle amplitude, frequency, transport delay, and the controller coefficients to be designed. The stability of the predicted limit cycle is checked by plotting stability curves. The stability of the system is examined when the viscous gain changes with respect to the temperature of the working fluid. A feasible stable region is characterized in the parameter plane to allow a flexible choice of controller gains. The robust prevention of limit cycle is achieved by selecting controller gains from the asymptotic stability region. The predicted results are verified by simulations. It is seen that the friction-induced limit cycles can be effectively predicted, removed, and quenched via the design of the compensator even in the case of viscous gain and delay time variations unconditionally. PMID:20542269

  18. Cell Cycle Control by the Master Regulator CtrA in Sinorhizobium meliloti

    PubMed Central

    Ferri, Lorenzo; Penterman, Jon; Fioravanti, Antonella; Brilli, Matteo; Mengoni, Alessio; Bazzicalupo, Marco; Viollier, Patrick H.; Walker, Graham C.; Biondi, Emanuele G.

    2015-01-01

    In all domains of life, proper regulation of the cell cycle is critical to coordinate genome replication, segregation and cell division. In some groups of bacteria, e.g. Alphaproteobacteria, tight regulation of the cell cycle is also necessary for the morphological and functional differentiation of cells. Sinorhizobium meliloti is an alphaproteobacterium that forms an economically and ecologically important nitrogen-fixing symbiosis with specific legume hosts. During this symbiosis S. meliloti undergoes an elaborate cellular differentiation within host root cells. The differentiation of S. meliloti results in massive amplification of the genome, cell branching and/or elongation, and loss of reproductive capacity. In Caulobacter crescentus, cellular differentiation is tightly linked to the cell cycle via the activity of the master regulator CtrA, and recent research in S. meliloti suggests that CtrA might also be key to cellular differentiation during symbiosis. However, the regulatory circuit driving cell cycle progression in S. meliloti is not well characterized in both the free-living and symbiotic state. Here, we investigated the regulation and function of CtrA in S. meliloti. We demonstrated that depletion of CtrA cause cell elongation, branching and genome amplification, similar to that observed in nitrogen-fixing bacteroids. We also showed that the cell cycle regulated proteolytic degradation of CtrA is essential in S. meliloti, suggesting a possible mechanism of CtrA depletion in differentiated bacteroids. Using a combination of ChIP-Seq and gene expression microarray analysis we found that although S. meliloti CtrA regulates similar processes as C. crescentus CtrA, it does so through different target genes. For example, our data suggest that CtrA does not control the expression of the Fts complex to control the timing of cell division during the cell cycle, but instead it negatively regulates the septum-inhibiting Min system. Our findings provide valuable

  19. 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

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

    SciTech Connect

    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.

  1. Entrained gasification combined-cycle control study. Volume 2. Results. Final report

    SciTech Connect

    Clark, J.; Denton, L.; Hashemi, M.; Joiner, J.; Smelser, S.; Chowaniec, C.; Hobbs, M.; Jennings, S.; Phelts, E.

    1980-07-01

    Two control strategies were evaluated for a new type of electric power plant as part of a large utility network. An entrained coal gasifier fuels a gas turbine/steam turbine combined-cycle unit forming the integrated plant which was simulated by computer to analyze alternative control strategies. Transient operation of this gasification-combined-cycle (GCC) plant was studied to determine open-loop response as a stand-alone plant, as well as closed-loop response while functioning in a typical utility power system. GCC plant performance during specified operating contingencies, such as equipment trip or emergency shutdown, was also studied. Features of the GCC plant as simulated include a single-stage entrained (Texaco) gasifier fed concurrently with a coal-water slurry and gaseous oxygen, a cold gas cleanup train with a physical absorption (Selexol) system for selective sulfur removal, and advanced gas turbine design gased upon 2400/sup 0/F combustor outlet temperature. Conclusions are as follows: The GCC plant may be controlled satisfactorily in either gasifier-lead or turbine-lead control mode. The absorber column consistently removed 90% H/sub 2/S in the raw fuel gas from high sulfur Illinois coal. GCC plant pressure control must be installed to minimize plant pressure transients at the absorber column. The local controllers adequately maintained the GCC plant operation during all the emergency upsets. The GCC plant responds well to typical variations in electric power demand. Supplemental fuel gas storage is not required. Oxygen plant can affect the response time of the GCC plant. Response rates of 3%/min at the oxygen plant would make the GCC plant very responsive to electrical load changes.

  2. 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.

  3. 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

  4. 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. PMID:23869434

  5. 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

  6. 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

  7. 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.

  8. Neutron Production from Feedback Controlled Thermal Cycling of a Pyroelectric Crystal Stack

    SciTech Connect

    Tang, V; Meyer, G; Schmid, G; Spadaccini, C; Kerr, P; Rusnak, B; Sampayan, S; Naranjo, B; Putterman, S

    2007-08-09

    The LLNL Crystal Driven Neutron Source is operational and has produced record ion currents of {approx}10 nA and neutron output of 1.9 ({+-}0.3) x 10{sup 5} per thermal cycle using a crystal heating rate of 0.2 C/s from 10 C to 110 C. A 3 cm diameter by 1 cm thick LiTaO{sub 3} crystal with a socket secured field emitter tip is thermally cycled with feedback control for ionization and acceleration of deuterons onto a deuterated target to produce D-D fusion neutrons. The entire crystal and temperature system is mounted on a bellows which allows movement of the crystal along the beam axis and is completely contained on a single small vacuum flange. The modular crystal assembly permitted experimental flexibility. Operationally, flashover breakdowns along the side of the crystal and poor emitter tip characteristics can limit the neutron source. The experimental neutron results extend earlier published work by increasing the ion current and pulse length significantly to achieve a factor-of-two higher neutron output per thermal cycle. These findings are reviewed along with details of the instrument.

  9. 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.

  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. 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

  12. Cyclin D1-Cdk4 controls glucose metabolism independently of cell cycle progression.

    PubMed

    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

    2014-06-26

    Insulin constitutes a principal evolutionarily conserved hormonal axis for maintaining glucose homeostasis; dysregulation of this axis causes diabetes. PGC-1α (peroxisome-proliferator-activated receptor-γ coactivator-1α) links insulin signalling to the expression of glucose and lipid metabolic genes. The histone acetyltransferase GCN5 (general control non-repressed protein 5) acetylates PGC-1α and suppresses its transcriptional activity, whereas sirtuin 1 deacetylates and activates PGC-1α. Although insulin is a mitogenic signal in proliferative cells, whether components of the cell cycle machinery contribute to its metabolic action is poorly understood. Here we report that in mice insulin activates cyclin D1-cyclin-dependent kinase 4 (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 identify a Cdk4 inhibitor that potently decreases PGC-1α acetylation. Insulin/GSK-3β (glycogen synthase kinase 3-beta) signalling induces cyclin D1 protein stability by sequestering cyclin D1 in the nucleus. In parallel, dietary amino acids increase hepatic cyclin D1 messenger RNA 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 hyperglycaemia. In diabetic models, cyclin D1-Cdk4 is chronically elevated and refractory to fasting/feeding transitions; nevertheless further activation of this kinase normalizes glycaemia. 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

  13. Live birth rates after combined adjuvant therapy in IVF-ICSI cycles: a matched case-control study.

    PubMed

    Motteram, C; Vollenhoven, B; Hope, N; Osianlis, T; Rombauts, L J

    2015-04-01

    The effectiveness of combined co-treatment with aspirin, doxycycline, prednisolone, with or without oestradiol patches, was investigated on live birth (LBR) rates after fresh and frozen embryo transfers (FET) in IVF and intracytoplasmic sperm injection cycles. Cases (n = 485) and controls (n = 485) were extensively matched in a one-to-one ratio on nine physical and clinical parameters: maternal age, body mass index, smoking status, stimulation cycle number, cumulative dose of FSH, stimulation protocol, insemination method, day of embryo transfer and number of embryos transferred. No significant differences were found in fresh cycles between cases and controls for the pregnancy outcomes analysed, but fewer surplus embryos were available for freezing in the combined adjuvant group. In FET cycles, LBR was lower in the treatment group (OR: 0.49, 95% CI 0.25 to 0.95). The lower LBR in FET cycles seemed to be clustered in patients receiving combined adjuvant treatment without luteal oestradiol (OR 0.37, 95% CI 0.17 to 0.80). No difference was found in LBR between cases and controls when stratified according to the number of previous cycles (<3 or ≥3). There is no benefit of this combined adjuvant strategy in fresh IVF cycles, and possible harm when used in frozen cycles. PMID:25676168

  14. Combined cycle electric power plant with coordinated plural feedback turbine control

    SciTech Connect

    Kiscaden, R.W.; Martz, L.F.; Uram, R.

    1980-01-22

    A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes a superheater tube through which a fluid, E.G. Water, is directed to be additionally heated into superheated steam by the exhaust gas turbine gases. An afterburner further heats the exhaust gas turbine gases passed to the superheater tube. The temperature of the gas turbine exhaust gases is sensed for varying the fuel flow to the afterburner by a fuel valve, whereby the temperatures of the gas turbine exhaust gases and therefore of the superheated steam, are controlled. A plant load demand error signal is utilized for correcting a coordinated gas turbine load reference and for trimming a feedforward afterburner control signal derived from the sensed gas turbine exhaust temperatures.

  15. Combined cycle electric power plant with feedforward afterburner temperature setpoint control

    SciTech Connect

    Uram, R.

    1982-06-08

    A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes a superheater tube through which a fluid, e.g. water, is directed to be additionally heated into superheated steam by the exhaust gas turbine gases. An afterburner further heats the exhaust gas turbine gases passed to the superheater tube. The temperature of the gas turbine exhaust gases is sensed for varying the fuel flow to the afterburner by a fuel valve, whereby the temperatures of the gas turbine exhaust gases and therefore of the superheated steam, are controlled. The afterburner fuel flow is controlled through a feedforward setpoint signal derived as a predetermined function of sensed gas turbine exhaust temperature.

  16. Limit cycle oscillation of missile control fin with structural non-linearity

    NASA Astrophysics Data System (ADS)

    Bae, J. S.; Lee, I.

    2004-01-01

    Non-linear aeroelastic characteristics of a deployable missile control fin with structural non-linearity are investigated. A deployable missile control fin is modelled as a two-dimensional typical section model. Doublet-point method is used for the calculation of supersonic unsteady aerodynamic forces, and aerodynamic forces are approximated by using the minimum-state approximation. For non-linear flutter analysis structural non-linearity is represented by an asymmetric bilinear spring and is linearized by using the describing function method. The linear and non-linear flutter analyses indicate that the flutter characteristics are significantly dependent on the frequency ratio. From the non-linear flutter analysis, various types of limit cycle oscillations are observed in a wide range of air speeds below or above the linear divergent flutter boundary. The non-linear flutter characteristics and the non-linear aeroelastic responses are investigated.

  17. 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.

  18. A possible role of actin in the mechanical control of the cell cycle.

    PubMed

    Tripathi, S C

    1989-01-01

    Sail-sheet Cultures (SSC) are those in which the cells are i) grown within the meshes of inert grids ii) exposed to nutrients from most sides iii) attached to one another only at the edges like sail of a yacht (hence, the name 'sail-sheet') and iv) have the advantage of three-dimensional structure similar to an in vivo situation. We grew fibroblasts from chicken heart explants as SSC and studied the effect of mechanical stretching on the F-actin content of these cells. This study was designed to investigate the hypothesis that the effect of tension on the cell cycle may be channeled through the microfilaments. Data from this preliminary study suggested that short-term mechanical stretching of sail-sheets, using low frequency tension (1.0 Hz), diminishes F-actin. Thus, it may be possible to relate the decrease in the F-actin content of these cells to the slowing down of their locomotory activity, possible rounding up, and division. This study might contribute to the understanding of the mechanical control of the cell cycle and be of relevance in the phenomena such as healing of wounds and control of the cell division in tumors. PMID:2620166

  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. Climatic Controls of Soil Carbon Cycling Across a Gradient of Sonoran Desert Ecosystems

    NASA Astrophysics Data System (ADS)

    Rasmussen, C.

    2009-04-01

    Arid and semiarid lands cover roughly 36% to 40% of global land area, highlighting the importance these ecosystems play in the global carbon cycle. The controls of arid and semiarid ecosystem carbon cycle processes, such as soil organic matter turnover and mineral weathering, remain poorly understood. To address this knowledge gap, we established a set of long-term soil monitoring sites across a gradient of semiarid ecosystems in the Sonoran Desert of the Southwestern USA. These sites were established as part of the Critical Zone Exploration Network (CZEN), sponsored by the US National Science Foundation. The primary objectives of the Sonoran Desert Environmental Gradient (SDEG) include: (i) characterizing climate forcing controls of soil physical, chemical and biological processes, and the flux of chemical species from soils to surface waters; and (ii) developing predictive models of carbon cycle response to climate and climate change. Particular attention is given to the bimodal precipitation regime characteristic of the SDEG ecosystems and the relative impact of warm versus cold precipitation on biogeochemical processes. The SDEG spans a steep elevation and environmental gradient on granitic parent materials near Tucson, Arizona, USA. Elevation ranges from 800-2650 m a.s.l. with concurrent shifts in climatic regime. Specifically, mean annual air temperature decreases (20-10 °C) and mean annual precipitation increases (30-85 cm) with elevation, with concomitant changes in vegetation from mixed desert-scrub (<1200m) to grass and oak woodlands (1200-1700 m) to pinyon-juniper woodland (1700-2000 m) and ponderosa pine and fir forest (>2000 m). We sampled soil and regolith material from each of vegetation community across the SDEG and established a long-term soil-moisture and temperature monitoring network. Pedon physicochemical data, coupled with elemental mass balance, radiocarbon analyses of soil organic matter, and terrestrial cosmogenic nuclide (10Be) analyses

  1. 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

  2. The scavenging processes controlling the seasonal cycle in Arctic sulphate and black carbon aerosol

    NASA Astrophysics Data System (ADS)

    Browse, J.; Carslaw, K. S.; Arnold, S. R.; Pringle, K.; Boucher, O.

    2012-01-01

    The seasonal cycle in Arctic aerosol is typified by high concentrations of large aged anthropogenic particles transported from lower latitudes in the late Arctic winter and early spring followed by a sharp transition to low concentrations of locally sourced smaller particles in the summer. However, multi-model assessments show that many models fail to simulate a realistic cycle. Here, we use a global aerosol microphysics model and surface-level aerosol observations to understand how wet scavenging processes control the seasonal variation in Arctic black carbon (BC) and sulphate aerosol concentrations. We show that the transition from high wintertime to low summertime Arctic aerosol concentrations is caused by the change from inefficient scavenging in ice clouds to the much more efficient scavenging in warm liquid clouds. This seasonal cycle is amplified further by the appearance of warm drizzling cloud in late spring and summer at a time when aerosol transport shifts mainly to low levels. Implementing these processes in a model greatly improves the agreement between the model and observations at the three Arctic ground-stations Alert, Barrow and Zeppelin Mountain on Svalbard. The SO4 model-observation correlation coefficient (R) increases from: -0.33 to 0.71 at Alert (82.5° N), from -0.16 to 0.70 at Point Barrow (71.0° N) and from -0.42 to 0.40 at Zeppelin Mountain (78° N) while, the BC model-observation correlation coefficient increases from -0.68 to 0.72 at Alert and from -0.42 to 0.44 at Barrow. Observations at three marginal Arctic sites (Janiskoski, Oulanka and Karasjok) indicate a far weaker aerosol seasonal cycle, which we show is consistent with the much smaller seasonal changes in ice clouds compared to the higher latitude sites. Our results suggest that the seasonal cycle in Arctic aerosol is driven by temperature-dependent scavenging processes that may be susceptible to modification in a future climate.

  3. Supervisory Feed-Forward Control for Real-Time Topping Cycle CHP Operation

    SciTech Connect

    Cho, Heejin; Luck, Rogelio; Chamra, Louay M.

    2010-03-01

    This paper presents an energy dispatch algorithm for real-time topping cycle Cooling, Heating, and Power (CHP) operation for buildings with the objective of minimizing the operational cost, primary energy consumption (PEC), or carbon dioxide emission (CDE). The algorithm features a supervisory feed-forward control for real-time CHP operation using short-term weather forecasting. The advantages of the proposed control scheme for CHP operation are (a) relatively simple and efficient implementation allowing realistic real-time operation , (b) optimized CHP operation with respect to operational cost, PEC, or CDE, and (c) increased site-energy consumption (SEC) resulting in less dependence on the electric grid. In the feed-forward portion of the control scheme, short-term electric, cooling, and heating loads are predicted using the U.S. Department of Energy (DOE) benchmark small office building model. The results are encouraging regarding the potential saving of operational cost, PEC, and CDE from using the control system for a CHP system with electric and thermal energy storages.

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

    PubMed Central

    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. PMID:25914634

  5. 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

  6. 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

  7. Cell cycle-controlled interaction of nucleolin with the retinoblastoma protein and cancerous cell transformation.

    PubMed

    Grinstein, Edgar; Shan, Ying; Karawajew, Leonid; Snijders, Peter J F; Meijer, Chris J L M; Royer, Hans-Dieter; Wernet, Peter

    2006-08-01

    Retinoblastoma protein (Rb) is a multifunctional tumor suppressor, frequently inactivated in certain types of human cancer. Nucleolin is an abundant multifunctional phosphoprotein of proliferating and cancerous cells, recently identified as cell cycle-regulated transcription activator, controlling expression of human papillomavirus type 18 (HPV18) oncogenes in cervical cancer. Here we find that nucleolin is associated with Rb in intact cells in the G1 phase of the cell cycle, and the complex formation is mediated by the growth-inhibitory domain of Rb. Association with Rb inhibits the DNA binding function of nucleolin and in consequence the interaction of nucleolin with the HPV18 enhancer, resulting in Rb-mediated repression of the HPV18 oncogenes. The intracellular distribution of nucleolin in epithelial cells is Rb-dependent, and an altered nucleolin localization in human cancerous tissues results from a loss of Rb. Our findings suggest that deregulated nucleolin activity due to a loss of Rb contributes to tumor development in malignant diseases, thus providing further insights into the molecular network for the Rb-mediated tumor suppression. PMID:16698799

  8. 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.

  9. Cell cycle control in bacteria and yeast: a case of convergent evolution?

    PubMed

    Brazhnik, Paul; Tyson, John J

    2006-03-01

    Superficially similar traits in phylogenetically unrelated species often result from adaptation to common selection pressures. Examples of convergent evolution are known at the levels of whole organisms, organ systems, gene networks and specific proteins. The phenotypic properties of living things, on the other hand, are determined in large part by complex networks of interacting proteins. Here we present a mathematical model of the network of proteins that controls DNA synthesis and cell division in the alpha-proteobacterium, Caulobacter crescentus. By comparing the protein regulatory circuits for cell reproduction in Caulobacter with that in budding yeast (Saccharomyces cerevisiae), we suggest that convergent evolution may have created similar molecular reaction networks in order to accomplish the same purpose of coordinating DNA synthesis to cell division. Although the genes and proteins involved in cell cycle regulation in prokaryotes and eukaryotes are very different and (apparently) phylogenetically unrelated, they seem to be wired together in similar regulatory networks, which coordinate cell cycle events by identical dynamical principles. PMID:16552176

  10. Controlling the duty cycle of holographic crossed gratings by in situ endpoint detection during development.

    PubMed

    Wang, Shiwei; Zeng, Lijiang

    2016-04-01

    A method of in situ development endpoint detection is proposed to control the duty cycle of holographic crossed gratings. Based on the observation that after the developer first touches the substrate surface the topography of the crossed grating undergoes an evolution process from a hole array of increasing diameter to a pillar array of decreasing diameter, we set up a development model. In this model, the shapes of both holes and pillars are assumed to have square in-plane cross sections, rotated 45° with respect to the main periodic directions, and straight side walls perpendicular to the grating plane. Thus, the main development process, including the transition from a hole array to a pillar array, can be characterized by a single parameter continuously, and the change of diffraction efficiency during the process can be theoretically calculated. Two different in situ development monitoring conditions were simulated and tested experimentally. Using this method, crossed gratings with various duty cycles were fabricated under different incident and monitoring conditions. PMID:27139670

  11. Seasonal patterns of photosynthetic capacity: photoperiodic control and its carbon cycling implications

    NASA Astrophysics Data System (ADS)

    Bauerle, W.; Oren, R.; Way, D.; Qian, S.; Stoy, P. C.; Thornton, P. E.; Bowden, J.; Hoffman, F. M.; Reynolds, R.

    2012-12-01

    While temperature is an important driver of seasonal changes in photosynthetic physiology, photoperiod also regulates leaf activity. Climate change will extend growing seasons if temperature cues predominate, but photoperiod-controlled species will show limited responsiveness to warming. We show that photoperiod explains more seasonal variation in photosynthetic activity across 23 tree species than temperature. Although leaves remain green, photosynthetic capacity peaks just after summer solstice and declines with decreasing photoperiod, before air temperatures peak. In support of these findings, saplings grown at constant temperature, but exposed to an extended photoperiod maintained high photosynthetic capacity, while photosynthetic activity declined in saplings experiencing a naturally shortening photoperiod; leaves remained equally green in both treatments. Incorporating a photoperiodic correction of photosynthetic physiology into a global-scale terrestrial carbon cycle model significantly improves predictions of seasonal atmospheric CO2 cycling, demonstrating the benefit of such a function in coupled climate system models. Accounting for photoperiod-induced seasonality in photosynthetic parameters reduces modeled global gross primary production ~4 PgC y-1, resulting in a ~2 PgC y-1 decrease of net primary production. Such a correction is also needed in models estimating current carbon uptake based on remotely-sensed greenness. Photoperiod-associated declines in photosynthetic capacity could limit autumn carbon gain in forests, even if warming delays leaf senescence. Assessments of late season carbon sequestration under a changing climate should focus on potential adverse impacts of warming via increased ecosystem respiration.

  12. Octave-spanning spectral phase control for single-cycle bi-photons

    NASA Astrophysics Data System (ADS)

    Shaked, Yaakov; Yefet, Shai; Geller, Tzahi; Pe'er, Avi

    2015-07-01

    The quantum correlation of octave-spanning time-energy entangled bi-photons can be as short as a single optical cycle. Many experiments designed to explore and exploit this correlation require a uniform spectral phase (transform-limited) with very low loss. So far, transform-limited single-cycle bi-photons have not been demonstrated, primarily due to the lack of precise, broadband control of their spectral phase. Here, we demonstrate the correction of the spectral-phase of near-octave spanning bi-photons to \\varphi \\lt π /20 over an octave in frequency ≈ 1330-2600 nm). Using a prism-pair with an effectively negative separation for shaping the bi-photons’ spectral phase, we obtain a tuned, very low-loss compensation of both the second and fourth dispersion orders. An essential requisite for precise tuning over such a broad bandwidth is a measure of the spectral phase that provides feedback for the tuning even when the overall dispersion is far from compensated. This is achieved by a non-classical bi-photon interference, which enables direct verification of the corrected bi-photon spectral phase.

  13. Rapid Quench Cold-Seal Apparatus with Computer-Controlled Pressure and Temperature Cycling

    NASA Astrophysics Data System (ADS)

    Johnston, A.; Senkovich, D.

    2007-12-01

    We have constructed two computer-controlled, rapid quench, hydrothermal apparatuses that are ideal for experimentation on volcanological, geothermal, and ore deposit research problems. The devices can achieve maximum pressures of about 2 kbar and temperatures to 1100C, have the ability for experiments to be quenched very rapidly in a water-cooled environment, and are interfaced with computers which can control any regimen of pressure and/or temperature cycling that may be desired, accomplished via Lab-View software and data acquisition and motion control boards from National Instruments. The rapid quench aspects of the design were developed originally by Dr. Phil Ihinger and have subsequently been adopted by many labs around the world; a good summary description of these aspects of the equipment, and the use of filler-rods for controlling redox conditions in such equipment, are provided by Matthews et al. (2004, Am. Mineral., 88: 701-707). Our design has fixed Rene 41 pressure vessels, furnaces that are raised and lowered by computer controlled pneumatic cylinders and water cooling systems that are controlled by computer operated solenoid valves. The novel feature of our design is the pressure generation and control systems. We coupled the seal-ends of commercially available (HIP) pressure generators to shop-built linear actuators consisting of nearly frictionless ball lead screws within thick walled stainless steel housings. These in turn are driven by NEMA size 23 stepper motors coupled to 100:1 gear reduction units. The actuators require 21 revolutions to achieve their full stroke of 12.7 cm which displaces about 10 cc of fluid. Operating the motors at the relatively low resolution of 800 steps per revolution leads to about 132,000 steps per cm of travel of the pressure-generating piston, providing exceptionally high precision and excellent pressure control. Instantaneous decompression can be achieved by simply opening a valve while motor-controlled

  14. 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

  15. 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. PMID:25981938

  16. 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

  17. 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

  18. 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. PMID:25143350

  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. Dose and cycle of insecticide applications in the control of malaria

    PubMed Central

    Macdonald, G.; Davidson, G.

    1953-01-01

    The authors first review the doses and cycles of application normally recommended in different parts of the world for DDT, BHC, and dieldrin in controlling malaria, and then discuss the experimental evidence concerning their actual efficacy in the field. The irritant effect of the various insecticides is compared, DDT being found the most irritant and dieldrin the least. BHC appears to be highly irritant when solid, but not when vaporized. The problem of the application of residual insecticides to absorbent surfaces, such as mud, is considered; the wettable powders are generally accepted as the most efficient formulation for such surfaces, but even with these a marked loss in toxicity may occur, requiring higher initial doses and more frequent application than on non-absorbent surfaces. With volatile insecticides, such as BHC, some degree of absorption slows down the loss by volatilization, but at the usual field dosages of 0.1 g and 0.2 g of gamma-BHC per m2 the decline in toxicity is still rapid. Experiments have also shown that mixtures of DDT and BHC may, in some circumstances, combine the initial high kill of the latter with the persistent moderate kill of the former. Considering the insecticidal efficiency needed for the control of malaria, the authors find that most natural circumstances would be met by attaining a mortality-rate of about 65% of mosquitos entering treated shelters; 85% mortality would be suitable for the most severe conditions and 65% mortality for controlling moderate transmission by endophilic mosquitos. PMID:13141131

  2. 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.

  3. Clusterin and DNA repair: a new function in cancer for a key player in apoptosis and cell cycle control.

    PubMed

    Shannan, B; Seifert, M; Boothman, D A; Tilgen, W; Reichrath, J

    2006-09-01

    The glycoprotein clusterin (CLU), has two known isoforms generated in human cells. A nuclear form of CLU protein (nCLU) is pro-apoptotic, while a secretory form (sCLU) is pro-survival. Both forms are implicated in various cell functions, including DNA repair, cell cycle regulation, and apoptotic cell death. CLU expression has been associated with tumorigenesis and the progression of various malignancies. In response to DNA damage, cell survival can be enhanced by activation of DNA repair mechanisms, while simultaneously stimulating energy-expensive cell cycle checkpoints that delay the cell cycle progression to allow more time for DNA repair. This review summarizes our current understanding of the role of clusterin in DNA repair, apoptosis, and cell cycle control and the relevance. PMID:17048076

  4. 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

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

    PubMed

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

    2012-02-01

    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 G(0)/G(1). 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 G(0). 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 G(0)/G(1), but also for activation in S, G(2) 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

  6. Mechanisms of Cell Cycle Control Revealed by a Systematic and Quantitative Overexpression Screen in S. cerevisiae

    PubMed Central

    Niu, Wei; Li, Zhihua; Zhan, Wenjing; Iyer, Vishwanath R.; Marcotte, Edward M.

    2008-01-01

    Regulation of cell cycle progression is fundamental to cell health and reproduction, and failures in this process are associated with many human diseases. Much of our knowledge of cell cycle regulators derives from loss-of-function studies. To reveal new cell cycle regulatory genes that are difficult to identify in loss-of-function studies, we performed a near-genome-wide flow cytometry assay of yeast gene overexpression-induced cell cycle delay phenotypes. We identified 108 genes whose overexpression significantly delayed the progression of the yeast cell cycle at a specific stage. Many of the genes are newly implicated in cell cycle progression, for example SKO1, RFA1, and YPR015C. The overexpression of RFA1 or YPR015C delayed the cell cycle at G2/M phases by disrupting spindle attachment to chromosomes and activating the DNA damage checkpoint, respectively. In contrast, overexpression of the transcription factor SKO1 arrests cells at G1 phase by activating the pheromone response pathway, revealing new cross-talk between osmotic sensing and mating. More generally, 92%–94% of the genes exhibit distinct phenotypes when overexpressed as compared to their corresponding deletion mutants, supporting the notion that many genes may gain functions upon overexpression. This work thus implicates new genes in cell cycle progression, complements previous screens, and lays the foundation for future experiments to define more precisely roles for these genes in cell cycle progression. PMID:18617996

  7. 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.

  8. 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

  9. 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.

  10. Balancer control device for multiple-cylinder four-cycle engine

    SciTech Connect

    Morita, S.; Tanaka, H.; Umemura, K.

    1986-09-02

    In a multiple-cylinder four-cycle engine which can be operated in two-cylinder operation in which two cylinders are operated so that the power stroke of one cylinder occurs with a crank angle phase difference of 360/sup 0/ with respect to the power stroke of the other cylinder, a balancer control device is described comprising a balancer which is driven during the two-cylinder operation of the engine to generate a primary vibration generating moment which reduces the primary vibration generating moment imparted to the engine structure due to explosion during the two-cylinder operation. It also includes an engine load detecting means for detecting engine load, an engine rpm detecting means for detecting the engine speed and a balancer changing means which changes the primary vibration generating moment of the balancer according to the operating condition of the engine so that the primary vibration generating moment of the balancer approximates the primary vibration generating moment of the engine structure due to explosion thereby suppressing the primary vibration generating moment of the engine structure over the entire operating range during the two-cylinder operation.

  11. 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.

  12. 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.

  13. 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. PMID:20599249

  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. PMID:23856224

  15. Controls on the speed of spring: challenges for terrestrial carbon cycle models

    NASA Astrophysics Data System (ADS)

    Gu, L.; Fu, Y.

    2010-12-01

    Numerous studies have investigated how climate change will affect the phenology of terrestrial ecosystems, particularly the start of the growing season. However, little attention has been paid to the issue of how fast the growing season will proceed once it has started and what control this speed. Yet the speed of spring, measured by the temporal rate of recovery of plant community photosynthesis, determines annual carbon budget in a fundamental way. Using data from Fluxnet, a global network of eddy covariance flux sites, we studied the recovery rate of canopy photosynthetic capacity across vegetation types. We found that: - Air temperature is the dominant factor that controls the spring recovery (both the timing and the recovery rate) of canopy photosynthesis in northern ecosystems. - However, it is the increasing rate, rather than the absolute value, of daily mean air temperature (other than minimum, maximum air temperature or soil temperature) that determines the peak recovery rate of canopy photosynthetic capacity. - The gross ecosystem productivity in late-half year affects the peak recovery rate of canopy photosynthetic capacity in the following spring, presumably through the influence of substrate supply for metabolism to support new shoot and leaf growth. - Deciduous broad leaf forests and grasslands are more sensitive to temperature change in spring than evergreen needle leaf forests, probably due to the differences in the life history strategy between deciduous and evergreen leaves. These findings suggest new requirements for climate models and point to new processes that should be represented in terrestrial carbon cycle models to improve future predictions of land carbon sinks and sources.

  16. 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

  17. 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

  18. Novel control of S-phase of the cell cycle by ubiquitin conjugating enzyme H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Timely degradation of regulatory proteins by the ubiquitin proteolytic pathway (UPP) is an established paradigm of cell cycle regulation during the G2/M and G1/S transitions. Less is known about roles for the UPP during S phase. Here we present evidence that dynamic cell cycle dependent changes in l...

  19. 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.

  20. Autocrine and exogenous transforming growth factor beta control cell cycle inhibition through pathways with different sensitivity.

    PubMed

    Wang, Jing; Sergina, Natalia; Ko, Tien C; Gong, Jiangeng; Brattain, Michael G

    2004-09-17

    Human colon carcinoma cells HCT116 that lack transforming growth factor beta (TGF-beta) type II receptor (RII) demonstrated restoration of autocrine TGF-beta activity upon reexpression of RII without restoring inhibitory responses to exogenous TGF-beta treatment. RII transfectants (designated RII Cl 37) had a longer lag phase relative to NEO-transfected control cells (designated NEO pool) before entering exponential growth in tissue culture. The prolonged growth arrest of RII Cl 37 cells was associated with markedly reduced cyclin-dependent kinase (CDK)2 activity. Our results demonstrate that p21 induction by autocrine TGF-beta is responsible for reduced CDK2 activity, which at least partially contributes to prolonged growth arrest and reduced cell proliferation in RII Cl 37 cells. In contrast to RII transfectants, HCT116 cells transfected with chromosome 3 (designated HCT116Ch3), which bears the RII gene, restored the response to exogenous TGF-beta as well as autocrine TGF-beta activity. Autocrine TGF-beta activity in HCT116Ch3 cells induced p21 expression as seen in RII Cl 37 cells; however, in addition to autocrine activity, HCT116Ch3 cells responded to exogenous TGF-beta as decreased CDK4 expression and reduced pRb phosphorylation mediated a TGF-beta inhibitory response in these cells. These results indicate that autocrine TGF-beta regulates the cell cycle through a pathway different from exogenous TGF-beta in the sense that p21 is a more sensitive effector of the TGF-beta signaling pathway, which can be induced and saturated by autocrine TGF-beta, whereas CDK4 inhibition is a less sensitive effector, which can only be activated by high levels of exogenous TGF-beta PMID:15271980

  1. 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

  2. The Forkhead Transcription Factor FOXM1 Controls Cell Cycle-Dependent Gene Expression through an Atypical Chromatin Binding Mechanism

    PubMed Central

    Chen, Xi; Müller, Gerd A.; Quaas, Marianne; Fischer, Martin; Han, Namshik; Stutchbury, Benjamin; Engeland, Kurt

    2013-01-01

    There are nearly 50 forkhead (FOX) transcription factors encoded in the human genome and, due to sharing a common DNA binding domain, they are all thought to bind to similar DNA sequences. It is therefore unclear how these transcription factors are targeted to specific chromatin regions to elicit specific biological effects. Here, we used chromatin immunoprecipitation followed by sequencing (ChIP-seq) to investigate the genome-wide chromatin binding mechanisms used by the forkhead transcription factor FOXM1. In keeping with its previous association with cell cycle control, we demonstrate that FOXM1 binds and regulates a group of genes which are mainly involved in controlling late cell cycle events in the G2 and M phases. However, rather than being recruited through canonical RYAAAYA forkhead binding motifs, FOXM1 binding is directed via CHR (cell cycle genes homology region) elements. FOXM1 binds these elements through protein-protein interactions with the MMB transcriptional activator complex. Thus, we have uncovered a novel and unexpected mode of chromatin binding of a FOX transcription factor that allows it to specifically control cell cycle-dependent gene expression. PMID:23109430

  3. 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. PMID:26751966

  4. 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.

  5. Plasma-based generation and control of a single few-cycle high-energy ultrahigh-intensity laser pulse.

    PubMed

    Tamburini, M; Di Piazza, A; Liseykina, T V; Keitel, C H

    2014-07-11

    A laser-boosted relativistic solid-density paraboloidal foil is known to efficiently reflect and focus a counterpropagating laser pulse. Here we show that in the case of an ultrarelativistic counterpropagating pulse, a high-energy and ultrahigh-intensity reflected pulse can be more effectively generated by a relatively slow and heavy foil than by a fast and light one. This counterintuitive result is explained with the larger reflectivity of a heavy foil, which compensates for its lower relativistic Doppler factor. Moreover, since the counterpropagating pulse is ultrarelativistic, the foil is abruptly dispersed and only the first few cycles of the counterpropagating pulse are reflected. Our multidimensional particle-in-cell simulations show that even few-cycle counterpropagating laser pulses can be further shortened (both temporally and in the number of laser cycles) with pulse amplification. A single few-cycle, multipetawatt laser pulse with several joules of energy and with a peak intensity exceeding 10(23)  W/cm(2) can be generated already employing next-generation high-power laser systems. In addition, the carrier-envelope phase of the generated few-cycle pulse can be tuned provided that the carrier-envelope phase of the initial counterpropagating pulse is controlled. PMID:25062199

  6. 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

  7. Influence of tidal cycles on the endocrine control of reproductive activity in common snook (Centropomus undecimalis).

    PubMed

    Rhody, Nicole R; Davie, Andrew; Zmora, Nilli; Zohar, Yonathan; Main, Kevan L; Migaud, Hervé

    2015-12-01

    The aim of our study was to confirm the role of tidal pattern on the coordination of oocyte maturation and spawning in common snook Centropomus undecimalis. To do so, we studied oocyte maturation during the spawning season in relation to the tidal pattern in both males and females by means of histology and hormonal profiling along the pituitary-gonadal axis. Plasma LH levels, as well as transcript levels of gonadotropin genes (fshβ and lhβ) from the pituitaries of sexually mature male and female common snook were analyzed using a heterologous ELISA and quantitative RT-PCR, respectively. The fshβ and lhβ cDNAs were isolated and phylogenetic analysis of the deduced amino acid sequences revealed strong identity with other teleosts (75-90%). A strong link was found between tide and follicular development irrespective of the time of the day: female snook sampled on the rising tide were all found to have oocytes in the Secondary Growth Stage whereas females sampled at high tide or on the falling tide had oocytes in the later stages of maturation and ovulation. In addition, LH plasma and mRNA levels of fshβ and lhβ increased during the later stages of vitellogenesis peaking at ovulation in females. Plasma estradiol and testosterone significantly increased in late vitellogenesis (Secondary Growth Stage) and oocyte maturation (Eccentric Germinal Vesicle Step) respectively. Among male common snook sampled, no correlation was identified between tide and gonadal development. In addition, lhβ mRNA expression in males peaked at the mid germinal epithelium stage as for testosterone and 11-KT in the blood while fshβ expression and plasma LH levels peaked at late germinal epithelium stage. This study confirms the role played by tidal cycle on the entrainment of the later stages of oogenesis of common snook and provides a better understanding of the link between environmental and endocrine control of reproduction in this species. PMID:26261080

  8. The Developmental Competence of Oocytes Retrieved from The Leading Follicle in Controlled Ovarian Stimulated Cycles

    PubMed Central

    Braga, Daniela Paes de Almeida Ferreira; Bonetti, Tatiana Carvalho de Souza; da Silva, Ismael Dale Cotrim Guerreiro; Setti, Amanda Souza; Iaconelli, Assumpto Jr; Borges, Edson Jr

    2013-01-01

    Background: This study compares the developmental capacity of gametes retrieved from the largest follicle with small follicles of a cohort in controlled ovarian stimulated cycles. Materials and Methods: This prospective study performed in a private assisted fertilization center included 1016 follicles collected from 96 patients who underwent intra cytoplasmic sperm injection (ICSI). After follicular aspiration, oocytes were assigned to two groups according to the diameter of the derived follicle. The large follicle group (n=96) comprised oocytes derived from the leading follicle of the cohort and the small follicle group (n=920) consisted oocytes derived from the smaller follicles of the cohort. The fertilization and percentage of topquality embryos were compared between groups by Chi-square or Fisher’s exact test, where appropriate. The effect of the follicular diameter on oocyte dimorphism was assessed by binary logistic regression. Results: A significantly higher percentage of oocytes derived from the leading follicle were in the metaphase II (MII) stage (100 vs. 70.0%, p<0.001). However we observed no significant differences regarding the percentage of degenerated oocytes between the large (6.25%) and small follicle (5.0%) groups (p=0.550). Regression analysis demonstrated a nearly two-fold increase in the incidence of vacuoles in oocytes derived from the largest follicle of the cohort (OR: 1.81, p=0.046). The fertilization rate (50.0 vs. 38.8%, p=0.038) and the percentage of top quality embryos (84.7 vs. 76.4%, p=0.040) were significantly higher for oocytes derived from the largest follicle. However, the percentage of abnormal fertilized oocytes was equally distributed between the large follicle (15.0%) and small follicle (12. 8%) groups (p=0.550). Conclusion: Our data suggest that intrafollicular mechanisms within the larger follicle of the cohort may allow for these follicles to amplify the responsiveness to exogenous gonadotropin, which leads to the

  9. 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

  10. Controlled, reversible suppression of estrous cycles in beef heifers and cows using agonists of gonadotropin-releasing hormone.

    PubMed

    D'Occhio, M J; Aspden, W J; Whyte, T R

    1996-01-01

    Agonists of GnRH were examined for their potential to achieve controlled, reversible suppression of estrous cycles in beef cattle. In Exp. 1, cyclic heifers received two (Group B2) or four (Group B4) buserelin (D-Ser[Bu(t)]6-Pro9-LHRH[1-9] nonapeptide ethylamide) implants and degree of cessation of estrous cycles was monitored. Treatment with buserelin caused estrous cycles to cease, as indicated by basal (.2 ng/mL) concentrations of progesterone, for 48.4 +/- 3.8 d (mean +/- SEM) in Group B2, which was less (P = .6) than the 87.4 +/- 17.4 d in Group B4. In Exp. 2, heifers treated with one (Group D1) or two (Group D2) implants of deslorelin (D-Trp6-Pro9-des-Gly10-LHRH ethylamide) had basal progesterone concentrations for 203 +/- 26 d (Group D1) and 170 +/- 28 d (Group D2; P > .05). In Exp. 3, stage of the estrous cycle was synchronized in cows, and, on d 7 of the ensuing cycle, cows received four deslorelin implants for 28 (Group D28) or 56 d (Group D56). Treatment with deslorelin induced an acute increase in plasma concentrations of immunoactive and bioactive LH, which remained increased over 7 d of observation. Based on profiles of progesterone, cows did not develop a functional corpus luteum during deslorelin treatment. Days to first and second estrus after implant removal were similar for cows in Group D28 (23.6 +/- 2.1 and 40.2 +/- 4.2 d, respectively) and Group D56 (21.5 +/- 3.3 and 44.3 +/- 2.9 d). The findings indicated that GnRH agonists block estrous cycles in cattle. Also, estrous cycles returned after discontinuation of treatment. Furthermore, the consistent and predictable responses detected in cows after implant removal indicated that agonists should be suitable for achieving a controlled, reversible suppression of estrous cycles in cattle. PMID:8778103

  11. 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.

  12. 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.

  13. Operational, control and protective system transient analyses of the closed-cycle GT-HTGR power plant

    NASA Astrophysics Data System (ADS)

    Openshaw, F. L.; Chan, T. W.

    1980-11-01

    This paper presents a description of the analyses of the control/protective system preliminary designs for the gas turbine high-temperature gas-cooled reactor (GT-HTGR) power plant. The purpose of these systems is the control and safe operation of the plant in accordance with utility practice for large nuclear generation stations, and in the event of an abnormal or accident condition to shut the plant down in an orderly manner and maintain it in a safe shutdown condition. Several unique characteristics inherent in the operation of the closed-cycle multiple-loop GT-HTGR design have presented special modeling and/or control design requirements or resulted in unusual conditions. The GT-HTGR dynamic modeling, control/protective system design, and transient analyses are illustrated in this paper through discussion of a few selected transient events and the special modeling and control operation for these events.

  14. 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

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

    PubMed Central

    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

  16. 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

  17. 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.

  18. 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 (...

  19. 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

  20. Ichno-sedimentological record of short-term climate-controlled redox events and cycles in organic-rich strata

    SciTech Connect

    Savrda, C.E. ); Bottjher, D.J. ); Ozalas, K. )

    1990-05-01

    Reduced rates of biochemical degradation of organic matter in oxygen-depleted marine settings generally result in the accumulation of laminated strata with high hydrocarbon source potential. Periods of improved oxygenation, during which the quantity and quality of organic matter are effectively reduced, are reflected by interbedded bioturbated intervals. Such benthic redox excursions may reflect variable paleooceanographic responses to climatic events or cycles. The potential role of climate in the short-term modulation of source rock potential is exemplified by bioturbated intervals within three predominantly laminated organic-rich units. The Jurassic Posidonia Shale (Germany) contains bioturbated beds whose ichnologic characteristics reflect a spectrum from short, low-magnitude redox events to longer episodes of greater magnitude. The character and distribution of these event beds appear to be controlled by sea level mediated variations in the frequency and intensity of storm-induced basin turnover. Bioturbated beds of the Upper Cretaceous Niobrara Formation (Colorado) are characterized by four oxygen-related ichnocoenoses, the distribution of which reflects cyclic variations in redox conditions. Relationships between paleooxygenation and organic-carbon and carbonate contents, and estimated cycle periodicities, suggest that redox variations were controlled by wet-dry climatic cycles modulated by the Milankovitch cycle of axial precession. Bioturbated beds within slope and basinal facies of the Miocene Monterey Formation (California) are variable in character, reflecting differences in duration and magnitude of associated oxygenation episodes, and may be in response to short-term variations in wind-stress-induced upwelling and/or ice-volume-controlled eustatic sea level changes.

  1. The influence of abiotic controls and management intensity on phosphorus cycling in established grassland and forest ecosystems

    NASA Astrophysics Data System (ADS)

    Alt, F.; Oelmann, Y.; Wilcke, W.

    2011-12-01

    It is commonly assumed that the bioavailability and cycling of phosphorus (P) is mainly controlled by abiotic soil properties including soil pH and the concentrations and reactivities of clay minerals, CaCO3 and Al/Fe oxides In managed ecosystems, kind, timing and duration of P additions and type and amount of harvested biomass are the major input and output fluxes. Our objective was to disentangle the effects of abiotic controls, and type and intensity of management on the P cycle in soils of temperate grasslands and forests of different management intensity in three regions across Germany in the frame of the Biodiversity Exploratories project. The pH value was the most important variable explaining P concentrations and partitioning in soil and changes in pH are the main mechanism how land-use is affecting the P cycle. However, after the influence of pH was accounted for in a sequential statistical approach, land-use intensity, classified according to the extent of annual biomass removal, explained a significant (P < 0.05) part of the variance in the contributions of several P fractions to total P (TP) among all studied regions and land-use types. In grassland soils of highly diverse systems (up to 57 plant species) in one of the study regions, the Schwäbische Alb, a mid-range mountain area on limestone where soils showed a limited variation in pH in the carbonate buffer range, pedogenic Fe oxide concentrations, fertilizer-P application rates, and TP concentrations in soil explained more than half of the variation in bioavailable inorganic (Pi) concentrations extracted with NaHCO3 in soil. Our results demonstrate that mainly soil pH and mineralogical composition, and intensity of management of the managed ecosystems are significant controls of the P cycle determining the size of bioavailable P pool in soil.

  2. 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

  3. 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

  4. 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.

  5. Pegram Lectures: 'Controlling the Cell Cycle' and 'The Great Ideas of Biology'

    SciTech Connect

    Paul Nurse

    2009-03-18

    Nurse explains that growth and reproduction of all living organisms are dependent on the cell cycle, the process that leads to cell division. He also discusses three important theories that have influenced the course of biology: gene theory, the proposal that the cell is the fundamental unit of all life, and Charles Darwin's theory of evolution by natural selection, which in 2009 is 150 years old.

  6. Control of DNA polymerase λ stability by phosphorylation and ubiquitination during the cell cycle

    PubMed Central

    Wimmer, Ursula; Ferrari, Elena; Hunziker, Peter; Hübscher, Ulrich

    2008-01-01

    DNA polymerase (Pol) λ is a DNA repair enzyme involved in base excision repair, non-homologous end joining and translesion synthesis. Recently, we identified Pol λ as an interaction partner of cyclin-dependent kinase 2 (CDK2) that is central to the cell cycle G1/S transition and S-phase progression. This interaction leads to in vitro phosphorylation of Pol λ, and its in vivo phosphorylation pattern during cell cycle progression mimics the modulation of CDK2/cyclin A. Here, we identify several phosphorylation sites of Pol λ. Experiments with phosphorylation-defective mutants suggest that phosphorylation of Thr 553 is important for maintaining Pol λ stability, as it is targeted to the proteasomal degradation pathway through ubiquitination unless this residue is phosphorylated. In particular, Pol λ is stabilized during cell cycle progression in the late S and G2 phases. This most likely allows Pol λ to correctly conduct repair of damaged DNA during and after S phase. PMID:18688254

  7. 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

  8. 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. PMID:22613743

  9. 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

  10. 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.

  11. 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

  12. 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. PMID:11415276

  13. Creation and control of single attosecond XUV pulse by few-cycle intense laser pulse

    NASA Astrophysics Data System (ADS)

    Carrera, Juan J.; Tong, X. M.; Chu, Shih-I.

    2006-05-01

    We present a theoretical investigation of the mechanisms responsible for the production of single atto-second pulse by using few-cycle intense laser pulses. The atto-second XUV spectral is calculated by accurately integrating the time- dependent Schr"odinger equation. The detailed mechanism for the production of the XUV pulse are also corroborated by analyzing the classical trajectories of the electron. Our study shows that the first return of the rescattering electron is responsible for the high energy atto-second pulse. Furthermore, we can optimize the production of atto-second XUV pulses by modifying the trajectory of the rescattering electron by tuning the laser field envelope.

  14. Nonlinear Optics with Phase-Controlled Pulses in the Sub-Two-Cycle Regime

    SciTech Connect

    Morgner, U.; Ell, R.; Metzler, G.; Schibli, T. R.; Kartner, 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 5fs 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.

  15. A Metabolic Control Analysis of the Glutamine Synthetase/Glutamate Synthase Cycle in Isolated Barley (Hordeum vulgare L.) Chloroplasts.

    PubMed Central

    Baron, A. C.; Tobin, T. H.; Wallsgrove, R. M.; Tobin, A. K.

    1994-01-01

    Ammonia assimilation in chloroplasts occurs via the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle. To determine the extent to which these enzymes contribute to the control of ammonia assimilation, a metabolic control analysis was performed on isolated barley (Hordeum vulgare L.) leaf chloroplasts. Pathway flux was measured polarographically as ammonium-plus-2-oxoglutarate-plus-glutamine-dependent O2 evolution in illuminated chloroplasts. Enzyme activity was modulated by titration with specific, irreversible inhibitors of GS (phosphinothricin) and GOGAT (azaserine). Flux control coefficients (CJ0E0) were determined (a) by differentiation of best-fit hyperbolic curves of the data sets (flux versus enzyme activity), and (b) from estimates of the deviation indices (D/[prime]E0). Both analyses gave similar values for the coefficients. The control coefficient for GS was relatively high and the value did not change significantly with changes in 2-oxoglutarate concentration (C/0E0 = 0.58 at 5 mM 2-oxoglutarate and 0.40 at 20 mM 2-oxoglutarate). The control coefficient for GOGAT decreased with decreasing glutamine concentrations, from 0.76 at 20 mM glutamine to 0.19 at 10 mM glutamine. Thus, at high concentrations of glutamine, GOGAT exerts a major control over flux with a significant contribution also from GS. At lower concentrations of glutamine, however, GOGAT exerts far less control over pathway flux. PMID:12232211

  16. Control of the ornithine cycle in Neurospora crassa by the mitochondrial membrane.

    PubMed Central

    Davis, R H; Ristow, J L

    1983-01-01

    In Neurospora crassa, the mitochondrial membrane separates ornithine used in arginine biosynthesis from ornithine used in the arginine degradative pathway in the cytosol. Ornithine easily exchanges across the mitochondrial membrane under conditions appropriate for synthesis of the immediate biosynthetic product, citrulline. Neither of the two mitochondrial enzymes required for the ornithine-to-citrulline conversion is feedback inhibitable in vitro. Nevertheless, when arginine is added to cells and cytosolic ornithine increases as arginine degradation begins, the rate of citrulline synthesis drops immediately to about 20% of normal (B. J. Bowman and R. H. Davis, Bacteriol. 130:285-291, 1977). We have studied this phenomenon in citrulline-accumulating strains carrying the arg-1 mutation. Citrulline accumulation is blocked when arginine is added to an arg-1 strain but not to an arg-1 strain carrying a mutation conferring insensitivity of intramitochondrial ornithine synthesis to arginine. Thus, ornithine is evidently unable to enter mitochondria in normal (feedback-sensitive) cells. Other experiments show that cytosolic ornithine enters mitochondria readily except when arginine or other basic amino acids are present at high levels in the cells. We conclude that in N. crassa, the mitochondrial membrane has evolved as a secondary site of feedback inhibition in arginine synthesis and that this prevents a wasteful cycling of catabolic ornithine back through the anabolic pathway. This is compared to the quite different mechanism by which the yeast Saccharomyces cerevisiae prevents a futile ornithine cycle. PMID:6222031

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. Walking cycle control for an active ankle prosthesis with one degree of freedom monitored from a personal computer.

    PubMed

    Cordero Andrés, Guzhñay; Arévalo Luis, Calle; Abad Julio, Zambrano

    2015-08-01

    This paper proposes a fuzzy control algorithm for human walking cycle of an active ankle prosthesis for people who have suffered amputation of the lower limb, the system has one degree of freedom in the sagittal plane. Also, a biomechanical analysis of foot and ankle is shown to define the phases of plantar support and swinging. The used actuator is an intelligent servomotor, Dynamixel MX-106T which has torque, current and position feedback, among others, allowing real-time telemetry of the prototype implemented in a microcontroller system. PMID:26737084

  3. 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. PMID:2349248

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

    PubMed

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

    2016-07-01

    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

  5. 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

  6. 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. PMID:23850226

  7. 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.

  8. TRF2 Controls Telomeric Nucleosome Organization in a Cell Cycle Phase-Dependent Manner

    PubMed Central

    Galati, Alessandra; Magdinier, Frédérique; Colasanti, Valentina; Bauwens, Serge; Pinte, Sébastien; Ricordy, Ruggero; Giraud-Panis, Marie-Josèphe; Pusch, Miriam Caroline; Savino, Maria

    2012-01-01

    Mammalian telomeres stabilize chromosome ends as a result of their assembly into a peculiar form of chromatin comprising a complex of non-histone proteins named shelterin. TRF2, one of the shelterin components, binds to the duplex part of telomeric DNA and is essential to fold the telomeric chromatin into a protective cap. Although most of the human telomeric DNA is organized into tightly spaced nucleosomes, their role in telomere protection and how they interplay with telomere-specific factors in telomere organization is still unclear. In this study we investigated whether TRF2 can regulate nucleosome assembly at telomeres. By means of chromatin immunoprecipitation (ChIP) and Micrococcal Nuclease (MNase) mapping assay, we found that the density of telomeric nucleosomes in human cells was inversely proportional to the dosage of TRF2 at telomeres. This effect was not observed in the G1 phase of the cell cycle but appeared coincident of late or post-replicative events. Moreover, we showed that TRF2 overexpression altered nucleosome spacing at telomeres increasing internucleosomal distance. By means of an in vitro nucleosome assembly system containing purified histones and remodeling factors, we reproduced the short nucleosome spacing found in telomeric chromatin. Importantly, when in vitro assembly was performed in the presence of purified TRF2, nucleosome spacing on a telomeric DNA template increased, in agreement with in vivo MNase mapping. Our results demonstrate that TRF2 negatively regulates the number of nucleosomes at human telomeres by a cell cycle-dependent mechanism that alters internucleosomal distance. These findings raise the intriguing possibility that telomere protection is mediated, at least in part, by the TRF2-dependent regulation of nucleosome organization. PMID:22536324

  9. Mechanisms Controlling the Annual Cycle of Precipitation in the Tropical Atlantic Sector in an Atmospheric GCM(.

    NASA Astrophysics Data System (ADS)

    Biasutti, M.; Battisti, D. S.; Sarachik, E. S.

    2004-12-01

    A set of AGCM experiments is used to study the annual cycle of precipitation in the region surrounding the tropical Atlantic Ocean. The experiments are designed to reveal the relative importance of insolation over land and the (uncoupled) SST on the annual cycle of precipitation over the tropical Atlantic Ocean, Africa, and the tropical Americas.SST variations impact the position of the maritime ITCZ by forcing the hydrostatic adjustment of the atmospheric boundary layer and changes in surface pressure and low-level convergence. The condensation heating released in the ITCZ contributes substantially to the surface circulation and the maintenance of the SST-induced ITCZ anomalies.The remote influence of SST is felt in equatorial coastal areas and the Sahel. The circulation driven by condensation heating in the maritime ITCZ extends to the coastal regions, thus communicating the SST signal onshore. Conversely, the Sahel responds to variations in SST through boundary layer processes that do not involve the maritime ITCZ. The atmospheric response to changes in subtropical SST is advected inland and forces changes in sea level pressure and low-level convergence across a large part of tropical Africa.The impact of local insolation on continental precipitation can be explained by balancing net energy input at the top of the atmospheric column with the export of energy by the divergent circulation that accompanies convection. Increased insolation reduces the stability of the atmosphere in the main continental convection centers, but not in monsoon regions.Insolation over land impacts the intensity of the maritime ITCZ via its influence on precipitation in Africa and South America. Reduced land precipitation induces the cooling of the Atlantic upper troposphere and the enhancement of convective available potential energy in the maritime ITCZ.


  10. SIAMESE, a gene controlling the endoreduplication cell cycle in Arabidopsis thaliana trichomes.

    PubMed

    Walker, J D; Oppenheimer, D G; Concienne, J; Larkin, J C

    2000-09-01

    Cell differentiation is generally tightly coordinated with the cell cycle, typically resulting in a nondividing cell with a unique differentiated morphology. The unicellular trichomes of Arabidopsis are a well-established model for the study of plant cell differentiation. Here, we describe a new genetic locus, SIAMESE (SIM), required for coordinating cell division and cell differentiation during the development of Arabidopsis trichomes (epidermal hairs). A recessive mutation in the sim locus on chromosome 5 results in clusters of adjacent trichomes that appeared to be morphologically identical 'twins'. Upon closer inspection, the sim mutant was found to produce multicellular trichomes in contrast to the unicellular trichomes produced by wild-type (WT) plants. Mutant trichomes consisting of up to 15 cells have been observed. Scanning electron microscopy of developing sim trichomes suggests that the cell divisions occur very early in the development of mutant trichomes. WT trichome nuclei continue to replicate their DNA after mitosis and cytokinesis have ceased, and as a consequence have a DNA content much greater than 2C. This phenomenon is known as endoreduplication. Individual nuclei of sim trichomes have a reduced level of endoreduplication relative to WT trichome nuclei. Endoreduplication is also reduced in dark-grown sim hypocotyls relative to WT, but not in light-grown hypocotyls. Double mutants of sim with either of two other mutants affecting endoreduplication, triptychon (try) and glabra3 (gl3) are consistent with a function for SIM in endoreduplication. SIM may function as a repressor of mitosis in the endoreduplication cell cycle. Additionally, the relatively normal morphology of multicellular sim trichomes indicates that trichome morphogenesis can occur relatively normally even when the trichome precursor cell continues to divide. The sim mutant phenotype also has implications for the evolution of multicellular trichomes. PMID:10952891

  11. 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.

  12. 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.

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

    PubMed Central

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

    2010-01-01

    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.—Mardaryev, A. N., Ahmed, M. I., Vlahov, N. V., Fessing, M. Y., Gill, J. H., Sharov, A. A., and Botchkareva, N. V. Micro-RNA-31 controls hair cycle-associated changes in gene expression programs of the skin and hair follicle. PMID:20522784

  14. Creation and control of a single coherent attosecond xuv pulse by few-cycle intense laser pulses

    NASA Astrophysics Data System (ADS)

    Carrera, Juan J.; Tong, X. M.; Chu, Shih-I.

    2006-08-01

    We present ab initio quantum and classical investigations on the production and control of a single attosecond pulse by using few-cycle intense laser pulses as the driving field. The high-harmonic-generation power spectrum is calculated by accurately and efficiently solving the time-dependent Schrödinger equation using the time-dependent generalized pseudospectral method. The time-frequency characteristics of the attosecond xuv pulse are analyzed in detail by means of the wavelet transform of the time-dependent induced dipole. To better understand the physical processes, we also perform classical trajectory simulation of the strong-field electron dynamics and electron returning energy map. We found that the quantum and classical results provide complementary and consistent information regarding the underlying mechanisms responsible for the production of the coherent attosecond pulse. For few-cycle (5fs) driving pulses, it is shown that the emission of the consecutive harmonics in the supercontinuum cutoff regime can be synchronized and locked in phase resulting in the production of a coherent attosecond pulse. Moreover, the time profile of the attosecond pulses can be controlled by tuning the carrier envelope phase.

  15. 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.

  16. Dynamics and control modeling of the closed-cycle gas turbine (GT-HTGR) power plant

    SciTech Connect

    Bardia, A.

    1980-02-01

    The simulation if presented for the 800-MW(e) two-loop GT-HTGR plant design with the REALY2 transient analysis computer code, and the modeling of control strategies called for by the inherently unique operational requirements of a multiple loop GT-HTGR is described. Plant control of the GT-HTGR is constrained by the nature of its power conversion loops (PCLs) in which the core cooling flow and the turbine flow are directly related and thus changes in flow affect core cooling as well as turbine power. Additionally, the high thermal inertia of the reactor core precludes rapid changes in the temperature of the turbine inlet flow.

  17. What controls the seasonal cycle of black carbon aerosols in India?

    NASA Astrophysics Data System (ADS)

    Kumar, Rajesh; Barth, M. C.; Pfister, G. G.; Nair, V. S.; Ghude, Sachin D.; Ojha, N.

    2015-08-01

    The seasonal variability of black carbon (BC) aerosols in India is studied using high resolution (10 km) BC simulations conducted using the Weather Research and Forecasting Model coupled with Chemistry. The model reproduces the observed seasonality of surface BC fairly well over most parts of India but fails to capture the seasonality in the Himalayas and deviates from the observed BC magnitude at several sites. The errors in modeled BC are attributed to uncertainties in BC emissions and their diurnal cycle, planetary boundary layer height underestimation, and aerosol processes. Model results show distinct but opposite seasonality of BC in the lower (LT) and free troposphere (FT) with BC showing winter maximum and summer minimum in the LT and vice versa in the FT. Our analysis shows that BC seasonality is not driven by seasonality of the anthropogenic emissions but by changes in the regional meteorology through weakening of the horizontal transport and strengthening of the vertical transport of BC during summertime compared to winter. BC in both the LT and FT comes mostly from anthropogenic emissions followed by biomass burning emissions except during winter when long-distant sources become more important in the FT. BC in the FT is significantly affected by anthropogenic emissions from all parts of India. The source-receptor relationship changes seasonally, but the regional transport remains a significant contributor to BC loadings in the LT of India, highlighting the necessity of considering nonlocal sources along with local emissions when designing strategies for mitigating BC impacts on air quality.

  18. Effects of multiple structural nonlinearities on limit cycle oscillation of missile control fin

    NASA Astrophysics Data System (ADS)

    Seo, Young-Jin; Lee, Seung-Jun; Bae, Jae-Sung; Lee, In

    2011-05-01

    Aeroelastic analyses are performed for a 2-D typical section model with multiple nonlinearities. The differences between a system with multiple nonlinearities in its pitch and plunge spring and a system with a single nonlinearity in its pitch are thoroughly investigated. The unsteady supersonic aerodynamic forces are calculated by the doublet point method (DPM). The iterative V-g method is used for a multiple-nonlinear aeroelastic analysis in the frequency domain and the freeplay nonlinearity is linearized using a describing function method. In the time domain, the DPM unsteady aerodynamic forces, which are based on a function of the reduced frequency, are approximated by the minimum state approximation method. Consequently, multiple structural nonlinearities in the 2-D typical wing section model are influenced by the pitch to plunge frequency ratio. This result is important in that it demonstrates that the flutter speed is closely connected with the frequency ratio, considering that both pitch and plunge nonlinearities result in a higher flutter speed boundary than a conventional aeroelastic system with only one pitch nonlinearity. Furthermore, the gap size of the freeplay affects the amplitude of the limit cycle oscillation (LCO) to gap size ratio.

  19. Apoptosis and modulation of cell cycle control by bile acids in human leukemia T cells.

    PubMed

    Fimognari, Carmela; Lenzi, Monia; Cantelli-Forti, Giorgio; Hrelia, Patrizia

    2009-08-01

    Depending on the nature of chemical structures, different bile acids exhibit distinct biological effects. Their therapeutic efficacy has been widely demonstrated in various liver diseases, suggesting that they might protect hepatocytes against common mechanisms of liver damage. Although it has been shown to prevent apoptotic cell death in certain cell lines, bile acids significantly inhibited cell growth and induced apoptosis in cancer cells. To better understand the pharmacological potential of bile acids in cancer cells, we investigated and compared the effects of deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and their taurine-derivatives [taurodeoxycholic acid (TDCA) and tauroursodeoxycholic acid (TUDCA), respectively] on the induction of apoptosis and inhibition of cell proliferation of a human T leukemia cell line (Jurkat cells). All the bile acids tested induced a delay in cell cycle progression. Moreover, DCA markedly increased the fraction of apoptotic cells. The effects of TDCA, UDCA, and TUDCA were different from those observed for DCA. Their primary effect was the induction of necrosis. These distinctive features suggest that the hydrophobic properties of DCA play a role in its cytotoxic potential and indicate that it is possible to create new drugs useful for cancer therapy from bile acid derivatives as lead compounds. PMID:19723064

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

    PubMed

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

    2014-01-01

    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. PMID:24787456

  1. Revisiting the 'Gadgil effect': do interguild fungal interactions control carbon cycling in forest soils?

    PubMed

    Fernandez, Christopher W; Kennedy, Peter G

    2016-03-01

    1382 I. 1382 II. 1383 III. 1383 IV. 1384 V. 1386 VI. 1387 VII. 1389 VIII. 1391 1391 References 1391 SUMMARY: In forest ecosystems, ectomycorrhizal and saprotrophic fungi play a central role in the breakdown of soil organic matter (SOM). Competition between these two fungal guilds has long been hypothesized to lead to suppression of decomposition rates, a phenomenon known as the 'Gadgil effect'. In this review, we examine the documentation, generality, and potential mechanisms involved in the 'Gadgil effect'. We find that the influence of ectomycorrhizal fungi on litter and SOM decomposition is much more variable than previously recognized. To explain the inconsistency in size and direction of the 'Gadgil effect', we argue that a better understanding of underlying mechanisms is required. We discuss the strengths and weaknesses of each of the primary mechanisms proposed to date and how using different experimental methods (trenching, girdling, microcosms), as well as considering different temporal and spatial scales, could influence the conclusions drawn about this phenomenon. Finally, we suggest that combining new research tools such as high-throughput sequencing with experiments utilizing natural environmental gradients will significantly deepen our understanding of the 'Gadgil effect' and its consequences on forest soil carbon and nutrient cycling. PMID:26365785

  2. 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.

  3. 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.

  4. System controls challenges of hypersonic combined-cycle engine powered vehicles

    NASA Technical Reports Server (NTRS)

    Morrison, Russell H.; Ianculescu, George D.

    1992-01-01

    Hypersonic aircraft with air-breathing engines have been described as the most complex and challenging air/space vehicle designs ever attempted. This is particularly true for aircraft designed to accelerate to orbital velocities. The propulsion system for the National Aerospace Plane will be an active factor in maintaining the aircraft on course. Typically addressed are the difficulties with the aerodynamic vehicle design and development, materials limitations and propulsion performance. The propulsion control system requires equal materials limitations and propulsion performance. The propulsion control system requires equal concern. Far more important than merely a subset of propulsion performance, the propulsion control system resides at the crossroads of trajectory optimization, engine static performance, and vehicle-engine configuration optimization. To date, solutions at these crossroads are multidisciplinary and generally lag behind the broader performance issues. Just how daunting these demands will be is suggested. A somewhat simplified treatment of the behavioral characteristics of hypersonic aircraft and the issues associated with their air-breathing propulsion control system design are presented.

  5. 78 FR 67223 - Proposed Guidance for Fuel Cycle Facility; Material Control and Accounting Plans and Completing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... for public comment the following draft NUREGs: NUREG-1280, Revision 2, ``Acceptable Standard Format... Material;'' NUREG-2159, ``Acceptable Standard Format and Content for the Material Control and Accounting (MC&A) Plan Required for Special Nuclear Material of Moderate Strategic Significance;''...

  6. 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...

  7. Life cycle of Uromyces salsolae, a candidate fungal biological control agent for Salsola tragus (Russian thistle)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salsola tragus (Russian thistle, Chenopodiaceae) is a major weed pest in the western United States. An isolate of the rust fungus Uromyces salsolae from the Yasensky Spit in Russia is currently under evaluation as a candidate for biological control of S. tragus in a Biosafety Level 3 (BL-3) contain...

  8. Linking the climatic and geochemical controls on global soil carbon cycling

    NASA Astrophysics Data System (ADS)

    Doetterl, Sebastian; Stevens, Antoine; Six, Johan; Merckx, Roel; Van Oost, Kristof; Casanova Pinto, Manuel; Casanova-Katny, Angélica; Muñoz, Cristina; Boudin, Mathieu; Zagal Venegas, Erick; Boeckx, Pascal

    2015-04-01

    Climatic and geochemical parameters are regarded as the primary controls for soil organic carbon (SOC) storage and turnover. However, due to the difference in scale between climate and geochemical-related soil research, the interaction of these key factors for SOC dynamics have rarely been assessed. Across a large geochemical and climatic transect in similar biomes in Chile and the Antarctic Peninsula we show how abiotic geochemical soil features describing soil mineralogy and weathering pose a direct control on SOC stocks, concentration and turnover and are central to explaining soil C dynamics at larger scales. Precipitation and temperature had an only indirect control by regulating geochemistry. Soils with high SOC content have low specific potential CO2 respiration rates, but a large fraction of SOC that is stabilized via organo-mineral interactions. The opposite was observed for soils with low SOC content. The observed differences for topsoil SOC stocks along this transect of similar biomes but differing geo-climatic site conditions are of the same magnitude as differences observed for topsoil SOC stocks across all major global biomes. Using precipitation and a set of abiotic geochemical parameters describing soil mineralogy and weathering status led to predictions of high accuracy (R2 0.53-0.94) for different C response variables. Partial correlation analyses revealed that the strength of the correlation between climatic predictors and SOC response variables decreased by 51 - 83% when controlling for geochemical predictors. In contrast, controlling for climatic variables did not result in a strong decrease in the strength of the correlations of between most geochemical variables and SOC response variables. In summary, geochemical parameters describing soil mineralogy and weathering were found to be essential for accurate predictions of SOC stocks and potential CO2 respiration, while climatic factors were of minor importance as a direct control, but are

  9. Life cycle and control of the forest bug Pentatoma rufipes L. in organically managed pear orchards.

    PubMed

    Peusens, G; Beliën, T

    2012-01-01

    In Belgian pear production growers may encounter major economic problems when fruit becomes damaged by bugs. One of the major pests belongs to the stink bugs, Pentatoma rufipes L. (Heteroptera, Pentatomidae) which feeds by piercing into buds, flowers and fruit. To study the population dynamics of this species it was monitored in organic pear orchards by the beating tray method. Results revealed their univoltine life cycle and their presence within the orchard during the entire year. They overwinter in the second nymphal stage and become active in March/April. After 3 moultings adulthood is reached during May/June. In summer mating takes place and eggs are laid at the underside of the leaves of the fruit trees. By the end of August the eggs hatch and the first young nymphs appear. At first they aggregate but when they have moulted into the next stage dispersal takes place (September) and by October they search for hiding places on the trees to hibernate. As damage is done before and after blossom the application of an insecticide has to be well defined and timed. Therefore the efficacy of spinosad and natural pyrethrum, applied once or twice before and/or after bloom, was compared in a field trial. Data indicated that a single application of spinosad after bloom and a double application of spinosad or pyrethrum (before and after bloom) reduced the number of bugs with 83.3%. Damage to the crop was the lowest (4.5%) when spinosad was applied twice but no statistical difference with both other applications was found. PMID:23885435

  10. 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

  11. 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

  12. Nutrient cycling.

    PubMed

    Bormann, F H; Likens, G E

    1967-01-27

    The small-watershed approach to problems of nutrient cycling has these advantages. (i) The small watershed is a natural unit of suitable size for intensive study of nutrient cycling at the ecosystem level. (ii) It provides a means of reducing to a minimum, or virtually eliminating, the effect of the difficult-to-measure variables of geologic input and nutrient losses in deep seepage. Control of these variables makes possible accurate measurement of nutrient input and output (erosion) and therefore establishes the relationship of the smaller ecosystem to the larger biospheric cycles. (iii) The small-watershed approach provides a method whereby such important parameters as nutrient release from minerals (weathering) and annual nutrient budgets may be calculated. (iv) It provides a means of studying the interrelationships between the biota and the hydrologic cycle, various nutrient cycles, and energy flow in a single system. (v) Finally, with the small-watershed system we can test the effect of various land-management practices or environmental pollutants on nutrient cycling in natural systems. PMID:17737551

  13. 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

  14. 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

  15. 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.

  16. 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

  17. Expression of chloroplast protein genes during the cell cycle of Chlamydomonas reinhardtii: evidence for transcriptional and translocational control

    SciTech Connect

    Herrin, D.L.

    1986-01-01

    Chlamydomonas reinhardtii cells, growing synchronously under a repeating 12 h light:12 h dark cycle, were used to investigate the synthesis and regulation of chloroplast proteins. The cells accumulate chlorophyll, the major thylakoid membrane proteins, and ribulose-1,5-bisphosphate carboxylase (RuBPCase) during the light (G1) period of the cell cycle. Pulse-labeling in vivo with (/sup 3/H)arginine, and analysis of the protein synthetic capacity of thylakoid-bound polysomes in vitro, shows that these proteins are synthesized de novo during the light. Specific antibody and cloned DNA probes were obtained and used to estimate translatable and/or steady-state mRNA levels for light-harvesting (LHCII) and reaction center (D-1 and D-2) polypeptides of photosystem II, a light-harvesting polypeptide of photosystem I (LHCI), and the large (LS) and small (SS) subunits of RuBPCase. Levels of mRNA for the nuclear-encoded LHCI, LHCII and SS correlated with the synthesis of these polypeptides in vivo; they were higher in the light period and several-folded lower or absent during the dark period. The results suggest that synthesis of nuclear-encoded chloroplast proteins are regulated primarily by the level of mRNA. In contrast, regulation of chloroplast-encoded genes is achieved by controlling the translation of mRNA that is constitutively present, and by transcriptional mechanisms during light induction.

  18. A role for Hsp90 in cell cycle control: Wee1 tyrosine kinase activity requires interaction with Hsp90.

    PubMed Central

    Aligue, R; Akhavan-Niak, H; Russell, P

    1994-01-01

    Wee1 protein kinase regulates the length of G2 phase by carrying out the inhibitory tyrosyl phosphorylation of Cdc2-cyclin B kinase. Mutations were isolated that suppressed the G2 cell cycle arrest caused by overproduction of Wee1. One class of swo (suppressor of wee1 overproduction) mutation, exemplified by swo1-26, also caused a temperature sensitive lethal phenotype in a wee1+ background. The swo1+ gene encodes a member of the Hsp90 family of stress proteins. Swo1 is essential for viability at all temperatures. Swo1 coimmunoprecipitates with Wee1, showing that the two proteins interact. The swo1-26 mutant undergoes premature mitosis when grown at a semi-permissive temperature. These data strongly indicate that formation of active Wee1 tyrosine kinase requires interaction with Swo1, perhaps in a manner analogous to the previously demonstrated interaction between Hsp90 and v-src tyrosine kinase. These observations demonstrate a unexpected role for Hsp90 in cell cycle control. Images PMID:7813446

  19. Galectin-4 Controls Intestinal Inflammation by Selective Regulation of Peripheral and Mucosal T Cell Apoptosis and Cell Cycle

    PubMed Central

    Paclik, Daniela; Danese, Silvio; Berndt, Uta; Wiedenmann, Bertram; Dignass, Axel; Sturm, Andreas

    2008-01-01

    Galectin-4 is a carbohydrate-binding protein belonging to the galectin family. Here we provide novel evidence that galectin-4 is selectively expressed and secreted by intestinal epithelial cells and binds potently to activated peripheral and mucosal lamina propria T-cells at the CD3 epitope. The carbohydrate-dependent binding of galectin-4 at the CD3 epitope is fully functional and inhibited T cell activation, cycling and expansion. Galectin-4 induced apoptosis of activated peripheral and mucosal lamina propria T cells via calpain-, but not caspase-dependent, pathways. Providing further evidence for its important role in regulating T cell function, galectin-4 blockade by antisense oligonucleotides reduced TNF-alpha inhibitor induced T cell death. Furthermore, in T cells, galectin-4 reduced pro-inflammatory cytokine secretion including IL-17. In a model of experimental colitis, galectin-4 ameliorated mucosal inflammation, induced apoptosis of mucosal T-cells and decreased the secretion of pro-inflammatory cytokines. Our results show that galectin-4 plays a unique role in the intestine and assign a novel role of this protein in controlling intestinal inflammation by a selective induction of T cell apoptosis and cell cycle restriction. Conclusively, after defining its biological role, we propose Galectin-4 is a novel anti-inflammatory agent that could be therapeutically effective in diseases with a disturbed T cell expansion and apoptosis such as inflammatory bowel disease. PMID:18612433

  20. 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

  1. 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

  2. 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.

  3. Changes in the composition of brain interstitial ions control the sleep-wake cycle.

    PubMed

    Ding, Fengfei; O'Donnell, John; Xu, Qiwu; Kang, Ning; Goldman, Nanna; Nedergaard, Maiken

    2016-04-29

    Wakefulness is driven by the widespread release of neuromodulators by the ascending arousal system. Yet, it is unclear how these substances orchestrate state-dependent, global changes in neuronal activity. Here, we show that neuromodulators induce increases in the extracellular K(+) concentration ([K(+)]e) in cortical slices electrically silenced by tetrodotoxin. In vivo, arousal was linked to AMPA receptor-independent elevations of [K(+)]e concomitant with decreases in [Ca(2+)]e, [Mg(2+)]e, [H(+)]e, and the extracellular volume. Opposite, natural sleep and anesthesia reduced [K(+)]e while increasing [Ca(2+)]e, [Mg(2+)]e, and [H(+)]e as well as the extracellular volume. Local cortical activity of sleeping mice could be readily converted to the stereotypical electroencephalography pattern of wakefulness by simply imposing a change in the extracellular ion composition. Thus, extracellular ions control the state-dependent patterns of neural activity. PMID:27126038

  4. 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. PMID:25146289

  5. 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.

  6. 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

  7. Ocean biology could control atmospheric δ13C during glacial-interglacial cycle

    NASA Astrophysics Data System (ADS)

    Brovkin, Victor; Hofmann, Matthias; Bendtsen, Jørgen; Ganopolski, Andrey

    2002-05-01

    Estimates of changes in the global carbon budget are often based on the assumption that the terrestrial biosphere controls the isotopic composition of atmospheric CO2 since terrestrial plants discriminate against the 13C isotope during photosynthesis. However, this method disregards the influence of 13C fractionation by the marine biota. Here an interpretation of the glacial-interglacial shifts in the atmospheric CO2 concentration and δ13CO2 measured in the Taylor Dome ice core [Smith et al., 1999] is given by accounting for possible changes in the ocean biology based on sensitivity simulations undertaken with the intermediate complexity model CLIMBER-2. With a combined scenario of enhanced biological and solubility pumps, the model simulates glacial atmospheric CO2 and δ13CO2 similar to those inferred from the ice core. The simulations reveal that a strengthening of the oceanic biological carbon pump considerably affects the atmospheric δ13CO2.

  8. 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.

  9. 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.

  10. Synchronous cycles of domestic dog rabies in sub-Saharan Africa and the impact of control efforts.

    PubMed

    Hampson, Katie; Dushoff, Jonathan; Bingham, John; Brückner, Gideon; Ali, Y H; Dobson, Andy

    2007-05-01

    Rabies is a fatal neurological pathogen that is a persistent problem throughout the developing world where it is spread primarily by domestic dogs. Although the disease has been extensively studied in wildlife populations in Europe and North America, the dynamics of rabies in domestic dog populations has been almost entirely neglected. Here, we demonstrate that rabies epidemics in southern and eastern Africa cycle with a period of 3-6 years and show significant synchrony across the region. The observed period is shorter than predictions based on epidemiological parameters for rabies in domestic dogs. We find evidence that rabies prevention measures, including vaccination, are affected by disease prevalence and show that a simple model with intervention responses can capture observed disease periodicity and host dynamics. We suggest that movement of infectious or latent animals combined with coordinated control responses may be important in coupling populations and generating synchrony at the continental scale. These findings have important implications for rabies prediction and control: large-scale synchrony and the importance of intervention responses suggest that control of canine rabies in Africa will require sustained efforts coordinated across political boundaries. PMID:17452645

  11. 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

  12. 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

  13. 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.

  14. Hydrological control on carbon export and cycling in three subarctic micro-catchments

    NASA Astrophysics Data System (ADS)

    Ohlanders, N.; Hodson, A. J.; Phoenix, G.

    2011-12-01

    Future climatic change in the Scandinavian subarctic region will likely affect export of organic carbon and inorganic uptake of atmospheric carbon dioxide in weathering reactions. These two processes are both likely to increase in magnitude as a response to increasing precipitation. Whereas the former is linked to processes resulting in a positive feedback to atmospheric CO2, the latter causes sequestration of atmospheric CO2 and therefore provides a negative feedback to global warming. Links between variables such as soil maturity, flow routing, water residence time, carbon export and weathering rates need to be further established in order to evaluate the effects of future climatic change on the hydrology and carbon economy of subarctic catchments. Further, little attention has been given to the long-term development of mentioned hydrologic processes. We present here, detailed water and nutrient mass balances for three subarctic micro-catchments (<1 km2) located along a landscape maturity gradient in the Abisko area in northern Sweden. Stream- and soil water, precipitation and snowpacks were sampled frequently. Annual nutrient yields, flowpath variability, organic content of snowpacks and response in water quality to snowmelt-induced runoff events were assessed within these catchments. Along the landscape maturity gradient studied, there was a large variability in flowpath control on solute composition and yields. This variabilty was characterised by an increasing importance of a groundwater flowpath towards the more mature site, resulting in the highest concentration and yields of weathering product at this site. Long term control on carbon fluxes via hydrologic flowpaths might therefore differ in subarctic Scandinavia compare to the Glacier Bay area in Alaska, for which the importance of groundwater has been shown to decrease with landscape maturity. This is due to the geomorphological setting of these contrasting landscapes; the time/space-substitution and

  15. 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

  16. 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.

  17. 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.

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

    DOEpatents

    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).

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

    PubMed

    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

  20. 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

  1. 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

  2. Crystal-plastic deformation and recrystallization of peridotite controlled by the seismic cycle

    NASA Astrophysics Data System (ADS)

    Matysiak, Agnes K.; Trepmann, Claudia A.

    2012-03-01

    Deformed peridotites from the Balmuccia complex, Northern Italy, have been investigated by light and electron microscopy (SEM/EBSD, TEM). The peridotites show a heterogeneous and partly recrystallized microfabric associated with cataclastic shear zones. Intracrystalline deformation microstructures (undulatory extinction, crinkly deformation lamellae, deformation bands, kink bands) and recrystallized grains along intragranular zones in large original grains record a sequence with an initial stage of inhomogeneous glide-controlled deformation in the low-temperature plasticity regime associated with brittle deformation and a subsequent stage of recovery and recrystallization. The microstructural evidence of deformation of olivine in the low-temperature field indicates high stresses on the order of several hundred MPa and accordingly high strain rates. Subsequent recovery and recrystallization requires decreasing stresses and strain rates, as there is no evidence for a complex thermal history with increasing temperatures. A locally occurring foam structure in aggregates of recrystallized olivine indicates grain growth at very low differential stresses at a late stage. Such a stress history with transiently high and then decaying stresses is characteristic for coseismic deformation and postseismic creep just below the base of the seismogenic zone. The associated occurrence of pseudotachylytes and microstructures generated by crystal-plastic mechanisms is explained by semi-brittle behavior at transient high stresses and strain rates during coseismic loading at depths, where during postseismic relaxation and in interseismic periods the rocks are behaving by crystal-plastic flow. The consideration of high-stress deformation and subsequent recrystallization processes at decaying stresses in peridotites is especially relevant for earthquake-driven deformation in the mantle.

  3. 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

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. Impact of sideways and bottom-up control factors on bacterial community succession over a tidal cycle.

    PubMed

    Chauhan, Ashvini; Cherrier, Jennifer; Williams, Henry N

    2009-03-17

    In aquatic systems, bacterial community succession is a function of top-down and bottom-up factors, but little information exists on "sideways" controls, such as bacterial predation by Bdellovibrio-like organisms (BLOs), which likely impacts nutrient cycling within the microbial loop and eventual export to higher trophic groups. Here we report transient response of estuarine microbiota and BLO spp. to tidal-associated dissolved organic matter supply in a river-dominated estuary, Apalachicola Bay, Florida. Both dissolved organic carbon and dissolved organic nitrogen concentrations oscillated over the course of the tidal cycle with relatively higher concentrations observed at low tide. Concurrent with the shift in dissolved organic matter (DOM) supply at low tide, a synchronous increase in numbers of bacteria and predatorial BLOs were observed. PCR-restriction fragment length polymorphism of small subunit rDNA, cloning, and sequence analyses revealed distinct shifts such that, at low tide, significantly higher phylotype abundances were observed from gamma-Proteobacteria, delta-Proteobacteria, Bacteroidetes, and high G+C gram-positive bacteria. Conversely, diversity of alpha-Proteobacteria, beta-Proteobacteria, and Chlamydiales-Verrucomicrobia group increased at high tides. To identify metabolically active BLO guilds, tidal microcosms were spiked with six (13)C-labeled bacteria as potential prey and studied using an adaptation of stable isotope probing. At low tide, representative of higher DOM and increased prey but lower salinity, BLO community also shifted such that mesohaline clusters I and VI were more active; with an increased salinity at high tide, halotolerant clusters III, V, and X were predominant. Eventually, (13)C label was identified from higher micropredators, indicating that trophic interactions within the estuarine microbial food web are potentially far more complex than previously thought. PMID:19251645

  11. 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.

  12. 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.

  13. Strain-Controlled Low-Cycle Fatigue Behavior of Friction Stir-Welded AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Yang, J.; Ni, D. R.; Wang, D.; Xiao, B. L.; Ma, Z. Y.

    2014-04-01

    Strain-controlled low-cycle fatigue (LCF) behavior of friction stir-welded (FSW) AZ31 joints, produced at rotation rates of 800 and 3500 rpm, was studied. The joints exhibited symmetric hysteresis loops, whereas asymmetric loops were observed for the parent material (PM). The fatigue resistance of the FSW joints was slightly improved as the rotation rate increased, and both the FSW joints possessed a fatigue life similar to that of the PM at the low strain amplitude of 0.1 pct. The obtained fatigue data for the PM and FSW joints can be well described using the Coffin-Manson and Basquin's relationships. For the FSW joints, during LCF deformation, the twinning originated from the nugget zone (NZ)/thermomechanically affected zone (TMAZ) boundary and then propagated to the NZ interior. This was attributed to different textures in these regions: the center of the NZ exhibited a hard orientation, whereas a soft orientation was observed in the region around the NZ/TMAZ boundary. The fatigue cracks initiated at the bottom of the joints and propagated along the NZ/TMAZ boundary or the NZ adjacent to the NZ/TMAZ boundary.

  14. 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

  15. Murine cerebellar neurons express a novel gene encoding a protein related to cell cycle control and cell fate determination proteins.

    PubMed

    Taoka, M; Isobe, T; Okuyama, T; Watanabe, M; Kondo, H; Yamakawa, Y; Ozawa, F; Hishinuma, F; Kubota, M; Minegishi, A

    1994-04-01

    We cloned cDNAs of a novel protein (designated V-1) that has been identified from among the developmentally regulated proteins in the rat cerebellum. Protein sequencing analysis (Taoka, M., Yamakuni, T., Song, S.-Y., Yamakawa, Y., Seta, K., Okuyama, T., and Isobe, T. (1992) Eur. J. Biochem. 207, 615-620) and cDNA sequence analysis revealed that the V-1 protein consists of 117 amino acids and contains 2.5 contiguous repeats of the cdc10/SWI6 motif, which was originally found in the products of the cell cycle control genes of yeasts and the cell fate determination genes in Drosophila and Caenorhabditis elegans. In situ hybridization histochemistry revealed that the expression of the V-1 gene is transiently increased in postmigratory granule cells during postnatal rat cerebellar development and thereafter is markedly suppressed, whereas Purkinje cells constitutively express V-1 mRNA. In contrast, cerebellar granule cells of the staggerer mutant mouse continue to express the V-1 gene even when the granule cells of the normal mouse have ceased to express the V-1 gene, suggesting that the expression of the V-1 gene in granule cells is regulated through the interaction with Purkinje cells. On the basis of these results, we postulate that the V-1 protein has a potential role in the differentiation of granule cells. PMID:8144589

  16. The multiple roles of cyclin E1 in controlling cell cycle progression and cellular morphology of Trypanosoma brucei.

    PubMed

    Gourguechon, Stéphane; Savich, Jason M; Wang, Ching C

    2007-05-11

    Regulation of eukaryotic cell cycle progression requires sequential activation and inactivation of cyclin-dependent kinases. Previous RNA interference (RNAi) experiments in Trypanosoma brucei indicated that cyclin E1, cdc2-related kinase (CRK)1 and CRK2 are involved in regulating G1/S transition, whereas cyclin B2 and CRK3 play a pivotal role in controlling the G2/M checkpoint. To search for potential interactions between the other cyclins and CRKs that may not have been revealed by the RNAi assays, we used the yeast two-hybrid system and an in vitro glutathione-S-transferase pulldown assay and observed interactions between cyclin E1 and CRK1, CRK2 and CRK3. Cyclins E1-E4 are homologues of yeast Pho80 cyclin. But yeast complementation assays indicated that none of them possesses a Pho80-like function. Analysis of cyclin E1+CRK1 and cyclin E1+CRK2 double knockdowns in the procyclic form of T. brucei indicated that the cells were arrested more extensively in the G1 phase beyond the cumulative effect of individual knockdowns. But BrdU incorporation was impaired significantly only in cyclin E1+CRK1-depleted cells, whereas a higher percentage of cyclin E1+CRK2 knockdown cells assumed a grossly elongated posterior end morphology. A double knockdown of cyclin E1 and CRK3 arrested cells in G2/M much more efficiently than if only CRK3 was depleted. Taken together, these data suggest multiple functions of cyclin E1: it forms a complex with CRK1 in promoting G1/S phase transition; it forms a complex with CRK2 in controlling the posterior morphogenesis during G1/S transition; and it forms a complex with CRK3 in promoting passage across the G2/M checkpoint in the trypanosome. PMID:17376478

  17. THE MULTIPLE ROLES OF CYCLIN E1 IN CONTROLLING CELL CYCLE PROGRESSION AND CELLULAR MORPHOLOGY OF TRYPANOSOMA BRUCEI

    PubMed Central

    Gourguechon, Stéphane; Savich, Jason M.; Wang, Ching C.

    2009-01-01

    SUMMARY Regulation of eukaryotic cell cycle progression requires sequential activation and inactivation of cyclin-dependent kinases. Previous RNA interference (RNAi) experiments in Trypanosoma brucei indicated that cyclin E1, cdc2-related kinase (CRK)1 and CRK2 are involved in regulating G1/S transition, whereas cyclin B2 and CRK3 play a pivotal role in controlling the G2/M checkpoint. To search for potential interactions between the other cyclins and CRKs that may not have been revealed by the RNAi assays, we used the yeast two-hybrid system and an in vitro GST pulldown assay and observed interactions between cyclin E1 and CRK1, CRK2 and CRK3. Cyclins E1-E4 are homologues of yeast Pho80 cyclin. But yeast complementation assays indicated that none of them possesses a Pho80-like function. Analysis of cyclin E1+CRK1 and cyclin E1+CRK2 double knockdowns in the procyclic form of T. brucei indicated that the cells were arrested more extensively in the G1 phase beyond the cumulative effect of individual knockdowns. But BrdU incorporation was significantly impaired only in cyclin E1+CRK1 depleted cells, whereas a higher percentage of cyclin E1+CRK2 knockdown cells assumed a grossly elongated posterior end morphology. A double knockdown of cyclin E1 and CRK3 arrested cells in G2/M much more efficiently than if CRK3 was depleted alone. Taken together, these data suggest multiple functions of cyclin E1. It forms a complex with CRK1 in promoting G1/S phase transition, with CRK2 in controlling the posterior morphogenesis during G1/S transition and with CRK3 in promoting passage across the G2/M checkpoint in the trypanosome. PMID:17376478

  18. 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.

  19. 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. PMID:26282612

  20. [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

  1. 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…

  2. 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

  3. 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.

  4. Evaluation of Suitable Internal Control Genes for RT-qPCR in Yak Mammary Tissue during the Lactation Cycle

    PubMed Central

    Jiang, MingFeng; Lee, Jung Nam; Bionaz, Massimo; Deng, Xiao Yu; Wang, Yong

    2016-01-01

    The yak is primarily found throughout the Tibetan high plateau and the surrounding mountainous area of south central Asia; among its others attributes, its milk is very important for the local population. A key concern in the field of yak research is the better understanding of which genes control the production and composition of milk. The most accurate and sensitive method for gene expression analysis is quantitative reverse transcription polymerase chain reaction (RT-qPCR). It is essential for reliable RT-qPCR to be able to the normalize the data using internal control genes (ICGs). However, it is critical to assess the reliability of the normalization by testing multiple ICGs. Our objective was to uncover a reliable normalization for RT-qPCR data obtained from yak mammary tissue during the lactation cycle. We assessed the reliability of 10 ICGs (ACTB, EIF6, GAPDH, LRP10, MRPL39, MRPS15, MTG1, RPS8, RPS23, and UXT) using geNorm. The analysis revealed that all of the tested ICGs can be considered to be reliable, but the use of the 6 most stable ICGs should be applied to yield a reliable normalization factor (NF). We compared the results of 3 target genes (CSN1S1, ESR1, and MYC) normalized using 6, 3, or 1 of the best ICGs. We did not observe overall differences between the 3 normalization strategies with the exception of 1 time point in MYC. The use of only a single ICG is not recommended; thus, we concluded that the calculation of the NF using the 3 best ICGs, MRPS15, RPS23, and UXT, is a reliable normalization strategy for RT-qPCR data obtained from yak mammary tissue during pregnancy and lactation. A dilution effect of the ICGs due to a large increase in the mRNA of abundantly expressed genes in bovine and porcine mammary tissue during the lactation cycle was previously observed. To test for the presence of a dilution effect in our study, we evaluated the pattern of non-normalized RT-qPCR data of ICGs from pregnancy to lactation and compared them with the

  5. Evaluation of Suitable Internal Control Genes for RT-qPCR in Yak Mammary Tissue during the Lactation Cycle.

    PubMed

    Jiang, MingFeng; Lee, Jung Nam; Bionaz, Massimo; Deng, Xiao Yu; Wang, Yong

    2016-01-01

    The yak is primarily found throughout the Tibetan high plateau and the surrounding mountainous area of south central Asia; among its others attributes, its milk is very important for the local population. A key concern in the field of yak research is the better understanding of which genes control the production and composition of milk. The most accurate and sensitive method for gene expression analysis is quantitative reverse transcription polymerase chain reaction (RT-qPCR). It is essential for reliable RT-qPCR to be able to the normalize the data using internal control genes (ICGs). However, it is critical to assess the reliability of the normalization by testing multiple ICGs. Our objective was to uncover a reliable normalization for RT-qPCR data obtained from yak mammary tissue during the lactation cycle. We assessed the reliability of 10 ICGs (ACTB, EIF6, GAPDH, LRP10, MRPL39, MRPS15, MTG1, RPS8, RPS23, and UXT) using geNorm. The analysis revealed that all of the tested ICGs can be considered to be reliable, but the use of the 6 most stable ICGs should be applied to yield a reliable normalization factor (NF). We compared the results of 3 target genes (CSN1S1, ESR1, and MYC) normalized using 6, 3, or 1 of the best ICGs. We did not observe overall differences between the 3 normalization strategies with the exception of 1 time point in MYC. The use of only a single ICG is not recommended; thus, we concluded that the calculation of the NF using the 3 best ICGs, MRPS15, RPS23, and UXT, is a reliable normalization strategy for RT-qPCR data obtained from yak mammary tissue during pregnancy and lactation. A dilution effect of the ICGs due to a large increase in the mRNA of abundantly expressed genes in bovine and porcine mammary tissue during the lactation cycle was previously observed. To test for the presence of a dilution effect in our study, we evaluated the pattern of non-normalized RT-qPCR data of ICGs from pregnancy to lactation and compared them with the

  6. The STIM1-Orai1 pathway of store-operated Ca2+ entry controls the checkpoint in cell cycle G1/S transition

    PubMed Central

    Chen, Yun-Wen; Chen, Yih-Fung; Chen, Ying-Ting; Chiu, Wen-Tai; Shen, Meng-Ru

    2016-01-01

    Ca2+ signaling is important to trigger the cell cycle progression, while it remains elusive in the regulatory mechanisms. Here we show that store-operated Ca2+ entry (SOCE), mediated by the interaction between STIM1 (an endoplasmic reticulum Ca2+ sensor) and Orai1 (a cell membrane pore structure), controls the specific checkpoint of cell cycle. The fluctuating SOCE activity during cell cycle progression is universal in different cell types, in which SOCE is upregulated in G1/S transition and downregulated from S to G2/M transition. Pharmacological or siRNA inhibition of STIM1-Orai1 pathway of SOCE inhibits the phosphorylation of CDK2 and upregulates the expression of cyclin E, resulting in autophagy accompanied with cell cycle arrest in G1/S transition. The subsequently transient expression of STIM1 cDNA in STIM1−/− MEF rescues the phosphorylation and nuclear translocation of CDK2, suggesting that STIM1-mediated SOCE activation directly regulates CDK2 activity. Opposite to the important role of SOCE in controlling G1/S transition, the downregulated SOCE is a passive phenomenon from S to G2/M transition. This study uncovers SOCE-mediated Ca2+ microdomain that is the molecular basis for the Ca2+ sensitivity controlling G1/S transition. PMID:26917047

  7. Two modeling approaches for quantifying hydrologic and biologic controls on large-scale nitrogen cycling, Upper Rio Grande, NM

    NASA Astrophysics Data System (ADS)

    Oelsner, G. P.; Brooks, P. D.; Hogan, J. F.; Meixner, T.; Tidwell, V.; Roach, J. D.

    2007-12-01

    Variations in nutrient concentrations can be caused by both abiotic changes in hydrology and biotic processes. Most process-level studies of nutrient cycling are conducted in small catchment systems and at points on large river systems. Relatively less understanding has been developed on how biotic and abiotic processes influence large-scale nutrient concentrations and variability in large river systems. To address this issue, we performed biannual synoptic chemical sampling along a 640 km reach of the Upper Rio Grande for five years to determine the large-scale patterns in dissolved carbon and nitrogen concentrations and then used two different and simple models to evaluate the abiotic and biotic processes that generate the observed large-scale patterns. First, we used a Cl mixing model, validated with Br to quantify the effects of evapoconcentration, tributaries, and point sources on dissolved nitrogen and carbon concentrations. Ratios of observed to predicted concentrations close to 1 suggest that abiotic hydrologic processes are the dominant controls on concentrations while ratios departing from 1 indicate that biological processes are important controls. Our conservative mixing model generally captured patterns in DOC concentrations, suggesting minimal, net biological processing. In contrast, both nitrate and TDN concentrations were altered biogeochemically in all reaches. In areas where observed and predicted values differed, the spatial variability of river characteristics was more strongly correlated to relative nutrient retention than seasonal or inter-annual discharge variability. Second, we used an integrated surface water - groundwater dynamic simulation model to evaluate the agricultural conveyance and riparian systems as potential nitrogen removal locations. Under conservative behavior, modeled nitrate concentrations were higher than observed in the groundwater, river, and conveyance channels. We calibrated the model using denitrification in the

  8. 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

  9. A power and load priority control concept as applied to a Brayton cycle turbo-electric generator.

    NASA Technical Reports Server (NTRS)

    Kelsey, E. L.; Young, R. N.

    1972-01-01

    This paper describes a system to regulate the speed and power output of a Brayton Cycle Power System under varying load. A typical user load profile is applied and a simple load priority and parasitic load is used for system regulation. Power storage is provided by batteries with charge and discharge converters to demonstrate support capability. The breadboard system is tested with the Brayton Cycle Demonstrator at the National Aeronautics and Space Administration, Manned Space Craft Center, Houston, Texas.

  10. Responses of genes involved in cell cycle control to diverse DNA damaging chemicals in human lung adenocarcinoma A549 cells

    PubMed Central

    Zhu, Huijun; Smith, Catherine; Ansah, Charles; Gooderham, Nigel J

    2005-01-01

    Background Many anticancer agents and carcinogens are DNA damaging chemicals and exposure to such chemicals results in the deregulation of cell cycle progression. The molecular mechanisms of DNA damage-induced cell cycle alteration are not well understood. We have studied the effects of etoposide (an anticancer agent), cryptolepine (CLP, a cytotoxic alkaloid), benzo [a]pyrene (BaP, a carcinogenic polycyclic aromatic hydrocarbon) and 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP, a cooked-meat derived carcinogen) on the expression of cell cycle regulatory genes to understand the molecular mechanisms of the cell cycle disturbance. Results A549 cells were treated with DMSO or chemicals for up to 72 h and periodically sampled for cell cycle analysis, mRNA and protein expression. DMSO treated cells showed a dominant G1 peak in cell cycle at all times examined. Etoposide and CLP both induced G2/M phase arrest yet the former altered the expression of genes functioning at multiple phases, whilst the latter was more effective in inhibiting the expression of genes in G2-M transition. Both etoposide and CLP induced an accumulation of p53 protein and upregulation of p53 transcriptional target genes. Neither BaP nor PhIP had substantial phase-specific cell cycle effect, however, they induced distinctive changes in gene expression. BaP upregulated the expression of CYP1B1 at 6–24 h and downregulated many cell cycle regulatory genes at 48–72 h. By contrast, PhIP increased the expression of many cell cycle regulatory genes. Changes in the expression of key mRNAs were confirmed at protein level. Conclusion Our experiments show that DNA damaging agents with different mechanisms of action induced distinctive changes in the expression pattern of a panel of cell cycle regulatory genes. We suggest that examining the genomic response to chemical exposure provides an exceptional opportunity to understand the molecular mechanism involved in cellular response to toxicants. PMID

  11. Catabolite Control Protein E (CcpE) Is a LysR-type Transcriptional Regulator of Tricarboxylic Acid Cycle Activity in Staphylococcus aureus*

    PubMed Central

    Hartmann, Torsten; Zhang, Bo; Baronian, Grégory; Schulthess, Bettina; Homerova, Dagmar; Grubmüller, Stephanie; Kutzner, Erika; Gaupp, Rosmarie; Bertram, Ralph; Powers, Robert; Eisenreich, Wolfgang; Kormanec, Jan; Herrmann, Mathias; Molle, Virginie; Somerville, Greg A.; Bischoff, Markus

    2013-01-01

    The tricarboxylic acid cycle (TCA cycle) is a central metabolic pathway that provides energy, reducing potential, and biosynthetic intermediates. In Staphylococcus aureus, TCA cycle activity is controlled by several regulators (e.g. CcpA, CodY, and RpiRc) in response to the availability of sugars, amino acids, and environmental stress. Developing a bioinformatic search for additional carbon catabolite-responsive regulators in S. aureus, we identified a LysR-type regulator, catabolite control protein E (CcpE), with homology to the Bacillus subtilis CcpC regulator. Inactivation of ccpE in S. aureus strain Newman revealed that CcpE is a positive transcriptional effector of the first two enzymes of the TCA cycle, aconitase (citB) and to a lesser extent citrate synthase (citZ). Consistent with the transcriptional data, aconitase activity dramatically decreased in the ccpE mutant relative to the wild-type strain. The effect of ccpE inactivation on citB transcription and the lesser effect on citZ transcription were also reflected in electrophoretic mobility shift assays where CcpE bound to the citB promoter but not the citZ promoter. Metabolomic studies showed that inactivation of ccpE resulted in increased intracellular concentrations of acetate, citrate, lactate, and alanine, consistent with a redirection of carbon away from the TCA cycle. Taken together, our data suggest that CcpE is a major direct positive regulator of the TCA cycle gene citB. PMID:24194525

  12. 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. PMID:23853324

  13. Effects of a difference in respiratory cycle between treatment planning and irradiation for phase-controlled rescanning and carbon pencil beam scanning

    PubMed Central

    Inaniwa, T; Furukawa, T; Zenklusen, S; Shirai, T; Noda, K

    2013-01-01

    Objective: To evaluate the impact of variation in respiratory cycle between treatment planning and irradiation for pencil beam scanning and phase-controlled rescanning (PCR) on the resulting dose distribution, we conducted a simulation study based on four-dimensional CT (4DCT) data for lung cancer patients. Methods: 4DCT data were acquired for seven patients with lung tumours. Treatment planning was designed to ensure the delivery of 95% of the prescribed dose to the clinical target volume in respective phases of the 4DCT by taking account of intrafractional beam range variations. Carbon ion pencil beam scanning dose distributions were calculated for various respiratory cycles that differed from the reference respiration (=4.4 s) but which stayed regular during irradiation. The number of rescannings was changed to 1, 4 or 8 times. PCR was correlated with the gating window in treatment planning to calculate the beam weighting map. Results: 8×PCR improved dose conformation to the target for all irradiation respiratory cycles. Minimum dose (Dmin) and lowest dose encompassing 95% of the target (D95) values with 4×PCR were decreased from 94.1% and 98.1% to 88.4% and 93.5% with an altered irradiation respiratory cycle of 2.4 s. However, these values were improved with 8×PCR to over 94.9% for Dmin and 98.6% for D95 for respective irradiation respiratory cycles. Conclusion: Pencil beam scanning treatment with eight or more PCRs consistently improved dose conformation for moving lung targets even when different respiratory cycles were used for treatment planning and irradiation. Advances in knowledge: Scanning treatment with eight or more rescannings consistently improved dose homogeneity to a moving target even though respiratory cycles varied during treatment. PMID:23833034

  14. aPKC Phosphorylates p27Xic1, Providing a Mechanistic Link between Apicobasal Polarity and Cell-Cycle Control

    PubMed Central

    Sabherwal, Nitin; Thuret, Raphael; Lea, Robert; Stanley, Peter; Papalopulu, Nancy

    2014-01-01

    Summary 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. PMID:25490266

  15. Characterizing subsurface controls on the Arctic ecosystem carbon cycling across scales using geophysical, in-situ and remote sensing datasets

    NASA Astrophysics Data System (ADS)

    Wainwright, H. M.; Hubbard, S. S.; Dafflon, B.; Ulrich, C.; Peterson, J. E.; Wu, Y.; Hahn, M. S.; Torn, M. S.; Gangodagamage, C.; Rowland, J. C.; Wilson, C. J.; Liljedahl, A.; Gusmeroli, A.; Wullschleger, S. D.

    2013-12-01

    Recent studies suggest that warming climate has significant impacts on the Arctic ecosystems, which could in turn create feedbacks to the climate system. Predicting Arctic ecosystem evolution and feedbacks requires a mechanistic understanding of complex subsurface processes (e.g., permafrost degradation and carbon decomposition) and characterization of key controls on those processes - such as soil moisture, active layer thickness and aqueous geochemistry - from native scales (where the processes occur) to landscape scales considered in climate models. Among others, developing such a predictive understanding requires two advances that we consider in this study: (1) approaches to characterize heterogeneous geocryological and hydrogeochemical properties in high resolution, and their uncertainties, inter-correlations, and correlations to land surface variables; (2) identification of possible zonation that can distinguish between suites of subsurface properties. Our study is carried out at the Department of Energy, Office of Science, Next Generation Ecosystem Experiment (NGEE-Arctic) Site in Barrow, Alaska. Given the importance of quantifying heterogeneous subsurface properties in both high resolution and over large spatial scales, we take advantage of geophysical datasets. We first develop and implement a multiscale Bayesian method to estimate subsurface properties using disparate datasets. We consider in-situ, surface geophysical and remote-sensing datasets along two 500m transects that traverse various ice-wedge polygon features. The method is based on site-specific correlations between geophysical datasets and in-situ measured subsurface properties. The Markov-chain Monte-Carlo sampling is used to compute the posterior distributions. For example, thaw depth and soil moisture are estimated by integrating ground-penetrating radar (GPR), electrical resistivity tomography and in-situ point data. Snow depth coverage is estimated by integrating GPR and point data. The

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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

  1. Cell cycle-controlled proteolysis of a flagellar motor protein that is asymmetrically distributed in the Caulobacter predivisional cell.

    PubMed Central

    Jenal, U; Shapiro, L

    1996-01-01

    Flagellar biogenesis and release are developmental events tightly coupled to the cell cycle of Caulobacter crescentus. A single flagellum is assembled at the swarmer pole of the predivisional cell and is released later in the cell cycle. Here we show that the MS-ring monomer FliF, a central motor component that anchors the flagellum in the cell membrane, is synthesized only in the predivisional cell and is integrated into the membrane at the incipient swarmer cell pole, where it initiates flagellar assembly. FliF is proteolytically turned over during swarmer-to-stalked cell differentiation, coinciding with the loss of the flagellum, suggesting that its degradation is coupled to flagellar release. The membrane topology of FliF was determined and a region of the cytoplasmic C-terminal domain was shown to be required for the interaction with a component of the motor switch. The very C-terminal end of FliF contains a turnover determinant, required for the cell cycle-dependent degradation of the MS-ring. The cell cycle-dependent proteolysis of FliF and the targeting of FliF to the swarmer pole together contribute to the asymmetric localization of the MS-ring in the predivisional cell. Images PMID:8665847

  2. Hypersensitive Photic Responses and Intact Genome-Wide Transcriptional Control without the KaiC Phosphorylation Cycle in the Synechococcus Circadian System

    PubMed Central

    Umetani, Miki; Hosokawa, Norimune; Kitayama, Yohko

    2014-01-01

    Cyanobacteria are unique organisms with remarkably stable circadian oscillations. These are controlled by a network architecture that comprises two regulatory factors: posttranslational oscillation (PTO) and a transcription/translation feedback loop (TTFL). The clock proteins KaiA, KaiB, and KaiC are essential for the circadian rhythm of the unicellular species Synechococcus elongatus PCC 7942. Temperature-compensated autonomous cycling of KaiC phosphorylation has been proposed as the primary oscillator mechanism that maintains the circadian clock, even in the dark, and it controls genome-wide gene expression rhythms under continuous-light conditions (LL). However, the kaiCEE mutation (where “EE” represents the amino acid changes Ser431Glu and Thr432Glu), where phosphorylation cycling does not occur in vivo, has a damped but clear kaiBC expression rhythm with a long period. This suggests that there must be coupling between the robust PTO and the “slave” unstable TTFL. Here, we found that the kaiCEE mutant strain in LL was hypersensitive to the dark acclimation required for phase shifting. Twenty-three percent of the genes in the kaiCEE mutant strain exhibited genome-wide transcriptional rhythms with a period of 48 h in LL. The circadian phase distribution was also conserved significantly in most of the wild-type and kaiCEE mutant strain cycling genes, which suggests that the output mechanism was not damaged severely even in the absence of KaiC phosphorylation cycles. These results strongly suggest that the KaiC phosphorylation cycle is not essential for generating the genome-wide rhythm under light conditions, whereas it is important for appropriate circadian timing in the light and dark. PMID:24244001

  3. Numerical Study of a Groundwater Flow Cycling Controlled By Seawater Intrusion within Karst Conduit Networks Using Modflow-CFP

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Hu, B. X.; Davis, H.

    2014-12-01

    A groundwater flow cycling process between a submarine spring and an inland fresh water spring has been simulated using the latest research version of MODFLOW-CFP (Conduit Flow Process). Spring Creek Springs and Wakulla Spring, which are located in a marine estuary and 18 km inland, respectively, are two major groundwater discharge spots of Woodville Karst Plain (WKP), North Florida, USA. The two springs are found to be connected with karst conduits networks. Rising sea level may put seawater into the Spring Creek Springs and block groundwater discharge, which, in turn, increases freshwater discharge at Wakulla Spring. Three repeating phases in a karst spring flow cycle were proposed from low rainfall period to heavy rainfall period, and back to low rainfall period. During low rainfall periods, seawater flowed back into the conduits at Spring Creek Spring and freshwater was diverted to Wakulla Spring. After heavy rainfall, seawater was pushed back from Spring Creek Spring conduits. A MODFLOW model for WKP was modified to numerically study the groundwater flow cycling and seawater intrusion for three years. Conduit network distribution, high speed groundwater flow and exchange between conduits and matrix domain were simulated through the MODFLOW-CFP model. Rainfall, springs and creeks discharge data were used to calibrate the model. Simulation results catch very well with measurements, and numerically presented the three-phase groundwater cycling. In additional, simulation results were also supported by temperature data measured in conduits, which reflect precipitation recharge to groundwater, and indicate conduit flow direction. Key Words: Karst, Seawater Instrusion, MODFLOW-CFP, Groundwater Cycling

  4. Fragile cycles

    NASA Astrophysics Data System (ADS)

    Bonatti, Ch.; Díaz, L. J.

    We study diffeomorphisms f with heterodimensional cycles, that is, heteroclinic cycles associated to saddles p and q with different indices. Such a cycle is called fragile if there is no diffeomorphism close to f with a robust cycle associated to hyperbolic sets containing the continuations of p and q. We construct a codimension one submanifold of Diff(S×S) that consists of diffeomorphisms with fragile heterodimensional cycles. Our construction holds for any manifold of dimension ⩾4.

  5. 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

  6. Resting states are resting traits--an FMRI study of sex differences and menstrual cycle effects in resting state cognitive control networks.

    PubMed

    Hjelmervik, Helene; Hausmann, Markus; Osnes, Berge; Westerhausen, René; Specht, Karsten

    2014-01-01

    To what degree resting state fMRI is stable or susceptible to internal mind states of the individual is currently an issue of debate. To address this issue, the present study focuses on sex differences and investigates whether resting state fMRI is stable in men and women or changes within relative short-term periods (i.e., across the menstrual cycle). Due to the fact that we recently reported menstrual cycle effects on cognitive control based on data collected during the same sessions, the current study is particularly interested in fronto-parietal resting state networks. Resting state fMRI was measured in sixteen women during three different cycle phases (menstrual, follicular, and luteal). Fifteen men underwent three sessions in corresponding time intervals. We used independent component analysis to identify four fronto-parietal networks. The results showed sex differences in two of these networks with women exhibiting higher functional connectivity in general, including the prefrontal cortex. Menstrual cycle effects on resting states were non-existent. It is concluded that sex differences in resting state fMRI might reflect sexual dimorphisms in the brain rather than transitory activating effects of sex hormones on the functional connectivity in the resting brain. PMID:25057823

  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. Cell cycle control of Wnt/β-catenin signalling by conductin/axin2 through CDC20

    PubMed Central

    Hadjihannas, Michel V; Bernkopf, Dominic B; Brückner, Martina; Behrens, Jürgen

    2012-01-01

    Wnt/β-catenin signalling regulates cell proliferation by modulating the cell cycle and is negatively regulated by conductin/axin2/axil. We show that conductin levels peak at G2/M followed by a rapid decline during return to G1. In line with this, Wnt/β-catenin target genes are low at G2/M and high at G1/S, and β-catenin phosphorylation oscillates during the cell cycle in a conductin-dependent manner. Conductin is degraded by the anaphase-promoting complex/cyclosome cofactor CDC20. Knockdown of CDC20 blocks Wnt signalling through conductin. CDC20-resistant conductin inhibits Wnt signalling and attenuates colony formation of colorectal cancer cells. We propose that CDC20-mediated degradation of conductin regulates Wnt/β-catenin signalling for maximal activity during G1/S. PMID:22322943

  9. 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

  10. The Netrin/RGM receptor, Neogenin, controls adult neurogenesis by promoting neuroblast migration and cell cycle exit.

    PubMed

    O'Leary, Conor J; Bradford, DanaKai; Chen, Min; White, Amanda; Blackmore, Daniel G; Cooper, Helen M

    2015-02-01

    A comprehensive understanding of adult neurogenesis is essential for the development of effective strategies to enhance endogenous neurogenesis in the damaged brain. Olfactory interneurons arise throughout life from stem cells residing in the subventricular zone of the lateral ventricle. Neural precursors then migrate along the rostral migratory stream (RMS) to the olfactory bulb. To ensure a continuous supply of adult-born interneurons, precursor proliferation, migration, and differentiation must be tightly coordinated. Here, we show that the netrin/repulsive guidance molecule receptor, Neogenin, is a key regulator of adult neurogenesis. Neogenin loss-of-function (Neo(gt/gt)) mice exhibit a specific reduction in adult-born calretinin interneurons in the olfactory granule cell layer. In the absence of Neogenin, neuroblasts fail to migrate into the olfactory bulb and instead accumulate in the RMS. In vitro migration assays confirmed that Neogenin is required for Netrin-1-mediated neuroblast migration and chemoattraction. Unexpectedly, we also identified a novel role for Neogenin as a regulator of the neuroblast cell cycle. We observed that those neuroblasts able to reach the Neo(gt/gt) olfactory bulb failed to undergo terminal differentiation. Cell cycle analysis revealed an increase in the number of S-phase neuroblasts within the Neo(gt/gt) RMS and a significant reduction in the number of neuroblasts exiting the cell cycle, providing an explanation for the loss of mature calretinin interneurons in the granule cell layer. Therefore, Neogenin acts to synchronize neuroblast migration and terminal differentiation through the regulation of neuroblast cell cycle kinetics within the neurogenic microenvironment of the RMS. PMID:25308084

  11. 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

  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. Zerumbone, a Sesquiterpene, Controls Proliferation and Induces Cell Cycle Arrest in Human Laryngeal Carcinoma Cell Line Hep-2.

    PubMed

    Jegannathan, Srimathi Devi; Arul, Santhosh; Dayalan, Haripriya

    2016-07-01

    Zerumbone (ZER), a sesquiterpene found in Zingiber zerumbet Smith, has been shown to possess antiproliferative, anticancer, antioxidant, and anti-inflammatory activity against various types of human carcinoma. The molecular mechanism by which ZER mediates its activity against many cancer types is revealed by many studies. Upregulation of proapoptotic molecules and suppression of antiapoptotic gene expression are few of the mechanisms by which ZER mediates its effect. The present study is focused on investigating the effect of ZER on proliferation of laryngeal carcinoma cells (Hep-2). MTT assay results showed that ZER (0.01-100 μM) induced death of Hep-2 cells in a concentration-dependent manner; significant suppression of proliferation of Hep-2 cells was seen with a IC50 value of 15 µM. ZER at a concentration of 15 and 30 μM for 48 h showed early signs of apoptosis as evidenced by confocal microscopy imaging. Flow cytometry studies showed that ZER induced cell cycle arrest. ZER arrested Hep-2 proliferation at S and G2/M phases of cell cycle. In conclusion, these results indicate that ZER has antiproliferative effect and arrests cell cycle in Hep-2 cells in vitro. This could be a potential anticancer drug against laryngeal carcinoma. PMID:27045964

  14. 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.

  15. 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

  16. 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.

  17. A protein kinase antigenically related to pp60v-src possibly involved in yeast cell cycle control: positive in vivo regulation by sterol.

    PubMed Central

    Dahl, C; Biemann, H P; Dahl, J

    1987-01-01

    The effects of ergosterol, yeast's natural sterol, on cell cycling and a protein kinase antigenically related to pp60v-src were examined in a sterol auxotroph of Saccharomyces cerevisiae. Sterol-depleted cells accumulate in an unbudded, G1 state. Cell budding and proliferation are reinitiated upon addition of nonlimiting ergosterol or cholesterol with trace ergosterol, whereas cholesterol or trace ergosterol alone is less effective. Stimulation of a protein kinase associated with immune complexes of yeast protein and anti-pp60v-src shows a positive correlation with exit from the G1 phase following ergosterol addition. Ergosterol-stimulated cells also demonstrate an increase in phosphatidylinositol kinase activity. The data suggest that hormonal levels of ergosterol (effective concentration, approximately equal to 1 nM) participate in a signaling process associated with a protein kinase possibly involved in yeast cell cycle control. Images PMID:2438691

  18. 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.

  19. Elevated lung cancer risk is associated with deficiencies in cell cycle checkpoints: Genotype and phenotype analyses from a case-control study

    PubMed Central

    Zheng, Yun-Ling; Kosti, Ourania; Loffredo, Christopher; Bowman, Elise; Mechanic, Leah; Perlmutter, Donna; Jones, Raymond; Shields, Peter G.; Harris, Curtis

    2010-01-01

    Cell cycle checkpoints play critical roles in the maintenance of genomic integrity and inactivation of checkpoint genes, and are frequently perturbed in most cancers. In a case-control study of 299 non-small cell lung cancer cases and 550 controls in Maryland, we investigated the association between γ-radiation-induced G2/M arrest in cultured blood lymphocytes and lung cancer risk, and examined genotype-phenotype correlations between genetic polymorphisms of 20 genes involving in DNA repair and cell cycle control and γ-radiation-induced G2/M arrest. The study was specifically designed to examine race and gender differences in risk factors. Our data indicated that a less efficient DNA damage-induced G2/M checkpoint was associated with an increased risk of lung cancer in African American women with an adjusted odds ratio (OR) of 2.63 (95% CI = 1.01 – 7.26); there were no statistically significant associations for Caucasians, or African American men. When the African American women were categorized into quartiles, a significant reverse trend of decreased G2/M checkpoint function and increased lung cancer risk was present, with lowest-vs-highest quartile OR of 13.72 (95% CI = 2.30 – 81.92, Ptrend < 0.01). Genotype-phenotype correlation analysis indicated that polymorphisms in ATM, CDC25C, CDKN1A, BRCA2, ERCC6, TP53, and TP53BP1 genes were significantly associated with the γ-radiation-induced G2/M arrest phenotype. This study provides evidence that a less efficient G2/M checkpoint is significantly associated with lung cancer risk in African American women. The data also suggested that the function of G2/M checkpoint is modulated by genetic polymorphisms in genes involved in DNA repair and cell cycle control. PMID:19626602

  20. Moving-bed gasification - combined-cycle control study. Volume 1: results and conclusions, Case 1 - air-blown dry-ash operation. Final report

    SciTech Connect

    Ahner, D.J.; Brower, A.S.; Dawes, M.H.; Patel, A.S.

    1981-03-01

    A simulation study has been conducted to investigate the inherent process dynamics and required control strategies for an integrated coal gasification/combined cycle (GCC) power plant to operate successfully under load-changing conditions to meet power system requirements. The simulated GCC plant configuration is similar to the flowsheet developed in earlier EPRI economic studies (RP239), based on an air-blown, dry-ash, moving-bed gasifier of the Lurgi-type. A following GCC plant control study will be based on a Lurgi-type gasifier modified for oxygen-blown, slagging operations such as that being developed by British Gas Corporation. A large ditial computer simulation model of the GCC plant operating on a large utility power system network was developed to examine alternate plant control strategies. Gas turbine-lead and gasifier-lead control modes were evaluated with respect to power system requirements for daily load following, tie-line flow regulation with thermal backup, and frequency regulation. Inherent features of the gasifier led to unique process dynamics for the GCC plant. Sizeable transients were observed during load-changing operations, both in the fuel process and the steam system. However, the plant compensated effectively for such transients with a modified gas turbine-lead control strategy, by making use of fast-responding gas turbine controls and the large inherent volume of the fuel process. The results verify the capability of the GCC plant to operate with the fuel process closely integrated with the combined cycle plant under rapidly changing conditions. Furthermore, a GCC plant control strategy was developed which can successfully meet power sytem requirements within fuel system limitations, allowing an overall plant response rate of four (4) percent per minute.

  1. Flux control exerted by mitochondrial outer membrane carnitine palmitoyltransferase over beta-oxidation, ketogenesis and tricarboxylic acid cycle activity in hepatocytes isolated from rats in different metabolic states.

    PubMed Central

    Drynan, L; Quant, P A; Zammit, V A

    1996-01-01

    The Flux Control Coefficients of mitochondrial outer membrane carnitine palmitoyltransferase (CPT I) with respect to the overall rates of beta-oxidation, ketogenesis and tricarboxylic acid cycle activity were measured in hepatocytes isolated from rats in different metabolic states (fed, 24 h-starved, starved-refed and starved/insulin-treated). These conditions were chosen because there is controversy as to whether, when significant control ceases to be exerted by CPT I over the rate of fatty oxidation [Moir and Zammit (1994) Trends Biochem. Sci. 19, 313-317], this is transferred to one or more steps proximal to acylcarnitine synthesis (e.g. decreased delivery of fatty acids to the liver) or to the reaction catalysed by mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase [Hegardt (1995) Biochem. Soc. Trans. 23, 486-490]. Therefore isolated hepatocytes were used in the present study to exclude the involvement of changes in the rate of delivery of non-esterified fatty acids (NEFA) to the liver, such as occur in vivo, and to ascertain whether, under conditions of constant supply of NEFA, CPT I retains control over the relevant fluxes of fatty acid oxidation to ketones and carbon dioxide, or whether control is transferred to another (intrahepatocytic) site. The results clearly show that the Flux Control Coefficients of CPT I with respect to overall beta-oxidation and ketogenesis are very high under all conditions investigated, indicating that control is not lost to another intrahepatic site during the metabolic transitions studied. The control of CPT I over tricarboxylic acid cycle activity was always very low. The significance of these findings for the integration of fatty acid and carbohydrate metabolism in the liver is discussed. PMID:8760364

  2. 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 ...

  3. Reduced mRNA Expression of PTGDS in Peripheral Blood Mononuclear Cells of Rapid-Cycling Bipolar Disorder Patients Compared with Healthy Control Subjects

    PubMed Central

    Peijs, Lone; Kessing, Lars Vedel; Vinberg, Maj

    2015-01-01

    Background: Disturbances related to the arachidonic acid cascade and prostaglandin metabolism may be involved in the pathophysiology of bipolar disorder, as supported by a recent genome-wide association study meta-analysis; however, evidence from clinical studies on a transcriptional level is lacking. Two enzymes in the arachidonic acid cascade are the prostaglandin D synthase (PTGDS), which catalyzes the conversion of prostaglandin H2 to prostaglandin D2 (PGD2), and the aldo-keto reductase family 1 member C3 (AKR1C3), which catalyzes the reduction of PGD2. We aimed to test the hypothesis that mRNA expression of PTGDS and AKR1C3 is deregulated in rapid-cycling disorder patients in a euthymic or current affective state compared with healthy control subjects, and that expression alters with affective states. Methods: PTGDS and AKR1C3 mRNA expression in peripheral blood mononuclear cells was measured in 37 rapid-cycling bipolar disorder patients and 40 age- and gender-matched healthy control subjects using reverse transcription quantitative real-time polymerase chain reaction. Repeated measurements of PTGDS and AKR1C3 mRNA expression were obtained in various affective states during 6–12 months and compared with repeated measurements in healthy control subjects. Results: Adjusted for age and gender, PTGDS mRNA expression was down-regulated in rapid-cycling bipolar disorder patients in a euthymic, depressive, and manic/hypomanic state compared with healthy control subjects. No difference in PTGDS mRNA expression was observed between affective states. AKR1C3 mRNA expression did not differ between bipolar disorder patients in any affective state or in comparison with healthy control subjects. Conclusions: The results suggest a role for aberrantly-regulated PTGDS mRNA expression in rapid-cycling bipolar disorder. The sample size was limited; replication of the findings in larger, independent samples is warranted to further explore the role of the arachidonic acid cascade

  4. 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

  5. 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.

  6. Genetic and Proteomic Evidence for Roles of Drosophila SUMO in Cell Cycle Control, Ras Signaling, and Early Pattern Formation

    PubMed Central

    Nie, Minghua; Xie, Yongming; Loo, Joseph A.; Courey, Albert J.

    2009-01-01

    SUMO is a protein modifier that is vital for multicellular development. Here we present the first system-wide analysis, combining multiple approaches, to correlate the sumoylated proteome (SUMO-ome) in a multicellular organism with the developmental roles of SUMO. Using mass-spectrometry-based protein identification, we found over 140 largely novel SUMO conjugates in the early Drosophila embryo. Enriched functional groups include proteins involved in Ras signaling, cell cycle, and pattern formation. In support of the functional significance of these findings, sumo germline clone embryos exhibited phenotypes indicative of defects in these same three processes. Our cell culture and immunolocalization studies further substantiate roles for SUMO in Ras signaling and cell cycle regulation. For example, we found that SUMO is required for efficient Ras-mediated MAP kinase activation upstream or at the level of Ras activation. We further found that SUMO is dynamically localized during mitosis to the condensed chromosomes, and later also to the midbody. Polo kinase, a SUMO substrate found in our screen, partially colocalizes with SUMO at both sites. These studies show that SUMO coordinates multiple regulatory processes during oogenesis and early embryogenesis. In addition, our database of sumoylated proteins provides a valuable resource for those studying the roles of SUMO in development. PMID:19529778

  7. 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.

  8. Brittle Culm 12, a dual-targeting kinesin-4 protein, controls cell-cycle progression and wall properties in rice

    PubMed Central

    Zhang, Mu; Zhang, Baocai; Qian, Qian; Yu, Yanchun; Li, Rui; Zhang, Junwen; Liu, Xiangling; Zeng, Dali; Li, Jiayang; Zhou, Yihua

    2010-01-01

    Kinesins are encoded by a large gene family involved in many basic processes of plant development. However, the number of functionally identified kinesins in rice is very limited. Here, we report the functional characterization of Brittle Culm12 (BC12), a gene encoding a kinesin-4 protein. bc12 mutants display dwarfism resulting from a significant reduction in cell number and brittleness due to an alteration in cellulose microfibril orientation and wall composition. BC12 is expressed mainly in tissues undergoing cell division and secondary wall thickening. In vitro biochemical analyses verified BC12 as an authentic motor protein. This protein was present in both the nucleus and cytoplasm and associated with microtubule arrays during cell division. Mitotic microtubule array comparison, flow cytometric analysis and expression assays of cyclin-dependent kinase (CDK) complexes in root-tip cells showed that cell-cycle progression is affected in bc12 mutants. BC12 is very probably regulated by CDKA;3 based on yeast two-hybrid and microarray data. Therefore, BC12 functions as a dual-targeting kinesin protein and is implicated in cell-cycle progression, cellulose microfibril deposition and wall composition in the monocot plant rice. PMID:20444225

  9. 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.

  10. Cell cycle control and HIV-1 susceptibility are linked by CDK6-dependent CDK2 phosphorylation of SAMHD1 in myeloid and lymphoid cells.

    PubMed

    Pauls, Eduardo; Ruiz, Alba; Badia, Roger; Permanyer, Marc; Gubern, Albert; Riveira-Muñoz, Eva; Torres-Torronteras, Javier; Alvarez, Mar; Mothe, Beatriz; Brander, Christian; Crespo, Manel; Menéndez-Arias, Luis; Clotet, Bonaventura; Keppler, Oliver T; Martí, Ramon; Posas, Francesc; Ballana, Ester; Esté, José A

    2014-08-15

    Proliferating cells are preferentially susceptible to infection by retroviruses. Sterile α motif and HD domain-containing protein-1 (SAMHD1) is a recently described deoxynucleotide phosphohydrolase controlling the size of the intracellular deoxynucleotide triphosphate (dNTP) pool, a limiting factor for retroviral reverse transcription in noncycling cells. Proliferating (Ki67(+)) primary CD4(+) T cells or macrophages express a phosphorylated form of SAMHD1 that corresponds with susceptibility to infection in cell culture. We identified cyclin-dependent kinase (CDK) 6 as an upstream regulator of CDK2 controlling SAMHD1 phosphorylation in primary T cells and macrophages susceptible to infection by HIV-1. In turn, CDK2 was strongly linked to cell cycle progression and coordinated SAMHD1 phosphorylation and inactivation. CDK inhibitors specifically blocked HIV-1 infection at the reverse transcription step in a SAMHD1-dependent manner, reducing the intracellular dNTP pool. Our findings identify a direct relationship between control of the cell cycle by CDK6 and SAMHD1 activity, which is important for replication of lentiviruses, as well as other viruses whose replication may be regulated by intracellular dNTP availability. PMID:25015816

  11. 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

  12. 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

  13. A thioesterase from an iterative fungal polyketide synthase shows macrocylization and cross-coupling activity, and may play a role in controlling iterative cycling through product off loading†

    PubMed Central

    Wang, Meng; Zhou, Hui; Wirz, Monica; Tang, Yi; Boddy, Christopher N.

    2009-01-01

    Zearalenone, a fungal macrocyclic polyketide, is a member of the resorcylic acid lactone family. Herein, we characterize in vitro the thioesterase from PKS13 in zearalenone biosynthesis (Zea TE). The excised Zea TE catalyzes macrocyclization of a linear thioester activated model of zearalenone. Zea TE also catalyzes the cross coupling of a benzoyl thioester with alcohols and amines. Kinetic characterization of the cross coupling is consistent with a ping-pong bi-bi mechanism, confirming an acyl-enzyme intermediate. Finally, the substrate specificity of the Zea TE indicates the TE may help control iterative cycling on PKS13 by rapidly off loading the final resorcylate containing product. PMID:19530704

  14. Statistical analysis of the results of tests of weld joints of petroleum apparatus made by electroslag welding with control of the thermal cycles

    SciTech Connect

    Khakimov, A.N.; Agafonov, V.V.; Efimenko, L.A.; Zakharov, V.A.

    1984-01-01

    Electroslag welding with control of the thermal cycles provides weld joints with the required mechanical properties, reduces the labor requirements and saves on costs. A statistical analysis of the results of sample compounds of weld joints of apparatus from specified sources derives strength indices, and the mechanical test results are treated by the methods of mathematical statistics with the use of a computer. It is found that electroslag welding can be used in the production of apparatus of 20K, 20 YuCh, 09G2S, and 16GS steels.

  15. 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

  16. In Vitro Antiproliferative Effect of Arthrocnemum indicum Extracts on Caco-2 Cancer Cells through Cell Cycle Control and Related Phenol LC-TOF-MS Identification

    PubMed Central

    Boulaaba, Mondher; Mkadmini, Khaoula; Tsolmon, Soninkhishig; Han, Junkyu; Smaoui, Abderrazak; Kawada, Kiyokazu; Ksouri, Riadh; Isoda, Hiroko; Abdelly, Chedly

    2013-01-01

    This study aimed to determinate phenolic contents and antioxidant activities of the halophyte Arthrocnemum indicum shoot extracts. Moreover, the anticancer effect of this plant on human colon cancer cells and the likely underlying mechanisms were also investigated, and the major phenols were identified by LC-ESI-TOF-MS. Results showed that shoot extracts had an antiproliferative effect of about 55% as compared to the control and were characterised by substantial total polyphenol content (19 mg GAE/g DW) and high antioxidant activity (IC50 = 40 μg/mL for DPPH test). DAPI staining revealed that these extracts decrease DNA synthesis and reduce the proliferation of Caco-2 cells which were stopped at the G2/M phase. The changes in the cell-cycle-associated proteins (cyclin B1, p38, Erk1/2, Chk1, and Chk2) correlate with the changes in cell cycle distribution. Eight phenolic compounds were also identified. In conclusion, A. indicum showed interesting antioxidant capacities associated with a significant antiproliferative effect explained by a cell cycle blocking at the G2/M phase. Taken together, these data suggest that A. indicum could be a promising candidate species as a source of anticancer molecules. PMID:24348703

  17. Host cell factor-1 recruitment to E2F-bound and cell-cycle-control genes is mediated by THAP11 and ZNF143.

    PubMed

    Parker, J Brandon; Yin, Hanwei; Vinckevicius, Aurimas; Chakravarti, Debabrata

    2014-11-01

    Host cell factor-1 (HCF-1) is a metazoan transcriptional coregulator essential for cell-cycle progression and cell proliferation. Current models suggest a mechanism whereby HCF-1 functions as a direct coregulator 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 model in which a THAP11/ZNF143/HCF-1 complex is a critical component of the transcriptional regulatory network governing cell proliferation. PMID:25437553

  18. A comparative study on photoperiodic control of seasonal cycles in the females of migratory yellow breasted bunting and the resident tree sparrow.

    PubMed

    Dixit, Anand S; Singh, Namram S; Sougrakpam, Ramita

    2014-11-01

    We studied the detailed pattern of seasonality in reproduction and the associated functions in the females of migratory yellow breasted bunting (Emberiza aureola) and resident tree sparrow (Passer montanus) under natural and artificial photoperiods. They exhibited seasonal cycles of ovarian development, moult and bill colour under natural photoperiods which were found linked to the annual solar cycle. Photosensitive birds of both the species, when exposed to 9L/15D, 12L/12D and 14L/10D for 18 months, showed follicular growth followed by regression and development of photorefractoriness only under artificial long photoperiods (12L/12D and 14L/10D). Fattening and body weight increase were noticed only in bunting exposed to long natural and artificial photoperiods. Both species exhibited complete postnuptial moult of body and primary feathers under long natural and artificial photoperiods (except primaries moult under 12L/12D in bunting) that progressed with gonadal regression suggesting their photoperiodic control. In addition, bunting also showed an incomplete prenuptial moult of body feathers during gonadal stimulation. Thus, the moult and body weight responses of bunting differed significantly when compared with those of sparrows. Exposure of photosensitive birds to 24 h light-dark cycles with increasing photophase suggested that the threshold photoperiods of about 12 h in bunting and about 11 h in sparrow initiate follicular growth exceeding which the rate of growth increases with increasing photoperiods. However, the threshold photoperiod was found to be response specific in bunting. PMID:25246220

  19. 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

  20. 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. PMID:27093084

  1. Maternal embryonic leucine zipper kinase (MELK): a novel regulator in cell cycle control, embryonic development, and cancer.

    PubMed

    Jiang, Pengfei; Zhang, Deli

    2013-01-01

    Maternal embryonic leucine zipper kinase (MELK) functions as a modulator of intracellular signaling and affects various cellular and biological processes, including cell cycle, cell proliferation, apoptosis, spliceosome assembly, gene expression, embryonic development, hematopoiesis, and oncogenesis. In these cellular processes, MELK functions by binding to numerous proteins. In general, the effects of multiple protein interactions with MELK are oncogenic in nature, and the overexpression of MELK in kinds of cancer provides some evidence that it may be involved in tumorigenic process. In this review, our current knowledge of MELK function and recent discoveries in MELK signaling pathway were discussed. The regulation of MELK in cancers and its potential as a therapeutic target were also described. PMID:24185907

  2. CEP-stable tunable THz-emission originating from laser-waveform-controlled sub-cycle plasma-electron bursts.

    PubMed

    Balčiūnas, T; Lorenc, D; Ivanov, M; Smirnova, O; Zheltikov, A M; Dietze, D; Unterrainer, K; Rathje, T; Paulus, G G; Baltuška, A; Haessler, S

    2015-06-15

    We study THz-emission from a plasma driven by an incommensurate-frequency two-colour laser field. A semi-classical transient electron current model is derived from a fully quantum-mechanical description of the emission process in terms of sub-cycle field-ionization followed by continuum-continuum electron transitions. For the experiment, a CEP-locked laser and a near-degenerate optical parametric amplifier are used to produce two-colour pulses that consist of the fundamental and its near-half frequency. By choosing two incommensurate frequencies, the frequency of the CEP-stable THz-emission can be continuously tuned into the mid-IR range. This measured frequency dependence of the THz-emission is found to be consistent with the semi-classical transient electron current model, similar to the Brunel mechanism of harmonic generation. PMID:26193509

  3. 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

  4. 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

  5. Characterization of a novel origin recognition complex-like complex: implications for DNA recognition, cell cycle control, and locus-specific gene amplification.

    PubMed

    Mohammad, Mohammad; York, Randall D; Hommel, Jonathan; Kapler, Geoffrey M

    2003-07-01

    The origin recognition complex (ORC) plays a central role in eukaryotic DNA replication. Here we describe a unique ORC-like complex in Tetrahymena thermophila, TIF4, which bound in an ATP-dependent manner to sequences required for cell cycle-controlled replication and gene amplification (ribosomal DNA [rDNA] type I elements). TIF4's mode of DNA recognition was distinct from that of other characterized ORCs, as it bound exclusively to single-stranded DNA. In contrast to yeast ORCs, TIF4 DNA binding activity was cell cycle regulated and peaked during S phase, coincident with the redistribution of the Orc2-related subunit, p69, from the cytoplasm to the macronucleus. Origin-binding activity and nuclear p69 immunoreactivity were further regulated during development, where they distinguished replicating from nonreplicating nuclei. Both activities were lost from germ line micronuclei following the programmed arrest of micronuclear replication. Replicating macronuclei stained with Orc2 antibodies throughout development in wild-type cells but failed to do so in the amplification-defective rmm11 mutant. Collectively, these findings indicate that the regulation of TIF4 is intimately tied to the cell cycle and developmentally programmed replication cycles. They further implicate TIF4 in rDNA gene amplification. As type I elements interact with other sequence-specific single-strand breaks (in vitro and in vivo), the dynamic interplay of Orc-like (TIF4) and non-ORC-like proteins with this replication determinant may provide a novel mechanism for regulation. PMID:12832485

  6. Implications of time-delayed feedback control on limit cycle oscillation of a two-dimensional supersonic lifting surface,

    NASA Astrophysics Data System (ADS)

    Yu, P.; Chen, Z.; Librescu, L.; Marzocca, P.

    2007-07-01

    In this paper, the problem of implications of time delay feedback control of a two-dimensional supersonic lifting surface on the flutter boundary and on its character, that is, benign or catastrophic, is addressed. In this context, the structural and aerodynamic nonlinearities are included in the aeroelastic governing equations. The model and the associated theory are developed for linear and nonlinear plunging and pitching full-state proportional and velocity feedback controls. Center manifold reduction and normal form theory are applied to investigate the stability in the post-flutter flight speed regimes. Numerical simulations are carried out to determine the implications of time delay in the considered controls, but are restricted to the cases of proportional feedback control and no structural damping.

  7. 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).

  8. 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

  9. Perturbations of cell cycle control in T cells contribute to the different outcomes of simian immunodeficiency virus infection in rhesus macaques and sooty mangabeys.

    PubMed

    Paiardini, M; Cervasi, B; Sumpter, B; McClure, H M; Sodora, D L; Magnani, M; Staprans, S I; Piedimonte, G; Silvestri, G

    2006-01-01

    In contrast to human immunodeficiency virus (HIV) infection of humans and experimental simian immunodeficiency virus (SIV) infection of rhesus macaques (RMs), SIV infection of sooty mangabeys (SMs), a natural host African monkey species, is typically nonpathogenic and associated with preservation of CD4+ T-cell counts despite chronic high levels of viral replication. In previous studies, we have shown that the lack of SIV disease progression in SMs is related to lower levels of immune activation and bystander T-cell apoptosis compared to those of pathogenic HIV/SIV infection (G. Silvestri, D. Sodora, R. Koup, M. Paiardini, S. O'Neil, H. M. McClure, S. I. Staprans, and M. B. Feinberg, Immunity 18:441-452, 2003; G. Silvestri, A. Fedanov, S. Germon, N. Kozyr, W. J. Kaiser, D. A. Garber, H. M. McClure, M. B. Feinberg, and S. I. Staprans, J. Virol. 79:4043-4054, 2005). In HIV-infected patients, increased T-cell susceptibility to apoptosis is associated with a complex cell cycle dysregulation (CCD) that involves increased activation of the cyclin B/p34-cdc2 complex and abnormal nucleolar structure with dysregulation of nucleolin turnover. Here we report that CCD is also present during pathogenic SIV infection of RMs, and its extent correlates with the level of immune activation and T-cell apoptosis. In marked contrast, naturally SIV-infected SMs show normal regulation of cell cycle control (i.e., normal intracellular levels of cyclin B and preserved nucleolin turnover) and a low propensity to apoptosis in both peripheral blood- and lymph node-derived T cells. The absence of significant CCD in the AIDS-free, non-immune-activated SMs despite high levels of viral replication indicates that CCD is a marker of disease progression during lentiviral infection and supports the hypothesis that the preservation of cell cycle control may help to confer the disease-resistant phenotype of SIV-infected SMs. PMID:16378966

  10. Perturbations of Cell Cycle Control in T Cells Contribute to the Different Outcomes of Simian Immunodeficiency Virus Infection in Rhesus Macaques and Sooty Mangabeys

    PubMed Central

    Paiardini, M.; Cervasi, B.; Sumpter, B.; McClure, H. M.; Sodora, D. L.; Magnani, M.; Staprans, S. I.; Piedimonte, G.; Silvestri, G.

    2006-01-01

    In contrast to human immunodeficiency virus (HIV) infection of humans and experimental simian immunodeficiency virus (SIV) infection of rhesus macaques (RMs), SIV infection of sooty mangabeys (SMs), a natural host African monkey species, is typically nonpathogenic and associated with preservation of CD4+ T-cell counts despite chronic high levels of viral replication. In previous studies, we have shown that the lack of SIV disease progression in SMs is related to lower levels of immune activation and bystander T-cell apoptosis compared to those of pathogenic HIV/SIV infection (G. Silvestri, D. Sodora, R. Koup, M. Paiardini, S. O’Neil, H. M. McClure, S. I. Staprans, and M. B. Feinberg, Immunity 18:441-452, 2003; G. Silvestri, A. Fedanov, S. Germon, N. Kozyr, W. J. Kaiser, D. A. Garber, H. M. McClure, M. B. Feinberg, and S. I. Staprans, J. Virol. 79:4043-4054, 2005). In HIV-infected patients, increased T-cell susceptibility to apoptosis is associated with a complex cell cycle dysregulation (CCD) that involves increased activation of the cyclin B/p34-cdc2 complex and abnormal nucleolar structure with dysregulation of nucleolin turnover. Here we report that CCD is also present during pathogenic SIV infection of RMs, and its extent correlates with the level of immune activation and T-cell apoptosis. In marked contrast, naturally SIV-infected SMs show normal regulation of cell cycle control (i.e., normal intracellular levels of cyclin B and preserved nucleolin turnover) and a low propensity to apoptosis in both peripheral blood- and lymph node-derived T cells. The absence of significant CCD in the AIDS-free, non-immune-activated SMs despite high levels of viral replication indicates that CCD is a marker of disease progression during lentiviral infection and supports the hypothesis that the preservation of cell cycle control may help to confer the disease-resistant phenotype of SIV-infected SMs. PMID:16378966

  11. Simulation, Model Verification and Controls Development of Brayton Cycle PM Alternator: Testing and Simulation of 2 KW PM Generator with Diode Bridge Output

    NASA Technical Reports Server (NTRS)

    Stankovic, Ana V.

    2003-01-01

    Professor Stankovic will be developing and refining Simulink based models of the PM alternator and comparing the simulation results with experimental measurements taken from the unit. Her first task is to validate the models using the experimental data. Her next task is to develop alternative control techniques for the application of the Brayton Cycle PM Alternator in a nuclear electric propulsion vehicle. The control techniques will be first simulated using the validated models then tried experimentally with hardware available at NASA. Testing and simulation of a 2KW PM synchronous generator with diode bridge output is described. The parameters of a synchronous PM generator have been measured and used in simulation. Test procedures have been developed to verify the PM generator model with diode bridge output. Experimental and simulation results are in excellent agreement.

  12. The DEAD-box RNA helicase 51 controls non-small cell lung cancer proliferation by regulating cell cycle progression via multiple pathways.

    PubMed

    Wang, Xiaojing; Liu, Hongli; Zhao, Chengling; Li, Wei; Xu, Huanbai; Chen, Yuqing

    2016-01-01

    The genetic regulation of cell cycle progression and cell proliferation plays a role in the growth of non-small cell lung cancer (NSCLC), one of the most common causes of cancer-related mortality. Although DEAD-box RNA helicases are known to play a role in cancer development, including lung cancer, the potential involvement of the novel family member DDX51 has not yet been investigated. In the current study we assessed the role of DDX51 in NSCLC using a siRNA-based approach. DDX51 siRNA-expressing cells exhibited a slower cell proliferation rate and underwent arrest in S-phase of the cell cycle compared with control cells. Microarray analyses revealed that DDX51siRNA expression resulted in the dysregulation of a number of cell signalling pathways. Moreover, injection of DDX51 siRNA into an animal model resulted in the formation of smaller tumours compared with the control group. We also assessed the expression of DDX51 in patients with NSCLC, and the data revealed that the expression was correlated with patient age but no other risk factors. Overall, our data suggest for the first time that DDX51 aids cell cancer proliferation by regulating multiple signalling pathways, and that this protein might be a therapeutic target for NSCLC. PMID:27198888

  13. Cabergoline for preventing ovarian hyperstimulation syndrome in women at risk undergoing in vitro fertilization/intracytoplasmic sperm injection treatment cycles: A randomized controlled study

    PubMed Central

    Kılıç, Niyazi; Özdemir, Özhan; Başar, Hakan Cevdet; Demircan, Fadime; Ekmez, Fırat; Yücel, Oğuz

    2015-01-01

    Background: Ovarian hyperstimulation syndrome (OHSS) is the most serious and potentially life-threatening iatrogenic complication associated with ovarian stimulation during assisted reproductive technology protocols. The aim of this study was to evaluate the role of dopamine agonist as a preventive strategy of OHSS in women at high risk in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment cycles. Methods: Seventy women at risk to develop OHSS undergoing IVF/ICSI treatment cycle were included. The study group received 0.5 mg of cabergoline for 8 days from the day of human chorionic gonadotropin administration in comparison to those who undergo no treatment for the prevention of OHSS. The reduction of the incidence of OHSS was the primary outcome. Results: The actual incidence of OHSS was 8.33% in the cabergoline group and 20.58% in the control group. Thus, the incidence of OHSS was significantly reduced, by almost 60%, in the cabergoline group in comparison with the control group (relative ratios: 0.4, 95% confidence interval: 0.18–0.79). Conclusion: Prophylactic treatment with the dopamine agonist, cabergoline, reduces the incidence of OHSS in women at high risk undergoing IVF/ICSI treatment. However, the effects of cabergoline on important outcomes, namely, live birth, miscarriage, and congenital abnormalities are still uncertain. PMID:26629467

  14. The DEAD-box RNA helicase 51 controls non-small cell lung cancer proliferation by regulating cell cycle progression via multiple pathways

    PubMed Central

    Wang, Xiaojing; Liu, Hongli; Zhao, Chengling; Li, Wei; Xu, Huanbai; Chen, Yuqing

    2016-01-01

    The genetic regulation of cell cycle progression and cell proliferation plays a role in the growth of non-small cell lung cancer (NSCLC), one of the most common causes of cancer-related mortality. Although DEAD-box RNA helicases are known to play a role in cancer development, including lung cancer, the potential involvement of the novel family member DDX51 has not yet been investigated. In the current study we assessed the role of DDX51 in NSCLC using a siRNA-based approach. DDX51 siRNA-expressing cells exhibited a slower cell proliferation rate and underwent arrest in S-phase of the cell cycle compared with control cells. Microarray analyses revealed that DDX51siRNA expression resulted in the dysregulation of a number of cell signalling pathways. Moreover, injection of DDX51 siRNA into an animal model resulted in the formation of smaller tumours compared with the control group. We also assessed the expression of DDX51 in patients with NSCLC, and the data revealed that the expression was correlated with patient age but no other risk factors. Overall, our data suggest for the first time that DDX51 aids cell cancer proliferation by regulating multiple signalling pathways, and that this protein might be a therapeutic target for NSCLC. PMID:27198888

  15. A comparative study of RNA and DNA as internal gene expression controls early in the developmental cycle of Chlamydia pneumoniae.

    PubMed

    Engström, Patrik; Bailey, Leslie; Onskog, Thomas; Bergström, Sven; Johansson, Jörgen

    2010-03-01

    Many microbial pathogens invade and proliferate within host cells and the molecular mechanism underlying this behavior is currently being revealed for several bacterial species. Testing clinically relevant antibacterial compounds and elucidating their effects on gene expression requires adequate controls, especially when studying genetically intractable organisms such as Chlamydia spp., for which various gene fusions cannot be constructed. Until now, relative mRNA levels in Chlamydia have been measured using different internal gene expression controls, including 16S rRNA, mRNAs, and DNA. Here, we compared the advantages and disadvantages of various internal expression controls during the early phase of Chlamydia pneumoniae development. The relative abundance of target mRNAs varied using the different internal control RNAs. This was partly due to variation in the transcript stability of the RNA species. Also, seven out of nine of the analyzed RNAs increased fivefold or more between 2 and 14 h postinfection, while the amount of DNA and number of cells remained essentially unaltered. Our results suggest that RNA should not be used as a gene expression control during the early phase of Chlamydia development, and that intrinsic bacterial DNA is preferable for that purpose because it is stable, abundant, and its relative amount is generally correlated with bacterial numbers. PMID:20002746

  16. Cell-cycle control as a target for calcium, hormonal and developmental signals: the role of phosphorylation in the retinoblastoma-centred pathway

    PubMed Central

    Dudits, Dénes; Ábrahám, Edit; Miskolczi, Pál; Ayaydin, Ferhan; Bilgin, Metin; Horváth, Gábor V.

    2011-01-01

    Background During the life cycle of plants, both embryogenic and post-embryogenic growth are essentially based on cell division and cell expansion that are under the control of inherited developmental programmes modified by hormonal and environmental stimuli. Considering either stimulation or inhibition of plant growth, the key role of plant hormones in the modification of cell division activities or in the initiation of differentiation is well supported by experimental data. At the same time there is only limited insight into the molecular events that provide linkage between the regulation of cell-cycle progression and hormonal and developmental control. Studies indicate that there are several alternative ways by which hormonal signalling networks can influence cell division parameters and establish functional links between regulatory pathways of cell-cycle progression and genes and protein complexes involved in organ development. Scope An overview is given here of key components in plant cell division control as acceptors of hormonal and developmental signals during organ formation and growth. Selected examples are presented to highlight the potential role of Ca2+-signalling, the complex actions of auxin and cytokinins, regulation by transcription factors and alteration of retinoblastoma-related proteins by phosphorylation. Conclusions Auxins and abscisic acid can directly influence expression of cyclin, cyclin-dependent kinase (CDK) genes and activities of CDK complexes. D-type cyclins are primary targets for cytokinins and over-expression of CyclinD3;1 can enhance auxin responses in roots. A set of auxin-activated genes (AXR1–ARGOS–ANT) controls cell number and organ size through modification of CyclinD3;1 gene expression. The SHORT ROOT (SHR) and SCARECROW (SCR) transcriptional factors determine root patterning by activation of the CYCD6;1 gene. Over-expression of the EBP1 gene (plant homologue of the ErbB-3 epidermal growth factor receptor-binding protein

  17. 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.

  18. 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.

  19. 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.

  20. Comparison of Letrozole and Clomiphene Citrate Efficacy along with Gonadotrophins in Controlled Ovarian Hyperstimulation for Intrauterine Insemination Cycles

    PubMed Central

    HaqNawaz, Fauzia; Virk, Saadia; Qadir, Tasleem; Imam, Saadia; Rizvi, Javed

    2013-01-01

    Background We performed this study to investigate and compare the effects of Letrozole and gonadotrophins versus Clomiphene Citrate and gonadotrophins in women undergoing superovulation for Intrauterine Insemination (IUI). Methods We performed this prospective cohort study at Australian Concept and Fertility centre, Karachi Pakistan. Women younger than 40 years of age with patent fallopian tubes and infertility of more than 2 years in duration who were undergoing IUI and gonadotrophins therapy were divided into two groups, one received Letro-zole for 5 days and another received Clomiphene Citrate for 5 days. Results All 500 IUI treatment cycles conducted from March 2008 to March 2010 were included. Patients co-treated with Letrozole required fewer gonadotrophins administrations (median difference, 300 IU (95% confidence interval (CI), 225−375 IU), developed more follicles larger than 14 mm (median difference, 1 follicle, 95% CI, 1−2 follicles), and had a thicker endometrium (median difference, 1 mm, 95% CI, 0.4–1.6 mm). The pregnancy rate was not significantly different between two groups (11% vs. 12.6%). Conclusion The addition of Letrozole to gonadotrophins decreases gonadotrophins requirements and improves endometrial thickness, without a significant effect on pregnancy rates. An improved pregnancy rate has been observed in older age group, >35 years with Letrozole. PMID:24163798

  1. Strong-field control of the dissociative ionization of N2O with near-single-cycle pulses

    NASA Astrophysics Data System (ADS)

    Kübel, M.; Alnaser, A. S.; Bergues, B.; Pischke, T.; Schmidt, J.; Deng, Y.; Jendrzejewski, C.; Ullrich, J.; Paulus, G. G.; Azzeer, A. M.; Kleineberg, U.; Moshammer, R.; Kling, M. F.

    2014-06-01

    The dissociative ionization of N2O by near-single-cycle laser pulses is studied using phase-tagged ion-ion coincidence momentum imaging. Carrier-envelope phase (CEP) dependences are observed in the absolute ion yields and the emission direction of nearly all ionization and dissociation pathways of the triatomic molecule. We find that laser-field-driven electron recollision has a significant impact on the dissociative ionization dynamics and results in pronounced CEP modulations in the dication yields, which are observed in the product ion yields after dissociation. The results indicate that the directional emission of coincident {{N}^{+}} and N{{O}^{+}} ions in the denitrogenation of the dication can be explained by selective ionization of oriented molecules. The deoxygenation of the dication with the formation of coincident N_{2}^{+} + {{O}^{+}} ions exhibits an additional shift in its CEP dependence, suggesting that this channel is further influenced by laser interaction with the dissociating dication. The experimental results demonstrate how few-femtosecond dynamics can drive and steer molecular reactions taking place on (much) longer time scales.

  2. Multiple climatic cycles imprinted on regional uplift-controlled fluvial terraces in the lower Yalong River and Anning River, SE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    He, Zexin; Zhang, Xujiao; Bao, Shuyan; Qiao, Yansong; Sheng, Yuying; Liu, Xiaotong; He, Xiangli; Yang, Xingchen; Zhao, Junxiang; Liu, Ru; Lu, Chunyu

    2015-12-01

    The development of fluvial systems on the southeastern margin of the Tibetan Plateau is linked to significant and rapid late Cenozoic uplift. The relatively complete fluvial terrace sequence preserved along the Yalong River valley and that of its tributary, the Anning River, provides an excellent archive for studying the development of terraces in rapidly uplifting mountainous areas. This study reveals that terrace development is predominantly controlled by multiscale climate cycles and long-term uplift, as shown by terrace dating, sedimentary characteristics, and incision rates. At least six alluvial terrace units were identified in 20 transverse sections through the terraces along about a 600 km length of river and were dated using Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL). The climatostratigraphic positions of the terrace deposits and their respective age constraints suggest that fluvial aggradation was concentrated during Marine Isotope Stages (MIS) 32, 22, 18, 4, 2, and the Younger Dryas (YD) and that incision occurred during the succeeding cold-to-warm transitions. The changes in fluvial style marked by terraces 6, 5, and 4 predominantly occurred in synchrony with the 100-ka Milankovitch climate cycles, while terraces 3 and 2 were controlled by the obliquity-driven 41-ka climate cycles. Finally, the aggradation of terrace T1 occurred in response to the YD stadial. During the intervening time between 0.72 and 0.063 Ma, terraces either did not form or were not preserved, which may suggest that uplift rates varied through time and influenced terrace formation/preservation. The progressive valley incision recorded by these fluvial terraces cannot be entirely explained by climate cycling alone. Temporal and spatial variations in incision rates indicate that the continuing long-term incision has been driven by uplift. The temporal distribution of the incision rates reveals two rapidly uplifting stages in the southeastern Tibetan

  3. Notch stimulates growth by direct regulation of genes involved in the control of glycolysis and the tricarboxylic acid cycle.

    PubMed

    Slaninova, Vera; Krafcikova, Michaela; Perez-Gomez, Raquel; Steffal, Pavel; Trantirek, Lukas; Bray, Sarah J; Krejci, Alena

    2016-02-01

    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

  4. 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

  5. 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.

  6. The Chlamydomonas Cell Cycle

    PubMed Central

    Cross, Frederick R.; Umen, James G.

    2015-01-01

    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 have 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 divisions, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth with 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 to 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. PMID:25690512

  7. Tbx2 Controls Lung Growth by Direct Repression of the Cell Cycle Inhibitor Genes Cdkn1a and Cdkn1b

    PubMed Central

    Lüdtke, Timo H-W.; Farin, Henner F.; Rudat, Carsten; Schuster-Gossler, Karin; Petry, Marianne; Barnett, Phil; Christoffels, Vincent M.; Kispert, Andreas

    2013-01-01

    Vertebrate organ development relies on the precise spatiotemporal orchestration of proliferation rates and differentiation patterns in adjacent tissue compartments. The underlying integration of patterning and cell cycle control during organogenesis is insufficiently understood. Here, we have investigated the function of the patterning T-box transcription factor gene Tbx2 in lung development. We show that lungs of Tbx2-deficient mice are markedly hypoplastic and exhibit reduced branching morphogenesis. Mesenchymal proliferation was severely decreased, while mesenchymal differentiation into fibrocytes was prematurely induced. In the epithelial compartment, proliferation was reduced and differentiation of alveolar epithelial cells type 1 was compromised. Prior to the observed cellular changes, canonical Wnt signaling was downregulated, and Cdkn1a (p21) and Cdkn1b (p27) (two members of the Cip/Kip family of cell cycle inhibitors) were strongly induced in the Tbx2-deficient lung mesenchyme. Deletion of both Cdkn1a and Cdkn1b rescued, to a large degree, the growth deficits of Tbx2-deficient lungs. Prolongation of Tbx2 expression into adulthood led to hyperproliferation and maintenance of mesenchymal progenitor cells, with branching morphogenesis remaining unaffected. Expression of Cdkn1a and Cdkn1b was ablated from the lung mesenchyme in this gain-of-function setting. We further show by ChIP experiments that Tbx2 directly binds to Cdkn1a and Cdkn1b loci in vivo, defining these two genes as direct targets of Tbx2 repressive activity in the lung mesenchyme. We conclude that Tbx2-mediated regulation of Cdkn1a and Cdkn1b represents a crucial node in the network integrating patterning information and cell cycle regulation that underlies growth, differentiation, and branching morphogenesis of this organ. PMID:23341776

  8. Climatic Controls on Fluvial Cut-and-Fill Cycles in Drainages with In-stream Wetlands in the Central Andes

    NASA Astrophysics Data System (ADS)

    Rech, J. A.; Latorre, C.

    2004-12-01

    Fluvial systems that possess in-stream wetlands, or marshes, are common in arid environments where water-tables are emergent and large discharge events uncommon. These streambeds are protected from erosion by a dense cover of hydrophyllic and phreatophytic vegetation. Along the Pacific slope of the Central Andes in northern Chile (~20°-26°S), which includes some of the driest sectors of the Atacama Desert, in-stream wetlands occur in deeply incised bedrock canyons on the Andean slope and piedmont. Over the last several years we have compiled a detailed record of late Pleistocene and Holocene vegetation changes along the Pacific slope of the Andes through the collection, analysis, and radiocarbon determination of over 180 rodent middens. Rodent middens record past changes in precipitation levels by tracking the downslope migrations of plant species into the hyperarid desert. We have also assembled a record of the cut-and-fill cycles of several fluvial systems with in-stream wetlands located at various distances (5-50 km) from the zone of ground-water recharge in the High Andes through stratigraphic mapping and the radiocarbon dating of over 100 samples of organic material within these wetlands. Combined, this well-dated record of hillslope vegetation and stream aggradation and incision allows us to assess the influence of climatic change on stream processes, including the nature of stream response, the sensitivity of different stream systems to climatic change, and the response times of streams to climate changes that vary in distance from ground-water recharge zones. The combined data set shows that in-stream wetland aggradation is directly linked to changes in climate, with aggradation occurring during wetter climatic periods when water tables are high. Incision occurs during dry climatic periods when water tables are lower and streambed sediments are no longer anchored by dense vegetation. Streams that are closer to ground-water recharge zones are more

  9. Cycle Analysis

    Energy Science and Technology Software Center (ESTSC)

    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

  10. 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

  11. 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

  12. Survival of anesthetized Sus scrofa after cycling (7-second on/3-second off) exposures to an electronic control device for 3 minutes.

    PubMed

    Jauchem, James R; Seaman, Ronald L; Fines, David A

    2011-06-01

    Electronic control devices (ECDs) may eventually be deployed by the military in a manner resulting in longer exposures than those encountered during law-enforcement operations. In a previous study, 18 repeated cycling (5-second on/5-second off) exposures (within a 3-minute period) of anesthetized swine to an ECD (TASER International's Advanced TASER X26 device) resulted in leg muscle contraction, acidosis, and increases in blood electrolytes. In the current study, experiments were performed to examine effects of exposures to a different cycling rate (7-second on/3-second off), from a modified X26 ECD, on 10 swine (Sus scrofa), maintained on propofol anesthesia. In contrast with the previous study, a large number of animals (6/10) died immediately after the exposures. There were no major differences in pre-exposure blood factors from survivors versus nonsurvivors, with the exception of hematocrit and 2 isoenzymes of lactate dehydrogenase. It is doubtful that these factors would be useful in predicting survival after ECD exposure. Blood pH was significantly decreased after exposure, but (in animals that survived) subsequently returned to baseline levels. On the basis of the overall survival rate, further development of useful ECDs (for long-term incapacitation during military operations) may require consideration of longer pauses between repeated exposures over a 3-minute period. PMID:21464698

  13. 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. PMID:27163342

  14. Successful use of "Hour 1" transfer of sperm microinjected oocytes in natural cycles of poor responder women: a prospective randomized controlled pilot study.

    PubMed

    Aragona, Cesare; Linari, Antonella; Micara, Giulietta; Tranquilli, Daniela; Gambaro, Agnese Maria Lourdes; Bezerra Espinola, Maria Salome

    2016-05-01

    The aim of the study is to demonstrate the successful use of "Hour 1" transfer of sperm microinjected oocytes in natural cycles of poor responder women. Seventy women were selected from 92 consecutive poor responders undergoing intracytoplasmatic sperm injection (ICSI) in a natural cycle at our Sterility and Assisted Reproduction Unit from September 2009 to July 2013, and randomly distributed in two homogeneous groups: Group A or B. Women in Group A (35) underwent transfer within 1 h after ICSI; Group B (35, control group) underwent transfer 3 days after ICSI. In Group A, seven clinical pregnancy and one miscarriage occurred; in Group B, eight clinical pregnancies and two miscarriages were observed. Pregnancy, miscarriage, term pregnancy and overall live birth rates' difference between the two groups was not statistically significant (p > 0.05). Difference between the two groups in terms of timing, type of delivery and newborn birthweight was not observed. Neither ectopic pregnancy nor multiple pregnancies occurred. "Hour 1" uterine transfer of ICSI oocytes, still to be considered with caution because of the relatively low number of observations of the pilot study, deserves further attention on a larger scale, and might be evaluated for clinical and financial effectiveness in other clinical settings. PMID:26654862

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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

  20. Cycling injuries.

    PubMed Central

    Cohen, G. C.

    1993-01-01

    Bicycle-related injuries have increased as cycling has become more popular. Most injuries to recreational riders are associated with overuse or improper fit of the bicycle. Injuries to racers often result from high speeds, which predispose riders to muscle strains, collisions, and falls. Cyclists contact bicycles at the pedals, seat, and handlebars. Each is associated with particular cycling injuries. Images Figure 1 Figure 3 Figure 4 Figure 5 PMID:8471908

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Helium process cycle

    DOEpatents

    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.

  8. Helium process cycle

    DOEpatents

    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.

  9. 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

  10. 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

  11. 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…

  12. 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

  13. 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

  14. 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

  15. Myb-Binding Protein 1A (MYBBP1A) Is Essential for Early Embryonic Development, Controls Cell Cycle and Mitosis, and Acts as a Tumor Suppressor

    PubMed Central

    Mori, Silvia; Bernardi, Rosa; Laurent, Audrey; Resnati, Massimo; Crippa, Ambra; Gabrieli, Arianna; Keough, Rebecca; Gonda, Thomas J.; Blasi, Francesco

    2012-01-01

    MYBBP1A is a predominantly nucleolar transcriptional regulator involved in rDNA synthesis and p53 activation via acetylation. However little further information is available as to its function. Here we report that MYBBP1A is developmentally essential in the mouse prior to blastocyst formation. In cell culture, down-regulation of MYBBP1A decreases the growth rate of wild type mouse embryonic stem cells, mouse embryo fibroblasts (MEFs) and of human HeLa cells, where it also promotes apoptosis. HeLa cells either arrest at G2/M or undergo delayed and anomalous mitosis. At mitosis, MYBBP1A is localized to a parachromosomal region and gene-expression profiling shows that its down-regulation affects genes controlling chromosomal segregation and cell cycle. However, MYBBP1A down-regulation increases the growth rate of the immortalized NIH3T3 cells. Such Mybbp1a down-regulated NIH3T3 cells are more susceptible to Ras-induced transformation and cause more potent Ras-driven tumors. We conclude that MYBBP1A is an essential gene with novel roles at the pre-mitotic level and potential tumor suppressor activity. PMID:23056166

  16. “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

  17. 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.

  18. 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.

  19. Urea Cycle Disorders.

    PubMed

    Kleppe, Soledad; Mian, Asad; Lee, Brendan

    2003-07-01

    Urea cycle disorders comprise a group of inborn errors of metabolism that represent unique gene-nutrient interactions whose significant morbidity arises from acute and chronic neurotoxicity associated with often massive hyperammonemia. Current paradigms of treatment are focused on controlling the flux of nitrogen transfer through the hepatic urea cycle by a combination of dietary and pharmacologic approaches. Evolving paradigms include the development of cell and gene therapies. Current research is focused on understanding the pathophysiology of ammonia-mediated toxicity and prevention of neural injury. PMID:12791198

  20. 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

  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. Comparison of the GnRH agonist and antagonist protocol on the same patients in assisted reproduction during controlled ovarian stimulation cycles.

    PubMed

    Lai, Qiaohong; Zhang, Hanwang; Zhu, Guijing; Li, Yufeng; Jin, Lei; He, Long; Zhang, Zhijun; Yang, Ping; Yu, Qilin; Zhang, Shu; Xu, Jun-Fa; Wang, Cong-Yi

    2013-01-01

    Despite the fact that both gonadotropin-releasing hormone (GnRH) agonist and antagonist protocol are effective in suppressing the incidence of premature luteinizing hormone (LH) surges through reversibly blocking the secretion of pituitary gonadotropins, the exact impact of these two distinctive protocols on the clinical setting of patients for in vitro fertilization and embryo transfer (IVF-ET) treatment, however, remained controversial. We thus in the present report conducted a retrospective study to compare the impact of GnRH agonist and antagonist protocol on the same patients during controlled ovarian stimulation cycles. A total of 81 patients undergoing 105 agonist and 88 antagonist protocol were analyzed. We failed to detect a significant difference between two protocols for the difference in duration of ovarian stimulation, number of recombinant FSH (Gonal-F) ampoules used, number of oocytes retrieved, serum levels for estradiol (E2) and progestone (P), thickness of endometrium, and the zygote- and blastocyst-development rate. It is seemly that high quality embryo rate was higher in the antagonist protocol, but the data did not reach a statistical significance. Nevertheless, Implantation rate and clinical pregnancy rate were significantly higher in the antagonist protocol (10.64% and 30.26%, respectively) than that of the agonist protocol (5.26% and 15.82%, respectively). Our data also suggest that the GnRH antagonist protocol is likely to have the advantage for improving the outcome of pregnancy in those patients with a history of multiple failures for the IVF-ET treatment. PMID:24040457

  3. Long Range Interaction Between Protein Complexes in DNA Controls Replication and Cell Cycle Progression:. the Double Helix and Microtubules Behave like Elastically Braced Strings

    NASA Astrophysics Data System (ADS)

    Matsson, L.

    2001-09-01

    A nonstationary interaction model, that controls the gross behaviour of DNA replication and cell cycle progression, is derived in terms of manydody physics in a chemically open T cell. The model predicts a long range force F(φ) = - (κ/2) φ(1 - φ /N)(2 - φ /N) between the origin recognition complexes (ORCs) bound by DNA, φ being the number of ORCs, N the threshold for initiation, and κ the compressibility modulus in the lattice of ORCs which behaves like an elastically braced string. Initiation of DNA replication is induced by a switch of sign of F, from attraction (-) and assembly in the G1 phase (0 < φ < N), to repulsion (+) and partial disassembly in the S phase (N < φ < 2N), with release of licensing factors from pre-replication complexes (pre-RCs) and prevention of re-replication. Termination of replication is due to a vanishing of F at φ = 2N, when all primed replicons have been duplicated once, and F(0) = 0 corresponds to a resting cell in absence of a driving force at φ = 0. The switch of sign of F at φ = N also explains the dynamic instability in growing microtubules (MTs), as well as the switch in the interleukin-2 (IL2) interaction with its receptor in late G1, at the R-point, after which a T cell proceeds to replication without further exposure to IL2. Shape, slope and scale of the response curves derived agree well with data from dividing T cells and polymerizing MTs, the variable length of which is due to a nonlinear dependence on initial concentrations of guanosine-triphosphate (GTP) and tubulin dimers.

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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 ...

  10. 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. PMID:26500059

  11. An on-line optimisation of a SBR cycle for carbon and nitrogen removal based on on-line pH and Our: the role of dissolved oxygen control.

    PubMed

    Puig, S; Corominas, Ll; Traore, A; Colomer, J; Balaguer, M D; Colprim, J

    2006-01-01

    A pilot plant sequencing batch reactor (SBR) was applied in a wastewater treatment plant treating urban wastewater focused on carbon and nitrogen removal. From an initial predefined step-feed cycle definition, the evolution of the on-line monitored pH and calculated oxygen uptake rate (OUR) were analysed in terms of knowledge extraction. First, the aerobic phases of the SBR cycle were operated using an On/Off dissolved oxygen (DO) control strategy that concluded with a sinusoidal pH profile that made detecting the "ammonia valley" difficult. After changing to fuzzy logic control of the dissolved oxygen and by adding an air flow meter to the pilot plant, the pH evolution and on-line calculated OUR showed a clearer trend during the aerobic phases. Finally, a proposed algorithm for adjusting the aerobic phases of the SBR for carbon and ammonia removal is presented and discussed. PMID:16722067

  12. Effects of human cytomegalovirus major immediate-early proteins in controlling the cell cycle and inhibiting apoptosis: studies with ts13 cells.

    PubMed

    Lukac, D M; Alwine, J C

    1999-04-01

    The major immediate-early (MIE) gene of human cytomegalovirus (HCMV) encodes several MIE proteins (MIEPs) produced as a result of alternative splicing and polyadenylation of the primary transcript. Previously we demonstrated that the HCMV MIEPs expressed from the entire MIE gene could rescue the temperature-sensitive (ts) transcriptional defect in the ts13 cell line. This defect is caused by a ts mutation in TAFII250, the 250-kDa TATA binding protein-associated factor (TAF). These and other data suggested that the MIEPs perform a TAF-like function in complex with the basal transcription factor TFIID. In addition to the transcriptional defect, the ts mutation in ts13 cells results in a defect in cell cycle progression which ultimately leads to apoptosis. Since all of these defects can be rescued by wild-type TAFII250, we asked whether the MIEPs could rescue the cell cycle defect and/or affect the progression to apoptosis. We have found that the MIEPs, expressed from the entire MIE gene, do not rescue the cell cycle block in ts13 cells grown at the nonpermissive temperature. However, despite the maintenance of the cell cycle block, the ts13 cells which express the MIEPs are resistant to apoptosis. MIEP mutants, which have previously been shown to be defective in rescuing the ts transcriptional defect, maintained the ability to inhibit apoptosis. Hence, the MIEP functions which affect transcription appear to be separable from the functions which inhibit apoptosis. We discuss these data in the light of the HCMV life cycle and the possibility that the MIEPs promote cellular transformation by a "hit-and-run" mechanism. PMID:10074130

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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

  18. The Morphogenesis Checkpoint in Saccharomyces cerevisiae: Cell Cycle Control of Swe1p Degradation by Hsl1p and Hsl7p

    PubMed Central

    McMillan, John N.; Longtine, Mark S.; Sia, Rey A. L.; Theesfeld, Chandra L.; Bardes, Elaine S. G.; Pringle, John R.; Lew, Daniel J.

    1999-01-01

    In Saccharomyces cerevisiae, the Wee1 family kinase Swe1p is normally stable during G1 and S phases but is unstable during G2 and M phases due to ubiquitination and subsequent degradation. However, perturbations of the actin cytoskeleton lead to a stabilization and accumulation of Swe1p. This response constitutes part of a morphogenesis checkpoint that couples cell cycle progression to proper bud formation, but the basis for the regulation of Swe1p degradation by the morphogenesis checkpoint remains unknown. Previous studies have identified a protein kinase, Hsl1p, and a phylogenetically conserved protein of unknown function, Hsl7p, as putative negative regulators of Swe1p. We report here that Hsl1p and Hsl7p act in concert to target Swe1p for degradation. Both proteins are required for Swe1p degradation during the unperturbed cell cycle, and excess Hsl1p accelerates Swe1p degradation in the G2-M phase. Hsl1p accumulates periodically during the cell cycle and promotes the periodic phosphorylation of Hsl7p. Hsl7p can be detected in a complex with Swe1p in cell lysates, and the overexpression of Hsl7p or Hsl1p produces an effective override of the G2 arrest imposed by the morphogenesis checkpoint. These findings suggest that Hsl1p and Hsl7p interact directly with Swe1p to promote its recognition by the ubiquitination complex, leading ultimately to its destruction. PMID:10490630

  19. 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.

  20. Exo70 is transcriptionally up-regulated by hepatic nuclear factor 4α and contributes to cell cycle control in hepatoma cells

    PubMed Central

    Zhao, Yujie; Hou, Jihuan; Mi, Panying; Mao, Liyuan; Xu, Liang; Zhang, Youyu; Xiao, Li; Cao, Hanwei; Zhang, Wenqing; Zhang, Bing; Song, Gang; Hu, Tianhui; Zhan, Yan-yan

    2016-01-01

    Exo70, a member of the exocyst complex, is involved in cell exocytosis, migration, invasion and autophagy. However, the expression regulation and function of Exo70 in hepatocellular carcinoma are still poorly understood. In this study, we found Exo70 expression in human hepatoma cells was greatly reduced after knocking down hepatic nuclear factor 4α (HNF4α), the most important and abundant transcription factor in liver. This regulation occurred at the transcriptional level but not post-translational level. HNF4α transactivated Exo70 promoter through directly binding to the HNF4α-response element in this promoter. Cell cycle analysis further revealed that down-regulation of HNF4α and Exo70 was essential to berberine-stimulated G2/M cell cycle arrest in hepatoma cells. Moreover, knocking down either Exo70 or HNF4α induced G2/M phase arrest of hepatoma cells. Exo70 acted downstream of HNF4α to stimulate G2/M transition via increasing Cdc2 expression. Together, our results identify Exo70 as a novel transcriptional target of HNF4α to promote cell cycle progression in hepatoma, thus provide a basis for the development of therapeutic strategies for hepatocellular carcinoma. PMID:26848864

  1. 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.

  2. Comparative safety, efficacy, and cycle control of Lunelle monthly contraceptive injection (medroxyprogesterone acetate and estradiol cypionate injectable suspension) and Ortho-Novum 7/7/7 oral contraceptive (norethindrone/ethinyl estradiol triphasic). Lunelle Study Group.

    PubMed

    Kaunitz, A M; Garceau, R J; Cromie, M A

    1999-10-01

    An open-label, nonrandomized, parallel, controlled study compared the efficacy, safety, and cycle control of a new monthly injectable contraceptive containing 25 mg of medroxyprogesterone acetate (MPA) and 5 mg of estradiol cypionate (E2C) (MPA/E2C) (Lunelle Monthly Contraceptive Injection) with that of a norethindrone 0.5, 0.75, 1.0 mg/0.035 mg ethinyl estradiol (NET/EE) triphasic oral contraceptive (Ortho-Novum 7/7/7). At study enrollment, women chose either the injections or the oral contraceptive. A higher proportion of women in the NET/EE group (65.1%) than in the MPA/E2C group (48.7%) had used hormonal contraception during the month before the study (p < 0.01). Overall, 55.5% (434/782) of MPA/E2C users and 67.6% (217/321) of NET/EE users completed the 60-week trial. One-year contraceptive efficacy (13 cycles of 28 days) for MPA/E2C and NET/EE was based on 8008 and 3434 woman-cycles of use, respectively. During the first year, one pregnancy occurred in an NET/EE user for a life table rate of 0.3; no pregnancies occurred in users of MPA/E2C. One additional pregnancy in the NET/EE group occurred during the 15th treatment cycle. After the first treatment cycle, women in both groups experienced regular menses, with an average cycle length of 28 days in MPA/E2C users and 27 days in NET/EE users. Although MPA/E2C users were more likely to experience bleeding irregularities, only 2.5% (19/775) cited metrorrhagia as a reason for discontinuing treatment. The adverse events reported in both treatment groups are consistent with those expected with the use of combined hormonal contraceptives. Overall, the results of this first Phase III US clinical trial of MPA/E2C confirm this method's high contraceptive efficacy and safety, as shown in previous studies by the World Health Organization. These results suggest that a monthly combination injectable would represent a welcome new contraceptive option for women in the US. PMID:10640164

  3. 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

  4. 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

  5. The Arabidopsis Cell Division Cycle

    PubMed Central

    Gutierrez, Crisanto

    2009-01-01

    Plant cells have evolved a complex circuitry to regulate cell division. In many aspects, the plant cell cycle follows a basic strategy similar to other eukaryotes. However, several key issues are unique to plant cells. In this chapter, both the conserved and unique cellular and molecular properties of the plant cell cycle are reviewed. In addition to division of individual cells, the specific characteristic of plant organogenesis and development make that cell proliferation control is of primary importance during development. Therefore, special attention should be given to consider plant cell division control in a developmental context. Proper organogenesis depends on the formation of different cell types. In plants, many of the processes leading to cell differentiation rely on the occurrence of a different cycle, termed the endoreplication cycle, whereby cells undergo repeated full genome duplication events in the absence of mitosis and increase their ploidy. Recent findings are focusing on the relevance of changes in chromatin organization for a correct cell cycle progression and, conversely, in the relevance of a correct functioning of chromatin remodelling complexes to prevent alterations in both the cell cycle and the endocycle. PMID:22303246

  6. Solar Cycle 23: An Anomalous Cycle?

    NASA Astrophysics Data System (ADS)

    de Toma, G.; White, O. R.; Chapman, G. A.; Walton, S. R.; Preminger, D. G.; Cookson, A. M.

    2004-05-01

    We discuss the importance of solar cycle 23 as a magnetically simpler cycle and a variant from recent cycles. We see a significant decrease in sunspot activity in cycle 23 relative to cycle 22, but the strength of the total solar irradiance (TSI) cycle did not change significantly. The latest SOHO/VIRGO TSI time series is analyzed using new solar variability measures obtained from full-disk solar images made at the San Fernando Observatory and the MgII 280nm index. The TSI record for the period 1986 to the present is reproduced within about 130ppm RMS using only two indices representing photospheric and chromospheric sources of variability due to magnetic regions. This is in spite of the difference in magnetic activity between the two cycles. Our results show the continuing improvement in TSI measurements and surrogates containing information necessary to account for irradiance variability.

  7. Proceedings: 1990 fossil plant cycling conference

    SciTech Connect

    Not Available

    1991-12-01

    Fossil plant cycling continues to be a key issue for many electric utilities. EPRI's previous cycling workshops, held in 1983, 1985, and 1987, allowed utilities to benefit from collective industry experience in the conversion of baseload fossil units to cyclic operation. Continued improvements in equipment, retrofits, diagnostics, and controls were highlighted at the 1990 conference. The objective is to provide a forum for utility discussions of the cycling operation of fossil fuel power plants. Potomac Electric Power Company (PEPCO) hosted the 1990 EPRI Fossil Fuel Cycling Conference in Washington, DC, on December 4--6, 1990. More than 130 representatives from utilities, vendors, government agencies, universities, and industry associations attended the conference. Following the general session, technical sessions covered such topics as plant modifications, utility retrofit experience, cycling economics, life assessment, controls, environmental controls, and energy storage. Attendees also toured PEPCO's Potomac River generating station, the site of an earlier EPRI cycling conversion study.

  8. 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

  9. Beyond the Fe-P-redox connection: preferential regeneration of phosphorus from organic matter as a key control on Baltic Sea nutrient cycles

    NASA Astrophysics Data System (ADS)

    Jilbert, T.; Slomp, C. P.; Gustafsson, B. G.; Boer, W.

    2011-06-01

    Patterns of regeneration and burial of phosphorus (P) in the Baltic Sea are strongly dependent on redox conditions. Redox varies spatially along water depth gradients and temporally in response to the seasonal cycle and multidecadal hydrographic variability. Alongside the well-documented link between iron oxyhydroxide dissolution and release of P from Baltic Sea sediments, we show that preferential remineralization of P with respect to carbon (C) and nitrogen (N) during degradation of organic matter plays a key role in determining the surplus of bioavailable P in the water column. Preferential remineralization of P takes place both in the water column and upper sediments and its rate is shown to be redox-dependent, increasing as reducing conditions become more severe at greater water-depth in the deep basins. Existing Redfield-based biogeochemical models of the Baltic may therefore underestimate the imbalance between N and P availability for primary production, and hence the vulnerability of the Baltic to sustained eutrophication via the fixation of atmospheric N. However, burial of organic P is also shown to increase during multidecadal intervals of expanded hypoxia, due to higher net burial rates of organic matter around the margins of the deep basins. Such intervals may be characterized by basin-scale acceleration of all fluxes within the P cycle, including productivity, regeneration and burial, sustained by the relative accessibility of the water column P pool beneath a shallow halocline.

  10. Beyond the Fe-P-redox connection: preferential regeneration of phosphorus from organic matter as a key control on Baltic Sea nutrient cycles

    NASA Astrophysics Data System (ADS)

    Jilbert, T.; Slomp, C. P.; Gustafsson, B. G.; Boer, W.

    2011-01-01

    Patterns of regeneration and burial of phosphorus (P) in the Baltic Sea are strongly dependent on redox conditions. Redox varies spatially along water depth gradients and temporally in response to the seasonal cycle and multidecadal hydrographic variability. Alongside the well-documented link between iron oxyhydroxide dissolution and release of P from Baltic Sea sediments, we show that preferential remineralization of P with respect to carbon (C) and nitrogen (N) during degradation of organic matter plays a key role in determining the surplus of bioavailable P in the water column. Preferential remineralization of P takes place both in the water column and upper sediments and its rate is shown to be water-depth dependent, increasing with the severity of reducing conditions into the deep basins. Existing Redfield-based biogeochemical models of the Baltic may therefore underestimate the imbalance between N and P availability for primary production, and hence the vulnerability of the Baltic to sustained eutrophication via the fixation of atmospheric N. However, burial of organic P is also shown to increase during multidecadal intervals of expanded hypoxia, due to higher net burial rates of organic matter around the margins of the deep basins. Such intervals may be characterized by basin-scale acceleration of all fluxes within the P cycle, including productivity, regeneration and burial, sustained by the relative accessibility of the water column P pool beneath a shallow halocline.

  11. Integrati