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Sample records for generalized milankovitch cycles

  1. Generalized Milankovitch Cycles and Longterm Climatic Habitability

    CERN Document Server

    Spiegel, David S; Dressing, Courtney D; Scharf, Caleb A; Mitchell, Jonathan L

    2010-01-01

    Although the Earth's orbit is never far from circular, terrestrial planets around other stars might experience substantial changes in eccentricity that could lead to climate changes, including possible "phase transitions" such as the snowball transition (or its opposite). There is evidence that Earth has gone through at least one globally frozen, "snowball" state in the last billion years, which it is thought to have exited after several million years because global ice-cover shut off the carbonate-silicate cycle, thereby allowing greenhouse gases to build up to sufficient concentration to melt the ice. Due to the positive feedback caused by the high albedo of snow and ice, susceptibility to falling into snowball states might be a generic feature of water-rich planets with the capacity to host life. This paper has two main thrusts. First, we revisit one-dimensional energy balance climate models as tools for probing possible climates of exoplanets, investigate the dimensional scaling of such models, and introd...

  2. Glacial Cycles and Milankovitch Forcing

    CERN Document Server

    Raghuraman, Shiv Priyam

    2015-01-01

    Using a recent conceptual model of the glacial-interglacial cycles we present more evidence of Milankovitch cycles being the trigger for retreat and forming of ice sheets in the cycles. This model is based on a finite approximation of an infinite dimensional model which has three components: Budyko's energy balance model describing the annual mean temperatures at latitudes, Widiasih's ODE which describes the behavior of the edge of the ice sheet, and Walsh et al. who introduced a snow line to account for glacial accumulation and ablation zones. Certain variables in the model are made to depend on the Milankovitch cycles, in particular, the obliquity of the Earth's axis and the eccentricity of the Earth's orbit. We see as a result that deglaciation and glaciation do occur mostly due to obliquity and to some extent eccentricity.

  3. Interglacials, Milankovitch Cycles, and Carbon Dioxide

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    Marsh, Gerald E

    2010-01-01

    The existing understanding of interglacial periods is that they are initiated by Milankovitch cycles enhanced by rising atmospheric carbon dioxide concentrations. During interglacials, global temperature is also believed to be primarily controlled by carbon dioxide concentrations, modulated by internal processes such as the Pacific Decadal Oscillation and the North Atlantic Oscillation. Recent work challenges the fundamental basis of these conceptions.

  4. Uniformity of the upper Famennian Milankovitch cycle in China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Research on chemo-biostratigraphy reveals that the periodic fluctuation of Ce/La ratios in carbonate sequence may reflect Milankovitch 100 ka eccentricity cyclicity. The Ce/La curve of the upper Famennian of Huangmao (Guangxi) may be well correlated to that of Muhua (Guizhou) and of Mid-Tarim (Xinjiang). They correspond not only in curve-feature, but also in number of cycles. Huangmao and Mid-Tarim are now located 3 000 km apart, during the Devonian possibly they were located farther apart. This study proves that the simultaneous sedimentary record of Milankovitch eccentricity cycles with a recurrent interval of 100 ka may be traced at different long-range sites. These cycles simultaneously developed in different depositional settings among different facies suites as a result of regional to global climate forcing, thus supporting the Milankovitch Theory.

  5. Interglacials, Milankovitch Cycles, Solar Activity, and Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Gerald E. Marsh

    2014-01-01

    Full Text Available The existing understanding of interglacial periods is that they are initiated by Milankovitch cycles enhanced by rising atmospheric carbon dioxide concentrations. During interglacials, global temperature is also believed to be primarily controlled by carbon dioxide concentrations, modulated by internal processes such as the Pacific Decadal Oscillation and the North Atlantic Oscillation. Recent work challenges the fundamental basis of these conceptions.

  6. Interglacials, Milankovitch Cycles, Solar Activity, and Carbon Dioxide

    OpenAIRE

    Marsh, Gerald E.

    2014-01-01

    The existing understanding of interglacial periods is that they are initiated by Milankovitch cycles enhanced by rising atmospheric carbon dioxide concentrations. During interglacials, global temperature is also believed to be primarily controlled by carbon dioxide concentrations, modulated by internal processes such as the Pacific Decadal Oscillation and the North Atlantic Oscillation. Recent work challenges the fundamental basis of these conceptions.

  7. Time-calibrated Milankovitch cycles for the late Permian.

    Science.gov (United States)

    Wu, Huaichun; Zhang, Shihong; Hinnov, Linda A; Jiang, Ganqing; Feng, Qinglai; Li, Haiyan; Yang, Tianshui

    2013-01-01

    An important innovation in the geosciences is the astronomical time scale. The astronomical time scale is based on the Milankovitch-forced stratigraphy that has been calibrated to astronomical models of paleoclimate forcing; it is defined for much of Cenozoic-Mesozoic. For the Palaeozoic era, however, astronomical forcing has not been widely explored because of lack of high-precision geochronology or astronomical modelling. Here we report Milankovitch cycles from late Permian (Lopingian) strata at Meishan and Shangsi, South China, time calibrated by recent high-precision U-Pb dating. The evidence extends empirical knowledge of Earth's astronomical parameters before 250 million years ago. Observed obliquity and precession terms support a 22-h length-of-day. The reconstructed astronomical time scale indicates a 7.793-million year duration for the Lopingian epoch, when strong 405-kyr cycles constrain astronomical modelling. This is the first significant advance in defining the Palaeozoic astronomical time scale, anchored to absolute time, bridging the Palaeozoic-Mesozoic transition.

  8. Milankovitch Cycles of Terrestrial Planets in Binary Star Systems

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    Forgan, Duncan H

    2016-01-01

    The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets. Habitable planets in binaries may therefore experience significant perturbations in orbit and spin. The direct effects of orbital resonances and secular evolution on the climate of binary planets remain largely unconsidered. We present latitudinal energy balance modelling of exoplanet climates with direct coupling to an N Body integrator and an obliquity evolution model. This allows us to simultaneously investigate the thermal and dynamical evolution of planets orbiting binary stars, and discover gravito-climatic oscillations on dynamical and secular timescales. We investigate the Kepler-47 and Alpha Centauri systems as archetypes of P and S type binary systems respectively. In the first case, Earthlike planets would experience rapid Milankovitch cycle...

  9. Milankovitch cycles of terrestrial planets in binary star systems

    Science.gov (United States)

    Forgan, Duncan

    2016-12-01

    The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets. Habitable planets in binaries may therefore experience significant perturbations in orbit and spin. The direct effects of orbital resonances and secular evolution on the climate of binary planets remain largely unconsidered. We present latitudinal energy balance modelling of exoplanet climates with direct coupling to an N-Body integrator and an obliquity evolution model. This allows us to simultaneously investigate the thermal and dynamical evolution of planets orbiting binary stars, and discover gravito-climatic oscillations on dynamical and secular time-scales. We investigate the Kepler-47 and Alpha Centauri systems as archetypes of P- and S-type binary systems, respectively. In the first case, Earth-like planets would experience rapid Milankovitch cycles (of order 1000 yr) in eccentricity, obliquity and precession, inducing temperature oscillations of similar periods (modulated by other planets in the system). These secular temperature variations have amplitudes similar to those induced on the much shorter time-scale of the binary period. In the Alpha Centauri system, the influence of the secondary produces eccentricity variations on 15 000 yr time-scales. This produces climate oscillations of similar strength to the variation on the orbital time-scale of the binary. Phase drifts between eccentricity and obliquity oscillations creates further cycles that are of order 100 000 yr in duration, which are further modulated by neighbouring planets.

  10. Milankovitch and sub-Milankovitch cycles of the Early Triassic Daye Formation, South China and their geochronological and paleoclimatic implications

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    Wu, H.; Zhang, S.; Feng, Q.; Jiang, G.; Li, H.; Yang, T.

    2011-12-01

    The most profound mass extinction in the Phanerozoic occurred at the end of the Permian, with global loss of nearly 90% of marine invertebrate species and 70% of terrestrial vertebrate genera. Recent studies suggested that volcanisms represented by the Siberian Trap were most likely cause of the end-Permian extinction. The post-extinction periods in the Early Triassic was characterized by low biodiversity, reduced abundance and size of invertebrates, hiatus in coal deposition, anomalously high sediment fluxes, and large perturbations of the carbon cycle, which have been interpreted as the consequence of persistently unfavorable environmental conditions. However, the time framework for the Early Triassic geological, biological and geochemical events is traditionally established by conodont biostratigraphy, but the absolute duration of condont biozones are not well constrained. In this study, a rock magnetic cyclostratigraphy, based on high-resolution analysis (2440 samples) of magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) intensity variations, was developed for the 55.1-m-thick, Early Triassic Daye Formation at the Daxiakou section, Hubei province in South China. The Daye Formation shows exceptionally well-preserved lithological cycles with alternations of thin-bedded mudstone, marl and limestone, which are closely tracked by the MS and ARM variations. Power spectral, wavelet and amplitude modulation (AM) analysis of the ARM and MS series reveal strong evidence for the presence of Milankovitch to sub-Milankovitch frequencies dominated by precession index signal and 4-5 ka cycles. Cycles expressed by variations in MS and ARM were likely controlled by the input of fine-grained detrital magnetite, which in turn may be driven by astronomically induced changes in monsoon intensity in the equatorial eastern Tethys during the Early Triassic greenhouse period. On the basis of the 100-ka tuning results, the astronomically constrained duration of

  11. Devonian Frasnian-Famennian Transitional Milankovitch Cycles and High-Resolution Stratigraphic Correlation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Four hierarchical cyclothems, superbundlesets, bundlesets,bundles and laminae, have been identified from the Devonian Frasnian-Famennian carbonate strata in Guangxi, South China. Their hierarchical structures, ratio relation ships and sequence in conodont zones are continuous and stable and can be traced across different facies zones and sedi mentary basins. Our data show that hierarchically organized superbundlesets, bundlesets, bundles and laminae correspond to the long eccentricity, eccentricity, obliquity or precession and sub-Milankovitch cycles respectively. Their periods were 400,000, 100,000, 33,333, 16,667 and 8,000-17,000 a, respectively. The ratios of long eccentricity to eccentricity, ec centricity to obliquity, and eccentricity to precession in the Devonian are 1:4, 1:3 and 1:6 respectively. Using these hier archical Milankovitch cyclothems, chronostratigraphical division and correlation can be realized at a resolution of 100 ka or 10 ka at the Frasnian-Famennian transition. The time intervals of the Upper rhenana Zone, linguiformis Zone, and the Lower, Middle and Upper triangularis Zone are 0.6, 0.8, 0.3, 0.3 and 0.3 Ma, respectively. Sea-level changes of the Frasnian-Famennian transition were not coherent and synchronous at the resolution of 100 ka or 10 ka in the basin-slope carbonate sequences of Guangxi, South China.

  12. “Concrete” Testimony to Milankovitch Cycle in Earth's changing obliquity

    Science.gov (United States)

    Fong Chao, Benjamin

    The present-day obliquity of the ecliptic of the Earth is γ = 23°26‧ 22″ and is decreasing by about 0″.5 a year. This article reports a “concrete” terrestrial testimony to this time variation, which plays a major part in the Milankovitch cycles.The obliquity is the angle between the equatorial plane, which is determined by Earth's rotation, and the ecliptic plane, defined as Earth's orbital plane around the Sun. It gives rise to the seasons; the two parallels of latitudee, the Tropic of Cancer in the Northern Hemisphere and the Tropic of Capricorn in the Southern Hemisphere, mark the limits of highest latitudes that the subsolar point reaches at solstices each year.

  13. Milankovitch cyclicity in modern continental margins: stratigraphic cycles in terrigenous shelf settings; El registro de la ciclicidad de Milankovitch en margenes continentales actuales: ciclos estratigraficos en plataformas terrigenas

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, F. J.; Ridente, D.

    2013-06-01

    We present a synthesis of the sedimentary responses to Late Quaternary Milankovitch-type sea-level cycles (100 and 20 kyr periodicities) as a basis for our investigations into the patterns and concepts of composite sequences in shallow-shelf settings. We describe the record of both 100 and 20 kyr cycles as documented worldwide and discuss the pattern of composite cyclicity mainly on the basis of previously published data from the Adriatic Sea and Gulf of Cadiz margins. Cycles of 100 kyr are those most frequently documented in Quaternary margins; they occur in the form of unconformity-bounded depositional sequences dominated by fairly uniform pro gradational-regressive units and more variable, though less well developed, transgressive deposits. Sequence boundaries correspond to prominent polygenic (regressive-transgressive) erosional surfaces that bear witness to considerable transgressive reworking of the original sub-aerial unconformity. Although the progradational units making up the greater part of these sequences have usually been interpreted as a record of a falling sea-level stage, recent evidence is pointing towards a more complex stratigraphic picture, including a distinction between relative highstand and lowstand deposits. The 20-kyr stratigraphic motifs show greater variation compared to that displayed by the more common 100-kyr sequences, particularly in the basic structure of systems tracts and the nature of bounding surfaces. The two case studies described here, the Adriatic Sea and Gulf of Cadiz margins, highlight the fact that, concomitantly with an increase in frequencies of cycles and sequences, sediment supply and the dynamics of their dispersal significantly affected the stratigraphic response to the main controlling factor, which was sea-level, thus determining the variety of expression in the 20 kyr cycles. (Author)

  14. Periodicity in a Conceptual Model of Glacial Cycles in the Absence of Milankovitch Forcing

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    Hahn, J.; Walsh, J.; Widiasih, E.; McGehee, R.

    2015-12-01

    Previously, McGehee and Widiasih coupled Budyko's Energy Balance Model with dynamics of a latitudinal ice-line incorporating the albedo feedback effect. They reduced this model to a two-dimensional equation of global mean temperature and a latitudinal ice-line. With this conceptual model, we now include dynamics of the ablation and accumulation of ice, to form a three-dimensional system that partitions the regions of the Earth latitudinally into an accumulation zone, ablation zone, and ice-free zone. Motivated by the findings of Abe-Ouchi et al that the fast retreat of ice-sheets is due to an increased rate of ablation via the effects of delayed isostatic rebound, we incorporate a simple switching mechanism to the model which increases the rate of ablation during periods of glacial retreat. This forms a discontinuous system of the Earth's temperature and ice-volume in which we find a stable periodic orbit. This can be interpreted as a intrinsic cycling of the Earth's climate in the absence of Milankovitch forcing.

  15. Recognition of Milankovitch Cycles in the Natural Gamma-Ray Logging of Upper Cretaceous Terrestrial Strata in the Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation (K2qn1) and Member 1 and 2 of the Nenjiang Formation (K2n1-2) of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities.The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ~7.55-8.62 cm/ka for the K2qn1 sections, and ~6.69-10.16 cm/ka for the K2n1-2 sections. Two marine transgression events occurred during the deposition of K2qn1 and K2n1-2 and their ages are at ~0.74-1.10 Ma and ~2.38-4.84 Ma, respectively. Identification of Milankovitch cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.

  16. The Upstream and Downstream impact of Milankovitch cycles in continental nonmarine sedimentary records

    Science.gov (United States)

    Valero, Luis; Garcés, Miguel; Huerta, Pedro; Cabrera, Lluís

    2016-04-01

    Discerning the effects of climate in the stratigraphic record is crucial for the comprehension of past climate changes. The signature of climate in sedimentary sequences is often assessed by the identification of Milankovitch cycles, as they can be recognized due to their (quasi) periodic behaviour. The integration of diverse stratigraphic disciplines is required in order to understand the different processes involved in the expression of the orbital cycles in the sedimentary records. New advances in Stratigraphy disclose the different variables that affect the sedimentation along the sediment routing systems. These variables can be summarized as the relationship between accommodation and sediment supply (AS/SS), because they account for the shifts of the total mass balance of a basin. Based in these indicators we propose a synthetic model for the understanding of the expression of climate in continental basins. Sedimentation in internally drained lake basins is particularly sensitive to net precipitation/evaporation variations. Rapid base level oscillations modify the AS/SS ratio sufficiently as to mask possible sediment flux variations associated to the changing discharge. On the other hand, basins lacking a central lacustrine system do not experience climatically-driven accommodation changes, and thus are more sensitive to archive sediment pulses. Small basins lacking carbonate facies are the ideal candidates to archive the impact of orbital forcing in the landscapes, as their small-scale sediment transfer systems are unable to buffer the upstream signal. Sedimentation models that include the relationship between accommodation and sediment supply, the effects of density and type of vegetation, and its coupled response with climate are needed to enhance their reliability.

  17. Links between annual, Milankovitch and continuum temperature variability.

    Science.gov (United States)

    Huybers, Peter; Curry, William

    2006-05-18

    Climate variability exists at all timescales-and climatic processes are intimately coupled, so that understanding variability at any one timescale requires some understanding of the whole. Records of the Earth's surface temperature illustrate this interdependence, having a continuum of variability following a power-law scaling. But although specific modes of interannual variability are relatively well understood, the general controls on continuum variability are uncertain and usually described as purely stochastic processes. Here we show that power-law relationships of surface temperature variability scale with annual and Milankovitch-period (23,000- and 41,000-year) cycles. The annual cycle corresponds to scaling at monthly to decadal periods, while millennial and longer periods are tied to the Milankovitch cycles. Thus the annual, Milankovitch and continuum temperature variability together represent the response to deterministic insolation forcing. The identification of a deterministic control on the continuum provides insight into the mechanisms governing interannual and longer-period climate variability.

  18. Milankovitch orbital cycles encoded by diagenetic iron sulfides in Neogene sediments, Stirone River section, Northern Apennines, Italy

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    Gunderson, K. L.; Kodama, K. P.; Anastasio, D. J.; Pazzaglia, F. J.

    2009-12-01

    We used rock magnetic parameters to identify Milankovitch orbital cycles in the marine sediments of the Messinian-Early Pleistocene Stirone River section, Northern Apennines, Italy. These measurements provide excellent proxies for subtle changes in depositional environment, including climate, in stratigraphic sections where facies variations are not evident. We measured 636 meters of section and collected samples every 1 meter, for which we measured magnetic susceptibility (MS), natural remanent magnetization (NRM), anhysteretic magnetization in a 40 mT peak alternating field(40mT ARM), and anhysteretic remanent magnetization in a 100 mT peak alternating field (100mT ARM). We present the results of our time-series analysis of the MS, 40mT ARM, and 100mT ARM stratigraphic series for 310 meters of section, encompassing the time period between 3.1 My and 1.8 My. During this time period, the power spectra produced from the MS stratigraphic series exhibits peaks with frequencies at 1/24m, 1/10m, and 1/6m. Based on our calculated mean sedimentation rate of 0.24 m/ky, we interpret the spectral peaks to be associated with the eccentricity, obliquity, and precessional orbital cycles, respectively. The 40mT ARM spectra exhibits peaks at similar periodicities, but the corresponding spectral peaks are broader and the spectral power is much lower. The 100mT ARM spectra shows an increase in spectral power with respect to the 40mT ARM, but it also exhibits broad spectral peaks. Low temperature (77 K) susceptibility (LT-MS) and isothermal remanent magnetization (IRM) acquisition experiments were conducted to determine which magnetic minerals carry the MS signal. The observed increase of the MS at low temperature (6-140%) was not large enough to conclude that the MS is dominated by paramagnetic grains. IRM acquisition modeling indicates two components of magnetization: (1) a major component comprising ~85% of the magnetization with a mean coercivity of 67 mT and (2) a minor

  19. Can Milankovitch orbital variations initiate the growth of ice sheets in a general circulation model?

    Science.gov (United States)

    Rind, D.; Peteet, D.; Kukla, G.

    1989-01-01

    The possibility of initiating the growth of ice sheets by solar insolation variations is examined. The study is conducted using a climate model with three different orbital configurations corresponding to 116,000 and 106,000 yr before the present and a modified insolation field with greater reductions in summer insolation at high northern latitudes. Despite the reduced summer and fall insolation, the model fails to maintain snow cover through the summer at locations of suspected ice sheet initiation. The results suggest that there is a discrepancy between the model's response to Milankovitch perturbations and the geophysical evidence of ice sheet initiation. If the model results are correct, the growth of ice shown by geophysical evidence would have occurred in an extremely ablative environment, demanding a complicated strategy.

  20. Lacustrine 87Sr/86Sr as a tracer to reconstruct Milankovitch forcing of the Eocene hydrologic cycle

    Science.gov (United States)

    Baddouh, M'bark; Meyers, Stephen R.; Carroll, Alan R.; Beard, Brian L.; Johnson, Clark M.

    2016-08-01

    The Green River Formation (GRF) provides one of the premier paleoclimate archives of the Early Eocene Climatic Optimum (∼50 Ma), representing the apex of the early Cenozoic greenhouse climate. Rhythmic lake-level variability expressed in the GRF has inspired numerous hypotheses for the behavior of the Eocene hydrologic cycle, including its linkage to astronomical forcing, solar variability, and the El Niño Southern Oscillation (ENSO). However, the lack of sufficient proxy data to document atmospheric water-mass transport and the geographic pattern of evaporation/precipitation/runoff has made it difficult to discriminate between different models for astronomical forcing. Variable 87Sr/86Sr ratios of bedrock that encompass the GRF provide an opportunity to reconstruct the spatial expression of the Eocene hydrologic cycle and its linkage to lake level. Here Sr isotope data from the Wilkins Peak Member, a rhythmic succession that has been demonstrated to record Milankovitch forcing of lake levels, indicate that high lake levels reflect an increased proportion of runoff from less radiogenic rocks west of the basin, eliminating a number of the existing astronomical-forcing hypotheses. The 87Sr/86Sr variability is consistent with a change in mean ENSO state, which is predicted by climate models to be linked to orbital-insolation. Thus, the 87Sr/86Sr data reveal a coupling of high frequency (ENSO) and low frequency (astronomical) climate variability, and also predict the existence of sizable astronomically-forced alpine snowpack during the last greenhouse climate. More broadly, this study demonstrates the utility of 87Sr/86Sr as a powerful tool for reconstructing the deep-time hydrologic cycle.

  1. Late cretaceous precessional cycles in double time: a warm-Earth milankovitch response.

    Science.gov (United States)

    Park, J; D'Hondt, S L; King, J W; Gibson, C

    1993-09-10

    Late Cretaceous climatic cycles are reflected in lithological and magnetic variations in carbonate sediments from South Atlantic Deep-Sea Drilling Project site 516F at a paleolatitude of roughly 30 degrees S. Magnetic susceptibility cycles 20 to 60 centimeters in length appear to be controlled by the precession of the equinoxes. Cyclicity is particularly robust within a 24-meter interval in the lower Campanian, where overtone spectral peaks are observed as well as secondary susceptibility maxima within individual precession cycles. One model for this behavior is that sedimentation in the narrow Cretaceous South Atlantic was controlled by equatorial climate dynamics, with the precessional insolation signal rectified by the large land masses surrounding the ocean basin.

  2. Recognition of Milankovitch cycles in the stratigraphic record:application of the CWT and the FFT to well-log data

    Institute of Scientific and Technical Information of China (English)

    YU Ji-feng; SUI Feng-gui; LI Zeng-xue; LIU Hua; WANG Yu-lin

    2008-01-01

    The authors applied a the combination of Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFF)methods to gamma ray well-log data from the Q3, G1 and D2 wells. This high-resolution stratigraphic study was based on Milankovitch's orbital cycle theory. It was found that the CWT scale factors, 'a,' of 12, 24 and 60 match the ratios of the periodicities of precession, obliquity and eccentricity very well. Nine intervals of the Permo-carboniferous strata were recognized to have Milankovitch cycles in them. For example, section A of well Q3 has 29 precession cycles, 15 obliquity cycles and 7 short eccentricity cycles. The wavelengths are 2.7, 4.4 and 7.8 m for precession, obliquity and eccentricity, respectively. Important geological parameters such as the stratigraphic completeness and the accumulation rate were also estimated. These results provide basic information for further cyclostratigraphic correlation studies in the area. They are of great significance for the study of ancient and future climate change.

  3. Milankovitch cycles in an equatorial delta from the Miocene of Borneo

    Science.gov (United States)

    Marshall, Nathan; Zeeden, Christian; Hilgen, Frederik; Krijgsman, Wout

    2017-08-01

    The factors controlling sedimentary cyclicity in deltaic systems are a subject of intense debate, and more research, in different deltaic environments and time periods, is needed to better understand the possible mechanisms. Offshore and Pleistocene case studies are more common than proximal and more ancient, greenhouse-climate examples. Furthermore, many studies lack a (statistical) cyclostratigraphic element. The paleo-Mahakam delta of Eastern Kalimantan, Borneo developed during the globally warm middle Miocene, in an equatorial setting, making it of interest to comprehend cyclic sedimentation in a period of warmer yet rapidly changing climate. In this study, statistical analysis of lithological changes shows that regular sandstone/shale alternations occur in a distinct pattern of cycles with thicknesses of ∼90, ∼30, and ∼17 m. Using independent dating, these thicknesses translate into periods of about 100, 40, and 20 kyr, matching the known periods of Earth's orbital eccentricity, obliquity and precession. The obliquity dominance in the middle interval is markedly similar to that observed in the global marine isotope (benthic δ18O) and other cyclic proxy records for this time interval. Despite a mismatch in the number of 40 kyr cycles compared to the global record that can be plausibly linked to the major sea-level drop at ∼13.8 Ma and facies shifts, it appears that the proximal setting of the paleo-Mahakam's sedimentation was dominantly controlled by allogenic orbital forcing, probably as a consequence of glacioeustasy. In particular, the observed obliquity dominance at paleo-equatorial latitudes, as seen in other records, highlights the dominance of orbital forcing, and potentially glacioeustatic sea level change, during this crucial period of warmer climate.

  4. Milankovitch radiation variations: a quantitative evaluation.

    Science.gov (United States)

    Shaw, D M; Donn, W L

    1968-12-13

    A quantitative determination of changes in the surface temperature caused by variations in insolation calculated by Milankovitch has been made through the use of the thermodynamic model of Adem. Under extreme conditions, mean coolings of 3.1 degrees and 2.7 degrees C, respectively, at latitudes 25 degrees and 65 degrees N are obtained for Milankovitch radiation cycles. At the sensitive latitude 65 degrees N, a mean cooling below the present temperature for each of the times of radiation minimum is only 1.4 degrees C. This result indicates that the Milankovitch effect is rather small to have triggered glacial climates.

  5. Proposed law of nature linking impacts, plume volcanism, and Milankovitch cycles to terrestrial vertebrate mass extinctions via greenhouse-embryo death coupling

    Science.gov (United States)

    Mclean, D. M.

    1994-01-01

    A greenhouse-physiological coupling killing mechanism active among mammals, birds, and reptiles has been identified. Operating via environmental thermal effects upon the maternal core-skin blood flow critical to the survival and development of embryos, it reduces the flow of blood to the uterine tract. Today, during hot summers, this phenomena kills embryos on a vast, global scale. Because of sensitivity of many mammals to modern heat, a major modern greenhouse could reduce population numbers on a global scale, and potentially trigger population collapses in the more vulnerable parts of the world. In the geological past, the killing mechanism has likely been triggered into action by greenhouse warming via impact events, plume volcanism, and Earth orbital variations (Milankovitch cycles). Earth's biosphere is maintained and molded by the flow of energy from the solar energy source to Earth and on to the space energy sink (SES). This SES energy flow maintains Earth's biosphere and its living components, as open, intermediate, dissipative, nonequilibrium systems whose states are dependent upon the rate of energy flowing through them. Greenhouse gases such as CO2 in the atmosphere influence the SES energy flow rate. Steady-state flow is necessary for global ecological stability (autopoiesis). Natural fluctuations of the C cycle such as rapid releases of CO2 from the mantle, or oceans, disrupt steady-state SES flow. These fluctuations constantly challenge the biosphere; slowdown of SES energy flow drives it toward thermodynamical equilibrium and stagnation. Fluctuations induced by impact event, mantle plume volcanism, and Milankovitch cycles can grow into structure-breaking waves triggering major perturbations of Earth's C cycle and mass extinctions. A major C cycle perturbation involves readjustment of the outer physiochemical spheres of the Earth: the atmosphere, hydrosphere, and lithosphere; and by necessity, the biosphere. A greenhouse, one manifestation of a major

  6. A ~400 ka supra-Milankovitch cycle in the Na, Mg, Pb, Ni, and Co records of a ferromanganese crust from the Vityaz fracture zone, central Indian ridge

    Directory of Open Access Journals (Sweden)

    R. Banerjee

    2010-07-01

    Full Text Available A ~400 ka (kilo years supra-Milankovitch cycle, recorded in the sodium, magnesium, lead, nickel and cobalt contents of a 32 mm thick ferromanganese crust from Vityaz fracture zone, central Indian ridge is reported here. To arrive at the geological ages, we used both 230Thexeccs and Co-chronometric datings. The correlation coefficient between the 230Thexeccs based dates and Co-chronometric dates for the top 0–8 mm is very high (r=0.9734, at 99.9% significance. The cobalt chronometric age for the bottom most oxide layer of this crust is computed as 3.5 Ma. Red-fit and multi-taper spectral analyses of time series data revealed the existence of the significant ~400 ka cycle, representing the changes in the hydrogeochemical conditions in the ocean due to the Earth's orbital eccentricity related summer insolation at the equator. This is the first report of such cycle from a hydrogenous ferromanganese crust from equatorial Indian ocean.

  7. Evidence for Milankovitch periodicities in Cenomanian-Turonian lithologic and geochemical cycles, western interior U.S.A.

    Science.gov (United States)

    Sageman, B.B.; Rich, J.; Arthur, M.A.; Birchfield, G.E.; Dean, W.E.

    1997-01-01

    The limestone/marlstone bedding couplets of the Bridge Creek Limestone Member, Cenomanian-Turonian Greenhorn Formation, were analyzed by applying spectral techniques to high-resolution lithologic and geochemical data from a core. The results suggest that the Bridge Creek contains a complex record of orbital cyclicity. The dominant signal appears to be obliquity, but signals corresponding to precession and eccentricity were also observed. The development of the bedding couplets is interpreted to have resulted from a combination of factors, including insolation-controlled changes in higher-latitude precipitation leading to dilution/redox cycles, and in lower-latitude evaporation, leading to changes in surface water conditions and productivity cycles in the calcareous plankton. The data interpreted to reflect redox cycles appear to be more strongly influenced by obliquity, and show a weak precessional signal. In contrast, trends in the carbonate record show the opposite response. The complex bedding pattern observed in the Bridge Creek Limestone is interpreted to result from the competing influences of different orbital cycles expressed through different pathways of the depositional system, and was also affected by changes in sedimentation rates related to relative sea level fluctuations, aperiodic dilution by volcanic ash, and changes in organic-matter production and redox conditions related to a global "oceanic anoxic event". These factors complicate cycle analysis in the lower part of the member but leave a relatively undisturbed record in the upper Bridge Creek Limestone. Copyright ?? 1997, SEPM (Society for Sedimentary Geology).

  8. Testing competing forms of the Milankovitch hypothesis

    DEFF Research Database (Denmark)

    Kaufmann, Robert K.; Juselius, Katarina

    2016-01-01

    We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical...... mechanisms postulated to drive glacial cycles. They show that the climate variables are driven partly by solar insolation, determining the timing and magnitude of glaciations and terminations, and partly by internal feedback dynamics, pushing the climate variables away from equilibrium. We argue...... that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: Internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land...

  9. PALEOCLIMATE: A Causality Problem for Milankovitch.

    Science.gov (United States)

    Karner, D B; Muller, R A

    2000-06-23

    According to the Milankovitch theory, changes in the incident solar radiation, called insolation, in the Northern Hemisphere provide the driving force for global glacial cycles. In their Perspective, Karner and Muller discuss recent studies of corals from around the world that shed doubt on the applicability of the theory to the termination of the penultimate glaciation. The authors argue that a fresh, unbiased look at the data is warranted.

  10. 大庆长垣姚家组高频层序地层与兰科维奇旋回对应性%Correspondence Between High Frequency Sequences and Milankovitch Cycles of Yaojia Formation in Daqing Piacanticline

    Institute of Scientific and Technical Information of China (English)

    孙阳; 樊太亮; 傅良同; 王海荣; 胡晓兰

    2011-01-01

    选取典型取心井对大庆长垣姚家组进行高频层序划分,共识别出98个超短期旋回,33个短期旋回,9个中期旋回和3个长期旋回.同时大庆长垣姚家组自然伽马曲线频谱分析结果表明,该地层中很好地保存了米兰科维奇旋回.其中,偏心率短周期引起的沉积旋回厚度为2.679~3.972 m,地轴倾角周期引起的沉积旋回厚度为1.379 ~2.131 m,岁差周期引起的沉积旋回厚度为0.601 ~0.901 m.高频层序与米兰科维奇旋回之间存在着较好的一致性,高频层序中期旋回、短期旋回和超短期旋回大致分别与米兰科维奇旋回的偏心率长周期、偏心率短周期以及岁差周期对应.地球轨道变化所引起的湖平面变化是高频层序形成的主控因素.%Ten typical well cores were observed to study high-frequency sequence classification of Daqing Yao-jia Formation in this paper. As a result, 98 ultra-short-term cycles, 33 short-term cycles, 9 mid-terra cycles and 3 long-term cycles were identified. Meanwhile, this paper analyzed the Milankovitch Cycles, based on the natural gamma curves of those wells. The result showed that Milankovitch Cycles were well preserved in the strata of Yaojia Formation. The thickness of long-period cycles caused by eccentricity ranges from 2. 679 m to 3. 972 m, the thickness of mid-period cycles caused by obliquity cycles ranges from 1. 379 m to 2. 131 m and the thickness of short-period cycles caused by precessions ranges from 0. 601 m to 0. 901 m. There is a good consistency between high-frequency sequences and Milankovitch Cycles. The mid-cycle, short-cycle and ultra-short-term cycles of high-frequency sequence are corresponding respectively to the long-period eccentricity, short-period eccentricity and the precession cycle of Milankovitch Cycles. Lake level change caused by the change of Earth's orbit is a major controlling factor of the formation of high-frequency sequences.

  11. 北黄海东部坳陷始新统米兰科维奇旋回特征%Characteristics of Milankovitch Cycle in Eocene Formation, Eastern Depression of the North Yellow Sea Basin

    Institute of Scientific and Technical Information of China (English)

    吴淑玉; 刘俊

    2015-01-01

    米兰科维奇旋回是记录在沉积地层中的表现形式,其代表的时间涵义是进行高分辨率地层划分和对比的有效手段,从地层中揭示的米兰科维奇旋回,可以完善地层学尤其是旋回地层学理论.以北黄海东部坳陷为研究对象,根据 J.Laskar 的解决方案计算出该区始新统的米兰科维奇旋回周期为:125 ka 和99 ka 的偏心率周期,51 ka 和39 ka 的地轴斜率周期,23 ka 和19 ka的岁差周期.通过对3口井的 GR(自然伽马)和 SP(自然电位)测井曲线进行频谱分析,发现其频谱峰值与天文周期存在着良好的对应关系,因此可以判定该区域地层中保存着完好的米兰科维奇沉积旋回.地层旋回厚度存在13.03~15.89 m 的长周期、3.70~5.21 m 的中周期和2.17~2.94 m 的短周期,并由此计算地层的沉积速率为121.20~127.12 m/Ma.从隆起沿着斜坡往湖盆中心,沉积持续时间越长且沉积厚度也越厚,但沉积速率相对稳定.通过连续小波变换对始新统地层进行小层划分,划分出6期沉积体,以每个沉积体为独立窗口进行频谱分析计算出沉积的持续时间和速率,从气候变化的影响分析每个阶段的沉积环境.从下往上层序地层 E6期为低水位体系域,E5和 E4为湖泊扩张体系域,E3为高位体系域,E2和 E1为湖泊收缩体系域.以上方法可以证明米兰科维奇进行沉积旋回分析是一种有效的方法.%Milankovitch cycle is the manifestation of sedimentary stratigraphy recorded,its time implication is an effective means of high resolution stratigraphic division and correlation,from the reservation information of Milankovitch cycles,which enrich stratigraphic theory,especially cyclostratigraphic theory.Characteristics of Milankovitch cycle in the eastern depression of the North Yellow Sea basin are explored in this study.Major parameters of Milankovitch cycle

  12. Testing competing forms of the Milankovitch hypothesis: A multivariate approach

    Science.gov (United States)

    Kaufmann, Robert K.; Juselius, Katarina

    2016-02-01

    We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical mechanisms postulated to drive glacial cycles. They show that the climate variables are driven partly by solar insolation, determining the timing and magnitude of glaciations and terminations, and partly by internal feedback dynamics, pushing the climate variables away from equilibrium. We argue that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship between solar insolation and a single climate variable are likely to suffer from omitted variable bias.

  13. Milankovitch rhythms in the Cretaceous: A GCM modelling study

    Science.gov (United States)

    Park, Jeffrey; Oglesby, Robert J.

    1991-10-01

    A major feature of the Cretaceous sedimentary record is the presence of cyclical bedding in carbonate sequences, many of which have periodicities similar to those of the Milankovitch rhythms of the earth-sun orbit. We used an atmospheric general circulation model, the NCAR CCM1, to investigate changes in the modeled Cretaceous atmospheric climate resulting from imposed Milankovitch orbital insolation changes. We extend a previous study using a 100 Ma mid-Cretaceous reconstruction to include perpetual-season (January and July) effects due to changes in obliquity as well as changes in precession. A total of eighteen pairs of insolation states have been examined. We perform a regression for linear sensitivity coefficients appropriate to precession and obliquity insolation changes, as well as compute a jackknife estimate of the coefficient uncertainty. Comparison of the regression residual to inherent model variability allows an estimate of any systematic but nonlinear model response to orbital insolation changes. Of particular importance is the response of the atmospheric hydrologic cycle. Changes in this cycle are consistent with at least three examples of Cretaceous bedding cycles: (1) The South Atlantic, where cyclical changes in the E- P balance with precession and, to a lesser extent, obliquity may account for regional oxic versus anoxic cycles observed in Cretaceous marine sediments cored from this region. (2) Regional changes in E- P over the east Tethys and adjacent continents with changes in insolation, which could induce changes in the production of oceanic deep water, possibly accounting for global occurrences of cyclic anoxic conditions. (3) Our simulations show a significant response of the hydrologic cycle to obliquity in July over western North America. This response, however, is smaller and more localized than those observed in low-latitude regions, and may not be robust to small changes in model boundary conditions. For most regions and modeled

  14. Calculation of denudation amount with Milankovitch cycle method: a case study in Biyang Sag%米氏旋回剥蚀量计算方法在泌阳凹陷的应用

    Institute of Scientific and Technical Information of China (English)

    姚益民; 徐旭辉; 刘翠荣; 谈彩萍; 罗家群; 朱景修

    2011-01-01

    The denudation thickness of Paleogene-Neogene unconformity in the Biyang Sag has been calculated with the Milankovitch cycle method. The calculation process has been divided into 2 steps. 1) Put the strata classification and logging curves of all formations as well as sections and sub-sections into "studies system of cyclostratigraphy" (version 1. 0) so as to find the 0. 405 Ma period. In this way? The maximum dominant cycle and the sedimentary time for available strata can be calculated. 2) Transform the denudation time besides of the above-mentioned sedimentary time for available strata into erosion thickness according to the 0. 405 Ma period. It has been concluded that in the center of the sag, onlyLiaozhuang Formation is denuded. In Anpeng area which locates in the southeast of the sag, the denudation thickness is less than 100 m and increases gradually to the west, northwest and northern margin of the sag, and finally exceeds 650 m around the missing boundary of Liaozhuang Formation. Hetaoyuan Formation is also denuded near to the sag boundary, mainly 4. 1 - 666. 5 m thick, and the total denudation thickness is over 1 000 m. The known oilfields in the sag mainly locate in the area with denudation thickness larger than 200 m.%利用米氏旋回地层学方法对泌阳凹陷古近系与新近系之间区域不整合面的剥蚀量进行了计算.泌阳凹陷古近系\\新近系剥蚀量计算可以分为2段:(1)各井各组(段和亚段)选定现有地层的分层和测井曲线数据进入“旋回地层学研究系统”(Version1.0),寻找0.405 Ma周期,求最大优势旋回,计算出现有沉积时间;(2)把现有地层沉积时间以外的剥蚀掉的时间,用0.405 Ma周期转化为剥蚀厚度.计算结果表明在凹陷的核心地区,仅廖庄组遭到剥蚀,凹陷东南部安棚一带剥蚀量小于100m,向凹陷西、西北以及北部边缘方向逐渐增大,至廖庄组缺失线附近,剥蚀厚度在650m以上.凹陷边缘附近,核桃园组也遭

  15. General framework for bridge life cycle design

    Institute of Scientific and Technical Information of China (English)

    Junhai MA; Airong CHEN; Jun HE

    2009-01-01

    Based on a detailed illustration for bridge life cycle design which comprises the processes of service life design, aesthetics design, performance design, environ-mental and ecological design, inspection, maintenance and repair design as well as cost analysis, this paper presented a general framework for bridge life cycle design comprising three design phases and six design processes.

  16. Optimal Orientations of the Generalized Cycles

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Optimal orientations of the generalized cycles are studied. For a graph G, let D(G) be the family of the strong orientations of G,d(G)=min{d(D)|D∈D(x)(G)} and ρ(G)=d(G)-d(G), where d(G) and d(D) are the diameters of G and D respectively. Evaluate the value of ρ(G) is evaluated by reduction to absurdity when G is a generalized cycle Cn([Km]), and a complete result is obtained.

  17. Generalizing Agile Software Development Life Cycle

    Directory of Open Access Journals (Sweden)

    S. Bhalerao

    2009-11-01

    Full Text Available In last decade, various agile methods have been introduced and used by software industry. It has been observed that many practitioners are using hybrid of agile methods and traditional methods. The knowledge of agile software development process about the theoretical grounds, applicability in large development settings and connections to establish software engineering disciplines remain mostly in dark. It has been reported that it is difficult for average manager to implement agile method in the organization. Further, every agile method has its own development cycle that brings technological, managerial and environmental changes in organization. A proper roadmap of agile software development in the form of agile software development life cycle can be developed to address the aforesaid issues of agile software development process. Thus, there is strong need of agile software development life cycle that clearly defines the phases included in any agile method and also describes the artifacts of each phase. This generalization of agile software development life cycle provides the guideline for average developers about usability, suitability, applicability of agile methods.

  18. Mending Milankovitch theory: obliquity amplification by surface feedbacks

    Directory of Open Access Journals (Sweden)

    C. R. Tabor

    2013-07-01

    Full Text Available Milankovitch theory states that orbitally induced changes in high-latitude summer insolation dictate the waxing and waning of ice-sheets. Accordingly, precession should dominate the ice-volume response because it most strongly modulates summer insolation intensity. However, Early Pleistocene (2.6–0.8 Ma ice-volume proxy records vary almost exclusively at the frequency of the obliquity cycle. To explore this paradox, we use an Earth system model coupled with a dynamic ice-sheet to separate the climate responses to idealized transient orbits of obliquity and precession that maximize insolation changes. Our results show that positive surface albedo feedbacks between high-latitude annual-mean insolation, ocean heat flux and sea-ice coverage, and boreal forest/tundra exchange enhance the ice-volume response to obliquity forcing relative to precession forcing. These surface feedbacks, in combination with modulation of the precession cycle power by eccentricity, may explain the dominantly 41 kyr cycles in global ice volume of the Early Pleistocene.

  19. Simulating sub-Milankovitch climate variations associated with vegetation dynamics

    OpenAIRE

    E. Tuenter; Weber, S.L.; F. J. Hilgen; Lourens, L. J.

    2006-01-01

    International audience; Climate variability at sub-Milankovitch periods (between 2 and 15 kyr) is studied in a set of transient simulations with a coupled atmosphere/ocean/vegetation model of intermediate complexity (Climber-2). Focus is on the region influenced by the African and Asian summer monsoon. Pronounced variations at sub-Milankovitch periods of about 10 kyr (Asia and Africa) and about 5 kyr (Asia) are found in the monsoonal runoff in response to the precessional forcing. This is cau...

  20. Milankovitch Modulated Eocene Growth Strata From the Jaca Piggyback Basin, Spanish Pyrenees

    Science.gov (United States)

    Anastasio, D. J.; Hinnov, L. A.; Newton, M. L.; Kodama, K. P.

    2005-12-01

    New stratigraphic and rock magnetic data from the southern margin of the Jaca basin, Spanish Pyrenees, shows evidence of Eocene sedimentary cycles modulated by the climatic effects of Milankovitch orbital forcing. Tectonic processes simultaneously controlled larger-scale stratigraphic sequences and overall wedge-top basin development. Within the context of existing magnetostratigraphy, we described 1 km of marine basinal and prodeltaic rocks near Pico del Aguila, a large-scale synsedimentary fold, and collected samples every ~4krs for ~4myrs for lithologic and rock magnetic analysis. In magnetochrons C17r, C18n.1n, and C18n.1r (1.27myrs) anhysteretic remanent magnetization (ARM) variations occur with strong hierarchical bundling patterns suggestive of precession-scale cycles grouped into 100 kyr eccentricity cycles, and "super bundled" into 400 kyr eccentricity cycles. This pattern was exploited to construct an "eccentricity time scale" for the series producing a minimally tuned time series that is 1.3 myrs in duration; comparing well with the magnetochron calibration. Spectral analysis of this ARM time series shows that the 100-kyr tuning has aligned power into all of the principal orbital frequency bands: long eccentricity (1/(400 kyrs)), obliquity (1/(40.4 kyrs)), long precession (1/(24.4 kyrs)), and short precession (1/(20 kyrs)). Lithologic data, including bed thickness and grain size also shows high frequency periodicity we attribute to precessional forcing. ARM variations may result from climate modulated carbonate production or more likely, variable detrital inputs such as atmospheric dust (varying wind intensity or aridity) or watershed erosion (runoff variation) rather than diagenetic sources. The Milankovitch based chronology within the growth stratigraphy was then used to calculate deformation rates. Tilt rates of 9 degrees / myr for folding are comparable to other studies in which deformation was averaged over more time. We show that Milankovitch

  1. Simulating sub-Milankovitch climate variations associated with vegetation dynamics

    Directory of Open Access Journals (Sweden)

    E. Tuenter

    2007-01-01

    Full Text Available Climate variability at sub-Milankovitch periods (between 2 and 15 kyr is studied in a set of transient simulations with a coupled atmosphere/ocean/vegetation model of intermediate complexity (CLIMBER-2. Focus is on the region influenced by the African and Asian summer monsoon. Pronounced variations at periods of about 10 kyr (Asia and Africa and about 5 kyr (Asia are found in the monsoonal runoff in response to the precessional forcing. In the model this is due to the following mechanism. For low summer insolation (precession maximum precipitation is low and desert expands at the expense of grass, while for high insolation (precession minimum precipitation is high and the tree fraction increases also reducing the grass fraction. This induces sub-Milankovitch variations in the grass fraction and associated variations in the water holding capacity of the soil. The runoff does not exhibit sub-Milankovitch variability when vegetation is kept fixed. High-latitude vegetation also exhibits sub-Milankovitch variability under both obliquity and precessional forcing. We thus hypothesize that sub-Milankovitch variability can occur due to the dynamic response of the vegetation. However, this mechanism should be further tested with more sophisticated climate/vegetation models.

  2. Planetary Hypothesis, sub-Milankovitch frequencies and Holocene cold events

    Science.gov (United States)

    Compagnucci, R. H.; Cionco, R. G.; Agosta, E.; Wanner, H.

    2013-05-01

    The Planetary Hypothesis of solar cycles proposes that the movement of the Sun around the solar system barycenter modulates the solar cycles at several times scales. Using a 3-D model of the solar system (Cionco and Compagnucci, 2012) we derived the solar barycentric motion and various dynamic parameters such as the angular momentum (L= Lx, Ly, Lz) for the Holocene. Angular momentum inversions are sporadic and important events in the dynamics of the MSB: Lz becomes negative and giant planets are nearly aligned. These episodes are related to some grand solar grand minima such as Maunder and Dalton, and also to the recent deep minimum 2007-2010 which was preceded by a Lz inversion in 1990. During the Holocene several negative Lz episodes occur that are grouped in approximately millennia to centuries long periods. Each group is separated by ~2000 years where the Lz values remain positive, both generating a cycle between 1500 and 2500 years. The spectral analysis shows significant peaks at sub-Milankovitch frequencies. Furthermore, the analysis of the spatiotemporal variability of temperature defined six specific cold events (8200, 6300, 4700, 2700, 1550 and 550 years BP) during the Holocene (Wanner et al, 2011). During, and /or before, of these major climates cooling, a group of negative Lz episodes were presented. Oppositely the resulted during the warms periods were the lack of the angular movement inversion together with the extremes of positive Lz . Therefore, the origin of Holocene cold events seems to be linked to the gravitational influence of the planets, that is to say the planetary torque that has a non-negligible effect on the causes of the solar magnetic cycle. Acknowledgements:The support of the Grants PID-UTN1351, UBACYT N_:20020100101049, CONICET PIP PIP 114-201001-00250 and MINCYT-MEYS ARC/11/09. References Cionco, R.G.; Compagnucci,R.H. (2012) Dynamical characterization of the last prolonged solar minima , Advances in Space Research 50(10), 1434

  3. A general property of non-endoreversible thermal cycles

    Energy Technology Data Exchange (ETDEWEB)

    Angulo-Brown, F.; Arias-Hernandez, L.A. [Instituto Politecnico Nacional (Mexico). Escuela Superior de Fisica y Matematicas; Paez-Hernandez, R. [Universidad Autonoma Metropolitana-Azcapotzalco (Mexico). Departamento de Ciencias Basicas

    1999-06-21

    In this work it is shown that a general property of endoreversible Curzon-Ahlborn-Novikov (CAN) cycles previously demonstrated can be extended for non-endoreversible CAN-cycles. This general property is based on the fact that at the so-called maximum ecological regime the efficiency is the average of the Carnot and the maximum-power efficiencies, and that in such a regime the power output is 75% of the maximum power of the CAN-cycle and the entropy produced is only 25% of that produced in the maximum power point. This property is independent of the heat transfer law. (author)

  4. Comment on "Glacial cycles drive variations in the production of oceanic crust".

    Science.gov (United States)

    Goff, John A

    2015-09-04

    Crowley et al. (Reports, 13 March 2015, p. 1237) propose that abyssal hill topography can be generated by variations in volcanism at mid-ocean ridges modulated by Milankovitch cycle-driven changes in sea level. Published values for abyssal hill characteristic widths versus spreading rate do not generally support this hypothesis. I argue that abyssal hills are primarily fault-generated rather than volcanically generated features.

  5. Extreme Climate Variations from Milankovitch-like Eccentricity Oscillations in Extrasolar Planetary Systems

    CERN Document Server

    Spiegel, David S

    2010-01-01

    Although our solar system features predominantly circular orbits, the exoplanets discovered so far indicate that this is the exception rather than the rule. This could have crucial consequences for exoplanet climates, both because eccentric terrestrial exoplanets could have extreme seasonal variation, and because giant planets on eccentric orbits could excite Milankovitch-like variations of a potentially habitable terrestrial planet,\\"A\\^os eccentricity, on timescales of thousands-to-millions of years. A particularly interesting implication concerns the fact that the Earth is thought to have gone through at least one globally frozen, "snowball" state in the last billion years that it presumably exited after several million years of buildup of greenhouse gases when the ice-cover shut off the carbonate-silicate cycle. Water-rich extrasolar terrestrial planets with the capacity to host life might be at risk of falling into similar snowball states. Here we show that if a terrestrial planet has a giant companion o...

  6. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    NARCIS (Netherlands)

    Lin, G.; Bruck, E.H.; Tegus, O.; Zhang, L.

    2004-01-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general performanc

  7. Plasticity-rigidity cycles: A general adaptation mechanism

    OpenAIRE

    Csermely, Peter

    2015-01-01

    Successful adaptation helped the emergence of complexity. Alternating plastic- and rigid-like states were recurrently considered to play a role in adaptive processes. However, this extensive knowledge remained fragmented. In this paper I describe plasticity-rigidity cycles as a general adaptation mechanism operating in molecular assemblies, assisted protein folding, cellular differentiation, learning, memory formation, creative thinking, as well as the organization of social groups and ecosys...

  8. On the Milankovitch orbital elements for perturbed Keplerian motion

    Science.gov (United States)

    Rosengren, Aaron J.; Scheeres, Daniel J.

    2014-03-01

    We consider sets of natural vectorial orbital elements of the Milankovitch type for perturbed Keplerian motion. These elements are closely related to the two vectorial first integrals of the unperturbed two-body problem; namely, the angular momentum vector and the Laplace-Runge-Lenz vector. After a detailed historical discussion of the origin and development of such elements, nonsingular equations for the time variations of these sets of elements under perturbations are established, both in Lagrangian and Gaussian form. After averaging, a compact, elegant, and symmetrical form of secular Milankovitch-like equations is obtained, which reminds of the structure of canonical systems of equations in Hamiltonian mechanics. As an application of this vectorial formulation, we analyze the motion of an object orbiting about a planet (idealized as a point mass moving in a heliocentric elliptical orbit) and subject to solar radiation pressure acceleration (obeying an inverse-square law). We show that the corresponding secular problem is integrable and we give an explicit closed-form solution.

  9. The fossil record as a tool in cyclo stratigraphy: the incidence of Milankovitch-scale palaeoenvironmental changes on palaeocommunities

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Tovar, F. J.

    2013-06-01

    Cyclo stratigraphic analysis at the Milankovitch scale has to date mainly been approached through the sedimentary record, although palaeontological data (the fossil record) is known to provide useful evidence of orbital-scale cycles of precession, obliquity and eccentricity. Orbit ally induced marine and terrestrial palaeoenvironmental changes determine variable responses on the part of the resident communities. Aside from the disruption of communities, complex evolutionary responses including stasis, speciation and extinction phenomena may take place. Cyclic variations in the marine past-biota at the community level, or in some particular taxa, have often been associated with orbit ally induced changes in palaeoenvironmental parameters. Cyclo stratigraphic research into foraminifera, radiol aria and nanno fossil data, mainly from Cretaceous sediments, may contribute significantly to our understanding of the planktonic community's response, whereas the response of the benthic community, deriving mainly from benthic foraminifera and trace fossils, has been studied to a lesser extent. Recognition of Milankovitch cycles from terrestrial palaeocommunities is relatively scarce and based mainly on the study of Pliocene-Miocene pollen assemblages. Astronomical forced climate changes determine well known variations in the distribution of terrestrial vegetation, but can also affect the terrestrial animal community, including hominid populations (migration, dispersion and colonisation). (Author)

  10. Maximum cycle work output optimization for generalized radiative law Otto cycle engines

    Science.gov (United States)

    Xia, Shaojun; Chen, Lingen; Sun, Fengrui

    2016-11-01

    An Otto cycle internal combustion engine which includes thermal and friction losses is investigated by finite-time thermodynamics, and the optimization objective is the maximum cycle work output. The thermal energy transfer from the working substance to the cylinder inner wall follows the generalized radiative law (q∝Δ (Tn)). Under the condition that all of the fuel consumption, the compression ratio and the cycle period are given, the optimal piston trajectories for both the examples with unlimited and limited accelerations on every stroke are determined, and the cycle-period distribution among all strokes is also optimized. Numerical calculation results for the case of radiative law are provided and compared with those obtained for the cases of Newtonian law and linear phenomenological law. The results indicate that the optimal piston trajectory on each stroke contains three sections, which consist of an original maximum-acceleration and a terminal maximum-deceleration parts; for the case of radiative law, optimizing the piston motion path can achieve an improvement of more than 20% in both the cycle-work output and the second-law efficiency of the Otto cycle compared with the conventional near-sinusoidal operation, and heat transfer mechanisms have both qualitative and quantitative influences on the optimal paths of piston movements.

  11. Milankovitch forcing of the last interglacial sea level.

    Science.gov (United States)

    Crowley, T J; Kim, K Y

    1994-09-09

    During the last interglacial, sea level was as high as present, 4000 to 6000 years before peak Northern Hemisphere insolation receipt 126,000 years ago. The sea-level results are shown to be consistent with climate models, which simulate a 3 degrees to 4 degrees C July temperature increase from 140,000 to 130,000 years ago in high latitudes, with all Northern Hemisphere land areas being warmer than present by 130,000 years ago. The early warming occurs because obliquity peaked earlier than precession and because precession values were greater than present before peak precessional forcing occurred. These results indicate that a fuller understanding of the Milankovitch-climate connection requires consideration of fields other than just insolation forcing at 65 degrees N.

  12. Time-dependent response of a zonally averaged ocean-atmosphere-sea ice model to Milankovitch forcing

    Energy Technology Data Exchange (ETDEWEB)

    Antico, Andres; Mysak, Lawrence A. [McGill University, Department of Atmospheric and Oceanic Sciences, Montreal, QC (Canada); Marchal, Olivier [Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA (United States)

    2010-05-15

    An ocean-atmosphere-sea ice model is developed to explore the time-dependent response of climate to Milankovitch forcing for the time interval 5-3 Myr BP. The ocean component is a zonally averaged model of the circulation in five basins (Arctic, Atlantic, Indian, Pacific, and Southern Oceans). The atmospheric component is a one-dimensional (latitudinal) energy balance model, and the sea-ice component is a thermodynamic model. Two numerical experiments are conducted. The first experiment does not include sea ice and the Arctic Ocean; the second experiment does. Results from the two experiments are used to investigate (1) the response of annual mean surface air and ocean temperatures to Milankovitch forcing, and (2) the role of sea ice in this response. In both experiments, the response of air temperature is dominated by obliquity cycles at most latitudes. On the other hand, the response of ocean temperature varies with latitude and depth. Deep water formed between 45 N and 65 N in the Atlantic Ocean mainly responds to precession. In contrast, deep water formed south of 60 S responds to obliquity when sea ice is not included. Sea ice acts as a time-integrator of summer insolation changes such that annual mean sea-ice conditions mainly respond to obliquity. Thus, in the presence of sea ice, air temperature changes over the sea ice are amplified, and temperature changes in deep water of southern origin are suppressed since water below sea ice is kept near the freezing point. (orig.)

  13. Zyklenuntersuchungen an unterkretazischen Sedimenten in NW-Deutschland : Nachweisbarkeit von Milankovitch-Zyklen

    OpenAIRE

    Nebe, Dirk W.

    1999-01-01

    Die Arbeit untersucht Sedimente der Unterkreide Nordwestdeutschlands auf mögliche zyklische Abfolgen. Dabei bildet der Nachweis von Milankovitch gesteuerten Sedimentationszyklen den Schwerpunkt der Untersuchungen. Die Zyklen werden mit Hilfe der Analyse der Sedimentfarbe und Gamma-Ray-Messungen an Bohrkernen analysiert. Im Rahmen der Arbeit wird ein spezielles Auswerteverfahren zur Ermittlung von Milankovitch-Zyklen zur unabhängigen Identifizierung und Bewertung der errechneten Zy...

  14. Generalized fish life-cycle poplulation model and computer program

    Energy Technology Data Exchange (ETDEWEB)

    DeAngelis, D. L.; Van Winkle, W.; Christensen, S. W.; Blum, S. R.; Kirk, B. L.; Rust, B. W.; Ross, C.

    1978-03-01

    A generalized fish life-cycle population model and computer program have been prepared to evaluate the long-term effect of changes in mortality in age class 0. The general question concerns what happens to a fishery when density-independent sources of mortality are introduced that act on age class 0, particularly entrainment and impingement at power plants. This paper discusses the model formulation and computer program, including sample results. The population model consists of a system of difference equations involving age-dependent fecundity and survival. The fecundity for each age class is assumed to be a function of both the fraction of females sexually mature and the weight of females as they enter each age class. Natural mortality for age classes 1 and older is assumed to be independent of population size. Fishing mortality is assumed to vary with the number and weight of fish available to the fishery. Age class 0 is divided into six life stages. The probability of survival for age class 0 is estimated considering both density-independent mortality (natural and power plant) and density-dependent mortality for each life stage. Two types of density-dependent mortality are included. These are cannibalism of each life stage by older age classes and intra-life-stage competition.

  15. Milankovitch-scale correlations between deeply buried microbial populations and biogenic ooze lithology

    Science.gov (United States)

    Aiello, I.W.; Bekins, B.A.

    2010-01-01

    The recent discoveries of large, active populations of microbes in the subseafloor of the world's oceans supports the impact of the deep biosphere biota on global biogeochemical cycles and raises important questions concerning the functioning of these extreme environments for life. These investigations demonstrated that subseafloor microbes are unevenly distributed and that cell abundances and metabolic activities are often independent from sediment depths, with increased prokaryotic activity at geochemical and/or sedimentary interfaces. In this study we demonstrate that microbial populations vary at the scale of individual beds in the biogenic oozes of a drill site in the eastern equatorial Pacific (Ocean Drilling Program Leg 201, Site 1226). We relate bedding-scale changes in biogenic ooze sediment composition to organic carbon (OC) and microbial cell concentrations using high-resolution color reflectance data as proxy for lithology. Our analyses demonstrate that microbial concentrations are an order of magnitude higher in the more organic-rich diatom oozes than in the nannofossil oozes. The variations mimic small-scale variations in diatom abundance and OC, indicating that the modern distribution of microbial biomass is ultimately controlled by Milankovitch-frequency variations in past oceanographic conditions. ?? 2010 Geological Society of America.

  16. Timing and response of vegetation change to Milankovitch forcing in temperate Australia and New Zealand

    Science.gov (United States)

    Dodson, J. R.

    1998-09-01

    In this study a comparison is made of the late Quaternary palaeovegetation records of the last 20,000 radiocarbon years from temperate Australia and New Zealand. The present vegetation is generally different in composition and structure but the broad patterns of vegetation structure follow generally well-defined climatic gradients. The number of records is small and dating of some sequences is imprecise but they suggest that the timing of vegetation changes in southeastern Australia and New Zealand appear to be broadly the same until the Holocene. There are no reliable published records from southwestern Australia until the Holocene. During the Holocene, the climate changes are less pronounced and the records diverge. The degree of change within southwestern Australia may be spatially inconsistent while peak warming in New Zealand appears to develop and finish ahead of southeastern Australia. A late Holocene cooling appears to only be present for upland areas of southeastern Australia. There appears to be no clear relationship between changing vegetation patterns and insolation gradients except around the Pleistocene-Holocene boundary. This was when both Summer and Winter latitudinal insolation gradients were at a maximum for the last 20,000 radiocarbon years. This corresponds to the time when the Westerlies were assumed to be consistently strong all year. For other periods the Milankovitch signal is either weak or vegetation change is predominantly driven by other factors.

  17. GENERAL: Reversible Carnot cycle outside a black hole

    Science.gov (United States)

    Deng, Xi-Hao; Gao, Si-Jie

    2009-03-01

    A Carnot cycle outside a Schwarzschild black hole is investigated in detail. We propose a reversible Carnot cycle with a black hole being the cold reservoir. In our model, a Carnot engine operates between a hot reservoir with temperature T1 and a black hole with Hawking temperature TH. By naturally extending the ordinary Carnot cycle to the black hole system, we show that the thermal efficiency for a reversible process can reach the maximal efficiency 1 - TH/T1. Consequently, black holes can be used to determine the thermodynamic temperature by means of the Carnot cycle. The role of the atmosphere around the black hole is discussed. We show that the thermal atmosphere provides a necessary mechanism to make the process reversible.

  18. Subsidence of the Laguna Salada Basin, northeastern Baja California, Mexico, inferred from Milankovitch climatic changes

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, Juan; Martin-Barajas, Arturo [Departamento de Geologia, CICESE, Ensenada Baja California (Mexico); Herguera, Juan Carlos [Division de Oceanologia, CICESE, Ensenada Baja California (Mexico)

    2005-01-15

    Laguna Salada in northern Baja California, Mexico, is an active half-graben product of the trans-tensional tectonics of the Gulf of California. It is sensitive to changes in sediment supply from the Colorado River basin. We present a time series analysis of the upper 980 m of a gamma-ray log from a borehole drilled near the Laguna Salada fault. The power spectrum of the gammaray log resembles the spectrum of {delta}{sup 1}8{omicron} Pleistocene isotopic variations from ice cores and from the deep ocean, known to be strongly controlled by Milankovitch cycles. We correlate {delta}{sup 1}8{omicron} stages with silty and sandy intervals in the log. Downcore ages for the last 780 ky are constrained within {approx}10 kyr. We derive a simple time vs. depth calibration relation for the basin over this time interval. Estimated sedimentation rates at the drill site appear to be constant with a value of {approx}1.6 mm/yr. We propose that this subsidence rate is produced by the Laguna Salada fault. [Spanish] La cuenca de Laguna Salada en el norte de Baja California, Mexico, es un semigraben activo producto de la tectonica ranstensional del Golfo de California. Esta cuenca endorreica es sensible a cambios en sedimentacion por variaciones en el aporte e sedimentos de fuentes cercanas y distales transportados por arroyos de las sierras adyacentes y por el Rio Colorado. Esta cuenca es un sitio excepcional para explorar el uso de cambios climaticos ciclicos como herramienta de datacion y estimar tasas de sedimentacion y subsidencia en el area. Para demostrar esto se presenta un analisis de series de tiempo de un registro de rayos de gama de un pozo geotermico exploratorio perforado adyacente a la falla de Laguna Salada, la cual limita el margen oriental de la cuenca. Los resultados del analisis indican que el espectro de los primeros 980 m del registro de rayos gama tiene una alta coherencia con el espectro de registros isotopicos paleoclimaticos de {delta}{sup 1}8{omicron} del

  19. D-brane networks in flux vacua, generalized cycles and calibrations

    Science.gov (United States)

    Evslin, Jarah; Martucci, Luca

    2007-07-01

    We consider chains of generalized submanifolds, as defined by Gualtieri in the context of generalized complex geometry, and define a boundary operator that acts on them. This allows us to define generalized cycles and the corresponding homology theory. Gauge invariance demands that D-brane networks on flux vacua must wrap these generalized cycles, while deformations of generalized cycles inside of a certain homology class describe physical processes such as the dissolution of D-branes in higher-dimensional D-branes and MMS-like instantonic transitions. We introduce calibrations that identify the supersymmetric D-brane networks, which minimize their energy inside of the corresponding homology class of generalized cycles. Such a calibration is explicitly presented for type II Script N = 1 flux compactifications to four dimensions. In particular networks of walls and strings in compactifications on warped Calabi-Yau's are treated, with explicit examples on a toroidal orientifold vacuum and on the Klebanov-Strassler geometry.

  20. D-brane networks in flux vacua, generalized cycles and calibrations

    CERN Document Server

    Evslin, J; Evslin, Jarah; Martucci, Luca

    2007-01-01

    We consider chains of generalized submanifolds, as defined by Gualtieri in the context of generalized complex geometry, and define a boundary operator that acts on them. This allows us to define generalized cycles and the corresponding homology theory. Gauge invariance demands that D-brane networks on flux vacua must wrap these generalized cycles, while deformations of generalized cycles inside of a certain homology class describe physical processes such as the dissolution of D-branes in higher-dimensional D-branes and MMS-like instantonic transitions. We introduce calibrations that identify the supersymmetric D-brane networks, which minimize their energy inside of the corresponding homology class of generalized cycles. Such a calibration is explicitly presented for type II N=1 flux compactifications to four dimensions. In particular networks of walls and strings in compactifications on warped Calabi-Yau's are treated, with explicit examples on a toroidal orientifold vacuum and on the Klebanov-Strassler geome...

  1. Generalized Short Pulse Equation for Propagation of Few-Cycle Pulses in Metamaterials

    CERN Document Server

    Pietrzyk, Monika E

    2016-01-01

    We show that propagation of ultrashort (few-cycle) pulses in nonlinear Drude metamaterials with both electric and magnetic Kerr nonlinearities is described by coupled generalized Short Pulse Equations. The resulting system of equations generalizes to the case of metamaterials both the Short Pulse Equation and its vector generalizations which describe the few-cycle pulses in dielectric optical fibers beyond the slowly varying envelope approximation leading to the nonlinear Schroedinger equation.

  2. Evolutionary consequences of changes in species' geographical distributions driven by Milankovitch climate oscillations.

    Science.gov (United States)

    Dynesius, M; Jansson, R

    2000-08-01

    We suggest Milankovitch climate oscillations as a common cause for geographical patterns in species diversity, species' range sizes, polyploidy, and the degree of specialization and dispersability of organisms. Periodical changes in the orbit of the Earth cause climatic changes termed Milankovitch oscillations, leading to large changes in the size and location of species' geographical distributions. We name these recurrent changes "orbitally forced species' range dynamics" (ORD). The magnitude of ORD varies in space and time. ORD decreases gradual speciation (attained by gradual changes over many generations), increases range sizes and the proportions of species formed by polyploidy and other "abrupt" mechanisms, selects against specialization, and favor dispersability. Large ORD produces species prone neither to extinction nor gradual speciation. ORD increases with latitude. This produces latitudinal patterns, among them the gradient in species diversity and species' range sizes (Rapoport's rule). Differential ORD and its evolutionary consequences call for new conservation strategies on the regional to global scale.

  3. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    Science.gov (United States)

    Beget, J. E.

    1993-01-01

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  4. Characterizing cycle-to-cycle variations of the shedding cycle in the turbulent wake of a normal flat plate using generalized phase averages

    Science.gov (United States)

    Martinuzzi, Robert

    2016-11-01

    Quasi-periodic vortex shedding in the turbulent wake of a thin-flat plate placed normal to a uniform stream at Reynolds number of 6700 is investigated based on Particle Image Velocimetry experiments. The wake structure and vortex formation are characterized using a generalized phase average (GPA), a refinement of the triple decomposition of Reynolds and Hussain (1970) incorporating elements of mean-field theory (Stuart, 1958). The resulting analysis highlights the importance of cycle-to-cycle variations in characterizing vortex formation, wake topology and the residual turbulent Reynolds Stresses. For example, it is shown that during high-amplitude cycles vorticity is strongly concentrated within the well-organized shed vortices, whereas during low-amplitude cycles the shed vortices are highly distorted resulting in significant modulation of the shedding frequency. It is found that high-amplitude cycles contribute more to the coherent Reynolds stress field while the low-amplitude cycles contribute to the residual stress field. It is further shown that traditional phase-averaging techniques lead to an over-estimation of the residual stress field. Natural Sciences and Engineering Research Council of Canada.

  5. Analysis of the effect of student cognizance of the learning cycle in general chemistry

    Science.gov (United States)

    Czapla, Matthew

    While the benefits of the using the Learning Cycle have been well researched, one area that has received surprisingly little investigation is the effect that student cognizance of the learning cycle has on student performance in chemistry. The Learning Cycle, with its strong theoretical roots in scientific practice and learning theory, offers a logical opportunity to educate students in the nature of science and metacognition. In addition, by examining the class holistically, students will have the opportunity to better link the lab and lecture components of the course. We hypothesized that since a keen understanding of the nature of science, strong metacognitive ability, and a holistic view of Learning Cycle classes have all been shown to increase student comprehension in general chemistry, students who were taught to understand the Learning Cycle would perform better than students who were not. Statistical analysis of survey and grade data will be presented.

  6. Performance characteristics of low-dissipative generalized Carnot cycles with external leakage losses

    Institute of Scientific and Technical Information of China (English)

    黄传昆; 郭君诚; 陈金灿

    2015-01-01

    Under the assumption of low-dissipation, a unified model of generalized Carnot cycles with external leakage losses is established. Analytical expressions for the power output and efficiency are derived. The general performance characteristics between the power output and the efficiency are revealed. The maximum power output and efficiency are calculated. The lower and upper bounds of the efficiency at the maximum power output are determined. The results obtained here are universal and can be directly used to reveal the performance characteristics of different Carnot cycles, such as Carnot heat engines, Carnot-like heat engines, flux flow engines, gravitational engines, chemical engines, two-level quantum engines, etc.

  7. Profit rate performance optimization for a generalized irreversible combined refrigeration cycle

    Indian Academy of Sciences (India)

    Kang Ma; Lingen Chen; Fengrui Sun

    2009-10-01

    Finite-time exergoeconomic performance of a Newtonian heat transfer law system generalized irreversible combined refrigeration cycle model with finite-rate heat transfer, heat leakage and internal irreversibility is presented in this paper. The operation of the generalized irreversible combined refrigeration cycle is viewed as a production process with exergy as its output. The performance optimization of the cycle is performed by taking profit as the objective. The optimal profit rate, optimal COP (coefficient of performance), as well as the relation between the optimal profit rate and COP of the cycle are derived. The focus of this paper is to obtain the compromise optimization between economics (profit rate) and the energy utilization factor (COP) for the cycle, by searching the optimum COP at maximum profit rate, which is termed as the finite time exergoeconomic performance bound. Moreover, the effects of various factors, including heat leakage, internal irreversibility and the price ratio, on the profit rate performance of the cycle are analysed by detailed numerical examples.

  8. Limit cycles in a generalized Gause-type predator-prey system

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The qualitative behavior of solutions for a generalized Game-type predator-prey system was studied.A large number of biologcal and bioeconomic models are special cases of this system. The system was investigated in the region D = { ( x, y) | x > 0, y > 0} because of the biological meaning of the system. The authors derived some sufficient conditions for the boundedness of the solutions and the existence of limit cycles of the system, which ensure that the system has at least one limit cycle. The theory of limit sets of autonomous plane systems and the theorem of cycle field of Poincare-Bendixson are efficiently employed in the research. The main results and their consequences presented not only generalize some known results, but also improve some corresponding results of other authors.

  9. PARADIGM IN THE PHILOSOPHY OF THE GENERAL THEORY OF CYCLES (CRISES

    Directory of Open Access Journals (Sweden)

    Laptev V. N.

    2014-06-01

    Full Text Available The article considers the special role of paradigms in the study (writing of the General theory of cycles. The authors ' task is systematization of knowledge in this area and obtain an objective assessment by means of retrospective material, which shows the change of one paradigm to another

  10. On the existence of cycles of every even length on generalized Fibonacci cubes

    Directory of Open Access Journals (Sweden)

    Norma Zagaglia Salvi

    1996-12-01

    Full Text Available A new topology for the interconnection of computing nodes in multiprocessors systems is the generalized Fibonacci cube.It can be embedded as a subgraph in the Boolean cube and it is also a supergraph of other structures. We prove that every edge of such a graph, but few initial cases, belongs to cycles of every even length.

  11. Self-organization in the Earth climate system versus Milankovitch-Berger astronomical cycles

    CERN Document Server

    Maslov, Lev A

    2014-01-01

    The Late Pleistocene Antarctic temperature variation curve is decomposed into two parts: cyclic and stochastic. These two parts represent different but tightly interconnected processes and also represent two different types of self-organization of the Earth climate system. The self-organization in the cyclic component is the non-linear auto-oscillation reaction of the Earth climate system, as a whole, to the input of solar radiation. The self-organization in the stochastic component is a nonlinear critical process, taking energy from, and fluctuating around the cyclic component of the temperature variations. The system of ODEs is written to model the cyclic part of the temperature variation, and the multifractal spectrum of the stochastic part of the temperature variation is calculated. The Earth climate can be characterized as an open, complex, self-organized dynamical system with nonlinear reaction to the input of solar radiation.

  12. Late Pliocene climate variability on Milankovitch to millennial time scales: a high-resolution study of MIS100 from the Mediterranean

    NARCIS (Netherlands)

    Becker, Julia; Lourens, L.J.; Hilgen, F.J.; Laan, Erwin van der; Kouwenhoven, T.J.; Reichart, G.-J.

    2005-01-01

    Astronomically tuned high-resolution climatic proxy records across marine oxygen isotope stage 100 (MIS100) from the Italian Monte San Nicola section and ODP Leg 160 Hole 967A are presented. These records reveal a complex pattern of climate fluctuations on both Milankovitch and sub-Milankovitch time

  13. The Milankovitch theory and climate sensitivity. I - Equilibrium climate model solutions for the present surface conditions. II - Interaction between the Northern Hemisphere ice sheets and the climate system

    Science.gov (United States)

    Neeman, Binyamin U.; Ohring, George; Joseph, Joachim H.

    1988-01-01

    A seasonal climate model was developed to test the climate sensitivity and, in particular, the Milankovitch (1941) theory. Four climate model versions were implemented to investigate the range of uncertainty in the parameterizations of three basic feedback mechanisms: the ice albedo-temperature, the outgoing long-wave radiation-temperature, and the eddy transport-meridional temperature gradient. It was found that the differences between the simulation of the present climate by the four versions were generally small, especially for annually averaged results. The climate model was also used to study the effect of growing/shrinking of a continental ice sheet, bedrock sinking/uplifting, and sea level changes on the climate system, taking also into account the feedback effects on the climate of the building of the ice caps.

  14. Quantum image encryption scheme with iterative generalized Arnold transforms and quantum image cycle shift operations

    Science.gov (United States)

    Zhou, Nanrun; Hu, Yiqun; Gong, Lihua; Li, Guangyong

    2017-06-01

    A new quantum image encryption scheme is suggested by using the iterative generalized Arnold transforms and the quantum image cycle shift operations. The times of the quantum image cycle shift operations are controlled by a hyper-chaotic sequence generated by a new 4D hyper-chaotic system. The image pixels are scrambled by the iterative generalized Arnold transform, and the values of the pixels are altered by the quantum image cycle shift operations. The four initial conditions of the new 4D hyper-chaotic system are exploited to control the two parameters, the iterative rounds of the generalized Arnold transform and the times of the quantum image cycle shift operations, respectively. Thus, the main keys of the proposed quantum image encryption scheme are the four initial conditions of the new 4D hyper-chaotic system and the key space is relatively large enough. Simulation results and theoretical analyses demonstrate that the proposed quantum image encryption scheme outperforms its classical counterparts apparently.

  15. The glacial cycles and cosmic rays

    CERN Document Server

    Kirkby, Jasper; Müller, R A

    2004-01-01

    The cause of the glacial cycles remains a mystery. The origin is widely accepted to be astronomical since paleoclimatic archives contain strong spectral components that match the frequencies of Earth's orbital modulation. Milankovitch insolation theory contains similar frequencies and has become established as the standard model of the glacial cycles. However, high precision paleoclimatic data have revealed serious discrepancies with the Milankovitch model that fundamentally challenge its validity and re-open the question of what causes the glacial cycles. We propose here that the ice ages are initially driven not by insolation cycles but by cosmic ray changes, probably through their effect on clouds. This conclusion is based on a wide range of evidence, including results presented here on speleothem growth in caves in Austria and Oman, and on a record of cosmic ray flux over the past 220 kyr obtained from the 10Be composition of deep-ocean sediments.

  16. Tracking the evolution of the disaster management cycle: A general system theory approach

    Directory of Open Access Journals (Sweden)

    Christo Coetzee

    2012-06-01

    Full Text Available Officials and scholars have used the disaster management cycle for the past 30 years to explain and manage impacts. Although very little understanding and agreement exist in terms of where the concept originated it is the purpose of this article to address the origins of the disaster management cycle. To achieve this, general system theory concepts of isomorphisms, equifinality, open systems and feedback arrangements were applied to linear disaster phase research (which emerged in the 1920s and disaster management cycles. This was done in order to determine whether they are related concepts with procedures such as emergency, relief, recovery and rehabilitation.

  17. Performance characteristics of low-dissipative generalized Carnot cycles with external leakage losses

    Science.gov (United States)

    Huang, Chuan-Kun; Guo, Jun-Cheng; Chen, Jin-Can

    2015-11-01

    Under the assumption of low-dissipation, a unified model of generalized Carnot cycles with external leakage losses is established. Analytical expressions for the power output and efficiency are derived. The general performance characteristics between the power output and the efficiency are revealed. The maximum power output and efficiency are calculated. The lower and upper bounds of the efficiency at the maximum power output are determined. The results obtained here are universal and can be directly used to reveal the performance characteristics of different Carnot cycles, such as Carnot heat engines, Carnot-like heat engines, flux flow engines, gravitational engines, chemical engines, two-level quantum engines, etc. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 11405032).

  18. The role of sub-milankovitch climatic forcing in the initiation of the northern hemisphere glaciation

    Science.gov (United States)

    Willis; Kleczkowski; Briggs; Gilligan

    1999-07-23

    Mechanisms responsible for the initiation of major glaciation in the Northern Hemisphere at about 2.75 million years ago are poorly understood. A laminated terrestrial sequence from Pula maar, Hungary, containing about 320,000 years in annual layers between 3.05 and 2. 60 million years ago, provides a detailed record of rates of climatic change across this dramatic transition. An analysis of the record implies that climatic variations at sub-Milankovitch frequencies (less than or equal to 15,000 years) were an important driving force during this transitional interval and that, as the threshold was approached, these increased in frequency and amplitude, possibly providing the final trigger for the amplification of Northern Hemisphere ice sheets.

  19. Influence of generalized focusing of few-cycle Gaussian pulses in attosecond pulse generation

    CERN Document Server

    Karimi, Ebrahim; Tosa, Valer; Velotta, Raffaele; Marrucci, Lorenzo

    2013-01-01

    In contrast to the case of quasi-monochromatic waves, a focused optical pulse in the few-cycle limit may exhibit two independent curved wavefronts, associated with phase and group retardations, respectively. Focusing optical elements will generally affect these two wavefronts differently, thus leading to very different behavior of the pulse near focus. As limiting cases, we consider an ideal diffractive lens introducing only phase retardations and a perfect non-dispersive refractive lens (or a curved mirror) introducing equal phase and group retardations. We study the resulting diffraction effects on the pulse, finding both strong deformations of the pulse shape and shifts in the spectrum. We then show how important these effects can be in highly nonlinear optics, by studying their role in attosecond pulse generation. In particular, the focusing effects are found to affect substantially the generation of isolated attosecond pulses in gases from few-cycle fundamental optical fields.

  20. The water cycle in the general circulation model of the martian atmosphere

    Science.gov (United States)

    Shaposhnikov, D. S.; Rodin, A. V.; Medvedev, A. S.

    2016-03-01

    Within the numerical general-circulation model of the Martian atmosphere MAOAM (Martian Atmosphere: Observation and Modeling), we have developed the water cycle block, which is an essential component of modern general circulation models of the Martian atmosphere. The MAOAM model has a spectral dynamic core and successfully predicts the temperature regime on Mars through the use of physical parameterizations typical of both terrestrial and Martian models. We have achieved stable computation for three Martian years, while maintaining a conservative advection scheme taking into account the water-ice phase transitions, water exchange between the atmosphere and surface, and corrections for the vertical velocities of ice particles due to sedimentation. The studies show a strong dependence of the amount of water that is actively involved in the water cycle on the initial data, model temperatures, and the mechanism of water exchange between the atmosphere and the surface. The general pattern and seasonal asymmetry of the water cycle depends on the size of ice particles, the albedo, and the thermal inertia of the planet's surface. One of the modeling tasks, which results from a comparison of the model data with those of the TES experiment on board Mars Global Surveyor, is the increase in the total mass of water vapor in the model in the aphelion season and decrease in the mass of water ice clouds at the poles. The surface evaporation scheme, which takes into account the turbulent rise of water vapor, on the one hand, leads to the most complete evaporation of ice from the surface in the summer season in the northern hemisphere and, on the other hand, supersaturates the atmosphere with ice due to the vigorous evaporation, which leads to worse consistency between the amount of the precipitated atmospheric ice and the experimental data. The full evaporation of ice from the surface increases the model sensitivity to the size of the polar cap; therefore, the increase in the

  1. Barriers and Facilitators for Generalizing Cycling Skills Learned at Camp to Home.

    Science.gov (United States)

    Temple, Viviene A; Purves, P Lynn; Misovic, Robyn; Lewis, Coral J; DeBoer, Carrie

    2016-01-01

    Many children with disabling conditions do not acquire the skills to successfully ride a 2-wheeled bicycle. The aim was to describe cycling patterns before and after an innovative learn-to-ride bike camp and factors that facilitate or hinder the generalization of skills developed at camp to home. Parents and children participated in semistructured interviews 3-4 mo postcamp. Transcripts were examined deductively for participation and contextual influences using a template of codes approach. None of the children were successfully riding a 2-wheeled bicycle before camp. Two patterns of participation were evident from narrative descriptions of postcamp riding: "riders" and "not there yet." Major facilitating factors were the camp itself, the interaction between the camp and the health service, and continued parent involvement. The program transferred well to home for children who were riding independently on the last day of camp. Ongoing support is needed for children "not there yet."

  2. A conceptual model for glacial cycles and the middle Pleistocene transition

    Science.gov (United States)

    Daruka, István; Ditlevsen, Peter D.

    2016-01-01

    Milankovitch's astronomical theory of glacial cycles, attributing ice age climate oscillations to orbital changes in Northern-Hemisphere insolation, is challenged by the paleoclimatic record. The climatic response to the variations in insolation is far from trivial. In general the glacial cycles are highly asymmetric in time, with slow cooling from the interglacials to the glacials (inceptions) and very rapid warming from the glacials to the interglacials (terminations). We shall refer to this fast-slow dynamics as the "saw-tooth" shape of the paleoclimatic record. This is non-linearly related to the time-symmetric variations in the orbital forcing. However, the most pronounced challenge to the Milankovitch theory is the middle Pleistocene transition (MPT) occurring about one million years ago. During that event, the prevailing 41 kyr glacial cycles, corresponding to the almost harmonic obliquity cycle were replaced by longer saw-tooth shaped cycles with a time-scale around 100 kyr. The MPT must have been driven by internal changes in climate response, since it does not correspond to any apparent changes in the orbital forcing. In order to identify possible mechanisms causing the observed changes in glacial dynamics, it is relevant to study simplified models with the capability of generating temporal behavior similar to the observed records. We present a simple oscillator type model approach, with two variables, a temperature anomaly and a climatic memory term. The generalization of the ice albedo feedback is included in terms of an effective multiplicative coupling between this latter climatic memory term (representing the internal degrees of freedom) and the external drive. The simple model reproduces the temporal asymmetry of the late Pleistocene glacial cycles and suggests that the MPT can be explained as a regime shift, aided by climatic noise, from a period 1 frequency locking to the obliquity cycle to a period 2-3 frequency locking to the same obliquity

  3. Correspondence Between Astronomical Periods and Sedimentary Cycles

    Institute of Scientific and Technical Information of China (English)

    Cheng Rihui; You Haitao

    2000-01-01

    It is shown from detailed study that there are some genetic relationships between outer events of celestial bodies and inner geological events of the earth, such as some kinds of correspondences between astronomical periods and sedimentary cycles. The time spans of movement periods of the solar system around the center of the galaxy and cross the plain of the galaxy, the periods of the earth orbit (Milankovitch period) and periods of sunspot are coincided with that of respective sedimentary cycles. It is suggested that the gravity and magnetic changes of the earth leading up to the global climatic and sea level changes are the dynamics of sedimentary cycles.

  4. A criterion for timescale decomposition of external inputs for generalized phase reduction of limit-cycle oscillators

    CERN Document Server

    Kurebayashi, Wataru; Nakao, Hiroya

    2015-01-01

    The phase reduction method is a dimension reduction method for weakly driven limit-cycle oscillators, which has played an important role in the theoretical analysis of synchro- nization phenomena. Recently, we proposed a generalization of the phase reduction method [W. Kurebayashi et al., Phys. Rev. Lett. 111, 2013]. This generalized phase reduction method can robustly predict the dynamics of strongly driven oscillators, for which the conventional phase reduction method fails. In this generalized method, the external input to the oscillator should be properly decomposed into a slowly varying component and remaining weak fluctua- tions. In this paper, we propose a simple criterion for timescale decomposition of the external input, which gives accurate prediction of the phase dynamics and enables us to systematically apply the generalized phase reduction method to a general class of limit-cycle oscillators. The validity of the criterion is confirmed by numerical simulations.

  5. The Housing Careers of Older Canadians: An Investigation Using Cycle 16 of the General Social Survey

    Directory of Open Access Journals (Sweden)

    Perks, Thomas

    2008-01-01

    Full Text Available EnglishIn this paper we use the Aging and Social Support Survey (GSS16 and the theoretical conception of a ‘housing career’ to identify the correlates of housing tenure (rent vs.own among Canadians age 45 and over. We draw on primarily US literature to isolate three general explanatory clusters (social support, health, and economic characteristics.Based on analyses using logistic regression, the results indicate that the majority of variation in housing tenure exists due to standard demographic and household characteristics. In fact, of the three focal explanatory clusters, only social support characteristics significantly enhance model fit beyond the baseline model, suggesting that the housing tenure of older Canadians hinges heavily on fairly standard characteristics.FrenchDans cet article, nous nous sommes servis de l’enquête « Vieillissement et soutien social» (ESG16 et de la théorie du cycle de vie du logement pour identifier les corrélatsdes modes d’occupation (location vs. propriétariat chez les canadiens âgés de 45 ans etplus. Nous avons principalement puisé la littérature des États-Unis pour isoler trois groupesexplicatifs généraux (caractéristiques: de support social, de santé, et économiques.Les résultats, basés sur des analyses de régression logistique, indiquent que la majoritédes variations dans les modes d’occupation peuvent être attribuées à des caractéristiquesdémographiques et économiques de base. En effet, des trois groupes explicatifs focaux, cesont seulement les caractéristiques de support social qui ont fait monter l’ajustement dumodèle en delà du modèle de base, ce qui suggère que les modes d’occupation des logementspour les canadiens d’un certain âge dépend beaucoup des caractéristiques de base.Mots clés: Cycle de vie du logement, modes d’occupation de logements, adultes âgés

  6. A response to "Milankovitch theory viewed from Devils Hole" by J. Imbrie, A.C. Mix and D.G. Martinson

    Science.gov (United States)

    Winograd, I.J.; Landwehr, J.M.

    1993-01-01

    The detailed and well-dated 500,000-yr record of oxygen-18 variations found in vein calcite core DH-11 taken from Devils Hole in Nevada provides several challenges to the Milankovitch theory for the occurrence of Quaternary glaciations. A recent discussion paper (Imbrie and others, 1993) has dismissed the relevance of this well-dated core for determining the timing of global climatic fluctuations and, moreover, asserts that the Devils Hole record provides support for the Milankovitch theory. Upon analysis of the arguments found in this discussion, the authors found nothing to dissuade them from the original conclusion that the Devils Hole chronology does present a serious challenge to the Milankovitch theory.

  7. Time-Correlative Recovery of Milankovitch-Scale Cyclicity From An Eocene Fluvial-Deltaic System, Southern Pyrenees, Spain

    Science.gov (United States)

    Anastasio, D. J.; Kodama, K. P.; Teletzke, A. L.; Boulton, S.; Bilardello, D.

    2012-12-01

    Given the controversial state of cyclostratigraphy and the important contributions it provides to the construction of the geologic time scale it is important to know what processes encode environmental changes and what data sets best preserve the integrity of the stratigraphic signal. We test cyclostratigraphy based on rock magnetic data to calibrate time at sub-magnetic chron scales to reconstruct a ~100 kilometer-long transect of an ancient fluvial-deltaic system. Rock magnetic data provides an objective record of multi-frequency cyclicity we interpret to be climate cycles preserved in the Tertiary Ainsa-Jaca-Pamplona Basins. Anhysteretic Remanent Magnetization (ARM) from rocks dominated with low coercivity magnetite and Fe-sulfides and Isothermal Remanent Magnetization (IRM) from rocks dominated by high coercivity hematite and goethite shows the potential to trace correlative beds from terrestrial watersheds to the deep marine basin across facies boundaries. The fluvial Escanilla Fm.-Campodarbe Gp. along the Eripol-Olson section varies from sheet sandstones and overbank siltstone to amalgamated gravels up-section, is 910 m long, records chrons C19r to C15n, and was deposited at a rate of 14cm/kyr. A modified S-ratio, which takes advantage of the differences in coercivities of goethite and hematite was used to assess relative mineral abundance and shows variations in the ratio of goethite : goethite + hematite concentrations around the frequencies expected for short eccentricity (~100 kyr) and obliquity (~40 kyr). A 5 T field saturation IRM (SIRM) was first applied followed by alternating field (af) demagnetization in a 100 mT field (=goethite + hematite concentration), followed by the application of a 1 T backfield and 100 mT af demagnetization (= goethite concentration only). The correlative deltaic Arguis Fm. section coarsens up section from a condensed middle-outer neritic glauconite sandstone and marl sequence to proximal prodeltaic shales and siltstones, to

  8. General Concerns Life-Cycle Design of Economical Ice-Resistant Structures in the Bohai Sea

    Directory of Open Access Journals (Sweden)

    Zhang Da-yong

    2017-08-01

    Full Text Available In China, the oil and natural gas resources of Bohai Bay are mainly marginal oil fields. It is necessary to build both iceresistant and economical offshore platforms. However, there are many risks during the life cycle of offshore platforms due to the imperfect preliminary design for the Bohai Sea economical ice-resistant structures. As a result, the whole life-cycle design should be considered, including plan, design, construction, management and maintenance design. Based on the demand of existing codes and research of the basic design, structural ice-resistant performance and the reasonable management and maintenance, the life-cycle design theory is discussed. It was concluded that the life-cycle cost-effective optimum design proposed will lead to a minimum risk.

  9. Limit Cycles and Bifurcation in Piecewise-Analytic Systems: 1. General Theory

    OpenAIRE

    Banks, S.P.; Khathur, Saadi. A.

    1989-01-01

    The existence of limit cycles and periodic doubling bifurcations in piecewise-linear and piecewise-analytic systems is studied. Some theoretical sufficient conditions are obtained directly in terms of the right hand sided of the system.

  10. Clustering in Cell Cycle Dynamics with General Response/Signaling Feedback

    CERN Document Server

    Young, Todd; Buckalew, Richard; Moses, Gregory; Boczko, Erik; 10.1016/j.jtbi.2011.10.002.

    2011-01-01

    Motivated by experimental and theoretical work on autonomous oscillations in yeast, we analyze ordinary differential equations models of large populations of cells with cell-cycle dependent feedback. We assume a particular type of feedback that we call Responsive/Signaling (RS), but do not specify a functional form of the feedback. We study the dynamics and emergent behaviour of solutions, particularly temporal clustering and stability of clustered solutions. We establish the existence of certain periodic clustered solutions as well as "uniform" solutions and add to the evidence that cell-cycle dependent feedback robustly leads to cell-cycle clustering. We highlight the fundamental differences in dynamics between systems with negative and positive feedback. For positive feedback systems the most important mechanism seems to be the stability of individual isolated clusters. On the other hand we find that in negative feedback systems, clusters must interact with each other to reinforce coherence. We conclude fr...

  11. Late Pliocene millennial to Milankovitch-scale climate variability: A case study of Marine Isotope Stages 101-95 in the Mediterranean and adjacent North Atlantic

    NARCIS (Netherlands)

    Becker, Julia

    2005-01-01

    The selected time interval and sections should shed new light on the following fundamental research questions: Are sub-Milankovitch frequencies present in the late Pliocene with frequencies similar to those observed in the late Pleistocene and, if so, is the climate mechanism comparable (Chapter

  12. Late Pliocene millennial to Milankovitch-scale climate variability: A case study of Marine Isotope Stages 101-95 in the Mediterranean and adjacent North Atlantic

    NARCIS (Netherlands)

    Becker, Julia

    2005-01-01

    The selected time interval and sections should shed new light on the following fundamental research questions: Are sub-Milankovitch frequencies present in the late Pliocene with frequencies similar to those observed in the late Pleistocene and, if so, is the climate mechanism comparable (Chapter

  13. Late Pliocene millennial to Milankovitch-scale climate variability : A case study of marine isotope stages 101-95 in the Mediterranean and adjacent North Atlantic

    NARCIS (Netherlands)

    Becker, J.

    2005-01-01

    The selected time interval and sections should shed new light on the following fundamental research questions: Are sub-Milankovitch frequencies present in the late Pliocene with frequencies similar to those observed in the late Pleistocene and, if so, is the climate mechanism comparable (Chapter 2)?

  14. Limit Cycles and Analytic Centers for a Family of 4n-1 Degree Systems with Generalized Nilpotent Singularities

    Directory of Open Access Journals (Sweden)

    Yusen Wu

    2015-01-01

    Full Text Available With the aid of computer algebra system Mathematica 8.0 and by the integral factor method, for a family of generalized nilpotent systems, we first compute the first several quasi-Lyapunov constants, by vanishing them and rigorous proof, and then we get sufficient and necessary conditions under which the systems admit analytic centers at the origin. In addition, we present that seven amplitude limit cycles can be created from the origin. As an example, we give a concrete system with seven limit cycles via parameter perturbations to illustrate our conclusion. An interesting phenomenon is that the exponent parameter n controls the singular point type of the studied system. The main results generalize and improve the previously known results in Pan.

  15. Linear and non-linear response of late Neogene glacial cycles to obliquity forcing and implications for the Milankovitch theory

    NARCIS (Netherlands)

    Lourens, L.J.; Becker, J.; Bintanja, R.; Hilgen, F.J.; Tuenter, E.; Wal, R.S.W. van de; Ziegler, M.

    2010-01-01

    Constraints are given for the geometry and time lags of the prominent obliquity-paced glacial stages 100, 98 and 96, which mark a major phase in Northern Hemisphere (NH) glaciations during the late Pliocene (2.56–2.4 Ma ago). For this purpose a high-resolution benthic δ18O record was constructed fro

  16. Comprehensive Technical Report, General Electric Direct-Air-Cycle Aircraft Nuclear Propulsion Program, Program Summary and References

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, G.; Rothstein, A.J.

    1962-06-28

    This is one of twenty-one volumes sumarizing the Aircraft Nuclear Propulsion Program of the General Electric Company. This volume discusses the background to the General Electric program, and summarizes the various direct-air-cycle nuclear test assemblies and power plants that were developed. Because of the requirements of high performance, low weight, and small size, vast improvements in existing technology were required to meet the flight objectives. The technological progress achieved during the program is also summarized. The last appendix contains a compilation of the abstracts, tables of contents, and reference lists of the other twenty volumes.

  17. Leg general muscle moment and power patterns in able-bodied subjects during recumbent cycle ergometry with ankle immobilization.

    Science.gov (United States)

    Szecsi, J; Straube, A; Fornusek, C

    2014-11-01

    Rehabilitation of persons with pareses commonly uses recumbent pedalling and a rigid pedal boot that fixes the ankle joint from moving. This study was performed to provide general muscle moments (GMM) and joint power data from able-bodied subjects performing recumbent cycling at two workloads. Twenty-six able-bodied subjects pedalled a stationary recumbent tricycle at 60 rpm during passive cycling and at two workloads (low 15 W and high 40 W per leg) while leg kinematics and pedal forces were recorded. GMM and power were calculated using inverse dynamic equations. During the high workload, the hip and knee muscles produced extensor/flexor moments throughout the extensions/flexions phases of the joints. For low workload, a prolonged (crank angle 0-258°) hip extension moment and a shortened range (350-150°) of knee extension moment were observed compared to the corresponding extension phases of each joint. The knee and hip joints generated approximately equal power. At the high workload the hip and knee extensors generated increased power in the propulsion phase. For the first time, this study provides GMM and power patterns for able-bodied subjects performing recumbent cycling with an immobilized ankle. The patterns showed greater similarities to upright cycling with a free ankle, than previously supposed.

  18. Towards a better representation of the solar cycle in general circulation models

    Directory of Open Access Journals (Sweden)

    K. M. Nissen

    2007-10-01

    Full Text Available We introduce the improved Freie Universität Berlin (FUB high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB. Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction of the solar SW heating rate signal by about 20%.

    The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal.

    Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60–70 km indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account.

    The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy.

  19. Towards a better representation of the solar cycle in general circulation models

    Science.gov (United States)

    Nissen, K. M.; Matthes, K.; Langematz, U.; Mayer, B.

    2007-10-01

    We introduce the improved Freie Universität Berlin (FUB) high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction) of the solar SW heating rate signal by about 20%. The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal. Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60-70 km) indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

  20. The Housing Careers of Older Canadians: An Investigation Using Cycle 16 of the General Social Survey

    Directory of Open Access Journals (Sweden)

    Michael Haan

    2008-12-01

    Full Text Available In this paper we use the Aging and Social Support Survey (GSS16 and the theoretical conception of a ‘housing career’ to identify the correlates of housing tenure (rent vs. own among Canadians age 45 and over. We draw on primarily US literature to isolate three general explanatory clusters (social support, health, and economic characteristics. Based on analyses using logistic regression, the results indicate that the majority of variation in housing tenure exists due to standard demographic and household characteristics. In fact, of the three focal explanatory clusters, only social support characteristics significantly enhance model fit beyond the baseline model, suggesting that the housing tenure of older Canadians hinges heavily on fairly standard characteristics.

  1. Modeling Two-Phase Flow and Vapor Cycles Using the Generalized Fluid System Simulation Program

    Science.gov (United States)

    Smith, Amanda D.; Majumdar, Alok K.

    2017-01-01

    This work presents three new applications for the general purpose fluid network solver code GFSSP developed at NASA's Marshall Space Flight Center: (1) cooling tower, (2) vapor-compression refrigeration system, and (3) vapor-expansion power generation system. These systems are widely used across engineering disciplines in a variety of energy systems, and these models expand the capabilities and the use of GFSSP to include fluids and features that are not part of its present set of provided examples. GFSSP provides pressure, temperature, and species concentrations at designated locations, or nodes, within a fluid network based on a finite volume formulation of thermodynamics and conservation laws. This paper describes the theoretical basis for the construction of the models, their implementation in the current GFSSP modeling system, and a brief evaluation of the usefulness of the model results, as well as their applicability toward a broader spectrum of analytical problems in both university teaching and engineering research.

  2. Late Pliocene millennial to Milankovitch-scale climate variability: A case study of Marine Isotope Stages 101-95 in the Mediterranean and adjacent North Atlantic

    OpenAIRE

    Becker, Julia

    2005-01-01

    The selected time interval and sections should shed new light on the following fundamental research questions: Are sub-Milankovitch frequencies present in the late Pliocene with frequencies similar to those observed in the late Pleistocene and, if so, is the climate mechanism comparable (Chapter 2)? What is the relationship of these signals with high latitude and low latitude climate (Chapter 3 and 4)? Are the phase relations of the different climate components with respect to the primary for...

  3. The annual pressure cycle on Mars: Results from the LMD Martian atmospheric general circulation model

    Science.gov (United States)

    Hourdin, Frederic; Forget, Francois; Talagrand, O.

    1993-01-01

    We have been developing a General Circulation Model (GCM) of the martian atmosphere since 1989. The model has been described rather extensively elsewhere and only the main characteristics are given here. The dynamical part of the model, adapted from the LMD terrestrial climate model, is based on a finite-difference formulation of the classical 'primitive equations of meteorology.' The radiative transfer code includes absorption and emission by CO2 (carefully validated by comparison to line-by-line calculations) and dust in the thermal range and absorption and scattering by dust in the visible range. Other physical parameterizations are included: modeling of vertical turbulent mixing, dry convective adjustment (in order to prevent vertical unstable temperature profiles), and a multilayer model of the thermal conduction in the soil. Finally, the condensation-sublimation of CO2 is introduced through specification of a pressure-dependent condensation temperature. The atmospheric and surface temperatures are prevented from falling below this critical temperature by condensation and direct precipitation onto the surface of atmospheric CO2. The only prespecified spatial fields are the surface thermal inertia, albedo, and topography.

  4. Entropy production and efficiency analysis of the Bunsen reaction in the General Atomic sulfur-iodine thermochemical hydrogen production cycle

    Energy Technology Data Exchange (ETDEWEB)

    Davis, M.E.; Conger, W.L.

    1980-01-01

    An entropy production and efficiency analysis of the first reaction in the General Atomic sulfur-iodine thermochemical hydrogen production cycle has been carried out by simulating the reaction including the mixing of reactants and separation of the resulting phases. The reaction: 2H/sub 2/O(L) + SO/sub 2/(g) + (excess) I/sub 2/(g) = H/sub 2/SO/sub 4/ (sol)(Phase I) + 2 HI core (Phase II) was simulated at 388 K, which is slightly above the melting point of I/sup 2/. Analysis of only this reaction shows that the reaction should be run at 15 to 25% I/sub 2/ reacted and the greatest excess of H/sub 2/O which will produce two product phases. Actual operating conditions are however dependent on the total processing scheme. An entropy production and efficiency analysis along with economic factors for the entire process is necessary to obtain these conditions.

  5. Overview of the SOFIA Data Cycle System: An integrated set of tools and services for the SOFIA General Investigator

    CERN Document Server

    Shuping, R Y; Lin, Lan; Sun, Li; Krzaczek, Robert

    2013-01-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne astronomical observatory comprised of a 2.5 meter infrared telescope mounted in the aft section of a Boeing 747SP aircraft that flies at operational altitudes between 37,000 and 45,00 feet, above 99% of atmospheric water vapor. During routine operations, a host of instruments will be available to the astronomical community including cameras and spectrographs in the near- to far-IR; a sub-mm heterodyne receiver; and an high-speed occultation imager. One of the challenges for SOFIA (and all observatories in general) is providing a uniform set of tools that enable the non-expert General Investigator (GI) to propose, plan, and obtain observations using a variety of very different instruments in an easy and seamless manner. The SOFIA Data Cycle System (DCS) is an integrated set of services and user tools for the SOFIA Science and Mission Operations GI Program designed to address this challenge. Program activities supported by the DCS inclu...

  6. Studies on generalized kinetic model and Pareto optimization of a product-driven self-cycling bioprocess.

    Science.gov (United States)

    Sun, Kaibiao; Kasperski, Andrzej; Tian, Yuan

    2014-10-01

    The aim of this study is the optimization of a product-driven self-cycling bioprocess and presentation of a way to determine the best possible decision variables out of a set of alternatives based on the designed model. Initially, a product-driven generalized kinetic model, which allows a flexible choice of the most appropriate kinetics is designed and analysed. The optimization problem is given as the bi-objective one, where maximization of biomass productivity and minimization of unproductive loss of substrate are the objective functions. Then, the Pareto fronts are calculated for exemplary kinetics. It is found that in the designed bioprocess, a decrease of emptying/refilling fraction and an increase of substrate feeding concentration cause an increase of the biomass productivity. An increase of emptying/refilling fraction and a decrease of substrate feeding concentration cause a decrease of unproductive loss of substrate. The preferred solutions are calculated using the minimum distance from an ideal solution method, while giving proposals of their modifications derived from a decision maker's reactions to the generated solutions.

  7. Research on the general analytical method of fossil fuel cycle from a viewpoint of the global environment. 3; Chikyu kankyo kara mita sogoteki kaseki nenryo cycle bunseki hyoka shuho no chosa. 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    The general analysis/assessment method of a fossil fuel cycle was studied. Seven kinds of power generation plants such as LNG cycle and coal cycle ones, and four kinds of transport and treatment systems of recovered CO2 such as ocean and underground systems were studied as case studies on life cycle analysis. As data necessary for life cycle analysis, the database was constructed which stores the facilities and operational energy required for a total energy system from mining of fossil fuel to treatment of recovered CO2, and the quantity of environmental waste such as CO2 emission. As a result, the decrease rate of energy balance defined as ratio of input energy to power plant output was estimated to be 14-43% and 20-60% in LNG cycle and coal cycle, respectively. Even if the recovery rate of CO2 in power plants reached 80-90%, reduction of total CO2 emission was limited to only 20-40% because of CO2 emission during mining, liquefaction and transport of fuel. 168 refs., 48 figs., 102 tabs.

  8. Cumulated insolation: a simple explanation of Milankovitch's forcing on climate changes

    Directory of Open Access Journals (Sweden)

    F. Marra

    2013-10-01

    Full Text Available The occurrence of the sudden melting of the ice sheets during the glacial terminations is explained in this paper as the consequence of the combined role of the minima and the maxima of mean summer insolation on the Northern Hemisphere, providing a new contribution to understand the mechanisms ruling glacial forcing. Indeed, no satisfactory answer has been provided so far to the question why one specific maximum, after a series of consecutive maxima of insolation, has the potentiality to trigger a deglaciation. The explanation proposed in this paper accounts for a pre-conditioning factor, represented by "mild" (warmer minimum, followed by a sufficiently warm maximum as the conditions that cause the end of a glacial cycle. These conditions are realized whenever the sum of the values of each consecutive minima and maxima ("cumulated insolation" on the curve of mean summer insolation at 65° N exceeds 742 Watt m−2. The comparison of the succession of these cumulated insolation values with the astronomically tuned Oxygen isotopes record provides a satisfactory match with the occurrence of all the glacial terminations in the last 800 ka.

  9. Milankovitch hypothesis supported by precise dating of coral reefs and deep-sea sediments.

    Science.gov (United States)

    Broecker, W S; Thurber, D L; Goddard, J; Ku, T L; Matthews, R K; Mesolella, K J

    1968-01-19

    Barbados provides a possibly unique opportunity for reconstruction of the times and elevations of late-Pleistocene high stands of the sea. The island appears to be rising from the sea at a uniform rate that is fast enough to separate in elevation coral-reef tracts formed at successive high stands of the sea. Unaltered coral found in the lower terraces enables high-precision Th(230): U(234) and Pa(231): U(235) dating. Three distinct high stands of the sea are found about 122,000, 103,000, and 82,000 years ago. New Pa(231) and Th(230) dates from a deep-sea core also indicate that Ericson's W-X cold-to-warm climatic change occurred close to 126,000 years ago. These data show a parallelism over the last 150,000 years between changes in Earth's climate and changes in the summer insolation predicted from cycles in the tilt and precession of Earth's axis.

  10. Tropical Ice Core Records: Evidence for Asynchronous Glaciation on Milankovitch Time Scales

    Science.gov (United States)

    Thompson, L. G.

    2001-12-01

    Puruogangri (34° N) suggest that the ice present today in the Himalayas and central Tibet formed during the time of greatest summer monsoon activity less than 10 kyr B.P. The younger basal ages for the Dasuopu and Puruogangri cores, coupled with the basal ages in the Andean ice caps, suggests an interesting scenario for the formation of permanent ice fields on these high elevation, low latitude mountains. Moving from 18° S to 9° S to 28° - 34° N, the ice fields appear to have successively younger basal ages (e.g., 25, 19 and ~8 kyr B.P.). Specifically, it is proposed that a northward migration of `the age of glacier formation' occurred as the axis of Intertropical Convergence Zone (ITCZ), the major moisture supply, moved northward. At present, the average latitude of the ITCZ is ~5° N. This narrow band of intense upward water vapor flux determines the position of wet/dry climatic zones over a large portion of the tropics; therefore, any long-term change in its mean position could lead to asynchronous glacier formation/starvation. In fact, the precession cycle reached its Southern Hemisphere maximum about 23 kyr B.P. and its Northern Hemisphere maximum about 11 kyr. This is remarkably consistent with the latitudinal pattern of glacier formation proposed here. This precessional migration provides a powerful working hypothesis for investigating tropical climate records. The nature of this relationship has major implications for understanding the processes controlling global climate.

  11. Damping of glacial-interglacial cycles from anthropogenic forcing

    CERN Document Server

    Haqq-Misra, Jacob

    2014-01-01

    Climate variability over the past million years shows a strong glacial-interglacial cycle of ~100,000 years as a combined result of Milankovitch orbital forcing and climatic resonance. It has been suggested that anthropogenic contributions to radiative forcing may extend the length of the present interglacial, but the effects of anthropogenic forcing on the periodicity of glacial-interglacial cycles has received little attention. Here I demonstrate that moderate anthropogenic forcing can act to damp this 100,000 year cycle and reduce climate variability from orbital forcing. Future changes in solar insolation alone will continue to drive a 100,000 year climate cycle over the next million years, but the presence of anthropogenic warming can force the climate into an ice-free state that only weakly responds to orbital forcing. Sufficiently strong anthropogenic forcing that eliminates the glacial-interglacial cycle may serve as an indication of an epoch transition from the Pleistocene to the Anthropocene.

  12. The role of motivation of students career in surgery in the cycle «general surgery»

    Directory of Open Access Journals (Sweden)

    А. V. Kapshytar

    2013-06-01

    Full Text Available At all times, a high degree of motivation for the choice of the medical profession, was a determining factor for the income and education in medical school of III-IV accreditation levels [1, 2, 5, 6, 9]. Many young people even at the pre-university stage, decided to dedicate their lives surgery [3, 4, 8, 9]. Getting practice in the surgical clinic at the famous and well-known professors is additional motivation for the students to choose surgeon path [2 - 4, 10]. Purpose: to study the motives for surgeon career choices by III year students in the cycle «General Surgery». Material and methods. The important role of the teacher in the department of General surgery and patient care ZSMU to awake and motivate student to master theoretical knowledge and practical skills in the surgery. Students who passed the theoretical departments have onlytheoretical knowledge of the basic pathological processes and they don’t have experience in working with patients. Many of them are insecure due to the necessity of mastering the wealth of knowledge and responsibility for making decision. Its dramatically reduces the desire to study. In this situation, teacher should identify motivation for the acquisition of basic knowledge in surgery on the practical sessions and lectures. Results and its discussion. To solve this problem in the surgical department of Community Hospital ‘City Clinical Hospital № 2’ in Zaporozhye survey questionnaires and it’s analysis have been taken place. It was found that over the past year, a desire to become surgeons was expressed in 26,2% of the students. The key motives for pre-selection of this profession were: presence of family medical dynasties (48,6%, positive experience of treatment by a surgeon in the past (21,1%, positive health education (12,5%. Therefore, most of the students' motivation was found before entering the ZSMU. At the end of the course ‘general surgery’ none of the students has changed his/her dream

  13. Life cycle costing for current Rohr and AM general buses and General Motors RTS-II bus. Final report, Mar 1976--Jul 1976

    Energy Technology Data Exchange (ETDEWEB)

    Kain, H.R.; Marks, G.J.; Staszak, L.A.

    1976-07-09

    UMTA is considering the use of the life cycle costing concept in the procurement procedures for intracity buses. These relevant factors have been identified as the bus price, maintenance costs (including preventive maintenance), fuel costs, and tire costs. Evaluation of practices of bus operators and manufacturers indicates that they are in a position to agree mutually upon an evaluation process dependent upon: (1) maintenance cost data, (2) design-related maintenance elements, (3) fuel and tire costs, (4) useful life of a bus for evaluation purposes, and (5) initial bus purchase price. Inasmuch as the follow-on costs considered in the evaluation of bus bids exceed the cost of the bus itself, the life cycle costing approach highlights the follow-on costs. Of paramount importance is the flexibility to introduce design improvements that can result in savings during the life of the bus.

  14. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 1: Open-cycle gas turbines

    Science.gov (United States)

    Brown, D. H.; Corman, J. C.

    1976-01-01

    Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle; open-cycle MHD; closed-cycle inert gas MHD; closed-cycle liquid metal MHD; and fuel cells. Results are presented.

  15. The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

    Science.gov (United States)

    Kahre, Melinda A.; Hollingsworth, Jeffery

    2012-01-01

    The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

  16. Orbit-related long-term climate cycles revealed in a 12-Myr continental record from Lake Baikal.

    Science.gov (United States)

    Kashiwaya, K; Ochiai, S; Sakai, H; Kawai, T

    2001-03-01

    Quaternary records of climate change from terrestrial sources, such as lake sediments and aeolian sediments, in general agree well with marine records. But continuous records that cover more than the past one million years were essentially unavailable until recently, when the high-sedimentation-rate site of Lake Baikal was exploited. Because of its location in the middle latitudes, Lake Baikal is highly sensitive to insolation changes and the entire lake remained uncovered by ice sheets throughout the Pleistocene epoch, making it a valuable archive for past climate. Here we examine long sediment cores from Lake Baikal that cover the past 12 million years. Our record reveals a gradual cooling of the Asian continental interior, with some fluctuations. Spectral analyses reveal periods of about 400 kyr, 600 kyr and 1,000 kyr, which may correspond to Milankovitch periods (reflecting orbital cycles). Our results indicate that changes in insolation were closely related to long-term environmental variations in the deep continental interior, over the past 12 million years.

  17. REACTOR AND SHIELD PHYSICS. Comprehensive Technical Report, General Electric Direct-Air-Cycle, Aircraft Nuclear Propulsion Program.

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, W.E.; Simpson, J.D.

    1962-01-01

    This volume is one of twenty-one summarizing the Aircraft Nuclear Propulsion Program of the General Electric Company. This volume describes the experimental and theoretical work accomplished in the areas of reactor and shield physics.

  18. A general G1/S-phase cell-cycle control module in the flowering plant Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Xin'Ai Zhao

    Full Text Available The decision to replicate its DNA is of crucial importance for every cell and, in many organisms, is decisive for the progression through the entire cell cycle. A comparison of animals versus yeast has shown that, although most of the involved cell-cycle regulators are divergent in both clades, they fulfill a similar role and the overall network topology of G1/S regulation is highly conserved. Using germline development as a model system, we identified a regulatory cascade controlling entry into S phase in the flowering plant Arabidopsis thaliana, which, as a member of the Plantae supergroup, is phylogenetically only distantly related to Opisthokonts such as yeast and animals. This module comprises the Arabidopsis homologs of the animal transcription factor E2F, the plant homolog of the animal transcriptional repressor Retinoblastoma (Rb-related 1 (RBR1, the plant-specific F-box protein F-BOX-LIKE 17 (FBL17, the plant specific cyclin-dependent kinase (CDK inhibitors KRPs, as well as CDKA;1, the plant homolog of the yeast and animal Cdc2⁺/Cdk1 kinases. Our data show that the principle of a double negative wiring of Rb proteins is highly conserved, likely representing a universal mechanism in eukaryotic cell-cycle control. However, this negative feedback of Rb proteins is differently implemented in plants as it is brought about through a quadruple negative regulation centered around the F-box protein FBL17 that mediates the degradation of CDK inhibitors but is itself directly repressed by Rb. Biomathematical simulations and subsequent experimental confirmation of computational predictions revealed that this regulatory circuit can give rise to hysteresis highlighting the here identified dosage sensitivity of CDK inhibitors in this network.

  19. How much deviations in sampling sedimentary series do impact on the reconstruction of climatic cycles?

    Science.gov (United States)

    Martinez, Mathieu; Kotov, Sergey; De Vleeschouwer, David; Pas, Damien; Pälike, Heiko

    2016-04-01

    Spectral analyses have become a key tool for detecting climatic cycles (like orbital forcing) in sedimentary series. Most of spectral analyses (like Fourier Transforms and derivative, MTM…) require a constant sample step. However, this is rarely achieved when collecting rock samples in outcrops or cores. Uncertainties in the sample positions distort the sedimentary series, which reduces the power spectrum of the short periods, like precession cycles. Here, we provide a tool for assessing how much a distortion in the sampling pattern impacts on the spectral power of a sedimentary series, with special focus on the Milankovitch band. We then assess how precise should be the control of a sample position as well as the required density of samples per precession cycle for reliably assess the spectral power in the whole Milankovitch band. Sample distances are randomised using gamma models to simulate distortions of the sedimentary series. Such approach allows the stratigraphic order of samples to be maintained as well as to parameterise the mean and the variance of the dispersion of the sample distances. We tested this sample distance randomisation on two published geological datasets that have been sampled at different steps. The spectra of the non-distorted and distorted series were calculated using the Lomb-Scargle and the Multi-Taper Method. When randomising sample diatances with an uncertainty of 5% of the mean sample step, all frequencies above ~1/3 of the Nyquist frequency are significantly reduced. At 10% and 15% uncertainty, all frequencies above respectively ~1/5 and ~1/6 of the Nyquist frequency are affected. This test illustrates that a precise stratigraphic control on the sample position as well as collecting at least 6-10 samples per precession cycle are required to reliably estimate the power spectrum in the whole Milankovitch band.

  20. Comprehensive Technical Report, General Electric Direct-Air-Cycle Aircraft Nuclear Propulsion Program; Aircraft Nuclear Propulsion Application Studies

    Energy Technology Data Exchange (ETDEWEB)

    Comassar, S.

    1962-04-30

    This volume is one of twenty-one summarizing the Aircraft Nuclear Propulsion Program of the General Electric Company. This portion describes the studies of advanced applications of nuclear reactors that were performed, including various types of aircraft, missiles, space vehicles, ships, and portable power plants.

  1. Comprehensive Technical Report, General Electric Direct-Air-Cycle Aircraft Nuclear Propulsion Program; Aircraft Nuclear Propulsion Application Studies

    Energy Technology Data Exchange (ETDEWEB)

    Comassar, S.

    1962-04-30

    This volume is one of twenty-one summarizing the Aircraft Nuclear Propulsion Program of the General Electric Company. This portion describes the studies of advanced applications of nuclear reactors that were performed, including various types of aircraft, missiles, space vehicles, ships, and portable power plants.

  2. 高分辨率地层学与Milankovitch旋回和ENSO事件沉积%HIGH RESOLUTION STRATIGRAPHY,MILANKOVITCH CYCLE AND ENSO EVENT DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    龚一鸣; 李保华

    1999-01-01

    围绕地质时间坐标的建立和优化,地层学经历了三次重要革命,形成了三种有代表性的地层学形态:斯坦诺地层学(1669年)、史密斯地层学(1817年)和高分辨率地层学(1969年).高分辨率地层学的显著特色是划分、对比出的主体地层单元的持续时间必须小于百万年级.十万年级至千年级高分辨率地层划分对比和高分辨率地质时间坐标的建立可望通过对地层记录中Milankovitch旋回和ENSO事件沉积的高分辨率地层学研究实现.

  3. A ~400 ka supra-Milankovitch cycle in the Na, Mg, Pb, Ni, and Co records of a ferromanganese crust from the Vityaz fracture zone, central Indian ridge.

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Gupta, S.M.; Miura, H.; Borole, D.V.

    at the geological ages, we used both sup(230)Th sub(execcs) and Co-chronometric datings. The correlation coefficient between the sup(230)Th sub(execcs) based dates and Co-chronometric dates for the top 0-8mm is very high (r=0.9734, at 99.9 percent significance...

  4. Experimental Study of Ambient Air Temperature Effects on The Performance of a General Vapor-Compression Refrigeration Cycle

    Directory of Open Access Journals (Sweden)

    Ayad T. Mustafa

    2013-05-01

    Full Text Available         In this work an experimental study for the vapor – compression refrigeration cycle has been performed under temperature range of  9.7-32°C. The effect of      varying temperature on heat exchangers pressures, cooling capacity, net power consumption, and coefficient of performance COP are studied .                                   The results indicated that condenser pressure, evaporator pressure, and power consumption increased with the increase of temperature. The data also indicated that cooling capacity increased as temperature increased until 15.6°C then after it decreased with further temperature increase. Also COP follow the same tread of cooling capacity.                                                                                                              

  5. Glacial cycles drive variations in the production of oceanic crust.

    Science.gov (United States)

    Crowley, John W; Katz, Richard F; Huybers, Peter; Langmuir, Charles H; Park, Sung-Hyun

    2015-03-13

    Glacial cycles redistribute water between oceans and continents, causing pressure changes in the upper mantle, with consequences for the melting of Earth's interior. Using Plio-Pleistocene sea-level variations as a forcing function, theoretical models of mid-ocean ridge dynamics that include melt transport predict temporal variations in crustal thickness of hundreds of meters. New bathymetry from the Australian-Antarctic ridge shows statistically significant spectral energy near the Milankovitch periods of 23, 41, and 100 thousand years, which is consistent with model predictions. These results suggest that abyssal hills, one of the most common bathymetric features on Earth, record the magmatic response to changes in sea level. The models and data support a link between glacial cycles at the surface and mantle melting at depth, recorded in the bathymetric fabric of the sea floor.

  6. 广义导热规律下广义卡诺循环的最优性能%The optimal performance of a generalized Carnot cycle for a generalized heat transfer law

    Institute of Scientific and Technical Information of China (English)

    朱小芹; 陈林根; 孙丰瑞

    2003-01-01

    The finite time thermodynamic performance of a generalized Carnot cycle, in which the heat transfer between the working fluid and the heat reservoirs obeys the generalized law Q∝(ΔT)m, is studied. The optimal configuration and the fundamental optimal relation between power and efficiency of the cycle are derived. Some special examples are discussed. The results can provide some theoretical guidance for the design a practical engine.%研究了有限热源条件下工质与热源间传热规律服从Q∝(ΔT)m时广义卡诺热机的有限时间热力学性能,导出了循环的最优构形及最优功率与效率间的基本优化关系,给出了某些特例分析,所得结果对实际热机的设计工作具有一定的理论指导作用.

  7. Discussion on climate oscillations: CMIP5 general circulation models versus a semi empirical harmonic model based on astronomical cycles

    CERN Document Server

    Scafetta, Nicola

    2013-01-01

    Power spectra of global surface temperature (GST) records reveal major periodicities at about 9.1, 10-11, 19-22 and 59-62 years. The Coupled Model Intercomparison Project 5 (CMIP5) general circulation models (GCMs), to be used in the IPCC (2013), are analyzed and found not able to reconstruct this variability. From 2000 to 2013.5 a GST plateau is observed while the GCMs predicted a warming rate of about 2 K/century. In contrast, the hypothesis that the climate is regulated by specific natural oscillations more accurately fits the GST records at multiple time scales. The climate sensitivity to CO2 doubling should be reduced by half, e.g. from the IPCC-2007 2.0-4.5 K range to 1.0-2.3 K with 1.5 C median. Also modern paleoclimatic temperature reconstructions yield the same conclusion. The observed natural oscillations could be driven by astronomical forcings. Herein I propose a semi empirical climate model made of six specific astronomical oscillations as constructors of the natural climate variability spanning ...

  8. Resistance for Genotoxic Damage in Mesenchymal Stromal Cells Is Increased by Hypoxia but Not Generally Dependent on p53-Regulated Cell Cycle Arrest

    Science.gov (United States)

    Wieduwild, Elisabeth; Nerger, Katrin; Lambrecht, Nina; Schmoll, Hans-Joachim; Müller-Tidow, Carsten; Müller, Lutz Peter

    2017-01-01

    Adult stem cells including multipotent mesenchymal stromal cells (MSC) acquire a high amount of DNA-damage due to their prolonged lifespan. MSC may exert specific mechanisms of resistance to avoid loss of functional activity. We have previously shown that resistance of MSC is associated with an induction of p53 and proliferation arrest upon genotoxic damage. Hypoxia may also contribute to resistance in MSC due to the low oxygen tension in the niche. In this study we characterized the role of p53 and contribution of hypoxia in resistance of MSC to genotoxic damage. MSC exhibited increased resistance to cisplatin induced DNA-damage. This resistance was associated with a temporary G2/M cell cycle arrest, induction of p53- and p21-expression and reduced cyclin B / cdk1-levels upon subapoptotic damage. Resistance of MSC to cisplatin was increased at hypoxic conditions i. e. oxygen <0.5%. However, upon hypoxia the cisplatin-induced cell cycle arrest and expression of p53 and p21 were abrogated. MSC with shRNA-mediated p53 knock-down showed a reduced cell cycle arrest and increased cyclin B / cdk1 expression. However, this functional p53 knock down did not alter the resistance to cisplatin. In contrast to cisplatin, functional p53-knock-down increased the resistance of MSC to etoposide. We conclude that resistance of MSC to genotoxic damage is influenced by oxygen tension but is not generally dependent on p53. Thus, p53-dependent and p53-independent mechanisms of resistance are likely to contribute to the life-long functional activity of MSC in vivo. These findings indicate that hypoxia and different resistance pathways contribute to the phenotype that enables the prolonged lifespan of MSC. PMID:28081228

  9. Koszul cycles

    CERN Document Server

    Bruns, Winfreid; Römer, Tim

    2010-01-01

    We prove regularity bounds for Koszul cycles holding for every ideal of dimension at most 1 in a polynomial ring. We generalize the lower bound for the Green-Lazarsfeld index of Veronese rings we proved in arXiv:0902.2431 to the multihomogeneous setting.

  10. Refining the Early Devonian time scale using Milankovitch cyclicity in Lochkovian-Pragian sediments (Prague Synform, Czech Republic)

    Science.gov (United States)

    Da Silva, A. C.; Hladil, J.; Chadimová, L.; Slavík, L.; Hilgen, F. J.; Bábek, O.; Dekkers, M. J.

    2016-12-01

    The Early Devonian geological time scale (base of the Devonian at 418.8 ± 2.9 Myr, Becker et al., 2012) suffers from poor age control, with associated large uncertainties between 2.5 and 4.2 Myr on the stage boundaries. Identifying orbital cycles from sedimentary successions can serve as a very powerful chronometer to test and, where appropriate, improve age models. Here, we focus on the Lochkovian and Pragian, the two lowermost Devonian stages. High-resolution magnetic susceptibility (χin - 5 to 10 cm sampling interval) and gamma ray spectrometry (GRS - 25 to 50 cm sampling interval) records were gathered from two main limestone sections, Požár-CS (118 m, spanning the Lochkov and Praha Formations) and Pod Barrandovem (174 m; Praha Formation), both in the Czech Republic. An additional section (Branžovy, 65 m, Praha Formation) was sampled for GRS (every 50 cm). The χin and GRS records are very similar, so χin variations are driven by variations in the samples' paramagnetic clay mineral content, reflecting changes in detrital input. Therefore, climatic variations are very likely captured in our records. Multiple spectral analysis and statistical techniques such as: Continuous Wavelet Transform, Evolutive Harmonic Analysis, Multi-taper method and Average Spectral Misfit, were used in concert to reach an optimal astronomical interpretation. The Požár-CS section shows distinctly varying sediment accumulation rates. The Lochkovian (essentially equivalent to the Lochkov Formation (Fm.)) is interpreted to include a total of nineteen 405 kyr eccentricity cycles, constraining its duration to 7.7 ± 2.8 Myr. The Praha Fm. includes fourteen 405 kyr eccentricity cycles in the three sampled sections, while the Pragian Stage only includes about four 405 kyr eccentricity cycles, thus exhibiting durations of 5.7 ± 0.6 Myr and 1.7 ± 0.7 Myr respectively. Because the Lochkov Fm. contains an interval with very low sediment accumulation rate and because the Praha Fm. was

  11. Green-house gas mitigation capacity of a small scale rural biogas plant calculations for Bangladesh through a general life cycle assessment.

    Science.gov (United States)

    Rahman, Khondokar M; Melville, Lynsey; Fulford, David; Huq, Sm Imamul

    2017-08-01

    Calculations towards determining the greenhouse gas mitigation capacity of a small-scale biogas plant (3.2 m(3) plant) using cow dung in Bangladesh are presented. A general life cycle assessment was used, evaluating key parameters (biogas, methane, construction materials and feedstock demands) to determine the net environmental impact. The global warming potential saving through the use of biogas as a cooking fuel is reduced from 0.40 kg CO2 equivalent to 0.064 kg CO2 equivalent per kilogram of dung. Biomethane used for cooking can contribute towards mitigation of global warming. Prior to utilisation of the global warming potential of methane (from 3.2 m(3) biogas plant), the global warming potential is 13 t of carbon dioxide equivalent. This reduced to 2 t as a result of complete combustion of methane. The global warming potential saving of a bioenergy plant across a 20-year life cycle is 217 t of carbon dioxide equivalent, which is 11 t per year. The global warming potential of the resultant digestate is zero and from construction materials is less than 1% of total global warming potential. When the biogas is used as a fuel for cooking, the global warming potential will reduce by 83% compare with the traditional wood biomass cooking system. The total 80 MJ of energy that can be produced from a 3.2 m(3) anaerobic digestion plant would replace 1.9 t of fuel wood or 632 kg of kerosene currently used annually in Bangladesh. The digestate can also be used as a nutrient rich fertiliser substituting more costly inorganic fertilisers, with no global warming potential impact.

  12. Lateral variations of carbonate platform facies and cycles: The Dachstein Limestone (Late Triassic, Northern Calcareous Alps, Austria)

    Science.gov (United States)

    Samankassou, Elias; Enos, Paul

    2017-04-01

    The driving mechanisms of cyclic patterns in shallow-water platform carbonates remain controversial. The focus of the present paper is to quantify lateral facies variations for a long stratigraphic record in an extensive, continuous, well-exposed cliff of the Dachstein platform that is composed, as many other Phanerozoic carbonate platforms, of peritidal deposits. We noted the lateral continuity of the beds to the degree permitted by the outcrop, generally a few tens or hundreds of meters; exceptionally up to 1.7 km. The study demonstrates the importance of quantification to evaluate origins of sedimentary cycles. The upper 885 m of the Triassic Dachstein platform limestone at Steinernes Meer, Saalfelden, Austria, includes 241 peritidal cycles overlain by 275 m of subtidal, non-cyclic and weakly cyclic limestone. Of 558 subtidal and intertidal beds measured, 121 (21.7%) disappear laterally. An additional 74 beds (13.3%) show significant (>10%) lateral variations in thickness. Mean thickness variation is 50%. Both lateral variations and discontinuities appear to lack a spatial vector. Disappearances toward the inferred platform interior (west), total 10.4% of the beds. East toward the inferred platform margin 11.3% of the beds disappear. Thickness changes occur in 6.6% of beds in each direction. The lack of lateral continuity of beds is consistent with a non-eustatic component to stratification. Erosion of intertidal intervals is the process that can be most readily documented. Erosion, transport, and non-uniform distribution of sediments, superposed on stratigraphic sequences driven by eustacy, are the likely processes which produced the complex, randomly recorded cycle patterns. Cycle duration may not be exclusively determined by Milankovitch processes, as suggested by the discrepancies in the cycle duration and interpretation among stratigraphers of the Dachstein, as well as other Phanerozoic carbonate platforms. Signals deduced from linearly measured sections

  13. Spectrum of 100-kyr glacial cycle: orbital inclination, not eccentricity.

    Science.gov (United States)

    Muller, R A; MacDonald, G J

    1997-08-05

    Spectral analysis of climate data shows a strong narrow peak with period approximately 100 kyr, attributed by the Milankovitch theory to changes in the eccentricity of the earth's orbit. The narrowness of the peak does suggest an astronomical origin; however the shape of the peak is incompatible with both linear and nonlinear models that attribute the cycle to eccentricity or (equivalently) to the envelope of the precession. In contrast, the orbital inclination parameter gives a good match to both the spectrum and bispectrum of the climate data. Extraterrestrial accretion from meteoroids or interplanetary dust is proposed as a mechanism that could link inclination to climate, and experimental tests are described that could prove or disprove this hypothesis.

  14. Acceleration technique for Milankovitch type forcing in a coupled atmosphere-ocean circulation model: method and application for the Holocene

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Stephan J. [Modelle und Daten, Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Lohmann, Gerrit [Universitaet Bremen, Fachbereich Geowissenschaften und DFG Forschungszentrum Ozeanraender, Postfach 330440, Bremen (Germany)

    2004-12-01

    A method is introduced which allows the calculation of long-term climate trends within the framework of a coupled atmosphere-ocean circulation model. The change in the seasonal cycle of incident solar radiation induced by varying orbital parameters has been accelerated by factors of 10 and 100 in order to allow transient simulations over the period from the mid-Holocene until today, covering the last 7,000 years. In contrast to conventional time-slice experiments, this approach is not restricted to equilibrium simulations and is capable to utilise all available data for validation. We find that opposing Holocene climate trends in tropics and extra-tropics are a robust feature in our experiments. Results from the transient simulations of the mid-Holocene climate at 6,000 years before present show considerable differences to atmosphere-alone model simulations, in particular at high latitudes, attributed to atmosphere-ocean-sea ice effects. The simulations were extended for the time period 1800-2000 AD, where, in contrast to the Holocene climate, increased concentrations of greenhouse gases in the atmosphere provide for the strongest driving mechanism. The experiments reveal that a Northern Hemisphere cooling trend over the Holocene is completely cancelled by the warming trend during the last century, which brings the recent global warming into a long-term context. (orig.)

  15. 鄂尔多斯盆地米兰科维奇旋回在延长组发育的一致性%Uniformity of the Milankovitch Cycle developed in the Yanchang Formation in east Gansu with the Milankovitch Cycle developed in other areas in Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    李凤杰; 郑荣才; 赵俊兴

    2008-01-01

    通过高分辨率基准面旋回和测井曲线的频谱分析研究,认为在鄂尔多斯盆地陇东地区延长组湖相碎屑岩地层中,沉积旋回的周期变化可以反映米兰科维奇旋回.该旋回与鄂尔多斯盆地靖安油田和陕北地区延长组中的米兰科维奇旋回相对比,存在着较好的一致性,表明同时期的米兰科维奇旋回沉积记录,可以在鄂尔多斯盆地相距很远的不同沉积区同时发育.由于受区域性乃至全球性气候的制约,该旋回同时发育于鄂尔多斯盆地延长组的不同沉积地点及不同沉积相区,从而进一步支持米兰科维奇理论.

  16. Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda

    Directory of Open Access Journals (Sweden)

    J. W. Fourqurean

    2015-07-01

    Full Text Available Striking spatial patterns in stable isotope ratios (isoscapes and elemental ratios (stoichioscapes of seagrass leaves and the water column nutrients indicate general P-limitation of both water column and benthic primary productivity on the Bermuda Platform, and they highlight the role of the Bermuda Islands as a source of N and P. We found consistent differences among the four seagrass species (Syringodium filiforme, Thalassia testudinum, Halodule sp. and Halophila decipiens in the N, P, δ13C and δ15N of leaf tissues. The δ15N of seagrass leaves was especially variable, with values from −10.1 to 8.8‰, greatly expanding the reported range of values for all seagrass species globally. Spatial patterns from both the water column and the seagrass leaves indicated that P availability was higher near shore, and δ15N values suggest this was likely a result of human waste disposal. Spatially-contiguous areas of extremely depleted seagrass δ15N suggest unique N sources and cycling compared to other seagrass-dominated environments. Seagrass N : P values were not as far from the stoichiometric balance between N and P availability as in the water column, and there were no strong relationships between the water column N : P and the seagrass N : P. Such isoscapes and stoichioscapes provide valuable ecogeochemical tools to infer ecosystem processes as well as provide information that can inform food web and animal movement studies.

  17. Glacial CO2 Cycles: A Composite Scenario

    Science.gov (United States)

    Broecker, W. S.

    2015-12-01

    There are three main contributors to the glacial drawdown of atmospheric CO2 content: starvation of the supply of carbon to the ocean-atmosphere reservoir, excess CO2 storage in the deep sea, and surface-ocean cooling. In this talk, I explore a scenario in which all three play significant roles. Key to this scenario is the assumption that deep ocean storage is related to the extent of nutrient stratification of the deep Atlantic. The stronger this stratification, the larger the storage of respiration CO2. Further, it is my contention that the link between Milankovitch insolation cycles and climate is reorganizations of the ocean's thermohaline circulation leading to changes in the deep ocean's CO2 storage. If this is the case, the deep Atlantic d13C record kept in benthic foraminifera shells tells us that deep ocean CO2 storage follows Northern Hemisphere summer insolation cycles and thus lacks the downward ramp so prominent in the records of sea level, benthic 18O and CO2. Rather, the ramp is created by the damping of planetary CO2 emissions during glacial time intervals. As it is premature to present a specific scenario, I provide an example as to how these three contributors might be combined. As their magnitudes and shapes remain largely unconstrained, the intent of this exercise is to provoke creative thinking.

  18. Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 1: Bottoming cycles and materials of construction

    Science.gov (United States)

    Shah, R. P.; Solomon, H. D.

    1976-01-01

    Energy conversion subsystems and components were evaluated in terms of advanced energy conversion systems. Results of the bottoming cycles and materials of construction studies are presented and discussed.

  19. Global environmental cycling of gamma-HCH and DDT in the 1980s--a study using a coupled atmosphere and ocean general circulation model.

    Science.gov (United States)

    Guglielmo, Francesca; Lammel, Gerhard; Maier-Reimer, Ernst

    2009-09-01

    A coupled atmosphere-ocean general circulation model, ECHAM5-MPIOM, was used to study the multicompartmental cycling and long-range transport of persistent and semivolatile organics. Multiphase systems in air and ocean are covered by submodels for atmospheric aerosols, HAM, and marine biogeochemistry, HAMOCC5, respectively. The model, furthermore, encompasses 2D surface compartments, i.e. top soil, vegetation surfaces and sea-ice. The total environmental fate of gamma-hexachlorocyclohexane (gamma-HCH, lindane) and dichlorophenyltrichloroethane (DDT) in agriculture were studied. DDT is mostly present in the soils, the water-soluble gamma-HCH in soils and ocean. DDT has the longest residence time in almost all compartments. Quasi-steady state with regard to substance accumulation is reached within a few years in air and vegetation surfaces. In seawater the partitioning to suspended and sinking particles contributes to the vertical transport of substances. On the global scale deep water formation is, however, found to be more efficient. Up to 30% of DDT but only less than 0.2% of gamma-HCH in seawater are stored in particulate matter. On the time scale studied (1 decade) and on global scale substance transport in the environment is determined by the fast atmospheric circulation. The meridional transport mechanism, for both compounds, is significantly enhanced by multi-hopping. Net meridional transport in the ocean is effective only regionally, mostly by currents along the western boundaries of Africa and the Americas. The total environmental burdens of the substances experience a net northward migration from their source regions, which is more pronounced for DDT than for gamma-HCH. Due to the application distribution, however, after 10 years of simulation 21% of the global environmental burden of gamma-HCH and 12% of DDT have accumulated in the Arctic.

  20. Conventional and intelligent generalized supervisory control for combined cycle generating power stations.; Control supervisiorio generalizado convencional e inteligente para centrales de generacion de ciclo combinado

    Energy Technology Data Exchange (ETDEWEB)

    Martinez M, Miguel A; Sanchez P, Marino [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Gonzalez Rubio S, Jose L [Cento Nacional de Investigacion y Desarrollo Tecnologico (Cenidet), Cuernavaca, Morelos (Mexico)

    2005-07-01

    Under the expectations of expansion of electric power generation in Mexico, this work exposes the development of a conventional and intelligent generalized supervisory control (CSG) for a combined cycle generation power plant. This one allows to obtain the optimal operation of the power plant through the automatic starting of the generating units and to obtain the maximum possible amount of electrical power in automatic and safe form. For the development of the CSG a control loop by temperature was implemented for the gas turbine system and a control loop by strangled pressure for the gas turbine and a control loop by strangled pressure for the steam turbine. The design of these supervisory systems was made with base in the critical limits on the involved variables of the process: blading average temperature, for the gas turbine (GT) and strangled pressure for the steam turbine (ST) [Spanish] Bajo estas expectativas de expansion de generacion de energia en Mexico, este trabajo expone el desarrollo de un control supervisorio generalizado (CSG) para una central generacion de ciclo combinado. Este permite lograr la operacion optima de la planta a traves del arranque automatico de las unidades generadoras y obtener la maxima cantidad posible de potencia electrica en forma automatica y segura. Para el desarrollo del CSG se implanto un lazo de control por temperatura para el sistema de turbina de gas y un lazo de control por presion estrangulada para la turbina de gas y un lazo de control por presion estrangulada para la turbina de vapor. El diseno de estos sistemas supervisorio se realizo con base en los limites criticos de las variables del proceso involucradas: temperatura promedio de empaletado para la turbina de gas (TG) y presion estrangulada para la turbina de vapor (TV)

  1. Northern Hemisphere forcing of climatic cycles in Antarctica over the past 360,000 years.

    Science.gov (United States)

    Kawamura, Kenji; Parrenin, Frédéric; Lisiecki, Lorraine; Uemura, Ryu; Vimeux, Françoise; Severinghaus, Jeffrey P; Hutterli, Manuel A; Nakazawa, Takakiyo; Aoki, Shuji; Jouzel, Jean; Raymo, Maureen E; Matsumoto, Koji; Nakata, Hisakazu; Motoyama, Hideaki; Fujita, Shuji; Goto-Azuma, Kumiko; Fujii, Yoshiyuki; Watanabe, Okitsugu

    2007-08-23

    The Milankovitch theory of climate change proposes that glacial-interglacial cycles are driven by changes in summer insolation at high northern latitudes. The timing of climate change in the Southern Hemisphere at glacial-interglacial transitions (which are known as terminations) relative to variations in summer insolation in the Northern Hemisphere is an important test of this hypothesis. So far, it has only been possible to apply this test to the most recent termination, because the dating uncertainty associated with older terminations is too large to allow phase relationships to be determined. Here we present a new chronology of Antarctic climate change over the past 360,000 years that is based on the ratio of oxygen to nitrogen molecules in air trapped in the Dome Fuji and Vostok ice cores. This ratio is a proxy for local summer insolation, and thus allows the chronology to be constructed by orbital tuning without the need to assume a lag between a climate record and an orbital parameter. The accuracy of the chronology allows us to examine the phase relationships between climate records from the ice cores and changes in insolation. Our results indicate that orbital-scale Antarctic climate change lags Northern Hemisphere insolation by a few millennia, and that the increases in Antarctic temperature and atmospheric carbon dioxide concentration during the last four terminations occurred within the rising phase of Northern Hemisphere summer insolation. These results support the Milankovitch theory that Northern Hemisphere summer insolation triggered the last four deglaciations.

  2. Application of Spectral Analysis to Identify Milankovitch Cyclesand High-Frequency Sequences- Take The Lower Ordovician Yingshan Formation of Mid-Tarim Basin as An Example%频谱分析法在识别米兰科维奇旋回及高频层序中的应用——以塔里木盆地塔中-巴楚地区下奥陶统鹰山组为例

    Institute of Scientific and Technical Information of China (English)

    张运波; 赵宗举; 袁圣强; 郑民

    2011-01-01

    在巴楚地区露头高频层序研究及塔中地区钻测井三级层序划分的基础上,对塔里木盆地塔中地区塔中162井和塔中43井下奥陶统鹰山组层序OSQ2的自然伽马能谱测井ln(Th/K)曲线进行了滤波处理、快速傅里叶变换处理、小波时频分析以及调谐处理,识别出具有米兰科维奇旋回特征的高频旋回.结果表明:斜度(黄赤交角)旋回最为明显,周期为37.0 ka.是以向上变浅为主的六级米级旋回的主要控制因素,其主旋回平均厚度在台地边缘相带的塔中162井及塔中43井中分别为4.55 m及3.97 m,在巴楚地区半局限-开阔台地相带中为2~4 m;95 ka的短偏心率周期是形成五级准层序的主要控制因素,而大致代表四级准层序组形成时限的413 ka长偏心率周期在地层记录中表现并不明显.据高频层序叠置关系分析及平均主旋回个数初步估算,塔中-巴楚地区下奥陶统鹰山组层序OSQ2的形成时限大约为4.92 Ma,塔中43井鹰山组层序OSQ2受后期构造隆升而被剥蚀约192 m.结合四级层序(准层序组)发育时限(413 ka)及其叠置关系,以及与其调谐的小波变换曲线特征,初步将塔中-巴楚地区鹰山组层序OSQ2划分出12个准层序组.自然伽马能谱测井ln(Th/K)曲线包含沉积古水深相对变化的信息,是反映气候变化生成的米兰科维奇旋回层序的良好指标.%Based on the division in 3th-sequence about loggings and drillings and the study on high-frequency sequence about the outcrops in Bachu area, the authors identifies the high-frequency sequences with the characteristics of Milankovitch cycle, via the filtering, fast Fourier transform, wavelet analysis and tuning processing of the natural gamma spectrometry log In(Th/K) curves of sequence OSQ2 of Lower ()rdovician Yingshan Formation in Tazhong162 and 43 drillings, Tazhong area, Tarim basin. The results show that the most obvious cycle is the obliquity, the period is 37.0 ka

  3. General description of capacity for sportswomen of high class in the period of ovarian-menstrual cycle at run on endurance

    Directory of Open Access Journals (Sweden)

    Klochko L.I.

    2012-01-01

    Full Text Available The level of separate components of physical capacity for sportswomen in the period of ovarian-menstrual cycle is examined. Directions of planning of training process of sportswomen are presented. The features of construction of trainings in at run on marathon distance are rotined. Factors which influence on the physical capacity of sportswomen are selected. The indexes of trained, which allow to decrease a traumatism for sportswomen, are set. Directions of change of dynamics of loadings taking into account the terms of leadthrough of forthcoming competitions and their accordance the phase of ovarian-menstrual cycle are offered.

  4. Best available practice in life cycle assessment of climate change, stratospheric ozone depletion, photo-oxidant formation, acidification, and eutrophication-Backgrounds on general issues

    NARCIS (Netherlands)

    Seppala J; Risbey J; Meilinger S; Norris G; Lindfors GL; Goedkoop M; Potting J; Klopffer W; SETAC Europe; KMD

    2001-01-01

    This report has been prepared by the SETAC Europe Scientific Task Group on Global And RegionaL Impact Categories (SETAC-Europe/STG-GARLIC) that is installed by the 2nd SETAC Europe working group on life cycle impact assessment (WIA-2). This document is background to a chapter written by the same aut

  5. Menstrual Cycle

    Science.gov (United States)

    ... Luteal (after egg release) Changes During the Menstrual Cycle The menstrual cycle is regulated by the complex interaction of ... egg release) Luteal (after egg release) The menstrual cycle begins with menstrual bleeding (menstruation), which marks the first day of ...

  6. Of horses and swords: The 25 May and the Wars of Independence in text books of the third cycle of basic general school of "educational transformation" of the 90s

    Directory of Open Access Journals (Sweden)

    Gonzalo Alvaro De Amézola

    2010-11-01

    Full Text Available This article analyzes the changes in the narrative of the independence of Argentina that the educative reform tried to introduce in textbooks for the third cycle of General Basic Education, the new compulsory education path defined by the reform of the 90s. These changes included an update of transmitting knowledge in school and the skills that history should be promoted in the classroom.

  7. Generalized conventional and intelligent supervisory control system for combined cycle generation power plants; Sistema de control supervisorio generalizado convencional e inteligente para centrales de generacion de ciclo combinado

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Morales, Miguel Angel

    2004-12-15

    The Mexican Electricity Utility (Comision Federal de Electricidad - CFE) growing program in Power Generation for the 2004 - 2008 period is based on Combined Cycle Power Plants (CCPP). In accordance with [CFE, 2000], the expected power generation capacity developed during such period will rise by the amount of 12876 MW, 10655 MW belonging to CCPP (82.75 %). With such important program for the increasing of Power Generation in Mexico, researches have to receive new technologies for CCPP, some of them not completely tested and immature, with the compromise to make then more efficient and reliable. Under such idea and looking to increase the automation level for CCPP with better control algorithms, the Supervisory Generalized Control (SGC) for CCPP was developed in this thesis, based on PID strategies and intelligent (fuzzy) control strategies. With the SGC is possible to get the best performance for the whole CCPP through the automatic starting, synchronizing and loading of the generating units (two gas turbines and one steam turbine) with a minimum participation of operators. To get the increased efficiency, the SGC generates the reference paths for both gas turbines (GT) first, and the steam turbine (ST). The SGC accelerates each unit with a minimum effort and vibrations getting the synchronizing speed in a minimum time and wasted energy. Then the SGC synchronize each unit taking minimum load quickly and loading up to the highest electric power value. All these can be done in an automated operation. The SGC employs two critical-process variable- control strategies, based on blade path temperature average (BPT Average) for Gas Turbines (GT) and the throttle steam pressure for the Steam Turbine (ST). The control algorithms designed take both units, the GT and the ST, picking up load to the highest process value avoiding the alarms activation and shutdown. This is possible only with such an automated control strategy. Test performed showed that with the SGC

  8. Biogeochemical Cycling

    Science.gov (United States)

    Bebout, Brad; Fonda, Mark (Technical Monitor)

    2002-01-01

    This lecture will introduce the concept of biogeochemical cycling. The roles of microbes in the cycling of nutrients, production and consumption of trace gases, and mineralization will be briefly introduced.

  9. Bifurcation of limit cycles near equivariant compound cycles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper we study some equivariant systems on the plane. We first give some criteria for the outer or inner stability of compound cycles of these systems. Then we investigate the number of limit cycles which appear near a compound cycle of a Hamiltonian equivariant system under equivariant perturbations. In the last part of the paper we present an application of our general theory to show that a Z3 equivariant system can have 13 limit cycles.

  10. Offshore Rankine Cycles

    OpenAIRE

    Brandsar, Jo

    2012-01-01

    The title of the thesis - "Offshore Rankine Cycles" - is very general and cover a large range of engineering fields, e.g. thermodynamic cycles (Rankine, ORC, Brayton, Kalina, etc.), mechanical equipment (gas/steam turbine, heat exchangers and additional equipment) and safety concerns (flammable and/or toxic fluids, high temperature and pressures), to name the most important.The thesis try to give a brief overview of all critical points and alternatives, concerning employment of a wa...

  11. Quasi-100 ky glacial-interglacial cycles triggered by subglacial burial carbon release

    Directory of Open Access Journals (Sweden)

    N. Zeng

    2006-07-01

    Full Text Available A new mechanism is proposed in which climate, carbon cycle and icesheets interact with each other to produce a feedback that can produce quasi-100 ky glacial-interglacial cycles. A key process is the burial and preservation of organic carbon by icesheets. The switch from glacial maximum to deglaciation is triggered by the ejection of glacial burial carbon when icesheets grow to sufficiently large size and subglacial transport becomes significant. Glacial inception is initiated by CO2 drawdown due to a ''rebound'' from a high but transient interglacial CO2 value as the land-originated CO2 invades into deep ocean via thermohaline circulation and CaCO3 compensation. Also important for glacial inception is the CO2 uptake by vegetation regrowth in the previously ice-covered boreal regions. When tested using a fully coupled Earth system model with comprehensive carbon cycle components and semi-empirical physical climate components, it produced self-sustaining glacial-interglacial cycles of duration about 93 ky, CO2 change of 90 ppmv, temperature change of 6°C under certain parameter regimes. Since the 100 ky cycles can not be easily explained by the weak Milankovitch astronomical forcing alone, this carbon-climate mechanism provides a strong feedback that could interact with external forcings to produce the major observed Quaternary climatic variations.

  12. FES cycling.

    Science.gov (United States)

    Newham, D J; Donaldson, N de N

    2007-01-01

    Spinal cord injury (SCI) leads to a partial or complete disruption of motor, sensory, and autonomic nerve pathways below the level of the lesion. In paraplegic patients, functional electrical stimulation (FES) was originally widely considered as a means to restore walking function but this was proved technically very difficult because of the numerous degrees of freedom involved in walking. FES cycling was developed for people with SCI and has the advantages that cycling can be maintained for reasonably long periods in trained muscles and the risk of falls is low. In the article, we review research findings relevant to the successful application of FES cycling including the effects on muscle size, strength and function, and the cardiovascular and bone changes. We also describe important practical considerations in FES cycling regarding the application of surface electrodes, training and setting up the stimulator limitations, implanted stimulators and FES cycling including FES cycling in groups and other FES exercises such as FES rowing.

  13. Recognition of sedimentary cycles of sandbodies in steep-slope zones of continental rifted basins —a case study of middle-shallow horizons in the northern Chexi Subsag of the Jiyang Depression%陆相断陷盆地陡坡带砂砾岩体期次划分——以济阳坳陷车西洼陷北带中浅层为例

    Institute of Scientific and Technical Information of China (English)

    宋亮; 苏朝光; 张营革; 郝志伟; 王楠

    2011-01-01

    In order to solve the problem of sedimentary cycle recognition of the middle-shallow sandbodies in the northern Chexi Subsag, we proposed a geologic- and seismic-constrained sedimentary cycle description method by using the Milankovitch cycle theory and wavelet transformation with well logging, constrained. Spectrum analysis of well logs shows that sedimentary cycle of sandbodies in Dongying Formation in the northern Chexi Subsag was controlled by the Milankovitch cycle. The fourth- and fifth-order sequences were controlled by the cycle of 404. 0 ka eccentricity and 53. 6 ka dip of earth' s axis, which is the foundation of the division and correlation of sandbody sedimentary cycle. According to the theories of Milankovitch cycle and wavelet transformation, we identified 8-10 small sedimentary fans vertically in the sandbodies of the Dongying Formation in the northern Chexi Subsag. The results show that analyses of high frequency cycles by using the Milankovitch cycle and wavelet transform can improve the quantificational level of sedimentary cycle division. The designed curves of Milankovitch cycle filters and the selected wavelet transformation coefficients correlate well with the high frequency cycles, and thus can be used to effectively recognize sedimentary cycles of sandbodies.%针对车西洼陷北带中浅层砂砾岩体期次划分困难的问题,初步探索出一种在地质和地震资料约束下,基于测井曲线米氏旋回和小波变换技术的砂砾岩体描述方法.通过对测井曲线进行频谱分析,认为车西洼陷北带东营组砂砾岩体的沉积期次受米氏旋回的控制,偏心率404.0 ka和地轴倾角53.6 ka周期控制着四、五级层序的发育,是进行砂砾岩体期次划分与对比的基础.因此,依据米氏旋回和小波变换理论,在纵向上对车西洼陷北带东营组砂砾岩体进行了精细的划分,共识别出8~10个小的扇体期次.研究表明,应用米氏旋回和小波变换技术分析高

  14. A general strategy to construct uniform carbon-coated spinel LiMn2O4 nanowires for ultrafast rechargeable lithium-ion batteries with a long cycle life

    Science.gov (United States)

    Sun, Weiwei; Liu, Huiqin; Liu, Yumin; Bai, Gongxun; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

    2015-07-01

    Control over one-dimensional growth of spinel-type LiMn2O4 nanowires is challenging in the area of materials science due to their cubic crystal structure. The current strategy is to use a self-support template to fabricate LiMn2O4 nanowires, which is time-consuming and limits their large-scale commercial production. In this paper, we propose a general strategy to construct well-defined LiMn2O4 nanowires terminated with amorphous carbon at the edges by an ingenious method without using any template. Benefited from its unique carbon-coated nanowire structure, the electrode exhibits a capacitor-like rate performance and battery-like high capacity for long-time cycling. Even after 1500 cycles at an extremely high current density of 30 C, approximately 82% of its initial capacity can still be retained. Significantly, the strategy reported here will be beneficial and revelatory to manufacture other extensive one-dimensional robust carbon-decorated nanowires, paving new ways for future developments of ultrafast rechargeable lithium-ion batteries.Control over one-dimensional growth of spinel-type LiMn2O4 nanowires is challenging in the area of materials science due to their cubic crystal structure. The current strategy is to use a self-support template to fabricate LiMn2O4 nanowires, which is time-consuming and limits their large-scale commercial production. In this paper, we propose a general strategy to construct well-defined LiMn2O4 nanowires terminated with amorphous carbon at the edges by an ingenious method without using any template. Benefited from its unique carbon-coated nanowire structure, the electrode exhibits a capacitor-like rate performance and battery-like high capacity for long-time cycling. Even after 1500 cycles at an extremely high current density of 30 C, approximately 82% of its initial capacity can still be retained. Significantly, the strategy reported here will be beneficial and revelatory to manufacture other extensive one-dimensional robust

  15. A new model for the global biogeochemical cycle of carbonyl sulfide - Part 1: Assessment of direct marine emissions with an oceanic general circulation and biogeochemistry model

    Science.gov (United States)

    Launois, T.; Belviso, S.; Bopp, L.; Fichot, C. G.; Peylin, P.

    2014-08-01

    The global budget of tropospheric carbonyl sulfide (OCS) is believed to be at equilibrium because background air concentrations have remained roughly stable over at least the last decade. Since the uptakes of OCS by leaves (associated to photosynthesis) and soils have been revised significantly upwards recently, an equilibrated budget can only be obtained with a compensatory source of OCS. It has been assumed that the missing source of OCS comes from the low latitude ocean, following the incident solar flux. The present work uses parameterizations of major production and removal processes of organic compounds in the NEMO-PISCES Ocean General Circulation and Biogeochemistry Model to assess the marine source of OCS. In addition, the OCS photo-production rates computed with the NEMO-PISCES model were evaluated independently using UV absorption coefficient of chromophoric dissolved organic matter (derived from satellite ocean color) and apparent quantum yields available in the literature. Our simulations show global direct marine emissions of COS in the range of 573-3997 Gg S yr-1, depending mostly on the quantification of the absorption rate of chromophoric dissolved organic matter. The high estimates on that range are unlikely, as they correspond to a formulation that most likely overestimate photo-production process. Low and medium (813 Gg S yr-1) estimates derived from the NEMO-PISCES model are however consistent spatially and temporally with the suggested missing source of Berry et al. (2013), allowing thus to close the global budget of OCS given the recent estimates of leaf and soil OCS uptakes.

  16. A new model for the global biogeochemical cycle of carbonyl sulfide – Part 1: Assessment of direct marine emissions with an oceanic general circulation and biogeochemistry model

    Directory of Open Access Journals (Sweden)

    T. Launois

    2014-08-01

    Full Text Available The global budget of tropospheric carbonyl sulfide (OCS is believed to be at equilibrium because background air concentrations have remained roughly stable over at least the last decade. Since the uptakes of OCS by leaves (associated to photosynthesis and soils have been revised significantly upwards recently, an equilibrated budget can only be obtained with a compensatory source of OCS. It has been assumed that the missing source of OCS comes from the low latitude ocean, following the incident solar flux. The present work uses parameterizations of major production and removal processes of organic compounds in the NEMO-PISCES Ocean General Circulation and Biogeochemistry Model to assess the marine source of OCS. In addition, the OCS photo-production rates computed with the NEMO-PISCES model were evaluated independently using UV absorption coefficient of chromophoric dissolved organic matter (derived from satellite ocean color and apparent quantum yields available in the literature. Our simulations show global direct marine emissions of COS in the range of 573–3997 Gg S yr−1, depending mostly on the quantification of the absorption rate of chromophoric dissolved organic matter. The high estimates on that range are unlikely, as they correspond to a formulation that most likely overestimate photo-production process. Low and medium (813 Gg S yr−1 estimates derived from the NEMO-PISCES model are however consistent spatially and temporally with the suggested missing source of Berry et al. (2013, allowing thus to close the global budget of OCS given the recent estimates of leaf and soil OCS uptakes.

  17. Earth's eccentricity cycles and Indian Summer Monsoon variability over the past 2 million years: Evidence from deep-sea benthic foraminifer

    Science.gov (United States)

    Gupta, Anil K.; Dhingra, Hitesh; Mélice, Jean-Luc; Anderson, David M.

    Spectral analysis of a Uvigerina proboscidea time series from DSDP Site 214 using the Lomb-Scargle method for unevenly sampled data, exhibits two dominant power peaks at 412 and 94 kyrs over the last 2 million years, which correspond to the Earth's eccentricity cycles. The results indicate that the SW monsoon varied at about 100 kyr and 400 kyr periodicities within Earth's eccentricity domain (Milankovitch range) over the past 2 million years. Wavelet transform analysis reveals the non-stationary nature of monsoon upwelling over this interval. The amplitude of the 400 kyr cycle in the U. proboscidea time series began to increase at ∼900 kyrs as has also been observed in few recent studies. We do not see a strong relation between eccentricity highs and intense summer monsoons over the studied interval.

  18. Correlation of basinal carbonate cycles to nearshore parasequences in the late Cretaceous Greenhorn seaway, Western Interior USA

    Science.gov (United States)

    Elder, W.P.; Gustason, E.R.; Sageman, B.B.

    1994-01-01

    In the central basin in Colorado and Kansas, these sedimentary cycles are represented by limestone-shale and marlstone-shale couplets ~0.5-1.0m in thickness. More calcareous parts of these couplets may be correlated westward into condensed, fossiliferous concretion and shell beds in proximal offshore lithofacies of Arizona and Utah. These concretion and shell beds are physically traceable farther landward (westward) into bioturbated, fossil-rich, transgressive lag deposits that bound 10-20m thick coarsening-upward progradational strand-plain deposits (parasequences) in southwestern Utah. We consider Milankovitch-style orbital forcing of climate and tectonically induced fluctuations in rates of foredeep basin subsidence as possible forcing mechanisms for these basinwide events. -from Authors

  19. Study on meter-scale cycles of the Lower Cretaceous Quantou Formation in SK-1 well%SK-1井下白垩统泉头组米级旋回研究

    Institute of Scientific and Technical Information of China (English)

    郭娟娟; 吴欣松; 潘建国; 魏东涛; 付建伟

    2012-01-01

    Based on the data of core and well logging of SK-1 well,this paper carried out the sedimentary microfacies identification,and divided cycle into third-order,fourth-order,fifth-order and meter-scale cycles.According to the cyclic sequence,this paper carried out the Fischer graphic analysis,and established cyclic stratigraphic framework.The absolute age ofQuantou Formation in SongliaoBasin was obtained by usingwell logging spectral analysis,and the cycle times were estimated.The result shows that the fifth-order cycle is 112 ka and fourth-order cycle is 379 ka,which is separately corresponding toMilankovitch eccentricity short circle 85~140 ka and Milankovitch eccentricity long circle 350~400 ka.The results coincide with the result of logging.This further illustrates that the forming of cycle sequence formation is controlled byMilankovitch cycle,which provides scientific foundation for the test of influencing factors of climate change in Cretaceous period.%通过对SK-1井泉头组岩心的详细观察与描述,并结合测井曲线特征,开展了泉头组沉积微相的识别,并在此基础上,划分了Ⅲ级、Ⅳ级、Ⅴ级及米级旋回。通过对所划分的旋回地层进行Fischer图解分析,建立了反映泉头组地层叠置关系的旋回地层格架。利用测井谱分析,结合前人分析测试得到的松辽盆地泉头组的绝对年龄,对各级旋回进行周期计算,发现Ⅴ级旋回周期约为112ka,Ⅳ级旋回周期约为379ka,分别与米兰科维奇偏心率短周期85~140ka和长周期350~400ka相对应,从而表明SK-1井旋回地层的形成受米兰科维奇旋回的控制。此研究结果为早白垩世气候变化对旋回地层的影响研究提供了科学依据。

  20. Analysis of Tenth-Year Students’ Eating Habits of a Technical High School in Pérez Zeledón Based on the Transversal Themes of the Program for Third Cycle of Costa Rica Basic General Education

    Directory of Open Access Journals (Sweden)

    José Miguel Pereira-Chaves

    2017-08-01

    Full Text Available The objective of this study was to diagnose the knowledge tenth-grade students have about eating habits and nutrition. This analysis reviews the relation between good nutrition and the transversal axes of the program of study for the third cycle of Costa Rica’s general basic education. Considering that healthy eating should not escape from the educational field, the nutritional values and eating habits should be inculcated to students, so that they can develop optimally in life. A survey containing 13 items with open and closed multiple-choice answers was applied to 30 tenth-grade students, and 18 teachers from a Professional Technical High School located in Pérez Zeledón, San José, Costa Rica. The main results showed the poor nutritional culture of the surveyed students in this educational center, and the lack of commitment of the teachers to mainstream healthy eating habits in their classes.

  1. 利用Matlab函数识别沉积物中的米兰柯维奇旋回信号%Recognition of Milankovitch Cycles in Sediments by Using Matlab Functions

    Institute of Scientific and Technical Information of China (English)

    赵庆乐; 张世红; 王婷婷; 吴怀春; 李海燕; 张元厚

    2010-01-01

    针对旋回分析中需要对数据进行的各种处理,利用Matlab中集成的滤波(filter)函数、插值(interp1)函数、求均值(mean)函数、去线性趋势(detrend)函数、求方差(variance)函数及谱分析(pwelch)函数等的组合,编制了识别沉积物中米兰柯维奇旋回信号的程序.选择窗口宽度(window)约等于有用信号中最低频率信号的波长、交叠点数(noverlap)为窗口宽度的50%、傅里叶变换的数据点数(nfft)大于全部采样数据的长度且为2的最小整数次幂时,可获得较好的谱估计结果.其不足之处是不能估计背景的红噪声谱及给出谱峰值的置信水平.

  2. 川东渝北飞仙关组的米兰克维奇周期及其应用%Analysis and Application of Milankovitch Cycles on Feixianguan Formation,Northeast Sichuan Basin,China

    Institute of Scientific and Technical Information of China (English)

    郑兴平; 罗平

    2004-01-01

    采用测井钍钾比指标的频谱分析方法识别出川东渝北下三叠统飞仙关组中的米兰克维奇周期,并认为其中的离心率周期表现较强,控制了飞仙关组的基准面旋回和沉积变化.尝试将飞仙关组划分为56个短离心率旋回,每个周期约10万年,厚度约3~15m,可为飞仙关组地层区域等时精细对比提供了一种基础依据.

  3. Basic principle of Milankovitch cycle and it's prospect in terrigenous lake basin analysis%米氏旋回基本原理及其在陆相湖盆分析中的应用前景

    Institute of Scientific and Technical Information of China (English)

    邱桂强; 刘军锷; 帅萍

    2001-01-01

    米氏旋回是指峰值时间跨度为20~500ka、日地天文轨道参数的周期性变化,以及由此产生的气候和沉积地层的旋回性变化.米氏旋回主要通过改变地球表面的太阳辐射能对气候变化进行控制,并对沉积作用产生重要的影响.通过沉积地层观测数据的时序分析可以重建米氏旋回,对地层的成因和过程进行研究.米氏旋回代表地层学和古气候学研究的前沿课题,不仅在深海沉积物的研究中得到了广泛应用,对陆相含油气盆地地层分析和油气储集层的预测也都具有重要意义.

  4. 柴达木盆地东部三湖地区四系米兰柯维奇旋回分析%Analysis of milankovitch cycles of quaternary in sanhu area ,eastern qaidam basin

    Institute of Scientific and Technical Information of China (English)

    王永军; 郭泽清; 刘卫红; 徐小林; 曾富英

    2007-01-01

    自然伽马曲线包含丰富的地质信息,能够很好地反映由气候变化引起的地层旋回.本文采用频谱分析对柴达木盆地三湖地区第四系自然伽马测井曲线进行了系统分析.作为频谱分析方法之一的快速傅里叶变换能够将自然伽马曲线从时间(深度)域转换为频率域,然后分析每一个峰值频率的波长及其相互之间的比率关系,寻找那些波长比率与米兰柯维奇周期比率相同或相似的频率,从而捕获高频旋回信息.研究结果表明第四系地层中很好地保存了高频的米兰柯维奇旋回,这样的沉积旋回主要由地球轨道的周期性变化而导致的古气候变化引起的.偏心率周期引起的地层旋回厚度变化范围在92.00~115.00 m之间,黄赤交角引起的地层旋回厚度变化范围在24.55~63.43 m之间,岁差引起的地层旋回厚度变化范围在16.8~26.35 m 之间.黄赤交角和岁差是影响该区米兰柯维奇旋回的主要因素,其中岁差的影响最大,而偏心率的影响最小.

  5. 米兰柯维奇旋回与高频波动周期的识别%Milankovitch cycles and the recognition of high-frequency wave period

    Institute of Scientific and Technical Information of China (English)

    齐永安; 王润怀; 潘结南

    2000-01-01

    运用频谱分析方法在塔里木盆地塔中地区志留系识别出米兰柯维奇旋回.对米氏旋回进行波动分析表明,高频率的5Ma周期波波动特征能够有效地解释生、储、盖演化.周期波表现为峰峰叠加,为储层发育期;周期波表现为谷谷叠加时,为盖层发育期.高频波由波峰→波谷过渡的特征,刚好对应层序地层学的海进体系域→高位体系域的变化.

  6. 鄂尔多斯盆地上三叠统延长组米兰科维奇旋回的确定%DEFINITION OF MILANKOVITCH CYCLES FOR YANGCHANG FORMATION OF THE UPPER TRIASSIC IN ORDOS BASIN

    Institute of Scientific and Technical Information of China (English)

    张小会; 赵重远

    2002-01-01

    由天体轨道周期变化引起的气候变化被广泛地记录在沉积地层中.自然伽马曲线很好地反映了气候变化引起的地层旋回.消除高频干扰和低频趋势以后,自然伽马曲线可以用来分析地层中的米兰科维奇旋回.对鄂尔多斯盆地陕15井中延长组按油层段进行系统分析,得出陕15井由偏心率周期引起的地层旋回厚度在9.6~18.75 m之间;地轴倾斜和气候岁差周期引起的旋回层厚度在1.18~6.82 m之间.各油层组的沉积速率变化在7.8~14.2 cm/ ka之间.

  7. 四川盆地东北地区长兴组米兰科维奇周期分析%Analysis of Milankovitch Cycles of the Changxing Formation in Northeastern Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    李凤杰; 郑荣才; 罗清林; 雷光明

    2007-01-01

    为了研究川东北地区上二叠统长兴组中的米兰科维奇周期,采用Matlab提供的快速傅立叶变换数学函数,对该区测井曲线的频谱进行了分析.结果表明:长兴组中广泛地保存着123,44.89,35.11,21.16和17.72 ka的米兰科维奇沉积周期;地层中的沉积旋回主要受古气候变化的控制,偏心率、地轴倾角和岁差周期引起的地层旋回厚度变化范围分别为:10.64~13.74 m;2.89~5.35 m;1.57~2.40 m,其中受偏心率周期的影响最大.不同测井曲线虽然对地层中物理参数的敏感程度不同,但是反映的地质信息是一致的,都能很好地反映由气候变化引起的地层旋回.Matlab中的数学函数,简化了数学运算的过程,为地质工作者定量研究地质问题提供了一条简明有效的途径.

  8. Analysis of Milankovitch Cycles of Yanchang Formation in Jing′an Oilfield%靖安油田延长组米兰柯维奇沉积旋回分析

    Institute of Scientific and Technical Information of China (English)

    李斌; 孟自芳; 李相博; 卢红选; 郑民

    2005-01-01

    对米兰柯维奇旋回理论进行了概述,认为米兰柯维奇天文轨道参数所诱导的旋回沉积序列普遍存在于地质记录中.用小波分析对鄂尔多斯盆地靖安油田延长组储层测井曲线数据进行了预处理,采用快速傅里叶变换(FFT)进行了频谱分析,发现该储层中的沉积旋回主要受古气候变化的控制,由此确定了储层旋回厚度变化的周期并分析了米兰柯维奇旋回各因素对延长组储层旋回的影响,其中偏心率对该区沉积旋回的影响最大.

  9. THE MILANKOVITCH THEORY OF PLEISTOCENE GLACIAL CYCLES:CHALLENGES AND CHANCES%米兰科维奇冰期旋回理论:挑战与机遇

    Institute of Scientific and Technical Information of China (English)

    丁仲礼

    2006-01-01

    米兰科维奇理论认为,北半球高纬夏季太阳辐射变化是驱动第四纪冰期旋回的主因.这个理论的核心是单一敏感区的触发驱动机制,即北半球高纬气候变化信号被放大、传输进而影响全球.最近,由于大量高分辨率及精确定年的气候变化记录的获得,从以下4个方面构成了对米氏理论的挑战:1)一些低纬地区并没有明显的10万年冰量周期,而是以2万年岁差周期为主,表明北半球冰盖的扩张、收缩变化并没有完全控制低纬区的气候变化;2)在最近几次冰消期时,南半球和低纬区的温度增高,要早于北半球冰盖的融化,表明冰消期的触发机制并非是北半球高纬夏季太阳辐射;3)大气CO2浓度在第2冰消期的增加同南极升温相一致,表明该时大气CO2浓度增加亦有可能早于北半球冰盖消融;4)南半球的末次冰盛期有可能早于北半球.这就说明单一敏感区触发驱动机制已难以圆满解释所有观察事实,天文因素控制下轨道尺度气候变化机制研究正面临理论突破的新需求和新机遇.

  10. 莺歌海盆地米兰科维奇周期分析——以乐东气田为例%Analysis of Milankovitch Cycles in Yinggehai Basin——a Case Study of Ledong Gas Field

    Institute of Scientific and Technical Information of China (English)

    彭志春; 杨丽

    2012-01-01

    为了定量认识莺歌海盆地浅层第四系乐东组与上第三系莺歌海组一段地层的沉积时间、沉积速率、高频层序发育等,文章运用米兰科维奇周期原理,采用Matlab提供的快速傅立叶变换数学函数,将自然伽马曲线转换到频率域,介绍如何捕获米氏旋回信息,并且根据捕获的信息计算了地层的沉积时间与沉积速率.结果表明,该区地层旋回厚度比与米兰科维奇周期比十分接近,高频旋回由米兰科维奇周期所控制,至莺歌海组一段一气组地层沉积持续时间为2.23 Ma,期间最大沉积速率达88.62 cm/ka.在此基础上定性的分析了该段地层沉积时期海平面的相对变化,据此能更好的指导该区的高频层序划分与对比,合理的推断沉积模式并预测储层发育段.

  11. Astronomical forcing and mathematical theory of glacial-interglacial cycles

    Directory of Open Access Journals (Sweden)

    A. V. Kislov

    2009-02-01

    Full Text Available There are three important features of a proxy time series recorded during the Late Pleistocene. They are: 1 100 000-year cycle as a dominant control of global glacial-interglacials through the late Quaternary, 2 fluctuations with periods of about 40 and 20 thousand years (their contribution to dispersion is no more than 20%, 3 ''Red-noise'' behavior of the time series. Direct influence of the insolation change created by fluctuations of the eccentricity is too weak to cause the observed 100 000-year climate fluctuations. Therefore, other mechanisms of such a rhythm are proposed. On the basis of the equation of the heat budget, the equation describing dynamics of zonally averaged temperature is developed. Various combinations of terms of this equation are discussed. They present a linear response to the Milankovitch periodicity, the Langeven stochastic equation, the equation of delay oscillator, the stochastic equation of spontaneous transitions, and the equation of stochastic resonance.

    Orbitally-induced changes in the solar energy flux received by the Earth play an important role as a mechanism starting process of climate changes which is supported and intensified by different feedbacks within the climate system. Positive anomalies of solar radiation serve as a mechanism causing reorganization of the climate only in rare cases when inclination of Earth axis of rotation increases and, simultaneously, perihelion takes place during the summer time (for the Northern Hemisphere.

  12. Paths and cycles of hypergraphs

    Institute of Scientific and Technical Information of China (English)

    王建方; Tony; T.Lee

    1999-01-01

    Hypergraphs are the most general structures in discrete mathematics. Acyclic hypergraphs have been proved very useful in relational databases. New systems of axioms for paths, connectivity and cycles of hypergraphs are constructed. The systems suit the structure properties of relational databases. The concepts of pseudo cycles and essential cycles of hypergraphs are introduced. They are relative to each other. Whether a family of cycles of a hypergraph is dependent or independent is defined. An enumeration formula for the maximum number of independent essential cycles of a hypergraph is given.

  13. Fes cycling

    Directory of Open Access Journals (Sweden)

    Berkelmans Rik

    2008-01-01

    Full Text Available Many research with functional electrical stimulation (FES has been done to regain mobility and for health benefits. Better results have been reported for FES-cycling than for FES-walking. The majority of the subjects during such research are people with a spinal cord injury (SCI, cause they often lost skin sensation. Besides using surface stimulation also implanted stimulators can be used. This solves the skin sensation problem, but needs a surgery. Many physiological effects of FES-cycling has been reported, e.g., increase of muscles, better blood flow, reduction of pressure ulcers, improved self-image and some reduction of bone mineral density (BMD loss. Also people with an incomplete SCI benefit by FES-cycling, e.g. cycling time without FES, muscle strength and also the walking abilities increased. Hybrid exercise gives an even better cardiovascular training. Presently 4 companies are involved in FES-cycling. They all have a stationary mobility trainer. Two of them also use an outdoor tricycle. One combined with voluntary arm cranking. By optimizing the stimulation parameters the power output and fatigue resistance will increase, but will still be less compared to voluntary cycling.

  14. Culture in cycles: considering H.T. Odum's 'information cycle'

    Science.gov (United States)

    Abel, Thomas

    2014-01-01

    'Culture' remains a conundrum in anthropology. When recast in the mold of 'information cycles,' culture is transformed. New fault lines appear. Information is splintered into parallel or nested forms. Dynamics becomes cycling. Energy is essential. And culture has function in a directional universe. The 'information cycle' is the crowning component of H.T. Odum's theory of general systems. What follows is an application of the information cycle to the cultural domains of discourse, social media, ritual, education, journalism, technology, academia, and law, which were never attempted by Odum. In information cycles, cultural information is perpetuated - maintained against Second Law depreciation. Conclusions are that culture is in fact a nested hierarchy of cultural forms. Each scale of information production is semi-autonomous, with its own evolutionary dynamics of production and selection in an information cycle. Simultaneously, each information cycle is channeled or entrained by its larger scale of information and ultimately human-ecosystem structuring.

  15. Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.

    Science.gov (United States)

    Abe-Ouchi, Ayako; Saito, Fuyuki; Kawamura, Kenji; Raymo, Maureen E; Okuno, Jun'ichi; Takahashi, Kunio; Blatter, Heinz

    2013-08-08

    The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere

  16. Glacial cycles

    DEFF Research Database (Denmark)

    Kaufmann, R. K.; Juselius, Katarina

    We use a statistical model, the cointegrated vector autoregressive model, to assess the degree to which variations in Earth's orbit and endogenous climate dynamics can be used to simulate glacial cycles during the late Quaternary (390 kyr-present). To do so, we estimate models of varying complexity...... and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduce glacial cycles. Rather, changes in solar insolation associated with changes in Earth's orbit are needed...

  17. Earth as diode: monsoon source of the orbital ~100 ka climate cycle

    Directory of Open Access Journals (Sweden)

    R. Y. Anderson

    2010-08-01

    Full Text Available A potential source for Earth's enigmatic ~100 ka climate cycle, which is found in many ancient geological records at low latitudes and also in the pacing of glaciation during the late Pleistocene, is traced to a climatic rectifying process inherent in the monsoon. Seasonal information needed to identify the rectifying mechanism is preserved within varves of a continuous, 200 ka recording of annual maximum surface temperature (Tmax from the equator of Western Pangea. Specific seasonal reactions recorded in varves show how the monsoon reacted to seasonal differences in insolation at equinox to produce a 11.7 ka semi-precession cycle in Tmax. At solstice, anti-phasing of insolation in the Northern and Southern Hemispheres, intensified and focused by a highly asymmetric Pangea relative to the equator, produced a strong equatorial maritime monsoon that performed a nonlinear rectifying function similar to that of a simple rectifying diode. Expressed in the resulting varve series are substantial cycles in Tmax of 100 ka, 23.4 ka, and 11.7 ka. Importantly, any external or internal forcing of the tropical (monsoon climate system at higher-than-orbital frequencies (e.g. solar, ENSO should also be amplified at Milankovitch frequencies by the monsoon.

  18. The 1,800-year oceanic tidal cycle: a possible cause of rapid climate change.

    Science.gov (United States)

    Keeling, C D; Whorf, T P

    2000-04-11

    Variations in solar irradiance are widely believed to explain climatic change on 20,000- to 100,000-year time-scales in accordance with the Milankovitch theory of the ice ages, but there is no conclusive evidence that variable irradiance can be the cause of abrupt fluctuations in climate on time-scales as short as 1,000 years. We propose that such abrupt millennial changes, seen in ice and sedimentary core records, were produced in part by well characterized, almost periodic variations in the strength of the global oceanic tide-raising forces caused by resonances in the periodic motions of the earth and moon. A well defined 1,800-year tidal cycle is associated with gradually shifting lunar declination from one episode of maximum tidal forcing on the centennial time-scale to the next. An amplitude modulation of this cycle occurs with an average period of about 5,000 years, associated with gradually shifting separation-intervals between perihelion and syzygy at maxima of the 1,800-year cycle. We propose that strong tidal forcing causes cooling at the sea surface by increasing vertical mixing in the oceans. On the millennial time-scale, this tidal hypothesis is supported by findings, from sedimentary records of ice-rafting debris, that ocean waters cooled close to the times predicted for strong tidal forcing.

  19. Happy Cycling

    DEFF Research Database (Denmark)

    Geert Jensen, Birgitte; Nielsen, Tom

    2013-01-01

    og Interaktions Design, Aarhus Universitet under opgave teamet: ”Happy Cycling City – Aarhus”. Udfordringen i studieopgaven var at vise nye attraktive løsningsmuligheder i forhold til cyklens og cyklismens integration i byrum samt at påpege relationen mellem design og overordnede diskussioner af...

  20. Glacial cycles

    DEFF Research Database (Denmark)

    Kaufmann, R. K.; Juselius, Katarina

    and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduce glacial cycles. Rather, changes in solar insolation associated with changes in Earth's orbit are needed...

  1. Associations between urban form and cycling

    DEFF Research Database (Denmark)

    Nielsen, Thomas Alexander Sick; Olafsson, Anton Stahl; Carstensen, Trine Agervig

    of National Travel Survey data indicated that established walkability factors such as density, connectivity and diversity are related to cycling, and that access to retail concentrations/centres, public transportation level-of-service, as well as competition between walking and cycling depending...... of cycling and the distance cycled. A high probability of cycling generally implies short cycling distances, which leads to non-uniform, non-monotonous relations between environmental indicators such as walkability and total cycling. Further analysis of primary data allowing a consideration of attitudes...

  2. Sulfur cycle

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.

    :1, the reductive assimilation of sulfate is less important than nitrate. Assimilatory reduction is common among organisms and does not lead to the production of sulfide. The eight-electron reduction of sulfate to sulfide pro- ceeds in different stages. As the ion...; Biogeochemical Approaches to Environmental Risk Assessment; Biogeochemical Models; Biomagnification; Carbon Cycle; Classification and Regression Trees; Climate Change 1: Short-Term Dynamics; Constructed Wetlands, Subsurface Flow; Constructed Wetlands, Surface...

  3. Quasi-100 ky glacial-interglacial cycles triggered by subglacial burial carbon release

    Directory of Open Access Journals (Sweden)

    N. Zeng

    2007-01-01

    Full Text Available A mechanism is proposed in which climate, carbon cycle and icesheets interact with each other to produce a feedback that can lead to quasi-100 ky glacial-interglacial cycles. A central process is the burial and preservation of organic carbon by icesheets which contributes to the observed glacial-interglacial CO2 change (the glacial burial hypothesis, Zeng, 2003. Allowing carbon cycle to interact with physical climate, here I further hypothesize that deglaciation can be triggered by the ejection of glacial burial carbon when a major icesheet grows to sufficiently large size after a prolonged glaciation so that subglacial transport becomes significant. Glacial inception may be initiated by CO2 drawdown due to a relaxation from a high but transient interglacial CO2 value as the land-originated CO2 invades into deep ocean via thermohaline circulation and CaCO3 compensation. Also important for glacial inception may be the CO2 uptake by vegetation and soil regrowth in the previously ice-covered regions. When tested in a fully coupled Earth system model with comprehensive carbon cycle components and semi-empirical physical climate components, it produced under certain parameter regimes self-sustaining glacial-interglacial cycles with durations of 93 ky, CO2 changes of 90 ppmv, temperature changes of 6°C. Since the 100 ky cycles can not be easily explained by the Milankovitch astronomical forcing alone, this carbon-climate-icesheet mechanism provides a strong feedback that could interact with external forcings to produce the major observed Quaternary climatic variations. It is speculated that some glacial terminations may be triggered by this internal feedback while others by orbital forcing. Some observable consequences are highlighted that may support or falsify the theory.

  4. What cycles are recorded in continental Most Basin (Czech Republic, late Burdigalian)?

    Science.gov (United States)

    Matys Grygar, Tomas; Mach, Karel; Laurin, Jiri

    2013-04-01

    Understanding to climate dynamics requires identification of orbital forcing as a piece of a jigsaw puzzle. High-frequency climate changes could be the reason of discrepancies among Miocene climate reconstructions from sediment archives. Nearly all continental sediment sequences have some repetitive patterns, of which causes can be manifold; orbital forcing (climatic cycles) is only one option. There are two main reasons for this uncertainty: 1) recording mechanisms of climate changes in a real sediment basin are site-specific and ambiguous (and usually not known, or not reported) and 2) autocyclic behaviour (inherent chaos) and tectonics can also produce repetitive patterns and statistics itself is not capable to reveal that their nature is not climatic. On the other hand, most paleontological climatic reconstructions have temporal resolution in order of Myr (or at best in tenths of Myr), which cannot really reflect the expected climate dynamics. We have studied about 250 m thick clastic syn-rift sediment sequence in the Most Basin in the Ohře Graben (Czech Republic). In the mature-rift stage, a basin-wide lake existed there for monotonous lacustrine mudstones) to C5Cr or C5Dr chrons in the late Burdigalian (there are no other plausible options respecting the small mammal biozone MN3a in the early rifting stage). The simplest interpretation of the Milankovitch cycles in our sediment succession is variability in precipitation in Central Europe at a scale of tens to hundreds kyr.

  5. Kinetic models of conjugated metabolic cycles

    Science.gov (United States)

    Ershov, Yu. A.

    2016-01-01

    A general method is developed for the quantitative kinetic analysis of conjugated metabolic cycles in the human organism. This method is used as a basis for constructing a kinetic graph and model of the conjugated citric acid and ureapoiesis cycles. The results from a kinetic analysis of the model for these cycles are given.

  6. Safe cycling!

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    The HSE Unit will be running a cycling safety campaign at the entrances to CERN's restaurants on 14, 15 and 16 May. Pop along to see if they can persuade you to get back in the saddle!   With summer on its way, you might feel like getting your bike out of winter storage. Well, the HSE Unit has come up with some original ideas to remind you of some of the most basic safety rules. This year, the prevention campaign will be focussing on three themes: "Cyclists and their equipment", "The bicycle on the road", and "Other road users". This is an opportunity to think about the condition of your bike as well as how you ride it. From 14 to 16 May, representatives of the Swiss Office of Accident Prevention and the Touring Club Suisse will join members of the HSE Unit at the entrances to CERN's restaurants to give you advice on safe cycling (see box). They will also be organising three activity stands where you can test your knowle...

  7. Variations of the Milankovitch frequencies in time

    Science.gov (United States)

    Loutre, Marie-France; Berger, A.

    1992-01-01

    The sensitivity of the amplitudes and frequencies in the development of the Earth's orbital and rotational elements involved in the astronomical theory of paleoclimates (eccentricity, obliquity, and climate precession), to the Earth-Moon distance and consequently to the length of the day and to the dynamical ellipticity of the Earth has been discussed for the last billions of years. The shortening of the Earth-Moon distance and of the length of the day, as well as the lengthening of the dynamical ellipticity of the Earth back in time induce a shortening of the fundamental astronomical periods for precession and obliquity. At the same time, the amplitudes of the different terms in the development of the obliquity are undergoing a relative enlargement of about 50 percent at 2 x 10(exp 9) yr BP but the independent term is increasing very weakly (less than 0.1 percent). In other words, the value of the obliquity, which lies within a range of 21.7 to 24.9 deg over the Quarternary was restricted to a range of 22.5 to 24.1 deg at 2 x 10(exp 9) yr BP. On the other hand, the amplitudes in the development of the climatic precession do not change. Moreover, these changes in the frequencies and amplitudes for both obliquity and climatic precession are larger for longer period terms. Finally, the periods in the eccentricity development are not influenced by the variation of the lunar distance. But the motion of the solar system, especially of the inner planets, was shown to be chaotic. It means that it is impossible to compute the exact motion of the planets over more than about 100 Myr, and the fundamental frequencies of the systems are not fixed quantities, but are slowly varying with time. As long as we consider the most important terms, the maximum deviation from the present-day value of the 19-kyr precessional period due to the chaotic motion of the solar system only does not reach more than a few tens of years around 80 Myr BP. Therefore the shortening of the obliquity and climatic precession periods is mostly driven by the change in the lunar distance and the consequent variations in the dynamical ellipticity of the Earth's angular speed. At first sight, the deviation in the period for the eccentricity can be neglected, as the chaotic behavior of the solar system implies a relative change of the main periods by less than 0.2 percent, 1.4 percent, and 1.9 percent respectively, this maximum change being achieved around 80 Myr BP. This implies, in particular, that the eccentricity periods for Quarternary climate studies may be considered more or less constant for pre-Quaternay times and equal to their Quaternary values.

  8. Hemipelagic shelf sedimentation and climatic cycles: the basal Jurassic (Blue Lias) of South Britain

    Science.gov (United States)

    Weedon, G. P.

    1986-01-01

    The sedimentology, cyclicity and hiatuses of the Blue Lias Formation (basal Jurassic) were investigated at five localities in South Britain. Most carbonate mud, which is the dominant carbonate component, has been neomorphosed to microspar. However, carbonate mud was apparently supplied by coccoliths in zooplankton faecal pellets, suggesting hemipelagic sedimentation. Clay is assumed to have been supplied by rivers. The three sediment types involved reflect cyclic changes in bottom-water oxygenation levels combined with changes in the clay-to-carbonate mud ratio. Walsh power spectra have been applied for the first time to measured sections in order to investigate the control of cyclicity. This application is analogous to palaeoclimatological studies of Pleistocene oxygen-isotope (ice-volume) records. The spectra show that 1 or 2 sedimentary cycles, of constant thickness, occur in four out of five sections, each of which represents several million years. The maximum possible duration of these cycles is too short for their generation by sea-level changes. Their regularity, stability and order of duration (tens of thousands of years) are consistent with the hypothesis of sedimentary cyclicity controlled by climatic change, itself forced by orbital changes in insolation (Milankovitch theory). The duration of both cycles recognised is less than 93,000 years (93 ka) and may record changes in orbital precession (21 ka) and obliquity (41 ka). Assuming that one ammonite zone represents 1 Ma, comparison of the longest-possible with the implied durations of the cycles, suggests that the sections are at best 20-40% complete. Loss of sediment may have occurred during winter storms or hurricanes. A model relating the sedimentary cycles to changes in the volume of runoff is proposed.

  9. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan Yang; Dan JLehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is dififcult to explain cycles formed in a greenhouse climate when eustasy is minimal. We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou, South China, were formed by hierarchical carbonate productivity variations. Most of the 149 shallowing-upward cycles are typically terminated by lfooding over intertidal facies and con-tain rare supratidal facies and no prolonged subaerial exposure. Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations, which caused variations in benthic sediment productivity in the subtidal carbon-ate factory. The perturbations may be driven by changes in salinity and degree of eutrophica-tion, or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop. They were modulated by Milankovitch orbitally-driven climatic and oceano-graphic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles. A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant sub-sidence and no sea-level lfuctuation.

  10. Peritidal carbonate cycles induced by carbonate productivity variations:A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Institute of Scientific and Technical Information of China (English)

    Wan; Yang; Dan; J.Lehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity,but is difficult to explain cycles formed in a greenhouse climate when eustasy is minimal.We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou,South China,were formed by hierarchical carbonate productivity variations.Most of the 149 shallowing-upward cycles are typically terminated by flooding over intertidal facies and contain rare supratidal facies and no prolonged subaerial exposure.Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations,which caused variations in benthic sediment productivity in the subtidal carbonate factory.The perturbations may be driven by changes in salinity and degree of eutrophication,or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop.They were modulated by Milankovitch orbitally-driven climatic and oceanographic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles.A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant subsidence and no sea-level fluctuation.

  11. OREGANO_VE: a new parallelised 3D solver for the general (non-)linear Maxwell visco-elastic problem: validation and application to the calculation of surface deformation in the earthquake cycle

    Science.gov (United States)

    Yamasaki, Tadashi; Houseman, Gregory; Hamling, Ian; Postek, Elek

    2010-05-01

    We have developed a new parallelized 3-D numerical code, OREGANO_VE, for the solution of the general visco-elastic problem in a rectangular block domain. The mechanical equilibrium equation is solved using the finite element method for a (non-)linear Maxwell visco-elastic rheology. Time-dependent displacement and/or traction boundary conditions can be applied. Matrix assembly is based on a tetrahedral element defined by 4 vertex nodes and 6 nodes located at the midpoints of the edges, and within which displacement is described by a quadratic interpolation function. For evaluating viscoelastic relaxation, an explicit time-stepping algorithm (Zienkiewicz and Cormeau, Int. J. Num. Meth. Eng., 8, 821-845, 1974) is employed. We test the accurate implementation of the OREGANO_VE by comparing numerical and analytic (or semi-analytic half-space) solutions to different problems in a range of applications: (1) equilibration of stress in a constant density layer after gravity is switched on at t = 0 tests the implementation of spatially variable viscosity and non-Newtonian viscosity; (2) displacement of the welded interface between two blocks of differing viscosity tests the implementation of viscosity discontinuities, (3) displacement of the upper surface of a layer under applied normal load tests the implementation of time-dependent surface tractions (4) visco-elastic response to dyke intrusion (compared with the solution in a half-space) tests the implementation of all aspects. In each case, the accuracy of the code is validated subject to use of a sufficiently small time step, providing assurance that the OREGANO_VE code can be applied to a range of visco-elastic relaxation processes in three dimensions, including post-seismic deformation and post-glacial uplift. The OREGANO_VE code includes a capability for representation of prescribed fault slip on an internal fault. The surface displacement associated with large earthquakes can be detected by some geodetic observations

  12. Quadratic reactivity fuel cycle model

    Energy Technology Data Exchange (ETDEWEB)

    Lewins, J.D.

    1985-11-01

    For educational purposes it is highly desirable to provide simple yet realistic models for fuel cycle and fuel economy. In particular, a lumped model without recourse to detailed spatial calculations would be very helpful in providing the student with a proper understanding of the purposes of fuel cycle calculations. A teaching model for fuel cycle studies based on a lumped model assuming the summability of partial reactivities with a linear dependence of reactivity usefully illustrates fuel utilization concepts. The linear burnup model does not satisfactorily represent natural enrichment reactors. A better model, showing the trend of initial plutonium production before subsequent fuel burnup and fission product generation, is a quadratic fit. The study of M-batch cycles, reloading 1/Mth of the core at end of cycle, is now complicated by nonlinear equations. A complete account of the asymptotic cycle for any order of M-batch refueling can be given and compared with the linear model. A complete account of the transient cycle can be obtained readily in the two-batch model and this exact solution would be useful in verifying numerical marching models. It is convenient to treat the parabolic fit rho = 1 - tau/sup 2/ as a special case of the general quadratic fit rho = 1 - C/sub tau/ - (1 - C)tau/sup 2/ in suitably normalized reactivity and cycle time units. The parabolic results are given in this paper.

  13. Business Cycles in Developing Countries

    DEFF Research Database (Denmark)

    Rand, John; Tarp, Finn

    2002-01-01

    This paper demonstrates that developing countries differ considerably from their developed counterparts when focus is on the nature and characteristics of short run macroeconomic fluctuations. Cycles are generally shorter, and the stylized facts of business cycles across countries are more diverse...... than those of the rather uniform industrialized countries. Supply-side models are generally superior in explaining changes in output, but a “one-size fits all” approach in formulating policy is inappropriate. Our results also illustrate the critical importance of understanding business regularities...... as a stepping-stone in the process of designing appropriate stabilization policy and macroeconomic management in developing countries....

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

    Science.gov (United States)

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

    2014-05-02

    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.

  15. Oceanic mechanisms for amplification of the 23,000-year ice-volume cycle.

    Science.gov (United States)

    Ruddiman, W F; McIntyre, A

    1981-05-08

    Situated adjacent to the largest Northern Hemispher ice sheets of the ice ages, the mid-latitude North Atlantic Ocean has an important role in the earth's climate history. It provides a significant local source of moisture for the atmosphere and adjacent continents, forms a corridor that guides moisture-bearing storms northward from low latitudes, and at times makes direct contact along its shorelines with continental ice masses. Evidence of major ice-ocean-air interactions involving the North Atlantic during the last 250,000 years is summarized. Outflow of icebergs and meltwater initially driven by summer insolation over the ice sheets affects midlatitude ocean temperatures, summer heat storage, winter sea-ice extent, and global sea level. These oceanic responses in turn influence the winter moisture flux back to the ice sheets, as well as ablation of land ice by calving. Spectral data indicate that the oceanic moisture and sea-level feedbacks, in part controlled by glacial melt products, amplify Milankovitch (insolation) forcing of the volumetrically dominant mid-latitude ice sheets at the 23,000-year precessional cycle.

  16. Peut-on évaluer le rôle de la sédimentation sur l'effet de serre à l'échelle de temps des cycles orbitaux ?Can the role of sedimentation in the greenhouse effect at the time scale of orbital cycles be evaluated?

    Science.gov (United States)

    Bertrand, Philippe

    The evolution of the atmospheric CO 2 content is partly a response to the lack of balance between oceanic sedimentation and continental weathering, because the oceanic C reservoir tends to balance net inputs or losses from slow processes by rapid exchanges with the atmospheric reservoir. This response strongly depends on both amplitudes and time scales of the related processes. At Milankovitch or lower time scales, global models generally do neglect organic matter fossilisation, but such an assumption is only valid for oligotrophic systems. In eutrophic or mesotrophic systems, organic matter is not negligible and should be considered relatively to the carbonate sedimentation in order to know whether the impact of the sedimentation was a source or a sink for atmospheric CO 2. To cite this article: P. Bertrand, C. R. Geoscience 334 (2002) 521-528.

  17. Bipolar mood cycles and lunar tidal cycles.

    Science.gov (United States)

    Wehr, T A

    2017-01-24

    In 17 patients with rapid cycling bipolar disorder, time-series analyses detected synchronies between mood cycles and three lunar cycles that modulate the amplitude of the moon's semi-diurnal gravimetric tides: the 14.8-day spring-neap cycle, the 13.7-day declination cycle and the 206-day cycle of perigee-syzygies ('supermoons'). The analyses also revealed shifts among 1:2, 1:3, 2:3 and other modes of coupling of mood cycles to the two bi-weekly lunar cycles. These shifts appear to be responses to the conflicting demands of the mood cycles' being entrained simultaneously to two different bi-weekly lunar cycles with slightly different periods. Measurements of circadian rhythms in body temperature suggest a biological mechanism through which transits of one of the moon's semi-diurnal gravimetric tides might have driven the patients' bipolar cycles, by periodically entraining the circadian pacemaker to its 24.84-h rhythm and altering the pacemaker's phase-relationship to sleep in a manner that is known to cause switches from depression to mania.Molecular Psychiatry advance online publication, 24 January 2017; doi:10.1038/mp.2016.263.

  18. ON THE LIMIT CYCLES OF PLANAR AUTONOMOUS SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The authors investigate the global properties of general autonomous systems on the plane and establish criteria for the nonexistence, existence and uniqueness of limit cycles. As application examples, the limit cycles for some polynomial systems are studied.

  19. LIFE CYCLE ASSESSMENT: PRINCIPLES AND PRACTICE

    Science.gov (United States)

    The following document provides an introductory overview of Life Cycle Assessment (LCA) and describes the general uses and major components of LCA. This document is an update and merger of two previous EPA documents on LCA ("Life Cycle Assessment: Inventory Guidelines and Princip...

  20. Few-optical-cycle dissipative solitons

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, H [Laboratoire de Photonique d' Angers EA 4464, Universite d' Angers, 2 Bd. Lavoisier, 49045 Angers Cedex 01 (France); Mihalache, D, E-mail: herve.leblond@univ-angers.f [Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, Magurele-Bucharest, 077125 (Romania)

    2010-09-17

    By using a powerful reductive perturbation technique, or multiscale analysis, a generalized modified Korteweg-de Vries partial differential equation is derived, which describes the physics of few-optical-cycle dissipative solitons beyond the slowly varying envelope approximation. Numerical simulations of the formation of stable dissipative solitons from arbitrary breather-like few-cycle pulses are also given.

  1. General formation of three-dimensional (3D) interconnected MxSy (M = Ni, Zn, and Fe)-graphene nanosheets-carbon nanotubes aerogels for lithium-ion batteries with excellent rate capability and cycling stability

    Science.gov (United States)

    Wang, Xiujuan; Liu, Xiaojie; Wang, Gang; Zhou, Yixuan; Wang, Hui

    2017-02-01

    Metal sulfides have a highly promising potential as anode materials for next-generation lithium-ion batteries (LIBs) due to their environmental friendliness, abundant resources, and low-cost. Unfortunately, the implementation of such novel anodes is severely hindered by their low electronic conductivity and large volume expansion during the repetitive lithiation/delithiation process. Herein, we report a specifically designed anode structure to overcome these obstacles, that is, to incorporate MxSy (M = Ni, Zn, and Fe) with graphene nanosheets (GNS) and carbon nanotubes (CNTs) to form three-dimensional interconnected MxSy-graphene nanosheets-carbon nanotubes aerogels. Morphology and structure results confirm that MxSy particles were uniformly and closely attached on the 3D complex network structure of GNS-CNT. As a result, when used as anode materials for half and full LIBs, the MxSy-GNS-CNT aerogels exhibit remarkable high reversible capacities, ultra-long cycle life, and super high rate performance (For example, the NiS-GNS-CNT, ZnS-GNS-CNT, and FeS2-GNS-CNT aerogels could deliver high capacities of 735, 800, and 850 mAh g-1 after 100 cycles, respectively). Our results indicate that 3D interconnected MxSy-GNS-CNT aerogels are promising anode materials for the next generation LIBs with high-performance.

  2. Driving forces of Indian summer monsoon on Milankovitch and sub-Milankovitch time scales: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    and deep water circulation changes drive the variability of southwest (SW) monsoon in the Indian subcontinent. Different forcing factors act on different time scales. Arabian Sea sediments consist of distinct fauna that are endemic to areas of upwelling...

  3. The Solar Cycle

    CERN Document Server

    Hathaway, David H

    2015-01-01

    The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

  4. The Solar Cycle.

    Science.gov (United States)

    Hathaway, David H

    The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

  5. General Dentist

    Science.gov (United States)

    ... Some general dentists work in government health services, research programs, higher education, corporations and even the military. ?xml:namespace> What kind of procedures do general dentists provide? ?xml:namespace> Many general dentists are ...

  6. Geomicrobiological cycling of antimony

    Science.gov (United States)

    Kulp, T. R.; Terry, L.; Dovick, M. A.; Braiotta, F.

    2013-12-01

    Microbiologically catalyzed oxidation and reduction of toxic metalloids (e.g., As, Se, and Te) generally proceeds much faster than corresponding abiotic reactions. These microbial transformations constitute biogeochemical cycles that control chemical speciation and environmental behavior of metalloids in aqueous environments. Particular progress has been made over the past two decades in documenting microbiological biotransformations of As, which include anaerobic respiratory reduction of As(V) to As(III), oxidation of As(III) to As(V) linked to chemoautotrophy or photoautotrophy, and cellular detoxification pathways. By contrast, microbial interactions with Sb, As's group 15 neighbor and a toxic element of emerging global concern, are poorly understood. Our work with sediment microcosms, enrichment cultures, and bacterial isolates suggests that prokaryotic metabolisms may be similarly important to environmental Sb cycling. Enrichment cultures and isolates from a Sb-contaminated mine site in Idaho exhibited Sb(V)-dependent heterotrophic respiration under anaerobic conditions and Sb(III)-dependent autotrophic growth in the presence of air. Live, anoxic cultures reduced 2 mM Sb(V) to Sb(III) within 5 d, while no activity occurred in killed controls. Sb(V) reduction was stimulated by lactate or acetate and was quantitatively coupled to the oxidation of lactate. The oxidation of radiolabeled 14C-acetate (monitored by GC-GPC) demonstrated Sb(V)-dependent oxidation to 14CO2, suggesting a dissimilatory process. Sb(V) dependent growth in cultures was demonstrated by direct counting. Microbiological reduction of Sb(V) also occurred in anerobic sediment microcosms from an uncontaminated suburban lake, but did not appear to be linked to growth and is interpreted as a mechanism of biological detoxification. Aerobic microcosms and cultures from the Idaho mine oxidized 2 mM Sb(III) to Sb(V) within 7 d and coupled this reaction to cell growth quantified by direct counting. An

  7. foF2 vs solar indices for the Rome station: Looking for the best general relation which is able to describe the anomalous minimum between cycles 23 and 24

    Science.gov (United States)

    Perna, L.; Pezzopane, M.

    2016-10-01

    Analyses of the dependence of the F2layer critical frequency, foF2, on five widely used solar activity indices (F10.7, Lym-α, MgII, R and EUV0.1-50)are carried out considering noon values manually validated at the ionospheric station of Rome (41.8°N, 12.5°E, Italy) between January 1976 and December 2013, a period of time covering the last three solar cycles and including the prolonged and anomalous minimum of solar cycle 23/24 (years 2008-2009). After applying a 1-year running mean to both foF2 and solar activity indices time series, a second order polynomial fitting proves to perform better than a linear one, and this is specifically due to the very low solar activity of the last solar minimum and to the remaining saturation effect characterizing the high solar activity. A comparison between observed and synthetic foF2 values, the latter calculated by using the analytical relations found for every index, and some considerations made on the R parameter introduced by Solomon et al. (2013), suggest that MgII is the best index to describe the dependence of foF2 on the solar activity. Three main reasons justify this result: (1) the good sensibility of MgII to the variations of foF2 for low solar activity; (2) the reduced saturation effect characterizing MgII at high solar activity; (3) the poor influence of the hysteresis effect characterizing MgII at medium solar activity. On the other hand, the F10.7 index, widely used as input parameter for numerous ionospheric models, does not represent properly the last minimum; specifically, it is not able to describe the variations of foF2 under a solar activity level of F10.7=82·10-22 [J Hz-1 s-1 m-2].

  8. Generalizations of Brandl's theorem on Engel length

    Science.gov (United States)

    Quek, S. G.; Wong, K. B.; Wong, P. C.

    2013-04-01

    Let n Engel cycle generated by g and h. The length of the Engel cycle is m-n. A group G is said to have Engel length r, if all the length of the Engel cycles in G divides r. In this paper we discuss the Brandl's theorem on Engel length and give some of its generalizations.

  9. Solar cycle 25: another moderate cycle?

    CERN Document Server

    Cameron, Robert H; Schuessler, Manfred

    2016-01-01

    Surface flux transport simulations for the descending phase of cycle 24 using random sources (emerging bipolar magnetic regions) with empirically determined scatter of their properties provide a prediction of the axial dipole moment during the upcoming activity minimum together with a realistic uncertainty range. The expectation value for the dipole moment around 2020 $(2.5\\pm1.1\\,$G) is comparable to that observed at the end of cycle 23 (about $2\\,$G). The empirical correlation between the dipole moment during solar minimum and the strength of the subsequent cycle thus suggests that cycle 25 will be of moderate amplitude, not much higher than that of the current cycle. However, the intrinsic uncertainty of such predictions resulting from the random scatter of the source properties is considerable and fundamentally limits the reliability with which such predictions can be made before activity minimum is reached.

  10. Proliferation in cycle

    Energy Technology Data Exchange (ETDEWEB)

    Piao Yunsong [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China)], E-mail: yspiao@gucas.ac.cn

    2009-06-15

    In the contracting phase with w{approx_equal}0, the scale invariant spectrum of curvature perturbation is given by the increasing mode of metric perturbation. In this Letter, it is found that if the contracting phase with w{approx_equal}0 is included in each cycle of a cycle universe, since the metric perturbation is amplified on super horizon scale cycle by cycle, after each cycle the universe will be inevitably separated into many parts independent of one another, each of which corresponds to a new universe and evolves up to next cycle, and then is separated again. In this sense, a cyclic multiverse scenario is actually presented, in which the universe proliferates cycle by cycle. We estimate the number of new universes proliferated in each cycle, and discuss the implications of this result.

  11. Self-Fulfilling Credit Cycles

    OpenAIRE

    Costas Azariadis; Leo Kaas

    2012-01-01

    This paper argues that self-fulfilling beliefs in credit conditions can generate endogenously persistent business cycle dynamics. We develop a tractable dynamic general equilibrium model with idiosyncratic firm productivity shocks. Capital from less productive firms is lent to more productive ones in the form of credit secured by collateral and also as unsecured credit based on reputation. A dynamic complementarity between current and future credit constraints permits uncorrelated sunspot sho...

  12. Cycling in Sydney, Australia

    Directory of Open Access Journals (Sweden)

    Alexis Zander

    2013-01-01

    Full Text Available Introduction. Cycling can be an enjoyable way to meet physical activity recommendations and is suitable for older people; however cycling participation by older Australians is low. This qualitative study explored motivators, enablers, and barriers to cycling among older people through an age-targeted cycling promotion program. Methods. Seventeen adults who aged 50–75 years participated in a 12-week cycling promotion program which included a cycling skills course, mentor, and resource pack. Semistructured interviews at the beginning and end of the program explored motivators, enablers, and barriers to cycling. Results. Fitness and recreation were the primary motivators for cycling. The biggest barrier was fear of cars and traffic, and the cycling skills course was the most important enabler for improving participants’ confidence. Reported outcomes from cycling included improved quality of life (better mental health, social benefit, and empowerment and improved physical health. Conclusions. A simple cycling program increased cycling participation among older people. This work confirms the importance of improving confidence in this age group through a skills course, mentors, and maps and highlights additional strategies for promoting cycling, such as ongoing improvement to infrastructure and advertising.

  13. Life cycle assessment (LCA)

    DEFF Research Database (Denmark)

    Thrane, Mikkel; Schmidt, Jannick Andresen

    2004-01-01

    The chapter introduces Life Cycle Assessment (LCA) and its application according to the ISO 1404043 standards.......The chapter introduces Life Cycle Assessment (LCA) and its application according to the ISO 1404043 standards....

  14. Life cycle assessment (LCA)

    DEFF Research Database (Denmark)

    Thrane, Mikkel; Schmidt, Jannick Andresen

    2004-01-01

    The chapter introduces Life Cycle Assessment (LCA) and its application according to the ISO 1404043 standards.......The chapter introduces Life Cycle Assessment (LCA) and its application according to the ISO 1404043 standards....

  15. Menstrual Cycle Problems

    Science.gov (United States)

    ... Read MoreDepression in Children and TeensRead MoreBMI Calculator Menstrual Cycle ProblemsFrom missed periods to painful periods, menstrual cycle problems are common, but usually not serious. Follow ...

  16. Relations between tautological cycles on Jacobians

    NARCIS (Netherlands)

    Moonen, B.

    2009-01-01

    We study tautological cycle classes on the Jacobian of a curve. We prove a new result about the ring of tautological classes on a general curve that allows, among other things, easy dimension calculations and leads to some general results about the structure of this ring. Further we lift a result of

  17. HIV Life Cycle

    Science.gov (United States)

    HIV Overview The HIV Life Cycle (Last updated 9/13/2016; last reviewed 9/8/2016) Key Points HIV gradually destroys the immune ... life cycle. What is the connection between the HIV life cycle and HIV medicines? Antiretroviral therapy (ART) ...

  18. Cycling To Awareness.

    Science.gov (United States)

    Kozak, Stan

    1999-01-01

    Encourages environmental and outdoor educators to promote bicycling. In the community and the curriculum, cycling connects environmental issues, health and fitness, law and citizenship, appropriate technology, and the joy of being outdoors. Describes the Ontario Cycling Association's cycling strategy and its four components: school cycling…

  19. Hereditary urea cycle abnormality

    Science.gov (United States)

    ... vitro so the specific genetic cause is known. Teamwork between parents, the affected child, and doctors can help prevent severe illness. Alternative Names Abnormality of the urea cycle - hereditary; Urea cycle - hereditary abnormality Images Male urinary system Urea cycle References Lichter-Konecki ...

  20. SIRTF Cycle-1 Research Opportunities

    Science.gov (United States)

    Soifer, B. T.; Bicay, M. D.

    2003-12-01

    The Space InfraRed Telescope Facility (SIRTF), the fourth and final element in NASA's family of Great Observatories, was successfully launched into an Earth-trailing heliocentric orbit on August 25, 2003. The SIRTF Science Center (SSC) at Caltech is now soliciting Cycle-1 research proposals from the worldwide scientific community. Proposals must be submitted electronically to the SSC by February 14, 2004. A preliminary version of the Cycle-1 Call for Proposals (CP) was issued by the SSC in November 2002. A CP Update and supporting technical documentation, which incorporates the on-orbit performance of the observatory, were released in December 2003. Investigations may be proposed for new SIRTF observations, through the General Observer (GO) program, or for archival research. About 3700 hours of observing time is being offered for the Cycle-1 GO Program, in small (less than 50 hours) and medium (50 to 200 hours) categories. More than \\15 million in NASA data analysis support is available to qualified GO investigators. For GO proposals, a detailed list of proposed observations, generated by the SIRTF Planning Observations Tool, must accompany the research proposal. The Archival Research (AR) Program in Cycle-1 is limited to the analysis of data from the First-Look Survey, a 100-hour program to be executed by the SSC at the start of the science mission. Up to \\750,000 in NASA data analysis support is available to qualified AR investigators. All documents supporting the Cycle-1 solicitation are available online in the Proposal Kit section of the SSC public Web site (http://sirtf.caltech.edu/SSC/). Questions pertaining to the Cycle-1 CP should be sent electronically to the SSC HelpDesk at sirtf@ipac.caltech.edu. SIRTF is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

  1. Palaeoclimatic Cycles,Global Environmental Changes and New Glacial Periods Induced by the Impact of Extraterrestrial Bodies

    Institute of Scientific and Technical Information of China (English)

    王世杰; 欧阳自远; 等

    1999-01-01

    In terms of Earth-Sun geometry,the Milankovitch theory has successfully explained most of the cyclie palaeoclimatic variations during the history of the Earth,especially in the Quaternary.In this paper,the authors suggest that the impact of extraterrestrial bodies on the Earth may be another mechanism to cause palaeoclimatic cycles,global environmental changes and new glacial periods,Based on geological and geochemical records in the boundary layers produced by six huge Cenozoic bolide-impact events(65,34,15,2.4,1.1,0.73Ma B.P.),including those at 34,15,1.1and 0.73MaB.P.which are represented by four famous tektite-strewn fields,the process and mechanics of palaeoclimatic cycles and global environmental eatastrophes induced by extraterrestrial impact are discussed in detail.Impact-generated dust.soot and aerosol floating in the staratosphere could result in short-term(<1year),rapid drop in tempeature immediately after impact.Through self-regulation of the Earth's climate system,the temperature at the surface slowly went up within 100a and maintained stable for a long time at 250K.If there were no other factors leading to the break-down of the nely-established equilibrium,a new glaciel peood would be initiated.Estimating from the thickess of δ13C and δ18O anomalies in sediments across the impact boundary layer and deposition rate,the duration of two stages of the palaeoclimate cycle in the form of cold weather-greenhouse effect-normal weather war 104-105a ,respectively.The conclusion deduced from the above model is supported by palaeotemperature change recorded by oxygen isotope in sediments across the impact boundary layer.

  2. Solar storms, cycles and topology

    Directory of Open Access Journals (Sweden)

    Lundstedt H.

    2010-12-01

    Full Text Available Solar storms are produced due to plasma processes inside and between coronal loops. These loops are topologically examined using knot and braid theory. Solar cycles are topologically explored with a complex generalization of the three ordinary differential equations studied by Lorenz. By studying the Poincaré map we give numerical evidence that the flow has an attractor with fractal structure. The period is defined as the time needed for a point on a hyperplane to return to the hyperplane again. The periods are distributed in an interval. For large values of the Dynamo number there is a long tail toward long periods and other interesting comet-like features. We also found a relationship between the intensity of a cycle and the length for the previous cycle. Maunder like minima are also appearing. These general relations found for periods can further be physically interpreted with improved helioseismic estimates of the parameters used by the dynamical systems. Solar Dynamic Observatory is expected to offer such improved measurements.

  3. Development and Actuality of Life Cycle Cost Technique in China

    Institute of Scientific and Technical Information of China (English)

    GENG Jun-bao; JIN Jia-shan; LUO Yun; WU Yi-liang

    2012-01-01

    Life cycle cost technique is a powerful tool to make a scientific decision and a useful method of advancing the continuable development of the society. In this paper, development course, application actuality and up-to-date research trends of life cycle cost technique in China are summarized. Some suggestions are given on how to general- ize the application of life cycle cost technique which are used as the reference to study life cycle cost technique.

  4. Generalized product

    OpenAIRE

    Greco,Salvatore; Mesiar, Radko; Rindone, Fabio

    2014-01-01

    Aggregation functions on [0,1] with annihilator 0 can be seen as a generalized product on [0,1]. We study the generalized product on the bipolar scale [–1,1], stressing the axiomatic point of view. Based on newly introduced bipolar properties, such as the bipolar increasingness, bipolar unit element, bipolar idempotent element, several kinds of generalized bipolar product are introduced and studied. A special stress is put on bipolar semicopulas, bipolar quasi-copulas and bipolar copulas.

  5. Generalized product

    OpenAIRE

    Greco, Salvatore; Mesiar, Radko; Rindone, Fabio

    2014-01-01

    Aggregation functions on [0,1] with annihilator 0 can be seen as a generalized product on [0,1]. We study the generalized product on the bipolar scale [–1,1], stressing the axiomatic point of view. Based on newly introduced bipolar properties, such as the bipolar increasingness, bipolar unit element, bipolar idempotent element, several kinds of generalized bipolar product are introduced and studied. A special stress is put on bipolar semicopulas, bipolar quasi-copulas and bipolar copulas.

  6. 40 CFR 86.005-1 - General applicability.

    Science.gov (United States)

    2010-07-01

    ... subpart generally apply to 2005 and later model year new Otto-cycle heavy-duty engines used in incomplete..., vehicle class, motor fuel, engine type, or other distinguishing characteristics, the limited applicability... generally apply to 2000 and earlier model year new Otto-cycle and diesel-cycle light-duty vehicles, 2000...

  7. Driving and engine cycles

    CERN Document Server

    Giakoumis, Evangelos G

    2017-01-01

    This book presents in detail the most important driving and engine cycles used for the certification and testing of new vehicles and engines around the world. It covers chassis and engine-dynamometer cycles for passenger cars, light-duty vans, heavy-duty engines, non-road engines and motorcycles, offering detailed historical information and critical review. The book also provides detailed examples from SI and diesel engines and vehicles operating during various cycles, with a focus on how the engine behaves during transients and how this is reflected in emitted pollutants, CO2 and after-treatment systems operation. It describes the measurement methods for the testing of new vehicles and essential information on the procedure for creating a driving cycle. Lastly, it presents detailed technical specifications on the most important chassis-dynamometer cycles around the world, together with a direct comparison of those cycles.

  8. Mid-Pliocene onset of eccentricity cycles in the Zhada Basin, southwestern Tibetan Plateau.

    Science.gov (United States)

    Saadeh, C. M.; Saylor, J. E.; Shanahan, T. M.; Nie, J.

    2015-12-01

    Changes in the Asian Monsoon driven by Tibetan Plateau uplift have been invoked to explain late Miocene-Pliocene biological turnover and increases in erosion and sediment accumulation. However, documentation of pre-Miocene uplift of the plateau and evidence for early appearance of the Asian Monsoon system has called these conclusions into question. We present a high-resolution, long-term record of environmental change at 3.5-4.5 km essential to understanding the impact and causes of monsoon variation. The O and C isotopic record of authigenic carbonate in 566 samples from the Zhada Basin extends from 8.99 to 1.75 Ma. Both the δ18O and stratigraphic record indicate long-term changes in basin hydrology which may reflect the impact of regional tectonics on drainage reorganization. These long-term changes are characterized by an onset of lacustrine deposition coupled with an increase in mean δ18O values at 6.11 Ma followed by a return to palustrine/fluvial deposition and a decrease in mean δ18O values at 3.24 Ma. These Miocene-early Pleistocene Zhada Basin results mimic late Pleistocene-Holocene paleoclimatic records across the Tibetan Plateau suggesting similar driving mechanisms. Frequency analysis of the δ18O record reveals that Milankovitch cycles are recorded in the Zhada Basin; suggesting that insolation-driven climate change drove high-frequency environmental changes in the southern Tibetan Plateau. Counterintuitively, non-stationary frequency analysis of the δ18O record indicates strengthening in the 100 kyr (eccentricity) band: coincident with initial onset of Northern Hemisphere Glaciation, but ~2.4 Myr prior to strengthening in the marine record. The discrepancy between marine and high-elevation records suggests that changes in the character of the ISM may be responding to cooling in the Pacific Ocean, and may be responsible for widespread mid-Pliocene changes observed on the peripheries of the Tibetan Plateau.

  9. Performance of an irreversible quantum refrigeration cycle

    Institute of Scientific and Technical Information of China (English)

    He Ji-Zhou; Ouyang Wei-Pin; Wu Xin

    2006-01-01

    A new model of a quantum refrigeration cycle composed of two adiabatic and two isomagnetic field processes is established. The working substance in the cycle consists of many non-interacting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semi-group approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate, and power input, are given. It is found that the coefficient of performance of this cycle is in the closest analogy to that of the classical Carnot cycle. Furthermore, at high temperatures the optimal relations of the cooling rate and the maximum cooling rate are analysed in detail. Some performance characteristic curves of the cycle are plotted, such as the cooling rate versus the maximum ratio between high and low "temperatures" of the working substances, the maximum cooling rate versus the ratio between high and low "magnetic fields" and the "temperature" ratio between high and low reservoirs. The obtained results are further generalized and discussed, so that they may be directly applied to describing the performance of the quantum refrigerator using spin-J systems as the working substance. Finally, the optimum characteristics of the quantum Carnot and Ericsson refrigeration cycles are derived by analogy.

  10. [Cycling in Zagreb].

    Science.gov (United States)

    Matos, Stipan; Krapac, Ladislav; Krapac, Josip

    2007-01-01

    Cycling in Zagreb, as means of urban transport inside and outside the city, has a bright past, hazy presence but a promising future. Every day, aggressive citizens who lack urban traffic culture mistreat many cyclists but also many pedestrians. Sedentary way of living, unhealthy eating habits and inadequate recreation would surely be reduced if Zagreb had a network of cycling tracks (190 cm) or lanes (80 cm). Main city roads were constructed at the beginning of the 20th century. Today, the lack of cycling tracks is particularly evident in terms of missing connections between northern and southern parts of the city. Transportation of bikes in public vehicles, parking of bikes as well as cycling along the foot of the mountains Medvednica and Zumberacko gorje is not adequately organized. Better organization is necessary not only because of the present young generation but also because of the young who will shortly become citizens of the EU, where cycling is enormously popular. Cycling tourism is not known in Zagreb, partly due to inadequate roads. The surroundings of Zagreb are more suitable for cycling tourism and attractive brochures and tourist guides offer information to tourists on bikes. Professional, acrobatic and sports cycling do not have a tradition in Zagreb and in Croatia. The same holds true for recreational cycling and indoor exercise cycling. The authors discuss the impact of popularization of cycling using print and electronic media. The role of district and local self-government in the construction and improvement of traffic roads in Zagreb is very important. It is also significant for the implementation of legal regulations that must be obeyed by all traffic participants in order to protect cyclists, the most vulnerable group of traffic participants besides passengers. Multidisciplinary action of all benevolent experts would surely increase safety and pleasure of cycling in the city and its surroundings. This would also help reduce daily stress and

  11. Menstrual Cycle: Basic Biology

    Science.gov (United States)

    Hawkins, Shannon M.; Matzuk, Martin M.

    2010-01-01

    The basic biology of the menstrual cycle is a complex, coordinated sequence of events involving the hypothalamus, anterior pituitary, ovary, and endometrium. The menstrual cycle with all its complexities can be easily perturbed by environmental factors such as stress, extreme exercise, eating disorders, and obesity. Furthermore, genetic influences such as fragile X premutations (Chapter X), X chromosome abnormalities (Chapter X), and galactose-1-phosphate uridyltransferase (GALT) point mutations (galactosemia) also contribute to perturbations of the menstrual cycle. Although not perfect, mouse model have helped to identify and confirm additional components and pathways in menstrual cycle function and dysfunction in humans. PMID:18574203

  12. Edgeworth cycles revisited

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Joseph [MIT Sloan School of Management, 50 Memorial Drive, E52-447, Cambridge MA 02142 (United States); Muehlegger, Erich [John F. Kennedy School of Government, Harvard University, Mailbox 25, 79 JFK Street, Cambridge, MA 02138 (United States); Samphantharak, Krislert [Graduate School of International Relations and Pacific Studies, University of California at San Diego, 9500 Gilman Drive 1519, La Jolla, CA 92093 (United States)

    2010-05-15

    Some gasoline markets exhibit remarkable price cycles, where price spikes are followed by a series of small price declines: a pattern consistent with a model of Edgeworth cycles described by Maskin and Tirole. We extend the model and empirically test its predictions with a new dataset of daily station-level prices in 115 US cities. Consistent with the theory, and often in contrast with previous empirical work, we find the least and most concentrated markets are much less likely to exhibit cycling behavior both within and across cities; areas with more independent convenience-store gas stations are also more likely to cycle. (author)

  13. General Conformity

    Science.gov (United States)

    The General Conformity requirements ensure that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet national standards for air quality.

  14. General Anesthesia

    Science.gov (United States)

    ... unconscious and unable to feel pain during medical procedures. General anesthesia usually uses a combination of intravenous drugs ... 1998-2017 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.

  15. The Oxygen Cycle.

    Science.gov (United States)

    Swant, Gary D.

    Produced for primary grades, this booklet provides study of the oxygen-carbon dioxide cycle in nature. Line drawings, a minimum amount of narrative, and a glossary of terms make up its content. The booklet is designed to be used as reading material, a coloring book, or for dramatic arts with students acting out parts of the cycle. This work was…

  16. Life Cycle Environmental Management

    DEFF Research Database (Denmark)

    Pedersen, Claus Stig; Jørgensen, Jørgen; Pedersen, Morten Als

    1996-01-01

    processes. The discipline of life cycle environmental management (LCEM) focuses on the incorporation of environmental criteria from the life cycles of products and other company activities into the company management processes. This paper introduces the concept of LCEM as an important element...

  17. Nutrient cycling strategies.

    NARCIS (Netherlands)

    Breemen, van N.

    1995-01-01

    This paper briefly reviews pathways by which plants can influence the nutrient cycle, and thereby the nutrient supply of themselves and of their competitors. Higher or lower internal nutrient use efficiency positively feeds back into the nutrient cycle, and helps to increase or decrease soil

  18. Nutrient cycling strategies.

    NARCIS (Netherlands)

    Breemen, van N.

    1995-01-01

    This paper briefly reviews pathways by which plants can influence the nutrient cycle, and thereby the nutrient supply of themselves and of their competitors. Higher or lower internal nutrient use efficiency positively feeds back into the nutrient cycle, and helps to increase or decrease soil fertili

  19. Power Plant Cycling Costs

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N.; Besuner, P.; Lefton, S.; Agan, D.; Hilleman, D.

    2012-07-01

    This report provides a detailed review of the most up to date data available on power plant cycling costs. The primary objective of this report is to increase awareness of power plant cycling cost, the use of these costs in renewable integration studies and to stimulate debate between policymakers, system dispatchers, plant personnel and power utilities.

  20. Teaching the Krebs Cycle.

    Science.gov (United States)

    Akeroyd, F. Michael

    1983-01-01

    Outlines a simple but rigorous treatment of the Krebs Cycle suitable for A-level Biology students. The importance of the addition of water molecules in various stages of the cycle is stressed as well as the removal of hydrogen atoms by the oxidizing enzymes. (JN)

  1. Rock Cycle Roulette.

    Science.gov (United States)

    Schmidt, Stan M.; Palmer, Courtney

    2000-01-01

    Introduces an activity on the rock cycle. Sets 11 stages representing the transitions of an earth material in the rock cycle. Builds six-sided die for each station, and students move to the stations depending on the rolling side of the die. Evaluates students by discussing several questions in the classroom. Provides instructional information for…

  2. Teaching the Krebs Cycle.

    Science.gov (United States)

    Akeroyd, F. Michael

    1983-01-01

    Outlines a simple but rigorous treatment of the Krebs Cycle suitable for A-level Biology students. The importance of the addition of water molecules in various stages of the cycle is stressed as well as the removal of hydrogen atoms by the oxidizing enzymes. (JN)

  3. Life cycle management (LCM)

    DEFF Research Database (Denmark)

    2004-01-01

    The chapter gives an introduction to Life Cycle Management (LCM) and shows how LCM can be practiced in different contexts and at different ambition levels.......The chapter gives an introduction to Life Cycle Management (LCM) and shows how LCM can be practiced in different contexts and at different ambition levels....

  4. Stability through cycles

    NARCIS (Netherlands)

    E.A. de Groot (Bert); Ph.H.B.F. Franses (Philip Hans)

    2006-01-01

    textabstractEconomic variables like GDP growth, employment, interest rates and consumption show signs of cyclical behavior. Many variables display multiple cycles, with lengths ranging in between 5 to even up to 100 years. We argue that multiple cycles can be associated with long-run stability of th

  5. Stability through cycles

    NARCIS (Netherlands)

    Groot, de E.A. (Bert); Franses, P.H.P.H.

    2008-01-01

    Economic variables like GDP growth, employment, interest rates and consumption show signs of cyclical behavior. Many variables display multiple cycles, with periods ranging in between 5 to even up to 100 years. We argue that multiple cycles can be associated with long-run stability of the economic s

  6. Stability through cycles

    NARCIS (Netherlands)

    Groot, de E.A. (Bert); Franses, P.H.P.H.

    2006-01-01

    Economic variables like GDP growth, employment, interest rates and consumption show signs of cyclical behavior. Many variables display multiple cycles, with lengths ranging in between 5 to even up to 100 years. We argue that multiple cycles can be associated with long-run stability of the economic s

  7. HIV Life Cycle

    Science.gov (United States)

    ... Content HIV Replication Cycle Antiretroviral Drug Discovery and Development Need Help? Call 1-800-448-0440 (1 p.m. to 4 p.m. ET) Send us an email The HIV Life Cycle Last Reviewed: August 18, 2017 Key Points HIV gradually destroys the immune system by attacking and killing a type of white ...

  8. High-frequency paleobathymetry oscillations in the Campos Basin driven by orbital cycles; Oscilacoes paleobatimetricas de alta frequencia induzidas por ciclos orbitais na Bacia de Campos

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Valquiria Porfirio [Universidade Federal do Amazonas (UFAM). Inst. de Ciencias Exatas. Dept. de Geociencias (Brazil); Cunha, Armando Antonio Scarparo [Unidade de Operacoes de Exploracao e Producao da Amazonia, Exploracao, Gerencia de Sedimentologia e Estratigrafia (Brazil)], e-mail: scarparo@petrobras.com.br; Shimabukuro, Seirin [Centro de Pesquisas da Petrobras (CENPES). P e D em Geociencias, Gerencia de Bio-Estratigrafia e Paleoecologia (Brazil)], e-mail: seirin@petrobras.com.br; Gamboa, Luiz Antonio Pierantoni [Universidade Federal Fluminense (UFF), Niteroi. RJ (Brazil). Centro de Estudos Gerais. Inst. de Geociencias], e-mail: luizgamboa@gmail.com

    2010-05-15

    An integrated paleoecological, biostratigraphic and cyclostratigraphic study was carried out on sedimentary rhythm sequences in the Oligocene-Miocene of the Campos Basin, Brazil. The bio stratigraphic data combined with the spectral analysis performed on numerical data based on carbonate content variations of cores from well A, Campos Basin, reveal a periodicity related to the Milankovitch cycles. Benthic foraminiferal biofacies oscillations recognized in these cores have the same frequency and phase of long eccentricity cycles (400 Ka). Paleoceanographic changes (such as changes in ocean currents, water temperature and food supply) can modify the distribution and frequency patterns of foraminifera assemblages. However, the method used to interpret the biofacies, the geological context of the studied area and the proposed genetic model to explain the origin of these rhythmically patterned rocks, suggest that changes in foraminiferal biofacies are directly related to the paleobathymetry variations induced by glacio-eustatic oscillations of relative sea level . According to the proposed model, productivity-dilution cycles were instrumental in the origin of these marl-limestone couplets. During regressive phases, conditions were established to increase continental runoff to a bathyal setting. The increase of continental runoff with decrease of contribution of the main carbonate components led to the deposition of marlstone. During the transgressive phase, the relative reduction in clay input from continental sediments, favored a productivity growth of pelagic carbonate (calcareous nannofossil and planktonic foraminifera), which created conditions facilitating the deposition of limestone layers. The paleobathymetry oscillations, interpreted from the benthic foraminifera assemblage, and the formation of couplets, seems to be in phase with the transgressive-regressive cycles indicating a common cause to both processes. (author)

  9. The Chlamydomonas cell cycle.

    Science.gov (United States)

    Cross, Frederick R; Umen, James G

    2015-05-01

    The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important, early-diverging lineage leading to plants; and as a microbe retaining important features of the last eukaryotic common ancestor (LECA) that has been lost in the highly studied yeast lineages. Its cell biology has been studied for many decades and it has well-developed experimental genetic tools, both classical (Mendelian) and molecular. Unlike land plants, it is a haploid with very few gene duplicates, making it ideal for loss-of-function genetic studies. The Chlamydomonas cell cycle has a striking temporal and functional separation between cell growth and rapid cell division, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth and the cell division cycle; it also exhibits a highly choreographed interaction between the cell cycle and its centriole-basal body-flagellar cycle. Here, we review the current status of studies of the Chlamydomonas cell cycle. We begin with an overview of cell-cycle control in the well-studied yeast and animal systems, which has yielded a canonical, well-supported model. We discuss briefly what is known about similarities and differences in plant cell-cycle control, compared with this model. We next review the cytology and cell biology of the multiple-fission cell cycle of Chlamydomonas. Lastly, we review recent genetic approaches and insights into Chlamydomonas cell-cycle regulation that have been enabled by a new generation of genomics-based tools. © 2015 The Authors The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.

  10. Generalized polygons

    CERN Document Server

    Van Maldeghem, Hendrik

    1998-01-01

    Generalized Polygons is the first book to cover, in a coherent manner, the theory of polygons from scratch. In particular, it fills elementary gaps in the literature and gives an up-to-date account of current research in this area, including most proofs, which are often unified and streamlined in comparison to the versions generally known. Generalized Polygons will be welcomed both by the student seeking an introduction to the subject as well as the researcher who will value the work as a reference. In particular, it will be of great value for specialists working in the field of generalized polygons (which are, incidentally, the rank 2 Tits-buildings) or in fields directly related to Tits-buildings, incidence geometry and finite geometry. The approach taken in the book is of geometric nature, but algebraic results are included and proven (in a geometric way!). A noteworthy feature is that the book unifies and generalizes notions, definitions and results that exist for quadrangles, hexagons, octagons - in the ...

  11. The General Traveling Salesman Problem

    CERN Document Server

    Kleiman, Howard

    2011-01-01

    This is concerned with essentially two ways in which to construct algorithms for obtaining both approximate and exact solutions to the general traveling salesman problem (GTSP)(the triangle equality need not be satisfied). The first uses an arbitrary n-cycle to permute the columns of an n X n matrix with weighted entries. In doing so, we obtain negative entries. Using these entries, we from negative cycles. We give a formula for the length of cycles necessary to obtain an n-cycle by patching. Using patching of negative cycles, we obtain an n-cycle. The second portion of the algorithm gives procedures for obtain an exact solution to the GTSP. Our second algorithm uses the average arc-value (aav) of a path. We first obtain an n-cycle in a manner similar to that in the first algorithm. Call this T_UPPERBOUND. We then construct paths each of which has an aav less than that of T_UPPERBOUND. Using parallel programming, we construct all paths whose values are less than that of T_UPPERBOUND. Then either we obtain an ...

  12. Two Quantum Polytropic Cycles

    Science.gov (United States)

    Arias-Hernández, L. A.; Morales-Serrano, A. F.

    2002-11-01

    In this work we follow the Bender et al paper [1] to study the quantum analogues of the Stirling and Ericsson polytropic cycles. In the context of the classical thermodynamics, the Stirling and Ericsson cycles correspond to reversible heat engines with two isothermal processes joined by two polytropic branches which occur in a device called regenerator. If this device is an ideal one, the efficiency of these cycles is the Carnot efficiency. Here, we introduce the quantum analogues of the Stirling and Ericsson cycles, the first one based on a double square potential well with a finite potential barrier, since in this system the tunnel effect could be the analogue to the regeneration classical process, therefore the isochoric quantum branches would really correspond to an internal energy storage, and the last one with an unknown system where the isobaric quantum processes don't induce changes in its quantum state. With these systems the quantum engines have cycles consisting of polytropic and isothermal quantum processes analogues to the corresponding classical processes. We show that in both cases the quantum cycles have an efficiency given by ηCQM = 1 - EC/EH, which is the same expression for the quantum analogue of the Carnot cycle studied by Bender.

  13. The spatial dimension of cycle logistics

    Directory of Open Access Journals (Sweden)

    Luca Staricco

    2016-08-01

    Full Text Available Cycle logistics is emerging as a promising alternative in urban freight transport. Compared to fossil fuelled vans, the use of cycles for delivering goods within urban areas offers advantages in terms of environmental friendliness, economic efficiency, flexibility, and liveability of urban neighbourhood. At the same time, cycle logistics has to face limits in terms of weight and volume of goods that can be delivered, distances that can be covered, and spatial urban structures that can be served. This latter issue has till now received less attention in the scientific literature: it is generally recognized that cycle logistics performs at its best in inner urban areas, but no systematic study has been realized to identify specific spatial requisites for the effectiveness of cycle logistics. This paper provides a brief review of the main issues that emerge from the literature over cycle logistics, and contributes to stimulate the debate over the spatial dimension of cycle logistics: it presents a classification of cycle logistics schemes, on the basis of their integration with other urban logistic facilities and of the spatial structure of delivery operations. A three-level classification is proposed, depending on the type of goods consolidation: only distribution without consolidation, consolidation in a fixed urban consolidation centre, or consolidation in a mobile depot; for each level, operational examples and case studies are provided. This systematizing typology could support both public and private operators in decisions about the organization of cycle logistics facilities, such as the location of urban consolidation centres or the composition of cycle fleets.

  14. Generalized derivations and general relativity

    CERN Document Server

    Heller, M; Pysiak, L; Sasin, W

    2013-01-01

    We construct differential geometry (connection, curvature, etc.) based on generalized derivations of an algebra A. Such a derivation, introduced by Bresar in 1991, is given by a linear mapping u: A -> A such that there exists a usual derivation d of A satisfying the generalized Leibniz rule u(a b) = u(a) b + a d(b) for all a,b in A. The generalized geometry "is tested" in the case of the algebra of smooth functions on a manifold. We then apply this machinery to study the generalized general relativity. We define the Einstein-Hilbert action and deduce from it Einstein's field equations. We show that for a special class of metrics containing, besides the usual metric components, only one non-zero term, the action reduces to O'Hanlon action that is a Brans-Dicke action with potential and with the parameter \\omega equal to zero. We also show that the generalized Einstein equations (with zero energy-stress tensor) are equivalent to those of the Kaluza-Klein theory satisfying a "modified cylinder condition" and hav...

  15. Applied physiology of cycling.

    Science.gov (United States)

    Faria, I E

    1984-01-01

    Historically, the bicycle has evolved through the stages of a machine for efficient human transportation, a toy for children, a finely-tuned racing machine, and a tool for physical fitness development, maintenance and testing. Recently, major strides have been made in the aerodynamic design of the bicycle. These innovations have resulted in new land speed records for human powered machines. Performance in cycling is affected by a variety of factors, including aerobic and anaerobic capacity, muscular strength and endurance, and body composition. Bicycle races range from a 200m sprint to approximately 5000km. This vast range of competitive racing requires special attention to the principle of specificity of training. The physiological demands of cycling have been examined through the use of bicycle ergometers, rollers, cycling trainers, treadmill cycling, high speed photography, computer graphics, strain gauges, electromyography, wind tunnels, muscle biopsy, and body composition analysis. These techniques have been useful in providing definitive data for the development of a work/performance profile of the cyclist. Research evidence strongly suggests that when measuring the cyclist's aerobic or anaerobic capacity, a cycling protocol employing a high pedalling rpm should be used. The research bicycle should be modified to resemble a racing bicycle and the cyclist should wear cycling shoes. Prolonged cycling requires special nutritional considerations. Ingestion of carbohydrates, in solid form and carefully timed, influences performance. Caffeine appears to enhance lipid metabolism. Injuries, particularly knee problems which are prevalent among cyclists, may be avoided through the use of proper gearing and orthotics. Air pollution has been shown to impair physical performance. When pollution levels are high, training should be altered or curtailed. Effective training programmes simulate competitive conditions. Short and long interval training, blended with long

  16. GENERAL EQUILIBRIUM

    Directory of Open Access Journals (Sweden)

    Monique Florenzano

    2008-09-01

    Full Text Available General equilibrium is a central concept of economic theory. Unlike partial equilibrium analysis which study the equilibrium of a particular market under the clause “ceteris paribus” that revenues and prices on the other markets stay approximately unaffected, the ambition of a general equilibrium model is to analyze the simultaneous equilibrium in all markets of a competitive economy. Definition of the abstract model, some of its basic results and insights are presented. The important issues of uniqueness and local uniqueness of equilibrium are sketched; they are the condition for a predictive power of the theory and its ability to allow for statics comparisons. Finally, we review the main extensions of the general equilibrium model. Besides the natural extensions to infinitely many commodities and to a continuum of agents, some examples show how economic theory can accommodate the main ideas in order to study some contexts which were not thought of by the initial model

  17. 从旋回的有序叠加形式到层序的识别和划分:层序地层学进展之三%From vertical stacking pattern of cycles to discerning and division of sequences: The third advance in sequence stratigraphy

    Institute of Scientific and Technical Information of China (English)

    梅冥相

    2011-01-01

    generally form a vertical stacking pattern in the third-order sequence, and this vertically stacking pattern of meter-scale cycle becomes a main marker to study the change of sedimentary trends within the third-order sequence. Importantly, studies on sedimentary cycles that are genetically related to the Milankovitch cycles are grouped into the main content of other stratigraphic discipline, i.e. the cyclostratigraphy. Therefore, if the study on inconsistence of conceptual system for the Exxon sequence stratigraphic model represents the first ad vance, while the research on the forming mechanism of those long-term sequences is the second advance in sequence stratigraphy, the study on the discerning and division on the basis of regular vertical stacking patterns of cycles can delegate the third advance in sequence stratigraphy, which is marked by the mingling of both sequence stratigraphy and cyclostratigraphy.

  18. General Relativity

    CERN Document Server

    Canuto, V

    2015-01-01

    This is an English translation of the Italian version of an encyclopedia chapter that appeared in the Italian Encyclopedia of the Physical Sciences, edited by Bruno Bertotti (1994). Following requests from colleagues we have decided to make it available to a more general readership. We present the motivation for constructing General Relativity, provide a short discussion of tensor algebra, and follow the set up of Einstein equations. We discuss briefly the initial value problem, the linear approximation and how should non gravitational physics be described in curved spacetime.

  19. Fundamental cycles and graph embeddings

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we investigate fundamental cycles in a graph G and their relations with graph embeddings. We show that a graph G may be embedded in an orientable surface with genus at least g if and only if for any spanning tree T , there exists a sequence of fundamental cycles C1, C2, . . . , C2g with C2i-1 ∩ C2i≠ф for 1≤ i ≤g. In particular, among β(G) fundamental cycles of any spanning tree T of a graph G, there are exactly 2γM (G) cycles C1, C2, . . . , C2γM (G) such that C2i-1 ∩ C2i≠ф for 1 ≤i≤γM (G), where β(G) and γM (G) are the Betti number and the maximum genus of G, respectively. This implies that it is possible to construct an orientable embedding with large genus of a graph G from an arbitrary spanning tree T (which may have very large number of odd components in G\\E(T )). This is different from the earlier work of Xuong and Liu, where spanning trees with small odd components are needed. In fact, this makes a common generalization of Xuong, Liu and Fu et al. Furthermore, we show that (1) this result is useful for locating the maximum genus of a graph having a specific edge-cut. Some known results for embedded graphs are also concluded; (2) the maximum genus problem may be reduced to the maximum matching problem. Based on this result and the algorithm of Micali-Vazirani, we present a new efficient algorithm to determine the maximum genus of a graph in O((β(G)) 25 ) steps. Our method is straight and quite different from the algorithm of Furst, Gross and McGeoch which depends on a result of Giles where matroid parity method is needed.

  20. Comparison Between helium cycle and Supercritical CO{sub 2} Cycle for MMR and AMR

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Seong Jun; Lee, Jeong Ik; Ahn, Yoon Han; Lee, Je Kyoung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2013-05-15

    Korea Atomic Energy Research Institute (KAERI) started the development of Mobile Multi-Purpose Reactor (MMR), which is a 10MWth gas-cooled reactor. MMR is aiming for maximizing mobility, high performance, durability and safety. This is in order to use the MMR for many purposes such as ship propulsion, train engine and so on. MMR generally uses helium Brayton cycle as a power conversion system since it can obtain very simple system arrangement with direct cycle. However, some researchers have proposed that the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle can be more efficient energy converting cycle for the high temperature gas cooled reactor (HTGR) and the very high temperature reactor (VHTR) system as well. Thus, this paper is to compare helium Brayton cycle to the S-CO{sub 2} Brayton cycle in terms of the efficiency while varying turbine inlet temperature (T. I. T). A cascaded S-CO{sub 2} cycle which had been proposed by Argonne National laboratory (ANL) was used as the S-CO{sub 2} Brayton cycle configuration. This cycle is to overcome the mismatch of temperature drop between reactor coolant and CO{sub 2} through the reactor heat exchanger (RHX). Our research team reviewed the ANL research by using the in-house codes developed by the Korea Advanced institute of Science and Technology (KAIST) research team. The calculation error between the in-house code and previous result was -0.36%.

  1. A combined cycle engine test facility

    Energy Technology Data Exchange (ETDEWEB)

    Engers, R.; Cresci, D.; Tsai, C. [General Applied Science Laboratories Inc., Ronkonkoma, NY (United States)

    1995-09-01

    Rocket-Based Combined-Cycle (RBCC) engines intended for missiles and/or space launch applications incorporate features of rocket propulsion systems operating in concert with airbreathing engine cycles. Performance evaluation of these types of engines, which are intended to operate from static sea level take-off to supersonic cruise or accerlerate to orbit, requires ground test capabilities which integrate rocket component testing with airbreathing engine testing. A combined cycle engine test facility has been constructed in the General Applied Science Laboratories, Inc. (GASL) Aeropropulsion Test Laboratory to meet this requirement. The facility was designed to support the development of an innovative combined cycle engine concept which features a rocket based ramjet combustor. The test requirements included the ability to conduct tests in which the propulsive force was generated by rocket only, the ramjet only and simultaneous rocket and ramjet power (combined cycle) to evaluate combustor operation over the entire engine cycle. The test facility provides simulation over the flight Mach number range of 0 to 8 and at various trajectories. The capabilities of the combined cycle engine test facility are presented.

  2. Waste Stream Analyses for Nuclear Fuel Cycles

    Energy Technology Data Exchange (ETDEWEB)

    N. R. Soelberg

    2010-08-01

    A high-level study was performed in Fiscal Year 2009 for the U.S. Department of Energy (DOE) Office of Nuclear Energy (NE) Advanced Fuel Cycle Initiative (AFCI) to provide information for a range of nuclear fuel cycle options (Wigeland 2009). At that time, some fuel cycle options could not be adequately evaluated since they were not well defined and lacked sufficient information. As a result, five families of these fuel cycle options are being studied during Fiscal Year 2010 by the Systems Analysis Campaign for the DOE NE Fuel Cycle Research and Development (FCRD) program. The quality and completeness of data available to date for the fuel cycle options is insufficient to perform quantitative radioactive waste analyses using recommended metrics. This study has been limited thus far to qualitative analyses of waste streams from the candidate fuel cycle options, because quantitative data for wastes from the front end, fuel fabrication, reactor core structure, and used fuel for these options is generally not yet available.

  3. General Assembly

    CERN Multimedia

    Staff Association

    2016-01-01

    5th April, 2016 – Ordinary General Assembly of the Staff Association! In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Tuesday, April 5th 2016 from 11:00 to 12:00 in BE Auditorium, Meyrin (6-2-024). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its financial management, and an opportunity to express one’s opinion, including taking part in the votes. Other points are listed on the agenda, as proposed by the Staff Council. Who can vote? Only “ordinary” members (MPE) of the SA can vote. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give his/her opinion? The Ordinary General Asse...

  4. Generalized Parabolas

    Science.gov (United States)

    Joseph, Dan; Hartman, Gregory; Gibson, Caleb

    2011-01-01

    In this article we explore the consequences of modifying the common definition of a parabola by considering the locus of all points equidistant from a focus and (not necessarily linear) directrix. The resulting derived curves, which we call "generalized parabolas," are often quite beautiful and possess many interesting properties. We show that…

  5. General discussion

    NARCIS (Netherlands)

    Jagers op Akkerhuis, Gerard A.J.M.

    2016-01-01

    The general discussion focuses on some aspects that are of overarching relevance for all the preceding chapters. The fi rst subject that is discussed is the relationship between systems theory and the philosophy of science. After a short summary of the principles of system science and the

  6. Generale preventie

    NARCIS (Netherlands)

    1949-01-01

    In part I of this study a survey has veen given of what Dutch authors have written since 1870, when capital punishment was abolished, on subjects concerning the general preventive effect of punishment. This historical survey ends where, during the years 1940-1945, under the stress of the occupation

  7. Generalization and Alternatives of Kaprekar's Routine

    CERN Document Server

    Smarandache, Florentin

    2010-01-01

    We extend Kaprekar's Routine for a large class of applications. We also give particular examples of this generalization as alternatives to Kaprekar's Routine and Number. Some open questions about the length of the iterations until reaching either zero or a constant or a cycle, and about the length of the cycles are asked at the end.

  8. The Sun and climate

    Science.gov (United States)

    ,

    2000-01-01

    Many geologic records of climatic and environmental change based on various proxy variables exhibit distinct cyclicities that have been attributed to extraterrestrial forcing. The best known of these are the changes in Earth’s orbital geometry called Milankovitch Cycles, with periodicities of tens to hundreds of thousands of years. However, many cycles seem to have subMilankovitch periodicities, commonly on decadal and centennial scales, similar to those of known solar cycles. A direct connection between solar irradiance (solar constant) and weather and climate has been suggested for more than 100 years but generally rejected by most scientists, who assume that the effect of solar variations would be small. However, recent satellite radiometer measurements and modeling studies indicate that small changes in total solar irradiance could produce global temperature changes of the magnitude suggested for climatic events such as the Little Ice Age (A.D. 1550–1700).

  9. Cycles in graphs

    CERN Document Server

    Alspach, BR

    1985-01-01

    This volume deals with a variety of problems involving cycles in graphs and circuits in digraphs. Leading researchers in this area present here 3 survey papers and 42 papers containing new results. There is also a collection of unsolved problems.

  10. The Rock Cycle

    Science.gov (United States)

    Singh, Raman J.; Bushee, Jonathan

    1977-01-01

    Presents a rock cycle diagram suitable for use at the secondary or introductory college levels which separates rocks formed on and below the surface, includes organic materials, and separates products from processes. (SL)

  11. Animating the Carbon Cycle

    OpenAIRE

    2014-01-01

    Understanding the biogeochemical processes reg- ulating carbon cycling is central to mitigating atmospheric CO2 emissions. The role of living organisms has been accounted for, but the focus has traditionally been on contributions of plants and microbes. We develop the case that fully ‘‘animating’’ the carbon cycle requires broader consideration of the functional role of animals in mediating biogeochemical processes and quanti- fication of their effects on carbon storage and exchange among ter...

  12. Diurnal Cycle Computations

    Energy Technology Data Exchange (ETDEWEB)

    Covey, Curt [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Doutriaux, Charles [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-01

    Directory /export_backup/covey1/CMIP5/Precipitation/DiurnalCycle/GridpointTimeseries/CMCCBCM_etal/ on crunchy.llnl.gov contains Python / UV-CDAT scripts compositeDiurnalStatistics.py and fourierDiurB nalAllGrid.py. compositeDiurnalStatistics.py reads high-time-frequency climate data from one or more years and computes 24 hour composite-mean and composite-standard-deviation cycles for one requested month.

  13. Menstrual Cycle: Basic Biology

    OpenAIRE

    2008-01-01

    The basic biology of the menstrual cycle is a complex, coordinated sequence of events involving the hypothalamus, anterior pituitary, ovary, and endometrium. The menstrual cycle with all its complexities can be easily perturbed by environmental factors such as stress, extreme exercise, eating disorders, and obesity. Furthermore, genetic influences such as fragile X premutations (Chapter X), X chromosome abnormalities (Chapter X), and galactose-1-phosphate uridyltransferase (GALT) point mutati...

  14. Changing Credit Limits, Changing Business Cycles

    DEFF Research Database (Denmark)

    Jensen, Henrik; Ravn, Søren Hove; Santoro, Emiliano

    In the last decades, capital markets across the industrialized world have undergone massive deregulation, involving increases in the loan-to-value (LTV) ratios of households and firms. We study the business-cycle implications of this phenomenon in a dynamic general equilibrium model with multiple...... poses a serious challenge for regulatory and macroprudential policies....

  15. Quantifying the adaptive cycle

    Science.gov (United States)

    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.

  16. Solar Cycle Predictions

    Science.gov (United States)

    Pesnell, William Dean

    2012-01-01

    Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as you consume the reduced propellant load more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations how those predictions could be made more accurate in the future will be discussed.

  17. [General psychotherapy].

    Science.gov (United States)

    Vymetal, J

    2003-01-01

    Nowadays a theoretical psychotherapeutical thinking develops from the eclectic practice and uses particularly the research of the effective factors of the therapy. Best they can be characterized as differentiate, synthetic, integrative and exceeding other approaches. The development in question goes on with attempts of creating a general model of the psychotherapy that could be a basis for models of special psychotherapies. The aim of such a model is to describe all that is present as important factor for inducing a desirable change of a human in all psychotherapeutical approaches. Among general models we can mention the generic model of D. E. Orlinski and K. I. Howard, Grawe's cube (the author is K. Grawe) and the equation of the psychotherapy.

  18. Generalized polygons

    CERN Document Server

    Maldeghem, Hendrik

    1998-01-01

    This book is intended to be an introduction to the fascinating theory ofgeneralized polygons for both the graduate student and the specialized researcher in the field. It gathers together a lot of basic properties (some of which are usually referred to in research papers as belonging to folklore) and very recent and sometimes deep results. I have chosen a fairly strict geometrical approach, which requires some knowledge of basic projective geometry. Yet, it enables one to prove some typically group-theoretical results such as the determination of the automorphism groups of certain Moufang polygons. As such, some basic group-theoretical knowledge is required of the reader. The notion of a generalized polygon is a relatively recent one. But it is one of the most important concepts in incidence geometry. Generalized polygons are the building bricks of Tits buildings. They are the prototypes and precursors of more general geometries such as partial geometries, partial quadrangles, semi-partial ge­ ometries, near...

  19. The Effect of Cycling Intensity on Cycling Economy During Seated and Standing Cycling.

    Science.gov (United States)

    Arkesteijn, Marco; Jobson, Simon; Hopker, James; Passfield, Louis

    2016-10-01

    Previous research has shown that cycling in a standing position reduces cycling economy compared with seated cycling. It is unknown whether the cycling intensity moderates the reduction in cycling economy while standing. The aim was to determine whether the negative effect of standing on cycling economy would be decreased at a higher intensity. Ten cyclists cycled in 8 different conditions. Each condition was either at an intensity of 50% or 70% of maximal aerobic power at a gradient of 4% or 8% and in the seated or standing cycling position. Cycling economy and muscle activation level of 8 leg muscles were recorded. There was an interaction between cycling intensity and position for cycling economy (P = .03), the overall activation of the leg muscles (P = .02), and the activation of the lower leg muscles (P = .05). The interaction showed decreased cycling economy when standing compared with seated cycling, but the difference was reduced at higher intensity. The overall activation of the leg muscles and the lower leg muscles, respectively, increased and decreased, but the differences between standing and seated cycling were reduced at higher intensity. Cycling economy was lower during standing cycling than seated cycling, but the difference in economy diminishes when cycling intensity increases. Activation of the lower leg muscles did not explain the lower cycling economy while standing. The increased overall activation, therefore, suggests that increased activation of the upper leg muscles explains part of the lower cycling economy while standing.

  20. A Milankovitch climate control on the Middle Miocene Mediterranean Intermediate Water: evidence from benthic microfauna and isotope geochemistry of the Ras Il-Pellegrin composite section (Malta island, central Mediterranean)

    Science.gov (United States)

    Rocca, D.; Bellanca, A.; Neri, R.; Russo, B.; Sgarrella, F.; Sprovieri, M.

    2003-04-01

    interpreted as a tracer of high production of proto-MIW, during periods of high eccentricity and, probably, precession minima, characterized by coldest winter seasons. These results point out a direct link between selected benthic species, long term astronomical forcing, and deep water response and provide an useful tool for astronomical calibration of geological time and paleoceanographic reconstructions. REFERENCES Johnson D. (1985). Abyssal teleconnections II. Initation of Antarctic Bottom Water flow in the southwestern Atlantic. In: Hsű K. And Weissert H. eds. - South Atlantic paleoceanography, 283-325, Cambridge (Cambridge University Press). Laskar J., Joutel F. &Boudin F. (1993). Orbital precession and insolation quantities for the Earth form 20 Myr to +10 Myr. Astron. Astrophys., 270: 522-533, Washinghon. Sprovieri M., Caruso A., Foresi L., Bellanca A., Neri R., Mazzola S. &Sprovieri R. (2002). Astronomical calibration of the upper Langhian/lower Serravallian record of Ras Il-Pellegrin section (Malta Island, central Mediterranean). In: Iaccarino S.M. (ed.) Integrated Stratigraphy and Paleoceanography of the Mediterranean Middle Miocene. Riv. It. Paleont. Strat., 108: 183-193, Milano. Woodruff F. &Savin S.M. (1991). Mid-Miocene isotope stratigraphy in the deep-sea: high resolution correlations, paleoclimatic cycles, and sediment preservation. Palaeoceanography, 6: 755-806, Washington.

  1. Helium process cycle

    Science.gov (United States)

    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.

  2. Historicising the Hydrosocial Cycle

    Directory of Open Access Journals (Sweden)

    Jeremy J. Schmidt

    2014-02-01

    Full Text Available This paper examines the historical claims made in support of the hydrosocial cycle. In particular, it considers how arguments advancing the hydrosocial cycle make historical claims regarding modernist conceptions of what water is (i.e. H2O and its fit with society. The paper gives special emphasis to the society/nature dualism and to the notion of agency as key sites of contest in arguments regarding the hydrosocial cycle. It finds that, while several versions of the hydrosocial cycle seek to advance a political ecology more sensitive to non-human actions, these same accounts often do not address the robust account of non-human agency in the historical record. Evidence is presented regarding water’s agency amongst late 19th and early 20th century architects of key water management norms in the United States. This evidence troubles accounts of the hydrosocial cycle that critique the US experience and suggests new directions for rethinking the role of historical and institutional norms in water policy.

  3. Major Space Weather Events during the Weak Solar Cycle 24

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    We report on the level of solar activity during cycles 23 and 24 as the cycles build toward the corresponding solar maxima. The prolonged minimum period that followed solar cycle 23 and the weaker magnetic field at the poles seem to have resulted in a weaker level of activity during cycle 24. The double speak structure often observed in the maximum phases seems to be present during cycle 24, with the first peak having a sunspot number of only N90. large solar energetic particle (SEP) events, major geomagnetic storms, and radio-emitting interplanetary shocks have been observed in relatively sma:ier numbers. While the number of large SEP events during the rise phase of cycles 24 is not too different from that of cycle 23, they are generally less intense. Five ground level enhancement (GlE) events occurred up to the first activity peak in cycle 23, while a lone GlE event has been observed during the corresponding phase in cycle 24. There were 35 large (Dst S -100 nT) geomagnetic storms during the first 4.5 years of cycle 23, while only 5 occurred during cycle 24. The subdued activity during cycle 23 is consistent with the low numbers of type II radio bursts, full halo CMEs, and interplanetary shocks.

  4. Mammalian cycles: internally defined periods and interaction-driven amplitudes.

    Science.gov (United States)

    Ginzburg, L R; Krebs, C J

    2015-01-01

    The cause of mammalian cycles-the rise and fall of populations over a predictable period of time-has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles' periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016) to be of extraordinarily low amplitude.

  5. BIFURCATION OF LIMIT CYCLES FROM A DOUBLE HOMOCLINIC LOOP WITH A ROUGH SADDLE

    Institute of Scientific and Technical Information of China (English)

    HAN MAOAN; BI PING

    2004-01-01

    This paper concerns with the bifurcation of limit cycles from a double bomoclinic loop under multiple parameter perturbations for general planar systems. The existence conditions of 4 homoclinic bifurcation curves and small and large limit cycles are especially investigated.

  6. Life Cycle Sustainability Dashboard

    DEFF Research Database (Denmark)

    Traverso, Marzia; Finkbeiner, Matthias; Jørgensen, Andreas

    2012-01-01

    One method to assess the sustainability performance of products is life cycle sustainability assessment (LCSA), which assesses product performance considering the environmental,economic, and social dimensions of the life cycle. The results of LCSA can be used to compare different products...... of sustainability is the communicability of the results by means of a graphical representation (a cartogram), characterized by a suitable chromatic scale and ranking score. The integration of LCSA and the dashboard of sustainability into a so-called Life Cycle Sustainability Dashboard (LCSD) is described here...... or to support decision making toward sustainable production and consumption. In both cases, LCSA results could be too disaggregated and consequently too difficult to understand and interpret by decision makers. As non-experts are usually the target audience of experts and scientists, and are also involved...

  7. Advanced heat pump cycle

    Energy Technology Data Exchange (ETDEWEB)

    Groll, E.A.; Radermacher, R.

    1993-07-01

    The desorption and absorption process of a vapor compression heat pump with a solution circuit (VCHSC) proceeds at gliding temperature intervals, which can be adjusted over a wide range. In case that the gliding temperature intervals in the desorber and the absorber overlap, a modification of the VCHSC employing a desorber/absorber heat exchange (DAHX) can be introduced, which results in an extreme reduction of the pressure ratio. Although the DAHX-cycle has features of a two-stage cycle, it still requires only one solution pump, one separator and one compressor. Such a cycle for the working pair ammonia/water is built in the Energy Laboratory of the Center for Environmental Energy Engineering at the University of Maryland. The experimental results obtained with the research plant are discussed and compared to those calculated with a simulation program. The possible temperature lift between heat source and heat sink depending on the achievable COP are presented.

  8. Superfluid thermodynamic cycle refrigerator

    Science.gov (United States)

    Swift, Gregory W.; Kotsubo, Vincent Y.

    1992-01-01

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

  9. MILANKOVITCH CYCLES AND SEQUENCE DIVISION AND CoRRELATIoN OF THE MEMBER 4 OF THE SHAHEJIE FORMATION IN THE DoNGYING DEPRESSION,SHANDONG%东营凹陷沙河街组四段滩坝砂米氏旋回层序划分与对比

    Institute of Scientific and Technical Information of China (English)

    张海峰; 张林晔; 姚益民; 张守鹏

    2008-01-01

    东营凹陷南斜坡沙河街组四段上亚段滨浅湖滩坝相砂体分布规律复杂、预测难度大,高分辨率层序地层学因为存在高级别层序划分标准不严格的问题,难以形成统一的精细等时地层格架.借用米氏旋回地层学研究方法识别出的米氏旋回作为天然时间标尺,对该地区博15井、官9井和王94井沙四上地层进行了米氏旋回高级别层序划分与对比,所获得的高级别层序地层格架不受人为因素的影响,且能合理地解释地层的形成环境、预测有利砂体的分布规律,因而是有效且准确的.

  10. Milankovitch Cycles in the Upper Ordovician Lianglitage Formation in the Tazhong-Bachu Area, Tarim Basin%塔里木盆地塔中-巴楚地区上奥陶统良里塔格组米兰科维奇旋回性沉积记录研究

    Institute of Scientific and Technical Information of China (English)

    赵宗举; 陈轩; 潘懋; 吴兴宁; 郑兴平; 潘文庆

    2010-01-01

    通过露头、钻井岩芯沉积相观察及高频旋回识别,结合全岩碳氧同位素旋回、自然伽玛能谱测井ln(Th/K)值频谱分析及地震反射特征,研究了塔里木盆地塔中-巴楚地区分布的上奥陶统良里塔格组开阔台地及外缓坡相碳酸盐岩中发育的四~六级高频层序(旋回)特征及其叠置关系.认为其六级米级旋回、五级准层序及四级准层序组可能分别与20~40 ka、100 ka及400 ka周期的Milankovitch日-地轨道气候旋回有关,并识别出该区良里塔格组由11~12个400 ka周期的准层序组构成.提出海相碳酸盐岩全岩或生物壳碳同位素值可作为反映全球海平面相对变化的指标及识别形成三级层序的主控因素(全球海平面变化、地区性构造沉降-抬升运动)的方法--碳同位素-沉积旋回对比分析法.晚奥陶世良里塔格组沉积时期,塔中台地北缘总体表现为向上变浅的加积型沉积叠置型式,主要与塔中I号断裂活动控制形成的高陡型镶边台地边缘有关;巴楚台地西北缘则表现为向上变浅的加积-进积复合型沉积叠置型式,主要与其断裂活动弱、受沉积作用控制为主的缓坡台地边缘有关.塔中-巴楚台地良里塔格组表现为一个完整三级层序的形成与演化,主要受控于该台地的构造(沉降-抬升)运动而不是全球海平面变化,属于典型的地区性构造层序及不具有全球对比意义.

  11. Applying Frequency Spectral Analysis to Identify Milankovitch Cycle and Calculate Sedimentation Rate of Cretaceous in Wushi Sag%频谱分析法确定乌什凹陷白垩系米氏沉积旋回及沉积速率

    Institute of Scientific and Technical Information of China (English)

    郑民; 彭更新; 雷刚林; 黄少英; 吴超; 郭华清; 李曰俊

    2007-01-01

    以自然伽马曲线包含的丰富地质信息为基础,通过小波分析与快速傅里叶变换相结合,运用频谱分析法在乌什凹陷白垩系识别出米兰柯维奇沉积旋回,并确定出米氏旋回的厚度,在此基础上精确计算出资料区白垩系各层组沉积速率.其中偏心率周期引起的地层旋回厚度变化为8.70~13.89 m;地轴倾角周期引起的地层旋回厚度变化为3.01~5.88 m;岁差周期引起的地层旋回厚度变化为1.28~2.44 m.4口采样井白垩系地层平均沉积速率为0.093 78mm/a.

  12. Discussion on Milankovitch Orbit Cycle in High Frequency Sequence of Terrigenous Sequence in Fault-depressed Lacustrine Basin%断陷湖盆陆相层序中高频层序的米氏旋回成因探讨

    Institute of Scientific and Technical Information of China (English)

    胡受权; 郭文平

    2002-01-01

    以泌阳断陷湖盆下第三系核三上段为例,通过单井高频层序分析,将其划分出3个层序9个体系域,发育4类13个小层序组,其中可识别的小层序达50多个;采用滤波技术和傅里叶变换,对单井自然电位(SP)测井曲线进行技术处理,获取其沉积旋回曲线和频谱曲线,以了解优势旋回的分布及旋回时限.研究结果显示,泌阳断陷湖盆的高频层序是由米氏旋回所驱动的古气候周期性波动所形成的.亦即,古气候是影响陆相层序发育的一个重要因素,其周期性变化是源于米氏旋回的驱动力(即米兰柯维奇天文旋回).米兰柯维奇天文旋回包括偏心率旋回、倾斜率旋回和岁差旋回,这几个轨道参数所驱动的古气候变迁,分别形成了周期为10万a(或40万a)、4万a及2万a的高频层序,即小层序组、小层序及小层单元.

  13. A calculation of denudation amount on Palaeogene-Neogene unconformity in Shengtuo area of Dongying sag using Milankovitch cycle method%利用米氏旋回法计算东营凹陷胜坨地区古近-新近系不整合的剥蚀量

    Institute of Scientific and Technical Information of China (English)

    张海峰; 姚益民; 何青芳; 边雪梅

    2008-01-01

    东营凹陷古近系与新近系之间存在一区域不整合面,该不整合面抬升剥蚀过程的恢复和剥蚀量计算,对恢复区内埋藏史、热史以及生烃史有重要意义.通过对东营凹陷胜坨地区24口钻井测井资料的分析研究,利用米氏旋回地层学方法获得的地层地质年龄、沉积速率作为沉积速率剥蚀量计算方法的参数,计算出了该地区古近-新近系不整合的剥蚀量,所获得的结果与现有的地质认识吻合较好.

  14. 以米氏旋回为标尺进行高级别层序地层划分与对比——以准噶尔盆地中Ⅰ区块为例%High -resolution sequence stratigraphic classification and correlation by using Milankovitch Cycles as rulers——taking the Zhong I block in Junggar Basin as an example

    Institute of Scientific and Technical Information of China (English)

    张海峰

    2006-01-01

    准噶尔盆地中Ⅰ区块在三工河组二段沉积时期,盆大水浅,沉积旋回变化快,由于缺乏高级别层序划分的天然标准,高级别层序划分意见难以统一.依据旋回地层学研究方法识别出的米氏旋回作为层序地层划分和对比的标尺,对三工河二段四级、五级层序进行划分和对比,保证了研究区各条剖面高级别层序划分方案的统一性,提高了高分辨率层序地层格架的准确程度.研究表明,所建立的高分辨率层序地层格架与实际区域地质认识是完全吻合的.

  15. THE INFORMATION OF MILANKOVITCH ORBIT CYCLE IN HIGH FREQUENCY SEQUENCE OF THE UPPER MEMBER OF Eh3 IN BIYANG FAULT-DEPRESSION%泌阳断陷下第三系核三上段高频层序中米兰柯维奇天文旋回信息

    Institute of Scientific and Technical Information of China (English)

    胡受权; 郭文平; 邵荣松

    2000-01-01

    古气候是影响陆相层序发育的一个重要因素,其周期性变化是源于天文旋回的驱动力(即米兰柯维奇假说).米兰柯维奇天文旋回包括偏心率旋回、倾斜率旋回和岁差旋回,这几个轨道参数所驱动的古气候变迁,分别形成了周期为10万年(或40万年)、4万年及2万年的高频层序,即小层序组、小层序及小层单元.研究结果显示,泌阳断陷湖盆的高频层序是由地球轨道旋回所驱动的古气候周期性变迁所形成的.

  16. The Identification of Milankovitch Cycles in the Gray-Level Series of Fe-Mn Crust from the Central Pacific Ocean and Its Growth Rate Evolution%中太平洋铁锰结壳灰度序列中米兰柯维奇周期的识别及结壳生长速率的演化

    Institute of Scientific and Technical Information of China (English)

    韩喜球; 邱中炎

    2010-01-01

    利用数字图像处理方法提取中太平洋海山铁锰结壳(CB14)生长剖面的灰度序列,运用功率谱分析方法揭示出结壳由表及里5个亚层中分别存在多级序的显著周期,它们均能够分别与地球轨道周期(偏心率周期、黄赤交角周期和岁差周期)的级序很好匹配,根据匹配结果获得CB14第1至第5亚层的生长速率分别为2.15、2.70、2.43、2.75、2.67 mm/Ma,各亚层的界面年龄分别为1.3、2.5、5.9、6.7、7.5 Ma.表明晚中新世以来,结壳的生长速率呈现波动变化,最近1.3 Ma以来,结壳的生长速率明显减慢.认为通过识别结壳灰度序列中存在的米兰柯维奇周期可以有效获得结壳各生长阶段的高分辨率生长速率,可以为研究中新世以来古海洋环境的演化提供重要信息.

  17. Towards a methodology of psychological practice - The regulative cycle

    NARCIS (Netherlands)

    vanStrien, PJ

    1997-01-01

    This article addresses the methodology of professional practice. As a counterpart to the 'predictive cycle' of generalizing or nomological science, a regulative cycle is proposed, which is directed towards the improvement of individual problem-situations with the help of low-level, problem-directed

  18. Towards a methodology of psychological practice - The regulative cycle

    NARCIS (Netherlands)

    vanStrien, PJ

    1997-01-01

    This article addresses the methodology of professional practice. As a counterpart to the 'predictive cycle' of generalizing or nomological science, a regulative cycle is proposed, which is directed towards the improvement of individual problem-situations with the help of low-level, problem-directed

  19. Life Cycle Environmental Management

    DEFF Research Database (Denmark)

    Pedersen, Claus Stig; Jørgensen, Jørgen; Pedersen, Morten Als

    1996-01-01

    A precondition for environmentally conscious management is the awareness of the environmental impact potentials created by an industrial company. There is an obvious need for management tools to support the implementation of relevant environmental criteria into the industrial decision making...... processes. The discipline of life cycle environmental management (LCEM) focuses on the incorporation of environmental criteria from the life cycles of products and other company activities into the company management processes. This paper introduces the concept of LCEM as an important element...... of the complete set of environmental objects in an industrial manufacturing company....

  20. Revenue cycle management.

    Science.gov (United States)

    Manley, Ray; Satiani, Bhagwan

    2009-11-01

    With the widening gap between overhead expenses and reimbursement, management of the revenue cycle is a critical part of a successful vascular surgery practice. It is important to review the data on all the components of the revenue cycle: payer contracting, appointment scheduling, preregistration, registration process, coding and capturing charges, proper billing of patients and insurers, follow-up of accounts receivable, and finally using appropriate benchmarking. The industry benchmarks used should be those of peers in identical groups. Warning signs of poor performance are discussed enabling the practice to formulate a performance improvement plan.

  1. Cycles in fossil diversity

    Energy Technology Data Exchange (ETDEWEB)

    Rohde, Robert A.; Muller, Richard A.

    2004-10-20

    It is well-known that the diversity of life appears to fluctuate during the course the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 Ma). Using Sepkoski's compendium of the first and last stratigraphic appearances of 36380 marine genera, we report a strong 62 {+-} 3 Myr cycle, which is particularly strong in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance, we also consider contributing environmental factors and possible causes.

  2. General Relativity

    CERN Document Server

    Khriplovich, I. B

    2005-01-01

    This book offers an alternative to other textbooks on the subject, providing a more specific discussion of numerous general relativistic effects for readers who have knowledge of classical mechanics and electrodynamics, including special relativity. Coverage includes gravitational lensing, signal retardation in the gravitational field of the Sun, the Reissner-Nordström solution, selected spin effects, the resonance transformation of an electromagnetic wave into a gravitational one, and the entropy and temperature of black holes. The book includes numerous problems at various levels of difficulty, making it ideal also for independent study by a broad readership of advanced students and researchers. I.B. Khriplovich is Chief Researcher, Budker Institute of Nuclear Physics, Novosibirsk, and Chair of Theoretical Physics at Novosibirsk University. Dr. Khriplovich is a Corresponding Member of the Russian Academy of Sciences. He has been awarded the Dirac Medal ``For the advancement of theoretical physics'' by Univ...

  3. [General anesthesia].

    Science.gov (United States)

    Feiss, P

    2001-04-30

    General anaesthesia is a reversible loss of consciousness induced and maintained with a hypnotic drug given either by venous injection and infusion, or by inhalation. A potent opioid is usually associated to inhibit the transmission of pain and thus to lessen sympathetic and endocrine reactions to nociceptive stimuli. Myorelaxation is used to facilitate tracheal intubation and surgery. Whatever the anaesthetic protocol use, the patient and anaesthesia machine require close monitoring. In addition to vital signs, the depth of anaesthesia may be monitored using automated electroencephalographic analysis and myorelaxation should always be monitored using a nerve stimulator, but pain or analgesia evaluation is only based on clinical signs of sympathetic stimulation. Because anaesthesia-related death and morbidity have decreased considerably, future improvements in outcome should concern perioperative comfort, i.e. prevention of cognitive disturbances, nausea, vomiting and pain.

  4. Menstrual cycle pattern and fertility

    DEFF Research Database (Denmark)

    Kolstad, Henrik A.; Bonde, Jens Peter; Hjøllund, Niels Henrik;

    1999-01-01

    To characterize how the menstrual cycle pattern relates to fertility regardless of potential biases caused by inappropriate coital timing during the menstrual cycle or early embryonal loss.......To characterize how the menstrual cycle pattern relates to fertility regardless of potential biases caused by inappropriate coital timing during the menstrual cycle or early embryonal loss....

  5. Educational Business Cycles

    DEFF Research Database (Denmark)

    Tepe, Markus; Vanhuysse, Pieter

    Strong institutional constraints and better-informed voters may lead re-election seeking incumbents to shift the use of political business cycle mechanisms away from monetary and fiscal policy towards other policy domains that are more easily manipulable, targetable, and timeable. We investigate ...

  6. Educational Business Cycles

    DEFF Research Database (Denmark)

    Tepe, Markus; Vanhuysse, Pieter

    2009-01-01

    Strong institutional constraints and better-informed voters may lead re-election seeking incumbents to shift the use of political business cycle mechanisms away from monetary and fiscal policy towards other policy domains that are more easily manipulable, targetable, and timeable. We investigate ...

  7. Big Data and Cycling

    NARCIS (Netherlands)

    Romanillos, Gustavo; Zaltz Austwick, Martin; Ettema, Dick; De Kruijf, Joost

    2016-01-01

    Big Data has begun to create significant impacts in urban and transport planning. This paper covers the explosion in data-driven research on cycling, most of which has occurred in the last ten years. We review the techniques, objectives and findings of a growing number of studies we have classified

  8. Skills, sunspots and cycles

    DEFF Research Database (Denmark)

    Busato, Francesco; Marchetti, Enrico

    This paper explores the ability of a class of one-sector,multi-input models to generate indeterminate equilibrium paths, andendogenous cycles, without relying on factors' hoarding. The modelpresents a novel theoretical economic mechanism that supportssunspot-driven expansions without requiring up...

  9. 90-Day Cycle Handbook

    Science.gov (United States)

    Park, Sandra; Takahashi, Sola

    2013-01-01

    90-Day Cycles are a disciplined and structured form of inquiry designed to produce and test knowledge syntheses, prototyped processes, or products in support of improvement work. With any type of activity, organizations inevitably encounter roadblocks to improving performance and outcomes. These barriers might include intractable problems at…

  10. Marine nitrogen cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    ://www.eoearth.org/article/Marine_nitrogen_cycle equatorial Pacific and the Southern Ocean where low concentration of a micronutrient (iron) appears to limit photosynthesis. In areas characterized by low dissolved inorganic nitrogen (DIN) concentration in surface waters, dissolved organic nitrogen (DON...

  11. The Pneumocystis life cycle

    Directory of Open Access Journals (Sweden)

    Cécile-Marie Aliouat-Denis

    2009-05-01

    Full Text Available First recognised as "schizonts" of Trypanosoma cruzi, Pneumocystis organisms are now considered as part of an early-diverging lineage of Ascomycetes. As no robust long-term culture model is available, most data on the Pneumocystis cell cycle have stemmed from ultrastructural images of infected mammalian lungs. Although most fungi developing in animals do not complete a sexual cycle in vivo, Pneumocystis species constitute one of a few exceptions. Recently, the molecular identification of several key players in the fungal mating pathway has provided further evidence for the existence of conjugation and meiosis in Pneumocystisorganisms. Dynamic follow-up of stage-to-stage transition as well as studies of stage-specific proteins and/or genes would provide a better understanding of the still hypothetical Pneumocystislife cycle. Although difficult to achieve, stage purification seems a reasonable way forward in the absence of efficient culture systems. This mini-review provides a comprehensive overview of the historical milestones leading to the current knowledge available on the Pneumocystis life cycle.

  12. Re-Cycling

    Science.gov (United States)

    Brown, Robert W.; Covault, Corbin E.

    2015-01-01

    An old comedy routine on Saturday Night Live by Father Guido Sarducci introduced a "Five-Minute University," because five minutes is all that's remembered after graduation anyway. In counterpoint, we discuss "cycling," a teaching method for memory enhancement. Our principal implementation consists of offering a simple version…

  13. Assisted Cycling Tours

    Science.gov (United States)

    Hollingsworth, Jan Carter

    2008-01-01

    This article discusses Assisted Cycling Tours (ACT), a Westminster, Colorado based 501(c)3, non-profit that is offering the joy of bicycle tours in breathtaking, scenic locations to children and adults with developmental and physical disabilities and their families. ACT was founded by Bob Matter and his son David with a goal of opening up the…

  14. The Science of Cycling

    Science.gov (United States)

    Crompton, Zoe; Daniels, Shelley

    2014-01-01

    Children are engaged by finding out about science in the real world (Harlen, 2010). Many children will be cyclists or will have seen or heard about the success of British cyclists in the Olympics and the Tour de France. This makes cycling a good hook to draw children into learning science. It is also a good cross-curricular topic, with strong…

  15. Educational Business Cycles

    DEFF Research Database (Denmark)

    Tepe, Markus; Vanhuysse, Pieter

    Strong institutional constraints and better-informed voters may lead re-election seeking incumbents to shift the use of political business cycle mechanisms away from monetary and fiscal policy towards other policy domains that are more easily manipulable, targetable, and timeable. We investigate...

  16. MERCURY CYCLING AND BIOMAGNIFICATION

    Science.gov (United States)

    Mercury cycling and biomagnification was studied in man-made ponds designed for watering livestock on the Cheyenne River Sioux Reservation in South Dakota. Multiple Hg species were quantified through multiple seasons for 2 years in total atmospheric deposition samples, surface wa...

  17. Stellar magnetic cycles

    Science.gov (United States)

    Baliunas, S. L.

    2004-05-01

    Is hope for understanding the solar magnetic cycle to be found in stars? Observations of stars with significant sub-surface convective zones -- masses smaller than about 1.5 solar masses on the lower main sequence and many types of cool, post-main-sequence stars -- indicate the presence of surface and atmospheric inhomogeneities analogous to solar magnetic features, making stellar magnetic activity a cosmically widespread phenomenon. Observations have been made primarily in visible wavelengths, and important information has also been derived from the ultraviolet and x-ray spectrum regions. Interannual to interdecadal variability of spectrum indicators of stellar magnetic features is common, and in some cases similar in appearance to the 11-year sunspot cycle. Successful models of the physical processes responsible for stellar magnetic cycles, typically cast as a magnetohydrodynamic dynamo, require advances in understanding not only convection but also the magnetic field's interaction with it. The observed facts that underpin the hope for models will be summarized. Properties of stellar magnetic cycles will be compared and contrasted with those of the sun, including inferences from paleo-environmental reservoirs that contain information on solar century- to millennial-scale magnetic variability. Partial support of this research came from NASA NAG5-7635, NRC COBASE, CRDF 322, MIT-MSG 5710001241, JPL 1236821, AF 49620-02-1-0194, Richard Lounsberry Foundation, Langley-Abbot, Rollins, Scholarly Studies and James Arthur Funds (Smithsonian Institution) and several generous individuals.

  18. LIFE-CYCLE ASSESSMENT

    Science.gov (United States)

    Life Cycle Assessment, or LCA, is an environmental accounting and mangement approach that consider all the aspects of resource use and environmental releases associated with an industrial system from cradle-to-grave. Specifically, it is a holistic view of environmental interacti...

  19. Life Cycle Collection Management

    Directory of Open Access Journals (Sweden)

    Helen Shenton

    2003-09-01

    Full Text Available Life cycle collection management is a way of taking a long-term approach to the responsible stewardship of the British Library's collections and is one of the Library's strategic strands. It defines the different stages in a collection item's existence over time. These stages range from selection and acquisitions processing, cataloguing and press marking, through to preventive conservation, storage and retrieval. Life cycle collection management seeks to identify the costs of each stage in order to show the economic interdependencies between the phases over time. It thereby aims to demonstrate the long-term consequences of what the library takes into its collections, by making explicit the financial and other implications of decisions made at the beginning of the life cycle for the next 100 plus years. This paper describes the work over the past year at the British Library on this complex and complicated subject. It presents the emerging findings and suggests how it can be used for practical reasons (by individual curators and selectors and for economic, governance and political purposes. The paper describes the next steps in the project, for example, on a predictive data model. The British Library is seeking to benchmark itself against comparable organisations in this area. It intends to work with others on specific comparison for example, of life cycle costing of electronic and paper journals, as a prelude to eliding digital and 'traditional' formats.

  20. Mosquito Life Cycle

    Science.gov (United States)

    Knowing the stages of the mosquito's life will help you prevent mosquitoes around your home and help you choose the right pesticides for your needs, if you decide to use them. All mosquito species go through four distinct stages during their live cycle.

  1. The Geologic Nitrogen Cycle

    Science.gov (United States)

    Johnson, B. W.; Goldblatt, C.

    2013-12-01

    N2 is the dominant gas in Earth's atmosphere, and has been so through the majority of the planet's history. Originally thought to only be cycled in significant amounts through the biosphere, it is becoming increasingly clear that a large degree of geologic cycling can occur as well. N is present in crustal rocks at 10s to 100s of ppm and in the mantle at 1s to perhaps 10s of ppm. In light of new data, we present an Earth-system perspective of the modern N cycle, an updated N budget for the silicate Earth, and venture to explain the evolution of the N cycle over time. In an fashion similar to C, N has a fast, biologically mediated cycle and a slower cycle driven by plate tectonics. Bacteria fix N2 from the atmosphere into bioavailable forms. N is then cycled through the food chain, either by direct consumption of N-fixing bacteria, as NH4+ (the primary waste form), or NO3- (the most common inorganic species in the modern ocean). Some organic material settles as sediment on the ocean floor. In anoxic sediments, NH4+ dominates; due to similar ionic radii, it can readily substitute for K+ in mineral lattices, both in sedimentary rocks and in oceanic lithosphere. Once it enters a subduction zone, N may either be volatilized and returned to the atmosphere at arc volcanoes as N2 or N2O, sequestered into intrusive igneous rocks (as NH4+?), or subducted deep into the mantle, likely as NH4+. Mounting evidence indicates that a significant amount of N may be sequestered into the solid Earth, where it may remain for long periods (100s m.y.) before being returned to the atmosphere/biosphere by volcanism or weathering. The magnitude fluxes into the solid Earth and size of geologic N reservoirs are poorly constrained. The size of the N reservoirs contained in the solid Earth directly affects the evolution of Earth's atmosphere. It is possible that N now sequestered in the solid Earth was once in the atmosphere, which would have resulted in a higher atmospheric pressure, and

  2. The global water cycle

    Science.gov (United States)

    Oki, Taikan; Entekhabi, Dara; Harrold, Timothy Ives

    The global water cycle consists of the oceans, water in the atmosphere, and water in the landscape. The cycle is closed by the fluxes between these reservoirs. Although the amounts of water in the atmosphere and river channels are relatively small, the fluxes are high, and this water plays a critical role in society, which is dependent on water as a renewable resource. On a global scale, the meridional component of river runoff is shown to be about 10% of the corresponding atmospheric and oceanic meridional fluxes. Artificial storages and water withdrawals for irrigation have significant impacts on river runoff and hence on the overall global water cycle. Fully coupled atmosphere-land-river-ocean models of the world's climate are essential to assess the future water resources and scarcities in relation to climate change. An assessment of future water scarcity suggests that water shortages will worsen, with a very significant increase in water stress in Africa. The impact of population growth on water stress is shown to be higher than that of climate change. The virtual water trade, which should be taken into account when discussing the global water cycle and water scarcity, is also considered. The movement of virtual water from North America, Oceania, and Europe to the Middle East, North West Africa, and East Asia represents significant global savings of water. The anticipated world water crisis widens the opportunities for the study of the global water cycle to contribute to the development of sustainability within society and to the solution of practical social problems.

  3. Does an irreversible chemical cycle support equilibrium?

    CERN Document Server

    Banerjee, Kinshuk

    2013-01-01

    The impossibility of attaining equilibrium for cyclic chemical reaction networks with irreversible steps is apparently due to a divergent entropy production rate. A deeper reason seems to be the violation of the detailed balance condition. In this work, we discuss how the standard theoretical framework can be adapted to include irreversible cycles, avoiding the divergence. With properly redefined force terms, such systems are also seen to reach and sustain equilibria that are characterized by the vanishing of the entropy production rate, though detailed balance is not maintained. Equivalence of the present formulation with Onsager's original prescription is established for both reversible and irreversible cycles, with a few adjustments in the latter case. Further justification of the attainment of true equilibrium is provided with the help of the minimum entropy production principle. All the results are generalized for an irreversible cycle comprising of N number of species.

  4. Life Cycle assessment of basic chemicals

    DEFF Research Database (Denmark)

    Olsen, Stig Irving

    The present report results as part of a ph.d. project aiming at developing general rules for LCA of basic chemicals. Part 1 reviews the state of the art framework for life-cycle assessment and part 2 relates that framework to the chemical industry and gives some proposals for LCAs of basic...... chemicals. A survey of the use of LCA in the European chemical industry has been conducted and is reported in appendix 1. Life cycle assessment (LCA) is a tool/process to evaluate the potential environmental impacts of a system (most often a product) through its whole life cycle by collecting input...... and output data (together interventions) from all unit processes in the system and assessing the potential environmental impact of these interventions. The LCA framework comprise four phases which are iteratively interlinked: · Goal and scope definition · Inventory · Impact assessment · Interpretation...

  5. Properties and Surprises of Solar Activity XXIII Cycle

    Science.gov (United States)

    Ishkov, V. N.

    2010-12-01

    The main properties of the 23rd cycle match almost completely those of average-magnitude solar cycles, and some of the features of the cycle may indicate a change in the generation mode of magnetic fields in the solar convection zone. If this is the case, the Sun enters a period of intermediate and weak cycles of solar activity (SA) in terms of the Wolf number, which may last for 3 to 6 solar cycles. The main development stages of solar cycle 23 are the following: minimum of solar cycle 22: April 1996 (W* = 8.0); maximum of the smoothed relative sunspot number: April 2000; global polarity reversal of the general solar magnetic field: July to December 2000; secondary maximum of the relative sunspot number: November 2001; maximum of the 10.7-cm radio flux: February 2002; phase of the cycle maximum: October 1999 to June 2002; beginning of the decrease phase: July 2002; the point of minimum of the current SA cycle: December 2008. Solar cycle 23 has presented two powerful flare-active sunspot groups, in September 2005 and December 2006 (+5.5 and +6.6 years from the maximum) which by flare potential occupy 4th and 20th place among the most flare-active regions for the last four solar cycles. The unprecedented duration of the relative sunspot numbers fall that has led to already record duration of the last solar cycle among authentic cycles (since 1849) became the next surprise of development of solar activity during the last cycle. The phase of the minimum began in May 2005 and lasted for 4.5 years. Thus, the new solar cycle 24 has begun in January 2009.

  6. Hilbert's Sixteenth Problem and Its Generalization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper deals with Hilbert's 16th problem and its generalizations. The configurations of all closed branches of an algebraic curve of degree n are discussed. The maximum number of sheets for an algebraic equation of degree n and the maximum number of limit cycles for a planar algebraic autonomous system are achieved. The author also considers different generalizations and some related problems.

  7. The generalized Hodge and Bloch conjectures are equivalent for general complete intersections

    CERN Document Server

    Voisin, Claire

    2011-01-01

    Let $X$ be a smooth complex projective variety with trivial Chow groups. (By trivial, we mean that the cycle class is injective.) We show (assuming the Lefschetz standard conjecture) that if the vanishing cohomology of a general complete intersection $Y$ of ample hypersurfaces in $X$ has geometric coniveau $\\geq c$, then the Chow groups of cycles of dimension $\\leq c-1$ of $Y$ are trivial. The generalized Bloch conjecture for $Y$ is this statement with "geometric coniveau" replaced by "Hodge coniveau".

  8. Solar spectral irradiance changes during cycle 24

    Energy Technology Data Exchange (ETDEWEB)

    Marchenko, S. V.; DeLand, M. T. [Also at NASA/Goddard Space Flight Center, Greenbelt, MD, USA. (United States)

    2014-07-10

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by ∼0.6% ± 0.2% around 265 nm. These changes gradually diminish to 0.15% ± 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar 'continuum'. Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar 'continuum', the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at λ ≳ 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  9. Archaea in biogeochemical cycles.

    Science.gov (United States)

    Offre, Pierre; Spang, Anja; Schleper, Christa

    2013-01-01

    Archaea constitute a considerable fraction of the microbial biomass on Earth. Like Bacteria they have evolved a variety of energy metabolisms using organic and/or inorganic electron donors and acceptors, and many of them are able to fix carbon from inorganic sources. Archaea thus play crucial roles in the Earth's global geochemical cycles and influence greenhouse gas emissions. Methanogenesis and anaerobic methane oxidation are important steps in the carbon cycle; both are performed exclusively by anaerobic archaea. Oxidation of ammonia to nitrite is performed by Thaumarchaeota. They represent the only archaeal group that resides in large numbers in the global aerobic terrestrial and marine environments on Earth. Sulfur-dependent archaea are confined mostly to hot environments, but metal leaching by acidophiles and reduction of sulfate by anaerobic, nonthermophilic methane oxidizers have a potential impact on the environment. The metabolisms of a large number of archaea, in particular those dominating the subsurface, remain to be explored.

  10. Gap Cycling for SWIFT

    CERN Document Server

    Corum, Curtis A; Snyder, Carl J; Garwood, Michael

    2013-01-01

    Purpose: SWIFT (SWeep Imaging with Fourier Transformation) is a non- Cartesian MRI method with unique features and capabilities. In SWIFT, radiofrequency (RF) excitation and reception are performed nearly simultaneously, by rapidly switching between transmit and receive during a frequency-swept RF pulse. Because both the transmitted pulse and data acquisition are simultaneously amplitude-modulated in SWIFT (in contrast to continuous RF excitation and uninterrupted data acquisition in more familiar MRI sequences), crosstalk between different frequency bands occurs in the data. This crosstalk leads to a "bulls-eye" artifact in SWIFT images. We present a method to cancel this inter-band crosstalk by cycling the pulse and receive gap positions relative to the un-gapped pulse shape. We call this strategy "gap cycling." Methods: We carry out theoretical analysis, simulation and experiments to characterize the signal chain, resulting artifacts, and their elimination for SWIFT. Results: Theoretical analysis reveals t...

  11. Cycling and erectile dysfunction

    Directory of Open Access Journals (Sweden)

    Ina Šibli

    2015-01-01

    Full Text Available Abstract: For many years medical studies have implicated bicycle riding is causing erectile dysfunction (ED in association with higher perineal pressure. This review focuses upon epidemiological studies assesing the impact of cycling on ED, pathogenesis of ED in cyclists  as well as on research considering changes of perineal pressure, hemodynamics, and nerve conduction when cycling. Investigestors were also interested in different saddle sizes, materials and geometry and also in the impact of saddle and riders position on changes to the perineum. Research on female cyclists is very limited but indicates similar genitourinary disorders as in male cyclists. We also review  research on preventative and therapeutic options regarding bicycle riding and ED.

  12. FUZZY REASONING IN CYCLES

    Institute of Scientific and Technical Information of China (English)

    曹立明

    1990-01-01

    By the similarity between the syllogism in logic and a path proposition in graph theory,a new concept,fuzzy reasoning graph G has been given in this paper. Transitive closure has been studied and used to do reasoning related to self-loop in G,and an algorithm has been designed to cope with reasoning in other cycles in G. Both approaches are applicable and efficient.

  13. Forests and water cycle

    Directory of Open Access Journals (Sweden)

    Iovino F

    2009-06-01

    Full Text Available Based on a comprehensive literature analysis, a review on factors that control water cycle and water use in Mediterranean forest ecosystems is presented, including environmental variables and silvicultural treatments. This important issue is considered in the perspective of sustainable forest management of Mediterranean forests, with special regard to crucial environmental hazards such as forest fires and desertification risks related to climate change.

  14. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  15. Sen cycles and externalities

    OpenAIRE

    Piggins, Ashley; Salerno, Gillian

    2016-01-01

    It has long been understood that externalities of some kind are responsible for Sen’s (1970) theorem on the impossibility of a Paretian liberal. However, Saari and Petron (2006) show that for any social preference cycle generated by combining the weak Pareto principle and individual decisiveness, every decisive individual must suffer at least one strong negative externality. We show that this fundamental result only holds when individual preferences are strict. Building on their contribution,...

  16. The carbon dioxide cycle

    Science.gov (United States)

    James, P.B.; Hansen, G.B.; Titus, T.N.

    2005-01-01

    The seasonal CO2 cycle on Mars refers to the exchange of carbon dioxide between dry ice in the seasonal polar caps and gaseous carbon dioxide in the atmosphere. This review focuses on breakthroughs in understanding the process involving seasonal carbon dioxide phase changes that have occurred as a result of observations by Mars Global Surveyor. ?? 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

  17. Stirling cycle engine

    Science.gov (United States)

    Lundholm, Gunnar

    1983-01-01

    In a Stirling cycle engine having a plurality of working gas charges separated by pistons reciprocating in cylinders, the total gas content is minimized and the mean pressure equalization among the serial cylinders is improved by using two piston rings axially spaced at least as much as the piston stroke and by providing a duct in the cylinder wall opening in the space between the two piston rings and leading to a source of minimum or maximum working gas pressure.

  18. International Business Cycle

    Directory of Open Access Journals (Sweden)

    Marek Lubiński

    2007-04-01

    Full Text Available Prime stylized facts of international business cycle theory refer to positive correlation in the cyclical components of important macroeconomic variables across countries. However a number of indicators of business cycle synchronization do not point to clear trends. It can be ascribed to the fact that different forces influence level of business cycle correlation. When investigating into the forces behind the commonness in aggregate fluctuations economic research seems to have pointed in two directions. One strand of the literature examines the idea of common exogenous shocks that affect economies simultaneously. In addition to that economic interdependencies such as trade in goods and services or capital account transactions may serve as the channels through which disturbances spill over across countries.The observed degree of output co movement reflects both the nature of the shocks that have occurred and the degree of economic interdependence. In the periods when common shocks prevail level of synchronization is usually higher than in times of transmission dominance.

  19. A Generalization of Generalized Fibonacci and Generalized Pell Numbers

    Science.gov (United States)

    Abd-Elhameed, W. M.; Zeyada, N. A.

    2017-01-01

    This paper is concerned with developing a new class of generalized numbers. The main advantage of this class is that it generalizes the two classes of generalized Fibonacci numbers and generalized Pell numbers. Some new identities involving these generalized numbers are obtained. In addition, the two well-known identities of Sury and Marques which…

  20. Tectonometamorphic Cycles in Different Geodynamic Conditions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Formation and attenuation of crust thermal anomalies, accompanied by development of geological structures, are governed by special laws, together with metamorphism and other endogenic process, form tectonometamorphic cycle (TMC). Because of rock rheology under metamorphic conditions, the structures, concurring with metamorphism, reflect geodynamic conditions much more perfect than those of the structures of nonmetamorphosed rocks. For this reason, structural investigations open wide, sometimes unique, possibilities for geodynamic research into regional metamorphosed terrains. The TMC features under different geodynamic conditions are shown with examples of California (subduction), Himalaya and Junggar Alatau (collision), and Northwest environs of the White Sea (polycyclic development). The analysis of these units serves as basis of some general conclusions. TMC, the steady pattern of crust thermal anomalies manifestation, does not practically depend on peculiarities of metamorphism. At lower and middle crust levels, occur the high-temperature complete cycles that include following two stages. The first is represented by nappes and paragenes of parallel bedding flow, the second, by linear folds, domes and faults. At top levels of fold complexes display the low-temperature reduced cycles, expressed only by structures of the second stage. There are gradual transitions between the complete and reduced cycles. Thermal anomalies in the first stage of complete cycles devolop against the background of large horizontal displacements at contacts between interacting plates or are genetically connected with their gently sloping fault planes. Of all structural elements of the cycles, in compressional environments (nappes, linear folds, domes etc. ), only the structures of the first stage of complete cycles can be considered as indications of plate tectonics. Presence of such structures at the most ancient supracrustal complexes point to existence of plate tectonics already at

  1. Nuclear Fuel Cycle Evaluation and Real Options

    Directory of Open Access Journals (Sweden)

    L. Havlíček

    2008-01-01

    Full Text Available The first part of this paper describes the nuclear fuel cycle. It is divided into three parts. The first part, called Front-End, covers all activities connected with fuel procurement and fabrication. The middle part of the cycle includes fuel reload design activities and the operation of the fuel in the reactor. Back-End comprises all activities ensuring safe separation of spent fuel and radioactive waste from the environment. The individual stages of the fuel cycle are strongly interrelated. Overall economic optimization is very difficult. Generally, NPV is used for an economic evaluation in the nuclear fuel cycle. However the high volatility of uranium prices in the Front-End, and the large uncertainty of both economic and technical parameters in the Back-End, make the use of NPV difficult. The real option method is able to evaluate the value added by flexibility of decision making by a company under conditions of uncertainty. The possibility of applying this method to the nuclear fuel cycle evaluation is studied. 

  2. Hochschild homology, global dimension, and truncated oriented cycles

    CERN Document Server

    Han, Yang

    2010-01-01

    It is shown that a bounded quiver algebra having a 2-truncated oriented cycle is of infinite Hochschild homology dimension and global dimension, which generalizes a result of Solotar and Vigu\\'{e}-Poirrier to nonlocal ungraded algebras having a 2-truncated oriented cycle of arbitrary length. Therefore, a bounded quiver algebra of finite global dimension has no 2-truncated oriented cycles. Note that the well-known "no loops conjecture", which has been proved to be true already, says that a bounded quiver algebra of finite global dimension has no loops, i.e., truncated oriented cycles of length 1. Moreover, it is shown that a monomial algebra having a truncated oriented cycle is of infinite Hochschild homology dimension and global dimension. Consequently, a monomial algebra of finite global dimension has no truncated oriented cycles.

  3. Regenerative characteristics of magnetic or gas Stirling refrigeration cycle

    Science.gov (United States)

    Chen, J.; Yan, Z.

    A general criterion to distinguish whether a Stirling refrigeration cycle possesses the condition of perfect regeneration is given. It is proven using the criterion that a Stirling refrigeration cycle using a simple paramagnetic or ferromagnetic material as the working substance possesses the condition of perfect regeneration, as does a Stirling refrigeration cycle using an ideal or van der Waals gas as the working substance. However, a Stirling refrigeration cycle using a gas which is described by the Redlich-Kwong, Beattie-Bridgeman, Benedict-Webb-Rubin, Dieterici, Berthelot, or Martin-Hou equation as the working substance does not possess the condition of perfect regeneration and its coefficient of performance is always smaller than that of the Carnot refrigeration cycle for the same temperature range. Moreover, the effect of non-perfect regeneration on the level of refrigeration and the coefficient of performance of a Stirling refrigeration cycle is expounded using a strict equation of state.

  4. Weekly Cycle of Lightning: Evidence of Storm Invigoration by Pollution

    Science.gov (United States)

    Bell, Thomas L.; Rosenfeld, Daniel; Kim, Kyu-Myong

    2009-01-01

    We have examined summertime 1998 2009 U.S. lightning data from the National Lightning Detection Network (NLDN) to look for weekly cycles in lightning activity. As was found by Bell et al. (2008) for rain over the southeast U.S., there is a significant weekly cycle in afternoon lightning activity that peaks in the middle of the week there. The weekly cycle appears to be reduced over population centers. Lightning activity peaks on weekends over waters near the SE U.S. The statistical significance of weekly cycles over the western half of the country is generally small. We found no evidence of a weekly cycle of synoptic-scale forcing that might explain these patterns. The lightning behavior is entirely consistent with the explanation suggested by Bell et al. (2008) for the cycles in rainfall and other atmospheric data from the SE U.S., that aerosols can cause storms to intensify in humid, convectively unstable environments.

  5. Terrestrial Carbon Cycle Variability

    Science.gov (United States)

    Baldocchi, Dennis; Ryu, Youngryel; Keenan, Trevor

    2016-01-01

    A growing literature is reporting on how the terrestrial carbon cycle is experiencing year-to-year variability because of climate anomalies and trends caused by global change. As CO 2 concentration records in the atmosphere exceed 50 years and as satellite records reach over 30 years in length, we are becoming better able to address carbon cycle variability and trends. Here we review how variable the carbon cycle is, how large the trends in its gross and net fluxes are, and how well the signal can be separated from noise. We explore mechanisms that explain year-to-year variability and trends by deconstructing the global carbon budget. The CO 2 concentration record is detecting a significant increase in the seasonal amplitude between 1958 and now. Inferential methods provide a variety of explanations for this result, but a conclusive attribution remains elusive. Scientists have reported that this trend is a consequence of the greening of the biosphere, stronger northern latitude photosynthesis, more photosynthesis by semi-arid ecosystems, agriculture and the green revolution, tropical temperature anomalies, or increased winter respiration. At the global scale, variability in the terrestrial carbon cycle can be due to changes in constituent fluxes, gross primary productivity, plant respiration and heterotrophic (microbial) respiration, and losses due to fire, land use change, soil erosion, or harvesting. It remains controversial whether or not there is a significant trend in global primary productivity (due to rising CO 2, temperature, nitrogen deposition, changing land use, and preponderance of wet and dry regions). The degree to which year-to-year variability in temperature and precipitation anomalies affect global primary productivity also remains uncertain. For perspective, interannual variability in global gross primary productivity is relatively small (on the order of 2 Pg-C y -1) with respect to a large and uncertain background (123 +/- 4 Pg-C y -1), and

  6. Hybrid Combined Cycles with Biomass and Waste Fired Bottoming Cycle - a Literature Study

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Miroslav P.

    2002-02-01

    Biomass is one of the main natural resources in Sweden. The present low-CO{sub 2} emission characteristics of the Swedish electricity production system (hydro and nuclear) can be retained only by expansion of biofuel applications for energy purposes. Domestic Swedish biomass resources are vast and renewable, but not infinite. They must be utilized as efficiently as possible, in order to make sure that they meet the conditions for sustainability in the future. Application of efficient power generation cycles at low costs is essential for meeting this challenge. This applies also to municipal solid waste incineration with energy extraction, which should be preferred to its dumping in landfills. Hybrid dual-fuel combined cycle units are a simple and affordable way to increase the electric efficiency of biofuel energy utilization, without big investments, uncertainties or loss of reliability arising from complicated technologies. Configurations of such power cycles are very flexible and reliable. Their potential for high electric efficiency in condensing mode, high total efficiency in combined heat and power mode and unrivalled load flexibility is explored in this project. The present report is a literature study that concentrates on certain biomass utilization technologies, in particular the design and performance of hybrid combined cycle power units of various configurations, with gas turbines and internal combustion engines as topping cycles. An overview of published literature and general development trends on the relevant topic is presented. The study is extended to encompass a short overview of biomass utilization as an energy source (focusing on Sweden), history of combined cycles development with reference especially to combined cycles with supplementary firing and coal-fired hybrid combined cycles, repowering of old steam units into hybrid ones and combined cycles for internal combustion engines. The hybrid combined cycle concept for municipal solid waste

  7. A reverse KREBS cycle in photosynthesis: consensus at last

    Science.gov (United States)

    Buchanan, B. B.; Arnon, D. I.

    1990-01-01

    The Krebs cycle (citric acid or tricarboxylic acid cycle), the final common pathway in aerobic metabolism for the oxidation of carbohydrates, fatty acids and amino acids, is known to be irreversible. It liberates CO2 and generates NADH whose aerobic oxidation yields ATP but it does not operate in reverse as a biosynthetic pathway for CO2 assimilation. In 1966, our laboratory described a cyclic pathway for CO2 assimilation (Evans, Buchanan and Arnon 1966) that was unusual in two respects: (i) it provided the first instance of an obligate photoautotroph that assimilated CO2 by a pathway different from Calvin's reductive pentose phosphate cycle (Calvin 1962) and (ii) in its overall effect the new cycle was a reversal of the Krebs cycle. Named the 'reductive carboxylic acid cycle' (sometimes also called the reductive tricarboxylic acid cycle) the new cycle appeared to be the sole CO2 assimilation pathway in Chlorobium thiosulfatophilum (Evans et al. 1966) (now known as Chlorobium limicola forma thiosulfatophilum). Chlorobium is a photosynthetic green sulfur bacterium that grows anaerobically in an inorganic medium with sulfide and thiosulfate as electron donors and CO2 as an obligatory carbon source. In the ensuing years, the new cycle was viewed with skepticism. Not only was it in conflict with the prevailing doctrine that the 'one important property ... shared by all (our emphasis) autotrophic species is the assimilation of CO2 via the Calvin cycle' (McFadden 1973) but also some of its experimental underpinnings were challenged. It is only now that in the words of one of its early skeptics (Tabita 1988) 'a long and tortuous controversy' has ended with general acceptance of the reductive carboxylic acid cycle as a photosynthetic CO2 assimilation pathway distinct from the pentose cycle. (Henceforth, to minimize repetitiveness, the reductive pentose phosphate cycle will often be referred to as the pentose cycle and the reductive carboxylic acid cycle as the carboxylic

  8. A reverse KREBS cycle in photosynthesis: consensus at last

    Science.gov (United States)

    Buchanan, B. B.; Arnon, D. I.

    1990-01-01

    The Krebs cycle (citric acid or tricarboxylic acid cycle), the final common pathway in aerobic metabolism for the oxidation of carbohydrates, fatty acids and amino acids, is known to be irreversible. It liberates CO2 and generates NADH whose aerobic oxidation yields ATP but it does not operate in reverse as a biosynthetic pathway for CO2 assimilation. In 1966, our laboratory described a cyclic pathway for CO2 assimilation (Evans, Buchanan and Arnon 1966) that was unusual in two respects: (i) it provided the first instance of an obligate photoautotroph that assimilated CO2 by a pathway different from Calvin's reductive pentose phosphate cycle (Calvin 1962) and (ii) in its overall effect the new cycle was a reversal of the Krebs cycle. Named the 'reductive carboxylic acid cycle' (sometimes also called the reductive tricarboxylic acid cycle) the new cycle appeared to be the sole CO2 assimilation pathway in Chlorobium thiosulfatophilum (Evans et al. 1966) (now known as Chlorobium limicola forma thiosulfatophilum). Chlorobium is a photosynthetic green sulfur bacterium that grows anaerobically in an inorganic medium with sulfide and thiosulfate as electron donors and CO2 as an obligatory carbon source. In the ensuing years, the new cycle was viewed with skepticism. Not only was it in conflict with the prevailing doctrine that the 'one important property ... shared by all (our emphasis) autotrophic species is the assimilation of CO2 via the Calvin cycle' (McFadden 1973) but also some of its experimental underpinnings were challenged. It is only now that in the words of one of its early skeptics (Tabita 1988) 'a long and tortuous controversy' has ended with general acceptance of the reductive carboxylic acid cycle as a photosynthetic CO2 assimilation pathway distinct from the pentose cycle. (Henceforth, to minimize repetitiveness, the reductive pentose phosphate cycle will often be referred to as the pentose cycle and the reductive carboxylic acid cycle as the carboxylic

  9. Alternative Approach for predicting the performance of Irreversible Otto Cycle

    Directory of Open Access Journals (Sweden)

    Mohd Nadeem Khan

    2010-06-01

    Full Text Available The performance of an air-standard Otto cycle with variation of cycle peak temperature and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects cycle peak temperature and variable specific heats of working fluid on the cycle performance are analyzed. The results show that the effects of cycle peak temperature and variable specific heats of working fluid on the cycle performance are obvious, andthey should be considered in practice cycle analysis. The results obtained from this work are presented in the form of generalized equations for specific work output in term of compressor efficiency, turbine efficiency and compression ratio of the cycle. These equations can be used by the designers for predicting the performance of real otto cycle. The results obtained in this paper may provide guidance for the design of practice internal combustion engines.

  10. Market Diffusion of Extended Cycle Hormonal Contraceptives

    Directory of Open Access Journals (Sweden)

    Megen Leeds Schumacher, Pharm.D.

    2012-01-01

    Full Text Available Background: Extended cycle hormonal contraceptives (e.g. Seasonale, Seasonique when introduced in 2003 were considered a very novel approach to contraception. The idea of manipulating the menstrual cycle so that women would experience just four menstruations a year was radical and was assumed to be responsible for the slow acceptance rate among the general public.Objective: This report analyzes two different aspects of the acceptance of this unique idea in the population. The first was the level of usage of extended cycle hormonal contraceptives in the general population, which was measured by a review of sales figures over time in the United States. The second was an examination of market diffusion as it relates to consumer perceptions regarding the characteristics of these products.Methods: To determine the degree of usage of extended cycle hormonal contraceptives the yearly sales, in terms of units sold, were compared with that of other leading methods of hormonal contraception. Along with the data, survey answers were obtained from 65 women who volunteered to participate in the study. Participants were selected randomly to represent the target population to assess the level of awareness about the benefits, risks, and any other concerns regarding the use of extended cycle hormonal contraceptives.Results: The yearly sales data of units sold showed a definitive increase in the sales of extended cycle hormonal contraceptives since their release on the market. The survey results showed an overwhelming awareness in the study population about the extended regimen. However, only about half of the women in the survey group were aware of its benefits. The main concern reported was the perceived significant side effect profile.Conclusion: Though awareness about the extended cycle hormonal contraception regimen was widespread, the survey population was not well informed about the advantages and the disadvantages regarding the degree of severity of side

  11. Life cycle of cytosolic prions.

    Science.gov (United States)

    Hofmann, Julia; Vorberg, Ina

    2013-01-01

    Prions are self-templating protein aggregates that were originally identified as the causative agent of prion diseases in mammals, but have since been discovered in other kingdoms. Mammalian prions represent a unique class of infectious agents that are composed of misfolded prion protein. Prion proteins usually exist as soluble proteins but can refold and assemble into highly ordered, self-propagating prion polymers. The prion concept is also applicable to a growing number of non-Mendelian elements of inheritance in lower eukaryotes. While prions identified in mammals are clearly pathogens, prions in lower eukaryotes can be either detrimental or beneficial to the host. Prion phenotypes in fungi are transmitted vertically from mother to daughter cells during cell division and horizontally during mating or abortive mating, but extracellular phases have not been reported. Recent findings now demonstrate that in a mammalian cell environment, protein aggregates derived from yeast prion domains exhibit a prion life cycle similar to mammalian prions propagated ex vivo. This life cycle includes a soluble state of the protein, an induction phase by exogenous prion fibrils, stable replication of prion entities, vertical transmission to progeny and natural horizontal transmission to neighboring cells. Our data reveal that mammalian cells contain all co-factors required for cytosolic prion propagation and dissemination. This has important implications for understanding prion-like properties of disease-related protein aggregates. In light of the growing number of identified functional amyloids, cell-to-cell propagation of cytosolic protein conformers might not only be relevant for the spreading of disease-associated proteins, but might also be of more general relevance under non-disease conditions.

  12. Fuel Cycle System Analysis Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Steven J. Piet; Brent W. Dixon; Dirk Gombert; Edward A. Hoffman; Gretchen E. Matthern; Kent A. Williams

    2009-06-01

    This Handbook aims to improve understanding and communication regarding nuclear fuel cycle options. It is intended to assist DOE, Campaign Managers, and other presenters prepare presentations and reports. When looking for information, check here. The Handbook generally includes few details of how calculations were performed, which can be found by consulting references provided to the reader. The Handbook emphasizes results in the form of graphics and diagrams, with only enough text to explain the graphic, to ensure that the messages associated with the graphic is clear, and to explain key assumptions and methods that cause the graphed results. Some of the material is new and is not found in previous reports, for example: (1) Section 3 has system-level mass flow diagrams for 0-tier (once-through), 1-tier (UOX to CR=0.50 fast reactor), and 2-tier (UOX to MOX-Pu to CR=0.50 fast reactor) scenarios - at both static and dynamic equilibrium. (2) To help inform fast reactor transuranic (TRU) conversion ratio and uranium supply behavior, section 5 provides the sustainable fast reactor growth rate as a function of TRU conversion ratio. (3) To help clarify the difference in recycling Pu, NpPu, NpPuAm, and all-TRU, section 5 provides mass fraction, gamma, and neutron emission for those four cases for MOX, heterogeneous LWR IMF (assemblies mixing IMF and UOX pins), and a CR=0.50 fast reactor. There are data for the first 10 LWR recycle passes and equilibrium. (4) Section 6 provides information on the cycle length, planned and unplanned outages, and TRU enrichment as a function of fast reactor TRU conversion ratio, as well as the dilution of TRU feedstock by uranium in making fast reactor fuel. (The recovered uranium is considered to be more pure than recovered TRU.) The latter parameter impacts the required TRU impurity limits specified by the Fuels Campaign. (5) Section 7 provides flows for an 800-tonne UOX separation plant. (6) To complement 'tornado' economic

  13. First Cycle Games

    Directory of Open Access Journals (Sweden)

    Benjamin Aminof

    2014-04-01

    Full Text Available First cycle games (FCG are played on a finite graph by two players who push a token along the edges until a vertex is repeated, and a simple cycle is formed. The winner is determined by some fixed property Y of the sequence of labels of the edges (or nodes forming this cycle. These games are traditionally of interest because of their connection with infinite-duration games such as parity and mean-payoff games. We study the memory requirements for winning strategies of FCGs and certain associated infinite duration games. We exhibit a simple FCG that is not memoryless determined (this corrects a mistake in \\it Memoryless determinacy of parity and mean payoff games: a simple proof by Björklund, Sandberg, Vorobyov (2004 that claims that FCGs for which Y is closed under cyclic permutations are memoryless determined. We show that Θ(n! memory (where n is the number of nodes in the graph, which is always sufficient, may be necessary to win some FCGs. On the other hand, we identify easy to check conditions on Y (i.e., Y is closed under cyclic permutations, and both Y and its complement are closed under concatenation that are sufficient to ensure that the corresponding FCGs and their associated infinite duration games are memoryless determined. We demonstrate that many games considered in the literature, such as mean-payoff, parity, energy, etc., satisfy these conditions. On the complexity side, we show (for efficiently computable Y that while solving FCGs is in PSPACE, solving some families of FCGs is PSPACE-hard.

  14. The software life cycle

    CERN Document Server

    Ince, Darrel

    1990-01-01

    The Software Life Cycle deals with the software lifecycle, that is, what exactly happens when software is developed. Topics covered include aspects of software engineering, structured techniques of software development, and software project management. The use of mathematics to design and develop computer systems is also discussed. This book is comprised of 20 chapters divided into four sections and begins with an overview of software engineering and software development, paying particular attention to the birth of software engineering and the introduction of formal methods of software develop

  15. Elementary cycles of time

    Directory of Open Access Journals (Sweden)

    Dolce Donatello

    2013-09-01

    Full Text Available Elementary particles, i.e. the basic constituents of nature, are characterized by quantum recurrences in time. The flow of time of every physical system can be therefore decomposed in elementary cycles of time. This allows us to enforce the local nature of relativistic time, yielding interesting unified descriptions of fundamental aspects of modern physics, as shown in recent publications. Every particle can be regarded as a reference clock with time resolution of the order of the Compton time particle, many orders of magnitude more accurate than the atomic clocks. Here we report basic implications about the resulting notion of time.

  16. Quantum thermodynamic cooling cycle

    CERN Document Server

    Palao, J P; Gordon, J M; Palao, Jose P.; Kosloff, Ronnie; Gordon, Jeffrey M.

    2001-01-01

    The quantum-mechanical and thermodynamic properties of a 3-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force - the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultra-low temperatures, is determined and shown to respect the recently-established fundamental bound based on the second and third laws of thermodynamics.

  17. Cycling Joule Thomson refrigerator

    Science.gov (United States)

    Tward, E.

    1983-01-01

    A symmetrical adsorption pump/compressor system having a pair of mirror image legs and a Joule Thomson expander, or valve, interposed between the legs thereof for providing a, efficient refrigeration cycle is described. The system further includes a plurality of gas operational heat switches adapted selectively to transfer heat from a thermal load and to transfer or discharge heat through a heat projector, such as a radiator or the like. The heat switches comprise heat pressurizable chambers adapted for alternate pressurization in response to adsorption and desorption of a pressurizing gas confined therein.

  18. Sometimes "Newton's Method" Always "Cycles"

    Science.gov (United States)

    Latulippe, Joe; Switkes, Jennifer

    2012-01-01

    Are there functions for which Newton's method cycles for all non-trivial initial guesses? We construct and solve a differential equation whose solution is a real-valued function that two-cycles under Newton iteration. Higher-order cycles of Newton's method iterates are explored in the complex plane using complex powers of "x." We find a class of…

  19. Revenue cycle management: part I.

    Science.gov (United States)

    Crew, Matt

    2006-01-01

    The revenue cycle starts long before a patient is seen and continues until a claim is completely resolved. Each step in the revenue cycle must be clearly defined and easy to follow. Use of various tools such as templates, forms, reports, spreadsheets, and components of your practice management system will help to provide the consistency you need for profitable revenue cycle management.

  20. Entrepreneurship and the Business Cycle

    NARCIS (Netherlands)

    Ph.D. Koellinger (Philipp); A.R. Thurik (Roy)

    2011-01-01

    textabstractWe find new empirical regularities in the business cycle in a cross-country panel of 22 OECD countries for the period 1972-2007; entrepreneurship Granger-causes the cycles of the world economy. Furthermore, the entrepreneurial cycle is positively affected by the national unemployment

  1. Generalized periodic and generalized Boolean rings

    Directory of Open Access Journals (Sweden)

    Howard E. Bell

    2001-01-01

    Full Text Available We prove that a generalized periodic, as well as a generalized Boolean, ring is either commutative or periodic. We also prove that a generalized Boolean ring with central idempotents must be nil or commutative. We further consider conditions which imply the commutativity of a generalized periodic, or a generalized Boolean, ring.

  2. Menstrual cycle pattern and fertility

    DEFF Research Database (Denmark)

    Kolstad, Henrik A.; Bonde, Jens Peter; Hjøllund, Niels Henrik;

    1999-01-01

    OBJECTIVE: To characterize how the menstrual cycle pattern relates to fertility regardless of potential biases caused by inappropriate coital timing during the menstrual cycle or early embryonal loss. DESIGN: Prospective follow-up study. SETTING: Healthy couples recruited throughout Denmark. PATI...... 0.09-0.68). When the combined effect of cycle variation and cycle length was assessed, cycle variation was a persistent strong predictor of fecundity. CONCLUSION(S): The mechanisms of the present findings probably are female functional disturbances in ovulation, conception, implantation...

  3. Astronomical forcing of sedimentary cycles of Late Eocene Liushagang Formation in the Bailian Sag, Fushan Depression, Beibuwan Basin, South China Sea

    Institute of Scientific and Technical Information of China (English)

    曹海洋; 金思丁; 孙鸣; 王华

    2016-01-01

    Sediments in the Liushagang Formation of Late Eocene form a group of key hydrocarbon play fairways in the Beibuwan Basin, South China Sea. As an important reservoir-forming combination, the Liushagang Formation consists of deltaic siliciclastic and show clear sedimentary cyclicity. According to paleontology research and stratigraphic correlation, the boundary between Liushagang Formation (Els) and Weizhou Formation (Ewz) is regarded as the Eocene-Oligocene boundary. The oxygen isotope dating for well cores from the top of the first Member of Liushagang Formation (Els1) and the bottom of the third Member of Weizhou Formation (Ewz3) give an isochron age of 35.2 Ma. Here, we use GR logging data as a paleoenvironmental proxy to conduct a detailed cyclostratigraphic study of the Els1 in the Bailian Sag, Fushan Depression. Power spectra, evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in Els1. The ratios of cycle wavelengths in these stratigraphic units are 21׃5׃2.8׃1.2׃1, and are interpreted as Milankovitch cycles of 400 ka and 96 ka eccentricity, 52 ka obliquity, 22 ka and 19 ka precession cycles, respectively. An astronomical time scale is established by tuning filtered 96 ka eccentricity cycles to a target curve of Well L2 in the Bailian Sag. Based on regional stratigraphic framework, combined with seismic, cores and logging data, the HST of the first member of the Liushagang Formation (Els1) delta in Well L2 was divided into six parasequence sets named Ps1-Ps6. According to the spectrum analysis by Simple Lomb periodogram from PAST program packages, the sediment accumulation rate of each parasequence sets first increased and then decreased as time went by. The sediment accumulation rate of Ps4 reached the maximum (0.127 m/ka) during the most prosperous period of delta prograding. Finally, the duration of each period of parasequence sets and more accurate geological age were calculated on the basis of

  4. General(es) remisión de V. escuelas general(es).

    OpenAIRE

    2011-01-01

    [ES] Definición del término General(es) remisión de V. escuelas general(es). en el diccionario Dicter. [EN] Definition of the word General(es) remisión de V. escuelas general(es). in the dictionary Dicter.

  5. Science Illiteracy: Breaking the Cycle

    Science.gov (United States)

    Lebofsky, L. A.; Lebofsky, N. R.

    2003-12-01

    At the University of Arizona, as at many state universities and colleges, the introductory science classes for non-science majors may be the only science classes that future K--8 teachers will take. The design of the UA's General Education program requires all future non-science certified teachers to take the General Education science classes. These classes are therefore an ideal venue for the training of the state's future teachers. Many students, often including future teachers, are ill-prepared for college, i.e., they lack basic science content knowledge, basic mathematics skills, and reading and writing skills. They also lack basic critical thinking skills and study skills. It is within this context that our future teachers are trained. How do we break the cycle of science illiteracy? There is no simple solution, and certainly not a one-size-fits-all panacea that complements every professor's style of instruction. However, there are several programs at the University of Arizona, and also principles that I apply in my own classes, that may be adaptable in other classrooms. Assessment of K--12 students' learning supports the use of inquiry-based science instruction. This approach can be incorporated in college classes. Modeling proven and productive teaching methods for the future teachers provides far more than ``just the facts,'' and all students gain from the inquiry approach. Providing authentic research opportunities employs an inquiry-based approach. Reading (outside the textbook) and writing provide feedback to students with poor writing and critical thinking skills. Using peer tutors and an instant messaging hot line gives experience to the tutors and offers "comfortable" assistance to students.

  6. Open cycle thermoacoustics

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Robert Stowers [Georgia Inst. of Technology, Atlanta, GA (United States)

    2000-01-01

    A new type of thermodynamic device combining a thermodynamic cycle with the externally applied steady flow of an open thermodynamic process is discussed and experimentally demonstrated. The gas flowing through this device can be heated or cooled in a series of semi-open cyclic steps. The combination of open and cyclic flows makes possible the elimination of some or all of the heat exchangers (with their associated irreversibility). Heat is directly exchanged with the process fluid as it flows through the device when operating as a refrigerator, producing a staging effect that tends to increase First Law thermodynamic efficiency. An open-flow thermoacoustic refrigerator was built to demonstrate this concept. Several approaches are presented that describe the physical characteristics of this device. Tests have been conducted on this refrigerator with good agreement with a proposed theory.

  7. The planning cycle.

    Science.gov (United States)

    Johnson, William

    2005-01-01

    Information technology planning can be described as a continuous cyclical process composed of three phases whose primary purpose is optimum allocation of scarce resources. In the assessment phase, planners assess user needs, environmental factors, business objectives, and IT infrastructure needs to develop IT projects that address needs in each of these areas. A major goal of this phase is to develop a broad IT inventory. The prioritization phase seeks to ensure optimum allocation of scarce resources by prioritizing ITprojects based on: Costs--total life cycle costs. Benefits--both quantitative and non-quantitative, including support for the organization's strategic business objectives. Risks--subjective assessments of technological and non-technological risks. Implementation requirements--time and personnel requirements to implement the system. The scheduling phase incorporates sequencing considerations, personnel availability, and budgetary constraints to produce an IT plan in which project priorities are adjusted to meet organizational realities.

  8. The supercontinent cycle

    Energy Technology Data Exchange (ETDEWEB)

    Nance, R.D.; Worsley, T.R.; Moody, J.B.

    1988-07-01

    This paper discusses a new theory of plate tectonics which proposes that Pangaea was only the most recent in a series of supercontinents that have been breaking up and reassembling every 500 million years or so. The cycle, driven by heat percolating up from the mantle, splits continents and drives interrelated processes that shape the earth's geology and climate and play a role in biological evolution. The framework of the supercontinent theory makes it possible to understand the timing of changes in sea level that have taken place in the past 570 million years, and also helps to explain periods of intense mountain building, episodes of glaciation, and changes in the nature of life on the earth.

  9. The Pyrogenic Carbon Cycle

    Science.gov (United States)

    Bird, Michael I.; Wynn, Jonathan G.; Saiz, Gustavo; Wurster, Christopher M.; McBeath, Anna

    2015-05-01

    Pyrogenic carbon (PyC; includes soot, char, black carbon, and biochar) is produced by the incomplete combustion of organic matter accompanying biomass burning and fossil fuel consumption. PyC is pervasive in the environment, distributed throughout the atmosphere as well as soils, sediments, and water in both the marine and terrestrial environment. The physicochemical characteristics of PyC are complex and highly variable, dependent on the organic precursor and the conditions of formation. A component of PyC is highly recalcitrant and persists in the environment for millennia. However, it is now clear that a significant proportion of PyC undergoes transformation, translocation, and remineralization by a range of biotic and abiotic processes on comparatively short timescales. Here we synthesize current knowledge of the production, stocks, and fluxes of PyC as well as the physical and chemical processes through which it interacts as a dynamic component of the global carbon cycle.

  10. Krebs Cycle Wordsearch

    Science.gov (United States)

    Helser, Terry L.

    2001-04-01

    This puzzle embeds 46 names, terms, abbreviations, and acronyms about the citric acid (Krebs) cycle in a 14- x 17-letter matrix. A descriptive narrative beside it describes important features of the pathway. All the terms a student needs to find are embedded there with the first letter followed by underlined blanks to be completed. Therefore, the students usually must find the terms to know how to spell them, correctly fill in the blanks in the narrative with the terms, and then find and highlight the terms in the letter matrix. When all are found, the 24 unused letters complete a sentence that describes a major feature of this central pathway. The puzzle may be used as homework, an extra-credit project, or a group project in the classroom in any course where basic metabolism is learned. It disguises as fun the hard work needed to learn the names of the intermediates, enzymes, and cofactors.

  11. Oestrous cycles in Bos taurus cattle.

    Science.gov (United States)

    Forde, N; Beltman, M E; Lonergan, P; Diskin, M; Roche, J F; Crowe, M A

    2011-04-01

    The oestrous cycle in cattle lasts for 18-24 days. It consists of a luteal phase (14-18 days) and a follicular phase (4-6 days). During the cycle there are generally two (dairy cows) or three (heifers and beef cows) waves of ovarian follicle growth. Each wave of follicle growth consists of a period of emergence of a cohort of follicles, selection of a dominant follicle and either atresia or ovulation of the dominant follicle. These waves of follicle growth, initially established during the early pre-pubertal period of development occur throughout the entire cycle, with only the dominant follicle (DF) of the final wave coinciding with the follicular phase that undergoes final maturation and ovulation. Ovarian functions (follicle growth, ovulation, luteinisation and luteolysis) are regulated by the endocrine hormones of the hypothalamus (gonadotrophin-releasing hormone), anterior pituitary (follicle-stimulating hormone and luteinising hormone), ovaries (progesterone, oestradiol and inhibins) and the uterus (prostaglandin F2α). In postpartum cows resumption of regular oestrous cycles (in addition to uterine involution) is fundamental for re-establishment of pregnancy.

  12. Goethermal power plant with Kalina cycle

    Energy Technology Data Exchange (ETDEWEB)

    Renz, M.; Filipovic, A. [M+W Zander Facility Engineering GmbH, Stuttgart (Germany). Marketing-Communications

    2005-04-01

    Several factors are creating an increased market for small power plant technology. These include the need for distributed/decentralised power systems, the need to generate more electricity by non-combustion renewable processes, the need for sustainable power for economic growth in developing countries and the deregulation and privatization of the electrical generation sector. Basically there are 2 alternate principles to improve the efficiency of the Rankine steam cycle for low temperature applications: Replacing water by a one-component fluid with lower boiling points, e.g. different organic substances like n-pentane, isobutene, perfluoropen-tane. (Organic Rankine Cycle, ORC). Replacing water by a binary working fluid like ammonia-water as proposed by Kalina. Kalina and ORC power cycles are primarily used for lower temperature heat sources, such as goethermal or waste-heat recovery. The primary advantage of this technology is the operation at low temperature which is given at renewable heat sources and waste heat. Further the power cycles are simple and generally can be operated remotely, without licensed operators, allowing for increased use of self-diagnostics. M+W Zander is working closely with partners to establish an alternative technology for geothermal applications. (orig.)

  13. Ocean iron cycle

    Science.gov (United States)

    Boyd, Philip W.

    Interest in the biogeochemical cycle of iron has grown rapidly over the last two decades, due to the potential role of this element in modulating global climate in the geological past and ocean productivity in the present day. This trace metal has a disproportionately large effect (1 × 105 C:Fe) on photosynthetic carbon fixation by phytoplankton. In around one third of the open ocean, so-called high-nitrate low-chlorophyll (HNLC) regions, the resident phytoplankton have low growth rates despite an abundance of plant nutrients. This is due to the low supply of iron. Iron is present in the ocean in three phases, dissolved, colloidal, and particulate (biogenic and lithogenic). However, iron chemistry is complex with interactions between chemistry and biology such as the production of iron-binding siderophores by oceanic bacteria. This results in the interplay of inorganic chemistry, photochemistry, and organic complexation. Sources of new iron include dust deposition, upwelling of iron-rich deep waters, and the resuspension and lateral transport of sediments. Sinks for iron are mainly biological as evidenced by the vertical nutrient-like profile for dissolved iron in the ocean. Iron is rapidly recycled by the upper ocean biota within a so-called "ferrous wheel." The fe ratio [(new iron)/(new + regenerated iron)] provides an index of the relative supply of iron to the biota by new versus recycled iron. Over the last 15 years, interest in the potential role of iron in shaping climate in the geological past resulted in some of the most ambitious experiments in oceanography: large-scale (i.e., 50-1000 km2) iron enrichment of HNLC waters. They have provided valuable insights into how iron supply influences the biogeochemical cycles of elements such as carbon, sulfur, silicon, nitrogen, and phosphate.

  14. Climate Cycling on Early Mars Caused by the Carbonate-Silicate Cycle

    CERN Document Server

    Batalha, Natasha E; Haqq-Misra, Jacob; Kasting, James F

    2016-01-01

    For decades, scientists have tried to explain the evidence for fluvial activity on early Mars, but a consensus has yet to emerge regarding the mechanism for producing it. One hypothesis suggests early Mars was warmed by a thick greenhouse atmosphere. Another suggests that early Mars was generally cold but was warmed occasionally by impacts or by episodes of enhanced volcanism. These latter hypotheses struggle to produce the amounts of rainfall needed to form the martian valleys, but are consistent with inferred low rates of weathering compared to Earth. Here, we provide a geophysical mechanism that could have induced cycles of glaciation and deglaciation on early Mars. Our model produces dramatic climate cycles with extended periods of glaciation punctuated by warm periods lasting up to 10 Myr, much longer than those generated in other episodic warming models. The cycles occur because stellar insolation was low, and because CO2 outgassing is not able to keep pace with CO2 consumption by silicate weathering fo...

  15. Overview of cycling injuries: results of a cycling club survey.

    Science.gov (United States)

    Decalzi, Javier F; Narvy, Steven J; Vangsness, C Thomas

    2013-04-01

    Participation in competitive bicycling has increased substantially over the past decade, and bicycle injuries have increased accordingly. Cycling has been reported in several studies to have higher rates of injury than other sports and recreational activities; accordingly, riders must be cognizant of the potential for injury and protect themselves appropriately. The purpose of the current study was to survey an established competitive Los Angeles-based road cycling team to determine the epidemiology of and circumstances for traumatic cycling injuries.

  16. Measurement of single cycle and sub-cycle pulse duration

    Institute of Scientific and Technical Information of China (English)

    Zhenglie Gong(龚正烈); Wenzhuo Ge(葛文卓); Guizhong Zhang(张贵忠); Wanghua Xiang(向望华)

    2004-01-01

    This paper suggests that the linear interferometric correlation (LFC) can be used to measure pulse duration of a few cycles, single cycle or even sub-cycle light pulse. The relations between pulsewidth and LFC curve are derived for Gaussian- and hyperbolic secant-shaped pules. This new method abandons focusing,frequency doubling and filtering in the traditional second order correlation method, meanwhile the signalto-noise ratio (SNR) is improved.

  17. WBN-1 Cycle 10 TPBAR Tritium Release, Deduced From Analysis of RCS Data TTP-1-3046-00, Rev 0

    Energy Technology Data Exchange (ETDEWEB)

    Shaver, Mark W.; Niehus, Mark T.; Love, Edward F.

    2012-02-19

    This document contains the calculation of the TPBAR tritium release from the Mark 9.2 design TPBARs irradiated in WBN cycle 10. The calculation utilizes the generalized cycle analysis methodology given in TTP-1-3045 Rev. 0.

  18. Mammalian cycles: internally defined periods and interaction-driven amplitudes

    Directory of Open Access Journals (Sweden)

    LR Ginzburg

    2015-08-01

    Full Text Available The cause of mammalian cycles—the rise and fall of populations over a predictable period of time—has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles’ periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016 to be of extraordinarily low amplitude.

  19. Mammalian cycles: internally defined periods and interaction-driven amplitudes

    Science.gov (United States)

    Krebs, CJ

    2015-01-01

    The cause of mammalian cycles—the rise and fall of populations over a predictable period of time—has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles’ periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016) to be of extraordinarily low amplitude. PMID:26339557

  20. Limit Cycle Prediction Based on Evolutionary Multiobjective Formulation

    Directory of Open Access Journals (Sweden)

    M. Katebi

    2009-01-01

    In the second part, SIDF is extended to the class of nonlinear multiinput multioutput (MIMO systems containing separable nonlinear elements of any general form. In both cases linearized harmonic balance equations are derived and the search for a limit cycle is formulated as a multiobjective problem. Multiobjective genetic algorithm (MOGA is utilized to search the space of parameters of theoretically possible limit cycle operations. Case studies are presented to demonstrate the effectiveness of the proposed approach.

  1. The global nitrogen cycle: Past, present and future

    Institute of Scientific and Technical Information of China (English)

    James N. Galloway

    2005-01-01

    Food and energy production converts N2 to reactive N species that cascade through environmental reservoirs and in the process impact human and ecosystem health. This presentation will examine the impact of increased N mobilization on the global N cycle by contrasting N distribution in the late-19th century with those of the late-20th century. The presentation will give a general overview of regional differences and will conclude with a projection of the global N cycle for 2050.

  2. Investigation on the Quasi-Cycle of Black Hole Spin

    Institute of Scientific and Technical Information of China (English)

    WANG Ding-Xiong; XIAO Kan; LEI Wei-Hua

    2001-01-01

    A reverse condition of accretion flow and its constraints on black hole spin in the quasi-cycle are proposed. It is shown that the necessary condition for the quasi-cycle is that the closed magnetic field lines must dominate over the open ones at the horizon. The efficiency of converting accreted rest mass into radiation energy in the quasicycle is proved to increase with the strength of the magnetic transfer process. In addition, a general expression for the efficiency is derived.

  3. Thermodynamic study of air-cycle and mercury-vapor-cycle systems for refrigerating cooling air for turbines or other components

    Science.gov (United States)

    Nachtigall, Alfred J; Freche, John C; Esgar, Jack B

    1956-01-01

    An analysis of air refrigeration systems indicated that air cycles are generally less satisfactory than simple heat exchangers unless high component efficiencies and high values of heat-exchanger effectiveness can be obtained. A system employing a mercury-vapor cycle appears to be feasible for refrigerating air that must enter the system at temperature levels of approximately 1500 degrees R, and this cycle is more efficient than the air cycle. Weight of the systems was not considered. The analysis of the systems is presented in a generalized dimensionless form.

  4. Modeling the hydrological cycle on Mars

    Directory of Open Access Journals (Sweden)

    Ghada Machtoub

    2012-03-01

    Full Text Available The study provides a detailed analysis of the hydrological cycle on Mars simulated with a newly developed microphysical model, incorporated in a spectral Mars General Circulation Model. The modeled hydrological cycle is compared well with simulations of other global climate models. The simulated seasonal migration ofwater vapor, circulation instability, and the high degree of temporal variability of localized water vapor outbursts are shown closely consistent with recent observations. The microphysical parameterization provides a significant improvement in the modeling of ice clouds evolved over the tropics and major ancient volcanoes on Mars. The most significant difference between the simulations presented here and other GCM results is the level at which the water ice clouds are found. The model findings also support interpretation of observed thermal anomalies in the Martian tropics during northern spring and summer seasons.

  5. HST Cycle 19 Exposure Time Calculators

    Science.gov (United States)

    York, Brian Andrew; Diaz, R. I.; Busko, I.; Greenfield, P.; Laidler, V.; Miller, T.; Sienkiewicz, M.; Sosey, M.

    2010-05-01

    The Exposure Time Calculator (ETC) is a web-based application that assists users in calculating the exposure time needed for their HST observations, or the Signal-to-Noice Ratio (SNR) they can attain with a given HST observing time. These quantities are key for the preparation of proposals and observations during Phase I and Phase II of the proposing cycle and therefore have to be sufficiently accurate for each of the supported observing modes of all the HST instruments. Developing a general tool that shares communality among the different instruments is complicated, not only form the point of view of attaining accuracy of the calculations but also regarding reliability, portability, and maintainability. We are currently developing a new version of the ETC for Cycle 19 in Python to improve these qualities and to provide a basis for JWST Exposure Time Calculators. This poster describes the improvements over the previous ETC and the current status of the new version.

  6. Methodologies for Social Life Cycle Assessment

    DEFF Research Database (Denmark)

    Jørgensen, Andreas; Le Bocq, Agathe; Nazakina, Liudmila

    2008-01-01

    Goal, Scope and Background. In recent years several different approaches towards Social Life Cycle Assessment (SLCA) have been developed. The purpose of this review is to compare these approaches in order to highlight methodological differences and general shortcomings. SLCA has several...... stage in the product life cycle. Another very important difference among the proposals is their position towards the use of generic data. Several of the proposals argue that social impacts are connected to the conduct of the company leading to the conclusion that each individual company in the product...... and formulation of indicators. The indicators address a wide variety of issues; some approaches focus on impacts created in the very close proximity of the processes included in the product system, whereas others focus on the more remote societal consequences. Only very little focus has been given to the use...

  7. MEDEX: a general overview

    Science.gov (United States)

    Jansa, A.; Alpert, P.; Arbogast, P.; Buzzi, A.; Ivancan-Picek, B.; Kotroni, V.; Llasat, M. C.; Ramis, C.; Richard, E.; Romero, R.; Speranza, A.

    2014-08-01

    The general objective of the international MEDiterranean EXperiment (MEDEX) was the better understanding and forecasting of cyclones that produce high impact weather in the Mediterranean. This paper reviews the motivation and foundation of MEDEX, the gestation, history and organisation of the project, as well as the main products and scientific achievements obtained from it. MEDEX obtained the approval of World Meteorological Organisation (WMO) and can be considered as framed within other WMO actions, such as the ALPine EXperiment (ALPEX), the Mediterranean Cyclones Study Project (MCP) and, to a certain extent, THe Observing System Research and Predictability EXperiment (THORPEX) and the HYdrological cycle in Mediterranean EXperiment (HyMeX). Through two phases (2000-2005 and 2006-2010), MEDEX has produced a specific database, with information about cyclones and severe or high impact weather events, several main reports and a specific data targeting system field campaign (DTS-MEDEX-2009). The scientific achievements are significant in fields like climatology, dynamical understanding of the physical processes and social impact of cyclones, as well as in aspects related to the location of sensitive zones for individual cases, the climatology of sensitivity zones and the improvement of the forecasts through innovative methods like mesoscale ensemble prediction systems.

  8. Removing Cycles in Esterel Programs

    Directory of Open Access Journals (Sweden)

    Lukoschus Jan

    2007-01-01

    Full Text Available Esterel belongs to the family of synchronous programming languages, which are affected by cyclic signal dependencies. This prohibits a static scheduling, limiting the choice of available compilation techniques for programs with such cycles. This work proposes an algorithm that, given a constructive synchronous Esterel program, performs a semantics-preserving source code level transformation that removes cyclic signal dependencies. The transformation is divided into two parts: detection of cycles and iterative resolution of these cycles. It is based on the replacement of cycle signals by a signal expression involving no other cycle signals, thereby breaking the cycle. This transformation of cyclic Esterel programs enables the use of efficient compilation techniques, which are only available for acyclic programs. Furthermore, experiments indicate that the code transformation can even improve code quality produced by compilers that can already handle cyclic programs.

  9. Removing Cycles in Esterel Programs

    Directory of Open Access Journals (Sweden)

    Reinhard von Hanxleden

    2007-05-01

    Full Text Available Esterel belongs to the family of synchronous programming languages, which are affected by cyclic signal dependencies. This prohibits a static scheduling, limiting the choice of available compilation techniques for programs with such cycles. This work proposes an algorithm that, given a constructive synchronous Esterel program, performs a semantics-preserving source code level transformation that removes cyclic signal dependencies. The transformation is divided into two parts: detection of cycles and iterative resolution of these cycles. It is based on the replacement of cycle signals by a signal expression involving no other cycle signals, thereby breaking the cycle. This transformation of cyclic Esterel programs enables the use of efficient compilation techniques, which are only available for acyclic programs. Furthermore, experiments indicate that the code transformation can even improve code quality produced by compilers that can already handle cyclic programs.

  10. Quantum Performance of Thermal Machines over Many Cycles

    Science.gov (United States)

    Watanabe, Gentaro; Venkatesh, B. Prasanna; Talkner, Peter; del Campo, Adolfo

    2017-02-01

    The performance of quantum heat engines is generally based on the analysis of a single cycle. We challenge this approach by showing that the total work performed by a quantum engine need not be proportional to the number of cycles. Furthermore, optimizing the engine over multiple cycles leads to the identification of scenarios with a quantum enhancement. We demonstrate our findings with a quantum Otto engine based on a two-level system as the working substance that supplies power to an external oscillator.

  11. Challenge of modelling the climate of the last glacial-interglacial cycle and millennial climate change as a background of evolution of modern Human

    Science.gov (United States)

    Abe-Ouchi, Ayako; Chan, Wing-Le; O'ishi, Ryouta; Obrochta, Stephen; Yokoyama, Yusuke; Kondo, Yasuhisa; Yoneda, Minoru

    2014-05-01

    The environment of the evolution of Homo-Sapience is characterized by the climate change of glacial-interglacial cycle (about 125 thousand years in the past), which includes frequent occurrence of abrupt climate change (Dansgaard Oeschger events, = D-O events) of millenial time scale during the marine isotope stage 3. I We will have an overview on our work which we investigate the glacial-interglacial climate change and D-O events and its influence on vegetation of Africa through Eurasia (Europe and Asia). The numerical simulations are based on several model types, a coupled atmosphere-ocean-land GCM, MIROC, developed in Japan as well as ice sheet model IcIES, and a dynamical vegetation model LPJ. The condition that is given and changed for each time period is the following: orbital parameter (so called Milankovitch forcing) which influence the seasonal-latitudinal insolation, atmospheric content such as Carbon dioxide, ice sheet extent, and melt water from the ice sheet, which influence the ocean circulation and induce abrupt climate change. A transient ice sheet model behaviour is analyzed with the ice sheet model with climatic parameterization (Abe-Ouchi et al, 2013, Nature). Several snap shots of experimentsf are obtained both by slab ocean coupled GCM and AOGCM for the stadial - interstadial climate states and high resolution AGCM experiments are used to focus on the regional detail. The factors of climate change important for human evolution is examined and discussed, such as the change of climate, hydrology and vegetation associated with the abrupt climate change of D-O events is investigated.

  12. Entrepreneurship and the business cycle

    OpenAIRE

    Thurik, Roy

    2014-01-01

    Entrepreneurship has a cyclical component, raising two questions. Is the entrepreneurship cycle related to the business cycle? And is there causality? A two-way relationship between entrepreneurship and the business cycle would be in line with the two faces of entrepreneurs: as agents of change creating upswings (opportunity entrepreneurship) and as rational actors escaping unemployment by setting up a business (necessity entrepreneurship). Nascent entrepreneurship can indeed be precyclical, ...

  13. Numerical study of thermomagnetic cycle

    Science.gov (United States)

    Almanza, Morgan; Pasko, Alexandre; Mazaleyrat, Frédéric; LoBue, Martino

    2017-03-01

    We estimate the efficiency and power of a thermal energy harvesting thermodynamic cycle using a magnetocaloric material as active substance. The thermodynamic cycle is computed using an equation of state, either extrapolated from experimental data or deduced using a phenomenological Landau model. The magnetic work is then compared to the maximum work. Afterwards power is estimated using a simple thermal exchange model. Simulations of different cycles for different working points illustrate the tradeoff between power and efficiency.

  14. Cycling around a curve: the effect of cycling speed on steering and gaze behavior.

    Directory of Open Access Journals (Sweden)

    Pieter Vansteenkiste

    Full Text Available Although it is generally accepted that visual information guides steering, it is still unclear whether a curvature matching strategy or a 'look where you are going' strategy is used while steering through a curved road. The current experiment investigated to what extent the existing models for curve driving also apply to cycling around a curve, and tested the influence of cycling speed on steering and gaze behavior. Twenty-five participants were asked to cycle through a semicircular lane three consecutive times at three different speeds while staying in the center of the lane. The observed steering behavior suggests that an anticipatory steering strategy was used at curve entrance and a compensatory strategy was used to steer through the actual bend of the curve. A shift of gaze from the center to the inside edge of the lane indicates that at low cycling speed, the 'look where you are going' strategy was preferred, while at higher cycling speeds participants seemed to prefer the curvature matching strategy. Authors suggest that visual information from both steering strategies contributes to the steering system and can be used in a flexible way. Based on a familiarization effect, it can be assumed that steering is not only guided by vision but that a short-term learning component should also be taken into account.

  15. Cycling around a curve: the effect of cycling speed on steering and gaze behavior.

    Science.gov (United States)

    Vansteenkiste, Pieter; Van Hamme, David; Veelaert, Peter; Philippaerts, Renaat; Cardon, Greet; Lenoir, Matthieu

    2014-01-01

    Although it is generally accepted that visual information guides steering, it is still unclear whether a curvature matching strategy or a 'look where you are going' strategy is used while steering through a curved road. The current experiment investigated to what extent the existing models for curve driving also apply to cycling around a curve, and tested the influence of cycling speed on steering and gaze behavior. Twenty-five participants were asked to cycle through a semicircular lane three consecutive times at three different speeds while staying in the center of the lane. The observed steering behavior suggests that an anticipatory steering strategy was used at curve entrance and a compensatory strategy was used to steer through the actual bend of the curve. A shift of gaze from the center to the inside edge of the lane indicates that at low cycling speed, the 'look where you are going' strategy was preferred, while at higher cycling speeds participants seemed to prefer the curvature matching strategy. Authors suggest that visual information from both steering strategies contributes to the steering system and can be used in a flexible way. Based on a familiarization effect, it can be assumed that steering is not only guided by vision but that a short-term learning component should also be taken into account.

  16. An early solar dynamo prediction: Cycle 23 is approximately cycle 22

    Science.gov (United States)

    Schatten, Kenneth H.; Pesnell, W. Dean

    1993-01-01

    In this paper, we briefly review the 'dynamo' and 'geomagnetic precursor' methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the magnification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, through the development of the 'Solar Dynamo Amplitude' (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 210 +/- 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 170 +/- 25. This suggests that solar cycle #23 will be large, comparable to cycle #22. The estimated peak is expected to occur near 1999.7 +/- 1 year. Since the current approach is novel (using data prior to solar minimum), these estimates may improve when the upcoming solar minimum is reached.

  17. Energy system feasibility study of an Otto cycle/Stirling cycle hybrid automotive engine

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Barry; McGovern, Jim [Department of Mechanical Engineering, Dublin Institute of Technology, Dublin (Ireland)

    2010-02-15

    The aim of this study was to investigate the feasibility of utilising a Stirling cycle engine as an exhaust gas waste heat recovery device for an Otto cycle internal combustion engine (ICE) in the context of an automotive power plant. The hybrid arrangement would produce increased brake power output for a given fuel consumption rate when compared to an ICE alone. The study was dealt with from an energy system perspective with design practicalities such as power train integration, location of auxiliaries, manufacture costs and other general plant design considerations neglected. The study necessitated work in two distinct areas: experimental assessment of the performance characteristics of an existing automotive Otto cycle ICE and mathematical modelling of the Stirling cycle engine based on the output parameters of the ICE. It was subsequently found to be feasible in principle to generate approximately further 30% useful power in addition to that created by the ICE by using a Stirling cycle engine to capture waste heat expelled from the ICE exhaust gases over the complete range of engine operating speeds. (author)

  18. Life cycle replacement by gene introduction under an allee effect in periodical cicadas.

    Directory of Open Access Journals (Sweden)

    Yukiko Nariai

    Full Text Available Periodical cicadas (Magicicada spp. in the USA are divided into three species groups (-decim, -cassini, -decula of similar but distinct morphology and behavior. Each group contains at least one species with a 17-year life cycle and one with a 13-year cycle; each species is most closely related to one with the other cycle. One explanation for the apparent polyphyly of 13- and 17-year life cycles is that populations switch between the two cycles. Using a numerical model, we test the general feasibility of life cycle switching by the introduction of alleles for one cycle into populations of the other cycle. Our results suggest that fitness reductions at low population densities of mating individuals (the Allee effect could play a role in life cycle switching. In our model, if the 13-year cycle is genetically dominant, a 17-year cycle population will switch to a 13-year cycle given the introduction of a few 13-year cycle alleles under a moderate Allee effect. We also show that under a weak Allee effect, different year-classes ("broods" with 17-year life cycles can be generated. Remarkably, the outcomes of our models depend only on the dominance relationships of the cycle alleles, irrespective of any fitness advantages.

  19. Regenerative superheated steam turbine cycles

    Science.gov (United States)

    Fuller, L. C.; Stovall, T. K.

    1980-01-01

    PRESTO computer program was developed to analyze performance of wide range of steam turbine cycles with special attention given to regenerative superheated steam turbine cycles. It can be used to model standard turbine cycles, including such features as process steam extraction, induction and feedwater heating by external sources, peaking, and high back pressure. Expansion line efficiencies, exhaust loss, leakages, mechanical losses, and generator losses are used to calculate cycle heat rate and generator output. Program provides power engineer with flexible aid for design and analysis of steam turbine systems.

  20. Self-organizing biochemical cycles

    Science.gov (United States)

    Orgel, L. E.; Bada, J. L. (Principal Investigator)

    2000-01-01

    I examine the plausibility of theories that postulate the development of complex chemical organization without requiring the replication of genetic polymers such as RNA. One conclusion is that theories that involve the organization of complex, small-molecule metabolic cycles such as the reductive citric acid cycle on mineral surfaces make unreasonable assumptions about the catalytic properties of minerals and the ability of minerals to organize sequences of disparate reactions. Another conclusion is that data in the Beilstein Handbook of Organic Chemistry that have been claimed to support the hypothesis that the reductive citric acid cycle originated as a self-organized cycle can more plausibly be interpreted in a different way.

  1. The Photosynthetic Cycle

    Science.gov (United States)

    Calvin, Melvin

    1955-03-21

    A cyclic sequence of transformations, including the carboxylation of RuDP (ribulose diphosphate) and its re-formation, has been deduced as the route for the creation of reduced carbon compounds in photosynthetic organisms. With the demonstration of RuDP as substrate for the carboxylation in a cell-free system, each of the reactions has now been carried out independently in vitro. Further purification of this last enzyme system has confirmed the deduction that the carboxylation of RuDP leads directly to the two molecules of PGA (phosphoglyceric acid) involving an internal dismutation and suggesting the name "carboxydismutase" for the enzyme. As a consequence of this knowledge of each of the steps in the photosynthetic CO{sub 2} reduction cycle, it is possible to define the reagent requirements to maintain it. The net requirement for the reduction of one molecule of CO{sub 2} is four equivalents of [H]and three molecules of ATP (adenine triphosphate). These must ultimately be supplied by the photochemical reaction. Some possible ways in which this may be accomplished are discussed.

  2. Reproductive cycle of goats.

    Science.gov (United States)

    Fatet, Alice; Pellicer-Rubio, Maria-Teresa; Leboeuf, Bernard

    2011-04-01

    Goats are spontaneously ovulating, polyoestrous animals. Oestrous cycles in goats are reviewed in this paper with a view to clarifying interactions between cyclical changes in tissues, hormones and behaviour. Reproduction in goats is described as seasonal; the onset and length of the breeding season is dependent on various factors such as latitude, climate, breed, physiological stage, presence of the male, breeding system and specifically photoperiod. In temperate regions, reproduction in goats is described as seasonal with breeding period in the fall and winter and important differences in seasonality between breeds and locations. In tropical regions, goats are considered continuous breeders; however, restricted food availability often causes prolonged anoestrous and anovulatory periods and reduced fertility and prolificacy. Different strategies of breeding management have been developed to meet the supply needs and expectations of consumers, since both meat and milk industries are subjected to growing demands for year-round production. Hormonal treatments, to synchronize oestrus and ovulation in combination with artificial insemination (AI) or natural mating, allow out-of-season breeding and the grouping of the kidding period. Photoperiodic treatments coupled with buck effect now allow hormone-free synchronization of ovulation but fertility results after AI are still behind those of hormonal treatments. The latter techniques are still under study and will help meeting the emerging social demand of reducing the use of hormones for the management of breeding systems.

  3. Organic rankine cycle fluid

    Science.gov (United States)

    Brasz, Joost J.; Jonsson, Ulf J.

    2006-09-05

    A method of operating an organic rankine cycle system wherein a liquid refrigerant is circulated to an evaporator where heat is introduced to the refrigerant to convert it to vapor. The vapor is then passed through a turbine, with the resulting cooled vapor then passing through a condenser for condensing the vapor to a liquid. The refrigerant is one of CF.sub.3CF.sub.2C(O)CF(CF.sub.3).sub.2, (CF.sub.3).sub.2 CFC(O)CF(CF.sub.3).sub.2, CF.sub.3(CF.sub.2).sub.2C(O)CF(CF.sub.3).sub.2, CF.sub.3(CF.sub.2).sub.3C(O)CF(CG.sub.3).sub.2, CF.sub.3(CF.sub.2).sub.5C(O)CF.sub.3, CF.sub.3CF.sub.2C(O)CF.sub.2CF.sub.2CF.sub.3, CF.sub.3C(O)CF(CF.sub.3).sub.2.

  4. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  5. The Global Nitrogen Cycle

    Science.gov (United States)

    Galloway, J. N.

    2003-12-01

    Once upon a time nitrogen did not exist. Today it does. In the intervening time the universe was formed, nitrogen was created, the Earth came into existence, and its atmosphere and oceans were formed! In this analysis of the Earth's nitrogen cycle, I start with an overview of these important events relative to nitrogen and then move on to the more traditional analysis of the nitrogen cycle itself and the role of humans in its alteration.The universe is ˜15 Gyr old. Even after its formation, there was still a period when nitrogen did not exist. It took ˜300 thousand years after the big bang for the Universe to cool enough to create atoms; hydrogen and helium formed first. Nitrogen was formed in the stars through the process of nucleosynthesis. When a star's helium mass becomes great enough to reach the necessary pressure and temperature, helium begins to fuse into still heavier elements, including nitrogen.Approximately 10 Gyr elapsed before Earth was formed (˜4.5 Ga (billion years ago)) by the accumulation of pre-assembled materials in a multistage process. Assuming that N2 was the predominate nitrogen species in these materials and given that the temperature of space is -270 °C, N2 was probably a solid when the Earth was formed since its boiling point (b.p.) and melting point (m.p.) are -196 °C and -210 °C, respectively. Towards the end of the accumulation period, temperatures were probably high enough for significant melting of some of the accumulated material. The volcanic gases emitted by the resulting volcanism strongly influenced the surface environment. Nitrogen was converted from a solid to a gas and emitted as N2. Carbon and sulfur were probably emitted as CO and H2S (Holland, 1984). N2 is still the most common nitrogen volcanic gas emitted today at a rate of ˜2 TgN yr-1 (Jaffee, 1992).Once emitted, the gases either remained in the atmosphere or were deposited to the Earth's surface, thus continuing the process of biogeochemical cycling. The rate of

  6. Biomass Gasification Combined Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Judith A. Kieffer

    2000-07-01

    Gasification combined cycle continues to represent an important defining technology area for the forest products industry. The ''Forest Products Gasification Initiative'', organized under the Industry's Agenda 2020 technology vision and supported by the DOE ''Industries of the Future'' program, is well positioned to guide these technologies to commercial success within a five-to ten-year timeframe given supportive federal budgets and public policy. Commercial success will result in significant environmental and renewable energy goals that are shared by the Industry and the Nation. The Battelle/FERCO LIVG technology, which is the technology of choice for the application reported here, remains of high interest due to characteristics that make it well suited for integration with the infrastructure of a pulp production facility. The capital cost, operating economics and long-term demonstration of this technology area key input to future economically sustainable projects and must be verified by the 200 BDT/day demonstration facility currently operating in Burlington, Vermont. The New Bern application that was the initial objective of this project is not currently economically viable and will not be implemented at this time due to several changes at and around the mill which have occurred since the inception of the project in 1995. The analysis shows that for this technology, and likely other gasification technologies as well, the first few installations will require unique circumstances, or supportive public policies, or both to attract host sites and investors.

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

    Science.gov (United States)

    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

  8. Sunspot Cycle 24: Smallest Cycle in 100 Years?

    Science.gov (United States)

    2005-01-11

    and H. B. Hathaway, D. H., R. M. Wilson, and E. J. Reichmann (1994), The shape of Snodgrass (1988), The extended solar activity cycle, Nature, 333...748, the sunspot cycle, Sol. Phys., 151, 177. doi:10.1038/333748a0. Hathaway, D. H., R. M. Wilson, and E. J. Reichmann (2002), Group sun- spot numbers

  9. 'Benefits cycle' replacing premium cycle as consumerism takes hold.

    Science.gov (United States)

    2002-05-01

    The traditional premium cycle of ups and downs in rates is giving way to a new phenomenon--driven by the advent of consumerism in health care--termed the "benefits cycle" by one consultant. Rather than shifts in rates, he argues, the future will see shifts in benefits packages.

  10. Risk premia in general equilibrium

    DEFF Research Database (Denmark)

    Posch, Olaf

    This paper shows that non-linearities can generate time-varying and asymmetric risk premia over the business cycle. These (empirical) key features become relevant and asset market implications improve substantially when we allow for non-normalities in the form of rare disasters. We employ explicit...... solutions of dynamic stochastic general equilibrium models, including a novel solution with endogenous labor supply, to obtain closed-form expressions for the risk premium in production economies. We find that the curvature of the policy functions affects the risk premium through controlling the individual......'s effective risk aversion....

  11. North–South Distribution of Solar Flares during Cycle 23

    Indian Academy of Sciences (India)

    Bhuwan Joshi; P. Pant; P. K. Manoharan

    2006-06-01

    In this paper, we investigate the spatial distribution of solar flares in the northern and southern hemispheres of the Sun that occurred during the period 1996 to 2003. This period of investigation includes the ascending phase, the maximum and part of the descending phase of solar cycle 23. It is revealed that the flare activity during this cycle is low compared to the previous solar cycle, indicating the violation of Gnevyshev–Ohl rule. The distribution of flares with respect to heliographic latitudes shows a significant asymmetry between northern and southern hemisphere which is maximum during the minimum phase of the solar cycle. The present study indicates that the activity dominates the northern hemisphere in general during the rising phase of the cycle (1997–2000). The dominance of northern hemisphere shifted towards the southern hemisphere after the solar maximum in 2000 and remained there in the successive years. Although the annual variations in the asymmetry time series during cycle 23 are quite different from cycle 22, they are comparable to cycle 21.

  12. Mesozoic long-term eustatic cycles and their uncertain hierarchy

    Institute of Scientific and Technical Information of China (English)

    Dmitry A.Ruban

    2015-01-01

    Global sea-level has changed in a cyclic manner through geologic history, but the regularities of these changes are yet to be fully understood. Despite certain (and sometimes significant) differences, the available Mesozoic eustatic curves permit the outlining of long-term eustatic cycles, which are provi-sionally defined as cycles recognizable at the stage level and higher. Interpretation of the Triassic eustatic curves indicates two orders of long-term cycles and a 1st-order sea-level rise throughout the entire period. The Jurassic eustatic curves imply cyclicity of one or two orders, and a 1st-order eustatic rise during the entire period is also evident. Most challenges are interpretations for the Cretaceous; two to four orders of long-term eustatic cycles can be established for this period. Generally, the hierarchy of the long-term eustatic cycles might have changed through the Mesozoic. If so, and if one considers differ-ences of cycles of the same order between the periods of this era, it is difficult to apply “standard”hi-erarchical classifications to the documented cycles. The hypothetical uncertainty of the hierarchy of the Mesozoic long-term eustatic cycles is an important challenge for modern researchers.

  13. Operating regimes of signaling cycles: statics, dynamics, and noise filtering.

    Directory of Open Access Journals (Sweden)

    Carlos Gomez-Uribe

    2007-12-01

    Full Text Available A ubiquitous building block of signaling pathways is a cycle of covalent modification (e.g., phosphorylation and dephosphorylation in MAPK cascades. Our paper explores the kind of information processing and filtering that can be accomplished by this simple biochemical circuit. Signaling cycles are particularly known for exhibiting a highly sigmoidal (ultrasensitive input-output characteristic in a certain steady-state regime. Here, we systematically study the cycle's steady-state behavior and its response to time-varying stimuli. We demonstrate that the cycle can actually operate in four different regimes, each with its specific input-output characteristics. These results are obtained using the total quasi-steady-state approximation, which is more generally valid than the typically used Michaelis-Menten approximation for enzymatic reactions. We invoke experimental data that suggest the possibility of signaling cycles operating in one of the new regimes. We then consider the cycle's dynamic behavior, which has so far been relatively neglected. We demonstrate that the intrinsic architecture of the cycles makes them act--in all four regimes--as tunable low-pass filters, filtering out high-frequency fluctuations or noise in signals and environmental cues. Moreover, the cutoff frequency can be adjusted by the cell. Numerical simulations show that our analytical results hold well even for noise of large amplitude. We suggest that noise filtering and tunability make signaling cycles versatile components of more elaborate cell-signaling pathways.

  14. Life Cycle of Stars

    Science.gov (United States)

    1999-01-01

    In this stunning picture of the giant galactic nebula NGC 3603, the crisp resolution of NASA's Hubble Space Telescope captures various stages of the life cycle of stars in one single view. To the upper left of center is the evolved blue supergiant called Sher 25. The star has a unique circumstellar ring of glowing gas that is a galactic twin to the famous ring around the supernova 1987A. The grayish-bluish color of the ring and the bipolar outflows (blobs to the upper right and lower left of the star) indicates the presence of processed (chemically enriched) material. Near the center of the view is a so-called starburst cluster dominated by young, hot Wolf-Rayet stars and early O-type stars. A torrent of ionizing radiation and fast stellar winds from these massive stars has blown a large cavity around the cluster. The most spectacular evidence for the interaction of ionizing radiation with cold molecular-hydrogen cloud material are the giant gaseous pillars to the right of the cluster. These pillars are sculptured by the same physical processes as the famous pillars Hubble photographed in the M16 Eagle Nebula. Dark clouds at the upper right are so-called Bok globules, which are probably in an earlier stage of star formation. To the lower left of the cluster are two compact, tadpole-shaped emission nebulae. Similar structures were found by Hubble in Orion, and have been interpreted as gas and dust evaporation from possibly protoplanetary disks (proplyds). This true-color picture was taken on March 5, 1999 with the Wide Field Planetary Camera 2.

  15. MONITORED GEOLOGIC REPOSITORY LIFE CYCLE COST ESTIMATE ASSUMPTIONS DOCUMENT

    Energy Technology Data Exchange (ETDEWEB)

    R.E. Sweeney

    2001-02-08

    The purpose of this assumptions document is to provide general scope, strategy, technical basis, schedule and cost assumptions for the Monitored Geologic Repository (MGR) life cycle cost (LCC) estimate and schedule update incorporating information from the Viability Assessment (VA) , License Application Design Selection (LADS), 1999 Update to the Total System Life Cycle Cost (TSLCC) estimate and from other related and updated information. This document is intended to generally follow the assumptions outlined in the previous MGR cost estimates and as further prescribed by DOE guidance.

  16. Aspect of cumulative fatigue damage under multiaxial strain cycling.

    Science.gov (United States)

    Zamrik, S. Y.; Tang, P. Y.

    1972-01-01

    The concept of order of loading and its effect on cumulative fatigue damage under multiaxial strain cyclings was investigated. The effect is illustrated through nonlinear relationships between biaxial fatigue damage and cycle-ratio diagrams. Uniaxial theories such as Miner's method, the convergence method, and the double linear damage rule in its special and generalized form, were examined and extended to the biaxial case through the octahedral shear strain theory. The generalized double linear damage rule was found more applicable to biaxial cumulative fatigue damage.

  17. 40 CFR 86.1601 - General applicability.

    Science.gov (United States)

    2010-07-01

    ... Performance Adjustments for New and In-Use Motor Vehicles and Engines § 86.1601 General applicability. This subpart applies to manufacturers of motor vehicles and motor vehicle engines (hereafter referred to as... manufacturers certifying new light-duty vehicles, light-duty trucks, and Otto-cycle complete heavy-duty...

  18. Unemployment Duration over the Business Cycle

    DEFF Research Database (Denmark)

    Rosholm, Michael

    1996-01-01

    In this paper I study the way in which individual unemployment durations vary over the business cycle, as measured by the aggregate unemployment rate. I decompose the cyclical variations in observed unemployment durations into a composition al and a general part. The compositional part consists...... of variations in observed as well as unobserved average individual-specific heterogeneity amongst those flowing into unemployment. The main finding is that the major part (but not all) of the variations in unemployment durations is caused by variations in macroeconomic conditions (i.e. in the aggregate...... unemployment rate) rathan than by changes in the composition of those becoming unemployed....

  19. An introduction to closed cycle cryogenic coolers

    Science.gov (United States)

    Chellis, F. F.

    1980-01-01

    Closed cycle cryogenic coolers are used extensively for cooling infrared detectors and other specialized electronic devices. Because of the special requirements of each electro-optical system it is generally necessary to custom design the cryocooler to fit the requirements. Early and close cooperation between the electro-optical systems designer and the cryocooler manufacturer is important to the successful marriage of the cryocooler with the total electro-optical system. Limitations of various cryocooling techniques are presented, and consideration for cryocooling integration are addressed.

  20. Activity Cycle of Solar Filaments

    Indian Academy of Sciences (India)

    K. J. Li; Q. X. Li; P. X. Gao; J. Mu; H. D. Chen; T. W. Su

    2007-06-01

    Long-term variation in the distribution of the solar filaments observed at the Observatorie de Paris, Section de Meudon from March 1919 to December 1989 is presented to compare with sunspot cycle and to study the periodicity in the filament activity, namely the periods of the coronal activity with the Morlet wavelet used. It is inferred that the activity cycle of solar filaments should have the same cycle length as sunspot cycle, but the cycle behavior of solar filaments is globally similar in profile with, but different in detail from, that of sunspot cycles. The amplitude of solar magnetic activity should not keep in phase with the complexity of solar magnetic activity. The possible periods in the filament activity are about 10.44 and 19.20 years. The wavelet local power spectrum of the period 10.44 years is statistically significant during the whole consideration time. The wavelet local power spectrum of the period 19.20 years is under the 95% confidence spectrum during the whole consideration time, but over the mean red-noise spectrum of = 0.72 before approximate Carrington rotation number 1500, and after that the filament activity does not statistically show the period. Wavelet reconstruction indicates that the early data of the filament archive (in and before cycle 16) are more noiseful than the later (in and after cycle 17).

  1. Variations on the Zilch Cycle

    Science.gov (United States)

    Binder, P.-M.; Tanoue, C. K. S.

    2013-01-01

    Thermo dynamic cycles in introductory physics courses are usually made up from a small number of permutations of isothermal, adiabatic, and constant-pressure and volume quasistatic strokes, with the working fluid usually being an ideal gas. Among them we find the Carnot, Stirling, Otto, Diesel, and Joule-Brayton cycles; in more advanced courses,…

  2. Economic growth and business cycles

    NARCIS (Netherlands)

    Canton, E.J.F.

    1997-01-01

    This thesis contains five essays on economic growth and business cycles. The main focus is on the interaction between economic growth and the cycle: is cyclical variability good or bad for the long-run rate of economic growth? The introduction aims to provide some empirical evidence for an

  3. The LifeCycle model

    DEFF Research Database (Denmark)

    Krink, Thiemo; Løvbjerg, Morten

    2002-01-01

    Adaptive search heuristics are known to be valuable in approximating solutions to hard search problems. However, these techniques are problem dependent. Inspired by the idea of life cycle stages found in nature, we introduce a hybrid approach called the LifeCycle model that simultaneously applies...

  4. Drought and ecosystem carbon cycling

    NARCIS (Netherlands)

    Molen, van der M.K.; Dolman, A.J.; Ciais, P.; Eglin, T.; Gobron, N.; Law, B.E.; Meir, P.; Peters, W.; Philips, O.L.; Hurk, van den B.J.J.M.; Jeu, M.; Kruijt, B.; Teuling, A.J.; Werf, van der G.R.; Wang, G.

    2011-01-01

    Drought as an intermittent disturbance of the water cycle interacts with the carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequ

  5. Life Cycle of a Pencil.

    Science.gov (United States)

    Reeske, Mike

    2000-01-01

    Explains a project called "Life Cycle of a Pencil" which was developed by the National Science Teachers Association (NSTA) and the U.S. Environmental Protection Agency (USEPA). Describes the life cycle of a pencil in stages starting from the first stage of design to the sixth stage of product disposal. (YDS)

  6. Emissions from photovoltaic life cycles

    NARCIS (Netherlands)

    Fthenakis, V.M.; Kim, H.C.; Alsema, E.A.

    2008-01-01

    Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004–2006, this study presents the life-cycle greenhou

  7. The LifeCycle model

    DEFF Research Database (Denmark)

    Krink, Thiemo; Løvbjerg, Morten

    2002-01-01

    Adaptive search heuristics are known to be valuable in approximating solutions to hard search problems. However, these techniques are problem dependent. Inspired by the idea of life cycle stages found in nature, we introduce a hybrid approach called the LifeCycle model that simultaneously applies...

  8. Economic growth and business cycles

    NARCIS (Netherlands)

    Canton, E.J.F.

    1997-01-01

    This thesis contains five essays on economic growth and business cycles. The main focus is on the interaction between economic growth and the cycle: is cyclical variability good or bad for the long-run rate of economic growth? The introduction aims to provide some empirical evidence for an investmen

  9. Comparison of the regulated air pollutant emission characteristics of real-world driving cycle and ECE cycle for motorcycles

    Science.gov (United States)

    Chiang, Hung-Lung; Huang, Pei-Hsiu; Lai, Yen-Ming; Lee, Ting-Yi

    2014-04-01

    Motorcycles are an important means of transportation, and their numbers have increased significantly in recent years. However, motorcycles can emit significant amounts of air pollutants; therefore, the emission characteristics and driving patterns of motorcycles are necessary baseline information for the implementation of control measures for motorcycles in urban areas. The selected motorcycles were equipped with global positioning systems (GPS) to obtain speed-time data for determination of the characteristics of real-world driving parameters, and an on-board exhaust gas analyser with data logger was employed to determine the instantaneous concentration of regulated air pollutants from motorcycle exhaust. Results indicated that the time proportions of acceleration, cruising, and deceleration are different from those of the Economic Commission for Europe (ECE) driving cycle, and the time percentages of acceleration and deceleration of the ECE cycle are much less than those in Taichung city. In general, the emission factors of the Taichung motorcycle driving cycle (TMDC) were higher HC and lower NOx emission than those of the ECE cycle. The average fuel consumption of tested motorcycles on three roads during workdays was 5% higher than that on weekends. The fuel consumption in the real-world motorcycle driving cycle was also about 7% higher than that of the ECE cycle, which again indicates that the ECE cycle is unsuitable for measuring fuel consumption in the Taichung metropolitan area. Therefore, understanding the local driving cycle is necessary for developing accurate emission data for air pollution control measures for urban areas.

  10. Longitudinal study of insulin resistance and sex hormones over the menstrual cycle: the BioCycle Study.

    Science.gov (United States)

    Yeung, Edwina H; Zhang, Cuilin; Mumford, Sunni L; Ye, Aijun; Trevisan, Maurizio; Chen, Liwei; Browne, Richard W; Wactawski-Wende, Jean; Schisterman, Enrique F

    2010-12-01

    Conflicting findings have been reported regarding the effect of menstrual cycle phase and sex hormones on insulin sensitivity. The aim was to determine the pattern of insulin resistance over the menstrual cycle and whether variations in sex hormones explain these patterns. The BioCycle study is a longitudinal study that measured hormones at different phases of the menstrual cycle. Participants had up to eight visits per cycle; each visit was timed using fertility monitors to capture sensitive windows of hormonal changes. The study was conducted in the general community of the University at Buffalo (Buffalo, NY). A total of 257 healthy, premenopausal women (age, 27±8 yr; body mass index, 24±4 kg/m2) participated in the study. We measured fasting insulin, glucose, and insulin resistance by the homeostasis model of insulin resistance (HOMA-IR). Significant changes in HOMA-IR were observed over the menstrual cycle; from a midfollicular phase level of 1.35, levels rose to 1.59 during the early luteal phase and decreased to 1.55 in the late-luteal phase. HOMA-IR levels primarily reflected changes in insulin and not glucose. After adjustment for age, race, cycle, and other sex hormones, HOMA-IR was positively associated with estradiol (β=0.082; Pmenstrual cycle variability. Estradiol and progesterone were positively associated with insulin resistance and should be considered in studies of insulin resistance among premenopausal women.

  11. Prospects for Predicting Cycle 24

    Indian Academy of Sciences (India)

    Arnab Rai Choudhuri

    2008-03-01

    Although we have reliable data of solar polar fields only from the mid-1970s, it seems that the polar field at a minimum is well correlated with the next cycle, but the strength of the cycle is not correlated with the polar field produced at its end. We explain this by suggesting that the Babcock–Leighton mechanism of poloidal field generation from tilted active regions involves randomness, whereas the other aspects of the dynamo process are more ordered. To model actual cycles, we have to ‘correct’ our theoretical dynamo model by ‘feeding’ information about the polar field at the minima. Following this process, we find that our model fits the observed sunspot numbers of cycles 21–23 reasonably well and predicts that cycle 24 will be the weakest in a century.

  12. Limit cycles in quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, Patrick

    2015-04-27

    In this thesis we investigate Limit Cycles in Quantum Systems. Limit cycles are a renormalization group (RG) topology. When degrees of freedom are integrated out, the coupling constants flow periodically in a closed curve. The presence of limit cycles is restricted by the necessary condition of discrete scale invariance. A signature of discrete scale invariance and limit cycles is log-periodic behavior. The first part of this thesis is concerned with the study of limit cycles with the similarity renormalization group (SRG). Limit cycles are mainly investigated within conventional renormalization group frameworks, where degrees of freedom, which are larger than a given cutoff, are integrated out. In contrast, in the SRG potentials are unitarily transformed and thereby obtain a band-diagonal structure. The width of the band structure can be regarded as an effective cutoff. We investigate the appearance of limit cycles in the SRG evolution. Our aim is to extract signatures as well as the scaling factor of the limit cycle. We consider the 1/R{sup 2}-potential in a two-body system and a three-body system with large scattering lengths. Both systems display a limit cycle. Besides the frequently used kinetic energy generator we apply the exponential and the inverse generator. In the second part of this thesis, Limit Cycles at Finite Density, we examine the pole structure of the scattering amplitude for distinguishable fermions at zero temperature in the medium. Unequal masses and a filled Fermi sphere for each fermion species are considered. We focus on negative scattering lengths and the unitary limit. The properties of the three-body spectrum in the medium and implications for the phase structure of ultracold Fermi gases are discussed.

  13. Evaluation method for regional water cycle health based on nature-society water cycle theory

    Science.gov (United States)

    Zhang, Shanghong; Fan, Weiwei; Yi, Yujun; Zhao, Yong; Liu, Jiahong

    2017-08-01

    Regional water cycles increasingly reflect the dual influences of natural and social processes, and are affected by global climate change and expanding human activities. Understanding how to maintain a healthy state of the water cycle has become an important proposition for sustainable development of human society. In this paper, natural-social attributes of the water cycle are synthesized and 19 evaluation indices are selected from four dimensions, i.e., water-based ecosystem integrity, water quality, water resource abundance and water resource use. A hierarchical water-cycle health evaluation system is established. An analytic hierarchy process is used to set the weight of the criteria layer and index layer, and the health threshold for each index is defined. Finally, a water-cycle health composite-index assessment model and fuzzy recognition model are constructed based on the comprehensive index method and fuzzy mathematics theory. The model is used to evaluate the state of health of the water cycle in Beijing during 2010-2014 and in the planning year (late 2014), considering the transfer of 1 billion m3 of water by the South-to-North Water Diversion Project (SNWDP). The results show health scores for Beijing of 2.87, 3.10, 3.38, 3.11 and 3.02 during 2010-2014. The results of fuzzy recognition show that the sub-healthy grade accounted for 54%, 49%, 61% and 49% of the total score, and all years had a sub-healthy state. Results of the criteria layer analysis show that water ecosystem function, water quality and water use were all at the sub-healthy level and that water abundance was at the lowest, or sick, level. With the water transfer from the SNWDP, the health score of the water cycle in Beijing reached 4.04. The healthy grade accounted for 60% of the total score, and the water cycle system was generally in a healthy state. Beijing's water cycle health level is expected to further improve with increasing water diversion from the SNWDP and industrial

  14. Uncertainty in Life Cycle Assessment of Nanomaterials

    Science.gov (United States)

    Seager, T. P.; Linkov, I.

    Despite concerns regarding environmental fate and toxicology, engineered nanostructured material manufacturing is expanding at an increasingly rapid pace. In particular, the unique properties of single walled carbon nanotubes (SWCNT) have made them attractive in many areas, including high-tech power applications such as experimental batteries, fuel cells or electrical wiring. The intensity of research interest in SWCNT has raised questions regarding the life cycle environmental impact of nanotechnologies, including assessment of: worker and consumer safety, greenhouse gas emissions, toxicological risks associated with production or product emissions and the disposition of nanoproducts at end of life. However, development of appropriate nanotechnology assessment tools has lagged progress in the nanotechnologies themselves. In particular, current approaches to life cycle assessment (LCA) — originally developed for application in mature manufacturing industries such as automobiles and chemicals — suffer from several shortcomings that make applicability to nanotechnologies problematic. Among these are uncertainties related to the variability of material properties, toxicity and risk, technology performance in the use phase, nanomaterial degradation and change during the product life cycle and the impact assessment stage of LCA. This chapter expounds upon the unique challenges presented by nanomaterials in general, specifies sources of uncertainty and variability in LCA of SWCNT for use in electric and hybrid vehicle batteries and makes recommendations for modeling and decision-making using LCA in a multi-criteria decision analysis framework under conditions of high uncertainty.1

  15. Cycle chemistry in cycles with drum boilers: Is there a niche for the use of alternative organic chemicals in the continuum of treatments?

    Energy Technology Data Exchange (ETDEWEB)

    Bursik, A. [University of Stuttgart (Germany); Bezzoli, P.; Graf, A.

    2003-06-01

    Organic cycle additives, particularly amines, have been used for many years in both industrial steam and power generation. The extent of the application of amine treatments in classic fossil utility power plants is steadily increasing. The use of amines is reported even from relatively new combined cycles, too. So far, none of the acknowledged plant cycle chemistry guidelines have included or discussed this type of cycle treatment. This means that neither the current nor the potential users have adequate guidance on hand. For this reason, in addition to good and approved organic cycle additives, some inadequate products are still on the market. This paper discusses the behavior of organics in the plant cycle in general and focuses on the possible application of amines for the cycle treatment. The pros and cons of their application are considered. The possibility of including the amine treatment in the continuum of treatment is discussed. (orig.)

  16. Life cycle of mobile devices

    Directory of Open Access Journals (Sweden)

    T.V. Rohal

    2011-12-01

    Full Text Available Article is devoted features of life cycle of mobile devices. The article highlighted a number of disadvantages associated with managing the life cycle of the product. Disadvantages include the orientation is not on the quality of mobile devices and their design, the obsolescence of digital products. The article drew attention to the need for process improvement life cycle management of mobile devices. For since this type of product is now the most popular among the population, consumers are interested, first of all, quality, and only then, look good.

  17. Menstrual cycle and skin reactivity

    DEFF Research Database (Denmark)

    Agner, T; Damm, P; Skouby, S O

    1991-01-01

    The hypothesis was tested that a cyclic variation exists in skin reactivity to irritant stimuli. Twenty-nine healthy women with regular menstrual cycles were challenged with sodium lauryl sulfate as an irritant patch test at day 1 and at days 9 through 11 of the menstrual cycle. The skin response...... in the menstrual cycle as evaluated by visual scoring (p less than 0.05) as well as by measurement of transepidermal water loss (p less than 0.05) and edema formation (p less than 0.005)....

  18. Digital daily cycles of individuals

    DEFF Research Database (Denmark)

    Aledavood, Talayeh; Jørgensen, Sune Lehmann; Saramäki, Jari

    2015-01-01

    Humans, like almost all animals, are phase-locked to the diurnal cycle. Most of us sleep at night and are active through the day. Because we have evolved to function with this cycle, the circadian rhythm is deeply ingrained and even detectable at the biochemical level. However, within the broader...... day-night pattern, there are individual differences: e.g., some of us are intrinsically morning-active, while others prefer evenings. In this article, we look at digital daily cycles: circadian patterns of activity viewed through the lens of auto-recorded data of communication and online activity. We...

  19. Introducing Life Cycle Impact Assessment

    DEFF Research Database (Denmark)

    Hauschild, Michael Zwicky; Huijbregts, Mark AJ

    2015-01-01

    methodology projects and presents the international scientific discussions and methodological consensus attempts in consecutive working groups under the auspices of the Society of Environmental Toxicology and Chemistry (SETAC) as well as the UNEP/ SETAC Life Cycle Initiative, and the (almost) parallel......This chapter serves as an introduction to the presentation of the many aspects of life cycle impact assessment (LCIA) in this volume of the book series ‘LCA Compendium’. It starts with a brief historical overview of the development of life cycle impact assessment driven by numerous national LCIA...

  20. Life-cycle cost analysis of adsorption cycles for desalination

    KAUST Repository

    Thu, Kyaw

    2010-08-01

    This paper presents the thermo-economic analysis of the adsorption desalination (AD) cycle that is driven by low-temperature waste heat from exhaust of industrial processes or renewable sources. The AD cycle uses an adsorbent such as the silica gel to desalt the sea or brackish water. Based on an experimental prototype AD plant, the life-cycle cost analysis of AD plants of assorted water production capacities has been simulated and these predictions are translated into unit cost of water production. Our results show that the specific energy consumption of the AD cycle is 1.38 kWh/m3 which is the lowest ever reported. For a plant capacity of 1000 m3/d, the AD cycle offers a unit cost of $0.457/m3 as compared to more than $0.9 for the average RO plants. Besides being cost-effective, the AD cycle is also environment-friendly as it emits less CO2 emission per m3 generated, typically 85% less, by comparison to an RO process. © 2010 Desalination Publications.

  1. Water cycle investigations in Hungarian forest ecosystems

    Institute of Scientific and Technical Information of China (English)

    Judit Sitkey

    2006-01-01

    From the biological point of view the value of autotrophy plant association is determined by the carbon fixation and the carbon cycle. Among the plant associations of Hungary, forest has the largest biological carbon fixation and carbon cycle. In general,the annual water cycle is the key factor in the organic material production of the Hungarian forests. The most intensive water consumption and organic material production take place from May till July, which period is named main water consumption and respectively main growing period. In Hungary the categories of the forest climate are characterized by main tree species and based on the forest climate covers 8% of the forest area, hornbeam-oak forest climate covers 22%, sessile oak-Turkey oak forest climate covers48% and forest steppe climate covers 22%. Partly in the frame of ICP-Forests, the Department of Ecology in the Forest Research Institute carries out long term, complex ecophysiological investigations on several sample plots (so-called basic plots) throughout the whole country. The organic material production (growth), the nutrient and water cycle, the measurements of air pollutants and meteorological parameters, as well as chemical analyses are all part of the investigations. As a comparison the figure of two basic plotsforest steppe climate in the hydrological year of 2001-2002. In the Hungarian forest 60%-70% of the precipitation is used for interception, evaporation, and in the vegetation season, for the transpiration both in beech and forest steppe climate. From other point of view, only 30%-40% of the open air precipitation infiltrates into the soil and can be utilized by the forest.

  2. Constraining duty cycles through a Bayesian technique

    CERN Document Server

    Romano, P; Segreto, A; Ducci, L; Vercellone, S

    2014-01-01

    The duty cycle (DC) of astrophysical sources is generally defined as the fraction of time during which the sources are active. However, DCs are generally not provided with statistical uncertainties, since the standard approach is to perform Monte Carlo bootstrap simulations to evaluate them, which can be quite time consuming for a large sample of sources. As an alternative, considerably less time-consuming approach, we derived the theoretical expectation value for the DC and its error for sources whose state is one of two possible, mutually exclusive states, inactive (off) or flaring (on), as based on a finite set of independent observational data points. Following a Bayesian approach, we derived the analytical expression for the posterior, the conjugated distribution adopted as prior, and the expectation value and variance. We applied our method to the specific case of the inactivity duty cycle (IDC) for supergiant fast X-ray transients. We also studied IDC as a function of the number of observations in the ...

  3. Life cycle human health impacts of 875 pesticides

    DEFF Research Database (Denmark)

    Fantke, Peter; Jolliet, Oliver

    2016-01-01

    Purpose Residues in field crops grown and harvested for human consumption are the main contributor to overall human exposure toward agricultural pesticides for the general population. However, exposure from crop residues is currently not considered in life cycle assessment practice. We therefore...... present a consistent framework for characterizing human toxicological impacts associated with pesticides applied to agricultural crops in the frame of life cycle impact assessment based on state-of-the-art data and methods. Methods We combine a dynamic multicrop plant uptake model designed for evaluating......-crop combinations of 10 orders of magnitude. Conclusions Our framework is operational for use in current life cycle impact assessment models, is made available for USEtox, and closes an important gap in the assessment of human exposure to pesticides. For ready use in life cycle assessment studies, we present...

  4. Criteria for robustness of heteroclinic cycles in neural microcircuits

    Science.gov (United States)

    2011-01-01

    We introduce a test for robustness of heteroclinic cycles that appear in neural microcircuits modeled as coupled dynamical cells. Robust heteroclinic cycles (RHCs) can appear as robust attractors in Lotka-Volterra-type winnerless competition (WLC) models as well as in more general coupled and/or symmetric systems. It has been previously suggested that RHCs may be relevant to a range of neural activities, from encoding and binding to spatio-temporal sequence generation. The robustness or otherwise of such cycles depends both on the coupling structure and the internal structure of the neurons. We verify that robust heteroclinic cycles can appear in systems of three identical cells, but only if we require perturbations to preserve some invariant subspaces for the individual cells. On the other hand, heteroclinic attractors can appear robustly in systems of four or more identical cells for some symmetric coupling patterns, without restriction on the internal dynamics of the cells. PMID:22656192

  5. Prediction of Sunspot Cycles by Data Assimilation Method

    CERN Document Server

    Kitiashvili, I N

    2008-01-01

    Despite the known general properties of the solar cycles, a reliable the forecast of the 11-year sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to cycle and by the influence of variations of turbulent dynamo processes, which are far from understanding. For predicting the solar cycle properties we make an initial attempt to use the Ensemble Kalman Filter (EnKF), a data assimilation method, which takes into account uncertainties of a dynamo model and measurements, and allows to estimate future observational data. We present the results of forecasting the solar cycles obtained by the EnKF method in application to a low-mode nonlinear dynamical system, modeling the solar alpha-Omega dynamo process with variable magnetic helicity. Calculations of the predictions for previous sunspot cycles show good agreement (with error 10%) with actual data. This forecast model predicts that the next sunspot cycle will be significant by...

  6. Thermal cycling can extend tool life in orthopaedic operating rooms.

    Science.gov (United States)

    Katchky, Ryan N; McLachlin, Stewart D; Wong, Edwin K Y; Finkelstein, Joel; Kreder, Hans J; Whyne, Cari M

    2016-03-01

    Thermal cycling is a temperature modulation process developed to improve the performance, durability and longevity of materials. This process has been successfully utilized in the automotive, aeronautic and manufacturing industries. Surgical cutting tools undergo cyclical loading and generally fail by dulling, suggesting that thermal cycling may improve their performance and longevity. Ten 2.5 mm orthopaedic drill bits were randomized, with five undergoing thermal cycling within their sterile packaging and five serving as untreated controls. Using a servohydraulic testing machine, 100 drilling cycles were performed with each drill bit into the diaphyseal region of bovine femurs. After every 25 cycles, data was collected by performing identical drilling cycles into simulated human cortical bone material. Maximum force, maximum normalized torque and drilling work were measured, and a scanning electron microscope was used to measure outer corner wear. After 100 drilling cycles, the maximum drilling force, maximum normalized torque, drilling work and microscopic outer corner wear were all significantly lower for the treated drill bits (p cutting tools. Application of this technology may also be relevant to surgical cutting tools such as saw blades, burrs and reamers.

  7. Cycle Average Peak Fuel Temperature Prediction Using CAPP/GAMMA+

    Energy Technology Data Exchange (ETDEWEB)

    Tak, Nam-il; Lee, Hyun Chul; Lim, Hong Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In order to obtain a cycle average maximum fuel temperature without rigorous efforts, a neutronics/thermo-fluid coupled calculation is needed with depletion capability. Recently, a CAPP/GAMMA+ coupled code system has been developed and the initial core of PMR200 was analyzed using the CAPP/GAMMA+ code system. The GAMMA+ code is a system thermo-fluid analysis code and the CAPP code is a neutronics code. The General Atomics proposed that the design limit of the fuel temperature under normal operating conditions should be a cycle-averaged maximum value. Nonetheless, the existing works of Korea Atomic Energy Research Institute (KAERI) only calculated the maximum fuel temperature at a fixed time point, e.g., the beginning of cycle (BOC) just because the calculation capability was not ready for a cycle average value. In this work, a cycle average maximum fuel temperature has been calculated using CAPP/GAMMA+ code system for the equilibrium core of PMR200. The CAPP/GAMMA+ coupled calculation was carried out for the equilibrium core of PMR 200 from BOC to EOC to obtain a cycle average peak fuel temperature. The peak fuel temperature was predicted to be 1372 .deg. C near MOC. However, the cycle average peak fuel temperature was calculated as 1181 .deg. C, which is below the design target of 1250 .deg. C.

  8. Systems Analyses of Advanced Brayton Cycles

    Energy Technology Data Exchange (ETDEWEB)

    A.D. Rao; D.J. Francuz; J.D. Maclay; J. Brouwer; A. Verma; M. Li; G.S. Samuelsen

    2008-09-30

    The main objective is to identify and assess advanced improvements to the Brayton Cycle (such as but not limited to firing temperature, pressure ratio, combustion techniques, intercooling, fuel or combustion air augmentation, enhanced blade cooling schemes) that will lead to significant performance improvements in coal based power systems. This assessment is conducted in the context of conceptual design studies (systems studies) that advance state-of-art Brayton cycles and result in coal based efficiencies equivalent to 65% + on natural gas basis (LHV), or approximately an 8% reduction in heat rate of an IGCC plant utilizing the H class steam cooled gas turbine. H class gas turbines are commercially offered by General Electric and Mitsubishi for natural gas based combined cycle applications with 60% efficiency (LHV) and it is expected that such machine will be offered for syngas applications within the next 10 years. The studies are being sufficiently detailed so that third parties will be able to validate portions or all of the studies. The designs and system studies are based on plants for near zero emissions (including CO{sub 2}). Also included in this program is the performance evaluation of other advanced technologies such as advanced compression concepts and the fuel cell based combined cycle. The objective of the fuel cell based combined cycle task is to identify the desired performance characteristics and design basis for a gas turbine that will be integrated with an SOFC in Integrated Gasification Fuel Cell (IGFC) applications. The goal is the conceptualization of near zero emission (including CO{sub 2} capture) integrated gasification power plants producing electricity as the principle product. The capability of such plants to coproduce H{sub 2} is qualitatively addressed. Since a total systems solution is critical to establishing a plant configuration worthy of a comprehensive market interest, a baseline IGCC plant scheme is developed and used to study

  9. Carnot cycle at finite power: attainability of maximal efficiency.

    Science.gov (United States)

    Allahverdyan, Armen E; Hovhannisyan, Karen V; Melkikh, Alexey V; Gevorkian, Sasun G

    2013-08-01

    We want to understand whether and to what extent the maximal (Carnot) efficiency for heat engines can be reached at a finite power. To this end we generalize the Carnot cycle so that it is not restricted to slow processes. We show that for realistic (i.e., not purposefully designed) engine-bath interactions, the work-optimal engine performing the generalized cycle close to the maximal efficiency has a long cycle time and hence vanishing power. This aspect is shown to relate to the theory of computational complexity. A physical manifestation of the same effect is Levinthal's paradox in the protein folding problem. The resolution of this paradox for realistic proteins allows to construct engines that can extract at a finite power 40% of the maximally possible work reaching 90% of the maximal efficiency. For purposefully designed engine-bath interactions, the Carnot efficiency is achievable at a large power.

  10. Towards Life Cycle Sustainability Assessment

    Directory of Open Access Journals (Sweden)

    Marzia Traverso

    2010-10-01

    Full Text Available Sustainability is nowadays accepted by all stakeholders as a guiding principle for both public policy making and corporate strategies. However, the biggest challenge for most organizations remains in the real and substantial implementation of the sustainability concept. The core of the implementation challenge is the question, how sustainability performance can be measured, especially for products and processes. This paper explores the current status of Life Cycle Sustainability Assessment (LCSA for products and processes. For the environmental dimension well established tools like Life Cycle Assessment are available. For the economic and social dimension, there is still need for consistent and robust indicators and methods. In addition to measuring the individual sustainability dimensions, another challenge is a comprehensive, yet understandable presentation of the results. The “Life Cycle Sustainability Dashboard” and the “Life Cycle Sustainability Triangle” are presented as examples for communication tools for both experts and non expert stakeholders.

  11. Revenue cycle management, Part II.

    Science.gov (United States)

    Crew, Matt

    2007-01-01

    The proper management of your revenue cycle requires the application of "best practices" and the continual monitoring and measuring of the entire cycle. The correct technology will enable you to gain the insight and efficiencies needed in the ever-changing healthcare economy. The revenue cycle is a process that begins when you negotiate payor contracts, set fees, and schedule appointments and continues until claims are paid in full. Every single step in the cycle carries equal importance. Monitoring all phases and a commitment to continually communicating the results will allow you to achieve unparalleled success. In part I of this article, we explored the importance of contracting, scheduling, and case management as well as coding and clinical documentation. We will now take a closer look at the benefits charge capture, claim submission, payment posting, accounts receivable follow-up, and reporting can mean to your practice.

  12. (Auto)Ethnographies and Cycling

    DEFF Research Database (Denmark)

    Larsen, Jonas

    2014-01-01

    , habits and affective capacities of cycling are cultivated and performed. The article argues that autoethnography is particularly apt at illuminating the embodied qualities of movement, and it sits within established ethnographies of ‘excising’ and ‘mobile bodies’. In the second part of the article, I......This article discusses the formation, salience and reformation of everyday bodily routines and resources in relation to cycling; it also examines how we can study them ethnographically in different places. I discuss forms of embodied, sensuous and mobile ethnography that can illuminate how routines...... draw upon ongoing autoethnographies of cycling in a familiar place (my hometown, Copenhagen) and by learning to cycle ‘out-of-place’ (in London) and ‘in-a-new–way’ (when commuting long distance on a racer bike). The study challenges static notions of the body by analysing how cyclists’ (and researchers...

  13. Air Quality Management Process Cycle

    Science.gov (United States)

    Air quality management are activities a regulatory authority undertakes to protect human health and the environment from the harmful effects of air pollution. The process of managing air quality can be illustrated as a cycle of inter-related elements.

  14. Total Product Life Cycle (TPLC)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Total Product Life Cycle (TPLC) database integrates premarket and postmarket data about medical devices. It includes information pulled from CDRH databases...

  15. Studies on the Life Cycle

    African Journals Online (AJOL)

    The life cycle of the honeybee, Apis mellifera adansonii, was studied in mangrove area by monitoring the developmental .... honey, beeswax and other bee products (Malaka and Fasasi, 2005 .... decline of castes in the affected colony, thereby.

  16. Mirador - Carbon Cycle and Ecosystems

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. This Focus Area deals with the cycling of carbon in reservoirs and ecosystems as it changes naturally, is changed by humans,...

  17. Endogenous, Imperfectly Competitive Business Cycles

    DEFF Research Database (Denmark)

    Whitta-Jacobsen, Hans Jørgen

    by monopolistic competition. An implicit assumption of barriers to entry justifies that the number of firms is fixed even when positive profits occur. It turns out that both market power of firms on the product markets and market power of unions on the labor markets make the occurrence of cycles more likely......We investigate how imperfect competition affects the occurrence and the properties of endogenous, rational expectations business cycles in an overlapping generations model with constant returns to scale in production. The model has explicit product and labor markets all characterized....... In particular, imperfect competition on the product markets and the positive profits associated with it may have the effect that there is a cycle even if the labor supply curve is increasing in the real-wage rate. For competitive cycles is required not only a decreasing labor supply curve, but a wage elasticity...

  18. Venus Altitude Cycling Balloon Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The ISTAR Group ( IG) and team mate Thin Red Line Aerospace (TRLA) propose a Venus altitude cycling balloon (Venus ACB), an innovative superpressure balloon...

  19. National Urea Cycle Disorders Foundation

    Science.gov (United States)

    ... triggers undiagnosed fatal urea cycle disorder in Tennessee wife and teacher. Story . More information about bariatric surgery ... with sodium phenylbutyrate may decrease liver dysfunction in patients with ASA. Details "IN TRIBUTE TO HER SON, ...

  20. Total Product Life Cycle (TPLC)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Total Product Life Cycle (TPLC) database integrates premarket and postmarket data about medical devices. It includes information pulled from CDRH databases...

  1. Corporate governance cycles during transition

    DEFF Research Database (Denmark)

    Mygind, Niels; Demina, Natalia; Gregoric, Aleksandra

    2004-01-01

    -nancial system. To provide simple hypothesis tests, we use Russian enterprise data for 1995-2003 and Slovenian data covering 1998-2003. In spite of differences in institutional development, con-cerning privatization and development of corporate governance institutions, we find that govern-ance cycles are broadly......Ownership is determined by firm specific factors and the environment. Firms change over their life-cycle. The governance cycle - here defined as changes in identity of the dominant owner and own-ership concentration - is marked by key phases including start-up, growth, and possibly a restructur...... of ownership on managers, external domestic and foreign owners. JEL-codes: G3, J5, P2, P3 - Keywords: corporate governance, life-cycle, privatization, ownership change, transition economies, Russia and Slovenia....

  2. Life Cycle Costing: An Introduction

    DEFF Research Database (Denmark)

    Rödger, Jan-Markus; Kjær, Louise Laumann; Pagoropoulos, Aris

    2018-01-01

    The chapter gives an introduction to life cycle costing (LCC) and how it can be used to support decision-making. It can form the economic pillar in a full life cycle sustainability assessment, but often system delimitations differ depending on the goal and scope of the study. To provide a profound...... Life Cycle Assessment (LCA) in terms of system delimitation. Differences are explained and addressed, and an overview is given of the main cost categories to consider from different user perspectives. As inventory data is often sensitive in financial analyses, a list of relevant databases is provided...... understanding this chapter describes several approaches and terms, fundamental principles and different types of costs. A brief introduction is given to conventional LCC and societal LCC but the main focus is on environmental Life Cycle Costing (eLCC) as the LCC approach that is compatible with environmental...

  3. General Nuclear Medicine

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z General Nuclear Medicine Nuclear medicine imaging uses small amounts of ... limitations of General Nuclear Medicine? What is General Nuclear Medicine? Nuclear medicine is a branch of medical ...

  4. General Ultrasound Imaging

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z General Ultrasound Ultrasound imaging uses sound waves to produce pictures ... limitations of General Ultrasound Imaging? What is General Ultrasound Imaging? Ultrasound is safe and painless, and produces ...

  5. Calfornia General Plans Rural

    Data.gov (United States)

    California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...

  6. Calfornia General Plans

    Data.gov (United States)

    California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...

  7. Calfornia General Plans

    Data.gov (United States)

    California Department of Resources — We undertook creating the first ever seamless statewide General Plan map for California. All county general plans and many city general plans were integrated into 1...

  8. On acyclicity of games with cycles

    DEFF Research Database (Denmark)

    Andersson, Klas Olof Daniel; Hansen, Thomas Dueholm; Gurvich, Vladimir

    2010-01-01

    We study restricted improvement cycles (ri-cycles) in finite positional n-person games with perfect information modeled by directed graphs (di-graphs) that may contain directed cycles (di-cycles). We assume that all these di-cycles form one outcome c, for example, a draw. We obtain criteria of re...

  9. Detonation Jet Engine. Part 1--Thermodynamic Cycle

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. The efficiency advantages of thermodynamic detonative combustion cycle over Humphrey combustion cycle at constant volume and Brayton combustion cycle at constant pressure were demonstrated. An ideal Ficket-Jacobs detonation cycle, and…

  10. Serotype cycles in cholera dynamics

    OpenAIRE

    Koelle, Katia; Pascual, Mercedes; Yunus, Md.

    2006-01-01

    Interest in understanding strain diversity and its impact on disease dynamics has grown over the past decade. Theoretical disease models of several co-circulating strains indicate that incomplete cross-immunity generates conditions for strain-cycling behaviour at the population level. However, there have been no quantitative analyses of disease time-series that are clear examples of theoretically expected strain cycling. Here, we analyse a 40-year (1966–2005) cholera time-series from Banglade...

  11. Limit cycle vibrations in turbomachinery

    Science.gov (United States)

    Ryan, S. G.

    1991-01-01

    The focus is on an examination of rotordynamic systems which are simultaneously susceptible to limit cycle instability and subharmonic response. Characteristics of each phenomenon are determined as well as their interrelationship. A normalized, single mass rotor model is examined as well as a complex model of the high pressure fuel turbopump and the Space Shuttle Main Engine. Entrainment of limit cycle instability by subharmonic response is demonstrated for both models. The nonuniqueness of the solution is also demonstrated.

  12. On Cycles in AS Relationships

    CERN Document Server

    Dimitropoulos, Xenofontas; Krioukov, Dmitri

    2008-01-01

    Several users of our AS relationship inference data (http://www.caida.org/data/active/as-relationships/), released with cs/0604017, asked us why it contained AS relationship cycles, e.g., cases where AS A is a provider of AS B, B is a provider of C, and C is a provider of A, or other cycle types. Having been answering these questions in private communications, we have eventually decided to write down our answers here for future reference.

  13. Integrated coal gasification combined cycle

    Science.gov (United States)

    Richards, P. C.; Wijffels, J.-B.; Zuideveld, P. L.

    Features of the integrated coal gasification combined cycle power plants are described against the backdrop of the development and first commercial application of the shell coal gasification process. Focus is on the efficiency and excellent environmental performance of the integrated coal gasification combined power plants. Current IGCC projects are given together with an outline of some of the options for integrating coal gasification with combined cycles and also other applications of synthesis gas.

  14. Life cycle and textiles recycling

    OpenAIRE

    2011-01-01

    Within the vision of development of European textile and clothing industry for 2020 from the standpoint of the European Technology Platform (ETP), the paper analyzes a segment which includes life cycle and recycling of textiles. It is the fact that the complexity of new textile and clothing product has caused the development of new-higher standards. For this reason in development of highly innovative products, today is included also quality assurance during his whole life cycle starting from ...

  15. Revisiting the life cycle of dung fungi, Including Sordaria fimicola

    Science.gov (United States)

    George Newcombe; Jason Campbell; David Griffith; Melissa Baynes; Karen Launchbaugh; Rosemary Pendleton

    2016-01-01

    Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem...

  16. Teaching Diverse Students: Focus on the Learning Cycle.

    Science.gov (United States)

    Erb, Thomas O.

    1994-01-01

    Young adolescents have diverse learning needs. If teachers accommodated the complete learning cycle by designing instructional units that began with romance activities, led to precision opportunities, and culminated in generalization projects, students could develop their diverse talents while avoiding boredom with uninspiring precision…

  17. LIFE CYCLE DESIGN OF A FUEL TANK SYSTEM

    Science.gov (United States)

    This life cycle design (LCD) project was a collaborative effort between the National Pollution Prevention Center at the University of Michigan, General Motors (GM), and the U.S. Environmental Protection Agency (EPA). The primary objective of this project was to apply life cyc...

  18. Site-dependent life-cycle impact assessment of acidification

    DEFF Research Database (Denmark)

    Potting, Josepha Maria Barbara; Schöpp, W.; Blok, Kornelis;

    1998-01-01

    for acidification, eutrophication via air; and tropospheric ozone formation. The application of the acidification factors in LCIA is very straightforward. The only additional data required, the geographical site of the emission, is generally provided by current life-cycle inventory analysis. The acidification...

  19. Secular Cycles and Millennial Trends

    Directory of Open Access Journals (Sweden)

    Andrey Korotayev

    2016-12-01

    Full Text Available In the current paper we investigate the relation between secular cycles and millennial trends. The tests we have performed suggest that the structure of millennial trends cannot be adequately understood without secular cycles being taken into consideration. At a certain level of analysis millennial trends turn out to be a virtual byproduct of the demographic cycle mechanisms, which turn out to incorporate certain trend-creating mechanisms. Demographic-political cycle models can serve as a basis for the development and testing of models accounting not only for cycles but also for secular trends. In order to do this, we suggest to alter the basic assumptions of the earlier generations of demographic cycle models (that both the carrying capacity of land and the polity size are constant. The variables such as carrying capacity of land, cultural complexity, and empire sizes are actually not constant, but rather experience long-term trend dynamics in the rise, and the new generation of models needs to account for this fact.

  20. The NEWS Water Cycle Climatology

    Science.gov (United States)

    Rodell, Matthew; Beaudoing, Hiroko Kato; L'Ecuyer, Tristan; William, Olson

    2012-01-01

    NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water cycle component of the first phase of the project, which include seasonal (monthly) climatologies of water fluxes over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the flux estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized flux estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.

  1. Solar Cycle Predictions (Invited Review)

    Science.gov (United States)

    Pesnell, W. Dean

    2012-11-01

    Solar cycle predictions are needed to plan long-term space missions, just as weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on low-Earth orbit spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as the reduced propellant load is consumed more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5 - 20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations of how those predictions could be made more accurate in the future are discussed.

  2. A biogeochemical cycle for aluminium?

    Science.gov (United States)

    Exley, Christopher

    2003-09-15

    The elaboration of biogeochemical cycles for elements which are known to be essential for life has enabled a broad appreciation of the homeostatic mechanisms which underlie element essentiality. In particular they can be used effectively to identify any part played by human activities in element cycling and to predict how such activities might impact upon the lithospheric and biospheric availability of an element in the future. The same criteria were the driving force behind the construction of a biogeochemical cycle for aluminium, a non-essential element which is a known ecotoxicant and a suspected health risk in humans. The purpose of this exercise was to examine the concept of a biogeochemical cycle for aluminium and not to review the biogeochemistry of this element. The cycle as presented is rudimentary and qualitative though, even in this nascent form, it is informative and predictive and, for these reasons alone, it is deserving of future quantification. A fully fledged biogeochemical cycle for aluminium should explain the biospheric abundance of this element and whether we should expect its (continued) active involvement in biochemical evolution.

  3. Generalized Probability Functions

    Directory of Open Access Journals (Sweden)

    Alexandre Souto Martinez

    2009-01-01

    Full Text Available From the integration of nonsymmetrical hyperboles, a one-parameter generalization of the logarithmic function is obtained. Inverting this function, one obtains the generalized exponential function. Motivated by the mathematical curiosity, we show that these generalized functions are suitable to generalize some probability density functions (pdfs. A very reliable rank distribution can be conveniently described by the generalized exponential function. Finally, we turn the attention to the generalization of one- and two-tail stretched exponential functions. We obtain, as particular cases, the generalized error function, the Zipf-Mandelbrot pdf, the generalized Gaussian and Laplace pdf. Their cumulative functions and moments were also obtained analytically.

  4. Pfaffians and nonintersecting paths in graphs with cycles: Grassmann algebra methods

    CERN Document Server

    Carrozza, Sylvain

    2016-01-01

    After recalling the definition of Grassmann algebra and elements of Grassmann--Berezin calculus, we use the expression of Pfaffians as Grassmann integrals to generalize a series of formulas relating generating functions of paths in digraphs to Pfaffians. We start with the celebrated Lindstr\\"om-Gessel-Viennot formula, which we derive in the general case of a graph with cycles. We then make further use of Grassmann algebraic tools to prove a generalization of the results of (Stembridge 1990). Our results, which are applicable to graphs with cycles, are formulated in terms of systems of nonintersecting paths and nonintersecting cycles in digraphs.

  5. Very high cycle fatigue testing of concrete using ultrasonic cycling

    Energy Technology Data Exchange (ETDEWEB)

    Karr, Ulrike; Schuller, Reinhard; Fitzka, Michael; Mayer, Herwig [Univ. of Natural Resources and Life Sciences, Vienna (Austria). Inst. of Physics and Materials Science; Denk, Andreas; Strauss, Alfred [Univ. of Natural Resources and Life Sciences, Vienna (Austria)

    2017-06-01

    The ultrasonic fatigue testing method has been further developed to perform cyclic compression tests with concrete. Cylindrical specimens vibrate in resonance at a frequency of approximately 20 kHz with superimposed compressive static loads. The high testing frequency allows time-saving investigations in the very high cycle fatigue regime. Fatigue tests were carried out on ''Concrete 1'' (compressive strength f{sub c} = 80 MPa) and ''Concrete 2'' (f{sub c} = 107 MPa) under purely compressive loading conditions. Experiments at maximum compressive stresses of 0.44 f{sub c} (Concrete 1) and 0.38 f{sub c} (Concrete 2) delivered specimen failures above 109 cycles, indicating that no fatigue limit exists for concrete below one billion load cycles. Resonance frequency, power required to resonate the specimen and second order harmonics of the vibration are used to monitor fatigue damage in situ. Specimens were scanned by X-ray computed tomography prior to and after testing. Fatigue cracks were produced by ultrasonic cycling in the very high cycle fatigue regime at interfaces of grains as well as in cement. The possibilities as well as limitations of ultrasonic fatigue testing of concrete are discussed.

  6. What cycles the cell? -Robust autonomous cell cycle models.

    Science.gov (United States)

    Lavi, Orit; Louzoun, Yoram

    2009-12-01

    The cell cycle is one of the best studied cellular mechanisms at the experimental and theoretical levels. Although most of the important biochemical components and reactions of the cell cycle are probably known, the precise way the cell cycle dynamics are driven is still under debate. This phenomenon is not atypical to many other biological systems where the knowledge of the molecular building blocks and the interactions between them does not lead to a coherent picture of the appropriate dynamics. We here propose a methodology to develop plausible models for the driving mechanisms of embryonic and cancerous cell cycles. We first define a key property of the system (a cyclic behaviour in the case of the embryonic cell cycle) and set mathematical constraints on the types of two variable simplified systems robustly reproducing such a cyclic behaviour. We then expand these robust systems to three variables and reiterate the procedure. At each step, we further limit the type of expanded systems to fit the known microbiology until a detailed description of the system is obtained. This methodology produces mathematical descriptions of the required biological systems that are more robust to changes in the precise function and rate constants. This methodology can be extended to practically any type of subcellular mechanism.

  7. Using mental mapping to unpack perceived cycling risk.

    Science.gov (United States)

    Manton, Richard; Rau, Henrike; Fahy, Frances; Sheahan, Jerome; Clifford, Eoghan

    2016-03-01

    concludes that mental mapping is a highly useful tool for assessing perceptions of cycling risk with a strong visual aspect and significant potential for public participation. This distinguishes it from more traditional cycling safety assessment tools that focus solely on the technical assessment of cycling infrastructure. Further development of online mapping tools is recommended as part of bicycle suitability measures to engage cyclists and the general public and to inform 'soft' and 'hard' cycling policy responses.

  8. On the aerosol weekly cycle spatiotemporal variability over Europe

    Directory of Open Access Journals (Sweden)

    A. K. Georgoulias

    2011-05-01

    Full Text Available In this work, we focus on the spatial and temporal variability of the aerosol weekly cycle over Europe as these were recorded from TERRA MODIS and AQUA MODIS satellite instruments. Aerosol optical properties retrieved from MODIS TERRA (February 2000–February 2009 and AQUA (July 2002–December 2008 were used to produce an aerosol weekly cycle index. First, the general aerosol optical depth (AOD550 nm weekly patterns were defined at a 1° × 1° resolution using the satellite-based index and six regions of interest were selected. To remove episodic dust transport events, two different aerosol flags, employing fine mode ratio (FMR550 nm and AOD550 nm data, were applied diagnostically, showing that the observed weekly cycles over Europe are due to continental aerosols. A second spatial averaging method was then used for the investigation of the weekly variability and the statistical significance of the weekly cycle over each of the previously selected regions. Three major weekly cycle plumes are observed over Europe. A strong positive (higher values during midweek weekly cycle plume appears over Central Europe, while a strong negative (higher values during weekend weekly plume appears over the Iberian Peninsula and the North-eastern Europe. The temporal examination of the weekly cycles shows that in some areas there are seasonal differences in the sign of the weekly cycle. The aerosol weekly variability over different regions in Europe was examined in conjunction with the dominating synoptic wind patterns from the NCEP/NCAR reanalysis, showing that the seasonal weekly cycle plumes over regions situated in the eastern Europe and the Mediterranean Sea could be partly attributed to the westerly transport of continental aerosols.

  9. On the aerosol weekly cycle spatiotemporal variability over Europe

    Science.gov (United States)

    Georgoulias, A. K.; Kourtidis, K. A.

    2011-05-01

    In this work, we focus on the spatial and temporal variability of the aerosol weekly cycle over Europe as these were recorded from TERRA MODIS and AQUA MODIS satellite instruments. Aerosol optical properties retrieved from MODIS TERRA (February 2000-February 2009) and AQUA (July 2002-December 2008) were used to produce an aerosol weekly cycle index. First, the general aerosol optical depth (AOD550 nm) weekly patterns were defined at a 1° × 1° resolution using the satellite-based index and six regions of interest were selected. To remove episodic dust transport events, two different aerosol flags, employing fine mode ratio (FMR550 nm) and AOD550 nm data, were applied diagnostically, showing that the observed weekly cycles over Europe are due to continental aerosols. A second spatial averaging method was then used for the investigation of the weekly variability and the statistical significance of the weekly cycle over each of the previously selected regions. Three major weekly cycle plumes are observed over Europe. A strong positive (higher values during midweek) weekly cycle plume appears over Central Europe, while a strong negative (higher values during weekend) weekly plume appears over the Iberian Peninsula and the North-eastern Europe. The temporal examination of the weekly cycles shows that in some areas there are seasonal differences in the sign of the weekly cycle. The aerosol weekly variability over different regions in Europe was examined in conjunction with the dominating synoptic wind patterns from the NCEP/NCAR reanalysis, showing that the seasonal weekly cycle plumes over regions situated in the eastern Europe and the Mediterranean Sea could be partly attributed to the westerly transport of continental aerosols.

  10. The Water Cycle Solutions Network

    Science.gov (United States)

    Houser, P.; Belvedere, D.; Imam, B.; Schiffer, R.; Schlosser, C.; Gupta, H.; Welty, C.; Vörösmarty, C.; Matthews, D.; Lawford, R.

    2006-12-01

    The goal of the Water cycle Solutions Network is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend research results to augment decision support tools and meet national needs. WaterNet will engage relevant NASA water cycle research resources and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect water cycle research results (WCRs) towards the improvement of water-related Decision Support Tools (DSTs). An actionable database includes enough sufficient knowledge about its nodes and their heritage so that connections between these nodes are identifiable and robust. Recognizing the many existing highly valuable water-related science and application networks, we will focus the balance of our efforts on enabling their interoperability in a solutions network context. We will initially focus on identification, collection, and analysis of the two end points, these being the WCRs and water related DSTs. We will then develop strategies to connect these two end points via innovative communication strategies, improved user access to NASA resources, improved water cycle research community appreciation for DST requirements, improved policymaker, management and stakeholder knowledge of NASA research and application products, and improved identification of pathways for progress. Finally, we will develop relevant benchmarking and metrics, to understand the network's characteristics, to optimize its performance, and to establish sustainability. The WaterNet will deliver numerous pre-evaluation reports that will identify the pathways for improving the collective ability of the water cycle community to routinely harness WCRs that address crosscutting water cycle challenges.

  11. Long Photometric Cycles in Hot Algols

    Science.gov (United States)

    Mennickent, R. E.

    2017-06-01

    We summarize the development of the field of Double Periodic Variables (DPVs, Mennickent et al. 2003) during the last fourteen years, placing these objects in the context of intermediate-mass close interacting binaries similar to β Persei (Algol) and β Lyrae (Sheliak) which are generally called Algols.DPVs show enigmatic long photometric cycles lasting on average about 33 times the orbital period, and have physical properties resembling, in some aspects, β Lyrae. About 200 of these objects have been found in the Galaxy and the Magellanic Clouds. Light curve models and orbitally resolved spectroscopy indicate that DPVs are semi-detached interacting binaries consisting of a near main-sequence B-type star accreting matter from a cooler giant and surrounded by an optically thick disc. This disc contributes a significant fraction of the system luminosity and its luminosity is larger than expected from the phenomenon of mass accretion alone. In some systems, an optically thin disc component is observed in well developed Balmer emission lines. The optically thick disc shows bright zones up to tens percent hotter than the disc, probably indicating shocks resulting from the gas and disc stream dynamics. We conjecture that a hotspot wind might be one of the channels for a mild systemic mass loss, since evidence for jets, winds or general mass loss has been found in β Lyrae, AU Mon, HD 170582, OGLE 05155332-6925581 and V 393 Sco. Also, theoretical work by Van Rensbergen et al. (2008) and Deschamps et al. (2013) suggests that hotspot could drive mass loss from Algols. We give special consideration to the recently published hypothesis for the long cycle, consisting of variable mass transfer driven by a magnetic dynamo (Schleicher and Mennickent 2017). The Applegate (1992) mechanism should modify cyclically the equatorial radius of the chromospherically active donor producing cycles of enhanced mass loss through the inner Lagrangian point. Chromospheric emission in V 393 Sco

  12. GENERALIZED WEAK FUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    丁夏畦; 罗佩珠

    2004-01-01

    In this paper the authors introduce some new ideas on generalized numbers and generalized weak functions. They prove that the product of any two weak functions is a generalized weak function. So in particular they solve the problem of the multiplication of two generalized functions.

  13. Generalized holomorphic structures

    Science.gov (United States)

    Wang, Yicao

    2014-12-01

    We define the notion of generalized holomorphic principal bundles and establish that their associated vector bundles of holomorphic representations are generalized holomorphic vector bundles defined by M. Gualtieri. Motivated by our definition, several examples of generalized holomorphic structures are constructed. A reduction theorem of generalized holomorphic structures is also included.

  14. How general is general information construct?

    Directory of Open Access Journals (Sweden)

    Predrag Zarevski

    2005-04-01

    Full Text Available There is a small number of constructs in the field of differential psychology that have raised so much debate between psychologists and professionals in related disciplines as is the case of general (verbal information construct. It seemed reasonable to test the validity of this construct measured with general information test in comparison with other measures of knowledge (cultural knowledge, vocabulary, knowledge of the most recent events, foreign language knowledge, and a standard verbal type g test. A sample of 376 candidates for state services was tested in a selection situation. Three analyses were conducted to determine the position of general information test in the space of other verbal competency measures. The first analysis questioned latent structure of the space of four tests having the same format and asking about the knowledge of international terms, general culture, knowledge of most recent events, and general information. The second analysis included the g-factor intelligence test so to see how the above described structure changes when this new test is introduced. The third analysis introduced an English language test. In all of the three component analyses only one eigenvalue was larger than 1 and it explained between 52 and 64% of variance. In all analyses general information test had the highest projection on the only significant latent dimension of these cognitive spaces. In other words, it can be concluded that the construct of general information is in the center of this hyperconus. That is why we consider measurement of general information knowledge, as well as the construct itself, to be an important question in psychological diagnostics. Thus, it is important to go further with the investigation of this construct because it does not seem that it is named general information by accident.

  15. Extrusion cycles during dome-building eruptions

    Science.gov (United States)

    de' Michieli Vitturi, M.; Clarke, A. B.; Neri, A.; Voight, B.

    2013-06-01

    We identify and quantify controls on the timescales and magnitudes of cyclic (periodic) volcanic eruptions using the numerical model DOMEFLOW (de' Michieli Vitturi et al., 2010) which was developed by the authors for magma systems of intermediate composition. DOMEFLOW treats the magma mixture as a liquid continuum with dispersed gas bubbles and crystals in thermodynamic equilibrium with the melt and assumes a modified Poiseuille form of the viscous term for fully developed laminar flow in a conduit of cylindrical cross-section. During ascent, magma pressure decreases and water vapor exsolves and partially degasses from the melt as the melt simultaneously crystallizes, causing changes in mixture density and viscosity. Two mechanisms previously proposed to cause periodic eruption behavior have been implemented in the model and their corresponding timescales explored. The first applies a stick-slip model in which motion of a shallow solid plug is resisted by static/dynamic friction, as described in Iverson et al. (2006). For a constant magma supply rate at depth, this mechanism yields cyclic extrusion with timescales of seconds to tens of seconds with values generally depending on assumed friction coefficients. The second mechanism does not consider friction but treats the plug as a high-viscosity Newtonian fluid. During viscous resistance, pressure beneath the degassed plug can increase sufficiently to overcome dome overburden, plug weight, and viscous forces, and ultimately drive the plug from the conduit. In this second model cycle periods are on the order of hours, and decrease with increasing magma supply rate until a threshold is reached, at which point periodicity disappears and extrusion rate becomes steady (vanishingly short periods). Magma volatile content for fixed chamber pressure has little effect on cycle timescales, but increasing volatile content increases mass flow rate and cycle magnitude as defined by the difference between maximum and minimum

  16. Introduction to general and generalized linear models

    CERN Document Server

    Madsen, Henrik

    2010-01-01

    IntroductionExamples of types of data Motivating examples A first view on the modelsThe Likelihood PrincipleIntroduction Point estimation theory The likelihood function The score function The information matrix Alternative parameterizations of the likelihood The maximum likelihood estimate (MLE) Distribution of the ML estimator Generalized loss-function and deviance Quadratic approximation of the log-likelihood Likelihood ratio tests Successive testing in hypothesis chains Dealing with nuisance parameters General Linear ModelsIntroduction The multivariate normal distribution General linear mod

  17. 东营凹陷盐家地区砂砾岩体沉积期次精细划分与对比%Fine division and correlation of conglomerate sedimentary cycles in Yanjia area of Dongying depression

    Institute of Scientific and Technical Information of China (English)

    宋明水; 李存磊; 张金亮

    2012-01-01

    东营凹陷盐家地区沙河街组四段上亚段(简称沙四上亚段)重力流舌状体式叠覆沉积的砂砾岩体不具备“层状”地层特征,应用常规方法进行沉积旋回划分和对比很难保证时间上的等时性.针对该问题,引入天文地层学中气候旋回受天文周期驱动的理论,研究砂砾岩体的形成条件及控制因素,对砂砾岩体进行时间域的等时性控制,然后在相同的时间域内进行旋回界面的识别与旋回对比.通过对研究区砂砾岩沉积进行米兰科维奇旋回特征分析,确定研究区地层旋回主要受偏心率周期控制,并计算得出第一优势旋回厚度为151.7m和第二优势旋回厚度为61.4m.以米兰科维奇旋回分析结果为主,同时结合层序地层学基准面旋回理论,根据岩心和成像测井相层序分析,确定地层划分方案,将研究区沙四上亚段划分为4个四级层序和1 1个五级层序.以优势旋回频率信息对测井曲线进行滤波处理,同时根据基准面旋回特征,以滤波后的曲线为依据进行地层旋回的横向对比,建立了地层旋回对比格架,实现砂砾岩体沉积期次的精细划分与对比.%The conglomerate in gravity-flow linguloid overlapped deposits of the upper sub-member of Member Sha-4 in Yanjia area of Dongying depression has no "stratified" layers, thus it is difficult to guarantee the isochroneity of the conglomerate through conventional depositional cycle division and correlation. In order to solve this problem, we studied formation conditions and controlling factors of the conglomerate by introducing a theory of astronomic stratigraphy that climatic cycles are driven by astronomic cycles. When the time domain of the conglomerate was isochronously defined, the identification of cyclic boundaries and the correlation of cycles could be achieved within an identical time domain. Through the Milankovitch cycle characteristic analysis on conglomerate deposits in the study area

  18. Focused training boosts revenue cycle skills, accountability.

    Science.gov (United States)

    Richmond, Craig

    2011-09-01

    In 2009, the MetroHealth System took its first steps toward creating a comprehensive revenue cycle university, with the goal of developing revenue cycle staff talent and achieving best-in-class revenue cycle operations. MetroHealth became a beta site for HFMA's online Credentialed Revenue Cycle Representative (CRCR) program, and asked its revenue cycle leaders to present classes on key revenue cycle issues. As of June 2011, 62 percent of 122 revenue cycle employees who had taken the CRCR course passed the exam. The CRCR designation is now a prerequisite for career advancement in certain revenue cycle areas at MetroHealth.

  19. Determination of the estrous cycle phases of rats: some helpful considerations

    OpenAIRE

    MARCONDES,F. K.; F. J. BIANCHI; A. P. TANNO

    2002-01-01

    The short length of the estrous cycle of rats makes them ideal for investigation of changes occurring during the reproductive cycle. The estrous cycle lasts four days and is characterized as: proestrus, estrus, metestrus and diestrus, which may be determined according to the cell types observed in the vaginal smear. Since the collection of vaginal secretion and the use of stained material generally takes some time, the aim of the present work was to provide researchers with some helpful consi...

  20. Origins of the supercontinent cycle

    Directory of Open Access Journals (Sweden)

    R. Damian Nance

    2013-07-01

    Full Text Available The supercontinent cycle, by which Earth history is seen as having been punctuated by the episodic assembly and breakup of supercontinents, has influenced the rock record more than any other geologic phenomena, and its recognition is arguably the most important advance in Earth Science since plate tectonics. It documents fundamental aspects of the planet's interior dynamics and has charted the course of Earth's tectonic, climatic and biogeochemical evolution for billions of years. But while the widespread realization of the importance of supercontinents in Earth history is a relatively recent development, the supercontinent cycle was first proposed thirty years ago and episodicity in tectonic processes was recognized long before plate tectonics provided a potential explanation for its occurrence. With interest in the supercontinent cycle gaining momentum and the literature expanding rapidly, it is instructive to recall the historical context from which the concept developed. Here we examine the supercontinent cycle from this perspective by tracing its development from the early recognition of long-term episodicity in tectonic processes, through the identification of tectonic cycles following the advent of plate tectonics, to the first realization that these phenomena were the manifestation of episodic supercontinent assembly and breakup.