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Sample records for growth ring width

  1. Simulation of tree ring-widths with a model for primary production, carbon allocation and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Harrison, S. P.; Prentice, I. C.; Falster, D.

    2014-07-01

    We present a simple, generic model of annual tree growth, called "T". This model accepts input from a first-principles light-use efficiency model (the P model). The P model provides values for Gross Primary Production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport-tissue, and fine root production and respiration, in such a way as to satisfy well-understood dimensional and functional relationships. Our approach thereby integrates two modelling approaches separately developed in the global carbon-cycle and forest-science literature. The T model can represent both ontogenetic effects (impact of ageing) and the effects of environmental variations and trends (climate and CO2) on growth. Driven by local climate records, the model was applied to simulate ring widths during 1958-2006 for multiple trees of Pinus koraiensis from the Changbai Mountain, northeastern China. Each tree was initialised at its actual diameter at the time when local climate records started. The model produces realistic simulations of the interannual variability in ring width for different age cohorts (young, mature, old). Both the simulations and observations show a significant positive response of tree-ring width to growing-season total photosynthetically active radiation (PAR0) and the ratio of actual to potential evapotranspiration (α), and a significant negative response to mean annual temperature (MAT). The slopes of the simulated and observed relationships with PAR0 and α are similar; the negative response to MAT is underestimated by the model. Comparison of simulations with fixed and changing atmospheric CO2 concentration shows that CO2 fertilization over the past 50 years is too small to be distinguished in the ring-width data given ontogenetic trends and interannual variability in climate.

  2. Simulation of tree-ring widths with a model for primary production, carbon allocation, and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Harrison, S. P.; Prentice, I. C.; Falster, D.

    2014-12-01

    We present a simple, generic model of annual tree growth, called "T". This model accepts input from a first-principles light-use efficiency model (the "P" model). The P model provides values for gross primary production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport tissue, and fine-root production and respiration in such a way as to satisfy well-understood dimensional and functional relationships. Our approach thereby integrates two modelling approaches separately developed in the global carbon-cycle and forest-science literature. The T model can represent both ontogenetic effects (the impact of ageing) and the effects of environmental variations and trends (climate and CO2) on growth. Driven by local climate records, the model was applied to simulate ring widths during the period 1958-2006 for multiple trees of Pinus koraiensis from the Changbai Mountains in northeastern China. Each tree was initialised at its actual diameter at the time when local climate records started. The model produces realistic simulations of the interannual variability in ring width for different age cohorts (young, mature, and old). Both the simulations and observations show a significant positive response of tree-ring width to growing-season total photosynthetically active radiation (PAR0) and the ratio of actual to potential evapotranspiration (α), and a significant negative response to mean annual temperature (MAT). The slopes of the simulated and observed relationships with PAR0 and α are similar; the negative response to MAT is underestimated by the model. Comparison of simulations with fixed and changing atmospheric CO2 concentration shows that CO2 fertilisation over the past 50 years is too small to be distinguished in the ring-width data, given ontogenetic trends and interannual variability in climate.

  3. Tree growth inference and prediction from diameter censuses and ring widths.

    PubMed

    Clark, James S; Wolosin, Michael; Dietze, Michael; Ibáñez, Inés; LaDeau, Shannon; Welsh, Miranda; Kloeppel, Brian

    2007-10-01

    Estimation of tree growth is based on sparse observations of tree diameter, ring widths, or increments read from a dendrometer. From annual measurements on a few trees (e.g., increment cores) or sporadic measurements from many trees (e.g., diameter censuses on mapped plots), relationships with resources, tree size, and climate are extrapolated to whole stands. There has been no way to formally integrate different types of data and problems of estimation that result from (1) multiple sources of observation error, which frequently result in impossible estimates of negative growth, (2) the fact that data are typically sparse (a few trees or a few years), whereas inference is needed broadly (many trees over many years), (3) the fact that some unknown fraction of the variance is shared across the population, and (4) the fact that growth rates of trees within competing stands are not independent. We develop a hierarchical Bayes state space model for tree growth that addresses all of these challenges, allowing for formal inference that is consistent with the available data and the assumption that growth is nonnegative. Prediction follows directly, incorporating the full uncertainty from inference with scenarios for "filling the gaps" for past growth rates and for future conditions affecting growth. An example involving multiple species and multiple stands with tree-ring data and up to 14 years of tree census data illustrates how different levels of information at the tree and stand level contribute to inference and prediction. PMID:17974333

  4. Growth rate and ring width variability of teak, Tectona grandis (Verbenaceae) in an unmanaged forest in East Timor.

    PubMed

    Sousa, Vicelina B; Cardoso, Sofia; Quilhó, Teresa; Pereira, Helena

    2012-03-01

    Teak (Tectona grandis) is one of the most valuable timbers in international trade and an important species for tropical forestry. Teak is found on the island of East Timor but no information is available on teak growth from this region. A pure stand planted in 1940-50 in the North of East Timor and left unmanaged was studied. Fifteen trees were sampled in October-November 2003 and stem discs taken at three height levels of its height (1.7m, 9.5m and 18.7m), and cores were collected at DBH. Transverse surfaces of the discs and cores were polished for ring identification. Core cross sections were first digitized and disc cross sections were observed under the microscope. Three randomly selected radii were analyzed in each disc. Ring width measurement and ring counting were done using image analysis software. The distinction between heartwood and sapwood was performed macroscopically by colour difference, and heartwood radius and sapwood width were measured. The relationship between stem and heartwood radius was studied for each disc and heartwood percentage by radius was determined. Radial ring width curves are presented for the different axial positions within the stem, and ring width variability was analyzed. Growth rates were calculated and age-radius relationships were estimated using cumulative growth curves. Growth rings were large and well defined in the juvenile phase, reflecting the specie's fast-growing character. The year-to-year variation of ring width showed a similar pattern among trees. Mean ring width ranged between 4.3-7.3mm for the first 20 years and 3.3-5.1mm for 30 to 45 years. Pith eccentricity was evident in the lower part of the stem and ring wedging occurred. On average, heartwood represented 84% of the radius and sapwood contained 6 to 11 rings. The age-related variation of ring width and the occurrence in the lower part of the tree stems of eccentricity and wedging rings, highlights the importance of appropriate stand management

  5. Soil Warming and Fertilization Effects on Growth Ring Widths of Arctic Shrubs - Application of a Novel Dendroecological Approach.

    NASA Astrophysics Data System (ADS)

    Iturrate Garcia, M.; Heijmans, M.; Schweingruber, F. H.; Niklaus, P. A.; Schaepman-Strub, G.

    2015-12-01

    Climate warming is suggested as the main driver of shrub expansion in arctic tundra regions. Shrub expansion may have consequences on biodiversity and climate, especially through its feedbacks with the energy budget. A better understanding of shrub expansion mechanisms, including growth rate patterns and stem anatomy changes, and their sensitivity to climate is needed in order to quantify related feedbacks. We present a novel dendroecological approach to determine the response of three arctic shrub species to increased soil temperature and nutrients. A full factorial block-design experiment was run for four years with a total of thirty plots. Six individuals of each species were sampled from each plot to test for treatment effects on growth rate and stem anatomy. We compared the ring width of the four years of experiment with the one of the four previous years. The preliminary results for Betula nana and Salix pulchra suggest a significant effect of the treatments on the growth ring width. The response is stronger in Salix pulchra than in Betula nana individuals. And, while Salix pulchra is more sensitive to the combined soil warming and fertilization treatment, Betula nana is to the fertilization treatment. We could not observe an effect of treatment on the stem anatomy, likely because bark thickness co-varies with age. We found significant positive correlations of cork, cortex and phloem thickness with xylem thickness (used as a proxy of age), and a significant difference in stem anatomy between species. The results suggest species-specific growth sensitivity to soil warming and nutrient enhancement. The use of experimental dendroecology by manipulating environmental conditions according to future climate scenarios and testing effects on shrub anatomy and annual growth will increase our understanding on shrub expansion mechanisms. Ongoing plant trait analysis and consecutive application in a 3D radiative transfer model will allow to quantify the feedback of

  6. Traffic pollution affects P. pinea growth according to tree ring width and C and N isotopic composition

    NASA Astrophysics Data System (ADS)

    Battipaglia, Giovanna; Marzaioli, Fabio; Lubritto, Carmine; Altieri, Simona; Strumia, Sandro; Cherubini, Paolo; Cotrufo, M. Francesca

    2010-05-01

    Urbanization and industrialization are rapidly growing, as a consequence roads and their associated vehicular traffic exerts major and increasing impacts on adjacent ecosystems. Various studies have shown the impact of vehicle exhausts on road side vegetation through their visible and non-visible effects (Farmer and Lyon 1977, Sarkar et al., 1986, Angold 1997, Nuhoglu 2005) but, presently there is little known about the long term effect of air pollution on vegetation and on trees, in particular. Developing proxies for atmospheric pollution that would be used to identify the physiological responses of trees under roadside car exhaust pollution stress is needed. In this context we propose a novel method to determine the effect of car exhaust pollution on tree growth, coupling classical dendrochronological analyses and analyses of 15N and 13C in tree rings, soils and leaves with tree ring radiocarbon (14C) data. Pinus pinea individuals, adjacent to main roads in the urban area of Caserta (South Italy) and exposed to large amounts of traffic exhausts since 1980, were sampled and the time-related trend in the growth residuals was estimated. We found a consistent decrease in the ring width starting from 1980, with a slight increase in δ13C value, which was considered to be a consequence of environmental stress. No clear pattern was identified in δ15N, while an increasing effect of the fossil fuel dilution on the atmospheric bomb-enriched 14C background was detected in tree rings, as a consequence of the increase in traffic exhausts. Our findings suggest that radiocarbon is a very sensitive tool to investigate small-scale (i.e. traffic exhaust at the level crossing) and large-scale (urban area pollution) induced disturbances. References Angold PG. Impact of a road upon adjacent heathland vegetations: effect on plant species compositions. J Appl Ecol 1997; 34 (2): 409-417. Farmer JC, Lyon TDB. Lead in Glasgow street dirt and soil. Sci Tot Environ 1977; 8: 89-93. Nuhoglu

  7. Dependence of tree ring stable isotope abundances and ring width on climate in Finnish oak.

    PubMed

    Hilasvuori, Emmi; Berninger, Frank

    2010-05-01

    We measured ring widths and isotopic abundances of carbon, oxygen and hydrogen (delta(13)C, delta(18)O and delta(2)H) from the latewood of tree rings of pedunculate oak (Quercus robur L.) in its distributional northern limit in Southern Finland. Ring width was observed to be related to precipitation and relative humidity but not significantly to temperature. delta(13)C and delta(18)O were significantly related to all studied climatic variables, most strongly to cloud cover. Variations in delta(2)H were discovered to be complex combinations of signals from biochemical and physical processes. The results suggest that oaks in Finland can be used as a source of climate information. delta(18)O was discovered to be especially promising as it showed the strongest climate signal and highest common signal between trees. The relationship between climate and ring width indicates that water availability is the main control of ring radial growth. This is supported by the isotope data. High correlation between delta(13)C and delta(18)O time series indicates that photosynthetic carbon assimilation is limited by stomatal control. Therefore, in contrast to the expected temperature limitation, our data indicate that drought limits oak growth more than cold temperatures on the border of its northernmost distribution range. PMID:20357343

  8. On the Assimilation of Tree-Ring-Width Chronologies

    NASA Astrophysics Data System (ADS)

    Acevedo, Walter; Reich, Sebastian; Cubasch, Ulrich

    2015-04-01

    Data assimilation (DA) of climate proxy records is currently acknowledged as a promising approach to the paleoclimate reconstruction problem, with the potential to bring physical consistency to reconstructed fields. Previous paleo-DA studies have typically assumed a linear relationship between climate forcing and the resulting proxy data, whereas there exist growing evidence of complex, potentially non-linear, proxy formation processes. Accordingly, it appears natural to simulate the proxy response to climate in a more realistic fashion, by way of proxy-specific forward models. Following this train of thought, we investigate the assimilation of the most traditional climate proxy type, Tree-Ring-Width (TRW) chronologies, using the process-based tree-ring growth forward model Vaganov-Shashkin-Lite (VSL) and ensemble Kalman filter (EnKF) techniques. Used as observation operator, VSL's formulation implies three compounding, challenging features: (i) time averaging, (ii) "switching recording" of 2 variables and (iii) bounded response windows leading to "thresholded response". DA experiments involving VSL-based pseudo-TRW observations are performed first for a chaotic 2-scale dynamical system, used as a cartoon of the atmosphere-land system, and then for an atmospheric general circulation model of intermediate complexity. Our results reveal that VSL's nonlinearities may considerable deteriorate the performance of EnKF for Time-Averaged (TA) estimation, as compared to the utilization of a TA linear observation operator. Moreover, we show that this assimilation skill loss can be considerably reduced by embedding VSL's formulation into fuzzy logic theory, which fosters new interpretations of tree-ring growth limitation processes.

  9. Hydrologic inferences from ring widths of flood-damaged trees, Potomac River, Maryland

    USGS Publications Warehouse

    Yanosky, T.M.

    1982-01-01

    Year-to-year variability in the ring widths of trees on flood plains along two reaches of the Potomac River near Washington, D.C., seems in large part to be related to differences in flood-flow regimes. Trees directly exposed to high flood velocities are damaged more often than sheltered trees and thus exhibit more variable ring-width patterns. The ring-width variability of unsheltered trees on low levels of flood plains is greater than that of trees on high levels, indicating that variability values are positively correlated with flood frequency. Sheltered trees, however, have less variable ring-width patterns than those of unsheltered trees, and variability is not correlated with flood frequency. As a result, ring-width variations may be used to estimate the probability of flood damage along local channel reaches of a stream. Growth responses after hydrologic catastrophies in 1948 and 1972 indicate that rings of flood-plain trees can be used to document the occurrence and crest altitude of high-magnitude floods. ?? 1982 Springer-Verlag New York Inc.

  10. Hydrologic inferences from ring widths of flood-damaged trees, Potomac River, Maryland

    NASA Astrophysics Data System (ADS)

    Yanosky, Thomas M.

    1982-03-01

    Year-to-year variability in the ring widths of trees on flood plains along two reaches of the Potomac River near Washington, D.C., seems in large part to be related to differences in flood-flow regimes. Trees directly exposed to high flood velocities are damaged more often than sheltered trees and thus exhibit more variable ring-width patterns. The ring-width variability of unsheltered trees on low levels of flood plains is greater than that of trees on high levels, indicating that variability values are positively correlated with flood frequency. Sheltered trees, however, have less variable ring-width patterns than those of unsheltered trees, and variability is not correlated with flood frequency. As a result, ring-width variations may be used to estimate the probability of flood damage along local channel reaches of a stream. Growth responses after hydrologic catastrophies in 1948 and 1972 indicate that rings of flood-plain trees can be used to document the occurrence and crest altitude of high-magnitude floods.

  11. An overview of tree-ring width records across the Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    St. George, Scott

    2014-07-01

    This review describes the structure and characteristics of the Northern Hemisphere tree-ring width network, and examines the associations between these data and key aspects of local climate and the global climate system. Even though all ring-width records describe the same aspect of tree growth, there are major regional differences in the nature and clarity of climate information preserved within these data across the hemisphere. In North America, many chronologies record climate variability during the growing season but winter precipitation also exerts a considerable and sometimes dominant control on tree-ring formation. Almost all ring-width records from Europe and Asia reflect the influence of climate during summer, with the effects of temperature being more prominent than precipitation. Mapping teleconnection patterns associated with major climate modes show that ENSO and the AMO have stronger and more consistent effects on tree growth than do the PDO, PNA, and NAO. The ENSO teleconnection, which seems to be communicated principally through its effect on winter precipitation, is evident within the highest number of ring-width records overall and is particularly strong in western North America. The AMO's expression in ring width is consistent across drought sensitive-records from the American Southwest and central Rocky Mountains, which may reflect its influence on moisture flux into the western interior of North America during summer. In comparison, the ring-width responses to the PDO, PNA, and NAO are less spatially coherent across the network and appear be connected through a more complex chain of causes linking climate modes, local climate and seasonal tree growth. Because the Northern Hemisphere ring-width network is now so large, it is more crucial than ever to ensure our understanding of tree-environment relations is not influenced by decisions to include or exclude certain records. As an initial step, it would be helpful if paleoclimate reconstructions

  12. [Chinese pine tree ring width chronology and its relations to climatic conditions in Qianshan Mountains].

    PubMed

    Chen, Zhen-Ju; Sun, Yu; He, Xing-Yuan; Chen, Wei; Shao, Xue-Mei; Zhang, Hua-Yu; Wang, Zhong-Yu; Liu, Xiao-Yu

    2007-10-01

    Taking Chinese pine in Qianshan Mountains as a sample, the tree ring width chronology including standard, residual, and Arstan chronologies was established. The results showed that the tree ring width of Chinese pine had a higher correlation with the temperature in May - July and in September - November, and significant positive correlations were observed between the tree ring width and the extreme minimum temperature in July and mean minimum temperature in September. The chronology had significant or very significant correlations with the extreme minimum temperature in December and next January, mean minimum temperature in January, annual precipitation, and the precipitation in April, May and last December. Chinese pine had stronger responses to the monthly/yearly water vapor pressure and relative humidity. The yearly and most monthly evaporation had negative effects on the growth, being most significant for the evaporation in April - July. The narrowed tree rings recorded by the chronology demonstrated the 30 times of extreme drought since 1 800. The growth of Chinese pine in Qianshan Mountains was also affected by the climate changes on global and hemisphere scales. There existed 11-, 23- and 50- year- common periodicity between the chronology and solar activity, and 10-, 20- and 45- year- common periodicity between the chronology and geomagnetic activity. PMID:18163297

  13. A Statistical Reconstruction of Bivariate Climate from Tree Ring Width Measurements Using Scientifically Motivated Process Models.

    NASA Astrophysics Data System (ADS)

    Tipton, J.; Hooten, M.; Pederson, N.; Tingley, M.; Bishop, D. A.

    2014-12-01

    The ability to reconstruct historical climate is important to understanding how climate has changed in the past. The instrumental record of temperature and precipitation only spans the most recent centuries. Thus, reconstructions of the climate features are typically based on proxy archives. The proxy archives integrate climate information through biological, geological, physical, and chemical processes. Tree ring widths provide one of the most spatially and temporally rich sources of high quality climate proxy data. However, the statistical reconstruction of paleoclimate from tree ring widths is quite challenging because the climate signal is inherently multi-dimensional while tree ring widths are a one dimensional data source. We propose a Bayesian Hierarchical model using a non-linear, scientifically motivated tree ring growth models to reconstruct multivariate climate (i.e., temperature and precipitation) in the Hudson Valley region of New York. Our proposed model extends and enhances former methods in a number of ways. We allow for species-specific responses to climate, which further constrains the many-to-one relationship between tree rings and climate. The resulting model allows for prediction of reasonable climate scenarios given tree ring widths. We explore a natural model selection framework that weighs the influence of multiple candidate growth models in terms of their predictive ability. To enable prediction backcasts, the climate variables are modeled with an underlying continuous time latent process. The continuous time process allows for added flexibility in the climate response through time at different temporal scales and enables investigation of differences in climate between the reconstruction period and the instrumental period. Validation of the model's predictive abilities is achieved through a pseudo-proxy simulation experiment where the quality of climate predictions are measured by out of sample performance based on a proper local scoring

  14. Towards the assimilation of tree-ring-width records using ensemble Kalman filtering techniques

    NASA Astrophysics Data System (ADS)

    Acevedo, Walter; Reich, Sebastian; Cubasch, Ulrich

    2016-03-01

    This paper investigates the applicability of the Vaganov-Shashkin-Lite (VSL) forward model for tree-ring-width chronologies as observation operator within a proxy data assimilation (DA) setting. Based on the principle of limiting factors, VSL combines temperature and moisture time series in a nonlinear fashion to obtain simulated TRW chronologies. When used as observation operator, this modelling approach implies three compounding, challenging features: (1) time averaging, (2) "switching recording" of 2 variables and (3) bounded response windows leading to "thresholded response". We generate pseudo-TRW observations from a chaotic 2-scale dynamical system, used as a cartoon of the atmosphere-land system, and attempt to assimilate them via ensemble Kalman filtering techniques. Results within our simplified setting reveal that VSL's nonlinearities may lead to considerable loss of assimilation skill, as compared to the utilization of a time-averaged (TA) linear observation operator. In order to understand this undesired effect, we embed VSL's formulation into the framework of fuzzy logic (FL) theory, which thereby exposes multiple representations of the principle of limiting factors. DA experiments employing three alternative growth rate functions disclose a strong link between the lack of smoothness of the growth rate function and the loss of optimality in the estimate of the TA state. Accordingly, VSL's performance as observation operator can be enhanced by resorting to smoother FL representations of the principle of limiting factors. This finding fosters new interpretations of tree-ring-growth limitation processes.

  15. Continuing upward trend in Mt Read Huon pine ring widths - Temperature or divergence?

    NASA Astrophysics Data System (ADS)

    Allen, K. J.; Cook, E. R.; Buckley, B. M.; Larsen, S. H.; Drew, D. M.; Downes, G. M.; Francey, R. J.; Peterson, M. J.; Baker, P. J.

    2014-10-01

    To date, no attempt has been made to assess the presence or otherwise of the “Divergence Problem” (DP) in existing multi-millennial Southern Hemisphere tree-ring chronologies. We have updated the iconic Mt Read Huon pine chronology from Tasmania, southeastern Australia, to now include the warmest decade on record, AD 2000-2010, and used the Kalman Filter (KF) to examine it for signs of divergence against four different temperature series available for the region. Ring-width growth for the past two decades is statistically unprecedented for the past 1048 years. Although we have identified a decoupling between temperature and growth in the past two decades, the relationship between some of the temperature records and growth has varied over time since the start of instrumental records. Rather than the special case of ‘divergence', we have identified a more general time-dependence between growth and temperature over the last 100 years. This time-dependence appears particularly problematic at interdecadal time scales. Due to the time-dependent relationships, and uncertainties related to the climate data, the use of any of the individual temperature series examined here potentially complicates temperature reconstruction. Some of the uncertainty in the climate data may be associated with changing climatic conditions, such as the intensification of the sub-tropical ridge (STR) and its impact on the frequency of anticyclonic conditions over the Mt Read site. Increased growth at the site, particularly in the last decade, over and above what would be expected based on a linear temperature model alone, may be consistent with a number of hypotheses. Existing uncertainties in the climate data need to be resolved and independent physiological information obtained before a range of hypotheses for this increased growth can be effectively evaluated.

  16. Chronomics of climatic variations of tree ring width

    NASA Astrophysics Data System (ADS)

    Otsuka, K.; Cornélissen, G.; Halberg, F.

    2010-12-01

    Variations in the average annual tree rings of 11 sequoia trees for 2189 years are studied. The power spectrum of tree ring variations, calculated by the Maximum Entropy Method (MEM), is power-law in character with the coefficient β close to -1.00, suggesting the fractal character of the considered time series. The calculations of the coefficient β in a 200-year sliding window showed that this coefficient rapidly drops to zero or very small positive values, indicating a break in the fractal structure in some intervals. We identified seven such episodes, two (the latest) of which correspond to Spörer and Maunder solar minima. The other five episodes, which occurred around 100 BC and 500, 700, 820, and 880 AD, i.e., before regular sunspot observations, may also correspond to climate changes. By combining methods aimed at identifying the specific spectral components, such as the Schwabe cycle and behavior of the 1/ f dependence as a chaos characteristic, the chronobiologic (chronomics) approach can be used to study the global climatic processes—such as cycles of about 500 years—bearing on global warming.

  17. Towards a common methodology to simulate tree mortality based on ring-width data

    NASA Astrophysics Data System (ADS)

    Cailleret, Maxime; Bigler, Christof; Bugmann, Harald; Davi, Hendrik; Minunno, Francesco; Peltoniemi, Mikko; Martínez-Vilalta, Jordi

    2015-04-01

    Individual mortality is a key process of population and community dynamics, especially for long-lived species such as trees. As the rates of vegetation background mortality and of massive diebacks accelerated during the last decades and would continue in the future due to rising temperature and increasing drought, there is a growing demand of early warning signals that announce that the likelihood of death is very high. If physiological indicators have a high potential to predict tree mortality, their development requires an intensive tree monitoring which cannot be currently done on a representative sample of a population and on several species. An easier approach is to use radial growth data such as tree ring-widths measurements. During the last decades, an increasing number of studies aimed to derive these growth-mortality functions. However, as they followed different approaches concerning the choice of the sampling strategy (number of dead and living trees), of the type of growth explanatory variables (growth level, growth trend variables…), and of the length of the time-window (number of rings before death) used to calculate them, it makes difficult to compare results among studies and a subsequent biological interpretation. We detailed a new methodology for assessing reliable tree-ring based growth-mortality relationships using binomial logistic regression models. As examples we used published tree-ring datasets from Abies alba growing in 13 different sites, and from Nothofagus dombeyi and Quercus petraea located in one single site. Our first approach, based on constant samplings, aims to (1) assess the dependency of growth-mortality relationships on the statistical sampling scheme used; (2) determine the best length of the time-window used to calculate each growth variable; and (3) reveal the presence of intra-specific shifts in growth-mortality relationships. We also followed a Bayesian approach to build the best multi-variable logistic model considering

  18. Development of narrow width type oil control ring for motorcycle engine

    SciTech Connect

    Tateishi, Yukio; Fujimura, Kazuhiro; Ishihara, Katsushi; Watanabe, Masanor

    1995-12-31

    The reduction of piston ring friction forces, which account for high percentages of the total engine friction loss, is vital for the simultaneous attainments of lower fuel consumption, higher engine power and speed. The authors et al. noted a three-piece type oil control ring in this study, and strived for the development of an oil control ring with a narrow width and a low tangential force. A new three-piece, type oil control ring with a small tolerance on tangential force and a width of 1.2 to 1.5 mm has been successfully developed by studying the effect of such a ring on the lubricating oil consumption, while providing a spring function by press-forming a wire rod having a particular sectional shape.

  19. Climate reconstructions from tree-ring widths for the last 850 years in Northern Poland

    NASA Astrophysics Data System (ADS)

    Heinrich, Ingo; Knorr, Antje; Heußner, Karl-Uwe; Wazny, Tomasz; Slowinski, Michal; Helle, Gerhard; Simard, Sonia; Scharnweber, Tobias; Buras, Allan; Beck, Wolfgang; Wilmking, Martin; Brauer, Achim

    2015-04-01

    Tree-ring based temperature reconstructions form the scientific backbone of the current debate over global change, and they are the major part of the palaeo data base used for the IPCC report. However, long temperature reconstructions derived from temperate lowland trees growing well within their distributional limits in central Europe are not part of the IPCC report, which is an essential gap in the international data base. It appears that dendroclimatological analysis at temperate lowland sites was so far difficult to perform mainly for three reasons: diffuse climate-growth relationships, the lack of long chronologies due to absence of sufficient numbers of long-living trees and the potential loss of low-frequency signals due to the short length of the sample segments. We present two robust multi-centennial reconstructions of winter temperatures and summer precipitation based on pine and oak tree-ring widths chronologies from northern Poland, where so far no long tree-ring based reconstructions were available. We compared the new records with global, hemispherical and regional reconstructions, and found good agreement with some of them. In comparison, the winter temperature of our reconstruction, however, did not indicate any modern warming nor did the summer precipitation reconstruction suggest any modern 20th century changes. In a second step, we measured cell structures and developed chronologies of parameters such as cell wall thickness and cell lumen area. We used our new method (Liang et al. 2013a,b) applying confocal laser scanning microscopy to increment core surfaces for efficient histometric analyses. We focused on samples covering the last century because meteorological data necessary for calibration studies were available for direct comparisons. It was demonstrated that the correlations with climate were strong and different from those found for tree-ring widths (e.g., N-Poland oak-vessel-lumen-area-chronology with previous September-to-December mean

  20. North Patagonia climate over the last millennium inferred from variations in tree-ring width and isotopic composition

    NASA Astrophysics Data System (ADS)

    Lavergne, Aliénor; Villalba, Ricardo; Daux, Valérie

    2014-05-01

    To disentangle natural variability from man-induced climate changes, current climatic trends should be placed in a longer perspective. Tree-rings provide a wealth of information on past climates with high-resolution records covering up to thousands years. Recent tree-ring studies have highlighted the divergence phenomenon in Northern Hemisphere forests. At some temperature-limited northern sites, tree growth responses to climate during recent decades have changed, raising concerns about the quality of historical climate reconstructions based on tree-ring widths. This shift in the eco-physiological response of trees to climate has not yet been documented in the Southern Hemisphere. The aim of this study is to present the tree-ring evolution over the last centuries in northern Patagonia (southern South America; 41° 10'S-71° 50'W) in order to assess 1) divergence in tree-growth response to climate in recent decades, and 2) the potential of tree-ring parameters (width and δ18O) to reconstruct temperature and atmospheric circulation patterns such as the Southern Annular Mode (SAM). Based on quality and extent, instrumental temperature records across North Patagonia (39° -41° S) were selected for comparison with tree-ring records. Detection and correction of series inhomogeneities were conducted using HOMER software. A set of homogenized temperature data was developed for the period 1901-2013. Increment-borer samples from Fitzroya cupressoides and Nothofagus pumilio were collected along the regional precipitation gradient from the wet Valdivian rainforest to the mesic Patagonian forests during the austral summer of 2013. Six sampling sites (2 for Fitzroya, 4 for Nothofagus) along the gradient were established to maximize differences in tree-growth responses to climate and to assess the effect of precipitation on the responses. More than 500 cores were cross-dated, detrended and indexed. Composite tree-ring index (TRI) chronologies of F. cupressoides and N. pumilio

  1. Domain wall width of lithium niobate poled during growth

    NASA Astrophysics Data System (ADS)

    Brooks, R.; Townsend, P. D.; Hole, D. E.; Callejo, D.; Bermúdez, V.; Diéguez, E.

    2003-04-01

    Good quality crystals of periodically poled lithium niobate can be generated directly during growth. However, the temperature gradients at the zone boundaries define the width of the regions where the polarity is reversed. Hence, the region influenced the domain transition may be a significant fraction of the overall poling period for material poled during growth. Evidence for the scale of this feature is reported both by chemical etching and by the less common method of ion beam luminescence and the `domain wall' width approximately 1 mum for these analyses. The influence of the reversal region may differ for alternative techniques but the relevance to device design for second harmonic generation is noted.

  2. Do coralline red algal growth increment widths archive paleoenvironmental information?

    NASA Astrophysics Data System (ADS)

    Halfar, J.; Winsborough, C.; Omar, A.; Hetzinger, S.; Steneck, R. S.; Lebednik, P. A.

    2009-04-01

    Over the past decade coralline red algae have received increased attention as archives of paleoclimate information. Encrusting coralline red algae, which deposit annual growth increments in a High-Mg calcite skeleton, are amongst the longest-lived marine organisms. In fact, a live-collected plant has recently been shown to have lived for at least 850 years based on radiometric dating. While a number of investigations have successfully utilized geochemical information obtained from coralline red algal skeletons to reconstruct climate, no study has yet examined the potential of using growth increment widths as a proxy for past water temperatures. Here we explore the relationship between growth and environmental parameters in Clathromorphum nereostratum from the Bering Sea. A 120-year long annual growth record shows a significant but weak correlation to regional sea surface temperature data (r=0.24), which requires much of the observed annual growth increment width variability to be explained by other factors. We therefore examined coralline red algal growth for a 20-year period in multiple specimens collected along a depth transect from 10 to 35 m water depth. Results demonstrate a significant decrease in average annual growth increment widths with increasing water depth. Due to intense wind-induced mixing in the region the upper water column exhibits near uniform temperatures and salinities, leaving the decreasing amount of light with depth as the dominant variable influencing vertical extension. This was further tested by examining specimens collected at 10 m water depth at different locations receiving distinct amounts of shading provided by 100%, 50%, and 0% kelp canopy coverage. Results indicate a negative relationship between percent kelp canopy coverage and annual growth increment width. It can therefore be concluded that the dominant factor controlling vertical growth in C. nereostratum is light, with temperature only accounting for a small portion of growth

  3. Teasing Foggy Memories out of Pines on the California Channel Islands Using Tree-Ring Width and Stable Isotope Approaches

    NASA Astrophysics Data System (ADS)

    Williams, A. P.; Still, C. J.; Fischer, D. T.; Leavitt, S. W.

    2006-12-01

    The coast of California is home to many rare, endemic conifers and other plants that are not well adapted to the Mediterranean climate that prevails across most of the state. It has long been suggested that coastal pines survived the early-Pleistocene transition to a warmer and drier environment because they benefit from frequent fog and low stratus clouds that provide much needed water inputs and shading during the rainless summer. Here, we report evidence for the importance of this summer cloudiness to Torrey pines (Pinus torreyana) growing on Santa Rosa Island in Channel Islands National Park. We developed a tree-ring width chronology and quantified the relative importance of winter/spring precipitation and summer fog by comparing ring widths to nearby rainfall records and airport cloud-ceiling height data. While winter/spring precipitation explains most of the variation in annual tree-ring width (R2 = 0.592), the frequency of summertime fog correlated significantly and positively with annual ring width for 52 years of available fog data when the effect of winter/spring precipitation was removed (R2 = 0.118). The correlation between fog frequency and ring width decreased sharply when the range of possible cloud-ceiling heights deviated from the habitat range of the Torrey pine stand, emphasizing the importance of direct cloud immersion to these pines. In addition, the relationship between fog frequency and ring width was strongest in the 26 years that had enough winter/spring rainfall to maintain above-average soil moisture throughout the dry summer months (R2 = 0.312). This suggests that Torrey pines have an adaptive growing season length and that summer fog-water inputs are supplemental but not substantial enough to sustain tree growth independently. It may also be suggested that when summer growth does occur, the frequency of summer fog and stratus may govern growing season length. This made a "fog signal" difficult to detect in the stable isotope (carbon and

  4. Alternative standardization approaches to improving streamflow reconstructions with ring-width indices of riparian trees

    USGS Publications Warehouse

    Meko, David M; Friedman, Jonathan M.; Touchan, Ramzi; Edmondson, Jesse R.; Griffin, Eleanor R.; Scott, Julian A.

    2015-01-01

    Old, multi-aged populations of riparian trees provide an opportunity to improve reconstructions of streamflow. Here, ring widths of 394 plains cottonwood (Populus deltoids, ssp. monilifera) trees in the North Unit of Theodore Roosevelt National Park, North Dakota, are used to reconstruct streamflow along the Little Missouri River (LMR), North Dakota, US. Different versions of the cottonwood chronology are developed by (1) age-curve standardization (ACS), using age-stratified samples and a single estimated curve of ring width against estimated ring age, and (2) time-curve standardization (TCS), using a subset of longer ring-width series individually detrended with cubic smoothing splines of width against year. The cottonwood chronologies are combined with the first principal component of four upland conifer chronologies developed by conventional methods to investigate the possible value of riparian tree-ring chronologies for streamflow reconstruction of the LMR. Regression modeling indicates that the statistical signal for flow is stronger in the riparian cottonwood than in the upland chronologies. The flow signal from cottonwood complements rather than repeats the signal from upland conifers and is especially strong in young trees (e.g. 5–35 years). Reconstructions using a combination of cottonwoods and upland conifers are found to explain more than 50% of the variance of LMR flow over a 1935–1990 calibration period and to yield reconstruction of flow to 1658. The low-frequency component of reconstructed flow is sensitive to the choice of standardization method for the cottonwood. In contrast to the TCS version, the ACS reconstruction features persistent low flows in the 19th century. Results demonstrate the value to streamflow reconstruction of riparian cottonwood and suggest that more studies are needed to exploit the low-frequency streamflow signal in densely sampled age-stratified stands of riparian trees.

  5. 400+ Years of ENSO-like Climate Cyclicity from Tree Ring Width-Data, Wind River Range, Wyoming, USA.

    NASA Astrophysics Data System (ADS)

    Dahms, D. E.; Richards, D.; Pease, P.

    2014-12-01

    Spectral analysis of detrended ring-width data from a series of +400-year-old Douglas Firs on the SE flank of the Wind River Range indicates that tree growth from 1589-to-2013 shows a 2.5-to-4.5-year cyclicity (99%). This is within the limits of the generally accepted ~2-7 year ENSO cyclicity of the western Pacific. Our results also show a 16-year frequency (95%) suggesting possible additional influence from the Pacific Decadal Oscillation (PDO). Ring-widths here are most closely correlated to soil moisture conditions through the interaction(s) of abundant winter snowpack, summer rainfall, and average May-August temperatures during the 424-years from 1589-2013. Nearby climate records from the 1948-2013 period show that more favorable growth conditions exist here (higher snowpack+summer precipitation) during the El Niño cycle of ENSO. Our results fill a gap in knowledge of ENSO-like teleconnections during the Late Holocene that exists for the southern region of the Greater Yellowstone Ecosystem.

  6. Moisture-sensitive tree-ring widths from the Craters of the Moon lava-complex in east central, Idaho

    NASA Astrophysics Data System (ADS)

    Crawford, C. J.; Kipfmueller, K. F.; St George, S.

    2011-12-01

    Craters of the Moon (COM) National Monument is a basaltic volcanic complex on the eastern Snake River Plain that has formed over eight eruptive periods during the Holocene. Since the last eruption, limber pine (Pinus flexilis) and Douglas-fir (Pseudotsuga menziesii Mirb Franco.) have established on lava flows and ancient weathered cinder cones. These rare long-lived trees have survived for 400 - 1000 years on well-drained porous rock, inviting the possibility that tree-ring widths will show elevated moisture sensitivity. Four tree-ring records have been constructed from living trees and remnant wood that include limber pine total ring-width (937-2009 AD), Douglas-fir total ring-width, and partial earlywood and latewood widths (1468-2009 AD). During 1550-2009 AD, the covariance between records is moderately significant (0.31-0.34, p<0.01) for standard chronologies, but residual chronologies show little association (0.05-0.08). Monte-Carlo correlations between tree-ring widths and instrumental climate data (1930-2009) indicate that annual precipitation (prior Jun. - May) is correlated (p<0.01) with limber pine and Douglas-fir standard ring-width, and seasonal precipitation is correlated (p<0.01) with residual limber pine ring-width (prior Jul. - prior Dec.) and residual Douglas-fir earlywood width (Jan. - Jun). Because cool-season precipitation dominates the annual hydrological budget for the COM region, total ring-width persistence is primarily tuned to total annual precipitation while residual variance appears to reflect seasonal differences between the amount of prior fall - winter and winter - spring season moisture. So far, COM tree-ring records seem well suited as candidate predictors for paleoclimate reconstructions of not only annual precipitation, but also seasonally partitioned precipitation at interannual-decadal timescales.

  7. Boreal temperature variability inferred from maximum latewood density and tree-ring width data, Wrangell Mountain region, Alaska

    NASA Astrophysics Data System (ADS)

    Davi, Nicole K.; Jacoby, Gordon C.; Wiles, Gregory C.

    2003-11-01

    Variations in both width and density of annual rings from a network of tree chronologies were used to develop high-resolution proxies to extend the climate record in the Wrangell Mountain region of Alaska. We developed a warm-season (July-September) temperature reconstruction that spans A.D. 1593-1992 based on the first eigenvector from principal component analysis of six maximum latewood density (MXD) chronologies. The climate/tree-growth model accounts for 51% of the temperature variance from 1958 to 1992 and shows cold in the late 1600s-early 1700s followed by a warmer period, cooling in the late 1700s-early 1800s, and warming in the 20th century. The 20th century is the warmest of the past four centuries. Several severely cold warm-seasons coincide with major volcanic eruptions. The first eigenvector from a ring-width (RW) network, based on nine chronologies from the Wrangell Mountain region (A.D. 1550-1970), is correlated positively with both reconstructed and recorded Northern Hemisphere temperatures. RW shows a temporal history similar to that of MXD by increased growth (warmer) and decreased growth (cooler) intervals and trends. After around 1970 the RW series show a decrease in growth, while station data show continued warming, which may be related to increasing moisture stress or other factors. Both the temperature history based on MXD and the growth trends from the RW series are consistent with well-dated glacier fluctuations in the Wrangell Mountains and some of the temperature variations also correspond to variations in solar activity.

  8. [Vertical variability of Pinus sylvestris var. mongolica tree ring delta13C and its relationship with tree ring width in northern Daxing' an Mountains of Northeast China].

    PubMed

    Shang, Zhi-Yuan; Wang, Jian; Zhang, Wen; Li, Yan-Yan; Cui, Ming-Xing; Chen, Zhen-Ju; Zhao, Xing-Yun

    2013-01-01

    A measurement was made on the vertical direction tree ring stable carbon isotope ratio (delta13C) and tree ring width of Pinus sylvestris var. mongolica in northern Daxing' an Mountains of Northeast China, with the relationship between the vertical direction variations of the tree ring delta13C and tree ring width analyzed. In the whole ring of xylem, earlywood (EW) and bark endodermis, the delta13C all exhibited an increasing trend from the top to the base at first, with the maximum at the bottom of tree crown, and then, decreased rapidly to the minimum downward. The EW and late-wood (LW) had an increasing ratio of average tree ring width from the base to the top. The average annual sequence of the delta13C in vertical direction had an obvious reverse correspondence with the average annual sequence of tree ring width, and had a trend comparatively in line with the average annual sequence of the tree ring width ratio of EW to LW above tree crown. The variance analysis showed that there existed significant differences in the sequences of tree ring delta13C and ring width in vertical direction, and the magnitude of vertical delta13C variability was basically the same as that of the inter-annual delta13C variability. The year-to-year variation trend of the vertical delta13C sequence was approximately identical. For each sample, the delta13C sequence at the same heights was negatively correlated with the ring width sequence, but the statistical significance differed with tree height. PMID:23717983

  9. Optical tweezers assisted imaging of the Z-ring in Escherichia coli: measuring its radial width

    NASA Astrophysics Data System (ADS)

    Carmon, G.; Kumar, P.; Feingold, M.

    2014-01-01

    Using single-beam, oscillating optical tweezers we can trap and rotate rod-shaped bacterial cells with respect to the optical axis. This technique allows imaging fluorescently labeled three-dimensional sub-cellular structures from different, optimized viewpoints. To illustrate our method we measure D, the radial width of the Z-ring in unconstricted Escherichia coli. We use cells that express FtsZ-GFP and have their cytoplasmic membrane stained with FM4-64. In a vertically oriented cell, both the Z-ring and the cytoplasmic membrane images appear as symmetric circular structures that lend themselves to quantitative analysis. We found that D ≅ 100 nm, much larger than expected.

  10. Multicentury Reconstruction of Precipitations (1300-2014) in Eastern Canada from Tree-Ring Width and Carbon and Oxygen Isotopes

    NASA Astrophysics Data System (ADS)

    Giguère, Claudie; Boucher, Étienne; Bergeron, Yves

    2016-04-01

    Tree ring series enabling long hydroclimatic reconstructions are scarce in Northeastern America, mostly because most boreal species are rather thermo-dependant. Here we propose a new multi-proxy analysis (tree-ring, δ13C and δ18O) from one of the oldest Thuja occidentalis population in NE America (lake Duparquet, Quebec). These rare precipitation-sensitive, long-living trees (> 800 years) grow on xeric rocky shores and their potential for paleo-hydroclimatic reconstructions (based on ring widths solely) was previously assessed. The objectives of this study are twofold i) to strengthen the hydroclimatic signal of this long tree-ring chronology by adding analysis of stable isotope ratios (δ13C and δ18O) and ii) to reconstruct summer precipitation back to 1300 AD, which will represent, by far, the longest high-resolution hydroclimatic reconstruction in this region. A tree-ring chronology was constructed from 61 trees sampled in standing position. Eleven trees were also sampled to produce pooled carbon and oxygen isotope chronologies (annually resolved) with a replication of five to six trees per year. Signal analysis (correlation between climatic data and proxy values) confirms that growth is positively influenced by spring precipitations (May-June), while δ13C is negatively correlated to summer precipitation (June to August) and positively to June temperature. Adding δ18O analysis will strengthen the signal even more, since wood cellulose should be enriched in δ18O when high evapotranspiration conditions prevail. Based on a multi-proxy approach, a summer precipitation reconstruction was developed and compared to other temperature reconstructions from this region as well as to southernmost hydroclimatic reconstructions (e.g. Cook et al). A preliminary analysis of external and internal forcing is proposed in conclusion.

  11. Solar and climate signal records in tree ring width from Chile (AD 1587 1994)

    NASA Astrophysics Data System (ADS)

    Rodolfo Rigozo, Nivaor; Roger Nordemann, Daniel Jean; Evangelista da Silva, Heitor; Pereira de Souza Echer, Mariza; Echer, Ezequiel

    2007-01-01

    Tree growth rings represent an important natural record of past climate variations and solar activity effects registered on them. We performed in this study a wavelet analysis of tree ring samples of Pilgerodendron cupressoides species, from Glaciar Pio XI (Lat: 49°12'S; 74°55'W; Alt: 25 m), Chile. We obtained an average chronology of about 400 years from these trees. The 11-yr solar cycle was present during the whole period in tree ring data, being more intense during Maunder minimum (1645-1715). The short-term periods, around 2-7 yr, that were found are more likely associated with ENSO effects. Further, we found significant periods around 52 and 80-100 yr. These periodicities are coincident with the fourth harmonic (52 yr) of the Suess cycle (208 yr) and Gleissberg (˜80-100 yr) solar cycles. Therefore, the present analysis shows evidence of solar activity effect/modulation on climatic conditions that affect tree ring growth. Although we cannot say with the present analysis if this effect is on local, regional or global climate, these results add evidence to an important role of solar activity over terrestrial climate over the past ˜400 yr.

  12. Inferring long-term carbon sequestration from tree rings at Harvard Forest: A calibration approach using tree ring widths and geochemistry / flux tower data

    NASA Astrophysics Data System (ADS)

    Belmecheri, S.; Maxwell, S.; Davis, K. J.; Alan, T. H.

    2012-12-01

    Improving the prediction skill of terrestrial carbon cycle models is important for reducing the uncertainties in global carbon cycle and climate projections. Additional evaluation and calibration of carbon models is required, using both observations and long-term proxy-derived data. Centennial-length data could be obtained from tree-rings archives that provide long continuous series of past forest growth changes with accurate annual resolution. Here we present results from a study conducted at Harvard Forest (Petersham, Massachusetts). The study examines the potential relationship between δ13C in dominant trees and GPP and/or NEE measured by the Harvard Forest flux tower (1992-2010). We have analyzed the δ13C composition of late wood-cellulose over the last 18 years from eastern hemlock (Tsuga canadensis) and northern red oak (Quercus rubra) trees growing in the flux tower footprint. δ13C values, corrected for the declining trend of atmospheric δ13C, show a decreasing trend from 1992 to 2010 and therefore a significant increase in discrimination (Δ). The intra-cellular CO2 (Ci) calculated from Δ shows a significant increase for both tree species and follows the same rate of atmospheric CO2 (Ca) increase (Ci/Ca increases). Interestingly, the net Ci and Δ increase observed for both species did not result in an increase of the iWUE. Ci/Ca is strongly related to the growing season Palmer Drought Severity Index (PDSI) for both species thus indicating a significant relationship between soil moisture conditions and stomatal conductance. The Ci trend is interpreted as a result of higher CO2 assimilation in response to increasing soil moisture allowing a longer stomata opening and therefore stimulating tree growth. This interpretation is consistent with the observed increase in GPP and the strengthening of the carbon sink (more negative NEE). Additionally, the decadal trends of basal area increment (BAI) calculated from tree-ring widths exhibit a positive trend over

  13. Ensemble empirical mode decomposition as a tool of lake sediments and tree-ring width chronologies investigation

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Dmitriy; Mordvinov, Alexandr; Kalugin, Ivan; Darin, Andrey; Myglan, Vladimir

    2014-05-01

    A method named ensemble empirical mode decomposition (EEMD) was used to analyse different paleoclimatic data such as non-varved lake sediments of the Teletskoye lake and long tree-ring width chronologies from the Altai region (Altai Mountains, South Siberia, Russia) in the late Holocene (2000 years). Core of the bottom sediments from the Teletskoe lake (Altai Mountains) were investigated using scanning X-ray fluorescent analysis method with synchrotron radiation (spatial resolution is 0.1 mm). Low-frequency signals (modes) were extracted from both paleoarchives and shown: ~ 60, ~ 100, ~ 200, ~ 300-500 and ~1000-year cycles in the Teletskoye lake; ~ 25-33, ~ 50-60, ~100- 200, ~ 300 and ~ 1000 year cycles in tree-ring width chronologies. A common 200-year cycle was found in both archives. Also EEMD method was used to analyse a solar-activity during late Holocene. The magnetic solar activity well associated with tree-ring width chronologies. Changes of the tree-ring width chronology on the millennial time scale coincide with similar changes of the solar activity in the Holocene. Stable relationships between solar activity and climate characteristics are found on 100-200 years time scales (Glaysberg and Suess cycles). The magnetic solar activity and paleotemperature changes are observed as solar-terrestrial relations on a large time scale. It is indicate that the temperature increase in the 19-20 centuries is largely due to the impact of solar activity on the Earth's climate system. Solar-terrestrial relations analysis shown common 200-year cycle in all presented paleoarchives. The study was funded by: Interdisciplinary Integration Project SB RAS # 34 and grants # 13-05-00620 from the Russian Foundation for Basic Research. Key words: ensemble empirical mode decomposition (EEMD), lake sediments, tree-ring width chronologies, solar-terrestrial relations

  14. Two centuries temperature variations over subtropical southeast China inferred from Pinus taiwanensis Hayata tree-ring width

    NASA Astrophysics Data System (ADS)

    Cai, QiuFang; Liu, Yu

    2016-05-01

    High-resolution long-term temperature reconstructions in subtropical southeast China (SSC) are very scarce, yet indispensable for the comprehensive understanding of climate change in China, even in East Asia. We reconstructed the first previous growth-season temperature in the Sanqingshan Mountains (SQS), southeast China since 1806 based on tree-ring width data. The reconstruction accounts for 56.4 % of the total variance in the instrumental record over 1954-2009. Unlike the Northern Hemispheric warming during recent two centuries, the reconstruction captured a slowly cooling trend from 1806 to 1980, followed by a rapid warming afterward. 2003-2009 was the warmest period in the reconstruction. 1970-2000 was colder than the last stage of the Little Ice Age (LIA). Most of the warm and cold periods in this reconstruction could be found in the tree-ring based temperature reconstructions of vicinity area, indicating that the temperature variations in SSC were almost synchronous at least at decadal scale. This regional coherence of temperature variation was further confirmed by the spatial correlation patterns with the CRU TS3.22 grid dataset. A strong positive relationship between the temperature over SQS region and sea surface temperature (SST) over the North Pacific Ocean (NP) has been noted, suggesting that SST variations over NP and the related Pacific Decadal Oscillation significantly influenced the temperature variability over SSC. To better understand the climate variability during the LIA and the regional differences in temperature variations over SQS and northern Hemisphere, long data sets from more diverse areas of southern China are needed.

  15. Occurrence of annual growth rings in Rhizophora mangle in a region with low climate seasonality.

    PubMed

    Souza, Brunna T; Estrada, Gustavo C D; Soares, Mário L G; Callado, Cátia H

    2016-01-01

    The formation of annual growth rings has been confirmed for several mangrove species in the last decade, among which is the Rhizophora mangle. However, the record of annual rings for this species was made in a region with high hydric seasonality, a widely recognized induction factor of annual rings in tropical species. In this sense, the present study aimed to verify the occurrence of annual growth rings in R. mangle in the mangroves of Guaratiba (Rio de Janeiro, Southeastern Brazil), a region with low hydric seasonality. For this purpose, the crossdating technique was applied in ten trees collected with known age (seven years). The growth rings are characterized by alternating layers of low vessel density (earlywood) and high vessel density (latewood). Multiple regression analysis indicated that growth rings width variation is driven by precipitation, water surplus, water deficit and water storage. Crossdating analysis confirmed the existence of annual growth rings in the R. mangle in Guaratiba. This discovery in a region with low hydric seasonality increases the dendrocronological potential of this species and suggests the importance of biological factors (eg. phenological behavior) as complementary inductors for the formation of growth rings in this species. PMID:27142552

  16. Interpretation of tree-ring data with a model for primary production, carbon allocation and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Wang, H.; Harrison, S. P.; Prentice, I. C.

    2013-12-01

    We present a simple, generic model of annual tree growth, called ';T'. This model accepts input from a generic light-use efficiency model which is known to provide good simulations of terrestrial carbon exchange. The light-use efficiency model provides values for Gross Primary Production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport-tissue, and fine-root production and respiration, in such a way as to satisfy well-understood dimensional relationships. The result is a model that can represent both ontogenetic effects and the effects of environmental variations and trends on growth. The model has been applied to simulate ring-width series from multiple individual trees in temperature- and drought-limited contexts. Each tree is initialized at its actual diameter at the time when local climate records started. These records are used to drive the trees' subsequent growth. Realistic simulations of the pattern of interannual variability of ring-width are generated, and shown to relate statistically to climate. An upward trend in ring-width during 1958-2007 is shown to be present in the primary observations, and in the simulations; but not in the standard, detrended ring-width series. This approach combines two modelling approaches previously developed in the global carbon cycle and forest science literature respectively. Neither has been widely applied in the context of tree-ring based climate reconstruction. This combination of methods offers promise, however, because it could provide a way to sidestep several known problems. These include: reliance on correlations for the interpretation of ring-width variations in terms of climate; the necessity of detrending using empirical functions (which can remove trends caused by variations in the environment as well as those that are ontogenetic); and the difficulty of assessing effects of extrinsic, non

  17. Solar and Climate Variation Relationships Analyzed from Chile Tree Ring Width Time Series (1587 - 1994 A.D.)

    NASA Astrophysics Data System (ADS)

    Rigozo, Nr; Nordemann, Djr; Faria, Hh; Echer, E.; Vieira, Lea; Prestes, A.

    This work presents a study of the relations between solar and climate variations during the last four centuries by spectral analysis of tree ring index and sunspot number time series. Trees used for this study were Pilgerodendron cupressoides from Glaciar Pio XI, in Chile. The spectral analysis of tree ring index shows that 11, 22 and 80 year periodicities of the solar cycle were present in this tree ring data with 0.95 confidence level. This result suggests a solar modulation of climate variations, as recorded by the tree ring growth. Short-term variations, between 2 - 7 years, are also present in tree ring data. Therefore spectral analysis clearly shows that both, solar and climate factors, are recorded in the tree ring data.

  18. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak (Quercus robur) in northern Poland?

    NASA Astrophysics Data System (ADS)

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P.

    2015-11-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon.

  19. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak ( Quercus robur) in northern Poland?

    NASA Astrophysics Data System (ADS)

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P.

    2016-08-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon.

  20. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak (Quercus robur) in northern Poland?

    PubMed

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P

    2016-08-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon. PMID:26607274

  1. Multi-proxy approaches to isolating low-frequency climate signals from tree-ring δ13C, δ18O and ring-widths

    NASA Astrophysics Data System (ADS)

    Voelker, S. L.; Johnstone, J. A.; Roden, J. S.; Dawson, T. E.

    2013-12-01

    Tree-ring stable isotope records have been increasingly used as climate proxies and have often improved the coherence of climate signals compared to ring-width variability. Here we explore the potential for combining tree ring 13C, 18O and ring-width data to isolate low-frequency climate variation from 1) bur oak trees from mid-continental USA and 2) coastal California redwood trees. For modern mid-continental oaks, Δ13C [carbon isotope discrimination] and Δ18O [isotopic enrichment above source water] are negatively correlated across space and time, conditions representative of the bioclimatic envelope for this species. Correlations with the vapor pressure deficit at the growing season maximum temperature (VPDmax) were greatest for the dual isotopic signal as compared to Δ13C or Δ18O alone (r = 0.79, 0.69 and 0.75, respectively). As applied to 59 sub-fossil oak logs [14C-dated to 9.97-13.64k Cal yrs BP] from Missouri, USA, this dual isotope signal indicates that the Pleistocene-Holocene transition was characterized by an abrupt transition near the end of the Younger-Dryas period from a cold, wet and relatively stable growing season climate to a more variable early Holocene climate characterized by periods of greater growing season VPD and maximum temperatures. Our data further suggest that correlations between Δ13C or Δ18O and ring-width chronologies may provide a record of decadal to multi-decadal variability in VPDmax. For coastal California redwoods, from 1951-2003, we demonstrate drastic differences in both sign and magnitude of 11-year running correlations between northern California regional Δ13C or δ18O chronologies for 'middlewood' or 'latewood' (MW or LW) and a regional ring-width chronology. Comparisons of trends in these correlations to 11-year means of Pacific Decadal Oscillation index (PDO, May-September) show similarities with MW or LW Δ13C (r = 0.70 and 0.53, respectively) and stronger correspondence with inverted MW and LW δ18O (r = 0

  2. Using Novel Approaches in Process-Based Modeling for Interpreting Inter-Annual Variability in Tree Ring Widths, Wood Density Profiles, and Cellulose Isotopic Ratios

    NASA Astrophysics Data System (ADS)

    Friend, A. D.; Babst, F.; Belmecheri, S.; Frank, D. C.; Hacket Pain, A. J.; Hayat, A.; Poulter, B.; Rademacher, T. T.; Trouet, V.

    2015-12-01

    Time series annual of tree ring width, density variation, and oxygen and carbon isotopic compositions have the potential to substantially increase our knowledge of forest responses to environmental variation. However, their interpretation is not straightforward due to the simultaneous influences of a number of confounding factors, including carry-over effects from previous years, variable resource allocation with size, age, and canopy position, species-specific physiologies, and complex interactions between forcings such as temperature, soil moisture, and atmospheric CO2. Here we attempt to tease these factors apart and so substantially improve the interpretability of tree ring archives through the construction and application of novel approaches within a process-based model of individual tree growth. The model incorporates descriptions of xylem cell division, expansion, and secondary wall thickening, apical and lateral meristem activities with internal controls from internal signals, internal carbon storage, and the dynamics of canopy photosynthesis, stomatal movements, evapotranspiration, canopy temperatures, and soil moisture. Alternative treatments of isotopic fractionation and growth controls are evaluated using measured datasets. We demonstrate how this new model approach can be used to assess the information contained in tree rings concerning the influence of increasing atmospheric CO2 over the past century on growth and water use efficiency at a range of sites.

  3. Multiple tree-ring chronologies (ring width, δ13C and δ18O) reveal dry and rainy season signals of rainfall in Indonesia

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Heinrich, Ingo; Neuwirth, Burkhard; Krusic, Paul J.; D'Arrigo, Rosanne D.; Karyanto, Oka; Helle, Gerhard

    2013-08-01

    Climatic hazards, such as severe droughts and floods, affect extensive areas across monsoon Asia and can have profound impacts on the populations of that region. The area surrounding Indonesia, including large portions of the eastern Indian Ocean and Java Sea, plays a key role in the global climate system because of the enormous heat and moisture exchange that occurs between the ocean and atmosphere there. Here, we evaluate the influence of rainfall variability on multiple tree-ring parameters of teak (Tectona grandis) trees growing in a lowland rain forest in Central Java (Indonesia). We assess the potential of, annually resolved, tree-ring width, stable carbon (δ13C) and oxygen (δ18O) isotope records to improve our understanding of the Asian monsoon variability. Climate response analysis with regional, monthly rainfall data reveals that all three tree-ring parameters are significantly correlated to rainfall, albeit during different monsoon seasons. Precipitation in the beginning of the rainy season (Sep-Nov) is important for tree-ring width, confirming previous studies. Compared to ring width, the stable isotope records possess a higher degree of common signal, especially during portions of the peak rainy season (δ13C: Dec-May; δ18O: Nov-Feb) and are negatively correlated to rainfall. In addition, tree-ring δ18O also responds positively to peak dry season rainfall, although the δ18O rainy season signal is stronger and more time-stable. The correlations of opposite sign reflect the distinct seasonal contrast of the δ18O signatures in rainfall (18OPre) during the dry (18O-enriched rain) and rainy (18O-depleted rain) seasons. This difference in 18OPre signal reflects the combination of two signals in the annual tree-ring δ18O record. Highly resolved intra-annual δ18O isotope analyses suggest that the signals of dry and rainy season can be distinguished clearly. Thereby reconstructions can improve our understanding of variations and trends of the

  4. Long-term summer sunshine/moisture stress reconstruction from tree-ring widths from Bosnia and Herzegovina

    NASA Astrophysics Data System (ADS)

    Poljanšek, S.; Ceglar, A.; Levanič, T.

    2013-01-01

    We present the first summer sunshine reconstruction from tree-ring data for the western part of the Balkan Peninsula. Summer sunshine is tightly connected with moisture stress in trees, because the moisture stress and therefore the width of annual tree-rings is under the influence of the direct and interactive effects of sunshine duration (temperature, precipitation, cloud cover and evapotranspiration). The reconstruction is based on a calibrated z-scored mean chronology, calculated from tree-ring width measurements from 7 representative black pine (Pinus nigra Arnold) sites in Bosnia and Herzegovina (BiH). A combined regression and scaling approach was used for the reconstruction of the summer sunshine. We found a significant negative correlation (r = -0.54, p < 0.0001) with mean June-July sunshine hours from Osijek meteorological station (Croatia). The developed model was used for reconstruction of summer sunshine for the time period 1660-2010. We identified extreme summer events and compared them to available documentary historical sources of drought, volcanic eruptions and other reconstructions from the broader region. All extreme summers with low sunshine hours (1712, 1810, 1815, 1843, 1899 and 1966) are connected with volcanic eruptions.

  5. Multiple tree-ring chronologies (ring width, δ13C and δ18O) reveal dry and rainy season signals in Indonesia

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Heinrich, Ingo; Neuwirth, Burkhard; Krusic, Paul; D`Arrigo, Rosanne; Karyanto, Oka; Helle, Gerhard

    2013-04-01

    The tropical Indonesian region plays a key role in the global climate system because of the enormous heat and moisture exchange between ocean and atmosphere in that area. Here, we evaluate the influence of rainfall variability on multiple tree-ring parameters of Teak (Tectona grandis) trees growing in a lowland rain forest in Central Java (Indonesia). Three, annually resolved, chronologies of tree-ring width, stable carbon (δ13C) and oxygen (δ18O) isotopes were developed for the twentieth century (1900-2007). Climate response analysis with regional rainfall data has revealed that all three tree-ring parameters are significantly sensitive to rainfall during different intervals of the seasonal monsoon pattern. The amount of rainfall at the beginning of the rainy season (Sep-Nov) is important for tree-ring width, confirming previous studies. The stable isotope records best represent slightly different sub-periods of the prime rainy season (δ13C: Dec-May; δ18O: Nov-Feb) with negative correlations. Tree-ring δ18O additionally responds well to peak dry season rainfall with positive correlation. The correlations of opposite sign reflect the distinct seasonal contrast of the δ18O signatures of rainfall during the dry (18O-enriched rain) and rainy (18O-depleted rain) seasons in conjunction with changing rainfall amount. Dry season periods with rainfall amounts above average have an exceptionally strong influence on tree-ring δ18O in years with below average rainy season rainfall. In such cases, the dry season signal reduces the signal strength of the prime rainy season in tree-ring δ18O. However, the rainy season signal is still strong and stable over the 20th century. Further, the δ18O record correlates with several ENSO events, supported by spectral analysis which reveals significant peaks on the 2-4 year band. Highly resolved intra-annual δ18O isotope analyses suggest that the signals of dry and rainy season can be distinguished clearly and demonstrate a new

  6. Spring temperatures in the far-western Nepal Himalaya since AD 1640 reconstructed from Picea smithiana tree-ring widths

    NASA Astrophysics Data System (ADS)

    Thapa, Udya Kuwar; Shah, Santosh K.; Gaire, Narayan Prasad; Bhuju, Dinesh Raj

    2015-10-01

    We developed a new, 422-year long tree-ring width chronology (spanning AD 1591-2012) from Picea smithiana (Wall.) Boiss in Khaptad National Park, which is located in the far-western Nepalese Himalaya. Seasonal correlation analysis revealed significant indirect relationship with spring temperature and lead to the reconstruction of March-May average temperature for the past 373 years (AD 1640-2012). The reconstruction was found significant based on validation statistics commonly used in tree-ring based climate reconstruction. Furthermore, it was validated through spatial correlation with gridded temperature data. This temperature reconstruction identified several periods of warming and cooling. The reconstruction did not show the significant pattern of cooling during the Little Ice Age but there were few cold episodes recorded. The spring temperature revealed relationship with different Sea Surface Temperature index over the equatorial Pacific Ocean, which showed linkages with climatic variability in a global scale.

  7. Narrow line-width single-longitudinal-mode fiber laser using silicon-on-insulator based micro-ring-resonator

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Hsu, Yung; Hsu, Chin-Wei; Yang, Ling-Gang; Chow, Chi-Wai; Yeh, Chien-Hung; Lai, Yin-Chieh; Tsang, Hon-Ki

    2016-02-01

    In this work, we propose and demonstrate a stable single-longitudinal-mode (SLM) fiber laser with narrow line-width by using an integrated silicon-on-insulator micro-ring resonator (SOI MRR) and two subsidiary fiber rings for the first time, to the best of our knowledge. The laser is tunable over the wavelength range from 1546 to 1570 nm, with only step tuning of 2 nm steps. A maximum 49 dB side mode suppression ratio (SMSR) can be achieved. The compact SOI MRR provides a large free-spectral-range (FSR), while the subsidiary rings provide Vernier effect producing a single lasing mode. The FSR of the SOI MRR can be very large and controllable (since it is easy to fabricate small SOI MRR when compared with making small fiber-rings) using the complementary-metal-oxide-semiconductor (CMOS) compactable SOI fabrication processes. In our proposed laser, the measured single sideband (SSB) spectrum shows that the densely spaced longitudinal modes can be significantly suppressed to achieve SLM. The laser linewidth is only 3.5 kHz measured by using the self-heterodyne method. 30 min stability evaluation in terms of lasing wavelength and optical power is performed; showing the optical wavelength and power are both very stable, with fluctuations of only 0.02 nm and 0.8 dB, respectively.

  8. Compact and broadband circularly polarized ring antenna with wide beam-width for multiple global navigation satellite systems

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Lin; Hu, Bin-Jie; Zhang, Xiu-Yin

    2012-02-01

    A compact and broadband circularly polarized (CP) annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems (GNSS) in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width (HPBW) is 113° in both the x—z and y—z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.

  9. Tree-ring-width-based PDSI reconstruction for central Inner Mongolia, China over the past 333 years

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Zhang, Xinjia; Song, Huiming; Cai, Qiufang; Li, Qiang; Zhao, Boyang; Liu, Han; Mei, Ruochen

    2016-04-01

    A tree-ring-width chronology was developed from Pinus tabulaeformis aged up to 333 years from central Inner Mongolia, China. The chronology was significantly correlated with the local Palmer Drought Severity Index (PDSI). We therefore reconstructed the first PDSI reconstruction from March to June based on the local tree ring data from 1680 to 2012 AD. The reconstruction explained 40.7 % of the variance (39.7 % after adjusted the degrees of freedom) of the actual PDSI during the calibration period (1951-2012 AD). The reconstructed PDSI series captured the severe drought event of the late 1920s, which occurred extensively in northern China. Running variance analyses indicated that the variability of drought increased sharply after 1960, indicating more drought years, which may imply anthropogenic related global warming effects in the region. In the entire reconstruction, there were five dry periods: 1730-1814 AD, 1849-1869 AD, 1886-1942 AD (including severe drought in late 1920s), 1963-1978 AD and 2004-2007 AD; and five wet periods: 1685-1729 AD, 1815-1848 AD, 1870-1885 AD, 1943-1962 AD and 1979-2003 AD. Conditions turned dry after 2003 AD, and the PDSI from March to June (PDSI36) captured many interannual extreme drought events since then, such as 2005-2008 AD. The reconstruction is comparable to other tree-ring-width-based PDSI series from the neighboring regions, indicating that our reconstruction has good regional representativeness. Significant relationships were found between our PDSI reconstruction and the solar radiation cycle and the sun spot cycle, North Atlantic Oscillation, the El Niño-Southern Oscillation, as well as the Pacific Decadal Oscillation. Power spectral analyses detected 147.0-, 128.2-, 46.5-, 6.5-, 6.3-, 2.6-, 2.2- and 2.0-year quasi-cycles in the reconstructed series.

  10. Dependence of alloying and island composition on terrace width: Growth of Cu on Ag(100)

    NASA Astrophysics Data System (ADS)

    Beichert, Agnes; Zaum, Christopher; Morgenstern, Karina

    2015-07-01

    The growth of Cu on Ag(100) is investigated by low-temperature scanning tunneling microscopy. Exchange diffusion of Cu deposited onto Ag(100) leads to small pure Cu islands and larger islands consisting of a CuAg alloy in room temperature growth. The ratio of the different types of islands depends on terrace widths up to 100 nm. This surprisingly long-range dependence is correlated to the density of the surface alloy. We thus reveal that the exchange diffusion barrier is influenced by terrace widths far beyond quantum size confinement.

  11. Parameterization of tree-ring growth in Siberia

    NASA Astrophysics Data System (ADS)

    Tychkov, Ivan; Popkova, Margarita; Shishov, Vladimir; Vaganov, Eugene

    2016-04-01

    No doubt, climate-tree growth relationship is an one of the useful and interesting subject of studying in dendrochronology. It provides an information of tree growth dependency on climatic environment, but also, gives information about growth conditions and whole tree-ring growth process for long-term periods. New parameterization approach of the Vaganov-Shashkin process-based model (VS-model) is developed to described critical process linking climate variables with tree-ring formation. The approach (co-called VS-Oscilloscope) is presented as a computer software with graphical interface. As most process-based tree-ring models, VS-model's initial purpose is to describe variability of tree-ring radial growth due to variability of climatic factors, but also to determinate principal factors limiting tree-ring growth. The principal factors affecting on the growth rate of cambial cells in the VS-model are temperature, day light and soil moisture. Detailed testing of VS-Oscilloscope was done for semi-arid area of southern Siberia (Khakassian region). Significant correlations between initial tree-ring chronologies and simulated tree-ring growth curves were obtained. Direct natural observations confirm obtained simulation results including unique growth characteristic for semi-arid habitats. New results concerning formation of wide and narrow rings under different climate conditions are considered. By itself the new parameterization approach (VS-oscilloscope) is an useful instrument for better understanding of various processes in tree-ring formation. The work was supported by the Russian Science Foundation (RSF # 14-14-00219).

  12. Enhancement of metastable zone width for solution growth of potassium acid phthalate

    NASA Astrophysics Data System (ADS)

    Srinivasan, K.; Meera, K.; Ramasamy, P.

    1999-09-01

    A new method has been developed in which the addition of a small amount of ethylenediamine tetra acetic acid (EDTA), a well-known chelating agent, enhances the metastable zone width significantly. Also, it has been found that this addition reduces the rate of nucleation and increases the growth rate of the crystal. This method has been employed for solution growth of potassium hydrogen phthalate (KC 8H 5O 4), which is also known as potassium acid phthalate (KAP).

  13. Relating tree growth to rainfall in Bolivian rain forests: a test for six species using tree ring analysis.

    PubMed

    Brienen, Roel J W; Zuidema, Pieter A

    2005-11-01

    Many tropical regions show one distinct dry season. Often, this seasonality induces cambial dormancy of trees, particularly if these belong to deciduous species. This will often lead to the formation of annual rings. The aim of this study was to determine whether tree species in the Bolivian Amazon region form annual rings and to study the influence of the total amount and seasonal distribution of rainfall on diameter growth. Ring widths were measured on stem discs of a total of 154 trees belonging to six rain forest species. By correlating ring width and monthly rainfall data we proved the annual character of the tree rings for four of our study species. For two other species the annual character was proved by counting rings on trees of known age and by radiocarbon dating. The results of the climate-growth analysis show a positive relationship between tree growth and rainfall in certain periods of the year, indicating that rainfall plays a major role in tree growth. Three species showed a strong relationship with rainfall at the beginning of the rainy season, while one species is most sensitive to the rainfall at the end of the previous growing season. These results clearly demonstrate that tree ring analysis can be successfully applied in the tropics and that it is a promising method for various research disciplines. PMID:16012820

  14. Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

    SciTech Connect

    Whitesides, R.; Domin, D.; Salomon-Ferrer, R.; Lester Jr., W.A.; Frenklach, M.

    2007-12-01

    Reaction pathways are presented for hydrogen-mediated isomerization of a five and six member carbon ring complex on the zigzag edge of a graphene layer. A new reaction sequence that reverses orientation of the ring complex, or 'flips' it, was identified. Competition between the flip reaction and 'ring separation' was examined. Ring separation is the reverse of the five and six member ring complex formation reaction, previously reported as 'ring collision'. The elementary steps of the pathways were analyzed using density-functional theory (DFT). Rate coefficients were obtained by solution of the energy master equation and classical transition state theory utilizing the DFT energies, frequencies, and geometries. The results indicate that the flip reaction pathway dominates the separation reaction and should be competitive with other pathways important to the graphene zigzag edge growth in high temperature environments.

  15. Detecting long-term growth trends using tree rings: a critical evaluation of methods.

    PubMed

    Peters, Richard L; Groenendijk, Peter; Vlam, Mart; Zuidema, Pieter A

    2015-05-01

    Tree-ring analysis is often used to assess long-term trends in tree growth. A variety of growth-trend detection methods (GDMs) exist to disentangle age/size trends in growth from long-term growth changes. However, these detrending methods strongly differ in approach, with possible implications for their output. Here, we critically evaluate the consistency, sensitivity, reliability and accuracy of four most widely used GDMs: conservative detrending (CD) applies mathematical functions to correct for decreasing ring widths with age; basal area correction (BAC) transforms diameter into basal area growth; regional curve standardization (RCS) detrends individual tree-ring series using average age/size trends; and size class isolation (SCI) calculates growth trends within separate size classes. First, we evaluated whether these GDMs produce consistent results applied to an empirical tree-ring data set of Melia azedarach, a tropical tree species from Thailand. Three GDMs yielded similar results - a growth decline over time - but the widely used CD method did not detect any change. Second, we assessed the sensitivity (probability of correct growth-trend detection), reliability (100% minus probability of detecting false trends) and accuracy (whether the strength of imposed trends is correctly detected) of these GDMs, by applying them to simulated growth trajectories with different imposed trends: no trend, strong trends (-6% and +6% change per decade) and weak trends (-2%, +2%). All methods except CD, showed high sensitivity, reliability and accuracy to detect strong imposed trends. However, these were considerably lower in the weak or no-trend scenarios. BAC showed good sensitivity and accuracy, but low reliability, indicating uncertainty of trend detection using this method. Our study reveals that the choice of GDM influences results of growth-trend studies. We recommend applying multiple methods when analysing trends and encourage performing sensitivity and reliability

  16. Sensitivity of ring growth and carbon allocation to climatic variation vary within ponderosa pine trees.

    PubMed

    Kerhoulas, Lucy P; Kane, Jeffrey M

    2012-01-01

    Most dendrochronological studies focus on cores sampled from standard positions (main stem, breast height), yet vertical gradients in hydraulic constraints and priorities for carbon allocation may contribute to different growth sensitivities with position. Using cores taken from five positions (coarse roots, breast height, base of live crown, mid-crown branch and treetop), we investigated how radial growth sensitivity to climate over the period of 1895-2008 varies by position within 36 large ponderosa pines (Pinus ponderosa Dougl.) in northern Arizona. The climate parameters investigated were Palmer Drought Severity Index, water year and monsoon precipitation, maximum annual temperature, minimum annual temperature and average annual temperature. For each study tree, we generated Pearson correlation coefficients between ring width indices from each position and six climate parameters. We also investigated whether the number of missing rings differed among positions and bole heights. We found that tree density did not significantly influence climatic sensitivity to any of the climate parameters investigated at any of the sample positions. Results from three types of analyses suggest that climatic sensitivity of tree growth varied with position height: (i) correlations of radial growth and climate variables consistently increased with height; (ii) model strength based on Akaike's information criterion increased with height, where treetop growth consistently had the highest sensitivity and coarse roots the lowest sensitivity to each climatic parameter; and (iii) the correlation between bole ring width indices decreased with distance between positions. We speculate that increased sensitivity to climate at higher positions is related to hydraulic limitation because higher positions experience greater xylem tensions due to gravitational effects that render these positions more sensitive to climatic stresses. The low sensitivity of root growth to all climatic variables

  17. A Standardized Precipitation Evapotranspiration Index Reconstruction in the Taihe Mountains Using Tree-Ring Widths for the Last 283 Years.

    PubMed

    Ma, Yongyong; Liu, Yu; Song, Huiming; Sun, Junyan; Lei, Ying; Wang, Yanchao

    2015-01-01

    Tree-ring samples from Chinese Pine (Pinus tabulaeformis Carr.) that were collected in the Taihe Mountains on the western Loess Plateau, China, were used to analyze the effects of climate and drought on radial growth and to reconstruct the mean April-June Standardized Precipitation Evapotranspiration Index (SPEI) during the period 1730-2012 AD. Precipitation positively affected tree growth primarily during wet seasons, while temperature negatively affected tree growth during dry seasons. Tree growth responded positively to SPEI at long time scales most likely because the trees were able to withstand water deficits but lacked a rapid response to drought. The 10-month scale SPEI was chosen for further drought reconstruction. A calibration model for the period 1951-2011 explained 51% of the variance in the modeled SPEI data. Our SPEI reconstruction revealed long-term patterns of drought variability and captured some significant drought events, including the severe drought of 1928-1930 and the clear drying trend since the 1950s which were widespread across northern China. The reconstruction was also consistent with two other reconstructions on the western Loess Plateau at both interannual and decadal scales. The reconstructed SPEI series showed synchronous variations with the drought/wetness indices and spatial correlation analyses indicated that this reconstruction could be representative of large-scale SPEI variability in northern China. Period analysis discovered 128-year, 25-year, 2.62-year, 2.36-year, and 2.04-year cycles in this reconstruction. The time-dependency of the growth response to drought should be considered in further studies of the community dynamics. The SPEI reconstruction improves the sparse network of long-term climate records for an enhanced understanding of climatic variability on the western Loess Plateau, China. PMID:26207621

  18. A Standardized Precipitation Evapotranspiration Index Reconstruction in the Taihe Mountains Using Tree-Ring Widths for the Last 283 Years

    PubMed Central

    Ma, Yongyong; Liu, Yu; Song, Huiming; Sun, Junyan; Lei, Ying; Wang, Yanchao

    2015-01-01

    Tree-ring samples from Chinese Pine (Pinus tabulaeformis Carr.) that were collected in the Taihe Mountains on the western Loess Plateau, China, were used to analyze the effects of climate and drought on radial growth and to reconstruct the mean April-June Standardized Precipitation Evapotranspiration Index (SPEI) during the period 1730–2012 AD. Precipitation positively affected tree growth primarily during wet seasons, while temperature negatively affected tree growth during dry seasons. Tree growth responded positively to SPEI at long time scales most likely because the trees were able to withstand water deficits but lacked a rapid response to drought. The 10-month scale SPEI was chosen for further drought reconstruction. A calibration model for the period 1951–2011 explained 51% of the variance in the modeled SPEI data. Our SPEI reconstruction revealed long-term patterns of drought variability and captured some significant drought events, including the severe drought of 1928–1930 and the clear drying trend since the 1950s which were widespread across northern China. The reconstruction was also consistent with two other reconstructions on the western Loess Plateau at both interannual and decadal scales. The reconstructed SPEI series showed synchronous variations with the drought/wetness indices and spatial correlation analyses indicated that this reconstruction could be representative of large-scale SPEI variability in northern China. Period analysis discovered 128-year, 25-year, 2.62-year, 2.36-year, and 2.04-year cycles in this reconstruction. The time-dependency of the growth response to drought should be considered in further studies of the community dynamics. The SPEI reconstruction improves the sparse network of long-term climate records for an enhanced understanding of climatic variability on the western Loess Plateau, China. PMID:26207621

  19. A 323-year long reconstruction of drought for SW Romania based on black pine ( Pinus Nigra) tree-ring widths

    NASA Astrophysics Data System (ADS)

    Levanič, Tom; Popa, Ionel; Poljanšek, Simon; Nechita, Constantin

    2013-09-01

    Increase in temperature and decrease in precipitation pose a major future challenge for sustainable ecosystem management in Romania. To understand ecosystem response and the wider social consequences of environmental change, we constructed a 396-year long (1615-2010) drought sensitive tree-ring width chronology (TRW) of Pinus nigra var. banatica (Georg. et Ion.) growing on steep slopes and shallow organic soil. We established a statistical relationship between TRW and two meteorological parameters—monthly sum of precipitation (PP) and standardised precipitation index (SPI). PP and SPI correlate significantly with TRW ( r = 0.54 and 0.58) and are stable in time. Rigorous statistical tests, which measure the accuracy and prediction ability of the model, were all significant. SPI was eventually reconstructed back to 1688, with extreme dry and wet years identified using the percentile method. By means of reconstruction, we identified two so far unknown extremely dry years in Romania—1725 and 1782. Those 2 years are almost as dry as 1946, which was known as the "year of great famine." Since no historical documents for these 2 years were available in local archives, we compared the results with those from neighbouring countries and discovered that both years were extremely dry in the wider region (Slovakia, Hungary, Anatolia, Syria, and Turkey). While the 1800-1900 period was relatively mild, with only two moderately extreme years as far as weather is concerned, the 1900-2009 period was highly salient owing to the very high number of wet and dry extremes—five extremely wet and three extremely dry events (one of them in 1946) were identified.

  20. [Tree-ring growth responses of Mongolian oak (Quercus mongolica) to climate change in southern northeast: a case study in Qianshan Mountains].

    PubMed

    Teng, Li; Xing-Yuan, He; Zhen-Ju, Chen

    2014-07-01

    Mongolian oak is one of the most important broad-leaved tree species in forests, Northeast China. Based on the methodology of dendrochronology, the variations of tree ring radial growth of Mongolian oak in Qianshan Mountains, south of Northeast China, were analyzed. Combined with the temperature and precipitation data from meteorological stations since 1951, the relationships between standardized tree ring width chronology and main climatic factors were analyzed. In this region, the precipitation between April and July of the current year had an significant relationship with the tree ring width of Mongolian oak, and was the main factor limiting the radial growth. The extreme maximum temperature of May was also a key factor influencing the tree ring width, which had a significant on the tree ring width of Mongolian oak. The precipitation in April had a significant and stable relationship with the growth of Mongolian oak since the 1950s. The 'divergence problem' was found in the study area, which the sensitivity of tree growth to summer temperature reduced since the 1980s. The tree growth response to temperature showed a seasonal change from summer to spring. PMID:25345030

  1. Downsag calderas, ring faults, caldera sizes, and incremental caldera growth

    NASA Astrophysics Data System (ADS)

    Walker, G. P. L.

    1984-09-01

    According to present concepts, a caldera is a more or less circular volcanic depression larger than a crater which is caused by subsidence. It is commonly considered that the subsided mass consists of a block or blocks encircled by a ring fracture. Caldera collapse is generally correlated with a major explosive eruption. The present investigation is concerned with six features which do not conform well with the favored caldera model. Attention is given to downsagged calderas, the distribution of postcaldera vents in calderas, vent rings, the size of calderas and cauldrons, incremental caldera growth, and caldera-forming events. It is found that no single structural or genetic model applies to all calderas. Thus, the fact of subsidence may be the only common feature. It is pointed out that most known ring dikes occur in Precambrian crust. This may mean that the subsiding piston mechanism operates best where the crust is sufficiently rigid and strong.

  2. Radial growth of an extended spoke in Saturn's B ring

    NASA Technical Reports Server (NTRS)

    Eplee, R. E., Jr.; Smith, B. A.

    1985-01-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring 'movie'. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density.

  3. Radial growth of an extended spoke in Saturn's B ring

    SciTech Connect

    Eplee, R.E.,JR.; Smith, B.A.

    1985-08-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring movie. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density. 13 references.

  4. Do tree ring chronologies have missing rings that distort volcanic cooling signal?: Tree ring records not distorted by missing rings

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-09-01

    Tree ring records are often used as a proxy for past climate. Trees form a new growth ring each year, and ring widths are related to temperature and other conditions at cold sites. Some recent studies have noted that tree ring width chronologies and resulting climate reconstructions do not appear to show the widespread cooling in the past millennium that would be expected following large volcanic eruptions. One hypothesis suggests that regional cooling after a volcanic eruption could be so severe that many trees do not form a ring at all, which leads researchers to misdate the tree ring chronology.

  5. Research of narrow line-width Er3+-doped fiber ring laser with FBG F-P etalon and FBG Sagnac loop

    NASA Astrophysics Data System (ADS)

    Ou, Zhonghua; Dai, Zhiyong; Wu, Bo; Zhang, Lixun; Peng, Zengshou; Liu, Yongzhi

    2008-12-01

    A novel method of narrow line-width Er3+-doped fiber ring laser based on FBG F-P etalon and FBG Sagnac loop is presented in this paper. The all-fiber single frequency and narrow line-width Er3+-doped fiber ring laser has been designed in which two 976 nm laser diodes are used as the pump sources, the high concentration Er3+-doped fiber as the gain medium, the fiber Faraday rotator is adopted to eliminate the spatial hole burning effect, the FBG F-P etalon and FBG Sagnac loop filter can discriminate and select laser longitudinal modes efficiently. The experiment system using 3m long Er3+-doped fibers is presented, when the maximum pump power of two 976nm laser diodes is 146mW, the fiber laser exhibits 16mW threshold and stable single frequency 1550nm laser with the output powers of 45mW is acquired, and the slope efficiency is about 34.6%. The 3dB line-width is less than 9.3 kHz, measured by the delayed selfheterodyne method with 15km single-mode fiber, and no mode hopping is observed. The fiber laser has the advantages of simple structure, high efficiency and high reliability and it has great potential applications in the fields of optical fiber sensing system.

  6. Variations in Environmental Signals in Tree-Ring Indices in Trees with Different Growth Potential.

    PubMed

    Hafner, Polona; Gričar, Jožica; Skudnik, Mitja; Levanič, Tom

    2015-01-01

    We analysed two groups of Quercus robur trees, growing at nearby plots with different micro-location condition (W-wet and D-dry) in the floodplain Krakovo forest, Slovenia. In the study we compared the growth response of two different tree groups to environmental variables, the potential signal stored in earlywood (EW) structure and the potential difference of the information stored in carbon isotope discrimination of EW and latewood (LW). For that purpose EW and LW widths and carbon isotope discrimination for the period 1970-2008 AD were measured. EW and LW widths were measured on stained microscopic slides and chronologies were standardised using the ARSTAN program. α-cellulose was extracted from pooled EW and LW samples and homogenized samples were further analysed using an elemental analyser and IRMS. We discovered that W oaks grew significantly better over the whole analysed period. The difference between D and W oaks was significant in all analysed variables with the exception of stable carbon isotope discrimination in latewood. In W oaks, latewood widths correlated with summer (June to August) climatic variables, while carbon isotope discrimination was more connected to River Krka flow during the summer. EW discrimination correlated with summer and autumn River Krka flow of the previous year, while latewood discrimination correlated with flow during the current year. In the case of D oaks, the environmental signal appears to be vague, probably due to less favourable growth conditions resulting in markedly reduced increments. Our study revealed important differences in responses to environmental factors between the two oak groups of different physiological conditions that are preconditioned by environmental stress. Environmental information stored in tree-ring features may vary, even within the same forest stand, and largely depends on the micro-environment. Our analysis confirmed our assumptions that separate EW and LW analysis of widths and carbon isotope

  7. Variations in Environmental Signals in Tree-Ring Indices in Trees with Different Growth Potential

    PubMed Central

    Hafner, Polona; Gričar, Jožica; Skudnik, Mitja; Levanič, Tom

    2015-01-01

    We analysed two groups of Quercus robur trees, growing at nearby plots with different micro-location condition (W-wet and D-dry) in the floodplain Krakovo forest, Slovenia. In the study we compared the growth response of two different tree groups to environmental variables, the potential signal stored in earlywood (EW) structure and the potential difference of the information stored in carbon isotope discrimination of EW and latewood (LW). For that purpose EW and LW widths and carbon isotope discrimination for the period 1970–2008 AD were measured. EW and LW widths were measured on stained microscopic slides and chronologies were standardised using the ARSTAN program. α-cellulose was extracted from pooled EW and LW samples and homogenized samples were further analysed using an elemental analyser and IRMS. We discovered that W oaks grew significantly better over the whole analysed period. The difference between D and W oaks was significant in all analysed variables with the exception of stable carbon isotope discrimination in latewood. In W oaks, latewood widths correlated with summer (June to August) climatic variables, while carbon isotope discrimination was more connected to River Krka flow during the summer. EW discrimination correlated with summer and autumn River Krka flow of the previous year, while latewood discrimination correlated with flow during the current year. In the case of D oaks, the environmental signal appears to be vague, probably due to less favourable growth conditions resulting in markedly reduced increments. Our study revealed important differences in responses to environmental factors between the two oak groups of different physiological conditions that are preconditioned by environmental stress. Environmental information stored in tree-ring features may vary, even within the same forest stand, and largely depends on the micro-environment. Our analysis confirmed our assumptions that separate EW and LW analysis of widths and carbon

  8. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study.

    PubMed

    Leland, Caroline; Hom, John; Skowronski, Nicholas; Ledig, F Thomas; Krusic, Paul J; Cook, Edward R; Martin-Benito, Dario; Martin-Fernandez, Javier; Pederson, Neil

    2016-01-01

    Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.) trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years-1992, 1999, and 2006-had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation) had a significantly smaller percentage of missing rings from 1980-2009 (mean: 5.0%), relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively). Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle. PMID:27182599

  9. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study

    PubMed Central

    Leland, Caroline; Hom, John; Skowronski, Nicholas; Krusic, Paul J.; Cook, Edward R.; Martin-Benito, Dario; Martin-Fernandez, Javier; Pederson, Neil

    2016-01-01

    Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.) trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years—1992, 1999, and 2006—had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation) had a significantly smaller percentage of missing rings from 1980–2009 (mean: 5.0%), relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively). Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle. PMID:27182599

  10. Telemetry carrier ring and support

    NASA Technical Reports Server (NTRS)

    Wakeman, Thomas G. (Inventor)

    1992-01-01

    A telemetry carrier ring for use in a gas turbine engine includes an annular support ring connected to the engine and an annular carrier ring coupled to the support ring, each ring exhibiting different growth characteristics in response to thermal and mechanical loading. The carrier ring is coupled to the support ring by a plurality of circumferentially spaced web members which are relatively thin in an engine radial direction to provide a predetermined degree of radial flexibility. the web members have a circumferential width and straight axial line of action selected to transfer torque and thrust between the support ring and the carrier ring without substantial deflection. The use of the web members with radial flexibility provides compensation between the support ring and the carrier ring since the carrier ring grows at a different rate than the supporting ring.

  11. Tree-ring growth and wood chemistry response to manipulated precipitation variation for two temperate Quercus species

    SciTech Connect

    Wagner, Rebekah J.; Kaye, Margot W.; Abrams, Marc D.; Hanson, Paul J; Martin, Madhavi Z

    2012-01-01

    We examined the relationship among ambient and manipulated precipitation, wood chemistry, and their relationship with radial growth for two oak species in eastern Tennessee. The study took place on the Walker Branch Throughfall Displacement Experiment (TDE) site, located at the Oak Ridge National Laboratory in Oak Ridge, TN. Two dominant species, white oak (Quercus alba) and chestnut oak (Quercus prinus), were selected for study from a 13-year experiment of whole-stand precipitation manipulation (wet, ambient and dry). The relationships between tree-ring width and climate were compared for both species to determine the impact of precipitation manipulations on ring width index. This study used experimental spectroscopy techniques to measure the sensitivity of tree-ring responses to directional changes in precipitation over 13 years, and the results suggest that oaks at this study site are resilient to imposed changes, but sensitive to inter-annual variations in climate. Laser-induced breakdown spectroscopy (LIBS) allowed us to measure nutrient intensities (similar to element concentrations) at 0.5-1.0 mm spacing along the radial growth axis of trees growing in the wet, ambient, and dry treatment sites. A difference in stemwood nutrient levels was observed between the two oak species and among the three treatments. Significant variation in element intensity was observed across treatments for some elements (Ca, K, Mg, Na, N and P) suggesting the potential for long-term impacts on growth under a changing climate regimes for southeastern oaks.

  12. Understanding tree growth in response to moisture variability: Linking 32 years of satellite based soil moisture observations with tree rings

    NASA Astrophysics Data System (ADS)

    Albrecht, Franziska; Dorigo, Wouter; Gruber, Alexander; Wagner, Wolfgang; Kainz, Wolfgang

    2014-05-01

    Climate change induced drought variability impacts global forest ecosystems and forest carbon cycle dynamics. Physiological drought stress might even become an issue in regions generally not considered water-limited. The water balance at the soil surface is essential for forest growth. Soil moisture is a key driver linking precipitation and tree development. Tree ring based analyses are a potential approach to study the driving role of hydrological parameters for tree growth. However, at present two major research gaps are apparent: i) soil moisture records are hardly considered and ii) only a few studies are linking tree ring chronologies and satellite observations. Here we used tree ring chronologies obtained from the International Tree ring Data Bank (ITRDB) and remotely sensed soil moisture observations (ECV_SM) to analyze the moisture-tree growth relationship. The ECV_SM dataset, which is being distributed through ESA's Climate Change Initiative for soil moisture covers the period 1979 to 2010 at a spatial resolution of 0.25°. First analyses were performed for Mongolia, a country characterized by a continental arid climate. We extracted 13 tree ring chronologies suitable for our analysis from the ITRDB. Using monthly satellite based soil moisture observations we confirmed previous studies on the seasonality of soil moisture in Mongolia. Further, we investigated the relationship between tree growth (as reflected by tree ring width index) and remotely sensed soil moisture records by applying correlation analysis. In terms of correlation coefficient a strong response of tree growth to soil moisture conditions of current April to August was observed, confirming a strong linkage between tree growth and soil water storage. The highest correlation was found for current April (R=0.44), indicating that sufficient water supply is vital for trees at the beginning of the growing season. To verify these results, we related the chronologies to reanalysis precipitation and

  13. Early summer temperature reconstruction in the eastern Tibetan plateau since ad 1440 using tree-ring width of Sabina tibetica

    NASA Astrophysics Data System (ADS)

    Zhu, Hai-Feng; Shao, Xue-Mei; Yin, Zhi-Yong; Huang, Lei

    2011-11-01

    Long climate records are scarce on the Tibetan Plateau for understanding the climate variability on long-term context. Here we presented an early summer (May-June) temperature reconstruction since ad 1440 for Qamdo area using tree rings of Sabina tibetica. The reconstruction accounted for 64% of the variance in the instrumental record. It showed warm periods during 1501-1514, 1528-1538, 1598-1609, 1624-1636, 1650-1668, 1695-1705, 1752-1762, 1794-1804, 1878-1890, 1909-1921, 1938-1949, and 1979-1991. Cool early summer occurred during 1440-1454, 1482-1500, 1515-1527, 1576-1597, 1610-1621, 1669-1679, 1706-1716, 1782-1793, 1863-1873, 1894-1908, and 1922-1937. Comparison with other proxy or meteorological records suggested that there is obvious spatial variability in the May-June temperature variations along the eastern margin of the Tibetan Plateau.

  14. Initial reconstruction of the climate in the last millennium in the central Kola Peninsula (north-western Russia) based on tree-ring widths and stable isotope data of pine (PINUS SYLVESTRIS L.)

    NASA Astrophysics Data System (ADS)

    Boettger, T.; Kononov, Yu.; Friedrich, M.; Kremenetski, C.

    2003-04-01

    More than 300 samples of living tree cores and subfossil slices of Pinus sylvestris L. have been taken in the course of joint field investigations in the Khibiny low mountains in the central part of the Kola Peninsula (approx. 67-68^oN, 33-34^oE). The samples collected enabled a continuous chronological series 1139 years long to be constructed from AD 2000 to 862. It is currently the longest chronological sequence in the region. Comparison between annual ring width and instrumental climatic records over the period 1923-2000 revealed close correlation between the index of annual wood growth and the summer air temperature. In addition, 10 samples of cores taken from living trees were studied by annual isotope analysis (^δ13C and δ18O) of the wood cellulose of their tree rings. Analysis of annual isotope variations in tree ring series are most promising for climatic reconstructions. A significant relationship was established between the proportion of ^δ13C isotope and the mean summer temperature. This formed the basis for reconstructions of the main warming and cooling periods over the period under consideration. Altogether there were 12 significant cooling periods, each about 10-20 years long. As for warmings, they were fewer in number (7) but lasted longer (about 40-90 years). Very strong coolings occurred twice. The first one was from the beginning of the interval studied until AD 884. In all probability, this actually represented the termination of the previous, even colder period, when the weather prevented any tree growth. The second cooling was in 1641-1654, and there is good reason for believing that this was a local manifestation of the Little Ice Age. The mean summer temperature at that time was almost 5^o below that nowadays.

  15. A method to separate temperature and precipitation signals encoded in tree-ring widths for the western Tien Shan Mountains, northwest China

    NASA Astrophysics Data System (ADS)

    Liu, Wenhuo; Gou, Xiaohua; Li, Jinbao; Huo, Yuxia; Fang, Keyan

    2015-10-01

    Separating temperature and precipitation signals encoded in tree rings is a complicated issue. Here, we present a separation method by combining two tree-ring width chronologies of Schrenk's spruce (Picea schrenkiana) from the upper and lower timberlines in the western Tien Shan Mountains, northwest China. Correlation analyses show that both chronologies correlate positively with precipitation. However, temperature correlates positively with the chronology from the upper timberline, while negatively with the chronology from the lower timberline. This suggests that the two chronologies contain similar precipitation information but opposite temperature signals. In light of this, we calculated the average and difference of the two chronologies, and found that each of them has a much stronger correlation with precipitation or temperature alone. Finally, we reconstructed local precipitation and temperature variations over the past 201 years by using the average and difference of the two chronologies. The two reconstructions do not have a significant correlation, but they have significant positive and negative relationships on the high- and low-frequency band, respectively.

  16. Integrating inter- and intra-annual tree-ring width, carbon isotopes and anatomy: responses to climate variability in a temperate oak forest

    NASA Astrophysics Data System (ADS)

    Granda, Elena; Bazot, Stéphane; Fresneau, Chantal; Boura, Anaïs; Faccioni, Georgia; Damesin, Claire

    2015-04-01

    While many forests are experiencing strong tree declines due to climate change in temperate ecosystems, others nearby to those declining show no apparent signs of decline. This could be due to particular microsite conditions or, for instance, to a higher plasticity of given traits that allow a better performance under stressful conditions. We studied oak functional mechanisms (Quercus petraea) leading to the apparently healthy status of the forest and their relation to the observed climatic variability. This study was conducted in the Barbeau Forest (northern France), where cores from mature trees were collected. Three types of functional traits (secondary growth, physiological variables - δ13C and derived Δ13C and iWUE- and several anatomical ones -e.g. vessel area, density-) were recorded for each ring for the 1991-2011 period, distinguishing EW from LW in all measured traits. Among the three types of functional traits, those related to growth experienced the highest variability both between years and between individuals, followed by anatomical and physiological ones. Secondary growth maintained a constant trend during the study period. Instead, ring, EW and LW δ13C slightly declined from 1991 to 2011. Additional intra-ring δ13C analyses allowed for a more detailed understanding of the seasonal dynamics within each year. In particular, the year 2007 (an especially favorable climatic year during the growing season) showed the lowest δ13C values during the EW-LW transition for the whole study period. Inter-annual anatomical traits varied in their responses, but in general, no temporal trends were found. The results from structural equation modeling (SEM) showed direct relationships of seasonal climate and growth, as well as indirect relationships mediated by anatomical and physiological traits. We further discuss the implications of these results on future forest responses to ongoing climate changes.

  17. Graphene Layer Growth: Collision of Migrating Five-MemberRings

    SciTech Connect

    Whitesides, Russell; Kollias, Alexander C.; Domin, Dominik; Lester Jr., William A.; Frenklach, Michael

    2005-12-02

    A reaction pathway is explored in which two cyclopenta groups combine on the zigzag edge of a graphene layer. The process is initiated by H addition to a five-membered ring, followed by opening of that ring and the formation of a six-membered ring adjacent to another five-membered ring. The elementary steps of the migration pathway are analyzed using density functional theory to examine the region of the potential energy surface associated with the pathway. The calculations are performed on a substrate modeled by the zigzag edge of tetracene. Based on the obtained energetics, the dynamics of the system are analyzed by solving the energy transfer master equations. The results indicate energetic and reaction-rate similarity between the cyclopenta combination and migration reactions. Also examined in the present study are desorption rates of migrating cyclopenta rings which are found to be comparable to cyclopenta ring migration.

  18. Ethylene evolution, radial growth and carbohydrate concentrations in Abies balsamea shoots ringed with Ethrel.

    PubMed

    Eklund, Leif; Little, C. H. Anthony

    1998-06-01

    The terminal (1-year-old) shoot of quiescent, 2-year-old Abies balsamea (L.) Mill. seedlings was either left untreated or ringed with 0, 1 or 10 mg Ethrel g(-1) lanolin. After 5 weeks of culture under environmental conditions favorable for growth, the shoots were harvested to measure ethylene evolution and carbohydrate concentrations by gas chromatography, and tracheid number and bark radial width by microscopy. In untreated shoots, the basal rate of ethylene evolution followed the order: cambial region > cortex + periderm = xylem + pith = needles. Wound-induced ethylene production was not detected until at least 4 h after excision, but was evident in all fractions 24 h after excision; the increase in wound-induced ethylene evolution followed the order: cambial region > cortex + periderm > xylem + pith > needles. Compared with untreated controls, the application of plain lanolin, which involved the removal of needles and periderm, increased bark radial width and wound-induced ethylene production by the cambial region and the cortex + periderm, but decreased cambial region concentrations of fructose, glucose and starch at the application point. At the application point, Ethrel concomitantly increased ethylene evolution from the cambial region and the cortex + periderm, tracheid number, bark radial width, and the cambial region concentrations of fructose, glucose, sucrose and starch. No effects of Ethrel treatment were detected above or below the application point, with the exception that the 10 mg g(-1) Ethrel treatment stimulated ethylene evolution and decreased starch concentration of the cambial region. The results indicate that: (1) the cambial region is the major source of endogenous ethylene in the 1-year-old shoot; (2) the magnitude of the difference in ethylene evolution between particular shoot fractions is different before and after the start of wound-induced ethylene production; (3) the Ethrel-induced increase in tracheid number and bark radial width at

  19. Ring chromosome 5 associated with severe growth retardation as the sole major physical abnormality

    SciTech Connect

    Migliori, M.V.; Pettinari, A.; Cherubini, V.; Bartolotta, E.; Pecora, R.

    1994-01-01

    The authors report on a case of ring chromosome 5 in a 36-month-old girl with severe growth retardation, clinodactyly, mild psychological abnormalities, and normal facial appearance. Endocrine tests showed partial growth hormone deficiency. Cytogenetic investigation failed to demonstrate any apparent microscopic deletion of either the short or long arm of chromosome 5 as a consequence of ring formation. In 12% of cells examined, the ring was either absent or present in multiple copies. Only 3 previous cases of ring chromosome 5 have been reported in association with short stature of prenatal onset and minor anomalies, without mental retardation. 12 refs., 3 figs.

  20. The Effects of Variations in Jet Width on the Growth of Baroclinic Waves: Implications for Midwinter Pacific Storm Track Variability.

    NASA Astrophysics Data System (ADS)

    Harnik, Nili; Chang, Edmund K. M.

    2004-01-01

    The effects of variations in jet width on the downstream growth of baroclinic waves are studied, using a simple quasigeostrophic model with a vertically varying basic state and variable channel width, as well as a simplified primitive equation model with a basic state that varies in latitude and height. This study is motivated by observations that in midwinter in the Pacific the storm track is weaker and the jet is narrower during years when the jet is strong.The linear models are able to reproduce the observed decrease of spatial growth rate with shear, if the narrowing of the jet is accounted for by assuming it decreases the meridional wavelength of the perturbations, which hampers their growth. A common suggestion has been that perturbations are weaker when the jet is strong because they move faster out of the unstable storm track region. The authors find that one needs to take into account that the jet narrows when it strengthens; otherwise, the increase of growth rate is strong enough to counteract the effect of increased advection speed.It is also found that, when the model basic state is Eady-like (small or zero meridional potential vorticity gradients in the troposphere), the short-wave cutoff for instability moves to large-scale waves as shear is increased, due to the accompanying increase in meridional wavenumber. This results in a transition from a regime where upper-level perturbations spin up a surface circulation very rapidly, and normal-mode growth ensues, to a regime where the initial perturbations take a very long time to excite growth. Since waves slow down when a surface perturbation develops, this can explain the observations that the storm track perturbations are more “upper level” during strong jet years and their group velocities increase faster than linearly with shear.

  1. Sensitivity of tree ring growth to local and large-scale climate variability in a region of Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Venegas-González, Alejandro; Chagas, Matheus Peres; Anholetto Júnior, Claudio Roberto; Alvares, Clayton Alcarde; Roig, Fidel Alejandro; Tomazello Filho, Mario

    2016-01-01

    We explored the relationship between tree growth in two tropical species and local and large-scale climate variability in Southeastern Brazil. Tree ring width chronologies of Tectona grandis (teak) and Pinus caribaea (Caribbean pine) trees were compared with local (Water Requirement Satisfaction Index—WRSI, Standardized Precipitation Index—SPI, and Palmer Drought Severity Index—PDSI) and large-scale climate indices that analyze the equatorial pacific sea surface temperature (Trans-Niño Index-TNI and Niño-3.4-N3.4) and atmospheric circulation variations in the Southern Hemisphere (Antarctic Oscillation-AAO). Teak trees showed positive correlation with three indices in the current summer and fall. A significant correlation between WRSI index and Caribbean pine was observed in the dry season preceding tree ring formation. The influence of large-scale climate patterns was observed only for TNI and AAO, where there was a radial growth reduction in months preceding the growing season with positive values of the TNI in teak trees and radial growth increase (decrease) during December (March) to February (May) of the previous (current) growing season with positive phase of the AAO in teak (Caribbean pine) trees. The development of a new dendroclimatological study in Southeastern Brazil sheds light to local and large-scale climate influence on tree growth in recent decades, contributing in future climate change studies.

  2. The influence of summertime fog and overcast clouds on the growth of a coastal Californian pine: a tree-ring study.

    PubMed

    Williams, A Park; Still, Christopher J; Fischer, Douglas T; Leavitt, Steven W

    2008-06-01

    The coast of California is home to numerous rare, endemic conifers and other plants that are limited in distribution by drought sensitivity and the summer-dry climate that prevails across most of the state. Ecologists have long assumed that some coastal plant populations survived the early Pleistocene transition to a warmer and drier environment because they benefit from frequent fog and stratus clouds that provide water and shade during the rainless summer. One such population is that of Torrey pine (Pinus torreyana ssp. Insularis) on Santa Rosa Island in Channel Islands National Park. Here we report that the tree-ring width record from this population indicates strong growth sensitivities to summer fog drip and cloud shading. We quantified the effects of summer cloud cover by comparing ring-width indices to coastal airport cloud-frequency records (1944-2004). For the first time observed, summertime cloud frequency correlated positively with ring-width indices, regardless of whether the effect of rainfall was first removed from the ring-width record. The effect of ground-level fog was strongest in July early mornings (03:00 PST, R(2) = 0.262, P < 0.0002). The effect of clouds high enough to provide shade but not fog water was also strongest in July, but climbed steadily throughout the day before becoming strongest in late afternoon (16:00-18:00 PST, R(2) = 0.148, P < 0.004). Correlations were substantially stronger in years with higher soil moisture, suggesting that growth response to summer clouds is strongly affected by pre-summer rainfall. A change in the height and/or timing of coastal cloud formation with climate change would likely affect this and other populations of California's coastal vegetation. PMID:18368424

  3. Growth cessation uncouples isotopic signals in leaves and tree rings of drought-exposed oak trees.

    PubMed

    Pflug, Ellen E; Siegwolf, R; Buchmann, N; Dobbertin, M; Kuster, T M; Günthardt-Goerg, M S; Arend, M

    2015-10-01

    An increase in temperature along with a decrease in summer precipitation in Central Europe will result in an increased frequency of drought events and gradually lead to a change in species composition in forest ecosystems. In the present study, young oaks (Quercus robur L. and Quercus petraea (Matt.) Liebl.) were transplanted into large mesocosms and exposed for 3 years to experimental warming and a drought treatment with yearly increasing intensities. Carbon and oxygen isotopic (δ(13)C and δ(18)O) patterns were analysed in leaf tissue and tree-ring cellulose and linked to leaf physiological measures and tree-ring growth. Warming had no effect on the isotopic patterns in leaves and tree rings, while drought increased δ(18)O and δ(13)C. Under severe drought, an unexpected isotopic pattern, with a decrease in δ(18)O, was observed in tree rings but not in leaves. This decrease in δ(18)O could not be explained by concurrent physiological analyses and is not supported by current physiological knowledge. Analysis of intra-annual tree-ring growth revealed a drought-induced growth cessation that interfered with the record of isotopic signals imprinted on recently formed leaf carbohydrates. This missing record indicates isotopic uncoupling of leaves and tree rings, which may have serious implications for the interpretation of tree-ring isotopes, particularly from trees that experienced growth-limiting stresses. PMID:26377873

  4. A Picea crassifolia Tree-Ring Width-Based Temperature Reconstruction for the Mt. Dongda Region, Northwest China, and Its Relationship to Large-Scale Climate Forcing.

    PubMed

    Liu, Yu; Sun, Changfeng; Li, Qiang; Cai, Qiufang

    2016-01-01

    The historical May-October mean temperature since 1831 was reconstructed based on tree-ring width of Qinghai spruce (Picea crassifolia Kom.) collected on Mt. Dongda, North of the Hexi Corridor in Northwest China. The regression model explained 46.6% of the variance of the instrumentally observed temperature. The cold periods in the reconstruction were 1831-1889, 1894-1901, 1908-1934 and 1950-1952, and the warm periods were 1890-1893, 1902-1907, 1935-1949 and 1953-2011. During the instrumental period (1951-2011), an obvious warming trend appeared in the last twenty years. The reconstruction displayed similar patterns to a temperature reconstruction from the east-central Tibetan Plateau at the inter-decadal timescale, indicating that the temperature reconstruction in this study was a reliable proxy for Northwest China. It was also found that the reconstruction series had good consistency with the Northern Hemisphere temperature at a decadal timescale. Multi-taper method spectral analysis detected some low- and high-frequency cycles (2.3-2.4-year, 2.8-year, 3.4-3.6-year, 5.0-year, 9.9-year and 27.0-year). Combining these cycles, the relationship of the low-frequency change with the Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO) and Southern Oscillation (SO) suggested that the reconstructed temperature variations may be related to large-scale atmospheric-oceanic variations. Major volcanic eruptions were partly reflected in the reconstructed temperatures after high-pass filtering; these events promoted anomalous cooling in this region. The results of this study not only provide new information for assessing the long-term temperature changes in the Hexi Corridor of Northwest China, but also further demonstrate the effects of large-scale atmospheric-oceanic circulation on climate change in Northwest China. PMID:27509206

  5. A Picea crassifolia Tree-Ring Width-Based Temperature Reconstruction for the Mt. Dongda Region, Northwest China, and Its Relationship to Large-Scale Climate Forcing

    PubMed Central

    Liu, Yu; Sun, Changfeng; Li, Qiang; Cai, Qiufang

    2016-01-01

    The historical May–October mean temperature since 1831 was reconstructed based on tree-ring width of Qinghai spruce (Picea crassifolia Kom.) collected on Mt. Dongda, North of the Hexi Corridor in Northwest China. The regression model explained 46.6% of the variance of the instrumentally observed temperature. The cold periods in the reconstruction were 1831–1889, 1894–1901, 1908–1934 and 1950–1952, and the warm periods were 1890–1893, 1902–1907, 1935–1949 and 1953–2011. During the instrumental period (1951–2011), an obvious warming trend appeared in the last twenty years. The reconstruction displayed similar patterns to a temperature reconstruction from the east-central Tibetan Plateau at the inter-decadal timescale, indicating that the temperature reconstruction in this study was a reliable proxy for Northwest China. It was also found that the reconstruction series had good consistency with the Northern Hemisphere temperature at a decadal timescale. Multi-taper method spectral analysis detected some low- and high-frequency cycles (2.3–2.4-year, 2.8-year, 3.4–3.6-year, 5.0-year, 9.9-year and 27.0-year). Combining these cycles, the relationship of the low-frequency change with the Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO) and Southern Oscillation (SO) suggested that the reconstructed temperature variations may be related to large-scale atmospheric-oceanic variations. Major volcanic eruptions were partly reflected in the reconstructed temperatures after high-pass filtering; these events promoted anomalous cooling in this region. The results of this study not only provide new information for assessing the long-term temperature changes in the Hexi Corridor of Northwest China, but also further demonstrate the effects of large-scale atmospheric-oceanic circulation on climate change in Northwest China. PMID:27509206

  6. The suitability of annual tree growth rings as environmental archives: Evidence from Sr, Nd, Pb and Ca isotopes in spruce growth rings from the Strengbach watershed

    NASA Astrophysics Data System (ADS)

    Stille, Peter; Schmitt, Anne-Désirée; Labolle, François; Pierret, Marie-Claire; Gangloff, Sophie; Cobert, Florian; Lucot, Eric; Guéguen, Florence; Brioschi, Laure; Steinmann, Marc; Chabaux, François

    2012-05-01

    The combination of the Sr, Nd and Pb isotope systems, recognized as tracers of sources, with the Ca isotope system, known to reveal biology-related fractionations, allowed us to test the reliability of spruce (Picea abies) growth rings as environmental archives through time (from 1916 to 1983) in a forest ecosystem affected by acid atmospheric deposition. Sr and Pb isotopes have already been applied in former tree-ring studies, whereas the suitability of Nd and Ca isotope systems is checked in the present article. Our Sr and Nd isotope data indicate an evolution in the cation origin with a geogenic origin for the oldest rings and an atmospheric origin for the youngest rings. Ca isotopes show, for their part, an isotopic homogeneity which could be linked to the very low weathering flux of Ca. Since this flux is weak the spruces' root systems have pumped the Ca mainly from the organic matter-rich top-soil over the past century. In contrast, the annual growth rings studied are not reliable and suitable archives of past Pb pollution.

  7. Rings

    SciTech Connect

    Davis, R.L.

    1989-01-01

    The essence of vortex physics is that at certain low-energy scales elementary excitations of a point particle theory can behave like strings rather than particles. Vortices are the resulting string-like solutions; their thickness sets the distance scale beyond which physics is string-like rather than particle-like. String degrees of freedom are massless in the sense that excitations on a string can have an arbitrarily low frequency. Non-string degrees of freedom correspond to massive particles and are absent from the low energy spectrum. This article considers only field theories with vortices at low energies. The possible existence of a class of solitons in these vortex theories will be discussed. They are vortex rings: they are localized and finite in energy, and able to carry the quantum numbers of point particles. Rings are thus particle-like solutions of a vortex theory, which is itself a limit of a point particle field theory.

  8. Radiocarbon evidence for annual growth rings in a deep sea octocoral (Primnoa resedaeformis)

    SciTech Connect

    Sherwood, O A; Scott, D B; Risk, M J; Guilderson, T P

    2005-04-05

    The deep-sea gorgonian octocoral Primnoa resedaeformis is distributed throughout the Atlantic and Pacific Oceans at depths of 65-3200 m. It has a two-part skeleton of calcite and gorgonin. Towards the inside of the axial skeleton gorgonin and calcite are deposited in concentric growth rings, similar to tree rings. Colonies were collected from the Northeast Channel (northwest Atlantic Ocean, southwest of Nova Scotia, Canada) from depths of 250-475 m. Radiocarbon was measured in individual rings isolated from sections of each colony, after dissolution of calcite. Each {Delta}{sup 14}C measurement was paired with a ring age determined by three amateur ring counters. The precision of ring counts averaged better than {+-} 2 years. Accurate reconstruction of 20th century bomb-radiocarbon shows that (1) the growth rings are formed annually, (2) the gorgonin is derived from surface particulate organic matter (POM) and (3) useful environmental data are recorded in the organic endoskeletons of deep-sea octocorals. These results support the use of Primnoa resedaeformis as a long-term, high resolution monitor of surface ocean conditions, particularly in temperate and boreal environments where proxy data are lacking.

  9. Double hexagonal graphene ring synthesized using a growth-etching method

    NASA Astrophysics Data System (ADS)

    Liu, Jinyang; Xu, Yangyang; Cai, Hongbing; Zuo, Chuandong; Huang, Zhigao; Lin, Limei; Guo, Xiaomin; Chen, Zhendong; Lai, Fachun

    2016-07-01

    Precisely controlling the layer number, stacking order, edge configuration, shape and structure of graphene is extremely challenging but highly desirable in scientific research. In this report, a new concept named the growth-etching method has been explored to synthesize a graphene ring using the chemical vapor deposition process. The graphene ring is a hexagonal structure, which contains a hexagonal exterior edge and a hexagonal hole in the centre region. The most important concept introduced here is that the oxide nanoparticle derived from annealing is found to play a dual role. Firstly, it acts as a nucleation site to grow the hexagonal graphene domain and then it works as a defect for etching to form a hole. The evolution process of the graphene ring with the etching time was carefully studied. In addition, a double hexagonal graphene ring was successfully synthesized for the first time by repeating the growth-etching process, which not only confirms the validity and repeatability of the method developed here but may also be further extended to grow unique graphene nanostructures with three, four, or even tens of graphene rings. Finally, a schematic model was drawn to illustrate how the double hexagonal graphene ring is generated and propagated. The results shown here may provide valuable guidance for the design and growth of unique nanostructures of graphene and other two-dimensional materials.

  10. Double hexagonal graphene ring synthesized using a growth-etching method.

    PubMed

    Liu, Jinyang; Xu, Yangyang; Cai, Hongbing; Zuo, Chuandong; Huang, Zhigao; Lin, Limei; Guo, Xiaomin; Chen, Zhendong; Lai, Fachun

    2016-08-01

    Precisely controlling the layer number, stacking order, edge configuration, shape and structure of graphene is extremely challenging but highly desirable in scientific research. In this report, a new concept named the growth-etching method has been explored to synthesize a graphene ring using the chemical vapor deposition process. The graphene ring is a hexagonal structure, which contains a hexagonal exterior edge and a hexagonal hole in the centre region. The most important concept introduced here is that the oxide nanoparticle derived from annealing is found to play a dual role. Firstly, it acts as a nucleation site to grow the hexagonal graphene domain and then it works as a defect for etching to form a hole. The evolution process of the graphene ring with the etching time was carefully studied. In addition, a double hexagonal graphene ring was successfully synthesized for the first time by repeating the growth-etching process, which not only confirms the validity and repeatability of the method developed here but may also be further extended to grow unique graphene nanostructures with three, four, or even tens of graphene rings. Finally, a schematic model was drawn to illustrate how the double hexagonal graphene ring is generated and propagated. The results shown here may provide valuable guidance for the design and growth of unique nanostructures of graphene and other two-dimensional materials. PMID:27387556

  11. DYNAMIC STANDARDIZATION OF TREE-RING SERIES

    EPA Science Inventory

    The compound growth function of Warren (W.G. Warren, 1980. ree-Ring Bull. 40:35-44) represented an attempt to develop a model-based approach that standardized tree ring width sequences and was more flexible than the monotonic functions that were then commonly used. hile the idea ...

  12. Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

    SciTech Connect

    Whitesides, Russell; Domin, Dominik; Lester Jr., William A.; Frenklach, Michael

    2007-03-24

    A theoretical study revealed a new reaction pathway, in which a fused five and six-membered ring complex on the zigzag edge of a graphene layer isomerizes to reverse its orientation, or 'flips,' after activation by a gaseous hydrogen atom. The process is initiated by hydrogen addition to or abstraction from the surface complex. The elementary steps of the migration pathway were analyzed using density-functional theory (DFT) calculations to examine the region of the potential energy surface associated with the pathway. The DFT calculations were performed on substrates modeled by the zigzag edges of tetracene and pentacene. Rate constants for the flip reaction were obtained by the solution of energy master equation utilizing the DFT energies, frequencies, and geometries. The results indicate that this reaction pathway is competitive with other pathways important to the edge evolution of aromatic species in high temperature environments.

  13. Mosaic ring chromosome 14 and monosomy 14 presenting with growth retardation, epilepsy, and blepharophimosis.

    PubMed

    Hou, Jia-Woei

    2004-05-01

    Ring chromosomes are rare chromosomal anomalies and usually not stable in nature. Patients carrying ring chromosome have various phenotypes depending on the degree of structural rearrangement. A 1-year-old boy, presenting with hypotonia, blepharophimosis, ptosis, a bulbous nose, mild psychomotor retardation, and epilepsy, was found to have mosaicism of chromosome ring 14 and monosomy 14. His karyotype is described as hitherto unreported mos 46, XY, r(14)(p11.2q32.31 or q32.2)[84]/45, XY,-14[10]/46, XY, dic r(14)[6]. His seizures responded well to phenobarbital. He has marked growth retardation but less serious delays in mental and motor development than those with ring 14 described in the literature. PMID:15366814

  14. Age trends in tree ring growth and isotopic archives: A case study of Pinus sylvestris L. from northwestern Norway

    NASA Astrophysics Data System (ADS)

    Young, Giles H. F.; Demmler, Joanne C.; Gunnarson, BjöRn E.; Kirchhefer, Andreas J.; Loader, Neil J.; McCarroll, Danny

    2011-06-01

    Measurements of tree ring width and relative density have contributed significantly to many of the large-scale reconstructions of past climatic change, but to extract the climate signal it is first necessary to remove any nonclimatic age-related trends. This detrending can limit the lower-frequency climate information that may be extracted from the archive (the "segment length curse"). This paper uses a data set of ring widths, maximum latewood density and stable carbon and oxygen isotopes from 28 annually resolved series of known-age Pinus sylvestris L. trees in northwestern Norway to test whether stable isotopes in tree rings require an equivalent statistical detrending. Results indicate that stable oxygen and carbon isotope ratios from tree rings whose cambial age exceeds c.50 years exhibit no significant age trends and thus may be used to reconstruct environmental variability and physiological processes at this site without the potential loss of low-frequency information associated with detrending.

  15. Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape

    PubMed Central

    Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D.; Tardif, Jacques C.; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

    2015-01-01

    Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems. PMID:26528316

  16. Engelmann spruce tree-ring chronologies from Fraser Experimental Forest, Colorado: Potential for a long-term temperature reconstruction in the central Rocky Mountains

    SciTech Connect

    Brown, P.M.; Shepperd, W.D.

    1995-12-31

    Tree-ring width chronologies from Engelmann spruce at two treeline sites in the central Rocky Mountains contain similar high and low frequency patterns in ring width, indicative of regional climate control on tree growth. Comparisons of annual ring widths with instrumental climate data show relationships with late spring temperature fluctuations on annual to century time scales. Ring width patterns in the earliest dated trees at one of the sites also infers upward migration in treeline at the site around A.D. 1250. No unusual growth increases were seen in recent years, suggesting that these trees have not recorded warmer conditions possibly associated with global climate change.

  17. Effect of plate width on the growth and coalescence of fatigue cracks in plate-to-plate welded T-joints

    SciTech Connect

    Yee, R.; Burns, D.J.; Lambert, S.B.; Lecsek, R.L.; Mohaupt, U.H.

    1995-12-31

    The effect of plate width on the initiation and propagation of fatigue cracks in plate-to-plate T-joints with loading transverse attachment plates and flat fillet-like weld profiles was investigated in a series of constant amplitude fatigue tests. There was no observable effect of plate width on initiation life, propagating life, or total fatigue life, but plate width had a significant effect on crack shape development and crack growth rates. More cracks initiated along the weld toes of wider joints. As a result, the aspect ratios of dominant surface cracks were lower in wider joints, and the dominant surface cracks propagated faster through the thickness of wider base plates. However, there was a greater propensity for edge cracking in narrower specimens because fatigue cracks initiated closer to the free edges of such joints. This offset the faster growth of dominant surface cracks in wider joints so that there was no net effect of plate width on propagation life. A multiple crack linear elastic fracture mechanics model successfully simulated these differences in crack shape development behavior.

  18. An Evaluation of Upper and Lower Pharyngeal Airway Width, Tongue Posture and Hyoid Bone Position in Subjects with Different Growth Patterns

    PubMed Central

    Tarkar, Jaipal Singh; Parashar, Sandeep; Gupta, Garima; Bhardwaj, Preeti; Singh, Atul; Singh, Parul

    2016-01-01

    Introduction It is important to evaluate the position of the hyoid bone in relation to the tongue at the beginning of orthodontic treatment so that during the treatment, its position may be directed hence overall impact on airway could be assessed. Aim The aim of this study was to evaluate the upper and lower pharyngeal airway dimensions, posture of tongue and hyoid bone position in young adults with different growth patterns. Materials and Methods Sample size of the study included 90 post-adolescent subjects, within the age range of 18-32 years. Based on the different growth pattern of the face, subjects were divided into Group I (n=30; average growth pattern), Group II (n=30; horizontal growth pattern) and Group III (n=30; vertical growth pattern). Lateral cephalogram were traced and analysed manually by the same investigator for evaluation of upper and lower pharyngeal airway, tongue posture and hyoid bone position. The intergroup comparison of upper and lower pharyngeal airway dimensions, posture of tongue and hyoid bone was performed with one-way ANOVA test. Results The results showed that upper oropharyngeal widths were significantly different in different facial skeletal patterns (p=0.00). Subjects with vertical skeletal pattern have significantly narrower upper airways than those with horizontal skeletal pattern (p= 0.025). There was significantly higher difference in position of dorsum of the tongue in vertical growth pattern group (p=0.00). The hyoid bone was positioned farther from the mandibular symphysis in brachyfacial subjects, reflected by the larger H-RGN (Hyoid- retrognathion) values compared with the dolichofacial and normal subjects (p=0.044). Conclusion The upper oropharyngeal width was found to be narrower in subjects with vertical growth pattern. The dorsum of the tongue is seen to be placed higher in subjects with vertical growth pattern. The hyoid bone was more inferiorly and posteriorly positioned in subjects with horizontal growth pattern

  19. Reconstructions of spring/summer precipitation for the Eastern Mediterranean from tree-ring widths and its connection to large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Touchan, Ramzi; Xoplaki, Elena; Funkhouser, Gary; Luterbacher, Jürg; Hughes, Malcolm K.; Erkan, Nesat; Akkemik, Ünal; Stephan, Jean

    2005-07-01

    This study represents the first large-scale systematic dendroclimatic sampling focused on developing chronologies from different species in the eastern Mediterranean region. Six reconstructions were developed from chronologies ranging in length from 115 years to 600 years. The first reconstruction (1885-2000) was derived from principal components (PCs) of 36 combined chronologies. The remaining five, 1800-2000, 1700-2000, 1600-2000, 1500-2000 and 1400-2000 were developed from PCs of 32, 18, 14, 9, and 7 chronologies, respectively. Calibration and verification statistics for the period 1931-2000 show good levels of skill for all reconstructions. The longest period of consecutive dry years, defined as those with less than 90% of the mean of the observed May-August precipitation, was 5 years (1591-1595) and occurred only once during the last 600 years. The longest reconstructed wet period was 5 years (1601-1605 and 1751-1755). No long term trends were found in May-August precipitation during the last few centuries. Regression maps are used to identify the influence of large-scale atmospheric circulation on regional precipitation. In general, tree-ring indices are influenced by May-August precipitation, which is driven by anomalous below (above) normal pressure at all atmospheric levels and by convection (subsidence) and small pressure gradients at sea level. These atmospheric conditions also control the anomaly surface air temperature distribution which indicates below (above) normal values in the southern regions and warmer (cooler) conditions north of around 40°N. A compositing technique is used to extract information on large-scale climate signals from extreme wet and dry summers for the second half of the twentieth century and an independent reconstruction over the last 237 years. Similar main modes of atmospheric patterns and surface air temperature distribution related to extreme dry and wet summers were identified both for the most recent 50 years and the last

  20. February-May temperature reconstruction based on tree-ring widths of Abies fargesii from the Shennongjia area in central China

    NASA Astrophysics Data System (ADS)

    Zheng, Yonghong; Shao, Xuemei; Lu, Fei; Li, Yan

    2016-08-01

    February-May temperature strongly affects ecological processes and socio-economics in central China, yet its long-term variability has not been thoroughly assessed due to the shortness of instrumental records. In order to improve the understanding of the regularities of temperature variability in central China, in this study, we present a new tree-ring chronology from the Shengnongjia Mountains in central China which provides a valuable 245-year record of temperature variability. The reconstructed temperature correlated strongly with February-May mean temperature records of the Fangxian meteorological station from AD 1958 to AD 2011, and the derived reconstruction explained 44.5 % of the instrumental temperature variation during this period. The study shows that this region experienced three warm periods and two cool periods, i.e., the major warm periods occurred in AD 1783-1806, AD 1879-1909, and AD 1975 to the present, whereas the cool intervals occurred in AD 1807-1878 and AD 1910-1974. This reconstruction could aid in the evaluation of regional climate variability in subtropical China.

  1. February-May temperature reconstruction based on tree-ring widths of Abies fargesii from the Shennongjia area in central China

    NASA Astrophysics Data System (ADS)

    Zheng, Yonghong; Shao, Xuemei; Lu, Fei; Li, Yan

    2016-01-01

    February-May temperature strongly affects ecological processes and socio-economics in central China, yet its long-term variability has not been thoroughly assessed due to the shortness of instrumental records. In order to improve the understanding of the regularities of temperature variability in central China, in this study, we present a new tree-ring chronology from the Shengnongjia Mountains in central China which provides a valuable 245-year record of temperature variability. The reconstructed temperature correlated strongly with February-May mean temperature records of the Fangxian meteorological station from AD 1958 to AD 2011, and the derived reconstruction explained 44.5 % of the instrumental temperature variation during this period. The study shows that this region experienced three warm periods and two cool periods, i.e., the major warm periods occurred in AD 1783-1806, AD 1879-1909, and AD 1975 to the present, whereas the cool intervals occurred in AD 1807-1878 and AD 1910-1974. This reconstruction could aid in the evaluation of regional climate variability in subtropical China.

  2. February-May temperature reconstruction based on tree-ring widths of Abies fargesii from the Shennongjia area in central China.

    PubMed

    Zheng, Yonghong; Shao, Xuemei; Lu, Fei; Li, Yan

    2016-08-01

    February-May temperature strongly affects ecological processes and socio-economics in central China, yet its long-term variability has not been thoroughly assessed due to the shortness of instrumental records. In order to improve the understanding of the regularities of temperature variability in central China, in this study, we present a new tree-ring chronology from the Shengnongjia Mountains in central China which provides a valuable 245-year record of temperature variability. The reconstructed temperature correlated strongly with February-May mean temperature records of the Fangxian meteorological station from AD 1958 to AD 2011, and the derived reconstruction explained 44.5 % of the instrumental temperature variation during this period. The study shows that this region experienced three warm periods and two cool periods, i.e., the major warm periods occurred in AD 1783-1806, AD 1879-1909, and AD 1975 to the present, whereas the cool intervals occurred in AD 1807-1878 and AD 1910-1974. This reconstruction could aid in the evaluation of regional climate variability in subtropical China. PMID:26759230

  3. Role of re-growth interface preparation process for spectral line-width reduction of single InAs site-controlled quantum dots.

    PubMed

    Herranz, Jesús; Wewior, Lukasz; Alén, Benito; Fuster, David; González, Luisa; González, Yolanda

    2015-05-15

    We present growth and optical characterization measurements of single InAs site-controlled quantum dots (SCQDs) grown by molecular beam epitaxy on GaAs (001) patterned substrates by atomic force microscopy oxidation lithography. InAs SCQDs directly grown on the patterned surface were used as a seed layer and strain template for the nucleation of optically active single InAs SCQDs. The preservation of the initial geometry of the engraved pattern motifs after the re-growth interface preparation process, the lack of buffer layer growth prior to InAs seed layer deposition and the development of suitable growth conditions provide us an improvement of the SCQDs' active layer optical properties while retaining a high ratio of single occupation (89%). In this work a fivefold reduction of the average optical line-width from 870 μeV to 156 μeV for InAs SCQDs located 15 nm from the re-growth interface is obtained by increasing the temperature of the initial thermal treatment step of the re-growth interface from 490 °C to 530 °C. PMID:25895541

  4. Long Tree-Ring Chronologies Provide Evidence of Recent Tree Growth Decrease in a Central African Tropical Forest

    PubMed Central

    Battipaglia, Giovanna; Zalloni, Enrica; Castaldi, Simona; Marzaioli, Fabio; Cazzolla- Gatti, Roberto; Lasserre, Bruno; Tognetti, Roberto; Marchetti, Marco; Valentini, Riccardo

    2015-01-01

    It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2. PMID:25806946

  5. Responses of tree-ring growth and crop yield to drought indices in the Shanxi province, North China.

    PubMed

    Sun, Junyan; Liu, Yu

    2014-09-01

    In this paper, we analyze the relationships among the tree-ring chronology, meteorological drought (precipitation), agricultural drought (Palmer Drought Severity Index PDSI), hydrological drought (runoff), and agricultural data in the Shanxi province of North China. Correlation analyses indicate that the tree-ring chronology is significantly correlated with all of the drought indices during the main growing season from March to July. Sign test analyses further indicate that the tree-ring chronology shows variation similar to that of the drought indices in both high and low frequencies. Comparisons of the years with narrow tree rings to the severe droughts reflected in all three indices from 1957 to 2008 reveal that the radial growth of the trees in the study region can accurately record the severe drought for which all three indices were in agreement (1972, 1999, 2000, and 2001). Comparisons with the dryness/wetness index indicate that tree-ring growth can properly record the severe droughts in the history. Correlation analyses among agricultural data, tree-ring chronology, and drought indices indicate that the per-unit yield of summer crops is relatively well correlated with the agricultural drought, as indicated by the PDSI. The PDSI is the climatic factor that significantly influences both tree growth and per-unit yield of summer crops in the study region. These results indicate that the PDSI and tree-ring chronology have the potential to be used to monitor and predict the yield of summer crops. Tree-ring chronology is an important tool for drought research and for wider applications in agricultural and hydrological research. PMID:24162181

  6. Btk29A-mediated tyrosine phosphorylation of armadillo/β-catenin promotes ring canal growth in Drosophila oogenesis.

    PubMed

    Hamada-Kawaguchi, Noriko; Nishida, Yasuyoshi; Yamamoto, Daisuke

    2015-01-01

    Drosophila Btk29A is the ortholog of mammalian Btk, a Tec family nonreceptor tyrosine kinase whose deficit causes X-linked agammaglobulinemia in humans. The Btk29AficP mutation induces multiple abnormalities in oogenesis, including the growth arrest of ring canals, large intercellular bridges that allow the flow of cytoplasm carrying maternal products essential for embryonic development from the nurse cells to the oocyte during oogenesis. In this study, inactivation of Parcas, a negative regulator of Btk29A, was found to promote Btk29A accumulation on ring canals with a concomitant increase in the ring canal diameter, counteracting the Btk29AficP mutation. This mutation markedly reduced the accumulation of phosphotyrosine on ring canals and in the regions of cell-cell contact, where adhesion-supporting proteins such as DE-cadherin and β-catenin ortholog Armadillo (Arm) are located. Our previous in vitro and in vivo analyses revealed that Btk29A directly phosphorylates Arm, leading to its release from DE-cadherin. In the present experiments, immunohistological analysis revealed that phosphorylation at tyrosine 150 (Y150) and Y667 of Arm was diminished in Btk29AficP mutant ring canals. Overexpression of an Arm mutant with unphosphorylatable Y150 inhibited ring canal growth. Thus Btk29A-induced Y150 phosphorylation is necessary for the normal growth of ring canals. We suggest that the dissociation of tyrosine-phosphorylated Arm from DE-cadherin allows dynamic actin to reorganize, leading to ring canal expansion and cell shape changes during the course of oogenesis. PMID:25803041

  7. [Paleoclimate of La Guajira, Colombia; by the growth rings of Capparis odoratissima (Capparidaceae)].

    PubMed

    Ramírez, Jorge Andrés; Ignacio del Valle, Jorge

    2011-09-01

    There is great concern about the effect of climate change in arid and subarid areas of the tropics. Climate change combined with other anthropogenic activities such as deforestation, fires and over-grazing can accelerate their degradation and, consequently, the increases in losses of biological and economic productivity. Climate models, both local and global, predict that rainfall in the arid Peninsula of La Guajira in the Colombian Caribbean would be reduced and temperature would be increased as a result of climate change. However, as there are only suitable climate records since 1972, it is not possible to verify if, indeed, this is happening. To try to verify the hypothesis of reducing rainfall and rising temperatures we developed a growth ring chronology of Capparis odoratissima in the Middle Peninsula of La Guajira with 17 trees and 45 series which attain 48 years back. We use standard dendrochronological methods that showed statistically significant linear relationship with local climatic variables such as air temperature, sea surface temperature (SST), annual precipitation and wind speed; we also reach to successful relationship of the chronology with global climatic variables as the indices SOI and MEI of the ENSO phenomenon. The transfer functions estimated with the time series (1955 and 2003) do not showed statistically significant trends, indicating that during this period of time the annual precipitation or temperatures have not changed. The annual nature of C. odoratissima growth rings, the possibility of cross-dated among the samples of this species, and the high correlation with local and global climatic variables indicate a high potential of this species for dendrochronological studies in this part of the American continent. PMID:22017140

  8. Reconstruction of Pacific salmon abundance from riparian tree-ring growth.

    PubMed

    Drake, D C; Naiman, Robert J

    2007-07-01

    We use relationships between modern Pacific salmon (Oncorhynchus spp.) escapement (migrating adults counted at weirs or dams) and riparian tree-ring growth to reconstruct the abundance of stream-spawning salmon over 150-350 years. After examining nine sites, we produced reconstructions for five mid-order rivers and four salmon species over a large geographic range in the Pacific Northwest: chinook (O. tschwatcha) in the Umpqua River, Oregon, USA; sockeye (O. nerka) in Drinkwater Creek, British Columbia, Canada; pink (O. gorbuscha) in Sashin Creek, southeastern Alaska, USA; chum (O. keta) in Disappearance Creek, southeastern Alaska, USA; and pink and chum in the Kadashan River, southeastern Alaska, USA. We first derived stand-level, non-climatic growth chronologies from riparian trees using standard dendroecology methods and differencing. When the chronologies were compared to 18-55 years of adult salmon escapement we detected positive, significant correlations at five of the nine sites. Regression models relating escapement to tree-ring growth at the five sites were applied to the differenced chronologies to reconstruct salmon abundance. Each reconstruction contains unique patterns characteristic of the site and salmon species. Reconstructions were validated by comparison to local histories (e.g., construction of dams and salmon canneries) and regional fisheries data such as salmon landings and aerial surveys and the Pacific Decadal Oscillation climate index. The reconstructions capture lower-frequency cycles better than extremes and are most useful for determination and comparison of relative abundance, cycles, and the effects of interventions. Reconstructions show lower population cycle maxima in both Umpqua River chinook and Sashin Creek pink salmon in recent decades. The Drinkwater Creek reconstruction suggests that sockeye abundance since the mid-1990s has been 15-25% higher than at any time since 1850, while no long-term deviations from natural cycles are

  9. Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

    USGS Publications Warehouse

    Foster, Jane R.; D'Amato, Anthony W.; Bradford, John B.

    2014-01-01

    Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

  10. An ecological study on air pollution: Changes in annual ring growth of the Japanese cedar and prevalence of respiratory symptoms in schoolchildren in Japanese rural districts

    SciTech Connect

    Kagamimori, S.; Katoh, T.; Naruse, Y.; Kakiuchi, H.; Matsubara, I.; Kasuya, M.; Kawano, S. )

    1990-06-01

    The effect of air pollution caused by oil-fired electricity-generating stations on the annual ring growth of the Japanese cedar (Cryptomeria japonica, D. Don) and prevalence of respiratory symptoms in schoolchildren were investigated. By retrospective analysis the annual ring growth has been demonstrated to show good agreement with the general trend in air pollution. In addition it was found to be related to the prevalence of respiratory symptoms. The reduction in annual ring growth and increase in the prevalence of respiratory symptoms followed a deterioration in air pollution. Following upgrading of the power station and an improvement in air pollution, the annual ring growth and prevalence of respiratory symptoms showed opposite changes, respectively. Concerning the latter, the prevalence of wheezing and respiratory symptoms associated with school absence in schoolchildren with a positive skin test to house dust extract showed a closer correlation with the annual ring growth when compared with those who had never had a positive skin test.

  11. Increase in platinum group elements in Mexico City as revealed from growth rings of Taxodium mucronatum ten.

    PubMed

    Morton-Bermea, Ofelia; Beramendi-Orosco, Laura; Martínez-Reyes, Ángeles; Hernández-Álvarez, Elizabeth; González-Hernández, Galia

    2016-02-01

    Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 μg kg(-1)), followed by Rh (0.28-36.81 μg kg(-1)) and Pt (0.106-7.21 μg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments. PMID:25903068

  12. Parameterization of a multiagent system for roof edge detection: an application to growth ring detection on fish otoliths

    NASA Astrophysics Data System (ADS)

    Guillaud, Anne; Benzinou, Abdessalam; Troadec, Herve; Rodin, Vincent; Le Bihan, Jean

    2000-03-01

    In this paper we present a method of segmentation using a multiagent system, and an application to fish otolith growth ring detection. The otoliths images are composed of alternative concentric dark and light rings, the number of which increases with the age of the fish. Up to now, the identification of growth rings, for age estimation, is routinely achieved by human readers, but this task is tedious and depends on the reader's subjectivity. The system proposed here is composed of several agents whose individual task is to detect local extremes on a grayscale image. For this aim the agents are provided with sensors on the gray levels of the image. By computing the mean gray level of two sensors placed in front of it, the agent, if it searches for light rings (respectively dark) will decide to turn in the direction of the lighter (respectively darker) sensor. The path of the agents has been tested as a roof edge detector, using the Canny criteria: good detection, good localization, and low multiple response, in order to choose the best parameters ruling the agents behavior, according to the image structures. Tests have been first achieved on synthetic images, and then on otoliths images.

  13. Element concentrations in growth rings of trees near an abandoned wood-preserving plant site at Jackson, Tennessee

    USGS Publications Warehouse

    Yanosky, T.M.; Carmichael, J.K.

    1993-01-01

    Multielement analysis was performed on individual annual rings of trees growing at and near an abandoned wood-preserving plant site in Jackson, Tennessee, that operated from the early 1930's until 1981. Numerous organic compounds associated with the wood-preserving process have been detected in soils, ground water, and surface water within much of the site. Tree-ring investigations were conducted prior to investigations of ground water downgradient from the site to determine if trees preserved an areal and temporal record of contaminant movement into offsite areas. Increment cores were collected from trees on the abandoned plant site, in downgradient areas west and south of the site, and at two locations presumably unaffected by contamination from the site. Multielement analysis by proton-induced X-ray emission was performed on 5 to 15 individual growth rings from each of 34 trees that ranged in age from about 5 to 50 years. Concentrations of 16 elements were evaluated by analyzing average concentrations within the 1987, 1989, and 1990 rings of all trees; analyzing element-concentration trends along entire core radii; and analyzing element correlations between and among trees. Concentrations of some nutrients and trace metals were elevated in the outermost sapwood rings of some trees that grow south and southwest of the most contaminated part of the site; small trees on the main part of the site and larger trees to the west generally contained fewer rings with elevated concentrations, particularly of trace metals. Concentrations of several elements elevated in tree rings also were elevated in water samples collected from the reach of a stream that flows near the southwestern part of the site. Multielement analysis of each ring of a willow growing along the southern boundary of the site detected extremely large concentrations of chromium, nickel, and iron in rings that formed in 1986 and thereafter. Relative increases in the concentrations of these elements also

  14. No evidence for consistent long-term growth stimulation of 13 tropical tree species: results from tree-ring analysis.

    PubMed

    Groenendijk, Peter; van der Sleen, Peter; Vlam, Mart; Bunyavejchewin, Sarayudh; Bongers, Frans; Zuidema, Pieter A

    2015-10-01

    The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate-vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2 -fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest-stand level, but insights into species-specific growth changes - that ultimately determine community-level responses - are lacking. Here, we analyse species-specific growth changes on a centennial scale, using growth data from tree-ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size-class isolation) growth-trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8-10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large-scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous

  15. Population differentiation in tree-ring growth response of white fir (Abies concolor) to climate: Implications for predicting forest responses to climate change

    SciTech Connect

    Jensen, D.B.

    1993-10-01

    Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four common gardens in the Sierra Nevada of California. For each population, tree-ring growth was modelled as a function of precipitation and degree-day sums. Tree-ring growth under three scenarios of doubled C0{sub 2} climates was estimated.

  16. Stabilization of actin bundles by a dynamin 1/cortactin ring complex is necessary for growth cone filopodia.

    PubMed

    Yamada, Hiroshi; Abe, Tadashi; Satoh, Ayano; Okazaki, Nana; Tago, Shota; Kobayashi, Kinue; Yoshida, Yumi; Oda, Yoshiya; Watanabe, Masami; Tomizawa, Kazuhito; Matsui, Hideki; Takei, Kohji

    2013-03-01

    Dynamin GTPase, a key molecule in endocytosis, mechanically severs the invaginated membrane upon GTP hydrolysis. Dynamin functions also in regulating actin cytoskeleton, but the mechanisms are yet to be defined. Here we show that dynamin 1, a neuronal isoform of dynamin, and cortactin form ring complexes, which twine around F-actin bundles and stabilize them. By negative-staining EM, dynamin 1-cortactin complexes appeared as "open" or "closed" rings depending on guanine nucleotide conditions. By pyrene actin assembly assay, dynamin 1 stimulated actin assembly in mouse brain cytosol. In vitro incubation of F-actin with both dynamin 1 and cortactin led to the formation of long and thick actin bundles, on which dynamin 1 and cortactin were periodically colocalized in puncta. A depolymerization assay revealed that dynamin 1 and cortactin increased the stability of actin bundles, most prominently in the presence of GTP. In rat cortical neurons and human neuroblastoma cell line, SH-SY5Y, both dynamin 1 and cortactin localized on actin filaments and the bundles at growth cone filopodia as revealed by immunoelectron microscopy. In SH-SY5Y cell, acute inhibition of dynamin 1 by application of dynamin inhibitor led to growth cone collapse. Cortactin knockdown also reduced growth cone filopodia. Together, our results strongly suggest that dynamin 1 and cortactin ring complex mechanically stabilizes F-actin bundles in growth cone filopodia. Thus, the GTPase-dependent mechanochemical enzyme property of dynamin is commonly used both in endocytosis and regulation of F-actin bundles by a dynamin 1-cortactin complex. PMID:23467367

  17. Understanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributions

    NASA Astrophysics Data System (ADS)

    Min, Kyungguk; Liu, Kaijun

    2016-04-01

    Fast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (fp) with ∂fp(v⊥)/∂v⊥>0. Two typical types of distributions with such features are ring and shell velocity distributions. Both have been used in studies of ion Bernstein instabilities and fast magnetosonic waves, but the differences between instabilities driven by the two types of distributions have not been thoroughly addressed. The present study uses linear kinetic theory to examine and understand these differences. It is found that the growth rate pattern is primarily determined by the cyclotron resonance condition and the structure of the velocity distribution in gyroaveraged velocity space. For ring-driven Bernstein instabilities, as the parallel wave number (k∥) increases, the discrete unstable modes approximately follow the corresponding proton cyclotron harmonic frequencies while they become broader in frequency space. At sufficiently large k∥, the neighboring discrete modes merge into a continuum. In contrast, for shell-driven Bernstein instabilities, the curved geometry of the shell velocity distribution in gyroaveraged velocity space results in a complex alternating pattern of growth and damping rates in frequency and wave number space and confines the unstable Bernstein modes to relatively small k∥. In addition, when k∥ increases, the unstable modes are no longer limited to the proton cyclotron harmonic frequencies. The local growth rate peak near an exact harmonic at small k∥ bifurcates into two local peaks on both sides of the harmonic when k∥ becomes large.

  18. Confined growth of carbon nanoforms in one-dimension by fusion of anthracene rings inside the pores of MCM-41

    NASA Astrophysics Data System (ADS)

    Bosch-Navarro, Concha; Coronado, Eugenio; Martí-Gastaldo, Carlos; Amorós, Pedro

    2014-06-01

    We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host.We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host. Electronic supplementary information (ESI) available: Synthesis details, SEM and additional HR-TEM images, FT-IR spectra, EDAX microanalysis and pore distribution of loaded MCM41@anth. See DOI: 10.1039/c3nr06669j

  19. Seasonal climate signals from multiple tree ring metrics: A case study of Pinus ponderosa in the upper Columbia River Basin

    NASA Astrophysics Data System (ADS)

    Dannenberg, Matthew P.; Wise, Erika K.

    2016-04-01

    Projected changes in the seasonality of hydroclimatic regimes are likely to have important implications for water resources and terrestrial ecosystems in the U.S. Pacific Northwest. The tree ring record, which has frequently been used to position recent changes in a longer-term context, typically relies on signals embedded in the total ring width of tree rings. Additional climatic inferences at a subannual temporal scale can be made using alternative tree ring metrics such as earlywood and latewood widths and the density of tree ring latewood. Here we examine seasonal precipitation and temperature signals embedded in total ring width, earlywood width, adjusted latewood width, and blue intensity chronologies from a network of six Pinus ponderosa sites in and surrounding the upper Columbia River Basin of the U.S. Pacific Northwest. We also evaluate the potential for combining multiple tree ring metrics together in reconstructions of past cool- and warm-season precipitation. The common signal among all metrics and sites is related to warm-season precipitation. Earlywood and latewood widths differ primarily in their sensitivity to conditions in the year prior to growth. Total and earlywood widths from the lowest elevation sites also reflect cool-season moisture. Effective correlation analyses and composite-plus-scale tests suggest that combining multiple tree ring metrics together may improve reconstructions of warm-season precipitation. For cool-season precipitation, total ring width alone explains more variance than any other individual metric or combination of metrics. The composite-plus-scale tests show that variance-scaled precipitation reconstructions in the upper Columbia River Basin may be asymmetric in their ability to capture extreme events.

  20. [Anatomic characterization of growth-rings in 80 potential tree species for dendrocronological studies in the Central Forest, Perú].

    PubMed

    Beltrán Gutiérrez, Lizandro Adal; Valencia Ramos, Gina Mariela

    2013-09-01

    The knowledge about the existence of annual tree rings in tropical trees, which was already found at the beginning of the last century, was ignored by many scientists for a long time. Wood samples of 80 tree species from seven different sites belonging to Satipo and Chanchamayo provinces in Central Forest, Perú. Wood slices were taken at 1.30 m height, following the Peruvian Technical Norms (NTP) 251-008, COPANT norms 30:1-019 and IAWA (1989). Results showed that 24 of the 80 tree species analyzed showed a potential for dendrocronological studies, 25 had problems for growth-rings analysis, and 31 did not have potential. The problems most frequently found were: barely visible or irregular ring growth, parenchyma bands and multiseriate rays difficult to be identified in rings growth. The "T" Student test showed that the significant variation in vessel and fiber diameters between growth zones (Early-wood and late-wood) of species with potential for dendrocronology, do have a periodic cells production, so is possible to suggest the annual formation of each growth-ring. However, those species without potential to dendrocronology may be influenced by of a lot of factors, such as biotic and abiotic conditions of environment, as well as the genetic aspect of each species. PMID:24027905

  1. Relationship between the growth of the ring current and the interplanetary quantity. [solar wind energy-magnetospheric coupling parameter correlation with substorm AE index

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    Akasofu (1979) has reported that the interplanetary parameter epsilon correlates reasonably well with the magnetospheric substorm index AE; in the first approximation, epsilon represents the solar wind coupled to the magnetosphere. The correlation between the interplanetary parameter, the auroral electrojet index and the ring current index is examined for three magnetic storms. It is shown that when the interplanetary parameter exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, producing an abnormal growth of the ring current index.

  2. Crystal growth mechanisms in miarolitic cavities in the Lake George ring complex and vicinity, Colorado

    USGS Publications Warehouse

    Kile, D.E.; Eberl, D.D.

    1999-01-01

    The Crystal Peak area of the Pikes Peak batholith, near Lake George in central Colorado, is world-renowned for its crystals of amazonite (the blue-green variety of microcline) and smoky quartz. Such crystals, collected from individual miarolitic pegmatites, have a remakably small variation in crystal size within each pegmatite, and the shapes of plots of their crystal size distributions (CSDs) are invariably lognormal or close to lognormal in all cases. These observations are explained by a crystal growth mechanism that was governed initially by surface-controlled kinetics, during which crystals tended to grow larger in proportion to their size, thereby establishing lognormal CSDs. Surface-controlled growth was followed by longer periods of supply controlled growth, during which growth rate was predominantly size-independent, consequently preserving the lognormal shapes of the CSDs and the small size variation. The change from surface- to supply controlled growth kinetics may have resulted from an increasing demand for nutrients that exceeded diffusion limitations of the system. The proposed model for crystal growth in this locality appears to be common in the geologic record, and can be used with other information, such as isotopic data, to deduce physico-chemical conditions during crystal formation.

  3. Environmental Assessment of EL Paso's Upper and Lower Valley Canal Systems Using Tree Ring Analysis

    NASA Astrophysics Data System (ADS)

    Garcia, S.; Espinosa, S.

    2012-12-01

    Dendrochronology, or tree-ring dating, is the science of dating of past environmental events or climatic changes utilizing tree ring growth patterns. The width of the rings of certain species of trees (i.e. Populus fremontii) are dependent on regional precipitation levels or the abundance of local water sources. Therefore thick rings are produced during wet years and, inversely, narrow rings during dry years. This growth can also be affected by, and date, such factors as slope gradient, soil properties, temperature and snow accumulation. The more a tree's rate of growth has been limited by such environmental factors, the more variation in ring to ring growth will be present and the higher probability of dating such factors. Trees showing a lack of ring width variability rings have generally constant environmental or climatic conditions and indicate that no environmental or climatic changes have occurred. Our study will examine the tree ring of the Rio Grande Cottonwood (Populus fremontii), due to its short life span, rapid growth, and wide spread occurrence in our proposed study area. Our study area will encompass sites along the Rio Grande, canals and residential areas in El Paso County. Our first goal will be to investigate the possibility of identifying environmental contaminants stored within various xylem tissue members of the tree rings and ascertaining dates and regional concentrations of heavy metals and therefore identifying possible sources of contamination. The second goal will be to use dendrochronology to identify and date any growth stress or impedance due to the effects of over pumping, canal lining, and flood control methods in the study area.

  4. Emittance growth in heavy ion rings due to effects of space charge and dispersion

    SciTech Connect

    Barnard, J.J., LLNL

    1998-06-03

    We review the derivation of moment equations which include the effects of space charge and dispersion in bends first presented in ref [1]. These equations generalize the familiar envelope equations to include the dispersive effects of bends. We review the application of these equations to the calculation of the change in emittance resulting from a sharp transition from a straight section to a bend section, using an energy conservation constraint. Comparisons of detailed 2D and 3D simulations of intense beams in rings using the WARP code (refs [2,3]) are made with results obtained from the moment equations. We also compare the analysis carried out in ref [1], to more recent analyses, refs [4,5]. We further examine self-consistent distributions of beams in bends and discuss the relevance of these distributions to the moment equation formulation.

  5. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  6. On the Breakup of Patterened Nanoscale Copper Rings into Nanoparticles: Competing Instability and Transport Mechanisms

    SciTech Connect

    Fowlkes, Jason Davidson; Wu, Yeuyeng; Rack, P. D.; Diez, Javier A; Kondic, Lou

    2010-01-01

    Nanolithographically patterned copper rings were synthesized, and the self-assembly of the rings into ordered nanoparticle/nanodrop arrays was accomplished via nanosecond pulsed laser heating above the melt threshold. The resultant length scale was correlated to the transport and instability growths that occur during the liquid lifetime of the melted copper rings. For 13-nm-thick rings, a change in the nanoparticle spacing with the ring width is attributed to a transition from a Raleigh-Plateau instability to a thin film instability because of competition between the cumulative transport and instability timescales. To explore the competition between instability mechanisms further, we carried out experiments with 7-nm-thick rings. In agreement with the theoretical predictions, these rings break up in both the azimuthal and radial directions, confirming that a simple hydrodynamic model captures the main features of the processes leading to the breakup.

  7. miR-762 promotes porcine immature Sertoli cell growth via the ring finger protein 4 (RNF4) gene

    PubMed Central

    Ma, Changping; Song, Huibin; Yu, Lei; Guan, Kaifeng; Hu, Pandi; Li, Yang; Xia, Xuanyan; Li, Jialian; Jiang, Siwen; Li, Fenge

    2016-01-01

    A growing number of reports have revealed that microRNAs (miRNAs) play critical roles in spermatogenesis. Our previous study showed that miR-762 is differentially expressed in immature and mature testes of Large White boars. Our present data shows that miR-762 directly binds the 3′ untranslated region (3′UTR) of ring finger protein 4 (RNF4) and down-regulates RNF4 expression. A single nucleotide polymorphism (SNP) in the RNF4 3′UTR that is significantly associated with porcine sperm quality traits leads to a change in the miR-762 binding ability. Moreover, miR-762 promotes the proliferation of and inhibits apoptosis in porcine immature Sertoli cells, partly by accelerating DNA damage repair and by reducing androgen receptor (AR) expression. Taken together, these findings suggest that miR-762 may play a role in pig spermatogenesis by regulating immature Sertoli cell growth. PMID:27596571

  8. miR-762 promotes porcine immature Sertoli cell growth via the ring finger protein 4 (RNF4) gene.

    PubMed

    Ma, Changping; Song, Huibin; Yu, Lei; Guan, Kaifeng; Hu, Pandi; Li, Yang; Xia, Xuanyan; Li, Jialian; Jiang, Siwen; Li, Fenge

    2016-01-01

    A growing number of reports have revealed that microRNAs (miRNAs) play critical roles in spermatogenesis. Our previous study showed that miR-762 is differentially expressed in immature and mature testes of Large White boars. Our present data shows that miR-762 directly binds the 3' untranslated region (3'UTR) of ring finger protein 4 (RNF4) and down-regulates RNF4 expression. A single nucleotide polymorphism (SNP) in the RNF4 3'UTR that is significantly associated with porcine sperm quality traits leads to a change in the miR-762 binding ability. Moreover, miR-762 promotes the proliferation of and inhibits apoptosis in porcine immature Sertoli cells, partly by accelerating DNA damage repair and by reducing androgen receptor (AR) expression. Taken together, these findings suggest that miR-762 may play a role in pig spermatogenesis by regulating immature Sertoli cell growth. PMID:27596571

  9. Growth of ring ripple in a collisionless plasma in relativistic-ponderomotive regime and its effect on stimulated Raman backscattering process

    SciTech Connect

    Rawat, Priyanka; Purohit, Gunjan; Gauniyal, Rakhi

    2014-06-15

    A theoretical and numerical study has been made of the propagation of a ring rippled laser beam in collisionless plasma with dominant relativistic ponderomotive nonlinearity and its effect on the excitation of electron plasma wave and stimulated Raman backscattering process. The growth of ring ripple, riding on an intense Gaussian laser beam in plasma has also been studied. A paraxial-ray and WKB approximation has been invoked to understand the nature of propagation of the ring rippled Gaussian laser beam in plasma, electron plasma wave and back reflectivity under the influence of both nonlinearities. The growth rate and focusing of a ring rippled beam is found to be considerably affected by the power of the main beam and the phase angle between the electric vectors of the main beam and the ring ripple. It has also been observed that the focusing is released by the coupling of relativistic and ponderomotive nonlinearities, which significantly affected the dynamics of the excitation of electron plasma wave and back reflectivity of stimulated Raman scattering (SRS). Due to the strong coupling between ring rippled laser beam and the excited electron plasma wave, back reflectivity of SRS is enhanced. It has been observed from the computational results that the effect of the increased intensity leads to suppression of SRS back reflectivity. The results have been presented for established laser and plasma parameters.

  10. Voyager 2 and the Uranian rings

    SciTech Connect

    Porco, C.C.

    1986-12-01

    Voyager 2 data on the Uranian disk system are presented and examined. The disk system consists of nine narrow rings, ranging in width from a few km to about 100 km. The Uranian rings are eccentric, inclined to the planet's equatorial plane, and precessing. The Uranian ring characteristics detected in the Voyager data are described and compared with those of the Saturn rings. The origin and maintenance of the rings are discussed, and the particle distribution in the ring system is studied.

  11. Plasma deposited rider rings for hot displacer

    DOEpatents

    Kroebig, Helmut L.

    1976-01-01

    A hot cylinder for a cryogenic refrigerator having two plasma spray deposited rider rings of a corrosion and abrasion resistant material provided in the rider ring grooves, wherein the rider rings are machined to the desired diameter and width after deposition. The rider rings have gas flow flats machined on their outer surface.

  12. Tree-ring based history of climate and disease in western Oregon forests

    EPA Science Inventory

    Annual tree-ring width data are often used to make inferences of past climate and the spatiotemporal climate-growth relationships. However, the climatic signal may be confounded with non-climatic signals such as disease or pest disturbances at unknown times in the past. Signal e...

  13. Design and synthesis of benzoylphenylureas with fluorinated substituents on the aniline ring as insect growth regulators.

    PubMed

    Sun, Ranfeng; Liu, Yuxiu; Zhang, Yonglin; Xiong, Lixia; Wang, Qingmin

    2011-03-23

    Enormous numbers of synthetic fluorine-containing compounds have been widely used in a variety of fields, especially in drug and pesticide design. To find novel insect growth regulators, a series of benzoylphenylureas with fluorinated substituents were designed and synthesized. The results of larvicidal activities of those novel fluoro-substituted benzoylphenylureas against oriental armyworm and mosquito revealed that most compounds exhibited excellent activities. It is worth mentioning that compounds 3 and 6 exhibited higher activities against oriental armyworm and mosquito than commercial Hexaflumuron. It can be further seen that the insecticidal activities would increase significantly by introducing fluorinated substituents into the structure of the designed benzoylphenylureas. PMID:21366291

  14. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  15. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas-fir

    EPA Science Inventory

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible...

  16. Studies and calculations of transverse emittance growth in high-energy proton storage rings

    SciTech Connect

    Mane, S.R.; Jackson, G.

    1989-03-01

    In the operation of proton-antiproton colliders, an important goal is to maximize the integrated luminosity. During such operations in the Fermilab Tevatron, the transverse beam emittances were observed to grow unexpectedly quickly, thus causing a serious reduction of the luminosity. We have studied this phenomenon experimentally and theoretically. A formula for the emittance growth rate, due to random dipole kicks, is derived. In the experiment, RF phase noise of known amplitude was deliberately injected into the Tevatron to kick the beam randomly, via dispersion at the RF cavities. Theory and experiment are found to agree reasonably well. We also briefly discuss the problem of quadrupole kicks. 14 refs., 2 figs., 3 tabs.

  17. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth

    PubMed Central

    Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

    2015-01-01

    Intercellular bridges called “ring canals” (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs’ anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin–containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs’ anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin–dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth. PMID:26424451

  18. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth.

    PubMed

    Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

    2015-10-13

    Intercellular bridges called "ring canals" (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs' anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin-containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs' anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin-dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth. PMID:26424451

  19. Narrow Width Pentaquarks

    NASA Astrophysics Data System (ADS)

    Buccella, F.; Sorba, P.

    A general study of pentaquarks built with four quarks in a L=1 state and an antiquark in S-wave shows that several of such states are forbidden by a selection rule, which holds in the limit of flavor symmetry, to decay into a baryon and a meson final state. We identify the most promising /line{10} multiplet for the classification of the Θ+ and Ξ-- particles recently discovered with the prediction of a narrow width for both of them.

  20. Resonances and resonance widths

    SciTech Connect

    Collins, T.

    1986-05-01

    Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances.

  1. Long range correlations in tree ring chronologies of the USA: Variation within and across species

    NASA Astrophysics Data System (ADS)

    Bowers, M. C.; Gao, J. B.; Tung, W. W.

    2013-02-01

    Abstract Tree <span class="hlt">ring</span> <span class="hlt">width</span> data are among the best proxies for reconstructing past temperature and precipitation records. The discovery of fractal scaling and long-memory in meteorological and hydrological signals motivates us to investigate such properties in tree <span class="hlt">ring</span> chronologies. Detrended fluctuation analysis and adaptive fractal analysis are utilized to estimate the Hurst parameter values of 697 tree <span class="hlt">ring</span> chronologies from the continental United States. We find significant differences in the Hurst parameter values across the 10 species studied in the work. The long-range scaling relations found here suggest that the behavior of tree <span class="hlt">ring</span> <span class="hlt">growth</span> observed in a short calibration period may be similar to the general behavior of tree <span class="hlt">ring</span> <span class="hlt">growth</span> in a much longer period, and therefore, the limited calibration period may be more useful than originally thought. The variations of the long-range correlations within and across species may be further explored in future to better reconstruct paleoclimatic records.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086956','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086956"><span id="translatedtitle">Effects of Changing Stomatal <span class="hlt">Width</span> in A Red Pine Forest on Soil Water Content, Leaf Water Potential, Bole Diameter, and <span class="hlt">Growth</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Turner, Neil C.; Waggoner, Paul E.</p> <p>1968-01-01</p> <p>Spraying a 16 meter tall stand of red pine (Pinus resinosa Ait.) with 10−3 m phenylmercuric acetate in early June and again in mid-July resulted in the water use between June 1 and October 25 being reduced by almost 10%. It was demonstrated that this was caused by an increase in the leaf resistance with partial stomatal closure, which reduced absolute water potential in the needles by 1 to 3 bars in the middle of the day. Smaller demands were made upon the reserves of water in the bole of the tree as shown by the smaller bole contraction in the treated trees. Although needle length and dry weight were unaffected by the spray, radial <span class="hlt">growth</span> was reduced by approximately 32%. The dependence of leaf resistance on light intensity is shown, and its independence from leaf water potential discussed. PMID:16656870</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730015432','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730015432"><span id="translatedtitle">Diatomic predissociation line <span class="hlt">widths</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Child, M. S.</p> <p>1973-01-01</p> <p>Predissociation by rotation and curve crossing in diatomic molecules is discussed. The pattern of predissociation line <span class="hlt">widths</span> is seen as providing a highly sensitive yardstick for the determination of unknown potential curves. In addition, the computation of such a pattern for given potential curves is considered a matter of routine, unless the predissociation happens to occur from an adiabatic potential curve. Analytic formulas are used to provide physical insight into the details of the predissociation pattern, to the extent that a direct inversion procedure is developed for determination of the repulsive potential curves for Type 1 predissociations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B11C0449K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B11C0449K"><span id="translatedtitle">Model-based analysis on the relationship between production and tree-<span class="hlt">ring</span> <span class="hlt">growth</span> in Japanese conifer-hardwood mixed forests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koide, D.; Ito, A.</p> <p>2015-12-01</p> <p>Forest productivity is a basic and important component of terrestrial material flow and its importance increases according to recent climate warming and the increase in atmospheric-CO2 concentrations. Forest productivity study progresses through measurement by eddy-covariance data from flux tower and prediction by terrestrial ecosystem models. However, flux tower observation has spatiotemporal bias and limitation. On the other hand, tree-<span class="hlt">ring</span> data have a close connection with forest ecosystem productivity. Compared to flux tower observation, we can collect tree-<span class="hlt">ring</span> data from a larger number of sites and longer time scales. Comparisons between tree-<span class="hlt">ring</span> observation and model-estimated productivity is important to reveal underlying mechanisms of forest ecosystem productivity and <span class="hlt">growth</span> in wide spatiotemporal scale. This study aimed at revealing the relationship between temporal changes in tree-<span class="hlt">ring</span> data and estimated forest ecosystem productivity in Japanese conifer-hardwood mixed forest. We also addressed climatic bias in the relationship by comparing between sites at different climatic conditions. Tree-<span class="hlt">ring</span> data of Sakhalin spruce (Picea glehnii) were obtained from the International Tree <span class="hlt">Ring</span> Data Bank. Six sites on the Hokkaido island (northern island of Japan) were selected for the present analysis. The Vegetation Integrated SImulator for Trace gasses (VISIT) model was validated by comparing with carbon flux data from Asia flux network sites. Past climatic parameters were obtained from ERA-20C reanalysis data from the European Center for Medium-range Weather Forecasts. Correlation between basal area increment and net ecosystem productivity was highest in the coldest site but this correlation weakened in warmer sites. This result implies that long-term <span class="hlt">growth</span> trend was mainly restricted by cold stress associated with productivity reduction in colder sites but this factor is less important and other factors exert influence in warmer sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDA33003K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDA33003K&link_type=ABSTRACT"><span id="translatedtitle">Coffee-<span class="hlt">ring</span> effect beyond the dilute limit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jin Young; Ryu, Seul-A.; Kim, Hyungdae; Kim, Joon Heon; Park, Jung Su; Park, Yong Seok; Oh, Jeong Su; Weon, Byung Mook</p> <p>2015-11-01</p> <p>The coffee-<span class="hlt">ring</span> effect, which is a natural generation of outward capillary flows inside drying coffee drops, is valid at the dilute limit of initial solute concentrations. If the solute is not dilute, the <span class="hlt">ring</span> deposit is forced to have a non-zero <span class="hlt">width</span>; higher initial concentration leads to a wider <span class="hlt">ring</span>. Here we study the coffee-<span class="hlt">ring</span> effect in the dense limit by demonstrating differences with various initial coffee concentrations from 0.1% to 60%. The coffee drops with high initial concentrations of real coffee particles show interesting evaporation dynamics: dense coffee drops tend to evaporate slowly. This result is different from the classic coffee-<span class="hlt">ring</span> effect in the dilute limit. We suppose that the slow evaporation of dense coffee drops is associated with the <span class="hlt">ring</span> <span class="hlt">growth</span> dynamics. The coffee-<span class="hlt">ring</span> effect becomes more significant in modern technologies such as self-assembly of nanoparticles, ink-jet printing, painting and ceramics. The complexity in evaporation dynamics of colloidal fluids would be able to be understood by expanding the coffee-<span class="hlt">ring</span> effects in the dilute as well as the dense limits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011IAUS..271..102W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011IAUS..271..102W"><span id="translatedtitle">On the formation of <span class="hlt">ring</span> galaxies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Yu-Ting; Jiang, Ing-Guey</p> <p>2011-08-01</p> <p>The formation scenario of <span class="hlt">ring</span> galaxies is addressed in this paper. We focus on the P-type <span class="hlt">ring</span> galaxies presented in Madore, Nelson & Petrillo (2009), particularly on the axis-symmetric ones. Our simulations show that a <span class="hlt">ring</span> can form through the collision of disc and dwarf galaxies, and the locations, <span class="hlt">widths</span>, and density contrasts of the <span class="hlt">ring</span> are well determined. We find that a <span class="hlt">ring</span> galaxy such as AM 2302-322 can be produced by this collision scenario.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256514&keyword=Geography&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=65002399&CFTOKEN=44109874','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=256514&keyword=Geography&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=65002399&CFTOKEN=44109874"><span id="translatedtitle">Statistical methodologies for tree-<span class="hlt">ring</span> research to understand the climate-<span class="hlt">growth</span> relationships over time and space</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The International Tree-<span class="hlt">Ring</span> Database is a valuable resource for studying climate change and its effects on terrestrial ecosystems over time and space. We examine the statistical methods in current use in dendroclimatology and dendroecology to process the tree-<span class="hlt">ring</span> data and make ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/971178','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/971178"><span id="translatedtitle">Wavelength-tunable optical <span class="hlt">ring</span> resonators</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.</p> <p>2009-11-10</p> <p>Optical <span class="hlt">ring</span> resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk <span class="hlt">ring</span> resonators, or as open-<span class="hlt">ring</span> resonators with an optical waveguide having a <span class="hlt">width</span> that varies adiabatically. Electrical and mechanical connections to the open-<span class="hlt">ring</span> resonators are made near a maximum <span class="hlt">width</span> of the optical waveguide to minimize losses and thereby provide a high resonator Q. The <span class="hlt">ring</span> resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1021901','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1021901"><span id="translatedtitle">Wavelength-tunable optical <span class="hlt">ring</span> resonators</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.</p> <p>2011-07-19</p> <p>Optical <span class="hlt">ring</span> resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk <span class="hlt">ring</span> resonators, or as open-<span class="hlt">ring</span> resonators with an optical waveguide having a <span class="hlt">width</span> that varies adiabatically. Electrical and mechanical connections to the open-<span class="hlt">ring</span> resonators are made near a maximum <span class="hlt">width</span> of the optical waveguide to minimize losses and thereby provide a high resonator Q. The <span class="hlt">ring</span> resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1413742S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1413742S"><span id="translatedtitle">iTREE: Long-term variability of tree <span class="hlt">growth</span> in a changing environment - identifying physiological mechanisms using stable C and O isotopes in tree <span class="hlt">rings</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siegwolf, R. T. W.; Buchmann, N.; Frank, D.; Joos, F.; Kahmen, A.; Treydte, K.; Leuenberger, M.; Saurer, M.</p> <p>2012-04-01</p> <p>Trees play are a critical role in the carbon cycle - their photosynthetic assimilation is one of the largest terrestrial carbon fluxes and their standing biomass represents the largest carbon pool of the terrestrial biosphere. Understanding how tree physiology and <span class="hlt">growth</span> respond to long-term environmental change is pivotal to predict the magnitude and direction of the terrestrial carbon sink. iTREE is an interdisciplinary research framework to capitalize on synergies among leading dendroclimatologists, plant physiologists, isotope specialists, and global carbon cycle modelers with the objectives of reducing uncertainties related to tree/forest <span class="hlt">growth</span> in the context of changing natural environments. Cross-cutting themes in our project are tree <span class="hlt">rings</span>, stable isotopes, and mechanistic modelling. We will (i) establish a European network of tree-<span class="hlt">ring</span> based isotope time-series to retrodict interannual to long-term tree physiological changes, (ii) conduct laboratory and field experiments to adapt a mechanistic isotope model to derive plant physiological variables from tree-<span class="hlt">ring</span> isotopes, (iii) implement this model into a dynamic global vegetation model, and perform subsequent model-data validation exercises to refine model representation of plant physiological processes and (iv) attribute long-term variation in tree <span class="hlt">growth</span> to plant physiological and environmental drivers, and identify how our refined knowledge revises predictions of the coupled carbon-cycle climate system. We will contribute to i) advanced quantifications of long-term variation in tree <span class="hlt">growth</span> across Central Europe, ii) novel long-term information on key physiological processes that underlie variations in tree <span class="hlt">growth</span>, and iii) improved carbon cycle models that can be employed to revise predictions of the coupled carbon-cycle climate system. Hence iTREE will significantly contribute towards a seamless understanding of the responses of terrestrial ecosystems to long-term environmental change, and ultimately</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4024743','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4024743"><span id="translatedtitle">Arctic tree <span class="hlt">rings</span> as recorders of variations in light availability</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Stine, A. R.; Huybers, P.</p> <p>2014-01-01</p> <p>Annual <span class="hlt">growth</span> <span class="hlt">ring</span> variations in Arctic trees are often used to reconstruct surface temperature. In general, however, the <span class="hlt">growth</span> of Arctic vegetation is limited both by temperature and light availability, suggesting that variations in atmospheric transmissivity may also influence tree-<span class="hlt">ring</span> characteristics. Here we show that Arctic tree-<span class="hlt">ring</span> density is sensitive to changes in light availability across two distinct phenomena: explosive volcanic eruptions (P<0.01) and the recent epoch of global dimming (P<0.01). In each case, the greatest response is found in the most light-limited regions of the Arctic. Essentially no late 20th century decline in tree-<span class="hlt">ring</span> density relative to temperature is seen in the least light-limited regions of the Arctic. Consistent results follow from analysis of tree-<span class="hlt">ring</span> <span class="hlt">width</span> and from individually analysing each of seven tree species. Light availability thus appears an important control, opening the possibility for using tree <span class="hlt">rings</span> to reconstruct historical changes in surface light intensity. PMID:24805143</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5179339','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5179339"><span id="translatedtitle"><span class="hlt">Width</span> of nonlinear resonance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ohnuma, S.</p> <p>1984-03-01</p> <p>Two approximations are made, one essential and the other not so essential but convenient to keep the analytical treatment manageable: (1) Only one nonlinear resonance is considered at a time so that the treatment is best suited when the tune is close to one resonance only. To improve this approximation, one must go to the next order which involves a canonical transformation of dynamical variables. Analytical treatment of more than one resonance is not possible for general cases. (2) In the formalism using the action-angle variables, the Hamiltonian can have terms which are independent of the angle variables. These terms are called phase-independent terms or shear terms. The tune is then a function of the oscillation amplitudes. In the lowest-order treatment, the (4N)-pole components but not the (4N + 2)-pole components contribute to this dependence. In deriving the resonance <span class="hlt">width</span> analytically, one ignores these terms in the Hamiltonian for the sake of simplicity. If these are retained, one needs at least three extra parameters and the analytical treatment becomes rather unwieldy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6008759','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6008759"><span id="translatedtitle">Planetary <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Greenberg, R.; Brahic, A.</p> <p>1984-01-01</p> <p>Among the topics discussed are the development history of planetary <span class="hlt">ring</span> research, the view of planetary <span class="hlt">rings</span> in astronomy and cosmology over the period 1600-1900, the characteristics of the <span class="hlt">ring</span> systems of Saturn and Uranus, the ethereal <span class="hlt">rings</span> of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of <span class="hlt">ring</span> particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary <span class="hlt">rings</span>. Also discussed are planetary <span class="hlt">ring</span> waves, <span class="hlt">ring</span> particle dynamics in resonances, the dynamics of narrow <span class="hlt">rings</span>, the origin and evolution of planetary <span class="hlt">rings</span>, the solar nebula and planetary disk, future studies of the planetary <span class="hlt">rings</span> by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary <span class="hlt">ring</span> dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RaPC...95..346G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RaPC...95..346G"><span id="translatedtitle">Biomonitoring of environmental pollution using <span class="hlt">growth</span> tree <span class="hlt">rings</span> of Tipuana tipu: Quantification by synchrotron radiation total reflection X-ray fluorescence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geraldo, S. M.; Canteras, F. B.; Moreira, S.</p> <p>2014-02-01</p> <p>Currently, many studies use the bioindicators to qualitatively and/or quantitatively measure pollution. The analyses of tree <span class="hlt">growth</span> <span class="hlt">rings</span> represent one such bioindicator as changes in the environment are often recorded as impressions in the wood. The main objective of the present study is to examine the <span class="hlt">growth</span> <span class="hlt">rings</span> of Tipuana tipu - a member of the Leguminosae family that is native to Argentina and Bolivia and was introduced in Brazil as an ornamental plant - for potentially toxic elements. T. tipu is one of the most common trees in the urban landscape of Sao Paulo city and would provide an accurate reflection of environment changes. Tree <span class="hlt">ring</span> samples previously dated using Synchrotron Radiation Total Reflection X-ray Fluorescence were collected from strategic locations in Sao Paulo. These locations include Piracicaba (SP) that has little access and small flow traffic and the campus of the University of São Paulo. Some trace elements present concentrations higher than considered as normal in some periods. In São Paulo city, samples collected from the campus of University of São Paulo (Butantã), showed the highest toxicity, with concentrations above the tolerable limit for the elements: Cr, Cu, and Pb. For the samples collected in Piracicaba city, one sample presented highest concentrations for the majority of the elements when compared to the other four samples collected at the same place, exceeding the toxicity limits for: Cr, Ni, Cu, and Pb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780045340&hterms=occult&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doccult','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780045340&hterms=occult&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doccult"><span id="translatedtitle">Uranus and the shape of elliptical <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lucke, R. L.</p> <p>1978-01-01</p> <p>It is reported that when the star SAO158687 passed behind the Uranus system, its light was occulted twice by the epsilon (fifth) <span class="hlt">ring</span> of the planet. The first part of the <span class="hlt">ring</span> to occult was about 100 km wide and the second part was about 40 km wide. The variable <span class="hlt">width</span> of the <span class="hlt">ring</span> is accounted for by differences in the orbital eccentricities of the individual particles composing the <span class="hlt">ring</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25644125','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25644125"><span id="translatedtitle"><span class="hlt">Growth</span> patterns and age validation from otolith <span class="hlt">ring</span> deposition in New Zealand longfin eels Anguilla dieffenbachii recaptured after 10 years at large.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beentjes, M P; Jellyman, D J</p> <p>2015-03-01</p> <p>In 1998, 9500 juvenile New Zealand longfin eels Anguilla dieffenbachii (mean total length, LT , 42 cm) captured from the lower Clutha River were transferred upstream to Lake Hawea, a high-country oligotrophic lake in the same catchment where recruitment of juvenile eels has been prevented by hydroelectric dams since 1958. A total of 2010 of the transferred A. dieffenbachii were tagged with coded wire tags. Ten years later in 2008, the A. dieffenbachii population in Lake Hawea was sampled resulting in 399 recaptures (distinguishable by the presence of tags and by LT from the remnant resident population of large old A. dieffenbachii) of the 1998 transfers; 79 (19·2%) of the recaptured fish had tags compared with 21·3% at release, indicating good tag retention and low mortality due to tagging. All recaptured tagged A. dieffenbachii were female. Mean annual <span class="hlt">growth</span> over the 10 years since release was 3·80 cm year(-1) for all recaptures and 3·65 cm year(-1) for tag recaptures, and both were significantly greater than the estimate of 2·38 cm year(-1) at release. After release, mean condition (K) increased significantly (P < 0·001) for all recaptures and tag recaptures. Annual length <span class="hlt">growth</span> increment was linear. Tag recaptures showed significant increases in somatic <span class="hlt">growth</span> rate post-transfer, and otoliths from the 2008 recaptured A. dieffenbachii were examined to see whether any similar enhanced <span class="hlt">growth</span> after transfer was incorporated into the otolith structure that would serve as a date stamp. Measurement of otolith <span class="hlt">ring</span> radii indicated that an increase in the radius occurred on most otoliths corresponding to the year after transfer. Because there was 9 years of completed <span class="hlt">growth</span> following the observed <span class="hlt">growth</span> inflection on the otoliths, this was strong evidence that opaque <span class="hlt">rings</span> were formed annually. PMID:25644125</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=PIA02241&hterms=saturns+rings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsaturns%2Brings','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=PIA02241&hterms=saturns+rings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsaturns%2Brings"><span id="translatedtitle">Saturn's <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>When seen from the unlit side, the <span class="hlt">rings</span> of Saturn present a much different appearance from that familiar to telescopic observers. Relatively opaque areas like the B <span class="hlt">Ring</span> turn black, while lightly populated zones, such as the C <span class="hlt">Ring</span> and the Cassini Division, prove to excellent diffuse transmitters of sunlight. The A <span class="hlt">Ring</span>, with intermediate opacity, is at an intermediate level of brightness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/EJ1054944.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/EJ1054944.pdf"><span id="translatedtitle">The <span class="hlt">Width</span> of a Proof</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Hanna, Gila</p> <p>2014-01-01</p> <p>This paper's aim is to discuss the concept of <span class="hlt">width</span> of a proof put forward by Timothy Gowers. It explains what this concept means and attempts to show how it relates to other concepts discussed in the existing literature on proof and proving. It also explores how the concept of <span class="hlt">width</span> of a proof might be used productively in the mathematics…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JESS..117..637R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JESS..117..637R"><span id="translatedtitle">Tree-<span class="hlt">ring</span> analysis of teak ( Tectona grandis L.F.) in central India and its relationship with rainfall and moisture index</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ram, Somaru; Borgaonkar, H. P.; Sikder, A. B.</p> <p>2008-10-01</p> <p>Tree-<span class="hlt">ring-width</span> index chronologies of teak ( Tectona grandis L.F.) from three sites in central India have been studied for their dendroclimatic potential. The existence of good correlation among the three site chronologies indicates the influence of common forcing factor to the tree <span class="hlt">growth</span> of the region. Tree <span class="hlt">growth</span> and climate relationship based on correlation analysis revealed the important contribution of moisture index and rainfall rather than the direct influence of the temperature on tree <span class="hlt">growth</span> during different seasons. Significant positive relationship of moisture index and rainfall during the monsoon months as well as on the annual scale with tree-<span class="hlt">ring</span> <span class="hlt">width</span> variations over the region indicates the important role of moisture availability at the root zone. The results suggest that the teak tree-<span class="hlt">ring</span> chronologies can be used as high resolution proxy for past precipitation and moisture level in the environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/753092','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/753092"><span id="translatedtitle">Phase <span class="hlt">width</span> reduction project summary</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clark, D.J.; Xie, Z.Q.; McMahan, M. A.</p> <p>1999-11-01</p> <p>The purpose of the phase <span class="hlt">width</span> reduction project, 1993--96, was to reduce the phase <span class="hlt">width</span> of the 88-Inch Cyclotron beam on target from 5--10 ns to 1--2 ns for certain experiments, such as Gammasphere, which use time-of-flight identification. Since reducing the phase <span class="hlt">width</span> also reduces beam intensity, tuning should be done to also optimize the transmission. The Multi-turn Collimator slits in the cyclotron center region were used to collimate the early turns radially, thus reducing the phase <span class="hlt">width</span> from about 5 ns to 1--2 ns FWHM for a Gammasphere beam. The effect of the slits on phase <span class="hlt">width</span> was verified with a Fast Faraday Cup and with particle and gamma-ray detectors in the external beamline.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P12A..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P12A..03C"><span id="translatedtitle">Saturn's <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuzzi, J. N.</p> <p>2014-12-01</p> <p>The <span class="hlt">rings</span> are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major <span class="hlt">ring</span> science progress over the mission to date, and describe new observations planned for Cassini's final three years. <span class="hlt">Ring</span> Composition and particle sizes: The <span class="hlt">rings</span> are nearly all water ice with no other ices - so why are they reddish? The C <span class="hlt">Ring</span> and Cassini Division are "dirtier" than the more massive B and A <span class="hlt">Rings</span>, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. <span class="hlt">Ring</span> structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main <span class="hlt">ring</span> divisions, the C <span class="hlt">Ring</span> plateau structures, and the B <span class="hlt">Ring</span> irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A <span class="hlt">ring</span>. Rubble pile ringmoons just outside the <span class="hlt">rings</span> may escaped from the <span class="hlt">rings</span>, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the <span class="hlt">rings</span>: Comet fragments set the <span class="hlt">rings</span> to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the <span class="hlt">Rings</span>: The <span class="hlt">ring</span> mass and bombardment play key roles. The <span class="hlt">ring</span> mass is well known everywhere but in the B <span class="hlt">Ring</span> (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient <span class="hlt">rings</span>, of which the current <span class="hlt">ring</span> is just a shadow. During its last three years, the Cassini tour profile will allow entirely new</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820029397&hterms=Currie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCurrie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820029397&hterms=Currie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCurrie"><span id="translatedtitle">Saturn's E <span class="hlt">ring</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baum, W. A.; Kreidl, T.; Westphal, J. A.; Danielson, G. E.; Seidelmann, P. K.; Pascu, D.; Currie, D. G.</p> <p>1981-01-01</p> <p>Observations of the tenuous E <span class="hlt">ring</span> of Saturn made by an earth-based CCD system at the time of the <span class="hlt">ring</span>-plane crossing of March 1980 are presented. The observations were made with the CCD system attached to the 1.8-m Perkins reflector at Lowell Observatory using a pupil mask behind a focal plane mask to suppress telescopic diffraction. Photometric analysis of the CCD images reveal the edge-on brightness profile of the <span class="hlt">ring</span>, beginning at a distance of 3 Saturn radii, to peak sharply in the vicinity of the orbit of Enceladus at about 4 Saturn radii, then decrease to a distance of over 8 Saturn radii. In addition, beyond Enceladus, the edge-on <span class="hlt">width</span> of the <span class="hlt">ring</span> is observed to increase with radial distance, reaching nearly 5 arcsec at 7 Saturn radii. Observations suggest, on the one hand, that the E <span class="hlt">ring</span> is associated with Enceladus and possibly represents material ejected from the satellite, and on the other, that the <span class="hlt">ring</span> is at an early stage in its evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6093088','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6093088"><span id="translatedtitle">Possible red spruce decline: Contributions of tree-<span class="hlt">ring</span> analysis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Van Deusen, P.C. ); Reams, G.A. ); Cook, E.R. )</p> <p>1991-01-01</p> <p>Debate continues about the cause of apparent unprecedented decreases in <span class="hlt">ring</span> <span class="hlt">width</span> at all elevations, and increasing levels of mortality at high elevations, in red spruce (Picea rubens) stands in the northeastern United States. These <span class="hlt">growth</span> and mortality trends are often used as evidence of red spruce decline, but the possibility remains that they may be occurring naturally. Two hypotheses are being used to explain the causes of red spruce <span class="hlt">growth</span> reduction across its range and increased levels of standing dead at some high-elevation sites. This article summarizes the basic evidence used by advocates of these hypotheses and discusses the strengths of their arguments. The information presented is based primarily on tree-<span class="hlt">ring</span> studies sponsored by the Forest Response Program, which is part of the National Acid Precipitation Assessment Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApSS..329..137X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApSS..329..137X"><span id="translatedtitle">Facile solvothermal synthesis of abnormal <span class="hlt">growth</span> of one-dimensional ZnO nanostructures by <span class="hlt">ring</span>-opening reaction of polyvinylpyrrolidone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, G.; Wang, X. L.; Liu, G. Z.</p> <p>2015-02-01</p> <p>Abnormal <span class="hlt">growth</span> of one-dimensional (1-D) ZnO nanostructures (NSs) have been accomplished with the assistance of polyvinylpyrrolidone (PVP) under a super high alkaline alcoholic solvothermal condition. The products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The effect of synthetic conditions, such as reaction temperature and the addition of PVP, on the morphologies of ZnO products were investigated. The results show that PVP molecules had the significant role in the transformation of morphologies of ZnO NSs ranging from nanorods, nanoparticles to pyramids, as well as flower-like assembly features. The possible <span class="hlt">growth</span> mechanism of ZnO pyramids was proposed based on <span class="hlt">ring</span>-opening reaction of PVP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=PIA01976&hterms=2o&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D2o','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=PIA01976&hterms=2o&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D2o"><span id="translatedtitle">Uranus <span class="hlt">rings</span> and two moons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1986-01-01</p> <p>Voyager 2 has discovered two 'shepherd' satellites associated with the <span class="hlt">rings</span> of Uranus. The two moons -- designated 1986U7 and 1986U8 -- are seen here on either side of the bright epsilon <span class="hlt">ring</span>; all nine of the known Uranian <span class="hlt">rings</span> are visible. The image was taken Jan. 21, 1986, at a distance of 4.1 million kilometers (2.5 million miles) and resolution of about 36 km (22 mi). The image was processed to enhance narrow features. The epsilon <span class="hlt">ring</span> appears surrounded by a dark halo as a result of this processing; occasional blips seen on the <span class="hlt">ring</span> are also artifacts. Lying inward from the epsilon <span class="hlt">ring</span> are the delta, gamma and eta <span class="hlt">rings</span>; then the beta and alpha <span class="hlt">rings</span>; and finally the barely visible 4, 5 and 6 <span class="hlt">rings</span>. The <span class="hlt">rings</span> have been studied since their discovery in 1977, through observations of how they diminish the light of stars they pass in front of. This image is the first direct observation of all nine <span class="hlt">rings</span> in reflected sunlight. They range in <span class="hlt">width</span> from about 100 km (60 mi) at the widest part of the epsilon <span class="hlt">ring</span> to only a few kilometers for most of the others. The discovery of the two <span class="hlt">ring</span> moons 1986U7 and 1986U8 is a major advance in our understanding of the structure of the Uranian <span class="hlt">rings</span> and is in good agreement with theoretical predictions of how these narrow <span class="hlt">rings</span> are kept from spreading out. Based on likely surface brightness properties, the moons are of roughly 2O- and 3O-km diameter, respectively. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JHyd..529..640C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JHyd..529..640C"><span id="translatedtitle">Total water storage dynamics derived from tree-<span class="hlt">ring</span> records and terrestrial gravity observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Creutzfeldt, Benjamin; Heinrich, Ingo; Merz, Bruno</p> <p>2015-10-01</p> <p>For both societal and ecological reasons, it is important to understand past and future subsurface water dynamics but estimating subsurface water storage is notoriously difficult. In this pilot study, we suggest the reconstruction of subsurface water dynamics by a multi-disciplinary approach combining hydrology, dendrochronology and geodesy. In a first step, nine complete years of high-precision gravimeter observations are used to estimate water storage changes in the subsurface at the Geodetic Observatory Wettzell in the Bavarian Forest, Germany. The record is extended to 63 years by calibrating a hydrological model against the 9 years of gravimeter observations. The relationship between tree-<span class="hlt">ring</span> <span class="hlt">growth</span> and water storage changes is evaluated as well as that between tree-<span class="hlt">ring</span> <span class="hlt">growth</span> and supplementary hydro-meteorological data. Results suggest that tree-<span class="hlt">ring</span> <span class="hlt">growth</span> is influenced primarily by subsurface water storage. Other variables related to the overall moisture status (e.g., Standardized Precipitation Index, Palmer Drought Severity Index, streamflow) are also strongly correlated with tree-<span class="hlt">ring</span> <span class="hlt">width</span>. While these indices are all indicators of water stored in the landscape, water storage changes of the subsurface estimated by depth-integral measurements give us the unique opportunity to directly reconstruct subsurface water storage dynamics from records of tree-<span class="hlt">ring</span> <span class="hlt">width</span>. Such long reconstructions will improve our knowledge of past water storage variations and our ability to predict future developments. Finally, knowing the relationship between subsurface storage dynamics and tree-<span class="hlt">ring</span> <span class="hlt">growth</span> improves the understanding of the different signal components contained in tree-<span class="hlt">ring</span> chronologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://medlineplus.gov/ency/article/007318.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/007318.htm"><span id="translatedtitle">Vascular <span class="hlt">ring</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular <span class="hlt">ring</span>; Birth defect heart - vascular <span class="hlt">ring</span> ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=PIA02224&hterms=Neptune&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNeptune','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=PIA02224&hterms=Neptune&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNeptune"><span id="translatedtitle">Neptune's <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>This 591-second exposure of the <span class="hlt">rings</span> of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main <span class="hlt">rings</span> are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint <span class="hlt">ring</span> and the faint band which extends smoothly from the <span class="hlt">ring</span> roughly halfway between the two bright <span class="hlt">rings</span>. Both of these newly discovered <span class="hlt">rings</span> are broad and much fainter than the two narrow <span class="hlt">rings</span>. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright <span class="hlt">rings</span> have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21699247','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21699247"><span id="translatedtitle"><span class="hlt">Ring</span>-opening copolymerization of maleic anhydride with epoxides: a chain-<span class="hlt">growth</span> approach to unsaturated polyesters.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>DiCiccio, Angela M; Coates, Geoffrey W</p> <p>2011-07-20</p> <p>We report the <span class="hlt">ring</span>-opening copolymerization of maleic anhydride with a variety of epoxides catalyzed by a chromium(III) salen complex. Quantitative isomerization of the cis-maleate form of all polymers affords the trans-fumarate analogues. Addition of chain transfer reagents yields low M(n), narrow PDI polymer samples. This method provides access to a range of new unsaturated polyesters with versatile functionality, as well as the first synthesis of high molecular weight poly(propylene fumarate). PMID:21699247</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22308169','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22308169"><span id="translatedtitle"><span class="hlt">Width</span> dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan; Rousseau, Olivier; Otani, YoshiChika</p> <p>2014-10-28</p> <p>We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying <span class="hlt">ring</span> <span class="hlt">width</span>. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the <span class="hlt">ring</span> <span class="hlt">width</span>. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest <span class="hlt">ring</span>, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the <span class="hlt">ring</span> <span class="hlt">width</span> decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest <span class="hlt">ring</span>, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different <span class="hlt">ring</span> <span class="hlt">width</span> as obtained from micromagnetic analysis and supported by magnetic force microscopy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatSR...3E1276S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatSR...3E1276S"><span id="translatedtitle">Gravitational Vortices And Clump Formation In Saturn's F <span class="hlt">ring</span> During An Encounter With Prometheus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sutton, Phil J.; Kusmartsev, Feodor V.</p> <p>2013-02-01</p> <p>Saturn <span class="hlt">rings</span> are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-<span class="hlt">ring</span> have been attributed to encounters by Prometheus on the F <span class="hlt">ring</span>, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-<span class="hlt">ring</span> structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated <span class="hlt">growth</span> and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km <span class="hlt">width</span> and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23429480','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23429480"><span id="translatedtitle">Gravitational vortices and clump formation in Saturn's F <span class="hlt">ring</span> during an encounter with Prometheus.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sutton, Phil J; Kusmartsev, Feodor V</p> <p>2013-01-01</p> <p>Saturn <span class="hlt">rings</span> are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-<span class="hlt">ring</span> have been attributed to encounters by Prometheus on the F <span class="hlt">ring</span>, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-<span class="hlt">ring</span> structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated <span class="hlt">growth</span> and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km <span class="hlt">width</span> and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet. PMID:23429480</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3572473','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3572473"><span id="translatedtitle">Gravitational Vortices And Clump Formation In Saturn's F <span class="hlt">ring</span> During An Encounter With Prometheus</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sutton, Phil J.; Kusmartsev, Feodor V.</p> <p>2013-01-01</p> <p>Saturn <span class="hlt">rings</span> are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-<span class="hlt">ring</span> have been attributed to encounters by Prometheus on the F <span class="hlt">ring</span>, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-<span class="hlt">ring</span> structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated <span class="hlt">growth</span> and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km <span class="hlt">width</span> and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet. PMID:23429480</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/60987','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/60987"><span id="translatedtitle">Tree-<span class="hlt">rings</span> and climate: Implications for Great Basin paleoenvironmental studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Graybill, D.A.; Rose, M.R.; Nials, F.L.</p> <p>1994-12-31</p> <p>The Quaternary Sciences Center of the Desert Research Institute is currently conducting a multi-phased study of floral, faunal, and geomorphic response to long- and short-term climate change and extremes in assessing Yucca Mountain`s suitability as a high-level nuclear waste repository. Preliminary results of these studies indicate synchronous responses in late Holocene tree-<span class="hlt">ring</span>, palynology and geomorphic records. A tree-<span class="hlt">ring</span> chronology for paleoclimatic reconstruction is developed by collection of multiple cores from 20-60 living trees and a similar number of dead trees in a climate-sensitive location. Samples are cross-dated and every <span class="hlt">growth</span> layer in each specimen is measured to the nearest .001 mm. The measured <span class="hlt">ring</span> <span class="hlt">width</span> series potentially contain a variety of climatic, biological, and anthropogenic signals. Each <span class="hlt">ring</span> <span class="hlt">width</span> series is subjected to a numerical standarization procedure that removes an age-related biological <span class="hlt">growth</span> trend, reduces endogeneous and exogenous stand disturbance factors, and maximizes any climatic signal that is present. Each of these empirically defined components can be graphically portrayed and subjected to further analyses. The geophysical signal analysis techniques involved in the standarized protocol are well-documented and established. The final result is a tree-<span class="hlt">ring</span> chronology that represents regional paleoclimatic variability over the time represented by the sample population.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5825072','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5825072"><span id="translatedtitle">Radiation densitometry in tree-<span class="hlt">ring</span> analysis: a review and procedure manual</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Parker, M.L.; Taylor, F.G.; Doyle, T.W.; Foster, B.E.; Cooper, C.; West, D.C.</p> <p>1985-01-01</p> <p>An x-ray densitometry of wood facility is being established by the Environmental Sciences Division, Oak Ridge Natioanl Laboratory (ORNL). The objective is to apply tree-<span class="hlt">ring</span> data to determine whether or not there is a fertilizer effect on tree <span class="hlt">growth</span> from increased atmospheric carbon dioxide since the beginning of the industrial era. Intra-<span class="hlt">ring</span> <span class="hlt">width</span> and density data, including <span class="hlt">ring</span>-mass will be detemined from tree-<span class="hlt">ring</span> samples collected from sites located throughout the United States and Canada. This report is designed as a guide to assist ORNL scientists in building the x-ray densitometry system. The history and development of x-ray densitometry in tree-<span class="hlt">ring</span> research is examined and x-ray densitometry is compared with other techniques. Relative wood and tree characteristics are described as are environmental and genetic factors affecting tree <span class="hlt">growth</span> responses. Methods in x-ray densitometry are examined in detail and the techniques used at four operating laboratories are described. Some ways that dendrochronology has been applied in dating, in wood quality, and environmental studies are presented, and a number of tree-<span class="hlt">ring</span> studies in Canada are described. An annotated bibliography of radiation densitometry in tree-<span class="hlt">ring</span> analysis and related subjects is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100042208','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100042208"><span id="translatedtitle">Stacked Corrugated Horn <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sosnowski, John B.</p> <p>2010-01-01</p> <p>This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the <span class="hlt">width</span> and conventional machining is not practical. The horn is divided into easily machined, individual <span class="hlt">rings</span> with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into <span class="hlt">rings</span> that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal <span class="hlt">ring</span> is dipped in liquid nitrogen, then nested in the previous, larger <span class="hlt">ring</span>. The <span class="hlt">ring</span> is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011BGD.....811089T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011BGD.....811089T&link_type=ABSTRACT"><span id="translatedtitle">Process based model sheds light on climate signal of mediterranean tree <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Touchan, R.; Shishov, V. V.; Meko, D. M.; Nouiri, I.; Grachev, A.</p> <p>2011-11-01</p> <p>We use the process-based VS (Vaganov-Shashkin) model to investigate whether a regional Pinus halapensis tree-<span class="hlt">ring</span> chronology from Tunisia can be simulated as a function of climate alone by employing a biological model linking day length and daily temperature and precipitation (AD 1959-2004) from a climate station to <span class="hlt">ring-width</span> variations. We use two periods to calibrate (1982-2004) and verify (1959-1981) the model. We have obtained highly significant positive correlation between the residual chronology and estimated <span class="hlt">growth</span> curve (r = 0.76 p < 0.001). The model shows that the average duration of the growing season is 191 days. On average, soil moisture limits tree-<span class="hlt">ring</span> <span class="hlt">growth</span> for 128 days and temperature for 63 days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3423803','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3423803"><span id="translatedtitle">Fluctuations of cambial activity in relation to precipitation result in annual <span class="hlt">rings</span> and intra-annual <span class="hlt">growth</span> zones of xylem and phloem in teak (Tectona grandis) in Ivory Coast</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dié, Agathe; Kitin, Peter; Kouamé, François N'Guessan; Van den Bulcke, Jan; Van Acker, Joris; Beeckman, Hans</p> <p>2012-01-01</p> <p>Background and Aims Teak forms xylem <span class="hlt">rings</span> that potentially carry records of carbon sequestration and climate in the tropics. These records are only useful when the structural variations of tree <span class="hlt">rings</span> and their periodicity of formation are known. Methods The seasonality of <span class="hlt">ring</span> formation in mature teak trees was examined via correlative analysis of cambial activity, xylem and phloem formation, and climate throughout 1·5 years. Xylem and phloem differentiation were visualized by light microscopy and scanning electron microscopy. Key Results A 3 month dry season resulted in semi-deciduousness, cambial dormancy and formation of annual xylem <span class="hlt">growth</span> <span class="hlt">rings</span> (AXGRs). Intra-annual xylem and phloem <span class="hlt">growth</span> was characterized by variable intensity. Morphometric features of cambium such as cambium thickness and differentiating xylem layers were positively correlated. Cambium thickness was strongly correlated with monthly rainfall (R2 = 0·7535). In all sampled trees, xylem <span class="hlt">growth</span> zones (XGZs) were formed within the AXGRs during the seasonal development of new foliage. When trees achieved full leaf, the xylem in the new XGZs appeared completely differentiated and functional for water transport. Two phloem <span class="hlt">growth</span> <span class="hlt">rings</span> were formed in one growing season. Conclusions The seasonal formation pattern and microstructure of teak xylem suggest that AXGRs and XGZs can be used as proxies for analyses of the tree history and climate at annual and intra-annual resolution. PMID:22805529</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GPC...133...65P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GPC...133...65P"><span id="translatedtitle">Wet season precipitation during the past century reconstructed from tree-<span class="hlt">rings</span> of a tropical dry forest in Southern Ecuador</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pucha-Cofrep, Darwin; Peters, Thorsten; Bräuning, Achim</p> <p>2015-10-01</p> <p>This study investigates the dendroclimatic potential of tree species in a tropical dry forest in southern Ecuador. From 10 selected tree species, Bursera graveolens and Maclura tinctoria exhibited distinct annual and cross-datable tree-<span class="hlt">rings</span>. It was possible to synchronize individual tree-<span class="hlt">ring</span> series and to establish two tree-<span class="hlt">ring</span> chronologies of 203 and 87 years length, respectively. The characteristic ENSO frequency band is reflected in wavelet power spectra of both chronologies. Both species show a strong correlation between <span class="hlt">ring</span> <span class="hlt">width</span> and precipitation of the wet season (January-May). Strong El Niño events (1972, 1983 and 1998) lead to strong <span class="hlt">growth</span> responses in the tree-<span class="hlt">ring</span> chronologies, whereas 'normal' ENSO events do not trigger long-lasting <span class="hlt">growth</span> responses. The first <span class="hlt">ring-width</span> based wet-season precipitation reconstruction for the past 103 years was developed. Statistical and spatial correlation analysis verified the skills of the reconstructed precipitation which captures a great part of the Rainfall Index over the land area of Ecuador and the equatorial Pacific. Furthermore, teleconnections with central Pacific precipitation and SST patterns were found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ASPC..272..263G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ASPC..272..263G"><span id="translatedtitle">Planetary <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.</p> <p>2002-08-01</p> <p>The past two decades have witnessed dramatic changes in our view and understanding of planetary <span class="hlt">rings</span>. We now know that each of the giant planets in the Solar System possesses a complex and unique <span class="hlt">ring</span> system. Recent studies have identified complex gravitational interactions between the <span class="hlt">rings</span> and their retinues of attendant satellites. Among the four known <span class="hlt">ring</span> systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting <span class="hlt">ring</span> scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various <span class="hlt">ring</span> systems, in the broadest context. Understanding the origin and age requires us to know the current <span class="hlt">ring</span> properties, and to understand the dominant evolutionary processes and how they influence <span class="hlt">ring</span> properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary <span class="hlt">rings</span>. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary <span class="hlt">ring</span> science.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ClDy...44..791T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ClDy...44..791T&link_type=ABSTRACT"><span id="translatedtitle">Probabilistic reconstructions of local temperature and soil moisture from tree-<span class="hlt">ring</span> data with potentially time-varying climatic response</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tolwinski-Ward, S. E.; Tingley, M. P.; Evans, M. N.; Hughes, M. K.; Nychka, D. W.</p> <p>2015-02-01</p> <p>We explore a probabilistic, hierarchical Bayesian approach to the simultaneous reconstruction of local temperature and soil moisture from tree-<span class="hlt">ring</span> <span class="hlt">width</span> observations. The model explicitly allows for differing calibration and reconstruction interval responses of the <span class="hlt">ring-width</span> series to climate due to slow changes in climatology coupled with the biological climate thresholds underlying tree-<span class="hlt">ring</span> <span class="hlt">growth</span>. A numerical experiment performed using synthetically generated data demonstrates that bimodality can occur in posterior estimates of past climate when the data do not contain enough information to determine whether temperature or moisture limitation controlled reconstruction-interval tree-<span class="hlt">ring</span> variability. This manifestation of nonidentifiability is a result of the many-to-one mapping from bivariate climate to time series of tree-<span class="hlt">ring</span> <span class="hlt">widths</span>. The methodology is applied to reconstruct temperature and soil moisture conditions over the 1080-1129 C.E. interval at Methusalah Walk in the White Mountains of California, where co-located isotopic dendrochronologies suggest that observed moisture limitations on tree <span class="hlt">growth</span> may have been alleviated. Our model allows for assimilation of both data sources, and computation of the probability of a change in the climatic controls on <span class="hlt">ring-width</span> relative to those observed in the calibration period. While the probability of a change in control is sensitive to the choice of prior distribution, the inference that conditions were moist and cool at Methuselah Walk during the 1080-1129 C.E. interval is robust. Results also illustrate the power of combining multiple proxy data sets to reduce uncertainty in reconstructions of paleoclimate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26789943','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26789943"><span id="translatedtitle">Directed <span class="hlt">Growth</span> of Polymer Nanorods Using Surface-Initiated <span class="hlt">Ring</span>-Opening Polymerization of N-Allyl N-Carboxyanhydride.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Lu; Lahasky, Samuel H; Zhang, Donghui; Garno, Jayne C</p> <p>2016-02-17</p> <p>A stepwise chemistry route was used to prepare arrays of polymer nanostructures of poly(N-allyl glycine) on Si(111) using particle lithography. The nanostructures were used for studying surface reactions with advanced measurements of atomic force microscopy (AFM). In the first step to fabricate the surface platform, isolated nanopores were prepared within a thin film of octadecyltrichlorosilane (OTS). The OTS served as a surface resist, and the areas of nanopores provided multiple, regularly shaped sites for further reaction. An initiator, (3-aminopropyl)triethoxysilane (APTES), was grown selectively inside the nanopores to define sites for polymerization. The initiator attached selectively to the sites of nanopores indicating OTS prevented nonspecific adsorption. Surface-initiated <span class="hlt">ring</span>-opening polymerization of N-allyl N-carboxyanhydride with APTES produced polymer nanorods on the nanodots of APTES presenting amine functional groups. The surface changes for each step were monitored using high resolution atomic force microscopy (AFM). Slight variations in the height of the poly(N-allyl glycine) nanorods were observed which scale correspondingly to the initial dimensions of nanopores. The distance between adjacent polymer nanorods was controlled by the size of mesoparticle masks used in the experiment. This surface platform has potential application in biotechnology for smart coatings or biosensors. PMID:26789943</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013548','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013548"><span id="translatedtitle">Nuclear <span class="hlt">Rings</span> in Galaxies - A Kinematic Perspective</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mazzuca, Lisa M.; Swaters, Robert A.; Knapen, Johan H.; Veilleux, Sylvain</p> <p>2011-01-01</p> <p>We combine DensePak integral field unit and TAURUS Fabry-Perot observations of 13 nuclear <span class="hlt">rings</span> to show an interconnection between the kinematic properties of the <span class="hlt">rings</span> and their resonant origin. The nuclear <span class="hlt">rings</span> have regular and symmetric kinematics, and lack strong non-circular motions. This symmetry, coupled with a direct relationship between the position angles and ellipticities of the <span class="hlt">rings</span> and those of their host galaxies, indicate the <span class="hlt">rings</span> are in the same plane as the disc and are circular. From the rotation curves derived, we have estimated the compactness (v(sup 2)/r) up to the turnover radius, which is where the nuclear <span class="hlt">rings</span> reside. We find that there is evidence of a correlation between compactness and <span class="hlt">ring</span> <span class="hlt">width</span> and size. Radially wide <span class="hlt">rings</span> are less compact, and thus have lower mass concentration. The compactness increases as the <span class="hlt">ring</span> <span class="hlt">width</span> decreases. We also find that the nuclear <span class="hlt">ring</span> size is dependent on the bar strength, with weaker bars allowing <span class="hlt">rings</span> of any size to form.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Icar..226.1275S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Icar..226.1275S"><span id="translatedtitle">The vertical structure of the F <span class="hlt">ring</span> of Saturn from <span class="hlt">ring</span>-plane crossings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scharringhausen, Britt R.; Nicholson, Philip D.</p> <p>2013-11-01</p> <p>We present a photometric model of the <span class="hlt">rings</span> of Saturn which includes the main <span class="hlt">rings</span> and an F <span class="hlt">ring</span>, inclined to the main <span class="hlt">rings</span>, with a Gaussian vertical profile of optical depth. This model reproduces the asymmetry in brightness between the east and west ansae of the <span class="hlt">rings</span> of Saturn that was observed by the Hubble Space Telescope (HST) within a few hours after the Earth <span class="hlt">ring</span>-plane crossing (RPX) of 10 August 1995. The model shows that during this observation the inclined F <span class="hlt">ring</span> unevenly blocked the east and west ansae of the main <span class="hlt">rings</span>. The brightness asymmetry produced by the model is highly sensitive to the vertical thickness and radial optical depth of the F <span class="hlt">ring</span>. The F-<span class="hlt">ring</span> model that best matches the observations has a vertical full <span class="hlt">width</span> at half maximum of 13 ± 7 km and an equivalent depth of 10 ± 4 km. The model also reproduces the shape of the HST profiles of <span class="hlt">ring</span> brightness vs. distance from Saturn, both before and after the time of <span class="hlt">ring</span>-plane crossing. Smaller asymmetries observed before the RPX, when the Earth was on the dark side of the <span class="hlt">rings</span>, cannot be explained by blocking of the main <span class="hlt">rings</span> by the F <span class="hlt">ring</span> or vice versa and are probably instead due to the intrinsic longitudinal variation exhibited by the F <span class="hlt">ring</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020005141&hterms=Electromagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DElectromagnetism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020005141&hterms=Electromagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DElectromagnetism"><span id="translatedtitle">Planetary <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cuzzi, Jeffrey N.</p> <p>1994-01-01</p> <p>Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary <span class="hlt">ring</span> particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary <span class="hlt">rings</span>, and the fundamental questions were, why is Saturn the only planet with <span class="hlt">rings</span>, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary <span class="hlt">ring</span> systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise <span class="hlt">ring</span> systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that <span class="hlt">ring</span> systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary <span class="hlt">ring</span> systems, if not the <span class="hlt">ring</span> systems themselves, are considerably younger than the solar system</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26086094','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26086094"><span id="translatedtitle">Arabidopsis <span class="hlt">RING</span> E3 ubiquitin ligase AtATL80 is negatively involved in phosphate mobilization and cold stress response in sufficient phosphate <span class="hlt">growth</span> conditions.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suh, Ji Yeon; Kim, Woo Taek</p> <p>2015-08-01</p> <p>Phosphate (Pi) remobilization in plants is critical to continuous <span class="hlt">growth</span> and development. AtATL80 is a plasma membrane (PM)-localized <span class="hlt">RING</span> E3 ubiquitin (Ub) ligase that belongs to the Arabidopsis Tóxicos en Levadura (ATL) family. AtATL80 was upregulated by long-term low Pi (0-0.02 mM KH2PO4) conditions in Arabidopsis seedlings. AtATL80-overexpressing transgenic Arabidopsis plants (35S:AtATL80-sGFP) displayed increased phosphorus (P) accumulation in the shoots and lower biomass, as well as reduced P-utilization efficiency (PUE) under high Pi (1 mM KH2PO4) conditions compared to wild-type plants. The loss-of-function atatl80 mutant line exhibited opposite phenotypic traits. The atatl80 mutant line bolted earlier than wild-type plants, whereas AtATL80-overexpressors bloomed significantly later and produced lower seed yields than wild-type plants under high Pi conditions. Thus, AtATL80 is negatively correlated not only with P content and PUE, but also with biomass and seed yield in Arabidopsis. In addition, AtATL80-overexpressors were significantly more sensitive to cold stress than wild-type plants, while the atatl80 mutant line exhibited an increased tolerance to cold stress. Taken together, our results suggest that AtATL80, a PM-localized ATL-type <span class="hlt">RING</span> E3 Ub ligase, participates in the Pi mobilization and cold stress response as a negative factor in Arabidopsis. PMID:26086094</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1812343Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1812343Z&link_type=ABSTRACT"><span id="translatedtitle">Challenges in Establishing Multi-Millennial Tree <span class="hlt">Ring</span> Records for the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ziehmer, Malin Michelle; Nicolussi, Kurt; Schlüchter, Christian; Leuenberger, Markus</p> <p>2016-04-01</p> <p>Recent finds of wood remains from glacier forefields and peat bogs along a SW-NE transect in the Alps represent a unique high-frequency archive which allows the reconstruction of climate variability over the entire Holocene. We use a multi-proxy approach that combines both tree <span class="hlt">ring</span> <span class="hlt">width</span> and multiple stable isotope chronologies by establishing highly resolved tree <span class="hlt">ring</span> and stable isotope records from calendar-dated wood covering the past 9000 years. Therefore, tree <span class="hlt">ring</span> <span class="hlt">width</span> and stable isotope series are generated by a standardized procedure, where first the tree <span class="hlt">ring</span> <span class="hlt">widths</span> are measured and samples are calendrically dated by means of tree <span class="hlt">ring</span> analysis. Afterwards, samples are cut into 5-year tree <span class="hlt">ring</span> blocks, cellulose is extracted and crushed by ultrasonic homogenization, and subsequently, the stable isotopes of carbon, oxygen and hydrogen are simultaneously measured. Although the sample preparation follows a standardized procedure, the establishment of the multi-millennial tree <span class="hlt">ring</span> and isotope chronologies is not straightforward. By investigating the individual measurement series from the Early and Mid-Holocene as well as recent samples from living trees from key sites - which will provide the connection of the Holocene tree <span class="hlt">ring</span> series to the present - the individual measurement series reveal effects due to different sampling sites, tree species, <span class="hlt">growth</span> trend, potential degree of decay and cellulose content. These specific effects influence both the tree <span class="hlt">ring</span> <span class="hlt">width</span>, and to a higher degree the stable isotope series. For instance, the measured deuterium records reveal a species-specific isotope signature for the investigated species Larix decidua and Pinus cembra, which is not resembled in the oxygen and carbon records. In order to establish stable isotope chronologies which span the time period from 9000 years b2k to the present, such tree specific features need to be corrected from the individual time series. In this study, we try to overcome these various</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JHEP...03..214S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JHEP...03..214S"><span id="translatedtitle">On the maximal diphoton <span class="hlt">width</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salvio, Alberto; Staub, Florian; Strumia, Alessandro; Urbano, Alfredo</p> <p>2016-03-01</p> <p>Motivated by the 750 GeV diphoton excess found at LHC, we compute the maximal <span class="hlt">width</span> into γγ that a neutral scalar can acquire through a loop of charged fermions or scalars as function of the maximal scale at which the theory holds, taking into account vacuum (meta)stability bounds. We show how an extra gauge symmetry can qualitatively weaken such bounds, and explore collider probes and connections with Dark Matter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25345032','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25345032"><span id="translatedtitle">[Dendroclimatic potentials for the tree <span class="hlt">rings</span> of Huangshan pine (Pinus taiwanensis ) at Xiaolinhai in the western Dabie Mountains, China].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peng, Jian-Feng; Li, Guo-Dong; Li, Ling-Ling</p> <p>2014-07-01</p> <p>By using the dendrochronology research methods, this paper developed the 1915-2011 tree <span class="hlt">ring-width</span> standard chronology of the Huangshan pine (Pinus taiwanesis) at the north slope of western Dabie Mountains in the junction of Hubei, Henan and Anhui provinces. High mean sensitivity (MS) indicated that there was conspicuous high-frequency climate signals and high first-order autocorrelation (AC) showed there were significant lag-effects of tree previous <span class="hlt">growth</span>. The higher signal-to-noise ratio (SNR) and expressed population signal (EPS) indicated that the trees had high levels of common climate signals. Correlations between the tree <span class="hlt">ring-width</span> standard chronology and climatic factors (1959-2011) revealed the significant influences of temperature, precipitation and relative humidity on the tree <span class="hlt">width</span> <span class="hlt">growth</span> of Huangshan pine by the end of growing season (September and October). Significant positive correlations were found between the tree-<span class="hlt">ring</span> indices and the Palmer drought severity index (PDSI) of current September and October. In conclusion, the combination of water and heat of September and October is the major effect factor for the <span class="hlt">growth</span> of Huangshan pine in western Dabie Mountains. PMID:25345032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27573111','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27573111"><span id="translatedtitle">Wall proficient E. coli capable of sustained <span class="hlt">growth</span> in the absence of the Z-<span class="hlt">ring</span> division machine.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mercier, Romain; Kawai, Yoshikazu; Errington, Jeff</p> <p>2016-01-01</p> <p>The peptidoglycan cell wall is a major protective external sheath in bacteria and a key target for antibiotics(1). Peptidoglycan is present in virtually all bacteria, suggesting that it was probably present in the last bacterial common ancestor(2). Cell wall expansion is orchestrated by cytoskeletal proteins related to actin (MreB) and tubulin (FtsZ)(3). FtsZ is a key essential player in a highly organized division machine that directs an invaginating annulus of cell wall peptidoglycan. The recent discovery that cell-wall-less bacteria (L-forms) can grow and divide independently of FtsZ(4,5), provided a means of generating an ftsZ null mutant of Escherichia coli. Remarkably, we have been able to isolate variants of E. coli that lack FtsZ but are capable of efficient <span class="hlt">growth</span> in a walled state. Genetic analysis reveals that a combination of mutations is needed for this phenotype. Importantly, the suppressive mutations lead to a major cell shape change, from the normal cylindrical shape to a branched and bulging, ramified shape, which we call 'coli-flower'. The results highlight the versatility of bacterial cells and illustrate possible evolutionary routes leading to the emergence of specialized bacteria, such as pathogenic Chlamydia or aquatic Planctomycetes, that lack FtsZ but retain the cell wall(6-8). PMID:27573111</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EPSC....9..633S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EPSC....9..633S&link_type=ABSTRACT"><span id="translatedtitle">Propellers in Saturn's <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.</p> <p>2014-04-01</p> <p> detection in UVIS β Centauri Rev96 occultation at r=94,958km offers insight into the morphology of the discovered objects in B <span class="hlt">ring</span>. The feature is statistically significant, consists of 6 consequent high counts, and represents a gap with a <span class="hlt">width</span> of 300m. Similar to the Bleriot occultation in Persei Rev42, the B <span class="hlt">ring</span> β Centauri occultation also shows a very prominent gap and a single flanking higher density wake. The significance of the UVIS features was confirmed using statistical T-test. The result from UVIS occultation together with dozen feature detections in ISS NAC images demonstrates beyond reasonable doubt that the presented B <span class="hlt">ring</span> features are indeed propellers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.1427K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.1427K"><span id="translatedtitle">Climatic variations on longest tree-<span class="hlt">ring</span> chronologies for Kola Peninsula and Finnish Lapland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kasatkina, E. A.; Shumilov, O. I.; Timonen, M.; Mielikainen, K.; Helama, S.; Kanatjev, A. G.; Kirtsideli, I. Yu.</p> <p>2010-05-01</p> <p>We investigated the external factor (solar activity, volcanic eruptions) influence on tree <span class="hlt">growth</span> at high latitudes. We analysed a 561-year tree-<span class="hlt">ring</span> record of pine (Pinus sylvestris L.) and a 676-year juniper (Juniperus Sibirica Burgst.) tree-<span class="hlt">ring</span> chronology collected nearby the northern timberline (67.77-68.63N; 33.25-36.52 E) at the Kola Peninsula, northwestern Russia. As well known the climatic impacts of solar and volcanic activity vary regionally, and major volcanic eruptions do not always result in regional cooling. A response of tree <span class="hlt">growth</span> at the Kola Peninsula to climatic changes due to solar variability and volcanic eruptions was revealed. For example, Dalton minimum of solar activity (1801-1816 AD) and Laki (1783 AD) and Tambora (1815 AD) volcanic eruptions appeared to cause the greatest <span class="hlt">ring-width</span> reduction and cooling. The minima of solar activity Sporer (1416-1534 AD) and Maunder (1645-1715 AD) were as well accompanied by temperature decreases. Intervals with an absence of significant volcanic eruptions correspond to intervals of increased <span class="hlt">ring-width</span> values. A superposed epoch analysis of 19 large (Volcanic Explosivity Index, VEI>5) volcanic events revealed a significant suppression of tree <span class="hlt">growth</span> for up to 8 years following volcanic eruptions. The similar effect (supression of tree <span class="hlt">growth</span> after powerful volcanic eruptions) was obtained under analysis of the 7641-year supra-long pine tree-<span class="hlt">ring</span> chronology for Finnish Lapland. Our results documenting the regional climatic impacts of solar and volcanic activity permit us to understand the dynamics of the climate system and its response to external forcing. This work is financially supported by grant from Russian Foundation for Basic Research (grant No. 09-04-98801), by the Program of the Russian Academy and by the Regional Scientific Program of Murmansk region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27301603','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27301603"><span id="translatedtitle">Vascular <span class="hlt">rings</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K</p> <p>2016-06-01</p> <p>The term vascular <span class="hlt">ring</span> refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular <span class="hlt">rings</span> are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular <span class="hlt">ring</span> is best established by CT imaging that can accurately delineate the anatomy of the vascular <span class="hlt">ring</span> and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular <span class="hlt">ring</span> is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular <span class="hlt">rings</span> should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. PMID:27301603</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7195646','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7195646"><span id="translatedtitle">Possible bias in tree-<span class="hlt">ring</span> time series due to mortality</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lucier, A A; Warnick, W L; Hyink, D M</p> <p>1989-07-01</p> <p>This article discusses the possible bias in tree-<span class="hlt">ring</span> time series studies extending from the year of sample collection to a prepollution period. The authors hypothesizes that normal mortality (i.e., mortality not associated with sudden disturbance) can cause reduced tree <span class="hlt">ring</span> <span class="hlt">widths</span> in years preceding actual tree death and produce a bias toward smaller and more variable <span class="hlt">ring</span> <span class="hlt">widths</span> at the end of the tree-<span class="hlt">ring</span> time series.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.2871W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.2871W"><span id="translatedtitle">From process to proxy: Ecological challenges and opportunities of tree-<span class="hlt">ring</span> based environmental reconstructions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilmking, Martin; Buras, Allan; Heinrich, Ingo; Scharnweber, Tobias; Simard, Sonia; Smiljanic, Marko; van der Maaten, Ernst; van der Maaten-Theunissen, Marieke</p> <p>2014-05-01</p> <p>Trees are sessile, long-living organisms and as such constantly need to adapt to changing environmental conditions. Accordingly, they often show high phenotypic plasticity (the ability to change phenotypic traits, such as allocation of resources) in response to environmental change. This high phenotypic plasticity is generally considered as one of the main ingredients for a sessile organism to survive and reach high ages. Precisely because of the ability of trees to reach old age and their in-ability to simply run away when conditions get worse, <span class="hlt">growth</span> information recorded in tree <span class="hlt">rings</span> has long been used as a major environmental proxy, covering time scales from decades to millennia. Past environmental conditions (e.g. climate) are recorded in i.e. annual tree-<span class="hlt">ring</span> <span class="hlt">width</span>, early- and latewood <span class="hlt">width</span>, wood density, isotopic concentrations, cell anatomy or wood chemistry. One prerequisite for a reconstruction is that the relationship between the environmental variable influencing tree <span class="hlt">growth</span> and the tree-<span class="hlt">growth</span> variable itself is stable through time. This, however, might contrast the ecological theory of high plasticity and the trees ability to adapt to change. To untangle possible mechanisms leading to stable or unstable relationships between tree <span class="hlt">growth</span> and environmental variables, it is helpful to have exact site information and several proxy variables of each tree-<span class="hlt">ring</span> series available. Although we gain insight into the environmental history of a sampling site when sampling today, this is extremely difficult when using archeological wood. In this latter case, we face the additional challenge of unknown origin, provenance and (or) site conditions, making it even more important to use multiple proxy time-series from the same sample. Here, we review typical examples, where the relationship between tree <span class="hlt">growth</span> and environmental variables seems 1) stable and 2) instable through time, and relate these two cases to ecological theory. Based on ecological theory, we then</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/988765','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/988765"><span id="translatedtitle">Storage <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fischer, W.</p> <p>2011-01-01</p> <p>Storage <span class="hlt">rings</span> are circular machines that store particle beams at a constant energy. Beams are stored in <span class="hlt">rings</span> without acceleration for a number of reasons (Tab. 1). Storage <span class="hlt">rings</span> are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage <span class="hlt">rings</span> such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage <span class="hlt">ring</span> but may not be extracted (Fig. 1). Accelerator <span class="hlt">rings</span> such as synchrotrons are used as storage <span class="hlt">rings</span> before and after acceleration. Particles stored in <span class="hlt">rings</span> include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in <span class="hlt">rings</span> requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage <span class="hlt">rings</span>. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820033629&hterms=occult&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doccult','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820033629&hterms=occult&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Doccult"><span id="translatedtitle">No evidence of <span class="hlt">rings</span> around Neptune</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elliot, J. L.; Mink, D. J.; Baron, R. L.; Dunham, E.; Pingree, J. E.; French, R. G.; Elias, J. H.; Liller, W.; Nicholson, P. D.; Jones, T. J.</p> <p>1981-01-01</p> <p>The results of two observations of stellar occultations of Neptune to determine if the planet has a <span class="hlt">ring</span> system are reported. The sightings were made from Mt. Stromlo, Mauna Kea, and Cerro Tololo, noting that an equatorial <span class="hlt">ring</span> would subtend only two arcsec of view. An upper accretion limit was defined to set the region around Neptune where <span class="hlt">rings</span>, rather than satellites, could form. The intensities of the starlight from the two selected stars were recorded by photometers on magnetic tape during the occultation period. One of the stars did not occult, but passed through the entire region where a <span class="hlt">ring</span> system might be present. No definitive evidence for <span class="hlt">rings</span> was found, although an optical depth for a Neptunian <span class="hlt">ring</span> was calculated at 0.07, with a <span class="hlt">width</span> of more than 5 km and a radius of 31,400 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol3/pdf/CFR-2012-title14-vol3-sec121-95.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol3/pdf/CFR-2012-title14-vol3-sec121-95.pdf"><span id="translatedtitle">14 CFR 121.95 - Route <span class="hlt">width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route <span class="hlt">width</span>... routes in the case of certificate holders conducting flag operations) have a <span class="hlt">width</span> equal to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GPC...122..140C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GPC...122..140C"><span id="translatedtitle">A cluster of stratospheric volcanic eruptions in the AD 530s recorded in Siberian tree <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Churakova (Sidorova), Olga V.; Bryukhanova, Marina V.; Saurer, Matthias; Boettger, Tatjana; Naurzbaev, Mukhtar M.; Myglan, Vladimir S.; Vaganov, Eugene A.; Hughes, Malcolm K.; Siegwolf, Rolf T. W.</p> <p>2014-11-01</p> <p>Recently published, improved chronologies for volcanic sulfate in Greenland and Antarctic ice permit a comparison of the <span class="hlt">growth</span> responses of absolutely annually dated tree <span class="hlt">rings</span> at three locations in Siberia with annual ice-core records of volcanic eruptions centered on AD 536. For the first time for this region and period, we present unique data sets for tree-<span class="hlt">ring</span> <span class="hlt">width</span>, cell-wall thickness, δ13C and δ18O in cellulose. These were based on multiple samples from relict wood of larch obtained from two sites close to the northern limit of tree <span class="hlt">growth</span> on the Taimyr Peninsula and in northeastern Yakutia, and at a high-elevation, location 20° further South in the Altai Mts. An event in AD 536 was associated with different, but marked, changes in tree-<span class="hlt">ring</span> parameters at the high-latitude sites compared with the high elevation site. An AD 541 event was associated with its own distinctive tree-<span class="hlt">ring</span> responses across the three sites and multiple variables. The years after AD 532 were marked by a strong and sustained decrease in <span class="hlt">growth</span> at the high-elevation, more southerly, site. The combination of improved ice-core chronology for the climatically effective volcanic eruptions of this part of the 6th century AD, and an array of tree-<span class="hlt">ring</span> sites with different climates and multiple tree-<span class="hlt">ring</span> variables permits a richer description of tree responses to this cluster of events. The pattern of tree-<span class="hlt">ring</span> parameter responses at the three locations in AD 536, AD 541, and perhaps AD 532 is consistent with responses to climatically effective volcanic eruptions influencing tree response in those and subsequent years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980Msngr..21...29D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980Msngr..21...29D"><span id="translatedtitle"><span class="hlt">Ring</span> Galaxies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dennefeld, M.; Materne, J.</p> <p>1980-09-01</p> <p>Among the 338 exotic, intriguing and/or fascinating objects contained in Arp's catalogue of peculiar galaxies, two, Arp 146 and 147, are calling special attention as a presumably separate class of objects displaying closed <span class="hlt">rings</span> with almost empty interior. It is difficult to find out when, historically speaking, attention was called first to this type of object as a peculiar class, but certainly ga1axies with <span class="hlt">rings</span> were widely found and recognized in the early sixties, ul}der others by Vorontsov-Velyaminov (1960), Sandage (1961) in the Hubble Atlas or de Vaucouleurs (1964) in the first reference catalogue of ga1axies. The most recent estimates by Arp and Madore (1977) from a search on about 200 Schmidt plates covering 7,000 square degrees give 3.6 per cent of <span class="hlt">ring</span> galaxies among 2,784 peculiar galaxies found. However, despite the mythological perfection associated with a circle, some ordering is necessary before trying to understand the nature of such objects. This is particularly true because a large fraction of those galaxies with <span class="hlt">rings</span> are probably normal spiral galaxies of type RS or S(r) as defined by de Vaucouleurs, where the spiral arms are simply "closing the circle". A good example of such "ordinary" galaxy is NGC 3081 in the Hubble Atlas .</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title23-vol1/pdf/CFR-2014-title23-vol1-sec658-15.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title23-vol1/pdf/CFR-2014-title23-vol1-sec658-15.pdf"><span id="translatedtitle">23 CFR 658.15 - <span class="hlt">Width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-04-01</p> <p>... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, <span class="hlt">WIDTH</span> AND WEIGHT LIMITATIONS § 658.15 <span class="hlt">Width</span>. (a) No State shall impose a <span class="hlt">width</span> limitation of more or less than 102 inches, or its approximate metric equivalent, 2.6 meters (102.36 inches)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title23-vol1/pdf/CFR-2011-title23-vol1-sec658-15.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title23-vol1/pdf/CFR-2011-title23-vol1-sec658-15.pdf"><span id="translatedtitle">23 CFR 658.15 - <span class="hlt">Width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, <span class="hlt">WIDTH</span> AND WEIGHT LIMITATIONS § 658.15 <span class="hlt">Width</span>. (a) No State shall impose a <span class="hlt">width</span> limitation of more or less than 102 inches, or its approximate metric equivalent, 2.6 meters (102.36 inches)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title23-vol1/pdf/CFR-2012-title23-vol1-sec658-15.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title23-vol1/pdf/CFR-2012-title23-vol1-sec658-15.pdf"><span id="translatedtitle">23 CFR 658.15 - <span class="hlt">Width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-04-01</p> <p>... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, <span class="hlt">WIDTH</span> AND WEIGHT LIMITATIONS § 658.15 <span class="hlt">Width</span>. (a) No State shall impose a <span class="hlt">width</span> limitation of more or less than 102 inches, or its approximate metric equivalent, 2.6 meters (102.36 inches)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title23-vol1/pdf/CFR-2013-title23-vol1-sec658-15.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title23-vol1/pdf/CFR-2013-title23-vol1-sec658-15.pdf"><span id="translatedtitle">23 CFR 658.15 - <span class="hlt">Width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-04-01</p> <p>... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, <span class="hlt">WIDTH</span> AND WEIGHT LIMITATIONS § 658.15 <span class="hlt">Width</span>. (a) No State shall impose a <span class="hlt">width</span> limitation of more or less than 102 inches, or its approximate metric equivalent, 2.6 meters (102.36 inches)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title23-vol1/pdf/CFR-2010-title23-vol1-sec658-15.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title23-vol1/pdf/CFR-2010-title23-vol1-sec658-15.pdf"><span id="translatedtitle">23 CFR 658.15 - <span class="hlt">Width</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, <span class="hlt">WIDTH</span> AND WEIGHT LIMITATIONS § 658.15 <span class="hlt">Width</span>. (a) No State shall impose a <span class="hlt">width</span> limitation of more or less than 102 inches, or its approximate metric equivalent, 2.6 meters (102.36 inches)...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26142450','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26142450"><span id="translatedtitle">Functional adjustments of xylem anatomy to climatic variability: insights from long-term Ilex aquifolium tree-<span class="hlt">ring</span> series.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rita, Angelo; Cherubini, Paolo; Leonardi, Stefano; Todaro, Luigi; Borghetti, Marco</p> <p>2015-08-01</p> <p>The present study assessed the effects of climatic conditions on radial <span class="hlt">growth</span> and functional anatomical traits, including <span class="hlt">ring</span> <span class="hlt">width</span>, vessel size, vessel frequency and derived variables, i.e., potential hydraulic conductivity and xylem vulnerability to cavitation in Ilex aquifolium L. trees using long-term tree-<span class="hlt">ring</span> time series obtained at two climatically contrasting sites, one mesic site in Switzerland (CH) and one drought-prone site in Italy (ITA). Relationships were explored by examining different xylem traits, and point pattern analysis was applied to investigate vessel clustering. We also used generalized additive models and bootstrap correlation functions to describe temperature and precipitation effects. Results indicated modified radial <span class="hlt">growth</span> and xylem anatomy in trees over the last century; in particular, vessel frequency increased markedly at both sites in recent years, and all xylem traits examined, with the exception of xylem cavitation vulnerability, were higher at the CH mesic compared with the ITA drought site. A significant vessel clustering was observed at the ITA site, which could contribute to an enhanced tolerance to drought-induced embolism. Flat and negative relationships between vessel size and <span class="hlt">ring</span> <span class="hlt">width</span> were observed, suggesting carbon was not allocated to radial <span class="hlt">growth</span> under conditions which favored stem water conduction. Finally, in most cases results indicated that climatic conditions influenced functional anatomical traits more substantially than tree radial <span class="hlt">growth</span>, suggesting a crucial role of functional xylem anatomy in plant acclimation to future climatic conditions. PMID:26142450</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992ClDy....6..161H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992ClDy....6..161H"><span id="translatedtitle">Drought frequency in central California since 101 B.C. recorded in giant sequoia tree <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, Malcolm K.; Brown, Peter M.</p> <p>1992-01-01</p> <p>Well replicated tree-<span class="hlt">ring</span> <span class="hlt">width</span> index chronologies have been developed for giant sequoia at three sites in the Sierra Nevada, California. Extreme low-<span class="hlt">growth</span> events in these chronologies correspond with regional drought events in the twentieth century in the San Joaquin drainage, in which the giant sequoia sites are located. This relationship is based upon comparison of tree-<span class="hlt">ring</span> indices with August Palmer Drought Severity Indices for California Climate Division 5. <span class="hlt">Ring-width</span> indices in the lowest decile from each site were compared. The frequency of low-<span class="hlt">growth</span> events which occurred at all three sites in the same year is reconstructed from 101 B.C. to A.D. 1988. The inferred frequency of severe drought events changes through time, sometimes suddenly. The period from roughly 1850 to 1950 had one of the lowest frequencies of drought of any one hundred year period in the 2089 year record. The twentieth century so far has had a below-average frequency of extreme droughts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/181935','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/181935"><span id="translatedtitle">Drought frequency in central California since 101 B.C. recordered in giant sequoia tree <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hughes, M.K.; Brown, P.M.</p> <p>1992-01-01</p> <p>Well replicated tree-<span class="hlt">ring</span> <span class="hlt">width</span> index chronologies have been developed for giant sequoia at three sites in the Sierra Nevada, California. Extreme low-<span class="hlt">growth</span> events in these chronologies correspond with regional drought events in the twentieth century in the San Joaquin drainage, in which the giant sequoia sites are located. This relationship is based upon comparison of tree-<span class="hlt">ring</span> indices with August Palmer Drought Severity Indices for California Climate Division 5. <span class="hlt">Ring-width</span> indices in the lowest decile from each site were compared. The frequency of low-<span class="hlt">growth</span> events which occurred at all three sites in the same year is reconstructed from 101 B.C. to A.D. 1988. The inferred frequency of severe drought events changes through time, sometimes suddenly. The period from roughly 1850 to 1950 had one of the lowest frequencies of drought of any one hundred year period in the 2089 year record. The twentieth century so far has had a below-average frequency of extreme droughts. 26 refs., 6 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/960972','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/960972"><span id="translatedtitle">Fjords in viscous fingering: selection of <span class="hlt">width</span> and opening scale</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mineev-weinstein, Mark; Ristroph, Leif; Thrasher, Matthew; Swinney, Harry</p> <p>2008-01-01</p> <p>Our experiments on viscous fingering of air into oil contained between closely spaced plates reveal two selection rules for the fjords of oil that separate fingers of air. (Fjords are the building blocks of solutions of the zero-surface-tension Laplacian <span class="hlt">growth</span> equation.) Experiments in rectangular and circular geometries yield fjords with base <span class="hlt">widths</span> {lambda}{sub c}/2, where {lambda}{sub c} is the most unstable wavelength from a linear stability analysis. Further, fjords open at an angle of 8.0{sup o}{+-}1.0{sup o}. These selection rules hold for a wide range of pumping rates and fjord lengths, <span class="hlt">widths</span>, and directions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.B11A1009W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.B11A1009W"><span id="translatedtitle">Fog and Vegetation on the California Channel Islands: A Tree <span class="hlt">Ring</span> and Satellite Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, P.; Still, C.; Fischer, D.; Leavitt, S.</p> <p>2005-12-01</p> <p>Tree-<span class="hlt">ring</span> <span class="hlt">width</span> and stable isotope composition of rare pines in Channel Islands National Park reflect annual variations in water availability. α-cellulose was isolated from Bishop Pine ( Pinus muricata) cores from Santa Cruz Island (SCI). Individual annual <span class="hlt">rings</span> from 1979-2003 were analyzed for carbon-13 (n = 4 trees). An average δ13C chronology was created and annual atmospheric 13CO2 at La Jolla Pier, CA was subtracted to detrend the chronology for the steadily decreasing δ13C of atmospheric CO2 that has resulted from anthropogenic emissions and biomass burning. Early and latewood δ13C were negatively correlated with annual rainfall in the SCI central valley (r = -0.5057, r = -0.6447, respectively). An annual <span class="hlt">ring</span> <span class="hlt">width</span> chronology (1908-2004) was also created from Torrey Pine ( Pinus torreyana) tree cores (n=17) collected on Santa Rosa Island. <span class="hlt">Ring</span> <span class="hlt">width</span> was positively correlated with SCI rainfall (r = 0.6993). On average, 87% of this precipitation falls between November and March. However, tree <span class="hlt">growth</span> as measured by dendrometer bands continues throughout the summer months suggesting an additional source of water. Summer is also the peak fog season for the Islands. The last rain of the 2004 growing season was on March 1 and monthly NDVI data derived from MODIS show that the vast majority of the vegetation on SCI was dormant by mid-May. When summer NDVI is overlaid on an image of average summer-time 10:30AM cloud cover, created using a derivative of the MODIS cloud-mask product, it appears that the greenest parts of SCI during summer months are those regions that experience the most summertime cloud cover. The distribution of Bishop Pine also seems to be limited to elevations that intercept cloud banks, as opposed to regions that simply experience cloud cover. It is therefore possible that these tree <span class="hlt">ring</span> <span class="hlt">width</span> and stable isotope records document the intensity of summer fog inundation in addition to rainfall. Because we have observed consistently significant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP43B1486S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP43B1486S"><span id="translatedtitle">Projecting Future Water Availability in the Great Lakes Megalopolis: Reconstructing Lake Michigan-Huron Lake Level and Regional Hydroclimate Using Tree <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, K. R.</p> <p>2014-12-01</p> <p>The ability to accurately predict water availability in the cities surrounding Lake Michigan-Huron becomes particularly difficult when the uncertain effects of climate change, such as changes in precipitation patterns and evaporation rates, are considered. Lake level reconstructions provide useful model inputs to better predict this availability. Annual tree-<span class="hlt">ring</span> <span class="hlt">widths</span> have been successfully utilized in reconstructions of lake levels in the Great Lakes region via the creation of proxy datasets of temperature and precipitation that are then input into a multilinear regression model to reconstruct annual average lake level. Here, the combination of this approach with analysis of instrumental records of precipitation and stream flow input allows for a more comprehensive understanding of regional hydroclimate and improved projection of future water resource availability. Annual tree-<span class="hlt">ring</span> <span class="hlt">widths</span> of cores collected from four old-<span class="hlt">growth</span> forests near southern Lake Michigan were combined with over 30 archived tree-<span class="hlt">ring</span> <span class="hlt">width</span> chronologies from the Great Lakes region and used to create proxy datasets of temperature and precipitation. A multilinear regression model related these proxy variables to Lake Michigan-Huron lake level and stream flow of the Saint Clair River, which flows into Lake Michigan-Huron, for the period of available instrumental record (1860-present). When possible, the available tree-<span class="hlt">ring</span> <span class="hlt">widths</span> were used to reconstruct these variables for years prior to the instrumental record. Timing and severity of rainfall events were also analyzed to identify spatial and temporal patterns and their variability over time. The combination of updated tree-<span class="hlt">ring</span> <span class="hlt">width</span> chronologies, chronologies from newly sampled sites, and instrumental records of various indicators of water availability provides novel and valuable insight into the future lake level of Lake Michigan-Huron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGC24B..03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGC24B..03T"><span id="translatedtitle">Stable carbon isotopes and drought signal in the tree-<span class="hlt">rings</span> of northern white-cedar trees from boreal central Canada. (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tardif, J. C.; Au, R.</p> <p>2010-12-01</p> <p> both radial <span class="hlt">growth</span> and carbon assimilation, particularly during the month of June in the current growing season. During this month, the <span class="hlt">ring-width</span> index was sensitive to moisture stress (positive and negative association with precipitation and temperature, respectively) whereas the δ13C index showed enrichment with increasing temperature and drought index. Our results also suggested that in T. occidentalis <span class="hlt">ring</span> <span class="hlt">width</span> was more responsive to prolonged drought than δ13C since periods of decreased radial <span class="hlt">growth</span> most often coincided with documented drought intervals. Past experimental studies had indicated that young T. occidentalis trees may adjust stomatal conductance following exposure to water deficit suggesting that trees could develop a tolerance to subsequent water deficit. We speculate that in periods of extended drought, the absence of sustained year-to-year enriched δ13C values in T. occidentalis trees may thus reflect stomatal conditioning. This suggests that tree-<span class="hlt">ring</span> δ13C in T. occidentalis trees may have limited utility in drought reconstruction. Comparing the T. occidentalis δ13C data with that of other coniferous species from northern Manitoba revealed that T. occidentalis was the most δ13C-enriched species and that it portrayed the lowest δ13C sensitivity. Low correlations also were observed between species chronologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26960389','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26960389"><span id="translatedtitle">Tree-<span class="hlt">ring</span> δ13C and δ18O, leaf δ13C and wood and leaf N status demonstrate tree <span class="hlt">growth</span> strategies and predict susceptibility to disturbance.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Billings, S A; Boone, A S; Stephen, F M</p> <p>2016-05-01</p> <p>Understanding how tree <span class="hlt">growth</span> strategies may influence tree susceptibility to disturbance is an important goal, especially given projected increases in diverse ecological disturbances this century. We use <span class="hlt">growth</span> responses of tree <span class="hlt">rings</span> to climate, relationships between tree-<span class="hlt">ring</span> stable isotopic signatures of carbon (δ(13)C) and oxygen (δ(18)O), wood nitrogen concentration [N], and contemporary leaf [N] and δ(13)C values to assess potential historic drivers of tree photosynthesis in dying and apparently healthy co-occurring northern red oak (Quercus rubra L. (Fagaceae)) during a region-wide oak decline event in Arkansas, USA. Bole <span class="hlt">growth</span> of both healthy and dying trees responded negatively to drought severity (Palmer Drought Severity Index) and temperature; healthy trees exhibited a positive, but small, response to growing season precipitation. Contrary to expectations, tree-<span class="hlt">ring</span> δ(13)C did not increase with drought severity. A significantly positive relationship between tree-<span class="hlt">ring</span> δ(13)C and δ(18)O was evident in dying trees (P < 0.05) but not in healthy trees. Healthy trees' wood exhibited lower [N] than that of dying trees throughout most of their lives (P < 0.05), and we observed a significant, positive relationship (P < 0.05) in healthy trees between contemporary leaf δ(13)C and leaf N (by mass), but not in dying trees. Our work provides evidence that for plants in which strong relationships between δ(13)C and δ(18)O are not evident, δ(13)C may be governed by plant N status. The data further imply that historic photosynthesis in healthy trees was linked to N status and, perhaps, C sink strength to a greater extent than in dying trees, in which tree-<span class="hlt">ring</span> stable isotopes suggest that historic photosynthesis was governed primarily by stomatal regulation. This, in turn, suggests that assessing the relative dominance of photosynthetic capacity vs stomatal regulation as drivers of trees' C accrual may be a feasible means of predicting tree</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27508933','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27508933"><span id="translatedtitle">Climate Response of Tree Radial <span class="hlt">Growth</span> at Different Timescales in the Qinling Mountains.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Changfeng; Liu, Yu</p> <p>2016-01-01</p> <p>The analysis of the tree radial <span class="hlt">growth</span> response to climate is crucial for dendroclimatological research. However, the response relationships between tree-<span class="hlt">ring</span> indices and climatic factors at different timescales are not yet clear. In this study, the tree-<span class="hlt">ring</span> <span class="hlt">width</span> of Huashan pine (Pinus armandii) from Huashan in the Qinling Mountains, north-central China, was used to explore the response differences of tree <span class="hlt">growth</span> to climatic factors at daily, pentad (5 days), dekad (10 days) and monthly timescales. Correlation function and linear regression analysis were applied in this paper. The tree-<span class="hlt">ring</span> <span class="hlt">width</span> showed a more sensitive response to daily and pentad climatic factors. With the timescale decreasing, the absolute value of the maximum correlation coefficient between the tree-<span class="hlt">ring</span> data and precipitation increases as well as temperature (mean, minimum and maximum temperature). Compared to the other three timescales, pentad was more suitable for analysing the response of tree <span class="hlt">growth</span> to climate. Relative to the monthly climate data, the association between the tree-<span class="hlt">ring</span> data and the pentad climate data was more remarkable and accurate, and the reconstruction function based on the pentad climate was also more reliable and stable. We found that the major climatic factor limiting Huashan pine <span class="hlt">growth</span> was the precipitation of pentads 20-35 (from April 6 to June 24) rather than the well-known April-June precipitation. The pentad was also proved to be a better timescale for analysing the climate and tree <span class="hlt">growth</span> in the western and eastern Qinling Mountains. The formation of the earlywood density of Chinese pine (Pinus tabulaeformis) from Shimenshan in western Qinling was mainly affected by the maximum temperature of pentads 28-32 (from May 16 to June 9). The maximum temperature of pentads 28-33 (from May 16 to June 14) was the major factor affecting the <span class="hlt">ring</span> <span class="hlt">width</span> of Chinese pine from Shirenshan in eastern Qinling. PMID:27508933</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4980003','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4980003"><span id="translatedtitle">Climate Response of Tree Radial <span class="hlt">Growth</span> at Different Timescales in the Qinling Mountains</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sun, Changfeng; Liu, Yu</p> <p>2016-01-01</p> <p>The analysis of the tree radial <span class="hlt">growth</span> response to climate is crucial for dendroclimatological research. However, the response relationships between tree-<span class="hlt">ring</span> indices and climatic factors at different timescales are not yet clear. In this study, the tree-<span class="hlt">ring</span> <span class="hlt">width</span> of Huashan pine (Pinus armandii) from Huashan in the Qinling Mountains, north-central China, was used to explore the response differences of tree <span class="hlt">growth</span> to climatic factors at daily, pentad (5 days), dekad (10 days) and monthly timescales. Correlation function and linear regression analysis were applied in this paper. The tree-<span class="hlt">ring</span> <span class="hlt">width</span> showed a more sensitive response to daily and pentad climatic factors. With the timescale decreasing, the absolute value of the maximum correlation coefficient between the tree-<span class="hlt">ring</span> data and precipitation increases as well as temperature (mean, minimum and maximum temperature). Compared to the other three timescales, pentad was more suitable for analysing the response of tree <span class="hlt">growth</span> to climate. Relative to the monthly climate data, the association between the tree-<span class="hlt">ring</span> data and the pentad climate data was more remarkable and accurate, and the reconstruction function based on the pentad climate was also more reliable and stable. We found that the major climatic factor limiting Huashan pine <span class="hlt">growth</span> was the precipitation of pentads 20–35 (from April 6 to June 24) rather than the well-known April–June precipitation. The pentad was also proved to be a better timescale for analysing the climate and tree <span class="hlt">growth</span> in the western and eastern Qinling Mountains. The formation of the earlywood density of Chinese pine (Pinus tabulaeformis) from Shimenshan in western Qinling was mainly affected by the maximum temperature of pentads 28–32 (from May 16 to June 9). The maximum temperature of pentads 28–33 (from May 16 to June 14) was the major factor affecting the <span class="hlt">ring</span> <span class="hlt">width</span> of Chinese pine from Shirenshan in eastern Qinling. PMID:27508933</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22384574','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22384574"><span id="translatedtitle">[Responses of Pinus sylvestris var. mongolica radial <span class="hlt">growth</span> to climate warming in Great Xing' an Mountins: a case study in Mangui].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Xing-Liang; He, Xing-Yuan; Chen, Zhen-Ju; Cui, Ming-Xing; Li, Na</p> <p>2011-12-01</p> <p>Based on the theory and methodology of dendrochronology, the tree <span class="hlt">ring</span> <span class="hlt">width</span> chronology of Pinus sylvestris var. mongolica in Mangui of Great Xing' an Mountains was developed, and the relationships between the standardized tree <span class="hlt">ring</span> <span class="hlt">width</span> chronology and local climate factors (temperature and precipitation) as well as the effects of climate factors on the P. sylvestris var. mongolica radial <span class="hlt">growth</span> were analyzed. In this region, the mean monthly temperature in April-August of current year was the main factor limiting the radial <span class="hlt">growth</span>, and the increasing mean monthly temperature from April to August had negative effects to the radial <span class="hlt">growth</span>. The simulation of the variations of the radial <span class="hlt">growth</span> by the mean monthly temperature change in April-August showed that the radial <span class="hlt">growth</span> of P. sylvestris var. mongolica would present a declining trend accompanied with the warmer and drier regional climate condition. PMID:22384574</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4729093','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4729093"><span id="translatedtitle">Autosomal <span class="hlt">ring</span> chromosomes in human genetic disorders</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2015-01-01</p> <p><span class="hlt">Ring</span> chromosomes arise following breakage and rejoining in both chromosome arms. They are heterogeneous with variable size and genetic content and can originate from any chromosome. Phenotypes associated with <span class="hlt">ring</span> chromosomes are highly variable as apart from any deletion caused by <span class="hlt">ring</span> formation, imbalances from <span class="hlt">ring</span> instability can also occur. Of interest is <span class="hlt">ring</span> chromosome 20 which has a significant association with epilepsy with seizure onset in early childhood. Severe <span class="hlt">growth</span> deficiency without major malformations is a common finding in the <span class="hlt">ring</span> chromosome carrier. This phenotype associated with <span class="hlt">ring</span> behaviour and mitotic instability and independent of the chromosome involved has been termed the “<span class="hlt">ring</span> syndrome”. Precise genotype-phenotype correlations for <span class="hlt">ring</span> chromosomes may not be possible as influencing factors vary depending on the extent of deletion in <span class="hlt">ring</span> formation, <span class="hlt">ring</span> instability and the level of mosaicism. Although <span class="hlt">ring</span> chromosomes usually arise as de novo events, familial transmission of <span class="hlt">rings</span> from carrier to offspring has been described and prenatal diagnosis for any pregnancies should always be considered. PMID:26835370</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007epsc.conf..873G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007epsc.conf..873G"><span id="translatedtitle">Physics of planetary <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gorkavyi, N.</p> <p>2007-08-01</p> <p>It is difficult to enumerate all the surprises presented by the planetary <span class="hlt">rings</span>. The Saturnian <span class="hlt">rings</span> are stratified into thousands of ringlets and the Uranian <span class="hlt">rings</span> are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the <span class="hlt">rings</span> is jagged and the <span class="hlt">rings</span> themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical <span class="hlt">rings</span>, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian <span class="hlt">ring</span> system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary <span class="hlt">rings</span> the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the <span class="hlt">growth</span> of short-wavelength waves and large-scale structures of the Saturnian <span class="hlt">rings</span> [1]. We have shown that the formation of the existing dense Uranian <span class="hlt">rings</span> is connected with the capture of positively drifting <span class="hlt">ring</span> particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense <span class="hlt">rings</span> at the positions of satellite resonances the collective interaction between resonant particles is amplified and the <span class="hlt">rings</span> can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C <span class="hlt">ring</span> an appreciable positive ballistic particle drift caused by the erosion of the B <span class="hlt">ring</span> by micrometeorites. It is therefore natural</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20709553','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20709553"><span id="translatedtitle"><span class="hlt">Ringing</span> wormholes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Konoplya, R.A.; Molina, C.</p> <p>2005-06-15</p> <p>We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (<span class="hlt">ringing</span>) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4239536','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4239536"><span id="translatedtitle">Red cell distribution <span class="hlt">width</span> and nonalcoholic steatohepatitis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gulcan Kurt, Yasemin; Cayci, Tuncer; Aydin, Fevzi Nuri; Agilli, Mehmet</p> <p>2014-01-01</p> <p>Red cell distribution <span class="hlt">width</span> is a measure of deviation of the volume of red blood cells. It is a marker of anisocytosis and often used to evaluate the possible causes of anemia. Elevated red cell distribution <span class="hlt">width</span> levels are also associated with acute and chronic inflammatory responses. In nonalcoholic steatohepatitis, inflammation is accompanied with steatosis. For assuming red cell distribution <span class="hlt">width</span> as a marker of nonalcoholic steatohepatitis, intervening factors such as levels of inflammatory markers should also be evaluated. PMID:25473202</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750049967&hterms=pyrotechnic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpyrotechnic','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750049967&hterms=pyrotechnic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpyrotechnic"><span id="translatedtitle">Optically thick line <span class="hlt">widths</span> in pyrotechnic flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Douda, B. E.; Exton, R. J.</p> <p>1975-01-01</p> <p>Experimentally determined sodium line <span class="hlt">widths</span> for pyrotechnic flares are compared with simple analytical, optically-thick-line-shape calculations. Three ambient pressure levels are considered (760, 150 and 30 torr) for three different flare compositions. The measured line <span class="hlt">widths</span> range from 1.3 to 481 A. The analytic procedure emphasizes the Lorentz line shape as observed under optically-thick conditions. Calculated <span class="hlt">widths</span> are in good agreement with the measured values over the entire range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012JGRE..117.0H16B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012JGRE..117.0H16B&link_type=ABSTRACT"><span id="translatedtitle">The transition from complex craters to multi-<span class="hlt">ring</span> basins on the Moon: Quantitative geometric properties from Lunar Reconnaissance Orbiter Lunar Orbiter Laser Altimeter (LOLA) data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, David M. H.; Head, James W.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.</p> <p>2012-03-01</p> <p>The morphologic transition from complex impact craters, to peak-<span class="hlt">ring</span> basins, and to multi-<span class="hlt">ring</span> basins has been well-documented for decades. Less clear has been the morphometric characteristics of these landforms due to their large size and the lack of global high-resolution topography data. We use data from the Lunar Orbiter Laser Altimeter (LOLA) instrument onboard the Lunar Reconnaissance Orbiter (LRO) spacecraft to derive the morphometric characteristics of impact basins on the Moon, assess the trends, and interpret the processes involved in the observed morphologic transitions. We first developed a new technique for measuring and calculating the geometric/morphometric properties of impact basins on the Moon. This new method meets a number of criteria that are important for consideration in any topographic analysis of crater landforms (e.g., multiple data points, complete range of azimuths, systematic, reproducible analysis techniques, avoiding effects of post-event processes, robustness with respect to the statistical techniques). The resulting data more completely capture the azimuthal variation in topography that is characteristic of large impact structures. These new calculations extend the well-defined geometric trends for simple and complex craters out to basin-sized structures. Several new geometric trends for peak-<span class="hlt">ring</span> basins are observed. Basin depth: A factor of two reduction in the depth to diameter (d/Dr) ratio in the transition from complex craters to peak-<span class="hlt">ring</span> basins may be characterized by a steeper trend than known previously. The d/Dr ratio for peak-<span class="hlt">ring</span> basins decreases with rim-crest diameter, which may be due to a non-proportional change in excavation cavity <span class="hlt">growth</span> or scaling, as may occur in the simple to complex transition, or increased magnitude of floor uplift associated with peak-<span class="hlt">ring</span> formation. Wall height, <span class="hlt">width</span>, and slope: Wall height and <span class="hlt">width</span> increase with increasing rim-crest diameter, while wall slope decreases; decreasing ratios</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EOSTr..94R.132S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EOSTr..94R.132S"><span id="translatedtitle">Tree <span class="hlt">ring</span> records capture long-term memory in climate systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schultz, Colin</p> <p>2013-03-01</p> <p>Measuring tree <span class="hlt">rings</span> is a mainstay technique for estimating ancient climatic conditions, with a tree's year-by-year <span class="hlt">growth</span> reflecting changes in precipitation and temperature. In some cases, paleoclimatological records compiled from tree <span class="hlt">ring</span> measurements can stretch for thousands of years. Based on recent research, climatologists have found that hydrological and other systems have long-term memory. Drawing on tree <span class="hlt">ring</span> measurements compiled from across the continental United States, Bowers et al. sought to determine whether such long-term relationships are preserved in <span class="hlt">ring</span> <span class="hlt">width</span> measurements. The authors analyzed the Hurst parameter—a measure of long-term memory—of 697 different tree <span class="hlt">ring</span> records that were collected from 10 tree species from locations across the United States. They found that though each tree species had a different mean value for its Hurst parameter, meaning that each species recorded long-term trends in the climate differently, they all fell within the range suggestive of their being able to properly represent long-term memory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820050022&hterms=radar+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradar%2Btheory','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820050022&hterms=radar+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradar%2Btheory"><span id="translatedtitle">Theory of radio occultation by Saturn's <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marouf, E. A.; Tyler, G. L.; Eshleman, V. R.</p> <p>1982-01-01</p> <p>The radio occultation technique, as applied to Saturn's <span class="hlt">rings</span>, is developed as a new method for the study of the physical properties of planetary <span class="hlt">ring</span> systems. The <span class="hlt">rings</span> are treated as a Doppler-spread radar target composed of an ensemble of discrete scatterers. The mathematical formulation of the received signal as a random-phasor-sum process is carried out following a conventional radar theory approach, providing a convenient starting point for deriving coherent signal parameters. A classical result is rederived for the equivalent refractive index of the medium. The analysis is generalized to include ringlets of arbitrary <span class="hlt">width</span> and it is shown that when the <span class="hlt">width</span> is such that two adjacent rays are differentially perturbed in phase, ray bending that causes focusing of the coherent signal may result. The diffuse component is also treated in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=286997','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=286997"><span id="translatedtitle">Effects of agaricus lilaceps fairy <span class="hlt">rings</span> on soil aggregation and microbial community structure in relation to <span class="hlt">growth</span> stimulation of western wheatgrass (pascopyrum smithii) in Eastern Montana rangeland</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Stimulation of plant productivity caused by Agaricus fairy <span class="hlt">rings</span> has been reported, but nothing is known about soil aggregation and the microbial community structure of the stimulated zone, particularly the communities that can bind to soil particles. We studied three concentric zones of Agaricus li...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4174874','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4174874"><span id="translatedtitle">Structural disorder and transformation in crystal <span class="hlt">growth</span>: direct observation of <span class="hlt">ring</span>-opening isomerization in a metal–organic solid solution</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jiang, Ji-Jun; He, Jian-Rong; Lü, Xing-Qiang; Wang, Da-Wei; Li, Guo-Bi; Su, Cheng-Yong</p> <p>2014-01-01</p> <p>A rare example is reported in which discrete Ag2 L 2 <span class="hlt">ring</span> and (AgL)∞ chain motifs [L = N,N′-bis(3-imidazol-1-yl-propyl)-pyromellitic diimide] co-crystallize in the same crystal lattice with varying ratios and degrees of disorder. Crystal structures obtained from representative crystals reveal compatible packing arrangements of the cyclic and polymeric isomers within the crystal lattice, which enables them to co-exist within a crystalline solid solution. A feasible pathway for transformation between the isomers is suggested via facile rotation of the coordinating imidazolyl groups. This chemical system could provide a chance for direct observation of <span class="hlt">ring</span>-opening isomerization at the crystal surface. Mass spectrometry and 1H NMR titration show a dynamic equilibrium between cyclic and oligomeric species in solution, and a potential crystallization process is suggested involving alignment of precursors directed by aromatic stacking interactions between pyromellitic diimide units, followed by <span class="hlt">ring</span>-opening isomerization at the interface between the solid and the solution. Both cyclic and oligomeric species can act as precursors, with interconversion between them being facile due to a low energy barrier for rotation of the imidazole <span class="hlt">rings</span>. Thermogravimetric analysis and variable-temperature powder X-ray diffraction indicate a transition to a different crystalline phase around 120°C, which is associated with loss of solvent from the crystal lattice. PMID:25295173</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21587453','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21587453"><span id="translatedtitle">NUCLEAR <span class="hlt">RINGS</span> IN GALAXIES-A KINEMATIC PERSPECTIVE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mazzuca, Lisa M.; Swaters, Robert A.; Veilleux, Sylvain; Knapen, Johan H.</p> <p>2011-10-01</p> <p>We combine DensePak integral field unit and TAURUS Fabry-Perot observations of 13 nuclear <span class="hlt">rings</span> to show an interconnection between the kinematic properties of the <span class="hlt">rings</span> and their resonant origin. The nuclear <span class="hlt">rings</span> have regular and symmetric kinematics, and lack strong non-circular motions. This symmetry, coupled with a direct relationship between the position angles and ellipticities of the <span class="hlt">rings</span> and those of their host galaxies, indicates that the <span class="hlt">rings</span> are in the same plane as the disk and are circular. From the rotation curves derived, we have estimated the compactness (v{sup 2}/r) up to the turnover radius, which is where the nuclear <span class="hlt">rings</span> reside. We find that there is evidence of a correlation between compactness and <span class="hlt">ring</span> <span class="hlt">width</span> and size. Radially wide <span class="hlt">rings</span> are less compact, and thus have lower mass concentration. The compactness increases as the <span class="hlt">ring</span> <span class="hlt">width</span> decreases. We also find that the nuclear <span class="hlt">ring</span> size is dependent on the bar strength, with weaker bars allowing <span class="hlt">rings</span> of any size to form.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21289923','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21289923"><span id="translatedtitle">Critical comparison of Kramers' fission <span class="hlt">width</span> with the stationary <span class="hlt">width</span> from the Langevin equation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sadhukhan, Jhilam; Pal, Santanu</p> <p>2009-06-15</p> <p>It is shown that Kramers' fission <span class="hlt">width</span>, originally derived for a system with constant inertia, can be extended to systems with a deformation-dependent collective inertia, which is the case for nuclear fission. The predictions of Kramers' <span class="hlt">width</span> for systems with variable inertia are found to be in very good agreement with the stationary fission <span class="hlt">widths</span> obtained by solving the corresponding Langevin equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27154752','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27154752"><span id="translatedtitle">Microwave-assisted stereoselective approach to novel steroidal <span class="hlt">ring</span> D-fused 2-pyrazolines and an evaluation of their cell-<span class="hlt">growth</span> inhibitory effects in vitro.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mótyán, Gergő; Kovács, Ferenc; Wölfling, János; Gyovai, András; Zupkó, István; Frank, Éva</p> <p>2016-08-01</p> <p>Novel <span class="hlt">ring</span> D-condensed 2-pyrazolines in the Δ(5)-androstene series were efficiently synthesized from 16-dehydropregnenolone or its acetate with different arylhydrazines or methylhydrazine, respectively, under microwave irradiation. The reactions are assumed to occur via hydrazone intermediates, followed by intramolecular 1,4-addition leading to the fused heteroring stereoselectively with a 16α,17α-cis <span class="hlt">ring</span> junction. The synthesized compounds were subjected to in vitro pharmacological studies of their antiproliferative activities against four human breast (MCF7, T47D, MDA-MB-231 and MDA-MB-361) and three cervical (HeLa, C33A and SiHA) malignant cell lines. Flow cytometry revealed that the most potent agent elicited a cell cycle disturbance. PMID:27154752</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013EGUGA..15.2347S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013EGUGA..15.2347S&link_type=ABSTRACT"><span id="translatedtitle">A measuring tool for tree-<span class="hlt">rings</span> analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shumilov, Oleg; Kanatjev, Alexander; Kasatkina, Elena</p> <p>2013-04-01</p> <p>A special tool has been created for the annual tree-<span class="hlt">ring</span> <span class="hlt">widths</span> measurement and analysis. It consists of professional scanner, computer system and software. This created complex in many aspects does not yield the similar systems (LINTAB, WinDENDRO), but in comparison to manual measurement systems, it offers a number of advantages: productivity gain, possibility of archiving the results of the measurements at any stage of the processing, operator comfort. It has been developed a new software, allowing processing of samples of different types (cores, saw cuts), including those which is difficult to process, having got a complex wood structure (inhomogeneity of growing in different directions, missed, light and false <span class="hlt">rings</span> etc.). This software can analyze pictures made with optical scanners, analog or digital cameras. The complex software program was created on programming language C++, being compatible with modern operating systems like Windows X. Annual <span class="hlt">ring</span> <span class="hlt">widths</span> are measured along paths traced interactively. These paths can have any orientation and can be created so that <span class="hlt">ring</span> <span class="hlt">widths</span> are measured perpendicular to <span class="hlt">ring</span> boundaries. A graphic of <span class="hlt">ring-widths</span> in function of the year is displayed on a screen during the analysis and it can be used for visual and numerical cross-dating and comparison with other series or master-chronologies. <span class="hlt">Ring</span> <span class="hlt">widths</span> are saved to the text files in a special format, and those files are converted to the format accepted for data conservation in the International Tree-<span class="hlt">Ring</span> Data Bank. The created complex is universal in application that will allow its use for decision of the different problems in biology and ecology. With help of this complex it has been reconstructed a long-term juniper (1328-2004) and pine (1445-2005) tree-<span class="hlt">ring</span> chronologies on the base of samples collected at Kola Peninsula (northwestern Russia).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18533520','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18533520"><span id="translatedtitle">[Variations of Picea crassifolia tree-<span class="hlt">ring</span> cell structure and their implications to past climate in eastern margin of Qaidam Basin, Northwest China].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Yan; Liang, Er-Yuan; Shao, Xue-mei</p> <p>2008-03-01</p> <p>Tree-<span class="hlt">ring</span> samples of Picea crassifolia were collected from the upper tree-line in the eastern mountainous area of Qaidam Basin in Qinghai Province. The tree-<span class="hlt">ring</span> <span class="hlt">width</span> and the cell number and size of the tree-<span class="hlt">ring</span> were measured, and the standard chronologies for the early-wood cell number, late-wood cell number, total cell number of tree-<span class="hlt">rings</span>, maximum cell size, and minimum cell size were constructed. By using correlation analysis and the response functions between cell characteristic indices and 1970-2000 climate factors at Chaka meteorological station which was close to the sampling site, the relationships between P. crassifolia <span class="hlt">growth</span> at cell scale and climate factors were discussed. The results showed that the early-wood cell number was positively correlated to the wintertime temperature from previous October to current March, while the late-wood cell number was positively correlated to the minimum temperature in previous November and December and to the mean temperature in current July and August. Both the early-wood and the late-wood cell numbers were negatively correlated to the precipitation in July, and the early-wood cell number was positively correlated to the precipitation in May. The chronology of maximum cell size of early-wood was positively related to the precipitation in February, while that of minimum cell size of late-wood was positivelyrelated to the precipitation in August. It was concluded that the cell number and cell size could not only reveal the information of temperature change, which was recorded by tree <span class="hlt">ring</span> <span class="hlt">width</span> as well, but also provide additional information of precipitation. Since different types of tree-<span class="hlt">ring</span> indices contained different climate information, multiple aspects of climate change information could be extracted from different tree-<span class="hlt">ring</span> indices of the same species at the same site, and the cell level tree <span class="hlt">ring</span> characteristics had great potential to supply the information regarding past climate. PMID:18533520</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...93...67L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...93...67L"><span id="translatedtitle">Tree-<span class="hlt">ring</span> stable carbon isotope-based May-July temperature reconstruction over Nanwutai, China, for the past century and its record of 20th century warming</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Yu; Wang, Yanchao; Li, Qiang; Song, Huiming; Linderholm, Hans W.; Leavitt, Steven W.; Wang, Ruiyuan; An, Zhisheng</p> <p>2014-06-01</p> <p><span class="hlt">Growth</span> anomaly of trees in some regions was detected under current episode of rapid warming. This raises a dilemma for temperature reconstructions by using tree-<span class="hlt">ring</span> <span class="hlt">width</span> which is believed to be the most important proxy on inter-annual temperature reconstruction during the past millenniums. Here we employed the tree-<span class="hlt">ring</span> δ13C to reconstruct temperature variations for exploring their potential on capturing signals of rapid warming, and to test how its difference with the tree-<span class="hlt">ring</span> <span class="hlt">width</span> based reconstruction. In this study the mean May-July temperature (TM-J) was reconstructed over the past century by tree-<span class="hlt">ring</span> δ13C of Chinese pine trees growing in the Nanwutai region. The explained variance of the reconstruction was 43.3% (42.1% after adjusting the degrees of freedom). Compared to a <span class="hlt">ring-width</span> temperature reconstruction (May-July) from the same site, the tree-<span class="hlt">ring</span> δ13C-based temperature reconstruction offered two distinct advantages: 1) it captured a wider range of temperature variability, i.e., at least May-July, even over a longer part of the year, January-September; and 2) the reconstruction preserved more low-frequency climate information than that of <span class="hlt">ring</span> <span class="hlt">width</span> did. The 20th century warming was well represented in the Nanwutai tree-<span class="hlt">ring</span> δ13C temperature reconstruction, which implied that stable carbon isotope of tree <span class="hlt">rings</span> potentially represents temperature variations during historical episodes of rapid warming. A spatial correlation analysis showed that our temperature reconstruction represented climate variations over the entire Loess Plateau in north-central China. Significant positive correlations (p < 0.1) were found between the temperature reconstruction and ENSO, as well as SSTs in the Pacific and Indian Oceans. The reconstruction showed the periodicities of 22.78-, 4.16-, 3.45-3.97- and 2.04-2.83-year quasi-cycles at a 95% confidence level. Our results suggested that temperature variability in the Nanwutai region may be linked to Pacific and Indian</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930057613&hterms=dark+matter+galaxy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ddark%2Bmatter%2Bgalaxy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930057613&hterms=dark+matter+galaxy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ddark%2Bmatter%2Bgalaxy"><span id="translatedtitle">Hydrodynamic models of the Cartwheel <span class="hlt">ring</span> galaxy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Struck-Marcell, Curtis; Higdon, James L.</p> <p>1993-01-01</p> <p>A series of increasingly sophisticated models of the Cartwheel <span class="hlt">ring</span> galaxy is studied in order to test the collisional model for the galaxy formation and examine the star formation processes in this unique environment, using new data acquired in the last decade. The simulations provided some possible answers to a number of questions about the Cartwheel. First, an explanation for the wide spacing between inner and outer <span class="hlt">rings</span> is suggested by the simple epicyclic kinematics within the dark matter-dominated potential implied by H I rotation curve. These models and the kinematic model of Struck-Marcell and Lotan (1990) also predict that the outer <span class="hlt">ring</span> should be relatively weak, while the second inner <span class="hlt">ring</span> should be stronger, with a dense orbit-crossing region of significant <span class="hlt">width</span> bounded by sharp, caustic edges. The collisional model is given support by the agreement between the observations and the morphological and kinematic properties of the numerical simulations presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26327638','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26327638"><span id="translatedtitle">Pollution control enhanced spruce <span class="hlt">growth</span> in the "Black Triangle" near the Czech-Polish border.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kolář, Tomáš; Čermák, Petr; Oulehle, Filip; Trnka, Miroslav; Štěpánek, Petr; Cudlín, Pavel; Hruška, Jakub; Büntgen, Ulf; Rybníček, Michal</p> <p>2015-12-15</p> <p>Norway spruce (Picea abies (L.) Karst.) stands in certain areas of Central Europe have experienced substantial dieback since the 1970s. Understanding the reasons for this decline and reexamining the response of forests to acid deposition reduction remains challenging because of a lack of long and well-replicated tree-<span class="hlt">ring</span> <span class="hlt">width</span> chronologies. Here, spruce from a subalpine area heavily affected by acid deposition (from both sulfur and nitrogen compounds) is evaluated. Tree-<span class="hlt">ring</span> <span class="hlt">width</span> measurements from 98 trees between 1000 and 1350m above sea level (a.s.l.) reflected significant May-July temperature signals. Since the 1970s, acid deposition has reduced the <span class="hlt">growth</span>-climate relationship. Efficient pollution control together with a warmer but not drier climate most likely caused the increased <span class="hlt">growth</span> of spruce stands in this region, the so-called "Black Triangle," in the 1990s. PMID:26327638</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009LNCS.5874..385K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009LNCS.5874..385K"><span id="translatedtitle">Bipartite Graphs of Large Clique-<span class="hlt">Width</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korpelainen, Nicholas; Lozin, Vadim V.</p> <p></p> <p>Recently, several constructions of bipartite graphs of large clique-<span class="hlt">width</span> have been discovered in the literature. In the present paper, we propose a general framework for developing such constructions and use it to obtain new results on this topic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1014874','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1014874"><span id="translatedtitle">Asymmetric dipolar <span class="hlt">ring</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.</p> <p>2010-11-16</p> <p>A device having a dipolar <span class="hlt">ring</span> surrounding an interior region that is disposed asymmetrically on the <span class="hlt">ring</span>. The dipolar <span class="hlt">ring</span> generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar <span class="hlt">ring</span> in the plane of the <span class="hlt">ring</span>. The <span class="hlt">ring</span> may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24483064','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24483064"><span id="translatedtitle">[Effects of elevated ozone on Pinus armandii <span class="hlt">growth</span>: a simulation study with open-top chamber].</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Chang-Fu; Liu, Chen; He, Xing-Yuan; Ruan, Ya-Nan; Xu, Sheng; Chen, Zhen-Ju; Peng, Jun-Jie; Li, Teng</p> <p>2013-10-01</p> <p>By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the <span class="hlt">growth</span> of Pinus armandii under elevated ozone, and explored the evolution dynamics and adaptation mechanisms of typical forest ecosystems to ozone enrichment. Elevated ozone inhibited the stem <span class="hlt">growth</span> of P. armandii significantly, with the annual <span class="hlt">growth</span> of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual <span class="hlt">growth</span> of tree-<span class="hlt">ring</span> <span class="hlt">width</span> and the annual <span class="hlt">ring</span> cells number decreased by 11.5% and 54.1%, respectively, but no significant change was observed in the diameter of tracheid. At regional scale, the fluctuation of ozone concentration showed significant correlation with the variation of local vegetation <span class="hlt">growth</span> (NDVI). PMID:24483064</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010EGUGA..12.4488S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010EGUGA..12.4488S&link_type=ABSTRACT"><span id="translatedtitle">The climate-isotope relationship of tree-<span class="hlt">rings</span> at temperate, high-altitude and high-latitude sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saurer, Matthias; Kress, Anne; Sidorova, Olga; Siegwolf, Rolf</p> <p>2010-05-01</p> <p>Tree-<span class="hlt">ring-width</span> and latewood density provide climate information particularly at extreme sites where <span class="hlt">growth</span> is limited by a single factor. It is not clear, however, if this general principle also holds for stable carbon isotope (δ13C) or oxygen isotope (δ18O) variations. With increasing number of isotope studies and developing isotopic networks (ISONET, MILLENNIUM), the influence of site conditions on the climate-isotope relationship can now be systemically investigated. Our studies with trees growing in Europe and Siberia indicate the following: (1) Significant climate-isotope relationship are found for temperate regions where neither temperature nor precipitation are strongly limiting <span class="hlt">growth</span> (Saurer et al. 2008) (2) The climate signal does not depend as much on site conditions as it does for tree-<span class="hlt">ring</span> <span class="hlt">width</span> and latewood density (3) A particularly strong carbon isotope climate signal reflecting drought is found for an Alpine larch chronology (Kress et al. 2009) (4) Isotopes at high-latitude Siberian sites contain a mixed temperature-precipitation signal (Sidorova et al. 2009). Overall, we can state that stable isotopes in tree-<span class="hlt">rings</span> provide complimentary information to tree-<span class="hlt">ring</span> <span class="hlt">width</span> and density and extend the geographical range as well as the derived climate parameters significantly. Kress, A., Saurer, M., Siegwolf, R.T.W., Frank, D.C., Esper, J. and Bugmann, H.: A 350-year drought reconstruction from Alpine tree-<span class="hlt">ring</span> stable isotopes. Global Biogeochemical Cycles, in press Saurer, M., Cherubini, P., Reynolds-Henne, C. E., Treydte, K. S., Anderson, W. T., and Siegwolf, R. T. W.: An investigation of the common signal in tree <span class="hlt">ring</span> stable isotope chronologies at temperate sites, Journal of Geophysical Research-Biogeosciences, 113, 10.1029/2008jg000689, 2008. Sidorova, O. V., Siegwolf, R. T. W., Saurer, M., Naurzbaev, M. M., Shashkin, A. V., and Vaganov, E. A.: Spatial patterns of climatic changes in the Eurasian north reflected in Siberian larch tree-<span class="hlt">ring</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PhRvB..69n4421C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PhRvB..69n4421C"><span id="translatedtitle">Magnetic configurations in 160 520-nm-diameter ferromagnetic <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castaño, F. J.; Ross, C. A.; Eilez, A.; Jung, W.; Frandsen, C.</p> <p>2004-04-01</p> <p>The remanent states and hysteretic behavior of thin-film magnetic <span class="hlt">rings</span> has been investigated experimentally and by micromagnetic modeling. <span class="hlt">Rings</span> of diameters 160 520 nm, made from Co using lift-off processing, show three distinct remanent states: a vortex state, an “onion” state with two head-on walls, and a “twisted” state containing a 360° wall. The range of stability of these states varies with <span class="hlt">ring</span> geometry, with smaller <span class="hlt">width</span> <span class="hlt">rings</span> showing higher switching fields and greater variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010048660&hterms=saturn+rings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsaturn%2Brings','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010048660&hterms=saturn+rings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsaturn%2Brings"><span id="translatedtitle">Saturn's Spectacular <span class="hlt">Ring</span> System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)</p> <p>2001-01-01</p> <p>Saturn's beautiful <span class="hlt">rings</span> have fascinated astronomers since they were first observed by Galileo in 1610. The main <span class="hlt">rings</span> consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The <span class="hlt">ring</span> disk is exceptionally thin - the typical local thickness of the bright <span class="hlt">rings</span> is tens of meters, whereas the diameter of the main <span class="hlt">rings</span> is 250,000 km! The main <span class="hlt">rings</span> exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main <span class="hlt">rings</span> lie tenuous dust <span class="hlt">rings</span>, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of <span class="hlt">ring</span>-moon interactions, recent advances in our understanding of various aspects of the <span class="hlt">rings</span> obtained from observations taken during 1995 when the <span class="hlt">rings</span> appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17..686S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17..686S&link_type=ABSTRACT"><span id="translatedtitle">Salix polaris <span class="hlt">growth</span> responses to active layer detachment and solifluction processes in High Arctic.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siekacz, Liliana</p> <p>2015-04-01</p> <p>The work is dedicated to demonstrate the potential of Salix polaris grow properties in the dendrogemorphologic image, analyzing periglacially induced slope processes in the high Arctic.. Observed anatomical and morphological plants responses to solifluction and active layer detachment processes are presented qualitatively and quantitatively as a summary of presented features frequency. The results are discussed against the background of the other research results in this field. The investigations was performed in Ebba valley, in the vicinity of Petunia Bay, northernmost part of Billefjorden in central Spitsbergen (Svalbard). Environmental conditions are characterized by annual precipitation sum lower than 200 mm (Hagen et al.,1993) and average summer temperature of about 5°C, with maximum daily temperatures rarely exceeding 10°C (Rachlewicz, 2009). Collected shrub material was prepared according to the methods presented by Schweingruber and Poschlod (2005). Thin (approx. 15-20μm) sections of the whole cross-section were prepared with a sledge microtome, stained with Safranine and Astra blue and finally permanently fixed on microslides with Canada balsam and dried. Snapshots were taken partially for each cross-section with digital camera (ColorView III, Olympus) connected to a microscope (Olympus BX41) and merged into one, high resolution image. After all, <span class="hlt">ring</span> <span class="hlt">widths</span> were measured in 3-4 radii in every single cross-section using ImageJ software. Analyzed plants revealed extremely harsh environmental conditions of their <span class="hlt">growth</span>. Buchwał et al. (2013) provided quantitative data concerning missing <span class="hlt">rings</span> and partially missing <span class="hlt">rings</span> in shrubs growing on Ebba valley floor. Mean <span class="hlt">ring</span> <span class="hlt">width</span> at the level of 79μm represents one of the smallest values of yearly <span class="hlt">growth</span> ever noted. The share of missing <span class="hlt">rings</span> and partially missing <span class="hlt">rings</span> was 11,2% and 13,6% respectively. Plants growing on Ebba valley slope indicate almost twice smaller values of <span class="hlt">ring</span> <span class="hlt">width</span> (41μm), and higher</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4047095','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4047095"><span id="translatedtitle">C3HC4-Type <span class="hlt">RING</span> Finger Protein NbZFP1 Is Involved in <span class="hlt">Growth</span> and Fruit Development in Nicotiana benthamiana</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wu, Wenxian; Cheng, Zhiwei; Liu, Mengjie; Yang, Xiufen; Qiu, Dewen</p> <p>2014-01-01</p> <p>C3HC4-type <span class="hlt">RING</span> finger proteins constitute a large family in the plant kingdom and play important roles in various physiological processes of plant life. In this study, a C3HC4-type zinc finger gene was isolated from Nicotiana benthamiana. Sequence analysis indicated that the gene encodes a 24-kDa protein with 191 amino acids containing one typical C3HC4-type zinc finger domain; this gene was named NbZFP1. Transient expression of pGDG-NbZFP1 demonstrated that NbZFP1 was localized to the chloroplast, especially in the chloroplasts of cells surrounding leaf stomata. Virus-induced gene silencing (VIGS) analysis indicated that silencing of NbZFP1 hampered fruit development, although the height of the plants was normal. An overexpression construct was then designed and transferred into Nicotiana benthamiana, and PCR and Southern blot showed that the NbZFP1 gene was successfully integrated into the Nicotiana benthamiana genome. The transgenic lines showed typical compactness, with a short internode length and sturdy stems. This is the first report describing the function of a C3HC4-type <span class="hlt">RING</span> finger protein in tobacco. PMID:24901716</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..MARW37008R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..MARW37008R"><span id="translatedtitle">Polarization Transitions in Quantum <span class="hlt">Ring</span> Arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roostaei, Bahman; Mullen, Kieran</p> <p>2004-03-01</p> <p>We calculate the zero temperature electrostatic properties of charged one and two dimensional arrays of <span class="hlt">rings</span>, in the classical and quantum limits. Each <span class="hlt">ring</span> is assumed to be an ideal <span class="hlt">ring</span> of negligible <span class="hlt">width</span>, with exactly one electron on the <span class="hlt">ring</span> that interacts only with nearest neighbor <span class="hlt">rings</span>. In the classical limit we find that if the electron is treated as a point particle, the 1D array of <span class="hlt">rings</span> can be mapped to an Ising antiferromagnet, while the 2D array groundstate is a four-fold degenerate ``stripe" phase. In contrast, if we treat the electrical charge as a continuous fluid, the distribution will not spontaneously break symmetry, but will develop a charge distribution reflecting the symmetry of the array. In the quantum limit, the competition between the kinetic energy and Coulomb energy allows for a transition between unpolarized and polarized states as a function of the <span class="hlt">ring</span> parameters. This allows for a new class of polarizable materials whose transitions are based on geometry, rather than a structural transition in a unit cell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGC21C0888P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGC21C0888P"><span id="translatedtitle">Isotope variability in larch tree <span class="hlt">rings</span> of Siberia: climate and ecology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panyushkina, I. P.; Knorre, A.; Leavitt, S. W.; Kirdyanov, A.; Grachev, A.; Brukhanova, M.; Vaganov, E. A.</p> <p>2010-12-01</p> <p>Paleoclimate reconstructions from tree-<span class="hlt">ring</span> <span class="hlt">widths</span> and maximum wood density are most successful in localities with extreme climates for particular tree species that are most responsive. Climate proxy records from other, less conventional, tree-<span class="hlt">ring</span> parameters have been rapidly increasing over the last decade. We assembled a unique dataset of carbon and oxygen isotope ratios of larch tree <span class="hlt">rings</span> from the northern and southern tree-lines of Siberia, variously sub-sampled and analyzed (whole wood and cellulose & annual and 5-year sequences from individual trees and pooled). Larch samples from the north in Taymyr (Larix gmelinii Rupr.) published by Sidorova et al. (2010) and from the south collected in Khakasia (Larix sibirica Ledeb.) both came from highly temperate continental climates exhibiting similar amounts of precipitation and observed temperature trends. However, the sites differ because temperature is the dominant factor limiting radial tree <span class="hlt">growth</span> in the north, whereas precipitation is the dominant limiting factor in the south. Climatic signals documented in the chronologies of tree-<span class="hlt">ring</span> <span class="hlt">widths</span>, wood density, and stable carbon and oxygen isotopes were compared from 1896 to 2005 and interpreted based on site ecology and larch physiology. We found a wide range of climatic responses in the variability of isotopic ratios, which suggest influence by combined interaction of precipitation and temperature changes rather than either climate factor alone. We discuss the improvement in our understanding of climatic mechanisms that control isotope compositions and tree <span class="hlt">growth</span> in boreal forests. At certain locations where tree-<span class="hlt">ring</span> <span class="hlt">widths</span> are less sensitive to climate factors, isotope analysis may have greater value to successful climate modeling. It seems crucial to measure both isotopes (C and O) in tree <span class="hlt">rings</span> and to incorporate these mechanisms properly in developing reliable climate predictors. It is noteworthy that despite the identified differences in climatic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JESS..120..713R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JESS..120..713R"><span id="translatedtitle">Tree-<span class="hlt">ring</span> variation in teak ( Tectona grandis L.) from Allapalli, Maharashtra in relation to moisture and Palmer Drought Severity Index, India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ram, Somaru; Borgaonkar, H. P.; Munot, A. A.; Sikder, A. B.</p> <p>2011-08-01</p> <p>We developed a <span class="hlt">ring-width</span> chronology of teak ( Tectona grandis L.) from a moisture stressed area in Maharashtra, India. Bootstrapped correlation analysis indicated that moisture index (MI) and Palmer Drought Severity Index (PDSI) showed better performance rather than same year rainfall over the region. Tree-<span class="hlt">ring</span> variations were most correlated positively with PDSI during different seasons compared with MI. Significant strong positive correlation with MI, and negative association with temperature and potential evapotranspiration (PET) were found during previous and current year post-monsoon (ON). This study shows that the moisture availability during the post-monsoon of the previous year has a significant role in the development of annual <span class="hlt">growth</span> <span class="hlt">rings</span>. The reconstructed previous year post-monsoon (-ON) moisture index for the period 1866-1996 indicates 3.5 and 29.3 years periodicities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4861Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4861Y"><span id="translatedtitle">The ralationship between the Tamarix spp. <span class="hlt">growth</span> and lake level change in the Bosten Lake,northwest China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, Mao; Hou, JiaWen</p> <p>2015-04-01</p> <p>Dendrochronology methods are used to analyze the characteristics of Tamarix spp. <span class="hlt">growth</span> in Bosten Lake. Based on the long-term annual and monthly data of lake level, this paper models the relationship between <span class="hlt">ring</span> <span class="hlt">width</span> of Tamarix spp. and lake level change. The sensitivity index is applied to determine the rational change range of lake level for protecting the Tamarix spp. <span class="hlt">growth</span>. The results show that :( 1) the annual change of lake level in Bosten Lake has tree evident stages from 1955 to 2012. The monthly change of lake level has two peak values and the seasonal change is not significant; (2) the average value of radical <span class="hlt">width</span> of Tamarix spp. is 3.39mm. With the increment of Tamarix spp. annual <span class="hlt">growth</span> , the average radical <span class="hlt">width</span> has a decreasing trend, which is similar to the annual change trend of lake level in the same years ;( 3) the response of the radical <span class="hlt">width</span> of Tamarix spp. to annual change of lake level is sensitive significantly. When the lake level is 1045.66m, the Sk value of radical <span class="hlt">width</span> of Tamarix spp. appears minimum .when the lake level is up to1046.27m, the Sk value is maximum. Thus the sensitivity level of radical <span class="hlt">width</span> of Tamarix spp. is 1045.66- 1046.27m which could be regarded as the rational lake level change range for protecting the Tamarix spp. <span class="hlt">growth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..304K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..304K"><span id="translatedtitle">Tree <span class="hlt">rings</span>, solar radiation and ice cover of the Barents sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kasatkina, Elena; Shumilov, Oleg; Timonen, Mauri; Kanatjev, Alexandr</p> <p>2015-04-01</p> <p>Intercomparisons of the Kola Peninsula tree-<span class="hlt">ring</span> records, ice cover of the Barents sea and sea and surface temperatures have been made. Tree-<span class="hlt">ring</span> series over the last 100 years showed a highly significant correlation with the sea surface temperatures and ice cover (r=-0.57, p<0.05). It should be noted that the correlation between the tree-<span class="hlt">ring</span> <span class="hlt">widths</span> and local temperatures was not so high. We suppose that a possible reason seems to be the prevailing influence of solar irradiance and their UV components on tree <span class="hlt">growth</span> in the Kola North. It is known that solar variability and fluctuations of solar irradiance in the UV band of the spectrum has increased over the last decades. In addition, there are frequent cases of total ozone content depletions (or so-called ozone mini-holes) resulting in increased UV-B. The recent studies demonstrate that many boreal and subarctic plants have increased susceptibility to UV-B radiation. An indirect confirmation of the hypothesis proposed is a close relationship between solar total irradiance and global sea surface temperature (Reid, 2000). The results of spectral MTM-analysis also revealed periodicities close to the solar cycles in the ice cover and tree-<span class="hlt">ring</span> records. These results confirm the above-mentioned interpretation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864815','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864815"><span id="translatedtitle">Stirling engine piston <span class="hlt">ring</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Howarth, Roy B.</p> <p>1983-01-01</p> <p>A piston <span class="hlt">ring</span> design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the <span class="hlt">ring</span>'s surface and thereby allowing the contact pressure on the <span class="hlt">ring</span> to be predetermined through the use of a preloaded expander <span class="hlt">ring</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4880555','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4880555"><span id="translatedtitle">Biological Basis of Tree-<span class="hlt">Ring</span> Formation: A Crash Course</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rathgeber, Cyrille B. K.; Cuny, Henri E.; Fonti, Patrick</p> <p>2016-01-01</p> <p>Wood is of crucial importance for man and biosphere. In this mini review, we present the fundamental processes involved in tree-<span class="hlt">ring</span> formation and intra-annual dynamics of cambial activity, along with the influences of the environmental factors. During wood formation, new xylem cells produced by the cambium are undergoing profound transformations, passing through successive differentiation stages, which enable them to perform their functions in trees. Xylem cell formation can be divided in five major phases: (1) the division of a cambial mother cell that creates a new cell; (2) the enlargement of this newly formed cell; (3) the deposition of its secondary wall; (4) the lignification of its cell wall; and finally, (5) its programmed cell death. In most regions of the world cambial activity follows a seasonal cycle. At the beginning of the growing season, when temperature increases, the cambium resumes activity, producing new xylem cells. These cells are disposed along radial files, and start their differentiation program according to their birth date, creating typical developmental strips in the forming xylem. The <span class="hlt">width</span> of these strips smoothly changes along the growing season. Finally, when climatic conditions deteriorate (temperature or water availability in particular), cambial activity stops, soon followed by cell enlargement, and later on by secondary wall deposition. Without a clear understanding of the xylem formation process, it is not possible to comprehend how annual <span class="hlt">growth</span> <span class="hlt">rings</span> and typical wood structures are formed, recording normal seasonal variations of the environment as well as extreme climatic events. PMID:27303426</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27326928','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27326928"><span id="translatedtitle">Actin <span class="hlt">Rings</span> of Power.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp</p> <p>2016-06-20</p> <p>Circular or <span class="hlt">ring</span>-like actin structures play important roles in various developmental and physiological processes. Commonly, these <span class="hlt">rings</span> are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger <span class="hlt">ring</span> constriction. Actomyosin <span class="hlt">ring</span> constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin <span class="hlt">ring</span>-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin <span class="hlt">ring</span>-like structures in various morphogenetic processes, shedding light on how those different <span class="hlt">rings</span> have been adapted to fulfill their specific roles. PMID:27326928</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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